We intend to use the net proceeds from the exercise of Subscription RightsOffering for general corporate purposes, which may include research and development expenses, capital expenditures, working capital and general and administrative expenses, and potential acquisitions of or investments in businesses, products and technologies that complement our business, although we have no present commitments or agreements to make any such acquisitions or investments as of the date of this prospectus. We expect to use any proceeds we receive from the exercise of Class E Warrants for substantially the same purposes and in substantially the same manner. Pending these uses, we intend to invest the funds in short-term, investment grade, interest-bearing securities. It is possible that, pending their use, we may invest the net proceeds in a way that does not yield a favorable, or any, return for us.

Our management will have broad discretion as to the allocation of the net proceeds from this offering and could use them for purposes other than those contemplated at the time of commencement of this offering.

DILUTIONCAPITALIZATION

Purchasers of Units in the Rights Offering will experience an immediate dilution of the net tangible book value per share ofThe following table sets forth our common stock. Our net tangible book valueactual cash and cash equivalents and capitalization, each as of SeptemberJune 30, 2019 was approximately $5,985,000, or $2.5322023, and as adjusted to give effect to the issuance and sale of securities in this offering at an assumed public offering price of $0.5615 per share ofUnit, which is the last reported sale price for our common stock (based upon 2,363,991 shareson the Nasdaq Capital Market on October 19, 2023, and an aggregate offering amount of $4.35 million, after deducting the placement agent fees and estimated offering expenses payable by us.

The as adjusted information set forth below is illustrative only and will be adjusted based on the actual public offering price and other terms of this offering determined at pricing.

You should read this information in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our common stock outstanding). Net tangible book value per share is equal tocondensed consolidated financial statements and related notes appearing in our total tangible assets lessQuarterly Report on Form 10-Q for the quarters ended June 30, 2023 and March 31, 2023, and our total liabilities, dividedAnnual Report on Form 10-K for the fiscal year ended December 31, 2022, which are incorporated by reference in this prospectus.

Except as otherwise noted, all information in this prospectus reflects and assumes (i) no sale of pre-funded warrants in this offering, which, if sold, would reduce the number of shares of our outstanding common stock.

Dilution per share of common stock equals the difference between the amount paid by purchasers of Units in the Rights Offering (ascribing no value to the Warrants contained in the Units)that we are offering on a one-for-one basis and the net tangible book value per share of our common stock immediately after the Rights Offering.

Based on the sale by us in this Rights Offering of a maximum of Units at the Subscription Price of $1,000 per Unit (assuming(ii) no exercise of the Warrants),Class E Warrants issued in this offering. The above discussion and after deducting estimated offering expenses and dealer-manager fees and expenses payable by us, our pro forma net tangible book valuetable are based on 4,208,027 shares of common stock outstanding as of SeptemberJune 30, 2019 would have been approximately $          million, or $          per share. This represents an immediate increase in pro forma net tangible book value to existing stockholders of $          per share2023 and an immediate dilution to purchasers in the Rights Offering of $         per share. The following table illustrates this per-share dilution:

The information above isexcludes, as of September 30, 2019 and excludes:such date:

MARKET PRICE AND DIVIDEND POLICY

Our shares of Common Stockcommon stock are currently quoted on The Nasdaq Capital Market under the symbol “SINT”. On December 6, 2019,October 19, 2023, the last reported sales price of our Common Stockcommon stock on Nasdaq was $1.52.$0.5615.

Holders of Record

As of December 6, 2019,October 19, 2023, we had approximately 360159 holders of record of our Common Stock.common stock. Because many of our shares of Common Stockcommon stock are held by brokers and other institutions on behalf of stockholders, this number is not indicative of the total number of stockholders represented by these stockholders of record.

Dividends

We have not declared or paid dividends to stockholders since inception and do not plan to pay cash dividends in the foreseeable future. We currently intend to retain earnings, if any, to finance our growth.

Issuer Purchases of Equity Securities

None

THE RIGHTS OFFERING

The Subscription Rights

We are distributing to the record holders of our common stock, Series B Preferred Stock, and Participating Warrants, at no charge, non-transferable Subscription Rights to purchase one Unit at a subscription price of $1,000 per Unit. Each Basic Subscription Right will entitle you to purchase one share of our preferred stock and              Warrants. Each Warrant will be exercisable for one share of our common stock at an exercise price of $           per share from the date of issuance through the expiration five years from the date of issuance. Each record holder of our common stock, Series B Preferred Stock, and holders of Participating Warrants, will receive one Subscription Right for every share of our common stock (including each share of common stock issuable upon conversion of Series B Preferred Stock and exercise of Participating Warrants) owned by such record holder as of the Record Date. Each Subscription Right entitles the record holder to a Basic Subscription Right and an Over-Subscription Privilege.

Basic Subscription Rights

Your Basic Subscription Rights will entitle you to purchase Units, each comprised of one share of our Preferred Stock and             Warrants. For example, if you owned 100 shares of common stock as of the Record Date, you will receive 100 Subscription Rights and will have the right to purchase 100 shares of our Preferred Stock and Warrants to purchase            shares of our common stock for $1,000 per Unit, or a total payment of $100,000. You may exercise all or a portion of your Basic Subscription Rights, or you may choose not to exercise any of your Basic Subscription Rights. If you do not exercise your Basic Subscription Rights in full, you will not be entitled to exercise your Over-Subscription Privilege.

Additionally, sufficient Units may not be available to honor your Basic Subscription Right in full. While we are distributing one subscription right for every share of common stock owned or deemed owned on the record date, we are only seeking to raise $8 million dollars in gross proceeds in this Rights Offering. As a result, based on (1) 2,434,008 shares of common stock outstanding and (2) 456,891 shares of common stock deemed to be owned by holders of our Series B Preferred Stock and Participating Warrants and deemed to be outstanding as of December 2, 2019, we would grant subscription rights to acquire 2,890,899 Units but will only accept subscriptions for 8,000 Units.

If exercises of Basic Subscription Rights exceed the number of Units available in the Rights Offering, we will allocate the available Units pro-rata among the record holders exercising the Basic Subscription Rights in proportion to the number of shares of our common stock each of those record holders owned or were deemed to own on the record date, relative to the number of shares owned or deemed owned on the record date by all record holders exercising the basic subscription right. If this pro-rata allocation results in any record holders receiving a greater number of Units than the record holder subscribed for pursuant to the exercise of the basic subscription rights, then such record holder will be allocated only that number of Units for which the record holder subscribed, and the remaining Units will be allocated among all other record holders exercising their Basic Subscription Rights on the same pro rata basis described above. The proration process will be repeated until all shares have been allocated.

If for any reason the amount of Units allocated to you is less than you have subscribed for, then the excess funds held by the Subscription Agent on your behalf will be returned to you, without interest, as soon as practicable after the Rights Offering has expired and all prorating calculations and reductions contemplated by the terms of the Rights Offering have been effected, and we will have no further obligations to you.

Over-Subscription Privilege

If you exercise your Basic Subscription Rights in full, you may also choose to exercise your Over-Subscription Privilege. Subject to proration and the limitations described in this prospectus, we will seek to honor the Over-Subscription Requests in full. If Over-Subscription Requests exceed the number of Units available, however, we will allocate the available Units pro rata among the common and Series B stockholders and eligible warrant holders as of the Record Date exercising the Over-Subscription Privilege in proportion to the number of shares of our common stock (including each share of common stock issuable upon conversion of Series B Preferred Stock and exercise of Participating Warrants) each of those stockholders and/or warrant holders owned on the Record Date, relative to the number of shares owned on the Record Date by all stockholders and warrant holders as of the Record Date exercising the Over-Subscription Privilege. If this pro rata allocation results in any stockholder or warrant holder receiving a greater number of Units than the record holder subscribed for pursuant to the exercise of the Over-Subscription Privilege, then such record holder will be allocated only that number of Units for which the record holder oversubscribed, and the remaining Units will be allocated among all other stockholders or warrant holders exercising the Over-Subscription Privilege on the same pro rata basis described above. The proration process will be repeated until all Units have been allocated. American Stock Transfer & Trust Company, LLC, the Subscription Agent for the Rights Offering, will determine the over-subscription allocation based on the formula described above.

To the extent the aggregate subscription payment of the actual number of unsubscribed Units available to you pursuant to the Over-Subscription Privilege is less than the amount you actually paid in connection with the exercise of the Over-Subscription Privilege, you will be allocated only the number of unsubscribed Units available to you, and any excess subscription payments will be returned to you, without interest or deduction, with 10 business days after expiration of the Rights Offering.

We can provide no assurances that you will be entitled to purchase the number of Units issuable upon the exercise of your Over- Subscription Privilege in full at the expiration of the Rights Offering. We will not be able to satisfy any requests for Units pursuant to the Over-Subscription Privilege if all of our stockholders exercise their Basic Subscription Rights in full, and we will only honor an Over-Subscription Privilege to the extent sufficient Units are available following the exercise of Basic Subscription Rights.

Limitation on the Purchase of Units

You may only purchase the number of Units purchasable upon exercise of the number of Basic Subscription Rights distributed to you in the Rights Offering, plus the Over-Subscription Privilege, if any. Accordingly, the number of Units that you may purchase in the Rights Offering is limited by the number of shares of our common stock (including each share of common stock issuable upon conversion of Series B Preferred Stock and exercise of Participating Warrants) you held on the Record Date and by the extent to which other stockholders or warrant holders exercise their Basic Subscription Rights and Over-Subscription Privileges, all of which we cannot determine prior to completion of the Rights Offering. However, due to stock exchange restrictions, we will not issue Units in the Rights Offering to the extent that a holder would beneficially own, together with any other person with whom such holder’s securities may be aggregated under applicable law, more than 19.99% of our outstanding shares of common stock.

Subscription Price

The Subscription Price is $1,000 per Unit. The Subscription Price does not necessarily bear any relationship to our past or expected future results of operations, cash flows, current financial condition, or any other established criteria for value. No change will be made to the Subscription Price by reason of changes in the trading price of our common stock or other factor prior to the expiration of this Rights Offering.

Determination of Subscription Price

In the determining the Subscription Price, the board of directors considered a variety of factors including those listed below:

The Subscription Price does not necessarily bear any relationship to any established criteria for value. No valuation consultant or investment banker has opined upon the fairness or adequacy of the Subscription Price. You should not consider the Subscription Price as an indication of actual value of our company or our common stock. The market price of our common stock may decline during or after the Rights Offering. We cannot predict the price at which our shares of common stock will trade after the Rights Offering. You should obtain a current price quote for our common stock and perform an independent assessment of our Warrants before exercising your Subscription Rights and make your own assessment of our business and financial condition, our prospects for the future, and the terms of this Rights Offering. Once made, all exercises of Subscription Rights are irrevocable.

No Short-Sales

By exercising the Subscription Rights, you are representing to us that you have not entered into any short sale or similar transaction with respect to our common stock since the Record Date for the Rights Offering. In addition, the Subscription Rights provide that, upon exercise of the Subscription Right, you represent that you have not since the Record Date and, for so long as you continue to hold Preferred Stock or Warrants issued in connection with the exercise of the Subscription Right, agree to not to enter into any short sale or similar transaction with respect to our common stock. These requirements prevent you from pursuing certain investment strategies that could provide you greater financial benefits than you might have realized if the Subscription Rights did not contain these requirements.

No Recombination

The Preferred Stock and Warrants comprising the Units will separate upon the exercise of the Subscription Rights, and the Units will not trade as a separate security. Holders may not recombine shares of Preferred Stock and Warrants to receive a Unit.

Non-Transferability of Subscription Rights

The Subscription Rights are non-transferable (other than by operation of law) and, therefore, you may not sell, transfer, assign or give away your Subscription Rights to anyone. The Subscription Rights will not be listed for trading on any stock exchange or market.

Expiration Date; Extension

The subscription period, during which you may exercise your Subscription Rights, expires at 5:00 p.m., Eastern Time, on         ,          2019, which is the expiration of the Rights Offering. If you do not exercise your Subscription Rights before that time, your Subscription Rights will expire and will no longer be exercisable. We will not be required to issue shares to you if the Subscription Agent receives your Rights Certificate or your subscription payment after that time. We have the option to extend the Rights Offering in our sole discretion for any reason for up to an additional 45 days, although we do not presently intend to do so. We may extend the Rights Offering by giving oral or written notice to the Subscription Agent before the Rights Offering expires. If we elect to extend the Rights Offering, we will issue a press release announcing the extension no later than 9:00 a.m., Eastern Time, on the next business day after the most recently announced expiration date of the Rights Offering.

If you hold your shares of common stock, Series B Preferred Stock, or participating warrants in the name of a broker, dealer, bank or other nominee, the nominee will exercise the Subscription Rights on your behalf in accordance with your instructions. Please note that the nominee may establish a deadline that may be before 5:00 p.m., Eastern Time, on                 , 2019, which is the expiration date that we have established for the Rights Offering.

Termination

We may terminate the Rights Offering at any time and for any reason prior to the expiration of the Rights Offering. If we terminate the Rights Offering, we will issue a press release notifying stockholders and the public of the termination no later than 9:00 a.m., Eastern Time, on the next business day after the most recently announced expiration date of the Rights Offering.

Return of Funds upon Completion or Termination

The Subscription Agent will hold funds received in payment for shares in a segregated account pending completion of the Rights Offering. The Subscription Agent will hold this money until the Rights Offering is completed or is terminated. To the extent you properly exercise your Over-Subscription Privilege for an amount of Units that exceeds the number of unsubscribed Units available to you, any excess subscription payments will be returned to you within 10 business days after the expiration of the Rights Offering, without interest or deduction. If the Rights Offering is terminated for any reason, all subscription payments received by the Subscription Agent will be returned within 10 business days, without interest or deduction.

Shares of Our Capital Stock and Warrants Outstanding After the Rights Offering

Assuming no other transactions by us involving our capital stock prior to the expiration of the Rights Offering, and if the Rights Offering is fully subscribed, upon consummation of the Rights Offering we will have 2,434,008 shares of common stock issued and outstanding, 249 shares of Series B Preferred Stock issued and outstanding, 8,000 shares of Preferred Stock issued and outstanding, and               Warrants to purchase additional shares of our common stock issued and outstanding, based on 2,434,008 shares of our common stock outstanding as of October 25, 2019. The exact number of shares of Preferred Stock and Warrants that we will issue in this offering will depend on the number of Units that are subscribed for in the Rights Offering.

Methods for Exercising Subscription Rights

The exercise of Subscription Rights is irrevocable and may not be cancelled or modified. You may exercise your Subscription Rights as follows:

Subscription by Record Holders

If, as of the Record Date, you are a holder of record of common stock, Series B Preferred Stock or Participating Warrants, the number of Units you may purchase pursuant to your Subscription Rights is indicated on the enclosed Rights Certificate. You may exercise your Subscription Rights by properly completing and executing the Rights Certificate and forwarding it, together with your full payment, to the Subscription Agent at the address given below under “Subscription Agent,” to be received before 5:00 p.m., Eastern Time, on              , 2019.

Subscription by Beneficial Owners

If as of the Record Date you are a beneficial owner of shares of our common stock, Series B Preferred Stock or participating warrants that are registered in the name of a broker, dealer, bank or other nominee, you will not receive a Rights Certificate. Instead, we will issue one Subscription Right to such nominee record holder for all shares of our common stock, Series B Preferred Stock or participating warrants held by such nominee at the Record Date. If you are not contacted by your nominee, you should promptly contact your nominee in order to subscribe for shares in the Rights Offering and follow the instructions provided by your nominee.

To properly exercise your Over-Subscription Privilege, you must deliver the subscription payment related to your Over-Subscription Privilege before the Rights Offering expires. Because we will not know the total number of unsubscribed Units before the Rights Offering expires, if you wish to maximize the number of shares you purchase pursuant to your Over-Subscription Privilege, you will need to deliver payment in an amount equal to the aggregate subscription payment for the maximum number of Units that you wish to purchase.

Payment Method

Payments must be made in full in U.S. currency by personal check, certified check or bank draft, or by wire transfer, and payable to “American Stock Transfer and Trust Company, LLC, as Subscription Agent for SINTX Technologies, Inc.” You must timely pay the full subscription payment, including payment for the Over- Subscription Privilege, for the full number of shares of our common stock you wish to acquire pursuant to the exercise of Subscription Rights by delivering a:

If you elect to exercise your Subscription Rights, you should consider using a wire transfer or certified check drawn on a U.S. bank to ensure that the Subscription Agent receives your funds before the Rights Offering expires. If you send a personal check, payment will not be deemed to have been received by the Subscription Agent until the check has cleared. The clearinghouse may require five or more business days to clear a personal check. Accordingly, holders who wish to pay the Subscription Price by means of a personal check should make payment sufficiently in advance of the expiration of the Rights Offering to ensure that the payment is received and clears by that date. If you send a certified check, payment will be deemed to have been received by the Subscription Agent immediately upon receipt of such instrument.

You should read the instruction letter accompanying the Rights Certificate carefully and strictly follow it.DO NOT SEND RIGHTS CERTIFICATES OR PAYMENTS DIRECTLY TO US. We will not consider your subscription received until the Subscription Agent has received delivery of a properly completed and duly executed Rights Certificate and payment of the full subscription payment.

The method of delivery of Rights Certificates and payment of the subscription payment to the Subscription Agent will be at the risk of the holders of Subscription Rights. If sent by mail, we recommend that you send those certificates and payments by registered mail, properly insured, with return receipt requested, or by overnight courier, and that you allow a sufficient number of days to ensure delivery to the Subscription Agent and clearance of payment before the Rights Offering expires.

Missing or Incomplete Subscription Forms or Payment

If you fail to complete and sign the Rights Certificate or otherwise fail to follow the subscription procedures that apply to the exercise of your Subscription Rights before the Rights Offering expires, the Subscription Agent will reject your subscription or accept it to the extent of the payment received. Neither we nor our Subscription Agent undertakes any responsibility or action to contact you concerning an incomplete or incorrect subscription form, nor are we under any obligation to correct such forms. We have the sole discretion to determine whether a subscription exercise properly complies with the subscription procedures.

If you send a payment that is insufficient to purchase the number of shares you requested, or if the number of shares you requested is not specified in the forms, the payment received will be applied to exercise your Subscription Rights to the fullest extent possible based on the amount of the payment received. Any excess subscription payments received by the Subscription Agent will be returned, without interest or deduction, within 10 business days following the expiration of the Rights Offering.

Issuance of Preferred Stock and Warrants

The shares of Preferred Stock and Warrants that are purchased in the Rights Offering as part of the Units will be issued in book-entry, or uncertificated, form meaning that you will receive a DRS account statement from our transfer agent reflecting ownership of these securities if you are a holder of record. If you hold your shares of common stock, Series B Preferred Stock or participating warrants in the name of a bank, broker, dealer, or other nominee, DTC will credit your account with your nominee with the securities you purchased in the Rights Offering.

Subscription and Information Agent

The Subscription Agent for the Rights Offering is American Stock Transfer & Trust Company, LLC and the Information Agent is D.F. King & Co., Inc. The address to which Rights Certificates and payments should be mailed or delivered by overnight courier is provided below. If sent by mail, we recommend that you send documents and payments by registered mail, properly insured, with return receipt requested, and that you allow a sufficient number of days to ensure delivery to the Subscription Agent and clearance or payment before the Rights Offering expires. Do not send or deliver these materials to us.

If delivering by mail, hand or overnight courier:

American Stock Transfer & Trust Company, LLC

Operations Center

Attn: Reorganization Department

6201 15^th Avenue

Brooklyn, New York 11219

If you deliver the Rights Certificates in a manner different than that described in this prospectus, we may not honor the exercise of your Subscription Rights.

You should direct any questions or requests for assistance concerning the method of subscribing for the shares of our common stock or for additional copies of this prospectus to the Information Agent, D.F. King & Co., Inc., toll free at (866) 620-2536, or by mail at D.F. King & Co., Inc., 48 Wall Street, 22nd Floor, New York, NY 10005.

Warrant Agent

The warrant agent for the Warrants is American Stock Transfer & Trust Company, LLC.

No Fractional Shares

We will not issue fractional shares of common stock in the Rights Offering. We will only distribute Subscription Rights to acquire whole Units, rounded down to the nearest whole number of underlying common shares giving rise to such Subscription Rights. Any excess subscription payments received by the Subscription Agent will be returned within 10 business days after expiration of the Rights Offering, without interest or deduction. Similarly, no fractional shares of common stock will be issued in connection with the conversion of the Preferred Stock or the exercise of a Warrant. Instead, for any such fractional share that would otherwise have been issuable upon conversion of shares of Preferred Stock, the Company may, at its election, pay a cash payment equal to such fraction multiplied by the conversion price or round up to the next whole share, and for any such fractional share that would have otherwise been issued upon exercise of Warrants, the Company will round up such fraction to the next whole share.

Notice to Brokers and Nominees

If you are a broker, dealer, bank or other nominee holder that holds shares of our common stock, Series B Preferred Stock or participating warrants for the account of others on the Record Date, you should notify the beneficial owners for whom you are the nominee of the Rights Offering as soon as possible to learn their intentions with respect to exercising their Subscription Rights. If a beneficial owner of our common stock or participating warrant so instructs, you should complete the Rights Certificate and submit it to the Subscription Agent with the proper subscription payment by the expiration date. You may exercise the number of Subscription Rights to which all beneficial owners in the aggregate otherwise would have been entitled had they been direct holders of our common stock on the Record Date, provided that you, as a nominee record holder, make a proper showing to the Subscription Agent by submitting the form entitled “Nominee Holder Certification,” which is provided with your Rights Offering materials. If you did not receive this form, you should contact our Subscription Agent to request a copy.

Validity of Subscriptions

We will resolve all questions regarding the validity and form of the exercise of your Subscription Rights, including time of receipt and eligibility to participate in the Rights Offering. Our determination will be final and binding. Once made, subscriptions are irrevocable; we will not accept any alternative, conditional, or contingent subscriptions. We reserve the absolute right to reject any subscriptions not properly submitted or the acceptance of which would be unlawful. You must resolve any irregularities in connection with your subscriptions before the expiration date of the Rights Offering, unless we waive them in our sole discretion. Neither we nor the Subscription Agent is under any duty to notify you or your representative of defects in your subscriptions. A subscription will be considered accepted, subject to our right to withdraw or terminate the Rights Offering, only when the Subscription Agent receives a properly completed and duly executed Rights Certificate and any other required documents and the full subscription payment including final clearance of any personal check. Our interpretations of the terms and conditions of the Rights Offering will be final and binding.

Stockholder Rights

You will have no rights as a holder of the shares of our common stock issuable upon conversion of the Preferred Stock issued in the Rights Offering until such Preferred Stock is converted into common stock and issued in book-entry form or your account at your broker, dealer, bank or other nominee is credited with the shares of our common stock. Holders of Warrants issued in connection with the Rights Offering will not have rights as holders of our common stock until such Warrants are exercised and the shares of common stock underlying the Warrants are issued to the holder.

Foreign Stockholders

We will not mail this prospectus or Rights Certificates to stockholders with addresses that are outside the United States or that have an army post office or foreign post office address. The Subscription Agent will hold these Rights Certificates for their account. To exercise Subscription Rights, our foreign stockholders must notify the Subscription Agent prior to 5:00 p.m., Eastern Time, on            , 2019, the third business day prior to the expiration date, of your exercise of Subscription Rights and provide evidence satisfactory to us, such as a legal opinion from local counsel, that the exercise of such Subscription Rights does not violate the laws of the jurisdiction in which such stockholder resides and payment by a U.S. bank in U.S. dollars before the expiration of the offer. If no notice is received by such time or the evidence presented is not satisfactory to us, the Subscription Rights represented thereby will expire.

No Revocation or Change

Once you submit the Rights Certificate or have instructed your nominee of your subscription request, you are not allowed to revoke or change the exercise or request a refund of monies paid. All exercises of Subscription Rights are irrevocable, even if you learn information about us that you consider to be unfavorable. You should not exercise your Subscription Rights unless you are certain that you wish to purchase shares at the Subscription Price. If we should make any fundamental changes to the terms set forth in this prospectus, we will file a post-effective amendment to the registration statement in which this prospectus is included, offer potential purchasers who have subscribed for rights the opportunity to cancel such subscriptions and issue a refund of any money advanced by such stockholder or eligible warrant holder and recirculate an updated prospectus after the post-effective amendment is declared effective with the SEC.

U.S. Federal Income Tax Treatment of Rights Distribution

For U.S. federal income tax purposes, we do not believe holders of shares of our common stock, Series B Preferred Stock or participating warrants should recognize income or loss upon receipt or exercise of a Subscription Right. See “Material U.S. Federal Income Tax Consequences.”

No Recommendation to Rights Holders

Our board of directors is not making a recommendation regarding your exercise of the Subscription Rights. Stockholders who exercise Subscription Rights risk investment loss on money invested. We cannot predict the price at which our shares of common stock will trade after the Rights Offering. You should make your investment decision based on your assessment of our business and financial condition, our prospects for the future and the terms of this Rights Offering. Please see “Risk Factors” for a discussion of some of the risks involved in investing in our common stock.

Fees and Expenses

We will pay all fees charged by the Subscription Agent and the Information Agent, and by the dealer-manager. You are responsible for paying any other commissions, fees, taxes or other expenses incurred in connection with the exercise of your Subscription Rights.

Listing

The Subscription Rights may not be sold, transferred, assigned or given away to anyone, and will not be listed for trading on any stock exchange or market. There is no public trading market for the Preferred Stock or the Warrants and they will not be listed for trading on Nasdaq or any other securities exchange or market. The shares of our common stock issuable upon the conversion of the Preferred Stock and the exercise of the Warrants to be issued in the Rights Offering are traded on Nasdaq under the symbol “SINT.”

Important

Do not send Rights Certificates directly to us. You are responsible for choosing the payment and delivery method for your Rights Certificate and you bear the risks associated with such delivery. If you choose to deliver your Rights Certificate and payment by mail, we recommend that you use registered mail, properly insured, with return receipt requested. We also recommend that you allow a sufficient number of days to ensure delivery to the Subscription Agent and clearance of payment prior to the expiration time.

Distribution Arrangements

Maxim Group LLC will act as dealer-manager for the Rights Offering. The dealer-manager will provide marketing assistance and advice to us in connection with the Rights Offering and will use its best efforts to solicit the exercise of Subscription Rights and participation in the Over-Subscription Privilege. The dealer-manager is not underwriting or placing any of the Subscription Rights or the shares of our Preferred Stock or Warrants to be issued in the Rights Offering and does not make any recommendation with respect to such Subscription Rights (including with respect to the exercise or expiration of such Subscription Rights), shares or Warrants. We have agreed to pay the dealer-manager certain fees and to reimburse the dealer-manager for certain out-of-pocket expenses incurred in connection with this offering. See “Plan of Distribution.”

Other Matters

We are not making the rights offering in any state or other jurisdiction in which it is unlawful to do so, nor are we distributing or accepting any offers to purchase any units from subscription rights holders who are residents of those states or other jurisdictions or who are otherwise prohibited by federal or state laws or regulations from accepting or exercising the subscription rights. We may delay the commencement of the rights offering in those states or other jurisdictions, or change the terms of the rights offering, in whole or in part, in order to comply with the securities laws or other legal requirements of those states or other jurisdictions. Subject to state securities laws and regulations, we also have the discretion to delay allocation and distribution of any shares you may elect to purchase by exercise of your subscription privileges in order to comply with state securities laws. We may decline to make modifications to the terms of the rights offering requested by those states or other jurisdictions, in which case, if you are a resident in those states or jurisdictions or if you are otherwise prohibited by federal or state laws or regulations from accepting or exercising the subscription rights, you will not be eligible to participate in the rights offering. However, we are not currently aware of any states or jurisdictions that would preclude participation in the rights offering.

MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES

The following discussion describes the material U.S. federal income tax consequences of the receipt and exercise (or expiration) of the Subscription Rights acquired through the Rights Offering, the ownership and disposition of shares of our Preferred Stock and Warrants received upon exercise of the Subscription Rights and the ownership and disposition of the shares of common stock received upon the conversion of our Preferred Stock or the exercise of the Warrants. This discussion does not purport to be a complete analysis of all potential tax effects. The effects of other U.S. federal tax laws, such as estate and gift tax laws, and any applicable state, local or non-U.S. tax laws are not discussed. This discussion is based on the U.S. Internal Revenue Code of 1986, as amended, or the Code, U.S. Treasury Regulations promulgated thereunder, judicial decisions, and published rulings and administrative pronouncements of the U.S. Internal Revenue Service, or the IRS, in each case in effect as of the date hereof. These authorities may change or be subject to differing interpretations. Any such change or differing interpretation may be applied retroactively in a manner that could adversely affect a holder of the Subscription Rights, shares of our Preferred Stock, Warrants or shares of our common stock. We have not sought and will not seek any rulings from the IRS regarding the matters discussed below. There can be no assurance the IRS or a court will not take a contrary position to that discussed below regarding the tax consequences of the receipt of Subscription Rights through the Rights Offering by persons holding shares of our common stock and warrants entitled to receive Subscription Rights pursuant to this Rights Offering (which we refer to as participating warrants), the exercise (or expiration) of the Subscription Rights, the acquisition, ownership and disposition of shares of our Preferred Stock, and the acquisition, ownership and disposition (or expiration) of Warrants, each acquired upon exercise of the Subscription Rights, and the acquisition, ownership and disposition of shares of our common stock acquired upon conversion of our Preferred Stock or exercise of the Warrants.

This discussion is limited to the Subscription Rights acquired through the Rights Offering, shares of our Preferred Stock and Warrants acquired upon exercise of Subscription Rights and shares of our common stock acquired upon conversion of our Preferred Stock or exercise of the Warrants, in each case, that are held as a “capital asset” within the meaning of Section 1221 of the Code (generally, property held for investment). This discussion does not address all U.S. federal income tax consequences relevant to a holder’s particular circumstances, including the impact of the alternative minimum tax or the unearned income Medicare contribution tax. In addition, it does not address consequences relevant to holders subject to particular rules, including, without limitation:

If an entity treated as a partnership for U.S. federal income tax purposes holds shares of our common stock, the Subscription Rights, shares of our Preferred Stock and Warrants acquired upon exercise of Subscription Rights or shares of our common stock acquired upon conversion of our Preferred Stock or exercise of the Warrants, as the case may be, the tax treatment of a partner in the partnership will depend on the status of the partner, the activities of the partnership and certain determinations made at the partner level. Accordingly, partnerships and the partners in such partnerships should consult their tax advisors regarding the U.S. federal income tax consequences to them.

THISDISCUSSIONIS FOR INFORMATION PURPOSES ONLYANDISNOTTAXADVICE.INVESTORS SHOULDCONSULTTHEIR TAXADVISORS WITH RESPECT TO THE APPLICATION OF THEU.S. FEDERALINCOMETAX LAWS TO THEIR PARTICULAR SITUATIONSASWELLASANY TAX CONSEQUENCES OF THE RECEIPT, OWNERSHIPANDEXERCISE OF SUBSCRIPTION RIGHTS, THEACQUISITION,OWNERSHIP,ANDDISPOSITION OF SHARES OFOURPREFERRED STOCKANDWARRANTS ACQUIREDUPON EXERCISE OF SUBSCRIPTION RIGHTS,ANDSHARES OFOUR COMMON STOCKACQUIREDUPONCONVERSION OF PREFERRED STOCK OR EXERCISE OFWARRANTS ARISING UNDERTHEU.S.FEDERAL ESTATE OR GIFT TAX LAWS ORUNDERTHE LAWS OFANYSTATE, LOCAL ORNON-U.S.TAXING JURISDICTION ORUNDERANY APPLICABLEINCOME TAX TREATY.

Tax Considerations Applicable to U.S. Holders

Definition of a U.S. Holder

For purposes of this discussion, a “U.S. holder” is any beneficial owner of shares of our common stock, our Subscription Rights, shares of our Preferred Stock and Warrants acquired upon exercise of Subscription Rights or shares of our common stock acquired upon conversion of our Preferred Stock or exercise of Warrants, as the case may be, that, for U.S. federal income tax purposes, is:

Receipt of Subscription Rights

Although the authorities governing transactions such as this Rights Offering are complex and do not speak directly to the consequences of certain aspects of this Rights Offering, including the inclusion of the right to purchase Warrants in the Subscription Rights (rather than the right to purchase only shares of our Preferred Stock), the distribution of Subscription Rights to holders of participating warrants and the effects of the Over-Subscription Privilege, we do not believe a U.S. holder’s receipt of Subscription Rights pursuant to the Rights Offering should be treated as a taxable distribution with respect to its existing shares of common stock, Series B Preferred Stock or participating warrants, as applicable, for U.S. federal income tax purposes. Section 305(a) of the Code generally provides that the receipt by a stockholder, or a holder of rights to acquire stock, of a right to acquire stock or warrants is not included in the taxable income of the stockholder; however, the general non-recognition rule in Section 305(a) of the Code is subject to exceptions described in Section 305(b) of the Code, which include “disproportionate distributions.” A disproportionate distribution is generally a distribution or a series of distributions, including deemed distributions, that has the effect of the receipt of cash or other property by some stockholders (including holders of rights to acquire stock and holders of debt instruments convertible into stock) and an increase in the proportionate interest of other stockholders (including holders of rights to acquire stock and holders of debt instruments convertible into stock) in a corporation’s assets or earnings and profits.During the last 36 months, the Company has not made any distributions of cash or property (other than stock or rights to acquire stock) with respect to: (i) its common stock or (ii) options or warrants to acquire its common stock. Currently the Company does not intend to make any future distributions of cash or property (other than stock or rights to acquire stock) with respect to: (i) its common stock or (ii) options or warrants to acquire its common stock; however, there is no guarantee that the Company will not make such distributions in the future. In addition, the Company does not currently have any convertible debt outstanding nor does the Company currently intend to issue any convertible debt.

The position regarding the non-taxable treatment of the Subscription Right distribution is not binding on the IRS, or the courts. If this position is finally determined by the IRS or a court to be incorrect, whether because, contrary to our expectations, distributions of cash or property (other than stock or rights to acquire stock) are made with respect to our common stock, options or warrants, because the issuance of the Subscription Rights is a “disproportionate distribution” or otherwise, the fair market value of the Subscription Rights would be taxable to U.S. holders of our common stock as a dividend to the extent of the U.S. holder’s pro rata share of our current and accumulated earnings and profits, if any, with any excess being treated as a return of capital to the extent thereof and then as capital gain.Although no assurance can be given, the Company anticipates that it will not have current and accumulated earnings and profits through the end of 2019. Further, if the position regarding the non-taxable treatment of the Subscription Rights distribution is incorrect, the treatment of holders of participating warrants is not clear, and it may differ from, and may be more adverse than, the treatment of the Subscription Rights distribution to the holders of common stock.

The following discussion is based upon the treatment of the Subscription Right issuance as a non-taxable distribution with respect to a U.S. holder’s’ existing shares of common stock, Series B Preferred Stock or participating warrants for U.S. federal income tax purposes.

Tax Basis in the Subscription Rights

If the fair market value of the Subscription Rights a U.S. holder receives is less than 15% of the fair market value of the U.S. holder’s existing shares of common stock, Series B Preferred Stock or participating warrants (in each case, with respect to which the Subscription Rights are distributed) on the date the U.S. holder receives the Subscription Rights, the Subscription Rights will be allocated a zero tax basis for U.S. federal income tax purposes, unless the U.S. holder elects to allocate the tax basis in the holder’s existing shares of common stock, Series B Preferred Stock or participating warrants between the existing shares of common stock, Series B Preferred Stock or participating warrants and the Subscription Rights in proportion to the relative fair market values of the existing shares of common stock, Series B Preferred Stock or participating warrants and the Subscription Rights determined on the date of receipt of the Subscription Rights. If a U.S. holder chooses to allocate tax basis between the holder’s existing common shares or participating warrants and the Subscription Rights, the U.S. holder must make this election on a statement included with the holder’s timely filed U.S. federal income tax return (including extensions) for the taxable year in which the U.S. holder receives the Subscription Rights. Such an election is irrevocable.

However, if the fair market value of the Subscription Rights a U.S. holder receives is 15% or more of the fair market value of the holder’s existing shares of common stock, Series B Preferred Stock or participating warrants on the date the U.S. holder receives the Subscription Rights, then the U.S. holder must allocate tax basis in the existing shares of common stock, Series B Preferred Stock or participating warrants between those shares or warrants and the Subscription Rights the U.S. holder receives in proportion to their fair market values determined on the date the U.S. holder receives the Subscription Rights. Please refer to the discussion below regarding the U.S. tax treatment of a U.S. holder that, at the time of the receipt of the Subscription Right, no longer holds the common stock, Series B Preferred Stock or participating warrants with respect to which the Subscription Right was distributed.

The fair market value of the Subscription Rights on the date that the Subscription Rights are distributed is uncertain and the fair market value of the participating warrants is uncertain, and we have not obtained, and do not intend to obtain, an appraisal of the fair market value of the Subscription Rights or the participating warrants on that date. In determining the fair market value of the Subscription Rights, U.S. holders should consider all relevant facts and circumstances, including without limitation any difference between the Subscription Price of the Subscription Rights and the trading price of our shares of common stock on the date that the Subscription Rights are distributed, the fair market value and the conversion terms of the Preferred Stock, the exercise price of the Warrants, the length of the period during which the Subscription Rights may be exercised and the fact that the Subscription Rights are non-transferable. In determining the fair market value of the participating warrants, U.S. holders should consider all relevant facts and circumstances, including without limitation the difference between the exercise price of the participating warrants and the trading price of our common stock on the date that the Subscription Rights are distributed, the length of the period during which the participating warrants may be exercised, the nature of the adjustment provisions in the participating warrants that may affect the economics of the exercise of such participating warrants and any limitations of the transferability of the participating warrants.

Exercise of Subscription Rights

A U.S. holder will not recognize gain or loss upon the exercise of a Subscription Right received in the Rights Offering. A U.S. holder’s adjusted tax basis, if any, in the Subscription Right plus the Subscription Price should be allocated between the share of Preferred Stock and the Warrant acquired upon exercise of the Subscription Right. The tax basis in the common stock or participating warrants upon which the Subscription Rights were issued which is allocated to the Subscription Rights under the prior section entitled “—Tax Basis in the Subscription Rights” should be further allocated between the shares of Preferred Stock and the Warrant acquired upon exercise of the Subscription Right in proportion to their relative fair market values on the date the Subscription Rights were distributed. The Subscription Price should be allocated between the shares of Preferred Stock and the Warrant acquired upon exercise of the Subscription Right in proportion to their relative fair market values on the exercise date. These allocations will establish the U.S. holder’s initial tax basis for U.S. federal income tax purposes in the shares of Preferred Stock and Warrants received upon exercise of such U.S. holder’s Subscription Right. The holding period of a share of Preferred Stock or a Warrant acquired upon exercise of a Subscription Right in the Rights Offering will begin on the date of exercise.

If, at the time of the receipt or exercise of the Subscription Right, the U.S. holder no longer holds the common stock or participating warrant with respect to which the Subscription Right was distributed, then certain aspects of the tax treatment of the receipt and exercise of the Subscription Right are unclear, including (1) the allocation of the tax basis between the shares of our common stock, Series B Preferred Stock or participating warrants previously sold and the Subscription Right, (2) the impact of such allocation on the amount and timing of gain or loss recognized with respect to the shares of our common stock, Series B Preferred Stock or participating warrants previously sold, and (3) the impact of such allocation on the tax basis of the shares of our Preferred Stock and Warrants acquired upon exercise of the Subscription Right. If a U.S. holder exercises a Subscription Right received in the Rights Offering after disposing of shares of our common stock, Series B Preferred Stock or participating warrants with respect to which the Subscription Right is received, the U.S. holder should consult its own tax advisor.

Expiration of Subscription Rights

If a U.S. holder allows Subscription Rights received in the Rights Offering to expire, the U.S. holder should not recognize any gain or loss for U.S. federal income tax purposes, and the U.S. holder should re-allocate any portion of the tax basis in its existing common shares previously allocated to the Subscription Rights that have expired to such U.S. holder’s existing common shares.

Sale or Other Disposition, Exercise or Expiration of Warrants

Upon the sale or other taxable disposition of a Warrant (other than by exercise) received upon exercise of a Subscription Right, a U.S. holder will generally recognize capital gain or loss equal to the difference between the amount realized on the sale or other taxable disposition and the U.S. holder’s adjusted tax basis in the Warrant. A U.S. Holder’s adjusted tax basis in a Warrant will generally equal its initial tax basis (discussed above under “—Exercise of Subscription Rights”), as adjusted for any constructive dividends on the Warrant described below. This capital gain or loss will be long-term capital gain or loss if the U.S. holder’s holding period in such Warrant is more than one year at the time of the sale or other taxable disposition. The deductibility of capital losses is subject to certain limitations.

A U.S. holder will not be required to recognize income, gain or loss upon exercise of a Warrant received upon exercise of a Subscription Right. A U.S. holder’s tax basis in a share of our common stock received upon exercise of the Warrants for cash will be equal to the sum of (1) the U.S. holder’s tax basis in the Warrants exchanged therefor and (2) the exercise price of such Warrants. A U.S. holder’s holding period in the shares of our common stock received upon exercise will commence on the day after such U.S. holder exercises the Warrants.

In certain circumstances, the Warrants will be exercisable on a cashless basis. The U.S. federal income tax treatment of an exercise of a Warrant on a cashless basis is not clear, and could differ from the consequences described above. It is possible that a cashless exercise could be a taxable event. U.S. holders are urged to consult their tax advisors as to the consequences of an exercise of a Warrant on a cashless basis, including with respect to whether the exercise is a taxable event, and their holding period and tax basis in the common stock received.

If a Warrant expires without being exercised, a U.S. holder will recognize a capital loss in an amount equal to such holder’s adjusted tax basis in the Warrant. Such loss will be long-term capital loss if, at the time of the expiration, the U.S. holder’s holding period in such Warrant is more than one year. The deductibility of capital losses is subject to certain limitations.

Constructive Dividends on Warrants

As described in the section entitled “Dividend Policy,” we do not anticipate declaring or paying dividends to holders of our common stock or our Preferred Stock in the foreseeable future. However, if at any time during the period in which a U.S. holder holds Warrants received upon exercise of a Subscription Right, we were to pay a taxable dividend to our stockholders and, in accordance with the anti-dilution provisions of the Warrants, the exercise price of the Warrants were decreased, that decrease would be deemed to be the payment of a taxable dividend to a U.S. holder of the Warrants to the extent of our earnings and profits, notwithstanding the fact that such holder will not receive a cash payment. If the exercise price is adjusted in certain other circumstances (or in certain circumstances, there is a failure to make appropriate adjustments), or there is an adjustment to the number of common shares that will be issued on exercise of the Warrants, such adjustments may also result in the deemed payment of a taxable dividend to a U.S. holder. U.S. holders should consult their tax advisors regarding the proper treatment of any adjustments to the exercise price of the Warrants. We are currently required to report the amount of any deemed distributions to the IRS, as well as either on our website or to holders not exempt from reporting.

Distributions on Preferred Stock and Common Stock

As described in the section entitled “Dividend Policy,” we do not anticipate declaring or paying dividends to holders of our Preferred Stock, Series B Preferred Stock, or common stock in the foreseeable future. However, if we do make distributions of cash or property on our Preferred Stock, Series B Preferred Stock, or common stock, such distributions will constitute dividends to the extent paid out of our current or accumulated earnings and profits, as determined for U.S. federal income tax purposes. Dividends received by a corporate U.S. holder may be eligible for a dividends received deduction, subject to applicable limitations. Dividends received by certain non-corporate U.S. holders, including individuals, are generally taxed at the lower applicable capital gains rate provided certain holding period and other requirements are satisfied. Distributions in excess of our current and accumulated earnings and profits will constitute a return of capital and first be applied against and reduce a U.S. holder’s adjusted tax basis in its Preferred Stock or common stock, as the case may be, but not below zero. Any excess will be treated as capital gain and will be treated as described below in the section relating to the sale or disposition of our common stock.

Sale, Exchange or Other Disposition of Preferred Stock and Common Stock

Upon a sale, exchange, or other taxable disposition of our Preferred Stock (other than by conversion) or our common stock, a U.S. holder generally will recognize capital gain or loss equal to the difference between the amount realized (not including any amount attributable to declared and unpaid dividends, which will be taxable as described above to U.S. holders of record who have not previously included such dividends in income) and the U.S. holder’s adjusted tax basis in our Preferred Stock or our common stock. The U.S. holder’s adjusted tax basis in our Preferred Stock generally will equal its initial tax basis (discussed above under “—Exercise of Subscription Rights”), as adjusted for applicable distributions (including constructive dividends described below). A U.S. holder’s adjusted tax basis in our common stock generally will equal its initial tax basis in our common stock (discussed below under “—Conversion of the Preferred Stock into Our Common Stock”), as adjusted for applicable distributions (including constructive dividends described below). Such capital gain or loss generally will be long-term capital gain or loss if the U.S. holder’s holding period for our Preferred Stock or our common stock exceeded one year at the time of disposition (see the discussion below under “—Conversion of Our Preferred Stock into Our Common Stock” regarding a U.S. holder’s holding period for our common stock). Long-term capital gains recognized by certain non-corporate U.S. holders, including individuals, generally are subject to reduced rates of taxation. The deductibility of capital losses is subject to limitations.

Conversion of Our Preferred Stock into Our Common Stock

A U.S. holder will not recognize any gain or loss in respect of the receipt of our common stock upon the conversion of our Preferred Stock (except to the extent the U.S. holder receives a cash payment for any fractional share that would otherwise have been issuable upon conversion of the Preferred Stock). The adjusted tax basis of our common stock that a U.S. holder receives on conversion will equal the adjusted tax basis of the Preferred Stock converted (decreased by the adjusted tax basis allocable to any fractional share that would otherwise have been issuance upon conversion of the Preferred Stock), and the holding period of such common stock received on conversion will include the period during which the U.S. holder held the Preferred Stock prior to conversion.

In the event a U.S. holder’s Preferred Stock is converted pursuant to an election by such U.S. holder in the case of certain acquisitions or fundamental changes or pursuant to certain other transactions (including our consolidation or merger into another person), the tax treatment of such a conversion will depend upon the facts underlying the particular transaction triggering such a conversion. In this regard, it is possible that any related adjustments of the conversion rate would be treated as a constructive distribution to the U.S. holder as described below under “—Constructive Dividends on Preferred Stock.” U.S. holders should consult their own tax advisors to determine the specific tax treatment of a conversion under such circumstances.

Constructive Dividends on Preferred Stock

The conversion rate of our Preferred Stock is subject to adjustment under certain circumstances, as described above under “Description of Securities—Preferred Stock—Preferred Stock.” Section 305(c) of the Code and U.S. Treasury Regulations thereunder may treat a U.S. holder of our Preferred Stock as having received a constructive distribution includable in such U.S. holder’s income in the manner as described above under “—Distributions on Preferred Stock and Common Stock,” if and to the extent that certain adjustments in the conversion rate (or failures to make such an adjustment) increase the proportionate interest of such U.S. holder in our earnings and profits. In certain other circumstances, an adjustment to the conversion rate of our Preferred Stock or a failure to make such an adjustment could potentially give rise to constructive distributions to U.S. holders of our common stock. Thus, under certain circumstances, U.S. holders may recognize income in the event of a constructive distribution even though they may not receive any cash or property. We are currently required to report the amount of any deemed distributions to the IRS, as well as either on our website or to holders not exempt from reporting.

Information Reporting and Backup Withholding

A U.S. holder may be subject to information reporting and backup withholding when such holder receives dividend payments (including constructive dividends) or receives proceeds from the sale or other taxable disposition of the Warrants, shares of our Preferred Stock acquired through the exercise of Subscription Rights or shares of our common stock acquired through conversion of our Preferred Stock or exercise of the Warrants. Certain U.S. holders are exempt from backup withholding, including certain corporations and certain tax-exempt organizations. A U.S. holder will be subject to backup withholding if such holder is not otherwise exempt (or fails to properly establish an exemption) and such holder:

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit against a U.S. holder’s U.S. federal income tax liability, provided the required information is timely furnished to the IRS. U.S. holders should consult their tax advisors regarding their qualification for an exemption from backup withholding and the procedures for obtaining such an exemption.

Tax Considerations Applicable to Non-U.S. Holders

For purposes of this discussion, a “non-U.S. holder” is a beneficial owner of shares of our common stock, Series B Preferred Stock, participating warrants, our Subscription Rights, shares of our Preferred Stock and Warrants acquired upon exercise of Subscription Rights or shares of our common stock acquired upon conversion of our Preferred Stock or exercise of Warrants, as the case may be, that is neither a U.S. holder nor an entity treated as a partnership for U.S. federal income tax purposes.

Receipt, Exercise and Expiration of the Subscription Rights

The discussion assumes that the receipt of Subscription Rights will be treated as a nontaxable distribution. See “—Tax Considerations Applicable to U.S. Holders—Receipt of Subscription Rights” above. In such case, non-U.S. holders will not be subject to U.S. federal income tax (or any withholding thereof) on the receipt, exercise or expiration of the Subscription Rights.

Exercise of Warrants

A non-U.S. holder will not be subject to U.S. federal income tax on the cash exercise of Warrants into shares of our common stock. As discussed above in “—Tax Considerations Applicable to U.S. Holders—Sale or Other Disposition, Exercise or Expiration of Warrants,” the U.S. federal income tax treatment of an exercise of a Warrant on a cashless basis is not clear. Non-U.S. holders are urged to consult their tax advisors as to the consequences of an exercise of a Warrant on a cashless basis, including with respect to whether the exercise is a taxable event, and their holding period and tax basis in the common stock received.

Constructive Dividends on Warrants

As described in the section entitled “Dividend Policy,” we do not anticipate declaring or paying dividends to holders of our Preferred Stock or common stock in the foreseeable future. However, if at any time during the period in which a non-U.S. holder holds Warrants we were to pay a taxable dividend to our stockholders and, in accordance with the anti-dilution provisions of the Warrants, the exercise price of the Warrants were decreased, that decrease would be deemed to be the payment of a taxable dividend to a non-U.S. holder to the extent of our earnings and profits, notwithstanding the fact that such holder will not receive a cash payment. If the exercise price is adjusted in certain other circumstances (or in certain circumstances, there is a failure to make appropriate adjustments), or there is an adjustment to the number of common shares that will be issued on exercise of the Warrants, such adjustments may also result in the deemed payment of a taxable dividend to a non-U.S. holder. Any resulting withholding tax attributable to deemed dividends may be collected from other amounts payable or distributable to the non-U.S. holder. Non-U.S. holders should consult their tax advisors regarding the proper treatment of any adjustments to the Warrants.

Distributions on Preferred Stock and Common Stock

As described in the section entitled “Dividend Policy,” we do not anticipate declaring or paying dividends to holders of our Preferred Stock or common stock in the foreseeable future. However, if we do make distributions of cash or property on our Preferred Stock or common stock, such distributions will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. Amounts not treated as dividends for U.S. federal income tax purposes will constitute a return of capital and first be applied against and reduce a non-U.S. holder’s adjusted tax basis in its Preferred Stock or common stock, as the case may be, but not below zero. Any excess will be treated as capital gain and will be treated as described below in the section relating to the sale or disposition of our Preferred Stock, Warrants, or common stock. Because we may not know the extent to which a distribution is a dividend for U.S. federal income tax purposes at the time it is made, for purposes of the withholding rules discussed below we or the applicable withholding agent may treat the entire distribution as a dividend.

Subject to the discussion below on backup withholding and foreign accounts, dividends paid to a non-U.S. holder of our Preferred Stock or common stock that are not effectively connected with the non-U.S. holder’s conduct of a trade or business within the United States will be subject to U.S. federal withholding tax at a rate of 30% of the gross amount of the dividends (or such lower rate specified by an applicable income tax treaty).

Non-U.S. holders will be entitled to a reduction in or an exemption from withholding on dividends as a result of either (1) an applicable income tax treaty or (2) the non-U.S. holder holding our Preferred Stock or common stock in connection with the conduct of a trade or business within the United States and dividends being effectively connected with that trade or business. To claim such a reduction in or exemption from withholding, the non-U.S. holder must provide the applicable withholding agent with a properly executed (a) IRS Form W-8BEN or W-8BEN-E (or other applicable documentation) claiming an exemption from or reduction of the withholding tax under the benefit of an income tax treaty between the United States and the country in which the non-U.S. holder resides or is established, or (b) IRS Form W-8ECI stating that the dividends are not subject to withholding tax because they are effectively connected with the conduct by the non-U.S. holder of a trade or business within the United States, as may be applicable. These certifications must be provided to the applicable withholding agent prior to the payment of dividends and must be updated periodically. Non-U.S. holders that do not timely provide the applicable withholding agent with the required certification, but that qualify for a reduced rate under an applicable income tax treaty, may obtain a refund of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS.

If dividends paid to a non-U.S. holder are effectively connected with the non-U.S. holder’s conduct of a trade or business within the United States (and, if required by an applicable income tax treaty, the non-U.S. holder maintains a permanent establishment in the United States to which such dividends are attributable), then, although exempt from U.S. federal withholding tax (provided the non-U.S. holder provides appropriate certification, as described above, and subject to the discussion below on backup withholding and foreign accounts), the non-U.S. holder will be subject to U.S. federal income tax on such dividends on a net income basis at the regular graduated U.S. federal income tax rates. In addition, a non-U.S. holder that is a corporation may be subject to a branch profits tax at a rate of 30% (or such lower rate specified by an applicable income tax treaty) on its effectively connected earnings and profits for the taxable year that are attributable to such dividends, as adjusted for certain items. Non-U.S. holders should consult their tax advisors regarding their entitlement to benefits under any applicable income tax treaty.

Sale or Other Disposition of Preferred Stock, Warrants or Common Stock

Subject to the discussions below on backup withholding and foreign accounts, a non-U.S. holder will not be subject to U.S. federal income tax on any gain realized upon the sale or other taxable disposition of our Preferred Stock, Warrants or common stock unless:

Gain described in the first bullet point above generally will be subject to U.S. federal income tax on a net income basis at the regular graduated rates. A Non-U.S. holder that is a corporation also may be subject to a branch profits tax at a rate of 30% (or such lower rate specified by an applicable income tax treaty) on such effectively connected gain, as adjusted for certain items.

Gain described in the second bullet point above will be subject to U.S. federal income tax at a rate of 30% (or such lower rate specified by an applicable income tax treaty) on any gain derived from the disposition, which may be offset by U.S. source capital losses of the non-U.S. holder (even though the individual is not considered a resident of the United States), provided the non-U.S. holder has timely filed U.S. federal income tax returns with respect to such losses.

With respect to the third bullet point above, we believe we are not currently and do not anticipate becoming a USRPHC. Because the determination of whether we are a USRPHC depends on the fair market value of our USRPIs relative to the fair market value of our other business assets and our non-U.S. real property interests, however, there can be no assurance we are not a USRPHC or will not become one in the future.

Non-U.S. holders should consult their tax advisors regarding potentially applicable income tax treaties that may provide for different rules.

Conversion of Our Preferred Stock into Our Common Stock

A non-U.S. holder will not recognize any gain or loss in respect of the receipt of our common stock upon the conversion of our Preferred Stock (except to the extent the non-U.S. holder receives a cash payment for any fractional share that would otherwise have been issuable upon conversion of the Preferred Stock).

Constructive Dividends on Preferred Stock

As described above under “—Tax Considerations Applicable to U.S. Holders—Constructive Dividends on Preferred Stock,” in certain circumstances, a non-U.S. holder will be deemed to receive a constructive distribution from us. Adjustments in the conversion rate (or failures to adjust the conversion rate) that increase the proportionate interest of a non-U.S. holder in our earnings and profits could result in deemed distributions to the non-U.S. holder that are treated as dividends for U.S. federal income tax purposes. Any constructive dividend deemed paid to a non-U.S. holder will be subject to U.S. federal income tax or withholding tax in the manner described above under “—Tax Considerations Applicable to Non-U.S. Holders—Distributions on Preferred Stock and Common Stock.” It is possible that U.S. federal tax on the constructive dividend would be withheld, if applicable, from subsequent payments on the Preferred Stock or our common stock.

Information Reporting and Backup Withholding

Subject to the discussion below on foreign accounts, a non-U.S. holder will not be subject to backup withholding with respect to distributions on our Preferred Stock, Warrants or common stock we make to the non-U.S. holder, provided the applicable withholding agent does not have actual knowledge or reason to know such holder is a United States person and the holder timely certifies its non-U.S. status, such as by providing a valid IRS Form W-8BEN, W- 8BEN-E or W-8ECI, or other applicable certification. However, information returns generally will be filed with the IRS in connection with any distributions (including deemed distributions) made on our Preferred Stock, Warrants and common stock to the non-U.S. holder, regardless of whether any tax was actually withheld. Copies of these information returns may also be made available under the provisions of a specific treaty or agreement to the tax authorities of the country in which the non-U.S. holder resides or is established.

Information reporting and backup withholding may apply to the proceeds of a sale or other taxable disposition of our Preferred Stock, Warrants or common stock within the United States, and information reporting may (although backup withholding generally will not) apply to the proceeds of a sale or other taxable disposition of our Preferred Stock, Warrants or common stock outside the United States conducted through certain U.S.-related financial intermediaries, in each case, unless the beneficial owner timely certifies under penalty of perjury that it is a non-U.S. holder on IRS Form W-8BEN or W-8BEN-E, or other applicable form (and the payor does not have actual knowledge or reason to know that the beneficial owner is a U.S. person) or such owner otherwise timely establishes an exemption. Proceeds of a disposition of our Preferred Stock, Warrants or common stock conducted through a non-U.S. office of a non-U.S. broker generally will not be subject to backup withholding or information reporting.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit against a non-U.S. holder’s U.S. federal income tax liability, provided the required information is timely furnished to the IRS.

Additional Withholding Tax on Payments Made to Foreign Accounts

Withholding taxes may be imposed under the Foreign Account Tax Compliance Act, or FATCA, on certain types of payments made to non-U.S. financial institutions and certain other non-U.S. entities. Specifically, a 30% withholding tax may be imposed on dividends (including deemed dividends) paid on our Preferred Stock, Warrants or common stock, or gross proceeds from the sale or other disposition of our Preferred Stock, Warrants or common stock paid to a “foreign financial institution” or a “non-financial foreign entity” (each as defined in the Code), unless (1) the foreign financial institution undertakes certain diligence and reporting obligations, (2) the non-financial foreign entity either certifies it does not have any “substantial United States owners” (as defined in the Code) or furnishes identifying information regarding each substantial United States owner, or (3) the foreign financial institution or non-financial foreign entity otherwise qualifies for an exemption from these rules. If the payee is a foreign financial institution and is subject to the diligence and reporting requirements in (1) above, it must enter into an agreement with the U.S. Department of the Treasury requiring, among other things, that it undertake to identify accounts held by certain “specified United States persons” or “United States-owned foreign entities” (each as defined in the Code), annually report certain information about such accounts, and withhold 30% on certain payments to non-compliant foreign financial institutions and certain other account holders. Foreign financial institutions located in jurisdictions that have an intergovernmental agreement with the United States governing FATCA may be subject to different rules.

Under the applicable U.S. Treasury Regulations and administrative guidance, withholding under FATCA generally applies to payments of dividends (including deemed dividends), and will apply to payments of gross proceeds (including a distribution to the extent it is treated as a return of capital or capital gain) from the sale or other disposition of our Preferred Stock, Warrants or common stock on or after January 1, 2019. Pursuant to Treasury Regulations proposed under Sections 1471 through 1474 of the Code, the U.S. Treasury Department and the IRS have proposed to eliminate the application of the FATCA withholding rules to gross proceeds from the sale or other disposition of any property of a type which can produce interest or dividends from U.S. sources. Under Section 7805(b)(1)(C) of the Code, taxpayers may rely on such proposed Treasury Regulations until final Treasury Regulations are issued. Because we may not know the extent to which a distribution is a dividend for U.S. federal income tax purposes at the time it is made, for purposes of these withholding rules we or the applicable withholding agent may treat the entire distribution as a dividend. Prospective investors should consult their tax advisors regarding the potential application of these withholding provisions.

DESCRIPTION OF SECURITIES

As of the date of this prospectus, our Restated Certificate of Incorporation authorizes us to issue 250,000,000 shares of common stock, par value $0.01 per share, and 130,000,000 shares of preferred stock, par value $0.01 per share. The following is a summary of the rights of our common and preferred stock and some of the provisions of our Restated Certificate of Incorporation and Restated Bylaws, our outstanding warrants, our registration rights agreements and the Delaware General Corporation Law. Because it is only a summary, it does not contain all the information that may be important to you and is subject to and qualified in its entirety by our Restated Certificate of Incorporation and our Restated Bylaws, a copy of each of which has been incorporated as an exhibit to the registration statement of which this prospectus forms a part.

Our Restated Certificate of Incorporation and our Restated Bylaws contain certain provisions that are intended to enhance the likelihood of continuity and stability in the composition of the boardBoard of directors,Directors, which may have the effect of delaying, deferring or preventing a future takeover or change in control of the Company unless such takeover or change in control is approved by our boardBoard of directors.Directors.

Common Stock

As of September 30, 2019,29, 2023, there were 2,363,9914,208,151 shares of common stock outstanding. In addition, as of September 30, 2019 there were: (i) 377 shares of common stock subject to outstanding options; (ii) 5,953 shares of common stock reserved for future issuance under our Amended and Restated 2012 Equity Incentive Plan; (iii) 391,319 shares of common stock reserved for future issuance under outstanding common stock warrants; and (iv) 114,762 shares of common stock reserved for issuance on conversion of 249 shares of the Series B Preferred Stock. Each outstanding share of common stock entitles the holder thereof to one vote per share on all matters. Our Restated Bylaws provide that any vacancy occurring in the boardBoard of directorsDirectors may be filled by the affirmative vote of a majority of the remaining directors. StockholdersHolders of our common stock do not have preemptive rights to purchase shares in any future issuance of our common stock. In the event of our liquidation, dissolution or winding up, holders of our common stock are entitled to receive, ratably, the net assets available to stockholders after payment of all creditors.

Holders of our common stock are entitled to one vote for each share held of record on all matters submitted to a vote of the stockholders, and do not have cumulative voting rights. Accordingly, the holders of a majority of the shares of our common stock entitled to vote can elect all of the directors standing for election. Subject to preferences that may be applicable to any outstanding shares of preferred stock, holders of our common stock are entitled to receive ratably such dividends, if any, as may be declared from time to time by our boardBoard of directorsDirectors out of funds legally available for dividend payments. All outstanding shares of our common stock are fully paid and nonassessable, and any shares of our common stock to be sold pursuant to this prospectus will be fully paid and nonassessable. The holders of common stock have no preferences or rights of conversion, exchange, pre- emptionpre-emption, or other subscription rights. There are no redemption or sinking fund provisions applicable to our common stock. In the event of any liquidation, dissolution or winding-up of our affairs, holders of our common stock will be entitled to share ratably in our assets that are remaining after payment or provision for payment of all of our debts and obligations and after liquidation payments to holders of outstanding shares of preferred stock, if any.

The transfer agent and registrar for our common stock is American Stock Transfer and Trust Company. The transfer agent and the registrar’s address is 59 Maiden Lane, New York, New York 10038. Their telephone number is 1-800-937-5449. Our common stock is listed on The NASDAQNasdaq Capital Market under the symbol “SINT”.

Description of Securities Included in this Offering

We are offering Units, each Unit consisting of one share of common stock and one Class E Warrant to purchase one share of common stock.

We are offering to each purchaser whose purchase of shares of common stock in this offering would otherwise result in the purchaser, together with its affiliates, beneficially owning more than 4.99% (or, at the election of the holder, 9.99%) of our outstanding shares of common stock immediately following the consummation of this offering, the opportunity to purchase, if the purchaser so chooses, Units containing pre-funded warrants, in lieu of shares of common stock that would otherwise result in the purchaser’s beneficial ownership exceeding 4.99% (or, at the election of the holder, 9.99%) of our outstanding shares of common stock. For each pre-funded warrant we sell (without regard to any limitation on exercise set forth therein), the number of shares of common stock we are offering will be decreased on a one-for-one basis. Because one Class E Warrant is being sold together in this offering with each share of common stock or, in the alternative, each pre-funded warrant to purchase one share of common stock, the number of Class E Warrants sold in this offering will not change as a result of a change in the mix of the shares of common stock and pre-funded warrants sold.

We are also registering the shares of common stock issuable from time to time upon exercise of the Class E Warrants, and pre-funded warrants included in the Units offered hereby. Our Units have no stand-alone rights and will not be certificated or issued as stand-alone securities. The shares of common stock (or pre-funded warrants) and Class E Warrants comprising our Units are immediately separable and will be issued separately in this offering.

The following summary of certain terms and provisions of the pre-funded warrants and Class E Warrants offered hereby is not complete and is subject to, and qualified in its entirety by the provisions of the form of pre-funded warrant, and the form of Class E Warrant, which are filed as exhibits to the registration statement of which this prospectus forms a part. Prospective investors should carefully review the terms and provisions set forth in the form of Class E Warrant and form of pre-funded warrant.

Exercisability. The pre-funded warrants are exercisable at any time after their original issuance until they are exercised in full. The Class E Warrants are exercisable at any time after their original issuance and at any time up to the date that is            years after their original issuance. Each of the Class E Warrants and the pre-funded warrants will be exercisable, at the option of each holder, in whole or in part by delivering to us a duly executed exercise notice and, at any time a registration statement registering the issuance of the shares of common stock underlying the Class E Warrants, under the Securities Act of 1933, as amended (the “Securities Act”) is effective and available for the issuance of such shares, by payment in full in immediately available funds for the number of shares of common stock purchased upon such exercise. If a registration statement registering the issuance of the shares of common stock underlying the Class E Warrants or pre-funded warrants under the Securities Act is not effective or available, the holder may, in its sole discretion, elect to exercise the Class E Warrant or pre-funded warrant through a cashless exercise, in which case the holder would receive upon such exercise the net number of shares of common stock determined according to the formula set forth in the warrant. We may be required to pay certain amounts as liquidated damages as specified in the warrants in the event we do not deliver shares of common stock upon exercise of the warrants within the time periods specified in the warrants. No fractional shares of common stock will be issued in connection with the exercise of a warrant.

Exercise Limitation. A holder will not have the right to exercise any portion of the pre-funded warrants, or Class E Warrants if the holder (together with its affiliates) would beneficially own in excess of 4.99% (or, upon election by a holder prior to the issuance of any warrants, 9.99%) of the number of shares of our common stock outstanding immediately after giving effect to the exercise, as such percentage ownership is determined in accordance with the terms of the warrants. However, any holder may increase or decrease such percentage to any other percentage not in excess of 9.99%, upon at least 61 days’ prior notice from the holder to us with respect to any increase in such percentage.

Exercise Price. The exercise price for the pre-funded warrants is $0.0001 per share. The exercise price per whole share of common stock purchasable upon exercise of the Class E Warrants is $          per share. The exercise price and number of shares of common stock issuable on exercise are subject to appropriate adjustments in the event of certain stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting our common stock.

Transferability. Subject to applicable laws, the Class E Warrants and pre-funded warrants may be offered for sale, sold, transferred or assigned without our consent.

Exchange Listing. We do not intend to list the Class E Warrants or the pre-funded warrants offered in this offering on any securities exchange or other trading market. Without an active trading market, the liquidity of these securities will be limited.

Warrant Agent. The pre-funded warrants and Class E Warrants are expected to be issued in registered form under a warrant agreement between American Stock Transfer & Trust Company, LLC, as warrant agent, and us. The Class E Warrants and the pre-funded warrants shall initially be represented only by one or more global warrants deposited with the warrant agent, as custodian on behalf of The Depository Trust Company (DTC) and registered in the name of Cede & Co., a nominee of DTC, or as otherwise directed by DTC.

Fundamental Transactions. In the event of a fundamental transaction, as described in the Class E Warrants and pre-funded warrants and generally including, with certain exceptions, any reorganization, recapitalization or reclassification of our common stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding shares of common stock, or any person or group becoming the beneficial owner of 50% of the voting power represented by our outstanding shares of common stock, the holders of the Class E Warrants and pre-funded warrants will be entitled to receive upon exercise of the warrants the kind and amount of securities, cash or other property that the holders would have received had they exercised the warrants immediately prior to such fundamental transaction. In addition, in the event of a fundamental transaction, we or the successor entity, at the request of a holder of Class E Warrants, will be obligated to purchase any unexercised portion of such Class E Warrants in accordance with the terms of the Class E Warrants. Additionally, as more fully described in the Class E Warrants, in the event of certain fundamental transactions, the holders of the Class E Warrants will be entitled to receive consideration in an amount equal to the Black Scholes value of the Class E Warrants on the date of consummation of such transaction.

Rights as a Shareholder. Except as otherwise provided in the Class E Warrants or pre-funded warrants or by virtue of such holder’s ownership of our shares of common stock, the holder of a Class E Warrant or pre-funded warrant does not have the rights or privileges of a holder of our common stock, including any voting rights, until the holder exercises the warrant. Holders of pre-funded warrants have the right to participate in dividends and certain distributions as specified in the warrant.

Governing Law. The pre-funded warrants, Class E Warrants, and warrant agreement are governed by New York law.

Description of Other Outstanding Securities of the Company

Preferred Stock

Our Board of directorsDirectors has the authority under our Restated Certificate of Incorporation, without further action by our stockholders, to issue up to 130,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the rights, preferences, privileges and restrictions of the shares of each wholly unissued series, including dividend rights, conversion rights, voting rights, terms of redemption, liquidation preference and sinking fund terms, and to increase or decrease the number of shares of any such series (but not below the number of shares of such series then outstanding).

Our boardBoard of directorsDirectors may authorize the issuance of preferred stock with voting or conversion rights that could have the effect of restricting dividends on our common stock, diluting the voting power of our common stock, impairing the liquidation rights of our common stock or otherwise adversely affecting the rights of holders of our common stock. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions and other corporate purposes, could, among other things, have the effect of delaying, deferring or preventing a change of control and may adversely affect the market price of our common stock.

Series B Preferred Stock.

Our boardBoard of directorsDirectors designated 15,000 shares of our preferred stock as Series B Preferred Stock. As of September 30, 2019,29, 2023, there were 24926 shares of Series B Preferred stock outstanding. The Series B Preferred Stock ranks senior tooutstanding which are convertible into 10,576 shares of our common stock and other classes of capital stock with respect to redemption, unless the holders of a majority of the outstanding shares of Series B Preferred Stock consent to the creation of parity stock or senior preferred stock.

Conversion

Each share of Series B Preferred Stock is convertible into shares of our common stock at any time at the holder’s option at the Conversion Price described below. We may not effect any conversion of Series B Preferred Stock, with certain exceptions, to the extent that, after giving effect to an attempted conversion, the holder of Series B Preferred Stock (together with such holder’s affiliates, and any persons acting as a group together with such holder or any of such holder’s affiliates) would beneficially own a number of shares of common stock in excess of 4.99% (or, at the election of the holder, 9.99%) of the shares of our common stock then outstanding after giving effect to such conversion, referred to as the Preferred Stock Beneficial Ownership Limitation; provided, however, that upon notice to the Company,us, the holder may increase or decrease the Preferred Stock Beneficial Ownership Limitation, provided that in no event may the Preferred Stock Beneficial Ownership Limitation exceed 9.99% and any increase in the Preferred Stock Beneficial Ownership Limitation will not be effective until 61 days following notice of such increase from the holder to us.

Subject to certain ownership limitations as described below and certain equity conditions being met, if during any 30 consecutive trading days, the volume weighted average price of our common stock exceeds $130.61$13,060.80 and the daily dollar trading volume during such period exceeds $500,000 per trading day, we have the right to force the conversion of the Series B Preferred Stock into common stock.

Conversion Price.

The Series B Preferred Stock is convertible into shares of common stock by dividing the stated value of the Series B Preferred Stock ($1,100) by $2.3867$2.70 (the “Conversion Price”). The Conversion Price is subject to adjustment for stock splits, stock dividends, and distributions of common stock or securities convertible, exercisable or exchangeable for common stock, subdivisions, combinations and reclassifications.

Subject to certain exclusions contained in the Certificate of Designation, if the Companywe in any manner grantsgrant or sellssell any rights, warrants or options and the lowest price per share for which one share of common stock is at any time issuable upon the exercise of any such option or upon conversion, exercise or exchange of any Common Stock Equivalents (as defined in the Certificate of Designation) issuable upon exercise of any such option, exercise or exchange of any Common Stock Equivalent issuable upon the exercise of such option or otherwise pursuant to the terms thereof is less than the Conversion Price, then such share of common stock will be deemed to be outstanding and to have been issued and sold by the Companyus at the time of the granting or sale of such option for such price per share. For purposes of this paragraph only, the “lowest price per share for which one share of common stock is issuable upon the exercise of any such options or upon conversion, exercise or exchange of any Common Stock Equivalent issuable upon exercise of any such option or otherwise pursuant to the terms thereof” will be equal to (1) the lower of  (x) the sum of the lowest amounts of consideration (if any) received or receivable by the Companyus with respect to any one share of common stock upon the granting or sale of such option, upon exercise of such option and upon conversion, exercise or exchange of any Common Stock Equivalents issuable upon exercise of such option or otherwise pursuant to the terms thereof and (y) the lowest exercise price set forth in such option for which one share of common stock is issuable upon the exercise of any such options or upon conversion, exercise or exchange of any Common Stock Equivalents issuable upon exercise of any such option or otherwise pursuant to the terms thereof. Except as contemplated by the terms of the Certificate of Designation, no further adjustment of the Conversion Price will be made upon the actual issuance of such shares of common stock or of such convertible securities upon the exercise of such options or otherwise pursuant to the terms of or upon the actual issuance of such Common Stock Equivalents.

Subject to certain exclusions contained in the Certificate of Designation, if the Companywe in any manner issuesissue or sellssell any Common Stock Equivalents and the lowest price per share for which one share of common stock is at any time issuable upon the conversion, exercise or exchange thereof or otherwise pursuant to the terms thereof is less than the Conversion Price, then such share of common stock will be deemed to be outstanding and to have been issued and sold by the Companyus at the time of the issuance or sale of such convertible securities for such price per share. For purposes of this paragraph only, the “lowest price per share for which one share of common stock is issuable upon the conversion, exercise or exchange thereof or otherwise pursuant to the terms thereof” will be equal to (1) the lower of  (x) the sum of the lowest amounts of consideration (if any) received or receivable by the Companyus with respect to one share of common stock upon the issuance or sale of the Common Stock Equivalent and upon conversion, exercise or exchange of such convertible security or otherwise pursuant to the terms thereof and (y) the lowest conversion price set forth in such convertible security for which one share of common stock is issuable upon conversion, exercise or exchange thereof or otherwise pursuant to the terms thereof minus (2) the sum of all amounts paid or payable to the holder of such Common Stock Equivalent (or any other person) upon the issuance or sale of such Common Stock Equivalent plus the value of any other consideration received or receivable by, or benefit conferred on, the holder of such Common Stock Equivalent (or any other person). Except as contemplated by the terms of the Certificate of Designation, no further adjustment of the Conversion Price will be made upon the actual issuance of such shares of common stock upon conversion, exercise or exchange of such Common Stock Equivalents or otherwise pursuant to the terms thereof, and if any such issuance or sale of such Common Stock Equivalents is made upon exercise of any options for which adjustment of the Conversion Price has been or is to be made, except as contemplated by the terms of the Certificate of Designation, no further adjustment of the Conversion Price will be made by reason of such issuance or sale.

If the purchase or exercise price provided for in any options, the additional consideration, if any, payable upon the issue, conversion, exercise or exchange of any convertible securities, or the rate at which any convertible securities are convertible into or exercisable or exchangeable for shares of common stock increases or decreases at any time (other than proportional changes in conversion or exercise prices, as applicable, in connection with stock dividends, splits or combination of outstanding common stock) the Conversion Price in effect at the time of such increase or decrease will be adjusted to the Conversion Price which would have been in effect at such time had such options or convertible securities provided for such increased or decreased purchase price, additional consideration or increased or decreased conversion rate, as the case may be, at the time initially granted, issued or sold. If the terms of any option or convertible security that was outstanding as of the date of issuance of the Preferred Stock and related Warrants are increased or decreased in the manner described in the immediately preceding sentence, then such option or convertible security and the shares of common stock deemed issuable upon exercise, conversion or exchange thereof will be deemed to have been issued as of the date of such increase or decrease. No adjustment will be made if such adjustment would result in an increase of the Conversion Price then in effect.

If any option and/or convertible security and/or Adjustment Right is issued in connection with the issuance or sale or deemed issuance or sale of any other securities of the Company (as determined by the holder of Preferred Stock, the “Primary Security”, and such option and/or convertible security and/or Adjustment Right (as defined below), the “Secondary Securities” and together with the Primary Security, each a “unit”), together comprising one integrated transaction, the aggregate consideration per share of common stock with respect to such Primary Security will be deemed to be the lower of  (x) the purchase price of such unit, (y) if such Primary Security is an option and/or convertible security, the lowest price per share for which one share of common stock is at any time issuable upon the exercise or conversion of the Primary Security in accordance with the paragraphs above and (z) the lowest volume-weighted average price of the common stock on any trading day during the four trading day period immediately following the public announcement of such dilutive issuance. If any shares of common stock, options or convertible securities are issued or sold or deemed to have been issued or sold for cash, the consideration received therefor will be deemed to be the net amount of consideration received by the Companyus therefor. If any shares of common stock, options or convertible securities are issued or sold for a consideration other than cash, the amount of such consideration received by the Companyus will be the fair value of such consideration, except where such consideration consists of publicly traded securities, in which case the amount of consideration received by the Companyus for such securities will be the arithmetic average of the volume-weighted average prices of such security for each of the five (5) trading days immediately preceding the date of receipt. If any shares of common stock, options or convertible securities are issued to the owners of the non-surviving entity in connection with any merger in which the Company iswe are the surviving entity, the amount of consideration therefor will be deemed to be the fair value of such portion of the net assets and business of the non-surviving entity as is attributable to such shares of common stock, options or convertible securities (as the case may be). The fair value of any consideration other than cash or publicly traded securities will be determined jointly by the Companyus and the holder. If such parties are unable to reach agreement within ten (10) days after the occurrence of an event requiring valuation (the “Valuation Event”), the fair value of such consideration will be determined within five trading days after the tenth day following such Valuation Event by an independent, reputable appraiser jointly selected by the Companyus and the holder. “Adjustment

“Adjustment Right” means any right granted with respect to any securities issued in connection with, or with respect to, any issuance or sale (or deemed issuance or sale in accordance with the paragraph above) of shares of common stock that could result in a decrease in the net consideration received by the Companyus in connection with, or with respect to, such securities (including, without limitation, any cash settlement rights, cash adjustment or other similar rights).

In addition, holders of Series B Preferred Stock may be eligible to elect an alternative price in the event we issue certain variable price securities.

Liquidation; Dividends; Repurchases.

In the event of a liquidation, the holders of Series B Preferred Stock are entitled to participate on an as-converted-to-common stock basis with holders of the common stock in any distribution of assets of the Company to the holders of the common stock. Additionally, we will not pay any dividends on shares of common stock (other than dividends in the form of common stock) unless and until such time as we pay dividends on each Series B Preferred Share on an as-converted basis. Other than as set forth in the previous sentence, no other dividends will be paid on Series B Preferred Stock and we will pay no dividends (other than dividends in the form of common stock) on shares of common stock unless we simultaneously comply with the previous sentence.

Redemption Right.

The Company holdsWe hold an option to redeem some or all of the Series B Preferred Stock at any time after the six-month anniversary of its issuance date at a 25% premium to the stated value of the Series B Preferred Stock subject to redemption, upon 30 days prior written notice to the holder of the Series B Preferred Stock. The Series B Preferred Stock would be redeemed by the Companyus for cash.

Fundamental Transactions.

In the event of any fundamental transaction, generally including any merger with or into another entity, sale of all or substantially all of our assets, tender offer or exchange offer, or reclassification of our common stock, then upon any subsequent conversion of the Series B Preferred Stock, the holder will have the right to receive as alternative consideration, for each share of our common stock that would have been issuable upon such conversion immediately prior to the occurrence of such fundamental transaction, the number of shares of common stock of the successor or acquiring corporation or of our company, if it is the surviving corporation, and any additional consideration receivable upon or as a result of such transaction by a holder of the number of shares of our common stock for which the Series B Preferred Stock is convertible immediately prior to such event.

Voting Rights.

With certain exceptions, the holders of shares of Series B Preferred Stock have no voting rights. However, as long as any shares of Series B Preferred Stock remain outstanding, we may not, without the affirmative vote of holders of a majority of the then-outstanding Series B Preferred Stock, (a) alter or change adversely the powers, preferences or rights given to the Series B Preferred Stock or alter or amend the Certificate of Designation, (b) increase the number of authorized shares of Series B Preferred Stock, (c) amend our Certificate of Incorporation or other charter documents in any manner that adversely affects any rights of holders of Series B Preferred Stock disproportionately to the rights of holders of our other capital stock, or (d) enter into any agreement with respect to any of the foregoing.

Jurisdiction and Waiver of Trial by Jury

Other than with respect to suits, actions or proceedings arising under the federal securities laws, the Certificate of Designation provides for investors to consent to exclusive jurisdiction to courts located in New York, New York and provides for a waiver of the right to a trial by jury. It also provides that disputes are governed by Delaware law.

Series C Preferred Stock.

Our Board of Directors designated 9,440 shares of our preferred stock as Series C Preferred Stock. As of September 29, 2023, there were 50 shares of Series C Preferred stock outstanding which are convertible into 338 shares of our common stock.

Conversion. Each share of Series C Preferred Stock will be convertible at our option at any time on or after the first anniversary of the expiration of the Rights Offering or at the option of the holder at any time, into the number of shares of our common stock determined by dividing the $1,000 stated value per share of the Series C Preferred Stock by a conversion price of $148.14 per share. In addition, the conversion price per share is subject to adjustment for stock dividends, distributions, subdivisions, combinations or reclassifications. Subject to limited exceptions, a holder of the Series C Preferred Stock will not have the right to convert any portion of the Series C Preferred Stock to the extent that, after giving effect to the conversion, the holder, together with its affiliates, would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to its conversion. A holder of the Series C Preferred Stock, upon notice to us, may increase or decrease the beneficial ownership limitation provisions of such holder’s Series C Preferred Stock, provided that in no event shall the limitation exceed 9.99% of the number of shares of our common stock outstanding immediately after giving effect to its conversion. In the event that a conversion is effected at our option, we will exercise such option to convert shares of Series C Preferred Stock on a pro rata basis among all of the holders based on such holders’ shares of Series C Preferred Stock.

Fundamental Transactions. In the event we effect certain mergers, consolidations, sales of substantially all of our assets, tender or exchange offers, reclassifications or share exchanges in which our common stock is effectively converted into or exchanged for other securities, cash or property, we consummate a business combination in which another person acquires 50% of the outstanding shares of our common stock, or any person or group becomes the beneficial owner of 50% of the aggregate ordinary voting power represented by our issued and outstanding common stock, then, upon any subsequent conversion of the Series C Preferred Stock, the holders of the Series C Preferred Stock will have the right to receive any shares of the acquiring corporation or other consideration it would have been entitled to receive if it had been a holder of the number of shares of common stock then issuable upon conversion in full of the Series C Preferred Stock.

Dividends. Holders of Series C Preferred Stock shall be entitled to receive dividends (on an as-if-converted-to-common-stock basis) in the same form as dividends actually paid on shares of the common stock when, as and if such dividends are paid on shares of common stock.

Voting Rights. Except as otherwise provided in the certificate of designation or as otherwise required by law, the Preferred Stock has no voting rights.

Liquidation Preference. Upon our liquidation, dissolution or winding-up, whether voluntary or involuntary, holders of Series C Preferred Stock will be entitled to receive out of our assets, whether capital or surplus, the same amount that a holder of common stock would receive if the Series C Preferred Stock were fully converted (disregarding for such purpose any conversion limitations under the certificate of designation) to common stock, which amounts shall be paid pari passu with all holders of common stock.

Redemption Rights. We are not obligated to redeem or repurchase any shares of Series C Preferred Stock. Shares of Series C Preferred Stock are not otherwise entitled to any redemption rights, or mandatory sinking fund or analogous provisions.

Series D Preferred Stock

Our board of directors designated 4,656 shares of our preferred stock as Series D Preferred Stock. As of September 29, 2023, there were 180 shares of Series D Preferred stock outstanding which are convertible into 11,919 shares of our common stock.

Conversion. Each share of Series D Preferred Stock is convertible at the option of the holder at any time, into the number of shares of our common stock determined by dividing the $1,000 stated value per share of the Preferred Stock by a conversion price of $15.102 per share. In addition, the conversion price per share is subject to adjustment for stock dividends, distributions, subdivisions, combinations or reclassifications. Subject to limited exceptions, a holder of the Preferred Stock will not have the right to convert any portion of the Series D Preferred Stock to the extent that, after giving effect to the conversion, the holder, together with its affiliates, would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to its conversion. A holder of the Series D Preferred Stock, upon notice to us, may increase or decrease the beneficial ownership limitation provisions of such holder’s Series D Preferred Stock, provided that in no event shall the limitation exceed 9.99% of the number of shares of our common stock outstanding immediately after giving effect to its conversion.

Fundamental Transactions. In the event we effect certain mergers, consolidations, sales of substantially all of our assets, tender or exchange offers, reclassifications or share exchanges in which our common stock is effectively converted into or exchanged for other securities, cash or property, we consummate a business combination in which another person acquires 50% of the outstanding shares of our common stock, or any person or group becomes the beneficial owner of 50% of the aggregate ordinary voting power represented by our issued and outstanding common stock, then, upon any subsequent conversion of the Series D Preferred Stock, the holders of the Series D Preferred Stock will have the right to receive any shares of the acquiring corporation or other consideration it would have been entitled to receive if it had been a holder of the number of shares of common stock then issuable upon conversion in full of the Series D Preferred Stock.

Dividends. Holders of Preferred Stock shall be entitled to receive dividends (on an as-if-converted-to-common-stock basis) in the same form as dividends actually paid on shares of the common stock when, as and if such dividends are paid on shares of common stock.

Voting Rights. Except as otherwise provided in the certificate of designation or as otherwise required by law, the Series D Preferred Stock has no voting rights.

Liquidation Preference. Upon our liquidation, dissolution or winding-up, whether voluntary or involuntary, holders of Series D Preferred Stock will be entitled to receive out of our assets, whether capital or surplus, the same amount that a holder of common stock would receive if the Series D Preferred Stock were fully converted (disregarding for such purpose any conversion limitations under the certificate of designation) to common stock, which amounts shall be paid pari passu with all holders of common stock.

Redemption Rights. We are not obligated to redeem or repurchase any shares of Series D Preferred Stock. Shares of Series D Preferred Stock are not otherwise entitled to any redemption rights, or mandatory sinking fund or analogous provisions.

Future Preferred Stock.

Our boardBoard of directorsDirectors will fix the rights, preferences, privileges, qualifications and restrictions of the preferred stock of each series that we sell under this prospectus and applicable prospectus supplements in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or incorporate by reference into the registration statement of which this prospectus is a part the form of any certificate of designation that describes the terms of the series of preferred stock we are offering before the issuance of the related series of preferred stock. This description will include:

When we issue shares of preferred stock under this prospectus, the shares will be fully paid and nonassessable and will not have, or be subject to, any preemptive or similar rights.

The General Corporation Law of the State of Delaware, the state of our incorporation, provides that the holders of preferred stock will have the right to vote separately as a class on any proposal involving fundamental changes in the rights of holders of that preferred stock. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation.

Description of Other Outstanding Securities of the Company

Warrants

As of September 30, 2019,29, 2023, there were 391,3191,244,754 common stock purchase warrants outstanding, which expire between July 1, 2019February 2025 and May 2023.February 2028. Each of these warrants entitles the holder to purchase one share of common stock at prices ranging between $7,992$2.70 and $2.874, as converted, per share, with a weighted average exercise price of $34.49$150 per share. Certain of these warrants has a net exercise provision under which its holder may, in lieu of payment of the exercise price in cash, surrender the warrant and receive a net amount of shares based on the fair market value of our common stock at the time of exercise of the warrant after deduction of the aggregate exercise price. Additionally, certain of these warrants entitle a holder to also effect an “alternative cashless exercise” wherein the holder may surrender a certain number of warrants in return for a lesser number of shares of our common stock on a cashless basis. Each of these warrants also contains provisions for the adjustment of the exercise price and the aggregate number of shares issuable upon the exercise of the warrant in the event of dividends, share splits, reorganizations and reclassifications and consolidations. Certain of these warrants contain a provision requiring a reduction to the exercise price in the event we issue common stock, or securities convertible into or exercisable for common stock, at a price per share lower than the warrant exercise price.

The holders of certain of these warrants have registration rights, that are outlined below under the heading “Registration Rights.”as described in greater detail below.

May 2018 PublicFebruary 2023 Offering Warrants

On May 14, 2018,February 7, 2023, we issued 379,000a Class C Common Stock Purchase Warrant to purchase up to 2,150,000 shares of Common Stock (the “Class C Warrants”) and a Class D Common Stock Purchase Warrant to purchase up to 1,075,000 shares of Common Stock (the “Class D Warrants”). The Class C and Class D Warrants are exercisable at a price of $5.60 per share. The Class C Warrants will expire five years from the date of issuance and the Class D Warrants will expire three years from the date of issuance. In addition, a holder may also effect an “alternative cashless exercise” wherein the aggregate number of shares of common stock warrants (the “May 2018 Warrants”)issuable in such alternative cashless exercise shall equal the product of (x) the aggregate number of shares of common stock that would be issuable upon exercise of the Class C Warrant or Class D Warrant in accordance with the terms of such warrant if such exercise were by means of a public offering. cash exercise rather than a cashless exercise and (y) 0.40 with respect to the Class C Warrant or 0.80 with respect to the Class D Warrant.

The materialfollowing summary of certain terms and provisions of the May 2018Class C Warrants, and Class D Warrants is not complete and is subject to, and qualified in its entirety by the provisions of the form of Class C Warrant, and the form of Class D Warrant, which are filed as exhibits to this registration statement.

Exercisability. The Class C Warrants are summarized below. This summaryexercisable at any time after their original issuance and at any time up to the date that is five years after their original issuance. The Class D Warrants are exercisable at any time after their original issuance and at any time up to the date that is three years after their original issuance. Each of the May 2018Class C Warrants, Class D Warrants, are exercisable, at the option of each holder, in whole or in part by delivering to us a duly executed exercise notice and, at any time a registration statement registering the issuance of the shares of common stock underlying the Class C Warrants or Class D Warrants, under the Securities Act of 1933, as amended (the “Securities Act”) is effective and available for the issuance of such shares, by payment in full in immediately available funds for the number of shares of common stock purchased upon such exercise. If a registration statement registering the issuance of the shares of common stock underlying the Class C Warrants, Class D Warrants, under the Securities Act is not effective or available, the holder may, in its sole discretion, elect to exercise the Class C Warrant or Class D Warrant, through a cashless exercise, in which case the holder would receive upon such exercise the net number of shares of common stock determined according to the formula set forth in the warrant. We may be required to pay certain amounts as liquidated damages as specified in the warrants in the event we do not deliver shares of common stock upon exercise of the warrants within the time periods specified in the warrants. In addition, a holder may also effect an “alternative cashless exercise.” In such event, the aggregate number of shares of common stock issuable in such alternative cashless exercise shall equal the product of (x) the aggregate number of shares of common stock that would be issuable upon exercise of the Class C Warrant or Class D Warrant in accordance with the terms of such warrant if such exercise were by means of a cash exercise rather than a cashless exercise and (y) 0.40 with respect to the Class C Warrant or 0.80 with respect to the Class D Warrant. No fractional shares of common stock will be issued in connection with the exercise of a Class C Warrant or Class D Warrant. With respect to any alternative cashless exercise, fractional shares will be rounded down to the nearest whole share.

Fractional Shares. No fractional shares of common stock will be issued in connection with the exercise of a warrant. Other than as described above with respect to alternative cashless exercises, in lieu of fractional shares, we will, at our election, either pay the holder an amount in cash equal to the fractional amount multiplied by the exercise price or round up to the next whole share.

Exercise Limitation. A holder will not have the right to exercise any portion of the Class C Warrants, or Class D Warrants if the holder (together with its affiliates) would beneficially own in excess of 4.99% (or, upon election by a holder prior to the issuance of any warrants, 9.99%) of the number of shares of our common stock outstanding immediately after giving effect to the exercise, as such percentage ownership is determined in accordance with the terms of the warrants. However, any holder may increase or decrease such percentage to any other percentage not in excess of 9.99%, upon at least 61 days’ prior notice from the holder to us with respect to any increase in such percentage.

Exercise Price. The exercise price per whole share of common stock purchasable upon exercise of the Class C Warrants and the Class D Warrants is $5.60 per share. The exercise price and number of shares of common stock issuable on exercise are subject to appropriate adjustments in the event of certain stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting our common stock.

Transferability. Subject to applicable laws, the Class C Warrants and Class D Warrants may be offered for sale, sold, transferred or assigned without our consent.

Exchange Listing. We do not intend to list the Class C Warrants or the Class D Warrants on any securities exchange or other trading market. Without an active trading market, the liquidity of these securities will be limited.

Warrant Agent. The Class C Warrants and Class D Warrants are issued in registered form under a warrant agreement between American Stock Transfer & Trust Company, LLC, as warrant agent, and us. The Class C Warrants and Class D Warrants shall initially be represented only by one or more global warrants deposited with the warrant agent, as custodian on behalf of The Depository Trust Company (DTC) and registered in the name of Cede & Co., a nominee of DTC, or as otherwise directed by DTC.

Fundamental Transactions. In the event of a fundamental transaction, and generally including, with certain exceptions, any reorganization, recapitalization or reclassification of our common stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding shares of common stock, or any person or group becoming the beneficial owner of 50% of the voting power represented by our outstanding shares of common stock, the holders of the Class C Warrants and Class D Warrants will be entitled to receive upon exercise of the warrants the kind and amount of securities, cash or other property that the holders would have received had they exercised the warrants immediately prior to such fundamental transaction. In addition, in the event of a fundamental transaction, we or the successor entity, at the request of a holder of Class C Warrants or Class D Warrants, will be obligated to purchase any unexercised portion of such Class C Warrants or Class D Warrants in accordance with the terms of the warrants. Additionally, as more fully described in the warrants, in the event of certain fundamental transactions, the holders of the warrants will be entitled to receive consideration in an amount equal to the Black Scholes value of the warrants on the date of consummation of such transaction.

Rights as a Shareholder. Except as otherwise provided in the Class C Warrants and Class D Warrants or by virtue of such holder’s ownership of our shares of common stock, the holder of a Class C Warrant or Class D Warrant does not have the rights or privileges of a holder of our common stock, including any voting rights, until the holder exercises the warrant.

Governing Law. The Class C Warrants, Class D Warrants, and warrant agreement are governed by New York law.

Maxim and Ascendiant February 2023 Warrants

In connection with the February 2023 Offering, we issued (i) to Maxim, as our sole placement agent for the 2023 Offering, 73,100 warrants to purchase shares of our common stock and (ii) to Ascendiant, as a financial advisor to us in the February 2023 Offering, 12,900 warrants to purchase shares of our common stock (collectively, the “Placement Agent Warrants”). The Placement Agent Warrants will expire on February 7, 2028. The Placement Agent Warrants are exercisable at a price of $6.16 per share, subject to adjustment for stock dividends, distributions, subdivisions, combinations, or reclassifications, and for certain dilutive issuances. Subject to limited exceptions, a holder of the Placement Agent Warrants will not have the right to exercise any portion of the Placement Agent Warrants to the extent that, after giving effect to the exercise, the holder, together with its affiliates, and any other person acting as a group together with the holder or any of its affiliates, would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to its exercise. The holder, upon notice to us, may increase or decrease the beneficial ownership limitation provisions of the Placement Agent Warrants, provided that in no event shall the limitation exceed 9.99% of the number of shares of our common stock outstanding immediately after giving effect to the exercise of the Placement Agent Warrants. The Placement Agent Warrants may be exercised as to all or a lesser number of shares of our common stock and contain certain demand registration rights and unlimited “piggyback” registration rights for a period of five years after February 7, 2023, at our expense. We relied on the exemption from registration available under Section 4(a)(2) of the Securities Act in connection with the issuance of the Dealer Manager Warrants to Maxim and Ascendiant.

The foregoing description of the Placement Agent Warrants is not complete. For the complete terms of the May 2018Placement Agent Warrants, you should refer to the form of May 2018Placement Agent Warrant filed as an exhibit to this registration statement.

October 2022 Rights Offering Warrants

On October 17, 2022, we issued 308,321 common stock warrants designated as our “Class A” warrants and 308,321 common stock warrants designated as our “Class B” warrants (collectively the “October 2022 Warrants”) in a rights offering to our stockholders (the “October 2022 Rights Offering”). Each of these warrants entitles the holder to purchase one share of common stock at an exercise price of $2.70 per share. The Class A Warrants and Class B Warrants have the same terms, except that the Class A Warrants expire five years from the date of issuance and the Class B Warrants expire three years from the date of issuance. The material terms and provisions of the October 2022 Warrants are summarized below. This summary of the October 2022 Warrants is not complete. For the complete terms of the October 2022 Warrants, you should refer to the form of October 2022 Warrant filed as an exhibit to the registration statement of which this prospectus forms a part.

Pursuant to a warrant agency agreement between us and American Stock Transfer & Trust Company, LLC, as warrant agent, the May 2018October 2022 Warrants were issued in book-entry form and are represented only by one or more global warrants deposited with the warrant agent, as custodian on behalf of The Depository Trust Company, or DTC, and registered in the name of Cede & Co., a nominee of DTC, or as otherwise directed by DTC.

Exercisability Exercise Price and Term.The May 2018 Warrants entitle the holder to purchase shares of our common stock at an exercise price equal to $2.3867 per share. The May 2018 Warrants were exercisable immediately and expire on the five-year anniversary of the issuance date. The holder of a May 2018 Warrant will not be deemed a holder of our underlying common stock until the May 2018 Warrant is exercised, except as set forth in the May 2018 Warrants.

The exercise price and the number of shares issuable upon exercise of the May 2018 Warrants is subject to appropriate adjustment, similar to that described with respect to the Series B Preferred Stock above, in the event of recapitalization events, stock dividends, stock splits, stock combinations, reclassifications, reorganizations or similar events affecting our common stock. Subject to certain exclusions contained in the May 2018 Warrant, the exercise price is also subject to adjustment in the event that we sell or grant any option to purchase, or sell or grant any right to reprice, or otherwise dispose of or issue (or announce any offer, sale, grant or any option to purchase or other disposition) any common stock or common stock equivalents (as defined in the May 2018 Warrants), at an effective price per share less than the exercise price then in effect (including in the event we issued Series B Preferred Stock at a conversion price lower than the initial conversion price of the Series B Preferred Stock). In addition, May 2018 Warrant holders may be eligible to elect an alternative price in the event we issue certain variable price securities. The May 2018 Warrant holders must pay the exercise price in cash upon exercise of the May 2018 Warrants, unless such May 2018 Warrant holders are utilizing the cashless exercise provision of the May 2018 Warrants, which is only available in certain circumstances such as if the underlying shares are not registered with the SEC pursuant to an effective registration statement.

Fundamental Transactions.In addition, in the event we consummate a merger or consolidation with or into another person or other reorganization event in which our common shares are converted or exchanged for securities, cash or other property, or we sell, lease, license, assign, transfer, convey or otherwise dispose of all or substantially all of our assets or we or another person acquires 50% or more of our outstanding shares of common stock, referred to as a fundamental transaction, then following such event, the holders of the May 2018 Warrants will be entitled to receive upon exercise of the May 2018 Warrants the same kind and amount of securities, cash or property which the holders would have received had they exercised the May 2018 Warrants immediately prior to such fundamental transaction. Any successor to us or surviving entity is required to assume the obligations under the warrants. Notwithstanding the foregoing, in the event of a fundamental transaction, the holders will have the option, which may be exercised within 30 days after the consummation of the fundamental transaction, to require the Company or the successor entity purchase the Warrant from the holder by paying to the holder an amount of cash equal to the Black Scholes value of the remaining unexercised portion of the warrant on the date of the consummation of the fundamental transaction. However, if the fundamental transaction is not within the Company’s control, including not approved by the Company’s Board of Directors, the holder will only be entitled to receive from the Company or any successor entity, as of the date of consummation of such fundamental transaction, the same type or form of consideration (and in the same proportion), at the Black Scholes value of the unexercised portion of the May 2018 Warrant, that is being offered and paid to the holders of common stock of the Company in connection with the fundamental transaction, whether that consideration be in the form of cash, stock or any combination thereof, or whether the holders of common stock are given the choice to receive from among alternative forms of consideration in connection with the fundamental transaction.

Upon the holder’s exercise of a May 2018 Warrant, we will issue the shares of common stock issuable upon exercise of the May 2018 Warrant within two trading days following our receipt of a notice of exercise, provided that payment of the exercise price has been made (unless exercised via the “cashless” exercise provision).

Prior to the exercise of any May 2018 Warrants to purchase common stock, holders of the May 2018 Warrants will not have any of the rights of holders of the common stock purchasable upon exercise, including the right to vote, except as set forth therein.

May 2018 Warrant holders may exercise the May 2018 Warrants only if the issuance of the shares of common stock upon exercise of the May 2018 Warrants is covered by an effective registration statement, or an exemption from registration is available under the Securities Act and the securities laws of the state in which the holder resides. The May 2018 Warrant holders must pay the exercise price in cash upon exercise of the May 2018 Warrants unless there is not an effective registration statement or, if required, there is not an effective state law registration or exemption covering the issuance of the shares underlying the May 2018 Warrants (in which case, the May 2018 Warrants may only be exercised via a “cashless” exercise provision).

Beneficial Ownership Limitation. The May 2018 Warrant provides that we may not effect any exercise of the May 2018 Warrants, with certain exceptions, to the extent that, after giving effect to an attempted exercise, the holder (together with such holder’s affiliates, and any persons acting as a group together with such holder or any of such holder’s affiliates) would beneficially own a number of shares of common stock in excess of 4.99% (or, at the election of the holder, 9.99%) of the shares of our common stock then outstanding after giving effect to such exercise, referred to as the May 2018 Warrant Beneficial Ownership Limitation; provided, however, that upon notice to the Company, the holder may increase or decrease the May 2018 Warrant Beneficial Ownership Limitation, provided that in no event may the May 2018 Warrant Beneficial Ownership Limitation exceed 9.99% and any increase in the May 2018 Warrant Beneficial Ownership Limitation will not be effective until 61 days following notice of such increase from the holder to us.

Cashless Exercise.If a May 2018 Warrant is exercised via the “cashless” exercise provision, the holder will receive the number of shares equal to the quotient obtained by dividing (i) the difference between the VWAP (as determined pursuant to the terms of the May 2018 Warrants) and the exercise price of the May 2018 Warrant multiplied by the number of shares issuable under the May 2018 Warrant if such exercise were by means of a cash exercise by (ii) the VWAP (as determined pursuant to the terms of the May 2018 Warrants).

Jurisdiction and Waiver of Trial by Jury. Other than with respect to suits, actions or proceedings arising under the federal securities laws, the May 2018 Warrant provides for investors to consent to exclusive jurisdiction to courts located in New York, New York and provides for a waiver of the right to a trial by jury. It also provides that disputes are governed by New York law.

Repricing of Series E Warrants and Issuance of New Warrants

On March 6, 2018, the Company entered into a Warrant Amendment Agreement (the “Amendment Agreement”) with the holders of previously issued Series E Common Stock Purchase Warrants (collectively, the “Series E Investors”).

In connection with that certain Series E Common Stock Purchase Warrant between the Company and Series E Investors dated July 8, 2016, (the “Series E Warrant Agreement”) the Company issued to the Series E Investors warrants to purchase up to 22,278 shares of common stock (the “Warrant Shares”) at an exercise price of $60.00 per share, (the “Series E Investor Warrants”). Under the terms of the Amendment Agreement, in consideration of the Series E Investors exercising 22,278 of the Series E Investor Warrants (the “Series E Warrant Exercise”), the exercise price per share of the Series E Investor Warrants was reduced to $63.75 per share. In addition, and as further consideration, the Company issued to the Series E Investors warrants to purchase up to the number of shares of common stock equal to 100% of the number of Series E Warrant Shares issued pursuant to the Series E Warrant Exercise at an exercise price per share equal to $60.00 per share, the closing bid price for our common stock on March 5, 2018 (the “New Warrants”). The Series E Investors may exercise the remaining 33,899 Series E Investor Warrants at their discretion. The Amendment Agreement incorporated portions of the Series E Warrant Agreement, which contained customary representations, warranties and covenants by each of the Company and the Series E Investors.

The New Warrants are exercisable for up to five years from the Effective Date. The exercise price and number of shares issuable upon exercise of the New Warrants are subject to adjustment for stock splits, combinations, recapitalization events and certain dilutive issuances. The New Warrants are required to be exercised for cash, provided that if during the term of the New Warrants there is not an effective registration statement under the Securities Act covering the resale of the shares issuable upon exercise of the New Warrants, then the New Warrants may be exercised on a cashless (net exercise) basis. The New Warrant is attached as an exhibit to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

Securities Issued to North Stadium Investments, LLC

On July 28, 2017, the Company closed on a $2.5 million term loan (the “North Stadium Loan”) with North Stadium Investments, LLC (“North Stadium”), a company owned and controlled by the Company’s Chief Executive Officer and Chairman of the Board, Dr. Sonny Bal. In connection with the North Stadium Loan, the Company issued to North Stadium a Secured Promissory Note in the amount of $2.5 million (the “North Stadium Note”). The North Stadium Note bears interest at the rate of 10% per annum, requires the Company to make monthly interest only payments for a period of 12 months, and principal and any unpaid accrued interest are due and payable 12 months from the effective date of the North Stadium Note, July 28, 2017. The North Stadium Note is secured by substantially all of the assets of the Company pursuant to a security agreement between the Company and North Stadium dated July 28, 2017, and is junior to other previously existing security interests in such assets. The North Stadium Note is attached as an exhibit to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

In connection with the North Stadium Loan and as additional consideration for the North Stadium Loan, the Company issued to North Stadium a warrant to acquire shares of common stock with a five-year term (the “North Stadium Warrant”). As a result of the Company’s reverse stock splits since the North Stadium Warrant was issued, the North Stadium Warrant is exercisable for 1,833 shares of common stock as of the date of this prospectus, at an exercise price of $151.20 per share. The North Stadium Warrant also has a net exercise provision under which the holder may, in lieu of payment of the exercise price in cash, surrender the North Stadium Warrant and receive a net number of shares of common stock based on the fair market value of our common stock at the time of exercise of the North Stadium Warrant after deduction of the aggregate exercise price. The North Stadium Warrant also contains provisions for the adjustment of the exercise price and the aggregate number of shares of common stock issuable upon the exercise of the North Stadium Warrant in the event of dividends, share splits, reorganizations, reclassifications and consolidations. The North Stadium Warrant is attached as an exhibit to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

January 2017 Public Offering Warrants

On January 19, 2017, the Company issued common stock and warrants in a public offering, with each warrant exercisable for one share of common stock. The warrants expire on the five-year anniversary of the closing date. The exercise price is subject to appropriate adjustment in the event of recapitalization events, stock dividends, stock splits, stock combinations, reclassifications, reorganizations or similar events affecting the Company’s common stock. As a result of the Company’s reverse stock splits since the warrants were issued, the warrants are exercisable for 12,125 shares of common stock as of the date of this prospectus, at an exercise price of $198 per share. The warrants are callable by the Company in certain circumstances.

Subject to limited exceptions, a holder of these warrants will not have the right to exercise any portion of its warrants if the holder (together with such holder’s affiliates, and any persons acting as a group together with such holder or any of such holder’s affiliates) would beneficially own a number of shares of our common stock in excess of 4.99% (or, at the election of the holder, 9.99%) of the shares of our common stock then outstanding after giving effect to such exercise (the “2017 Warrant Beneficial Ownership Limitation”); provided, however, that upon notice to the Company, the holder may increase or decrease the 2017 Warrant Beneficial Ownership Limitation, provided that in no event shall the 2017 Warrant Beneficial Ownership Limitation exceed 9.99% and any increase in the Beneficial Ownership Limitation will not be effective until 61 days following notice of such increase from the holder to us.

The holders of these warrants must pay the exercise price in cash upon exercise of the warrants, unless such holders are utilizing the cashless exercise provision of the warrants, which is only available in certain circumstances such as if the underlying shares are not registered with the SEC pursuant to an effective registration statement. We intend to use commercially reasonable efforts to have the registration statement of which this prospectus forms a part, effective when the warrants are exercised.

In addition, in the event the Company consummates a merger or consolidation with or into another person or other reorganization event in which our common stock is converted or exchanged for securities, cash or other property, or the Company sells, leases, licenses, assigns, transfers, conveys or otherwise disposes of all or substantially all of our assets or the Company or another person acquires 50% or more of the outstanding shares of our common stock, then following such event, the holders of the warrants will be entitled to receive upon exercise of the warrants the same kind and amount of securities, cash or property which the holders would have received had they exercised the warrants immediately prior to such fundamental transaction. Any successor to us or surviving entity shall assume the obligations under the warrants.

In the event of a fundamental transaction other than one in which a successor entity that is a publicly traded corporation whose stock is quoted or listed on a trading market assumes the warrant such that the warrant shall be exercisable for the publicly traded common stock of such successor entity, then the Company or any successor entity will pay at the holder’s option, exercisable at any time concurrently with or within 30 days after the consummation of the fundamental transaction, an amount of cash equal to the value of the remaining unexercised portion of the warrants on the date of consummation of the fundamental transaction as determined in accordance with the Black Scholes option pricing model.

Upon the holder’s exercise of a warrant, the Company will issue the shares of common stock issuable upon exercise of the warrant within three trading days following the Company’s receipt of a notice of exercise, provided that payment of the exercise price has been made (unless exercised via the “cashless” exercise provision).

Prior to the exercise of a warrant, holders of the warrants will not have any of the rights of holders of our common stock purchasable upon exercise, including the right to vote, except as set forth therein.

The form of this warrant is attached as an exhibit to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

July 2016 Public Offering and Underwriter Warrants

In July 2016, the Company soldEach Class A and Class B Units that consisted of common stock and Series E Warrants. The Series E Warrants are exercisable for up to five years after the date of issuance. As of the date of this prospectus, there were 4,861 Series E Warrants outstanding, exercisable for 4,861 shares of our common stock, at an exercise price of $360 per share. The Series E warrants are callable by us in certain circumstances.

Subject to limited exceptions, a holder of Series E Warrants does not have the right to exercise any portion of its Series E Warrants if the holder (together with such holder’s affiliates, and any persons acting as a group together with such holder or any of such holder’s affiliates) would beneficially own a number of shares of common stock in excess of 4.99% (or, at the election of the holder, 9.99%) of the shares of our common stock then outstanding after giving effect to such exercise (the “Series E Beneficial Ownership Limitation”); provided, however, that upon notice to the Company, the holder may increase or decrease the Series E Beneficial Ownership Limitation, provided that in no event shall the Series E Beneficial Ownership Limitation exceed 9.99% and any increase in the Series E Beneficial Ownership Limitation will not be effective until 61 days following notice of such increase from the holder to us.

The exercise price and the number of shares issuable upon exercise of the Series E Warrants is subject to appropriate adjustment in the event of recapitalization events, stock dividends, stock splits, stock combinations, reclassifications, reorganizations or similar events affecting our common stock. The Series E Warrant holders must pay the exercise price in cash upon exercise of the Series E Warrants, unless such Series E Warrant holders are utilizing the cashless exercise provision of the Series E Warrants, which is only available in certain circumstances such as if the underlying shares are not registered with the SEC pursuant to an effective registration statement. We intend to use commercially reasonable efforts to have the registration statement of which this prospectus forms a part, effective when the Series E Warrants are exercised.

In addition, in the event we consummate a merger or consolidation with or into another person or other reorganization event in which our common shares are converted or exchanged for securities, cash or other property, or we sell, lease, license, assign, transfer, convey or otherwise dispose of all or substantially all of our assets or we or another person acquire 50% or more of our outstanding shares of common stock, then following such event, the holders of the Series E Warrants will be entitled to receive upon exercise of the warrants the same kind and amount of securities, cash or property which the holders would have received had they exercised the warrants immediately prior to such fundamental transaction. Any successor to us or surviving entity shall assume the obligations under the Series E Warrants.

In the event of a fundamental transaction approved by our board of directors and other than one in which a successor entity that is a publicly traded corporation whose stock is quoted or listed on a trading market assumes the Series E Warrant such that the Series E Warrant shall be exercisable for the publicly traded common stock of such successor entity, then the Company or any successor entity will pay at the holder’s option, exercisable at any time concurrently with or within 30 days after the consummation of the fundamental transaction, an amount of cash equal to the value of the remaining unexercised portion of the Series E Warrants on the date of consummation of the fundamental transaction as determined in accordance with the Black Scholes option pricing model.

Upon the holder’s exercise of a Series E Warrant, we will issue the shares of common stock issuable upon exercise of the Series E Warrant within three trading days following our receipt of a notice of exercise, provided that payment of the exercise price has been made (unless exercised via the “cashless” exercise provision).

Prior to the exercise of any Series E Warrants to purchase common stock, holders of the Series E Warrants will not have any of the rights of holders of the common stock purchasable upon exercise, including the right to vote, except as set forth therein.

The form of Series E Warrant and form of underwriters warrant are attached as exhibits to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

2016 Debt Exchange Warrants

On April 4, 2016, the Company entered into an exchange agreement (the “Riverside Exchange Agreement”) with Riverside Merchant Partners, LLC (“Riverside”), pursuant to which the Company agreed to exchange $1,000,000 of the principal amount outstanding under the term loan held by Riverside for a subordinated convertible promissory note in the principal amount of $1,000,000 and a warrant (the “First Riverside Warrant”) (the “Riverside Exchange”). In addition, pursuant to the terms and conditions of the Riverside Exchange Agreement, the Company and Riverside exchanged an additional $2,000,000 of the principal amount of the term loan for an additional subordinated convertible promissory note in the principal amount of up to $2,000,000 and an additional warrant (the “Second Riverside Warrant” and, together with the First Exchange Warrant, the “Riverside Warrants”). As a result of the Company’s reverse stock splits since the Riverside Warrants were issued, the First Riverside Warrant is exercisable for 278 shares of common stock as of the date of this prospectus, at an exercise price of $583.20 per share, and the Second Riverside Warrant is exercisable for 278 shares of common stock as of the date of this prospectus, at an exercise price of $597.60 per share.

The Riverside Warrants are exercisable until the five-year anniversary of six months after the date of issuance of the Riverside Warrants. The Riverside Warrants have a net exercise provision under which the holder may, in lieu of payment of the exercise price in cash, surrender the warrant and receive a net number of shares of common stock based on the fair market value of our common stock at the time of exercise of the Riverside Warrants after deduction of the aggregate exercise price. The Riverside Warrants also contain provisions for the adjustment of the exercise price and the aggregate number of shares of common stock issuable upon the exercise of the Riverside Warrants in the event of dividends, share splits, reorganizations, reclassifications and consolidations.

In the event of a fundamental transaction approved by our board of directors, including but not limited to a transaction in which the Company, directly or indirectly, in one or more related transactions consummates a stock or share purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with another person or group of persons whereby such other person or group acquires more than 50% of the outstanding shares of our common stock (not including any shares of common stock held by the other person or other persons making or party to, or associated or affiliated with the other persons making or party to, such stock or share purchase agreement or other business combination), other than one in which a successor entity that is a publicly traded corporation whose stock is quoted or listed on a trading market assumes the warrant such that the warrant shall be exercisable for the publicly traded common stock of such successor entity, then the Company or any successor entity will pay at the holder’s option, exercisable at any time concurrently with or within 30 days after the consummation of the fundamental transaction, an amount of cash equal to the value of the remaining unexercised portion of the warrants on the date of consummation of the fundamental transaction as determined in accordance with the Black Scholes option pricing model.

The form of Riverside Warrant is attached as an exhibit to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

Westlake Securities Warrants – 2016

As compensation paid in connection with the consummation of a private placement in 2016, the Company issued a warrant to Westlake Securities LLC on January 28, 2016 (the “2016 Westlake Warrant”). The 2016 Westlake Warrant is exercisable for five years after the date of issuance. As a result of the Company’s reverse stock splits the 2016 Westlake Warrant is exercisable for 208 shares of common stock as of the date of this prospectus at an exercise price of $702.00 per share. The 2016 Westlake Warrant has a net exercise provision under which the holder may, in lieu of payment of the exercise price in cash, surrender the warrant and receive a net number of shares of common stock based on the fair market value of our common stock at the time of exercise of the warrant after deduction of the aggregate exercise price. The 2016 Westlake Warrant contains provisions for the adjustment of the exercise price and the aggregate number of shares of common stock issuable upon the exercise of the warrant in the event of dividends, share splits, reorganizations, reclassifications and consolidations. The 2016 Westlake Warrant is attached as an exhibit to the registration statement of which this prospectus is a part and are incorporated herein by reference.

2015 Series A Warrants

On September 11, 2015, the Company closed a concurrent public and private offering (the “2015 Offerings”) of common stock and Series A, Series B and Series C Warrants. The Series B and Series C Warrants have since been either fully exercised or expired in accordance with their terms, and only 278 Series A Warrants remain outstanding as of the date of this prospectus. On December 11, 2015, the Company entered into an Amended and Restated Series A Warrant (the “Series A Warrant Amendment”) with each of the holders of the Series A Warrants (each an “Investor”). The Series A Warrants are exercisable on a cashless basis, subject to certain conditions. As a result of the Company’s reverse stock splits since this warrant was issued, the outstanding Series A Warrants are exercisable for 278 shares of common stock as of the date of this prospectus, at an exercise price of $540.00 per share. The Series A Warrant also contains provisions for the adjustment of the exercise price and the aggregate number of shares of common stock issuable upon the exercise of the warrant in the event of dividends, share splits, reorganizations, reclassifications and consolidations. The Series A Warrant prohibits the Company from entering into variable rate transactions without the holder’s consent.

In the event of a fundamental transaction approved by our board of directors, including but not limited to a transaction in which the Company, directly or indirectly, in one or more related transactions consummates a stock or share purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with another person or group of persons whereby such other person or group acquires more than 50% of the outstanding shares of our common stock (not including any shares of common stock held by the other person or other persons making or party to, or associated or affiliated with the other persons making or party to, such stock or share purchase agreement or other business combination), other than one in which a successor entity that is a publicly traded corporation whose stock is quoted or listed on a trading market assumes the warrant such that the warrant shall be exercisable for the publicly traded common stock of such successor entity, then the Company or any successor entity will pay at the holder’s option, exercisable at any time concurrently with or within 30 days after the consummation of the fundamental transaction, an amount of cash equal to the value of the remaining unexercised portion of the warrants on the date of consummation of the fundamental transaction as determined in accordance with the Black Scholes option pricing model.

As compensation paid in connection with the consummation of the 2015 Offerings, the Company issued a warrant to Ladenburg Thalmann & Co. Inc. on September 11, 2015 (the “Ladenburg Warrant”), who acted as placement agent for the 2015 Offerings. As a result of the Company’s reverse stock splits since the Ladenburg Warrant was issued, the Ladenburg Warrant is exercisable for 122 shares of common stock as of the date of this prospectus, at an exercise price of $2,538.00 per share. The Ladenburg Warrant is exercisable from March 12, 2016 until September 8, 2020. The Ladenburg Warrant has a net exercise provision under which the holder may, in lieu of payment of the exercise price in cash, surrender the warrant and receive a net number of shares of common stock based on the fair market value of our common stock at the time of exercise of the Ladenburg Warrant after deduction of the aggregate exercise price. The Ladenburg Warrant also contains provisions for the adjustment of the exercise price and the aggregate number of shares of common stock issuable upon exercise of the Ladenburg Warrant in the event of dividends, share splits, reorganizations, reclassifications and consolidations.

In the event of a fundamental transaction approved by our board of directors, including but not limited to a transaction in which the Company, directly or indirectly, in one or more related transactions consummates a stock or share purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with another person or group of persons whereby such other person or group acquires more than 50% of the outstanding shares of our common stock (not including any shares of common stock held by the other person or other persons making or party to, or associated or affiliated with the other persons making or party to, such stock or share purchase agreement or other business combination), other than one in which a successor entity that is a publicly traded corporation whose stock is quoted or listed on a trading market assumes the warrant such that the warrant shall be exercisable for the publicly traded common stock of such successor entity, then the Company or any successor entity will pay at the holder’s option, exercisable at any time concurrently with or within 30 days after the consummation of the fundamental transaction, an amount of cash equal to the value of the remaining unexercised portion of the warrants on the date of consummation of the fundamental transaction as determined in accordance with the Black Scholes option pricing model.

The Series A Warrant and the Ladenburg Warrant are attached as exhibits to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

2014 Unit Purchase Option and Related Warrants

In connection with a public offering of units, with each unit consisting of one share of common stock and one warrant to purchase multiple shares of common stock in December 2014 we issued to Dawson James Securities, Inc. a Unit Purchase Option (the “Unit Purchase Option”) to purchase units. The Unit Purchase Option is exercisable until five years from the date of issuance. As a result of the Company’s reverse stock splits since these units were issued, this Unit Purchase Option is exercisable for 106 units as of the date of this prospectus, at an exercise price of $7,696.80 per unit. The Unit Purchase Option also has a net exercise provision under which the holder may, in lieu of payment of the exercise price in cash, surrender the Unit Purchase Option and receive a net number of units based on the fair market value of the units at the time of exercise of the Unit Purchase Option after deduction of the aggregate exercise price. The Unit Purchase Option also contains provisions for the adjustment of the exercise price and the aggregate number of units issuable upon the exercise of the Unit Purchase Option in the event of dividends, share splits, reorganizations, reclassifications and consolidations. The form of the Unit Purchase Option is attached as an exhibit to the registration statement of which this prospectus forms a part and is incorporated herein by reference.

The warrants issuable upon exercise of the Unit Purchase Option terminate on the fifth anniversary of the date of issuance. As a result of the Company’s reverse stock splits, these warrants now have an exercise price of $7,696.80per share. The number of shares of common stock issuable upon exercise is subject to appropriate adjustment in the event of stock dividends, stock splits, reorganizations or similar events affecting our common stock and the exercise price. This warrant contains a provision requiring a reduction to the exercise price in the event we issue common stock, or securities convertible into or exercisable for common stock, at a price per share lower than the warrant exercise price.

Cashless Exercise Provision. Holders may exercise warrants by paying the exercise price in cash or, in lieu of payment of the exercise price in cash, at any time 120 days after issuance, by electing to receive a cash payment from us equal to the Black Scholes Value (as defined below) of the number of shares the holder elects to exercise (the “Black Scholes Payment”); provided that we have discretion as to whether to deliver the Black Scholes Payment or, subject to meeting certain conditions, to deliver a number of shares of our common stock determined according to the following formula:

Total Shares = (A x B) / C

Where:

As defined in the warrants, “Black Scholes Value” means the Black Scholes value of an option for one share of our common stock at the date of the applicable Black Scholes Payment or cashless exercise, as such Black Scholes value is determined, calculated using the Black Scholes Option Pricing Model obtained from the “OV” function on Bloomberg utilizing (i) an underlying price per share equal to the closing bid price of the common stock as of trading day immediately preceding the date of issuance of the warrant, (ii) a risk-free interest rate corresponding to the U.S. Treasury rate for a period equal to the remaining term of the warrant as of the applicable Black Scholes Payment or cashless exercise, (iii) a strike price equal to the exercise price in effect at the time of the applicable Black Scholes Payment or cashless exercise, (iv) an expected volatility equal to 135% and (v) a remaining term of such option equal to five (5) years (regardless of the actual remaining term of the warrant).

If, at any time a warrant is outstanding, the Company consummates any fundamental transaction, as described in the warrants and generally including any consolidation or merger into another corporation, or the sale of all or substantially all of our assets, or other transaction in which our common stock is converted into or exchanged for other securities or other consideration, the holder of any warrants will thereafter receive, the securities or other consideration to which a holder of the number of shares of common stock then deliverable upon the exercise or exchange of such warrants would have been entitled upon such consolidation or merger or other transaction. Notwithstanding the foregoing, in connection with a fundamental transaction, at the request of a holder of warrants we will be required to purchase the warrant from the holder by paying to the holder cash in an amount equal to the Black Scholes value of the warrant, as described in such warrant. The form of this warrant is attached as an exhibit to the registration statement of which this prospectus is a part and is incorporated herein by reference.

Kipke Warrant

As compensation paid in connection with the consummation of a bridge financing in 2014, the Company issued a warrant to purchase shares of common stock to Karl Kipke, who acted as a financial advisor in the bridge financing. As a result of the Company’s reverse stock splits this warrant is exercisable for 5 shares of common stock as of the date of this prospectus, at an exercise price of $6,156.00 per share. The warrant has a net exercise provision under which the holder may, in lieu of payment of the exercise price in cash, surrender the warrant and receive a net number of shares of common stock based on the fair market value of our common stock at the time of exercise of the warrant after deduction of the aggregate exercise price. The form of this warrant is attached as an exhibit to the registration statement of which this prospectus is a part and is incorporated herein by reference.

Outstanding December 2012 Warrants

On December 17, 2012, in connection with entering into a commercial lending transaction, we issued warrants to purchase a total of 270,000 shares of our Series F convertible preferred stock to two of our institutional lenders. These warrants are exercisable for ten years after the date of issuance. As a result of the Company’s reverse stock splits since these warrants were issued and other corporate changes, these warrants are exercisable for 13 shares of common stock as of the date of this prospectus, at an exercise price of $9,279.00 per share. These warrants have a net exercise provision under which the holder may, in lieu of payment of the exercise price in cash, surrender the warrant and receive a net number of shares of common stock based on the fair market value of our common stock at the time of exercise of the warrant after deduction of the aggregate exercise price. Each of these warrants also contains provisions for the adjustment of the exercise price and the aggregate number of shares of common stock issuable upon the exercise of the warrant in the event of dividends, share splits, reorganizations, reclassifications and consolidations. These warrants are attached as exhibits to the registration statement of which this prospectus is a part and are incorporated herein by reference.

Registration Rights

We have entered into various agreements with holders of shares of our common stock and warrants to acquire shares of our common stock that under certain circumstances require us to register with the SEC such shares of common stock and the shares of common stock issuable upon exercise of the warrants. These registration rights are generally subject to certain conditions and limitations, including our right to limit the number of shares included in any such registration under certain circumstances. We are generally required to pay all expenses incurred in connection with registrations effected in connection with the registration rights, excluding selling expenses such as broker commissions and underwriting discounts. The registration rights may be transferred to any transferee or assignee of the holder of such registrations rights who agrees to be bound by the terms of the registration rights agreement.

Furthermore, the terms of the agreements generally provide that we will not be required to maintain the effectiveness of any registration statement, or file another registration statement, with respect to any registrable securities that are not subject to the current public information requirement under Rule 144 and that are eligible for resale without volume or manner-of-sale restrictions.

Piggyback Rights. Pursuant to the terms of the Unit Purchase Option, if at any time while the Unit Purchase Option is outstanding, we file a registration statement under the Securities Act to register the sale of any of our securities, we will be required to include in such registration statement the shares of common stock underlying the Unit Purchase Option. We intend to seek a waiver of these registration rights in connection with this registration statement.

Generally, the foregoing piggyback registration rights do not apply to registrations of our securities that we initiate that are (i) issuable in connection with our acquisition of another entity or business or (ii) incidental to any of our equity compensation, employee stock purchase or other employee benefit plans or any sales agent/distributor equity incentive program that we may implement.

Series C Preferred Stock Included in Units Issuable in the Rights Offering

We will authorize the Series C Preferred Stock by filing a certificate of designation with the Secretary of State of Delaware. The certificate of designation may be authorized by our Board without approval by our stockholders.

Conversion.Each share of Preferred Stock will be convertible at our option at any time on or after the first anniversary of the expiration of the Rights Offering or at the option of the holder at any time, into the number of shares of our common stock determined by dividing the $1,000 stated value per share of the Preferred Stock by a conversion price of $ per share. In addition, the conversion price per share is subject to adjustment for stock dividends, distributions, subdivisions, combinations or reclassifications. Subject to limited exceptions, a holder of the Preferred Stock will not have the right to convert any portion of the Preferred Stock to the extent that, after giving effect to the conversion, the holder, together with its affiliates, would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to its conversion. A holder of the Preferred Stock, upon notice to the Company, may increase or decrease the beneficial ownership limitation provisions of such holder’s Preferred Stock, provided that in no event shall the limitation exceed 9.99% of the number of shares of our common stock outstanding immediately after giving effect to its conversion. In the event that a conversion is effected at our option, we will exercise such option to convert shares of Preferred Stock on a pro rata basis among all of the holders based on such holders’ shares of Preferred Stock.

Fundamental Transactions.In the event we effect certain mergers, consolidations, sales of substantially all of our assets, tender or exchange offers, reclassifications or share exchanges in which our common stock is effectively converted into or exchanged for other securities, cash or property, we consummate a business combination in which another person acquires 50% of the outstanding shares of our common stock, or any person or group becomes the beneficial owner of 50% of the aggregate ordinary voting power represented by our issued and outstanding common stock, then, upon any subsequent conversion of the Preferred Stock, the holders of the Preferred Stock will have the right to receive any shares of the acquiring corporation or other consideration it would have been entitled to receive if it had been a holder of the number of shares of common stock then issuable upon conversion in full of the Preferred Stock.

Dividends.Holders of Preferred Stock shall be entitled to receive dividends (on an as-if-converted-to-common-stock basis) in the same form as dividends actually paid on shares of the common stock when, as and if such dividends are paid on shares of common stock.

Voting Rights.Except as otherwise provided in the certificate of designation or as otherwise required by law, the Preferred Stock has no voting rights.

Liquidation Preference.Upon our liquidation, dissolution or winding-up, whether voluntary or involuntary, holders of Preferred Stock will be entitled to receive out of our assets, whether capital or surplus, the same amount that a holder of common stock would receive if the Preferred Stock were fully converted (disregarding for such purpose any conversion limitations under the certificate of designation) to common stock, which amounts shall be paid pari passu with all holders of common stock.

Redemption Rights.We are not obligated to redeem or repurchase any shares of Preferred Stock. Shares of Preferred Stock are not otherwise entitled to any redemption rights, or mandatory sinking fund or analogous provisions.

Warrants Included in Units Issuable in the Rights Offering

The Warrants to be issued as a part of this Rights Offering will be designated as our “Series 1” warrants. These Warrants will be separately transferable following their issuance and through their expiration five years from the date of issuance. Each Warrant will entitle the holder to purchase one share of our common stock at an exercise price of $        per share from the date of issuance through its expiration. There is no public trading market for the Warrants and they will not be listed for trading on Nasdaq or any other securities exchange or market. The common stock underlying the Warrants, upon issuance, will also be traded on Nasdaq under the symbol “SINT.”

All Warrants that are purchased in the Rights Offering as part of the Units will be issued in book-entry, or uncertificated, form meaning that you will receive a DRS account statement from our transfer agent reflecting ownership of Warrants if you are a holder of record. The Subscription Agent will arrange for the issuance of the Warrants as soon as practicable after the closing, which will occur as soon as practicable after the Rights Offering has expired but which may occur up to five business days thereafter. At closing, all prorating calculations and reductions contemplated by the terms of the Rights Offering will have been effected and payment to us for the subscribed-for Units will have cleared. If you hold your shares of common stock in the name of a bank, broker, dealer, or other nominee, DTC will credit your account with your nominee with the Warrants you purchased in the Rights Offering.

Exercisability

Each Warrant will be exercisable at any time and will expire five years from the date of issuance. Each Class B Warrant is exercisable at any time and will expire three years from the date of issuance. The Warrants will beare exercisable, at the option of each holder, in whole or in part by delivering to us a duly executed exercise notice and payment in full for the number of shares of our common stock purchased upon such exercise, except in the case of a cashless exercise as discussed below. The number of shares of common stock issuable upon exercise of the Warrants is subject to adjustment in certain circumstances, including a stock split of, stock dividend on, or a subdivision, combination or recapitalization of the common stock. If we effect a merger, consolidation, sale of substantially all of our assets, or other similar transaction, then, upon any subsequent exercise of a Warrants, the Warrant holder will have the right to receive any shares of the acquiring corporation or other consideration it would have been entitled to receive if it had been a holder of the number of shares of common stock then issuable upon exercise in full of the Warrant.

Cashless Exercise

If at any time there is no effective registration statement registering, or the prospectus contained therein is not available for issuance of, the shares issuable upon exercise of the warrant, the holder may exercise the warrant on a cashless basis. When exercised on a cashless basis, a portion of the warrant is cancelled in payment of the purchase price payable in respect of the number of shares of our common stock purchasable upon such exercise.

Exercise Price

Each warrant represents the right to purchase one share of common stock at an exercise price equal to the Conversion Price. In addition, the exercise price per share is subject to adjustment for stock dividends, distributions, subdivisions, combinations, or reclassifications, and for certain dilutive issuances. The exercise price is also subject to adjustment in the event that we sell, issue, or grant any option to purchase, or sell or issue any right to reprice, or otherwise dispose of $or issue (or enter into any agreement relating to the offer, sale, grant or any option to purchase or other disposition) any common stock or convertible securities (as defined in the warrants), at an effective price per share less than the exercise price then in effect. In addition, if at any time there occurs a stock dividend, distribution, subdivision, combination, or reclassification and the volume weighted average price of the shares of common stock for the five trading days following such event is less than the exercise price then in effect (after giving effect to the adjustment of the exercise price pursuant to such event under the terms of the Warrants), then on the fifth trading day following such event, the exercise price shall be reduced to the volume weighted average price of the shares of common stock for the five trading days following such event.

Subject to limited exceptions, a holder of warrants will not have the right to exercise any portion of the warrant to the extent that, after giving effect to the exercise, the holder, together with its affiliates, and any other person acting as a group together with the holder or any of its affiliates, would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to its exercise. The holder, upon notice to us, may increase or decrease the beneficial ownership limitation provisions of the warrant, provided that in no event shall the limitation exceed 9.99% of the number of shares of our common stock outstanding immediately after giving effect to the exercise of the warrant.

Transferability

Subject to applicable laws and restrictions, a holder may transfer a warrant upon surrender of the warrant to us with a completed and signed assignment in the form attached to the warrant. The transferring holder will be responsible for any tax that liability that may arise as a result of the transfer.

No Market

There is no public trading market for the October 2022 Warrants and they will not be listed for trading on Nasdaq or any other securities exchange or market.

Rights as Stockholder

Except as set forth in the October 2022 Warrants, the holder of an October 2022 Warrant, solely in such holder’s capacity as a holder of such warrant, will not be entitled to vote, to receive dividends, or to any of the other rights of our stockholders.

Amendments and Waivers

The provisions of each October 2022 Warrant may be modified or amended or the provisions thereof waived with the written consent of us and the holder.

The October 2022 Warrants were issued pursuant to a warrant agent agreement by and between us and America Stock Transfer & Trust Company, the warrant agent.

Maxim and Ascendiant October 2022 Warrants

In connection with the October 2022 Rights Offering, we issued (i) to Maxim, as the dealer-manager in the October 2022 Rights Offering, 10,483 warrants to purchase shares of our common stock and (ii) to Ascendiant, as a financial advisor to us in the October 2022 Rights Offering, 1,850 warrants to purchase shares of the Company’s common stock (collectively, the “Dealer Manager Warrants”). The Dealer Manager Warrants are non-exercisable for 6 months from October 17, 2022 and will expire on September 23, 2027. The Dealer Manager Warrants will be exercisable at a price of $16.61 per share, subject to adjustment for stock dividends, distributions, subdivisions, combinations, or reclassifications, and for certain dilutive issuances. Subject to limited exceptions, a holder of the Dealer Manager Warrants will not have the right to exercise any portion of the Dealer Manager Warrants to the extent that, after giving effect to the exercise, the holder, together with its affiliates, and any other person acting as a group together with the holder or any of its affiliates, would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to its exercise. The holder, upon notice to us, may increase or decrease the beneficial ownership limitation provisions of the Dealer Manager Warrants, provided that in no event shall the limitation exceed 9.99% of the number of shares of our common stock outstanding immediately after giving effect to the exercise of the Dealer Manager Warrants. In addition, the Dealer Manager Warrants shall not be redeemable and may not be sold, transferred, assigned, pledged or hypothecated or be the subject of any hedging, short sale, derivative, put, or call transaction for a period of 180 days following September 23, 2022, except that they may be assigned, in whole or in part, to any officer or partner of Maxim (or to Ascendiant). The Dealer Manager Warrants may be exercised as to all or a lesser number of shares of our common stock, and contain unlimited “piggyback” registration rights for a period of five years after September 23, 2022, at the Company’s expense. We relied on the exemption from registration available under Section 4(a)(2) of the Securities Act in connection with the issuance of the Dealer Manager Warrants to Maxim and Ascendiant.

The foregoing description of the Dealer Manager Warrants is not complete. For the complete terms of the Dealer Manager Warrants, you should refer to the form of Dealer Manager Warrant filed as an exhibit to the registration statement of which this prospectus forms a part.

February 2020 Rights Offering Warrants

On February 6, 2020, we issued 63,720 common stock warrants (the “February 2020 Warrants”) in a rights offering to our stockholders. The material terms and provisions of the February 2020 Warrants are summarized below. This summary of the February 2020 Warrants is not complete. For the complete terms of the February 2020 Warrants, you should refer to the form of February 2020 Warrant filed as an exhibit to the registration statement of which this prospectus forms a part.

Pursuant to a warrant agency agreement between us and American Stock Transfer & Trust Company, LLC, as warrant agent, the February 2020 Warrants were issued in book-entry form and are represented only by one or more global warrants deposited with the warrant agent, as custodian on behalf of The Depository Trust Company, or DTC, and registered in the name of Cede & Co., a nominee of DTC, or as otherwise directed by DTC.

Exercisability. Each February 2020 Warrant became exercisable at the time of issuance and will expire five years from their issuance date. The February 2020 Warrants are exercisable, at the option of each holder, in whole or in part by delivering to us a duly executed exercise notice and payment in full for the number of shares of our common stock purchased upon such exercise, except in the case of a cashless exercise as discussed below. The number of shares of common stock issuable upon exercise of the February 2020 Warrants is subject to adjustment in certain circumstances, including a stock split of, stock dividend on, or a subdivision, combination or recapitalization of the common stock. If we effect a merger, consolidation, sale of substantially all of our assets, or other similar transaction, then, upon any subsequent exercise of a February 2020 Warrant, the February 2020 Warrant holder will have the right to receive any shares of the acquiring corporation or other consideration it would have been entitled to receive if it had been a holder of the number of shares of common stock then issuable upon exercise in full of the February 2020 Warrant.

Cashless Exercise. After the earlier of (a) the date that is 30 days after the initial exercise date of the February 2020 Warrants or (b) such trading day that the aggregate volume of shares of common stock sold since the expiration of the Offering exceeds three times the number of shares of common stock and common stock equivalents sold in the Offering, the holder shall be permitted to exercise the February 2020 Warrant, on a cashless basis, regardless of the then applicable trading price of the common stock on Nasdaq, for an aggregate number of shares of common stock equal to the product of (i) the aggregate number of shares of common stock that would be issuable upon exercise of the Warrant if such exercise were by means of a cash exercise and (ii) 0.70.

Additionally, if at any time there is no effective registration statement registering, or the prospectus contained therein is not available for issuance of, the shares issuable upon exercise of the warrant, the holder may exercise the warrant on a cashless basis, in which a portion of the warrant is cancelled in payment of the purchase price payable in respect of the number of shares of our common stock purchasable upon such exercise.

Exercise Price. Each February 2020 Warrant represents the right to purchase one share of common stock at an exercise price of $150 per share. In addition, the exercise price per share is subject to adjustment for stock dividends, distributions, subdivisions, combinations, or reclassifications, and for certain dilutive issuances. Subject to limited exceptions, a holder of warrants will not have the right to exercise any portion of the warrant to the extent that, after giving effect to the exercise, the holder, together with its affiliates, and any other person acting as a group together with the holder or any of its affiliates, would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to its exercise. The holder, upon notice to the Company, may increase or decrease the beneficial ownership limitation provisions of the warrant, provided that in no event shall the limitation exceed 9.99% of the number of shares of our common stock outstanding immediately after giving effect to the exercise of the warrant.

Fundamental Transactions. In the event we consummate a merger or consolidation with or into another person or other reorganization event in which our shares of common stock are converted or exchanged for securities, cash or other property, or we sell, lease, license, assign, transfer, convey or otherwise dispose of all or substantially all of our assets or we or another person acquires 50% or more of our outstanding shares of common stock, referred to as a fundamental transaction, then following such event, the holders will have the option, which may be exercised within 30 days after the consummation of the fundamental transaction, to require us or our successor entity purchase the February 2020 Warrant from the holder by paying to the holder an amount of cash equal to the Black Scholes value of the remaining unexercised portion of the warrant on the date of the consummation of the fundamental transaction. However, if the fundamental transaction is not within our control, including not approved by our Board of Directors, the holder will only be entitled to receive from us or any successor entity, as of the date of consummation of such fundamental transaction, the same type or form of consideration (and in the same proportion), at the Black Scholes value of the unexercised portion of the February 2020 Warrant, that is being offered and paid to the holders of our common stock in connection with the fundamental transaction, whether that consideration be in the form of cash, stock or any combination thereof, or whether the holders of common stock are given the choice to receive from among alternative forms of consideration in connection with the fundamental transaction.

Transferability. Subject to applicable laws and restrictions, a holder may transfer a warrant upon surrender of the warrant to us with a completed and signed assignment in the form attached to the warrant. The transferring holder will be responsible for any tax that liability that may arise as a result of the transfer.

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