Document:

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                                                                   Exhibit 10.49

                         REVENUE PARTICIPATION AGREEMENT

      This Revenue Participation Agreement (this "Agreement") is executed as of
the 20th day of November, 2003, by Drew Scientific, Inc. ("Company"), a Texas
corporation, for the benefit of Texas Mezzanine Fund Inc. ("Institution").

                                    RECITALS

      A. Company and Institution have entered into and executed that certain
Loan Agreement of even date herewith (the "Loan Agreement") pursuant to which
Institution has agreed to make a loan to Company in the stated principal amount
of $558,000.00(the "Loan"), upon the terms and conditions set forth in the Loan
Agreement.

      B. As part of the consideration for making the Loan, Company has agreed
that Institution may participate in certain revenues generated by Company's
business operations.

                                   AGREEMENTS

      NOW, THEREFORE, for and in consideration of the Loan and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Company and Institution hereby agree as follows:

      1. Participation Interest. Company hereby grants and assigns to
Institution one percent (1.0%) of Company's annual revenues in excess of
$11,500,000.00 (the "Participation Interest"), commencing with annual revenues
for Company's fiscal year commencing April 1, 2004.

      2. Payment of Participation Interest. During the term of this Agreement,
Company shall pay Institution the Participation Interest within one hundred
fifty (150) days after the end of each fiscal year (commencing with Borrower's
fiscal year ending March 31, 2005).

      3. Financial Information regarding Revenues. The term "annual revenues"
shall mean the revenues of the Company as reflected on the year-end audited
financial statements of the Company. Such financial statements shall be in
reasonable detail and prepared in accordance with generally accepted accounting
principles, consistently applied, and certified by the general partner of the
Company. Upon written request of Institution, Company shall provide to
Institution financial statements, balance sheets and such other information as
Institution deems necessary to periodically evaluate the financial condition of
Company. The Company represents, and Institution acknowledges, that Company's
achieving annual revenues in excess of $11,500,000.00 is highly uncertain and
speculative. Company specifically disclaims that it has represented to
Institution, or provided financial or other information to Institution that
reflects the Company will generate revenues in excess of $11,500,000.00 for the
year in which the Loan is made. Further, Company represents that it has not, and
does not, guarantee to Institution that Company shall ever achieve
$11,500,000.00 in annual revenues. Accordingly, Company and Institution
acknowledge and agree that there is a substantial risk that Institution may
never receive the Participation Interest in that Company's achieving annual
revenues in excess of $11,500,000.00 is highly uncertain and speculative.

      4. INTEREST. IT IS THE INTENT, UNDERSTANDING AND AGREEMENT OF COMPANY AND
INSTITUTION THAT THE PARTICIPATION INTEREST DOES NOT CONSTITUTE, NOR SHALL IT BE
CONSTRUED AS CONSTITUTING, INTEREST. TO THE GREATEST EXTENT PERMITTED BY LAW,
COMPANY HEREBY WAIVES ANY AND ALL PRESENT AND FUTURE RIGHTS TO ASSERT

REVENUE PARTICIPATION AGREEMENT - Page 1

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ANY CLAIM, ACTION OR CAUSE OF ACTION RELATING TO USURY, WHETHER AT LAW, BY
STATUTE OR IN EQUITY, UNDER STATE OR FEDERAL JURISDICTION, ARISING OUT OF,
CONNECTED WITH OR RELATING TO THE PARTICIPATION INTEREST. FURTHER, AND TO THE
GREATEST EXTENT PERMITTED BY LAW, COMPANY HEREBY FULLY AND COMPLETELY RELEASES
AND DISCHARGES INSTITUTION OF AND FROM ANY AND ALL CLAIMS, LIABILITIES, DEMANDS,
DAMAGES, DEBTS, ACTIONS AND CAUSES OF ACTION RELATING TO USURY, WHETHER AT LAW,
BY STATUTE OR IN EQUITY, UNDER STATE OR FEDERAL JURISDICTION, WHICH COMPANY HAS
OR MAY IN THE FUTURE CLAIM TO HAVE AGAINST INSTITUTION, ARISING OUT OF,
CONNECTED WITH OR RELATING TO THE PARTICIPATION INTEREST.

      5. Representations and Warranties of Company. Company hereby represents
and warrants to Institution as follows:

            a. Company has the full right, power and authority to execute and
      deliver this Agreement and to carry out the obligations set forth herein,
      and further that no parties not expressly made a party to this Agreement
      are required to join in this Agreement on behalf of Company in order to
      make this Agreement valid, binding and enforceable against Company;

            b. the execution and delivery of this Agreement, the consummation of
      the transactions contemplated herein, and the compliance by Company with
      this Agreement will not conflict with, violate or result in a breach of or
      constitute (with due notice or lapse of time, or both) a default under,
      any law, judicial decision, statute, ruling, rule, regulation, permit,
      certificate or ordinance in any way applicable to Company;

            c. no bankruptcy or insolvency proceedings are pending or
      contemplated by, or to the best knowledge of Company, against Company; and

            d. all information, reports, papers and data given to Institution by
      or on behalf of Company are accurate, complete and correct in all material
      respects and do not omit any fact the inclusion of which is necessary to
      prevent the facts contained therein from being materially misleading.

      6. Relationship of the Parties. No rights or benefits conferred upon
Institution by its acceptance of this Agreement shall constitute or be deemed to
constitute Institution a partner or joint venturer of or with Company.
Consequently, in no event shall Institution be liable for any of the debts,
liabilities or obligations of Company.

      7. Further Assurances. Company agrees to execute such further instruments
as may be, in the opinion of Institution, from time to time necessary or
appropriate to fully carry out the purposes hereof and/or to correct any error
that was caused by a unilateral mistake on the part of Institution, mutual
mistake on the part of Institution and Company, clerical mistake, calculation
error, computer malfunction, printing error or similar error. Company further
agrees that Institution shall not be liable for any damages incurred by Company
that are directly or indirectly caused by any such error.

      8. Indemnification. Company shall indemnify, protect, defend and hold
harmless Institution from and against any and all claims, demands, causes of
action, losses, damages, liabilities, suits, costs and expenses, including,
without limitation, attorneys' fees and court costs, asserted against or
suffered or incurred by Institution by reason of, arising out of or in
connection with (a) a breach or violation of any representation or warranty of
Company set forth in this Agreement, (b) a misrepresentation or an inaccurate

REVENUE PARTICIPATION AGREEMENT - Page 2

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statement of fact made by Company in this Agreement, or (c) a default by Company
in the performance of or failure of Company to perform any of its obligations or
agreements set forth in this Agreement.

      9. Controlling Agreement. All agreements between Company and Institution,
whether now existing or hereafter arising and whether written or oral, are
hereby limited so that in no contingency or event whatsoever, shall the interest
contracted for, charged, received, paid or agreed to be paid to Institution
exceed interest computed at the Maximum Rate (as defined below). If, from any
circumstance whatsoever, sums deemed to be interest would otherwise be payable
to Institution in excess of interest computed at the Maximum Rate, then such
sums payable to Institution shall be reduced to interest computed at the Maximum
Rate; and if from any circumstance Institution shall ever receive anything of
value deemed interest by applicable law in excess of interest computed at the
Maximum Rate, an amount equal to any excessive interest shall be applied to the
reduction of the principal balance of the Loan and not to the payment of
interest, or if such excessive interest exceeds the unpaid balance of principal
of the Loan, such excess shall be refunded to the Company or other appropriate
party. All interest paid or agreed to be paid to Institution shall, to the
extent permitted by applicable law, be amortized, prorated, allocated, and
spread throughout the full period until payment in full of the principal
(including the period of any renewal or extension) so that the interest for such
full period shall not exceed interest computed at the Maximum Rate. The term
"Maximum Rate" shall mean the highest lawful rate of interest applicable to the
Loan taking into account whichever of applicable federal law or Texas law
permits the higher rate of interest, and after also taking into consideration
all compensation deemed interest under applicable law.

      10. Severability. If any provision of this Agreement is or may be held by
a court of competent jurisdiction to be invalid, void, or unenforceable to any
extent, the validity of the remaining parts, terms or provisions of this
Agreement shall not be affected thereby, and such illegal or invalid part,
terms, or provision shall be deemed not to be part of this Agreement. The
remaining provisions shall nevertheless survive and continue in full force and
effect without being invalidated in any way to the extent the remaining
provisions further accomplish the goals and intents of this Agreement.

      11. Modification. No provision of this Agreement may be modified, waived
or terminated except by written instrument executed by the party against whom a
modification, waiver or termination is sought to be enforced.

      12. Termination. This Agreement shall terminate upon the maturity date of
the Loan, or the prepayment of the Loan, whichever is earlier, PROVIDED,
however, that in the event any payment(s) due and payable under this Agreement
remain unpaid as of the date of the maturity or earlier prepayment of the Loan,
then the obligation and liability of Company to pay such amounts shall continue
until the amounts due under this Agreement are fully paid and satisfied.

      13. Notices. Any notice, request or other communication required or
permitted to be given hereunder shall be in writing and shall be deemed to have
been given and received when deposited in a post office or official depository
of the United States Postal Service, postage prepaid, certified or registered
mail, return receipt requested, addressed to the respective parties as follows:

      If to the Company:         Drew Scientific, Inc.
                                 4230 Shilling Way
                                 Dallas, Texas 75237
                                 Attn: Keith Drew

REVENUE PARTICIPATION AGREEMENT - Page 3

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      If to Institution:         Texas Mezzanine Fund Inc.
                                 351 West Jefferson Blvd., Suite 800
                                 Dallas, Texas 75208
                                 Attn: Theresa Lee

Each of the parties hereto shall be entitled to specify a different address by
giving written notice to the other party hereto in accordance with this section.

      13. Governing Law and Venue. This Agreement shall be governed by and
construed accordance with the laws of the state of Texas and the laws of the
United States pertaining to transactions in Texas. Venue in any action arising
out of this Agreement shall lie in Dallas County, Texas.

      14. Entire Agreement. This Agreement embodies and constitutes the final
understanding and agreement between the parties hereto with respect to the
transaction contemplated in this Agreement, and may not be contradicted by
evidence of prior, contemporaneous or subsequent agreements, understandings,
representation and statements, oral or written. There are no unwritten oral
agreements between the parties hereto.

                                           COMPANY:

                                           DREW SCIENTIFIC, INC.,
                                           a Texas corporation

                                           By: /s/ Keith Drew
                                               -------------------------
                                           Name: Keith Drew
                                           Title: President

                                           INSTITUTION:

                                           TEXAS MEZZANINE FUND INC.,
                                           a Texas corporation

                                           By: /s/ Theresa Lee
                                               -------------------------
                                           Name: Theresa Lee
                                           Title: Vice-President

REVENUE PARTICIPATION AGREEMENT - Page 4<PAGE>
                                                                   Exhibit 10.50

                               SECURITY AGREEMENT

      This SECURITY AGREEMENT (this "Agreement") is executed and entered into by
and between TEXAS MEZZANINE FUND INC., a Texas corporation ("Secured Party"),
and DREW SCIENTIFIC, INC., a Texas corporation ("Debtor"), as follows:

                                   WITNESSETH:

      WHEREAS, Debtor and Secured Party have executed that certain Loan
Agreement of even date herewith (the "Loan Agreement") pursuant to the terms and
provisions of which Secured Party has agreed to loan Debtor the sum of Five
Hundred Fifty-Eight Thousand and No/100 Dollars ($558,000.00);

      WHEREAS, Debtor has executed a promissory note of even date herewith in
the stated principal amount of $558,000.00 (the "Note") payable to the order of
Secured Party pursuant to the terms and conditions contained therein; and

      WHEREAS, pursuant to the terms and provisions of the Note and the Loan
Agreement, the parties hereto wish to secure payment and performance of Debtor's
obligations under the Note and the Loan Agreement pursuant to the terms and
provisions set forth hereinbelow. (The Note, the Loan Agreement and any of the
other documents executed in connection with this loan may sometimes be
collectively referred to herein as the "Loan Documents".)

      NOW, THEREFORE, in consideration of Ten and No/100 Dollars ($10.00) and
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto hereby agree as follows:

      1. Security for Indebtedness. As security for full and timely payment,
performance and satisfaction of the Indebtedness (as defined below), Debtor
hereby grants to Secured Party a security interest in the Collateral (as defined
below).

      2. Collateral. The term "Collateral" shall mean all of the following
property Debtor now or later owns or has an interest in, wherever located:

            (a) All Accounts, Chattel Paper, contract rights, Documents,
      Instruments, Deposit Accounts and General Intangibles.

            (b) All Equipment and Fixtures.

            (c) All Inventory.

            (d) All Goods, Instruments, Documents, Investment Property, money or
      other property which are now or later in possession or control of Secured
      Party, or as to which Secured Party now or later controls possession.

            (e) All additions, accessions, attachments, replacements,
      substitutions, amendments, modifications, extensions, renewals,
      enlargements, products, Proceeds, income, interest, profits and
      distributions of or relating to the foregoing.

            (f) All books of account, customer lists and other Records relating
      in any way to the foregoing.

All terms capitalized above shall have the meanings assigned to them in the
Uniform Commercial Code of the State of Texas (the "Code").

      3. Indebtedness. As used herein, the term "Indebtedness" shall mean (a)
all of Debtor's debts, liabilities, covenants, agreements, promises and
obligations under the Note, the Loan Agreement, this Agreement and the other
Loan

SECURITY AGREEMENT - Page 1

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Documents, together with any and all renewals, extensions, increases,
rearrangements or modifications thereof, (b) all costs incurred by Secured Party
to obtain, preserve, perfect and enforce this Agreement and the security
interest in the Collateral, and maintain, preserve and collect the Collateral,
including without limitation taxes, assessments, insurance premiums, reasonable
attorneys' fees and legal expenses and expenses of sale, and (c) all future
loans and advances made by Secured Party to Debtor and all other debts,
obligations and liabilities of every kind and character of Debtor now or
hereafter existing in favor of Secured Party, it being contemplated that Debtor
may hereafter become indebted to Secured Party in further sum or sums.

      4. Insurance. Debtor will, at its own expense, maintain insurance with
respect to all Collateral in such amounts, against such risks, in such form and
with such insurers, as shall be reasonably satisfactory to Secured Party from
time to time. If requested by Secured Party, each policy for property damage
insurance shall provide for all losses to be paid directly to Secured Parry. If
requested by Secured Party, each policy of insurance maintained by Debtor shall
(a) name Debtor and Secured Party as insured parties thereunder (without any
representation or warranty by or obligation upon Secured Party) as their
interests may appear, (b) contain the agreement by the insurer that any loss
thereunder shall be payable to Secured Party notwithstanding any action,
inaction or breach of representation or warranty by Debtor, (c) provide that
there shall be no recourse against Secured Party for payment of premiums or
other amounts with respect thereto, and (d) provide that at least thirty (30)
days prior written notice of cancellation or of lapse shall be given to Secured
Party by the insurer. Debtor will, if requested by Secured Party, deliver to
Secured Party original or duplicate policies of such insurance and, as often as
Secured Party may reasonably request, a report of a reputable insurance broker
with respect to such insurance. Debtor will also, at the request of Secured
Party, duly execute and deliver instruments of assignment of such insurance
policies and cause the respective insurers to acknowledge notice of such
assignment. All insurance payments in respect of loss of or damage to any
Collateral shall be paid to Secured Party and applied as Secured Party in its
sole discretion deems appropriate.

      5. Books and Records of Debtor. Debtor will maintain accurate books and
records with respect to the Collateral. Said books and records will evidence the
security interest of Secured Party in the Collateral (but Debtor's failure to do
so shall never impair Secured Party's right hereunder) and will be kept at
Debtor's mailing address as specified in this Agreement.

      6. Distributions From Collateral. In the event Debtor shall become
entitled to receive or shall receive, in connection with any of the Collateral,
(a) any additions to or substitutions for any of the Collateral, or any rights
to such additions to or substitutions, (b) any distribution payable in property
or cash distributions, or (c) any distributions of any kind whatsoever, Debtor
shall accept same as encumbered by the security interest created hereby;
provided, however, in an Event of Default (as defined below), Debtor shall
deliver all distributions of any kind whatsoever declared and paid on account of
the Collateral to Secured Party.

      7. Representations and Warranties. Debtor warrants and represents to
Secured Party that (a) Debtor has power and authority to enter into this
Agreement, and to pledge the Collateral for the purposes described herein, (b)
Debtor will be the legal and beneficial owner of all of the Collateral, (c)
except as set forth on Exhibit B attached hereto, all of the Collateral will be
owned by Debtor free of any pledge, mortgage, lien, security interest or
encumbrance of any kind, except for the security interest granted herein, (d)
the execution and delivery by Debtor of this Agreement, and the performance of
its terms, will not result in any violation or default under the terms of any
agreement or instrument, or any law or governmental rule or regulation
applicable to Debtor or the Collateral, (e) upon execution and delivery by
Debtor of this Agreement, this Agreement shall create a valid security interest
in the Collateral, and the proceeds thereof, subject to no prior security
interest except as may set forth on Exhibit B, (f) as of the date hereof, and
after giving effect to this Agreement and the completion of all other
transactions contemplated by Debtor at the time of the execution of this
Agreement, Debtor is and will be solvent, (g) except as disclosed in writing to
Secured Party, Debtor is conducting Debtor's businesses in material compliance
with all applicable federal, state and local laws, statutes, ordinances, rules,
regulations, orders, determinations and court decisions, including without
limitation, those pertaining to health or environmental matters, and (h) if any
of the Collateral consists of Accounts, each Account is valid and enforceable
without performance by Debtor and is not subject to any contra accounts,
setoffs, defenses or counterclaims.

SECURITY AGREEMENT - Page 2

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      8. Affirmative Covenants. Debtor covenants and agrees to: (a) from time to
time promptly execute and deliver to Secured Party all such other assignments,
certificates, supplemental writings and financing statements, and do all other
acts or things, as the Secured Party may request in order more fully to evidence
and perfect the security interest herein created or to effect the purposes of
this Agreement; (b) punctually and properly perform all of the Debtor's
covenants and duties under any Loan Documents; (c) promptly furnish Secured
Party with any information or writings which Secured Party may request
concerning the Collateral; (d) allow Secured Party to inspect all records of
Debtor relating to the Collateral, and to make and take away copies of such
records, at the Debtor's expense, at such reasonable times and as often as may
be reasonably requested by Secured Party; (e) notify Secured Party of any change
in the location of the Collateral, Debtor's principal place of business and
mailing address prior to any such change, (f) promptly notify Secured Party of
any change in any fact or circumstance warranted or represented by Debtor in
this Agreement or in any other writings furnished by Debtor to Secured Party in
connection with the Collateral; (g) promptly notify Secured Party of any claim,
action or proceeding relating to the Collateral, or any part thereof or the
security interest therein, and, at the request of Secured Party, appear in and
defend, at Debtor's expense, any such action or proceedings; (h) promptly pay to
Secured Party the amount of all court costs and attorneys' fees incurred by
Secured Party hereunder; (i) fully perform all of Debtor's duties under and in
connection with each transaction to which the Collateral relate, so that the
amounts thereof shall actually become payable in their entirety to Debtor; (j)
promptly collect and enforce payment of the Collateral; (k) maintain the
Collateral in good repair, working order and condition; (1) pay, before
delinquent, all taxes and other assessments lawfully levied against the
Collateral; and (m) maintain good and marketable title to all Collateral free
and clear of all liens, security interests, encumbrances or adverse claims,
except for the security interest created by this Agreement and the security
interests and other encumbrances expressly permitted by this Agreement and the
other Loan Documents.

      9. Performance by Secured Party. Should any covenant, duty or agreement of
Debtor fail to be performed in accordance with its terms hereunder, Secured
Party may perform or attempt to perform such covenant, duty or agreement on
behalf of Debtor, and any amount expended by Secured Party in such performance
or attempted performance shall become a part of the Indebtedness, and, at the
request of Secured Party, Debtor agrees promptly to pay such amount to Secured
Party at Secured Party's office set forth below, provided that Secured Party
does not assume and shall never have any liability for the performance of any
duties of Debtor under or in connection with the Collateral, or any part
thereof, or under any transaction, agreement or contract out of which the
Collateral, or any part thereof, may arise. If any lessee, obligor or account
debtor of all or any part of the Collateral fails or refuses to make payment
thereon when due, Secured Party is authorized, in its discretion, either in its
own name or in the name of Debtor, to take such action as Secured Party shall
deem reasonably appropriate for the collection of the Collateral and any
proceeds thereof with respect to which a delinquency exists. Regardless of any
other provision hereof, however, Secured Party shall never be liable for its
failure to collect, or for its failure to exercise diligence in the collection
of any of the Collateral or any proceeds thereof, nor shall it be under any duty
whatsoever to anyone, except to account for the funds that it shall actually
receive hereunder.

      10. Negative Covenants. Debtor hereby covenants that, until such time as
the Indebtedness has been fully paid, performed and satisfied, Debtor will not:
(a) sell, convey, pawn or otherwise dispose of any of the Collateral or any
interest therein other than in the ordinary course of business; (b) create,
incur or permit to exist any pledge, mortgage, lien, charge, encumbrance or any
security interest whatsoever in or with respect to any of the Collateral, or the
proceeds thereof, other than the security interest created hereby and any
encumbrance or security interest expressly permitted by this Agreement and the
other Loan Documents; or (c) remove, or permit to be removed, Debtor's records
concerning the Collateral from Debtor's mailing address as specified in this
Agreement. Debtor covenants and agrees that Debtor will not use or permit the
Collateral which are inventory or equipment to be used for any unlawful purpose
or in any manner inconsistent with the provision or requirements of any policy
of insurance thereon.

      11. Indemnity. Debtor warrants to defend Secured Parry's right, title and
security interest in and to the Collateral against the claims of any person or
entity. Further, Debtor hereby indemnifies and agrees to hold harmless Secured
Party, and its officers, directors, employees, agents and representatives (each
an "Indemnified Person") from and against any and all liabilities, obligations,
claims, losses, damages, penalties, actions, judgments, suits, costs, expenses
or disbursements of any kind or nature which may be imposed on, incurred by, or
asserted against, any Indemnified Person (whether or not caused by any
Indemnified Person's sole, concurrent or contributory negligence)

SECURITY AGREEMENT - Page 3

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arising in connection with the Loan Documents or the Collateral (including
without limitation, the enforcement of the Loan Documents and the defense of any
Indemnified Person's actions and/or inactions in connection with the Loan
Documents).

      12. Event of Default. As used herein, the term "Event of Default" shall
mean the failure of timely payment and performance of any of the Indebtedness,
or any "default" or "event of default" as defined in any of the Loan Documents.

      13. Rights and Remedies. Upon the occurrence of an Event of Default, in
addition to all other remedies available to Secured Party, Secured Party may, at
Secured Party's option, without limitation and without notice except as
expressly provided in any of the Loan Documents: (a) exercise in respect of the
Collateral all the rights and remedies of a secured party under the Code; (b)
proceed immediately to have any or all of the Collateral transferred to Secured
Party's name, and Debtor hereby covenants that, in such event and upon Secured
Party's request, Debtor will take such actions as are necessary to effectuate
such transfer; (c) reduce its claim to judgment or foreclose or otherwise
enforce, in whole or in part, the security interest granted hereunder by any
available judicial procedure; (d) apply for the appointment of a receiver for
the Collateral; (e) retain the Collateral in satisfaction of the Indebtedness
whenever the circumstances are such that Secured Party is entitled to do so
under the Code or otherwise; or (f) proceed immediately to dispose of and
realize upon the Collateral, or any part thereof, and in connection therewith,
sell or otherwise dispose of and deliver the Collateral, or any part thereof, in
one or more parcels at public or private sale or sales, or at any of Secured
Party's offices or elsewhere, at such prices and on such terms as it may deem
best, for cash or on credit, or for future delivery without assumption of any
credit risk, with the right of Secured Party or any purchaser to purchase at any
such sale either the whole or any part of the Collateral (in connection with any
such sale or disposition, Secured Party need not give more than ten (10)
calendar days notice of the time and place of any public sale or of the time
after which a private sale may take place, which notice Debtor hereby
acknowledges to be reasonable). Debtor does hereby expressly waive any right to
any legal process of judicial hearing prior to such taking of possession by the
Secured Party. Debtor understands that the right to prior notice and hearing is
a valuable right and agrees to the waiver thereof as a part of the consideration
for and as an inducement to the Secured Party to enter into the loan
transaction.

      14. Application of Proceeds. The proceeds of any disposition of all or any
part of the Collateral may be applied by Secured Party in such order and manner
as Secured Party, in its discretion, deems appropriate including, without
limitation, the following order: (a) first, to the costs and expenses incurred
in connection with the disposition of the Collateral or incidental thereto,
including reasonable attorneys' fees and legal expenses; (b) second, at Secured
Party's election, to the payment or other satisfaction of any liens and other
encumbrances upon the Collateral; (c) third, to the satisfaction of the
Indebtedness; (d) fourth, to the payment of any other amounts required by
applicable law; and (e) fifth, to Debtor to the extent of any surplus remaining.
Debtor shall remain liable for any deficiency, which it shall pay to Secured
Party immediately upon demand.

      15. Waiver by Debtor. Except as expressly otherwise provided for herein,
Debtor hereby waives demand, presentment, presentment for payment, notice of
intent to demand, notice of nonpayment, notice of dishonor, diligence in
collecting, grace, notice (including notice of intent to accelerate and notice
of acceleration), protest and notice of protest. Debtor hereby further agrees
that no act or omission of Secured Party with reference to the Collateral,
including but not limited to failure to file or perfect any lien or security
interest, shall release Debtor from its obligations hereunder.

      16. Custody of Collateral. Should any part of the Collateral which is
Inventory or Equipment come into the possession of Secured Party, whether before
or after default, Secured Party may use or operate the Collateral for the
purpose of preserving it or its value, pursuant to the order of a court of
appropriate jurisdiction, or in accordance with any other rights held by Secured
Party in respect of the Collateral. Debtor covenants to promptly reimburse and
pay to Secured Party, all costs (including the cost of any insurance and payment
of taxes or other charges) incurred by Secured Party in connection with the
custody, preservation, use or operation of the Collateral, and all such
expenses, costs, taxes and other charges shall be a part of the Indebtedness. It
is agreed, however, that the risk of accidental loss or damage to the Collateral
is on Debtor, and Secured Party shall have no liability whatsoever for failure
to obtain or maintain insurance or to determine whether any insurance ever in
force is adequate as to amount or as to the risks insured.

SECURITY AGREEMENT - Page 4

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      17. Collection of Proceeds. Debtor agrees that upon the request of Secured
Party, Debtor shall establish and maintain at its sole expense, a non-interest
bearing deposit account styled as designated by Secured Party, with a financial
institution designated by Secured Party, into which Debtor shall deposit all
payments received by Debtor with respect to the Collateral, and over which
Secured Party shall have the exclusive authority to withdraw funds in the event
of a default hereunder. Upon notice of default from Secured Party, each account
debtor or other party obligated to Debtor is hereby authorized and directed by
Debtor to make all payments due to Debtor directly to Secured Party, and Debtor
agrees to notify and instruct all account debtors and other parties obligated to
Debtor that all payments made to Debtor shall be remitted, for the credit of
Debtor, to Secured Party. Upon the earlier of default or notice from Secured
Party, Debtor covenants and agrees that: (a) all cash proceeds of the Collateral
received by Debtor, whether in the form of cash, checks, or otherwise, shall be
segregated from all other funds of Debtor and be held in trust for Secured
Party, and each item of such proceeds, immediately upon receipt thereof by
Debtor shall become part of the Collateral; and (b) Debtor shall have absolutely
no dominion or control over any payment received in respect of the Collateral,
or any part thereof, except to deliver such payment immediately to Secured Party
properly endorsed, so that Secured Party may collect and apply the proceeds in
accordance with the terms hereof. Secured Party is authorized and empowered, on
behalf of Debtor, to endorse the name of Debtor upon any check, draft or other
instrument payable to Debtor evidencing payment upon the Collateral, or any part
thereof, and to receive and apply the proceeds therefrom in accordance with the
terms hereof. Secured Party is expressly granted a limited power of attorney by
Debtor for the purpose of endorsing Debtor's name as set forth hereinabove, such
limited power of attorney being an irrevocable power of attorney coupled with an
interest.

      18. Delivery of Notices. Debtor agrees to promptly deliver to Secured
Party a copy of all written notices received by Debtor with respect to the
Collateral or the Indebtedness.

      19. Termination Upon Performance. Upon full payment and performance of all
of the Indebtedness and upon payment of all additional costs and expenses
provided herein, this Agreement shall terminate.

      20. Filing of Financing Statement. Debtor authorizes Secured Party to file
in the name of and on behalf of Debtor all financing statements or other filings
deemed necessary or desirable by Secured Party to evidence, perfect, or continue
the security interests granted in this Agreement.

      21. Parties Bound. This Agreement is binding upon and shall inure to the
benefit of the parties hereto, and their heirs, administrators and assigns.

      22. GOVERNING LAW AND VENUE. THIS AGREEMENT HAS BEEN ACCEPTED AND IS
PERFORMABLE WITHIN DALLAS COUNTY, TEXAS, AND VENUE IN ANY ACTION ARISING OUT OF
THIS AGREEMENT SHALL LIE IN DALLAS COUNTY, TEXAS. THIS AGREEMENT SHALL BE
GOVERNED AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS AND
FEDERAL LAWS APPLICABLE TO THE STATE OF TEXAS.

      23. Transfer and Assignment. This Agreement and the security interest
created hereby shall be transferable and assignable by Secured Party in whole or
in part, at such times and upon such terms as it deems advisable and, upon any
such transfer or assignment, the transferee or assignee shall succeed to all
rights and powers of the Secured Party hereunder to the extent of any such
transfer or assignment.

      24. No Waiver by Secured Party. No waiver by Secured Party of any default
shall be deemed to be a waiver of any other subsequent default, nor shall any
such waiver by Secured Party be deemed to be a continuing waiver. No delay or
omission by Secured Party in exercising any right or power hereunder, or under
any of the other Loan Documents, shall impair any such right or power or be
construed as a waiver thereof or any acquiescence therein, nor shall any single
or partial exercise of any such right or power preclude other or further
exercise thereof, or the exercise of any other right or power of Secured Party
hereunder or under any of the Loan Documents.

      25. Cumulative Rights. All rights and remedies of the Secured Party
hereunder are cumulative of each other and of every other right or remedy which
Secured Party may otherwise have at law or in equity or under any other

SECURITY AGREEMENT - Page 5

<PAGE>

contract or document for the enforcement of the security interest herein or the
collection of the Indebtedness, and the exercise of one or more rights or
remedies shall not prejudice or impair the concurrent or subsequent exercise of
other rights or remedies provided in other instruments and agreements between
Debtor and Secured Party, or as provided by law, including without limitation,
the rights and remedies of a secured party under the Code.

      26. Notice. Any notice or other communication required or permitted
hereunder must be in writing and sent by U.S. Mail, registered or certified,
return receipt requested. Notice given under the above-described manner shall be
deemed to have been given and received when a registered or certified letter
containing such notice, properly addressed, with postage prepaid, return receipt
requested is deposited in the United States mail. Such notices shall be given to
the parties hereto at the following addresses:

      If to Debtor:          Drew Scientific, Inc.
                             4230 Shilling Way
                             Dallas, Texas 75237
                             Attn: Keith Drew

      If to Secured Party:   Texas Mezzanine Fund Inc.
                             351 West Jefferson Blvd., Suite 800
                             Dallas, Texas 75208
                             Attn: Theresa Lee

Each of the parties hereto shall be entitled to specify a different address by
giving written notice to the other party hereto in accordance with this
Paragraph.

      27. Modification. No term or condition of this Agreement shall be deemed
to have been waived nor shall there be any estoppel to enforce any provision of
this Agreement except by written instrument of the party charged with such
waiver or estoppel. No amendment or modification of this Agreement shall be
deemed effective unless and until executed in writing by both of the parties
hereto.

      28. Further Assurances. Debtor will execute, re-execute and/or initial any
such document or instrument as may be requested by Secured Party in order to (a)
correct any errors or omissions in this Agreement, whether such error or
omission is due to the unilateral mistake of Secured Party, mutual mistake on
the part of Secured Party and Debtor, clerical mistake, calculation error,
computer malfunction, printing error or similar error, or (b) perfect or give
further assurances of any of the rights, titles, liens or security interests
granted or provided for in this Agreement. Debtor further agrees that Secured
Party shall not be liable to Debtor for any damages incurred by Debtor that are
directly or indirectly caused by any such mistake, error or omission.

      29. Severability. All agreements and covenants contained herein are
severable and in the event that any of them shall be held to be invalid by any
court of competent jurisdiction, this Agreement shall be interpreted as if such
invalid agreements or covenants were not contained herein.

      30. Gender and Number. Where appropriate, the use of one gender shall be
construed to include the others or any of them; and the singular number shall be
construed to include the plural, and vice versa.

      31. FINAL AGREEMENT. THIS WRITTEN AGREEMENT REPRESENTS THE FINAL AGREEMENT
BETWEEN THE PARTIES WITH RESPECT TO THE SUBJECT MATTER HEREOF AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS
OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

SECURITY AGREEMENT - Page 6

<PAGE>

EXECUTED this 20th day of November, 2003.

                                 SECURED PARTY:

                                 TEXAS MEZZANINE FUND INC.,
                                 a Texas corporation

                                 By: /s/ Theresa Lee
                                     -----------------------
                                 Name: Theresa Lee
                                 Title: Vice-President

                                 DEBTOR:

                                 DREW SCIENTIFIC, INC.,
                                 a Texas corporation

                                 By: /s/ Keith Drew
                                     -----------------------
                                 Name: Keith Drew
                                 Title: President

SECURITY AGREEMENT - Page 7

<PAGE>

                                    Exhibit B
                 Permitted Liens/Security Interests/Encumbrances

1.    Financing Statement No. 99-156605 filed on August 3,1999 in the Office of
      the Secretary of State of the State of Texas, MWI, Inc. dba Danam
      Electronics, as debtor, Texas Mezzanine Fund, Inc., as secured party,
      covering all accounts, inventory and equipment, with security interest in
      (a) export related accounts and inventory subordinated to the security
      interest of Bank of America, N.A., and (b) domestic accounts and inventory
      subordinated to the security interest of Vertex Financial Corporation
      pursuant to Intercreditor Agreement by and among Texas Mezzanine Fund,
      Inc., Bank of America, N.A. and Vertex Financial Corporation dated March
      7, 2002, as amended.

2.    Financing Statement No. 00-520328 filed on June 12, 2000 in the Office of
      the Secretary of State of the State of Texas, MWI, Inc. dba Danam
      Electronics, as debtor, Bank of America, N.A., as secured party, covering
      all accounts, inventory and equipment, as amended by Financing Statements
      02-00199789, 02-00210790, 02-00277004 and 02-00302353.

3.    Financing Statement No. 0002038371 filed on December 5,2000 in the Office
      of the Secretary of State of the State of Connecticut, MWI, Inc. , as
      debtor, Associates Leasing, Inc., as secured party, covering one (1)
      Daewoo Mynx 500.

4.    Financing Statement No. 02-0024567117 filed on April 1, 2002 in the Office
      of the Secretary of State of the State of Texas, MWI, Inc., as debtor,
      Vertex Financial Corporation, as secured party, covering all domestic
      accounts and inventory, as amended by Financing Statement No. 03-00121476.

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