Document:

EXHIBIT 10.4

                                Schedule 1.02(a)
                                       to
                            Stock Purchase Agreement

                                   LEXON, INC.
                                 PROMISSORY NOTE

$150,000                                                         Tulsa, Oklahoma
                                                                January 28, 2000

         FOR VALUE RECEIVED,  LEXON, INC. hereby promises to pay to the order of
UTEK CORPORATION ("UTEK") the principal amount of One Hundred and Fifty Thousand
and no/100 Dollars ($150,000) plus interest as provided herein.

         1.  Maturity.  This Note and all accrued but unpaid  interest  shall be
paid in 3 equal consecutive monthly principal payments of $50,000 each beginning
on or before April 30, 2000 and  continuing on or before May 31, 2000, and on or
before June 30, 2000, respectively.

         2. Interest  Rate.  This Note shall bear interest until maturity at the
rate of 10% per annum and thereafter the unpaid  principal  balance of this Note
shall bear interest at the rate of 12% per annum.

         3. Maximum Interest Rate.  Notwithstanding  any provision herein,  UTEK
shall never be  entitled to receive,  collect or apply as interest on any amount
owed  hereunder  any amount in excess of the  maximum  lawful  rate of  interest
permitted  to be charged  by any  applicable  law.  In the event UTEK shall ever
receive,  collect  or apply as  interest  any  amount in  excess  of any  amount
permitted to be received under  applicable law, all such excess amounts shall be
applied as of the date  received to the  reduction  of the  principal  amount of
indebtedness hereunder. After payment of the indebtedness in full, all remaining
excess amounts paid shall forthwith be returned within five (5) days to LEXON.

         4. Permissive  Prepayment.  This Note and all  indebtedness  arising in
connection herewith may be prepaid at any time and from time to time in whole or
in part by LEXON without premium, penalty or other charges or fees whatsoever.

         5.  Application  of  Payments.  All payments  against the  indebtedness
arising under this Note shall be applied first to costs of collection, second to
accrued but unpaid interest and the balance to unpaid principal.

         6. Collateral.  The  indebtedness  evidenced by this Note is secured by
that certain Pledge and Security Agreement  ("Pledge  Agreement") given by LEXON
in favor of UTEK of even date herewith.  This Note is non-recourse  except as it
relates to the Collateral and the Pledged Shares under the Pledge Agreement.

         7.  Events of Default.  At the option of UTEK , this Note shall  become
immediately  due and payable upon the occurrence and during the  continuation of
the following events of default:

               (a) LEXON fails to pay  principal or interest  within 15 business
days after LEXON receives written notice of such payment default;

               (b) LEXON shall:

                    (1)  Be adjudicated a bankrupt or insolvent; or

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                    (2)  Admit in writing its  inability  to pay  LEXON's  debts
                         generally as they become due; or

                    (3)  Apply for or consent to the  appointment of a receiver,
                         trustee,   or   liquidator   of  LEXON  or  of  all  or
                         substantially all of LEXON's assets; or

                    (4)  File a voluntary  petition in  bankruptcy or a petition
                         or an answer seeking  reorganization  or an arrangement
                         with  creditors or take  advantage of or seek any other
                         relief    under   any    bankruptcy,    reorganization,
                         rearrangement, debtor's relief, or other insolvency law
                         now or hereafter existing; or

                    (5)  File an answer  admitting the material  allegations of,
                         or  consenting  to,  or  failure  to  answer  timely  a
                         petition   filed  against  LEXON  in  any   bankruptcy,
                         reorganization,   rearrangement,  debtor's  relief,  or
                         other insolvency proceedings; or

                    (6)  Institute  or  voluntarily  be or become a party to any
                         other  judicial   proceedings   intended  to  effect  a
                         discharge of all or substantially all of LEXON's debts,
                         in whole or in part, or a postponement  of the maturity
                         or the  collection  thereof,  or a suspension of any of
                         the rights or powers granted hereby; or

                (c) An order,  judgment, or decree shall be entered by any court
of competent  jurisdiction  approving a petition seeking reorganization of LEXON
or  appointing  a  receiver,  trustee,  or  liquidator  of  LEXON  or of  all or
substantially  all of its  assets,  and such order,  judgment,  or decree is not
permanently stayed or reversed within sixty (60) days after entry thereof; or

                (d) A petition is filed against LEXON seeking reorganization, an
arrangement   with  creditors,   or  any  other  relief  under  any  bankruptcy,
reorganization,  rearrangement,  debtor's relief, or other insolvency law now or
hereafter  existing,  and such petition is not discharged within sixty (60) days
after the filing thereof.

         If one or more events of default shall occur and be  continuing,  after
the expiration of any grace or curative period provided herein, UTEK may, at its
option,  declare the entire  indebtedness  arising hereunder due and payable and
may proceed to protect and enforce any and all rights to enforce  payment of all
indebtedness  arising  hereunder at law or in equity.  All rights,  remedies and
powers  conferred  upon UTEK herein shall be cumulative and not exclusive of any
other  rights,  remedies or powers.  No delay or omission to exercise any right,
remedy  or power  shall  impair  any  such  right,  remedy  or power or shall be
construed  to be a  waiver  of any  event  of  default  or any  acquiescence  or
forbearance with respect thereto.  Any right,  remedy or power granted hereunder
or  applicable  under  law or in  equity  may be  exercised  from  time to time,
independently  or  concurrently.  No waiver of any event of default shall extend
any other  subsequent  event of  default.  No single or partial  exercise of any
right, remedy or power shall preclude the exercise of any other right, remedy or
power or the further exercise thereof.

         8.  Governing  Law.  This  Note  has been  executed  and  delivered  in
Hillsborough  County,  Florida  and  shall  be  governed  by  and  construed  in
accordance with the laws of the State of Florida. UTEK expressly agrees that the
courts of Florida shall have  jurisdiction  over all  proceedings  in connection
herewith,  and LEXON agrees that for purposes of  enforcement  of UTEK 's rights
and

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remedies  hereunder,  venue and personal  jurisdiction  are proper in the courts
situated  in  Hillsborough  County,  Florida.  LEXON  waives any right to a jury
trial.

         9.  Severability.  In the event  any  provision  of this Note  shall be
declared by a court of competent jurisdiction to be unenforceable or invalid for
any  reason  whatsoever,  the  remaining  provisions  of this Note  shall not be
affected  thereby  and all such  remaining  provisions  shall be enforced to the
maximum extent permitted by law.

         10. Costs of Collection. If this Note or any portion hereof is not paid
when due, after  expiration of all curative  periods,  LEXON promises to pay all
reasonable  costs of  collection,  including but not limited to, all  reasonable
attorneys' fees, court costs and reasonable  expenses  incurred in good faith by
UTEK in order to obtain  prompt,  punctual and proper  payment of all amounts of
indebtedness arising hereunder.

         11. Waiver. LEXON and all other parties now or hereafter liable for the
payment of the indebtedness arising hereunder,  whether as endorser,  guarantor,
surety or otherwise,  waive  demand,  presentment,  diligence in collecting  and
consent to all extensions which from time to time may be granted.

         12.  Binding  Effect.  This  Note  and  all  the  covenants,  promises,
obligations  and  agreements  of LEXON and all rights,  powers,  privileges  and
entitlements  of UTEK  shall be binding  upon and inure to the  benefit of their
respective successors, legal representatives, and permitted assigns.

         13.  Currency  and Place of  Payment.  All  payments of  principal  and
interest  arising in connection  with this Note shall be made in lawful currency
of the United States of America and shall be paid to UTEK at 202 Wheeler Street,
Plant City,  Florida 33566 or such other place as UTEK shall  instruct  LEXON in
writing.

                                             LEXON, INC.

                                             By  /s/ GIFFORD MABIE
                                             Gifford Mabie, President

                                       3EXHIBIT 10.5

                                Schedule 1.02(b)
                                       to
                            Stock Purchase Agreement

                          PLEDGE AND SECURITY AGREEMENT

Secured Party Name and Address               Debtor's Name and Address

UTEK CORPORATION                             LEXON, INC.
202 Wheeler Street                           8908 South Yale, Suite 409
Plant City, Florida 33566                    Tulsa, Oklahoma 74137-3545
("Secured Party")                            ("Debtor")

         As of  the  date  indicated  above,  the  undersigned  Debtor  and  the
undersigned  Secured  Party,  with  addresses  as they appear  herein,  agree as
follows:

         1. Grant of Security Interest. For value received, Debtor, LEXON, INC.,
an Oklahoma  corporation,  grants to UTEK  CORPORATION,  Secured  Party, a first
prior security  interest in the pledged  shares and the collateral  described in
Paragraph 2 ("Collateral") to secure the obligations of Debtor to Secured Party,
pursuant to that certain  Secured  Promissory  Note ("Note")  dated of even date
herewith.

         2.  Collateral.  The  Collateral  consists  of 1,000  shares  ("Pledged
Shares") of Common Stock of Cancer  Diagnostics,  Inc.  ("CDI") which represents
all the issued and outstanding  shares of CDI common stock.  The Collateral also
includes all proceeds from the sale of such Collateral. The Pledged Shares shall
be  issued  in the name of Debtor or duly  endorsed  for  transfer  to Debtor or
endorsed in blank.

         3. Escrow of The Pledged Shares.  The Pledged Shares shall be delivered
to Sam Reiber,  Esquire,  in escrow ("Escrow Agent"),  who hereby agrees to hold
the  Pledged  Shares for the benefit of Debtor and either  surrender  possession
thereof  upon full  payment of the Note or return the Pledged  Shares to Secured
Party  upon the  demand of Secured  Party  during an event of default  under the
Note, after the giving of all notices required in the Note and hereunder and the
expiration of all grace periods hereunder and under the Note.

         4. Dividends and Voting Pledged  Shares.  While the Note remains unpaid
and not in default,  Debtor  shall be entitled  to receive  all  dividends  with
respect to and to vote all the Pledged Shares. So long as this Agreement and the
Note are not in default,  Debtor  shall be entitled to attend all  meetings,  to
vote the  Pledged  Shares  and  consent  to  shareholder  actions  in their sole
discretion  and to  enjoy  and  exercise  all the  rights  of  ownership  of the
Collateral, except that the Pledged Shares shall not be sold by Debtor until the
Note is paid in full.

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         5.  Negative  Covenant  of Debtor.  While the Note  remains not paid in
full, neither Debtor nor CDI will make any distributions of money or property to
its principal founding shareholders,  directors, or officers,  whether as loans,
cash  dividends,  repayment  of loans or  otherwise,  other than the  payment of
reasonable compensation for services rendered.

         6. Release of Pledged Shares.  Upon payment in full of the Note and all
interest and other  obligations  payable by Debtor under the Note,  the security
interest  hereby created shall ve released  automatically  and all  certificates
representing  the Pledged  Shares and all other rights,  titles and interests in
and to the Pledged Shares shall return and deliver to Debtor.

         7. No Transfer of Pledged Shares. While the Note remains unpaid, Debtor
shall not have the right, power or authority to sell,  assign,  pledge or convey
the Pledged Shares or any interest in the Pledged Shares without Secured Party's
prior written consent,  so long as the security  interest hereby created remains
in effect.

         8.  Representations  and Warranties  with regard to the Pledged Shares.
Debtor  represent  and warrant to Secured Party that Debtor has full legal power
to grant to Secured Party the security  interest  hereby  granted in the Pledged
Shares as herein provided.

         9. Events of Default.  Debtor shall be in default under this  Agreement
upon the happening of any of the following  events or conditions,  herein called
"Events of Default":

          (a)  Default  in the  payment  of any  liability  of Debtor to Secured
               Party under the Note; or

          (b)  Any event which  results in the  acceleration  of the maturity of
               the Note; or

          (c)  Any Event of Default under the Note.

         10. Remedies with Respect to Pledged Shares. During the continuation of
any Event of Default:

          (a)  Secured  Party  may,  with 15 days'  written  notice  to  Debtor,
               declare  all   obligations   of  Debtor  under  the  Note  to  be
               immediately due and payable; and

          (b)  Secured  Party  shall be  entitled  to  proceed  on its  security
               interest in the  Pledged  Shares in  accordance  with the Uniform
               Commercial  Code then in effect in Florida,  by giving  Debtor at
               least 15 days' prior notice  thereof;  provided  however,  Debtor
               shall cooperate and use all reasonable  efforts to assist Secured
               Party  in   foreclosing   upon  its  security   interest  in  the
               Collateral,  including  without  limitation,  consenting  to  the
               appointment of a receiver.

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         (c)      Secured  Party  will be  entitled  to  recover  all costs plus
                  reasonable  attorneys'  fees  and  expenses  and the  fees and
                  expenses  of a  receiver,  if one is  appointed,  incurred  in
                  holding the Pledged Shares and enforcing its rights  hereunder
                  before   applying  the  balance  of  any  proceeds   from  the
                  disposition  of the  Pledged  Shares  to the  satisfaction  of
                  Debtor's obligations under the Note.

         (d)      Secured  Party will have the right to  transfer  any or all of
                  the  Pledged  Shares  into  the  name  or the  name  of  their
                  nominees,  and shall be under a duty,  to exercise such rights
                  and privileges as required by law.

         11.  Governing Law. The law governing  this secured  transaction is the
State of Florida. For words or phrases defined in the Florida Uniform Commercial
Code, the Code definition will control their meaning.  A determination  that any
provision  contained  herein  is not  enforceable  will  have no  effect  on the
validity of the remaining provision.

         12.  Obligations  of Debtor  Secured by this  Agreement.  The  security
interest  herein granted is given to secure all of the  obligations of Debtor to
Secured Party under the Note and all extensions and renewals of liabilities  for
any term or terms,  all  interest  due or to become  due on the  liabilities  of
Debtor to Secured  Party under the Note,  and all costs,  attorneys'  fees,  and
other  expenditures of Secured Party in the collection and/or enforcement of any
obligation or liability of Debtor to Secured Party thereunder.

         13.  Expenditures of Secured Party.  Debtor is liable for and agrees to
pay Secured Party all expenditures of Secured Party for taxes of Collateral, and
all  costs,  attorneys'  fees and other  expenditures  of  Secured  Party in the
enforcement  or collection of the Note. All rights and remedies of Secured Party
hereunder are  cumulative  of all other rights or remedies  provided by law, and
may be exercised singularly or concurrently; and the exercise of any one or more
of them will not be a waiver of any other.  No waiver,  change,  modification or
discharge of any of Secured Party's rights or Debtor's duties as so specified or
allowed will be effective  unless  contained in a written  instrument  signed by
Secured Party.

         14. Waivers. No act, delay,  omission, or course of action by Debtor or
Secured Party, including Secured Party's waiver of remedy because of any default
hereunder,  will  constitute  a waiver  of any of  Secured  Party's  rights  and
remedies under this  Agreement or any other  agreement  between the parties,  or
under the documents evidencing the liabilities secured hereby. Waiver by Secured
Party of any  rights  or  remedies  under the  terms of this  Agreement  or with
respect to any of Debtor's liabilities to Secured Party will not be a bar to the
exercise  of any right or remedy on any  subsequent  occasion.  All  rights  and
remedies of Secured  Party are  cumulative  and may be exercised  singularly  or
concurrently,  and the  exercise of any one or more of them will not be a waiver
of any other.  No waiver,  change,  modification  or discharge of any of Secured
Party's  rights of Debtor's  duties as so specified or allowed will be effective
unless in writing and signed by Secured Party.

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         15. Agreement  Binding on Successors and Assigns.  This Agreement shall
be binding upon the heirs, executors, administrators,  successors and assigns of
the parties hereto.

SECURED PARTY                                DEBTOR
UTEK CORPORATION                             LEXON, INC.

By: /s/ DR. CLIFFORD GROSS                   By /s/ GIFFORD MABIE
Dr.  Clifford Gross                          Gifford Mabie, President
Chairman and Chief Executive Officer

                                             ESCROW AGENT:

                                             /s/ SAM REIBER
                                             Sam Reiber, Escrow Agent

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