Document:

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EXHIBIT 10.4

                                 PROMISSORY NOTE

U.S. $375,000.00                                             Baltimore, Maryland
                                                              September __, 2003

         FOR VALUE RECEIVED, the undersigned, STR Acquisition, Corp., a Maryland
corporation with a mailing address of _______________________ ("OBLIGOR"),
promises to pay to George Yang, a Maryland resident with a mailing address of
_________________ ("OBLIGEE"), the principal sum of Three Hundred Seventy-Five
Thousand and No/100 ($375,000.00) Dollars, with no regular interest on such
principal amount.

         The principal on this Promissory Note shall be payable as follows: a
principal payment in the amount of Ninety-Three Thousand Seven Hundred Fifty and
No/100 Dollars ($93,750.00), shall be due 150 days after the "AGREEMENT DATE" as
set forth in the "AGREEMENT AND PLAN OF MERGER" by and among Obligor, Markland
Technologies, Inc. (Obligor's 100% parent corporation, "PARENT"), Security
Technology, Inc. another wholly owned subsidiary of Parent, Obligee and Science
and Technology Research, Inc. (a corporation, all the outstanding capital stock
of which is owned by Obligee) dated on even date herewith, a second principal
payment in the amount of One Hundred Twenty-Five Thousand and No/100 Dollars
($125,000.00), shall be due 210 days after the Agreement Date, a third principal
payment in the amount of Seventy-Eight Thousand One Hundred and Twenty Five and
No/100 Dollars ($78,125.00), shall be due 270 days after the Agreement Date, the
fourth and final principal payment in the amount of Seventy-Eight Thousand One
Hundred and Twenty Five and No/100 Dollars ($78,125.00), shall be due 360 days
after the Agreement Date.

         Whenever a day on which payment of principal required to be made
hereunder falls on a Saturday, Sunday or public holiday (on which banks in New
York City are closed), such payment shall be due on the next following normal
business day, and where time is extended for the payment of principal by virtue
of the due date thereof falling on a Saturday, Sunday or public holiday, such
extended time shall be included in the computation of interest.

         Principal shall be paid to Obligee at his mailing address first set
forth above, or at such other address as the Obligee may specify in writing to
the Obligor. Payment shall be made by means of a check or wire transfer in
immediately available funds to be received by Obligee on or before the relevant
due date. Principal that is not paid when due under this Promissory Note shall
be subject to default interest at a rate of twelve percent (12%) per annum.

         At the option of the Obligee, the entire outstanding principal balance
of this Promissory Note shall at once become due and payable in full upon the
occurrence, at any time, of any of the following events (each referred to as an
"EVENT OF DEFAULT"); PROVIDED, HOWEVER, that an event set forth in clauses (i)
or (ii) below shall not become an Event of Default if it is cured by Obligor
within five (5) days of receipt of Obligee's written notice of the same
(provided that no notice of nonpayment is required if the same occurs more than
twice in any twelve month period):

                  (i) Obligor shall fail to make any payment of principal on
         this Promissory Note when and, as the same shall become due and
         payable;

                  (ii) A breach by Obligor of any representation, warranty,
         covenant or any other material term of the Agreement and Plan of Merger
         of even date herewith, the Security Agreement of even date herewith
         between the parties, or any other instruments, documents and agreements
         made and entered into contemporaneous therewith, pursuant thereto or in
         connection therewith (the "DOCUMENTS");

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                  (iii) An event of default as described in any instrument
         evidencing any indebtedness of the Obligor to the Obligee or any third
         party and the expiration of any period provided in such instrument to
         cure such default;

                  (iv) Obligor shall institute proceedings to be adjudicated
         voluntary bankrupt, or shall consent to the filing of a bankruptcy
         proceeding against it, or shall file a petition seeking reorganization
         or arrangement of similar relief under the federal or state bankruptcy
         or insolvency laws now or hereafter existing, including receivership or
         assignment for the benefit of creditors, or if any involuntary
         proceeding is filed against Obligor which shall not be vacated, set
         aside or stayed within sixty (60) days from the date said involuntary
         proceeding is filed, or effecting a reorganization or arrangement
         pursuant to said bankruptcy or insolvency laws;

                  (v) The sale by Obligor of substantially all of its assets,
         without the prior written consent of the Obligee, which consent shall
         be in Obligee's sole discretion;

                  (vi) The occurrence of an event of default as described and
         defined in one or more of the Documents, which event is not cured
         within the time frame allowed therein, if any, for cure; and

                  (vii) The Obligor shall cease all business operations.

         Obligor expressly waives notice of non-payment, presentment, demand for
payment, or protest. Obligor agrees to pay the Obligee a late charge equal to an
additional five percent (5%) of any payment due to the Obligee that is not
received within five (5) days after the same is due.

         The failure of Obligee at any time or times hereunder to require strict
performance by the Obligor of any of the provisions, warranties, terms and
conditions contained in this Promissory Note or in any other agreement,
guaranty, instrument, or document now or at any time or times hereafter executed
by the Obligor and delivered to Obligee shall not waive, affect, or diminish any
right of Obligee at any time or times to demand strict performance thereof; and
no rights of Obligee hereunder shall be deemed to have been waived by any act or
knowledge of Obligee, its agents, officers, or employees, unless such waiver is
contained in an instrument in writing signed by Obligee and directed to the
Obligor specifying such waiver. No waiver by Obligee of any of its rights shall
operate as a waiver of any other of its rights on a future occasion.

         In the event of any default hereunder, the Obligor agrees to pay all
reasonable costs of collection including reasonable attorney's fees, for the
Obligee for all services rendered in that connection.

         Any notice to Obligor provided for in this Promissory Note shall be
given by mailing such notice, certified mail, return receipt requested,
addressed to Obligor, or at such other address as Obligor may designate by
written notice to the Obligee. Any notice to the Obligee shall be given by
mailing such notice, certified mail, return receipt requested, addressed to
Obligee, or at such other address as Obligee may designate by written notice to
the Obligor. Any notice issued in accordance with this Promissory Note shall be
effective on date of receipt.

         This Promissory Note is entered into and made pursuant to the laws of
the State of Maryland and shall in all respects be governed, construed, applied
and enforced in accordance with the laws of said State of Maryland.

         Obligee and any successor holder may assign, transfer or negotiate this
Promissory Note and any security for the performance of Obligor's obligations
hereunder, and in such event all the provisions of this Promissory Note and the
security instruments shall inure to the benefit of and may be exercised by or on
behalf of the successor holder.

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         OBLIGOR AND, BY THEIR ACCEPTANCE OF THIS PROMISSORY NOTE, OBLIGEE AND
ANY SUBSEQUENT HOLDER OF THIS PROMISSORY NOTE, HEREBY IRREVOCABLY AGREE TO WAIVE
THEIR RESPECTIVE RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED
UPON OR ARISING OUT OF THIS PROMISSORY NOTE OR ANY DEALINGS BETWEEN THEM
RELATING TO THE SUBJECT MATTER OF THIS PROMISSORY NOTE. The scope of this waiver
is intended to be all encompassing of any and all disputes that may be filed in
any court and that relate to the subject matter of this transaction, including
without limitation contract claims, tort claims, breach of duty claims and all
other common law and statutory claims. Obligor and, by their acceptance of this
Promissory Note, Obligee and any subsequent holder of this Promissory Note, each
(i) acknowledges that this waiver is a material inducement to enter into a
business relationship, that each has already relied on this waiver in entering
into this relationship, and that each will continue to rely on this waiver in
their related future dealings and (ii) further warrants and represents that each
has reviewed this waiver with its legal counsel and that each knowingly and
voluntarily waives its jury trial rights following consultation with legal
counsel. THIS WAIVER IS IRREVOCABLE, MEANING THAT IT MAY NOT BE MODIFIED EITHER
ORALLY OR IN WRITING, AND THIS WAIVER SHALL APPLY TO ANY SUBSEQUENT AMENDMENTS,
RENEWALS, SUPPLEMENTS OR MODIFICATIONS OF THIS PROMISSORY NOTE. In the event of
litigation, this provision may be filed as a written consent to a trial by the
court.

EXECUTED AS A SEALED INSTRUMENT
-------------------------------

In the Presence Of:                          OBLIGOR:

                                             STR ACQUISITION CORP.

                                             By: /s/ Ken Ducey
----------------------------                     -------------------------------
                                                 Ken Ducey, CFO/President

----------------------------

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EXHIBIT 10.5

                                 PROMISSORY NOTE
                                 ---------------

$1,400,000.00                                           Providence, Rhode Island
                                                             September ___, 2003

         FOR VALUE RECEIVED, the undersigned and each of them, jointly and
severally, unconditionally promise to pay to BAY VIEW CAPITAL L.L.C., a Rhode
Island limited liability company ("Lender"), or order, at its offices at 5600
Post Road, No. 114-372, East Greenwich, RI 02818, or at such other place as may
be designated in writing by the holder hereof, the principal sum of ONE MILLION
FOUR HUNDRED THOUSAND AND 00/100 ($1,400,000.00) DOLLARS, or such lesser
aggregate principal sum as may be advanced by Lender pursuant to that certain
Loan Agreement between each of the undersigned and Lender of even date herewith
(as the same may be amended and/or restated from time to time, the "Loan
Agreement"), together with interest in arrears from the date hereof on the
unpaid principal balance hereunder, at the rate of TWELVE AND 00/100 (12.00%)
percent per annum, subject to adjustment as hereinafter provided. Interest on
the unpaid principal balance hereof shall be computed daily on the basis of the
actual number of days elapsed over a year of 360 days.

         All accrued interest on the unpaid principal balance hereunder shall be
paid monthly, in arrears, commencing on and including November ____, 2003, and
continuing on the same day of each successive month thereafter, or the next
business day thereafter if such day is not a business day, through and including
October ____, 2005, with a final payment of all accrued and unpaid interest to
be made contemporaneously with the payment in full of the principal balance
hereof.

         Outstanding principal shall be payable monthly contemporaneously with
the payment of interest, in an amount equal to twenty-five (25%) percent of the
gross revenue of Science & Technology Research, Inc., a Maryland corporation,
for the immediately preceding calendar month. The entire principal balance
hereof together with any interest, charges or other amounts outstanding
hereunder, if not sooner paid, shall be due and payable in full on September __,
2005 (the "Maturity Date").

         This note may be prepaid in whole or in part at any time without
penalty or premium.

         If any amount of principal and/or interest hereunder is not paid in
full within five (5) days of the date on which the same shall be due, the
undersigned shall pay to Lender a late fee on such unpaid amount equal to five
(5%) percent of such late payment. From and after the occurrence of an Event of
Default (as hereinafter defined), the entire outstanding balance hereunder shall
bear interest, at the option of the holder hereof, at the rate of Eighteen and
00/100 (18%) percent per annum ("Default Rate").

         All payments received hereunder shall be applied first to the payment
of accrued interest and any expenses or charges payable hereunder and the
balance only applied to principal. All agreements between the undersigned and
Lender are hereby expressly limited so that in no contingency or event
whatsoever, whether by reason of acceleration of maturity of the indebtedness
evidenced hereby or otherwise, shall the amount paid or agreed to be paid to
Lender for the use or the forbearance of the indebtedness evidenced hereby
exceed the maximum permissible under applicable law. As used herein, the term
"applicable law" shall mean the law in effect as of the date hereof provided,

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however, that in the event there is a change in the law which results in a
higher permissible rate of interest, then this Note shall be governed by such
new law as of its effective date. In this regard, it is expressly agreed that it
is the intent of the undersigned and Lender in the execution, delivery and
acceptance of this Note to contract in strict compliance with the laws of the
State of Rhode Island from time to time in effect. If, under or from any
circumstances whatsoever, fulfillment of any provision hereof, or of any
document, instrument or agreement executed in connection herewith or related
hereto, at the time of performance of such provision shall be due, shall involve
transcending the limit of such validity prescribed by applicable law, then the
obligation to be fulfilled shall automatically be reduced to the limits of such
validity, and if under or from circumstances whatsoever Lender should ever
receive as interest an amount which would exceed the highest lawful rate, such
amount which would be excessive interest shall be applied to the reduction of
the principal balance evidenced hereby and not to the payment of interest. This
provision shall control every other provision of all documents, instruments and
agreements between the undersigned and Lender.

         Each of the undersigned, any indorser hereof, any other party hereto
and any guarantor hereof (individually an "Obligor" and collectively
"Obligors"): (i) waives presentment, demand, notice of demand, protest, notice
of protest and notice of nonpayment and any other notice required to be given
under the law to any of Obligors in connection with the delivery, acceptance,
performance, default or enforcement of this note, any indorsement or guaranty of
this note or any document or instrument evidencing any security for payment of
this note; (ii) consents to any and all delays, extensions, renewals or other
modifications of this note or waivers of any term hereof or release or discharge
by Lender of any of Obligors or release, substitution or exchange of any
security for the payment hereof or the failure to act on the part of Lender or
any other indulgence shown by Lender from time to time and in one or more
instances (without notice to or further assent from any of Obligors) and agrees
that no such action, failure to act or failure to exercise any right or remedy
on the part of Lender shall in any way affect or impair the obligations of any
Obligor or be construed as a waiver by Lender of, or otherwise affect, any of
Lender's rights under this note, under any indorsement or guaranty of this note
or under any document or instrument evidencing any security for payment of this
note; and (iii) jointly and severally agrees to pay, on demand, all costs and
expenses of collection of this note or of any indorsement or any guaranty hereof
and/or the enforcement of Lender's rights with respect to, or the
administration, supervision, preservation, protection of, or realization upon,
any property securing payment hereof, including reasonable attorneys' fees, and
agrees that Lender shall have the right to set-off without notice any and all
sums at any time owed by or due from Lender to any of Obligors, whether or not
matured.

         Each of the following shall constitute an Event of Default hereunder
("Event of Default"): (i) the failure of the undersigned to make any payment of
principal or interest hereunder within five (5) days of the date on which the
same shall be due, or (ii) the occurrence of an Event of Default, as defined and
described in the Loan Agreement. Upon the occurrence of an Event of Default, the

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entire balance outstanding hereunder and all other liabilities of Obligors or
any of them to Lender (however acquired or evidenced) shall, at the option of
the holder hereof, become forthwith due and payable, without presentment,
notice, protest or demand of any kind (all of which are expressly waived by
Obligors and each of them) for the payment of the whole or any part hereof.
Failure at any time to exercise any of the aforesaid options or any other rights
of Lender hereunder or under the Loan Agreement shall not constitute a waiver
thereof, nor shall it be a bar to exercise of any of the aforesaid options or
rights at a later date.

         This Note is delivered in and shall be governed by and construed and
enforced under the laws of the State of Rhode Island, without reference to
conflict of laws principles. ANY LITIGATION IN CONNECTION WITH OR RELATING TO
THIS NOTE OR THE ENFORCEMENT OF THIS NOTE OR ANY INDORSEMENT OR GUARANTY OF THIS
NOTE OR ANY SECURITY GIVEN FOR PAYMENT HEREOF SHALL BE BROUGHT ONLY IN A COURT
HAVING JURISDICTION AND VENUE AT PROVIDENCE, RHODE ISLAND, AND EACH OF OBLIGORS
CONSENTS TO AND CONFERS PERSONAL JURISDICTION ON ANY SUCH COURT OR COURTS. IN
ADDITION, EACH OF THE UNDERSIGNED AND LENDER, BY ACEPTANCE OF THIS NOTE,
KNOWINGLY, VOLUNTARILY AND IRREVOCABLY WAIVES THE RIGHT TO A TRIAL BY JURY IN
RESPECT OF ANY CLAIM BASED HEREON, ARISING OUT OF, UNDER OR IN CONNECTION WITH
THIS NOTE OR ANY OTHER DOCUMENTS, INSTRUMENTS OR AGREEMENTS CONTEMPLATED TO BE
EXECUTED IN CONNECTION HEREWITH OR ANY COURSE OF CONDUCT, COURSE OF DEALINGS,
STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF ANY PARTY. THIS WAIVER
CONSTITUTES A MATERIAL INDUCEMENT FOR LENDER TO ACCEPT THIS NOTE AND MAKE THE
LOAN EVIDENCED HEREBY. The term "Lender" shall include Lender's successors,
indorsees and assigns.

WITNESS:                                MARKLAND TECHNOLOGIES, INC.

                                        By:  /s/ Ken Ducey, Jr.
------------------------------              ------------------------------------
                                        Title: President

WITNESS:                                SECURITY TECHNOLOGY, INC.

                                        By:  /s/ Ken Ducey, Jr.
------------------------------              ------------------------------------
                                        Title: President

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