Exhibit 10.xlvi

Page 1

                      SCIENCE & TECHNOLOGY RESOURCES, INC.
                  A Subsidiary of Nevada Manhattan Mining, Inc.
                          643-B South Washington Street
                         Alexandria, Virginia 22314 USA

November 16, 1998

Phystechmed
117335 Moscow, Russia
Bolshaya Ordynka, 17-11
Tel/Fax 7095 243-06-91

         Re:      Letter of Understanding

Dear Professor Bogomolov:

     This  letter is intended  to  memorialize  the  agreement  we have  reached
relative to the acquisition by Science & Technology Resources,  Inc. ("STRI") of
100 percent of the rights,  title and  interest  to the  following  technologies
(collectively,  the "Technologies") owned by Phystechmed,  a joint stock company
located in Moscow, Russia:

     1.   20 MeV Proton (or heavcy  particle)  accelerator  using  Backward Wave
          Acceleration Acceleration principle (Bogomolov)

     2.   10 (to 12) MeV injectors.

     3.   250 MeV Proton Accelerators (Bogomolov); medical model.

     4.   Explosives detection equipment.

     Subject to the completion of its due diligence, corporate and/or regulatory
approvals and if it deems  necessary,  a more formal  agreement,  STRI agrees to
acquire the sole and exclusive  rights,  title and interest to the Technologies.
In  consideration  therefore,  STRI agrees to pay Phystechmed  and/or  designees
royalties  and/or  Preferred  Stock of STRI,  in an amount and under terms to be
agreed upon by the parties to this agreement,  after  completion of thorough due
diligence and a financial assessment.

Very truly yours,

STRI

/s/ Thomas E. Ward

Thomas E. Ward
President

         AGREED AND ACCEPTED, this 30 day of November, 1998, with full power and
authority  from  Phystechmed,  to enter into and execute  this  agreement on its
behalf.

                                                 PHYSTECHMED

                                                 by General Manager, CEO

                                                   /s/ Y. Yushkevich

                                                     Y. Yushkevich