Document:

<PAGE>   1

                                                                   Exhibit 10.50

                              Repayment Agreement*

This Agreement is made in Haidian District, Beijing on August 16, 2001 among the
following parties:

Daniel Mao (Passport No.:  147356158);
Yan Wang (ID No.:  110108720523143);
Yuanchao Yan (ID No.:  110102195110262316);
Huai Lin (ID No.:  110108490903224);
Jie Wang (ID No.:  110108620528223);
Danhong Lin (ID No.:  110108620806184); and
Beijing Stone Rich Sight Information Technology Co., Ltd., with official address
being: A1 Wanquanzhuang, Haidian District, Beijing (hereinafter "BSRS").

Whereas:

A. Zhidong Wang entered into a three-year term loan agreement with BSRS on
October 18, 1999. Pursuant to the said loan Agreement, Zhidong Wang has borrowed
RMB700,000 from BSRS to invest in the establishment of Beijing SINA Internet
Information Services Co., Ltd.
(hereinafter "ICP Company").

B. Yan Wang entered into a three-year term loan agreement with BSRS on October
18, 1999. Pursuant to the said loan agreement, Yan Wang has borrowed RMB300,000
from BSRS to invest in the establishment of the ICP Company.

C. The ICP Company was 70% owned by Zhidong Wang and 30% owned by Yan Wang right
after its establishment.

D. Zhidong Wang entered into the share transfer agreement on August 15, 2001
with each of Daniel Mao, Yuanchao Yan, Huai Lin, Jie Wang and Danhong Lin.
Pursuant to the said share transfer agreements, Zhidong Wang has transferred 30%
of the shares of the ICP Company to Daniel Mao and 10% of the shares of the ICP
Company to each of Yuanchao Yan, Huai Lin, Jie Wang and Danhong Lin.

E. A debt transfer and assumption agreement was entered into on August 15, 2001
among Zhidong Wang, Daniel Mao, Yuanchao Yan, Huai Lin, Jie Wang, Danhong Lin
and BSRS. Pursuant to the said debt transfer and assumption agreement, Zhidong
Wang has transferred his repayment obligation under the aforementioned loan
agreement with BSRS to Daniel Mao, Yuanchao Yan, Huai Lin, Jie Wang, and Danhong
Lin; Daniel Mao has assumed RMB300,000 loan obligation from Zhidong Wang and
each of Yuanchao Yan, Huai Lin, Jie Wang and Danhong Lin has assumed RMB100,000
loan obligation from Zhidong Wang.

F. As of the date of this Agreement, each of Daniel Mao and Yan Wang owns 30% of
the shares of the ICP Company and each of Yuanchao Yan, Huai Lin, Jie Wang and
Danhong Lin owns 10% of the shares of the ICP Company. To maintain their
interest in the ICP Company, each of Daniel Mao and Yan Wang owes BSRS
RMB300,000 and each of Yuanchao Yan, Huai Lin, Jie Wang and Danhong Lin owes
BSRS RMB100,000.

<PAGE>   2

Therefore, the parties agree to the following regarding the repayment of loan
from each of Daniel Mao, Yan Wang, Yuanchao Yan, Huai Lin, Jie Wang and Danhong
Lin to BSRS:

1.      Repayment of Loan

1.1     BSRS has the right to request each of Daniel Mao, Yan Wang, Yuanchao
        Yan, Huai Lin, Jie Wang and Danhong Lin (each hereinafter "the borrowing
        party") to transfer his/her interest in the ICP Company to BSRS or any
        person specified by BSRS at any time; provided that such transfer will
        not be in violation of PRC laws and regulations.

1.2     The borrowing party shall execute all necessary documents relating to
        the transfer of the interest in the ICP Company within three days
        following the receipt of the transfer request from BSRS and shall
        cooperate with the designated transferee to complete all the procedures
        relating to the transfer of the interest in the ICP Company.

1.3     Should the borrowing party transfer part of his/her interest in the ICP
        Company to BSRS or the person specified by BSRS under BSRS' request, the
        borrowing party shall be viewed as having repaid the amount of the loan
        as calculated in accordance with the following formula:
        X=T(multiplication symbol) (A degrees(division symbol)B). X means the
        amount of the loan deemed repaid, T means the total amount of the loan,
        A means the number of shares of the ICP Company being transferred to
        BSRS or the person specified by BSRS, and B means the total number of
        the shares of the ICP Company held by the borrowing party.

1.4     BSRS agrees that the borrowing party's fulfillment of the obligation to
        transfer his/her full interest in the ICP Company to BSRS or the person
        specified by BSRS shall be viewed as having repaid all of his/her loan.

1.5     Unless with the written consent of the borrowing party, BSRS shall not
        request the borrowing party to repay his/her loan in any form other than
        the transfer of the interest of the ICP Company.

1.6     Unless with the written consent of the BSRS, the borrowing party shall
        not transfer any of his/her interest in the ICP Company to any third
        party.

1.7     The parties, on the basis of equality, mutual benefit and both faith and
        through friendly negotiations, shall determine the method of the
        repayment if the borrowing party, under the PRC laws and regulations, is
        not able to transfer his/her interest in the ICP Company to BSRS or the
        person specified by BSRS.

2.      Effective and Miscellaneous

2.1     This Agreement goes into effect as of the date of signature by the
        parties.

2.2     Should there is any conflict between this Agreement and any other prior
        agreements or arrangements among the parties, the terms of this
        Agreement shall prevail.

2.3     This Agreement has seven original copies with equal legal force and each
        to be held by one party.

2.4     Matters uncovered by this Agreement may be separately discussed and
        decided by the parties.

<PAGE>   3

Daniel Mao                                  Yan Wang

/s/ Daniel Mao                              /s/ Yan Wang
-----------------------------------         ------------------------------------
(Signature)                                 (Signature)

Yuanchao Yan                                Huai Lin

/s/ Yuanchao Yan                            /s/ Huai Lin
-----------------------------------         ------------------------------------
(Signature)                                 (Signature)

Jie Wang                                    Danhong Lin

/s/ Jie Wang                                /s/ Danhong Lin
-----------------------------------         ------------------------------------
(Signature)                                 (Signature)

Beijing Stone Rich Sight Information Technology Co., Ltd

Authorized Representative Signature:  /s/ Yan Wang

* This Agreement is originally written in Chinese and this is an English
  translation.<PAGE>   1

                                                                     Exhibit 4.7

                                Fourth Amendment
                                     to the
                           Soligen Technologies, Inc.
                             1993 Stock Option Plan

        The following amendment to the Soligen Technologies, Inc. 1993 Stock
Option Plan, as amended (the "Plan"), was approved by the Shareholders of
Soligen Technologies, Inc. on August 24, 2001:

        1. The first sentence of Section 4.1 of the Plan shall be amended to
read as follows:

               "The Committee, from time to time, may provide for the option and
               sale in the aggregate of up to eight million shares of Common
               Stock, to be made available from authorized, but unissued, or
               reacquired shares of Common Stock."

                                        6<PAGE>   1

                                                                   EXHIBIT 10.47

June 14, 2001

Nagesh Palepu, Ph.D.
787 Niwot Ridge Lane
Lafayette, CO  80026

                         Re: Change In Control Agreement

Dear Nagesh:

        In consideration of your employment with Sonus Pharmaceuticals, a
Delaware corporation ("Sonus"), this letter agreement (the "Agreement") sets
forth the compensation and benefits you will be entitled to receive in the event
your employment terminates in connection with a change in control of the Company
under the conditions described below. This Agreement takes effect on the date
you commence employment with the Company.

1. TERMINATION OF EMPLOYMENT.

        1.1. During the term of this Agreement, you will be entitled to the
benefits provided in Section 2 of this Agreement in the event (A) a Change in
Control has occurred; and (B) (i) you terminate your employment with the Company
for Good Reason within 12 months following the Change of Control, or (ii) the
Company terminates your employment for reasons other than Cause, Disability, or
your death within 12 months following the Change of Control, provided you
fulfill your obligations under this Agreement.

        1.2 For purposes of this Agreement, the term "Change in Control" shall
mean (i) a sale of fifty percent (50%) or more of the outstanding shares of
common stock of the Company; (ii) a sale of all or substantially all of the
assets of the Company, or (iii) a merger, consolidation or reorganization
whereby the stockholders of the Company immediately prior to the consummation of
such merger, consolidation or reorganization own less than fifty percent (50%)
of the outstanding shares of common stock immediately following the consummation
of the merger, consolidation or reorganization.

        1.3. For purposes of this Agreement, the term "Good Reason" shall mean
any of the following, if done without your consent:

                1.3.1. A substantial diminution in your duties and
responsibilities to a level substantially beneath that of your duties and
responsibilities at the outset of your employment under this Agreement other
than actions that are not taken in bad faith and are remedied by the Company
within thirty days after written notice by you;

<PAGE>   2

                1.3.2. A reduction by the Company in your current annual base
salary unless such reduction is attributable to an across the board salary
reduction for all of management personnel of the Company and then only if the
percentage of your reduction is (i) not greater than 20%, and (ii) no greater
than that of the other management personnel;

                1.3.3. The Company requires the relocation of your base of
employment outside the Seattle, Washington metropolitan area;

                1.3.4. A material breach by the Company of any of the terms and
provisions of this Agreement, which is not cured within 30 days of written
notice by you of such breach; or

                1.3.5. The failure of the Company to obtain a satisfactory
agreement from any successor in a Change of Control to assume and agree to
perform this Agreement, as contemplated in Section 6 hereof.

        1.4 For purposes of this Agreement, the term "Cause" shall mean any of
the following: (i) your willful and continued failure or refusal to perform your
duties with the Company; (b) your willfully engaging in gross misconduct
injurious to the Company; (c) your being convicted or pleading guilty or nolo
contendere to any misdemeanor involving moral turpitude or to any felony; (d)
your having materially breached any provision of this Agreement, or any
agreement concerning confidentiality or ownership of inventions with the Company
and failed to cure such breach to the reasonable satisfaction of the Company
promptly after receiving written notice of breach if such cure is possible.

        1.5. For purposes of this Agreement, the term "Disability" shall mean
your inability to perform the essential functions of your position due to any
physical or mental illness even with reasonable accommodation to the extent
required by law, for any period of six months in the aggregate during any twelve
months, provided the Company has given you a written demand to return to your
fill time duties.

        1.6 Any termination of employment by you or by the Company pursuant to
this Agreement shall be communicated by written Notice of Termination indicating
the termination provision in this Agreement relied upon, if any. For purposes of
this Agreement, the "Date of Termination" shall mean the date specified in the
Notice of Termination which shall not be earlier than ten (10) business days
after the date on the Notice of Termination is given.

2. COMPENSATION UPON TERMINATION.

        2.1. If your employment shall be terminated and you are entitled to
benefits under Section 1 of this Agreement then, except as provided in
Subsection 2.2, you shall receive the following benefits:

                2.1.1. the Company shall pay to you in a lump sum within ten
days following the Date of Termination (a) your base salary unpaid through the
Date of Termination at the rate in effect as of the time of Notice of
Termination and (b) an amount equal to the value as of the Date

                                       2
<PAGE>   3

of Termination of the deferred portion of any bonus which has been declared but
is unpaid under any incentive compensation plan or program of the Company then
in effect;

                2.1.2. the Company shall pay to you as severance pay in a lump
sum within thirty days following the Date of Termination an amount equal to your
highest annual base salary in effect any time during the twelve (12) month
period prior to the Date of Termination; and

                2.1.3. the Company shall maintain in full force and effect, for
the continued benefit of you for one year after the Date of Termination, or, if
sooner, until you are employed in a full-time capacity by another employer, all
non-cash health and welfare plans and programs (excluding 401(k) or any employee
bonus plans and programs or retirement plans or programs) in which you
participated immediately prior to the Date of Termination provided that your
continued participation is permissible under the general terms and provisions of
such plans and programs. In the event that your participation in any such plan
or program is barred, the Company shall arrange to provide you with benefits
substantially similar to those which you are entitled to receive under such
plans and programs at no cost to you. At the end of the period of coverage, you
shall have the option to have assigned to you at no cost and with no
apportionment of prepaid premiums, any assignable insurance policy owned by the
Company and relating to specifically to you.

        2.2. Notwithstanding Section 1, the respective obligations of, and
benefits afforded to, the Company and you as provided in this Section 2, shall
survive termination of this Agreement.

        2.3. No compensation or benefits shall be due under this Agreement in
the event your employment is terminated by you or the Company in circumstances
other than those described in Section 1.1, including but not limited to a
termination by you for any reason other than Good Reason, a termination by the
Company for Cause, disability, or death, or any termination that does not occur
within twelve months following a Change in Control.

        2.4. To the extent that any or all of the payments and benefits provided
for in this Agreement constitute "parachute payments" within the meaning of
Section 280G of the Internal Revenue Code (the "Code") and, but for this Section
2.4 would be subject to the excise tax imposed by Section 4999 of the Code, the
aggregate amount of such payments and benefits shall be reduced such that the
present value thereof (as determined under the Code and applicable regulations)
is equal to 2.99 times the Executive's "base amount" (as defined in the Code).
The determination of any reduction of any payment or benefits under Section 2
pursuant to the foregoing provision shall be made by a nationally recognized
public accounting firm chosen by the Company in good faith, and such
determination shall be conclusive and binding on the Company and you.

3. OTHER BENEFITS.

        In the event you are entitled to any compensation or benefits under this
Agreement, you shall not be entitled to any other severance compensation or
benefits under any other policy or agreement with the Company.

                                       3
<PAGE>   4

4. PROPRIETARY INFORMATION AND UNFAIR COMPETITION.

        4.1 You acknowledge that in the course of your employment with the
Company, you will be entrusted with access to extensive confidential information
of the Company concerning its products and service, methods of manufacture,
research and development, know-how, patents, copyrights, trademarks, and other
proprietary data, as well as the identity, needs, and preferences of its
customers and prospects, all of which the Company considers its legally
protected trade secrets and intellectual property. You further acknowledge the
highly competitive nature of the business of the Company, and the fact that
unauthorized disclosure or use of such trade secrets and intellectual property
would be inevitable if you were to compete with the Company or solicit competing
business from its prospects and customers. You therefore agree as follows:

        4.2 Commencing on the Date of Termination, and ending one year
thereafter (the "Non-Compete Period"), you will not provide goods or services to
or become an employee, owner (except for passive investments of not more than
three percent of the outstanding shares of, or any other equity interest in, any
company or entity listed or traded on a national securities exchange or in an
over-the-counter securities market), officer, agent, consultant, advisor or
director of any firm or person in any geographic area which competes in the
"Business". For purposes of this Agreement, the term "Business" shall mean the
research, design, development, manufacture, sale or distribution of (i) drug
delivery products using Vitamin E technology, or (ii) blood substitute products
using fluorocarbon technology.

        4.3 During the Non-Compete Period, you will not directly or indirectly
induce any employee of the Company or any of its affiliates to engage in any
activity in which you are prohibited from engaging by paragraph 4.1 above, or to
terminate such employee's employment with the Company, or any of its affiliates,
and will not directly or indirectly employ or offer employment to any person who
was employed by the Company or any of its affiliates unless such person shall
cease to be employed by the Company or any of its affiliates for a period of at
least 12 months; provided, however, that this provision shall not apply to any
person who is no longer an employee of the Company or any of its affiliates as
of a result of actions taken by the Company or its affiliates.

        4.4 During the Non-Compete Period, you will refrain from making any
statement which has the effect of demeaning the name or the business reputation
of the Company or its subsidiaries or affiliates, or any officer or employee
thereof, or which materially adversely effects the best interests (economic or
otherwise) of the Company, its subsidiaries or affiliates.

        4.5. It is expressly understood and agreed that although you and the
Company consider the restrictions contained in this Section 4 to be reasonable,
if a final judicial determination is made by a court of jurisdiction that the
time or territory or any other restriction contained in this Agreement is an
unenforceable restriction against you, provisions of this Agreement shall not be
rendered void, but shall be deemed amended to apply to such maximum time and
territory and to such maximum extent as such court may judicially determine or
indicate to be enforceable. Alternatively, if any court of competent
jurisdiction finds that any restriction contained in this Agreement is
unenforceable, and such restriction cannot be amended so as to make it

                                       4
<PAGE>   5

enforceable, such finding shall not effect the enforceability of any of the
other restriction contained herein.

5. MISCELLANEOUS.

        Any payment required under this Agreement shall be subject to all
requirements of the law with regard to withholding, filing, making of reports
and the like, and the Company shall use its commercially reasonable best efforts
to satisfy promptly all such requirements. No provisions of this Agreement may
be modified, waived or discharged unless such waiver, modification or discharge
is agreed to in writing signed by both parties. The validity, interpretation,
construction and performance of this Agreement shall be governed by the law of
the State of Delaware.

6. SUCCESSORS AND ASSIGNMENT.

        This agreement and all of your rights thereunder shall inure to the
benefit of and be enforceable by your personal or legal representatives,
executors, administrators, successors, heirs, distributees, devisees and
legatees. Except as expressly provided in this Agreement, this Agreement is
personal to you and may not be assigned to you. If you should die while any
amounts would still be payable to you hereunder if you had continued to live,
all such amounts, unless otherwise provided herein, shall be paid in accordance
with the terms of this Agreement to your devisee, legatee, or other designee or,
if there be no such designee, to your estate. This Agreement shall be binding
upon any successor to the Company (whether direct or indirect, by purchase,
merger, consolidation or otherwise) to all or substantially all of the business
and/or assets of the Company.

7. TERM OF AGREEMENT.

        This Agreement shall commence as of the date of this Agreement and shall
terminate on the earliest of (i) three (3) years from the date of this
Agreement, (ii) the termination of your employment by the Company for Cause,
Disability or death; (iii) your termination of employment other than for Good
Reason or (iv) your reaching age 65.

8. NO GUARANTEE OF CONTINUED EMPLOYMENT.

        This Agreement is intended solely to provide you with certain
compensation and benefits in the event your employment terminates in the
circumstances described in Section 1.1. Nothing in this Agreement constitutes or
implies any specific term of employment. You acknowledge and agree that your
employment with the Company can be terminated by you or the Company at any time
with or without cause or prior warning. Nothing in this Agreement limits or
supercedes any other agreements between you and the Company concerning
confidentiality or ownership of intellectual property.

9. MEDIATION

                                       5
<PAGE>   6

        In the event that the Company terminates you for Cause and you dispute
its right to do so or you claim that your are entitled to terminate your
employment for Good Reason and the Company disputes your right to do so, a
mediator acceptable to you and the Company will be appointed within ten (10)
days to assist in reaching a mutually satisfactory resolution but will have no
authority to issue a binding decision. Such mediation must be concluded within
60 days of the date of termination or claim to termination. Should such
mediation fail to reach an acceptable conclusion and you are successful in any
litigation or settlement that issues from such dispute, you shall be entitled to
receive from the Company all of the expenses incurred by you in connection with
any such dispute including reasonable attorney's fees.

        If this Agreement is acceptable to you, kindly sign and return to the
Company the enclosed copy of this letter.

                                       Sincerely,

                                       Sonus Pharmaceuticals, Inc.

                                       /s/ Michael A. Martino
                                       -----------------------------------------
                                       Michael A. Martino
                                       President and C.E.O.

AGREED AND ACCEPTED:

/s/ Nagesh Palepu
----------------------------------
Nagesh Palepu

Dated: June 26, 2001

                                       6

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00030-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00030-of-00352.parquet"}], [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00030-of-00352.parquet"}]]