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                                                                    EXHIBIT 4.16
                                  Proliq, Inc.

                       Incorporated Under the Laws of the

                               State of New Jersey

                                RESTATED BY-LAWS


                                    ARTICLE I
                                     OFFICES

                  The principal office of the Corporation shall be located in
the State of Texas. The Board of Directors may change the location of the
principal office of the Corporation and may from time to time designate other
offices at such other places, either within or without the State of New Jersey,
as the business of the Corporation may require.

                                   ARTICLE II
                                  STOCKHOLDERS

                  Section 1. Annual Meeting: The Annual Meeting of Stockholders
for the election of Directors and the transaction of any other business as may
properly come before such meeting shall be held on such day, at such time and at
such place as shall be designated by the Board of Directors. If said day be a
legal holiday, said meeting shall be held at the same hour on the next
succeeding business day. At the Annual Meeting any business may be transacted
and any corporate action may be taken, whether stated in the notice of meeting
or not, except as otherwise expressly provided by statute or the Certificate of
Incorporation.

                  Section 2. Special Meetings: Special Meetings of the
Stockholders for any purpose may be called as provided in the Certificate of
Incorporation. Special Meetings shall be held at such time and place as shall
from time to time be designated by the Board of Directors and stated in the
notice of such meeting. At a Special Meeting no business shall be transacted and
no corporate action shall be taken other than that stated in the notice of the
meeting.

                  Section 3. Notice of Meetings: Written notice of the place,
date and hour of any Stockholders' meeting, whether annual or special, and, in
the case of a special meeting, the purpose or purposes for which the meeting is
called shall be given to each


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Stockholder entitled to vote thereat, by mailing the same to him at his address
as the same appears upon the records of the Corporation not less than ten (10)
nor more than sixty (60) days prior to the date of such meeting. Notice of any
adjourned meeting need not be given other than by announcement at the meeting so
adjourned, unless otherwise ordered in connection with such adjournment. Such
further notice, if any, shall be given as may be required by law.

                  Section 4. Waiver of Notice: A written waiver of notice signed
by the person entitled to notice, whether before or after the meeting, shall be
deemed equivalent to notice. Attendance of a Stockholder at a meeting shall
constitute a waiver of notice of such meeting, except when a Stockholder attends
a meeting for the express purpose of objecting, at the beginning of the meeting,
to the transaction of any business on the grounds that the meeting shall not
have been lawfully called or convened.

                  Section 5. Quorum: Any number of Stockholders, together
holding at least a majority of the capital stock of the Corporation issued and
outstanding and entitled to vote, present in person or represented by proxy at
any meeting duly called, shall constitute a quorum for all purposes at a meeting
of Stockholders except as may otherwise be provided by law.

                  Section 6. Adjournment of Meetings: If at the time for which a
meeting of Stockholders has been called less than a quorum is present, the
meeting may be adjourned to another time or place by a majority vote of the
Stockholders present in person or represented by proxy and entitled to vote
thereat, without notice other than by announcement at the meeting except as may
otherwise be required by law. At any adjourned meeting at which a quorum shall
be present, any business may be transacted which might have been transacted at
the meeting as originally called.

                  Section 7. Voting: Each Stockholder entitled to vote at a
meeting of the Stockholders shall be entitled to one vote for each share of
stock registered in his name on the books of the Corporation on the date fixed
as a record date for the determination of its Stockholders entitled to vote.
Each Stockholder entitled to vote at a meeting of Stockholders may authorize
another person or persons to act for him by proxy, duly appointed by instrument
in writing subscribed by such Stockholder and bearing a date not more than three
years prior to said meeting, unless said proxy provides for a longer period. At
all meetings of Stockholders all matters shall be determined by a majority vote
of the Stockholders entitled to vote thereat present in person or represented by
proxy except as otherwise provided by law, the Certificate of Incorporation or
these By-Laws.


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                                   ARTICLE III
                                    DIRECTORS

                  Section 1. Qualifications: Directors need not be stockholders.

                  Section 2. Duties and Powers: The Board of Directors shall
have control and management of the affairs and business of the Corporation, and,
unless the vote of a greater number is required by law, the Certificate of
Incorporation or these By-Laws, the vote of the majority of the Directors
present at a meeting shall be the act of the Board of Directors in the
transaction of business, provided a quorum is present. The Directors may
exercise all such powers of the Corporation and do all such lawful acts and
things as they may deem proper and as are consistent with law, the Certificate
of Incorporation and these By-Laws.

                  Section 3. Election and Term: Directors shall be elected by
the stockholders at the Annual Meeting of Stockholders to hold office until the
next Annual Meeting of Stockholders and until their successors are elected and
qualified or until their earlier resignation or removal. If the election of
directors shall not be held on the day designated by or pursuant to authority
granted in these By-Laws, the Directors shall cause the same to be held as soon
thereafter as may be convenient. The Board of Directors shall consist of not
less than two (2) persons. The number of directors may be changed from time to
time, within the limitations stated in the immediately preceding sentence,
exclusively by the Board of Directors pursuant to a resolution adopted by a
majority of the total number of authorized directors (whether or not there
exists any vacancies in previously authorized directorships at the time any such
resolution is presented to the Board for adoption.) The election of directors
need not be by ballot. Except as may otherwise be provided by the General
Corporation Law, any director or the entire board of directors may be removed,
with or without cause, by the holders of a majority of the shares then entitled
to vote at an election of directors.

                  Section 4. Resignation of Directors: Any Director may resign
at any time upon written notice to the Corporation. Such resignation shall take
effect at the time specified therein, and if no time be specified, at the time
of its receipt by the Chairman of the Board, if any, the President or the
Secretary. The acceptance of a resignation shall not be necessary to make it
effective, unless so specified therein.

                  Section 5. Meetings: The Board of Directors shall hold an
annual meeting for the purpose of organization and the transaction of any
business immediately after the Annual Meeting of the Stockholders, provided a
quorum is present. Other regular meetings may be held at such times as may be
determined from time to time by resolution



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of the Board of Directors. Special meetings of the Board of Directors may be
called at any time by the Chairman of the Board, if any, or by the President.

                  Section 6. Notice and Place of Meetings: Regular meetings of
the Board of Directors may be held at such time and place as shall be designated
by resolution of the Board of Directors. No notice need be given of any regular
meeting of the Board. Notice of any special meeting specifying the time and
place of such meeting and the business to be transacted thereat shall be served
upon each Director by mail at his residence or usual place of business at least
two (2) days before the day on which such meeting is to be held, or sent to him
at such place by telegraph or cable, or transmitted by way of a guaranteed
overnight courier service, or delivered personally or by telephone not later
than 24 hours prior to the time at which the meeting is to be held. No notice of
the annual meeting shall be required if held immediately after the annual
meeting of the Stockholders and if a quorum is present. Notice of a meeting need
not be given to any Director who submits a signed waiver of notice before or
after the meeting, nor to any Director who attends the meeting without
protesting prior thereto or at its commencement the lack of notice.

                  Section 7. Business Transacted at Meetings: Any business may
be transacted and any corporate action may be taken at any regular or special
meeting of the Board of Directors at which a quorum shall be present, whether
such business or proposed action be stated in the notice of such meeting or not,
unless special notice of such business or proposed action shall be required by
law.

                  Section 8. Quorum: A majority of the entire Board of Directors
shall be necessary to constitute a quorum for the transaction of business. If a
quorum is not present at a meeting of the Board of Directors, a majority of the
Directors present may adjourn the meeting to such time and place as they may
determine without notice other than announcement at the meeting until enough
Directors to constitute a quorum shall attend. When a quorum is once present to
organize a meeting, it shall not be broken by the subsequent withdrawal of any
Directors.

                  Section 9. Action Without a Meeting: Any action required or
permitted to be taken at any meeting of the Board of Directors or any committee
thereof may be taken without a meeting if all members of the Board or such
committee, as the case may be, consent in writing to the adoption of a
resolution authorizing the action. Such resolutions and the written consents
thereto by the members of the Board or a committee shall be filed with the
minutes of the proceedings of the Board or such committee as the case may be.


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                  Section 10. Participation By Telephone: Any one or more
members of the Board or any committee thereof may participate in a meeting of
the Board or such committee by means of a conference telephone or similar
communications equipment by means of which all persons participating in the
meeting can hear each other at the same time. Participation by such means shall
constitute presence in person at a meeting.

                  Section 11. Compensation: The Board of Directors may establish
by resolution reasonable compensation of all Directors for services to the
Corporation as Directors, including a fixed fee and expenses, if any, incurred
in attending each meeting. Nothing herein contained shall preclude any Director
from serving the Corporation in any other capacity, as an officer, agent or
otherwise, and receiving compensation therefor.

                                   ARTICLE IV
                                    OFFICERS

                  Section 1. Number: The officers of the Corporation shall be a
President, Secretary and such Vice-Presidents and other officers as the
Board may deem advisable. The Board of Directors, in its discretion, may also
elect a Chairman of the Board of Directors.

                  Section 2. Election, Term of Office and Qualifications: The
officers shall be elected annually by the Board of Directors immediately after
the Annual Meeting of stockholders and shall serve at the pleasure of the Board.
Any two or more offices may be held by the same person, except the offices of
the President and Secretary.

                  Section 3. Removal of Officers: Any officer of the Corporation
may be removed from office, with or without cause, by a vote of a majority of
the Board of Directors.

                  Section 4. Resignation: Any officer of the Corporation may
resign at any time. Such resignation shall be in writing and shall take effect
at the time specified therein, and if no time be specified, at the time of its
receipt by the Secretary. The acceptance of a resignation shall not be necessary
in order to make it effective, unless so specified therein.

                  Section 5. Filling of Vacancies: A vacancy in any office shall
be filled by the Board of Directors.

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                  Section 6. Compensation: The compensation of the Officers
shall be fixed by the Board of Directors, or by any committee or Officer upon
whom power in that regard may be conferred by the Board of Directors.

                  Section 7. President: The President shall have responsibility
for the general direction of the business affairs and property of the
Corporation, and of its several Officers, and shall have and exercise all such
powers and discharge such duties as usually pertain to the office of President.
He shall perform such duties as may be assigned to him from time to time by the
Board of Directors. In the absence of the Chairman of the Board, the President
shall perform and carry out the functions of the Chairman of the Board.

                  Section 8. Vice-Presidents: During any absence or incapacity
of the President, the officers in the following order shall perform the duties
and exercise the powers of the President, and shall perform such duties and
functions as the Board may prescribe: (a) the Vice-President (or if there shall
be more than one, the Vice-Presidents in the order determined by the Board of
Directors); (b) the Assistant Vice-President (or if there shall be more than
one, the Assistant Vice-Presidents in the order determined by the Board of
Directors). Each Vice-President shall perform such other duties as may be
assigned to him by the President or the Board of Directors.

                  Section 9. Secretary: The Secretary shall attend all meetings
of the Board of Directors and of the Stockholders and record all votes and the
minutes of all proceedings in a book to be kept for that purpose. He shall give
or cause to be given notice of all meetings of stockholders and special meetings
of the Board of Directors and shall perform such other duties as may be
prescribed by the Board of Directors. He shall keep in safe custody the seal of
the Corporation and affix it to any instrument when so authorized by the Board
of Directors. In the absence of a Secretary, an Assistant Secretary may act in
his place.

                                    ARTICLE V
                                  CAPITAL STOCK

                  Section 1. Issue of Certificates of Stock: Certificates of
capital stock shall be in such form as shall be approved by the Board of
Directors.

                  Section 2. Registration and Transfer of Shares: The name of
each person owning a share of the capital stock of the Corporation shall be
entered on the books of the Corporation together with the number of shares held
by him, the numbers of the certificates covering such shares and the dates of
issue of such certificates. The shares of



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stock of the Corporation shall be transferable on the books of the Corporation
by the holders thereof in person, or by their duly authorized attorneys or legal
representatives, on surrender and cancellation of certificates for a like number
of shares, accompanied by an assignment of power of transfer endorsed thereon or
attached thereto, duly executed, and with such proof of the authenticity of the
signature as the Corporation or its Agents may reasonably require. A record
shall be made of each transfer.

                  The Board of Directors may make other and further rules and
regulations concerning the transfer and registration of certificates of stock.

                  Section 3. Lost, Destroyed and Mutilated Certificates: The
holder of any stock of the Corporation shall immediately notify the Corporation
of any loss, theft, destruction or mutilation of the certificates thereof. The
Corporation may issue a new certificate of stock in the place of any certificate
theretofore issued by it alleged to have been lost, stolen or destroyed, and the
Board of Directors may, in its discretion, require the owner of the lost, stolen
or destroyed certificate, or his legal representatives, to give the Corporation
a bond, in such sum not exceeding double the value of the stock and with such
surety or sureties as they may require, to indemnify it against any claim that
may be made against it by reason of the issue of such new certificate and
against all other liability in the premises, or may remit such owner to such
remedy or remedies as he may have under the laws of the State of New Jersey.

                                   ARTICLE VI
                            MISCELLANEOUS PROVISIONS

                  Section 1. Fiscal Year: The fiscal year of the Corporation
shall commence on the first day of January and end on the last day of December.

                  Section 2. Corporate Seal: The corporate seal shall be in such
form as approved by the Board of Directors and may be altered at their pleasure.
The corporate seal may be used by causing it or a facsimile thereof to be
impressed, affixed or otherwise reproduced.

                  Section 3. Notices: Except as otherwise expressly provided,
any notice required by these By-Laws to be given shall be sufficient if given by
depositing the same in a post office or letter box in a sealed wrapper with
first-class postage prepaid thereon and addressed to the person entitled thereto
at his address, as the same appears upon the books of the Corporation, or by
telegraphing or cabling the same to such person at such address or by
transmitting the same by way of a guaranteed overnight courier service; and



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such notice shall be deemed to be given at the time it is mailed, telegraphed,
cabled or so transmitted.

                                   ARTICLE VII
                                   AMENDMENTS

                  These Restated By-Laws may be amended or repealed, or new
By-Laws may be adopted, at any annual or special meeting of the Stockholders, by
vote of the Stockholders entitled to vote in the election of Directors;
provided, however, that the notice of such meetings shall have been given as
provided in these By-Laws, which notice shall state that amendment or repeal of
these By-Laws, or the adoption of new By-Laws, is one of the purposes of such a
meeting; and provided further, that By-Laws adopted by the Stockholders shall
not be rescinded, altered, amended or repealed by the Board of Directors if such
By-Laws adopted by the Stockholders so express. These Restated By-Laws may also
be amended or repealed, or new By-Laws may be adopted, by the Board of Directors
at any meeting thereof; provided, however, that notice of such meeting shall
have been given as provided in these By-Laws, which notice shall state that
amendment or repeal of the By-Laws, or the adoption of new By-Laws, is one of
the purposes of such meeting; and provided further, that By-Laws adopted by the
Board of Directors may be amended or repealed by the Stockholders as hereinabove
provided.

Dated:  February 20, 2001



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