Exhibit 10.1

AMENDMENT OF LEASE

THIS AGREEMENT, made as of the first day of April, 2012, by and between KBS
RIVERTECH, LLC, a Delaware limited liability company, as successor-in-interest
to Nortel Networks HPOCS Inc. (hereinafter referred to as “Landlord”), and
ENTEGRIS, INC., a Delaware corporation, as successor-in-interest to Mykrolis
Corporation (hereinafter referred to as “Tenant”)

W I T N E S S E T H   T H A T:

WHEREAS, Landlord and Tenant are parties to an existing lease agreement dated
April 1, 2002 (hereinafter referred to as the “Lease”) relating to certain
Premises comprising Building 2 of RiverTech Park, located at 129 Concord Road,
Billerica, Massachusetts, all as more particularly described and set forth in
the Lease; and

WHEREAS, the term of the Lease is scheduled to expire on March 31, 2014; and

WHEREAS, Landlord and Tenant wish to extend said term, subject to the provisions
hereof;

NOW THEREFORE, in consideration of the foregoing recitals and for further good
and valuable consideration, the receipt and adequacy whereof are hereby
acknowledged, Landlord and Tenant do hereby agree as follows:

1. The term of the Lease is hereby extended through the close of the 31st day of
March, 2019. Except as otherwise hereinafter set forth, said extension shall be
subject to all terms, conditions and other provisions contained in the Lease.

2. Commencing as of April 1, 2012, Tenant will pay Fixed Rent to Landlord
pursuant to Section 5 of the Lease in accordance with the following schedule:

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With respect to the

following period:

   Fixed Rent per
annum shall  be:      Monthly installments
of fixed  Rent shall be:  

April 1, 2012 - March 31, 2014

   $  2,188,600.08       $  182,383.34   

April 1, 2014 - March 31, 2016

   $ 2,398,220.28       $ 199,851.69   

April 1, 2016 - March 31, 2018

   $ 2,534,145.00       $ 211,178.75   

April 1, 2018 - March 31, 2019

   $ 2,670,069.84       $ 222,505.82   

Notwithstanding the foregoing, no installments of fixed Rent shall be due or
payable pursuant to Section 5 of the Lease with respect to the period commencing
on April 1, 2014 and ending on July 31, 2014.

3. Tenant accepts the Premises for continuing occupancy in their existing
condition and state of repair “as is” on the date hereof, and Landlord shall
have no obligation to make any improvements of any kind thereto or contribute to
the cost thereof.

4. Notwithstanding any other provision of the Lease to the contrary, Tenant
shall, from and after the date hereof and within thirty (30) days following
billing, reimburse 50% of any costs incurred by Landlord in order to remove snow
and ice from the roof of the Premises whenever required in Landlord’s reasonable
opinion, based on a concern that the weight of any existing snow and ice
together with anticipated additional accumulations may threaten to exceed the
load bearing capacity of such roof, for the purpose of preventing damage to such
roof.

5. Following execution hereof, the amount of the letter of credit held by
Landlord pursuant to Section 6 of the Lease may be reduced to $100,000.00 and
Landlord shall agree to an appropriate amendment of such letter of credit in
order to effect such reduction.

6. Landlord represents and warrants that the only mortgage presently encumbering
the Premises is held by Wells Fargo Bank, National Association, as
administrative agent for itself and certain additional parties pursuant to an
instrument dated February 20, 2008 and recorded with the Middlesex Northern
District Registry of Deeds at Book 21958, Page 1.

 

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7. Tenant shall retain its option pursuant to Section 28 of the Lease to further
extend the term thereof except that (a) such option shall be limited to a single
four (4) year extension period beginning on April 1, 2019, (b) Tenant’s notice
exercising such option shall be given on or before March 31, 2018 and (c) any
reference in said Section to the Fair Market Rate shall be deemed to refer to
95% of such Rate.

8. For purposes of Section 43 of the Lease, the term “Broker” as used with
respect to the transactions described herein shall be defined to mean Richards
Barry Joyce & Partners LLC and Jones Lang LaSalle Americas Inc., whose
commission shall in each case be the responsibility of Landlord pursuant to a
separate agreement.

9. Unless the context requires otherwise, the terms used herein shall be
construed in conformity with the definitions set forth in the Lease.

10. Except as herein modified, the Lease is hereby ratified and confirmed.

 

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IN WITNESS WHEREOF, Landlord and Tenant have caused this instrument to be
executed under seal as of the day and year first above written.

KBS RIVERTECH, LLC

 

By   KBS REIT Acquisition XXXI, LLC   its sole member   By   KBS REIT
Properties, LLC     its sole member     By   KBS Limited Partnership       its
sole member       By   KBS Real Estate Investment Trust, Inc.         its
general partner         By       /s/ Randi Kaufman         Its       Senior Vice
President               title (duly-authorized)

 

ENTEGRIS, INC. By       /s/ Peter W. Walcott Its       Senior Vice President &
General Counsel       title (duly-authorized)

 

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