...B¹

Corresponding author: Tel: 301-975-5865; Fax: 301-990-6891; E-mail: dale.bentz@nist.gov.

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... Lego²

Certain commercial equipment is identified in this paper to specify the experimental procedure. In no case does such identification imply endorsement by the National Institute of Standards and Technology, nor does it indicate that the products are necessarily the best available for the purpose.

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