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Chemistry

Chemical engineering and processing

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Displaying 251 - 275 of 407

Effect of Dissolved Nitrogen Gas on the Density of Di-2-Ethylhexyl Sebacate: Working Fluid of the NIST Oil Ultrasonic Interferometer Manometer Pressure Standard

June 1, 2009
Author(s)
Jay H. Hendricks, Jacob R. Ricker, Justin H. Chow, Douglas A. Olson
The National Institute of Standards and Technology (NIST) Low Pressure Manometry Laboratory maintains national pressure standards ranging from 1 mPa to 360 kPa through the operation of four ultrasonic interferometer manometer (UIM) pressure standards. NIST

On the determination of C0 (or A0), D0K, H0K, and some dark states for symmetric-top molecules from infrared spectra without the need for localized perturbations

May 4, 2009
Author(s)
Alfons Weber, Jintao Zhang, Tony Masiello, Thomas A. Blake, J Nibler
For symmetric top molecules, the normal k = 0, l = 0 and k = 1, l = 1 selection rules for parallel and perpendicular bands, respectively, do not allow the determination of the K-dependent rotational constants, C0 (or A0), D0K, and H0K. However, we

Report on Acceleration Comparison SIM.AUV.V-K1 - Draft B

March 20, 2009
Author(s)
David J. Evans, Adriana Hornikova, Stefan D. Leigh, Andrew L. Rukhin, William E. Strawderman
The first regional key comparison in vibration conducted under the auspices of the Inter-American System of Metrology (SIM) was begun in 1996. The comparison was registered with the International Bureau of Weights and Measures (BIPM) through the

Advice from the CCL on the use of unstabilized lasers as standards of wavelength: the helium-neon laser at 633 nm

January 1, 2009
Author(s)
Jack A. Stone Jr., Jennifer Decker, Patrick Gill, Andrew Lewis, Patrick Juncar, Daniele Rovera, Miguel Villiseid
The Consultative Committee for Length has recommended that red (633 nm) unstabilized Helium-Neon lasers, operating on the 3s2¿_2p4 transition, should be included in the list of standard frequencies for realization of the meter. This article discusses

Droplet Formation at Microfluidic T-junctions

December 31, 2008
Author(s)
David A. LaVan, Xiang Xu
Analysis of droplet formation in microfluidic systems is important to understand the operation of these devices, and to permit optimal design and process control. Droplet formation in microfluidic T-junction devices was studied using experimental and

Design and testing of a software feedback loop for RF power leveling

December 12, 2008
Author(s)
Xiaohai Cui, Thomas P. Crowley
We have developed a software feedback loop that stabilizes the RF power input in calorimetric measurements to better than 30 ppm. In this system, a bolometric sensor with a Type IV power meter is used to detect the power. Feedback is provided to the AM

Multichannel Decomposition and Isomerization of Octyl Radicals

October 9, 2008
Author(s)
Wing Tsang, William S. McGivern, Jeffrey A. Manion
The thermal cracking patterns from the decomposition and isomerization of octyl-1 radicals have been determined from the pyrolysis of n-octyl iodide in single pulse shock tube experiments at temperatures in the 850-1000 K range and pressures near 2 bar

NIST Microform Calibration System for Rockwell Hardness Standardization

August 25, 2008
Author(s)
Jun-Feng Song, Samuel R. Low III, Xiaoyu A. Zheng
In the uncertainty budget of Rockwell hardness tests, microform geometric errors of the diamond indenter are a major contributor. The microform calibration of Rockwell diamond indenters has been one of the key steps for Rockwell hardness standardization

Measuring the Phase Transfer Function of a Phase-Shifting Interferometer

August 13, 2008
Author(s)
JiYoung Chu, Quandou (. Wang, John P. Lehan, Ulf Griesmann, Guangjun Gao
In characterizing the performance of a phase-shifting interferometer, the dependence of the measured height on the spatial frequency is rarely considered. We describe a test mirror with a special height relief that can be used to measure the height

Natural Gas Flow Calibration Service

August 1, 2008
Author(s)
Aaron Johnson
This document describes NIST's high pressure natural gas flow calibration service (NGFCS). Flow calibrations are conducted offsite at the Colorado Experimental Engineering Station Incorporated (CEESI) in Garner, Iowa. A parallel array of nine turbine meter

Stationary and non-stationary deformations in three-flat tests

July 7, 2008
Author(s)
Ulf Griesmann, Quandou (. Wang, Nicolas Laurenchet, Johannes A. Soons
Calibration procedures for optical reference flats of phase-shifting interferometers (three-flat tests) are critically important if flatness measurements with low uncertainty are desired. In these tests, all combinations of three flats with unknown

Calculated Performance of Low-Porosity Regenerators at 4 K with He-4 and He-3

June 9, 2008
Author(s)
Ray Radebaugh, Yonghua Huang, Agnes A. O'Gallagher, John M. Gary
Previously we have shown that the lower volumetric heat capacity and more ideal behavior of helium-3 compared with helium-4 at 4 K results in an improved performance for packed sphere regenerators operating with helium-3 between 4 K and about 20 K. In this

A New Microdevice for SI-Traceable Forces in Atomic Force Microscopy

June 2, 2008
Author(s)
Gregory W. Vogl, Jason J. Gorman, Gordon A. Shaw, Jon R. Pratt
A new self-excited micro-oscillator is proposed as a velocity standard for dissemination of nanoNewton-level forces that are traceable to the International System of Units (SI). The microfabricated oscillator is top-coated with magnetic thin films and
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