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Chemistry

Chemical engineering and processing

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Displaying 226 - 250 of 405

Monitoring and Controlling Oxygen Levels in Microfluidic Devices

April 30, 2010
Author(s)
Samuel Forry, Peter C. Thomas, Srinivasa R. Raghavan
Mammalian cell culture has been traditionally performed in a static oxygen concentration of 20 mol %. However, oxygen level in vivo is significantly more hypoxic with an average oxygen concentration of 3 mol % to 5 mol %. In addition, many cells within the

Mixed Refrigerants for a Glass Capillary Micro Cryogenic Cooler

April 24, 2010
Author(s)
Mu Hong Lin, Peter E. Bradley, Marcia L. Huber, Ryan J. Lewis, Ray Radebaugh, Yung-Cheng Lee
Optimized mixed refrigerants are applied in Joule-Thomson (JT) micro cryogenic coolers (MCC) to enhance efficiency. Mixed refrigerants deliver equivalent refrigeration power with much lower pressure ratio and flow rate compared to pure nitrogen refrigerant

Kinetics of the Thermal Reaction of H Atoms with Propyne

April 15, 2010
Author(s)
Claudette M. Rosado-Reyes, Jeffrey A. Manion, Wing Tsang
The reaction of hydrogen atoms with propyne(CH≡CCH3) has been investigated in a heated single pulse shock tube at temperatures of 870-1145K and pressures of 2-9 bar. Stable products from various reaction channels (terminal and non-terminal H addition, and

Computational Analysis of Dynamic SPK(S8)-JP8 Fueled Combustor-Sector Performance

April 9, 2010
Author(s)
R. Ryder, Robert C. Hendricks, Marcia L. Huber, D. T. Shouse
Civil and military flight tests using blends of synthetic and biomass fueling with jet fuel up to 50:50 are currently considered as drop in fuels. They are fully compatible with aircraft performance, emissions and fueling systems, yet the design and

Density and Speed of Sound Measurements of Hexadecane

January 7, 2010
Author(s)
Stephanie L. Outcalt, Arno R. Laesecke, Tara J. Fortin
The density and speed of sound of hexadecane have been measured using two instruments. Both instruments use the vibrating-tube method for measuring density. Ambient pressure (83 kPa) density and speed of sound measurements were carried out with a rapid

IMMOBILIZED ENZYME CATALYZED POLYMERIZATION REACTIONS IN MICROREACTORS

January 1, 2010
Author(s)
Santanu S. Kundu, Atul Bhangale, William E. Wallace, Kathleen M. Flynn, Richard Gross, Kathryn L. Beers
Application of microreactor technologies enable improved safety, selectivity and yield in a range of chemical reactions in addition to new measurement methods that are often faster, cheaper and more accurate than traditional methods. In this study we have

IMPACT OF IMMOBILIZATION SUPPORTS FOR POLYESTERS SYNTHESIS ACTIVITY OF CANDIDA ANTARTICA LIPASE B

January 1, 2010
Author(s)
Atul Bhangale, Santanu S. Kundu, Wenchun Xie, William E. Wallace, Kathleen M. Flynn, Kathryn L. Beers, Richard Gross
Epoxy functionalized supports are known to be suitable for industrial-scale immobilization of enzymes for biocatalysis. However, chemistry across these epoxy groups is known to affect the catalytic performance of the enzymes.In order to achieve a balance

Optimizing Acoustic Measurements of the Boltzmann Constant

November 22, 2009
Author(s)
Michael R. Moldover
We review the progress in acoustic metrology of gases that has occurred since the 1988 measurement of the universal gas constant R using a spherical acoustic resonator. The advances in understanding resonators and in calculating the thermophysical

Perturbations from Ducts on the Modes of Acoustic Thermometers

September 1, 2009
Author(s)
Keith A. Gillis, Michael R. Moldover, Hong Lin
We examine the perturbations of the modes of an acoustic thermometer caused by circular ducts used either for gas flow or as acoustic waveguides coupled to remote transducers. We calculate the acoustic admittance of circular ducts using a model based on

Reference measurements of Hydrogen's Dielectric Permittivity

August 10, 2009
Author(s)
James W. Schmidt, Michael R. Moldover, Eric F. May
We used a quasi-spherical cavity resonator to measure the relative dielectric permittivity ε r of H 2 at frequencies from 2.4 GHz to 7.3 GHz, at pressures up to 6.5 MPa, and at the temperatures 273 K and 293 K. The resonator was calibrated using auxiliary

High Definition Flow

August 1, 2009
Author(s)
John D. Wright, Michael R. Moldover
From pharmaceutical production to the natural gas market, exact flow measurements are critical. Here's how NIST helps keep us all on the same page.

Optimization Calculations for a 30 HZ, 4 K Regenerator with Helium-3 Working Fluid

June 28, 2009
Author(s)
Ray Radebaugh, Yonghua Huang, Agnes A. O'Gallagher, John M. Gary
The NIST numerical software, REGEN3.3, which incorporates both He-4 and He-3 properties, was used to calculate the losses and second law efficiencies of 4 K regenerators operating at 30 Hz. Operating parameters, such as average pressure, pressure ratio

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
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