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Displaying 426 - 450 of 2028

Surface interaction parameter measurement of solvated polymers via model end-tethered chains

August 11, 2017
Author(s)
Richard J. Sheridan, Sara V. Orski, Ronald L. Jones, Sushil K. Satija, Kathryn L. Beers
We present a method for the direct measurement of the relative energy of interaction between a solvated polymer and a solid interface. By tethering linear chains covalently to the surface, we ensured the idealized and constant configuration of polymer

On Neutron Activation Analysis with Gamma,Gamma Coincidence Spectrometry

July 26, 2017
Author(s)
Rolf L. Zeisler, Hana Cho, Ibere Souza Ribeiro Junior, Martin G. Shetty, Danyal J. Turkoglu
A new  coincidence system has been set up at NIST. It is operated with a digital data finder supported by new software developed at NIST. The system is used to explore possible enhancements in instrumental neutron activation analysis (INAA) and study

Exposure to Engineered Nanomaterials: Impact on DNA Repair Pathways

July 13, 2017
Author(s)
Neenu Singh, Bryant C. Nelson, Leona D. Scanlan, Erdem Coskun, Pawel Jaruga, Shareen Doak
Some engineered nanomaterials (ENMs) may have the potential to cause damage to the genetic material in living systems. The mechanistic machinery functioning at the cellular/molecular level, in the form of DNA repair processes, has evolved to help

Photochemical Properties of CH2=CH-CFCl-CF2Br (4-bromo-3-chloro-3,4,4-trifluoro-1-butene) and CH3-O-CH-(CF3)2 (methyl 2,2,2-trifluoroethyl-1-trifluoromethyl ether): OH Reaction Rate Constant, UV and IR Absorption Spectra.

July 7, 2017
Author(s)
Vladimir L. Orkin, Larissa E. Martynova, Michael J. Kurylo III
Abstract Rate constants for the reactions of hydroxyl radicals (OH) with methyl 2,2,2-trifluoroethyl-1-trifluoromethyl ether (CH3-O-CH-(CF3)2 and 4-bromo-3-chloro-3,4,4-trifluoro-1-butene (CH2=CH-CFCl-CF2Br) have been measured over the temperature range

Qualitative characterization of SRM 1597a Coal Tar for polycyclic aromatic hydrocarbons and methyl-substituted derivatives via normal-phase liquid chromatography and gas chromatography/mass spectrometry

June 29, 2017
Author(s)
Walter B. Wilson, Hugh Hayes, Lane C. Sander, Andres Campiglia, Stephen A. Wise
A normal-phase liquid chromatography (NPLC) fractionation procedure was developed for the characterization of a complex mixture of polycyclic aromatic hydrocarbons (PAHs) from a coal tar sample (Standard Reference Material (SRM) 1597a). Using a semi

Revisiting Shape Selectivity in Liquid Chromatography for Polycyclic Aromatic Hydrocarbons (PAHs) - Six-Ring and Seven-Ring Cata-condensed PAH Isomers of Molecular Mass 328 Da and 378 Da

June 28, 2017
Author(s)
Jorge O. Ona Ruales, Lane C. Sander, Walter Brent Wilson, Stephen Wise
The relationship of reversed-phase liquid chromatography retention on a polymeric C18 stationary phase and the shape of polycyclic aromatic hydrocarbons (PAHs) was investigated for three-ring to seven-ring cata-condensed isomers. We report the first

Associations between perfluorinated alkyl acids measured in blood and ovarian follicular fluid and ovarian function in women undergoing assisted reproductive treatment

June 26, 2017
Author(s)
Jessica A. Cloy-McCoy, Jacqueline T. Bangma, Jessica L. Reiner, John Bowden, John Schnorr, Michael Slowey, Tom O'Leary, Louis J. Guillette, Benjamin B. Parrott
Endocrine disrupting contaminants, in combination with other environmental variables, are associated with altered reproductive health. Assisted reproductive technology (ART) procedures offer valuable opportunities to explore the connections between

SI traceable determination of arsenic species in kelp (Thallus laminariae)

June 26, 2017
Author(s)
Lee L. Yu, Rolf L. Zeisler, Rachel C. Stanoyevitch
Kelp is a dietary supplement that contains significant amount of arsenic. Accurate assessment of dietary safety of kelp requires the determination of the arsenic species therein. A procedure was developed to extract the hydrophilic fraction of arsenicals

Normal-phase liquid chromatography retention behavior of polycyclic aromatic hydrocarbon and their methyl-substituted derivatives on an aminopropyl stationary phase

June 16, 2017
Author(s)
Walter B. Wilson, Hugh Hayes, Lane C. Sander, Andres D. Campiglia, Stephen A. Wise
Retention indices for 124 polycyclic aromatic hydrocarbons (PAHs) and 62 methyl-substituted (Me-) PAHs were determined using normal-phase liquid chromatography (NPLC) on a aminopropyl (NH2) stationary phase. PAH retention behavior on the NH2 phase is

Metabolomics Analysis of Effects of Commercial Soy-based Protein Products in Red Drum (Sciaenops ocellatus)

June 14, 2017
Author(s)
Fabio Casu, Aaron Watson, Justin Yost, John Leffler, Gibson Gaylord, Frederic Barrows, Paul A. Sandifer, Dan Bearden, Michael R. Denson
In this study we investigated the metabolic effects of four different commercial soy-based protein products on red drum (Sciaenops ocellatus) using NMR-based metabolomics along with unsupervised principal component analysis (PCA) to evaluate metabolic

Partial Ionization Cross Sections of Organic Molecules

June 13, 2017
Author(s)
Karl K. Irikura
Partial ionization cross sections are the absolute yields of specific ions from an electron- molecule collision. They are necessary for modeling plasmas and for determining the sensitivity of mass spectrometers, among other applications. One mass

Determination of the molar mass of argon from a high precision acoustic comparison

May 18, 2017
Author(s)
XiaoJuan Feng, Jintao Zhang, Michael R. Moldover, Inseok Yang, Mark Plimmer, H. Lin
This article describes the accurate determination of the molar mass of a sample of argon gas used for a determination of the Boltzmann constant. The method due to one of the authors [Moldover et al., J. Res. Natl. Bur. Stand. 93, 85-144 (1988)] uses the

Conformational Changes in Active and Inactive States of Human PP2C? characterized by Hydrogen/Deuterium Exchange-Mass Spectrometry

May 8, 2017
Author(s)
Sharlyn Mazur, Elyssia S. Gallagher, Subrata Debnath, Stewart R. Durell, Kyle Anderson, Lisa M. Jenkins, Ettore Appella, Jeffrey W. Hudgens
PPM serine/threonine protein phosphatases function in signaling pathways and require millimolar concentrations of Mn2+ or Mg2+ ions for activity. Whereas the crystal structure of human PP2Cα displayed two tightly bound Mn2+ ions in the active site, recent

DART-MS analysis of inorganic explosives using high temperature thermal desorption

May 4, 2017
Author(s)
Thomas P. Forbes, Edward R. Sisco, Matthew E. Staymates, John G. Gillen
An ambient mass spectrometry (AMS) platform coupling Joule heating thermal desorption (JHTD) and direct analysis in real time (DART) was developed, generating discretely pulsed rapid heating ramps and elevated temperatures for the detection of inorganic
Displaying 426 - 450 of 2028