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Displaying 451 - 475 of 1934

Towards a dynamic pressure standard based on laser absorption spectroscopy

May 20, 2016

Author(s)

Kevin O. Douglass, Douglas A. Olson

We describe an approach for creating a cost-effective, field deployable dynamic pressure standard based on measurement of fundamental quantum properties of molecular systems. From the linewidth and intensities of ro-vibrational transitions we plan on

Mass Spectrometry of Analytical Derivatives. 2. Ortho and Para Effects in Electron Ionization Mass Spectra of Derivatives of Hydroxyl, Mercapto and Amino Benzoic Acids

May 1, 2016

Author(s)

Nino G. Todua, Anzor I. Mikaia

Derivatives requiring either anhydrous or aqueous reaction conditions were prepared for robust and reliable gas chromatography mass spectrometry (GC-MS) characterization of hydroxyl, mercapto, and amino benzoic acids. Methylation and trialkylsilylation

Speed of Sound Measurements in (Argon + Carbon Dioxide) over the Temperature Range from (275 to 500) K at Pressures up to 8 MPa

March 23, 2016

Author(s)

Mark O. McLinden, Richard A. Perkins, Robin Wegge, Markus Richter, Roland Span

The speed of sound of two (argon + carbon dioxide) mixtures was measured over the temperature range from (275 to 500) K with pressures up to 8 MPa utilizing a spherical acoustic resonator. The compositions of the gravimetrically prepared mixtures were (0

Predicting Structures of Ru-Centered Dyes: A Computational Screening Tool

March 16, 2016

Author(s)

Lisa A. Fredin, Thomas C. Allison

Dye-sensitized solar cells (DSCs) represent a viable means for harvesting solar energy to produce electrical power. Though a number of light harvesting dyes are in use, the search continues for more efficient and effective compounds to make commercially

Analysis of Human Plasma Metabolites across Different Liquid Chromatography - Mass Spectrometry Platforms

March 15, 2016

Author(s)

Kelly H. Telu, Xinjian Yan, William E. Wallace, Stephen Stein, Yamil Simon

The development of increasingly sensitive analytical techniques has renewed interest in global metabolite profiling, i.e., the semi-quantitative monitoring of all the chemical constituents of biological fluids. In this work, global metabolite profiles of

Method Validation and Standards in Hydrogen/Deuterium Exchange Mass Spectrometry

March 1, 2016

Author(s)

Jeffrey W. Hudgens, Richard Y. Huang, Emma D'Ambro

The chapter examines method validation and measurement standards for measuring protein dynamics by hydrogen/deuterium exchange mass spectrometry. Topics examined include the rationale for a reference measurement system for HDX-MS, attaining high accuracy

Field Portable Low Temperature Porous Layer Open Tubular Cryoadsorption Headspace Sampling and Analysis Part II: Applications*

February 16, 2016

Author(s)

Megan Harries, Santiago Bukovsky-Reyes, Thomas J. Bruno

This paper details the sampling methods used with the field portable PLOT-cryoadsorption (PLOT-cryo) approach, described in Part I of this two-part series, applied to several analytes of interest. We conducted tests with coumarin and 2,4,6-trinitrotoluene

Thermodynamic Properties of Polycyclic Aromatic Hydrocarbons

December 16, 2015

Author(s)

Thomas C. Allison, Donald R. Burgess Jr.

Polycyclic aromatic hydrocarbons (PAHs) are molecules that exist on earth due to natural and man-made causes. They are a significant health concern as many PAH compounds are known to be carcinogenic. PAHs are generally thermodynamically stable and

Particle Fabrication Using Inkjet Printing onto Hydrophobic Surfaces for Optimization and Calibration of Trace Contraband Detection Sensors

November 24, 2015

Author(s)

John G. Gillen, Marcela N. Najarro, Matthew E. Staymates, Scott A. Wight, Marlon L. Walker, Jennifer R. Verkouteren, Eric S. Windsor, Aaron A. Urbas

A method has been developed to fabricate patterned arrays of micrometer-sized monodisperse solid particles of ammonium nitrate on hydrophobic silicon surfaces using inkjet printing. The method relies on dispensing one or more microdrops (typically 50 pL

First far-infrared high resolution analysis of the nu6 band of phosgene 35Cl2CO and 35Cl37CLCO

November 2, 2015

Author(s)

Walter J. Lafferty

A Fourier transform spectrum of phosgene (Cl2CO) has been recorded in the 22.5 μm spectral region at a resolution of 0.00102 cm-1 using a Bruker IFS125HR spectrometer coupled with synchrotron radiation leading to the observation of the ν6 vibrational bands

Thermal Signature Measurements for Ammonium Nitrate/Fuel Mixtures by Laser Heating

November 1, 2015

Author(s)

Cary Presser

Measurements were carried out to obtain thermal signatures of several ammonium nitrate/fuel (ANF) mixtures, using a laser-heating technique referred to as the laser-driven thermal reactor (LDTR). The mixtures were ammonium nitrate (AN)/kerosene, AN

HOW OLD IS IT? - 241PU/AMNUCLEAR FORENSIC CHRONOLOGY REFERENCE MATERIALS

October 27, 2015

Author(s)

Ryan P. Fitzgerald, Kenneth G. Inn

One material attribute for nuclear forensics is material age. 241Pu is almost always present in uranium- and plutonium-based nuclear weapons, which pose the greatest threat to our security. The in-growth of 241Am due to the decay of 241Pu provides an

Quantifying Trace 2,4,6-Trinitrotoluene (TNT) in Polymer Microspheres

October 16, 2015

Author(s)

Timothy M. Brewer, Robert A. Fletcher, Matthew E. Staymates

Well characterized test materials are essential for validating the performance of current trace explosive detection systems. Explosive encapsulated microspheres have proven to be a valuable test material for trace explosive detection because their precise

CCQM Pilot Study P-140; Quantitative Surface Analysis of Multi-Element Alloy Films

October 1, 2015

Author(s)

David S. Simons, Christopher W. Szakal, William A. Osborn, Kyung Joong Kim

A pilot study for the quantitative surface analysis of multi-element alloy films has been performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The aim of this pilot study is to ensure the

Standardizing 25-Hydroxyvitamin D values from the Canadian Health Measures Survey

September 30, 2015

Author(s)

Kurtis Sarafin, Ramon Durazo-Arvizu, Lu Tian, Karen W. Phinney, Susan Tai, Johanna Camara, Hubert W. Vesper, Joyce M. Merkel, Evan Green, Christopher T. Sempos, Stephen P. Brooks

Background: The Canadian Health Measures survey (CHMS) is an ongoing cross sectional national survey that includes a measure of 25-hydroxyvitamin D (25(OH)D) by Diasorin LIAISON immunoassay. The survey repeats approximately every two years with a new

Reparameterization of COSMO-SAC for Phase Equilibrium Properties Based on Critically Evaluated Data

September 25, 2015

Author(s)

Yauheni Paulechka, Vladimir Diky, Andrei F. Kazakov, Kenneth G. Kroenlein, Michael D. Frenkel

COSMO-SAC model was re-parameterized using the critically evaluated data generated by the NIST ThermoData Engine for vapor-liquid equilibria, excess enthalpies for binary mixtures, and activity coefficients of components of binary mixtures. The calculated

Time-resolved terahertz spectroscopy (TRTS) of electrically conductive metal-organic frameworks (MOFs) doped with redox active species

September 24, 2015

Author(s)

Brian G. Alberding, Edwin J. Heilweil

Metal-Organic Frameworks (MOFs) are three-dimensional coordination polymers that are well known for large pore surface area and their ability to adsorb molecules from both the gaseous and solution phases. In general, MOFs are electrically insulating, but

Retention projection enables accurate calculation of liquid chromatographic retention times across labs and methods

September 3, 2015

Author(s)

Yamil Simon, Daniel Abate-Pella, Dana M. Freund, Yan Ma, Adrian Hegeman, Yan Ma, Tobias Kind, O Fiehn, Birgit Beck, Emma L. Schymanski, Corey D. Broeckling, David V. Huhman, Lloyd W. Summer, Oleg V. Krokhin, Dwight R. Stoll

Identification of small molecules by liquid chromatography-mass spectrometry (LC-MS) could be greatly improved if the chromatographic retention information could be used along with mass spectral information to narrow down the lists of potential identities

Role of Elastic Strain on Electrocatalysis of Oxygen Reduction Reaction on Pt

July 23, 2015

Author(s)

Gery R. Stafford, Vijay Sethuraman, Deepa Vairavapandian, Manon C. Lafouresse, Tuhina Maark, Naba Karan, Shouheng Sun, Ugo Bertocci, Andrew Peterson, Pradeep Guduru

The effect of elastic strain on catalytic activity of platinum (Pt) towards oxygen reduction reaction (ORR) is investigated through de-alloyed Pt-Cu thin films; stress evolution in the de-alloyed layer and the mass of the Cu removed are measured in real

Kinetics of the Reactions of H and CH3 with n-Alkanes: Experiments with n-Butane and a Reevaluation Based on a Combustion Model Reaction Network Analysis

July 16, 2015

Author(s)

Jeffrey A. Manion, David A. Sheen, Iftikhar A. Awan

Presented is a combined experimental and modeling study of the kinetics of the reactions of H and CH3 with n-butane, a representative aliphatic fuel. Abstraction of H from n-alkane fuels creates alkyl radicals that rapidly decompose at high temperatures to

Spherical Resonator for Vapor-Phase Speed of Sound and Measurements of 1,1,1,2,2,3,3-heptafluoro-3-methoxypropane (RE347mcc) and trans-1,3,3,3-tetrafluoropropene [R1234ze(E)]

July 14, 2015

Author(s)

Richard A. Perkins, Mark O. McLinden

We describe an apparatus to measure the speed of sound of gas samples at temperatures from 265 K to 500 K with pressures up to 40 MPa. The speed of sound is determined from the frequency of the three lowest-order radial resonance modes for the gas in a

Bubble-Point Measurements of n?Butane + n?Octane and n?Butane + n-Nonane Binary Mixtures

June 30, 2015

Author(s)

Elisabeth Mansfield, Stephanie L. Outcalt

Mixtures of small gaseous hydrocarbons with longer chain hydrocarbons are of interest to the natural gas industry. In particular, binary mixtures of nonane are of particular interest, as nonane was just incorporated into the GERG-2008 equation of state

Analytical Methods for Determination of Polycyclic Aromatic Hydrocarbons (PAHs) A Historical Perspective on the 16 US EPA Priority Pollutant PAHs

June 16, 2015

Author(s)

Stephen A. Wise, Lane C. Sander, Michele M. Schantz

Since identified as priority pollutants by the U.S. Environmental Protection Agency (EPA) in 1979, the 16 EPA polycyclic aromatic hydrocarbons (PAHs) have been a key motivation for analytical methods development for the determination of PAHs. In this

Chlorine - Bromine Combination Isotope Intensities

June 9, 2015

Author(s)

Thomas J. Bruno

Due to the distinctive mass spectral patterns caused by the presence of chlorine and bromine in a molecule, interpretation of a mass spectrum can be much easier if the results of the relative isotopic concentrations are known. The following table provides

Gas Chromatographic Retention Indices

June 9, 2015

Author(s)

Thomas J. Bruno

The interpretation of results from chromatographic measurements can often be augmented with an appropriate mathematical treatment of the solute retention that is observed. The goal of treatment is to make the resulting metric as independent of the