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Chemistry

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Displaying 376 - 400 of 1924

An Iterative Qualitative - Quantitative Sequential Analysis Strategy for Electron-Excited X-ray Microanalysis with Energy Dispersive Spectrometry: Finding the Unexpected Needles in the Peak Overlap Haystack

June 20, 2018
Author(s)
Dale E. Newbury, Nicholas Ritchie
When analyzing an unknown by electron-excited energy dispersive X-ray spectrometry with the entire periodic table possibly in play, how does the analyst discover minor and trace constituents when their peaks are overwhelmed by the intensity of an

Final Report for CCQM-K6.2: Determination of Total Cholesterol in Human Serum

June 7, 2018
Author(s)
Stephen Wise, Karen W. Phinney, David L. Duewer
Cholesterol is one of the most frequently measured substances in human blood/serum to assist in assessing the health status of individuals. Because of its clinical significance, CCQM-K6 Determination of Cholesterol in Serum was completed in 2000 as one of

EDS Microanalysis: Pushing the Limits

June 1, 2018
Author(s)
Nicholas Ritchie, Dale E. Newbury, Michael Mengason, Heather Lowers
It is a great time to be a microanalyst. After a few decades of incremental progress in energy dispersive X-ray spectrometry (EDS), the last decade has seen the accuracy and precision surge forward. Today, the question is not whether EDS is generally

Absence of diffuse double layer effect on the vibrational properties and oxidation of chemisorbed carbon monoxide on a Pt(111) electrode

May 23, 2018
Author(s)
Marta C. Figueiredo, Dennis Hiltrop, Ravishankar Sundararaman, Kathleen Schwarz, Marc Koper
In this work we investigate the effects of the diffuse double layer thickness on the electrochemical Stark tuning and oxidation of carbon monoxide at Pt(111) surfaces in perchloric acid solution. The diffuse double layer thickness was modified by changing

Kinetics of H Atom Addition to Cyclopentene

March 7, 2018
Author(s)
Jeffrey A. Manion, Iftikhar A. Awan
To provide benchmark information needed to develop kinetic models of the combustion and pyrolysis of hydrocarbon ring structures, we have used the single pulse shock tube technique to study the kinetics of H atom addition to cyclopentene at 863 K to 1167 K

Standard Reference Material 2378 Fatty Acids in Frozen Human Serum. A Clinical SRM based on Endogenous Supplementation of Polyunsaturated Fatty Acids

February 13, 2018
Author(s)
Bruce A. Benner Jr., Michele M. Schantz, Johanna Camara, Katherine E. Sharpless, James H. Yen, Lorna T. Sniegoski, Carissa D. Powers, Rosemary L. Schleicher
Dietary fatty acids can be both beneficial and detrimental to human health depending on the degree and type of saturation. Healthcare providers and research scientists monitor the fatty acid content of human plasma and serum as an indicator of health

Contrasting Transport and Electrostatic Properties of Selectively Fluorinated Alkanethiol Monolayers with Embedded Dipoles

February 7, 2018
Author(s)
Robert C. Bruce, Lin You, Anja Forster, Sujitra J. Pookpanratana, Olivia Pomerenk, Han Ju Lee, Maria D. Marquez, Rashid Ghanbaripour, Oussama Zensani, T R. Lee, Christina A. Hacker
Surface dipoles are a powerful tool in interfacial modification for improving device output via energy level matching. Fluorinated alkanethiols show strong promise for these applications as they can generate large and tunable dipoles based on fluorine

A Shock Tube Study of H Addition to Cyclopentene

February 1, 2018
Author(s)
Jeffrey A. Manion, Iftikhar A. Awan
The kinetics of H atom addition to cyclopentene has been studied with a single pulse shock tube at temperatures of (863 to 1167 K) and pressures of (160 to 370) kPa. Hydrogen atoms were generated with thermal precursors in dilute mixtures of cyclopentene

Analysis of PFAAs in American alligators Part 1: Concentrations in alligators harvested for consumption during South Carolina public hunts.

November 29, 2017
Author(s)
Jessica Tipton, Louis J. Guillette, Benjamin B. Parrott, Thomas R. Rainwater, Jessica L. Reiner
Environmental contamination resulting from the production or release of harmful chemicals can lead to negative consequences for wildlife and human health. Perfluorinated alkyl acids (PFAAs) were historically produced as protective coatings for many

Collision-Induced Dissociation of Deprotonated Peptides. Relative Abundance of Side-Chain Neutral Losses, Residue-Specific Product Ions, and Comparison with Protonated Peptides

November 14, 2017
Author(s)
Yuxue Liang, Pedatsur Neta, Xiaoyu (Sara) Yang, Stephen E. Stein
High-accuracy MS/MS spectra of deprotonated ions of 390 dipeptides and 137 peptides with 3 to 6 residues are studied. Many amino acid residues undergo neutral losses from their side chains. The most abundant is the loss of acetaldehyde from threonine. The

Gas Chromatographic Retention Behavior of Polycyclic Aromatic Hydrocarbons (PAHs) and Alkyl- Substituted PAHs on Two Stationary Phases of Different Selectivity

November 8, 2017
Author(s)
Federica Nalin, Lane C. Sander, Walter B. Wilson, Stephen A. Wise
Retention indices (RIs) for 45 polycyclic aromatic hydrocarbons (PAHs) and 63 methyl- substituted PAHs were determined by gas chromatography – mass spectrometry (GC-MS) using two different stationary phases: a 50% (mole fraction) phenyl-substituted

Integrated Optical Waveguides for in situ Microflow Measurements

October 15, 2017
Author(s)
James R. Hands, Gregory A. Cooksey
The need for quantitative microscale chemical and biological experiments has resulted in the increasing utilization of microfluidics with integrated sensors, allowing such architectures to synergistically enhance function and performance [1]. This work

Redox-active Nanomaterials for Nanomedicine Applications

October 6, 2017
Author(s)
Christopher Sims, Shannon Hanna, Daniel A. Heller, Christopher Horoszko, Monique Johnson, Antonio Montoro Bustos, Vytas Reipa, Kathryn Riley, Bryant C. Nelson
Nanomedicine utilizes the remarkable properties of nanomaterials for the diagnosis, treatment, and prevention of disease. Many of these nanomaterials have been shown to have robust antioxidative properties, potentially functioning as strong scavengers of
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