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Displaying 401 - 425 of 1931

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

Analytical Methods and Development of Reference Materials for Toxic Metals and Metal Species in Food and Dietary Supplements

September 18, 2017
Author(s)
Stephen E. Long, Michael B. Ellisor, Frances Nilsen, Laura J. Wood, Karen E. Murphy, Lee L. Yu
Highly toxic metals such as arsenic, cadmium, lead and mercury are prevalent in the terrestrial and marine environments from both natural sources and anthropogenic activities. Contamination of food can often occur during agricultural production and food

Ionizing Radiation Processing and its Potential in Advancing Biorefining and Nanocellulose Composite Materials Manufacturing

September 1, 2017
Author(s)
Michael T. Postek, Dianne L. Poster, Andras Vladar, Mark S. Driscoll, Jay A. LaVerne, Zios Tsinas, Mohamad Al-Sheikhly
Nanocellulose is a high value material that has gained increasing attention because of its high strength, stiffness, unique photonic and piezoelectric properties, high stability and uniform structure. Through utilization of a biorefinery concept

Baseline Assessment of 25-Hydroxyvitamin D Assay Performance: A Vitamin D Standardization Program (VDSP) Interlaboratory Comparison Study

August 18, 2017
Author(s)
Christopher T. Sempos, Stephen Wise, Karen W. Phinney, Susan Tai, Johanna Camara, Gary L. Myers, Ramon Durazo-Arvizu, Lu Tian, John H. Eckfeldt, Andrew N. Hoofnagle, W. Greg Miller, Lorin M. Bachmann, Ian S. Young, J Pettit, G. Caldwell, A Liu, S P. Brooks, K. Sarafin, M. Thamm, C. Scheidt-Nave, G. B. Mensink, M. Busch, M. Rabenberg, Kevin Cashman, Mairead Kiely, Michael Kinsella, K Galvan, J. Y. Zhang, K OH, S. W. Lee, C. L. Jung, L. Cox, G. Goldberg, K. Guberg, S. Meadows, A. Prentice, G. Swan, A. Tedstone, Graham D. Carter, Julia C. Jones, P. Brannon, R. M. Lucas, P. M. Crump, Glenville Jones, E. Cavalier, Joyce Merkel, J. M. Betz
The Vitamin D Standardization Program (VDSP) coordinated an interlaboratory study to assess the comparability of measurements of total 25-hydroxyvitamin D [25(OH)D] in human serum, which is the primary marker of vitamin D status. A set of 50 individual

Development of Standard Reference Material (SRM) 2973 Vitamin D Metabolites in Frozen Human Serum (High Level)

July 24, 2017
Author(s)
Susan Tai, Michael Nelson, Brian Lang, Karen W. Phinney, Lane C. Sander, James H. Yen, J. M. Betz, Christopher T. Sempos, Stephen Wise
The National Institute of Standards and Technology (NIST), in collaboration with the National Institutes of Health, Office of Dietary Supplements (NIH-ODS) and the Vitamin D Standardization Program (VDSP), has recently issued a new serum-matrix Standard

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

Cannabinoid Vapor Pressures to Aid in Vapor Phase Detection of Intoxication

June 27, 2017
Author(s)
Tara Lovestead, Thomas J. Bruno
The quest for a reliable means to detect cannabis intoxication with a br eathalyzer is ongoing. In order to design such a device, it is important to understand the basic fundamental thermodynamics of the compounds of interest. Herein, the vapor pressures

The 2016 edition of the Art in Science of MicroTAS

April 21, 2017
Author(s)
Darwin R. Reyes-Hernandez
Dublin, Ireland beheld The 20th International Conference of Miniaturized Systems for Chemistry and Life Sciences (MicroTAS 2016) from October 23 to 27, 2016. The conference not only included a great technical program, but also outreach activities, an

Standardized Measurements of Collection Efficiency from Wipe-Sampling of Trace Explosives

April 10, 2017
Author(s)
Jennifer R. Verkouteren, Jeffrey A. Lawrence, Matthew E. Staymates, Edward R. Sisco
One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common procedure for collecting traces of explosives, and standardized measurements of collection efficiency

Efficient Simulation of Secondary Fluorescence via NIST DTSA-II Monte Carlo

March 17, 2017
Author(s)
Nicholas Ritchie
Secondary fluorescence, the final term in the familiar matrix correction triumvirate Z·A·F, is the most challenging for Monte Carlo models to simulate. In fact, only two implementations of Monte Carlo models commonly used to simulate electron probe x-ray
Displaying 401 - 425 of 1931
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