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Chemistry

Analytical chemistry

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Displaying 576 - 600 of 2094

Alterations in eicosanoid composition during embryonic development in the chorioallantoic membrane of the American alligator (Alligator mississippiensis) and domestic chicken (Gallus gallus)

November 1, 2016
Author(s)
John Bowden, Theresa M. Cantu, Jacob Scott, Jimena B. Perez-Viscasillas, Kevin M. Huncik, Matthew P. Guillette, Louis J. Guillette Jr.
Eicosanoids are signaling lipids that regulate several physiological processes in the mammalian placenta, including the initiation of parturition. Though all amniotes construct similar extraembryonic membranes during development, the composition and

Gas Uptake of 3-D Printed Acrylonitrile Butadiene Styrene (ABS) Using a Vacuum Apparatus Designed for Absorption and Desorption Studies

October 25, 2016
Author(s)
Makfir Sefa, Zeeshan Ahmed, James A. Fedchak, Nikolai Klimov, Julia Scherschligt
We describe a vacuum apparatus for determining the outgassing rate into vacuum, the diffusion coefficient, and the amount of gas absorbed for various materials. The diffusion coefficient is determined from a model applied to time-dependent desorption data

Avian mercury exposure and toxicological risk across western North America: a synthesis

October 15, 2016
Author(s)
Joshua T. Ackerman, Collin A. Eagles-Smith, Mark P. Herzog, Alex Hartman, Sarah Peterson, David C. Evers, Allyson Jackson, John E. Elliott, Stacy Schuur, Colleen E. Bryan Sallee
Methylmercury contamination of the environment is an important issue globally and birds are useful bioindicators for mercury monitoring programs. We synthesized all of the available data on mercury contamination of birds in western North America. We

Mercury Risk to Avian Piscivores across the Western United States and Canada

October 15, 2016
Author(s)
Allyson Jackson, David C. Evers, Collin A. Eagles-Smith, Joshua T. Ackerman, James J. Willacker, John E. Elliott, Stacy Schuur, Colleen E. Bryan Sallee
As part of the Western North America Mercury Synthesis, we evaluated risk to avian piscivores across all or parts of their breeding range through the compilation of fish and bird tissue mercury (Hg) concentrations for western United States and Canada. We

Identification of the Crystal Symmetry in 1T' MoTe2 with Polarization-Resolved Second Harmonic Generation and Raman Scattering

October 13, 2016
Author(s)
Ryan Beams, Luiz Gustavo Cancado, Sergiy Krylyuk, Irina Kalish, Berc Kalanyan, Arunima Singh, Kamal Choudhary, Patrick Vora, Francesca M. Tavazza, Albert Davydov, Stephan J. Stranick
We study the crystal symmetry properties of few-layer 1T' MoTe2 using the polarization dependence of the second harmonic generation (SHG) and Raman scattering. Bulk 1T' MoTe2 is know to be inversion symmetric, however, we nd that the inversion symmetry is

Supramolecular Hemicage Cobalt Mediators for Efficient and Stable Dye-Sensitized Solar Cells

October 11, 2016
Author(s)
Lisa A. Fredin, Marina Freitag, Wenxing Yang, Luca D' Amario, K. Martin Karlsson, Anders Hagfeldt, Gerrit Boschloo
A new class of DSCs using the hemicage cobalt based mediator [Co(ttb)] 2+/3+ using the hexadentate ligand 5,5'',5''''-((2,4,6- triethyl highly preorganized benzene-1,3,5-triyl)tris(ethane-2,1- diyl))tri-2,2'- bipyridine (ttb) were studied. Current-voltage

Light Source Effects on Aerosol Photoacoustic Spectroscopy Measurements

October 6, 2016
Author(s)
James G. Radney, Christopher D. Zangmeister
Photoacoustic spectroscopy measurements of flame-generated soot aerosol coated with small amounts of water yielded absorption enhancements that were dependent on the laser used: quasi- continuous wave (Q-CW, ≈ 650 ps pulse duration and 78 MHz repetition

The rheo-Raman microscope: Simultaneous chemical, conformational, mechanical, and microstructural measures of soft materials

October 4, 2016
Author(s)
Anthony P. Kotula, Matthew Meyer, Francesca De Vito, Jan Plog, Angela R. Hight Walker, Kalman D. Migler
We describe the design and demonstrate performance of an instrument capable of simultaneous Raman spectroscopy, rheology, and optical microscopy of materials. The instrument couples a Raman microscope with a rotational rheometer through an optically

Theory and Experiment of Binary Diffusion Coefficient of n-Alkanes in Dilute Gases

September 27, 2016
Author(s)
Changran Liu, William S. McGivern, Jeffrey A. Manion, Hai Wang
Binary diffusion coefficients were measured for n-pentane, n-hexane and n-octane in helium and of n-pentane in nitrogen over the temperature range of (300 - 600) K, using reversed-flow gas chromatography. A generalized, analytical theory was proposed for

Interlaboratory Analytical Comparison of Fatty Acid Concentrations in Serum or Plasma

September 20, 2016
Author(s)
Michele M. Schantz, Carissa Powers, Schleicher Rosemary, Joseph Betz, Stephen A. Wise
The National Institute of Standards and Technology, in collaboration with the National Institutes of Health Office of Dietary Supplements and the Centers for Disease Control and Prevention, is conducting an accuracy-based program for improving the

NIST Electron Elastic-Scattering Cross-Section Database, Version 4.0

September 14, 2016
Author(s)
Cedric J. Powell, Aleksander Jablonski, Francesc Salvat, Angela Y. Lee
Version 4.0 of this database (SRD 64) provides values of differential elastic-scattering cross sections, total elastic-scattering cross sections, phase shifts, and transport cross sections for elements with atomic numbers from 1 to 96 and for electron

INVESTIGATION OF URBAN ROCK VARNISH ON THE SANDSTONE OF THE SMITHSONIAN CASTLE

September 6, 2016
Author(s)
Richard A Livingston, Carol A. Grissom, Edward Vicenzi, Zoe Weldon-Yochim, Nicole Little, Janet Douglas, Alexandre Fowler, Cara Santelli, Dorothea Macholdt, Diana Ortiz-Montalvo, Stephanie S. Watson
Bluish black, highly adherent patches have been observed growing on the Seneca sandstone of the Smithsonian Castle in Washington, DC. They are significantly enriched in Mn compared to the underlying sandstone, by a factor of 100, which suggests that

NIST Micronutrients Measurement Quality Assurance Program Analysis Tutorial

September 6, 2016
Author(s)
Katherine E. Sharpless, Jeanice M. Brown Thomas, David L. Duewer
Since 1984, the National Institute of Standards and Technology (NIST) has coordinated what is now known as the Micronutrients Measurement Quality Assurance Program (MMQAP) for laboratories that measure fat-soluble vitamins and carotenoids in human serum

Broadband Coherent Anti-Stokes Raman Scattering

August 11, 2016
Author(s)
Charles H. Camp
Broadband coherent anti-Stokes Raman scattering (BCARS) microspectroscopy is a unique label-free imaging modality that provides detailed chemical information at each pixel. In minutes, this technique captures a “hyperspectral” cube that co-registers
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