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Chemistry

Analytical chemistry

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Displaying 851 - 875 of 2086

Correlation of rocket propulsion fuel properties with chemical composition using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry followed by partial least squares regression analysis

December 30, 2013
Author(s)
Thomas J. Bruno, Benjamin Kehimkar, Jamin C. Hoggard, Luke C. Marney, M. C. Billingsley, C. G. Fraga, R. E. Synovec
There is an increased need to more fully assess and control the composition of kerosene-based rocket propulsion fuels such as RP-1. In particular, it is critical to make better quantitative connections among the following three attributes: fuel performance

Thermal Conductivity of Monolayer MoS2 Obtained from Temperature-Dependent Raman Spectroscopy

December 30, 2013
Author(s)
Rusen Yan, Jeffrey R. Simpson, Simone Bertolazzi, Jacopo Brivio, Michael Watson, Xufei Wu, Andras Kis, Tengfei Luo, Angela R. Hight Walker, Huili G. Xing
Atomically thin molybdenum disulphide (MoS2) is emerging as a potential alternative to graphene due to presence of bandgap, which is particularly advantageous to optoelectronic applications. The temperature-dependent Raman spectra of exfoliated monolayer

Novel structural features in Candida albicans hyphal glucan provide a basis for differential innate immune recognition of hyphae versus yeast

December 16, 2013
Author(s)
Dan Bearden, Douglas W. Lowman, Rachel R. Greene, Michael D. Kruppa, Max Pottier, Mario Monteiro, David L. Williams
The innate immune system differentially recognizes Candida albicans yeast and hyphae. It is not clear how the innate immune system effectively discriminates between yeast and hyphal forms of C. albicans. Glucans are major components of the fungal cell wall

ENVIRONMENTAL METABOLOMICS: NMR TECHNIQUES

December 8, 2013
Author(s)
Myrna Simpson, Dan Bearden
Environmental metabolomics is a rapidly growing area of research, and over the last decade the focus has been on organism responses to various types of environmental stressors (pollutants, nutritional shifts, and global climate change, for example)

Certification of Elements in and Use of Standard Reference Material 3280 Multivitamin/Multielement Tablets

December 2, 2013
Author(s)
Gregory C. Turk, Katherine E. Sharpless, Steven J. Christopher, Danielle Cleveland, Russell D. Day, Stephen E. Long, Elizabeth A. Mackey, Anthony F. Marlow, Rick L. Paul, John R. Sieber, Rabia Oflaz, Laura J. Wood, Lee L. Yu, Rolf L. Zeisler, Stephen A. Wise, James H. Yen, E. Greene, J. Harnly, I-P Ho, Joseph M. Betz, R. Q. Thompson, Candace Jongsma
Standard Reference Material (SRM) 3280 Multivitamin/Multielement Tablets was issued by the National Institute of Standards and Technology (NIST) in 2009 and has certified and reference mass fraction values for 13 vitamins, 26 elements, and 2 carotenoids

Quantitative bottom-up proteomics depends on digestion conditions

December 2, 2013
Author(s)
Mark S. Lowenthal, Yuxue Liang, Karen W. Phinney, Stephen E. Stein
Accurate quantification is a fundamental requirement in the fields of proteomics and biomarker discovery, and for clinical diagnostic assays. To demonstrate the extent of quantitative variability in measurable peptide concentrations due to differences

Electro-Thermo-Mechanical Model for Bulk Acoustic Wave Resonators

November 30, 2013
Author(s)
Eduard Rocas, Juan C. Collado Gomez, Jordi Mateu, Nathan D. Orloff, James C. Booth, Robert Aigner
We present the electro-thermo-mechanical constitutive relations, expanded up to the third order, for a BAW resonator. The relations obtained are implemented into a circuit model, which is validated with extensive linear and nonlinear measurements. The

ToF-SIMS 3D Imaging of Native and Non-Native Species within HeLa Cells

November 26, 2013
Author(s)
Jeremy Brison, Michael A. Robinson, Danielle S. Benoit, Shinichiro Muramoto, Patrick S. Stayton, David G. Castner
In this study, a non-native chemical species, bromodeoxyuridine (BrdU), was imaged within single HeLa cells using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The z-axis corrected 3D images were reconstructed that accurately portray the

Absolute line intensities for oxirane from 1420 to 1560 cm-1

November 15, 2013
Author(s)
F K. Tchana, M. Ngom, Agnes Perrin, Jean-Marie Flaud, Walter J. Lafferty, S. A. Ndiaye, El. A. Ngum
Absolute individual line intensities of numerous transitions of the fundamental ν2 and ν10 bands of oxirane (ethylene oxide, c-C2H4O) have been measured in the 1420-1560 cm-1 region using seven high- resolution Fourier transform spectra recorded at 0.002

Absolute line intensities for the nu3 band of oxirane (C2H4O)

November 15, 2013
Author(s)
Walter J. Lafferty, Jean-Marie Flaud, Fridolin Kwabia, A. Perrin, M. Ngom
Seven Fourier transform spectra of the ν3 band of oxirane (ethylene oxide) have been recorded with different pressures and used to derive individual line intensities. These line intensities were satisfactorily fit leading to accurate transition moment

Determination of Trace Sulfur in Biodiesel and Diesel Standard Reference Materials by Isotope Dilution Sector Field Inductively Coupled Plasma Mass Spectrometry

November 14, 2013
Author(s)
Steven J. Christopher, Stephen E. Long, Renata Amais, Joaquim N?ga
A method is described for quantification of sulfur at low concentrations on the order of 10 µg g-1 in biodiesel and diesel fuels using double isotope dilution and sector field inductively coupled plasma mass spectrometry (ID-SF-ICP-MS). Closed vessel

On the Determination of Carbon by PGAA

November 10, 2013
Author(s)
Rolf L. Zeisler, Rick L. Paul, Jeffrey A. Fagan, Zsolt R?vay, Stefan S?llradl
Determination of carbon was achieved with reduction of background in prompt gamma activation analysis.

Microsensor Analyses for Trace Targets over Extended Times in a Simulated Martian Environment

November 6, 2013
Author(s)
Kurt D. Benkstein, Phillip H. Rogers, Christopher B. Montgomery, Stephen Semancik, C. Jin, Baranidharan Raman
We have studied the performance of a chemical microsensor array in a simulated Martian environment, which involved a carbon dioxide-rich background with low oxygen content (0.15 %) at low pressure and temperature to mimic the conditions at the Martian

Methods for Optimizing and Extending the Performance of Chemiresistive Gas Microsensors

November 3, 2013
Author(s)
Kurt D. Benkstein, Alexander (. Vergara Tinoco, Christopher B. Montgomery, Baranidharan Raman, Stephen Semancik
This paper briefly describes varied concepts developed and implemented to enhance the performance of gas-phase chemical microsensors. The developments are illustrated for chemiresistive (MEMS) microdevices, and involve efficient, array-based approaches to

Fluctuation Enhanced Sensing (FES) with a Nanostructured Semiconducting Metal Oxide Film for Gas Detection and Classification

October 31, 2013
Author(s)
Bulent Ayhan, Chiman Kwan, Jin Zhou, Laszlo Kish, Kurt D. Benkstein, Phillip H. Rogers, Stephen Semancik
The feasibility of fluctuation-enhanced sensing (FES) for the detection and classification of different gases by using a single microsensor has been experimentally demonstrated. A nanostructured semiconducting metal oxide film has been used as a

Achieving Climate Change Absolute Accuracy in Orbit

October 28, 2013
Author(s)
Bruce Wielicki, Joseph P. Rice
The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a metrology laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks

Connection between thermodynamics and dynamics of simple fluids in highly attractive pores

October 25, 2013
Author(s)
William P. Krekelberg, Vincent K. Shen, Daniel W. Siderius, Thomas M. Truskett, Jeffrey R. Errington
We investigate the structural and diffusive dynamics properties of a model fluid in highly-absorptive cylindrical pores. At subcritical temperatures, self diffusion displays three distinct regimes as a function of average pore density ρ: 1) a decrease in

Spectral line shapes investigation with Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy

October 23, 2013
Author(s)
A. Cygan, S. Wojtewicz, J. Domyslawska, Piotr Maslowski, Katarzyna E. Bielska, M. Piwinski, K. Stec, R.S. Trawinski, F Ozimek, C. Radzewicz, Hisashi Abe, T. Ido, Joseph T. Hodges, D Lisak, R. Ciurylo
A review of recent experiments involving a newly developed Pound-Drever-Hall-locked frequency-stabilized cavity ring-down spectroscopy (PDH-locked FS-CRDS) system is presented. By comparison to standard FS-CRDS, the PDH lock of the probe laser to the ring

Measurement, Standards, and Data Needs for CO2 Capture Materials: A Critical Review

October 21, 2013
Author(s)
Laura Espinal, Dianne L. Poster, Winnie K. Wong-Ng, Andrew J. Allen, Martin L. Green
The commercial deployment of cost-effective carbon capture technology is hindered partially by the lack of a proper suite of materials-related standards, data, and measurement methods, which would provide critical information for the systematic design of
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