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Chemistry

Analytical chemistry

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  • Published Date
Displaying 1026 - 1050 of 2094

Mercury Stable Isotopes in Seabird Eggs Reflect a Gradient from Terrestrial Geogenic to Oceanic Mercury Reservoirs

April 21, 2012
Author(s)
Russell D. Day, David G. Roseneau, Sylvain Berail, Keith A. Hobson, O.F.X Donard, Stacy S. Schuur, Rebecca S. Pugh, Amanda J. Moors, Stephen E. Long, Paul R. Becker
Elevated mercury concentrations ([Hg]) were found in Alaskan seabird eggs (Uria spp.) from the coastal embayment of Norton Sound relative to insular colonies in the northern Bering Sea. Stable isotopes of Hg, carbon (C), and nitrogen (N) were measured in

Nanoscale Fullerene Compression of an Yttrium Carbide Cluster

April 13, 2012
Author(s)
Jianyuan Zhang, Fuhrer Tim, Wujun Fu, Jiechao Ge, Dan Bearden, Jerry Dallas, Duchamp James, Kenneth Walker, Hunter Champion, Hugo Azurmendi, Kim Harich, Harry C. Dorn
The encapsulation of clusters (or small molecules) in spheroidal fullerene cages provides a unique isolated environment that is important in describing their shape, dynamics, and physical properties. For the case of yttrium carbide clusters, we find that

Carbon Storage Properties of OMS-2 Manganese Oxide

April 10, 2012
Author(s)
Lan (. Li, Eric J. Cockayne, Laura Espinal, Winnie K. Wong-Ng
Manganese oxide OMS-2 material, also known as alpha-MnO2, exhibits CO2 sorption hysteresis at pressures > 7 bar. Our experiments show that the hysteretic behavior strongly depends on time, temperature and pressure. To understand the atomic structures and

Time dependent CO2 sorption hysteresis in a one-dimensional microporous octahedral molecular sieve

April 6, 2012
Author(s)
Laura Espinal, Winnie K. Wong-Ng, Andrew J. Allen, Daniel W. Siderius, Chad R. Snyder, Eric J. Cockayne, Lan (. Li, James A. Kaduk, Anais E. Espinal, Steven L. Suib, Chun Chiu
A critical challenge in the development of novel carbon capture materials with engineered porous architectures is to understand and control the phenomenon of sorption hysteresis, whereby the path to adsorption of gas molecules by the porous host differs

Determination of Perfluorinated Alkyl Acid Concentrations in Biological Standard Reference Materials

April 4, 2012
Author(s)
Jessica L. Reiner, Jennifer M. Lynch, Michele M. Schantz, Steven O'Connell, Craig M. Butt, Scott Mabury, Jeff Small, Amila De Silva, Derek Muir, Amy D. Delinsky, Mark J. Strynar, Andrew B. Lindstrom, William K. Reagen, Michelle Malinsky, Sandra Schafer, Christiaan Kwadijk
Standard Reference Materials (SRMs) are homogeneous, well-characterized materials that are used to validate measurements and improve the quality of analytical data. The National Institute of Standards and Technology (NIST) has a wide range of SRMs that

Time-Resolved Infrared Spectroscopy of an [FeFe]-Hydrogenase Model Compound

March 26, 2012
Author(s)
Edwin J. Heilweil
Naturally occurring hydrogenases catalyze the reaction of H+ to form H2 gas. To develop a hydrogen source that is not reliant on fossil fuels, synthetic [FeFe]-hydrogenase model species are being studied. These compounds have a wing-like structure with a

In Situ Raman Monitoring of Ring-Opening Copolymerizations

March 25, 2012
Author(s)
Matthew T. Hunley, Santanu S. Kundu, Peter M. Johnson, Kathryn Beers
Recent advances in enzyme, metal, and organic catalysts have enabled the development of advanced functional polymers from cyclic ester and cyclic carbonate monomers. In this work, we present an in situ technique to monitor ring-opening polymerization using

Environmental Metabolomics

March 15, 2012
Author(s)
Daniel W. Bearden
The application of metabolomics in the field of environmental science or ecology, which has developed based substantially on NMR spectroscopic approaches, is a fast paced, rapidly developing field which seems to be poised to help re-frame the discussion of

Rippling Instability of Supported Polymer Nanolines

February 21, 2012
Author(s)
Vijaya R. Tirumala, Christopher M. Stafford, Leonidas E. Ocola, Jack F. Douglas, L. Mahadevan
The swelling response of polymer line gratings supported on a rigid substrate has direct implications on their mechanical stability during pattern transfer in nanofabrication. The polymer lines, when swollen in a good solvent, undergo a rippling

Direct-comb molecular spectroscopy with accurate, resolved comb teeth over 43 THz

February 15, 2012
Author(s)
Alexander M. Zolot, Fabrizio R. Giorgetta, Esther Baumann, Jeffrey W. Nicholson, William C. Swann, Ian R. Coddington, Nathan R. Newbury
We demonstrate a dual comb spectrometer using stabilized frequency combs spanning 176 THz to 219 THz (1370 nm to 1700 nm) in the near infrared. Measurements of amplitude and phase response at each individual comb tooth span the full 43 THz, generating ~430

Measurements and Modeling Study on a High-Aromatic Diesel Fuel

January 31, 2012
Author(s)
Bret Windom, Marcia L. Huber, Thomas J. Bruno, A L. Lown, C T. Lira
The increasing cost of diesel fuel, potential for supply disruptions, and environmental concerns have resulted in a great deal of research to improve the performance and efficiency of diesel engines. This includes significant efforts in the reformulation

High-resolution, high-accuracy dual comb spectroscopy with over 40 THz bandwidth

January 20, 2012
Author(s)
Alexander M. Zolot, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann, Jeff Nicholson, Ian R. Coddington, Nathan R. Newbury
Most spectroscopic instruments directly measure optical wavelength, which is converted to frequency and calibrated against spectral features that have traditionally been measured using complicated frequency chain methods. In the past decade optical

First high-resolution analysis of the nu15, nu12, nu5, nu10 and nu2 bands of oxirane

January 15, 2012
Author(s)
Walter J. Lafferty, Jean-Marie Flaud, F. Kwabia Tchana, A. Perrin
Fourier transform spectra of Oxirane (ethylene oxide, c-C2H4O) have been recorded in the 730 cm-1 to 1560 cm-1 (6.4 to 13.7 µm) spectral region using a Bruker IFS125HR spectrometer at a resolution of 0.0019 cm-1. A total of six vibration bands, ν15, ν12

Pilot Estuarine Mesocosm Study on the Environmental Fate of Silver Nanomaterials Leached from Consumer Products

January 10, 2012
Author(s)
Danielle Cleveland, Stephen E. Long, Paul L. Pennington, Emily Cooper, Michael H. Fulton, Geoffrey I. Scott, Elijah J. Petersen, Timothy M. Brewer, Jeffrey M. Davis, Laura J. Wood
Although nanosilver consumer products (CPs) now enjoy widespread availability, little work has been done to determine the environmental fate and leaching of silver nanoparticles (AgNPs) from these products. This type of work is crucial, since the lifecycle

Predictive Gold Nanocluster Formation Controlled by Metal-Ligand Complexes

January 9, 2012
Author(s)
John M. Pettibone, Jeffrey W. Hudgens
The formation of ligand-protected transition metal nanoclusters in size-selective syntheses is driven by the inherent properties of the protecting ligands. We have previously reported the selective, monodisperse product formation of phosphine protected Au
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