An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Alexander (. Vergara Tinoco, Kurt D. Benkstein, Christopher B. Montgomery, Stephen Semancik
Performance characteristics of gas-phase microsensors will determine the ultimate utility of these devices for a wide range of chemical monitoring applications. Considerable effort has led to electronic nose devices that utilize multiple cross-selective
Yihua Y. Liu, Carlos M. Hangarter, Thomas P. Moffat
Self-terminating electrodeposition was developed for depositing ultrathin Pt overlayers on segmented electrodeposited Ni films supported on Au. The partitioned substrates provided an internal reference, namely, Pt on Au versus Pt on Ni, for every growth
Sebastian Peter, Udumula Subbarao, Sudhindra Rayaprol, Joshua Martin, Mahalingam Balasubramanian, Christos D. Malliakas, Mercouri G. Kanatzidis
The new compound Yb6.6Ir6Sn16 was obtained as single crystals in high yield from the reaction of Yb with Ir and Sn run in excess indium. Single crystal X-ray diffraction analysis shows that Yb6.6Ir6Sn16 crystallizes in the tetragonal space group P42/nmc
Scanning Electron Microscopy (SEM) and Confocal Raman Microscopy (CRM) were employed to characterize the 3D state of disperison of carbon nanotubes (CNT) in a polymer matrix. First, non-destructive subsurface imaging on CNT-polymer was conducted by charge
Kurt D. Benkstein, Christopher B. Montgomery, Stephen Semancik
For a variety of application areas, including homeland defense, environmental and health monitoring and emergency response, the detection of gas-phase chemicals is of great interest. One approach to these challenging sensing tasks is to use arrays of
Adam J. Fleisher, Bryce Bjork, Thinh Q. Bui, Kevin C. Cossel, Mitchio Okumura, Jun Ye
Quantitative measurements in chemical kinetics require unambiguous determinations of reactant, intermediate, and product concentrations on time scales faster than the reaction rate. Direct absorption spectroscopy in the mid-infrared (mid-IR) can fulfill
The table entitled Organic Analytical Reagents for the Determination of Inorganic Substances, by G. Ackermann, L. Sommer, and D. Thorburn Burns, has been revamped and considerably expanded for this edition. The many recent advancements in this area have
Xiaoyu (Sara) Yang, Pedatsur Neta, Stephen E. Stein
Electrospray ionization (ESI) tandem mass spectrometry coupled with liquid chromatography is a routine technique for identifying and quantifying compounds in complex mixtures. The identification step can be aided by matching acquired tandem mass spectra
George C. Rhoderick, Franklin R. Guenther, David L. Duewer, Jeongsoon Lee, Jin Seog Kim, Dongmin Moon, Jinbok Lee
The growing awareness of climate change/global warming and continuing concerns regarding stratospheric ozone depletion will require future measurements and standards for many compounds, in particular halocarbons that are linked to these issues. In order to
Katherine E. Sharpless, David L. Duewer, Katrice A. Lippa, Andrew L. Rukhin
Although nutraceuticals and functional foods seem to be ill-defined terms, both are often used to indicate a food that contains compounds providing benefits beyond basic nutrition, often with the expectation that these compounds are protective against
George C. Rhoderick, Franklin R. Guenther, David L. Duewer, Jeongsoon Lee, Jin S. Kim, Bradley Hall, Ray Weiss, Christina Harth, Stefan Reimann, Martin Vollmer
The growing awareness of climate change/global warming and continuing concerns regarding stratospheric ozone depletion will require future measurements and standards for many compounds, in particular halocarbons that are linked to these issues. In order to
Kurt D. Benkstein, Phillip H. Rogers, Christopher B. Montgomery, C. Jin, Baranidharan Raman, Stephen Semancik
Chemiresistive microsensor arrays are being developed and tested in a simulated Martian environment. Target analyte species include trace small molecules that may indicate current geological or, potentially, biological activity on Mars. The sensing films
Measurements of total pH, pHT, in electrochemical cells without transference are reported for 2 amino-2-hydroxymethyl 1,3-propanediol (Tris) buffers in synthetic seawater (SSW) of salinity 35 at three molality ratios of Tris to TrisHCl: 0.03:0.05, 0.04
Desorption electro-flow focusing ionization (DEFFI) mass spectrometry was used to image chemical distributions of endogenous, e.g., fatty acids, and trace exogenous compounds, e.g., explosives, narcotics and lotions, in deposited and lifted artificial
While XANES spectroscopy is an established tool for quantitative information on chemical structure and speciation, elemental concentrations are generally quantified by other methods. The edge step in XANES spectra represents the absolute amount of the
Charles J. Choi, Kurt D. Benkstein, Phillip H. Rogers, Christopher B. Montgomery, Stephen Semancik
Contact events occurring between target species and surface sites on sensing materials initiate front-end interactions and subsequent transduction processes that can yield viable signals for target detection. By offering high surface-to-volume ratios, and
Label-free optical sensors have recently emerged as a highly sensitive approach for detecting a broad range of chemical and biological analytes that include illicit drug compounds, explosives, proteins, viruses, and bacteria.To best meet such diverse
Melannie J. Bachman, Jennifer Lynch, Kristi West, Brenda Jensen
Persistent organic pollutants (POPs) are toxic man-made chemicals that bioaccumulate and biomagnify in food webs, making them a ubiquitous threat to the marine environment. Although many studies have determined concentrations of POPs in top predators, no
David A. Long, Adam J. Fleisher, Kevin O. Douglass, Stephen E. Maxwell, Katarzyna E. Bielska, Joseph T. Hodges, David F. Plusquellic
Dual-drive Mach-Zehnder modulators were utilized to produce power-leveled optical frequency combs (OFCs) from a continuous-wave laser. The resulting OFCs contained up to fifty unique frequency components and spanned more than 200 GHz. Simple changes to the
Brent A. Sperling, John Hoang, William A. Kimes, James E. Maslar, Kristen L. Steffens, Nhan V. Nguyen
Atomic layer deposition of titanium dioxide using tetrakis(dimethylamido)titanium (TDMAT) and water vapor is studied by reflection-absorption infrared spectroscopy (RAIRS) with a time resolution of 120 ms. Decomposition of the adsorbed TDMAT is observed
The solution flexibility of carbohydrates in general, and of monosaccharides in particular, influences a variety of molecular recognition and regulatory processes, from the cryoprotectant ability of glycoproteins to the relative ease with which certain
Iulia A. Sacui, Jeffrey W. Gilman, Ryan C. Nieuwendaal, Stephan J. Stranick, Henryk Szmacinski, Mehdi Jorfi, Christopher Weder, Johan Foster, Richard Olsson, Daniel Burnett
This work describes the study and characterization of native cellulose nanocrystals and nanofibrils (CNCs, CNFs), whose crystallinity, morphology, aspect ratio, and surface chemistry depend on the raw material source and hydrolysis conditions. Measurement
John Bowden, Theresa M. Cantu, Douglas M. Scheidt, Russell H. Lowers, Brian A. Nocito, Vaneica Y. Young, Louis J. Guillette
Metal deposition originating from anthropogenic activity was examined in a two-tier study using environmental samples collected from several locations at the Kennedy Space Center (KSC) and surrounding Merritt Island National Wildlife Refuge (MINWR) with
Vincent T. Sironneau, Joseph T. Hodges, Jean M. Hartmann, Julien Lamouroux
We present comparisons between measured isolated line shapes of molecular oxygen in air and those calculated, free of any adjusted parameter, using requantized Classical Molecular Dynamics Simulations (rCMDS). This work extends a previous study made for a