A5056860203- Advanced Chemical Sensor Technologies
- Analytical Chemistry and Sensors
- Analytical Chemistry and Chromatography
- Acoustic Wave Resonator Technologies
- Microfluidic and Capillary Electrophoresis Applications
- Mechanical and Optical Resonators
- Gas Sensing Nanomaterials and Sensors
- Photonic and Optical Devices
- Mass Spectrometry Techniques and Applications
- Molecular Junctions and Nanostructures
- Innovative Microfluidic and Catalytic Techniques Innovation
- Advanced MEMS and NEMS Technologies
- Advanced Fiber Optic Sensors
- Gold and Silver Nanoparticles Synthesis and Applications
- Indoor Air Quality and Microbial Exposure
- Chemical Safety and Risk Management
- Thermal and Kinetic Analysis
- Synthesis and properties of polymers
- Analytical chemistry methods development
- Polymer crystallization and properties
- Air Quality Monitoring and Forecasting
- Carbon Nanotubes in Composites
- Electrochemical Analysis and Applications
- Liquid Crystal Research Advancements
- Synthesis and Characterization of Heterocyclic Compounds
National Center for Biotechnology Information
2024
National Institutes of Health
2024
University of Michigan–Ann Arbor
2011-2020
ETH Zurich
2007
Center for Environmental Health
1980-2004
Division of Chemistry
2004
Sandia National Laboratories California
2001
Pacific Northwest National Laboratory
2000
Environmental Molecular Sciences Laboratory
2000
University of Iowa
1998-1999
The National Center for Biotechnology Information (NCBI) provides online information resources biology, including the GenBank® nucleic acid sequence repository and PubMed® of citations abstracts published in life science journals. NCBI search retrieval operations most these data from 31 distinct repositories knowledgebases. E-utilities serve as programming interface these. Resources receiving significant updates past year include PubMed, PubMed Central, Bookshelf, NIH Comparative Genomics...
The fabrication, assembly, and initial testing of a hybrid microfabricated gas chromatograph (µGC) is described. µGC incorporates capabilities for on-board calibration, sample preconcentration focused thermal desorption, temperature-programmed separations, "spectral" detection with an integrated array microsensors, designed rapid determinations complex mixtures environmental contaminants at trace concentrations. Ambient air used as the carrier to avoid need supplies. microsystem plumbed...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOptimal Coating Selection for the Analysis of Organic Vapor Mixtures with Polymer-Coated Surface Acoustic Wave Sensor ArraysEdward T. Zellers, Stuart A. Batterman, Mingwei. Han, and Samuel J. PatrashCite this: Anal. Chem. 1995, 67, 6, 1092–1106Publication Date (Print):March 15, 1995Publication History Published online1 May 2002Published inissue 15 March...
Etude des caracteristiques de capteurs qui utilisent la propagation ondes Lamb sur membranes composites Si-ZnO
The design, fabrication, and characterization of a multiple-stage Si microfabricated preconcentrator-focuser (/spl mu/PCF) for micro gas chromatography mu/GC) system that can provide real-time quantification identification complex organic vapor mixtures are presented. /spl mu/PCF consists microheater loaded with Carbopack B, X, Carboxen 1000 carbon adsorbent granules, micromachined cover plate. Deep reactive ion etching is utilized to produce mechanically robust fluidic interconnection...
The synthesis and testing of two gold-thiolate monolayer-protected (nano)clusters as interfacial layers on a dual-chemiresistor vapor sensor array are described. Responses (changes in dc resistance) to each 11 organic solvent vapors rapid, reversible, linear with concentration at low concentrations, becoming sublinear higher concentrations. Limits detection (LODs) range from 0.1 24 parts per million vary inversely pressure. When configured GC detector used analyze 0.5-L preconcentrated...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharacterization of polymeric surface acoustic wave sensor coatings and semiempirical models responses to organic vaporsSamuel J. Patrash Edward T. ZellersCite this: Anal. Chem. 1993, 65, 15, 2055–2066Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Published inissue 1 August 1993https://doi.org/10.1021/ac00063a021RIGHTS & PERMISSIONSArticle Views399Altmetric-Citations99LEARN ABOUT THESE METRICSArticle Views are...
An investigation of the modulation charge transport through thin films n-octanethiolate monolayer-protected gold nanoparticles (MPN) induced by sorption organic vapors is presented. A model derived that allows predictions MPN-coated chemiresistor (CR) responses from vapor−film partition coefficients, and analyte densities dielectric constants. Calibrations with 28 compounds collected an array CRs a parallel thickness-shear-mode resonator are used to verify assumptions inherent in assess its...
A complete field-deployable microfabricated gas chromatograph (μGC) is described, and its adaptation to the analysis of low- subparts-per-billion (ppb) concentrations trichloroethylene (TCE) vapors in complex mixtures demonstrated through laboratory testing. The specific application being addressed concerns problem indoor air contamination by TCE vapor intrusion. μGC prototype employs a focuser, dual separation columns, microsensor array. These are interfaced nonmicrofabricated front-end...
A prototype microfabricated gas chromatograph (μGC) adapted specifically for the rapid determination of selected gas-phase marker compounds explosive 2,4,6-trinitrotoluene (TNT) at sub-parts-per-billion (<ppb) concentrations in complex mixtures is described. Si-microfabricated focuser, separation column, and sensor array components are integrated with a high-volume sampler conventional construction to reduce analysis time limit detection (LOD). The primary markers as target analytes were...
The design, fabrication, and testing of a preconcentrator-focuser (PCF), consisting thick micromachined Si heater packed with small quantity granular adsorbent material are described. PCF is developed to capture concentrate vapors for subsequent focused thermal desorption analysis in micro gas chromatograph. microheater contains an array high-aspect-ratio, etched-Si heating elements, 520 μm (h)×50 (w)×3000 (l), bounded by annulus thermally isolated from the remaining substrate air gap. This...
A prototype portable gas chromatograph that combines a multiadsorbent preconcentrator/focuser, tandem-column separation stage with individual column temperature control and junction point pressure modulation, detector consisting of an integrated array polymer-coated surface acoustic wave microsensors is described. Using scheduled first-column stop-flow intervals independent programming the two columns, it possible to adjust retention eluting analyte vapors maximize vapor recognition...
A comprehensive analysis of vapor recognition as a function the number sensors in vapor−sensor array is presented. Responses to 16 organic vapors collected from six polymer-coated surface acoustic wave (SAW) were used Monte Carlo simulations coupled with pattern analyses derive statistical estimates rates (≤6), polymer sensor coatings employed, and concentration being analyzed. Results indicate that few two can recognize individual set possibilities <6% average error, long concentrations are...
The development and testing of a miniature dual-adsorbent preconcentrator for microsensor-based analytical system designed to determine complex volatile organic chemical (VOC) mixtures encountered in indoor working environments at low part-per-billion levels is described. Candidate adsorbents were screened thermal-desorption bandwidth breakthrough volume against 20 vapors subsets thereof as function several relevant variables. A glass capillary (1.1 mm i.d.) packed with 3.4 mg Carbopack X...
A single-phase synthesis of thiolate monolayer-protected gold clusters (MPCs) is described. This method avoids the problem persistent ionic contamination from residual phase-transfer catalyst while retaining versatility associated with commonly used two-phase Brust synthesis. MPCs having alkyl, diphenylacetylene, ether, amide, or ester functionalities were prepared by this and characterized via 1H NMR, FT-IR, UV−vis absorption spectroscopy, TGA, STM, TEM. Comparisons products synthesized...
The laboratory characterization of a novel, second-generation portable gas chromatograph (GC) prototype designed for trace-level determinations complex mixtures volatile organic compounds (VOC) is described. instrument incorporates small, multi-stage adsorbent preconcentrator/injector (PCI), two series-coupled separation columns with fast, independent temperature-programming capabilities and junction-point pressure/flow control, detector consisting an array microfabricated chemiresistor (CR)...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSilicon-directed Baeyer-Villiger reactions. Stereospecific synthesis of olefinic acids and estersPaul F. Hudrlik, Anne M. Gopalpur Nagendrappa, Tilahun Yimenu, Edward T. Zellers, Evelyn ChinCite this: J. Am. Chem. Soc. 1980, 102, 22, 6894–6896Publication Date (Print):October 15, 1980Publication History Published online1 May 2002Published inissue 15 October...
We describe a belt-mountable prototype instrument containing gas chromatographic microsystem (μGC) and demonstrate its capability for near-real-time recognition quantification of volatile organic compounds (VOCs) in moderately complex mixtures at concentrations encountered industrial workplace environments. The μGC comprises three discrete, Si/Pyrex microfabricated chips: dual-adsorbent micropreconcentrator–focuser VOC capture injection; wall-coated microcolumn with thin-metal heaters...
The applicability and performance of linear solvation energy relationships (LSERs) as models responses from polymer-coated acoustic-wave vapor sensors are critically examined. Criteria for the use these thermodynamic with thickness-shear-mode resonator (TSMR) surface-acoustic-wave (SAW) clarified. Published partition coefficient values derived gas−liquid chromatography (GLC) found to be consistently lower than those obtained gravimetrically, in accordance previous reports, suggesting that...
The influences of temperature and atmospheric humidity on the performance an array eight polymer-coated 158-MHz surface acoustic wave vapor sensors were investigated. Sensitivities to seven organic vapors examined all exhibited negative Arrhenius dependencies, with responses increasing by factors 1.5−4.4 going from 38 18 °C. magnitudes effects, while generally similar, differed sufficiently among certain sensor−vapor combinations cause marked changes in response patterns. In addition, it was...
A small multi-adsorbent preconcentration/focusing module for a portable GC with microsensor-array detector designed to determine complex mixtures of volatile and semi-volatile organic compounds encountered in indoor working environments is described. Candidate adsorbents were assessed on the basis analyte thermal-desorption bandwidth efficiency, chromatographic peak shape, breakthrough volume against ranging over four orders magnitude vapor pressure. capillary packed just 12.3 mg adsorbent...
The “limit of recognition” (LOR) has been defined as the minimum concentration at which reliable individual vapor recognition can be achieved with a multisensor array, and methodology for determining LORs vapors probabilistically on basis sensor array response patterns reported. This article explores problems defining evaluating mixtures in terms absolute relative component concentrations, where mixture must discriminated from those subset possible lower-order mixtures. Monte Carlo...