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Search Publications by: William E. Wallace (Fed)

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Displaying 26 - 50 of 217

Pairwise Alignment of Chromatograms using a Fisher-Rao Metric

September 2, 2014
Author(s)
William E. Wallace, Anuj Srivastava, Kelly H. Telu, Yamil Simon
A new approach to aligning chromatograms is introduced and applied to examples of metabolite identification by liquid chromatography mass spectrometry (LC MS). A square root representation of the chromatogram’s derivative coupled with a Fisher Rao

Stochastic Regression Modeling of Chemical Spectra

August 14, 2014
Author(s)
Anthony J. Kearsley, William E. Wallace, Yutheeka Gadhyan
A stochastic regression method has been developed that decomposes chemical spectra into separate contributions from signal and from noise. The numerical results of regressing in this way on sample spectra are presented. The results suggest that this

Metabolite Profiling of a NIST Standard Reference Material for Human Plasma (SRM 1950) – GC/MS, LC/MS, NMR and Clinical Laboratory Analyses, Libraries and Web-based resources

October 22, 2013
Author(s)
Yamil Simon, Mark S. Lowenthal, Lisa E. Kilpatrick, Maureen L. Sampson, Kelly H. Telu, Paul A. Rudnick, William G. Mallard, Daniel W. Bearden, Tracey B. Schock, Dmitrii V. Tchekhovskoi, Niksa Blonder, Xinjian Yan, Yuxue Liang, Yufang Zheng, William E. Wallace, Pedatsur Neta, Karen W. Phinney, Alan T. Remaley, Stephen E. Stein
Recent progress in metabolomics and the development of increasingly sensitive analytical techniques have renewed interest in global profiling, i.e., semi-quantitative monitoring of all chemical constituents of biological fluids. In this work, we have

Automated Data Processing and Quantification in Polymer Mass Spectrometry

December 1, 2011
Author(s)
Till Gruendling, Christopher Barner-Kowollik, William E. Wallace, Charles M. Guttman, Anthony J. Kearsley
An overview is given of some new techniques in quantitative composition and molecular mass distribution measurement of synthetic polymers by mass spectrometry. New concepts in data analysis, including peak picking and integration, are also described.

CONTINUOUS FLOW ENZYME-CATALYZED POLYMERIZATION IN A MICROREACTOR

March 25, 2011
Author(s)
Santanu S. Kundu, Atul S. Bhangale, William E. Wallace, Kathleen M. Flynn, Charles M. Guttman, Richard Gross, Kathryn L. Beers
Enzymes immobilized on solid supports are increasingly used for chemical transformation because the process is greener and sustainable. Here we use microreactors to study enzyme catalyzed ring opening polymerization of -caprolactone to polycaprolactone. A

Molecular Mass Distribution Measurement by Mass Spectrometry

May 19, 2010
Author(s)
William E. Wallace, Charles M. Guttman
This NIST Recommended Practice Guide presents a method using mass spectrometry to make a quantitative determination of the molecular mass distribution of narrow polydispersity synthetic molecular materials. The main obstacle for converting an oligomer

Reactive MALDI Mass Spectrometry of Saturated Hydrocarbons: A Theoretical Study

May 1, 2010
Author(s)
William E. Wallace, Lewandowski Hans, Meier J. Robert
Recently it has been shown that the cobaltocenium cation, prepared by the laser ablation of a CoCp(CO)2/fullerene matrix, may react with alkanes and polyethylenes in the gas phase via a dehydrogenation reaction to produce [Co(Cp)2(alkadiene)]+ ions without

IMMOBILIZED ENZYME CATALYZED POLYMERIZATION REACTIONS IN MICROREACTORS

January 1, 2010
Author(s)
Santanu S. Kundu, Atul Bhangale, William E. Wallace, Kathleen M. Flynn, Richard Gross, Kathryn L. Beers
Application of microreactor technologies enable improved safety, selectivity and yield in a range of chemical reactions in addition to new measurement methods that are often faster, cheaper and more accurate than traditional methods. In this study we have

IMPACT OF IMMOBILIZATION SUPPORTS FOR POLYESTERS SYNTHESIS ACTIVITY OF CANDIDA ANTARTICA LIPASE B

January 1, 2010
Author(s)
Atul Bhangale, Santanu S. Kundu, Wenchun Xie, William E. Wallace, Kathleen M. Flynn, Kathryn L. Beers, Richard Gross
Epoxy functionalized supports are known to be suitable for industrial-scale immobilization of enzymes for biocatalysis. However, chemistry across these epoxy groups is known to affect the catalytic performance of the enzymes.In order to achieve a balance

PEG-HYDROGELS: SYNTHESIS, CHARACTERIZATION, AND CELL ENCAPSULATION

September 15, 2009
Author(s)
Sheng Lin-Gibson, Kaushik Chatterjee, James A. Cooper, William E. Wallace, Matthew Becker, Carl G. Simon Jr., Ferenc Horkay
A simple reaction to prepare controlled molecular mass (MM) poly(ethylene glycol) dimethacrylates (PEGDMs) of high purity and low polydispersity is outlined. PEGDMs were photo-polymerized to form hydrogels with and without bioactive moieties. The structure