Open Access. Powered by Scholars. Published by Universities.®

Biochemistry, Biophysics, and Structural Biology Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 14 of 14

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

High Resolution Time-Of-Flight Mass Spectrometry Fingerprinting Of Metabolites From Cecum And Distal Colon Contents Of Rats Fed Resistant Starch, Timothy James Anderson, Roger W. Jones, Yongfeng Ai, Robert S. Houk, Jay-Lin Jane, Yinsheng Zhao, Diane F. Birt, John Frederick Mcclelland Jan 2014

High Resolution Time-Of-Flight Mass Spectrometry Fingerprinting Of Metabolites From Cecum And Distal Colon Contents Of Rats Fed Resistant Starch, Timothy James Anderson, Roger W. Jones, Yongfeng Ai, Robert S. Houk, Jay-Lin Jane, Yinsheng Zhao, Diane F. Birt, John Frederick Mcclelland

Ames Laboratory Publications

Time-of-flight mass spectrometry along with statistical analysis was utilized to study metabolic profiles among rats fed resistant starch (RS) diets. Fischer 344 rats were fed four starch diets consisting of 55 % (w/w, dbs) starch. A control starch diet consisting of corn starch was compared against three RS diets. The RS diets were high-amylose corn starch (HA7), HA7 chemically modified with octenyl succinic anhydride, and stearic-acid-complexed HA7 starch. A subgroup received antibiotic treatment to determine if perturbations in the gut microbiome were long lasting. A second subgroup was treated with azoxymethane (AOM), a carcinogen. At the end of the 8-week ...


Analysis Of Writing Inks On Paper Using Direct Analysis In Real Time Mass Spectrometry, Roger W. Jones, John Frederick Mcclelland Sep 2013

Analysis Of Writing Inks On Paper Using Direct Analysis In Real Time Mass Spectrometry, Roger W. Jones, John Frederick Mcclelland

Ames Laboratory Publications

Ink analysis is central to questioned document examination. We applied direct analysis in real time mass spectrometry (DART MS) to ballpoint, gel, and fluid writing ink analysis. DART MS acquires the mass spectrum of an ink while it is still on a document without altering the appearance of the document. Spectra were acquired from ink on a variety of papers, and the spectrum of the blank paper could be subtracted out to produce a cleanly isolated ink spectrum in most cases. Only certain heavy or heavily processed papers interfered. The time since an ink is written on paper has a ...


Real-Time Monitoring Of The Mechanical Properties Of A Soy Protein And Rubber Polymer During Its Production Using Transient Infrared Spectroscopy, Jeffrey J. Sweterlitsch, Perminus Mungara, Roger W. Jones, Jay-Lin Jane, John Frederick Mcclelland Jan 2013

Real-Time Monitoring Of The Mechanical Properties Of A Soy Protein And Rubber Polymer During Its Production Using Transient Infrared Spectroscopy, Jeffrey J. Sweterlitsch, Perminus Mungara, Roger W. Jones, Jay-Lin Jane, John Frederick Mcclelland

Ames Laboratory Publications

Soy protein-based polymers offer promising performance properties, but their characteristics are sensitively dependent on production conditions, so on-line monitoring could help provide the needed control during production. Mid-infrared spectroscopy combined with partial least squares offer the needed analysis, but the opacity of many materials in the mid-infrared limits its conventional application. Transient infrared spectroscopy is a method of acquiring mid-infrared spectra from moving streams in real time that avoids the opacity problem. We apply transient infrared spectroscopy to a polymer of soy protein and polyisoprene-graft-maleic anhydride– modified natural rubber during its compounding extrusion to measure tensile strength and Young’s ...


Molecular Analysis Of Primary Vapor And Char Products During Stepwise Pyrolysis Of Poplar Biomass, Roger W. Jones, Tonu Reinot, John Frederick Mcclelland Jan 2010

Molecular Analysis Of Primary Vapor And Char Products During Stepwise Pyrolysis Of Poplar Biomass, Roger W. Jones, Tonu Reinot, John Frederick Mcclelland

Ames Laboratory Publications

Pyrolysis of biomass produces both pyrolysis oil and solid char. In this study, poplar has been pyrolyzed in a stepwise fashion over a series of temperatures from 200 to 500 °C, and both the primary products contributing to pyrolysis oil and the changes in the pyrolyzing poplar surface leading toward char have been characterized at each step. The primary products were identified by direct analysis in real time (DART) mass spectrometry, and the changes in the poplar surface were monitored using Fourier transform infrared (FTIR) photoacoustic spectroscopy, with a sampling depth of a few micrometers. The primary products from pyrolyzing ...


Differentiating Writing Inks Using Direct Analysis In Real Time Mass Spectrometry, Roger W. Jones, Robert B. Cody, John Frederick Mcclelland Jul 2006

Differentiating Writing Inks Using Direct Analysis In Real Time Mass Spectrometry, Roger W. Jones, Robert B. Cody, John Frederick Mcclelland

Ames Laboratory Publications

Writing ink analysis is used in establishing document authenticity and the sources and relative ages of written entries. Most analytical methods require removing samples or visibly altering the document. Nondestructive, in situ analysis of writing inks on paper without visible alteration is possible using mass spectrometry with a new ion source called Direct Analysis in Real Time. Forty-three different black and blue ballpoint, black fluid, and black gel inks were examined. Both dyes and persistent but thermally labile components of the inks contribute to the mass spectra, principally as protonated molecules [M1H]1. Numerous ink components were identified from the ...


Observation Of Large Photoacoustic Signal Phase Changes During A Diffusion Process, Stanley J. Bajic, Roger W. Jones, John F. Mcclelland Nov 2005

Observation Of Large Photoacoustic Signal Phase Changes During A Diffusion Process, Stanley J. Bajic, Roger W. Jones, John F. Mcclelland

Ames Laboratory Publications

The phase of the photoacoustic signal is known to be a sensitive and accurate means to investigate, both qualitatively and quantitatively, static multilayer heterogeneous systems. According to theory, the maximum phase delay for a very weakly absorbing homogeneous sample should be within 45° of a very strongly absorbing sample, while for heterogeneous samples the phase delay can be greater than 45°. Here we report the observation of photoacoustic phase delays greater than 350° by extending the use of step-scan phase modulation photoacoustic spectroscopy to study a non-repetitive dynamic system in situ, in real time. These large phase delays correspond to ...


Ftir Photoacoustic Spectroscopy Applied To The Curing And Aging Of Composites, Roger W. Jones, Jeffrey J. Sweterlitsch, Anthony J. Wagner, John F. Mcclelland, David K. Hsu, Daniel L. Polis, Marjorie F. Sovinski Jan 2005

Ftir Photoacoustic Spectroscopy Applied To The Curing And Aging Of Composites, Roger W. Jones, Jeffrey J. Sweterlitsch, Anthony J. Wagner, John F. Mcclelland, David K. Hsu, Daniel L. Polis, Marjorie F. Sovinski

Ames Laboratory Publications

Fourier-transform infrared photoacoustic spectroscopy has been applied to carbonfiber composites to test whether bulk physical properties of the composites could be determined using the near-surface-sensitive photoacoustic approach. Both the cure levels of carbon fiber/cyanate ester composites and the interlaminar shear strengths of artificially aged carbon fiber/epoxy composites were successfully measured. Standard errors of cross validation were 3.46% cure for a sample set ranging from 8% to 95% cured and 1.60 MPa for aged samples with strengths ranging from 22 to 77 MPa.


Prediction Of Interlaminar Shear Strength Of A Thermally Aged Carbon/Epoxy Composite Material By Fourier Transform Infrared Photoacoustic Spectroscopy, Jeffrey J. Sweterlitsch, Roger W. Jones, David K. Hsu, John F. Mcclelland Dec 2004

Prediction Of Interlaminar Shear Strength Of A Thermally Aged Carbon/Epoxy Composite Material By Fourier Transform Infrared Photoacoustic Spectroscopy, Jeffrey J. Sweterlitsch, Roger W. Jones, David K. Hsu, John F. Mcclelland

Ames Laboratory Publications

Photoacoustic spectroscopy was used to predict the interlaminar shear strength of a carbon/epoxy composite. Samples were artificially aged by exposing the samples to elevated temperatures in an air environment. Short-beam shear tests were performed to determine mechanically the interlaminar shear strength of the samples. Photoacoustic spectra of the samples were also collected and compared to mechanical data. Chemometrics were performed on the spectral and mechanical data, and a good correlation was found between the near surface chemistry of the composite and overall mechanical integrity.


Practical Analysis Of Polymers With Depth Varying Compositions Using Fourier Transform Infrared Photoacoustic Spectroscopy (Plenary), John F. Mcclelland, Roger W. Jones, Siquan Luo Jan 2003

Practical Analysis Of Polymers With Depth Varying Compositions Using Fourier Transform Infrared Photoacoustic Spectroscopy (Plenary), John F. Mcclelland, Roger W. Jones, Siquan Luo

Ames Laboratory Publications

Fourier transform infrared photoacoustic spectroscopy can be used as a nondestructive method to probe the molecular composition of materials as a function of depth into the sample. This is done by varying the thickness of the surface layer being analyzed, which can be as great as some tens of micrometers, depending on optical and thermal properties.Computational methods are described to process photoacoustic amplitude and phase spectra for both semiquantitative and quantitative depth analyses. These methods are demonstrated on layered and gradient samples.


Quantitative Depth Profiling Using Saturation-Equalized Photoacoustic Spectra, Roger W. Jones, John F. Mcclelland Apr 2002

Quantitative Depth Profiling Using Saturation-Equalized Photoacoustic Spectra, Roger W. Jones, John F. Mcclelland

Ames Laboratory Publications

Depth profiling using photoacoustic spectra taken at multiple scanning speeds or modulation frequencies is normally impaired by the increase in spectral saturation that occurs with decreasing speed or frequency. Photothermal depth profiling in general is also impeded by the ill conditioned nature of the mathematical problem of determining a depth profile from photothermal data. This paper describes a method for reducing the saturation level in low-speed or low-frequency spectra to the level at high speed or frequency so that all spectra have the same saturation. The conversion method requires only magnitude spectra, so it is applicable to both conventional and ...


Phase References And Cell Effects In Photoacoustic Spectroscopy, Roger W. Jones, John F. Mcclelland Oct 2001

Phase References And Cell Effects In Photoacoustic Spectroscopy, Roger W. Jones, John F. Mcclelland

Ames Laboratory Publications

In Fourier transform infrared (FT-IR) photoacoustic spectroscopy, advanced scanning and data-handling techniques have placed increasing emphasis on the phase of the photoacoustic signal. Unfortunately, there is no agreement on the best material to use as a phase reference. We have examined the frequency dependence of the signal from several candidate phase references and found that cell effects dominate the absolute phases and magnitudes observed. The absolute phase is exceptionally fast at low frequencies and exceptionally slow at high frequencies because of the cell effects. Accordingly, details such as sample position must be scrupulously controlled to achieve accurate, reproducible results. Because ...


Ftir Photoacoustic Spectroscopy Of Diesel Lubricant Oils Containing Particulate Matter, John F. Mcclelland, Roger W. Jones Jan 2001

Ftir Photoacoustic Spectroscopy Of Diesel Lubricant Oils Containing Particulate Matter, John F. Mcclelland, Roger W. Jones

Ames Laboratory Publications

Monitoring of engine lubricants in service is important for evaluating engine conditions as well as the performance of new and existing lubricant formulations. Fourier-transform infrared (FTIR) spectroscopy has previously been demonstrated as an effective technique for analyzing lubricant condition, but used oils laden with soot and other particulate matter are difficult to analyze with common FTIR sampling techniques because of the strong lightabsorption and scattering by the particulates. FTIR photoacoustic spectroscopy is examined here as an alternative sampling technique for analyzing particulate-laden oils. Diesel-engine oils spiked with carbon black and phorone are analyzed quantitatively for particulate and carbonyl-species contentusing FTIR ...


Quantitative Depth Profiling Of Layered Samples Using Phase-Modulation Ft-Ir Photoacoustic Spectroscopy, Roger W. Jones, John F. Mcclelland Oct 1996

Quantitative Depth Profiling Of Layered Samples Using Phase-Modulation Ft-Ir Photoacoustic Spectroscopy, Roger W. Jones, John F. Mcclelland

Ames Laboratory Publications

In phase-modulation FT-IR spectroscopy, all wavelengths in a spectrum are modulated at the same frequency and in phase. This factor makes the use of photoacoustic phase data for depth profiling samples much easier in phase modulation than in rapid scan. A method to quantitatively measure layer thickness by using the phase of a substrate spectrum peak is demonstrated with a series of samples consisting of thin polymer films on substrates. Additions to the basic method are demonstrated that extend its application to cases where the substrate peak is overlapped by a spectrum peak of the surface film. A linear relationship ...


Analysis Of Underground Storage Tank Waste Simulants By Fourier Transform Infrared Photoacoustic Spectroscopy, Stanley J. Bajic, Siquan Luo, Roger W. Jones, John F. Mcclelland Jul 1995

Analysis Of Underground Storage Tank Waste Simulants By Fourier Transform Infrared Photoacoustic Spectroscopy, Stanley J. Bajic, Siquan Luo, Roger W. Jones, John F. Mcclelland

Ames Laboratory Publications

Underground storage tank waste sludge from nuclear fuel processes is difficult to analyze because of the extreme heterogeneity, chemical reactivity, and radioactivity of the waste. Conventional methods of analysis typically require extensive sample handling procedures either to thin the sample or to separate components prior to analysis. These procedures are time consuming, require radiation containment cells, and increase the risk of radiation exposure to lab personnel as a result of the extensive handling. In this paper a method utilizing Fourier transform infrared photoacoustic spectroscopy to analyze hazardous underground storage tank waste with a minimal amount of sample and sample handling ...