677 Matching Results

Search Results

Advanced search parameters have been applied.

Distinguishability of Biological Material Using Ultraviolet Multi-Spectral Fluorescence

Description: Recent interest in the detection and analysis of biological samples by spectroscopic methods has led to questions concerning the degree of distinguishability and biological variability of the ultraviolet (W) fluorescent spectra from such complex samples. We show that the degree of distinguishability of such spectra is readily determined numerically.
Date: October 14, 1998
Creator: Gray, P.C.; Heinen, R.J.; Rigdon, L.D.; Rosenthal, S.E.; Shokair, I.R.; Siragusa, G.R. et al.
Partner: UNT Libraries Government Documents Department

Biomolecular Materials. Report of the January 13-15, 2002 Workshop

Description: Twenty-two scientists from around the nation and the world met to discuss the way that the molecules, structures, processes and concepts of the biological world could be used or mimicked in designing novel materials, processes or devices of potential practical significance. The emphasis was on basic research, although the long-term goal is, in addition to increased knowledge, the development of applications to further the mission of the Department of Energy.
Date: January 15, 2002
Creator: Alper, M. D. & Stupp, S. I.
Partner: UNT Libraries Government Documents Department

ORGANIC GEOCHEMICAL STUDIES. I. MOLECULAR CRITERIA FOR HYDROCARBONGENESIS

Description: In recent years the search for life-forms at the earliest periods of geological time has been continued not only at the morphological level but also at the molecular level. This has been possible as a result of the increase in the biochemical knowledge and with the advent of analytical techniques that are capable of describing the intimate molecular architecture of individual molecules in acute detail. The fundamental premises upon which this organic geochemical approach rest are the following: that certain molecules, possessing a characteristic structural skeleton, show a reasonable stability to degradation over long periods of geological time; that their structural specificity can be understood in terms of known biosynthetic sequences; and that their formation by any non-biological means is of negligible probability. In this manuscript it is proposed to critically re-examine these premises and to establish criteria whereby one can differentiate molecules derived from biological systems from those that have their origin in non-biological processes. The importance of establishing such criteria lies in the significance these criteria have in determining whether life exists, or has existed, on other planets. Within the very near future it may be possible to provide an initial answer to this question when the first lunar samples are returned to the earth for analysis.
Date: September 22, 1967
Creator: McCarthy, Eugene D. & Calvin, Kevin
Partner: UNT Libraries Government Documents Department

Chemical Evolution and the Origin of Life

Description: A discussion is presented of the elements, or at least most of the elements, that are usually thought of as required and characteristic of living materials. A continuous evolutionary process is conceived, beginning with a bare earth and leading to the random formation of more or less complex molecules from simple ones, and gradually, by the processes of random variation, autocatalysis, and selection, to more complex systems and the ordered array of desoxynucleic acid molecules which are the units that carry the continuity and order of present-day living systems.
Date: August 11, 1955
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

QUANTUM CONVERSION IN PHOTOSYNTHESIS

Description: A new suggestion is made based on model work associated with similar measurements on the biological material itself. The primary quantum conversion act is an ionization occurring in a charge transfer complex. This is what it amounts to in chemical terms. But this process cannot occur in isolated charge transfer molecules in solution because the products cannot escape from each other. The primary quantum conversion as it occurs in modern photosynthesis can only take place in a laminated structure where the electrons and holes can escape from each other by electron migration and not by atomic migrations. This is the essential feature introduced here which differs from all the previous notions of how quantum conversion occurs in chemistry or biology.
Date: January 1, 1961
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

BioWatch in a Box

Description: BioWatch, the U.S. Department of Homeland Security (DHS) environmental monitoring program, has been successfully operating in many of the nation's urban centers since early 2003. This early warning environmental monitoring system can detect trace amounts of biological materials in the air, and has been used to provide information to assist public health experts determine whether detected materials are due to an intentional release (bioterrorism incident) or due to minute quantities that occur naturally in the environment. BioWatch information enables federal, state, and local officials to more quickly determine appropriate emergency response, medical care and consequence management.
Date: February 1, 2006
Creator: McBride, M T; Dzentis, J M & Meyer, R M
Partner: UNT Libraries Government Documents Department

Biomanufacturing : a state of the technology review.

Description: Biomanufacturing has the potential to be one of the defining technologies in the upcoming century. Research, development, and applications in the fields of biotechnology, bioengineering, biodetection, biomaterials, biocomputation and bioenergy will have dramatic impact on both the products we are able to create, and the ways in which we create them. In this report, we examine current research trends in biotechnology, identify key areas where biomanufacturing will likely be a major contributing field, and report on recent developments and barriers to progress in key areas.
Date: September 1, 2003
Creator: Morgan, Sarah Anne (East Texas Baptist University, Marshall, TX); Colon, Silverio C. (Arizona State University, Tempe, AZ); Myers, Ramona Lynn; Emerson, John Allen & Ruffner, Judith Alison
Partner: UNT Libraries Government Documents Department

Indoor Sampler Siting

Description: Contaminant releases in or near a building can lead to significant human exposures unless prompt response is taken. U.S. Federal and local agencies are implementing programs to place air-monitoring samplers in buildings to quickly detect biological agents. We describe a probabilistic algorithm for siting samplers in order to detect accidental or intentional releases of biological material. The algorithm maximizes the probability of detecting a release from among a suite of realistic scenarios. The scenarios may differ in any unknown, for example the release size or location, weather, mode of building operation, etc. The algorithm also can optimize sampler placement in the face of modeling uncertainties, for example the airflow leakage characteristics of the building, and the detection capabilities of the samplers. In an illustrative example, we apply the algorithm to a hypothetical 24-room commercial building, finding optimal networks for a variety of assumed sampler types and performance characteristics. We also discuss extensions of this work for detecting ambient pollutants in buildings, and for understanding building-wide airflow, pollutant dispersion, and exposures.
Date: March 1, 2009
Creator: Sohn, Michael D. & Lorenzetti, David M.
Partner: UNT Libraries Government Documents Department

Structural analysis of flexible proteins in solution by SmallAngle X-ray Scattering combined with crystallography

Description: In the last few years, SAXS of biological materials has been rapidly evolving and promises to move structural analysis to a new level. Recent innovations in SAXS data analysis allow ab initio shape predictions of proteins in solution. Furthermore, experimental scattering data can be compared to calculated scattering curves from the growing data base of solved structures and also identify aggregation and unfolded proteins. Combining SAXS results with atomic resolution structures enables detailed characterizations in solution of mass, radius, conformations, assembly, and shape changes associated with protein folding and functions. SAXS can efficiently reveal the spatial organization of protein domains, including domains missing from or disordered in known crystal structures, and establish cofactor or substrate-induced conformational changes. For flexible domains or unstructured regions that are not amenable for study by many other structural techniques, SAXS provides a unique technology. Here, we present SAXS shape predictions for PCNA that accurately predict a trimeric ring assembly and for a full-length DNA repair glycosylase with a large unstructured region. These new results in combination with illustrative published data show how SAXS combined with high resolution crystal structures efficiently establishes architectures, assemblies, conformations, and unstructured regions for proteins and protein complexes in solution.
Date: May 25, 2006
Creator: Tsutakawa, Susan E.; Hura, Greg L.; Frankel, Ken A.; Cooper,Priscilla K. & Tainer, John A.
Partner: UNT Libraries Government Documents Department

A New Standard for Multidisciplinary Health and Safety Technicians

Description: The purpose of this standard (ANSI 13.62)--''Training and Qualification of Health and Safety Technicians''--is to provide a means for the development of technicians with necessary skills in industrial hygiene, industrial safety, radiological safety, fire protection, and other health and safety areas specific to a given work site and its hazards. These individuals should be qualified to handle their roles and responsibilities competently in a variety of safety areas. The standard presented here is intended for individuals who develop, revise, implement, manage, or provide oversight of training for health and safety technicians. The standard is not intended to address the training or qualification of safety professionals (i.e., industrial hygienists and health physicists).
Date: January 18, 2000
Creator: Trinoskey, P.A.; Fry, L. & Egbert, W.F.
Partner: UNT Libraries Government Documents Department

Imaging biological molecules with single molecule sensitivity using near-field scanning optical microscopy

Description: We have developed a near-field scanning optical microscope with the sensitivity to detect single fluorescent molecules. Our microscope is based on scanning a sample under a tapered and metal coated fiber optic probe and has an illumination-aperture diameter as small as 100 nm. The microscope simultaneously acquires a shear force image with a height noise of {approximately} 1 nm. We have used this system to demonstrate the detection of single molecules of Rhodamine-6G on silica. In this paper, we explore the use of NSOM for investigations of biological molecules. We have prepared and imaged double-stranded DNA intercalated with thiazole orange homodimer (TOTO); single chromosomes stained with propidium iodide; and {beta}-phycoerythrin proteins on dry, borosilicate-glass surfaces. At very dilute coverages, isolated fluorescent spots are observed for the un-intercalated TOTO dye and for {beta}-phycoerythrin. These fluorescent spots exhibit-emission intensity fluctuations and abrupt bleaching transitions, similar to the intensity behavior observed previously for single Rhodamine 6G molecules on silica.
Date: December 1995
Creator: Ambrose, W. P.; Affleck, R. L.; Goodwin, P.M.; Keller, R. A.; Martin, J.C.; Petty, J. T. et al.
Partner: UNT Libraries Government Documents Department

Optical properties of fluids in microfabricated channels

Description: Microfabricated channels are widely thought to be the key to realizing chemical analysis on a microscopic scale. Chemical and biological information in the microchannels is often probed with optical techniques such as fluorescence, Raman and absorption spectroscopy. However, the optical effects of a microchannel are not well characterized. For example, it is important to understand the optics of the channel in order to optimize optical coupling efficiency. The authors consider various designs for enhancing the sensitivity of fluorescence detection in a microchannel.
Date: March 1, 1997
Creator: French, T.; Gourley, P.L. & McDonald, A.E.
Partner: UNT Libraries Government Documents Department

Detection of Biological Materials Using Ion Mobility Spectroscopy

Description: Traditionally, Ion Mobility Spectroscopy has been used to examine ions of relatively low molecular weight and high ion mobility. In recent years, however, biomolecules such as bradykinin, cytochrome c, bovine pancreatic trypsin inhibitor (BPTI), apomyoglobin, and lysozyme, have been successfully analyzed, but studies of whole bio-organisms have not been performed. In this study an attempt was made to detect and measure the mobility of two bacteriophages, {lambda}-phage and MS2 using electrospray methods to inject the viruses into the ion mobility spectrometer. Using data from Yeh, et al., which makes a comparison between the diameter of non-biologic particles and the specific particle mobility, the particle mobility for the MS2 virus was estimated to be 10{sup {minus}2} cm{sup 2}/volt-sec. From this mobility the drift time of these particles in our spectrometer was calculated to be approximately 65 msec. The particle mobility for the {lambda}-phage virus was estimated to be 10{sup {minus}3} cm{sup 2}/volt-sec. which would result in a drift time of 0.7 sec. Spectra showing the presence of a viral peak at the expected drift time were not observed. However, changes in the reactant ion peak that could be directly attributed to the presence of the viruses were observed. Virus clustering, excessive collisions, and the electrospray injection method limited the performance of this IMS. However, we believe that an instrument specifically designed to analyze such bioagents and utilizing other injection and ionization methods will succeed in directly detecting viruses and bacteria.
Date: March 1, 1999
Creator: Rodacy, P.J.; Sterling, J.P. & Butler, M.A.
Partner: UNT Libraries Government Documents Department

Radiocarbon dating organic residues at the microgram level

Description: Relation between submilligram sample size and {sup 14}C activity for sample blanks (wood from Pliocene sediments) and a contemporary standard (oxalic acid) for catalytically reduced graphitic carbon was examined down to 20 micrograms. Mean age of the 1 mg wood sample blanks is now about 51.3 ka (0.168 pMC) while the mean for 20 microgram sample blanks is about 42.9 ka. So far, the lowest value for a 1-mg wood sample blank is about 60.5 ka (0.056 pMC). We have determined a mean {sup 14}C age of about 9.4 ka from a suite of 7 organic extracts from hair, bone, and matting from a mummified human skeleton from Spirit Cave, Nevada. These data indicate that the Spirit Cave human is the third, oldest directly-dated, human skeleton currently known from North America.
Date: January 1, 1997
Creator: Kirner, D. L.; Burky, R.; Taylor, R. E. & Southon, J. R.
Partner: UNT Libraries Government Documents Department

Extended Rayleigh model of bubble evolution with material strength compared to detailed dynamic simulations

Description: The validity of an extended Rayleigh model for laser generated bubbles in soft tissue is examined. This model includes surface tension, viscosity, a realistic water equation of state, material strength and failure, stress wave emission, and linear growth of interface instabilities. It is compared to dynamic simulations using LATIS, which include stress wave propagation, water equation of state, material strength and failure, and viscosity. The model and the simulations are compared using 1-D spherical geometry with bubble in center and a 2-D cylindrical geometry of a laser fiber in water with a bubble formed at the end of the fiber. The model executes over 300x faster on computer than the dynamic simulations.
Date: March 4, 1997
Creator: Glinsky, M.E.; Amendt, P.A.; Bailey, D.S.; London, R.A.; Rubenchik, A.M. & Strauss, M.
Partner: UNT Libraries Government Documents Department

Physical mechanisms of importance to laser thrombolysis

Description: Bubble dynamics plays a key role in many medical procedures including Laser Thrombolysis (L-T), acoustic and laser lithotripsy, interocular laser surgery, photoacoustic drug delivery, and perhaps ultrasonic imaging. The authors are investigating the effect that interfaces of different materials, especially biological and biomedical materials, have on the dynamics of nearby bubbles. Collapsing bubbles often become nonspherical, resulting in spectacular directed motion with potentially both beneficial and undesirable consequences. This directed motion may explain L-T mass removal and some types of laser-induced tissue damage.
Date: December 31, 1998
Creator: Chapyak, E. J. & Godwin, R. P.
Partner: UNT Libraries Government Documents Department

Analysis of hazardous biological material by MALDI mass spectrometry

Description: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS) has become a valuable tool for analyzing microorganisms. The speed with which data can be obtained from MALDI-MS makes this a potentially important tool for biological health hazard monitoring and forensic applications. The excitement in the mass spectrometry community in this potential field of application is evident by the expanding list of research laboratories pursuing development of MALDI-MS for bacterial identification. Numerous research groups have demonstrated the ability to obtain unique MALDI-MS spectra from intact bacterial cells and bacterial cell extracts. The ability to differentiate strains of the same species has been investigated. Reproducibility of MALDI-MS spectra from bacterial species under carefully controlled experimental conditions has also been demonstrated. Wang et al. have reported on interlaboratory reproducibility of the MALDI-MS analysis of several bacterial species. However, there are still issues that need to be addressed, including the careful control of experimental parameters for reproducible spectra and selection of optimal experimental parameters such as solvent and matrix.
Date: March 21, 2000
Creator: Wahl, KL; Jarman, KH; Valentine, NB; Kingsley, MT; Petersen, CE; Cebula, ST et al.
Partner: UNT Libraries Government Documents Department