Science.gov

Sample records for radiation chemistry applications

  1. Radiation applications of physical chemistry

    NASA Astrophysics Data System (ADS)

    Talrose, V. L.

    1991-05-01

    Many chemical energy problems have a physical chemistry nature connected with chemical kinetics and thermodynamics. In the USSR, the development in this field is associated with the name of N. N. Semenov, who was involved in a large number of fundamental and applied physical chemistry problems. The new Institute of Energy Problems of Chemical Physics of the USSR Academy of Sciences is dealing with some of them. An overview of the Institute's work on radiation applications is presented. Examples of the use of radiation in the power industry (e.g., in coal gasification), tire production, mechanical joints, metal powder production, and sterilization of pharmaceutical products are given. Methods and problems involved in these applications are discussed and the great potential for extensive utilization is demonstrated.

  2. Survey of application of radiation to preparative chemistry

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.

    1973-01-01

    The use of radiation for preparative chemistry in liquid solutions is investigated. General principles are presented and preparations involving reduction, oxidation, polymerization, and decomposition are given. The use of various solvents, water, other inorganic liquids and organic liquids for this purpose is discussed. Finally, a commentary is made on some specific applications where radiation chemistry as a preparative technique may be useful.

  3. Chitosan and radiation chemistry

    NASA Astrophysics Data System (ADS)

    Chmielewski, Andrzej G.

    2010-03-01

    Chitosan as a raw material with special properties has drawn attention of scientists working in the field of radiation processing and natural polymer products development, and also of specialists working in the field of radiation protection and oncologists. Especially the applications concern reduced molecular weight chitosan which still retain its chemical structure; such form of the compound is fostering biological, physical and chemical reactivity of the product. Chitosan degrades into fragments under γ-ray or electron beam irradiation. Antibacterial properties of the product are applied in manufacturing hydrogel for wound dressing and additional healing properties can be achieved by incorporating in the hydrogel matrix chitosan bonded silver clusters. Another possible application of chitosan is in reducing radiation damage to the radiation workers or radiation cured patients. In the case of radioisotopes oral or respiratory chitosan-based materials can be applied as chelators. Applications of chitosan in oncology are also reported.

  4. Application of Radiation Chemistry to Some Selected Technological Issues Related to the Development of Nuclear Energy.

    PubMed

    Bobrowski, Krzysztof; Skotnicki, Konrad; Szreder, Tomasz

    2016-10-01

    The most important contributions of radiation chemistry to some selected technological issues related to water-cooled reactors, reprocessing of spent nuclear fuel and high-level radioactive wastes, and fuel evolution during final radioactive waste disposal are highlighted. Chemical reactions occurring at the operating temperatures and pressures of reactors and involving primary transients and stable products from water radiolysis are presented and discussed in terms of the kinetic parameters and radiation chemical yields. The knowledge of these parameters is essential since they serve as input data to the models of water radiolysis in the primary loop of light water reactors and super critical water reactors. Selected features of water radiolysis in heterogeneous systems, such as aqueous nanoparticle suspensions and slurries, ceramic oxides surfaces, nanoporous, and cement-based materials, are discussed. They are of particular concern in the primary cooling loops in nuclear reactors and long-term storage of nuclear waste in geological repositories. This also includes radiation-induced processes related to corrosion of cladding materials and copper-coated iron canisters, dissolution of spent nuclear fuel, and changes of bentonite clays properties. Radiation-induced processes affecting stability of solvents and solvent extraction ligands as well oxidation states of actinide metal ions during recycling of the spent nuclear fuel are also briefly summarized.

  5. Radiation Chemistry in Organized Assemblies.

    ERIC Educational Resources Information Center

    Thomas, J. K.; Chen, T. S.

    1981-01-01

    Expands the basic concepts regarding the radiation chemistry of simple aqueous systems to more complex, but well defined, organized assemblies. Discusses the differences in behavior in comparison to simple systems. Reviews these techniques: pulse radiolysis, laser flash, photolysis, and steady state irradiation by gamma rays or light. (CS)

  6. The Microwave Applications Theory Program at NRL and Some Chemistry Code Applications to Ionospheric Heating by Microwave Radiation.

    DTIC Science & Technology

    1980-08-26

    RADIATION 1. INTRODUCTION The advent of high power pulsed microwave devices, the magnetrons, at NRL,I which currently generate ’U 1 G Watt at X 1 0 cm and a...separation needed to sustain such a plasma. ( g ) relaxation of the disturbed air and the impact of the late time air chemistry on multi pulse breakdown...and the first negative bands of N 2+ . These two band systems correspond2 7 to N2 +(B2E - X2 E) and N2 (C 3Tu - B 3 g ) transitions, respectively. The

  7. Research needs and opportunities in radiation chemistry workshop

    SciTech Connect

    Barbara, Paul F

    1998-04-19

    heterogeneous systems. These various goals necessitate the development and application of complementary programs of experiment and theory, and will involve the use of nonconventional radiation sources and the study of novel homogeneous and heterogeneous chemical systems. There is also a need to upgrade other types of instrumentation used in radiation chemistry in the national laboratories, including high field electron paramagnetic resonance, and modern analytical tools. The development and enhancement of these various tools will allow for a much wider use of the national radiation chemistry facilities.

  8. Radiation Chemistry and the Radiation Preservation of Food.

    ERIC Educational Resources Information Center

    Taub, Irwin A.

    1981-01-01

    Describes common features in the radiation chemistry of food components, and illustrates how product yields are predicted. Presents data that pertain to the radiolysis of the nitrate ion, metmyoglobin, myosin, and tripalmitin. (CS)

  9. Radiation Chemistry of Potential Europa Plumes

    NASA Astrophysics Data System (ADS)

    Gudipati, M. S.; Henderson, B. L.

    2014-12-01

    Recent detection of atomic hydrogen and atomic oxygen and their correlation to potential water plumes on Europa [Roth, Saur et al. 2014] invoked significant interest in further understanding of these potential/putative plumes on Europa. Unlike on Enceladus, Europa receives significant amount of electron and particle radiation. If the plumes come from trailing hemisphere and in the high radiation flux regions, then it is expected that the plume molecules be subjected to radiation processing. Our interest is to understand to what extent such radiation alterations occur and how they can be correlated to the plume original composition, whether organic or inorganic in nature. We will present laboratory studies [Henderson and Gudipati 2014] involving pulsed infrared laser ablation of ice that generates plumes similar to those observed on Enceladus [Hansen, Esposito et al. 2006; Hansen, Shemansky et al. 2011] and expected to be similar on Europa as a starting point; demonstrating the applicability of laser ablation to simulate plumes of Europa and Enceladus. We will present results from electron irradiation of these plumes to determine how organic and inorganic composition is altered due to radiation. Acknowledgments:This research was enabled through partial funding from NASA funding through Planetary Atmospheres, and the Europa Clipper Pre-Project. B.L.H. acknowledges funding from the NASA Postdoctoral Program for an NPP fellowship. Hansen, C. J., L. Esposito, et al. (2006). "Enceladus' water vapor plume." Science 311(5766): 1422-1425. Hansen, C. J., D. E. Shemansky, et al. (2011). "The composition and structure of the Enceladus plume." Geophysical Research Letters 38. Henderson, B. L. and M. S. Gudipati (2014). "Plume Composition and Evolution in Multicomponent Ices Using Resonant Two-Step Laser Ablation and Ionization Mass Spectrometry." The Journal of Physical Chemistry A 118(29): 5454-5463. Roth, L., J. Saur, et al. (2014). "Transient Water Vapor at Europa's South

  10. Extraterrestrial Radiation Chemistry and Molecular Astronomy

    NASA Technical Reports Server (NTRS)

    Hudson, Reggie L.; Moore, Marla H.

    2009-01-01

    Astronomical observations of both solar system and interstellar regions have revealed a rich chemical inventory that includes most classes of organic molecules and selected inorganics. For example, gas-phase ethylene glycol and SOz have been observed by astronomers, while solidphase detections include OCS, H2O2 , and the cyanate anion.' All of these are found in environments that are, by earthly standards, exceedingly hostile: temperatures of 10 - 100 K, miniscule densities, and near-ubiquitous ionizing-radiation fields. Beyond the simplest chemical species, these conditions have made it difficult-to-impassible to account for the observed molecular abundances using gas-phase chemistry, suggesting solid-phase reactions play an important role. In extraterrestrial environments, cosmic rays, UV photons, and magnetospheric radiation all drive chemical reactions, even at cryogenic temperatures. To study this chemistry, radiation astrochemists conduct experiments on icy materials, frozen under vacuum and exposed to sources such as keV electrons and MeV protons. Compositional changes usually are followed with IR spectroscopy and, in selected cases, more-sensitive mass-spectral techniques. This talk will review some recent results on known and suspected extraterrestrial molecules and ions. Spectra and reaction pathways will be presented, and predictions made for interstellar chemistry and the chemistry of selected solar system objects. Some past radiation-chemical contributions, and future needs, will be explored.

  11. Radiation chemistry of synthetic waste

    SciTech Connect

    Meisel, D.; Diamond, H.; Horwitz, E.P.; Jonah, C.D.; Matheson, M.S.; Sauer, M.C. Jr.; Sullivan, J.C.

    1991-11-01

    The yield of H{sub 2} from radiolysis of aqueous solutions is substantially reduced by the presence of nitrate and nitrite in the waste solutions. Nitrate is more efficient in scavenging the precursors to H{sub 2} than is nitrite, therefore, the latter should be maintained at higher levels if minimization of radiolytic gas production is required. Nitrate is the major scavenger for e{sub aq}{sup {minus}} and nitrite is the major scavenger for H atoms. At the concentration levels of the waste solutions some fraction of the radiation energy will be absorbed directly by the solutes, primarily the nitrate/nitrite components. Organic additive will increase the generation of H{sub 2} and mechanistic information is available to allow predictive modeling of trends in the rate of the generation. Physical parameters such as temperature, viscosity, and pressure will not significantly affect the gas generation relative to its generation under normal conditions. Radiolytic generation of N{sub 2}O is very inefficient in the absence of organic solutes. No mechanistic information is available on its generation in the presence of organic additives. At the concentration levels of the inorganic salts in the waste solutions, it will be very difficult to find a chemical additive that could efficiently reduce the yield of the generated H{sub 2}, except, perhaps, increasing the concentration of the nitrite/nitrate components.

  12. Radiation chemistry for modern nuclear energy development

    NASA Astrophysics Data System (ADS)

    Chmielewski, Andrzej G.; Szołucha, Monika M.

    2016-07-01

    Radiation chemistry plays a significant role in modern nuclear energy development. Pioneering research in nuclear science, for example the development of generation IV nuclear reactors, cannot be pursued without chemical solutions. Present issues related to light water reactors concern radiolysis of water in the primary circuit; long-term storage of spent nuclear fuel; radiation effects on cables and wire insulation, and on ion exchangers used for water purification; as well as the procedures of radioactive waste reprocessing and storage. Radiation effects on materials and enhanced corrosion are crucial in current (II/III/III+) and future (IV) generation reactors, and in waste management, deep geological disposal and spent fuel reprocessing. The new generation of reactors (III+ and IV) impose new challenges for radiation chemists due to their new conditions of operation and the usage of new types of coolant. In the case of the supercritical water-cooled reactor (SCWR), water chemistry control may be the key factor in preventing corrosion of reactor structural materials. This paper mainly focuses on radiation effects on long-term performance and safety in the development of nuclear power plants.

  13. Radiation Chemistry and Photochemistry of Ionic Liquids

    SciTech Connect

    Wishart, J.F.; Takahaski, K.

    2010-12-01

    As our understanding of ionic liquids and their tunable properties has grown, it is possible to see many opportunities for ionic liquids to contribute to the sustainable use of energy. The potential safety and environmental benefits of ionic liquids, as compared to conventional solvents, have attracted interest in their use as processing media for the nuclear fuel cycle. Therefore, an understanding of the interactions of ionizing radiation and photons with ionic liquids is strongly needed. However, the radiation chemistry of ionic liquids is still a relatively unexplored topic although there has been a significant increase in the number of researchers in the field recently. This article provides a brief introduction to ionic liquids and their interesting properties, and recent advances in the radiation chemistry and photochemistry of ionic liquids. In this article, we will mainly focus on excess electron dynamics and radical reaction dynamics. Because solvation dynamics processes in ionic liquids are much slower than in molecular solvents, one of the distinguishing characteristics is that pre-solvated electrons play an important role in ionic liquid radiolysis. It will be also shown that the reaction dynamics of radical ions is significantly different from that observed in molecular solvents because of the Coulombic screening effects and electrostatic interactions in ionic liquids.

  14. Chemistry of MOS-LSI radiation hardening

    NASA Technical Reports Server (NTRS)

    Grunthaner, P.

    1985-01-01

    The objective of this task was to obtain chemical information on MOS test samples. Toward this end, high resolution X-ray photoemission spectroscopy (XPS) has been the primary techniques used to characterize the chemistry and structure of the SiO2/Si interface for a variety of MOS structures with differing degrees of susceptibility to damage by ionizing radiation. The major accomplishments of this program are: (1) the identification of a structurally distinct region of SiO2 in the near-interfacial region of thermal SiO2 on Si; (2) the identification in the near-interfacial region of SiO2 structural differences between radiation hard and soft gate oxides; (3) the direct observation of radiation-induced damage sites in thermal SiO2 with XPS using in situ electron stress; (4) the correlation of suboxide state distributions at the SiO2/Si interface with processing parameters and radiation susceptibility; (5) the development of a chemical mechanism for radiation-induced interface state generation in SiO2/Si structures; and (6) the development benign chemical profiling techniques which permit the investigation of oxide/semiconductor structures using surface sensitive electron spectroscopic techniques.

  15. Use of radiation in preparative chemistry

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; Marksik, S. J.; May, C. E.; Lad, R. A.

    1971-01-01

    A summary and updating of previous work on the use of radiation chemistry for the preparation of pure materials are presented. Work was chiefly concerned with the reduction of metal salts in solution to the free metal using 2 MeV electrons. Metals deposited from aqueous solution are copper, silver, zinc, cadmium, thallium, tin, lead, antimony, iron, nickel, cobalt, and palladium. Dry organic solvents were evaluated for the deposition of metals based on a study involving deposition of antimony from soltions of antimony (III) chloride. The use of organic liquids for the preparation of anhydrous metal halides is also presented. Reaction mechanisms for both organic liquids and aqueous system are discussed.

  16. Radiation Chemistry of Advanced TALSPEAK Flowsheet

    SciTech Connect

    Mincher, Bruce; Peterman, Dean; Mcdowell, Rocklan; Olson, Lonnie; Lumetta, Gregg J.

    2013-08-28

    This report summarizes the results of initial experiments designed to understand the radiation chemistry of an Advanced TALSPEAK process for separating trivalent lanthanides form the actinides. Biphasic aerated samples were irradiated and then analyzed for post-irradiation constituent concentrations and solvent extraction distribution ratios. The effects of irradiation on the TALSPEAK and Advanced TALSPEAK solvents were similar, with very little degradation of the organic phase extractant. Decomposition products were detected, with a major product in common for both solvents. This product may be responsible for the slight increase in distribution ratios for Eu and Am with absorbed dose, however; separation factors were not greatly affected.

  17. The radiation chemistry of ionic liquids: A review

    SciTech Connect

    Mincher, Bruce J.; Wishart, James F.

    2014-07-03

    Ionic liquids have received increasing attention as media for radiochemical separations. Recent literature includes examinations of the efficiencies and mechanisms of the solvent extraction of lanthanides, actinides and fission products into ionic liquid solutions. For radiochemical applications, including as replacement solvents for nuclear fuel reprocessing, a thorough understanding of the radiation chemistry of ionic liquids will be required. Such an understanding can be achieved based on a combination of steady-state radiolysis experiments coupled with post-irradiation product identification and pulse-radiolysis experiments to acquire kinetic information. These techniques allow for the elucidation of radiolytic mechanisms. This contribution reviews the current ionic liquid radiation chemistry literature as it affects separations, with these considerations in mind.

  18. The radiation chemistry of ionic liquids: A review

    DOE PAGES

    Mincher, Bruce J.; Wishart, James F.

    2014-07-03

    Ionic liquids have received increasing attention as media for radiochemical separations. Recent literature includes examinations of the efficiencies and mechanisms of the solvent extraction of lanthanides, actinides and fission products into ionic liquid solutions. For radiochemical applications, including as replacement solvents for nuclear fuel reprocessing, a thorough understanding of the radiation chemistry of ionic liquids will be required. Such an understanding can be achieved based on a combination of steady-state radiolysis experiments coupled with post-irradiation product identification and pulse-radiolysis experiments to acquire kinetic information. These techniques allow for the elucidation of radiolytic mechanisms. This contribution reviews the current ionic liquidmore » radiation chemistry literature as it affects separations, with these considerations in mind.« less

  19. Microcomputer Applications in Analytical Chemistry.

    ERIC Educational Resources Information Center

    Long, Joseph W.

    The first part of this paper addresses the following topics: (1) the usefulness of microcomputers; (2) applications for microcomputers in analytical chemistry; (3) costs; (4) major microcomputer systems and subsystems; and (5) which microcomputer to buy. Following these brief comments, the major focus of the paper is devoted to a discussion of…

  20. Chemistry of radiation damage to wire chambers

    SciTech Connect

    Wise, J.

    1992-08-01

    Proportional counters are used to study aspects of radiation damage to wire chambers (wire aging). Principles of low-pressure, rf plasma chemistry are used to predict the plasma chemistry in electron avalanches (1 atm, dc). (1) Aging is studied in CF{sub 4}/iC{sub 4}H{sub 10} gas mixtures. Wire deposits are analyzed by Auger electron spectroscopy. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained current is observed in CF{sub 4}-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF{sub 4}, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF{sub 4}/iC{sub 4}H{sub 10} gases. Practical guidelines suggested by the model are discussed. (2) Data are presented to suggest that trace amounts of Freons do not affect aging rates in either dimethyl ether or Ar/C{sub 2}H{sub 6}. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl{sub 3}F) in the counter gas. An increase in the concentration of Freon 11 in dimethyl ether is caused by a distillation process in the gas supply bottle and is a natural consequence of the unequal volatilities of the two compounds.

  1. Grackle: Chemistry and radiative cooling library for astrophysical simulations

    NASA Astrophysics Data System (ADS)

    Smith, Britton D.; Bryan, Greg L.; Glover, Simon C. O.; Goldbaum, Nathan J.; Turk, Matthew J.; Regan, John; Wise, John H.; Schive, Hsi-Yu; Abel, Tom; Emerick, Andrew; O'Shea, Brian W.; Anninos, Peter; Hummels, Cameron B.; Khochfar, Sadegh

    2016-12-01

    The chemistry and radiative cooling library Grackle provides options for primordial chemistry and cooling, photo-heating and photo-ionization from UV backgrounds, and support for user-provided arrays of volumetric and specific heating rates for astrophysical simulations and models. The library provides functions to update chemistry species; solve radiative cooling and update internal energy; and calculate cooling time, temperature, pressure, and ratio of specific heats (gamma), and has interfaces for C, C++, Fortran, and Python codes.

  2. Radiation Chemistry 2008 Gordon Research Conference - July 6-11, 2008

    SciTech Connect

    David M. Bartels

    2009-05-15

    Radiation Chemistry is chemistry initiated by ionizing radiation: i.e. photons or particles with energy sufficient to create charge pairs and/or free radicals in a medium. The important transients include conduction band electrons and 'holes', excitons, ionic and neutral free radicals, highly excited states, and solvated electrons. Effects of radiation span timescales from the energy deposition in femtoseconds, through geminate recombination in picoseconds and nanoseconds, to fast radical chemistry in microseconds and milliseconds, and ultimately to processes like cancer occurring decades later. The radiation sources used to study these processes likewise run from femtosecond lasers to nanosecond accelerators to years of gamma irradiation. As a result the conference has a strong interdisciplinary flavor ranging from fundamental physics to clinical biology. While the conference focuses on fundamental science, application areas highlighted in the present conference will include nuclear power, polymer processing, and extraterrestrial chemistry.

  3. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1990-01-01

    The continued development and improvement of the viscous shock layer (VSL) nonequilibrium chemistry blunt body engineering code, the incorporation in a coupled manner of radiation models into the VSL code, and the initial development of appropriate precursor models are presented.

  4. Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns

    SciTech Connect

    Wishart, J.F.

    2011-06-12

    Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs generally have low volatilities and are combustion-resistant, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of primary radiation chemistry, charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of reactions and product distributions. We study these issues by characterization of primary radiolysis products and measurements of their yields and reactivity, quantification of electron solvation dynamics and scavenging of electrons in different states of solvation. From this knowledge we wish to learn how to predict radiolytic mechanisms and control them or mitigate their effects on the properties of materials used in nuclear fuel processing, for example, and to apply IL radiation chemistry to answer questions about general chemical reactivity in ionic liquids that will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that the slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increase the importance of pre-solvated electron reactivity and consequently alter product distributions and subsequent chemistry. This difference from conventional solvents has profound effects on predicting and controlling radiolytic yields

  5. 2012 RADIATION CHEMISTRY GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR, JULY 28, - AUGUST 3, 2012

    SciTech Connect

    y LaVerne

    2012-08-03

    The overarching objective of this conference is to catalyze the interchange of new ideas and recent discoveries within the basic radiation sciences of physics, chemistry, and biology, and to facilitate translating this knowledge to applications in medicine and industry. The 9 topics for the GRC are: "œFrom Energy Absorption to Disease", "œBiodosimetry after a Radiological Incident," "œTrack Structure and Low Energy Electrons," "Free Radical Processes in DNA and Proteins," "Irradiated Polymers for Industrial/ Medical Applications," "Space Radiation Chemistry/Biology," "Nuclear Power and Waste Management," "Nanoparticles and Surface Interfaces", and the "Young Investigator" session.

  6. RADIATION CHEMISTRY 2010 GORDON RESEARCH CONFERENCE JULY 18-23

    SciTech Connect

    Thomas Orlando

    2010-07-23

    The 2010 Gordon Conference on Radiation Chemistry will present cutting edge research regarding the study of radiation-induced chemical transformations. Radiation Chemistry or 'high energy' chemistry is primarily initiated by ionizing radiation: i.e. photons or particles with energy sufficient to create conduction band electrons and 'holes', excitons, ionic and neutral free radicals, highly excited states, and solvated electrons. These transients often interact or 'react' to form products vastly different than those produced under thermal equilibrium conditions. The non-equilibrium, non-thermal conditions driving radiation chemistry exist in plasmas, star-forming regions, the outer solar system, nuclear reactors, nuclear waste repositories, radiation-based medical/clinical treatment centers and in radiation/materials processing facilities. The 2010 conference has a strong interdisciplinary flavor with focus areas spanning (1) the fundamental physics and chemistry involved in ultrafast (atto/femtosecond) energy deposition events, (2) radiation-induced processes in biology (particularly spatially resolved studies), (3) radiation-induced modification of materials at the nanoscale and cosmic ray/x-ray mediated processes in planetary science/astrochemistry. While the conference concentrates on fundamental science, topical applied areas covered will also include nuclear power, materials/polymer processing, and clinical/radiation treatment in medicine. The Conference will bring together investigators at the forefront of their field, and will provide opportunities for junior scientists and graduate students to present work in poster format or as contributors to the Young Investigator session. The program and format provides excellent avenues to promote cross-disciplinary collaborations.

  7. High fidelity chemistry and radiation modeling for oxy -- combustion scenarios

    NASA Astrophysics Data System (ADS)

    Abdul Sater, Hassan A.

    To account for the thermal and chemical effects associated with the high CO2 concentrations in an oxy-combustion atmosphere, several refined gas-phase chemistry and radiative property models have been formulated for laminar to highly turbulent systems. This thesis examines the accuracies of several chemistry and radiative property models employed in computational fluid dynamic (CFD) simulations of laminar to transitional oxy-methane diffusion flames by comparing their predictions against experimental data. Literature review about chemistry and radiation modeling in oxy-combustion atmospheres considered turbulent systems where the predictions are impacted by the interplay and accuracies of the turbulence, radiation and chemistry models. Thus, by considering a laminar system we minimize the impact of turbulence and the uncertainties associated with turbulence models. In the first section of this thesis, an assessment and validation of gray and non-gray formulations of a recently proposed weighted-sum-of-gray gas model in oxy-combustion scenarios was undertaken. Predictions of gas, wall temperatures and flame lengths were in good agreement with experimental measurements. The temperature and flame length predictions were not sensitive to the radiative property model employed. However, there were significant variations between the gray and non-gray model radiant fraction predictions with the variations in general increasing with decrease in Reynolds numbers possibly attributed to shorter flames and steeper temperature gradients. The results of this section confirm that non-gray model predictions of radiative heat fluxes are more accurate than gray model predictions especially at steeper temperature gradients. In the second section, the accuracies of three gas-phase chemistry models were assessed by comparing their predictions against experimental measurements of temperature, species concentrations and flame lengths. The chemistry was modeled employing the Eddy

  8. Plasma chemistry and its applications

    NASA Technical Reports Server (NTRS)

    Hozumi, K.

    1980-01-01

    The relationship between discharge phenomena and plasma chemistry, as well as the equipment and mechanisms of plasma chemical reactions are described. Various areas in which plasma chemistry is applied are surveyed, such as: manufacturing of semiconductor integrated circuits; synthetic fibers; high polymer materials for medical uses; optical lenses; and membrane filters (reverse penetration films).

  9. Ion-Molecule Reactions in Gas Phase Radiation Chemistry.

    ERIC Educational Resources Information Center

    Willis, Clive

    1981-01-01

    Discusses some aspects of the radiation chemistry of gases, focusing on the ion-molecule and charge neutralization reactions which set study of the gas phase apart. Uses three examples that illustrate radiolysis, describing the radiolysis of (1) oxygen, (2) carbon dioxide, and (3) acetylene. (CS)

  10. Ionic Liquids: Radiation Chemistry, Solvation Dynamics and Reactivity Patterns

    SciTech Connect

    Wishart,J.F.

    2008-09-29

    Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate

  11. Solved? The reductive radiation chemistry of alanine.

    PubMed

    Pauwels, Ewald; De Cooman, Hendrik; Waroquier, Michel; Hole, Eli O; Sagstuen, Einar

    2014-02-14

    The structural changes throughout the entire reductive radiation-induced pathway of l-α-alanine are solved on an atomistic level with the aid of periodic DFT and nudged elastic band (NEB) simulations. This yields unprecedented information on the conformational changes taking place, including the protonation state of the carboxyl group in the "unstable" and "stable" alanine radicals and the internal transformation converting these two radical variants at temperatures above 220 K. The structures of all stable radicals were verified by calculating EPR properties and comparing those with experimental data. The variation of the energy throughout the full radiochemical process provides crucial insight into the reason why these structural changes and rearrangements occur. Starting from electron capture, the excess electron quickly localizes on the carbon of a carboxyl group, which pyramidalizes and receives a proton from the amino group of a neighboring alanine molecule, forming a first stable radical species (up to 150 K). In the temperature interval 150-220 K, this radical deaminates and deprotonates at the carboxyl group, the detached amino group undergoes inversion and its methyl group sustains an internal rotation. This yields the so-called "unstable alanine radical". Above 220 K, triggered by the attachment of an additional proton on the detached amino group, the radical then undergoes an internal rotation in the reverse direction, giving rise to the "stable alanine radical", which is the final stage in the reductive radiation-induced decay of alanine.

  12. Radiation chemistry in the Jovian stratosphere - Laboratory simulations

    NASA Technical Reports Server (NTRS)

    Mcdonald, Gene D.; Thompson, W. R.; Sagan, Carl

    1992-01-01

    The results of the present low-pressure/continuous-flow laboratory simulations of H2/He/CH4/NH3 atmospheres' plasma-induced chemistry indicate radiation yields of both hydrocarbon and N2-containing organic compounds which increase with decreasing pressure. On the basis of these findings, upper limits of 1 million-1 billion molecules/sq cm/sec are established for production rates of major auroral-chemistry species in the Jovian stratosphere. It is noted that auroral processes may account for 10-100 percent of the total abundances of most of the observed polar-region organic species.

  13. Radiation physics and chemistry of biomolecules. Recent developments

    NASA Astrophysics Data System (ADS)

    Spotheim-Maurizot, Melanie

    2016-11-01

    A chapter of the book ;Radiation chemistry. From basics to application in materials and life sciences (EDP Science, Paris, France, 2008); was devoted to the state-of-the-art in the research on ionizing radiation (IR) effects on biomolecules. An update, eight years later, seemed pertinent enough to the editors of this journal who accepted to dedicate a Special Issue to the latest developments in this area of high interest for cancer radiotherapy, nuclear workers' radioprotection and food radiosterilisation. We sincerely thank them and the authors who accepted to present reviews of their most recent work. Obviously, only a small part of the research in the fascinating domain of molecular radiobiology can be covered here. Some articles are presenting the contribution of biophysical models and computational techniques to the understanding of IR effects on molecules such as DNA and proteins, or on larger systems such as chromatin, chromosomes and even cells (Nikjoo et al., Štěpán & Davídková, Ballarini & Carante, and Nikitaki et al.). In these papers, as well as in many others, several qualities of IR are compared in order to explain the observed differences of effects. The damages induced by the low energy electrons and new techniques involved in their study are discussed in great detail (Sanche and Fromm & Boulanouar). The chemistry behind the IR induced damages (single or clustered), studied in many laboratories around the world is presented in several papers (Cadet & Wagner, Sevilla et al., Chatgilialoglu et al., and Greenberg). One of them addresses a very useful comparison between the effects of IR and UV exposure on DNA (Ravanat & Douki). The majority of the papers in this Special Issue is dealing with DNA and this reflects the real situation: damages of DNA are more studied than those of other biomolecules. This is due to the role of DNA as main support of hereditary information. Nevertheless, more and more studies are outlining the influence of epigenetic

  14. Radiation Chemistry of Simulated (99)Mo Product

    SciTech Connect

    Carson, S.D.; Garcia, M.J.; McDonald, M.J.; Simpson, R.L.; Tallant, D.R.

    1998-11-06

    PharrnaceuticaI houses that produce {sup 99}Tc/{sup 99}Tc generators have on occasion received {sup 99}Mo that contained a black precipitate. Addition of sodium hypochlorite to product bottles prior to shipment prevents precipitate formation, indicating the precipitate is a reduced form of Mo. The radiation effects of the dose from {sup 99}Mo on the product and product bottle have been determined by irradiating simulated {sup 99}Mo product solutions with the {sup 60}Co source at Sandia National Laboratories' Gamma Irradiation Facility (GE). The GIF experiment successfully generated a black precipitate in amounts sufficient for isolation and analysis by infrared and Rrunan spectroscopy. Changes in the pH of the basic {sup 99}Mo product solution during irradiation were monitored by titration. ResuIts of these analyses and the nature of the process that generates the precipitate, a mixture of molybdenum oxides that forms in plastic bottles, but not in glass containers, are discussed.

  15. IONIC LIQUIDS: RADIATION CHEMISTRY, SOLVATION DYNAMICS AND REACTIVITY PATTERNS.

    SciTech Connect

    WISHART,J.F.

    2007-10-01

    energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, which will aid in the development of applications listed above. Very early in our radiolysis studies it became evident that slow solvation dynamics of the excess electron in ILs (which vary over a wide viscosity range) increases the importance of pre-solvated electron reactivity and consequently alters product distributions. Parallel studies of IL solvation phenomena using coumarin-153 dynamic Stokes shifts and polarization anisotropy decay rates are done to compare with electron solvation studies and to evaluate the influence of ILs on charge transport processes. Methods. Picosecond pulse radiolysis studies at BNL

  16. Chemistry Teachers' Knowledge and Application of Models

    ERIC Educational Resources Information Center

    Wang, Zuhao; Chi, Shaohui; Hu, Kaiyan; Chen, Wenting

    2014-01-01

    Teachers' knowledge and application of model play an important role in students' development of modeling ability and scientific literacy. In this study, we investigated Chinese chemistry teachers' knowledge and application of models. Data were collected through test questionnaire and analyzed quantitatively and qualitatively. The result indicated…

  17. Chemical applications of synchrotron radiation: Workshop report

    SciTech Connect

    Not Available

    1989-04-01

    The most recent in a series of topical meetings for Advanced Photon Source user subgroups, the Workshop on Chemical Applications of Synchrotron Radiation (held at Argonne National Laboratory, October 3-4, 1988) dealt with surfaces and kinetics, spectroscopy, small-angle scattering, diffraction, and topography and imaging. The primary objectives were to provide an educational resource for the chemistry community on the scientific research being conducted at existing synchrotron sources and to indicate some of the unique opportunities that will be made available with the Advanced Photon Source. The workshop organizers were also interested in gauging the interest of chemists in the field of synchrotron radiation. Interest expressed at the meeting has led to initial steps toward formation of a Chemistry Users Group at the APS. Individual projects are processed separately for the data bases.

  18. H atom probes of radiation chemistry: Solids and liquids

    SciTech Connect

    Trifunac, A.D.; Shkrob, I.A.

    1998-12-31

    H atoms are ubiquitous in radiation chemistry. Radiolysis of most substances yield H atoms and studies of the mechanisms of their production are as old as the field of radiation chemistry. The problem is that study or products does not easily reveal the chemical mechanisms involved even with the clever use of isotopes. Time-resolved pulsed electron paramagnetic resonance (EPR) was used to study formation and decay kinetics of spin-polarized mobile H atoms in radiolysis of wet fused silica containing {approximately} 1,200 ppm of SiOH groups. Two reactions of H atoms can be distinguished: a slow component corresponding to scavenging of H atoms by metastable paramagnetic centers and a fast component which is ascribed to a reaction of a short-lived small polaron (intrinsic hole) with H atoms.

  19. Halogen chemistry reduces tropospheric O3 radiative forcing

    NASA Astrophysics Data System (ADS)

    Sherwen, Tomás; Evans, Mat J.; Carpenter, Lucy J.; Schmidt, Johan A.; Mickley, Loretta J.

    2017-01-01

    Tropospheric ozone (O3) is a global warming gas, but the lack of a firm observational record since the preindustrial period means that estimates of its radiative forcing (RFTO3) rely on model calculations. Recent observational evidence shows that halogens are pervasive in the troposphere and need to be represented in chemistry-transport models for an accurate simulation of present-day O3. Using the GEOS-Chem model we show that tropospheric halogen chemistry is likely more active in the present day than in the preindustrial. This is due to increased oceanic iodine emissions driven by increased surface O3, higher anthropogenic emissions of bromo-carbons, and an increased flux of bromine from the stratosphere. We calculate preindustrial to present-day increases in the tropospheric O3 burden of 113 Tg without halogens but only 90 Tg with, leading to a reduction in RFTO3 from 0.43 to 0.35 Wm-2. We attribute ˜ 50 % of this reduction to increased bromine flux from the stratosphere, ˜ 35 % to the ocean-atmosphere iodine feedback, and ˜ 15 % to increased tropospheric sources of anthropogenic halogens. This reduction of tropospheric O3 radiative forcing due to halogens (0.087 Wm-2) is greater than that from the radiative forcing of stratospheric O3 (˜ 0.05 Wm-2). Estimates of RFTO3 that fail to consider halogen chemistry are likely overestimates (˜ 25 %).

  20. Radiation chemistry in solvent etxraction: FY2011 research

    SciTech Connect

    Bruce J. Mincher; Stephen P. Mezyk; Leigh R. Martin

    2011-09-01

    This report summarizes work accomplished under the Fuel Cycle Research and Development (FCR&D) program in the area of radiation chemistry during FY 2011. The tasks assigned during FY 2011 included: (1) Continue measurements free radical reaction kinetics in the organic phase; (2) Continue development of an alpha-radiolysis program and compare alpha and gamma radiolysis for CMPO; (3) Initiate an effort to understand dose rate effects in radiation chemistry; and (4) Continued work to characterize TALSPEAK radiation chemistry, including the examination of metal complexed ligand kinetics. Progress made on each of these tasks is reported here. Briefly, the method developed to measure the kinetics of the reactions of the NO3 radical with solvent extraction ligands in organic solution during FY10 was extended here to a number of compounds to better understand the differences between radical reactions in the organic versus aqueous phases. The alpha-radiolysis program in FY11 included irradiations of CMPO solutions with 244Cm, 211At and the He ion beam, for comparison to gamma irradiations, and a comparison of the gamma irradiation results for CMPO at three different gamma dose rates. Finally, recent results for TALSPEAK radiolysis are reported, summarizing the latest in an effort to understand how metal complexation to ligands affects their reaction kinetics with free radicals.

  1. Radiation chemistry in solvent extraction: FY2010 Research

    SciTech Connect

    Bruce J. Mincher; Leigh R. Martin; Stephen P. Mezyk

    2010-09-01

    This report summarizes work accomplished under the Fuel Cycle Research and Development (FCR&D) program in the area of radiation chemistry during FY 2010. The tasks assigned during FY 2010 included: • Development of techniques to measure free radical reaction kinetics in the organic phase. • Initiation of an alpha-radiolysis program • Initiation of an effort to understand dose rate effects in radiation chemistry • Continued work to characterize TALSPEAK radiation chemistry Progress made on each of these tasks is reported here. Briefly, a method was developed and used to measure the kinetics of the reactions of the •NO3 radical with solvent extraction ligands in organic solution, and the method to measure •OH radical reactions under the same conditions has been designed. Rate constants for the CMPO and DMDOHEMA reaction with •NO3 radical in organic solution are reported. Alpha-radiolysis was initiated on samples of DMDOHEMA in alkane solution using He ion beam irradiation and 211At isotope irradiation. The samples are currently being analyzed for comparison to DMDOHEMA ?-irradiations using a custom-developed mass spectrometric method. Results are also reported for the radiolytic generation of nitrous acid, in ?-irradiated nitric acid. It is shown that the yield of nitrous acid is unaffected by an order-of-magnitude change in dose rate. Finally, recent results for TALSPEAK radiolysis are reported, summarizing the effects on solvent extraction efficiency due to HDEHP irradiation, and the stable products of lactic acid and DTPA irradiation. In addition, results representing increased scope are presented for the radiation chemistry program. These include an investigation of the effect of metal complexation on radical reaction kinetics using DTPA as an example, and the production of a manuscript reporting the mechanism of Cs-7SB radiolysis. The Cs-7SB work takes advantage of recent results from a current LDRD program to understand the fundamental chemistry

  2. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1990-01-01

    The primary tasks during January 1990 to June 1990 have been the development and evaluation of various electron and electron-electronic energy equation models, the continued development of improved nonequilibrium radiation models for molecules and atoms, and the continued development and investigation of precursor models and their effects. In addition, work was initiated to develop a vibrational model for the viscous shock layer (VSL) nonequilibrium chemistry blunt body engineering code. Also, an effort was started associated with the effects of including carbon species, say from an ablator, in the flowfield.

  3. Radiation and Turbulence-Chemistry-Soot-Radiation Interactions in a High-Pressure Turbulent Spray Flame

    NASA Astrophysics Data System (ADS)

    Ferreyro, S.; Paul, C.; Sircar, A.; Imren, A.; Haworth, D. C.; Roy, S.; Modest, M. F.

    2016-11-01

    Simulations are performed of a transient high-pressure turbulent n-dodecane spray flame under engine-relevant conditions. An unsteady RANS formulation is used, with detailed chemistry, a two-equation soot model, various radiation heat transfer models, and a particle-based transported composition probability density function (PDF) method to account for composition and temperature. The PDF model results are compared with those from a locally well-stirred reactor (WSR) model to quantify the effects of turbulence-chemistry-soot-radiation interactions. Computed liquid and vapor penetration versus time, ignition delay, and flame lift-off are in good agreement with experiment, and relatively small differences are seen between the WSR and PDF models for these global quantities. Computed soot levels and spatial distributions from the WSR and PDF models show large differences, with PDF results being in better agreement with experimental measurements. A photon Monte Carlo method with line-by-line spectral resolution is used to compute the spectral intensity distribution of the radiation reachingthe wall. This provides new insight into the relative importance of molecular gas radiation versus soot radiation, and the importance of unresolved turbulent fluctuations on radiative heat transfer.

  4. Applications of physical chemistry to glass technology

    NASA Astrophysics Data System (ADS)

    Stewart, Ogie Gregory

    2001-07-01

    Industrial manufacturing of glass, called float glass, involves a process in which flat pieces of glass are produced by pouring molten glass on a bath of molten tin metal. The glass is then coated with thin film coatings for such applications as solar radiation control and "privacy" glass. In this thesis, principles of physical chemistry are applied to selected aspects of glass production and thin film coatings in an effort to better understand these processes with the hope of improving film and glass quality. The research described here consists of three major studies. Part 1 describes the production of thin films by Atmospheric Pressure Chemical Vapor Deposition (APCVD) and characterization of the films by various analytical techniques. Vanadium oxide films were produced from vanadium (IV) chloride and each of several alcohols to determine the feasibility of this method of deposition and to investigate its use in an electrochromic device. The focus here was to investigate the levels of carbon contamination in the films. It was found that the level of carbon present in the films depend on the type of amine used. Part 2 is an investigation of the flow dynamics that occur during the two thin film deposition processes. APCVD and Powder Spray Pyrolysis (PSP). Information regarding flow dynamics and particle distribution in the region above the films' substrates were obtained and related to film formation and quality. Part 3 is a kinetic study of the gas phase reactions that occur in the vapor region above the glass during float glass production. A kinetic model of the possible reactions was devised and integrated to predict the formation of these impurities with time. An experimental setup to test the model's predictions is also discussed. The research described in this thesis lays the groundwork for several possibilities for future work. Electrochromic films can be produced by APCVD to construct an all-solid-state device. Two dimensional imaging coupled with Laser

  5. The effects of atmospheric chemistry on radiation budget in the Community Earth Systems Model

    NASA Astrophysics Data System (ADS)

    Choi, Y.; Czader, B.; Diao, L.; Rodriguez, J.; Jeong, G.

    2013-12-01

    The Community Earth Systems Model (CESM)-Whole Atmosphere Community Climate Model (WACCM) simulations were performed to study the impact of atmospheric chemistry on the radiation budget over the surface within a weather prediction time scale. The secondary goal is to get a simplified and optimized chemistry module for the short time period. Three different chemistry modules were utilized to represent tropospheric and stratospheric chemistry, which differ in how their reactions and species are represented: (1) simplified tropospheric and stratospheric chemistry (approximately 30 species), (2) simplified tropospheric chemistry and comprehensive stratospheric chemistry from the Model of Ozone and Related Chemical Tracers, version 3 (MOZART-3, approximately 60 species), and (3) comprehensive tropospheric and stratospheric chemistry (MOZART-4, approximately 120 species). Our results indicate the different details in chemistry treatment from these model components affect the surface temperature and impact the radiation budget.

  6. Medical Applications of Synchrotron Radiation

    DOE R&D Accomplishments Database

    Thomlinson, W.

    1991-10-01

    Ever since the first diagnostic x-ray was done in the United States on February 3, 1896, the application of ionizing radiation to the field of medicine has become increasingly important. Both in clinical medicine and basic research the use of x-rays for diagnostic imaging and radiotherapy is now widespread. Radiography, angiography, CAT and PETT scanning, mammography, and nuclear medicine are all examples of technologies developed to image the human anatomy. In therapeutic applications, both external and internal sources of radiation are applied to the battle against cancer. The development of dedicated synchrotron radiation sources has allowed exciting advances to take place in many of these applications. The new sources provide tunable, high-intensity monochromatic beams over a wide range of energies which can be tailored to specific programmatic needs. This paper surveys those areas of medical research in which synchrotron radiation facilities are actively involved.

  7. Medical applications of synchrotron radiation

    SciTech Connect

    Thomlinson, W.

    1991-10-01

    Ever since the first diagnostic x-ray was done in the United States on February 3, 1896, the application of ionizing radiation to the field of medicine has become increasingly important. Both in clinical medicine and basic research the use of x-rays for diagnostic imaging and radiotherapy is now widespread. Radiography, angiography, CAT and PETT scanning, mammography, and nuclear medicine are all examples of technologies developed to image the human anatomy. In therapeutic applications, both external and internal sources of radiation are applied to the battle against cancer. The development of dedicated synchrotron radiation sources has allowed exciting advances to take place in many of these applications. The new sources provide tunable, high-intensity monochromatic beams over a wide range of energies which can be tailored to specific programmatic needs. This paper surveys those areas of medical research in which synchrotron radiation facilities are actively involved.

  8. Radiation chemistry of salicylic and methyl substituted salicylic acids: Models for the radiation chemistry of pharmaceutical compounds

    NASA Astrophysics Data System (ADS)

    Ayatollahi, Shakiba; Kalnina, Daina; Song, Weihua; Turks, Maris; Cooper, William J.

    2013-11-01

    Salicylic acid and its derivatives are components of many medications and moieties found in numerous pharmaceutical compounds. They have been used as models for various pharmaceutical compounds in pharmacological studies, for the treatment of pharmaceuticals and personal care products (PPCPs), and, reactions with natural organic matter (NOM). In this study, the radiation chemistry of benzoic acid, salicylic acid and four methyl substituted salicylic acids (MSA) is reported. The absolute bimolecular reaction rate constants for hydroxyl radical reaction with benzoic and salicylic acids as well as 3-methyl-, 4-methyl-, 5-methyl-, and 6-methyl-salicylic acid were determined (5.86±0.54)×109, (1.07±0.07)×1010, (7.48±0.17)×109, (7.31±0.29)×109, (5.47±0.25)×109, (6.94±0.10)×109 (M-1 s-1), respectively. The hydrated electron reaction rate constants were measured (3.02±0.10)×109, (8.98±0.27)×109, (5.39±0.21)×109, (4.33±0.17)×109, (4.72±0.15)×109, (1.42±0.02)×109 (M-1 s-1), respectively. The transient absorption spectra for the six model compounds were examined and their role as model compounds for the radiation chemistry of pharmaceuticals investigated.

  9. Radiation chemistry in the Jovian stratosphere: laboratory simulations.

    PubMed

    McDonald, G D; Thompson, W R; Sagan, C

    1992-09-01

    Low-pressure continuous-flow laboratory simulations of plasma induced chemistry in H2/He/CH4/NH3 atmospheres show radiation yields of hydrocarbons and nitrogen-containing organic compounds that increase with decreasing pressure in the range 2-200 mbar. Major products of these experiments that have been observed in the Jovian atmosphere are acetylene (C2H2), ethylene (C2H4), ethane (C2H6), hydrogen cyanide (HCN), propane (C3H8), and propyne (C3H4). Major products that have not yet been observed on Jupiter include acetonitrile (CH3CN), methylamine (CH3NH2), propene (C3H6), butane (C4H10), and butene (C4H8). Various other saturated and unsaturated hydrocarbons, as well as other amines and nitriles, are present in these experiments as minor products. We place upper limits of 10(6)-10(9) molecules cm-2 sec-1 on production rates of the major species from auroral chemistry in the Jovian stratosphere, and calculate stratospheric mole fraction contributions. This work shows that auroral processes may account for 10-100% of the total abundances of most observed organic species in the polar regions. Our experiments are consistent with models of Jovian polar stratospheric aerosol haze formation from polymerization of acetylene by secondary ultraviolet processing.

  10. Radiation chemistry of alternative fuel oxygenates -- Substituted ethers

    SciTech Connect

    Mezyk, S. P.; Cooper, W. J.; Bartels, D. M.; Tobien, T.; O'Shea, K. E.

    1999-11-15

    The electron beam process, an advanced oxidation and reduction technology, is based in the field of radiation chemistry. Fundamental to the development of treatment processes is an understanding of the underlying chemistry. The authors have previously evaluated the bimolecular rate constants for the reactions of methyl tert-butyl ether (MTBE) and with this study have extended their studies to include ethyl tert-butyl ether (ETBE), di-isopropyl ether (DIPE) and tert-amyl methyl ether (TAME) with the hydroxyl radical, hydrogen atom and solvated electron using pulse radiolysis. For all of the oxygenates the reaction with the hydroxyl radical appears to be of primary interest in the destruction of the compounds in water. The rates with the solvated electron are limiting values as the rates appear to be relatively low. The hydrogen atom rate constants are relatively low, coupled with the low yield in radiolysis, they concluded that these are of little significance in the destruction of the alternative fuel oxygenates (and MTBE).

  11. Glycoconjugates of Quinolines: Application in Medicinal Chemistry.

    PubMed

    Oliveri, Valentina; Vecchio, Graziella

    2016-09-02

    Compounds with the quinoline scaffold are widely investigated and offer a variety of therapeutical properties. A number of quinoline derivatives have been synthesized and among these there are glycoconjugated derivatives. Based on the interest for this family of compounds, we reviewed the different biological activities (molecular probes, antiinfective, antiproliferative, antiaggregant and antioxidant) and the potential applications in medicinal chemistry of quinoline glycoconjugates. This review wants to show an example of the glycoconjugation strategy which arose not only to modify the water solubility of the quinolines but also to influence their activity and targeting properties.

  12. Radiation biodosimetry: Applications for spaceflight

    NASA Astrophysics Data System (ADS)

    Blakely, W. F.; Miller, A. C.; Grace, M. B.; McLeland, C. B.; Luo, L.; Muderhwa, J. M.; Miner, V. L.; Prasanna, P. G. S.

    The multiparametric dosimetry system that we are developing for medical radiological defense applications could be adapted for spaceflight environments. The system complements the internationally accepted personnel dosimeters and cytogenetic analysis of chromosome aberrations, considered the best means of documenting radiation doses for health records. Our system consists of a portable hematology analyzer, molecular biodosimetry using nucleic acid and antigen-based diagnostic equipment, and a dose assessment management software application. A dry-capillary tube reagent-based centrifuge blood cell counter (QBC Autoread Plus, Beckon Dickinson Bioscience) measures peripheral blood lymphocytes and monocytes, which could determine radiation dose based on the kinetics of blood cell depletion. Molecular biomarkers for ionizing radiation exposure (gene expression changes, blood proteins) can be measured in real time using such diagnostic detection technologies as miniaturized nucleic acid sequences and antigen-based biosensors, but they require validation of dose-dependent targets and development of optimized protocols and analysis systems. The Biodosimetry Assessment Tool, a software application, calculates radiation dose based on a patient's physical signs and symptoms and blood cell count analysis. It also annotates location of personnel dosimeters, displays a summary of a patient's dosimetric information to healthcare professionals, and archives the data for further use. These radiation assessment diagnostic technologies can have dual-use applications supporting general medical-related care.

  13. US Reanalysis for Climate and Chemistry Applications

    NASA Technical Reports Server (NTRS)

    Rood, Richard B.; Atlas, Robert M. (Technical Monitor)

    2001-01-01

    The Data Assimilation Office will perform a short reanalysis with its next-generation data assimilation system. This reanalysis will start a few months prior to the eruption of El Chichon and continue to real time. It will cover the entire time span of the Upper Atmospheric Research Satellite mission, and it is expected to be used in chemistry and climate applications. The sorts of improvements that are expected with this system and the status will be presented. In addition there has been a call in the United States for a National Reanalysis Project. This is envisioned as a sustained multi-agency activity coordinated (staggered) with the ECMWF reanalysis. The plans for the National Reanalysis Project will be discussed.

  14. Step-by-Step Simulation of Radiation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    The irradiation of biological systems leads to the formation of radiolytic species such as H(raised dot), (raised dot)OH, H2, H2O2, e(sup -)(sub aq), etc.[1]. These species react with neighboring molecules, which result in damage in biological molecules such as DNA. Radiation chemistry is there for every important to understand the radiobiological consequences of radiation[2]. In this work, we discuss an approach based on the exact Green Functions for diffusion-influenced reactions which may be used to simulate radiation chemistry and eventually extended to study more complex systems, including DNA.

  15. Strontium: Part II. Chemistry, Biological Aspects and Applications.

    ERIC Educational Resources Information Center

    Britton, G. C.; Johnson, C. H.

    1987-01-01

    Reviews basic information on the Chemistry of strontium and its compounds. Explains biological aspects of strontium and its pharmaceutical applications. Highlights industrial application of strontium and its components. (ML)

  16. Modeling Interactions Among Turbulence, Gas-Phase Chemistry, Soot and Radiation Using Transported PDF Methods

    NASA Astrophysics Data System (ADS)

    Haworth, Daniel

    2013-11-01

    The importance of explicitly accounting for the effects of unresolved turbulent fluctuations in Reynolds-averaged and large-eddy simulations of chemically reacting turbulent flows is increasingly recognized. Transported probability density function (PDF) methods have emerged as one of the most promising modeling approaches for this purpose. In particular, PDF methods provide an elegant and effective resolution to the closure problems that arise from averaging or filtering terms that correspond to nonlinear point processes, including chemical reaction source terms and radiative emission. PDF methods traditionally have been associated with studies of turbulence-chemistry interactions in laboratory-scale, atmospheric-pressure, nonluminous, statistically stationary nonpremixed turbulent flames; and Lagrangian particle-based Monte Carlo numerical algorithms have been the predominant method for solving modeled PDF transport equations. Recent advances and trends in PDF methods are reviewed and discussed. These include advances in particle-based algorithms, alternatives to particle-based algorithms (e.g., Eulerian field methods), treatment of combustion regimes beyond low-to-moderate-Damköhler-number nonpremixed systems (e.g., premixed flamelets), extensions to include radiation heat transfer and multiphase systems (e.g., soot and fuel sprays), and the use of PDF methods as the basis for subfilter-scale modeling in large-eddy simulation. Examples are provided that illustrate the utility and effectiveness of PDF methods for physics discovery and for applications to practical combustion systems. These include comparisons of results obtained using the PDF method with those from models that neglect unresolved turbulent fluctuations in composition and temperature in the averaged or filtered chemical source terms and/or the radiation heat transfer source terms. In this way, the effects of turbulence-chemistry-radiation interactions can be isolated and quantified.

  17. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1994-01-01

    wave precursor ahead of vehicles entering the Earth's atmosphere. (8) Since considerable data exists for radiating nonequilibrium flow behind normal shock waves, a normal shock wave version of the blunt body code was developed. (9) By comparing predictions from the models and codes with available normal shock data and the flight data of Fire II, it is believed that the developed flowfield and nonequilibrium radiation models have been essentially validated for engineering applications.

  18. Applications of click chemistry in radiopharmaceutical development.

    PubMed

    Walsh, Joseph C; Kolb, Hartmuth C

    2010-01-01

    Click chemistry, a concept that employs only practical and reliable transformations for compound synthesis, has made a significant impact in several areas of chemistry, including material sciences and drug discovery. The present article describes the use of click chemistry for the development of radiopharmaceuticals. Target templated in situ click chemistry was used for lead generation. The 1,2,3-triazole moiety was found to improve the pharmacokinetic properties of certain radiopharmaceuticals. The reliable Cu(I)-catalyzed click reaction was employed for radiolabeling of peptidic compounds without the need for protecting groups. In summary, the click chemistry approach for the discovery, optimization and labeling of new radiotracers, represents a very powerful tool for radiopharmaceutical development.

  19. Active Learning Applications in the History of Chemistry: Pre-Service Chemistry Teachers' Level of Knowledge and Views

    ERIC Educational Resources Information Center

    Sendur, Gülten; Polat, Merve; Toku, Abdullah; Kazanci, Coskun

    2014-01-01

    This study aims to investigate the effects of a History and Philosophy of Chemistry-I course based on active learning applications on the level of knowledge of pre-service chemistry teachers about the history of chemistry. The views of pre-service chemistry teachers about these activities were also investigated. The study was carried out with 38…

  20. Fluorine Compounds and Dental Health: Applications of General Chemistry Topics

    ERIC Educational Resources Information Center

    Pinto, Gabriel

    2009-01-01

    An example about the use of everyday phenomena in teaching general chemistry is given. Students have a greater appreciation of the principles of chemistry if they can see the relevance to their lives. Fluorine compounds in dental applications (as topical or as systemic use) provide an excellent context in which to review core content of general…

  1. Calibration services for medical applications of radiation

    SciTech Connect

    DeWerd, L.A.

    1993-12-31

    Calibration services for the medical community applications of radiation involve measuring radiation precisely and having traceability to the National Institute of Standards and Technology (NIST). Radiation therapy applications involve the use of ionization chambers and electrometers for external beams and well-type ionization chamber systems as well as radioactive sources for brachytherapy. Diagnostic x-ray applications involve ionization chamber systems and devices to measure other parameters of the x-ray machine, such as non-invasive kVp meters. Calibration laboratories have been established to provide radiation calibration services while maintaining traceability to NIST. New radiation applications of the medical community spur investigation to provide the future calibration needs.

  2. Density Functionals with Broad Applicability in Chemistry

    SciTech Connect

    Zhao, Yan; Truhlar, Donald G.

    2008-02-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Although density functional theory is widely used in the computational chemistry community, the most popular density functional, B3LYP, has some serious shortcomings: (i) it is better for main-group chemistry than for transition metals; (ii) it systematically underestimates reaction barrier heights; (iii) it is inaccurate for interactions dominated by mediumrange correlation energy, such as van der Waals attraction, aromatic-aromatic stacking, and alkane isomerization energies. We have developed a variety of databases for testing and designing new density functionals. We used these data to design new density functionals, called M06-class (and, earlier, M05-class) functionals, for which we enforced some fundamental exact constraints such as the uniform-electron-gas limit and the absence of self-correlation energy. Our M06-class functionals depend on spin-up and spin-down electron densities (i.e., spin densities), spin density gradients, spin kinetic energy densities, and, for nonlocal (also called hybrid) functionals, Hartree-Fock exchange. We have developed four new functionals that overcome the above-mentioned difficulties: (a) M06, a hybrid meta functional, is a functional with good accuracy “across-theboard” for transition metals, main group thermochemistry, medium-range correlation energy, and barrier heights; (b) M06- 2X, another hybrid meta functional, is not good for transition metals but has excellent performance for main group chemistry, predicts accurate valence and Rydberg electronic excitation energies, and is an excellent functional for aromatic-aromatic stacking interactions; (c) M06-L is not as accurate as M06 for barrier heights but is the most accurate

  3. Fire risk, atmospheric chemistry and radiative forcing assessment of wildfires in eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Athanasopoulou, E.; Rieger, D.; Walter, C.; Vogel, H.; Karali, A.; Hatzaki, M.; Gerasopoulos, E.; Vogel, B.; Giannakopoulos, C.; Gratsea, M.; Roussos, A.

    2014-10-01

    The current research study aims at investigating the atmospheric implications of a major fire event in the Mediterranean area. For this purpose, a regional aerosol model coupled online with meteorology (COSMO-ART) is applied over Greece during late summer 2007. Fire risk model results proved to be adequate in reproducing the highly destructive event, which supports further applications for national meteorological forecasts and early warning systems for fire prevention. Columnar aerosol loading field predictions are consistent with satellite maps, which further allows for the correlation of this wildfire event to the atmospheric chemistry and the radiative forcing. Gaseous chemistry resembles that in urban environments and led to nitrogen dioxide and ozone exceedances in several cities in proximity to and downwind the fire spots, respectively. Influence in Athens is found significant from the Euboean plume (45% of total surface PM10) and small (5%) from the fires in Peloponnese. Fire events are indicated by sharp increases in organic to elemental carbon (6), together with sharp decreases in secondary to total organic components (0.1), in comparison to their values during the pre- and post-fire period over Athens (1 and 0.6, respectively). The change in the radiative budget induced by the fire plume is found negative (3-day-average value up to -10 W m-2). Direct heat input is found negligible, thus the net temperature effect is also negative over land (-0.5 K). Nevertheless, positive temperature changes are found overseas (hourly value up to +2 K), due to the amplified radiation absorption by aged soot, coupled to the intense stabilization of the atmosphere above the sea surface.

  4. Decoration of silk fibroin by click chemistry for biomedical application.

    PubMed

    Zhao, Hongshi; Heusler, Eva; Jones, Gabriel; Li, Linhao; Werner, Vera; Germershaus, Oliver; Ritzer, Jennifer; Luehmann, Tessa; Meinel, Lorenz

    2014-06-01

    Silkfibroin (SF) has an excellent biocompatibility and its remarkable structure translates into exciting mechanical properties rendering this biomaterial particularly fascinating for biomedical application. To further boost the material's biological/preclinical impact, SF is decorated with biologics, typically by carbodiimide/N-hydroxysuccinimide coupling (EDC/NHS). For biomedical application, this chemistry challenges the product risk profile due to the formation of covalent aggregates, particularly when decoration is with biologics occurring naturally in humans as these aggregates may prime for autoimmunity. Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC; click chemistry) provides the necessary specificity to avoid such intermolecular, covalent aggregates. We present a blueprint outlining the necessary chemistry rendering SF compatible with CuAAC and with a particular focus on structural consequences. For that, the number of SF carboxyl groups (carboxyl-SF; required for EDC/NHS chemistry) or azido groups (azido-SF; required for click chemistry) was tailored by means of diazonium coupling of the SF tyrosine residues. Structural impact on SF and decorated SF was characterized by Fourier transform infrared spectroscopy (FTIR). The click chemistry yielded a better controlled product as compared to the EDC/NHS chemistry with no formation of inter- and intramolecular crosslinks as demonstrated for SF decorated with fluorescent model compounds or a biologic, fibroblast growth factor 2 (FGF2), respectively. In conclusion, SF can readily be translated into a scaffold compatible with click chemistry yielding decorated products with a better risk profile for biomedical application.

  5. The vertical distribution of ozone instantaneous radiative forcing from satellite and chemistry climate models

    NASA Astrophysics Data System (ADS)

    Aghedo, A. M.; Bowman, K. W.; Worden, H. M.; Kulawik, S. S.; Shindell, D. T.; Lamarque, J. F.; Faluvegi, G.; Parrington, M.; Jones, D. B. A.; Rast, S.

    2011-01-01

    We evaluate the instantaneous radiative forcing (IRF) of tropospheric ozone predicted by four state-of-the-art global chemistry climate models (AM2-Chem, CAM-Chem, ECHAM5-MOZ, and GISS-PUCCINI) against ozone distribution observed from the NASA Tropospheric Emission Spectrometer (TES) during August 2006. The IRF is computed through the application of an observationally constrained instantaneous radiative forcing kernels (IRFK) to the difference between TES and model-predicted ozone. The IRFK represent the sensitivity of outgoing longwave radiation to the vertical and spatial distribution of ozone under all-sky condition. Through this technique, we find total tropospheric IRF biases from -0.4 to + 0.7 W/m2 over large regions within the tropics and midlatitudes, due to ozone differences over the region in the lower and middle troposphere, enhanced by persistent bias in the upper troposphere-lower stratospheric region. The zonal mean biases also range from -30 to +50 mW/m2 for the models. However, the ensemble mean total tropospheric IRF bias is less than 0.2 W/m2 within the entire troposphere.

  6. The Application of Physical Organic Chemistry to Biochemical Problems.

    ERIC Educational Resources Information Center

    Westheimer, Frank

    1986-01-01

    Presents the synthesis of the science of enzymology from application of the concepts of physical organic chemistry from a historical perspective. Summarizes enzyme and coenzyme mechanisms elucidated prior to 1963. (JM)

  7. The use of the R language for medicinal chemistry applications.

    PubMed

    Mente, Scot; Kuhn, Max

    2012-01-01

    This manuscript serves as a review of how the R language has been used in the last decade to address problems related to medicinal chemistry design. This includes the use of the R language for chemoinformatics applications and interfaces, as well as statistical modeling for ADMET and potency endpoints. Additionally, a few examples of R code are provided to demonstrate the ability of this language to make available cutting-edge statistical analysis to the medicinal chemistry design community.

  8. Synchrotron radiation applications in medical research

    SciTech Connect

    Thomlinson, W.

    1997-08-01

    Over the past two decades there has been a phenomenal growth in the number of dedicated synchrotron radiation facilities and a corresponding growth in the number of applications in both basic and applied sciences. The high flux and brightness, tunable beams, time structure and polarization of synchrotron radiation provide an ideal x- ray source for many applications in the medical sciences. There is a dual aspect to the field of medical applications of synchrotron radiation. First there are the important in-vitro programs such as structural biology, x-ray microscopy, and radiation cell biology. Second there are the programs that are ultimately targeted at in-vivo applications. The present status of synchrotron coronary angiography, bronchography, multiple energy computed tomography, mammography and radiation therapy programs at laboratories around the world is reviewed.

  9. Therapeutic Applications of Ionizing Radiations

    NASA Astrophysics Data System (ADS)

    Sánchez-Santos, María Elena

    The aim of radiation therapy is to deliver a precisely measured dose of radiation to a defined tumour volume with minimal damage to the surrounding healthy tissue, resulting in the eradication of the tumour, a higher quality of life with palliation of symptoms of the disease, and the prolongation of survival at competitive cost. Together with surgery and pharmacology, radiotherapy is presently one of the most important therapeutical weapons against cancer. This chapter provides an overview of the clinical use of radiation, with emphasis on the optimisation of treatment planning and delivery, and a top level summary of state-of-the-art techniques in radiation therapy.

  10. Applications of polydimethylsiloxane in analytical chemistry: a review.

    PubMed

    Seethapathy, Suresh; Górecki, Tadeusz

    2012-10-31

    Silicones have innumerable applications in many areas of life. Polydimethylsiloxane (PDMS), which belongs to the class of silicones, has been extensively used in the field of analytical chemistry owing to its favourable physicochemical properties. The use of PDMS in analytical chemistry gained importance with its application as a stationary phase in gas chromatographic separations. Since then it has been used in many sample preparation techniques such as solid phase microextraction (SPME), stir bar sorptive extraction (SBSE), thin-film extraction, permeation passive sampling, etc. Further, it is gaining importance in the manufacturing of lab-on-a-chip devices, which have revolutionized bio-analysis. Applications of devices containing PDMS and used in the field of analytical chemistry are reviewed in this paper.

  11. Step-by-Step Simulation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Cucinotta, Francis A.

    2011-01-01

    Radiolytic species are formed approximately 1 ps after the passage of ionizing radiation through matter. After their formation, they diffuse and chemically react with other radiolytic species and neighboring biological molecules, leading to various oxidative damage. Therefore, the simulation of radiation chemistry is of considerable importance to understand how radiolytic species damage biological molecules [1]. The step-by-step simulation of chemical reactions is difficult, because the radiolytic species are distributed non-homogeneously in the medium. Consequently, computational approaches based on Green functions for diffusion-influenced reactions should be used [2]. Recently, Green functions for more complex type of reactions have been published [3-4]. We have developed exact random variate generators of these Green functions [5], which will allow us to use them in radiation chemistry codes. Moreover, simulating chemistry using the Green functions is which is computationally very demanding, because the probabilities of reactions between each pair of particles should be evaluated at each timestep [2]. This kind of problem is well adapted for General Purpose Graphic Processing Units (GPGPU), which can handle a large number of similar calculations simultaneously. These new developments will allow us to include more complex reactions in chemistry codes, and to improve the calculation time. This code should be of importance to link radiation track structure simulations and DNA damage models.

  12. Applications of radiation belt research

    NASA Astrophysics Data System (ADS)

    Lanzerotti, Louis J.

    2011-10-01

    When Arthur Clark and John Pierce proposed geosynchronous and low-Earth-orbiting (GEO and LEO) communications satellites, respectively, they did not envision that the environment in which their concepts would fly would be anything but benign. Discovery of the Van Allen radiation belts in 1958 fundamentally altered understanding of Earth's near-space environment and its impacts on technologies. Indeed, the first commercial telecommunications satellite, Telstar 1, in LEO, failed some 6 months after launch (10 July 1962) due to trapped radiation that had been enhanced from the Starfish Prime high-altitude nuclear test on the day prior to launch. Today radiation trapped in the geomagnetic field, as well as solar energetic particles that can access the magnetosphere, forms critical constraints on the design and operations of satellite systems. These considerations were important factors in the planning of the AGU Chapman Conference on radiation belts that was hosted in July 2011 by the Memorial University of Newfoundland in St. John's, Canada (see "Chapman Conference on Radiation Belts and the Inner Magnetosphere," page 4). The conference presentations, discussions, and hallway conversations illuminated current understanding of Earth's radiation belts and critical issues remaining. Certainly, fundamental understanding of radiation belt origins remains elusive. The relative roles of adiabatic processes, geomagnetic storm injections, and wave heating, among other considerations, are central topics of intense debate and of competing modeling regimes by numerous active groups.

  13. Chemistry and radiative shielding in star-forming galactic discs

    NASA Astrophysics Data System (ADS)

    Safranek-Shrader, Chalence; Krumholz, Mark R.; Kim, Chang-Goo; Ostriker, Eve C.; Klein, Richard I.; Li, Shule; McKee, Christopher F.; Stone, James M.

    2017-02-01

    To understand the conditions under which dense, molecular gas is able to form within a galaxy, we post-process a series of three-dimensional galactic-disc-scale simulations with ray-tracing-based radiative transfer and chemical network integration to compute the equilibrium chemical and thermal state of the gas. In performing these simulations, we vary a number of parameters, such as the interstellar radiation field strength, vertical scaleheight of stellar sources, and cosmic ray flux, to gauge the sensitivity of our results to these variations. Self-shielding permits significant molecular hydrogen (H2) abundances in dense filaments around the disc mid-plane, accounting for approximately ˜10-15 per cent of the total gas mass. Significant CO fractions only form in the densest, nH≳ 10^3 cm^{-3}, gas where a combination of dust, H2, and self-shielding attenuates the far-ultraviolet background. We additionally compare these ray-tracing-based solutions to photochemistry with complementary models where photoshielding is accounted for with locally computed prescriptions. With some exceptions, these local models for the radiative shielding length perform reasonably well at reproducing the distribution and amount of molecular gas as compared with a detailed, global ray-tracing calculation. Specifically, an approach based on the Jeans length with a T = 40 K temperature cap performs the best in regard to a number of different quantitative measures based on the H2 and CO abundances.

  14. Applications of asymmetric organocatalysis in medicinal chemistry.

    PubMed

    Alemán, José; Cabrera, Silvia

    2013-01-21

    In the last decade, organocatalysis, the use of small chiral organic molecules as catalysts, has proven to be a valuable and attractive tool for the synthesis of enantiomerically enriched molecules. A number of organocatalysts and processes, such as one-pot, tandem, cascade or multicomponent reactions, have been reported to date. Furthermore, the many advantages of organocatalysis - robust, non-toxic, affordable, inert atmosphere, easy reaction manipulation, etc. - allow the preparation of bioactive compounds using simple and metal-free procedures, thus avoiding false positives in the biological evaluation. This mini-review focuses on medicinal chemistry programs that have synthesized biologically active compounds using one or more organocatalytic steps. In this respect, the potential of organocatalytic methods for enabling the chemical synthesis of important medicinal targets will be highlighted.

  15. Applications of azide-based bioorthogonal click chemistry in glycobiology.

    PubMed

    Zhang, Xiu; Zhang, Yan

    2013-06-19

    Click chemistry is a powerful chemical reaction with excellent bioorthogonality features: biocompatible, rapid and highly specific in biological environments. For glycobiology, bioorthogonal click chemistry has created a new method for glycan non-invasive imaging in living systems, selective metabolic engineering, and offered an elite chemical handle for biological manipulation and glycomics studies. Especially the [3 + 2] dipolar cycloadditions of azides with strained alkynes and the Staudinger ligation of azides and triarylphosphines have been widely used among the extant click reactions. This review focuses on the azide-based bioorthogonal click chemistry, describing the characteristics and development of these reactions, introducing some recent applications in glycobiology research, especially in glycan metabolic engineering, including glycan non-invasive imaging, glycomics studies and viral surface manipulation for drug discovery as well as other applications like activity-based protein profiling and carbohydrate microarrays.

  16. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1993-01-01

    The period from Jan. 1993 thru Aug. 1993 is covered. The primary tasks during this period were the development of a single and multi-vibrational temperature preferential vibration-dissociation coupling model, the development of a normal shock nonequilibrium radiation-gasdynamic coupling model based upon the blunt body model, and the comparison of results obtained with these models with experimental data. In addition, an extensive series of computations were conducted using the blunt body model to develop a set of reference results covering a wide range of vehicle sizes, altitudes, and entry velocities.

  17. Radiation chemistry of salt-mine brines and hydrates. [Gamma radiation

    SciTech Connect

    Jenks, G.H.; Walton, J.R.; Bronstein, H.R.; Baes, C.F. Jr.

    1981-07-01

    Certain aspects of the radiation chemistry of NaCl-saturated MgCl/sub 2/ solutions and MgCl/sub 2/ hydrates at temperatures in the range of 30 to 180/sup 0/C were investigated through experiments. A principal objective was to establish the values for the yields of H/sub 2/ (G(H/sub 2/)) and accompanying oxidants in the gamma-ray radiolysis of concentrated brines that might occur in waste repositories in salt. We concluded that G(H/sub 2/) from gamma-irradiated brine solution into a simultaneously irradiated, deaerated atmosphere above the solution is between 0.48 and 0.49 over most of the range 30 to 143/sup 0/C. The yield is probably somewhat lower at the lower end of this range, averaging 0.44 at 30 to 45/sup 0/C. Changes in the relative amounts of MgCl/sub 2/ and NaCl in the NaCl-saturated solutions have negligible effects on the yield. The yield of O/sub 2/ into the same atmosphere averages 0.13, independent of the temperature and brine composition, showing that only about 50% of the radiolytic oxidant that was formed along with the H/sub 2/ was present as O/sub 2/. We did not identify the species that compose the remainder of the oxidant. We concluded that the yield of H/sub 2/ from a gamma-irradiated brine solution into a simultaneously irradiated atmosphere containing 5 to 8% air in He may be greater than the yield in deaerated systems by amounts ranging from 0% for temperatures of 73 to 85/sup 0/C, to about 30 and 40% for temperatures in the ranges 100 to 143/sup 0/C and 30 to 45/sup 0/C, respectively. We did not establish the mechanism whereby the air affected the yields of H/sub 2/ and O/sub 2/. The values found in this work for G(H/sub 2/) in deaerated systems are in approximate agreement with the value of 0.44 for the gamma-irradiation yield of H/sub 2/ in pure H/sub 2/O at room temperature. They are also in agreement with the values predicted by extrapolation from the findings of previous researchers for the value for G(H/sub 2/) in 2 M NaCl solutions

  18. Medical Applications of Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Prezado, Yolanda; Martínez-Rovira, Immaculada

    This chapter describes the state-of-art of synchrotron radiation therapies in the treatment of radioresistant tumors. The tolerance of the surrounding healthy tissue severely limits the achievement of a curative treatment for some brain tumors, like gliomas. This restriction is especially important in children, due to the high risk of complications in the development of the central nervous system. In addition, the treatment of tumors close to an organ at risk, like the spinal cord, is also restrained. One possible solution is the development of new radiotherapy techniques would exploit radically different irradiation modes, as it is the case of synchrotron radiotherapies. Their distinct features allow to modify the biological equivalent doses. In this chapter the three new approaches under development at the European Synchrotron Radiation Facility (ESRF), in Grenoble (France), will be described, namely: stereotactic synchrotron radiation therapy, microbeam radiation therapy and minibeam radiation therapy. The promising results obtained in the treatment of high grade brain tumors in preclinical studies have paved the way to the forthcoming clinical trials, currently in preparation.

  19. Observational constraints on ozone radiative forcing from the Atmospheric Chemistry Climate Model Intercomparison Project (ACCMIP)

    NASA Astrophysics Data System (ADS)

    Bowman, K.; Shindell, D.; Worden, H.; Lamarque, J. F.; Young, P. J.; Stevenson, D.; Qu, Z.; de la Torre, M.; Bergmann, D.; Cameron-Smith, P.; Collins, W. J.; Doherty, R.; Dalsøren, S.; Faluvegi, G.; Folberth, G.; Horowitz, L. W.; Josse, B.; Lee, Y. H.; MacKenzie, I.; Myhre, G.; Nagashima, T.; Naik, V.; Plummer, D.; Rumbold, S.; Skeie, R.; Strode, S.; Sudo, K.; Szopa, S.; Voulgarakis, A.; Zeng, G.; Kulawik, S.; Worden, J.

    2012-09-01

    We use simultaneous observations of ozone and outgoing longwave radiation (OLR) from the Tropospheric Emission Spectrometer (TES) to evaluate ozone distributions and radiative forcing simulated by a suite of chemistry-climate models that participated in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The ensemble mean of ACCMIP models show a persistent but modest tropospheric ozone low bias (5-20 ppb) in the Southern Hemisphere (SH) and modest high bias (5-10 ppb) in the Northern Hemisphere (NH) relative to TES for 2005-2010. These biases lead to substantial differences in ozone instantaneous radiative forcing between TES and the ACCMIP simulations. Using TES instantaneous radiative kernels (IRK), we show that the ACCMIP ensemble mean has a low bias in the SH tropics of up to 100 m W m-2 locally and a global low bias of 35 ± 44 m W m-2 relative to TES. Combining ACCMIP preindustrial ozone and the TES present-day ozone, we calculate an observationally constrained estimate of tropospheric ozone radiative forcing (RF) of 399 ± 70 m W m-2, which is about 7% higher than using the ACCMIP models alone but with the same standard deviation (Stevenson et al., 2012). In addition, we explore an alternate approach to constraining radiative forcing estimates by choosing a subset of models that best match TES ozone, which leads to an ozone RF of 369 ± 42 m W m-2. This estimate is closer to the ACCMIP ensemble mean RF but about a 40% reduction in standard deviation. These results point towards a profitable direction of combining observations and chemistry-climate model simulations to reduce uncertainty in ozone radiative forcing.

  20. Applications of Fluorine in Medicinal Chemistry.

    PubMed

    Gillis, Eric P; Eastman, Kyle J; Hill, Matthew D; Donnelly, David J; Meanwell, Nicholas A

    2015-11-12

    The role of fluorine in drug design and development is expanding rapidly as we learn more about the unique properties associated with this unusual element and how to deploy it with greater sophistication. The judicious introduction of fluorine into a molecule can productively influence conformation, pKa, intrinsic potency, membrane permeability, metabolic pathways, and pharmacokinetic properties. In addition, (18)F has been established as a useful positron emitting isotope for use with in vivo imaging technology that potentially has extensive application in drug discovery and development, often limited only by convenient synthetic accessibility to labeled compounds. The wide ranging applications of fluorine in drug design are providing a strong stimulus for the development of new synthetic methodologies that allow more facile access to a wide range of fluorinated compounds. In this review, we provide an update on the effects of the strategic incorporation of fluorine in drug molecules and applications in positron emission tomography.

  1. Ab initio quantum chemistry: Methodology and applications

    PubMed Central

    Friesner, Richard A.

    2005-01-01

    This Perspective provides an overview of state-of-the-art ab initio quantum chemical methodology and applications. The methods that are discussed include coupled cluster theory, localized second-order Moller–Plesset perturbation theory, multireference perturbation approaches, and density functional theory. The accuracy of each approach for key chemical properties is summarized, and the computational performance is analyzed, emphasizing significant advances in algorithms and implementation over the past decade. Incorporation of a condensed-phase environment by means of mixed quantum mechanical/molecular mechanics or self-consistent reaction field techniques, is presented. A wide range of illustrative applications, focusing on materials science and biology, are discussed briefly. PMID:15870212

  2. Astrobiological Aspects of Radiation Chemistry in Europa's Icy Regolith

    NASA Astrophysics Data System (ADS)

    Carlson, R. W.; Hand, K. P.

    2006-05-01

    Jupiter's moon Europa, with its likely subsurface ocean and young, active surface, is a promising habitat for life. Europa orbits in the heart of Jupiter's powerful magnetosphere and suffers intense energetic particle bombardment, producing both positive and negative aspects for astrobiology at Europa. Ionizing radiation can produce oxidants that could support a radiation-driven ecology as proposed by Chyba. On the other hand, biomolecular evidence for life that may be upwelled to the surface is rapidly altered by irradiation, complicating astrobiological searches for evidence of life. We present an overview of laboratory work performed at JPL and elsewhere and observational results related to these two aspects. The oxidants hydrogen peroxide and molecular oxygen are known to exist on Europa and the radiolytic production of these species has been studied in the laboratory for both electron and ion irradiation. Laboratory- measured equilibrium concentrations of H2O2, where production and destruction rates are equal, are in general agreement with the observed 0.1% molar abundance on Europa. The shape of Europa's peroxide band is consistent with the line shapes observed in radiolysis and with H2O2 dispersed in water ice rather than occurring as H2O2 aggregates. Surprisingly, molecular oxygen may be even more abundant on Europa even though O2 is extremely volatile ande would be expected to escape from the ice surface. Radiolysis can produce molecular oxygen and appears to simultaneously alter the ice matrix, trapping the O2. Other species observed on Europa are CO2 and SO2, and laboratory radiolysis of these species in H2O ice produces carbonic and sulfuric acid, respectively. We are studying the radiolytic degradation of biomarkers in ice at Europa temperatures by studying both simple organics and more complex biomolecules, including microorganisms. Hydrocarbon radiolysis yields carbon dioxide and methane, which can escape the system and results in loss of carbon. In

  3. Photoreconfigurable polymers for biomedical applications: chemistry and macromolecular engineering.

    PubMed

    Zhu, Congcong; Ninh, Chi; Bettinger, Christopher J

    2014-10-13

    Stimuli-responsive polymers play an important role in many biomedical technologies. Light responsive polymers are particularly desirable because the parameters of irradiated light and diverse photoactive chemistries produce a large number of combinations between functional materials and associated stimuli. This Review summarizes recent advances in utilizing photoactive chemistries in macromolecules for prospective use in biomedical applications. Special focus is granted to selection criterion when choosing photofunctional groups. Synthetic strategies to incorporate these functionalities into polymers and networks with different topologies are also highlighted herein. Prospective applications of these materials are discussed including programmable matrices for controlled release, dynamic scaffolds for tissue engineering, and functional coatings for medical devices. The article concludes by summarizing the state of the art in photoresponsive polymers for biomedical applications including current challenges and future opportunities.

  4. A new model of the chemistry of ionizing radiation in solids: CIRIS.

    PubMed

    Shingledecker, Christopher N; Le Gal, Romane; Herbst, Eric

    2017-04-13

    The collisions between high-energy ions and solids can result in significant physical and chemical changes to the material. These effects are potentially important for better understanding the chemistry of interstellar and planetary bodies, which are exposed to cosmic radiation and the solar wind, respectively; however, modeling such collisions on a detailed microscopic basis has thus far been largely unsuccessful. To that end, a new model, entitled CIRIS: the Chemistry of Ionizing Radiation in Solids, was created to calculate the physical and chemical effects of the irradiation of solid materials. With the new code, we simulate O2 ice irradiated with 100 keV protons. Our models are able to reproduce the measured ozone abundances of a previous experimental study, as well as independently predict the approximate thickness of the ice used in that work.

  5. Quantum kernel applications in medicinal chemistry.

    PubMed

    Huang, Lulu; Massa, Lou

    2012-07-01

    Progress in the quantum mechanics of biological molecules is being driven by computational advances. The notion of quantum kernels can be introduced to simplify the formalism of quantum mechanics, making it especially suitable for parallel computation of very large biological molecules. The essential idea is to mathematically break large biological molecules into smaller kernels that are calculationally tractable, and then to represent the full molecule by a summation over the kernels. The accuracy of the kernel energy method (KEM) is shown by systematic application to a great variety of molecular types found in biology. These include peptides, proteins, DNA and RNA. Examples are given that explore the KEM across a variety of chemical models, and to the outer limits of energy accuracy and molecular size. KEM represents an advance in quantum biology applicable to problems in medicine and drug design.

  6. Response of the AMOC to reduced solar radiation - the modulating role of atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Muthers, Stefan; Raible, Christoph C.; Rozanov, Eugene; Stocker, Thomas F.

    2016-11-01

    The influence of reduced solar forcing (grand solar minimum or geoengineering scenarios like solar radiation management) on the Atlantic Meridional Overturning Circulation (AMOC) is assessed in an ensemble of atmosphere-ocean-chemistry-climate model simulations. Ensemble sensitivity simulations are performed with and without interactive chemistry. In both experiments the AMOC is intensified in the course of the solar radiation reduction, which is attributed to the thermal effect of the solar forcing: reduced sea surface temperatures and enhanced sea ice formation increase the density of the upper ocean in the North Atlantic and intensify the deepwater formation. Furthermore, a second, dynamical effect on the AMOC is identified driven by the stratospheric cooling in response to the reduced solar forcing. The cooling is strongest in the tropics and leads to a weakening of the northern polar vortex. By stratosphere-troposphere interactions, the stratospheric circulation anomalies induce a negative phase of the Arctic Oscillation in the troposphere which is found to weaken the AMOC through wind stress and heat flux anomalies in the North Atlantic. The dynamic mechanism is present in both ensemble experiments. In the experiment with interactive chemistry, however, it is strongly amplified by stratospheric ozone changes. In the coupled system, both effects counteract and weaken the response of the AMOC to the solar forcing reduction. Neglecting chemistry-climate interactions in model simulations may therefore lead to an overestimation of the AMOC response to solar forcing.

  7. Measurement and Applications of Radiation Pressure

    NASA Astrophysics Data System (ADS)

    Ma, Dakang; Garrett, Joseph; Murray, Joseph; Munday, Jeremy; Munday Lab Team

    Light reflected off a material or absorbed within it exerts radiation pressure through the transfer of momentum. Measuring and utilizing radiation pressure have aroused growing interest in a wide spectrum of research fields. Micromechanical transducers and oscillators are good candidates for measuring radiation pressure, but accompanying photothermal effects often obscure the measurement. In this work, we investigate the accurate measurement of the radiation force on microcantilevers in ambient conditions and ways to separate radiation pressure and photothermal effects. Further, we investigate an optically broadband switchable device based on polymer dispersed liquid crystal which has potential applications in solar sails and maneuvering spacecraft without moving parts. The authors would like to thank NASA Early Career Faculty Award and NASA Smallsat Technology Partnership Award for their funding support.

  8. Cephalopod ink: production, chemistry, functions and applications.

    PubMed

    Derby, Charles D

    2014-05-12

    One of the most distinctive and defining features of coleoid cephalopods-squid, cuttlefish and octopus-is their inking behavior. Their ink, which is blackened by melanin, but also contains other constituents, has been used by humans in various ways for millennia. This review summarizes our current knowledge of cephalopod ink. Topics include: (1) the production of ink, including the functional organization of the ink sac and funnel organ that produce it; (2) the chemical components of ink, with a focus on the best known of these-melanin and the biochemical pathways involved in its production; (3) the neuroecology of the use of ink in predator-prey interactions by cephalopods in their natural environment; and (4) the use of cephalopod ink by humans, including in the development of drugs for biomedical applications and other chemicals for industrial and other commercial applications. As is hopefully evident from this review, much is known about cephalopod ink and inking, yet more striking is how little we know. Towards closing that gap, future directions in research on cephalopod inking are suggested.

  9. Cephalopod Ink: Production, Chemistry, Functions and Applications

    PubMed Central

    Derby, Charles D.

    2014-01-01

    One of the most distinctive and defining features of coleoid cephalopods—squid, cuttlefish and octopus—is their inking behavior. Their ink, which is blackened by melanin, but also contains other constituents, has been used by humans in various ways for millennia. This review summarizes our current knowledge of cephalopod ink. Topics include: (1) the production of ink, including the functional organization of the ink sac and funnel organ that produce it; (2) the chemical components of ink, with a focus on the best known of these—melanin and the biochemical pathways involved in its production; (3) the neuroecology of the use of ink in predator-prey interactions by cephalopods in their natural environment; and (4) the use of cephalopod ink by humans, including in the development of drugs for biomedical applications and other chemicals for industrial and other commercial applications. As is hopefully evident from this review, much is known about cephalopod ink and inking, yet more striking is how little we know. Towards closing that gap, future directions in research on cephalopod inking are suggested. PMID:24824020

  10. Miniature spectroscopic instrumentation: Applications to biology and chemistry

    NASA Astrophysics Data System (ADS)

    Bacon, Christina P.; Mattley, Yvette; DeFrece, Ronald

    2004-01-01

    Spectroscopy is a fundamental analytical tool utilized throughout all of the sciences. For chemistry and biology alone, there are thousands of applications. In the past two decades there have been monumental advances in the miniaturization of components used in spectrophotometric systems. The key components include detector arrays, laser diodes, and fiber optics. Currently, there are numerous commercially available miniature spectrometer systems as well as discrete components that are used by researchers in designing their own systems. A comprehensive summary of current instrumentation available for the design and development of miniaturized spectroscopy applications is described, including detectors, wavelength discriminating components, light sources, and sampling assemblies. Recommendations are made for designing spectrometer systems for specific applications. Current literature is reviewed for chemical and biological applications specifically using miniaturized spectrometer systems with the focus being on ultraviolet-visible-near-infrared spectrometers. The applications include laboratory applications, environmental sensing, on-site industrial analyses, botany and ecology applications, and finally clinical and biochemical studies. Additionally, microspectrometers, two-dimensional arrays, and photonics crystals are discussed in regards to their future role in chemistry and biology applications.

  11. CFRP radiator concept for space applications

    NASA Astrophysics Data System (ADS)

    Lindenmaier, Peter; Hartmann, Dennis; Weiß, Felix

    2016-06-01

    The paper presents the work conducted by HPS GmbH on manufacturing, analysis and testing of an innovative CFRP radiator for spacecraft applications, having the same thermal performances and a mass reduction of more than 30 % compared to standard aluminum radiators (in addition see Schlitt et al. in 40th international conference on environmental systems, 2010). The developed configuration can be used as condenser or radiation heat sink on the East/West panels of the spacecraft for either two-phase or single-phase heat transportation systems.

  12. The Chemistry and Applications of π-Gels

    NASA Astrophysics Data System (ADS)

    Ghosh, Samrat; Praveen, Vakayil K.; Ajayaghosh, Ayyappanpillai

    2016-07-01

    π-Gels are a promising class of functional soft materials formed out of short π-conjugated molecules. By utilizing the chemistry of noncovalent interactions, researchers have created a wide range of π-gels that are composed of supramolecular polymers. During the last two decades, supramolecular gel chemistry has been pursued with the hope of developing new materials for applications in, for example, organic electronics, energy harvesting, sensing, and imaging. The high expectations for π-gels were centered mainly around their electronic properties, such as tunable emission, energy transfer, electron transfer, charge transport, and electrical conductivity; such properties are amenable to modulation through size and shape control of molecular assemblies. Although a large number of exciting publications have appeared, a major technological breakthrough is yet to be realized. In this review, we analyze the recent advancements in the area of functional π-gels and their scope in future applications.

  13. Application of Multidimensional Spectrum Analysis for Analytical Chemistry

    SciTech Connect

    Hatsukawa, Yuichi; Hayakawa, Takehito; Toh, Yosuke; Shinohara, Nobuo; Oshima, Masumi

    1999-12-31

    Feasibility of application of the multidimensional {gamma} ray spectroscopy for analytical chemistry was examined. Two reference igneous rock (JP-1, JB-1a) samples issued by the Geological Survey of Japan (GSJ) were irradiated at a research reactor with thermal neutrons, and {gamma} rays from the radioisotopes produced by neutron capture reactions were measured using a {gamma}-ray detector array. Simultaneously 27 elements were observed with no chemical separation.

  14. Application of multidimensional spectrum analysis for analytical chemistry

    SciTech Connect

    Hatsukawa, Yuichi; Hayakawa, Takehito; Toh, Yosuke; Shinohara, Nobuo; Oshima, Masumi

    1999-11-16

    Feasibility of application of the multidimensional {gamma} ray spectroscopy for analytical chemistry was examined. Two reference igneous rock (JP-1, JB-1a) samples issued by the Geological Survey of Japan (GSJ) were irradiated at a research reactor with thermal neutrons, and {gamma} rays from the radioisotopes produced by neutron capture reactions were measured using a {gamma}-ray detector array. Simultaneously 27 elements were observed with no chemical separation.

  15. Some applications of thermodynamics in crystal chemistry

    NASA Astrophysics Data System (ADS)

    Herbstein, Frank H.

    1996-01-01

    The integrated study of polymorphic phase changes in crystals by combining thermodynamic and crystallographic data is illustrated for four one-component systems — tin, carbon, adamantane and fullerene C 60 Ih — of increasing complexity. A brief review of the basic thermodynamics of the solid state (laws of thermodynamics, polymorphism, order of transitions) reminds the reader that enthalpy ( H) and entropy ( S) are experimental quantities derivable from the values of the heat capacity at constant pressure ( CP) measured as a function of temperature ( T). Combination of H and S through the Gibbs function gives the free energy as a function of T ( G = H - TS). For a one-component crystal with two polymorphic forms, the separate roles of the enthalpy and entropy differences between the polymorphs can be distinguished. This is illustrated in quantitative fashion for the two polymorphs of tin at atmospheric pressure, where there is a first-order phase transformation from grey (diamond) to white (metallic) at 286 K. Application of the Clausius-Clapeyron equation ( {dP }/{dT } = {ΔS}/{ΔV}) shows that metallic tin is the stable phase above ≈ 5 kbar at 0 K. This is entirely analogous to the treatment of the pressure dependence of the melting point of ice. In the next stage, pressure is added as a variable in order to treat the graphite-diamond polymorphism of carbon. Adamantane, for which calorimetric, phase-diagram and crystallographic data are available over a considerable range of temperature and pressure, is next reviewed in detail. The polymorphic change from tetragonal (stable below 208.6 K at atmospheric pressure) to cubic is almost, but not quite, first-order in character. A somewhat similar analysis is applied to available calorimetric and crystallographic data for fullerene C60 Ih, where the transition shows appreciable deviations from ideal first-order character. The next stage, not considered here, would be to proceed from the methods of

  16. Radiation Detection for Homeland Security Applications

    NASA Astrophysics Data System (ADS)

    Ely, James

    2008-05-01

    In the past twenty years or so, there have been significant changes in the strategy and applications for homeland security. Recently there have been significant at deterring and interdicting terrorists and associated organizations. This is a shift in the normal paradigm of deterrence and surveillance of a nation and the `conventional' methods of warfare to the `unconventional' means that terrorist organizations resort to. With that shift comes the responsibility to monitor international borders for weapons of mass destruction, including radiological weapons. As a result, countries around the world are deploying radiation detection instrumentation to interdict the illegal shipment of radioactive material crossing international borders. These efforts include deployments at land, rail, air, and sea ports of entry in the US and in European and Asian countries. Radioactive signatures of concern include radiation dispersal devices (RDD), nuclear warheads, and special nuclear material (SNM). Radiation portal monitors (RPMs) are used as the main screening tool for vehicles and cargo at borders, supplemented by handheld detectors, personal radiation detectors, and x-ray imaging systems. This talk will present an overview of radiation detection equipment with emphasis on radiation portal monitors. In the US, the deployment of radiation detection equipment is being coordinated by the Domestic Nuclear Detection Office within the Department of Homeland Security, and a brief summary of the program will be covered. Challenges with current generation systems will be discussed as well as areas of investigation and opportunities for improvements. The next generation of radiation portal monitors is being produced under the Advanced Spectroscopic Portal program and will be available for deployment in the near future. Additional technologies, from commercially available to experimental, that provide additional information for radiation screening, such as density imaging equipment, will

  17. Radiation chemistry of amino acids, peptides and proteins in relation to the radiation sterilization of high-protein foods

    SciTech Connect

    Garrison, W. M.

    1981-12-01

    An important source of information on the question of whether or not toxic or other deleterious substances are formed in the radiation sterilization of foods is the chemical study of reaction products and reaction mechanisms in the radiolysis of individual food components. The present evaluation of the radiation chemistry of amino acids, peptides, and proteins outlines the various radiation-induced processes which lead to amino acid degradation and to the synthesis of amino acid derivatives of higher molecular weight. Among the latter are the ..cap alpha..,..cap alpha..'-diamino dicarboxylic acids which are formed as major products in the radiolysis of peptides both in aqueous solution and in the solid state. The ..cap alpha..,..cap alpha..'-diamino acids are of particular interest as irradiation products because they represent a class of compounds not normally encountered in plant and animal protein sources. Such compounds have, however, been isolated from certain types of bacteria and bacterial products. All of the available data strongly suggest that the ..cap alpha..,..cap alpha..'-diamino acids are produced in significant yield in the radiation sterilization of high protein foods. The importance of initiating extensive chemical and biological studies of these and of other high molecular weight products in irradiated food is emphasized.

  18. Scattered Radiation Emission Imaging: Principles and Applications

    PubMed Central

    Nguyen, M. K.; Truong, T. T.; Morvidone, M.; Zaidi, H.

    2011-01-01

    Imaging processes built on the Compton scattering effect have been under continuing investigation since it was first suggested in the 50s. However, despite many innovative contributions, there are still formidable theoretical and technical challenges to overcome. In this paper, we review the state-of-the-art principles of the so-called scattered radiation emission imaging. Basically, it consists of using the cleverly collected scattered radiation from a radiating object to reconstruct its inner structure. Image formation is based on the mathematical concept of compounded conical projection. It entails a Radon transform defined on circular cone surfaces in order to express the scattered radiation flux density on a detecting pixel. We discuss in particular invertible cases of such conical Radon transforms which form a mathematical basis for image reconstruction methods. Numerical simulations performed in two and three space dimensions speak in favor of the viability of this imaging principle and its potential applications in various fields. PMID:21747823

  19. Chemistry and application of flexible porous coordination polymers*

    PubMed Central

    Bureekaew, Sareeya; Shimomura, Satoru; Kitagawa, Susumu

    2008-01-01

    Porous coordination polymers (PCPs), which are microporous materials, have been given much attention from both scientific and commercial aspects regarding their application to gas storage, gas separation and catalytic reaction because of the regularity of their pore shape and pore size, accompanied with the functionality. Moreover, in recent years, flexible PCPs, which are structurally transformable depending upon external stimuli, have been attractive because they provide unique properties, dissimilar to those of zeolites. In this review, the chemistry and application of flexible crystalline PCPs are summarized and discussed. PMID:27877934

  20. CHEMISTRY OF A PROTOPLANETARY DISK WITH GRAIN SETTLING AND Ly{alpha} RADIATION

    SciTech Connect

    Fogel, Jeffrey K. J.; Bethell, Thomas J.; Bergin, Edwin A.; Calvet, Nuria; Semenov, Dmitry E-mail: tbethell@umich.edu E-mail: ncalvet@umich.edu

    2011-01-01

    We present results from a model of the chemical evolution of protoplanetary disks. In our models, we directly calculate the changing propagation and penetration of a high energy radiation field with Ly{alpha} radiation included. We also explore the effect on our models of including dust grain settling. We find that, in agreement with earlier studies, the evolution of dust grains plays a large role in determining how deep the UV radiation penetrates into the disk. Significant grain settling at the midplane leads to much smaller freeze-out regions and a correspondingly larger molecular layer, which leads to an increase in column density for molecular species such as CO, CN, and SO. The inclusion of Ly{alpha} radiation impacts the disk chemistry through specific species that have large photodissociation cross sections at 1216 A. These include HCN, NH{sub 3}, and CH{sub 4}, for which the column densities are decreased by an order of magnitude or more due to the presence of Ly{alpha} radiation in the UV spectrum. A few species, such as CO{sub 2} and SO, are enhanced by the presence of Ly{alpha} radiation, but rarely by more than a factor of a few.

  1. Emerging applications of radiation-modified carrageenans

    NASA Astrophysics Data System (ADS)

    Abad, Lucille V.; Aranilla, Charito T.; Relleve, Lorna S.; Dela Rosa, Alumanda M.

    2014-10-01

    The Philippines supplies almost half of the world's processed carrageenan as ingredient for different applications. In order to maintain the country's competitive advantage, R&D on radiation processed carrageenan with various potential applications had been undertaken. PVP-carrageenan hydrogels for wound dressing had been developed. A carrageenan-based radiation dose indicator can detect radiation dose of as low as 5 kGy. Irradiated carrageenan has also been tested as plant growth promoter. Irradiated carrageenans have been found have been found to contain some antioxidant properties which increase with increasing dose and concentration. Carboxymethyl carrageenans had also been developed that shows promising effect as super water absorbent for soil conditioner in plants.

  2. Recent applications of microwave irradiation to medicinal chemistry.

    PubMed

    Alcázar, Jesús; Oehlrich, Daniel

    2010-02-01

    The demands made on the pharmaceutical industry are changing at an unprecedented pace, making modern drug discovery dependent on high speed organic synthesis. Over the last few years, different technologies have been introduced in medicinal chemistry laboratories in order to improve their productivity. Microwave-assisted organic synthesis is proving to be instrumental in the rapid synthesis of compounds with new and improved biological activities. This review highlights the application of this approach as a way to explore analogue synthesis in medicinal chemistry over the last 3 years. We describe a number of examples taken from the literature that are related to various targets within different therapeutic areas. Clearly microwave irradiation is becoming a fundamental tool for optimizing key steps in the synthesis of target compounds within the field of drug discovery.

  3. Chemical Kinetics and Properties from the Radiation Chemistry Data Center (RCDC)

    DOE Data Explorer

    The Radiation Chemistry Data Center (RCDC) is a focal point for the compilation and evaluation of kinetic, spectroscopic and thermodynamic data for processes in solution involving reactive intermediates, including free radicals and excited states. These data are primarily derived from the published literature on radiation chemistry and quantitative aspects of photochemistry. The compilations are presented as individual groups of pages corresponding to each published work. Each compilation consists of an introductory article, describing the scope of the compilation, with the considerations and criteria for data evaluation discussed. Nomenclature for the compilation is also described here. For several compilations the introduction is followed by one or more pages of links organized as an index or table of contents to the individual pages of the compilation. These links allow the browsing of the data by species name. Each page tabulates the reaction of a transient species with a particular reactant. RCDC was established at the Notre Dame Radiation Laboratory in 1965, as part of the National Standard Reference Data System.

  4. Chemistry, physico-chemistry and applications linked to biological activities of β-glucans.

    PubMed

    Barsanti, Laura; Passarelli, Vincenzo; Evangelista, Valtere; Frassanito, Anna Maria; Gualtieri, Paolo

    2011-03-01

    β-Glucans is the common name given to a group of chemically heterogeneous polysaccharides. They are long- or short-chain polymers of (1-->3)-β-linked glucose moieties which may be branched, with the branching chains linked to the backbone by a (1-->6)-β linkage. β-(1-->3)-Glucans are widely distributed in bacteria, algae, fungi and plants, where they are involved in cell wall structure and other biological function. β-Glucans have been shown to provide a remarkable range of health benefits, and are especially important against the two most common conventional causes of death in industrialized countries, i.e. cardiovascular diseases (where they promote healthy cholesterol and blood glucose levels) and cancer (where they enhance immune system functions). This Highlight provides a comprehensive and up-to-date commentary on β-glucans, their chemistry, physico-chemistry, functional role in immunological responses, and possible applications as therapeutic tools. In addition, we discuss the mechanism behind their health benefits, which are not yet fully understood.

  5. Biomedical applications of radiative decay engineering

    NASA Astrophysics Data System (ADS)

    Lakowicz, Joseph R.; Gryczynski, Ignacy; Malicka, Joanna; Shen, Yibing; Gryczynski, Zygmunt

    2002-06-01

    Fluorescence spectroscopy is a widely used research tool in biochemistry and has also become the dominant method enabling the revolution in medical diagnostics, DNA sequencing and genomics. In this forward-looking article we describe a new opportunity in fluorescence, radiative decay engineering (RDE). By RDE we mean modifying the emission of fluorophores or chromophores by a nearby metallic surface, the most important effect being an increase in the radiative decay rate. We describe the usual effects expected form increase in the radiative rates with reference to the biomedical applications of immunoassay and DNA hybridization. We also present experiments which show that metallic particles can increase the quantum yield of low quantum yield fluorophores, increase fluorophore photostability and increase the distance for resonance energy transfer. And finally we show that proximity to silver particles can increase the intensity of the intrinsic fluorescence from DNA.

  6. Applications of synchrotron radiation to Chemical Engineering Science: Workshop report

    SciTech Connect

    Not Available

    1991-07-01

    This report contains extended abstracts that summarize presentations made at the Workshop on Applications of Synchrotron Radiation to Chemical Engineering Science held at Argonne National Laboratory (ANL), Argonne, IL, on April 22--23, 1991. The talks emphasized the application of techniques involving absorption fluorescence, diffraction, and reflection of synchrotron x-rays, with a focus on problems in applied chemistry and chemical engineering, as well as on the use of x-rays in topographic, tomographic, and lithographic procedures. The attendees at the workshop included experts in the field of synchrotron science, scientists and engineers from ANL, other national laboratories, industry, and universities; and graduate and undergraduate students who were enrolled in ANL educational programs at the time of the workshop. Talks in the Plenary and Overview Session described the status of and special capabilities to be offered by the Advanced Photon Source (APS), as well as strategies and opportunities for utilization of synchrotron radiation to solve science and engineering problems. Invited talks given in subsequent sessions covered the use of intense infrared, ultraviolet, and x-ray photon beams (as provided by synchrotrons) in traditional and nontraditional areas of chemical engineering research related to electrochemical and corrosion science, catalyst development and characterization, lithography and imaging techniques, and microanalysis.

  7. Tunable lasers and their application in analytical chemistry

    NASA Technical Reports Server (NTRS)

    Steinfeld, J. I.

    1975-01-01

    The impact that laser techniques might have in chemical analysis is examined. Absorption, scattering, and heterodyne detection is considered. Particular emphasis is placed on the advantages of using frequency-tunable sources, and dye solution lasers are regarded as the outstanding example of this type of laser. Types of spectroscopy that can be carried out with lasers are discussed along with the ultimate sensitivity or minimum detectable concentration of molecules that can be achieved with each method. Analytical applications include laser microprobe analysis, remote sensing and instrumental methods such as laser-Raman spectroscopy, atomic absorption/fluorescence spectrometry, fluorescence assay techniques, optoacoustic spectroscopy, and polarization measurements. The application of lasers to spectroscopic methods of analysis would seem to be a rewarding field both for research in analytical chemistry and for investments in instrument manufacturing.

  8. Applications of Optical Microcavity Resonators in Analytical Chemistry.

    PubMed

    Wade, James H; Bailey, Ryan C

    2016-06-12

    Optical resonator sensors are an emerging class of analytical technologies that use recirculating light confined within a microcavity to sensitively measure the surrounding environment. Bolstered by advances in microfabrication, these devices can be configured for a wide variety of chemical or biomolecular sensing applications. We begin with a brief description of optical resonator sensor operation, followed by discussions regarding sensor design, including different geometries, choices of material systems, methods of sensor interrogation, and new approaches to sensor operation. Throughout, key developments are highlighted, including advancements in biosensing and other applications of optical sensors. We discuss the potential of alternative sensing mechanisms and hybrid sensing devices for more sensitive and rapid analyses. We conclude with our perspective on the future of optical microcavity sensors and their promise as versatile detection elements within analytical chemistry.

  9. Recent Advances in Glycerol Polymers: Chemistry and Biomedical Applications

    PubMed Central

    Zhang, Heng

    2015-01-01

    Glycerol polymers are attracting increased attention due to the diversity of polymer compositions and architectures available. This article provides a brief chronological review on the current status of these polymers along with representative examples of their use for biomedical applications. First, we describe the underlying chemistry of glycerol, which provides access to a range of monomers for subsequent polymerizations. We then review the various synthetic methodologies to prepare glycerol-based polymers including polyethers, polycarbonates, polyesters, and so forth. Next, we describe several biomedical applications where glycerol polymers are being investigated including carriers for drug delivery, sealants or coatings for tissue repair, and agents possessing antibacterial activity. Fourth, we describe the growing market opportunity for the use of polymers in medicine. Finally we conclude and summarize the findings, as well as discuss potential opportunities for continued research efforts. PMID:25308354

  10. Recent advances in glycerol polymers: chemistry and biomedical applications.

    PubMed

    Zhang, Heng; Grinstaff, Mark W

    2014-11-01

    Glycerol polymers are attracting increased attention due to the diversity of polymer compositions and architectures available. This article provides a brief chronological review on the current status of these polymers along with representative examples of their use for biomedical applications. First, the underlying chemistry of glycerol that provides access to a range of monomers for subsequent polymerizations is described. Then, the various synthetic methodologies to prepare glycerol-based polymers including polyethers, polycarbonates, polyesters, and so forth are reviewed. Next, several biomedical applications where glycerol polymers are being investigated including carriers for drug delivery, sealants or coatings for tissue repair, and agents possessing antibacterial activity are described. Fourth, the growing market opportunity for the use of polymers in medicine is described. Finally, the findings are concluded and summarized, as well as the potential opportunities for continued research efforts are discussed.

  11. Detecting Secondary Bottlenecks in Parallel Quantum Chemistry Applications Using MPI

    NASA Astrophysics Data System (ADS)

    Mahajan, Reema; Kranzlmüller, Dieter; Volkert, Jens; Hansmann, Ulrich H. E.; Höfinger, Siegfried

    Profiling tools such as gprof and ssrun are used to analyze the run-time performance of a scientific application. The profiling is done in serial and in parallel mode using MPI as the communication interface. The application is a quantum chemistry program using Hartree Fock theory and Pulays DIIS method. An extensive set of test cases is taken into account in order to reach uniform conclusions. A known problem with decreased parallel scalability can thus be narrowed down to a single subroutine responsible for the reduction in Speed Up. The critical module is analyzed and a typical pitfall with triple matrix multiplications is identified. After overhauling the critical subroutine re-examination of the run-time behavior shows significantly improved performance and markedly improved parallel scalability. The lessons learned here might be of interest to other people working in similar fields with similar problems.

  12. The Effect of Web-Based Project Applications on Students' Attitudes towards Chemistry

    ERIC Educational Resources Information Center

    Morgil, Inci; Gungor Seyhan, Hatice; Ural Alsan, Evrim; Temel, Senar

    2008-01-01

    Students perform intensive web-based applications during their education. One of these is project-based application. In this study, the effect of web based project applications on students' attitudes towards chemistry has been investigated. 42 students attending Hacettepe University, Faculty of Education, and Department of Chemistry Education have…

  13. Intense terahertz radiation and their applications

    NASA Astrophysics Data System (ADS)

    Hafez, H. A.; Chai, X.; Ibrahim, A.; Mondal, S.; Férachou, D.; Ropagnol, X.; Ozaki, T.

    2016-09-01

    In this paper, we will review both past and recent progresses in the generation, detection and application of intense terahertz (THz) radiation. We will restrict the review to laser based intense few-cycle THz sources, and thus will not include sources such as synchrotron-based or narrowband sources. We will first review the various methods used for generating intense THz radiation, including photoconductive antennas (PCAs), optical rectification sources (especially the tilted-pulse-front lithium niobate source and the DAST source, but also those using other crystals), air plasma THz sources and relativistic laser-plasma sources. Next, we will give a brief introduction on the common methods for coherent THz detection techniques (namely the PCA technique and the electro-optic sampling), and point out the limitations of these techniques for measuring intense THz radiation. We will then review three techniques that are highly suited for detecting intense THz radiation, namely the air breakdown coherent detection technique, various single-shot THz detection techniques, and the spectral-domain interferometry technique. Finally, we will give an overview of the various applications that have been made possible with such intense THz sources, including nonlinear THz spectroscopy of condensed matter (optical-pump/THz-probe, THz-pump/THz-probe, THz-pump/optical-probe), nonlinear THz optics, resonant and non-resonant control of material (such as switching of superconductivity, magnetic and polarization switching) and controlling the nonlinear response of metamaterials. We will also provide a short perspective on the future of intense THz sources and their applications.

  14. Radiative Effect of Clouds on Tropospheric Chemistry: Sensitivity to Cloud Vertical Distributions and Optical Properties

    NASA Astrophysics Data System (ADS)

    Liu, H.; Crawford, J. H.; Pierce, R. B.; Considine, D. B.; Logan, J. A.; Duncan, B. N.; Norris, P.; Platnick, S. E.; Chen, G.; Yantosca, R. M.; Evans, M. J.

    2005-12-01

    Representation of clouds in global models poses a significant challenge since most cloud processes occur on sub-grid scales and must be parameterized. Uncertainties in cloud distributions and optical properties are therefore a limiting factor in model assessments of the radiative effect of clouds on global tropospheric chemistry. We present an analysis of the sensitivity of the radiative effect of clouds to cloud vertical distributions and optical properties with the use of the GEOS-CHEM global 3-D chemistry transport model coupled with the Fast-J radiative transfer algorithm. GEOS-CHEM was driven with a series of meteorological archives (GEOS1-STRAT, GEOS-3, and GEOS-4) generated by the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA global Modeling and Assimilation Office (GMAO), which have significantly different cloud optical depths and vertical distributions. The column cloud optical depths in GEOS-3 generally agree with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP) within ±10%, while those in GEOS1-STRAT and GEOS-4 are too low by factors of about 5 and 2, respectively. With respect to vertical distribution, clouds in GEOS-4 are optically much thinner in the tropical upper troposphere compared to those in GEOS1-STRAT and GEOS-3. Assuming linear scaling of cloud optical depth with cloud fraction in a grid-box, our model calculations indicate that the changes in global mean hydroxyl radical (OH) due to the radiative effect of clouds in June are about -1% (GEOS1-STRAT), 1% (GEOS-3), and 14% (GEOS-4), respectively. The effects on global mean OH are similar for GEOS1-STRAT and GEOS-3 due to similar vertical distributions of clouds, even though the column cloud optical depths in the two archives differ by a factor of about 5. Clouds in GEOS-4 have a much larger impact on global mean OH because more solar radiation is

  15. A Radiation Chemistry Code Based on the Greens Functions of the Diffusion Equation

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Wu, Honglu

    2014-01-01

    Ionizing radiation produces several radiolytic species such as.OH, e-aq, and H. when interacting with biological matter. Following their creation, radiolytic species diffuse and chemically react with biological molecules such as DNA. Despite years of research, many questions on the DNA damage by ionizing radiation remains, notably on the indirect effect, i.e. the damage resulting from the reactions of the radiolytic species with DNA. To simulate DNA damage by ionizing radiation, we are developing a step-by-step radiation chemistry code that is based on the Green's functions of the diffusion equation (GFDE), which is able to follow the trajectories of all particles and their reactions with time. In the recent years, simulations based on the GFDE have been used extensively in biochemistry, notably to simulate biochemical networks in time and space and are often used as the "gold standard" to validate diffusion-reaction theories. The exact GFDE for partially diffusion-controlled reactions is difficult to use because of its complex form. Therefore, the radial Green's function, which is much simpler, is often used. Hence, much effort has been devoted to the sampling of the radial Green's functions, for which we have developed a sampling algorithm This algorithm only yields the inter-particle distance vector length after a time step; the sampling of the deviation angle of the inter-particle vector is not taken into consideration. In this work, we show that the radial distribution is predicted by the exact radial Green's function. We also use a technique developed by Clifford et al. to generate the inter-particle vector deviation angles, knowing the inter-particle vector length before and after a time step. The results are compared with those predicted by the exact GFDE and by the analytical angular functions for free diffusion. This first step in the creation of the radiation chemistry code should help the understanding of the contribution of the indirect effect in the

  16. Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC

    PubMed Central

    Brühl, C; Lelieveld, J; Tost, H; Höpfner, M; Glatthor, N

    2015-01-01

    Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO2, the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m2. For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m2, leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions. PMID:25932352

  17. Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC

    NASA Astrophysics Data System (ADS)

    Brühl, C.; Lelieveld, J.; Tost, H.; Höpfner, M.; Glatthor, N.

    2015-03-01

    Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO2, the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m2. For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m2, leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions.

  18. Radiation design criteria handbook. [design criteria for electronic parts applications

    NASA Technical Reports Server (NTRS)

    Stanley, A. G.; Martin, K. E.; Douglas, S.

    1976-01-01

    Radiation design criteria for electronic parts applications in space environments are provided. The data were compiled from the Mariner/Jupiter Saturn 1977 electronic parts radiation test program. Radiation sensitive device types were exposed to radiation environments compatible with the MJS'77 requirements under suitable bias conditions. A total of 189 integrated circuits, transistors, and other semiconductor device types were tested.

  19. Stratospheric Heterogeneous Chemistry and Microphysics: Model Development, Validation and Applications

    NASA Technical Reports Server (NTRS)

    Turco, Richard P.

    1996-01-01

    being systematically evaluated to identify the principal relationships between ozone loss and aerosol state. Under this project, we formulated a detailed quantitative model that predicts the multicomponent composition of sulfate aerosols under stratospheric conditions, including sulfuric, nitric, hydrochloric, hydrofluoric and hydrobromic acids. This work defined for the first time the behavior of liquid ternary-system type-1b PSCS. The model also allows the compositions and reactivities of sulfate aerosols to be calculated over the entire range of environmental conditions encountered in the stratosphere (and has been incorporated into a trajectory/microphysics model-see above). Important conclusions that derived from this work over the last few years include the following: the HNO3 content of liquid-state aerosols dominate PSCs below about 195 K; the freezing of nitric acid ice from sulfate aerosol solutions is likely to occur within a few degrees K of the water vapor frost point; the uptake and reactions of HCl in liquid aerosols is a critical component of PSC heterogeneous chemistry. In a related application of this work, the inefficiency of chlorine injection into the stratosphere during major volcanic eruptions was explained on the basis of nucleation of sulfuric acid aerosols in rising volcanic plumes leading to the formation of supercooled water droplets on these aerosols, which efficiently scavenges HCl via precipitation.

  20. Applications of mineral surface chemistry to environmental problems

    NASA Astrophysics Data System (ADS)

    White, Art F.

    1995-07-01

    Environmental surface chemistry involves processes that occur at the interface between the regolith, hydrosphere and atmosphere. The more limited scope of the present review addresses natural and anthropogenically-induced inorganic geochemical reactions between solutes in surface and ground waters and soil and aquifer substrates. Important surficial reactions include sorption, ion exchange, dissolution, precipitation and heterogeneous oxidation/reduction processes occurring at the solid/aqueous interface. Recent research advances in this field have addressed, both directly and indirectly, societal issues related to water quality, pollution, biogeochemical cycling, nutrient budgets and chemical weathering related to long term global climate change. This review will include recent advances in the fundamental and theoretical understanding of these surficial processes, breakthroughs in experimental and instrumental surface characterization, and development of methodologies for field applications.

  1. Reevaluation of Neptunium-Nitric Acid Radiation Chemistry by Multiscale Modeling.

    PubMed

    Horne, G P; Grimes, T S; Mincher, B J; Mezyk, S P

    2016-12-15

    Multiscale modeling has been used to quantitatively reevaluate the radiation chemistry of neptunium in a range of aerated nitric acid solutions (0.1-6.0 mol dm(-3)). Exact calculation of initial radiolytic yields accounting for changes in radiation track chemistry was found to be crucial for reproducing experimental data. The γ irradiation induces changes in the Np(VI)/Np(V) oxidation-state distribution, predominantly driven by reactions involving HNO2, H2O2, NO2(•), and NO3(•) from the radiolysis of aqueous nitric acid. Oxidation of Np(V) by NO3(•) (k = 8.1 × 10(8) dm(3) mol(-1) s(-1)) provides the initial increase in Np(VI) concentration, while also delaying net reduction of Np(VI) by consuming HNO2. Reduction of Np(VI) is dominated by thermal reactions with HNO2 (k = 0.7-73 dm(3) mol(-1) s(-1)) and H2O2 (k = 1.9 dm(3) mol(-1) s(-1)). A steady state is eventually established once the concentration of Np(V) is sufficiently high to be oxidized by NO2(•) (k = 2.4 × 10(2)-3.1 × 10(4) dm(3) mol(-1) s(-1)). An additional thermal oxidation reaction between Np(V) and HNO3 (k = 2.0 × 10(3) dm(3) mol(-1) s(-1)) is required for nitric acid concentrations >4.0 mol dm(-3). For 0.1 mol dm(-3) HNO3, the rate of Np(VI) reduction is in excess of that which can be accounted for by radiolytic product mass balance, suggesting the existence of a catalytic-acid-dependent reduction process.

  2. Can a coupled meteorology–chemistry model reproduce the historical trend in aerosol direct radiative effects over the Northern Hemisphere?

    EPA Science Inventory

    The ability of a coupled meteorology–chemistry model, i.e., Weather Research and Forecast and Community Multiscale Air Quality (WRF-CMAQ), to reproduce the historical trend in aerosol optical depth (AOD) and clear-sky shortwave radiation (SWR) over the Northern Hemisphere h...

  3. Polymer recycling: potential application of radiation technology

    NASA Astrophysics Data System (ADS)

    Burillo, Guillermina; Clough, Roger L.; Czvikovszky, Tibor; Guven, Olgun; Le Moel, Alain; Liu, Weiwei; Singh, Ajit; Yang, Jingtian; Zaharescu, Traian

    2002-04-01

    Management of solid waste is an important problem, which is becoming progressively worse as a byproduct of continuing economic growth and development. Polymeric materials (plastics and rubbers) comprise a steadily increasing proportion of the municipal and industrial waste going into landfill. Development of technologies for reducing polymeric waste, which are acceptable from the environmental standpoint, and which are cost-effective, has proven to be a difficult challenge due to complexities inherent in the reuse of polymers. Establishing optimal processes for the reuse/recycling of polymeric materials thus remains a worldwide challenge as we enter the new century. Due to the ability of ionizing radiation to alter the structure and properties of bulk polymeric materials, and the fact that it is applicable to essentially all polymer types, irradiation holds promise for impacting the polymer waste problem. The three main possibilities for use of radiation in this application are: (1) enhancing the mechanical properties and performance of recovered materials or material blends, principally through crosslinking, or through surface modification of different phases being combined; (2) treatment causing or enhancing the decomposition of polymers, particularly through chain scission, leading to recovery of either low molecular weight mixtures, or powders, for use as chemical feedstocks or additives; (3) production of advanced polymeric materials designed for environmental compatibility. This paper provides an overview of the polymer recycling problem, describes the major technological obstacles to the implementation of recycling technologies, and outlines some of the approaches being taken. A review of radiation-based recycling research is then provided, followed by a discussion of future directions where irradiation may be relevant to the problems currently inhibiting the widespread recycling of polymeric materials.

  4. Comparative Experimental Investigation of Titan's Atmospheric Chemistry Driven by Solar EUV Radiation and Energetic Electron Precipitation

    NASA Astrophysics Data System (ADS)

    Imanaka, Hiroshi; Lavvas, P.; Yelle, R. V.; Smith, M. A.

    2010-10-01

    The observations by the Cassini Ion Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) clearly demonstrate the importance of complex organic chemistry in the upper atmosphere of Titan; a complex coupling of neutral and ion chemistry for organic aerosol generation induced by EUV photons and Saturn's magnetospheric charged particles. To understand the dominant energy source for aerosol formation and its formation chemistry, we comparatively investigate the chemical mechanism in N2/CH4 gas mixtures resulting from EUV-VUV synchrotron radiation (50-150 nm) and tunable mono-energetic electron beam irradiation (5 eV - 2000 eV). These excitation energy sources cover the dominant energy source available in Titan's upper atmosphere. Our previous study of the EUV-VUV photolysis of N2/CH4 gas mixtures revealed the unique role of nitrogen photoionization in the catalytic formation of complex hydrocarbons and in the major nitrogen fixation process in Titan's upper atmosphere (Imanaka and Smith, 2007, 2009, 2010). However, relative roles of ion-molecule reactions and radical/neutral reactions in such complex chemistry remain to be determined. We characterized the electron energy distribution by conducting the Langmuir probe measurements. Degradation of the primary photoelectron from N2 photoionization at 20.6 eV photons is clearly observed, and the electron density rapidly decreases down to 109-10 cm-3, which suggests the complex coupling of ion-molecular reactions and dissociative ion-electron recombination reactions for the observed development of complex organic molecules. The electron beam irradiation experiments at energy larger than 200 eV shows distinct gaseous product distribution with nitrogenated gaseous species from those with EUV irradiation products. The generation of secondary electrons and multiple inelastic collisions of fast electrons might increases the nitrogen fixation efficiency. The much less stringent spin selection rules could

  5. Nuclear analytical chemistry

    SciTech Connect

    Brune, D.; Forkman, B.; Persson, B.

    1984-01-01

    This book covers the general theories and techniques of nuclear chemical analysis, directed at applications in analytical chemistry, nuclear medicine, radiophysics, agriculture, environmental sciences, geological exploration, industrial process control, etc. The main principles of nuclear physics and nuclear detection on which the analysis is based are briefly outlined. An attempt is made to emphasise the fundamentals of activation analysis, detection and activation methods, as well as their applications. The book provides guidance in analytical chemistry, agriculture, environmental and biomedical sciences, etc. The contents include: the nuclear periodic system; nuclear decay; nuclear reactions; nuclear radiation sources; interaction of radiation with matter; principles of radiation detectors; nuclear electronics; statistical methods and spectral analysis; methods of radiation detection; neutron activation analysis; charged particle activation analysis; photon activation analysis; sample preparation and chemical separation; nuclear chemical analysis in biological and medical research; the use of nuclear chemical analysis in the field of criminology; nuclear chemical analysis in environmental sciences, geology and mineral exploration; and radiation protection.

  6. Carbohydrate-based bioactive compounds for medicinal chemistry applications.

    PubMed

    Cipolla, L; Peri, F

    2011-01-01

    In this article we review our work over the years on carbohydrates and carbohydrate mimetics and their applications in medicinal chemistry. In the first part of the review innovative synthetic methods, such as the chemoselective glycosylation method originally developed by our group and its applications to the synthesis of neoglycoconjugates (neoglycopeptides, oligosaccharide mimetics, neoglycolipids, etc…) will be presented. The high density of functional groups (hydroxyls) on the monosaccharides and the structural role of sugars forming the core of complex glycans in scaffolding and orienting the external sugar units for the interaction with receptors, inspired us and others to use sugars as scaffolds for the construction of pharmacologically active compounds. In the second part of this review, we will present some examples of bioactive and pharmacologically active compounds obtained by decorating monosaccharide scaffolds with pharmacophore groups. Sugar-derived protein ligands were also used as chemical probes to study the interaction of their target with other proteins in the cell. In this context, sugar mimetics and sugar-derived compounds have been employed as tools for exploring biology according to the "chemical genetic" approach.

  7. Finite-rate chemistry effects upon convective and radiative heating of an atmospheric entry vehicle. [reentry aerothermochemistry

    NASA Technical Reports Server (NTRS)

    Guillermo, P.

    1975-01-01

    A mathematical model of the aerothermochemical environment along the stagnation line of a planetary return spacecraft using an ablative thermal protection system was developed and solved for conditions typical of atmospheric entry from planetary missions. The model, implemented as a FORTRAN 4 computer program, was designed to predict viscous, reactive and radiative coupled shock layer structure and the resulting body heating rates. The analysis includes flow field coupling with the ablator surface, binary diffusion, coupled line and continuum radiative and equilibrium or finite rate chemistry effects. The gas model used includes thermodynamic, transport, kinetic and radiative properties of air and ablation product species, including 19 chemical species and 16 chemical reactions. Specifically, the impact of nonequilibrium chemistry effects upon stagnation line shock layer structure and body heating rates was investigated.

  8. Infrared synchrotron radiation instrumentation and applications

    NASA Astrophysics Data System (ADS)

    Williams, Gwyn P.

    1992-01-01

    Infrared synchrotron radiation (IRSR) in the wavelength range from 1 μm to ˜1 cm has now been used quite extensively both in Japan at UVSOR, Okasaki and in the United States at the NSLS, Brookhaven, following an earlier program at the first infrared beamline at Daresbury in England. Elsewhere around the world, several new beamlines are under construction or planned-including a new facility at Daresbury (UK), and those at Lund (Sweden), SuperACO (France), ADONE (Italy), and the ALS (USA). The use of IRSR poses many new challenges, none the least of which is the fact that the radiation covers four decades of energy and is also very divergent and subject to diffraction. However the advantages are particularly significant due to the 1000-fold increase in brightness available over conventional sources in a region where detectors become a limiting factor. In addition, IRSR is also highly spatially coherent allowing the possibility of a new class of interferometers based on wave front division. We will discuss this and other instrumentation issues as they critically relate to experiments. The applications discussed will be in the areas of surface vibrational spectroscopy, both in ultrahigh vacuum and in electrochemical cells, and in areas which use the pulsed nature of the source both for fast response studies and for pump-probe studies.

  9. Synchrotron radiation applications in medical research

    SciTech Connect

    Thomlinson, W.

    1995-12-31

    The medical projects employing synchrotron radiation as discussed in this paper are, for the most part, still in their infancies and no one can predict the direction in which they will develop. Both the basic research and applied medical programs are sure to be advanced at the new facilities coming on line, especially the ESRF and Spring- 8. However, success is not guaranteed. There is a lot of competition from advances in conventional imaging with the development of digital angiography, computed tomography, functional magnetic resonance imaging and ultrasound. The synchrotron programs will have to provide significant advantages over these modalities in order to be accepted by the medical profession. Advances in image processing and potentially the development of compact sources will be required in order to move the synchrotron developed imaging technologies into the clinical world. In any event, it can be expected that the images produced by the synchrotron technologies will establish ``gold standards`` to be targeted by conventional modalities. A lot more work needs to be done in order to bring synchrotron radiation therapy and surgery to the level of human studies and, subsequently, to clinical applications.

  10. The effects of UV radiation, litter chemistry, and drought on desert litter decomposition

    NASA Astrophysics Data System (ADS)

    Lee, H.; Nieto, B.; Hewins, D. B.; Barnes, P. W.; McDowell, N. G.; Pockman, W.; Rahn, T.; Throop, H. L.

    2011-12-01

    Recent studies suggest that photodegradation by solar UV radiation can be a major driver of litter decomposition in dryland ecosystems. The importance of photodegradation in litter decomposition appears to decline with precipitation, suggesting that the relative importance of photodegradation may increase given current projections of future increases in drought severity in the southwestern USA. Several previous studies indicate that UV-B radiation (280-320 nm) is the most effective waveband in breaking chemical bonds forming organic material, but whether UV-B exposure may facilitate subsequent decomposition by microbes (i.e., photo-priming) has received little attention. In this study, we tested the effects of pre-exposure UV radiation (photo-priming), litter chemistry (lignin and cellulose content and nitrogen content), and drought on the rate of litter decomposition in a semi-arid ecosystem. To understand the effects of UV radiation on litter decomposition, we pre-exposed litter to three radiation treatments: control (no radiation), UV-A+visible, UV-A+UV-B+visible. Litter was exposed to the equivalent of three months' solar radiation of southern New Mexico prior to microbial decomposition. There were three litter types: basswood sheets (high lignin content), pure cellulose filter paper, and mesquite (Prosopis glandulosa) leaflets. Following radiation treatment, litter was placed in mesh litterbags that were buried within a large-scale precipitation manipulation experiment at the Sevilleta Long-Term Ecological Research site: control (ambient precipitation), elevated precipitation (x2 ambient precipitation), and drought (x0.5 ambient precipitation). We collected a subset of bags at 0, 1, 3, and 6 months and measured mass remaining and carbon (C) and nitrogen (N) content. After 6 months, mass remaining of filter paper and basswood sheets did not differ from the initial mass, but mesquite mass remaining declined over 30%. The pre-exposure UV effects had minimal

  11. Nuclear Cross Sections for Space Radiation Applications

    NASA Technical Reports Server (NTRS)

    Werneth, C. M.; Maung, K. M.; Ford, W. P.; Norbury, J. W.; Vera, M. D.

    2015-01-01

    The eikonal, partial wave (PW) Lippmann-Schwinger, and three-dimensional Lippmann-Schwinger (LS3D) methods are compared for nuclear reactions that are relevant for space radiation applications. Numerical convergence of the eikonal method is readily achieved when exact formulas of the optical potential are used for light nuclei (A = 16) and the momentum-space optical potential is used for heavier nuclei. The PW solution method is known to be numerically unstable for systems that require a large number of partial waves, and, as a result, the LS3D method is employed. The effect of relativistic kinematics is studied with the PW and LS3D methods and is compared to eikonal results. It is recommended that the LS3D method be used for high energy nucleon-nucleus reactions and nucleus-nucleus reactions at all energies because of its rapid numerical convergence and stability for both non-relativistic and relativistic kinematics.

  12. Five Applications of Computers in the Chemistry Curriculum.

    ERIC Educational Resources Information Center

    Johnson, K. Jeffrey

    1981-01-01

    Describes the use of computer courseware in an undergraduate chemistry curriculum for (1) a tutorial program, (2) a computer assisted test construction (CATC) system, (3) a set of simulation and data reduction programs, (4) a "Numerical Methods in Chemistry" course, and (5) a library of computer managed instruction (CMI) programs. (JL)

  13. Anisotropic conducting films for electromagnetic radiation applications

    DOEpatents

    Cavallo, Francesca; Lagally, Max G.; Rojas-Delgado, Richard

    2015-06-16

    Electronic devices for the generation of electromagnetic radiation are provided. Also provided are methods for using the devices to generate electromagnetic radiation. The radiation sources include an anisotropic electrically conducting thin film that is characterized by a periodically varying charge carrier mobility in the plane of the film. The periodic variation in carrier mobility gives rise to a spatially varying electric field, which produces electromagnetic radiation as charged particles pass through the film.

  14. Preparedness for Tertiary Chemistry: Multiple Applications of the Chemistry Competence Test for Diagnostic and Prediction Purposes

    ERIC Educational Resources Information Center

    Potgieter, Marietjie; Davidowitz, Bette

    2011-01-01

    The development of the Chemistry Competence Test was prompted by the extensive curriculum changes in the South African school system after democracy was established in 1994. As chemists, we were concerned that there might be a lack of articulation between secondary and tertiary levels, since we anticipated that curriculum changes would have an…

  15. Growing applications of "click chemistry" for bioconjugation in contemporary biomedical research.

    PubMed

    Nwe, Kido; Brechbiel, Martin W

    2009-06-01

    This update summarizes the growing application of "click" chemistry in diverse areas such as bioconjugation, drug discovery, materials science, and radiochemistry. This update also discusses click chemistry reactions that proceed rapidly with high selectivity, specificity, and yield. Two important characteristics make click chemistry so attractive for assembling compounds, reagents, and biomolecules for preclinical and clinical applications. First, click reactions are bio-orthogonal; neither the reactants nor their product's functional groups interact with functionalized biomolecules. Second, the reactions proceed with ease under mild nontoxic conditions, such as at room temperature and, usually, in water. The copper-catalyzed Huisgen cycloaddition, azide-alkyne [3 + 2] dipolar cycloaddition, Staudinger ligation, and azide-phosphine ligation each possess these unique qualities. These reactions can be used to modify one cellular component while leaving others unharmed or untouched. Click chemistry has found increasing applications in all aspects of drug discovery in medicinal chemistry, such as for generating lead compounds through combinatorial methods. Bioconjugation via click chemistry is rigorously employed in proteomics and nucleic research. In radiochemistry, selective radiolabeling of biomolecules in cells and living organisms for imaging and therapy has been realized by this technology. Bifunctional chelating agents for several radionuclides useful for positron emission tomography and single-photon emission computed tomography imaging have also been prepared by using click chemistry. This review concludes that click chemistry is not the perfect conjugation and assembly technology for all applications, but provides a powerful, attractive alternative to conventional chemistry. This chemistry has proven itself to be superior in satisfying many criteria (e.g., biocompatibility, selectivity, yield, stereospecificity, and so forth); thus, one can expect it will

  16. EFFECT OF BIOSOLIDS APPLICATION ON SOIL METAL CHEMISTRY AND PHYTOAVAILABILITY

    EPA Science Inventory

    Addition of biosolids to soils increases the environmental loading of toxic metals (Cd, Zn, Cu, Ni, Pb, etc.) and alters the chemistry and phytoavailability of these metals. This alteration in phytoavailability associated with biosolids amended soil was recognized and utilized ...

  17. RITRACKS: A Software for Simulation of Stochastic Radiation Track Structure, Micro and Nanodosimetry, Radiation Chemistry and DNA Damage for Heavy Ions

    NASA Technical Reports Server (NTRS)

    Plante, I; Wu, H

    2014-01-01

    The code RITRACKS (Relativistic Ion Tracks) has been developed over the last few years at the NASA Johnson Space Center to simulate the effects of ionizing radiations at the microscopic scale, to understand the effects of space radiation at the biological level. The fundamental part of this code is the stochastic simulation of radiation track structure of heavy ions, an important component of space radiations. The code can calculate many relevant quantities such as the radial dose, voxel dose, and may also be used to calculate the dose in spherical and cylindrical targets of various sizes. Recently, we have incorporated DNA structure and damage simulations at the molecular scale in RITRACKS. The direct effect of radiations is simulated by introducing a slight modification of the existing particle transport algorithms, using the Binary-Encounter-Bethe model of ionization cross sections for each molecular orbitals of DNA. The simulation of radiation chemistry is done by a step-by-step diffusion-reaction program based on the Green's functions of the diffusion equation]. This approach is also used to simulate the indirect effect of ionizing radiation on DNA. The software can be installed independently on PC and tablets using the Windows operating system and does not require any coding from the user. It includes a Graphic User Interface (GUI) and a 3D OpenGL visualization interface. The calculations are executed simultaneously (in parallel) on multiple CPUs. The main features of the software will be presented.

  18. Aerosols, Chemistry, and Radiative Forcing: A 3-D Model Analysis of Satellite and ACE-Asia data (ACMAP)

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Ginoux, Paul; Torres, Omar; Zhao, Xue-Peng

    2005-01-01

    We propose a research project to incorporate a global 3-D model and satellite data into the multi-national Aerosol Characterization Experiment-Asia (ACE-Asia) mission. Our objectives are (1) to understand the physical, chemical, and optical properties of aerosols and the processes that control those properties over the Asian-Pacific region, (2) to investigate the interaction between aerosols and tropospheric chemistry, and (3) to determine the aerosol radiative forcing over the Asia-Pacific region. We will use the Georgia TecWGoddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model to link satellite observations and the ACE-Asia measurements. First, we will use the GOCART model to simulate aerosols and related species, and evaluate the model with satellite and in-situ observations. Second, the model generated aerosol vertical profiles and compositions will be used to validate the satellite products; and the satellite data will be used for during- and post- mission analysis. Third, we will use the model to analyze and interpret both satellite and ACE- Asia field campaign data and investigate the aerosol-chemistry interactions. Finally, we will calculate aerosol radiative forcing over the Asian-Pacific region, and assess the influence of Asian pollution in the global atmosphere. We propose a research project to incorporate a global 3-D model and satellite data into

  19. Applications of carbon nanotubes in bioanalytical chemistry research

    NASA Astrophysics Data System (ADS)

    Koehne, Jessica E.

    This dissertation focuses on the interface and study of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) with biology. The goal was to take advantage of the nanostructure of CNTs and CNFs for unconventional biomolecular studies requiring ultrahigh sensitivity, resolution, high-degree of miniaturization, and selective biofunctionalization. In this dissertation, CNFs were utilized as ultramicroelectrodes for novel biomolecule sensing and cell penetrating platforms, CNTs were utilized as high resolution atomic force microscopy (AFM) imaging probes for cell morphology investigations and CNTs were utilized to generate a platform by which to evaluate nanomaterial phytotoxicity. CNF arrays were utilized for ultrahigh sensitivity sensing and cell penetration platforms. Arrays of CNFs harness the advantages of an individual CNF as well the collective property of assemblies, which made them promising materials in biosensing and tissue engineering or implantation. Two CNF platforms were demonstrated. One platform exploited the CNF's nanoscale and strong conductance as ultramicroelectrodes for biomolecule sensing applications. The other platform made use of CNF's high aspect ratio structure to be an array of needle-like electrodes that support PC-12 cell growth and penetrated through the cell membrane. The goal was to take advantage of the nanostructure of CNFs for biomolecule detection and cell interfacing studies. CNT AFM probes were utilized for morphological characterization of fixed rat basophilic lymphocyte (RBL) cells. CNT AFM probes offer advantages in the visualization of cellular membrane morphology. Due to the inherent high aspect ratio geometry, CNT AFM probes were able to resolve unique membrane features, such as lamelopodia, filopodia and microvilli, of a spreading RBL cell where standard silicon probes could not. The structures resolved by the CNT probes are crucial to characterize cellular events such as spreading, locomotion, activation and differentiation

  20. Hyperbranched polymer films and dendrimers: Their chemistry and applications

    NASA Astrophysics Data System (ADS)

    Zhao, Mingqi

    The research in this dissertation examines the chemistry and applications of dendritic polymers; specifically, hyperbranched polymer thin films and dendrimers. We examined hyperbranched, fluorinated and unfluorinated poly(acrylic acid) (PAA) films on gold substrates, poly(amidoamine) (PAMAM) dendrimer monolayers and dendrimer-alkanethiol mixed monolayers on gold substrates, PAMAM dendrimer/poly(anhydride) and poly(iminopropane-1,3-diyl) (Cascade) dendrimer/poly(anhydride) multilayer films on silicon, gold, and aluminum substrates, PAMAM dendrimer/metal-ion composites, and PAMAM dendrimer-encapsulated metal nanoclusters in solution and on electrode surfaces. Hyperbranched PAA films have pH-dependent blocking abilities: at low pH PAA films effectively passivate Au electrodes while at high pH they are open and permeable. Fluorinated PAA films are far less permeable at any pH. Dendrimers ranging from generation 4 to 8 (G4--G8) can form highly stable and nearly close-packed monolayers and mixed monolayers with hexadecanethiol (C16SH) on surfaces. Moreover, dendrimers embedded within C16SH can act as gates of molecular dimension that control intradendrimer mass transfer of ions. Dendrimer/poly(anhydride) multilayers on surfaces were synthesized and their permeability was investigated. These composite membranes exhibit fully reversible, pH-switchable permselectivity for both cationic and anionic probe molecules because of their pH-dependent electrostatic properties. After heating, such films become highly blocking over the pH range studied due to thermally induced interdendrimer imidization, and other reactions. Finally, we show that PAMAM dendrimers can act first as templates for the preparation of transition-metal nanoclusters, and subsequently as stabilizers. Dendrimers quantitatively complex many transition-metal ions, including Cu 2+, Pt2+, Pd2+, Ru3+, and Ni2+, within their interiors. Chemical reduction of such nanocomposites results in formation of dendrimer

  1. Heat pipe technology development for high temperature space radiator applications

    SciTech Connect

    Merrigan, M.A.; Keddy, E.S.; Sena, J.T.; Elder, M.G.

    1984-01-01

    Technology requirements for heat pipe radiators, potentially among the lightest weight systems for space power applications, include flexible elements, and improved specific radiator performance(kg/kW). For these applications a flexible heat pipe capable of continuous operation through an angle of 180/sup 0/ has been demonstrated. The effect of bend angle on the heat pipe temperature distribution is reviewed. An analysis of lightweight membrane heat pipe radiators that use surface tension forces for fluid containment has been conducted. The design analysis of these lightweight heat pipes is described and a potential application in heat rejection systems for space nuclear power plants outlined.

  2. Heat pipe technology development for high temperature space radiator applications

    SciTech Connect

    Merrigan, M.A.; Elder, M.G.; Keddy, E.S.; Sena, J.T.

    1984-08-01

    Technology requirements for heat pipe radiators, potentially among the lightest weight systems for space power applications, include flexible elements, and improved specific radiator performance (kg/kW). For these applications a flexible heat pipe capable of continuous operation through an angle of 180/sup 0/ has been demonstrated. The effect of bend angle on the heat pipe temperature distribution is reviewed. An analysis of light weight membrane heat pipe radiators that use surface tension forces for fluid containment has been conducted. The design analysis of these lightweight heat pipes is described and a potential application in heat rejection systems for space nuclear power plants outlined.

  3. Diversity of biomedical applications of acoustic radiation force.

    PubMed

    Sarvazyan, Armen

    2010-02-01

    This manuscript is a summary of the paper presented at the ICU'2009 on biomedical applications of acoustic radiation force with emphasis on emerging applications in microfluidics, biotechnology, biosensors and assessment of the skeletal system. In this brief overview of current and projected applications of radiation force, no detailed description of the experiments illustrating particular applications are given as this would result in a far different and longer paper. Various mechanisms of acoustic radiation force generations and their biomedical applications are considered. These mechanisms include: (a) change in the density of energy of the propagating wave due to absorption and scattering; (b) spatial variations of energy density in standing acoustic waves; (c) reflection from inclusions, walls or other interfaces; and (d) spatial variations in propagation velocity. The widest area of biomedical applications of radiation force is related to medical diagnostics, to assessing viscoelastic properties of biological tissues and fluids, and specifically to elasticity imaging. Another actively explored area is related to manipulation of biological cells and particles in standing ultrasonic wave fields. There are several poorly explored areas of potential biomedical applications of ultrasound radiation force. A promising area of biomedical application of ultrasound radiation force is stirring and mixing of microvolumes of liquids in microfluidics and in various biotechnological application where diffusion rate is the main factor limiting the efficiency of the process of interest. A new technique, called "swept frequency method", based on the use of radiation force in the standing acoustic wave for microstirring of liquids is described. The potential applications of the ultrasound radiation force for assessment of skeletal system, where conventional bone ultrasonometry are inapplicable are considered.

  4. [Applications of electromagnetic radiation in medicine].

    PubMed

    Miłowska, Katarzyna; Grabowska, Katarzyna; Gabryelak, Teresa

    2014-05-08

    Recent decades have been devoted to the intense search for the response to questions related to the impact of radiation on the human body. Due to the growing fashion for a healthy lifestyle, increasing numbers of works about the alleged dangers of electromagnetic waves and diseases that they cause appeared. However, the discoveries of 20th century, and knowledge of the properties of electromagnetic radiation have allowed to broaden the horizons of the use of artificial sources of radiation in many fields of science and especially in medicine. The aim of this paper is to show that although excessive radiation or high doses are dangerous to the human body, its careful and controlled use, does not pose a threat, and it is often necessary in therapy. The possibility of using ionizing radiation in radiotherapy, isotope diagnostics or medical imaging, and non-ionizing radiation in the treatment for dermatological disorders and cancers will be presented. The unique properties of synchrotron radiation result in using it on a large scale in the diagnosis of pathological states by imaging methods.

  5. Patterns in Organometallic Chemistry with Application in Organic Synthesis.

    ERIC Educational Resources Information Center

    Schwartz, Jeffrey; Labinger, Jay A.

    1980-01-01

    Of interest in this discussion of organometallic complexes are stoichiometric or catalytic reagents for organic synthesis in the complex transformations observed during synthesis for transition metal organometallic complexes. Detailed are general reaction types from which the chemistry or many transition metal organometallic complexes can be…

  6. Effects of urine application on chemistry of feedlot pen surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beef cattle feedlots can emit significant quantities of ammonia that may adversely affect air quality and decrease the fertilizer value of manure. The major source of ammonia loss may be urinary urea. We conducted three studies to evaluate the effects of urine on the chemistry of feedlot pen surface...

  7. The Application of Chemistry to Conserve Cultural Heritage

    ERIC Educational Resources Information Center

    MacLeod, Ian D.

    2015-01-01

    During the past 50 years the amount of chemistry applied to the preservation of all sorts of materials, from wood, to ceramics, glass and metallic objects has increased dramatically as materials conservation laboratories became established around the world. In Australia, the finding of a series of historic shipwrecks of ships from the Dutch…

  8. Prediction of Log "P": ALOGPS Application in Medicinal Chemistry Education

    ERIC Educational Resources Information Center

    Kujawski, Jacek; Bernard, Marek K.; Janusz, Anna; Kuzma, Weronika

    2012-01-01

    Molecular hydrophobicity (lipophilicity), usually quantified as log "P" where "P" is the partition coefficient, is an important molecular characteristic in medicinal chemistry and drug design. The log "P" coefficient is one of the principal parameters for the estimation of lipophilicity of chemical compounds and pharmacokinetic properties. The…

  9. he Impact of Primary Marine Aerosol on Atmospheric Chemistry, Radiation and Climate: A CCSM Model Development Study

    SciTech Connect

    Keene, William C.; Long, Michael S.

    2013-05-20

    This project examined the potential large-scale influence of marine aerosol cycling on atmospheric chemistry, physics and radiative transfer. Measurements indicate that the size-dependent generation of marine aerosols by wind waves at the ocean surface and the subsequent production and cycling of halogen-radicals are important but poorly constrained processes that influence climate regionally and globally. A reliable capacity to examine the role of marine aerosol in the global-scale atmospheric system requires that the important size-resolved chemical processes be treated explicitly. But the treatment of multiphase chemistry across the breadth of chemical scenarios encountered throughout the atmosphere is sensitive to the initial conditions and the precision of the solution method. This study examined this sensitivity, constrained it using high-resolution laboratory and field measurements, and deployed it in a coupled chemical-microphysical 3-D atmosphere model. First, laboratory measurements of fresh, unreacted marine aerosol were used to formulate a sea-state based marine aerosol source parameterization that captured the initial organic, inorganic, and physical conditions of the aerosol population. Second, a multiphase chemical mechanism, solved using the Max Planck Institute for Chemistry's MECCA (Module Efficiently Calculating the Chemistry of the Atmosphere) system, was benchmarked across a broad set of observed chemical and physical conditions in the marine atmosphere. Using these results, the mechanism was systematically reduced to maximize computational speed. Finally, the mechanism was coupled to the 3-mode modal aerosol version of the NCAR Community Atmosphere Model (CAM v3.6.33). Decadal-scale simulations with CAM v.3.6.33, were run both with and without reactive-halogen chemistry and with and without explicit treatment of particulate organic carbon in the marine aerosol source function. Simulated results were interpreted (1) to evaluate influences of

  10. Defining the radiation chemistry during liquid cell electron microscopy to enable visualization of nanomaterial growth and degradation dynamics.

    PubMed

    Woehl, T J; Abellan, P

    2017-02-01

    We present a critical review of methods for defining the chemical environment during liquid cell electron microscopy investigation of electron beam induced nanomaterial growth and degradation. We draw from the radiation chemistry and liquid cell electron microscopy literature to present solution chemistry and electron beam-based methods for selecting the radiolysis products formed and their relative amount during electron irradiation of liquid media in a transmission electron microscope. We outline various methods for establishing net oxidizing or net reducing reaction environments and propose solvents with minimal overall production of radicals under the electron beam. Exemplary liquid cell electron microscopy experiments in the fields of nanoparticle nucleation, growth, and degradation along with recommendations for best practices and experimental parameters are reported. We expect this review will provide researchers with a useful toolkit for designing general chemistry and materials science liquid cell electron microscopy experiments by 'directing' the effect of the electron beam to understand fundamental mechanisms of dynamic nanoscale processes as well as minimizing radiation damage to samples.

  11. Surface radiation budget for climate applications

    NASA Technical Reports Server (NTRS)

    Suttles, J. T. (Editor); Ohring, G. (Editor)

    1986-01-01

    The Surface Radiation Budget (SRB) consists of the upwelling and downwelling radiation fluxes at the surface, separately determined for the broadband shortwave (SW) (0 to 5 micron) and longwave (LW) (greater than 5 microns) spectral regions plus certain key parameters that control these fluxes, specifically, SW albedo, LW emissivity, and surface temperature. The uses and requirements for SRB data, critical assessment of current capabilities for producing these data, and directions for future research are presented.

  12. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1976

    1976-01-01

    Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

  13. Computational chemistry

    NASA Technical Reports Server (NTRS)

    Arnold, J. O.

    1987-01-01

    With the advent of supercomputers, modern computational chemistry algorithms and codes, a powerful tool was created to help fill NASA's continuing need for information on the properties of matter in hostile or unusual environments. Computational resources provided under the National Aerodynamics Simulator (NAS) program were a cornerstone for recent advancements in this field. Properties of gases, materials, and their interactions can be determined from solutions of the governing equations. In the case of gases, for example, radiative transition probabilites per particle, bond-dissociation energies, and rates of simple chemical reactions can be determined computationally as reliably as from experiment. The data are proving to be quite valuable in providing inputs to real-gas flow simulation codes used to compute aerothermodynamic loads on NASA's aeroassist orbital transfer vehicles and a host of problems related to the National Aerospace Plane Program. Although more approximate, similar solutions can be obtained for ensembles of atoms simulating small particles of materials with and without the presence of gases. Computational chemistry has application in studying catalysis, properties of polymers, all of interest to various NASA missions, including those previously mentioned. In addition to discussing these applications of computational chemistry within NASA, the governing equations and the need for supercomputers for their solution is outlined.

  14. Solid State Radiation Dosimeters for Space and Medical Applications

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G. (Editor)

    1996-01-01

    This report describes the development of two radiation monitors (RADMON's) for use in detecting total radiation dose and high-energy particles. These radiation detectors are chip-size devices fabricated in 1.2 micrometer CMOS and have flown in space on both experimental and commercial spacecraft. They have been used to characterize protons and electrons in the Earth's radiation belts, particles from the Sun, and protons used for medical therapy. Having proven useful in a variety of applications, the detector is now being readied for commercialization.

  15. The application of green chemistry methods in organophosphorus synthesis

    NASA Astrophysics Data System (ADS)

    Odinets, Irina L.; Matveeva, E. V.

    2012-03-01

    Data concerning the synthesis of organophosphorus compounds in ionic liquids, in water and under solvent-free conditions are considered and summarized. It is shown that this strategy, which complies with the definition of green chemistry, has advantages in terms of the rate of the process and the yields of target products as compared with syntheses in common organic solvents. The Wittig, Horner-Wadsworth-Emmons, Kabachnik-Fields, Arbuzov and Michaelis reactions are considered as examples. The bibliography includes 178 references.

  16. Application of Stochastic and Deterministic Approaches to Modeling Interstellar Chemistry

    NASA Astrophysics Data System (ADS)

    Pei, Yezhe

    This work is about simulations of interstellar chemistry using the deterministic rate equation (RE) method and the stochastic moment equation (ME) method. Primordial metal-poor interstellar medium (ISM) is of our interest and the socalled “Population-II” stars could have been formed in this environment during the “Epoch of Reionization” in the baby universe. We build a gas phase model using the RE scheme to describe the ionization-powered interstellar chemistry. We demonstrate that OH replaces CO as the most abundant metal-bearing molecule in such interstellar clouds of the early universe. Grain surface reactions play an important role in the studies of astrochemistry. But the lack of an accurate yet effective simulation method still presents a challenge, especially for large, practical gas-grain system. We develop a hybrid scheme of moment equations and rate equations (HMR) for large gas-grain network to model astrochemical reactions in the interstellar clouds. Specifically, we have used a large chemical gas-grain model, with stochastic moment equations to treat the surface chemistry and deterministic rate equations to treat the gas phase chemistry, to simulate astrochemical systems as of the ISM in the Milky Way, the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC). We compare the results to those of pure rate equations and modified rate equations and present a discussion about how moment equations improve our theoretical modeling and how the abundances of the assorted species are changed by varied metallicity. We also model the observed composition of H2O, CO and CO2 ices toward Young Stellar Objects in the LMC and show that the HMR method gives a better match to the observation than the pure RE method.

  17. Spectroscopically Accurate Line Lists for Application in Sulphur Chemistry

    NASA Astrophysics Data System (ADS)

    Underwood, D. S.; Azzam, A. A. A.; Yurchenko, S. N.; Tennyson, J.

    2013-09-01

    Monitoring sulphur chemistry is thought to be of great importance for exoplanets. Doing this requires detailed knowledge of the spectroscopic properties of sulphur containing molecules such as hydrogen sulphide (H2S) [1], sulphur dioxide (SO2), and sulphur trioxide (SO3). Each of these molecules can be found in terrestrial environments, produced in volcano emissions on Earth, and analysis of their spectroscopic data can prove useful to the characterisation of exoplanets, as well as the study of planets in our own solar system, with both having a possible presence on Venus. A complete, high temperature list of line positions and intensities for H32 2 S is presented. The DVR3D program suite is used to calculate the bound ro-vibration energy levels, wavefunctions, and dipole transition intensities using Radau coordinates. The calculations are based on a newly determined, spectroscopically refined potential energy surface (PES) and a new, high accuracy, ab initio dipole moment surface (DMS). Tests show that the PES enables us to calculate the line positions accurately and the DMS gives satisfactory results for line intensities. Comparisons with experiment as well as with previous theoretical spectra will be presented. The results of this study will form an important addition to the databases which are considered as sources of information for space applications; especially, in analysing the spectra of extrasolar planets, and remote sensing studies for Venus and Earth, as well as laboratory investigations and pollution studies. An ab initio line list for SO3 was previously computed using the variational nuclear motion program TROVE [2], and was suitable for modelling room temperature SO3 spectra. The calculations considered transitions in the region of 0-4000 cm-1 with rotational states up to J = 85, and includes 174,674,257 transitions. A list of 10,878 experimental transitions had relative intensities placed on an absolute scale, and were provided in a form suitable

  18. A gist of comprehensive review of hadronic chemistry and its applications

    SciTech Connect

    Tangde, Vijay M.

    2015-03-10

    20{sup th} century theories of Quantum Mechanics and Quantum Chemistry are exactly valid only when considered to represent the atomic structures. While considering the more general aspects of atomic combinations these theories fail to explain all the related experimental data from first unadulterated axiomatic principles. According to Quantum Chemistry two valence electrons should repel each other and as such there is no mathematical representation of a strong attractive forces between such valence electrons. In view of these and other insufficiencies of Quantum Chemistry, an Italian-American Scientist Professor Ruggero Maria Santilli during his more than five decades of dedicated and sustained research has denounced the fact that quantum chemistry is mostly based on mere nomenclatures. Professor R M Santilli first formulated the iso-, geno- and hyper- mathematics [1, 2, 3, 4] that helped in understanding numerous diversified problems and removing inadequacies in most of the established and celebrated theories of 20th century physics and chemistry. This involves the isotopic, genotopic, etc. lifting of Lie algebra that generated Lie admissible mathematics to properly describe irreversible processes. The studies on Hadronic Mechanics in general and chemistry in particular based on Santilli’s mathematics[3, 4, 5] for the first time has removed the very fundamental limitations of quantum chemistry [2, 6, 7, 8]. In the present discussion, a comprehensive review of Hadronic Chemistry is presented that imparts the completeness to the Quantum Chemistry via an addition of effects at distances of the order of 1 fm (only) which are assumed to be Non-linear, Non-local, Non-potential, Non-hamiltonian and thus Non-unitary, stepwise successes of Hadronic Chemistry and its application in development of a new chemical species called Magnecules.

  19. Radiation Hydrodynamics: Numerical Aspects and Applications

    NASA Astrophysics Data System (ADS)

    Dorfi, Ernst A.

    Introduction General Remarks on the Numerical Method Time Scales Length Scales Interaction Between Matter and Radiation Moving Fronts Basic Equations Radiation Hydrodynamics (RHD) Coupling Terms Closure Condition Opacity Equation of State Transport Theorem Solution Strategy Integral Form of the RHD Equations Symbolic Notation Moving Coordinates Implicit Discretization Time-centering Adaptive RHD Equations Discretization of Gradients and Divergence Terms Diffusion Advection Initial Conditions Boundary Conditions Artificial Viscosity Discrete RHD Equations Radiative Closure Condition Radiative Boundary Conditions Eddington Factor Adaptive Grids Basic Grid Properties Desired Resolution Spatial and Temporal Smoothing Grid Equation Grid Boundary Conditions Grid Motion Remarks on the Grid Equation First Example: Simple Test Function Second Example: Shock Tube Problem Initial Grid Distributions Further Computational Needs Rational Spline Interpolation CPU-Time Requirements Iteration Procedure and Matrix Inversion Structure of the Jacobi Matrix Time-Step Control Computational Examples Evolution of Supernova Remnants (SNRs) Nonlinear Stellar Pulsations Protostellar Collapse Dust-Driven Winds Radiative Transfer Discussion Internal Accuracy Problems Advantages and Disadvantages of the implict formulation Nuclear and Chemical Networks and Convection Multidimensional Versions Improvements and Further Recommendations References

  20. Radiation transport Part B: Applications with examples

    SciTech Connect

    Beutler, D.E.

    1997-06-01

    In the previous sections Len Lorence has described the need, theory, and types of radiation codes that can be applied to model the results of radiation effects tests or working environments for electronics. For the rest of this segment, the author will concentrate on the specific ways the codes can be used to predict device response or analyze radiation test results. Regardless of whether one is predicting responses in a working or test environment, the procedures are virtually the same. The same can be said for the use of 1-, 2-, or 3-dimensional codes and Monte Carlo or discrete ordinates codes. No attempt is made to instruct the student on the specifics of the code. For example, the author will not discuss the details, such as the number of meshes, energy groups, etc. that are appropriate for a discrete ordinates code. For the sake of simplicity, he will restrict himself to the 1-dimensional code CEPXS/ONELD. This code along with a wide variety of other radiation codes can be obtained form the Radiation Safety Information Computational Center (RSICC) for a nominal handling fee.

  1. Clinical applications of continuous infusion chemotherapy ahd concomitant radiation therapy

    SciTech Connect

    Rosenthal, C.J.; Rotman, M.

    1986-01-01

    This book presents information on the following topics: theoretical basis and clinical applications of 5-FU as a radiosensitizer; treatment of hepatic metastases from gastro intestingal primaries with split course radiation therapy; combined modality therapy with 5-FU, Mitomycin-C and radiation therapy for sqamous cell cancers; treatment of bladder carcinoma with concomitant infusion chemotherapy and irradiation; a treatment of invasiv bladder cancer by the XRT/5FU protocol; concomitant radiation therapy and doxorubicin by continuous infusion in advanced malignancies; cis platin by continuous infusion with concurrent radiation therapy in malignant tumors; combination of radiation with concomitant continuous adriamycin infusion in a patient with partially excised pleomorphic soft tissue sarcoma of the lower extremeity; treatment of recurrent carcinoma of the paranasal sinuses using concomitant infusion cis-platinum and radiation therapy; hepatic artery infusion for hepatic metastases in combination with hepatic resection and hepatic radiation; study of simultaneous radiation therapy, continuous infusion, 5FU and bolus mitomycin-C; cancer of the esophagus; continuous infusion VP-16, bolus cis-platinum and simultaneous radiation therapy as salvage therapy in small cell bronchogenic carcinoma; and concomitant radiation, mitomycin-C and 5-FU infusion in gastro intestinal cancer.

  2. Application of Improved Radiation Modeling to General Circulation Models

    SciTech Connect

    Michael J Iacono

    2011-04-07

    This research has accomplished its primary objectives of developing accurate and efficient radiation codes, validating them with measurements and higher resolution models, and providing these advancements to the global modeling community to enhance the treatment of cloud and radiative processes in weather and climate prediction models. A critical component of this research has been the development of the longwave and shortwave broadband radiative transfer code for general circulation model (GCM) applications, RRTMG, which is based on the single-column reference code, RRTM, also developed at AER. RRTMG is a rigorously tested radiation model that retains a considerable level of accuracy relative to higher resolution models and measurements despite the performance enhancements that have made it possible to apply this radiation code successfully to global dynamical models. This model includes the radiative effects of all significant atmospheric gases, and it treats the absorption and scattering from liquid and ice clouds and aerosols. RRTMG also includes a statistical technique for representing small-scale cloud variability, such as cloud fraction and the vertical overlap of clouds, which has been shown to improve cloud radiative forcing in global models. This development approach has provided a direct link from observations to the enhanced radiative transfer provided by RRTMG for application to GCMs. Recent comparison of existing climate model radiation codes with high resolution models has documented the improved radiative forcing capability provided by RRTMG, especially at the surface, relative to other GCM radiation models. Due to its high accuracy, its connection to observations, and its computational efficiency, RRTMG has been implemented operationally in many national and international dynamical models to provide validated radiative transfer for improving weather forecasts and enhancing the prediction of global climate change.

  3. On the Applicability of the Green Chemistry Principles to Sustainability of Organic Matter on Asteroids

    NASA Astrophysics Data System (ADS)

    Kolb, Vera M.

    2010-06-01

    The connection between astrobiology and green chemistry represents a new approach to sustainability of organic matter on asteroids or similar bodies. Green chemistry is chemistry which is environmentally friendly. One obvious way for chemistry to be green is to use water as a solvent, instead of more toxic organic solvents. Many astrobiological reactions occur in the aqueous medium, for example in the prebiotic soup or during the aqueous alteration period on asteroids. Thus any advances in the green organic reactions in water are directly applicable to astrobiology. Another green chemistry approach is to abolish use of toxic solvents. This can be accomplished by carrying out the reactions without a solvent in the solventless or solid-state reactions. The advances in these green reactions are directly applicable to the chemistry on asteroids during the periods when water was not available. Many reactions on asteroids may have been done in the solid mixtures. These reactions may be responsible for a myriad of organic compounds that have been isolated from the meteorites.

  4. Applications of Quantum Chemistry to the Study of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard L.

    2005-01-01

    For several years, scientists at NASA Ames have been studying the properties of carbon nanotubes using various experimental and computational methods. In this talk, I will compare different strategies for using quantum chemistry calculations to describe the electronic structure, deformation and chemical functionalization of single wall carbon nanotubes (SWNT) and the physisorption of small molecules on nanotube surfaces. The SWNT can be treated as an infinite (periodic) or finite length carbon cylinder or as a polycyclic aromatic hydrocarbon (PAH) molecule with an imposed curvature maintained by external constraints (as if it were cut out of the SWNT surface). Calculations are carried out using DFT and MP2 methods and a variety of atomic orbital basis sets from minimal (STO-3G) to valence triple zeta. The optimal approach is based on the particular SWNT property of interest. Examples to be discussed include: nanotube fluorination and other functionalization reactions; coating of nanotubes by water vapor and low-molecular weight organic molecules; and the nature of the interface between SWNT and liquids such as water and amines. In many cases, the quantum chemistry calculations are used to parameterize or validate force fields for molecular dynamics simulations. The results of these calculations have helped explain experimental data and contributed to the design of novel materials and sensors based on carbon nanotubes. Some of this research is described in the following papers:

  5. JPRS Report, Science & Technology, USSR: Chemistry

    DTIC Science & Technology

    2007-11-02

    This report contains foreign media information from the USSR concerning analytical chemistry, electrochemistry, environmental chemistry, inorganic compounds, organophosphorous compounds, polymers (rubber) and radiation chemistry.

  6. Introduction to Chemistry and Applications in Nature of Mass Independent Isotope Effects Special Feature

    PubMed Central

    Thiemens, Mark H.

    2013-01-01

    Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented. PMID:24167299

  7. Introduction to chemistry and applications in nature of mass independent isotope effects special feature.

    PubMed

    Thiemens, Mark H

    2013-10-29

    Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented.

  8. Application of Ion Mobility Spectrometry (IMS) in forensic chemistry and toxicology with focus on biological matrices

    NASA Technical Reports Server (NTRS)

    Bernhard, Werner; Keller, Thomas; Regenscheit, Priska

    1995-01-01

    The IMS (Ion Mobility Spectroscopy) instrument 'Ionscan' takes advantage of the fact that trace quantities of illicit drugs are adsorbed on dust particles on clothes, in cars and on other items of evidence. The dust particles are collected on a membrane filter by a special attachment on a vacuum cleaner. The sample is then directly inserted into the spectrometer and can be analyzed immediately. We show casework applications of a forensic chemistry and toxicology laboratory. One new application of IMS in forensic chemistry is the detection of psilocybin in dried mushrooms without any further sample preparation.

  9. Applications of organoboron compounds in carbohydrate chemistry and glycobiology: analysis, separation, protection, and activation.

    PubMed

    McClary, Corey A; Taylor, Mark S

    2013-11-15

    The reversible covalent interactions between organoboron compounds and diols have been applied for many years in carbohydrate chemistry. They form the basis of efficient methods for the detection of carbohydrates, and applications in cellular imaging and glycoprotein analysis are beginning to emerge. The interactions are also of widespread utility in carbohydrate synthesis: depending upon the coordination geometry at boron, either protection or activation of a bound diol motif may be achieved. This review article uses recent examples to illustrate the breadth of applications of organoboron compounds in carbohydrate chemistry.

  10. The effects of metallicity, UV radiation and non-equilibrium chemistry in high-resolution simulations of galaxies

    NASA Astrophysics Data System (ADS)

    Richings, A. J.; Schaye, Joop

    2016-05-01

    We present a series of hydrodynamic simulations of isolated galaxies with stellar mass of 109 M⊙. The models use a resolution of 750 M⊙ per particle and include a treatment for the full non-equilibrium chemical evolution of ions and molecules (157 species in total), along with gas cooling rates computed self-consistently using the non-equilibrium abundances. We compare these to simulations evolved using cooling rates calculated assuming chemical (including ionization) equilibrium, and we consider a wide range of metallicities and UV radiation fields, including a local prescription for self-shielding by gas and dust. We find higher star formation rates and stronger outflows at higher metallicity and for weaker radiation fields, as gas can more easily cool to a cold (few hundred Kelvin) star-forming phase under such conditions. Contrary to variations in the metallicity and the radiation field, non-equilibrium chemistry generally has no strong effect on the total star formation rates or outflow properties. However, it is important for modelling molecular outflows. For example, the mass of H2 outflowing with velocities {>}50 {km} {s}^{-1} is enhanced by a factor ˜20 in non-equilibrium. We also compute the observable line emission from C II and CO. Both are stronger at higher metallicity, while C II and CO emission are higher for stronger and weaker radiation fields, respectively. We find that C II is generally unaffected by non-equilibrium chemistry. However, emission from CO varies by a factor of ˜2-4. This has implications for the mean XCO conversion factor between CO emission and H2 column density, which we find is lowered by up to a factor ˜2.3 in non-equilibrium, and for the fraction of CO-dark molecular gas.

  11. A steerable radiator for spacecraft application

    NASA Technical Reports Server (NTRS)

    Heizer, B. L.; Goo, S. D.; Rhodes, G. D.; Thoreson, D. W.; Parish, R. C.

    1986-01-01

    Future large space structures such as the Space Station will have high dissipation and long life requirements which dictate the requirements for steerable radiators. Several rotary coupling concepts were considered to accomplish heat transport across the steerable radiator system's rotating interface. Rotary fluid couplings were chosen over rotary contact couplings or flexible lines because of low temperature gradients and operational flexibility. A rotary fluid coupling has been designed for use on initial operating capability (IOC) and growth Space Station. Its internal seals have been demonstrated to a 10 year life with minimal (0.055 lbm NH3/year) leakage between internal passages. Materials compatibility tests have been conducted to demonstrate compatibility with ammonia. A seal leakage management system has been designed to: (1) monitor pressures between the internal seals, (2) remove leakage, and (3) store the leakage fluid in a reservoir.

  12. Radiation immobilization of catalase and its application

    NASA Astrophysics Data System (ADS)

    Guanghui, Wang; Hongfei, Ha; Xia, Wang; Jilan, Wu

    Catalase was immobilized by chemical method on porous polyacrylamide particles which produced through radiation polymerization of acrylamide monomer at low temperature (-78°C). Activity of immobilized catalase was enhanced distinctly by joining a chemical "arm" to the support. The method of recovery of catalase activity on immobilized polymer was found by soaking it in certain buffer. The treatment of H 2O 2 both in aqueous solution and alcoholic solution by using the immobilized catalase was performed.

  13. Application of radiation technology in vaccines development

    PubMed Central

    2015-01-01

    One of the earliest methods used in the manufacture of stable and safe vaccines is the use of chemical and physical treatments to produce inactivated forms of pathogens. Although these types of vaccines have been successful in eliciting specific humoral immune responses to pathogen-associated immunogens, there is a large demand for the development of fast, safe, and effective vaccine manufacturing strategies. Radiation sterilization has been used to develop a variety of vaccine types, because it can eradicate chemical contaminants and penetrate pathogens to destroy nucleic acids without damaging the pathogen surface antigens. Nevertheless, irradiated vaccines have not widely been used at an industrial level because of difficulties obtaining the necessary equipment. Recent successful clinical trials of irradiated vaccines against pathogens and tumors have led to a reevaluation of radiation technology as an alternative method to produce vaccines. In the present article, we review the challenges associated with creating irradiated vaccines and discuss potential strategies for developing vaccines using radiation technology. PMID:26273573

  14. Biological applications of synchrotron radiation infrared spectromicroscopy.

    PubMed

    Marcelli, Augusto; Cricenti, Antonio; Kwiatek, Wojciech M; Petibois, Cyril

    2012-01-01

    Extremely brilliant infrared (IR) beams provided by synchrotron radiation sources are now routinely used in many facilities with available commercial spectrometers coupled to IR microscopes. Using these intense non-thermal sources, a brilliance two or three order of magnitude higher than a conventional source is achievable through small pinholes (<10 μm) with a high signal to-noise ratio. IR spectroscopy is a powerful technique to investigate biological systems and offers many new imaging opportunities. The field of infrared biological imaging covers a wide range of fundamental issues and applied researches such as cell imaging or tissue imaging. Molecular maps with a spatial resolution down to the diffraction limit may be now obtained with a synchrotron radiation IR source also on thick samples. Moreover, changes of the protein structure are detectable in an IR spectrum and cellular molecular markers can be identified and used to recognize a pathological status of a tissue. Molecular structure and functions are strongly correlated and this aspect is particularly relevant for imaging. We will show that the brilliance of synchrotron radiation IR sources may enhance the sensitivity of a molecular signal obtained from small biosamples, e.g., a single cell, containing extremely small amounts of organic matter. We will also show that SR IR sources allow to study chemical composition and to identify the distribution of organic molecules in cells at submicron resolution is possible with a high signal-to-noise ratio. Moreover, the recent availability of two-dimensional IR detectors promises to push forward imaging capabilities in the time domain. Indeed, with a high current synchrotron radiation facility and a Focal Plane Array the chemical imaging of individual cells can be obtained in a few minutes. Within this framework important results are expected in the next years using synchrotron radiation and Free Electron Laser (FEL) sources for spectro-microscopy and spectral

  15. Microfluidics: applications for analytical purposes in chemistry and biochemistry.

    PubMed

    Ohno, Ken-ichi; Tachikawa, Kaoru; Manz, Andreas

    2008-11-01

    In this review, we present recent advancements and novel developments in fluidic systems for applied analytical purposes in chemistry, biochemistry, and life science in general that employ and reflect the full benefits of microfluidics. A staggering rise in publications related to integrated, all-in-one microfluidic chips capable of separation, reaction, and detection have been observed, all of which realise the principal of micro total analysis systems or lab-on-a-chip. These integrated chips actively adopt the scaling law concepts, utilising the highly developed fabrication techniques. Their aim is to multi-functionalise and fully automate devices believed to assist the future advancements of point-of-care, clinical, and medical diagnostics.

  16. Physico-chemical aspects of the drugs radiation sterilization in commercial packing (applied scientific problems of radiation pharmaceutical chemistry)

    SciTech Connect

    Safarov, S.A.

    1993-12-31

    The results of studies on the simultaneous radiosterilization of direct and bifurcational trachea prostheses made of silicon-organic rubber of soft elastic consistency, with polyethylenterephthalate and polyamid cuffs, and radiation chemical grafting of polymeric layer and linking with functional groups of the graft sulfanilamide and antibiotics layer are discussed. Radiopharmaceuticals are also described.

  17. Application of Optical Imaging and Spectroscopy to Radiation Biology

    PubMed Central

    Palmer, Gregory M.; Vishwanath, Karthik; Dewhirst, Mark W.

    2013-01-01

    Optical imaging and spectroscopy is a diverse field that has been of critical importance in a wide range of areas in radiation research. It is capable of spanning a wide range of spatial and temporal scales, and has the sensitivity and specificity needed for molecular and functional imaging. This review will describe the basic principles of optical imaging and spectroscopy, highlighting a few relevant applications to radiation research. PMID:22360397

  18. Radiation Issues and Applications of Floating Gate Memories

    NASA Technical Reports Server (NTRS)

    Scheick, L. Z.; Nguyen, D. N.

    2000-01-01

    The radiation effects that affect various systems that comprise floating gate memories are presented. The wear-out degradation results of unirradiated flash memories are compared to irradiated flash memories. The procedure analyzes the failure to write and erase caused by wear-out and degradation of internal charge pump circuits. A method is described for characterizing the radiation effects of the floating gate itself. The rate dependence, stopping power dependence, SEU susceptibility and applications of floating gate in radiation environment are presented. The ramifications for dosimetry and cell failure are discussed as well as for the long term use aspects of non-volatile memories.

  19. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields, volume 1

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1991-01-01

    The following subject areas are covered: the development of detailed nonequilibrium radiation models for molecules along with appropriate models for atoms; the inclusion of nongray radiation gasdynamic coupling in the VSL (Viscous Shock Layer) code; the development and evaluation of various electron-electronic energy models; and an examination of the effects of shock slip.

  20. Radiation protection and dosimetry issues in the medical applications of ionizing radiation

    NASA Astrophysics Data System (ADS)

    Vaz, Pedro

    2014-11-01

    The technological advances that occurred during the last few decades paved the way to the dissemination of CT-based procedures in radiology, to an increasing number of procedures in interventional radiology and cardiology as well as to new techniques and hybrid modalities in nuclear medicine and in radiotherapy. These technological advances encompass the exposure of patients and medical staff to unprecedentedly high dose values that are a cause for concern due to the potential detrimental effects of ionizing radiation to the human health. As a consequence, new issues and challenges in radiological protection and dosimetry in the medical applications of ionizing radiation have emerged. The scientific knowledge of the radiosensitivity of individuals as a function of age, gender and other factors has also contributed to raising the awareness of scientists, medical staff, regulators, decision makers and other stakeholders (including the patients and the public) for the need to correctly and accurately assess the radiation induced long-term health effects after medical exposure. Pediatric exposures and their late effects became a cause of great concern. The scientific communities of experts involved in the study of the biological effects of ionizing radiation have made a strong case about the need to undertake low dose radiation research and the International System of Radiological Protection is being challenged to address and incorporate issues such as the individual sensitivities, the shape of dose-response relationship and tissue sensitivity for cancer and non-cancer effects. Some of the answers to the radiation protection and dosimetry issues and challenges in the medical applications of ionizing radiation lie in computational studies using Monte Carlo or hybrid methods to model and simulate particle transport in the organs and tissues of the human body. The development of sophisticated Monte Carlo computer programs and voxel phantoms paves the way to an accurate

  1. Uniqueness of Zinc as a Bioelement: Principles and Applications in Bioinorganic Chemistry--III.

    ERIC Educational Resources Information Center

    Ochiai, Ei-Ichiro

    1988-01-01

    Attempts to delineate certain basic principles and applications of bioinorganic chemistry to oxidation-reduction reactions. Examines why zinc(II) is so uniquely suited to enzymated reactions of the acid-base type. Suggests the answer may be in the natural abundance and the basic physicochemical properties of zinc(II). (MVL)

  2. Modeling hot spring chemistries with applications to martian silica formation

    USGS Publications Warehouse

    Marion, G.M.; Catling, D.C.; Crowley, J.K.; Kargel, J.S.

    2011-01-01

    Many recent studies have implicated hydrothermal systems as the origin of martian minerals across a wide range of martian sites. Particular support for hydrothermal systems include silica (SiO2) deposits, in some cases >90% silica, in the Gusev Crater region, especially in the Columbia Hills and at Home Plate. We have developed a model called CHEMCHAU that can be used up to 100??C to simulate hot springs associated with hydrothermal systems. The model was partially derived from FREZCHEM, which is a colder temperature model parameterized for broad ranges of temperature (<-70 to 25??C), pressure (1-1000 bars), and chemical composition. We demonstrate the validity of Pitzer parameters, volumetric parameters, and equilibrium constants in the CHEMCHAU model for the Na-K-Mg-Ca-H-Cl-ClO4-SO4-OH-HCO3-CO3-CO2-O2-CH4-Si-H2O system up to 100??C and apply the model to hot springs and silica deposits.A theoretical simulation of silica and calcite equilibrium shows how calcite is least soluble with high pH and high temperatures, while silica behaves oppositely. Such influences imply that differences in temperature and pH on Mars could lead to very distinct mineral assemblages. Using measured solution chemistries of Yellowstone hot springs and Icelandic hot springs, we simulate salts formed during the evaporation of two low pH cases (high and low temperatures) and a high temperature, alkaline (high pH) sodic water. Simulation of an acid-sulfate case leads to precipitation of Fe and Al minerals along with silica. Consistency with martian mineral assemblages suggests that hot, acidic sulfate solutions are plausibility progenitors of minerals in the past on Mars. In the alkaline pH (8.45) simulation, formation of silica at high temperatures (355K) led to precipitation of anhydrous minerals (CaSO4, Na2SO4) that was also the case for the high temperature (353K) low pH case where anhydrous minerals (NaCl, CaSO4) also precipitated. Thus we predict that secondary minerals associated with

  3. Modeling hot spring chemistries with applications to martian silica formation

    NASA Astrophysics Data System (ADS)

    Marion, G. M.; Catling, D. C.; Crowley, J. K.; Kargel, J. S.

    2011-04-01

    Many recent studies have implicated hydrothermal systems as the origin of martian minerals across a wide range of martian sites. Particular support for hydrothermal systems include silica (SiO 2) deposits, in some cases >90% silica, in the Gusev Crater region, especially in the Columbia Hills and at Home Plate. We have developed a model called CHEMCHAU that can be used up to 100 °C to simulate hot springs associated with hydrothermal systems. The model was partially derived from FREZCHEM, which is a colder temperature model parameterized for broad ranges of temperature (<-70 to 25 °C), pressure (1-1000 bars), and chemical composition. We demonstrate the validity of Pitzer parameters, volumetric parameters, and equilibrium constants in the CHEMCHAU model for the Na-K-Mg-Ca-H-Cl-ClO 4-SO 4-OH-HCO 3-CO 3-CO 2-O 2-CH 4-Si-H 2O system up to 100 °C and apply the model to hot springs and silica deposits. A theoretical simulation of silica and calcite equilibrium shows how calcite is least soluble with high pH and high temperatures, while silica behaves oppositely. Such influences imply that differences in temperature and pH on Mars could lead to very distinct mineral assemblages. Using measured solution chemistries of Yellowstone hot springs and Icelandic hot springs, we simulate salts formed during the evaporation of two low pH cases (high and low temperatures) and a high temperature, alkaline (high pH) sodic water. Simulation of an acid-sulfate case leads to precipitation of Fe and Al minerals along with silica. Consistency with martian mineral assemblages suggests that hot, acidic sulfate solutions are plausibility progenitors of minerals in the past on Mars. In the alkaline pH (8.45) simulation, formation of silica at high temperatures (355 K) led to precipitation of anhydrous minerals (CaSO 4, Na 2SO 4) that was also the case for the high temperature (353 K) low pH case where anhydrous minerals (NaCl, CaSO 4) also precipitated. Thus we predict that secondary

  4. Galactic cosmic radiation model and its applications.

    PubMed

    Badhwar, G D; O'Neill, P M

    1996-01-01

    A model for the differential energy spectra of galactic cosmic radiation as a function of solar activity is described. It is based on the standard diffusion-convection theory of solar modulation. Estimates of the modulation potential based on fitting this theory to observed spectral measurements from 1954 to 1989 are correlated to the Climax neutron counting rates and to the sunspot numbers at earlier times taking into account the polarity of the interplanetary magnetic field at the time of observations. These regression lines then provide a method for predicting the modulation at later times. The results of this model are quantitatively compared to a similar Moscow State University (MSU) model. These model cosmic ray spectra are used to predict the linear energy transfer spectra, differential energy spectra of light (charge < or = 2) ions, and single event upset rates in memory devices. These calculations are compared to observations made aboard the Space Shuttle.

  5. Design of a compact ring for proton radiation applications

    NASA Astrophysics Data System (ADS)

    Li, Guang-Rui; Zheng, Shu-Xin; Yao, Hong-Juan; Guan, Xia-Ling; Wang, Xue-Wu; Huang, Wen-Hui

    2017-01-01

    This paper presents the design of a compact proton synchrotron, including lattice structure, injection system and extraction system, for radiation applications. The lattice is based on a DBFO cell and shows good properties like small β max and decent kick arm. Radiation applications require relative strong and continuous beam, so we propose strip injection and resonance extraction for the design. A phase space painting scheme is designed and simulated by ORBIT. The scheme achieves good uniformity in phase space. The extraction system is designed and optimized by multi-particle tracking.

  6. Novel applications of light hydrocarbons chemistry in petroleum exploration

    SciTech Connect

    Mango, F.D. )

    1991-03-01

    The light hydrocarbons in petroleum are products of a kerogen-specific catalytic process. The catalysts are believed to be the transition metals entrained in kerogen. The process is controlled by the metals in the active sites and the kerogenous organic structures surrounding the active sites. Different catalytic sites are suggested to yield distinct distributions of light hydrocarbons. The author recognizes three dominant (primary) distributions, with all other distributions adequately represented by some linear combination of the three primary distributions. Three catalytic sites, therefore, can be associated with the generation of light hydrocarbons. He introduces a simple and inexpensive procedure using cross plots of various product ratios to correlate oils and source rocks. It has proven to be a remarkably articulate and powerful tool for deconvoluting diverse oils into genetic groups. The light hydrocarbons are also indicators of oil-generation temperature and other physical parameters associated with oil generation. The analysis of light hydrocarbons from this perspective is new. It provides the exploration geochemist with a novel technique for gaining insight into the fundamental chemistry of petroleum generation.

  7. Applications and Methods for Continuous Monitoring of Physiological Chemistry

    DTIC Science & Technology

    2016-02-04

    a platform methodology to clone, evolve, purify and stabilize high activity oxidase enzymes that are suitable for point-of-care diagnostic and human ...evolve, purify and stabilize high activity oxidase enzymes that are suitable for point-of-care diagnostic and human biosensor applications. The...suitable for POCs and human biosensor applications. This was accomplished by demonstrating that the addition of fusion proteins to wild type oxidase

  8. Ab initio Quantum Chemical Reaction Kinetics: Recent Applications in Combustion Chemistry (Briefing Charts)

    DTIC Science & Technology

    2015-06-28

    Charts 3. DATES COVERED (From - To) June 2015-June 2015 4. TITLE AND SUBTITLE AB INITIO QUANTUM CHEMICAL REACTION KINETICS: RECENT APPLICATIONS IN...Unlimited. 13. SUPPLEMENTARY NOTES Briefing Charts presented at 9th Int. Conf. Chemical Kinetics; Ghent, Belgium; 28 Jun 2015. PA#15351. 14. ABSTRACT...ghanshyam.vaghjiani@us.af.mil Ab initio Quantum Chemical Reaction Kinetics: Recent Applications in Combustion Chemistry Ghanshyam L. Vaghjiani* DISTRIBUTION A

  9. Recent Applications of Carbon-Based Nanomaterials in Analytical Chemistry: Critical Review

    PubMed Central

    Scida, Karen; Stege, Patricia W.; Haby, Gabrielle; Messina, Germán A.; García, Carlos D.

    2011-01-01

    The objective of this review is to provide a broad overview of the advantages and limitations of carbon-based nanomaterials with respect to analytical chemistry. Aiming to illustrate the impact of nanomaterials on the development of novel analytical applications, developments reported in the 2005–2010 period have been included and divided into sample preparation, separation, and detection. Within each section, fullerenes, carbon nanotubes, graphene, and composite materials will be addressed specifically. Although only briefly discussed, included is a section highlighting nanomaterials with interesting catalytic properties that can be used in the design of future devices for analytical chemistry. PMID:21458626

  10. Recent developments and applications of clickable photoprobes in medicinal chemistry and chemical biology.

    PubMed

    Lapinsky, David J; Johnson, Douglas S

    2015-01-01

    Photoaffinity labeling is a well-known biochemical technique that has grown significantly since the turn of the century, principally due to its combination with bioorthogonal/click chemistry reactions. This review highlights new developments and applications of clickable photoprobes in medicinal chemistry and chemical biology. In particular, recent examples of clickable photoprobes for target identification, activity- or affinity-based protein profiling (ABPP or AfBPP), characterization of sterol- or lipid-protein interactions and characterization of ligand-binding sites are presented.

  11. Recent applications of carbon-based nanomaterials in analytical chemistry: critical review.

    PubMed

    Scida, Karen; Stege, Patricia W; Haby, Gabrielle; Messina, Germán A; García, Carlos D

    2011-04-08

    The objective of this review is to provide a broad overview of the advantages and limitations of carbon-based nanomaterials with respect to analytical chemistry. Aiming to illustrate the impact of nanomaterials on the development of novel analytical applications, developments reported in the 2005-2010 period have been included and divided into sample preparation, separation, and detection. Within each section, fullerenes, carbon nanotubes, graphene, and composite materials will be addressed specifically. Although only briefly discussed, included is a section highlighting nanomaterials with interesting catalytic properties that can be used in the design of future devices for analytical chemistry.

  12. Infrared radiation industrial application and economic benefits.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    IR heating has been accepted to be one of the important means for cooking, drying, roasting, baking, blanching and pasteurization of food and agricultural products. This chapter reviews the scientific developments in IR applications, demonstrates the status of selected industrial and pilot scale IR ...

  13. On the Green's function of the partially diffusion-controlled reversible ABCD reaction for radiation chemistry codes

    NASA Astrophysics Data System (ADS)

    Plante, Ianik; Devroye, Luc

    2015-09-01

    Several computer codes simulating chemical reactions in particles systems are based on the Green's functions of the diffusion equation (GFDE). Indeed, many types of chemical systems have been simulated using the exact GFDE, which has also become the gold standard for validating other theoretical models. In this work, a simulation algorithm is presented to sample the interparticle distance for partially diffusion-controlled reversible ABCD reaction. This algorithm is considered exact for 2-particles systems, is faster than conventional look-up tables and uses only a few kilobytes of memory. The simulation results obtained with this method are compared with those obtained with the independent reaction times (IRT) method. This work is part of our effort in developing models to understand the role of chemical reactions in the radiation effects on cells and tissues and may eventually be included in event-based models of space radiation risks. However, as many reactions are of this type in biological systems, this algorithm might play a pivotal role in future simulation programs not only in radiation chemistry, but also in the simulation of biochemical networks in time and space as well.

  14. On the Green's function of the partially diffusion-controlled reversible ABCD reaction for radiation chemistry codes

    SciTech Connect

    Plante, Ianik; Devroye, Luc

    2015-09-15

    Several computer codes simulating chemical reactions in particles systems are based on the Green's functions of the diffusion equation (GFDE). Indeed, many types of chemical systems have been simulated using the exact GFDE, which has also become the gold standard for validating other theoretical models. In this work, a simulation algorithm is presented to sample the interparticle distance for partially diffusion-controlled reversible ABCD reaction. This algorithm is considered exact for 2-particles systems, is faster than conventional look-up tables and uses only a few kilobytes of memory. The simulation results obtained with this method are compared with those obtained with the independent reaction times (IRT) method. This work is part of our effort in developing models to understand the role of chemical reactions in the radiation effects on cells and tissues and may eventually be included in event-based models of space radiation risks. However, as many reactions are of this type in biological systems, this algorithm might play a pivotal role in future simulation programs not only in radiation chemistry, but also in the simulation of biochemical networks in time and space as well.

  15. Validation of elastic cross section models for space radiation applications

    NASA Astrophysics Data System (ADS)

    Werneth, C. M.; Xu, X.; Norman, R. B.; Ford, W. P.; Maung, K. M.

    2017-02-01

    The space radiation field is composed of energetic particles that pose both acute and long-term risks for astronauts in low earth orbit and beyond. In order to estimate radiation risk to crew members, the fluence of particles and biological response to the radiation must be known at tissue sites. Given that the spectral fluence at the boundary of the shielding material is characterized, radiation transport algorithms may be used to find the fluence of particles inside the shield and body, and the radio-biological response is estimated from experiments and models. The fidelity of the radiation spectrum inside the shield and body depends on radiation transport algorithms and the accuracy of the nuclear cross sections. In a recent study, self-consistent nuclear models based on multiple scattering theory that include the option to study relativistic kinematics were developed for the prediction of nuclear cross sections for space radiation applications. The aim of the current work is to use uncertainty quantification to ascertain the validity of the models as compared to a nuclear reaction database and to identify components of the models that can be improved in future efforts.

  16. Radiation Belt Environment Model: Application to Space Weather and Beyond

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching H.

    2011-01-01

    Understanding the dynamics and variability of the radiation belts are of great scientific and space weather significance. A physics-based Radiation Belt Environment (RBE) model has been developed to simulate and predict the radiation particle intensities. The RBE model considers the influences from the solar wind, ring current and plasmasphere. It takes into account the particle drift in realistic, time-varying magnetic and electric field, and includes diffusive effects of wave-particle interactions with various wave modes in the magnetosphere. The RBE model has been used to perform event studies and real-time prediction of energetic electron fluxes. In this talk, we will describe the RBE model equation, inputs and capabilities. Recent advancement in space weather application and artificial radiation belt study will be discussed as well.

  17. Effect of Space Radiation Processing on Lunar Soil Surface Chemistry: X-Ray Photoelectron Spectroscopy Studies

    NASA Technical Reports Server (NTRS)

    Dukes, C.; Loeffler, M.J.; Baragiola, R.; Christoffersen, R.; Keller, J.

    2009-01-01

    Current understanding of the chemistry and microstructure of the surfaces of lunar soil grains is dominated by a reference frame derived mainly from electron microscopy observations [e.g. 1,2]. These studies have shown that the outermost 10-100 nm of grain surfaces in mature lunar soil finest fractions have been modified by the combined effects of solar wind exposure, surface deposition of vapors and accretion of impact melt products [1,2]. These processes produce surface-correlated nanophase Feo, host grain amorphization, formation of surface patinas and other complex changes [1,2]. What is less well understood is how these changes are reflected directly at the surface, defined as the outermost 1-5 atomic monolayers, a region not easily chemically characterized by TEM. We are currently employing X-ray Photoelectron Spectroscopy (XPS) to study the surface chemistry of lunar soil samples that have been previously studied by TEM. This work includes modification of the grain surfaces by in situ irradiation with ions at solar wind energies to better understand how irradiated surfaces in lunar grains change their chemistry once exposed to ambient conditions on earth.

  18. Applications of monolithic columns in liquid chromatography-based clinical chemistry assays.

    PubMed

    Bunch, Dustin R; Wang, Sihe

    2011-08-01

    Monolithic columns have slowly been applied to HPLC methods for clinical chemistry testing in the last 10 years. The application areas include therapeutic drug monitoring, drugs of abuse, vitamins, porphyrins, and steroids. In comparison with conventional particulate columns, the monolithic columns may offer shorter chromatography time, more robustness, and better resolution for certain analytes. The potential drawback of large mobile phase consumption may be improved with smaller id columns, which are currently on the market. Methods covered in this review are those searchable in PubMed up to December 2010. This review highlights the emergence of monolithic column technology in HPLC methods used for clinical chemistry testing. The goals of this review are threefold: (i) To identify the areas of clinical chemistry that analytical monolithic columns have been used in HPLC methods. (ii) To demonstrate the application of analytical monolithic columns in HPLC methods using different detection systems. (iii) To discuss the advantages and limitations of the monolithic columns compared with particulate columns in the clinical chemistry applications.

  19. Infrared Synchrotron Radiation instrumentation and applications

    SciTech Connect

    Hirschmugl, C.

    1991-12-31

    Infrared Synchrotron Radiation (IRSR) is a blossoming field which has three working beamlines, U4IR at the National Synchrotron Light Source, Brookhaven National Laboratory, USA, and two at the Institute of Molecular Sciences in Okasaki, Japan with extensive research projects. There are also several new beamlines in the planning and development stages, both in the United States and abroad. IRSR offers a unique way to access the far infrared (30 {mu} to approx 1 mm) which is a notoriously difficult region to work in. In particular, experiments that demand high brightness are well suited to IRSR just as they are in the x-ray region. The central issue in all of the experiments to data has been good signal to noise, which has been the focus of the instrumentation improvements at the U4IR beamline. A commercial Fourier transform instrument was the chosen spectrometer. Then modifications were made in order to expand the usable region of the existing experiments, in both the far and near infrared. As an example of the performance of this beamline, I will focus on the reflection absorption spectroscopy results for adsorbates on clean surfaces in ultra-high vacuum. 15 refs.

  20. Infrared Synchrotron Radiation instrumentation and applications

    SciTech Connect

    Hirschmugl, C. . Dept. of Applied Physics)

    1991-01-01

    Infrared Synchrotron Radiation (IRSR) is a blossoming field which has three working beamlines, U4IR at the National Synchrotron Light Source, Brookhaven National Laboratory, USA, and two at the Institute of Molecular Sciences in Okasaki, Japan with extensive research projects. There are also several new beamlines in the planning and development stages, both in the United States and abroad. IRSR offers a unique way to access the far infrared (30 {mu} to approx 1 mm) which is a notoriously difficult region to work in. In particular, experiments that demand high brightness are well suited to IRSR just as they are in the x-ray region. The central issue in all of the experiments to data has been good signal to noise, which has been the focus of the instrumentation improvements at the U4IR beamline. A commercial Fourier transform instrument was the chosen spectrometer. Then modifications were made in order to expand the usable region of the existing experiments, in both the far and near infrared. As an example of the performance of this beamline, I will focus on the reflection absorption spectroscopy results for adsorbates on clean surfaces in ultra-high vacuum. 15 refs.

  1. PMMA/MWCNT nanocomposite for proton radiation shielding applications

    NASA Astrophysics Data System (ADS)

    Li, Zhenhao; Chen, Siyuan; Nambiar, Shruti; Sun, Yonghai; Zhang, Mingyu; Zheng, Wanping; Yeow, John T. W.

    2016-06-01

    Radiation shielding in space missions is critical in order to protect astronauts, spacecraft and payloads from radiation damage. Low atomic-number materials are efficient in shielding particle-radiation, but they have relatively weak material properties compared to alloys that are widely used in space applications as structural materials. However, the issues related to weight and the secondary radiation generation make alloys not suitable for space radiation shielding. Polymers, on the other hand, can be filled with different filler materials for reinforcement of material properties, while at the same time provide sufficient radiation shielding function with lower weight and less secondary radiation generation. In this study, poly(methyl-methacrylate)/multi-walled carbon nanotube (PMMA/MWCNT) nanocomposite was fabricated. The role of MWCNTs embedded in PMMA matrix, in terms of radiation shielding effectiveness, was experimentally evaluated by comparing the proton transmission properties and secondary neutron generation of the PMMA/MWCNT nanocomposite with pure PMMA and aluminum. The results showed that the addition of MWCNTs in PMMA matrix can further reduce the secondary neutron generation of the pure polymer, while no obvious change was found in the proton transmission property. On the other hand, both the pure PMMA and the nanocomposite were 18%-19% lighter in weight than aluminum for stopping the protons with the same energy and generated up to 5% fewer secondary neutrons. Furthermore, the use of MWCNTs showed enhanced thermal stability over the pure polymer, and thus the overall reinforcement effects make MWCNT an effective filler material for applications in the space industry.

  2. Click Chemistry Mediated Functionalization of Vertical Nanowires for Biological Applications.

    PubMed

    Vutti, Surendra; Schoffelen, Sanne; Bolinsson, Jessica; Buch-Månson, Nina; Bovet, Nicolas; Nygård, Jesper; Martinez, Karen L; Meldal, Morten

    2016-01-11

    Semiconductor nanowires (NWs) are gaining significant importance in various biological applications, such as biosensing and drug delivery. Efficient and controlled immobilization of biomolecules on the NW surface is crucial for many of these applications. Here, we present for the first time the use of the Cu(I) -catalyzed alkyne-azide cycloaddition and its strain-promoted variant for the covalent functionalization of vertical NWs with peptides and proteins. The potential of the approach was demonstrated in two complementary applications of measuring enzyme activity and protein binding, which is of general interest for biological studies. The attachment of a peptide substrate provided NW arrays for the detection of protease activity. In addition, green fluorescent protein was immobilized in a site-specific manner and recognized by antibody binding to demonstrate the proof-of-concept for the use of covalently modified NWs for diagnostic purposes using minute amounts of material.

  3. Application of click chemistry conditions for 5-bromo-2'-deoxyuridine determination through Fenton and related reactions.

    PubMed

    Cappella, Paolo; Pulici, Maurizio; Gasparri, Fabio

    2015-01-05

    Mixtures of ascorbate and copper used in certain click chemistry experimental conditions act as oxidizing agents, catalyzing the formation of reactive oxygen species through Fenton and related reactions. Hydroxyl radicals act as chemical nucleases, introducing DNA strand breaks that can be exploited for BrdU immunostaining in place of acid denaturation. This procedure is readily applicable to high content analysis and flow cytometry assays, and provides results comparable to click chemistry EdU cycloaddition and classical BrdU immunodetection. Importantly, this approach allows preservation of labile epitopes such as phosphoproteins. This unit describes an optimized method that successfully employs Fenton chemistry for simultaneous detection of phosphoproteins and BrdU in intact cells.

  4. Autonomous RF Radiation Package for Various Applications

    DTIC Science & Technology

    2005-06-01

    integrated unit, including the batteries, power supply, Marx generator, and plug and play antennas for various applications. ARC Technology has...designed the Marx generator and its associated high voltage antennas for this effort. Previous work by ARC has demonstrated 75 mm diameter, 700 mm length...diameter Marx generators capable of delivering 200 kV pulses into 50 coaxial cable with sub-nanosecond risetimes, enabling it to drive an antenna and

  5. See the Light! A Nice Application of Calculus to Chemistry

    ERIC Educational Resources Information Center

    Boersma, Stuart; McGowan, Garrett

    2007-01-01

    Some simple modeling with Riemann sums can be used to develop Beer's Law, which describes the relationship between the absorbance of light and the concentration of the solution which the light is penetrating. A further application of the usefulness of Beer's Law in creating calibration curves is also presented. (Contains 3 figures.)

  6. Analytical Applications of NMR: Summer Symposium on Analytical Chemistry.

    ERIC Educational Resources Information Center

    Borman, Stuart A.

    1982-01-01

    Highlights a symposium on analytical applications of nuclear magnetic resonance spectroscopy (NMR), discussing pulse Fourier transformation technique, two-dimensional NMR, solid state NMR, and multinuclear NMR. Includes description of ORACLE, an NMR data processing system at Syracuse University using real-time color graphics, and algorithms for…

  7. Assessing application vulnerability to radiation-induced SEUs in memory

    NASA Technical Reports Server (NTRS)

    Springer, P. L.

    2001-01-01

    One of the goals of the Remote Exploration and Experimentation (REE) project at JPL is to determine how vulnerable applications are to single event upsets (SEUs) when run in low radiation space environments using commercial-off-the-shelf (COTS) components.

  8. Polyoxazoline: chemistry, properties, and applications in drug delivery.

    PubMed

    Viegas, Tacey X; Bentley, Michael D; Harris, J Milton; Fang, Zhihao; Yoon, Kunsang; Dizman, Bekir; Weimer, Rebecca; Mero, Anna; Pasut, Gianfranco; Veronese, Francesco M

    2011-05-18

    , serum chemistry, organ weights, and the histopathology of key organs were normal. These results conclude that POZ has the desired drug delivery properties for a new biopolymer.

  9. Application of stochastic radiative transfer to remote sensing of vegetation

    NASA Astrophysics Data System (ADS)

    Shabanov, Nikolay V.

    2002-01-01

    The availability of high quality remote sensing data during the past decade provides an impetus for the development of methods that facilitate accurate retrieval of structural and optical properties of vegetation required for the study of global vegetation dynamics. Empirical and statistical methods have proven to be quite useful in many applications, but they often do not shed light on the underlying physical processes. Approaches based on radiative transfer and the physics of matter-energy interaction are therefore required to gain insight into the mechanisms responsible for signal generation. The goal of this dissertation is the development of advanced methods based on radiative transfer for the retrieval of biophysical information from satellite data. Classical radiative transfer theory is applicable to homogeneous vegetation and is generally inaccurate in characterizing the radiation regime in natural vegetation communities, such as forests or woodlands. A stochastic approach to radiative transfer was introduced in this dissertation to describe the radiation regime in discontinuous vegetation canopies. The resulting stochastic model was implemented and tested with field data and Monte Carlo simulations. The effect of gaps on radiation fluxes in vegetation canopies was quantified analytically and compared to classical representations. Next, the stochastic theory was applied to vegetation remote sensing in two case studies. First, the radiative transfer principles underlying an algorithm for leaf area index (LAI) retrieval were studied with data from Harvard Forest. The classical expression for uncollided radiation was modified according to stochastic principles to explain radiometric measurements and vegetation structure. In the second case study, vegetation dynamics in the northern latitudes inferred from the Pathfinder Advanced Very High-Resolution Radiometer Land data were investigated. The signatures of interannual and seasonal variation recorded in the

  10. Computational chemistry for graphene-based energy applications: progress and challenges

    NASA Astrophysics Data System (ADS)

    Hughes, Zak E.; Walsh, Tiffany R.

    2015-04-01

    Research in graphene-based energy materials is a rapidly growing area. Many graphene-based energy applications involve interfacial processes. To enable advances in the design of these energy materials, such that their operation, economy, efficiency and durability is at least comparable with fossil-fuel based alternatives, connections between the molecular-scale structure and function of these interfaces are needed. While it is experimentally challenging to resolve this interfacial structure, molecular simulation and computational chemistry can help bridge these gaps. In this Review, we summarise recent progress in the application of computational chemistry to graphene-based materials for fuel cells, batteries, photovoltaics and supercapacitors. We also outline both the bright prospects and emerging challenges these techniques face for application to graphene-based energy materials in future.

  11. Computational chemistry for graphene-based energy applications: progress and challenges.

    PubMed

    Hughes, Zak E; Walsh, Tiffany R

    2015-04-28

    Research in graphene-based energy materials is a rapidly growing area. Many graphene-based energy applications involve interfacial processes. To enable advances in the design of these energy materials, such that their operation, economy, efficiency and durability is at least comparable with fossil-fuel based alternatives, connections between the molecular-scale structure and function of these interfaces are needed. While it is experimentally challenging to resolve this interfacial structure, molecular simulation and computational chemistry can help bridge these gaps. In this Review, we summarise recent progress in the application of computational chemistry to graphene-based materials for fuel cells, batteries, photovoltaics and supercapacitors. We also outline both the bright prospects and emerging challenges these techniques face for application to graphene-based energy materials in future.

  12. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields, volume 3

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1991-01-01

    The computer programs developed to calculate the shock wave precursor and the method of using them are described. This method calculated the precursor flow field in a nitrogen gas including the effects of emission and absorption of radiation on the energy and composition of gas. The radiative transfer is calculated including the effects of absorption and emission through the line as well as the continuum process in the shock layer and through the continuum processes only in the precursor. The effects of local thermodynamic nonequilibrium in the shock layer and precursor regions are also included in the radiative transfer calculations. Three computer programs utilized by this computational scheme to calculate the precursor flow field solution for a given shock layer flow field are discussed.

  13. Parallelism in computational chemistry: Applications in quantum and statistical mechanics

    NASA Astrophysics Data System (ADS)

    Clementi, E.; Corongiu, G.; Detrich, J. H.; Kahnmohammadbaigi, H.; Chin, S.; Domingo, L.; Laaksonen, A.; Nguyen, N. L.

    1985-08-01

    Often very fundamental biochemical and biophysical problems defy simulations because of limitation in today's computers. We present and discuss a distributed system composed of two IBM-4341 and one IBM-4381, as front-end processors, and ten FPS-164 attached array processors. This parallel system-called LCAP-has presently a peak performance of about 120 MFlops; extensions to higher performance are discussed. Presently, the system applications use a modified version of VM/SP as the operating system: description of the modifications is given. Three applications programs have migrated from sequential to parallel; a molecular quantum mechanical, a Metropolis-Monte Carlo and a Molecular Dynamics program. Descriptions of the parallel codes are briefly outlined. As examples and tests of these applications we report on a study for proton tunneling in DNA base-pairs, very relevant to spontaneous mutations in genetics. As a second example, we present a Monte Carlo study of liquid water at room temperature where not only two- and three-body interactions are considered but-for the first time-also four-body interactions are included. Finally we briefly summarize a molecular dynamics study where two- and three-body interactions have been considered. These examples, and very positive performance comparison with today's supercomputers allow us to conclude that parallel computers and programming of the type we have considered, represent a pragmatic answer to many computer intensive problems.

  14. Photo-Triggered Click Chemistry for Biological Applications

    PubMed Central

    Herner, András; Lin, Qing

    2016-01-01

    In the last decade and a half, numerous bioorthogonal reactions have been developed with a goal to study biological processes in their native environment, i.e., in living cells and animals. Among them, the photo-triggered reactions offer several unique advantages including operational simplicity with the use of light rather than toxic metal catalysts and ligands, and exceptional spatiotemporal control through the application of an appropriate light source with pre-selected wavelength, light intensity and exposure time. While the photoinduced reactions have been studied extensively in materials research, e.g., on macromolecular surface, the adaptation of these reactions for chemical biology applications is still in its infancy. In this chapter, we review the recent efforts in the discovery and optimization the photo-triggered bioorthogonal reactions, with a focus on those that have shown broad utility in biological systems. We discuss in each cases the chemical and mechanistic background, the kinetics of the reactions and the biological applicability together with the limiting factors. PMID:27397964

  15. Laser-plasma accelerator and femtosecond photon sources-based ultrafast radiation chemistry and biophysics

    NASA Astrophysics Data System (ADS)

    Gauduel, Y. A.

    2017-02-01

    The initial distribution of energy deposition triggered by the interaction of ionizing radiations (far UV and X rays, electron, proton and accelerated ions) with molecular targets or integrated biological systems is often decisive for the spatio-temporal behavior of radiation effects that take place on several orders of magnitude. This contribution deals with an interdisciplinary approach that concerns cutting-edge advances on primary radiation events, considering the potentialities of innovating strategies based on ultrafast laser science, from femtosecond photon sources to laser-driven relativistic particles acceleration. Recent advances of powerful TW laser sources (~ 1019 Wcm‑2) and laser-plasma interactions providing ultrashort relativistic particle beams in the energy domain 2.5–150 MeV open exciting opportunities for the development of high-energy radiation femtochemistry (HERF). Early radiation damages being dependent on the survival probability of secondary electrons and radial distribution of short-lived radicals inside ionization clusters, a thorough knowledge of these processes involves the real-time probing of primary events in the temporal range 10‑14–10‑11 s. In the framework of a closed synergy between low-energy radiation femtochemistry (LERF) and the emerging domain of HERF, the paper focuses on early phenomena that occur in the prethermal regime of low-energy secondary electrons, considering very short-lived quantum effects in aqueous environments. A high dose-rate delivered by femtosecond electron beam (~ 1011–1013 Gy s‑1) can be used to investigate early radiation processes in native ionization tracks, down to 10‑12 s and 10‑9 m. We explain how this breakthrough favours the innovating development of real-time nanodosimetry in biologically relevant environments and open new perspectives for spatio-temporal radiation biophysics. The emerging domain of HERF would provide guidance for understanding the specific bioeffects of

  16. TERA-MIR radiation: materials, generation, detection and applications III (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Pereira, Mauro F.

    2016-10-01

    This talk summarizes the achievements of COST ACTION MP1204 during the last four years. [M.F. Pereira, Opt Quant Electron 47, 815-820 (2015).]. TERA-MIR main objectives are to advance novel materials, concepts and device designs for generating and detecting THz and Mid Infrared radiation using semiconductor, superconductor, metamaterials and lasers and to beneficially exploit their common aspects within a synergetic approach. We used the unique networking and capacity-building capabilities provided by the COST framework to unify these two spectral domains from their common aspects of sources, detectors, materials and applications. We created a platform to investigate interdisciplinary topics in Physics, Electrical Engineering and Technology, Applied Chemistry, Materials Sciences and Biology and Radio Astronomy. The main emphasis has been on new fundamental material properties, concepts and device designs that are likely to open the way to new products or to the exploitation of new technologies in the fields of sensing, healthcare, biology, and industrial applications. End users are: research centres, academic, well-established and start-up Companies and hospitals. Results are presented along our main lines of research: Intersubband materials and devices with applications to fingerprint spectroscopy; Metamaterials, photonic crystals and new functionalities; Nonlinearities and interaction of radiation with matter including biomaterials; Generation and Detection based on Nitrides and Bismides. The talk is closed by indicating the future direction of the network that will remain active beyond the funding period and our expectations for future joint research.

  17. Radiation Driven Wind Solutions and Applications

    NASA Astrophysics Data System (ADS)

    Curé, M.

    2016-11-01

    The standard modified-CAK equation of motion is a non-linear differential equation that possesses many singular points and therefore many solutions. Apart from the standard solution, we have found three other physical solutions: i) when the rotational velocity is higher than 3/4 of the critical rotational speed; ii) when there is a high ionization change throughout the wind; and iii) when the k line force parameter is very high (k is the fraction of the total stellar flux which would be blocked in the photosphere if all lines were optically thick). We also show some applications of these solutions, e.g., the wind of a B[e] supergiant, the oblate wind of a Be star, and the winds of BA supergiants. Furthermore, we calculate synthetic spectra with FASTWIND, where we have used our new hydrodynamical solutions as input to the code.

  18. Radiation processing applications in the Czechoslovak water treatment technologies

    NASA Astrophysics Data System (ADS)

    Vacek, K.; Pastuszek, F.; Sedláček, M.

    The regeneration of biologically clogged water wells by radiation proved to be a successful and economically beneficial process among other promising applications of ionizing radiation in the water supply technology. The application conditions and experience are mentioned. The potential pathogenic Mycobacteria occuring in the warm washing and bathing water are resistant against usual chlorine and ozone concentrations. The radiation sensitivity of Mycobacteria allowed to suggest a device for their destroying by radiation. Some toxic substances in the underground water can be efficiently degraded by gamma radiation directly in the wells drilled as a hydraulic barrier surrounding the contaminated land area. Substantial decrease of CN - concentration and C.O.D. value was observed in water pumped from such well equipped with cobalt sources and charcoal. The removing of pathogenic contamination remains to be the main goal of radiation processing in the water purification technologies. The decrease of liquid sludge specific filter resistance and sedimentation acceleration by irradiation have a minor technological importance. The hygienization of sludge cake from the mechanical belt filter press by electron beam appears to be the optimum application in the Czechoslovak conditions. The potatoes and barley crop yields from experimental plots treated with sludge were higher in comparison with using the manure. Biological sludge from the municipal and food industry water purification plants contains nutritive components. The proper hygienization is a necessary condition for using them as a livestock feed supplement. Feeding experiments with broilers and pigs confirmed the possibility of partial (e.g. 50%) replacement of soya-, bone- or fish flour in feed mixtures by dried sludge hygienized either by heat or by the irradiation.

  19. The Radiative Decay of Green and Red Photoluminescent Phosphors: An Undergraduate Kinetics Experiment for Materials Chemistry

    ERIC Educational Resources Information Center

    Esposti, C. Degli; Bizzocchi, L.

    2008-01-01

    This article describes a laboratory experiment that allows the students to investigate the radiative properties of the green and red emitting phosphors that are employed in commercial fluorescent lamps. Making use of a spectrofluorometer, students first record the emission spectrum of a fluorescent lamp under normal operating conditions, and then…

  20. Both host-plant phylogeny and chemistry have shaped the African seed-beetle radiation.

    PubMed

    Kergoat, Gaël J; Delobel, Alex; Fédière, Gilles; Rü, Bruno Le; Silvain, Jean-François

    2005-06-01

    For the last 40 years, many authors have attempted to characterize the main patterns of plant-insect evolutionary interactions and understand their causes. In the present work on African seed-beetles (Coleoptera: Bruchidae), we have performed a 10-year field work to sample seeds of more than 300 species of potential host-plants (from the family Fabaceae), to obtain bruchids by rearing. This seed sampling in the field was followed by the monitoring of adult emergences which gave us the opportunity to identify host-plant use accurately. Then, by using molecular phylogenetics (on a combined data set of four genes), we have investigated the relationships between host-plant preferences and insect phylogeny. Our objectives were to investigate the level of taxonomic conservatism in host-plant fidelity and host-plant chemistry. Our results indicate that phylogenetically related insects are associated with phylogenetically related host-plants but the phylogeny of the latter cannot alone explain the observed patterns. Major host shifts from Papilionoideae to Mimosoideae subfamilies have happened twice independently suggesting that feeding specialization on a given host-plant group is not always a dead end in seed-beetles. If host-plant taxonomy and chemistry in legumes generally provide consistent data, it appears that the nature of the seed secondary compounds may be the major factor driving the diversification of a large clade specializing on the subfamily Mimosoideae in which host-plant taxonomy is not consistent with chemical similarity.

  1. Simulating chemistry-aerosol-cloud-radiation-climate feedbacks over the continental U.S. using the online-coupled Weather Research Forecasting Model with chemistry (WRF/Chem)

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Wen, X.-Y.; Jang, C. J.

    2010-09-01

    The chemistry-aerosol-cloud-radiation-climate feedbacks are simulated using WRF/Chem over the continental U.S. in January and July 2001. Aerosols can reduce incoming solar radiation by up to -9% in January and -16% in July and 2-m temperatures by up to 0.16 °C in January and 0.37 °C in July over most of the continental U.S. The NO 2 photolysis rates decrease in July by up to -8% over the central and eastern U.S. where aerosol concentrations are high but increase by up to 7% over the western U.S. in July and up to 13% over the entire domain in January. Planetary boundary layer (PBL) height reduces by up to -23% in January and -24% in July. Temperatures and wind speeds in July in big cities such as Atlanta and New York City reduce at/near surface but increase at higher altitudes. The changes in PBL height, temperatures, and wind speed indicate a more stable atmospheric stability of the PBL and further exacerbate air pollution over areas where air pollution is already severe. Aerosols can increase cloud optical depths in big cities in July, and can lead to 500-5000 cm -3 cloud condensation nuclei (CCN) at a supersaturation of 1% over most land areas and 10-500 cm -3 CCN over ocean in both months with higher values over most areas in July than in January, particularly in the eastern U.S. The total column cloud droplet number concentrations are up to 4.9 × 10 6 cm -2 in January and up to 11.8 × 10 6 cm -2 in July, with higher values over regions with high CCN concentrations and sufficient cloud coverage. Aerosols can reduce daily precipitation by up to 1.1 mm day -1 in January and 19.4 mm day -1 in July thus the wet removal rates over most of the land areas due to the formation of small CCNs, but they can increase precipitation over regions with the formation of large/giant CCN. These results indicate potential importance of the aerosol feedbacks and an urgent need for their accurate representations in current atmospheric models to reduce uncertainties associated

  2. Chemistry and applications of flavylium compounds: a handful of colours.

    PubMed

    Pina, Fernando; Melo, Maria J; Laia, César A T; Parola, A Jorge; Lima, João C

    2012-01-21

    Flavylium compounds are versatile molecules that comprise anthocyanins, the ubiquitous colorants used by Nature to confer colour to most flowers and fruits. They have found a wide range of applications in human technology, from the millenary colour paints described by the Roman architect Vitruvius, to their use as food additives, combining colour and antioxidant effects, and even as light absorbers in solar cells aiming at a greener solar energy conversion. Their rich complexity derives in part from their ability to switch between a variety of species (flavylium cations, neutral quinoidal bases, hemiketals and chalcones, and negatively charged phenolates) by means of external stimuli, such as pH, temperature and light. This critical review describes (i) the historical advancements in the understanding of the equilibria of their chemical reaction networks; (ii) their thermodynamics and kinetics; (iii) the mechanisms underlying their colour development, such as co-pigmentation and host-guest interactions; (iv) the photophysics and photochemistry that lead to photochromism; and (v) applications in solar cells, models for optical memories, photochromic soft materials such as ionic liquids and gels, and their properties in solid state materials (274 references).

  3. Application of ultra high pressure (UHP) in starch chemistry.

    PubMed

    Kim, Hyun-Seok; Kim, Byung-Yong; Baik, Moo-Yeol

    2012-01-01

    Ultra high pressure (UHP) processing is an attractive non-thermal technique for food treatment and preservation at room temperature, with the potential to achieve interesting functional effects. The majority of UHP process applications in food systems have focused on shelf-life extension associated with non-thermal sterilization and a reduction or increase in enzymatic activity. Only a few studies have investigated modifications of structural characteristics and/or protein functionalities. Despite the rapid expansion of UHP applications in food systems, limited information is available on the effects of UHP on the structural and physicochemical properties of starch and/or its chemical derivatives included in most processed foods as major ingredients or minor additives. Starch and its chemical derivatives are responsible for textural and physical properties of food systems, impacting their end-use quality and/or shelf-life. This article reviews UHP processes for native (unmodified) starch granules and their effects on the physicochemical properties of UHP-treated starch. Furthermore, functional roles of UHP in acid-hydrolysis, hydroxypropylation, acetylation, and cross-linking reactions of starch granules, as well as the physicochemical properties of UHP-assisted starch chemical derivatives, are discussed.

  4. Lipidomics applications for discovering biomarkers of diseases in clinical chemistry.

    PubMed

    Zhao, Ying-Yong; Cheng, Xian-long; Lin, Rui-Chao

    2014-01-01

    Lipids are the fundamental components of biological membranes as well as the metabolites of organisms. Lipids play diverse and important roles in biologicals. The lipid imbalance is closely associated with numerous human lifestyle-related diseases, such as atherosclerosis, obesity, diabetes, and Alzheimer's disease. Lipidomics or lipid profiling is a system-based study of all lipids aiming at comprehensive analysis of lipids in the biological system. Lipidomics has been accepted as a lipid-related research tool in lipid biochemistry, clinical biomarker discovery, disease diagnosis, and in understanding disease pathology. Lipidomics will not only provide insights into the specific functions of lipid species in health and disease, but will also identify potential biomarkers for establishing preventive or therapeutic programs for human diseases. This review presents an overview of lipidomics followed by in-depth discussion of its application to the study of human diseases, including extraction methods of lipids, analytical technologies, data analysis, and clinical research in cancer, neuropsychiatric disease, cardiovascular disease, kidney disease, and respiratory disease. We describe the current status of the identification of metabolic biomarkers in different diseases. We also discuss the lipidomics for the future perspectives and their potential problems. The application of lipidomics in clinical studies may provide new insights into lipid profiling and pathophysiological mechanisms.

  5. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Astrophysics Data System (ADS)

    Stevenson, D. S.; Young, P. J.; Naik, V.; Lamarque, J.-F.; Shindell, D. T.; Voulgarakis, A.; Skeie, R. B.; Dalsoren, S. B.; Myhre, G.; Berntsen, T. K.; Folberth, G. A.; Rumbold, S. T.; Collins, W. J.; MacKenzie, I. A.; Doherty, R. M.; Zeng, G.; van Noije, T. P. C.; Strunk, A.; Bergmann, D.; Cameron-Smith, P.; Plummer, D. A.; Strode, S. A.; Horowitz, L.; Lee, Y. H.; Szopa, S.; Sudo, K.; Nagashima, T.; Josse, B.; Cionni, I.; Righi, M.; Eyring, V.; Conley, A.; Bowman, K. W.; Wild, O.; Archibald, A.

    2013-03-01

    Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m-2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12%), nitrogen oxides (31 ± 9%), carbon monoxide (15 ± 3%) and non-methane volatile organic compounds (9 ± 2%); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m-2 DU-1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m-2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the

  6. Tropospheric Ozone Changes, Radiative Forcing and Attribution to Emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Technical Reports Server (NTRS)

    Stevenson, D.S.; Young, P.J.; Naik, V.; Lamarque, J.-F.; Shindell, D. T.; Voulgarakis, A.; Skeie, R. B.; Dalsoren, S. B.; Myhre, G.; Berntsen, T. K.; Folberth, G. A.; Rumbold, S. T.; Collins, W. J.; MacKenzie, I. A.; Doherty, R. M.; Zeng, G.; vanNoije, T. P. C.; Strunk, A.; Bergmann, D.; Cameron-Smith, P.; Plummer, D. A.; Strode, S. A.; Horowitz, L.; Lee, Y. H.; Szopa, S.; Sudo, K.; Nagashima, T.; Josse, B.; Cionni, I.; Righi, M.; Eyring, V.; Conley, A.; Bowman, K. W.; Wild, O.; Archibald, A.

    2013-01-01

    Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m-2. The model range of pre-industrial to present-day changes in O3 produces a spread (+/-1 standard deviation) in RFs of +/-17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of +/-10 percent. Applying two different tropopause definitions gives differences in RFs of +/-3 percent. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of +/-30 percent for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44+/-12 percent), nitrogen oxides (31 +/- 9 percent), carbon monoxide (15 +/- 3 percent) and non-methane volatile organic compounds (9 +/- 2 percent); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m(-2) DU(-1), a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m(-2); relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some

  7. Introducing chemical biology applications to introductory organic chemistry students using series of weekly assignments.

    PubMed

    Kanin, Maralee R; Pontrello, Jason K

    2016-01-01

    Calls to bring interdisciplinary content and examples into introductory science courses have increased, yet strategies that involve course restructuring often suffer from the need for a significant faculty commitment to motivate change. Minimizing the need for dramatic course reorganization, the structure, reactivity, and chemical biology applications of classes of biological monomers and polymers have been integrated into introductory organic chemistry courses through three series of semester-long weekly assignments that explored (a) Carbohydrates and Oligosaccharides, (b) Amino Acids, Peptides, and Proteins, and (c) Nucleosides, Nucleotides, and Nucleic Acids. Comparisons of unannounced pre- and post tests revealed improved understanding of a reaction introduced in the assignments, and course examinations evaluated cumulative assignment topics. Course surveys revealed that demonstrating biologically relevant applications consistently throughout the semesters enhanced student interest in the connection between basic organic chemistry content and its application to new and unfamiliar bio-related examples. Covering basic material related to these classes of molecules outside of the classroom opened lecture time to allow the instructor to further build on information developed through the weekly assignments, teaching advanced topics and applications typically not covered in an introductory organic chemistry lecture course. Assignments were implemented as homework, either with or without accompanying discussion, in both laboratory and lecture organic courses within the context of the existing course structures.

  8. Application of the organic on water reactions to prebiotic chemistry

    NASA Astrophysics Data System (ADS)

    Kolb, Vera M.

    2012-10-01

    The old view that prebiotic reactions in water are hampered by the low solubility of the organic compounds in water is now being revised due to the discoveries of the reactions "on water". These reactions occur in the heterogeneous system comprising of the organic compounds and water. Unexpectedly, such reactions are extremely efficient; they often give quantitative yields, and are accelerated in the presence of water as compared to the organic solvents. These "on water" reactions are not the same as the "in water" reactions, which occur in solution, and are thus homogenous. Examples of the "on water" reactions include Diels-Alder, Claisen, Passerini and Ugi reactions, among many others. Some of these reactions are multicomponent, but give a single product. We survey a selected number of the "on water" reactions, which have a potential prebiotic applications.

  9. Testing the Physics and Chemistry of Radiation Driven Cloud Evolution - [C II] Mapping of IC 59 and IC 63

    NASA Astrophysics Data System (ADS)

    Andersson, B.-G.

    The interaction of newly formed stars with their natal clouds give rise to a number of dynamical and chemical effects, forming H II regions, injecting energy in the surrounding ISM and, potentially giving ride to triggered star formation. When an expanding H II region encounters density enhancements, Bright Rimmed Clouds (BRC) are formed, containing photo-dissociation regions (PDR). These provide valuable laboratories of radiation driven dynamics both for cloud dynamics and the physical and chemical evolution of the gas and dust. We propose to map the near-by pair of BRCs IC59 and IC 63, in the [C II] line, a well-known PDR tracer, with the upGREAT LFA array. These observations will complement a significant amount of existing data tracing the molecular gas and dust in the clouds. The parallel CO (J=11-10) data from the L1 channel will provide important information about the dense warm molecular gas to be compared e.g. to existing low-J CO transitions. Although at similar distance from the illuminating star gamma Cas, the two nebulae show dramatic differences in their structure. Because of their relative vicinity ( 190pc), the clouds provide a unique environment to acquire high spatial resolution observation of BRC and PDRs. Because of the high spectral resolution of upGREAT, our observations will provide detailed information about gas flows and turbulent motions, providing important constraints and test for models of radiation driven cloud evolution and the chemistry and physics of PDRs.

  10. Towards a Radiation Hardened Fluxgate Magnetometer for Space Physics Applications

    NASA Astrophysics Data System (ADS)

    Miles, David M.

    Space-based measurements of the Earth's magnetic field are required to understand the plasma processes of the solar-terrestrial connection which energize the Van Allen radiation belts and cause space weather. This thesis describes a fluxgate magnetometer payload developed for the proposed Canadian Space Agencys Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) mission. The instrument can resolve 8 pT on a 65,000 nT field at 900 samples per second with a magnetic noise of less than 10 pT per square-root Hertz at 1 Hertz. The design can be manufactured from radiation tolerant (100 krad) space grade parts. A novel combination of analog temperature compensation and digital feedback simplifies and miniaturises the instrument while improving the measurement bandwidth and resolution. The prototype instrument was successfully validated at the Natural Resources Canada Geomagnetics Laboratory, and is being considered for future ground, satellite and sounding rocket applications.

  11. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields, volume 2

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1991-01-01

    A technique was developed for predicting the character and magnitude of the shock wave precursor ahead of an entry vehicle and the effect of this precursor on the vehicle flow field was ascertained. A computational method and program were developed to properly model this precursor. Expressions were developed for the mass production rates of each species due to photodissociation and photoionization reactions. Also, consideration was given to the absorption and emission of radiation and how it affects the energy in each of the energy modes of both the atomic and diatomic species. A series of parametric studies were conducted covering a range of entry conditions in order to predict the effects of the precursor on the shock layer and the radiative heat transfer to the body.

  12. Effect of coolant chemistry on PWR radiation transport processes. Progress report on reactor loop studies

    SciTech Connect

    Brown, D.J.; Flynn, G.; Haynes, J.W.; Kitt, G.P.; Large, N.R.; Lawson, D.; Mead, A.P.; Nichols, J.L.; Woodwark, D.R.

    1986-05-01

    The effect of various PWR-type coolant chemistry regimes on the behavior of corrosion products has been studied in the DIDO Water Loop at Harwell. There are strong indications that the in-core deposition behavior of corrosion product species is not fully accounted for by the solubility model based on nickel ferrite; boric acid plays a role apart from its influence on pH, and corrosion products are adsorbed to some extent in the zirconium oxide film on the fuel cladding. In DWL, soluble species appear to be dominant in deposition processes. A most important factor governing deposition behavior is surface condition; the influence of weld regions and the effect of varying pretreatment conditions have both been demonstrated. 13 figs.

  13. Application of symmetry operation measures in structural inorganic chemistry.

    PubMed

    Echeverría, Jorge; Alvarez, Santiago

    2008-12-01

    This paper presents an application of the recently proposed symmetry operation measures to the determination of the effective symmetry point group of coordination polyhedra in inorganic solids. Several structure types based on octahedra are found to present distinct distortion patterns each, not strictly attached to the crystallographic site symmetry. These include the (NH4)2[CuCl4], CdI2 (brucite), FeS2 (pyrite), TiO2 (rutile), CaCl2, GdFeO3, PbTiO3,LiNbO3, BiI3, CrCl3, Al2O3, and NiWO4 structures. It is shown that a similar analysis can be applied to the Bailar and tetragonal Jahn-Teller distortions of molecular transition metal complexes, as well as to solids based on tetrahedra, such as the ZnCl2, FeS, BeCl2, SiS2, and KFeS2 structure types.

  14. Radiation chemistry in the reprocessing and recycling of spent nuclear fuels

    SciTech Connect

    Bruce J. Mincher

    2015-04-01

    The interaction of ionizing radiation with solvent extraction solutions results in the ionization, excitation, and decay to neutral radicals of mainly diluent molecules. These produced reactive species diffuse into the bulk solution to react with solvent extraction ligands. Ligand reactions often result in deleterious effects such as loss in ligand concentration or the production of decomposition products that may also be complexing agents. This often interferes with desired separations. The common radiolysis reactions and their potential effects on solvent extraction are reviewed here.

  15. Radiative shocks and nonequilibrium chemistry in the early universe - Galaxy and primordial star formation

    NASA Technical Reports Server (NTRS)

    Shapiro, Paul R.; Kang, Hyesung

    1990-01-01

    The nonequilibrium radiative cooling, recombination, and molecule formation behind steady-state shock waves in primordial composition gas is studied. The hydrodynamical conservation equations are solved as well as equations for nonequilibrium ionization, recombination, and molecule formation and the equation of radiative transfer. The shocked gas is found to cool faster than it can recombine; as a result it is able to form an H2 concentration as high as 0.001 or higher via the formation of H(-) and H2(+) intermediaries due to the enhanced nonequilibrium ionization at 10,000 K. With such an H2 concentration, the gas cools by rotational-vibrational line excitation of H2 molecules to well below the canonical final temperature of 10,000 K for a molecule-free gas without metals. It is shown that, as the level of external ionizing and dissociating radiation flux is increased, the formation of and cooling by H2 molecules can be inhibited and delayed.

  16. Production of superparamagnetic nanobiocatalysts for green chemistry applications.

    PubMed

    Gasser, Christoph A; Ammann, Erik M; Schäffer, Andreas; Shahgaldian, Patrick; Corvini, Philippe F-X

    2016-08-01

    Immobilization of enzymes on solid supports is a convenient method for increasing enzymatic stability and enabling enzyme reuse. In the present work, a sorption-assisted surface conjugation method was developed and optimized to immobilize enzymes on the surface of superparamagnetic nanoparticles. An oxidative enzyme, i.e., laccase from Trametes versicolor was used as model enzyme. The immobilization method consists of the production of superparamagnetic nanoparticles by co-precipitation of FeCl2 and FeCl3. Subsequently, the particle surface is modified with an organosilane containing an amino group. Next, the enzymes are adsorbed on the particle surface before a cross-linking agent, i.e., glutaraldehyde is added which links the amino groups on the particle surface with the amino groups of the enzymes and leads to internal cross-linking of the enzymes as well. The method was optimized using response surface methodology regarding optimal enzyme and glutaraldehyde amounts, pH, and reaction times. Results allowed formulation of biocatalysts having high specific enzymatic activity and improved stability. The biocatalysts showed considerably higher stability compared with the dissolved enzymes over a pH range from 3 to 9 and in the presence of several chemical denaturants. To demonstrate the reusability of the immobilized enzymes, they were applied as catalysts for the production of a phenoxazinone dye. Virtually, 100 % of the precursor was transformed to the dye in each of the ten conducted reaction cycles while on average 84.5 % of the enzymatic activity present at the beginning of a reaction cycle was retained after each cycle highlighting the considerable potential of superparamagnetic biocatalysts for application in industrial processes.

  17. Evolution of ozone, particulates, and aerosol direct radiative forcing in the vicinity of Houston using a fully coupled meteorology-chemistry-aerosol model

    NASA Astrophysics Data System (ADS)

    Fast, Jerome D.; Gustafson, William I.; Easter, Richard C.; Zaveri, Rahul A.; Barnard, James C.; Chapman, Elaine G.; Grell, Georg A.; Peckham, Steven E.

    2006-11-01

    A new fully coupled meteorology-chemistry-aerosol model is used to simulate the urban- to regional-scale variations in trace gases, particulates, and aerosol direct radiative forcing in the vicinity of Houston over a 5 day summer period. Model performance is evaluated using a wide range of meteorological, chemistry, and particulate measurements obtained during the 2000 Texas Air Quality Study. The predicted trace gas and particulate distributions were qualitatively similar to the surface and aircraft measurements with considerable spatial variations resulting from urban, power plant, and industrial sources of primary pollutants. Sulfate, organic carbon, and other inorganics were the largest constituents of the predicted particulates. The predicted shortwave radiation was 30 to 40 W m-2 closer to the observations when the aerosol optical properties were incorporated into the shortwave radiation scheme; however, the predicted hourly aerosol radiative forcing was still underestimated by 10 to 50 W m-2. The predicted aerosol radiative forcing was larger over Houston and the industrial ship channel than over the rural areas, consistent with surface measurements. The differences between the observed and simulated aerosol radiative forcing resulted from transport errors, relative humidity errors in the upper convective boundary layer that affect aerosol water content, secondary organic aerosols that were not yet included in the model, and uncertainties in the primary particulate emission rates. The current model was run in a predictive mode and demonstrates the challenges of accurately simulating all of the meteorological, chemical, and aerosol parameters over urban to regional scales that can affect aerosol radiative forcing.

  18. Radiative Effect of Clouds on Tropospheric Chemistry in a Global Three-Dimensional Chemical Transport Model

    NASA Technical Reports Server (NTRS)

    Liu, Hongyu; Crawford, James H.; Pierce, Robert B.; Norris, Peter; Platnick, Steven E.; Chen, Gao; Logan, Jennifer A.; Yantosca, Robert M.; Evans, Mat J.; Kittaka, Chieko; Feng, Yan; Tie, Xuexi

    2006-01-01

    Clouds exert an important influence on tropospheric photochemistry through modification of solar radiation that determines photolysis frequencies (J-values). We assess the radiative effect of clouds on photolysis frequencies and key oxidants in the troposphere with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations from the Goddard Earth Observing System data assimilation system (GEOS DAS) at the NASA Global Modeling and Assimilation Office (GMAO). We focus on the year of 2001 with the GEOS-3 meteorological observations. Photolysis frequencies are calculated using the Fast-J radiative transfer algorithm. The GEOS-3 global cloud optical depth and cloud fraction are evaluated and generally consistent with the satellite retrieval products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP). Results using the linear assumption, which assumes linear scaling of cloud optical depth with cloud fraction in a grid box, show global mean OH concentrations generally increase by less than 6% because of the radiative effect of clouds. The OH distribution shows much larger changes (with maximum decrease of approx.20% near the surface), reflecting the opposite effects of enhanced (weakened) photochemistry above (below) clouds. The global mean photolysis frequencies for J[O1D] and J[NO2] in the troposphere change by less than 5% because of clouds; global mean O3 concentrations in the troposphere increase by less than 5%. This study shows tropical upper tropospheric O3 to be less sensitive to the radiative effect of clouds than previously reported (approx.5% versus approx.20-30%). These results emphasize that the dominant effect of clouds is to influence the vertical redistribution of the intensity of photochemical activity while global average effects remain modest, again contrasting with previous studies. Differing vertical distributions

  19. 25th anniversary article: progress in chemistry and applications of functional indigos for organic electronics.

    PubMed

    Głowacki, Eric Daniel; Voss, Gundula; Sariciftci, Niyazi Serdar

    2013-12-17

    Indigo and its derivatives are dyes and pigments with a long and distinguished history in organic chemistry. Recently, applications of this 'old' structure as a functional organic building block for organic electronics applications have renewed interest in these molecules and their remarkable chemical and physical properties. Natural-origin indigos have been processed in fully bio-compatible field effect transistors, operating with ambipolar mobilities up to 0.5 cm(2) /Vs and air-stability. The synthetic derivative isoindigo has emerged as one of the most successful building-blocks for semiconducting polymers for plastic solar cells with efficiencies > 5%. Another isomer of indigo, epindolidione, has also been shown to be one of the best reported organic transistor materials in terms of mobility (∼2 cm(2) /Vs) and stability. This progress report aims to review very recent applications of indigoids in organic electronics, but especially to logically bridge together the hereto independent research directions on indigo, isoindigo, and other materials inspired by historical dye chemistry: a field which was the root of the development of modern chemistry in the first place.

  20. Rectangular Microstrip Radiator for a Multielement Local Hyperthermia Applicator.

    NASA Astrophysics Data System (ADS)

    Underwood, Harold Roger

    1990-11-01

    Advances in printed circuit technology facilitate the design of thin, conformable, microstrip patch antenna arrays. Such multielement microwave antenna arrays can be advantageous for controlled heating of superficial malignancies during cancer therapy. This thesis reports a theoretical analysis and design verification of the rectangular microstrip radiator for a hyperthermia applicator. Applicability of a cavity model approach for predicting near field patterns of a probe fed microstrip patch radiating in a lossy homogeneous medium is analyzed throughout a step-by-step development based on electromagnetic principles. A modal expansion technique and length correction factor slightly improve this model. Limitations of the simplifying assumptions and approximations in this model are tested by comparing numerical results of a single patch radiating in water with the measured results from an electric field probe. The measurement probe is an encapsulated miniature dipole designed for microwave transparent nonperturbing electric field measurement in biomedical media. Results show that safe and efficient performance of a microstrip patch as a biomedical radiator can be enhanced by a thin superstrate cover layer. Linear array patterns indicate that amplitude and phase variations can compensate for mutual coupling effects to adjust beam width and smoothness necessary in controlled hyperthermia heating.

  1. Usage and applications of Semantic Web techniques and technologies to support chemistry research

    PubMed Central

    2014-01-01

    Background The drug discovery process is now highly dependent on the management, curation and integration of large amounts of potentially useful data. Semantics are necessary in order to interpret the information and derive knowledge. Advances in recent years have mitigated concerns that the lack of robust, usable tools has inhibited the adoption of methodologies based on semantics. Results This paper presents three examples of how Semantic Web techniques and technologies can be used in order to support chemistry research: a controlled vocabulary for quantities, units and symbols in physical chemistry; a controlled vocabulary for the classification and labelling of chemical substances and mixtures; and, a database of chemical identifiers. This paper also presents a Web-based service that uses the datasets in order to assist with the completion of risk assessment forms, along with a discussion of the legal implications and value-proposition for the use of such a service. Conclusions We have introduced the Semantic Web concepts, technologies, and methodologies that can be used to support chemistry research, and have demonstrated the application of those techniques in three areas very relevant to modern chemistry research, generating three new datasets that we offer as exemplars of an extensible portfolio of advanced data integration facilities. We have thereby established the importance of Semantic Web techniques and technologies for meeting Wild’s fourth “grand challenge”. PMID:24855494

  2. Modeling calcium sulfate chemistries with applications to Mars

    NASA Astrophysics Data System (ADS)

    Marion, G. M.; Catling, D. C.; Kargel, J. S.; Crowley, J. K.

    2016-11-01

    On Mars, evidence indicates widespread calcium sulfate minerals. Gypsum (CaSO4ṡ2H2O) seems to be the dominant calcium sulfate mineral in the north polar region of Mars. On the other hand, anhydrite (CaSO4) and bassanite (CaSO4ṡ0.5H2O) appear to be more common in large sedimentary deposits in the lower latitudes. The tropics are generally warmer and drier, and at least locally show evidence of acidic environments in the past. FREZCHEM is a thermodynamic modeling tool used for assessment of equilibrium involving high salinity solutions and salts, designed especially for low temperatures below 298 K (with one version adapted for temperatures up to 373 K), and we have used it to investigate many Earth, Mars, and other planetary science problems. Gypsum and anhydrite were included in earlier versions of FREZCHEM and our model Mars applications, but bassanite (the CaSO4 hemihydrate) has not previously been included. The objectives of this work are to (1) add bassanite to the FREZCHEM model, (2) examine the environments in which thermodynamic equilibrium precipitation of calcium sulfate minerals would be favored on Mars, and (3) use FREZCHEM to model situations where metastable equilibrium might be favored and promote the formation or persistence of one of these phases over the others in violation of an idealized equilibrium state. We added a bassanite equation based on high temperatures (343-373 K). A Mars simulation was based on a previously published Nasbnd Casbnd Mgsbnd Clsbnd SO4 system over the temperature range of 273 to 373 K. With declining temperatures, the first solid phase under equilibrium precipitation is anhydrite at 373 K, then gypsum forms at 319 K (46 °C), and epsomite (MgSO4ṡ7H2O) at 277 K. This sequence could reflect, for example, the precipitation sequence in a saturated solution that is slowly cooled in a deep, warm aquifer. Because FREZCHEM is based on thermodynamic equilibrium, a crude approach to problems involving metastable equilibria is

  3. Hydrothermal carbonization of biomass residuals: A comparative review of the chemistry, processes and applications of wet and dry pyrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper reviews chemistry, processes and application of hydrothermcally carbonized biomass wastes. Potential feedstock for the hydrothermal carbonization (HTC) includes variety of the non-traditional renewable wet agricultural and municipal waste streams. Pyrolysis and HTC show a comparable calor...

  4. Walking in the woods with quantum chemistry--applications of quantum chemical calculations in natural products research.

    PubMed

    Tantillo, Dean J

    2013-08-01

    This Highlight describes applications of quantum chemical calculations to problems in natural products chemistry, including the elucidation of natural product structures (distinguishing between constitutional isomers, distinguishing between diastereomers, and assigning absolute configuration) and determination of reasonable mechanisms for their formation.

  5. Solar Position Algorithm for Solar Radiation Applications (Revised)

    SciTech Connect

    Reda, I.; Andreas, A.

    2008-01-01

    This report is a step-by-step procedure for implementing an algorithm to calculate the solar zenith and azimuth angles in the period from the year -2000 to 6000, with uncertainties of ?0.0003/. It is written in a step-by-step format to simplify otherwise complicated steps, with a focus on the sun instead of the planets and stars in general. The algorithm is written in such a way to accommodate solar radiation applications.

  6. Recent applications of synchrotron VUV photoionization mass spectrometry: insight into combustion chemistry.

    PubMed

    Li, Yuyang; Qi, Fei

    2010-01-19

    Combustion is one of the earliest developed human technologies and remains our primary source of energy, yet it embodies a complex suite of physical and chemical processes that are inadequately understood. Combustion chemistry involves both chemical thermodynamics and chemical kinetics, and experimental advances mostly depend on the development of combustion diagnostics, which effectively serve as the foundation of theoretical progress. The major objective of combustion diagnostics is to provide comprehensive product identification and concentration information of a flame species, which can be used to develop kinetic models for the simulation of practical combustion. However, conventional combustion diagnostic methods face difficult challenges in distinguishing isomeric species, detecting reactive radicals, obtaining real-time measurements, and so forth. Therefore, for deeper insight into combustion chemistry, a diagnostic method with high detection sensitivity, isomeric selectivity, and radical detectability is required. In this Account, we report recent applications of synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) in various areas of combustion chemistry research. The wide tunability of synchrotron photon energy can facilitate the selective identification of isomeric intermediates and the near-threshold detection of radicals (thus avoiding fragmentation interference). Moreover, the convenient combination of SVUV-PIMS with various laboratory-based combustion approaches demonstrates its universality in combustion studies. Recent experimental achievements have demonstrated the successful applications of this technique in premixed flames, pyrolysis in flow reactors, coflow diffusion flames, catalytic oxidation, plasma diagnostics, and analysis of polycyclic aromatic hydrocarbons (PAHs) and soot. More applications of SVUV-PIMS are expected in the near future, not only in combustion studies, but also in other research topics of chemistry

  7. Ionizing Radiation-Induced Responses: Where Free Radical Chemistry Meets Redox Biology and Medicine

    PubMed Central

    Hauer-Jensen, Martin

    2014-01-01

    Abstract The biological effects of ionizing radiation (IR) from environmental, medical, and man-made sources, as well as from space exploration are of broad health concern. During the last 40 years it has become evident that, in addition to short-lived free radical-mediated events initiated within microseconds of exposure and generally thought to dissipate within milliseconds, IR-induced production of reactive oxygen and nitrogen species as well as changes in redox signaling linked to disruption of metabolic processes persist long after radiation exposure. Furthermore, persistent IR-induced increases in the metabolic production of reactive oxygen and nitrogen species appear to significantly contribute to the delayed effects of IR exposure, including induction of adaptive responses at low doses as well as carcinogenesis, fibrosis, inflammation, genomic instability, and acceleration of the onset of degenerative tissue injury processes associated with aging. The ability to identify the specific metabolic mechanisms and dose–response relationships that contribute to adaptive responses as well as persistent IR-induced injury processes holds great promise for identifying novel strategies to mitigate the deleterious effects of IR exposure as well as for gathering mechanistic information critical for risk assessment. This Forum contains original and review articles authored by experts in the field of radiobiology focusing on novel mechanisms involving redox biology and metabolism that significantly contribute to the persistent biological effects seen following IR exposure. Antioxid. Redox Signal. 20, 1407–1409. PMID:24354361

  8. A Radiation Chemistry Code Based on the Green's Function of the Diffusion Equation

    NASA Technical Reports Server (NTRS)

    Plante, Ianik; Wu, Honglu

    2014-01-01

    Stochastic radiation track structure codes are of great interest for space radiation studies and hadron therapy in medicine. These codes are used for a many purposes, notably for microdosimetry and DNA damage studies. In the last two decades, they were also used with the Independent Reaction Times (IRT) method in the simulation of chemical reactions, to calculate the yield of various radiolytic species produced during the radiolysis of water and in chemical dosimeters. Recently, we have developed a Green's function based code to simulate reversible chemical reactions with an intermediate state, which yielded results in excellent agreement with those obtained by using the IRT method. This code was also used to simulate and the interaction of particles with membrane receptors. We are in the process of including this program for use with the Monte-Carlo track structure code Relativistic Ion Tracks (RITRACKS). This recent addition should greatly expand the capabilities of RITRACKS, notably to simulate DNA damage by both the direct and indirect effect.

  9. Pulsed electron accelerator for radiation technologies in the enviromental applications

    NASA Astrophysics Data System (ADS)

    Korenev, Sergey

    1997-05-01

    The project of pulsed electron accelerator for radiation technologies in the environmental applications is considered. An accelerator consists of high voltage generator with vacuum insulation and vacuum diode with plasma cathode on the basis discharge on the surface of dielectric of large dimensions. The main parameters of electron accelerators are following: kinetic energy 0.2 - 2.0 MeV, electron beam current 1 - 30 kA and pulse duration 1- 5 microseconds. The main applications of accelerator for decomposition of wastewaters are considered.

  10. Combinatorial computational chemistry approach for materials design: applications in deNOx catalysis, Fischer-Tropsch synthesis, lanthanoid complex, and lithium ion secondary battery.

    PubMed

    Koyama, Michihisa; Tsuboi, Hideyuki; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Del Carpio, Carlos A; Miyamoto, Akira

    2007-02-01

    Computational chemistry can provide fundamental knowledge regarding various aspects of materials. While its impact in scientific research is greatly increasing, its contributions to industrially important issues are far from satisfactory. In order to realize industrial innovation by computational chemistry, a new concept "combinatorial computational chemistry" has been proposed by introducing the concept of combinatorial chemistry to computational chemistry. This combinatorial computational chemistry approach enables theoretical high-throughput screening for materials design. In this manuscript, we review the successful applications of combinatorial computational chemistry to deNO(x) catalysts, Fischer-Tropsch catalysts, lanthanoid complex catalysts, and cathodes of the lithium ion secondary battery.

  11. Nanoparticles-chemistry, new synthetic approaches, gas phase clustering and novel applications

    NASA Astrophysics Data System (ADS)

    Sreekumaran Nair, A.; Subramaniam, Chandramouli; Rosemary, M. J.; Tom, Renjis T.; Rajeev Kumar, V. R.; Jeba Singh, D. M. David; Cyriac, Jobin; Jain, Prashant; Kalesh, K. A.; Bhattacharya, Shreya; Pradeep, T.

    2005-10-01

    In this paper, an overview of the synthesis, chemistry and applications of nanosystems carried out in our laboratory is presented. The discussion is divided into four sections, namely (a) chemistry of nanoparticles, (b) development of new synthetic approaches, (c) gas phase clusters and (d) device structures and applications. In `chemistry of nanoparticles' we describe a novel reaction between nanoparticles of Ag and Au with halocarbons. The reactions lead to the formation of various carbonaceous materials and metal halides. In `development of new synthetic approaches' our one-pot methodologies for the synthesis of core-shell nanosystems of Au, Ag and Cu protected with TiO_2 and ZrO_2 as well as various polymers are discussed. Some results on the interaction of nanoparticles with biomolecules are also detailed in this section. The third section covers the formation of gas phase aggregates/clusters of thiol-protected sub-nanoparticles. Laser desorption of H_2MoO_4, H_2WO_4, MoS_2, and WS_2 giving novel clusters is discussed. The fourth section deals with the development of simple devices and technologies using nanomaterials described above.

  12. USSR Report, Chemistry.

    DTIC Science & Technology

    2007-11-02

    Industry, Coal Gasification , Electrochemistry, Inorganic Compounds, Nitrogen Compounds, Organophosphorus Compounds, Petroleum Processing Technology, Pharmacology and Toxicology, Polymers and Polymerization and, Radiation Chemistry.

  13. Applications of quantum chemistry to gas and solid phase reaction kinetics

    NASA Astrophysics Data System (ADS)

    Senosiain, Juan Pablo

    Chemical kinetics has nourished from the achievements of computational quantum chemistry as perhaps no other field. This thesis illustrates the application of first-principles calculations to elucidate complex reaction mechanisms, and to quantitatively simulate reaction rates. The work embodied in this dissertation encompasses several projects with very diverse applications. In some cases, quantum chemistry calculations have been used for predicting reaction rates, while in others they are used in a semi-qualitative manner to elucidate complex reaction mechanisms. The first two chapters of this dissertation explain some key theoretical concepts of quantum chemistry and chemical kinetics. They are not intended to be exhaustive or detailed, but rather to illustrate general principles that are applied in the subsequent chapters. Chapter three reviews the disperse literature on the statistical treatment of internal rotors and provides a comparison of commonly used approximations. Chapters four through six cover three areas of special interest to gas-phase kinetics: bond dissociation energies, transition state theory and unimolecular reactions, with particular emphasis on combustion and atmospheric chemistry applications. A critical assessment of reaction barriers and bond dissociation energies calculated with several ab initio methods in common use is provided in chapters four and five, respectively. Chapters seven and eight illustrate how quantum chemistry can be used to decipher complex reaction mechanisms, with applications to current and future problems in semiconductor processing. The former studies the mechanisms of boron diffusion through thin gate oxide layers in metal oxide field effect transistors (MOSFETs). The latter investigates the details of atomic layer deposition (ALD) reactions on germanium and silicon-germanium alloys. Both of these studies are motivated by the miniaturization trend in gate oxide layers in MOSFET devices. As the device feature size

  14. Technetium chemistry

    SciTech Connect

    Burns, C.; Bryan, J.; Cotton, F.; Ott, K.; Kubas, G.; Haefner, S.; Barrera, J.; Hall, K.; Burrell, A.

    1996-04-01

    Technetium chemistry is a young and developing field. Despite the limited knowledge of its chemistry, technetium is the workhorse for nuclear medicine. Technetium is also a significant environmental concern because it is formed as a byproduct of nuclear weapons production and fission-power generators. Development of new technetium radio-pharmaceuticals and effective environmental control depends strongly upon knowledge of basic technetium chemistry. The authors performed research into the basic coordination and organometallic chemistry of technetium and used this knowledge to address nuclear medicine and environmental applications. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  15. Quantum chemistry calculations for molecules coupled to reservoirs: Formalism, implementation, and application to benzenedithiol

    NASA Astrophysics Data System (ADS)

    Arnold, A.; Weigend, F.; Evers, F.

    2007-05-01

    Modern quantum chemistry calculations are usually implemented for isolated systems—big molecules or atom clusters; total energy and particle number are fixed. However, in many situations, like quantum transport calculations or molecules in a electrochemical environment, the molecule can exchange particles (and energy) with a reservoir. Calculations for such cases require to switch from the canonical to a grand canonical description, where one fixes the chemical potential rather than particle number. To achieve this goal, the authors propose an implementation in standard quantum chemistry packages. An application to the nonlinear charge transport through 1,4-benzenedithiol will be presented. They explain the leading finite bias effect on the transmission as a consequence of a nonequilibrium Stark effect and discuss the relation to earlier work.

  16. The application of click chemistry in the synthesis of agents with anticancer activity

    PubMed Central

    Ma, Nan; Wang, Ying; Zhao, Bing-Xin; Ye, Wen-Cai; Jiang, Sheng

    2015-01-01

    The copper(I)-catalyzed 1,3-dipolar cycloaddition between alkynes and azides (click chemistry) to form 1,2,3-triazoles is the most popular reaction due to its reliability, specificity, and biocompatibility. This reaction has the potential to shorten procedures, and render more efficient lead identification and optimization procedures in medicinal chemistry, which is a powerful modular synthetic approach toward the assembly of new molecular entities and has been applied in anticancer drugs discovery increasingly. The present review focuses mainly on the applications of this reaction in the field of synthesis of agents with anticancer activity, which are divided into four groups: topoisomerase II inhibitors, histone deacetylase inhibitors, protein tyrosine kinase inhibitors, and antimicrotubule agents. PMID:25792812

  17. The application of click chemistry in the synthesis of agents with anticancer activity.

    PubMed

    Ma, Nan; Wang, Ying; Zhao, Bing-Xin; Ye, Wen-Cai; Jiang, Sheng

    2015-01-01

    The copper(I)-catalyzed 1,3-dipolar cycloaddition between alkynes and azides (click chemistry) to form 1,2,3-triazoles is the most popular reaction due to its reliability, specificity, and biocompatibility. This reaction has the potential to shorten procedures, and render more efficient lead identification and optimization procedures in medicinal chemistry, which is a powerful modular synthetic approach toward the assembly of new molecular entities and has been applied in anticancer drugs discovery increasingly. The present review focuses mainly on the applications of this reaction in the field of synthesis of agents with anticancer activity, which are divided into four groups: topoisomerase II inhibitors, histone deacetylase inhibitors, protein tyrosine kinase inhibitors, and antimicrotubule agents.

  18. Chemistry and applications of organotin(IV) complexes of Schiff bases.

    PubMed

    Nath, Mala; Saini, Pramendra K

    2011-07-21

    Schiff bases are the most widely used versatile ligands, able to coordinate many elements and to stabilize them in various oxidation states. Recently, this class of compounds has been employed as models for biological systems, and in control of stereochemistry in six-coordinate transition metal complexes. Recently, the chemistry of organotin(IV) complexes of Schiff bases has also stemmed from their antitumour, antimicrobial, antinematicidal, anti-insecticidal and anti-inflammatory activities. Furthermore, organotin(IV) complexes of Schiff bases present a wide variety of interesting structural possibilities. Both aliphatic and aromatic Schiff bases in their neutral and deprotonated forms have been used to yield adducts and chelates with variable stoichiometry and different modes of coordination. This critical review (>155 references) focuses upon the chemistry and biological applications of organotin(IV) complexes of Schiff bases reported in the past 15 years. Thermal behavior of these complexes is also discussed.

  19. Theory and measurement of emittance properties for radiation thermometry applications.

    NASA Technical Reports Server (NTRS)

    Dewitt, D. P.; Hernicz, R. S.

    1972-01-01

    Some basic concepts of radiation physics are briefly reviewed to provide an introduction to the radiative properties - including emittance, reflectance, absorptance, and transmittance - their definitions, interrelations, theory and methods of measurement. Analyzed data showing typical characteristics of temperature and wavelength dependence, surface effects and environmental influences on the radiation properties of selected classes of materials are presented. Emphasis is placed on those emittance properties of particular interest to conventional radiation thermometry applications, but sufficient generality on all properties is presented to be useful for new or unusual techniques where a more detailed understanding of the behavior of materials is desirable. Data sources are identified to assist the reader in locating property information. It is the intention of the paper to give the reader a background to become more fully aware of the pitfalls, limitations, but of course, advantages in the use of data from the literature. The paper is written in the form of an abbreviated review fully documenting the more important topics and concepts which can only be treated briefly.

  20. Annual Report: Hydrodynamics and Radiative Hydrodynamics with Astrophysical Applications

    SciTech Connect

    R. Paul Drake

    2005-12-01

    We report the ongoing work of our group in hydrodynamics and radiative hydrodynamics with astrophysical applications. During the period of the existing grant, we have carried out two types of experiments at the Omega laser. One set of experiments has studied radiatively collapsing shocks, obtaining high-quality scaling data using a backlit pinhole and obtaining the first (ever, anywhere) Thomson-scattering data from a radiative shock. Other experiments have studied the deeply nonlinear development of the Rayleigh-Taylor (RT) instability from complex initial conditions, obtaining the first (ever, anywhere) dual-axis radiographic data using backlit pinholes and ungated detectors. All these experiments have applications to astrophysics, discussed in the corresponding papers either in print or in preparation. We also have obtained preliminary radiographs of experimental targets using our x-ray source. The targets for the experiments have been assembled at Michigan, where we also prepare many of the simple components. The above activities, in addition to a variety of data analysis and design projects, provide good experience for graduate and undergraduates students. In the process of doing this research we have built a research group that uses such work to train junior scientists.

  1. A novel structure optical fiber radiation dosimeter for radiotherapy applications

    NASA Astrophysics Data System (ADS)

    Sun, Weimin; Qin, Zhuang; Ma, Yu; Zhao, Wenhui; Hu, Yaosheng; Zhang, Daxin; Chen, Ziyin; Lewis, Elfed

    2016-04-01

    An investigation into a novel in-vivo PMMA (polymethyl methacrylate) fiber-optic dosimeter to monitor the dose of ionizing radiation, both for instantaneous and integrating measurements, for radiotherapy applications is proposed. This fiber sensor is designed as an intracorporal X-ray ionizing sensor to enhance the curative effect of radiotherapy. The fiber-optic dosimeter is made in a PMMA fiber, whose core is micromachined to create a small diameter (0.25 to 0.5 mm) hole at one fiber end. An inorganic scintillating material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) is chosen as the sensing material, because it can fluoresce on immediately under exposure of ionizing radiation (X-Rays or electron beam). This sensing material is filled and packaged in the small hole by epoxy resin adhesive. This kind of novel structure dosimeter shows high light coupling efficiency compared with other kind of inorganic scintillation dosimeter. This fiber-optic dosimeter shows good repeatability with a maximum deviation of 0.16%. The testing results of the fiber-optic dosimeter are perfectly proportional to the data of IC with R2 as 0.9999. In addition, the fiber sensor shows excellent isotropic in its radial angular dependence. All the experiments indicate that the fiber-optic dosimeter is properly used for patient in-vivo dosimeter such as brachytherapy applications or intraoperative radiation therapy.

  2. Describing the direct and indirect radiative effects of atmospheric aerosols over Europe by using coupled meteorology-chemistry simulations: a contribution from the AQMEII-Phase II exercise

    NASA Astrophysics Data System (ADS)

    Jimenez-Guerrero, Pedro; Balzarini, Alessandra; Baró, Rocío; Curci, Gabriele; Forkel, Renate; Hirtl, Marcus; Honzak, Luka; Langer, Matthias; Pérez, Juan L.; Pirovano, Guido; San José, Roberto; Tuccella, Paolo; Werhahn, Johannes; Zabkar, Rahela

    2014-05-01

    The study of the response of the aerosol levels in the atmosphere to a changing climate and how this affects the radiative budget of the Earth (direct, semi-direct and indirect effects) is an essential topic to build confidence on climate science, since these feedbacks involve the largest uncertainties nowadays. Air quality-climate interactions (AQCI) are, therefore, a key, but uncertain contributor to the anthropogenic forcing that remains poorly understood. To build confidence in the AQCI studies, regional-scale integrated meteorology-atmospheric chemistry models (i.e., models with on-line chemistry) that include detailed treatment of aerosol life cycle and aerosol impacts on radiation (direct effects) and clouds (indirect effects) are in demand. In this context, the main objective of this contribution is the study and definition of the uncertainties in the climate-chemistry-aerosol-cloud-radiation system associated to the direct radiative forcing and the indirect effect caused by aerosols over Europe, using an ensemble of fully-coupled meteorology-chemistry model simulations with the WRF-Chem model run under the umbrella of AQMEII-Phase 2 international initiative. Simulations were performed for Europe for the entire year 2010. According to the common simulation strategy, the year was simulated as a sequence of 2-day time slices. For better comparability, the seven groups applied the same grid spacing of 23 km and shared common processing of initial and boundary conditions as well as anthropogenic and fire emissions. With exception of a simulation with different cloud microphysics, identical physics options were chosen while the chemistry options were varied. Two model set-ups will be considered here: one sub-ensemble of simulations not taking into account any aerosol feedbacks (the baseline case) and another sub-ensemble of simulations which differs from the former by the inclusion of aerosol-radiation feedback. The existing differences for meteorological

  3. Understanding Heterogeneous Chemistry at the Molecular-Level using Broadband Nonlinear Technologies: Application to Atmospheric Aerosol Growth and Chemistry

    NASA Astrophysics Data System (ADS)

    Allen, H. C.

    2001-12-01

    Surface reactions on liquid and solid particles can significantly impact tropospheric chemistry since many reactions that are slow to occur in the gas phase may in fact be favored on these atmospheric particles. Currently, we are investigating the surface structure of a variety of solid and liquid surfaces in order to understand particle growth and chemistry in the troposphere. The structure of a surface is different than the bulk media and consequently, the chemistry occurring at a surface is often unique. Surface vibrational sum frequency generation is the primary tool used in these studies because of its surface and molecular selectivity. New advances in our lab using broadband technology and ultra-fast laser sources for probing reactions taking place on surfaces on short timescales and at atmospheric pressures will be presented. Surface structures and adsorption of gas-phase water at the surface of various organic solutions (e.g. ethylene glycol and methylnapthalene) will be discussed.

  4. Impact of Climate Change on Soil and Groundwater Chemistry Subject to Process Waste Land Application

    NASA Astrophysics Data System (ADS)

    McNab, W. W.

    2013-12-01

    Nonhazardous aqueous process waste streams from food and beverage industry operations are often discharged via managed land application in a manner designed to minimize impacts to underlying groundwater. Process waste streams are typically characterized by elevated concentrations of solutes such as ammonium, organic nitrogen, potassium, sodium, and organic acids. Land application involves the mixing of process waste streams with irrigation water which is subsequently applied to crops. The combination of evapotranspiration and crop salt uptake reduces the downward mass fluxes of percolation water and salts. By carefully managing application schedules in the context of annual climatological cycles, growing seasons, and process requirements, potential adverse environmental impacts to groundwater can be mitigated. However, climate change poses challenges to future process waste land application efforts because the key factors that determine loading rates - temperature, evapotranspiration, seasonal changes in the quality and quantity of applied water, and various crop factors - are all likely to deviate from current averages. To assess the potential impact of future climate change on the practice of land application, coupled process modeling entailing transient unsaturated fluid flow, evapotranspiration, crop salt uptake, and multispecies reactive chemical transport was used to predict changes in salt loading if current practices are maintained in a warmer, drier setting. As a first step, a coupled process model (Hydrus-1D, combined with PHREEQC) was calibrated to existing data sets which summarize land application loading rates, soil water chemistry, and crop salt uptake for land disposal of process wastes from a food industry facility in the northern San Joaquin Valley of California. Model results quantify, for example, the impacts of evapotranspiration on both fluid flow and soil water chemistry at shallow depths, with secondary effects including carbonate mineral

  5. Effects of 20-MHz radiofrequency radiation on rat hematology splenic function, and serum chemistry

    SciTech Connect

    Wong, L.S.; Merritt, J.H.; Kiel, J.L.

    1985-08-01

    In this study, Sprague-Dawley rats were exposed in a TEM chamber to 20-MHz (HF-band) continuous-wave radiofrequency radiation (RFR) for 6 hr/days, 5 days/week up to 6 weeks. Randomly sampled rats killed on Days 8, 22, 39, and 42 after initiation of exposure showed no statistically significant difference from controls for body mass, spleen cell density, erythrocyte and leukocyte counts, hematocrit, hemoglobin, methemoglobin, erythrocyte fragility, bilirubin, creatinine, SGPT, alkaline phosphatase, calcium, sodium, potassium, and spleen cell chemiluminescence. Splenic mass differences were statistically significant only on Day 22. Spleen to body mass ratios differed significantly between exposed and control groups on Days 22 and 39. Histologic examination of the rats revealed the successive accumulation of phagocytic cells, lymphoid proliferation, development of lesions, and tissue necrosis characteristic of respiratory mycoplasmosis. In a followup experiment, a separate set of rats was exposed for 6 weeks to identical levels of RFR. No significant differences were found in splenic parameters and spleen cell peroxidative activity. Histologic examination of these animals revealed no evidence of mycoplasma infection. The observed differences between exposed and control animals of the first experiment appear to have resulted from subclinical respiratory mycoplasmosis rather than exposure to RFR.

  6. Radiation-resistant polymer-based photonics for space applications

    NASA Astrophysics Data System (ADS)

    Taylor, Edward W.; Nichter, James E.; Nash, Fazio; Haas, Franz; Szep, Attila A.; Michalak, Richard J.; Flusche, B.; Repak, Paul L.; Brost, George A.; Pirich, Andrew R.; Craig, Douglas M.; Le, Dang T.; Cardimona, David A.; Fetterman, Harold R.; Tsap, Boris; Castaneda, Carlos M.; Barto, Richard R.; Zeng, Tingying; Wood, David; Claus, Richard O.

    2004-10-01

    Empirical data regarding the radiation induced responses of Mach Zehnder interferometric electro-optic polymer based modulators (PBMs) operating at 1310 and 1550 nm and broadband InP quantum dot (QD) polymer photodetectors (PPDs) operating into the near infrared (NIR) are reported. Modulators composed of spun-on materials and hybrid electostatically self assembled (ESA) and spun-on NLO materials are examined for changes to their half-wave voltage and insertion losses following a gamma-ray total dose of 163 krad(Si) and irradiation by 25.6 MeV protons at a fluence of ~1011 cm-2. Pre- and post- irradiation responses of ESA grown polymer detectors using InP QDs are examined for photovoltage degradation and aging effects. The data indicates and excellent potential for developing polymer based photonic (PBP) devices with increased radiation resistance suitable for transition to photonic space applications.

  7. Anatomical models for space radiation applications: An overview

    NASA Astrophysics Data System (ADS)

    Atwell, W.

    1994-10-01

    Extremely detailed computerized anatomical male (CAM) and female (CAF) models that have been developed for use in space radiation analyses are discussed and reviewed. Recognizing that the level of detail may currently be inadequate for certain radiological applications, one of the purposes of this paper is to elicit specific model improvements or requirements from the scientific user-community. Methods and rationale are presented which describe the approach used in the Space Shuttle program to extrapolate dosimetry measurements (skin doses) to realistic astronaut body organ doses. Several mission scenarios are presented which demonstrate the utility of the anatomical models for obtaining specific body organ exposure estimates and can be used for establishing cancer morbidity and mortality risk assessments. These exposure estimates are based on the trapped Van Allen belt and galactic cosmic radiation environment models and data from the major historical solar particle events.

  8. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  9. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  10. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  11. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  12. 41 CFR 50-204.35 - Application for variations from radiation levels.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... variations from radiation levels. 50-204.35 Section 50-204.35 Public Contracts and Property Management Other... FOR FEDERAL SUPPLY CONTRACTS Radiation Standards § 50-204.35 Application for variations from radiation levels. (a) In accordance with policy expressed in the Federal Radiation Council's memorandum...

  13. Radiation grafted adsorbents for newly emerging environmental applications

    NASA Astrophysics Data System (ADS)

    Mahmoud Nasef, Mohamed; Ting, T. M.; Abbasi, Ali; Layeghi-moghaddam, Alireza; Sara Alinezhad, S.; Hashim, Kamaruddin

    2016-01-01

    Radiation induced grafting (RIG) is acquired to prepare a number of adsorbents for newly emerging environmental applications using a single route involving RIG of glycidymethacrylate (GMA) onto polyethylene-polypropylene (PE-PP) non-woven fabric. The grafted fabric was subjected to one of three functionalization reactions to impart desired ionic characters. This included treatment with (1) N-dimethyl-D-glucamine, (2) triethylamine and (3) triethylamine and alkalisation with KOH. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used to study the changes in chemical and physical structures of the obtained fibrous adsorbents. The potential applications of the three adsorbents for removal of boron from solutions, capturing CO2 from CO2/N2 mixtures and catalysing transesterification of triacetin/methanol to methyl acetate (biodiesel) were explored. The obtained fibrous adsorbents provide potential alternatives to granular resins for the investigated applications and require further development.

  14. CHEMISTRY IN THE FIRST HYDROSTATIC CORE STAGE BY ADOPTING THREE-DIMENSIONAL RADIATION HYDRODYNAMIC SIMULATIONS

    SciTech Connect

    Furuya, Kenji; Aikawa, Yuri; Tomida, Kengo; Tomisaka, Kohji; Matsumoto, Tomoaki; Saigo, Kazuya; Hersant, Franck; Wakelam, Valentine

    2012-10-20

    We investigate molecular evolution from a molecular cloud core to a first hydrostatic core in three spatial dimensions. We perform a radiation hydrodynamic simulation in order to trace fluid parcels, in which molecular evolution is investigated, using a gas-phase and grain-surface chemical reaction network. We derive spatial distributions of molecular abundances and column densities in the molecular cloud core harboring the first core. We find that the total gas and ice abundances of many species in a cold era (10 K) remain unaltered until the temperature reaches {approx}500 K. The gas abundances in the warm envelope and the outer layer of the first core (T {approx}< 500 K) are mainly determined via the sublimation of ice-mantle species. Above 500 K, the abundant molecules, such as H{sub 2}CO, start to be destroyed, and simple molecules, such as CO, H{sub 2}O, and N{sub 2}, are reformed. On the other hand, some molecules are effectively formed at high temperature; carbon chains, such as C{sub 2}H{sub 2} and cyanopolyynes, are formed at temperatures >700 K. We also find that large organic molecules, such as CH{sub 3}OH and HCOOCH{sub 3}, are associated with the first core (r {approx}< 10 AU). Although the abundances of these molecules in the first core stage are comparable to or less than in the protostellar stage (hot corino), reflecting the lower luminosity of the central object, their column densities in our model are comparable to the observed values toward the prototypical hot corino, IRAS 16293-2422. We propose that these large organic molecules can be good tracers of the first cores.

  15. Molecular Environmental Science Using Synchrotron Radiation: Chemistry and Physics of Waste Form Materials

    SciTech Connect

    Lindle, Dennis W.

    2011-04-21

    Production of defense-related nuclear materials has generated large volumes of complex chemical wastes containing a mixture of radionuclides. The disposition of these wastes requires conversion of the liquid and solid-phase components into durable, solid forms suitable for long-term immobilization. Specially formulated glass compositions and ceramics such as pyrochlores and apatites are the main candidates for these wastes. An important consideration linked to the durability of waste-form materials is the local structure around the waste components. Equally important is the local structure of constituents of the glass and ceramic host matrix. Knowledge of the structure in the waste-form host matrices is essential, prior to and subsequent to waste incorporation, to evaluate and develop improved waste-form compositions based on scientific considerations. This project used the soft-x-ray synchrotron-radiation-based technique of near-edge x-ray-absorption fine structure (NEXAFS) as a unique method for investigating oxidation states and structures of low-Z elemental constituents forming the backbones of glass and ceramic host matrices for waste-form materials. In addition, light metal ions in ceramic hosts, such as titanium, are also ideal for investigation by NEXAFS in the soft-x-ray region. Thus, one of the main objectives was to understand outstanding issues in waste-form science via NEXAFS investigations and to translate this understanding into better waste-form materials, followed by eventual capability to investigate “real” waste-form materials by the same methodology. We conducted several detailed structural investigations of both pyrochlore ceramic and borosilicate-glass materials during the project and developed improved capabilities at Beamline 6.3.1 of the Advanced Light Source (ALS) to perform the studies.

  16. Molecular environmental science using synchrotron radiation:Chemistry and physics of waste form materials

    SciTech Connect

    Lindle, Dennis W.; Shuh, David K.

    2005-02-28

    Production of defense-related nuclear materials has generated large volumes of complex chemical wastes containing a mixture of radionuclides. The disposition of these wastes requires conversion of the liquid and solid-phase components into durable, solid forms suitable for long-term immobilization [1]. Specially formulated glass compositions, many of which have been derived from glass developed for commercial purposes, and ceramics such as pyrochlores and apatites, will be the main recipients for these wastes. The performance characteristics of waste-form glasses and ceramics are largely determined by the loading capacity for the waste constituents (radioactive and non-radioactive) and the resultant chemical and radiation resistance of the waste-form package to leaching (durability). There are unique opportunities for the use of near-edge soft-x-ray absorption fine structure (NEXAFS) spectroscopy to investigate speciation of low-Z elements forming the backbone of waste-form glasses and ceramics. Although nuclear magnetic resonance (NMR) is the primary technique employed to obtain speciation information from low-Z elements in waste forms, NMR is incompatible with the metallic impurities contained in real waste and is thus limited to studies of idealized model systems. In contrast, NEXAFS can yield element-specific speciation information from glass constituents without sensitivity to paramagnetic species. Development and use of NEXAFS for eventual studies of real waste glasses has significant implications, especially for the low-Z elements comprising glass matrices [5-7]. The NEXAFS measurements were performed at Beamline 6.3.1, an entrance-slitless bend-magnet beamline operating from 200 eV to 2000 eV with a Hettrick-Underwood varied-line-space (VLS) grating monochromator, of the Advanced Light Source (ALS) at LBNL. Complete characterization and optimization of this beamline was conducted to enable high-performance measurements.

  17. Using Mathematical Software to Introduce Fourier Transforms in Physical Chemistry to Develop Improved Understanding of Their Applications in Analytical Chemistry

    ERIC Educational Resources Information Center

    Miller, Tierney C.; Richardson, John N.; Kegerreis, Jeb S.

    2016-01-01

    This manuscript presents an exercise that utilizes mathematical software to explore Fourier transforms in the context of model quantum mechanical systems, thus providing a deeper mathematical understanding of relevant information often introduced and treated as a "black-box" in analytical chemistry courses. The exercise is given to…

  18. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    SciTech Connect

    Sun, C.; Zheng, S.; Wei, C. C.; Wu, Y.; Shao, L.; Yang, Y.; Hartwig, K. T.; Maloy, S. A.; Zinkle, S. J.; Allen, T. R.; Wang, H.; Zhang, X.

    2015-01-15

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M₂₃C₆ precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

  19. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    DOE PAGES

    Sun, C.; Zheng, S.; Wei, C. C.; ...

    2015-01-15

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size ofmore » ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M₂₃C₆ precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.« less

  20. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    NASA Astrophysics Data System (ADS)

    Sun, C.; Zheng, S.; Wei, C. C.; Wu, Y.; Shao, L.; Yang, Y.; Hartwig, K. T.; Maloy, S. A.; Zinkle, S. J.; Allen, T. R.; Wang, H.; Zhang, X.

    2015-01-01

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M23C6 precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

  1. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments.

    PubMed

    Sun, C; Zheng, S; Wei, C C; Wu, Y; Shao, L; Yang, Y; Hartwig, K T; Maloy, S A; Zinkle, S J; Allen, T R; Wang, H; Zhang, X

    2015-01-15

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304 L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500 °C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M(23)C(6) precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

  2. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    PubMed Central

    Sun, C.; Zheng, S.; Wei, C. C.; Wu, Y.; Shao, L.; Yang, Y.; Hartwig, K. T.; Maloy, S. A.; Zinkle, S. J.; Allen, T. R.; Wang, H.; Zhang, X.

    2015-01-01

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M23C6 precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments. PMID:25588326

  3. Statistical rate theory and kinetic energy-resolved ion chemistry: theory and applications.

    PubMed

    Armentrout, P B; Ervin, Kent M; Rodgers, M T

    2008-10-16

    Ion chemistry, first discovered 100 years ago, has profitably been coupled with statistical rate theories, developed about 80 years ago and refined since. In this overview, the application of statistical rate theory to the analysis of kinetic-energy-dependent collision-induced dissociation (CID) reactions is reviewed. This procedure accounts for and quantifies the kinetic shifts that are observed as systems increase in size. The statistical approach developed allows straightforward extension to systems undergoing competitive or sequential dissociations. Such methods can also be applied to the reverse of the CID process, association reactions, as well as to quantitative analysis of ligand exchange processes. Examples of each of these types of reactions are provided and the literature surveyed for successful applications of this statistical approach to provide quantitative thermochemical information. Such applications include metal-ligand complexes, metal clusters, proton-bound complexes, organic intermediates, biological systems, saturated organometallic complexes, and hydrated and solvated species.

  4. Surface chemistry manipulation of gold nanorods preserves optical properties for bio-imaging applications

    NASA Astrophysics Data System (ADS)

    Polito, Anthony B.; Maurer-Gardner, Elizabeth I.; Hussain, Saber M.

    2015-12-01

    Due to their anisotropic shape, gold nanorods (GNRs) possess a number of advantages for biosystem use including, enhanced surface area and tunable optical properties within the near-infrared (NIR) region. However, cetyl trimethylammonium bromide-related cytotoxicity, overall poor cellular uptake following surface chemistry modifications, and loss of NIR optical properties due to material intracellular aggregation in combination remain as obstacles for nanobased biomedical GNR applications. In this article, we report that tannic acid-coated 11-mercaptoundecyl trimethylammonium bromide (MTAB) GNRs (MTAB-TA) show no significant decrease in either in vitro cell viability or stress activation after exposures to A549 human alveolar epithelial cells. In addition, MTAB-TA GNRs demonstrate a substantial level of cellular uptake while displaying a unique intracellular clustering pattern. This clustering pattern significantly reduces intracellular aggregation, preserving the GNRs NIR optical properties, vital for biomedical imaging applications. These results demonstrate how surface chemistry modifications enhance biocompatibility, allow for higher rate of internalization with low intracellular aggregation of MTAB-TA GNRs, and identify them as prime candidates for use in nanobased bio-imaging applications.

  5. Graphene-based materials: fabrication and application for adsorption in analytical chemistry.

    PubMed

    Wang, Xin; Liu, Bo; Lu, Qipeng; Qu, Qishu

    2014-10-03

    Graphene, a single layer of carbon atoms densely packed into a honeycomb crystal lattice with unique electronic, chemical, and mechanical properties, is the 2D allotrope of carbon. Owing to the remarkable properties, graphene and graphene-based materials are likely to find potential applications as a sorbent in analytical chemistry. The current review focuses predominantly on the recent development of graphene-based materials and demonstrates their enhanced performance in adsorption of organic compounds, metal ions, and solid phase extraction as well as in separation science since mostly 2012.

  6. Recent Advances in Boron-Substituted 1,3-Dienes Chemistry: Synthesis and Application.

    PubMed

    Pyziak, Jadwiga; Walkowiak, Jędrzej; Marciniec, Bogdan

    2017-03-13

    In the syntheses developed to access naturally occurring compounds, especially bioactive substances, boron-functionalized dienes (also "linchpin" reagents) are used as key reagents. Structurally unique dienes are found in nature, and play important biological and chemical roles. Recently, linchpin moieties have been proved as useful substrates for a variety of highly functionalized chemical transformations. The products of these processes are potentially of some use for the syntheses of an important class of natural products showing a wide range of biological activities. This review describes progress in the synthesis of borylsubstituted buta-1,3-dienes as well as their application in organic chemistry.

  7. Nonlinear aspects of acoustic radiation force in biomedical applications

    SciTech Connect

    Ostrovsky, Lev; Tsyuryupa, Sergey; Sarvazyan, Armen

    2015-10-28

    In the past decade acoustic radiation force (ARF) became a powerful tool in numerous biomedical applications. ARF from a focused ultrasound beam acts as a virtual “finger” for remote probing of internal anatomical structures and obtaining diagnostic information. This presentation deals with generation of shear waves by nonlinear focused beams. Albeit the ARF has intrinsically nonlinear origin, in most cases the primary ultrasonic wave was considered in the linear approximation. In this presentation, we consider the effects of nonlinearly distorted beams on generation of shear waves by such beams.

  8. Radiation Heat Transfer Procedures for Space-Related Applications

    NASA Technical Reports Server (NTRS)

    Chai, John C.

    2000-01-01

    Over the last contract year, a numerical procedure for combined conduction-radiation heat transfer using unstructured grids has been developed. As a result of this research, one paper has been published in the Numerical Heat Transfer Journal. One paper has been accepted for presentation at the International Center for Heat and Mass Transfer's International Symposium on Computational Heat Transfer to be held in Australia next year. A journal paper is under review by my NASA's contact. A conference paper for the ASME National Heat Transfer conference is under preparation. In summary, a total of four (4) papers (two journal and two conference) have been published, accepted or are under preparation. There are two (2) to three (3) more papers to be written for the project. In addition to the above publications, one book chapter, one journal paper and six conference papers have been published as a result of this project. Over the last contract year, the research project resulted in one Ph.D. thesis and partially supported another Ph.D. student. My NASA contact and myself have formulated radiation heat transfer procedures for materials with different indices of refraction and for combined conduction-radiation heat transfer. We are trying to find other applications for the procedures developed under this grant.

  9. Carbon nanotubes buckypaper radiation studies for medical physics applications.

    PubMed

    Alanazi, Abdulaziz; Alkhorayef, Mohammed; Alzimami, Khalid; Jurewicz, Izabela; Abuhadi, Nouf; Dalton, Alan; Bradley, D A

    2016-11-01

    Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In such circumstance, dosimeters with atomic number similar to human tissue are needed. Carbon nanotubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nanotubes (SWCNTs) buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2Gy. This finding suggests that carbon nanotubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance.

  10. Industrial radiation and radioisotope gauging techniques and applications

    SciTech Connect

    Gardner, R.P.

    1997-12-01

    The radiation and radioisotope gauging industry in the United States has primarily followed a path of development solely by the private sector. It has remained highly proprietary in nature, which is opposite to the path taken by many other countries. In other countries radiation gauge development has been controlled in large part by government-sponsored research and development, which has spawned many more publications in the open literature. Historically, some of the leaders have been Great Britain, Poland, France, Russia, and Australia. This has possibly led to the misconception that the development of this technology is being dominated by countries outside the United States. This is not a healthy situation-it would be good to see our industry begin to publish more in the open literature and to sponsor more research at universities. In efforts to promote more open-literature publication, the American Nuclear Society (ANS) sponsored a topical meeting on Industrial Radiation and Radioisotope Measurement Applications (IRRMA) in 1988 that was held again in 1992.

  11. Bidirectional Reflectance Functions for Application to Earth Radiation Budget Studies

    NASA Technical Reports Server (NTRS)

    Manalo-Smith, N.; Tiwari, S. N.; Smith, G. L.

    1997-01-01

    Reflected solar radiative fluxes emerging for the Earth's top of the atmosphere are inferred from satellite broadband radiance measurements by applying bidirectional reflectance functions (BDRFs) to account for the anisotropy of the radiation field. BDRF's are dependent upon the viewing geometry (i.e. solar zenith angle, view zenith angle, and relative azimuth angle), the amount and type of cloud cover, the condition of the intervening atmosphere, and the reflectance characteristics of the underlying surface. A set of operational Earth Radiation Budget Experiment (ERBE) BDRFs is available which was developed from the Nimbus 7 ERB (Earth Radiation Budget) scanner data for a three-angle grid system, An improved set of bidirectional reflectance is required for mission planning and data analysis of future earth radiation budget instruments, such as the Clouds and Earth's Radiant Energy System (CERES), and for the enhancement of existing radiation budget data products. This study presents an analytic expression for BDRFs formulated by applying a fit to the ERBE operational model tabulations. A set of model coefficients applicable to any viewing condition is computed for an overcast and a clear sky scene over four geographical surface types: ocean, land, snow, and desert, and partly cloudy scenes over ocean and land. The models are smooth in terms of the directional angles and adhere to the principle of reciprocity, i.e., they are invariant with respect to the interchange of the incoming and outgoing directional angles. The analytic BDRFs and the radiance standard deviations are compared with the operational ERBE models and validated with ERBE data. The clear ocean model is validated with Dlhopolsky's clear ocean model. Dlhopolsky developed a BDRF of higher angular resolution for clear sky ocean from ERBE radiances. Additionally, the effectiveness of the models accounting for anisotropy for various viewing directions is tested with the ERBE along tract data. An area

  12. Novel biomedical applications of Cerenkov radiation and radioluminescence imaging.

    PubMed

    Spinelli, Antonello E; Boschi, Federico

    2015-03-01

    The main goals of this review is to provide an up-to-date account of the different uses of Cerenkov radiation (CR) and radioluminescence imaging for pre-clinical small animal imaging. We will focus on new emerging applications such as the use of Cerenkov imaging for monitoring radionuclide and external radiotherapy in humans. Another novel application that will be described is the monitoring of radiochemical synthesis using microfluidic chips. Several pre-clinical aspects of CR will be discussed such as the development of 3D reconstruction methods for Cerenkov images and the use of CR as excitation source for nanoparticles or for endoscopic imaging. We will also include a discussion on radioluminescence imaging that is a more general method than Cerenkov imaging for the detection using optical methods of alpha and gamma emitters.

  13. An exploratory study of proficient undergraduate Chemistry II students' application of Lewis's model

    NASA Astrophysics Data System (ADS)

    Lewis, Sumudu R.

    cases where the algorithm cannot be applied. Additionally, the proficient students' understanding (i.e., representation, explanation and application) of the Valence Shell Electron-Pair Repulsion theory was accurate and precise, and they used the key terms in the correct context when explaining their reasoning. The results of this study can be of great importance to general chemistry and organic chemistry courses' instructors. This study identified students' baseline academic skills and abilities that lead to conceptual understanding of the essential concepts of covalent bonding and molecule structure, which instructors could use as a guide for developing instruction. Furthermore knowing the effective methods of reasoning the students use while applying Lewis's model, the instructors may be better informed and be able to better facilitate students' learning of Lewis' model and its application. Finally, the ideas and methods used in this study can be of value to chemistry education researchers to learn more about developing proficiency through reasoning methods in other chemistry concepts.

  14. Applications of Cherenkov Light Emission for Dosimetry in Radiation Therapy

    NASA Astrophysics Data System (ADS)

    Glaser, Adam Kenneth

    Since its discovery in the 1930's, the Cherenkov effect has been paramount in the development of high-energy physics research. It results in light emission from charged particles traveling faster than the local speed of light in a dielectric medium. The ability of this emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, only recently has the phenomenon been considered in the practical context of medical physics and radiation therapy dosimetry, where Cherenkov light is induced by clinical x-ray photon, electron, and proton beams. To investigate the relationship between this phenomenon and dose deposition, a Monte Carlo plug-in was developed within the Geant4 architecture for medically-oriented simulations (GAMOS) to simulate radiation-induced optical emission in biological media. Using this simulation framework, it was determined that Cherenkov light emission may be well suited for radiation dosimetry of clinically used x-ray photon beams. To advance this application, several novel techniques were implemented to realize the maximum potential of the signal, such as time-gating for maximizing the signal to noise ratio (SNR) and Cherenkov-excited fluorescence for generating isotropic light release in water. Proof of concept experiments were conducted in water tanks to demonstrate the feasibility of the proposed method for two-dimensional (2D) projection imaging, three-dimensional (3D) parallel beam tomography, large field of view 3D cone beam tomography, and video-rate dynamic imaging of treatment plans for a number of common radiotherapy applications. The proposed dosimetry method was found to have a number of unique advantages, including but not limited to its non-invasive nature, water-equivalence, speed, high-resolution, ability to provide full 3D data, and potential to yield data in-vivo. Based on

  15. JPRS Report, Science & Technology, USSR: Chemistry

    DTIC Science & Technology

    2007-11-02

    This report contains foreign media information from the USSR concerning analytical chemistry, catalysis, electrochemistry, inorganic compounds, organometallic compounds, organophosphorous compounds, polymers and radiation chemistry.

  16. JPRS Report, Science & Technology, USSR: Chemistry.

    DTIC Science & Technology

    2007-11-02

    Partial Contents: Catalysis, Chemical Industry, Electrochemistry, Environmental Chemistry, Materials Research, Organophosphorous Compounds, Petroleum and Coal Processing, Polymers and Rubber, Radiation Chemistry.

  17. Fundamental surface processes in heterogeneous atmospheric chemistry: Applications to sea-salt (NaCl) and oxide particulate chemistry

    NASA Astrophysics Data System (ADS)

    Allen, Heather Cecile

    1997-10-01

    Although heterogeneous phenomena are important in many atmospheric processes, these complex systems have been difficult to study at the fundamental level. Surface- sensitive techniques are currently being utilized to probe the chemistry of heterogeneous atmospheric systems. In addition to presenting fundamental surface chemistry of several systems, this dissertation shows that surface- sensitive and electron microscopy technology can provide substantial insight into heterogeneous atmospheric processes. Transmission electron microscopy and energy dispersive spectroscopy (TEM-EDS) were used to better understand fundamental mechanisms of the reaction of sodium chloride with nitric acid vapor (and reaction with nitrogen dioxide) followed by water vapor. Results show for the first time that exposures to water vapor can lead to major reconstruction and concurrent recrystallization of the surface after reaction of NaCl(s) with HNO3(g). This has significant implications for tropospheric chemistry in polluted urban regions. The entire volume of airborne sea-salt (i.e. NaCl) particles is available for reaction due to the water-induced reorganization of the surface. Additional studies presented here include: (1) Laser induced desorption-Fourier transform mass spectrometry (LID-FTMS) studies of the reactivity of thin films of aluminum oxide (γ- Al2O3/NiAl(100)) after exposure to molecules relevant to tropospheric and stratospheric particulate chemistry, (2) TEM-EDS studies of stratospheric particles, and (3) Thermal desorption spectroscopy (TDS) of CO/NiAl(100). TDS and LID-FTMS studies reveal that non-hydroxylated γ- Al2O3/NiAl(100) is inert toward the adsorption of CF2Cl2 and HCF2Cl. LID-FTMS results show that 1,3-butadiene desorbs intact from non- hydroxylated γ- Al2O3/NiAl(100) at ~200 K. The TEM-EDS studies of stratospheric particles reveal that submicron alumina spheres are amorphous. Previous studies of submicron alumina spheres showed that γ-alumina was the

  18. Nanoporous Anodic Alumina Platforms: Engineered Surface Chemistry and Structure for Optical Sensing Applications

    PubMed Central

    Kumeria, Tushar; Santos, Abel; Losic, Dusan

    2014-01-01

    Electrochemical anodization of pure aluminum enables the growth of highly ordered nanoporous anodic alumina (NAA) structures. This has made NAA one of the most popular nanomaterials with applications including molecular separation, catalysis, photonics, optoelectronics, sensing, drug delivery, and template synthesis. Over the past decades, the ability to engineer the structure and surface chemistry of NAA and its optical properties has led to the establishment of distinctive photonic structures that can be explored for developing low-cost, portable, rapid-response and highly sensitive sensing devices in combination with surface plasmon resonance (SPR) and reflective interference spectroscopy (RIfS) techniques. This review article highlights the recent advances on fabrication, surface modification and structural engineering of NAA and its application and performance as a platform for SPR- and RIfS-based sensing and biosensing devices. PMID:25004150

  19. Nanoporous anodic alumina platforms: engineered surface chemistry and structure for optical sensing applications.

    PubMed

    Kumeria, Tushar; Santos, Abel; Losic, Dusan

    2014-07-07

    Electrochemical anodization of pure aluminum enables the growth of highly ordered nanoporous anodic alumina (NAA) structures. This has made NAA one of the most popular nanomaterials with applications including molecular separation, catalysis, photonics, optoelectronics, sensing, drug delivery, and template synthesis. Over the past decades, the ability to engineer the structure and surface chemistry of NAA and its optical properties has led to the establishment of distinctive photonic structures that can be explored for developing low-cost, portable, rapid-response and highly sensitive sensing devices in combination with surface plasmon resonance (SPR) and reflective interference spectroscopy (RIfS) techniques. This review article highlights the recent advances on fabrication, surface modification and structural engineering of NAA and its application and performance as a platform for SPR- and RIfS-based sensing and biosensing devices.

  20. Evaluation of Radiative Kernels for Albedo Radiative Forcing Calculations Using CERES Satellite Observations: Applications for the LULCC Community

    NASA Astrophysics Data System (ADS)

    O'Halloran, T. L.; Bright, R. M.

    2015-12-01

    Modifications to the land surface that alter surface albedo consequently change the radiation balance of the planet, and therefore have the potential to modify climate. To quantify this "radiative forcing", researchers in the land use/ land cover change community must calculate the change in the top-of-the-atmosphere (TOA) shortwave radiative flux associated with measured or modeled changes in surface albedo. Conventional solutions to this problem include application of radiative transfer models that require detailed inputs of vertical profiles of cloud properties and atmospheric gas and particle concentrations. Performing these calculations can be logistically complex and computationally intensive. As biogeophysical effects of land use change are increasingly included into climate mitigation strategies, a need has arisen for efficient means of making these calculations. "Radiative kernels", which are essentially climatologies of the sensitivity of TOA fluxes to changes in surface albedo, as developed using offline calculations of the radiative transfer code inside a global climate model, have become popular options. However, satellite observations of TOA radiative fluxes may be applied with simple models to provide an attractive measurement-based alternative to radiative kernels. The Clouds and the Earth's Radiant Energy System (CERES) instruments provide approximately 15 years (and growing) of remotely-sensed observations of TOA fluxes. Here we evaluate popular radiative kernels with CERES observations, and provide an empirical alternative for calculating TOA radiative forcing from surface albedo change using CERES data.

  1. Comparison of nine different real-time PCR chemistries for qualitative and quantitative applications in GMO detection.

    PubMed

    Buh Gasparic, Meti; Tengs, Torstein; La Paz, Jose Luis; Holst-Jensen, Arne; Pla, Maria; Esteve, Teresa; Zel, Jana; Gruden, Kristina

    2010-03-01

    Several techniques have been developed for detection and quantification of genetically modified organisms, but quantitative real-time PCR is by far the most popular approach. Among the most commonly used real-time PCR chemistries are TaqMan probes and SYBR green, but many other detection chemistries have also been developed. Because their performance has never been compared systematically, here we present an extensive evaluation of some promising chemistries: sequence-unspecific DNA labeling dyes (SYBR green), primer-based technologies (AmpliFluor, Plexor, Lux primers), and techniques involving double-labeled probes, comprising hybridization (molecular beacon) and hydrolysis (TaqMan, CPT, LNA, and MGB) probes, based on recently published experimental data. For each of the detection chemistries assays were included targeting selected loci. Real-time PCR chemistries were subsequently compared for their efficiency in PCR amplification and limits of detection and quantification. The overall applicability of the chemistries was evaluated, adding practicability and cost issues to the performance characteristics. None of the chemistries seemed to be significantly better than any other, but certain features favor LNA and MGB technology as good alternatives to TaqMan in quantification assays. SYBR green and molecular beacon assays can perform equally well but may need more optimization prior to use.

  2. Development and application of the High resolution VOC Atmospheric Chemistry in Canopies (Hi-VACC) model

    NASA Astrophysics Data System (ADS)

    Kenny, W.; Bohrer, G.; Chatziefstratiou, E.

    2013-12-01

    We have been working to develop a new post-processing model - High resolution VOC Atmospheric Chemistry in Canopies (Hi-VACC) - which will be able to resolve the dispersion and chemistry of reacting chemical species given their emission rates from the vegetation and soil, driven by high resolution meteorological forcing and wind fields from various high resolution atmospheric regional and large-eddy simulations. Hi-VACC reads in fields of pressure, temperature, humidity, air density, short-wave radiation, wind (3-D u, v and w components) and sub-grid-scale turbulence that were simulated by a high resolution atmospheric model. This meteorological forcing data is provided as snapshots of 3-D fields. Presently, the advection-diffusion portion of the model is fully developed, and we have tested it using a number of RAMS-based Forest Large Eddy Simulation (RAFLES) runs. Here, we present results from utilizing Hi-VACC in a few different contexts where it performs smoke and particle dispersion well. These include simulations of smoke dispersion from a theoretical forest fire in a domain in The Pine Barrens in New Jersey, as well as simulations to test the effects of heat flux on a scalar plume dispersing over a vegetative windbreak in an agricultural setting. Additional, we show initial results from testing the coupled chemistry component of Hi-VACC. One of the primary benefits of Hi-VACC is that users of other models can utilize this tool with only minimal work on their part -- processing their output fields into the appropriate HI-VACC input format. We have developed our model such that for whatever atmospheric model is being used with it, a MATLAB function must be written to extract the necessary information from the output files of that model and shape it into the proper format. This is the only model-specific work required. As such, this sort of smoke dispersion modeling performed by Hi-VACC - as well as its other capabilities - can be easily performed in other

  3. A radiation-hardened, computer for satellite applications

    SciTech Connect

    Gaona, J.I. Jr.

    1996-08-01

    This paper describes high reliability radiation hardened computers built by Sandia for application aboard DOE satellite programs requiring 32 bit processing. The computers highlight a radiation hardened (10 kGy(Si)) R3000 executing up to 10 million reduced instruction set instructions (RISC) per second (MIPS), a dual purpose module control bus used for real-time default and power management which allows for extended mission operation on as little as 1.2 watts, and a local area network capable of 480 Mbits/s. The central processing unit (CPU) is the NASA Goddard R3000 nicknamed the ``Mongoose or Mongoose 1``. The Sandia Satellite Computer (SSC) uses Rational`s Ada compiler, debugger, operating system kernel, and enhanced floating point emulation library targeted at the Mongoose. The SSC gives Sandia the capability of processing complex types of spacecraft attitude determination and control algorithms and of modifying programmed control laws via ground command. And in general, SSC offers end users the ability to process data onboard the spacecraft that would normally have been sent to the ground which allows reconsideration of traditional space-grounded partitioning options.

  4. Orthogonal spin labeling using click chemistry for in vitro and in vivo applications.

    PubMed

    Kucher, Svetlana; Korneev, Sergei; Tyagi, Swati; Apfelbaum, Ronja; Grohmann, Dina; Lemke, Edward A; Klare, Johann P; Steinhoff, Heinz-Jürgen; Klose, Daniel

    2017-02-01

    Site-directed spin labeling for EPR- and NMR spectroscopy has mainly been achieved exploiting the specific reactivity of cysteines. For proteins with native cysteines or for in vivo applications, an alternative coupling strategy is required. In these cases click chemistry offers major benefits by providing a fast and highly selective, biocompatible reaction between azide and alkyne groups. Here, we establish click chemistry as a tool to target unnatural amino acids in vitro and in vivo using azide- and alkyne-functionalized spin labels. The approach is compatible with a variety of labels including reduction-sensitive nitroxides. Comparing spin labeling efficiencies from the copper-free with the strongly reducing copper(I)-catalyzed azide-alkyne click reaction, we find that the faster kinetics for the catalyzed reaction outrun reduction of the labile nitroxide spin labels and allow quantitative labeling yields within short reaction times. Inter-spin distance measurements demonstrate that the novel side chain is suitable for paramagnetic NMR- or EPR-based conformational studies of macromolecular complexes.

  5. On the applicability of one- and many-electron quantum chemistry models for hydrated electron clusters.

    PubMed

    Turi, László

    2016-04-21

    We evaluate the applicability of a hierarchy of quantum models in characterizing the binding energy of excess electrons to water clusters. In particular, we calculate the vertical detachment energy of an excess electron from water cluster anions with methods that include one-electron pseudopotential calculations, density functional theory(DFT) based calculations, and ab initio quantum chemistry using MP2 and eom-EA-CCSD levels of theory. The examined clusters range from the smallest cluster size (n = 2) up to nearly nanosize clusters with n = 1000 molecules. The examined cluster configurations are extracted from mixed quantum-classical molecular dynamics trajectories of cluster anions with n = 1000 water molecules using two different one-electron pseudopotenial models. We find that while MP2 calculations with large diffuse basis set provide a reasonable description for the hydrated electron system, DFT methods should be used with precaution and only after careful benchmarking. Strictly tested one-electron psudopotentials can still be considered as reasonable alternatives to DFT methods, especially in large systems. The results of quantum chemistry calculations performed on configurations, that represent possible excess electron binding motifs in the clusters, appear to be consistent with the results using a cavitystructure preferring one-electron pseudopotential for the hydrated electron, while they are in sharp disagreement with the structural predictions of a non-cavity model.

  6. Orthogonal spin labeling using click chemistry for in vitro and in vivo applications

    NASA Astrophysics Data System (ADS)

    Kucher, Svetlana; Korneev, Sergei; Tyagi, Swati; Apfelbaum, Ronja; Grohmann, Dina; Lemke, Edward A.; Klare, Johann P.; Steinhoff, Heinz-Jürgen; Klose, Daniel

    2017-02-01

    Site-directed spin labeling for EPR- and NMR spectroscopy has mainly been achieved exploiting the specific reactivity of cysteines. For proteins with native cysteines or for in vivo applications, an alternative coupling strategy is required. In these cases click chemistry offers major benefits by providing a fast and highly selective, biocompatible reaction between azide and alkyne groups. Here, we establish click chemistry as a tool to target unnatural amino acids in vitro and in vivo using azide- and alkyne-functionalized spin labels. The approach is compatible with a variety of labels including reduction-sensitive nitroxides. Comparing spin labeling efficiencies from the copper-free with the strongly reducing copper(I)-catalyzed azide-alkyne click reaction, we find that the faster kinetics for the catalyzed reaction outrun reduction of the labile nitroxide spin labels and allow quantitative labeling yields within short reaction times. Inter-spin distance measurements demonstrate that the novel side chain is suitable for paramagnetic NMR- or EPR-based conformational studies of macromolecular complexes.

  7. Applications of monolithic solid-phase extraction in chromatography-based clinical chemistry assays.

    PubMed

    Bunch, Dustin R; Wang, Sihe

    2013-04-01

    Complex matrices, for example urine, serum, plasma, and whole blood, which are common in clinical chemistry testing, contain many non-analyte compounds that can interfere with either detection or in-source ionization in chromatography-based assays. To overcome this problem, analytes are extracted by protein precipitation, solid-phase extraction (SPE), and liquid-liquid extraction. With correct chemistry and well controlled material SPE may furnish clean specimens with consistent performance. Traditionally, SPE has been performed with particle-based adsorbents, but monolithic SPE is attracting increasing interest of clinical laboratories. Monoliths, solid pieces of stationary phase, have bimodal structures consisting of macropores, which enable passage of solvent, and mesopores, in which analytes are separated. This structure results in low back-pressure with separation capabilities similar to those of particle-based adsorbents. Monoliths also enable increased sample throughput, reduced solvent use, varied support formats, and/or automation. However, many of these monoliths are not commercially available. In this review, application of monoliths to purification of samples from humans before chromatography-based assays will be critically reviewed.

  8. Application of the Spectral Element Method to Acoustic Radiation

    NASA Technical Reports Server (NTRS)

    Doyle, James F.; Rizzi, Stephen A. (Technical Monitor)

    2000-01-01

    This report summarizes research to develop a capability for analysis of interior noise in enclosed structures when acoustically excited by an external random source. Of particular interest was the application to the study of noise and vibration transmission in thin-walled structures as typified by aircraft fuselages. Three related topics are focused upon. The first concerns the development of a curved frame spectral element, the second shows how the spectral element method for wave propagation in folded plate structures is extended to problems involving curved segmented plates. These are of significance because by combining these curved spectral elements with previously presented flat spectral elements, the dynamic response of geometrically complex structures can be determined. The third topic shows how spectral elements, which incorporate the effect of fluid loading on the structure, are developed for analyzing acoustic radiation from dynamically loaded extended plates.

  9. Some Properties of Poly(Methyl Methacrylate) Studied by Radiation Degradation: An Interdisciplinary Student Experiment.

    ERIC Educational Resources Information Center

    Hill, D. J. T.; O'Donnell, J. H.

    1981-01-01

    Describes an interdisciplinary student experiment based upon the radiation effects on polymers, integrating some of the fundamentals of radiation chemistry, polymer chemistry, and material science. Also demonstrates how the information gained in the experiment has direct commercial application in product manufacture or processing. (CS)

  10. Application of radiation processing in asia and the pacific region: Focus on malaysia

    NASA Astrophysics Data System (ADS)

    Mohd Dahlan, Khairul Zaman HJ.

    1995-09-01

    Applications of radiation processing in Malaysia and other developing countries in Asia and the Pacific region is increasing as the countries move toward industrialisation. At present, there are more than 85 gamma facilities and 334 electron accelerators in Asia and the Pacific region which are mainly in Japan, Rep. of Korea and China. The main applications which are in the interest of the region are radiation sterilisation of medical products; radiation crosslinking of wire and cable, heat shrinkable film and tube, and foam; radiation curing of surface coatings, printing inks and adhesive; radiation vulcanisation of natural rubber latex; radiation processing of agro-industrial waste; radiation treatment of sewage sludge and municipal waste; food irradiation; tissue grafts and radiation synthesis of bioactive materials.

  11. On determining important aspects of mathematical models: Application to problems in physics and chemistry

    NASA Technical Reports Server (NTRS)

    Rabitz, Herschel

    1987-01-01

    The use of parametric and functional gradient sensitivity analysis techniques is considered for models described by partial differential equations. By interchanging appropriate dependent and independent variables, questions of inverse sensitivity may be addressed to gain insight into the inversion of observational data for parameter and function identification in mathematical models. It may be argued that the presence of a subset of dominantly strong coupled dependent variables will result in the overall system sensitivity behavior collapsing into a simple set of scaling and self similarity relations amongst elements of the entire matrix of sensitivity coefficients. These general tools are generic in nature, but herein their application to problems arising in selected areas of physics and chemistry is presented.

  12. Water-soluble NHC-Cu catalysts: applications in click chemistry, bioconjugation and mechanistic analysis.

    PubMed

    Díaz Velázquez, Heriberto; Ruiz García, Yara; Vandichel, Matthias; Madder, Annemieke; Verpoort, Francis

    2014-12-14

    Copper(I)-catalyzed 1,3-dipolar cycloaddition of azides and terminal alkynes (CuAAC), better known as "click" reaction, has triggered the use of 1,2,3-triazoles in bioconjugation, drug discovery, materials science and combinatorial chemistry. Here we report a new series of water-soluble catalysts based on N-heterocyclic carbene (NHC)-Cu complexes which are additionally functionalized with a sulfonate group. The complexes show superior activity towards CuAAC reactions and display a high versatility, enabling the production of triazoles with different substitution patterns. Additionally, successful application of these complexes in bioconjugation using unprotected peptides acting as DNA binding domains was achieved for the first time. Mechanistic insight into the reaction mechanism is obtained by means of state-of-the-art first principles calculations.

  13. Investigation of Trends in Aerosol Direct Radiative Effects over North America Using a Coupled Meteorology-Chemistry Model

    EPA Science Inventory

    A comprehensive investigation of the processes regulating tropospheric aerosol distributions, their optical properties, and their radiative effects in conjunction with verification of their simulated radiative effects for past conditions relative to measurements is needed in orde...

  14. Application of Interval Predictor Models to Space Radiation Shielding

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Kenny, Sean P.; Giesy,Daniel P.; Norman, Ryan B.; Blattnig, Steve R.

    2016-01-01

    This paper develops techniques for predicting the uncertainty range of an output variable given input-output data. These models are called Interval Predictor Models (IPM) because they yield an interval valued function of the input. This paper develops IPMs having a radial basis structure. This structure enables the formal description of (i) the uncertainty in the models parameters, (ii) the predicted output interval, and (iii) the probability that a future observation would fall in such an interval. In contrast to other metamodeling techniques, this probabilistic certi cate of correctness does not require making any assumptions on the structure of the mechanism from which data are drawn. Optimization-based strategies for calculating IPMs having minimal spread while containing all the data are developed. Constraints for bounding the minimum interval spread over the continuum of inputs, regulating the IPMs variation/oscillation, and centering its spread about a target point, are used to prevent data over tting. Furthermore, we develop an approach for using expert opinion during extrapolation. This metamodeling technique is illustrated using a radiation shielding application for space exploration. In this application, we use IPMs to describe the error incurred in predicting the ux of particles resulting from the interaction between a high-energy incident beam and a target.

  15. Converting STEM Doctoral Dissertations into Patent Applications: A Study of Chemistry, Physics, Mathematics, and Chemical Engineering Dissertations from CIC Institutions

    ERIC Educational Resources Information Center

    Butkovich, Nancy J.

    2015-01-01

    Doctoral candidates may request short-term embargoes on the release of their dissertations in order to apply for patents. This study examines how often inventions described in dissertations in chemical engineering, chemistry, physics, and mathematics are converted into U.S. patent applications, as well as the relationship between dissertation…

  16. Sol-Gel Application for Consolidating Stone: An Example of Project-Based Learning in a Physical Chemistry Lab

    ERIC Educational Resources Information Center

    de los Santos, Desiree´ M.; Montes, Antonio; Sa´nchez-Coronilla, Antonio; Navas, Javier

    2014-01-01

    A Project Based Learning (PBL) methodology was used in the practical laboratories of the Advanced Physical Chemistry department. The project type proposed simulates "real research" focusing on sol-gel synthesis and the application of the obtained sol as a stone consolidant. Students were divided into small groups (2 to 3 students) to…

  17. High permittivity patch radiator for single and multi-element hyperthermia applicators.

    PubMed

    Andreuccetti, D; Bini, M; Ignesti, A; Olmi, R; Priori, S; Vanni, R

    1993-07-01

    This paper describes a compact, low-profile patch radiator which is the base element for efficient, small-size applicators suitable for superficial hyperthermia. The design criteria and the technological processes involved are presented. The electromagnetic characteristics of the patch element are outlined, and possible application of the radiator are discussed.

  18. Development of new methods and polyphosphazene chemistries for advanced materials applications

    NASA Astrophysics Data System (ADS)

    Hindenlang, Mark D.

    The work described within this thesis focuses on the design, synthesis, and characterization of new phosphazenes with potential in advanced materials applications. Additionally, these unique polymers required the development of novel reaction methods or the investigation of new phosphazene chemistry to achieve their synthesis. Chapter 1 lays out some of the basic principles and fundamentals of polymer chemistry. Chapter 2 investigates the use of iodinated polyphosphazenes as x-ray opaque materials. Single-substituent polymers with 4-iodophenoxy or 4-iodophenylanaline ethyl ester units as the only side groups were prepared. Although a single-substitutent polymer with 3,5-diiodotyrosine ethyl ester groups was difficult to synthesize, probably because of steric hindrance, mixed-substituent polymers that contained the non-iodinated ethyl esters of glycyine, alanine, or phenylalanine plus a corresponding iodinated substituent, could be synthesized. Multinuclear NMR spectroscopy was used to follow the substitution of side groups onto the phosphazene back bone and judge the ratio of substituents. Chapter 3 details the initial investigation into 3,4-dihydroxy-L-phenylalanine ethyl ester and dopamine substituted polyphosphazenes that could be applied to a number of applications. L-DOPAEE was acetonide protected to prevent crosslinking reactions by the catechole functionality. Cyclic small molecule studies and macromolecular substitution reactions on the linear high polymer were conducted with the protected L-DOPA. Continuing studies into protection of the dopamine catechol have elucidated a viable method for the synthesis of amino-linked dopamine polymers. Chapter 4 describes a method for the synthesis of phosphazenes with quaternary amine complexes as potential antibacterial agents. Replacement reactions of pyridine alkoxides and chlorophosphazenes were first attempted at the small molecule level to study the reactivities of pyridine alkoxides. The formation of an

  19. Radiation hardness by design for mixed signal infrared readout circuit applications

    NASA Astrophysics Data System (ADS)

    Gaalema, Stephen; Gates, James; Dobyns, David; Pauls, Greg; Wall, Bruce

    2013-09-01

    Readout integrated circuits (ROICs) to support space-based infrared detection applications often have severe radiation tolerance requirements. Radiation hardness-by-design (RHBD) significantly enhances the radiation tolerance of commercially available CMOS and custom radiation hardened fabrication techniques are not required. The combination of application specific design techniques, enclosed gate architecture nFETs and intrinsic thin oxide radiation hardness of 180 nm process node commercial CMOS allows realization of high performance mixed signal circuits. Black Forest Engineering has used RHBD techniques to develop ROICs with integrated A/D conversion that operate over a wide range of temperatures (40K-300K) to support infrared detection. ROIC radiation tolerance capability for 256x256 LWIR area arrays and 1x128 thermopile linear arrays is presented. The use of 130 nm CMOS for future ROIC RHBD applications is discussed.

  20. Applications of amorphous track models in radiation biology

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Nikjoo, H.; Goodhead, D. T.; Wilson, J. W. (Principal Investigator)

    1999-01-01

    The average or amorphous track model uses the response of a system to gamma-rays and the radial distribution of dose about an ion's path to describe survival and other cellular endpoints from proton, heavy ion, and neutron irradiation. This model has been used for over 30 years to successfully fit many radiobiology data sets. We review several extensions of this approach that address objections to the original model, and consider applications of interest in radiobiology and space radiation risk assessment. In the light of present views of important cellular targets, the role of target size as manifested through the relative contributions from ion-kill (intra-track) and gamma-kill (inter-track) remains a critical question in understanding the success of the amorphous track model. Several variations of the amorphous model are discussed, including ones that consider the radial distribution of event-sizes rather than average electron dose, damage clusters rather than multiple targets, and a role for repair or damage processing.

  1. Application of Computers for Experiment Design, Data Acquisition, and Analysis in the Chemistry Laboratory

    DTIC Science & Technology

    1990-05-01

    Computers have found many roles in the teaching of chemistry over the years. The role of the computer can be split into two general categories: review and...tutorial programs are used as a step-by-step method of teaching about chemical concepts. For example, a gas law tutorial may begin by presenting written...quality of tutorial software has made it a viable option for teaching and learning chemistry in almost any school. In almost every chemistry

  2. Open, Cross Platform Chemistry Application Unifying Structure Manipulation, External Tools, Databases and Visualization

    DTIC Science & Technology

    2014-05-30

    Figure 3. Several key resources have been put in place for the projects: • Community website dedicated to Open Chemistry projects • Git source code ...an open source project for the Android operating system, enables online review of code submissions from anyone while retaining control of what code is...chemistry community. The three Open Chemistry appli- cations (MongoChem, MoleQueue, and Avogadro 2) are available in both source and binary form for

  3. Remote radiation sensing module based on a silicon photomultiplier for industrial applications.

    PubMed

    Park, Hye Min; Joo, Koan Sik

    2016-09-01

    We have designed a silicon-photomultiplier-based remote radiation-sensing module consisting of a master port (displaying radiation information) and a slave port (detects radiation, transmits to master). The master port merges radiation and dose values and displays them. Counting detection efficiency and radiation response simulated using MCNPX were used to calibrate the module. We performed radioactive source tests ((137)Cs, (22)Na, (60)Co, (55)Fe) and compared experimental and simulation results. Remote detection capability was demonstrated and the detection accuracy was determined. Applications abound in the radioactivity industry.

  4. An intermetallic forming steel under radiation for nuclear applications

    NASA Astrophysics Data System (ADS)

    Hofer, C.; Stergar, E.; Maloy, S. A.; Wang, Y. Q.; Hosemann, P.

    2015-03-01

    In this work we investigated the formation and stability of intermetallics formed in a maraging steel PH 13-8 Mo under proton radiation up to 2 dpa utilizing nanoindentation, microcompression testing and atom probe tomography. A comprehensive discussion analyzing the findings utilizing rate theory is introduced, comparing the aging process to radiation induced diffusion. New findings of radiation induced segregation of undersize solute atoms (Si) towards the precipitates are considered.

  5. Application of ray tracing in radiation heat transfer

    NASA Technical Reports Server (NTRS)

    Baumeister, Joseph F.

    1993-01-01

    This collection of presentation figures displays the capabilities of ray tracing for radiation propagation calculations as compared to an analytical approach. The goal is to introduce the terminology and solution process used in ray tracing, and provide insight into radiation heat transfer principles and analysis tools. A thermal analysis working environment is introduced that solves demanding radiation heat transfer problems based on ray tracing. This information may serve as a reference for designing and building ones own analysis environment.

  6. The application of Synchrotron radiation based microtomography in (structural) geology

    NASA Astrophysics Data System (ADS)

    Fusseis, F.; Xiao, X.; Schrank, C.; Liu, J.; De Carlo, F.

    2012-04-01

    Synchrotron radiation based tomography (SRT) is a well established, yet still improving technique to image the internal microstructure of a wide range of materials in three dimensions. It benefits from the very high photon flux provided by synchrotron sources, which is collimated in a very small, coherent photon beam covering a continuous energy spectrum of up to 100 keV. Imaging techniques such as absorption contrast, absorption edge and phase contrast tomography as well as automated sample loading render the method very flexible for addressing a large number of scientific questions concerning rock microstructure. With different end stations for micro- and nanotomography achieving spatial resolutions of several hundred down to a few tens of nanometers, SRT provides three-dimensional microstructural data that bridge a critical gap towards the nanoscale. In combination with high-speed cameras even dense rock samples can be imaged in fractions of seconds, leading the way to time-resolved studies in 3D. Beyond the stunning three-dimensional insights that SRT data provide into rock microstructure, such data allow a quantitative and time-dependent characterisation of rock properties. On the way to such a characterisation, the quantitative analyses of three- and four-dimensional SRT data may pose a significant challenge for the user. The analyses are demanding in terms of the necessary hardware and software, and the procedure involves a number of possible technical pitfalls and analytical error sources. However, mastering these challenges means opening a new approach to experimental as well as computational rock mechanics and microstructural geology. Increasingly, these approaches are included in the multi-scale characterisation of rocks and their mechanical properties. This presentation aims at reviewing the potential of Synchrotron radiation based microtomography for research applications in structural geology and experimental rock mechanics. Besides outlining the

  7. Application of Monte Carlo methods in tomotherapy and radiation biophysics

    NASA Astrophysics Data System (ADS)

    Hsiao, Ya-Yun

    Helical tomotherapy is an attractive treatment for cancer therapy because highly conformal dose distributions can be achieved while the on-board megavoltage CT provides simultaneous images for accurate patient positioning. The convolution/superposition (C/S) dose calculation methods typically used for Tomotherapy treatment planning may overestimate skin (superficial) doses by 3-13%. Although more accurate than C/S methods, Monte Carlo (MC) simulations are too slow for routine clinical treatment planning. However, the computational requirements of MC can be reduced by developing a source model for the parts of the accelerator that do not change from patient to patient. This source model then becomes the starting point for additional simulations of the penetration of radiation through patient. In the first section of this dissertation, a source model for a helical tomotherapy is constructed by condensing information from MC simulations into series of analytical formulas. The MC calculated percentage depth dose and beam profiles computed using the source model agree within 2% of measurements for a wide range of field sizes, which suggests that the proposed source model provides an adequate representation of the tomotherapy head for dose calculations. Monte Carlo methods are a versatile technique for simulating many physical, chemical and biological processes. In the second major of this thesis, a new methodology is developed to simulate of the induction of DNA damage by low-energy photons. First, the PENELOPE Monte Carlo radiation transport code is used to estimate the spectrum of initial electrons produced by photons. The initial spectrum of electrons are then combined with DNA damage yields for monoenergetic electrons from the fast Monte Carlo damage simulation (MCDS) developed earlier by Semenenko and Stewart (Purdue University). Single- and double-strand break yields predicted by the proposed methodology are in good agreement (1%) with the results of published

  8. Fast All-Sky Radiation Model for Solar Applications (FARMS): A Brief Overview of Mechanisms, Performance, and Applications: Preprint

    SciTech Connect

    Xie, Yu; Sengupta, Manajit

    2016-06-01

    Solar radiation can be computed using radiative transfer models, such as the Rapid Radiation Transfer Model (RRTM) and its general circulation model applications, and used for various energy applications. Due to the complexity of computing radiation fields in aerosol and cloudy atmospheres, simulating solar radiation can be extremely time-consuming, but many approximations--e.g., the two-stream approach and the delta-M truncation scheme--can be utilized. To provide a new fast option for computing solar radiation, we developed the Fast All-sky Radiation Model for Solar applications (FARMS) by parameterizing the simulated diffuse horizontal irradiance and direct normal irradiance for cloudy conditions from the RRTM runs using a 16-stream discrete ordinates radiative transfer method. The solar irradiance at the surface was simulated by combining the cloud irradiance parameterizations with a fast clear-sky model, REST2. To understand the accuracy and efficiency of the newly developed fast model, we analyzed FARMS runs using cloud optical and microphysical properties retrieved using GOES data from 2009-2012. The global horizontal irradiance for cloudy conditions was simulated using FARMS and RRTM for global circulation modeling with a two-stream approximation and compared to measurements taken from the U.S. Department of Energy's Atmospheric Radiation Measurement Climate Research Facility Southern Great Plains site. Our results indicate that the accuracy of FARMS is comparable to or better than the two-stream approach; however, FARMS is approximately 400 times more efficient because it does not explicitly solve the radiative transfer equation for each individual cloud condition. Radiative transfer model runs are computationally expensive, but this model is promising for broad applications in solar resource assessment and forecasting. It is currently being used in the National Solar Radiation Database, which is publicly available from the National Renewable Energy

  9. “Modeling Trends in Aerosol Direct Radiative Effects over the Northern Hemisphere using a Coupled Meteorology-Chemistry Model”

    EPA Science Inventory

    While aerosol radiative effects have been recognized as some of the largest sources of uncertainty among the forcers of climate change, the verification of the spatial and temporal variability of the magnitude and directionality of aerosol radiative forcing has remained challengi...

  10. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1983

    1983-01-01

    Presents chemistry experiments, laboratory procedures, demonstrations, and classroom materials/activities. These include: experiments on colloids, processing of uranium ore, action of heat on carbonates; color test for phenols and aromatic amines; solvent properties of non-electrolytes; stereoscopic applications/methods; a valency balance;…

  11. Radiation Transport Tools for Space Applications: A Review

    NASA Technical Reports Server (NTRS)

    Jun, Insoo; Evans, Robin; Cherng, Michael; Kang, Shawn

    2008-01-01

    This slide presentation contains a brief discussion of nuclear transport codes widely used in the space radiation community for shielding and scientific analyses. Seven radiation transport codes that are addressed. The two general methods (i.e., Monte Carlo Method, and the Deterministic Method) are briefly reviewed.

  12. The effects of a technology-driven science application on postsecondary chemistry student achievement and self-efficacy

    NASA Astrophysics Data System (ADS)

    Byrum, Darrell Scott

    The purpose of this study was to establish if distinction exists in both student achievement and self-efficacy through the application of technology-based instructional approach in the laboratory environment of undergraduate chemistry courses. The achievement of 52 college students in the southeastern region of the United States was measured through one posttest assessment. Following this assessment, students were examined through a self-efficacy scale to determine preexisting thoughts of working in an undergraduate chemistry laboratory environment, as well as peer interaction. Accordingly, three separate college chemistry I courses were used to generate data via a nonequivalent control group design. From the three courses, one class was labeled as the treatment group, while the two remaining classes were collectively labeled as the control group. The treatment group was made up of 22 participants, while the control group was comprised of 30 participants. Students in both the control and treatment groups completed the same laboratory experiments; however, the control group used traditional methods for conducting the laboratory experiments while the treatment group implemented a technology-based approach. To measure achievement, data was gathered through the administration of the Conceptual Problems Gases Test (CPGT). Self-efficacy was measured through the College Chemistry Self-Efficacy Scale (CCSS). Results from both instruments were shown through independent samples t-tests; furthermore, as reflected by p values, the technology-driven application did not have a statistically significant difference on student achievement.

  13. A Comprehensive Study of Surface Chemistry for Application to Engine NOx Aftertreatment

    SciTech Connect

    Aceves, S M; Piggot, T; Pitz, W; Mundy, C; Kuo, W; Havstad, M

    2004-02-19

    This work focuses on developing a scientific understanding of the processes associated with NO{sub x} trap operation. NO{sub x} traps are the most advanced technology for achieving future emissions standards with diesel engines. Successful development of NO{sub x} traps will allow widespread use of diesel engines in light-duty vehicles, reducing oil imports by as much as 60%. Diesel engines have a high efficiency and low maintenance that makes them the ideal choice for transportation applications. Use of diesel engines in all light-duty vehicles would reduce oil consumption in the USA by 30% and oil imports by 60%, considerably improving our energy security. For heavy trucks, there is no viable alternative to diesel engines. Only diesel engines can provide the necessary high efficiency and long life. These benefits are offset by high emission of pollutants. Diesel engines have high emissions of NO{sub x} and particulate matter. Over the last 20 years, EPA has been reducing allowable emissions from diesel engines, and NO{sub x} emissions are scheduled to be cut by a factor of 10 over the next 7 years. The target NO{sub x} emissions for year 2010 is 0.20 g/hp-hr. This value is well below 1 g/hp-hr, which has been identified by one of the authors (Pitz [1]) as the minimum possible NO{sub x} emissions that can be obtained in a diesel engine with satisfactory combustion and without exhaust aftertreatment. An 80% efficient aftertreatment system is therefore necessary for achieving the 2010 NO{sub x} emissions regulation. Achieving this level of diesel aftertreatment efficiency is a daunting task, and one that will require a strong research effort. Manufacturing diesel after treatment systems with 80% efficiency for model year 2010 is an extremely difficult task. Our advanced analysis tools (computational chemistry linked with fluid mechanics and heat transfer) can be used to analyze and optimize NO{sub x} traps, which are the system of choice for diesel engine

  14. Balancing Chemical Reactions With Matrix Methods and Computer Assistance. Applications of Linear Algebra to Chemistry. Modules and Monographs in Undergraduate Mathematics and Its Applications Project. UMAP Unit 339.

    ERIC Educational Resources Information Center

    Grimaldi, Ralph P.

    This material was developed to provide an application of matrix mathematics in chemistry, and to show the concepts of linear independence and dependence in vector spaces of dimensions greater than three in a concrete setting. The techniques presented are not intended to be considered as replacements for such chemical methods as oxidation-reduction…

  15. Integrative Biological Chemistry Program Includes the Use of Informatics Tools, GIS and SAS Software Applications

    ERIC Educational Resources Information Center

    D'Souza, Malcolm J.; Kashmar, Richard J.; Hurst, Kent; Fiedler, Frank; Gross, Catherine E.; Deol, Jasbir K.; Wilson, Alora

    2015-01-01

    Wesley College is a private, primarily undergraduate minority-serving institution located in the historic district of Dover, Delaware (DE). The College recently revised its baccalaureate biological chemistry program requirements to include a one-semester Physical Chemistry for the Life Sciences course and project-based experiential learning…

  16. Refinement, Application, and Evaluation of Cognitive and Affective Chemistry Measures for College Students

    ERIC Educational Resources Information Center

    Heredia, Keily

    2013-01-01

    This work describes three case studies conducted to address two major problems in the area of chemistry education research, the lack of reported psychometrics regarding instrument scores, and the need for well-characterized assessments to evaluate college chemistry curricula. The first case study describes a psychometric evaluation of the Colorado…

  17. Liquid phase thermochemical energy conversion systems - An application of Diels-Alder chemistry

    NASA Astrophysics Data System (ADS)

    Lenz, T. G.; Hegedus, L. S.; Vaughan, J. D.

    1982-12-01

    A method of thermochemical energy conversion, transport, and storage research involving moderate and low temperature liquid phase systems employing Diels-Alder cycloaddition chemistry is described. Proposed as a heat storage system for solar and industrial waste heat, the system involves the meeting, in a reactor, of energy-depleted and energy-rich fluids. The poor fluid gains energy and goes through a chemical, endothermic dissociative change. The use of Diels-Alder reactions provides completely reversible chemical reactions for this application. The heated fluid can be retransported for storage or implementation as a heat source. The return reaction, releasing the stored heat, can be done spontaneously or in the presence of a catalyst such as Lewis acids. Attention is recommended for the Wentworth-Chen temperature of 250-300 C to minimize the system thermal degradation. Research in the synthesis of diene and dienophile candidate chemicals, into sealed tube and reaction kinetic techniques, and into NMR techniques for identifying further reaction candidates are discussed.

  18. Synthesis, properties, and application in peptide chemistry of a magnetically separable and reusable biocatalyst

    NASA Astrophysics Data System (ADS)

    Liria, Cleber W.; Ungaro, Vitor A.; Fernandes, Raphaella M.; Costa, Natália J. S.; Marana, Sandro R.; Rossi, Liane M.; Machini, M. Teresa

    2014-11-01

    Enzyme-catalyzed chemical processes are selective, very productive, and generate little waste. Nevertheless, they may be optimized using enzymes bound to solid supports, which are particularly important for protease-mediated reactions since proteases undergo fast autolysis in solution. Magnetic nanoparticles are suitable supports for this purpose owing to their high specific surface area and to be easily separated from reaction media. Here we describe the immobilization of bovine α-chymotrypsin (αCT) on silica-coated superparamagnetic nanoparticles (Fe3O4@silica) and the characterization of the enzyme-nanoparticle hybrid (Fe3O4@silica-αCT) in terms of protein content, properties, recovery from reaction media, application, and reuse in enzyme-catalyzed peptide synthesis. The results revealed that (i) full acid hydrolysis of the immobilized protease followed by amino acid analysis of the hydrolyzate is a reliable method to determine immobilization yield; (ii) despite showing lower amidase activity and a lower K cat/ K m value for a specific substrate than free αCT, the immobilized enzyme is chemically and thermally more stable, magnetically recoverable from reaction media, and can be consecutively reused for ten cycles to catalyze the amide bond hydrolysis and ester hydrolysis of the protected dipeptide Z-Ala-Phe-OMe. Altogether, these properties indicate the potential of Fe3O4@silica-αCT to act as an efficient, suitably stable, and reusable catalyst in amino acid, peptide, and protein chemistry as well as in proteomic studies.

  19. Hydrogen Sulfide (H2S) Releasing Agents: Chemistry and Biological Applications

    PubMed Central

    Zhao, Yu; Biggs, Tyler D.

    2014-01-01

    Hydrogen sulfide (H2S) is a newly recognized signaling molecule with very potent cytoprotective actions. The fields of H2S physiology and pharmacology have been rapidly growing in recent years, but a number of fundamental issues must be addressed to advance our understanding of the biology and clinical potential of H2S in the future. Hydrogen sulfide releasing agents (also known as H2S donors) have been widely used in the field. These compounds are not only useful research tools, but also potential therapeutic agents. It is therefore important to study the chemistry and pharmacology of exogenous H2S and to be aware of the limitations associated with the choice of donors used to generate H2S in vitro and in vivo. In this review we summarized the developments and limitations of current available donors including H2S gas, sulfide salts, garlic-derived sulfur compounds, Lawesson’s reagent/analogs, 1,2-dithiole-3-thiones, thiol-activated donors, photo-caged donors, and thioamino acids. Some biological applications of these donors were also discussed. PMID:25019301

  20. The nucleation rate surfaces design over diagram of phase equilibria and their applications for computational chemistry

    NASA Astrophysics Data System (ADS)

    Anisimov, M. P.

    2016-12-01

    One can find in scientific literature a pretty fresh idea of the nucleation rate surfaces design over the diagrams of phase equilibria. That idea looks like profitable for the nucleation theory development and for various practical applications where predictions of theory have no high enough accuracy for today. The common thermodynamics has no real ability to predict parameters of the first order phase transition. Nucleation experiment can be provided in very local nucleation conditions even the nucleation takes place from the critical line (in two-component case) down to the absolute zero temperature limit and from zero nucleation rates at phase equilibria up to the spinodal conditions. Theory predictions have low reliability as a rule. The computational chemistry has chance to make solution of that problem easier when a set of the used axiomatic statements will adapt enough progressive assumptions [1]. Semiempirical design of the nucleation rate surfaces over diagrams of phase equilibria have a potential ability to provide a reasonable quality information on nucleation rate for each channel of nucleation. Consideration and using of the nucleation rate surface topologies to optimize synthesis of a given phase of the target material can be available when data base on nucleation rates over diagrams of phase equilibria will be created.

  1. Direct Radiative Forcing and Regional Climatic Effects of Anthropogenic Aerosols Over East Asia: A Regional Coupled Climate-Chemistry/Aerosol Model Study

    SciTech Connect

    Giorgi, Filippo; Bi, Xunqiang; Qian, Yun )

    2002-09-01

    We present a series of regional climate model simulations aimed at assessing the radiative forcing and surface climatic effects of anthropogenic sulfate and fossil fuel soot over east Asia. The simulations are carried out with a coupled regional climate-chemistry/aerosol model for the 5-year period of 1993-1997 using published estimates of sulfur emissions for the period. Anthropogenic sulfate induces a negative radiative forcing spatially varying from -1 to -8 W/m2 in the winter to -1 to -15 W/m2 in the summer, with maxima over the Sichan Basin of southwest China and over some areas of east and northeast China. This forcing induces a surface cooling in the range of -0.1 to -0.7 K. Fossil fuel soot exerts a positive atmospheric radiative forcing of 0.5 to 2 W/m2 and enhances the surface cooling by a few tenths of K due to increased surface shielding from solar radiation. Doubling of sulfur emissions induces a substantial increase in radiative forcing (up to -7 to -8 W/m2) and associated surface cooling. With doubled sulfur emissions, the surface cooling exceeds -1 K and is statistically significant at the 90% confidence level over various areas of China. The aerosol forcing and surface cooling tend to inhibit precipitation over the region, although this effect is relatively small in the simulations. Some features of the simulated aerosol-induced cooling are consistent with temperature trends observed in recent decades over different regions of China.

  2. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  3. Application of Stochastic Radiative Transfer Theory to the ARM Cloud-Radiative Parameterization Problem

    SciTech Connect

    Veron, Dana E

    2009-03-12

    This project had two primary goals: 1) development of stochastic radiative transfer as a parameterization that could be employed in an AGCM environment, and 2) exploration of the stochastic approach as a means for representing shortwave radiative transfer through mixed-phase layer clouds. To achieve these goals, an analysis of the performance of the stochastic approach was performed, a simple stochastic cloud-radiation parameterization for an AGCM was developed and tested, a statistical description of Arctic mixed phase clouds was developed and the appropriateness of stochastic approach for representing radiative transfer through mixed-phase clouds was assessed. Significant progress has been made in all of these areas and is detailed below.

  4. Application of Stochastic Radiative Transfer Theory to the ARM Cloud-Radiative Parameterization Problem

    SciTech Connect

    Dana E. Veron

    2012-04-09

    This project had two primary goals: (1) development of stochastic radiative transfer as a parameterization that could be employed in an AGCM environment, and (2) exploration of the stochastic approach as a means for representing shortwave radiative transfer through mixed-phase layer clouds. To achieve these goals, climatology of cloud properties was developed at the ARM CART sites, an analysis of the performance of the stochastic approach was performed, a simple stochastic cloud-radiation parameterization for an AGCM was developed and tested, a statistical description of Arctic mixed phase clouds was developed and the appropriateness of stochastic approach for representing radiative transfer through mixed-phase clouds was assessed. Significant progress has been made in all of these areas and is detailed in the final report.

  5. The Application of FLUKA to Dosimetry and Radiation Therapy

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L.; Andersen, Victor; Pinsky, Lawrence; Ferrari, Alfredo; Battistoni, Giusenni

    2005-01-01

    Monte Carlo transport codes like FLUKA are useful for many purposes, and one of those is the simulation of the effects of radiation traversing the human body. In particular, radiation has been used in cancer therapy for a long time, and recently this has been extended to include heavy ion particle beams. The advent of this particular type of therapy has led to the need for increased capabilities in the transport codes used to simulate the detailed nature of the treatment doses to the Y O U S tissues that are encountered. This capability is also of interest to NASA because of the nature of the radiation environment in space.[l] While in space, the crew members bodies are continually being traversed by virtually all forms of radiation. In assessing the risk that this exposure causes, heavy ions are of primary importance. These arise both from the primary external space radiation itself, as well as fragments that result from interactions during the traversal of that radiation through any intervening material including intervening body tissue itself. Thus the capability to characterize the details of the radiation field accurately within a human body subjected to such external 'beams" is of critical importance.

  6. APPLICATION OF INFRARED SPECTROSCOPY TO THE ANALYSIS OF INORGANIC NITRATES. PHASE 1. SPECTRA OF INORGANIC NITRATES IN ACETONE AND THE USE OF SUCH SPECTRA IN ANALYTICAL CHEMISTRY

    DTIC Science & Technology

    A study was made of the spectra of soluble inorganic nitrates in acetone solution and the use of such spectra in analytical chemistry . The spectra of...solubilities of anhydrous inorganic nitrates in acetone. The applications of the spectra of inorganic nitrates in acetone to analytical chemistry is

  7. New developments in theoretical thermochemistry and electronic structure applications in supramolecular chemistry and cluster science

    NASA Astrophysics Data System (ADS)

    Ramabhadran, Raghunath Ozhapakkam

    In a concise display of the power and diversity of electronic structure theory (EST), the work presented herein involves the development of new computational methods to advance the practical utility of quantum chemistry, as well as solving different types of challenging chemical problems by applying existing EST tools. The research presented is highly interdisciplinary in nature and features synergistic collaborations to solve real-life problems such as regulating toxic chemicals and generating alternative sources of energy. In the first chapter of this dissertation, the solution to a long-standing problem in theoretical thermochemistry is accomplished by the development of the automated, chemically intuitive and generalized thermochemical hierarchy, Connectivity-Based Hierarchy (CBH) to accurately predict the thermochemical properties of organic molecules. The extension of the hierarchy to predict the enthalpies of formations of biomonomers such as amino acids is also presented. The development of a computationally efficient protocol to accurately extrapolate to high CCSD(T) energies based on MP2 and DFT energies using CBH is presented in the second chapter, thus merging theoretical thermochemistry with fragment-based methods in quantum chemistry. This merger drastically reduces the computational cost involved in a CCSD(T) calculation, while retaining the impeccable accuracy it offers. The practical utility of the CH hydrogen bond, commonly thought as being too weak to be used in supramolecular applications has been demonstrated by DFT calculations (along with experimental results from the Flood group) in the third chapter. This is accomplished by systematically studying the binding of monoatomic chloride, diatomic and toxic cyanide and the polyatomic bi-fluoride anions for the first time using only CH hydrogen bonds within a triazolophane macrocycle. The fourth chapter contains the introduction of the concept of fluxionality in the chemical reactions of

  8. Moderate Image Spectrometer (MODIS) Fire Radiative Energy: Physics and Applications

    NASA Technical Reports Server (NTRS)

    Kaufman, Y.

    2004-01-01

    MODIS fire channel does not saturate in the presence of fires. The fire channel therefore is used to estimate the fire radiative energy, a measure of the rate of biomass consumption in the fire. We found correlation between the fire radiative energy, the rate of formation of burn scars and the rate of emission of aerosol from the fires. Others found correlations between the fire radiative energy and the rate of biomass consumption. This relationships can be used to estimates the emissions from the fires and to estimate the fire hazards.

  9. Acceptability of risk from radiation: Application to human space flight

    SciTech Connect

    1997-04-30

    This one of NASA`s sponsored activities of the NCRP. In 1983, NASA asked NCRP to examine radiation risks in space and to make recommendations about career radiation limits for astronauts (with cancer considered as the principal risk). In conjunction with that effort, NCRP was asked to convene this symposium; objective is to examine the technical, strategic, and philosophical issues pertaining to acceptable risk and radiation in space. Nine papers are included together with panel discussions and a summary. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  10. Radiological protection, safety and security issues in the industrial and medical applications of radiation sources

    NASA Astrophysics Data System (ADS)

    Vaz, Pedro

    2015-11-01

    The use of radiation sources, namely radioactive sealed or unsealed sources and particle accelerators and beams is ubiquitous in the industrial and medical applications of ionizing radiation. Besides radiological protection of the workers, members of the public and patients in routine situations, the use of radiation sources involves several aspects associated to the mitigation of radiological or nuclear accidents and associated emergency situations. On the other hand, during the last decade security issues became burning issues due to the potential malevolent uses of radioactive sources for the perpetration of terrorist acts using RDD (Radiological Dispersal Devices), RED (Radiation Exposure Devices) or IND (Improvised Nuclear Devices). A stringent set of international legally and non-legally binding instruments, regulations, conventions and treaties regulate nowadays the use of radioactive sources. In this paper, a review of the radiological protection issues associated to the use of radiation sources in the industrial and medical applications of ionizing radiation is performed. The associated radiation safety issues and the prevention and mitigation of incidents and accidents are discussed. A comprehensive discussion of the security issues associated to the global use of radiation sources for the aforementioned applications and the inherent radiation detection requirements will be presented. Scientific, technical, legal, ethical, socio-economic issues are put forward and discussed.

  11. Impact of UV-A radiation on the performance of aphids and whiteflies and on the leaf chemistry of their host plants.

    PubMed

    Dáder, Beatriz; Gwynn-Jones, Dylan; Moreno, Aránzazu; Winters, Ana; Fereres, Alberto

    2014-09-05

    Ultraviolet (UV) radiation directly regulates a multitude of herbivore life processes, in addition to indirectly affecting insect success via changes in plant chemistry and morphogenesis. Here we looked at plant and insect (aphid and whitefly) exposure to supplemental UV-A radiation in the glasshouse environment and investigated effects on insect population growth. Glasshouse grown peppers and eggplants were grown from seed inside cages covered by novel plastic filters, one transparent and the other opaque to UV-A radiation. At a 10-true leaf stage for peppers (53 days) and 4-true leaf stage for eggplants (34 days), plants were harvested for chemical analysis and infested by aphids and whiteflies, respectively. Clip-cages were used to introduce and monitor the insect fitness and populations of the pests studied. Insect pre-reproductive period, fecundity, fertility and intrinsic rate of natural increase were assessed. Crop growth was monitored weekly for 7 and 12 weeks throughout the crop cycle of peppers and eggplants, respectively. At the end of the insect fitness experiment, plants were harvested (68 days and 18-true leaf stage for peppers, and 104 days and 12-true leaf stage for eggplants) and leaves analysed for secondary metabolites, soluble carbohydrates, amino acids, total proteins and photosynthetic pigments. Our results demonstrate for the first time, that UV-A modulates plant chemistry with implications for insect pests. Both plant species responded directly to UV-A by producing shorter stems but this effect was only significant in pepper whilst UV-A did not affect the leaf area of either species. Importantly, in pepper, the UV-A treated plants contained higher contents of secondary metabolites, leaf soluble carbohydrates, free amino acids and total content of protein. Such changes in tissue chemistry may have indirectly promoted aphid performance. For eggplants, chlorophylls a and b, and carotenoid levels decreased with supplemental UV-A over the entire

  12. Recent status on cobalt-60 gamma ray radiation sources production and its application in China

    NASA Astrophysics Data System (ADS)

    Zhijian, Cao; Yunjiang, Song; Chunchua, Zhang; Maoling, Li

    1993-07-01

    This paper describes the recent status on Co-60 γ ray radiation sources production and its application in China. At present, the production capacity of Co-60 γ ray radiation sources in China is about 11.1 PBq(0.3 MCi) per year, 5 years later, it can increase to 37 PBq(1 MCi) per year. The standard dimension of Co-60 γ ray radiation sources is φ 15×90 mm, the radioactivity of each sources is 370TBq - 740TBq(1000-2000 Ci). There are over 150 Co-60 γ ray radiation facilities with total design capacity of over 370 PBq(10 MCi) and practical capacity of about 92.5 PBq(2.5 MCi) in operation. The number of Co-60 γ ray radiation facilities with practical capacity of over 3.7 PBq(0.1 MCi) is 14. The main applications of the Co-60 γ ray sources are radiation crosslinking application, radiation sterilization of disposable medical supplies and food irradiation. The prospect of Co-60 γ ray radiation sources production and its application in China is good.

  13. Some new results on irradiation characteristics of synthetic quartz crystals and their application to radiation hardening

    NASA Technical Reports Server (NTRS)

    Bahadur, H.; Parshad, R.

    1983-01-01

    The paper reports some new results on irradiation characteristics of synthetic quartz crystals and their application to radiation hardening. The present results show how the frequency shift in quartz crystals can be influenced by heat processing prior to irradiation and how this procedure can lead to radiation hardening for obtaining precise frequencies and time intervals from quartz oscillators in space.

  14. Modeling molecular computing systems by an artificial chemistry - its expressive power and application.

    PubMed

    Tominaga, Kazuto; Watanabe, Tooru; Kobayashi, Keiji; Nakamura, Masaki; Kishi, Koji; Kazuno, Mitsuyoshi

    2007-01-01

    Artificial chemistries are mainly used to construct virtual systems that are expected to show behavior similar to living systems. In this study, we explore possibilities of applying an artificial chemistry to modeling natural biochemical systems-or, to be specific, molecular computing systems-and show that it may be a useful modeling tool for molecular computation. We previously proposed an artificial chemistry based on string pattern matching and recombination. This article first demonstrates that this artificial chemistry is computationally universal if it has only rules that have one reactant or two reactants. We think this is a good property of an artificial chemistry that models molecular computing, because natural elementary chemical reactions, on which molecular computing is based, are mostly unimolecular or bimolecular. Then we give two illustrative example models for DNA computing in our artificial chemistry: one is for the type of computation called the Adleman-Lipton paradigm, and the other is for a DNA implementation of a finite automaton. Through the construction of these models we observe preferred properties of the artificial chemistry for modeling molecular computing, such as having no spatial structure and being flexible in choosing levels of abstraction.

  15. Carbon Nanotube Reinforced Polymers for Radiation Shielding Applications

    NASA Technical Reports Server (NTRS)

    Thibeault, S. (Technical Monitor); Vaidyanathan, Ranji

    2004-01-01

    This viewgraph presentation provides information on the use of Extrusion Freeform Fabrication (EEF) for the fabrication of carbon nanotubes. The presentation addresses TGA analysis, Raman spectroscopy, radiation tests, and mechanical properties of the carbon nanotubes.

  16. Far infrared radiation (FIR): its biological effects and medical applications

    PubMed Central

    Vatansever, Fatma; Hamblin, Michael R.

    2013-01-01

    Far infrared (FIR) radiation (λ = 3–100 μm) is a subdivision of the electromagnetic spectrum that has been investigated for biological effects. The goal of this review is to cover the use of a further sub-division (3– 12 μm) of this waveband, that has been observed in both in vitro and in vivo studies, to stimulate cells and tissue, and is considered a promising treatment modality for certain medical conditions. Technological advances have provided new techniques for delivering FIR radiation to the human body. Specialty lamps and saunas, delivering pure FIR radiation (eliminating completely the near and mid infrared bands), have became safe, effective, and widely used sources to generate therapeutic effects. Fibers impregnated with FIR emitting ceramic nanoparticles and woven into fabrics, are being used as garments and wraps to generate FIR radiation, and attain health benefits from its effects. PMID:23833705

  17. Far infrared radiation (FIR): its biological effects and medical applications.

    PubMed

    Vatansever, Fatma; Hamblin, Michael R

    2012-11-01

    Far infrared (FIR) radiation (λ = 3-100 μm) is a subdivision of the electromagnetic spectrum that has been investigated for biological effects. The goal of this review is to cover the use of a further sub-division (3- 12 μm) of this waveband, that has been observed in both in vitro and in vivo studies, to stimulate cells and tissue, and is considered a promising treatment modality for certain medical conditions. Technological advances have provided new techniques for delivering FIR radiation to the human body. Specialty lamps and saunas, delivering pure FIR radiation (eliminating completely the near and mid infrared bands), have became safe, effective, and widely used sources to generate therapeutic effects. Fibers impregnated with FIR emitting ceramic nanoparticles and woven into fabrics, are being used as garments and wraps to generate FIR radiation, and attain health benefits from its effects.

  18. Polyethylene/Boron Composites for Radiation Shielding Applications

    SciTech Connect

    Harrison, Courtney; Grulke, Eric; Burgett, Eric; Hertel, Nolan

    2008-01-21

    Multifunctional composites made with boron are absorbers of low energy nuetrons, and could be used for structural shielding materials. Polyethylene/boron carbide composites were fabricated using conventional polymer processing techniques, and were evaluated for mechanical and radiation shielding properties. Addition of neat boron carbide (powder and nanoparticles) to an injection molding grade HPDE showed superior mechanical properties compared to neat HDPE. Radiation shielding measurements of a 2 wt% boron carbide composite were improved over those of the neat polyethylene.

  19. Technical note: application of α-QSS to the numerical integration of kinetic equations in tropospheric chemistry

    NASA Astrophysics Data System (ADS)

    Liu, F.; Schaller, E.; Mott, D. R.

    2005-08-01

    A major task in many applications of atmospheric chemistry transport problems is the numerical integration of stiff systems of Ordinary Differential Equations (ODEs) describing the chemical transformations. A faster solver that is easier to couple to the other physics in the problem is still needed. The integration method, α-QSS, corresponding to the solver CHEMEQ2 aims at meeting the demands of a process-split, reacting-flow simulation (Mott 2000; Mott and Oran, 2001). However, this integrator has yet to be applied to the numerical integration of kinetic equations in tropospheric chemistry. A zero-dimensional (box) model is developed to test how well CHEMEQ2 works on the tropospheric chemistry equations. This paper presents the testing results. The reference chemical mechanisms herein used are Regional Atmospheric Chemistry Mechanism (RACM) (Stockwell et al., 1997) and its secondary lumped successor Regional Lumped Atmospheric Chemical Scheme (ReLACS) (Crassier et al., 2000). The box model is forced and initialized by the DRY scenarios of Protocol Ver. 2 developed by EUROTRAC (Poppe et al., 2001). The accuracy of CHEMEQ2 is evaluated by comparing the results to solutions obtained with VODE. This comparison is made with parameters of the error tolerance, relative difference with respect to VODE scheme, trade off between accuracy and efficiency, global time step for integration etc. The study based on the comparison concludes that the single-point α-QSS approach is fast and moderately accurate as well as easy to couple to reacting flow simulation models, which makes CHEMEQ2 one of the best candidates for three-dimensional atmospheric Chemistry Transport Modelling (CTM) studies. In addition the RACM mechanism may be replaced by ReLACS mechanism for tropospheric chemistry transport modelling. The testing results also imply that the accuracy for chemistry numerical simulations is highly different from species to species. Therefore ozone is not the good choice for

  20. Fervent: chemistry-coupled, ionizing and non-ionizing radiative feedback in hydrodynamical simulations

    NASA Astrophysics Data System (ADS)

    Baczynski, C.; Glover, S. C. O.; Klessen, R. S.

    2015-11-01

    We introduce a radiative transfer code module for the magnetohydrodynamical adaptive mesh refinement code FLASH 4. It is coupled to an efficient chemical network which explicitly tracks the three hydrogen species H, H2, H+ as well as C+ and CO. The module is geared towards modelling all relevant thermal feedback processes of massive stars, and is able to follow the non-equilibrium time-dependent thermal and chemical state of the present-day interstellar medium as well as that of dense molecular clouds. We describe in detail the implementation of all relevant thermal stellar feedback mechanisms, i.e. photoelectric, photoionization and H2 dissociation heating as well as pumping of molecular hydrogen by UV photons. All included radiative feedback processes are extensively tested. We also compare our module to dedicated photodissociation region (PDR) codes and find good agreement in our modelled hydrogen species once our radiative transfer solution reaches equilibrium. In addition, we show that the implemented radiative feedback physics is insensitive to the spatial resolution of the code and show under which conditions it is possible to obtain well-converged evolution in time. Finally, we briefly explore the robustness of our scheme for treating combined ionizing and non-ionizing radiation.

  1. Radiation hardening of components and systems for nuclear rocket vehicle applications

    NASA Technical Reports Server (NTRS)

    Greenhow, W. A.; Cheever, P. R.

    1972-01-01

    The results of the analysis of the S-2 and S-4B components, although incomplete, indicate that many Saturn 5 components and subsystems, e.g., pumps, valves, etc., can be radiation hardened to meet NRV requirements by material substitution and minor design modifications. Results of these analyses include (1) recommended radiation tolerance limits for over 100 material applications; (2) design data which describes the components of each system; (3) presentation of radiation hardening examples of systems; and (4) designing radiation effects tests to supply data for selecting materials.

  2. EFFECT OF BIOSOLIDS APPLICATION ON SOIL METAL CHEMISTRY AND PHYTOAVAILABILITY (LAKE BUENA VISTA, FL)

    EPA Science Inventory

    Addition of biosolids to soils increases the environmental loading of toxic metals (Cd, Zn, Cu, Ni, Pb, etc.) and alters the chemistry and phytoavailability of these metals. This alteration in phytoavailability associated with biosolids amended soil was recognized and utilized ...

  3. Application of Advances in Learning Theory and Philosophy of Science to the Improvement of Chemistry Teaching.

    ERIC Educational Resources Information Center

    Novak, Joseph D.

    1984-01-01

    Discusses seven key concepts in Ausubel's learning theory which function to guide research and teaching. Also discusses concept mapping and Gowins Vee, providing examples of how they are used in chemistry instruction. (JN)

  4. Application of Synchrotron Radiation in the Geological and Environmental Sciences

    SciTech Connect

    Jones, Keith W.

    1999-09-01

    A survey of some of the different ways that synchrotrons x-ray beams can be used to study geological materials is presented here. This field developed over a period of about 30 years, and it is clear that the geological community has made major use of the many synchrotrons facilities operating around the world during this time period. This was a time of rapid change in the operational performance of the synchrotrons facilities and this in itself has made it possible for geologists to develop new and more refined types of experiments that have yielded many important results. The advance in experimental techniques has proceeded in parallel with a revolution in computing techniques that has made it possible to cope with the great amount of data accumulated in the experiments. It is reasonable, although risky, to speculate about what might be expected to develop in the field during the next five- to ten-year period. It does seem plausible that the rate of change in the performance of what might now be called conventional x-ray storage rings will slow. There are no new facilities that are superior to the ESRF, ALS, APS, or SPring8 facilities under construction or about to come into operation. Thus, performance increments in the characteristics of the x-ray sources may come through the introduction of specialized devices in existing storage rings. The free electron laser is one example of a developing new technology that should take us into new regions of performance for radiation sources and stimulate new types of experimental applications. It is also likely that major advances will come through the introduction of more sophisticated experimental devices developed for use with the very recently operational undulator or wiggler sources at the newer rings. Improved x-ray optics and x-ray detectors and more powerful computation and high-speed data transmission can bring about more refined experiments and make the synchrotrons facilities more widely available to the

  5. Radiation

    NASA Video Gallery

    Outside the protective cocoon of Earth's atmosphere, the universe is full of harmful radiation. Astronauts who live and work in space are exposed not only to ultraviolet rays but also to space radi...

  6. The flow synthesis of heterocycles for natural product and medicinal chemistry applications.

    PubMed

    Baumann, Marcus; Baxendale, Ian R; Ley, Steven V

    2011-08-01

    This article represents an overview of recent research from the Innovative Technology Centre in the field of flow chemistry which was presented at the FROST2 meeting in Budapest in October 2009. After a short introduction of this rapidly expanding field, we discuss some of our results with a main focus on the synthesis of heterocyclic compounds which we use in various natural product and medicinal chemistry programmes.

  7. Development and validation of chemistry agnostic flow battery cost performance model and application to nonaqueous electrolyte systems: Chemistry agnostic flow battery cost performance model

    SciTech Connect

    Crawford, Alasdair; Thomsen, Edwin; Reed, David; Stephenson, David; Sprenkle, Vincent; Liu, Jun; Viswanathan, Vilayanur

    2016-04-20

    A chemistry agnostic cost performance model is described for a nonaqueous flow battery. The model predicts flow battery performance by estimating the active reaction zone thickness at each electrode as a function of current density, state of charge, and flow rate using measured data for electrode kinetics, electrolyte conductivity, and electrode-specific surface area. Validation of the model is conducted using a 4kW stack data at various current densities and flow rates. This model is used to estimate the performance of a nonaqueous flow battery with electrode and electrolyte properties used from the literature. The optimized cost for this system is estimated for various power and energy levels using component costs provided by vendors. The model allows optimization of design parameters such as electrode thickness, area, flow path design, and operating parameters such as power density, flow rate, and operating SOC range for various application duty cycles. A parametric analysis is done to identify components and electrode/electrolyte properties with the highest impact on system cost for various application durations. A pathway to 100$kWh-1 for the storage system is identified.

  8. Main principles of radiation protection and their applications in waste management

    SciTech Connect

    Devgun, J.S.

    1993-09-01

    The average exposure for an individual from such background in the United States is about 300 mrem per year with approximately 200 mrem of this coming from radon exposure alone. In addition to the natural sources of background radiation, a very small amount of the background radiation occurs due to the nuclear weapons test fallout. Manmade sources of radiation also include certain consumer products, industrial and research use of radioisotopes, medical X-rays, and radiopharmaceuticals. When all sources, natural and man-made, are taken into account, the National Council on Radiation Protection and Measurements (NCRP) has estimated that the average annual dose to individuals in the US population is 360 mrem (NCRP Report No. 93). In this report the fundamental principles of radiation protection are reviewed, as well as the relevant laws and regulations in the United States and discuss application of radiation protection in radioactive waste management.

  9. Application of Multivariate Modeling for Radiation Injury Assessment: A Proof of Concept

    PubMed Central

    Bolduc, David L.; Villa, Vilmar; Sandgren, David J.; Ledney, G. David; Blakely, William F.; Bünger, Rolf

    2014-01-01

    Multivariate radiation injury estimation algorithms were formulated for estimating severe hematopoietic acute radiation syndrome (H-ARS) injury (i.e., response category three or RC3) in a rhesus monkey total-body irradiation (TBI) model. Classical CBC and serum chemistry blood parameters were examined prior to irradiation (d 0) and on d 7, 10, 14, 21, and 25 after irradiation involving 24 nonhuman primates (NHP) (Macaca mulatta) given 6.5-Gy 60Co Υ-rays (0.4 Gy min−1) TBI. A correlation matrix was formulated with the RC3 severity level designated as the “dependent variable” and independent variables down selected based on their radioresponsiveness and relatively low multicollinearity using stepwise-linear regression analyses. Final candidate independent variables included CBC counts (absolute number of neutrophils, lymphocytes, and platelets) in formulating the “CBC” RC3 estimation algorithm. Additionally, the formulation of a diagnostic CBC and serum chemistry “CBC-SCHEM” RC3 algorithm expanded upon the CBC algorithm model with the addition of hematocrit and the serum enzyme levels of aspartate aminotransferase, creatine kinase, and lactate dehydrogenase. Both algorithms estimated RC3 with over 90% predictive power. Only the CBC-SCHEM RC3 algorithm, however, met the critical three assumptions of linear least squares demonstrating slightly greater precision for radiation injury estimation, but with significantly decreased prediction error indicating increased statistical robustness. PMID:25165485

  10. Applications of radiation measurements in arms control and nonproliferation

    NASA Astrophysics Data System (ADS)

    Leich, D.; Reinitz, K.; Barnette, S.; O'Connell, M.; Sheely, K.

    1994-12-01

    Radiation measurements play a vital role in the development and implementation of U.S. arms control and nonproliferation policy. The President's Nonproliferation and Export Control Policy reflects the changing realities of a post-Cold-War world and makes nonproliferation one of our nation's highest priorities. Key elements of the Policy concern international controls on plutonium and highly-enriched uranium. Current DOE work contributing to arms control and nonproliferation policy implementation is described with an emphasis on the role of radiation measurements.

  11. "Investigation of Trends in Aerosol Direct Radiative Effects over North America Using a Coupled Meteorology-Chemistry Model"

    EPA Science Inventory

    While aerosol radiative effects have been recognized as some of the largest sources of uncertainty among the forcers of climate change, there has been little effort devoted to verification of the spatial and temporal variability of the magnitude and directionality of aerosol radi...

  12. Impact of resolution on aerosol radiative feedbacks with in online-coupled chemistry/climate simulations (WRF-Chem) for EURO-CORDEX compliant domains

    NASA Astrophysics Data System (ADS)

    López-Romero, Jose Maria; Baró, Rocío; Palacios-Peña, Laura; Jerez, Sonia; Jiménez-Guerrero, Pedro; Montávez, Juan Pedro

    2016-04-01

    Several studies have shown that a high spatial resolution in atmospheric model runs improves the simulation of some meteorological variables, such as precipitation, particularly extreme events and in regions with complex orography [1]. However, increasing model spatial resolution makes the computational time rise exponentially. Hence, very high resolution experiments on large domains can hamper the execution of climatic runs. This problem shoots up when using online-coupled chemistry climate models, making a careful evaluation of improvements versus costs mandatory. Under this umbrella, the objective of this work is to investigate the sensitivity of aerosol radiative feedbacks from online-coupled chemistry regional model simulations to the spatial resolution. For that, the WRF-Chem [2] model is used for a case study to simulate the episode occurring between July 25th and August 15th of 2010. It is characterized by a high loading of atmospheric aerosol particles coming mainly from wildfires over large European regions (Russia, Iberian Peninsula). Three spatial resolutions are used defined for Euro-Cordex compliant domains [3]: 0.44°, 0.22° and 0.11°. Anthropogenic emissions come from TNO databases [4]. The analysis focuses on air quality variables (mainly PM10, PM2.5), meteorological variables (temperature, radiation) and other aerosol optical properties (aerosol optical depth). The CPU time ratio for the different domains is 1 (0.44°), 4(0.22°) and 28(0.11°) (normalized times). Comparison among simulations and observations are analyzed. Preliminary results show the difficulty to justify the much larger computational cost of high-resolution experiments when comparing with observations from a meteorological point of view, despite the finer spatio-temporal detail of the obtained pollutant fields. [1] Prein, A. F. (2014, December). Precipitation in the EURO-CORDEX 0.11° and 0.44° simulations: high resolution, high benefits?. In AGU Fall Meeting Abstracts (Vol

  13. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Inter-comparison Project (ACCMIP)

    NASA Astrophysics Data System (ADS)

    Stevenson, D. S.; Young, P. J.; Naik, V.; Lamarque, J.-F.; Shindell, D. T.; Voulgarakis, A.; Skeie, R. B.; Dalsoren, S. B.; Myhre, G.; Berntsen, T. K.; Folberth, G. A.; Rumbold, S. T.; Collins, W. J.; MacKenzie, I. A.; Doherty, R. M.; Zeng, G.; van Noije, T. P. C.; Strunk, A.; Bergmann, D.; Cameron-Smith, P.; Plummer, D. A.; Strode, S. A.; Horowitz, L.; Lee, Y. H.; Szopa, S.; Sudo, K.; Nagashima, T.; Josse, B.; Cionni, I.; Righi, M.; Eyring, V.; Conley, A.; Bowman, K. W.; Wild, O.

    2012-10-01

    Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). We calculate a~value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 0.40 W m-2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (47%), nitrogen oxides (29%), carbon monoxide (15%) and non-methane volatile organic compounds (9%); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 0.042 W m-2 DU-1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (W m-2; relative to 1850 - add 0.04 W m-2 to make relative to 1750) for the Representative Concentration Pathways in 2030 (2100) of: RCP2.6: 0.31 (0.16); RCP4.5: 0.38 (0.26); RCP6.0: 0.33 (0.24); and RCP8.5: 0.42 (0.56). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport.

  14. A new application of click chemistry in situ: development of fluorescent probe for specific G-quadruplex topology.

    PubMed

    Hu, Ming-Hao; Chen, Xiao; Chen, Shuo-Bin; Ou, Tian-Miao; Yao, Meicun; Gu, Lian-Quan; Huang, Zhi-Shu; Tan, Jia-Heng

    2015-11-25

    Target-guided synthesis is an approach to drug discovery that allows the target to self-assemble its own binding agents. So far, target-guided synthesis and especially in situ click chemistry have attracted extensive attention and have led to the identification of highly potent inhibitors for proteins. In this study, we expand the application of in situ click chemistry and present a procedure using this approach to identify selective fluorescent probes for a specific topology of G-quadruplex nucleic acids, the parallel G-quadruplexes. On this basis, compound 15 assembled by triarylimidazole scaffold and carboxyl side chain was a positive hit, demonstrating highly potential in the sensitive and selective detection of parallel G-quadruplexes. Such selective fluorescence response can be rationalized in terms of different binding affinities between 15 and G-quadruplexes. Our work accordingly represents a new development towards the application of in situ click chemistry to develop selective fluorescent probes and may also shed light on the search for probes for a specific G-quadruplex topology.

  15. Novel detection schemes of nuclear magnetic resonance and magnetic resonance imaging: applications from analytical chemistry to molecular sensors.

    PubMed

    Harel, Elad; Schröder, Leif; Xu, Shoujun

    2008-01-01

    Nuclear magnetic resonance (NMR) is a well-established analytical technique in chemistry. The ability to precisely control the nuclear spin interactions that give rise to the NMR phenomenon has led to revolutionary advances in fields as diverse as protein structure determination and medical diagnosis. Here, we discuss methods for increasing the sensitivity of magnetic resonance experiments, moving away from the paradigm of traditional NMR by separating the encoding and detection steps of the experiment. This added flexibility allows for diverse applications ranging from lab-on-a-chip flow imaging and biological sensors to optical detection of magnetic resonance imaging at low magnetic fields. We aim to compare and discuss various approaches for a host of problems in material science, biology, and physics that differ from the high-field methods routinely used in analytical chemistry and medical imaging.

  16. Refinement, Application, and Evaluation of Cognitive and Affective Chemistry Measures for College Students

    NASA Astrophysics Data System (ADS)

    Heredia, Keily

    This work describes three case studies conducted to address two major problems in the area of chemistry education research, the lack of reported psychometrics regarding instrument scores, and the need for well-characterized assessments to evaluate college chemistry curricula. The first case study describes a psychometric evaluation of the Colorado Learning Attitudes about Science Survey (CLASS), an instrument designed to assess student beliefs about the learning of chemistry. Results from this work suggest that the CLASS instrument provides fertile ground for short instruments with reasonable psychometric properties. Responses to a single scale instrument, created from CLASS, showed that students in an introductory general chemistry course tend to be slightly more expert-like than novice-like in their beliefs about chemistry towards the end of the semester. The second case study discusses the use of a two-tier diagnostic instrument in assessing student understanding of the particulate nature of matter and chemical bonding. In addition to examining psychometric properties of the instrument's scores, this study uses student responses to think about the role of a preparatory chemistry course in promoting understanding of the measured concepts. Results of this study showed that the performance of students with the preparatory chemistry course was slightly better than those without it. The third case study focuses on the development of the Targeted Misconception Inventory (TMI), a two-tier instrument designed to measure student understanding of Bond Energy, Ionic, Bonding, and Phase Changes. The TMI was used to create an instructional intervention. Results from the intervention suggested a learning gain for Bond Energy concept. The three instruments discussed above were multiple-choice given as paper and pencil tests in an introductory chemistry course. The work described in this dissertation showcase a method for examining psychometric evidence. The three case studies

  17. Application of validated radiation model in flame spread rate over solid fuels

    NASA Astrophysics Data System (ADS)

    Ivisic, Ivan

    In this thesis the radiative effects of opposed flow flames spreading over solid fuels are discussed as well as the coupling of a radiation and CFD program. The coupled programs are used to show the radiative heat transfer mechanisms and how they affect the flame globally. A radiation program is used to calculate radiation properties of the flame such as the heat flux distribution, net heat flow, and mean Plank absorptivity constant for a particular flame. The radiation program imports the temperature fields from a CFD program. Trends in the mean Plank absorptivity constant with varying ambient conditions are analyzed and an application of the radiation program to simulate a physical radiometer is demonstrated for a test case. The CFD program can import radiation results to help improve the accuracy of the simulation. A script was written to automate the update process to produce more accurate results for flame simulations. Flux distributions, stability and relative error are analyzed to show the coupled programs are producing results within an acceptable error. Trends in error and stability are discussed and stable regions with low enough error are determined. The coupled programs are used to gather data on flame spread rate and find differences in flame structure and properties of neglecting certain radiation mechanisms. No radiation included produced the hottest fastest moving flame, while no gas to surface radiation produced the coolest flame. Including the gas to surface radiation produced a slightly hotter faster moving flame. This trend was studied across different opposed flow velocities and sample widths. The radiative heat fluxes are analyzed for the cases as well. All the flame simulations in this thesis were run for a microgravity, 21% oxygen, and PMMA fuel.

  18. Effect of long-term application of biosolids for land reclamation on surface water chemistry.

    PubMed

    Tian, G; Granato, T C; Pietz, R I; Carlson, C R; Abedin, Z

    2006-01-01

    Biosolids are known to have a potential to restore degraded land, but the long-term impacts of this practice on the environment, including water quality, still need to be evaluated. The surface water chemistry (NO3-, NH4+, and total P, Cd, Cu, and Hg) was monitored for 31 yr from 1972 to 2002 in a 6000-ha watershed at Fulton County, Illinois, where the Metropolitan Water Reclamation District of Greater Chicago was restoring the productivity of strip-mined land using biosolids. The mean cumulative loading rates during the past 31 yr were 875 dry Mg ha(-1) for 1120-ha fields in the biosolids-amended watershed and 4.3 dry Mg ha(-1) for the 670-ha fields in the control watershed. Biosolids were injected into mine spoil fields as liquid fertilizer from 1972 to 1985, and incorporated as dewatered cake from 1980 to 1996 and air-dried solids from 1987 to 2002. The mean annual loadings of nutrients and trace elements from biosolids in 1 ha were 735 kg N, 530 kg P, 4.5 kg Cd, 30.7 kg Cu, and 0.11 kg Hg in the fields of the biosolids-amended watershed, and negligible in the fields of the control watershed. Sampling of surface water was conducted monthly in the 1970s, and three times per year in the 1980s and 1990s. The water samples were collected from 12 reservoirs and 2 creeks receiving drainage from the fields in the control watershed, and 8 reservoirs and 4 creeks associated with the fields in the biosolids-amended watershed for the analysis of NO3- -N (including NO2- N), NH4+-N, and total P, Cd, Cu, and Hg. Compared to the control (0.18 mg L(-1)), surface water NO3- -N in the biosolids-amended watershed (2.23 mg L(-1)) was consistently higher; however, it was still below the Illinois limit of 10 mg L(-1) for public and food-processing water supplies. Biosolids applications had a significant effect on mean concentrations of ammonium N (0.11 mg L(-1) for control and 0.24 mg L(-1) for biosolids) and total P (0.10 mg L(-1) for control and 0.16 mg L(-1) for biosolids) in

  19. The application of two-dimensional centrifugation to clinical chemistry testing.

    PubMed

    Holen, J T; Schultz, S G; Wong, S T

    1986-01-01

    We have developed a new clinical chemistry analyzer, the VISION System, which uses centrifugal force to separate whole blood, measure reagent and plasma volumes, and complete all steps required for a spectrophotometric analysis. The system is based on a multichambered test pack containing liquid reagents, which can be centrifuged in two planes oriented at right angles to each other. The analyzer regulates the temperature, timing and optical measurements for up to 10 different test packs in the same run. We have demonstrated good precision and accuracy on 6 clinical chemistry analytes, 2 enzymes, potassium and theophylline using this system.

  20. Oxygen chemistry in biology: Vibrational spectroscopy, stable isotopes, and future applications

    SciTech Connect

    Babcock, G.T.

    1994-12-01

    Dioxygen is an ideally suited substrate for enzymatic manipulation in oxidation-reduction chemistry and in substrate transformation. It is a powerful oxidant with a midpoint potential of 0.815 at neutral pH; at the same time, however, it exists in a triplet state in its most stable electronic configuration. This latter property confers kinetic inertness as a result of spin-conservation restrictions on reaction chemistry. If these restrictions can be overcome and controlled, dioxygen`s high redox potential can be used to maximize efficiency in free-energy conversion processes and to effect activation of relatively inert substrates.

  1. Application of nonlinear Krylov acceleration to radiative transfer problems

    SciTech Connect

    Till, A. T.; Adams, M. L.; Morel, J. E.

    2013-07-01

    The iterative solution technique used for radiative transfer is normally nested, with outer thermal iterations and inner transport iterations. We implement a nonlinear Krylov acceleration (NKA) method in the PDT code for radiative transfer problems that breaks nesting, resulting in more thermal iterations but significantly fewer total inner transport iterations. Using the metric of total inner transport iterations, we investigate a crooked-pipe-like problem and a pseudo-shock-tube problem. Using only sweep preconditioning, we compare NKA against a typical inner / outer method employing GMRES / Newton and find NKA to be comparable or superior. Finally, we demonstrate the efficacy of applying diffusion-based preconditioning to grey problems in conjunction with NKA. (authors)

  2. General Relativistic Radiative Transfer: Applications to Black-Hole Systems

    NASA Technical Reports Server (NTRS)

    Wu, Kinwah; Fuerst, Steven V.; Mizuno, Yosuke; Nishikawa, Ken-Ichi; Branduardi-Raymont, Graziella; Lee, Khee-Gan

    2007-01-01

    We present general relativistic radiation transfer formulations which include opacity effects due to absorption, emission and scattering explicitly. We consider a moment expansions for the transfer in the presence of scattering. The formulation is applied to calculation emissions from accretion and outflows in black-hole systems. Cases with thin accretion disks and accretion tori are considered. Effects, such as emission anisotropy, non-stationary flows and geometrical self-occultation are investigated. Polarisation transfer in curved space-time is discussed qualitatively.

  3. Novel Human Radiation Exposure Biomarker Panel Applicable for Population Triage

    SciTech Connect

    Bazan, Jose G.; Chang, Polly; Balog, Robert; D'Andrea, Annalisa; Shaler, Thomas; Lin, Hua; Lee, Shirley; Harrison, Travis; Shura, Lei; Schoen, Lucy; Knox, Susan J.; Cooper, David E.

    2014-11-01

    Purpose: To identify a panel of radiation-responsive plasma proteins that could be used in a point-of-care biologic dosimeter to detect clinically significant levels of ionizing radiation exposure. Methods and Materials: Patients undergoing preparation for hematopoietic cell transplantation using radiation therapy (RT) with either total lymphoid irradiation or fractionated total body irradiation were eligible. Plasma was examined from patients with potentially confounding conditions and from normal individuals. Each plasma sample was analyzed for a panel of 17 proteins before RT was begun and at several time points after RT exposure. Paired and unpaired t tests between the dose and control groups were performed. Conditional inference trees were constructed based on panels of proteins to compare the non-RT group with the RT group. Results: A total of 151 patients (62 RT, 41 infection, 48 trauma) were enrolled on the study, and the plasma from an additional 24 healthy control individuals was analyzed. In comparison with to control individuals, tenascin-C was upregulated and clusterin was downregulated in patients receiving RT. Salivary amylase was strongly radiation responsive, with upregulation in total body irradiation patients and slight downregulation in total lymphoid irradiation patients compared with control individuals. A panel consisting of these 3 proteins accurately distinguished between irradiated patients and healthy control individuals within 3 days after exposure: 97% accuracy, 0.5% false negative rate, 2% false positive rate. The accuracy was diminished when patients with trauma, infection, or both were included (accuracy, 74%-84%; false positive rate, 14%-33%, false negative rate: 8%-40%). Conclusions: A panel of 3 proteins accurately distinguishes unirradiated healthy donors from those exposed to RT (0.8-9.6 Gy) within 3 days of exposure. These findings have significant implications in terms of triaging individuals in the case of nuclear or other

  4. Radiation Thermodynamics with Applications to Lasing and Fluorescent Cooling

    DTIC Science & Technology

    2005-04-01

    the flux temperatures of the fluorescence and pump radiation, respectively. The reversible Carnot limit is obtained by choosing the equality sign in...into light and can be interpreted as an optically pumped laser running in reverse . Optical pumping in such devices drives the level populations out of...relaxation cycle . The simplest possible level scheme of such an absorber is depicted in Fig. 2. The material has only three energy levels, where level 1

  5. Radiation pressure confinement - IV. Application to broad absorption line outflows

    NASA Astrophysics Data System (ADS)

    Baskin, Alexei; Laor, Ari; Stern, Jonathan

    2014-12-01

    A fraction of quasars present broad absorption lines, produced by outflowing gas with typical velocities of 3000-10 000 km s-1. If the outflowing gas fills a significant fraction of the volume where it resides, then it will be highly ionized by the quasar due to its low density, and will not produce the observed UV absorption. The suggestion that the outflow is shielded from the ionizing radiation was excluded by recent observations. The remaining solution is a dense outflow with a filling factor f < 10-3. What produces such a small f? Here, we point out that radiation pressure confinement (RPC) inevitably leads to gas compression and the formation of dense thin gas sheets/filaments, with a large gradient in density and ionization along the line of sight. The total column of ionized dustless gas is a few times 1022 cm-2, consistent with the observed X-ray absorption and detectable P V absorption. The predicted maximal columns of various ions show a small dependence on the system parameters, and can be used to test the validity of RPC as a solution for the overionization problem. The ionization structure of the outflow implies that if the outflow is radiatively driven, then broad absorption line quasars should have L/L_Eddgtrsim 0.1.

  6. Optimization of a radiative membrane for gas sensing applications

    NASA Astrophysics Data System (ADS)

    Lefebvre, Anthony; Boutami, Salim; Greffet, Jean-Jacques; Benisty, Henri

    2014-05-01

    To engineer a cheap, portable and low-power optical gas sensor, incandescent sources are more suitable than expensive quantum cascade lasers and low-efficiency light-emitting diodes. Such sources of radiation have already been realized, using standard MEMS technology, consisting in free standing circular micro-hotplates. This paper deals with the design of such membranes in order to maximize their wall-plug efficiency. Specification constraints are taken into account, including available energy per measurement and maximum power delivered by the electrical supply source. The main drawback of these membranes is known to be the power lost through conduction to the substrate, thus not converted in (useful) radiated power. If the membrane temperature is capped by technological requirements, radiative flux can be favored by increasing the membrane radius. However, given a finite amount of energy, the larger the membrane and its heat capacity, the shorter the time it can be turned on. This clearly suggests that an efficiency optimum has to be found. Using simulations based on a spatio-temporal radial profile, we demonstrate how to optimally design such membrane systems, and provide an insight into the thermo-optical mechanisms governing this kind of devices, resulting in a nontrivial design with a substantial benefit over existing systems. To further improve the source, we also consider tailoring the membrane stack spectral emissivity to promote the infrared signal to be sensed as well as to maximize energy efficiency.

  7. Preliminary evaluation of a liquid belt radiator for space applications

    NASA Technical Reports Server (NTRS)

    Teagan, W. P.; Fitzgerald, K.

    1984-01-01

    The liquid belt radiator (LBR) is discussed. The LBR system operates either in the sensible heat mode or in the latent heat mode. Parametric analysis shows that the LBR may reduce the mass of heat pipe radiators by 70 to 90% when the LBR surface has a total emissivity in excess of 0.3. It is indicated that the diffusion pump oils easily meet this criteria with emissivities greater than 0.8. Measurements on gallium indicate that its emissivity is probably in excess of 0.3 in the solid state when small amounts of impurities are on the surface. The point design exhibits a characteristic mass of 3.1 kg/kW of power dissipation, a mass per unit prime radiating area of approximately 0.9 kg/sq ms and a total package volume of approximately 2.50 cubic m. This compares favorably with conventional technologies which have weights on the order of 4 kg/sq m.

  8. Application of Multivariate Modeling for Radiation Injury Assessment: A Proof of Concept (Radiation Injury Algorithms)

    DTIC Science & Technology

    2014-01-01

    amylase , C - reactive protein (CRP), and hematological blood-cell counts measured at 1 - 4 d post-radiation exposure. A recent study by Moroni [19...known to manifest in the prodromal and/or late ARS phases (Flt3 ligand, Citrulline, C-reactive protein, serum amylase IL-6) may contribute to our...Salter, I. H. Levine, W. E. Jackson, M. B. Grace, P. G. S. Prasanna, D. J. Sandgren, and G .D. Ledney, ― Amylase and blood cell-count hematological

  9. TOMS as a monitor of the ultraviolet radiation environment: Applications to photobiology

    NASA Technical Reports Server (NTRS)

    Frederick, John E.

    1987-01-01

    The flux of biologically relevant ultraviolet radiation that reaches the surface of the Earth varies with the ozone amount, surface reflectivity, and cloudcover. The Total Ozone Mapping Spectrometer (TOMS) provides information relevant to all three items. A recent application of satellite-based ozone measurements has been to develop climatologies of the biologically significant UV-B radiation reaching the Earth's surface. A growing body of research suggests that UV-B radiation tends to suppress the immune system of laboratory mice. At tropical latitudes, it is likely that parasitical diseases develop most readily in people who have experienced immune system suppression from UV-B exposure. The computed distribution of surface radiation combined with information on disease incidence may clarify the role of UV-B as a suppressor of the human immune system. TOMS used in conjunction with radiative transfer calculations can provide information of relevance in photobiology.

  10. Radiative Transfer in Earth Re-entry: Application to the Project Fire II Experiments

    NASA Astrophysics Data System (ADS)

    Lamet, J.-M.; Babou, Y.; Riviere, Ph.; Soufiani, A.; Perrin, M.-Y.

    2006-11-01

    The aim of this paper is to contribute to the test case 6 by computing the radiative heat intensities at the stagnation point for four points of Fire II re-entry trajectory. The prescribed flow-fields provided in the test case booklet are used. The radiative heat flux computations are based on a line by line approach combined with the exhaustive database which has been developed previously [1, 2]. The previous benchmarking of air radiative properties on a LTE air plasma have shown the quality of this database [3]. Since then, the use of this database has been extended to non LTE applications. In addition to the radiation computations defined in test case 6, the spectral distribution of the different intensities is predicted on a wide spectral range from far UV to IR. This will be important for further flow/radiation coupling studies. Different modelling levels are tested: pure emission, absorption effects, and chemical nonequilibrium effects.

  11. Radiation-hardened CMOS integrated circuit development for space nuclear power applications

    NASA Astrophysics Data System (ADS)

    Gover, J. E.; Gregory, B. L.

    Examination of the types of systems required for space nuclear power applications suggests a need for microelectronics technology that can function during and after exposure to radiation levels exceeding 1 x 10 to the 16th neutrons/sq cm and gamma ray doses in excess of 1 x 10 to the 7th rad(Si). Radiation-hardened Complimentary Metal Oxide Silicon and Silicon Nitride Oxide Silicon (SNOS) ICs presently in development at Sandia National Laboratories' Center for Radiation-Hardened Microelectronics satisfy these radiation requirements. Future integrated circuit development will further advance the radiation hardness capabilities while extending the IC technology to 32-bit enhanced microprocessors and 1-Mbyte SNOS EEPROM memories.

  12. Application of Calibrated Peer Review (CPR) Writing Assignments to Enhance Experiments with an Environmental Chemistry Focus

    ERIC Educational Resources Information Center

    Margerum, Lawrence D.; Gulsrud, Maren; Manlapez, Ronald; Rebong, Rachelle; Love, Austin

    2007-01-01

    The browser-based software program, Calibrated Peer Review (CPR) developed by the Molecular Science Project enables instructors to create structured writing assignments in which students learn by writing and reading for content. Though the CPR project covers only one experiment in general chemistry, it might provide lab instructors with a method…

  13. A Review of Literature Reports of Clickers Applicable to College Chemistry Classrooms

    ERIC Educational Resources Information Center

    MacArthur, James R.; Jones, Loretta L.

    2008-01-01

    The use of clickers (also referred to as Audience Paced Feedback, Classroom Communication Systems, Personal Response Systems, Electronic Voting Systems, Student Response Systems, Audience Response Systems, voting-machines, and zappers) has grown in college chemistry classrooms within the last decade. This review summarizes the pedagogic…

  14. STRATEGIES FOR GREEN REACTION CHEMISTRIES: APPLICATION OF GREEN CATALYSIS AND PROCESS INTENSIFICATION

    EPA Science Inventory

    An intramural research effort within the Sustainable Technology Division (STD) is focused on the development of novel technologies for the synthesis of chemicals in a green and sustainable manner. To extend on the scope of green chemistry, this research also incorporates enginee...

  15. Microwave-Assisted Chemistry: Synthetic Applications for Rapid Assembly of Nanomaterials and Organics

    EPA Science Inventory

    The magic of microwave (MW) heating technique, termed as the Bunsen burner of the 21th Century, has emerged as valuable alternative in synthesis of organics, polymers, inorganics, and nanomaterials. Important innovations in MW-assisted chemistry now enable chemists to prepare cat...

  16. Applications of dynamic nuclear polarization to the study of reactions and reagents in organic and biomolecular chemistry.

    PubMed

    Hilty, Christian; Bowen, Sean

    2010-08-07

    Nuclear Magnetic Resonance (NMR) is an important spectroscopic tool for the identification and structural characterization of molecules in chemistry and biochemistry. The most significant limitation of NMR compared to other spectroscopies is its relatively low sensitivity, which thus often requires long measurement times or large amounts of sample. A way of increasing sensitivity of single scan NMR spectra by several orders of magnitude is through hyperpolarization of nuclear spins. Dynamic nuclear polarization allows hyperpolarization of most spins in small molecules encountered in chemistry and biochemistry. NMR spectra of small amounts of samples from natural source, or from chemical synthesis can readily be acquired. Perhaps more interestingly, the availability of the entire hyperpolarized NMR signal in one single scan allows the measurement of transient processes in real time, if applied together with a stopped-flow technique. Through observation of chemical shift, different reactant and product species can be distinguished, and kinetics and mechanisms, for example in enzyme catalyzed reactions, can be elucidated. Real-time hyperpolarization-enhanced NMR is uniquely amenable to correlating atomic positions not only through space, but also over time between reactant and product species. Such correlations carry mechanistic information about a reaction, and can prove reaction pathways. Applications of this technique are emerging in different areas of chemistry concerned with rapid reactions, including not only enzymatic processes, but also chemical catalysis and protein folding.

  17. Dynamic Electrothermal Model of a Sputtered Thermopile Thermal Radiation Detector for Earth Radiation Budget Applications

    NASA Technical Reports Server (NTRS)

    Weckmann, Stephanie

    1997-01-01

    The Clouds and the Earth's Radiant Energy System (CERES) is a program sponsored by the National Aeronautics and Space Administration (NASA) aimed at evaluating the global energy balance. Current scanning radiometers used for CERES consist of thin-film thermistor bolometers viewing the Earth through a Cassegrain telescope. The Thermal Radiation Group, a laboratory in the Department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently studying a new sensor concept to replace the current bolometer: a thermopile thermal radiation detector. This next-generation detector would consist of a thermal sensor array made of thermocouple junction pairs, or thermopiles. The objective of the current research is to perform a thermal analysis of the thermopile. Numerical thermal models are particularly suited to solve problems for which temperature is the dominant mechanism of the operation of the device (through the thermoelectric effect), as well as for complex geometries composed of numerous different materials. Feasibility and design specifications are studied by developing a dynamic electrothermal model of the thermopile using the finite element method. A commercial finite element-modeling package, ALGOR, is used.

  18. Application of Histogram Analysis in Radiation Therapy (HART) in Intensity Modulation Radiation Therapy (IMRT) Treatments

    NASA Astrophysics Data System (ADS)

    Pyakuryal, Anil

    2009-03-01

    A carcinoma is a malignant cancer that emerges from epithelial cells in structures through out the body.It invades the critical organs, could metastasize or spread to lymph nodes.IMRT is an advanced mode of radiation therapy treatment for cancer. It delivers more conformal doses to malignant tumors sparing the critical organs by modulating the intensity of radiation beam.An automated software, HART (S. Jang et al.,2008,Med Phys 35,p.2812) was used for efficient analysis of dose volume histograms (DVH) for multiple targets and critical organs in four IMRT treatment plans for each patient. IMRT data for ten head and neck cancer patients were exported as AAPM/RTOG format files from a commercial treatment planning system at Northwestern Memorial Hospital (NMH).HART extracted DVH statistics were used to evaluate plan indices and to analyze dose tolerance of critical structures at prescription dose (PD) for each patient. Mean plan indices (n=10) were found to be in good agreement with published results for Linac based plans. The least irradiated volume at tolerance dose (TD50) was observed for brainstem and the highest volume for larynx in SIB treatment techniques. Thus HART, an open source platform, has extensive clinical implications in IMRT treatments.

  19. Growth and applicability of radiation-responsive silica nanowires

    NASA Astrophysics Data System (ADS)

    Bettge, Martin

    -phase line with 670-850 mJ-m-2. Our analysis further reveals the existence of an additional force at this line that behaves as a negative line tension (or line energy). Its contribution is relatively small, but important for stable and small nanowire growth. The value of the line tension lies in the range of -0.1 to -1.0 nJ-m-1. Spontaneous alignment of these stranded, free-standing wires toward a source of directional ion irradiation is proposed to be driven by local surface area minimization. An intuitive model for this is provided and experimentally verified through post-growth reorientation of nanowire patterns over a wide range of angles with standard focused ion beam instrumentation. Ion-induced orientation control and modification of nanowire arrays might prove to be a powerful method for nanoscale surface engineering, potentially leading to surfaces with well-organized anisotropic topographies. Another potential application of aligned silica nanowires as templates for highly textured electrodes in lithium-ion batteries is also discussed. As textured thin films are expected to provide better cycle life and enhanced charge transport, their electrochemical performance is compared to planar thin films of equal mass using two secondary materials (amorphous silicon and lithium manganese oxide). Both materials are applied directly onto the wire arrays by conventional deposition tools and galvanostatically cycled against metallic lithium. Textured silicon films, for use as negative materials, show improved capacity retention compared to planar thin films. Capacity fade is found to be relatively constant at about 0.8% per cycle over 30 cycles. Significant charge trapping occurred due to massive formation of a solid-electrolyteinterface. Electrochemical cycling and impedance spectroscopy further demonstrate that kinetic and electrochemical behavior of the electrode is qualitatively similar for planar and for highly textured silicon thin films. Textured films of lithium

  20. Applications of synchrotron radiation to materials science: Diffraction imaging (topography) and microradiography

    NASA Technical Reports Server (NTRS)

    Kuriyama, Masao

    1988-01-01

    Synchrotron radiation sources are now available throughout the world. The use of hard X-ray radiation from these sources for materials science is described with emphasis on diffraction imaging for material characterization. With the availability of synchrotron radiation, real-time in situ measurements of dynamic microstructural phenomena have been started. This is a new area where traditional application of X-rays has been superseded. Examples are chosen from limited areas and are by no means exhaustive. The new emerging information will, no doubt, have great impact on materials science and engineering.

  1. Microwave-assisted chemistry: synthetic applications for rapid assembly of nanomaterials and organics.

    PubMed

    Gawande, Manoj B; Shelke, Sharad N; Zboril, Radek; Varma, Rajender S

    2014-04-15

    The magic of microwave (MW) heating technique, termed the Bunsen burner of the 21st century, has emerged as a valuable alternative in the synthesis of organic compounds, polymers, inorganic materials, and nanomaterials. Important innovations in MW-assisted chemistry now enable chemists to prepare catalytic materials or nanomaterials and desired organic molecules, selectively, in almost quantitative yields and with greater precision than using conventional heating. By controlling the specific MW parameters (temperature, pressure, and ramping of temperature) and choice of solvents, researchers can now move into the next generation of advanced nanomaterial design and development. Microwave-assisted chemical reactions are now well-established practices in the laboratory setting although some controversy lingers as to how MW irradiation is able to enhance or influence the outcome of chemical reactions. Much of the discussion has focused on whether the observed effects can, in all instances, be rationalized by purely thermal Arrhenius-based phenomena (thermal microwave effects), that is, the importance of the rapid heating and high bulk reaction temperatures that are achievable using MW dielectric heating in sealed reaction vessels, or whether these observations can be explained by so-called "nonthermal" or "specific microwave" effects. In recent years, innovative and significant advances have occurred in MW hardware development to help delineate MW effects, especially the use of silicon carbide (SiC) reaction vessels and the accurate measurement of temperature using fiber optic (FO) temperature probes. SiC reactors appear to be good alternatives to MW transparent borosilicate glass, because of their high microwave absorptivity, and as such they serve as valuable tools to demystify the claimed magical MW effects. This enables one to evaluate the influence of the electromagnetic field on the specific chemical reactions, under truly identical conventional heating

  2. Synchrotron radiation applications in medical research at Brookhaven National Laboratory

    SciTech Connect

    Thomlinson, W.

    1997-08-01

    In the relatively short time that synchrotrons have been available to the scientific community, their characteristic beams of UV and X-ray radiation have been applied to virtually all areas of medical science which use ionizing radiation. The ability to tune intense monochromatic beams over wide energy ranges clearly differentiates these sources from standard clinical and research tools. The tunable spectrum, high intrinsic collimation of the beams, polarization and intensity of the beams make possible in-vitro and in-vivo research and therapeutic programs not otherwise possible. From the beginning of research operation at the National Synchrotron Light Source (NSLS), many programs have been carrying out basic biomedical research. At first, the research was limited to in-vitro programs such as the x-ray microscope, circular dichroism, XAFS, protein crystallography, micro-tomography and fluorescence analysis. Later, as the coronary angiography program made plans to move its experimental phase from SSRL to the NSLS, it became clear that other in-vivo projects could also be carried out at the synchrotron. The development of SMERF (Synchrotron Medical Research Facility) on beamline X17 became the home not only for angiography but also for the MECT (Multiple Energy Computed Tomography) project for cerebral and vascular imaging. The high energy spectrum on X17 is necessary for the MRT (Microplanar Radiation Therapy) experiments. Experience with these programs and the existence of the Medical Programs Group at the NSLS led to the development of a program in synchrotron based mammography. A recent adaptation of the angiography hardware has made it possible to image human lungs (bronchography). Fig. 1 schematically depicts the broad range of active programs at the NSLS.

  3. Solar Cycle Variation and Application to the Space Radiation Environment

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Kim, Myung-Hee Y.; Shinn, Judy L.; Tai, Hsiang; Cucinotta, Francis A.; Badhwar, Gautam D.; Badavi, Francis F.; Atwell, William

    1999-01-01

    The interplanetary plasma and fields are affected by the degree of disturbance that is related to the number and types of sunspots in the solar surface. Sunspot observations were improved with the introduction of the telescope in the seventeenth century, allowing observations which cover many centuries. A single quantity (sunspot number) was defined by Wolf in 1848 that is now known to be well correlated with many space observable quantities and is used herein to represent variations caused in the space radiation environment. The resultant environmental models are intended for future aircraft and space-travel-related exposure estimates.

  4. The diffusion approximation. An application to radiative transfer in clouds

    NASA Technical Reports Server (NTRS)

    Arduini, R. F.; Barkstrom, B. R.

    1976-01-01

    It is shown how the radiative transfer equation reduces to the diffusion equation. To keep the mathematics as simple as possible, the approximation is applied to a cylindrical cloud of radius R and height h. The diffusion equation separates in cylindrical coordinates and, in a sample calculation, the solution is evaluated for a range of cloud radii with cloud heights of 0.5 km and 1.0 km. The simplicity of the method and the speed with which solutions are obtained give it potential as a tool with which to study the effects of finite-sized clouds on the albedo of the earth-atmosphere system.

  5. The Use of Synchrotron Radiation of Electron Circles in Applications

    NASA Astrophysics Data System (ADS)

    Anevsky, S. I.; Vernyi, A. Ye; Panasyuk, V. S.; Sapritsky, V. I.

    1987-05-01

    The use of the synchrotron radiation (SR) in the vacuum ultraviolet (VUV) spectroscopy and radiometry opens new doors for a researcher. In this connection a consideration of SR characteristics of small size specialized SR sources, which can be available even in single laboratories, is given below. "TROLL" is an electron synchrotron with a cyclotron preacceleration. It has been developed as a specialized SR source for the calibration of VUV sources as secondary standards in the spectral range of 40-250 nm in the units of spectral radiance. In conclusion there is summary of advantages of small size accelerators.

  6. Electromagnetic radiation screening of semiconductor devices for long life applications

    NASA Technical Reports Server (NTRS)

    Hall, T. C.; Brammer, W. G.

    1972-01-01

    A review is presented of the mechanism of interaction of electromagnetic radiation in various spectral ranges, with various semiconductor device defects. Previous work conducted in this area was analyzed as to its pertinence to the current problem. The task was studied of implementing electromagnetic screening methods in the wavelength region determined to be most effective. Both scanning and flooding type stimulation techniques are discussed. While the scanning technique offers a considerably higher yield of useful information, a preliminary investigation utilizing the flooding approach is first recommended because of the ease of implementation, lower cost and ability to provide go-no-go information in semiconductor screening.

  7. Radiation passport: an iPhone and iPod touch application to track radiation dose and estimate associated cancer risks.

    PubMed

    Baerlocher, Mark Otto; Talanow, Roland; Baerlocher, Adrian F

    2010-04-01

    The rapid increase in the use of radiology and related exams and procedures has led to a concomitant increase in associated radiation risk. An application for the iPhone and iPod Touch called 'Radiation Passport' is described, which provides radiation dose estimates and associated cancer risks (non fatal and fatal) and serves as a method by which to track an individual's cumulative exposure.

  8. Application of new technologies to radiation biodosimetry in mammalian systems

    NASA Astrophysics Data System (ADS)

    Sutherland, R. M.; Lord, E. M.; Keng, P. C.

    1986-02-01

    Mononuclear cells from peripheral blood are presently the best candidates for a space radiation biodosimeter for man because they are easily obtained, and are among the most radiosensitive cells in the body. They are, however, members of a highly heterogeneous population of cell subtypes potentially differing in radiosensitivities. To study the cell subpopulation holding the greatest potential for use as a biodosimeter, the cell types must be uniquely identified, and/or separated so that subtle effects on radiosensitive cells are not masked by non-effects on relatively radioresistant cells present in a mixed population. Flow cytometry and centrifugal elutriation are proving to be useful for identifying and separating individual subpopulations from heterogeneous mixtures of cells. Flow cytometry uses fluorescent antibodies to label and sort the cells of interest, while centrifugal elutriation utilizes counterbalanced centrifugal and fluid flow forces to separate cells by size. In combination with two analytical procedures (premature chromosome condensation (PCC) and alkaline elution), these two techniques have been applied to study radiation effects on mononuclear cells from mouse peripheral blood irradiated in vivo, and cell cycle phase specific repair of single-strand breaks in cellular deoxyribonucleic acid (DNA) of the Chinese hamster ovary (CHO) fibroblast cell line irradiated in vitro.

  9. Selecting a radiation tolerant piezoelectric material for nuclear reactor applications

    NASA Astrophysics Data System (ADS)

    Parks, D. A.; Reinhardt, B. T.; Tittmann, B. R.

    2013-01-01

    Bringing systems for online monitoring of nuclear reactors to fruition has been delayed by the lack of suitable ultrasonic sensors. Recent work has demonstrated the capability of an AlN sensor to perform ultrasonic evaluation in an actual nuclear reactor. Although the AlN demonstrated sustainability, no loss in signal amplitude and d33 up to a fast and thermal neutron fluence of 1.85×1018 n/cm2 and 5.8×1018 n/cm2 respectively, no formal process to selecting a suitable sensor material was made. It would be ideal to use first principles approaches to somehow reduce each candidate piezoelectric material to a simple ranking showing directly which materials one should expect to be most radiation tolerant. However, the complexity of the problem makes such a ranking impractical and one must appeal to experimental observations. This should not be of any surprise to one whom is familiar with material science as most material properties are obtained in this manner. Therefore, this work adopts a similar approach, the mechanisms affecting radiation tolerance are discussed and a good engineering sense is used for material qualification of the candidate piezoelectric materials.

  10. Selecting a radiation tolerant piezoelectric material for nuclear reactor applications

    SciTech Connect

    Parks, D. A.; Reinhardt, B. T.; Tittmann, B. R.

    2013-01-25

    Bringing systems for online monitoring of nuclear reactors to fruition has been delayed by the lack of suitable ultrasonic sensors. Recent work has demonstrated the capability of an AlN sensor to perform ultrasonic evaluation in an actual nuclear reactor. Although the AlN demonstrated sustainability, no loss in signal amplitude and d{sub 33} up to a fast and thermal neutron fluence of 1.85 Multiplication-Sign 1018 n/cm{sup 2} and 5.8 Multiplication-Sign 1018 n/cm{sup 2} respectively, no formal process to selecting a suitable sensor material was made. It would be ideal to use first principles approaches to somehow reduce each candidate piezoelectric material to a simple ranking showing directly which materials one should expect to be most radiation tolerant. However, the complexity of the problem makes such a ranking impractical and one must appeal to experimental observations. This should not be of any surprise to one whom is familiar with material science as most material properties are obtained in this manner. Therefore, this work adopts a similar approach, the mechanisms affecting radiation tolerance are discussed and a good engineering sense is used for material qualification of the candidate piezoelectric materials.

  11. Global Impacts of Gas-Phase Chemistry-Aerosol Interactions on Direct Radiative Forcing by Anthropogenic Aerosols and Ozone

    NASA Technical Reports Server (NTRS)

    Liao, Hong; Seinfeld, John H.

    2005-01-01

    We present here a first global modeling study on the influence of gas-phase chemistry/aerosol interactions on estimates of anthropogenic forcing by tropospheric O3 and aerosols. Concentrations of gas-phase species and sulfate, nitrate, ammonium, black carbon, primary organic carbon, secondary organic carbon, sea salt, and mineral dust aerosols in the preindustrial, present-day, and year 2100 (IPCC SRES A2) atmospheres are simulated online in the Goddard Institute for Space Studies general circulation model II' (GISS GCM II'). With fully coupled chemistry and aerosols, the preindustrial, presentday, and year 2100 global burdens of tropospheric ozone are predicted to be 190, 319, and 519 Tg, respectively. The burdens of sulfate, nitrate, black carbon, and organic carbon are predicted respectively to be 0.32. 0.18, 0.01, 0.33 Tg in preindustrial time, 1.40, 0.48, 0.23, 1.60 Tg in presentday, and 1.37, 1.97, 0.54, 3.31 Tg in year 2100. Anthropogenic O3 is predicted to have a globally and annually averaged present-day forcing of +0.22 W m(sup -2) and year 2100 forcing of +0.57 W m(sup -2) at the top of the atmosphere (TOA). Net anthropogenic TOA forcing by internally mixed sulfate, nitrate, organic carbon, and black carbon aerosols is estimated to be virtually zero in the present-day and +0.34 W m(sup -2) in year 2100, whereas it is predicted to be -0.39 W m(sup -2) in present-day and -0.61 W m(sup -2) in year 2100 if the aerosols are externally mixed. Heterogeneous reactions are shown to be important in affecting anthropogenic forcing. When reactions of N2O5, NO3, NO2, and HO2 on aerosols are accounted for, TOA anthropogenic O3 forcing is less by 20-45% in present-day and by 20-32% in year 2100 at mid to high latitudes in the Northern Hemisphere, as compared with values predicted in the absence of heterogeneous gas aerosol reactions. Mineral dust uptake of HNO3 and O3 is shown to have practically no influence on anthropogenic O3 forcing. Heterogeneous reactions of N2Os

  12. Chemical Preconversion: Application of Low-Severity Pretreatment Chemistries for Commoditization of Lignocellulosic Feedstock

    SciTech Connect

    David N. Thompson; Timothy Campbell; Bryan Bals; Troy Runge; Farzaneh Teymouri

    2013-05-01

    Securing biofuels project financing is challenging, in part because of risks in feedstock supply. Commoditization of the feedstock and decoupling its supply from the biorefinery will promote greater economies of scale, reduce feedstock supply risk and reduce the need for overdesign of biorefinery pretreatment technologies. We present benefits and detractions of applying low-severity chemical treatments or ‘chemical preconversion treatments’ to enable this approach through feedstock modification and densification early in the supply chain. General structural modifications to biomass that support cost-effective densification and transportation are presented, followed by available chemistries to achieve these modifications with minimal yield loss and the potential for harvesting value in local economies. A brief review of existing biomass pretreatment technologies for cellulolytic hydrolysis at biorefineries is presented, followed by a discussion toward economically applying the underlying chemistries at reduced severity in light of capital and operational limitations of small-scale feedstock depots.

  13. Ubiquitous trisulfur radical anion: fundamentals and applications in materials science, electrochemistry, analytical chemistry and geochemistry.

    PubMed

    Chivers, Tristram; Elder, Philip J W

    2013-07-21

    The trisulfur radical anion [S3]˙(-) is well-known from inorganic chemistry textbooks as the blue chromophore in ultramarine blues in which this highly reactive species is trapped in a zeolitic framework. Recent findings have revealed that [S3]˙(-) has a multi-faceted role in a variety of media, including alkali metal-sulfur batteries, aqueous solutions at high temperatures and pressures, and ionic liquids; it has also been used to detect trace amounts of water in organic solvents. This tutorial review illustrates how various physical techniques are used to identify a reactive species in solution and shows how elucidation of electronic structures can be used to explain spectroscopic and structural properties. Examples of the function of [S3]˙(-) in materials science, electrochemistry, analytical chemistry and geochemistry are used to illustrate the widespread influence of this fundamentally important triatomic sulfur species.

  14. Immersive virtual reality in computational chemistry: Applications to the analysis of QM and MM data

    PubMed Central

    Salvadori, Andrea; Del Frate, Gianluca; Pagliai, Marco; Barone, Vincenzo

    2016-01-01

    Abstract The role of Virtual Reality (VR) tools in molecular sciences is analyzed in this contribution through the presentation of the Caffeine software to the quantum chemistry community. Caffeine, developed at Scuola Normale Superiore, is specifically tailored for molecular representation and data visualization with VR systems, such as VR theaters and helmets. Usefulness and advantages that can be gained by exploiting VR are here reported, considering few examples specifically selected to illustrate different level of theory and molecular representation. PMID:27867214

  15. Open, Cross Platform Chemistry Application Unifying Structure Manipulation, External Tools, Databases and Visualization

    DTIC Science & Technology

    2012-11-27

    have been put in place for the projects: • Community website dedicated to Open Chemistry projects • Git source code repositories (Kitware, mirrored...A10-110 Proposal A2-4714 Kitware, Inc. The Gerrit code review system,[12] developed by Google as an open - source project for the Android operating...with nightly software build testing on all three major platforms for merged code and testing of proposed changes using CDash@Home[13] (an open - source

  16. Radiation from plutonium 238 used in space applications

    NASA Technical Reports Server (NTRS)

    Keenan, T. K.; Vallee, R. E.; Powers, J. A.

    1972-01-01

    The principal mode of the nuclear decay of plutonium 238 is by alpha particle emission at a rate of 17 curies per gram. Gamma radiation also present in nuclear fuels arises primarily from the nuclear de-excitation of daughter nuclei as a result of the alpha decay of plutonium 238 and reactor-produced impurities. Plutonium 238 has a spontaneous fission half life of 4.8 x 10 to the 10th power years. Neutrons associated with this spontaneous fission are emitted at a rate of 28,000 neutrons per second per gram. Since the space fuel form of plutonium 238 is the oxide pressed into a cermet with molybdenum, a contribution to the neutron emission rate arises from (alpha, n) reactions with 0-17 and 0-18 which occur in natural oxygen.

  17. Image Guidance in Radiation Therapy: Techniques and Applications

    PubMed Central

    Kataria, Tejinder

    2014-01-01

    In modern day radiotherapy, the emphasis on reduction on volume exposed to high radiotherapy doses, improving treatment precision as well as reducing radiation-related normal tissue toxicity has increased, and thus there is greater importance given to accurate position verification and correction before delivering radiotherapy. At present, several techniques that accomplish these goals impeccably have been developed, though all of them have their limitations. There is no single method available that eliminates treatment-related uncertainties without considerably adding to the cost. However, delivering “high precision radiotherapy” without periodic image guidance would do more harm than treating large volumes to compensate for setup errors. In the present review, we discuss the concept of image guidance in radiotherapy, the current techniques available, and their expected benefits and pitfalls. PMID:25587445

  18. Nuclear data needed for applications in radiation oncology

    SciTech Connect

    White, R.M.; Chadwick, M.B.; Siantar, C.L.H.; Chandler, W.P.

    1994-03-01

    Fast neutrons have been used to treat over 15,000 cancer patients in approximately twenty centers worldwide and proton therapy is emerging as a potential treatment of choice for tumors near critical anatomical structures. Neutron therapy requires reaction data to {approximately}70 MeV while proton therapy requires data to {approximately}250 MeV. The cross section databases require energy- and angle-dependent cross sections for secondary neutrons, charged-particles and recoil nuclei. We discuss expansion of our nuclear databases and development of a three-dimensional radiation transport package that uses CT images as the input mesh to an all-particle Monte Carlo code. Called PEREGRINE, this code calculates dose distributions in the human body and can be used as a tool to determine the dependence of dose on details of the evaluated nuclear data.

  19. Evaluation and applicability of transfinite element formulations with particular reference to radiation

    NASA Technical Reports Server (NTRS)

    Tamma, Kumar K.; Railkar, Sudhir B.

    1988-01-01

    The evaluation and applicability of hybrid transfinite element formulations are described for transient nonlinear thermal models with particular reference to account for radiation effects. The formulations are developed from basic concepts and evaluated for both one- and two-dimensional thermal models. The methodology presented is a hybrid approach as it combines finite elements, classical Galerkin schemes, and transform methods. Basic features of the hybrid formulations and the associated solution scheme used are first described. Therein, numerical test models are presented to evaluate the applicability for predicting the nonlinear transient response in one- and two-dimensional thermal models influenced due to radiation effects.

  20. E-Licensing of Radiation Applications (eLORA) in Armed Forces Hospitals: 'Nuts and Bolts'.

    PubMed

    Aggarwal, Rohit; George, R A; Alam, Aftab; Soni, B K

    2017-01-01

    As per current statutory requirement, licence for operation of all medical radiation facilities (diagnostic radiology/radiotherapy/nuclear medicine) in India has to be obtained using the e-Licensing of Radiation Applications (acronym as 'eLORA') platform which is a web-based application on Atomic Energy Regulatory Board (AERB) website. This article is envisaged as a procedural guide for all medical administrators and radiologists in service institutions processing eLORA. Specific focus has been placed on practical methods to deal with inherent procedural hurdles unique to armed forces institutions, based on first-hand experience gained in successful eLORA processing at a tertiary care hospital.

  1. A three-dimensional chemistry/general circulation model simulation of anthropogenically derived ozone in the troposphere and its radiative climate forcing

    NASA Astrophysics Data System (ADS)

    Roelofs, Geert-Jan; Lelieveld, Jos; van Dorland, Rob

    1997-10-01

    We present results from the tropospheric chemistry/climate European Center Hamburg Model by comparing two simulations that consider a preindustrial and a contemporary emission scenario. Photochemical O3 production from anthropogenically emitted precursors contributes about 30% to the present-day tropospheric O3 content, which is roughly equal to the natural photochemical production. Transports of stratospheric O3 into the troposphere contribute about 40%. As a result of anthropogenic emissions, the O3 maximum over remote northern hemisphere (NH) areas has shifted from winter to spring, when photochemical production of O3 is relatively efficient. Over NH continents the preindustrial seasonal variability is relatively weak whereas a distinct surface O3 summer maximum appears in the contemporary simulation. In the (sub)tropical southern hemisphere (SH), anthropogenic biomass burning emissions cause an increase of O3 mixing ratios in the dry season (September-November). We calculate a relative increase in O3 mixing ratios due to anthropogenic emissions of about 30% in the pristine SH middle and high latitudes to about 100% in the polluted NH boundary layer. The model simulations suggest that the absolute increase of tropospheric O3 maximizes in the middle troposphere. Through convection, upper tropospheric O3 mixing ratios are significantly affected in the tropical regions and, during summer, in the middle and high NH latitudes. Under these conditions the radiative forcing of climate by increasing O3 is relatively large. We calculate a global and annual average radiative forcing by tropospheric O3 perturbations of 0.42 W m-2, i.e., 0.51 W m-2 in the NH and 0.33 W m-2 in the SH.

  2. Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

    NASA Astrophysics Data System (ADS)

    Mallet, M.; Dulac, F.; Formenti, P.; Nabat, P.; Sciare, J.; Roberts, G.; Pelon, J.; Ancellet, G.; Tanré, D.; Parol, F.; Denjean, C.; Brogniez, G.; di Sarra, A.; Alados-Arboledas, L.; Arndt, J.; Auriol, F.; Blarel, L.; Bourrianne, T.; Chazette, P.; Chevaillier, S.; Claeys, M.; D'Anna, B.; Derimian, Y.; Desboeufs, K.; Di Iorio, T.; Doussin, J.-F.; Durand, P.; Féron, A.; Freney, E.; Gaimoz, C.; Goloub, P.; Gómez-Amo, J. L.; Granados-Muñoz, M. J.; Grand, N.; Hamonou, E.; Jankowiak, I.; Jeannot, M.; Léon, J.-F.; Maillé, M.; Mailler, S.; Meloni, D.; Menut, L.; Momboisse, G.; Nicolas, J.; Podvin, T.; Pont, V.; Rea, G.; Renard, J.-B.; Roblou, L.; Schepanski, K.; Schwarzenboeck, A.; Sellegri, K.; Sicard, M.; Solmon, F.; Somot, S.; Torres, B.; Totems, J.; Triquet, S.; Verdier, N.; Verwaerde, C.; Waquet, F.; Wenger, J.; Zapf, P.

    2016-01-01

    The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental setup also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote-sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modeling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to producing high

  3. Chemical and radiation crosslinked polymer electrolyte membranes prepared from radiation-grafted ETFE films for DMFC applications

    NASA Astrophysics Data System (ADS)

    Chen, Jinhua; Asano, Masaharu; Yamaki, Tetsuya; Yoshida, Masaru

    To develop a highly chemically stable polymer electrolyte membrane for application in a direct methanol fuel cell (DMFC), doubly crosslinked membranes were prepared by chemical crosslinking using bifunctional monomers, such as divinylbenzene (DVB) and bis(p, p-vinyl phenyl) ethane (BVPE), and by radiation crosslinking. The membranes were prepared by grafting of m, p-methylstyrene (MeSt) and p-tert-butylstyrene (tBuSt) into poly(ethylene- co-tetrafluoroethylene) (ETFE) films and subsequent sulfonation. The effects of the DVB and BVPE crosslinkers on the grafting kinetics and the properties of the prepared membranes, such as water uptake, proton conductivity and chemical stability were investigated. Radiation crosslinking was introduced by irradiation of the ETFE base film, the grafted film or the sulfonated membrane. The membrane crosslinked by DVB and BVPE crosslinkers and post-crosslinked by γ-ray irradiation of the corresponding grafted film possessed the highest chemical stability among the prepared membranes, a significantly lower methanol permeability compared to Nafion ® membranes, and a better DMFC performance for high methanol feed concentration. Therefore, this doubly crosslinked membrane was promising for application in a DMFC where relatively high methanol concentration could be fed.

  4. A Component Approach to Collaborative Scientific Software Development: Tools and Techniques Utilized by the Quantum Chemistry Science Application Partnership

    DOE PAGES

    Kenny, Joseph P.; Janssen, Curtis L.; Gordon, Mark S.; ...

    2008-01-01

    Cutting-edge scientific computing software is complex, increasingly involving the coupling of multiple packages to combine advanced algorithms or simulations at multiple physical scales. Component-based software engineering (CBSE) has been advanced as a technique for managing this complexity, and complex component applications have been created in the quantum chemistry domain, as well as several other simulation areas, using the component model advocated by the Common Component Architecture (CCA) Forum. While programming models do indeed enable sound software engineering practices, the selection of programming model is just one building block in a comprehensive approach to large-scale collaborative development which must also addressmore » interface and data standardization, and language and package interoperability. We provide an overview of the development approach utilized within the Quantum Chemistry Science Application Partnership, identifying design challenges, describing the techniques which we have adopted to address these challenges and highlighting the advantages which the CCA approach offers for collaborative development.« less

  5. Some current advances in biophysical applications of ionizing radiation for health preservation

    NASA Astrophysics Data System (ADS)

    Watt, D. E.

    1987-03-01

    Radiation Physics is a subject of major importance in application to health preservation through investigative, diagnostic, analytical and therapeutic procedures for clinical purposes. Its benefits are enormous and well-established. However there are also hazards and so it is important for health preservation purposes to establish quantitatively the degree of risk undergone by persons exposed to radiation in the natural environment, in their occupations and in medical treatment. In this paper a brief indication is given of the extensive utilisation of the unique properties of radiation in biomedical application. This is followed by fuller discussion on new developments in our understanding of radiation damage mechanisms in radiotherapy and radiological protection. An example is given in biomedical research into the role of trace elements in gallstone formation using neutron activation anaysis, proton induced X-ray emission and X-ray fluorescence analysis as complementary techniques for maximising sensitivity in multielemental analysis by induced radiation. Procedures are described for measuring radiation effect, at bone/ tissue and lung/air interfaces, due to the uptake of radioactive material from the natural environment. Finally a topical subject in nuclear medicine viz. the possible advantages and hazards of Auger electron cascades resulting from inner shell vacancies in electron capture nuclides, is examined in the light of new evidence.

  6. Exploring the limitations of the Hantzsch method used for quantification of hydroxyl radicals in systems of relevance for interfacial radiation chemistry

    NASA Astrophysics Data System (ADS)

    Yang, Miao; Soroka, Inna; Jonsson, Mats

    2017-01-01

    In the presence of Tris or methanol, hydroxyl radicals in systems of relevance for interfacial radiation chemistry can be quantified indirectly via the Hantzsch method by determining the amount of the scavenging product formaldehyde formed. In this work, the influence of the presence of H2O2 on the Hantzsch method using acetoacetanilide (AAA) as derivatization reagent is studied. The experiments show that the measured CH2O concentration deviates from the actual concentration in the presence of H2O2 and the deviation increases with increasing [H2O2]0/[CH2O]0. The deviation is negative, i.e., the measured formaldehyde concentration is lower than the actual concentration. This leads to an underestimation of the hydroxyl radical production in systems containing significant amount of H2O2. The main reason for the deviation is found to be three coupled equilibria involving H2O2, CH2O and the derivative produced in the Hantzsch method.

  7. The radiation induced chemistry of uranyl cation in aqueous carbonate –bicarbonate solutions as followed by NMR spectroscopy

    SciTech Connect

    McNamara, Bruce K.; Snow, Lanee A.; Soderquist, Chuck Z.; Sinkov, Sergei I.; Cho, Herman M.; Friese, Judah I.

    2006-05-01

    Alpha radiation induced formation of hydrogen peroxide in carbonate ?bicarbonate media was followed by 13C NMR using dissolved [233UO2(13CO3)3]4- as the alpha source (Dalpha= 12.1 Gy/hr). Between the pH region between 5.9 and 11.6 hydrogen peroxide causes a varied speciation of the uranyl carbonates that is a function of the uranium, carbonate and the hydrogen peroxide concentrations. It is shown that the speciation of the peroxy carbonates (or other species) formed in solution by titration with hydrogen peroxide are common to those formed by hydrogen peroxide generated by radiolysis. The radiolysis experiment was carried out above pH = 9.96 to minimize the loss of 13CO2 over a 2800 hr period. Radiolytic generation of hydrogen peroxide was followed by formation of a uranyl peroxy carbonate complex and complex formation accelerated for about 1200 hours. Complex formation was observed to terminate at a concentration between 1x10-4 and 5x10-4 M. It is assumed that either a steady state H2O2 production rate was established in solution or that some limiting feature of the experiment was responsible for slowing the yield of product.

  8. ULTROX INTERNATIONAL ULTRAVIOLET RADIATION/OXIDATION TECHNOLOGY APPLICATIONS ANALYSIS REPORT

    EPA Science Inventory

    In support of the U.S. Environmental Protection Agency’s (EPA) Superfund Innovative Technology Evaluation (SITE) Program, this report evaluates the Ultrox International technology and its applicability as an on-site treatment method for contaminated groundwater. The ULTROX® techn...

  9. 2-Methyltetrahydrofuran (2-MeTHF): a biomass-derived solvent with broad application in organic chemistry.

    PubMed

    Pace, Vittorio; Hoyos, Pilar; Castoldi, Laura; Domínguez de María, Pablo; Alcántara, Andrés R

    2012-08-01

    2-Methyl-tetrahydrofuran (2-MeTHF) can be derived from renewable resources (e.g., furfural or levulinic acid) and is a promising alternative solvent in the search for environmentally benign synthesis strategies. Its physical and chemical properties, such as its low miscibility with water, boiling point, remarkable stability compared to other cyclic-based solvents such as THF, and others make it appealing for applications in syntheses involving organometallics, organocatalysis, and biotransformations or for processing lignocellulosic materials. Interestingly, a significant number of industries have also started to assess 2-MeTHF in several synthetic procedures, often with excellent results and prospects. Likewise, preliminary toxicology assessments suggest that the use of 2-MeTHF might even be extended to more processes in pharmaceutical chemistry. This Minireview describes the properties of 2-MeTHF, the state-of-the-art of its use in synthesis, and covers several outstanding examples of its application from both industry and academia.

  10. Monte Carlo track structure for radiation biology and space applications

    NASA Technical Reports Server (NTRS)

    Nikjoo, H.; Uehara, S.; Khvostunov, I. G.; Cucinotta, F. A.; Wilson, W. E.; Goodhead, D. T.

    2001-01-01

    Over the past two decades event by event Monte Carlo track structure codes have increasingly been used for biophysical modelling and radiotherapy. Advent of these codes has helped to shed light on many aspects of microdosimetry and mechanism of damage by ionising radiation in the cell. These codes have continuously been modified to include new improved cross sections and computational techniques. This paper provides a summary of input data for ionizations, excitations and elastic scattering cross sections for event by event Monte Carlo track structure simulations for electrons and ions in the form of parametric equations, which makes it easy to reproduce the data. Stopping power and radial distribution of dose are presented for ions and compared with experimental data. A model is described for simulation of full slowing down of proton tracks in water in the range 1 keV to 1 MeV. Modelling and calculations are presented for the response of a TEPC proportional counter irradiated with 5 MeV alpha-particles. Distributions are presented for the wall and wall-less counters. Data shows contribution of indirect effects to the lineal energy distribution for the wall counters responses even at such a low ion energy.

  11. Radiation belt measurements strategy for space weather applications

    NASA Astrophysics Data System (ADS)

    Bourdarie, Sebastien; Maget, Vincent; Lazaro, Didier; Daglis, Yannis; Sandberg, Ingmar

    2015-04-01

    In the framework of the EU-FP7 MAARBLE project, the Salammbô code and an ensemble Kalman filter is being used to reproduce the electron radiation belt dynamics during storms. One of the most widely used and reliable methods of assessing a data assimilation scheme is that of the twin experiments. The identical-twin experiments consist in a numerical procedure where synthetic data can be generated by the model to which data assimilation is applied, subject to a specified stochastic forcing term. The data with assigned errors are then evaluated for their effectiveness in obtaining optimal state estimates. The convergence of the unassimilated model fields from the second run towards those of the first run ("true" state) can then be measured. This set up is used here to define what is the minimum data required and along which orbits to still ensure a good estimate of the true state. The number of data being assimilated (cadence as well as distinct orbits) will be considered as a parameter such as to check data assimilation tool performance in each case. This analysis will be very useful in the case of optimizing a space surveillance system for ionizing particles. MAARBLE has received fundings from the European Community's Seventh Framework Programme (FP7-SPACE-.2010-1, SP1 Cooperation, Collaborative project) under grant agreement n284520. This paper reflects only the authors' views and the European Union is not liable for any use that may be made of the information contained therein.

  12. APPLICATION OF JITTER RADIATION: GAMMA-RAY BURST PROMPT POLARIZATION

    SciTech Connect

    Mao, Jirong; Wang, Jiancheng

    2013-10-10

    A high degree of polarization of gamma-ray burst (GRB) prompt emission has been confirmed in recent years. In this paper, we apply jitter radiation to study the polarization feature of GRB prompt emission. In our framework, relativistic electrons are accelerated by turbulent acceleration. Random and small-scale magnetic fields are generated by turbulence. We further determine that the polarization property of GRB prompt emission is governed by the configuration of the random and small-scale magnetic fields. A two-dimensional compressed slab, which contains a stochastic magnetic field, is applied in our model. If the jitter condition is satisfied, the electron deflection angle in the magnetic field is very small and the electron trajectory can be treated as a straight line. A high degree of polarization can be achieved when the angle between the line of sight and the slab plane is small. Moreover, micro-emitters with mini-jet structures are considered to be within a bulk GRB jet. The jet 'off-axis' effect is intensely sensitive to the observed polarization degree. We discuss the depolarization effect on GRB prompt emission and afterglow. We also speculate that the rapid variability of GRB prompt polarization may be correlated with the stochastic variability of the turbulent dynamo or the magnetic reconnection of plasmas.

  13. An inverse source location algorithm for radiation portal monitor applications

    SciTech Connect

    Miller, Karen A; Charlton, William S

    2010-01-01

    Radiation portal monitors are being deployed at border crossings throughout the world to prevent the smuggling of nuclear and radiological materials; however, a tension exists between security and the free-flow of commerce. Delays at ports-of-entry have major economic implications, so it is imperative to minimize portal monitor screening time. We have developed an algorithm to locate a radioactive source using a distributed array of detectors, specifically for use at border crossings. To locate the source, we formulated an optimization problem where the objective function describes the least-squares difference between the actual and predicted detector measurements. The predicted measurements are calculated by solving the 3-D deterministic neutron transport equation given an estimated source position. The source position is updated using the steepest descent method, where the gradient of the objective function with respect to the source position is calculated using adjoint transport calculations. If the objective function is smaller than the convergence criterion, then the source position has been identified. This paper presents the derivation of the underlying equations in the algorithm as well as several computational test cases used to characterize its accuracy.

  14. A Fast All-sky Radiation Model for Solar applications (FARMS): Algorithm and performance evaluation

    SciTech Connect

    Xie, Yu; Sengupta, Manajit; Dudhia, Jimy

    2016-10-01

    Radiative transfer (RT) models simulating broadband solar radiation have been widely used by atmospheric scientists to model solar resources for various energy applications such as operational forecasting. Due to the complexity of solving the RT equation, the computation under cloudy conditions can be extremely time-consuming, though many approximations (e.g., two-stream approach and delta-M truncation scheme) have been utilized. Thus, a more efficient RT model is crucial for model developers as a new option for approximating solar radiation at the land surface with minimal loss of accuracy. In this study, we developed a fast all-sky radiation model for solar applications (FARMS) using the simplified clear-sky RT model, REST2, and simulated cloud transmittances and reflectances from the Rapid Radiation Transfer Model (RRTM) with a 16-stream Discrete Ordinates Radiative Transfer (DISORT). Simulated lookup tables (LUTs) of cloud transmittances and reflectances are created by varying cloud optical thicknesses, cloud particle sizes, and solar zenith angles. Equations with optimized parameters are fitted to the cloud transmittances and reflectances to develop the model. The all-sky solar irradiance at the land surface can then be computed rapidly by combining REST2 with the cloud transmittances and reflectances. This new RT model is more than 1,000 times faster than those currently utilized in solar resource assessment and forecasting because it does not explicitly solve the RT equation for each individual cloud condition. Our results indicate that the accuracy of the fast radiative transfer model is comparable to or better than two-stream approximation in term of computing cloud transmittance and solar radiation.

  15. A new hybrid transfinite element computational methodology for applicability to conduction/convection/radiation heat transfer

    NASA Technical Reports Server (NTRS)

    Tamma, Kumar K.; Railkar, Sudhir B.

    1988-01-01

    This paper describes new and recent advances in the development of a hybrid transfinite element computational methodology for applicability to conduction/convection/radiation heat transfer problems. The transfinite element methodology, while retaining the modeling versatility of contemporary finite element formulations, is based on application of transform techniques in conjunction with classical Galerkin schemes and is a hybrid approach. The purpose of this paper is to provide a viable hybrid computational methodology for applicability to general transient thermal analysis. Highlights and features of the methodology are described and developed via generalized formulations and applications to several test problems. The proposed transfinite element methodology successfully provides a viable computational approach and numerical test problems validate the proposed developments for conduction/convection/radiation thermal analysis.

  16. Final report on LDRD project 52722 : radiation hardened optoelectronic components for space-based applications.

    SciTech Connect

    Hargett, Terry W.; Serkland, Darwin Keith; Blansett, Ethan L.; Geib, Kent Martin; Sullivan, Charles Thomas; Hawkins, Samuel D.; Wrobel, Theodore Frank; Keeler, Gordon Arthur; Klem, John Frederick; Medrano, Melissa R.; Peake, Gregory Merwin; Karpen, Gary D.; Montano, Victoria A.

    2003-12-01

    This report describes the research accomplishments achieved under the LDRD Project 'Radiation Hardened Optoelectronic Components for Space-Based Applications.' The aim of this LDRD has been to investigate the radiation hardness of vertical-cavity surface-emitting lasers (VCSELs) and photodiodes by looking at both the effects of total dose and of single-event upsets on the electrical and optical characteristics of VCSELs and photodiodes. These investigations were intended to provide guidance for the eventual integration of radiation hardened VCSELs and photodiodes with rad-hard driver and receiver electronics from an external vendor for space applications. During this one-year project, we have fabricated GaAs-based VCSELs and photodiodes, investigated ionization-induced transient effects due to high-energy protons, and measured the degradation of performance from both high-energy protons and neutrons.

  17. Optical diagnostic and therapy applications of femtosecond laser radiation using lens-axicon focusing.

    PubMed

    Parigger, Christian G; Johnson, Jacqueline A; Splinter, Robert

    2013-01-01

    Diagnostic modalities by means of optical and/or near infrared femtosecond radiation through biological media can in principle be adapted to therapeutic applications. Of specific interest are soft tissue diagnostics and subsequent therapy through hard tissue such as bone. Femto-second laser pulses are delivered to hydroxyapatite representing bone, and photo-acoustic spectroscopy is presented in order to identify the location of optical anomalies in an otherwise homogeneous medium. Imaging through bone is being considered for diagnostic, and potentially therapeutic, applications related to brain tumors. The use of mesomeric optics such as lens-axicon combinations is of interest to achieve the favorable distribution of focused radiation. Direct therapy by increasing local temperature to induce hyperthermia is one mode of brain tumor therapy. This can be enhanced by seeding the tumor with nanoparticles. Opto-acoustic imaging using femtosecond laser radiation is a further opportunity for diagnosis.

  18. Non-Destructive Evaluation (NDE) Applications of THz Radiation

    NASA Astrophysics Data System (ADS)

    Zimdars, David

    2005-03-01

    The technology and applications of time domain terahertz (THz) imaging to non-destructive evaluation (NDE) will be discussed. THz imaging has shown great promise in 2 and 3 dimensional non-contact inspection of non-conductive materials such as plastics, foam, composites, ceramics, paper, wood and glass. THz imaging employs safe low power non-ionizing electromagnetic pulses, with lateral resolution < 200 um, and depth resolution < 50 um. THz pulses can be analyzed spectroscopically to reveal chemical content. Recently, highly integrated turn-key THz imaging systems have been introduced commercially. We will demonstrate the detection of voids and disbonds intentionally incorporated within the sprayed on foam insulation of a space shuttle external tank mock-up segments. An industrially hardened THz scanning system which has been deployed to scan the space shuttle tank with small remote transceiver will be described. Additional terahertz security imaging applications for the detection of weapons and explosives will also be discussed, as well as the application of terahertz sensors for high speed industrial process monitoring and quality control.

  19. Molecular dynamics for irradiation driven chemistry: application to the FEBID process*

    NASA Astrophysics Data System (ADS)

    Sushko, Gennady B.; Solov'yov, Ilia A.; Solov'yov, Andrey V.

    2016-10-01

    A new molecular dynamics (MD) approach for computer simulations of irradiation driven chemical transformations of complex molecular systems is suggested. The approach is based on the fact that irradiation induced quantum transformations can often be treated as random, fast and local processes involving small molecules or molecular fragments. We advocate that the quantum transformations, such as molecular bond breaks, creation and annihilation of dangling bonds, electronic charge redistributions, changes in molecular topologies, etc., could be incorporated locally into the molecular force fields that describe the classical MD of complex molecular systems under irradiation. The proposed irradiation driven molecular dynamics (IDMD) methodology is designed for the molecular level description of the irradiation driven chemistry. The IDMD approach is implemented into the MBN Explorer software package capable to operate with a large library of classical potentials, many-body force fields and their combinations. IDMD opens a broad range of possibilities for modelling of irradiation driven modifications and chemistry of complex molecular systems ranging from radiotherapy cancer treatments to the modern technologies such as focused electron beam deposition (FEBID). As an example, the new methodology is applied for studying the irradiation driven chemistry caused by FEBID of tungsten hexacarbonyl W(CO)6 precursor molecules on a hydroxylated SiO2 surface. It is demonstrated that knowing the interaction parameters for the fragments of the molecular system arising in the course of irradiation one can reproduce reasonably well experimental observations and make predictions about the morphology and molecular composition of nanostructures that emerge on the surface during the FEBID process.

  20. Integrative Biological Chemistry Program Includes The Use Of Informatics Tools, GIS And SAS Software Applications

    PubMed Central

    D’Souza, Malcolm J.; Kashmar, Richard J.; Hurst, Kent; Fiedler, Frank; Gross, Catherine E.; Deol, Jasbir K.; Wilson, Alora

    2015-01-01

    Wesley College is a private, primarily undergraduate minority-serving institution located in the historic district of Dover, Delaware (DE). The College recently revised its baccalaureate biological chemistry program requirements to include a one-semester Physical Chemistry for the Life Sciences course and project-based experiential learning courses using instrumentation, data-collection, data-storage, statistical-modeling analysis, visualization, and computational techniques. In this revised curriculum, students begin with a traditional set of biology, chemistry, physics, and mathematics major core-requirements, a geographic information systems (GIS) course, a choice of an instrumental analysis course or a statistical analysis systems (SAS) programming course, and then, students can add major-electives that further add depth and value to their future post-graduate specialty areas. Open-sourced georeferenced census, health and health disparity data were coupled with GIS and SAS tools, in a public health surveillance system project, based on US county zip-codes, to develop use-cases for chronic adult obesity where income, poverty status, health insurance coverage, education, and age were categorical variables. Across the 48 contiguous states, obesity rates are found to be directly proportional to high poverty and inversely proportional to median income and educational achievement. For the State of Delaware, age and educational attainment were found to be limiting obesity risk-factors in its adult population. Furthermore, the 2004–2010 obesity trends showed that for two of the less densely populated Delaware counties; Sussex and Kent, the rates of adult obesity were found to be progressing at much higher proportions when compared to the national average. PMID:26191337

  1. Experimental studies of lithium-based surface chemistry for fusion plasma-facing materials applications

    NASA Astrophysics Data System (ADS)

    Allain, J. P.; Rokusek, D. L.; Harilal, S. S.; Nieto-Perez, M.; Skinner, C. H.; Kugel, H. W.; Heim, B.; Kaita, R.; Majeski, R.

    2009-06-01

    Lithium has enhanced the operational performance of fusion devices such as: TFTR, CDX-U, FTU, T-11 M, and NSTX. Lithium in the solid and liquid state has been studied extensively in laboratory experiments including its erosion and hydrogen-retaining properties. Reductions in physical sputtering up to 40-60% have been measured for deuterated solid and liquid lithium surfaces. Computational modeling indicates that up to a 1:1 deuterium volumetric retention in lithium is possible. This paper presents the results of systematic in situ laboratory experimental studies on the surface chemistry evolution of ATJ graphite under lithium deposition. Results are compared to post-mortem analysis of similar lithium surface coatings on graphite exposed to deuterium discharge plasmas in NSTX. Lithium coatings on plasma-facing components in NSTX have shown substantial reduction of hydrogenic recycling. Questions remain on the role lithium surface chemistry on a graphite substrate has on particle sputtering (physical and chemical) as well as hydrogen isotope recycling. This is particularly due to the lack of in situ measurements of plasma-surface interactions in tokamaks such as NSTX. Results suggest that the lithium bonding state on ATJ graphite is lithium peroxide and with sufficient exposure to ambient air conditions, lithium carbonate is generated. Correlation between both results is used to assess the role of lithium chemistry on the state of lithium bonding and implications on hydrogen pumping and lithium sputtering. In addition, reduction of factors between 10 and 30 reduction in physical sputtering from lithiated graphite compared to pure lithium or carbon is also measured.

  2. Integrative Biological Chemistry Program Includes The Use Of Informatics Tools, GIS And SAS Software Applications.

    PubMed

    D'Souza, Malcolm J; Kashmar, Richard J; Hurst, Kent; Fiedler, Frank; Gross, Catherine E; Deol, Jasbir K; Wilson, Alora

    Wesley College is a private, primarily undergraduate minority-serving institution located in the historic district of Dover, Delaware (DE). The College recently revised its baccalaureate biological chemistry program requirements to include a one-semester Physical Chemistry for the Life Sciences course and project-based experiential learning courses using instrumentation, data-collection, data-storage, statistical-modeling analysis, visualization, and computational techniques. In this revised curriculum, students begin with a traditional set of biology, chemistry, physics, and mathematics major core-requirements, a geographic information systems (GIS) course, a choice of an instrumental analysis course or a statistical analysis systems (SAS) programming course, and then, students can add major-electives that further add depth and value to their future post-graduate specialty areas. Open-sourced georeferenced census, health and health disparity data were coupled with GIS and SAS tools, in a public health surveillance system project, based on US county zip-codes, to develop use-cases for chronic adult obesity where income, poverty status, health insurance coverage, education, and age were categorical variables. Across the 48 contiguous states, obesity rates are found to be directly proportional to high poverty and inversely proportional to median income and educational achievement. For the State of Delaware, age and educational attainment were found to be limiting obesity risk-factors in its adult population. Furthermore, the 2004-2010 obesity trends showed that for two of the less densely populated Delaware counties; Sussex and Kent, the rates of adult obesity were found to be progressing at much higher proportions when compared to the national average.

  3. Bioorganic and bioinorganic chemistry.

    PubMed

    Constable, Edwin C; Housecroft, Catherine E; Creus, Marc; Gademann, Karl; Giese, Bernd; Ward, Thomas R; Woggon, Wolf D; Chougnet, Antoinette

    2010-01-01

    The interdisciplinary projects in bioinorganic and bioorganic chemistry of the Department of Chemistry, University of Basel led to the preparation of new systems that mimic biologically important processes and to the discovery of compounds from natural sources which are very promising with respect to medical applications. The advances in these areas are reported here.

  4. Experience with the application of radiation protection standards: A driving force

    SciTech Connect

    Selby, J.M.; Swinth, K.L.; Vallario, E.J.

    1987-09-01

    This paper identifies the driving forces for the development of new standards within the radiation protection areas, characterizes the process of developing such guidance, discusses problems with the application of guidance and discusses experience in applying recommendations and standards. Efforts to improve performance in health physics measurements will also be described including methods to determine the feasibility and applicability of standards. 15 refs., 1 fig., 3 tabs.

  5. On the spectrum of radiation pressure driven optomechanical oscillator and its application in sensing

    NASA Astrophysics Data System (ADS)

    Liu, F.; Hossein-Zadeh, M.

    2013-05-01

    We study the RF spectrum of radiation pressure driven optomechanical oscillators (OMO). Using experiments and theoretical estimations we have characterized the relative amplitude of OMO's spectral components as a function of optical detuning and optical input power. We have identified a regime where the optical resonance shift can be directly extracted from the RF spectrum for resonant optical sensing applications.

  6. Application of thermoluminescence technique to identify radiation processed foods

    NASA Astrophysics Data System (ADS)

    Kiyak, N.

    1995-02-01

    Research studies reported by various authors have shown that a few methods one of which is thermoluminescence technique- may be suitable for identification of some certain irradiated spicies and food containing bones. This study is an application of the thermoluminescence technique for identifying the irradiated samples. The investigation was carried out on different types of foodstuffs such as onions, potatoes and kiwi. Measurements show that the technique can be applied as a reliable method to distinguish the irradiated food products from non-irradiated ones. The results demonstrate also that it is possible to use this method for determining the absorbed dose of irradiated samples from the established dose-effect curve.

  7. Pyranoside-into-furanoside rearrangement: new reaction in carbohydrate chemistry and its application in oligosaccharide synthesis.

    PubMed

    Krylov, Vadim B; Argunov, Dmitry A; Vinnitskiy, Dmitry Z; Verkhnyatskaya, Stella A; Gerbst, Alexey G; Ustyuzhanina, Nadezhda E; Dmitrenok, Andrey S; Huebner, Johannes; Holst, Otto; Siebert, Hans-Christian; Nifantiev, Nikolay E

    2014-12-08

    Great interest in natural furanoside-containing compounds has challenged the development of preparative methods for their synthesis. Herein a novel reaction in carbohydrate chemistry, namely a pyranoside-into-furanoside (PIF) rearrangement permitting the transformation of selectively O-substituted pyranosides into the corresponding furanosides is reported. The discovered process includes acid-promoted sulfation accompanied by rearrangement of the pyranoside ring into a furanoside ring followed by solvolytic O-desulfation. This process, which has no analogy in organic chemistry, was shown to be a very useful tool for the synthesis of furanoside-containing complex oligosaccharides, which was demonstrated by synthesizing disaccharide derivatives α-D-Galp-(1→3)-β-D-Galf-OPr, 3-O-s-lactyl-β-D-Galf-(1→3)-β-D-Glcp-OPr, and α-L-Fucf-(1→4)-β-D-GlcpA-OPr related to polysaccharides from the bacteria Klebsiella pneumoniae and Enterococcus faecalis and the brown seaweed Chordaria flagelliformis.

  8. Application of computer assisted combinatorial chemistry in antivirial, antimalarial and anticancer agents design

    NASA Astrophysics Data System (ADS)

    Burello, E.; Bologa, C.; Frecer, V.; Miertus, S.

    Combinatorial chemistry and technologies have been developed to a stage where synthetic schemes are available for generation of a large variety of organic molecules. The innovative concept of combinatorial design assumes that screening of a large and diverse library of compounds will increase the probability of finding an active analogue among the compounds tested. Since the rate at which libraries are screened for activity currently constitutes a limitation to the use of combinatorial technologies, it is important to be selective about the number of compounds to be synthesized. Early experience with combinatorial chemistry indicated that chemical diversity alone did not result in a significant increase in the number of generated lead compounds. Emphasis has therefore been increasingly put on the use of computer assisted combinatorial chemical techniques. Computational methods are valuable in the design of virtual libraries of molecular models. Selection strategies based on computed physicochemical properties of the models or of a target compound are introduced to reduce the time and costs of library synthesis and screening. In addition, computational structure-based library focusing methods can be used to perform in silico screening of the activity of compounds against a target receptor by docking the ligands into the receptor model. Three case studies are discussed dealing with the design of targeted combinatorial libraries of inhibitors of HIV-1 protease, P. falciparum plasmepsin and human urokinase as potential antivirial, antimalarial and anticancer drugs. These illustrate library focusing strategies.

  9. Modeling aluminum-silicon chemistries and application to Australian acidic playa lakes as analogues for Mars

    USGS Publications Warehouse

    Marion, G.M.; Crowley, J.K.; Thomson, B.J.; Kargel, J.S.; Bridges, N.T.; Hook, S.J.; Baldridge, A.; Brown, A.J.; Ribeiro da Luz, B.; de Souza, Filho C.R.

    2009-01-01

    Recent Mars missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major relevant findings are the presence in Meridiani Planum sediments of the mineral jarosite (a ferric sulfate salt) and related minerals that require formation from an acid-salt brine and oxidizing environment. Similar mineralogies have been observed in acidic saline lake sediments in Western Australia (WA), and these lakes have been proposed as analogues for acidic sedimentary environments on Mars. The prior version of the equilibrium chemical thermodynamic FREZCHEM model lacked Al and Si chemistries that are needed to appropriately model acidic aqueous geochemistries on Earth and Mars. The objectives of this work were to (1) add Al and Si chemistries to the FREZCHEM model, (2) extend these chemistries to low temperatures (<0 ??C), if possible, and (3) use the reformulated model to investigate parallels in the mineral precipitation behavior of acidic Australian lakes and hypothetical Martian brines. FREZCHEM is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions using the Pitzer approach for the temperature range from <-70 to 25 ??C and the pressure range from 1 to 1000 bars. Aluminum chloride and sulfate mineral parameterizations were based on experimental data. Aluminum hydroxide and silicon mineral parameterizations were based on Gibbs free energy and enthalpy data. New aluminum and silicon parameterizations added 12 new aluminum/silicon minerals to this Na-K-Mg-Ca-Fe(II)-Fe(III)-Al-H-Cl-Br-SO4-NO3-OH-HCO3-CO3-CO2-O2-CH4-Si-H2O system that now contain 95 solid phases. There were similarities, differences, and uncertainties between Australian acidic, saline playa lakes and waters that likely led to the Burns formation salt accumulations on Mars. Both systems are similar in that they are dominated by (1) acidic, saline ground waters and sediments, (2) Ca and/or Mg sulfates, and (3) iron

  10. Modeling aluminum-silicon chemistries and application to Australian acidic playa lakes as analogues for Mars

    NASA Astrophysics Data System (ADS)

    Marion, G. M.; Crowley, J. K.; Thomson, B. J.; Kargel, J. S.; Bridges, N. T.; Hook, S. J.; Baldridge, A.; Brown, A. J.; Ribeiro da Luz, B.; de Souza Filho, C. R.

    2009-06-01

    Recent Mars missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major relevant findings are the presence in Meridiani Planum sediments of the mineral jarosite (a ferric sulfate salt) and related minerals that require formation from an acid-salt brine and oxidizing environment. Similar mineralogies have been observed in acidic saline lake sediments in Western Australia (WA), and these lakes have been proposed as analogues for acidic sedimentary environments on Mars. The prior version of the equilibrium chemical thermodynamic FREZCHEM model lacked Al and Si chemistries that are needed to appropriately model acidic aqueous geochemistries on Earth and Mars. The objectives of this work were to (1) add Al and Si chemistries to the FREZCHEM model, (2) extend these chemistries to low temperatures (<0 °C), if possible, and (3) use the reformulated model to investigate parallels in the mineral precipitation behavior of acidic Australian lakes and hypothetical Martian brines. FREZCHEM is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions using the Pitzer approach for the temperature range from <-70 to 25 °C and the pressure range from 1 to 1000 bars. Aluminum chloride and sulfate mineral parameterizations were based on experimental data. Aluminum hydroxide and silicon mineral parameterizations were based on Gibbs free energy and enthalpy data. New aluminum and silicon parameterizations added 12 new aluminum/silicon minerals to this Na-K-Mg-Ca-Fe(II)-Fe(III)-Al-H-Cl-Br-SO 4-NO 3-OH-HCO 3-CO 3-CO 2-O 2-CH 4-Si-H 2O system that now contain 95 solid phases. There were similarities, differences, and uncertainties between Australian acidic, saline playa lakes and waters that likely led to the Burns formation salt accumulations on Mars. Both systems are similar in that they are dominated by (1) acidic, saline ground waters and sediments, (2) Ca and/or Mg sulfates, and (3) iron

  11. Polarization Properties of Synchrotron Radiation and its Applications.

    NASA Astrophysics Data System (ADS)

    Bjornsson, Claes-Ingvar

    The effects of electron and magnetic field distributions on the polarization properties of optically thin synchrotron radiation are considered. Spectral properties: We show that for all but the most concave upwards spectra, the spectral polarization is given, to an excellent approximation by. (pi)((nu)) = {q('2)((nu)) + u('2)((nu))}(' 1/2)(1 + (alpha))(5/3 + (alpha)). where (alpha) is the local spectral index at any frequency and q((nu)) and u((nu)) involve integrals over the magnetic field geometry. For aligned fields, the square root factor is unity. Information about the magnetic field structure of an optically thin synchrotron source is more readily deduced for source spectra having d(alpha)/dln(nu) > 0. In this case the polarization properties depend mainly on the magnetic field distribution and on the local spectral index (alpha). Two characteristics of the magnetic field distribution are important in determining the spectral polarization properties of a source: the change of alignment with field strength and the form of the distribution's cut-off for high magnetic fields. Generally, when the field alignment increases (decreases) with field strength, the polarization increases (decreases) as a function of local spectral index. We emphasize that for optically thin synchrotron sources, information about the underlying magnetic field distribution can be obtained using accurate measurements of the polarization and spectral index as functions of frequency. Temporal properties: The polarization properties from a source in relativistic motion are considered using a three-dimensional magnetic field distribution. It is assumed that the variation of the polarization is primarily determined by the change in the velocity of the source (i.e., the change of viewing angle (theta) of the magnetic field distribution). The Stokes parameters are evaluated in the restframe of the moving source and then transformed to the observers frame. This gives a convenient parametrization

  12. Applications of penetrating radiation for small animal imaging

    NASA Astrophysics Data System (ADS)

    Hasegawa, Bruce H.; Wu, Max C.; Iwata, Koji; Hwang, Andrew B.; Wong, Kenneth H.; Barber, William C.; Dae, Michael W.; Sakdinawat, Anne E.

    2002-11-01

    Researchers long have relied on research involving small animals to unravel scientific mysteries in the biological sciences, and to develop new diagnostic and therapeutic techniques in the medical and health sciences. Within the past 2 decades, new techniques have been developed to manipulate the genome of the mouse, allowing the development of transgenic and knockout models of mammalian and human disease, development, and physiology. Traditionally, much biological research involving small animals has relied on the use of invasive methods such as organ harvesting, tissue sampling, and autoradiography during which the animal was sacrificed to perform a single measurement. More recently, imaging techniques have been developed that assess anatomy and physiology in the intact animal, in a way that allows the investigator to follow the progression of disease, or to monitor the response to therapeutic interventions. Imaging techniques that use penetrating radiation at millimeter or submillimeter levels to image small animals include x-ray computed tomography (microCT), single-photon emission computed tomography (microSPECT), and imaging positron emission computed tomography (microPET). MicroCT generates cross-sectional slices which reveal the structure of the object with spatial resolution in the range of 50 to 100 microns. MicroSPECT and microPET are radionuclide imaging techniques in which a radiopharmaceutical is injected into the animal that is accumulated to metabolism, blood flow, bone remodeling, tumor growth, or other biological processes. Both microSPECT and microPET offer spatial resolutions in the range of 1-2 millimeters. However, microPET records annihilation photons produced by a positron-emitting radiopharmaceutical using electronic coincidence, and has a sensitivity approximately two orders of magnitude better than microSPECT, while microSPECT is compatible with gamma-ray emitting radiopharmaceuticals that are less expensive and more readily available

  13. Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

    NASA Astrophysics Data System (ADS)

    Mallet, M.; Dulac, F.; Formenti, P.; Nabat, P.; Sciare, J.; Roberts, G.; Pelon, J.; Ancellet, G.; Tanré, D.; Parol, F.; di Sarra, A.; Alados, L.; Arndt, J.; Auriol, F.; Blarel, L.; Bourrianne, T.; Brogniez, G.; Chazette, P.; Chevaillier, S.; Claeys, M.; D'Anna, B.; Denjean, C.; Derimian, Y.; Desboeufs, K.; Di Iorio, T.; Doussin, J.-F.; Durand, P.; Féron, A.; Freney, E.; Gaimoz, C.; Goloub, P.; Gómez-Amo, J. L.; Granados-Muñoz, M. J.; Grand, N.; Hamonou, E.; Jankowiak, I.; Jeannot, M.; Léon, J.-F.; Maillé, M.; Mailler, S.; Meloni, D.; Menut, L.; Momboisse, G.; Nicolas, J.; Podvin, J.; Pont, V.; Rea, G.; Renard, J.-B.; Roblou, L.; Schepanski, K.; Schwarzenboeck, A.; Sellegri, K.; Sicard, M.; Solmon, F.; Somot, S.; Torres, B.; Totems, J.; Triquet, S.; Verdier, N.; Verwaerde, C.; Wenger, J.; Zapf, P.

    2015-07-01

    The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Forcing on the Mediterranean Climate (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental set-up also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modelling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to produce high level of atmospheric pollutants nor

  14. Art in Chemistry: Chemistry in Art. Second Edition

    ERIC Educational Resources Information Center

    Greenberg, Barbara R.; Patterson, Dianne

    2008-01-01

    This textbook integrates chemistry and art with hands-on activities and fascinating demonstrations that enable students to see and understand how the science of chemistry is involved in the creation of art. It investigates such topics as color integrated with electromagnetic radiation, atoms, and ions; paints integrated with classes of matter,…

  15. Biomolecular interactions and tools for their recognition: focus on the quartz crystal microbalance and its diverse surface chemistries and applications.

    PubMed

    Cheng, Cathy I; Chang, Yi-Pin; Chu, Yen-Ho

    2012-03-07

    Interactions between molecules are ubiquitous and occur in our bodies, the food we eat, the air we breathe, and myriad additional contexts. Although numerous tools are available for the recognition of biomolecular interactions, such tools are often limited in their sensitivity, expensive, and difficult to modify for various uses. In contrast, the quartz crystal microbalance (QCM) has sub-nanogram detection capabilities, is label-free, is inexpensive to create, and can be readily modified with a number of diverse surface chemistries to detect and characterize diverse interactions. To maximize the versatility of the QCM, scientists need to know available methods by which QCM surfaces can be modified. Therefore, in addition to summarizing the various tools currently used for biomolecular recognition, explicating the fundamental principles of the QCM as a tool for biomolecular recognition, and comparing the QCM with other acoustic sensors, we systematically review the numerous types of surface chemistries-including hydrophobic bonds, ionic bonds, hydrogen bonds, self-assembled monolayers, plasma-polymerized films, photochemistry, and sensing ionic liquids-used to functionalize QCMs for various purposes. We also review the QCM's diverse applications, which include the detection of gaseous species, detection of carbohydrates, detection of nucleic acids, detection of non-enzymatic proteins, characterization of enzymatic activity, detection of antigens and antibodies, detection of cells, and detection of drugs. Finally, we discuss the ultimate goals of and potential barriers to the development of future QCMs.

  16. Applications Of Monte Carlo Radiation Transport Simulation Techniques For Predicting Single Event Effects In Microelectronics

    SciTech Connect

    Warren, Kevin; Reed, Robert; Weller, Robert; Mendenhall, Marcus; Sierawski, Brian; Schrimpf, Ronald

    2011-06-01

    MRED (Monte Carlo Radiative Energy Deposition) is Vanderbilt University's Geant4 application for simulating radiation events in semiconductors. Geant4 is comprised of the best available computational physics models for the transport of radiation through matter. In addition to basic radiation transport physics contained in the Geant4 core, MRED has the capability to track energy loss in tetrahedral geometric objects, includes a cross section biasing and track weighting technique for variance reduction, and additional features relevant to semiconductor device applications. The crucial element of predicting Single Event Upset (SEU) parameters using radiation transport software is the creation of a dosimetry model that accurately approximates the net collected charge at transistor contacts as a function of deposited energy. The dosimetry technique described here is the multiple sensitive volume (MSV) model. It is shown to be a reasonable approximation of the charge collection process and its parameters can be calibrated to experimental measurements of SEU cross sections. The MSV model, within the framework of MRED, is examined for heavy ion and high-energy proton SEU measurements of a static random access memory.

  17. Evidence for factors modulating radiation-induced G2-delay: potential application as radioprotectors

    NASA Technical Reports Server (NTRS)

    Cheong, N.; Zeng, Z. C.; Wang, Y.; Iliakis, G.

    2001-01-01

    Manipulation of checkpoint response to DNA damage can be developed as a means for protecting astronauts from the adverse effects of unexpected, or background exposures to ionizing radiation. To achieve this goal reagents need to be developed that protect cells from radiation injury by prolonging checkpoint response, thus promoting repair. We present evidence for a low molecular weight substance excreted by cells that dramatically increases the duration of the G2-delay. This compound is termed G2-Arrest Modulating Activity (GAMA). A rat cell line (A1-5) generated by transforming rat embryo fibroblasts with a temperature sensitive form of p53 plus H-ras demonstrates a dramatic increase in radiation resistance after exposure to low LET radiation that is not associated with an increase in the efficiency of rejoining of DNA double strand breaks. Radioresistance in this cell line correlates with a dramatic increase in the duration of the G2 arrest that is modulated by a GAMA produced by actively growing cells. The properties of GAMA suggest that it is a low molecular weight heat-stable peptide. Further characterization of this substance and elucidation of its mechanism of action may allow the development of a biological response modifier with potential applications as a radioprotector. GAMA may be useful for protecting astronauts from radiation injury as preliminary evidence suggests that it is able to modulate the response of cells exposed to heavy ion radiation, similar to that encountered in outer space.

  18. Application of poly(lactic acid) modified by radiation crosslinking

    NASA Astrophysics Data System (ADS)

    Nagasawa, Naotsugu; Kaneda, Ayako; Kanazawa, Shinichi; Yagi, Toshiaki; Mitomo, Hiroshi; Yoshii, Fumio; Tamada, Masao

    2005-07-01

    Poly(L-lactic acid), PLLA was irradiated using electron beam (EB) in the presence of polyfunctional monomers (PFM) as crosslinking agent. Among the PFMs, triallyl isocyanurate (TAIC) at 3% concentration was found to be the most effective for crosslinking of PLLA by irradiation technique. The crosslinked PLLA obtained has heat resistance higher than 200 °C. From this fact, the crosslinked PLLA is applied on heat-shrinkable tube, cup and plate. The shrinkable tube has several advantages such as high heat resistance and transparency. In addition, the unirradiated cup deformed and changed to milky-like transparency but the crosslinked one retained its original shape and transparency after boiling water was poured into the cups. The heat resistance is attributed to the protection of crystallization of crosslinking structure. It is therefore proven that crosslinking technology is beneficial to expanding the application of PLLA.

  19. Laser-plasma SXR/EUV sources: adjustment of radiation parameters for specific applications

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Fiedorowicz, H.; Fok, T.; Jarocki, R.; Kostecki, J.; Szczurek, A.; Szczurek, M.; Wachulak, P.; Wegrzyński, Ł.

    2014-12-01

    In this work soft X-ray (SXR) and extreme ultraviolet (EUV) laser-produced plasma (LPP) sources employing Nd:YAG laser systems of different parameters are presented. First of them is a 10-Hz EUV source, based on a double-stream gaspuff target, irradiated with the 3-ns/0.8J laser pulse. In the second one a 10 ns/10 J/10 Hz laser system is employed and the third one utilizes the laser system with the pulse shorten to approximately 1 ns. Using various gases in the gas puff targets it is possible to obtain intense radiation in different wavelength ranges. This way intense continuous radiation in a wide spectral range as well as quasi-monochromatic radiation was produced. To obtain high EUV or SXR fluence the radiation was focused using three types of grazing incidence collectors and a multilayer Mo/Si collector. First of them is a multfoil gold plated collector consisted of two orthogonal stacks of ellipsoidal mirrors forming a double-focusing device. The second one is the ellipsoidal collector being part of the axisymmetrical ellipsoidal surface. Third of the collectors is composed of two aligned axisymmetrical paraboloidal mirrors optimized for focusing of SXR radiation. The last collector is an off-axis ellipsoidal multilayer Mo/Si mirror allowing for efficient focusing of the radiation in the spectral region centered at λ = 13.5 ± 0.5 nm. In this paper spectra of unaltered EUV or SXR radiation produced in different LPP source configurations together with spectra and fluence values of focused radiation are presented. Specific configurations of the sources were assigned to various applications.

  20. Overview and applications of the Monte Carlo radiation transport kit at LLNL

    SciTech Connect

    Sale, K E

    1999-06-23

    Modern Monte Carlo radiation transport codes can be applied to model most applications of radiation, from optical to TeV photons, from thermal neutrons to heavy ions. Simulations can include any desired level of detail in three-dimensional geometries using the right level of detail in the reaction physics. The technology areas to which we have applied these codes include medical applications, defense, safety and security programs, nuclear safeguards and industrial and research system design and control. The main reason such applications are interesting is that by using these tools substantial savings of time and effort (i.e. money) can be realized. In addition it is possible to separate out and investigate computationally effects which can not be isolated and studied in experiments. In model calculations, just as in real life, one must take care in order to get the correct answer to the right question. Advancing computing technology allows extensions of Monte Carlo applications in two directions. First, as computers become more powerful more problems can be accurately modeled. Second, as computing power becomes cheaper Monte Carlo methods become accessible more widely. An overview of the set of Monte Carlo radiation transport tools in use a LLNL will be presented along with a few examples of applications and future directions.

  1. The application of color display techniques for the analysis of Nimbus infrared radiation data

    NASA Technical Reports Server (NTRS)

    Allison, L. J.; Cherrix, G. T.; Ausfresser, H.

    1972-01-01

    A color enhancement system designed for the Applications Technology Satellite (ATS) spin scan experiment has been adapted for the analysis of Nimbus infrared radiation measurements. For a given scene recorded on magnetic tape by the Nimbus scanning radiometers, a virtually unlimited number of color images can be produced at the ATS Operations Control Center from a color selector paper tape input. Linear image interpolation has produced radiation analyses in which each brightness-color interval has a smooth boundary without any mosaic effects. An annotated latitude-longitude gridding program makes it possible to precisely locate geophysical parameters, which permits accurate interpretation of pertinent meteorological, geological, hydrological, and oceanographic features.

  2. Ozone Radiative Feedback on the Quasi-Biennial Oscillation in the Tropical Stratosphere as Revealed in Chemistry-Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Shibata, K.; Deushi, M.

    2007-12-01

    Simulations on the recent past middle atmosphere were made with a chemistry-climate model (CCM) of Meteorological Research Institute (MRI). Three runs with different transport schemes for chemical species were performed for 25 years from 1980 to 2004. The three transport schemes are formally hybrid semi-Lagrangian type, which is of flux form in the vertical and, at once, of ordinary type in the horizontal, while they use different interpolation and/or approximation in calculating in-cell profiles from cell-average values, resulting in different properties in diffusiveness. The prototype scheme (Cubic3) uses a Lagrangian cubic interpolation of neighboring abundances in the horizontal and also uses it for overhead column abundances in the vertical. To the Cubic3 scheme, two improvements are successively incorporated: one is the piecewise rational-function method (PRM) in the vertical, and the other is a quintic Lagrangian interpolation in the horizontal, resulting in PRM3 (vertically PRM and horizontally cubic) and PRM5 (vertically PRM and horizontally quintic) schemes. The dynamics module of MRI-CCM is a spectral global model of T42 truncation with 68 layers extending from the surface to 0.01 hPa (about 80 km), wherein the vertical spacing is 500m in the stratosphere between 100 hPa and 10 hPa. Hines gravity wave (GW) drag is incorporated with an enhanced GW source in the tropics to spontaneously reproduce the QBO in zonal wind. The chemistry-transport module treats 36 long-lived species including 7 families, and 15 short-lived species with 80 gas phase reactions, 35 photochemical reactions and 9 heterogeneous reactions. MRI-CCM is integrated with observed forcings of SSTs, sea ice, volcanic aerosols, 11-year solar cycle, greenhouse gases, and halogens, the latter two of which are specified at the surface. It is found that PRM3 and PRM5 schemes substantially reduce the systematic positive bias in ozone, particularly in the tropical lower stratosphere and upper

  3. Chemistry 200, 300 Interim Guide.

    ERIC Educational Resources Information Center

    Manitoba Dept. of Education, Winnipeg.

    This guide, developed for the chemistry 200, 300 program in Manitoba, is designed to articulate with previous science courses, provide concepts, processes, and skills which will enable students to continue in chemistry-related areas, and relate chemistry to practical applications in everyday life. It includes a program overview (with program goals…

  4. Development of solvent-free ambient mass spectrometry for green chemistry applications.

    PubMed

    Liu, Pengyuan; Forni, Amanda; Chen, Hao

    2014-04-15

    Green chemistry minimizes chemical process hazards in many ways, including eliminating traditional solvents or using alternative recyclable solvents such as ionic liquids. This concept is now adopted in this study for monitoring solvent-free reactions and analysis of ionic liquids, solids, and catalysts by mass spectrometry (MS), without using any solvent. In our approach, probe electrospray ionization (PESI), an ambient ionization method, was employed for this purpose. Neat viscous room-temperature ionic liquids (RTILs) in trace amounts (e.g., 25 nL) could be directly analyzed without sample carryover effect, thereby enabling high-throughput analysis. With the probe being heated, it can also ionize ionic solid compounds such as organometallic complexes as well as a variety of neat neutral solid chemicals (e.g., amines). More importantly, moisture-sensitive samples (e.g., [bmim][AlCl4]) can be successfully ionized. Furthermore, detection of organometallic catalysts (including air-sensitive [Rh-MeDuPHOS][OTf]) in ionic liquids, a traditionally challenging task due to strong ion suppression effect from ionic liquids, can be enabled using PESI. In addition, PESI can be an ideal approach for monitoring solvent-free reactions. Using PESI-MS, we successfully examined the alkylation of amines by alcohols, the conversion of pyrylium into pyridinium, and the condensation of aldehydes with indoles as well as air- and moisture-sensitive reactions such as the oxidation of ferrocene and the condensation of pyrazoles with borohydride. Interestingly, besides the expected reaction products, the reaction intermediates such as the monopyrazolylborate ion were also observed, providing insightful information for reaction mechanisms. We believe that the presented solvent-free PESI-MS method would impact the green chemistry field.

  5. Nuclear modeling for applications in medical radiation therapy and accelerator-driven technologies

    SciTech Connect

    Chadwick, M.B.

    1995-06-01

    An understanding of the interactions of neutrons and protons below a few hundred MeV with nuclei is important for a number of applications. In this paper, two new applications are discussed: radiation transport calculations of energy deposition in fast neutron and proton cancer radiotherapy to optimize the dose given to a tumor; and intermediate-energy proton accelerators which are currently being designed for a range of applications including the destruction of long-lived radioactive nuclear waste. We describe nuclear theory calculations of direct, preequilibrium, and compound nucleus reaction mechanisms important for the modeling of these systems.

  6. Proteomics Is Analytical Chemistry: Fitness-for-Purpose in the Application of Top-Down and Bottom-Up Analyses.

    PubMed

    Coorssen, Jens R; Yergey, Alfred L

    2015-12-03

    Molecular mechanisms underlying health and disease function at least in part based on the flexibility and fine-tuning afforded by protein isoforms and post-translational modifications. The ability to effectively and consistently resolve these protein species or proteoforms, as well as assess quantitative changes is therefore central to proteomic analyses. Here we discuss the pros and cons of currently available and developing analytical techniques from the perspective of the full spectrum of available tools and their current applications, emphasizing the concept of fitness-for-purpose in experimental design based on consideration of sample size and complexity; this necessarily also addresses analytical reproducibility and its variance. Data quality is considered the primary criterion, and we thus emphasize that the standards of Analytical Chemistry must apply throughout any proteomic analysis.

  7. Proteomics Is Analytical Chemistry: Fitness-for-Purpose in the Application of Top-Down and Bottom-Up Analyses

    PubMed Central

    Coorssen, Jens R.; Yergey, Alfred L.

    2015-01-01

    Molecular mechanisms underlying health and disease function at least in part based on the flexibility and fine-tuning afforded by protein isoforms and post-translational modifications. The ability to effectively and consistently resolve these protein species or proteoforms, as well as assess quantitative changes is therefore central to proteomic analyses. Here we discuss the pros and cons of currently available and developing analytical techniques from the perspective of the full spectrum of available tools and their current applications, emphasizing the concept of fitness-for-purpose in experimental design based on consideration of sample size and complexity; this necessarily also addresses analytical reproducibility and its variance. Data quality is considered the primary criterion, and we thus emphasize that the standards of Analytical Chemistry must apply throughout any proteomic analysis. PMID:28248279

  8. Space Rocks Tell Their Secrets: Space Science Applications of Physics and Chemistry for High School and College Classes. Update.

    NASA Technical Reports Server (NTRS)

    Lindstrom, M. M.; Tobola, K. W.; Allen, J. S.; Stocco, K.; Henry, M.; Allen, J. S.; McReynolds, Julie; Porter, T. Todd; Veile, Jeri

    2005-01-01

    As the scientific community studies Mars remotely for signs of life and uses Martian meteorites as its only available samples, teachers, students, and the general public continue to ask, "How do we know these meteorites are from Mars?" This question sets the stage for a six-lesson instructional package Space Rocks Tell Their Secrets. Expanding on the short answer "It's the chemistry of the rock", students are introduced to the research that reveals the true identities of the rocks. Since few high school or beginning college students have the opportunity to participate in this level of research, a slide presentation introduces them to the labs, samples, and people involved with the research. As they work through the lessons and interpret authentic data, students realize that the research is an application of two basic science concepts taught in the classroom, the electromagnetic spectrum and isotopes. Additional information is included in the original extended abstract.

  9. Space Rocks Tell Their Secrets: Space Science Applications of Physics and Chemistry for High School and College Classes

    NASA Technical Reports Server (NTRS)

    Lindstrom, M. M.; Tobola, K. W.; Stocco, K.; Henry, M.; Allen, J. S.

    2003-01-01

    As the scientific community studies Mars remotely for signs of life and uses Martian meteorites as its only available samples, teachers, students, and the general public continue to ask, "How do we know these meteorites are from Mars?" This question sets the stage for a three-lesson instructional package Space Rocks Tell Their Secrets. Expanding on the short answer "It's the chemistry of the rock", students are introduced to the research that reveals the true identities of the rocks. Since few high school or beginning college students have the opportunity to participate in this level of research, a slide presentation introduces them to the labs, samples, and people involved with the research. As they work through the lessons and interpret real data, students realize that the research is an application of basic science concepts they should know, the electromagnetic spectrum and isotopes. They can understand the results without knowing how to do the research or operate the instruments.

  10. Space Rocks Tell Their Secrets: Space Science Applications of Physics and Chemistry for High School and College Classes: Update

    NASA Technical Reports Server (NTRS)

    Lindstrom, M. M.; Tobola, K. W.; Stocco, K.; Henry, M.; Allen, J. S.; McReynolds, Julie; Porter, T. Todd; Veile, Jeri

    2004-01-01

    As the scientific community studies Mars remotely for signs of life and uses Martian meteorites as its only available samples, teachers, students, and the general public continue to ask, How do we know these meteorites are from Mars? This question sets the stage for a six-lesson instructional package Space Rocks Tell Their Secrets. Expanding on the short answer It s the chemistry of the rock , students are introduced to the research that reveals the true identities of the rocks. Since few high school or beginning college students have the opportunity to participate in this level of research, a slide presentation introduces them to the labs, samples, and people involved with the research. As they work through the lessons and interpret authentic data, students realize that the research is an application of two basic science concepts taught in the classroom, the electromagnetic spectrum and isotopes.

  11. Distance-dependent radiation chemistry: Oxidation versus hydrogenation of CO in electron-irradiated H2O/CO/H2O ices

    SciTech Connect

    Petrik, Nikolay G.; Monckton, Rhiannon J.; Koehler, Sven; Kimmel, Gregory A.

    2014-11-26

    Electron-stimulated oxidation of CO in layered H2O/CO/H2O ices was investigated with infrared reflection-absorption spectroscopy (IRAS) as function of the distance of the CO layer from the water/vacuum interface. The results show that while both oxidation and reduction reactions occur within the irradiated water films, there are distinct regions where either oxidation or reduction reactions are dominant. At depths less than ~ 15 ML, CO oxidation dominates over the sequential hydrogenation of CO to methanol (CH3OH), and CO2 is the major product of CO oxidation, consistent with previous observations. At its highest yield, CO2 accounts for ~45% of all the reacted CO. Another oxidation product is identified as the formate anion (HCO2-). In contrast, for CO buried more than ~ 35 ML below the water/vacuum interface, the CO-to-methanol conversion efficiency is close to 100%. Production of CO2 and formate are not observed for the more deeply buried CO layers, where hydrogenation dominates. Experiments with CO dosed on pre-irradiated ASW samples suggest that OH radicals are primarily responsible for the oxidation reactions. Possible mechanisms of CO oxidation, involving primary and secondary processes of water radiolysis at low temperature, are discussed. The observed distance-dependent radiation chemistry results from the higher mobility of hydrogen atoms that are created by the interaction of the 100 eV electrons with the water films. These hydrogen atoms, which are primarily created at or near the water/vacuum interface, can desorb from or diffuse into the water films, while the less-mobile OH radicals remain in the near-surface zone resulting in preferential oxidation reactions there. The diffusing hydrogen atoms are responsible for the hydrogenation reactions that are dominant for the more deeply buried CO layers.

  12. Implementation and display of Computer Aided Design (CAD) models in Monte Carlo radiation transport and shielding applications

    SciTech Connect

    Burns, T.J.

    1994-03-01

    An Xwindow application capable of importing geometric information directly from two Computer Aided Design (CAD) based formats for use in radiation transport and shielding analyses is being developed at ORNL. The application permits the user to graphically view the geometric models imported from the two formats for verification and debugging. Previous models, specifically formatted for the radiation transport and shielding codes can also be imported. Required extensions to the existing combinatorial geometry analysis routines are discussed. Examples illustrating the various options and features which will be implemented in the application are presented. The use of the application as a visualization tool for the output of the radiation transport codes is also discussed.

  13. Radiation physics, biophysics, and radiation biology. Progress report, December 1, 1993--November 30, 1994

    SciTech Connect

    Hall, E.J.; Zaider, M.

    1994-05-01

    Research at the Center for Radiological Research is a blend of physics, chemistry and biology and epitomizes the multidisciplinary approach towards understanding the mechanisms involved in the health problems resulting from human exposure to ionizing radiations. To an increasing extent, the focus of attention is on biochemistry and the application of the techniques of molecular biology to the problems of radiation biology. Research highlights from the past year are briefly described.

  14. The Effects of Radiation Chemistry on Solvent Extraction: 1. Conditions in Acidic Solution and a Review of TBP Radiolysis

    SciTech Connect

    Bruce J. Mincher; Guiseppe Modolo; Strephen P. Mezyk

    2009-01-01

    Solvent extraction is the most commonly used process scale separation technique for nuclear applications and it benefits from more than 60 years of research and development and proven experience at the industrial scale. Advanced solvent extraction processes for the separation of actinides and fission products from dissolved nuclear fuel are now being investigated worldwide by numerous groups (US, Europe, Russia, Japan etc.) in order to decrease the radiotoxic inventories of nuclear waste. While none of the advanced processes have yet been implemented at the industrial scale their development studies have sometimes reached demonstration tests at the laboratory scale. Most of the partitioning strategies rely on the following four separations: 1. Partitioning of uranium and/or plutonium from spent fuel dissolution liquors. 2. Separation of the heat generating fission products such as strontium and cesium. 3. Coextraction of the trivalent actinides and lanthanides. 4. Separation of the trivalent actinides from the trivalent lanthanides. Tributylphosphate (TBP) in the first separation is the basis of the PUREX, UREX and COEX processes, developed in Europe and the US, whereas monoamides as alternatives for TBP are being developed in Japan and India. For the second separation, many processes were developed worldwide, including the use of crown-ether extractants, like the FPEX process developed in the USA, and the CCD-PEG process jointly developed in the USA and Russia for the partitioning of cesium and strontium. In the third separation, phosphine oxides (CMPOs), malonamides, and diglycolamides are used in the TRUEX, DIAMEX and the ARTIST processes, respectively developed in US, Europe and Japan. Trialkylphosphine oxide(TRPO) developed in China, or UNEX (a mixture of several extractants) jointly developed in Russia and the USA allow all actinides to be co-extracted from acidic radioactive liquid waste. For the final separation, soft donor atom-containing ligands such as

  15. Impact of an external radiation field on handheld XRF measurements for nuclear forensics applications

    SciTech Connect

    Steeb, Jennifer L.; Mertz, Carol J.; Finck, Martha R.; Engelstad, Gary; Carney, Kevin P.; Chamberlain, David B.

    2015-03-28

    X-ray fluorescence (XRF) is an attractive technique for nuclear forensics applications. We evaluated a handheld, portable XRF device by applying an external radiation field (10 mR/h to 17 R/h) using two types of radiography sources: a 60Co radiography camera to observe effects from high-energy gamma emissions and an 192Ir radiography camera to observe effects from several low-energy gamma (0.604, 0.468, and 0.317 MeV) and decay daughter x-ray emissions. External radiation tests proved that radiation, in general, has a significant effect on the dead time or background at dose rates over 1 R/hr for both the 192Ir and 60Co sources.

  16. New apparatus with high radiation energy between 320 to 460 nm: physical description and dermatological applications

    SciTech Connect

    Mutzhas, M.F.; Holzle, E.; Hofmann, C.; Plewig, G.

    1981-01-01

    A new apparatus (UVASUN 5000) is presented with high radiation energy between 320 to 460 nm. The radiator is a specially developed source for high uv-A intensity, housing a quartz bulb with a mixture of argon, mercury and metal-halides. The uv-A energy in the range of 320 to 400 nm is about 84% of the total radiation energy. Effects of very high doses of uv-A on human skin were studied. Following single uv-A applications the minimal tanning dose uv-A (MTD) and the immediate pigment darkening (IPD) dose of uv-A were established. Repeated exposure to this uv-A delivering system yields long lasting dark brown skin pigmentation without any clinical or histological signs of sunburn (uv-B) damage, epidermal hyperplasia or thickening of the stratum corneum. Minimal therapeutic results were seen in the phototherapy of vitiligo and inflammatory acne.

  17. Electromagnetic fields radiated from a lightning return stroke - Application of an exact solution to Maxwell's equations

    NASA Technical Reports Server (NTRS)

    Le Vine, D. M.; Meneghini, R.

    1978-01-01

    A solution is presented for the electromagnetic fields radiated by an arbitrarily oriented current filament over a conducting ground plane in the case where the current propagates along the filament at the speed of light, and this solution is interpreted in terms of radiation from lightning return strokes. The solution is exact in the fullest sense; no mathematical approximations are made, and the governing differential equations and boundary conditions are satisfied. The solution has the additional attribute of being specified in closed form in terms of elementary functions. This solution is discussed from the point of view of deducing lightning current wave forms from measurements of the electromagnetic fields and understanding the effects of channel tortuosity on the radiated fields. In addition, it is compared with two approximate solutions, the traditional moment approximation and the Fraunhofer approximation, and a set of criteria describing their applicability are presented and interpreted.

  18. Modeling Polarized Solar Radiation from Various Scene Types for Satellite Remote-Sensing Applications

    NASA Astrophysics Data System (ADS)

    Sun, W.

    2015-12-01

    To correct the polarization-induced errors in measured reflected solar spectra, the polarization state of the reflected solar light must be known. In this presentation, recent modeling of the polarized solar radiation from the ocean, desert, forest, and clouds is reported. The modeled polarized solar radiation quantities are compared with the PARASOL satellite measurements for various scene types. A novel super-thin cloud optical depth (OD) retrieval method based on polarization measurement is also introduced. This study provides a reliable approach for making the spectral Polarization Distribution Models (PDMs) for satellite inter-calibration applications of NASA's future Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. This study also reports the advance in developing a technique to retrieve super-thin clouds with OD < ~0.3, which are missed by passive satellite sensors like the MODIS. Key words: Reflected solar radiation, polarization, correction of satellite data, retrieval of super-thin clouds.

  19. Chemistry in the Troposphere.

    ERIC Educational Resources Information Center

    Chameides, William L.; Davis, Douglas D.

    1982-01-01

    Topics addressed in this review of chemistry in the troposphere (layer of atmosphere extending from earth's surface to altitude of 10-16km) include: solar radiation/winds; earth/atmosphere interface; kinetic studies of atmospheric reactions; tropospheric free-radical photochemistry; instruments for nitric oxide detection; sampling…

  20. Integrity of the National Resident Matching Program for Radiation Oncology: National Survey of Applicant Experiences

    SciTech Connect

    Holliday, Emma B.; Thomas, Charles R.; Kusano, Aaron S.

    2015-07-01

    Purpose: The aim of this study was to examine the experiences of radiation oncology applicants and to evaluate the prevalence of behaviors that may be in conflict with established ethical standards. Methods and Materials: An anonymous survey was sent to all 2013 applicants to a single domestic radiation oncology residency program through the National Resident Matching Program (NRMP). Questions included demographics, survey of observed behaviors, and opinions regarding the interview and matching process. Descriptive statistics were presented. Characteristics and experiences of respondents who matched were compared with those who did not match. Results: Questionnaires were returned by 87 of 171 applicants for a 51% response rate. Eighty-two questionnaires were complete and included for analysis. Seventy-eight respondents (95.1%) reported being asked at least 1 question in conflict with the NRMP code of conduct. When asked where else they were interviewing, 64% stated that this query made them uncomfortable. Forty-five respondents (54.9%) reported unsolicited post-interview contact by programs, and 31 (37.8%) felt pressured to give assurances. Fifteen respondents (18.3%) reported being told their rank position or that they were “ranked to match” prior to Match day, with 27% of those individuals indicating this information influenced how they ranked programs. Half of respondents felt applicants often made dishonest or misleading assurances, one-third reported that they believed their desired match outcome could be improved by deliberately misleading programs, and more than two-thirds felt their rank position could be improved by having faculty from their home institutions directly contact programs on their behalf. Conclusions: Radiation oncology applicants report a high prevalence of behaviors in conflict with written NRMP policies. Post-interview communication should be discouraged in order to enhance fairness and support the professional development of future

  1. The Materials Chemistry of Atomic Oxygen with Applications to Anisotropic Etching of Submicron Structures in Microelectronics and the Surface Chemistry Engineering of Porous Solids

    SciTech Connect

    Koontz, S.L.; Leger, L.J.; Wu, C.; Cross, J.B.; Jurgensen, C.W. |

    1994-05-01

    Neutral atomic oxygen is the most abundant component of the ionospheric plasma in the low Earth orbit environment (LEO; 200 to 700 kilometers altitude) and can produce significant degradation of some spacecraft materials. In order to produce a more complete understanding of the materials chemistry of atomic oxygen, the chemistry and physics of O-atom interactions with materials were determined in three radically different environments: (1) The Space Shuttle cargo bay in low Earth orbit (the EOIM-3 space flight experiment), (2) a high-velocity neutral atom beam system (HVAB) at Los Alamos National Laboratory (LANL), and (3) a microwave-plasma flowing-discharge system at JSC. The Space Shuttle and the high velocity atom beam systems produce atom-surface collision energies ranging from 0.1 to 7 eV (hyperthermal atoms) under high-vacuum conditions, while the flowing discharge system produces a 0.065 eV surface collision energy at a total pressure of 2 Torr. Data obtained in the three different O-atom environments referred to above show that the rate of O-atom reaction with polymeric materials is strongly dependent on atom kinetic energy, obeying a reactive scattering law which suggests that atom kinetic energy is directly available for overcoming activation barriers in the reaction. General relationships between polymer reactivity with O atoms and polymer composition and molecular structure have been determined. In addition, vacuum ultraviolet photochemical effects have been shown to dominate the reaction of O atoms with fluorocarbon polymers. Finally, studies of the materials chemistry of O atoms have produced results which may be of interest to technologists outside the aerospace industry. Atomic oxygen `spin-off` or `dual use` technologies in the areas of anisotropic etching in microelectronic materials and device processing, as well as surface chemistry engineering of porous solid materials are described.

  2. The Materials Chemistry of Atomic Oxygen with Applications to Anisotropic Etching of Submicron Structures in Microelectronics and the Surface Chemistry Engineering of Porous Solids

    NASA Technical Reports Server (NTRS)

    Koontz, Steve L.; Leger, Lubert J.; Wu, Corina; Cross, Jon B.; Jurgensen, Charles W.

    1994-01-01

    Neutral atomic oxygen is the most abundant component of the ionospheric plasma in the low Earth orbit environment (LEO; 200 to 700 kilometers altitude) and can produce significant degradation of some spacecraft materials. In order to produce a more complete understanding of the materials chemistry of atomic oxygen, the chemistry and physics of O-atom interactions with materials were determined in three radically different environments: (1) The Space Shuttle cargo bay in low Earth orbit (the EOIM-3 space flight experiment), (2) a high-velocity neutral atom beam system (HVAB) at Los Alamos National Laboratory (LANL), and (3) a microwave-plasma flowing-discharge system at JSC. The Space Shuttle and the high velocity atom beam systems produce atom-surface collision energies ranging from 0.1 to 7 eV (hyperthermal atoms) under high-vacuum conditions, while the flowing discharge system produces a 0.065 eV surface collision energy at a total pressure of 2 Torr. Data obtained in the three different O-atom environments referred to above show that the rate of O-atom reaction with polymeric materials is strongly dependent on atom kinetic energy, obeying a reactive scattering law which suggests that atom kinetic energy is directly available for overcoming activation barriers in the reaction. General relationships between polymer reactivity with O atoms and polymer composition and molecular structure have been determined. In addition, vacuum ultraviolet photochemical effects have been shown to dominate the reaction of O atoms with fluorocarbon polymers. Finally, studies of the materials chemistry of O atoms have produced results which may be of interest to technologists outside the aerospace industry. Atomic oxygen 'spin-off' or 'dual use' technologies in the areas of anisotropic etching in microelectronic materials and device processing, as well as surface chemistry engineering of porous solid materials are described.

  3. Recent applications of the Cu(I)-catalysed Huisgen azide-alkyne 1,3-dipolar cycloaddition reaction in carbohydrate chemistry.

    PubMed

    Dedola, Simone; Nepogodiev, Sergey A; Field, Robert A

    2007-04-07

    This article surveys recent applications of Cu(I)-catalysed 1,3-dipolar cycloaddition of azides and alkynes in carbohydrate chemistry, highlighting developments in the preparation of simple glycoside and oligosaccharide mimetics, glyco-macrocycles, glycopeptides, glyco-clusters and carbohydrate arrays.

  4. Development and Application of a Two-Tier Multiple Choice Diagnostic Instrument To Assess High School Students' Understanding of Inorganic Chemistry Qualitative Analysis.

    ERIC Educational Resources Information Center

    Tan, Kim Chwee Daniel; Goh, Ngoh Khang; Chia, Lian Sai; Treagust, David F.

    2002-01-01

    Describes the development and application of a two-tier multiple choice diagnostic instrument to assess high school students' understanding of inorganic chemistry qualitative analysis. Shows that the Grade 10 students had difficulty understanding the reactions involved in the identification of cations and anions, for example, double decomposition…

  5. Modeling aqueous ferrous iron chemistry at low temperatures with application to Mars

    USGS Publications Warehouse

    Marion, G.M.; Catling, D.C.; Kargel, J.S.

    2003-01-01

    Major uncertainties exist with respect to the aqueous geochemical evolution of the Martian surface. Considering the prevailing cryogenic climates and the abundance of salts and iron minerals on Mars, any attempt at comprehensive modeling of Martian aqueous chemistry should include iron chemistry and be valid at low temperatures and high solution concentrations. The objectives of this paper were to (1) estimate ferrous iron Pitzer-equation parameters and iron mineral solubility products at low temperatures (from < 0 ??C to 25 ??C), (2) incorporate these parameters and solubility products into the FREZCHEM model, and (3) use the model to simulate the surficial aqueous geochemical evolution of Mars. Ferrous iron Pitzer-equation parameters were derived in this work or taken from the literature. Six new iron minerals [FeCl2??4H2O, FeCl2??6H2O, FeSO4??H2O, FeSO4??7H2O, FeCO3, and Fe(OH)3] were added to the FREZCHEM model bringing the total solid phases to 56. Agreement between model predictions and experimental data are fair to excellent for the ferrous systems: Fe-Cl, Fe-SO4, Fe-HCO3, H-Fe-Cl, and H-Fe-SO4. We quantified a conceptual model for the aqueous geochemical evolution of the Martian surface. The five stages of the conceptual model are: (1) carbonic acid weathering of primary ferromagnesian minerals to form an initial magnesium-iron-bicarbonate-rich solution; (2) evaporation and precipitation of carbonates, including siderite (FeCO3), with evolution of the brine to a concentrated NaCl solution; (3) ferrous/ferric iron oxidation; (4) either evaporation or freezing of the brine to dryness; and (5) surface acidification. What began as a dilute Mg-Fe-HCO3 dominated leachate representing ferromagnesian weathering evolved into an Earth-like seawater composition dominated by NaCl, and finally into a hypersaline Mg-Na-SO4-Cl brine. Weathering appears to have taken place initially under conditions that allowed solution of ferrous iron [low O2(g)], but later caused

  6. Simultaneous assessment of phase chemistry, phase abundance and bulk chemistry with statistical electron probe micro-analyses: Application to cement clinkers

    SciTech Connect

    Wilson, William; Krakowiak, Konrad J.; Ulm, Franz-Josef

    2014-01-15

    According to recent developments in cement clinker engineering, the optimization of chemical substitutions in the main clinker phases offers a promising approach to improve both reactivity and grindability of clinkers. Thus, monitoring the chemistry of the phases may become part of the quality control at the cement plants, along with the usual measurements of the abundance of the mineralogical phases (quantitative X-ray diffraction) and the bulk chemistry (X-ray fluorescence). This paper presents a new method to assess these three complementary quantities with a single experiment. The method is based on electron microprobe spot analyses, performed over a grid located on a representative surface of the sample and interpreted with advanced statistical tools. This paper describes the method and the experimental program performed on industrial clinkers to establish the accuracy in comparison to conventional methods. -- Highlights: •A new method of clinker characterization •Combination of electron probe technique with cluster analysis •Simultaneous assessment of phase abundance, composition and bulk chemistry •Experimental validation performed on industrial clinkers.

  7. Radiation stability and modification of gelatin for biological and medical applications

    NASA Astrophysics Data System (ADS)

    Haema, Kamonwon; Oyama, Tomoko Gowa; Kimura, Atsushi; Taguchi, Mitsumasa

    2014-10-01

    Gelatin is used in various biological and medical fields, including drug delivery systems and tissue engineering. In the context of these applications, radiation sterilization of gelatin was evaluated in terms of radiation stability. The molecular weight of gelatin powder irradiated by electron beams (EB) was analyzed using gel permeation chromatography (GPC). We found that irradiation decomposed the gelatin and that the weight-averaged molar mass (Mw) decreased by approximately 7-10% with sterilization doses in the range of 5-25 kGy. Also, we found that the hydrolysis rate in body and cell culture environments (37 °C water) was affected by irradiation. Although gelatin powder underwent chain scission when irradiated, crosslinking was predominantly induced when the gelatin was irradiated in water solution. Radiation-crosslinked (RX) gelatin hydrogel was fabricated without using any crosslinkers. In this case, fabrication and radiation sterilization were performed simultaneously. Using gel fraction and GPC analysis of the eluted sol, it was determined that the RX-gelatin hydrogel was stable for 7 days in water at 37 °C. These results provide important data for evaluating the feasibility of biological and medical applications of gelatin and RX-gelatin hydrogel.

  8. Carbon nano-onions (multi-layer fullerenes): chemistry and applications

    PubMed Central

    Bartelmess, Juergen

    2014-01-01

    Summary This review focuses on the development of multi-layer fullerenes, known as carbon nano-onions (CNOs). First, it briefly summarizes the most important synthetic pathways for their preparation and their properties and it gives the reader an update over new developments in the recent years. This is followed by a discussion of the published synthetic procedures for CNO functionalization, which are of major importance when elucidating future applications and addressing drawbacks for possible applications, such as poor solubility in common solvents. Finally, it gives an overview over the fields of application, in which CNO materials were successfully implemented. PMID:25383308

  9. The 'SAR Matrix' method and its extensions for applications in medicinal chemistry and chemogenomics.

    PubMed

    Gupta-Ostermann, Disha; Bajorath, Jürgen

    2014-01-01

    We describe the 'Structure-Activity Relationship (SAR) Matrix' (SARM) methodology that is based upon a special two-step application of the matched molecular pair (MMP) formalism. The SARM method has originally been designed for the extraction, organization, and visualization of compound series and associated SAR information from compound data sets. It has been further developed and adapted for other applications including compound design, activity prediction, library extension, and the navigation of multi-target activity spaces. The SARM approach and its extensions are presented here in context to introduce different types of applications and provide an example for the evolution of a computational methodology in pharmaceutical research.

  10. Development and applications of radiative transfer models for unpolarized and polarized light

    NASA Astrophysics Data System (ADS)

    Lin, Zhenyi

    Radiative transfer models play an important role in satellite remote sensing of the atmosphere and the underlying surface including the ocean as well as for studying the energy budget of the Earth. Proper analysis of radiance and polarized radiation measurements rely on accurate and reliable radiative transfer models. Among the various numerical approaches developed to solve the radiative transfer equation, the ones based on the discrete-ordinate method, DISORT, as well as its polarized (vector) version VDISORT, have led to quite successful radiative transfer models that have been widely applied as forward models for the simulation of radiative transfer in coupled atmosphere-ocean media. In this dissertation, we first discuss new developments of DISORT and VDISORT, and review the relevant radiative transfer theory behind the upgraded algorithms. We then proceed to discuss applications of radiative transfer simulations that make use of each model. The upgrade of DISORT discussed in this thesis includes in the following improvements: (1) enhanced computational efficiency, accuracy and stability; (2) implementation new lower boundary conditions to simulate reflection from realistic (rough) land and ocean surfaces; (3) a revised treatment of the single-scattering correction. Numerical results are provided to demonstrate and quantify the improvements in accuracy and efficiency by comparing previous and upgraded versions of the numerical codes. One challenging problem in remote sensing applications is the simulation of ocean glint reflectance, which is reflected solar radiation from a wind-roughened ocean surface. For geometries close to specular reflection the glint signal is sufficiently strong that it may saturate the sensor, and even when saturation does not occur correct simulation of this signal is a difficult problem. In an exciting new application, we show for the first time that glint radiances in the near infrared spectral range simulated with the upgraded

  11. Applications of the New Family of Coherent Multidimensional Spectroscopies for Analytical Chemistry.

    PubMed

    Wright, John C

    2017-03-27

    A new family of vibrational and electronic spectroscopies has emerged, comprising the coherent analogs of traditional analytical methods. These methods are also analogs of coherent multidimensional nuclear magnetic resonance (NMR) spectroscopy. This new family is based on creating the same quantum mechanical superposition states called multiple quantum coherences (MQCs). NMR MQCs are mixtures of nuclear spin states that retain their quantum mechanical phase information for milliseconds. The MQCs in this new family are mixtures of vibrational and electronic states that retain their phases for picoseconds or shorter times. Ultrafast, high-intensity coherent beams rapidly excite multiple states. The excited MQCs then emit bright beams while they retain their phases. Time-domain methods measure the frequencies of the MQCs by resolving their phase oscillations, whereas frequency-domain methods measure the resonance enhancements of the output beam while scanning the excitation frequencies. The resulting spectra provide multidimensional spectral signatures that increase the spectroscopic selectivity required for analyzing complex samples. Expected final online publication date for the Annual Review of Analytical Chemistry Volume 10 is June 12, 2017. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  12. Chemokine Receptor CCR5 Antagonist Maraviroc: Medicinal Chemistry and Clinical Applications

    PubMed Central

    Xu, Guoyan G.; Guo, Jia; Wu, Yuntao

    2015-01-01

    The human immunodeficiency virus (HIV) causes acquired immumodeficiency syndrome (AIDS), one of the worst global pandemic. The virus infects human CD4 T cells and macrophages, and causes CD4 depletion. HIV enters target cells through the binding of the viral envelope glycoprotein to CD4 and the chemokine coreceptor, CXCR4 or CCR5. In particular, the CCR5-utilizing viruses predominate in the blood during the disease course. CCR5 is expressed on the surface of various immune cells including macrophages, monocytes, microglia, dendric cells, and active memory CD4 T cells. In the human population, the CCR5 genomic mutation, CCR5Δ32, is associated with relative resistance to HIV. These findings paved the way for the discovery and development of CCR5 inhibitors to block HIV transmission and replication. Maraviroc, discovered as a CCR5 antagonist, is the only CCR5 inhibitor that has been approved by both US FDA and the European Medicines Agency (EMA) for treating HIV/AIDS patients. In this review, we summarize the medicinal chemistry and clinical studies of Maraviroc. PMID:25159165

  13. Computing gas solubility in reservoir waters for environmental chemistry applications: the role of satellite observations

    NASA Astrophysics Data System (ADS)

    Rosa, R.; Lima, I.; Ramos, F.; Bambace, L.; Assireu, A.; Stech, J.; Novo, E.; Lorenzeti, L.

    Atmospheric greenhouse gases concentration has increased during the past centuries basically due to biogenic and pyrogenic anthopogenic emissions Recent investigations have shown that gas emission methane as an important example from tropical hydroelectric reservoirs may comprise a considerable fraction of the total anthropogenic bulk In order to evaluate the concentration of gases of potential importance in environmental chemistry the solubility of such gases have been collected and converted into a uniform format using the Henry s law which states that the solubility of a gas in a liquid is directly proportional to its partial pressure However the Henry s law can be derived as a function of temperature density molar mixing ratio in the aqueous phase and molar mass of water In this paper we show that due to the complex temperature variation and water composition measured in brazilian tropical reservoirs as Serra da Mesa and Manso expressive secular variation on the traditional solubility constants concentration of a species in the aqueous phase by the partial pressure of that species in the gas phase can change in a rate of approximately 30 in 6 decades This estimation comes from a computational analysis of temperature variation measured during 6 months in Serra da Mesa and Manso reservoirs taking into account a simulated density and molar mass variation of the aqueous composition in these environments As an important global change issue from this preliminary analysis we discuss its role in the current estimations on the concentration emission rates

  14. Chemokine receptor CCR5 antagonist maraviroc: medicinal chemistry and clinical applications.

    PubMed

    Xu, Guoyan G; Guo, Jia; Wu, Yuntao

    2014-01-01

    The human immunodeficiency virus (HIV) causes acquired immumodeficiency syndrome (AIDS), one of the worst global pandemic. The virus infects human CD4 T cells and macrophages, and causes CD4 depletion. HIV enters target cells through the binding of the viral envelope glycoprotein to CD4 and the chemokine coreceptor, CXCR4 or CCR5. In particular, the CCR5-utilizing viruses predominate in the blood during the disease course. CCR5 is expressed on the surface of various immune cells including macrophages, monocytes, microglia, dendric cells, and active memory CD4 T cells. In the human population, the CCR5 genomic mutation, CCR5Δ32, is associated with relative resistance to HIV. These findings paved the way for the discovery and development of CCR5 inhibitors to block HIV transmission and replication. Maraviroc, discovered as a CCR5 antagonist, is the only CCR5 inhibitor that has been approved by both US FDA and the European Medicines Agency (EMA) for treating HIV/AIDS patients. In this review, we summarize the medicinal chemistry and clinical studies of Maraviroc.

  15. Quantitative Clinical Chemistry Proteomics (qCCP) using mass spectrometry: general characteristics and application.

    PubMed

    Lehmann, Sylvain; Hoofnagle, Andrew; Hochstrasser, Denis; Brede, Cato; Glueckmann, Matthias; Cocho, José A; Ceglarek, Uta; Lenz, Christof; Vialaret, Jérôme; Scherl, Alexander; Hirtz, Christophe

    2013-05-01

    Proteomics studies typically aim to exhaustively detect peptides/proteins in a given biological sample. Over the past decade, the number of publications using proteomics methodologies has exploded. This was made possible due to the availability of high-quality genomic data and many technological advances in the fields of microfluidics and mass spectrometry. Proteomics in biomedical research was initially used in 'functional' studies for the identification of proteins involved in pathophysiological processes, complexes and networks. Improved sensitivity of instrumentation facilitated the analysis of even more complex sample types, including human biological fluids. It is at that point the field of clinical proteomics was born, and its fundamental aim was the discovery and (ideally) validation of biomarkers for the diagnosis, prognosis, or therapeutic monitoring of disease. Eventually, it was recognized that the technologies used in clinical proteomics studies [particularly liquid chromatography-tandem mass spectrometry (LC-MS/MS)] could represent an alternative to classical immunochemical assays. Prior to deploying MS in the measurement of peptides/proteins in the clinical laboratory, it seems likely that traditional proteomics workflows and data management systems will need to adapt to the clinical environment and meet in vitro diagnostic (IVD) regulatory constraints. This defines a new field, as reviewed in this article, that we have termed quantitative Clinical Chemistry Proteomics (qCCP).

  16. Responsive hydrogels produced via organic sol-gel chemistry for cell culture applications.

    PubMed

    Patil, Smruti; Chaudhury, Pulkit; Clarizia, Lisa; McDonald, Melisenda; Reynaud, Emmanuelle; Gaines, Peter; Schmidt, Daniel F

    2012-08-01

    In this study, we report the synthesis of novel environmentally responsive polyurea hydrogel networks prepared via organic sol-gel chemistry and demonstrate that the networks can stabilize pH while releasing glucose both in simple aqueous media and in mammalian cell culture settings. Hydrogel formulations have been developed based on the combination of an aliphatic triisocyanate with pH-insensitive amine functional polyether and pH-sensitive poly(ethyleneimine) segments in a minimally toxic solvent suitable for the sol-gel reaction. The polyether component of the polyurea network is sufficiently hydrophilic to give rise to some level of swelling independent of environmental pH, while the poly(ethyleneimine) component contains tertiary amine groups providing pH sensitivity to the network in the form of enhanced swelling and release under acidic conditions. The reaction of these materials to form a network is rapid and requires no catalyst. The resultant material exhibits the desired pH-responsive swelling behavior and demonstrates its ability to simultaneously neutralize lactic acid and release glucose in both cell-free culture media and mammalian cell culture, with no detectable evidence of cytotoxicity or changes in cell behavior, in the case of either SA-13 human hybridomas or mouse embryonic stem cells. Furthermore, pH is observed to have a clear effect on the rate at which glucose is released from the hydrogel network. Such characteristics promise to maintain a favorable cell culture environment in the absence of human intervention.

  17. Hydrogen Water Chemistry Technology in Boiling Water Reactors

    SciTech Connect

    Lin, Chien C

    2000-04-15

    Modification of coolant chemistry by feedwater hydrogen addition in boiling water reactors (BWRs), generally called hydrogen water chemistry (HWC), is a viable option to mitigate the intergranular stress corrosion cracking problems for operating BWRs. Some fundamentals in HWC technologies as known today are reviewed. Several full-scale HWC test results are analyzed, and the roles that hydrogen plays in HWC technology are identified and quantitatively evaluated. Some deficiencies in water radiolysis modeling for BWR applications under HWC conditions and the impact of {sup 16}N radiation field increase in the main steam line are also discussed.

  18. Implementation and initial application of new chemistry-aerosol options in WRF/Chem for simulating secondary organic aerosols and aerosol indirect effects for regional air quality

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Zhang, Yang; Yahya, Khairunnisa; Wu, Shiang-Yuh; Grell, Georg

    2015-08-01

    Atmospheric aerosols play important roles in affecting regional meteorology and air quality through aerosol direct and indirect effects. Two new chemistry-aerosol options have been developed in WRF/Chem v3.4.1 by incorporating the 2005 Carbon Bond (CB05) mechanism and coupling it with the existing aerosol module MADE with SORGAM and VBS modules for simulating secondary organic aerosol (SOA), aqueous-phase chemistry in both large scale and convective clouds, and aerosol feedback processes (hereafter CB05-MADE/SORGAM and CB05-MADE/VBS). As part of the Air Quality Model Evaluation International Initiative (AQMEII) Phase II model intercomparison that focuses on online-coupled meteorology and chemistry models, WRF/Chem with the two new options is applied to an area over North America for July 2006 episode. The simulations with both options can reproduce reasonably well most of the observed meteorological variables, chemical concentrations, and aerosol/cloud properties. Compared to CB05-MADE/SORGAM, CB05-MADE/VBS greatly improves the model performance for organic carbon (OC) and PM2.5, reducing NMBs from -81.2% to -13.1% and from -26.1% to -15.6%, respectively. Sensitivity simulations show that the aerosol indirect effects (including aqueous-phase chemistry) can reduce the net surface solar radiation by up to 53 W m-2 with a domainwide mean of 12 W m-2 through affecting cloud formation and radiation scattering and reflection by increasing cloud cover, which in turn reduce the surface temperature, NO2 photolytic rate, and planetary boundary layer height by up to 0.3 °C, 3.7 min-1, and 64 m, respectively. The changes of those meteorological variables further impact the air quality through the complex chemistry-aerosol-cloud-radiation interactions by reducing O3 mixing ratios by up to 5.0 ppb. The results of this work demonstrate the importance of aerosol indirect effects on the regional climate and air quality. For comparison, the impacts of aerosol direct effects on both

  19. An assessment of inservice training on the applications in biology/chemistry curriculum from the Center of Occupational Research and Development

    NASA Astrophysics Data System (ADS)

    Jobe, Robert Dale

    Scope and method of study. The scope of the study consisted of respondents to a survey sent to all the participants of the inservice workshops for the Applied Biology/Chemistry curriculum from CORD. One hundred and six surveys were sent to teachers trained for Applied Biology/Chemistry classes for high school credit as a laboratory science requirement. Sixty-two people returned the questionnaire who were present or past teachers of Applied Biology/Chemistry classes for high school credit. The study assessed the participants' expectations and satisfaction with inservice training provided for certification in Oklahoma over the past five years. A common set of objectives that participants rated for importance to philosophy and strategies needed to successfully teach Applications in Biology/Chemistry using the curriculum written by the Center for Occupational Research and Development was evaluated for significance. Findings and conclusions. The analysis of the data revealed that the respondents' expectations and satisfaction were both above average for the workshop they attended. Therefore, it was concluded that the first seventeen objectives of this study should be the mainstay of any workshop used to train future teachers of Applications of Biology/Chemistry for high school credit. Eleven of the first seventeen questions (objectives) were found to be statistically significant at the alpha =.05 level. Therefore it was concluded that an increased emphasis on instruction in the guideline (objectives) areas that were statistically significant should be provided in future workshops. The respondents' answers to the survey questions provided insight on the time line configuration and structure of future workshops for teachers of Application in Biology/Chemistry for high school credit. Therefore it was concluded that workshops should be ten days in length, 6-8 hours a day of instruction, with follow-up sessions offered, college credit given and a stipend awarded. The days

  20. Design and calculation of low infrared transmittance and low emissivity coatings for heat radiative applications

    NASA Astrophysics Data System (ADS)

    Wang, Guang-Hai; Zhang, Yue; Zhang, Da-Hai; Fan, Jin-Peng

    2012-02-01

    The infrared transmittance and emissivity of heat-insulating coatings pigmented with various structural particles were studied using Kubelka-Munk theory and Mie theory. The primary design purpose was to obtain the low transmittance and low emissivity coatings to reduce the heat transfer by thermal radiation for high-temperature applications. In the case of silica coating layers constituted with various structural titania particles (solid, hollow, and core-shell spherical), the dependence of transmittance and emissivity of the coating layer on the particle structure and the layer thickness was investigated and optimized. The results indicate that the coating pigmented with core-shell titania particles exhibits a lower infrared transmittance and a lower emissivity value than that with other structural particles and is suitable to radiative heat-insulating applications.