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Sample records for proton microprobe study

  1. Proton microprobe studies of the mineralization process in selected organic matrices

    NASA Astrophysics Data System (ADS)

    Rokita, E.; Cichocki, T.; Divoux, S.; Gonsior, B.; Höfert, M.; Jarczyk, L.; Strzalkowski, A.; Sych, M.

    1990-04-01

    The application of the proton-induced X-ray emission method in combination with a proton microprobe (micro-PIXE) to studies of the mineralization process in selected organic matrices is presented. The flat-bone mineralization of the skull of 17-19 days pregnancy mouse embryos is described in detail. The section thickness as well as concentrations of P, S, Cl, K, Ca, Zn and Br were determined using the raster- or line-scan irradiation mode. On the basis of Ca and P contents the amount of inorganic phase was determined for each sample under investigation, while the Ca/P ratio was used for the identification of the chemical compounds within inorganic material. In the embryonal bones we observed almost stoichiometric hydroxyapatite; however, in the intramembranaceous ossification of the young (17 day) animals, octacalcium phosphate was identified. At the given age of the embryo the amount of minerals is much higher in the femur bone than in flat bone. The micro-PIXE method furthermore turned out to be sensitive enough to study the mineralization accompanying malignant tumors. We have also observed the involvement of some trace elements in the development of the mineralization process. The last two observations are unattainable by histological staining.

  2. Accumulation of calcium and loss of potassium in the hippocampus following transient cerebral ischemia: a proton microprobe study

    SciTech Connect

    Martins, E.; Inamura, K.; Themner, K.; Malmqvist, K.G.; Siesjoe, B.K.

    1988-08-01

    This study explored (a) whether postischemic accumulation of calcium in hippocampal neurons precedes or occurs pari passu with light microscopical signs of delayed neuronal necrosis, and (b) whether calcium initially accumulates in dendritic domains, presumed to have a high density of agonist-operated calcium channels. Transient ischemia of 10-min duration was induced in rats, and the animals were studied after 1, 2, 3, and 4 days of recovery. We measured total calcium and potassium contents in the stratum oriens, pyramidale, radiatum, and moleculare of the CA1 and CA3 sectors, using particle induced x-ray emission (PIXE) in the proton microprobe mode. The results showed significant accumulation of calcium and loss of potassium after 3 and 4 days of recovery in the CA1 sector, which developed neuronal necrosis, but not in the CA3 sector, which showed only occasional damage. In a few animals, calcium accumulation (and loss of potassium) was observed with no or only mild visible damage, but in the majority of animals the accumulation of calcium correlated to signs of neuronal necrosis. Since calcium accumulation was similar in all strata examined, the results failed to reveal preferential accumulation in dendritic or somal regions. Based on our results and those of Dux et al., we emphasize the possibility that delayed neuronal death is, at least in part, caused by increased calcium cycling of plasma membranes and gradual calcium overload of mitochondria.

  3. Elemental mapping of biological samples using a scanning proton microprobe

    NASA Astrophysics Data System (ADS)

    Watt, F.; Grime, G. W.

    1988-03-01

    Elemental mapping using a scanning proton microprobe (SPM) can be a powerful technique for probing trace elements in biology, allowing complex interfaces to be studied in detail, identifying contamination and artefacts present in the specimen, and in certain circumstances obtaining indirect chemical information. Examples used to illustrate the advantages of the technique include the elemental mapping of growing pollen tubes, honey bee brain section, a mouse macrophage cell, human liver section exhibiting primary biliary cirrhosis, and the attack by a mildew fungus on a pea leaf.

  4. Submicron elemental mapping with the oxford scanning proton microprobe

    NASA Astrophysics Data System (ADS)

    Grime, G. W.; Watt, F.; Chapman, J. R.

    1987-03-01

    Following recent modifications to the Oxford scanning proton microprobe (SPM) a beam spot diameter of 0.5 μm has been achieved at a beam current of 20-30 pA of 4 MeV protons. This has been confirmed by scanning both a copper test grid and microcrystals of barium sulphate. The potential of using high spatial resolutions in microbiology has been explored by scanning a single mouse cell.

  5. The Oxford scanning proton microprobe: A medical diagnostic application

    NASA Astrophysics Data System (ADS)

    Watt, F.; Grime, G. W.; Takacs, J.; Vaux, D. J. T.

    1984-04-01

    Primary biliary cirrhosis (PBC) is a disease characterised by progressive destruction of small intrahepatic bile ducts, cholestasis, and high levels of copper within the liver. The Oxford 1 μm scanning proton microprobe (SPM) has been used to construct elemental maps of a 7 μm section of diseased liver at several different magnifications. The results of these investigations have shown that the copper is distributed in small deposits ( < 5 μm) at specific locations in the liver. Further there appears to be a 1:1 atomic correlation between copper and sulphur, indicating the presence of an inorganic salt or a protein with approximately equal numbers of copper and sulphur atoms.

  6. [Investigation of Carbonaceous Airborne Particles by Scanning Proton Microprobe].

    PubMed

    Bao, Liang-man; Liu, Jiang-feng; Lei, Qian-tao; Li, Xiao-lin; Zhang, Gui-lin; Li, Yan

    2016-01-15

    Carbonaceous particles are an important component of the atmospheric aerosol particles and important for global climate change, air quality and human health. The PM₁₀ single particles from two environmental monitor locations and seven pollution emission sources were analyzed using scanning proton microprobe (SPM) techniques. The concentration of carbon in individual particles was quantitatively determined by proton non-Rutherford elastic backscattering spectrometry (EBS). The results of this investigation showed that carbonaceous particles were dominant in the pollution sources of coal and oil combustions, diesel busexhaust and automobile exhaust, while inorganic particles were dominant in the sources of steel industry, cement dust and soil dust. Carbonaceous matter was enriched in particles from the city center, while mineral matter was the main component of airborne particles in the industrial area. Elemental mapping of single aerosol particles yielded important information on the chemical reactions of aerosol particles. The micro-PIXE (particle induced X-ray emission) maps of S, Ca and Fe of individual carbonaceous particles showed that sulfuration reaction occurred between SO₂and mineral particles, which increased the sulfur content of particles. PMID:27078933

  7. Application of the Karlsruhe proton microprobe to medical samples

    NASA Astrophysics Data System (ADS)

    Heck, D.; Rokita, E.

    1984-04-01

    The Karlsruhe nuclear microprobe was used in the investigation of healthy and malign tissue of animals and men. Target preparation tests showed that cryofixation of the tissue before cutting with a microtome and succeeding lyophilization of the slices gave reliable results. The slices were mounted on backing foils of Formvar the thickness of which varied between 30 and 50 {μg}/{cm 2}. For irradiation we tested various patterns generated by the 3 MeV proton beam by sweeping in one or two dimensions. Most of the data were collected in line-scan mode, where 256 equidistant irradiation dots of 3 × 10 μm 2 formed a line of 750 μm length at beam currents of 250 pA. The target thickness was determined simultaneously by proton elastic scattering in all cases. Radial concentration profiles of degenerated human arteries (atherosclerosis) showed a remarkable increase of Ca, partly correlated with local maxima of the Zn content, when compared with non-degenerated capillaries. Microtome cuts across a Morris Hepatoma 7777 cancer grown in a rat leg were investigated to correlate the concentration shifts of some trace elements in malign tissue with single cells.

  8. Trace elemental analysis of bituminuos coals using the Heidelberg proton microprobe

    USGS Publications Warehouse

    Chen, J.R.; Kneis, H.; Martin, B.; Nobiling, R.; Traxel, K.; Chao, E.C.T.; Minkin, J.A.

    1981-01-01

    Trace elements in coal can occur as components of either the organic constituents (macerals) or the inorganic constituents (minerals). Studies of the concentrations and distribution of the trace elements are vital to understanding the geochemical millieu in which the coal was formed and in evaluating the attempts to recover rare but technologically valuable metals. In addition, information on the trace element concentrations is important in predicting the environmental impact of burning particular coals, as many countries move toward greater utilization of coal reserves for energy production. Traditionally, the optical and the electron microscopes and more recently the electron microprobe have been used in studying the components of coal. The proton-induced X-ray emission (PIXE) microprobe offers a new complementary approach with an order of magnitude or more better minimum detection limit. We present the first measurements with a PIXE microprobe of the trace element concentrations of bituminous coal samples. Elemental analyses of the coal macerals-vitrinite, exinite, and inertinite-are discussed for three coal samples from the Eastern U.S.A., three samples from the Western U.S.A., and one sample from the Peoples Republic of China. ?? 1981.

  9. PROTON MICROPROBE ANALYSIS OF TRACE-ELEMENT VARIATIONS IN VITRINITES IN THE SAME AND DIFFERENT COAL BEDS.

    USGS Publications Warehouse

    Minkin, J.A.; Chao, E.C.T.; Blank, Herma; Dulong, F.T.

    1987-01-01

    The PIXE (proton-induced X-ray emission) microprobe can be used for nondestructive, in-situ analyses of areas as small as those analyzed by the electron microprobe, and has a sensitivity of detection as much as two orders of magnitude better than the electron microprobe. Preliminary studies demonstrated that PIXE provides a capability for quantitative determination of elemental concentrations in individual coal maceral grains with a detection limit of 1-10 ppm for most elements analyzed. Encouraged by the earlier results, we carried out the analyses reported below to examine trace element variations laterally (over a km range) as well as vertically (cm to m) in the I and J coal beds in the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale in central Utah, and to compare the data with the data from two samples of eastern coals of Pennsylvanian age.

  10. First direct-write lithography results on the Guelph high resolution proton microprobe

    NASA Astrophysics Data System (ADS)

    Wang, L. P.; de Kerckhove, D.

    2011-10-01

    The recently completed high-resolution proton microprobe at the University of Guelph is Canada's first one-micron nuclear microprobe, which represents the country's state-of-the-art technology for various nuclear microprobe applications, e.g. direct-write microlithography. Its probe-forming system is comprised of a triplet Oxford Micro beams magnetic quadrupole lenses, along with high-precision objective slits. High energy protons coming off a 3 MV particle accelerator can achieve a nominal resolution of one micro and a beam current of several hundred of picoamperes when arriving at the target. This proton probe is ideal for the use of direct-write lithography with the incorporation of a magnetic scanning system and motorized sample stage. Preliminary lithography results have been obtained using spin-coated PMMA photoresist as specimen. The beam spot size, beam range and straggling inside the substrate and the exposure conditions are investigated by using scanning electron microscopy. This facility is the first in Canada to perform focused direct-write ion beam lithography, which is ideal for modification and machining of polymer and semiconductor materials for biological, microfluidic and ultimate lab-on-chip applications.

  11. PIXE profiling, imaging and analysis using the NAC proton microprobe: Unraveling mantle eclogites

    NASA Astrophysics Data System (ADS)

    van Achterbergh, Esmé; Ryan, Chris G.; Gurney, John J.; Le Roex, Anton P.

    1995-09-01

    The National Accelerator Centre (NAC) proton microprobe has been carefully calibrated by the analysis of pure element, primary steel and geological standards. The results obtained are generally accurate to within 5%. For routine analyses (6-8 min), detection limits in the X-ray energy region 7-20 keV, range from 1.5 to 5 ppm. Previous workers have suggested the use of a (H 2) + beam for semi-quantitative analysis and imaging as higher beam brightness is obtainable with this beam at NAC. However, insufficient suppression of electrons introduces significant analytical error. Only a 3 MeV H + beam has been used for the quantitative analysis reported in this work. A rare suite of xenoliths, consisting of interlayered kyanite-bearing and kyanite-free eclogite, from the Roberts Victor kimberlite, Northern Cape, South Africa, was prepared as polished thin-sections and analyzed by the proton microprobe as a pilot study of trace element signatures in its component minerals (garnet, clinopyroxene and kyanite). The analysis of these eclogites identified significant chemical differences between the minerals of the kyanite-bearing and kyanite-free eclogite. Two clear groupings were distinguished well outside statistical error for Mn, Zn and Zr in garnet, and Mn, Ga, Sr and Ba in the clinopyroxene. Furthermore, clear chemical gradients in the elements Mn, Fe, Zn, Y and Zr were identified in single garnets at the contact between the two eclogite types. True elemental imaging revealed a heterogeneous distribution of the elements Sr and Ba in the clinopyroxene; the presence of Ba is interpreted to indicate the introduction of foreign material. A compositional dependence of the partitioning of Zn between garnet and clinopyroxene was also identified. The data do not contradict a previous hypothesis that the kyanite eclogite zones are the metamorphic products of a plagioclase-rich crystal protolith, but they do challenge the proposal that the layering is a primary feature of the rock

  12. Development of a bio-PIXE setup at the Debrecen scanning proton microprobe

    NASA Astrophysics Data System (ADS)

    Kertész, Zs.; Szikszai, Z.; Uzonyi, I.; Simon, A.; Kiss, Á. Z.

    2005-04-01

    On the growing need of an accurate, quantitative method for the analysis of thin biological tissues down to the cell level, a measurement setup and data evaluating system has been developed at the Debrecen scanning proton microprobe facility, using its unique capability of the PIXE-PIXE technique. Quantitative elemental concentrations and true elemental maps from C to U can be produced in the case of thin (10-50 μm), inhomogeneous samples of organic matrix with a 2 μm lateral resolution. The method is based on the combined application of on-axis STIM and PIXE-PIXE ion beam analytical techniques. STIM spectra and maps are used to determine the morphology and the area density of the samples. PIXE spectra and maps of an ultra thin windowed and a conventional Be-windowed Si(Li) X-ray detectors are used to quantify concentrations and distributions of elements in the C to Fe (light and medium) and S to U (medium and heavy) atomic number regions, separately. For cross-checking the validation of the obtained data in a few cases RBS technique was used simultaneously. The application of the new bio-PIXE method is shown through an example, the study of the penetration and clearance of ultra-fine particles containing heavy metals (TiO2) of physical bodycare cosmetics in different layers of skin within the frame of the NANODERM EU5 project.

  13. Scanning proton microprobe analysis applied to wood and bark samples

    NASA Astrophysics Data System (ADS)

    Lövestam, N. E. G.; Johansson, E.-M.; Johansson, S. A. E.; Pallon, J.

    1990-04-01

    In this study the feasibility of applying scanning micro-PIXE to analysis of wood and bark samples is demonstrated. Elemental mapping of the analysed sections show the patterns of Cl, K, Ca, Mn, Fe, Cu and Zn. Some of these patterns can be related to the annual tree ring structure. It is observed that the variation of elements having an environmental character can be rather large within a single tree ring, thus illuminating possible difficulties when using tree ring sections as a pollution monitor. The variations in elemental concentrations when crossing from bark to wood are also shown to be smooth for some elements but rather abrupt for others.

  14. Microprobe and oxygen fugacity study of armalcolite

    NASA Technical Reports Server (NTRS)

    Friel, J. J.

    1976-01-01

    The stability of synthetic armalcolite was determined as a function of oxygen fugacity with particular regard to the oxidation state of iron and titanium. The equilibrium pseudobrookite (armalcolite) composition was measured at 1200 C under various conditions of oxidation typical of the lunar environment. These data, when compared with published descriptions of mare basalts, provide information about the conditions of crystallization of armalcolite-bearing lunar rocks. Some information about the crystal chemistry of armalcolite was obtained from X-ray diffraction and electron microprobe analyses of synthetic armalcolite and Zr-armalcolite. Further data were gathered from a comparison of the Mossbauer spectra of a phase pure stoichiometric armalcolite and one containing appreciable amounts of trivalent titanium.

  15. The new external beam facility of the Oxford scanning proton microprobe

    NASA Astrophysics Data System (ADS)

    Grime, G. W.; Abraham, M. H.; Marsh, M. A.

    2001-07-01

    This paper describes the development of a high spatial resolution external beam facility on one of the beamlines of the Oxford scanning proton microprobe tandem accelerator. Using a magnetic quadrupole doublet to focus the beam through the Kapton exit window a beam diameter of <50 μm full width at half maximum (fwhm) can be achieved on a sample located at 4 mm from the exit window. The facility is equipped with two Si-Li X-ray detectors for proton-induced X-ray emission (PIXE) analysis of light and trace elements respectively, a surface barrier detector for Rutherford backscattering spectrometry (RBS) analysis and a HP-Ge detector for γ-ray detection. The mechanical and beam-optical design of the system is described.

  16. High resolution imaging and elemental analysis of PAGE electrophoretograms by scanning proton microprobe

    NASA Astrophysics Data System (ADS)

    Szőkefalvi-Nagy, Z.; Kocsonya, A.; Kovács, I.; Hopff, D.; Lüthje, S.; Niecke, M.

    2009-06-01

    Metal content of metalloproteins can be detected and even quantified by the PIXE-PAGE method. In this technique the proteins are separated by thin layer electrophoresis (by polyacrylamide gel electrophoresis (PAGE) in most cases) and the properly dried gel sections are analyzed by PIXE using "band-shaped" proton milli-beam. This PIXE-PAGE method was adapted for our scanning proton microprobe. The microPIXE-PAGE version provides two-dimensional elemental mapping of the protein bands. In addition, the fast continuous scanning reduces the risk of the thermal deterioration of the sample and the X-ray contribution from dust-impurities can be filtered out in the data evaluation process.

  17. Mapping the Earth's mantle in 4D using the proton microprobe

    NASA Astrophysics Data System (ADS)

    Griffin, W. L.; Ryan, C. G.; Win, T. T.

    1995-09-01

    The CSIRO proton microprobe is used to study the trace element chemistry of garnet and chromite grains recovered from kimberlites and other volcanic rocks, both to develop new diamond exploration methods and to further understanding of the makeup and evolution of the earth's upper mantle. Analysis of the partitioning of trace and major elements between garnet and chromite and their coexisting phases in mantle rocks has led to the development of two single-mineral thermometers and a barometer. Trace Ni in Cr-pyrope garnet is used to determine the equilibration temperature ( TNi) of each garnet grain. This is the temperature of the garnet in its source rock before it was entrained in the erupting magma. Similarly, trace Zn in chromite yields an estimate ( TZn) of its equilibration temperature. To relate these temperature to depth in the lithosphere a measure of pressure ( PCr) has been developed that estimates pressure directly from Cr-pyrope garnet composition and TNi. This breakthrough enables the information on rock composition and metasomatic processes held in the trace and major element chemistry of each garnet to be located in P and T and thus placed in its stratigraphic context. Y, Ga and Cr provide information on mantle depletion by partial melting. Zr, Y and Ti provide clues to metasomatic processes such as infiltration of asthenospheric melts. Together the result is both an improved diamond exploration tool and a method of mapping the 3D structure, lithology and metasomatic processes in the lithosphere. With the added knowledge of the date of each intrusion, these methods permit the construction of 4D maps of the lithosphere, charting variation in mantle composition both laterally, with depth and through time.

  18. Volatility in the lunar crust: Trace element analyses of lunar minerals by PIXE proton microprobe

    NASA Technical Reports Server (NTRS)

    Norman, M. D.; Griffin, W. L.; Ryan, C. G.

    1993-01-01

    In situ determination of mineral compositions using microbeam techniques can characterize magma compositions through mineral-melt partitioning, and be used to investigate fine-grained or rare phases which cannot be extracted for analysis. Abundances of Fe, Mn, Sr, Ga, Zr, Y, Nb, Zn, Cu, Ni, Se, and Sb were determined for various mineral phases in a small number of lunar highlands rocks using the PIXE proton microprobe. Sr/Ga ratios of plagioclase and Mn/Zn ratios of mafic silicates show that the ferroan anorthosites and Mg-suite cumulates are depleted in volatile lithophile elements to about the same degree compared with chondrites and the Earth. This links the entire lunar crust to common processes or source compositions. In contrast, secondary sulfides in Descartes breccia clasts are enriched in chalcophile elements such as Cu, Zn, Ni, Se, and Sb, and represent a potential resource in the lunar highlands.

  19. Deposition of corrosion products from dowels on human dental root surfaces measured with proton microprobe technique

    NASA Astrophysics Data System (ADS)

    Brune, D.; Brunell, G.; Lindh, U.

    1982-06-01

    Distribution of copper, mercury and zinc on human teeth root surfaces adjacent to dowels of gold alloy or brass as well as dowels of brass in conjunction with an amalgam crown has been measured with a proton microprobe using PIXE techniques. Upper limits of the contents of gold and silver on the root surfaces were established. Pronounced concentration profiles of copper and zinc were observed on the root surfaces of teeth prepared with dowels of brass. The dowel of gold alloy revealed only zinc deposition. The major part of copper on the root surfaces is assumed to arise from corrosion of the dowels, and has been transported to the surface by diffusion through the dential tubuli. Zinc in the volume analysed is a constituent of dentin tissue as well as a corrosion product of the brass dowel. Part of the zinc level could also be ascribed to erosion of the zinc phosphate cement matrix. The volumes analysed were (25×25×25)μm 3. The levels of copper, mercury and zinc on the tooth root surfaces attained values up to about 200, 20 and 600 ppm, respectively.

  20. Nuclear Microprobe using Elastic Recoil Detection (ERD) for Hydrogen Profiling in High Temperature Protonic Conductors

    NASA Technical Reports Server (NTRS)

    Berger, Pascal; Sayir, Ali; Berger, Marie-Helene

    2004-01-01

    The interaction between hydrogen and various high temperature protonic conductors (HTPC) has not been clearly understood due to poor densification and unreacted secondary phases. the melt-processing technique is used in producing fully dense simple SrCe(0.9)Y (0.10) O(3-delta) and complex Sr3Ca(1+x)Nb(2+x)O(9-delta) perovskites that can not be achieved by solid-state sintering. the possibilities of ion beam analysis have been investigated to quantify hydrogen distribution in HTPC perovskites subjected to water heat treatment. Nuclear microprobe technique is based on the interactions of a focused ion beam of MeV light ions (H-1, H-2, He-3, He-4,.) with the sample to be analyzed to determine local elemental concentrations at the cubic micrometer scale, the elastic recoil detection analysis technique (ERDA) has been carried out using He-4(+) microbeams and detecting the resulting recoil protons. Mappings of longitudinal sections of water treated SrCeO3 and Sr(Ca(1/3)Nb(2/3))O3 perovskites have been achieved, the water treatment strongly alters the surface of simple SrCe(0.9)Y(0.10)O(3-delta) perovskite. From Rutherford Back Scattering measurements (RBS), both Ce depletion and surface re-deposition is evidenced. the ERDA investigations on water treated Sr3Ca(1+x)Nb(2+x)O(9-delta) perovskite did not exhibit any spatial difference for the hydrogen incorporation from the surface to the centre. the amount of hydrogen incorporation for Sr3Ca(1+x)Nb(2+x)O(9-delta) was low and required further development of two less conventional techniques, ERDA in forward geometry and forward elastic diffusion H-1(p,p) H-1 with coincidence detection.

  1. A High Resolution Microprobe Study of EETA79001 Lithology C

    NASA Technical Reports Server (NTRS)

    Schrader, Christian M.; Cohen, B. A.; Donovan, J. J.; Vicenzi, E. P.

    2010-01-01

    Antarctic meteorite EETA79001 has received substantial attention for possibly containing a component of Martian soil in its impact glass (Lithology C) [1]. The composition of Martian soil can illuminate near-surface processes such as impact gardening [2] and hydrothermal and volcanic activity [3,4]. Impact melts in meteorites represent our most direct samples of Martian regolith. We present the initial findings from a high-resolution electron microprobe study of Lithology C from Martian meteorite EETA79001. As this study develops we aim to extract details of a potential soil composition and to examine Martian surface processes using elemental ratios and correlations.

  2. Correlated petrographic, electron microprobe, and ion microprobe studies of selected primitive and processed phase assemblages in meteorites

    NASA Technical Reports Server (NTRS)

    Albee, Arden L.

    1993-01-01

    During the past three years we have received support to continue our research in elucidating the formation and alteration histories of selected meteoritic materials by a combination of petrographic, trace element, and isotopic analyses employing optical and scanning electron microscopes and electron and ion microprobes. The awarded research funds enabled the P.I. to attend the annual LPSC, the co-I to devote approximately 15 percent of his time to the research proposed in the grant, and partial support for a visiting summer post-doctoral fellow to conduct electron microprobe analyses of meteoritic samples in our laboratory. The research funds, along with support from the NASA Education Initiative awarded to P.I. G. Wasserburg, enabled the co-I to continue a mentoring program with inner-city minority youth. The support enabled us to achieve significant results in the five projects that we proposed (in addition to the Education Initiative), namely: studies of the accretional and post-accretional alteration and thermal histories in CV meteorites, characterization of periclase-bearing Fremdlinge in CV meteorites, characterization of Ni-Pt-Ge-Te-rich Fremdlinge in CV meteorites in an attempt to determine the constraints they place on the petrogenetic and thermal histories of their host CAI's, correlated electron and ion microprobe studies of silicate and phosphate inclusions in the Colomera meteorite in an attempt to determine the petrogenesis of the IE iron meteorites, and development of improved instrumental and correction procedures for improved accuracy of analysis of meteoritic materials with the electron microprobe. This grant supported, in part or whole, 18 publications so far by our research team, with at least three more papers anticipated. The list of these publications is included. The details of the research results are briefly summarized.

  3. Raman microprobe spectroscopic studies of solid DNA-CTMA films

    NASA Astrophysics Data System (ADS)

    Yaney, Perry P.; Ahmad, Faizan; Grote, James G.

    2008-08-01

    Extensive studies have been carried out on developing the new biopolymer, deoxyribonucleic acid (DNA) derived from salmon, that has been complexed with a surfactant to make it water insoluble for application to bioelectronic and biophotonic devices. One of the key issues associated with the properties and behavior of solid films of this material is the extreme size of the >8 MDa molecular weight of the virgin, as-received material. Reduction of this molecular weight by factors of up to 40 is achieved by high power sonication. To support the various measurements that have been made to confirm that the sonicated material is still double strand DNA and to look for other effects of sonication, Raman studies were carried out to compare the spectra over a wide range of molecular weights and to develop baseline data that can be used in intercolation studies where various dopants are added to change the electrical, mechanical or optical properties. Raman microprobe spectra from solid, dry thin films of DNA with molecular weights ranging from 200 kDa to >8 MDa complexed with cetyltrimethyl-ammonium chloride (CTMA) are reported and compared to the as-received spectrum and to published DNA spectra in aqueous solutions. In addition, microscopy and measurements on macro-molecular structures of DNA-CTMA are reported.

  4. Proton microprobe and X-ray fluorescence investigations of nickel distribution in serpentine flora from South Africa

    NASA Astrophysics Data System (ADS)

    Mesjasz-Przybyłowicz, J.; Balkwill, K.; Przybyłowicz, W. J.; Annegarn, H. J.

    1994-05-01

    Certain plant species growing on serpentinite soils are hyperaccumulative of Ni. The ability to tolerate high Ni levels may have useful environmental and economic implications. However, the processes of Ni accumulation and tolerance are not well understood. The proton microprobe of the Schonland Research Centre was used in the PIXE mode to map the lateral and cross-sectional distribution of Ni and other elements in the tissue of species from the family Asteraceae, growing on serpentine outcrops in the Barberton district, south-eastern Transvaal. Elemental maps showed that the highest Ni enrichment was in the epidermis. Energy dispersive XRF fluorescence analysis was used for qualitative rapid scanning to select suitable metal-rich plants and for quantitative bulk analyses.

  5. Fiber optic microprobes with rare-earth-based phosphor tips for proton beam characterization

    NASA Astrophysics Data System (ADS)

    Darafsheh, Arash; Kassaee, Alireza; Taleei, Reza; Dolney, Derek; Finlay, Jarod C.

    2016-03-01

    We investigated the feasibility of using fiber optics probes with rare-earth-based phosphor tips for proton beam radiation dosimetry. We designed and fabricated a fiber probe with submillimeter resolution based on TbF3 phosphors and evaluated its performance for measurement of proton beams including profiles and range. The fiber optic probe, embedded in tissue-mimicking plastics, was irradiated with a clinical proton beam and the luminescence spectroscopy was performed by a CCD-coupled spectrograph to analyze the emission spectra of the fiber tip. By using a linear fitting algorithm we extracted the contribution of the ionoluminescence signal to obtain the percentage depth dose in phantoms and compared that with measurements performed with a standard ion chamber. We observed a quenching effect in the spread out Bragg peak region, manifested as an under-responding of the signal due to the high linear energy transfer of the beam. However, the beam profiles measurements were not affected by the quenching effect indicating that the fiber probes can be used for high-resolution measurements of proton beams profile.

  6. Nuclear microprobe analysis of solar proton implantation profiles in lunar rock surfaces

    NASA Technical Reports Server (NTRS)

    Stauber, M. C.; Padawer, G. M.; D'Agostino, M. D.; Kamykowski, E.; Brandt, W.; Young, D. A.

    1973-01-01

    Discussion of the results of hydrogen (proton) depth profile concentration analyses conducted on selected Apollo 16 rocks. A modeling of solar particle implantation profiles in lunar rocks is shown to trace the evolvement of these profiles under the combined influence of diffusion of atomic particles implanted in the rock, and rock surface erosion. It is also demonstrated that such diffusion may have a significant effect on the shape of the implantation profiles in certain rock materials.

  7. Experimental study on the mechanical interaction between silicon neural microprobes and rat dura mater during insertion.

    PubMed

    Fekete, Z; Németh, A; Márton, G; Ulbert, I; Pongrácz, A

    2015-02-01

    In vivo insertion experiments are essential to optimize novel neural implants. Our work focuses on the interaction between intact dura mater of rats and as-fabricated single-shaft silicon microprobes realized by deep reactive ion etching. Implantation parameters like penetration force and dimpling through intact dura mater were studied as a function of insertion speed, microprobe cross-section, tip angle and animal age. To reduce tissue resistance, we proposed a unique tip sharpening technique, which was also evaluated in in vivo insertion tests. By doubling the insertion speed (between 1.2 and 10.5 mm/min), an increase of 10-35% in penetration forces was measured. When decreasing the cross-section of the microprobes, penetration forces and dimpling was reduced by as much as 30-50% at constant insertion speeds. Force was noticed to gradually decrease by decreasing tip angles. Measured penetration forces through dura mater were reduced even down to 11±3 mN compared to unsharpened (49±13 mN) probes by utilizing our unique tip sharpening technique, which is very close to exerted penetration force in the case of retracted dura (5±1.5 mN). Our findings imply that age remarkably alters the elasticity of intact dura mater. The decreasing stiffness of dura mater results in a significant rise in penetration force and decrease in dimpling. Our work is the first in vivo comparative study on microelectrode penetration through intact and retracted dura mater. PMID:25631267

  8. Study of microstructure and silicon segregation in cast iron using color etching and electron microprobe analysis

    SciTech Connect

    Vazehrad, S.; Diószegi, A.

    2015-06-15

    An investigation on silicon segregation of lamellar, compacted and nodular graphite iron was carried out by applying a selective, immersion color etching and a modified electron microprobe to study the microstructure. The color etched micrographs of the investigated cast irons by revealing the austenite phase have provided data about the chronology and mechanism of microstructure formation. Moreover, electron microprobe has provided two dimensional segregation maps of silicon. A good agreement was found between the segregation profile of silicon in the color etched microstructure and the silicon maps achieved by electron microprobe analysis. However, quantitative silicon investigation was found to be more accurate than color etching results to study the size of the eutectic colonies. - Highlights: • Sensitivity of a color etchant to silicon segregation is quantitatively demonstrated. • Si segregation measurement by EMPA approved the results achieved by color etching. • Color etched micrographs provided data about solidification mechanism in cast irons. • Austenite grain boundaries were identified by measuring the local Si concentration.

  9. An Electron Microprobe Study of Synthetic Aluminosilicate Garnets

    NASA Astrophysics Data System (ADS)

    Fournelle, J.; Geiger, C. A.

    2010-12-01

    The aluminosilicate garnets represent an important mineral group. Common end-members are given by E3Al2Si3O12, where E=Fe2+ (almandine), Mn2+ (spessartine), Mg (pyrope), and Ca (grossular). End-members have been synthesized, but their exact compositions and stoichiometries are generally unknown. Synthetic aluminosilicate garnet can possibly contain minor Fe3+, Mn3+, F- and OH- and possibly vacancies. Slight atomic disorder over the 3 different cation sites may also occur. Natural crystals are considerably more complex. Electron probe microanalysis (EPMA) provides a method to determine garnet chemistry and stoichiometry. However, accurate determinations are not always a simple matter and uncertainties exist. We have started a study on well-characterized synthetic aluminosilicate garnets in order to i) determine more exactly their compositions and stoichiometries and ii) better understand possible complications in EPMA. Synthetic almandine, spessartine, pyrope, and grossular samples were synthesized under varying conditions both hydrothermally and dry and with different starting materials. A closed thermodynamic system was present and the bulk starting material composition represented the exact stoichiometric end-member garnet that was desired. IR, Raman and Mössbauer spectroscopy in some cases and X-ray diffraction were used to characterize the samples. Synthetic pyrope has been investigated with a SX51 with simple oxide/silicate standards (Fo90 olivine for Mg, wollastonite for Si, and both Al2O3 and kyanite for Al). Previously observed problems were reproduced: low stoichiometry for Al and high for Si and Mg. Fournelle (2007, AGU Fall Mtg) noted chemical peak shifts for Al and Mg Ka in garnets; this effect was eliminated here by proper peaking. Earlier suggestions for issues with mass absorption coefficients were not seen, and Probe for EPMA software demonstrated there was not much difference between the most recent FFAST values vs. the older Heinrich values

  10. Progresses in proton radioactivity studies

    NASA Astrophysics Data System (ADS)

    Ferreira, L. S.; Maglione, E.

    2016-07-01

    In the present talk, we will discuss recent progresses in the theoretical study of proton radioactivity and their impact on the present understanding of nuclear structure at the extremes of proton stability.

  11. Hydrogen incorporation into high temperature protonic conductors: Nuclear microprobe microanalysis by means of 1H(p, p) 1H scattering

    NASA Astrophysics Data System (ADS)

    Berger, P.; Gallien, J.-P.; Khodja, H.; Daudin, L.; Berger, M.-H.; Sayir, A.

    2006-08-01

    Protonic conductivity of some solid state materials at an intermediate temperature range (400-600 °C), referred as high temperature protonic conductor (HTPC), suggests their application as electrolytes in electrochemical cells, batteries, sensors, etc. Among them, some perovskites can be protonic and electronic conductors. Several obstacles remain to achieve the full potential of these ceramic membranes, among them the lack of measurement techniques and of an unambiguous model for conductivity. A precise understanding of the transport mechanisms requires local profiling of hydrogen concentrations within the microstructure of the ceramic. We have used the nuclear microprobe of the Laboratoire Pierre SÜE to investigate quantitatively the spatial distribution of hydrogen after water heat treatment of textured perovskites, SrCe0.9Y0.1O3-δ and Sr3Ca1+xNb2-xO9-δ, x = 0.18, synthesized according to a melt-process developed at NASA GRC. A not very common method has been developed for hydrogen measurements in thin samples, 1H(p, p)1H elastic recoil coincidence spectrometry (ERCS). Early experiments have evidenced hydrogen concentration enhancement within grain boundaries.

  12. The use of the RBI nuclear microprobe in conservation process studies of a church portal

    NASA Astrophysics Data System (ADS)

    Pastuović, Ž.; Fazinić, S.; Jakšić, M.; Krstić, D.; Mudronja, D.

    2005-04-01

    The southern portal of the St. Marko church in Zagreb, Croatia, is currently under the process of conservation. The conservation treatments on calcareous sandstone consist of (i) removal of harmful sulfates (gypsum) from the surface of the material by saturated solution of ammonium carbonate; and (ii) treatment of the material surface with a 10% solution of barium hydroxide in order to convert the remaining dissolvable sulfates into non-dissolvable compounds and to strengthen the material surface. The nuclear microprobe has been used to measure the level of gypsum induced damage, and quality of conservation. More specifically, the surface quantity and depth concentration profiles of sulfur have been determined in several samples taken from the portal before and after the treatment with the solution of ammonium carbonate. To test the quality of treatment by the barium hydroxide solution, the depth concentration of barium in the samples has been determined after the treatment. Both sulfur and barium concentration levels have been determined by scanning the focused proton beam over the samples, detecting PIXE spectra and creating elemental distribution maps. Beside portal samples, the efficiency of the barium hydroxide treatment was tested on sandstone samples from nearby stone pit assumed to be the origin of material used for portal construction.

  13. Study of proton radioactivities

    SciTech Connect

    Davids, C.N.; Back, B.B.; Henderson, D.J.

    1995-08-01

    About a dozen nuclei are currently known to accomplish their radioactive decay by emitting a proton. These nuclei are situated far from the valley of stability, and mark the very limits of existence for proton-rich nuclei: the proton drip line. A new 39-ms proton radioactivity was observed following the bombardment of a {sup 96}Ru target by a beam of 420-MeV {sup 78}Kr. Using the double-sided Si strip detector implantation system at the FMA, a proton group having an energy of 1.05 MeV was observed, correlated with the implantation of ions having mass 167. The subsequent daughter decay was identified as {sup 166}Os by its characteristic alpha decay, and therefore the proton emitter is assigned to the {sup 167}Ir nucleus. Further analysis showed that a second weak proton group from the same nucleus is present, indicating an isomeric state. Two other proton emitters were discovered recently at the FMA: {sup 171}Au and {sup 185}Bi, which is the heaviest known proton radioactivity. The measured decay energies and half-lives will enable the angular momentum of the emitted protons to be determined, thus providing spectroscopic information on nuclei that are beyond the proton drip line. In addition, the decay energy yields the mass of the nucleus, providing a sensitive test of mass models in this extremely proton-rich region of the chart of the nuclides. Additional searches for proton emitters will be conducted in the future, in order to extend our knowledge of the location of the proton drip line.

  14. Study of ancient Islamic gilded pieces combining PIXE-RBS on external microprobe with sem images

    NASA Astrophysics Data System (ADS)

    Ynsa, M. D.; Chamón, J.; Gutiérrez, P. C.; Gomez-Morilla, I.; Enguita, O.; Pardo, A. I.; Arroyo, M.; Barrio, J.; Ferretti, M.; Climent-Font, A.

    2008-07-01

    Numerous metallic objects with very aesthetic and technological qualities have been recovered by archaeological excavations. Adequate processes of restoration and conservation treatments require the accurate determination of the elemental composition and distribution within the objects, as well as the identification of the nature and distribution of the corrosion products. Ideally the identification method should cause no alteration in the sample. In this work, different archaeological pieces with a gilded look have been characterized using simultaneously PIXE and RBS at the CMAM external microprobe in order to study the gilding metalworking done in the Iberian Peninsula during the Middle Ages. The gold layer thickness and its elemental concentrations of Ag, Au and Hg were determined by both techniques and compared with the scanning electron microscopy images obtained for some fragments of pieces.

  15. Microprobe PIXE study of Ni-Ge interactions in lateral diffusion couples

    NASA Astrophysics Data System (ADS)

    Chilukusha, D.; Pineda-Vargas, C. A.; Nemutudi, R.; Habanyama, A.; Comrie, C. M.

    2015-11-01

    Rutherford backscattering spectrometry on the nuclear microprobe (μRBS) is often used in studies of lateral diffusion couples. RBS requires that the positions of the interacting species on the periodic table are not too close in terms of atomic number and therefore do not produce excessive RBS peak overlap. In order to satisfactorily characterize systems that have atomic numbers which are close, it is necessary to find techniques which can complement μRBS. The aim of this study was to determine the extent to which particle induced X-ray emission (PIXE) could be applied in the lateral diffusion couple study of a system with relatively close atomic numbers. This was with a view that it may eventually be adopted to study systems where the atomic numbers are too close for RBS analysis. The system studied here was the Ni-Ge binary system. Since RBS is an established technique for studying lateral diffusion couples, we used it as a standard for comparison. The PIXE results showed a maximum error of 12% with reference to the RBS standard. In order to achieve the most effective use of PIXE in lateral diffusion couple studies we recommend the use of the technique in such a way as to obtain depth information and the use of relatively thick sample layers.

  16. A combination of size-resolved particle samplers and XRF microprobe technique for single particle study

    NASA Astrophysics Data System (ADS)

    Ma, Chang-Jin; Kim, Ki-Hyun

    It is important to understand the properties of individual airborne particulates that are determined by the processes of various physicochemical reactions occurring in their generation, transformation, and transport. This study describes the application of the X-ray fluorescence (XRF) microprobe technique to the analysis of size-resolved individual particles as well as the results of an experimental study on the comparison of three different particle collection instruments for single particle analysis: a two-stage filter pack, a low pressure Andersen impactor (LPAI), and a micro-orifice uniform deposit impactor (MOUDI). Though LPAI and MOUDI are relatively suitable for multisize-segregated particles sampling compared with the two-stage filter pack sampler, they can easily form particle clusters and finally these particle clusters impede single particle analysis. Even though more particle mass can be collected without overloading on the substrate using MOUDI, by stage rotating, particles are still deposited and form clusters on the concentric circles. When particles are forming a spot (or other shapes of particle cluster), single particle analysis using the XRF micro-beam technique is restricted to individual particles deposited at the edge of the spot. Thus, the sampling duration time depending on the sampler stage should be adjusted for single particle study.

  17. Studies of solid DNA-CTMA films using Raman microprobe spectroscopy

    NASA Astrophysics Data System (ADS)

    Ahmad, Faizan; Yaney, Perry

    2008-10-01

    Extensive research has been conducted on the development of deoxyribonucleic acid (DNA) - based electrical and electro-optical devices using purified DNA originally derived from salmon waste. However, the molecular weight of the virgin, as received DNA is greater than 8000 kDa, whereas the electrical and electro-optical properties are optimum at lower molecular weights. High power sonication is used to reduce the molecular weight of the obtained DNA to levels as low as 200 kDa, in which higher power and longer exposure produces lower mean molecular weight. The DNA is then complexed with cetyltrimethl-ammonium chloride (CTMA) to make it water insoluble. To support the various measurements that have been made to confirm that the sonicated material is still double strand DNA and to look for other effects of sonication, Raman studies were carried out to compare the spectra over a wide range of molecular weights and to develop baseline data that can be used in correlation studies when various dopants are added to change the electrical, mechanical or optical properties. Raman microprobe spectra from solid, dry thin films of DNA with molecular weights ranging from 200 kDa to >8 MDa complexed with cetyltrimethyl-ammonium chloride (CTMA) are presented and correlated with the as-received spectrum, the CTMA spectrum and with published DNA spectra in aqueous solutions.

  18. Nuclear microprobe study of TiO 2-penetration in the epidermis of human skin xenografts

    NASA Astrophysics Data System (ADS)

    Kertész, Zs.; Szikszai, Z.; Gontier, E.; Moretto, P.; Surlève-Bazeille, J.-E.; Kiss, B.; Juhász, I.; Hunyadi, J.; Kiss, Á. Z.

    2005-04-01

    Titanium-dioxide is a widely used physical photoprotective component of various cosmetic products. However, very few experiments have been carried out on its penetration through the human epidermal barrier and its possible biological effects in vivo and in vitro. In the frame of the NANODERM EU5 project, the penetration of TiO2-nanoparticles through the epidermis of human foreskin grafts transplanted into SCID mice was investigated in the Debrecen and Bordeaux nuclear microprobe laboratories using combined IBA techniques. Transmission electron microscope studies of the same samples were also carried out in the DMPFCS laboratory. The skin grafts were treated with a hydrophobic emulsion containing micronised TiO2-nanoparticles in occlusion, for different time periods. Quantitative elemental concentrations and distributions have been determined in 14-16 μm thick freeze-dried sections obtained from quick frozen punch biopsies using STIM, PIXE and RBS analytical methods. Using both microscopic methods, we have observed nanoparticles having penetrated into the corneocyte layers of stratum corneum by direct visualisation in TEM and via their chemical fingerprint in PIXE. The human skin xenograft has proved to be a model particularly well adapted to such penetration studies.

  19. Fabrication and surface-modification of implantable microprobes for neuroscience studies

    NASA Astrophysics Data System (ADS)

    Cao, H.; Nguyen, C. M.; Chiao, J. C.

    2012-06-01

    In this work implantable micro-probes for central nervous system (CNS) studies were developed on silicon and polyimide substrates. The probes which contained micro-electrode arrays with different surface modifications were designed for implantation in the CNS. The electrode surfaces were modified with nano-scale structures that could greatly increase the active surface area in order to enhance the electrochemical current outputs while maintaining micro-scale dimensions of the electrodes and probes. The electrodes were made of gold or platinum, and designed with different sizes. The silicon probes were modified by silicon nanowires fabricated with the vapor–liquid–solid mechanism at high temperatures. With polyimide substrates, the nanostructure modification was carried out by applying concentrated gold or silver colloid solutions onto the micro-electrodes at room temperature. The surfaces of electrodes before and after modification were observed by scanning electron microscopy. The silicon nanowire-modified surface was characterized by cyclic voltammetry. Experiments were carried out to investigate the improvement in sensing performance. The modified electrodes were tested with H2O2, electrochemical L-glutamate and dopamine. Comparisons between electrodes with and without nanostructure modification were conducted showing that the modifications have enhanced the signal outputs of the electrochemical neurotransmitter sensors.

  20. Application of a nuclear microprobe to the study of calcified tissues

    NASA Astrophysics Data System (ADS)

    Coote, Graeme E.; Vickridge, Ian C.

    1988-03-01

    The mineral fraction of calcified tissue is largely calcium hydroxyapatite (bones and teeth) or calcium carbonate (shells and fish otoliths). Apatite has such a strong affinity for fluoride ions that the F/Ca ratio can vary markedly with position in a bone or tooth, depending on the amount of fluoride present at the time of calcification or partial recrystallization. New biological information can be obtained by introducing extra fluoride into the diet of an animal and using a microprobe later to scan sections of bones or teeth. In suitable burial sites extra fluoride is introduced after death, and the new distribution may have applications in forensic science and archaeology. Fish otoliths are also of interest since a new carbonate layer is formed each day and the distribution of trace elements may record some aspects of the fish's life history. Results from the following studies are presented: fluorine distributions in the teeth of sheep which ingested extra fluoride for known periods; distributions of calcium and fluorine in femurs of rats which drank water high in fluoride for periods from 2 to 15 weeks; calcium and fluorine distributions in artificially-prepared lesions in tooth enamel; diffusion profiles in archaeological human teeth and animal bones; patterns in the strontium/calcium ratio in sectioned otoliths of several species of fish.

  1. The BioCAT Microprobe for X-Ray Fluorescence Imaging, MicroXAFS and Microdiffraction Studies on Biological Samples

    SciTech Connect

    Barrea, R.A.; Gore, D.; Kondrashkina, E.; Weng, T.; Heurich, R.; Vukonich, M.; Orgel, J.; Davidson, M.; Collingwood, J.F.; Mikhaylova, A.; Irving, T.C.

    2007-07-31

    Microbeam capabilities have been recently added to the Biophysics Collaborative Access Team (BioCAT) beamline 18-ID at the Advanced Photon Source to allow x-ray elemental mapping, micro x-ray absorption fine structure and microdiffraction studies on biological samples. The microprobe setup comprises a pair of platinum coated silicon KB mirrors; a sample holder mounted in a high precision positioner (100 nm accuracy); fluorescence detectors including a Si drift detector, Fe and Zn Bent Laue analyzers and a Ge detector; and a CCD detector for micro-diffraction experiments. The energy range of the microprobe is from 3.5 keV up to 17 keV. The fast scanning capabilities of the Bio-CAT beamline facilitate rapid acquisition of x-ray elemental images and micro-XAFS spectra. This paper reports the results of commissioning the KB mirror system and its performance in initial x-ray fluorescence mapping and micro-diffraction studies.

  2. Proton micro-probe analysis of framboidal pyrite and associated maceral types in a Devonian black shale

    SciTech Connect

    Graham, U.M.; Robl, T.L. . Center for Applied Energy Research); Robertson, J.D. . Dept. of Chemistry)

    1992-01-01

    Framboids are spherical, raspberry-like aggregates of pyrite which are typically associated with organic matter in black shales. Because framboids are often intimately intergrown with macerals of the kerogen in black shales the objectives of this study were to: (1) Select tramboidal pyrite with close spatial relationship to distinct maceral types; (2) Determine the trace-element variations within different maceral types and that of framboidal pyrite occurring adjacent to those macerals and; (3) Examine whether the S/Fe ratios of the tramboids vary based on different maceral-type association. This study investigates a Devonian-Mississippian black shale from East-Central Kentucky. The organic-rich matrix consists predominantly of bituminite, alginite and to lesser extent of vitrinite. Most framboids range between < 1[mu]m and 27 [mu]m in size and typically occur as clusters which are engulfed by lamellar flowing vitrinite, indicating that the framboids were already present before compaction. 161 PIXE-analyses were performed in both macerals and framboids. To understand the likelihood of framboid precursors in macerals the authors checked the constancy of the S, Fe and trace-element content in the immediate vicinity of the framboid particle. Moreover, the authors analyzed traverses through framboids associated with the three different maceral types. The S/Fe ratio of the framboids is always that of stoichiometric pyrite. The combined results suggest that the framboids may have formed independent of the sulfur and trace-element concentration among the macerals. Globular, partly translucent grains were observed to have great resemblances in size and trace-element contents compared to those of framboids. The S/Fe ratio of these grains was typically well in excess of 2.0 suggesting that the transparent matrix may have been a sulfur-rich phase that possibly serves as precursor for the framboids.

  3. Electron-microprobe study of chromitites associated with alpine ultramafic complexes and some genetic implications

    USGS Publications Warehouse

    Bird, M.L.

    1978-01-01

    Electron-microprobe and petrographic studies of alpine chromite deposits from around the world demonstrate that they are bimodal with respect to the chromic oxide content of their chromite. The two modes occur at 54 ? 4 and 37 ? 3 weight per cent chromic oxide corresponding to chromite designated as high-chromium and high-aluminum chromite respectively. The high-chromium chromite occurs exclusively with highly magnesian olivine (Fo92-97) and some interstitial diopside. The high-aluminum chromite is associated with more ferrous olivine (Fo88-92), diopside, enstatite, and feldspar. The plot of the mole ratios Cr/(Cr+Al+Fe3+) vs. Mg/(Mg+Fe2+) usually presented for alpine chromite is shown to have a high-chromium, high-iron to low-chromium, low-iron trend contrary to that shown by stratiform chromite. This trend is characteristic of alpine type chromite and is termed the alpine trend. However, a trend similar to that for startiform chromite is discernable on the graph for the high-chromium chromite data. This latter trend is well-developed at Red Mountain, Seldovia, Alaska. Analysis of the iron-magnesium distribution coefficient, Kd=(Fe/Mg)ol/(Fe/Mg)ch, between olivine and chromite shows that Kd for the high-chromium chromite from all ultramafic complexes has essentially the same constant value of .05 while the distribution coefficient for the high-aluminum chromite varies with composition of the chromite. These distribution coefficients are also characteristic of alpine-type chromites. The constant value for Kd for the high-chromium chromite and associated high-magnesium olivine in all alpine complexes suggests that they all crystallized under similar physico-chemical conditions. The two types of massive chromite and their associations of silicate minerals suggest the possibility of two populations with different origins. Recrystallization textures associated with the high-aluminum chromite together with field relationships between the gabbro and the chromite pods

  4. The laser microprobe mass analysis technique in the studies of the inner ear.

    PubMed

    Orsulakova, A; Morgenstern, C; Kaufmann, R; D'Haese, M

    1982-01-01

    Laser microprobe mass analysis (LAMMA) has been used to investigate cation and anion concentration in shock frozen, freeze-dried and plastic embedded inner ear tissue. Dissected inner ear specimens were prepared in various media of known ionic compositions and the influence on the K/Na ratio was measured in the lateral cochlea wall (spiral ligament, stria vascularis). For control purposes of the various procedures employed, muscle specimens (external standard) were processed in parallel. It was found that there is a good correlation between the K/Na ratio and the preservation of the tissue fine structure by comparing the results in tissues with different degrees of freezing damage. PMID:6764025

  5. Ion Microprobe Studies of Iodine Contents in Silicate Glasses and in Semarkona Chondrules

    NASA Astrophysics Data System (ADS)

    Goswami, J. N.; Sahijpal, S.; Swindle, T. D.; Musselwhite, D. S.; Grossman, J. N.

    1993-07-01

    Isotopic studies of electronegative elements (e.g. H, C, O, S, I, etc.) by the ion microprobe is best done in the negative secondary mode as the negative ion yields for these elements are much higher compared to their positive ion yields. However, analysis of non-conducting solids (e.g., silicates) in the negative secondary mode is beset with the problem of sample charging. In addition, for heavy elements like iodine, the problem of molecular interferences is also difficult to resolve. We have used a normal incidence electron gun, that generates a cloud of low energy electron near the sample surface, to overcome the problem of sample charging. The problem of molecular interferences was effectively removed by the energy filtering technique, commonly used for trace element studies [1]. Since the normal energy filtering procedure that involves introduction of appropriate offset to the sample high voltage cannot be followed in the negative secondary mode, we have introduced offset to the electrostatic analyzer (ESA) voltage, to achieve the required energy filtering. A silicon sample was analyzed to calibrate ESA voltage offset with sample voltage offset. We have initially analyzed silicon samples and a set of silicate glasses doped with iodine (0.1 to 1.5% by weight) to check for optimum conditions for measurement of low iodine concentration (

  6. An Ion Microprobe Study of Fractionated Sulfur Isotopes in Hydrothermal Sulfides of the Kaidun Meteorite Breccia

    NASA Astrophysics Data System (ADS)

    McSween, H. Y., Jr.; Riciputi, L. R.; Paterson, B. A.

    1996-03-01

    The Kaidun breccia contains diverse clasts of enstatite and carbonaceous chondrite, identified by their petrography and oxygen isotopic compositions. One distinctive lithology, classified as CM1 to reflect its CM parentage and highly altered state, contains texturally unusual pyrrhotite needles wrapped in sheaths of phyllosilicate, as well as aggregates and crosscutting veins of pentlandite. The unique textures and associated alteration minerals (serpentine, saponite, melanite garnet, framboidal magnetite) indicate that these sulfides formed in a precursor parent body by reactions with hydrothermal fluids at temperatures as high as 450 degrees C . The alteration conditions recorded by these clasts are extreme in comparison to other carbonaceous chondrites, and coated, jackstraw pyrrhotites are unknown from other meteorites. Thus, it is important to document the reaction products as completely as possible. Here we report the results of in situ analyses of sulfur isotopes in Kaidun pyrrhotite and pentlandite, obtained using a Cameca ims-4f ion microprobe.

  7. Proton decay studies at HRIBF

    SciTech Connect

    Batchelder, J. C.; Bingham, C. R.; Rykaczewski, K.; Toth, K. S.; Mas, J. F.; McConnell, J. W.; Yu, C.-H.; Davinson, T.; Slinger, R. C.; Woods, P. J.; Ginter, T. N.; Gross, C. J.; Grzywacz, R.; Kim, S. H.; Weintraub, W.; Janas, Z.; Karny, M.; MacDonald, B. D.; Piechaczek, A.; Zganjar, E. F.

    1998-12-21

    A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {mu}sec. In this paper we present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu.

  8. Proton decay studies at HRIBF

    SciTech Connect

    Batchelder, J.C.; Bingham, C.R.; Rykaczewski, K.; Toth, K.S.; Mas, J.F.; McConnell, J.W.; Yu, C.; Bingham, C.R.; Grzywacz, R.; Kim, S.H.; Weintraub, W.; Rykaczewski, K.; Janas, Z.; Karny, M.; Davinson, T.; Slinger, R.C.; Woods, P.J.; Ginter, T.N.; Gross, C.J.; MacDonald, B.D.; Piechaczek, A.; Zganjar, E.F.; Ressler, J.J.; Walters, W.B.; Szerypo, J.

    1998-12-01

    A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {mu}sec. In this paper we present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu. {copyright} {ital 1998 American Institute of Physics.}

  9. Study of metal bioaccumulation by nuclear microprobe analysis of algae fossils and living algae cells

    NASA Astrophysics Data System (ADS)

    Guo, P.; Wang, J.; Li, X.; Zhu, J.; Reinert, T.; Heitmann, J.; Spemann, D.; Vogt, J.; Flagmeyer, R.-H.; Butz, T.

    2000-03-01

    Microscopic ion-beam analysis of palaeo-algae fossils and living green algae cells have been performed to study the metal bioaccumulation processes. The algae fossils, both single cellular and multicellular, are from the late Neoproterozonic (570 million years ago) ocean and perfectly preserved within a phosphorite formation. The biosorption of the rare earth element ions Nd 3+ by the green algae species euglena gracilis was investigated with a comparison between the normal cells and immobilized ones. The new Leipzig Nanoprobe, LIPSION, was used to produce a proton beam with 2 μm size and 0.5 nA beam current for this study. PIXE and RBS techniques were used for analysis and imaging. The observation of small metal rich spores ( <10 μm) surrounding both of the fossils and the living cells proved the existence of some specific receptor sites which bind metal carrier ligands at the microbic surface. The bioaccumulation efficiency of neodymium by the algae cells was 10 times higher for immobilized algae cells. It confirms the fact that the algae immobilization is an useful technique to improve its metal bioaccumulation.

  10. Electron microprobe study of lunar and planetary zoned plagioclase feldspars: An analytical and experimental study of zoning in plagioclase

    NASA Technical Reports Server (NTRS)

    Smith, R. K.; Lofgren, G. E.

    1982-01-01

    Natural and experimentally grown zoned plagioclase feldspars were examined by electron microprobe. The analyses revealed discontinuous, sector, and oscillary chemical zoning superimposed on continuous normal or reverse zoning trends. Postulated mechanisms for the origin of zoning are based on either physical changes external to the magma (P, T, H2O saturation) or kinetic changes internal to the magma (diffusion, supersaturation, growth rate). Comparison of microprobe data on natural zoned plagioclase with zoned plagioclase grown in controlled experiments show that it may be possible to distinguish zonal development resulting from physio-chemical changes to the bulk magma from local kinetic control on the growth of individual crystals.

  11. Using synchrotron X-ray fluorescence microprobes in the study of metal homeostasis in plants

    PubMed Central

    Punshon, Tracy; Guerinot, Mary Lou; Lanzirotti, Antonio

    2009-01-01

    Background and Aims This Botanical Briefing reviews the application of synchrotron X-ray fluorescence (SXRF) microprobes to the plant sciences; how the technique has expanded our knowledge of metal(loid) homeostasis, and how it can be used in the future. Scope The use of SXRF microspectroscopy and microtomography in research on metal homeostasis in plants is reviewed. The potential use of SXRF as part of the ionomics toolbox, where it is able to provide fundamental information on the way that plants control metal homeostasis, is recommended. Conclusions SXRF is one of the few techniques capable of providing spatially resolved in-vivo metal abundance data on a sub-micrometre scale, without the need for chemical fixation, coating, drying or even sectioning of samples. This gives researchers the ability to uncover mechanisms of plant metal homeostasis that can potentially be obscured by the artefacts of sample preparation. Further, new generation synchrotrons with smaller beam sizes and more sensitive detection systems will allow for the imaging of metal distribution within single living plant cells. Even greater advances in our understanding of metal homeostasis in plants can be gained by overcoming some of the practical boundaries that exist in the use of SXRF analysis. PMID:19182222

  12. Using Synchrotron X-ray Fluorescence Microprobes in the Study of Metal Homeostasis in Plants

    SciTech Connect

    Punshon, T.; Guerinot, M; Lanzirotti, A

    2009-01-01

    Background and Aims: This Botanical Briefing reviews the application of synchrotron X-ray fluorescence (SXRF) microprobes to the plant sciences; how the technique has expanded our knowledge of metal(loid) homeostasis, and how it can be used in the future. Scope: The use of SXRF microspectroscopy and microtomography in research on metal homeostasis in plants is reviewed. The potential use of SXRF as part of the ionomics toolbox, where it is able to provide fundamental information on the way that plants control metal homeostasis, is recommended. Conclusions: SXRF is one of the few techniques capable of providing spatially resolved in-vivo metal abundance data on a sub-micrometre scale, without the need for chemical fixation, coating, drying or even sectioning of samples. This gives researchers the ability to uncover mechanisms of plant metal homeostasis that can potentially be obscured by the artefacts of sample preparation. Further, new generation synchrotrons with smaller beam sizes and more sensitive detection systems will allow for the imaging of metal distribution within single living plant cells. Even greater advances in our understanding of metal homeostasis in plants can be gained by overcoming some of the practical boundaries that exist in the use of SXRF analysis.

  13. Sulfide formation in reservoir carbonates of the Devonian Nisku Formation, Alberta, Canada: An ion microprobe study

    SciTech Connect

    Riciputi, L.R.; Cole, D.R.; Machel, H.G.

    1996-01-01

    The processes affecting sulfur during diagenesis in carbonates have been investigated by ion microprobe analysis of {sigma} {sup 34}S values of pyrite, marcasite, and anhydrite from the Devonian Nisku Formation in the Western Canada Sedimentary Basin. Pyrite and marcasite from three Nisku wells have {sigma}{sup 34}S ranging between -35 and +20{per_thousand}. The {sigma}{sup 34}S values increase b6y up to 50{per_thousand} with increasing well depth in two different Nisku wells, and {sigma}{sup 34}S also increases by up to 15{per_thousand} as grain size increases form 40 to over 100 {mu}m in individual samples. The appearance of native sulfur is accompanied by an increase of up to 30{per_thousand} in pyrite {sigma}{sup 34}S values. Bulk and ion probe analyses of anhydrite are relatively uniform ({sigma}{sup 34}S = +22 to +30{per_thousand} CDT). The predominately low {sigma}{sup 34}S values of Nisku sulfides indicate bacterial sulfate reduction. Textural relations indicate that Fe-sulfide formation in Nisku carbonates may have occurred by two different mechanisms. Much of the sulfide has {sigma}{sup 34}S values that suggest that it was associated with bacterial sulfate reduction, although most Fe-sulfides did not form until after pervasive matrix dolomitization (depths of 300-1000 m). Other sulfide may have formed later, during deep ({approximately}4km) burial via thermochemical sulfate reduction. The range in {sigma}{sup 34}S values in a single thin section and correlations between pyrite morphology and isotopic values suggest that sulfate reduction was a very localized process, and that the sulfate reduction environment varied considerably on a small scale. 61 refs., 10 figs., 1 tab.

  14. Impact history of the Chelyabinsk meteorite: Electron microprobe and LA-ICP-MS study of sulfides and metals

    NASA Astrophysics Data System (ADS)

    Andronikov, A. V.; Andronikova, I. E.; Hill, D. H.

    2015-12-01

    Electron microprobe and LA-ICP-MS study of sulfides and metals from two fragments of the LL5 Chelyabinsk meteorite were conducted. The fragments are impact breccias, one fragment contains both chondritic and shock vein lithologies, and the other contains shock-darkened chondritic clasts and vesicular impact melts. The chondritic lithology and shock veins display very similar opaque mineral compositions. The mineral compositions in the impact-melt breccias are distinctly different. The brecciated state of the Chelyabinsk meteorite suggests strong involvement of shock-related processes during the evolution of the parent body. Multiple heavy impact events occurred on the parent asteroid and on the Chelyabinsk meteoroid itself over the time period from ca. 4.5 Ga until ca. 1.2 Ma. The shock veins were produced in situ on the parent body. The impact-melt breccias could have formed because of the dramatic impact to the parent LL-chondrite body that could be partly disintegrated. The fragment containing shock-darkened chondritic clasts and vesicular impact melt lithologies preserves a record of melting, volatilization, partial degassing, and quenching of the molten material. The abundance and size (up to 1 mm) of the vesicles suggest that the impact melt must have been buried at some depth after formation. After impact and subsequent melting occurred, the impact-induced pressure on the shallow asteroid interior was released that caused "boiling" of volatiles and generation of S-rich bubbles. Such an impact excavated down to depths of the body generating multiple fragments with complicated histories. These fragments reaccumulated into a gravitational aggregate and formed the parental meteoroid for the Chelyabinsk meteorite.

  15. Petrology of Apollo 14 regolith breccias and ion microprobe studies of glass beads

    NASA Technical Reports Server (NTRS)

    Simon, S. B.; Papike, J. J.; Shearer, C. K.; Hughes, S. S.; Schmitt, R. A.

    1989-01-01

    Mineral chemistries, glass chemistries, and bulk compositions of Apollo 14 regolith beccias are used to study the regolith evolution at the Apollo 14 site and on the moon in general. Major changes in the regolith since the formation of the breccias include an increase in maturity, an increase in glasses with the Fra Mauro basalt composition, and decreases in feldspathic and mare glasses. The results suggest the presence of a source with a larger non-KREEPy highland plutonic component than other breccias.

  16. Broad Beam and Ion Microprobe Studies of Single-Event Upsets in High Speed 0.18micron Silicon Germanium Heterojunction Bipolar Transistors and Circuits

    NASA Technical Reports Server (NTRS)

    Reed, Robert A.; Marshall, Paul W.; Pickel, Jim; Carts, Martin A.; Irwin, TIm; Niu, Guofu; Cressler, John; Krithivasan, Ramkumar; Fritz, Karl; Riggs, Pam

    2003-01-01

    SiGe based technology is widely recognized for its tremendous potential to impact the high speed microelectronic industry, and therefore the space industry, by monolithic incorporation of low power complementary logic with extremely high speed SiGe Heterojunction Bipolar Transistor (HBT) logic. A variety of studies have examined the ionizing dose, displacement damage and single event characteristics, and are reported. Accessibility to SiGe through an increasing number of manufacturers adds to the importance of understanding its intrinsic radiation characteristics, and in particular the single event effect (SEE) characteristics of the high bandwidth HBT based circuits. IBM is now manufacturing in its 3rd generation of their commercial SiGe processes, and access is currently available to the first two generations (known as and 6HP) through the MOSIS shared mask services with anticipated future release of the latest (7HP) process. The 5 HP process is described and is characterized by a emitter spacing of 0.5 micron and a cutoff frequency ff of 50 GHz, whereas the fully scaled 7HP HBT employs a 0.18 micron emitter and has an fT of 120 GHz. Previous investigations have the examined SEE response of 5 HP HBT circuits through both circuit testing and modeling. Charge collection modeling studies in the 5 H P process have also been conducted, but to date no measurements have been reported of charge collection in any SiGe HBT structures. Nor have circuit models for charge collection been developed in any version other than the 5 HP HBT structure. Our investigation reports the first indications of both charge collection and circuit response in IBM s 7HP-based SiGe process. We compare broad beam heavy ion SEU test results in a fully function Pseudo-Random Number (PRN) sequence generator up to frequencies of 12 Gbps versus effective LET, and also report proton test results in the same circuit. In addition, we examine the charge collection characteristics of individual 7HP HBT

  17. JSC Mars-1 Martian Soil Simulant: Melting Experiments and Electron Microprobe Studies

    NASA Technical Reports Server (NTRS)

    Carpenter, P.; Sebille, L.; Boles, W.; Chadwell, M.; Schwarz, L.

    2003-01-01

    JSC Mars-1 has been developed as a Martian regolith simulant, and is the <1 mm size fraction of a palagonitic tephra (a glassy volcanic ash altered at low temperatures) from Pu'u Nene cinder cone on the Island of Hawaii. The Mars-1 simulant forms the basis for numerous terrestrial studies which aim to evaluate the suitability of Martian soil for materials processing. Martian soil may be sintered to form building materials for construction, and also melted or reacted to extract metals for various uses, as well as oxygen for life support.

  18. Synchrotron x-ray and electron micro-probe study of contaminated dredged sediments.

    NASA Astrophysics Data System (ADS)

    Poitevin, A.; Lerouge, C.; Wille, G.; Bataillard, P.; Hennet, L.

    2012-04-01

    Sediments originating from periodic dredging of waterways were traditionally disposed of in storage sites without any precautions or treatments. There may be some environmental concerns especially when the dredged material comes from historically contaminated areas such as the North French coal basin. This study aims to characterize the metal mobility (mainly Zn and Pb) in deposited dredged sediments by combining chemical and spectroscopic techniques. The sediments consist of a silty fraction (~ 40 %: dominant quartz, minor feldspar), carbonates and a clay fraction (illite dominant, illite-smectite mixed layer, kaolinite). This mineralogical heterogeneity and the observed grain-size distribution (70 to 80 % wt of the total sediment is <50µm) lead to a need to use microbeam techniques to identify Zn and Pb carriers. Electron probe micro-analyse (EPMA) combined with microbeam x-ray fluorescence (µXRF) at Synchrotron sources were used to identify Zn and Pb carriers. In particular Zn and Pb distributions in thin-section samples were determined by µ-XRF elemental mappings. EPMA was used to determine the distribution of light elements for which the energy of the emission lines is below 4 keV (Si, S, P…). The presence of reduced (sulphides) and oxidized (sulphates, oxihydroxides) phases strongly suggests that the redox state is one of the major parameters controlling the metal mobility. Therefore x-ray absorption spectroscopy experiments were also performed to study the oxidation state in both bulk samples and on selected regions of interest in thin section samples. Preliminary chemical analyses In this work, the potential effects of the sample preparation on phase's structure and redox state were also studied and will be presented. In particular measurements using x-ray absorption spectroscopy were carried out on air dried or lyophilised powders and on samples stored in a cryogenic environment after sampling. For the latter, we studied the evolution of the iron

  19. X-ray microprobe studies of Hungarian background and urban aerosols

    SciTech Connect

    Toeroek, S.; Sandor, S. . Central Research Inst. for Physics); Xhoffer, C.; Van Grieken, R. . Dept. of Chemistry); Jones, K.W. ); Sutton, S.R.; Rivers, M.L. )

    1991-10-01

    In order to determine the polluting atmospheric sources in urban and background areas source apportionment of the air particulate matter is necessary. Hitherto these studies were mostly based on bulk composition measurements of the aerosol. Source profiles, i.e. the concentrations of several elements for air particulate matter originating from one source, can be deduced from the receptor data using a number of multivariate techniques among which the chemical mass balance. The application is limited by the large number of observations that must be made for each of the variables. Often an elaborated sample preparation is necessary for fractionating the sample into several sub samples, according to the density, particle diameter or other relevant properties. Often this may results in poorly resolved source profiles. The aim of the present work is to find the relative abundance of the particle types originating from two different background monitoring stations in the middle of the Great Hungarian Plain. In urban areas most pollutants originate from traffic and municipal waste incineration. Since heavy metals play an important role in these samples the highly sensitive x-ray microscope (XRM) of the National Synchrotron Light Source (NSLS) of the Brookhaven National Laboratory was used. A feasibility study on individual aerosol particles sampled at the above background stations and in the urban area of Budapest is discussed.

  20. An ion microprobe study of CAIs from CO3 meteorites. [Abstract only

    NASA Technical Reports Server (NTRS)

    Russell, S. S.; Greenwood, R. C.; Fahey, A. J.; Huss, G. R.; Wasserburg, G. J.

    1994-01-01

    When attempting to interpret the history of Ca, Al-rich inclusions (CAIs) it is often difficult to distinguish between primary features inherited from the nebula and those produced during secondary processing on the parent body. We have undertaken a systematic study of CAIs from 10 CO chondrites, believed to represent a metamorphic sequence with the goal of distinguishing primary and secondary features. ALHA 77307 (3.0), Colony (3.0), Kainsaz (3.1), Felix (3.2), ALH 82101 (3.3), Ornans (3.3), Lance (3.4), ALHA 77003 (3.5), Warrenton (3.6), and Isna (3.7) were examined by Scanning Electron Microscopy (SEM) and optical microscopy. We have identified 141 CAIs within these samples, and studied in detail the petrology of 34 inclusions. The primary phases in the lower petrologic types are spinel, melilite, and hibonite. Perovskite, FeS, ilmenite, anorthite, kirschsteinite, and metallic Fe are present as minor phases. Melilite becomes less abundant in higher petrologic types and was not detected in chondrites of type 3.5 and above, confirming previous reports that this mineral easily breaks down during heating. Iron, an element that would not be expected to condense at high temperatures, has a lower abundance in spinel from low-petrologic-type meteorites than those of higher grade, and CaTiO3 is replaced by FeTiO3 in meteorites of higher petrologic type. The abundance of CAIs is similar in each meteorite. Eight inclusions have been analyzed by ion probe. The results are summarized. The results obtained to date show that CAIs in CO meteorites, like those from other meteorite classes, contain Mg* and that Mg in some inclusions has been redistributed.

  1. Asymmetric Distribution of Metals in the Xenopus Laevis Oocyte: a Synchrotron X-Ray Fluorescence Microprobe Study

    SciTech Connect

    Popescu, B.F.Gh.; Belak, Z.R.; Ignatyev, K.; Ovsenek, N.; Nichol, H.

    2009-06-04

    The asymmetric distribution of many components of the Xenopus oocyte, including RNA, proteins, and pigment, provides a framework for cellular specialization during development. During maturation, Xenopus oocytes also acquire metals needed for development, but apart from zinc, little is known about their distribution. Synchrotron X-ray fluorescence microprobe was used to map iron, copper, and zinc and the metalloid selenium in a whole oocyte. Iron, zinc, and copper were asymmetrically distributed in the cytoplasm, while selenium and copper were more abundant in the nucleus. A zone of high copper and zinc was seen in the animal pole cytoplasm. Iron was also concentrated in the animal pole but did not colocalize with zinc, copper, or pigment accumulations. This asymmetry of metal deposition may be important for normal development. Synchrotron X-ray fluorescence microprobe will be a useful tool to examine how metals accumulate and redistribute during fertilization and embryonic development.

  2. Asymmetri Distribution of Metals in the Xenopus Laevis Oocyte: a Synchrotron X-Ray Fluorescence Microprobe Study

    SciTech Connect

    Popescu, B.F.G.; Belak, Z.R.; Ignatyev, K.; Ovsenek, N.; Nichol, H.; /Saskatchewan U. /SLAC, SSRL

    2009-04-29

    The asymmetric distribution of many components of the Xenopus oocyte, including RNA, proteins, and pigment, provides a framework for cellular specialization during development. During maturation, Xenopus oocytes also acquire metals needed for development, but apart from zinc, little is known about their distribution. Synchrotron X-ray fluorescence microprobe was used to map iron, copper, and zinc and the metalloid selenium in a whole oocyte. Iron, zinc, and copper were asymmetrically distributed in the cytoplasm, while selenium and copper were more abundant in the nucleus. A zone of high copper and zinc was seen in the animal pole cytoplasm. Iron was also concentrated in the animal pole but did not colocalize with zinc, copper, or pigment accumulations. This asymmetry of metal deposition may be important for normal development. Synchrotron X-ray fluorescence microprobe will be a useful tool to examine how metals accumulate and redistribute during fertilization and embryonic development.

  3. Feasibility study of a lunar landing area navigation network deployed by impacting micro-probes

    NASA Astrophysics Data System (ADS)

    Weiss, P.; Yung, K. L.

    2010-05-01

    Exploration activities on the lunar surface will require precise knowledge of the position of a robotic or manned vehicle. This paper discusses the use of radio beacons as method to determine the position of a mobile unit on the surface. Previous concepts consider the installation of such equipment by the robot itself. A novel idea is discussed here, namely to use miniaturized radio beacons which are deployed (released) during the descent of the lander on the surface. This idea has three major advantages compared to previous proposals: (i) it avoids the time costly and energy consuming installation of the equipment by a rover. (ii) The impact velocities of the probes are in reasonable range since the probes are deployed at low altitude from the main lander that approaches its final landing site. (iii) The probes can take reconnaissance pictures during their free-fall to the surface. This method will therefore deliver charts of the proximity of the landing area with higher resolution than those done by orbital means. Such information will enable scientists and mission operators to precisely plan robotic excursions (and later Extra Vehicular Activity) through the identification of hazardous areas and spots of interest. The paper will study the feasibility of this system from different aspects. The first section will outline the application scenario and the potential outcome of such a system for the coming phase of lunar exploration. A technological readiness review was done to evaluate if the payload instrumentation for these high velocity impacting probes is available. The second section presents the simulation of the impact process of a preliminary probe model in nonlinear transient dynamic finite element analysis using the Lagrangian hydrocode LS-DYNA. The purpose of this simulation was to evaluate if the beacon is able to communicate with the mobile unit even when buried into the soil. The integration of this payload into coming lunar missions will contribute to

  4. Mars Microprobe Entry Analysis

    NASA Technical Reports Server (NTRS)

    Braun, Robert D.; Mitcheltree, Robert A.; Cheatwood, F. McNeil

    1998-01-01

    The Mars Microprobe mission will provide the first opportunity for subsurface measurements, including water detection, near the south pole of Mars. In this paper, performance of the Microprobe aeroshell design is evaluated through development of a six-degree-of-freedom (6-DOF) aerodynamic database and flight dynamics simulation. Numerous mission uncertainties are quantified and a Monte-Carlo analysis is performed to statistically assess mission performance. Results from this 6-DOF Monte-Carlo simulation demonstrate that, in a majority of the cases (approximately 2-sigma), the penetrator impact conditions are within current design tolerances. Several trajectories are identified in which the current set of impact requirements are not satisfied. From these cases, critical design parameters are highlighted and additional system requirements are suggested. In particular, a relatively large angle-of-attack range near peak heating is identified.

  5. Simulation study of proton transport in ionomers

    NASA Astrophysics Data System (ADS)

    Taylor, Philip; Allahyarov, Elshad

    2008-03-01

    Coarse-grained molecular-dynamics simulations were used to study the morphological changes induced in a Nafion-like ionomer by the imposition of a strong electric field. We observe that proton transport through this polymer electrolyte membrane is accompanied by morphological changes that include the formation of structures aligned along the direction of the applied field. The polar head groups of the ionomer side chains assemble into clusters, which then form rod-like formations, and these cylindrical structures then assemble into a hexagonally ordered array aligned with the direction of current flow. For dry ionomers, at current densities in excess of 1 A/cm^2 these rod-like clusters undergo an inner micro-phase separation, in which distinct wire-like lines of sulfonate head groups are accompanied by similar wire-like alignments of bound protons. The clusters appear to be of two types. If there are two, four, or five lines of sulfonates then there is an equal number of lines of protons, but if there are three lines of sulfonates then they are accompanied by four lines of protons. Occasionally these lines of sulfonates and protons form a helical structure. Upon removal of the electric field, the hexagonal array of rod-like structures remains, but the microphase separation disappears below the threshold current of 1 A/cm^2.

  6. Histological changes induced by 15 F CO2 laser microprobe especially designed for root canal sterilization: an in-vivo study

    NASA Astrophysics Data System (ADS)

    Kesler, Gavriel; Koren, Rumelia; Gal, Rivka

    1998-04-01

    Until now, no suitable delivery fiber existed for CO2 laser endodontic radiation in the apical region where it is most difficult to eliminate the pulp tissue using conventional methods. To overcome this problem, we designed a microprobe that reaches closer to the apex, distributing the energy density to a smaller area of the root canal, thus favorably increasing the thermal effects. The 15 F CO2 microprobe is a flexible, hollow, metal fiber, 300 micrometer in diameter and 20 mm in length, coupled onto a handpiece, with the following radiation parameters: wavelength -- 10.6 micrometer; pulse duration -- 50m/sec; energy per pulse 0.25 joule; energy density -- 353.7J/cm2 per pulse; power on tissue -- 5 W. The study was conducted on 30 vital maxillary or mandibulary; central, lateral, or premolar teeth destined for extraction due to periodontal problems. Twenty were experimentally treated with pulsed CO2 laser delivered by this newly developed fiber after conventional root canal preparation. Temperature measured at three points on the root surface during laser treatment did not exceed 38 degrees Celsius. Ten teeth represented the control group in which only root canal preparation was performed in the conventional method. Histological examination of the laser treated teeth showed coagulation necrosis and vacuolization of remaining pulp tissue in the root canal periphery. Primary and secondary dentin appeared normal, in all cases treated with 15 F CO2 laser. Gramm stain and bacteriologic examination revealed complete sterilization. These results demonstrate the unique capabilities of this special microprobe in sterilization of the root canal, and no thermal damage to the surrounding tissue.

  7. An ion microprobe study of individual zircon phenocrysts from voluminous post-caldera rhyolites of the Yellowstone caldera

    NASA Astrophysics Data System (ADS)

    Watts, K. E.; Bindeman, I. N.; Schmitt, A. K.

    2010-12-01

    Following the formation of the Yellowstone caldera from the 640 ka supereruption of the Lava Creek Tuff (LCT), a voluminous episode of post-caldera volcanism filled the caldera with >600 km3 of low-δ18O rhyolite. Such low-δ18O signatures require remelting of 100s of km3 of hydrothermally altered (18O-depleted) rock in the shallow crust. We present a high resolution oxygen isotope and geochronology (U-Th and U-Pb) study of individual zircon crystals from seven of these voluminous post-caldera rhyolites in order to elucidate their genesis. Oxygen isotope and geochronology analyses of zircon were performed with an ion microprobe that enabled us to doubly fingerprint 25-30 µm diameter spots. Host groundmass glasses and coexisting quartz were analyzed in bulk for oxygen isotopes by laser fluorination. We find that zircons from the youngest (200-80 ka) post-caldera rhyolites have oxygen isotopic compositions that are in equilibrium with low-δ18O host groundmass glasses and quartz and are unzoned in oxygen and U-Th age. This finding is in contrast to prior work on older (500-250 ka) post-caldera rhyolites, which exhibit isotopic disequilibria and age zoning, including the presence of clearly inherited zircon cores. Average U-Th crystallization ages and δ18O zircon values for Pitchstone Plateau flow (81±7 ka, 2.8±0.2‰), West Yellowstone flow (118±8 ka, 2.8±0.1‰), Elephant Back flow (175±22 ka, 2.7±0.2‰) and Tuff of Bluff Point (176±20 ka, 2.7±0.1‰) are overlapping or nearly overlapping in age and identical in oxygen isotope composition within uncertainty (2 SE). New U-Pb geochronology and oxygen isotope data for the North Biscuit Basin flow establish that it has an age (188±33 ka) and δ18O signature (2.8±0.2‰) that is distinctive of the youngest post-caldera rhyolites. Conversely, the South Biscuit Basin flow has a heterogeneous zircon population with ages that range from 550-250 ka. In this unit, older and larger (200-400 µm) zircons have more

  8. Ion Beam Induced Charge Collection (IBICC) Studies and Focused Heavy Ion Microprobe Facility at the University of North Texas

    NASA Astrophysics Data System (ADS)

    Guo, B. N.; Renfrow, S. N.; Jin, J.; Hughes, B. F.; Duggan, J. L.; McDaniel, F. D.

    1998-03-01

    As the feature sizes reduce, semiconductor devices increase their sensitivity to ionizing radiation that creates electron-hole pairs. The induced charge collection by the device p-n junctions can alter the state of the device, most commonly causing memory errors. To design robust devices immune to these effects, it is essential to create and test accurate models of this process. Such model-based testing requires energetic heavy ions whose number, arrival time, spatial location, energy, and angle can be controlled when they strike the integrated circuit. IBMAL is building a strong focusing lens system with spatial resolution 1μ m, raster-scanning capabilities for alpha particles and heavier ions. A detailed description of the focused heavy ion microprobe facility and IBICC experimental results conducted at Sandia National Laboratory will be presented.

  9. Experimental determination of the partitioning of gallium between solid iron metal and synthetic basaltic melt Electron and ion microprobe study

    NASA Technical Reports Server (NTRS)

    Drake, M. J.; Newsom, H. E.; Reed, S. J. B.; Enright, M. C.

    1984-01-01

    The distribution of Ga between solid Fe metal and synthetic basaltic melt is investigated experimentally at temperatures of 1190 and 1330 C, and over a narrow range of oxygen fugacities. Metal-silicate reversal experiments were conducted, indicating a close approach to equilibrium. The analysis of the partitioned products was performed using electron and ion microprobes. At one bar total pressure, the solid metal/silicate melt partition coefficient D(Ga) is used to evaluate metal-silicate fractionation processes in the earth, moon, and Eucrite Parent Body (EPB). It is found that the depletion of Ga abundances in the EPB is due to the extraction of Ga into a metallic core. Likewise, the depletion of Ga in the lunar mantle is consistent with the extraction of Ga into a smaller lunar core if Ga was originally present in a subchondritic concentration. The relatively high Ga abundances in the earth's mantle are discussed, with reference to several theoretical models.

  10. A study of the behavior of bromide in artificial pits using in situ X-ray microprobe analysis

    SciTech Connect

    Isaacs, H.S.; Kaneko, M.

    1997-12-31

    An in situ X-ray microprobe analysis of Type 316 stainless steel artificial pits has been carried out with a bromide/chloride solution. A high intensity 8 micron diameter polychromatic X-ray beam was scanned across the steel solution interface within the artificial pit. The resulting X-ray fluorescence was analyzed using an energy dispersive X-ray detector. In contrast to the light Cl atom, Br could be detected, making it possible to monitor the behavior of halides in the artificial pits and in the salt layer at the interface. It was found that Br was more active than Cl. At high potentials, elemental Br was produced as an oxidation product, whereas without added bromide, chloride only formed a salt layer. Br also concentrated at the salt steel interface at potentials below where it was oxidized.

  11. Zircon geochronology and ca. 400 Ma exhumation of Norwegian ultrahigh-pressure rocks: An ion microprobe and chemical abrasion study

    USGS Publications Warehouse

    Root, D.B.; Hacker, B.R.; Mattinson, J.M.; Wooden, J.L.

    2004-01-01

    Understanding the formation and exhumation of the remarkable ultrahigh-pressure (UHP) rocks of the Western Gneiss Region, Norway, hinges on precise determination of the time of eclogite recrystallization. We conducted detailed thermal ionization mass spectrometry, chemical abrasion analysis and sensitive high-resolution ion-microprobe analysis of zircons from four ultrahigh- and high-pressure (HP) rocks. Ion-microprobe analyses from the Flatraket eclogite yielded a broad range of apparently concordant Caledonian ages, suggesting long-term growth. In contrast, higher precision thermal ionization mass spectrometry analysis of zircon subject to combined thermal annealing and multi-step chemical abrasion yielded moderate Pb loss from the first (lowest temperature) abrasion step, possible minor Pb loss or minor growth at 400 Ma from the second step and a 407-404 Ma cluster of slightly discordant 206Pb/238U ages, most likely free from Pb loss, from the remaining abrasion steps. We interpret the latter to reflect zircon crystallization at ???405-400 Ma with minor discordance from inherited cores. Zircon crystallization occurred at eclogite-facies, possibly post-peak conditions, based on compositions of garnet inclusions in zircon as well as nearly flat HREE profiles and lack of Eu anomalies in zircon fractions subjected to chemical abrasion. These ages are significantly younger than the 425 Ma age often cited for western Norway eclogite recrystallization, implying faster rates of exhumation (>2.5-8.5 km/Myr), and coeval formation of eclogites across the UHP portion of the Western Gneiss Region. ?? 2004 Published by Elsevier B.V.

  12. Nuclear microprobe analysis of lead profile in crocodile bones

    NASA Astrophysics Data System (ADS)

    Orlic, I.; Siegele, R.; Hammerton, K.; Jeffree, R. A.; Cohen, D. D.

    2003-09-01

    Elevated concentrations of lead were found in Australian free ranging saltwater crocodile ( Crocodylus porosus) bone and flesh. Lead shots were found as potential source of lead in these animals. ANSTO's heavy ion nuclear microprobe was used to measure the distribution of Pb in a number of bones and osteoderms. The aim was to find out if elevated Pb concentration remains in growth rings and if the concentration is correlated with the blood levels recorded at the time. Results of our study show a very distinct distribution of accumulated Pb in bones and osteoderms as well as good correlation with the level of lead concentration in blood. To investigate influence of ion species on detection limits measurements of the same sample were performed by using 3 MeV protons, 9 MeV He ions and 20 MeV carbon ions. Peak to background ratios, detection limits and the overall 'quality' of obtained spectra are compared and discussed.

  13. Intracochlear microprobe analysis

    SciTech Connect

    Bone, R.C.; Ryan, A.F.

    1982-04-01

    Energy dispersive x-ray analysis (EDXA) or microprobe analysis provides cochlear physiologists with a means of accurately assessing relative ionic concentrations in selected portions of the auditory mechanism. Rapid freezing followed by lyophilization allows the recovery of fluid samples in crystalline form not only from perilymphatic and endolymphatic spaces, but also from much smaller subregions of the cochlea. Because samples are examined in a solid state, there is no risk of diffusion into surrounding or juxtaposed fluids. Samples of cochlear tissues may also be evaluated without the danger of intercellular ionic diffusion. During direct visualization by scanning electron microscopy, determination of the biochemical makeup of the material being examined can be simultaneously, assuring the source of the data collected. Other potential advantages and disadvantages of EDXA are reviewed. Initial findings as they relate to endolymph, perilymph, stria vascularis, and the undersurface of the tectorial membrane are presented.

  14. A method based on Monte Carlo simulations and voxelized anatomical atlases to evaluate and correct uncertainties on radiotracer accumulation quantitation in beta microprobe studies in the rat brain

    NASA Astrophysics Data System (ADS)

    Pain, F.; Dhenain, M.; Gurden, H.; Routier, A. L.; Lefebvre, F.; Mastrippolito, R.; Lanièce, P.

    2008-10-01

    The β-microprobe is a simple and versatile technique complementary to small animal positron emission tomography (PET). It relies on local measurements of the concentration of positron-labeled molecules. So far, it has been successfully used in anesthetized rats for pharmacokinetics experiments and for the study of brain energetic metabolism. However, the ability of the technique to provide accurate quantitative measurements using 18F, 11C and 15O tracers is likely to suffer from the contribution of 511 keV gamma rays background to the signal and from the contribution of positrons from brain loci surrounding the locus of interest. The aim of the present paper is to provide a method of evaluating several parameters, which are supposed to affect the quantification of recordings performed in vivo with this methodology. We have developed realistic voxelized phantoms of the rat whole body and brain, and used them as input geometries for Monte Carlo simulations of previous β-microprobe reports. In the context of realistic experiments (binding of 11C-Raclopride to D2 dopaminergic receptors in the striatum; local glucose metabolic rate measurement with 18F-FDG and H2O15 blood flow measurements in the somatosensory cortex), we have calculated the detection efficiencies and corresponding contribution of 511 keV gammas from peripheral organs accumulation. We confirmed that the 511 keV gammas background does not impair quantification. To evaluate the contribution of positrons from adjacent structures, we have developed β-Assistant, a program based on a rat brain voxelized atlas and matrices of local detection efficiencies calculated by Monte Carlo simulations for several probe geometries. This program was used to calculate the 'apparent sensitivity' of the probe for each brain structure included in the detection volume. For a given localization of a probe within the brain, this allows us to quantify the different sources of beta signal. Finally, since stereotaxic accuracy is

  15. An ion microprobe study of the intra-crystalline behavior of REE and selected trace elements in pyroxene from mare basalts with different cooling and crystallization histories

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; Papike, J. J.; Simon, S. B.; Shimizu, N.

    1989-01-01

    The effects of crystallization interaction on the trace element zoning characteristics of pyroxenes are analyzed using electron and ion microprobe techniques. Four pigeonite basalts with similar isochemical composition, but different cooling rates and crystallization histories are studied. Pyroxene quadrilaterals displaying crystallization trends are presented. The crystal chemical rationalization of REE zoning, pattern shapes, and abundances are examined. The data reveal that the trace element zoning characteristics in pyroxene and the partitioning of trace elements between pyroxene and the melt are related to the interaction between the efficiency of the crystallization process, the kinetics at the crystal-melt interface, the kinetics of plagioclase nucleation and the characteristics of the crystal chemical substitutions in the pyroxene and the associated crystallizing phase.

  16. Positron microprobe at LLNL

    SciTech Connect

    Asoka, P; Howell, R; Stoeffl, W

    1998-11-01

    The electron linac based positron source at Lawrence Livermore National Laboratory (LLNL) provides the world's highest current beam of keV positrons. We are building a positron microprobe that will produce a pulsed, focused positron beam for 3-dimensional scans of defect size and concentration with sub-micron resolution. The widely spaced and intense positron packets from the tungsten moderator at the end of the 100 MeV LLNL linac are captured and trapped in a magnetic bottle. The positrons are then released in 1 ns bunches at a 20 MHz repetition rate. With a three-stage re-moderation we will compress the cm-sized original beam to a 1 micro-meter diameter final spot on the target. The buncher will compress the arrival time of positrons on the target to less than 100 ps. A detector array with up to 60 BaF2 crystals in paired coincidence will measure the annihilation radiation with high efficiency and low background. The energy of the positrons can be varied from less than 1 keV up to 50 keV.

  17. An ion and electron microprobe study of amphibole in the Garland Peak Syenite, Red Hill Complex, NH

    SciTech Connect

    Dorais, M.J. ); Macrae, N.D. )

    1992-01-01

    The Garland Peak Syenite (GPS) of the Red Hill complex, NH, consists predominantly of amphibole, oligoclase, perthite, and quartz; amphiboles are zoned from kaersutite cores to hastingsite-hornblende rims. The association of kaersutite with quartz indicates that the GPS magma experienced substantial changes in silica activity during its crystallization history. Camptonites are also associated with the Red Hill complex, and in order to elucidate the camptonite-GPS, and the GPS kaersutite-quartz relationships, amphiboles in these rocks were analyzed by electron and ion microprobe techniques. Kaersutites in the camptonites and GPS are very similar in terms of major and minor elements. REE concentrations in the camptonite's kaersutite are slightly less than the GPS kaersutite; LREE abundances are 100 times chondrites, La/Yb values are 4--5. GPS kaersutitic cores have LREE abundances between 200--300 times chondrites with La/Yb values between 6--8. Compared to the cores, the hastingsite rims are preferentially enriched in REE with LREE between 1,000 and 2,000 times chondrites, La/Yb values range between 16--18, and the patterns have large negative Eu anomalies. Although complicated by the certainty of changing partition coefficients during crystallization, the enrichment in total REE from camptonite--GPS kaersutite--GPS hastingsite is consistent with a differentiation origin of the suite. Rimward depletions in Sr, Eu, V, and Ti concentrations, and the increase in La/Yb values suggest that parental camptonites fractionated amphibole, magnetite, and feldspar to produce silica-oversaturated GPS liquids. The significance of amphibole and magnetite fractionation on camptonite-GPS silica activity is also indicated by bulk-rock, major element modeling.

  18. A combined electron microprobe (EMP) and Raman spectroscopic study of the alteration products in Martian meteorite MIL 03346

    NASA Astrophysics Data System (ADS)

    Kuebler, K. E.

    2013-03-01

    We examine the secondary alteration products in MIL 03346 using Raman spectroscopic and electron microprobe traverses. Discussion focuses on the single olivine in ,177 supplemented with observations from ,168 and ,169. Traverses start at the rim and progress into the interior. Dark brown, nearly opaque, laihunite [Fe2+Fe3+2(SiO4)2] is present as overgrowths, and 20-50 µm veins of reddish-brown stilpnomelane [(K,Na,Ca)4(Ti0.1,Al2.3,Fe3+35.5,Mn0.8,Mg9.3) (Si63Al9)(O,OH)206∗n(H2O)] occur inside the olivine. Stilpnomelane crosscuts and postdates the laihunite; veins are in sharp contact with the host olivine but lined by ~5 µm films of jarosite [KFe3+3(SO4)2(OH)6] from a later generation of alteration. An interstitial laihunite also hosts stilpnomelane. The most recent secondary phases are gypsum and bassanite in our X-ray maps of ,168 and ,169. Ca-sulfates were not observed in X-ray maps of ,177 but were detected in our Raman point count. All sulfates are believed to be Martian. The groundmass of MIL indicates rapid cooling from elevated temperatures with fO2 near QFM. Reports of laihunite synthesis by olivine oxidation at elevated temperatures (100-800°C) suggest the overgrowths formed during consolidation. In terrestrial rocks, stilpnomelane is a product of late diagenesis to garnet-grade metamorphism. In MIL, stilpnomelane appears to be a secondary phase formed at the lower end of this stability range, at conditions akin to diagenesis. Raman spectra indicate that the stilpnomelane, jarosite, and Ca-sulfates are hydrated. The stilpnomelane contains Cl- and was followed by jarosite, a product of acid alteration, and the deposition of Ca-sulfates and halide salts from more neutral chloride solutions.

  19. Quantitative elemental imaging of octopus stylets using PIXE and the nuclear microprobe

    NASA Astrophysics Data System (ADS)

    Doubleday, Zoë; Belton, David; Pecl, Gretta; Semmens, Jayson

    2008-01-01

    By utilising targeted microprobe technology, the analysis of elements incorporated within the hard bio-mineralised structures of marine organisms has provided unique insights into the population biology of many species. As hard structures grow, elements from surrounding waters are incorporated effectively providing a natural 'tag' that is often unique to the animal's particular location or habitat. The spatial distribution of elements within octopus stylets was investigated, using the nuclear microprobe, to assess their potential for determining dispersal and population structure in octopus populations. Proton Induced X-ray Emission (PIXE) was conducted using the Dynamic Analysis method and GeoPIXE software package, which produced high resolution, quantitative elemental maps of whole stylet cross-sections. Ten elements were detected within the stylets which were heterogeneously distributed throughout the microstructure. Although Ca decreased towards the section edge, this trend was consistent between individuals and remained homogeneous in the inner region of the stylet, and thus appears a suitable internal standard for future microprobe analyses. Additional analyses used to investigate the general composition of the stylet structure suggested that they are amorphous and largely organic, however, there was some evidence of phosphatic mineralisation. In conclusion, this study indicates that stylets are suitable for targeted elemental analysis, although this is currently limited to the inner hatch region of the microstructure.

  20. Multielement geochemical investigations by SRXRF microprobe studies on tectite material: Evidence from the NE-Mexican Cretaceous/Tertiary record

    NASA Astrophysics Data System (ADS)

    Harting, M.; Rickers, K.; Kramar, U.; Simon, R.; Staub, S.; Schulte, P.

    2002-12-01

    The K/T boundary is long known as one of a few mass extinctions in earth history. The impact of a big meteorite at the Chicxulub on the northern Yucatan peninsula in Mexico is discussed to have triggered the faunal mass extinction and the rapid change of the palaeoenvironmental conditions near the K/T boundary. Tectite material, especially spherules are explained from many of the sections in correlation to the K/T-boundary event. This rare, glassy or alterated material is extremely variable in its major element chemistry, morphology and stratigraphic position in K/T transitions worldwide. For the first time, we perfom trace element analysis on tectites from the K/T boundary using synchrotron radiation XRF (SRXRF). Measurements were performed at the Hamburger Strahlungssynchrotronlabor HASYLAB at DESY (Hamburg, Germany) and at the ANKA (Karlsruhe, Germany) with polychromatic and monochromatic excitation, respectively collimating the beam to 15 æm by capillary optics. Based on results from SRXRF microprobe determinations, these structures are to be interpreted as mixing of several melts with different chemical composition. The different components may represent melts from different sediment layers and possibly of basement material excavated by the Chicxulub impact. Igneous rocks with andesitic composition in cores at Chicxulub are considered to be impact melt rocks and are correlated mainly by the composition of major elements with the glass spherules found in the surrounding. Our investigations show that it is possible to trace elements with high sensitivity and a high spatial resolution. Some of the samples show clearly zonation and alteration parts, as well as carbonate inclusions, triggered by the Chicxulub impact event. In general, the results from the SRXRF show that the tectite material have different trace element patterns, formed by mixing of melts with different chemical composition derived from different sediment layers and possibly of basement material

  1. The second Mars microprobe is unloaded

    NASA Technical Reports Server (NTRS)

    1998-01-01

    In the Spacecraft Assembly and Encapsulation Facility -2 (SAEF- 2), Chris Voorhees (left) and Satish Krishnan (right), from the Jet Propulsion Laboratory, remove the second Mars microprobe from a drum. Two microprobes will hitchhike on the Mars Polar Lander, scheduled to be launched Jan. 3, 1999, aboard a Delta II rocket. The solar-powered spacecraft is designed to touch down on the Martian surface near the northern-most boundary of the south pole in order to study the water cycle there. The lander also will help scientists learn more about climate change and current resources on Mars, studying such things as frost, dust, water vapor and condensates in the Martian atmosphere. The Mars microprobes, called Deep Space 2, are part of NASA's New Millennium Program. They will complement the climate-related scientific focus of the lander by demonstrating an advanced, rugged microlaser system for detecting subsurface water. Such data on polar subsurface water, in the form of ice, should help put limits on scientific projections for the global abundance of water on Mars.

  2. Electron microprobe mineral analysis guide

    NASA Technical Reports Server (NTRS)

    Brown, R. W.

    1980-01-01

    Electron microprobe mineral analysis guide is a compilation of X-ray tables and spectra recorded from various mineral matrices. Spectra were obtained using electron microprobe, equipped with LiF geared, curved crystal X-ray spectrometers, utilizing typical analytical operating conditions: 15 Kv acceleration potential, 0.02 microampere sample current as measured on a clinopyroxene standard (CP19). Tables and spectra are presented for the majority of elements, fluorine through uranium, occurring in mineral samples from lunar, meteoritic and terrestrial sources. Tables for each element contain relevant analytical information, i.e., analyzing crystal, X-ray peak, background and relative intensity information, X-ray interferences and a section containing notes on the measurement. Originally intended to cover silicates and oxide minerals the tables and spectra have been expanded to cover other mineral phases. Electron microprobe mineral analysis guide is intended as a spectral base to which additional spectra can be added as the analyst encounters new mineral matrices.

  3. Electron microprobe analysis of cryolite

    NASA Astrophysics Data System (ADS)

    Guimarães, F.; Bravo Silva, P.; Ferreira, J.; Piedade, A. P.; Vieira, M. T. F.

    2014-03-01

    A sample of cryolite was studied with a JEOL JXA 8500-F electron microprobe under several operating conditions. A TAP crystal was used to analyse Na and Al and a LDE1 crystal to analyse F. As F and Na are both highly "volatile" elements, special care must be taken during analysis. The measurement order of Na, F and Al is not irrelevant and optimum conditions may also result in different combinations of accelerating voltage, beam current, beam size or counting times. Relevant X-ray signals were recorded in order to investigate the behaviour of the Na Ka and F Ka counts with elapsed time. The incident beam current was also recorded at the same time. In a clear contrast to what has normally been reported in the EPMA analysis of aluminosilicates and silicate glasses, we found that the Na X-ray counts increase with time. This increment of X-rays intensities for sodium in cryolite depends on the operating conditions and is accompanied by a strong migration of fluorine from the beam excitation volume, leading to a decrease in F X-ray counting rates. It was also observed that higher incident beam currents induce higher radiation damage in the mineral. The current instability is consistent with possible electron induced dissociation in the cryolite structure. An analytical protocol was achieved for 6 kV and 15kV accelerating voltage for the correct EPMA analysis of cryolite.

  4. Microprobe PIXE analysis of aluminium in the brains of patients with Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Horino, Y.; Mokuno, Y.; Kakimi, S.; Fujii, K.

    1996-04-01

    To investigate the cause of Alzheimer's disease (senile dementia), we examined aluminium (Al) in the rat liver, and in the brains (hippocampus) of Alzheimer's disease patients using heavy ion (5 MeV Si 3+) microprobe and proton (2 MeV) microprobe PIXE analysis. Heavy ion microprobes (3 MeV Si 2+) have several time's higher sensitivity for Al detection than 2 MeV proton microprobes. (1) In the rat liver, Al was detected in the cell nuclei, where phosphorus (P) was most densely distributed. (2) We also demonstrated Al in the cell nuclei isolated from Alzheimer's disease brains using heavy ion (5 MeV Si 3+) microprobes. Al spectra were detected using 2 MeV proton microprobes in the isolated brain cell nuclei. Al could not be observed in areas where P was present in relatively small amounts, or was absent. Our results indicate that Alzheimer's disease is caused by irreversible accumulation of Al in the nuclei of brain cells.

  5. Theoretical and experimental study of 15N NMR protonation shifts.

    PubMed

    Semenov, Valentin A; Samultsev, Dmitry O; Krivdin, Leonid B

    2015-06-01

    A combined theoretical and experimental study revealed that the nature of the upfield (shielding) protonation effect in 15N NMR originates in the change of the contribution of the sp(2)-hybridized nitrogen lone pair on protonation resulting in a marked shielding of nitrogen of about 100 ppm. On the contrary, for amine-type nitrogen, protonation of the nitrogen lone pair results in the deshielding protonation effect of about 25 ppm, so that the total deshielding protonation effect of about 10 ppm is due to the interplay of the contributions of adjacent natural bond orbitals. A versatile computational scheme for the calculation of 15N NMR chemical shifts of protonated nitrogen species and their neutral precursors is proposed at the density functional theory level taking into account solvent effects within the supermolecule solvation model. PMID:25891386

  6. Study on patient-induced radioactivity during proton treatment in hengjian proton medical facility.

    PubMed

    Wu, Qingbiao; Wang, Qingbin; Liang, Tianjiao; Zhang, Gang; Ma, Yinglin; Chen, Yu; Ye, Rong; Liu, Qiongyao; Wang, Yufei; Wang, Huaibao

    2016-09-01

    At present, increasingly more proton medical facilities have been established globally for better curative effect and less side effect in tumor treatment. Compared with electron and photon, proton delivers more energy and dose at its end of range (Bragg peak), and has less lateral scattering for its much larger mass. However, proton is much easier to produce neutron and induced radioactivity, which makes radiation protection for proton accelerators more difficult than for electron accelerators. This study focuses on the problem of patient-induced radioactivity during proton treatment, which has been ignored for years. However, we confirmed it is a vital factor for radiation protection to both patient escort and positioning technician, by FLUKA's simulation and activation formula calculation of Hengjian Proton Medical Facility (HJPMF), whose energy ranges from 130 to 230MeV. Furthermore, new formulas for calculating the activity buildup process of periodic irradiation were derived and used to study the relationship between saturation degree and half-life of nuclides. Finally, suggestions are put forward to lessen the radiation hazard from patient-induced radioactivity. PMID:27423927

  7. Proton Conductivity Studies on Biopolymer Electrolytes

    SciTech Connect

    Harun, N. I.; Sabri, N. S.; Rosli, N. H. A.; Taib, M. F. M.; Saaid, S. I. Y.; Kudin, T. I. T.; Ali, A. M. M.; Yahya, M. Z. A.

    2010-07-07

    Proton conducting solid biopolymer electrolyte membranes consisting of methyl cellulose (MC) and different wt.% of ammonium nitrate (NH{sub 4}NO{sub 3}) were prepared by solution cast technique. Impedance spectroscopy was carried out to study electrical characteristics of bulk materials. The ionic conductivity of the prepared samples was calculated using the bulk resistance (R{sub b}) obtained from impedance spectroscopy plot. The highest ionic conductivity obtained was 1.17x10{sup -4} Scm{sup -1} for the sample with composition ratio of MC(50): NH{sub 4}NO{sub 3}(50). To enhance the ionic conductivity, propylene carbonate (PC) and ethylene carbonate (EC) plasticizers were introduced. It was found that the ionic conductivity of polymer electrolyte membranes increased with the increase in plasticizers concentration. The ionic conductivities of solid polymer electrolytes based on MC-NH{sub 4}NO{sub 3}-PC was enhanced up to 4.91x10{sup -3} Scm{sup -1} while for the MC-NH{sub 4}NO{sub 3}-EC system, the highest conductivity was 1.74x10{sup -2} Scm{sup -1}. The addition of more plasticizer however decreases in mechanical stability of the membranes.

  8. Feasibility study of proton-based quality assurance of proton range compensator

    NASA Astrophysics Data System (ADS)

    Park, S.; Jeong, C.; Min, B. J.; Kwak, J.; Lee, J.; Cho, S.; Shin, D.; Lim, Y. K.; Park, S. Y.; Lee, S. B.

    2013-06-01

    All patient specific range compensators (RCs) are customized for achieving distal dose conformity of target volume in passively scattered proton therapy. Compensators are milled precisely using a computerized machine. In proton therapy, precision of the compensator is critical and quality assurance (QA) is required to protect normal tissues and organs from radiation damage. This study aims to evaluate the precision of proton-based quality assurance of range compensator. First, the geometry information of two compensators was extracted from the DICOM Radiotherapy (RT) plan. Next, RCs were irradiated on the EBT film individually by proton beam which is modulated to have a photon-like percent depth dose (PDD). Step phantoms were also irradiated on the EBT film to generate calibration curve which indicates relationship between optical density of irradiated film and perpendicular depth of compensator. Comparisons were made using the mean absolute difference (MAD) between coordinate information from DICOM RT and converted depth information from the EBT film. MAD over the whole region was 1.7, and 2.0 mm. However, MAD over the relatively flat regions on each compensator selected for comparison was within 1 mm. These results shows that proton-based quality assurance of range compensator is feasible and it is expected to achieve MAD over the whole region less than 1 mm with further correction about scattering effect of proton imaging.

  9. Decay Studies of Proton Emitter: 151Lu

    NASA Astrophysics Data System (ADS)

    Wang, F.; Sun, B.; Zhu, L.; Liu, Z.

    An experiment aiming to search for new isomers in the region of proton emitter 151Lu was done in the Accelerator Laboratory of the University of Jyväskylä (JYFL). Rich information on 151Lu and 151mLu has been obtained from our data analysis. In this work, we revisit the level scheme of 151Lu by using the proton-tagging technique and measure the half-lives of 151Lu and 151mLu are 82.8±0.7 ms and 15.4±0.8 μs, respectively.

  10. Frontal IBICC study of the induced proton radiation damage in CdTe detectors

    NASA Astrophysics Data System (ADS)

    Pastuović, Željko; Jakšić, Milko

    2001-07-01

    Within a continuous international effort in developing the non-cryogenic semiconductor detectors for gamma ray spectroscopy, various wide gap materials were considered. With a best performance achieved, CdTe- and CdZnTe-based detectors become today widely accepted and commercially available. In addition to possible future use of such detectors for particle-induced gamma-ray emission (PIGE), nuclear microprobes are in recent years applied more as their characterisation tool using the ion beam-induced charge collection (IBICC) technique. Several CdTe detectors of 2×2×1 mm3 size were used in this study. On the basis of frontal IBICC measurements of the charge collection efficiency (CCE) distribution, the spectroscopy performance of detectors were measured. Further degradation of charge collection efficiency and the downward trend in peak position were studied by on-line irradiation of CdTe samples with 3 MeV protons up to 10 10 p/cm2 radiation dose.

  11. Moessbauer and Electron Microprobe Studies of Density Separates of Martian Nakhlite Mil03346: Implications for Interpretation of Moessbauer Spectra Acquired by the Mars Exploration Rovers

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; McKay, G. A.; Agresti, D. G.; Li, Loan

    2008-01-01

    Martian meteorite MIL03346 is described as an augite-rich cumulate rock with approx.80%, approx.3%, and approx.21% modal phase proportions of augite (CPX), olivine and glassy mesostasis, respectively, and is classified as a nakhlite [1]. The Mossbauer spectrum for whole rock (WR) MIL 03346 is unusual for Martian meteorites in that it has a distinct magnetite subspectrum (7% subspectral area) [2]. The meteorite also has products of pre-terrestrial aqueous alteration ("iddingsite") that is associated primarily with the basaltic glass and olivine. The Mossbauer spectrometers on the Mars Exploration Rovers have measured the Fe oxidation state and the Fe mineralogical composition of rocks and soils on the planet s surface since their landing in Gusev Crater and Meridiani Planum in January, 2004 [3,4]. The MIL 03346 meteorite provides an opportunity to "ground truth" or refine Fe phase identifications. This is particularly the case for the so-called "nanophase ferric oxide" (npOx) component. NpOx is a generic name for a ferric rich product of oxidative alteration. On Earth, where we can take samples apart and study individual phases, examples of npOx include ferrihydrite, schwertmannite, akagaaneite, and superparamagnetic (small particle) goethite and hematite. It is also possible for ferric iron to be associated to some unknown extent with igneous phases like pyroxene. We report here an electron microprobe (EMPA) and Moessbauer (MB) study of density separates of MIL 03346. The same separates were used for isotopic studies by [5]. Experimental techniques are described by [6,7].

  12. An x-ray microprobe beam line for trace element analysis

    SciTech Connect

    Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kwiatek, W.M.; Long, G.J.; Pounds, J.G.; Schidlovsky, G.; Spanne, P.; Rivers, M.L.; Sutton, S.R.

    1987-01-01

    The application of synchrotron radiation to an x-ray microprobe for trace element analysis is a complementary and natural extension of existing microprobe techniques using electrons, protons, and heavier ions as excitation sources for x-ray fluorescence. The ability to focus charged particles leads to electron microprobes with spatial resolutions in the sub-micrometer range and down to 100 ppM detection limits and proton microprobes with micrometer resolution and ppM detection limits. The characteristics of synchrotron radiation that prove useful for microprobe analysis include a broad and continuous energy spectrum, a relatively small amount of radiation damage compared to that deposited by charged particles, a highly polarized source which reduces background scattered radiation in an appropriate counting geometry, and a small vertical divergence angle of approx.0.2 mrad which allows for focussing of the light beam into a small spot with high flux. The features of a dedicated x-ray microprobe beam line developed at the National Synchrotron Light Source (NSLS) are described. 4 refs., 3 figs.

  13. Microprobe analysis of brine shrimp grown on meteorite extracts

    NASA Astrophysics Data System (ADS)

    Kennedy, J.; Mautner, M. N.; Barry, B.; Markwitz, A.

    2007-07-01

    Nuclear microprobe methods have been used to investigate the uptake and distribution of various elements by brine shrimps and their unhatched eggs when grown in extracts of the Murchison and Allende carbonaceous meteorites, which were selected as model space resources. Measurements were carried out using a focussed 2 MeV proton beam raster scanned over the samples in order to obtain the average elemental concentrations. Line scans across the egg and shrimp samples show uptake of elements such as Mg, Ni, S and P which are present in the meteorites. The results confirmed that carbonaceous chondrite materials can provide nutrients, including high levels of the essential nutrient phosphate. The concentrations of these elements varied significantly between shrimp and eggs grown in extracts of the two meteorite types, which can help in identifying optimal growth media. Our results illustrate that nuclear microprobe techniques can determine elemental concentrations in organisms exposed to meteorite derived media and thus help in identifying useful future resources.

  14. Nuclear micro-probe analysis of Arabidopsis thaliana leaves

    NASA Astrophysics Data System (ADS)

    Ager, F. J.; Ynsa, M. D.; Domínguez-Solís, J. R.; López-Martín, M. C.; Gotor, C.; Romero, L. C.

    2003-09-01

    Phytoremediation is a cost-effective plant-based approach for remediation of soils and waters which takes advantage of the remarkable ability of some plants to concentrate elements and compounds from the environment and to metabolize various molecules in their tissues, such as toxic heavy metals and organic pollutants. Nowadays, phytoremediation technology is becoming of paramount importance when environmental decontamination is concerned, due to the emerging knowledge of its physiological and molecular mechanisms and the new biological and engineering strategies designed to optimize and improve it. In addition, the feasibility of using plants for environmental cleanup has been confirmed by many different trials around the world. Arabidopsis thaliana plants can be used for basic studies to improve the technology on phytoremediation. Making use of nuclear microscopy techniques, in this paper we study leaves of wild type and transgenic A. thaliana plants grown in a cadmium-rich environment under different conditions. Micro-PIXE, RBS and SEM analyses, performed on the scanning proton micro-probe at the CNA in Seville (Spain), prove that cadmium is preferentially sequestered in the central region of epidermal trichome and allow comparing the effects of genetic modifications.

  15. A wireless beta-microprobe based on pixelated silicon for in vivo brain studies in freely moving rats

    NASA Astrophysics Data System (ADS)

    Märk, J.; Benoit, D.; Balasse, L.; Benoit, M.; Clémens, J. C.; Fieux, S.; Fougeron, D.; Graber-Bolis, J.; Janvier, B.; Jevaud, M.; Genoux, A.; Gisquet-Verrier, P.; Menouni, M.; Pain, F.; Pinot, L.; Tourvielle, C.; Zimmer, L.; Morel, C.; Laniece, P.

    2013-07-01

    The investigation of neurophysiological mechanisms underlying the functional specificity of brain regions requires the development of technologies that are well adjusted to in vivo studies in small animals. An exciting challenge remains the combination of brain imaging and behavioural studies, which associates molecular processes of neuronal communications to their related actions. A pixelated intracerebral probe (PIXSIC) presents a novel strategy using a submillimetric probe for beta+ radiotracer detection based on a pixelated silicon diode that can be stereotaxically implanted in the brain region of interest. This fully autonomous detection system permits time-resolved high sensitivity measurements of radiotracers with additional imaging features in freely moving rats. An application-specific integrated circuit (ASIC) allows for parallel signal processing of each pixel and enables the wireless operation. All components of the detector were tested and characterized. The beta+ sensitivity of the system was determined with the probe dipped into radiotracer solutions. Monte Carlo simulations served to validate the experimental values and assess the contribution of gamma noise. Preliminary implantation tests on anaesthetized rats proved PIXSIC's functionality in brain tissue. High spatial resolution allows for the visualization of radiotracer concentration in different brain regions with high temporal resolution.

  16. Studies of Unstable Nuclei with Spin-Polarized Proton Target

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Satoshi; Uesaka, Tomohiro; Wakui, Takashi; Chebotaryov, Sergey; Kawahara, Tomomi; Kawase, Shoichiro; Milman, Evgeniy; Tang, Tsz Leung; Tateishi, Kenichiro; Teranishi, Takashi

    2016-02-01

    Roles of spin-dependent interactions in unstable nuclei have been investigated via the direct reaction of radioactive ions with a solid spin-polarized proton target. The target has a unique advantage of a high polarization of 20-30% under low magnetic field of 0.1 T and at a high temperature of 100 K, which allow us to detect recoil protons with good angular resolution. Present status of on-going experimental studies at intermediate energies, such as proton elastic scattering and (p, 2p) knockout reaction, and new physics opportunities expected with low-energy RI beams are overviewed.

  17. The first Mars microprobe is unloaded

    NASA Technical Reports Server (NTRS)

    1998-01-01

    In the Spacecraft Assembly and Encapsulation Facility -2 (SAEF- 2), workers from the Jet Propulsion Laboratory open the drums containing the Mars microprobes that will hitchhike on the Mars Polar Lander. From left, they are Satish Krishnan, Charles Cruzan, Chris Voorhees and Arden Acord. Scheduled to be launched Jan. 3, 1999, aboard a Delta II rocket, the solar-powered spacecraft is designed to touch down on the Martian surface near the northern-most boundary of the south pole in order to study the water cycle there. The lander also will help scientists learn more about climate change and current resources on Mars, studying such things as frost, dust, water vapor and condensates in the Martian atmosphere. The Mars microprobes, called Deep Space 2, are part of NASA's New Millennium Program. They will complement the climate-related scientific focus of the lander by demonstrating an advanced, rugged microlaser system for detecting subsurface water. Such data on polar subsurface water, in the form of ice, should help put limits on scientific projections for the global abundance of water on Mars.

  18. The Fudan nuclear microprobe set-up and performance

    NASA Astrophysics Data System (ADS)

    Zhong, L.; Zhuang, W.; Shen, H.; Mi, Y.; Wu, Y.; Liu, B.; Yang, M.; Cheng, H.

    2007-07-01

    A new scanning nuclear microprobe has been constructed at the Institute of Modern Physics in Fudan University, to replace the old microbeam system which had been running for more than ten years. The key parts were purchased from Oxford Microbeams Ltd., including triplet quadrupole lens (model OM-150), collimator slits, scanning system, target chamber, and data acquisition system. Ion beams are provided from a NEC 9SDH-2 Tandem accelerator. Three CCD cameras and multiple monitors were installed to assist beam adjust. The design of beam line and beam monitors is described. Beam optics calculations were carried out based on the specific Fudan microprobe system geometry, and the results regarding beam line performance and limitations of the spacial resolution are presented and discussed here. A comparison with experimental results is given as well. About 1.5 μm beam spot size could be achieved with a 3 MeV proton beam at a current of around 10 pA. Recently, the new microprobe is applied to obtain information of fly ash particle, algae cell and otoliths.

  19. Long-term clinical evaluation of endodontically treated teeth by 15 F CO2 laser microprobe: three years clinical follow-up of 1512 root canals--in-vivo study

    NASA Astrophysics Data System (ADS)

    Kesler, Gavriel; Koren, Rumelia; Kesler, Anat; Hay, Nissim; Gal, Rivka

    1999-05-01

    The purpose of this study was to determine the efficiency of 15 F CO2 laser microprobe, in cases of periapical lesions, by eliminating the pathological reaction caused by certain species of bacteria, reduction of reinfection and stimulation of osteogenesis in the periapical region. Until now, no suitable delivery fiber existed for CO2 laser endodontic radiation in the apical region where it is most difficult to eliminate the pulp tissue using conventional methods. To overcome this problem, Sharplan laser designed a microprobe that reaches closer to the apex, distributing the energy density to a smaller area of the root canal, thus favorably increasing the thermal effects. The study was conducted on 900 teeth, divided in two groups. 468 were new case, carefully selected according to strict parameters such as: wide periapical translucency over 1mm, supported by digital x-ray, with a lesion of 3mm and more. All root canals were mechanically prepared in the conventional method up to size 35, Physiological saline solution served as finding solution and were treated by 15 F CO2 laser microprobe for 60 pulses repeatedly. The temperature at the surrounding tissue of the root did not exceed 38 degrees C filling of the canal was possible at the same appointment, without antibiotical treatment. 432 of the cases, which were referred to us by other dentists, after an unsuccessful treatment according to the classical therapy, were treated by the same laser therapy. Follow up was performed by clinical examination, and digital x-ray taken, during and after treatment as well as after 3, 6, 9, 12 month. The result demonstrate 98% success rate in both study groups, according to objective criteria for a successful treatment such as: reduction of apical translucency after 2- 6 months, freedom form clinical complains, and no need for periapical surgery.

  20. Ion microprobe studies of trace elements in Apollo 14 volcanic glass beads - Comparisons to Apollo 14 mare basalts and petrogenesis of picritic magmas

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; Papike, J. J.; Simon, S. B.; Shimizu, N.; Yurimoto, H.

    1990-01-01

    Results are presented from trace element analysis, by ion microprobe techniques, of individual glass beads representing seven compositionally distinct types of picritic glass beads from the Apollo 14 landing site. The picritic glass beads at the A-14 exhibited a wide range of primary magma compositions and a lack of petrogenetic linkage (via crystal fractionation) to crystalline basalts. The wide range of major and trace element characteristics of the picritic glass beads is consistent with derivation from mineralogically distinct sources which consist of varying proportions of olivine + orthopyroxene +/- clonopyroxene +/- ilmenite +/- plagioclase +/- KREEP component.

  1. Heavy-ion broad-beam and microprobe studies of single-event upsets in 0.20 um SiGe heterojunction bipolar transistors and circuits.

    SciTech Connect

    Fritz, Karl; Irwin, Timothy J.; Niu, Guofu; Fodness, Bryan; Carts, Martin A.; Marshall, Paul W.; Reed, Robert A.; Gilbert, Barry; Randall, Barbara; Prairie, Jason; Riggs, Pam; Pickel, James C.; LaBel, Kenneth; Cressler, John D.; Krithivasan, Ramkumar; Dodd, Paul Emerson; Vizkelethy, Gyorgy

    2003-09-01

    Combining broad-beam circuit level single-event upset (SEU) response with heavy ion microprobe charge collection measurements on single silicon-germanium heterojunction bipolar transistors improves understanding of the charge collection mechanisms responsible for SEU response of digital SiGe HBT technology. This new understanding of the SEU mechanisms shows that the right rectangular parallele-piped model for the sensitive volume is not applicable to this technology. A new first-order physical model is proposed and calibrated with moderate success.

  2. Progress in Fast Ignition Studies with Electrons and Protons

    SciTech Connect

    MacKinnon, A. J.; Chen, H.; Hey, D.; Key, M. H.; MacPhee, A. G.; Patel, P. K.; Ping, Y.; Akli, K. U.; Stephens, R. B.; Bartal, T.; Beg, F. N.; Chawla, S.; Chen, S.; Higginson, D.; King, J. A.; Ma, T.; Wei, M. S.; Chen, C. D.; Chowdhury, E.; Link, A.

    2009-09-10

    Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) concept for initiating burn in a fusion capsule. In order to investigate critical aspects needed for a FI point design, experiments were performed to study 1) laser-to-electrons or protons conversion issues and 2) laser-cone interactions including prepulse effects. A large suite of diagnostics was utilized to study these important parameters. Using cone--wire surrogate targets it is found that pre-pulse levels on medium scale lasers such as Titan at Lawrence Livermore National Laboratory produce long scale length plasmas that strongly effect coupling of the laser to FI relevant electrons inside cones. The cone wall thickness also affects coupling to the wire. Conversion efficiency to protons has also been measured and modeled as a function of target thickness, material. Conclusions from the proton and electron source experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed. In conclusion, a program of study will be presented based on understanding the fundamental physics of the electron or proton source relevant to FI.

  3. 200 MeV Proton Radiography Studies with a Hand Phantom Using a Prototype Proton CT Scanner

    PubMed Central

    Plautz, Tia; Bashkirov, V.; Feng, V.; Hurley, F.; Johnson, R.P.; Leary, C.; Macafee, S.; Plumb, A.; Rykalin, V.; Sadrozinski, H.F.-W.; Schubert, K.; Schulte, R.; Schultze, B.; Steinberg, D.; Witt, M.; Zatserklyaniy, A.

    2014-01-01

    Proton radiography has applications in patient alignment and verification procedures for proton beam radiation therapy. In this paper, we report an experiment which used 200 MeV protons to generate proton energy-loss and scattering radiographs of a hand phantom. The experiment used the first-generation proton CT scanner prototype, which was installed on the research beam line of the clinical proton synchrotron at Loma Linda University Medical Center (LLUMC). It was found that while both radiographs displayed anatomical details of the hand phantom, the energy-loss radiograph had a noticeably higher resolution. Nonetheless, scattering radiography may yield more contrast between soft and bone tissue than energy-loss radiography, however, this requires further study. This study contributes to the optimization of the performance of the next-generation of clinical proton CT scanners. Furthermore, it demonstrates the potential of proton imaging (proton radiography and CT), which is now within reach of becoming available as a new, potentially low-dose medical imaging modality. PMID:24710156

  4. 200 MeV proton radiography studies with a hand phantom using a prototype proton CT scanner.

    PubMed

    Plautz, Tia; Bashkirov, V; Feng, V; Hurley, F; Johnson, R P; Leary, C; Macafee, S; Plumb, A; Rykalin, V; Sadrozinski, H F-W; Schubert, K; Schulte, R; Schultze, B; Steinberg, D; Witt, M; Zatserklyaniy, A

    2014-04-01

    Proton radiography has applications in patient alignment and verification procedures for proton beam radiation therapy. In this paper, we report an experiment which used 200 MeV protons to generate proton energy-loss and scattering radiographs of a hand phantom. The experiment used the first-generation proton computed tomography (CT) scanner prototype, which was installed on the research beam line of the clinical proton synchrotron at Loma Linda University Medical Center. It was found that while both radiographs displayed anatomical details of the hand phantom, the energy-loss radiograph had a noticeably higher resolution. Nonetheless, scattering radiography may yield more contrast between soft and bone tissue than energy-loss radiography, however, this requires further study. This study contributes to the optimization of the performance of the next-generation of clinical proton CT scanners. Furthermore, it demonstrates the potential of proton imaging (proton radiography and CT), which is now within reach of becoming available as a new, potentially low-dose medical imaging modality. PMID:24710156

  5. Protonated Forms of Monoclinic Zirconia: A Theoretical Study

    SciTech Connect

    Mantz, Yves A.; Gemmen, Randall S.

    2010-05-06

    In various materials applications of zirconia, protonated forms of monoclinic zirconia may be formed, motivating their study within the framework of density-functional theory. Using the HCTH/120 exchange-correlation functional, the equations of state of yttria and of the three low-pressure zirconia polymorphs are computed, to verify our approach. Next, the favored charge state of a hydrogen atom in monoclinic zirconia is shown to be positive for all Fermilevel energies in the band gap, by the computation of defect formation energies.This result is consistent with a single previous theoretical prediction at midgap as well as muonium spectroscopy experiments. For the formally positively (+1e) charged system of a proton in monoclinic zirconia (with a homogeneous neutralizing background charge densityimplicitly included), modeled using up to a 3 x 3 x 3 arrangement of unit cells, different stable and metastable structures are identified. They are similar to those structures previously proposed for the neutral system of hydrogen-doedmonoclinic zirconia, at a similar level of theory. As predicted using the HCTH/120 functional, the lowest energy structure of the proton bonded to one of the two available oxygen atom types, O1, is favored by 0.39 eV compared to that of the proton bonded to O2. The rate of proton transfer between O1 ions is slower than that for hydrogen-dopedmonoclinic zirconia, whose transition-state structures may be lowered in energy by the extra electron.

  6. Studies of electron and proton isochoric heating for fast ignition

    SciTech Connect

    Mackinnon, A; Key, M; Akli, K; Beg, F; Clarke, R; Clarke, D; Chen, M; Chung, H; Chen, S; Freeman, R; Green, J; Gu, P; Gregori, G; Highbarger, K; Habara, H; Hatchett, S; Hey, D; Heathcote, R; Hill, J; King, J; Kodama, R; Koch, J; Lancaster, K; Langdon, B; Murphy, C; Norreys, P; Neely, D; Nakatsutsumi, M; Nakamura, H; Patel, N; Patel, P; Pasley, J; Snavley, R; Stephens, R; Stoeckl, C; Foord, M; Tabak, M; Theobald, W; Storm, M; Tanaka, K; Tempo, M; Toley, M; Town, R; Wilks, S; VanWoerkom, L; Weber, R; Yabuuchi, T; Zhang, B

    2006-10-02

    Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) proposal to use this technique to initiate burn in a fusion capsule. Experiments designed to investigate electron isochoric heating have measured heating in two limiting cases of interest to fast ignition, small planar foils and hollow cones. Data from Cu K{alpha} fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68eV and 256 eV are used to test PIC and Hybrid PIC modeling of the interaction. Isochoric heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a cone have been studied with the same diagnostic methods plus imaging of proton induced K{alpha}. Conversion efficiency to protons has also been measured and modeled. Conclusions from the proton and electron heating experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed.

  7. Microprobe analysis of chlorpromazine pigmentation

    SciTech Connect

    Benning, T.L.; McCormack, K.M.; Ingram, P.; Kaplan, D.L.; Shelburne, J.D.

    1988-10-01

    We describe the histochemical, ultrastructural, and microanalytical features of a skin biopsy specimen obtained from a patient with chlorpromazine pigmentation. Golden-brown pigment granules were present in the dermis, predominantly in a perivascular arrangement. The granules stained positively with the Fontana-Masson stain for silver-reducing substances and negatively with Perl's stain for iron. Electron microscopy revealed dense inclusion bodies in dermal histiocytes, pericytes, endothelial cells, and Schwann cells, as well as lying free in the extracellular matrix. These ''chlorpromazine bodies'' were quite dense even in unosmicated, unstained ultrathin sections, indicating that the pigmentation is related, at least in part, to the inclusions. Microprobe analysis of the chlorpromazine bodies revealed a striking peak for sulfur, which strongly suggests the presence of the drug or its metabolite within these inclusions.

  8. Ion microprobe study of Au and Carlin-type trace metals in rhyolite melt inclusions from Eocene dikes and ash-flow tuff in northern Nevada

    NASA Astrophysics Data System (ADS)

    Watts, K. E.; Colgan, J. P.; John, D. A.; Henry, C.; Coble, M. A.; Hervig, R. L.

    2013-12-01

    , Te, As) were within 'typical' ranges for rhyolites, and with the possible exception of As, cannot be used to differentiate the Caetano and Cortez melt inclusion datasets. Synthesis of SIMS trace element concentrations with major element data obtained by electron microprobe does not reveal any consistent trends of trace element enrichments or depletions in the analyzed inclusions. This study highlights the utility of SIMS for quantifying low-level concentrations of Au and other trace metals at the small spatial scales (10s of microns) required for melt inclusion work. Our results do not provide evidence for a magmatic origin of Au in Carlin-type gold deposits, or at least not as retained in the melt inclusion record of the Eocene rhyolites in this study.

  9. Short-lived proton radioactivity studies at HRIBF

    SciTech Connect

    Batchelder, J. C.; Bingham, C. R.; Ginter, T. N.; Gross, C. J.; Grzywacz, R.; Karny, M.; Janas, Z.; Mas, F.; McConnell, J. W.; Rykaczewski, K.; Toth, K. S.; Piechaczek, A.; Zganjar, E. F.; Semmes, P.

    1999-11-16

    An accurate determination of the experimental spectroscopic factor of proton emitting nuclei precisely defines the main component of the proton wave function for the unbound state. However, this has proven difficult for nuclei with Z{<=}71 due to the unknown beta-branching ratios involved. One way to solve this problem is to study proton-emitters with half-lives far too short for beta-emission to compete. Recent work at the Holifield Radioactive Ion Beam Facility has produced information on {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu, all of which have half-lives in the {mu}s region. A comparison between calculated and experimental spectroscopic factors for these nuclei is given.

  10. Comments on Injector Proton Beam Study in Run 2014

    SciTech Connect

    Zhang, S. Y.

    2014-09-15

    During the entire period of injector proton study in run 2014, it seems that the beam transverse emittance out of Booster is larger than that in run 2013. The emittance measured at the BtA transfer line and also the transmission from Booster late to AGS late are presented for this argument. In addition to this problem, it seems that the multiturn Booster injection, which defines the transverse emittance, needs more attention. Moreover, for high intensity operations, the space charge effect may be already relevant in RHIC polarized proton runs. With the RHIC proton intensity improvement in the next several years, higher Booster input intensity is needed, therefore, the space charge effect at the Booster injection and early ramp may become a new limiting factor.

  11. Progress of the Proton-Ion Medical Machine Study (PIMMS).

    PubMed

    Bryant, P J

    1999-06-01

    The Proton-Ion Medical Machine Study (PIMMS) was set up following an agreement between Professor M. Regler of the Med-AUSTRON (Austria) and Professor U. Amaldi of the TERA Foundation (Italy) to join their efforts in the design of a medical synchrotron that could later be adapted to individual national needs. CERN agreed to host this study inside its PS Division and to contribute one full-time member to the study team. The study group has worked in collaboration with GSI (Germany) and was more recently joined by Onkologie 2000 (Czech Republic). Work started in January 1996 and is expected to finish during 1998. The agreed aim of the study was to investigate and design a generic facility that would allow the direct clinical comparison of protons and carbon ions for cancer treatment. The accelerator was to be designed primarily for high-precision active beam scanning with both protons and ions, but was also to be capable of delivering proton beams with passive spreading. PMID:10394382

  12. Method study of parameter choice for a circular proton-proton collider

    NASA Astrophysics Data System (ADS)

    Su, Feng; Gao, Jie; Xiao, Ming; Wang, Dou; Wang, Yi-Wei; Bai, Sha; Bian, Tian-Jian

    2016-01-01

    In this paper we show a systematic method of appropriate parameter choice for a circular proton-proton collider by using an analytical expression for the beam-beam tune shift limit, starting from a given design goal and technical limitations. A suitable parameter space has been explored. Based on the parameter scan, sets of appropriate parameters designed for a 50 km and 100 km circular proton-proton collider are proposed. Supported by National Natural Science Foundation of China (11175192)

  13. Lack of effect of microinjection of noradrenaline or medetomidine on stimulus-evoked release of substance P in the spinal cord of the cat: a study with antibody microprobes.

    PubMed Central

    Lang, C. W.; Hope, P. J.; Grubb, B. D.; Duggan, A. W.

    1994-01-01

    1. Experiments were performed on barbiturate anaesthetized, spinalized cats to investigate the effect of microinjected noradrenaline or medetomidine on the release of immunoreactive substance P in the dorsal spinal cord following peripheral nerve stimulation. The presence of immunoreactive substance P was assessed with microprobes bearing C-terminus-directed antibodies to substance P. 2. Noradrenaline or medetomidine were microinjected into the grey matter of the spinal cord, near microprobe insertion sites, at depths of 2.5, 2.0, 1.5 and 1.0 mm below the spinal cord surface with volumes of approximately 0.125 microliters and a concentration of 10(-3) M. 3. In the untreated spinal cord, electrical stimulation of the ipsilateral tibial nerve (suprathreshold for C-fibres) elicited release of immunoreactive substance P which was centred in and around lamina II. Neither noradrenaline nor medetomidine administration in the manner described produced significant alterations in this pattern of nerve stimulus-evoked release. 4. In agreement with recent ultrastructural studies these results do not support a control of substance P release by catecholamines released from sites near to the central terminals of small diameter primary afferent fibres. PMID:7522862

  14. A petrologic and ion microprobe study of a Vigarano Type B refractory inclusion - Evolution by multiple stages of alteration and melting

    NASA Technical Reports Server (NTRS)

    Macpherson, Glenn J.; Davis, Andrew M.

    1993-01-01

    A Type B Ca-, Al-rich 6-m-diam inclusion (CAI) found in the Vigarano C3V chondrite was inspected using optical and scanning electron microscopies and ion microprobe analyses. It was found that the primary constituents of the CAI inclusion are (in percent), melilite (52), fassaite, (20), anorthite (18), spinel (10), and trace Fe-Ni metal. It is noted that, while many of the properties of the inclusion indicate solidification from a melt droplet, the Al-26/Mg-26 isotopic systematics and some textural relationships are incompatible with single-stage closed system crystallization of a homogeneous molten droplet, indicating that the history of this inclusion must have been more complex than melt solidification alone. Moreover, there was unusually high content of Na in melilite, suggesting that the droplet did not form by melting of pristine high-temperature nebular condensates.

  15. Materials analysis with a nuclear microprobe

    SciTech Connect

    Maggiore, C.J.

    1980-01-01

    The ability to produce focused beams of a few MeV light ions from Van de Graaff accelerators has resulted in the development of nuclear microprobes. Rutherford backscattering, nuclear reactions, and particle-induced x-ray emission are used to provide spatially resolved information from the near surface region of materials. Rutherford backscattering provides nondestructive depth and mass resolution. Nuclear reactions are sensitive to light elements (Z < 15). Particle-induced x-ray analysis is similar to electron microprobe analysis, but 2 orders of magnitude more sensitive. The focused beams are usually produced with specially designed multiplets of magnetic quadrupoles. The LASL microprobe uses a superconducting solenoid as a final lens. The data are acquired by a computer interfaced to the experiment with CAMAC. The characteristics of the information acquired with a nuclear microprobe are discussed; the means of producing the beams of nuclear particles are described; and the limitations and applications of such systems are given.

  16. Dynamic studies of proton diffusion in mesoscopic heterogeneous matrix

    PubMed Central

    Gutman, M.; Nachliel, E.; Kiryati, S.

    1992-01-01

    The thin water layer, as found in chloroplast or mitochondria, is confined between low dielectric amphypathic surfaces a few nm apart. The physical properties of this mesoscopic space, and how its dimensions affect the rate of chemical reactions proceeding in it, is the subject for this study. The method selected for this purpose is time resolved fluorometry which can monitor the reversible dissociation of a proton from excited molecule of pyranine (8 hydroxy pyrene 1,3,6 tri sulfonate) trapped in thin water layers of a multilamellar vesicle made of neutral or slightly charged phospholipids. The results were analyzed by a computer program of N. Agmon (Pines, E., D. Huppert, and N. Agmon. 1988. J. Am. Chem. Soc. 88:5620-5630) that simulates the diffusion of a proton, subjected to electrostatic attraction, in a thin water layer enclosed between low affinity, proton binding surfaces. The analysis determines the diffusion coefficient of the proton, the effective dielectric constant of the water and the water accessibility of the phosphomoieties of the lipids. These parameters were measured for various lipids [egg-phosphatidylcholine (egg PC), dipalmitoyl phosphatidylcholine (DPPC), cholesterol + DPPC (1:1) and egg PC plus phosphatidyl serine (9:1)] and under varying osmotic pressure which reduces the width of the water layer down to ∼10 ∼ across. We found that: (a) The effective dielectric constant of the aqueous layer, depending on the lipid composition, is ∼40. (b) The diffusion coefficient of the proton in the thin layer (30-10 ∼ across) is that measured in bulk water D = 9.3 10-5 cm2/s, indicating that the water retains its normal liquid state even on contact with the membrane. (c) The reactivity of the phosphomoiety, quantitated by rate of its reaction with proton, diminishes under lateral pressure which reduces the surface area per lipid. We find no evidence for abnormal dynamics of proton transfer at the lipid water interface which, by any mechanism

  17. Design study of a medical proton linac for neutron therapy

    SciTech Connect

    Machida, S.; Raparia, D.

    1988-08-26

    This paper describes a design study which establishes the physical parameters of the low energy beam transport, radiofrequency quadrupole, and linac, using computer programs available at Fermilab. Beam dynamics studies verify that the desired beam parameters can be achieved. The machine described here meets the aforementioned requirements and can be built using existing technology. Also discussed are other technically feasible options which could be attractive to clinicians, though they would complicate the design of the machine and increase construction costs. One of these options would allow the machine to deliver 2.3 MeV protons to produce epithermal neutrons for treating brain tumors. A second option would provide 15 MeV protons for isotope production. 21 refs., 33 figs.

  18. Hard X-Ray Spectro Microprobe Analysis of Inhomogeneous Solids: A Case Study. Element Distribution and Speciation in Selected Iron Meteorite

    SciTech Connect

    Cavell, R.G.; Feng, R.; Barnes, E.M.; Cavell, P.A.; McCready, A.J.; Webb, M.A.

    2007-06-08

    The hard X-ray microprobe provides an effective methodology for the non-destructive analysis of inhomogeneous materials. Application of X-ray absorption/fluroescence spectroscopy techniques (XANES and EXAFS) permits the speciation of the elements and yields information about the local structural environment. Microfocussed, monochromatic, tunable X-rays allows examination of small areas of micrometer dimensions with spectroscopic procedures. Typically the materials which are presented are thick and cannot be altered for the experiment. This condition introduces difficulties which may compromise the results. Herein we discuss those difficulties and show that the system can yield reliable results in spite of the compromises. Some results are presented on the two iron meteorites we have examined. These specimens are representative of highly inhomogeneous materials and illustrate the difficulties encountered with compositional variations which may occur at sub-millimeter dimensions and also illustrate the difficulties presented by the need to analyze components present at ppm concentration levels in a concentrated matrix. In these particular samples the major constituent is Fe which ranges from 90% to 70%, balanced by Ni which ranges from 10% to 30%. The critical diagnostic trace elements Ga and Ge which must also be analyzed are present at the 80 and 340 ppm level respectively. These diagnostic elements have been shown by EXAFS to be substitutionally placed in the matrix of the major element species in these meteorite samples.

  19. Study on Solar Energetic proton (SEP) Prediction using Regression Technique

    NASA Astrophysics Data System (ADS)

    Yoon, KiChang; Kim, Jae-Hun; Kim, Young Yun; Kwon, Yongki; Wi, Gwan-sik

    2016-07-01

    It is well known that Solar Energetic Proton (SEP) can cause significant effects on electric devices in satellite such as displacement damage and single event effect. It can be dangerous to flight crew/passenger flying high altitude with polar route, and therefore, it is essential that it should be predicted in advance to mitigate radiation exposure risk. However, SEP has been hard to predict, because it is not well-connected solar activities such as solar flare, coronal mass ejection (CME). In this study, we analyzed the variation pattern of proton event from 2000 to 2015, and suggested optimum Gaussian function which can well describe the maximum value of previous event, after then, we finally adopted the regression technique to predict SEP value repetitively. This paper shows that the maximum value and duration of ongoing SEP events can be well predicted, but this model typically has large errors in case of predicting starting point and occurrence of SEP events.

  20. A crystal routine for collimation studies in circular proton accelerators

    NASA Astrophysics Data System (ADS)

    Mirarchi, D.; Hall, G.; Redaelli, S.; Scandale, W.

    2015-07-01

    A routine has been developed to simulate interactions of protons with bent crystals in a version of SixTrack for collimation studies. This routine is optimized to produce high-statistics tracking simulations for a highly efficient collimation system, like the one of the CERN Large Hadron Collider (LHC). The routine has recently been reviewed and improved through a comparison with experimental data, benchmarked against other codes and updated by adding better models of low-probability interactions. In this paper, data taken with 400 GeV/c proton beams at the CERN-SPS North Area are used to verify the prediction of the routine, including the results of a more recent analysis.

  1. Magnetic Resonance Studies of Proton Loss from Carotenoid Radical Cations

    SciTech Connect

    Kispert, Lowell D; Focsan, A Ligia; Konovalova, Tatyana A; Lawrence, Jesse; Bowman, Michael K; Dixon, David A; Molnar, Peter; Deli, Jozsef

    2007-06-11

    Carotenoids, intrinsic components of reaction centers and pigment-protein complexes in photosynthetic membranes, play a photoprotective role and serve as a secondary electron donor. Before optimum use of carotenoids can be made in artificial photosynthetic systems, their robust nature in living materials requires extensive characterization of their electron transfer, radical trapping ability, stability, structure in and on various hosts, and photochemical behavior. Pulsed ENDOR and 2D-HYSCORE studies combined with DFT calculations reveal that photo-oxidation of natural zeaxanthin (I) and violaxanthin (II) on silica-alumina produces not only the carotenoid radical cations (Car•+) but also neutral radicals (#Car•) by proton loss from the methyl groups at positions 5 or 5', and possibly 9 or 9' and 13 or 13'. Notably, the proton loss favored in I at the 5 position by DFT calculations, is unfavorable in II due to the epoxide at the 5, 6 position. DFT calculations predict the isotropic methyl proton couplings of 8-10 MHz for Car•+ which agree with the ENDOR for carotenoid α-conjugated radical cations. Large α-proton hyperfine coupling constants (>10 MHz) determined from HYSCORE are assigned from the DFT calculations to neutral carotenoid radicals. Proton loss upon photolysis was also examined as a function of carotenoid polarity [Lycopene (III) versus 8'-apo-β-caroten-8'-al (IV)]; hydrogen bonding [Lutein (V) versus III]; host [silica-alumina versus MCM-41 molecular sieve]; and substituted metal in MCM-41. Loss of H+ from the 5(5'), 9(9') or 13(13') methyl positions has importance in photoprotection. Photoprotection involves nonphotochemical quenching (NPQ) in which 1Ch1* decays via energy transfer to the carotenoid which returns to the ground state by thermal dissipation; or via electron transfer to form a charge transfer state (I •+…Chl•-), lower in energy than 1Chl*. Formation of I •+ results in bond lengthening, a mechanism for nonradiative energy

  2. How proton pulse characteristics influence protoacoustic determination of proton-beam range: simulation studies.

    PubMed

    Jones, Kevin C; Seghal, Chandra M; Avery, Stephen

    2016-03-21

    The unique dose deposition of proton beams generates a distinctive thermoacoustic (protoacoustic) signal, which can be used to calculate the proton range. To identify the expected protoacoustic amplitude, frequency, and arrival time for different proton pulse characteristics encountered at hospital-based proton sources, the protoacoustic pressure emissions generated by 150 MeV, pencil-beam proton pulses were simulated in a homogeneous water medium. Proton pulses with Gaussian widths ranging up to 200 μs were considered. The protoacoustic amplitude, frequency, and time-of-flight (TOF) range accuracy were assessed. For TOF calculations, the acoustic pulse arrival time was determined based on multiple features of the wave. Based on the simulations, Gaussian proton pulses can be categorized as Dirac-delta-function-like (FWHM < 4 μs) and longer. For the δ-function-like irradiation, the protoacoustic spectrum peaks at 44.5 kHz and the systematic error in determining the Bragg peak range is <2.6 mm. For longer proton pulses, the spectrum shifts to lower frequencies, and the range calculation systematic error increases (⩽ 23 mm for FWHM of 56 μs). By mapping the protoacoustic peak arrival time to range with simulations, the residual error can be reduced. Using a proton pulse with FWHM = 2 μs results in a maximum signal-to-noise ratio per total dose. Simulations predict that a 300 nA, 150 MeV, FWHM = 4 μs Gaussian proton pulse (8.0 × 10(6) protons, 3.1 cGy dose at the Bragg peak) will generate a 146 mPa pressure wave at 5 cm beyond the Bragg peak. There is an angle dependent systematic error in the protoacoustic TOF range calculations. Placing detectors along the proton beam axis and beyond the Bragg peak minimizes this error. For clinical proton beams, protoacoustic detectors should be sensitive to <400 kHz (for -20 dB). Hospital-based synchrocyclotrons and cyclotrons are promising sources of proton pulses for generating clinically measurable protoacoustic

  3. Radiobiological study by using laser-driven proton beams

    SciTech Connect

    Yogo, A.; Nishikino, M.; Mori, M.; Ogura, K.; Sagisaka, A.; Orimo, S.; Nishiuchi, M.; Pirozhkov, A. S.; Ikegami, M.; Tampo, M.; Sakaki, H.; Suzuki, M.; Daito, I.; Kiriyama, H.; Okada, H.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Nakai, Y.; Kawachi, T.

    2009-07-25

    Particle acceleration driven by high-intensity laser systems is widely attracting interest as a potential alternative to conventional ion acceleration, including ion accelerator applications to tumor therapy. Recent works have shown that a high intensity laser pulse can produce single proton bunches of a high current and a short pulse duration. This unique feature of laser-ion acceleration can lead to progress in the development of novel ion sources. However, there has been no experimental study of the biological effects of laser-driven ion beams. We describe in this report the first demonstrated irradiation effect of laser-accelerated protons on human lung cancer cells. In-vitro A549 cells are irradiated with a proton dose of 20 Gy, resulting in a distinct formation of gamma-H2AX foci as an indicator of DNA double-strand breaks. This is a pioneering result that points to future investigations of the radiobiological effects of laser-driven ion beams. The laser-driven ion beam is apotential excitation source for time-resolved determination of hydroxyl (OH) radical yield, which will explore relationship between the fundamental chemical reactions of radiation effects and consequent biological processes.

  4. Radiobiological study by using laser-driven proton beams

    NASA Astrophysics Data System (ADS)

    Yogo, A.; Sato, K.; Nishikino, M.; Mori, M.; Teshima, T.; Numasaki, H.; Murakami, M.; Demizu, Y.; Akagi, S.; Nagayama, S.; Ogura, K.; Sagisaka, A.; Orimo, S.; Nishiuchi, M.; Pirozhkov, A. S.; Ikegami, M.; Tampo, M.; Sakaki, H.; Suzuki, M.; Daito, I.; Oishi, Y.; Sugiyama, H.; Kiriyama, H.; Okada, H.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Nakai, Y.; Tanoue, M.; Sugiyama, H.; Sasao, H.; Wakai, D.; Kawachi, T.; Nishimura, H.; Bolton, P. R.; Daido, H.

    2009-07-01

    Particle acceleration driven by high-intensity laser systems is widely attracting interest as a potential alternative to conventional ion acceleration, including ion accelerator applications to tumor therapy. Recent works have shown that a high intensity laser pulse can produce single proton bunches of a high current and a short pulse duration. This unique feature of laser-ion acceleration can lead to progress in the development of novel ion sources. However, there has been no experimental study of the biological effects of laser-driven ion beams. We describe in this report the first demonstrated irradiation effect of laser-accelerated protons on human lung cancer cells. In-vitro A549 cells are irradiated with a proton dose of 20 Gy, resulting in a distinct formation of γ-H2AX foci as an indicator of DNA double-strand breaks. This is a pioneering result that points to future investigations of the radiobiological effects of laser-driven ion beams. The laser-driven ion beam is apotential excitation source for time-resolved determination of hydroxyl (OH) radical yield, which will explore relationship between the fundamental chemical reactions of radiation effects and consequent biological processes.

  5. Ion and electron microprobe study of troctolites, norite, and anorthosites from Apollo 14: Evidence for urKREEP assimilation during petrogenesis of Apollo 14 Mg-suite rocks

    SciTech Connect

    Shervais, J.W.; McGee, J.J.

    1998-09-01

    Most of the Moon`s highland crust comprises Fe-rich anorthosites with calcic plagioclase compositions. Subsequent evolution of the highland crust was dominated by troctolites, anorthosites, and norites of the Mg-suite. This plutonic series is characterized by calcic plagioclase, and mafic minerals with high mg{number_sign} (=100{sup *}Mg/[Mg + Fe]). In an effort to distinguish the origin of this important lunar rock series, the authors have analyzed the REE content of primary cumulus phases in ten Mg-suite cumulates using SIMS, along with their major and minor element compositions by electron microprobe analysis. Nine of these samples have high mg{number_sign}s, consistent with their formation from the most primitive parent melts of the Mg-suite. The data presented here show that Mg-suite troctolites and anorthosites preserve major and trace element characteristics acquired during their formation as igneous cumulate rocks and that these characteristics can be used to reconstruct related aspects of the parent magma composition. Data show that primitive cumulates of the Mg-suite crystallized from magmas with REE contents similar to high-K KREEP in both concentration and relative abundance. The highly enriched nature of this parent magma contrasts with its primitive major element characteristics, as pointed out by previous workers. This enigma is best explained by the mixing of residual magma ocean urKREEP melts with ultramagnesian komatiitic partial melts from the deep lunar interior. The data do not support earlier models that invoke crustal metasomatism to enrich the Mg-suite cumulates after formation, or models which call for a superKREEP parent for the troctolites and anorthosites.

  6. Ion microprobe U-Th-Pb geochronology and study of micro-inclusions in zircon from the Himalayan high- and ultrahigh-pressure eclogites, Kaghan Valley of Pakistan

    NASA Astrophysics Data System (ADS)

    Rehman, Hafiz Ur; Kobayash, Katsura; Tsujimori, Tatsuki; Ota, Tsutomu; Yamamoto, Hiroshi; Nakamura, Eizo; Kaneko, Yoshiyuki; Khan, Tahseenullah; Terabayashi, Masaru; Yoshida, Kenta; Hirajima, Takao

    2013-02-01

    We report ion microprobe U-Th-Pb geochronology of in situ zircon from the Himalayan high- and ultrahigh-pressure eclogites, Kaghan Valley of Pakistan. Combined with the textural features, mineral inclusions, cathodoluminescence image information and the U-Th-Pb isotope geochronology, two types of zircons were recognized in Group I and II eclogites. Zircons in Group I eclogites are of considerably large size (>100 μm up to 500 μm). A few grains are euhederal and prismatic, show oscillatory zoning with distinct core-rim luminescence pattern. Several other grains show irregular morphology, mitamictization, embayment and boundary truncations. They contain micro-inclusions such as muscovite, biotite, quartz and albite. Core or middle portions of zircons from Group I eclogites yielded concordant U-Th-Pb age of 267.6 ± 2.4 Ma (MSWD = 8.5), have higher U and Th contents with a Th/U ratio > 1, indicating typical magmatic core domains. Middle and rim or outer portions of these zircons contain inclusions of garnet, omphacite, phengite and these portions show no clear zonation. They yielded discordant values ranging between 210 and 71 Ma, indicating several thermal or Pb-loss events during their growth and recrystalization prior to or during the Himalayan eclogite-facies metamorphism. Zircons in Group II eclogites are smaller in size, prismatic to oval, display patchy or sector zoning and contain abundant inclusions of garnet, omphacite, phengite, quartz, rutile and carbonates. They yielded concordant U-Th-Pb age of 44.9 ± 1.2 Ma (MSWD = 4.9). The lower U and Th contents and a lower Th/U ratio (<0.05) in these zircons suggest their formation from the recrystallization of the older zircons during the Himalayan high and ultrahigh-pressure eclogite-facies metamorphism.

  7. Electron Capture Dissociation Studies of the Fragmentation Patterns of Doubly Protonated and Mixed Protonated-Sodiated Peptoids

    NASA Astrophysics Data System (ADS)

    Bogdanov, Bogdan; Zhao, Xiaoning; Robinson, David B.; Ren, Jianhua

    2014-07-01

    The fragmentation patterns of a group of doubly protonated ([P + 2H]2+) and mixed protonated-sodiated ([P + H + Na]2+) peptide-mimicking oligomers, known as peptoids, have been studied using electron capturing dissociation (ECD) tandem mass spectrometry techniques. For all the peptoids studied, the primary backbone fragmentation occurred at the N-Cα bonds. The N-terminal fragment ions, the C-ions (protonated) and the C'-ions (sodiated) were observed universally for all the peptoids regardless of the types of charge carrier. The C-terminal ions varied depending on the type of charge carrier. The doubly protonated peptoids with at least one basic residue located at a position other than the N-terminus fragmented by producing the Z•-series of ions. In addition, most doubly protonated peptoids also produced the Y-series of ions with notable abundances. The mixed protonated-sodiated peptoids fragmented by yielding the Z•'-series of ions in addition to the C'-series. Chelation between the sodium cation and the amide groups of the peptoid chain might be an important factor that could stabilize both the N-terminal and the C-terminal fragment ions. Regardless of the types of the charge carrier, one notable fragmentation for all the peptoids was the elimination of a benzylic radical from the odd-electron positive ions of the protonated peptoids ([P + 2H]•+) and the sodiated peptoids ([P + H + Na]•+). The study showed potential utility of using the ECD technique for sequencing of peptoid libraries generated by combinatorial chemistry.

  8. A STUDY OF POLARIZED PROTON ACCELERATION IN J-PARC.

    SciTech Connect

    LUCCIO, A.U.; BAI, M.; ROSER, T.

    2006-10-02

    We have studied the feasibility of polarized proton acceleration in rhe J-PARC accelerator facility, consisting of a 400 MeV linac, a 3 GeV rapid cycling synchrotron (RCS) and a 50 GeV synchrotron (MR). We show how the polarization of the beam can be preserved using an rf dipole in the RCS and two superconductive partial helical Siberian snakes in the MR. The lattice of the MR will be modified with the addition of quadrupoles to compensate for the focusing properties of the snakes.

  9. A Study of Polarized Proton Acceleration in J-PARC

    SciTech Connect

    Luccio, A. U.; Bai, M.; Roser, T.; Molodojentsev, A.; Ohmori, C.; Sato, H.; Hatanaka, K.

    2007-06-13

    We have studied the feasibility of polarized proton acceleration in rhe J-PARC accelerator facility, consisting of a 400 MeV linac, a 3 GeV rapid cycling synchrotron (RCS) and a 50 GeV synchrotron (MR). We show how the polarization of the beam can be preserved using an rf dipole in the RCS and two superconductve partial helical Siberian snakes in the MR. The lattice of the MR will be modified with the addition of quadrupoles to compensate for the focusing properties of the snakes.

  10. Studies of beam heating of proton beam profile monitor SEM's

    SciTech Connect

    Pavlovich, Zarko; Osiecki, Thomas H.; Kopp, Sacha E.; /Texas U.

    2005-05-01

    The authors present calculations of the expected temperature rise of proton beam profile monitors due to beam heating. The profile monitors are secondary emission monitors (SEM's) to be made of Titanium foils. The heating is studied to understand whether there is any loss of tension or alignment of such devices. Additionally, calculations of thermally-induced dynamic stress are presented. Ti foil is compared to other materials and also to wire SEM's. The calculations were initially performed for the NuMI beam, where the per-pulse intensity is quite high; for completeness the calculations are also performed for other beam energies and intensities.

  11. The use of a scanning proton microprobe in AIDS research

    NASA Astrophysics Data System (ADS)

    Cholewa, M.; Legge, G. J. F.; Weigold, H.; Holan, G.; Birch, C.

    1993-05-01

    A series of organometallic and inorganic drugs has been synthesized at the CSIRO Division of Chemicals and Polymers. The drugs, which are all polyanions of various size, shape and charge are being tested for their activity for the HIV virus in a continuous human T-lymphocyte line (MT2) and in peripheral blood lymphocytes (PBLs). Determinations of drug activity have been carried out at the Fairfield Hospital's Virology Department. It is important for the drug synthesis programme to develop an understanding of the relationship between polyanion properties and antiviral activity. For this it is essential to establish: (a) whether polyanions enter HIV infected cells, (b) their distribution within these cells, (c) whether this distribution is the same for all polyanions, (d) whether the drugs remain intact (do not dissociate) on entering the cell, (e) the differences between active and inactive drugs of similar structure. Answers to these questions and to others will facilitate the synthesis programme.

  12. Proton Conduction and Defect Studies in Acceptor - Potassium Tantalate Crystals.

    NASA Astrophysics Data System (ADS)

    Lee, Wing Kit

    The protonic transport properties of the cubic perovskite structured crystal KTaO(,3) doped with transition metal ions (Fe('3+), Cu('2+), etc.) are studied. These dopants substitute for the Ta('5+) ions and require oxygen vacancies for charge compensation. Protons are introduced by annealing the doped crystals in water vapor. A sharp IR peak at 3472 cm('-1) is observed at room temperature. This OH('-) band can be removed by vacuum annealing. Undoped crystals are not susceptible to H('+) incorporation. A reaction is proposed for the incorporation of H('+): H(,2)O + V(,o) (--->) O(,o)('x) + 2H(.). A saturation content of H('+) is always attained which is independent of both pH(,2)O and annealing temperature. Impendence analysis is employed to obtain the bulk electrical conductivity, (sigma). The (sigma) of H('+) charged samples is an order of magnitude higher than that without H('+). The activation energy for conduction, E(,H), for H('+) charged samples is close to 1.05 eV, irrespective of nature of dopants. A rough monotonic relation between (sigma) and (alpha)(,OH), the IR absorption coefficient, is observed. Conductivity calculated from diffusion data is in rough agreement with the measured (sigma). In addi- tion, the protonic transport number is found to be almost unity in an electrochemical cell experiment. The position of the IR peak is the same for different dopants, suggesting no association between dopant and H('+). The presence of an EPR axial spectrum in H('+) free Fe-doped samples and its conversion to a cubic spectrum after charging with H('+) favors the suggestion that H('+) dissociates from dopants. No dielectric relaxa- tion peak related to H('+) is ever observed. E(,H) thus corresponds to migrational energy only. The migration of the proton is probably just the jump of H('+) between neighboring O('2-) ions in the direction of O-H vibration. The isotope effect on (sigma) is also studied when H('+) is replaced entirely by D('+). The result is non

  13. Reconstruction for proton computed tomography by tracing proton trajectories – A Monte Carlo study

    PubMed Central

    Li, Tianfang; Liang, Zhengrong; Singanallur, Jayalakshmi V.; Satogata, Todd J.; Williams, David C.; Schulte, Reinhard W.

    2006-01-01

    Proton computed tomography (pCT) has been explored in the past decades because of its unique imaging characteristics, low radiation dose, and its possible use for treatment planning and on-line target localization in proton therapy. However, reconstruction of pCT images is challenging because the proton path within the object to be imaged is statistically affected by multiple Coulomb scattering. In this paper, we employ GEANT4-based Monte Carlo simulations of the two-dimensional pCT reconstruction of an elliptical phantom to investigate the possible use of the Algebraic Reconstruction Technique (ART) with three different path-estimation methods for pCT reconstruction. The first method assumes a straight-line path (SLP) connecting the proton entry and exit positions, the second method adapts the most-likely path (MLP) theoretically determined for a uniform medium, and the third method employs a cubic spline path (CSP). The ART reconstructions showed progressive improvement of spatial resolution when going from the SLP (2 line pairs (lp) cm-1) to the curved CSP and MLP path estimates (5 lp cm-1). The MLP-based ART algorithm had the fastest convergence and smallest residual error of all three estimates. This work demonstrates the advantage of tracking curved proton paths in conjunction with the ART algorithm and curved path estimates. PMID:16878573

  14. Reconstruction for proton computed tomography by tracing proton trajectories: A Monte Carlo study

    SciTech Connect

    Li Tianfang; Liang Zhengrong; Singanallur, Jayalakshmi V.; Satogata, Todd J.; Williams, David C.; Schulte, Reinhard W.

    2006-03-15

    Proton computed tomography (pCT) has been explored in the past decades because of its unique imaging characteristics, low radiation dose, and its possible use for treatment planning and on-line target localization in proton therapy. However, reconstruction of pCT images is challenging because the proton path within the object to be imaged is statistically affected by multiple Coulomb scattering. In this paper, we employ GEANT4-based Monte Carlo simulations of the two-dimensional pCT reconstruction of an elliptical phantom to investigate the possible use of the algebraic reconstruction technique (ART) with three different path-estimation methods for pCT reconstruction. The first method assumes a straight-line path (SLP) connecting the proton entry and exit positions, the second method adapts the most-likely path (MLP) theoretically determined for a uniform medium, and the third method employs a cubic spline path (CSP). The ART reconstructions showed progressive improvement of spatial resolution when going from the SLP [2 line pairs (lp) cm{sup -1}] to the curved CSP and MLP path estimates (5 lp cm{sup -1}). The MLP-based ART algorithm had the fastest convergence and smallest residual error of all three estimates. This work demonstrates the advantage of tracking curved proton paths in conjunction with the ART algorithm and curved path estimates.

  15. Inelastic proton scattering of Sn isotopes studied with GRETINA

    NASA Astrophysics Data System (ADS)

    Campbell, Christopher

    2014-03-01

    The chain of semi-magic Sn nuclei, with many stable isotopes, has been a fertile ground for experimental and theoretical studies. Encompassing a major neutron shell from N = 50 to 82, the properties and structure of these nuclei provided important data for the development of the pairing-plus-quadrupole model. Recent experimental information on B(E2) for 106,108,110,112Sn came as a surprise as it indicated a larger collectivity than the predicted parabolic trend of quadrupole collectivity. These data, instead, show an unexpectedly flat trend even as the number of valence particles is reduced from 12 to 6. To fully understand how collectivity is evolving in these isotopes, 108,110,112Sn have been studied using thick-target, inelastic proton scattering with GRETINA tagging inelastic scattering events by detecting gamma-rays from the prompt decay of states excited in the reaction. We will present the trend of 2 + excitation cross-sections, the deduced quadrupole deformation parameters, and observations of other low-lying collective states. Comparison of these (p,p') quadrupole deformation parameters with B(E2) data will provide new insights into the relative importance of proton and neutron contributions to collectivity in these nuclei. GRETINA was funded by the US DOE - Office of Science. Operation of the array at NSCL is supported by NSF under Cooperative Agreement PHY-1102511(NSCL) and DOE under grant DE-AC02-05CH11231(LBNL).

  16. Scaling of SEU mapping and cross section, and proton induced SEU at reduced supply voltage

    SciTech Connect

    Barak, J.; Levinson, J.; Akkerman, A.

    1999-12-01

    New experimental study of heavy ion and proton induced SEU at reduced voltage (i.e., reduced critical charge) reveals interesting results. It is shown that the heavy ion cross section and microprobe mapping scale like the threshold LET and the parameter, which is almost invariant under bias changes, is the effective charge collection depth. For studying proton induced SEU and surface-barrier-detector spectra the authors use protons with energies from 5.6 to 300 MeV. The results are analyzed in view of the processes involved in low energy deposition by protons. Detailed calculations show the importance of straggling in proton direct ionization which might be the leading process in very sensitive devices like photodiodes.

  17. Perspective study of exotics and flavour baryons in antiproton-proton annihilation and proton-proton collisions

    NASA Astrophysics Data System (ADS)

    Barabanov, Mikhail; Vodopyanov, Alexander

    2016-07-01

    Abstract. The spectroscopy of exotic states with hidden charm is discussed. Together with charmonium, these provide a good tool for testing theories of the strong interactions including both perturbative and non-perturbative QCD, lattice QCD, potential and other phenomenological models. An elaborated analysis of exotics spectrum is given, and attempts to interpret recent experimentally observed states with masses above the DD̅ threshold region are considered. Experimental results from different collaborations (BES, BaBar, Belle, LHCb) are analyzed with special attention given to recently discovered hidden charm states. Some of these states can be interpreted as higher-lying charmonium states and others as tetraquarks with hidden charm. It has been shown that charged/neutral tetraquarks must have their neutral/charge partners with mass values differ by at most a few MeV/c2, hypotheses that tend to coincide with those proposed by Maiani and Polosa. However, measurements of different decay modes are needed before firm conclusions can be made. These data can be derived directly from the experiments using ahigh quality antiproton beam with momentum up to 15 GeV/c and proton-proton collisions with momentum up to 26 GeV/c. DD

  18. A performance study of the Loma Linda proton medical accelerator

    SciTech Connect

    Coutrakon, G.; Hubbard, J.; Johanning, J.; Maudsley, G.; Slaton, T.; Morton, P. )

    1994-11-01

    More than three years have passed since Loma Linda treated the first cancer patient with the world's first proton accelerator dedicated to radiation therapy. Since that time, over 1000 patients have completed treatments and the facility currently treats more than 45 patients per day. With a typical intensity of 3[times]10[sup 10] protons per pulse and 27 pulses per minute, dose rates of 90--100 cGy/min are easily achieved on a 20-cm diameter field. In most cases, patient treatment times are 2 min, much less than the patient alignment time required before each treatment. Nevertheless, there is considerable medical interest in increasing field sizes up to 40-cm diameter while keeping dose rates high and treatment times low. In this article, beam measurements relevant to intensity studies are presented and possible accelerator modifications for upgrades are proposed. It is shown that nearly all intensity losses can be ascribed to the large momentum spread of the injected beam and occur at or near the injection energy of 2 MeV. The agreement between calculations and measurements appears quite good. In addition, optimum beam characteristics for a new injector are discussed based upon the momentum acceptance and space charge limits of the Loma Linda synchrotron.

  19. A performance study of the Loma Linda proton medical accelerator.

    PubMed

    Coutrakon, G; Hubbard, J; Johanning, J; Maudsley, G; Slaton, T; Morton, P

    1994-11-01

    More than three years have passed since Loma Linda treated the first cancer patient with the world's first proton accelerator dedicated to radiation therapy. Since that time, over 1000 patients have completed treatments and the facility currently treats more than 45 patients per day. With a typical intensity of 3 x 10(10) protons per pulse and 27 pulses per minute, dose rates of 90-100 cGy/min are easily achieved on a 20-cm diameter field. In most cases, patient treatment times are 2 min, much less than the patient alignment time required before each treatment. Nevertheless, there is considerable medical interest in increasing field sizes up to 40-cm diameter while keeping dose rates high and treatment times low. In this article, beam measurements relevant to intensity studies are presented and possible accelerator modifications for upgrades are proposed. It is shown that nearly all intensity losses can be ascribed to the large momentum spread of the injected beam and occur at or near the injection energy of 2 MeV. The agreement between calculations and measurements appears quite good. In addition, optimum beam characteristics for a new injector are discussed based upon the momentum acceptance and space charge limits of the Loma Linda synchrotron. PMID:7891629

  20. A simulation study of Methane by proton at low energies

    NASA Astrophysics Data System (ADS)

    Quashie, Edwin E.; Correaa, Alfredo A.; Schwegler, Eric R.; Saha, Bidhan C.

    2014-05-01

    Proton impact molecular collisions have received considerable attentions over last few decades due to wide applications in various fields such as plasma physics, astrophysics, material science, and radiation therapy. Methane is the simplest hydrocarbon and has recently been detected in the atmosphere of the outer planets. In addition to provide the fundamental information, the charge exchange studies remain critical for understanding the phenomena in studies of comets, the solar wind, and space weather. The charge exchange processes in recent years have been used as diagnostics for temperature and transport. Using the time dependent density functional theory our results for both the elastic and inelastic scattering will be presented. Supported by National Nuclear Security Agency & Lawrence Livermore National Laboratory.

  1. Theoretical studies of proton emission from drip-line nuclei

    SciTech Connect

    Ferreira, L. S.; Maglione, E.; Ring, P.

    2011-11-30

    In this work, we discuss proton radioactivity from spherical nuclei in a modern perspective, based on a fully self--consistent relativistic density functional calculation with fundamental interactions.

  2. Origins of PM10 determined by the micro-proton induced X-ray emission spectra of single aerosol particles

    SciTech Connect

    Yue, W.S.; Li, X.L.; Wan, T.M.; Liu, J.F.; Zhang, G.L.; Li, Y.

    2006-06-15

    The micro-proton induced X-ray emission (micro-PIXE) spectrum of a single aerosol particle (SAP) was considered as its fingerprint for tracing its origin. A proton microprobe was used to extract fingerprints of SAPs. Environmental monitoring samples of PM10 were collected from a heavy industrial area of Shanghai and were analyzed by proton microprobe for finding their pollution sources. In order to find the sources of SAPs collected from environmental monitoring sites, a fingerprint database of SAPS collected from various pollution Sources was established. The origins of samples collected through environmental monitoring were identified by comparison of the micro-PIXE spectra of SAPs with those of SAPs in the fingerprint database using a pattern recognition technique. The results of this study show that most of the measured PM10 is derived from metallurgic industry, soil dust, coal combustion, automobile exhaust, and motorcycle exhaust. The study also shows that the proton microprobe is an ideal tool for the analysis of SAPs. The unidentified particles of PM10 are classified into seven classes by hierarchical cluster analysis based on the element peak intensity in the spectra.

  3. Proton dose calculation on scatter-corrected CBCT image: Feasibility study for adaptive proton therapy

    PubMed Central

    Park, Yang-Kyun; Sharp, Gregory C.; Phillips, Justin; Winey, Brian A.

    2015-01-01

    Purpose: To demonstrate the feasibility of proton dose calculation on scatter-corrected cone-beam computed tomographic (CBCT) images for the purpose of adaptive proton therapy. Methods: CBCT projection images were acquired from anthropomorphic phantoms and a prostate patient using an on-board imaging system of an Elekta infinity linear accelerator. Two previously introduced techniques were used to correct the scattered x-rays in the raw projection images: uniform scatter correction (CBCTus) and a priori CT-based scatter correction (CBCTap). CBCT images were reconstructed using a standard FDK algorithm and GPU-based reconstruction toolkit. Soft tissue ROI-based HU shifting was used to improve HU accuracy of the uncorrected CBCT images and CBCTus, while no HU change was applied to the CBCTap. The degree of equivalence of the corrected CBCT images with respect to the reference CT image (CTref) was evaluated by using angular profiles of water equivalent path length (WEPL) and passively scattered proton treatment plans. The CBCTap was further evaluated in more realistic scenarios such as rectal filling and weight loss to assess the effect of mismatched prior information on the corrected images. Results: The uncorrected CBCT and CBCTus images demonstrated substantial WEPL discrepancies (7.3 ± 5.3 mm and 11.1 ± 6.6 mm, respectively) with respect to the CTref, while the CBCTap images showed substantially reduced WEPL errors (2.4 ± 2.0 mm). Similarly, the CBCTap-based treatment plans demonstrated a high pass rate (96.0% ± 2.5% in 2 mm/2% criteria) in a 3D gamma analysis. Conclusions: A priori CT-based scatter correction technique was shown to be promising for adaptive proton therapy, as it achieved equivalent proton dose distributions and water equivalent path lengths compared to those of a reference CT in a selection of anthropomorphic phantoms. PMID:26233175

  4. Macroparticle simulation studies of a proton beam haloexperiment

    SciTech Connect

    Qiang, J.; Colestock, P.L.; Gilpatrick, D.; Smith, H.V.; Wangler,T.P.; Schulze, M.E.

    2002-09-12

    We report macroparticle simulations for comparison withmeasured results from a proton beam-halo experiment in a 52-quadrupoleperiodic-focusing channel. An important issue is that the inputphase-space distribution is not experimentally known. Three differentinitial distributions with different shapes predict different beamprofiles in the transport system. Simulations have been fairly successfulin reproducing the core of the measured matched-beam profiles and thetrend of emittance growth as a function of mismatch factor, butunderestimate the growth rate of halo and emittance for mismatched beams.In this study, we find that knowledge of the Courant-Snyder parametersand emittances of the input beam is not sufficient for reliableprediction of the halo. Input distributions iwth greater population inthe tails produce larger rates of emittance growth, a result that isqualitatively consistent with the particle-core model of halo formationin mismatched beams.

  5. Protonation of caffeine: A theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Bahrami, Hamed; Tabrizchi, Mahmoud; Farrokhpour, Hossein

    2013-03-01

    Protonation of caffeine was examined by ion mobility spectrometry equipped with two ionization sources, corona discharge (CD) and UV photoionization. Three peaks were observed in ion mobility spectrum by simultaneously running the two ionization sources. Experimental and theoretical evidence was collected to link the observed peaks to caffeine related ionic species. One peak was attributed to the M+ ion while the other two were assigned to different protonated isomers of caffeine. In the case of CD ionization source, it was observed that different sites of caffeine compete for protonation and their relative intensities, depends on the sample concentration as well as the nature of the reactant ions. The new concept of "internal proton affinity" (IPA) was defined to express the tendency of holding the added proton for each atom in a molecule.

  6. Data acquisition with a nuclear microprobe

    SciTech Connect

    Maggiore, C.

    1980-01-01

    Spatially resolved information from the near surfaces of materials can be obtained with a nuclear microprobe. The spatial resolution is determined by the optics of the instrument and radiation damage in the specimen. Two- and three-dimensional maps of elemental concentration may be obtained from the near surfaces of materials. Data are acquired by repeated scans of a constantly moving beam over the region of interest or by counting for a preset integrated charge at each specimen location.

  7. Computed tomography with a low-intensity proton flux: results of a Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Schulte, Reinhard W.; Klock, Margio C. L.; Bashkirov, Vladimir; Evseev, Ivan G.; de Assis, Joaquim T.; Yevseyeva, Olga; Lopes, Ricardo T.; Li, Tianfang; Williams, David C.; Wroe, Andrew J.; Schelin, Hugo R.

    2004-10-01

    Conformal proton radiation therapy requires accurate prediction of the Bragg peak position. This problem may be solved by using protons rather than conventional x-rays to determine the relative electron density distribution via proton computed tomography (proton CT). However, proton CT has its own limitations, which need to be carefully studied before this technique can be introduced into routine clinical practice. In this work, we have used analytical relationships as well as the Monte Carlo simulation tool GEANT4 to study the principal resolution limits of proton CT. The GEANT4 simulations were validated by comparing them to predictions of the Bethe Bloch theory and Tschalar's theory of energy loss straggling, and were found to be in good agreement. The relationship between phantom thickness, initial energy, and the relative electron density uncertainty was systematically investigated to estimate the number of protons and dose needed to obtain a given density resolution. The predictions of this study were verified by simulating the performance of a hypothetical proton CT scanner when imaging a cylindrical water phantom with embedded density inhomogeneities. We show that a reasonable density resolution can be achieved with a relatively small number of protons, thus providing a possible dose advantage over x-ray CT.

  8. Proton NMR studies of functionalized nanoparticles in aqueous environments

    NASA Astrophysics Data System (ADS)

    Tataurova, Yulia Nikolaevna

    in high-resolution NMR spectra. This technique is selective for protons on the surface organic functional groups due to their motional averaging in solution. In this study, 1H solution NMR spectroscopy was used to investigate the interface of the organic functional groups in D2O. The pKa for these functional groups covalently bound to the surface of nanoparticles was determined using an NMR-pH titration method based on the variation in the proton chemical shift for the alkyl group protons closest to the amine group with pH. The adsorption of toxic contaminants (chromate and arsenate anions) on the surface of functionalized silicalite-1 and mesoporous silica nanoparticles has been studied by 1H solution NMR spectroscopy. With this method, the surface bound contaminants are detected. The analysis of the intensity and position of these peaks allows quantitative assessment of the relative amounts of functional groups with adsorbed metal ions. These results demonstrate the sensitivity of solution NMR spectroscopy to the electronic environment and structure of the surface functional groups on porous nanomaterials.

  9. Investigation of elemental distribution in human femoral head by PIXE and SRXRF microprobe

    NASA Astrophysics Data System (ADS)

    Zhang, Y. X.; Wang, Y. S.; Zhang, Y. P.; Zhang, G. L.; Huang, Y. Y.; He, W.

    2007-07-01

    In order to study the distribution and possible degenerative processes inducing the loss of inorganic substances in bone and to provide a scientific basis for the prevention and therapy of osteoporosis, proton induced X-ray emission (PIXE) method is used for the determination of elemental concentrations in femoral heads from five autopsies and seven patients with femoral neck fractures. Synchrotron radiation X-ray fluorescence (SRXRF) microprobe analysis technique is used to scan a slice of the femoral head from its periphery to its center, via cartilage, compact and spongy zones. The specimen preparation and experiment procedure are described in detail. The results show that the concentrations of P, Ca, Fe, Cu, Sr in the control group are higher than those in the patient group, but the concentrations of S, K, Zn, Mn are not significantly different. The quantitative results of elemental distribution, such as Ca, P, K, Fe, Zn, Sr and Pb in bone slice tissue including cartilage, substantial compact and substantial spongy, are investigated. The data obtained show that the concentrations of Ca, P, K, (the major elements of bone composition), are obviously low in both spongy and cartilage zones in the patient group, but there are no remarkable differences in the compact zone. Combined with the correlations between P, K, Zn, Sr and Ca, the loss mechanism of minerals and the physiological functions of some metal elements in bone are also discussed.

  10. Proof of principle study of the use of a CMOS active pixel sensor for proton radiography

    SciTech Connect

    Seco, Joao; Depauw, Nicolas

    2011-02-15

    Purpose: Proof of principle study of the use of a CMOS active pixel sensor (APS) in producing proton radiographic images using the proton beam at the Massachusetts General Hospital (MGH). Methods: A CMOS APS, previously tested for use in s-ray radiation therapy applications, was used for proton beam radiographic imaging at the MGH. Two different setups were used as a proof of principle that CMOS can be used as proton imaging device: (i) a pen with two metal screws to assess spatial resolution of the CMOS and (ii) a phantom with lung tissue, bone tissue, and water to assess tissue contrast of the CMOS. The sensor was then traversed by a double scattered monoenergetic proton beam at 117 MeV, and the energy deposition inside the detector was recorded to assess its energy response. Conventional x-ray images with similar setup at voltages of 70 kVp and proton images using commercial Gafchromic EBT 2 and Kodak X-Omat V films were also taken for comparison purposes. Results: Images were successfully acquired and compared to x-ray kVp and proton EBT2/X-Omat film images. The spatial resolution of the CMOS detector image is subjectively comparable to the EBT2 and Kodak X-Omat V film images obtained at the same object-detector distance. X-rays have apparent higher spatial resolution than the CMOS. However, further studies with different commercial films using proton beam irradiation demonstrate that the distance of the detector to the object is important to the amount of proton scatter contributing to the proton image. Proton images obtained with films at different distances from the source indicate that proton scatter significantly affects the CMOS image quality. Conclusion: Proton radiographic images were successfully acquired at MGH using a CMOS active pixel sensor detector. The CMOS demonstrated spatial resolution subjectively comparable to films at the same object-detector distance. Further work will be done in order to establish the spatial and energy resolution of the

  11. In-beam studies of proton emitters using the Recoil-Decay Tagging method

    SciTech Connect

    Seweryniak, D.; Woods, P. J.; Ressler, J.; Davids, C. N.; Heinz, A.; Sonzogni, A.; Uusitalo, J.; Walters, W. B.; Caggiano, J.; Carpenter, M. P.; Cizewski, J. A.; Davinson, T.; Ding, K. Y.; Fotiades, N.; Garg, U.; Janssens, R. V. F.; Khoo, T.-L.; Kondev, F.; Lauritsen, T.; Lister, C. J.; Reiter, P.; Shergur, J.; Wiedenhoever, I.

    2000-01-19

    The last five years have witnessed a rapid increase in the volume of data on proton decaying nuclei. The path was led by decay studies with recoil mass separators equipped with double-sided Si strip detectors. The properties of many proton-decaying states were deduced, which triggered renewed theoretical interest in the process of proton decay. The decay experiments were closely followed by in-beam {gamma}-ray studies which extended one's knowledge of high-spin states of proton emitters. The unparalleled selectivity of the Recoil-Decay Tagging method combined with the high efficiency of large arrays of Ge detectors allowed, despite small cross sections and overwhelming background from strong reaction channels, the observation of excited states in several proton emitters. Recently, in-beam studies of the deformed proton emitters {sup 141}Ho and {sup 131}Eu have been performed with the GAMMASPHERE array of Ge detectors and the Fragment Mass Analyzer at ATLAS. Evidence was found for rotational bands in {sup 141}Ho and {sup 131}Eu. The deformations and the single-particle configurations proposed for the proton emitting states from the earlier proton-decay studies were confronted with the assignments deduced based on the in-beam data. It should be noted that the cross section for populating {sup 131}Eu is only about 50 nb, and it represents the weakest channel ever studied in an in-beam experiment.

  12. Impact of high energy high intensity proton beams on targets: Case studies for Super Proton Synchrotron and Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Tahir, N. A.; Sancho, J. Blanco; Shutov, A.; Schmidt, R.; Piriz, A. R.

    2012-05-01

    The Large Hadron Collider (LHC) is designed to collide two proton beams with unprecedented particle energy of 7 TeV. Each beam comprises 2808 bunches and the separation between two neighboring bunches is 25 ns. The energy stored in each beam is 362 MJ, sufficient to melt 500 kg copper. Safety of operation is very important when working with such powerful beams. An accidental release of even a very small fraction of the beam energy can result in severe damage to the equipment. The machine protection system is essential to handle all types of possible accidental hazards; however, it is important to know about possible consequences of failures. One of the critical failure scenarios is when the entire beam is lost at a single point. In this paper we present detailed numerical simulations of the full impact of one LHC beam on a cylindrical solid carbon target. First, the energy deposition by the protons is calculated with the FLUKA code and this energy deposition is used in the BIG2 code to study the corresponding thermodynamic and the hydrodynamic response of the target that leads to a reduction in the density. The modified density distribution is used in FLUKA to calculate new energy loss distribution and the two codes are thus run iteratively. A suitable iteration step is considered to be the time interval during which the target density along the axis decreases by 15%-20%. Our simulations suggest that the full LHC proton beam penetrates up to 25 m in solid carbon whereas the range of the shower from a single proton in solid carbon is just about 3 m (hydrodynamic tunneling effect). It is planned to perform experiments at the experimental facility HiRadMat (High Radiation Materials) at CERN using the proton beam from the Super Proton Synchrotron (SPS), to compare experimental results with the theoretical predictions. Therefore simulations of the response of a solid copper cylindrical target hit by the SPS beam were performed. The particle energy in the SPS beam is 440

  13. Proton nuclear magnetic resonance studies on brain edema

    SciTech Connect

    Naruse, S.; Horikawa, Y.; Tanaka, C.; Hirakawa, K.; Nishikawa, H.; Yoshizaki, K.

    1982-06-01

    The water in normal and edematous brain tissues of rats was studied by the pulse nuclear magnetic resonance (NMR) technique, measuring the longitudinal relaxation time (T1) and the transverse relaxation time (T2). In the normal brain, T1 and T2 were single components, both shorter than in pure water. Prolongation and separation of T2 into two components, one fast and one slow, were the characteristic findings in brain edema induced by both cold injury and triethyl tin (TET), although some differences between the two types of edema existed in the content of the lesion and in the degree of changes in T1 and T2 values. Quantitative analysis of T1 and T2 values in their time course relating to water content demonstrated that prolongation of T1 referred to the volume of increased water in tissues examined, and that two phases of T2 reflected the distribution and the content of the edema fluid. From the analysis of the slow component of T2 versus water content during edema formation, it was demonstrated that the increase in edema fluid was steady, and its content was constant during formation of TET-induced edema. On the contrary, during the formation of cold-injury edema, water-rich edema fluid increased during the initial few hours, and protein-rich edema fluid increased thereafter. It was concluded that proton NMR relaxation time measurements may provide new understanding in the field of brain edema research.

  14. Study of {beta}-Decay in the Proton-Neutron Interacting Boson-Fermion Model

    SciTech Connect

    Zuffi, L.; Brant, S.; Yoshida, N.

    2006-04-26

    We study {beta}-decay in odd-A nuclei together with the energy levels and other properties in the proton-neutron interacting-boson-fermion model. We also report on the preliminary results in the odd-odd nuclei in the proton-neutron interacting boson-fermion-fermion model.

  15. Boron analysis by electron microprobe using MoB4C layered synthetic crystals

    USGS Publications Warehouse

    McGee, J.J.; Slack, J.F.; Herrington, C.R.

    1991-01-01

    Preliminary electron microprobe studies of B distribution in minerals have been carried out using MoB4C-layered synthetic crystals to improve analytical sensitivity for B. Any microprobe measurements of the B contents of minerals using this crystal must include analyses for Cl to assess and correct for the interference of Cl X-rays on the BK?? peak. Microprobe analyses for B can be made routinely in tourmaline and other B-rich minerals, and minor B contents also can be determined in common rock-forming minerals. Incorporation of unusually high B contents in minerals other than borosilicates has been discovered in prograde and retrograde minerals in tourmalinites from the Broken Hill district, Australia, and may reflect high B activities produced during the metamorphism of tourmaline-rich rocks. -from Authors

  16. Technical aspects of nuclear microprobe analysis of senile plaques from alzheimer patients

    NASA Astrophysics Data System (ADS)

    Larsson, N. P.-O.; Tapper, U. A. S.; Sturesson, K.; Odselius, R.; Brun, A.

    1990-04-01

    Alzheimer's disease, a common form of senile dementia, has been proposed to be caused by aluminium. One of the interesting structures to be studied, senile plaque cores in the brain, have centres of only about 10 μm. We have investigated the possibility of applying nuclear microprobes to sections containing senile plaques. An alternative staining procedure, TMToluidin blue staining using a spray technique, is also presented. An outline is given of a procedure for preparing senile plaque specimens for nuclear microprobe analysis. This includes a technique for accurate ion beam positioning, utilizing electron microscopy-grids. The subject may be of general interest since sample preparation is one of the most important aspects in microprobe analysis of biological matter.

  17. The Debrecen Scanning Nuclear Microprobe and its Applications in Biology and Environmental Science

    SciTech Connect

    Kertesz, Zsofia

    2007-11-26

    Nuclear microscopy is one of the most powerful tools which are able to determine quantitative trace element distributions in complex samples on a microscopic scale. The advantage of nuclear microprobes are that different ion beam analytical techniques, like PIXE, RBS, STIM and NRA can be applied at the same time allowing the determination of the sample structure, major, minor and trace element distribution simultaneously.In this paper a nuclear microprobe setup developed for the microanalysis of thin complex samples of organic matrix at the Debrecen Scanning Nuclear Microprobe Facility is presented. The application of nuclear microscopy in life sciences is shown through an example, the study of penetration of TiO{sub 2} nanoparticles of bodycare cosmetics in skin layers.

  18. Laser Microprobe Mass Spectrometry 1: Basic Principles and Performance Characteristics.

    ERIC Educational Resources Information Center

    Denoyer, Eric; And Others

    1982-01-01

    Describes the historical development, performance characteristics (sample requirements, analysis time, ionization characteristics, speciation capabilities, and figures of merit), and applications of laser microprobe mass spectrometry. (JN)

  19. MicroProbe Small Unmanned Aerial System

    NASA Technical Reports Server (NTRS)

    Bland, Geoffrey; Miles, Ted

    2012-01-01

    The MicroProbe unmanned aerial system (UAS) concept incorporates twin electric motors mounted on the vehicle wing, thus enabling an aerodynamically and environmentally clean nose area for atmospheric sensors. A payload bay is also incorporated in the fuselage to accommodate remote sensing instruments. A key feature of this concept is lightweight construction combined with low flying speeds to minimize kinetic energy and associated hazards, as well as maximizing spatial resolution. This type of aerial platform is needed for Earth science research and environmental monitoring. There were no vehicles of this type known to exist previously.

  20. Friction microprobe investigation of particle layer effects on sliding friction

    SciTech Connect

    Blau, P.J.

    1993-01-01

    Interfacial particles (third-bodies), resulting from wear or external contamination, can alter and even dominate the frictional behavior of solid-solid sliding in the absence of effective particle removal processes (e.g., lubricant flow). A unique friction microprobe, developed at Oak Ridge National Laboratory, was used to conduct fine- scale friction studies using 1.0 mm diameter stainless steel spheres sliding on several sizes of loose layers of fine aluminum oxide powders on both aluminum and alumina surfaces. Conventional, pin-on-disk experiments were conducted to compare behavior with the friction microprobe results. The behavior of the relatively thick particle layers was found to be independent of the nature of underlying substrate, substantiating previous work by other investigators. The time-dependent behavior of friction, for a spherical macrocontact starting from rest, could generally be represented by a series of five rather distinct phases involving static compression, slider breakaway, transition to steady state, and dynamic layer instability. A friction model for the steady state condition, which incorporates lamellar powder layer behavior, is described.

  1. Carrier phases for iodine in the Allende meteorite and their associated Xe-129(r)/I-127 ratios - A laser microprobe study

    NASA Technical Reports Server (NTRS)

    Kirschbaum, C.

    1988-01-01

    This paper presents the results of a study of the carrier phases of iodine in the Allende meteorite and their associated Xe-129(r)/I-127 ratios, obtained using a new high-sensitivity low-blank mass spectrometer coupled with a low-blank laser extraction system. Two types of experiments were performed: a survey of the Xe-129(r) amounts in unirradiated specimens of fine-grained assemblages and individual coarse mineral grains, and a study of the relationship between chlorine and iodine in irradiated samples of the inclusions, in which the Xe-129(r)/I-127 ratios were determined for various minerals. As a by-product of these measurements, the Ar-40/Ar-39 ages were obtained along with some results on trapped Xe components. A schematic diagram of the new mass spectrometer system is included.

  2. Molecular organization in the native state of woody tissue: Studies of tertiary structure using the Raman microprobe Solid State [sup 13]C NMR and biomimetic tertiary aggregates

    SciTech Connect

    Atalla, R.H.

    1992-01-01

    A number of new approaches to the study of native wood tissue complementary to our earlier Raman spectroscopy including solid state [sup 13]C NMR and X-ray diffractometry. A wide variety of native cellulosic tissues were examined which led to the generation of biomimetic tertiary aggregates which simulate states of aggregation characteristic of cell walls. We have also explored charge transport characteristics of lignified tissue. Our Raman spectroscopic studies have advanced our understanding of key spectral features and confirmed the variability of the patterns of orientation of lignin reported earlier. A major effort was dedicated to assessing the contributions of electronic factors such as conjugation and the resonance Raman effect to enhancement of the spectra features associated with lignin. We have now established a solid foundation for spectral mapping of different regions in cell walls.

  3. Laser-induced oxidation kinetics of bismuth surface microdroplets on GaAsBi studied in situ by Raman microprobe analysis.

    PubMed

    Steele, J A; Lewis, R A

    2014-12-29

    We report the cw-laser-induced oxidation of molecular-beam-epitaxy grown GaAsBi bismuth surface microdroplets investigated in situ by micro-Raman spectroscopy under ambient conditions as a function of irradiation power and time. Our results reveal the surface droplets are high-purity crystalline bismuth and the resultant Bi2O3 transformation to be β-phase and stable at room temperature. A detailed Raman study of Bi microdroplet oxidation kinetics yields insights into the laser-induced oxidation process and offers useful real-time diagnostics. The temporal evolution of new β-Bi2O3 Raman modes is shown to be well described by Johnson-Mehl-Avrami-Kolmogorov kinetic transformation theory and while this study limits itself to the laser-induced oxidation of GaAsBi bismuth surface droplets, the results will find application within the wider context of bismuth laser-induced oxidation and direct Raman laser processing. PMID:25607191

  4. The application of reflected light microscopy, scanning electron microscopy-energy dispersive spectroscopy, Auger electron spectroscopy and electron microprobe analysis to the study of dusts

    SciTech Connect

    Hagni, A.M.; Hagni, R.D. . Dept. of Geology and Geophysics)

    1993-03-01

    Over 500,000 tons of electric arc furnace (EAF) dust is generated each year in the US. The mineralogy and characterization of this dust is being studied to determine the phases and relationships of the valuable zinc, the hazardous lead, cadmium, and chromium, and the deleterious chlorine and fluorine. EAF dust averages 15--20% zinc and is therefore a potential source for 100,000 tons of zinc per year. The major mineralogical phases of EAF dust are franklinite (ZnFe[sub 2]O[sub 4]), magnetite (FeFe[sub 2]O[sub 4]), jacobsite (MnFe[sub 2]O[sub 4]), solid solutions between franklinite-magnetite-jacobsite, and zincite (ZnO). Franklinite, magnetite, and jacobsite solid solutions commonly are cruciform or dendritic crystals in a Ca-Fe-Si matrix and contain up to 5% chromium. Magnetite also occurs as spheres partially oxidized to hematite (Fe[sub 2]O[sub 3]) along its octahedral planes. The dust particles are predominantly in the form of spheres and broken spheres, ranging in size from 200 [mu]m to less than 1 [mu]m. Although many spheres are in the size ranges of 40--50 [mu]m and 10--20 [mu]m, most are less than 1 [mu]m in diameter. Automated scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) probed 118 particles in search of chlorine phases. Chlorine-bearing lime (CaO) was identified by that SEM study. In addition, chlorine is present as hydrophylite (CaCl[sub 2]) and sylvite (KCl). Auger electron spectroscopy (AES) was used to sputter the outer 180[angstrom] layer of the dust particles to search for the possible presence of cotunnite (PbCl[sub 2]) coatings, but none were detected. Minor phases detected include chalcopyrite (CuFeS[sub 2]), sphalerite (ZnS), pyrite (FeS[sub 2]), and coke.

  5. Proton Emission Studies at GSI in the 1980s

    SciTech Connect

    Hofmann, Sigurd

    2000-12-31

    This article describes the experiments that were performed during the first decade of the operation of UNILAC, GSI-Darmstadt, at the recoil separator SHIP and the on-line mass separator. The measurements resulted in the discovery of the first radioactive ground state proton emitters, {sup 151}Lu and {sup 147}Tm.

  6. Scanning electron microscope and dye penetration test: comparison of root canal preparation with 15 F CO2 laser microprobe versus conventional method--in vivo study

    NASA Astrophysics Data System (ADS)

    Kesler, Gavriel; Koren, Rumelia; Kesler, Anat; Hay, Nissim; Gal, Rivka

    1999-05-01

    The study was conducted on 30 vital maxillary or mandibulary teeth destined for extraction due to periodontal problems. 21 were experimentally treated with pulsed CO2 laser delivered by a newly developed fiber and 9 teeth represented the control group. The micro probe is a flexible, hollow, metal fiber, 300 μm in diameter and 20 mm in length, coupled onto a handpiece, with the following radiation parameters: wavelength-10.6μm pulse duration-50m.sec; energy per pulses 0.25 joule; energy density-360 J/cm2 per pulse; power on tissue-5W. The laser group was divided into three, receiving 20, 40 or 60 pulses, respectively. On light microscopy: in all the control group cases, large amount of residual pulp tissue was seen, it was diminished in some of the low energy group and was totally eradicated in the high energy group. This was confirmed by the scanning electron microscope (SEM) examination. The dentin tubuli were partly occluded with the low energy levels and completely with the high levels, as shown by the high-speed centrifuge dye penetration test and by the SEM tests.

  7. First proton transfer reaction to study 18F+p resonances of novae interest

    SciTech Connect

    Adekola, Aderemi S; Bardayan, Daniel W; Blackmon, Jeff C; Brune, C.; Chae, K. Y.; Domizioli, Carlo P; Greife, U.; Heinen, Z.; Hornish, M.; Jones, K. L.; Kozub, R. L.; Livesay, Jake; Ma, Zhanwen; Massey, T.; Moazen, Brian; Nesaraja, Caroline D; Pain, S. D.; ShrinerJr., J. F.; Smith, Nathan A; Smith, Michael Scott; Thomas, J. S.; Visser, D. W.; Voinov, A.

    2011-01-01

    The 18F(p,a)15O reaction is recognized as the predominant destruction mechanism of 18F in novae, and its rate is therefore important for understanding 18F production in nova outbursts. We have studied the properties of resonances in the 18F + p system using the proton-transfer reaction 18F(d, n) for the first time. We have observed fifteen 19Ne levels, five of which are below the proton threshold, including a subthreshold state at Ex = 6.289 MeV which has significant lp = 0 strength. The proton asymptotic normalization coefficient for this state and proton widths of states above the proton threshold, are extracted from angular distributions. The 18F(p,a)15O S-factor and reaction rate are re-evaluated, taking into account the subthreshold resonance and other new information determined in this experiment.

  8. The temporal evolution of sanukitoids in the Karelian Craton, Baltic Shield: an ion microprobe U Th Pb isotopic study of zircons

    NASA Astrophysics Data System (ADS)

    Bibikova, E. V.; Petrova, A.; Claesson, S.

    2005-01-01

    The U-Th-Pb isotopic systematics of zircons from six sanukitoid intrusions in the Karelian Craton has been investigated, using the secondary ion mass spectrometer (SIMS). Our results show that Karelian sanukitoids formed between 2745 and 2705 Ma ago and that there is an age difference of about 30 Ma between sanukitoids in the eastern and western Karelia. Results for intrusions made up of a number of magmatic phases show no internal age variation. In the east of the study region, zircons from a monzodiorite and two quartz monzonites from the Panozero pluton were dated at 2737±11, 2739±11, and 2741±8 Ma; in the Hautavaara pluton, a monzodiorite and a subalkaline granite were dated at 2743±8 and 2742±23 Ma, and a quartz diorite from the Elmus pluton gave an age of 2741±7 Ma. In addition, a lamprophyre dyke within the Sjargozero pluton gave an age of 2742±14 Ma. In the west, zircons from a quartz monzonite and a granodiorite in the Njuk intrusion gave ages of 2709±10 and 2716±11 Ma. In the Kurgelampi pluton, zircons from a diorite and two granodiorites were dated at 2707±9, 2719±6, and 2712±9 Ma, respectively. Zircons from the granodiorites and the alkaline granites contain older cores with 207Pb/ 206Pb ages greater than 2800 Ma. The absence of inherited zircons in the more mafic sanukitoids is attributed to their higher saturation levels for zirconium. Sanukitoid zircons have Th/U ratios above 0.5 and often higher, whereas nearby tonalite-tondhjemite-granodiorites (TTGs) have Th/U ratios below 0.5. Typically, tonalites are older than sanukitoids by more than 100 Ma and it is possible that tectonic processes associated with the collision of the Belomorian Mobile Belt provided the heat necessary to initiate the generation of the sanukitoid melts.

  9. [Histopathologic study of melanoma of the choroid after proton therapy].

    PubMed

    Devouassoux Shishe Boran, M; Grange, J D; Patricot, L M; Adeleine, P; Chauvel, P; Chiquet, C; Vitrey, D; Thivolet Béjui, F

    1997-07-01

    To evaluate irradiation effects on choroidal melanomas, histopathologic findings of 18 eyes whose primary treatment was enucleation were compared to 15 eyes enucleated after proton beam irradiation. Irradiated tumors showed more likely necrosis (p = 0.01) had balloon cells (p = 0.01), and inflammatory infiltrate (p = 0.05). In the irradiated group, the prevalence of tumor blood vessel damage was higher (p = 0.0002) and mitotic figures were fewer (p = 0.01). These findings suggest that proton beam irradiation damages tumor cells and alters the tumor's capacity for cellular reproduction. It damages blood vessels leading to tumor necrosis. It induces an inflammatory response of unknown effects. Radiosensitivity of choroidal melanomas cannot be assessed using conventional histologic methods. However, tumor necrosis, mitotic activity and rate of balloon cells can help to establish tumoral sensitivity to irradiation. PMID:9296578

  10. A laboratory and theoretical study of protonated carbon disulfide, HSCS+.

    PubMed

    McCarthy, M C; Thaddeus, P; Wilke, Jeremiah J; Schaefer, Henry F

    2009-06-21

    The rotational spectrum of protonated carbon disulfide, HSCS(+), has been detected in the centimeter-wave band in a molecular beam by Fourier transform microwave spectroscopy. Rotational and centrifugal distortion constants have been determined from ten transitions in the K(a)=0 ladder of the normal isotopic species, HS(13)CS(+), and DSCS(+). The present assignment agrees well with high-level coupled cluster calculations of the HSCS(+) structure, which, like earlier work, predict this isomer to be the ground state on the HCS(2) (+) potential energy surface; HCSS(+), an isomer with C(2v) symmetry, is predicted to lie more than 20 kcal/mol higher in energy. Other properties of HSCS(+) including its dipole moment, anharmonic vibrational frequencies, and infrared intensities have also been computed at the coupled cluster level of theory with large basis sets. Because carbon disulfide possesses a fairly large proton affinity, and because this nonpolar molecule may plausibly exist in astronomical sources, HSCS(+) is a good candidate for detection with radio telescopes in the submillimeter band where the stronger b-type transitions of this protonated cation are predicted to lie. PMID:19548724

  11. Design and characterization of a resonant triaxial microprobe

    NASA Astrophysics Data System (ADS)

    Goj, Boris; Dressler, Lothar; Hoffmann, Martin

    2015-12-01

    A new trend for tactile microprobes leads to oscillating microprobes in order to overcome the drawbacks resulting from high Hertzian stress and disturbing surface forces. Thin water films on the measurement surface result in the so-called sticking effect which causes measurement faults such as snap-back and false triggering. This leads to measurement errors and low measurement speeds. We present an innovative oscillating triaxial microprobe which safely avoids sticking in all Cartesian measurement directions. The system design as well as the characterization of the microprobe are presented in this work. The low number of coupling elements, the batch-capable design and the low contact forces are the key features of the microprobe.

  12. Beyond Gaussians: a study of single-spot modeling for scanning proton dose calculation

    NASA Astrophysics Data System (ADS)

    Li, Yupeng; Zhu, Ronald X.; Sahoo, Narayan; Anand, Aman; Zhang, Xiaodong

    2012-02-01

    Active spot scanning proton therapy is becoming increasingly adopted by proton therapy centers worldwide. Unlike passive-scattering proton therapy, active spot scanning proton therapy, especially intensity-modulated proton therapy, requires proper modeling of each scanning spot to ensure accurate computation of the total dose distribution contributed from a large number of spots. During commissioning of the spot scanning gantry at the Proton Therapy Center in Houston, it was observed that the long-range scattering protons in a medium may have been inadequately modeled for high-energy beams by a commercial treatment planning system, which could lead to incorrect prediction of field size effects on dose output. In this study, we developed a pencil beam algorithm for scanning proton dose calculation by focusing on properly modeling individual scanning spots. All modeling parameters required by the pencil beam algorithm can be generated based solely on a few sets of measured data. We demonstrated that low-dose halos in single-spot profiles in the medium could be adequately modeled with the addition of a modified Cauchy-Lorentz distribution function to a double-Gaussian function. The field size effects were accurately computed at all depths and field sizes for all energies, and good dose accuracy was also achieved for patient dose verification. The implementation of the proposed pencil beam algorithm also enabled us to study the importance of different modeling components and parameters at various beam energies. The results of this study may be helpful in improving dose calculation accuracy and simplifying beam commissioning and treatment planning processes for spot scanning proton therapy

  13. Beyond Gaussians: a study of single spot modeling for scanning proton dose calculation

    PubMed Central

    Li, Yupeng; Zhu, Ronald X.; Sahoo, Narayan; Anand, Aman; Zhang, Xiaodong

    2013-01-01

    Active spot scanning proton therapy is becoming increasingly adopted by proton therapy centers worldwide. Unlike passive-scattering proton therapy, active spot scanning proton therapy, especially intensity-modulated proton therapy, requires proper modeling of each scanning spot to ensure accurate computation of the total dose distribution contributed from a large number of spots. During commissioning of the spot scanning gantry at the Proton Therapy Center in Houston, it was observed that the long-range scattering protons in a medium may have been inadequately modeled for high-energy beams by a commercial treatment planning system, which could lead to incorrect prediction of field-size effects on dose output. In the present study, we developed a pencil-beam algorithm for scanning-proton dose calculation by focusing on properly modeling individual scanning spots. All modeling parameters required by the pencil-beam algorithm can be generated based solely on a few sets of measured data. We demonstrated that low-dose halos in single-spot profiles in the medium could be adequately modeled with the addition of a modified Cauchy-Lorentz distribution function to a double-Gaussian function. The field-size effects were accurately computed at all depths and field sizes for all energies, and good dose accuracy was also achieved for patient dose verification. The implementation of the proposed pencil beam algorithm also enabled us to study the importance of different modeling components and parameters at various beam energies. The results of this study may be helpful in improving dose calculation accuracy and simplifying beam commissioning and treatment planning processes for spot scanning proton therapy. PMID:22297324

  14. Experimental stand for studying the impact of laser-accelerated protons on biological objects

    NASA Astrophysics Data System (ADS)

    Burdonov, K. F.; Eremeev, A. A.; Ignatova, N. I.; Osmanov, R. R.; Sladkov, A. D.; Soloviev, A. A.; Starodubtsev, M. V.; Ginzburg, V. N.; Kuz'min, A. A.; Maslennikova, A. V.; Revet, G.; Sergeev, A. M.; Fuchs, J.; Khazanov, E. A.; Chen, S.; Shaykin, A. A.; Shaikin, I. A.; Yakovlev, I. V.

    2016-04-01

    An original experimental stand is presented, aimed at studying the impact of high-energy protons, produced by the laser-plasma interaction at a petawatt power level, on biological objects. In the course of pilot experiments with the energy of laser-accelerated protons up to 25 MeV, the possibility is demonstrated of transferring doses up to 10 Gy to the object of study in a single shot with the magnetic separation of protons from parasitic X-ray radiation and fast electrons. The technique of irradiating the cell culture HeLa Kyoto and measuring the fraction of survived cells is developed. The ways of optimising the parameters of proton beams and the suitable methods of their separation with respect to energy and transporting to the studied living objects are discussed. The construction of the stand is intended for the improvement of laser technologies for hadron therapy of malignant neoplasms.

  15. The electron microprobe as a metallographic tool

    NASA Technical Reports Server (NTRS)

    Goldstein, J. I.

    1974-01-01

    The electron microprobe (EMP) is shown to represent one of the most powerful techniques for the examination of the microstructure of materials. It is an electron optical instrument in which compositional and topographic information is obtained from regions smaller than 1 micron in diameter on a specimen. Photographs of compositional and topographic changes in 1-sq-mm to 20-sq-micron areas on various types of specimens can also be obtained. These photographs are strikingly similar to optical photomicrographs. Various signals measured in the EMP (X-rays, secondary electrons, backscattered electrons, etc.) are discussed, along with their resolution and the type of information they may help obtain. In addition to elemental analysis, solid state detecting and scanning techniques are reviewed. Various techniques extending the EMP instrument capabilities, such as deconvolution and soft X-ray analysis, are also described.

  16. Aerodynamics of the Mars Microprobe Entry Vehicles

    NASA Technical Reports Server (NTRS)

    Mitcheltree, R. A.; Moss, J. N.; Cheatwood, F. M.; Greene, F. A.; Braun, R. D.

    1997-01-01

    The selection of the unique aeroshell shape for the Mars Microprobes is discussed. A description of its aerodynamics in hypersonic rarefied, hypersonic continuum, supersonic and transonic flow regimes is then presented. This description is based on Direct Simulation Monte Carlo analyses in the rarefied-flow regime, thermochemical nonequilibrium Computational Fluid Dynamics in the hypersonic regime, existing wind tunnel data in the supersonic and transonic regime, additional computational work in the transonic regime, and finally, ballistic range data. The aeroshell is shown to possess the correct combination of aerodynamic stability and drag to convert the probe's initial tumbling attitude and high velocity at atmospheric-interface into the desired surface-impact orientation and velocity.

  17. Studies of Neutron and Proton Nuclear Activation in Low-Earth Orbit 2

    NASA Technical Reports Server (NTRS)

    Laird, C. E.

    1983-01-01

    The study of neutron and proton nuclear activation in low-Earth orbit reported in NASA CR-162051 has been continued with increasing emphasis given to primary and secondary neutron activation. The previously reported activation due to protons has been modified to include: (1) flux attenuation caused by all inelastic reactions; (2) the modification of the proton flux distribution caused by sample covering material; and (3) the activation of the sample as a function of the distance into the sample from the surface of incidence. A method has been developed for including the effects on the activation of the finite width and length of the samples. The reactant product spectra produced by proton-induced reactions has been studied. Cross sections needed for neutron induced reactions leading to long-lived (half-life 1 day) radioisotopes have been identified and, in some cases, compiled.

  18. Unusual energy dispersion at the proton isotropy boundary: a statistical study

    NASA Astrophysics Data System (ADS)

    Chernyaeva, Sonya; Angelopoulos, Vassilis; Sergeev, Viktor; Chernyaev, Ivan

    The regular appearance of equatorward boundary of the isotropic proton precipitation (isotropy boundary, IB) is interpreted as a manifestation of the boundary between adiabatic and non-adiabatic particle motion regimes. Accordingly, the energy dependence of IB latitude (energy dispersion, with lower latitude IB observed for higher energy protons in case of normal dispersion) carries the information about the real magnetic field gradients (or, sporadic appearance of other scattering mechanism, in case of anomalous dispersion). In this study we investigate statistically the IB energy dispersion of the >30 and >80 keV energetic protons using data from low-altitude polar satellites NOAA-19 and -18 in September 2009, when two spacecraft follow each other along the same orbit. We found that the events with normal dispersion at proton energies of 30 to 80 keV protons constitute less than 20% of the total number of events (regardless of geomagnetic activity). In other cases (80%) we see either the coincidence of the proton IB at different energies (within 0.2(°) ), or the precipitation pattern is complicated by the presence of isolated precipitation structures equatorward of the IB. In small amount of cases the anomalous (inverse) energy dispersion was also observed, suggesting the presence of different precipitation mechanisms. To help discriminate between current sheet scattering and other mechanisms we also obtained the average relationship between empirical ratios of trapped and precipitated proton fluxes at different energies near the IB for cases of normal dispersion. The near coincidence of the proton IBs can be observed in the case of sharp magnetic field Bz gradients (Bz jumps), whose amplitude should be about 60% of the Bz background value. Their existence is tested by considering magnetic field observations at radial passes of THEMIS spacecraft near the IB observation meridian in the near magnetosphere, supported by adaptive modeling and other relevant

  19. Theoretical and computational studies of renewable energy materials: Room temperature ionic liquids and proton exchange membranes

    NASA Astrophysics Data System (ADS)

    Feng, Shulu

    2011-12-01

    Two kinds of renewable energy materials, room temperature ionic liquids (RTILs) and proton exchange membranes (PEMs), especially Nafion, are studied by computational and theoretical approaches. The ultimate purpose of the present research is to design novel materials to meet the future energy demands. To elucidate the effect of alkyl side chain length and anion on the structure and dynamics of the mixtures, molecular dynamics (MD) simulations of three RTILs/water mixtures at various water mole fractions: 1-butyl-3-methylimidazolium (BMIM+)/BF4-, 1-octyl-3-methylimidazolium (OMIM+)/BF4-, and OMIM +/Cl- are performed. Replacing the BMIM + cation with OMIM+ results in stronger aggregation of the cations as well as a slower diffusion of the anions, and replacing the BF4- anion with Cl- alters the water distribution at low water mole fractions and slows diffusion of the mixtures. Potential experimental manifestations of these behaviors in both cases are provided. Proton solvation properties and transport mechanisms are studied in hydrated Nafion, by using the self-consistent multistate empirical valence bond (SCI-MS-EVB) method. It is found that by stabilizing a more Zundel-like (H5O 2+) structure in the first solvation shells, the solvation of excess protons, as well as the proton hydration structure are both influenced by the sulfonate groups. Hydrate proton-related hydrogen bond networks are observed to be more stable than those with water alone. In order to characterize the nature of the proton transport (PT), diffusive motion, Arrhenius activation energies, and transport pathways are calculated and analyzed. Analysis of diffusive motion suggests that (1) a proton-hopping mechanism dominates the proton transport for the studied water loading levels and (2) there is an obvious degree of anti-correlation between the proton hopping and the vehicular transport. The activation energy drops rapidly with an increasing water content when the water loading level is smaller

  20. Analysis of biological materials using a nuclear microprobe

    NASA Astrophysics Data System (ADS)

    Mulware, Stephen Juma

    The use of nuclear microprobe techniques including: Particle induced x-ray emission (PIXE) and Rutherford backscattering spectrometry (RBS) for elemental analysis and quantitative elemental imaging of biological samples is especially useful in biological and biomedical research because of its high sensitivity for physiologically important trace elements or toxic heavy metals. The nuclear microprobe of the Ion Beam Modification and Analysis Laboratory (IBMAL) has been used to study the enhancement in metal uptake of two different plants. The roots of corn (Zea mays) have been analyzed to study the enhancement of iron uptake by adding Fe (II) or Fe(III) of different concentrations to the germinating medium of the seeds. The Fe uptake enhancement effect produced by lacing the germinating medium with carbon nanotubes has also been investigated. The aim of this investigation is to ensure not only high crop yield but also Fe-rich food products especially from calcareous soil which covers 30% of world's agricultural land. The result will help reduce iron deficiency anemia, which has been identified as the leading nutritional disorder especially in developing countries by the World Health Organization. For the second plant, Mexican marigold (Tagetes erecta ), the effect of an arbuscular mycorrhizal fungi (Glomus intraradices ) for the improvement of lead phytoremediation of lead contaminated soil has been investigated. Phytoremediation provides an environmentally safe technique of removing toxic heavy metals (like lead), which can find their way into human food, from lands contaminated by human activities like mining or by natural disasters like earthquakes. The roots of Mexican marigold have been analyzed to study the role of arbuscular mycorrhizal fungi in enhancement of lead uptake from the contaminated rhizosphere.

  1. ATS-6 - Synchronous orbit trapped radiation studies with an electron-proton spectrometer

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; Swanson, R. L.; Winckler, J. R.; Erickson, K. N.

    1975-01-01

    The paper discusses the University of Minnesota experiment on ATS-6 designed to study the origin and dynamics of high-energy electrons and protons in the outer radiation belt and in the near-earth plasma sheet. The experiment consists of two nearly identical detector assemblies, each of which is a magnetic spectrometer containing four gold-silicon surface barrier detectors. The instrument provides a clean separation between protons and electrons by the combination of pulse height analysis and magnetic deflection.

  2. Ion microprobe mass spectrometry using sputtering atomization and resonance ionization

    SciTech Connect

    Donohue, D.L.; Christie, W.H.; Goeringer, D.E.

    1985-01-01

    Resonance ionization mass spectrometry (RIMS) has recently been developed into a useful technique for isotope ratio measurements. Studies performed in our laboratory (1-6) have been reported for a variety of elements using thermal vaporization sources to produce the atom reservoir for laser-induced resonance ionization. A commercial ion microprobe mass analyzer (IMMA) has been interfaced with a tunable pulsed dye laser for carrying out resonance ionization mass spectrometry of sputtered atoms. The IMMA instrument has many advantages for this work, including a micro-focused primary ion beam (2 ..mu..m in diameter) of selected mass, complete sample manipulation and viewing capability, and a double-focusing mass spectrometer for separation and detection of the secondary or laser-generated ions. Data were obtained demonstrating the number and type of ions formed along with optical spectral information showing the wavelengths at which resonance ionization occurs. 7 refs.

  3. Micro Electron MicroProbe and Sample Analyzer

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Bearman, Gregory; Douglas, Susanne; Bronikowski, Michael; Urgiles, Eduardo; Kowalczyk, Robert; Bryson, Charles

    2009-01-01

    A proposed, low-power, backpack-sized instrument, denoted the micro electron microprobe and sample analyzer (MEMSA), would serve as a means of rapidly performing high-resolution microscopy and energy-dispersive x-ray spectroscopy (EDX) of soil, dust, and rock particles in the field. The MEMSA would be similar to an environmental scanning electron microscope (ESEM) but would be much smaller and designed specifically for field use in studying effects of geological alteration at the micrometer scale. Like an ESEM, the MEMSA could be used to examine uncoated, electrically nonconductive specimens. In addition to the difference in size, other significant differences between the MEMSA and an ESEM lie in the mode of scanning and the nature of the electron source.

  4. Studies of Zinc Oxide Nanocrystals: Quantification of Capping Ligands and the Coupling of Protons and Electrons

    NASA Astrophysics Data System (ADS)

    Valdez, Carolyn N.

    per NC (max) reaches a maximum, beyond which the addition of more acid has no effect. This max varies with the NC radius with an r3 dependence, so the density of electrons (max) is constant over a range of NC sizes. The approximately 1:1 relationship of with protons per NC, and the dramatic dependence of max on the nature of the cation (H+ vs. MCp*2+) suggest that the protons intercalate into the NCs under these conditions. These studies illustrate the strong coupling between protons and electrons in ZnO NCs and show that proton activity is a key parameter in nanomaterial energetics.

  5. Optimized Structures and Proton Affinities of Fluorinated Dimethyl Ethers: An Ab Initio Study

    NASA Technical Reports Server (NTRS)

    Orgel, Victoria B.; Ball, David W.; Zehe, Michael J.

    1996-01-01

    Ab initio methods have been used to investigate the proton affinity and the geometry changes upon protonation for the molecules (CH3)2O, (CH2F)2O, (CHF2)2O, and (CF3)2O. Geometry optimizations were performed at the MP2/3-2 I G level, and the resulting geometries were used for single-point energy MP2/6-31G calculations. The proton affinity calculated for (CH3)2O was 7 Kjoule/mole from the experimental value, within the desired variance of +/- 8Kjoule/mole for G2 theory, suggesting that the methodology used in this study is adequate for energy difference considerations. For (CF3)20, the calculated proton affinity of 602 Kjoule/mole suggests that perfluorinated ether molecules do not act as Lewis bases under normal circumstances; e.g. degradation of commercial lubricants in tribological applications.

  6. A fluorescence study of isofagomine protonation in β-glucosidase.

    PubMed

    Lindbäck, Emil; Laursen, Bo Wegge; Poulsen, Jens Christian Navarro; Kilså, Kristine; Pedersen, Christian Marcus; Bols, Mikael

    2015-06-21

    N-(10-Chloro-9-anthracenemethyl)isofagomine 5 and N-(10-chloro-9-anthracenemethyl)-1-deoxynojirimycin 6 were prepared, and their inhibition of almond β-glucosidase was measured. The isofagomine derivative 5 was found to be a potent inhibitor, while the 1-deoxynojirimycin derivative 6 displayed no inhibition at the concentrations investigated. Fluorescence spectroscopy of 5 with almond β-glucosidase at different pH values showed that the inhibitor nitrogen is not protonated when bound to the enzyme. Analysis of pH inhibition data confirmed that 5 binds as the amine to the enzyme's unprotonated dicarboxylate form. This is a radically different binding mode than has been observed with isofagomine and other iminosugars in the literature. PMID:25978843

  7. Experimental study of proton beam halo in mismatched beams

    SciTech Connect

    Allen, C. K.; Chan, K. D.; Colestock, P. L. ,; Garnett, R. W.; Gilpatrick, J. D.; Qiang, J.; Lysenko, W. P.; Smith, H. V.; Schneider, J. D.; Sheffield, R. L.; Wangler, Thomas P.,; Schulze, M. E.; Crandall, K. R.

    2002-01-01

    We report measurements of transverse beam-halo formation in mismatched proton beams in a 52-quadrupole FODO-transport channel following the 6.7 MeV RFQ at the Low-Energy Demonstration Accelerator (LEDA) at Los Alamos. Beam profiles in both transverse planes were measured using a new diagnostic device that consists of a movable carbon filament for measurement of the beam core, and scraper plates for measurement of the outer part of the distributions. The initial results indicate a surprisingly strong growth rate of the rms emittance even for the modest space-charge tune depressions of the experiment. Our results are consistent with the complete transfer of free energy of the mismatched beams into emittance growth within 10 envelope oscillations for both the breathing and the quadrupole modes.

  8. A study on analytic parametrizations for proton-proton cross-sections and asymptotia

    NASA Astrophysics Data System (ADS)

    Menon, M. J.; Silva, P. V. R. G.

    2013-12-01

    A comparative study on some representative parametrizations for the total and elastic cross-sections as a function of energy is presented. The dataset comprises pp and \\bar{p}p scattering in the c.m. energy interval 5 GeV-8 TeV. The parametrization for the total cross-section at low and intermediate energies follows the usual reggeonic structure (non-degenerate trajectories). For the leading high-energy pomeron contribution, we consider three distinct analytic parametrizations: either a power (P) law, or a log-squared (L2) law or a log-raised-to-γ (Lγ) law, where the exponent γ is treated as a real free fit parameter. The parametrizations are also extended to fit the elastic (integrated) cross-section data in the same energy interval. Our main conclusions are the following: (1) the data reductions with the logarithmic laws show strong dependence on the unknown energy scale involved, which is treated here either as a free parameter or fixed at the energy threshold; (2) the fit results with the P law, the L2 law (free scale) and the Lγ law (fixed scale and exponent γ above 2) are all consistent within their uncertainties and with the experimental data up to 7 TeV, but they partially underestimate the high-precision TOTEM measurement at 8 TeV (3) once compared with these results, the L2 law with fixed scale is less consistent with the data and, in the case of a free scale, this pomeron contribution decreases as the energy increases below the scale factor (which lies above the energy cutoff); (4) in all cases investigated, the predictions for the asymptotic ratio between the elastic and total cross-sections, within the uncertainties, do not exceed the value 0.430 (therefore, below the black-disc limit) and the results favor rational limits between 1/3 and 2/5. We are led to conclude that the rise of the hadronic cross-sections at the highest energies still constitutes an open problem, demanding further and detailed investigation.

  9. A noncontact thermal microprobe for local thermal conductivity measurement.

    PubMed

    Zhang, Yanliang; Castillo, Eduardo E; Mehta, Rutvik J; Ramanath, Ganpati; Borca-Tasciuc, Theodorian

    2011-02-01

    We demonstrate a noncontact thermal microprobe technique for measuring the thermal conductivity κ with ∼3 μm lateral spatial resolution by exploiting quasiballistic air conduction across a 10-100 nm air gap between a joule-heated microprobe and the sample. The thermal conductivity is extracted from the measured effective thermal resistance of the microprobe and the tip-sample thermal contact conductance and radius in the quasiballistic regime determined by calibration on reference samples using a heat transfer model. Our κ values are within 5%-10% of that measured by standard steady-state methods and theoretical predictions for nanostructured bulk and thin film assemblies of pnictogen chalcogenides. Noncontact thermal microprobing demonstrated here mitigates the strong dependence of tip-sample heat transfer on sample surface chemistry and topography inherent in contact methods, and allows the thermal characterization of a wide range of nanomaterials. PMID:21361625

  10. A noncontact thermal microprobe for local thermal conductivity measurement

    NASA Astrophysics Data System (ADS)

    Zhang, Yanliang; Castillo, Eduardo E.; Mehta, Rutvik J.; Ramanath, Ganpati; Borca-Tasciuc, Theodorian

    2011-02-01

    We demonstrate a noncontact thermal microprobe technique for measuring the thermal conductivity κ with ˜3 μm lateral spatial resolution by exploiting quasiballistic air conduction across a 10-100 nm air gap between a joule-heated microprobe and the sample. The thermal conductivity is extracted from the measured effective thermal resistance of the microprobe and the tip-sample thermal contact conductance and radius in the quasiballistic regime determined by calibration on reference samples using a heat transfer model. Our κ values are within 5%-10% of that measured by standard steady-state methods and theoretical predictions for nanostructured bulk and thin film assemblies of pnictogen chalcogenides. Noncontact thermal microprobing demonstrated here mitigates the strong dependence of tip-sample heat transfer on sample surface chemistry and topography inherent in contact methods, and allows the thermal characterization of a wide range of nanomaterials.

  11. Stand-alone microprobe at Livermore

    SciTech Connect

    Antolak, A J; Bench, G S; Brown, T A; Frantz, B R; Grant, P G; Morse, D H; Roberts, M L

    1998-10-02

    Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories/California have jointly constructed a new stand-alone microprobe facility. Although the facility was built to develop a method to rapidly locate and determine elemental concentrations of micron scale particulates on various media using PIXE, the facility has found numerous applications in biology and materials science. The facility is located at LLNL and uses a General Ionex Corporation Model 358 duoplasmatron negative ion source, a National Electrostatics Corporation 5SDH-2 tandem accelerator, and an Oxford triplet lens. Features of the system include complete computer control of the beam transport using LabVIEWTM for Macintosh, computer controlled beam collimating and divergence limiting slits, automated sample positioning to micron resolution, and video optics for beam positioning and sample observation. Data collection is accomplished with the simultaneous use of as many as four EG&G Ortec IGLET-XTM X-Ray detectors, digital amplifiers made by X-Ray Instruments and Associates (XIA), and LabVIEWTM for Macintosh acquisition software.

  12. Aerothermal Heating Predictions for Mars Microprobe

    NASA Technical Reports Server (NTRS)

    Mitcheltree, R. A.; DiFulvio, M.; Horvath, T. J.; Braun, R. D.

    1998-01-01

    A combination of computational predictions and experimental measurements of the aerothermal heating expected on the two Mars Microprobes during their entry to Mars are presented. The maximum, non-ablating, heating rate at the vehicle's stagnation point (at alpha = 0 degrees) is predicted for an undershoot trajectory to be 194 Watts per square centimeters with associated stagnation point pressure of 0.064 atm. Maximum stagnation point pressure occurs later during the undershoot trajectory and is 0.094 atm. From computations at seven overshoot-trajectory points, the maximum heat load expected at the stagnation point is near 8800 Joules per square centimeter. Heat rates and heat loads on the vehicle's afterbody are much lower than the forebody. At zero degree angle-of-attack, heating over much of the hemi-spherical afterbody is predicted to be less than 2 percent of the stagnation point value. Good qualitative agreement is demonstrated for forebody and afterbody heating between CFD calculations at Mars entry conditions and experimental thermographic phosphor measurements from the Langley 20-Inch Mach 6 Air Tunnel. A novel approach which incorporates six degree-of-freedom trajectory simulations to perform a statistical estimate of the effect of angle-of-attack, and other off-nominal conditions, on heating is included.

  13. Wavelength dispersive analysis with the synchrotron x ray fluorescence microprobe

    NASA Technical Reports Server (NTRS)

    Rivers, M. L.; Thorn, K. S.; Sutton, S. R.; Jones, K. W.; Bajt, S.

    1993-01-01

    A wavelength dispersive spectrometer (WDS) was tested on the synchrotron x ray fluorescence microprobe at Brookhaven National Laboratory. Compared to WDS spectra using an electron microprobe, the synchrotron WDS spectra have much better sensitivity and, due to the absence of bremsstrahlung radiation, lower backgrounds. The WDS spectrometer was successfully used to resolve REE L fluorescence spectra from standard glasses and transition metal K fluorescence spectra from kamacite.

  14. Study of new proton conducting glasses for fuel cells

    NASA Astrophysics Data System (ADS)

    Tiple, S. R.; Deshpande, V. K.

    2015-08-01

    The glasses in the series (35-x) BaO:65 P2O5:x (NH4)2SO4 are synthesized and characterized by Tg, CTE, density and electrical conductivity measurements. The decrease in density and Tg is observed with addition of (NH4)2SO4. The increase in CTE compliments the observed variation in Tg. The protonic conductivity increases with addition of (NH4)2SO4 up to 7.5 mol% and decreases beyond this composition. The increase in the ratio of O/P, which in turn, creates more non-bridging oxygens, enhances the conductivity. Further, sulfur is mainly incorporated in sulfophosphate glasses as isolated SO42- group which also results in increase in conductivity. The glass with maximum conductivity [7.5(NH4)2SO4:27.5BaO:65 P2O5] is used to fabricate a fuel cell. It gives the power density of 12.43 μW/cm2. The power density of the fuel cell in the present work at room temperature is higher than that reported in literature at 473 K. The fuel cell has a potential of giving higher power density at higher temperature of 423 K.

  15. Proton transport in triflic acid pentahydrate studied via ab initio path integral molecular dynamics.

    PubMed

    Hayes, Robin L; Paddison, Stephen J; Tuckerman, Mark E

    2011-06-16

    Trifluoromethanesulfonic acid hydrates provide a well-defined system to study proton dissociation and transport in perfluorosulfonic acid membranes, typically used as the electrolyte in hydrogen fuel cells, in the limit of minimal water. The triflic acid pentahydrate crystal (CF(3)SO(3)H·5H(2)O) is sufficiently aqueous that it contains an extended three-dimensional water network. Despite it being extended, however, long-range proton transport along the network is structurally unfavorable and would require considerable rearrangement. Nevertheless, the triflic acid pentahydrate crystal system can provide a clear picture of the preferred locations of local protonic defects in the water network, which provides insights about related structures in the disordered, low-hydration environment of perfluorosulfonic acid membranes. Ab initio molecular dynamics simulations reveal that the proton defect is most likely to transfer to the closest water that has the expected presolvation and only contains water in its first solvation shell. Unlike the tetrahydrate of triflic acid (CF(3)SO(3)H·4H(2)O), there is no evidence of the proton preferentially transferring to a water molecule bridging two of the sulfonate groups. However, this could be an artifact of the crystal structure since the only such water molecule is separated from the proton by long O-O distances. Hydrogen bonding criteria, using the two-dimensional potential of mean force, are extracted. Radial distribution functions, free energy profiles, radii of gyration, and the root-mean-square displacement computed from ab initio path integral molecular dynamics simulations reveal that quantum effects do significantly extend the size of the protonic defect and increase the frequency of proton transfer events by nearly 15%. The calculated IR spectra confirm that the dominant protonic defect mostly exists as an Eigen cation but contains some Zundel ion characteristics. Chain lengths and ring sizes determined from the

  16. Proton Transport

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    The transport of protons across membranes is an essential process for both bioenergetics of modern cells and the origins of cellular life. All living systems make use of proton gradients across cell walls to convert environmental energy into a high-energy chemical compound, adenosine triphosphate (ATP), synthesized from adenosine diphosphate. ATP, in turn, is used as a source of energy to drive many cellular reactions. The ubiquity of this process in biology suggests that even the earliest cellular systems were relying on proton gradient for harvesting environmental energy needed to support their survival and growth. In contemporary cells, proton transfer is assisted by large, complex proteins embedded in membranes. The issue addressed in this Study was: how the same process can be accomplished with the aid of similar but much simpler molecules that could have existed in the protobiological milieu? The model system used in the study contained a bilayer membrane made of phospholipid, dimyristoylphosphatidylcholine (DMPC) which is a good model of the biological membranes forming cellular boundaries. Both sides of the bilayer were surrounded by water which simulated the environment inside and outside the cell. Embedded in the membrane was a fragment of the Influenza-A M$_2$ protein and enough sodium counterions to maintain system neutrality. This protein has been shown to exhibit remarkably high rates of proton transport and, therefore, is an excellent model to study the formation of proton gradients across membranes. The Influenza M$_2$ protein is 97 amino acids in length, but a fragment 25 amino acids long. which contains a transmembrane domain of 19 amino acids flanked by three amino acids on each side. is sufficient to transport protons. Four identical protein fragments, each folded into a helix, aggregate to form small channels spanning the membrane. Protons are conducted through a narrow pore in the middle of the channel in response to applied voltage. This

  17. SU-E-T-304: Study of Secondary Neutrons From Uniform Scanning Proton Beams

    SciTech Connect

    Islam, M; Zheng, Y; Benton, E

    2014-06-01

    Purpose: Secondary neutrons are unwanted byproducts from proton therapy and exposure from secondary radiation during treatment could increase risk of developing a secondary cancer later in a patient's lifetime. The purpose of this study is to investigate secondary neutrons from uniform scanning proton beams under various beam conditions using both measurements and Monte Carlo simulations. Methods: CR-39 Plastic Track Nuclear Detectors (PNTD) were used for the measurement. CR-39 PNTD has tissue like sensitivity to the secondary neutrons but insensitive to the therapeutic protons. In this study, we devised two experimental conditions: a) hollow-phantom; phantom is bored with a hollow cylinder along the direction of the beam so that the primary proton passes through the phantom without interacting with the phantom material, b) cylindrical-phantom; a solid cylinder of diameter close to the beam diameter is placed along the beam path. CR-39 PNTDs were placed laterally inside a 60X20X35 cm3 phantom (hollow-phantom) and in air (cylindrical-phantom) at various angles with respect to the primary beam axis. We studied for three different proton energies (78 MeV, 162 MeV and 226 MeV), using a 4 cm modulation width and 5cm diameter brass aperture for the entire experiment and simulation. A comparison of the experiment was performed using the Monte Carlo code FLUKA. Results: The measured secondary neutron dose equivalent per therapeutic primary proton dose (H/D) ranges from 2.1 ± 0.2 to 25.42 ± 2.3 mSv/Gy for the hollow phantom study, and 2.7 ± 0.3 to 46.4 ± 3.4 mSv/Gy for the cylindrical phantom study. Monte Carlo simulations predicated neutron dose equivalent from measurements within a factor of 5. Conclusion: The study suggests that the production of external neutrons is significantly higher than the production of internal neutrons.

  18. Excess protons in water-acetone mixtures. II. A conductivity study.

    PubMed

    Semino, Rocío; Longinotti, M Paula

    2013-10-28

    In the present work we complement a previous simulation study [R. Semino and D. Laria, J. Chem. Phys. 136, 194503 (2012)] on the disruption of the proton transfer mechanism in water by the addition of an aprotic solvent, such as acetone. We provide experimental measurements of the mobility of protons in aqueous-acetone mixtures in a wide composition range, for water molar fractions, xw, between 0.05 and 1.00. Furthermore, new molecular dynamics simulation results are presented for rich acetone mixtures, which provide further insight into the proton transport mechanism in water-non-protic solvent mixtures. The proton mobility was analyzed between xw 0.05 and 1.00 and compared to molecular dynamics simulation data. Results show two qualitative changes in the proton transport composition dependence at xw ∼ 0.25 and 0.8. At xw < 0.25 the ratio of the infinite dilution molar conductivities of HCl and LiCl, Λ(0)(HCl).Λ(0)(LiCl)(-1), is approximately constant and equal to one, since the proton diffusion is vehicular and equal to that of Li(+). At xw ∼ 0.25, proton mobility starts to differ from that of Li(+) indicating that above this concentration the Grotthuss transport mechanism starts to be possible. Molecular dynamics simulation results showed that at this threshold concentration the probability of interconversion between two Eigen structures starts to be non-negligible. At xw ∼ 0.8, the infinite molar conductivity of HCl concentration dependence qualitatively changes. This result is in excellent agreement with the analysis presented in the previous simulation work and it has been ascribed to the interchange of water and acetone molecules in the second solvation shell of the hydronium ion. PMID:24182052

  19. Benchmark Study of the SCC-DFTB Approach for a Biomolecular Proton Channel

    PubMed Central

    Liang, Ruibin; Swanson, Jessica M. J.; Voth, Gregory A.

    2014-01-01

    The self-consistent charge density functional tight binding (SCC-DFTB) method has been increasingly applied to study proton transport (PT) in biological environments. However, recent studies revealing some significant limitations of SCC-DFTB for proton and hydroxide solvation and transport in bulk aqueous systems call into question its accuracy for simulating PT in biological systems. The current work benchmarks the SCC-DFTB/MM method against more accurate DFT/MM by simulating PT in a synthetic leucine-serine channel (LS2), which emulates the structure and function of biomolecular proton channels. It is observed that SCC-DFTB/MM produces over-coordinated and less structured pore water, an over-coordinated excess proton, weak hydrogen bonds around the excess proton charge defect and qualitatively different PT dynamics. Similar issues are demonstrated for PT in a carbon nanotube, indicating that the inaccuracies found for SCC-DFTB are not due to the point charge based QM/MM electrostatic coupling scheme, but rather to the approximations of the semiempirical method itself. The results presented in this work highlight the limitations of the present form of the SCC-DFTB/MM approach for simulating PT processes in biological protein or channel-like environments, while providing benchmark results that may lead to an improvement of the underlying method. PMID:25104919

  20. Molecular dynamics study of proton binding to silica surfaces

    SciTech Connect

    Rustad, J.R.; Wasserman, E.; Felmy, A.R.; Wilke, C.

    1998-02-01

    Molecular statics calculations on gas-phase and solvated clusters and on gas-phase and solvated slabs representing aqueous species and surfaces were applied to investigate acid/base reactions on silica surfaces. The gas-phase approach, which was previously applied to goethite, predicts a surface pK{sub a} of 8.5 for the reaction > SiOH {yields} > SiO{sup {minus}} + H{sup +} which is in good agreement with estimates based on potentiometric titration. However, the model gives an unrealistically large pK{sub a} for the reaction > SiOH{sub 2}{sup +} {yields} > SiOH + H{sup +}. The model dependence of this result was checked by using two different types of interaction potentials, one based on quantum mechanical calculations on H{sub 4}SiO{sub 4} clusters, and another empirical model fitted to the structure and elastic properties of {alpha}-quartz. Because these models gave similar results, the authors hypothesize that the failure of the gas-phase models is due to intrinsic solvation effects not accounted for by previously developed correlations. They tested this idea by carrying out energy minimization calculations on gas-phase clusters with one hydration shell as well as molecular dynamics simulations on fully-solvated H{sub 5}SiO{sub 4}{sup +} and a fully solvated (0001) surface of {beta}-quartz. Though the authors are unable to establish a quantitative measure of the pK{sub a} of SiOH{sub 2} groups, the solvated systems do indicate that SiOH groups do not protonate in any of the solvated models.

  1. Study of the Polarization Deterioration During Physics Stores in RHIC Polarized Proton Runs

    NASA Astrophysics Data System (ADS)

    Duan, Z.; Qin, Q.; Bai, M.; Roser, T.

    2016-02-01

    As the only high energy polarized proton collider in the world, the Relativistic Heavy Ion Collider (RHIC) has achieved a great success in colliding polarized proton beams up to 255GeV per beam energy with over 50% average store polarizations for spin physics studies. With the help of Siberian snakes as well as outstanding beam control during the acceleration, polarization loss during acceleration up to 100 GeV is negligible. However, about 10% polarization loss was observed between acceleration from 100 GeV to 255 GeV. In addition, a mild polarization deterioration during long store for physics data taking was also observed. In this paper, studies in understanding the store depolarizing mechanism is reported, including the analysis of polarization deterioration data based on the past couple of RHIC polarized proton runs.

  2. Proton NMR study of the state of water in fibrin gels, plasma, and blood clots

    SciTech Connect

    Blinc, A.; Lahajnar, G.; Blinc, R.; Zidansek, A.; Sepe, A. )

    1990-04-01

    A proton NMR relaxation and pulsed field gradient self-diffusion study of water in fibrin gels, plasma, and blood clots has been performed with special emphasis on the effect of the sol-gel and shrinkage transitions. Deuteron NMR in fibrin gels was also studied to supplement the proton data. It is shown that a measurement of the water proton or deuteron T1/T2 ratio allows for a determination of the bound water fraction in all these systems. The change in the T1/T2 ratio at the shrinkage transition further allows for a determination of the surface fractal dimension of the gel if the change in the volume of the gel is known. The self-diffusion coefficient of water in these systems, which determines the transport properties of the gel, is found to be proportional to the free water fraction in both the nonshrunken and shrunken state.

  3. Studies of neutron and proton nuclear activation in low-Earth orbit

    NASA Technical Reports Server (NTRS)

    Laird, C. E.

    1982-01-01

    The expected induced radioactivity of experimental material in low Earth orbit was studied for characteristics of activating particles such as cosmic rays, high energy Earth albedo neutrons, trapped protons, and secondary protons and neutrons. The activation cross sections for the production of long lived radioisotopes and other existing nuclear data appropriate to the study of these reactions were compiled. Computer codes which are required to calculate the expected activation of orbited materials were developed. The decreased computer code used to predict the activation of trapped protons of materials placed in the expected orbits of LDEF and Spacelab II. Techniques for unfolding the fluxes of activating particles from the measured activation of orbited materials are examined.

  4. Theoretical study of the structures of flavin in different oxidation and protonation states

    SciTech Connect

    Zheng, Y.J.; Ornstein, R.L.

    1996-10-02

    Ab initio molecular orbital theory was used to investigate the structure of flavin in different oxidation and protonation states using lumiflavin as a model compound. According to our study. oxidized flavin is planar no matter what its protonation state or whether it participates in hydrogen bonding. The structures of flavin semiquinone radicals are planar or very close to planar, but the reduced flavin H{sub 3}Fl{sub red} (9) is bent with a ring puckering angle of 27.3{degree} along the N5 and N10 axis. The calculations indicate that N1 is the site of protonation for oxidized flavin, which is in agreement with several crystallographic studies. The calculated spin density distribution for flavin semiquinone radicals is also consistent with experimental results. Electrostatic potential derived charges at the RHF/6-31G{sup *} level of theory are also provided for both oxidized and reduced flavins. 34 refs., 4 figs., 5 tabs.

  5. Applications of synchrotron x-ray fluorescence microprobe techniques to photochromic materials

    SciTech Connect

    Perry, D.L.

    1996-12-31

    Applications of synchrotron x-ray fluorescence microprobe techniques to photochromic materials are presented regarding dopant metal ions in the crystal matrices. Types of samples that are amenable to the technique will be discussed, along with sample format and experimental conditions. The chemical information that one can obtain from samples will be presented, and examples of copant contaminant studies in crystals will be given. New types of samples that are possible to study using this technique will be presented.

  6. Feasibility study of using statistical process control to customized quality assurance in proton therapy

    SciTech Connect

    Rah, Jeong-Eun; Oh, Do Hoon; Shin, Dongho; Kim, Tae Hyun; Kim, Gwe-Ya

    2014-09-15

    Purpose: To evaluate and improve the reliability of proton quality assurance (QA) processes and, to provide an optimal customized tolerance level using the statistical process control (SPC) methodology. Methods: The authors investigated the consistency check of dose per monitor unit (D/MU) and range in proton beams to see whether it was within the tolerance level of the daily QA process. This study analyzed the difference between the measured and calculated ranges along the central axis to improve the patient-specific QA process in proton beams by using process capability indices. Results: The authors established a customized tolerance level of ±2% for D/MU and ±0.5 mm for beam range in the daily proton QA process. In the authors’ analysis of the process capability indices, the patient-specific range measurements were capable of a specification limit of ±2% in clinical plans. Conclusions: SPC methodology is a useful tool for customizing the optimal QA tolerance levels and improving the quality of proton machine maintenance, treatment delivery, and ultimately patient safety.

  7. Impact of the material composition on proton range variation - A Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Wu, S. W.; Tung, C. J.; Lee, C. C.; Fan, K. H.; Huang, H. C.; Chao, T. C.

    2015-11-01

    In this study, we used the Geant4 toolkit to demonstrate the impacts of the material composition of tissues on proton range variation. Bragg curves of different materials subjected to a 250 MeV mono-energy proton beam were simulated and compared. These simulated materials included adipose, heart, brain, cartilage, cortical bone and water. The results showed that there was significant proton range deviation between Bragg curves, especially for cortical bone. The R50 values for a 250 MeV proton beam were approximately 39.55 cm, 35.52 cm, 37.00 cm, 36.51 cm, 36.72 cm, 22.53 cm, and 38.52 cm in the phantoms that were composed completely of adipose, cartilage, tissue, heart, brain, cortical bone, and water, respectively. Mass density and electron density were used to scale the proton range for each material; electron density provided better range scaling. In addition, a similar comparison was performed by artificially setting all material density to 1.0 g/cm3 to evaluate the range deviation due to chemical components alone. Tissue heterogeneity effects due to density variation were more significant, and less significant for chemical composition variation unless the Z/A was very different.

  8. Thermodynamic Study on the Protonation Reactions of Glyphosate in Aqueous Solution: Potentiometry, Calorimetry and NMR spectroscopy.

    PubMed

    Liu, Bijun; Dong, Lan; Yu, Qianhong; Li, Xingliang; Wu, Fengchang; Tan, Zhaoyi; Luo, Shunzhong

    2016-03-10

    Glyphosate [N-(phosphonomethyl)glycine] has been described as the ideal herbicide because of its unique properties. There is some conflicting information concerning the structures and conformations involved in the protonation process of glyphosate. Protonation may influence the chemical and physical properties of glyphosate, modifying its structure and the chemical processes in which it is involved. To better understand the species in solution associated with changes in pH, thermodynamic study (potentiometry, calorimetry and NMR spectroscopy) about the protonation pathway of glyphosate is performed. Experimental results confirmed that the order of successive protonation sites of totally deprotonated glyphosate is phosphonate oxygen, amino nitrogen, and finally carboxylate oxygen. This trend is in agreement with the most recent theoretical work in the literature on the subject ( J. Phys. Chem. A 2015, , 119 , 5241 - 5249 ). The result is important because it confirms that the protonated site of glyphosate in pH range 7-8, is not on the amino but on the phosphonate group instead. This corrected information can improve the understanding of the glyphosate chemical and biochemical action. PMID:26862689

  9. Study of open charm production in proton+proton collisions at center of mass energies = 200 GeV

    NASA Astrophysics Data System (ADS)

    Butsyk, Sergey

    2005-11-01

    The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) with its unique electron identification system enables us to perform high precision measurements of electron yields. By measuring electron production at high transverse momentum, we can disentangle the contribution of electrons originating from semi-leptonic decays of heavy quarks (charm or bottom) from the less interesting "photonic" decay modes of light mesons. D/B mesons carry single heavy valence quarks and are usually referred to as "Open Charm" and "Open Bottom" particles, differentiating them from Closed Flavor particles such as J/psi, and Y mesons. Due to the large mass of the heavy quarks, their production mechanisms can be adequately explained by perturbative QCD (pQCD) theory. This dissertation presents the measurement of electrons from heavy flavor decays in proton + proton collisions at RHIC at collision energy s = 200 GeV over a wide range of transverse moment (0.4 < pT < 5 GeV/c). Two independent analysis techniques of signal extraction were performed. The "Cocktail" subtraction is based on the calculation and subtraction of the expected "photon-related" electron background based upon measured yields of light mesons. The "Converter" subtraction is based upon a direct measurement of photon yields achieved introducing additional material in the PHENIX acceptance and deducing the photon abundance by measuring the increase in electron yield. This is the first measurement of the Open Charm crossection at this collision energy and it is an important baseline measurement for comparison with nucleus + nucleus collisions. The modification of Open Charm production in heavy ion collisions compared to the presented p + p result can be used to study the final state interaction of the heavy quarks with hot dense matter inside the collisions. The results of the Open Charm measurements are compared to current pQCD predictions both in Leading Order (LO) O a2s and Next-to-Leading Order (NLO) O a3s

  10. Fragmentation Patterns and Mechanisms of Singly and Doubly Protonated Peptoids Studied by Collision Induced Dissociation

    NASA Astrophysics Data System (ADS)

    Ren, Jianhua; Tian, Yuan; Hossain, Ekram; Connolly, Michael D.

    2016-04-01

    Peptoids are peptide-mimicking oligomers consisting of N-alkylated glycine units. The fragmentation patterns for six singly and doubly protonated model peptoids were studied via collision-induced dissociation tandem mass spectrometry. The experiments were carried out on a triple quadrupole mass spectrometer with an electrospray ionization source. Both singly and doubly protonated peptoids were found to fragment mainly at the backbone amide bonds to produce peptoid B-type N-terminal fragment ions and Y-type C-terminal fragment ions. However, the relative abundances of B- versus Y-ions were significantly different. The singly protonated peptoids fragmented by producing highly abundant Y-ions and lesser abundant B-ions. The Y-ion formation mechanism was studied through calculating the energetics of truncated peptoid fragment ions using density functional theory and by controlled experiments. The results indicated that Y-ions were likely formed by transferring a proton from the C-H bond of the N-terminal fragments to the secondary amine of the C-terminal fragments. This proton transfer is energetically favored, and is in accord with the observation of abundant Y-ions. The calculations also indicated that doubly protonated peptoids would fragment at an amide bond close to the N-terminus to yield a high abundance of low-mass B-ions and high-mass Y-ions. The results of this study provide further understanding of the mechanisms of peptoid fragmentation and, therefore, are a valuable guide for de novo sequencing of peptoid libraries synthesized via combinatorial chemistry.

  11. Manipulating the proton transfer process in molecular complexes: synthesis and spectroscopic studies.

    PubMed

    Panja, Sumit Kumar; Dwivedi, Nidhi; Saha, Satyen

    2016-08-01

    The proton transfer process in carefully designed molecular complexes has been investigated directly in the solid and solution phase. SCXRD studies have been employed to investigate the N-H-O bonding interaction sites of the molecular complexes, with additional experimental support from FTIR and Raman spectroscopic studies, to gain information on the relative position of hydrogen in between the N and O centers. Further, the proton transfer process in solution is studied using UV-Visible spectroscopy through monitoring the intramolecular charge transfer (ICT) process in these molecular complexes, which is primarily governed by the number of electron withdrawing groups (nitro groups) on proton donor moieties (NP, DNP and TNP). It is found that the magnitude of the ICT process depends on the extent of proton transfer, which on the other hand depends on the relative stabilities of the constituent species (phenolate species). A correlation is observed between an increase in the number of nitro groups and an increase in the melting point of the molecular complexes, indicating the enhancement of ionic character due to the proton transfer process. The aliphatic H-bonding is identified and monitored using (1)H-NMR spectroscopy, which reveals that the identity of molecular complexes in solution interestingly depends on the extent of proton transfer, in addition to the nature of the solvents. The aliphatic C-H-O H-bonding interaction between the oxygen atom of the nitro group and the alkyl hydrogen in piperidinium was also found to play a significant role in strengthening the primary interaction involving a hydrogen transfer process. The conductivity of the molecular complexes increases with an increase in the number of nitro groups, indicating the enhancement in ionic character of the molecular complexes. PMID:27424765

  12. Fragmentation Patterns and Mechanisms of Singly and Doubly Protonated Peptoids Studied by Collision Induced Dissociation.

    PubMed

    Ren, Jianhua; Tian, Yuan; Hossain, Ekram; Connolly, Michael D

    2016-04-01

    Peptoids are peptide-mimicking oligomers consisting of N-alkylated glycine units. The fragmentation patterns for six singly and doubly protonated model peptoids were studied via collision-induced dissociation tandem mass spectrometry. The experiments were carried out on a triple quadrupole mass spectrometer with an electrospray ionization source. Both singly and doubly protonated peptoids were found to fragment mainly at the backbone amide bonds to produce peptoid B-type N-terminal fragment ions and Y-type C-terminal fragment ions. However, the relative abundances of B- versus Y-ions were significantly different. The singly protonated peptoids fragmented by producing highly abundant Y-ions and lesser abundant B-ions. The Y-ion formation mechanism was studied through calculating the energetics of truncated peptoid fragment ions using density functional theory and by controlled experiments. The results indicated that Y-ions were likely formed by transferring a proton from the C-H bond of the N-terminal fragments to the secondary amine of the C-terminal fragments. This proton transfer is energetically favored, and is in accord with the observation of abundant Y-ions. The calculations also indicated that doubly protonated peptoids would fragment at an amide bond close to the N-terminus to yield a high abundance of low-mass B-ions and high-mass Y-ions. The results of this study provide further understanding of the mechanisms of peptoid fragmentation and, therefore, are a valuable guide for de novo sequencing of peptoid libraries synthesized via combinatorial chemistry. Graphical Abstract ᅟ. PMID:26832347

  13. Molecular Dynamics Study of the Proposed Proton Transport Pathways in [FeFe]-Hydrogenase

    SciTech Connect

    Ginovska-Pangovska, Bojana; Ho, Ming-Hsun; Linehan, John C.; Cheng, Yuhui; Dupuis, Michel; Raugei, Simone; Shaw, Wendy J.

    2014-01-15

    Possible proton channels in Clostridium pasteurianum [FeFe]-hydrogenase were investigated with molecular dynamics simulations. This study was undertaken to discern proposed channels, compare their properties, evaluate the functional channel, and to provide insight into the features of an active proton channel. Our simulations suggest that protons are not transported through water wires. Instead, a five-residue motif (E282, S319, E279, HOH, C299) was found to be the likely channel, consistent with experimental observations. This channel connects the surface of the enzyme and the di-thiomethylamine bridge of the catalytic H-cluster, permitting the transport of protons. The channel was found to have a persistent hydrogen bonded core (residues E279 to S319), with less persistent hydrogen bonds at the ends of the channel. The hydrogen bond occupancy in this network was found to be sensitive to the protonation state of the residues in the channel, with different protonation states enhancing or stabilizing hydrogen bonding in different regions of the network. Single site mutations to non-hydrogen bonding residues break the hydrogen bonding network at that residue, consistent with experimental observations showing catalyst inactivation. In many cases, these mutations alter the hydrogen bonding in other regions of the channel which may be equally important in catalytic failure. A correlation between the protein dynamics near the proton channel and the redox partner binding regions was also found as a function of protonation state. The likely mechanism of proton movement in [FeFe]-hydrogenases is discussed based on the structural analysis presented here. This work was funded by the DOE Office of Science Early Career Research Program through the Office of Basic Energy Sciences. Computational resources were provided at W. R. Wiley Environmental Molecular Science Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy’s Office of

  14. Experimental Studies of Fast Protons Originated from Fusion Reactions in Plasma-Focus Discharges

    SciTech Connect

    Malinowska, A.; Malinowski, K.; Sadowski, M. J.; Zebrowski, J.; Szydlowski, A.

    2008-03-19

    The paper describes results of the recent measurements of fusion-reaction protons, which were performed within the PF-360 facility operated at the IPJ in Swierk, Poland. The main aim of those studies was to perform time-integrated measurements of fast protons (of energy of about 3 MeV) by means of ion-pinhole cameras, which were equipped with solid state nuclear track detectors (SSNTD) of the PM-355 type and absorption filters made of thin metal foils. In order to determine the spatial distribution of fusion-produced protons the use was made of several miniature pinhole cameras placed at different angles to the PF-360 axis. The irradiated and etched detectors were analyzed with an optical microscope coupled with a CCD camera and a PC unit.

  15. Experimental study of the beta-delayed proton decays of {sup 145,147}Er

    SciTech Connect

    Ma, F.; Zhou, X. H.; Zheng, Y.; Xu, S. W.; Xie, Y. X.; Chen, L.; Lei, X. G.; Guo, Y. X.; Zhang, Y. H.; Li, Z. K.; Qiang, Y. H.; Guo, S.; Wang, H. X.; Zhou, H. B.; Ding, B.; Li, G. S.; Zhang, N. T.

    2010-04-15

    The beta-delayed proton decays of {sup 145,147}Er have been studied experimentally using the {sup 58}Ni+{sup 92}Mo reaction at beam energy of 383 MeV. On the basis of a He-jet apparatus coupled with a tape transport system, the beta-delayed proton radioactivities both from the nus{sub 1/2} ground state and the nuh{sub 11/2} isomer in {sup 145,147}Er were observed by proton-gamma coincidence measurements. By analyzing the time distributions of the 4{sup +}->2{sup +}gamma transitions in the granddaughter nuclei {sup 144,146}Dy, the half-lives of 1.0+-0.3 s and 1.6+-0.2 s have been deduced for the nuh{sub 11/2} isomers in {sup 145,147}Er, respectively.

  16. Biological Effects in Coral Biomineralization: The Ion-Microprobe Revolution

    NASA Astrophysics Data System (ADS)

    Meibom, A.

    2004-12-01

    Scleractinian corals are among the most prolific biomineralizing organisms on Earth and massive, reef-building corals are used extensively as proxies for past variations in the global climate. It is therefore of wide interest to understand the degree to which biological versus inorganic processes control the chemistry of the coral skeleton. Early workers considered aragonitic coral skeleton formation to be a purely physiochemical process. More recent studies have increasingly emphasized the role of a skeletal organic matrix, or intercalated organic macro-molecules that control the macroscopic shape and size of the growing crystals. It is now well established that organic compounds play a key role in controlling the morphology of crystals in a wide variety of calcium carbonate biomineralization processes by binding to specific sites, thereby causing direction-specific binding energies on the crystal surfaces. Macro-molecules, such as aspartic acid-rich or glutamic proteins and sulfated polysaccharides, are known to be embedded within the aragonitic skeletal components of coral. In addition, endosymbiotic algae and the layer of cells adjacent to the mineralizing surface, the calicoblastic ectoderm, are believed to play important roles in driving and controlling hermatypic coral skeletogenesis. However, until recently, further progress has been somewhat limited because it was not possible to obtain chemical analyses of the coral skeleton with sufficiently high spatial resolution and sensitivity to correlate chemical variations with the micrometer scale organization of its different structural components. The recent emergence of new ion microprobe technology is changing this situation radically. Conventional ion microprobe and laser ablation techniques have already contributed substantially to our knowledge about the micro-distribution of key trace elements such as B, Mg, Sr, Ba and U. However, with the development of the NanoSIMS, a newly designed ion microprobe

  17. Studies on PVA based nanocomposite Proton Exchange Membrane for Direct methanol fuel cell (DMFC) applications

    NASA Astrophysics Data System (ADS)

    Bahavan Palani, P.; Kannan, R.; Rajashabala, S.; Rajendran, S.; Velraj, G.

    2015-02-01

    Different concentrations of Poly (vinyl alcohol)/Montmorillonite (PVA/MMT) based proton exchange membranes (PEMs) have been prepared by solution casting method. The structural and electrical properties of these composite membranes have been characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopic (FTIR) and AC impedance spectroscopic methods. The conductivity of the PEMs has been estimated for the different concentration of MMT. Water/Methanol uptake measurement were also analyzed for the prepared PEMs and presented. The proton conductivity studies were carried out at room temperature with 100% of humidity.

  18. Study of the effects of high-energy proton beams on escherichia coli

    NASA Astrophysics Data System (ADS)

    Park, Jeong Chan; Jung, Myung-Hwan

    2015-10-01

    Antibiotic-resistant bacterial infection is one of the most serious risks to public health care today. However, discouragingly, the development of new antibiotics has progressed little over the last decade. There is an urgent need for alternative approaches to treat antibiotic-resistant bacteria. Novel methods, which include photothermal therapy based on gold nano-materials and ionizing radiation such as X-rays and gamma rays, have been reported. Studies of the effects of high-energy proton radiation on bacteria have mainly focused on Bacillus species and its spores. The effect of proton beams on Escherichia coli (E. coli) has been limitedly reported. Escherichia coli is an important biological tool to obtain metabolic and genetic information and is a common model microorganism for studying toxicity and antimicrobial activity. In addition, E. coli is a common bacterium in the intestinal tract of mammals. In this research, the morphological and the physiological changes of E. coli after proton irradiation were investigated. Diluted solutions of cells were used for proton beam radiation. LB agar plates were used to count the number of colonies formed. The growth profile of the cells was monitored by using the optical density at 600 nm. The morphology of the irradiated cells was observed with an optical microscope. A microarray analysis was performed to examine the gene expression changes between irradiated samples and control samples without irradiation. E coli cells have observed to be elongated after proton irradiation with doses ranging from 13 to 93 Gy. Twenty-two were up-regulated more than twofold in proton-irradiated samples (93 Gy) compared with unexposed one.

  19. Low-x QCD studies with forward jets in proton-proton collisions at {radical}(s) = 14 TeV

    SciTech Connect

    Cerci, Salim; D'Enterria, David

    2009-03-23

    Forward (di)jet measurements are a useful tool to constrain the Partom Distribution Functions (PDFs) at low values of parton momentum fraction x and to study the possible onset of BFKL or gluon saturation QCD evolutions in the proton. We present studies of jet reconstruction capabilities in the CMS Hadron Forward (HF) calorimeter (3<|{eta}|<5). The expected sensitivity of the inclusive forward jet p{sub T} spectrum to the proton PDF, as well as the azimuthal decorrelation of Mueller-Navelet jets with a large rapidity separation are presented for p-p collisions at {radical}(s) = 14 TeV.

  20. Glutamatergic Effects of Divalproex in Adolescents with Mania: A Proton Magnetic Resonance Spectroscopy Study

    ERIC Educational Resources Information Center

    Strawn, Jeffrey R.; Patel, Nick C.; Chu, Wen-Jang; Lee, Jing-Huei; Adler, Caleb M.; Kim, Mi Jung; Bryan, Holly S.; Alfieri, David C.; Welge, Jeffrey A.; Blom, Thomas J.; Nandagopal, Jayasree J.; Strakowski, Stephen M.; DelBello, Melissa P.

    2012-01-01

    Objectives: This study used proton magnetic resonance spectroscopy ([superscript 1]H MRS) to evaluate the in vivo effects of extended-release divalproex sodium on the glutamatergic system in adolescents with bipolar disorder, and to identify baseline neurochemical predictors of clinical remission. Method: Adolescents with bipolar disorder who were…

  1. Synchrotron based proton drivers

    SciTech Connect

    Weiren Chou

    2002-09-19

    Proton drivers are the proton sources that produce intense short proton bunches. They have a wide range of applications. This paper discusses the proton drivers based on high-intensity proton synchrotrons. It gives a review of the high-intensity proton sources over the world and a brief report on recent developments in this field in the U.S. high-energy physics (HEP) community. The Fermilab Proton Driver is used as a case study for a number of challenging technical design issues.

  2. Proton irradiation induced defects in GaN: Rutherford backscattering and thermally stimulated current studies

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Nishikata, N.; Kamioka, K.; Kuriyama, K.; Kushida, K.

    2016-03-01

    The proton irradiation induced defects in GaN are studied by combining elastic recoil detection analysis (ERDA), thermally stimulated current (TSC), and Rutherford backscattering spectroscopy (RBS) measurements. The proton irradiation (peak concentration: 1.0 × 1015 cm-2) into GaN films with a thickness of 3 μm is performed using a 500 keV implanter. The proton concentration by a TRIM simulation is maximum at 3600 nm in depth, which means that the proton beam almost passes through the GaN film. The carrier concentration decreases three orders of magnitude to 1015 cm-3 by the proton irradiation, suggesting the existence of the proton irradiation-induced defects. The ERDA measurements using the 1.5 MeV helium beam can evaluate hydrogen from the surface to ∼300 nm. The hydrogen concentration at ∼220 nm is ∼8.3 × 1013 cm-2 and ∼1.0 × 1014 cm-2 for un-irradiated and as-irradiated samples, respectively, suggesting that electrical properties are almost not affected by hydrogen. TSC measurements show a broad spectrum at around 110 K which can be divided into three traps, P1 (ionization energy 173 meV), P2 (251 meV), and P3 (330 meV). The peak intensity of P1 is much larger than that of P2 and P3. These traps are related to the N vacancy and/or complex involving N vacancy (P1), neutral Ga vacancy (VGa) (P2), and complex involving VGa (P3). The Ga displacement concentration evaluated by RBS measurements is 1.75 × 1019 cm-3 corresponding to 1/1000 of the Ga concentration in GaN. The observed Ga displacement may be origins of P2 and P3 traps.

  3. Brain activity mapping at multiple scales with silicon microprobes containing 1,024 electrodes

    PubMed Central

    Shobe, Justin L.; Claar, Leslie D.; Parhami, Sepideh; Bakhurin, Konstantin I.

    2015-01-01

    The coordinated activity of neural ensembles across multiple interconnected regions has been challenging to study in the mammalian brain with cellular resolution using conventional recording tools. For instance, neural systems regulating learned behaviors often encompass multiple distinct structures that span the brain. To address this challenge we developed a three-dimensional (3D) silicon microprobe capable of simultaneously measuring extracellular spike and local field potential activity from 1,024 electrodes. The microprobe geometry can be precisely configured during assembly to target virtually any combination of four spatially distinct neuroanatomical planes. Here we report on the operation of such a device built for high-throughput monitoring of neural signals in the orbitofrontal cortex and several nuclei in the basal ganglia. We perform analysis on systems-level dynamics and correlations during periods of conditioned behavioral responding and rest, demonstrating the technology's ability to reveal functional organization at multiple scales in parallel in the mouse brain. PMID:26133801

  4. Determination of nitrogen in coal macerals using electron microprobe technique-experimental procedure

    USGS Publications Warehouse

    Mastalerz, Maria; Gurba, L.W.

    2001-01-01

    This paper discusses nitrogen determination with the Cameca SX50 electron microprobe using PCO as an analyzing crystal. A set of conditions using differing accelerating voltages, beam currents, beam sizes, and counting times were tested to determine parameters that would give the most reliable nitrogen determination. The results suggest that, for the instrumentation used, 10 kV, current 20 nA, and a counting time of 20 s provides the most reliable nitrogen determination, with a much lower detection limit than the typical concentration of this element in coal. The study demonstrates that the electron microprobe technique can be used to determine the nitrogen content of coal macerals successfully and accurately. ?? 2001 Elsevier Science B.V. All rights reserved.

  5. Study of Polarized Sea Quark Distributions in Polarized Proton-Proton Collisions at sq root(s) = 500 GeV with PHENIX

    SciTech Connect

    Mibe, Tsutomu

    2009-08-04

    The PHENIX spin program studies the flavor structure of the polarized sea quark distributions in polarized proton-proton collisions. Starting from 2009 run, the quark and antiquark polarization, sorted by flavor, will be investigated with the parity-violating single-spin asymmetry of W-boson production at the collision energy of sq root(s) = 500 GeV. High momentum muons from W-boson decay are detected in the PHENIX muon arms. The muon trigger is being upgraded to allow one to select high momentum muons.

  6. Proton beam studies with a 1.25 MeV, cw radio frequency quadrupole linac

    SciTech Connect

    Bolme, G.O.; Hardek, T.W.; Hansborough, L.D.

    1998-12-31

    A high-current, cw linear accelerator has been proposed as a spallation neutron source driver for tritium production. Key features of this accelerator are high current (100 mA), low emittance-growth beam propagation, cw operation, high efficiency, and minimal maintenance downtime. A 268 MHz, cw radio frequency quadrupole (RFQ) LINAC section and klystrode based rf system were obtained from the Chalk River Laboratories and were previously installed at LANL to support systems development and advanced studies in support of cw, proton accelerators. A variation of the Low Energy Demonstration Accelerator (LEDA) proton injector, modified to operate at 50 keV, was mated to the RFQ and was operated to support advance developments for the Accelerator Production of Tritium (APT) program. High current, proton beam studies were completed which focused on the details of injector-RFQ integration, development of beam diagnostics, development of operations procedures, and personnel and equipment safety systems integration. This development led to acceleration of up to 100 mA proton beam.

  7. Feasibility studies on time-like proton electromagnetic form factors at PANDA-FAIR

    NASA Astrophysics Data System (ADS)

    Zimmermann, Iris; Dbeyssi, Alaa; Khaneft, Dmitry

    2016-05-01

    This contribution reports on the latest status of the feasibility studies for the measurement of time-like proton electromagnetic form factors (FF's) at the PANDA experiment [1] at FAIR (Germany). Electromagnetic FF's are fundamental quantities parameterizing the electric and magnetic structure of hadrons. In the time-like region proton FF's can be accessed experimentally through the annihilation processes p ¯p → l+l- (l = e, μ), assuming that the interaction takes place through the exchange of one virtual photon. Due to the low luminosity available at colliders in the past, an individual determination of the time-like electric and magnetic proton FF's was not feasible. The statistical precision, at which the proton FF's will be determined at PANDA, is estimated for both signal processes p ¯p → l+l- (l = e, μ) using the PandaRoot software, which encompasses full detector simulation and event reconstruction. The signal identification and suppression of the main background process (p ¯p → π+π-) is studied. Different methods have been used to generate and analyze the processes of interest. The results from the different analyses show that time-like electromagnetic FF's can be measured at PANDA with unprecedented statistical accuracy.

  8. The use of the laser Raman microprobe for the determination of salinity in fluid inclusions

    SciTech Connect

    Mernagh, T.P.; Wilde, A.R. )

    1989-04-01

    The O-H stretching region (2,800-3,800 cm{sup {minus}1}) in Raman spectra of aqueous solutions is sensitive to changes in the salt concentration. This permits determination of the salinity in the aqueous phase of fluid inclusions (at room temperature) by calculating skewing parameters from Raman microprobe spectra. The technique does not require detailed knowledge of the fluid composition and can be applied to most chloride solutions which commonly occur in fluid inclusions. Studies of synthetic fluid inclusions from the NaCl-H{sub 2}O system show that salinities up to halite saturation may be determined to within {plus minus}2 wt%. Well-characterized fluid inclusions from the unconformity-related uranium deposits of Nabarlek and Koongarra, Northern Territory, Australia, were studied with the laser Raman microprobe. The salinities determined from the Raman spectra are comparable to those obtained using standard microthermometric techniques. The Raman microprobe technique has the advantage of not requiring analogy to binary salt-water phase diagrams which cannot adequately model the complex brines in these inclusions. Variations in the concentration of salt hydrates, observed in Raman spectra of frozen inclusion, validated the salinities derived from the Raman skewing parameters obtained at room temperature. The Raman analyses confirm previous microthermometric evidence for trapping of discrete high and low salinity fluids.

  9. SU-E-J-175: Proton Dose Calculation On Scatter-Corrected CBCT Image: Feasibility Study for Adaptive Proton Therapy

    SciTech Connect

    Park, Y; Winey, B; Sharp, G

    2014-06-01

    Purpose: To demonstrate feasibility of proton dose calculation on scattercorrected CBCT images for the purpose of adaptive proton therapy. Methods: Two CBCT image sets were acquired from a prostate cancer patient and a thorax phantom using an on-board imaging system of an Elekta infinity linear accelerator. 2-D scatter maps were estimated using a previously introduced CT-based technique, and were subtracted from each raw projection image. A CBCT image set was then reconstructed with an open source reconstruction toolkit (RTK). Conversion from the CBCT number to HU was performed by soft tissue-based shifting with reference to the plan CT. Passively scattered proton plans were simulated on the plan CT and corrected/uncorrected CBCT images using the XiO treatment planning system. For quantitative evaluation, water equivalent path length (WEPL) was compared in those treatment plans. Results: The scatter correction method significantly improved image quality and HU accuracy in the prostate case where large scatter artifacts were obvious. However, the correction technique showed limited effects on the thorax case that was associated with fewer scatter artifacts. Mean absolute WEPL errors from the plans with the uncorrected and corrected images were 1.3 mm and 5.1 mm in the thorax case and 13.5 mm and 3.1 mm in the prostate case. The prostate plan dose distribution of the corrected image demonstrated better agreement with the reference one than that of the uncorrected image. Conclusion: A priori CT-based CBCT scatter correction can reduce the proton dose calculation error when large scatter artifacts are involved. If scatter artifacts are low, an uncorrected CBCT image is also promising for proton dose calculation when it is calibrated with the soft-tissue based shifting.

  10. Identification of cosmogenic argon components in Allende by laser microprobe

    NASA Technical Reports Server (NTRS)

    Kirschbaum, C.

    1986-01-01

    New techniques are presented for using a laser microprobe to determine the spallation argon systematics of calcium-aluminum inclusions. The Ar-38(s) amounts determined for melilite and anorthite in a coarse-grained inclusion from Allende are 2.9 x 10 to the -8th and 1.3 x 10 to the -8th cc/g, respectively. The ratio of the amounts is consistent with the calcium contents of these two minerals. The Ar-38(s) amount determined for a fine-grained inclusion from Allende is 1.1 x 10 to the -8th cc/g. Calcium and potassium amounts were determined from irradiated samples of the same inclusions so that production of Ar-38 from calcium during the cosmic ray exposure of Allende could be determined for these samples. The production observed was 12.4 + or - 2.1 x 10 to the -8th cc STP Ar-38/g Ca for the coarse-grained inclusion and 9.9 + or - 2.4 cc STP Ar-38/g Ca for the fine-grained inclusion. No evidence of unusual exposure was observed in the two inclusions studied.

  11. Nickel geochemistry of a Philippine laterite examined by bulk and microprobe synchrotron analyses

    NASA Astrophysics Data System (ADS)

    Fan, Rong; Gerson, Andrea R.

    2011-11-01

    The Ni geochemistry of limonite and saprolite laterite ores from Pujada in the Philippines has been investigated using a mixture of laboratory and synchrotron techniques. Nickel laterite profiles are typically composed of complicated mineral assemblages, with Ni being distributed heterogeneously at the micron scale, and thus a high degree of spatial resolution is required for analysis. This study represents the first such analysis of Philippine laterite ores. Synchrotron bulk and microprobe X-ray absorption spectroscopy (XAS), comprising both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopies, together with synchrotron microprobe X-ray fluorescence microscopy (XFM) and diffraction (XRD) have been applied to provide quantitative analysis of the mineral components and Ni speciation. Synchrotron microprobe EXAFS spectroscopy suggests that the limonite Ni is associated with phyllomanganate via adsorption onto the Mn oxide layers and substitution for Mn within these layers. Laboratory scanning electron microscopy, coupled to electron dispersive spectroscopy analyses, indicates that Ni is also associated with concentrated Fe containing particles and this is further confirmed by synchrotron bulk and microprobe investigation. Linear combination fitting of the bulk EXAFS limonite data suggests 60 ± 15% of the Ni is associated with phyllomanganate, with the predominant fraction adsorbed above vacancies in the MnO 6 layers with the remainder being substituted for Mn within these layers. The remaining 40 ± 10% of the Ni in the limonite ore is incorporated into goethite through replacement of the Fe. In the saprolite ore, 90 ± 23% of the Ni is associated with a serpentine mineral, most likely lizardite, as a replacement for Mg. The remaining Ni is found within phyllomanganate adsorbed above vacancies in the MnO 6 layers.

  12. Ab Initio Study of Hydration and Proton Dissociation in Ionomer Membranes

    SciTech Connect

    Idupulapati, Nagesh B.; Devanathan, Ramaswami; Dupuis, Michel

    2010-07-01

    We present a comparative study of proton dissociation in various functional acidic units that are promising candidates as building blocks for polymeric electrolyte membranes. Minimum energy structures for four acidic moieties with clusters of 1-6 water molecules were determined using density functional theory at the B3LYP/6-311G** level starting from chemically rational initial configurations. The perfluoro sulfonyl imide acid group (CF3CF2SO2NHSO2CF3) was observed to be the strongest acid, due to the substantial electron withdrawing effect of both fluorocarbon groups. The hydrophilic functional group (CH3OC6H3OCH3C6H4SO3H) of sulfonated polyetherether ketone (SPEEK) membrane was found to be the strongest base with the acidic proton dissociation requiring the addition of six water molecules and the hydrated proton being more tightly bound to the conjugate base. Even though both perfluoro sulfonyl imides and sulfonic acids (hydrophilic functional groups for sulfonyl imide and Nafion ionomers respectively) required only three water molecules to exhibit spontaneous proton dissociation, the largest possible solvent-separated hydronium ion was attained only for the sulfonyl imide moiety. These results provide a scientific basis for understanding the improved conductivity of perfluorinated sulfonyl imide-based membranes relative to that of the widely-used Nafion membrane.

  13. Numerical study of a linear accelerator using laser-generated proton beams as a source

    SciTech Connect

    Antici, P.; Fazi, M.; Migliorati, M.; Palumbo, L.; Lombardi, A.; Audebert, P.; Fuchs, J.

    2008-12-15

    The injection of laser-generated protons through conventional drift tube linear accelerators (linacs) has been studied numerically. For this, we used the parameters of the proton source produced by ultraintense lasers, i.e., with an intrinsic high beam quality. The numerical particle tracing code PARMELA[L. M. Young and J. H. Billen, LANL Report No. LA-UR-96-1835, 2004] is then used to inject experimentally measured laser-generated protons with energies of 7{+-}0.1 MeV and rms un-normalized emittance of 0.180 mm mrad into one drift tube linac tank that accelerated them to more than 14 MeV. The simulations exhibit un-normalized emittance growths of 8 in x direction and 22.6 in y direction, with final emittances lower than those produced using conventional sources, allowing a potential luminosity gain for the final beam. However, the simulations also exhibit a limitation in the allowed injected proton charge as, over 0.112 mA, space charge effect worsens significantly the beam emittance.

  14. Proton and tritium NMR relaxation studies of peptide inhibitor binding to bacterial collagenase: Conformation and dynamics

    SciTech Connect

    Dive, V.; Lai, A.; Valensin, G.; Saba, G.; Yiotakis, A.; Toma, F. )

    1991-02-15

    The interaction of succinyl-Pro-Ala, a competitive inhibitor of Achromobacter iophagus collagenase, with the enzyme was studied by longitudinal proton and tritium relaxation. Specific deuterium and tritium labeling of the succinyl part at vicinal positions allowed the measurement of the cross-relaxation rates of individual proton or tritium spin pairs in the inhibitor-enzyme complex as well as in the free inhibitor. Overall correlation times, internuclear distances, and qualitative information on the internal mobility in Suc1 (as provided by the generalized order parameter S2) could be deduced by the comparison of proton and tritium cross-relaxation of spin pairs at complementary positions in the -CH2- CH2- moiety as analyzed in terms of the model-free approach by Lipari and Szabo. The conformational and motional parameters of the inhibitor in the free and enzyme-bound state were directly compared by this method. The measurement of proton cross-relaxation in the Ala residue provided additional information on the inhibitor binding. The determination of the order parameter in different parts of the inhibitor molecule in the bound state indicates that the succinyl and alanyl residues are primarily involved in the interaction with the enzyme activity site. The succinyl moiety, characterized in solution by the conformational equilibrium among the three staggered rotamers--i.e., trans: 50%; g+: 20%; g-: 30%--adopted in the bound state the unique trans conformation.

  15. Two-dimensional infrared study of 3-azidopyridine as a potential spectroscopic reporter of protonation state

    SciTech Connect

    Nydegger, Michael W.; Dutta, Samrat; Cheatum, Christopher M.

    2010-10-07

    The lack of general spectroscopic probes that can be used in a range of systems to probe kinetics and dynamics is a major obstacle to the widespread application of two-dimensional infrared (2D IR) spectroscopy. We have studied 3-azidopyridine to characterize its potential as a probe of the protonation state of the pyridine ring. We find that the azido-stretching vibration is split by accidental Fermi resonance interactions with one or more overtones and combination states. Using 2D IR spectroscopy, we determine the state structure of the resulting eigenstates for complexes of 3-azidopyridine with formic acid and trifluoroacetic acid in which the pyridine ring is unprotonated and protonated, respectively. Based on the measurements, we develop a two-oscillator depurturbation model to determine the energies and couplings of the zeroth-order azido-stretching state and the perturbing dark state that couples to it. Based on these results, we conclude that the azido-stretching vibration is, in fact, sensitive to the protonation state of the pyridine shifting up in frequency by 8 cm{sup -1} in the complex with trifluoroacetic acid relative to the formic acid complex. These results suggest that, although 3-azidopyridine is not suitable as a spectroscopic probe, the approach of employing an organic azide as a remote probe of protonation state holds significant promise.

  16. The proton therapy nozzles at Samsung Medical Center: A Monte Carlo simulation study using TOPAS

    NASA Astrophysics Data System (ADS)

    Chung, Kwangzoo; Kim, Jinsung; Kim, Dae-Hyun; Ahn, Sunghwan; Han, Youngyih

    2015-07-01

    To expedite the commissioning process of the proton therapy system at Samsung Medical Center (SMC), we have developed a Monte Carlo simulation model of the proton therapy nozzles by using TOol for PArticle Simulation (TOPAS). At SMC proton therapy center, we have two gantry rooms with different types of nozzles: a multi-purpose nozzle and a dedicated scanning nozzle. Each nozzle has been modeled in detail following the geometry information provided by the manufacturer, Sumitomo Heavy Industries, Ltd. For this purpose, the novel features of TOPAS, such as the time feature or the ridge filter class, have been used, and the appropriate physics models for proton nozzle simulation have been defined. Dosimetric properties, like percent depth dose curve, spreadout Bragg peak (SOBP), and beam spot size, have been simulated and verified against measured beam data. Beyond the Monte Carlo nozzle modeling, we have developed an interface between TOPAS and the treatment planning system (TPS), RayStation. An exported radiotherapy (RT) plan from the TPS is interpreted by using an interface and is then translated into the TOPAS input text. The developed Monte Carlo nozzle model can be used to estimate the non-beam performance, such as the neutron background, of the nozzles. Furthermore, the nozzle model can be used to study the mechanical optimization of the design of the nozzle.

  17. Proton Therapy

    MedlinePlus

    ... nucleus is surrounded by electrons. In proton therapy, beams of fast-moving protons are used to destroy ... atoms to release proton, neutron, and helium ion beams. In this highly specialized form of radiosurgery , proton ...

  18. Design study of the ESS-Bilbao 50 MeV proton beam line for radiobiological studies

    NASA Astrophysics Data System (ADS)

    Huerta-Parajon, M.; Martinez-Ballarin, R.; Abad, E.

    2015-02-01

    The ESS-Bilbao proton accelerator facility has been designed fulfilling the European Spallation Source (ESS) specifications to serve as the Spanish contribution to the ESS construction. Furthermore, several applications of the ESS-Bilbao proton beam are being considered in order to contribute to the knowledge in the field of radiobiology, materials and aerospace components. Understanding of the interaction of radiation with biological systems is of vital importance as it affects important applications such as cancer treatment with ion beam therapy among others. ESS-Bilbao plans to house a facility exclusively dedicated to radiobiological experiments with protons up to 50 MeV. Beam line design, optimisation and initial calculations of flux densities and absorbed doses were undertaken using the Monte Carlo simulation package FLUKA. A proton beam with a flux density of about 106 protons/cm2 s reaches the water sample with a flat lateral distribution of the dose. The absorbed dose at the pristine Bragg peak calculated with FLUKA is 2.4 ± 0.1 Gy in 1 min of irradiation time. This value agrees with the clinically meaningful dose rates, i.e. around 2 Gy/min, used in hadrontherapy. Optimisation and validation studies in the ESS-Bilbao line for radiobiological experiments are detailed in this article.

  19. Proton radiography to improve proton therapy treatment

    NASA Astrophysics Data System (ADS)

    Takatsu, J.; van der Graaf, E. R.; Van Goethem, M.-J.; van Beuzekom, M.; Klaver, T.; Visser, J.; Brandenburg, S.; Biegun, A. K.

    2016-01-01

    The quality of cancer treatment with protons critically depends on an accurate prediction of the proton stopping powers for the tissues traversed by the protons. Today, treatment planning in proton radiotherapy is based on stopping power calculations from densities of X-ray Computed Tomography (CT) images. This causes systematic uncertainties in the calculated proton range in a patient of typically 3-4%, but can become even 10% in bone regions [1,2,3,4,5,6,7,8]. This may lead to no dose in parts of the tumor and too high dose in healthy tissues [1]. A direct measurement of proton stopping powers with high-energy protons will allow reducing these uncertainties and will improve the quality of the treatment. Several studies have shown that a sufficiently accurate radiograph can be obtained by tracking individual protons traversing a phantom (patient) [4,6,10]. Our studies benefit from the gas-filled time projection chambers based on GridPix technology [2], developed at Nikhef, capable of tracking a single proton. A BaF2 crystal measuring the residual energy of protons was used. Proton radiographs of phantom consisting of different tissue-like materials were measured with a 30×30 mm2 150 MeV proton beam. Measurements were simulated with the Geant4 toolkit.First experimental and simulated energy radiographs are in very good agreement [3]. In this paper we focus on simulation studies of the proton scattering angle as it affects the position resolution of the proton energy loss radiograph. By selecting protons with a small scattering angle, the image quality can be improved significantly.

  20. Studies of proton-irradiated cometary-type ice mixtures

    NASA Astrophysics Data System (ADS)

    Moore, M. H.; Donn, B.; Khanna, R.; A'Hearn, M. F.

    1983-06-01

    Cometary ice mixtures are studied in a laboratory experiment designed to simulate the temperature, pressure and radiation environments of the interstellar Oort cloud region, in order to test the hypothesized radiation synthesis mechanism for changing the characteristics of the outer few meters of a comet stored in the Oort cloud for 4.6 billion years. All experiments conducted confirm the synthesis of new molecular species in solid phase mixtures at 20 K. When CH4 is present in the irradiated ice mixture, long chained, voltaile hydrocarbon and CO2 are synthesized together with high molecular weight C compounds present in the room temperature residue. Due to radiation synthesis, about 1 percent of the ice was converted into a nonvolatile residue containing complicated C compounds not present in the blank samples. These results suggest that initial molecular abundances can be altered, and new species created, as a result of radiation synthesis. Irradiated mixtures exhibited thermoluminescence and pressure enhancements during warming, showing the synthesis of reactive species. Outbursts in new comets resulting from similar irradiation-induced exothermic activity would be expected to begin occurring at distances of the order of 100 AU.

  1. Proton nuclear magnetic resonance studies of mast cell histamine

    SciTech Connect

    Rabenstein, D.L.; Ludowyke, R.; Lagunoff, D.

    1987-11-03

    The state of histamine in mast cells was studied by /sup 1/H NMR spectroscopy. Spectra were measured for histamine in situ in intact mast cells, for histamine in suspensions of mast cell granule matrices that had been stripped of their membranes, and for histamine in solutions of heparin. The /sup 1/H NMR spectrum of intact mast cells is relatively simple, consisting predominantly of resonances for intracellular histamine superimposed on a weaker background of resonances from heparin and proteins of the cells. All of the intracellular histamine contributes of the NMR signals, indicating it must be relatively mobile and not rigidly associated with the negatively charged granule matrix. Spectra for intracellular histamine and for histamine in granule matrices are similar, indicating the latter to be a reasonable model for the in situ situation. The dynamics of binding of histamine by granule matrices and by heparin are considerably different; exchange of histamine between the bulk water and the granule matrices is slow on the /sup 1/H NMR time scale, whereas exchange between the free and bound forms in heparin solution is fast. The chemical shifts of resonances for histamine in mast cells are pH dependent, decreasing as the intragranule pH increases without splitting or broadening. The results are interpreted to indicate that histamine in mast cells is relatively labile, with rapid exchange between histamine and pools of free histamine in water compartments confined in the granule matrix.

  2. Studies of proton-irradiated cometary-type ice mixtures

    SciTech Connect

    Moore, M.H.; Donn, B.; Khanna, R.

    1983-06-01

    Cometary ice mixtures are studied in a laboratory experiment designed to simulate the temperature, pressure and radiation environments of the interstellar Oort cloud region, in order to test the hypothesized radiation synthesis mechanism for changing the characteristics of the outer few meters of a comet stored in the Oort cloud for 4.6 billion years. All experiments conducted confirm the synthesis of new molecular species in solid phase mixtures at 20 K. When CH4 is present in the irradiated ice mixture, long chained, voltaile hydrocarbon and CO2 are synthesized together with high molecular weight C compounds present in the room temperature residue. Due to radiation synthesis, about 1 percent of the ice was converted into a nonvolatile residue containing complicated C compounds not present in the blank samples. These results suggest that initial molecular abundances can be altered, and new species created, as a result of radiation synthesis. Irradiated mixtures exhibited thermoluminescence and pressure enhancements during warming, showing the synthesis of reactive species. Outbursts in new comets resulting from similar irradiation-induced exothermic activity would be expected to begin occurring at distances of the order of 100 AU. 40 references.

  3. Molecular organization in the native state of woody tissue: Studies of tertiary structure using the Raman microprobe solid state 13C NMR and biomimetic tertiary aggregates. Progress report, July 1, 1989--June 30, 1993

    SciTech Connect

    Atalla, R.H.

    1993-12-31

    We have previously shown that all relatively pure plant and bacterial celluloses are, in their native states, composites of two lattice forms, I{sub {alpha}} and I{sub {beta}}, and that the two forms possess molecular chains in the same conformations but with different hydrogen bonding patterns. In the current period we have demonstrated that in higher plant cell wall matrices, the hemicelluloses are likely to have a regulatory function during the aggregation of cellulose. Different hemicelluloses appear to influence the aggregation in different ways. We have also developed preliminary evidence indicating the hemicelluloses may have a protective function against the action of some cellulolytic enzymes. The specific accomplishments during the current period are detailed. Demonstration that hemicelluloses present during biogenesis can transform bacterial cellulose into a cellulose typical of higher plant celluloses, and that each hemicellulose has a different effect on the pattern of aggregation. Evidence is presented that the hemicelluloses may limit the action of certain cellulolytic enzymes, suggesting that their function may go beyond regulation to include passive resistance to cellulolytic pathogens. Enhancing the potential of the Raman microprobe technique for mapping variability of lignin in the cell wall by identifying the contribution of the different substructures of lignin to the intensity of the key band in the Raman spectrum of lignin. Mapping of the variability of lignin across two cell wall sections. The mappings have convoluted within them both composition and concentration, but they demonstrate the potential of the method and point to the improvements we are now making so as to distinguish between variability of concentration and variability of composition.

  4. NMR spectroscopy and perfusion of mammalian cells using surface microprobes.

    PubMed

    Ehrmann, Klaus; Pataky, Kristopher; Stettler, Matthieu; Wurm, Florian Maria; Brugger, Jürgen; Besse, Pierre-André; Popovic, Radivoje

    2007-03-01

    NMR spectra of mammalian cells are taken using surface microprobes that are based on microfabricated planar coils. The surface microprobe resembles a miniaturized Petri dish commonly used in biological research. The diameter of the planar coils is 1 mm. Chinese Hamster Ovaries are immobilized in a uniform layer on the microprobe surface or patterned by an ink-jet printer in the centre of the microcoil, where the rf-field of the planar microcoil is most uniform. The acquired NMR spectra show the prevalent metabolites found in mammalian cells. The volumes of the detected samples range from 25 nL to 1 nL (or 50,000 to 1800 cells). With an extended set-up that provides fluid inlets and outlets to the microprobe, the cells can be perfused within the NMR-magnet while constantly taking NMR spectra. Perfusion of the cells opens the way to increased cell viability for long acquisitions or to analysis of the cells' response to environmental change. PMID:17330170

  5. RAMAN MICROPROBE ANALYSIS OF STATIONARY SOURCE PARTICULATE POLLUTANTS

    EPA Science Inventory

    The application of Raman spectroscopy to the molecular characterization of individual particles from stationary sources is described. The NBS-developed Raman microprobe has been used to characterize microparticles of oil- and coal-fired power plant emissions and boiler samples co...

  6. Integrated Laser Microprobe (U-Th)/He and U/Pb Dating of Titanite and Zircon

    NASA Astrophysics Data System (ADS)

    Horne, A.; Van Soest, M. C.; Hodges, K. V.; Tripathy-Lang, A.

    2014-12-01

    The application of laser technologies for high spatial resolution dating has proven to be an important advancement in (U-Th)/He thermochronology. Excimer laser microprobes have been used to successfully date high U+Th minerals and are an especially promising way to determine the distribution of (U-Th)/He zircon ages in detrital sedimentary samples. We have also found that another detrital mineral, titanite, may be amenable to this method as well. While titanite contains lower concentrations of parent isotopes than zircon, and consequently less radiogenic 4He, its typically larger grain size allows for these characteristics to be mitigated by the use of larger laser beam diameters during the ablation process. With the integrated use of ICPMS, an established method for U/Pb geochronology, this phase of the laser microprobe (U-Th)/He technique can be modified slightly to enable (U-Th)/He and U/Pb 'double' dating of detrital samples. Here we present a proof of concept study demonstrating the viability of integrated laser microprobe (U-Th)/He and U/Pb through dating Oligocene Fish Canyon tuff titanite and zircon from Colorado. Our use of a well characterized sample with established (U-Th)/He and U/Pb dates allows us to fully evaluate the utility of this technique. By selecting medium- to fine-grained crystals we are able to simulate a realistic, uni-modal detrital sample. Using our modified laser microprobe approach, we are able to reproduce the expected age modes with an analytical imprecision roughly twice that of more established methods, a difference that has little practical effect on geologic interpretations. Additionally, we believe that the technique could prove a viable method for double dating detrital rutile and apatite, so long as characteristically lower U+Th concentrations in these minerals are balanced by appropriately scaled ablation pits in an aliquot unbiased by the need for larger detrital grains. Ultimately, integrated laser microprobe U/Pb and (U

  7. Study of the negative magneto-resistance of single proton-implanted lithium-doped ZnO microwires.

    PubMed

    Lorite, I; Zandalazini, C; Esquinazi, P; Spemann, D; Friedländer, S; Pöppl, A; Michalsky, T; Grundmann, M; Vogt, J; Meijer, J; Heluani, S P; Ohldag, H; Adeagbo, W A; Nayak, S K; Hergert, W; Ernst, A; Hoffmann, M

    2015-07-01

    The magneto-transport properties of single proton-implanted ZnO and of Li(7%)-doped ZnO microwires have been studied. The as-grown microwires were highly insulating and not magnetic. After proton implantation the Li(7%) doped ZnO microwires showed a non-monotonous behavior of the negative magneto-resistance (MR) at temperature above 150 K. This is in contrast to the monotonous NMR observed below 50 K for proton-implanted ZnO. The observed difference in the transport properties of the wires is related to the amount of stable Zn vacancies created at the near surface region by the proton implantation and Li doping. The magnetic field dependence of the resistance might be explained by the formation of a magnetic/non-magnetic heterostructure in the wire after proton implantation. PMID:26043764

  8. Study of the negative magneto-resistance of single proton-implanted lithium-doped ZnO microwires

    NASA Astrophysics Data System (ADS)

    Lorite, I.; Zandalazini, C.; Esquinazi, P.; Spemann, D.; Friedländer, S.; Pöppl, A.; Michalsky, T.; Grundmann, M.; Vogt, J.; Meijer, J.; Heluani, S. P.; Ohldag, H.; Adeagbo, W. A.; Nayak, S. K.; Hergert, W.; Ernst, A.; Hoffmann, M.

    2015-06-01

    The magneto-transport properties of single proton-implanted ZnO and of Li(7%)-doped ZnO microwires have been studied. The as-grown microwires were highly insulating and not magnetic. After proton implantation the Li(7%) doped ZnO microwires showed a non-monotonous behavior of the negative magneto-resistance (MR) at temperature above 150 K. This is in contrast to the monotonous NMR observed below 50 K for proton-implanted ZnO. The observed difference in the transport properties of the wires is related to the amount of stable Zn vacancies created at the near surface region by the proton implantation and Li doping. The magnetic field dependence of the resistance might be explained by the formation of a magnetic/non-magnetic heterostructure in the wire after proton implantation.

  9. Protein dynamics control proton transfer from bulk solvent to protein interior: A case study with a green fluorescent protein

    PubMed Central

    Saxena, Anoop M.; Udgaonkar, Jayant B.; Krishnamoorthy, Guruswamy

    2005-01-01

    The kinetics of proton transfer in Green Fluorescent Protein (GFP) have been studied as a model system for characterizing the correlation between dynamics and function of proteins in general. The kinetics in EGFP (a variant of GFP) were monitored by using a laser-induced pH jump method. The pH was jumped from 8 to 5 by nanosecond flash photolysis of the “caged proton,” o-nitrobenzaldehyde, and subsequent proton transfer was monitored by following the decrease in fluorescence intensity. The modulation of proton transfer kinetics by external perturbants such as viscosity, pH, and subdenaturing concentrations of GdnHCl as well as of salts was studied. The rate of proton transfer was inversely proportional to solvent viscosity, suggesting that the rate-limiting step is the transfer of protons through the protein matrix. The rate is accelerated at lower pH values, and measurements of the fluorescence properties of tryptophan 57 suggest that the enhancement in rate is associated with an enhancement in protein dynamics. The rate of proton transfer is nearly independent of temperature, unlike the rate of the reverse process. When the stability of the protein was either decreased or increased by the addition of co-solutes, including the salts KCl, KNO3, and K2SO4, a significant decrease in the rate of proton transfer was observed in all cases. The lack of correlation between the rate of proton transfer and the stability of the protein suggests that the structure is tuned to ensure maximum efficiency of the dynamics that control the proton transfer function of the protein. PMID:15937281

  10. Proton radiography and fluoroscopy of lung tumors: A Monte Carlo study using patient-specific 4DCT phantoms

    PubMed Central

    Han, Bin; Xu, X. George; Chen, George T. Y.

    2011-01-01

    Purpose: Monte Carlo methods are used to simulate and optimize a time-resolved proton range telescope (TRRT) in localization of intrafractional and interfractional motions of lung tumor and in quantification of proton range variations. Methods: The Monte Carlo N-Particle eXtended (MCNPX) code with a particle tracking feature was employed to evaluate the TRRT performance, especially in visualizing and quantifying proton range variations during respiration. Protons of 230 MeV were tracked one by one as they pass through position detectors, patient 4DCT phantom, and finally scintillator detectors that measured residual ranges. The energy response of the scintillator telescope was investigated. Mass density and elemental composition of tissues were defined for 4DCT data. Results: Proton water equivalent length (WEL) was deduced by a reconstruction algorithm that incorporates linear proton track and lateral spatial discrimination to improve the image quality. 4DCT data for three patients were used to visualize and measure tumor motion and WEL variations. The tumor trajectories extracted from the WEL map were found to be within ∼1 mm agreement with direct 4DCT measurement. Quantitative WEL variation studies showed that the proton radiograph is a good representation of WEL changes from entrance to distal of the target. Conclusions:MCNPX simulation results showed that TRRT can accurately track the motion of the tumor and detect the WEL variations. Image quality was optimized by choosing proton energy, testing parameters of image reconstruction algorithm, and comparing to ground truth 4DCT. The future study will demonstrate the feasibility of using the time resolved proton radiography as an imaging tool for proton treatments of lung tumors. PMID:21626923

  11. Structural characteristics of hydrated protons in the conductive channels: effects of confinement and fluorination studied by molecular dynamics simulation.

    PubMed

    Zhang, Ning; Song, Yuechun; Ruan, Xuehua; Yan, Xiaoming; Liu, Zhao; Shen, Zhuanglin; Wu, Xuemei; He, Gaohong

    2016-09-21

    The relationship between the proton conductive channel and the hydrated proton structure is of significant importance for understanding the deformed hydrogen bonding network of the confined protons which matches the nanochannel. In general, the structure of hydrated protons in the nanochannel of the proton exchange membrane is affected by several factors. To investigate the independent effect of each factor, it is necessary to eliminate the interference of other factors. In this paper, a one-dimensional carbon nanotube decorated with fluorine was built to investigate the independent effects of nanoscale confinement and fluorination on the structural properties of hydrated protons in the nanochannel using classical molecular dynamics simulation. In order to characterize the structure of hydrated protons confined in the channel, the hydrogen bonding interaction between water and the hydrated protons has been studied according to suitable hydrogen bond criteria. The hydrogen bond criteria were proposed based on the radial distribution function, angle distribution and pair-potential energy distribution. It was found that fluorination leads to an ordered hydrogen bonding structure of the hydrated protons near the channel surface, and confinement weakens the formation of the bifurcated hydrogen bonds in the radial direction. Besides, fluorination lowers the free energy barrier of hydronium along the nanochannel, but slightly increases the barrier for water. This leads to disintegration of the sequential hydrogen bond network in the fluorinated CNTs with small size. In the fluorinated CNTs with large diameter, the lower degree of confinement produces a spiral-like sequential hydrogen bond network with few bifurcated hydrogen bonds in the central region. This structure might promote unidirectional proton transfer along the channel without random movement. This study provides the cooperative effect of confinement dimension and fluorination on the structure and hydrogen

  12. Study of anisotropy in nuclear magnetic resonance relaxation times of water protons in skeletal muscle.

    PubMed Central

    Kasturi, S R; Chang, D C; Hazlewood, C F

    1980-01-01

    The anisotropy of the spin-lattice relaxation time (T1) and the spin-spin relaxation times (T2) of water protons in skeletal muscle tissue have been studied by the spin-echo technique. Both T1 and T2 have been measured for the water protons of the tibialis anterior muscle of mature male rats for theta = 0, 55, and 90 degrees, where theta is the orientation of the muscle fiber with respect to the static field. The anisotropy in T1 and T2 has been measured at temperatures of 28, -5 and -10 degrees C. No significant anisotropy was observed in the T1 of the tissue water, while an average anisotropy of approximately 5% was observed in T2 at room temperature. The average anisotropy of T2 at -5 and -10 degrees C was found to be approximately 2 and 1.3%, respectively. PMID:6266530

  13. Fundamental studies for the proton polarization technique in neutron protein crystallography.

    PubMed

    Tanaka, Ichiro; Kusaka, Katsuhiro; Chatake, Toshiyuki; Niimura, Nobuo

    2013-11-01

    The isotope effect in conventional neutron protein crystallography (NPC) can be eliminated by the proton polarization technique (ppt). Furthermore, the ppt can improve detection sensitivity of hydrogen (relative neutron scattering length of hydrogen) by approximately eight times in comparison with conventional NPC. Several technical difficulties, however, should be overcome in order to perform the ppt. In this paper, two fundamental studies to realise ppt are presented: preliminary trials using high-pressure flash freezing has shown the advantage of making bulk water amorphous without destroying the single crystal; and X-ray diffraction and liquid-chromatography/mass-spectrometry analyses of standard proteins after introducing radical molecules into protein crystals have shown that radical molecules could be distributed non-specifically around proteins, which is essential for better proton polarization. PMID:24121348

  14. Fundamental studies for the proton polarization technique in neutron protein crystallography

    PubMed Central

    Tanaka, Ichiro; Kusaka, Katsuhiro; Chatake, Toshiyuki; Niimura, Nobuo

    2013-01-01

    The isotope effect in conventional neutron protein crystallography (NPC) can be eliminated by the proton polarization technique (ppt). Furthermore, the ppt can improve detection sensitivity of hydrogen (relative neutron scattering length of hydrogen) by approximately eight times in comparison with conventional NPC. Several technical difficulties, however, should be overcome in order to perform the ppt. In this paper, two fundamental studies to realise ppt are presented: preliminary trials using high-pressure flash freezing has shown the advantage of making bulk water amorphous without destroying the single crystal; and X-ray diffraction and liquid-chromatography/mass-spectrometry analyses of standard proteins after introducing radical molecules into protein crystals have shown that radical molecules could be distributed non-specifically around proteins, which is essential for better proton polarization. PMID:24121348

  15. A study on the microstructure and mechanical property of proton irradiated A508-3 steel

    NASA Astrophysics Data System (ADS)

    Li, Xiao-hong; Lei, Jing; Shu, Guo-gang; Wan, Qiang-mao

    2015-05-01

    Transmission electron microscopy and the nanoindentation technique were employed to study the dislocation loops and hardening induced in proton irradiated A508-3 steel. The A508-3 steel specimens were irradiated to the dose of 0.054, 0.163, 0.271 dpa at room temperature (RT), 0.163 pa at 250 °C and 0.163, 0.271 dpa at 290 °C. The effect of dose and temperature on the dislocation loops and irradiation hardening was investigated. The results indicated that the dislocation loops were formed in proton irradiated A508-3 steel. The size and number density generally increased with increasing dose at RT. When the irradiation temperature changed from RT to 290 °C, the loop size increased and the loop number density decreased. The irradiation hardening increased with dose. The effect of temperature on the irradiation induced hardening was discussed.

  16. Proton transfer in the [phenol-NH3]+ system: An experimental and ab initio study

    NASA Astrophysics Data System (ADS)

    Kim, Ho-Tae; Green, Richard J.; Qian, Jun; Anderson, Scott L.

    2000-04-01

    Mass-analyzed threshold ionization (MATI) has been used to prepare phenol cations in selected vibrational states, including the ground state. Reactions of ground state C6H5OH+ with ND3, studied in a guided ion-beam apparatus, are reported, along with related ab initio calculations. This paper focuses on the energetics and product branching in the proton transfer (PT) channel. Based on thermochemistry in the literature, combined with calculations of the intracomplex PT barrier, PT was expected to make up a large fraction of the total reactive scattering. Experimentally, it is found that PT has a small cross section with clear threshold behavior, and the conclusion is that the PT reaction is endoergic by 4.5±1 kcal/mole. Assuming that NH3 has a proton affinity of 204.0 kcal/mole, this results in a proton affinity for phenoxy radical of 208.7 kcal/mole, and a neutral PhO-H bond energy of 91.1 kcal/mole. The results are used to reinterpret previous dissociative photoionization studies of phenol-ammonia complexes.

  17. The effects of energetic proton bombardment on polymeric materials: Experimental studies and degradation models

    NASA Technical Reports Server (NTRS)

    Coulter, D. R.; Gupta, A.; Smith, M. V.; Fornes, R. E.

    1986-01-01

    This report describes 3 MeV proton bombardment experiments on several polymeric materials of interest to NASA carried out on the Tandem Van De Graff Accelerator at the California Institute of Technology's Kellogg Radiation Laboratory. Model aromatic and aliphatic polymers such as poly(1-vinyl naphthalene) and poly(methyl methacrylate), as well as polymers for near term space applications such as Kapton, Epoxy and Polysulfone, have been included in this study. Chemical and physical characterization of the damage products have been carried out in order to develop a model of the interaction of these polymers with the incident proton beam. The proton bombardment methodology developed at the Jet Propulsion Laboratory and reported here is part of an ongoing study on the effects of space radiation on polymeric materials. The report is intended to provide an overview of the mechanistic, as well as the technical and experimental, issues involved in such work rather than to serve as an exhaustive description of all the results.

  18. Proton Donor/acceptor Propensities of Ammonia: Rotational Studies of its Molecular Complexes with Organic Molecules

    NASA Astrophysics Data System (ADS)

    Giuliano, Barbara M.; Maris, Assimo; Melandri, Sonia; Favero, Laura B.; Evangelisti, Luca; Caminati, Walther

    2009-06-01

    We studied the rotational spectra of the adducts of ammonia with several organic molecules, namely tert-butanol, glycidol, ethyl alcohol, anisol and 1,4-difluorobenzene. The adducts with glycidol and ethanol have been observed for both conformers of the substrate molecule. Based on the rotational and ^{14}N quadrupole coupling constants of the various complexes, we found a considerably different behaviour of ammonia, with respect to water, in its proton donor/acceptor double role. In the interaction with the three alcohol molecules, NH_{3} acts as a proton acceptor and the OH groups as a proton donor. However, in the case of glycidol-NH_{3}, a secundary N-H\\cdotsO interaction occurrs between ammonia and the ether oxygen. This interaction generates a sizable V_{3} barrier to the internal rotation of the NH_{3} moiety, while NH_{3} undergoes a free rotation in tert-butanol-NH_{3} and in ethanol-NH_{3}. As to the anisole-NH_{3} and 1,4-difluorobenzene-NH_{3} complexes, the NH_{3} group explicits its double proton donor/acceptor role, although through two weak (C_{Me}-H\\cdotsN and N-H\\cdotsπ) H-bonds. There is, however, an important difference between the two complexes, because in the first one NH_{3} lies out of the aromatic plane, while in the second one it is in the plane of the aromatic ring. B. M. Giuliano, M. C. Castrovilli, A. Maris, S. Melandri, W. Caminati and E. A. Cohen, Chem.Phys.Lett., 2008, 463, 330 B. M. Giuliano, S. Melandri, A. Maris, L. B. Favero and W. Caminati, Angew.Chem.Int.Ed., 2009, 48, 1102

  19. Enhanced radiobiological effects at the distal end of a clinical proton beam: in vitro study

    PubMed Central

    Matsumoto, Yoshitaka; Matsuura, Taeko; Wada, Mami; Egashira, Yusuke; Nishio, Teiji; Furusawa, Yoshiya

    2014-01-01

    In the clinic, the relative biological effectiveness (RBE) value of 1.1 has usually been used in relation to the whole depth of the spread-out Bragg-peak (SOBP) of proton beams. The aim of this study was to confirm the actual biological effect in the SOBP at the very distal end of clinical proton beams using an in vitro cell system. A human salivary gland tumor cell line, HSG, was irradiated with clinical proton beams (accelerated by 190 MeV/u) and examined at different depths in the distal part and the center of the SOBP. Surviving fractions were analyzed with the colony formation assay. Cell survival curves and the survival parameters were obtained by fitting with the linear–quadratic (LQ) model. The RBE at each depth of the proton SOBP compared with that for X-rays was calculated by the biological equivalent dose, and the biological dose distribution was calculated from the RBE and the absorbed dose at each position. Although the physical dose distribution was flat in the SOBP, the RBE values calculated by the equivalent dose were significantly higher (up to 1.56 times) at the distal end than at the center of the SOBP. Additionally, the range of the isoeffective dose was extended beyond the range of the SOBP (up to 4.1 mm). From a clinical point of view, this may cause unexpected side effects to normal tissues at the distal position of the beam. It is important that the beam design and treatment planning take into consideration the biological dose distribution. PMID:24824674

  20. Fast-neutron spectroscopy studies using induced-proton tracks in PADC track detectors

    NASA Astrophysics Data System (ADS)

    El-Sersy, A. R.; Eman, S. A.

    2010-06-01

    In this work, a simple and adequate method for fast-neutron spectroscopy is proposed. This method was performed by free-in-air fast-neutron irradiation of CR-39 Nuclear Track Detectors (NTD) using an Am-Be source. Detectors were then chemically etched to remove few layers up to a thickness of 6.25 μm. By using an automatic image analyzer system for studying the registration of the induced-proton tracks in the NTD, the obtained data were analyzed via two tracks shapes. In the first one, the elliptical tracks were eliminated from the calculation and only the circular ones were considered in developing the response function. In the second method all registered tracks were considered and the corresponding response function was obtained. The rate of energy loss of the protons as a function of V[(d E/d X) - V] was calculated using the Monte Carlo simulation. The induced-proton energy was extracted from the corresponding d E/d X in NTD using a computer program based on the Bethe-Bloch function. The energy of the incident particles was up to few hundred MeV/nucleon. The energy of the interacting neutrons was then estimated by means of the extracted induced-proton energies and the scattering angle. It was found that the present resulting energy distribution of the fast-neutron spectrum from the Am-Be source was similar to that given in the literature where an average neutron energy of 4.6MeV was obtained.

  1. Proton pump inhibition prevents gastrointestinal bleeding in ultramarathon runners: a randomised, double blinded, placebo controlled study

    PubMed Central

    Thalmann, M; Sodeck, G H; Kavouras, S; Matalas, A; Skenderi, K; Yannikouris, N; Domanovits, H

    2006-01-01

    Background Ultra‐endurance running is emerging as a popular sport in Western industrialised countries. Gastrointestinal bleeding has been reported to be an adverse effect in these runners. Objective To see if the oral administration of a proton pump inhibitor would reduce the incidence of gastrointestinal bleeding in an ultramarathon. Methods In a randomised, double blinded, placebo controlled study, a prophylactic regimen of three days of an oral proton pump inhibitor (pantoprazole 20 mg) was tested in healthy athletes participating in the Spartathlon ultramarathon. The incidence of gastrointestinal bleeding was assessed by a stool guaiac test. Results Results were obtained for 70 healthy volunteers. The data for 20 of 35 runners in the intervention group and 17 of 35 runners in the placebo group were entered into the final analysis. At the end of the ultramarathon, two subjects in the intervention group and 12 in the placebo group had positive stool guaiac tests (risk difference 0.86; 95% confidence interval 0.45 to 0.96; p  =  0.001). Conclusion A short prophylactic regimen of oral proton pump inhibition can successfully decrease the incidence of gastrointestinal bleeding in participants in an ultramarathon. PMID:16556794

  2. Intrinsic Proton NMR Studies of Mg(OH)2 and Ca(OH)2

    NASA Astrophysics Data System (ADS)

    Itoh, Yutaka; Isobe, Masahiko

    2016-09-01

    We studied the short proton free induction decay signals and the broad 1H NMR spectra of Mg(OH)2 and Ca(OH)2 powders at 77-355 K and 42 MHz using pulsed NMR techniques. Using a Gaussian-type back extrapolation procedure for the obscured data of the proton free induction decay signals, we obtained more precise values of the second moments of the Fourier-transformed broad NMR spectra than those in a previous report [Y. Itoh and M. Isobe, J. Phys. Soc. Jpn. 84, 113601 (2015)] and compared with the theoretical second moments. The decrease in the second moment could not account for the large decrease in the magnitude of the intrinsic proton spin-lattice relaxation rate 1/T1 from Mg(OH)2 to Ca(OH)2. The analysis of 1/T1 ∝ exp(-Eg/kBT) with Eg ˜ 0.01 eV points to a local hopping mechanism, and that of 1/T1 ∝ Tn with n ˜ 0.5 points to an anharmonic rattling mechanism.

  3. Systematic Study of Technetium Production by Proton-Induced Reactions on Molybdenum

    NASA Astrophysics Data System (ADS)

    Lamere, Edward; Gilardy, Gwenaelle; Meisel, Zach; Moran, Michael; Skulski, Michael; Couder, Manoel

    2015-10-01

    Recent shortages in the world-wide supply of 99mTc have sparked interest in developing alternative production methods which do not rely on fission based 99Mo. The direct production of 99mTc from proton induced reactions on enriched 100Mo targets is one such approach. With this approach, 99mTc must be chemically extracted from the irradiated target and therefore radiopharmaceuticals will contain a mixture of all Tc-species produced from the proton bombardment. Commercial viability of cyclotron-produced 99mTc will depend on a number of factors including, production yield, radiochemical purity, and specific activity. Reactions on trace impurities in the targets has been shown to impact these factors dramatically. Precise cross-section measurements for not just the main reaction, 99mTc(p,2n), but for all Mo + p reactions that lead to Tc or Mo species are required for proper assessment of this 99mTc production technique. We will introduce a systematic study of proton-induced reactions on 92, 94-98, 100 Mo currently being performed at the University of Notre Dame. First results of 96Mo + p reactions will be presented. NRC-HQ-12-G-38-0073.

  4. Comprehensive studies on an overall proton transfer cycle of the ortho-green fluorescent protein chromophore.

    PubMed

    Hsieh, Cheng-Chih; Chou, Pi-Tai; Shih, Chun-Wei; Chuang, Wei-Ti; Chung, Min-Wen; Lee, Junghwa; Joo, Taiha

    2011-03-01

    -1500 cm(-1) are assigned to the phenyl in-plane breathing motions of the trans-proton transfer tautomer. Monitored by the nanosecond transient absorption, the 580 nm transient undergoes a ∼7.7 μs decay constant, accompanied by the growth of a new ∼500 nm band. The latter is assigned to a deprotonated tautomer species, which then undergoes the ground-state reverse proton recombination to the original o-HBDI in ∼50 μs, achieving an overall, reversible proton transfer cycle. This assignment is unambiguously supported by pump-probe laser induced fluorescence studies. On these standpoints, a comparison of photophysical properties among o-HBDI, p-HBDI, and wild-type GFP is discussed in detail. PMID:21323314

  5. The study of the proton-proton collisions at the beam momentum 1581 MeV/c

    NASA Astrophysics Data System (ADS)

    Ermakov, K. N.; Medvedev, V. I.; Nikonov, V. A.; Rogachevsky, O. V.; Sarantsev, A. V.; Sarantsev, V. V.; Sherman, S. G.

    2014-06-01

    The new data on the elastic pp and single-pion production reaction pp → pnπ + taken at the incident proton momentum 1581 MeV/ c are presented. To extract contributions of the leading partial waves the single-pion production data are analyzed in the framework of the event-by-event maximum-likelihood method together with pp → ppπ + data measured earlier and the pp → pnπ + data taken at 1628 MeV/ c. The analysis shows that at 1581 MeV/ c the largest contributions stem from the 3 P 2, 3 P 1, 3 P 0 and 3 F 2 initial partial waves. From these partial waves we also deduce contributions for the production of the Δ(1232) and N(1440) states.

  6. Proton Decay Studies of the Light Lu, Tm and Ho Isotopes

    SciTech Connect

    Akovali, Y.; Batchelder, J.C.; Bingham, C.R.; Davinson, T.; Ginter, T.N.; Gross, C.J.; Grzywacz, R.; Hamilton, J.H.; Janas, Z.; Karny, M.; Kim, S.H.; MacDonald, B.D.; Mas, J.F.; McConnell, J.W.; Piechaczek, A.; Ressler, J.J.; Rykaczewski, K.; Slinger, R.C.; Szerypo, J.; Toth, K.S.; Weintraub, W.; Woods, P.J.; Yu, C.-H.; Zganjar, E.F.

    1998-10-15

    A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {micro}sec. In this paper the authors present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu.

  7. A study of molecular dynamics and freezing phase transition in tissues by proton spin relaxation.

    PubMed Central

    Rustgi, S N; Peemoeller, H; Thompson, R T; Kydon, D W; Pintar, M M

    1978-01-01

    Muscle, spleen, and kidney tissues from 4-wk-old C57 black mice were studied by proton magnetic resonance. Spin-lattice relaxation times at high fields and in the rotating frame, as well as the spin-spin relaxation times, are reported as a function of temperature in the liquid and frozen phase. Motions of large molecules and of water molecules and their changes at the freezing phase transition are studied. The shortcomings of the two-state fast-exchange relaxation model are discussed. PMID:667294

  8. Proton decay studies of the light Lu, Tm and Ho isotopes

    SciTech Connect

    Batchelder, J. C.; Bingham, C. R.; Gross, C. J.; Grzywacz, R.; Rykaczewski, K.; Toth, K. S.; Zganjar, E. F.; Akovali, Y.; Davinson, T.; Ginter, T. N.

    1999-09-02

    A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {mu}sec. In this paper we present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu. (c) 1999 American Institute of Physics.

  9. Radioactive halos and ion microprobe measurement of Pb isotope ratios

    NASA Technical Reports Server (NTRS)

    Gentry, R. V.

    1974-01-01

    This investigation was to obtain, if possible, the Pb isotope ratios of both lunar and meteoritic troilite grains by utilizing ion microprobe techniques. Such direct in situ measurement of Pb isotope ratios would eliminate contamination problems inherent in wet chemistry separation procedures, and conceivably determine whether lunar troilite grains were of meteoritic origin. For comparison purposes two samples of meteoritic troilite were selected (one from Canyon Diablo) for analysis along with two very small lunar troilite grains (approximately 50-100 microns). It was concluded that the ion microprobe as presently operating, does not permit the in situ measurement of Pb isotope ratios in lunar or meteoritic troilite. On the basis of these experiments no conclusions could be drawn as to the origin of the lunar troilite grains.

  10. High brightness sources for MeV microprobe applications

    SciTech Connect

    Read, P.M.; Alton, G.D.; Maskrey, J.T.

    1987-01-01

    State of the art MeV ion microprobe facilities are now approaching current density limitations on targets imposed by the fundamental nature of conventional gaseous ion sources. With a view to addressing this problem efforts are under way which have the ultimate objective of developing high brightness Li liquid metal ion sources suitable for MeV ion microprobe applications. Prototype Li/sup +/ and Ga/sup +/ liquid metal ion sources have been designed, fabricated and are undergoing preliminary testing. This paper describes the first total emittance and brightness measurements of a Ga liquid metal ion source. The effect of the geometry of the ion extraction system is investigated and the brightness data are compared to those of a radio frequency ion source.

  11. Wavelength dispersive μPIXE setup for the ion microprobe

    NASA Astrophysics Data System (ADS)

    Fazinić, S.; Božičević Mihalić, I.; Tadić, T.; Cosic, D.; Jakšić, M.; Mudronja, D.

    2015-11-01

    We have developed a small wavelength dispersive X-ray spectrometer to explore the possibility of performing chemical speciation on microscopic samples utilizing focused ion beams available at the Rudjer Boskovic Institute ion microprobe. Although PIXE spectra are in principle chemically invariant, small influence of chemical effects could be observed even with Si(Li) or SDD detectors. Such chemical effects can be clearly seen with high resolution crystal X-ray spectrometers having energy resolution of several eV. A dedicated vacuum chamber, housing the diffraction crystal, sample holder and CCD X-ray detector, was constructed and positioned behind the main ion microprobe vacuum chamber. Here we will briefly describe the spectrometer, and illustrate its capabilities on measured K X-ray spectra of selected sulfur compounds. We will also demonstrate its abilities to resolve K and M X-ray lines irresolvable by solid state ED detectors usually used in PIXE.

  12. Study of proton acceleration at the target front surface in laser-solid interactions by neutron spectroscopy

    SciTech Connect

    Youssef, A.; Kodama, R.; Tampo, M.

    2006-03-15

    Proton acceleration inside solid LiF and CH-LiF targets irradiated by a 450-fs, 20-J, 1053-nm laser at an intensity of 3x10{sup 18} W/cm{sup 2} has been studied via neutron spectroscopy. Neutron spectra produced through the {sup 7}Li(p,n){sup 7}Be reaction that occurs between accelerated protons, at the front surface, and background {sup 7}Li ions inside the target. From measured and calculated spectra, by three-dimensional Monte Carlo code, the maximum energy, total number, and slope temperature of the accelerated protons are investigated. The study indicates that protons originate at the front surface and are accelerated to a maximum energy that is reasonably consistent with the calculated one due to the ponderomotive force.

  13. Microprobe analyses of glasses and minerals from Luna-16 soil

    NASA Technical Reports Server (NTRS)

    Brown, R. W.; Harmon, R. S.; Jakes, P.; Reid, A. M.; Ridley, W. I.; Warner, J. L.

    1971-01-01

    Electron microprobe analyses are presented for nine elements in 250 glasses and 434 pyroxenes, eight elements in 113 olivines, and six elements in 354 feldspars, 35 spinels, and 159 ilmenites. All grains are from the 125-425 micron fraction of horizon A and horizon D soil from the Luna 16 sample. A norm is presented for each glass analysis and the structural formula is calculated for each mineral analysis.

  14. Studying the proton 'radius' puzzle with μp elastic scattering

    SciTech Connect

    Gilman, R.

    2013-11-07

    The disagreement between the proton radius determined from muonic hydrogen and from electronic measurements is called the proton radius puzzle. The resolution of the puzzle remains unclear and appears to require new experimental results. An experiment to measure muon-proton elastic scattering is presented here.

  15. Production of a positron microprobe using a transmission remoderator.

    PubMed

    Fujinami, Masanori; Jinno, Satoshi; Fukuzumi, Masafumi; Kawaguchi, Takumi; Oguma, Koichi; Akahane, Takashi

    2008-01-01

    A production method for a positron microprobe using a beta+-decay radioisotope (22Na) source has been investigated. When a magnetically guided positron beam was extracted from the magnetic field, the combination of an extraction coil and a magnetic lens enabled us to focus the positron beam by a factor of 10 and to achieve a high transport efficiency (71%). A 150-nm-thick Ni(100) thin film was mounted at the focal point of the magnetic lens and was used as a remoderator for brightness enhancement in a transmission geometry. The remoderated positrons were accelerated by an electrostatic lens and focused on the target by an objective magnetic lens. As a result, a 4-mm-diameter positron beam could be transformed into a microprobe of 60 microm or less with 4.2% total efficiency. The S parameter profile obtained by a single-line scan of a test specimen coincided well with the defect distribution. This technique for a positron microprobe is available to an accelerator-based high-intensity positron source and allows 3-dimensional vacancy-type defect analysis and a positron source for a transmission positron microscope. PMID:18187852

  16. Neurochemical alterations in adolescent chronic marijuana smokers: a proton MRS study.

    PubMed

    Prescot, Andrew P; Locatelli, Allison E; Renshaw, Perry F; Yurgelun-Todd, Deborah A

    2011-07-01

    Converging evidence from neuroimaging and neuropsychological studies indicates that heavy marijuana use is associated with cingulate dysfunction. However, there has been limited human data documenting in vivo biochemical brain changes after chronic marijuana exposure. Previous proton magnetic resonance spectroscopy studies have demonstrated reduced basal ganglia glutamate and dorsolateral prefrontal cortex N-acetyl aspartate levels in adult chronic marijuana users. Similar studies have not been reported in adolescent populations. The present study used proton magnetic resonance spectroscopy to determine whether reductions in glutamate, N-acetyl aspartate and/or other proton metabolite concentrations would be found in the anterior cingulate cortex (ACC) of adolescent marijuana users compared with non-using controls. Adolescent marijuana users (N=17; average age 17.8 years) and similarly aged healthy control subjects (N=17; average age 16.2 years) were scanned using a Siemens 3T Trio MRI system. Proton magnetic resonance spectroscopy data were acquired from a 22.5 mL voxel positioned bilaterally within the ACC. Spectra were fitted using commercial software and all metabolite integrals were normalized to the scaled unsuppressed water integral. Analysis of variance and analysis of covariance were performed to compare between-group metabolite levels. The marijuana-using cohort showed statistically significant reductions in anterior cingulate glutamate (-15%, p<0.01), N-acetyl aspartate (-13%, p=0.02), total creatine (-10%, p<0.01) and myo-inositol (-10%, p=0.03). Within-voxel tissue-type segmentation did not reveal any significant differences in gray/white matter or cerebrospinal fluid content between the two groups. The reduced glutamate and N-acetyl aspartate levels in the adolescent marijuana-using cohort are consistent with precedent human (1)H MRS data, and likely reflect an alteration of anterior cingulate glutamatergic neurotransmission and neuronal integrity

  17. Aperture studies for the AP2 anti-proton Line at Fermilab

    SciTech Connect

    Reichel, Ina; Zisman, Michael; Placidi, Massimo

    2003-12-05

    The AP2 beamline transports anti-protons from the production target to the Debuncher ring. For many years the observed aperture has been smaller than that estimated from linear, on-energy optics. We have investigated possible reasons for the aperture restriction and have identified several possible sources, including residual vertical dispersion from alignment errors and chromatic effects due to very large chromatic lattice functions. We discuss the possible sources, suggest some remedies, and propose specific studies, where needed, to evaluate suspected problems.

  18. Effect of magnetic quadrupole lens alignment on a nuclear microprobe resolution

    NASA Astrophysics Data System (ADS)

    Kolinko, S. V.; Ponomarev, A. G.

    2016-04-01

    The paper reports the research trends in developing probe-forming systems with high demagnification and analysis factors that limit a nuclear microprobe resolution. Parasitic aberrations caused by tilts and offsets of magnetic quadrupoles are studied in terms of their effect on probe parameters on a target. The most common arrangements of probe-forming systems such as a triplet and "Russian quadruplet" with separated geometry are considered. The accuracy prerequisites for the positioning of the quadrupoles are defined, and practical guidelines for alignment of probe-forming systems with high demagnification factors are suggested.

  19. Radiation protection studies for a high-power 160 MeV proton linac

    NASA Astrophysics Data System (ADS)

    Mauro, Egidio; Silari, Marco

    2009-07-01

    CERN is presently designing a new chain of accelerators to replace the present Proton Synchrotron (PS) complex: a 160 MeV room-temperature H - linac (Linac4) to replace the present 50 MeV proton linac injector, a 3.5 GeV Superconducting Proton Linac (SPL) to replace the 1.4 GeV PS Booster (PSB) and a 50 GeV synchrotron (named PS2) to replace the 26 GeV PS. Linac4 has been funded and the civil engineering work started in October 2008, whilst the SPL is in an advanced stage of design. Beyond injecting into the future 50 GeV PS, the ultimate goal of the SPL is to generate a 4 MW beam for the production of intense neutrino beams. The radiation protection design is driven by the latter requirement. This work summarizes the radiation protection studies conducted for Linac4. FLUKA Monte Carlo simulations, complemented by analytical estimates, were performed to evaluate the propagation of neutrons through the waveguide, ventilation and cable ducts placed along the accelerator, to estimate the radiological impact of the accelerator in its low-energy section, where the access area is located, and to calculate the induced radioactivity in the air and in the components of the accelerator. The latter study is particularly important for maintenance interventions and final disposal of radioactive waste. Two possible layouts for the CCDTL section of the machine were considered in order to evaluate the feasibility, from the radiological standpoint, of replacing electromagnetic quadrupoles with permanent magnet quadrupoles with a high content of cobalt.

  20. Pulse radiolytic study of the acid dissociation of OH protons in radicals related to salicylic acid

    SciTech Connect

    Sun, Q.; Schuler, R.H.

    1987-08-13

    The deprotonation of carboxylated benzosemiquinone radicals prepared by pulse radiolytic oxidation of dihydroxybenzoic acids has been examined by time-resolved absorption spectrophotometry. The pK/sub a/ for dissociation of the OH proton in 3-carboxyl-1,4-benzosemiquinone is found to be 6.47 or 2.4 units higher than that in the unsubstituted radical. This pK/sub a/ is, however, well below that of the OH proton in salicyclic acid (13.6) so that hydrogen bonding is appreciably decreased by the delocalization of the unpaired spin in this radical. Protonation of the basic form of the radical occurs at the diffusion-controlled rate. The rate constant for deprotonation by OH/sup -/ is relatively low, 4.7 X 10/sup 7/ M/sup -1/ s/sup -1/, so that reaction with base becomes important only above pH 10. As a result this radical provides an excellent system for studying acid-base equilibration processes in near neutral solutions. Azide ion is shown to be an efficient catalyst which allows the acid-base equilibrium to be examined on the 10-..mu..s time scale. Deprotonation is also catalyzed by the dihydroxybenzoic acid used as the radical source. Analogous studies on 4-carboxy-1,3-benzosemiquinone give the pK/sub a/ as 7.9. In spite of this high pK/sub a/, which indicates the rate constant for spontaneous dissociation of this radical to be > 10/sup 3/ s/sup -1/, the rate constant for deprotonation by OH/sup -/, 4.9 X 10/sup 8/ M/sup -1/ s/sup -1/, is considerably higher than in the case of 3-carboxy-1,4-benzosemiquinone.

  1. Studies of the reduction and protonation behavior of tetraheme cytochromes using atomic detail.

    PubMed

    Teixeira, Vitor H; Soares, Cláudio M; Baptista, António M

    2002-01-01

    A comparative study of tetraheme cytochrome c3 molecules from several species was carried out using recently developed theoretical methods based on continuum electrostatics. The binding joint equilibrium of electrons and protons was simulated, revealing the complete thermodynamic aspects of electron-proton coupling in these molecules. The method yields excellent accuracy in terms of midpoint potentials, giving the correct reduction orders in all molecules examined, except for one heme site. The coupling between electrons and protons is shown to be present and significant at physiological pH in all cases. This phenomenon, known as the redox-Bohr effect, though of thermodynamic nature, is shown to have an intrinsic "dynamic" character at the molecular level (in the sense of the empty/occupied fluctuations at the microscopic level), with the binding states of redox and protonatable sites displaying both correlated averages and correlated fluctuations. The protonatable sites more directly involved in the redox-Bohr effect are identified using, among other properties, the statistical correlation between pairs of sites, which automatically reflects indirect effects mediated by other sites. Several sites are identified in this analysis. Propionate D of heme I seems to be the most interesting, generally showing a high correlation not only with its own heme, but also with heme II, corresponding to an indirect stabilization of the reduced forms of both hemes. Other interesting sites are the free histidines of two of the cytochromes and propionate D of heme IV, the latter being potentially associated with redox-induced structural changes. Among the set of cytochromes c3 analyzed in this study, significant differences are observed for several properties of the acidic cytochrome included in the set, from Desulfovibrio africanus, supporting the hypothesis of a different functional role. PMID:11862556

  2. Diffusion length damage coefficient and annealing studies in proton-irradiated InP

    NASA Technical Reports Server (NTRS)

    Hakimzadeh, Roshanak; Vargas-Aburto, Carlos; Bailey, Sheila G.; Williams, Wendell

    1993-01-01

    We report on the measurement of the diffusion length damage coefficient (K(sub L)) and the annealing characteristics of the minority carrier diffusion length (L(sub n)) in Czochralski-grown zinc-doped indium phosphide (InP), with a carrier concentration of 1 x 10(exp l8) cm(exp -3). In measuring K(sub L) irradiations were made with 0.5 MeV protons with fluences ranging from 1 x 10(exp 11) to 3 x 10(exp 13) cm(exp -2). Pre- and post-irradiation electron-beam induced current (EBIC) measurements allowed for the extraction of L(sub n) from which K(sub L) was determined. In studying the annealing characteristics of L(sub n) irradiations were made with 2 MeV protons with fluence of 5 x 10(exp 13) cm(exp -2). Post-irradiation studies of L(sub n) with time at room temperature, and with minority carrier photoinjection and forward-bias injection were carried out. The results showed that recovery under Air Mass Zero (AMO) photoinjection was complete. L(sub n) was also found to recover under forward-bias injection, where recovery was found to depend on the value of the injection current. However, no recovery of L(sub n) after proton irradiation was observed with time at room temperature, in contrast to the behavior of 1 MeV electron-irradiated InP solar cells reported previously.

  3. Experimental study of resolution of proton chemical shifts in solids: Combined multiple pulse NMR and magic-angle spinning

    SciTech Connect

    Ryan, L.M.; Taylor, R.E.; Paff, A.J.; Gerstein, B.C.

    1980-01-01

    High-resolution nuclear magnetic resonance spectra of protons in rigid, randomly oriented solids have been measured using combined homonuclear dipolar decoupling (via multiple pulse techniques) and attenuation of chemical shift anisotropies (via magic-angle sample spinning). Under those conditions, isotropic proton chemical shifts were recorded for a variety of chemical species, with individual linewidths varying from about 55 to 110 Hz (1--2 ppm). Residual line broadening was due predominately to (i) magnetic-field instability and inhomogeneity, (ii) unresolved proton--proton spin couplings, (iii) chemical shift dispersion, (iv) residual dipolar broadening, and (v) lifetime broadening under the multiple pulse sequences used. The magnitudes of those effects and the current limits of resolution for this experiment in our spectrometer have been investigated. The compounds studied included organic solids (4, 4'-dimethylbenzophenone, 2, 6-dimethylbenzoic acid, and aspirin), polymers (polystyrene and polymethylmethacrylate), and the vitrain portion of a bituminous coal.

  4. Monte Carlo study of radial energy deposition from primary and secondary particles for narrow and large proton beamlet source models

    NASA Astrophysics Data System (ADS)

    Peeler, Christopher R.; Titt, Uwe

    2012-06-01

    In spot-scanning intensity-modulated proton therapy, numerous unmodulated proton beam spots are delivered over a target volume to produce a prescribed dose distribution. To accurately model field size-dependent output factors for beam spots, the energy deposition at positions radial to the central axis of the beam must be characterized. In this study, we determined the difference in the central axis dose for spot-scanned fields that results from secondary particle doses by investigating energy deposition radial to the proton beam central axis resulting from primary protons and secondary particles for mathematical point source and distributed source models. The largest difference in the central axis dose from secondary particles resulting from the use of a mathematical point source and a distributed source model was approximately 0.43%. Thus, we conclude that the central axis dose for a spot-scanned field is effectively independent of the source model used to calculate the secondary particle dose.

  5. High-temperature annealing of proton irradiated beryllium - A dilatometry-based study

    NASA Astrophysics Data System (ADS)

    Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; Ghose, Sanjit; Savkliyildiz, Ilyas

    2016-08-01

    Ssbnd 200 F grade beryllium has been irradiated with 160 MeV protons up to 1.2 1020 cm-2 peak fluence and irradiation temperatures in the range of 100-200 °C. To address the effect of proton irradiation on dimensional stability, an important parameter in its consideration in fusion reactor applications, and to simulate high temperature irradiation conditions, multi-stage annealing using high precision dilatometry to temperatures up to 740 °C were conducted in air. X-ray diffraction studies were also performed to compliment the macroscopic thermal study and offer a microscopic view of the irradiation effects on the crystal lattice. The primary objective was to qualify the competing dimensional change processes occurring at elevated temperatures namely manufacturing defect annealing, lattice parameter recovery, transmutation 4He and 3H diffusion and swelling and oxidation kinetics. Further, quantification of the effect of irradiation dose and annealing temperature and duration on dimensional changes is sought. The study revealed the presence of manufacturing porosity in the beryllium grade, the oxidation acceleration effect of irradiation including the discontinuous character of oxidation advancement, the effect of annealing duration on the recovery of lattice parameters recovery and the triggering temperature for transmutation gas diffusion leading to swelling.

  6. X-ray microprobe measurements of the chemical compositions of ALH84001 carbonate globules

    SciTech Connect

    Flynn, G.J.; Sutton, S.R.; Keller, L.P.

    2004-01-28

    We measured minor element contents of carbonate from ALH84001 and report trends in tbe Ca, V, Mn and Sr in carbonate and the associated magnetite bands. McKay et al. suggested that carbonate globules in the ALH84001 meteorite from Mars contained evidence consistent with the development of bacterial life early in the history of Mars. This result provoked an extensive study of the ALH84001 meteorite. More recently Thomas-Keprta et al. have published a study showing that the magnetite associated with carbonate rims are of the size and shape produced by terrestrial bacteria. This paper has revived interest in ALH84001. The typical ALH84001 carbonate globule consists of four regions: a core of Fe-rich carbonate, a thin magnetite-rich band, a rim of Mn-rich carbonate, and another thin magnetite-rich band. Trace element analysis of each of these phases may allow us to address several important questions about these carbonates: (1) The origin of the magnetite-rich bands in the ALH84001 carbonate globules. If the magnetites are derived from the underlying carbonate through thermal decomposition (as proposed by Golden et al.), then we expect to see 'inherited' trace elements in these magnetite bands. (2) The origin of the rim carbonate, by determining whether the carbonate in the core has the same trace elements as the rim carbonates. (3) The age of the rim carbonate. Borg et al. dated the formation of the rim carbonate using the Rb/Sr chronometer. Borg et al. performed their measurements on an aliquot of what they called a high-Rb, low-Sr carbonate separate from the rim. We previously measured the trace element contents of chips from core and rim carbonates from an ALH84001 carbonate globule using an X-Ray Microprobe on Beamline X26A at the National Synchrotron Light Source. These measurements showed the rim carbonate had a very low Rb content, with Sr>>Rb, inconsistent with the {approx}5 ppm Rb reported by Borg et al. in the sample they dated by the Rb/Sr chronometer. The

  7. The study on changes of rectum area in proton prostate cancer therapy

    NASA Astrophysics Data System (ADS)

    Kim, S. Y.; Lee, H. K.; Shin, H. W.; Kim, S. C.; Cho, J. H.

    2015-10-01

    The purpose of this study is to determine the changes in the rectum area during treatment and to identify the rectum area within the given field of view in order to reproduce the same pose as that presented during therapy planning to properly deliver the planned dose to the prostate. We obtained digitally reconstructed radiographs after planning treatment for 30 patients out of all patients who had been subjected to proton prostate cancer therapy from August 2012 to November 2014 at this hospital. We then obtained an image using a digital imaging positioning system (DIPS) on the first day of treatment. When planning the digitally reconstructed radiograph treatment, we determined the change in size of the rectum between the actual treatment and treatment planning by measuring the cross section of the rectum and the cross section on the image from the DIPS. The results indicated that the rectum area in the digitally reconstructed radiograph taken during treatment planning and the rectum area obtained from the DIPS image during treatment were different. As a consequence, when region targeted for proton treatment of prostate cancer does not maintain a constant volume, the position of the prostate does not receive an adequate dose due to such changes. Therefore, the results of this study will be useful to determine the corresponding volume during a prostate treatment plan.

  8. Experimental and Computational Studies of the Formation Mechanism of Protonated Interstellar Diazines

    NASA Astrophysics Data System (ADS)

    Wang, Zhe-Chen; Cole, Callie A.; Snow, Theodore P.; Bierbaum, Veronica M.

    2015-01-01

    Studies of interstellar chemistry have grown in number and complexity by both observations and laboratory measurements, and nitrogen-containing aromatics have been implicated as important interstellar molecules. In this paper, the gas-phase collision induced dissociation (CID) processes of protonated pyridazine (1,2-diazine), pyrimidine (1,3-diazine), and pyrazine (1,4-diazine) cations (C4H5N2 +) are investigated in detail both experimentally and theoretically. The major neutral loss for all three CID processes is HCN, leading to the formation of C3H4N+ isomers; our density functional theory (DFT) calculations support and elucidate our experimental results. The formation of C3H4N+ isomers from the reaction of abundant interstellar acrylonitrile (CH2CHCN) and H+is also studied employing DFT calculations. Our results lead to a novel mechanism for interstellar protonated diazine formation from the consecutive reactions of CH2CHCN+ H+ + HCN. Moreover, our results motivate the continuing search for interstellar C3H4N+ isomers as well as polycyclic aromatic N-containing hydrocarbons (PANHs).

  9. EXPERIMENTAL AND COMPUTATIONAL STUDIES OF THE FORMATION MECHANISM OF PROTONATED INTERSTELLAR DIAZINES

    SciTech Connect

    Wang, Zhe-Chen; Cole, Callie A.; Bierbaum, Veronica M.; Snow, Theodore P.

    2015-01-10

    Studies of interstellar chemistry have grown in number and complexity by both observations and laboratory measurements, and nitrogen-containing aromatics have been implicated as important interstellar molecules. In this paper, the gas-phase collision induced dissociation (CID) processes of protonated pyridazine (1,2-diazine), pyrimidine (1,3-diazine), and pyrazine (1,4-diazine) cations (C{sub 4}H{sub 5}N{sub 2} {sup +}) are investigated in detail both experimentally and theoretically. The major neutral loss for all three CID processes is HCN, leading to the formation of C{sub 3}H{sub 4}N{sup +} isomers; our density functional theory (DFT) calculations support and elucidate our experimental results. The formation of C{sub 3}H{sub 4}N{sup +} isomers from the reaction of abundant interstellar acrylonitrile (CH{sub 2}CHCN) and H{sup +}is also studied employing DFT calculations. Our results lead to a novel mechanism for interstellar protonated diazine formation from the consecutive reactions of CH{sub 2}CHCN+ H{sup +} + HCN. Moreover, our results motivate the continuing search for interstellar C{sub 3}H{sub 4}N{sup +} isomers as well as polycyclic aromatic N-containing hydrocarbons (PANHs)

  10. Validation of a track repeating algorithm for intensity modulated proton therapy: clinical cases study

    NASA Astrophysics Data System (ADS)

    Yepes, Pablo P.; Eley, John G.; Liu, Amy; Mirkovic, Dragan; Randeniya, Sharmalee; Titt, Uwe; Mohan, Radhe

    2016-04-01

    Monte Carlo (MC) methods are acknowledged as the most accurate technique to calculate dose distributions. However, due its lengthy calculation times, they are difficult to utilize in the clinic or for large retrospective studies. Track-repeating algorithms, based on MC-generated particle track data in water, accelerate dose calculations substantially, while essentially preserving the accuracy of MC. In this study, we present the validation of an efficient dose calculation algorithm for intensity modulated proton therapy, the fast dose calculator (FDC), based on a track-repeating technique. We validated the FDC algorithm for 23 patients, which included 7 brain, 6 head-and-neck, 5 lung, 1 spine, 1 pelvis and 3 prostate cases. For validation, we compared FDC-generated dose distributions with those from a full-fledged Monte Carlo based on GEANT4 (G4). We compared dose-volume-histograms, 3D-gamma-indices and analyzed a series of dosimetric indices. More than 99% of the voxels in the voxelized phantoms describing the patients have a gamma-index smaller than unity for the 2%/2 mm criteria. In addition the difference relative to the prescribed dose between the dosimetric indices calculated with FDC and G4 is less than 1%. FDC reduces the calculation times from 5 ms per proton to around 5 μs.

  11. Neutrino oscillations with a proton driver upgrade and an off-axis detector: A Case study

    SciTech Connect

    Barenboim, Gabriela; De Gouvea, Andre; Szleper, Michal; Velasco, Mayda

    2002-04-01

    We study the physics capabilities of the NuMI beamline with an off-axis highly-segmented iron scintillator detector and with the inclusion of the currently under study proton driver upgrade. We focus on the prospects for the experimental determination of the remaining neutrino oscillation parameters, assuming different outcomes for experiments under way or in preparation. An optimization of the beam conditions and detector location for the detection of the nu_mu to nu_e transitions is discussed. Different physics scenarios were considered, depending on the actual solution of the solar neutrino puzzle. If KamLAND measures Delta m^2_solar, we find it possible to measure both |U_{e3}|^2 and the CP violating phase delta within a viable exposure time, assuming a realistic detector and a complete data analysis. Exposure to both neutrino and antineutrino beams is necessary. We can, in addition, shed light on Delta m^2_solar if its value is at the upper limit of KamLAND sensitivity (i.e. the precise value of Delta m^2_solar remains unknown even after KamLAND). If the solar neutrino solution is not in the LMA region, we can measure |U_{e3}|^2 and determine the neutrino mass hierarchy. The existence of the proton driver is vital for the feasibility of most of these measurements.

  12. Validation of a track repeating algorithm for intensity modulated proton therapy: clinical cases study.

    PubMed

    Yepes, Pablo P; Eley, John G; Liu, Amy; Mirkovic, Dragan; Randeniya, Sharmalee; Titt, Uwe; Mohan, Radhe

    2016-04-01

    Monte Carlo (MC) methods are acknowledged as the most accurate technique to calculate dose distributions. However, due its lengthy calculation times, they are difficult to utilize in the clinic or for large retrospective studies. Track-repeating algorithms, based on MC-generated particle track data in water, accelerate dose calculations substantially, while essentially preserving the accuracy of MC. In this study, we present the validation of an efficient dose calculation algorithm for intensity modulated proton therapy, the fast dose calculator (FDC), based on a track-repeating technique. We validated the FDC algorithm for 23 patients, which included 7 brain, 6 head-and-neck, 5 lung, 1 spine, 1 pelvis and 3 prostate cases. For validation, we compared FDC-generated dose distributions with those from a full-fledged Monte Carlo based on GEANT4 (G4). We compared dose-volume-histograms, 3D-gamma-indices and analyzed a series of dosimetric indices. More than 99% of the voxels in the voxelized phantoms describing the patients have a gamma-index smaller than unity for the 2%/2 mm criteria. In addition the difference relative to the prescribed dose between the dosimetric indices calculated with FDC and G4 is less than 1%. FDC reduces the calculation times from 5 ms per proton to around 5 μs. PMID:26961764

  13. Comparative study by IBIC of Si and SiC diodes irradiated with high energy protons

    NASA Astrophysics Data System (ADS)

    Garcia Lopez, J.; Jimenez-Ramos, M. C.; Rodriguez-Ramos, M.; Ceballos, J.; Linez, F.; Raisanen, J.

    2016-04-01

    The transport properties of a series of Si and SiC diodes have been studied using the Ion Beam Induced Charge (IBIC) technique. Structural defects were induced into the samples during the irradiation with 17 MeV protons. The experimental values of the charge collection efficiency (CCE) vs bias voltages have been analyzed using a modified drift-diffusion model, which takes into account the recombination of carriers in the neutral and depletion regions. From these simulations, we have obtained the values of the carrier's lifetime for pristine and irradiated diodes, which are found to degrade faster in the case of the SiC samples. However, the decrease of the CCE at high bias voltages is more important for the Si detectors, indicative of the lower radiation hardness of this material compared to SiC. The nature of the proton-induced defects on Si wafers has been studied by Positron Annihilation Spectroscopy (PAS) and Doppler Broadening Spectroscopy (DBS). The results suggest that the main defect detected by the positrons in p-type samples is the divacancy while for n-type at least a fraction of the positron annihilate in another defect. The concentration of defects is much lower than the number of vacancies predicted by SRIM.

  14. First in situ TOF-PET study using digital photon counters for proton range verification.

    PubMed

    Cambraia Lopes, P; Bauer, J; Salomon, A; Rinaldi, I; Tabacchini, V; Tessonnier, T; Crespo, P; Parodi, K; Schaart, D R

    2016-08-21

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong (15)O signal due to its relatively short half-life (~2 min) and high oxygen content in biological tissues, enabling shorter scans that are less sensitive to biological washout. This paper presents the first performance tests of a scaled-down in situ time-of-flight (TOF) PET system based on digital photon counters (DPCs) coupled to Cerium-doped Lutetium Yttrium Silicate (LYSO:Ce) crystals, providing quantitative results representative of a dual-head tomograph that complies with spatial constraints typically encountered in clinical practice (2  ×  50°, of 360°, transaxial angular acceptance). The proton-induced activity inside polymethylmethacrylate (PMMA) and polyethylene (PE) phantoms was acquired within beam pauses (in-beam) and immediately after irradiation by an actively-delivered synchrotron pencil-beam, with clinically relevant 125.67 MeV/u, 4.6  ×  10(8) protons s(-1), and 10(10) total protons. 3D activity maps reconstructed with and without TOF information are compared to FLUKA simulations, demonstrating the benefit of TOF-PET to reduce limited-angle artefacts using a 382 ps full width at half maximum coincidence resolving time. The time-dependent contributions from different radionuclides to the total count-rate are investigated. We furthermore study the impact of the acquisition time window on the laterally integrated activity depth-profiles, with emphasis on 2 min acquisitions starting at different time points. The results depend on phantom composition and reflect the differences in relative contributions from the radionuclides originating from carbon and oxygen. We observe very good agreement between the shapes of the simulated and measured activity depth-profiles for post-beam protocols. However, our results

  15. SU-E-J-222: Feasibility Study of MRI-Only Proton Therapy Planning

    SciTech Connect

    Spadea, M; Izquierdo, D; Catana, C; Collins-Fekete, C; Bortfeld, T; Seco, J

    2015-06-15

    Purpose: To assess the dosimetric equivalence of MRI based proton planning vs. single energy x-ray CT. Methods: 8 glioblastoma patients were imaged with CT and MRI after surgical resection. T1-weighted 3DMPRAGE was used to delineate the GTV, which was subsequently rigidly registered to the CT volume. A pseudoCT was generated from the aligned MRI by combining segmentation and atlas-based approaches. The spatial resolution both for pseudo- and real CT was 0.6×0.6×2.5mm. Three orthogonal proton beams were simulated on the pseudoCT. Two co-planar beams were set on the axial plane. The third one was planned parallel to the cranio-caudal (CC) direction. Each beam was set to cover the GTV at 98% of the nominal dose (18Gy). The proton plan was copied and transferred to the real CT, including aperture/compensator geometry. Dose comparison between pseudoCT and CT plan was performed beam-by-beam by quantifying the range shift of dose profile on each slice of the GTV. The GTV’s V{sub 98} was computed for the CT. Results: For beams in axial plane the median absolute value of the range shift was 0.3mm, with 0.9mm and 1.4mm as 95th percentile and maximum, respectively. Worst scenarios were found for the CC beam, where we measured 1.1mm (median), 2.7mm (95thpercentile) and 5mm (maximum). Regardless the direction, beams passing through the surgical site, where metal (Titanium MRI-compatible) staples were present, were mostly affected by range shift. GTV’s V{sub 98} for CT was not lower than 99.3%. Conclusion: The study showed the clinical feasibility of an MRI-alone proton plan. Advantages include the possibility to rely on better soft tissue contrast for target and organs at risk delineation without the need of further CT scan and image registration. Additional investigation is required in presence of metal implants along the beam path and to account for partial volume effects due to slice thickness.

  16. First in situ TOF-PET study using digital photon counters for proton range verification

    NASA Astrophysics Data System (ADS)

    Cambraia Lopes, P.; Bauer, J.; Salomon, A.; Rinaldi, I.; Tabacchini, V.; Tessonnier, T.; Crespo, P.; Parodi, K.; Schaart, D. R.

    2016-08-01

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong 15O signal due to its relatively short half-life (~2 min) and high oxygen content in biological tissues, enabling shorter scans that are less sensitive to biological washout. This paper presents the first performance tests of a scaled-down in situ time-of-flight (TOF) PET system based on digital photon counters (DPCs) coupled to Cerium-doped Lutetium Yttrium Silicate (LYSO:Ce) crystals, providing quantitative results representative of a dual-head tomograph that complies with spatial constraints typically encountered in clinical practice (2  ×  50°, of 360°, transaxial angular acceptance). The proton-induced activity inside polymethylmethacrylate (PMMA) and polyethylene (PE) phantoms was acquired within beam pauses (in-beam) and immediately after irradiation by an actively-delivered synchrotron pencil-beam, with clinically relevant 125.67 MeV/u, 4.6  ×  108 protons s‑1, and 1010 total protons. 3D activity maps reconstructed with and without TOF information are compared to FLUKA simulations, demonstrating the benefit of TOF-PET to reduce limited-angle artefacts using a 382 ps full width at half maximum coincidence resolving time. The time-dependent contributions from different radionuclides to the total count-rate are investigated. We furthermore study the impact of the acquisition time window on the laterally integrated activity depth-profiles, with emphasis on 2 min acquisitions starting at different time points. The results depend on phantom composition and reflect the differences in relative contributions from the radionuclides originating from carbon and oxygen. We observe very good agreement between the shapes of the simulated and measured activity depth-profiles for post-beam protocols. However, our results also

  17. The role of electron microprobe mapping and dating in tectonic geochronology

    NASA Astrophysics Data System (ADS)

    Williams, M. L.; Jercinovic, M. J.; Dumond, G.; Mahan, K. H.; Flowers, R. M.

    2007-12-01

    Electron microprobe geochronology occupies a special niche within the spectrum of geochronological techniques and may be particularly relevant to the question, "What are we dating?" The technique was originally envisioned to be a low-cost, reconnaissance dating tool, opening low-resolution geochronology to a large number of researchers. However, more than a decade of research has shown that, when used in a reconnaissance fashion (i.e. using major-element analytical techniques for trace-element analysis) uncertainties are unsuitably large (several 10s of m.y. or more) for solving most tectonic problems. Using trace element analytical techniques (background modeling, interference correction, highly conductive coating, multi-analysis measurement, etc.) precision and accuracy are dramatically increased, but analysis time and cost are also increased, challenging the "quick, cheap, and easy" description. The power of microprobe geochronology comes from the spatial resolution and the natural integration with compositional data. High-resolution compositional mapping is valuable for all in-situ geochronology. Large area maps provide petrologic and textural context for chronometer phases; small scale maps illuminate the history of the chronometers themselves. Compositional maps associated with monazite are particularly informative, but examples from the East Athabasca granulite terrane using zircon, titanite, and rutile will be discussed. Most monazite crystals are 30μ or less and most have several compositional domains. Rim compositions and dates are particularly critical because they can commonly be tied to reactions and to matrix texture and fabric. Commonly, rims and internal sub domains are several microns in width and can only be analyzed by electron probe. Y has been widely used to tie monazite to Grt growth or breakdown, but current studies use a suite of trace and REE (Y, Sm, Nd, Ca, Eu, Gd, etc) to tie monazite into chemical reactions. A rapidly growing

  18. Theoretical and experimental studies of the isomeric protonation in solution for a prototype aliphatic ring containing two nitrogens

    PubMed Central

    Maheshwari, Aditya; Kim, Yong-Wah

    2009-01-01

    Theoretical calculations were carried out for studying the tautomeric protonation of N-methyl piperazine as a prototype six-member aliphatic ring containing a secondary and a tertiary nitrogen atom. The protonation was investigated in three solvents: water, acetonitrile, and dichloromethane. Calculations were performed up to the B3LYP/aug-cc-pvtz and QCISD(T)/CBS levels by applying the IEF-PCM polarizable continuum dielectric solvent model. Relative solvation free energies also were calculated upon explicit solvent models by utilizing the free-energy perturbation theory as implemented in Monte Carlo simulations. The relative free energy for the N-methyl piperazine tautomer protonated at the secondary (NMps) rather than at the tertiary (NMpt) nitrogen was calculated at a ratio of 47/53 in infinitely dilute aqueous solution. The ratio further decreases in lower polarity solvents. In contrast, NMR experiments suggest that the protonation takes place primarily at the secondary nitrogen in 0.37 molar aqueous solution with NMps/NMpt = 80/20. The NMps tautomer is exclusive in dichloromethane at the same concentration. The discrepancy between theory and experiment was resolved by considering association equilibria in parallel with the protonation for the solute. As a result, the theoretically predicted tautomer ratios were obtained in close agreement with the experimental values. The NMps tautomer could form a preferable dimeric structure, where one or two chloride anion(s) is/are in hydrogen bonds with protons of the associating monomers. The calculations suggest that the proton relocation may take place by solvent assistance in water or along an intramolecular proton jump in the twist-boat conformation. The predicted activation free energy was about 10 kcal/mol on the basis of variable temperature NMR experiments in DCM. PMID:19994881

  19. SU-D-BRE-05: Feasibility and Limitations of Laser-Driven Proton Therapy: A Treatment Planning Study

    SciTech Connect

    Hofmann, K; Wilkens, J; Masood, U; Pawelke, J

    2014-06-01

    Purpose: Laser-acceleration of particles may offer a cost- and spaceefficient alternative for future radiation therapy with particles. Laser-driven particle beams are pulsed with very short bunch times, and a high number of particles is delivered within one laser shot which cannot be portioned or modulated during irradiation. The goal of this study was to examine whether good treatment plans can be produced for laser-driven proton beams and to investigate the feasibility of a laser-driven treatment unit. Methods: An exponentially decaying proton spectrum was tracked through a gantry and energy selection beam line design to produce multiple proton spectra with different energy widths centered on various nominal energies. These spectra were fed into a treatment planning system to calculate spot scanning proton plans using different lateral widths of the beam and different numbers of protons contained in the initial spectrum. The clinical feasibility of the resulting plans was analyzed in terms of dosimetric quality and the required number of laser shots as an estimation of the overall treatment time. Results: We were able to produce treatment plans with plan qualities of clinical relevance for a maximum initial proton number per laser shot of 6*10{sup 8}. However, the associated minimum number of laser shots was in the order of 10{sup 4}, indicating a long delivery time in the order of at least 15 minutes, when assuming an optimistic repetition rate of the laser system of 10 Hz. Conclusion: With the simulated beam line and the assumed shape of the proton spectrum it was impossible to produce clinically acceptable treatment plans that can be delivered in a reasonable time. The situation can be improved by a method or a device in the beam line which can modulate the number of protons from shot to shot. Supported by DFG Cluster of Excellence: Munich-Centre for Advanced Photonics.

  20. Computational study of transport and energy deposition of intense laser-accelerated proton beams in solid density matter

    NASA Astrophysics Data System (ADS)

    Kim, J.; McGuffey, C.; Qiao, B.; Beg, F. N.; Wei, M. S.; Grabowski, P. E.

    2015-11-01

    With intense proton beams accelerated by high power short pulse lasers, solid targets are isochorically heated to become partially-ionized warm or hot dense matter. In this regime, the thermodynamic state of the matter significantly changes, varying the proton stopping power where both bound and free electrons contribute. Additionally, collective beam-matter interaction becomes important to the beam transport. We present self-consistent hybrid particle-in-cell (PIC) simulation results of proton beam transport and energy deposition in solid-density matter, where the individual proton stopping and the collective effects are taken into account simultaneously with updates of stopping power in the varying target conditions and kinetic motions of the beam in the driven fields. Broadening of propagation range and self-focusing of the beam led to unexpected target heating by the intense proton beams, with dependence on the beam profiles and target conditions. The behavior is specifically studied for the case of an experimentally measured proton beam from the 1.25 kJ, 10 ps OMEGA EP laser transporting through metal foils. This work was supported by the U.S. DOE under Contracts No. DE-NA0002034 and No. DE-AC52-07NA27344 and by the U.S. AFOSR under Contract FA9550-14-1-0346.

  1. Study Of Short-Range Correlations With 6-9 GeV/c Protons

    SciTech Connect

    Watson, J. W.

    2008-10-13

    We studied the {sup 12}C(p,2p+n) reaction at beam momenta of 5.9, 8.0 and 9.0 GeV/c. For quasielastic (p,2p) events we reconstructed p{sub f}, the momentum of the knocked-out proton before the reaction;, p{sub f} was then compared (event-by-event) with p{sub n}, the measured, coincident neutron momentum. For |p{sub n}|>k{sub F} = 0.220 GeV/c(the Fermi momentum) a strong back-to-back directional correlation between p{sub f} and p{sub n} was observed, indicative of short-range n-p correlations. From these data we concluded that for nuclear protons with momenta >0.275 GeV/c, 92{+-}18% have correlated neutron partners. This result was recently corroborated by an experiment with 4.6 GeV electrons.

  2. Wide angle Compton scattering on the proton: study of power suppressed corrections

    NASA Astrophysics Data System (ADS)

    Kivel, N.; Vanderhaeghen, M.

    2015-10-01

    We study the wide angle Compton scattering process on a proton within the soft-collinear factorization (SCET) framework. The main purpose of this work is to estimate the effect due to certain power suppressed corrections. We consider all possible kinematical power corrections and also include the subleading amplitudes describing the scattering with nucleon helicity flip. Under certain assumptions we present a leading-order factorization formula for these amplitudes which includes the hard- and soft-spectator contributions. We apply the formalism and perform a phenomenological analysis of the cross section and asymmetries in the wide angle Compton scattering on a proton. We assume that in the relevant kinematical region where -t,-u>2.5 GeV2 the dominant contribution is provided by the soft-spectator mechanism. The hard coefficient functions of the corresponding SCET operators are taken in the leading-order approximation. The analysis of existing cross section data shows that the contribution of the helicity-flip amplitudes to this observable is quite small and comparable with other expected theoretical uncertainties. We also show predictions for double polarization observables for which experimental information exists.

  3. Resonance Raman studies of bathorhodopsin: evidence for a protonated Schiff base linkage.

    PubMed

    Eyring, G; Mathies, R

    1979-01-01

    A dual beam pump/probe technique has been used with a 585-nm probe wavelength to obtain maximal resonance enhancement of the Raman lines of bathorhodopsin in a photostationary steady-state mixture at -160 degrees C. These studies show that bathorhodopsin has a protonated Schiff base vibration at 1657 cm(-1) which shifts upon deuteration to 1625 cm(-1). Within our experimental error (+/-2 cm(-1)) these frequencies are identical to those observed in rhodopsin and isorhodopsin. These effects show that the strength of the C=N bond and the degree of protonation of the Schiff base nitrogen are the same in bathorhodopsin, rhodopsin, and isorhodopsin. The implication of these results for the structure of the retinal chromophore in bathorhodopsin are discussed. The resonance Raman spectrum of pure bathorhodopsin has been generated by accurately subtracting the residual contributions of rhodopsin and isorhodopsin from spectra of the low temperature photostationary mixture. Bathorhodopsin is found to have lines at 853, 875, 920, 1006, 1166, 1210, 1278, 1323, 1536, and 1657 cm(-1). Also, by using an intensified vidicon detector, we have observed Raman scattering from bathorhodopsin at room temperature by generating a photostationary steady state with pulsed laser excitation. At room temperature the three characteristic lines of bathorhodopsin are found at 858, 873, and 920 cm(-1). The fact that the frequencies of these bathorhodopsin lines are nearly identical at both temperatures implies that the retinal conformation in bathorhodopsin formed at -160 degrees C is the same as that formed at room temperature. PMID:284349

  4. Low Temperature 1H MAS NMR Spectroscopy Studies of Proton Motion in Zeolite

    SciTech Connect

    Huo, H.; Peng, L; Grey, C

    2009-01-01

    Low temperature {sup 1}H MAS NMR spectroscopy is used to study protonic motion in zeolite HZSM-5 in both samples that have been dried using procedures that are standard in the literature and samples that have been more carefully dehydrated. A significant enhancement of proton mobility is seen for the ''standard'' dehydrated HZSM-5 sample in comparison to that seen for the much drier sample. This is ascribed to a vehicle-hopping mechanism involving the residual water that is present in these zeolites. A gradual change of the framework structure is observed on cooling to approximately 213 K, as monitored via the change in {sup 1}H chemical shift values of the Broensted acid resonances and by X-ray diffraction. A more sudden change in structure is seen by differential scanning calorimetry and NMR at approximately 220?230 K, which is associated with changes in both the mobility and the modes of binding of the residual water to the Broensted acid sites and the zeolite framework.

  5. Study of spatial resolution of proton computed tomography using a silicon strip detector

    NASA Astrophysics Data System (ADS)

    Saraya, Y.; Izumikawa, T.; Goto, J.; Kawasaki, T.; Kimura, T.

    2014-01-01

    Proton computed tomography (CT) is an imaging technique using a high-energy proton beam penetrating the human body and shows promise for improving the quality of cancer therapy with high-energy particle beams because more accurate electron density distribution measurements can be achieved with proton CT. The deterioration of the spatial resolution owing to multiple Coulomb scattering is, however, a crucial issue. The control of the radiation dose and the long exposure time are also problems to be solved. We have developed a prototype system for proton CT with a silicon strip detector and performed a beam test for imaging. The distribution of the electron density has been measured precisely. We also demonstrated an improvement in spatial resolution by reconstructing the proton trajectory. A spatial resolution of 0.45 mm is achieved for a 25-mm-thick polyethylene object. This will be a useful result for upgrading proton CT application for practical use.

  6. A molecular dynamics study of intramolecular proton transfer reaction of malonaldehyde in solutions based upon mixed quantum-classical approximation. I. Proton transfer reaction in water

    SciTech Connect

    Yamada, Atsushi; Kojima, Hidekazu; Okazaki, Susumu

    2014-08-28

    In order to investigate proton transfer reaction in solution, mixed quantum-classical molecular dynamics calculations have been carried out based on our previously proposed quantum equation of motion for the reacting system [A. Yamada and S. Okazaki, J. Chem. Phys. 128, 044507 (2008)]. Surface hopping method was applied to describe forces acting on the solvent classical degrees of freedom. In a series of our studies, quantum and solvent effects on the reaction dynamics in solutions have been analysed in detail. Here, we report our mixed quantum-classical molecular dynamics calculations for intramolecular proton transfer of malonaldehyde in water. Thermally activated proton transfer process, i.e., vibrational excitation in the reactant state followed by transition to the product state and vibrational relaxation in the product state, as well as tunneling reaction can be described by solving the equation of motion. Zero point energy is, of course, included, too. The quantum simulation in water has been compared with the fully classical one and the wave packet calculation in vacuum. The calculated quantum reaction rate in water was 0.70 ps{sup −1}, which is about 2.5 times faster than that in vacuum, 0.27 ps{sup −1}. This indicates that the solvent water accelerates the reaction. Further, the quantum calculation resulted in the reaction rate about 2 times faster than the fully classical calculation, which indicates that quantum effect enhances the reaction rate, too. Contribution from three reaction mechanisms, i.e., tunneling, thermal activation, and barrier vanishing reactions, is 33:46:21 in the mixed quantum-classical calculations. This clearly shows that the tunneling effect is important in the reaction.

  7. SU-E-T-214: Intensity Modulated Proton Therapy (IMPT) Based On Passively Scattered Protons and Multi-Leaf Collimation: Prototype TPS and Dosimetry Study

    SciTech Connect

    Sanchez-Parcerisa, D; Carabe-Fernandez, A

    2014-06-01

    Purpose. Intensity-modulated proton therapy is usually implemented with multi-field optimization of pencil-beam scanning (PBS) proton fields. However, at the view of the experience with photon-IMRT, proton facilities equipped with double-scattering (DS) delivery and multi-leaf collimation (MLC) could produce highly conformal dose distributions (and possibly eliminate the need for patient-specific compensators) with a clever use of their MLC field shaping, provided that an optimal inverse TPS is developed. Methods. A prototype TPS was developed in MATLAB. The dose calculation process was based on a fluence-dose algorithm on an adaptive divergent grid. A database of dose kernels was precalculated in order to allow for fast variations of the field range and modulation during optimization. The inverse planning process was based on the adaptive simulated annealing approach, with direct aperture optimization of the MLC leaves. A dosimetry study was performed on a phantom formed by three concentrical semicylinders separated by 5 mm, of which the inner-most and outer-most were regarded as organs at risk (OARs), and the middle one as the PTV. We chose a concave target (which is not treatable with conventional DS fields) to show the potential of our technique. The optimizer was configured to minimize the mean dose to the OARs while keeping a good coverage of the target. Results. The plan produced by the prototype TPS achieved a conformity index of 1.34, with the mean doses to the OARs below 78% of the prescribed dose. This Result is hardly achievable with traditional conformal DS technique with compensators, and it compares to what can be obtained with PBS. Conclusion. It is certainly feasible to produce IMPT fields with MLC passive scattering fields. With a fully developed treatment planning system, the produced plans can be superior to traditional DS plans in terms of plan conformity and dose to organs at risk.

  8. Nuclear Structure of 8B Studied by Proton Resonance Scatterings on 7Be

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Wakabayashi, Y.; Hayakawa, S.; Amadio, G.; Kubono, S.; Fujikawa, H.; Saito, A.; He, J. J.; Teranishi, T.; Kwon, Y. K.; Nishimura, S.; Togano, Y.; Iwasa, N.; Inafuku, K.; Niikura, M.; Binh, D. N.; Khiem, L. H.

    2008-05-01

    A new measurement of the proton resonance scattering on 7Be was performed up to the excitation energy of 6.8 MeV using the low-energy RI beam facility CRIB (CNS Radioactive Ion Beam separator) at the Center for Nuclear Study (CNS) of the University of Tokyo. The excitation function of 8B above 3.5 MeV was successfully measured for the first time, providing important information about the reaction rate of 7Be(p,γ)8B, which is the key reaction in the solar 8B neutrino production. For more intensive experimental studies with RI beams, the development of a cryogenic gas target system is ongoing at CNS. In this paper a preliminary result of the 7Be experiment and the present status of the development of the target system are presented.

  9. Study on the damage effects of electron and proton combined irradiation on T700/cyanate composites

    NASA Astrophysics Data System (ADS)

    Qin, Wei; Peng, Dequn; Wu, Xiaohong

    2013-10-01

    The synergistic effects of electron and proton co-irradiation with an energy of 160 keV in ultrahigh vacuum environment on T700/cyanate composites was studied through examining the alteration of their interlayer shear strength (ILSS) and mass loss. The surface molecular structure and chemical composition of T700/cyanate composites before and after co-irradiation were studied by IR and XPS, respectively. The results indicate that under low co-irradiation fluence of less than 1.0 × 1016 e(p)/cm2, the cross-linking density of cyanate in the surface layer increased with fluence, resulting in increased ILSS of the composite. However a further increase in fluence caused the ILSS to decrease. Besides surface cross-linking, co-irradiation in high vacuum broke the surface chemical bonds. As a result, the mass loss and formation of a carbon-rich layer at thesurface of T700/cyanate composites took place.

  10. Nuclear Structure of {sup 8}B Studied by Proton Resonance Scatterings on {sup 7}Be

    SciTech Connect

    Yamaguchi, H.; Wakabayashi, Y.; Hayakawa, S.; Amadio, G.; Kubono, S.; Fujikawa, H.; Niikura, M.; Binh, D. N.; Saito, A.; He, J. J.; Teranishi, T.; Kwon, Y. K.; Nishimura, S.; Togano, Y.; Iwasa, N.; Inafuku, K.; Khiem, L. H.

    2008-05-21

    A new measurement of the proton resonance scattering on {sup 7}Be was performed up to the excitation energy of 6.8 MeV using the low-energy RI beam facility CRIB (CNS Radioactive Ion Beam separator) at the Center for Nuclear Study (CNS) of the University of Tokyo. The excitation function of {sup 8}B above 3.5 MeV was successfully measured for the first time, providing important information about the reaction rate of {sup 7}Be(p,{gamma}){sup 8}B, which is the key reaction in the solar {sup 8}B neutrino production. For more intensive experimental studies with RI beams, the development of a cryogenic gas target system is ongoing at CNS. In this paper a preliminary result of the {sup 7}Be experiment and the present status of the development of the target system are presented.

  11. Sensitivity study of proton radiography and comparison with kV and MV x-ray imaging using GEANT4 Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Depauw, Nicolas; Seco, Joao

    2011-04-01

    The imaging sensitivity of proton radiography has been studied and compared with kV and MV x-ray imaging using Monte Carlo simulations. A phantom was specifically modeled using 21 different material inserts with densities ranging from 0.001 to 1.92 g cm-3. These simulations were run using the MGH double scattered proton beam, scanned pencil proton beams from 200 to 490 MeV, as well as pure 50 keV, 100 keV, 1 MeV and 2 MeV gamma x-ray beams. In order to compare the physics implied in both proton and photon radiography without being biased by the current state of the art in detector technology, the detectors were considered perfect. Along with spatial resolution, the contrast-to-noise ratio was evaluated and compared for each material. These analyses were performed using radiographic images that took into account the following: only primary protons, both primary and secondary protons, and both contributions while performing angular and energetic cuts. Additionally, tissue-to-tissue contrasts in an actual lung cancer patient case were studied for simulated proton radiographs and compared against the original kV x-ray image which corresponds to the current patient set-up image in the proton clinic. This study highlights the poorer spatial resolution of protons versus x-rays for radiographic imaging purposes, and the excellent density resolution of proton radiography. Contrasts around the tumor are higher using protons in a lung cancer patient case. The high-density resolution of proton radiography is of great importance for specific tumor diagnostics, such as in lung cancer, where x-ray radiography operates poorly. Furthermore, the use of daily proton radiography prior to proton therapy would ameliorate patient set-up while reducing the absorbed dose delivered through imaging.

  12. Study of interaction of proton transfer probe 1-hydroxy-2-naphthaldehyde with serum albumins: a spectroscopic study.

    PubMed

    Balia Singh, Rupashree; Mahanta, Subrata; Guchhait, Nikhil

    2008-04-25

    In the present work, we have studied the interaction of proton transfer probe 1-hydroxy-2-naphthaldehyde (HN12) with Human Serum Albumin (HSA) and Bovine Serum Albumin (BSA) by steady state absorption and emission spectroscopy combined with time resolved fluorescence measurements. The measured binding constant (K) and free energy change (DeltaG) indicate a stronger affinity of HN12 molecule for HSA than BSA. Steady state anisotropy, excitation anisotropy and fluorescence resonance energy transfer (FRET) studies indicate that the probe molecule resides at the hydrophobic site of the protein environment. PMID:18296059

  13. Theoretical study on the effect of solvent and intermolecular fluctuations in proton transfer reactions: General theory

    SciTech Connect

    Kato, Nobuhiko; Ida, Tomonori; Endo, Kazunaka

    2004-04-30

    We present a theory of proton transfer reactions which incorporate the modulation of the proton's potential surface by intermolecular vibrations and the effect of coupling to solvent degree of freedom. The proton tunnels between states corresponding to it being localized in the wells of a double minimum potential. The resulting tunnel splitting depends on the intermolecular separation. The solvent response to the proton's charge is modeled as that of a continuous distribution of harmonic oscillators and the intermolecular stretching mode is also damped because of the interaction with solvent degree of freedom. The transition rate is given by the Fermi Gorlden Rule expression.

  14. Super-achromatic microprobe for ultrahigh-resolution endoscopic OCT imaging at 800 nm (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yuan, Wu; Alemohammad, Milad; Yu, Xiaoyun; Yu, Shaoyong; Li, Xingde

    2016-03-01

    In this paper, we report a super-achromatic microprobe made with fiber-optic ball lens to enable ultrahigh-resolution endoscopic OCT imaging. An axial resolution of ~2.4 µm (in air) can be achieved with a 7-fs Ti:Sapphire laser. The microprobe has minimal astigmatism which affords a high transverse resolution of ~5.6 µm. The miniaturized microprobe has an outer diameter of ~520 µm including the encasing metal guard and can be used to image small luminal organs. The performance of the ultrahigh-resolution OCT microprobe was demonstrated by imaging rat esophagus, guinea pig esophagus, and mouse rectum in vivo.

  15. Electrostatic microprobe for determining charge domains on surfaces.

    PubMed

    Fletcher, Robert A

    2015-11-01

    An electrostatic microprobe was developed to measure charge on wipes and various test surfaces. The device is constructed on an optical microscope platform utilizing a computer controlled XY stage. Test surfaces can be optically imaged to identify microscopic features that can be correlated to the measured charge domain maps. The ultimate goal is to quantify charge on wipe cloths to determine the influence of electrostatic forces on wipe sampling efficiency. We found that certain wipe materials do not extensively charge while others accumulate charge by making contact with other surfaces (through the triboelectric effect). Charge domains are found to be nonuniform. PMID:26628139

  16. Electrostatic microprobe for determining charge domains on surfaces

    NASA Astrophysics Data System (ADS)

    Fletcher, Robert A.

    2015-11-01

    An electrostatic microprobe was developed to measure charge on wipes and various test surfaces. The device is constructed on an optical microscope platform utilizing a computer controlled XY stage. Test surfaces can be optically imaged to identify microscopic features that can be correlated to the measured charge domain maps. The ultimate goal is to quantify charge on wipe cloths to determine the influence of electrostatic forces on wipe sampling efficiency. We found that certain wipe materials do not extensively charge while others accumulate charge by making contact with other surfaces (through the triboelectric effect). Charge domains are found to be nonuniform.

  17. Rapid correction of electron microprobe data for multicomponent metallic systems

    NASA Technical Reports Server (NTRS)

    Gupta, K. P.; Sivakumar, R.

    1973-01-01

    This paper describes an empirical relation for the correction of electron microprobe data for multicomponent metallic systems. It evaluates the empirical correction parameter, a for each element in a binary alloy system using a modification of Colby's MAGIC III computer program and outlines a simple and quick way of correcting the probe data. This technique has been tested on a number of multicomponent metallic systems and the agreement with the results using theoretical expressions is found to be excellent. Limitations and suitability of this relation are discussed and a model calculation is also presented in the Appendix.

  18. A comprehensive spectrometry study of a stray neutron radiation field in scanning proton therapy

    NASA Astrophysics Data System (ADS)

    Mares, Vladimir; Romero-Expósito, Maite; Farah, Jad; Trinkl, Sebastian; Domingo, Carles; Dommert, Martin; Stolarczyk, Liliana; Van Ryckeghem, Laurent; Wielunski, Marek; Olko, Pawel; Harrison, Roger M.

    2016-06-01

    The purpose of this study is to characterize the stray neutron radiation field in scanning proton therapy considering a pediatric anthropomorphic phantom and a clinically-relevant beam condition. Using two extended-range Bonner sphere spectrometry systems (ERBSS), Working Group 9 of the European Radiation Dosimetry Group measured neutron spectra at ten different positions around a pediatric anthropomorphic phantom irradiated for a brain tumor with a scanning proton beam. This study compares the different systems and unfolding codes as well as neutron spectra measured in similar conditions around a water tank phantom. The ten spectra measured with two ERBSS systems show a generally similar thermal component regardless of the position around the phantom while high energy neutrons (above 20 MeV) were only registered at positions near the beam axis (at 0°, 329° and 355°). Neutron spectra, fluence and ambient dose equivalent, H *(10), values of both systems were in good agreement (<15%) while the unfolding code proved to have a limited effect. The highest H *(10) value of 2.7 μSv Gy‑1 was measured at 329° to the beam axis and 1.63 m from the isocenter where high-energy neutrons (E  ⩾  20 MeV) contribute with about 53%. The neutron mapping within the gantry room showed that H *(10) values significantly decreased with distance and angular position with respect to the beam axis dropping to 0.52 μSv Gy‑1 at 90° and 3.35 m. Spectra at angles of 45° and 135° with respect to the beam axis measured here with an anthropomorphic phantom showed a similar peak structure at the thermal, fast and high energy range as in the previous water-tank experiments. Meanwhile, at 90°, small differences at the high-energy range were observed. Using ERBSS systems, neutron spectra mapping was performed to characterize the exposure of scanning proton therapy patients. The ten measured spectra provide precise information about the exposure of healthy organs to thermal

  19. A comprehensive spectrometry study of a stray neutron radiation field in scanning proton therapy.

    PubMed

    Mares, Vladimir; Romero-Expósito, Maite; Farah, Jad; Trinkl, Sebastian; Domingo, Carles; Dommert, Martin; Stolarczyk, Liliana; Van Ryckeghem, Laurent; Wielunski, Marek; Olko, Pawel; Harrison, Roger M

    2016-06-01

    The purpose of this study is to characterize the stray neutron radiation field in scanning proton therapy considering a pediatric anthropomorphic phantom and a clinically-relevant beam condition. Using two extended-range Bonner sphere spectrometry systems (ERBSS), Working Group 9 of the European Radiation Dosimetry Group measured neutron spectra at ten different positions around a pediatric anthropomorphic phantom irradiated for a brain tumor with a scanning proton beam. This study compares the different systems and unfolding codes as well as neutron spectra measured in similar conditions around a water tank phantom. The ten spectra measured with two ERBSS systems show a generally similar thermal component regardless of the position around the phantom while high energy neutrons (above 20 MeV) were only registered at positions near the beam axis (at 0°, 329° and 355°). Neutron spectra, fluence and ambient dose equivalent, H (*)(10), values of both systems were in good agreement (<15%) while the unfolding code proved to have a limited effect. The highest H (*)(10) value of 2.7 μSv Gy(-1) was measured at 329° to the beam axis and 1.63 m from the isocenter where high-energy neutrons (E  ⩾  20 MeV) contribute with about 53%. The neutron mapping within the gantry room showed that H (*)(10) values significantly decreased with distance and angular position with respect to the beam axis dropping to 0.52 μSv Gy(-1) at 90° and 3.35 m. Spectra at angles of 45° and 135° with respect to the beam axis measured here with an anthropomorphic phantom showed a similar peak structure at the thermal, fast and high energy range as in the previous water-tank experiments. Meanwhile, at 90°, small differences at the high-energy range were observed. Using ERBSS systems, neutron spectra mapping was performed to characterize the exposure of scanning proton therapy patients. The ten measured spectra provide precise information about the exposure of healthy organs to

  20. Implantable Microprobe with Arrayed Microsensors for Combined Amperometric Monitoring of the Neurotransmitters, Glutamate and Dopamine.

    PubMed

    Tseng, Tina T-C; Monbouquette, Harold G

    2012-08-15

    An implantable, micromachined microprobe with a microsensor array for combined monitoring of the neurotransmitters, glutamate (Glut) and dopamine (DA), by constant potential amperometry has been created and characterized. Microprobe studies in vitro revealed Glut and DA microsensor sensitivities of 126±5 nA·μM(-1)·cm(-2) and 3250±50 nA·μM(-1)·cm(-2), respectively, with corresponding detection limits of 2.1±0.2 μM and 62±8 nM, both at comparable ~1 sec response times. No diffusional interaction of H(2)O(2) among arrayed microelectrodes was observed. Also, no responses from the electroactive interferents, ascorbic acid (AA), uric acid (UA), DOPA (a DA catabolite) or DOPAC (a DA precursor), over their respective physiological concentration ranges, were detected. The dual sensing microbe attributes of size, detection limit, sensitivity, response time and selectivity make it attractive for combined sensing of Glut and DA in vivo. PMID:23139647

  1. Development of Ultra Low Temperature, Impact Resistant Lithium Battery for the Mars Microprobe

    NASA Technical Reports Server (NTRS)

    Frank, H.; Deligiannis, F.; Davies, E.; Ratnakumar, Bugga V.; Surampudi, S.; Russel, P. G.; Reddy, T. B.

    1998-01-01

    The requirements of the power source for the Mars Microprobe, to be backpacked on the Mars 98 Spacecraft, are fairly demanding, with survivability to a shock of the order of 80,000 g combined with an operational requirement at -80 C. Development of a suitable power system, based on primary lithium-thionyl chloride is underway for the last eighteen months, together with Yardney Technical Products Inc., Pawcatuck, CT. The battery consists of 4 cells of 2 Ah capacity at 25 C, of which at least 25 % would be available at -80 C, at a moderate rate of C/20. Each probe contains two batteries and two such probes will be deployed. The selected cell is designed around an approximate 1/2 "D" cells, with flat plate electrodes. Significant improvements to the conventional Li-SOCl2 cell include: (a) use of tetrachlorogallate salt instead of aluminate for improved low temperature performance and reduced voltage delay, (b) optimization of the salt concentration, and (c) modification of the cell design to develop shock resistance to 80,000 g. We report here results from our several electrical performance tests, mission simulation tests, microcalorimetry and AC impedance studies, and Air gun tests. The cells have successfully gone through mission-enabling survivability and performance tests for the Mars Microprobe penetrator.

  2. Quantum Mechanics Studies of Fuel Cell Catalysts and Proton Conducting Ceramics with Validation by Experiment

    NASA Astrophysics Data System (ADS)

    Tsai, Ho-Cheng

    We carried out quantum mechanics (QM) studies aimed at improving the performance of hydrogen fuel cells. In part I, The challenge was to find a replacement for the Pt cathode that would lead to improved performance for the Oxygen Reduction Reaction (ORR) while remaining stable under operational conditions and decreasing cost. Our design strategy was to find an alloy with composition Pt3M that would lead to surface segregation such that the top layer would be pure Pt, with the second and subsequent layers richer in M. Under operating conditions we expect the surface to have significant O and/or OH chemisorbed on the surface; we searched for M that would remain segregated under these conditions. Using QM we examined surface segregation for 28 Pt3M alloys, where M is a transition metal. We found that only Pt3Os and Pt3Ir showed significant surface segregation when O and OH are chemisorbed on the catalyst surfaces. This result indicates that Pt3Os and Pt 3Ir favor formation of a Pt-skin surface layer structure that would resist the acidic electrolyte corrosion during fuel cell operation environments. We chose to focus on Os because the phase diagram for Pt-Ir indicated that Pt-Ir could not form a homogeneous alloy at lower temperature. To determine the performance for ORR, we used QM to examine intermediates, reaction pathways, and reaction barriers involved in the processes for which protons from the anode reactions react with O2 to form H2O. These QM calculations used our Poisson-Boltzmann implicit solvation model include the effects of the solvent (water with dielectric constant 78 with pH 7 at 298K). We also carried out similar QM studies followed by experimental validation for the Os/Pt core-shell catalyst fabricated by the underpotential deposition (UPD) method. The QM results indicated that the RDS for ORR is a compromise between the OOH formation step (0.37 eV for Pt, 0.23 eV for Pt2ML/Os core-shell) and H2O formation steps (0.32 eV for Pt, 0.22 eV for Pt2ML

  3. Study of direct single photons and correlated particles in proton-proton collisions at. sqrt. s = 62. 4 GeV

    SciTech Connect

    Angelis, A. L.S.; Besch, H. J.; Blumenfeld, B. J.

    1980-01-01

    As part of a study of large p/sub T/ phenomena in proton-proton collisions at the CERN ISR, a search for direct single photon production has been performed. A statistical division of the data sample into the fraction consistent with single photon production and the fraction due to multiphoton decays of neutral hadrons is accomplished by measuring the average conversion probability for the sample in a one radiation length thick converter. The fraction of the sample attributable to direct single photon production is < ..gamma../all > = 0.074 +- 0.012 for 6 GeV/c < p/sub T/ < 10 GeV/C, and < ..gamma../all > = 0.26 +- 0.04 for p/sub T/ > 10 GeV/c, with an additional systematic uncertainty of +- 0.05 for both values. It is found that single photons are produced preferentially with no accompanying particles on the same side. The ratio of positive to negative particles on the away side is found to be 3.7 +- 1.2 at high x/sub E/ and p/sub T/ for the single photon events.

  4. Development of an external beam nuclear microprobe on the Aglae facility of the Louvre museum

    NASA Astrophysics Data System (ADS)

    Calligaro, T.; Dran, J.-C.; Ioannidou, E.; Moignard, B.; Pichon, L.; Salomon, J.

    2000-03-01

    The external beam line of our facility has been recently equipped with the focusing system previously mounted on a classical nuclear microprobe. When using a 0.1 μm thick Si 3N 4 foil for the exit window and flowing helium on the sample under analysis, a beam spot as small as 10 μm is attainable at a distance of 3 mm from the window. Elemental micromapping is performed by mechanical scanning. An electronic device has been designed which allows XY scanning by moving the sample under the beam by steps down to 0.1 μm. Beam monitoring is carried out by means of the weak X-ray signal emitted by the exit foil and detected by a specially designed Si(Li) detector cooled by Peltier effect. The characteristics of external beams of protons and alpha particles are evaluated by means of resonance scanning and elemental mapping of a grid. An example of application is presented, dealing with elemental micro-mapping of inclusions in gemstones.

  5. Nuclear microprobe investigation of the penetration of ultrafine zinc oxide into intact and tape-stripped human skin

    NASA Astrophysics Data System (ADS)

    Szikszai, Z.; Kertész, Zs.; Bodnár, E.; Major, I.; Borbíró, I.; Kiss, Á. Z.; Hunyadi, J.

    2010-06-01

    Ultrafine metal oxides, such as titanium dioxide and zinc oxide are widely used in cosmetic and health products like sunscreens. These oxides are potent UV filters and the small particle size makes the product more transparent compared to formulations containing coarser particles. In the present work the penetration of ultrafine zinc oxide into intact and tape-stripped human skin was investigated using nuclear microprobe techniques, such as proton induced X-ray spectroscopy and scanning transmission ion microscopy. Our results indicate that the penetration of ultrafine zinc oxide, in a hydrophobic basis gel with 48 h application time, is limited to the stratum corneum layer of the intact skin. Removing the stratum corneum partially or entirely by tape-stripping did not cause the penetration of the particles into the deeper dermal layers; the zinc particles remained on the surface of the skin.

  6. A TCT and annealing study on Magnetic Czochralski silicon detectors irradiated with neutrons and 24 GeV/ c protons

    NASA Astrophysics Data System (ADS)

    Pacifico, Nicola; Creanza, Donato; de Palma, Mauro; Manna, Norman; Kramberger, Gregor; Moll, Michael

    2010-01-01

    Silicon diodes (pad detectors) were irradiated with 24 GeV/ c protons at the CERN PS IRRAD1 facility and with neutrons at the TRIGA reactor in Ljubljana (Slovenia). The diodes were realized on Magnetic Czochralski (MCz) grown silicon, of both n- and p-type. After irradiation, an annealing study with CV measurements was performed on 24 GeV/ c proton irradiated detectors, looking for hints of type inversion after irradiation and during annealing. Other pad detectors were studied using the TCT (transient current technique), to gather information about the field profile in the detector bulk and thus about the effective space charge distribution within it.

  7. Long term study of solar wind proton dynamics near 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Behar, Etienne; Nilsson, Hans; Steinberg Wieser, Gabriella

    2016-04-01

    The Rosetta mission has been escorting comet 67P/Churyumov-Gerasimenko since early August 2014, spanning heliocentric distances from 3.65AU to 1.24AU (the comet perihelion, reached on August 2015). Data presented here were collected during this phase: as the heliocentric distance decreases with time, the nucleus activity increases, and the interaction between the solar wind and the atmosphere of 67P evolves and becomes more complex. At low activity, the partially ionized coma is permeated by the solar wind. It adds mass to this plasma flow, which in turn is slowed down and deflected. As coma densities get gradually higher, this mass loading phenomenon intensifies, to the point where the solar wind is not observed anymore in the inner region of the coma. We present a long term study of the solar wind protons, focusing on their deflection and plasma parameters.

  8. First proton-transfer study of 18F + p resonances relevant for novae

    SciTech Connect

    Adekola, A. S.; Bardayan, Daniel W; Blackmon, Jeff C; Brune, C.; Chae, K. Y.; Domizioli, C.; Greife, U.; Heinen, Z.; Hornish, M.; Jones, K. L.; Kozub, R. L.; Livesay, R. J.; Ma, Z.; Massey, T.; Moazen, Brian; Nesaraja, Caroline D; Pain, S. D.; ShrinerJr., J. F.; Smith, N. D.; Smith, Michael Scott; Thomas, J. S.; Visser, D. W.; Voinov, A.

    2011-01-01

    The 18F(p, )15O reaction is the predominant destruction mechanism in novae of the radionuclide 18F, a target of -ray observatories. Thus, its rate is important for understanding 18F production in novae. We have studied resonances in the 18F+p system by making a measurement of a protontransfer reaction 18F(d,n). We have observed 15 19Ne levels, 5 of which are below the proton threshold, including a subthreshold state, which has significant lp=0 strength. Our data provide a direct determination of the spectroscopic strength of these states and new constraints on their spins and parities, thereby resolving a controversy, which involves the 8- and 38- keV resonances. The 18F(p, )15O reaction rate is reevaluated, which takes the subthreshold resonance and other new information determined in this experiment into account.

  9. RBE-LET relationship for proton and alpha irradiations studied with a nanodosimetric approach.

    PubMed

    Villagrasa, C; Dos Santos, M; Bianco, D; Gruel, G; Barquinero, J F; Clairand, I

    2014-10-01

    Relative Biological Effectiveness (RBE) values are used to characterise the biological efficiency of different radiation qualities relative to photon irradiations. The RBE-high linear energy transfer (LET) relation for ion irradiations presents general features that the authors propose to look at using a nanometric description of the energy deposition of these ion irradiations (protons and alphas of different energies). In this work, the simulation of the energy transfer points in the tracks was made by Monte Carlo method using the Geant4-DNA processes and a nanometric description of the target of interest for studying biological effects, the DNA molecule. Results were obtained concerning the sensitive volume to be considered for direct DNA clustered damages that could be related to late biological effects. PMID:24759916

  10. Studies and calculations of transverse emittance growth in high-energy proton storage rings

    SciTech Connect

    Mane, S.R.; Jackson, G.

    1989-03-01

    In the operation of proton-antiproton colliders, an important goal is to maximize the integrated luminosity. During such operations in the Fermilab Tevatron, the transverse beam emittances were observed to grow unexpectedly quickly, thus causing a serious reduction of the luminosity. We have studied this phenomenon experimentally and theoretically. A formula for the emittance growth rate, due to random dipole kicks, is derived. In the experiment, RF phase noise of known amplitude was deliberately injected into the Tevatron to kick the beam randomly, via dispersion at the RF cavities. Theory and experiment are found to agree reasonably well. We also briefly discuss the problem of quadrupole kicks. 14 refs., 2 figs., 3 tabs.

  11. In vitro proton NMR study of collagen in human aortic wall.

    PubMed

    Vinée, P; Meurer, B; Constantinesco, A; Kohlberger, B; Hauenstein, K H; Laubenberger, J

    1993-03-01

    The authors relate the findings in the 1H solid state line shape (at 60 MHz) of human aortic walls (n = 12) in native state and after histologically controlled selective lysis of collagen and elastin. An analysis of the line shape shows a composite free induction decay (FID) consisting of a low amplitude (3-7%) fast decaying component (T2 approximately 20 microseconds) and a slow decaying one (T2 > 1 ms). The fast component is identified as the protons of the collagen macromolecules. The second moment computed from the experimental fast component of the FID is in agreement with published studies examining the motional characteristics of collagen by multinuclear NMR employing spin labeling. A theoretical second moment is computed for the collagen macromolecular backbone from the atomic positions in the superhelix. Comparison with the observed experimental values allows determination of the step angle (29 degrees) of the fast rotational motion of the collagen strands along their long axis. PMID:8383787

  12. Protonation effects on the UV/Vis absorption spectra of imatinib: A theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Grante, Ilze; Actins, Andris; Orola, Liana

    2014-08-01

    An experimental and theoretical investigation of protonation effects on the UV/Vis absorption spectra of imatinib showed systematic changes of absorption depending on the pH, and a new absorption band appeared below pH 2. These changes in the UV/Vis absorption spectra were interpreted using quantum chemical calculations. The geometry of various imatinib cations in the gas phase and in ethanol solution was optimized with the DFT/B3LYP method. The resultant geometries were compared to the experimentally determined crystal structures of imatinib salts. The semi-empirical ZINDO-CI method was employed to calculate the absorption lines and electronic transitions. Our study suggests that the formation of the extra near-UV absorption band resulted from an increase of imatinib trication concentration in the solution, while the rapid increase of the first absorption maximum could be attributed to both the formation of imatinib trication and tetracation.

  13. Study on the mechanical properties evolution of A508-3 steel under proton irradiation

    NASA Astrophysics Data System (ADS)

    Lei, Jing; Ding, Hui; Shu, Guo-gang; Wan, Qiang-mao

    2014-11-01

    In an effort to study the effect of irradiation on the hardening behavior of reactor pressure vessel (RPV) steel, nanoindentation was employed to investigate the mechanical properties of A508-3 steel after an irradiation with 190 keV proton to the dose range of 0.054-0.271 displacement per atom (dpa) at room temperature. The results show that the relationship between the nanohardness and indent depth is in accordance with the Nix-Gao model. The nanohardness of A508-3 steel increases notably with the dose. In addition, the contribution of the irradiation-induced microstructural defects including matrix damage and nano clusters to the irradiation hardening is discussed.

  14. First principles studies of proton conduction in KTaO3.

    PubMed

    Kang, Sung Gu; Sholl, David S

    2014-07-14

    KTaO3 (KTO) is a useful prototypical perovskite for examining the mechanisms of proton transport in perovskites. Previously, Gomez et al. [J. Chem. Phys. 126, 194701 (2007)] reported density functional theory (DFT) calculations describing proton hopping in defect-free KTO. We use DFT calculations to extend that work in two directions, namely, understanding isotope effects in low and high temperature proton transport and the role of native point defects in KTO. At cryogenic temperatures, quantum tunneling plays a vital role in the net hopping of protons in KTO. At the elevated temperature characteristic of applications involving proton-conducting perovskites, tunneling is negligible but zero point energy effects still lead to non-negligible isotope effects for H(+), D(+), and T(+). We also use DFT to characterize the populations of relevant point defects in KTO as a function of experimental conditions, and to examine the migration of protons that are close in proximity to these defects. This information gives useful insight into the overall transport rates of protons through KTO under a variety of external environments. We also assess the overall diffusivity of protons in KTO at various ranges of oxygen vacancy concentrations by performing kinetic Monte Carlo simulations. PMID:25028038

  15. First principles studies of proton conduction in KTaO3

    NASA Astrophysics Data System (ADS)

    Kang, Sung Gu; Sholl, David S.

    2014-07-01

    KTaO3 (KTO) is a useful prototypical perovskite for examining the mechanisms of proton transport in perovskites. Previously, Gomez et al. [J. Chem. Phys. 126, 194701 (2007)] reported density functional theory (DFT) calculations describing proton hopping in defect-free KTO. We use DFT calculations to extend that work in two directions, namely, understanding isotope effects in low and high temperature proton transport and the role of native point defects in KTO. At cryogenic temperatures, quantum tunneling plays a vital role in the net hopping of protons in KTO. At the elevated temperature characteristic of applications involving proton-conducting perovskites, tunneling is negligible but zero point energy effects still lead to non-negligible isotope effects for H+, D+, and T+. We also use DFT to characterize the populations of relevant point defects in KTO as a function of experimental conditions, and to examine the migration of protons that are close in proximity to these defects. This information gives useful insight into the overall transport rates of protons through KTO under a variety of external environments. We also assess the overall diffusivity of protons in KTO at various ranges of oxygen vacancy concentrations by performing kinetic Monte Carlo simulations.

  16. First principles studies of proton conduction in KTaO{sub 3}

    SciTech Connect

    Kang, Sung Gu; Sholl, David S.

    2014-07-14

    KTaO{sub 3} (KTO) is a useful prototypical perovskite for examining the mechanisms of proton transport in perovskites. Previously, Gomez et al. [J. Chem. Phys. 126, 194701 (2007)] reported density functional theory (DFT) calculations describing proton hopping in defect-free KTO. We use DFT calculations to extend that work in two directions, namely, understanding isotope effects in low and high temperature proton transport and the role of native point defects in KTO. At cryogenic temperatures, quantum tunneling plays a vital role in the net hopping of protons in KTO. At the elevated temperature characteristic of applications involving proton-conducting perovskites, tunneling is negligible but zero point energy effects still lead to non-negligible isotope effects for H{sup +}, D{sup +}, and T{sup +}. We also use DFT to characterize the populations of relevant point defects in KTO as a function of experimental conditions, and to examine the migration of protons that are close in proximity to these defects. This information gives useful insight into the overall transport rates of protons through KTO under a variety of external environments. We also assess the overall diffusivity of protons in KTO at various ranges of oxygen vacancy concentrations by performing kinetic Monte Carlo simulations.

  17. A study of spacecraft charging due to exposure to interplanetary protons

    NASA Technical Reports Server (NTRS)

    Green, Nelson W.; Frederickson, A. Robb

    2006-01-01

    The majority of research regarding IESD has been concerned with the electrons in the space environment around the Earth and at Jupiter; little research has been done on the charging of spacecraft in interplanetary space due to solar event protons. This paper provides a review of the literature regarding IESD due to protons and presents the results of recent laboratory experiments.

  18. Application of proton boron fusion reaction to radiation therapy: A Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Yoon, Do-Kun; Jung, Joo-Young; Suh, Tae Suk

    2014-12-01

    Three alpha particles are emitted from the point of reaction between a proton and boron. The alpha particles are effective in inducing the death of a tumor cell. After boron is accumulated in the tumor region, the emitted from outside the body proton can react with the boron in the tumor region. An increase of the proton's maximum dose level is caused by the boron and only the tumor cell is damaged more critically. In addition, a prompt gamma ray is emitted from the proton boron reaction point. Here, we show that the effectiveness of the proton boron fusion therapy was verified using Monte Carlo simulations. We found that a dramatic increase by more than half of the proton's maximum dose level was induced by the boron in the tumor region. This increase occurred only when the proton's maximum dose point was located within the boron uptake region. In addition, the 719 keV prompt gamma ray peak produced by the proton boron fusion reaction was positively detected. This therapy method features the advantages such as the application of Bragg-peak to the therapy, the accurate targeting of tumor, improved therapy effects, and the monitoring of the therapy region during treatment.

  19. Application of proton boron fusion reaction to radiation therapy: A Monte Carlo simulation study

    SciTech Connect

    Yoon, Do-Kun; Jung, Joo-Young; Suh, Tae Suk

    2014-12-01

    Three alpha particles are emitted from the point of reaction between a proton and boron. The alpha particles are effective in inducing the death of a tumor cell. After boron is accumulated in the tumor region, the emitted from outside the body proton can react with the boron in the tumor region. An increase of the proton's maximum dose level is caused by the boron and only the tumor cell is damaged more critically. In addition, a prompt gamma ray is emitted from the proton boron reaction point. Here, we show that the effectiveness of the proton boron fusion therapy was verified using Monte Carlo simulations. We found that a dramatic increase by more than half of the proton's maximum dose level was induced by the boron in the tumor region. This increase occurred only when the proton's maximum dose point was located within the boron uptake region. In addition, the 719 keV prompt gamma ray peak produced by the proton boron fusion reaction was positively detected. This therapy method features the advantages such as the application of Bragg-peak to the therapy, the accurate targeting of tumor, improved therapy effects, and the monitoring of the therapy region during treatment.

  20. Design study for a superconducting proton linac from 20 to 100 MeV

    SciTech Connect

    Wangler, T.P.; Garnett, R.; Krawczyk, F.; Billen, J.; Bultman, N.; Christensen, K.; Fox, W.; Wood, R.

    1993-07-01

    Advances in superconducting radiofrequency technology during the past 15 years have made possible the large-scale application of superconducting niobium accelerators. So far this development has been restricted to rather low-current electron and heavy-ion accelerators. In addition to the power savings, the improved capability of superconducting cavities to provide acceleration of high currents with low beam losses, which follows from the ability to use larger beam apertures without a large economic penalty from increased rf losses, could make superconducting proton linacs very attractive for high-intensity applications, where activation of the accelerator is a major concern. During the past year, at Los Alamos, the authors have been looking at a possible upgrade to the 800-MeV LAMPF proton accelerator, to provide higher intensity injection into a new storage ring for a new high-intensity pulsed neutron source. As part of this upgrade to the LAMPF accelerator, the entire linac below 100 MeV would be rebuilt to provide improved beam quality, improved reliability, and to include funneling at 20 MeV for higher beam currents. Both a room-temperature and a superconducting option are being considered for the section from 20 to 100 MeV. At present, this section is a 201.25 MHz room-temperature copper drift-tube linac (DTL). For this new upgrade scenario the frequency from 20 to 100 MeV was fixed at 805 MHz. The new duty factor is assumed to be 7.2%, and the authors show some results at two currents, 30 mA and 150 mA, that span the range of interest. Their superconducting linac concept consists of individual multicell cavities, each driven by a klystrode. Focusing would be provided by superconducting quadrupole lenses between cavities. In the remainder of the paper they describe their study to evaluate the potential of a superconducting proton linac section for this application, and address some of the many design choices.

  1. Phosphate concentration and association as revealed by sequential extraction and microprobe analysis: The case of sediments from two Argentinean reservoirs

    NASA Astrophysics Data System (ADS)

    Borgnino, L.; Orona, C.; Avena, M.; Maine, M. A.; RodríGuez, A.; de Pauli, C. P.

    2006-01-01

    This article reports the general characteristics of the sediments of two Argentinean reservoirs, which are used for water supply. The chemical composition, granulometry, and specific surface area are presented together with a study of total phosphate concentration and phosphate association by combining sequential extraction and microprobe analysis. In general, the sediments of both reservoirs have similar characteristics. Sequential extraction reveals that the main P fractions in the studied sediments are Ca-bound phosphate in river mouths and Fe-bound phosphate in the rest of the reservoir stations. Microprobe analysis appears to be an important complementary technique to sequential extraction. Combined with chemical fractionation and specific surface area measurements, these analyses indicate that Ca-bound phosphate is mainly distributed within grains or particles highly concentrated in Ca and P, whereas Fe-bound phosphate is rather homogeneously distributed in the sediments at the surface of fine particles. Microprobe analyses also revealed an important coating of phyllosilicate surfaces with Fe (hydr)oxides, which explains the good correlation found between Fe-bound phosphate, clay fraction, and specific surface area. The role of sediments as a potential source of phosphate is discussed in terms of P association in the solid phase and dissolved oxygen concentration profiles in the water column.

  2. Superconductive microprobes for eddy current evaluation of materials

    NASA Astrophysics Data System (ADS)

    Podney, Walter N.

    1989-07-01

    Superconductive quantum interference devices (SQUIDS) offer new technology for locating materials flaws electromagnetically that promises to increase sensitivity, depth of magnetic flux enables use of microscopic pickup loops in a gradiometer configuration to give high resolution. A cryogenic umbilical connects pickup loops to a remote cryostat housing SQUID sensors to ease scanning. A pair of drive coils a few millimeters in radius that encircle pickup loops forming a coplanar gradiometer 1 mm or less in radius comprise a superconductive microprobe. It provides a depth of field of several millimeters to a 0.1 mm flaw in an aluminum plate, when operating with a drive current a 1 A oscillating at a frequency of 1kHz. Its field of view ranges to several millimeters, for flaws a few millimeters deep, and its horizontal resolution is 1 mm or so, for flaw depths out to its depth of field. An array of microprobes form receptors much like rods in the retina of a magnetic eye. The eye leads to an electromagnetic microscope for imaging internal flaws in aluminum plates. It gives multiple images that enable resolving depth of a 0.1 mm flaw to a few tenths of a millimeter with a horizontal resolution of one millimeter or so.

  3. Microprobe analysis of teeth by synchrotron radiation: environmental contamination

    NASA Astrophysics Data System (ADS)

    Pinheiro, T.; Carvalho, M. L.; Casaca, C.; Barreiros, M. A.; Cunha, A. S.; Chevallier, P.

    1999-10-01

    An X-ray fluorescence set-up with microprobe capabilities, installed at the Laboratoire pour l'Utilisation du Rayonnement Électromagnétique (LURE) synchrotron (France) was used for elemental determination in teeth. To evaluate the influence of living habits in dental elemental composition nine teeth collected post-mortem were analysed, five from a miner and four from a fisherman. All teeth from the fisherman were healthy. From the miner some teeth were carious and one of them was filled with metallic amalgam. Teeth were sliced under the vertical plane and each slice was scanned from the root to the enamel for elemental profile determination. The synchrotron microprobe resolution was of 100 μm and incident photons of 18 keV energy were used. The elemental concentration values found suggest heterogeneity of the teeth material. Moreover, the distinct profiles for Mn, Sr, Br and Pb were found when teeth from the miner and from the fisherman are compared which can be associated with dietary habits and environmental influence. Higher concentrations of Mn and Sr were found for the fisherman teeth. In addition, Br was only observed in this group of teeth. Pb levels are higher for the miner teeth in particular for dentine regions. The influence of amalgam, such as, increase of Zn and Hg contents in the teeth material, is only noticed for the immediate surroundings of the treated cavity.

  4. Structural stability of anhydrous proton conducting SrZr0.9Er0.1O3-δ perovskite ceramic vs. protonation/deprotonation cycling: Neutron diffraction and Raman studies

    NASA Astrophysics Data System (ADS)

    Slodczyk, Aneta; Colomban, Philippe; Upasen, Settakorn; Grasset, Frédéric; André, Gilles

    2015-08-01

    Long-term chemical and structural stability of an ion conducting ceramic is one of the main criteria for its selection as an electrolytic membrane in energy plant devices. Consequently, medium density SrZr0.9Er0.1O3-δ (SZE) anhydrous proton conducting ceramic - a potential electrolyte of SOFC/PCFC, was analysed by neutron diffraction between room temperature and 900 °C. After the first heating/cooling cycle, the ceramic pieces were exposed to water vapour pressure in an autoclave (500 °C, 40 bar, 7 days) in order to incorporate protonic species; the protonated compound was then again analysed by neutron diffraction. This procedure was repeated two times. At each step, the sample was also controlled by TGA and Raman spectroscopy. These studies allow the first comprehensive comparison of structural and chemical stability during the protonation/deprotonation cycling. The results reveal good structural stability, although an irreversible small contraction of the unit-cell volume and local structure modifications near Zr/ErO5[] octahedra are detected after the first protonation. After the second protonation easy ceramic crumbling under a stress is observed because of the presence of secondary phases (SrCO3, Sr(OH)2) well detected by Raman scattering and TGA. The role of crystallographic purity, substituting element and residual porosity in the proton conducting perovskite electrolyte stability is discussed.

  5. Results from an Orion proton heating experiment for Warm Dense Matter studies

    NASA Astrophysics Data System (ADS)

    Allan, Peter; James, Steven; Brown, Colin; Hobbs, Lauren; Hill, Matthew; Hoarty, David; Chen, Hui; Hazi, Andy; AWE Team; LLNL Team

    2014-10-01

    The properties of warm dense matter covering densities and temperatures in the ranges 0.1-10x solid and 1-100eV, fall between ideal plasma and condensed matter theories. Studies have highlighted uncertainties in EoS predictions using methods based on the Thomas-Fermi and ion-cell models. In particular, such models predict large departures from ideal gas behaviour for low Z material at low densities and temperatures. In an extension of previous work, material has been isochorically heated using short-pulse laser-generated proton beams. Here, the method of Foord et al. was used toinfer isentropes oflow Z materials and provide data to validate model predictions. Earlier measurements were limited by the eV backlighterenergy to relatively low densities and pressures below 1.5Mbar, and were conducted in cylindrical geometry. More recent experiments performed at the Orion laser use a parabolic crystal imaging system in order to measure to higher pressures by probing planar expansion of aluminium foils at 1.8keV. The imaging system is described and results are presented showing a spatial resolution of 6um, which was then streaked to give temporal resolution of 10ps. Preliminary analysis of the foil expansion indicates a peak temperature of 30eV. The proton and ion spectra used to heat the sample were measured by a magnetic spectrometer and a Thomson parabola. These results are presented and the effect on the measured expansion discussed. Plans for future measurements are discussed in the light of results obtained so far.

  6. SU-E-T-337: Treatment Planning Study of Craniospinal Irradiation with Spot Scanning Proton Therapy

    SciTech Connect

    Tasson, A; Beltran, C; Laack, N; Childs, S; Tryggestad, E; Whitaker, T

    2014-06-01

    Purpose: To develop a treatment planning technique that achieves optimal robustness against systematic position and range uncertainties, and interfield position errors for craniospinal irradiation (CSI) using spot scanning proton radiotherapy. Methods: Eighteen CSI patients who had previously been treated using photon radiation were used for this study. Eight patients were less than 10 years old. The prescription dose was 23.4Gy in 1.8Gy fractions. Two different field arrangement types were investigated: 1 posterior field per isocenter and 2 posterior oblique fields per isocenter. For each field type, two delivery configurations were used: 5cm bolus attached to the treatment table and a 4.5cm range shifter located inside the nozzle. The target for each plan was the whole brain and thecal sac. For children under the age of 10, all plan types were repeated with an additional dose of 21Gy prescribed to the vertebral bodies. Treatment fields were matched by stepping down the dose in 10% increments over 9cm. Robustness against 3% and 3mm uncertainties, as well as a 3mm inter-field error was analyzed. Dose coverage of the target and critical structure sparing for each plan type will be considered. Ease of planning and treatment delivery was also considered for each plan type. Results: The mean dose volume histograms show that the bolus plan with posterior beams gave the best overall plan, and all proton plans were comparable to or better than the photon plans. The plan type that was the most robust against the imposed uncertainties was also the bolus plan with posterior beams. This is also the plan configuration that is the easiest to deliver and plan. Conclusion: The bolus plan with posterior beams achieved optimal robustness against systematic position and range uncertainties, as well as inter-field position errors.

  7. Linear Energy Transfer-Guided Optimization in Intensity Modulated Proton Therapy: Feasibility Study and Clinical Potential

    SciTech Connect

    Giantsoudi, Drosoula; Grassberger, Clemens; Craft, David; Niemierko, Andrzej; Trofimov, Alexei; Paganetti, Harald

    2013-09-01

    Purpose: To investigate the feasibility and potential clinical benefit of linear energy transfer (LET) guided plan optimization in intensity modulated proton therapy (IMPT). Methods and Materials: A multicriteria optimization (MCO) module was used to generate a series of Pareto-optimal IMPT base plans (BPs), corresponding to defined objectives, for 5 patients with head-and-neck cancer and 2 with pancreatic cancer. A Monte Carlo platform was used to calculate dose and LET distributions for each BP. A custom-designed MCO navigation module allowed the user to interpolate between BPs to produce deliverable Pareto-optimal solutions. Differences among the BPs were evaluated for each patient, based on dose–volume and LET–volume histograms and 3-dimensional distributions. An LET-based relative biological effectiveness (RBE) model was used to evaluate the potential clinical benefit when navigating the space of Pareto-optimal BPs. Results: The mean LET values for the target varied up to 30% among the BPs for the head-and-neck patients and up to 14% for the pancreatic cancer patients. Variations were more prominent in organs at risk (OARs), where mean LET values differed by a factor of up to 2 among the BPs for the same patient. An inverse relation between dose and LET distributions for the OARs was typically observed. Accounting for LET-dependent variable RBE values, a potential improvement on RBE-weighted dose of up to 40%, averaged over several structures under study, was noticed during MCO navigation. Conclusions: We present a novel strategy for optimizing proton therapy to maximize dose-averaged LET in tumor targets while simultaneously minimizing dose-averaged LET in normal tissue structures. MCO BPs show substantial LET variations, leading to potentially significant differences in RBE-weighted doses. Pareto-surface navigation, using both dose and LET distributions for guidance, provides the means for evaluating a large variety of deliverable plans and aids in

  8. Proton-binding study of standard and reference fulvic acids, humic acids, and natural organic matter

    NASA Astrophysics Data System (ADS)

    Ritchie, Jason D.; Perdue, E. Michael

    2003-01-01

    The acid-base properties of 14 standard and reference materials from the International Humic Substances Society (IHSS) were investigated by potentiometric titration. Titrations were conducted in 0.1 M NaCl under a nitrogen atmosphere, averaging 30 min from start to finish. Concentrations of carboxyl groups and phenolic groups were estimated directly from titration curves. Titration data were also fit to a modified Henderson-Hasselbalch model for two classes of proton-binding sites to obtain "best fit" parameters that describe proton-binding curves for the samples. The model was chosen for its simplicity, its ease of implementation in computer spreadsheets, and its excellent ability to describe the shapes of the titration curves. The carboxyl contents of the IHSS samples are in the general order: terrestrial fulvic acids > aquatic fulvic acids > Suwannee River natural organic matter (NOM) > aquatic humic acids > terrestrial humic acids. Overall, fulvic acids and humic acids have similar phenolic contents; however, all of the aquatically derived samples have higher phenolic contents than the terrestrially derived samples. The acid-base properties of reference Suwannee River NOM are surprisingly similar to those of standard Suwannee River humic acid. Results from titrations in this study were compared with other published results from both direct and indirect titrations. Typically, carboxyl contents for the IHSS samples were in agreement with the results from both methods of titration. Phenolic contents for the IHSS samples were comparable to those determined by direct titrations, but were significantly less than estimates of phenolic content that were based on indirect titrations with Ba(OH) 2 and Ca(OAc) 2. The average phenolic-to-carboxylic ratio of the IHSS samples is approximately 1:4. Models that assume a 1:2 ratio of phenolic-to-carboxylic groups may overestimate the relative contribution of phenolic groups to the acid-base chemistry of humic substances.

  9. Enantioselective Protonation

    PubMed Central

    Mohr, Justin T.; Hong, Allen Y.; Stoltz, Brian M.

    2010-01-01

    Enantioselective protonation is a common process in biosynthetic sequences. The decarboxylase and esterase enzymes that effect this valuable transformation are able to control both the steric environment around the proton acceptor (typically an enolate) and the proton donor (typically a thiol). Recently, several chemical methods to achieve enantioselective protonation have been developed by exploiting various means of enantiocontrol in different mechanisms. These laboratory transformations have proven useful for the preparation of a number of valuable organic compounds. PMID:20428461

  10. Intramolecular photoinduced proton transfer in 2-(2‧-hydroxyphenyl)benzazole family: A TD-DFT quantum chemical study

    NASA Astrophysics Data System (ADS)

    Roohi, Hossein; Mohtamedifar, Nafiseh; Hejazi, Fahemeh

    2014-11-01

    In this work, intramolecular photoinduced proton transfer in 2-(2‧-hydroxyphenyl)benzazole family (HBO, HBI and HBT) was investigated using TD-DFT calculations at PBE1PBE/6-311++G(2d,2p) level of theory. The potential energy surfaces were employed to explore the proton transfer reactions in both states. In contrast to the ground state, photoexcitation from S0 state to S1 one encourages the operation of the excited-state intramolecular proton transfer process. Structural parameters, H-bonding energy, absorption and emission bands, vertical excitation and emission energies, oscillator strength, fluorescence rate constant, dipole moment, atomic charges and electron density at critical points were calculated. Molecular orbital analysis shows that vertical S0 → S1 transition in the studied molecules corresponds essentially to the excitation from HOMO (π) to LUMO (π∗). Our calculated results are in good agreement with the experimental observations.

  11. Study of radiation induced deep-level defects in proton irradiated AlGaAs-GaAs solar cells

    NASA Technical Reports Server (NTRS)

    Li, S. S.

    1980-01-01

    Radiation induced deep-level defects (both electron and hole traps) in proton irradiated AlGaAs-GaAs p-n junction solar cells are investigated along with the correlation between the measured defect parameters and the solar cell performance parameters. The range of proton energies studied was from 50 KeV to 10 MeV and the proton fluence was varied from 10 to the 10th power to 10 to the 13th power P/sq cm. Experimental tools employed include deep-level transient spectroscopy, capacitance-voltage, current voltage, and SEM-EBIC methods. Defect and recombination parameters such as defect density and energy level, capture cross section, carrier lifetimes and effective hole diffusion lengths in n-GaAs LPE layers were determined from these measurements.

  12. Quantum Mechanics Studies of Fuel Cell Catalysts and Proton Conducting Ceramics with Validation by Experiment

    NASA Astrophysics Data System (ADS)

    Tsai, Ho-Cheng

    We carried out quantum mechanics (QM) studies aimed at improving the performance of hydrogen fuel cells. In part I, The challenge was to find a replacement for the Pt cathode that would lead to improved performance for the Oxygen Reduction Reaction (ORR) while remaining stable under operational conditions and decreasing cost. Our design strategy was to find an alloy with composition Pt3M that would lead to surface segregation such that the top layer would be pure Pt, with the second and subsequent layers richer in M. Under operating conditions we expect the surface to have significant O and/or OH chemisorbed on the surface; we searched for M that would remain segregated under these conditions. Using QM we examined surface segregation for 28 Pt3M alloys, where M is a transition metal. We found that only Pt3Os and Pt3Ir showed significant surface segregation when O and OH are chemisorbed on the catalyst surfaces. This result indicates that Pt3Os and Pt 3Ir favor formation of a Pt-skin surface layer structure that would resist the acidic electrolyte corrosion during fuel cell operation environments. We chose to focus on Os because the phase diagram for Pt-Ir indicated that Pt-Ir could not form a homogeneous alloy at lower temperature. To determine the performance for ORR, we used QM to examine intermediates, reaction pathways, and reaction barriers involved in the processes for which protons from the anode reactions react with O2 to form H2O. These QM calculations used our Poisson-Boltzmann implicit solvation model include the effects of the solvent (water with dielectric constant 78 with pH 7 at 298K). We also carried out similar QM studies followed by experimental validation for the Os/Pt core-shell catalyst fabricated by the underpotential deposition (UPD) method. The QM results indicated that the RDS for ORR is a compromise between the OOH formation step (0.37 eV for Pt, 0.23 eV for Pt2ML/Os core-shell) and H2O formation steps (0.32 eV for Pt, 0.22 eV for Pt2ML

  13. Chemical and Isotopic Analysis of Trace Organic Matter on Meteorites and Interstellar Dust Using a Laser Microprobe Instrument

    NASA Technical Reports Server (NTRS)

    Zare, Richard N.; Boyce, Joseph M. (Technical Monitor)

    2001-01-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are of considerable interest today because they are ubiquitous on Earth and in the interstellar medium (ISM). In fact, about 20% of cosmic carbon in the galaxy is estimated to be in the form of PAHs. Investigation of these species has obvious uses for determining the cosmochemistry of the solar system. Work in this laboratory has focused on four main areas: 1) Mapping the spatial distribution of PAHs in a variety of meteoritic samples and comparing this distribution with mineralogical features of the meteorite to determine whether a correlation exists between the two. 2) Developing a method for detection of fullerenes in extraterrestrial samples using microprobe Laser Desorption Ionization Mass Spectroscopy and utilizing this technique to investigate fullerene presence, while exploring the possibility of spatially mapping the fullerene distribution in these samples through in situ detection. 3) Investigating a possible formation pathway for meteoritic and ancient terrestrial kerogen involving the photochemical reactions of PAHs with alkanes under prebiotic and astrophysically relevant conditions. 4) Studying reaction pathways and identifying the photoproducts generated during the photochemical evolution of PAH-containing interstellar ice analogs as part of an ongoing collaboration with researchers at the Astrochemistry Lab at NASA Ames. All areas involve elucidation of the solar system formation and chemistry using microprobe Laser Desorption Laser Ionization Mass Spectrometry. A brief description of microprobe Laser Desorption Ionization Mass Spectroscopy, which allows selective investigation of subattomole levels of organic species on the surface of a sample at 10-40 micrometer spatial resolution, is given.

  14. IR-Spectroscopic Study of Hydrogen Bonds in n-Butanol and its Mixtures with Various Proton Acceptors

    NASA Astrophysics Data System (ADS)

    Zaverkina, M. A.; Lodygina, V. P.; Badamshina, E. R.

    2014-03-01

    Absorption bands corresponding to all types of hydroxyl associates [νas = 3476 cm-1 (OH…OH); νas = 3472 cm-1 (OH…N3); and νas = 3457 cm-1 (OH…O)] were assigned using IR spectroscopy in CH2Cl2 and n-butanol and its mixtures with various proton acceptors (THF, hexylazide, azide-containing oxetane monomers). The order of concentrations for these associates was . Equilibrium formation constants were estimated quantitatively. The proton-acceptor abilities of the studied additives were established.

  15. A statistical study of proton pitch angle distributions measured by the Radiation Belt Storm Probes Ion Composition Experiment

    NASA Astrophysics Data System (ADS)

    Shi, Run; Summers, Danny; Ni, Binbin; Manweiler, Jerry W.; Mitchell, Donald G.; Lanzerotti, Louis J.

    2016-06-01

    A statistical study of ring current-energy proton pitch angle distributions (PADs) in Earth's inner magnetosphere is reported here. The data are from the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on board the Van Allen Probe B spacecraft from 1 January 2013 to 15 April 2015. By fitting the data to the functional form sinnα, where α is the proton pitch angle, we examine proton PADs at the energies 50, 100, 180, 328, and 488 keV in the L shell range from L = 2.5 to L = 6. Three PAD types are classified: trapped (90° peaked), butterfly, and isotropic. The proton PAD dependence on the particle energy, magnetic local time (MLT), L shell, and geomagnetic activity are analyzed in detail. The results show a strong dependence of the proton PADs on MLT. On the nightside, the n values outside the plasmapause are clearly lower than those inside the plasmapause. At higher energies and during intense magnetic activity, nightside butterfly PADs can be observed at L shells down to the vicinity of the plasmapause. The averaged n values on the dayside are larger than on the nightside. A maximum of the averaged n values occurs around L = 4.5 in the postnoon sector (12-16 MLT). The averaged n values show a dawn-dusk asymmetry with lower values on the dawnside at high L shells, which is consistent with previous studies of butterfly PADs. The MLT dependence of the proton PADs becomes more distinct with increasing particle energy. These features suggest that drift shell splitting coupled with a radial flux gradient play an important role in the formation of PADs, particularly at L > ~ 4.5.

  16. Feasibility Study of Glass Dosimeter for In Vivo Measurement: Dosimetric Characterization and Clinical Application in Proton Beams

    SciTech Connect

    Rah, Jeong-Eun; Oh, Do Hoon; Kim, Jong Won; Kim, Dae-Hyun; Suh, Tae-Suk; Ji, Young Hoon; Shin, Dongho; Lee, Se Byeong; Kim, Dae Yong; Park, Sung Yong

    2012-10-01

    Purpose: To evaluate the suitability of the GD-301 glass dosimeter for in vivo dose verification in proton therapy. Methods and Materials: The glass dosimeter was analyzed for its dosimetrics characteristic in proton beam. Dosimeters were calibrated in a water phantom using a stairlike holder specially designed for this study. To determine the accuracy of the glass dosimeter in proton dose measurements, we compared the glass dosimeter and thermoluminescent dosimeter (TLD) dose measurements using a cylindrical phantom. We investigated the feasibility of the glass dosimeter for the measurement of dose distributions near the superficial region for proton therapy plans with a varying separation between the target volume and the surface of 6 patients. Results and Discussion: Uniformity was within 1.5%. The dose-response has good linearity. Dose-rate, fading, and energy dependence were found to be within 3%. The beam profile measured using the glass dosimeter was in good agreement with the profile obtained from the ionization chamber. Depth-dose distributions in nonmodulated and modulated proton beams obtained with the glass dosimeter were estimated to be within 3%, which was lower than those with the ionization chamber. In the phantom study, the difference of isocenter dose between the delivery dose calculated by the treatment planning system and that measured by the glass dosimeter was within 5%. With in vivo dosimetry, the calculated surface doses overestimated measurements by 4%-16% using glass dosimeter and TLD. Conclusion: It is recommended that bolus be added for these clinical cases. We also believe that the glass dosimeter has considerable potential for use with in vivo patient proton dosimetry.

  17. Status of experimental studies of electron cloud effects at the Los Alamos proton storage ring

    SciTech Connect

    Macek, R. J.; Browman, A. A.; Borden, M. J.; Fitzgerald, D. H.; McCrady, R. C.; Spickermann, T. J.; Zaugg, T. J.

    2004-01-01

    Various electron cloud effects (ECE) including the two-stream (e-p) instability at the Los Alamos Proton Storage Ring (PSR) have been studied extensively for the past five years with the goal of understanding the phenomena, mitigating the instability and ultimately increasing beam intensity. The specialized diagnostics used in the studies are two types of electron detectors, the retarding field analyzer and the electron sweepmg detector - which have been employed to measure characteristics of the electron cloud as functions of time, location in the ring and various influential beam parameters - plus a short stripline beam position monitor used to measure high frequency motion of the beam centroid. Highlights of this research program are summarized along with more detail on recent results obtained since the ECLOUD'02 workshop. Recent work mcludes a number of parametric studies of the various factors that affect the electron cloud signals, studies of the sources of initial or 'seed' electrons, additional observations of electron cloud dissipation after the beam pulse is extracted, studies of the 'first pulse instability' issue, more data on electron suppression as a cure for the instability, and observations of the effect of a one-turn weak kick on intense beams in the presence of a significant electron cloud.

  18. RABBIT: an electron microprobe data-reduction program using empirical corrections

    USGS Publications Warehouse

    Goff, Fraser E.

    1977-01-01

    RABBIT is a FORTRAN IV computer Program that uses Bence-Albee empirical corrections for the reduction of electron microprobe data of silicates, oxides, sulphates, carbonates, and phosphates. RABBIT efficiently reduces large volumes of data collected on 3-11 channel microprobes.

  19. Feasibility study of the neutron dose for real-time image-guided proton therapy: A Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Kim, Jin Sung; Shin, Jung Suk; Kim, Daehyun; Shin, Eunhyuk; Chung, Kwangzoo; Cho, Sungkoo; Ahn, Sung Hwan; Ju, Sanggyu; Chung, Yoonsun; Jung, Sang Hoon; Han, Youngyih

    2015-07-01

    Two full rotating gantries with different nozzles (multipurpose nozzle with MLC, scanning dedicated nozzle) for a conventional cyclotron system are installed and being commissioned for various proton treatment options at Samsung Medical Center in Korea. The purpose of this study is to use Monte Carlo simulation to investigate the neutron dose equivalent per therapeutic dose, H/D, for X-ray imaging equipment under various treatment conditions. At first, we investigated the H/D for various modifications of the beamline devices (scattering, scanning, multi-leaf collimator, aperture, compensator) at the isocenter and at 20, 40 and 60 cm distances from the isocenter, and we compared our results with those of other research groups. Next, we investigated the neutron dose at the X-ray equipment used for real-time imaging under various treatment conditions. Our investigation showed doses of 0.07 ~ 0.19 mSv/Gy at the X-ray imaging equipment, depending on the treatment option and interestingly, the 50% neutron dose reduction was observed due to multileaf collimator during proton scanning treatment with the multipurpose nozzle. In future studies, we plan to measure the neutron dose experimentally and to validate the simulation data for X-ray imaging equipment for use as an additional neutron dose reduction method.

  20. Proton Pump Inhibitor Use and Magnesium Concentrations in Hemodialysis Patients: A Cross-Sectional Study

    PubMed Central

    Nakashima, Akio; Ohkido, Ichiro; Yokoyama, Keitaro; Mafune, Aki; Urashima, Mitsuyoshi; Yokoo, Takashi

    2015-01-01

    Magnesium concentration is a proven predictor of mortality in hemodialysis patients. Recent reports have indicated that proton pump inhibitor (PPI) use affects serum magnesium levels, however few studies have investigated the relationship between PPI use and magnesium levels in hemodialysis patients. This study aimed to clarify the association between PPI use and serum magnesium levels in hemodialysis patients. We designed this cross sectional study and included 1189 hemodialysis patients in stable condition. Associations between PPI and magnesium-related factors, as well as other possible confounders, were evaluated using a multiple regression model. We defined hypomagnesemia as a value < 2.0 mg/dL, and created comparable logistic regression models to assess the association between PPI use and hypomagnesemia. PPI use is associated with a significantly lower mean serum magnesium level than histamine 2 (H2) receptor antagonists or no acid-suppressive medications (mean [SD] PPI: 2.52 [0.45] mg/dL; H2 receptor antagonist: 2.68 [0.41] mg/dL; no acid suppressive medications: 2.68 [0.46] mg/dL; P = 0.001). Hypomagnesemia remained significantly associated with PPI (adjusted OR, OR: 2.05; 95% CI: 1.14–3.69; P = 0.017). PPI use is associated with an increased risk of hypomagnesemia in hemodialysis patients. Future prospective studies are needed to explore magnesium replacement in PPI users on hemodialysis. PMID:26618538

  1. Development and applications of an epifluorescence module for synchrotron x-ray fluorescence microprobe imaging

    SciTech Connect

    Miller, Lisa M.; Smith, Randy J.; Ruppel, Meghan E.; Ott, Cassandra H.; Lanzirotti, Antonio

    2005-06-15

    Synchrotron x-ray fluorescence (XRF) microprobe is a valuable analysis tool for imaging trace element composition in situ at a resolution of a few microns. Frequently, epifluorescence microscopy is beneficial for identifying the region of interest. To date, combining epifluorescence microscopy with x-ray microprobe has involved analyses with two different microscopes. We report the development of an epifluorescence module that is integrated into a synchrotron XRF microprobe beamline, such that visible fluorescence from a sample can be viewed while collecting x-ray microprobe images simultaneously. This unique combination has been used to identify metal accumulation in Alzheimer's disease plaques and the mineral distribution in geological samples. The flexibility of this accessory permits its use on almost any synchrotron x-ray fluorescence microprobe beamline and applications in many fields of science can benefit from this technology.

  2. 3D reconstruction of scintillation light emission from proton pencil beams using limited viewing angles-a simulation study.

    PubMed

    Hui, CheukKai; Robertson, Daniel; Beddar, Sam

    2014-08-21

    An accurate and high-resolution quality assurance (QA) method for proton radiotherapy beams is necessary to ensure correct dose delivery to the target. Detectors based on a large volume of liquid scintillator have shown great promise in providing fast and high-resolution measurements of proton treatment fields. However, previous work with these detectors has been limited to two-dimensional measurements, and the quantitative measurement of dose distributions was lacking. The purpose of the current study is to assess the feasibility of reconstructing three-dimensional (3D) scintillation light distributions of spot scanning proton beams using a scintillation system. The proposed system consists of a tank of liquid scintillator imaged by charge-coupled device cameras at three orthogonal viewing angles. Because of the limited number of viewing angles, we developed a profile-based technique to obtain an initial estimate that can improve the quality of the 3D reconstruction. We found that our proposed scintillator system and profile-based technique can reconstruct a single energy proton beam in 3D with a gamma passing rate (3%/3 mm local) of 100.0%. For a single energy layer of an intensity modulated proton therapy prostate treatment plan, the proposed method can reconstruct the 3D light distribution with a gamma pass rate (3%/3 mm local) of 99.7%. In addition, we also found that the proposed method is effective in detecting errors in the treatment plan, indicating that it can be a very useful tool for 3D proton beam QA. PMID:25054735

  3. 3D reconstruction of scintillation light emission from proton pencil beams using limited viewing angles—a simulation study

    NASA Astrophysics Data System (ADS)

    Hui, CheukKai; Robertson, Daniel; Beddar, Sam

    2014-08-01

    An accurate and high-resolution quality assurance (QA) method for proton radiotherapy beams is necessary to ensure correct dose delivery to the target. Detectors based on a large volume of liquid scintillator have shown great promise in providing fast and high-resolution measurements of proton treatment fields. However, previous work with these detectors has been limited to two-dimensional measurements, and the quantitative measurement of dose distributions was lacking. The purpose of the current study is to assess the feasibility of reconstructing three-dimensional (3D) scintillation light distributions of spot scanning proton beams using a scintillation system. The proposed system consists of a tank of liquid scintillator imaged by charge-coupled device cameras at three orthogonal viewing angles. Because of the limited number of viewing angles, we developed a profile-based technique to obtain an initial estimate that can improve the quality of the 3D reconstruction. We found that our proposed scintillator system and profile-based technique can reconstruct a single energy proton beam in 3D with a gamma passing rate (3%/3 mm local) of 100.0%. For a single energy layer of an intensity modulated proton therapy prostate treatment plan, the proposed method can reconstruct the 3D light distribution with a gamma pass rate (3%/3 mm local) of 99.7%. In addition, we also found that the proposed method is effective in detecting errors in the treatment plan, indicating that it can be a very useful tool for 3D proton beam QA.

  4. A Comparative Ab Initio Study of the Primary Hydration and Proton Dissociation of Various Imide and Sulfonic Acid Ionomers

    SciTech Connect

    Clark II, Jeffrey K.; Paddison, Stephen J.; Eikerling, Michael; Dupuis, Michel; Zawodzinski, Jr., Thomas A.

    2012-03-29

    We compare the role of neighboring group substitutions on proton dissociation of hydrated acidic moieties suitable for proton exchange membranes through electronic structure calculations. Three pairs of ionomers containing similar electron withdrawing groups within the pair were chosen for the study: two fully fluorinated sulfonyl imides (CF3SO2NHSO2CF3 and CF3CF2SO2NHSO2CF3), two partially fluorinated sulfonyl imides (CH3SO2NHSO2CF3 and C6H5SO2NHSO2CF2CF3), and two aromatic sulfonic acid based material s (CH3C6H4SO3H and CH3 OC6 - H3OCH3C6H4SO3H). Fully optimized counterpoise (CP) corrected geometries were obtained for each ionomer fragment with the inclusion of water molecules at the B3LYP/6-311G** level of density functional theory. Spontaneous proton dissociation was observed upon addition of three water molecules in each system, and the transition to a solvent-separated ion pair occurred when four water molecules were introduced. No considerable quantitative or qualitative differences in proton dissociation, hydrogen bond networks formed, or water binding energies were found between systems containing similar electron withdrawing groups. Each of the sulfonyl imide ionomers exhibited qualitatively similar results regarding proton dissociation and separation. The fully fluorinated sulfonyl imides, however, showed a greater propensity to exist in dissociated and ion-pair separated states at low degrees of hydration than the partially fluorinated sulfonyl imides. This effect is due to the additional electron withdrawing groups providing charge stabilization as the dissociated proton migrates away from the imide anion.

  5. A dash of protons: A theoretical study on the hydrolysis mechanism of 1-substitued silatranes and their protonated analogs

    SciTech Connect

    Sok, Sarom; Gordon, Mark

    2011-08-17

    Ab initio calculations were carried out to study the hydrolysis mechanism of 1-substituted silatranes in the presence of an acid (acid-catalyzed) and an additional water (water-assisted). Compared with the neutral hydrolysis mechanism involving one water, use of an acid catalyst reduces the barrier associated with the rate-limiting step by approximate to 14 kcal/mol. A modest decrease of approximate to 5 kcal/mol is predicted when an additional water molecule is added to the neutral hydrolysis mechanism involving one water. The combination of an acid catalyst and an additional water molecule reduces the barrier by approximate to 27 kcal/mol. Bond order analysis suggests ring cleavage involving the bond breaking of a siloxane and silanol group during the neutral and acid-catalyzed hydrolysis of 1-substituted silatranes. respectively. Solvent effects, represented by the PCM continuum model, do not qualitatively alter computational gas-phase results. (C) 2011 Elsevier B.V. All rights reserved.

  6. Use of proton-pump inhibitors among adults: a Danish nationwide drug utilization study

    PubMed Central

    Pottegård, Anton; Broe, Anne; Hallas, Jesper; de Muckadell, Ove B. Schaffalitzky; Lassen, Annmarie T.; Lødrup, Anders B.

    2016-01-01

    Background: The use of proton-pump inhibitors (PPIs) has increased over the last decade. The objective of this study was to provide detailed utilization data on PPI use over time, with special emphasis on duration of PPI use and concomitant use of ulcerogenic drugs. Methods: Using the nationwide Danish Prescription Registry, we identified all Danish adults filling a PPI between 2002 and 2014. Using descriptive statistics, we reported (i) the distribution of use between single PPI entities, (ii) the development in incidence and prevalence of use over time, (iii) measures of duration and intensity of treatment, and (iv) the prevalence of use of ulcerogenic drugs among users of PPIs. Results: We identified 1,617,614 adults using PPIs during the study period. The prevalence of PPI use increased fourfold during the study period to 7.4% of all Danish adults in 2014. PPI use showed strong age dependency, reaching more than 20% among those aged at least 80 years. The proportion of users maintaining treatment over time increased with increasing age, with less than10% of those aged 18–39 years using PPIs 2 years after their first prescription, compared with about 40% among those aged at least 80 years. The overall use of ulcerogenic drugs among PPI users increased moderately, from 35% of users of PPI in 2002 to 45% in 2014. Conclusions: The use of PPIs is extensive and increasing rapidly, especially among the elderly. PMID:27582879

  7. Theoretical study of the structure and electronic spectra of fully protonated emeraldine oligomers

    NASA Astrophysics Data System (ADS)

    Zhekova, H.; Tadjer, A.; Ivanova, A.; Petrova, J.; Gospodinova, N.

    Polyaniline (PANI) is one of the most studied conducting polymers. Obtained in its conducting form (known as ?emeraldine salt?) by chemical or electrochemical oxidation of aniline in aqueous acidic medium, this polymer manifests an array of attractive properties. Nevertheless, these properties still need to be described at the molecular level. Intense theoretical investigations during the past few years aim at explaining the chain organization, conductivity mechanism, and other structural and spectral characteristics. Most studies adopt simplified models in which hydration effect is underestimated, since all simulations are performed either in vacuum or in the presence of a limited number of water molecules. The present computational study sheds light on the molecular organization of a number of model PANI hydrated clusters with different alignment and multiplicity, which can explain the experimentally recorded UV/VIS spectra. The influence of hydration and interaction with adjacent oligomers is estimated. Short-chain doubly protonated emeraldine oligomers are used as model systems. The calculations are performed at the semi-empirical (AM1) and/or molecular mechanics (AMBER96) level. Proper configurations of the clusters are selected using Monte Carlo simulations. Electron correlation (CIS) is accounted for upon evaluation of the absorption spectra of the clusters. The relative strength of the interchain coupling is estimated by simulation of PANI clusters consisting of two PANI tetramers in water. Comparison to experimental results is made.

  8. Proton transport in triflic acid hydrates studied via path integral car-parrinello molecular dynamics.

    PubMed

    Hayes, Robin L; Paddison, Stephen J; Tuckerman, Mark E

    2009-12-31

    The mono-, di-, and tetrahydrates of trifluoromethanesulfonic acid, which contain characteristic H(3)O(+), H(5)O(2)(+), and H(9)O(4)(+) structures, provide model systems for understanding proton transport in materials with high perfluorosulfonic acid density such as perfluorosulfonic acid membranes commonly employed in hydrogen fuel cells. Ab initio molecular dynamics simulations indicate that protons in these solids are predisposed to transfer to the water most strongly bound to sulfonate groups via a Grotthuss-type mechanism, but quickly return to the most solvated defect structure either due to the lack of a nearby species to stabilize the new defect or a preference for the proton to be maximally hydrated. Path integral molecular dynamics of the mono- and dihydrate reveal significant quantum effects that facilitate proton transfer to the "presolvated" water or SO(3)(-) in the first solvation shell and increase the Zundel character of all the defects. These trends are quantified in free energy profiles for each bonding environment. Hydrogen bonding criteria for HOH-OH(2) and HOH-O(3)S are extracted from the two-dimensional potential of mean force. The quantum radial distribution function, radius of gyration, and root-mean-square displacement position correlation function show that the protonic charge is distributed over two or more water molecules. Metastable structural defects with one excess proton shared between two sulfonate groups and another Zundel or Eigen type cation defect are found for the mono- and dihydrate but not for the tetrahydrate crystal. Results for the tetrahydrate native crystal exhibit minor differences at 210 and 250 K. IR spectra are calculated for all native and stable defect structures. Graph theory techniques are used to characterize the chain lengths and ring sizes in the hydrogen bond network. Low conductivities when limited water is present may be attributable to trapping of protons between SO(3)(-) groups and the increased

  9. Relaxation of water protons in highly concentrated aqueous protein systems studied by 1H NMR spectroscopy.

    PubMed

    Szuminska, K; Gutsze, A; Kowalczyk, A

    2001-01-01

    Concentrated Aqueous Protein Systems, Proton Relaxation Times, Slow Chemical Exchange In this paper we present proton spin-lattice (T1) and spin-spin (T2) relaxation times measured vs. concentration, temperature, pulse interval (tauCPMG) as well as 1H NMR spectral measurements in a wide range of concentrations of bovine serum albumin (BSA) solutions. The anomalous relaxation behaviour of the water protons, similar to that observed in mammalian lenses, was found in the two most concentrated solutions (44% and 46%). The functional dependence of the spin-spin relaxation time vs. tauCPMG pulse interval and the values of the motional activation parameters obtained from the temperature dependencies of spin-lattice relaxation times suggest that the water molecule mobility is reduced in these systems. The slow exchange process on the T2 time scale is proposed to explain the obtained data. The proton spectral measurements support the hypothesis of a slow exchange mechanism in the highest concentrated solutions. From the analysis of the shape of the proton spectra the mean exchange times between bound and bulk water proton groups (tauex) have been estimated for the range of the highest concentrations (30%-46%). The obtained values are of the order of milliseconds assuring that the slow exchange condition is fulfilled in the most concentrated samples. PMID:11837660

  10. Fundamental Studies on the Use of Laser-Driven Proton Beams for Fast Ignition

    NASA Astrophysics Data System (ADS)

    McGuffey, C.; Kim, J.; Beg, F. N.; Wei, M. S.; Chen, S. N.; Fuchs, J.; Nilson, P. M.; Theobald, W.; Habara, H.; Tanaka, K.; Yabuuchi, T.; Foord, M. E.; Patel, P. K.; McLean, H. S.; Roth, M.; McKenna, P.

    2015-11-01

    A short-pulse-laser-driven intense proton beam remains a candidate for Fast Ignition heater due to its focusability and high current. However, the proton current density necessary for FI in practice has never been produced in the laboratory and there are many physics issues that should be addressed using current and near-term facilities. For example, the extraction of sufficient proton charge from the short-pulse laser target could be evaluated with the multi-kilojoule NIF ARC laser. Transport of the beam through matter, such as a cone tip, and deposition in the fuel must be considered carefully as it will isochorically heat any material it enters and produce a rapidly-evolving, warm dense matter state with uncertain transport and stopping properties. Here we share experimental measurements of the proton spectra after passing through metal cones and foils taken with the kilojoule-class, multi-picosecond OMEGA EP and LFEX lasers. We also present complementary PIC simulations of beam generation and transport to and in the foils. Upcoming experiments to further evaluate proton beam performance in proton FI will also be outlined. This work was supported by the DOE/NNSA NLUF program, Contract DE-NA0002034 and by the AFOSR under Contract FA9550-14-1-0346.

  11. Nuclear microprobe analysis of muscle biopsies: Applications in pathology and clinic

    NASA Astrophysics Data System (ADS)

    Moretto, Ph; Coquet, M.; Gherardi, R. K.; Stoedzel, P.

    2000-03-01

    The nuclear microprobe analysis of muscle biopsy sections has been recently applied to investigate different muscle disorders. This technique, employed as a complementary examination in the frame of pathological studies, permitted to confirm the diagnosis for a first pathology and to elucidate the cause of a second. In skeletal muscles of a young patient suffering from a slow progressive myopathy, calcium accumulations have been demonstrated in histologically abnormal fibers. These findings have been compared to histopathological characteristics previously described. On the other hand, we have evaluated muscle sections from two patients who presented symptoms of an inflammatory myopathy, a rare pathology that recently emerged in France. The chemical analyses permitted us to highlight local aluminium infiltration in muscles. The hypothesis of an unusual reaction to intramuscular aluminium accumulation has been advanced. These studies demonstrate the capability for ion beam microanalytical techniques to address acute problems in pathology.

  12. Nuclear microprobe and optical investigation of sparkling wine bottles

    NASA Astrophysics Data System (ADS)

    Padayachee, J.; Prozesky, V. M.; Pineda, C. A.

    1999-10-01

    Glass bottles, used for sparkling wine, are treated with freon during manufacturing to harden the inside surface. Although this type of treatment normally improves the properties of the glass, in this case the occurrence of "egg" formations (egg-shaped rough areas) on distinct areas of bottles, as well as yeast sticking to the insides of bottles at specific areas pointed to the possibility of different areas showing different properties in the same bottle. The question was whether the correct gas was used for the treatment, and secondly, whether the process was controlled well enough to obtain the correct properties for the inside of the glass. We present results of an optical microscopy and nuclear microprobe (NMP) investigation.

  13. Thin film characterization using a mechanical properties microprobe

    NASA Astrophysics Data System (ADS)

    Oliver, W. C.; McHargue, C. J.; Zinkle, S. J.

    A new ultra-low load microindentation system has been acquired in the ORNL Metals and Ceramics Division. The system's spatial resolution and its data acquisition capabilities allow the determination of several mechanical properties from volumes of material with submicron dimension; hence, the term Mechanical Properties Microprobe (MPM). Research with the MPM at Oak Ridge has led to improved techniques for determining the plastic and elastic properties of materials using microindentation experiments. The techniques have been applied to thin films created by ion implanting metals and ceramics, radiation damaged materials, and thin hard coatings of TiN. Changes in the strength (hardness) and modulus have been measured in films as thin as 200 nm.

  14. Secondary ion collection and transport system for ion microprobe

    DOEpatents

    Ward, James W.; Schlanger, Herbert; McNulty, Jr., Hugh; Parker, Norman W.

    1985-01-01

    A secondary ion collection and transport system, for use with an ion microprobe, which is very compact and occupies only a small working distance, thereby enabling the primary ion beam to have a short focal length and high resolution. Ions sputtered from the target surface by the primary beam's impact are collected between two arcuate members having radii of curvature and applied voltages that cause only ions within a specified energy band to be collected. The collected ions are accelerated and focused in a transport section consisting of a plurality of spaced conductive members which are coaxial with and distributed along the desired ion path. Relatively high voltages are applied to alternate transport sections to produce accelerating electric fields sufficient to transport the ions through the section to an ion mass analyzer, while lower voltages are applied to the other transport sections to focus the ions and bring their velocity to a level compatible with the analyzing apparatus.

  15. Implementation of ionoluminescence in the AGLAE scanning external microprobe

    NASA Astrophysics Data System (ADS)

    Pichon, L.; Calligaro, T.; Gonzalez, V.; Lemasson, Q.; Moignard, B.; Pacheco, C.

    2015-04-01

    The scope of this work is to present the implementation of an IBIL imaging system in the scanning external microprobe of the AGLAE facility so as to correlate luminescence and composition maps provided by PIXE, RBS and PIGE. The challenging integration of the optical spectrometer, due to incompatibility of acquisition timings and data formats with the other IBA channels has motivated the development of a specific acquisition system. This article details the IBIL setup and explains the technical solutions retained for the coupling of IBIL with IBA techniques in order to produce fast and large IBIL-IBA maps. The IBIL maps stored in the same format as the PIXE, RBS and PIGE ones can be visualised and compared using the dedicated AGLAEmap program or the PyMCA processing package. An example of such a coupled mapping on Mesoamerican jade is presented to emphasise the interest of performing simultaneously IBA and IBIL large mappings.

  16. Proton transfer in organic scaffolds

    NASA Astrophysics Data System (ADS)

    Basak, Dipankar

    This dissertation focuses on the fundamental understanding of the proton transfer process and translating the knowledge into design/development of new organic materials for efficient non-aqueous proton transport. For example, what controls the shuttling of a proton between two basic sites? a) Distance between two groups? or b) the basicity? c) What is the impact of protonation on molecular conformation when the basic sites are attached to rigid scaffolds? For this purpose, we developed several tunable proton sponges and studied proton transfer in these scaffolds theoretically as well as experimentally. Next we moved our attention to understand long-range proton conduction or proton transport. We introduced liquid crystalline (LC) proton conductor based on triphenylene molecule and established that activation energy barrier for proton transport is lower in the LC phase compared to the crystalline phase. Furthermore, we investigated the impact of several critical factors: the choice of the proton transferring groups, mobility of the charge carriers, intrinsic vs. extrinsic charge carrier concentrations and the molecular architectures on long-range proton transport. The outcome of this research will lead to a deeper understanding of non-aqueous proton transfer process and aid the design of next generation proton exchange membrane (PEM) for fuel cell.

  17. Studies on the mechanism of action of triphenyltin on proton conduction by the H+-ATPase of mitochondria.

    PubMed

    Papa, S; Guerrieri, F; de Gomez Puyou, M T; Barranco, J; Gomez Puyou, A

    1982-11-01

    A study is presented of the action of triphenyltin on the kinetics of the anaerobic relaxation of the proton gradient set up by respiration in various type of 'inside-out' inner membrane vesicles obtained by exposure of beef-heart mitochondria to ultrasonic energy. Triphenyltin is shown to act as a powerful inhibitor of the proton conductivity of the H+-ATPase. The inhibition persists after removal of the ATPase protein inhibitor, F1 and the oligomycin-sensitivity conferral protein (OSCP) from the particles. The inhibitory effect of triphenyltin is exerted, as in the case of oligomycin and N,N'-dicyclohexylcarbodiimide, on the F0 moiety of the ATPase complex. Comparison of the characteristics of the effect of triphenyltin on proton translocation in chloride and nitrate media shows that the inhibition of passive proton conductivity studied here is unrelated to the hydroxide/anion exchange induced by the organotin. Lack of additivity of the inhibition of H+ conduction by triphenyltin with that exerted by oligomycin and N,N'-dicyclohexylcarbodiimide and the kinetic pattern of the effect of triphenyltin show that the mechanism of action of the organotin is different from that of the other two inhibitors. The relevance of the results obtained with respect to the subunit location and chemical nature of the reaction site of triphenyltin in the H+-ATPase complex is discussed. PMID:6293821

  18. Thermal hydraulic studies of spallation target for one-way coupled Indian accelerator driven systems with low energy proton beam

    NASA Astrophysics Data System (ADS)

    Mantha, V.; Mohanty, A. K.; Satyamurthy, P.

    2007-02-01

    BARC has recently proposed a one-way coupled ADS reactor. This reactor requires typically 1 GeV proton beam with 2 mA of current. Approximately 8 kW of heat is deposited in the window of the target. Circulating liquid metal target (lead/lead-bismuth{eutectic) has to extract this heat and this is a critical R&D problem to be solved. At present there are very few accelerators, which can give few mA and high-energy proton beam. However, accelerators with low energy and hundreds of micro-ampere current are commercially available. In view of this, it is proposed in this paper to simulate beam window heating of 8 kW in the target with low-energy proton beam. Detailed thermal analysis in the spallation and window region has been carried out to study the capability of heat extraction by circulating LBE for a typical target loop with a proton beam of 30 MeV energy and current of 0.267 mA. The heat deposition study is carried out using FLUKA code and flow analysis by CFD code. The detailed analysis of this work is presented in this paper.

  19. Deep Space 2: The Mars Microprobe Project and Beyond

    NASA Technical Reports Server (NTRS)

    Smrekar, S. E.; Gavit, S. A.

    1998-01-01

    The Mars Microprobe Project, or Deep Space 2 (DS2), is the second of the New Millennium Program planetary missions and is designed to enable future space science network missions through flight validation of new technologies. A secondary goal is the collection of meaningful science data. Two micropenetrators will be deployed to carry out surface and subsurface science. The penetrators are being carried as a piggyback payload on the Mars Polar Lander cruise ring and will be launched in January 1999. The microprobe has no active control, attitude determination, or propulsive systems. It is a single stage from separation until landing and will passively orient itself due to its aerodynamic design. The aeroshell will be made of a nonerosive heat shield material, Silicon impregnated Reusable Ceramic Ablator(SIRCA), developed at Ames Research Center. The aeroshell shatters on impact, at which time the probe separates into an aftbody that remains at the surface and a forebody that penetrates into the subsurface. Each probe has a total mass of up to 3 kg, including the aeroshell. The impact velocity will be about 180 meters per second. The forebody will experience up to 30,000 g's and penetrate between 0.3 and 2 meters, depending on the ice content of the soil. The aftbody deceleration will be up to 80,000 g. The penetrators arrive in December 1999. The landing ellipse latitude range is 73 deg-77 deg S. The longitude will be selected by the Mars Surveyor Project to place the lander on the polar layered deposits in the range of 180 deg -230 deg W. The two micropenetrators are likely to land within 100 km of the Mars Surveyor Lander, on the polar deposits. The likely arrival date is L(sub s) = 256, late southern spring. The nominal mission lasts 2 days. A science team was selected in April 1998.

  20. Deep Space 2: The Mars Microprobe Project and Beyond

    NASA Astrophysics Data System (ADS)

    Smrekar, S. E.; Gavit, S. A.

    1998-01-01

    The Mars Microprobe Project, or Deep Space 2 (DS2), is the second of the New Millennium Program planetary missions and is designed to enable future space science network missions through flight validation of new technologies. A secondary goal is the collection of meaningful science data. Two micropenetrators will be deployed to carry out surface and subsurface science. The penetrators are being carried as a piggyback payload on the Mars Polar Lander cruise ring and will be launched in January 1999. The microprobe has no active control, attitude determination, or propulsive systems. It is a single stage from separation until landing and will passively orient itself due to its aerodynamic design. The aeroshell will be made of a nonerosive heat shield material, Silicon impregnated Reusable Ceramic Ablator(SIRCA), developed at Ames Research Center. The aeroshell shatters on impact, at which time the probe separates into an aftbody that remains at the surface and a forebody that penetrates into the subsurface. Each probe has a total mass of up to 3 kg, including the aeroshell. The impact velocity will be about 180 meters per second. The forebody will experience up to 30,000 g's and penetrate between 0.3 and 2 meters, depending on the ice content of the soil. The aftbody deceleration will be up to 80,000 g. The penetrators arrive in December 1999. The landing ellipse latitude range is 73 deg-77 deg S. The longitude will be selected by the Mars Surveyor Project to place the lander on the polar layered deposits in the range of 180 deg -230 deg W. The two micropenetrators are likely to land within 100 km of the Mars Surveyor Lander, on the polar deposits. The likely arrival date is Ls = 256, late southern spring. The nominal mission lasts 2 days. A science team was selected in April 1998.

  1. Proton pump inhibitors and vascular function: A prospective cross-over pilot study

    PubMed Central

    Ghebremariam, Yohannes T.; Cooke, John P.; Khan, Fouzia; Thakker, Rahul N.; Chang, Peter; Shah, Nigam H.; Nead, Kevin T.; Leeper, Nicholas J.

    2015-01-01

    Background Proton pump inhibitors (PPIs) are commonly used drugs for the treatment of gastric reflux. Recent retrospective cohorts and large database studies have raised concern that the use of PPIs is associated with increased cardiovascular (CV) risk. However, there is no prospective clinical study evaluating whether the use of PPIs directly causes CV harm. Methods We conducted a controlled open-label cross-over pilot study among 21 adults aged 18 and older who are healthy (n = 11) or have established clinical cardiovascular disease (n = 10). Study subjects were assigned to receive a PPI (Prevacid; 30 mg) or a placebo pill once daily for 4 weeks. After a 2 week washout period, participants were crossed-over to receive the alternate treatment for the ensuing 4 weeks. Subjects underwent evaluation of vascular function (by the EndoPAT technique) and had plasma levels of asymmetric dimethylarginine (ADMA, an endogenous inhibitor of endothelial function previously implicated in PPI-mediated risk) measured prior to and after each treatment interval. Results We observed a marginal inverse correlation between the EndoPAT score and plasma levels of ADMA (r = −0.364). Subjects experienced a greater worsening in plasma ADMA levels while on PPI than on placebo, and this trend was more pronounced amongst those subjects with a history of vascular disease. However, these trends did not reach statistical significance, and PPI use was also not associated with an impairment in flow mediated vasodilation during the course of this study. Conclusions In this open-label, cross-over pilot study conducted among healthy subjects and coronary disease patients, PPI use did not significantly influence vascular endothelial function. Larger, long-term and blinded trials are needed to mechanistically explain the correlation between PPI use and adverse clinical outcomes, which has recently been reported in retrospective cohort studies. PMID:25835348

  2. Conductivity and electrical studies of plasticized carboxymethyl cellulose based proton conducting solid biopolymer electrolytes

    NASA Astrophysics Data System (ADS)

    Isa, M. I. N.; Noor, N. A. M.

    2015-12-01

    In this paper, a proton conducting solid biopolymer electrolytes (SBE) comprises of carboxymethyl cellulose (CMC) as polymer host, ammonium thiocyanate (NH4SCN) as doping salt and ethylene carbonate (EC) as plasticizer has been prepared via solution casting technique. Electrical Impedance Spectroscopy (EIS) was carried out to study the conductivity and electrical properties of plasticized CMC-NH4SCN SBE system over a wide range of frequency between 50 Hz and 1 MHz at temperature range of 303 to 353 K. Upon addition of plasticizer into CMC-NH4SCN SBE system, the conductivity increased from 10-5 to 10-2 Scm-1. The highest conductivity was obtained by the electrolyte containing 10 wt.% of EC. The conductivity of plasticized CMC-NH4SCN SBE system by various temperatures obeyed Arrhenius law where the ionic conductivity increased as the temperature increased. The activation energy, Ea was found to decrease with enhancement of EC concentration. Dielectric studies for the highest conductivity electrolyte obeyed non-Debye behavior. The conduction mechanism for the highest conductivity electrolyte was determined by employing Jonsher's universal power law and thus, can be represented by the quantum mechanical tunneling (QMT) model.

  3. A study of the energy dependence of the underlying event in proton-antiproton collisions

    DOE PAGESBeta

    Aaltonen, T.

    2015-11-23

    We study charged particle production (pT > 0.5 GeV/c, |η| < 0.8) in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of η-Φspace; “toward”, “away”, and “transverse”. Furthermore, the average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the “underlying event”. The transverse region is divided into a MAX and MIN transverse region, which helps separate the “hard component” (initial and final-state radiation) from the “beam-beammore » remnant” and multiple parton interaction components of the scattering. We found that the center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.« less

  4. A study of the energy dependence of the underlying event in proton-antiproton collisions

    SciTech Connect

    Aaltonen, T.

    2015-11-23

    We study charged particle production (pT > 0.5 GeV/c, |η| < 0.8) in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of η-Φspace; “toward”, “away”, and “transverse”. Furthermore, the average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the “underlying event”. The transverse region is divided into a MAX and MIN transverse region, which helps separate the “hard component” (initial and final-state radiation) from the “beam-beam remnant” and multiple parton interaction components of the scattering. We found that the center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  5. Study of the energy dependence of the underlying event in proton-antiproton collisions

    SciTech Connect

    Nodulman, L.; Aaltonen, T; Albrow, M; Amerio, S.; Amidei, D; Anastassov, A.; Annovi, A; Antos, J; Apollinari, G.; Appel, J A; Arisawa, T

    2015-11-23

    We study charged particle production (p(T) > 0.5 GeV/c, vertical bar eta vertical bar < 0.8) in proton-antiproton collisions at total center-of-mass energies root s = 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta - phi space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  6. Are proton pump inhibitors a new antidiabetic drug? A cross sectional study

    PubMed Central

    Boj-Carceller, Diana; Bocos-Terraz, Pilar; Moreno-Vernis, Miguel; Sanz-Paris, Alejandro; Trincado-Aznar, Pablo; Albero-Gamboa, Ramón

    2011-01-01

    AIM: To investigate the effect of proton pump inhibitors (PPIs) on glycemic control (HbA1c) in type 2 diabetic patients. METHODS: A cross-sectional study of consecutive in-patients admitted to hospital in any department during the first semester of the year 2010 who had a recent HbA1c measurement. The study excluded those with a diagnosis of hyperglycemic decompensation, diabetic onset or pregnancy. It compared HbA1c levels of those taking PPIs and those not. RESULTS: A total of 97 patients were recruited. The average HbA1C level was 7.0% ± 1.2%. Overall PPI consumption was 55.7%. HbA1c was significantly lower in individuals who took PPIs: -0.6%, 95% CI: -0.12 to -0.83. People who used PPIs with some type of insulin therapy had a HbA1c reduction by -0.8%, 95% CI: -0.12 to -1.48. For the rest of subgroup analysis based on the antidiabetic drug used, PPI consumption always exhibited lower HbA1c levels. CONCLUSION: PPIs seems to be consistently associated with better glycemic control in type 2 diabetes. HbA1c reduction observed is similar to incretin-based therapies. PMID:22174957

  7. Study of the energy dependence of the underlying event in proton-antiproton collisions

    NASA Astrophysics Data System (ADS)

    Aaltonen, T.; Albrow, M.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Butti, P.; Buzatu, A.; Calamba, A.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Chokheli, D.; Clark, A.; Clarke, C.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Demortier, L.; Deninno, M.; D'Errico, M.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Ebina, K.; Edgar, R.; Elagin, A.; Erbacher, R.; Errede, S.; Esham, B.; Farrington, S.; Fernández Ramos, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.; Galloni, C.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, M.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hays, C.; Heinrich, J.; Herndon, M.; Hocker, A.; Hong, Z.; Hopkins, W.; Hou, S.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. H.; Kim, S. B.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kurata, M.; Laasanen, A. T.; Lammel, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lee, H. S.; Lee, J. S.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lipeles, E.; Lister, A.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lucá, A.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Marchese, L.; Margaroli, F.; Marino, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagliarone, C.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parker, W.; Pauletta, G.; Paulini, M.; Paus, C.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ristori, L.; Robson, A.; Rodriguez, T.; Rolli, S.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Song, H.; Sorin, V.; St. Denis, R.; Stancari, M.; Stentz, D.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Vázquez, F.; Velev, G.; Vellidis, C.; Vernieri, C.; Vidal, M.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wallny, R.; Wang, S. M.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wilbur, S.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Zanetti, A. M.; Zeng, Y.; Zhou, C.; Zucchelli, S.; CDF Collaboration

    2015-11-01

    We study charged particle production (pT>0.5 GeV /c , |η |<0.8 ) in proton-antiproton collisions at total center-of-mass energies √{s }=300 GeV , 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of η -ϕ space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  8. Isomer Studies for Nuclei near the Proton Drip Line in the Mass 130-160 Region

    SciTech Connect

    Cullen, D. M.; Mason, P. J. R.; Khan, S.; Kishada, A. M.; Varley, B. J.; Rigby, S. V.; Scholey, C.; Greenlees, P.; Rahkila, P.; Jones, P. M.; Julin, R.; Juutinen, S.; Leino, M.; Leppaenen, A. P.; Nyman, M.; Uusitalo, J.; Grahn, T.; Nieminen, P.; Pakarinen, J.

    2007-11-30

    This report details the status of an experimental research programme which has studied isomeric states in the mass 130-160 region of the nuclear chart. Several new isomers have been established and characterised near the proton drip line using a recoil isomer tagging technique at the University of Jyvaeskylae, Finland. The latest experiments have been performed with a modified setup where the standard GREAT focal-plane double-sided silicon-strip detector was changed to a dual multi-wire proportional-counter arrangement. This new setup has improved capability for short-lived isomer studies where high focal-plane rates can be tolerated. The results of key recent experiments for nuclei situated above ({sup 153}Yb,{sup 152}Tm) and below ({sup 136}Pm,{sup 142}Tb) the N = 82 shell gap were presented along with an interpretation for the isomers. Finally, the future prospects of the technique, using an isomer-tagged differential-plunger setup, were discussed. This technique will be capable of establishing the deformation of the states above the isomers and will aid in the process of assigning underlying single-particle configurations to the isomeric states.

  9. An analytical model and parametric study of electrical contact resistance in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Wu, Zhiliang; Wang, Shuxin; Zhang, Lianhong; Hu, S. Jack

    This paper presents an analytical model of the electrical contact resistance between the carbon paper gas diffusion layers (GDLs) and the graphite bipolar plates (BPPs) in a proton exchange membrane (PEM) fuel cell. The model is developed based on the classical statistical contact theory for a PEM fuel cell, using the same probability distributions of the GDL structure and BPP surface profile as previously described in Wu et al. [Z. Wu, Y. Zhou, G. Lin, S. Wang, S.J. Hu, J. Power Sources 182 (2008) 265-269] and Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Results show that estimates of the contact resistance compare favorably with experimental data by Zhou et al. [Y. Zhou, G. Lin, A.J. Shih, S.J. Hu, J. Power Sources 163 (2007) 777-783]. Factors affecting the contact behavior are systematically studied using the analytical model, including the material properties of the two contact bodies and factors arising from the manufacturing processes. The transverse Young's modulus of chopped carbon fibers in the GDL and the surface profile of the BPP are found to be significant to the contact resistance. The factor study also sheds light on the manufacturing requirements of carbon fiber GDLs for a better contact performance in PEM fuel cells.

  10. Molecular organization in the native state of woody tissue: Studies of tertiary structure and its development using the Raman microprobe, solid state {sup 13}C NMR, fluorescence spectroscopy and photoconductivity. Progress report, July 1, 1992--June 30, 1994

    SciTech Connect

    Atalla, R.H.

    1995-05-01

    The work completed in the current program period is reported in 14 publications, some of which have appeared in print, and the rest of which are either in review, or will be by the end of September; five are attached to this report. The reports are conveniently discussed in four categories. The first is concerned with studies of cellulose and of the manner in which the hemicelluloses can influence the aggregation of the cellulose. This the focus is the polysaccharide matrix and the couplings that occur between its components. The second category includes the molecular modeling studies. These are new in our program, and cover explorations of the dominant characteristics of the polysaccharides and the precursors of lignin. The third group of publications address our realization that the polysaccharide matrix may well be the key to understanding the source of organization in native lignins. The fourth set of publications deal with direct conservations of organization in native lignin and the characteristic properties which reflect this organization.

  11. Heavy ion microprobes: a unique tool for bystander research and other radiobiological applications

    NASA Astrophysics Data System (ADS)

    Voss, K. O.; Fournier, C.; Taucher-Scholz, G.

    2008-07-01

    The risk assessment for low doses of high linear energy transfer (LET) radiation has been challenged by a growing body of experimental evidence showing that non-irradiated bystander cells can receive signals from irradiated cells to elicit a variety of cellular responses. These may be significant for radiation protection but also for radiation therapy using heavy ions. Charged particle microbeams for radiobiological application provide a unique means to address these issues by allowing the precise irradiation of single cells with a counted numbers of ions. Here, we focus specifically on heavy ion microbeam facilities currently in use for biological purposes, describing their technical features and biological results. Typically, ion species up to argon are used for targeted biological irradiation at the vertically collimated microbeam at JAEA (Takasaki, Japan). At the SNAKE microprobe in Munich, mostly oxygen ions have been used in a horizontal focused beam line for cell targeting. At GSI (Darmstadt), a horizontal microprobe with a focused beam for defined targeting using ion species up to uranium is operational. The visualization of DNA damage response proteins relocalizing to defined sites of ion traversal has been accomplished at the three heavy ion microbeam facilities described above and is used to study mechanistic aspects of heavy ion effects. However, bystander studies have constituted the main focus of biological applications. While for cell inactivation and effects on cell cycle progression a response of non-targeted cells has been described at JAEA and GSI, respectively, in part controversial results have been obtained for the induction of DNA damage measured by double-strand formation or at the cytogenetic level. The results emphasize the influence of the cellular environment, and standardization of experimental conditions for cellular studies at different facilities as well as the investigation of bystander effects in tissue will be the aims of future

  12. Experimental study of meteorological parameters variation using hf-signal during solar proton events

    NASA Astrophysics Data System (ADS)

    Goncharenko, Yu.; Gutnik, V.; Kivva, F.

    Nowadays there are many experimental facts showing the Solar activity influence on a weather and climate. Nevertheless we still do not have a model explaining all the problems of Solar-terrestrial links. This lack is due to the deficit of the experimental data about variations of the meteorological conditions before, during and after a solar flare. This type of data could be obtained by use of weather balloon, rocket or aircraft sounding, etc. But all of these methods could not be used for achieving of large arrays of continuous data due to their large cost. Refractive index, which plays a significant role in radiowave propagation, relates to the main meteorological parameters such as temperature, pressure and vapor pressure [1]. So, statistical studies of the signal level variation processes can give some information about meteorological processes in troposphere. To solve this problem an experimental radio link from telecommunication satellite Asiasat-3S (elevation angle in Kharkov, Ukraine is 4.5o) was constructed. The experiment was carried out from May-2002 till November-2003 at the frequency 3.6GHz. More than 20 solar flare events were analyzed. It was found that during strong solar flare with proton flux index (p.f.u.) >200 a deep rapid fading appears. The fading rate of the signal increased in 10-15 times at the level -6dB and in 5-10 times at the level -4dB from the signal mean value in 3-6 hours after solar flare had begun. It is necessary to note that during solar flare with p.f.u <200 this effects are not registered. The duration of the signal fading increased, too. Two to three days later the behavior of the received signal returns to the normal, non-flare state. This fading can be connected to phenomena of the interference between few signals originating at different sources like tropospheric inhomogeneouses and the satellite. These inhomogeneouses are linked to small-scale fluctuation of refractive index. It is necessary to note that radio waves

  13. Proton pump inhibitor step-down therapy for GERD: A multi-center study in Japan

    PubMed Central

    Tsuzuki, Takao; Okada, Hiroyuki; Kawahara, Yoshiro; Takenaka, Ryuta; Nasu, Junichiro; Ishioka, Hidehiko; Fujiwara, Akiko; Yoshinaga, Fumiya; Yamamoto, Kazuhide

    2011-01-01

    AIM: To investigate the predictors of success in step-down of proton pump inhibitor and to assess the quality of life (QOL). METHODS: Patients who had heartburn twice a week or more were treated with 20 mg omeprazole (OPZ) once daily for 8 wk as an initial therapy (study 1). Patients whose heartburn decreased to once a week or less at the end of the initial therapy were enrolled in study 2 and treated with 10 mg OPZ as maintenance therapy for an additional 6 mo (study 2). QOL was investigated using the gastrointestinal symptom rating scale (GSRS) before initial therapy, after both 4 and 8 wk of initial therapy, and at 1, 2, 3, and 6 mo after starting maintenance therapy. RESULTS: In study 1, 108 patients were analyzed. Their characteristics were as follows; median age: 63 (range: 20-88) years, sex: 46 women and 62 men. The success rate of the initial therapy was 76%. In the patients with successful initial therapy, abdominal pain, indigestion and reflux GSRS scores were improved. In study 2, 83 patients were analyzed. Seventy of 83 patients completed the study 2 protocol. In the per-protocol analysis, 80% of 70 patients were successful for step-down. On multivariate analysis of baseline demographic data and clinical information, no previous treatment for gastroesophageal reflux disease (GERD) [odds ratio (OR) 0.255, 95% CI: 0.06-0.98] and a lower indigestion score in GSRS at the beginning of step-down therapy (OR 0.214, 95% CI: 0.06-0.73) were found to be the predictors of successful step-down therapy. The improved GSRS scores by initial therapy were maintained through the step-down therapy. CONCLUSION: OPZ was effective for most GERD patients. However, those who have had previous treatment for GERD and experience dyspepsia before step-down require particular monitoring for relapse. PMID:21472108

  14. SU-E-T-590: An Activation Study of Materials and Devices Present in a Proton Treatment Room

    SciTech Connect

    Spitznagel, D

    2014-06-01

    Purpose: The use of protons for radiation therapy is growing rapidly. One consequence of protons interacting with different media is activation. These nuclear reactions induced by the protons, scattered neutrons, and gamma rays, activate different materials encountered, particularly by the therapists. The purpose of this study was to examine the derived nuclides from the activation, and also the decay rate. Methods: The study was conducted in our proton therapy facility. Protons are derived from a synchrocyclotron and pass through field shipping systems, apertures, and range compensators to define the beam within the patient.Included materials of concerns measured; the patient support couch, sheet rock in the wall, solid plastics used for quality assurance and dosimetry, and the passive scattering system itself, which includes brass apertures, and Lucite or blue wax compensators. All devices were studied post irradiation using gamma spectroscopy to determine the nuclides, and a sodium iodine scintillation detector to measure decay, particularly when the dose rate fell to background levels. Results: We have also determined from the measurements we will maintain brass apertures for three months before sending them for scrap. Some of the radionuclides arrived from these measurements included Na-22 for the blue wax compensator, C1-34m for the sheetrock, and Sc-44 and Co-60 for the brass apertures. We found compensators made out of Lucite or wax decayed to background in 2 hours. The patient support couch decayed to background in approximately 40 minutes, and sheet rock decayed in 80 minutes. In terms of the aperture layers, the most proximal aperture slab had much higher activity than the distal slab. Also the proximal sides of the slabs were much more activate than the distal. Conclusion: We have given proper instruction to therapists performing quality assurance in terms of the handled plastics, and to handle apertures rapidly as possible.

  15. DFT study of sulfur derivatives of cumulenes and their protonated forms of interstellar interest and calculations of dissociation energies of protonated forms (SC(CH)C(n-2)S)(+) (n = 3-8).

    PubMed

    Benmensour, Mohamed Ali; Djennane-Bousmaha, Sema; Boucekkine, Abdou

    2014-07-01

    A theoretical study of the sulfur cumulenes SCnS (n = 3-8), CnS ( n = 1-8) and of their protonated forms (SCnS)H(+) and (CnS)H(+) that might exist in the interstellar environment, has been carried out by means of the standard B3LYP/6-311G** method. The geometries and relative energies of singlet and triplet states according to the number of carbons have been computed. Like neutral species, we have found that the ground state of the most stable protonated forms (SC(CH)Cn-2S)(+) and ((HC)Cn-1S)(+), alternates between a triplet state for the even series and a singlet state for the odd series. We provided the data needed to simulate infrared and microwave spectra (vibration frequencies, dipole moments, and rotational constants) for each protonated species (SCnS)H(+) and (CnS)H(+) and for each neutral CnS species. The computing of dissociation energies of the most stable protonated forms (SC(CH)Cn-2S)(+) (n = 3-8) has shown that the lowest values are obtained for the dissociation of compounds with an even number of carbons, in their triplet state, which produce the observed fragments CS and C3S. The dissociation of even protonated forms requires less energy than for the odd protonated forms. PMID:24935110

  16. In-beam PET imaging for on-line adaptive proton therapy: an initial phantom study

    NASA Astrophysics Data System (ADS)

    Shao, Yiping; Sun, Xishan; Lou, Kai; Zhu, Xiaorong R.; Mirkovic, Dragon; Poenisch, Falk; Grosshans, David

    2014-07-01

    We developed and investigated a positron emission tomography (PET) system for use with on-line (both in-beam and intra-fraction) image-guided adaptive proton therapy applications. The PET has dual rotating depth-of-interaction measurable detector panels by using solid-state photomultiplier (SSPM) arrays and LYSO scintillators. It has a 44 mm diameter trans-axial and 30 mm axial field-of-view (FOV). A 38 mm diameter polymethyl methacrylate phantom was placed inside the FOV. Both PET and phantom axes were aligned with a collimated 179.2 MeV beam. Each beam delivered ˜50 spills (0.5 s spill and 1.5 s inter-spill time, 3.8 Gy at Bragg peak). Data from each beam were acquired with detectors at a given angle. Nine datasets for nine beams with detectors at nine different angles over 180° were acquired for full-tomographic imaging. Each dataset included data both during and 5 min after irradiations. The positron activity-range was measured from the PET image reconstructed from all nine datasets and compared to the results from simulated images. A 22Na disc-source was also imaged after each beam to monitor the PET system's performance. PET performed well except for slight shifts of energy photo-peak positions (<1%) after each beam, due mainly to the neutron exposure of SSPM that increased the dark-count noise. This minor effect was corrected offline with a shifting 350-650 keV energy window for each dataset. The results show a fast converging of activity-ranges measured by the prototype PET with high sensitivity and uniform resolution. Sub-mm activity-ranges were achieved with minimal 6 s acquisition time and three spill irradiations. These results indicate the feasibility of PET for intra-fraction beam-range verification. Further studies are needed to develop and apply a novel clinical PET system for on-line image-guided adaptive proton therapy.

  17. Two-pulse NMR techniques for studying proton-unpaired electron interactions in coals and chars

    NASA Astrophysics Data System (ADS)

    Barton, W. A.; Lynch, L. J.

    The time-domain NMR signals stimulated in solids by two-pulse sequences of the form 90°- τ- βφ, where β is the angle of rotation and φ the relative phase of the second pulse which is separated from the initial 90° pulse by a time τ, can be influenced by the presence of a second spin species and therefore, in principle, can yield information on the separate contributions, M2II and M2IS, of like- and unlike-spin interactions to the Van Vleck second moment M2I of the resonant spins. The validity of the standard operator formalism for predicting the transverse magnetization signals thus produced in homogeneous solids by the 90°- τ-90 φ° and 90°- τ-180 φ° ( φ = 0° and 90°) sequences is discussed and the effects of pulse duration are briefly outlined. The time-series expansions yielded by the operator formalism for these signals are reviewed with emphasis on the effects of unlike-spin interactions, and a useful difference signal is discussed. The potential for application of these two-pulse techniques to protons in heterogeneous solids such as coals, in which unpaired electrons constitute the second spin species, is considered and experimentally assessed. Semiquantitative estimates of M2IS are made for protons in diphenyl picryl hydrazyl (DPPH) and several coals and chars at room temperature from measurements of the amplitude of the 90°- τ-90° 0 ° transient signal at small τ and of the initial rate of attenuation of the 90°- τ-90 90°° solid echo with increasing τ. It is found that (i) organic radicals and paramagnetic ions produce relatively small M2IS values, a result which limits the usefulness of this approach to studying unpaired electron properties of coals and chars; (ii) the M2II values deduced from these results and calculations of M2I follow expected trends; and (iii) only specimens containing small particles of magnetically ordered material give rise to rapidly decaying time-domain signals and a well-defined 90°- τ-180 90°° spin

  18. Microprobe Evaluations of Grain Boundary Segregation in KM4 and IN100

    NASA Technical Reports Server (NTRS)

    Gabb, T. P.; Smith, J. W.

    2001-01-01

    Turbine disk alloys subjected to fatigue cycles with dwells at high temperatures and stresses can fail by cracking along grain boundaries. This could be due to concentrated creep deformation or environmental attack at grain boundaries. It would be important to identify any chemical segregation along grain boundaries to aid understanding of this intergranular failure mode. The objective of this study was to evaluate the degree of chemical segregation present at the grain boundaries of two disk alloys, KM4 and IN 100. An electron microprobe employing wavelength dispersive x-ray chemical analyses was used to characterize the chemistry along multiple grain boundaries in metallographically prepared samples of each alloy. Some degrees of boron, chromium, and cobalt enrichment of grain boundaries were observed in each alloy.

  19. Garnet/high-silica rhyolite trace element partition coefficients measured by ion microprobe

    USGS Publications Warehouse

    Sisson, T.W.; Bacon, C.R.

    1992-01-01

    Garnet/liquid trace element partition coefficients have been measured in situ by ion microprobe in a rhyolite from Monache Mountain, California. Partition coefficients are reported for La, Ce, Nd, Sm, Dy, Er, Yb, Sc, Ti, V, Cr, Sr, Y, and Zr. The in situ analyses avoid the problem of contamination of the garnet phase by trace element-rich accessory minerals encountered in traditional bulk phenocryst/matrix partitioning studies. The partitioning pattern for the rare earth elements (REEs, excluding Eu) is smooth and rises steeply from the light to the heavy REEs with no sharp kinks or changes in slope, unlike patterns for garnet /silicic liquid REE partitioning determined by bulk methods. This difference suggests that the previous determinations by bulk methods are in error, having suffered from contamination of the phenocryst separates. ?? 1992.

  20. Transparent intracortical microprobe array for simultaneous spatiotemporal optical stimulation and multichannel electrical recording.

    PubMed

    Lee, Joonhee; Ozden, Ilker; Song, Yoon-Kyu; Nurmikko, Arto V

    2015-12-01

    Optogenetics, the selective excitation or inhibition of neural circuits by light, has become a transformative approach for dissecting functional brain microcircuits, particularly in in vivo rodent models, owing to the expanding libraries of opsins and promoters. Yet there is a lack of versatile devices that can deliver spatiotemporally patterned light while performing simultaneous sensing to map the dynamics of perturbed neural populations at the network level. We have created optoelectronic actuator and sensor microarrays that can be used as monolithic intracortical implants, fabricated from an optically transparent, electrically highly conducting semiconductor ZnO crystal. The devices can perform simultaneous light delivery and electrical readout in precise spatial registry across the microprobe array. We applied the device technology in transgenic mice to study light-perturbed cortical microcircuit dynamics and their effects on behavior. The functionality of this device can be further expanded to optical imaging and patterned electrical microstimulation. PMID:26457862

  1. PET - A proton/electron telescope for studies of magnetospheric, solar, and galactic particles

    NASA Technical Reports Server (NTRS)

    Cook, Walter R.; Cummings, Alan C.; Cummings, Jay R.; Garrard, Thomas L.; Kecman, Branislav; Mewaldt, Richard A.; Selesnick, Richard S.; Stone, Edward C.; Baker, Daniel N.; Von Rosenvinge, Tycho T.

    1993-01-01

    The Proton/Electron Telescope (PET) on SAMPEX is designed to provide measurements of energetic electrons and light nuclei from solar, galactic, and magnetospheric sources. PET is an all solid-state system that will measure the differential energy spectra of electrons from about 1 to about 30 MeV and H and He nuclei from about 20 to about 300 MeV/nuc, with isotope resolution of H and He extending from about 20 to about 80 MeV/nuc. As SAMPEX scans all local times and geomagnetic cutoffs over the course of its near-polar orbit, PET will characterize precipitating relativistic electron events during periods of declining solar activity, and it will examine whether the production rate of odd nitrogen and hydrogen molecules in the middle atmosphere by precipitating electrons is sufficient to affect O3 depletion. In addition, PET will complement studies of the elemental and isotopic composition of energetic heavy (Z greater than 2) nuclei on SAMPEX by providing measurements of H, He, and electrons. Finally, PET has limited capability to identify energetic positrons from potential natural and man-made sources.

  2. Helical stacking in DNA three-way junctions containing two unpaired pyrimidines: proton NMR studies.

    PubMed Central

    Leontis, N B; Hills, M T; Piotto, M; Ouporov, I V; Malhotra, A; Gorenstein, D G

    1995-01-01

    The proton NMR spectra of DNA three-way junction complexes (TWJ) having unpaired pyrimidines, 5'-TT- and 5'-TC- on one strand at the junction site were assigned from 2D NOESY spectra acquired in H2O and D2O solvents and homonuclear 3D NOESY-TOCSY and 3D NOESY-NOESY in D2O solvent. TWJ are the simplest branched structures found in biologically active nucleic acids. Unpaired nucleotides are common features of such structures and have been shown to stabilize junction formation. The NMR data confirm that the component oligonucleotides assemble to form conformationally homogeneous TWJ complexes having three double-helical, B-form arms. Two of the helical arms stack upon each other. The unpaired pyrimidine bases lie in the minor groove of one of the helices and are partly exposed to solvent. The coaxial stacking arrangement deduced is different from that determined by Rosen and Patel (Rosen, M.A., and D.J. Patel. 1993. Biochemistry. 32:6576-6587) for a DNA three-way junction having two unpaired cytosines, but identical to that suggested by Welch et al. (Welch, J. B., D. R. Duckett, D. M. J. Lilley. 1993. Nucleic Acids Res. 21:4548-4555) on the basis of gel electrophoretic studies of DNA three-way junctions containing unpaired adenosines and thymidines. Images FIGURE 2 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 PMID:7711249

  3. Proton magnetic resonance studies of 2'-,3'-, and 5'-deoxyadenosine conformations in solution.

    PubMed Central

    Westhof, E; Plach, H; Cuno, I; Lüdemann, H D

    1977-01-01

    Proton magnetic resonance studies of 2'-deoxyadenosine (2'-dA), 3'-deoxyadenosine (3'-dA), 5'-deoxyadenosine (5'-dA) and 8-bromo-5'-deoxyadenosine (8-Br-5'-dA) have been carried out in the temperature range between -60 degrees and +40 degrees C for ND3 solutios, +40 degrees and +100 degrees C for D2O solutions, and finally +10 degrees and +60 degrees C for pyridine solutions. The analysis is based on the two-state S in equilibrium N model of the ribose moiety proposed by Altona and Sundaralingam. In all solvents, 2'-dA favours slightly the S state of the ribose and the g+ conformer of the exocyclic CH2OH group. However, 3'-dA prefers strongly the N state of the ribose and the g+ conformation. Both the S and N states of the ribose are equally favoured by 5'-DA and 8-Br-5'-dA. Evidence for the existence of an intramolecular hydrogen bond between 0(5') and N3 in purine (beta)-nucleosides is presented. It is also concluded that cordycepin (3'-dA) exists in solution mainly in the anti conformation of the base relative to the ribose. PMID:301272

  4. EGRET High Energy Capability and Multiwavelength Flare Studies and Solar Flare Proton Spectra

    NASA Technical Reports Server (NTRS)

    Chupp, Edward L.

    1998-01-01

    The accomplishments of the participation in the Compton Gamma Ray Observatory Guest investigator program is summarized in this report. The work involved the study of Energetic Gamma Ray Experiment Telescope (EGRET)/Total Absorption Shower Counter(TASC) flare data. The specific accomplishments were the use of the accelerator neutron measurements obtained at the University of New Hampshire to verify the TASC response function and to modify the TASC fitting program to include a high energy neutron contribution, and to determine a high energy neutron contribution to the emissions from the 1991 June 11, solar flare. The next step in the analysis of this event was doing fits to the TASC energy-loss spectra as a function of time. A significant hardening of the solar proton spectrum over time was found for the flare. Further data was obtained from the Yohkoh HXT time histories and images for the 1991 October 27 flare. The results to date demonstrate that the TASC spectral analysis contributes crucial information on the particle spectrum interacting at the Sun. The report includes a paper accepted for publication, a draft of a paper to be delivered at the 26th International Cosmic Ray Conference and an abstract of a paper to be presented at the Meeting of the American Physical Society.

  5. Proton-Proton Scattering at 105 Mev and 75 Mev

    DOE R&D Accomplishments Database

    Birge, R. W.; Kruse, U. E.; Ramsey, N. F.

    1951-01-31

    The scattering of protons by protons provides an important method for studying the nature of nuclear forces. Recent proton-proton scattering experiments at energies as high as thirty Mev{sup 1} have failed to show any appreciable contribution to the cross section from higher angular momentum states, but it is necessary to bring in tensor forces to explain the magnitude of the observed cross section.

  6. Radiograaff, a proton irradiation facility for radiobiological studies at a 4 MV Van de Graaff accelerator

    NASA Astrophysics Data System (ADS)

    Constanzo, J.; Fallavier, M.; Alphonse, G.; Bernard, C.; Battiston-Montagne, P.; Rodriguez-Lafrasse, C.; Dauvergne, D.; Beuve, M.

    2014-09-01

    A horizontal beam facility for radiobiological experiments with low-energy protons has been set up at the 4 MV Van de Graaff accelerator of the Institut de Physique Nucléaire de Lyon. A homogeneous irradiation field with a suitable proton flux is obtained by means of two collimators and two Au-scattering foils. A monitoring chamber contains a movable Faraday cup, a movable quartz beam viewer for controlling the intensity and the position of the initial incident beam and four scintillating fibers for beam monitoring during the irradiation of the cell samples. The beam line is ended by a thin aluminized Mylar window (12 μm thick) for the beam extraction in air. The set-up was simulated by the GATE v6.1 Monte-Carlo platform. The measurement of the proton energy distribution, the evaluation of the fluence-homogeneity over the sample and the calibration of the monitoring system were performed using a silicon PIPS detector, placed in air in the same position as the biological samples to be irradiated. The irradiation proton fluence was found to be homogeneous to within ±2% over a circular field of 20 mm diameter. As preliminary biological experiment, two Human Head and Neck Squamous Carcinoma Cell lines (with different radiosensitivities) were irradiated with 2.9 MeV protons. The measured survival curves are compared to those obtained after X-ray irradiation, giving a Relative Biological Efficiency between 1.3 and 1.4.

  7. SU-E-T-519: Emission of Secondary Particles From a PMMA Phantom During Proton Irradiation: A Simulation Study with the Geant4 Monte Carlo Toolkit

    SciTech Connect

    Lau, A; Chen, Y; Ahmad, S

    2014-06-01

    Purpose: Proton therapy exhibits several advantages over photon therapy due to depth-dose distributions from proton interactions within the target material. However, uncertainties associated with protons beam range in the patient limit the advantage of proton therapy applications. To quantify beam range, positron-emitting nuclei (PEN) and prompt gamma (PG) techniques have been developed. These techniques use de-excitation photons to describe the location of the beam in the patient. To develop a detector system for implementing the PG technique for range verification applications in proton therapy, we studied the yields, energy and angular distributions of the secondary particles emitted from a PMMA phantom. Methods: Proton pencil beams of various energies incident onto a PMMA phantom with dimensions of 5 x 5 x 50 cm3 were used for simulation with the Geant4 toolkit using the standard electromagnetic packages as well as the packages based on the binary-cascade nuclear model. The emitted secondary particles are analyzed . Results: For 160 MeV incident protons, the yields of secondary neutrons and photons per 100 incident protons were ~6 and ~15 respectively. Secondary photon energy spectrum showed several energy peaks in the range between 0 and 10 MeV. The energy peaks located between 4 and 6 MeV were attributed to originate from direct proton interactions with 12C (~ 4.4 MeV) and 16O (~ 6 MeV), respectively. Most of the escaping secondary neutrons were found to have energies between 10 and 100 MeV. Isotropic emissions were found for lower energy neutrons (<10 MeV) and photons for all energies, while higher energy neutrons were emitted predominantly in the forward direction. The yields of emitted photons and neutrons increased with the increase of incident proton energies. Conclusions: A detector system is currently being developed incorporating the yields, energy and angular distributions of secondary particles from proton interactions obtained from this study.

  8. Beam Loss Studies for the 2-MW LBNE Proton Beam Line

    SciTech Connect

    Drozhdin, A.I.; Childress, S.R.; Mokhov, N.V.; Tropin, I.S.; Zwaska, R.; /Fermilab

    2012-05-01

    Severe limits are put on allowable beam loss during extraction and transport of a 2.3 MW primary proton beam for the Long Baseline Neutrino Experiment (LBNE) at Fermilab. Detailed simulations with the STRUCT and MARS codes have evaluated the impact of beam loss of 1.6 x 10{sup 14} protons per pulse at 120 GeV, ranging from a single pulse full loss to sustained small fractional loss. It is shown that loss of a single beam pulse at 2.3 MW will result in a catastrophic event: beam pipe destruction, damaged magnets and very high levels of residual radiation inside and outside the tunnel. Acceptable beam loss limits have been determined and robust solutions developed to enable efficient proton beam operation under these constraints.

  9. Recoil Decay Tagging Study Of Transitional Proton Emitters 145,146,147Tm

    SciTech Connect

    Robinson, A.P.; Woods, P.J.; Davinson, T.; Liu, Z.; Davids, C.N.; Seweryniak, D.; Carpenter, M.P.; Hammond, N.; Janssens, R.V.F.; Mukherjee, G.; Sinha, S.; Blank, B.; Freeman, S.J.; Hoteling, N.; Shergur, J.; Walters, W.B.; Scholey, C.; Sonzogni, A.A.; Woehr, A.

    2005-04-05

    Gamma rays from the transitional proton emitting nuclei 145,146,147Tm have been observed using the recoil-decay tagging technique. The ground state band of 147Tm was confirmed and extended and the unfavoured signature sequence was observed. A ground state rotational band with properties of a decoupled h11/2 band was observed in 145Tm. In addition coincidences between the proton fine structure line and the 2+{yields}0+ {gamma}-ray transition in 144Er were detected at the focal plane of the FMA. This is the first time that coincidences between proton radioactive decays and {gamma} rays have been seen. The particle decay of 146Tm has been measured with improved statistics and a rotational band similar to 147Tm has been observed.

  10. Surface Structure of Protonated R-Sapphire (1$\\bar{1}$02) Studied by Sum-Frequency Vibrational Spectroscopy

    SciTech Connect

    Sung, Jaeho; Zhang, Luning; Tian, Chuanshan; Waychunas, Glenn A.; Shen, Y. Ron

    2011-03-23

    Sum frequency vibrational spectroscopy was used to study the protonated R-plane (1$\\bar{1}$02 ) sapphire surface. The OH stretch vibrational spectra show that the surface is terminated with three hydroxyl moieties, two from AlOH2 and one from Al2OH functional groups. The observed polarization dependence allows determination of the orientations of the three OH species. The results suggest that the protonated sapphire (1$\\bar{1}$02 ) surface differs from an ideal stoichimetric termination in a manner consistent with previous X-ray surface diffraction (crystal truncation rod) studies. However, in order to best explain the observed hydrogenbonding arrangement, surface oxygen spacing determined from the X-ray diffraction study requires modification.

  11. An X-Ray Microprobe for In-Situ Stone and Wood Characterization

    NASA Astrophysics Data System (ADS)

    Lovoi, P.; Asmus, J. F.

    NonDestructive Testing (NDT) has become an essential ingredient in the conservation of artworks and in the preservation of historic buildings. In many instances it is necessary to characterize the underlying strata of an artistic or historic object in order to plan technical conservation measures, to understand its history, to authenticate it, or to search for hidden features. X-ray and gamma-ray radiography as well as infrared imaging have been ubiquitous in conservation practice for generations. Recent decades have also seen the introduction of ultrasonic imaging, thermovision, x-ray fluorescence, neutron activation analyses, holographic interferometry, isotopic and trace element analyses, the electron microprobe, the laser microprobe, microwave impulse radar, eddy current imaging, and fiber-optic imaging. Unfortunately, for mainstream conservation and preservation some of these technologies are too costly or difficult to be implemented in any general way. In other instances penetration is too superficial or signals from the depth of interest are masked by interferences. Nevertheless, sufficiently important problems have arisen to warrant the utilization of each of the above NDT technologies as well as still others. A new diagnostic device has been introduced into the conservation field. Stone characterization analyses are reported using miniature x-ray devices that can be inserted into cracks and holes in specimens of interest. The family of x-ray tubes employed in these studies range in diameter from 1 to 6 mm. Operating voltages up to 50 kV are available. Electrical power and cooling are delivered through a flexible cable that has a bend diameter of less than 3 cm. Thus, it was possible to insert the x-ray tube into small holes and cracks in marble stones. In this manner radiographs of the outer strata of stones (and embedded metal pins) have been produced without having to transmit through the entire thickness of large blocks. It should also be possible to

  12. Nuclear microprobe analysis and source apportionment of individual atmospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Rabello, Marta L. C.; Watt, Frank; Grime, Geoff; Swietlicki, Erik

    1993-04-01

    In atmospheric aerosol research, one key issue is to determine the sources of the airborne particles. Bulk PIXE analysis coupled with receptor modeling provides a useful, but limited view of the aerosol sources influencing one particular site or sample. The scanning nuclear microprobe (SNM) technique is a microanalytical technique that gives unique information on individual aerosol particles. In the SNM analyses a 1.0 μm size 2.4 MeV proton beam from the Oxford SNM was used. The trace elements with Z > 11 were measured by the particle induced X-ray emission (PIXE) method with detection limits in the 1-10 ppm range. Carbon, nitrogen and oxygen are measured simultaneously using Rutherford backscattering spectrometry (RBS). Atmospheric aerosol particles were collected at the Brazilian Antarctic Station and at biomass burning sites in the Amazon basin tropical rain forest in Brazil. In the Antarctic samples, the sea-salt aerosol particles were clearly predominating, with NaCl and CaSO 4 as major compounds with several trace elements as Al, Si, P, K, Mn, Fe, Ni, Cu, Zn, Br, Sr, and Pb. Factor analysis of the elemental data showed the presence of four components: 1) soil dust particles; 2) NaCl particles; 3) CaSO 4 with Sr; and 4) Br and Mg. Strontium, observed at 20-100 ppm levels, was always present in the CaSO 4 particles. The hierarchical cluster procedure gave results similar to the ones obtained through factor analysis. For the tropical rain forest biomass burning aerosol emissions, biogenic particles with a high organic content dominate the particle population, while K, P, Ca, Mg, Zn, and Si are the dominant elements. Zinc at 10-200 ppm is present in biogenic particles rich in P and K. The quantitative aspects and excellent detection limits make SNM analysis of individual aerosol particles a very powerful analytical tool.

  13. Proton pump inhibitors and risk of periampullary cancers--A nested case-control study.

    PubMed

    Chien, Li-Nien; Huang, Yan-Jiun; Shao, Yu-Hsuan Joni; Chang, Chen-Jung; Chuang, Ming-Tsang; Chiou, Hung-Yi; Yen, Yun

    2016-03-15

    Considerable attention has been focused on long-term use of proton pump inhibitor (PPI) medications in relation to increased risk of cancer via stimulation of DNA-damaged cells. The aim of this study is to examine the dose-dependent effect of PPI on periampullary cancers in a national population-based cohort. A nested case-control analysis was constructed based on Taiwan's National Health Insurance Research Database and the Taiwan Cancer Registry between the years 2000 and 2010. Cases involving patients diagnosed with periampullary cancers were selected and controls were matched to cases according to age, sex and observational period. A "PPI user" was defined as any patient receiving more than 28 cumulative defined daily doses as measured by prescription drug claims. Conditional logistic regression analysis was conducted to calculate odds ratios (ORs) and 95% confidence intervals (CIs) according to the level of PPI exposure. A total of 7,681 cases and 76,762 matched controls were included with a mean follow-up period of 6.6 years (SD: 2.0). The odds of PPI exposure in patients with periampullary cancers were higher than that of control patients with an adjusted OR of 1.35 (95% CIs: 1.16-1.57). Our results also showed that PPI exposure was slightly linked to periampullary cancers in dose-dependent manner. A similar association was observed in patients who solely took PPI but no eradication therapy for Helicobacter pylori infection. Long-term PPI use was associated with an increased risk of periampullary cancers in the current population-based study. Physicians must weigh potential risks of long-term maintenance against therapeutic benefit. PMID:26488896

  14. Proton pump inhibitors and risk of periampullary cancers—A nested case–control study

    PubMed Central

    Chien, Li‐Nien; Huang, Yan‐Jiun; Shao, Yu‐Hsuan Joni; Chang, Chen‐Jung; Chuang, Ming‐Tsang; Chiou, Hung‐Yi

    2015-01-01

    Considerable attention has been focused on long‐term use of proton pump inhibitor (PPI) medications in relation to increased risk of cancer via stimulation of DNA‐damaged cells. The aim of this study is to examine the dose‐dependent effect of PPI on periampullary cancers in a national population‐based cohort. A nested case–control analysis was constructed based on Taiwan's National Health Insurance Research Database and the Taiwan Cancer Registry between the years 2000 and 2010. Cases involving patients diagnosed with periampullary cancers were selected and controls were matched to cases according to age, sex and observational period. A “PPI user” was defined as any patient receiving more than 28 cumulative defined daily doses as measured by prescription drug claims. Conditional logistic regression analysis was conducted to calculate odds ratios (ORs) and 95% confidence intervals (CIs) according to the level of PPI exposure. A total of 7,681 cases and 76,762 matched controls were included with a mean follow‐up period of 6.6 years (SD: 2.0). The odds of PPI exposure in patients with periampullary cancers were higher than that of control patients with an adjusted OR of 1.35 (95% CIs: 1.16–1.57). Our results also showed that PPI exposure was slightly linked to periampullary cancers in dose‐dependent manner. A similar association was observed in patients who solely took PPI but no eradication therapy for Helicobacter pylori infection. Long‐term PPI use was associated with an increased risk of periampullary cancers in the current population‐based study. Physicians must weigh potential risks of long‐term maintenance against therapeutic benefit. PMID:26488896

  15. Three new defined proton affinities for polybasic molecules in the gas-phase: Proton microaffinity, proton macroaffinity and proton overallaffinity

    NASA Astrophysics Data System (ADS)

    Salehzadeh, Sadegh; Bayat, Mehdi

    2006-08-01

    A theoretical study on complete protonation of a series of tetrabasic molecules with general formula N[(CH 2) nNH 2][(CH 2) mNH 2][(CH 2) pNH 2] (tren, pee, ppe, tpt, epb and ppb) is reported. For first time, three kinds of gas-phase proton affinities for each polybasic molecule are defined as: 'proton microaffinity (PA n, i)', 'proton macroaffinity (PA)' and 'proton overall affinity ( PA)'. The variations of calculated logPA in the series of these molecules is very similar to that of their measured log Kn. There is also a good correlation between the calculated gas-phase proton macroaffinities and proton overallaffinities with corresponding equilibrium macroconstants and overall protonation constants in solution.

  16. 6-D weak-strong beam-beam simulation study of proton lifetime in presence of head-on beam-beam compensation in the RHIC

    SciTech Connect

    Luo, Y.; Fischer, W.

    2010-08-01

    In this note we summarize the calculated particle loss of a proton bunch in the presence of head-on beam-beam compensation in the Relativistic Heavy Ion Collider (RHIC). To compensate the head-on beam-beam effect in the RHIC 250 GeV polarized proton run, we are introducing a DC electron beam with the same transverse profile as the proton beam to collide with the proton beam. Such a device is called an electron lens (e-lens). In this note we first present the optics and beam parameters and the tracking setup. Then we calculate and compare the particle loss of a proton bunch with head-on beam-beam compensation, phase advance of k{pi} between IP8 and the center of the e-lens and second order chromaticity correction. We scanned the proton beam's linear chromaticity, working point and bunch intensity. We also scanned the electron beam's intensity, transverse beam size. The effect of the electron-proton transverse offset in the e-lens was studied. In the study 6-D weak-strong beam-beam interaction model a la Hirata is used for proton collisions at IP6 and IP8. The e-lens is modeled as 8 slices. Each slice is modeled with as drift - (4D beam-beam kick) - drift.

  17. A carbon-13 and proton nuclear magnetic resonance study of some experimental referee broadened-specification /ERBS/ turbine fuels

    NASA Technical Reports Server (NTRS)

    Dalling, D. K.; Pugmire, R. J.

    1982-01-01

    Preliminary results of a nuclear magnetic resonance (NMR) spectroscopy study of alternative jet fuels are presented. A referee broadened-specification (ERBS) aviation turbine fuel, a mixture of 65 percent traditional kerosene with 35 percent hydrotreated catalytic gas oil (HCGO) containing 12.8 percent hydrogen, and fuels of lower hydrogen content created by blending the latter with a mixture of HCGO and xylene bottoms were studied. The various samples were examined by carbon-13 and proton NMR at high field strength, and the resulting spectra are shown. In the proton spectrum of the 12.8 percent hydrogen fuel, no prominent single species is seen while for the blending stock, many individual lines are apparent. The ERBS fuels were fractionated by high-performance liquid chromatography and the resulting fractions analyzed by NMR. The species found are identified.

  18. Laser Microprobe (U-Th)/He Thermochronology of Detrital Minerals

    NASA Astrophysics Data System (ADS)

    Hodges, K. V.; van Soest, M. C.

    2007-12-01

    A persistent concern in detrital mineral geochronology is the need to obtain a representative sampling of crystallization or cooling ages in the source region. Methods with high throughput --- e.g., laser microprobe 40Ar/39Ar thermochronology of muscovite and U-Pb thermochronology of zircon --- have a distinct advantage in this regard. Both techniques have advanced to the point that the dozens of analyses necessary to obtain a representative sampling can be done quickly and with sufficiently precision for high-quality research. Datasets obtained using methods that are far more labor intensive --- e.g., single-grain (U-Th)/He and fission track dating of minerals such as zircon --- typically include many fewer analyses. Consequently, we have less confidence that the cooling age distribution in the dataset represents the cooling age distribution in the source region. Of greater concern are analytical protocols that increase the probability of non-representative sampling. One example is the practice of picking zircon grains that are inclusion-free and euhedral (or nearly so) for conventional (U-Th)/He dating. While this practice is essential for successful conventional (U-Th)/He dating, it unavoidably leads to the systematic exclusion of grains that actually may represent significant portions of the source terrain. We describe a new approach to detrital mineral (U-Th)/He thermochronology that, in principle, provides a higher- fidelity record of the source region cooling history than the conventional technique. It involves the use of an excimer laser microprobe to ablate portions of the grain interiors from detrital zircons in a polished grain mount. (Prior to analyses, the grains can be mapped using backscattered electron and cathodoluminesence imagery.) The amounts of evolved 4He are typically so small that they are best measured using a magnetic-sector mass spectrometer rather than a quadrupole mass spectrometer of the type typically used for conventional (U- Th

  19. A Study of Spacecraft Charging Due to Exposure to Interplanetary Protons

    NASA Technical Reports Server (NTRS)

    Green, Nelson W.; Frederickson, A. Robb

    2006-01-01

    Long life spacecraft may be exposed to one or more major solar storms during the mission lifespan. This research task was undertaken to determine the risk to long duration interplanetary spacecraft from spacecraft charging due to exposure to solar energetic protons.

  20. Equation of state studies of warm dense matter samples heated by laser produced proton beams

    NASA Astrophysics Data System (ADS)

    Hoarty, D. J.; Guymer, T.; James, S. F.; Gumbrell, E.; Brown, C. R. D.; Hill, M.; Morton, J.; Doyle, H.

    2012-03-01

    Heating of matter by proton beams produced by short pulse, laser-solid target interaction has been demonstrated over the last ten years by a number of workers. In the work described in this paper heating by a pulse of laser produced protons has been combined with high-resolution soft x-ray radiography to record the expansion of thin wire targets. Analysis of the radiographs yields material properties in the warm dense matter regime. These measurements imply initial temperatures in the experimental samples over a range from 14 eV up to 40 eV; the sample densities varied from solid to a tenth solid density. Assuming an adiabatic expansion after the initial proton heating phase isentropes of the aluminium sample material were inferred and compared to tabulated data from the SESAME equation of state library. The proton spectrum was also measured using calibrated magnetic spectrometers and radiochromic film. The accuracy of the technique used to infer material data is discussed along with possible future development.

  1. Protonation Preferentially Stabilizes Minor Tautomers of the Halouracils: IRMPD Action Spectroscopy and Theoretical Studies

    NASA Astrophysics Data System (ADS)

    Crampton, K. T.; Rathur, A. I.; Nei, Y.-w.; Berden, G.; Oomens, J.; Rodgers, M. T.

    2012-09-01

    Tautomerization induced by protonation of halouracils may increase their efficacy as anti-cancer drugs by altering their reactivity and hydrogen bonding characteristics, potentially inducing errors during DNA and RNA replication. The gas-phase structures of protonated complexes of five halouracils, including 5-fluorouracil, 5-chlorouracil, 5-bromouracil, 5-iodouracil, and 6-chlorouracil are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical electronic structure calculations. IRMPD action spectra were measured for each complex in the IR fingerprint region extending from ~1000 to 1900 cm-1 using the free electron laser (FELIX). Correlations are made between the measured IRMPD action spectra and the linear IR spectra for the stable low-energy tautomeric conformations computed at the B3LYP/6-311+G(2d,2p)//B3LYP/6-31G* level of theory. Absence of an intense band(s) in the IRMPD spectrum arising from the carbonyl stretch(es) that are expected to appear near 1825 cm-1 provides evidence that protonation induces tautomerization and preferentially stabilizes alternative, noncanonical tautomers of these halouracils where both keto functionalities are converted to hydroxyl groups upon binding of a proton. The weak, but measurable absorption, which does occur for these systems near 1835 cm-1 suggests that in addition to the ground-state conformer, very minor populations of excited, low-energy conformers that contain keto functionalities are also present in these experiments.

  2. Microstructural evolution of RPV steels under proton and ion irradiation studied by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Wu, Y. C.; Liu, X. B.; Wang, R. S.; Nagai, Y.; Inoue, K.; Shimizu, Y.; Toyama, T.

    2015-03-01

    The microstructural evolution of reactor pressure vessel (RPV) steels induced by proton and heavy ion irradiation at low temperature (∼373 K) has been investigated using positron annihilation spectroscopy (PAS), atom probe tomography (APT), transmission electron microscopy (TEM) and nanoindentation. The PAS results indicated that both proton and heavy ion irradiation produce a large number of matrix defects, which contain small-size defects such as vacancies, vacancy-solute complexes, dislocation loops, and large-size vacancy clusters. In proton irradiated RPV steels, the size and number density of vacancy cluster defects increased rapidly with increasing dose due to the migration and agglomeration of vacancies. In contrast, for Fe ion irradiated steels, high density, larger size vacancy clusters can be easily induced at low dose, showing saturation in PAS response with increasing dose. No clear precipitates, solute-enriched clusters or other forms of solute segregation were observed by APT. Furthermore, dislocation loops were observed by TEM after 1.0 dpa, 240 keV proton irradiation, and an increase of the average nanoindentation hardness was found. It is suggested that ion irradiation produces many point defects and vacancy cluster defects, which induce the formation of dislocation loops and the increase of nanoindentation hardness.

  3. Protonation preferentially stabilizes minor tautomers of the halouracils: IRMPD action spectroscopy and theoretical studies.

    PubMed

    Crampton, K T; Rathur, A I; Nei, Y-w; Berden, G; Oomens, J; Rodgers, M T

    2012-09-01

    Tautomerization induced by protonation of halouracils may increase their efficacy as anti-cancer drugs by altering their reactivity and hydrogen bonding characteristics, potentially inducing errors during DNA and RNA replication. The gas-phase structures of protonated complexes of five halouracils, including 5-fluorouracil, 5-chlorouracil, 5-bromouracil, 5-iodouracil, and 6-chlorouracil are examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical electronic structure calculations. IRMPD action spectra were measured for each complex in the IR fingerprint region extending from ~1000 to 1900 cm(-1) using the free electron laser (FELIX). Correlations are made between the measured IRMPD action spectra and the linear IR spectra for the stable low-energy tautomeric conformations computed at the B3LYP/6-311+G(2d,2p)//B3LYP/6-31G* level of theory. Absence of an intense band(s) in the IRMPD spectrum arising from the carbonyl stretch(es) that are expected to appear near 1825 cm(-1) provides evidence that protonation induces tautomerization and preferentially stabilizes alternative, noncanonical tautomers of these halouracils where both keto functionalities are converted to hydroxyl groups upon binding of a proton. The weak, but measurable absorption, which does occur for these systems near 1835 cm(-1) suggests that in addition to the ground-state conformer, very minor populations of excited, low-energy conformers that contain keto functionalities are also present in these experiments. PMID:22821195

  4. A Study of Spacecraft Charging Due to Exposure to Interplanetary Protons

    NASA Astrophysics Data System (ADS)

    Green, Nelson W.; Frederickson, A. Robb

    2006-01-01

    The interplanetary space environment is composed mostly of low energy (E < 100 keV) plasma from the solar wind and high energy (E > 1 MeV) protons from solar energetic particle events. Satellites orbiting Earth are shielded to some degree from these events by the Earth's magnetic field but spacecraft traveling between planets and space nuclear systems on the lunar or Martian surface are exposed to these solar protons directly. A major concern for spacecraft is bulk dielectric charging, a form of spacecraft charging that can lead to dielectric discharges, a form of internal electrostatic discharge (IESD) that can damage sensitive electronics. The majority of research regarding IESD has been concerned with the electrons in the space environment around the Earth and at Jupiter; little research has been done on the charging of spacecraft in interplanetary space due to solar event protons. This paper provides a review of the literature regarding IESD due to protons and presents the results of recent laboratory experiments. Topics for further research are also suggested.

  5. Anti-proton tune measurements for the Fall 1995 accelerator studies

    SciTech Connect

    Marriner, john; /Fermilab

    1996-04-01

    A system to measure the tunes of a single antiproton (or proton) bunch was built and has been commissioned. The system achieved high sensitivity with a novel closed-orbit suppression system. The use of high bandwidth directional pickpus and kickers in conjunction with precise timing gates enabled the measurement of the tune of a single bunch.

  6. Experimental study of ion-beam self-pinched transport for MeV protons

    SciTech Connect

    Neri, J.M.; Young, F.C.; Stephanakis, S.J.; Ottinger, P.F.; Rose, D.V.; Hinshelwood, D.D.; Weber, B.V.

    1999-07-01

    A 100-kA, 1.2-MeV proton beam from a pinch-reflex ion diode on the Gamble II accelerator is used to test the concept of self-pinched ion transport. Self-pinched transport (SPT) uses the self-generated magnetic field from the ion beam to radially confine the ion beam. A proton beam is injected through a 3-cm radius aperture covered with a 2-{micro}m thick polycarbonate foil into a 10-cm radius transport region. The transport region is filled with helium at pressures of 30--250 mTorr, vacuum (10{sup {minus}4} Torr), or 1-Torr air. The beam is diagnosed with witness plates, multiple-pinhole-camera imaging onto radiochromic film, time- and space-resolved proton-scattering, and with prompt-{gamma} and nuclear-activation from LiF targets. Witness-plates and the multiple-pinhole-camera are used to determine the size, location, and uniformity of the beam at different distances from the injection aperture. A beam global divergence of 200 mrad is measured at 15 cm. At 50 cm, the beam fills the transport region. At 110 cm and 100- to 200-mTorr helium, there is evidence of beam filamentation. The measured increase in protons is consistent with the physical picture for SPT, and comparisons with IPROP simulations are in qualitative agreement with the measurements.

  7. In Vitro Study of the Variable Effects of Proton Pump Inhibitors on Voriconazole

    PubMed Central

    Niece, Krista L.; Boyd, Natalie K.

    2015-01-01

    Voriconazole is a broad-spectrum antifungal agent used for the treatment of severe fungal infections. Maintaining therapeutic concentrations of 1 to 5.5 μg/ml is currently recommended to maximize the exposure-response relationship of voriconazole. However, this is challenging, given the highly variable pharmacokinetics of the drug, which includes metabolism by cytochrome P450 (CYP450) isotypes CYP2C19, CYP3A4, and CYP2C9, through which common metabolic pathways for many medications take place and which are also expressed in different isoforms with various metabolic efficacies. Proton pump inhibitors (PPIs) are also metabolized through these enzymes, making them competitive inhibitors of voriconazole metabolism, and coadministration with voriconazole has been reported to increase total voriconazole exposure. We examined the effects of five PPIs (rabeprazole, pantoprazole, lansoprazole, omeprazole, and esomeprazole) on voriconazole concentrations using four sets of human liver microsomes (HLMs) of different CYP450 phenotypes. Overall, the use of voriconazole in combination with any PPI led to a significantly higher voriconazole yield compared to that achieved with voriconazole alone in both pooled HLMs (77% versus 59%; P < 0.001) and individual HLMs (86% versus 76%; P < 0.001). The mean percent change in the voriconazole yield from that at the baseline after PPI exposure in pooled microsomes ranged from 22% with pantoprazole to 51% with esomeprazole. Future studies are warranted to confirm whether and how the deliberate coadministration of voriconazole and PPIs can be used to boost voriconazole levels in patients with difficult-to-treat fungal infections. PMID:26124167

  8. Glutamate/glutamine and neuronal integrity in adults with ADHD: a proton MRS study

    PubMed Central

    Maltezos, S; Horder, J; Coghlan, S; Skirrow, C; O'Gorman, R; Lavender, T J; Mendez, M A; Mehta, M; Daly, E; Xenitidis, K; Paliokosta, E; Spain, D; Pitts, M; Asherson, P; Lythgoe, D J; Barker, G J; Murphy, D G

    2014-01-01

    There is increasing evidence that abnormalities in glutamate signalling may contribute to the pathophysiology of attention-deficit hyperactivity disorder (ADHD). Proton magnetic resonance spectroscopy ([1H]MRS) can be used to measure glutamate, and also its metabolite glutamine, in vivo. However, few studies have investigated glutamate in the brain of adults with ADHD naive to stimulant medication. Therefore, we used [1H]MRS to measure the combined signal of glutamate and glutamine (Glu+Gln; abbreviated as Glx) along with other neurometabolites such as creatine (Cr), N-acetylaspartate (NAA) and choline. Data were acquired from three brain regions, including two implicated in ADHD—the basal ganglia (caudate/striatum) and the dorsolateral prefrontal cortex (DLPFC)—and one ‘control' region—the medial parietal cortex. We compared 40 adults with ADHD, of whom 24 were naive for ADHD medication, whereas 16 were currently on stimulants, against 20 age, sex and IQ-matched healthy controls. We found that compared with controls, adult ADHD participants had a significantly lower concentration of Glx, Cr and NAA in the basal ganglia and Cr in the DLPFC, after correction for multiple comparisons. There were no differences between stimulant-treated and treatment-naive ADHD participants. In people with untreated ADHD, lower basal ganglia Glx was significantly associated with more severe symptoms of inattention. There were no significant differences in the parietal ‘control' region. We suggest that subcortical glutamate and glutamine have a modulatory role in ADHD adults; and that differences in glutamate–glutamine levels are not explained by use of stimulant medication. PMID:24643164

  9. Glutamate/glutamine and neuronal integrity in adults with ADHD: a proton MRS study.

    PubMed

    Maltezos, S; Horder, J; Coghlan, S; Skirrow, C; O'Gorman, R; Lavender, T J; Mendez, M A; Mehta, M; Daly, E; Xenitidis, K; Paliokosta, E; Spain, D; Pitts, M; Asherson, P; Lythgoe, D J; Barker, G J; Murphy, D G

    2014-01-01

    There is increasing evidence that abnormalities in glutamate signalling may contribute to the pathophysiology of attention-deficit hyperactivity disorder (ADHD). Proton magnetic resonance spectroscopy ([1H]MRS) can be used to measure glutamate, and also its metabolite glutamine, in vivo. However, few studies have investigated glutamate in the brain of adults with ADHD naive to stimulant medication. Therefore, we used [1H]MRS to measure the combined signal of glutamate and glutamine (Glu+Gln; abbreviated as Glx) along with other neurometabolites such as creatine (Cr), N-acetylaspartate (NAA) and choline. Data were acquired from three brain regions, including two implicated in ADHD-the basal ganglia (caudate/striatum) and the dorsolateral prefrontal cortex (DLPFC)-and one 'control' region-the medial parietal cortex. We compared 40 adults with ADHD, of whom 24 were naive for ADHD medication, whereas 16 were currently on stimulants, against 20 age, sex and IQ-matched healthy controls. We found that compared with controls, adult ADHD participants had a significantly lower concentration of Glx, Cr and NAA in the basal ganglia and Cr in the DLPFC, after correction for multiple comparisons. There were no differences between stimulant-treated and treatment-naive ADHD participants. In people with untreated ADHD, lower basal ganglia Glx was significantly associated with more severe symptoms of inattention. There were no significant differences in the parietal 'control' region. We suggest that subcortical glutamate and glutamine have a modulatory role in ADHD adults; and that differences in glutamate-glutamine levels are not explained by use of stimulant medication. PMID:24643164

  10. In vitro study of the variable effects of proton pump inhibitors on voriconazole.

    PubMed

    Niece, Krista L; Boyd, Natalie K; Akers, Kevin S

    2015-09-01

    Voriconazole is a broad-spectrum antifungal agent used for the treatment of severe fungal infections. Maintaining therapeutic concentrations of 1 to 5.5 μg/ml is currently recommended to maximize the exposure-response relationship of voriconazole. However, this is challenging, given the highly variable pharmacokinetics of the drug, which includes metabolism by cytochrome P450 (CYP450) isotypes CYP2C19, CYP3A4, and CYP2C9, through which common metabolic pathways for many medications take place and which are also expressed in different isoforms with various metabolic efficacies. Proton pump inhibitors (PPIs) are also metabolized through these enzymes, making them competitive inhibitors of voriconazole metabolism, and coadministration with voriconazole has been reported to increase total voriconazole exposure. We examined the effects of five PPIs (rabeprazole, pantoprazole, lansoprazole, omeprazole, and esomeprazole) on voriconazole concentrations using four sets of human liver microsomes (HLMs) of different CYP450 phenotypes. Overall, the use of voriconazole in combination with any PPI led to a significantly higher voriconazole yield compared to that achieved with voriconazole alone in both pooled HLMs (77% versus 59%; P < 0.001) and individual HLMs (86% versus 76%; P < 0.001). The mean percent change in the voriconazole yield from that at the baseline after PPI exposure in pooled microsomes ranged from 22% with pantoprazole to 51% with esomeprazole. Future studies are warranted to confirm whether and how the deliberate coadministration of voriconazole and PPIs can be used to boost voriconazole levels in patients with difficult-to-treat fungal infections. PMID:26124167

  11. The Kynurenine Pathway in Adolescent Depression: Preliminary Findings from a Proton MR Spectroscopy Study

    PubMed Central

    Gabbay, Vilma; Liebes, Leonard; Katz, Yisrael; Liu, Songtao; Mendoza, Sandra; Babb, James S.; Klein, Rachel G.; Gonen, Oded

    2009-01-01

    Background Cytokine induction of the enzyme indoleamine 2,3-dioxygenase (IDO) has been implicated in the development of major depressive disorder (MDD). IDO metabolizes tryptophan (TRP) into kynurenine (KYN), thereby decreasing TRP availability to the brain. KYN is further metabolized into several neurotoxins. The aims of this pilot were to examine possible relationships between plasma TRP, KYN, and 3-hydroxyanthranilic acid (3-HAA, neurotoxic metabolite) and striatal total choline (tCho, cell membrane turnover biomarker) in adolescents with MDD. We hypothesized that MDD adolescents would exhibit: i) positive correlations between KYN and 3-HAA and striatal tCho and a negative correlation between TRP and striatal tCho; and, ii) the anticipated correlations would be more pronounced in the melancholic subtype group. Methods Fourteen adolescents with MDD (seven with melancholic features) and six healthy controls were enrolled. Minimums of 6 weeks MDD duration and a severity score of 40 on the Children’s Depression Rating Scale-Revised were required. All were scanned at 3 Tesla with MRI, multi-voxel 3-dimensional, high, 0.75 cm3, spatial resolution proton magnetic resonance spectroscopic imaging. Striatal tCho concentrations were assessed using phantom replacement. Spearman correlation coefficients were Bonferroni-corrected. Results Positive correlations were found only in the melancholic group, between KYN and 3-HAA and tCho in the right caudate (r=0.93, p=0.03) and the left putamen (r=0.96, p=.006), respectively. Conclusions These preliminary findings suggest a possible role of the KYN pathway in adolescent melancholic MDD. Larger studies should follow. PMID:19778568

  12. Studying shock dynamics and in-flight ρR asymmetries in NIF implosions using proton spectroscopy

    NASA Astrophysics Data System (ADS)

    Zylstra, Alex

    2014-10-01

    Ignition-scale, indirect-drive implosions of CH capsules filled with D3He gas have been studied with proton spectroscopy at the NIF. Spectral measurements of D3He protons produced at the shock-bang time provide information about the shock dynamics and in-flight characteristics of these implosions. The observed energy downshift of the D3He-proton spectra are interpreted with a self-consistent 1-D model to infer ρR, shell Rcm, and yield at this time. The observed ρR at shock-bang time is substantially higher for implosions where the laser drive is on until near the compression-bang time (``short-coast'') while longer-coasting implosions generate lower ρR at shock-bang time. This is most likely due to a larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast implosions (~400 ps). These differences are determined from the D3He proton spectra and in-flight x-ray radiography data, and it is found to contradict radiation-hydrodynamic simulations, which predict a 700-800 ps temporal difference independent of coasting time. A large variation in the shock proton yield is also observed in the dataset, which is interpreted with a Guderley shock model and found to correspond to ~2× variation in incipient hot-spot adiabat caused by shock heating. This variation may affect the compressibility of NIF implosions. Finally, data from multiple proton spectrometers placed at the pole and equator reveal large ρR asymmetries, which are interpreted as mode-2 polar or azimuthal asymmetries. At the shock-bang time (CR ~ 3-5), asymmetry amplitudes >=10% are routinely observed. Compared to compression-bang time x-ray self-emission symmetry, no apparent asymmetry-amplitude growth is observed, which is in contradiction to several growth models. This is attributed to a lack of correspondence between shell and hot-spot symmetry at peak compression, as discussed in recent computational studies. This work was

  13. 1H NMR study of proton motion in hydrogen-bonded chain in Mannich base of 5,5'-dibromo-3-diethylaminomethyl-2,2'-biphenol

    NASA Astrophysics Data System (ADS)

    Wojciechowski, G.; Rozwadowski, Z.; Dziembowska, T.; Brzezinski, B.

    2001-01-01

    5,5'-dibromo-3-diethylaminomethyl-2,2'-biphenol was synthesized and the collective proton motion in two intramolecular hydrogen bonds was studied by 1H and 13C NMR as well as by FTIR spectroscopy in chloroform, acetonitrile and chloroform containing traces of water solutions. In dry chloroform, always, two separated proton signals for the two OH groups were observed. If traces of water were present at room temperature in the chloroform solution only one signal for the two OH protons was found. With decreasing temperature the collective proton motion, indicated by continuous absorption in the FTIR spectrum, was interrupted and two separate signals appeared in the 1H NMR spectrum. In acetonitrile the collective proton motion in the two intramolecular hydrogen-bonded system observed at room temperature vanished with decreasing temperature and finally only a cooperative hydrogen-bonded system, like in the solid state, was observed.

  14. Computer simulation dose studies in heterogeneous media for electron and proton beam radiotherapy of static and moving targets

    NASA Astrophysics Data System (ADS)

    Lee, Tae Kyu

    The energy-dependent electron loss model (ELM) and proton loss model (PLM) have been developed to predict dose deposition in heterogeneous slab media. Predictions of dose deposition in heterogeneous slab media are compared to the Monte Carlo calculations and experimental measurements. Slab media studied comprised water/bone/water and water/lung/water and incident beam energies between 10MeV and 18MeV for electron beams and 100MeV and 160MeV for proton beams. Dose discrepancies at large depths beyond the interface were within 5% of maximum dose. This error may be attributed to the assumption of a Gaussian energy distribution for the charge particles at depth. The computational cost is low compared to Monte Carlo simulations making the ELM and PLM attractive as a fast dose engine for dose optimization algorithms. To simulate a more realistic and challenging clinical treatment, a mathematical 3-D phantom was defined to simulate inferior-superior motion of a lung tumor target. Lung size and density change during the breathing cycle was modeled from full inspiration to full expiration. Sensitivity to dose error due to the respiratory motion of the target and the right lung, defined as the organ at risk (OAR), was studied for intensity modulated proton therapy (IMPT) and intensity modulated x-ray therapy (IMXT). Effects of rotational or lateral setup error on the dose distribution were studied independently and simultaneously with breathing.

  15. Reduced side effects by proton microchannel radiotherapy: study in a human skin model.

    PubMed

    Zlobinskaya, Olga; Girst, Stefanie; Greubel, Christoph; Hable, Volker; Siebenwirth, Christian; Walsh, Dietrich W M; Multhoff, Gabriele; Wilkens, Jan J; Schmid, Thomas E; Dollinger, Günther

    2013-03-01

    The application of a microchannel proton irradiation was compared to homogeneous irradiation in a three-dimensional human skin model. The goal is to minimize the risk of normal tissue damage by microchannel irradiation, while preserving local tumor control through a homogeneous irradiation of the tumor that is achieved because of beam widening with increasing track length. 20 MeV protons were administered to the skin models in 10- or 50-μm-wide irradiation channels on a quadratic raster with distances of 500 μm between each channel (center to center) applying an average dose of 2 Gy. For comparison, other samples were irradiated homogeneously at the same average dose. Normal tissue viability was significantly enhanced after microchannel proton irradiation compared to homogeneous irradiation. Levels of inflammatory parameters, such as Interleukin-6, TGF-Beta, and Pro-MMP1, were significantly lower in the supernatant of the human skin tissue after microchannel irradiation than after homogeneous irradiation. The genetic damage as determined by the measurement of micronuclei in keratinocytes also differed significantly. This difference was quantified via dose modification factors (DMF) describing the effect of each irradiation mode relative to homogeneous X-ray irradiation, so that the DMF of 1.21 ± 0.20 after homogeneous proton irradiation was reduced to 0.23 ± 0.11 and 0.40 ± 0.12 after microchannel irradiation using 10- and 50-μm-wide channels, respectively. Our data indicate that proton microchannel irradiation maintains cell viability while significantly reducing inflammatory responses and genetic damage compared to homogeneous irradiation, and thus might improve protection of normal tissue after irradiation. PMID:23271171

  16. Proton Beam Therapy as a Nonsurgical Approach to Mucosal Melanoma of the Head and Neck: A Pilot Study

    SciTech Connect

    Zenda, Sadamoto; Kawashima, Mitsuhiko; Nishio, Teiji; Kohno, Ryosuke; Nihei, Keiji; Onozawa, Masakatsu; Arahira, Satoko; Ogino, Takashi

    2011-09-01

    Purpose: The aim of this pilot study was to assess the clinical benefit of proton beam therapy for mucosal melanoma of the head and neck. Methods and Materials: Patients with mucosal melanoma of the head and neck with histologically confirmed malignant melanoma and N0 and M0 disease were enrolled. Proton therapy was delivered three times per week with a planned total dose of 60 Gy equivalents (GyE) in 15 fractions. Results: Fourteen consecutive patients were enrolled from January 2004 through February 2008. Patient characteristics were as follows: median age 73 years old (range, 56 to 79 years); male/female ratio, 7/7; and T stage 1/2/3/4, 3/2/0/9. All patients were able to receive the full dose of proton therapy. The most common acute toxicities were mucositis (grade 3, 21%) and mild dermatitis (grade 3, 0%). As for late toxicity, 2 patients had a unilateral decrease in visual acuity, although blindness did not occur. No treatment-related deaths occurred throughout the study. Initial local control rate was 85.7%, and, with a median follow-up period of 36.7 months, median progression-free survival was 25.1 months, and 3-year overall survival rates were 58.0%. The most frequent site of first failure was cervical lymph nodes (6 patients), followed by local failure in 1 patient and lung metastases in 1 patient. On follow-up, 5 patients died of disease, 4 died due to cachexia caused by distant metastases, and 1 patient by carotid artery perforation cause by lymph nodes metastases. Conclusions: Proton beam radiotherapy showed promising local control benefits and would benefit from ongoing clinical study.

  17. Study of double parton scattering using W + 2-jet events in proton-proton collisions at $$\\sqrt{s}$$ = 7 TeV

    DOE PAGESBeta

    Chatrchyan, Serguei

    2014-03-05

    Double parton scattering is investigated in proton-proton collisions at √s = 7 TeV where the final state includes a W boson, which decays into a muon and a neutrino, and two jets. The data sample corresponds to an integrated luminosity of 5 fb–1, collected with the CMS detector at the LHC. Observables sensitive to double parton scattering are investigated after being corrected for detector effects and selection efficiencies. The fraction of W + 2-jet events due to double parton scattering is measured to be 0.055 +/- 0.002 (stat.) +/- 0.014 (syst.). Finally, the effective cross section, σeff, characterizing the effectivemore » transverse area of hard partonic interactions in collisions between protons is measured to be 20.7 +/- 0.8 (stat.) +/- 6.6 (syst.) mb.« less

  18. Study of double parton scattering using W + 2-jet events in proton-proton collisions at $\\sqrt{s}$ = 7 TeV

    SciTech Connect

    Chatrchyan, Serguei

    2014-03-05

    Double parton scattering is investigated in proton-proton collisions at √s = 7 TeV where the final state includes a W boson, which decays into a muon and a neutrino, and two jets. The data sample corresponds to an integrated luminosity of 5 fb–1, collected with the CMS detector at the LHC. Observables sensitive to double parton scattering are investigated after being corrected for detector effects and selection efficiencies. The fraction of W + 2-jet events due to double parton scattering is measured to be 0.055 +/- 0.002 (stat.) +/- 0.014 (syst.). Finally, the effective cross section, σeff, characterizing the effective transverse area of hard partonic interactions in collisions between protons is measured to be 20.7 +/- 0.8 (stat.) +/- 6.6 (syst.) mb.

  19. Dating Archean zircon by ion microprobe: New light on an old problem

    NASA Technical Reports Server (NTRS)

    Williams, I. S.; Kinny, P. D.; Black, L. P.; Compston, W.; Froude, D. O.; Ireland, T. R.

    1985-01-01

    Ion microprobe analysis of zircons from three sites (Watersmeet Dome in northern Michigan, Mount Sones in eastern Antarctica, and Mount Narryer in western Australia) is discussed. Implications of the results to Archean geochronology and early Earth crust composition are addressed.

  20. Laser microprobe facility used in the elemental analysis of small feature of a sample

    NASA Technical Reports Server (NTRS)

    Baldwin, J. M.

    1969-01-01

    Laser microprobe facility is effective in the elemental analysis of small areas of heterogeneous samples. The instrument uses the focused beam of a pulsed laser to evaporate a small volume of material from a relatively massive sample.

  1. Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hadjiev, V. G.; Arepalli, S.; Nikolaev, P.; Jandl, S.; Yowell, L.

    2003-01-01

    We explore Raman microprobe capabilities to visualize single wall carbon nanotubes (SWCNTs). Although this technique is limited to a micron scale, we demonstrate that images of individual SWCNTs, bundles or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman response from carbon vibrations in SWCNTs excited by confocal scanning of a focused laser beam. Carbon vibrations reveal key characteristics of SWCNTs as nanotube diameter distribution (radial breathing modes, RBM, 100-300 cm(exp -1)), presence of defects and functional groups (D-mode, 1300-1350 cm(exp -1)), strain and oxidation states of SWCNTs, as well as metallic or semiconducting character of the tubes encoded in the lineshape of the G-modes at 1520-1600 cm(exp - 1). In addition, SWCNTs are highly anisotropic scatterers. The Raman response from a SWCNT is maximal for incident light polarization parallel to the tube axis and vanishing for perpendicular directions. We show that the SWCNT bundle shape or direction can be determined, with some limitations, from a set of Raman images taken at two orthogonal directions of the incident light polarization.

  2. Light stable isotope analysis of meteorites by ion microprobe

    NASA Technical Reports Server (NTRS)

    Mcsween, Harry Y., Jr.

    1994-01-01

    The main goal was to develop the necessary secondary ion mass spectrometer (SIMS) techniques to use a Cameca ims-4f ion microprobe to measure light stable isotope ratios (H, C, O and S) in situ and in non-conducting mineral phases. The intended application of these techniques was the analysis of meteorite samples, although the techniques that have been developed are equally applicable to the investigation of terrestrial samples. The first year established techniques for the analysis of O isotope ratios (delta O-18 and delta O-17) in conducting mineral phases and the measurement of S isotope ratios (delta S-34) in a variety of sulphide phases. In addition, a technique was developed to measure delta S-34 values in sulphates, which are insulators. Other research undertaken in the first year resulted in SIMS techniques for the measurement of wide variety of trace elements in carbonate minerals, with the aim of understanding the nature of alteration fluids in carbonaceous chondrites. In the second year we developed techniques for analyzing O isotope ratios in nonconducting mineral phases. These methods are potentially applicable to the measurement of other light stable isotopes such as H, C and S in insulators. Also, we have further explored the analytical techniques used for the analysis of S isotopes in sulphides by analyzing troilite in a number of L and H ordinary chondrites. This was done to see if there was any systematic differences with petrological type.

  3. An integrated computer system for Fudan nuclear microprobe

    NASA Astrophysics Data System (ADS)

    Zou, Degang; Ren, Chigang; Tang, Jiayong; Yang, Fujia

    1995-09-01

    With the help of modern personal computer (PC) and object oriented programming (OOP) technology, we have recently developed a compact, integrated, user-friendly computer system for Fudan nuclear microprobe, which was originally modeled after the SUNY/Albany system. The system software has been thoroughly rewritten so as to take advantage of today's high-performance PC and facilitate easy upgrading and expansion in the case of future development of both hardware and software. Most functions of this system such as sample searching, scanning control, data acquisition, image processing and displaying, are based on a single 80386 IBM style PC with a 1-MB DRAM TVGA high-resolution monitor. Data from up to 4 ADCs, 4 sensors and a CCD camera can be acquired simultaneously. Two stepper motors are employed to move the target; a CCD camera system is also included to locate the area of interest on the sample; the secondary electron image could act as a reference to fine adjustment. Rectangular raster scanning or irregular scanning is facilitated with beam motion triggered either by a timer or by pulses from a current integrator. A variety of built-in image displaying, processing and printing methods have also been implemented in order to make the maps easier to interpret for the eyes. All of these functions are administrated by an integrated, completely menu-driven software package-MBSYS.

  4. Ab initio study of the molecular structure and vibrational spectrum of nitric acid and its protonated forms

    NASA Technical Reports Server (NTRS)

    Lee, Timothy J.; Rice, Julia E.

    1992-01-01

    The equilibrium structures, harmonic vibrational frequencies, IR intensities, and relative energetics of HNO3 and its protonated form H2NO3+ were investigated using double-zeta plus polarization and triple-zeta plus polarization basis sets in conjunction with high-level ab initio methods. The latter include second-order Moller-Plesset perturbation theory, the single and double excitation coupled cluster (CCSD) methods, a perturbational estimate of the effects of connected triple excitations (CCSD(T)), and the self-consistent field. To determine accurate energy differences CCSD(T) energies were computed using large atomic natural orbital basis sets. Four different isomers of H2NO3+ were considered. The lowest energy form of protonated nitric acid was found to correspond to a complex between H2O and NO2+, which is consistent with earlier theoretical and experimental studies.

  5. Possibilities of studying the structure of halo nuclei in reactions of quasifree proton scattering at low energies

    SciTech Connect

    Zuyev, S. V. Kasparov, A. A.; Konobeevski, E. S.

    2015-07-15

    The possibility of experimentally studying the structure of halo nuclei in reactions induced by quasifree proton scattering on clusters of these nuclei is considered. Quasifree proton scattering on {sup 6}He, {sup 4}He, {sup 4}n, {sup 2}n, and n clusters in inverse kinematics is considered for the example of the {sup 8}He nucleus. Angular and energy distributions of secondaries are obtained for various representations of the cluster structure of the {sup 8}He nucleus. It is clearly shown that, in the angular and energy distributions of secondaries, one can single out regions that receive dominant contributions from reactions on specific clusters and which correspond to concrete cluster configurations of halo nuclei. Possible relevant experiments are proposed.

  6. Ab initio study of the chlorine nitrate protonation reaction - Implications for loss of ClONO2 in the stratosphere

    NASA Technical Reports Server (NTRS)

    Lee, Timothy J.; Rice, Julia E.

    1993-01-01

    Ab initio quantum mechanical methods, including coupled-cluster theory, are used to determine the equilibrium geometries, dipole moments, and harmonic vibrational frequencies of ClONO2, NO2(+), and four isomers of protonated ClONO2. It was found that, for the equilibrium structures and harmonic frequencies of ClONO2, HOCl, and NO2(+), the highest-level theoretical predictions are consistent with the available experimental information concerning the reactions of ClONO2 and HOCl with HCl on the surface of polar stratospheric clouds (PSCs). The study supports a recent hypothesis that the reaction of ClONO2 on the surface of PSCs is proton catalyzed, although the mechanism is different.

  7. Nitrogen and Hydrogen on a Palladium-covered proton conductor: a first principle study of Ammonia catalysis

    NASA Astrophysics Data System (ADS)

    Paulatto, Lorenzo; de Gironcoli, Stefano

    2009-03-01

    Being liquid at ambient conditions Ammonia would be an ideal Hydrogen vector. However, the industrial Haber process for Ammonia synthesis involves high pressures ( 100 bar) and temperatures (450-500 ^oC), making the process very expensive. Recently, ambient pressure Ammonia production, in the 570-750 ^oC temperature range, has been reported at the Palladium cathode of a proton conducting cell-reactor [1]. The rate limiting step in the Haber process is N2 dissociation, while the observed limiting factor in Ref. [1] appears to be the proton transfer through the conductor and it has been proposed that Nitrogen hydrogenation may in this case precede dissociation. We use first-principles techniques to study Nitrogen, Hydrogen and Ammonia interaction with flat and stepped Pd surfaces, in presence of external electric fields. Our aim is to study the effect of electrochemically provided protons on the catalysis of the reaction. [1]G. Marnellos and M. Stoukides, Science 282, 98 (1998); G. Marnellos, S. Zisekas, and M. Stoukides, J. of Catalysis 193, 80-87 (2000)

  8. Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators.

    PubMed

    Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

    2016-01-01

    This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. PMID:25628454

  9. The effects of tautomerization and protonation on the adenine-cytosine mismatches: a density functional theory study.

    PubMed

    Masoodi, Hamid Reza; Bagheri, Sotoodeh; Abareghi, Mahsa

    2016-06-01

    In the present work, we demonstrate the results of a theoretical study concerned with the question how tautomerization and protonation of adenine affect the various properties of adenine-cytosine mismatches. The calculations, in gas phase and in water, are performed at B3LYP/6-311++G(d,p) level. In gas phase, it is observed that any tautomeric form of investigated mismatches is more stabilized when adenine is protonated. As for the neutral mismatches, the mismatches containing amino form of cytosine and imino form of protonated adenine are more stable. The role of aromaticity on the stability of tautomeric forms of mismatches is investigated by NICS(1)ZZ index. The stability of mispairs decreases by going from gas phase to water. It can be explained using dipole moment parameter. The influence of hydrogen bonds on the stability of mismatches is examined by atoms in molecules and natural bond orbital analyses. In addition to geometrical parameters and binding energies, the study of the topological properties of electron charge density aids in better understanding of these mispairs. PMID:26198186

  10. Proton Pump Inhibitors and Hospitalization with Hypomagnesemia: A Population-Based Case-Control Study

    PubMed Central

    Zipursky, Jonathan; Macdonald, Erin M.; Hollands, Simon; Gomes, Tara; Mamdani, Muhammad M.; Paterson, J. Michael; Lathia, Nina; Juurlink, David N.

    2014-01-01

    Background Some evidence suggests that proton pump inhibitors (PPIs) are an under-appreciated risk factor for hypomagnesemia. Whether hospitalization with hypomagnesemia is associated with use of PPIs is unknown. Methods and Findings We conducted a population-based case-control study of multiple health care databases in Ontario, Canada, from April 2002 to March 2012. Patients who were enrolled as cases were Ontarians aged 66 years or older hospitalized with hypomagnesemia. For each individual enrolled as a case, we identified up to four individuals as controls matched on age, sex, kidney disease, and use of various diuretic classes. Exposure to PPIs was categorized according to the most proximate prescription prior to the index date as current (within 90 days), recent (within 91 to 180 days), or remote (within 181 to 365 days). We used conditional logistic regression to estimate the odds ratio for the association of outpatient PPI use and hospitalization with hypomagnesemia. To test the specificity of our findings we examined use of histamine H2 receptor antagonists, drugs with no causal link to hypomagnesemia. We studied 366 patients hospitalized with hypomagnesemia and 1,464 matched controls. Current PPI use was associated with a 43% increased risk of hypomagnesemia (adjusted odds ratio, 1.43; 95% CI 1.06–1.93). In a stratified analysis, the risk was particularly increased among patients receiving diuretics, (adjusted odds ratio, 1.73; 95% CI 1.11–2.70) and not significant among patients not receiving diuretics (adjusted odds ratio, 1.25; 95% CI 0.81–1.91). We estimate that one excess hospitalization with hypomagnesemia will occur among 76,591 outpatients treated with a PPI for 90 days. Hospitalization with hypomagnesemia was not associated with the use of histamine H2 receptor antagonists (adjusted odds ratio 1.06; 95% CI 0.54–2.06). Limitations of this study include a lack of access to serum magnesium levels, uncertainty regarding diagnostic coding of

  11. Study of 180 Mev Proton Inelastic Scattering from SILICON-28 and SILICON-30.

    NASA Astrophysics Data System (ADS)

    Chen, Quan

    This thesis reports the measurement of cross section and analyzing power angular distribution of elastic and inelastic scattering of 180 MeV proton for ^ {28}Si and ^{30} Si. Measurements were carried out using the proton beam available at the Indiana University Cyclotron Facility. The scattered protons were detected using the QDDM magnetic spectrometer. The DWIA framework, in which most inelastic proton scattering observables are analyzed, has three ingredients, (1) NN-effective interaction, (2) transition density, and (3) distorted waves. The procedure used here to obtain effective NN-interaction empirically is that first suggested by J. J. Kelly. It models effective NN-interaction guided by the nuclear matter theory(G-matrix) and employs the local density approximation(LDA). By using the transitions, for which transition densities are known, it fits the inelastic observable to determine the parameters used to model the momentum transfer(q) and density(k_{F }) dependence of the effective interaction (here reference to as empirical interaction). The distorted waves are calculated in a self-consistent manner from the model empirical interaction. The salient results are: (1) It is observed that, although the data base was increased by combining the ^{16}O observable with those of ^{28}Si, it still was not large enough to determine all the parameters without ambiguity in terms of which the effective NN-interaction was modeled. (2) The model prediction of cross section and analyzing power in terms of DWIA, using both the Paris -g and empirical interaction, with the observed are compared. It is clear that the results and the technique used to obtain effective NN-interaction shows that there is substantial potential to gain both qualitative and quantitative insight into how the interaction between two nucleons is modified within the nuclear medium. In particular, at low-q effective interaction is reduced and at high-q repulsion is enhanced compared to free interaction

  12. Elemental distribution and sample integrity comparison of freeze-dried and frozen-hydrated biological tissue samples with nuclear microprobe

    NASA Astrophysics Data System (ADS)

    Vavpetič, P.; Vogel-Mikuš, K.; Jeromel, L.; Ogrinc Potočnik, N.; Pongrac, P.; Drobne, D.; Pipan Tkalec, Ž.; Novak, S.; Kos, M.; Koren, Š.; Regvar, M.; Pelicon, P.

    2015-04-01

    The analysis of biological samples in frozen-hydrated state with micro-PIXE technique at Jožef Stefan Institute (JSI) nuclear microprobe has matured to a point that enables us to measure and examine frozen tissue samples routinely as a standard research method. Cryotome-cut slice of frozen-hydrated biological sample is mounted between two thin foils and positioned on the sample holder. The temperature of the cold stage in the measuring chamber is kept below 130 K throughout the insertion of the samples and the proton beam exposure. Matrix composition of frozen-hydrated tissue is consisted mostly of ice. Sample deterioration during proton beam exposure is monitored during the experiment, as both Elastic Backscattering Spectrometry (EBS) and Scanning Transmission Ion Microscopy (STIM) in on-off axis geometry are recorded together with the events in two PIXE detectors and backscattered ions from the chopper in a single list-mode file. The aim of this experiment was to determine differences and similarities between two kinds of biological sample preparation techniques for micro-PIXE analysis, namely freeze-drying and frozen-hydrated sample preparation in order to evaluate the improvements in the elemental localisation of the latter technique if any. In the presented work, a standard micro-PIXE configuration for tissue mapping at JSI was used with five detection systems operating in parallel, with proton beam cross section of 1.0 × 1.0 μm2 and a beam current of 100 pA. The comparison of the resulting elemental distributions measured at the biological tissue prepared in the frozen-hydrated and in the freeze-dried state revealed differences in elemental distribution of particular elements at the cellular level due to the morphology alteration in particular tissue compartments induced either by water removal in the lyophilisation process or by unsatisfactory preparation of samples for cutting and mounting during the shock-freezing phase of sample preparation.

  13. Proton interrogation

    SciTech Connect

    Morris, Christopher L

    2008-01-01

    Energetic proton beams may provide an attractive alternative when compared to electromagnetic and neutron beams for active interrogation of nuclear threats because: they have large fission cross sections, long mean free paths and high penetration, and proton beams can be manipulated with magnetic optics. We have measured time-dependent cross sections for delayed neutrons and gamma-rays using the 800 MeV proton beam from the Los Alamos Neutron Science Center for a set of bare and shielded targets. The results show significant signals from both unshielded and shielded nuclear materials. Results will be presented.

  14. Flash Proton Radiography

    NASA Astrophysics Data System (ADS)

    Merrill, Frank E.

    Protons were first investigated as radiographic probes as high energy proton accelerators became accessible to the scientific community in the 1960s. Like the initial use of X-rays in the 1800s, protons were shown to be a useful tool for studying the contents of opaque materials, but the electromagnetic charge of the protons opened up a new set of interaction processes which complicated their use. These complications in combination with the high expense of generating protons with energies high enough to penetrate typical objects resulted in proton radiography becoming a novelty, demonstrated at accelerator facilities, but not utilized to their full potential until the 1990s at Los Alamos. During this time Los Alamos National Laboratory was investigating a wide range of options, including X-rays and neutrons, as the next generation of probes to be used for thick object flash radiography. During this process it was realized that the charge nature of the protons, which was the source of the initial difficulty with this idea, could be used to recover this technique. By introducing a magnetic imaging lens downstream of the object to be radiographed, the blur resulting from scattering within the object could be focused out of the measurements, dramatically improving the resolution of proton radiography of thick systems. Imaging systems were quickly developed and combined with the temporal structure of a proton beam generated by a linear accelerator, providing a unique flash radiography capability for measurements at Los Alamos National Laboratory. This technique has now been employed at LANSCE for two decades and has been adopted around the world as the premier flash radiography technique for the study of dynamic material properties.

  15. Performance of missing transverse momentum reconstruction in ATLAS studied in proton-proton collisions in 2012 at 8 TeV

    NASA Astrophysics Data System (ADS)

    March, Luis

    2015-10-01

    The missing transverse energy plays a really important role in reconstructing events produced at hadron colliders. Undetectable particles, such as neutrinos, pass through the matter with a negligible probability of interaction. Hence, no direct evidence of them can be measured in a general purpose detector, as ATLAS. However, the total momenta in the transverse plane to the beam axis has to be conserved and computed. In particular, it is used in searches for the Standard Model Higgs boson channels, such as: H → WW, H → ZZ and H → ττ. The benefit of using this conservation law is that an energy imbalance may signal the presence of such undetectable particles. Therefore, it becomes also a powerful tool for new physics searches at the Large Hadron Collider, such as Supersymmetry and Extra Dimensions. The performance of the missing transverse momentum reconstruction in the ATLAS detector is evaluated using data collected in 2012 in proton-proton collisions at a centre-of-mass energy of 8 TeV. An optimised reconstruction of missing transverse momentum is used and the effects arising from additional proton-proton interactions superimposed on the hard physics process are suppressed with various methods. Results are shown for a data sample corresponding to an integrated luminosity of about 20 ft-1 and for events with different topologies with or without a genuine missing transverse momentum due to undetected particles.

  16. Rectal Toxicity After Proton Therapy For Prostate Cancer: An Analysis of Outcomes of Prospective Studies Conducted at the University of Florida Proton Therapy Institute

    SciTech Connect

    Colaco, Rovel J.; Hoppe, Bradford S.; Flampouri, Stella; McKibben, Brian T.; Henderson, Randal H.; Bryant, Curtis; Nichols, Romaine C.; Mendenhall, William M.; Li, Zuofeng; Su, Zhong; Morris, Christopher G.; Mendenhall, Nancy P.

    2015-01-01

    Purpose: Study goals were to characterize gastrointestinal effects of proton therapy (PT) in a large cohort of patients treated for prostate cancer, identify factors associated with rectal bleeding (RB), and compare RB between patients receiving investigational protocols versus those in outcome-tracking protocols. Methods and Materials: A total of 1285 consecutive patients were treated with PT between August 2006 and May 2010. Potential pre-existing clinical and treatment-related risk factors for rectal toxicity were recorded. Common Terminology Criteria for Adverse Events version 3.0 was used to score toxicity. Results: Transient RB was the predominant grade 2 or higher (GR2+) toxicity after PT, accounting for 95% of gastrointestinal events. GR1 RB occurred in 217 patients (16.9%), GR2 RB in 187 patients (14.5%), and GR3 in 11 (0.9%) patients. There were no GR4 or GR5 events. Univariate analyses showed correlations between GR2+ RB and anticoagulation therapy (P=.008) and rectal and rectal wall dose-volume histogram (DVH) parameters (P<.001). On multivariate analysis, anticoagulation therapy (P=.0034), relative volume of rectum receiving 75 Gy (V75; P=.0102), and relative rectal wall V75 (P=.0017) were significant predictors for G2+ RB. Patients treated with investigational protocols had toxicity rates similar to those receiving outcome-tracking protocols. Conclusions: PT was associated with a low rate of GR2+ gastrointestinal toxicity, predominantly transient RB, which was highly correlated with anticoagulation and rectal DVH parameters. Techniques that limit rectal exposure should be used when possible.

  17. Study of Omega-proton correlations in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Han, Yifei; STAR Collaboration

    2015-10-01

    Recently the STAR experiment at RHIC measured Lambda-Lambda correlations from Au+Au collisions at √{sNN} = 200 GeV to search for the H particle (uuddss). The correlation strength indicated that the Lambda-Lambda interaction is weak and is unlikely to be attractive enough to form a bound state. A recent lattice QCD calculation predicted a possible di-baryon bound state with Omega-nucleon. Thus, we will extend the correlation measurements to Omega-proton, which could potentially be a sensitive approach to search for such a state. We will present the Omega-proton correlations based on data collected by STAR in Au+Au collisions at √{sNN} =200 GeV, and discuss the physics implications. for the STAR collaboration.

  18. Study of the proton structure by measurements of polarization transfers in real Compton scattering at Jlab

    SciTech Connect

    Fanelli, Cristiano Fanelli; Cisbani, Evarostp; Hamilton, David; Salme, G.; Wojtsekhowski, Bogdan B.

    2014-03-01

    A preliminary analysis of polarization-transfer data at large scattering angle (70°), obtained in an experiment of real Compton scattering on proton, performed in Hall-C of Jefferson Lab, is presented. It is also discussed the relevance of this kind of experiments for shedding light on the non-perturbative structure of the proton, at low energy, and on the transition from the non-perturbative regime to the perturbative one, that occurs at high energy. Moreover, the possibility to extract Compton form factors and the Generalized Parton Distributions, one of the most promising theoretical tool to determine the total angular momentum contribution of quarks and gluons to nucleon spin, is emphasized.

  19. Proton transfers in a channelrhodopsin-1 studied by Fourier transform infrared (FTIR) difference spectroscopy and site-directed mutagenesis.

    PubMed

    Ogren, John I; Yi, Adrian; Mamaev, Sergey; Li, Hai; Spudich, John L; Rothschild, Kenneth J

    2015-05-15

    Channelrhodopsin-1 from the alga Chlamydomonas augustae (CaChR1) is a low-efficiency light-activated cation channel that exhibits properties useful for optogenetic applications such as a slow light inactivation and a red-shifted visible absorption maximum as compared with the more extensively studied channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2). Previously, both resonance Raman and low-temperature FTIR difference spectroscopy revealed that unlike CrChR2, CaChR1 under our conditions exhibits an almost pure all-trans retinal composition in the unphotolyzed ground state and undergoes an all-trans to 13-cis isomerization during the primary phototransition typical of other microbial rhodopsins such as bacteriorhodopsin (BR). Here, we apply static and rapid-scan FTIR difference spectroscopy along with site-directed mutagenesis to characterize the proton transfer events occurring upon the formation of the long-lived conducting P2 (380) state of CaChR1. Assignment of carboxylic C=O stretch bands indicates that Asp-299 (homolog to Asp-212 in BR) becomes protonated and Asp-169 (homolog to Asp-85 in BR) undergoes a net change in hydrogen bonding relative to the unphotolyzed ground state of CaChR1. These data along with earlier FTIR measurements on the CaChR1 → P1 transition are consistent with a two-step proton relay mechanism that transfers a proton from Glu-169 to Asp-299 during the primary phototransition and from the Schiff base to Glu-169 during P2 (380) formation. The unusual charge neutrality of both Schiff base counterions in the P2 (380) conducting state suggests that these residues may function as part of a cation selective filter in the open channel state of CaChR1 as well as other low-efficiency ChRs. PMID:25802337

  20. Proton Transfers in a Channelrhodopsin-1 Studied by Fourier Transform Infrared (FTIR) Difference Spectroscopy and Site-directed Mutagenesis*

    PubMed Central

    Ogren, John I.; Yi, Adrian; Mamaev, Sergey; Li, Hai; Spudich, John L.; Rothschild, Kenneth J.

    2015-01-01

    Channelrhodopsin-1 from the alga Chlamydomonas augustae (CaChR1) is a low-efficiency light-activated cation channel that exhibits properties useful for optogenetic applications such as a slow light inactivation and a red-shifted visible absorption maximum as compared with the more extensively studied channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2). Previously, both resonance Raman and low-temperature FTIR difference spectroscopy revealed that unlike CrChR2, CaChR1 under our conditions exhibits an almost pure all-trans retinal composition in the unphotolyzed ground state and undergoes an all-trans to 13-cis isomerization during the primary phototransition typical of other microbial rhodopsins such as bacteriorhodopsin (BR). Here, we apply static and rapid-scan FTIR difference spectroscopy along with site-directed mutagenesis to characterize the proton transfer events occurring upon the formation of the long-lived conducting P2380 state of CaChR1. Assignment of carboxylic C=O stretch bands indicates that Asp-299 (homolog to Asp-212 in BR) becomes protonated and Asp-169 (homolog to Asp-85 in BR) undergoes a net change in hydrogen bonding relative to the unphotolyzed ground state of CaChR1. These data along with earlier FTIR measurements on the CaChR1 → P1 transition are consistent with a two-step proton relay mechanism that transfers a proton from Glu-169 to Asp-299 during the primary phototransition and from the Schiff base to Glu-169 during P2380 formation. The unusual charge neutrality of both Schiff base counterions in the P2380 conducting state suggests that these residues may function as part of a cation selective filter in the open channel state of CaChR1 as well as other low-efficiency ChRs. PMID:25802337

  1. Study of proton conductivity of a 2D flexible MOF and a 1D coordination polymer at higher temperature.

    PubMed

    Sanda, Suresh; Biswas, Soumava; Konar, Sanjit

    2015-02-16

    We report the proton conduction properties of a 2D flexible MOF and a 1D coordination polymer having the molecular formulas {[Zn(C10H2O8)0.5(C10S2N2H8)]·5H2O]}n (1) and {[Zn(C10H2O8)0.5(C10S2N2H8)]·2H2O]}n (2), respectively. Compounds 1 and 2 show high conductivity values of 2.55 × 10(-7) and 4.39 × 10(-4) S cm(-1) at 80 °C and 95% RH. The conductivity value of compound 1 is in the range of those for previously reported flexible MOFs, and compound 2 shows the highest proton conductivity among the carboxylate-based 1D CPs. The dimensionality and the internal hydrogen bonding connectivity play a vital role in the resultant conductivity. Variable-temperature experiments of both compounds at high humidity reveal that the conductivity values increase with increasing temperature, whereas the variable humidity studies signify the influence of relative humidity on high-temperature proton conductivity. The time-dependent measurements for both compounds demonstrate their ability to retain conductivity up to 10 h. PMID:25594401

  2. QTES-DFTB dynamics study on the effect of substrate motion on quantum proton transfer in soybean lipoxygenase-1

    NASA Astrophysics Data System (ADS)

    Mazzuca, James; Garashchuk, Sophya; Jakowski, Jacek

    2014-03-01

    It has been shown that the proton transfer in the enzymatic active site of soybean lipoxygenase-1 (SLO-1) occurs largely by a quantum tunneling mechanism. This study examined the role of local substrate vibrations on this proton tunneling reaction. We employ an approximate quantum trajectory (QT) dynamics method with linear quantum force. The electronic structure (ES) was calculated on-the-fly with a density functional tight binding (DFTB) method. This QTES-DFTB method scales linearly with number of trajectories, and the calculation of the quantum force is a small addition to the overall cost of trajectory dynamics. The active site was represented as a 44-atom system. Quantum effects were included only for the transferring proton, and substrate nuclei were treated classically. The effect of substrate vibrations was evaluated by freezing or relaxing the substrate nuclei. Trajectory calculations were performed at several temperatures ranging from 250-350 K, and rate constants were calculated through the quantum mechanical flux operator which depends on time-dependent correlation functions. It was found that the substrate motion reliably increases the rate constants, as well as the P/D kinetic isotope effect, by approximately 10% across all temperatures examined. NSF Grant No. CHE-1056188, APRA-NSF-EPS-0919436, and CHE-1048629, NICS Teragrid/Xsede TG-DMR110037.

  3. 1H NMR study of proton dynamics in the inorganic solid acid Rb3 H( SO4 )2

    NASA Astrophysics Data System (ADS)

    Suzuki, Koh-Ichi; Hayashi, Shigenobu

    2006-01-01

    Proton dynamics in Rb3H(SO4)2 has been studied by means of H1 NMR. The H1 magic-angle-spinning (MAS) NMR spectra were traced at room temperature (RT) at Larmor frequency of 400.13MHz . H1 static NMR spectra were measured at frequencies of 200.13MHz and 400.13MHz in the ranges of 165-513 and 300-513K , respectively. H1 spin-lattice relaxation times, T1 , were measured at 200.13 and 19.65MHz in the ranges of 260-513 and 260-470K , respectively. The H1 MAS NMR spectrum at 294K has an isotropic chemical shift of 16.3ppm from tetramethylsilane, demonstrating very strong hydrogen bonds. In RT phase, a wobbling motion of the O-H axis in one direction at the fast motional limit takes place above 400K , being supported by the H1 static NMR spectral line shapes and by the H1 T1 values. In the high temperature (HT) phase, the sharp H1 static NMR spectra indicate translational proton diffusion. From the analysis of H1 T1 , protons diffuse with the inverse of the frequency factor (τ0) of 9.5×10-13s and the activation energy (Ea) of 25kJmol-1 . These parameters can well explain the macroscopic electric conductivity in HT phase.

  4. Comparison of intensity modulated x-ray therapy and intensity modulated proton therapy for selective subvolume boosting: a phantom study

    NASA Astrophysics Data System (ADS)

    Flynn, R. T.; Barbee, D. L.; Mackie, T. R.; Jeraj, R.

    2007-10-01

    Selective subvolume boosting can theoretically improve tumour control probability while maintaining normal tissue complication probabilities similar to those of uniform dose distributions. In this work the abilities of intensity-modulated x-ray therapy (IMXT) and intensity-modulated proton therapy (IMPT) to deliver boosts to multiple subvolumes of varying size and proximities are compared in a thorough phantom study. IMXT plans were created using the step-and-shoot (IMXT-SAS) and helical tomotherapy (IMXT-HT) methods. IMPT plans were created with the spot scanning (IMPT-SS) and distal gradient tracking (IMPT-DGT) methods. IMPT-DGT is a generalization of the distal edge tracking method designed to reduce the number of proton beam spots required to deliver non-uniform dose distributions relative to IMPT-SS. The IMPT methods were delivered over both 180° and 360° arcs. The IMXT-SAS and IMPT-SS methods optimally satisfied the non-uniform dose prescriptions the least and the most, respectively. The IMPT delivery methods reduced the normal tissue integral dose by a factor of about 2 relative to the IMXT delivery methods, regardless of the delivery arc. The IMPT-DGT method reduced the number of proton beam spots by a factor of about 3 relative to the IMPT-SS method.

  5. Electric field control of proton-transfer molecular switching: molecular dynamics study on salicylidene aniline.

    PubMed

    Jankowska, Joanna; Sadlej, Joanna; Sobolewski, Andrzej L

    2015-06-14

    In this letter, we propose a novel, ultrafast, efficient molecular switch whose switching mechanism involves the electric field-driven intramolecular proton transfer. By means of ab initio quantum chemical calculations and on-the-fly dynamics simulations, we examine the switching performance of an isolated salicylidene aniline molecule and analyze the perspectives of its possible use as an electric field-controlled molecular electronics unit. PMID:25986469

  6. Study and development of sulfated zirconia based proton exchange fuel cell membranes

    NASA Astrophysics Data System (ADS)

    Kemp, Brittany Wilson

    With the increasing consumption of energy, fuel cells are among the most promising alternatives to fossil fuels, provided some technical challenges are overcome. Proton exchange membrane fuel cells (PEMFCs) have been investigated and improvements have been made, but the problem with NafionRTM, the main membrane for PEMFCs, has not been solved. NafionRTM restricts the membranes from operating at higher temperatures, thus preventing them from working in small electronics. The problem is to develop a novel fuel cell membrane that performs comparably to NafionRTM in PEMFCs. The membranes were fabricated by applying sulfated zirconia, via template wetting, to porous alumina membranes. The fabricated membranes showed a proton conductivity of 0.016 S/cm in comparison to the proton conductivity of Nafion RTM (0.05 S/cm). Both formic acid and methanol had a lower crossover flux through the sulfated zirconia membranes (formic acid- 2.89x10 -7 mols/cm2s and methanol-1.78x10-9 mols/cm2s) than through NafionRTM (formic acid-2.03x10 -8 mols/cm2s methanol-2.42x10-6 mols/cm 2s), indicating that a sulfated zirconia PEMFC may serve as a replacement for NafionRTM.

  7. Study of proton conduction in thulium-doped barium zirconates at high temperatures

    NASA Astrophysics Data System (ADS)

    Laidoudi, Mouloud; Abu Talib, Ibrahim; Omar, Ramli

    2000-12-01

    The specimens of BaZr1-xTmxO3-α (x = 0.02, 0.05, 0.10 and 0.15, α = x/2) have been prepared and characterized. The formation of the single perovskite phase in the samples was checked by x-ray diffraction. For the verification of the possible charge carriers in the sintered BaZr1-xTmxO3-α samples, three different electrochemical cell measurements were carried out. The measurements of electromotive force (emf) of hydrogen and steam concentration cells showed that the BaZr1-xTmxO3-α ceramic is a protonic conductor and the measurements of emf of the oxygen concentration cell showed that the BaZr0.90Tm0.10O3-α sample exhibited poor oxide ion conduction. Proton transport number tH was calculated and was found to be dependent on the content, x. The BaZr0.90Tm0.10O3-α sample showed the highest value of proton transport number in the temperature range 500≤T≤900 °C.

  8. Theoretical study of the structure and spectroscopic characteristics of protonated carbon dioxide

    SciTech Connect

    Frisch, M.J.; Schaefer, H.F. III; Binkley, J.S.

    1985-05-23

    Protonated carbon dioxide has been examined theoretically by using geometries optimized at the MP2/6-31G(d) level and energies computed at the MP4/6-311++G(d,p) level. It is concluded that the C/sub s/ O-protonated complex is the only observable form of CO/sub 2/H/sup +/ when it is produced by association of H/sup +/ with CO/sub 2/ and under most other conditions. The enthalpy of protonation of CO/sub 2/ is found to be 130.7 kcal mol/sup -1/ at 298 K. Rotational constants are predicted to be 773.74, 10.79, and 10.65 GHz for CO/sub 2/H/sup +/ and 431.18, 10.17, and 9.94 GHz for CO/sub 2/D/sup +/. Stretching vibrational frequencies are predicted to be 1292, 2330, and 3348 cm/sup -1/ for CO/sub 2/H/sup +/ and 1270, 2316, and 2485 cm/sup -1/ for CO/sub 2/D/sup +/. The O-H (or O-D) stretching mode is expected to produce the most intense fundamental transition in both the infrared and Raman spectra, and the 2330 (2316)cm/sup -1/ C-O stretch is found to be the only other intense mode. 23 references, 3 tables.

  9. Proton and hydride transfers in solution: hybrid QMmm/MM free energy perturbation study

    SciTech Connect

    Ho, L. Lawrence |; Bash, P.A.; Kerell, A.D., Jr

    1996-03-01

    A hybrid quantum and molecular mechanical (QM/MM) free energy perturbation (FEP) method is implemented in the context of molecular dynamics (MD). The semiempirical quantum mechanical (QM) Hamiltonian (Austin Model 1) represents solute molecules, and the molecular mechanical (MM) CHARMM force field describes the water solvent. The QM/MM FEP method is used to calculate the free energy changes in aqueous solution for (1) a proton transfer from methanol to imidazole and (2) a hydride transfer from methoxide to nicotinamide. The QM/MM interaction energies between the solute and solvent arc calibrated to emulate the solute-solvent interaction energies determined at the Hartee-Fock 6-31G(d) level of ab initio theory. The free energy changes for the proton and hydride transfers are calculated to be 15.1 and {minus}6.3 kcal/mol, respectively, which compare favorably with the corresponding experimental values of 12.9 and {minus}7.4 kcal/mol. An estimate of the reliability of the calculations is obtained through the computation of the forward (15.1 and {minus}6.3 kcal/mol) and backward ({minus}14.1 and 9.1 kcal/mol)free energy changes. The reasonable correspondence between these two independent calculations suggests that adequate phase space sampling is obtained along the reaction pathways chosen to transform the proton and hydride systems between their respective reactant and product states.

  10. Comparative study of changes in electrical properties of silicon and silicon carbide upon proton irradiation

    SciTech Connect

    Emtsev, V. V. Ivanov, A. M.; Kozlovskii, V. V.; Lebedev, A. A.; Oganesyan, G. A.; Strokan, N. B.

    2010-05-15

    Rates of carrier removal from the conduction band in n-type FZ-Si and 4H-SiC irradiated with 8- and 15-MeV protons at room temperature are discussed. Calculated rates of formation of primary radiation defects (Frenkel pairs) in these materials are presented and compared with the corresponding experimental values. Protons create defects in collision cascades involving recoil atoms formed in the crystal lattice itself. The results are compared with similar data previously obtained in irradiation of n-type FZ-Si and 4H-SiC with 900-keV electrons, in which case isolated so-called close Frenkel pairs are absolutely dominant among primary radiation defects. It has been found that the E-center model adequately describing the decrease in the electrical conductivity of n-FZ-Si upon electron irradiation is inapplicable to interpretation of experimental data for proton-irradiated materials. It is suggested that a pronounced annealing of 'simple' radiation defects of the type of close Frenkel pairs occurs during irradiation at room temperature.

  11. SU-E-T-267: Proton Pencil Beam Scanning for Mediastinal Lymphoma: 4-Dimensional Feasibility Study

    SciTech Connect

    Zeng, C; Plastaras, J; Tochner, Z; Hill-Kayser, C; Hahn, S; Both, S

    2014-06-01

    Purpose: To assess the feasibility of proton pencil beam scanning (PBS) for the treatment of mediastinal lymphoma. Methods: A group of 6 patients were planned using an anterior field with PBS. Spots with ∼5 mm σ were used for all patients, while large spots (∼10 mm σ) were employed for patients with motion perpendicular to the beam (≥5 mm). We considered volumetric repainting such that, in each fraction, the same field would be delivered twice. Four-dimensional dose was calculated on initial and verification 4-dimensional computed tomography (4D-CT) scans (2—3) based on respiratory trace and beam delivery sequence. This was implemented by binning the spots into separate plans on each 4D-CT phase respectively. Four starting phases were sampled for each painting and 4 energy switching times (0.5 s, 1 s, 3 s, and 5 s) were tested, resulting in 2560 dose distributions for the cohort. Plan robustness was measured for target and critical structures in terms of the percentage difference between delivered dose and planned dose. Results: For 5 of the 6 patients, the ITV (internal target volume) D98% was degraded by <3% (standard deviations ∼ 0.1%) when averaged over the whole course (up to 5% per fraction). Deviations of mean lung dose, heart maximum dose, and cord maximum dose were within 5% of prescribed dose. For one patient with motion perpendicular to the beam (up to 5 mm), the degradation of ITV D98% was 9% over the whole course (12% per fraction), which was mitigated to 1% (3% per fraction) by employing large spots and repainting. No significant difference in coverage was observed for different energy switching times. Conclusion: This feasibility study demonstrates that, for mediastinal lymphoma, the PBS plan robustness can be maintained during delivery when target motion is measured and volumetric repainting and/or large spots are employed. This work was supported by Ion Beam Application.

  12. Pion, Kaon, Proton and Antiproton Production in Proton-Proton Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Blattnig, Steve R.

    2008-01-01

    Inclusive pion, kaon, proton, and antiproton production from proton-proton collisions is studied at a variety of proton energies. Various available parameterizations of Lorentz-invariant differential cross sections as a function of transverse momentum and rapidity are compared with experimental data. The Badhwar and Alper parameterizations are moderately satisfactory for charged pion production. The Badhwar parameterization provides the best fit for charged kaon production. For proton production, the Alper parameterization is best, and for antiproton production the Carey parameterization works best. However, no parameterization is able to fully account for all the data.

  13. Measuring localized viscoelasticity of the vitreous body using intraocular microprobes.

    PubMed

    Pokki, Juho; Ergeneman, Olgaç; Sevim, Semih; Enzmann, Volker; Torun, Hamdi; Nelson, Bradley J

    2015-10-01

    Vitrectomy is a standard ophthalmic procedure to remove the vitreous body from the eye. The biomechanics of the vitreous affects its duration (by changing the removal rate) and the mechanical forces transmitted via the vitreous on the surrounding tissues during the procedure. Biomechanical characterization of the vitreous is essential for optimizing the design and control of instruments that operate within the vitreous for improved precision, safety, and efficacy. The measurements are carried out using a magnetic microprobe inserted into the vitreous, a method known as magnetic microrheology. The location of the probe is tracked by a microscope/camera while magnetic forces are exerted wirelessly by applied magnetic fields. In this work, in vitro artificial vitreous, ex vivo human vitreous and ex vivo porcine vitreous were characterized. In addition, in vivo rabbit measurements were performed using a suturelessly injected probe. Measurements indicate that viscoelasticity parameters of the ex vivo human vitreous are an order of magnitude different from those of the ex vivo porcine vitreous. The in vivo intra-operative measurements show typical viscoelastic behavior of the vitreous with a lower compliance than the ex vivo measurements. The results of the magnetic microrheology measurements were validated with those obtained by a standard atomic force microscopy (AFM) method and in vitro artificial vitreous. This method allows minimally-invasive characterization of localized mechanical properties of the vitreous in vitro, ex vivo, and in vivo. A better understanding of the characteristics of the vitreous can lead to improvements in treatments concerning vitreal manipulation such as vitrectomy. PMID:26238733

  14. 3D dose verification with polymer gel detectors of brain-spine match line for proton pencil beam cranio-spinal: A preliminary study

    NASA Astrophysics Data System (ADS)

    Avery, S.; Cardin, A.; Lin, L.; Kirk, M.; Kassaee, A.; Maryanski, M. J.

    2015-01-01

    This paper is intended as a preliminary study to demonstrate the quality assurance benefits from polymer gel detectors for proton pencil beam cranio-spinal treatments. A stable gel type was selected for protons to suppress the LET dependence at the end of the Bragg peak. The depth dose distributions in the gels were examined with regard of its dose dependences and compared to baseline measurements. The preliminary experimental results indicate polymer gel detectors may be able to verify dose in three dimensions along match line for proton therapy treatments.

  15. PROTON MICROSCOPY AT FAIR

    SciTech Connect

    Merrill, F. E.; Mariam, F. G.; Golubev, A. A.; Turtikov, V. I.; Varentsov, D.

    2009-12-28

    Proton radiography was invented in the 1990's at Los Alamos National Laboratory (LANL) as a diagnostic to study dynamic material properties under extreme pressures, strain and strain rate. Since this time hundreds of dynamic proton radiography experiments have been performed at LANL and a facility has been commissioned at the Institute for Theoretical and Experimental Physics (ITEP) in Russia for similar applications in dynamic material studies. Recently an international effort has investigated a new proton radiography capability for the study of dynamic material properties at the Facility for Anti-proton and Ion Research (FAIR) located in Darmstadt, Germany. This new Proton microscope for FAIR(PRIOR) will provide radiographic imaging of dynamic systems with unprecedented spatial, temporal and density resolution, resulting in a window for understanding dynamic material properties at new length scales. It is also proposed to install the PRIOR system at the GSI Helmholtzzentrum fuer Schwerionenforschung before installation at FAIR for dynamic experiments with different drivers including high explosives, pulsed power and lasers. The design of the proton microscope and expected radiographic performance is presented.

  16. Generation of proton aurora by magnetosonic waves

    PubMed Central

    Xiao, Fuliang; Zong, Qiugang; Wang, Yongfu; He, Zhaoguo; Su, Zhenpeng; Yang, Chang; Zhou, Qinghua

    2014-01-01

    Earth's proton aurora occurs over a broad MLT region and is produced by the precipitation of low-energy (2–10 keV) plasmasheet protons. Proton precipitation can alter chemical compositions of the atmosphere, linking solar activity with global climate variability. Previous studies proposed that electromagnetic ion cyclotron waves can resonate with protons, producing proton scattering precipitation. A long-outstanding question still remains whether there is another mechanism responsible for the proton aurora. Here, by performing satellite data analysis and diffusion equation calculations, we show that fast magnetosonic waves can produce trapped proton scattering that yields proton aurora. This provides a new insight into the mechanism of proton aurora. Furthermore, a ray-tracing study demonstrates that magnetosonic wave propagates over a broad MLT region, consistent with the global distribution of proton aurora. PMID:24898626

  17. The study of the neutral pion production in proton-proton collisions at beam momenta 1581 and 1683 MeV/c

    NASA Astrophysics Data System (ADS)

    Sarantsev, V. V.; Ermakov, K. N.; Medvedev, V. I.; Oposhnyan, T. S.; Rogachevsky, O. V.; Sherman, S. G.

    The detailed investigation of the reaction pp -> ppπ 0 has been carried out at two incident proton momenta. Momentum, angular and effective-mass distributions were analyzed in the framework of the one-pion exchange model. Taking into account only the P33-wave in the pole diagrams allows one to obtain a good agreement with experimental data on differential distributions. At the same time the predictions for total cross-sections are much lower than the experimental data.

  18. Joint neutron crystallographic and NMR solution studies of Tyr residue ionization and hydrogen bonding: Implications for enzyme-mediated proton transfer

    DOE PAGESBeta

    Michalczyk, Ryszard; Unkefer, Clifford J.; Bacik, John -Paul; Schrader, Tobias E.; Ostermann, Andreas; Kovalevsky, Andrey Y.; McKenna, Robert; Fisher, Suzanne Zoe

    2015-05-05

    Proton transfer is a fundamental mechanism at the core of many enzyme-catalyzed reactions. It is also exquisitely sensitive to a number of factors, including pH, electrostatics, proper active-site geometry, and chemistry. Carbonic anhydrase has evolved a fast and efficient way to conduct protons through a combination of hydrophilic amino acid side chains that coordinate a highly ordered H-bonded water network. This study uses a powerful approach, combining NMR solution studies with neutron protein crystallography, to determine the effect of pH and divalent cations on key residues involved in proton transfer in human carbonic anhydrase. Lastly, the results have broad implicationsmore » for our understanding of proton transfer and how subtle changes in ionization and H-bonding interactions can modulate enzyme catalysis.« less

  19. Joint neutron crystallographic and NMR solution studies of Tyr residue ionization and hydrogen bonding: Implications for enzyme-mediated proton transfer

    SciTech Connect

    Michalczyk, Ryszard; Unkefer, Clifford J.; Bacik, John -Paul; Schrader, Tobias E.; Ostermann, Andreas; Kovalevsky, Andrey Y.; McKenna, Robert; Fisher, Suzanne Zoe

    2015-05-05

    Proton transfer is a fundamental mechanism at the core of many enzyme-catalyzed reactions. It is also exquisitely sensitive to a number of factors, including pH, electrostatics, proper active-site geometry, and chemistry. Carbonic anhydrase has evolved a fast and efficient way to conduct protons through a combination of hydrophilic amino acid side chains that coordinate a highly ordered H-bonded water network. This study uses a powerful approach, combining NMR solution studies with neutron protein crystallography, to determine the effect of pH and divalent cations on key residues involved in proton transfer in human carbonic anhydrase. Lastly, the results have broad implications for our understanding of proton transfer and how subtle changes in ionization and H-bonding interactions can modulate enzyme catalysis.

  20. Laser-driven plasma jets propagating in an ambient gas studied with optical and proton diagnostics

    NASA Astrophysics Data System (ADS)

    Gregory, C. D.; Loupias, B.; Waugh, J.; Dono, S.; Bouquet, S.; Falize, E.; Kuramitsu, Y.; Michaut, C.; Nazarov, W.; Pikuz, S. A.; Sakawa, Y.; Woolsey, N. C.; Koenig, M.

    2010-05-01

    The results of an experiment to propagate laser-generated plasma jets into an ambient medium are presented. The jets are generated via laser irradiation of a foam-filled cone target, the results and characterization of which have been reported previously [Loupias et al., Phys. Rev. Lett. 99, 265001 (2007)] for propagation in vacuum. The introduction of an ambient medium of argon at varying density is seen to result in the formation of a shock wave, and the shock front displays perturbations that appear to grow with time. The system is diagnosed with the aid of proton radiography, imaging the perturbed structure in the dense parts of the shock with high resolution.

  1. Construction of low current 30 keV proton accelerator for detection efficiency studies

    NASA Astrophysics Data System (ADS)

    Salas Bacci, Americo; Baessler, Stefan; Ross, Aaron; Roane, Nicholas; Whitaker, C. J.

    2013-10-01

    We have constructed a small ion source and proton accelerator at UVA. This accelerator is needed for the characterization of the detection efficiency of a large area, thick, 127-hexagonal segmented Silicon detector for the neutron beta decay ``Nab'' experiment that will be carried out at SNS, Oak Ridge National Laboratory in search of physics beyond the standard model. We will present the design, simulations, operation, and detection of 30 keV H+ and H2+, as well as our efforts to stabilize and correlate both ion currents.

  2. Proton NMR studies of the electronic structure of ZrH/sub x/

    NASA Technical Reports Server (NTRS)

    Attalla, A.; Bowman, R. C., Jr.; Craft, B. D.; Venturini, E. L.; Rhim, W. K.

    1982-01-01

    The proton spin lattice relaxation times and Knight shifts were measured in f.c.c. (delta-phase) and f.c.t. (epsilon-phase) ZrH/sub x/ for 1.5 or = to x or = to 2.0. Both parameters indicate that N(E/sub F/) is very dependent upon hydrogen content with a maximum occurring at ZrH1 83. This behavior is ascribed to modifications in N(E/sub F/) through a fcc/fct distortion in ZrH/sub x/ associated with a Jahn-Teller effect.

  3. Study of proton and neutron activation of metal samples in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Laird, C. E.

    1984-01-01

    Progress in the following activities has been made: the analysis of the gamma ray spectra taken from samples flown in Spacelab 2; the search for and review of neutron and proton activation cross sections needed to analyze the results of the Long Duration Exposure Facility (LDEF) activation measurements; the consideration given to data analysis of the LDEF and Spacelab 2 samples; the plan to measure relevant cross sections with nuclear accelerator measurements; and the preparation of an extended gamma ray calibration sources continues through planning and direct measurement of gamma ray efficiency for a Ge(Li) as a function of position along the surface of the detector housing.

  4. 8He cluster structure studied by recoil proton tagged knockout reaction

    NASA Astrophysics Data System (ADS)

    Ye, Y.; Cao, Z.; Xiao, J.; Jiang, D.; Zheng, T.; Hua, H.; Ge, Y.; Li, X.; Lou, J.; Li, Q.; Lv, L.; Qiao, R.; You, H.; Chen, R.; Sakurai, H.; Otsu, H.; Li, Z.; Nishimura, M.; Sakaguchi, S.; Baba, H.; Togano, Y.; Yoneda, K.; Li, C.; Wang, S.; Wang, H.; Li, K.; Nakayama, Y.; Kondo, Y.; Deguchi, S.; Sato, Y.; Tshoo, K.

    2013-04-01

    Knockout reaction experiment for 8He at 82.3 MeV/u on Hydrogen target was carried out at the RIPS beam line in RIKEN. Recoil protons were detected in coincidence with the forward moving core fragments and neutrons. The quasi-free knockout mechanism is identified through the polar angle correlation and checked by various kinematics conditions. The absolute differential cross sections for 6He core cluster are obtained and compared with the simple Glauber model calculations. The extracted spectroscopic factor is close to unity and a shrinking of the cluster size is evidenced.

  5. Shielding of manned space stations against Van Allen Belt protons: a preliminary scoping study

    SciTech Connect

    Santoro, R.T.; Alsmiller, R.G. Jr.; Barnes, J.M.; Corbin, J.M.

    1986-09-01

    Calculated results are presented to aid in the design of the shielding required to protect astronauts in a space station that is orbiting through the Van Allen proton belt. The geometry considered - a spherical shell shield with a spherical tissue phantom at its center - is only a very approximate representation of an actual space station, but this simple geometry makes it possible to consider a wide range of possible shield materials. Both homogeneous and laminated shields are considered. Also, an approximation procedure - the equivalent thickness approximation - that allows dose rates to be estimated for any shield material or materials from the dose rates for an aluminum shield is presented and discussed.

  6. Far-infrared spectral studies of phase changes in water ice induced by proton irradiation

    NASA Technical Reports Server (NTRS)

    Moore, Marla H.; Hudson, Reggie L.

    1992-01-01

    Changes in the FIR spectrum of crystalline and amorphous water ice as a function of temperature are reported. The dramatic differences between the spectra of these ices in the FIR are used to examine the effect of proton irradiation on the stability of the crystalline and amorphous ice phases from 13 to 77 K. In particular, the spectra near 13 K show interconversion between the amorphous and crystalline ice phases beginning at doses near 2 eV/molecule and continuing cyclically with increased dose. The results are used to estimate the stability of irradiated ices in astronomical environments.

  7. EXPERIMENTAL STUDY OF PROTON-BEAM HALO INDUCED BY BEAM MISMATCH IN LEDA.

    SciTech Connect

    Wangler, Thomas P.,; Allen, C. K.; Colestock, P. L. ,; Chan, K. D.; Crandall, K. R.; Garnett, R. W.; Gilpatrick, J. D.; Lysenko, W. P.; Qiang, J.; Schneider, J. D.; Sheffield, R. L.; Smith, H. V.; Schulze, M. E.

    2001-01-01

    We report measurements of transverse beam halo in mismatched proton beams in a 52-quadrupole FODO transport channel following the 6.7-MeV LEDA RFQ. Beam profiles in both transverse planes are measured using beam-profile diagnostic devices that consist of a movable carbon filament for measurement of the dense beam core, and scraper plates for measurement of the halo. The gradients of the first four quadrupoles can be independently adjusted to mismatch the RFQ output beam into the beam-transport channel. The properties of the measured mismatched beam profiles in the transport channel will be compared with predictions from multiparticle beam-dynamics simulations.

  8. Multistate empirical valence bond study of temperature and confinement effects on proton transfer in water inside hydrophobic nanochannels.

    PubMed

    Tahat, Amani; Martí, Jordi

    2016-07-01

    Microscopic characteristics of an aqueous excess proton in a wide range of thermodynamic states, from low density amorphous ices (down to 100 K) to high temperature liquids under the critical point (up to 600 K), placed inside hydrophobic graphene slabs at the nanometric scale (with interplate distances between 3.1 and 0.7 nm wide) have been analyzed by means of molecular dynamics simulations. Water-proton and carbon-proton forces were modeled with a multistate empirical valence bond method. Densities between 0.07 and 0.02 Å(-3) have been considered. As a general trend, we observed a competition between effects of confinement and temperature on structure and dynamical properties of the lone proton. Confinement has strong influence on the local structure of the proton, whereas the main effect of temperature on proton properties is observed on its dynamics, with significant variation of proton transfer rates, proton diffusion coefficients, and characteristic frequencies of vibrational motions. Proton transfer is an activated process with energy barriers between 1 and 10 kJ/mol for both proton transfer and diffusion, depending of the temperature range considered and also on the interplate distance. Arrhenius-like behavior of the transfer rates and of proton diffusion are clearly observed for states above 100 K. Spectral densities of proton species indicated that in all states Zundel-like and Eigen-like complexes survive at some extent. © 2016 Wiley Periodicals, Inc. PMID:27189810

  9. Electron microprobe and X-ray microfluorescence analyses of copper binding to active and inactivated cells of Mucor rouxii

    SciTech Connect

    Cano-Aguilera, I.; Gardea-Torresdey, J.L.; Pingitore, N.E. Jr.; Webb, R.

    1997-12-31

    Electron microprobe and x-ray microfluorescence spectroscopies have been used to study copper binding to active and inactivated Mucor rouxii copper-sensitive and copper-tolerant cells. A better understanding of metal resistance may help in the application of fungal biomass for the treatment of metal-contaminated water, and also in enrichment or recycling of valuable metals. After repeated culturing in progressively higher concentrations of copper sulfate, a copper-tolerant Mucor rouxii strain was obtained. The copper-tolerant strain differed from the sensitive parental strain in both shape and size. Copper binding studies using a laboratory batch technique revealed that the copper-tolerant strain cultured at higher copper levels bound large amounts of this metal. Electron microprobe and x-ray microfluorescence analyses showed that the copper characteristic x-ray signal on the cell surface of the copper-tolerant strain after copper binding was higher than the copper signal in sensitive cells. The copper signal in cross sections of the copper-tolerant cells also showed a statistically significant correlation with the sulfur signal but no correlation with the phosphorus signal. These results suggest that there are several mechanisms for metal detoxification inside and outside of the Mucor rouxii cells and that copper may be binding to sulfur-containing groups.

  10. Proton Transfer Studied Using a Combined Ab Initio Reactive Potential Energy Surface with Quantum Path Integral Methodology

    PubMed Central

    Wong, Kim F.; Sonnenberg, Jason L.; Paesani, Francesco; Yamamoto, Takeshi; Vaníček, Jiří; Zhang, Wei; Schlegel, H. Bernhard; Case, David A.; Cheatham, Thomas E.; Miller, William H.; Voth, Gregory A.

    2010-01-01

    The rates of intramolecular proton transfer are calculated on a full-dimensional reactive electronic potential energy surface that incorporates high level ab initio calculations along the reaction path and by using classical Transition State theory, Path-Integral Quantum Transition State Theory, and the Quantum Instanton approach. The specific example problem studied is malonaldehyde. Estimates of the kinetic isotope effect using the latter two methods are found to be in reasonable agreement with each other. Improvements and extensions of this practical, yet chemically accurate framework for the calculations of quantized, reactive dynamics are also discussed. PMID:21116485

  11. Unfolding the Quantum Nature of Proton Bound Symmetric Dimers of (MeOH)2H+ and (Me2O)2H+: a Theoretical Study

    NASA Astrophysics Data System (ADS)

    Tan, Jake Acedera; Kuo, Jer-Lai

    2014-06-01

    A proton under a tug of war between two competing Lewis bases is a common motif in biological systems and proton transfer processes. Over the past decades, model compounds for such motifs can be prepared by delicate stoichiometric control of salt solutions. Unfortunately, condensed phase studies, which aims to identify the key vibrational signatures are complicated to analyze. As a result, gas-phase studies do provide promising insights on the behavior of the shared proton. This study attempts to understand the quantum nature of the shared proton under theoretical paradigms. Proton bound symmetric dimers of (MeOH)2H+ and (Me2O)2H+ are chosen as the model compounds. The simulation is performed using Density Functional Theory (DFT) at the B3LYP level with 6-311+G(d,p) as the basis set. It was found out that stretching mode of shared proton couples with several other normal modes and its corresponding oscillator strength do distribute to other normal modes. J.R. Roscioli, L.R. McCunn and M.A. Johnson. Science 2007, 316, 249 T.E. DeCoursey. Physiol. Rev., 2003, 83, 475 E.S. Stoyanov. Psys. Chem. Phys., 2000,2,1137

  12. A comprehensive study of isomerization and protonation reactions in the photocycle of the photoactive yellow protein.

    PubMed

    Wei, Lili; Wang, Hongjuan; Chen, Xuebo; Fang, Weihai; Wang, Haobin

    2014-12-14

    The light-activated photoactive yellow protein (PYP) chromophore uses a series of reactions to trigger photo-motility and biological responses, and generate a wide range of structural signals. To provide a comprehensive mechanism of the overall process at the atomic level, we apply a CASPT2//CASSCF/AMBER QM/MM protocol to investigate the relaxation pathways for a variety of possible isomerization and proton transfer reactions upon photoexcitation of the wild-type PYP. The nonadiabatic relay through an S1/S0 conical intersection [CI(S1/S0)] is found to play a decisive major role in bifurcating the excited state relaxation into a complete and short photocycle. Two major and one minor deactivation channels were found starting from the CI(S1/S0)-like intermediate IT, producing the cis isomers pR1, ICP, and ICT through "hula twist", "bicycle pedal" and one-bond flip isomerization reactions. The overall photocycle can be achieved by competitive parallel/sequential reactions, in which the ground state recovery is controlled by a series of slow volume-conserving bicycle pedal/hula twist and one-bond flip isomerization reactions, as well as fast protonation-deprotonation processes and the hydrophobic-hydrophilic state transformation. PMID:25195953

  13. Ciliary body and choroidal melanomas treated by proton beam irradiation. Histopathologic study of eyes

    SciTech Connect

    Seddon, J.M.; Gragoudas, E.S.; Albert, D.M.

    1983-09-01

    Proton beam irradiation resulted in clinical and/or histopathological regression of large ciliary body and choroidal melanomas in three eyes. Enucleations were performed 6 1/2 weeks, five months, and 11 months after irradiation for angle-closure glaucoma from total retinal detachment, increase in retinal detachment, and neovascular glaucoma, respectively. A direct relationship was found between the length of the interval from irradiation to enucleation and the degree of histologic changes. Vascular changes in the tumors included endothelial cell swelling and decreased lumen size, basement membrane thickening, collapse of sinusoidal vessels, and thrombosis of vessels. Although apparently unaltered tumor cells remained, degenerative changes occurred in some melanoma cells, including lipid vacuoles in cytoplasm, pyknotic nuclei, and balloon cell formation. Patchy areas of necrosis and proteinaceous exudate were present. Pigment-laden macrophages were found near tumor vessels and all had a substantial chronic inflammatory infiltrate. The effect of proton beam irradiation on tumor vessels probably plays an important role in uveal melanoma regression.

  14. Studies of proton-irradiated SO2 at low temperatures Implications for Io

    NASA Astrophysics Data System (ADS)

    Moore, M. H.

    1984-07-01

    The infrared absorption spectrum from 3.3 to 27 microns of SO2 ice films has been measured at 20 and 88 K before and after 1-MeV proton irradiation. The radiation flux was chosen to simulate the estimated flux of Jovian magnetospheric 1-MeV protons incident on Io. After irradiation, SO3 is identified as the dominant molecule synthesized in the SO2 ice. This is also the case after irradiation of composite samples of SO2 with sulfur or disulfites. Darkening was observed in irradiated SO2 ice and in irradiated S8 pellets. Photometric and spectral measurements of the thermoluminescence of irradiated SO2 have been made during warming. The spectrum appears as a broad band with a maximum at 4450 A. Analysis of the luminescence data suggests that at Ionian temperatures irradiated SO2 ice would not be a dominant contributor to posteclipse brightening phenomena. After warming to room temperature, a form of SO3 remains along with a sulfate and S8. Based on these experiments, it is reasonable to propose that small amounts of SO3 may exist on the surface of Io as a result of irradiation synthesis in SO2 frosts.

  15. A beam optics study of the biomedical beam line at a proton therapy facility

    NASA Astrophysics Data System (ADS)

    Yun, Chong Cheoul; Kim, Jong-Won

    2007-10-01

    A biomedical beam line has been designed for the experimental area of a proton therapy facility to deliver mm to sub-mm size beams in the energy range of 20-50 MeV using the TRANSPORT/TURTLE beam optics codes and a newly-written program. The proton therapy facility is equipped with a 230 MeV fixed-energy cyclotron and an energy selection system based on a degrader and slits, so that beam currents available for therapy decrease at lower energies in the therapeutic beam energy range of 70-230 MeV. The new beam line system is composed of an energy-degrader, two slits, and three quadrupole magnets. The minimum beam sizes achievable at the focal point are estimated for the two energies of 50 and 20 MeV. The focused FWHM beam size is approximately 0.3 mm with an expected beam current of 20 pA when the beam energy is reduced to 50 MeV from 100 MeV, and roughly 0.8 mm with a current of 10 pA for a 20 MeV beam.

  16. Studies of proton-irradiated SO2 at low temperatures Implications for Io

    NASA Technical Reports Server (NTRS)

    Moore, M. H.

    1984-01-01

    The infrared absorption spectrum from 3.3 to 27 microns of SO2 ice films has been measured at 20 and 88 K before and after 1-MeV proton irradiation. The radiation flux was chosen to simulate the estimated flux of Jovian magnetospheric 1-MeV protons incident on Io. After irradiation, SO3 is identified as the dominant molecule synthesized in the SO2 ice. This is also the case after irradiation of composite samples of SO2 with sulfur or disulfites. Darkening was observed in irradiated SO2 ice and in irradiated S8 pellets. Photometric and spectral measurements of the thermoluminescence of irradiated SO2 have been made during warming. The spectrum appears as a broad band with a maximum at 4450 A. Analysis of the luminescence data suggests that at Ionian temperatures irradiated SO2 ice would not be a dominant contributor to posteclipse brightening phenomena. After warming to room temperature, a form of SO3 remains along with a sulfate and S8. Based on these experiments, it is reasonable to propose that small amounts of SO3 may exist on the surface of Io as a result of irradiation synthesis in SO2 frosts.

  17. Interactions between Nafion resin and protonated dodecylamine modified montmorillonite: a solid state NMR study.

    PubMed

    Zhang, Limin; Xu, Jun; Hou, Guangjin; Tang, Huiru; Deng, Feng

    2007-07-01

    A series of nanocomposites have been prepared from perfluorosulfonylfluoride copolymer resin (Nafion) and layered montmorillonite (MMT) modified with protonated dodecylamine by conventional sol-gel intercalation. The structure of these nanocomposite materials have been characterized using FT-IR, elemental analysis, XRD and solid state NMR techniques, including 19F magic-angle spinning (MAS) NMR, 19F NMR relaxation time measurements, 29Si MAS, 1H MAS, 1H-13C cross-polarization magic-angle spinning (CPMAS), and 1H-13C heteronuclear correlation (HETCOR) 2D NMR. The results showed that thermal stability of Nafion was improved moderately by the addition of dodecylamine modified MMT without intercalation. FT-IR and 29Si MAS NMR results indicated that dodecylamine modification did not result in obvious changes in the MMT lattice structure. The XRD results showed that the protonated dodecylamine has been embedded and intercalated into the MMT interlayers, whereas Nafion was not. Elemental analysis results also suggested that some dodecylamine was adsorbed on the surface of MMT. 1H-13C HETCOR 2D NMR experiment clearly indicated that strong electrostatic interactions were present between the NH+3 group of dodecylamine and the fluorine-containing groups (CF3, OCF2, and SCF2) of Nafion resin. Such electrostatic interactions are probably the major contributors for the improved thermal stability of the resultant composite materials. PMID:17382953

  18. Effects of vibrational excitation on multidimensional tunneling: General study and proton tunneling in tropolone

    NASA Astrophysics Data System (ADS)

    Takada, Shoji; Nakamura, Hiroki

    1995-03-01

    Tunneling energy splittings of vibrationally excited states are calculated quantum mechanically using several models of two-dimensional symmetric double well potentials. Various effects of vibrational excitation on tunneling are found to appear, depending on the topography of potential energy surface; the symmetry of the mode coupling plays an essential role. Especially, oscillation of tunneling splitting with respect to vibrational quantum number can occur and is interpreted by a clear physical picture based on the semiclassical theory formulated recently [Takada and Nakamura, J. Chem. Phys. 100, 98 (1994)]. The mixed tunneling in the C region found there allows the wave functions to have nodal lines in classically inaccessible region and can cause the suppression of the tunneling. The above analysis is followed by the interpretation of recent experiments of proton tunneling in tropolone. Ab initio molecular orbital calculations are carried out for the electronically ground state. A simple three-dimensional model potential is constructed and employed to analyze the proton tunneling dynamics. Some of the experimentally observed intriguing features can be explained by the typical mechanisms discussed above.

  19. DFT Study on Enzyme Turnover Including Proton and Electron Transfers of Copper-Containing Nitrite Reductase.

    PubMed

    Lintuluoto, Masami; Lintuluoto, Juha M

    2016-08-23

    The reaction mechanism of copper-containing nitrite reductase (CuNiR) has been proposed to include two important events, an intramolecular electron transfer and a proton transfer. The two events have been suggested to be coupled, but the order of these events is currently under debate. We investigated the entire enzyme reaction mechanism of nitrite reduction at the T2 Cu site in thermophilic Geobacillus CuNiR from Geobacillus thermodenitrificans NG80-2 (GtNiR) using density functional theory calculations. We found significant conformational changes of His ligands coordinated to the T2 Cu site upon nitrite binding during the catalytic reaction. The reduction potentials and pKa values calculated for the relevant protonation and reduction states show two possible routes, A and B. Reduction of the T2 Cu site in the resting state is followed by endothermic nitrite binding in route A, while exothermic nitrite binding occurs prior to reduction of the T2 Cu site in route B. We concluded that our results support the random-sequential mechanism rather than the ordered mechanism. PMID:27455866

  20. Skeletal muscle fiber analysis by atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionization mass spectrometric imaging at high mass and high spatial resolution.

    PubMed

    Tsai, Yu-Hsuan; Bhandari, Dhaka Ram; Garrett, Timothy J; Carter, Christy S; Spengler, Bernhard; Yost, Richard A

    2016-06-01

    Skeletal muscles are composed of heterogeneous muscle fibers with various fiber types. These fibers can be classified into different classes based on their different characteristics. MALDI mass spectrometric imaging (MSI) has been applied to study and visualize different metabolomics profiles of different fiber types. Here, skeletal muscles were analyzed by atmospheric pressure scanning microprobe MALDI-MSI at high spatial and high mass resolution. PMID:27198224