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  • 1
    Electronic Resource
    Electronic Resource
    A novel derivatization method for peptides to increase sensitivity and backbone fragmentation in liquid secondary-ion mass spectra (1992)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 747-752 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Derivatization is used to increase both negative-ion sensitivity and positive-ion sequence information in the liquid secondary-ion mass spectra (LSIMS) of a series of peptides. The derivatization method involves acylation with pentafluorobenzyl fluoride in a single-step reaction, and the reaction mixture is applied directly to the probe tip for analysis. Acylation takes place at the unprotexted N-terminus, tyrosine, and lysine. The derivatives exhibit increased signal-to-noise ration for [M—H]- ions, especially where there is not already an acidic amino acid residue in the peptide. In positive-ion LSIMS, the N-terminal group acts to retain the charge at the N-terminus, simplifying the fragmentation by producing N-terminal fragment ions. It also increases positive-ion fragmentation, sometimes very dramatically, making sequence determination more straightforward. The simplicity of the process, together with the enhancements it provides, make3 this a generally useful method for obtaining peptide structural information.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290061207
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  • 2
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    Some Field Observations Bearing on the Origin of the Morrison "Gastroliths" (1942)
    American Association for the Advancement of Science
    Details
    Publication Date: 1942-01-02
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science
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    PAPER CURRENT
  • 3
    Electronic Resource
    Electronic Resource
    Recent experiments with liquid gallium cooling of crystal diffraction optics (abstract)a) : Proceedings of the 4th International Conference on Synchrotron Radiation Instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 485-485 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The x-ray beams for the next generation of synchrotrons will contain much more power (1–10 kW) than is available at present day facilities. Cooling the first optical components in these beam lines will require the best cooling technology that one can bring to bear. Argonne continues to pioneer the use of liquid metals as the cooling fluid and has adopted liquid gallium as the liquid metal of choice. Its low melting point, 29.7 °C and its very low vapor pressure make it an easy fluid to handle and its high thermal conductivity and heat capacity make it an excellent cooling fluid. A series of experiments were performed during April 1991 with the wiggler beam at the F2 station of the CHESS facility at Cornell to investigate the cooling of large areas of high power. Two types of cooling crystal geometries were tested, one where the cooling channels were core-drilled just below the surface of the crystal and a second where slots were cut into the crystal just below the surface with a diamond saw. Both crystals performed well with beam powers up to 1050 W and power densities of up to 14.5 W/mm2 at normal incidence.An infrared camera was used to measure the variation in the temperature of the top layer of the silicon crystals. For the core-drilled crystal the peak temperature measured at the center of the beam at a power density of 12.3 W/mm2 was 15 °C hotter than the crystal surface outside of the beam with a flow of liquid gallium of 2 gpm (gallons per minute) and was 10 °C with a flow of 4 gpm. The maximum distortion of the crystal surface distortion of the core drilled crystal was about ±2.0 arcsec for the 2 gpm case with a maximum power density of 10.9 W/mm2 and about 5% of the expected beam intensity was lost at peak power of 14.5 W/mm2. For the slotted crystal the peak temperature difference for a peak power of 10.9 W/mm2 was 3.5 and 2.0 °C for liquid gallium flows of 1 and 2 gpm, respectively. No intensity loss was measured for the maximum power density of 14.5 W/mm2. The fact that the peak temperature differences on the surface of both crystals was decreasing with increased flow of liquid gallium suggests that even higher power densities can be accommodated with higher flows of liquid gallium. This work is supported by the Department of Energy, BES-Materials Sciences, under Contract W-31-109-Eng-38.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142738
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  • 4
    Electronic Resource
    Electronic Resource
    Low-temperature formation of epitaxial Tl2Ca2Ba2Cu3O10 thin films in reduced O2 pressure (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 772-774 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial Tl2Ca2Ba2Cu3O10 films on (100) LaAlO3 are prepared by post-annealing 2Tl:2Ca:2Ba:3Cu precursor films at 830–860 °C in (approximately-equal-to)0.03–0.15 atm of O2. These films (0.2–1.1 μm thickness) are smooth and shiny to the eye, and have a sharp zero resistance and onset diamagnetic transition temperature of 117–121 K. Transport critical current densities of 1.6×106 A/cm2 at 77 K and (approximately-equal-to)105 A/cm2 at 100 K are obtained for a 0.38-μm-thick film in magnetic fields up to 100 Oe. Strong flux pinning at low temperatures is inferred from the weak-field dependence of the critical current density calculated from magnetic hysteresis loops. At 5 K, the best film has a magnetic critical current density of 9×106 A/cm2 in zero field, decreasing gradually to 1.5×106 A/cm2 in a 5-T field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106515
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  • 5
    Electronic Resource
    Electronic Resource
    Narrow-linewidth frequency stabilized AlxGa1−xAs/GaAs laser (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1544-1546 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Velocity-selective magnetic optical activity in Rb vapor was used to simultaneously narrow the linewidth (500 kHz) and stabilize the frequency of an AlxGa1−xAs/GaAs laser. The frequency stability was determined by heterodyning two similar lasers and measuring their relative stability. The square root of the Allan variance, a standard figure of merit, was σy(τ)=4.9×10−12 for an averaging time of 200 s. This corresponds to a standard deviation of the beat frequency fluctuations of 1.9 kHz.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107245
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of oxygen pressure on Tl2Ca2Ba2Cu3O10±δ formation (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 2150-2152 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the formation of Tl2Ca2Ba2Cu3O10±δ as a function of oxygen pressure and temperature. Our results explain some previous difficulties in forming single-phase Tl2Ca2Ba2Cu3O10±δ and suggest new routes for making bulk and thin-film Tl-Ca-Ba-Cu-O superconductors. In particular, we find that the temperature needed to form Tl2Ca2Ba2Cu3O10±δ can be greatly reduced by using low oxygen pressures during synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107066
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  • 7
    Electronic Resource
    Electronic Resource
    Characteristics of GaAs, AlGaAs, and InGaAs materials grown by metalorganic chemical vapor deposition using an on-demand hydride gas generator (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1483-1485 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report results on the properties of GaAs, AlGaAs, and InGaAs materials grown using a new, on-demand hydride gas generator. Low pressure arsine gas is generated from an arsenic containing precursor (KAsH2) by the controlled addition of water as a chemical activator. Both generated and bottled arsine are used to grow GaAs, AlGaAs, and InGaAs structures using atmospheric pressure metalorganic chemical vapor deposition. Using generated arsine, GaAs layers with background carrier concentrations of less than n=3×1013 cm−3 were produced across a growth temperature range of 625–725 °C using a V/III ratio of 30. InGaAs grown at 640 °C with V/III=30 exhibits a background carrier concentration of n=2.5×1014 cm−3 and mobility values of μ300 K=11 350 cm2/V s and μ77 K=71 200 cm2/V s. Photoluminescence measurements show highly resolved exciton spectra using either generated or bottled arsine with donor-bound exciton linewidths as narrow as 0.16 meV full width at half-maximum. Broad area GaAs/AlGaAs laser devices exhibit threshold current densities as low as 195 A/cm2. The results obtained from bulk layer, quantum well structure, and broad area laser device characterization indicate that the quality of materials produced using generated arsine is equivalent or superior to that of materials produced using a high quality bottled arsine source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107278
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  • 8
    Electronic Resource
    Electronic Resource
    Three-dimensional hybrid gyrokinetic-magnetohydrodynamics simulation (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 2033-2037 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A three-dimensional (3-D) hybrid gyrokinetic-MHD (magnetohydrodynamic) simulation scheme is presented. To the 3-D toroidal MHD code, MH3D-K the energetic particle component is added as gyrokinetic particles. The resulting code, mh3d-k, is used to study the nonlinear behavior of energetic particle effects in tokamaks, such as the energetic particle stabilization of sawteeth, fishbone oscillations, and alpha-particle-driven toroidal Alfvén eigenmode (TAE) modes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860011
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  • 9
    Electronic Resource
    Electronic Resource
    Recent experiments with liquid gallium cooling of crystal diffraction opticsa) (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1746-1754 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The x-ray beams for the next generation of synchrotrons will contain much more power (1–10 kW) than is available at present day facilities. Cooling the first optical components in these beam lines will require the best cooling technology that one can bring to bear. Argonne continues to pioneer the use of liquid metals as the cooling fluid and has adopted liquid gallium as the liquid metal of choice. Its low melting point, 29.7 °C and its very low vapor pressure make it an easy fluid to handle and its high thermal conductivity and heat capacity make it an excellent cooling fluid. A series of experiments were performed during April 1991 with the wiggler beam at the F2 station of the CHESS facility at Cornell to investigate the cooling of large areas of high power. Two types of cooling crystal geometries were tested. One where the cooling channels were core drilled just below the surface of the crystal and a second where slots were cut into the crystal just below the surface with a diamond saw. Both crystals performed well with photon beam powers up to 1050 W and power densities of up to 14.5 W/mm2 at normal incidence. An infrared camera was used to measure the variation in the temperature of the top layer of the silicon crystals. For the core-drilled crystal the peak temperature measured at the center of the beam at a power density of 12.3 W/mm2 was 15 °C hotter than the crystal surface outside of the beam with a flow of liquid gallium of 2 gpm (gallons per minute) and was 10 °C with a flow of 4 gpm. The maximum distortion of the crystal surface distortion of the core-drilled crystal was about ±2.0 arcsec for the 2 gpm case with a maximum power density of 10.9 W/mm2 and about 5% of the expected beam intensity was lost at peak power of 14.5 W/mm2. For the slotted crystal the peak temperature difference for a peak power of 10.9 W/mm2 was 3.5 °C and 2.0 °C for liquid gallium flows of 1 gpm and 2 gpm, respectively. No intensity loss was measured for the maximum power density of 14.5 W/mm2. The fact that the peak temperature difference on the surface of both crystals was decreasing with increased flow of liquid gallium suggests that even higher power densities can be accommodated with higher flows of liquid gallium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143334
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  • 10
    Electronic Resource
    Electronic Resource
    Characterization of recombinant HIV-1 Tat and its interaction with TAR RNA (1992)
    s.l. : American Chemical Society
    Biochemistry 31 (1992), S. 12062-12068 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00163a014
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