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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of medicinal chemistry 33 (1990), S. 1848-1851 
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2216-2223 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The annealing behavior of amorphous, hydrogenated silicon carbide films in the range 400–900 °C was studied by optical characterization methods, 15N hydrogen profiling, and defect profiling using a variable energy positron beam. The films were deposited in an electron cyclotron resonance chemical vapor deposition system using ditertiary butyl silane [SiH2(C4H9)2] as the monosource for silicon and carbon. As-deposited films were found to contain large concentrations of hydrogen, both bonded and unbonded. Under rapid thermal annealing in a N2 atmosphere, the bonded hydrogen effuses giving rise to additional Si–C bond formation and to film densification. After annealing at high temperatures in N2, a marked decrease in the total hydrogen content is observed. After annealing in vacuum, however, the hydrogen effusion promotes void formation in the films. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 5424-5428 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An experimental approach to the study of thermal transport in the diamond-anvil high pressure cell is described and the elements of the thermal diffusivity tensor of β-oxygen are reported to a pressure of 9 GPa. The anisotropy in the thermal conductivity is found to be opposite in sense to that in the velocity of acoustic waves. Results are interpreted in terms of a lattice dynamical model in which the strong interactions between an atom and its first-, second-, and third-nearest neighbors are treated in tensorial form with parameters evaluated directly from experiment. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 910-916 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The spectrum of bound states of He atoms adsorbed on Ag(110) is calculated, using an interaction potential based on effective medium theory EMT for the repulsive term A exp(−bz) and the Zaremba–Kohn form for the attractive van der Waals dispersion term. The electronic charge density of the host in the selvedge region is modeled by superimposing atomic-charge densities using the Herman–Skillman tables and the prefactor A of the repulsive term is fitted to the exact ground state energy obtained from elastic He scattering data. Comparisons are made with the bound-state spectrum extracted from the measured resonances in the He scattering data and with the results of several other models used in the current literature. An assessment of the role played by higher-order dispersion contributions to the attractive potential is also included. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Standardization of the method to determine sun protection factors (SPF) is fundamental to uniform labelling of SPF values on sun products. The COLIPA Task Force ‘Sun Protection Measurement’(SPM), including representatives of major European sun-product manufacturers and contract testing laboratories, was established in 1990 to define methods for sun products testing. The process involved in developing the COLlPA SPF Test Method started with a critical appraisal of previously existing methods, and identification of areas for improvement. Experiments were performed by the participating laboratories to establish the new recommended test protocol which was then confirmed in two multicentred ring tests. Improvements to test methodology included the number and selection of volunteers and skin types, the application of the product, the definition of W output from solar simulators, and the method for assessing erythemal response (MED) including an option to use colorimetry to define objectively the ‘erythemal threshold’ of skin and to predetermine MED prior to exposure. Four cosmetic formulations and neutral density physical filters (SPF from 4 to 20) were tested in two ring tests. Results showed that variations in SPF of the cosmetic products were, on average, directly proportional to SPF value. An excellent correlation was found between visual and colorimetric SPF assessments (r = 0.99). An acceptable range of values for low and high SPF standard products was also established. The COLIPA SPF test method is now fully defined and supported by experimental data. Its use will harmonize SPF testing throughout Europe and help in the quest for global harmonization in testing sun products.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1520-6041
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 329-337 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We quantify the rates and total amounts of the arsenic for antimony exchange on both the Sb-terminated and Ga (or In)-terminated GaSb (001) surfaces using in situ real time line-of-sight mass spectrometry (LOS-MS) during molecular beam epitaxy. On the Sb-terminated GaSb (001) surface, an As for Sb exchange is observed to occur at all values of incident As2 flux considered. At high substrate temperature, three-dimensional (3D) nanometer-sized clusters from as a consequence of As/Sb exchange and lattice mismatch strain between GaAs and GaSb. The 3D clusters are found to have lateral dimensions of ∼10–30 nm and heights of 1–3 nm by atomic force microscopy (AFM). By contrast, at lower substrate temperatures a two-dimensional surface morphology is maintained, and AFM reveals an array of atomically flat terraces. On the surface terminated by one monolayer (ML) of Ga or In, there exists a critical As2 flux below which the As/Sb exchange is greatly diminished. The net amounts of Sb leaving the surface during one period of InAs/GaSb type-II superlattice growth are measured in real time by LOS-MS and estimated to be in the range of 0–0.4 ML for the various conditions used. By supplying only an As2 beam to a GaSb surface covered by InAs, the Sb riding over the InAs layer is replaced by arsenic and the total amount of such Sb is measured. The amount of Sb riding on the InAs can be as large as 0.8 ML for the first 1 ML of InAs and it gradually decreases to zero as the number of InAs monolayer increases. X-ray diffraction data show that all the InAs/GaSb superlattices coherently match with the GaSb substrate in the growth plane. The average lattice constant along the growth direction reduces with decreasing Sb mole fraction shown by the increased Sb desorption signal. Using the information on As/Sb exchange and Sb riding on the InAs surface, we predict an average lattice constant along the growth direction to be consistent with the measured one to within 2×10−4. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 5801-5808 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A revised pressure scale for NaCl is proposed as an update for the 30-year-old work of Decker. An alternative approach to the analysis is utilized in conjunction with more recent data. The zero-Kelvin compression curve is parameterized using local basis functions (splines) and constrained by accurate pressure-volume-temperature data. Thermal pressures are estimated within a quasiharmonic framework using a volume-dependent Grüneisen parameter and the Debye thermal energy. In the pressure regime extending to 5 GPa uncertainties in pressure (based on measured volumes) are estimated to be less than 1%. Uncertainty increases to 1.5% at 10 GPa and 3% at 25 GPa. The largest contribution to systematic uncertainty at the highest pressures is the lack of knowledge of the volume dependence of the Grüneisen parameter. Misfit of other calculated thermodynamic properties with respect to data is relatively small. On the basis of the current analysis, pressures determined using the older Decker calibration are low. Along the 300 K isotherm, apparent errors in the Decker scale are as large as −3% (−0.3 GPa at 10 GPa, −0.47 GPa near 18 GPa, and −0.37 GPa at 25 GPa). At higher temperatures the apparent errors are smaller. At 1100 K and 20 GPa the error is −0.2 GPa. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2136-2143 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The jet from a nominally axisymmetric shaped charge is formed by the collapse of the typically conical liner under the high pressures resulting from detonation of the explosive around it. Where asymmetries are present the velocities imparted to the elements of the liner at a given axial distance from the cone tip will vary as a function of the azimuthal angle among other variables. In general these elements will not meet at all. Conversely a pair of liner elements that do meet will in general have started from different axial positions, and will meet away from the nominal axis of symmetry of the charge. This effect renders the formation process asymmetrical. Consequently the jet particles have an off-axis velocity component which can substantially degrade the penetrative capability of the charge. A complete analysis of asymmetrical liner collapse and jet formation is presented for the case where the liner is axisymmetric, but there is an azimuthal variation in liner projection velocity. The classical analysis of symmetric liner collapse and jet formation is extended to include this type of asymmetry. Earlier work on linear shaped charges, particularly a model for asymmetric jet formation, is drawn upon to consider plane sections of the liner individually. A fully three-dimensional analysis is then achieved by the combination of the results for these sections. This analysis is implemented in a computational model and example results are presented and compared in as far as is possible and meaningful with previous theoretical and experimental results. Good agreement with the previous theoretical work is obtained, and the values of the off-axis velocity components predicted are of the orders observed in the limited experimental data as yet available.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 5357-5359 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The pressure-induced wavelength shift of a laser-excited fluorescence in samarium-doped yttrium aluminum garnet (Sm:YAG) was compared with that of ruby to 26 GPa at room temperature. Because the fluorescence wavelength for Sm:YAG has a negligible temperature dependence, it provides a better pressure scale for diamond anvil cell applications than ruby under high-temperature conditions. However, the overall intensity of the Sm:YAG fluorescence is less than that for ruby. A Gaussian–Lorentzian profile was chosen to analyze the fluorescence spectra. The Sm:YAG fluorescence wavelength exhibits an approximately linear pressure dependence (3.07±0.45 A(ring)/GPa) only to 20 GPa at room temperature. A polynomial fit for all data to 26 GPa gives P(GPa)=−10 280(λ/λ0−1)2 +2085(λ/λ0−1), with a rms misfit of 0.14 GPa.〈squeeze〉
    Type of Medium: Electronic Resource
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