Materials Literature
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A straightforward presentation of the broad concepts underlying radiological physics and radiation dosimetry for the graduate-level student. Covers photon and neutron attenuation, radiation and charged particle equilibrium, interactions of photons and charged particles with matter, radiotherapy dosimetry, as well as p…
Lactyl-CoA dehydratase consists of two enzymes, E1 and E2, and requires catalytic quantities of ATP for activity [Kuchta, R. D., & Abeles, R. H. (1985) J. Biol. Chem. 260, 13181-13189]. In contrast to E1, which contains no Fe, E2 contains 8.20 +/- 0.04 mol of Fe/mol of E2, one of which can be removed by 1,10-phenanthr…
Nitrogen-15 NMR spectroscopy has been used to study the hydrogen-bonding interactions involving the histidyl residue in the catalytic triad of alpha-lytic protease in the resting enzyme and in the transition-state or tetrahedral intermediate analogue complexes formed with phenylmethanesulfonyl fluoride and diisopropyl…
The 105-m drop tube at NASA/Marshall Space Flight Center has been used in a series of undercooling experiments on pure metals. Ti, Zr, Nb, Mo, Rh, Hf, Ta, and Pt were undercooled 17–20% of the melting temperature in a containerless, microgravity environment. Ir and Ru were undercooled to 13% Tm. Sample sizes ranged fr…
Bulk samples of Fe1−xNix, with x covering the whole concentration range 0≤x≤1, have been undercooled in a containerless state by electromagnetic levitation, yielding undercooling levels not achieved to date by any other technique. Comparison with a theoretical approximation indicates that, despite the large undercooli…
The influence of silicide reaction on the grain growth behavior of phosphorus-doped polycrystalline silicon has been studied. Intrinsic and phosphorus-doped polycrystalline silicon, with and without evaporated titanium overlayer, were prepared by low pressure chemical vapor deposition on thermally grown SiO2 on silico…
High-purity polycrystalline cadmium is creep tested in air at 22°C (0.5 Tm) and the stress-dip test used to determine the effective (σe) and internal (σ1) stresses. The stress-exponent of steady state creep is 2.24 for applied creep stresses, σ, less than about 20 MPa but increases to 6.12 at higher stresses, indicati…
The crystallographic quality and the surface morphology of ZnS films on (100) Si substrates by molecular-beam epitaxy are profoundly dependent on the substrate temperature Ts. When the Ts was below 300 °C, single crystalline films with twins grew along 〈100〉 directions in the initial stage of growth. However, when the…
We have measured the effect of elastic, uniaxial stress on the resistance R, the thermoelectric power (TEP), and the superconducting transition temperature ${T}_{c}$ of ${\mathrm{TaSe}}_{3}$. We find that there is a nearly discontinuous change in R and in the TEP at a stress \ensuremath{\sigma} of about 1.2 GPa at 20…
Trapping of ion-implanted deuterium (D) by irradiation defects and He bubbles in Mo was investigated through nuclear-reaction profiling of the D during linear ramping of temperature. Resulting data were analyzed using transport theory to obtain trap strengths. Nanometer-size He bubbles were found to trap the D with a…
Magnetic anisotropy of R2T14B (R=rare earth and T=transition metals such as Fe and Co) and partly substituted derivatives thereof are studied over a range of temperatures. The salient features are axial anisotropy for Y2Fe14B versus planar anisotropy for Y2Co14B. Only R with negative second-order Stevens’ factor (such…
The self-similarity property of the two-dimensional Penrose lattice is utilized to characterize it in terms of the distribution of different kinds of vertices, the Voronoi cells, and their nearest neighborhoods. Striking similarities are observed between the layer structures of the crystalline \ensuremath{\delta}-${\m…
The electrical conductivity and thermoelectric power of poly(p-phenylene vinylene) films have been studied as a function of heat-treatment temperatures (HTT's) up to 2900 \ifmmode^\circ\else\textdegree\fi{}C. The electrical transport is found to turn from a three-dimensional variable-range-hopping mechanism to metalli…
Photoluminescence studies have been performed on undoped and silicon-doped GaAs crystals, which were annealed between 650 and 1000 °C under different arsenic pressures. Samples were also heat treated with the addition of pure elemental Ga, Mn, or Cu. Spectra were taken in the energy range 1.15–1.55 eV at the surfaces…
Statistical properties of energy spectra in one-dimensional quasiperiodic systems are studied numerically. We find three distinctive level distributions: the Poisson, inverse-power-law (IPL), and cosine-band-like behaviors in the Harper model with an incommensurate potential. These depend on whether the electronic sta…
Magnetic properties of an orthorhombic intermetallic compound Mn 11 Ge 8 , which was formerly referred to as Mn 3 Ge 2 , has been investigated on a single crystal specimen at temperatures between 80 K and 800 K. The compound has features of a non-collinear antiferromagnet below T t = 150 K, and makes a spin-flopping t…
The shape of all major x-ray-excited peaks, including Auger transitions, from Cu, Ag, and Au are studied. The intensity contribution from inelastic (extrinsic) processes are removed. In all cases the primary excitation spectra thus determined are found to consist of a peak and a tail of (intrinsic) electrons which ext…
Initial magnetization and demagnetization data are reported for three forms of rapidly solidified Nd-Fe-B permanent magnet materials: melt-spun ribbons, hot-pressed magnets, and die upset magnets. In all three materials, the results are consistent with domain-wall pinning at Nd2Fe14B grain boundaries as the coercivity…
Simultaneous measurements of electrical conductivity \ensuremath{\sigma} and thermoelectric power Q were performed on a single crystal of ${\mathrm{Ba}}_{0.03}$${\mathrm{Sr}}_{0.97}$${\mathrm{TiO}}_{3}$ over an extensive range of temperature (500--1100?deC) and oxygen partial pressure (${10}^{\mathrm{\ensuremath{-}}18…
We present here a complete set of experimental results, obtained by electron paramagnetic resonance (EPR) and deep-level transient spectroscopy (DLTS), on the so-called EL2 defect in GaAs. It is obtained on semi-insulating materials and specially doped materials grown as semi-insulating ones, which have been submitted…