Materials Literature
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Time- and frequency-dependent measurements of optical phase conjugation in gold colloids are reported. It is shown that the nonlinear response is fast on a 5-psec time scale and can be assigned to the electrons of the small metal spheres. The frequency-dependent measurements were performed in the neighborhood of the s…
We review work on In2O3:Sn films prepared by reactive e-beam evaporation of In2O3 with up to 9 mol % SnO2 onto heated glass. These films have excellent spectrally selective properties when the deposition rate is ∼0.2 nm/s, the substrate temperature is ≳150 °C, and the oxygen pressure is ∼5×10−4 Torr. Optimized coating…
The relation between two well known charge-density-wave (CDW) transport phenomena, namely the apparent increase in the threshold field E T for continuous Frohlich conduction in short specimens, and the memory effect seen when the direction of current flow is reversed, is investigated in experiments on NbSe 3 at temper…
A model in which photoexcited electrons in small metal particles are scattered elastically from the boundaries and travel inelastically within is included in a free-electron theory which successfully explains the enhanced photoelectric quantum yield of these systems relative to macroscopic metal surfaces. Application…
The energy of an electron-hole pair in laser-excited semiconductor microcrystallites is computed with plasma screening and dielectric polarization taken into account. A strong excitation-induced blue shift of the absorption is predicted which causes a large optical nonlinearity for crystallite sizes exceeding the bulk…
The conformation of the glycine-rich loop of adenylate kinase is described in detail. It forms a giant anion hole for a sulfate ion, which presumably mimicks a nucleotide phosphoryl group. This loop had been called flexible, because at pH values of 6 or below it is displaced in the crystal. In the region of this loop…
We present investigations of the spreading behavior of nonvolatile liquids (high-molecular-weight polydimethylsiloxane) on smooth horizontal surfaces, and establish the following: (1) the existence of a thin precursor film extending progressively ahead of the macroscopic front of the drops, and that we directly visual…
Abstract Hindered amines and their derived oxidation products, the hindered nitroxyls and hydroxylamines are processing stabilizers and photoantioxidants for poly(vinyl chloride). The evidence suggests that oxidation of the amines occurs very rapidly and completely during mechanooxidation and that the resulting redox…
Abstract Graft copolymerization of acrylamide (AM) onto cotton–cellulose has been studied using a new class of acidic peroxo‐salt “potassium monopersulfate” as initiator catalyzed by Co(II). It is observed that the graft yield is influenced by the reaction time, temperature, and concentrations of the monomer, catalyst…
Abstract Elemental sulfur has been used to crosslink poly(arylene ether ketone)s. Evidence for crosslinking is presented in terms of rheological data of the melt. The effects of crosslinking on mechanical properties have been examined using tensile creep, stress–relaxation, and dynamic‐mechanical properties in torsion…
The room-temperature crystal structure of squaric acid (H 2 SQ), H 2 C 4 O 4 , has been determined by X-ray diffraction at 2.75 GPa; and the lattice parameters have been measured at a number of pressures between 0.93 and 4.70 GPa. Under these conditions, H 2 SQ is above the monoclinic-to-tetragonal transition temperat…
Abstract The swelling behavior of perfluorinated ionomer membranes in various solvents were studied. It was found that the sample pretreatments and the type of the functional group have a strong effect on the swelling properties of these membranes. The swelling of sulfonate membrane is higher than that of the carboxyl…
Abstract A new thermal conduction model is proposed for filled polymer with particles, and predicted values by the new model are compared with experimental data. The model is fundamentally based on a generalization of parallel and series conduction models of composite, and further modified in taking into account that…
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…