Materials Literature
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Lon (or La) is a soluble, homooligomeric ATP-dependent protease. Mass determination and cryoelectron microscopy of pure mitochondrial Lon from Saccharomyces cerevisiae identify Lon as a flexible ring-shaped heptamer. In the presence of ATP or 5'-adenylylimidodiphosphate, most of the rings are symmetric and resemble ot…
We study by means of first-principles pseudopotential method the coordination defects in a-Si and a-Si:H, also in their formation and their evolution upon hydrogen interaction. An accurate analysis of the valence charge distribution and of the ``electron localization function'' (ELF) allows to resolve possible ambigui…
The zero-presssure zero-temperature equilibrium volume and bulk modulus are calculated for fcc Th and Pu by two independent all-electron, full-potential, electronic-structure methods: the full-potential linear augmented-plane-wave (FLAPW) method and the linear combinations of Gaussian type orbitals-fitting function (L…
In a recent paper DiMarzio and Yang [J. Res. Natl. Inst. Stand. Technol. 102, 135 (1997)] predicted that transport properties such as viscosity and diffusion coefficient do not follow the typical Williams, Landel, and Ferry (WLF) [J. Am. Chem. Soc. 77, 3701 (1955)] or Vogel–Fulcher-type of temperature dependence as th…
The autoxidation of Jet A, dodecane, and a dodecane-15%-cumene blend doped with sulfur compounds were studied at 433 K. Oxygen, hydro peroxide and soluble gum were monitored during the autoxidation. Dodecane, cumene, and the dodecane-15%-cumene blend autoxidized rapidly, while Jet A had an induction period followed by…
We prepared porous silicon for which the UV reflectance (3.3–6 eV) is nearly eliminated, and exhibits no features at the Si interband bulk transitions 3.3, 4.3, and 5.5 eV. Plating with a thin layer of copper is found to cause recovery of the UV bulk-like crystalline reflectance and interband resonances. This provides…
Reviewed are power system concepts employing the solid oxide fuel cell (SOFC) at atmospheric pressure in simple cycle; in an atmospheric pressure hybrid cycle with a gas turbine (SOFC/GT); and in a pressurized SOFC/GT hybrid (PSOFC/GT). Estimates of power system performance are presented and discussed. Simple atmosphe…
The ultrasonic velocity (V) and attenuation (α) have been measured for both longitudinal and transverse waves in the single-phase polycrystalline colossal-magnetoresistance compound La0.67Ca0.33MnO3 near the Curie temperature Tc. A dramatic increase in V is observed at the ferromagnetic transition temperature and acco…
Capacitors in metal–insulator–metal structure have been fabricated with different bottom electrodes. It has been found that the observed losses are enormous at gigahertz frequencies unless due care is taken not only for the conductivity of the bottom electrode but also its thickness. Very thin bottom electrodes (thick…
Plasma-sprayed mullite (3Al2O3·2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon-based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten s…
The use of SrTiO3 films in cryogenic high-frequency applications has been limited by the low dielectric constant εr of thin films (≈103) when compared to the bulk value of over 104. We show that the extension of the pulsed laser deposition technique to temperatures well above 1000 °C, coupled with in situ reflection h…
Mechanisms of polarization switching and fatigue in (Pb,La)(Zr,Ti)O3 (PLZT) films are studied by comparative analysis of degradation and leakage conduction of PLZT capacitors with Pt, SrRuO3 (SRO), and layered Pt/SRO (80/5 nm) electrodes. It is found that the asymmetrical Pt/SRO/PLZT/Pt structure exhibits a good fatig…
Aligned carbon nanotubes with open ends have been fabricated on silicon wafer in one step using a microwave plasma enhanced chemical vapor deposition system with a mixture of methane and hydrogen as precursors. High concentration hydrogen plasma and high negative bias voltage to the substrate induce anisotropic etchin…
Excellent symmetric dielectric hysteresis is observed from lead zirconate titanate (PZT) thin films using transverse electric fields driven by interdigitated surface electrodes. The 1-μm-thick PZT films with a Zr/Ti ratio of 52/48 are prepared on ZrO2 buffered, 4-in.-diam silicon wafers with a thermally grown SiO2 lay…
Large colored β-Si3N4 single crystals were successfully grown from a Si melt in N2. The transmission optical absorption of coloring β-Si3N4 single crystal shows that impurities introduce a midgap level of ∼2.4 eV into the wide band gap of ∼5.3 eV in nondoped Si3N4. The infrared transmission spectrum and electron probe…
Resonant x-ray scattering experiments at the vanadium $K$ edge demonstrate the existence of orbital ordering in ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$. Bragg peaks due to the long-range order of $3d$ orbitals occupancy are observed when the photon energy is tuned to the threshold of the vanadium $3d$ bands. The azimuthal…
The spin-wave theory and the coherent potential approximation are applied to a spin S Heisenberg antiferromagnet with nonmagnetic impurities on square lattice. The impurity effects are taken into account by substituting S(1-x) for S and using the coherent potential approximation to the exchange interaction, where x is…
A special shaping of YAG:Nd^{3+} laser beam profile has been found to improve homogeneity and T_c of YBa_2Cu_3O_{7-δ} films being deposited by the pulsed laser. Targets of a considerably non-stoichiometric composition and substrates of slanting cuts have turned to be necessary for the high-quality film growing. Multip…
High-quality indium tin oxide (ITO) thin films (150–200 nm) were grown on glass substrates by pulsed laser deposition (PLD) without postdeposition annealing. The electrical, optical, and structural properties of these films were investigated as a function of substrate temperature, oxygen pressure, and film thickness.…
Blends of polypropylene (PP) and ethylene propylene rubber (EPR) were studied. The effect of the level of rubber addition and the ethylene content is described. The results show that the viscosity of the PP, rubber content, ethylene content, and grafted EPR by maleic anhydride (MA) are important factors in controlling…