Materials Literature
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We discuss pattern formation in three-dimensional gels with cylindrical shapes during their shrinking such as volume phase transition. A Ginzburg–Landau theory is given for the pattern formation in shrinking gels. A characteristic feature in shrinking gels is the dense layer formed around the gel surface in the early…
Two surfaces that come in close contact in a solution with macromolecules present experience an attractive force caused by the osmotic pressure. We present a measurement of this effect by using a micrometer-sized sphere bound to a flat plate through a single molecular attachment in an albumin-containing solution. We o…
The possibilities offered by the modulated differential scanning calorimetry technique to investigate the glass transition are analyzed and discussed on Maltitol. The technique provides specific tools to follow the structural relaxation in the frequency domain above Tg and in the time domain below Tg. Evidence is obta…
Total energy minimization is applied to semiempirical tight-binding CdSe nanocrystal models with diameter up to 31 Å. The crystallites have wurtzite lattice structure and ligand-terminated surfaces. It is found that the qualitative features of the surface relaxation in nanocrystals and at bulk surfaces are similar. Wh…
A micropolar theory has been used to calculate the stress field generated by a fundamental boundary–value problem in planar elasticity; namely, a normal line force acting on the surface of a honeycomb half–space. In this two-dimensional analysis the microstructure of the honeycomb results in couple stresses and micror…
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…