Materials Literature
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Effects of Sb doping, sintering temperature and precoating with oxides on the optical and electrical properties of Sb-Sn-O thin films ~100 nm thick deposited by electron beam from bulk samples prepared using a sintering technique are investigated and discussed. All films have partially amorphous structure. The quality…
Cubylamines and cubylmethylamines are of interest as antiviral agents. Reliable syntheses of some polyamides with cubane as the backbone of a polymer chain are described. Two monomers of cubane, cubane-1,4-dicarboxylic acid (CDA) and 1,4-diaminocubane (DAC), are used. Polymerizations of DAC, 1,6-hexamethylene diamine…
The ionic conductivity in the system (1 − 0.08 x − 0.12 y )ZrO 2 –0.08 x Y 2 O 3 –0.12 y CaO (where x + y = 1 and y = 0–1) has been investigated using the complex impedance technique at 523–973 K. Doping CaO in the ZrO 2 –Y 2 O 3 system may result in an increase in the activation energy for lattice conduction and depr…
In metallic U-Pu-Zr fuel, metallurgical reactions occur between the fuel slug and the cladding, and a phase of which the melting point is relatively low is formed in the reaction zone. If a liquid phase is formed, it can degrade cladding integrity. The potential for liquid phase formation near the cladding, therefore,…
We have studied the dynamics of styrene−isoprene (SI) block copolymer micelles in a matrix of linear entangled polyisoprene (PI) chains, using forced Rayleigh scattering (FRS) and dynamic mechanical analysis (DMA). The molecular weight of PI has been varied from 22.000 g/mol, where the copolymer corona should be stron…
We calculate the low temperature, quantum mechanical rate of heat flow through a nanocrystal due to phonon transport by solving a many-body Schr\"odinger equation for oscillators in Fermi resonance. By analogy to Raman scattering through molecules, we find that normal processes due to anharmonicity of the nanocrystal…
Polycrystalline fine powder of yttrium aluminum perovskite (YAP) and yttrium aluminum garnet (YAG) have been successfully synthesized for the first time by mechanical solid-state reaction. The reaction scheme has been studied in detail. In short, the technique uses two reaction steps. First, a high-energy ball mill is…
Oxidation of MgO–C refractories containing 20 wt-%graphite was conducted by measuring the weight loss at regular intervals at various temperatures from 800 to 1600°C in air. The rate of decarburisation increased with rise in temperature from 800 to 1400°C and then remained more or less constant from 1400 to 1600°C. Th…
The minimum thickness for an amorphous silicon dioxide (α-SiO 2 ) protective coating required to prevent volume diffusion of atomic oxygen in a low Earth orbit (LEO) was evaluated by measuring the oxide thickness formed on Si(001) wafers in a hyperthermal atomic oxygen beam. The thickness of oxide film was measured by…
A theoretical method is presented to determine the gamma-radiation build-up factors in various biological materials. The gamma energy range is 0.015-15.0 MeV, with penetration depths up to 40 mean free paths considered. The dependence of the exposure build-up factor on incident photon energy and the effective atomic n…
The optical band gap and optical constants have been studied as a function of photon energy for a-Ga x Se100–x thin films (where x × 0, 2.5, 5.0, 7.5 and 10.0) in the wavelength region 450–1000 nm. The optical band gap decreases with the increase of Ga concentration in the a-Ga x Se100–x system. The refractive index (…
Fracture and environmentally assisted subcritical crack‐growth processes are examined in bulk Y‐Si‐Al‐O‐N oxynitride glasses with compositions typical of the grain boundary phase of silicon nitride ceramics. Both long‐crack (in compact tension specimens) as well as short‐crack behavior (using indentation techniques) w…
Crystalline phases present in the three NIST SRM Standard Portland cement clinkers 8486, 8487, and 8488 have been quantified from XRD powder patterns, ( CoK α radiation), using the full-profile Rietveld method. Included in the Rietveld refinement are rhombohedral (R), monoclinic (M), and triclinic (T) crystal polymorp…
The adsorption characteristics of phthalic acid on a silver surface were investigated by means of surface-enhanced Raman scattering (SERS). For a reliable analysis of the SER spectrum, we also performed an ab initio vibrational wavenumber calculation. The SER spectral features dictated that the phthalic acid molecules…
Our work demonstrates that magnetoresistance of the polycrystalline magnetite decreases with the reduction in average grain size, suggesting that the spin-dependent transporting phenomenon is associated with the interface microstructure. Also, the reducing peak intensity of the Raman spectra near 660 ${\mathrm{cm}}^{\…
A synchrotron X-ray diffraction study on hexagonal graphite-like boron nitride (h-BN) was performed under high pressures and temperatures. From the measured P-V-Trelation for h-BN (with a three-dimensional ordering parameter P3 = 0.9) in the temperature range from 298 to 1273 K and up to 6.7 GPa, the thermoelastic par…
Crystalline mullite was deposited by chemical vapor deposition (CVD) onto SiC/SiC composites overlaid with CVD SiC. Specimens were exposed to isothermal oxidation tests in high‐pressure air + H 2 O at 1200°C. Unprotected CVD SiC formed silica scales with a dense amorphous inner layer and a thick, porous, outer layer o…
Results are reported of a coordinated investigation of the dynamics of electronic excitations in LiB 3 O 5 and Li 2 B 4 O 7 crystals by low-temperature luminescence VUV spectroscopy performed with subnano-second resolution under synchrotron photoexcitation. Data on the photoluminescence (PL) decay kinetics, time-resol…
BACKGROUND: The main functional property of collagen is to provide a supporting framework to almost all tissues: the effects of non-enzymatic glycation on this protein are deleterious and in diabetes mellitus contribute to the mechanism of late complications. The aim of this work is to provide evidence by scanning for…
Os processos de gelatinização e de extrusão de amido de milho foram estudados. Calorimetria diferencial de varredura e miscroscopia óptica foram utilizadas na determinação da temperatura de gelatinização, T(G), em função do grau de umidade. Misturado a plastificantes, o amido foi processado em extrusoras mono- e dupla…