Materials Literature
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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…
EXAFS and Molecular Dynamics combined study of CaO − FeO − 2SiO2 glass. New insight into site significance in silicate glasses, S. Rossano, A. Ramos, J.-M. Delaye, S. Creux, A. Filipponi, Ch. Brouder, G. Calas
Treatment of 1-(hydroxydimethylsiloxy)pentamethylcyclotrisiloxane ( II ), a latent A 2 A‘B monomer, with a phosphazene P 4 - t -Bu superbase followed by quenching with vinyldimethylchlorosilane/triethylamine leads to a hyperbranched polysiloxane ( III ). The microstructure and properties of III are compared to those o…
An aminosilane functionalized isocyanurate of 1,6-hexamethylene diisocyanate (HDI isocyanurate) was used to formulate coatings. The coatings were formulated using a mixture of the silane-functionalized isocyanurate and the unfunctionalized HDI isocyanurate. The general coating properties and tensile properties were ev…
We introduce a potential model for MgCO3 and CdCO3 which reproduces experimental structural parameters and solution energies. We employed atomistic simulation techniques to model the absorption and segregation of magnesium and cadmium ions to the low-index surfaces of calcite. Both magnesium and cadmium ions absorb at…
Cotton Sirospun® yarn has a circular cross-sectional shape, with the two strands segregated and consolidated into an adjacent array. When it is untwisted, the strand twists in an alternate direction. When compared to single yam with the same linear density and twist multiplier, cotton Sirospun yam is superior in tenac…
Nonphosphorylating nicotinamide adenine dinucleotide (phosphate)- [NAD(P)-] dependent aldehyde dehydrogenases share a number of conserved amino acid residues, several of which are directly implicated in catalysis. In the present study, the role of Glu-268 from nonphosphorylating glyceraldehyde-3-phosphate dehydrogenas…