Materials Literature
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Thermal diffusivities of samples of UO2 and UO2 doped with 3, 5, 7 and 10 w/0 Gd2O3 were measured over the temperature range of 298~2,023 K by a laser flash method. Then thermal conductivities were calculated from them. The thermal conductivity decreased with increasing Gd2O3 content at low temperatures, while it was…
The structure of the boron suboxide B6O has been refined by the Rietveld method applied on X‐ray powder diffraction data. The samples were prepared by hot pressing amorphous boron and B2O3 and the data was collected with a STOE‐diffractometer equipped with a position sensitive detector. The structure belongs to the α‐…
Description 13 papers written by research tribologists are presented in chapters on: • What Mechanical Designers Need in Tribological Modeling • What is Available in Tribological Models • Data Base and Simulation issues for Tribiological Modeling • Simulation of Model Making and Use
A technique developed to measure the dissolution rate of glass fibers in the laboratory under conditions approximating those thought to exist in the lung has been applied to 30 glass compositions in the SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub>-B<sub>2</sub>O<sub>3</sub>-CaO-MgO-BaO-Na<sub>2</sub>O system. Dissoluti…
Cerro Chorrillos and San Jerónimo Quaternary volcanoes of northwestern Argentina erupted on a metamorphic Precambrian basement mostly covered by Paleozoic sandstones. Thickness of the continental crust is about 50 km and depth to the central part of the subducted slab is about 220 km. The lava series consists of absar…
The influence of environment on the cyclic fatigue behavior of a high‐purity alumina bioceramic was investigated using the repeated indentation technique. Tests were conducted in the presence of water, a variety of alcohols, toluene, and simulated physiological fluid environments. The results show that these environme…
Based on in situ X-ray diffraction and EXAFS studies, it is shown that NiTiO3 formed by the reaction of TiO2(anatase) with Ni2+ during the calcination of Ni/TiO2, gives rise to Ni metal and TiO2(rutile) on reduction, a process that may be responsible for the strong interaction between the metal and the oxide support.
An unambiguous particle-size effect has been observed in the desorption of oxygen from a faujasite-embedded platinum dispersion with distinctly different and narrow particle-size distributions. A kinetic analysis of the desorption spectra revealed a relative increase in the activation energy for desorption by about 60…
The structure of gaseous titanium tris(tetrahydroborate) has been determined by analysis of the electron diffraction patterns due to the molecules Ti(BH4)3 and Ti(BD4)3. The molecule has thus been shown to possess three tridentate BH4 groups generating a structure with C3h symmetry overall, implying nine-fold co-ordin…
Abstract Tetrabutylammonium salts of the mixed heteropoly molybdovanadate(V) anions, [Hx−1V(VxMo12−x)O40]4− (x=1–3) were prepared from a Mo(VI)–V(V)–CH3CN system at room temperature. These mixed heteropoly anions were distinguished by their voltammetric behavior; the anions with x=1, 2, and 3 were electroreduced by on…
Abstract The addition of small quantities 1–2% (w/w) of the sepiolite clay EXAL to animal feed increases the feed efficiency and weight of animals. α‐Chymotrypsin, lipase and α‐amylase from bovine pancreas adsorbed on to EXAL at different pH values form active stable complexes at enteric pH values. The enzymes are che…
We present here a spectroscopic structural characterization of octarellin, a recently reported de novo protein modelled on alpha/beta-barrel proteins [K. Goraj, A. Renard and J.A. Martial (1990) Protein Engng, 3, 259-266]. Infrared and Raman spectra analyses of octarellin's secondary structure reveal the expected perc…
The permanent magnet properties and the temperature dependence of Fe–Pt–Nb ternary alloys were investigated by using a recording fluxmeter, a vibrating sample magnetometer and an X-ray diffractometer.The excellent permanent magnet properties in the Fe–Pt–Nb system have been obtained by water-quenching from a temperatu…
All articles of this category Cerium(III) chloride as well as some other lanthanide salts invert the stereoselectivity of the reduction of bicylco[3.1.0]hexane-2,4-diones and bicyclo[3.1.0]hexan-2-ones 1 by sodium borohydride in methanol so as to favour attack of the hydride from the most hindered, concave face of the…
ABSTRACT Drainage of 14 protein‐stabilized foams was determined as a function of time. Drainage conformed to the empirical equation v = V t /(B + t), where v is the volume of drained liquid at time t, V is the maximum drained volume, and B is the time needed to drain V/2. Rate constants and initial rates of drainage c…
Charging occurs in ESCA because a non-conductive sample does not have sufficient de-localized, conduction band electrons available to neutralize the charged centers that build from clustering of the positive holes created with the photoelectron and/or Auger electron ejection. As a result, a positive outer (or Volta) p…
One-pot high-yield synthesis of the cubane-like complexes [{Mn(µ3-OH)(CO)3}4]1, and mixed-valence [Mn7(µ3-OH)8(CO)182, is reported: 1 and 2 have been characterized via X-ray crystallography, 2 being the largest Mn carbonyl complex yet structurally characterized.
Porphyrin-catalysed epoxidation of alkenes with hydrogen peroxide has been shown to occur in the presence of non-oxidisable ligands and bases whereas previous work has suffered from destruction of base and ligand with concomitant excessive use of oxidant. The advantageous use of adducts of hydrogen peroxide is describ…
MnIII–porphyrin 1, bearing an imidazole axial ligand and a carboxylic group juxtaposed on opposite sides of the porphyrin plane, is an extremely efficient catalyst for the activation of 30% H2O2 in hydrocarbon oxygenations carried out in CH2Cl2–H2O; initial rates at 1 min up to 500 turnovers min–1 at 0 °C in the epoxi…
We report spontaneous Brillouin and photon correlation spectroscopic results on the dynamics of the local density fluctuations in the ionic mixed salt xKNO3⋅yCa(NO3)2 with molar ratios 2:1, 3:2, and 1:1. For these mixtures, the density relaxation function g(t) changes from a stretched exponential (β=0.47) near the gla…