Materials Literature
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A simple electro-optical method was developed to characterize the temperature dependent viscoelastic coefficient of six nematic liquid crystals with different conjugation lengths. Results were then used to test seven most frequently used models for rotational viscosity (y1). Computer results show that some models fit…
The transition character of paraelectric-to-ferroelectric phase transition and its relation to lattice soft-mode behavior in the solid solutions of (Ba,Sr)TiO3, (Ba,Ca)TiO3, Ba(Ti,Zr)O3, and Ba(Ti,Sn)O3 were investigated by the measurements of dielectric constants in the temperature range from −30 to 150 °C, and x-ray…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal dehydration of calcium hydroxide. 1. Kinetic model and parametersAngel Irabien, Javier R. Viguri, and Inmaculada OrtizCite this: Ind. Eng. Chem. Res. 1990, 29, 8, 1599–1606Publication Date (Print):August 1, 1990Publication History Published online1 May 2002Published…
Abstract Na-beidellite, a member of the smectite group, was grown hydrothermally from a gel of composition 0.35Na 2 O·2.35Al 2 O 3 ·7.3SiO 2 in NaOH solutions at a pH between 7.5 and 13.5, a pressure of 1 kbar, and a temperature of 350°C. The synthetic Na-beidellite was characterized by means of scanning electron micr…
The synthesis and properties of calcium, strontium, and barium aluminoborate glass‐ceramics are described in this paper. Glass powder compacts near the RO‐Al 2 O 3 ‐B 2 O 3 stoichiometry were sintered and crystallized below 1000°C to form dense glass‐ceramics containing RAI 2 B 2 O 7 as the principal phase. Thermal ex…
Cation exchange capacity (CEC) and Al saturation are often determined by extraction of the bases with 1 M NH4OAc, pH 7, and the Al with 1 M KCl. This method was compared to 1 M NH4Cl to extract both bases and Al. The latter method has the advantages of measuring CEC at the soil pH and one‐step extraction. Data sets in…
Gas evolution experiments have been performed on hydrogenated amorphous carbon (a-C:H) films prepared by plasma deposition. Two series of films are studied: in series I, C2H2 is used as a process gas at a fixed bias voltage while the gas pressure is varied, and in series II, CH4 is employed at a fixed gas pressure, an…
Creep of 9.4‐mol%‐Y 2 O 3 ‐stabilized cubic ZrO 2 has been studied between 1300° and 1550°C. Conventional power‐law creep (stress exponent n ∼ 4.5) is found at the higher temperatures, with an activation energy (∼6 eV) corresponding to cation diffusion. Transition to a different creep mechanism occurs at the lower tem…
Crystals of tris (methylammonium) nonaiododibismuthate were grown which turned out to be isomorphous with Cs3Bi2I9 and (CH3NH3)3Sb2I9. Two phase transitions, at 223 (second order) and 142 K (first order), were revealed. The low temperature phase transition is characterized by a strong dielectric anomaly. The pyroelect…
The pharmacokinetics of Gd-DOTA meglumine in humans were evaluated in six healthy male volunteers. The agent was injected intravenously at 0.1 mmol/kg over approximately 2 minutes. Its behavior was found to be similar to that of urographic and angiographic iodinated contrast media with a plasma elimination half-life o…
Two typical lateritic weathering profiles (Jacuba ahd Angiquinho) from the Niquelandia Ni deposits, Brazil, were studied in order to establish the petrological relationship between the supergene Ni products and the parental pyroxenes. Frbm the base to the top of the profiles, pyroxenes are replaced by goethite and kao…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron pair donors in carbocationic polymerization. 2. Mechanism of living carbocationic polymerizations and the role of in situ and external electron pair donorsG. Kaszas, J. E. Puskas, C. C. Chen, and Joseph P. KennedyCite this: Macromolecules 1990, 23, 17, 3909–3915Publ…
The photochem. of colloidal ZnS was studied under a variety of exptl. conditions. The time dependence of the photocorrosion was examd. by using time-resolved fluorescence, static fluorescence, and electrospectroscopy for chem. anal. (ESCA) techniques. A qual. model for the semiconductor and its electrolyte interface i…
We have investigated with molecular dynamics the transport properties and velocity autocorrelation functions (VAF) for liqud ${\mathrm{SiO}}_{2}$ up to pressures of 20 GPa and at temperatures of 4000 K using 252--1371 particles. A systematic study of the sensitivity of the self-diffusion coefficient to the number of p…
Grain growth in a 50:50 (vol%) dual‐phase mixture of Al 2 O 3 and c ‐ZrO 2 (cubic zirconia) is severely limited compared with that for either of the single phases. At 1650°C, the growth rates in the duplex composition are 160 and 3500 times lower than that for single‐phase Al 2 O 3 and c ‐ZrO 2 , respectively. The res…
The synthesis of silanols 2 from the corresponding silanes 1 is especially easy, if the latter are allowed to react with dimethyl or methyl(trifluoromethyl)dioxirane (1–18 min reaction time, quantitative yields of enantiomerically pure product after removal of the solvent). The experimental data are consistent with an…
Poly(viny1 chloride) (PVC) has many desirable characteristics that have allowed it to achieve its present status as one of the most important commercial polymers. In spite of its enormous technical and economic importance, PVC still possesses many problems. Its rather low stability to the influence of heat and light r…
Textural, chemical, and mineralogical analyses of authigenic clays in anthracite-rank coal and associated shale from eastern Pennsylvania have allowed a better understanding of the parameters controlling diagenesis and perhaps coalification in this region. Minerals in anthracite occur in distinct assemblages associate…
The electronic structures of CuO and ${\mathrm{Cu}}_{2}$O have been investigated by resonant photoemission at the copper 3p threshold. The experimental data from CuO are compared with the results of a cluster calculation. From this analysis we confirm the dominant ${\mathit{d}}^{8}$ character of the states between 8 a…
Abstract A series of hydrothermal experiments was performed to determine the effect of fluid abundance on the reaction of smectite to illite. Experiments were conducted on K-saturated montmorillonite (<0.1- µ m fraction) in a closed system at 250° to 400°C using run times of 1, 7, 14, 30, and 60 days at 100 MPa (1…