Materials Literature
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The liquid structure of dimethyl sulfoxide (DMSO) was investigated by X-ray diffraction. The intramolecular structure parameters were obtained as follows: S = 0 150(1) pm, C - S 180(1) pm, nonbonding C · · · O 267(4) pm and C · · · C 271 (7) pm. It is suggested that the molecular arrangement in the liquid state is sim…
A numerical model is developed for calculating the transformation of irregular waves due to refraction, diffraction and breaking. The model is based on a parabolic equation which is derived from the mild slope equation1) with an additional term of energy dissipation.In the present model, irregular waves are treated as…
The dissolution kinetics of crystalline and amorphous silica were studied as a function of time, temperature, concentration of HF, concentration of HC1, and crystallographic orientation. The results indicate that dissolution is a surface reaction‐controlled process. The dissolution rate depends strongly on HF concentr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeteropolyanions as nucleophiles. 1. Synthesis, characterization, and reactions of Keggin- and Dawson-type tungstostannates(II)Gayatri S. Chorghade and Michael T. PopeCite this: J. Am. Chem. Soc. 1987, 109, 17, 5134–5138Publication Date (Print):August 1, 1987Publication Hist…
Dedifferentiated chick embryo chondrocytes (Castagnola, P., G. Moro, F. Descalzi-Cancedda, and R. Cancedda, 1986, J. Cell Biol., 102:2310-2317), when transferred to suspension culture on agarose-coated dishes in the presence of ascorbic acid, aggregate and remain clustered. With time in culture, clusters grow in size…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUse of the Pariser-Parr-Pople approximation to obtain practically useful predictions for electronic spectral properties of conducting polymersPaul M. Lahti, Jan Obrzut, and Frank E. KaraszCite this: Macromolecules 1987, 20, 8, 2023–2026Publication Date (Print):August 1, 1987…
The luminescence properties of Ce 3+ ‐ and Tb 3+ ‐activated and of Tb 3+ ‐activated are reported. It is shown that activated with Tb 3+ is an excellent phosphor both under UV and x‐ray excitation. In both types of compounds there are two different Ln 3+ sites available for the activator ions, Ce 3+ and Tb 3+ . The res…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHighly reactive magnesium and its application to organic synthesesTimothy P. Burns and Reuben D. RiekeCite this: J. Org. Chem. 1987, 52, 16, 3674–3680Publication Date (Print):August 1, 1987Publication History Published online1 May 2002Published inissue 1 August 1987https://p…
The degradation of tin-doped indium-oxide (ITO) films in glow-discharge plasmas of hydrogen and argon have been investigated. Parameters which have been varied for the study include the temperature of ITO under ion bombardment, the rf power density, the time of exposure to plasma, and the gas flow rate. After bombardm…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransition of linear polymer dimensions from .THETA. to collapsed regime. 1. Polystyrene/cyclohexane systemI. H. Park, Q. W. Wang, and Benjamin ChuCite this: Macromolecules 1987, 20, 8, 1965–1975Publication Date (Print):August 1, 1987Publication History Published online1 May…
Solutions of tetramethoxysilicon were reacted, using both acid and base as catalysts, until near the sol-gel transition. Portions of the reacting mixture were quenched by dilution, and the average cluster mass and correlation length were measured with use of static and dynamic light scattering. Critical exponents desc…
Arginine 179 of the alpha subunit of tryptophan synthase of Salmonella typhimurium was changed to leucine by site-directed mutagenesis. The mutant alpha subunit was expressed in S. typhimurium, purified and crystallized as the alpha 2 beta 2 complex, and characterized by kinetic studies under steady-state reaction con…
Abstract Crystal structure of uncomplexed γ-cyclodextrin, C48H80O40·14.1H2O, was determined by the X-ray method. The crystal is monoclinic and the space group is P21 with cell dimensions; a=16.847(2), b=11.098(2), c=20.271(2) Å, and β=104.97(1)°. The structure was solved by the inspection of a Patterson map and the R-…
The dielectric properties of liquid water are studied using an empirical potential model treating the monomers as flexible molecules with short-range interactions between oxygens and Coulomb interactions between charges situated on the individual atoms. Satisfactory results for the static dielectric constants at 259,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal stability and kinetic lability of the metal carbonyl bond. A theoretical study on M(CO)6 (M = chromium, molybdenum, tungsten), M(CO)5 (M = iron, ruthenium, osmium), and M(CO)4 (M = nickel, palladium, platinum)Tom Ziegler, Vincenzo Tschinke, and Charles UrsenbachCite…
Abstract A rheological technique is proposed for determining the thermally induced order–disorder transition of block copolymers. In the present investigation, a cone‐and‐plate rheometer was used to measure dynamic storage and loss moduli, G ′(ω) and G ″(ω), as a function of angular frequency ω of a commercial grade p…
Point-contact transistors and Schottky diodes have been formed on synthetic boron-doped diamond. This is the first report of diamond transistors that have power gain. Further, the transistors exhibited power gain at 510°C and the Schottky diodes were operational at 700°C.
The efficiency of a Lyot stop in reducing diffraction effects in a simple optical system is analyzed. The transformation rules of Fourier optics are used to follow the optical signal through the system. This analysis reduces the problem to the evaluation of a two-dimensional integral. An approximate analytic technique…
Abstract The optical properties of bisphenol‐A polycarbonate resin as described by the complex index of refraction, N = n – ik , are derived by Kramers‐Kronig analysis of experimental absorption and reflectance data obtained in the range 40μm ≥ λ ≥ 105 nm. Electronic absorption processes in polycarbonate are character…
In Escherichia coli strains overproducing dinucleoside tetraphosphate hydrolase, the accumulation of dinucleoside tetraphosphates (AppppN, with N = A, C, G, or U) during heat shock or H2O2 treatment was reduced about 10-fold as compared with a control strain. This accumulation neither modified the pattern of the prote…