Materials Literature
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Photoluminescence of erbium-implanted porous silicon is investigated. Room temperature 1.54 μm Er3+ luminescence is observed after annealing. The luminescence spectrum, annealing characteristics, temperature quenching, and the luminescence lifetime suggest that the Er3+ luminescence is mediated by photocarriers in the…
The TATA-binding protein (TBP) plays a key role in transcription initiation. Several negative cofactors (NC1, NC2, and Dr1) are known to interact with TBP in a manner that prevents productive interactions of transcription factors TFIIA and TFIIB with promoter-bound TBP. To gain insights into the regulatory interplay o…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of Molecular Weight Distributions of Polymers by MALDI-FTMSMichael. Dey, John A. Castoro, and Charles L. WilkinsCite this: Anal. Chem. 1995, 67, 9, 1575–1579Publication Date (Print):May 1, 1995Publication History Published online1 May 2002Published inissue 1 Ma…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBoron-Modified MCM-41 Mesoporous Molecular SievesAbdelhamid Sayari, Chistophe Danumah, and Igor L. MoudrakovskiCite this: Chem. Mater. 1995, 7, 5, 813–815Publication Date (Print):May 1, 1995Publication History Published online1 May 2002Published inissue 1 May 1995https://pub…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Half-Open Cage-Shaped Cluster, (NEt4)3[WOS3(CuBr)3(.mu.2-Br)].cntdot.2H2O: Synthesis, Structure, and Nonlinear Optical PropertiesZ. R. Chen, H. W. Hou, X. Q. Xin, K. B. Yu, and S. ShiCite this: J. Phys. Chem. 1995, 99, 21, 8717–8721Publication Date (Print):May 1, 1995Publi…
Abstract The possibility of reacting furfuryl alcohol with the p ‐position of phenolic rings, under acid conditions, was proved using different experimental techniques: size exclusion chromatography, Fourier transform infrared spectroscopy and 13 C NMR. This reaction was then used in the modification of phenolic novol…
Abstract Degradation of insulation systems by partial discharges (PD) is well known. Although measuring systems are used to classify PD activity, only little information is available about the relationship between PD energy and degradation. Internal PD‐ respectively gas‐discharge processes in spherical voids are calcu…
Abstract The polymer‐modified surface of kaolin was studied to determine the effect of changing the molecular weight of the polymer chain grafted on the surface. The particle was modified by attaching poly(ethylene oxide) to the surface using a urethane linkage. Upper critical flocculation temperature and contact angl…
Abstract Polytetrahydrofuran diols are polyurethane precursors obtainable from carbohydrate feedstocks. A range of commercial diols of different molecular weights were selected and supplemented by synthesised diols of lower molecular weights. To increase the carbohydrate content of derived polymers each diol was react…
The author explains how the ohmic behaviour of a bundle of conductors can be characterized by a complex resistivity. He provides an analytical expression, explicit and simple, of that resistivity and shows how to optimize an HF transformer, using that formula together with a previously published expression of the macr…
The aim of this work is to carry out a two-dimensional, non-linear, time-stepped finite-element simulation of a symmetrical short-circuit in a synchronous machine. Computed results of currents and rotorical torque are presented as comparison between computed reactances and test values.>
When a circuit containing a transformer is to be simulated, one must know the coupling coefficient or equivalent leakage inductances in addition to the other transformer properties. When other inductances in series with a transformer winding are large compared to the leakage inductance the leakage inductance may be ne…
Crystalline β‐Ta 2 O 5 coatings were deposited on hot‐isostatically‐pressed Si 3 N 4 by reacting TaCl 5 with H 2 and CO 2 in the temperature range of 1000°–1300°C and at a pressure of 660 Pa. The Ta 2 O 5 coatings generally consisted of wellcoalesced 2–3 μm grains, resulting in the formation of a nonporous coating mor…
The high-temperature radiation properties of isotactic and syndiotactic poly(methyl methacrylate) (PMMA) have been investigated by NMR spectroscopy. The tacticity changes for the isotactic PMMA during gamma-irradiation have been simulated by a model which allows for recombination of a scissioned bond and for the recom…
Thermal expansion of Y 4 A1 4 O 9 ceramics prepared at 1600° and 1800°C was measured from room temperature to 1500°C in air. Volume changes at the phase transition of Y 4 A1 2 O 9 , along with thermal hysteresis, were observed around 1400°C. The volume of the high‐temperature phase was about 0.5% lower than that of th…
The electrodeposition of copper, zinc and brass onto steel substrates from citrate-based alloy baths has been studied for a variety of bath compositions, temperatures and current densities. The influences of these variables on cathodic polarization, cathodic current efficiencies, quality of the deposits and compositio…
The sudden and unilateral decision by E. I. DuPont de Nemours & Co., Inc., to withdraw its polymers for use in implantable devices has presented the medical device industry with an immediate and serious challenge to find alternative sources of biomaterials. In France, the company Cardial S.A. has already taken steps t…
A synthesis of the physical, chemical, and mineralogical properties of soils developed on granitic rocks under different climatic conditions in Portugal was performed, including soil classification. Mean annual rainfall, the climate parameter best correlated with the variability of soil properties, was analyzed in ter…
In this paper, we describe a nondestructive method based on x‐ray reflectivity for measuring the thickness of porous silicon layers as well as the interfacial roughness between the porous silicon and the single‐crystal silicon substrate. Thickness and interfacial roughness measured using this method compare favorably…
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