Materials Literature
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Reflection high-energy electron diffraction (specular beam intensity) in migration-enhanced epitaxy of AlAs and GaAs has been investigated. The step flow growth mode was realized in the migration-enhanced epitaxy of AlAs by using a 0.5° misoriented GaAs(111)B substrate. In AlAs growth, excess As adsorption occurred ea…
The analysis of the dielectric dispersion has shown that in PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 ceramics with uncompleted B’ and B''-ions ordering the ferroelectric Curie points of the external and internal parts of the ceramic grain exist at different temperatures causing two anomalies in ε (T) curves. These results ar…
It has been shown that the use of a polarized attenuated total reflectance (ATR) infrared technique affords a means to study structure/frequency relationships and orientational behavior in partially oriented nylon (PON) yarns. In continuing studies, efforts have been directed toward the study of orientational developm…
A new kinetic model for thermal poly(vinyl chloride) (PVC) dehydrochlorination on the basis of Lottka's scheme has been developed. Its use allows us to reveal three kinetic transmission regimes to a stationary state. The model is expanded to account for the influence of the hydrogen chloride diffusion on the PVC dehyd…
The effect of boron on the hardenability of steels depends on the contents of such elements as aluminium, titanium, nitrogen, and boron and on the austenitising temperature. An attempt has been made to calculate the solubility of boron in the presence of aluminium, titanium, and nitrogen in steels. Three systems, Ti–B…
In this study we investigate the structural features that induce, modify or even inhibit the exhibition of liquid crystallinity in a series of aliphatic α-ω diquaternary and α-ω diphosphate amphiphiles. It was found that the appearance of thermally stable liquid crystalline phases is favored by increasing chain length…
Abstract This paper gives a review on the use of resonance Raman spectroscopy to analyse electronic and molecular structures of π‐conjugated and σ‐conjugated polymers. It starts with a short introduction into the present state of research in the field of conducting polymers and with a very short introduction into the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA bromide analog of a one-dimensional Ising ferromagnet: trimethylammonium catena-bis(.mu.-bromo)diaquoiron(II) bromideR. E. Greeney, Christopher P. Landee, J. H. Zhang, and W. M. ReiffCite this: Inorg. Chem. 1990, 29, 17, 3119–3125Publication Date (Print):August 1, 1990Publ…
Cubic BN was synthesized under high‐temperature and ‐pressure conditions from BN powder formed by pressure pyrolysis of borazine below 700°C and 100 MPa. The conversion of BN powder to cubic BN was strongly influenced by the residual hydrogen identified by the BH/BN ratio of IR absorption band. The activation energy f…
ADVERTISEMENT RETURN TO ISSUEPREVArticleProton nuclear magnetic resonance studies of iron(II/III)-amide complexes. Spectroscopic models for nonheme iron proteinsLi June Ming, Randall B. Lauffer, and Lawrence Que Jr.Cite this: Inorg. Chem. 1990, 29, 16, 3060–3064Publication Date (Print):August 1, 1990Publication Histor…
Although the degradation of polyvinyl fluoride (PVF) has been studied, emphasis has been placed on weight loss analyses and the study of the gases evolved during the degradation process. Little is currently known about the nature of the pyrolytic residue or of the chars which are formed during thermal degradation at h…
The permeation of oxygen through Ag normally occurs by a sequence of steps which include the initial dissociative adsorption of molecular oxygen at the upstream surface, the dissolution of the atoms into the bulk, and the subsequent migration of the atoms between octahedral sites of the lattice until they arrive at th…
The homeodomain from the engrailed protein of Drosophila has been crystallized from ammonium phosphate at pH 6.8. The crystals form in space group P6(1)22 (or P6(5)22), with cell dimensions a = b = 44.8 A and c = 118.2 A. These crystals diffract to 1.8 A resolution. A complex containing the engrailed homeodomain and a…
The N-n-alkyl-N′-(4-n-pentyloxyphenyl)-piperazines (4) exhibit ordered smectic phases at temperatures below 100°C. For 3, 4, 5 and 6 carbons in the alkyl chain, two smectic phases are present and for 7, 8 and 9 carbons only one smectic phase is present. The ΔH values for 4, 5, 6 and 7 carbons are anomalous. From optic…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSite of one-electron reduction of nickel(II) porphyrins: formation of nickel(I) porphyrin or nickel(II) porphyrin .pi.-radical anionG. S. Nahor, P. Neta, P. Hambright, L. R. Robinson, and A. HarrimanCite this: J. Phys. Chem. 1990, 94, 17, 6659–6663Publication Date (Print):Au…
The solution phase coordination chemistry assoicated with the 1:1 complexes of lanthanide ions with triethylenetetraaminehexaacetic acid (TTHA) has been studied by spectroscopic means. It was found that in the pH region of 3 to 7.5, the partially protonated Ln(TTHA) complexes exist as oligomeric species. A well define…
The wettability of poly(methyl methacrylate) and polyethylene by water and aqueous mucin solutions have been studied by sessile drop and under-water captive air bubble contact angles, respectively. From the sessile drop and octane under-water contact angles the polymer-water interfaces have been characterized in terms…
Reprinted with permission from Medicine and Science in Sports and Exercise (American College of Sports Medicine) 17:6 646-650, 1985. The Daily Adjustable Progressive Resistive Exercise (DAPRE) technique was developed clinically in an effort to provide an objective means of increasing resistance concurrently with stren…
The trapdoor deformity has been thought to be the result of contraction of the semicircular scar of the skin surface. The hypothesis is presented that a sheet of internal scar is primarily responsible for raising the skin inside the semicircle.
We have examined growth and stability of titania overlayers which have been vapor deposited onto a Rh foil. Titania was found to grow layer by layer, with approximately 1 × 1015 TiOx. species/cm2 in the first layer. Submonolayer coverages of titania were unaffected by heating the sample to temperatures as high as 1320…