Materials Literature
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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…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of the gas-phase halogenation of a polyethylene surface as studied with x-ray photoelectron spectroscopyJames F. Elman, Louis J. Gerenser, Kim E. Goppert-Berarducci, and John M. PochanCite this: Macromolecules 1990, 23, 17, 3922–3928Publication Date (Print):August 1…
Low frequency dielectric measurements reveal two phase transitions in (CH3NH3)5Bi2Br11: at 311.5 K and 80 K. In the very vicinity of the ferroelectric phase transition at Tc = 311.5 K a nearly perfect Debye relaxation in the MHz region, with a critical slowing down of the relaxation frequency fε= ½πτε has been found.…
Abstract Polymerizations of phenyl glycidyl ether (PGE) and the diglycidyl ether of Bisphenol A (DGEBA) were initiated with tertiary amino alcohols. The reaction was followed by means of HPLC and IR spectroscopy. The main products isolated from the reaction mixture were identified by using mass spectrometry. The sol f…
The diffraction efficiency of a thin amplitude-phase holographic grating can be determined by a convolution operation of the diffracted amplitude series of both pure-amplitude and pure-phase gratings. Some examples of calculations are presented.
A radical anion salt based on thallium (see figure, where M = Tl) has been prepared. It is found to be the only such conducting compound, except the copper analogue, which shows a positive NMR knight shift indicating an electronic interaction between the central atom and the ligand. magnified image
The vibrational relaxation and dephasing of two-phonon states in the region of combinations or overtones of intramolecular vibrations in molecular crystals are discussed. The model Hamiltonian used includes (1) a harmonic part comprehensive of two-body intermolecular interactions that are responsible for the phonon di…
There are many simple models about fouling in the literature that calculate the optimum period for heat exchanger operation. Because of the assumptions and simplifications they contain, these models always yield, and often incorrectly, an optimum point. However, a more rigorous analysis indicates that the trend of fou…
The grain‐boundary resistivity of tetragonal zirconia polycrystals, which had undergone creep with different applied compressive loads and at different temperatures, has been measured with impedance spectroscopy. A stress exponent of unity was determined from strain rate versus stress data. The grain‐boundary resistiv…
Abstract Imide–aryl ether benzoxazole multiblock copolymers were investigated. A key feature of these copolymers is the preparation of bis(amino) aryl ether benzoxazole (PBO) oligomers via nucleophilic aromatic substitution. The molecular weights of the oligomers were 10,500 and 26,000 g/mol with T' g s of 210 and 227…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExtended Heuckel MO studies of boranes. I. Relative stabilities of closo-BnHn and -BnHn2-William W. Porterfield, Marion E. Jones, Wendy R. Gill, and Kenneth WadeCite this: Inorg. Chem. 1990, 29, 16, 2914–2919Publication Date (Print):August 1, 1990Publication History Publishe…