Materials Literature
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The theoretical model underlying a two-strand spinning system is given. It is shown that, for an idealized model, the equilibrium twist in the strands is dependent upon a torsion balance existing between an individual strand above the convergence point and the strand as it lies in th plied structure. As a consequence,…
Abstract The effects of thermal oxidation on the‐ molecular structure and on the morphology of a series of high‐density polyethylene pipes have been studied “as received” or after service. The existence of a 40 to 170 μm thick oxidation skin was established, the structure and morphology of which were characterized by…
Finite difference and finite element methods are investigated as applied to Laplace and Poisson linear equations in two dimensions. The comparative analysis concentrates on first-order square, rectangular, triangular and polar algorithms which are characteristic to each method. The results are found to be independent…
The chemical identification of chlorophyllide (E458F674) (Belanger, F. C., and Rebeiz, C. A. (1980) Plant Sci. Lett. 18, 343-350) has been confirmed by chemical derivatization coupled to spectrofluorometric, spectrophotometric, and chromatographic analysis. Chlorophyllide (E458F674) and its demetallated analog were co…
BIS[(1-PHENYL-1-CYCLOPROPYL)CARBONYL] PEROXIDE 1679 such a conformation unfavourable. The observed conformation is 21 o from the perpendicular geometry. It appears, therefore, that the observed geometry is a consequence of a balance between two opposing constraints: (i) maximization of orbital overlap between the n sy…
Abstract The degradation of isotactic polypropylene in the range 390–465°C was studied using factor‐jump thermogravimetry. The degradations were carried out in vacuum and at pressures of 5 and 800 mm Hg of N 2 , flowing at 100–400 standard mL/s. At 800 mm Hg this corresponds to linear rates of 1–4 mm/s. In vacuum bubb…
The complete reduction of a fourth-rank Cartesian tensor into parts wich are irreducible under the three-dimensional rotation group is presented. Results are given for the general case of a tensor without index permutational symmetry, and also for tensors with specific index symmetry properties. Applications in the re…
In this first sentence of his seminal book “The Physics of Liquid Crystals,” Pierre Gilles de Gennes has succinctly stated the appeal that liquid crystals have for all of us working in this field. The term “liquid crystal,” in fact, refers to a number of distinct states of matter that have structural order intermediat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoresponsive complexation of metal cations with an azobenzene-crown-azobenzene bridge immobilized in polymer supportsSeiji Shinkai, Hidefumi Kinda, and Osamu ManabeCite this: J. Am. Chem. Soc. 1982, 104, 10, 2933–2934Publication Date (Print):May 1, 1982Publication History…
The open circuit growth of the thin oxide films on titanium in 0.5N solutions of H2SO4, NaOH, and Na2SO4 is studied. The results indicate markedly the dependence of the growth behavior on the electrolyte composition. Anodic oxide film growth on titanium is carried out in 0.5N H2SO4. After interruption of the current,…
Abstract The cooperative binding of n ‐mers to a finite ring, a finite open chain, and an infinite chain is treated in a unified way using the matrix method. For an infinite chain, the implicit closed‐form expression (“Scatchard formula”) for the fraction of bound sites obtained by McGhee and von Hippel, is simply red…
Annealing of acceptor dominated α-Al2O3 at Tsat = 1100–1500 °C in atmospheres containing hydrogen leads to dissolution of hydrogen, changing the material from p- to n-type when the concentration of hydrogen donors is larger than that of the acceptor impurities present. If oxygen equilibrium is maintained, the concentr…
A self-consistent interpretation of the Raman and infrared spectra and the heat-capacity measurements on Dy2O3, Er2O3, and Yb2O3, which have the cubic (bixbyite) structure, is presented. New spectra recorded at 10, 80, and 300 °K on oriented single crystals of each oxide are compared with published spectral data and i…
Audio frequency a.c. loss measurements in sputtered hydrogenated amorphous germanium films made over the temperature range 30–150 K are described. The measurements show similar features to those previously reported for evaporated films, namely a frequency exponent which decreases with temperature and a low-frequency l…
The scattering of electromagnetic waves from a periodic dielectric interface is studied for a general angle of incidence. It is called conical diffraction in grating theory for the general case where the incident wave vector is not perpendicular to the ruling direction of the gratings. We adopt the electric and magnet…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFragmentation mechanism and energetics of some alkyl halide ionsH. M. Rosenstock, R. Buff, M. A. A. Ferreira, S. G. Lias, A. C. Parr, R. L. Stockbauer, and J. L. HolmesCite this: J. Am. Chem. Soc. 1982, 104, 9, 2337–2345Publication Date (Print):May 1, 1982Publication History…
Soft contact lenses and ablative heat shields for spacecraft require materials with vastly different physical properties. Yet the materials for both—permeable elastic membranes and tenacious high-temperature composities—are products of polymer science.
Condensation of chiral S-4-(6-methyl)octyloxy-2-hydroxybenzaldehyde (S-4-0- (6-methyl)octylresorcylaldehyde) with 4-alkylanilines (the MORA series, 3) gives low-melting Schiff bases showing chiral smectic C phases at or slightly above room temperature. The previously known MBRA series (4'-0- (2-methyl)-butyl- resorcyl…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDimensional probes of enzyme-coenzyme binding sitesNelson J. LeonardCite this: Acc. Chem. Res. 1982, 15, 5, 128–135Publication Date (Print):May 1, 1982Publication History Published online1 May 2002Published inissue 1 May 1982https://pubs.acs.org/doi/10.1021/ar00077a001https:…
We introduce a method, which is free of specimen edge effect, for the determination of critical stress in material brittle fracture. Using this method, we have investigated the critical stress in silicon brittle fracture. Silicon wafers polished with silica gel showed an average fracture stress of 2.8 GPa, with a stan…