Materials Literature
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Simple geometrical considerations predict 3 types of tilt grain boundaries in smectics A : curvature of the layers, arrays of dislocations and focal domains of equal eccentricity. These 3 possibilities are shown to exist in CBOOA (shear experiment). Their energies are discussed in terms of a simple model.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, characterization, and bonding of tetrameric triphenylphosphine silver halide cluster systems. Evidence of dictation of stereochemistries by van der Waals interactionsBoon-Keng Teo and Joseph C. CalabreseCite this: J. Am. Chem. Soc. 1975, 97, 5, 1256–1257Publicatio…
Abstract The purpose of this study was to investigate contact nucleation for various types of crystalline materials. Selected were aqueous solutions of two hydrated inorganic salts (MgSO 4 · 7H 2 O and KAl(SO 4 ) 2 · 12H 2 O), one nonhydrated inorganic salt (K 2 SO 4 ) and one organic substance (citric acid). Nucleati…
Gamma-ray buildup factors in ordinary concrete have been calculated by the moments method. Results for concrete kerma and air kerma are tabulated for source energies from 15 MeV to 15 keV. Parameters are given that allow calculation of the buildup factor by means of a simple analytic expression. Comparisons are made w…
If two metal plates are brought together at a sufficiently high relative velocity, a jet may form which removes much of the surface impurities, and a strong bond occurs. The purpose of this paper is to decribe the formation of a wave interface, and to suggest why a bond often occurs without the appearance of such wave…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics of the thermal decomposition of methyldisilane and trisilaneA. J. Vanderwielen, M. A. Ring, and H. E. O'NealCite this: J. Am. Chem. Soc. 1975, 97, 5, 993–998Publication Date (Print):March 1, 1975Publication History Published online1 May 2002Published inissue 1 March…
High-resolution single-crystal electron diffraction intensity data from fully hydrated, flat, rectangular catalase microcrystals are subjected to various tests which support the thesis that diffraction from crystals with thicknesses up to at least 1500 Å may be treated by the kinematical theory. The ratio of the total…
Abstract α-Ba2SiW12O40·16H2O is monoclinic, space group C2/c, with a=25.09(5), b=12.10(2), c=18.79(3) Å, β=122.5(3)°; Dm=4.95 g cm−3 and Dx=4.78 g cm−3 for Z=4. The crystal consists of the well known Keggin ion SiW12O404−, having a SiO4 tetrahedron in the center, bound by Ba2+ and water molecules to form a three-dimen…
Abstract The morphology of several series of segmented polyether–urethanes was studied. The “hard” segments contained urethane and urea linkages formed by 4,4′‐dicyclohexylmethane diisocyanate (Hylene W) and selected aliphatic and aromatic monomeric diamines (DA). The “soft” segments were composed of oligomeric poly(e…
The structures of {112} twin boundaries in body-centred cubic crystals have been studied using computer simulation methods and interatomic potentials representing iron, molybdenum and tungsten. Two distinct structures were found to be stable or metastable in the models used. These were the conventional twìn boundary d…
Abstract Recent work is presented on the plastic deformation of linear polyethylenes. This work demonstrates the importance of molecular weight and initial morphology in determining the drawing behavior, and shows that by appropriate choice of these two factors a substantial increase in draw ratio and hence stiffness…
A neutron-scattering study has been carried out on magnetite at temperatures just above the Verwey transition point of ${T}_{V}=123$ K. No critical scattering was observed at the (0,0,2) reciprocal-lattice point where the magnetic scattering appeared below ${T}_{V}$ due to the Verwey ordering as previously reported by…
Abstract Pronounced maxima in resistivity–temperature curves have been found at or above T g for a number of amorphous polymers (PS, PMMA, PVC) containing a small percentage of carbon black. The maxima appeared only after a certain period of storage at T < T g or at heating rates substantially higher than those use…
The use of triazole, benzotriazole, and naphthotriazole as corrosion inhibitors for copper is briefly reviewed. The corrosion of copper immersed in acidic, neutral, and alkaline solutions containing these compounds is reported. Triazole has generally been found to be a poor inhibitor, while benzotriazole and naphthotr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigher oxidation level phthalocyanine complexes of chromium, iron, cobalt and zinc. Phthalocyanine radical speciesJ. F. Myers, G. W. Rayner. Canham, and A. B. P. LeverCite this: Inorg. Chem. 1975, 14, 3, 461–468Publication Date (Print):March 1, 1975Publication History Publis…
A reversible photoinduced change in the intermolecular distance has been observed in a well−annealed As2S3 film using a detailed x−ray diffraction technique. This phenomenon is strongly related to the reversible optical absorption edge shift (i.e., photodarkening) by successive cycles of band−gap illumination and anne…
The transport characteristics of a hollow-fiber blood ultrafilter were studied in vitro to provide an understanding of the factors which control solute removal rate and to permit design of a full-scale clinical device. The dependence of ultrafiltrate flux on transmembrane pressure difference, protein concentration, fl…
We explore the problem of electrohydrodynamic instabilities in nematic liquid crystals in the parallel (planar) orientation, in the context of the one-dimensional time-dependent model proposed by Dubois-Violette, de Gennes and Parodi. In the first part of the paper, we solve the equations of motion analytically in the…
New substances of the type of unsymmetrical substituted biphenyls R1[MATH]R2 with R1 or R2 = n-alkyl, n-alkoxy and H-alkanoyl were synthezised. Miscibility measurements in binary systems, texture observation and comparative studies of the trends of the transition temperatures in homologous series yield a classificatio…
Summary The effect of heat treatment in air at temperatures from 200°C to 1000°C of two Cornish biotites has been studied using the M6ssbauer effect in 57 Fe. One of the micas was also studied after heating in vacuo . Progressive changes in the Mössbauer spectra of the materials after heat treatment can be correlated…