Materials Literature
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Ansl:n.Lcr Unit-cell dimensions of muscovite-2M, from the Diamond mine, South Dakota, were determined to 1000'C, single-crystal X-ray structural refinements were made at 20'C and 300'C, and additional structural refinements at 20, 525. and 650'C were made on similar material from Panasqueira, Portugal. Single-crystal…
Abstract The weathering of eastern Australian basalts, sampled from the rounded, hard, core-stone to the rind of softer weathered material, has been examined by bulk chemical analyses, thin section petrography, electron microprobe, and X-ray powder diffraction analyses. Using density as a measure of weathering intensi…
The space-group symmetry implied in the atomic coordinates of a structure can be reconstructed by deriving the metric symmetry elements of the lattice from the cell data, and finding the location and the glide for corresponding space-group symmetry elements with the same orientation using the list of atomic coordinate…
Glutaraldehyde crosslinking of native or reconstituted collagen fibrils and tissues rich in collagen significantly reduces biodegradation. Other aldehydes are less efficient than glutaraldehyde in generating chemically, biologically, and thermally stable crosslinks. Tissues crosslinked with glutaraldehyde retain many…
A comprehensive review of the Nd–Fe–B permanent magnet material is given. A historical survey, the basic magnetic properties of Nd 2 Fe 14 B and isomorphous compounds, a phase diagram for the ternary Nd–Fe–B system, processing techniques and magnetic properties of sintered Nd–Fe–B magnets, and the future directions fo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of ion populations and solvent content as functions of redox state and pH in polyanilineDuke Orata and Daniel A. ButtryCite this: J. Am. Chem. Soc. 1987, 109, 12, 3574–3581Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Publis…
Liquid crystals and polymer glasses can be formed into orientationally ordered materials by raising the temperature of the material to a temperature at which molecular motion is greatly enhanced, applying an external aligning field, and then cooling with the field applied. The resulting material exhibits second-order…
Heteropolyanions are polymeric oxoanions which are formed by the condensation of more than two different oxoanions [Eq. (1)l. Polyanions consisting of one kind of oxoanion are called isopolyanions [Eq. (2)]. Acidic elements such as Mo, W, V, Nb, and Ta are present as oxoanions in aqueous solutions and polymerize to fo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructural-electronic relationships in inorganic solids: powder neutron diffraction studies of the rutile and anatase polymorphs of titanium dioxide at 15 and 295 KJeremy K. Burdett, Timothy Hughbanks, Gordon J. Miller, James W. Richardson Jr., and Joseph V. SmithCite this:…
Two competing types of thermal reactions of monomers of different classes, namely oligomerisation and polymerisation, are examined. The characteristics of the formation of the initiating radicals and of low-molecular-weight products (dimers and trimers) and of the inhibition of the thermal polymerisation by radical ac…
The most significant feature in the transition from the quasicrystalline to the amorphous state is the loss of long-range bond-orientational order. Disclinations are candidates for elementary excitations which destroy angular correlations. Generalizing the topological defect classification, we investigate point singul…
Temporal oscillations in the specular beam of reflection high-energy electron diffraction (RHEED) provide the primary method of monitoring growth by molecular-beam epitaxy. We develop a model to investigate the origin of these oscillations with which, by monitoring the step density of a growing sample, we are able to…
Abstract The emission of weak visible chemiluminescence (CL) during the cure of a tetraglycidyl 4,4′‐diaminodiphenyl methane (TGDDM)‐based epoxy resin, with three different concentrations of 4,4′‐diaminodiphenylsulfone (DDS) has been studied at 135°C. Spectral analysis indicates that the CL originates from trace oxida…
Abstract Complete conversion of the crystal form in cotton fibers to cellulose IV (cell IV cotton) was obtained by heat treatment of ethylamine‐treated cotton cellulose in either saturated steam or formamide. Degradation of the fibers was not extensive during the conversion process; oxidative damage appeared to have b…
Abstract Triphenylchloromethane and p ‐toluenesulfonyl chloride were reacted with chopped or powdered cellulose, with and without premercerization, to form trityl–cellulose ethers or tosyl–cellulose esters. Powdered and premercerized cellulose samples were more readily derivatized. Differential scanning calorimetric (…
Abstract The effect of the physical aging of ethylene ionomers was studied for the samples with the acid content of 5.4 mol%, and the degree of neutralization, 0%, 60% Na, 60% Zn, and 90% Zn. The information about the crystal and the cluster part of the physically aged ionomers was obtained by differential scanning ca…
Abstract A comprehensive examination of the die‐drawing behavior of polypropylene has been carried out, examining the effects of draw temperature, haul‐off speed, and initial billet size. A range of oriented products was obtained and characterized, primarily by the determination of Young's modulus at room temperature,…
Abstract The reaction of EPR with dicumyl peroxide at 180°C or t ‐butyl perbenzoate at 140°C resulted in the formation of a fraction insoluble in cyclohexane at 22°C. The presence of maleic anhydride (MAH) in the EPR‐peroxide reaction mixture increased the amount of insoluble polymer, whose concentration decreased as…
Abstract The influence of macroscopic dimensions, heat treatment, and polymer morphology on the chemical degradation of poly(glycolic acid) (PGA) fibers and pellets was examined in media of different pH values by monitoring the sample mass, dimensions, crystallinity, mechanical strength, and surface character. The deg…
The role of the secondary structure in the folding mechanism of dihydrofolate reductase from Escherichia coli was probed by studying the effects of amino acid replacements in two alpha helices and two strands of the central beta sheet on the folding and stability. The effects on stability could be qualitatively unders…