Materials Literature
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A family of rigid tetrahedral molecules based on tetraphenylmethane has been synthesized. The primary preparative chemistry involved Suzuki coupling. Reactions typically proceeded in good yields providing synthetic entry to tetrahedral building blocks for molecular engineering of architecturally regular macromolecular…
The preparation of aluminium nitride from organometallic or polymeric precursors is reviewed, including reaction conditions for the synthesis of various intermediates and their transformation into aluminium nitride, and examples of structural characteristics and processing features. Organoaluminium and organonitrogen…
Abstract This article addresses consumable selection and procedure development for the welding of stainless steels. The WRC-1992 diagram and the Schaeffier diagram, are used to illustrate the rationale behind many filler-metal choices. The article discusses the basic metallurgy and base metals of five major families o…
A method for the automated and accurate calculation of the winding eddy losses, as well as the stray losses in the tank walls, core support frame, lockplates, and the core laminations in core-form power transformers is described. Comparisons between this method, test values, and other analytical results are presented…
The behaviour of polymer dispersed cholesteric droplets in electric fields has been investigated for materials with both negative and positive dielectric anisotropy. Microscopic observations parallel and perpendicular to the electric field were performed. In materials with εa < 0, the cholesteric pitch remains constan…
The solid–liquid phase behaviour of binary and ternary mixtures containing water, sucrose and glycine has been studied by differential scanning calorimetry. In addition to defining the liquidus and solidus coexistence boundaries, the studies have been extended to the measurement of glass transitions of amorphous binar…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPoly(thiophosphazenes): new inorganic backbone polymersHarry R. Allcock, Jeffrey A. Dodge, and Ian MannersCite this: Macromolecules 1993, 26, 1, 11–16Publication Date (Print):January 1, 1993Publication History Published online1 May 2002Published inissue 1 January 1993https:/…
The generation of 6 wt.% potassium-modified alumina (K-Al2O3) from K2CO3-impregnated alumina (Al2O3/K2CO3) has been explored by means of surface and bulk analytical techniques, so as to characterize the interfacial synthetic events involved in the various preparative steps, namely: (i) wet impregnation, (ii) the dryin…
Abstract meso-Tetraalkylporphyrins were synthesized in good yields from aliphatic aldehydes and pyrrole by using the clay, montmorillonite K10. The nanometer size porous structures of K10 provide suitable reaction media for polymerization-cyclization condensations of aldehyde and pyrrole.
Abstract The causticization behaviour of Na 2 CO 3 with rock‐salt type oxide, Mg 2(1‐ x /(2+ x ) O (M = Al 3+ and Fe 3+ , x = 0.2 and 0.33), produced by the thermal decomposition of hydrotalcite‐like layered double hydroxide was investigated at 30–60°C. The degree of causticization increased with increasing the molar…
2-Amino-5-nitropyridinium halides have been synthesized and their crystal structures determined. The structures of acentric phases reveal networks of non-linear chromophores arranged in herringbone motifs. Their secondharmonic generation responses vary in magnitude between that of 3-methyl-4-nitropyridine N-oxide and…
A variety of definitions related to partial discharge (PD) phenomena are discussed. There is no general agreement at this time of writing as to the definitions of the various regimes of PD. A certain confusion exists which may be due to the multitude of PD manifestations. An attempt is made to elucidate some aspects o…
The identification and study of the electronic properties and location of CdSx(x < 1) and CdO particles in faujasites have been performed using X-ray photoelectron spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES) and fluorescence spectroscopy. These data were compared with results obtained by trans…
Auramine O exhibits a significant fluorescence emission at room temperature when adsorbed on microcrystalline cellulose. This emission is about two to four orders of magnitude higher than the previously reported emission in different solvents, also at room temperature. The fluorescence quantum yield, ϕF, varies with t…
Crystalline SUZ-4, with anhydrous composition K5Al5Si31O72, is hydrothermafly synthesized in a reaction mixture of SiO2, Al3, KOH, tetraethylammonium hydroxide and quinuclidine; its proposed framework topology is related to zeolites ferrierite and ZSM-57 and contains straight channels having apertures defined by rings…
Food emulsion stability is strongly influenced by the interactions in the adsorbed layer around emulsion droplets. Competitive adsorption of pure milk proteins (13-casein or 13 -lactoglobulin) with nonionic surfactants in oil-in-water emulsions is shown to depend on the age of the adsorbed protein layer. Evidence is p…
Abstract Difunctional acrylates and methacrylate monomers have been made which are high order smectic liquid crystal (or crystalline) at room temperature. This report discusses materials with the following structure: F–S–M–S–F, where F is a functional group, acrylate or methacrylate (A or M); S is a spacer (CH 2 ) n (…
Nematic droplets are intimately connected with disclinations, because in nematic droplets, point and line-shaped defects, as well as surface defects, are not generated at random, but inevitably by topological constraints. Thus, droplets provide a good means for investigating nematic defects. There is a growing interes…
The corrosion behaviour of aluminium in 1.0 mol l–1 solutions of HCl, H2SO4, HNO3 and HClO4 has been investigated in the presence and absence of added Cl– ions. The rate of corrosion of the metal in HCl and in acid solutions containing Cl–, was significantly higher than in the other solutions studied and is attributed…
The impedance of a poly(vinylferrocene)-modified electrode fits a transmission line model that has two resistances R1 and R2 and a capacitance CΣ. The low-frequency resistance, R1, passes through a minimum as the coat is oxidised. This is explained in terms of bimolecular electron-exchange reactions between redox cent…