Materials Literature
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BACKGROUND: Two cases of allergic (IgE-mediated) reaction to bovine collagen are described. Both patients developed conjunctival oedema in response to the topical application of highly purified bovine collagen to the eye during opthalmic surgery (corneal shields and catgut suture material). One patient developed perio…
Atomic force microscopy, a powerful, high‐resolution imaging technique for determining the structure of surfaces in gaseous and liquid environments, was used to examine the reactivity of an electropolished surface of a naturally aged aluminum‐copper‐magnesium alloy (2024‐T3) in aqueous hydrochloric acid (0.01, 0.1, an…
Thermodynamic properties of the Cu-Ti system were optimised using experimental thermochemical and phase diagram data from the literature, leading to a consistent set of Gibbs energy parameters for the thermodynamic description of its equilibrium phases. Non-stoichiometries of the compounds Cu4Ti and CuTi were taken in…
Abstract A new morphology of ternary ABC triblock copolymers is presented which results from the asymmetric interaction between a centre block (poly(ethylene‐ co ‐butene)) to different end blocks (polystyrene and poly(methyl methacrylate)). This morphology with the appearance of a “knitting pattern” can be described a…
Abstract Shape memory polymers were prepared by copolymerizing stearyl acrylate and methyl acrylate. The principle of this shape memory effect is based on reversible order‐disorder transition of crystalline aggregates of stearyl moieties. A specific feature of this type of shape memory copolymer is that the transition…
Abstract The synthesis of the first example of an aromatic pyridine‐containing porphyrinoid 10 has been accomplished in excellent yields by the acid‐catalyzed “3 + 1” condensation of 3‐hydroxy‐pyridinedicarboxaldehyde ( 8 ) with tri‐pyrrane 9 . The key intermediate 8 was obtained by the selenium dioxide oxidation of t…
Gallium is a metal that literally melts in your hand. It has low toxicity, near-zero vapor pressure, and a viscosity similar to water. Despite possessing a surface tension larger than any other liquid (near room temperature), gallium can form nonspherical ...Read More
The control of chirality by optical molecular switches offers intriguing prospects in the design of new materials. For example, photochemically induced stilbene‐type cis‐trans isomerization of 1 (see Figure) results simultaneously in reversal of the helicity. The molecular design of switching units, the possibility of…
The cell parameters of deuterated gypsum have been extracted from Rietveld analysis of powder neutron diffraction data within the temperature range 4.2-320 K. The thermal expansion of gypsum is highly anisotropic along the b axis principally because of the effect of the D2.. .01 hydrogen bond. The high-temperature lim…
Prenyltransferases catalyze the consecutive condensation of isopentenyl diphosphate with allylic diphosphates to produce prenyl diphosphates whose chain lengths are absolutely determined by each enzyme. To investigate the mechanism of the consecutive reaction and the determination of the ultimate chain length, a rando…
A quantitative model for liquid phase sintering is developed based on the following ideas. During heating a liquid phase forms, which is easily mobile, wets the solid particles completely, dissolves solid atoms and provides an easy diffusion path for them. The solid density increases by particle rearrangement and by t…
Abstract Progress on the area of passivation of metallic materials by polyaniline is being presented. The redoxcatalytic reaction leading to the formation of a passivating oxide layer has been evaluated, and a reaction scheme is shown. Results of corrosion tests are described as well.
Structural, transport, and magnetic properties of ${\mathrm{Nd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ca}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ (0\ensuremath{\le}x\ensuremath{\le}1) have been studied to probe the consequence of strong lattice distortion and reduced double exchange. Charge ordering has been obse…
No abstract available.
Optoelectronic components require materials with large second‐order nonlinearities. Recently, various types of non‐classical chromophores have been developed, in the hope that they have improved physical properties for materials formation. The main research directions and latest developments reviewed here include mult…
Abstract The relationship between catalyst structure and enantioselectivity in the asymmetric epoxidation of unfunctionalized olefins by a series of chiral Mn(sa1en) complexes (1 – 10) was examined. The X‐ray structures of 5‐coordinate complexes 5, 8, of 6‐coordinate 9 ([6,6′= ‐ t Bu; 4,4 = ‐ t Bu] + ClO 4 − ), and 10…
Abstract A macroscopic energy balance model for crystalline swelling of 2:1 phyllosilicates is presented. Crystalline swelling for a static system is modeled by a balance among the potential energies of attraction, repulsion and resistance. The potential energy of attraction is due to both the electrostatic interactio…
During the processing of laminar ceramic, biaxial residual stresses can arise due to differential thermal contraction between unlike layers. A tensile stress can cause preexisting flaws to extend across the layer and into the adjacent layers and then tunnel until they meet either another crack or a free surface. A pre…
The effects of zero-point motion and the anharmonicity of the lattice vibrations of diamond have been explored theoretically in the context of a valence force model explicitly incorporating the isotopic composition. The predictions are tested in a study of the elastic moduli (${\mathit{c}}_{\mathit{ij}}$) deduced from…
Films of identically shaped, elongated, and parallel-oriented metal nanoparticles arranged in a regular pattern upon a transparent substrate were produced by use of electron-beam lithography. Because of the strong difference in the particles' polarizability components, the optical extinction spectra show strong dichro…