Materials Literature
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In peroxide crosslinked low density polyethylene for wire and cable applications there is a critical balance between the additives. Normally dicumyl peroxide is applied as the crosslinking agent and stabilizers are needed towards thermo-oxidative degradation as described by existing specifications. In addition, the ph…
Electron crystallography offers an increasingly viable alternative to X-ray crystallography for structure determination, especially for membrane proteins. The methodology has been developed and successfully applied to 2D crystals; however, well-ordered thin, 3D crystals are often produced during crystallization trials…
Additions of 1‐20 mol% Sc 2 O 3 or Y 2 O 3 to MoSi 2 eliminate glassy SiO 2 , which improves mechanical properties at both ambient and high temperatures. In particular, only 1 mol% ScO 3 additions dramatically enhance three‐point bending strength from 521 to 1081 MPa. Vickers hardness, Young's modulus, fracture toughn…
It is demonstrated that anodization of heavily doped n-type silicon in the dark is available for producing periodic silicon nanostructures. The relationship between the porous silicon (PS) morphology and the anodization parameters have been investigated in detail using high resolution scanning microscopy. Analyses of…
In this paper we review and discuss the possibility of having a 2D-nematic ordering of the surfactant polar heads in bilayer membranes. The coupling between the nematic order parameters and the curvature can yield instabilities in the shape of the membrane, generally leading to tubules with mesoscopic radiuses. The ne…
The morphological evolution of lithographically defined cracklike flaws in glass and glass‐containing ceramics was studied at elevated temperatures. The systems studied have glass contents from 100 to approximately 0.5 vol%, providing insight to the contribution of viscous flow of the glass to crack healing over a ran…
Abstract The point defect structure of a doped (oxide) system was quantitatively studied by applying in situ X‐ray absorption spectroscopy in the vicinity of the absorption edge of the dopant at high temperature ( T >270 K) and under defined oxygen activity. Based on refined phase diagrams of second kind (oxygen ac…
Striation-like hydrogen embrittlement (SHE) fracture occurs at low hydrogen concentration for an iron single crystal with a small carbon content, while cleavage fracture occurs at higher hydrogen concentration. The cleavage fracture initiated owing to hydrogen accumulated in front of the SHE crack tip propagates extre…
Discs of poly(aniline)-silver-polymer electrolyte particulate composites exhibit rapid and reversible changes in their microwave impedance when small electric fields are applied across them in a coaxial line test set in a resonant condition. The effect of composition on the cyclic voltammetry and microwave characteris…
Ferroelectric thin films of bismuth‐containing layered perovskite PbBi 2 Nb 2 O 9 have been prepared by a metalorganic decomposition (MOD) method. Random and highly c‐oriented films of the same starting composition have been obtained under different intermediate‐ and high‐temperature heat treatments. A comparison of t…
Eu 3+ -doped SiO 2, Al 2 O 3 −SiO 2, and P 2 O 5 −SiO 2 glasses were prepared by a sol−gel method from metal alkoxides, and their persistent spectral hole burning (PSHB) properties were investigated in relation to the local environment of the Eu 3+ ions in glass. Fluorescence line narrowing spectra indicated that Eu 3…
Poly(D,L-lactide-co-ethylene methyl phosphate) was synthesized by ring-opening polymerization of D,L-lactide (D,L-LA) and ethylene methyl phosphate (EMP) in bulk with Al(OiPr)3 as initiator. The influence of reaction conditions such as polymerization time, polymerization temperature and initiator concentration on the…
This research was directed toward a better understanding of the mass-transfer processes that occur in distillation columns containing structured packings. These packings are designed to create an-extensive gas−liquid interfacial area, through a combination of packing surface texturing and geometrical arrangement in th…
The photooxidation of bulk (1 mm) and thin (˜80 μm) samples of unfilled PVC free of photostabilizers was studied in various photoreactors in the 40–70°C temperature range. In bulk samples, the thickness distributions of photoproducts (carbonyls, conjugated polyenes, chain scission, crosslinks) and thermal stabilizer (…
The unusual three-dimensional tunnel framework of K2Ag3CeTe4 is built from the linking of [Ag2CeTe4]3- layers with Ag. This generates tunnels with an oval-shaped cross section with an accessible opening of 7.9 Å × 2.9 Å × 5.3 Å. These dimensions are large enough to permit the K+ cations to be accessible via topotactic…
Abstract The chemical composition of hydrothermal chlorite was determined by means of more than 200 electron microprobe analyses (EMPA) in almost all of the 70 chlorite-bearing samples taken from 5 boreholes in a study of the active geothermal system of Los Humeros, Mexico. Bulk rock composition of 6 different volcani…
It is well established that the dispersion of nanosized metal particles in a polymer matrix can induce nonlinear optical properties, yet very little is known about the effect of semiconducting transition metal oxide nanoparticles on luminescence properties of conjugated polymers. In this paper, we report the synthesis…
The pyridoxal form of alanine racemase of Bacillus stearothermophilus was converted to the pyridoxamine form by incubation with its natural substrate, D- or L-alanine, under acidic conditions: the enzyme loses its racemase activity concomitantly. The pyridoxamine form of the enzyme returned to the pyridoxal form by in…
Computer simulations of the dynamics of a colloidal particle suspended in a fluid confined by an interface show that the asymptotic decay of the velocity correlation functions is algebraic. The exponents of the long-time tails depend on the direction of motion of the particle relative to the surface, as well as on the…
In this article we describe research into the molecular design features for potential thermotropic biaxial nematogens of low-molar mass. We discuss how we can systematically change the shape of molecular structures in view of this aim of our work. The optical biaxialities of the materials prepared were tested through…