Materials Literature
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The resistivity and magnetization of layered perovskite ${\mathrm{La}}_{2\ensuremath{-}2x}{\mathrm{Ca}}_{1+2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ have been studied systematically using bulk samples with a wide doping concentration range $0<~x<~0.5$ and epitaxial thin film samples with $x=0.3.$ The system becomes…
Starburst PAMAM dendrimers ending with mannopyranoside residues were readily synthesized in large scale and good yields from commercially available dendrimers bearing high-density amine functionality on their surface and p-isothiocyanatophenyl 2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranoside. The first four generations…
As shown by time- and temperature dependent SAXS experiments, crystals of s-PP do not change their thickness during isothermal crystallization and a subsequent heating to melting. This allows an accurate determination of the relations between crystallization temperature, crystallite thickness, rate of crystallization,…
We report experimental evidence of macroscopic quantum tunneling in antiferromagnetic particles. The zero-field maximum in the dependence of the magnetic relaxation rate on the magnetic field in ferritin has been observed. This observation provides a new insight into the origin of the nonmonotonic field dependence of…
The electronic structure of amorphous diamond-like carbon is reviewed. The sp2 sites form small, mainly chain-like clusters which control the bandgap. Detailed analysis shows that all π states within the σ-σ* gap are all localized; so the mobility gap greatly exceeds the optical gap. This accounts for the photolumines…
A localization model comprising spin disorder and nonmagnetic randomness is presented to account for novel magnetotransport properties in Mn oxides ${R}_{1\ensuremath{-}x}{A}_{x}{\mathrm{MnO}}_{3}$. Localization length of electrons as a function of magnetization is determined by means of the transfer matrix method. In…
The syntheses and characterization of silicate/surfactant thin films with the structure P 6 3 / mmc is presented. The films are synthesized using a novel double-headed quaternary amine surfactant and can be grown either on mica or at the air−water interface. Films are shown to be crystalline and oriented with the c -a…
Intramolecular H-atom-transfers (IHTs) in curcumin (enol) and its mimic, 1,6-heptadiene-3,5-dione (enol), in ground state and excited state were investigated by ab initio and CIS methods in this paper. It is revealed that double ortho-methoxy-phenolic rings have little effect on the IHT barrier of curcumin, and the IH…
A study of specific features in the kinetics of thermoluminescence (TL) of defective α -Al 2 O 3 crystals is reported. The TL properties are experimentally shown to be related to the presence of oxygen vacancies of thermochemical or radiation origin. It is established that the differences in the TL kinetics in α -Al 2…
The permeation of protium, deuterium, and an equimolar deuterium-tritium mixture through finger-type Pd-Ag permeators of various configurations operated either in/out or out/in has been compared in parametric studies. The parameters included the permeate pressures; the feed-and-bleed flow rates; and the feed-gas compo…
Despite many years of research, the detailed atomic structure of many important carbon materials remains poorly understood. In particular, the structure of those carbons which can not be transformed into graphite by high temperature heat treatment has never been clearly established. These non-graphitising carbons are…
Abstract The effects influencing the migration of different small molecular materials in polyethylene (PE) were studied. A decrease in weldability experienced after storage of the polymer at ambient and elevated temperatures was proved to be a result of migration of low molecular mass components of the polymer and som…
The dehydration reaction kinetics of tincal and borax decahydrate was investigated by thermogravimetry (TG) and differential thermal analysis (DTA). Various methods were used to analyze the TG and DTA data for determination of reaction kinetics. The activation energy, frequency factor, and order of reaction were calcu…
Unpolarized single‐crystal Raman spectra in the temperature interval of 298–1235 K and powder X‐ray diffractometry data from room temperature up to 1295 K have been obtained from a natural triclinic wollastonite of almost‐ideal composition. Room‐temperature spectra, along with the temperature dependencies of nine majo…
High-temperature annealing of thick silver films (TSFs) deposited onto a smooth dielectric substrate leads to high-order self-organization of metal clusters on the film surface. A comparative atomic force microscopic (AFM) analysis of “as-deposited” and annealed TSFs (aTSFs) shows that uniform ellipsoidal roughness ∼4…
Poly(N-vinylcarbazole), poly(N-carbazole) and poly(N-ethylcarbazole) powders were chemically synthesized by the reaction of ceric ammonium nitrate (CAN) with N-vinylcarbazole carbazole and N-ethylcarbazole in acetonitrile. Products were characterized by elemental analysis, Fourier transform infrared spectroscopy, scan…
ABSTRACT Equilibrium vapor pressures of allyl isothiocyanate (AIT) above pure AIT and AIT/canola oil mixtures from 15 to 45°C were estimated from AIT vapor densities using gas chromatography. Canola oil was an effective diluent for depressing AIT vapor pressure. Permeation of AIT in a PVDC/PVC copolymer film was measu…
The influence of sulfate‐reducing bacteria (SRB) on the passivity of type 304 austenitic stainless steel was investigated using x‐ray photoelectron spectroscopy (XPS) and electrochemical techniques. Multiple samples were exposed to a SRB culture, Desulfovibrio desulfuricans , and then resultant changes in the surface…
The silicone-based formulations now in use by Raychem have been specially developed for electrical insulating applications. They have undergone many years of development and optimization to yield exceptional electrical and weathering performance properties, comparable to the polyolefin copolymer materials. The intent…
Short unbranched alkanes, such as heptane and hexane, prefer extended conformations. Polythene chains prefer folded conformations. How long a chain can be built before the global minimum conformation ceases to be linear? The question is a difficult one, because exhaustive conformation searches on molecules of the size…