Materials Literature
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Light scattering and viscosity measurements were made on anionically polymerized four-arm star polystyrene samples with weight-average molecular weights M w of 8.5 × 10 4 to 3.1 × 10 6 in cyclohexane at different temperatures to determine the mean-square radius of gyration 〈 S 2 〉, the second and third virial coeffici…
A compact 60 kV Mott polarimeter has been constructed, tested, and calibrated especially for the local analysis of surface and two-dimension magnetism by means of electron spectroscopy with spin resolution. The use of construction combining spherical accelerating field with the absence of retarding potential after ele…
The electron density distribution in lithium triborate LiB 3 O 5 has been studied at room temperature by X-ray diffraction using Ag K \alpha radiation up to 1.02 Å −1 [1439 unique reflections with I > 3\sigma( I )]. Conventional refinements with a free-atom model yield R ( F ) = 0.0223, wR ( F ) = 0.0299, S = 1.632…
The red shift of the fundamental absorption edge (≈︂0.16 eV) of a La0.9Sr0.1MnO3 single crystal occurs as the crystal is cooled into the ferromagnetic phase. This result shows that there exist spin-dependent states. The reflection and absorption spectra of La1—xSrxMnO3 single crystals (x = 0.1, 0.2, 0.3) indicate that…
Abstract Methyl‐substituted or unsubstituted aromatic dicarboxylic acids and diamines containing ether and sulfone linkages between phenylene units were used alone or in combination with p ‐phenylenediamine, m ‐phenylenediamine, terephthalic acid, and isophthalic acid to prepare flexible or semirigid aromatic polyamid…
Digital video microscopy is used to study the Brownian motion in quasibidimensional colloidal systems, consisting of spherical polystyrene particles suspended in water and confined between two glass plates. This technique allows the direct measurement of the lateral (two-dimensional) probability distribution function,…
This paper describes the preparation of new oxide host materials for Er 3+ based on GeO 2 by the sol‐gel method. The characterization of these new materials is reported, with particular regard to the crystallization behavior: the tendency of GeO 2 gels to crystallize during thermal treatment, in fact, is a critical pr…
The 1 H NMR spectra of iron(III) quinoxalinotetraphenylporphyrin ((QTPP)Fe III X n ), iron(III) (methylquinoxalino)tetraphenylporphyrin ((MQTPP)Fe III X n ), and iron(III) pyrazinotetraphenylporphyrin ((PTPP)Fe III X n ) have been studied to elucidate the impact of an aromatic extension of a single pyrrole ring on the…
Abstract Transformations of clay minerals were studied in a sequence of podzols (Entic Cryorthods) of increasing age (5500-10000 years BP) developed from till materials in central Finland. The age of the soils was estimated according to altitude above the present sea level, with reference to the age of ancient shoreli…
Four crystalline forms of isotactic poly(4-methyl-1-pentene) (i-P4MP) (forms I, II, II, and IV) have been studied through solid-state 13 C NMR CP-MAS spectroscopy. The assignment of the resonances observed in the 13 C NMR CP-MAS spectra was made by dipolar dephasing experiments. The presence in all spectra of two dist…
The structural, electronic and magnetic properties of spinel are investigated using the periodic ab initio Hartree - Fock program CRYSTAL. The geometry is fully optimized and the bulk modulus evaluated. The system is a large-gap insulator; the Mn - O bond is fully ionic, whereas in the Cr - O case there is a relativel…
The goal of this work has been to propose a novel approach to fine tune the transition temperatures of spin transition materials, based on the concept of spin transition molecular alloys. It has concerned the alloys of composition [Fe(R 1 trz) 3-3 x (R 2 trz) 3 x ]A 2, where R 1 trz and R 2 trz stand for two different…
The title complexes, (P•)FeIVO(Im) and (P•)FeIVO(OAr), have been prepared by the ozone oxidation of iron(III) porphyrins. The absorption spectra of (P•)FeIVO(Im) and (P•)FeIVO(OAr) are similar to those of compounds I of horseradish peroxidase and catalase, respectively. The NMR measurements of (P•)FeIVO(Im) show an a1…
Using a single-phase sample of ${\mathrm{Ce}}_{2}{\mathrm{Fe}}_{17}$ with the rhombohedral ${\mathrm{Th}}_{2}{\mathrm{Zn}}_{17}$-type structure, we measured the magnetization, resistivity, and specific heat under various magnetic fields up to 5.5 T. Below ${T}_{c}=125$ K, giant magnetoresistance (GMR) is induced by th…
Abstract Ni-Fe pyroaurite-type hydroxychlorides were prepared by aerial oxidation of Ni(II)-Fe(II) hydroxides precipitated in aqueous solution with various P = Fe/Ni ratios. When P ≥ 1/3, Ni(II)-Fe(II)-Fe(III) hydroxychlorides characterized by a specific Fe(IIl)/[Fe(II)+Ni(II)] ratio of 1/3, corresponding to the ideal…
Phase transitions and morphology of poly(diethylsiloxane) have been studied with help of differential scanning calorimetry and transmission electron microscopy on carbon−platinum replicas of freeze-fractured samples. The TEM experiments showed distinct lamellae in the case of the β and γ crystalline polymorphs, whose…
The γ-radiolysis of poly(tetrafluoroethylene- co -perfuoromethyl vinyl ether) (TFE/PMVE) was investigated using solid state 19 F and 13 C NMR spectroscopy. Chain scission products identified in the polymer were saturated chain ends −CF 2 CF 3 ( G = 1.0), methyl ether end groups −CF 2 OCF 3 ( G = 0.9), acid end groups…
Perovskite lead scandium tantalate (PST)—PbSc1/2Ta1/2O3—thin films have been prepared from lead-rich targets by rf magnetron sputtering onto a variety of substrates (e.g., MgO-on-sapphire and platinized silicon). Detailed microstructural chemical analysis of the films using transmission electron microscopy and energy…
The Bacillus subtilis araR locus (mapped at about 294 degrees on the genetic map) comprises two open reading frames with divergently arranged promoters, the regulatory gene, araR, encoding a repressor, and a partially cloned gene, termed araE by analogy to the Escherichia coli L-arabinose permease gene. Here, we repor…
Measurements of sonoluminescence from isolated cavities that spontaneously form on solid objects in a fluid-filled acoustic resonator are reported. The subnanosecond light flashes have a smooth ultraviolet spectrum similar to that from single bubbles, although with organic liquids low intensity Swan lines ride on the…