Materials Literature
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Measurements of n- and p-type porous silicon indicate no direct correlation between particle size and photoluminescence (PL) energy. Controlled continuous removal of silicon does not result in a continuous PL blueshift, which would be expected in the quantum confinement model. Also, high temperature (1200 °C) anneals…
At least twenty-seven proteins belong to the XylS/AraC family of prokaryote transcriptional regulators. All members of this family except CelD and TetD are positive transcriptional factors. Three subgroups were distinguished within the family in accordance with the Needleman and Wunsch algorithm. Multiple alignment of…
We have stulied the structure and intrinsic magnetic properties of R2Fe17C compounds (R = Y, Sm, Gd, Tb, Dy and Er), and compared them with the corresponding R2Fe17 compounds. The Curie temperatures of R2Fe17C are about 200K greater than those of R2Fe17. We discussed the variation of the structure and magnetism of the…
M agnetic anisotropy of a nanocrystalline Fe73.5Cu1Nb3Si13.5B9 soft magnetic alloy was investigated. Theoretical analysis and measurement results show that the effective magnetic anisotropy constant in the nanocrystalline alloys can be measured by means of the process of approaching saturation and the measured value i…
Electropolishing of metals and numerous alloys may provide, smooth, bright, and reflective surfaces that exhibit superior corrosion resistance compared to untreated metals. These features are achieved mainly in electropolishing of pure metals and single–phase alloys. Past works have indicated that in comparison with d…
Abstract X-ray diffraction analyses were applied to various pure nickel substrates while exposing them to oxygen at temperatures up to 800 °C. Coefficients of thermal expansion (CTE) were calculated from lattice parameters for both the nickel and the growing surface oxides. Behaviors more complex than the case for sin…
The electrical resistivity ρ and the thermoelectric power S of Mn 2−x Co x Sb(x≦0.3) are studied. The abrupt change of ρ and S (0<x) appears near the temperature of magnetic order-order transition. S of Mn 2–x Co x Sb (0≦x≦0.3) is positive in the ferrimagnetic region and negative in the paramagnetic region. we have…
Abstract Die Reproduzierbarkeit der Synthese von Poly(p‐phenylen‐1,3,4‐oxadiazolen) in Oleum Kann durch eine veränderte Monomerzugabetechnik, gemessen an der Standardabweichung der relativen Lösungsviskosität, um eine Größenordunung verbessert werden. Die Polykondensation verläft unter deutlich milderen Bedingungen in…
Abstract This article describes the factors considered in the analysis of brazeability and solderability of engineering materials. These are the wetting and spreading behavior, joint mechanical properties, corrosion resistance, metallurgical considerations, and residual stress levels. It discusses the application of b…
Gaseous impact testing has been accomplished in assorted ways dating back to at least the 1950s. ASTM Committee G-4 grappled with disparate views and melded them into ASTM G 74 in 1982. Criticized for being both too sensitive and too insensitive, recent data has unfortunately also led to calls for the test's abandonme…
グリコールを主とする化学的処理方法によって廃棄硬質ポリウレタンフォームが分解された. IRとGPCの分析により, 分解生成物は多量の反応性ポリウレタンオリゴマーを含むことが認められた. アミン/グリコール比・反応時間の増加, 反応温度の上昇は, 反応生成物の水酸基価・アミン価の増加と粘度の低下をもたらす. この分解生成物を直接エポキシ系接着剤の硬化剤として利用するため, キュア条件, 分解生成物/エポキシ樹脂比, 通常のエポキシ接着剤系で使用されているアミン硬化剤・添加物との併用などが検討された. その結果, 廃棄硬質ポリウレタンフォームの分解生成物はエポキシ系接着剤の接着強度を高めることが認められ, その有用性が明らかとなった.…
Abstract The magnetoplumbite crystal LMA is grown by the CZ technique. The orientations of all developing facets on the crystals are determined by means of X‐ray and optical methods, and Miller indices are calculated. According to the PBC theory, the relations between the morphology of LMA crystal and its structure ar…
Abstract When CdS and related II‐VI direct bandgap materials form semiconductor clusters in which the absorbance properties are dominated by quantum size effects, the emission properties are particularly sensitive to surface defects, which are associated with the unfilled valence of surface Cd 2+ ions. These mid‐bandg…
With this issue a new Section of Acta Crystallographica, one devoted to biological crystallography, is initiated.The determination of crystal structures of biological macromolecules provides a wealth of information that makes this area of crystallography highly significant, exciting, and of general interest to a wide…
When tetrapropylammonium cations are removed from the α cavities of SAPO 37, but tetramethylammonium cations are still in the β-cages, a shift in the vibrational frequency of hydroxy groups to lower frequencies, with the corresponding appearance of stronger acid sites is observed; this is a consequence of the increase…
Abstract The new quaternary sulfides Ba 2 LaAg 5 S 6 and Ba 2 YAg 5 S 6 have been synthesized by the reaction among BaS, La 2 S 3 or Y 2 S 3 , Ag, and S at 1000[unk]C. The crystal structure of Ba 2 LaAg 5 S 6 has been determined by X-ray diffraction techniques. Crystal data: space group C 2/ m , M = 1145.3, Z = 2, a =…
A thousand thermal cycles of vanadium hydride across the β-γ mixed phase region decreased the reversible hydrogen storage capacity and increased the absorption/desorption pressure hysteresis ratio. Thermal cycling also produced a large increase in hydride surface area. Nevertheless, X-ray diffraction and transmission…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDeposition and characterization of polyimide Langmuir-Blodgett filmsKarl F. Schoch Jr., Wei Fang A. Su, and Mary Grace BurkeCite this: Langmuir 1993, 9, 1, 278–283Publication Date (Print):January 1, 1993Publication History Published online1 May 2002Published inissue 1 Januar…
The salts [Co(η6-C6Me6)2]+[A]–(A = BPh4, NbF6, PF6 or SbF6) have been prepared from anhydrous CoCl2. Solid-state magnetic susceptibility measurements on these salts indicate that they all obey the Curie–Weiss law in the temperature range 30–300 K with µeff= 2.7, 2.8, 2.8 and 2.6 µB with corresponding θ values of –1.4,…
An earlier paper showed that dezincification of [alpha]-brass could be monitored electrochemically by simulating the solution that would develop in an anodically polarized cavity and then carrying out a test in this solution at zero volts vs a copper reference electrode. A prediction made from the earlier work was tha…