Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Materials for high brightness cathodes are evaluated by defining a figure of merit, which is based on the Richardson–Dushman equation. By calculating the figure of merit of borides, carbides, nitrides, and some refractory metals, it is concluded that carbides of transition metals such as TiC, ZrC, TaC, and HfC are pro…
Solid-state 31P and 29Si n.m.r. spectroscopy has been used to characterise a number of heteropolyanion salts. A significantly larger chemical shift anisotropy was seen for the phosphorus in the dimeric P : Mo = 2 : 18 Dawson structure than for the P : Mo = 1 : 12 Keggin unit. Two inequivalent phosphorus sites are seen…
The preparation and spectroscopic data of FeTMP(ClO4)2[(1), TMP = 5,10,15,20-tetramesitylporphyrinato] are reported; the reaction of (1) with NaOMe–MeOH gave a new red species, (2), which is indicated to exist (a) as a symmetrically ligated complex with a vacant dx2–y2 iron orbital (1H n.m.r.)and (b) in the iron(IV) s…
Over the years, several mathematical models have been proposed for predicting the critical withstand voltage of polluted insulators, mainly based on the static arc voltage-gradient equation of the type E = Ai−n. The paper proposes a new mathematical model which is based on a dynamic arc voltage-gradient equation. Comp…
There are a few reports that Cu sulfides precipitate with the addition of Cu in the grain-oriented silicon steel, but the precipitates of Cu sulfides have not yet been well observed Thus, the observation of the precipitation of Cu sulfides is performed and the metallurgical effects of Cu addition on the grain-oriented…
Abstract The Rheometrics mechanical spectrometer has been employed in the parallel plate mode to study the rheological behavior of pure polypropylene resin and melts filled with 10, 20, 30, and 40 percent by weight glass fibers. Steady‐state shear data show that, for loadings above 20 percent fiber, increasing fiber l…
A quasi-isothermal method of operating an absorbed-dose graphite calorimeter is described in theory and practice. In contrast with the well-known quasi-adiabatic operation, which entails temperature increases during measurements, in the quasi-isothermal mode the temperatures of the different graphite bodies remain con…
A brief general description of differential scanning calorimetry is followed by a more detailed treatment of the quantitative aspects of three applications that have widespread usage in the polymer industry: (1) the glass transition; (2) heats of reaction (curing); and (3) crystallinity. Emphasis is placed on the true…
The template condensation of 2,6-pyridinedicarbaldehyde with ethylenediamine in the presence of Sm(NO3)3 gave a complex formulated as [Sm(C18H20N6O)(NO3)3]. The complex was recrystallised from water and the X-ray crystal structure determined by the heavy-atom method and refined by least squares to a final R value of 0…
Abstract Some features of the crystal structure of Cu(II) oxalate, which are relevant for the interpretation of unusual magnetic properties of the substance, are discussed. EXAFS and X‐ray powder diffraction results described by different authors are compared. The results of both the analytical methods complement each…
The synthesis and characterisation of some asymmetrical meso-substituted porphyrins, for studies in solar energy conversion, are described. Isomeric porphyrins (5) and (6) could be cleanly separated and distinguished by the number of 13C n.m.r. resonances for the pyrrole α-carbon atoms. Similarly, 13C and 1H n.m.r. sp…
The magnetic behavior of ${\mathrm{Y}}_{6}$${\mathrm{Mn}}_{23}$ is dramatically altered upon hydrogenation (or deuteration). In this study it has been found, by means of high-resolution powder diffraction and Rietveld refinement techniques, that the crystallographic structure is distorted from face-centered cubic ($\m…
Abstract
π-Radical cations of water-soluble zinc porphyrins have been formed by oxidation with Br˙–2 under pulse-radiolytic conditions. These π-radical cations decay with complex kinetics but the rate of decay was enhanced upon addition of colloidal RuO2·2H2O. For the π-radical cation derived from zinc tetrakis(4-sulphonatophe…
We report a study of the viscoelastic and elastic properties of a nematic liquid crystal as measured by static and dynamic light scattering. Experimental values are reported for the splay/twist/bend elastic and viscoelastic ratio as well as for the Mięsowicz viscosity ratio η1/η3 of APAPA in the nematic region as a fu…
Une néphéline de composition (□0.04K0.48Na0.48)Na3[Al0.99Si1.01O4]4 a été synthétisée à partir d'un mélange d'oxydes dans NaF fondu à 1 000 °C/1 jour. Pour mesurer les intensités avec un diffractomètre X automatique à monocristal, on a choisi un fragment cristallin présentant un rapport I(230):I(320) minimum. Après co…
We have studied the cholesterization of discotic and calamitic lyotropic ferronematics by addition of brucine sulphate. The techniques used are optical microscopy for the textures and X-ray diffraction for the structures. The results concerning the pitch and the rotatory power of oriented samples containing or not fer…
The first monoarene complexes of gallium(I) were obtained by reaction of Ga2X4 (X = Cl, Br), suspended in toluene, with hexamethylbenzene. In 1b, C-1 and C-4 of the arena ligand are shifted towards the GaI; 1b can thus be regarded both as a π-complex as well as nido-cluster.
The previous X-ray-crystallographic determination of the relative configuration of P-1894B, a potent prolyl hydroxylase inhibitor isolated from the culture broth of Streptomyces albogriseolus, was extended by means of chemical and spectral studies. The absolute configuration of P-1894B (1) was established from the abs…
Indium-tin-oxide single crystals with 0–9 atomic% of Sn/In are produced by flux method, and their electrical properties are measured. At about 2 atomic% of Sn/In, the resistivity is 2×10 -4 Ω-cm and the electron concentration is 3×10 20 /cm 3 at room temperature. Further increase of Sn/In ratio does not change the ele…