Materials Literature
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Stress enhancement due to the migration of charges can be a critical factor in the design of solid insulation for high voltage DC systems. The effect of bulk currents on surface and internal charge accumulation is discussed; and equations are formulated which predict steady-state conditions in arbitrary configurations…
The extremely hydrolysis-sensitive compound (BS2)8, obtained by fusion of a mixture of B2S3 and S8 in vacuo (300/100°C), has been found by X-ray structure analysis to be a planar porphine analogue. A second synthetic route starts from pre-formed five-membered rings.
Polyethylene consists of crystalline parts and amorphous parts. Trap sites for electrons or ions exist on a boundary between them. Mechanical drawing or isothermal crystallization of a bulk from its melt provides increased trap sites due to change of morphology in crystalline lamellae. The trap sites for electrons mig…
Electrode kinetics of fuel oxidation on nickel and cobalt electrodes is discussed for three selected molten carbonate mixtures. The measurements were made using a potential step technique. The highest exchange current values were found on nickel anodes in all melts, and the highest of these values were found in the me…
Abstract Glauconite has been synthesized at low temperature by precipitation of Fe-hydroxides from Si-, Fe-, Al-, and K-containing solutions under reducing conditions. The compositions favorable for the synthesis at 20°C and pH 8.5 are 1 ppm Fe, 0.15 ppm Al, 13 ppm Si0 2 , 1000 ppm KC1, and 1000 ppm dithionite. The K-…
A number of materials which exhibit the relatively new discotic phase have recently been discovered. All of the materials known which show this type of phase have molecular structures that are flat and hexagonal in shape. In this current work, we have shown that a porphyrin compound, uro-porphyrin I octa-n-dodecyl est…
Steel corrosion has been investigated through polarization studies in aqueous systems of acid p H using a rotating disk electrode cell. does not change the Tafel slopes of the anodic and cathodic processes. The anodic curves are shifted toward more negative potentials mainly due to the decrease of the reversible poten…
Jack C Burfoot and George W Taylor 1979 London: Macmillan viii + 465 pp price £20 The authors have concentrated on ferroelectrics, polar materials which undergo a spontaneous polarisation capable of modification by an electric field. The first and rather larger part of the book is a basic treatment of the electrical,…
Graded-index antireflection (AR) surfaces can be developed on phase-separated optical-quality glass. These surfaces have a median damage threshold of 12 J/cm2 for 1-ns, 1.06-μm laser pulses which is 2.5 times higher than the threshold of thin-film AR coatings, and reflectivity ≲0.2%, comparable to thin-film coatings.
Senescence of isolated petals of Tradescantia is accompanied by a large increase in membrane permeability, and application of ethylene hastens the onset of this increase. There is a 1- to 2.5-hour lag between ethylene application and the onset of anthocyanin efflux (an indicator of increased membrane permeability). Si…
The atomic coordinates and the anisotropic thermal parameters of CsH 2 PO 4 crystal in the paraelectric phase have been obtained using three-dimensional X-ray intensity data collected by a four-circle automatic diffractometer at room temperature. The structure is refined to R =0.029 for 780 independent reflections. Tw…
Oxidation state changes, completeness of oxidation, and densities of anodically formed, electrochromic iridium oxide films have been determined by combined gravimetric, coulometric, and reflection spectroscopy analyses. The results show that the oxidation state of Ir ions in the oxide is changed from III to IV during…
The temperature dependence of the dielectric susceptibility and the loss-peak frequency in dipolar materials has been examined using tlie cooperative, many-body, theory proposed earlier. A set of fundamental relationships between the behaviour of the loss-peak frequency and the magnitude of the sueeptibility are deriv…
Abstract Two variables must be considered when calculating exchange free energies (ΔG°ex) for 2:1 clays: (1) anionic field strength, as expressed by equivalent anionic radius (r a ), and (2) interlayer water content, as expressed by interlayer molality. For smectites that are in a state of high hydration, interlayer m…
Abstract Thermal conductivities of six oriented semicrystalline polymers which range from 0.37 to 0.63 in crystallinity and 1 to 5 in draw ratio λ (up to about 15 for two polymers) have been measured between 100 and 340 K. It was found that for increasing λ the conductivity K ∥ (along the draw direction n̂ ) increases…
Abstract Thermally reversible jellies of optically active 12-hydroxyoctadecanoic acid (12HOA) with CCl4 or aromatic solvents form a lyotropic mesophase, which shows enantiomeric circular dichroism (CD) and induced CD due to achiral molecules added to the jellies, indicating that the jellies have a supramolecular helic…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe electronic spectrum of tris(2,2'-bipyridine)ruthenium(2+)Franz Felix, James Ferguson, Hans U. Guedel, and Andreas LudiCite this: J. Am. Chem. Soc. 1980, 102, 12, 4096–4102Publication Date (Print):June 1, 1980Publication History Published online1 May 2002Published inissue…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of autoxidation of iron(II) porphyrins. Detection of a peroxo-bridged iron(III) porphyrin dimer and the mechanism of its thermal decomposition to the oxo-bridged iron(III) porphyrin dimerDer-Hang Chin, Gerd N. La Mar, and Alan L. BalchCite this: J. Am. Chem. Soc. 1…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and characterization of "tailed picket fence" porphyrinsJames P. Collman, John I. Brauman, Kenneth M. Doxsee, Thomas R. Halbert, Edward Bunnenberg, Robert E. Linder, Gerd N. LaMar, John Del Gaudio, George Lang, and K. SpartalianCite this: J. Am. Chem. Soc. 1980, 10…
The fine structure of the several layers and regional specializations in the Drosophila melanogaster eggshell has been studied by a combination of shell isolation procedures and ultrastructural techniques (conventional TEM, whole-mount TEM, SEM, HVEM, freeze-fracture electron microscopy utilizing rotary replication, s…