Materials Literature
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The non-linear optical properties of semiconductors are reviewed. Examples are given of optical non-linearities which are connected with real or virtual excitations in the electronic system of a semiconductor, and others which are due to photothermal effects. Also included are some aspects of electro-optics, and the a…
Abstract The action of two vapour phase inhibitors (VPI), dicyclohexyl‐ammonium nitrite (DICHAN) and dicyclohexylamine (DICHAMIN), on the atmospheric corrosion of mild steel at a relative humidity of 100% and under isothermal conditions (25 °C) has been studied. In order to obtain electrochemical data with thin adsorb…
During the oxidation of redued single crystals of Al‐doped rutile, unusual anisotropies in color‐boundary migration have been observed that are opposite to those predicted from published diffusion data. Analysis of the redox kinetics and of surface segregation (using ESCA and AES) shows that rapid transport of minorit…
Abstract Clay mineralogy and petrography of the Early to Middle Eocene succession of the Dammam dome, Saudi Arabia, comprising the Rus and Dammam Formations, were studied using X-ray powder diffraction, light microscopy, and scanning electron microscopy. These formations consist of alternations of dolomite, dolomitic…
A mathematical approach is presented to calculate and predict the strength of a false twist yarn spun by means of a single air jet, based on an idealized yarn structure model developed in an earlier paper. The strength of the wrapping fibers and the core fibers and the frictional resistance of slipping fibers in the c…
SUMMARY In the preceding paper the effect of the primary beam scattering on contrast in high‐pressure SEM techniques such as moist‐environment ambient‐temperature SEM and environmental SEM was examined. Here, the effect of the scattering of the emissive components on the image formation and contrast in high‐pressure S…
The degradation of the pulsed surface flashover performance of 99.9% pure polycrystalline alumina in an insulator-bridged vacuum gap, due to the mechanical grinding and finishing of the insulator is reported. The flashover characteristics of three different surface finishes—as-fired (0.8 μm), a ground surface (0.25 μm…
We observe bond-selective fragmentation of the nitrous oxide molecule upon site-specific 1 s excitation at either the terminal or the central nitrogen atom. Our results can be interpreted as a chemical "memory effect" where the fragmentation process memorizes the inital site of energy deposition. We empty a new "Zero…
Abstract Ultrasonic emission was found to accompany spherulitic crystallization of polymers from the melt. The source of acoustic waves was identified as an abrupt negative pressure release in regions of melt occluded by spherulites (weak spots) in the course of crystallization. The buildup of a negative pressure in o…
Numerous synthetic biomaterials have been developed as vascular substitutes. In vitro, ex vivo and in vivo studies have demonstrated that in animals, selected materials, i.e., Dacron and ePTFE (expanded polytetrafluoroethylene) grafts, are successfully incorporated in both the large and the small caliber host arteries…
Ceria‐ and yttria‐doped tetragonal polycrystalline zirconia ceramics were ground at temperatures as high as 1100°C. X‐ray diffraction revealed that the intensity ratio I (002) / I (200) increased (to as high as ∼4.5) compared with that from the as‐sintered surfaces (∼0.55). The enhancement in I (002) / I (200) at temp…
To clarify the foreign object damage (FOD) resistance of ceramics, chipping fracture mode and flexural fracture mode were investigated using several types of Si 3 N 4 and Sic. The critical velocity which is the threshold impact velocity of the projectile for chipping fracture and flexural fracture was determined. The…
Abstract Single crystals of optical quality of L‐arginine HCl · H 2 O and L‐arginine HBr · H 2 O with dimensions up to 80 × 60 × 30 mm have been grown from aqueous solutions by controlled evaporation at about 310 K. The isotypic crystals exhibit a quite similar behaviour with respect to morphological, pyroelectric, di…
We present new evidence that two electron traps observed in polycrystalline zinc oxide can be associated with complex intrinsic defects. One deep level, E1, can be assigned to an oxygen vacancy. The second deep level, E2, could consist of a cluster-type defect associated with oxygen vacancies. The two traps were chara…
Abstract Dissolution kinetics of sepiolite from Eskisehir (Turkey) have been investigated at various temperatures and particle sizes using dilute hydrochloric and nitric acids. Dissolution reaction rate constants were calculated and apparent activation energies were dependent on acid concentration. For both acids, app…
Abstract Mass sorption/desorption and volume dilation/consolidation measurements are reported for tetramethyl and hexafluoro polycarbonate samples in the presence of carbon dioxide pressures up to 900 psia at 35°C. These results are combined with previous results for bisphenol‐A‐polycarbonate. The combined sorption an…
Alumina was joined to Ti‐6AI‐4V alloy by active brazing. High reactivity between the Cu‐40Ag‐5Ti braze alloy and these materials led to the formation of interfacial reaction products. These products were characterized by transmission electron microscopy and electron microprobe analysis. A continuous layer, identified…
Abstract Thermotropic liquid-crystalline polyethylenimines with an ammonium halide moiety and those low-mass model compounds exhibited enantiotropically smectic phases. They were homeotropically aligned with the formation of an ammonium bilayer. The homeotropic structure of the liquid-crystalline polyethylenimine rema…
Photocatalytic activity of TiO2 in the oxidation by oxygen of formic acid is considerably enhanced by the presence of dissolved copper ions. The role of oxygen transfer between the gas phase and the slurry is examined. The kinetic results obtained in the absence of mass transfer limitations lead to a mechanism based u…
SUMMARY The mechanisms of electron beam scattering are examined to evaluate its effect on contrast and resolution in high‐pressure scanning electron microscopy (SEM) techniques reported in the literature, such as moist‐environment ambient‐temperature SEM (MEATSEM) or environmental SEM (ESEM). The elastic and inelastic…