Materials Literature
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Abstract Dry grinding of pyrophyllite (Hillsboro, USA) has been studied by X-ray diffraction (XRD), specific surface area measurements (BET) and scanning electron microscopy (SEM). At the beginning of the grinding process, some effects such as delamination, gliding and folding of the layers, and decrease in particle s…
The present work investigates the acoustical absorption and scattering cross sections of spherical bubble clouds subject to harmonic farfield pressure excitation. Bubble dynamics effects and energy dissipation due to viscosity, heat transfer, liquid compressibility, and relative motion of the two phases are included.…
Abstract Diffusion of K during analytical electron microscopy (AEM) results in anomalously low count rates for this element. As the analysis area and specimen thickness decrease, count rates become disproportionally lower. Adularia and muscovite show different diffusion profiles during AEM; for muscovite a strong depe…
Monosized, spherical Y 2 O 3 was processed from raw commercial Y 2 O 3 by homogeneous precipitation in aqueous solution via urea decomposition. Dry‐pressed pellets of the synthesized and raw powders were sintered to 1500°, 1600°, and 1700°C for 7 to 720 min. Microstructural development was followed with scanning elect…
Abstract Pillared smectites in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties. Several possible routes by which such materials might be made have been investigated, namely intercalation of hydroxy-Fe(III) polycations, mixed hydroxy-Fe(III)/Al polycations, phena…
Abstract Nonlinear optical properties of semiconductor‐doped glasses are reviewed. A growth technique enabling to obtain semiconductor microcrystals with controlled sizes grown in a glassy matrix is described. It is shown that the optical properties of such systems are determined by the energy spectrum of the electron…
Diffusion and reaction in porous heterogeneous catalysts has been a subject of intensive investigation for almost half a century. Major summary works were published by Wheeler in 1951 and 1955 [1, 2], by Satterfield and Sherwood in 1963 [3], by Satterfield again in 1970 [4], and by Aris in 1975 [5, 6]. Recent years ha…
Abstract The effects of dry grinding on the structure of sepiolite were studied by XRD, surface area measurement, TG-DTA and IR spectroscopy techniques. The results show that the sepiolite framework is rather resistant to mechanical stress and its alteration by dry grinding occurs through three successive, overlapping…
The relative photoionization cross section of atomic oxygen for the production of singly charged ions has been remeasured in more detail and extended to cover the wavelength range 44.3--910.5 A\r{} by use of synchrotron radiation. In addition, the contribution of multiple ionization to the cross sections has been meas…
Soil humic substances were extracted with dipolar aprotic solvents in mixture with dilute HCl, by an intermolecular H-bond-disruption mechanism, and their chemical and physical-chemical properties were compared with humic acids obtained with NaOH and Na4P2O7 solutions. The effects of the HCl-HF purification treatment…
Optical studies have been carried out on a nematogenic copper complex, which incorporates the features of both rod-like and disk-like molecules. Conoscopic figures are presented demonstrating (i) the occurrence of a biaxial nematic phase in the pure complex, (ii) the uniaxial-biaxial (Na-Nb) transition in binary mixtu…
Since the discovery of liquid crystals one hundred years ago, reentrant phase transitions have transformed from being isolated curiosities to an established phenomenon. A significant influence for this change in point of view, has been the almost overnight discovery of the many reentrant transitions in liquid crystals…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHindered diffusion of water-soluble macromolecules in membranesMarc G. Davidson and William M. DeenCite this: Macromolecules 1988, 21, 12, 3474–3481Publication Date (Print):December 1, 1988Publication History Published online1 May 2002Published inissue 1 December 1988https:/…
When the grain size in partially sintered compacts of alumina was measured as a function of density, we found that the grain‐growth behavior fell into two distinct regions. In the region where the porosity remained interconnected, grain growth was negligible; when the continuous pore network collapsed into isolated po…
The main families of compounds able to produce lyotropic or thermotropic smectic and columnar mesophases have been presented. Their molecules have been considered as being formed of two distinct parts, incompatible with one another, covalently bonded, but suitably separated in space. Their liquid crystalline structure…
Phthalocyaninatoiron (FePc) complexes may be prepared inside the pore structure of large pore zeolites X or Y by a process of sequential introduction of components followed by assembly inside the void space of the zeolite. Such species are capable of performing as catalysts in the oxidation of alkanes using iodosobenz…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStatistical properties of the poly(N-vinylcabazole) chain as estimated from an NMR analysis of 2,4-bis-N-cabazolylpentaneAkihiro Abe, Hideyuki Kobayashi, Tokiji Kawamura, Masazumi Date, Toshiyuki Uryu, and Kei MatsuzakiCite this: Macromolecules 1988, 21, 12, 3414–3419Publica…
An unusual complex with planar Mo8 eight-membered ring, the title compound 1, is formed by insertion of the CO groups of rhodizonic acid (cyclo-C6(O)4(OH)2) into MnO bonds. The acid is subsequently degraded to oxalate (C atoms white), which remains in the cavity (the eight terminal CH3 groups are not shown).
The Cahn-Hilliard equation, which is important in the context of first-order phase transition, has frequently been studied in its simplified form, <disp-formula content-type="math/mathml"> \[ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="c Subscript t Baseline equals normal upper Delta left-bracket…
Abstract The weathering of a trachytic pumice within a pyroclastic flow underlying an andic-brown soil on the volcano Vico has been studied. The main mineral formed is a spherical 10 Å halloysite which has been shown by SEM and in situ microprobe analysis to have formed directly from the glass. The major mineralogical…