Materials Literature
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Chromium chrysoberyl undergoes a phase transformation from a paramagnetic state to a complex antiferromagnetic state at 28 K. The spiral spin structure of the antiferromagnetic state violates all the crystallographic symmetry elements, making Cr2BeO4 potentially ferroelectric. Chynoweth experiments conducted at low te…
Abstract Ten chitosan products were manufactured from dry shrimp hulls under differing process conditions and compared to a commercially available product. Manufacturing variables tested were: alkali versus enzymatic deproteination; acid demineralization versus no treatment; air versus nitrogen atmosphere; 5 min vs. 1…
The high yield of secondary electron emission from insulators due to electron bombardment may be the result of an increase of the depth of escape. The free-electron scattering theory is applied to the high energy of the primary beam, but it cannot be applied to the low energy of the secondary escaping beam because of…
Results are presented which show that the flatband potential ( V fb ) of a semiconducting cadmium sulfide ( CdS ) photoanode can be predicted from atomic electronegativity of its constituent atoms. This procedure, previously applied only to metal oxides, now appears generally applicable to any semiconductor‐electrolyt…
Expressions are derived for the effect of penny-shaped cracks of various orientations on the thermal conductivity of solid materials.
Single-crystal neutron-diffraction data with full-matrix least-squares refinements have yielded precise locations for all atoms (for the H atoms in particular), in both compounds. Hydrogen bonding with H atom sites disordered with equal occupancy, as previously postulated to be the source of zero-point entropy in the…
Solvent makes a significant contribution to the diffracted intensity of crystals and fibres of large biological molecules. Allowance for this contribution must be made in the refinement of trial structures and an improved method is described for the calculation of solvent scattering.
Ein allgemeines Strukturprinzip für organische Verbindungen, die zur zweistufigen Elektronenübertragung befähigt sind, geht aus der folgenden Reaktionssequenz hervor: Dabei können ein oder beide X durch Y⊖ ersetzt sein. In diesen Systemen besitzt der radikalische Partner oft sehr große thermodynamische Stabilität. Wah…
Abstract A new, fast, and simple method based on size exclusion chromatography permits determination of the volumes of open and closed pores of rigid solids such as silica or porous glasses, together with the specific surface and the pore‐size distribution for pore diameters ranging from 10 to 4000Å. The results are i…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structure and redox properties of the clusters [Ru3O(CH3CO2)6L3]n+John A. Baumann, Dennis J. Salmon, Stephen T. Wilson, Thomas J. Meyer, and William E. HatfieldCite this: Inorg. Chem. 1978, 17, 12, 3342–3350Publication Date (Print):December 1, 1978Publication Hist…
Some dielectric materials with large densities of low-mobility charge carriers show an anomalous low-frequency dispersion of the real and imaginary components of the complex dielectric permittivity, both varying as ω n−1 , with n close to or equal to zero. This behaviour is likely to be found in any dielectric materia…
La crisis de la energía, que tomó gran importancia a partir de 1973, ha originado la aceleración de estudios y posibilitado el desarrollo de otras fuentes alternativas del petróleo. El aprovechamiento de la energía latente que tienen algunos materiales volcánicos, o subproductos de procesos industriales (escorias side…
Para apreciar la acción física de microfisuración que experimentan los hormigones, cuando se encuentran sometidos a esfuerzos de compresión, se emplean en la actualidad diversas técnicas, siendo las más utilizadas la prospección radiográfica, los métodos fotoelásticos, y la observación mediante microscopía.
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El Pliego de Prescripciones Técnicas Generales para la Recepción de Cementos (RC-75), Decreto 1.064/1975 de 23 de mayo de 1975, publicado en los B.O.E. núms. 206 y 207, de fechas 28 y 29 de agosto, respectivamente, del mismo año, incluye la clasificación de los cementos, las prescripciones relativas a las característi…
A theory is presented in which the elimination of charging artefacts on uncoated insulating surfaces in the scanning electron microscope by a low-pressure ambient gas is taken to be due to ionisation of the gas. Curves of ion current against ionising field calculated from a model of gas neutralisation give good agreem…
We extend the scope of the Mueller calculus to parallel that established by Jones for his calculus. We find that the Stokes vector S of a light beam that propagates through a linear depolarizing anisotropic medium obeys the first-order linear differential equation dS/dz = mS, where z is the distance traveled along the…
A study of the electrical conductivity of the halogen doped transpolyacetylene system, (CH)x, is reported. When films of trans- (CH)x are exposed to chlorine, bromine, or iodine vapor, uptake of halogen occurs; and the conductivity increases markedly, over eleven orders of magnitude in the case of iodine. The behavior…
Abstract Raman spectra of anatase have been observed in natural and synthetic crystals. Both crystals show the same spectral features. The Raman band occurring at 516 cm −1 at room temperature is split into two peaks centred at 519 cm −1 and 513 cm −1 at low temperature (73 K). The six Raman active fundamentals predic…