Materials Literature
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High-resolution neutron and X-ray diffraction data for vitamin B~2 coenzyme have been obtained with the objective of elucidating the water organization in this crystalline system. Here, details of the data collection and refinement of the individual models are described. Neutron data: Mr = 1939 (assuming exchange of 1…
The fracture initiation and arrest stress intensity factors were determined for a SiC‐whisker‐reinforced AI 2 O 3 matrix composite. A chevron‐notched, three‐point‐bend specimen was used to genera e the load/displacement curve, which exhibited repeated crack initiation, followed by crack arrest behavior. Corresponding…
Abstract Aromatic polyesters and polyamides with disc‐like mesogens in the main chain were prepared from tetra‐substituted hydroquinones and derivatives of 1,4‐phenylenediamine. Depending on the atomatic acids (terephthalic acid, 2,5‐dialkoxyterephthalic acid) used in the condensation reaction, the repeating units of…
A procedure was developed to purify large quantities of PII protein from an Escherichia coli strain which contains a multicopy plasmid harboring the structural gene of PII (the glnB gene). Ultraviolet spectra of uridylylated and unuridylylated PII were obtained using the purified PII and empirical formulas to calculat…
Large area chemical vapour deposition of diamond has been obtained using magneto-microwave plasma. The important point of the developed system is to set the electron cyclotron resonance condition (875 G), where the highest plasma density is expected, at the deposition area by controlling the distribution of an applied…
The infrared spectra of several type Ia diamond crystals expected to contain voidites have been examined in the wavenumber range 4000–2700 cm−1. The absence of any absorption which could possibly be attributable to the stretching of N─H bonds makes unlikely recent suggestions that the voidites may contain a solid phas…
Abstract Versuche, von Dimethylphenyl‐2‐tolylsilan ( 5 ) oder 2‐Brombenzoesäure ausgehend über 2‐(Dimethylphenylsilyl)benzoylchlorid ( 11a ) mit Zinntetrachlorid als Ringschlußkatalysator zu 9,9‐Dimethyl‐9‐sila‐10(9 H )‐anthracenon ( 4a ) zu gelangen, führten stets in hohen Ausbeuten zur Titelverbindung 14a , deren Ko…
Abstract Five paraffins (C30–C44) and three linear compounds with polar end-groups, such as hydroxyl, methyl-ester, and carboxyl groups, were deposited on the cleavage surface of an alkali halide crystal in vacuo. Paraffin films deposited on the substrate took the same crystal structure and molecular orientation, inde…
A b initio crystal orbital calculations on the oxidized form of polyaniline with alternating benzoid–quinoid structure are reported. For two possible configurations, the trans and the cis isomer, the twist angle between nearest neighbor rings is optimized with respect to the total energy per elementary cell. It turns…
The structure of the omega-phase which is formed by the quenching of Ti-14 wt%Mo alloy from 1223 K to 273 K was investigated at the atomic level using a high-resolution electron microscope (HREM). The HREM image were formed by using 15 diffracted waves including diffuse scattering due to the omega-phase. The focus of…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermochemistry of inorganic solids. 7. Empirical relations among enthalpies of formation of halidesMohamed W. M. Hisham and Sidney W. BensonCite this: J. Phys. Chem. 1987, 91, 13, 3631–3637Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Pu…
A design is given for a powder diffractometer on a synchrotron source. A reasonable balance between resolution and luminosity is achieved by making the effective mosaic spread parameters of the monochromator and analyser crystal equal to the vertical divergence of the synchrotron beam. A monochromator with a Bragg ang…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTemperature-dependent changes in the structure of the amorphous domains of semicrystalline polymersMarc L. MansfieldCite this: Macromolecules 1987, 20, 6, 1384–1393Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Published inissue 1 June 198…
Electrical breakdown strength of paper-oil insulation samples was meas ured under dc, ac and pulsating voltages. The latter was obtained by superimposing ac upon dc voltage and provides an attractive method for a simultaneous testing and assessment of the state of insulation of the various parts of HV apparatus in ser…
Three different alloys of AISI Type 444 (18Cr–2Mo) ferritic stainless steel, stabilized to different levels with titanium and/or niobium, were melted as welds or weld simulations with deliberate additions of nitrogen to the argon shielding gas in order to simulate the effects of accidental contamination by nitrogen du…
The following fifteen reference patterns of boride, silicide and oxide ceramics represent the first group of ceramic phases measured at the National Bureau of Standards under the project “High Quality Reference Patterns and Total Digital Powder Patterns of Technologically Important Ceramic Phases”. The support and int…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelective steroid chlorinations directed by attached pyridine ester templatesRonald Breslow, Michael Brandl, Juergen Hunger, and Alan D. AdamsCite this: J. Am. Chem. Soc. 1987, 109, 12, 3799–3801Publication Date (Print):June 1, 1987Publication History Published online1 May 2…
The influence of the metal-dielectric junction on the electric field distribution along the solid insulator-vacuum interface is analyzed in detail in two widely used electrode-insulator geometries: (1) a cylindrical solid insulator with metal inserts at both ends and (2) a cylindrical solid insulator placed in recesse…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrostatic potentials and relative bond strengths of some nitro- and nitrosoacetylene derivativesPeter Politzer and Ruth Bar-AdonCite this: J. Am. Chem. Soc. 1987, 109, 12, 3529–3534Publication Date (Print):June 1, 1987Publication History Published online1 May 2002Publish…
Clostridium sporogenes was grown on alanine, glycine and alanine + glycine in pure culture and in syntrophic cultures with methanogens. Batch and continuous pure cultures of C. sporogenes grew only poorly on alanine as the sole amino acid, due to an elevated hydrogen partial pressure and converted alanine to acetate,…