Materials Literature
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Abstract Overall and detailed kinetic descriptions of the pyrolysis of C 3 H 8 have been proposed as a result of a turbulent flow reactor investigation in the temperature range of 1110–1235 K and at atmospheric pressure. The overall reaction was described by a first‐order rate expression with an activation energy of 5…
The mineral monazite, a mixed lanthanide orthophosphate $\mathrm{Ln}\mathrm{P}{\mathrm{O}}_{4}$, is considered as a perfect host for geologic disposal of actinides, rare earths, and possibly other elements formed during nuclear-reactor operation. Synthetic monazite-type orthophosphates of all the elements of the first…
<div class="htmlview paragraph">Diesel engine particulates collected on a trap cause the exhaust back pressure to increase and adversely affect fuel economy and vehicle performance. Therefore, a trap must be periodically regenerated by oxidizing the collected particulates. Several techniques for regenerating a D…
Abstract Samples of nacrite, dickite, kaolinite, and halloysite were investigated using X-band electron paramagnetic resonance (EPR) and Mössbauer spectroscopy. Fe 3+ gave rise to EPR signals at g ≃ 4 which differed with the individual polytype. Only nacrite had no resonance in this region of the spectrum, but it had…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDivalent lanthanide chemistry. Preparation of some four- and six-coordinate bis[(trimethylsilyl)amido] complexes of europium(II). Crystal structure of bis[bis(trimethylsilyl)amido]bis(1,2-dimethoxyethane)europium(II)T. Don Tilley, Allan Zalkin, Richard A. Andersen, and David…
Nylon 6 yarns were wound at speeds varying from 700 to 5500 mpm. The effect of the winding speed on both α- and γ-type crystals in these undrawn yarns was studied. Also the effects of dry heat, tension, and heating in saturated steam were included in this investigation, since they provide useful information for drawin…
Epitaxial layers of In0.53Ga0.47As lattice matched to InP substrates have been grown by molecular beam epitaxy. The (100) InP substrate surfaces were first oxide passivated and then thermally cleaned under 1.5×10−6 Torr of arsenic moleuclar beam exposure (i.e., 1.24×1014 As4/cm2 sec). When they were heated to 500 °C,…
Electrochemical etching of Al with alternating current produces a high density of cubic etch pits covered with a film of oxide or hydroxide. Micrographs of the metal and film structures are presented and a model is proposed to explain the observations. Calculations demonstrate the feasibility of film deposition from a…
EPR and magnetic susceptibility of potassium perchromate (K3CrO8) have been studied from liquid helium temperatures to 400 K. EPR spectra of dilute aqueous solutions of K3CrO8 yielded giso=1.9712±0.0005, and 53Aiso=(18.6±0.5)×10−4 cm−1. The (positive) sign for 53Aiso, deduced here from the dependence of the linewidths…
We demonstrate the role and utility of lateral heat flow in the growth of single-crystal silicon islands on amorphous substrates. The thermal profile is varied on and around the islands by controlling the optical absorption using various thin-film structures. In this way, competitive nucleation from edges is suppresse…
In the course of preparing specimens for scanning electron microscopy, both glutaraldehyde and OsO4-fixed cells exhibit a considerable shrinkage with a reduction of the mean cellular diameter of about 45% after critical point drying. However, if cells are successively treated with glutaraldehyde, OsO4, tannic acid and…
<div class="htmlview paragraph">Emissions results are presented from an experimental study of an indirect injection diesel engine. The mass measurements of particulate emission are correlated with the measurements of smoke and HC emission. The correlation provides a less expensive way of carrying out preliminary…
The urea-induced unfolding of the alpha subunit of tryptophan synthase from E. coli was monitored by optical spectroscopy and by urea-gradient gel electrophoresis. Three independent lines of evidence support the conclusion that one or more stable intermediates are present in this process: (i) Satisfactory fits of the…
Experimental results and a theoretical model are presented which give strong evidence that the ratio β/L2μM is a constant for a large class of disubstituted conjugated hydrocarbons, β is the second-order polarizability, μM the mesomeric dipole moment, and L the length of the hydrocarbon chain.
Segments of yeast genomic DNA containing two enolase structural genes have been isolated by subculture cloning procedures using a cDNA hybridization probe synthesized from purified yeast enolase mRNA. Based on restriction endonuclease and transcriptional maps of these two segments of yeast DNA, each hybrid plasmid con…
Utilizing field data obtained in Part I, laboratory studies to simulate flashovers on several insulator shapes and designs were carried out. Chemical composition of the contaminants used in these studies was based on our findings at the Sylmar HVDC Converter Station. The flashover characteristics thus derived are comp…
Abstract The structure of thermally denatured Type I collagen has been studied using laser light scattering. The results indicate that the diffusion coefficients of α‐chains and β‐ and γ‐components are 1.550 ± 0.08 × 10 −7 , 1.000 ± 0.05 × 10 −7 , and 0.835 ± 0.04 × 10 −7 cm 2 /sec, respectively, at temperatures betwe…
Abstract The chemisorption of SO 2 on a W and a Pt surface has been investigated by flash desorption mass spectrometry (FDMS) and AES. AES data indicate that the chemisorbed sulfur dioxide molecules oxidized the W surface, and produced a stable tungsten oxide during the heating (up to 1400 K) process. FDMS data indica…
SUMMARY Two devices for measuring the beam current in an electron microscope are described; a Faraday cage rod for accurate absolute measurements in the specimen position and a collector plate mounted in the viewing chamber, which may be used continuously during experiments, for relative current measurements. Results…
It is well established that diffusion and relaxation processes in polymers above Tg are closely related in that they are both governed by the polymer segmental motions, which are believed to be determined by the free volume present in the system. The diffusion coefficients of gases in elastomers can be accounted for b…