Materials Literature
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SUMMARY Potassium was extracted from samples of 21 surface soils and nine subsoils using a calcium‐saturated cation exchange resin and concentrated HCI under reflux. Most of the important arable soils of England and Wales were represented in the samples. The two methods permitted determination of the amounts and rates…
Abstract A series of polyurethane block copolymers based on hydroxybutyl terminated poly(chloropropylmethyl‐dimethylsiloxane) and poly(tetramethylene oxide) soft segments of molecular weights 2100 and 2000, respectively, were synthesized. The hard segments consisted of 4,4′‐methylenediphenylene diisocyanate (MDI) that…
The authors investigate optical bistability in CdS, induced by photo-electronic non-linearities. Varying the photon energy and the temperature of the sample they find three different types of optical bistability. The switching times are always around 1 ns or below, notably 300 ps for dispersive optical bistability. Op…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFunctionalized Keggin- and Dawson-type cyclopentadienyltitanium heteropolytungstate anions: small, individually distinguishable labels for conventional transmission electron microscopy. 1. SynthesisJohn F. W. Keana and Marc D. OganCite this: J. Am. Chem. Soc. 1986, 108, 25,…
Abstract The XPS peak shape from inhomogeneous transition metals is studied theoretically under variation of the path length R travelled by the photoelectron in the solid, the XPS peak energy E p , and the particular metal M . The variation in peak shape is characterized by a single parameter D = A p / B which is the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFunctionalized Keggin- and Dawson-type cyclopentadienyltitanium heteropolytungstate anions: small, individually distinguishable labels for conventional transmission electron microscopy. 2. ReactionsJohn F. W. Keana, Marc D. Ogan, Yixin. Lu, Michael. Beer, and J. VarkeyCite t…
Abstract New data are reported on the crystallization kinetics of potassium sulfate solutions in a laboratory‐scale continuous MSMPR cooling crystallizer. Population density distributions determined down to 1 μm by laser light scattering and sieve analysis are corrected for the effects of crystal agglomeration and sha…
Six cell-free extracts have been used to characterize the nature of DNA signals and trans-acting factors responsible for the transcription enhancement of the Bombyx mori fibroin gene. The upstream element of the fibroin gene involved in the enhancement can be divided into two regions. The proximal region, -72 to -32,…
The ligand L, which is ideally suited for octahedral coordination, forces this coordination geometry upon Pd11 in the diamagnetic complexes 1 (green) and 2 (blue) and also serves in 3 (orange-brown) as a tridentate ligand. In all three cases, however, the axial PdS bonds are significantly longer than the equatorial.
Six species of ruminal bacteria were surveyed for the phosphoenolpyruvate (PEP)-dependent phosphorylation of glucose. Selenomonas ruminantium HD4, Streptococcus bovis JB1, and Megasphaera elsdenii B159 all showed significant activity, but Butyrivibrio fibrisolvens 49, Bacteroides succinogenes S85, and Bacteroides rumi…
Abstract Geometrical probability can be used as a basis for the quantification of XPS‐signals stemming from random samples such as, for instance, supported heterogeneous catalysts. From a study of three ideal cases, namely extended layers of constant thickness, equally sized spheres and hemispheres on a randomly orien…
Static minimization techniques have been used to study diffusion processes down coincident tilt boundaries in NiO. The activation energies calculated for cation vacancy hopping down grain boundaries were found to be significantly lower than the corresponding energy in bulk NiO. Indeed the ratios for the total activati…
We study the growth of dendritic crystals from a supersaturated solution in a channel geometry. This model provides a continuous interpolation between the Saffman-Taylor problem and the (two-dimensional) free-space dendrite. We derive an integral equation for the shape of steady-state propagating fingers, which we tre…
Magnetochemical studies performed on 3d transition metal fluorides and cyanides are reported. The antiferromagnetic and ferrimagnetic behavior observed for various members of the two series of compounds is shown to depend on the geometric and electronic features of the crystal structures and ions. Variation of these f…
Type IV collagen incubated at elevated temperatures in physiologic buffers self-associates (a) via its carboxy-terminal (NC1) domain, (b) via its amino-terminal (7S) domain, and (c) laterally; and it forms a network. When examined with the technique of rotary shadowing, isolated domain NC1 was found to bind along the…
The sequence specificities of a series of cationic metalloporphyrins toward a 139 base pair restriction fragment of pBR-322 DNA have been studied by DNase I footprinting methodology. Analysis using controlled digests and quantitative autoradiography/microdensitometry revealed that the 5- and 6-coordinate complexes of…
SUMMARY We describe a technique for efficient, quantitative, standardless elemental mapping using a high‐angle annular detector in a scanning transmission electron microscope (STEM) to collect elastically scattered electrons. With a single crystal specimen, contrast due to thickness variations, diffraction, and channe…
Abstract This paper is devoted to the study of the reactions taking place in molten bisphenol‐A polycarbonate‐poly(ethylene terephthalate) mixtures. The analysis of the reaction products by infrared, proton and nuclear magnetic resonance spectroscopy, and by thermogravimetric analysis shows that the main reaction is a…
Article Refinement of the crystal structure of tetraphosphorus decaoxide was published on December 1, 1986 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 177, issue 1-4).
The temperature dependence of the Pt L3-edge EXAFS spectra of the platinum clusters encaged in the cavities of the NaY-zeolite were observed by use of synchrotron radiation. A contraction of Pt-Pt bond by 0.07 Å from the distance in the bulk Pt metal is observed, which is likely to be associated with a strong electron…