Materials Literature
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Two novel diazamesocyclic ligands based on l,5-diazacyclooctane (DACO) and functionalized with additional pyridyl donor groups, namely 1,5-bis(2-pyridylmethyl)-1,5-diazacyclooctane (L1) and 1-(2-pyridylmethyl)-1,5-diazacyclooctane (L2), have been synthesized and characterized, as have their CuII complexes. Crystal str…
The electronic structures of several magnetic semiconductors were calculated using first-principles based electronic structure techniques. Calculations were performed both for periodic supercells and for disordered systems which were treated within the coherent potential approximation. Our results differ from the conv…
Silicate layers cross-linked by interlayer VO5 square pyramids form the basis of the three-dimensional frameworks of the structures of the title compounds (the structure of K2(VO)(Si4O10)⋅H2O is depicted). Alkali metal cations (•) and water molecules (○) occupy nonframework sites in these structures, which were synthe…
We study the hydrogenic impurity in a quantum dot (QD). We employ the effective mass theory with realistic barrier and variable effective mass. The model is simple, but it predicts features not previously observed. We observe that the shallow hydrogenic impurity becomes deeper as the dot size (R) is reduced and with f…
Novel synthesis methods have been investigated for the preparation of Bi 4 Ti 3 O 12 ferroelectric Aurivillius-type powders, namely, the wet no-coprecipitated chemistry using a n -butylamine aqueous solution and two mechanochemical activation techniques (vibrating and planetarium mills). For the sake of comparison, Bi…
Arylamine N-acetyltransferases (EC 2.3.1.5) (NATs) catalyse the biotransformation of many primary arylamines, hydrazines and their N-hydroxylated metabolites, thereby playing an important role in both the detoxification and metabolic activation of numerous xenobiotics. The recently published crystal structure of the S…
A supramolecular recognition interface is formed through the self-assembly of cyclic D,L-peptides. Phenyl–phenyl interactions direct the solid-state organization of dimeric peptide cyclo[(-L-Phe-D-MeN-Ala-L-hPhe-D-MeN-Ala)2] (1) by forming clusters of edge-to-face contacts between dimers (shown left), which suggests t…
The current status and prospects of research on ferromagnetism in tetrahedrally coordinated magnetic semiconductors and their nanostructures are reviewed. Results of a quantitative comparison between experimental and theoretical results, notably for Mn-based III–V and II–VI thin films and heterostructures, are present…
The dispersion of clay−diarylethene hybrid materials into an ionic biopolymer, gelatin, was investigated for the successful preparation of highly functional photochromic films. A mixture of the gelatin and the clay−diarylethene hybrid material dispersed in aqueous N,N -dimethylformamide (DMF) was cast on a glass plate…
The time-resolved electric-field relaxation in glassy D-sorbitol is measured by dielectric hole-burning, i.e. with and without a preceding high electric sinusoidal burn field. The question is whether the burn-induced modifications of the response are frequency-selective (dielectric “holes”) and thus indicative of hete…
We performed annealing experiments on monolamellar polyethyleneoxid crystals. Even well below the melting point, local relaxations of metastable folded states led to pronounced liquidlike morphological changes on a micron scale of shape and perimeter of the crystalline domains, similar to dewetting of liquids. First,…
In this paper we describe the isolation of a second gene in the newly identified pyridoxine biosynthesis pathway of archaebacteria, some eubacteria, fungi, and plants. Although pyridoxine biosynthesis has been thoroughly examined in Escherichia coli, recent characterization of the Cercospora nicotianae biosynthesis ge…
Summary The pH buffering and aluminium solubility characteristics of acid soil are important in determining the soil's response to changes in precipitation acidity. The chemistry of soil organic matter (humic substances) plays a key role in both processes, yet is complex and still poorly understood. Nevertheless, mode…
The enhancement of the near-IR emission intensity at 200 K excited at the F(Br - ) band in oxygen-doped BaFBr was observed. It was found from the corresponding absorption spectra that the origin is attributed to a thermal dissociation between F(Br - ) centers and O - ions. The role of the oxygen-defect centers was inv…
Polycondensation of dimethyl 2,6-anthracenedicarboxylate and aliphatic diols provides poly(alkylene 2,6-anthracenedicarboxylate)s, PxA. The ethylene homologue, P2A, an analog of PET and PEN (two commodity polyesters), is infusible and insoluble. Polymers prepared from other short diols (1,4-butanediol, 1,6-hexanediol)…
On pyrrole! The pyrrole-based corrole ligands can offer an alternative to porphyrin systems. The manganese corroles 1–4 are readily synthesized, undergo metal- not ligand-based redox chemistry, and 4 in particular shows impressive catalytic activity in the oxygenation of styrene with iodosylbenzene.
Passy, S. I. Department of Biology, Rensselaer Polytechnic Institute c/o US Geological Survey, 425 Jordan Rd., Troy, NY 12180‐8349 USA On August 27, 1999, diatoms were sampled and current velocity and depth were measured on a regular square sampling grid at 81 locations in an unshaded, cobble‐bottom reach of White Cre…
Abstract Structure development in the softening/melting processing regime is investigated using the model miscible blend poly(styrene‐co‐acrylonitrile) (SAN)/poly(methyl methacrylate) (PMMA). Feed materials of four different particle sizes are compounded to study their effects upon structure development. Fourier‐trans…
We present what we believe is a new hybrid objective consisting of a gradient-index optical element that has external flat refracting surfaces and is made of two different inhomogeneous materials separated by a cemented spherical surface. Microstructures of diffractive lenses are placed on the flat external surfaces o…
The cathodic polarization of Ni in hydrochloric acid solutions has been investigated using the galvanostatic technique. The rate of hydrogen evolution reaction was found to depend on the concentration and pH of the solution. The reaction order with respect to hydrogen ion was found to be one. The rise of temperature e…