Materials Literature
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An approach that couples compartmental modeling with high resolution methods is developed to simulate spatial variations in the crystal size and shape distribution in solution crystallization processes. This is the first time that compartmental modeling has been applied to a crystal system with multiple characteristic…
A significant proportion of materials are produced in crystalline form. Many of these crystals are produced by nucleation and growth from solution. In these processes, the control of the crystal size distribution can be critically important for efficient downstream operations such as filtration and drying, and product…
Interstellar dust contains a component that reveals its presence by emitting a broad unstructured band of light in the 540-950 nm wavelength range, referred to as extended red emission (ERE). The presence of interstellar dust and ultraviolet photons are two necessary conditions for ERE to occur. This is the basis for…
Advances in sensor technology and increased competition in the pharmaceutical industry have generated significant interest in the identification of models for the solution formation of crystals with multiple characteristic dimensions. A procedure is proposed that uses a small number of batch experiments to identify th…
Several dihydrogen complexes of ruthenium of the form [Cp/Cp*Ru(P-P)H(2)](+) (P-P = chelating diphosphine ligand) have been prepared by reaction of the corresponding neutral chloride complexes with H(2) in the presence of NaB(ArF)(4). Treatment with D(2) or T(2) gas leads to incorporation of deuterium or tritium in th…
The new compound (C3N2H5)8[MoV5MoVI7O22(BO4)2(PO4)5(HPO4)3].nH2O is the first molybdenum borophosphate. It contains clusters of twelve molybdenum, eight phosphorus and two boron atoms, [Mo12O22(BO4)2(PO4)5(HPO4)3]8- similar to the Wells-Dawson clusters. Five molybdenum atoms are MoV while the others are MoVI, and the…
Recent experiments by Hodak et al. [ J. Phys. Chem. B 2000, 104, 5053] on core−shell nanoparticles have demonstrated that the frequency of the breathing mode is strongly dependent on the shell thickness. Here we compare these measurements with a theoretical model based on classical continuum mechanics, which in itself…
The systematic study of band-filling control for four kinds of organic conductors with various kinds of ground states has succeeded. (1) By partial substitution of (GaCl(4))(-) by (MCl(4))(2-) [M = Co, Zn] in the anion blocking layer of lambda-ET(2)(GaCl(4))(-) [ET = bis(ethylenedithio)tetrathiafulvalene], single crys…
A photochromic dithienylethene, bearing a phenyl azacrown as an ionophore and a formyl group as an electron-accepting substituent, changes its binding ability for Ca2+ by a factor higher than 103 by photoirradiation. This new photoionochromic displays a wavelength-dependent competition between fluorescence and photocy…
Highly stable, isolated, and monodisperse Ag nanoparticles, protected by poly(amidoamine) (PAMAM) dendrimers, were prepared via direct chemical reduction. UV−visible absorption, dynamic light scattering, and transmission electron microscopy have been used to study the structure and behavior of the nanocomposites as a…
The propionyl-CoA synthetase (PrpE) enzyme of Salmonella enterica catalyzes the first step of propionate catabolism, i.e., the activation of propionate to propionyl-CoA. The PrpE enzyme was purified, and its kinetic properties were determined. Evidence is presented that the conversion of propionate to propionyl-CoA pr…
We have prepared a green chromophore, 1,7-bis(pyrrolidin-1-yl)-3,4:9,10-perylene-bis(dicarboximide) (5PDI), that exhibits photophysical and redox properties similar to those of chlorophyll a (Chl a ), yet unlike Chl a, it can be easily functionalized and incorporated into a wide variety of biomimetic electron donor−ac…
We find that photoexcited electrons in an n-GaAs epilayer rapidly (< 50 ps) spin-polarize due to the proximity of an epitaxial ferromagnetic metal. Comparison between MnAs/GaAs and Fe/GaAs structures reveals that this coherent spin polarization is aligned antiparallel and parallel to their magnetizations, respectively…
We report the formation of open nanoporous polymer films composed of homogeneous polysulfone/polyimide blends. Porosity is introduced by expansion of carbon dioxide-saturated films at elevated temperatures. To interpret details of the porous morphologies in terms of the experimental conditions during expansion, the gl…
We report the first computer experiments with supercooled polymer melts of chains long enough to form chain-folded structures. These structures resemble the lamellae of polymer crystals, and the inverse of the lamellar thickness is related linearly to the crystallization temperature as found in experiments. The small-…
Silicalite nanoparticles and starch gel templates have been used to fabricate zeolite materials with a hierarchical micro/meso/macropore organization. Two methods were investigated. First, macroporous monoliths consisting of a continuous mesoporous framework of microporous silicalite were prepared by incorporating 50-…
ZnS and ZnSe precursors (ZnS x 0.5en and ZnSe x 0.5en, en = ethylenediamine) were prepared via a solvothermal process using ethylenediamine as solvent. Phase-pure hexagonal wurtzite ZnS and ZnSe products were obtained by annealing the precursors in argon stream at temperatures above 350 degrees C. The role of ethylene…
Metal, metal oxide, and plastic surfaces were modified with poly(vinylpyridine) using adsorption, spin-coating, and dip-coating techniques and various metal, semiconductor, and dielectric nanoparticles were subsequently attached. Prior to the modification, the substrates were treated with glow discharge plasma for cle…
124 Silberatome und 57 Selenidliganden enthält der Clusterkomplex [Ag124Se57(SePtBu2)4Cl6(tBu2P(CH2)3PtBu2)12]. Er hat Abmessungen von etwa 3 nm. Das Selenteilgerüst (siehe Bild) zeigt einen schalenartigen Aufbau mit einem Frank-Kasper-Polyeder (rot) im Zentrum. Außer der Struktur dieses Komplexes werden auch die von…
The dependence of the flow-induced isotropic-to-nematic (I−N) phase transition phenomenon on the spacer length is investigated using the well-behaved thermotropic polymers, PSHQ n, with n representing the number of methylene groups as flexible spacer in the main chain. Using optical microrheology methods and mechanica…