Materials Literature
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Understanding the detailed electronic structure of deep defect states in narrow band-gap semiconductors has been a challenging problem. Recently, self-consistent ab initio calculations within density functional theory using supercell models have been successful in tackling this problem. In this paper, we carry out suc…
We study the quasiparticle band structure of isolated, infinite HF and HCl bent (zigzag) chains and examine the effect of the crystal field on the energy levels of the constituent monomers. The chains are one of the simplest but realistic models of the corresponding three-dimensional crystalline solids. To describe th…
Transport of cholesterol into the mitochondria is the rate-determining, hormone-sensitive step in steroid biosynthesis. Here we report that the mechanism underlying mitochondrial cholesterol transport involves the formation of a macromolecular signaling complex composed of the outer mitochondrial membrane translocator…
Aiming at the high-contrast photochromic switching of fluorescence emission and its perfect nondestructive readout, a polymer film highly loaded with a specific photochromic compound, 1,2-bis(2'-methyl-5'-phenyl-3'-thienyl)perfluorocyclopentene (BP-BTE), and an excited-state intramolecular proton-transfer (ESIPT)-acti…
Porous, fibrous carbon nanofibers containing hollow cores (see image) are fabricated by electrospinning two immiscible polymer solutions followed by thermal treatment at 1000 °C in an inert atmosphere. This new type of carbon nanofibers has controlled porosity combined with a low density and expected high electrical a…
Back to the grind: Three-component solids are prepared by neat and liquid-assisted grinding. Various solid or liquid guests are incorporated into a caffeine/succinic acid host framework. These grinding methods are superior to solution crystallization for the screening of ternary inclusion compounds.
This paper reports a simple, inexpensive, and high-yield synthetic route to Sr 2 Si 5 N 8:Eu 2+ -based red nitridosilicate phosphors for white light-emitting diodes (LEDs). Through the chemical reaction of SrCO 3, Eu 2 O 3, and Si 3 N 4 rather than the air-sensitive Sr, Eu, Si(NH) 2, Sr 3 N 2, and EuN powders, a compl…
A new furnace, based on a halogen lamp, and a sample cell have been designed and constructed for in situ X-ray absorption spectroscopy experiments in conventional and dispersive mode (transmission and fluorescence geometries). The main application of the apparatus is thermal treatment studies under controlled conditio…
Zn(II) and Cu(II) porphyrins with beta-conjugated barbiturate functional groups have low-energy electronic transitions which are unusual in that there are two strong bands in the Soret region. Resonance excitation of the two bands shows that each has features characteristic of both the porphyrin and barbiturate groups…
Carbon monoxide molecules generated in the channels of mesoporous MCM-41 silica sieve from a precursor (diphenyl cyclopropenone) by photodissociation with a nanosecond laser pulse were monitored by time-resolved Fourier transform infrared (FTIR) spectroscopy using the step-scan and rapid-scan methods. A very broad abs…
Solvent inclusion in organic crystals is quite uncommon, as it is observed in only 15% of cases. Solvation could be imagined to result from the interruption of the “normal” crystallization process because of the preferential formation of directional hydrogen bonds between the included solvent and the organic component…
A rigorous integral equation formulation in conjunction with Green's function theory is used to analyze the waveguiding and coupling phenomena in nonsymmetric (composed of dissimilar slabs) optical couplers with gratings etched on both slabs. The resulting integral equation is solved by applying an entire-domain Galer…
In this study, we demonstrate that single crystalline tellurium with a 2D, scroll-like structure that deviates from the intrinsic linear crystallographic nature can be controllably synthesized via a modified polyol process by the reduction of tellurium nitrate (Te−N−O) in refluxing ethylene glycol, where no growth mod…
The incidence of thrombogenesis and occlusion of cardiovascular implants is likely to be reduced by endothelial cell (EC) growth promotion on biomaterials used for device fabrication. However, proper signaling between the matrix proteins deposited on the device surface and the cells grown on it is a prime requirement…
This manuscript chronicles the evolution of software used originally to control a diffractometer at a macromolecular crystallography beamline. The system has been augmented and rewritten. A modular and carefully organized suite of programs now handles the whole experimental environment from a single vantage point. It…
Rauf und runter: Die molekularen M10-Räder [M10(OMe)20(O2CR)10] (M=Ga, R=Me; M=Fe, R=Ph) konnten in einer templatfreien Synthese durch Einfügen eines Diolatliganden in M18-Räder überführt werden (siehe Kalottenmodell von [Ga18(pd)12(pdH)12(O2CMe)6(NO3)6]6+; Ga gelb, O rot, N blau, C grau; pdH2=1,3-Propandiol). Erstaun…
The transmittance of thin films of Sc deposited by evaporation in ultrahigh vacuum conditions has been investigated in the 20-1000 eV spectral range. Transmittance measurements were performed in situ on Sc layers that were deposited over grids coated with a C support film. Transmittance measurements were used to obtai…
In this work we present a simple method for the characterization of a ferroelectric liquid crystal (FLC) optical modulator and the optimization of its contrast ratio. This device acts as switchable wave-plate, where the orientations of the principal axes rotate under the action of a bipolar applied voltage. It is desi…
The Drude tail due to photo-excited carriers in single-walled carbon nanotubes (SWNTs) has been observed in the mid-infrared region by using combination spectroscopy of synchrotron radiation and Ti:sapphire laser. It is found that the density of photo-excited carriers increases as the sample temperature is raised from…
The Cellular Potts Model (CPM) successfully simulates drainage and shear in foams. Here we use the CPM to investigate instabilities due to the flow of a single large bubble in a dry, monodisperse two-dimensional flowing foam. As in experiments in a Hele-Shaw cell, above a threshold velocity the large bubble moves fast…