Materials Literature
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OBJECTIVE: Poly(lactic acid-co-glycolic acid) (PLAGA) microspheres are promising systems for interstitial chemotherapy of brain tumors. They can be readily implanted by stereotaxy and are biocompatible with the brain, in which they are totally biodegraded within 2 months. 5-Fluorouracil (5-FU) was selected for encapsu…
Large signal-to-background (S/B) ratios for the Fe(CN)(6)(3)(-)(/4)(-) and IrCl(6)(2)(-)(/3)(-) redox couples in KCl have been observed in cyclic voltammetric measurements made at a conductive diamond thin-film electrode without any conventional surface pretreatment. The S/B ratios were a factor of ∼16 and 8 larger at…
The $^{13}\mathrm{C}$ nuclear spin-lattice relaxation rate, $^{13}$${\mathit{T}}_{1}^{\mathrm{\ensuremath{-}}1}$, has been measured in the superconducting state of \ensuremath{\kappa}-(BEDT-TTF${)}_{2}$Cu[N(CN${)}_{2}$]Br in a field parallel to the conducting layers. The $^{13}$${\mathit{T}}_{1}^{\mathrm{\ensuremath{-…
A computer program, called OOPS, is described which facilitates and speeds up the process of rebuilding a protein structure inside its electron density and reduces the chances of local errors persevering throughout the crystallographic protein structure determination process. The program uses a set of criteria to judg…
A genetic and phenotypic analysis of the gene pannier is described. Animals mutant for strong alleles die as embryos in which the cells of the amnioserosa are prematurely lost. This leads to a dorsal cuticular hole. The dorsal-most cells of the imagos are also affected: viable mutants exhibit a cleft along the dorsal…
Abstract Amorphous carbon nitride coatings of thickness of 5 and 30 nm were deposited onto 65 and 95 mm magnetic thin-film rigid disks surfaces using single-cathode and dual-cathode magnetron sputtering systems containing nitrogen-argon plasmas. Under optimum deposition conditions, amorphous carbon nitride coatings ca…
Liquid crystalline compounds containing a difluoromethyleneoxy (CF 2 O) bridge , which increases the polarity, have been synthesized and investigated. The physical properties related to liquid crystal applications (i.e., phase transitions, viscosity, dielectric anisotropy, birefringence) are reported. The compounds sh…
Waveguide grating couplers allow the essential function of waveguide access to be integrated together with optical processing functions on a monolithic planar substrate. Grating coupling technology is topologically and, to a large extent, technologically compatible with the planar processes which define the optical pr…
X-ray diffuse scattering from protein crystals is, at the moment, the only available experimental process to be directly sensitive to long-range correlations between protein-atom displacements. It is shown here that calculations based on independent rigid-body displacements of individual molecules yield a description…
Thermal decomposition of normal transition metal selenite dihydrates, MSeO2.2H2O; M [dbnd] Cu(II), Ni(II), Co(II) was traced by TGA/DTA measurements from 50–700°C. The thermal products were obtained by heating the selenites in an air-oven to different temperatures, as determined from TGA/DTA curves, where different co…
Abstract The results described herein demonstrate the advantages of functionalized initiators with respect to the efficiency of α-chain-end functionalization and the ability to effect post-polymerization functionalization and linking reactions with the living ω-carbanionic chain ends. Not all functionalized initiators…
Transition metal oxides are important materials in heterogenous catalysis, as supporting materials as well as active components. The catalytic activity of Cr2O3 for IE polymerization of olefines or hydrogenation of alkenes is well known and rather high. Therefore, it is important to get information on the surface elec…
The disappearance of the boroxol rings has been identified as the microscopic structural change which occurs in a-${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$ upon pressure induced densification. Although changes in ``ring statistics'' is often assumed to be responsible for densification, our results provide the first unambig…
Abstract A new constitutive model for the nonlinear behavior of noncrosslinked polymers with infinitesimal strains is derived. It generalizes a model of adaptive links for the viscoelastic behavior of crosslinked polymers. According to the model, a viscoelastic medium is treated as a set of elastic springs that replac…
Abstract Grünes Di(phthalocyaninato)lanthanid(III), [M(Pc) 2 ] (M = Lanthanid‐Ion: La‥(‐Ce, Pm)‥Lu) wird durch elektrochemische Oxydation von ( n Bu 4 N)[M(Pc 2− ) 2 ] in CH 2 Cl 2 /( n Bu 4 N)ClO 4 dargestellt. In den UV‐Vis‐NIR‐Spektren treten die für den Pc 2− ‐Liganden typischen π‐π*‐Übergänge bei ca. 15000 cm −1…
The plastic flow behavior of wrought Co-27Cr-5Mo-0.05C alloy was investigated at 298 K as a function of grain size using uniaxial tension testing. The microstructures produced by deformation were characterized using X-ray diffraction, reflected light, and scanning electron microscopy. This study revealed that material…
Experimental data suggest that NOM promotes the formation of pits in a certain narrow range of concentrations and suppresses this type of corrosion at higher dosages. Natural organic matter (NOM) profoundly affected the corrosion of copper in a moderately alkaline synthetic water. It decreased the rate of corrosion, i…
A quick, cheap and simple method of mixing liquid binding agents with rock powder to produce powder pellets suitable for x-ray fluorescence analysis is described. The preparation and use of a polyvinylpyrrolidone–methylcellulose-based liquid binding agent is also described.
Birefringence is caused by orientation of polymer chains during injection molding or extrusion, and is a large obstacle to optical applications. Transparent zero-birefringence copolymers were successfully synthesized by randomly copolymerizing two monomers having positive and negative birefringence, respectively. Sinc…
Open-cell foams have been transformed in prior studies, to a re-entrant (inward bulging) cell structure which gives rise to a negative Poisson's ratio. Different methods were used for polymer foams with and without a softening point. In this study, methods based on air pressure were developed for the transformation of…