Materials Literature
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Fullerene soot with a high content of single-wall carbon nanotubes was tested to assess its potential biochemical activity. The results of dermatological trials did not show any signs of health hazard related to skin irritation and allergic risks.
To determine whether carbon nanotubes can induce any significant health hazards we applied methods routinely used in the pathophysiological testing of asbestos-induced disease to show that the soot with a high content of CNTs does not induce any abnormalities of pulmonary function or measurable inflammation in guinea…
Frequency dispersion associated with dielectric relaxation phenomena in polycrystalline cubic pyrochlore with normal composition (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 is analyzed. Measurements at cryogenic temperatures and high frequencies reveal a broad distribution of relaxation times. The associated dielectric loss data can b…
When a suspension consisting of dielectric particles having nonlinear characteristics is subjected to a sinusoidal (ac) field, the electrical response will in general consist of ac fields at frequencies of the higher-order harmonics. These ac responses will also be anisotropic. In this work, a self-consistent formalis…
We report the synthesis of cyclophanes 18-20 by ester-forming macrocyclization reactions of diols 15 and 16 with 1,4-benzenedicarbonyl chloride. Compounds 18 and 19 display a two-electron, quasireversible oxidation wave in the cyclic voltammogram to yield the dication species at E(ox)(pa) 0.52 and 0.47 V, respectively…
Structure and surface polarity properties of poly(vinylformamide- co -vinylamine) (PVFA- co -PVAm)/silica hybrid materials are investigated by means of electrokinetic measurements, atomic force microscopy (AFM), and solvatochromic probes. AFM measurements show the complete covering of the silica surface with the PVFA-…
Glutamate synthase is a complex iron-sulfur flavoprotein that catalyzes the reductive transfer of the L-glutamine amide group to C(2) of 2-oxoglutarate, forming two molecules of L-glutamate. The bacterial enzyme is an alphabeta protomer, which contains one FAD (on the beta subunit, approximately 50 kDa), one FMN (on t…
A novel laser photolysis source has been used to synthesize hydrogen-terminated silicon clusters Si n H x +, where n ≤ 50. Using mass spectrometry, the hydrogen content of the Si n H x + clusters with n = 10−30 was measured as a function of temperature from 300 to 950 K. For n = 10−22 at the lower temperatures, there…
Chemical modification of the argon plasma-pretreated Si(100) surface by UV-induced surface graft polymerization with either glycidyl methacrylate (GMA) or glycidyl acrylate (GA) was carried out. The GA graft polymerized Si substrate was further subjected to coupling reaction with aniline (An) and finally oxidative gra…
The study of catalytic behavior begins with one seemingly simple process, namely the hydrogenation of O to H2O on platinum. Despite the apparent simplicity its mechanism has been much debated. We have used density functional theory with gradient corrections to examine microscopic reaction pathways for several elementa…
Single crystals of Ti 2+ doped NaCl were grown by the Bridgeman technique. High resolution variable temperature absorption, continuous-wave emission, and time-dependent measurements were performed for the spectroscopic characterization of the title compound. At T < 100 K excitation of Ti 2+:NaCl in the red spectral re…
The alkali metal/group 4 metal/polychalcogenides Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) have been synthesized by means of the reactive flux method at 823 or 873 K. Cs(4)Ti(3)Se(13) crystallizes in a new structure type in space group…
The nanostructure deformation mechanism of a predrawn and annealed blend of poly(ethylene terephthalate) (PET) and polyethylene (PE) (PET/PE: 50/50 by wt %) was studied. For the first time six-point small-angle X-ray scattering (SAXS) patterns were observed as a function of elongation in the investigation of a drawn p…
A strategy was developed to create a modulable polymer surface architecture (topography, chemical composition) at the nanometer scale. Therefore, collagen was first adsorbed on a poly(methyl methacrylate) (PMMA) substrate and dried at high or low rate to produce continuous or discontinuous layers, respectively. Soluti…
Chromium-promoted ceria catalyst materials have been prepared by three routes: impregnation of ceria gel using an aqueous solution of CrO 3 (Cr(VI)/CeO 2 -imp), impregnation of ceria gel using an aqueous solution of chromium(III) nitrate (Cr(III)/CeO 2 -imp), and coprecipitation from an aqueous solution containing bot…
Abstract Polymer blend technology has been one of the most investigated areas in polymer science in the past 3 decades. The one area of polymer blends that has been virtually ignored involves simple emulsion blends, although several articles have recently appeared that address film formation and mechanical characteris…
Novel fluorinated main-chain liquid crystalline/crystalline polymers were prepared through thin film polymerization. Two polymer systems were studied: one from 2,6-acetoxynaphthoic acid (ANA), acetoxyacetanilide (AAA), and 4,4‘-(hexafluoroisopropylidene)bis(benzoic acid) (6F acid) and the other from ANA, hydroquinone…
Treatment of vessel surfaces is common practice in many protein crystallization protocols. The research reported here shows that such treatments can have a significant effect on the resulting kinetics of protein crystallization. Untreated and silanized low-protein-binding polystyrene wells were used in batch isotherma…
[reaction: see text] All of the crystalline o-anisaldehyde derivatives 1 and 3 change to brick-red color upon brief exposure to UV-vis radiation. The red color, attributed to (E)-xylylenol, is remarkably persistent for hours (ca. 10 h) in the case of 1c; such a long lifetime for the reactive o-xylylenols is unpreceden…
Results presented give evidence of the existence of quasicritical, fluidlike behavior in the isotropic phase of 4-cyano-4-pentyl-biphenyl (5CB) for frequencies ranging from the static to the ionic-dominated [low-frequency (LF)] region. Despite the boost of dielectric permittivity on lowering the frequency below 1 kHz,…