Materials Literature
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In recent years a number of imaging techniques to determine the optical properties of materials, either in reflection or in transmission, have been developed. Here the use of an imaging version of the so-called rotating-polarizer method in the study of phase transformations in crystals is demonstrated. This method cre…
A novel synthesis of octafluoro[2.2]paracyclophane (AF4), one that remarkably does not require the use of high dilution methodology, is presented. Using this unprecedented methodology, AF4 is produced in 60% yield in a reaction of Zn with 0.35 M p-bis(chlorodifluoromethyl)benzene in DMA at 100 degrees C. The process c…
Copper is classed as a transition metal both from its physico-chemical properties and its biochemical behavior. This review includes thirty formally copper(III) compounds where crystal structure has been determined. Coordination number four dominates with mostly a square-planar arrangement about the copper(III) atom.…
Within the mode-coupling theory (MCT) for the evolution of structural relaxation in glass-forming liquids, correlation functions and susceptibility spectra are calculated characterizing the rotational dynamics of a top-down symmetric dumbbell molecule, consisting of two fused hard spheres immersed in a hard-sphere sys…
The phase behavior of the supercritical (SC) CO 2 /styrene/poly(vinyl chloride) (PVC) system was studied at 40 °C in the pressure range from 80 to 160 bar. The styrene concentration in the fluid phase ranged from 0 to 0.4 mol/L. The mass uptakes of styrene in PVC films before and after depressurization were obtained.…
The crystal structure of [(C5H4BMe2)2Fe]-4,4′-bipyridine [2 · bipy]n has been determined by the method of simulated annealing from high resolution X-ray powder diffraction at room temperature. The compound is of interest, because it proves that highly ordered organometallic macromolecules can be formed in the solid st…
We investigate long-time translational and rotational self-diffusion of fluorocarbon tracer spheres (100 nm radius) in aqueous dispersions of silica host spheres (10 nm radius). Diffusion is measured as a function of ionic strength (0−10 mM NaCl) and for host-sphere volume fractions up to 37% using depolarized dynamic…
The rate of polypeptide chain elongation is up to one order of magnitude faster in prokaryotic cells than in eukaryotes. Here we report that the rates of in vitro refolding of orthologous prokaryotic and eukaryotic proteins correlate with their differential rates of biosynthesis. The mitochondrial and cytosolic aspart…
We have examined the nanomechanics of a carbon nanotube by a manipulation technique using a scanning electron microscope. Young's modulus of the nanotube, estimated from the buckling under force acting on the axial direction of the nanotube, agrees well with the value estimated from the bending under force acting on t…
The potential of porphyrins and related macrocycles for applications in molecular electronics owes much to the fundamental studies of the photosynthetic light-harvesting arrays and reaction centers. The use of model systems to better understand these essential processes has resulted in the development of an assortment…
Since a few years Mg alloys see a renaissance as light-weight materials for automobiles. In cars the Mg-alloys have to withstand elevated temperatures. Under these conditions the time dependence of the deformation of Mg-alloys must no longer be neglected. Therefore a basic research program was started in cooperation w…
Next generation microelectronic packaging requirements are driving the need to produce increasingly lower dielectric constant materials while maintaining high thermal stability and ease of processing. Efforts have focused on the synthesis and analysis of new polymers with the goals of high thermal stability [degradati…
In 1991 Sumio Iijima used a high-resolunon transmission electron microscope to study the soot created in an electrical discharge between two carbon electrodes at the NEC Fundamental Research Laboratory in Tsukuba, Japan. He found that the soot contained structures that consisted of several concentric tubes of carbon,…
The redox chemistry of Co ions in cavities of zeolite MFI has been studied in materials prepared by solid-state ion exchange and displaying Co/Al ratios varying from 0.4 to 1.0. Fourier Transform Infrared (FTIR) spectroscopy, electron spin resonance (ESR), and diffuse reflectance UV−visible spectroscopy were used to i…
A ferroelectric superlattice consisting of two ferroelectric materials is investigated based on the transverse Ising model. We study the effects of long-range coupling interactions on the spontaneous polarization, the Curie temperature, and the dielectric susceptibility of the ferroelectric superlattice. We find that…
The mesopores in silica fibers run in a circular direction around the axis(see Figure), as demonstrated here by examining the optical properties and electron microscopy images of mesoporous silica fibers grown by slow acid synthesis. These fibers are a unique example of a material that is highly ordered on the nanomet…
We report evidence for two distinct strain-induced orientation transitions in a lyotropic bcc cubic crystal submitted to increasing shear rates. The crystal is built up from copolymer spherical micelles in a selective solvent. The distribution of orientations is characterized by x-ray diffraction: in the two oriented…
Abstract The solid state reaction between sodium tri‐titanate and sodium carbonate, forming mainly sodium pentatitanate, was investigated. Experiments were carried out in a micro‐differential reactor made of quartz glass at various temperatures between 800°C and 880°C and in a pilot fluidized bed reactor operated in a…
Precise X-ray powder diffraction data are given for two germanides, CoGe and Co 5 Ge 7 . The refined unit cell parameters for CoGe are a =11.630(1) Å, b =3.8014(3) Å, c =4.9347(3) Å and β=100.889(8)° (space group C 2/ m , Pearson symbol mC 16) with volume of the unit cell 214.24(2) Å 3 ; the figures of merit are M 20…
Microbiologically‐influenced corrosion (MIC) is a type of corrosion in which, by its nature, many uncertainties exist. Using fuzzy logic, two models of MIC are modified to define a fuzzy set of risk of MIC in conditionally‐protected pipes.