Materials Literature
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The embedding of a quantum mechanical region in a molecular mechanical environment allows a theoretical treatment of very large systems. This article reviews recent methodological developments for such hybrid methods and surveys selected applications including solvation effects, enzymatic reactions, and electronic exc…
Magnetic Barkhausen emission (MBE) has been used to characterize various microstructures in tempered 0.2 wt% C steel, 2.25Cr—1Mo steel and 9Cr—1Mo steel samples (where the composition is in approximate weight per cent). A two-stage process of irreversible magnetic domain wall movement during magnetization is proposed…
Through numerical experiments we investigate stress localization in granular material with application to plastic-bonded explosives. The results shed light on static versus dynamic loading, and on the role of an interstitial material between grains. Under static loading, we observe stress localization and bridging in…
Investigations of the effects of polymerization conditions on the molecular weight distribution (MWD) of polyethylene synthesized with soluble metallocene/methylaluminoxane (MAO) catalysts have been performed. The following variables were investigated in this study: catalyst type, polymerization temperature, catalyst…
A basic aluminium chloride with high chlorine content (basicity 1.85) has been crystallized from a concentrated aqueous solution. Its crystal structure has been determined by X-ray structure analysis. The structure contains tridecameric cations of a novel type consisting only of interconnected AlO6 octahedra. The form…
The new mineral tschortnerite, ideally Ca 4 (K,Ca,Sr,Ba) 3 Cu 3 (0H) 8 [Si 12 Al 12 0 4S ]·ϰH 2 0, ϰ > 20, occurs as well-formed cubes up to a maximum size of 0.15 mm in a Ca-rich xenolith at the Bellberg volcano near Mayen, Eifel, Germany. The light blue, transparent crystals are optically isotropic, n = 1.504(2).…
The dynamic response of various materials exposed to liquid jet and pressure wave impacts was simulated making use of an elastoplastic solid model. Numerical pit profiles were compared to experimental ones produced in test materials by the cavitation of water, mercury, or sodium. It was found that a high pressure wave…
Effective medium theory is useful for designing optical elements with a form-birefringent subwavelength structure. We describe a way to determine the effective refractive indices and the directions of their principal axes for two-dimensional (2-D) subwavelength gratings in the normal incidence case. The effective indi…
High-resolution optical interferometry was used to investigate the effects of forced solution convection on the crystal growth kinetics of the model protein lysozyme. Most experiments were conducted with 99.99% pure protein solutions. To study impurity effects, ∼1% of lysozyme dimer (covalently bound) was added in som…
Abstract The micro-inclusions located in the genetic centre of Yakutian diamond monocrystals have been studied using optical (anomalous birefringence, photoluminescence, cathodoluminescence) and microanalytical (electron-microprobe, proton-microprobe, scanning electron microscope) methods. Most diamonds nucleated hete…
The interaction of fast charged particles with a semi-infinite medium is described using both quantum-mechanical and semiclassical dielectric formulations. We consider the coupling with bulk and surface excitations for arbitrary trajectories of the particle and apply the solutions to several cases of special interest.…
In paper I [Wu et al. (1998). J. Appl. Cryst. 31, 356–362] an approach was developed to the problem of modelling dislocation-induced X-ray or neutron-diffraction-line broadening. This paper applies those findings to the Rietveld refinement of the neutron powder diffraction profiles of deuterium-cycled LaNi5 and β-PdD0…
We investigated the structural changes of carbon in diamond films deposited by microwave plasma-assisted chemical vapor deposition with various methane concentrations and substrate temperatures. They were studied by x-ray-absorption near-edge structure (XANES) at the C $K$ edge. The results on composition and structur…
Abstract The thermal stability of bentonites is of particular interest for containment barriers in nuclear waste storage facilities. The kinetics of smectite reactions have been investigated under laboratory conditions for some time. The variables of time, chemical composition and temperature have been varied in these…
The magnetic properties and the microstructure of Nd–Fe–B and Nd–Fe–Co–Ga–B die upset magnets produced from amorphous materials were studied. The Nd–Fe–B die upset magnets had fine polygonal Nd2Fe14B grains and showed magnetic anisotropy. The compositional modification and optimization of the die upset condition led t…
We have investigated the influence of the coarsening process on the complex shear modulus of three-dimensional aqueous foam. It is shown that the viscoelastic response is governed by a large spectrum of relaxation times and that the complex shear moduli measured as a function of frequency, at different foam ages, can…
A method for using in situ X‐ray absorption near edge spectroscopy to determine the composition of passive, transpassive, and nonreducible thin oxide films is described. The method is demonstrated by determining the composition of the passive films formed in pH 4.5, 0.1 M acetate buffer, on 100 Å thick Fe‐ y /Cr alloy…
This letter reports on the influence of a static electric field applied by metal electrodes on the agglomeration process of carbon black (CB) in epoxy resin. The growth of dendrites from the anode into the material is observed in situ by optical transmission microscopy. A percolating network is seen to form, combined…
The microstructure of transition aluminas obtained via the dehydration of boehmite has been characterized by using transmission electron microscopy (TEM). The presence of γ‐, δ‐, and θ‐aluminas was identified by using selected‐area electron diffraction. Modifications that resulted from the reordering of aluminum vacan…
Elastic constants for 12 mol% Ce‐doped tetragonal zirconia have been determined from peak shifts in neutron diffraction patterns recorded under applied uniaxial stress. When these diffraction data are combined with a measured value of Young's modulus, a complete set of elastic constants is obtained. The values are c 1…