Materials Literature
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We report on large scale numerical simulations of fracture surfaces using random fuse networks for two very different disorders. There are some properties and exponents that are different for the two distributions, but others, notably the roughness exponents, seem universal. For the universal roughness exponent we fou…
We perform molecular dynamics simulations of friction for atomically thin Xe films sliding on Ag(111). We determine the inverse of the coefficient of friction (i.e. slip time) by direct calculation of the decay of the center of mass velocity after applying an external force, as well as from the velocity autocorrelatio…
X-ray measurements show that GeO2 and Ge nanocrystals with a radius from 25 down to 1.5 nm are formed in an oxide matrix after annealing. Under ultraviolet excitation, both types of films luminesce around 3.1 eV, with identical photoluminescence (PL) line shapes and subnanosecond PL dynamics. The strongest PL intensit…
We present an exact formulation of the physics of Barnett relaxation. Our formulation is based on a realistic kinetic model of the relaxation mechanism, which includes the alignment of the grain angular momentum in body coordinates by Barnett dissipation, disalignment by thermal fluctuations, and coupling of the angul…
In this study the microphase separation and structural organization of the hard segment domains were studied as a function of diethanolamine (DEOA) content for two series of model foams based on toluene diisocyanate (TDI) and glycerol initiated ethylene-oxide-capped propylene-oxide or glycerol initiated propylene-oxid…
Gelatin was graft copolymerized with poly(hydroxyethyl methacrylate and butyl acrylate) and subsequently crosslinked with glutaraldehyde. Fibrin of bovine origin was incorporated onto this graft copolymer and characterized for the percentage of grafting. The infrared spectroscopy, mechanical strength, and water absorp…
A novel method is used to study topological and molecular structure of different kinds of sulfur (mineral and two polymeric types). It is based on thermomechanical analysis of solid (not dissolved) polymer. It was found that a deep difference in their molecular weight distributions and in their crystallinity degrees e…
Two- and three-layer composite latex particles were used to prepare rubber-toughened poly(methyl methacrylate) (RT-PMMA). The interfacial thicknesses of the multi-layered particles were varied by using different emulsion polymerization synthesis techniques. The resulting interphases were previously characterized by 13…
The effect of process parameters on the conversion, P, and current efficiency, η, for the aqueous electropolymerization of pyrrole on low-carbon steel has been investigated. The amount of polypyrrole coatings formed on steel, Wp, increased with the charge passed, Q, and the initial pyrrole concentration [M], but was u…
The efficiency of conventional Hindered Amine Stabilizers (HAS) can be significantly reduced by their adsorption on other additives or fillers present in the polymer. The present article reports on the effect of titanium dioxide, phtalocyanine blue, and talc on the thermal and the photo stabilizations of isotactic pol…
Thin polypyrrole coatings (∼ 10 μm thick) were formed on low carbon steel by an aqueous constant current electrochemical polymerization using oxalic acid as the electrolyte. The amount of polypyrrole coatings formed on steel increased with the applied current and monomer concentration. No significant change in the ele…
40000 und 4 nm betragen die relative Molekülmasse bzw. der Durchmesser von [As 12 Ce 16 ‐(H 2 O) 36 W 148 O 524 ] 76− , das damit gemeinsam mit seinem La III ‐Analogon die bislang größten wasserlöslichen anorganischen Cluster bildet. Die Polyoxoanionen mit ihren 164 Metallatomen sind auf einfache Weise in guten Ausbeu…
A structural phase transformation in the CuO_2 planes of YBa_2Cu_3O_x has been observed at the onset of the overdoped regime, x=6.95. We have measured as a function of x the dimpling in the CuO_2 planes by EXAFS, and the O2,3 in-phase (A_1g) mode by Raman scattering. The data show for x>6.95 anomalously large static d…
Conductance fluctuations have been observed in macroscopic, quasi 3D PbTe wide quantum wells. A significant increase of the correlation field occurs in a temperature range from 40 mK to 1.2K. At the same time the fluctuation amplitude stays near e^2/h although the lateral sample size is two orders of magnitude larger…
In PbTe wide parabolic quantum wells (WPQW) a plateau-like structure is observed in the Hall resistance, which corresponds to the Shubnikov-de Haas oscillations in the same manner as known from the quantum Hall effect. At the same time a non-local signal is observed which corresponds to the structure in Rxx and Rxy. W…
Combined X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) experiments have been carried out on GaAsO4 (berlinite structure) at high pressure and room temperature. XAS measurements indicate four-fold to six-fold coordination changes for both cations. The two local coordination transformations occur at di…
We investigate the high magnetic field regime of wide quantum wells (WQW) for the case of a many valley host semiconductor. The complete system is described within a modified Landauer-Buettiker formalism and we demonstrate that a parallel contribution of two electron systems in different valleys of the band structure…
We present magneto transport experiments of quasi 3D PbTe wide quantum wells. A plateau-like structure in the Hall resistance is observed, which corresponds to the Shubnikov de Haas oscillations in the same manner as known from the quantum Hall effect. The onsets of plateaux in Rxy do not correspond to 2D filling fact…
The results of non-local experiments in different contact configurations are discussed in terms of a non-local behaviour of the contact arms. It is shown that the observed reproducible fluctuations can be understood to result from fluctuations of a non-local bulk current in the contact arms. The fluctuations are expla…
EXAFS spectroscopy experiments have been carried out on quartz-like GaAsO4 and AlAsO4 at high pressure and room temperature. It has been shown that these materials exhibit two structural phase transitions; the first transition to a high pressure crystalline form occurs at 9 GPa and is reversible upon decompression, wh…