Materials Literature
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Scientists have sought for over two decades to incorporate the necessary attributes of transparency, stability, and high nonlinear susceptibilities into optimized organic or organometallic chromophores for third-order nonlinear optical (NLO) applications. These investigations have provided an ever-expanding understand…
The streamer-to-spark transition is an important sub-process of the flashover of high-voltage apparatus. In this paper an investigation of this transition in an electrode gap of the order of 1 cm in dry air with a non-uniform field distribution is presented. Parameters such as the gap distance, polarity of applied vol…
We present results of a computer simulation of protein crystal growth based on the Monte Carlo random process and surface kinetics of a growing crystal, which includes site-dependent detachment and migration, and site-independent attachment processes. The results indicate that, if only monomers are included in the att…
We studied physiological conditions during the spinning of dragline silk by the garden cross spider, Araneus diadematus. Silk is converted from the liquid feedstock in the gland into a solid thread via a tapering tubular duct and exits at a spigot. The distal part of the tubule appears specialized for ion transport an…
The band structure theory of magnetism in 3d-4f compounds is reviewed. Among the open-shell electrons, a hierarchy of interactions is present which governs the intrinsic magnetic properties of these materials. Density functional theory (DFT) is an appropriate tool to describe and quantitatively investigate both ground…
The structural features of the interface between the cystalline and amorphous phases of Si solid are studied in simulations based on a combination of empirical interatomic potentials and a nonorthogonal tight-binding model. The tight-binding Hamiltonian was created and tested for the types of structures and distortion…
We have measured the magnetic susceptibilities of single crystals of Cu_{1-x}Zn_xGeO_3 with extremely low Zn concentration (x) lower than x=5x10^{-3} at very low temperatures to investigate the spin-Peierls and antiferromagnetic transitions. The results show that the undoped CuGeO_3 has no antiferromagnetic phase down…
The goal of this work was to design a ferromagnetically coupled Mn(2+)Ni(2+) species. For this, we attempted to combine nitro-nitrito and end-on azido bridges which are both known to be ferromagnetic couplers. This has led us to the compound of formula Mn(N(3))(4)[Ni(en)(2)NO(2)](2) (en = ethylenediamine). The crystal…
The synthesis and characterization of two chiral, redox-active Rh(I) bis(diphenylphosphinite) monomers, complexes 3 and 4, are reported. Complex 4, [(η 2 -1,2- bis(diphenylphosphinite),4-oxo-6-(3‘-α-terthiophene)Rh(I)(η 4 -C 7 H 8 )]BF 4, can be electrochemically polymerized to form poly- 4, and the η 4 -C 7 H 8 ligan…
The reaction between 2 molar equiv of 3-butyrolactone (BL) and either methylalumoxane (MAO) or isobutylalumoxane (IBAO) yielded an adduct, either MAO−BL or IBAO−BL. Both MAO−BL and IBAO−BL were found to be much more effective catalysts for the ring-opening polymerization of the racemic monomer, [ R, S ]-BL, than eithe…
We study the behavior of a semi-infinite monolayer, which is placed initially on a half of an infinite in both directions, ideal crystalline surface, and then evolves in time due to random motion of the monolayer particles. Particles dynamics is modeled as the Kawasaki particle-vacancy exchange process in the presence…
We present Molecular Dynamics (MD), Quasi Harmonic Lattice Dynamics (QHLD) and Energy Minimization (EM) calculations for the crystal structure of Ne, Ar, Kr and Xe as a function of pressure and temperature. New Lennard-Jones (LJ) parameters are obtained for Ne, Kr and Xe to reproduce the experimental pressure dependen…
Abstract Fiberglass piping has typically been prohibited from use in dry deluge fire protection systems and in confined spaces for reasons of flammability, smoke density and toxicity. Advanced resin technology has emerged which breaks through these barriers. The .light weight, corrosion resistance and low maintenance…
The -type cubic compound, , undergoes below a spontaneous magnetic transition at . The magnetic phase diagrams have been determined from the magnetization curves measured on a single crystal in fields up to 10 T. The corresponding magnetic structures have been determined from neutron diffraction studies on the same cr…
Als ferromagnetisch gekoppeltes Spinpentamer wurde das makrocyclische Polyradikal 1 konzipiert. Für diesen Kohlenwasserstoff ergaben Magnetisierungsmessungen einen durchschnittlichen Spin von S = 10 im Grundzustand, was der bislang größten für ein organisches Molekül gemessenen Spinquantenzahl entspricht. Ar = tBuC6H4.
The title compound is not a hexaboride, as was believed for many years. It is therefore not surprising that its structure also contains a novelty: for the first time a pentagonal B7 bipyramid (shown on the right) has been identified as part of the framework of boron atoms in a solid-state compound.
The temperature dependence of the Debye-Waller factors of a 9.4 mol% stabilized cubic ceramic was studied in the range 4-1923 K using neutron powder diffraction. It was found that the data could not be modelled on a harmonic Debye-like model with an additive static disorder component but are significantly anharmonic.…
The porphyrin–surfactant interaction determines the activity of the title catalysts. Amphiphilic porphyrin derivatives (e.g. 1 with M=MnCl, R=CH2CH2(OCH2CH2)2OH) are easy to prepare and can be included in micellar phases.
We study statistical properties of energy spectra of two-dimensional quasiperiodic tight-binding models. Taking into account the symmetries of models defined on various finite approximants of quasiperiodic tilings, we find that the underlying universal level-spacing distribution is given by the Gaussian orthogonal ran…
Resistivity (15 - 710 K), magnetization (80 - 723 K), and calorimetric (200 - 623 K) measurements on have shown evidence for the formation of Jahn - Teller (JT) polarons below . Above 560 K, activated conduction with is observed and shows Curie - Weiss behaviour. Over the temperature range 270 - 340 K, the conductivit…