Materials Literature
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This work presents an application of recently developed ideas about how to map real polymer systems onto abstract models. In our case the abstract model is the bond fluctuation model with a Monte Carlo dynamics. We study the temperature dependence of chain dimensions and of the self-diffusion behavior in the melt from…
Crystal structure of zinnwaldite 2M(1) was refined in the Cc space group with R equal to 5.8% and R(w) 7.5%. Its octahedral sheet is hetero-octahedral, with octahedra around M1 and M3 having the same mean cation-anion bond length, whereas the third (around M2) has the mean bond significantly shorter. In terms of elect…
The Rouse–Zimm discrete hydrodynamic model is extended to acyclic macromolecules of any topology, and particular attention is devoted to starlike dendrimers and other symmetric cascade structures. As a first approximation, freely rotating models are built for branched structures by means of appropriate choices of topo…
We have mapped out the complete phase diagram of hard spherocylinders as a function of the shape anisotropy L/D. Special computational techniques were required to locate phase transitions in the limit L/D→∞ and in the close-packing limit for L/D→0. The phase boundaries of five different phases were established: the is…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
Charge distributions in maleic anhydride (MAH) grafted polyethylene (g-PE)/ethylene - vinyl - acetate (EVA) copolymer laminates have been measured with materials of different composition. All laminates showed interfacial charge, the polarity and the magnitude of which are explained by interfacial polarization. It was…
Clusters with and without cavities are formed in the reaction of [CdCl2(PPh3)2] with PhSeSiMe3. Depending on the organic solvent used, [Cd10Se4(SePh)12(PPh3)4] or [Cd16(SePh)32(PPh3)2] (depicted on the right; the cluster is almost completely covered with phenyl rings) crystallizes. The clusters are composed of fused a…
A markedly different emission behavior is exhibited by the two rhenium complexes 1 and 2. These can be interconverted photochemically; the forward reaction (cyclization to the “closed” form) is triggered by visible light, and the reverse reaction by UV light. Therefore, this is a photoswitchable molecular system in wh…
D3d symmetry characterizes complex 1 (see structure on the right). This circular molecular contains 18 high-spin, antiferromagnetically coupled iron(III) centers. Isolated as the double salt 1 · 6Et4N(NO3) · 15CH3OH · 6Et2O · 24H2O it is the largest cyclic ferric cluster yet reported.
For the development of molecule‐based switching devices , cobalt and manganese complexes of 1,2‐benzoquinone ligands are of great interest. These compounds have electronically labile ground states, which leads to phenomena such as mixed valency, spin crossover, and valence tautomerism. Recently, the electronic behavio…
A 16-amino acid oligopeptide forms a stable beta-sheet structure in water. In physiological solutions it is able to self-assemble to form a macroscopic matrix that stains with Congo red. On raising the temperature of the aqueous solution above 70 degrees C, an abrupt structural transition occurs in the CD spectra from…
Applying a practical density-functional-based perturbation theory, we examine the phase behaviour of a model system interacting via a hard core plus a square-shoulder repulsion. For sufficiently narrow shoulders, the theory predicts coexistence between expanded and condensed isostructural (fcc) crystals, in quantitati…
Studies were performed to develop a sub-100 nm biodegradable colloidal system for the efficient delivery of drugs and diagnostic agents to the lymphatic system. Nanospheres of poly(lactide-co-glycolide) were prepared by interfacial polymer deposition. The nanospheres were coated with block co-polymers in order to modi…
We demonstrate improvement in fatigue resistance and other ferroelectric properties through cerium doping in sol–gel derived lead zirconate titanate thin films. We have studied frequency dependence of fatigue behavior and show that the loss of polarization due to fatigue follows a universal scaling behavior with N/f2,…
The excitation spectra of photo- and thermo-luminescence were compared in the VUV - UV spectral region in and scheelite tungstates. Temperature dependences of emission intensities and decay times were measured for in the 80 - 300 K range and approximated by a simple phenomenological model. The energy level structure o…
Optical nonlinearity of liquid crystals (LC) in the isotropic phase can be enhanced by 1 order of magnitude by dissolving 0.1% of anthraquinone dye in the LC. The enhancement decreases by $\ensuremath{\sim}30%$ when the LC transforms into the nematic phase. The same guest-host effect also exists in non-LC liquids. It…
The microscopic dynamics of several phases of solid ethanol are studied under the same thermodynamic conditions by inelastic neutron scattering. It is found that the vibrational density of states of the orientational glass phase, where the molecules are arranged on an ordered lattice but with disordered orientations,…
Total energies, electronic structure, surface energies, polarization, potentials and charge densities were studied for slabs of BaTiO_3 using the Linearized Augmented Plane Wave (LAPW) method. The depolarization field inhibits ferroelectricity in the slabs, and the macroscopic field set up across a ferroelectric slab…
In this article, we have reviewed the recent progress of the experimental studies on ultra-thin films of graphite and hexagonal boron nitride (h-BN) by using angle-resolved electron spectroscopy together with other techniques. The fundamental properties of these high-quality films are discussed on the basis of the dat…
In this work, we performed infrared spectroscopic studies of the reaction of poly(acrylic acid) (PAA) and metal oxides (ZnO, CaO, CuO, Cr2O3, and Al2O3). Factors such as the amount of metal oxide, reaction time, solvents, the kind of metal oxides, and temperature were also evaluated to derive the optimum condition for…