Materials Literature
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A plastic columnar discotic phase is reported for several triphenylene derivatives. It is characterized by a three-dimensional positional order of the molecules, as in a crystalline state, while maintaining the rotational mobility of the molecules. Only very minute changes in structure and dynamics occur at the phase…
Electron irradiation damage of highly graphitized carbon fibre was examined by means of transmission electron microscopy in a multibeam lattice imaging mode together with selected-area electron diffraction. It was found that the (00.2) lattice spacing was homogeneously increased up to about 11% over the whole irradiat…
Modelle zum Umsatz der organischen Bodensubstanz (OBS) werden seit langer Zeit entwickelt. Die Ergebnisse aus Dauerversuchen zeigen, daß mindestens zwei OBS Fraktionen (inert und umsetzbar) existieren. Weitergehende Untersuchungen führten zur Definition einer aktiven und einer stabilisierten Fraktion innerhalb der ums…
The Monte Carlo simulation technique has been used to study the anomalous conductivity of aliovalently doped fluorite-related oxides. In order to investigate the effect of the interaction between the dopants and the oxygen vacancies on the transport behavior, three simple model interactions have been tested: Nearest-n…
Aniline oligomers have been intensively studied in the past years. In particular, aniline oligomers substituted with electron-donor groups have been synthesized and its electronic properties calculated. However, when an electron-acceptor group is attached to the benzenoid ring of the oligoaniline, strong effects over…
The smectic-A phase of octylcyanobiphenyl (8CB) doped with a photosensitive azo-compound has been reported to exhibit structural changes and formation of periodic layers distortions upon exposure to low-level radiation. It is caused by changes in the smectic layer spacing triggered by light-induced molecular photoisom…
Single crystal preparations of the Pb[(Sc 1/2 Nb 1/2 ) 1- X Ti X ]O 3 binary system have been investigated by a flux method using 75 mol%PbO-25 mol%B 2 O 3 flux. The crystals were grown in a platinum crucible by mass crystallization, achieved by slow-cooling the solution at 1° C/h from 1,200° C to 880° C. The resultin…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation A. Romo-Uribe, T. J. Lemmon, A. H. Windle; Structure and linear viscoelastic behavior of main-cha…
The effects of long-range dynamical correlation in the kinetics of order-disorder transitions of symmetric block copolymer melts are investigated on the basis of the time-dependent Ginzburg-Landau model that was extended in such a way that the information on the chain conformation is incorporated using the path-integr…
Hall-effect and space-charge-limited-current (SCLC) measurements were performed on Cl-doped GaSe single crystals grown by the Bridgmann–Stockbarger method. The temperature dependence of the free electron density shows the characteristics of a partially compensated n-type semiconductor. The electrical properties are do…
We propose here a new mechanism of droplet coarsening in phase-separating fluid mixtures. In contrast to the conventional understanding that there are no interactions between droplets in the late stage of spinodal decomposition, we demonstrate the existence of interactions between droplets that is caused by the coupli…
In an attempt to unravel the role of conserved histidine residues in the structure-function of sheep liver cytosolic serine hydroxymethyltransferase (SHMT), three site-specific mutants (H134N, H147N, and H150N) were constructed and expressed. H134N and H147N SHMTs had Km values for L-serine, L-allo-threonine and beta-…
Abstract— We present results from an ongoing study of the infrared (IR) and optical properties of nanodiamonds, an objective of which is to identify spectral features in the laboratory that could also be used telescopically to trace the presence of these particles in the interstellar medium (ISM). Fourier transform mi…
The Young modulus for crystalline polyethylene is calculated using ab initio molecular dynamics based on density functional theory in the local density approximation (DFT-LDA). This modulus, which can be seen as the ultimate value for the Young modulus of polyethylene fibers, is found to be 334 GPa. For the first time…
Porphyrins and metalloporphyrins can be readily functionalized at the meso-(5,10,15,20)-positions by using a variety of reagents, the Vilsmeier formylation reaction being universally regarded as the prototypical example. On the other hand, the literature shows that corroles and metallocorroles are unusually resistant…
The electrochemical etching of n-type GaAs in HF solutions in the dark results in the formation of a porous layer. The pore density, the pore dimensions and the structure of the porous layer depend on the doping density and the crystallographic orientation of the surface. The pore morphology of porous GaAs is essentia…
The effects of complexed metal ions on trans − cis photoisomerization reactions of two azobenzene compounds having a crown ether ring, 1a (small ring) and 1b (large ring) were investigated. The photoisomerization of 2,2‘-dimethoxyazobenzene ( 2 ) was compared as a control. Anomalous increase in the quantum yields of t…
The microscopic dynamics of several monomeric and polymeric glass-forming materials has been investigated by time-resolved fluorescence measurements of doped malachite green molecules in a wide temperature region. For monomers, 1-propanol, propylene glycol, and glycerol, and a polymer without side chains, poly- butadi…
Variation with time of the chemically active three‐phase boundary, due to the spontaneous sintering of metal particles, is simulated with the help of a correlated percolation model. Different modes of variation are obtained depending on the relative composition and porosity and the conditions of sintering. They range…
The longitudinal electromechanical coupling factor ( k 33 ) was investigated as a function of PbNi 1/3 Nb 2/3 O 3 – PbTiO 3 –PbZrO 3 (PNN-PT-PZ) piezoelectric ceramic compositions close to the morphotropic phase boundary (MPB). The k 33 was influenced by the grain size of PNN-PT-PZ ceramics. The composition of the MPB…