Materials Literature
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In this preliminary report we present the mesomorphic properties and electro-optic investigations of three new 'banana-shaped' mesogens. The materials are structurally similar to Niori's the original bent-core materials but possess alkylthio substituents in place of alkoxy substituents. Microscopic investigations reve…
A novel bent-rod hexacatenar liquid crystal is reported that displays a hexagonal columnar (Col h ) phase. The organization of conjugated hexacatenar mesogens in the columnar phase is of interest for their anisotropic electronic properties. The emissive nature of the mesogens varies over the temperature range of the C…
An investigation of the morphological behavior of a series of graft copolymers having multiple regularly spaced, tetrafunctional branch points has been carried out. The behavior of these materials, comprised of polyisoprene backbones with two polystyrene arms grafted to the backbone at each branch point, is shown to b…
A stepwise temperature- and pressure-scanning thermal analysis method was developed to measure glass-transition temperature Tg in the two-phase polymer–gas systems as a function of gas pressure p, and was used to confirm recent theoretical predictions that certain polymer–gas systems exhibit retrograde vitrification,…
In our search for a more versatile protecting group that would exhibit fast release rates for peptides, we have designed and developed the p -hydroxyphenacyl (pHP) group as a new photoremovable protecting group. We report the application of this protecting group for the dipeptide Ala-Ala ( 1 ) and for the nonapeptide…
The influence of manganese on the crystallographic phase and the microstructure of BaTi 1− x Mn x O 3 ceramics (0 ≤ x ≤ 0.05) is investigated. The crystal structure at room temperature changes from tetragonal to hexagonal between x = 0.005 and 0.017, which causes a drastic change in the microstructure. The Jahn_Teller…
The rheological behavior of intercalated polystyrene/layered silicate nanocomposites was investigated. Both storage and loss moduli increased with silicate loading at all frequencies and showed non-terminal behavior at low frequencies which is a typical behavior of non-homogeneous systems with ordered microstructures.…
The progress in the synthesis of organolanthanide complexes supports the exploration of these compounds as initiators for ring-opening polymerization (ROP) of lactones. The performance of these initiators in terms of yield, molecular weight, polydispersity, stereoregularity is affected by the ligands and by the oxidat…
A general and efficient procedure is presented, which allows us to reduce the computational efforts for the calculation of the energy levels of high-nuclearity spin clusters. The method consists of block factorizing the Hamiltonian matrix using the invariance of the spin Hamiltonian with regard to interchanges of spin…
A lower critical solution temperature (LCST) phase transition is reported for blends of the biodegradable polymers poly(D,L-lactide) (PDLA) and poly(ε-caprolactone) (PCL). From light scattering measurements the cloud point curve is determined to have a critical temperature of 86°C and a critical concentration of mass…
Two Pseudomonas aeruginosa genes, termed phaJ1(Pa) and phaJ2(Pa), homologous to the Aeromonas caviae (R)-specific enoyl-CoA hydratase gene (phaJ(Ac)) were cloned using a PCR technique to investigate the monomer-supplying ability for polyhydroxyalkanoate (PHA) synthesis from beta-oxidation cycle. Two expression plasmid…
Nickel nanowire arrays with diameters in the range 30--500 nm have been fabricated by electrochemical deposition into nanoporous, single-crystal mica templates, which allow measurements of the magnetic properties of nickel nanowire arrays at high temperatures. The Curie temperature is found to be reduced by as much as…
A novel simulation model for crystallization of polymer mono-layers is presented and compared with experiments on short PEO chains. We assume that crystallized chains can exist in states of different degrees of order. The resulting morphologies are nonequilibrium intermediate structures which can further relax on incr…
The identity of diamond inclusions in quartz-muscovite gneisses occurring in the Saxonian Erzgebirge near the Saidenbach reservoir was proven by laser-Raman micro-spectroscopy. The identification was additionally backed-up by graphitization of diamond inclusions as a result of irradiation with a high-energy laser beam…
The composition in the surface region of the Heusler alloy NiMnSb has been studied using angle-resolved X-ray photoemission spectroscopy, low-energy electron diffraction and spin-polarized inverse photoemission. The results are consistent with a generally Mn-Sb terminal layer, though the surface composition is very se…
The defect structure of non-stoichiometric strontium titanate thin films epitaxially grown on SrTiO3(100) substrates by pulsed-laser deposition was studied using transmission electron microscopy and X-ray diffraction. The A-site-excess SrTiO3 thin film adopted a completely unrelaxed pseudomorphic perovskite structure…
The electrical properties of grain boundaries in polycrystalline materials can vary from boundary to boundary and conventional impedance measurements yield only averaged information. Local measurements at individual grain boundaries using microelectrodes can partly overcome this restriction. Finite element calculation…
Solid solutions of nonstoichiometric mixed cobalt–zinc ferrite nanoparticles Co0.73yZn0.73(1−y)Fe2.18□0.09O4, were prepared in order to study their magnetic properties as a function of cobalt content y. The saturation magnetization changes with increasing y due to the various occupancies of cations in tetrahedral and…
The interactions of a series of water-soluble dendritic phthalocyanines containing terminal carboxylate functionality with a range of surfactants in aqueous media have been investigated. Cationic surfactants, as compared with neutral and anionic counterparts, are much more effective to disrupt the molecular aggregatio…
An attempt is made to analyze the most important physical properties of manganites of the La-Ca-Mn-O type, which exhibit the colossal magnetoresistance effect. The primary focus is on the peculiarities of these compounds which are reflected in their crystalline, electronic, and magnetic structures and which determine…