Materials Literature
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Polyimides with a combination of properties including low solar absorptivity (α) in thin films, atomic oxygen (AO), and ultraviolet (UV) radiation resistance, solubility in organic solvents in the imide form, high glass transition ( T g ) temperatures, and high thermal stability have been prepared and characterized. T…
Selective, sensitive cation capture: A bichromophoric “H”-foldamer (rigid-flexible-rigid) demonstrates a cation-steered exciton interaction (see figure; the interaction is denoted by the double-headed arrow) and thereby allows the selective signaling of Ca2+-ion binding among Na+, K+, and Mg2+ ions. The binding can be…
The effect of nanoscopic particles on the mesophase structure of diblock copolymers was discussed. The parameters of phase diagram were calculated using the segregation scaling theory (SST) as a function of the particle interaction parameters for the entire range of the diblock compositions. The results showed that th…
A major challenge for the study of the magnetically shape-controlled memory alloys Ni-Mn-Ga is the structural search for their variants. We report studies of the variants of Ni 2 MnGa alloys from a theoretical point of view by means of density functional calculations using the generalized gradient approximation. The e…
Discotic liquid crystals have emerged as very attractive organic semiconductors due to their high degree of ordering and self-healing capacity. Quantum-chemical calculations that describe the main parameters governing the charge-transfer processes in these systems at the molecular level are reported. The concepts are…
The optical and redox properties of a series of 3,4-ethylenedioxythiophene oligomers (EDOTn, n=1-4) and their beta,beta'-unsubstituted analogues (Tn, n=1-4) are described. Both series are end capped with phenyl groups to prevent irreversible alpha-coupling reactions during oxidative doping. Absorption and fluorescence…
A crosslinked cholesteric network doped with a fluorescent dye exhibits lasing efficiencies that are more than one order of magnitude higher than those of a low molar mass cholesteric liquid crystal (CLC) with similar optical parameters. The emission from the samples has been found to be stable, whereby the lasing thr…
We propose a model Hamiltonian for describing charge transport through short homogeneous double stranded DNA molecules. We show that the hybridization of the overlapping pi orbitals in the base-pair stack coupled to the backbone is sufficient to predict the existence of a gap in the nonequilibrium current-voltage char…
We have examined a method of direct extraction of accurate tight-binding parameters from an ab-initio band-structure calculation. The linear muffin-tin potential method, in its full-potential implementation, has been used to provide the hamiltonian and overlap matrix elements in the momentum space. These matrix elemen…
The effect of random surface roughness on hydrodynamics of viscous incompressible liquid is discussed. Roughness-driven contributions to hydrodynamic flows, energy dissipation, and friction force are calculated in a wide range of parameters. When the hydrodynamic decay length (the viscous wave penetration depth) is la…
A synthesis of beta-Co(OH)2 nanocrystalline materials has been investigated with the assistance of chelating agent ethylenediamine. By controlling precipitation processes, various forms of beta-Co(OH)2 crystallites can be prepared at different stages. The crystallite morphologies include two-dimensional hexagonal shee…
The influence of contacts on linear transport through a molecular wire attached to mesoscopic tubule leads is studied. It is shown that low dimensional leads, such as carbon nanotubes, in contrast to bulky electrodes, strongly affect transport properties. By focusing on the specificity of the lead-wire contact, we sho…
Four series of tensile loading-unloading tests are performed on isotactic polypropylene in the sub-yield domain of deformations at room temperature. In the first series, injection-molded specimens are used as produced, whereas in the other series the samples are annealed for 24 h at 120, 140 and 160 C, which covers th…
A model is derived for the viscoelastic response of glasses at isothermal uniaxial deformation with small strains. A glass is treated as an ensemble of relaxing units with various activation energies for rearrangement. With reference to the energy-landscape concept, the rearrangement process is thought of as a series…
Transition metal oxides are widely used as both catalysts and catalytic supports in industrial processes. However, the mechanisms by which these materials function as catalysts and the structure−reactivity relationships are not well understood . In particular, there is a paucity of information on the specific sites re…
Angle-resolved photoemission is employed to measure the band structure of TiSe2 in order to clarify the nature of the ( 2 x 2 x 2) charge density wave transition. The results show a very small indirect gap in the normal phase transforming into a larger indirect gap at a different location in the Brillouin zone. Fermi…
Helices on helices: Nanohelices of polycrystalline cadmium sulfide (see transmission electron micrograph) have been made by the mineralization of helical self-assembled objects shaped like twisted ribbons. The coiled morphology of the inorganic helices apparently results from growth on only one face of the organic rib…
The engineering of tissue for mechanically demanding applications in the cardiovascular system is likely to require mechanical conditioning of cell-scaffold constructs prior to their implantation. Scaffold properties amenable to such an application include high elasticity and strength coupled with controllable biodegr…
Neutron diffraction with isotope substitution is used to determine the structures of high (HDA) and low (LDA) density amorphous ice. Both "phases" are fully hydrogen bonded, tetrahedral networks, with local order similarities between LDA and ice Ih, and HDA and liquid water. Moving from HDA, through liquid water and L…
This paper describes the functionalization of the surfaces of gold nanoshells, which consist of silica nanoparticles coated with a continuous thin layer of gold. Previous studies have shown that gold nanoshells exhibit optical properties similar to those of metal colloids (e.g., strong optical absorptions and large th…