Materials Literature
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Two DTPA derivatives (PIP-DTPA and AZEP-DTPA) as potential contrast enhancement agents in MRI are synthesized. The T1 and T2 relaxivities of their corresponding Gd(III) complexes are reported. At clinically relevant field strengths, the relaxivities of the complexes are comparable to that of the contrast agent, Gd(DTP…
A PPV derivative, poly( 2 -methoxy, 5 -( n -hexadecyloxy)- p -phenylenevinylene) (MH−PPV), has been synthesized by the Gilch route to study the influence of long alkyl side chains on the organization behavior of film at the air−water interface and multilayer structure obtained by Langmuir−Blodgett technique. The π− A…
A new class of Monte Carlo algorithms for atomistic simulation of genuine high polymer systems is proposed. Derivations of two of these algorithms, dubbed “directed internal bridging” (DIB) and “directed end bridging” (DEB), are presented. Their performance is analyzed in detail, using linear united-atom polyethylene…
We have studied by ab initio molecular dynamics the interconversion between oxygen deficient centers (Si---Si bond, dicoordinated silicon =Si:, and ${E}^{\ensuremath{'}}$ centers) induced by UV irradiation in $a\ensuremath{-}{\mathrm{SiO}}_{2}$. By dynamical simulations in the excited state of a periodic model of $a\e…
New octopus polythioether 1 and polysulfoxide 2 incorporating rigid Ph–COOH groups, prepared in high yields by a direct and selective procedure, encapsulate terbium(III) ions affording polymeric complexes with interesting vapor-chromic luminescent properties.
The temperature-frequency behaviour of the complex dielectric permittivity of K 0.957 Li 0.043 TaO 3 (KLT) was studied in detail. Below 250 K a pronounced relaxation-type dielectric dispersion occurs with two wide temperature maxima shifted to lower temperatures increasing in magnitude as the alternating-current monit…
The strain-induced phenomena in cured amorphous EPDM and semicrystalline ethane−octene copolymer ( m -PE) were studied using 1 H T 2 NMR relaxation. Samples studied differed with regard to network structure; i.e., EPDM had a larger density of chemical cross-links, whereas the total network density in m -PE was signifi…
The free-carrier scattering time and plasma frequency in ${\mathrm{PF}}_{6}$ doped polypyrrole near the metal-insulator transition (MIT) is obtained by dielectric spectroscopy (8--700 GHz) down to 2 K. The specific T-dependence allows us to quantify the distance to the MIT for both metallic and insulating samples. The…
Electrical relaxation data of crystalline yttria-stabilized zirconia are used to analyze the permittivity change observed in the spectra of the real part of the permittivity in ionic conducting materials. It is found that this permittivity change is independent of both temperature and mobile-ion concentration, and it…
The spinodal decomposition (SD) of poly(methyl methacrylate)/poly(styrene- co -acrylonitrile) (PMMA/SAN) blends is investigated by the time-resolved small-angle light scattering (SALS) technique. It is found experimentally that the evolution of scattering intensity follows the time−temperature superposition principle.…
High-resolution resonant polarized x-ray diffraction experiments near the sulfur K edge have been performed on free-standing liquid crystal films exhibiting the chiral smectic-C*FI2 phase. It is widely accepted that this phase has a four-layer repeat unit, but the internal structure of the repeat unit remains controve…
Liquid-crystalline complexes of Pd(II) allow a new approach to the realisation of the biaxial nematic phase.
The shape of a crystal is an important characteristic which can influence fundamental properties of the material, including the rate of dissolution, solubility, stability in storage, and compressibility. Understanding the mechanism by which a material with distinct internal structure crystallizes and forms different s…
First-principles calculations on a primary solid solution of ${\mathrm{LaNi}}_{5}\ensuremath{-}\mathrm{H}$ and a hypothetically ordered full hydride, ${\mathrm{LaNi}}_{5}{\mathrm{H}}_{7}$ have been made employing ultrasoft pseudopotentials and plane-wave basis. Some intermediate hydrides were calculated as well. A ful…
The structure of lead-silicate glasses: molecular dynamics and EXAFS studies, Jaroslaw Rybicki, Anna Rybicka, Agnieszka Witkowska, Grzegorz Bergmański, Andrea Di Cicco, Marco Minicucci, Giorgio Mancini
A model is developed that describes temperature and pressure dependence of dielectric relaxation, ionic conductivity, and viscosity of glass-forming liquids near the glass transition temperature. The expressions for ionic conductivity are compared with experimental results for two polymer electrolytes. Those for diele…
The organization of liquid crystalline fluorinated acrylate polymers has been generally described so far in the literature in terms of phase segregation between hydrogenated and fluorinated moieties within the polymer and preferential orientation induced by the backbone. However, little is known on the effects of the…
Crystallization of poly(vinyl alcohol) in the presence of an inorganic filler surface (sodium montmorillonite, MMT) was observed and compared to the crystallization of the neat polymer. For this purpose, several atomic force microscopy modes, providing spatial resolution between amorphous and crystalline polymer, are…
The preparation and characterization of gold nanoparticles (approximately 3 nm in diameter) capped with thiolated alpha- and beta-cyclodextrins (alpha and beta-CD) is described. The CD-capped nanoparticles are hydrophilic and bind ferrocene derivatives as evidenced by electrochemical and (1)H NMR spectroscopic measure…
Core−shell CdS/SiO 2 nanoparticles were prepared and modified with the atom transfer radical polymerization (ATRP) initiator 3-(2-bromopropionyloxy)propyl dimethylethoxysilane (BIDS). The initiator-modified nanoparticles were then used as macroinitiators for the polymerization of methyl methacrylate (MMA) catalyzed by…