Materials Literature
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The synthesis, electrochemical properties, and molecular structure of a new pi-electron donor, 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP), is described. In contrast to the hitherto-known tetrachalcogenafulvalene pi-donors providing organic superconductors, this donor contains only the bis-fuse…
1,3,5-Trinitro-2,4,6-tris(styryl)benzene derivatives 1−3 were synthesized and their optical properties, first hyperpolarizabilities (β), powder SHG efficiencies, and Td, were determined. They exhibited significant β [β(0) = (24−89) × 10-30 esu] and powder SHG values [M/MmNA = 0.2−5.8] as well as high thermal stabiliti…
The oxidized disulfide form of the ubiquitous tripeptide glutathione (gamma-glu-cys-gly) (GSSG) is shown to produce transparent, thermoreversible gels in aqueous solutions of dimethyl sulfoxide, dimethylformamide, and methanol, at GSSG concentrations as low as 1.5 mM. The gels bind Congo Red and exhibit dramatic green…
Single-molecule spectroscopy was used to follow the orientation of a single probe molecule in a polymer film in real time. Broad spatially heterogeneous dynamics were observed on long time scales, which result from simple diffusive rotational motions on short time scales. This diffusive behavior persists for many rota…
Observation of the constant loss contribution to the light scattering spectra in GHz frequency range is presented. The constant loss appears as a frequency-independent imaginary part of the susceptibility spectrum. It shows a strong temperature variation. Analysis of the spectra and literature data suggests that the c…
We have explored the possibility of double-exchange interaction between ions of different elements by studying a series of ${\mathrm{LaMn}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{O}}_{3}$ $(0.1<~x<~0.7)$ perovskites, with the measurements of magnetization, resistivity, magnetoresistance, infrared spectra, a…
Steam-exploded fibers from flax (Linum usitatissimum) are heterogeneously acetylated using acetic anhydride and sulfuric acid as catalyst, with the aim to modify the surface properties without changing fiber structure and morphology. The acetylation reaction follows first-order kinetics up to a reaction time that depe…
In this study, phase transformation of the hexagonal mesostructure MCM-41 to the cubic mesostructure MCM-48 is examined by in situ X-ray diffraction (XRD) of the transforming mesostructure and by XRD of products from bulk transformation experiments in Parr autoclaves. Transformations were studied under conditions of h…
Synthesis in 1% oxygen at 930C leads to non-superconducting RuSr2GdCu2O8 in which superconductivity subsequently can be induced with oxygen annealings without observable stoichiometric changes. Detailed ac susceptibility and zero-field muon spin rotation experiments reveal that the superconducting compounds always exh…
We present a theory of a single point, line or plane defect coupling to the square of the order parameter in a metallic system near a quantum critical point at or above its upper critical dimension. At criticality, a spin droplet is nucleated around the defect with droplet core size determined by the strength of the d…
We study how the ferroelastic domain structure sets in in an epitaxial film of a material with second order proper ferroelastic transition. The domain structures considered are similar to either $a_{1}/a_{2}/a_{1}/a_{2}$ or $c/a/c/a$ structures in perovskite ferroelectrics. If the "extrinsic" misfit strain, not associ…
In order to understand the unexpected superconducting behavior of MgB$_2$ compound we have made electronic structure calculations for MgB$_2$ and closely related systems. Our calculated Debye temperature from the elastic properties indicate that the average phonon frequency is very large in MgB$_2$ compared with other…
We review the search for the glass transition in water in its various amorphous forms, and highlight the paradoxes that the search has produced. Focussing on the glassy form of water obtained by hyperquenching, we examine its reported calorimetric properties in the light of new findings for bulk glassformers vitrified…
The determination of the structure of transient molecules, such as photoexcited states, in disordered media (such as in solution) usually requires methods with high temporal resolution. The transient molecular structure of a reaction intermediate produced by photoexcitation of NiTPP-L2 (NiTPP, nickeltetraphenylporphyr…
A series of photophysical measurements and semiempirical calculations were carried out with 1,4-bis(phenylethynyl)benzene in search of evidence on the effects of phenyl group rotation and chromophore aggregation of oligo- and poly(phenyleneethynylene)s. It is suggested that planarization gives rise to relatively modes…
PMMA-layered silicate nanocomposites were prepared by in-situ suspension polymerization and emulsion polymerization. For the suspension polymerization, the silicate layers were dispersed individually in water, and we speculate that they are adsorbed on the surface of monomer droplets. For the emulsion polymerization,…
Crystallization of concentrated colloidal suspensions was studied in real space with laser scanning confocal microscopy. Direct imaging in three dimensions allowed identification and observation of both nucleation and growth of crystalline regions, providing an experimental measure of properties of the nucleating crys…
A well cleaned copper plate with a thin Au layer deposited was heated in air to make hole transfer sites with p-Cu 2 O at 800 °C for 3 min. A transparent NiO layer was prepared on the surface of this device to make electron transfer sites on the surface. This heat-treated device, having 2 µm Au layers, exhibited a rem…
Metalation of C6H6 has been known for a long time as a side reaction occurring in refluxing benzene solutions of Rh2(CO)4(TPP) (TTP = tetraphenylporphyrin). Rather than representing the intrinsic reactivity of this complex, such hydrocarbon activation proceeds via RhII(por) and RhIII(por) derivatives resulting from ox…
The widths of the peaks in the pair distribution function (PDF) contain information on the phonons of a material. At large interatomic distances r the width of the peaks is fully determined by the thermal parameters. For low r, however, correlation effects reduce the width significantly, depending on the shape of the…