Materials Literature
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[reaction: see text] All of the crystalline o-anisaldehyde derivatives 1 and 3 change to brick-red color upon brief exposure to UV-vis radiation. The red color, attributed to (E)-xylylenol, is remarkably persistent for hours (ca. 10 h) in the case of 1c; such a long lifetime for the reactive o-xylylenols is unpreceden…
Results presented give evidence of the existence of quasicritical, fluidlike behavior in the isotropic phase of 4-cyano-4-pentyl-biphenyl (5CB) for frequencies ranging from the static to the ionic-dominated [low-frequency (LF)] region. Despite the boost of dielectric permittivity on lowering the frequency below 1 kHz,…
An $s\ensuremath{-}\mathrm{p}\mathrm{o}\mathrm{l}\mathrm{a}\mathrm{r}\mathrm{i}\mathrm{z}\mathrm{e}\mathrm{d}$ laser beam that impinges at small incidence angle on a homeotropically aligned nematic liquid crystal produces very interesting nonlinear phenomena. In this paper, we show that, due to the symmetry of the sys…
We investigate the effect of phase inversion on the domain morphology and rheological properties of phase-separated polybutadiene/polyisoprene blends using optical microscopy, light scattering, and rheometry. Two different blends, low-vinyl polybutadiene/low-vinyl polyisoprene (LPB/LPI) and low-vinyl polybutadiene/hig…
The level of conjugation of diethylenetriaminepentaacetic acid (DTPA) to the polysaccharide sodium hyaluronan (HA) has been measured by a colorimetric assay, isothermal titration calorimetry (ITC), and (1)H NMR spectroscopy. The colorimetric assay is based on the red shift, upon complexation with gadolinium ion (Gd3+)…
The isothermal crystallization of poly(ethylene oxide) (PEO), single-C 60 -end-capped PEO (FPEO), and double-C 60 -end-capped PEO (FPEOF) has been evaluated using polarized optical microscopy (POM) and differential scanning calorimetry (DSC). Comparison studies were also made on a physical mixture of PEO and C 60 with…
Theoretical and experimental studies in the literature on the coupling between functionalized polymer chains at immiscible polymer−polymer interfaces have always involved second-order kinetics. In addition, the time dependence of the degree of copolymer formation has been predicted to vary depending on the reaction st…
Abstract Several kinds of organic–inorganic hybrids were synthesized from an epoxy resin and a silane alkoxide with a primary amine‐type curing agent or tertiary amine curing catalyst. In the hybrid systems cured with the primary amine‐type curing agent, the storage modulus in the high‐temperature region increased, an…
High-order harmonic generation by metallic carbon nanotubes exposed to an intense ultrashort pulse has been theoretically investigated in the semiclassical approximation. The mechanism of nonlinearity provided by the motion of \ensuremath{\pi} electrons has been considered. It has been shown that the high density of c…
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…