Materials Literature
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Porphyrins bearing specific patterns of substituents are crucial building blocks in biomimetic and materials chemistry. We have developed methodology that avoids statistical reactions, employs minimal chromatography, and affords up to gram quantities of regioisomerically pure porphyrins bearing predesignated patterns…
Novel ampholytic grafted polysaccharides were prepared by grafting the Zwitterionic monomer 2-(2-methacryloethyldimeth-ylammonio) ethanoate onto hydroxyethyl cellulose. Ethylenediamine tetraacetic acid was used in combination with ceric ammonium nitrate as the redox initiator. The effects of various factors such as in…
Spin probe rotational mobility has been studied by means of saturation transfer ESR in malto-oligomer−water glasses and has been compared to water mobility as measured by 1 H NMR. Increasing the water content from 10 to 30 wt % leads to a decrease in spin probe mobility at T g while the water mobility increases at T g…
The reactions of various derivatives of chelidamic acid (4-hydroxypyridine-2,6-dicarboxylic acid) with p-tert-butylcalix[4]arene have produced several new mono- and difunctionalized derivatives of the calixarene in which tridentate functional groups suitable for the binding of rare earth metal cations have been incorp…
Photoemission in the system of linear charged chains has been studied with the dipole matrix incorporated, from which its dependencies on the photoelectron momentum (${\bf k}$), photon polarization ($\hat{\bf E}$), and photon energy ($ω$) can be explored. The used model is the three-dimensional array of noninteracting…
Cuttlebone is a highly organized calcium carbonate biomineral with an elaborate macroporous architecture consisting of mineralized sheets and supporting wall structures that are constructed on a β-chitin matrix (figure). Removal of the calcium carbonate by demineralization results in an intact polysaccharide matrix th…
Reversible anion binding in aqueous media at chiral Eu III and Tb III centers has been characterized by 1 H NMR and by changes in the emission intensity and circular polarization following direct or sensitized (365 nm) excitation via an alkylphenanthridinium chromophore. Using a series of heptadentate tri-amide or pol…
In this paper the problem of the Mott metal-insulator transition in vanadium dioxide driven by an external electric field is considered. Delay time ( t d ) measurements have shown that the experimental value of t d is almost three orders of magnitude lower than the theoretical value, calculated in a simple electrother…
We report the observation of memorized polarization-dependent light scattering in a Eu2+-doped fluoroaluminate glass sample. Anisotropic light scattering along the plane of the light polarization was observed in the glass sample after the excitation of a focused 800 nm, 150 fs laser beam at a repetition rate of 200 kH…
The influence of the concentration and size of sp2 carbon clusters on the field emission properties of hydrogenated amorphous carbon thin films is investigated. In combination with electron paramagnetic resonance and optical measurements, it is shown that the trend in the threshold field for emission for films deposit…
Photostructural change of glassy As2Se3 was simulated on an experimentally credible model with excited electronic dynamics within first-principles molecular dynamics. Bond breaking and bond switching reactions account for local changes around defect sites at the short time phase of illumination. For long-time relaxati…
Amorphous and crystalline phases of Ge2Sb2Te5 films are investigated by coherent phonon spectroscopy. By heating amorphous films above specific temperatures, the coherent phonon signatures exhibit pronounced changes due to the crystallization of the amorphous phase into a cubic lattice and the transition from the cubi…
Microcrystalline cellulose (MCC) is a very important product in pharmaceutic, food, cosmetic and other industries. In this work, MCC was prepared from soybean husk, produced in large quantities in soybean oil processing industries. It was characterized through various techniques (scanning electron microscopy (SEM), in…
Highly oriented boron carbonitride (BCN) nanostructures consisting of nanotubes and nanofibers have been synthesized by bias-assisted hot-filament chemical vapor deposition from the source gases of B2H6, CH4, N2, and H2. It is found that the B concentration of the BCN nanostructures increases with increasing B2H6 in t…
The following features of multiwalled BN nanotubes were discovered using a field emission high-resolution analytical transmission electron microscope: (i) coexistence of hexagonal and rhombohedral stacking in nanotube shell assembly; (ii) flattening of nanotube cross section, which makes possible clear atomic resoluti…
Adsorption and desorption of an oxygen molecule on carbon nanotubes are investigated using density functional calculations. Several precursor states exist at the edge of armchair nanotubes, whereas an exothermic adsorption takes place at the edge of zigzag nanotubes. We also estimate desorption barriers of a CO molecu…
Surfaces of reactively evaporated In2O3 films were investigated in situ by synchrotron-excited photoemission. Work function, valence band maximum, and electronic states in the band gap were determined as a function of oxygen pressure. Surface and bulk electronic properties can only be explained consistently with the a…
Two methods are proposed to evaluate the second-order elastic constants of quantum mechanically treated solids. One method is based on path-integral simulations in the (NVT) ensemble using an estimator for elastic constants. The other method is based on simulations in the (NpT) ensemble exploiting the relationship bet…
We propose a junction of metal and rare-earth compound semiconductor as the basis for a possible efficient low-temperature thermoelectric device. If an overlayer of rare earth atoms differing from the bulk is placed at the interface, very high values of the figure of merit ZT can be reached at low temperature. This is…
The exciton decay rate at a rough interface in type-II semiconductor superlattices is investigated. It is shown that the possibility of recombination of indirect excitons at a plane interface essentially affects kinetics of the exciton photoluminescence at a rough interface. This happens because of strong correlation…