Materials Literature
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A series of polyesters were synthesized by the bulk polycondensations of the respective combinations of two difuranic diesters, i.e., bis(5-(methoxycarbonyl)-2-furyl)methane (4a) and 1,1-bis(5-(methoxycarbonyl)-2-furyl)ethane (4b), with two 1,4 : 3,6-dianhydrohexitols [1,4 : 3,6-dianhydro-D-glucitol (1) and 1,4 : 3,6-…
The results of the studies of the structure and properties of non-crystalline (liquid and amorphous) oxide systems obtained using computer simulation methods are summarised. The models of simple oxides, homologous series of non-crystalline oxides and of binary and multi-component oxide systems are considered. The resu…
In nature, supercooled liquids play an important role in areas as diverse as volcanoes and hibernating animals. From a technological standpoint, supercooled liquids are linked intimately to processes ranging from the development of new materials to the storage of nuclear waste. It is also becoming increasingly evident…
Polyaniline, synthesized by using potassium dichromate as the oxidant, was doped with iodine in order to increase its electrical conductivity. The iodine-doped polyanilines attained a conductivity of 1.83 × 10−3 S/cm, which was about eight orders of magnitude greater than that of intrinsic polyaniline. The iodine-dope…
The kinetics of the isothermal polymerization of acrylic acid were determined utilizing 1H-NMR spectroscopy. The polymerization rate was observed to depend approximately on the \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{3}{2} $\end{document} power of monomer and the \documentclass{article}\pagesty…
It has been revealed using microlensing that a considerable part, possibly more than half, of the dark matter in the halo of our Galaxy consists of objects with a mass spectrum ranging from 0.05 to 0.8 of the solar mass. What is the nature of these objects? There exist two hypotheses. According to one, these are Jupit…
In ab initio calculations of electronic structures, total energies, and forces, it is convenient and often even necessary to employ a broadening of the occupation numbers. If done carefully, this improves the accuracy of the calculated electron densities and total energies and stabilizes the convergence of the iterati…
An analytical theory is presented for the damping of low-frequency adsorbate vibrations via resonant coupling to the substrate phonons. The system is treated classically, with the substrate modeled as a semi-infinite elastic continuum and the adsorbate overlayer modeled as an array of point masses connected to the sur…
We calculate the electronic structure of nm scale InP islands embedded in $Ga_{0.51}In_{0.49}P$. The calculations are done in the envelope approximation and include the effects of strain, piezoelectric polarization, and mixing among 6 valence bands. The electrons are confined within the entire island, while the holes…
The structure of the complex perovskite (PFT), which belongs, according to the literature, to the ferroic species , has been refined by single-crystal and powder x-ray diffraction at room temperature, i.e. within the range of stability of the cubic phase. Attention has been paid to the possible presence of tetragonal…
Cathodoluminescent phosphors excited at low voltages and high current densities often exhibit brightness saturation due to ground state depletion. A two-level model can be used to show that the luminance and saturation behavior of low voltage phosphors can be greatly improved by choosing phosphors with an activator de…
phosphors find applications in dosimetry of ionizing radiations. Phosphors having Dy or Tm activators are high-sensitivity thermoluminescence dosimetry materials, while the phosphors with Eu or Sm activators are the proposed materials for radio-photoluminescence dosimetry. Mechanisms of several processes related to va…
A confocal Raman spectroscopy was used to measure intrinsic stress distribution on the growth surface within individual grains of chemical-vapor-deposited diamond film. Polarization analysis of the Raman line shape revealed that even in high quality (2.8 cm−1 linewidth), free-standing film of 0.6 mm thickness, small r…
We report Cs halide-modified Ga–La sulfide glasses, a new class of chalcohalide glasses with improved fiber-drawing and optical properties suitable for Pr3+-doped fiber amplifiers at 1.3 μm. Cs halide-modified Ga–La sulfide glasses retain the essential characteristics of low phonon-energy and good rare-earth solubilit…
In order to determine the feasibility for a new family of nonlinear four-wave-mixing methods based on resonantly enhanced nuclear polarizations, the enhancement of a singly vibrationally resonant, nondegenerate, nonparametric process is measured using an interferometric method. The measurement shows that the resonant…
The magnetization measurement of systems with the nominal formula (R = Eu, Gd, Tb, Y) has been made. It has been found that and are weak ferromagnets of Dzialoshinsky - Moriya type whereas is an antiferromagnet. The substitution of manganese ions by cobalt ones leads to the appearance of different magnetic states: clu…
In this letter, we present a simplified evaluation method for light-biased photoconductance decay measurements. The measured effective lifetime is shown to be a differential quantity τeff,d, which may differ significantly from the actual effective lifetime τeff. However, the actual effective lifetime can be approximat…
Direct observation of ferroelectric domain structures in LiTa${\mathrm{O}}_{3}$ crystal, without etching or surface coating, has been realized by using environmental scanning electron microscopy in secondary electron emission mode. The new method can nondestructively provide domain contrast image at submicron resoluti…
III–V based magnetic (GaMnAs)/nonmagnetic(AlAs) semiconductor superlattices (SLs) have been grown by low-temperature molecular beam epitaxy. X-ray diffraction measurements show that the SLs have good crystalline quality and abrupt interfaces. The SLs having relatively wide (Ga,Mn)As layers (⩾70 Å) are found to be ferr…
A novel mean-field theory of photoinduced reorientation and optical anisotropy in liquid crystalline side-chain polymers is presented and compared with experiments. The reorientation mechanism is based on photoinduced $\mathrm{trans}\ensuremath{\leftrightarrow}\mathrm{cis}$ isomerization and a multidomain model of the…