Materials Literature
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According to the Heisenberg uncertainty principle of quantum mechanics, particles which are localized in space by a bounding potential must have a finite distribution of momenta. This leads, even in the lowest-possible energy state, to vibrations, and thus, to the so-called zero-point energy. For chemically bound hydr…
X-ray diffraction, thermoconductivity and nuclear magnetic resonance experiments have been carried out in order to study the diffusion mechanism of N atoms in the lattice. These experiments reveal that a small number of N atoms which enter the lattice, but do not occupy the octahedral interstitial sites, are mobile at…
We have studied the oxidation of single crystalline Cr(110) films prepared by molecular beam epitaxy (MBE) in the temperature range from 400 K to 700 K. Epitaxial α-Cr 2 O 3 layers in [0001] orientation are formed over the whole temperature range. We monitor the oxidation by X-ray reflectivity measurements providing i…
We have observed ultraviolet upconversion fluorescence from the D3/24 and P3/22 levels of Nd3+ in fluoroindate glass under infrared pumping. It was found that the excitation of a large population in the F3/24 metastable level allows to achieve strong upconversion emissions at 354 and 382 nm. A simple rate equation mod…
Abstract The synthesis of three novel pyrazole‐containing complexing acids, N,N,N′,N ′‐{2, 6‐bis[3‐(aminomethyl)pyrazol‐1‐yl]‐4‐methoxypyridine}tetrakis(acetic acid)( 1 ), N,N,N ′, N ′‐{2, 6‐bis[3‐(aminomethyl)pyrazol‐1‐yl]pyrazine}‐tetrakis(acetic acid) ( 2 ), and N,N,N ′, N ′‐{6, 6′‐bis[3‐(aminomethyl)pyrazol‐1‐yl]‐…
The influence of ambient temperature and applied electric field on the electrical properties of high resistivity (1–30 kΩ cm), semi-insulating (>100 kΩ cm), and insulating (1011–1012 Ω cm) single-crystal 6H–SiC is reported. Current–voltage (I–V) characteristics of lateral metal-semiconductor-metal test structur…
The rheology of solvent-filled polymer brushes under steady and oscillatory shear is studied by Brownian dynamics simulation. The flow field is solved self-consistently with the polymer dynamics. We find that under steady flow the brushes are shear thinning in both normal forces and shear viscosity. During oscillatory…
We developed a dual frequency cholesteric light shutter which utilizes a cholesteric liquid crystal; the dielectric anisotropy of the material changes from positive to negative when the frequency of applied voltage is increased. The shutters are switched to the transparent homeotropic texture by low frequency voltages…
We present the results of comparative inelastic neutron scattering measurements of both amorphous and crystalline silicates. We demonstrate the presence of floppy modes in amorphous silica and potassium disilicate over the energy scale 0--5 meV. A peak is also observed at 5 meV in amorphous silica, which is traditiona…
The critical current of a thin film of the high- ${T}_{c}$ superconductor ${\mathrm{DyBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7}$, when incorporated in a heterostructure in which it is separated from a ferromagnetic underlayer of ${\mathrm{La}}_{2/3}{\mathrm{Sr}}_{1/3}{\mathrm{MnO}}_{3}$ by an undoped ultrathin ${\math…
Magnetic entropy change larger than that of gadolinium has been observed in polycrystalline of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ ( $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.2$ and 0.33) perovskite-type manganese oxide. The large magnetic entropy change produced by the a…
We propose a model in which the time dependence of the photoluminescence intensity of a single nanosize quantum dot under cw excitation conditions shows a sequence of ``on'' and ``off'' periods similar to a random telegraph signal. In our model the off periods are the times when the dot is ionized and the luminescence…
Decorin is a member of the expanding group of widely distributed small leucine-rich proteoglycans that are expected to play important functions in tissue assembly. We report that mice harboring a targeted disruption of the decorin gene are viable but have fragile skin with markedly reduced tensile strength. Ultrastruc…
Among the hypothetical forms of fully covalent carbon lattices with either graphite-like sp2 or mixed sp2/sp3 bonding we investigated the possibility of monocrystals with a hollow structure. We have calculated the structural, elastic and electronic properties of two prototypical face–centered cubic lattices C20 and C2…
A density functional theory is presented describing the isotropic-nematic transition in dispersions of self-assembled linear objects in two dimensions. It is shown that the transition is second order. The auto-correlation function of order parameter fluctuations is also calculated on both sides of the transition point…
A detailed examination of the intermediate-segregation regime of diblock copolymer melts is presented using the incompressible Gaussian chain model and self-consistent field theory (SCFT). We find that the competition between interfacial tension and chain stretching used to describe behavior in the strong-segregation…
Curing characteristics and the curing schedule of an epoxy-terminated polymer (ETP) were investigated using diaminodiphenyl ether (DADPE), diaminodiphenyl sulfone (DADPS), diaminodiphenyl methane (DADPM), and the hardener of a commercial epoxy, two-pack Araldite (Ciba-Geigy), as curing agents. The adhesive strength of…
The present state of the real time holographic recording in amorphous semiconductor films is reviewed including mechanisms, parameters, properties and applications. Effects of the coherent, incoherent and relaxational self- enhancement as well as the influence of the film structure relaxation are considered. Quasi-per…
X-ray absorption spectroscopy (XAS) was used to study the local environment around tungsten and molybdenum ions in BaO-P<SUB>2</SUB>O<SUB>5</SUB>-WO<SUB>3</SUB> and CaO-P<SUB>2</SUB>O<SUB>5</SUB>-MoO<SUB>3</SUB> glasses having different composition of WO<SUB>3</SUB> and MoO<SUB>3</SUB> oxides. The W L<SUB>1,3</SUB> an…
The fundamental absorption edge of amorphous, polycrystalline and crystalline tungsten trioxide (WO<SUB>3</SUB>) thin films obtained by different techniques (thermal evaporation, rf plasma sputtering, chemical gas transport) was investigated. Special attention was paid to correct measurements of absorption values of a…