Elemental composition of nanoclusters formed by pulsed irradiation with low-energy ions during Ge/Si epitaxy

Multilayer silicon structures with built-in layers of Ge nanoclusters were studied experimentally by Raman light scattering. The built-in layers were formed by the pulsed action of a low-energy beam of intrinsic ions during molecular-beam epitaxy. It is found that the ion-stimulated nucleation and the subsequent growth make it possible to obtain Ge nanoclusters almost free of Si.     

Photoluminescence of liquid-crystal azo derivatives in nanopores

Optics and Spectroscopy - The fluorescence of the nematic liquid crystal n-butyl-n′-methoxyazoxybenzene (BMAOB) in the form of a layer and in porous glasses with pores of different diameter...     

A New Cohomology Theory of Orbifold

Based on the orbifold string theory model in physics, we construct a new cohomology ring for any almost complex orbifold. The key theorem is the associativity of this new ring. Some examples are computed.Both authors partially supported by the National Science Foundation     

Steady-state analytical solutions for the lattice boltzmann equation

A general class of analytical solutions of the lattice Boltzmann equation is derived for two-dimensional, steady-state unidirectional flows. A subset of the solutions that verifies the corresponding Navier-Stokes equations is given. It is pointed out that this class includes, e.g., the Couette and the Poiseuille flow but not, e.g., the basic Kolmogorov flow. For steady-state non-unidirectional flows, first and second order solutions of the lattice Boltzmann equation are derived. Practical consequences of the analysis are mentioned. Differences between the technique applied here and those used in some earlier works are emphasized.     

Synthesis and Raman analysis of 1D-ZnO nanostructure via vapor phase growth

1D-nanostructural zinc oxide (ZnO) with different shapes have been synthesized on p-type Si(1 0 0) and glass substrates via vapor phase growth by heating pure zinc powder at temperatures between 480 and 570 °C. The different ZnO nanostructures depend on the substrates and the growth temperatures. Scanning electron microscopy and X-ray diffraction revealed that a well-aligned nanowires array, which are vertical to the substrate of Si(1 0 0) with 18 sides on their heads, but six sides on their stems, has been formed at 480 °C. Raman study on the ZnO nanostructures shows that the coupling strength between electron and phonon determined by the ratio of the second- to the first-order Raman scattering cross-sections declines with decreasing diameter of the nanowires. However, a little changes of the coupling strength in terms of the width of the nanobelts have been observed.     

On two theorems for flat,affine group schemes over a discrete valuation ring

We include short and elementary proofs of two theorems that characterize reductive group schemes over a discrete valuation ring, in a slightly more general context.     

Application of Pulsed Traveling Hydrogen Arcs for Metal Oxide Reduction

A plasma reactor that has a transient traveling arc has been used to study hydrogen in relation to in-flight reduction of metal oxide particles. Experiments were done to determine the nature of the arc and its interaction with the reactor gas. The lifetime of the excited atomic hydrogen was measured and it was found to be more than 4 ms after the arc had ceased. Powders and tablets of oxides were exposed to the pulsed-arc treated hydrogen and found to react much more rapidly and intensely than when exposed to hot molecular hydrogen. The results suggest that atomic hydrogen will exist throughout the volume of such a reactor for a period that is sufficient to reduce particles of FeO, Cr₂O₃, and TiO₂.     

Proteinases from Carica papaya Latex

Data on the proteinase complex from Carica papaya latex were reviewed. The properties and applications of the domestic preparation cucumazyme and known medicinal preparations based on papaya proteinases (caripazyme, lecozyme, lecopain) were compared.     

Groups in which every non-abelian subgroup is permutable

A subgroupH of a groupG is said to bepermutable ifHX=XH for every subgroupX ofG. In this paper the structure of groups in which every subgroup either is abelian or permutable is investigated. This work was done while the last author was visiting the University of Napoli Federico II. He thanks the “Dipartimento di Matematica e Applicazioni” for its financial support.