Wettability of Calcium Fluoride by V-, Nb-, and Cr-Containing Liquid Alloys

The wetting of calcium fluoride by liquid metal alloys containing 10-50 mass% of chemically active metals (vanadium, niobium, and chromium) was studied by the sessile drop method in vacuum at 700-1350°C. At temperatures above 900°C these alloys did not wet calcium fluoride. The wetting angle was above 90deg;. This is explained by the formation of volatile reaction products at the interface between calcium fluoride and the liquid metal alloys.     

Dimensional properties of graphs and digital spaces

Many applications of digital image processing now deal with three- and higher-dimensional images. One way to represent n-dimensional digital images is to use the specialization graphs of subspaces of the Alexandroff topological space ⁿ (where denotes the integers with the Khalimsky line topology). In this paper the dimension of any such graph is defined in three ways, and the equivalence of the three definitions is established. Two of the definitions have a geometric basis and are closely related to the topological definition of inductive dimension; the third extends the Alexandroff dimension to graphs. Diagrams are given of graphs that are dimensionally correct discrete models of Euclidean spaces, n-dimensional spheres, a projective plane and a torus. New characterizations of n-dimensional (digital) surfaces are presented. Finally, the local structure of the space ⁿ is analyzed, and it is shown that ⁿ is an n-dimensional surface for all n1.     

ZnO ultra-fine powders and films: hydrothermal synthesis,luminescence and UV lasing at room temperature

Zinc oxide ultra-fine crystalline powders and polycrystalline films of high optical quality were synthesized under soft hydrothermal conditions. The phase composition, crystal morphology, and luminescent properties of submicron ZnO powders and films were studied depending on synthesis conditions (system composition, precursor kind, solvent type and concentration, temperature). For the systems containing metallic zinc, the ZnO growth mechanism was suggested. The most intensive UV luminescence and the highest values of I_UV/I_VIS were observed for polycrystalline films grown on Zn substrates. Low-threshold UV lasing at room temperature was found for ZnO-films, grown in hydrothermal systems with hydroxide or halide solutions as solvents, E _th = 1–5 MW/cm². The lowest threshold was observed on the ZnO films grown using LiOH as a solvent and zinc nitrate as ZnO-precursor. Clear mode structures with line-width 0.3 nm are characteristic of the lasing spectra.     

What does integrability of finite-gap or soliton potentials mean?

In the example of the Schr?dinger/KdV equation, we treat the theory as equivalence of two concepts of Liouvillian integrability: quadrature integrability of linear differential equations with a parameter (spectral problem) and Liouville's integrability of finite-dimensional Hamiltonian systems (stationary KdV equations). Three key objects in this field-new explicit Psi-function, trace formula and the Jacobi problem-provide a complete solution. The Theta-function language is derivable from these objects and used for ultimate representation of a solution to the inversion problem. Relations with non-integrable equations are also discussed.     

CdTe nanoparticles display tropism to core histones and histone-rich cell organelles

The disclosure of the mechanisms of nanoparticle interaction with specific intracellular targets represents one of the key tasks in nanobiology. Unmodified luminescent semiconductor nanoparticles, or quantum dots (QDs), are capable of a strikingly rapid accumulation in the nuclei and nucleoli of living human cells, driven by processes of yet unknown nature. Here, it is hypothesized that such a strong tropism of QDs could be mediated by charge-related properties of the macromolecules presented in the nuclear compartments. As the complex microenvironment encountered by the QDs in the nuclei and nucleoli of live cells is primarily presented by proteins and other biopolymers, such as DNA and RNA, the model of human phagocytic cell line THP1, nuclear lysates, purified protein, and nucleic acid solutions is utilized to investigate the interactions of the QDs with these most abundant classes of intranuclear macromolecules. Using a combination of advanced technological approaches, including live cell confocal microscopy, fluorescent lifetime imaging (FLIM), spectroscopic methods, and zeta potential measurements, it is demonstrated that unmodified CdTe QDs preferentially bind to the positively charged core histone proteins as opposed to the DNA or RNA, resulting in a dramatic shift off the absorption band, and a red shift and decrease in the pholuminescence (PL) intensity of the QDs. FLIM imaging of the QDs demonstrates an increased formation of QD/protein aggregates in the presence of core histones, with a resulting significant reduction in the PL lifetime. FLIM technology for the first time reveals that the localization of negatively charged QDs to their ultimate nuclear and nucleolar destinations dramatically affects the QDs' photoluminescence lifetimes, and offers thereby a sensitive readout for physical interactions between QDs and their intracellular macromolecular targets. These findings strongly suggest that charge-mediated QD/histone interactions could provide the basis for QD nuclear localization downstream of intracellular transport mechanisms.     

Phase Equilibria in the Pr - Re - B System

X-ray diffraction methods have been applied to the component interaction in the system Pr - Re - B. Isothermal sections of the phase diagram have been constructed for 600°C (region of more than 33 at.% Pr) and 800°C (region less than 33 at.% Pr). The previously known borides Pr₂Re₃B₆, Pr₈Re_13–x B₁₂, Pr₇(Re₄B₄)₆ are confirmed, which have specific structural types. A new ternary compound has been found, Pr₃ReB₆ (structure not determined).__________Translated from Poroshkovaya Metallurgiya, Nos. 1–2(441), pp. 46–51, January–February, 2005.     

Preparation of aluminum oxide coating on carbon/carbon composites using a new detonation sprayer

A new multi-chamber cumulative detonation sprayer (MCDS) was applied to fabricate an aluminum oxide coating on carbon/carbon composites. MCDS provides heating and acceleration of ceramic micropowders by means of combustible gas mixture detonation products with a frequency of 20 Hz and above. The ceramic aluminum oxide particle kinetic energy ensures the destruction of the weakened areas on the carbon-carbon composite material surface and the incorporation of these particles into the surface layer. The following powder particles decelerate on the already fixed particles and form a ceramic coating. The formed aluminum oxide coating is characterized by high hardness and low porosity (<1%). MCDS provides the formation of a high-quality ceramic layer, which can also serve as the basis for the formation of protective heat-resistant coatings.     

Propagation of longitudinal and bulk waves in shock-loaded transversally isotropic single crystals

The paper is present 3D numerical simulation data on elastoplastic deformation in auxetic single crystals with account of anisotropic pressure. The use of anisotropic pressure allows us to demonstrate the absence of shock wave splitting into an elastic precursor and a plastic wave in a Zn single crystal in the loading direction [0001]. This effect in Zn single crystals is observed in full-scale experiments at any loading rate in the [0001] direction. It is shown that anisotropic pressure should be entered into mathematical models of materials whose elastic properties are characterised by five and more independent elastic constants and hence by bulk compression anisotropy. The use of isotropic pressure in simulating the deformation of such materials leads to nonphysical results.     

Generating and accepting P systems with minimal left and right insertion and deletion

In this paper we investigate the operations of insertion and deletion performed at the ends of a string. We show that using these operations in a P systems framework (which corresponds to using specific variants of graph control), computational completeness can even be achieved with the operations of left and right insertion and deletion of only one symbol, both in the generating as well as in the accepting case.