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Melting is one of the most studied phase transitions important for atomic, molecular, colloidal, and protein systems. However, there is currently no microscopic experimentally accessible criteria that can be used to reliably track a system evolution across the transition, while providing insights into melting nucleation and melting front evolution. To address this, we developed a theoretical mean-field framework with the normalised mean-square displacement between particles in neighbouring Voronoi cells serving as the local order parameter, measurable experimentally. We tested the framework in a number of colloidal and in silico particle-resolved experiments against systems with significantly different (Brownian and Newtonian) dynamic regimes and found that it provides excellent description of system evolution across melting point. This new approach suggests a broad scope for application in diverse areas of science from materials through to biology and beyond. Consequently, the results of this work provide a new guidance for nucleation theory of melting and are of broad interest in condensed matter, chemical physics, physical chemistry, materials science, and soft matter. [ABSTRACT FROM AUTHOR]

A composition in the form of liquid polymer substance intended for embolization procedures was studied in in vivo experiment. The preparation was injected to rabbits into the femoral artery and abdominal aorta. The polymer composition exhibited properties previously demonstrated in vitro: strong adhesion to the vascular wall, high plasticity sufficient for embolization of the blood vessels, distal distribution, and the absence of toxic effects. The contrast substance remained in the embolus, which simplified its further localization. The agent underwent nether resorption nor organization. Injection of the agent in a volume of 0.1 ml was sufficient for embolization of an artery with a diameter of 0.1 cm. The polymer composition completely obstructed the vessel without inducing perforation of its wall. During the first day of the experiment, a slight infiltration of surrounding tissues with lymphoid cells was observed. By day 7, total dry necrosis of pelvic limb distal to the injection site was diagnosed. Inflammation of the surrounding tissues was shown histologically and was considered as the body response to impaired circulation and necrosis. [ABSTRACT FROM AUTHOR]

The extensive reconstruction of rail production at AO EVRAZ ZSMK in 2012 permitted the production of rails meeting global standards. While around 80% of the rails produced by AO EVRAZ ZSMK are purchased by OAO RZhD, the plan is to expand exports. Experience in producing rails to foreign standards is reported, and the prospects for exports in the near future are discussed. [ABSTRACT FROM AUTHOR]

Work on creating the basis for embolic compositions for the treatment of a wide range of pathologies of various organs was conducted. This basis is a solution of a biocompatible water-insoluble polymer in a biocompatible water-soluble solvent. Formation of the embolus in such an aqueous medium takes place in the transition of the solvent into the aqueous phase and the formation of a solid polymer clot occluding a blood vessel. Criteria for selection of the polymer and the solvent for the basis were formulated, and a number of polymers and solvents that meet these criteria were selected for further research. Research on the solubility of the selected polymers in solvents was carried out, and the rheoviscometric characteristics of polymer solutions, as well as parameters of solid emboli formation of polymer solutions in aqueous media, were found. The solution of cellulose acetate plasticized with OPADRY CA 500F190000 polyethylene glycol in dimethylsulfoxide with concentration of no less than 60 g/L was recognized as optimal for further studies. [ABSTRACT FROM AUTHOR]

We used a combination of optically-detected x-ray absorption spectroscopy with molecular dynamics simulations to explore the origins of light emission in small (5 nm to 9 nim) Ge nanoparticles. Two sets of nanoparticles were studied, with oxygen and hydrogen terminated surfaces.Weshow that optically-detected x-ray absorption spectroscopy shows sufficient sensitivity to reveal the different origins of light emission in these two sets of samples. We found that in oxygen terminated nanoparticles its the oxide-rich regions that are responsible for the light emission. In hydrogen terminated nanoparticles we established that structurally disordered Ge regions contribute to the luminescence. Using a combination of molecular dynamics simulations and optically-detected x-ray absorption spectroscopy we show that these disordered regions correspond to the disordered layer a few Å thick at the surface of the simulated nanoparticle [ABSTRACT FROM AUTHOR]

Modern telecommunications rely on the transmission and manipulation of optical signals. Optical amplification plays a vital part in this technology, as all components in a real telecommunications system produce some loss. The two main issues with present amplifiers, which rely on erbium ions in a glass matrix, are the difficulty in integration onto a single substrate and the need of high pump power densities to produce gain. Here we show a potential organic optical amplifier material that demonstrates population inversion when pumped from above using low-power visible light. This system is integrated into an organic light-emitting diode demonstrating that electrical pumping can be achieved. This opens the possibility of direct electrically driven optical amplifiers and optical circuits. Our results provide an alternative approach to producing low-cost integrated optics that is compatible with existing silicon photonics and a different route to an effective integrated optics technology. [ABSTRACT FROM AUTHOR]

This article describes heat-resistant thermally insulating concrete mixtures and products with phosphate and aluminate binders, their properties, and the main processes used to make them. The thermophysical properties required of thermal insulation are obtained together with an increase in its strength thanks to the production of denser but less heat-conducting concretes with fillers composed of aluminum microspheres. [ABSTRACT FROM AUTHOR]

Serine/threonine protein kinase CK2 controls vast variety of fundamental processes in cell life; however, despite long period of study, its functional role is not completely determined. CK2 has a significant pathogenic potential and its activity is strictly associated with the development of various kinds of disorders. There are a growing number of facts that inhibitors of CK2 could be used as pharmaceutical agents for the cancer treatment, viral infections, and inflammatory diseases. In this article, we report structural and biological data on the novel synthetic flavonol derivatives, 3-hydroxy-4′-carboxyflavones, possessing a high inhibitory activity toward CK2. With the aid of combinatorial organic synthesis, molecular modeling techniques and biochemical in vitro tests, we studied the structure-activity relationships of flavonol derivatives and developed binding model describing their key intermolecular interactions with the CK2 ATP-binding site. Obtained data show that the synthetic 3-hydroxy-4′-carboxyflavones possess the highest activity among flavonol inhibitors of CK2 known till date. [ABSTRACT FROM AUTHOR]

The structure and the electrical and magnetic properties of Mn-implanted Si, which exhibits ferromagnetic ordering at room temperature, are studied. Single-crystal n- and p-type Si wafers with high and low electrical resistivities are implanted by manganese ions to a dose of 5 × 1016 cm−2. After implantation and subsequent vacuum annealing at 850°C, the implanted samples are examined by various methods. The Mn impurity that exhibits an electric activity and is incorporated into the Si lattice in interstitial sites is found to account for only a few percent of the total Mn content. The main part of Mn is fixed in Mn15Si26 nanoprecipitates in the Si matrix. The magnetization of implanted Si is found to be independent of the electrical resistivity and the conductivity type of silicon and the type of implanted impurity. The magnetization of implanted Si increases slightly upon short-term postimplantation annealing and disappears completely upon vacuum annealing at 1000°C for 5 h. The Mn impurity in Si is shown to have no significant magnetic moment at room temperature. These results indicate that the room temperature ferromagnetism in Mn-implanted Si is likely to be caused by implantation-induced defects in the silicon lattice rather than by a Mn impurity. [ABSTRACT FROM AUTHOR]

This paper describes the possibility of increasing the efficiency of methods for identifying and evaluating various objects by their descriptions transformed into a geometric tree structure with parameters corresponding to certain values of the generalized golden proportion. Processing these descriptions with the help of the mathematical apparatus of the generalized golden proportion permits one to penetrate their structure to deeper levels, and reveal and evaluate the interstructural connections between their essential signs. The graphic-analytic images of trees can be placed on descriptions and used as additional identification signs. The method can be performed with the help of known hardware and software tools. [ABSTRACT FROM AUTHOR]

Abstract With a view to creating Si LEDs, the structural and luminescent properties of SiOxNy films containing Si nanocrystals in the SiOxNy matrix are studied experimentally. It is found that the film structure (nanocrystal size and concentration, the presence of an amorphous phase, etc.) and the spectrum and intensity of photoluminescence (PL) and electroluminescence (EL) are strongly dependent on the Si stoichiometric excess δ and annealing conditions. At δ≈ 10%, unannealed films are amorphous and contain Si clusters of size < 2 nm, as deduced from the TEM and microdiffraction data obtained. Annealing at 800–1000°C for 10–60 min produces Si crystals 3–5 nm in size with a concentration of ≈1018 cm−3. The annealed films exhibit room-temperature PL and EL over the wavelength range 400–850 nm with intensity peaks located at 50–60 and 60–70 nm, respectively. The PL and EL spectra are found to be qualitatively similar. This suggests that both the PL and the EL should be associated with the formation of luminescent centers at nanocrystal–matrix interfaces and in boundary regions. However, the two phenomena should differ in the mechanism by which the centers are excited. With the EL, excitation should occur by impact processes due to carrier heating in high electric fields. It is found that as δ increases, so does the proportion of large amorphous Si clusters with a high density of dangling bonds. This enhances nonradiative recombination and suppresses luminescence. [ABSTRACT FROM AUTHOR]

We prove a theorem that describes P-faithful partially ordered sets. [ABSTRACT FROM AUTHOR]

The results of an investigation of the transformation of C[sub 60] fullerite to diamond under pressure through intermediate three-dimensionally polymerized and amorphous phases are reported. It is found that treatment of fullerite C[sub 60] at pressures 12–14 GPa and temperatures ∼1400 °C produces a nanocrystalline graphite–diamond composite with a concentration of the diamond component exceeding 50%. At lower temperatures (700–1200 °C) nanocomposites consisting of diamondlike (sp[sup 3]) and graphitic (sp[sup 2]) amorphous phases are formed. The nanocomposites obtained have extremely high mechanical characteristics: hardness comparable to that of best diamond single crystals and fracture resistance two times greater than that of diamond. Mechanisms leading to the transformation of C[sub 60] fullerite into diamond-based nanocomposites and the reasons for the high mechanical characteristics of these nanocomposites are discussed. © 1999 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Using a combination of experimental Raman, FTIR, UV–VIS absorption and emission data, together with the corresponding DFT calculations we propose the mechanism of modification of the folic acid specifically under the hydrothermal treatment at 200 °C. We established that folic acid breaks down into fragments while the pteridine moiety remains intact likely evolving into 6-formylpterin with the latter responsible for the increase in fluorescence emission at 450 nm. The results suggest that hydrothermal approach can be used for production of other purpose-engineered fluorophores. [ABSTRACT FROM AUTHOR]

We investigated light emission of hydrothermally treated citric acid and ethylenediamine (EDA) with various precursor ratios using gel-electrophoresis. We show that this relatively simple approach can deliver significant insights into the origins of photoluminescence. We found that products of the synthesis consist of both positively and negatively charged species and exhibit large dispersion in electrophoretic mobility (i.e. charge-to-size ratio). We observed that despite the large dispersion of the reaction products the blue light emission is confined to discrete bands clearly identifiable in the gel. We demonstrate clear evidence that this emission originates from the negatively charged light molecular fraction with the highest mobility which shows no excitation-dependent light emission. This molecular fluorophore exhibits spectral characteristics similar to previously reported 1,2,3,5-tetrahydro-5-oxo-imidazo[1,2-a]pyridine-7-carboxylic acid (IPCA). Secondary gel electrophoresis run performed on the bands extracted from the first run indicates that no further separation takes place. On the basis of our experimental results, we conclude that relatively stable binding exists between IPCA and EDA-derived product. Thus, the products of the reaction contain IPCA both in molecular form and in complexes with EDA-derived products. We conclude that excitation-dependent emission is related to the fluorophore binding to the positively charged EDA-derived products with a positive charge. [ABSTRACT FROM AUTHOR]

Synthesis of hydrophobic luminescent carbon nanostructures in non-aqueous solution has been performed. The system consisted of hexane as nonpolar “oil” phase, nonionic polyoxyethylene (4) lauryl ether (Brij L4) as a surfactant, and either water or dextran sulfate aqueous solution as a polar phase. Carbon nanodots (CND) with a particle size of 5.0 ± 0.7 nm were formed by solvothermal treatment at 180 °C of two- (hexane-Brij L4) and three-component (hexane-Brij L4-aqua solutions) systems. It was found that CND with blue-green-yellow photoluminescence (PL) with linear dependence of emission peak position on excitation wavelength and stability of PL over at least 3 weeks were formed from Brij L4. We found that using small volume of water as the third component helps to reorganize Brij L4 molecules which results in CND PL intensity increase by a factor of 1.5 and quantum yield increase from 2.0 to 2.6% compared to CND from the two-component micellar system. Replacing water with dextran sulfate solution resulted in a lower quantum yield to 2.2%. Thus, addition of small amount of water clearly shows an effect of molecular level organization on properties of CND and results in enhanced quantum yield.ᅟ [ABSTRACT FROM AUTHOR]