Semiempirical theory of turbulence of inhomogeneous flows with body forces

A closed system of equations for the second moments, determining the turbulent transfer in inhomogeneous flows with body forces, is obtained in the local equilibrium approximation. Taking diffusion and convective transfer into account does not present difficulties, since the expressions obtained for the terms containing the fluctuations of the body forces and transfer terms are preserved. The effect of the external forces is considered for two cases: turbulent motion in a stratified medium and conducting flows in a longitudinal magnetic field. In the latter case the external forces are divergenceless and they therefore do not affect the pressure fluctuations. A single-scale model, in which the transverse scale is taken as the scale in the boundary layer, is considered.Translated from Izvestiya Akademii Nauk SSSS, Mekhanika Zhidkosti i Gaza, No. 3, pp. 33–40, May–June, 1985.     

Phosphorescent Ruthenium Complexes with a Nitroimidazole Unit that Image Oxygen Fluctuation in Tumor Tissue

Understanding oxygen fluctuation in a cancerous tumor is important for effective treatment, especially during radiotherapy. In this paper, ruthenium complexes bearing a nitroimidazole group are shown to report the oxygen status in tumor tissue directly. The nitroimidazole group was known to be accumulated in hypoxic tumor tissues. On the other hand, the ruthenium complex showed strong phosphorescence around 600 nm. The emission of ruthenium is quenched instantaneously by molecular oxygen due to energy transfer between triplet states of oxygen and ruthenium complex, but the emission is then recovered by the removal of oxygen. Thus, we could observe oxygen fluctuation in tumor tissue in a real‐time manner by monitoring the phosphorescence of the ruthenium complex. The versatility of the probe is demonstrated by monitoring oxygen fluctuation in living cells and tumor tissue planted in mice. The ruthenium complex promptly penetrated plasma membrane and accumulated in cells to emit its oxygen‐dependent phosphorescence. In vivo experiments revealed that the oxygen level in tumor tissue seems to fluctuate at the sub‐minute timescale.     

Synthesis of TiO<Subscript>2</Subscript> nanotubes using different alkaline media and their applications in photocatalysis and DSSCs

TiO₂ nanotubes (TNTs) were successfully synthesized from different alkaline media (i.e., NaOH and KOH) by using a microwave hydrothermal process. The effects of different alkaline media on the formation of TiO₂ nanotubes and their physicochemical properties were investigated. The phases of different TiO₂ nanostructures were studied by using X-ray diffraction patterns. Morphologies of the nanostructures were observed with a transmission electron microscope. The optical properties of the nanostructures were evaluated through the absorption behavior using UV–Vis diffuse reflectance spectroscopy. The photocatalytic activities of the TiO₂ nanostructures were evaluated by the degradation of methylene blue aqueous dye solution under the simulated solar light irradiation. Similarly, the photovoltaic efficiencies of the prepared samples were investigated by making photo-anode layers in the Dye Sensitized Solar Cells (DSSCs). The results revealed that in comparison to the single layered TiO₂ nanostructures in the DSSC, creation of a double layer structure significantly enhanced the efficiency of DSSC.     

Measuring analogousness in picture fuzzy sets: from picture distance measures to picture association measures

In this paper, we extend the basic distance measure in picture fuzzy sets to the new measures called generalized picture distance measures and picture association measures. Some properties of these measures are examined. An application to clustering problem is given to illustrate applicability of the proposed works.     

Diffusion in multicomponent gaseous mixtures in a model of local thermodynamic equilibrium

Diffusion of chemical elements into an ionized multicomponent gaseous mixture is considered in a model of local thermodynamic equilibrium. A linear dependence of the mass flows of chemical elements and the heat flow on the temperature gradient, mass fractions of the chemical elements, and the electric field is obtained. An example is given of a calculation of the effective diffusion coefficients for a hydrogen-helium mixture.     

TiO2–SiO2 in PEG: A Highly Efficient Green Catalytic System for One‐Pot Synthesis of Benzo[a]xanthen‐11‐ones

Polyethylene glycol was found to be an inexpensive non‐toxic and effective medium for the one‐pot synthesis of benzo[a]xanthen‐11‐ones in the presence of TiO₂–SiO₂ as the catalyst in good to excellent yield. The salient features of this protocol are the simplicity of the procedure, the ready accessibility of the catalyst, its cost effectiveness, and reusable catalyst in relatively short reaction times.     

α,β-Unsaturated acyl cyanide synthesis via triethylamine catalyzed redox cyanation

Stereoselective redox cyanation of alkynyl aldehydes was explored, furnishing (E)-α,β-unsaturated acyl cyanides. This reaction was catalyzed by mild TEA base, as a dual role of Lewis base and Brönsted base. TMSCN treated with TEA was an effective reagent for generating umpolung intermediates from alkynyl aldehydes, and this nucleophilic intermediate can be protonated by equimolar amount of EtOH, promoting the efficient conversion into α,β-unsaturated acyl cyanides. The synthesized acyl cyanides were successfully applied as the synthetic precursors in the iron-catalyzed arylation reactions.     

Prediction error sampling procedure based on dominant Schur decomposition. Application to state estimation in high dimensional oceanic model

Iterative procedure is described to generate patterns of dominant Schur vectors of the system dynamics. Their roles in estimating the filter gain is study. These patterns are produced by several integrations of the model from a set of perturbations. This approach is motivated by a number of interesting results on stability of the filter whose gain is approximated in a subspace of dominant Schur vectors. A simple method for the filter design is presented which is aimed at overcoming the most serious drawback of advanced filtering algorithms for high dimensional systems related to very high computational cost in evaluation of the filter gain.The resulting filter will be compared with the existing ones, showing its relevance from a practical point of view. In order to demonstrate its efficiency, the new filter is tested on various experiments. These experiments include the much studied problem of estimating the solution of the Lorenz system as well as that of assimilating sea surface height observations in a high dimensional oceanic model. It is shown that significant increases in efficiency can be obtained by using this filter and that the proposed filter is very promising for solving realistic assimilation problems in meteorology and oceanography.     

SnSe2 nanoplate-graphene composites as anode materials for lithium ion batteries

Through a solution approach, SnSe(2) nanoplate-graphene composites were prepared and applied as anode materials in lithium ion batteries, showing promising storage performance superior to SnSe(2) nanoplates or graphene alone.     

Random field Ising model and community structure in complex networks

We propose a method to determine the community structure of a complex network. In this method the ground state problem of a ferromagnetic random field Ising model is considered on the network with the magnetic field B_s = +∞, B_t = -∞, and B_i≠s,t=0 for a node pair s and t. The ground state problem is equivalent to the so-called maximum flow problem, which can be solved exactly numerically with the help of a combinatorial optimization algorithm. The community structure is then identified from the ground state Ising spin domains for all pairs of s and t. Our method provides a criterion for the existence of the community structure, and is applicable equally well to unweighted and weighted networks. We demonstrate the performance of the method by applying it to the Barabási-Albert network, Zachary karate club network, the scientific collaboration network, and the stock price correlation network. (Ising, Potts, etc.)