Nanocomposites of SnO2 and g-C3N4: Preparation,characterization and photocatalysis under visible LED irradiation

Tin dioxide nanoparticles were prepared in the presence of graphitized carbon nitride (g-C₃N₄) forming nanocomposites with different contents of SnO₂ up to 40 %. G-C₃N₄ was synthetized by heating of melamine at 550 °C in the open air and Sn²⁺ ions were precipitated by sodium hydroxide in g-C₃N₄ aqueous dispersions. Resulting mixtures were dried by freezing at ?20 °C and calcined at 450 °C to obtain SnO₂/g-C₃N₄ nanocomposites.The nanocomposites were characterized by common characterization methods in solid state and in their aqueous dispersions using dynamic light scattering (DLS) analysis and photocatalysis. SnO₂ nanoparticles in the nanocomposites were found to have an average size of 4 nm, however, those precipitated without g-C₃N₄ had an average size of 14 nm. Separation of photoinduced electron and holes via heterojunction between SnO₂ and g-C₃N₄ was demonstrated by photocatalytic decomposition of Rhodamine B (RhB) under LED visible irradiation (416 nm) and photocurrent measurements. The most photocatalytically active nanocomposite contained 10 % of SnO₂. Graphitized carbon nitride was assumed to serve as a template structure for the preparation of SnO₂ nanoparticles with a narrow size distribution without using any stabilizing additives.     

Physicochemical Investigation of the Reaction of Components of the Si — Al — O — N — Ti System in the Si3N4 — Al2O3 — AlN — SiO2 — TiN — TiO2 Region. Part 2. Subsystems Si3N4 — AlN,TiN — AlN,Al2O3 — AlN

The reaction of components of the Si — Al — O — N — Ti system in its elements Si ₃N₄ — AlN, TiN — AlN, and Al ₂O ₃ — AlN was investigated by differential thermal and x-ray diffraction analysis. It was established that upon hot pressing mixtures of Si₃N ₄ and AlN (up to 1950°C) free silicon is formed by the decomposition of Si ₃N₄, which reacts with oxygen present as an impurity to form SiO. When TiN reacts with AlN a phase with the spinel structure (Al₂₃O ₂₇N ₅), which can form only in the presence of excess oxygen, appears in addition to the initial components. Spinel is also produced by the reaction of Al ₂O₃ with AlN. In this case a eutectic between Al ₂₃O₂₇N₅ and Al₂O₃ is observed.     

Volatile compounds on the surface and within Iberian dry-cured loin

The profile of volatile compounds from external and internal areas of Iberian dry-cured loin was studied by headspace solid-phase microextraction. Higher levels of 16 volatile compounds (hexane, decane, 3-methylbutanal, several sulphur compounds and some aromatic hydrocarbons) were detected in the outer part of the loins. These differences could be owing to several factors, such as greater exposure to oxygen and dehydration conditions in the surface of the product, which favour oxidation reactions and Strecker degradation of amino acids. Moreover, the addition of spices on the surface and the proximity of a mould layer growing on the surface of the product could also contribute to the higher levels of these compounds on the external layer. However, other sulphur compounds coming from spices showed similar levels on the surface and within the loins. This different behaviour could be a consequence of different diffusion rates depending on the features of the compound and the matrix.     

Fast branch & bound algorithms for optimal feature selection

A novel search principle for optimal feature subset selection using the Branch & Bound method is introduced. Thanks to a simple mechanism for predicting criterion values, a considerable amount of time can be saved by avoiding many slow criterion evaluations. We propose two implementations of the proposed prediction mechanism that are suitable for use with nonrecursive and recursive criterion forms, respectively. Both algorithms find the optimum usually several times faster than any other known Branch & Bound algorithm. As the algorithm computational efficiency is crucial, due to the exponential nature of the search problem, we also investigate other factors that affect the search performance of all Branch & Bound algorithms. Using a set of synthetic criteria, we show that the speed of the Branch & Bound algorithms strongly depends on the diversity among features, feature stability with respect to different subsets, and criterion function dependence on feature set size. We identify the scenarios where the search is accelerated the most dramatically (finish in linear time), as well as the worst conditions. We verify our conclusions experimentally on three real data sets using traditional probabilistic distance criteria.     

Simple On-Line Algorithms for the Maximum Disjoint Paths Problem

In this paper we study the classical problem of finding disjoint paths in graphs. This problem has been studied by a number of authors both for specific graphs and general classes of graphs. Whereas for specific graphs many (almost) matching upper and lower bounds are known for the competitiveness of on-line algorithms, not much is known about how well on-line algorithms can perform in the general setting. The best results obtained so far use the expansion of a network to measure the algorithms performance. We use a different parameter called the routing number that, as we will show, allows more precise results than the expansion. It enables us to prove tight upper and lower bounds for deterministic on-line algorithms. The upper bound is obtained by surprisingly simple greedy-like algorithms. Interestingly, our upper bound on the competitive ratio is even better than the best previous approximation ratio for off-line algorithms. Furthermore, we introduce a refined variant of the routing number and show that this variant allows us, for some classes of graphs, to construct on-line algorithms with a competitive ratio significantly below the best possible upper bound that could be obtained using the routing number or the expansion of a network only. We also show that our on-line algorithms can be transformed into efficient algorithms for the more general unsplittable flow problem.     

Toxicity increases in ice containing monochlorophenols upon photolysis: environmental consequences

The toxic effects of photoproducts formed upon the photolysis of 2- and 4-chlorophenol (CP) frozen solutions in polycrystalline ice phase were determined with a bacterial luminescence test (Vibrio fisheri), and in vitro biomarker assay for dioxin-like effects (inductions of AhR-dependent luciferase in H4IIE-luc cells) and compared to the toxic effects of products of the same photoreaction in aquatic phase. Coupling photoproducts formed in ice samples (3'-chlorobiphenyl-2,4'-diol and 3-chlorobiphenyl-2,2'-diol from 2-CP photolysis and 5-chlorobiphenyl-2,4'-diol from 4-CP photolysis) were found to be more toxic to V. fisheri than parent CPs and elicited significant inductions of dioxin-like effects (the effective concentrations EC50 approximately 3 x 10(-5) mol L(-1) corresponded to known weaker ligands of AhR, such as nonplanar polychlorinated biphenyls or polycyclic aromatic hydrocarbons). To complete the picture, a photoproduct formed from 4-CP (5-chlorobiphenyl-2,4'-diol) was synthesized, and a detailed toxicity assessment with purified compound confirmed the results obtained with irradiated samples. Our findings support a recently proposed model according to which solar radiation can trigger the formation of new types of organic pollutants in polar ice or tropospheric ice cloud particles, presenting possibly greater risk to the environment than the parent compounds.     

n-Alkane content of intramuscular lipids of Iberian fresh ham from different feeding systems and crossbreeding

n-Alkane content of intramuscular lipids (Biceps femoris muscle) of the Iberian pig have been determined. Thirty-four pigs, divided into four groups, based in the feeding system (Montanera, fed on acorns and pasture; and Pienso, fed on a concentrate feed) and in the genotype (Iberian pure pigs; and Iberian crossbred with Duroc 50%) were studied. n-Alkane content of intramuscular lipids has not been affected by neither crossbreeding nor feeding, although the analysis of feeds administered to the pigs showed greater n-alkane values in pasture (consumed by animals in montanera), than in acorns and concentrate feed.     

Enhancement of magnetic losses in hybrid polymer composites with MnZn-ferrite and conductive fillers

Polymer composites (PCs) with a polyurethane (PU) matrix filled with magnetic filler (MnZn ferrite) and hybrid polymer composites (HPCs) consisting of this magnetic filler and various types of conductive fillers (carbon black, carbon fibers, aluminum powder, polypyrrole) are prepared. The matrix structure of a HPC is formed (i) by a polymer filled with conductive filler, which forms the skeleton of an infinite cluster, and (ii) by ferrite particles that are larger than conductive particles. Thus, an HPC represents an ensemble of ferrite particles each of which is surrounded by a conductive medium and can be considered as a “core–shell” structure. The development of a core–shell structure is evidenced by the lower electric percolation threshold in an HPC compared with that in PU filled with conductive filler. Magnetic and dielectric spectra of PCs and HPCs are studied in the frequency range from 1 MHz to 10 GHz. Hybrid systems exhibit a considerable enhancement of magnetic losses compared with PCs. The enhancement of magnetic losses in HPCs is due to the conduction currents that are induced in the conductive shell by a microwave magnetic field.     

GPU-accelerated DXT and JPEG compression schemes for low-latency network transmissions of HD, 2K,and 4K video

Low-latency transmissions of high resolution video such as HD, 2K, or 4K over both Internet and private IP networks have found a foothold in many interactive applications, ranging from collaborative environments in science and medicine to the arts and entertainment industry. In this paper we demonstrate how the power of commodity graphics processing units can be used for efficient implementation of JPEG and DXT compression. We propose an approach to fine-grained parallelization of JPEG compression and the use of auxiliary indexes for efficient decompression, which are backward compatible with the JPEG standard. In-depth performance analysis is provided to show various aspects of the proposed parallelization including the dependency on image content and on various settings of the compression algorithm, as well as the impact of compression for interactive applications in terms of end-to-end latency. The applicability of these compression schemes in medicine and cinematography has also been evaluated using double-blind ABX tests compared with uncompressed video. We describe selected successful real-world deployment use cases based on our open-source implementation within the UltraGrid framework, such as trans-Atlantic 4K interactive video streaming during the CineGrid 2011 workshop. As discussed in the paper, the proposed approaches to parallelization provide sufficient performance even for the future generation of 8K video processing systems, currently limited by availability of camera and display hardware.