Development of silver–metal oxide reactive air braze alloys for electroding PZT ceramics

Existing multi-layer devices using lead-based piezoelectric ceramics utilize an internal electrode that does not bond the ceramic layers. Improvements in device performance and processing could be gained if the electrode also acted as a bond between the ceramic layers. In the current work, the feasibility of brazing lead zirconate titanate (PZT) in ambient conditions utilizing silver-based alloys containing low melting temperature metal oxides was investigated. Wettability, joint fracture strength, and microstructural analyses were conducted for various PZT/silver–metal oxide systems. The metal oxide additions included copper (II) oxide, vanadium pentoxide, lead (II) oxide, and eutectic lead oxide-titanium (IV) oxide. The silver–copper oxide (Ag–CuO) system demonstrated the most potential; exhibiting an apparent contact angle of approximately 64° and an average braze joint fracture strength that was approximately 62% of the monolithic PZT strength. In addition, no significant reaction product formation was observed at the silver/PZT interface. However, a preliminary investigation of multi-layer devices electroded with Ag–CuO alloys indicated a decrease in the resistivity of the brazed PZT by several orders of magnitude.     

Phytochelatin synthase activity as a marker of metal pollution

The synthesis of phytochelatins is catalyzed by γ-Glu-Cys dipeptidyl transpeptidase called phytochelatin synthase (PCS). Aim of this study was to suggest a new tool for determination of phytochelatin synthase activity in the tobacco BY-2 cells treated with different concentrations of the Cd(II). After the optimization steps, an experiment on BY-2 cells exposed to different concentrations of Cd(NO₃)₂ for 3 days was performed. At the end of the experiment, cells were harvested and homogenized. Reduced glutathione and cadmium (II) ions were added to the cell suspension supernatant. These mixtures were incubated at 35 °C for 30 min and analysed using high performance liquid chromatography coupled with electrochemical detector (HPLC-ED). The results revealed that PCS activity rises markedly with increasing concentration of cadmium (II) ions. The lowest concentration of the toxic metal ions caused almost three fold increase in PCS activity as compared to control samples. The activity of PCS (270 fkat) in treated cells was more than seven times higher in comparison to control ones. K_m for PCS was estimated as 2.3 mM.     

Changes in Phenotypes and DNA Methylation of In Vitro Aging Sperm in Common Carp Cyprinus carpio

The purpose of the current study was to analyze phenotypic and functional characteristics of common carp (Cyprinus carpio) spermatozoa during in vitro aging and to investigate whether global DNA methylation is affected by sperm aging. Milt was collected from five individual males, stored in vitro on ice in a refrigerator for up to 96 h post stripping (HPS) and used to fertilize eggs with intervals of 1, 24 and 96 h. Computer-assisted sperm analysis and a S3e Cell Sorter was employed to determine the spermatozoa phenotypic characteristics (motility, velocity, concentration and viability). In addition, pH and osmolality of the seminal fluid and the capacity of the spermatozoa to fertilize, hatching rate and health of the resulting embryos were examined at different aging times. Whole-genome bisulfite sequencing was used to compare the global and gene-specific DNA methylation in fresh and aged spermatozoa. The results demonstrated that spermatozoa aging in common carp significantly affects their performance and thus the success of artificial fertilization. The methylation level at the cytosine-phosphate-guanine (CpG) sites increased significantly with 24 HPS spermatozoa compared to the fresh group at 1 HPS and then decreased significantly at 96 HPS. A more detailed investigation of gene specific differences in the DNA methylation was hindered by incomplete annotation of the C. carpio genome in the public databases.     

Resource Management Based on Dynamic Users Association for Future Heterogeneous Telecommunication Access Infrastructures

In this paper an approach for resource management for Heterogeneous Networks (HetNets) based on the dynamic association of users in sets is proposed. The approach is based on the consideration that in a telecommunication network every access point has the property of limited performance, capacity and service potential. Through the definition of two generalized parameters of the servicing cell a characteristic model of the servicing properties of a HetNet access point is developed. An optimization task is defined for a resource management approach with the goal of “providing user service with the required quality of Service while minimizing servicing costs”. The task is solved via the introduction of a modified ADD/DROP heuristic algorithm. A comparison with two other heuristic algorithms is performed showing some of the advantages of the proposed algorithm such as its low computational complexity, fast convergence and effectiveness of the heuristic procedure. A sample application for transmission power control is presented.     

Parenteral Lipid Emulsions in Guinea Pigs Differentially Influence Plasma and Tissue Levels of Fatty Acids,Squalene, Cholesterol,and Phytosterols

Lipid emulsions are made by mixing vegetable and/or fish oils with egg yolk and contain different types and amounts of fatty acids and sterols. This study assessed the effects of oral diet, soybean oil (SO)-, fish oil (FO)-, a mixture of olive and soybean oil (OOSO)-, and a mixture of fish, olive, coconut, and soybean oil (FOCS)-based emulsions on plasma triacylglycerols and plasma and tissue fatty acid and sterol content following acute and chronic intravenous administration in the guinea pig. Upon acute administration, peak triacylglycerols were highest with SO and lowest with OOSO. Upon chronic administration, the plasma triglyceride levels did not increase in any group over that of the controls. Fatty acid levels varied greatly between organs of animals on the control diets and organs of animals following acute or chronic lipid administration. Squalene levels increased in plasma following acute administration of OOSO, but plasma squalene levels were similar to control in all emulsion groups following chronic administration. Total plasma phytosterol levels were increased in the SO, OOSO, and FOCS groups following both acute and chronic infusions, whereas phytosterols were not increased following FO infusion. Total phytosterol levels were higher in liver, lung, kidney and adipose tissue following SO and OOSO. Levels were not increased in tissues after FO and FOCS infusion. These results indicate that fatty acid and sterol contents vary greatly among organs and that no one tissue reflects the fatty acid or sterol composition of other tissues, suggesting that different organs regulate these compounds differently.     

A Comparison of Word- and Sense-Based Text Categorization Using Several Classification Algorithms

Most of the text categorization algorithms in the literature represent documents as collections of words. An alternative which has not been sufficiently explored is the use of word meanings, also known as senses. In this paper, using several algorithms, we compare the categorization accuracy of classifiers based on words to that of classifiers based on senses. The document collection on which this comparison takes place is a subset of the annotated Brown Corpus semantic concordance. A series of experiments indicates that the use of senses does not result in any significant categorization improvement.     

Concomitant processes in the redox switching of polyaniline

It is shown for the first time that the redox switching of polyaniline (PANI) under voltammetric conditions is accompanied by the following processes: oxidation of PANI by atmospheric oxygen in the range of low potentials (E < 0.2 V); reduction with addition of aniline (post-polymerization) at E > 0.2(5) V, which in the range 0.2(5) < E < 0.5 V compensates entirely for the oxidation over the timescale of the cyclic voltammogram. These processes determine: (a) the existence of the emeraldine (conducting) state in a potential window (instead of at a defined potential); (b) the fundamental asymmetry in the redox behaviour of PANI; (c) the difference in the rates of the oxidation and reduction transients and (d) the dependence of the electrochemical activity of PANI on the pH of the medium.