No abstract

A simply structured gas diffusion electrode (GDE) was constructed by rolling carbon black and PTFE as a conductive catalyst layer to enhance the producibility of hydrogen peroxide. A Box-Behnken design (BBD) coupled with response surface methodology was employed to assess the individual and interactive effects of the three main independent parameters (pH, current density and air flow rate) on the H 2 O 2 concentration. Analysis of variance (ANOVA) showed a high coefficient of determination value. Optimal operating conditions were a pH value of 4.0, current density of 52 mA cm À2 , and an air flow rate of 55 mL min À1 . The predicted H 2 O 2 concentration under the optimal conditions determined by the proposed model was 309.85 mM, demonstrating the improved GDE without using noble metals and other chemical promoters is a potential method for in situ electrosynthesis of H 2 O 2 . Results also revealed that the current density, air flow rate, and their interaction effect had a significant effect on the H 2 O 2 concentration, whereas changes to the initial pH had no apparent effect. Experiments showed that current density has a direct effect on the decomposition reaction in the electrolytic process.

No abstract

This paper reports the investigation of the aging effects on the preparation of ZnO crystals and films. We have found that the morphology of ZnO films can be optimized by selecting appropriate chemical environments including the types of chemical species and their concentrations, which can regulate the dissolutionrecrystallization process during soaking. Several unique morphologies of ZnO have been obtained from an aqueous solution containing ZnCl 2 and a mixture complex agent (amine and ammonia). From this simple solution system, dense, transparent, thick ZnO films with thicknesses up to 20 µm can be grown at about 90 °C under atmospheric pressure. The components of the film were single-crystalline ZnO lamellas that were self-organized mainly with their c axis parallel to the substrate surface. The current findings reveal that one can purposely optimize morphology, crystallography, and organization to pursue special properties by kinetically controlling the nucleation and crystallization processes.

Blood levels of extracellular nucleotides (e.g. ATP) are greatly increased during heart ischaemia, but, despite the presence of their specific receptors on cardiomyocytes (both P2X and P2Y subtypes), their effects on the subsequent myocardial damage are still unknown. In this study, we aimed at investigating the role of ATP and specific P2 receptors in the appearance of cell injury in a cardiac model of ischaemic/hypoxic stress. Cells were maintained in a modular incubator chamber in a controlled humidified atmosphere of 95% N2 for 16 hrs in a glucose-free medium. In this condition, we detected an early increase in the release of ATP in the culture medium, which was followed by a massive increase in the release of cytoplasmic histone-associated-DNA-fragments, a marker of apoptosis. Addition of either apyrase, which degrades extracellular ATP, or various inhibitors of ATP release via connexin hemichannels fully abolished ischaemic/hypoxic stress-associated apoptosis. To dissect the role of specific P2 receptor subtypes, we used a combined approach: (i) non-selective and, when available, subtype-selective P2 antagonists, were added to cardiomyocytes before ischaemic/hypoxic stress; (ii) selected P2 receptors genes were silenced via specific small interfering RNAs. Both approaches indicated that the P2Y2 and P2χ7 receptor subtypes are directly involved in the induction of cell death during ischaemic/hypoxic stress, whereas the P2Y4 receptor has a protective effect. Overall, these findings indicate a role for ATP and its receptors in modulating cardiomyocyte damage during ischaemic/hypoxic stress.

No abstract

No abstract

A laboratory scale closed-loop cycle system for the complete regeneration of sodium persulfate/sulfuric acid etching solution (SPS) has been developed by anode oxidation of sulfate paired to cathode reduction of copper.