Comparison between base metals and platinum group metals in nitrogen, M codoped TiO 2 (M= Fe, Cu, Pd, Os) for photocatalytic removal of an organic dye in water

The photocatalytic performance of a number of nonmetal and metal codoped TiO2 for the degradation of eosin yellow under simulated solar radiation was investigated. The synthesised materials were characterised by FTIR, Raman spectroscopy, XRD, DRUV-Vis, SEM, and TEM.The N, metal codoped TiO2 containing 0.5 wt.% of the metal consisted mainly of the anatase phase, with a particle size range of 15–28 nm. The particles were largely spherical and shifted the absorption edge well into the visible region. Band gap reduction was more pronounced for the N, PGM codoped TiO2 compared to N, base metal codoped samples. Codoping led to an enhancement in the photocatalytic activity of the materials for the degradation of eosin yellow. N, Pd codoped TiO2 was the most effective photocatalyst (99.9% dye removal) while N, Cu codoped TiO2 showed the least activity (25.5% removal). The mechanism for the photocatalytic enhancement was proposed on the basis of formation of an electron deficient Schottky barrier at the semiconductor-metal interface, which acts as an electron sink and thus retards electron-hole recombination. It was shown that the ability of the photocatalyst to degrade the dye depends on the nature and type of the metal dopant in the codoped TiO2 system

A new role of AMP-activated protein kinase in regulating proliferation of mesenchymal stem cells

Purpose: Natriuretic peptides (NPs) administered during early reperfusion are protective in models of myocardial infarction. A previous study examining the endogenous components of B-type natriuretic peptide (BNP) protection of reperfused myocardium, implicated both sarcolemmal (s) KATP and mitochondrial (m) KATP channels. The indirect evidence characterising the relationship between BNP signalling and KATP was obtained using sulphonylurea receptor inhibitors in a rat isolated heart model of ischaemia-reperfusion injury. Here we seek to further examine the relationship between NPs and sKATP openings using single channel electrophysiology. Given our previous findings and the overarching consensus that cardioprotective autacoids open KATP channels, it was hypothesised that NPs elicit sKATP opening. Methods: Cardiomyocyte isolation. Left ventricular cardiomyocytes were isolated from male Sprague-Dawley rat hearts subjected to enzymatic digestion with Liberase Blendzyme DL. Cardiomyocytes were cultured overnight in Medium 199, prior to patch clamp. Single channel patch clamp. Single channel recordings at room temperature (22°C) were made from cell attached patches bathed in Na+ Locke, pH 7.2. The recording pipette contained high KCl (140 mM), pH 7.2. Recordings (45 sec) were made over a range of patch potentials (0, -30, -60, -90, -120 mV), in the absence (control) and in the presence of bath applied BNP (10, 100 nM and 1 µM), pinacidil (200 µM) or pinacidil vehicle (DMSO, 0.25%). Recordings were also made with BNP and pinacidil applied concomitantly. Data are mean ± S.E.M. Results: The current voltage relationship of sKATP under control conditions was linear at –ve patch potentials, the mean conductance being 52.9 ± 1.8 pS (n = 18 hearts, n = 35 cells). Pinacidil caused a four fold increase in sKATP open probability compared to control. Mean channel conductance in the presence of pinacidil was 59.9 ± 1.9 pS (n = 16 hearts, n = 44 cells). Interestingly BNP at all concentrations had negligible effects on sKATP open probability and unitary conductance. However, BNP at all concentrations and patch potentials inhibited pinacidil induced sKATP openings, restoring channel open probability to baseline. Conclusion: These data illustrate the inhibitory effect of NP signalling on sKATP function in the cardiomyocyte under normoxia. They are concordant with the inhibitory effect of atrial NP on KATP in the pancreatic beta cell, but are in apparent conflict with the current cardioprotection paradigm. However, differential effects on sKATP and mKATP and the effects of hypoxia-reoxygenation require further exploration