Boosting generation of reactive oxygen and chlorine species on TNT photoanode and Ni/graphite fiber cathode towards efficient oxidation of ammonia wastewater.

Photoelectrocatalytic (PEC) process combining the merits of photocatalysis and electrocatalysis is considered as a promising ammonia oxidation technology for water treatment. However, some key issues, such as the limited in situ generation of oxidants on photoanode, slow mass transfer problem and generation of nitrate/nitrite by-products hinder the further application of PEC process in the treatment of ammonia pollutant. In this study, the graphite felt (GF) cathodes modified by different transition metals (Ni, Fe, Mn, Co, Cu) were screened by physicochemical and photoelectrochemical characterizations. The results show that the Ni-GF cathode with more Ni0 uniformly distributed on the GF surface had the best electrocatalytic activity to generate H2O2. The PEC system composed of 10.0 wt% Ni-GF cathode and optimized titania nanotubes (TNTs) photoanode selectively converted about 96.1% ammonia to N2 within 90 min. Compared with the single TNTs photoanode system, the ammonia oxidation reaction rate constant of the synergistic PEC oxidation system was increased by about two times, which demonstrated the role of the oxidants simultaneously generated on both anode and cathode. The in situ generated reactive oxygen-based oxidants and chlorine-based oxidants interacted together, and ClO• acted a leading role in the ammonia oxidation which were confirmed by quenching and probe experiments. In addition, the contributions of •OH and ClO• were significantly improved in the synergistic PEC oxidation system, compared with the single TNTs photoanode system. Furthermore, the nitrate by-products generated by the ammonia oxidation were further reduced on the Ni-GF cathode. The large amount of active chlorine and active oxygen generated on the electrode diffused into the bulk, effectively overcoming the mass transfer limitation of direct oxidation. Therefore, the developed TNTs photoanode/Ni-GF cathode system can continuously and efficiently convert ammonia to N2 without the formation of nitrate/nitrite by-products.

Gas diffusion electrodes for H2O2 production and their applications for electrochemical degradation of organic pollutants in water: A review.

Nowadays, it is a great challenge to minimize the negative impact of hazardous organic compounds in the environment. Highly efficient hydrogen peroxide (H2O2) production through electrochemical methods with gas diffusion electrodes (GDEs) is greatly demand for degradation of organic pollutants that present in drinking water and industrial wastewater. The GDEs as cathodic electrocatalyst manifest more cost-effective, lower energy consumption and higher oxygen utilization efficiency for H2O2 production as compared to other carbonaceous cathodes due to its worthy chemical and physical characteristics. In recent years, the crucial research and practical application of GDE for degradation of organic pollutants have been well developed. In this review, we focus on the novel design, fundamental aspects, influence factors, and electrochemical properties of GDEs. Furthermore, we investigate the generation of H2O2 through electrocatalytic processes and degradation mechanisms of refractory organic pollutants on GDEs. We describe the advanced methodologies towards electrochemical kinetics, which include the enhancement of GDEs electrochemical catalytic activity and mass transfer process. More importantly, we also highlight the other technologies assisted electrochemical process with GDEs to enlarge the practical application for water treatment. In addition, the developmental prospective and the existing research challenges of GDE-based electrocatalytic materials for real applications in H2O2 production and wastewater treatment are forecasted. According to our best knowledge, only few review articles have discussed GDEs in detail for H2O2 production and their applications for degradation of organic pollutants in water.

G-CSF displays restricted ability to promote Sca-1(+) cardiac stem cell proliferation in vitro.

Granulocyte colony-stimulating factor (G-CSF) is a controversial chemical in cardiac cell therapy. Myocardial homing of mobilized bone marrow-derived cells is thought to play a critical role in observed G-CSF-induced cardiac repair; meanwhile, the activation of proliferative potential of cardiac stem cells (CSCs) residing in the heart is a significant challenge. The present study aims to investigate whether G-CSF receptor is expressed in adult resident Sca-1(+) CSCs and determine the effect of G-CSF treatment on the proliferation of CSCs. For cardiac cells isolation, 12-week-old male C57BL/6 mice were anesthetized in a chamber containing 2.5% isoflurane in oxygen, euthanized by CO2 inhalation and then sacrificed by cervical dislocation. Magnetic-activated cell sorting was employed to acquire highly purified Sca-1(+) CSCs. We found that G-CSF receptor was expressed in adult resident Sca-1(+) CSCs by immunofluorescence staining and Western blotting. Exposure of Sca-1(+) cells to G-CSF in the culture medium for 72 h induced time-dependent but self-limiting cell cycle acceleration with a restricted effect on the CSC proliferation. As a result, it has provided a new insight to focus on the association between cardiac G-CSF therapy and adult resident stem cell activation. It may suggest gaining a deeper insight into the mechanisms of the interaction between CSCs and G-CSF to develop a synergistic strategy based on resident stem cell and G-CSF therapy for heart disease.

Cardiac inotropic rebound effect after washout of acetylcholine is associated with electrophysiological heterogeneity in Langendorff-perfused rabbit heart.

Cardiac electrophysiological heterogeneity related to the washout of acetylcholine (ACh) remains incompletely characterized. The aim of this study was to examine whether positive cardiac inotropic action is associated with electrophysiological heterogeneity between the atrium and the ventricle after ACh perfusion and washout. Epicardial monophasic action potentials (MAPs) from the right ventricle and right atrium, as well as cardiac contractility, were recorded from isolated Langendorff-perfused rabbit hearts using MAP electrodes and a force transducer. The results indicated that rebound positive inotropic actions were induced by ACh washout with adrenaline preconditioning. This effect was accompanied by an increase in MAP amplitude (MAPA) in the right ventricle but not the right atrium. These findings indicate that cholinergic muscarinic stimulation may lead to positive cardiac inotropic action followed by changes in regional electrophysiological heterogeneity between the atrial and ventricular myocardium. Therefore, we hypothesize that electrophysiological heterogeneity is an underlying cause of arrhythmogenesis as well as hemodynamic disturbance elicited by sudden termination of vagus stimulation.

Effects of sawdust-CPAM on textile dyeing sludge dewaterability and filter cake properties.

Sawdust was used as a filter aid for the textile dyeing sludge dewatering in this study. Results showed that sawdust conditioning in conjunction with cationic polyacrylamide (CPAM) presented much better dewaterability than CPAM alone. The optimal sawdust and CPAM dosage for the best dewaterability was found to be 60 wt.% (mass percent) and 15 kg/t DS (dry solid), the time to filter (TTF) and the yield at 90% degree of the filtration completion (YN90) were 5s and 15.6 kg/m(2)h under the conditions, respectively. TTF and YN90 were more appropriate parameters than specific resistance to filtration (SRF) for assessing the sludge dewaterability as affected by physical conditioners. The moisture content of various filter cake layers gradually became the same with the increase of sawdust dosage. The flocculated sludge cake became relatively incompressible after sawdust conditioning. Sawdust acts to maintain the permeability during the compressed filtration by resisting cake compression.

Cardiomyocyte death induced by ischaemic/hypoxic stress is differentially affected by distinct purinergic P2 receptors.

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% N(2) 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 P2Y(2) and P2χ(7) receptor subtypes are directly involved in the induction of cell death during ischaemic/hypoxic stress, whereas the P2Y(4) receptor has a protective effect. Overall, these findings indicate a role for ATP and its receptors in modulating cardiomyocyte damage during ischaemic/hypoxic stress.

[The positive inotropic effect after washout of acetylcholine in isolated rabbit hearts].

AIM: To study the regular pattern and mechanism of positive inotropic effect after washout of ACh (rebound of myocardial contractile force) in isolated rabbit hearts. METHODS: The changes of myocardial contractile force after perfusion and washout of ACh were observed in isolated Langendorff perfused rabbit hearts. RESULTS: Maximum rebound rate induced by ACh of 10(-8)-10(-3) mol/L were 2.20% +/- 1.70%, 6.71% +/- 3.40%, 9.18% +/- 3.54%, 14.16% +/- 3.27%, 4.37% +/- 5.86% and 1.03% +/- 6.86%, respectively. Compared with the ACh of 10(-5) mol/L in control group, adrenaline enhanced rebound of myocardial contractile force, maximum rebound rate in adrenaline group was 29.25% +/- 5.83% (P < 0.05), propranolol reduced rebound, and maximum rebound rate in propranolol group was 5.15% +/- 4.45% (P < 0.05), we had not detected rebound of myocardial contractile force in 800 s after addition ACh in verapamil group. CONCLUSION: In isolated rabbit heart, positive inotropic effect after washout of ACh has relevance to the activities of calcium current channel and beta-adrenergic receptor. Perhaps there are some different aspects in the mechanism of positive inotropic effect between perfusion of high concentration and after washout of ACh.