Neurohumoral and metabolic response to exercise in water.

Item does not contain fulltextAtrial natriuretic peptide (ANP) stimulates lipid mobilization and lipid oxidation in humans. The mechanism appears to promote lipid mobilization during exercise. We tested the hypothesis that water immersion augments exercise-induced ANP release and that the change in ANP availability is associated with increased lipid mobilization and lipid oxidation. In an open randomized and cross-over fashion we studied 17 men (age 31+/-3.6 years; body mass index 24+/-1.7 kg/m(2); body fat 17+/-6.7%) on no medication. Subjects underwent two incremental exercise tests on a bicycle ergometer. One test was conducted on land and the other test during immersion in water up to the xiphoid process. In a subset (n=7), we obtained electromyography recordings in the left leg. We monitored gas exchange, blood pressure, and heart rate. In addition, we obtained blood samples towards the end of each exercise step to determine ANP, norepinephrine, epinephrine, lactate, free fatty acids, insulin, and glucose concentrations. Heart rate, systolic blood pressure, and oxygen consumption at the anaerobic threshold and during peak exercise were similar on land and with exercise in water. The respiratory quotient was mildly reduced when subjects exercised in water. Glucose and lactate measurements were decreased whereas free fatty acid concentrations were increased with exercise in water. Water immersion attenuated epinephrine and norepinephrine and augmented ANP release during exercise. Even though water immersion blunts exercise-induced sympathoadrenal activation, lipid mobilization and lipid oxidation rate are maintained or even improved. The response may be explained by augmented ANP release.1 mei 201

Solar Hydrogen Production by Plasmonic Au–TiO₂ Catalysts: Impact of Synthesis Protocol and TiO₂ Phase on Charge Transfer Efficiency and H₂ Evolution Rates

The activity of plasmonic Au–TiO₂ catalysts for solar hydrogen production from H₂O/MeOH mixtures was found to depend strongly on the support phase (anatase, rutile, brookite, or composites thereof) as well as on specific structural properties caused by the method of Au deposition (sol-immobilization, photodeposition, or deposition–precipitation). Structural and electronic rationale have been identified for this behavior. Using a combination of spectroscopic in situ techniques (EPR, XANES, and UV–vis spectroscopy), the formation of plasmonic Au particles from precursor species was monitored, and the charge-carrier separation and stabilization under photocatalytic conditions was explored in relation to H₂ evolution rates. By in situ EPR spectroscopy, it was directly shown that abundant surface vacancies and surface OH groups enhance the stabilization of separated electrons and holes, whereas the enrichment of Ti³⁺ in the support lattice hampers an efficient electron transport. Under the given experimental conditions, these properties were most efficiently generated by depositing gold particles on anatase/rutile composites using the deposition–precipitation technique