A microkinetic model of the oxygen reduction reaction (ORR) on Pt(111) under a gaseous H2 and O2 atmosphere is used to predict and explain which compositions of H2 and O2 lead to the fastest rate of water formation for temperatures between 600 and 900 K. For a stoichiometric (2:1) mixture of H2 and O2 the rate-determing step is found to transition from O hydrogenation to O2 H dissociation over ...

Many plants accumulate proline, a compatible osmolyte, in response to various environmental stresses such as water deficit and salinity. In some stress responses, plants generate hydrogen peroxide (H2 O2 ) that mediates numerous physiological and biochemical processes. The aim was to study the relationship between stress-induced proline accumulation and H2 O2 production. Using pharmacological a...

Recent research on tendinopathy has focused on its relationship to programmed cell death. Increased autophagy has been observed in ruptured rotator cuff tendon tissues, suggesting a causal relationship. We investigated whether autophagy occurs in human rotator cuff tenofibroblast death induced by oxidative stress and whether antioxidants protect against autophagic cell death. We used H2 O2 (0.7...

We aimed at evaluating the adequacy of the commonly employed compartmental model for quantitation of cerebral metabolic rate of oxygen (CMRO2) using (15)O-labeled oxygen ((15)O2) and positron emission tomography (PET). Sequential PET imaging was carried out on monkeys following slow bolus injection of blood samples containing (15)O2-oxyhemoglobin ((15)O2-Hb), (15)O-labeled water (H2(15)O), and ...

The kinetics and the mechanism of the selective reduction of nitric oxides (NOx) by hydrogen is studied on a trimetallic Pt± Mo±Co/a-Al2O3 catalyst under oxidising conditions. This system is interesting in view of an exhaust gas control of power plants or lean-burn cars. It can be shown that the NO dissociation is the crucial step, dominating the overall reaction behaviour and that it depends o...

Proton reduction catalysts are an integral component of artificial photosynthetic systems for the production of H2. This perspective covers such catalysts with respect to their tolerance towards the potential catalyst inhibitor O2. O2 is abundant in our atmosphere and generated as a by-product during the water splitting process, therefore maintaining proton reduction activity in the presence of...

The relative contributions to O2 consumption made by the protozoal and bacterial populations present within the rumen were determined by using an open-type oxygen electrode system. Measurements indicated that two separate microbial populations contributed approximately equally to ruminal O2 consumption over the O2 concentration range experienced in situ (0.25 to 1.0 microM). The populations wer...

The reaction between H2 and O2 has been studied in a reflected shock tube apparatus between temperatures of 1662–2097 K and pressures of 400–570 torr with Kr as the diluent gas. O atom atomic resonance absorption spectrometry (ARAS) was used to observe absolute [O]t under conditions of low [H2]0 so that most secondary reactions were negligible. Hence, the observed [O]t was the direct result of ...

Initial attempts to grow N2-fixing Derxia gummosa autotrophically on H2, C 0 2 , O2 and N2 in a closed system yielded variable results. Poor growth was found to be due to rapid O2 depletion and the requirement for an agar surface. In a closed system, C2H2 reduction assays could not be carried out due to complete consumption of H2. Hence a flow-through culturing technique was developed to supply...

Occurrences whereby cnidaria lose their symbiotic dinoflagellate microalgae (Symbiodinium spp.) are increasing in frequency and intensity. These so-called bleaching events are most often related to an increase in water temperature, which is thought to limit certain Symbiodinium phylotypes from effectively dissipating absorbed excitation energy that is otherwise used for photochemistry. Here, we...