Sustainability of small reservoirs and large scale water availability under current conditions and climate change

Semi-arid river basins often rely on reservoirs for water supply. Small reservoirs may impact on large-scale water availability both by enhancing availability in a distributed sense and by subtracting water for large downstream user communities, e.g. served by large reservoirs. Both of these impacts of small reservoirs are subject to climate change. Using a case-study on North-East Brazil, this paper shows that climate change impacts on water availability may be severe, and impacts on distributed water availability from small reservoirs may exceed impacts on centralised water availability from large reservoirs. Next, the paper shows that the effect of small reservoirs on water availability from large reservoirs may be significant, and increase both in relative and absolute sense under unfavourable climate change

Exploring Current Practices of Pediatric Providers Serving Transgender/Gender Non- Conforming (TGNC) Youth 12 Years of Age and Under in the Washington, Alaska, Montana, Idaho Region

Transgender and gender non-conforming (TGNC) youth 12 years of age and under, often present first to their pediatric primary care providers for needs related to their gender identity. Primary care providers are uniquely positioned to address needs for these individuals and their families. Many primary care providers have no additional training for this special population, especially for pre-pubescent TGNC patients, and have varied levels of comfort and strategies regarding signaling acceptance, screening and assessing practices, referral practices, and discussing gender and physical characteristics topics. This project explores current practices of primary care providers in the Washington, Alaska, Montana, Idaho (WAMI) region who have provided care to TGNC youth. Interviews were conducted with eight (n = 8) primary care providers. Thematic analysis was utilized to guide the analytic process via an adapted deductive approach to coding. The themes we identify reflect current practices of how these eight primary care providers serve individuals in this population and may represent similar themes of providers in other regions

Photoelectrocatalytic removal of color from water using TiO2 and TiO2/Cu2O thin film electrodes under low light intensity

This work describes, photoelectrocatalytic degradation of organic pollutants by using methyl orange (an azo dye) as a model compound. The TiO2 thin film and TiO2/Cu2O composite electrodes were used as semiconductor photo electrodes. Photo catalysis by UV light corresponding to the light intensity range of the solar light was employed with the aim of using renewable and pollution-free energy. Result showed that the rate of removal of color was enhanced when potential bias of 1.5 V was applied. The degradation rate was also increased either in acidic (pH 2) or alkaline (pH 10) conditions. The application of a positive potential higher than the flat-band potential on the TiO2 electrode decreases the rapid charge recombination process, and enhanced the degradation of organic compound. When the TiO2/Cu2O thin film electrode was used, more efficient electron and hole separation was observed in the composite system under very low potential. It is considered that the photo-generated holes migrate towards the interface while the electrons migrate towards TiO2 and then to the back contact transparent fluorine doped tin-oxide-coated glass (TCO), making the behavior of the composite film analogous to that of an n-type semiconductor. In all cases, the kinetics of the photo catalytic oxidation of methyl orange followed a pseudo first order model and the apparent rate constant may depend on several factors such as, the nature and concentration of the organic compound, radiant flux, the solution pH and the presence of other organic substances. KEY WORDS: Photoelectrocatalysis, Titanium dioxide, Cuprous oxide, Composite thin film, Photo electrode  Bull. Chem. Soc. Ethiop. 2008, 22(1), 27-40

A Faster Path to Solar Water Splitting

Finding new wide bandgap light absorbers that are stable in aqueous solutions is a long standing challenge in photoelectrochemical water splitting research. Two papers in this issue describe recent advances in high throughput experimentation that may accelerate the discovery of suitable material

Photocurrent Enhancement by Spontaneous Formation of a p n Junction in Calcium Doped Bismuth Vanadate Photoelectrodes

The application of bismuth vanadate BiVO4 photoelectrodes for solar water splitting is hindered by the poor carrier transport. To overcome this, multiple donor doping strategies e.g. dual doping, gradient doping have been explored. Here, we show for the first time the successful introduction of calcium Ca as an acceptor type dopant into BiVO4 photoelectrodes. Interestingly, instead of generating cathodic photocurrents, the Ca doped BiVO4 photoelectrodes show anodic photocurrents with an enhanced carrier separation efficiency. Hard X ray photoelectron spectroscopy HAXPES shows that this enhancement is caused by out diffusion of Ca during the deposition process, which spontaneously creates a p n junction within the BiVO4 layer. Overall, a significant two fold improvement of the AM1.5 photocurrent is obtained upon Ca doping. This study highlights the importance of controlled doping beyond simply modifying carrier concentration and may enable new device architectures in photoelectrode material

Evaluation of electrodeposited alpha Mn2O3 as a catalyst for the Oxygen Evolution Reaction

alpha Mn2O3 is of interest as a low cost and environmentally benign electrocatalyst for the Oxygen Evolution Reaction OER in the process of water splitting. Mechanically stable alpha Mn2O3 electrodes are prepared by annealing of galvanostatically deposited MnOOHx layers on F SnO2 coated glass. The overpotential eta to achieve a current density of j 10 mA cm2 decreases from 590 to 340 mV with increasing layer thickness. Differential capacitance measurements reveal that this high OER activity can be attributed to the large electrochemically active surface area ECSA , which scales linearly with the thickness of these highly porous and electrolyte permeable films. The oxide layers exhibit a reversible oxidation behavior from Mn III to Mn IV , whereas only about 25 of the Mn III is oxidized to Mn IV before the OER reaction takes off. Although the intrinsic activity is small compared to that of other OER catalysts, such as NiFeOx, the combination of high ECSA and good electrical conductivity of these amp; 945; Mn2O3 films ensures that high OER activities can be obtained. The films are found to be stable for gt;2 h in alkaline conditions, as long as the potential does not exceed the corrosion potential of 1.7 V vs. RHE. These findings show that amp; 945; Mn2O3 is a promising OER catalyst for water splitting device