Water Splitting Photovoltaic-Photoelectrochemical GaAs/InGaAsP - WO3/BiVO4 Tandem Cell with Extremely Thin Absorber Photoanode Structure

We demonstrate highly efficient solar hydrogen generation via water splitting by photovoltaicphotoelectrochemical (PV-PEC) tandem device based on GaAs/InGaAsP (PV cell) and WO3/BiVO4 core/shell nanorods (PEC cell). We utilized extremely thin absorber (ETA) concept to design the WO3/BiVO4 core/shell heterojunction nanorods and obtained the highest efficiencies of photo-induced charge carriers generation, separation and transfer that are possible for the WO3/BiVO4 material combination. The PV-PEC tandem shows stable water splitting photocurrent of 6.56 mA cm-2 under standard AM1.5G solar light that corresponds to the record solar-to-hydrogen (STH) conversion efficiency of 8.1%

Physical activity and cardiovascular disease risk factors among young and middleaged men in urban Mwanza, Tanzania

Background: Cardiovascular diseases (CVD) risk factors are increasing at an unprecedented rate in developing countries. However, fewer studies have evaluated the role of physical activity in preventing CVD in these countries. We assessed level physical activity and its relationship with CVD risk factors among young and middle aged men in a fast growing city of Mwanza in Tanzania. Methods: Physical activity was assessed among 97 healthy men aged 20-50years using Sub-Saharan Africa Activity Questionnaire. An updated compendium of physical activity was used to code the metabolic equivalent. Energy expenditure was calculated using Harris Benedict equation. Anthropometric measurements, blood pressure,  fasting blood glucose and serum lipids were also measured. Results: The mean energy expenditure in this population was 6,466 ± 252 kcal/week. More than half (53.6%) of the participants had energy expenditure of H4,000 kcal/week. Only three (3.1%) had energy expenditure below the recommended 1,000 kcal/week. Except for hypertension, prevalence of CVD risk factors was low in this population; hypertension 23.7%, low HDLcholesterol 10.3%, high LDL-cholesterol 9.3% and obesity 4.1%. Physical activity energy expenditure had an inversely relationship with waist to hip ratio, systolic blood pressure, heart rate, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides and fasting blood glucose. Conclusion: Physical activity energy expenditure was high in this population and was inversely correlated with CVD risk factors. Physical activity may play an important role in the prevention of CVD in this urban population of young and middle aged men

The spatio-temporal development of electron swarms in gases: moment equation analysis and Hermite polynomial expansion

Spatio-temporal development of electron swarms in gases is simulated using a propagator method based on a series of one-dimensional spatial moment equations. When the moments up to a suecient order are calculated, the spatial distribution function of electrons, p(x), can be constructed by an expansion technique using Hermite polynomials and the weights of the Hermite components are represented in terms of the electron diausion coeecients. It is found that the higher order Hermite components tend to zero with time, that is, the normalized form of p(x) tends to a Gaussian distribution. A time constant of the relaxation is obtained as the ratio of the second- and third-order diausion coeecients, D2 3=D3L . The validity of an empirical approximation in time-of-cight experiments that treats p(x) as a Gaussian distribution is indicated theoretically. It is also found that the diausion coeecient is deaned as the derivative of a quantity called the cumulant which quantiaes the degree of deviation of a statistical distribution from a Gaussian distribution