Single nanowire-based UV photodetectors for fast switching

Relatively long (30 µm) high quality ZnO nanowires (NWs) were grown by the vapor-liquid-solid (VLS) technique. Schottky diodes of single NW were fabricated by putting single ZnO NW across Au and Pt electrodes. A device with ohmic contacts at both the sides was also fabricated for comparison. The current-voltage (I-V) measurements for the Schottky diode show clear rectifying behavior and no reverse breakdown was seen down to -5 V. High current was observed in the forward bias and the device was found to be stable up to 12 V applied bias. The Schottky barrier device shows more sensitivity, lower dark current, and much faster switching under pulsed UV illumination. Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs. The NW was treated with oxygen plasma to improve the switching. The photodetector shows high stability, reversibility, and sensitivity to UV light. The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors

Helmet use and bicycle-related trauma injury outcomes

Background: It is essential to identify factors that predict helmet use, so as to mitigate the injury and mortality from bicycle accidents.Objective: To examine the relationship between helmet use and the bicycle-related trauma injury outcomes among bicyclists with head/neck injury in the US.Methods: Data from the 2002-2012 National Trauma Data Bank were used, including all trauma bicycle riders involved in bicycle-related accidents whose primary reason for the hospital or Intensive Care Unit stay was head or neck injury. Using multiple logistic regression, the association between helmet use, Injury severity score (ISS), length of stay in hospital (HLOS) and Intensive Care Unit (ICULOS), and mortality was examined.Results: Of the 76,032 bicyclists with head/neck injury, 22% worn helmets. The lowest was among Blacks, Hispanics, and <17 years old. Wearing a helmet significantly reduces injury severity, HLOS, ICULOS, and mortality (i.e total and in-hospital). Males had a severe injury, longer HLOS, ICULOS, and higher mortality than female. Blacks and Hispanics had longer HLOS and ICULOS and higher total mortality than Whites, but had a similar chance for in-hospital mortality.Conclusions: More effort is needed to enhance helmet use among at-risk bicycle riders, which may reduce injury severity, HLOS, ICULOS, and mortality

High Temperature conversion of fats: Cracking, gasification, esterification and transesterification

Burning fossil fuels increases the concentration of carbon dioxide in the atmosphere. Alternative sources of energy are necessary to control global warming. Diverse synthetic methods transform vegetable oils and animal fats, inexpensive carbon sources to biofuels. This chapter reviews the main chemical and thermal processes that transform triglycerides into fuels. We collected the most cited and recent scientific publications about transesterification, thermal and catalytic cracking, and gasification reactions and their respective technologies