Numerical simulation of atmospheric pollutant dispersion in an urban street canyon: Comparison between RANS and LES

Prediction accuracy of pollutant dispersion within an urban street canyon of width to height ratio W/H=1 is examined using two steady-state Reynolds-averaged Navier–Stokes (RANS) turbulence closure models, the standard k–ε and Reynolds Stress Model (RSM), and Large Eddy Simulation (LES) coupled with the advection–diffusion method for species transport. The numerical results, which include the statistical properties of pollutant dispersion, e.g. mean concentration distributions, time-evolution and three-dimensional spreads of the pollutant, are then compared to wind-tunnel (WT) measurements. The accuracy and computational cost of both numerical approaches are evaluated. The time-evolution of the pollutant concentration (for LES only) and the mean (time-averaged) values are presented. It is observed that amongst the two RANS models, RSM performed better than standard k–ε except at the centerline of the canyon walls. However, LES, although computationally more expensive, did better than RANS in predicting the concentration distribution because it was able to capture the unsteady and intermittent fluctuations of the flow field, and hence resolve the transient mixing process within the street canyon.     

Oral contraceptives and androgenicity: Influences on visuospatial task performance in younger individuals.

The current study investigated whether the androgenic activity of oral contraceptives (OC) mediates performance on sexually dimorphic cognitive tasks in 155 younger individuals. Participants were categorized by hormonal contraceptive use (user vs. nonuser) and the androgenic activity of each OC (OC generation). OC generation was determined based on previous research in which users are grouped based on the type of progestin contained in each OC. Cognitive tasks included the mental rotation task (MRT) and a recognition memory task. In addition, we examined the correlates of both menstrual cycle phase and OC use, such as mood, premenstrual syndrome, depression, blood pressure, and body fat using standardized measures. The main result was that OC androgenicity influenced MRT performance. Second generation OCs are the most androgenic. Thus, MRT performance was best in these OC users as compared to third generation users, Yasmin users and nonusers. On the other hand, Yasmin, a newer generation of OC, contains an "antiandrogenic" progestin, dropirenone. Yasmin users not only performed more poorly on the MRT in comparison to second and third generation pill users, but they performed significantly worse than OC nonusers. Results show that the androgenic activity in OCs influences MRT performance in the presence of static estrogen levels. Overall, the resulting pattern is consistent with a broad range of results demonstrating that visuospatial performance may be enhanced in women who are exposed to androgenic treatments. Furthermore, visuospatial performance is hindered with the introduction of antiandrogenic preparations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluating a novice driver and pre-driver road safety intervention

Intervention or evaluation studies represent a small proportion of traffic psychology research. The current study evaluated the effectiveness of a road safety intervention by measuring attitudes toward unsafe driving behaviors and risk perception. A sample of high school students (n = 133) participated in a road safety intervention program focusing on attitudes and risk perceptions of young people as novice drivers, pre-drivers, and passengers. This sample was compared with a matched sample of students who did not take the program (n = 172) on their attitudes and perceived risk toward unsafe driving, both prior to the program (T1), immediately after the program (T2), and at 6-week follow-up (T3). While no changes in attitudes toward unsafe driving were found for the control group, the intervention group reported riskier attitudes toward unsafe driving behaviors from T1 to T2 and T3. No differences were found from T1 to T3 in perceived risk toward unsafe driving for either the intervention or control groups. Implications of the study include encouraging a higher rate of road safety program evaluations, leading to better understanding of the effectiveness of road safety intervention programs and how they may be designed and delivered to ensure lower engagement in unsafe driving behaviors by young drivers.     

Controlled Release of a Dual Zinc-Sensing and Gene Regulating Small Molecule from DNA Micelles

Intracellular zinc ions are essential for various biological cell processes and are often dysregulated in many diseases de-pending on their location, protein binding affinity, and concentration in the cell. Due to their prevalence in diseases, it is important to not only effectively sense but chelate the often excess amount of zinc in a cell to alleviate further disease progression. N, N, N′, N′-tetrakis (2-pyridinylmethyl)-1,2-ethanediamine (TPEN) is a selective zinc chelator but its water-insoluble nature and general cytotoxicity limit its therapeutic potential. To address these challenges, TPEN loaded nucleic acid nanocapsules (TL-NANs) were synthesized, and its dual ability to sense and suppress zinc levels intracellularly were evaluated. Additionally, TL-NANs were incubated in lung cells and shown to down regulate Eotaxin, a protein up-regulated during asthma, at significantly reduced concentrations of TPEN showcasing the therapeutic potential of this drug for asthma.     

Synchrotron‐based microprobe investigation of impurities in raw quartz‐bearing and carbon‐bearing feedstock materials for photovoltaic applications

Using synchrotron‐based analytical microprobe techniques, we determine micrometer‐scale elemental composition, spatial distribution, and oxidation state of impurities in raw feedstock materials used in the photovoltaic industry. Investigated Si‐bearing compounds are pegmatitic quartz, hydrothermal quartz, and quartzite. Micrometer‐scale clusters containing Fe, Ti, and/or Ca are frequently observed at structural defects in oxidized states and in bulk concentrations equivalent to inductively coupled plasma mass spectroscopy measurements. Investigated C‐bearing compounds are pine wood, pine charcoal, and eucalyptus charcoal. Clustered metals are observed only in the charcoal samples. Impurity clustering implies that industrial processing could be adapted to take advantage of this “natural gettering” phenomenon, expanding the usable range of raw feedstock materials to dirtier, cheaper, and more abundant ones, currently underexploited for solar‐grade silicon production. Copyright © 2011 John Wiley & Sons, Ltd.     

Factors affecting renewable energy technology adoption policies of 50 states and district of Columbia in the USA

Clean Technologies and Environmental Policy - Renewable energy policies and adoption of new renewable energy technologies in different states of the USA are not uniform. The factors affecting the...     

Growth of titania and tin oxide from Ti2SnC via rapid thermal oxidation in air for lithium-ion battery application

Herein, we report the synthesis of TiO₂–SnO₂–C/carbide hybrid electrode materials for Li-ion batteries (LIBs) via two different methods of controlled oxidation of layered Ti₂SnC. The material was partially oxidized in an open-air furnace (OAF) or using a rapid thermal annealing (RTA) approach to obtain the desired TiO₂–SnO₂–C/carbide hybrid material; the carbide phase encompassed both residual Ti₂SnC and TiC as a reaction product. We tested the oxidized materials as an anode in a half cell to investigate their electrochemical performance in LIBs. Analysis of the various oxidation conditions indicated the highest initial lithiation capacity of 838 mAh/g at 100 mA/g for the sample oxidized in the OAF at 700°C for 1 h. Still, the delithiation capacity dropped to 427 mAh/g and faded over cycling. Long-term cycling demonstrated that the RTA sample treated at 800°C for 30 s was the most efficient, as it demonstrated a reversible capacity of around 270 mAh/g after 150 cycles, as well as a specific capacity of about 150 mAh/g under high cycling rate (2000 mA/g). Given the materials’ promising performance, this processing method could likely be applied to many other members of the MAX family, with a wide range of energy storage applications.     

Initial power measurements for a family of novel vertical-wheel bioreactors

The purpose of this investigation was to develop an initial set of Power number versus Reynolds number results for a family of vertical-wheel bioreactors. These bioreactors are increasingly being used for the manufacture of cells for cell therapy but have not been characterized according to this approach. A novel gravimetric method to measure power was used, and the validity of this method was assessed by measuring power for a standard stirred tank bioreactor with a Rushton impeller. The results of the gravimetric method were found to closely match those derived from traditional methods. The validated method was then used to measure the power draw and develop an initial set of Power number versus Reynolds number results for a family of vertical-wheel bioreactors.