Hybrid Si microwire and planar solar cells: passivation and characterization

We report an efficient hybrid Si microwire (radial junction) and planar solar cell with a maximum efficiency of 11.0% under AM 1.5G illumination. The maximum efficiency of the hybrid cell is improved from 7.2% to 11.0% by passivating the top surface and p-n junction with thin a-SiN:H and intrinsic poly-Si films, respectively, and is higher than that of planar cells of the identical layers due to increased light absorption and improved charge-carrier collections in both wires and planar components.     

Entropy generation in a micropolar fluid past an inclined channel with velocity slip and heat flux conditions: Variation parameter method

An investigation is carried out on the analysis of entropy on the flow of non-Newtonian fluid, in particular, micropolar fluid past an inclined channel. To enhance the fluid properties, velocity and thermal slip conditions are taken into consideration. At the outset, the novelty of the present investigation lies on the analysis of entropy generation that occurs due to the temperature differences between the media. The governing nonlinear equations are transformed to nonlinear ODE by the use of suitable transformed nondimensional variables. Furthermore, the motivation for the study is the solution of these governing equations using the semi-analytical technique, namely, the variation parameter method. The behavior of the flow phenomena is characterized by the contributing parameters, in particular, the Bejan number, on the entropy are displayed via graphs and tables and elaborated in Section 5. The results reveal that the microrotation profile exhibited its dual character with an augmentation of the inclined angle, and both the coupling parameter and the Reynolds number are favorable in resisting entropy.     

Evaluation of hot corrosion behaviour of HVOF sprayed NiCrAl coating on superalloys at 900 °C

In the present investigation, NiCrAl coating was deposited on Ni- and Fe-based superalloy substrates by using high velocity oxy-fuel (HVOF) process to study the hot corrosion behaviour in molten salt (Na₂SO₄–60% V₂O₅) environment at 900 °C under cyclic conditions. The mass gain measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopic analysis (SEM/EDS) and X-ray mapping techniques were used to analyse the corrosion products. The bare superalloys experienced higher weight gain. The NiCrAl-coated Superni 750 alloy (SN 750) provided a better protection among the coated superalloys investigated. The formation of oxides and spinels of nickel, chromium and aluminum may be contributing better resistance to hot corrosion.     

Improving beef color stability: Practical strategies and underlying mechanisms

This paper overviewed the current literature on strategies to improve beef color and attempted to logically explain the fundamental mechanisms involved. Surface color and its stability are critical traits governing the marketability of fresh beef when sold, whereas internal cooked color is utilized as an indicator for doneness at the point of consumption. A multitude of exogenous and endogenous factors interact with the redox biochemistry of myoglobin in post-mortem skeletal muscles. The scientific principles of these biomolecular interactions are applied by the meat industry as interventions for pre-harvest (i.e. diet, animal management) and post-harvest (i.e. packaging, aging, antioxidants) strategies to improve color stability in fresh and cooked beef. Current research suggests that the effects of several of these strategies are specific to type of animal, feeding regimen, packaging system, and muscle source. Meat scientists should explore novel ways to manipulate these factors using a biosystems approach to achieve improved beef color stability, satisfy consumer perception, and increase market profitability.     

Effects of Growth Temperature on Indium Incorporation in InAlN Alloys Grown by GSMBE on Si(111)

In _x Al_1−x N alloys with low indium content (0.025 < x < 0.080) were grown on Si(111) substrates, with an AlN buffer layer, using gas source molecular beam epitaxy with ammonia under nitrogen-rich conditions. Composition was varied by changing the growth temperature from 580°C to 660°C. Growth temperature in excess of 580°C was found to be necessary to obtain compositional uniformity. As temperature was varied from 590°C to 660°C, both the growth rate and indium incorporation decreased substantially. Rising In content observed near the surface of each sample was attributed to native indium oxide formation.     

Application‐driven analysis of two generations of capability computing: the transition to multicore processors

Multicore processors form the basis of most traditional high performance parallel processing architectures. Early experiences with these computers showed significant performance problems, both with regard to computation and inter‐process communication. The transition from Purple, an IBM POWER5‐based machine, to Cielo, a Cray XE6, as the main capability computing platform for the United States Department of Energy's Advanced Simulation and Computing campaign provides an opportunity to reexamine these issues after experiences with a few generations of multicore‐based machines. Experiences with Purple identified some important characteristics that led to strong performance of complex scientific application programs at very large scales. Herein, we compare the performance of some Advanced Simulation and Computing mission critical applications at capability scale across this transition to multicore processors. Copyright © 2012 John Wiley & Sons, Ltd.     

Computational Investigation of the pH Dependence of Stability of Melanosome Proteins: Implication for Melanosome formation and Disease

Intravesicular pH plays a crucial role in melanosome maturation and function. Melanosomal pH changes during maturation from very acidic in the early stages to neutral in late stages. Neutral pH is critical for providing optimal conditions for the rate-limiting, pH-sensitive melanin-synthesizing enzyme tyrosinase (TYR). This dramatic change in pH is thought to result from the activity of several proteins that control melanosomal pH. Here, we computationally investigated the pH-dependent stability of several melanosomal membrane proteins and compared them to the pH dependence of the stability of TYR. We confirmed that the pH optimum of TYR is neutral, and we also found that proteins that are negative regulators of melanosomal pH are predicted to function optimally at neutral pH. In contrast, positive pH regulators were predicted to have an acidic pH optimum. We propose a competitive mechanism among positive and negative regulators that results in pH equilibrium. Our findings are consistent with previous work that demonstrated a correlation between the pH optima of stability and activity, and they are consistent with the expected activity of positive and negative regulators of melanosomal pH. Furthermore, our data suggest that disease-causing variants impact the pH dependence of melanosomal proteins; this is particularly prominent for the OCA2 protein. In conclusion, melanosomal pH appears to affect the activity of multiple melanosomal proteins.     

Effect of size distribution on mixing of a polydisperse wet granular material in a belt-driven enclosure

We use a recently developed coupled fluid–particle discrete element model to study mixing of a wet granular material in a two dimensional setting. The particles are modeled as linearly elastic disks and are considered to be immersed in a Newtonian fluid. The fluid–particle interaction is modeled using a linear drag model under the assumption that the fluid inertia is small compared to particle inertia. The granular slurry is driven by a belt moving at constant velocity in a square cavity. In the simulations, we consider three types of size distributions: monodisperse, bidisperse with several particle size ratios, and polydisperse Gaussian distributions with several different standard deviations. Mixing is characterized using both strong and weak measures. Size segregation is observed only in the bidisperse simulations. The energy required for mixing polydisperse slurries decreases with increasing standard deviation of the particle sizes. Finally, we show the benefits of engineering certain polydisperse particle size distributions towards minimizing energy consumption.