Accelerated degradation in amorphous silicon solar cells by a combination of current injection and light insolation

A new degradation technique for amorphous silicon solar cells comprising of a combination of current injection and insolation has been developed. Compared to the conventional light degradation technique, current-induced degradation which involves forward biased current stress, results in a lower stabilized cell parameters including efficiency. This stabilized efficiency is, however, independent of the amount of current injected. The excess degradation is recovered under light illumination. The stabilized value of the conversion efficiency is within experimental error identical to that observed in long term, illumination only degradation. The method is fast, accurate and reliable. Its reliability has also been tested for single junction solar cells having intrinsic layers of different band gaps, as well.     

Effect of gravure process variables on void area in shrink film

The gravure print quality on shrink film depends on process parameters and is fairly gaged by minimum print defects such as voids. The visibility of these defects is visually disturbing and could result in product rejection. This article investigates the effect of process parameters such as viscosity, speed, hardness, and line screen frequency on ink transfer from recess gravure cells and hence on print voids in an attempt to minimize them. A general full factorial design with the abovementioned four independent variables was analyzed by variance, main, and interaction effects. The results revealed line screen, hardness, and ink viscosity as the most influential factors in minimizing the defect. A regression model was developed to predict void area. The model was validated by conducting an additional 11 runs on the press. The predicted values from the model were in close agreement with the press results. The results showed a commendable decrease in the void area by 65%.     

Measurement of effective permeability of reinforcement mats using sensitivity analysis

A methodology using sensitivity analysis is proposed to measure the effective permeability which includes the interaction of the resin and the reinforcement. Initially, mold‐filling experiments were performed at isothermal conditions on the test specimen and the positions of the flow front were tracked with time using a flow visualization method. Following this, mold‐filling experiments were simulated using a commercial software to obtain the positions of the flow front with time at the process conditions used for experiments. Several iterations were performed using different trial values of the permeability until the experimentally tracked and simulated positions of the flow front with time were matched. Finally, the value of the permeability thus obtained was validated by comparing the positions obtained by performing the experiments at different process conditions with the positions obtained by simulating the experiments. In this study, woven roving and chopped strand mats of E‐class glass fiber and unsaturated polyester resin were used for the experiments. From the results, it was found that the measured permeabilities were consistent with varying process conditions. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Macroporous WO3: Tunable morphology as a function of glycine concentration and its excellent acetone sensing performance

Materials-by-Design symbolizes the development of advanced materials with cost and time -effective experimentation. Here, we show the single and unique strategy of developing macroporous WO₃ with different morphologies (nano to micro) using glycine as structure assisting agent. The developed structures were analyzed with various characterizing tools, and tested for practical application as acetone gas sensor (83.87% for 10?ppm). The morphological correlation with the sensitivity is described.     

Proton exchange membranes by grafting of styrene–acrylic acid onto FEP by preirradiation technique. II. Physicochemical properties of the membrane and its sulfonated derivatives

Poly(tetrafluoroethylene‐co‐haxafluoropropylene) (FEP)‐g‐styrene–acrylic acid and its sulfonated derivative membranes were prepared by graft copolymerization of styrene–acrylic acid onto FEP by using preirradiation of γ‐ray technique followed by sulfonation. The physiochemical properties such as ion exchange capacity, water uptake, ionic resistance of the grafted membranes, and their sulfonated derivatives were studied as a function of degree of grafting. These membranes on sulfonation gave acid base, indicating property. The membranes gave yellow color in acidic medium and purple color in alkali medium. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2318–2325, 2004     

Edible oil nanoemulsion: An organic nanoantibiotic as a potential biomolecule delivery vehicle

Water-insoluble bioactive compounds typically require the formulation of lipophilic, antimicrobial delivery system to enhance their bio accessibility. Edible delivery system, in this contrast, plays an important role in food and medical industry. In the present study, an attempt has been made to increase the bioavailability of a model bioactive compound α-tocopherol as a food supplement through edible (coconut) oil nanoemulsion. A 9.5?mg?mL^?1 of encapsulation capacity was obtained with almost 100% release of the loaded α-tocopherol within 24?h. The nanoemulsions were analyzed for various physical and chemical stability parameters, namely, solvent, ionic concentration, temperature, rotatory motion, and various gastrointestinal pH zones. The prepared nanoemulsions were found stable to these parameters. The synthesized nanoemulsions were also evaluated for their biocompatibility and antimicrobial activity. The result showed reasonable cell viability (biocompatibility) with apposite antimicrobial activity confirming the synthesized nanoemulsion as a potential delivery vehicle. Experimental release data were fitted by combining a diffusion-controlled (Higuchi model) and a kinetic-controlled (first-order kinetics) models. The contribution of kinetic-controlled release was found about 70% and that of diffusion-controlled release was found about 30%. The present study reveals plausible application of edible oil nanoemulsion in food, beverages, and health care industries.     

Numerical Investigation of Flow Patterns and Concentration Profiles in Y‐Mixers

The fluid flow patterns and associated concentration fields in Y‐mixers are investigated using lattice Boltzmann method‐based models. The focus lies on the impact of the mixing angle on the flow and concentration fields, with the mixing angle varying between acute (θ = 10°) and obtuse (θ = 130°) angles. Residence time distributions are determined to study the effect of the angles on the mixing and velocity patterns, in particular, different flow regimes, i.e., stratified laminar, vortex, and engulfment flow. The results from the simulations are validated with literature data and found to be in good agreement. Maximum mixing occurs in the 100° obtuse‐angle Y‐mixer, attributed to the extensive engulfment of flows in the mixing channel.     

Optical properties of the c-axis oriented LiNbO3 thin film

C-axis oriented Lithium Niobate (LiNbO₃) thin films have been deposited onto epitaxially matched (001) sapphire substrate using pulsed laser deposition technique. Structural and optical properties of the thin films have been studied using the X-ray diffraction (XRD) and UV-Visible spectroscopy respectively. Raman spectroscopy has been used to study the optical phonon modes and defects in the c-axis oriented LiNbO₃ thin films. XRD analysis indicates the presence of stress in the as-grown LiNbO₃ thin films and is attributed to the small lattice mismatch between LiNbO₃ and sapphire. Refractive index (n = 2.13 at 640 nm) of the (006) LiNbO₃ thin films was found to be slightly lower from the corresponding bulk value (n = 2.28). Various factors responsible for the deviation in the refractive index of (006) LiNbO₃ thin films from the corresponding bulk value are discussed and the deviation is mainly attributed to the lattice contraction due to the presence of stress in deposited film.