Light Trapping Textures Designed by Electromagnetic Optimization for Sub-Wavelength Thick Solar Cells

Light trapping in solar cells allows for increased current and voltage, as well as reduced materials cost. It is known that in geometrical optics, a maximum 4n^2 absorption enhancement factor can be achieved by randomly texturing the surface of the solar cell, where n is the material refractive index. This ray-optics absorption enhancement limit only holds when the thickness of the solar cell is much greater than the optical wavelength. In sub-wavelength thin films, the fundamental questions remain unanswered: (1) what is the sub-wavelength absorption enhancement limit and (2) what surface texture realizes this optimal absorption enhancement? We turn to computational electromagnetic optimization in order to design nanoscale textures for light trapping in sub-wavelength thin films. For high-index thin films, in the weakly absorbing limit, our optimized surface textures yield an angle- and frequency-averaged enhancement factor ~39. They perform roughly 30% better than randomly textured structures, but they fall short of the ray optics enhancement limit of 4n^2 ~ 50

Antifungal properties of extracts of Ocimum tenuiflorum and Datura stramonium against some vegetable pathogenic fungi

A study was carried out to evaluate the antifungal properties of Ocimum tenuiflorum (also known as Ocimum sanctum) and Datura stramonium extracts on Fusarium oxysporum and Rhizopus stolonifer using the well in agar method. The in vitro studies have been performed by using leaf, stem bark and root bark chloroform, alcoholic and aqueous extracts. All extracts showed antifungal activity. The stem bark alcoholic extract of D. stramonium showed maximum activity; while minimum activity was observed with root aqueous extract of O. tenuiflorum against the fungi under investigation. Results showed that radial growth in all the test organisms was impaired by the addition of the extracts in the culture medium used. The test organisms differed in their reaction to the different extracts but on the whole, growth inhibition increased with the concentration of each extract. The antifungal activity for both the plants and for both the organisms was found is in increasing order i.e. root bark < leaves < stem bark

NON-LINEAR REGRESSION ANALYSIS IN UPFLOW ANAEROBIC SLUDGE BLANKET REACTOR

A dimensionless approach was used to model the granule size variation in upflow anaerobic sludge blanket (UASB) reactor under different operating condition like organic loading rate, operating time, gas production rate, volatile suspended solids, suspended solids, upflow velocity, polymer loading, sludge volume index and effluent COD concentrations. Present study examines mathematically the effect of introducing polymers to enhance the granule size development in a UASB reactor especially in treatment of low strength wastewater in UASB reactor. The experimental results of investigators on different operating conditions were collected and subjected to dimensionless and non-linear regression analysis to model the enhancement of granule size in UASB reactor. The results using the dimensionless approach and the non linear regression show that better prediction of granule size variations for the data set based on the statistical estimates, errors and a satisfactory coefficient of determination (R2-values). The dimensionless approach of the present study can be successfully used to predict the granule size variations in UASB reactor

A quantitative framework for estimating water resources in India

While issues related to water attract considerable attention in all spheres of life in India, very little quantitative information is available on the water budget of the country. There are primarily two reasons for this lacuna: first, the dearth of information on the variables associated with hydrology, and second, the absence of an easily accessible quantitative framework to put these variables in perspective. In this article, we discuss a framework that has been assembled to address both these issues. At the core of the framework is a hydrological routing model (HYDRA) that has been used to study the water balance of basins on various scales, ranging from a few square kilometres to continents. The basic data needed for implementing the framework are a suitable digital elevation model (DEM) and data on precipitation and evapotranspiration. Available discharge data can be used to validate the performance of the model. We demonstrate the viability of the framework by applying it to the hydrology of the Mandovi river on the western slopes of the Sahyadris; it is typical of the rivers along the Indian west coast. Most of the catchment area of the river is in Goa, but parts of the river also flow through Karnataka and Maharashtra. We use a 30" -resolution (∼ 1 km) DEM (GLOBE) and HYDRA to show that the model output mimics the observed discharge well, providing indirect validation for the surface run-off and sub-surface drainage values on which no data are available

First-order melting of a weak spin-orbit Mott insulator into a correlated metal

The electronic phase diagram of the weak spin-orbit Mott insulator (Sr(1-x)Lax)3Ir2O7 is determined via an exhaustive experimental study. Upon doping electrons via La substitution, an immediate collapse in resistivity occurs along with a narrow regime of nanoscale phase separation comprised of antiferromagnetic, insulating regions and paramagnetic, metallic puddles persisting until x~0.04. Continued electron doping results in an abrupt, first-order phase boundary where the Neel state is suppressed and a homogenous, correlated, metallic state appears with an enhanced spin susceptibility and local moments. As the metallic state is stabilized, a weak structural distortion develops and suggests a competing instability with the parent spin-orbit Mott state.Comment: 5 pages, 4 figure

Heavy landings of juveniles of Indian scad, Decapterus russelli at Munambam Fisheries Harbour

Among the carangid fishes, the Indian scad, Decapterus russelli is an important pelagic fish and a major commercial species contributing to the marine fisheries of Kerala. The fish is locally called “kozhuchala” and it forms a regular fishery. The species is often caught as by-catch in shrimp trawl nets having cod-end mesh sizes ranging from 15 mm to 20 mm that is operated in the depth range of 55- 90 m almost throughout the year. They are consumed fresh as well as sun dried form

[n]peristylanes and [n]oxa[n]peristylanes (n=3-6): a theoretical study

Theoretical studies at the HF and Becke3LYP levels using 6-31G&#8727; basis sets were carried out on a series of [n]peristylanes and [n]oxa[n]peristylanes (n = 3-6) to understand their structure and energetics. The structures of the [3]- and [4]peristylanes (1, 2) and their oxa-derivatives (5, 6) were calculated to have the anticipated high symmetry, Cnv. In contrast, a Cs structure (9) at HF/6-31G&#8727; and another (25) at the Becke3LYP/6-31G&#8727; level were calculated for the [5]oxa[5]peristylane. The energy difference between them is extremely small even though there are major differences in the structures indicating a very soft potential energy surface. On the other hand, the potential energy surface of [6]oxa[6]peristylane is not as soft. Similar structures were also calculated for the top rings. Calculations on the seco-compounds 11-14 and 15-19 (Table 4) indicate that there is no unusual strain involved in the formation of 27 from 19. The Li+ interaction energies of the [n]oxa[n]peristylanes are 61.7 (n = 3), 72.8 (n = 4), 84.2 (n = 5) and 91.7 (n = 6) kcal mol-1 at the Becke3LYP/6-31G&#8727; level. Dramatic differences between the C-C bond lengths obtained from the solid state X-ray diffraction studies and those from the calculations for the [n]oxa[n]peristylanes were also observed