Distorted wurtzite unit cells: Determination of lattice parameters of non-polar a-plane AlGaN and estimation of solid phase Al content

Unlike c-plane nitrides, ``non-polar" nitrides grown in e.g. the a-plane or m-plane orientation encounter anisotropic in-plane strain due to the anisotropy in the lattice and thermal mismatch with the substrate or buffer layer. Such anisotropic strain results in a distortion of the wurtzite unit cell and creates difficulty in accurate determination of lattice parameters and solid phase group-III content (x_solid) in ternary alloys. In this paper we show that the lattice distortion is orthorhombic, and outline a relatively simple procedure for measurement of lattice parameters of non-polar group III-nitrides epilayers from high resolution x-ray diffraction measurements. We derive an approximate expression for x_solid taking into account the anisotropic strain. We illustrate this using data for a-plane AlGaN, where we measure the lattice parameters and estimate the solid phase Al content, and also show that this method is applicable for m-plane structures as well

Anthelmintic activity of extracts of coriandrum sativum linn. In indian earthworm

Coriandrum sativum Linn. (CSL) is popularly known as coriander in India belongs to family Apiaceae. The objective of the present work was to evaluate the in-vitro anthelmintic potency of the ethanolic extract and carbon tetrachloride extract of Coriandrum sativum Linn. plant using Indian earthworms (Pheretima posthumad). The various concentrations (50, 100, and 150 mg/ml) of the ethanolic extract and carbon tetrachloride extract were tested in-vitro for anthelmintic potency by determination of time of paralysis and time of death of worm. Piperazine citrate (15mg/ml) used as standard. The result of present study indicates that the Coriandrum sativum Linn. potentiate to paralyze earthworm and also caused its death after some time. The shortest time of paralysis was observed at higher dose (150 mg/ml) of both ethanolic extract and carbon tetrachloride were found to 28 min and 45 min respectively. The results of the study are comparable to standard Piperazine citrate. The result showed that ethanolic extract of Coriandrum sativum Linn. took less time to cause paralysis of the earthworm than that of carbon tetrachloride extract Coriandrum sativum Linn.. Thus the present study demonstrate that the Coriandrum sativum Linn. as an anthelmintic has been confirm as the ethanolic and carbon tetrachloride extracts of whole plant displayed activity against the earthworm used in study. Key word: CSL, Paralysis, death of earthworm

Magnetic and electric properties of double-perovskites and estimation of their Curie temperatures by ab initio calculations

First principles electronic structure calculations have been carried out on ordered double perovskites Sr_2B'B"O_6 (for B' = Cr or Fe and B" 4d and 5d transition metal elements) with increasing number of valence electrons at the B-sites, and on Ba_2MnReO_6 as well as Ba_2FeMoO_6. The Curie temperatures are estimated ab initio from the electronic structures obtained with the local spin-density functional approximation, full-potential generalized gradient approximation and/or the LDA+U method (U - Hubbard parameter). Frozen spin-spirals are used to model the excited states needed to evaluate the spherical approximation for the Curie temperatures. In cases, where the induced moments on the oxygen was found to be large, the determination of the Curie temperature is improved by additional exchange functions between the oxygen atoms and between oxygen and B' and B" atoms. A pronounced systematics can be found among the experimental and/or calculated Curie temperatures and the total valence electrons of the transition metal elements.Comment: 8 pages, 11 figures. Submitted to the Physical Review

Outdoor performance of a reflective type 3D LCPV system under different climatic conditions

Concentrating sunlight and focusing on smaller solar cells increases the power output per unit solar cell area. In the present study, we highlight the design of a low concentrating photovoltaic (LCPV) system and its performance in different test conditions. The system essentially consists of a reflective type 3.6× cross compound parabolic concentrator (CCPC) designed for an acceptance angle of ± 30°, coupled with square shaped laser grooved buried contact (LGBC) silicon solar cells. A heat exchanger is also integrated with the PV system which extracts the thermal energy rejected by the solar cells whilst maintaining its temperature. Indoor characterization is carried out to evaluate the system performance under standard conditions. Results showed a power ratio of 3.12 and an optical efficiency of 73%. The system is placed under outdoor environment on a south facing roof at Penryn, UK with a fixed angular tilt of 50°. The high angular acceptance of the system allows collection of sunlight over a wider range. Results under different climatic conditions are presented and compared with a non-concentrating system under similar conditions. On an average, the LCPV system was found to collect an average of 2.54 times more solar energy than a system without the concentrator

8-Methoxypsoralen Levels in Blood of Vitiligo Patients and in Skin, Ophthalmic Fluids, and Ocular Tissues of the Guinea Pig

8-Methoxypsoralen (8-MOP) levels in the blood of vitiligo patients were determined through the use of a reverse- phase high-performance liquid chromatographic method. The overall recovery of the internal standards was 85-94%, with the lower detection limit of 8-MOP at 2ng. Peak blood levels as low as 130ng/ml and as high as 3892 ng/ml were obtained in patients at 1-3h following the oral administration of 0.6mg/kg body weight of Oxsoralen capsules (Elder Pharmaceuticals Co.). These results are consistent with the clinical observation that maximum response in phototherapy is obtained at about 2h after oral administration of the drug. Two hours after oral administration of 0.6mg/kg of Oxsoralen, 8-MOP levels in the epidermis, dermis, and whole skin of the guinea pig (inng/g) were: epidermis, 330 ± 20; dermis, 89 ± 16; whole skin, 379 ± 19. Also detected were 8-MOP levels of 441 ± 22ng/ml in aqueous humor, 166 ± 18ng/ml in vitreous gel, 355 ± 15ng/g in lens, and 410 ± 26ng/g in retina. These results point to the fact that the eyes of the patient must be protected from exposure to sunlight after psoralen UV treatment, and that 8-MOP is absorbed in blood unevenly and varies from patient to patient. The fact that only 50-60% of the patients responded to psoralen photochemotherapy for vitiligo may be related to the variation of absorption of the drug in individual patients

Mass Outflow Rate From Accretion Discs around Compact Objects

We compute mass outflow rates from accretion disks around compact objects, such as neutron stars and black holes. These computations are done using combinations of exact transonic inflow and outflow solutions which may or may not form standing shock waves. Assuming that the bulk of the outflow is from the effective boundary layers of these objects, we find that the ratio of the outflow rate and inflow rate varies anywhere from a few percent to even close to a hundred percent (i.e., close to disk evacuation case) depending on the initial parameters of the disk, the degree of compression of matter near the centrifugal barrier, and the polytropic index of the flow. Our result, in general, matches with the outflow rates obtained through a fully time-dependent numerical simulation. In some region of the parameter space when the standing shock does not form, our results indicate that the disk may be evacuated and may produce quiescence states.Comment: 30 Latex pages and 13 figures. crckapb.sty; Published in Class. Quantum Grav. Vol. 16. No. 12. Pg. 387

Isotope thermometery in nuclear multifragmentation

A systematic study of the effect of fragment$-$fragment interaction, quantum statistics, $\gamma$-feeding and collective flow is made in the extraction of the nuclear temperature from the double ratio of the isotopic yields in the statistical model of one-step (Prompt) multifragmentation. Temperature is also extracted from the isotope yield ratios generated in the sequential binary-decay model. Comparison of the thermodynamic temperature with the extracted temperatures for different isotope ratios show some anomaly in both models which is discussed in the context of experimentally measured caloric curves.Comment: uuencoded gzipped file containing 20 pages of text in REVTEX format and 12 figures (Postscript files). Physical Review C (in press