Micropropagation of White Palash tree (Butea monosperma (Lam.) Taub. Var. lutea (Witt.)).

An efficient and reproducible protocol is established for rapid in vitro multiplication of an endangered, valuable medicinal plant, Butea monosperma (Lam.) Taub. Var. lutea, through cotyledonary nodes of mature seeds. Among various cytokinins tested, high frequency of direct shoot regeneration was induced on Murashige and skoog (MS) medium supplemented with BAP, which found to be more effective and showed optimal response at 2 mg/L with a maximum number of 8.35±0.32 multiple shoots per explant. Proliferation of shoots was established by repeated subculturing on to same regeneration medium with 2-3 weeks of time interval. Rooting of regenerated shoots was achieved after 3 weeks of culture on MS medium containing 1 mg/L IBA. In vitro raised plantlets were transferred to pots containing sterilized soil and vermiculate mixture in 1:1 ratio and then shifted to greenhouse. Well established plantlets exhibited 75% survival rate

Standardization of C<SUP>14</SUP> stock solution and filter efficiency in the comparison of primary productivity measurements

Parallel experiments using natural populations were conducted to find out the variability of values of organic production obtained by two different C14 stock solutions, standardization techniques and counting systems as well as the relative efficiency of three types of filters. The results indicate that a uniform method of standardization of stock solution and a careful selection of filters are necessary more than anything else if values of organic production obtained by different workers are to be compared

Theory of Andreev reflection in a two-orbital model of iron-pnictide superconductors

A recently developed theory for the problem of Andreev reflection between a normal metal (N) and a multiband superconductor (MBS) assumes that the incident wave from the normal metal is coherently transmitted through several bands inside the superconductor. Such splitting of the probability amplitude into several channels is the analogue of a quantum waveguide. Thus, the appropriate matching conditions for the wave function at the N/MBS interface are derived from an extension of quantum waveguide theory. Interference effects between the transmitted waves inside the superconductor manifest themselves in the conductance. We provide results for a FeAs superconductor, in the framework of a recently proposed effective two-band model and two recently proposed gap symmetries: in the sign-reversed s-wave ($\Delta\cos(k_x)\cos(k_y)$) scenario resonant transmission through surface Andreev bound states (ABS) at nonzero energy is found as well as destructive interference effects that produce zeros in the conductance; in the extended s-wave ($\Delta[\cos(k_x)+\cos(k_y)]$) scenario no ABS at finite energy are found.Comment: 4 pages, 5 figure

Bifacial Si heterojunction-perovskite organic-inorganic tandem to produce highly efficient (η T * ~ 33%) solar cell

As single junction photovoltaic (PV) technologies both Si heterojunction (HIT) and perovskite based solar cells promise high efficiencies at low cost. Intuitively a traditional tandem cell design with these cells connected in series is expected to improve the efficiency further. Using a self-consistent numerical modeling of optical and transport characteristics however we find that a traditional series connected tandem design suffers from low JSC due to band-gap mismatch and current matching constraints. Specifically a traditional tandem cell with state-of-the-art HIT ( η=24% ) and perovskite ( η=20% ) sub-cells provides only a modest tandem efficiency of ηT~ 25%. Instead we demonstrate that a bifacial HIT/perovskite tandem design decouples the optoelectronic constraints and provides an innovative path for extraordinary efficiencies. In the bifacial configuration the same state-of-the-art sub-cells achieve a normalized output of η∗T  = 33% exceeding the bifacial HIT performance at practical albedo reflections. Unlike the traditional design this bifacial design is relatively insensitive to perovskite thickness variations which may translate to simpler manufacture and higher yield

Safety evaluation of chromium picolinate in experimental rats

Background: Chromium, an essential trace mineral plays an important role in the metabolism of carbohydrate, fat and proteins. Chromium picolinate (Cr.Pic) is used in alternative medicine to treat chromium deficiency. Though Cr.Pic is increasingly used to treat diabetes and obesity, studies on its safety profile is limited.Methods: Acute toxicity study was conducted by oral administration of Cr.Pic (2000 mg/kg body weight). The animals were maintained another 14 days with once a day observation. For sub-chronic studies, test groups were treated with Cr.Pic 10 mg/kg/day for 90 days. Tests for hepatic and renal function were conducted. Effect of Cr.Pic on behavioural changes and motor co-ordination was done on every week. Histopathological studies were conducted on day 90 at the end of the experiment.Results: Acute toxicity study of Cr.Pic showed no signs of toxicity and mortality. Absence of any behavioural alteration or mortality during the period of 14 days indicates that Cr.Pic has no latent effect. Similar results were obtained with sub-chronic studies suggesting safety of Cr.Pic. Cr.Pic treated groups showed no changes in learning and motor co-ordination compared to the untreated group. No gross histopathological changes were seen in any group indicating safety of Cr.Pic.Conclusions: The present study conferred safety profile of Cr.Pic from normal results obtained in hepatic function, renal function, behavioural and histopathological studies, suggesting its safety

Pairing in the iron arsenides: a functional RG treatment

We study the phase diagram of a microscopic model for the superconducting iron arsenides by means of a functional renormalization group. Our treatment establishes a connection between a strongly simplified two-patch model by Chubukov et al. and a five-band- analysis by Wang et al.. For a wide parameter range, the dominant pairing instability occurs in the extended s-wave channel. The results clearly show the relevance of pair scattering between electron and hole pockets. We also give arguments that the phase transition between the antiferromagnetic phase for the undoped system and the superconducting phase may be first order

Standardization of C14 stock solution and filter efficiency in the comparison of primary productivity measurements

During the intercalibration trials on primary production conducted at the University of Hawaii, Honolulu, in September 1961, in which one of the authors (R. R. P.) also participated, factors influencing the variability of productivity measurements like sampling error, differential toxicity of samplers, sample treatment before incubation, inoculation, incubation, planchet preparation and counting were considered. Of these some of the factors such as sampling error and inoculation were made uniform by each group of scientists sub-sampling one and the same sample and all participants using the same CI4 stock

Investigation of LiFeAs by means of "Break-junction" Technique

In our tunneling investigation using Andreev superconductor - normal metal - superconductor contacts on LiFeAs single crystals we observed two reproducible independent subharmonic gap structures at dynamic conductance characteristics. From these results, we can derive the energy of the large superconducting gap $\Delta_L=(2.5 \div 3.4)$ meV and the small gap $\Delta_L=(0.9 \div 1)$ meV at $T = 4.2$ K for the $T_C^{local} \approx (10.5 \div 14)$ K (the contact area critical temperature which deviation causes the variation of $\Delta_L$). The BCS-ratio is found to be $2\Delta_L/k_BT_C = (4.6 \div 5.6)$, whereas $2\Delta_S/k_BT_C \ll 3.52$ results from induced superconductivity in the bands with the small gap.Comment: 7 pages, 5 figures. Published in Pis'ma v ZhETF 95, 604-610 (2012