Measurement of the topological surface state optical conductance in bulk-insulating Sn-doped Bi1.1_{1.1}Sb0.9_{0.9}Te2_2S single crystals

Topological surface states have been extensively observed via optics in thin films of topological insulators. However, in typical thick single crystals of these materials, bulk states are dominant and it is difficult for optics to verify the existence of topological surface states definitively. In this work, we studied the charge dynamics of the newly formulated bulk-insulating Sn-doped Bi$_{1.1}$Sb$_{0.9}$Te$_2$S crystal by using time-domain terahertz spectroscopy. This compound shows much better insulating behavior than any other bulk-insulating topological insulators reported previously. The transmission can be enhanced an amount which is 5$\%$ of the zero-field transmission by applying magnetic field to 7 T, an effect which we believe is due to the suppression of topological surface states. This suppression is essentially independent of the thicknesses of the samples, showing the two-dimensional nature of the transport. The suppression of surface states in field allows us to use the crystal slab itself as a reference sample to extract the surface conductance, mobility, charge density and scattering rate. Our measurements set the stage for the investigation of phenomena out of the semi-classical regime, such as the topological magneto-electric effect.Comment: 5 pages, 3 figures, submitted in Augus

Superconductivity with high upper critical field in Ta-Hf Alloys

High upper-critical field superconducting alloys are required for superconducting device applications. In this study, we extensively characterized the structure and superconducting properties of alloys Ta$_{x}$ Hf$_{1-x}$ (x = 0.2, 0.4, 0.5, 0.6 and 0.8). The substitution of Hf (T$_{C}$ = 0.12 K, type-I superconductor) with Ta (T$_{C}$ = 4.4 K, type-I superconductor) shows an anomalous enhancement of T$_{C}$ with variation of composition. Interestingly, all compositions exhibited strongly coupled bulk type-II superconductivity with a high upper critical field. In particular, for compositions x = 0.2, and 0.4, the upper critical field (H$_{C2}$) approached the Pauli limiting field.Comment: 8 pages, 6 figure

Recovery of Molybdenum from Spent HDs Catalyst Leach Liquor by Solvent Extraction using Aliquat 336

Recycling spent catalysts is very important due to its generation in large amount, enormous economic values and environmental concerns if disposed off directly. This work describes the recovery of Mo from spent hydro-desulph-urization (HDS) catalysts (NiMo/A1204). Catalyst was roa-sted at 500°C to eliminate volatile impurities and leached. The leach solution was subjected to solvent extra-ction to recover Molybdenum. Several solvents such as D2EHPA-TBP, LIX 84-IC and Aliquot 336 were tried and aliquat was finally used for further studies. Conditions for maximum extraction of Mo were optimized by varying different parameters such as pH of the feed solution, sol-vent concentration, aqueous / organic phase ratio etc. Under optimized condition the stage requirement for complete extraction of molybdenum was determined and with 1:2 phase ratio, more than 98% extraction of molybdenum was achieved at pH of 1.5. The molybdenum from loaded organic was stripped with 0.4MNaOH

Scattering of elastic waves by periodic arrays of spherical bodies

We develop a formalism for the calculation of the frequency band structure of a phononic crystal consisting of non-overlapping elastic spheres, characterized by Lam\'e coefficients which may be complex and frequency dependent, arranged periodically in a host medium with different mass density and Lam\'e coefficients. We view the crystal as a sequence of planes of spheres, parallel to and having the two dimensional periodicity of a given crystallographic plane, and obtain the complex band structure of the infinite crystal associated with this plane. The method allows one to calculate, also, the transmission, reflection, and absorption coefficients for an elastic wave (longitudinal or transverse) incident, at any angle, on a slab of the crystal of finite thickness. We demonstrate the efficiency of the method by applying it to a specific example.Comment: 19 pages, 5 figures, Phys. Rev. B (in press

Residual effect of nitrogen levels and weed control methods on growth, yield and economics of wheat grown after rice

A field experiment was laid out in split plot design on residual effect of treatments comprising three nitrogen levels viz. N75 (N1), N100 (N2) and N125 (N3) in main-plot treatments and seven weed control treatments viz. (W1-butachlor + 1 Hand Weeding, W2-butachlor + 2 Mechanical Weeding, W3-butachlor + 2,4-D, W4-bispyribac sodium, W5-butachlor + bispyribac sodium, W6-HW-2, W7- control) as sub-plot treatments conducted during 2015-16 and 2016-17 at the Rajaula Agriculture Farm, MGCGVV, Satna (M.P.) to study the residual effect of N-levels and weed control methods on growth, yield and economics of wheat grown after rice. In case of succeeding wheat, the residual 125 kg N/ha performed the best with respect to growth, yield-attributes with the result 31.11 q/ha grain yield and Rs.33509/ha income. While, under sub plot treatments, Hand weedings two times were recorded significant grain yield (28.66 q/ha) and straw yield (38.17 q/ha) at (P <0.05) over control. However it was found non-significant different and also noticed higher over rest treatments. In this succession, Butachlor + 2, 4-D (0.80 kg/ha) was higher but in second position and similar trend was observed in successive way with rest of treatments

Genome wide expression analysis of CBS domain containing proteins in Arabidopsis thaliana (L.) Heynh and Oryza sativa L. reveals their developmental and stress regulation

<p>Abstract</p> <p>Background</p> <p>In <it>Arabidopsis thaliana </it>(L.) Heynh and <it>Oryza sativa </it>L., a large number of genes encode proteins of unknown functions, whose characterization still remains one of the major challenges. With an aim to characterize these unknown proteins having defined features (PDFs) in plants, we have chosen to work on proteins having a cystathionine β-synthase (CBS) domain. CBS domain as such has no defined function(s) but plays a regulatory role for many enzymes and thus helps in maintaining the intracellular redox balance. Its function as sensor of cellular energy has also been widely suggested.</p> <p>Results</p> <p>Our analysis has identified 34 CBS domain containing proteins (CDCPs) in <it>Arabidopsis </it>and 59 in <it>Oryza</it>. In most of these proteins, CBS domain coexists with other functional domain(s), which may indicate towards their probable functions. In order to investigate the role(s) of these CDCPs, we have carried out their detailed analysis in whole genomes of <it>Arabidopsis </it>and <it>Oryza</it>, including their classification, nomenclature, sequence analysis, domain analysis, chromosomal locations, phylogenetic relationships and their expression patterns using public databases (MPSS database and microarray data). We have found that the transcript levels of some members of this family are altered in response to various stresses such as salinity, drought, cold, high temperature, UV, wounding and genotoxic stress, in both root and shoot tissues. This data would be helpful in exploring the so far obscure functions of CBS domain and CBS domain-containing proteins in plant stress responses.</p> <p>Conclusion</p> <p>We have identified, classified and suggested the nomenclature of CDCPs in <it>Arabidopsis </it>and <it>Oryza</it>. A comprehensive analysis of expression patterns for CDCPs using the already existing transcriptome profiles and MPSS database reveals that a few CDCPs may have an important role in stress response/tolerance and development in plants, which needs to be validated further through functional genomics.</p