Type-II Superconductivity below 4K in Sn0.4Sb0.6

In this article, we report the occurrence of superconductivity in Sn0.4Sb0.6 single crystal at below 4K. Rietveld refined Powder XRD data confirms the phase purity of as grown crystal, crystallizing in rhombohedral R-3m space group with an elongated (2xc) unit cell in c-direction. Scanning Electron Microscope (SEM) image and EDAX measurement confirm the laminar growth and near to desired stoichiometry ratio. Raman Spectroscopy data shows the vibrational modes of Sn-Sb and Sb-Sb modes at 110 and 135cm-1. ZFC (Zero-Field-Cooled) magnetization measurements done at 10Oe showed sharp superconducting transitions at 4K along with a minor step at 3.5K. On the other hand, Paramagnetic Meissner Effect (PME) is observed in FC measurements. Magnetization vs applied field (M-H) plots at 2, 2.2, 2.5, 2.7, 3, 3.2, 3.5, and 3.7K shows typical Type-II nature of observed superconductivity with lower and upper critical fields (Hc1 and Hc2) at 69.42Oe and 630Oe respectively at 2K. Type-II superconductivity is also confirmed by calculated Ginzburg-Landau Kappa parameter value of 3.55. Characteristics length viz. coherence length and penetration depth are also calculated. Weak granular coupling is observed from R-T plot, in which resistance is not dropping to zero down to 2K.Comment: 21 Pages Text + Fig

Palladium(II)-Schiff base complex immobilized covalently on h-BN: An efficient and recyclable catalyst for aqueous organic transformations

A moisture- and air-stable palladium(II)-Schiff base complex supported on h-BN was simply prepared by using commercially available reagents. This nanomaterial was applied as an excellent and recyclable heterogeneous catalyst for the Suzuki and Heck cross-coupling reactions. And it has been characterized by FT-IR, XRD, SEM, XPS, TG and ICP-AES techniques. High yields, ligand-free, low reaction time, water as solvent, non-toxicity and recyclability of the catalyst are the main merits of these protocols. In addition, a series of pharmacologically relevant products were successfully synthesized using this catalyst. Above all, this work opens up an interesting and attractive avenue for the use of h-BN as an efficient support for heterogeneous catalysts

Single Transverse Spin Asymmetries at Parton Level

Two factorization approaches have been proposed for single transverse spin asymmetries. One is the collinear factorization, another is the transverse-momentum-dependent factorization. They have been previously derived in a formal way by using diagram expansion at hadron level. If the two factorizations hold or can be proven, they should also hold when we replace hadrons with parton states. We examine these two factorizations at parton level with massless partons. It is nontrivial to generate these asymmetries at parton level with massless partons because the asymmetries require helicity-flip and nonzero absorptive parts in scattering amplitudes. By constructing suitable parton states with massless partons we derive the two factorizations for the asymmetry in Drell-Yan processes. It is found from our results that the collinear factorization derived at parton level is not the same as that derived at hadron level. Our results with massless partons confirm those derived with single massive parton state in our previous works.Comment: shortened version to match published versio

Flexible and stackable terahertz metamaterials via silver-nanoparticle inkjet printing

There is presently much interest in tunable, flexible, or reconfigurable metamaterial structures that work in the terahertz frequency range. They can be useful for a range of applications, including spectroscopy, sensing, imaging, and communications. Various methods based on microelectromechanical systems have been used for fabricating terahertz metamaterials, but they typically require high-cost facilities and involve a number of time-consuming and intricate processes. Here, we demonstrate a simple, robust, and cost-effective method for fabricating flexible and stackable multiresonant terahertz metamaterials, using silver nanoparticle inkjet printing. Using this method, we designed and fabricated two arrays of split-ring resonators (SRRs) having different resonant frequencies on separate sheets of paper and then combined the two arrays by stacking. Through terahertz time-domain spectroscopy, we observed resonances at the frequencies expected for the individual SRR arrays as well as at a new frequency due to coupling between the two SRR arrays

Composite-fermion crystallites in quantum dots

The correlations in the ground state of interacting electrons in a two-dimensional quantum dot in a high magnetic field are known to undergo a qualitative change from liquid-like to crystal-like as the total angular momentum becomes large. We show that the composite-fermion theory provides an excellent account of the states in both regimes. The quantum mechanical formation of composite fermions with a large number of attached vortices automatically generates omposite fermion crystallites in finite quantum dots.Comment: 5 pages, 3 figure

Effects of GnRH-a on the ovarian maturation of blue tang fish (Paracanthurus hepatus Linnaeus, 1776)

The effects of gonadotropin-releasing hormone – analogue (GnRH-a) injection on the ovarian maturation and steroid hormone level of blue tang (Paracanthurus hepatus) females were investigated. Pre-matured blue tang females were injected with GnRH-a at dosages of 150, 200 and 250 μg/kg body weight and were then observed for fluctuation of steroid hormone levels, including testosterone (T), estradiol (E2) and 17α,20β-dihydroxy-4-pregnen-3-one (DHP) in plasma and ovary after 2 and 7 days. Plasma T level was not significantly different among the treated groups at sampling times. However, the ovarian T levels in the fish injected with 200 and 250 μg/kg GnRH-a were higher than that of the non-administered GnRH-a and fish injected with 150 μg/kg after two days (P < 0.05). After seven days of the administration, the ovarian T level was lowest in the fish without GnRH-a injection and highest in the fish injected with 250 μg/kg (P < 0.05). The plasma and ovarian E2 levels were higher (P < 0.05) in the fish injected with 200 and 250 μg/kg of GnRH-a than in the control fish after 2 and 7 days of injection. Both the plasma and ovarian DHP levels in GnRH-a injected fish were significantly (P < 0.05) increased after day 2 and was highest in the fish injected with 250 μg/kg (P < 0.05). After 7 days of injection, the plasma and ovarian DHP levels remained higher in the GnRH-a injected fish than in the controlled group (P < 0.05). There was no difference in DHP levels among the GnRH-a-treated groups. The results indicate that the dosage of 200 µg/kg of GnRH-a is appropriate for inducing maturation of the blue tang fish