High Field Magneto-Conductivity Analysis of Bi2Se3 Single Crystal

We report the high field (up to 14Tesla) magneto-conductivity analysis of Bi2Se3 topological insulator grown via the self flux method. The detailed experimental investigations including crystal growth as well as the electrical, thermal and spectroscopic characterizations of the resultant Bi2Se3 single crystal are already reported by some of us. The current letter deals with high field magneto-conductivity analysis in terms of Hikami Larkin Nagaoka (HLN) model, which revealed that the electronic conduction is dominated by both surface states driven weak anti localization (WAL), as well the bulk WL (weak localization) states. Further, by applying the HLN equation we have extracted the fitting parameters i.e., phase coherence length and the pre-factor. The HLN equation exhibited values of [pre factor close to -1.0, indicating both WAL and WL contributions. On the other hand, the extracted phase coherence length is seen to decrease from 11.125 nm to 5.576 nm as the temperature is increased from 5K to 200K respectively. Summarily, the short letter discusses primarily the temperature dependent magneto-conductivity analysis of pristine Bi2Se3 single crystal by the HLN model.Comment: Letter to Editor MS: 10 pages including 3 Fig

Crystal Growth and Characterization of Bulk Sb2Te3Topological Insulator

The Sb2Te3 crystals are grown using the conventional self flux method via solid state reaction route, by melting constituent elements (Sb and Te) at high temperature (850 C), followed by slow cooling (2 C per hour).The weak anti localization (WAL) related low field (2 Tesla) magneto-conductance at low temperatures (2.5 K and 20 K) has been analysed and discussed using the Hikami- Larkin - Nagaoka (HLN) model. Summarily, the short letter reports an easy and versatile method for crystal growth of bulk Sb2Te3 topological insulator (TI) and its brief physical property characterization.Comment: 18 Pages Text + Figs: Accepted Mat. Res. Exp. (May 2018

5-Exo-dig, 5-exo-trig cascade radical cyclisation on sugar-furanose templates: entry to angularly fused oxa-and dioxa-triquinane skeletons

Serial radical cyclisation on sugar-furanose templates to create angularly fused oxa- and dioxa-triquinane skeletons has been described, the salient feature of this approach being to incipiently generate a tertiary radical from cyclopropylmethyl bromide with simultaneous release of allyl group and to subsequently incorporate it in the triquinane system

Two-fold anisotropic superconducting state in topological superconductor Sn4_4Au

Here we report the anisotropic magnetotransport properties in the superconducting state of Sn$_4$Au single crystal. Sn$_4$Au single crystal is synthesized through an easy melt growth method. Superconducting properties are evidenced by resistivity vs. temperature and DC magnetization measurements. Isothermal magnetization measurements hint toward type-II superconductivity in Sn$_4$Au. In-plane and out-of-plane resistivity measurements show anisotropic behavior of the upper critical field at temperatures below superconducting transition (T$_c$ = 2.3 K). The observed anisotropy is more elucidated in resistivity measurements performed below Tc at different tilt angles. The anisotropy parameter is found to be 1.26. The observed results show the presence two-fold anisotropic superconducting state in Sn$_4$Au single crystal, which may be induced due to the layered structure of synthesized Sn$_4$Au single crystal.Comment: 10 Pages Text + Figs: Revised Submitted: Euro. Phys. Let

Hikami-Larkin-Nagaoka (HLN) treatment of the Magneto Conductivity of Bi2Te3 Topological Insulator

We report the magneto-conductivity analysis at different temperatures under magnetic field of up to 5Tesla of a well characterized Bi2Te3 crystal. Details of crystal growth and various physical properties including high linear magneto resistance are already reported by some of us. To elaborate upon the transport properties of Bi2Te3 crystal, the magneto conductivity is fitted to the known HLN (Hikami Larkin Nagaoka) equation and it is found that the conduction mechanism is dominated by both surface driven WAL (weak anti localization) and the bulk WL states. The value of HLN equation coefficient signifying the type of localization (WL, WAL or both WL and WAL) falls within the range of -0.5 to -1.5. In our case, the low field (0.25Tesla) fitting of studied crystal exhibited value close to -0.86 for studied temperatures of up to 50K, indicating both WAL and WL contributions. The phase coherence length is found to decrease from 98.266 to 40.314nm with increasing temperature. Summarily, the short letter reports the fact that bulk Bi2Te3 follows the HLN equation and quantitative analysis of the same facilitates to know the quality of studied crystal in terms of WAL to WL contributions and thus the surface to bulk conduction ratio.Comment: Short Letter MS 10 pages including 3 Figs: Letter J. Sup. & Novel Mag. (2018

Characterization of nutraceuticals in bael powder prepared from fruits harvested at different developmental stages

Bael [Aegle marmelos (L.) Correa], is well known in Indian traditional medical system for its multipurpose use in treatment of various diseases. Fresh ripe fruits are used in various types of shakes and sharbats but bael fruits are mainly used into its processed form like nectar or squash, jelly, candy and murabba. Bael powder is another form of product which has very high pharmaceutical value, long storability and is the pure concentrated form of fruit pulp. The aim of this study is to measure the nutraceutical values in bael powder (dry weight basis) prepared from fruit of CISH B-1 harvested at various stages of growth and development [180–335 days after fruit set (DAFS)] by using a simple HPLC technique and atomic absorption spectrophotometer (AAS). The antioxidants value (in terms of FRAP) ranges from 13.45 mmol/g at 180 DAFS (month of November) to 22.6 mmol/g at 335 DAFS (month of April). Maximum polyphenols content (5.99%) was observed at 305 and 335 DAFS (months of March and April). The antioxidants and polyphenols were enhanced significantly with the maturity of the fruits. Marmelosin and psoralen concentrations were highest at 215 DAFS and were found as 737 and 511 µg/g, respectively. Thereafter, both compounds declined significantly in mature fruit powder. Mineral contents in powder also varied with maturity stages. From this study, it may be concluded that powder prepared from immature fruits collected at early stages of development (November-January; 180–245 DAFS), possessed significantly higher amount of potassium, iron, marmelosin, psoralen and tannic acid, whereas, mature fruit powder (harvested during March-April; 305-335 DAFS) contains significantly higher content of zinc, copper, polyphenols and antioxidant

Classification of singular Q-homology planes. I. Structure and singularities

A Q-homology plane is a normal complex algebraic surface having trivial rational homology. We obtain a structure theorem for Q-homology planes with smooth locus of non-general type. We show that if a Q-homology plane contains a non-quotient singularity then it is a quotient of an affine cone over a projective curve by an action of a finite group respecting the set of lines through the vertex. In particular, it is contractible, has negative Kodaira dimension and only one singular point. We describe minimal normal completions of such planes.Comment: improved results from Ph.D. thesis (University of Warsaw, 2009), 25 pages, to appear in Israel J. Mat