Pressure induced electronic topological transition in Sb2S3

Pressure induced electronic topological transitions in the wide band gap semiconductor Sb2S3 (Eg = 1.7-1.8 eV) with similar crystal symmetry (SG: Pnma) to its illustrious analog, Sb2Se3, has been studied using Raman spectroscopy, resistivity and the available literature on the x-ray diffraction studies. In this report, the vibrational and the transport properties of Sb2S3 have been studied up to 22 GPa and 11 GPa, respectively. We observed the softening of phonon modes Ag(2), Ag(3) and B2g and a sharp anomaly in their line widths at 4 GPa. The resistivity studies also shows an anomaly around this pressure. The changes in resistivity as well as Raman line widths can be ascribed to the changes in the topology of the Fermi surface which induces the electron-phonon and the strong phonon-phonon coupling, indicating a clear evidence of the electronic topological transition (ETT) in Sb2S3. The pressure dependence of a/c ratio plot obtained from the literature showed a minimum at ~ 5 GPa, which is consistent with our high pressure Raman and resistivity results. Finally, we give the plausible reasons for the non-existence of a non-trivial topological state in Sb2S3 at high pressures.Comment: 24 pages, 6 Figures, 2 tables submitted for publicatio

An expert system for LD steel making

LD process of steelmaking accounts for 70% of steel production throughout the world. Due to various constraints like the complexity of LD process; variation in quantity, quality and grade of input materials; varying operating conditions, random parameters and their values; the interventions of an expert and skilled operator is necessary to tackle the complex situation. To overcome this, there exists, a need of a system, which does not only possess the process control capabilities, but also emulates operator's expertise in terms of his knowledge and skill. Such a system has been developed named "Expert Steelmaker". The paper discusses the "Expert Steelmaker" which can presently be used in an advisory mode by the LD steelmaking operator

Functional PET Evaluation of the Photosensitive Baboon

The baboon provides a unique, natural model of epilepsy in nonhuman primates. Additionally, photosensitivity of the epileptic baboon provides an important window into the mechanism of human idiopathic generalized epilepsies. In order to better understand the networks underlying this model, our group utilized functional positron emission tomography (PET) to compare cerebral blood flow (CBF) changes occurring during intermittent light stimulation (ILS) and rest between baboons photosensitive, epileptic (PS) and asymptomatic, control (CTL) animals. Our studies utilized subtraction and covariance analyses to evaluate CBF changes occurring during ILS across activation and resting states, but also evaluated CBF correlations with ketamine doses and interictal epileptic discharge (IED) rate during the resting state. Furthermore, our group also assessed the CBF responses related to variation of ILS in PS and CTL animals. CBF changes in the subtraction and covariance analyses reveal the physiological response and visual connectivity in CTL animals and pathophysiological networks underlying responses associated with the activation of ictal and interictal epileptic discharges in PS animals. The correlation with ketamine dose is essential to understanding differences in CBF responses between both groups, and correlations with IED rate provides an insight into an epileptic network independent of visual activation. Finally, the ILS frequency dependent changes can help develop a framework to study not only spatial connectivity but also the temporal sequence of regional activations and deactivations related to ILS. The maps generated by the CBF analyses will be used to target specific nodes in the epileptic network for electrophysiological evaluation using intracranial electrodes

A low-cost Raman spectrometer design used to study Raman scattering from a single-walled carbon nanotube

The paper discusses the design of a low cost Raman spectrometer. Singlewalled Nanotubes (SWNT) have been studied to demonstrate the reach of such a system. We observe both the Radial-breathing Mode (RBM) and the tangential mode from the SWNT. The tube diameters of the SWNT used in these experiments have been determined using RBM to be predominantly 1.4 and 1.6 nm. These are consistent with the TEM images taken of the same sample. The new method of producing SWNT using Ni-Y catalyst in electric-arc discharge method produces nanotubes with very small dispersion in diameter and high yields. The chirality of the SWNT can be deduced from their radial breathing modes and it suggests that they are metallic in nature

Effect of Packaging and Storage Temperature on Shelf-Life of Minimally Processed Onion (Allium cepa L.)

Minimally processed onion is a ready-to-use onion product offering the consumer a fully usable commodity, without much change to freshness of the produce. Effect of packaging and storage temperature on shelf-life in minimally processed onion was studied. Packaging and temperature play an important role in determining shelf-life in minimally processed onion. Onion pieces approx. 8-10mm thick were cut with a plain, sharp knife and subjected to dip-treatment with the firming agent, calcium lactate (2%), for 5 minutes. The samples were surface-dried and packaged in polypropylene bags of size 250 X 125mm, of variable thicknesses (25, 50 or 75μm) and stored at low temperatures and high RH:8±1°C and 83±2% RH; 10±1°C and 82±2% RH; and, 12±1°C and 80±2% RH. It was found that onion cv. Arka Sona sliced with a plain, sharp knife, pre-treated with 2% calcium lactate, surface-dried and packaged in polypropylene bags sized 250X125mm (50μm thick), and stored at 8+1°C and 83±2% RH retained freshness and nutritive value, were microbially safe and acceptable, with a shelf-life of 14 days at storage

(E)-3-(Biphenyl-4-yl)-1-(3-bromo­phen­yl)prop-2-en-1-one

In the title compound, C21H15BrO, there are two planar rings connected through a conjugated double bond. As it crystallizes in a non-centrosymmetric space group it can be regarded as a good candidate for non-linear optical applications. The mol­ecule adopts an E configuration and the C—C=C—C torsion angle is 177.1 (4)°. The overall conformation of the compound may be described by the values of dihedral angles between the approximately planar parts. The terminal rings are twisted by an angle of 51.52 (9)°, while the biphenyl part is almost planar, the dihedral angle between the planes of the rings being 4.44 (17)°. The unit cell has one long dimension, above 35 Å, characteristic also of a majority of related compounds. The mol­ecules pack head-to-tail along this direction. C—H⋯π inter­actions are observed in the crystal structure

2-(4-Chloro­phen­oxy)acetohydrazide

In the title compound, C8H9ClN2O2, the two planar fragments, i.e. the chloro­phenyl and C—C(=O)—N groups, are inclined at 14.93 (17)°. In the crystal, relatively weak inter­molecular N—H⋯N, C—H⋯O and N—H⋯O hydrogen bonds connect the mol­ecules into layers. The hydro­phobic parts of mol­ecules stick outside these layers and are connected with the neighbouring layers only by van der Waals contacts and Cl⋯Cl inter­actions [3.406 (2) Å]