Inhibition of NO2, PGE2, TNF-α, and iNOS EXpression by Shorea robusta L.: An Ethnomedicine Used for Anti-Inflammatory and Analgesic Activity

This paper is an attempt to evaluate the anti-inflammatory and analgesic activities and the possible mechanism of action of tender leaf extracts of Shorea robusta, traditionally used in ailments related to inflammation. The acetic-acid-induced writhing and tail flick tests were carried out for analgesic activity, while the anti-inflammatory activity was evaluated in carrageenan-and dextran- induced paw edema and cotton-pellet-induced granuloma model. The acetic-acid-induced vascular permeability, erythrocyte membrane stabilization, release of proinflammatory mediators (nitric oxide and prostaglandin E2), and cytokines (tumor necrosis factor-α, and interleukins-1β and -6) from lipopolysaccharide-stimulated human monocytic cell lines were assessed to understand the mechanism of action. The results revealed that both aqueous and methanol extract (400 mg/kg) caused significant reduction of writhing and tail flick, paw edema, granuloma tissue formation (P < 0.01), vascular permeability, and membrane stabilization. Interestingly, the aqueous extract at 40 μg/mL significantly inhibited the production of NO and release of PGE2, TNF-α, IL-1β, and IL-6. Chemically the extract contains flavonoids and triterpenes and toxicity study showed that the extract is safe. Thus, our study validated the scientific rationale of ethnomedicinal use of S. robusta and unveils its mechanism of action. However, chronic toxicological studies with active constituents are needed before its use

Anomalous Price Behaviour around Open Market Stock Repurchase Announcements in India

Executive Summary This article examines the impact of open market share repurchase announcements on stock returns in the Bombay Stock Exchange (BSE). The main objective is to examine whether share repurchase announcements under the open market route have any significant impact on the returns of the stocks traded in the BSE. The article covers the period from 2009 to 2013. For sample selection, two criteria were used: first, the firm should have been listed in the BSE for at least 28 trading days before the repurchase announcement date, and second, the firm should have all relevant data required by this study. A total of 95 repurchase announcements fulfilled these criteria. The analysis period extended from –28 to +28 trading days relative to the repurchase announcement date ( t = 0). The findings of the study will help us to understand how the market responds to share repurchase announcements in India and whether a firm actually benefits by repurchasing its own shares from the market. This study uses a standard event methodology based on an ordinary least squares market model with the aim of finding out whether repurchase announcements generate any abnormal return around the repurchase announcement date. While applying the market model for estimating the abnormal returns, the regression is estimated based on the stock return of the firm and market return of the previous 120 trading days. So, here the estimation window takes into account 120 observations. Using this, the expected returns are generated and then the abnormal returns are derived for the event window, 28 days prior to the event date and 28 days after the event date. The findings of the study indicate that share repurchase announcements do not necessarily generate abnormal stock returns in the Indian equity market unlike developed economies like the US, Canada, and Australia. The whole sample is further divided into various subsamples on the basis of firm size and size of repurchase. The subsample analyses reveal that smaller firms do not necessarily experience higher abnormal stock returns following repurchase announcements than that of the larger firms. The findings weakly support the view that larger repurchase size generates greater abnormal stock returns than the smaller ones

Understanding the temperature- and pressure-dependent electronic properties of FeSi: DFT + DMFT study

Electronic structures of FeSi and Fe1.02Si0.98 under pressure (achieved through volume compression) have been investigated by using DFT+DMFT and KKR-CPA methods, respectively. The widening of band gap with increasing pressure suggests that the experimentally observed insulator-to-metal transition temperature should shift towards the higher temperature for FeSi. KKR-CPA calculations have shown the presence of impurity states in the gapped region which predicts the half-metallic nature. The closure of the gap (in one spin channel) with pressure increment appears to be responsible for the experimentally observed semiconductor-to-metal transition in Fe excess samples at a temperature below 50 K. Magnetic moments at Fe excess sites are found to be decreasing with increasing pressure from $2.4\ \mu_{B}$ per Fe atom ($612\ \text{bohr}^3$ ) to $1.2\ \mu_{B}$ per Fe atom ($507\ \text{bohr}^3$ ). Moreover, for FeSi the calculated local spin susceptibility has shown decreasing behavior with pressure rise similar to experimental result

Electronic correlation effect on nontrivial topological fermions in CoSi

The present study has been carried out to understand the effect of electronic correlations on the recently found fermions in CoSi. For which the spectral functions of bulk and (001) surface of CoSi have been investigated using DFT + DMFT advanced methodology at T = 100 K with and without inclusion of spin–orbit coupling (SOC). The Co $${d_{xz}}$$ + $${d_{yz}}$$ and $$d_{z^2}$$ bands seem to contribute at threefold degenerate $$\Gamma$$ point. On the other hand, fourfold degenerate R point seems to posses maximum of Co $$d_{x^2-y^2} + d_{xy}$$ orbitals and minimum of $$d_{xz} + d_{yz}$$ orbitals. However, SOC and electronic correlations appear to modify the nature of bands involved at $$\Gamma$$ point. DFT + DMFT calculations for the bulk states have shown one extra hole pocket at M point. Incoherent features seem to be possessed by mostly Co $$d_{xz} + d_{yz}$$ orbitals in the spectra of bulk CoSi. The existence of both coherent and incoherent features indicates the presence of quasiparticle–quasiparticle (QP–QP) interactions which is eventually affecting the lifetime ($$\tau$$) of exotic fermionic QPs. For instance, the calculated $$\tau$$ for QPs at $$\omega \sim$$ − 3 and − 186 mev are found to be $$\sim 10^{-9}$$ s and $$\sim 10^{-12}$$ s, respectively, when SOC is not considered. However, $$G_0W_0$$ corrections have shown $$\tau$$ for spin-1 fermionic QP at $$\Gamma$$ to be infinite while for double Weyl fermionic QP at R point to be $$\sim 10^{-12}$$ s. Their effective masses ($$m^*$$) have also been calculated as $$\sim$$ 1.60 and 1.64 at $$\Gamma$$ and R points, respectively. Furthermore, the spectral functions at T = 100 K of (001) surface have also shown both coherent and incoherent features. Consequently, at $$\omega$$ = 0 for surface states, $$\tau$$ has been calculated of the order $$\sim 10^{-8}$$ s for both without SOC and with SOC inclusions

Studying the occupied and unoccupied electronic structure of LaCoO

In this work, we present a systematic study of the occupied and unoccupied electronic states of LaCoO3 compound using DFT, DFT+U and DFT+embedded DMFT methods. The value of U used here is evaluated by using constrained DFT method and found to be ~6.9 eV. It is found that DFT result has limitations with energy positions of PDOS peaks due to its inability of creating a hard gap although the DOS distribution appears to be fine with experimental attributes. The calculated value of U is not an appropriate value for carrying out DFT+U calculations as it has created an insulating gap of ~1.8 eV with limitations in redistribution of DOS which is inconsistent with experimental spectral behavior for the occupied states mainly. However, this value of U is found to be an appropriate one for DFT+embedded DMFT method which creates a gap of ~1.1 eV. The calculated PDOS of Co 3d, La 5d, La 4f and O 2p states are giving a remarkably good explanation for the occupied and unoccupied states of the experimental spectra in the energy range ~–9.0 eV to ~12.0 eV

Extended studies on surface-treated graphite vis-a-vis its application in high alumina refractory castable

This investigation entails our continued research on calcium aluminate coated graphite for application in alumina-carbon monolithic refractories. Surface treatment of graphite flakes by a scalable sol-gel route has been utilized to develop stable bonds between ceramic phases with the functionalized graphite sheets. This study has been primarily conducted to differentiate between the coating evolution pattern at green and calcined conditions. In this regard, C-H-N analysis, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), x-ray diffraction (XRD) with Rietveld analysis, Fourier transformed infrared spectroscopy (FTIR) and zeta potential studies of three kinds of graphites had been compared and critically estimated. These results were supplemented with thermogravimetry (TG), pore size distribution, oxidation resistance and scanning electron microscopy (SEM) of selected samples. A schematic outline of the work has also been proposed. An appreciable improvement of bulk density, apparent porosity and crushing strength of the respective castable has been correlated with the compatibility of the coating to the reactive matrix constituents of the refractory in wide temperature region (110-1500 degrees C)