Study of the long-term evolution of the accretion dynamics of GX 339-4

We study the dynamical behaviour of the galactic black hole source GX 339-4 during 2002-2011 outbursts using RXTE, Swift(XRT), XMM-Newton(PN) archival data. We present the spectral evolution of the source using four outbursts data and discuss their similarities/differences between outbursts. We infer that the second peak in 2002/03 and 2004/05 outbursts can be due to a second instant of triggered instability in the accretion disc due to irradiation from the central X-ray source after peak-I. This propagates in viscous time scale and takes ~80-90 days after peak-I to produce peak-II. This unifies all four outbursts having a long rising time of ~90 days. The dynamical evolution of accretion parameters have been studied by modeling the individual observed spectrum with two-component accretion disc model where a Keplerian accretion disc produces the soft photons and the hard part of the spectrum originates from a hot sub-Keplerian central corona. A generic mathematical model has been proposed to understand the evolution of accretion parameters for sources like GX 339-4 which have longer rising time. Also, the possible differences of physical scenario for outbursts with shorter rising time are also discussed.Comment: Accepted for publication in mnra

DIVERSITY AND PHENETIC STUDY ON SYCONIUM OF FICUS L. (MORACEAE) FROM KERALA, INDIA REVEALING NATURAL CLASSIFICATION ALONG WITH AN IDENTIFICATION KEY

NAIR, S. S., BACHAN, K. H. A.  &  EBIN, P. J.  2021. Diversity and phenetic study on syconium of Ficus L. (Moraceae) from Kerala, India revealing natural classification along  with an identification key. Reinwardtia  20(1): 27–36. — Ficus L. commonly called ‘figs’ is one of the most complex genera among the angiosperms with its specialised inflorescence called syconium that looks like a fruit. Syconium of 33 species of  Ficus reported from Kerala were observed here to develop a novel key, solely based on syconium morphology. Numerical taxonomic methodology  for syconium  morphological characters  were standardised, considering 22 characters with 104 character states and analysed using similarity clustering. The floral features of the genus are very much complex and all the existing keys for the species identification relays on both vegetative as well as floral features. Hence, the present key will be practical  in  use  when  syconium  is  the  only  available  part.  The  numerical  analysis  of  the  syconium  features  well clustered and separated the trees with cauliflorous inflorescence, hemi epiphytic -epiphytic life forms and independent trees similar to the natural classification of the figs as  “Atthi, Itthi and Aal”, indicating that phenetic analysis using the syconium  characters  alone  provided  a  grouping  similar  to  the  natural  grouping  based  on  the  habit.  Preliminary phylogenetic analysis of figs also provided a similar clustering. This gives an insight into the fact that the separation of figs into these natural groups is reflecting phylogenetic trait. Detailed studies including more morphological traits and molecular analysis could establish the phylogenetic relation of figs in relation to the evolutionary history of climate and vegetation

Dielectric relaxation studies of acetonitrile/propylene glycol and their binary mixtures

Dielectric relaxation spectra in the frequency range 0.02 < ν/GHz < 20 have been collected for propylene glycol (PG), acetonitrile (AN) and their binary mixtures between 303 K-323 K. The average relaxation times have been calculated by the Cole-Davidson and Cole-Cole relaxation models. The experimental determined values of static dielectric permittivity (ε0), relaxation time (τ), excess permittivity (εE) and excess inverse relaxation time (1/τ)E show smooth temperature dependence. The larger relaxation time values of propylene glycol when compared to acetonitrile are due to the co-operative process of multimers with O-H-O linkage and also the steric hindrance behavior phenomena. The activation entropy (ΔS*), activation enthalpy (ΔH*), Kirkwood correlation factor (gf), Helmholtz energy (ΔFE) parameters have also been determined for propylene glycol and acetonitrile and the results have been correlated

Synthesis and mesomorphic properties of new heterocyclic liquidcrystals with Central Ester–Chalcone linkages

A series of new calamitic liquid crystals, 4-[3-(pyridin-4-yl)prop-2-enoyl]phenyl 4-alkyloxybenzoates, comprising a pyridyl core,ester–chalcone central linkage and terminal alkyloxy chain were synthesized and characterized. This series consists of four membersthat differ by the length of the alkyloxy chain (CnH2n+1O , where n = 10, 12, 14, 16). The structures of the title compounds wereelucidated using spectroscopic and spectrometric techniques, such as FT-IR, NMR (1H and13C) and EI-MS. The mesomorphicproperties were studied using differential scanning calorimetry and optical polarizing microscopy. The decyloxy-containing com-pound was found to be non-mesogenic, whilst the compounds containing n-dodecyloxy to n-hexadecyloxy chains exhibited anenantiotropic smectic A phase with a fan-shaped texture. From the structure–property relationship study, it was proposed that thenumber of carbons in the alkyloxy chain must be at least 12 (n ≥ 12) to generate the smectic phase in the corresponding substitutedArCOOArCOCH CHC5H4N compounds

Wastewater treatment using chitosan and its derivatives: A mini review on latest developments

Effluents and contaminants released from the industries are needed to be treated before releasing them to water bodies. Most common effluents from these industrial wastes are organic compounds, dyes and heavy metals. Heavy metals and their associated anions, as well as organic material, have been separated from wastewaters in industries using a variety of methods. Adsorption is an effective method for water treatment as they are less energy consuming and cost effective. Biopolymers such as chitosan, cellulose, keratin are used for the process of adsorption as they are present abundantly and recyclable. Chitosan is a deacetylated product of chitin. Chitosan and its derivatives are extremely essential due to their abundant availability, low cost, environmental friendliness, and biodegradability and can be widely applied in wastewater treatment. -NH2 and -OH groups are present in chitosan and provide chitosan an opportunity to make physical and chemical modifications. Modifications of chitosan into hydrogels and nanocomposites provide wider applications in wastewater treatment

On the properties of X-ray corona in Seyfert 1 galaxies

We carried out a uniform and systematic analysis of a sample of 112 nearby bright Seyfert 1 type AGN, the observations of which were carried out by the {\it Nuclear Spectroscopic Telescope Array (NuSTAR)} between August 2013 and May 2022. The main goal of this analysis is to investigate the nature of the X-ray corona in Seyfert 1 galaxies. From the physical model that fits the {\it NuSTAR} spectra, we could constrain the high energy cut-off ($\rm{E_{cut}}$) for 73 sources in our sample. For those 73 sources, we fitted the Comptonization model to estimate the temperature ($\rm{kT_{e}}$) of their corona. $\rm{kT_{e}}$ could be constrained in 42 sources. We investigated for possible correlations between various properties of the corona obtained from physical model fits to the observed spectra and between various coronal parameters and physical properties of the sources such as Eddington ratio and black hole mass. We found (a) a strong correlation between $\rm{E_{cut}}$ and the photon index and (b) a significant negative correlation between $\rm{kT_{e}}$ and the optical depth.Comment: 33 pages, 14 figures, Submitted to ApJ, comments are welcom

Accretion Flow Dynamics During 1999 Outburst of XTE J1859+226 - Modeling of Broadband Spectra and Constraining the Source Mass

We examine the dynamical behavior of accretion flow around XTE J1859+226 during the 1999 outburst by analyzing the entire outburst data ($\sim$ 166 days) from RXTE Satellite. Towards this, we study the hysteresis behavior in the hardness intensity diagram (HID) based on the broadband ($3 - 150$ keV) spectral modeling, spectral signature of jet ejection and the evolution of Quasi-periodic Oscillation (QPO) frequencies using the two-component advective flow model around a black hole. We compute the flow parameters, namely Keplerian accretion rate (${\dot m}_d$), sub-Keplerian accretion rate (${\dot m}_h$), shock location ($r_s$) and black hole mass ($M_{bh}$) from the spectral modeling and study their evolution along the q-diagram. Subsequently, the kinetic jet power is computed as $L^{\rm obs}_{\rm jet}\sim 3 - 6 \times 10^{37}$ erg~s$^{-1}$ during one of the observed radio flares which indicates that jet power corresponds to $8-16\%$ mass outflow rate from the disc. This estimate of mass outflow rate is in close agreement with the change in total accretion rate ($\sim 14\%$) required for spectral modeling before and during the flare. Finally, we provide a mass estimate of the source XTE J1859+226 based on the spectral modeling that lies in the range of $5.2 - 7.9 M_{\odot}$ with 90\% confidence.Comment: 12 pages, 8 figures, 3 tables, Accepted for publication in Astrophysics and Space Scienc

Viscoelastic Properties of p-n Alkyl Benzoic Acid Mesogens

Abstract: Dynamic rheological behaviour, such as storage modulus (G') and loss modulus (G'') are measured as a function of frequency at different temperatures in nematic region and also studied linear viscoelastic behaviour of p-n alkyl benzoic acid (nBA) mesogens. Different zones are exhibited by the samples, -a plateau zone at low frequencies, a transition zone at high frequencies and a zone entire plateau showing for crossover frequencies and relaxation times. The dependence of the elastic (G′) and loss (G′′) moduli on frequency is strong. The observed crossover points of G′, G′′ in the study of frequency range is indicating that nematic phase of nBA has behaved like both viscoelastic solid and liquid for small deformations (<1% strain). A typical shear thinning behaviour of viscosity has been displayed when the samples are subjected to shearing at a constant temperature. This typical shear thinning has approached slowly moving to Newtonian viscosity at high shear rates showing progressive development of nematic molecular orientation along flow direction on increasing shear rate. Rheological behaviour of the nBA nematic phases is in general consistent like the other reported compounds except the one thermotropic liquid crystals. The higher shear force and lower viscosity ratio is observed in these compounds in which pentyl benzoic acid has high ratio indicating the high molecular orientation may be due to low chain entanglement