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Arp 65 interaction debris: massive H I displacement and star formation
Sengupta, C.,Scott, T. C.,Paudel, S.,Saikia, D. J.,Dwarakanath, K. S.,Sohn, B. W. EDP Sciences 2015 Astronomy and astrophysics Vol.584 No.-
<P>Context. Pre?merger tidal interactions between pairs of galaxies are known to induce significant changes in the morphologies and kinematics of the stellar and interstellar medium components. Large amounts of gas and stars are often found to be disturbed or displaced as tidal debris. This debris then evolves, sometimes forming stars and occasionally forming tidal dwarf galaxies. Here we present results from our HI study of Arp 65, an interacting pair hosting extended HI tidal debris. Aims. In an effort to understand the evolution of tidal debris produced by interacting pairs of galaxies, including in situ star and tidal dwarf galaxy formation, we are mapping HI in a sample of interacting galaxy pairs. The Arp 65 pair is the latest member of this sample to be mapped. Methods. Our resolved HI 21 cm line survey is being carried out using the Giant Metrewave Radio Telescope. We used our HI survey data as well as available SDSS optical, Spitzer infra-red and GALEX UV data to study the evolution of the tidal debris and the correlation of HI with the star-forming regions within it. Results. In Arp 65 we see a high impact pre?merger tidal interaction involving a pair of massive galaxies (NGC90 and NGC93) that have a stellar mass ratio of ~1:3. The interaction, which probably occurred ~1.02.5 × 10<SUP>8</SUP> yr ago, appears to have displaced a large fraction of the HI in NGC90 (including the highest column density HI) beyond its optical disk. We also find extended on-going star formation in the outer disk of NGC90. In the major star-forming regions, we find the HI column densities to be ~4.7 × 10<SUP>20</SUP> cm<SUP>−2</SUP> or lower. But no signature of star formation was found in the highest column density HI debris SE of NGC90. This indicates conditions within the highest density HI debris remain hostile to star formation and it reaffirms that high HI column densities may be a necessary but not sufficient criterion for star formation.</P>
Highly stereoselective synthesis of mupirocin H
Sengupta, S.,Kim, H.J.,Cho, K.S.,Song, W.Y.,Sim, T. Pergamon Press 2017 Tetrahedron Vol.73 No.8
A highly diastereoselective and efficient convergent synthesis of mupirocin H starting from (+)-®-Roche ester was achieved. Grubbs cross metathesis was employed as the key step in the pathway to generate an important E-olefin intermediate. Other processes utilized in the route include a Pd-catalysed stereoselective substitution reaction of a cis epoxide, Sharpless epoxidation followed by Red-Al promoted epoxide ring opening, and Seebach methylation and a TEMPO/BAIB mediated oxidation-lactonization sequence. Finally, we observed that mupirocin H inhibits SbnE, a synthetase required for staphyloferrin B biosynthesis.
Ahmed T Alahmar,Pallav Sengupta,Sulagna Dutta,Aldo E. Calogero 대한생식의학회 2021 Clinical and Experimental Reproductive Medicine Vol.48 No.2
Objective: Oxidative stress (OS) plays a key role in the etiology of unexplained male infertility. Coenzyme Q10 (CoQ10) is a potent antioxidant that may improve semen quality and OS in infertile men with idiopathic oligoasthenoteratospermia (OAT), but the underlying mechanism is unknown. Therefore, the present study was undertaken to investigate the effect of CoQ10 on OS markers and sperm DNA damage in infertile patients with idiopathic OAT. Methods: This prospective controlled study included 50 patients with idiopathic OAT and 50 fertile men who served as controls. All patients underwent a comprehensive medical assessment. Patients and controls received 200 mg of oral CoQ10 once daily for 3 months. Semen and blood were collected and analyzed for sperm parameters, seminal CoQ10 levels, reactive oxygen species (ROS) levels, total antioxidant capacity, catalase, sperm DNA fragmentation (SDF), and serum hormonal profile. Results: The administration of CoQ10 to patients with idiopathic OAT significantly improved sperm quality and seminal antioxidant status and significantly reduced total ROS and SDF levels compared to pre-treatment values. Conclusion: CoQ10, at a dose of 200 mg/day for 3 months, may be a potential therapy for infertile patients with idiopathic OAT, as it improved sperm parameters and reduced OS and SDF in these patients.
Arp 202: a TDG formed in a parent's extended dark matter halo?
Scott, T C,Lagos, P,Ramya, S,Sengupta, C,Paudel, S,Sahu, D K,Misra, K,Woo, J -H,Sohn, B W Oxford University Press 2018 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.475 No.1
<P>We report on H alpha+ [N II] imaging of the Arp 202 interacting pair and its tidal dwarf galaxy (TDG) candidate as well as a GMOS long slit spectrum from the TDG candidate, observed with the Gemini North telescope. Our H alpha + [N II] imaging reveals the TDG to have an elongated structure, similar to 1.9 kpc in length with the two principal star-forming knots at either end. Our observations also show the TDG candidate has a recessional V-H alpha similar to 3032km s(-1), within 100 km s(-1) of the parent pair's mean velocity and an oxygen abundance of 12+log(O/H) = 8.10 +/- 0.41. The TDG's oxygen abundance is in good agreement with that of a star-forming region in NGC 2719A, one of the parent galaxies, which has an estimated oxygen abundance of 12+log(O/H) = 8.05 +/- 0.41. The TDG's V-H alpha and oxygen abundance confirm previous results validating the candidate as a TDG. The absence of detectable emission from the TDG in Spitzer 3.6 and 4.5 vim images together with the lack of absorption lines and weak continuum in the spectrum is consistent with absence the of an old population (greater than or similar to 0.5 Gyr). The location of the TDG within the interaction debris and the absence of indicators of an old stellar population in the TDG is consistent with a scenario in which the TDG is formed from H I stripped from the parent galaxies and within the extended dark matter halo of one of the parents as proposed by Bournaud et al. and Duc et al.</P>
Coenzyme Q10, oxidative stress, and male infertility: A review
Ahmed T. Alahmar,Aldo E. Calogero,Rajender Singh,Rossella Cannarella,Pallav Sengupta,Sulagna Dutta 대한생식의학회 2021 Clinical and Experimental Reproductive Medicine Vol.48 No.2
Male infertility has a complex etiopathology, which mostly remains elusive. Although research has claimed that oxidative stress (OS) is the most likely underlying mechanism of idiopathic male infertility, the specific treatment of OS-mediated male infertility requires further investigation. Coenzyme Q10 (CoQ10), a vitamin-like substance, has been found in measurable levels in human semen. It exhibits essential metabolic and antioxidant functions, as well as playing a vital role in mitochondrial bioenergetics. Thus, CoQ10 may be a key player in the maintenance of biological redox balance. CoQ10 concentrations in seminal plasma directly correlate with semen parameters, especially sperm count and sperm motility. Seminal CoQ10 concentrations have been shown to be altered in various male infertility states, such as varicocele, asthenozoospermia, and medical or surgical regimens used to treat male infertility. These observations imply that CoQ10 plays an important physiological role in the maintenance and amelioration of semen quality. The present article thereby aimed to review the possible mechanisms through which CoQ10 plays a role in the regulation of male reproductive function, and to concisely discuss its efficacy as an ameliorative agent in restoring semen parameters in male infertility, as well as its impact on OS markers, sperm DNA fragmentation, pregnancy, and assisted reproductive technology outcomes.
Alahmar Ahmed T.,Calogero Aldo E.,Sengupta Pallav,Dutta Sulagna 대한남성과학회 2021 The World Journal of Men's Health Vol.39 No.2
Purpose: Oxidative stress and sperm DNA fragmentation (SDF) are potential contributing factors for idiopathic male infertility. Coenzyme Q10 (CoQ10) have been reported to be effective in the treatment of idiopathic male infertility, in general, owing to its antioxidant properties. Thus, the present study intends to investigate the effects of CoQ10 therapy on semen parameters, oxidative stress markers and SDF in infertile men, specifically with idiopathic oligoasthenozoospermia (OA). Materials and Methods: In this case-control study, sixty-five infertile patients with idiopathic OA and forty fertile men (control) were included. All participants underwent semen analysis based on the World Health Organization guidelines (5th edition, 2010). Patients received CoQ10 at the dose of 200 mg/d orally for three months. Seminal plasma CoQ10, total antioxidant capacity (TAC), total reactive oxygen species (ROS), glutathione peroxidase (GPx), and SDF levels were measured in controls (baseline) and infertile patients pre- and post-CoQ10 treatment. Results: CoQ10 treatment for three months significantly improved sperm concentration (p<0.05), progressive motility (p<0.05), total motility (p<0.01), seminal fluid CoQ10 concentration (p<0.001), TAC (p<0.001), and GPx (p<0.001) levels in infertile men with OA. Further, ROS level (p<0.05) and SDF percentage (p<0.001) were reduced in OA patients as compared to the baseline. CoQ10 levels also correlated positively with sperm concentration (r=0.48, p=0.01) and total motility (r=0.59, p=0.003) while a negative correlation was recorded between SDF and sperm motility (r=-0.54, p=0.006). Conclusions: CoQ10 supplementation for three months could improve semen parameters, oxidative stress markers and reduce SDF in infertile men with idiopathic OA.