Design and development of Propulsion System for Antitank Guided Missile

A Propulsion system is designed and developed for the third generation antitank guided missile (ATGM). It consists of a separate booster and sustainer. Booster is ahead of sustainer, having four nozzles canted to the missile axis. Sustainer discharges through a supersonic blast tube. Low smoke, high energy nitramine propellant for this propulsion system developed by the High Energy Materials Research Laboratory (HEMRL), Pune, has been successfully flight-tested. The booster grain is tube-in-tube configuration with end inhibition and the sustainer grain is of end burning configuration. High strength aluminium alloy, HE-15, is used for rocket motor components. Glass-phenolic composite ablative material is used for thermal protection of motors and high density graphite is used for nozzle throats. The design considerations and approach, including grain configuration, nozzle, and ignitersare briefly discussed. The propulsion system has been extensively tested in static tests and in flights, establishing the satisfactory performance of the system

Packing-induced conformational and functional changes in the subunits of α-crystallin

The heteroaggregate α-crystallin and homoaggregates of its subunits, αA- and αB-crystallins, function like molecular chaperones and prevent the aggregation of several proteins. Although modulation of the chaperone-like activity of α-crystallin by both temperature and chaotropic agents has been demonstrated in vitro, the mechanism(s) of its regulationin vivo have not been elucidated. The subunits of α-crystallin exchange freely, resulting in its dynamic and variable quaternary structure. Mixed aggregates of the α-crystallins and other mammalian small heat shock proteins (sHSPs) have also been observedin vivo. We have investigated the time-dependent structural and functional changes during the course of heteroaggregate formation by the exchange of subunits between homoaggregates of αA- and αB-crystallins. Native isoelectric focusing was used to follow the time course of subunit exchange. Circular dichroism revealed large tertiary structural alterations in the subunits upon subunit exchange and packing into heteroaggregates, indicating specific homologous and heterologous interactions between the subunits. Subunit exchange also resulted in quaternary structural changes as demonstrated by gel filtration chromatography. Interestingly, we found time-dependent changes in chaperone-like activity against the dithiothreitol-induced aggregation of insulin, which correlated with subunit exchange and the resulting tertiary and quaternary structural changes. Heteroaggregates of varying subunit composition, as observed during eye lens epithelial cell differentiation, generated by subunit exchange displayed differential chaperone-like activity. It was possible to alter chaperone-like activity of preexisting oligomeric sHSPs by alteration of subunit composition by subunit exchange. Our results demonstrate that subunit exchange and the resulting structural and functional changes observed could constitute a mechanism of regulation of chaperone-like activity of α-crystallin (and possibly other mammalian sHSPs) in vivo

Planetary Nebulae with Ultra-Violet Imaging Telescope (UVIT): Far Ultra-violet halo around the Bow Tie nebula (NGC 40)

Context. NGC 40 is a planetary nebula with diffuse X-ray emission, suggesting an interaction of the high speed wind from WC8 central star (CS) with the nebula. It shows strong Civ 1550 {\AA} emission that cannot be explained by thermal processes alone. We present here the first map of this nebula in C IV emission, using broad band filters on the UVIT. Aims. To map the hot C IV emitting gas and its correspondence with soft X-ray (0.3-8 keV) emitting regions, in order to study the shock interaction with the nebula and the ISM. This also illustrates the potential of UVIT for nebular studies. Methods. Morphological study of images of the nebula obtained at an angular resolution of about 1.3" in four UVIT filter bands that include C IV 1550 {\AA} and C II] 2326 {\AA} lines and UV continuum. Comparisons with X-ray, optical, and IR images from literature. Results. The C II] 2326 {\AA} images show the core of the nebula with two lobes on either side of CS similar to [N II]. The C IV emission in the core shows similar morphology and extant as that of diffuse X-ray emission concentrated in nebular condensations. A surprising UVIT discovery is the presence of a large faint FUV halo in FUV Filter with {\lambda}eff of 1608 {\AA}. The UV halo is not present in any other UV filter. FUV halo is most likely due to UV fluorescence emission from the Lyman bands of H2 molecules. Unlike the optical and IR halo, FUV halo trails predominantly towards south-east side of the nebular core, opposite to the CS's proper motion direction. Conclusions. Morphological similarity of C IV 1550 {\AA} and X-ray emission in the core suggests that it results mostly from interaction of strong CS wind with the nebula. The FUV halo in NGC 40 highlights the existence of H2 molecules extensively in the regions even beyond the optical and IR halos.Comment: 4 pages, 5 figures, accepted for publication as a letter in Astronomy & Astrophysic

Planetary Nebulae with UVIT II: Revelations from FUV vision of Butterfly Nebula NGC 6302

The high excitation planetary nebula, NGC 6302, has been imaged in two far-ultraviolet (FUV) filters, F169M (Sapphire; {\lambda}$_{\rm eff}$: 1608 {\AA}) and F172M (Silica; {\lambda}$_{\rm eff}$: 1717 {\AA}) and two NUV filters, N219M (B15; {\lambda}$_{\rm eff}$: 2196 {\AA}) and N279N (N2; {\lambda}$_{\rm eff}$: 2792 {\AA}) with the Ultra Violet Imaging Telescope (UVIT). The FUV F169M image shows faint emission lobes that extend to about 5 arcmin on either side of the central source. Faint orthogonal collimated jet-like structures are present on either side of the FUV lobes through the central source. These structures are not present in the two NUV filters nor in the FUV F172M filter. Optical and IR images of NGC 6302 show bright emission bipolar lobes in the east-west direction with a massive torus of molecular gas and dust seen as a dark lane in the north-south direction. The FUV lobes are much more extended and oriented at a position angle of 113{\deg}. They and the jet-like structures might be remnants of an earlier evolutionary phase, prior to the dramatic explosive event that triggered the Hubble type bipolar flows approximately 2200 years ago. The source of the FUV lobe and jet emission is not known, but is likely due to fluorescent emission from H$_2$ molecules. The cause of the difference in orientation of optical and FUV lobes is not clear and, we speculate, could be related to two binary interactions.Comment: 9 pages, 5 figures, accepted for publication in Astronomy & Astrophysic

Degenerating families of rank two bundles

We construct families of rank two bundles εton P4, in characteristic two, where for t ≠ 0 , εt is a sum of line bundles, and ε0 is non-split. We construct families of rank two bundles εt on P3, in characteristic p, where for t ≠ 0, εt is a sum of line bundles, and ε0 is non-split

Evolution of Minimally Invasive Surgery for Donor Nephrectomy and Outcomes

Modifications to the laparoscopic donor nephrectomy technique may increase this option to donors who may have been considered unsuitable heretofore