Effects of γ-rays on DNA-cholesterol complex

Summary Effects of -rays on the DNA-cholesterol complex have been studied. Radiation-induced changes are found and compared with those on DNA-dye or drug complexes.Acknowledgment. Thanks are due to P. K. Roy, K. L. Bhattacharya and K. M. Khanna (Department of Physics, Birla Institute of Technology, Ranchi) for helpful discussions and the Chittaranjan Cancer Hospital (Calcutta) for irradiation facilities.     

Development of a new coated electrode with low nickel content for welding ductile iron and its response to austempering

Coated Electrodes with small amounts of nickel were developed for welding ductile iron (DI) and conversion of the same into austempered ductile iron (ADI) after austempering. Among six electrodes, Trials 3 and 4 were selected for establishing crack-free weld deposits via preheating and post-weld heat treatment. Austenitization was performed at 900℃ for 2 h and austempering at 300 or 350℃ for three different holding times to observe the results of austempering with respect to the microstructure, hardness, and austempering kinetics of the samples. The microstructures of the weld deposits showed needle-like bainitic ferrite with small amounts of retained austenite when treated at 300℃ and feathery bainitic ferrite with large amounts of retainedaustenite when treated at 350℃. The electrode labeled with Trial 3 revealed greater austenite contents than that labeled with Trial 4 when treated with a 2 h holding time regardless of the austempering temperature applied. The transformation rate of the bainitic ferrite of Trial 3 was relatively higher than that of Trial 4 and showed a lower rate constant, leading to a higher diffusion rate of carbon in austenite.     

Synthesis and characterization of copper foams through a powder metallurgy route using a compressible and lubricant space-holder material

In the present work, a compressible and lubricating space-holder material commonly known as “acrawax” was used to process Cu foams with various pore sizes and various porosities. The foams were processed without using binders to avoid contamination of their metal matrices. The lubricant space-holder material was found to facilitate more uniform flow and distribution of metal powder around the surface of the space holder. In addition, the use of acrawax as a space-holder material yielded considerably dense cell walls, which are an essential prerequisite for better material properties. The foams processed with a smaller-sized space holder were found to exhibit better electrical and mechanical properties than those processed with a coarser-sized space holder. The isotropic pore shape, uniform pore distribution throughout the metal matrix, and uniform cell wall thickness were found to enhance the properties pertaining to fine-pore foam samples. The processed foams exhibit properties similar to those of the foams processed through the lost-carbonate sintering process.     

Karkata,a new genus of gecarcinucid freshwater crab with two new species,and four new species of Pilarta Bahir and Yeo, 2007 and Cylindrotelphusa Alcock, 1909 (Decapoda: Brachyura) from Kerala,India

A new genus of freshwater crab, Karkata gen. nov., with two species, K. ghanarakta sp. nov. (type species) and K. kusumbha sp. nov., and two new species each of Pilarta Bahir and Yeo, 2007 (P. aroma sp. nov. and P. punctatissima sp. nov.) and Cylindrotelphusa Alcock, 1909 (C. breviphallus sp. nov. and C. longiphallus sp. nov.), are described from Kerala, India. Additionally, C. granulata (Pillai, 1951) comb. et stat. nov. is recognised as a distinct species. Karkata gen. nov. is distinguished from other Indian gecarcinucid genera by a suite of carapace and gonopod characters, including a moderately arched, smooth carapace, the presence of a prominent suture between male thoracic sternites 2, 3 and 3, 4, the absence of a flagellum on the third maxilliped exopod, a very short terminal segment of the male first gonopod (G1), and a short distal segment of the male second gonopod (G2). Karkata ghanarakta sp. nov. is differentiated from K. kusumbha sp. nov. by the shape of the G1 subterminal segment and its live colouration. Pilarta punctatissima sp. nov. is distinct among the congeners mainly by its densely punctate carapace, densely setose anterolateral and posterolateral margins of the carapace, stouter G1 terminal segment, and relatively long G2 distal segment whereas P. aroma sp. nov. can be separated from P. anuka Bahir and Yeo, 2007 by its relatively smooth carapace, deep H-shaped groove, relatively long G1 terminal segment, and almost straight outer margins of the G1 terminal and subterminal segments. Cylindrotelphusa breviphallus sp. nov. is differentiated from C. longiphallus sp. nov. and C. steniops (Alcock, 1909) by its stout G1, with a stout, short terminal segment. Cylindrotelphusa longiphallus sp. nov. is distinguished from the congeners by its shallow, narrow cervical grooves and relatively slender ambulatory legs. An identification key to the species of Karkata, Pilarta and Cylindrotelphusa is provided.

http://zoobank.org/urn:lsid:zoobank.org:pub:AB9B01DA-B23F-4AC2-9349-75ADDBBBF707     

The afterglow of GRB 050709 and the nature of the short-hard gamma-ray bursts

The final chapter in the long-standing mystery of the gamma-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolution in our understanding of long-duration GRBs that followed the discovery in 1997 of their broadband (X-ray, optical and radio) afterglow emission. Here we present the discovery of the X-ray afterglow of a short-hard burst, GRB 050709, whose accurate position allows us to associate it unambiguously with a star-forming galaxy at redshift z = 0.160, and whose optical lightcurve definitively excludes a supernova association. Together with results from three other recent short-hard bursts, this suggests that short-hard bursts release much less energy than the long-duration GRBs. Models requiring young stellar populations, such as magnetars and collapsars, are ruled out, while coalescing degenerate binaries remain the most promising progenitor candidates.     

Structural basis of HutP-mediated anti-termination and roles of the Mg2+ ion and L-histidine ligand

HutP regulates the expression of the hut structural genes of Bacillus subtilis by an anti-termination mechanism and requires two components, Mg2+ ions and L-histidine. HutP recognizes three UAG triplet units, separated by four non-conserved nucleotides on the terminator region. Here we report the 1.60-A resolution crystal structure of the quaternary complex (HutP-L-histidine-Mg2+-21-base single-stranded RNA). In the complex, the RNA adopts a novel triangular fold on the hexameric surface of HutP, without any base-pairing, and binds to the protein mostly by specific protein-base interactions. The structure explains how the HutP and RNA interactions are regulated critically by the l-histidine and Mg2+ ion through the structural rearrangement. To gain insights into these structural rearrangements, we solved two additional crystal structures (uncomplexed HutP and HutP-L-histidine-Mg2+) that revealed the intermediate structures of HutP (before forming an active structure) and the importance of the Mg2+ ion interactions in the complexes.     

Sterilization of solanaceous hadda,Epilachna vigintioctopunctata F. by irradiating pupae using gamma radiation

Summary Sterility in males and females was observed in the resulting adults when 3–4-day-old pupae of solanaceous hadda,Epilachna vigintioctopunctata F. were exposed to gamma radiation doses of 2000 rad and 2500 rad. However, at 2500 rad longevity of treated insects was adversely affected.Acknowledgment. Financial help to one of us (J.K.G.) by C.S.I.R. in the form of J.R.F. is gratefully acknowledged. Authors are thankful to Prof. P.N. Srivastava and Dr A.R. Rao, School of Life Sciences, J.N.U. Delhi for providing radiation facility.