Hot Isostatic Pressing Technology for Defence and Space Applications

Hot isostatic pressing (HIP) technology has been established for the development of AISI-304 stainless steel and nickel base superalloy Inconel 718 integral turbine rotors, for liquid propulsion engine of Prithvi missile, and cryoengine of geostationary satellite launch vehicle (GSLV), respectively. Before making the full size rotors, the structure – property relationships in hot isostatic pressed (HIPed) 304 stainless steel and superalloy 718 were established. The HIPed steel and superalloy have shown near 100 per cent theoretical density, homogeneous, and fine grained microstructure. Their mechanical properties were found to be in agreement with those specified for the integral turbine rotors and hence, development of full size near net shaped integral turbine rotors was undertaken. The HIPed steel rotors subjected to the static engine tests have shown a satisfactory performance, and therefore a large number of rotors could be produced to fulfill the requirement of target labs. The HIP technology for the integral turbine rotors was found to be cost effective (about 50 per cent) over the conventional fabrication method which involves forging, machining, and welding of blades to the disk. The processing, structure, and properties of the HIPed 304 stainless steel and superalloy 718 in relation to the performance of integral turbine rotors for missile and space vehicle applications are discussed in this paper.Defence Science Journal, 2012, 62(1), pp.73-80, DOI:http://dx.doi.org/10.14429/dsj.62.37

On the (parameterized) complexity of recognizing well-covered (r,l)-graphs.

An (r,ℓ)(r,ℓ)-partition of a graph G is a partition of its vertex set into r independent sets and ℓℓ cliques. A graph is (r,ℓ)(r,ℓ) if it admits an (r,ℓ)(r,ℓ)-partition. A graph is well-covered if every maximal independent set is also maximum. A graph is (r,ℓ)(r,ℓ)-well-covered if it is both (r,ℓ)(r,ℓ) and well-covered. In this paper we consider two different decision problems. In the (r,ℓ)(r,ℓ)-Well-Covered Graph problem ((r,ℓ)(r,ℓ) wcg for short), we are given a graph G, and the question is whether G is an (r,ℓ)(r,ℓ)-well-covered graph. In the Well-Covered (r,ℓ)(r,ℓ)-Graph problem (wc (r,ℓ)(r,ℓ) g for short), we are given an (r,ℓ)(r,ℓ)-graph G together with an (r,ℓ)(r,ℓ)-partition of V(G) into r independent sets and ℓℓ cliques, and the question is whether G is well-covered. We classify most of these problems into P, coNP-complete, NP-complete, NP-hard, or coNP-hard. Only the cases wc(r, 0)g for r≥3r≥3 remain open. In addition, we consider the parameterized complexity of these problems for several choices of parameters, such as the size αα of a maximum independent set of the input graph, its neighborhood diversity, or the number ℓℓ of cliques in an (r,ℓ)(r,ℓ)-partition. In particular, we show that the parameterized problem of deciding whether a general graph is well-covered parameterized by αα can be reduced to the wc (0,ℓ)(0,ℓ) g problem parameterized by ℓℓ, and we prove that this latter problem is in XP but does not admit polynomial kernels unless coNP⊆NP/polycoNP⊆NP/poly

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

PaLM: Scaling Language Modeling with Pathways

Large language models have been shown to achieve remarkable performance across a variety of natural language tasks using few-shot learning, which drastically reduces the number of task-specific training examples needed to adapt the model to a particular application. To further our understanding of the impact of scale on few-shot learning, we trained a 540-billion parameter, densely activated, Transformer language model, which we call Pathways Language Model PaLM. We trained PaLM on 6144 TPU v4 chips using Pathways, a new ML system which enables highly efficient training across multiple TPU Pods. We demonstrate continued benefits of scaling by achieving state-of-the-art few-shot learning results on hundreds of language understanding and generation benchmarks. On a number of these tasks, PaLM 540B achieves breakthrough performance, outperforming the finetuned state-of-the-art on a suite of multi-step reasoning tasks, and outperforming average human performance on the recently released BIG-bench benchmark. A significant number of BIG-bench tasks showed discontinuous improvements from model scale, meaning that performance steeply increased as we scaled to our largest model. PaLM also has strong capabilities in multilingual tasks and source code generation, which we demonstrate on a wide array of benchmarks. We additionally provide a comprehensive analysis on bias and toxicity, and study the extent of training data memorization with respect to model scale. Finally, we discuss the ethical considerations related to large language models and discuss potential mitigation strategies

Designing of some novel metallo antibiotics tuning biochemical behaviour towards therapeutics: Synthesis, characterisation and pharmacological studies of metal complexes of cefixime

Cefixime is a broad spectrum semi synthetic cephalosporin antibiotic for oral administration. Metal complexes of cefixime with Cu(II), Zn(II), Cd(II), Fe(III) and Ni(II) have been synthesised and characterised by elemental analysis and IR, UV–Vis., NMR and ESR spectra. The electronic spectral behaviour and cyclic voltammetric studies have been carried out on the interaction of metal complexes with calf thymus DNA. The results suggest that the complexes can bind to DNA by intercalation mode. The Cu(II), Zn(II), Cd (II) and Ni(II) complexes exhibit square planar geometry. Fe(III) complex exhibits octahedral geometry. The complexes showed a slightly higher antimicrobial activity than the cefixime drug. Among the metal complexes, Fe(III) was found to be more active than other complexes when tested against bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the disc diffusion method. SEM analysis provides the morphology of the metal complexes. The DNA binding interaction of metal complexes with CT DNA using the cyclic voltammetry technique and their salient features are discussed

Multiple equilibrium studies on some zinc (II) mixed ligand complex systems

793-795Multiple equilibrium studies involved in some Zn(II) ternary systems viz. Zn(II)--cysteine (cys)/-pencillamine (pen)/-cysteic acid (cya) (A)--2,3-diaminopropionic acid (dapa), -2,4-diaminobutyric acid (daba) and -ornithine (orn) (B) by the computer analysis of the pH titration data have shown the presence of ZnABH2, ZnABH or ZnAB type ternary species. The trends in the results demonstrate the possibility of attachment of an extra proton in the ZnABH species to be with ligand (B). In the ZnABH2 species, one proton resides with ligand (A) and the other with ligand (B). The mode of coordination of cys, pen, dapa, daba and orn ligands in the ZnAB type species is similar to their coordination in the corresponding binary species. However, in the ZnAB and ZnABH species in.the Zn(II)-cya(A)-dapa, daba and orn (B) systems, cya (A) ligand binds the metal in a glycinelike mode though it is monodentate in its ZnA and ZnA2 binary species

Coordination behaviour of glycylglycine with zinc(II) in presence of <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-histidine, histamine and imidazole ligands

581-584Computer-based analysis of the pH titrations data obtained in aqueous perchlorate media at 37ᵒC and 1=0.15 mol dm-3 (NaClO4) for the zinc(II)-glycylglycine/glycinamide (A)--histidine and histamine (B) mixed ligand systems shows the presence of the mixed ligand species ZnABH and ZnAB, ZnAB arid ZnAB2 mixed species are formed in the zinc(II)-glycylglycine/glycinamide (A)-imidazole (B) systems. There is no evidence for the formation of the zinc(II) binary and mixed ligand species containing amide deprotonated dipeptide below pH 7.5. The results indicate that the dipeptide binds the metal through N-amino and O-peptido groups in the ZnABH and ZnAB mixed species as also in the ZnA or ZnA2 type of binary species. In the ZnABH species the extra proton is attached to the primary amino group of the -histidine or histamine secondary ligand (B). The carboxylate group of -histidine is also involved in coordination in both the ZnAB and ZnABH types of mixed species. It appears that the ZnAB2 species is more stable than the ZnAB species in the zinc(II)-glycylglycine/glycinamide (A)-imidazole (B)

Studies on the stabilities of some mixed ligand complexes of nickel(II) involving dopamine/dopa and sulphur containing ligands

194-196<span style="font-size:12.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">Stability constants for the mixed ligand species of the types NiAB, NiABH and NiABH2 (where A=dopamine and dopa; <span style="font-size:12.0pt; font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">B=L-cysteine, D-penicilamine and L-cysteic acid) have been detennined. In the NiAB, the mode of coordination of A and B is exactly <span style="font-size:12.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">similar to their binding in the respective binary complexes. In NiABH, the extra proton is attached to A. In NiABH2 (where A=dopamine) one proton is attached to A and other resides with B, while in the NiABH2 (where A=dopa) both the protons are with dopa.</span

Initial-stage sintering kinetics of nanocrystalline tungsten

Initial-stage sintering kinetics of nanocrystalline tungsten has been studied in the temperature range of 1273-1473 K (1000-1200 °C). Nanocrystalline tungsten sinters initially through a grain boundary diffusion mechanism. The calculated activation energy was 388 ± 11 kJ/mol at low temperatures (1273-1373 K (1000-1100 °C)) and 409 ± 7 kJ/mol at high temperatures (1373-1473 K (1100-1200 °C)), which are close to the experimentally measured activation energy for grain boundary diffusion (385 kJ/mol)