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Microstructure and mechanical properties of similar and dissimilar metal gas tungsten constricted arc welds:Maraging steel to 13-8 Mo stainless steel

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Defence Technology（防务技术） 2019年第1期15卷 111-121页

作者： C.v.s.Murthy A.gopala krishna G.M.Reddy Defence Research and Development Laboratory Jawaharlal Nehru Technological University Defence Metallurgical Research Laboratory

Maraging steel (250) and 13-8 Mo stainless steel plates were joined by gas tungsten constricted arc welding(GTCAW) process in similar and dissimilar metal combinations using 13-8 Mo stainless steel filler wire. The similar and dissimilar metal welds made in solutionized condition were subjected to standard post weld hardening treatments direct ageing at 485 ℃, soaking for 31/2 hours followed by air cooling(ageing treatment of maraging steel) and direct ageing at 510 ℃, soaking for 4 h followed by air cooling(ageing treatment of 13-8 Mo stainless steel). The joint characterization studies include microstructure examination, microhardness survey across the weldments and transverse weld tensile *** and dissimilar metal weldments responded to both the post weld ageing treatment. After post weld aging, increase in yield strength, UTs and slight reduction in % elongation of similar and dissimilar metal were observed. The observed tensile properties were correlated with microstructure and hardness distribution across the welds.

关键词： Maraging steel(250) 13-8 Mo stainless steel Mechanical properties Microstructure

Corrosion behavior of ultrafine-grained AA2024 aluminum alloy produced by cryorolling

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International Journal of Minerals,Metallurgy and Materials 2017年第11期24卷 1293-1305页

作者： P. Laxman Mani kanta v.C. srivastava k. venkateswarlu sharma Paswan B. Mahato Goutam Das k. sivaprasad k. gopala krishna Department of Metallurgical & Materials Engineering National Institute of Technology Thiruchirappalli 620015 India National Metallurgical Laboratory Council of Scientific & Industrial Research Jamshedpur 831007 India National Aerospace Laboratories Council of Scientific & Industrial Research Bangalore 560017 India

The objectives of this study were to produce ultrafine-grained(UFG) AA2024 aluminum alloy by cryorolling followed by aging and to evaluate its corrosion behavior. solutionized samples were cryorolled to ~85% reduction in thickness. subsequent aging resulted in a UFG structure with finer precipitates of Al_2CuMg in the cryorolled alloy. The(1) solutionized and(2) solutionized and cryorolled samples were uniformly aged at 160°C/24 h and were designated as CGPA and CRPA, respectively; these samples were subsequently subjected to corrosion studies. Potentiodynamic polarization studies in 3.5 wt% NaCl solution indicated an increase in corrosion potential and a decrease in corrosion current density for CRPA compared to CGPA. In the case of CRPA, electrochemical impedance spectroscopic studies indicated the presence of two complex passive oxide layers with a higher charge transfer resistance and lower mass loss during intergranular corrosion tests. The improved corrosion resistance of CRPA was mainly attributed to its UFG structure, uniform distribution of fine precipitates, and absence of coarse grain-boundary precipitation and associated precipitate-free zones as compared with the CGPA alloy.

关键词： AA2024 alloy cryorolling ultrafine grains precipitation corrosion behavior

Hepatoprotective activity of Hepax-A polyherbal formulation

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Asian Pacific Journal of Tropical Biomedicine 2011年第2期1卷 142-146页

作者： vC Devaraj B gopala krishna GL viswanatha Jagadish v kamath sanjay kumar Department of Pharmacology Krupanidhi College of Pharmacy Department of Pharmacognosy RR College of Pharmacy Department of Pharmacology PES College of Pharmacy

Objective:To evaluate the hepatoprotective potential of Hepax,a polyherbal formulation,against three experimentally induced hepatotoxicity models in ***:Hepatoprotective activity of Hepax was studied against three experimentally induced hepatotoxicity models,namely, carbon tetrachloride(CCl_4),paracetamol and thiocetamide induced hepatotoxicity in rats. Results:Administration of hepatotoxins(CCl_4,paracetamol and thiocetamide) showed significant morphological,biochemical and histological deteriorations in the liver of experimental animals. Pretreatment with Hepax had significant protection against hepatic damage by maintaining the morphological parameters(liver weight and liver weight to organ weight ratio) within normal range and normalizing the elevated levels of biochemical parameters(sGPT,sCOT,ALP and total bilirubin),which were evidently showed in histopathological ***:The Hepax has highly significant hepatoprotective effect at 100 and 200 mg/kg,*** the liver of all the three experimental animal models.

关键词： Hepax Paracetamol CCl_4 Thiocetamide Hepatotoxicity

Polarizabilities and Orientational Order Parameter in N-(p-n-Ethoxybenzylidene)- p-n-Alkoxy Anilines, *** LC Compounds

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Journal of surface Engineered Materials and Advanced Technology 2016年第3期6卷 134-148页

作者： Putcha srinivasa sastry Chintalapati srinivas Pokkunuri Pardhasaradhi venkata gopala krishna Murthy Pisipati Department of Physics Krishna University Machilipatnam India Department of Physics A. L. College Vijayawada India Liquid Crystal Research Centre Department of Electronics and Communications Engineering Koneru Lakshmaiah University Vaddeswaram India

n.m, ***, nO.m and *** compounds play an important role in the fundamental and applied aspects. As a part of our systematic studies of the above homologous series regarding the synthesis, characterization and phase transition studies, here the authors report the polarizabilities and orientational order parameter, s in N-(p-n-ethoxybenzylidene)-p-n-alkoxy anilines, *** with m = 3 to 10 liquid crystalline compounds except with m = 5 which has been already published. The rest of the compounds exhibit the nematic LC phase except with m = 10 which shows the smectic-C phase along the nematic phase which is originally not detected by Godzwon et al. But the author’s observations with TM and differential scanning calorimeter have shown the existence on smC phase in addition to nematic phase. Further, smC is clarified using the histogram technique whose details are given below and are published elsewhere. The orientstonal order parameter, s is estimated using different methods and compared with the value obtained from birefringence, δn = (nsub>esub> – nsub>osub>) where no field model is used. It is observed in these compounds case as in other LC compounds vuks isotropic model is favored compared to that of anisotropic model proposed by Neugebauer.

关键词： Orientstonal Order Parameter s 2O.Om LC Compounds vuks Isotropic Model Neugebauer Anisotropic Model Nematic Phase

源自印度药用植物的一种抗溃疡复方制剂(英文)

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中国天然药物 2013年第2期11卷 145-148页

作者： v.C. Devaraj B.gopala krishna Department of Pharmacology Bioneeds Pre Clinical Services Department of Pharmacognosy RR College of Pharmacy

AIM: The present study was aimed at evaluating the antiulcer activity of the polyherbal formulation (PHF) containing the leaf extracts of Moringa oleifera, Raphinus sativus, and Amaranthus tricolor in rats. METHODs: The antiulcer activity of the polyherbal formulation (PHF) was evaluated using different models of gastric ulcers: ethanol-induced, indomethacin-induced and ischemia reperfusion-induced gastric ulcers. Efficacy was assessed by determining the ulcer index. REsULTs: Administration of the polyherbal formulation (150mg·kg-1 , p.o.) offered significant protection against indomethacin-induced, ethanol-induced, and ischemic reperfusion-induced ulcer models when compared to the control group. CONCLUsION: PHF, containing leaf extracts of Moringa oleifera, Raphinus sativus, and Amaranthus tricolor, was found to possess antiulcer properties in three experimental animal models of gastric ulcers, and these findings suggest that the significant gastroprotective activity could be mediated by its antioxidant activity.

关键词： Gastric ulcer Ulcer index Polyherbal formulation Indomethacin Ethanol