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Rietveld refinement of powder X-ray diffraction,microstructural and mechanical studies of magnesium matrix composites processed by high energy ball milling

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Journal of magnesium and Alloys 2018年第4期6卷 390-398页

作者： T.Ramkumar m.selvakumar R.Vasanthsankar A.S.Sathishkumar P.Narayanasamy G.Girija Department of mechanical Engineering Dr.Mahalingam College of Engineering and TechnologyPollachi 642003India Department of Automobile Engineering Dr.Mahalingam College of Engineering and TechnologyPollachi 642003India Department of mechanical Engineering Sree Sowdambika College of EngineeringAruppukottai 626134India Department of mechanical Engineering Kamaraj College of Engineering and TechnologyVirudhunagar 626001India

This research reports the processing of magnesium matrix composites reinforced with silicon carbide(SiC)and aluminium oxide(Al_(2)O_(3))using powder metallurgy technique through high energy *** of mg-SiC and mg-Al_(2)O_(3)composites subjected to high energy ball milling for different vol%of secondary particles 20,30 and 40%of SiC and Al_(2)O_(3)are studied by X-Ray diffraction *** rietveld method as implemented in the Fullprof program is applied in order to determine the quantities of the resulting crystalline phases and amorphous phases at each stage of the mechanical *** examination is carried out using Scanning Electron microscope(SEm).In addition,crystal structural analysis using appropriate size and strain models is performed in order to handle the distinctive anistrophy that is observed in convinced crystallographic directions for the magnesium *** results are furnished in terms of crystalline domains size enlargement of the magnesium composites phases upon prolonged milling duration and discussed in the light of up to date views and theories on crystal growth of nanocrystaline *** hardness of the composite samples is calculated by Vickers’s Hardness ***,dry sling wear test and corrosion test are performed for the fabricated *** with 30%secondary particles incorporated magnesium composites exhibits better wear and corrosion resistance than the other composites.

关键词： Rietveld refinement X-ray diffraction Crystal structure micro structure Wear and corrosion

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High-Velocity Projectile Impact Behaviour of Friction Stir Welded AA7075 Thick Plates

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Defence Technology（防务技术） 2023年第11期29卷 153-163页

作者： R.Praveen S.R.Koteswara Rao G.selvakumar R.Damodaram Department of Robotics and Automation Karpaga Vinayaga College of Engineering and TechnologyChengalpattu603308TamilNaduIndia Department of mechanical Engineering Sri Sivasubramaniya Nadar College of EngineeringChennai603110TamilNaduIndia

In this study, high velocity impact behaviour of friction stir welded AA7075-T651 25 mm thick plates were investigated using a 7.62 mm × 51 mm lead core and 7.62 mm × 39 mm steel core projectiles. Prior to ballistic trails, mechanical and metallurgical properties of friction stir welded AA 7075-T651 25 mm thick plates were studied. microstructural and hardness studies revealed that friction stir welds constituted three distinct regions namely Weld Nugget(WN), Thermo-mechanically Affected Zone(TmAZ) and Heat Affected Zone(HAZ). Base material(Bm) and all three weld regions were ballistically tested as per military standard NIJ.0108.01 using lead and steel core bullets at maximum permissible velocities of 830 ± 20 and 700 ± 30 m/s, respectively. It has been found that base material(AA7075-T651)and all three weld regions of 25 mm thick plates were able to resist perforation by both types of projectiles used. However depth of penetration has been found to increase from Bm to WN, HAZ and TmAZ for both types of projectiles. In all cases steel core projectiles caused higher depth of penetration compared to those caused by lead core projectiles. TmAZs of the friction stir welds were found to be the weakest zone. The fracture that occurred in the base material was spall fragmentation indicating brittle failure, whereas all zones of friction stir welded AA7075-T651 targets with a front petalling, indicating ductile failure. The post-ballistic tested samples showed no significant change in the microstructure of the Bm and WN. On the other hand, TmAZ and HAZ showed severe grain deformation in the direction of projectile penetration, and the formation of adiabatic shear bands(ASB). This work showed that 25 mm thick friction stir welded AA7075-T651 joints responded well to ballistic impact loads, making them a good choice for light combat vehicles.

关键词： Aluminum alloy Thick plate Friction stir welding Ballistic performance Depth of penetration

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Ideal-Based k-Zero-Divisor Hypergraph of Commutative Rings

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Algebra Colloquium 2021年第4期28卷 655-672页

作者： K.selvakumar m.Subajini Department of mathematics Manonmaniam Sundaranar University Tirunelveli 627012Tamil NaduIndia

Let R be a commutative ring,I an ideal of R and k≥2 a fixed *** ideal-based k-zero-divisor hypergraph HkI(R)of R has vertex set ZI(R,k),the set of all ideal-based k-zero-divisors of R,and for distinct elements x1,x2,…,xk in ZI(R,k),the set{x1,x2,…,xk}is an edge in HkI(R)if and only if x1x2…xk∈I and the product of the elements of any(k-1)-subset of{x1,x2,…,xk}is not in *** this paper,we show that H3I(R)is connected with diameter at most 4 provided that x^(2)(∈)I for all ideal-based 3-zero-divisor ***,we find the chromatic number of H3(R)when R is a product of finite ***,we find some necessary conditions for a finite ring R and a nonzero ideal I of R to have H3I(R)planar.

关键词： hypergraph zero-divisor graph linear local ring k-prime ideal

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Electrochemical Impedance Spectroscopic Analysis of ZnS Nanorod Fabricated Using Butterfly Wings as Biotemplate

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Acta metallurgica Sinica(English Letters) 2015年第1期28卷 103-109页

作者： K.Jeyasubramanian m.Nisanthi V.S.Benitha N.selvakumar Centre for Nanoscience and Technology Department of Mechanical Engineering Mepco Schlenk Engineering College

This article describes the growth of zinc sulfide（ZnS） nanorod on glass/aluminum foil by employing butterfly wings as biotemplate. Upon calcinating（at 400 °C）, the butterfly wings soaked in ZnS nanoparticle suspension, with uniform cage-like nanostructures in nanodimensions, were found on glass/aluminum surface. The transverse and longitudinal dimensions of the nanorods were evaluated from scanning electron microscopy micrographs as 132 and 159 nm,respectively. Purity of the ZnS nanorod found on the specimen was checked by recording XRD（28.877°, 48.038°, and57.174°） and Fourier transform infrared spectrometer spectra（663.7 and 551.68 cm^-1）. Luminescence natures of the nanorods were examined using photoluminescence spectral studies. The characteristic emission peak is shown in the visible region with strong intensity, while the excitation peak is shown at 267 nm. Electrochemical impedance spectroscopic analysis of ZnS nanorod exhibits double-layer capacitance value（Cdl= 6.7 nF）, and the Bode plot explains the stability of ZnS nanorod under the influence of electrical field.

关键词： Semiconducting material Biotemplate Photo luminescence(PL) Nanorod Bode plot Capacitance

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Organic micro-pollutant removal in liquid-phase using carbonized silk cotton hull

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Journal of Environmental Sciences 2008年第9期20卷 1046-1054页

作者： m Sathishkumar A R Binupriya D Kavitha R selvakumar K K Sheema J G Choi Department of Food Science and Technology Institute of Agricultural Science and Technology Chonbuk National University Department of Chemical Engineering Yonsei University Department of Biotechnology Bharathiar University Department of Plant biology and Biotechnology Government Arts College National Agricultural Products Quality management Services

Phenolic compounds constitute one of the major pollutants in the modern world. Although many physical and chemical treatment technologies for their removal exist, most of them are economically not feasible. The present study was aimed at using silk cotton hull, a potent agricultural waste as an adsobent for removal of 2,4-dichlorophenol (2,4-DCP), which was used as a model phenolic compound. The process parameters were investigated and optimized conditions were determined. The equilibrium time was found to ...

关键词： silk cotton hull carbon adsorption 2 4-DCP temperature kinetic study

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Synthesis of photocatalytic La_(1–x)A_xTiO_(3.5–δ)(A=Ba, Sr, Ca) nano perovskites and their application for photocatalytic oxidation of congo red dye in aqueous solution

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Journal of Rare Earths 2015年第2期33卷 160-167页

作者： m.Bradha T.Vijayaraghavan S.P.Suriyaraj R.selvakumar Anuradha m.Ashok Nanotech Research Facility PSG Institute of Advanced StudiesCoimbatore-641 004 India Nanobiotechnology Laboratory PSG Institute of Advanced StudiesCoimbatore-641 004 India

A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites were prepared by sol-gel method and characterized using thermogravimetry/differential thermal analysis（TGA/DTA）, X-ray diffraction（XRD）, ultraviolet-visible（UV-Vis） spectroscopy and transmission electron microscopy（TEm）. XRD analysis showed that the La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites derived after calcination at 800 oC were in single phase with orthorhombic structure. The particle size of all nano perovskites was found to be ~20 nm. The synthesized nano perovskites were tested for the photocatalytic decomposition of an azo dye, Congo red. The sequential behavior of La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nanoperovskites for photocatalytic decomposition of congo red in aqueous solution by visible light at room temperature was studied at various time intervals and the efficiency of degradation of the nanoperovskites was compared. Among all the A-site substituted La0.8A0.2TiO3.5–δ（A=Ba, Sr, Ca） nano perovskites, Ba substituted compound showed the highest dye degradation.

关键词： nano perovskite oxidation photocatalyst congo red dye degradation rare earths

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Facile solvothermal synthesis of NiFe2O4 nanoparticles for high-performance supercapacitor applications

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Frontiers of materials Science 2020年第2期14卷 120-132页

作者： meenaketan SETHI U.Sandhya SHENOY selvakumar mUTHU D.Krishna BHAT Department of Chemistry National Institute of Technology KarmatakaSurathkalMangalore-575025India Department of Chemistry College of Engineering and TechnologySrinivas UniversityMukka-574146KarmatakaIndia Department of Chemistry Manipal Institute of TechnologyManipal-576104KarnatakaIndia

We report a green and facile approach for the synthesis of NiFe2O4(NF)nanoparticles with good *** prepared materials are studied by various techniques in order to know their phase structure,crystallinity,morphology and elemental *** BET analysis revealed a high surface area of 80.0 m^2·g^-1 for NF possessing a high pore volume of 0.54 cm^3·g^-1,also contributing to the amelioration of the electrochemical *** NF sample is studied for its application in supercapacitors in an aqueous 2 mol·L^-1 KOH *** properties are studied both in the three-electrode method and in a symmetrical supercapacitor *** show a high specific capacitance of 478.0 F·g^-1 from the CV curve at an applied scan rate of 5 mV·s^-1 and 368.0 F·g^-1 from the GCD analysis at a current density of 1A·g^-1 for the NF ***,the material exhibited an 88%retention of its specific capacitance after continuous 10000 cycles at a higher applied current density of8 A·g^-*** encouraging properties of NF nanoparticles suggest the practical applicability in high-performance supercapacitors.

关键词： NiFe2O4 nanoparticle solvothermal method BET surface area specific capacitance supercapacitor

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Neuroendocrine carcinoma of the ampulla of Vater:a clinicopathologic evaluation

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Hepatobiliary & Pancreatic Diseases International 2008年第4期7卷 422-425页

作者： Eswaran selvakumar Shanmugasundaram Rajendran Tirupporur Govindaswamy Balachandar Devy Gounder Kannan Satyanesan Jeswanth Palaniappan Ravichandran Rajagopal Surendran Department of Surgical Gastroenterology Center for G.I.Bleeding & Division of Hepatobiliary Pancreatic Diseases Government Stanley Medical College Hospitalthe Tamilnadu Dr. M.G.R.Medical UniversityChennai 600001TamilnaduIndia

BACKGROUND:Only 105 cases of neuroendocrine tumor(NET)of the ampulla of Vater have been described, mostly as single case *** incidence of NET is *** changes in incidence may result from changes in *** study was to determine the relative incidence and clinicopathological characteristics of high- grade neuroendocrine carcinoma(small cell carcinoma and large cell carcinoma)of the ampulla of Vater at a single institution. mETHODS:Sections from paraffin blocks of tumors of the ampulla of Vater taken from 45 patients who underwent Whipple’s procedure and 6 patients who underwent palliative bypass between September 2003 and January 2007 were subjected to immunohistochemical *** clinical and pathological data from 5 patients diagnosed with NET of the ampulla of Vater were analyzed. RESULTS:The patients were 3 men and 2 women,ranging in age from 39 to 47 years(mean 44 years).Operative procedures included Whipple’s procedure in 4 patients and palliative bypass in 1 *** examination revealed large-cell neuroendocrine carcinoma in 2 patients,small cell carcinoma in 2,and carcinoid in *** patients with high-grade neuroendocrine carcinoma who had undergone Whipple’s procedure died at postoperatively 7,11,and 13 *** patient who had undergone palliative triple bypass died 3 months after ***:The relative incidence of high-grade neuroendocrine carcinomas of the ampulla of Vater is higher than that generally *** tumors behave aggressively and have a dismal prognosis despite aggressive treatment.

关键词： neuroendocrine tumor carcinoid tumor ampulla of Vater Whipple's procedure

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Long-term outcome of gastric access loop in hepaticojejunostomy

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Hepatobiliary & Pancreatic Diseases International 2008年第2期7卷 152-155页

作者： Eswaran selvakumar Shanmugasundaram Rajendran Tirupporur G. Balachandar Devy Gounder Kannan Satyanesan Jeswanth Palaniappan Ravichandran Rajagopal Surendran Department of Surgical Gastroenterology Center for G.I.Bleed & Division of Hepatobiliary Pancreatic Diseases Government Stanley Medical College Hospital The Tamilnadu Dr. M.G.R. Medical University Chennai-600001 Tamilnadu India

BACKGROUND:?The incidence of hepaticojejunostomy stricture is 4%-10% in experienced centres. many access loops have been designed and used to facilitate endoscopic intervention for this complication of hepaticojejunostomy. In this study, we investigated the effectiveness and safety of gastric access loop. mETHODS:A retrospective analysis was conducted on 13 patients who had undergone hepaticojejunostomy with gastric access loop between June 1999 and September 2003. Eleven patients were followed up for a mean period of 51 months (range 20-81 months). Two patients were lost to follow up. RESULTS:?On follow-up, 8 patients had patent jejuno- gastrostomy (end to side anastomosis between Roux loop of jejunum and stomach) and hepaticojejunostomy. Three patients developed stricture of jejunogastrostomy at 41 months, 63 months and 81 months of follow-up. Among these 3 patients, one also had hepaticojejunostomy stricture. In the patient with hepaticojejunostomy stricture, dilatation of jejunogastrostomy stricture was attempted but failed. None of the patients had any evidence of bile gastritis/cholangitis. There was no procedure related morbidity/mortality. CONCLUSIONS:Further studies involving large numbers of patients are required before wide application of gastric access loop in hepaticojejunostomy though it is a safer option than percutaneous transhepatic manipulations or revision surgery.

关键词： access loop hepaticojejunostomy anastomotic stricture biliary stricture

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Large cell neuroendocrine carcinoma of the ampulla of Vater

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Hepatobiliary & Pancreatic Diseases International 2006年第3期5卷 465-467页

作者： Eswaran selvakumar Velayutham Vimalraj Shanmugasundaram Rajendran Tirupporur G.Balachandar Devy G.Kannan Satyanesan Jeswanth Palaniappan Ravichandran Arunachalam Sundaram Rajagopal Surendran Departments of Pathology and Surgical Gastroenterology Center for G.I.Bleeding & Division of Hepatobiliary Pancreatic Diseases Government Stanley Medical College Hospitalthe Tamilnadu Dr.M.G.R.Medical UniversityChennaiTamilnaduIndia

BACKGROUND: Neuroendocrine tumors of the ampulla of Vater are extremely rare, and few cases of large cell neuroendocrine carcinoma (LCNEC) of the ampulla have been reported. mETHODS: A 48-year-old male with obstructive jaundice was admitted to our hospital. On examination the patient was found to have a periampullary growth and subsequently underwent the Whipple's procedure. RESULTS: Histopathological examination and immunohistochemistry revealed features of LCNEC of the ampulla of Vater. The patient developed multiple liver metastases 6 months after Whipple's procedure. CONCLUSION: LCNEC of the ampulla of Vater is rare and highly aggressive, with a dismal prognosis.

关键词： large cell neuroendocrine carcinoma ampulla of Vater Whipple's procedure periampullary growth

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