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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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Episodic dolomitization of Paleozoic limestones in the Kinta Valley,Malaysia:Implications on porosity evolution and reservoir properties

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Energy Geoscience 2021年第4期2卷 298-307页

作者： Poon Xin Hui Mu.ramkumar R.Nagarajan Manoj J.Mathew t.F.Ng South East Asia Carbonate Research Laboratory(SEACaRL) Universiti Teknologi PETRONASBandar Seri Iskandar31750TronohPerakMalaysia Department of Geology Periyar University636011SalemIndia Department of Applied Geology Curtin UniversityMalaysia98009MiriSarawakMalaysia Shale Gas Research Group Institute of Hydrocarbon RecoveryUniversiti Teknologi PETRONAS31750TronohPerakMalaysia Department of Geology University of MalayaKuala LumpurMalaysia

Carbonates undergo a variety of physical,mineralogical,chemical changes during depositional and postdepositional stages that are of interest to exploration geologists and *** over,about 60%of hydrocarbon reserves occur in carbonates with the dominant proportion associated with dolomitic reservoirs,in particular fault-associated dolomites which appear to be proven hydrocarbon *** as the critical diagenetic process thus plays an important role in determining reservoir characteristics and in designing exploration *** buried Paleozoic dolomites exhibit relatively higher porosity than their counterparts,Paleozoic ***-associated dolomites are usually targets of hydrocarbon exploration due to their good reservoir *** heterogeneity in carbonate reservoirs due to varied porosity types and distribution makes reservoir characterization a daunting ***,the key elements that control porosity development and evolution in these dolomites remain *** the influence of multiphase dolomitization,associated diagenetic events,hydrothermal alteration and their causative thermo-tectonic events on porosity evolution and reservoir quality is essential to understanding the critical processes and controlling factors that result in diverse impacts on reservoir *** this paper,an attempt is made to characterize dolomitization in homogeneous carbonate mud and its relationship with porosity evolution and reservoir *** the field,six facies types excluding host limestone are recognized,which are in turn characterized into seven petrographically recognizable phases,namely the host limestone,early replacement dolomite,sucrosic dolomite,metamorphosed dolomite,late replacement dolomite,brecciated limestone and dolomite and late stage *** analyses reveal the dominance of stoichiometric dolomites,followed by calcareous dolomites and magnesium *** all the field-based f

关键词： Dolomitization Porosity evolution Paleozoic Kinta Valley Malaysia

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Feasibility and clinical outcomes in nonagenarians undergoing transcatheter aortic valve replacement with the LOtUStM valve

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Journal of Geriatric Cardiology 2016年第7期13卷 636-638页

作者： Satish ramkumar Hashrul N Rashid Sarah Zaman Liam McCormick Robert Gooley Damon Jackson Ian t Meredith MonashHEARt Monash Health Melbourne Victoria Australia Monash Cardiovascular Research Centre Monash University Melbourne Victoria Australia

Surgical aortic valve replacement （AVR） is associated with very high peri-operative risk in the nonagenarian populationflI Patients with severe aortic stenosis treated conservatively have high rates of mortality with poor quality of life and loss of independence. transcatheter aortic valve replacement （tAVR） has been validated in the high risk elderly population as a viable alternative to surgery with comparable outcomes.

关键词： Aortic valve replacement Nonagenarian patients transcatheter aortic valve replacement

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Design and Development of an Intelligent Energy Management System for a Smart Grid to Enhance the Power Quality

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Energy Engineering 2023年第8期120卷 1747-1761页

作者： Nisha Vasudevan Vasudevan Venkatraman A.ramkumar t.Muthukumar A.Sheela M.Vetrivel R.J.Vijaya Saraswathi F.t.Josh Department of Electrical and Electronics Engineering Kalasalingam Academy of Research and EducationTamil NaduIndia Department of Computer Science Engineering Kalasalingam Academy of Research and EducationTamil NaduIndia Department of Electrical and Electronics Engineering Kongunadu College of Engineering and TechnologyTamil NaduIndia Department of Electrical and Electronics Engineering Kongu Engineering CollegeTamil NaduIndia Department of Electrical and Electronics Engineering Narasu’s Sarathy Institute of TechnologyTamil NaduIndia Department of Electrical and Electronics Engineering Panimalar Engineering CollegeTamil NaduIndia Department of Electrical and Electronics Engineering Karunya Institute of Technology&SciencesTamil NaduIndia

MigroGrid(MG)has emerged to resolve the growing demand for *** because of its inconsistent output,it can result in various power quality(PQ)*** is a problem that is becoming more and more important for the reliability of power systems that use renewable energy ***,the employment of nonlinear loads will introduce harmonics into the system and,as a result,cause distortions in the current and voltage waveforms as well as low power quality issues in the supply ***,this research focuses on power quality enhancement in the MG using hybrid shunt ***,the performance of the filter mainly depends upon the design,and stability of the *** efficiency of the proposed filter is enhanced by incorporating an enhanced adaptive fuzzy neural network(AFNN)*** performance of the proposed topology is examined in a MAtLAB/Simulink environment,and experimental findings are provided to validate the effectiveness of this ***,the results of the proposed controller are compared with Adaptive Fuzzy Back-Stepping(AFBS)and Adaptive Fuzzy Sliding(AFS)to prove its superiority over power quality improvement in *** the analysis,it can be observed that the proposed system reduces the total harmonic distortion by about 1.8%,which is less than the acceptable limit standard.

关键词： Artificial intelligence resistive inductive load shunt hybrid filter smart grid adaptive fuzzy back-stepping power factor

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High Ba-Sr adakitic charnockite suite from the Nagercoil Block,southern India:Vestiges of Paleoproterozoic arc and implications for Columbia to Gondwana

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Geoscience Frontiers 2021年第3期12卷 577-596页

作者： Pin Gao M.Santosh Cheng-Xue Yang Sanghoon Kwon Mu.ramkumar School of Earth Sciences and Resources China University of Geosciences(Beijing)29 Xueyuan RoadBeijing 100083PR China Department of Earth Sciences University of AdelaideAdelaideSA 5005Australia Department of Earth Sciences Yonsei UniversitySeoul 03772Republic of Korea Department of Geology Periyar UniversitySalem 636011India

the Nagercoil block is the southernmost crustal segment of the Southern Granulite terrane(SGt)in India and is mainly composed of charnockitic rocks and felsic gneisses(charnockite suite).In this study,we present petrologic,geochemical,zircon U-Pb,REE,and Hf isotopic studies on the charnockites and leucogneiss from the Nagercoil *** on field investigations and petrologic studies,the charnockites can be divided into garnet-bearing and garnet-absent anhydrous granulite facies rocks with *** charnockites and leucogneiss show transition from adakites to non-adakitic magmatic rocks,with enrichment in LREEs(light rare earth elements)and LILEs(large ion lithophile elements),and depletion in HREEs(heavy rare earth elements)and HFSEs(high field strength elements).Some of the charnockites and the leucogneiss show typical HSA(high silica adakite)characters,(high SiO_(2),Al_(2)O_(3),Ba-Sr,La/Yb,and Sr/Y).the HSA is considered to have formed from the interaction of slab derived melts and peridotitic mantle *** high Ba-Sr features were possibly inherited from subducted oceanic crust melting under high thermal gradient during *** magmas were underplated and subjected to fractional *** grains from the charnockite and leucogneiss show zoned magmatic cores surrounded by structureless metamorphic *** zircon grains from the charnockites show ages ranging from 1983±8.8 Ma to 2046±14 Ma,and the metamorphic domains show an age range of 502±14 Ma to 547±8.7 *** from the leucogneiss yielded magmatic and metamorphic ages of 1860±20 Ma and 575.6±8.8 *** charnockites and leucogneiss show two prominent age peaks at 1987 Ma and 568 *** REE data of the zircon grains show LREE depletion and HREE enrichment,with the metamorphic grains showing more depletion in *** Hf isotopic data of the magmatic cores of zircon grains from the charnockite yieldedε_(Hf)(t)values from-1.17 to 0.46 with t_(DM)and t_(DM)~C and age

关键词： Charnockite Adakitic rocks High Ba-Sr granitoids Geochemistry and zircon geochronology Nagercoil block Columbia and Gondwana supercontinents

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Evaluation of geochemical behavior and heavy metal distribution of sediments:the case study of the tirumalairajan river estuary,southeast coast of India

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International Journal of Sediment Research 2015年第1期30卷 28-38页

作者： Senapathi VENKAtRAMANAN Sang-yong CHUNG thirunavukkarasu ramkumar Gopalakrishnan GNANACHANDRASAMY tae Hyung KIM Department of Earth & Environmental Sciences Institute of Environmental GeosciencesPukyong National University Department of Earth Sciences Annamalai University K-Water Institute Korea Water Resources Corporation

the purpose of this study was to assess the chemical partitioning of selected heavy metals(Fe,Mn,Cu,Zn,Pb,Cr,Co and Ni) in 10 surface sediments at tirumalairajan River Estuary in the southeastern coast of India.A five-step sequential extraction technique was used to assess the environmental status of heavy *** of metals were considered to be immobile due to the high availability in the residual fraction of heavy *** sediments of tirumalairajan River estuary had not been polluted by heavy metals,and they didn’t pose any high ecological *** seasonal variations of heavy metals were slightly higher in summer than in monsoon *** analysis was also carned out to understand the associations of metals in different fractions with sand,silt,clay,organic matter,pH,salinity and other *** relationship between the Q-mode and R-mode cluster analyses was useful for identifying the pollution levels in both *** was proved that the enrichment of heavy metals was related with geogenic and anthropogenic *** information on total metal concentrations in sediments was not sufficient for assessing the metal behavior in the environment,but the sequential extraction technique was more effective in estimating the environmental impact of contaminated sediments.

关键词： Five-step sequential extraction Factor analyses Q-mode and R-mode cluster analysis Heavy metals tiurmalairajan estuary

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Oxidative stress and breast cancer biomarkers:the case of the cytochrome P450 2E1

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Journal of Cancer Metastasis and treatment 2016年第1期2卷 268-276页

作者： Subir Singh ramkumar Rajendran Kengo Kuroda Emiko Isogai Marija Krstic-Demonacos Constantinos Demonacos Manchester Pharmacy School University of ManchesterManchester M139PTUK School of Pharmacy International Medical UniversityBukit Jalil57000 Kuala LumpurMalaysia Laboratory of Animal Microbiology Tohoku University Graduate School of Agricultural ScienceSendaiMiyagi981-8555Japan School of Environment and Life Sciences University of SalfordPeel BuildingSalfordM54WTUK

Aim:the aim of the study is to investigate the impact of the cytochrome P4502E1,which is the most efficient CYP450 family member in generating reactive oxygen species(ROS),on cellular energy metabolism of breast cancer cells and therefore the effects of CYP2E1 on breast ***:the estrogen receptor positive MCF-7 and the triple negative MDA-MB-231 breast cancer cells were used as experimental system to estimate ROS generation in these cells overexpressing CYP2E1 and treated with the glycolytic inhibitors 3-bromopyruvate or 2-deoxyglucose in the presence or absence of the CYP2E1 inhibitor *** triphosphate(AtP)assay was used to measure AtP production and lactate assay to quantify the efflux of lactic acid in breast cancer cells treated with the CYP2E1 inhibitor chlormethiazole,the mitochondrial membrane potential and cell viability assays were employed to assess the pathway of cellular energy production and cellular death respectively after treatment of MCF-7 and MDA-MB-231 with the CYP2E1 activator acetaminophen or the CYP2E1 inhibitor ***:t he r esults i ndicated i ncreased ROS generation i n b reast c ancer c ells overexpressing C *** generation was differentially regulated in breast cancer cells upon treatment with the CYP2E1 inhibitor *** treated MCF-7 cells exhibited reduced lactate efflux implying that CYP2E1 directly or indirectly regulates the glycolytic rate in these *** the mitochondrial membrane potential of both MCF-7 and MDA-MB-231 cells was differentially affected by the CYP2E1 activator acetaminophen versus the CYP2E1 inhibitor chlormethiazole providing additional support for the involvement of CYP2E1 in energy metabolic pathways in breast ***:Results presented in this study provide evidence to suggest that CYP2E1 regulates cellular energy metabolism of breast cancer cells in a manner dependent on cell type and potentially on the clin

关键词： Reactive oxygen species cytochrome P4502E1 glycolysis breast cancer

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结肠直肠癌术后POSSUM、P-POSSUM及结肠直肠POSSUM预测术后病死率的比较

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世界核心医学期刊文摘（胃肠病学分册） 2006年第9期2卷 17-17页

作者： ramkumar t. Ng V. Fowler L. Farouk R. 郑世成 Department of Surgery Royal Berkshire HospitalReadingRG1 5ANUnited Kingdom

PURPOSE:POSSUM(Physiologic and Operative Severity Score for enumeration of Morbidity &Mortality)and P-POSSUM have been validated as scoring tools for the prediction of postoperative complications in general surgical *** recently a colorectal-specific POSSUM has been developed for mortality *** study was designed to evaluate and compare the accuracy for mortality prediction of POSSUM,P-POSSUM,and colorectal POSSUM after major and complex major colorectal ***:the relationship between the observed and expected morbidity and mortality was examined in 347 consecutive patients(321 elective,26 urgent)undergoing amajor or complex major colorectal resection using POSSUM,P-POSSUM,and Colorectal *** accuracy of using these scoring tools to predict mortality was assessed using Receiver Operator Characteristic curve ***:A total of 347 consecutive patients(median age,69(range,34-92)years)were ***-one patients(20.5 percent)suffered a postoperative complication and 15 patients(4.3 percent)*** observed∶expected POSSUM ratio for morbidity was 0.71 and mortality *** area under curve from Receiver Operator Characteristic curve analysis for POSSUM was *** observed∶expected mortality ratio for P-POSSUM was 0.71,and the area under curve from Receiver Operator Characteristic curve analysis was *** observed∶expected mortality ratio for colorectal POSSUM was 0.75,and the area under the curve from Receiver Operator Characteristic curve analysis was ***:Colorectal POSSUM provides comparable prediction of mortality risk after colorectal resection compared with POSSUM and P-POSSUM.

关键词： POSSUM评分结肠直肠切除术术后病死率直肠癌术后预测受试者操作特征曲线严重度评分择期手术

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