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In vitro antioxidant activities of ethanol extract from Enhalus acoroides (L.F.) Royle

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Asian Pacific Journal of Tropical Medicine 2010年第11期3卷 898-901页

作者： Rengasamy Ragupathi Raja Kannan rajasekaran arumugam Perumal Anantharaman CAS in Marine Biology Faculty of Marine SciencesAnnamalai UniversityParangipettai-608 502India

Objective:To search for new sources of safe and inexpensive antioxidants,the leaf,root and rhizome of Enhalus acoroides(***) were screened for the first time for their antioxidant ***:Samples of leaf,root and rhizome from *** were tested for total phenolic content,proanthocyanidins and in vitro antioxidant activity in terms of total antioxidant assay,DPPH assay and FRAP ***:The leaf sample was found to have high levels of phenolic(0.323±0.028 mg TAE/g) and proanthocyanidins(0.570 0±0.000 3 mg TAE/g) when compared to root and *** leaf samples exhibited higher total antioxidant activity (11.770±0.026 mg Ascorbic acid equivalent/g),higher percentage of DPPH radical scavenging activity(25.76±0.04) and higher reducing power(18.060±0.073) in terms of mg GAE/*** addition, there was a significant correlation between total phenolic content and total antioxidant activity (R^2=0.923),DPPH assay(R^2=0.509).FRAP assay(R^2=0.994).Similarly,significant correlation was found between the proanthocyanidin and total antioxidant activity(R^2=0.977),DPPH assay (R^2=0.464) and the FRAP assay(R^2=0.998).Conclusions:These results suggested that *** have strong antioxidant *** study is necessary for isolation and characterization of the active antioxidant agents,which can be used to treat various oxidative stress-related diseases.

关键词： Enhalus acoroides Antioxidant activity Phenolic content DPPH(2,2-Diphenyl-1-picrylhydrazyl) FRAP assay

A novel manganese tungstate nanorod catalyst for the oxidation of styrene with tert-butyl hydroperoxide as oxidant

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Tungsten 2024年第4期6卷 845-858页

作者： Shanmugam Manimaran arumugam Pandurangan Gopalakrishnan Govindasamy Department of Chemistry Anna University Energy Cluster School of Engineering University of Petroleum and Energy Studies (UPES)

Catalyst,solvent and process parameters are the keys for the selective oxidation of styrene and other olefins to value added *** MnWO4was synthesized by the one-pot hydrothermal method using Pluronic F127 as a surfactant,characterized and evaluated for the oxidation of styrene and different olefins,using tert-butyl hydroperoxide（TBHP） as oxidant.X-ray diffractogram confirmed the phase purity of MnWO4which became further evident from the near surface equimolar proposition of Mn and W in+2 and+6 oxidation states,respectively,as inferred from X-ray photoelectron spectra.N2sorption followed type Ⅳa isotherm with H3 hysteresis loop,starting at the relative pressure（P/P_o） of 0.9,typically of mesoporous materials containing macropores as further confirmed by pore-size *** electron microscope images of MnWO4revealed its nanorod *** the absence of catalyst,styrene conversion was 35%with benzaldehyde as the sole product and addition of 75 g of MnWO4increased the styrene conversion to 97.3%,and the styrene oxide selectivity from 0% to 85% demonstrated its activity and *** the maximum conversion and styrene oxide selectivity optimum temperature,styrene:TBHP molar ratio,catalyst amount and solvent were found to be 70 ℃,1:2,75 mg,and acetonitrile,***4catalyst retained its activity and selectivity for five recycles,confirming its recoverability and *** the kinetic studies,pre-exponential factor and apparent activation energy were found to be 0.206 s-1and 31.5 kJ·mol-1,respectively,and a reaction mechanism was ***4catalyst was active for oxidation of alkenes,cycloolefins and alkenyl aromatics with high selectivity for epoxides.

关键词： Epoxidation Manganese tungstate nanorod Styrene oxidation

Annealing-induced long-range charge density wave order in magnetic kagome FeGe:Fluctuations and disordered structure

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 112-121页

作者： Chenfei Shi Yi Liu Bishal Baran Maity Qi Wang Surya Rohith Kotla Sitaram Ramakrishnan Claudio Eisele Harshit Agarwal Leila Noohinejad Qian Tao Baojuan Kang Zhefeng Lou Xiaohui Yang Yanpeng Qi Xiao Lin Zhu-An Xu arumugam Thamizhavel Guang-Han Cao Sander Van Smaalen Shixun Cao Jin-Ke Bao Department of Physics Materials Genome InstituteInstitute for Quantum Science and TechnologyShanghai UniversityShanghai 200444China Key Laboratory of Quantum Precision Measurement of Zhejiang Province School of PhysicsZhejiang University of TechnologyHangzhou 310023China School of Physics Zhejiang UniversityHangzhou 310027China Department of Condensed Matter Physics and Materials Science Tata Institute of Fundamental ResearchMumbai 400005India School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China ShanghaiTech Laboratory for Topological Physics ShanghaiTech UniversityShanghai 201210China Laboratory of Crystallography University of BayreuthBayreuth 95447Germany Department of Quantum Matter AdSEHiroshima UniversityHigashi-Hiroshima 739-8530Japan P24 PETRA IIIDeutsches Elektronen-Synchrotron DESYHamburg 22607Germany Key Laboratory for Quantum Materials of Zhejiang Province School of ScienceWestlake UniversityHangzhou 310024China Department of Physics China Jiliang UniversityHangzhou 310018China Shanghai Key Laboratory of High-resolution Electron Microscopy ShanghaiTech UniversityShanghai 201210China Collaborative Innovation Centre of Advanced Microstructures Nanjing UniversityNanjing 210093China Shanghai Key Laboratory of High Temperature Superconductors Shanghai UniversityShanghai 200444China School of Physics Hangzhou Normal UniversityHangzhou 311121China

Charge density wave(CDW) in kagome materials with the geometric frustration is able to carry unconventional ***, a CDW has been observed below the antiferromagnetic order in kagome FeGe, in which magnetism and CDW are intertwined to form an emergent quantum ground state. However, the CDW is only short-ranged and the structural modulation originating from it has yet to be determined experimentally. Here we realize a long-range CDW order by post-annealing process,and resolve the structure model through single crystal X-ray diffraction. Occupational disorder of Ge resulting from short-range CDW correlations above T_(CDW) is identified from structure refinements. The partial dimerization of Ge along the c axis is unveiled to be the dominant distortion for the CDW. Occupational disorder of Ge is also proved to exist in the CDW phase due to the random selection of partially dimerized Ge sites. Our work provides useful insights for understanding the unconventional nature of the CDW in FeGe.

关键词： charge density wave kagome disordered structure fluctuations

2,5-Dimercapto-1,3,4-Thiadiazole(DMCT)-Based Polymers for Rechargeable Metal-Sulfur Batteries

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Energy & Environmental Materials 2023年第6期6卷 283-290页

作者： Amruth Bhargav arumugam Manthiram Materials Science and Engineering Program&Texas Materials Institute The University of Texas at AustinAustin Texas 78712USA

Organosulfur materials are a sustainable alternative to the present-day layered oxide cathodes in lithium-based *** such organosulfur material that was intensely explored from the 1990s to early 2010s is 2,5-dimercapto-1,3,4-thiadiazole(DMCT).However,research interest declined as the electrode reactions with DMCT were assumed to be too sluggish to be *** with the advances in metal-sulfur batteries,we revisit DMCT-based materials in the form of poly[tetrathio-2,5-(1,3,4-thiadiazole)],referred to as *** an appropriate choice of electrode design and electrolyte,pDMCT-S cathode paired with a Li-metal anode shows a capacity of 715 mA h g^(-1)and a Coulombic efficiency of 97.7%at a C/10 rate,thus quelling the concerns of sluggish ***,pDMCT-S shows significantly improved long-term cyclability compared to a sulfur *** into the origin of the stability reveals that the discharge product Li-DMCT in its mesomeric form can strongly bind to polysulfides,preventing their dissolution into the electrolyte and *** unique mechanism solves a critical problem faced by sulfur ***,this mechanism results in a stable performance of pDMCT-S with Na-metal cells as *** study opens the potential for exploring other organic materials that have inherent polysulfide sequestering capabilities,enabling long-life metal-sulfur batteries.

关键词： 2,5-dimercapto-1,3,4-thiadiazole electrochemistry metal-sulfur batteries organopolysulfide organosulfur batteries

Growth response of Pterocarpus santalinus seedlings to native microbial symbionts(arbuscular mycorrhizal fungi and Rhizobium aegyptiacum)under nursery conditions

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Journal of Forestry Research 2021年第1期32卷 225-231页

作者： arumugam Karthikeyan Thangavel Arunprasad Institute of Forest Genetics and Tree Breeding Coimbatore 641002India

The objective of this research was to improve the growth and biomass of Pterocarpus santalinus L.f.(an endangered leguminous tree)using native microbial symbionts such as arbuscular mycorrhizal fungi and Rhizobium associated with native populations of *** native arbuscular mycorrhizal fungi isolated from *** soils were identifi ed as(1)Glomus fasciculatum;(2)Glomus geosporum;and Glomus aggregatum.A nitrogenfi xing microbial symbiont was isolated from the root nodules of *** and identifi ed as Rhizobium aegyptiacum by 16s rRNA gene *** microbial symbionts were inoculated individually and in combination into *** seedling *** 90 days,growth and biomass had improved compared with uninoculated *** and root lengths,number of leaves,stem circumference,number of root nodules,biomass,nutrient uptake and seedling quality index were signifi cantly increased by a combined inoculation of arbuscular mycorrhizal fungi+Rhizobium *** was concluded that native microbial symbionts positively infl uenced *** seedling growth which will be helpful for successful fi eld establishment.

关键词： Arbuscular mycorrhizal fungi Microbial symbionts Pterocarpus santalinus Red sanders Rhizobium aegyptiacum

Scalable Membraneless Direct Liquid Fuel Cells Based on a Catalyst-Selective Strategy

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Energy & Environmental Materials 2018年第1期1卷 13-19页

作者： Xingwen Yu arumugam Manthiram Materials Science&Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX 78712USA

This perspective presents a membraneless direct liquid fuel cell(DLFC)concept based on a catalyst-selective *** membraneless DLFCs are operated at low temperatures by employing a non-precious cathode catalyst with a high catalytic *** uniqueness is that the inexpensive cathode catalyst only catalyzes the oxygen reduction reaction but does not catalyze the oxidation reaction of a specific ***,during the operation of DLFCs,the liquid fuel can enter the cathode freely without any concern of fuel *** catalyst-selective approach tactfully avoids the use of high-cost or technically unviable ion-exchange polymer membranes in *** catalyst-selective operating principle also overcomes the scalability issue of the traditional laminar-flow membraneless *** a proper management of the anode and cathode catalysts in the cell,a variety of inexpensive,renewable alcohols,and small-molecule organics can be employed as anode *** innovative approach of membraneless alkaline DLFCs offers a great opportunity for the development of inexpensive energy-generation systems for both mobile and stationary *** addition to summarizing the principle and the research progress of the unique membraneless DLFC platform,the challenges and future research directions are presented.

关键词： catalyst uniqueness overcome

Transient Behavior of a Single-Server Markovian Queue with Balking and Working Vacation Interruptions

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Journal of the Operations Research Society of China 2021年第2期9卷 321-341页

作者： arumugam Azhagappan Thirunavukkarasu Deepa Department of Mathematics St.Anne’s College of Engineering and TechnologyAnna UniversityPanrutiTamilnadu 607110India Department of Mathematics Idhaya College of Arts and Science for WomenPondicherry UniversityPakkamudayanpetPuducherry 605008India

This paper studies the time-dependent analysis of an M/M/1 queueing model with single,multiple working vacation,balking and vacation *** the system becomes empty,the server commences working *** the working vacation period,if the queue length reaches a positive threshold value‘k’,the working vacation of the server is interrupted and it immediately starts the service in an exhaustive *** working vacations,the customers become discouraged due to the slow service and possess balking *** transient system size probabilities of the proposed model are derived explicitly using the method of generating function and continued *** performance indices such as average and variance of system size are also ***,numerical simulations are presented to analyze the impact of system parameters.

关键词： The M/M/1 queue Single and multiple working vacation Balking Vacation interruption Continued fractions Transient probabilities

Towards the low temperature growth of uniform diameter multi walled carbon nanotubes by catalytic chemical vapour deposition technique

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Nano-Micro Letters 2010年第3期2卷 204-212页

作者： Thirunavukkarasu Somanathan arumugam Pandurangan Department of Chemistry Anna University Chennai Department of Chemical Engineering University of Massachusetts

Mesoporous MCM-41 molecular sieves containing f-block transition elements（gadolinium） with various Si/Gd ratios（50,75 and 100） were synthesised by a hydrothermal *** mesoporous structure was confirmed by X-ray diffraction,nitrogen sorption studies,thermogravimetric analysis,scanning and transmission electron *** local environment of Gd in the material was studied by electron paramagnetic *** compatibility of the catalyst for the synthesis of uniform diameter CNTs by varying the temperature from 400 to 650°C with fixed flow rates of N2 and C2H2（140 ml/min and 40 ml/min,respectively）.The product is mostly metal containing thin MWCNTs with diameter of 1020 *** shows that a combination of Gd-MCM-41（100） catalyst gives a high yield of high quality MWCNTs under optimum growth conditions.

关键词： MWCNTs Gd carbon nanotubes Contrasting agents Magnetic resonance imaging

Responses of Bruguiera sexangula propagules to beneficial microbes in the nursery

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Journal of Forestry Research 2018年第4期29卷 1082-1087页

作者： arumugam Karthikeyan Natchimuthu Balasubramaniam Sivapriya Institute of Forest Genetics and Tree Breeding Coimbatore 641002 India

Bruguiera sexangula （Lout） Poir., a threatened mangrove tree, was inoculated with beneficial microbes in a nursery to assess any improvements in growth and bio- mass. From soil samples from the rhizosphere of B. sexangula in a mangrove forest in Panangadu of Kerala India, nitrogen-fixing bacteria Azotobacter chroococcum and Azospirillum brasilense were isolated. The phosphatesolubilising bacterium Bacillus megaterium and potassiummobilizing bacteria Frateruria aurantia were also isolated and cultured on suitable media. Later, ripe propagules of B. sexangula were collected from matured trees and raised in sterilized soil bags （13 × 25 cm） containing sterilized soil and sand （2：1 ratio）. The cultured beneficial microbes were propagated and used to inoculate the ripe propagules of B. sexangula and maintained in the nursery for 6 months. After 6 months, growth and biomass of the inoculated propagules were greater than for the uninoculated control propagules. Shoot length, number of leaves, stem girth and root length were also significantly greater than in the controls. This study showed that the mangrove-specific beneficial microbes influenced the growth of B. sexangula

关键词： Mangroves Bruguiera sexangula Beneficial microbes Nursery Propagules