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- 저자 : K.M. Ramkumar (검색결과 5 건)
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S. Sivasankaran,K. R. Ramkumar,Fahad A. Al‑Mufadi,Osama M. Irfan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
Al 7075 alloy matrix reinforced with different weight percentage of titanium borides (TiB2, 0, 1.5, 3, 4.5 and 6 wt%) and1 wt% graphite (Gr) hybrid composites were synthesized by in-situ liquid metallurgy route, then the sliding wear characteristicswere performed and investigated in this research work. TiB2reinforced as 0, 1.5, 3, 4.5 and 6 wt% by the in situchemical reaction of KBF4and K2TiF6salts and 1 wt% Gr with the Al 7075 matrix were added constantly in the melt. Severalexperiments were carried out to examine the wear behavior of the fabricated composite specimens through a tribometer atambient temperature. The weight percentage of reinforcement (TiB2 particles), the applied load, the sliding velocity (SV),and the sliding distance (SD) were selected as process parameters at five different levels. The response surface methodology(RSM) was used to conduct the experiments as RSM is the feasible and accurate method employed for optimizing to set theparameters. To check the significance of the developed model by RSM, ANOVA and confirmatory tests were also accomplished. FESEM surface morphology was also carried out to illustrate the uniform dispersion of the TiB2–Gr particulatesin Al 7075 matrix. The predicted wear characteristics from the developed model were well agreed with the experimentalresults. The obtained results were explained that both the increase in the percentage of RF and SV have dropped the wearloss (WL) curve whereas the load at all SVs and the SDs were uplifted the WL. The worn surface morphology explainedthat the adhesive mechanisms were dominated during the sliding wear test. Further, severe and mild wear occurred duringhigher load and lower load respectively.
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K. Navaneetha Pandiyaraj,A. Arun Kumar,M.C. RamKumar,K. Thirupugalmani,Avi Bendavid,Pi-Guey Su,S. Uday Kumar,P. Gopinath 한국물리학회 2016 Current Applied Physics Vol.16 No.7
In the present investigation, we have studied the influence of oxygen (O2) flow rate in the atmospheric pressure argon (Ar) plasma zone for improvement of the surface and cell compatible properties of LDPE film. Various characterization techniques such as contact angle (CA), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), etc were used to investigate the hydrophilicity, surface chemistry and morphology of LDPE films respectively. Fowke's approximation method was used to evaluate the polar and dispersion components of the total surface energy of LDPE films using contact angle values of three testing liquids. Moreover T-peel and lap shear tests were used to analyze the adhesive strength of the surface modified LDPE films. Finally cyto-compatibility of the surface modified LDPE film was analyzed by in vitro cell compatibility analysis which includes the cell viability and adhesion using NIH-3T3 fibroblast cells. The results obtained from various characterization techniques evidently revealed that cold atmospheric pressure (CAP) plasma treatment enhanced the surface properties (hydrophilicity, surface morphology and surface chemistry) of LDPE film. Owing to tailored physico-chemical changes induced by the CAP plasma treatment facilitates improvement in adhesive strength as well as adhesion and proliferation of cells on the surface of LDPE films.
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K. Navaneetha Pandiyaraj,D. Vasu,A. Raji,Rouba Ghobeira,Parinaz Saadat Esbah Tabaei,Nathalie De Geyter,Rino Morent,M.C. Ramkumar,M. Pichumani,R.R. Deshmukh 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.122 No.-
The current study investigates the combinatorial effect of the photocatalytic performance of plasma pretreatedTi-Cu-Zn doped graphene oxide (TCZ-GO) nanoparticles (NPs) and advanced oxidation processesof a non-thermal atmospheric pressure plasma on the degradation of reactive orange-122 (RO-122) dyecompounds. Firstly, in order to enhance the photocatalytic performance of the synthesized compositeNPs, they were subjected to glow discharge plasma treatments operating in different gases (Ar, air, O2and N2). Their surface morphology, chemical composition and band gap were examined by means ofscanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV–Vis spectrophotometryrespectively. XPS results revealed that plasma-treated NPs exhibited a higher content of oxygenvacancies and a variation in their oxidation states (Ti4+?Ti3+, Cu+?Cu2+). These plasma-induced surfacechemical changes hindered the recombination of photo-generated electron-hole pairs which led to a dropin the bandgap of the NPs with N2 plasma-treated NPs acquiring the lowest bandgap. Lastly, the articleexamined the actual decomposition of RO-122 dye in wastewater by an Ar plasma treatment alone orcombined with the plasma-treated TCZ-GO NPs via spectrophotometric analyses, electrical conductivity,pH and total organic carbon (TOC) removal measurements. Moreover, the reactive species produced duringthe combined plasma/photocatalysis induced degradation were detected in situ by optical emissionspectroscopy. Results revealed that the processes carried out by combining N2 plasma-treated TCZ-GONPs and Ar plasma exhibited the highest degradation efficiency (85 %) due to the generation of moreOH and H2O2. Overall, it can be concluded that plasma-aided treatment processes used synergisticallyas indirect surface functionalization of TCZ-GO NPs and direct plasma treatment of wastewater are extremelyefficient in the degradation of toxic compounds and can be extrapolated to various environmentalapplications.
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Phytochemical and Antimicrobial Study of an Antidiabetic Plant: Scoparia dulcis L.
L. Pari,M. Latha,K.M. Ramkumar,P.N. Damodaran,V. Rajeshkannan,T. Suresh 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.3
The antimicrobial and antifungal effects of different concentrations of chloroform/methanol fractions of Sco-paria dulciswere investigated. The isolated fractions were tested against different bacteria like Salmonella typhii, Staphylo-coccus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Proteus vulgarisand fungal strains such asAlternaria macrospora, Candida albicans, Aspergillus niger, and Fusarium oxysporum. The isolated fractions exhibited sig-nificant antimicrobial and antifungal activity against all the tested organisms compared with respective reference drugs. Theisolated fractions of S. dulcisshowed properties like antimicrobial and antifungal activities that will enable researchers in turnto look for application-oriented principles.
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