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      • KCI등재

        Clerodendrum chinense-mediated biofabrication of silver nanoparticles: Mosquitocidal potential and acute toxicity against non-target aquatic organisms

        Marimuthu Govindarajan,Mohan Rajeswary,S.L. Hoti,Kadarkarai MURUGAN,Kalimuthu Kovendan,Subramanian Arivoli,Giovanni Benelli 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.1

        Mosquito-borne diseases represent a deadly threat for millions of people worldwide. However, the use of synthetic insecticides to control Culicidae may lead to high operational costs and adverse non-target effects. Plantborne compounds have been proposed for rapid extracellular synthesis ofmosquitocidal nanoparticles. Their impact against biological control agents of mosquito larval populations has been poorly studied. In this study, we synthesized silver nanoparticles (Ag NPs) using the Clerodendrumchinense leaf extract as reducing and stabilizing agent. The biosynthesis of AgNP was confirmed analyzing the excitation of surface Plasmon resonance using ultraviolet–visible (UV–vis) spectrophotometry. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the clustered and irregular shapes of Ag NP. The presence of silver was determined by energy dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) spectroscopy analysis investigated the identity of secondary metabolites,which may act as Ag NP capping agents. The acute toxicity of C. chinense leaf extract and biosynthesized Ag NP was evaluated against larvae of Anopheles subpictus, Aedes albopictus and Culex tritaeniorhynchus. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against A. subpictus, A. albopictus, and C. tritaeniorhynchus with LC50 values of 10.23, 11.10 and 12.38 μg/mL, respectively. Biosynthesized Ag NPswere found safer to non-target organisms Diplonychus indicus, Anisops bouvieri and Gambusia affinis, with respective LC50 values ranging from647.05 to 6877.28 μg/ml. Overall, our results highlight that C. chinense-fabricated Ag NP are a promising and eco-friendly tool against larval populations ofmosquito vectors of medical and veterinary importance, with negligible toxicity against non-target aquatic organisms. © 2015 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection

      • SCIESCOPUSKCI등재

        Enhanced OLSR for Defense against DOS Attack in Ad Hoc Networks

        Marimuthu, Mohanapriya,Krishnamurthi, Ilango The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.1

        Mobile ad hoc networks (MANET) refers to a network designed for special applications for which it is difficult to use a backbone network. In MANETs, applications are mostly involved with sensitive and secret information. Since MANET assumes a trusted environment for routing, security is a major issue. In this paper we analyze the vulnerabilities of a pro-active routing protocol called optimized link state routing (OLSR) against a specific type of denial-of-service (DOS) attack called node isolation attack. Analyzing the attack, we propose a mechanism called enhanced OLSR (EOLSR) protocol which is a trust based technique to secure the OLSR nodes against the attack. Our technique is capable of finding whether a node is advertising correct topology information or not by verifying its Hello packets, thus detecting node isolation attacks. The experiment results show that our protocol is able to achieve routing security with 45% increase in packet delivery ratio and 44% reduction in packet loss rate when compared to standard OLSR under node isolation attack. Our technique is light weight because it doesn't involve high computational complexity for securing the network.

      • Real-time electrical measurement of L929 cellular spontaneous and synchronous oscillation

        Marimuthu, Mohana,Park, Cheolsoo,Kim, Sanghyo,Choi, Cheol Soo Dove Medical Press 2012 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.7 No.-

        <P>Nonexcitable cell types, fibroblasts of heart muscle or astrocytes, are well known for their spontaneous Ca<SUP>2+</SUP> oscillations. On the other hand, murine fibroblast (L929) cells are known to be deficient in cell–cell adhesive proteins and therefore lack gap junctions for cellular communication. However, these cells exhibit a unique property of collectively synchronized and spontaneous oscillation, as revealed by real-time monitoring of cells cultured on a 250-μm diameter microelectrode for more than 3 days using an electrical cell-substrate impedance-sensing system (ECIS). Live-cell imaging is a widely used technique for oscillation detection, but it has limitations relating to cellular physiological environment maintenance for microscopic analysis and for prolonged periods of study. The present research emphasizes an electrical-sensing technique (ECIS) capable of overcoming the most important issues inherent in live-cell imaging systems for the detection of L929 cellular spontaneous and synchronized oscillation in real-time for longer periods. Possible mechanisms involved in L929 oscillation were elucidated to be periodic extension/contraction of lamellipodia continued as blebbing, which is produced by signals from the actomyosin complex initiated by connexin hemichannel opening and adenosine triphosphate (ATP) release. By applying the connexin hemichannel inhibitor, flufenamic acid, the hindrance of ATP release and calcium transients were analyzed to elucidate this hypothesis.</P>

      • KCI등재

        Bi-Directional and Uni-Directional Bending Fatigue Performance of Unreinforced and Carbon Fiber Reinforced Polyamide 66 Spur Gears

        Marimuthu Kodeeswaran,Arnika Verma,Rajamanickam Suresh,Selvaraj Senthilvelan 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.8

        Gears are generally subjected to uni-directional cyclic loads, however, in applications like actuators of satellite launchers, gears experience bi-directional cyclic loads due to its rotation in both clockwise and counter clockwise directions. In the present study, bidirectional and uni-directional bending fatigue performance of injection molded unreinforced and carbon fiber reinforced polyamide 66 gears were evaluated using a test rig developed in-house. During testing, torque applied and the angular displacement of the gears were continuously recorded. The net surface temperature measured by an infrared camera was higher for the gears subjected to bidirectional loading as compared to uni-directional loading. Reinforced gears exhibited about 84% lower temperature than that of unreinforced gears, due to lesser material hysteresis and better thermal conductivity. Fatigue failure of unreinforced gears exhibited almost straight root cracks and confirmed ductile failure. Fatigue failure of reinforced gears exhibited tortuous crack path due to the existence of reinforced fibers. For both the type of loads, carbon fiber reinforced gears exhibited superior bending performance than unreinforced gears (2-51 times) due to its improved mechanical and thermal properties. Significant fatigue life reduction (83-99%) of the tested gears, were observed when subjected to bi-directional loading when compared to that of uni-directional loading.

      • KCI등재

        One-pot fabrication of silver nanocrystals using Ormocarpum cochinchinense: Biophysical characterization of a potent mosquitocidal and toxicity on non-target mosquito predators

        Marimuthu Govindarajan,Giovanni Benelli 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.2

        Mosquito vectors (Diptera: Culicidae) are vectors of pathogens and parasites of public health importance, including malaria, dengue, chikungunya, Japanese encephalitis, lymphatic filariasis and Zika virus. Novel eco-friendly control tools against Culicidae are a priority. In this research, silver nanoparticles (Ag NPs) were rapidly synthesized using the aqueous leaf extract of Ormocarpum cochinchinense as a cheap, non-toxic material. The bioreduced Ag NPs were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction analysis (XRD). The acute toxicity of O. cochinchinense leaf extract and synthesized Ag NP was evaluated against larvae of the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti and the filariasis vector Culex quinquefasciatus. Compared to the leaf aqueous extract, synthesized Ag NPs showed high toxicity against A. stephensi, A. aegypti and C. quinquefasciatus, with LC50 values of 10.43, 11.26 and 12.35 μg/mL, respectively. Synthesized Ag NPs were found safer to non-target mosquito predators Diplonychus indicus and Gambusia affinis, with LC50 values ranging from 522.13 to 637.70 μg/mL. Overall, this study firstly shed light to O. cochinchinense's potential as a bioresource for rapid, cheap and effective nanosynthesis of mosquitocides.

      • Amphiphilic triblock copolymer and a microfluidic device for porous microfiber fabrication

        Marimuthu, Mohana,Kim, Sanghyo,An, Jeongho Royal Society of Chemistry 2010 SOFT MATTER Vol.6 No.10

        <P>This paper shows successful fabrication of different diameter porous microfibers using a novel, simple and cost effective polydimethylsiloxane (PDMS)-based microfluidic device in which an amphiphilic ABA triblock copolymer, poly(<I>p</I>-dioxanone-<I>co</I>-caprolactone)-<I>block</I>-poly(ethylene oxide)-<I>block</I>-poly(<I>p</I>-dioxanone-<I>co</I>-caprolactone) (PPDO-<I>co</I>-PCL-<I>b</I>-PEG-<I>b</I>- PPDO-<I>co</I>-PCL) in dichloromethane (CH<SUB>2</SUB>Cl<SUB>2</SUB>), and de-ionized water (DI H<SUB>2</SUB>O) were taken in two inlets to extrude porous fibers through the outlet utilizing a dual mechanism of immersion precipitation and solvent evaporation. The flow rates of the two inlet solutions (core and sheath) were controlled such that 5–50 μl min<SUP>−1</SUP> and 100 ml h<SUP>−1</SUP> were used, respectively, to produce 2–200 μm diameter porous microfibers. Controlled fibronectin (an adhesive protein) release from the scaffold was observed until 8 weeks in an <I>in vitro</I> protein release study, which could be due to the slower scaffold PCL block degradation rate until 8 weeks of the <I>in vitro</I> degradation analysis. Cytocompatibility of our porous scaffold was demonstrated for its applicability as a cell culture scaffold or implant material by means of analysis of surface hydrophilicity (water and cell suspension contact angles) and mitochondrial activity (WST-1 proliferation test) using L929 mouse fibroblasts cell line. In summary, the experimental results suggest that combined use of the microfluidic device and amphiphilic triblock copolymer produces varied diameter porous fiber scaffolds which can be potentially used as a controlled protein/drug release carrier for tissue regeneration and/or drug delivery applications.</P> <P>Graphic Abstract</P><P>Porous microfibers with different diameters were successfully fabricated using a novel, simple and cost effective polydimethylsiloxane (PDMS)-based microfluidic device in which an amphiphilic ABA triblock copolymer was used. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b924704a'> </P>

      • Spherical indentation for brittle fracture toughness evaluation by considering kinked-cone-crack

        Marimuthu, Karuppasamy Pandian,Rickhey, Felix,Lee, Jin Haeng,Lee, Hyungyil Elsevier 2017 Journal of the European Ceramic Society Vol.37 No.1

        <P><B>Abstract</B></P> <P>This work aims at evaluating the fracture toughness of brittle materials by spherical indentation. The cone-cracking is simulated by the extended finite element method (XFEM) in Abaqus. The formation of a kinked-cone-crack is observed when the indenter comes into (second) contact with the surface part outside the ring-crack. The effects of friction, Poisson’s ratio and cone-crack kinking on the Roesler’s constant <I>κ<SUB>c</SUB> </I> are analyzed. Based on numerical results, the Roesler’s method for evaluating the fracture toughness is enhanced by considering kinked-cone-crack. By performing systematic XFE analyses, a database for enhanced Roesler’s constant <I>κ<SUB>c</SUB> </I> | <SUB>kink</SUB> is provided for the fracture toughness evaluation of brittle materials. Finally, the proposed method is verified by conducting spherical indentation tests on soda-lime glass specimens.</P>

      • SCOPUSKCI등재

        Gum-Resinosis in Mangifera indica

        Marimuthu, Jayabalan,Rajarathinam, Kaniayappanadar,Jayakumar, Muthukrishnan,Kil, Bong-Seop,Kulandaivelu, Govindasamy The Ecological Society of Korea 2001 Journal of Ecology and Environment Vol.24 No.2

        Gums, resins and gum-resins represent a variety of plant exudates that are highly prized and are extensively used in various industries. The usage of water soluble gums is growing at faster rate as they are excellent suspending agents, dispersants stabilizing agents, emulsifiers and gel forming agents. The gums are made up of carbohydrate polymers, composed of sugar units glycosidically condensed to form large molecules. Resins are non-volatile products, and oxidative products of terpenes or fatty acids, and are of greater commercial importance. They are soluble in water and contrasted with gums, soluble in organic solvents only.

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