Investigation of Raman and photoluminescence studies of reduced graphene oxide sheets

Krishnamoorthy, Karthikeyan,Veerapandian, Murugan,Mohan, Rajneesh,Kim, Sang-Jae Springer-Verlag 2012 Applied physics. A, Materials science & processing Vol.106 No.3

Titanium carbide sheet based high performance wire type solid state supercapacitors

Krishnamoorthy, Karthikeyan,Pazhamalai, Parthiban,Sahoo, Surjit,Kim, Sang-Jae Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.12

<P>Two dimensional sheets based on transition metal carbides have attracted much attention in electrochemical energy storage sectors. In this work, we demonstrated the fabrication and performance of titanium carbide based wire type supercapacitors (WSCs) towards next generation energy storage devices. The layered titanium carbide sheets were prepared<I>via</I>selective extraction of Al from the precursor Ti2AlC using hydrofluoric acid and are extensively characterized using X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform-infrared spectroscopy, and laser Raman spectral analyses, respectively. The X-ray photoelectron spectroscopy studies confirmed the presence of oxygen and fluorinated functional groups attached on the surface of titanium carbide. The electrochemical studies of the fabricated titanium carbide WSC devices showed ideal capacitive properties with a specific length capacitance of 3.09 mF cm<SUP>−1</SUP>(gravimetric capacitance of about 4.64 F g<SUP>−1</SUP>), and specific energy density of about 210 nW h cm<SUP>−1</SUP>(in length) or 315 mW h kg<SUP>−1</SUP>(in gravimetric) with excellent cycling stability. Further, a detailed examination of the capacitive and charge-transfer behavior of titanium carbide WSCs has been investigated<I>via</I>electrochemical impedance analysis using Nyquist and Bode plots. Additionally, we have also demonstrated the practical application of the titanium carbide WSCs, highlighting the path for their huge potential in energy storage and management sectors.</P>

Antibacterial Efficiency of Graphene Nanosheets against Pathogenic Bacteria via Lipid Peroxidation

Krishnamoorthy, Karthikeyan,Veerapandian, Murugan,Zhang, Ling-He,Yun, Kyusik,Kim, Sang Jae American Chemical Society 2012 The Journal of Physical Chemistry Part C Vol.116 No.32

<P>Graphene nanosheets are highly recognized for their utility toward the development of biomedical device applications. The present study investigated the antibacterial efficiency of graphene nanosheets against four types of pathogenic bacteria. Graphene nanosheets are synthesized by a hydrothermal approach (under alkaline conditions using hydrazine hydrate). UV–vis and X-ray diffraction show a maximum absorbance at 267 nm and appearance of new broad diffraction peak at 26°, which ensures the reduction of graphene oxide into graphene nanosheets. Stretching and bending vibrations of C–C bonds, chemical states, disorder, and defects associated with the graphene nanosheets are evaluated in comparison with graphene oxide. The minimum inhibitory concentration (MIC) of graphene nanosheets against pathogenic bacteria was evaluated by a microdilution method. MICs such as 1 μg/mL (against <I>Escherichia coli</I> and <I>Salmonella typhimurium</I>), 8 μg/mL (against <I>Enterococcus faecalis</I>), and 4 μg/mL (against <I>Bacillus subtilis</I>) suggest that graphene nanosheets have predominant antibacterial activity compared to the standard antibiotic, kanamycin. Measurement of free radical modulation activity of graphene nanosheets suggested the involvement of reactive oxygen species in antibacterial properties.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-32/jp3047054/production/images/medium/jp-2012-047054_0008.gif'></P>

Probing possible egress channels for multiple ligands in human CYP3A4: A molecular modeling study

Krishnamoorthy, Navaneethakrishnan,Gajendrarao, Poornima,Thangapandian, Sundarapandian,Lee, Yuno,Lee, Keun Woo Springer-Verlag 2010 Journal of molecular modeling Vol.16 No.4

Changes of arbuscular mycorrhizal traits and community structure with respect to soil salinity in a coastal reclamation land

Krishnamoorthy, R.,Kim, K.,Kim, C.,Sa, T. Elsevier Science B.V., Amsterdam. 2014 Soil biology & biochemistry Vol.72 No.-

A comprehensive knowledge on the relationship between soil salinity and arbuscular mycorrhizal fungi (AMF) is vital for a deeper understanding of ecosystem functioning under salt stress conditions. The objective of this study was to determine the effects of soil salinity on AMF root colonization, spore count, glomalin related soil protein (GRSP) and community structure in Saemangeum reclaimed land, South Korea. Soil samples were collected and grouped into five distinct salt classes based on the electrical conductivity of soil saturation extracts (ECse). Mycorrhizal root colonization, spore count and GASP were measured under different salinity levels. AMF community structure was studied through three complementary methods; spore morphology, terminal restriction fragment length polymorphism (T-RFLP) and denaturing gradient gel electrophoresis (DGGE). Results revealed that root colonization (P < 0.01), spore count (P < 0.01) and GRSP (P < 0.01) were affected negatively by soil salinity. Spore morphology and T-RFLP data showed predominance of AMF genus Glomus in Saemangeum reclaimed land. T-RFLP and DGGE analysis revealed significant changes in diversity indices between non (ECse < 2 dS/m) and extremely (ECse > 16 dS/m) saline soil and confirmed dominance of Glomus caledonium only in soils with ECse < 8 dS/m. However, ribotypes of Glomus mosseae and Glomus proliferum were ubiquitous in all salt classes. Combining spore morphology, T-RFLP and DGGE analysis, we could show a pronounced effect in AMF community across salt classes. The result of this study improve our understanding on AMF activity and dominant species present in different salt classes and will substantially expand our knowledge on AMF diversity in reclaimed lands. (C) 2014 Elsevier Ltd. All rights reserved.

Ruthenium sulfide nanoparticles as a new pseudocapacitive material for supercapacitor

Krishnamoorthy, Karthikeyan,Pazhamalai, Parthiban,Kim, Sang Jae Pergamon Press 2017 Electrochimica Acta Vol. No.

<P><B>Abstract</B></P> <P>Transition metal chalcogenides received much attention as high performance electrode materials for energy storage devices during this decade. In this article, we demonstrated the sonochemical preparation of cubic RuS<SUB>2</SUB> nanoparticles with average size in the range of 20nm and investigated their supercapacitive properties in detail using cyclic voltammetry, charge-discharge analysis and electrochemical impedance spectroscopy, respectively. The RuS<SUB>2</SUB> electrode delivered a specific capacitance of 85Fg<SUP>−1</SUP> at a constant discharge current density of 0.5mAcm<SUP>−1</SUP> using a three electrode configuration. The RuS<SUB>2</SUB> symmetric supercapacitor device delivered a specific capacitance of 17Fg<SUP>−1</SUP> and excellent cyclic stability of about 96.15% capacitance retention over 5000 cycles. The electrochemical impedance spectroscopy (Nyquist and Bode) analysis together with the frequency dependent capacitance (real and imaginary) studies confirmed the ideal capacitive nature of the RuS<SUB>2</SUB> supercapacitor. The experimental findings ensure the potential application of RuS<SUB>2</SUB> nanoparticles as a novel electrode material for electrochemical energy storage devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> RuS<SUB>2</SUB> nanoparticles were prepared via sonochemical approach. </LI> <LI> RuS<SUB>2</SUB> based symmetric supercapacitor (SC) device was fabricated. </LI> <LI> Symmetric RuS<SUB>2</SUB> SC device delivered a specific capacitance of 17Fg<SUP>−1</SUP>. </LI> <LI> The RuS<SUB>2</SUB> SC device possesses capacitance retention of about 96.15% over 5000 cycles. </LI> </UL> </P>

A highly efficient 2D siloxene coated Ni foam catalyst for methane dry reforming and an effective approach to recycle the spent catalyst for energy storage applications

Krishnamoorthy, Karthikeyan,M. S. P., Sudhakaran,Pazhamalai, Parthiban,Mariappan, Vimal Kumar,Mok, Young Sun,Kim, Sang-Jae The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.32

<P>The dry reforming of methane (DRM) using CO2 for the production of syngas (H2 and CO) has received increasing attention for reducing global CO2 emissions. The main drawback of DRM reactions is the limited reusability of the spent catalyst due to carbon deposition on its surface. Thus, designing an appropriate catalytic system is adequate to achieve increased syngas production with low carbon deposition, and developing smart strategies to reuse the carbon deposited spent catalyst is highly desirable. In this work, two dimensional siloxene sheet (silicon analog of graphene oxide) coated nickel foam is examined as a novel catalyst for the DRM reaction. The siloxene/Ni foam catalyst demonstrated superior catalytic performance in terms of conversion efficiencies (for CH4 and CO2) and syngas production (H2 and CO) with a high H2/CO ratio of 1.5. Further, the carbon deposited siloxene/Ni spent catalyst recovered after the DRM reaction was effectively re-utilized as electrodes for a symmetric supercapacitor (SSC) using an organic electrolyte. The fabricated SSC (using the spent catalyst as electrodes) delivered a high device capacitance (24.65 F g<SUP>−1</SUP>), high energy density (30.81 Wh kg<SUP>−1</SUP>), and high-power density (15 625 W kg<SUP>−1</SUP>) with a long cycle life. Considering that the estimated carbon cost for developing a supercapacitor electrode is about $15 per kilogram, our strategy to effectively reutilize the recovered carbon deposited spent catalyst for energy storage applications might be a promising and economical approach for utilization of the spent catalyst.</P>

CRYOPRESERVATION OF SPERM AND ITS QUALITY ASSESSMENT IN COBIA, Rachycentron canadum

Krishnamoorthy Dhanasekar,Natesan Munuswamy 한국수산과학회 양식분과 2015 한국수산과학회 양식분과 학술대회 Vol.2015 No.5

k-OUT-OF-n-SYSTEM WITH REPAIR : T-POLICY

Krishnamoorthy, A.,Rekha, A. 한국전산응용수학회 2001 The Korean journal of computational & applied math Vol.8 No.1

We consider a k-out-of-n system with repair under T-policy. Life time of each component is exponentially distributed with parameter $\lambda$. Server is called to the system after the elapse of T time units since his departure after completion of repair of all failed units in the previous cycle or until accumulation of n-k failed units, whichever occurs first. Service time is assumed to be exponential with rate ${\mu}$. T is also exponentially distributed with parameter ${\alpha}$. System state probabilities in finite time and long run are derived for (i) cold (ii) warm (iii) hot systems. Several characteristics of these systems are obtained. A control problem is also investigated and numerical illustrations are provided. It is proved that the expected profit to the system is concave in ${\alpha}$ and hence global maximum exists.

Mechanistic investigation on the toxicity of MgO nanoparticles toward cancer cells

Krishnamoorthy, Karthikeyan,Moon, Jeong Yong,Hyun, Ho Bong,Cho, Somi Kim,Kim, Sang-Jae The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.47

<P>Magnesium oxide nanoparticles (MgO NPs) are increasingly recognized for their applications in cancer therapy such as nano-cryosurgery and hyperthermia. The present study investigated the cytotoxic effects of magnesium oxide nanoparticles (MgO NPs) against normal lung fibroblast cells and different types of cancerous cells. MgO NPs exhibited a preferential ability to kill cancerous cells such as HeLa, AGS and SNU-16 cells. A detailed study has been undertaken to investigate the mechanism of cell death occurring in cancer cells (AGS cells) by the analysis of morphological changes, western blot analysis and flow cytometry measurements. Western blot analysis measurements suggested the role of apoptosis in cell death due to MgO exposure. MgO NPs enhanced ultrasound-induced lipid peroxidation in the liposomal membrane. Flow cytometry measurements using H<SUB>2</SUB>DCFDA showed that the toxicity of MgO NPs is attributed to the generation of reactive oxygen species, which further results in the induction of apoptosis in cancer cells. Our experimental results suggested the potential utility of MgO NPs in the treatment of cancer.</P> <P>Graphic Abstract</P><P>MgO nanoparticles exhibit an ability to kill cancer cells by inducing apoptosis through reactive oxygen species. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm35087d'> </P>