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Search Results: 1 - 10 of 130382 matches for " Eppakayala V "
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Green synthesis of graphene and its cytotoxic effects in human breast cancer cells
Gurunathan S, Han JW, Eppakayala V, Kim JH
International Journal of Nanomedicine , 2013, DOI: http://dx.doi.org/10.2147/IJN.S42047
Abstract: een synthesis of graphene and its cytotoxic effects in human breast cancer cells Original Research (564) Total Article Views Authors: Gurunathan S, Han JW, Eppakayala V, Kim JH Published Date March 2013 Volume 2013:8 Pages 1015 - 1027 DOI: http://dx.doi.org/10.2147/IJN.S42047 Received: 24 December 2012 Accepted: 27 January 2013 Published: 11 March 2013 Sangiliyandi Gurunathan, Jae Woong Han, Vasuki Eppakayala, Jin-Hoi Kim Department of Animal Biotechnology, Konkuk University, Seoul, South Korea Background: This paper describes an environmentally friendly (“green”) approach for the synthesis of soluble graphene using Bacillus marisflavi biomass as a reducing and stabilizing agent under mild conditions in aqueous solution. In addition, the study reported here investigated the cytotoxicity effects of graphene oxide (GO) and bacterially reduced graphene oxide (B-rGO) on the inhibition of cell viability, reactive oxygen species (ROS) generation, and membrane integrity in human breast cancer cells. Methods: The reduction of GO was characterized by ultraviolet–visible spectroscopy. Size distribution was analyzed by dynamic light scattering. Further, X-ray diffraction and high-resolution scanning electron microscopy were used to investigate the crystallinity of graphene and the morphologies of prepared graphene, respectively. The formation of defects further supports the bio-functionalization of graphene, as indicated in the Raman spectrum of B-rGO. Surface morphology and the thickness of the GO and B-rGO were analyzed using atomic force microscopy, while the biocompatibility of GO and B-rGO were investigated using WST-8 assays on MCF-7 cells. Finally, cellular toxicity was evaluated by ROS generation and membrane integrity assays. Results: In this study, we demonstrated an environmentally friendly, cost-effective, and simple method for the preparation of water-soluble graphene using bacterial biomass. This reduction method avoids the use of toxic reagents such as hydrazine and hydrazine hydrate. The synthesized soluble graphene was confirmed using various analytical techniques. Our results suggest that both GO and B-rGO exhibit toxicity to MCF-7 cells in a dose-dependent manner, with a dose > 60 μg/mL exhibiting obvious cytotoxicity effects, such as decreasing cell viability, increasing ROS generation, and releasing of lactate dehydrogenase. Conclusion: We developed a green and a simple approach to produce graphene using bacterial biomass as a reducing and stabilizing agent. The proposed approach confers B-rGO with great potential for various biological and biomedical applications.
Oxidative stress-mediated antibacterial activity of graphene oxide and reduced graphene oxide in Pseudomonas aeruginosa
Gurunathan S, Han JW, Dayem AA, Eppakayala V, Kim JH
International Journal of Nanomedicine , 2012, DOI: http://dx.doi.org/10.2147/IJN.S37397
Abstract: ative stress-mediated antibacterial activity of graphene oxide and reduced graphene oxide in Pseudomonas aeruginosa Original Research (1723) Total Article Views Authors: Gurunathan S, Han JW, Dayem AA, Eppakayala V, Kim JH Published Date November 2012 Volume 2012:7 Pages 5901 - 5914 DOI: http://dx.doi.org/10.2147/IJN.S37397 Received: 27 August 2012 Accepted: 08 October 2012 Published: 30 November 2012 Sangiliyandi Gurunathan, Jae Woong Han, Ahmed Abdal Dayem, Vasuki Eppakayala, Jin-Hoi Kim Department of Animal Biotechnology, Konkuk University, Seoul, South Korea Background: Graphene holds great promise for potential use in next-generation electronic and photonic devices due to its unique high carrier mobility, good optical transparency, large surface area, and biocompatibility. The aim of this study was to investigate the antibacterial effects of graphene oxide (GO) and reduced graphene oxide (rGO) in Pseudomonas aeruginosa. In this work, we used a novel reducing agent, betamercaptoethanol (BME), for synthesis of graphene to avoid the use of toxic materials. To uncover the impacts of GO and rGO on human health, the antibacterial activity of two types of graphene-based material toward a bacterial model P. aeruginosa was studied and compared. Methods: The synthesized GO and rGO was characterized by ultraviolet-visible absorption spectroscopy, particle-size analyzer, X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Further, to explain the antimicrobial activity of graphene oxide and reduced graphene oxide, we employed various assays, such as cell growth, cell viability, reactive oxygen species generation, and DNA fragmentation. Results: Ultraviolet-visible spectra of the samples confirmed the transition of GO into graphene. Dynamic light-scattering analyses showed the average size among the two types of graphene materials. X-ray diffraction data validated the structure of graphene sheets, and high-resolution scanning electron microscopy was employed to investigate the morphologies of prepared graphene. Raman spectroscopy data indicated the removal of oxygen-containing functional groups from the surface of GO and the formation of graphene. The exposure of cells to GO and rGO induced the production of superoxide radical anion and loss of cell viability. Results suggest that the antibacterial activities are contributed to by loss of cell viability, induced oxidative stress, and DNA fragmentation. Conclusion: The antibacterial activities of GO and rGO against P. aeruginosa were compared. The loss of P. aeruginosa viability increased in a dose- and time-dependent manner. Exposure to GO and rGO induced significant production of superoxide radical anion compared to control. GO and rGO showed dose-dependent antibacterial activity against P. aeruginosa cells through the generation of reactive oxygen species, leading to cell death, which was further confirmed through resulting nuclear fragmentation. The data presented here are novel in
Green synthesis of graphene and its cytotoxic effects in human breast cancer cells
Gurunathan S,Han JW,Eppakayala V,Kim JH
International Journal of Nanomedicine , 2013,
Abstract: Sangiliyandi Gurunathan, Jae Woong Han, Vasuki Eppakayala, Jin-Hoi Kim Department of Animal Biotechnology, Konkuk University, Seoul, South Korea Background: This paper describes an environmentally friendly (“green”) approach for the synthesis of soluble graphene using Bacillus marisflavi biomass as a reducing and stabilizing agent under mild conditions in aqueous solution. In addition, the study reported here investigated the cytotoxicity effects of graphene oxide (GO) and bacterially reduced graphene oxide (B-rGO) on the inhibition of cell viability, reactive oxygen species (ROS) generation, and membrane integrity in human breast cancer cells. Methods: The reduction of GO was characterized by ultraviolet–visible spectroscopy. Size distribution was analyzed by dynamic light scattering. Further, X-ray diffraction and high-resolution scanning electron microscopy were used to investigate the crystallinity of graphene and the morphologies of prepared graphene, respectively. The formation of defects further supports the bio-functionalization of graphene, as indicated in the Raman spectrum of B-rGO. Surface morphology and the thickness of the GO and B-rGO were analyzed using atomic force microscopy, while the biocompatibility of GO and B-rGO were investigated using WST-8 assays on MCF-7 cells. Finally, cellular toxicity was evaluated by ROS generation and membrane integrity assays. Results: In this study, we demonstrated an environmentally friendly, cost-effective, and simple method for the preparation of water-soluble graphene using bacterial biomass. This reduction method avoids the use of toxic reagents such as hydrazine and hydrazine hydrate. The synthesized soluble graphene was confirmed using various analytical techniques. Our results suggest that both GO and B-rGO exhibit toxicity to MCF-7 cells in a dose-dependent manner, with a dose > 60 μg/mL exhibiting obvious cytotoxicity effects, such as decreasing cell viability, increasing ROS generation, and releasing of lactate dehydrogenase. Conclusion: We developed a green and a simple approach to produce graphene using bacterial biomass as a reducing and stabilizing agent. The proposed approach confers B-rGO with great potential for various biological and biomedical applications. Keywords: Bacillus marisflavi, graphene oxide, reduced graphene oxide, ultraviolet–visible spectroscopy, Raman spectroscopy
Synthesis of SnO Nanopatricles—A Hydrothermal Approach  [PDF]
Eppakayala Janardhan, Mettu Maheshwar Reddy, Pendyala Venkat Reddy, Madireddy Jaipal Reddy
World Journal of Nano Science and Engineering (WJNSE) , 2018, DOI: 10.4236/wjnse.2018.82002
Abstract: SnO nanoparticles were prepared by addition of HCl to tin oxide solution. The synthesis process is simplified for SnO nuclei. We herein report a better-defined and simple procedure for synthesis of SnO particles in a simple hydrothermal process.
Nonsmooth Optimization Algorithms in Some Problems of Fracture Dynamics  [PDF]
V. V. Zozulya
Intelligent Information Management (IIM) , 2010, DOI: 10.4236/iim.2010.211073
Abstract: Mathematical statement of elastodynamic contact problem for cracked body with considering unilateral restrictions and friction of the crack faces is done in classical and weak forms. Different variational formulations of unilateral contact problems with friction based on boundary variational principle are considered. Nonsmooth optimization algorithms of Udzawa’s type for solution of unilateral contact problem with friction have been developed. Convergence of the proposed algorithms has been studied numerically.
Precessing Ball Solitons as Self-Organizing Systems during a Phase Transition in a Ferromagnet  [PDF]
V. V. Nietz
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410A3010
Abstract:

Precessing ball solitons (PBS) in a ferromagnet during the first order phase transition is induced by a magnetic field directed along the axis of anisotropy, while the action of the periodic field perpendicular to the main magnetic field has been analyzed. Under these conditions, the characteristics of arising equilibrium PBS are uniquely determined by the frequency of the periodic field, but the solitons with other frequencies are impossible. For such structure, the entropy increase connected with dissipation is compensated by the decrease of the entropy due to the external periodic field. It is shown that the equilibrium PBS are essentially the “self-organizing systems” that can arise spotaneously in a metastable state of ferromagnet.

Movement of Self-Organizing Solitons in Ferromagnet  [PDF]
V. V. Nietz
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.610155
Abstract: Precessing ball solitons (PBS) in a ferromagnet during the first order phase transition induced by a magnetic field directed along the axis of anisotropy, while the additional action of high-frequency field perpendicular to the main magnetic field, are analyzed. It is shown that the spatial motion of solitons, associated with thermal fluctuations in the crystal, does not destroy the equilibrium of self-organized PBS.
Lα Line of Dark Positronium as a Nongravitational Detection of DM  [PDF]
V. Burdyuzha, V. Charugin
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.613187
Abstract: An attempt to predict the new atomic dark matter lines is done on the example of a dark lepton atom-positronium. Its Layman-alpha line with the energy near 3 GeV may be observable if the appropriate conditions are realized. For this we have studied a γ-ray excess in the center of our galaxy. In principle, this excess may be produced by the Lα line of a dark positronium in the medium with Compton scattering. The possibility of observations of an annihilation line (E~300 TeV) of dark positronium is also predicted. Other proposals to observe the atomic dark matter are shortly described. Besides, Hα line (1.3μ) of usual positronum must be observable in the direction on the center of our galaxy.
Randomization of Energy and Momentum in Statistical Mechanics  [PDF]
V. V. Paranjape
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.615223
Abstract: Particle-particle collisions in materials give rise to a particle distribution in energy and momentum in such a way that a most probable distribution is realized. I will show that an evaporating liquid generates a molecular imbalance in the equilibrium energy distribution. The molecular collisions by their inherent nature are able to repair the imbalance and in so doing it is shown that the liquids cool down. Similarly an external electric field creates substantial imbalance in the momentum distribution for the electrons in ionic semiconductors. Electron-electron collisions are able to restore the imbalance and as a consequence, similar to the evaporating liquid, the electron gas loses thermal energy and cools down.
基于税收能力视角的中国税制改革 China s Tax Reform Based on the Perspective of Tax Capacity
v
- , 2015,
Abstract: 摘要 税收能力是研究税收制度的重要视角,科学判定税收能力是税制改革的基本前提。税收制度决定了既定条件下税收能力的高低,税收能力也影响和制约着税制改革的进程。我国近年来的经济社会发展改变了经济运行中各经济主体的税收能力及其格局。基于税收能力视角,现行税收制度在税制结构、税制体系、征管制度等方面还存在着与经济社会发展不相适应之处。为此,税制改革应基于对目前及未来税收能力的科学判断,明确税制结构优化的方向和路径,加快地方税体系建设,进一步完善税收征管制度。
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