인도 : 재외 인도인에 관한 모든 것

Monica Samal 포스코경영연구원 2007 CHINDIA Plus Vol.8 No.-

Synthesis, characterization and electrochemical properties of different morphological ZnO anchored on graphene oxide sheets

Zhong, Linlin,Samal, Monica,Yun, Kyusik Elsevier 2018 Materials chemistry and physics Vol.204 No.-

<P><B>Abstract</B></P> <P>In this study, we reported an optimized facile method to synthesize ZnO particles of three kinds of morphologies, flower-like, rod-like and sphere. Although ZnO grew along the a- and c-axes, however, the anisotropic crystal growth mechanism of ZnO particles was investigated by the ratio of precursor and temperature of the reaction. The characterizations of three ZnO particles were measured by Field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy and X-ray diffraction. In addition, ZnO with three shapes was fixed on gold-printed circuit board to detect their electrochemistry property in a 3% H<SUB>2</SUB>O<SUB>2</SUB>/phosphate buffer, while ZnO/GO (graphene oxide) composite was obtained by organic linking which showed the different electrochemical results compare to that of ZnO. electron-transfer distance and speed have been changed between the products and support due to the combination of ZnO and GO. The exploration of ZnO of different shape and ZnO/GO composites on their features and properties would provide significant evidence for their application as sensors in extensive fields.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three types of ZnO particles are synthesized successfully by facile method. </LI> <LI> The mechanism of ZnO growth in the aqueous solution is proposed. </LI> <LI> The ZnO particles were decorated on the surface of graphene oxide sheets. </LI> <LI> ZnO and ZnO/GO composites can be applied in analyzation of H<SUB>2</SUB>O<SUB>2</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic of electrochemical reaction on ZnO and ZnO/GO composites modified Au-PCB electrode, respectively. Insert image is rod-like ZnO particles and rod-like ZnO/GO composites.</P> <P>[DISPLAY OMISSION]</P>

인도 IT 산업, 문제점은 없나 ; 인도 IT 산업 왜 강한가 -인적자원 및 다국적기업과의 교류가 원동력-

박경서,모니카사말 ( Monica Samal ) 포스코경영연구원 2006 CHINDIA Plus Vol.4 No.-

A Ge inverse opal with porous walls as an anode for lithium ion batteries

Song, Taeseup,Jeon, Yeryung,Samal, Monica,Han, Hyungkyu,Park, Hyunjung,Ha, Jaehwan,Yi, Dong Kee,Choi, Jae-Man,Chang, Hyuk,Choi, Young-Min,Paik, Ungyu The Royal Society of Chemistry 2012 ENERGY AND ENVIRONMENTAL SCIENCE Vol.5 No.10

<P>Germanium holds great potential as an anode material for lithium ion batteries due to its large theoretical energy density and excellent intrinsic properties related to its kinetics associated with lithium and electrons. However, the problem related to the tremendous volume change of Ge during cycling is the dominant obstacle for its practical use. The previous research has focused on the improvement in mechanics associated with lithium without consideration of the kinetics. In this study, we demonstrate that the configuration engineering of the Ge electrode enables the improvement in kinetics as well as favorable mechanics. Two types of Ge inverse opal structures with porous walls and dense walls were prepared using a confined convective assembly method and by adjusting Ge deposition parameters in a chemical vapor deposition system. The Ge inverse opal electrode with porous walls shows much improved electrochemical performances, especially cycle performance and rate capability, than the electrode with dense walls. These improvements are attributed to a large free surface, which offers a facile strain relaxation pathway and a large lithium flux from the electrolyte to the active material.</P> <P>Graphic Abstract</P><P>A Ge inverse opal with porous walls shows excellent electrochemical performances due to a large free surface, which offers a facile strain relaxation pathway and a large lithium flux from the electrolyte to the active material. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2ee22358a'> </P>

Evaluation of physico-mechanical properties in NHDF and HeLa cell with treatment of graphene quantum dots using atomic force microscopy

Jeon, Seong-Beom,Yi, Se Won,Samal, Monica,Park, Keun-Hong,Yun, Kyusik Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.437 No.-

<P><B>Abstract</B></P> <P>We investigated the biocompatibility of GQDs in terms of the cellular response, an aspect often overlooked. Herein, we synthesized two types of GQDs – Glu-GQDs (GQDs which are derived from glucose) and Gr-GQDs (GQDs which are derived from graphite) – with different functional groups on their surfaces. Both types of GQDs shared similar morphological features (shape and size distribution); the size distribution varied between 1.5 nm to 9.5 nm in both cases. Spectral analysis confirmed the difference in their chemical composition. The presence of nitrogen and chlorine in the Glu-GQDs is the major distinction between the two types of GQDs. Fluorescence emission of the obtained GQDs was observed at 480 nm for the Glu-GQDs, and at 550 nm for the Gr-GQDs. The cytotoxicity in NHDF and HeLa cell line was evaluated by a CCK-8 assay, and it confirmed that the cell viability was above 80% despite the high concentration (1024 μg/mL) in both cases. Cellular response after GQDs treatment was different from the control, but it was not lethal in the cell viability aspect. Furthermore, the potential of the GQDs as bio-imaging agents was examined using a fluorescence microscope and a laser scanning confocal microscope. The Glu-GQDs dispersed throughout the cells in NHDF and HeLa cell line, while the Gr-GQDs dispersed in the cytoplasm of the NHDF cells, and were distributed throughout the cell in HeLa. This study demonstrates that GQDs have potential in biomedical applications, even though their functionalities may be different.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Investigation of biocompatibility of graphene quantum dots in terms of cellular response, an aspect often overlooked. </LI> <LI> Similar shape and size distribution, but different functional groups, fluorescence behavior. </LI> <LI> Assessment of cytotoxicity and evaluation of physico-mechanical changes of cells treated with graphene quantum dots. </LI> <LI> Envision a potential for bio-imaging agents. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Highly stable functionalized cuprous oxide nanoparticles for photocatalytic degradation of methylene blue

Kumar, Mohit,Das, Rupasree Ragini,Samal, Monica,Yun, Kyusik Elsevier 2018 Materials chemistry and physics Vol.218 No.-

<P><B>Abstract</B></P> <P>We report the synthesis and characterization of Cu<SUB>2</SUB>O nanoparticles (NPs) in the presence of the coordinating ligands like <SMALL>L</SMALL>-glutamic acid (Glu-Cu<SUB>2</SUB>O) and <SMALL>D</SMALL>-glucosamine (GlcN-Cu<SUB>2</SUB>O). Even if –NH<SUB>2</SUB> group is common to both the ligands, <SMALL>L</SMALL>-glutamic acid is a straight chain compound containing additional two –COOH groups, whereas, glucosamine is a cyclic compound with additional four –OH groups and an ether (-O-) linkage. Thus the coordinating ligands are different in the nature of the functional groups as well as their molecular skeletons leading to cubic morphology (∼350 nm of average edge length) for <SMALL>L</SMALL>-glutamic acid coordinated Cu<SUB>2</SUB>O and spherical morphology (∼250 nm of average diameter) for glucosamine one as observed by Field Effective Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) images. The observed band gap of Cu<SUB>2</SUB>O of 1.89 eV is decreased to 1.84 ev for both the ligated structures. Both the ligated cuprous oxide (Cu<SUB>2</SUB>O) nanoparticles (NPs) were used for the photocatalytic degradation of methylene Blue (MB). The spherical GlcN-Cu<SUB>2</SUB>O showed 98% degradation of MB in 105 min and after 3 cycles of operation, the photocatalytic activity was enough for the 93% degradation of the dye, whereas, the cubic Gu-Cu<SUB>2</SUB>O could degrade MB up to 97% in 135 min and after three cycles, only 86% of the dye was degraded. This indicates, the molecular skeleton and functional groups on the ligand control the shape and size of the Cu<SUB>2</SUB>O nanoparticles as well as the photocatalytic efficiency and stability. It is presumed, the cyclic glucosamine ligand can protect the Cu<SUB>2</SUB>O nanoparticles from erosion during the degradation process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Different structure of functionalized Cu<SUB>2</SUB>O was synthesized. </LI> <LI> NH<SUB>2</SUB> group is common to both the ligands. </LI> <LI> Photocatalytic dye degradation was done. </LI> <LI> Synthesized nanomaterials were highly stable up to third cycle. </LI> </UL> </P>

Synthesis, Characterization, and Antibacterial Properties of Silver Nanoparticles-Graphene and Graphene Oxide Composites

Huifang Liu,Linlin Zhong,윤규식,Monica Samal 한국생물공학회 2016 Biotechnology and Bioprocess Engineering Vol.21 No.1

In the field of nanotechnology, silver nanoparticles have been considered a promising antibacterial material for a century. The potential applications of graphene-based materials are increasingly recognized for their special physico-chemical and biological properties. In particular, graphene and graphene oxide as the foundation of nanocomposites have garnered much interest among researchers in many fields. In this review, we concentrate on different aspects of silver nanoparticle composites with graphene and graphene oxide, focusing on their synthesis methods, special characteristics, and antibacterial properties; we also briefly discuss limitations and future research.

Vertical Pillar-Superlattice Array and Graphene Hybrid Light Emitting Diodes

Lee, Jung Min,Choung, Jae Woong,Yi, Jaeseok,Lee, Dong Hyun,Samal, Monica,Yi, Dong Kee,Lee, Chul-Ho,Yi, Gyu-Chul,Paik, Ungyu,Rogers, John A.,Park, Won Il American Chemical Society 2010 NANO LETTERS Vol.10 No.8

<P>We report a type of device that combines vertical arrays of one-dimensional (1D) pillar-superlattice (PSL) structures with 2D graphene sheets to yield a class of light emitting diode (LED) with interesting mechanical, optical, and electrical characteristics. In this application, graphene sheets coated with very thin metal layers exhibit good mechanical and electrical properties and an ability to mount, in a freely suspended configuration, on the PSL arrays as a top window electrode. Optical characterization demonstrates that graphene exhibits excellent optical transparency even after deposition of the thin metal films. Thermal annealing of the graphene/metal (Gr/M) contact to the GaAs decreases the contact resistance, to provide enhanced carrier injection. The resulting PSL-Gr/M LEDs exhibit bright light emission over large areas. The result suggests the utility of graphene-based materials as electrodes in devices with unusual, nonplanar 3D architectures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2010/nalefd.2010.10.issue-8/nl100648y/production/images/medium/nl-2010-00648y_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl100648y'>ACS Electronic Supporting Info</A></P>