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( Manikantan Kota ),박호석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
We report synthesis of nitrogen doped three dimensional graphene (N-RGO) architectures. The detailed doping configurations analysed by XPS indicate the nitrogen content of around 6.2 at.%. The reduced graphene oxide has specific surface area of 190 ㎡ g<sup>-1</sup> and specific capacitance up to 217 F g<sup>-1</sup> at a scan rate of 5 mV s<sup>-1</sup>.The low charge transfer resistance confirmed by electrochemical impedance spectroscopy is associated with good rate capability. The N-RGO sample exhibits an excellent cyclic stability with no decay in capacitance even after 5000 cycles at scan rate of 100 mV s<sup>-1</sup>. A further study for high energy density supercapacitor (SC) is conducted by introducing micro porosity and 1-ethylimidazolium tetrafluoroborate (EMIMBF<sub>4</sub>) ionic liquid (IL) electrolyte in to the system, which is to be discussed.
Nitrogen-incorporated Mesoporous Restacking-inhibited Reduced Graphene Oxides for Supercapacitors
( Manikantan Kota ),박호석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Graphene, active electrode material owing to large surface area, and high electronic conductivity in supercapacitor (SCs) application. However, the current bottleneck is the fabrication of restacking-inhibited graphene. Herein, we demonstrate the synthesis of restacking-inhibited nitrogen doped graphene for SCs application. The d-spacing increases up to 0.352 nm and the surface area is s 698 ㎡ g<sup>-1</sup> with mesoporosity, which indicating restacking inhibition by N incorporation decomposed by melamine-formaldehyde. The SC performances of the as-modified RGO-based cells in organic electrolyte show the sp. capacitance of 16.9 F g<sup>-1</sup>, the energy density of 14.1 kW kg<sup>-1</sup> and 85% of capacitance retention for 5000 cycles, which are higher than those of pristine RGO-based cells.
Kota, Manikantan,Jana, Milan,Park, Ho Seok Elsevier 2018 Journal of Power Sources Vol.399 No.-
<P><B>Abstract</B></P> <P>The synthesis of nitrogen- and sulfur-doped three-dimensional (3D) graphene architectures further treated by steam activation to increase surface area is reported in this study. Tetraethylammonium tetrafluoroborate (TEABF<SUB>4</SUB>) in propylene carbonate as an organic electrolyte is used to enlarge the voltage range of a supercapacitor (SC) for high energy density. The 3D nitrogen- and sulfur-doped, steam activated, reduced graphene oxides (N-SRGO and S-SRGO) contained 7.84% and 6.93% of N and S heteroatoms and feature 497 m<SUP>2</SUP> g<SUP>−1</SUP> and 525 m<SUP>2</SUP> g<SUP>−1</SUP> of surface area due to hieratical porosity of the substance. As shown in the galvanic charge/discharge curves, a range of 0–2.5 V in the 3D N-SRGO architectures showed the highest capacitance of 23.1 F g<SUP>−1</SUP>, delivering maximum energy and power densities of up to 20 W h kg<SUP>−1</SUP> and 6190 W kg<SUP>−1</SUP>. The rate capability and cycle stability over 5000 cycles were evaluated to be 63% and 68%, respectively, for N-SRGO. This study provides a systematic way to improve energy density of SCs by combining heteroatom-doped 3D graphene architecture with an organic TEABF<SUB>4</SUB>/PC electrolyte.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The 3D hieratically porous doped graphene architecture is constructed. </LI> <LI> Heteroatoms are uniformly distributed onto the 3D graphene surface. </LI> <LI> A full cell supercapacitor is fabricated using organic electrolytes. </LI> <LI> Energy density of cell is enhanced improving specific capacitance and potential window. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kota, Manikantan,Park, Ho Seok Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.3
<P><B>Abstract</B></P> <P>Graphene is considered a promising active electrode material due to a large surface area, high electronic conductivity, and chemical and mechanical stabilities for supercapacitor (SC) applications. However, the current bottleneck is the fabrication of restacking-inhibited graphene on an electrode level which otherwise loses the capability to achieve the aforementioned properties. Herein, we demonstrate the synthesis of restacking-inhibited nitrogen (N)-incorporated mesoporous graphene for high energy SCs. The melamine-formaldehyde acts as a restacking inhibitor by forming a bonding with reduced graphene oxide (RGO) through a condensation reaction and as an N precursor to be decomposed to create open pores and N sources upon heat treatment. The d-spacing increases up to 0.352nm and the surface area is as high as 698m<SUP>2</SUP> g<SUP>−1</SUP> with high mesoporosity, confirming restacking inhibition by N incorporation decomposed by melamine-formaldehyde. The restacking-inhibited RGO-based SC cells in organic electrolyte show the specific capacitance of 25.8Fg<SUP>−1</SUP>, the energy density of 21.8kWkg<SUP>−1</SUP> and 85% of capacitance retention for 5000 cycles, which are better than those of pristine RGO-based cells. These improved SC performances are attributed to the fast ion transport through a mesoporous channel in crumpled structure and the doping effect of N incorporation. This work provides a simple yet effective chemical approach to fabricate restacking-inhibited RGO electrodes for improved SC performances.</P>
Hierarchical Structured, Nitrogen-Incorporated Graphene Aerogel for High Performance Supercapacitor
Xu Yu,Manikantan Kota,박호석 한국고분자학회 2017 Macromolecular Research Vol.25 No.10
The nitrogen (N)-doped reduced graphene aerogel (NRGA) with high Ndoping level is successfully fabricated via chemical converted method and thermal activation. N-atoms can be incorporated at a high temperature of 900 oC and distort the lattice structure of RGA by the formation of different N-configuration bindings. NRGA exhibits a larger surface area than GA, and the surface morphology is roughened as characterized by microscopic analysis. As confirmed by X-ray photoelectron spectroscopy (XPS) result, the pyridinic- and/or pyrrolic-N bindings modified electronic structures to improve the electrochemical properties. The specific capacitance of NRGA is increased to 289 F g-1 at 10 mV s-1 with rate capability of 75% and cyclic stability of 86%. These excellent electrochemical performances of NRGA are due to the synergistic structure effect which provide a large accessible area and rapid ion transfer pathways, as well as N-containing groups acting as the electrochemical active sites positioned at the edge or on-plane of NRGA lattices.
($\in,\;{\in} V q$)-FUZZY SUBNEAR-RINGS AND ($\in,\;{\in} V q$)-FUZZY IDEALS OF NEAR-RINGS
NARAYANAN, AL.,MANIKANTAN, T. 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.18 No.1
In this paper, we introduce the notions of ($\in,\;{\in} V q$)-fuzzy subnear-ring, ($\in,\;{\in} V q$)-fuzzy ideal and ($\in,\;{\in}V q$)-fuzzy quasi-ideal of near-rings and find more generalized concepts than those introduced by others. The characterization of such ($\in,\;{\in}V q$)-fuzzy ideals are also obtained.
INTERVAL-VALUED FUZZY IDEALS GENERATED BY AN INTERVAL-VALUED FUZZY SUBSET IN SEMIGROUPS
NARAYANAN, AL.,MANIKANTAN, T. 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.20 No.1
In this paper, we introduce the concept of an interval-valued fuzzy left (right, two-sided, interior, bi-) ideal generated by an interval-valued fuzzy subset in semigroups. Some characterizations of such generated interval-valued fuzzy ideals are also discussed.
The development of practice model for uterus auto-transplantation using domestic pigs
( Jae Young Pae ),( Arvind Manikantan Padma ),( Mats Hellstrom ),( Mihai Oltean ),( Mats Brannstrom ),( Min Jong Song ) 대한산부인과학회 2020 대한산부인과학회 학술대회 Vol.106 No.-
Objective: The present study aims to develop a practice model for uterus auto-transplantation using domestic pigs. Methods: Ten domestic pigs were used to develop a practice model. First 3 pigs are used for anatomical investigation to choose proper vessels used for anastomoses. Seven pigs were used to perform the uterus auto-transplantation. Under general anesthesia, the bicornuate uterus was carefully dissected and harvested with its bilateral feeding arteries and draining veins. The feeding arteries were bilateral umbilical arteries and the draining veins were bilateral ovarian arteries. After harvesting the uterus, bilateral arteries were cannulated immediately and the uterus was flushed with cold (+4 C) Custodiol (HTK) solution supplemented with xylocaine (0.4 mg/ml). The uterus was stored at +4 cooling chamber during during flushing. Flushed uterus was placed in its original position and the bilateral umbilical arteries and bilateral ovarian veins were anastomosed end to side to bilateral external iliac arteries and veins respectively. Indocyanine green (ICG) angiography was performed to monitor of reperfusion for 1hour. Results: Mean total operation time was 298 minutes and mean duration of donor surgery was 119 minutes. The mean cold ischemic time was 56 minutes and the mean warm ischemic time was 123 minutes. Estimated mean blood loss was 200 mL. All seven auto-transplanted pigs were considered well isolated and flushed. They also showed satisfactory reperfusion judged by change in gross appearance and ICG angiography. Conclusion: This study showed that a practice model for uterus auto-transplantation using domestic pigs is feasible and demonstrated that a satisfactory reperfusion could be achieved.