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고분자 전해질 연료전지용 Sulfonated Poly(ether sulfone)의 합성 및 특성 평가
김형준(Krishnan, N.N.),조은애(Kim, H.-J.),오인환(Prasanna, M.),홍성안(Cho, E.-A.),임태훈(Oh, I.-H.),Hong, S.-A.,Lim, T.-H. 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06
Sulfonated poly(ether sulfone) copolymers (PESs) were synthesized using hydroquinone 2-potassium sulfonate (HPS) with other monomers (bisphenol A and 4-fluorophenyl sulfone). PESs with different mole% of hydrophilic group were prepared by changing the mole ratio of HPS in the polymerization reaction. The chemical structure and the thermal stability of these polymers were characterized by using ¹H-NMR, FT-IR and TGA techniques. The PES 60 membrane, which has 60 mole% of HPS unit in the polymer backbone, has a proton conductivity of 0.091 S/cm and good insolubility in boiling water. The TGA showed that PES 60 was stable up to 272?C with a char yield of about 29%;at;900?C;under;N₂ atmosphere. To investigate the single cell performance, the catalyst coated PES 60 membrane was used and a single cell test was carried out using H₂/O₂ gases as fuel and oxidant at various temperatures. We observed that the cell performance was enhanced by increasing the cell temperature. A current density of 1400 mA/cm² at 0.60 V was obtained at 70?C.
Mohiadeen Batcha M.,Sajith Ahamed A.,Ur Rahman M. Ashiq,Janarthanan S.,Krishnan M. 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.2
The present study aims to focus on the site of fat bodies involved in the differential expression of vitellogenin protein in Bombyx mori L which is not yet fully understood. Culturing fat bodies and analyzing in in vitro and in vivo approaches made it useful to study this pattern. In Bombyx mori, L. The vitellogenin protein is 200–205 kDa and resolves at two molecular weight regions that are at 180 kDa and 42 kDa. We subject dorsal perivisceral (DPV) and ventral perivisceral fat body (VPV), haemolymph for this radio labeling cell culture and incorporation experiment. Based on our in vitro and in vivo experiments of S 35 methionine fluorography, Scanning densito metric, Western blot analysis and RT-PCR expression studies had strongly proven that the ventral perivisceral fat body is the significant and exclusive site of differential vitellogenin expression in silkworm, Bombyx mori but not in dorsal peripheral fat body tissues, haemolymph by radiolabeling studies. The present paper describes an experimental set-up based on the incubation of ventral perivisceral and dorsal perivisceral fat bodies and the measurement of vitellogenin with S 35 protein labeling incorporation method. These findings from our lab were the first report proved by in vitro and in vivo labeling experiments.
Krishnan, N.N.,Henkensmeier, D.,Jang, J.H.,Kim, H.J.,Rebbin, V.,Oh, I.H.,Hong, S.A.,Nam, S.W.,Lim, T.H. Pergamon Press ; Elsevier Science Ltd 2011 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.36 No.12
Fuel Cell operation at high temperature (e.g. 120 <SUP>o</SUP>C) and low relative humidity (e.g. 50%) remains challenging due to creep (in the case of Nafion<SUP>(</SUP>R)) and membrane dehydration. We approached this problem by filling PES 70, a sulfonated poly(ether sulfone) with a T<SUB>g</SUB> of 235 +/- 5 <SUP>o</SUP>C and a theoretical IEC of 1.68 mmol g<SUP>-1</SUP>, with 5-20% silica nano particles of 7 nm diameter and 390 +/- 40 m<SUP>2</SUP> g<SUP>-1</SUP> surface area. While simple stirring of particles and polymer solutions led to hazy, strongly anisotropic (air/glass side) and sometimes irregular shaped membranes, good membranes were obtained by ball milling. SEM analysis showed reduced anisotropy and TEM analysis proved that the nanoparticles are well embedded in the polymer matrix. The separation length between the ion-rich domains was determined by SAXS to be 2.8, 2.9 and 3.0 nm for PES 70, PES 70-S05 and Nafion<SUP>(</SUP>R) NRE 212, respectively. Tensile strength and Young's modulus increase with the amount of silica. Ex-situ in-plane proton conductivity showed a maximum for PES 70-S05 (2 mS cm<SUP>-1</SUP>). In the fuel cell (H<SUB>2</SUB>/air, 120 <SUP>o</SUP>C, <50%), it showed a current density of 173 mA cm<SUP>-2</SUP> at 0.7 V, which is 3.4 times higher than for PES 70.
D. P. Sam Solomon,V. Selladurai,A. S. Krishnan 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1
The article presents the evolution of a novel configuration of tube placements in a shell and tube heat exchanger (HX). A CFD analysis on a double cross flow arrangement of tubes reveals improved mixing of the shell-fluid which is expected to increase heat transfer. This arrangement was modified for easier manufacture and maintenance, which led to the hybrid double cross flow (HDCF) arrangement. Experiments were carried out in the HDCFHX, for parallel and counter flows, to compare its performance against the conventional staggered arrangement. The HDCFHX comprises composite bundles of three and four tubes. The threetube bundle is arranged in a staggered manner to themselves and orthogonal to the four-tube bundle. Ambient air at of 32 °C was used as the shell-fluid for Reynolds number ranging from 500 to 1000, for a fixed flow rate of 0.6 kg/min of water entering the tubes at 85 °C. This arrangement was observed to enhance the heat transfer with relatively lesser increase in pressure drop. The HDCFHX gave a significant improvement in heat transfer rate per pressure drop of 17 % to 38 %, vis-à-vis the conventional staggered arrangement in the parallel mode. The counter flow mode overly exhibited a similar trend, wherein the increase in this ratio varied from 8.5 % to 27.5 %.
Krishnan, N.,Chaudhuri, A.,Sengupta, A.K.,Chandra, A.K.,Sen, S.K.,Saratchandra, B. Korean Society of Sericultural Science 2001 International Journal of Industrial Entomology Vol.2 No.2
The influence of baculovirus Bombyx mori Nuclear Polyhedrosis virus (BmNPV) infection on intermediary metabolic pathways in silkworm Bombyx mori L. was investigated. Studies revealed that NADP-linked malate dehydrogenase activity in hemolymph of infected silkworms at 96 hrs post infection (p.i.) with visible symptoms of infection was enhanced in comparison to healthy larvae of the same age. Also, NADP-dependent MDH activity was significantly lower in fat body cytosol of infected larvae at 96 hrs p.i. when compared to healthy larvae. Similarly, some biometabolic parameters like growth, protein content and cholesterol titer were observed to be influenced by baculovirus infection. While the growth of infected larvae was significantly retardedi protein content was also drastically reduced in both hemolymph and fat body tissues. Cholesterol titers however, was enhanced in infected larvae. The results observed herein point to a significant change in the normal biochemical and biometabolic pathways required for growth and development following BmNPV infection.
V. S. MUTHUKUMAR,J. K. KIRAN,JASON REPPERT,R. SATYAJIT,VAMSI KRISHNA,G. NAGESHWAR RAO,S. SIVA RAMA KRISHNAN,S. SIVA SANKARA SAI,K. VENKATARAMANIAH,A. M. RAO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2008 NANO Vol.3 No.3
Saturable absorbers and optical limiters have contrary optical transmission properties. We report observations of simultaneous occurrence of both these effects in a nickel sulphide nanoparticle (average dia. ~5 nm) solution and a simultaneous quantitative measurement of both. Intensity dependent nonlinear transmission studies carried out using a 7 ns Nd:YAG laser at 532 nm by the Z-scan method, revealed efficient optical limiting in nickel sulphide nanoparticle suspensions. Induced nonlinear optical scattering was identified to be the mechanism of optical limiting, and absorption at 532 nm was found to saturate. A modification of the conventional Z-scan implementation led to the retrieval of the saturation intensity which is otherwise overshadowed by very strong nonlinear scattering.
Chaudhuri, A.,Krishnan, N.,Roy, G.C.,Sengupta, A.K.,Sen, S.K.,Saratchandra, B. Korean Society of Sericultural Science 2001 International Journal of Industrial Entomology Vol.2 No.2
Variations in protein and nucleic acid concentrations were observed in 24 hrs old eggs and hatched larvae of Nistari strain, Bombyx mori, exposed to starvation. Three starvation treatments of 24,48 and 60 hrs were given separately from 0 hr old fifth instar larvae. Biochemical variations were studied in the resultant hatched larvae of one time starved parent, while the eggs obtained from parents receiving starvation in two successive generations were considered for the study. In hatched larvae, protein levers in 24 hrs starvation groups remained significantly higher over control (never starved) while the same was found to be lower in 48 and 60 hrs starvation individuals. The RNA concentration remained significantly higher in all the treated lots. However, DNA content was not found to be significantly altered in hatched larvae after exposure to feeding stress. Protein, RNA and DNA concentration of 24 hrs old eggs produced by all the starved groups of Nistari, which had deceived two consecutive starvation during parental generations, showed higher concentrations of these biomolecules over control. Hence, starvation induced alterations in protein and nucleic acids in eggs and hatched Iarvae are indicative of a preparatory phase adopted by the insect to acclimatise itself and its progeny to stress situations.
Cigarette smoke and related risk factors in neurological disorders: An update
G, S.B.A.,Choi, S.,Krishnan, J.,K, R. Masson Pub. USA, Inc 2017 Biomedicine & pharmacotherapy Vol.85 No.-
<P>Cigarette smoking is known to be harmful to health, and is considered the main cause of death worldwide, especially in India. Among the well-distinguished diseases related to smoking are, chronic obstructive pulmonary disease, oral and peripheral cancers, and cardiovascular complications. However, the impact of cigarette smoking on neurocognitive and neuropathological effects, including anxiety, Alzheimer's disease, Parkinson's disease, ischemic stroke, and blood-brain barrier dysfunction, still remains unclear. Cigarette smoke consists of more than 4500 toxic chemicals that combine to form free radicals, which lead to oxidative stress-associated neurological disorders. Herein, we discuss the role of antioxidant agents in delaying or attenuating disease complications. In addition, in this review, we discuss the neuropathological effect of cigarette smoke and its interference in neurodegeneration. (C) 2016 Elsevier Masson SAS. All rights reserved.</P>
Saha, A. K.,Chaudhuri, A.,Krishnan, N.,Sengupta, A. K.,Shamsuddin, M.,Sen, S. K.,Saratchandra, B. 한국잠사학회 1998 한국잠사곤충학회지 Vol.40 No.1
One indigenous polyvoltine strain (Nistari) and two bivoltine strains viz. P5, and NB18, along with one bivoltine hybrid (P5 X NB18) were subjected for studies on the differences on some physiologically important biomolecules like protein, nucleic acids and cholesterol. Ovarian protein and RNA content remained significantly high in the bivoltine races and their hybrid over multivoltine breed, while, DNA and cholesterol content remained significantly low in all the breeds and the hybrid as compared to Nistari strain. However, the ovarian weight was higher in both the bivoltine breeds and their hybrid than that of Nistnri. Higher ovarian weight together with more protein and RNA concentrations reflect the preparatory phase for production of diapausing eggs by the bivoltines. This is indicated by the production of more number of eggs by the bivoltine silkmoths and their hybrid. The variations in biochemical parameters studied herein, thus establish a distinct difference in the overt reproductive physioiogy between multivoltine and bivoltine silkworms.