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Mohanan N. Madana,Krishnan N.,Mitra P.,Das N. K.,Saratchandra B.,Haldar D. P. Korean Society of Sericultural Science 2005 International Journal of Industrial Entomology Vol.11 No.2
Impact of microsporidian infection and season on reproductive potential of Bombyx mori L. was investigated in the laboratory. Microsporidian infection significantly (P<0.01) reduced fecundity and hatching and increased sterility and mortality of eggs. Among the microsporidia, Nosema sp. 2 infected silkworm produced eggs with least fecundity and hatching percent as well as highest dead and sterile eggs followed by Nosema sp. 1 and N. bombycis. Microsporidia, in general, significantly reduced fecundity and hatching percent of eggs and increased number of dead and sterile eggs in all the three seasons except N. bombycis in July - August (S3) and Nosema sp. 2 in January February (S1). Since, seed production is the anchor sheet of mulberry sericulture, coefficient of egg lying is considered as an important aspect and the industry quite often facing shortage of disease free layings. The present study indicates that B. mori is more susceptible to microsporidia during S2 followed by S3 and S1 and Nosema sp2. is most virulent followed by Nosema spl. and N. bombycis.
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.
Alkyl chain modified sulfonated poly(ether sulfone) for fuel cell applications
Krishnan, N.N.,Henkensmeier, D.,Jang, J.H.,Kim, H.J.,Ha, H.Y.,Nam, S.W. Pergamon Press ; Elsevier Science Ltd 2013 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.38 No.6
A new alkyl chain modified sulfonated poly(ether sulfone) (mPES) was synthesized and formed into membranes. The MEAs were tested in the PEMFC and evaluated systematically in the DMFC by varying the methanol concentration from 0.5 to 5.0 M at 60 <SUP>o</SUP>C and 70 <SUP>o</SUP>C. The synthesized mPES copolymer has been characterized by nuclear magnetic resonance spectroscopy, fourier transform infrared spectroscopy, thermogravimetric analysis, and gel permeation chromatography. The proton conductivity of the resulting membrane is higher than the threshold value of 10<SUP>-2</SUP> S cm<SUP>-1</SUP> at room temperature for practical PEM fuel cells. The membrane is insoluble in boiling water, thermally stable until 250 <SUP>o</SUP>C and shows low methanol permeability. In the H<SUB>2</SUB>/air PEMFC at 70 <SUP>o</SUP>C, a current density of 600 mA cm<SUP>-2</SUP> leads to a potential of 637 mV and 658 mV for 50 μm thick mPES 60 and Nafion NRE 212, respectively. In the DMFC, mPES 60's methanol crossover current density is 4 times lower than that for Nafion NRE 212, leading to higher OCV values and peak power densities. Among all investigated conditions and materials, the highest peak power density of 120 mW cm<SUP>-2</SUP> was obtained with an mPES 60 based MEA at 70 <SUP>o</SUP>C and a methanol feed of 2 M.
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.
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.
Sulfonated poly(ether sulfone)-based catalyst binder for a proton-exchange membrane fuel cell
Krishnan, N. Nambi,Kim, Hyoung-Juhn,Jang, Jong Hyun,Lee, Sang-Yeop,Cho, EunAe,Oh, In-Hwan,Hong, Seong-Ahn,Lim, Tae-Hoon Wiley Subscription Services, Inc., A Wiley Company 2009 Journal of applied polymer science Vol.113 No.4
<P>Sulfonated poly(ether sulfone) copolymer (PES 60) and its partially fluorinated analogue (F-PES 60) were synthesized via the nucleophilic aromatic polycondensation of commercially available monomers to make a polymer electrolyte membrane and a binding material in the electrodes of a membrane–electrode assembly (MEA). PES 60 and F-PES 60 showed proton conductivities of 0.091 and 0.094 S/cm, respectively, in water at room temperature. The copolymer was dissolved in the mixture of alcohol and water to get a 1 wt % binder solution. A catalyst slurry was prepared with the copolymer solution and sprayed on the copolymer (PES 60 or F-PES 60) membrane to obtain a MEA. Both PES 60 and F-PES 60 based MEAs were fabricated with different amounts of their binder in the electrodes to examine the effect of the copolymer binder in the catalyst layer on the fuel cell performance. The MEA with 2 wt % copolymer binder in the electrodes showed the best fuel cell performance. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009</P>
Fabrication of MEA with hydrocarbon based membranes using low temperature decal method for DMFC
Krishnan, N.N.,Prabhuram, J.,Hong, Y.T.,Kim, H.J.,Yoon, K.,Ha, H.Y.,Lim, T.H.,Kim, S.K. Pergamon Press ; Elsevier Science Ltd 2010 International journal of hydrogen energy Vol.35 No.11
The membrane electrode assembly (MEA) with hydrocarbon (HC) based membranes made by a low temperature decal method has been investigated for the direct methanol fuel cells (DMFCs). The conventional low temperature decal (LTD) transfer method (comprised of three layers; viz., carbon, Nafion bonded electrodes and outer ionomer layers over the decal Teflon substrates) meant for the MEAs made of Nafion type membranes is suitably modified to use with hydrocarbon (HC) based membranes. The modification of conventional LTD method is effected by means of modulating the three-layered structure and optimizing other parameters to facilitate complete transfer of catalyst layers onto the HC membranes. The MEAs prepared by the modified LTD method have yielded 21 % higher DMFC performance compared to that of the MEAs produced by conventional LTD method. The structure and electrochemical properties of the MEAs have been analyzed by the field-emission scanning electron microscopy (FE-SEM) and the electrochemical impedance spectroscopy (EIS).
An Intelligent 2D Secret Share Construction using Visual Cryptography for Secure Transmission
( N. Rajesh Kumar ),( R. Bala Krishnan ),( G. Manikandan ),( N. R. Raajan ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.7
Data Security is the most challenging area in Internet communication, where most of the secret sharing schemes are proposed for binary images. But still it lacks in providing security for data communication, especially in image transmission. Traditional visual cryptography scheme generate meaningless diwies and the reconstruction phase leads to quality degradation over the secret image. In this work, an intelligent two dimensional secret share construction scheme is proposed. A secret image is expanded into n diwies with the choice of scheme selection. By Stacking all the qualified diwies to revert the secret image without content loss and less than s* - 1 shares could not reveal any information about the secret image. The experimental results emphasize that the proposed secret share scheme is highly secured for image transmission.