| 1. |
- Keable, Stephen M., et al.
(author)
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Room temperature XFEL crystallography reveals asymmetry in the vicinity of the two phylloquinones in photosystem I
- 2021
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In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- Photosystem I (PS I) has a symmetric structure with two highly similar branches of pigments at the center that are involved in electron transfer, but shows very different efficiency along the two branches. We have determined the structure of cyanobacterial PS I at room temperature (RT) using femtosecond X-ray pulses from an X-ray free electron laser (XFEL) that shows a clear expansion of the entire protein complex in the direction of the membrane plane, when compared to previous cryogenic structures. This trend was observed by complementary datasets taken at multiple XFEL beamlines. In the RT structure of PS I, we also observe conformational differences between the two branches in the reaction center around the secondary electron acceptors A1A and A1B. The π-stacked Phe residues are rotated with a more parallel orientation in the A-branch and an almost perpendicular confirmation in the B-branch, and the symmetry breaking PsaB-Trp673 is tilted and further away from A1A. These changes increase the asymmetry between the branches and may provide insights into the preferential directionality of electron transfer.
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| 2. |
- Arul, A.J, et al.
(author)
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Reliability analysis of safety grade decay heat removal system of Indian prototype fast breeder reactor
- 2006
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In: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549. ; 33:2, s. 180-188
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Journal article (peer-reviewed)abstract
- The 500MW Indian pool type Prototype Fast Breeder Reactor (PFBR), is provided with two independent and diverse Decay Heat Removal (DHR) systems viz., Operating Grade Decay Heat Removal System (OGDHRS) and Safety Grade Decay Heat Removal System (SGDHRS). OGDHRS utilizes the secondary sodium loops and Steam–Water System with special decay heat removal condensers for DHR function. The unreliability of this system is of the order of 0.1–0.01. The safety requirements of the present generation of fast reactors are very high, and specifically for DHR function the failure frequency should be less than 1E-7/ry. Therefore, a passive SGDHR system using four completely independent thermo-siphon loops in natural convection mode is provided to ensure adequate core cooling for all Design Basis Events. The very high reliability requirement for DHR function is achieved mainly with the help of SGDHRS. This paper presents the reliability analysis of SGDHR system. Analysis is performed by Fault Tree method using "CRAFT" software developed at Indira Gandhi Centre for Atomic Research. This software has special features for compact representation and CCF analysis of high redundancy safety systems encountered in nuclear reactors. Common Cause Failures (CCF) are evaluated by beta-factor method. The reliability target for SGDHRS arrived from DHR reliability requirement and the ultimate number of demands per year (7/y) on SGDHRS is that the failure frequency should be <=1.4E-8/de. Since it is found from the analysis that the unreliability of SGDHRS with identical loops is 5.2E-6/de and dominated by leak rates of components like AHX, DHX and sodium dump and isolation valves, options with diversity measures in important components were studied. The failure probability of SGDHRS for a design consisting of 2 types of diverse loops (Diverse AHX, DHX and sodium dump and isolation valves) is 2.1E-8/de, which practically meets the reliability requirement.
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| 4. |
- Aydin, Juhanes, et al.
(author)
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Synthesis and catalytic application of chiral 1,1'-Bi-2-naphthol- and biphenanthrol-based pincer complexes: selective allylation of sulfonimines with allyl stannane and allyl trifluoroborate.
- 2007
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In: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 72:13, s. 4689-4697
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Journal article (peer-reviewed)abstract
- New easily accessible 1,1'-bi-2-naphthol- (BINOL-) and biphenanthrol-based chiral pincer complex catalysts were prepared for selective (up to 85% enantiomeric excess) allylation of sulfonimines. The chiral pincer complexes were prepared by a flexible modular approach allowing an efficient tuning of the selectivity of the catalysts. By employment of the different enantiomeric forms of the catalysts, both enantiomers of the homoallylic amines could be selectively obtained. Both allyl stannanes and allyl trifluoroborates can be employed as allyl sources in the reactions. The biphenanthrol-based complexes gave higher selectivity than the substituted BINOL-based analogues, probably because of the well-shaped chiral pocket generated by employment of the biphenanthrol complexes. The enantioselective allylation of sulfonimines presented in this study has important implications for the mechanism given for the pincer complex-catalyzed allylation reactions, confirming that this process takes place without involvement of palladium(0) species.
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| 5. |
- Das, Santanu, et al.
(author)
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Comparative study of bioenzyme production using submerged fermentation on different agricultural wastes on ligninase producing from wood rot fungi isolated from Pushpagiri and Brahmagiri Hills of Karnataka
- 2020
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In: Journal of Advanced Research in Dynamical and Control Systems. - : Institute of Advanced Scientific Research. - 1943-023X. ; 12:7 Special Issue, s. 1562-1569
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Journal article (peer-reviewed)abstract
- A total of 132 White rot fungus were isolated from the wood bark samples, collected from the different locations in the Western Ghats region of Karnataka and screened for Ligninolytic enzyme production. Ten strains exhibiting maximum activity numbered 30, 40, 41, 61, 76, 86, 104, 113, 123 and 124 were further screened under submerged fermentation using agricultural wastes for enzyme production activity. Among the four substrates used (Sawdust, Paddy straw, Pongamia leaf, Kitchen Vegetable waste), highest lignin peroxidase activity was seen in Pongamia with strain 75 (0.766 U/ml) and minimum was in Paddy straw with strain 124(0.003 U/ml). Highest Manganese Peroxide content was seen in sawdust with strain 40 (1.014 U/ml) and minimum was in vegetable waste strain 75 (0.150 U/ml). Highest laccase activity was in Pongamia leafwith strain 123 (0.375 U/ml) and lowest was in Paddy straw strain (75)(0.012 U/ml).Highest versatile peroxidase activity was observed in Pongamia strain 113(0.504 U/ml) and lowest in Paddy straw strain 61 (0.023 U/ml). Cellulase content was highest with Pongamia using strain 41 (0.032 U/ml)and lowest in Paddy straw with strains61, 104, 113, 124 (0.003 U/ml).Highest Protein content was present in Pongamia degradation with strain 104(0.246 U/ml) and lowest was in Paddy straw with strain 113 (0.059 U/ml).The maximum enzyme activity of laccase by wood rot fungal strains 30, 40, 41, 61, 76, 86, 104, 113, 123 and 124 strains were obtained on the 8th day of fermentation wherein Manganese peroxidase and lignin peroxidase showed the highest activity on the 10th day of fermentation.
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| 6. |
- Das, Santanu, et al.
(author)
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Optimization of biofuel production by molecular characterization of ligninase enzyme isolated from wood rot fungi in Pushpagiri and Brahmagiri Hills in Karnataka by using RAPD molecular markers
- 2020
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In: Journal of green engineering. - : Alpha Publishers. - 1904-4720 .- 2245-4586. ; 10:6, s. 2560-2597
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Journal article (peer-reviewed)abstract
- Wood rot fungi are one of the major degraders in the biosphere that help in degrading most of the plant origin polymers like cellulose, hemicellulose and lignin. Lignin is the second most abundant aromatic compound found in plant cell that holds up cellulose and hemicellulose. There is a lot of emphasis that is being put on the fungal degradation of lignin using wood and other lignocellulosic as a renewable source in the production of chemicals, paper products, feeds and fuels and the use of fungi as one of the most potent sources of degrading organisms. In the present study, screening for lignin degrading enzymes were done with 132 isolates and the maximum enzyme producing strains of 10 wood rot fungi samples were taken for molecular characterization using RAPD molecular markers.Isolation of genomic DNA of the 10 wood rot fungi samples was done using phenolchloroform method and quantified on agarose gel. The obtained genomic DNA was further subjected tocharacterization using RAPD-PCR method with 06 random primers OPA2, OPA5, OPA7, OPA8, OPD3 and OPC2. The amplified PCR products were analyzed by Agarose Gel Electrophoresis and were observed under UV Transilluminator. Analysis of the base pairs of the bands was done by Bio-Rad Gel Doc system.A total of 172 fragments were generated in the 10 isolates with 6 primers. Dendrogram analyses of the gels were done which gave a close relation of each DNA samples. The results indicate that some strains were genetically more similar and few diverse. The current study shows samples 30, 40, 41, 113 and 124 are genetically closely related.
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