The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Tae June Kang - One of the best experts on this subject based on the ideXlab platform.
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high efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes
Nature Communications, 2016Co-Authors: Hyeongwook Im, Hyelynn Song, Jongho Choi, Jaesung Park, Raquel Ovallerobles, Hee Doo Yang, Kenneth D Kihm, Ray H Baughman, Tae June KangAbstract:Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m−2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. Here, the authors fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application.
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high efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes
Nature Communications, 2016Co-Authors: Tae Woo Kim, Hyelynn Song, Jongho Choi, Jaesung Park, Raquel Ovallerobles, Hee Doo Yang, Kenneth D Kihm, Ray H Baughman, Hyun Jung Lee, Tae June KangAbstract:Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m(-2) is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated.
Seiji Akimoto - One of the best experts on this subject based on the ideXlab platform.
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light Harvesting Strategy during co2 dependent photosynthesis in the green alga chlamydomonas reinhardtii
Journal of Physical Chemistry Letters, 2018Co-Authors: Yoshifumi Ueno, Ginga Shimakawa, Chikahiro Miyake, Seiji AkimotoAbstract:To maximize the efficiency of photosynthesis, photosynthetic organisms must properly balance their light-Harvesting ability and CO2 utilization. However, the molecular mechanisms of light Harvesting under various CO2 conditions remain unclear. To reveal these mechanisms, we performed new analysis on cells of the green alga Chlamydomonas reinhardtii under different CO2 conditions. The analysis combines three kinds of fluorometries: pulse-amplitude modulated fluorescence, steady-state fluorescence with absolute intensity, and time-resolved fluorescence. Under low CO2 conditions, the main regulatory mechanism was migration of a light-Harvesting chlorophyll–protein complex (LHC) II from photosystem (PS) II to PSI. However, under CO2-deficient conditions with carbon supplementation, some of the LHCII separated from the PSI and aggregated with quenching. These different light-Harvesting abilities of LHCII may play an important role in the regulation of light Harvesting in C. reinhardtii under various CO2 condit...
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Control Mechanism of Excitation Energy Transfer in a Complex Consisting of Photosystem II and Fucoxanthin Chlorophyll a/c‑Binding Protein
2015Co-Authors: Ryo Nagao, Makio Yokono, Tatsuya Tomo, Seiji AkimotoAbstract:Fucoxanthin chlorophyll (Chl) a/c-binding protein (FCP) is a unique light-Harvesting antenna in diatoms, which are photosynthesizing algae ubiquitous in aquatic environments. However, it is unknown how excitation energy is trapped and quenched in a complex consisting of photosystem II and FCP (PSII–FCPII complex). Here, we report the control mechanism of excitation energy transfer in the PSII–FCPII complexes isolated from a diatom, Chaetoceros gracilis, as revealed by picosecond time-resolved fluorescence spectroscopy. The results showed that Chl-excitation energy is harvested in low-energy Chls near/within FCPII under the 77 K conditions, whereas most of the energy is trapped in reaction center Chls in PSII under the 283 K conditions. Surprisingly, excitation energy quenching was observed in a part of PSII–FCPII complexes with the time constants of hundreds of picosecond, thus indicating the large contribution of FCPII to energy trapping and quenching. On the basis of these results, we discuss the light-Harvesting Strategy of diatoms
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control mechanism of excitation energy transfer in a complex consisting of photosystem ii and fucoxanthin chlorophyll a c binding protein
Journal of Physical Chemistry Letters, 2014Co-Authors: Ryo Nagao, Makio Yokono, Tatsuya Tomo, Seiji AkimotoAbstract:Fucoxanthin chlorophyll (Chl) a/c-binding protein (FCP) is a unique light-Harvesting antenna in diatoms, which are photosynthesizing algae ubiquitous in aquatic environments. However, it is unknown how excitation energy is trapped and quenched in a complex consisting of photosystem II and FCP (PSII-FCPII complex). Here, we report the control mechanism of excitation energy transfer in the PSII-FCPII complexes isolated from a diatom, Chaetoceros gracilis, as revealed by picosecond time-resolved fluorescence spectroscopy. The results showed that Chl-excitation energy is harvested in low-energy Chls near/within FCPII under the 77 K conditions, whereas most of the energy is trapped in reaction center Chls in PSII under the 283 K conditions. Surprisingly, excitation energy quenching was observed in a part of PSII-FCPII complexes with the time constants of hundreds of picosecond, thus indicating the large contribution of FCPII to energy trapping and quenching. On the basis of these results, we discuss the light-Harvesting Strategy of diatoms.
Tomas Polivka - One of the best experts on this subject based on the ideXlab platform.
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spectroscopy of the peridinin chlorophyll a protein insight into light Harvesting Strategy of marine algae
Archives of Biochemistry and Biophysics, 2007Co-Authors: Tomas Polivka, Roger G Hiller, Harry A FrankAbstract:An important component of the photosynthetic apparatus is a light-Harvesting system that captures light energy and transfers it efficiently to the reaction center. Depending on environmental conditions, photosynthetic antennae have adopted various strategies for this function. Peridinin-chlorophyll-a protein (PCP) represents a unique situation because, unlike other antenna systems which have a preponderance of chlorophyll, it has the carotenoid, peridinin, as its major pigment. The key structural feature of peridinin is a conjugated carbonyl group. Owing to the presence of this group, an intramolecular charge-transfer excited state is formed in peridinin which exhibits different excited state spectra and dynamics depending on the polarity of the environment. The charge-transfer state also facilitates energy transfer between peridinin and chlorophyll-a in PCP. This review summarizes results of spectroscopic investigations of PCP in the past few years, emphasizing the specific light-Harvesting Strategy developed by marine photosynthetic organisms utilizing carbonyl-containing carotenoids in their antenna complexes.
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carotenoid to chlorophyll energy transfer in the peridinin chlorophyll a protein complex involves an intramolecular charge transfer state
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Donatas Zigmantas, Roger G Hiller, Villy Sundstrom, Tomas PolivkaAbstract:Carotenoids are, along with chlorophylls, crucial pigments involved in light-Harvesting processes in photosynthetic organisms. Details of carotenoid to chlorophyll energy transfer mechanisms and their dependence on structural variability of carotenoids are as yet poorly understood. Here, we employ femtosecond transient absorption spectroscopy to reveal energy transfer pathways in the peridinin-chlorophyll-a-protein (PCP) complex containing the highly substituted carotenoid peridinin, which includes an intramolecular charge transfer (ICT) state in its excited state manifold. Extending the transient absorption spectra toward near-infrared region (600-1800 nm) allowed us to separate contributions from different low-lying excited states of peridinin. The results demonstrate a special light-Harvesting Strategy in the PCP complex that uses the ICT state of peridinin to enhance energy transfer efficiency.
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carotenoid to chlorophyll energy transfer in the peridinin chlorophyll a protein complex involves an intramolecular charge transfer state
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Donatas Zigmantas, Roger G Hiller, Villy Sundstrom, Tomas PolivkaAbstract:Carotenoids are, along with chlorophylls, crucial pigments involved in light-Harvesting processes in photosynthetic organisms. Details of carotenoid to chlorophyll energy transfer mechanisms and their dependence on structural variability of carotenoids are as yet poorly understood. Here, we employ femtosecond transient absorption spectroscopy to reveal energy transfer pathways in the peridinin–chlorophyll-a–protein (PCP) complex containing the highly substituted carotenoid peridinin, which includes an intramolecular charge transfer (ICT) state in its excited state manifold. Extending the transient absorption spectra toward near-infrared region (600–1800 nm) allowed us to separate contributions from different low-lying excited states of peridinin. The results demonstrate a special light-Harvesting Strategy in the PCP complex that uses the ICT state of peridinin to enhance energy transfer efficiency.
Hyelynn Song - One of the best experts on this subject based on the ideXlab platform.
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high efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes
Nature Communications, 2016Co-Authors: Hyeongwook Im, Hyelynn Song, Jongho Choi, Jaesung Park, Raquel Ovallerobles, Hee Doo Yang, Kenneth D Kihm, Ray H Baughman, Tae June KangAbstract:Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m−2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. Here, the authors fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application.
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high efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes
Nature Communications, 2016Co-Authors: Tae Woo Kim, Hyelynn Song, Jongho Choi, Jaesung Park, Raquel Ovallerobles, Hee Doo Yang, Kenneth D Kihm, Ray H Baughman, Hyun Jung Lee, Tae June KangAbstract:Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m(-2) is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated.
Jongho Choi - One of the best experts on this subject based on the ideXlab platform.
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high efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes
Nature Communications, 2016Co-Authors: Hyeongwook Im, Hyelynn Song, Jongho Choi, Jaesung Park, Raquel Ovallerobles, Hee Doo Yang, Kenneth D Kihm, Ray H Baughman, Tae June KangAbstract:Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m−2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. Here, the authors fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application.
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high efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes
Nature Communications, 2016Co-Authors: Tae Woo Kim, Hyelynn Song, Jongho Choi, Jaesung Park, Raquel Ovallerobles, Hee Doo Yang, Kenneth D Kihm, Ray H Baughman, Hyun Jung Lee, Tae June KangAbstract:Conversion of low-grade waste heat into electricity is an important energy Harvesting Strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m(-2) is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated.
