731 |
Optimization of accelerator and brake in photosynthetic electron transport / 光合成電子伝達におけるアクセルとブレーキの最適化Leonardo, Basso 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第23048号 / 理博第4725号 / 新制||理||1677(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 鹿内 利治, 准教授 竹中 瑞樹, 教授 長谷 あきら / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
|
732 |
Design and Synthesis of Bismuth-based Layered Oxychloride Photocatalysts for Visible-Light-Driven Water Splitting / 可視光水分解のためのビスマス系層状酸塩化物光触媒の設計と合成Ozaki, Daichi 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23216号 / 工博第4860号 / 新制||工||1759(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 阿部 竜, 教授 陰山 洋, 教授 藤田 晃司 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
|
733 |
Genotypic variation in water use efficiency, gaseous exchange and yield of four cassava landraces grown under rainfed conditions in South AfricaMalele, Kgetise Petros 20 August 2020 (has links)
MSCAGR (Plant Production) / Department of Plant Production / Agricultural production under rain-fed conditions is largely dependent on the availability of water stored in the soil during rainfall events. The production of cassava (Manihot esculenta Crantz) under rain-fed conditions in the north-eastern part of South Africa is constrained by low and erratic rainfall events. Improving cassava production in the area requires the use of cassava varieties which are efficient in the use of limited soil moisture. The current climate change and increasing population growth on the planet will place more pressure on agriculture to produce more food using less water. Therefore, previously under-researched and underutilised crop like cassava could be used to bridge the food gap in the future. Although the crop currently occupies low levels of utilisation in South Africa and it is cultivated by smallscale farmers in the Low-veld of Mpumalanga, Limpopo and Kwazulu-Natal provinces using landraces with no improved varieties available in the country. Information on the actual pattern of water extraction, water use and water use efficiency of cassava landraces grown in the dry environments of South Africa is limited. Therefore, the objective of the study was to determine the differences in water use efficiency, gaseous exchange and yield among four cassava landraces grown under rain-fed conditions.
Two field experiments were conducted during the wetter (2016/2017) and drier (2017/2018) cropping season at the University of Venda's experimental farm. The trials were laid in a Randomized Complete Block Design (RCBD) consisting of four cassava landraces (ACC#1, ACC#2, ACC#3, and ACC#4) replicated three times. Mature cassava stem cuttings of 30 cm long, were planted manually at a spacing of 1 m x 1 m in both seasons. Each experimental unit consisted of six plant rows of 6 m length (36 m2) and 8 rows of 8 m length (64 m2) in the 2016/17 and 2017/2018 cropping season, respectively. The experiments were under rain-fed conditions without fertilizer additions and the plots were kept weed-free throughout the experimental period.
Data collected in the field included soil moisture content, gaseous exchange parameters (net leaf ܥܱଶ uptake, stomatal conductance, and intracellular carbon dioxide concentration), chlorophyll content index (CCI), maximum photochemical quantum yield of PSII (Fv/Fm), effective quantum yield of PSII (ФPSII) and photosynthetic active radiation (PAR). Yield and yield components (root length (cm), root girth (cm), number of storage roots and mean root weight (g plant-1), root yield and aboveground biomass), as well as water use efficiency (WUE), were determined at harvest. Soil moisture content was measured at seven-day interval from sowing until harvest using a neutron probe. Soil moisture data were used to determine crop water use using the water balance approach.
There was no variation in the root yield and yield components amongst the landraces in 2017/2018 cropping season but, genotypes affected aboveground biomass, root girth, number of roots per plant and root yield in 2016/2017 cropping season. There was a significant difference (P<0.01) in number of roots (per plant) 81% and 62% greater in ACC#3 and ACC#2 (6.7 & 6.0, respectively) compared with ACC#1 and ACC#4, which both recorded 4 roots per plant. Similarly, root girth was greater in ACC#3 (17.8 cm) and ACC#2 (18.2 cm) compared to ACC#1 (14.1 cm) and ACC#4 (12.9 cm), which were statistically the same. In contrast, total biomass (P<0.01) and root yield (P<0.05) were greater in ACC#3 (20.7 and 11.9 t ha-1, respectively) and ACC#1 (22.0 and 11.3 t ha-1, respectively) compared to ACC#2 and ACC#4 with root yields of 10.2 and 9.5 t ha-1, biomass of 17.1 and 16.3 t ha-1, respectively. Although the genotype x cropping season interaction did not affect root yield and yield components, root yield (by 33.8%; 2.7 t ha-1) and yield components were greater in the wetter compared to the drier season as expected. Water use efficiency of root yield (WUErt) and water use efficiency of biomass production (WUEb) varied with landraces in season I from 37.0 kg ha-1 mm-1 (ACC#4) to 46.60 kg ha-1 mm-1 (ACC#3), and between 71.30 kg ha-1 mm-1 (ACC#2) and 86.0 kg ha-1 mm-1 (ACC#1), respectively.
Landraces did not differ in their water use and soil moisture extraction in both seasons but differed in season. However, there was a significant positive correlation between water use efficiency of root yield (WUErt) (0.963***) and water use efficiency of biomass production (WUEb) (0.847***). WUE of biomass production was greater in the drier than the wetter season partly because of dry matter accumulation per evapotranspiration within the landraces. Photosynthesis did not vary with landraces, however, stomatal conductance varied with landraces from 0.08 mmol m-2 s-1 (ACC#4) to 0.2 mmol m-2 s-1 (ACC#2). In contrast, ACC#1 and ACC#3 recorded the same value of stomatal conductance, which is 0.1 mmol m-2 s-1. The effective quantum yield of PSII photochemistry (ΦPSII) did not vary with landraces but the maximum photochemical quantum yield of PSII (Fv/Fm) varied with landraces from 0.652 (ACC#4) to 0.792 (ACC#3) in season II. The proportion of intercepted radiation was affected by landraces in 2017/2018 cropping season. Highest proportion of intercepted radiation was observed in ACC#3 and the lowest in ACC#2. Proportion of intercepted radiation varied with landraces from 22.62% (ACC#2) to 86.45% (#ACC#3). There were significant genotypic variations in chlorophyll content recorded in both season. Chlorophyll content varied with landraces from 33.1 CCI (ACC4) to 55.4 CCI (#ACC3) in the 2016/2017, and in 2017/2018 cropping season chlorophyll content varied with landraces from 36.9 CCI (ACC4) to 78.7 CCI (#ACC3). The highest genotypic variation in chlorophyll content was observed in ACC#3, whilst the lowest chlorophyll content was recorded in ACC#4 in both seasons. / NRF
|
734 |
Cool Temperature Effects on Productivity and Photosynthesis of Two Biomass Fuel Species: Switchgrass (Panicum virgatum) and Miscanthus (Miscanthus x giganteus)Mitchell, Jackson Lee Bean 14 January 2013 (has links)
The world\'s highest yielding crops are C4 plants due to their higher water use efficiency, nitrogen use efficiency, and productivity compared with C3 plants. With an increasing demand for renewable resources as a result of the decreasing global supplies of fossil fuels, we need to improve our understanding of the limitations of biomass fuel feedstock to improve yields and better satisfy energy requirements. The ability to attain the goal feedstock production in the US is limited by available arable land and cool temperatures. This study investigates the effects of cool temperatures on the productivity and photosynthesis of the two species with the highest potential for feedstock production in the US: switchgrass (Panicum virgatum) cv. Alamo and miscanthus (Miscanthus × giganteus). At 14/12"C and a 14/10 hour light/dark photoperiod, switchgrass showed lower productivity and light saturated photosynthetic rates (Amax=10.3 "mol m-2s-1) compared with 28/25"C and the same photoperiod (Amax=18.8 "mol m-2s-1). Miscanthus has demonstrated cold tolerance in previous studies, and here showed no significant decrease in the productivity or photosynthetic rates in cool, compared with warm, growing conditions (Amax=8.2 "mol m-2s-1 and 7.0 "mol m-2s-1 for warm and cool conditions, respectively). Also, this study examines the potential limitations of C4 photosynthesis by the enzyme pyruvate phosphate dikinase (PPDK) under the same cool conditions, transgenic switchgrass cv. Alamo were created with the insertion of the miscanthus PPDK gene. Productivity and photosynthetic responses of the transgenic plants were evaluated in cool and warm growth temperatures. Of the two transgenic events tested here, line S(1) displayed cold tolerance, as seen in no loss of both carboxylation efficiency and the ratio of CO2 assimilation to electron transport (Asat/Jmax). These results indicate that PPDK may pose a significant limitation to C4 photosynthesis in cool conditions and there is a possibility that cold season photosynthesis of switchgrass cv. Alamo could be improved. / Master of Science
|
735 |
Electron and multielectron reaction characterizations in molecular photosystems by laser flash photolysis, towards energy production by artificial photosynthesis / Caractérisation des processus électroniques et multi-électroniques par spectroscopies laser résolues en temps dans des photosystemes moleculaires, vers la production de fuel solaire par photosynthèse artificielleTran, Thu-Trang 27 September 2019 (has links)
La demande énergétique de l’humanité augmente rapidement et ne montre aucun signe de ralentissement. Parallèlement à cette problématique, l'utilisation abusive de combustibles fossiles est l'une des principales causes d'augmentation de la concentration de CO₂ dans l'atmosphère. Ces problèmes doivent être résolus en termes de limitation des émissions de CO₂ et de recherche de sources d'énergie renouvelables pour remplacer les combustibles fossiles. De nos jours, l’énergie solaire est l’une des sources d’énergie renouvelables les plus efficaces. La conversion de l'énergie de la lumière solaire en électricité dans le photovoltaïque ou en énergie chimique par le biais de processus photocatalytiques implique invariablement un transfert d'énergie photo-induit et un transfert d'électrons. Dans ce contexte, l'objectif de la thèse est d'étudier les processus photo-induits dans les photosystèmes moléculaires utilisant la photolyse par flash laser. Le premier thème de cette thèse porte sur l’étude du transfert monoélectronique dans des systèmes de dyades donneur-accepteur en vue d’optimiser l’efficacité de la séparation des charges et de son application dans la cellule solaire organique photovoltaïque. Le deuxième thème de cette thèse porte sur l’étude de deux systèmes modèles de photosynthèse artificielle étudiés pour la possibilité d’une accumulation de charge par étapes. Ensuite, différents systèmes photocatalytiques, développés pour la photoréduction du CO₂, ont été étudiés. La compréhension des processus photo-induits devraient permettre l’amélioration de l'efficacité de la réduction du CO₂ dans les systèmes photocatalytiques pratiques. / The energy demand of humanity is increasing rapidly, and shows no signs of slowing. Alongside this issue, abuse using fossil fuels is one of the main reasons which leads to an increase in atmospheric CO₂ concentration. These problems have to be solved in terms of both limiting CO₂ emission and finding renewable energy sources to replace fossil fuels. Nowadays, solar energy appears as one of the most effective renewable energy sources. Conversion of solar light energy to electricity in photovoltaics or to chemical energy through photocatalytic processes invariably involves photoinduced energy transfer and electron transfer. In this context, the aim of the thesis focuses on studying photoinduced processes in molecular photosystems using laser flash photolysis. The first theme of this thesis focus on studying single electron transfer in Donor-Acceptor Dyad systems towards optimization efficiency of charge separation and application in the photovoltaic organic solar cell. In the second theme of this thesis, two model systems of artificial photosynthesis were investigated to assess the possibility of stepwise charge accumulation on model molecules. A fairly good global yield of approximately 9% for the two charge accumulation on MV²⁺ molecule was achieved. Then, different photocatalytic systems, which have developed for CO₂ reduction, were studied. Understanding of the photoinduced processes is an important step toward improving the efficiency of reduction of CO₂ in practical photocatalytic systems.
|
736 |
Carotenoid translocation and protein evolution in cyanobacterial photoprotection / Translocation des caroténoïdes et évolution des protéines dans la photoprotection des cyanobactériesMuzzopappa, Fernando 02 December 2019 (has links)
Les cyanobactéries sont des organismes photosynthétiques capables de convertir le CO₂ en composés organiques et de produire de l’oxygène en utilisant l’énergie lumineuse. Néanmoins, de fortes intensités lumineuses saturent l'appareil photosynthétique, ce qui conduit à la production d'espèces réactives de l'oxygène, dangereuses pour la cellule. Pour y faire face, la photoactive orange carotenoid protein (OCP) induit une dissipation thermique de l’énergie excédentaire récoltée par le complexe d’antennes, le phycobilisome (PBS), afin de diminuer l’énergie arrivant aux centres photochimiques. L'OCP est composé de deux domaines), le domaine C-terminal (CTD) et le domaine N-terminal (NTD), reliés par un domaine de liason flexible (linker). Pendant la photoactivation, le caroténoïde est transféré vers le NTD, les domaines se séparent et le NTD peut interagir avec le PBS. Trois familles d'OCP coexistent (OCPX, OCP1 et OCP2) dans les cyanobactéries modernes. Outre l'OCP, de nombreuses cyanobactéries contiennent également des homologues des domaines OCP, le CTDH et HCP. Les HCP sont une famille de protéines caroténoïdes présentant différents traits photoprotecteurs. La plupart d'entre eux sont de très bons quenchers d'oxygène singulet, et un subclade est capable d'interagir avec le PBS et d'induire une dissipation de l'énergie thermique comme l'OCP. Le rôle de CTDH était inconnu. La présence de ces homologues parallèlement à l'OCP a conforté l'idée générale que l'OCP a une origine évolutive modulaire et que la CTDH et HCP pourraient interagir pour former un complexe OCP-like ayant des caractéristiques et une fonction similaires à celles de l'OCP. Dans cette thèse, je présente la première caractérisation des protéines CTDH. Les CTDH sont des dimères se liant à une molécule de caroténoïde. Le rôle principal de la CTDH est de transférer son caroténoïde au HCP. De plus, les CTDH sont capables de récupérer les caroténoïdes des membranes contrairement aux HCP. Ces résultats suggèrent fortement que les CTDH sont des transporteurs de caroténoïde qui assurent le chargement en caroténoïde sur les HCP. Ce nouveau mécanisme de translocation des caroténoïdes pourrait être multidirectionnel. La résolution de deux structures tridimensionnelles de l'ApoCTDH d'Anabaena a montré que la queue C-terminale du CTDH (CTT) peut adopter différentes conformations. De plus, l'analyse de mutation a démontré que le CTT joue un rôle essentiel dans la translocation des caroténoïdes. Enfin, je rapporte une caractérisation moléculaire du linker reliant les domaines de différents OCP modernes et son rôle au cours de l'évolution de l'OCP. Tout d’abord, j’ai caractérisé les OCP des trois subclades, y compris l’OCPX non caractérisé. OCPX et OCP2 présentent une désactivation rapide par rapport à OCP1. Alors que OCP1 et OCPX peuvent dimériser, OCP2 est stable en tant que monomère. Enfin, j'ai constaté que le linker est essentiel pour la désactivation de l'OCP et qu'il régule la photoactivation. Dans OCP1 et OCPX, le linker ralentit la photoactivation, tandis que dans OCP2, il augmente le taux de photoactivation. L'analyse bioinformatique complète cette caractérisation et fournit une image claire de l'évolution de l'OCP pour répondre efficacement aux conditions de stress. / Cyanobacteria are photosynthetic organisms capable of CO₂ conversion into organic compounds and production of O2 by using light energy. Nevertheless, high light intensities saturate the photosynthetic apparatus leading to production of reactive oxygen species, which are dangerous for the cell. To cope with this, the photoactive Orange Carotenoid Protein (OCP) induces thermal dissipation of the excess energy harvested by the antenna complex, the phycobilisome (PBS) to decrease the energy arriving at the photochemical centers. The OCP is composed of two domains connected by a flexible linker, the C-terminal domain (CTD) and the N-terminal domain (NTD). During photoactivation, the carotenoid is translocated to the NTD, the domains separate and the NTD is able to interact with the PBS. Three OCP families co-exist (OCPX, OCP1 and OCP2) in modern cyanobacteria. In addition to the OCP, many cyanobacteria also contain homologs of OCP domains, the CTDH and HCP. The HCPs are a family of carotenoid proteins with different photoprotective traits. Most of them are very good singlet oxygen quenchers, and one sub-clade is able to interact with the PBS and to induce thermal energy dissipation like OCP. The role of CTDH was unknown. The presence of these homologs in parallel to the OCP supported the general idea that the OCP has a modular evolutionary origin and that the CTDH and HCP can interact forming an OCP-like complex with similar characteristics and function than the OCP.In this thesis, I present the first characterization of the CTDH proteins. CTDHs are dimers binding a carotenoid molecule. The main role of the CTDH is to transfer its carotenoid to the HCP. In addition, CTDHs are able to uptake carotenoids from membranes but not HCPs. These results strongly suggested that the CTDHs are carotenoid carriers that ensure the proper carotenoid loading into HCPs. This novel carotenoid translocation mechanism could be multidirectional. The resolution of two tridimensional structures of the ApoCTDH from Anabaena showed that the C-terminal tail of the CTDH (CTT) can populate different conformations. Moreover, mutational analysis demonstrated that the CTT has an essential role in carotenoid translocation. Finally, I report a molecular characterization of the flexible linker connecting the domains of different modern OCPs and its role during the evolution of the OCP. First, I characterized OCPs from the three subclades, including the uncharacterized OCPX. OCPX and OCP2 present a fast deactivation compared with OCP1. While OCP1 and OCPX can dimerize, OCP2 is stable as monomer. Finally, I found that the linker is essential for the OCP deactivation and it regulates the photoactivation. In OCP1 and OCPX the linker slows down the photoactivation, while in OCP2 it increases the photoactivation rate. Bioinformatic analysis complements this characterization and provides a clear picture of the evolution of the OCP to respond efficiently to stress conditions.
|
737 |
The role of iron nutrition in regulating patterns of photosynthesis and nitrogen metabolism in the green alga Scenedesmus quadricaudaAdes, Dennis Raymond 01 January 1987 (has links)
The influence of iron nutrition on patterns of photosynthetic behavior, nitrogen metabolism, and fixed-carbon allocation is reported for a common freshwater green alga. Cultures of Scenedesmus quadricauda were grown in Fraquil medium in which iron concentrations ranged from 1.0 μM to 0.01 μM (log 10-6 to 10-8 M, respectively). Carbon 14 and nitrogen uptake experiments were conducted at photosynthetically saturating and subsaturating photon flux densities.
|
738 |
Molecular and Physiological Responses of Soybean (Glycine max) to Cold and the Stress Hormone EthyleneRobison, Jennifer Dawn 05 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Abiotic stresses, such as cold, are serious agricultural problems resulting in substantial crop and revenue losses. Soybean (Glycine max) is an important worldwide crop for food, feed, fuel, and other products. Soybean has long been considered to be cold-intolerant and incapable of cold acclimation. In contrast to these reports, this study demonstrates that cold acclimation improved freezing tolerance in the domestic soybean cultivar ‘Williams 82’ with 50% enhancement of freezing tolerance after 5.2 +\- 0.6 days of cold exposure. Decreases in light dependent photosynthetic function and efficiency accompanied cold treatment. These decreases were due to an increase in photon dissipation likely driven by a decrease in plastoquinone (PQ) pool size limiting electron flow from photosystem II (PSII) to photosystem I (PSI). Cold-induced damage to operational photosynthesis began at 25 minutes of cold exposure and maximal photosynthesis was disrupted after 6 to 7 hours of cold exposure. Cold exposure caused severe photodamage leading to the loss of PSII reaction centers and photosynthetic efficiency.
Comparisons of eight cultivars of G. max demonstrated a weak correlation between cold acclimation and northern cultivars versus southern cultivars. In the non-domesticated soybean species Glycine soja, the germination rate after cold imbibition was positively correlated with seedling cold acclimation potential. However, the overall cold acclimation potential in G. soja was equal to that of domestic soybean G. max reducing the enthusiasm for the “wild” soybean as an additional source of genetic diversity for cold tolerance.
Despite being relatively cold intolerant, the soybean genome possesses homologs of the major cold responsive CBF/DREB1 transcription factors. These genes are cold-induced in soybean in a similar pattern to that of the cold tolerant model plant species Arabidopsis thaliana. In Arabidopsis, EIN3, a major component of the ethylene signaling pathway, is a negative transcriptional regulator of CBF/DREB1. In contrast to AtEIN3 transcript levels which do not change during cold treatment in Arabidopsis, we observed a cold-dependent 3.6 fold increase in GmEIN3 transcript levels in soybean. We hypothesized that this increase could prevent effective CBF/DREB1 cold regulation in soybean. Analysis of our newly developed cold responsive reporter (AtRD29Aprom::GFP/GUS) soybean transgenic lines demonstrated that inhibition of the ethylene pathway via foliar sprays (AVG, 1-MCP, and silver nitrate) resulted in significant cold-induced GUS activity. Transcripts of GmEIN3A;1 increased in response to ethylene pathway stimulation (ACC and ethephon) and decreased in response to ethylene pathway inhibition in the cold. Additionally, in the cold, inhibition of the ethylene pathway resulted in a significant increase in transcripts of GmDREB1A;1 and GmDREB1A;2 and stimulation of the ethylene pathway led to a decrease in GmDREB1A;1 and GmDREB1B;1 transcripts. To assess the physiological effects of these transcriptional changes; electrolyte leakage, lipid oxidation, free proline content, and photosynthesis were examined. Improvement in electrolyte leakage, a measure of freezing tolerance, was seen only under silver nitrate treatment. Only 1-MCP treatment resulted in significantly decreased lipid oxidation. Transcripts for CBF/DREB1 downstream targets (containing the consensus CRT/DRE motifs) significantly decreased in plants treated with ethylene pathway stimulators in the cold; however, ethylene pathway inhibition generally produced no increase over basal cold levels.
To identify if GmEIN3A;1 was capable of binding to GmDREB1 promoters, the negative regulator GmEIN3A;1 and the positive regulator GmICE1A were cloned and expressed in Escherichia coli (E. coli). Preliminary binding results indicated that GmEIN3A;1 can bind to a double stranded section of the GmDREB1A;1 promoter containing putative EIN3 and ICE1 binding sites. GmICE1A is capable of binding to the same section of the GmDREB1A;1 promoter, though only when single stranded. Additional experiments will be required to demonstrate that GmEIN3A;1 and GmICE1A are capable of binding to the GmDREB1A;1 promoter and this work provides the tools to answer these questions.
Overall, this work provides evidence that the ethylene pathway transcriptionally inhibits the CBF/DREB1 pathway in soybean through the action of GmEIN3A;1. Yet when GmCBF/DREB1 transcripts are upregulated by ethylene pathway inhibition, no consistent change in downstream targets was observed. These data indicate that the limitation in cold tolerance in soybean is due to a yet unidentified target downstream of CBF/DREB1 transcription.
|
739 |
Synthesis and Studies of Wide-Band Capturing BODIPY-Fullerene Based Donor-Acceptor SystemsShao, Shuai 05 1900 (has links)
Artificial photosynthesis is the process, which mimics the natural photosynthesis process in order to convert solar energy to chemical energy. This process can be separated into four parts, which are antenna system, reaction center, water oxidation center, and proton reduction center. If we only focus on the ‘antenna system and reaction center' modules, expanding the absorption band in antenna system and generating long-lived charge separated state in reaction center are two fantastic strategies to design the molecules in order to improve the efficiency of the artificial photosynthesis process.
In the first work of this dissertation, mono-18-crown-6 and mono-ammonium binding strategy was used to connect BODIPY- C60 supramolecular based donor–acceptor conjugates. The meso- position of BODIPY was modified by benzo-18-crown-6, and the 3, 5 methyl positions were replaced by two styryl groups, which covered additional donor (triphenylamine or 10-methylphenothiazine). The acceptor is a fulleropyrrolidine derivative, which included an ethyl ammonium cation. The absorbance wavelengths of the donor covered 300-850 nm, which is the visible/near IR region (wide band capturing). The ultrafast charge separation and relatively slow charge recombination was found from femtosecond transient absorption study.
Next, a ‘two point' bis-18-crown-6 and bis-ammonium binding strategy was utilized to link BODIPY- C60 supramolecular based donor–acceptor conjugates. In this case, the meso- position of the BODIPY was modified by a secondary donor (triphenylamine, phenothiazine, or ferrocene). And the 3, 5 methyl positions were replaced by two styryl groups, which included benzo-18-crown-6. The acceptor (fulleropyrrolidine) was functionalized by bis-alky ammonium cations. The absorbance/ fluorescence emission titration and computational studies supported that the ‘two-point' strategy has stronger binding than ‘one-point' strategy. The relatively slow charge separation was found in these donor-acceptor conjugates.
To extend the second work, a pristine BODIPY was linked to the meso- position of the BODIPY-bis-benzo-18-crown-6. When the acceptor (C60-bis- ammonium) was added to the system, a sequential energy transfer (EnT) followed by electron transfer (ET) process was performed. The energy transfer was found from absorbance/ fluorescence emission studies, and the photoinduced electron transfer was observed from femtosecond and nanosecond transient absorption study. This is a great mode to mimic the ‘antenna-reaction center' events of natural photosynthesis.
In the last work of this dissertation, triplet sensitizers (I2BODIPY and I2azaBODIPY) covalently linked with a C60 to form the donor-acceptor system. In this work, triplet charge separated state (long-lived charge separated state) was expected. According to the femtosecond transient absorption studies, we observed the singlet charge separation was faster than the intersystem crossing process, that was the reason that only singlet charge separated state was found for I2BODIPY-C60, and no electron transfer was found for I2 azaBODIPY-C60.
|
740 |
Involvement of the modulation of proton motive force in the regulation of photosynthesis / 光合成制御におけるプロトン駆動力調節の関与Wang, Caijuan 23 March 2016 (has links)
Chapter 1: “Role of cyclic electron transport around photosystem I in the regulation of proton motive force” is based on the following paper. Caijuan Wang, Hiroshi Yamamoto, Toshiharu Shikanai, Role of cyclic electron transport around photosystem I in regulating proton motive force, Biochimica et Biophysica Acta (BBA) - Bioenergetics, Volume 1847, Issue 9, September 2015, Pages 931-938, ISSN 0005-2728, http://dx.doi.org/10.1016/j.bbabio.2014.11.013.(http://www.sciencedirect.com/science/article/pii/S0005272814006586) / 京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19535号 / 理博第4195号 / 新制||理||1602(附属図書館) / 32571 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 鹿内 利治, 教授 西村 いくこ, 教授 長谷 あきら / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
|
Page generated in 0.0188 seconds