Electron spin resonance （ESR） in polycrystalline diamond films grown by dc arc-jet and microwave plasma chemical vapour deposition is studied. The films with nitrogen impurity concentration up to 8 × 10^18 cm^-...Electron spin resonance （ESR） in polycrystalline diamond films grown by dc arc-jet and microwave plasma chemical vapour deposition is studied. The films with nitrogen impurity concentration up to 8 × 10^18 cm^-3 are also characterized by Raman, cathodoluminescence and optical absorption spectra. The ESR signal from P1 centre with g-factor of 2.0024 （nitrogen impurity atom occupying C site in diamond lattice） is found to exhibit an inversion with increasing the microwave power in an H102 resonator. The spin inversion effect could be of interest for further consideration of N-doped diamonds as a medium for masers operated at room temperature.展开更多
Mn 2+ EPR intensity recorded in the Chinese loess_paleosol sequence shows close correlation with magnetic susceptibility and Sr content as well as the oscillation of paleoclimate. Thus Mn 2+ EPR signal can serve as an...Mn 2+ EPR intensity recorded in the Chinese loess_paleosol sequence shows close correlation with magnetic susceptibility and Sr content as well as the oscillation of paleoclimate. Thus Mn 2+ EPR signal can serve as an indicator sensitive to the East Asia summer monsoon intensity fluctuations.展开更多
PHOTOSYSTEM Ⅱ （PS Ⅱ） particles capable of O<sub>2</sub> evolution contain reaction center polypeptides D1 and D2, cytchrome b559, chlorophyll （Chl）-binding proteins CP47 and CP43, three extrinsic pol...PHOTOSYSTEM Ⅱ （PS Ⅱ） particles capable of O<sub>2</sub> evolution contain reaction center polypeptides D1 and D2, cytchrome b559, chlorophyll （Chl）-binding proteins CP47 and CP43, three extrinsic polypeptides （with apparent molecular masses of 17, 23 and 33 ku） and cofactors needed for light energy conversion. After illumination, PS Ⅱ oxygen evolution complex （OEC） catalyzes the oxidization of water to molecular oxygen through S<sub>0</sub>→S<sub>4</sub> redox state transition. The three extrinsic polypeptides have been revealed to be closely related to the photosynthetic O<sub>2</sub> evolution.展开更多
A PSII reaction center complex consisting of three polypeptides, D_1, D_2 and Cyt. b_(559), was first purified from broad bean leaves. The complex was fairly active inDCIP photoreduction in the presence of DPC, and sh...A PSII reaction center complex consisting of three polypeptides, D_1, D_2 and Cyt. b_(559), was first purified from broad bean leaves. The complex was fairly active inDCIP photoreduction in the presence of DPC, and showed signal Ⅱs either in the dark or under illumination. The complex also contained manganese atoms. Its Mn^(2+)-EPR intensity decreased by about 40% under continuous illumination and recovered to the original level when the complex was transferred to the dark. The above results indicated that the complex reported here contains all of the PSII electron transport chain components from the secondary donor Z to the stable primary electron acceptor Q_A, and it is possible that the complex contains manganese binding sites. The alternation in dark and illumination can induce reversible valence changes of the manganese atoms in the purified complex.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 50372007 and 50572007, Russian Fund for Basic Research under Grant Nos 06-02-39031 and 07-03-00956, and Belarus Republic Foundation for Basic Research under Grant No F05-281.
文摘Electron spin resonance （ESR） in polycrystalline diamond films grown by dc arc-jet and microwave plasma chemical vapour deposition is studied. The films with nitrogen impurity concentration up to 8 × 10^18 cm^-3 are also characterized by Raman, cathodoluminescence and optical absorption spectra. The ESR signal from P1 centre with g-factor of 2.0024 （nitrogen impurity atom occupying C site in diamond lattice） is found to exhibit an inversion with increasing the microwave power in an H102 resonator. The spin inversion effect could be of interest for further consideration of N-doped diamonds as a medium for masers operated at room temperature.
文摘Mn 2+ EPR intensity recorded in the Chinese loess_paleosol sequence shows close correlation with magnetic susceptibility and Sr content as well as the oscillation of paleoclimate. Thus Mn 2+ EPR signal can serve as an indicator sensitive to the East Asia summer monsoon intensity fluctuations.
文摘PHOTOSYSTEM Ⅱ （PS Ⅱ） particles capable of O<sub>2</sub> evolution contain reaction center polypeptides D1 and D2, cytchrome b559, chlorophyll （Chl）-binding proteins CP47 and CP43, three extrinsic polypeptides （with apparent molecular masses of 17, 23 and 33 ku） and cofactors needed for light energy conversion. After illumination, PS Ⅱ oxygen evolution complex （OEC） catalyzes the oxidization of water to molecular oxygen through S<sub>0</sub>→S<sub>4</sub> redox state transition. The three extrinsic polypeptides have been revealed to be closely related to the photosynthetic O<sub>2</sub> evolution.
基金Project supported by the National Natural Science Foundation of China
文摘A PSII reaction center complex consisting of three polypeptides, D_1, D_2 and Cyt. b_(559), was first purified from broad bean leaves. The complex was fairly active inDCIP photoreduction in the presence of DPC, and showed signal Ⅱs either in the dark or under illumination. The complex also contained manganese atoms. Its Mn^(2+)-EPR intensity decreased by about 40% under continuous illumination and recovered to the original level when the complex was transferred to the dark. The above results indicated that the complex reported here contains all of the PSII electron transport chain components from the secondary donor Z to the stable primary electron acceptor Q_A, and it is possible that the complex contains manganese binding sites. The alternation in dark and illumination can induce reversible valence changes of the manganese atoms in the purified complex.
