Linear dichroism (LD) spectroscopy is an important technique in the study of the orientation and organization of pigments in the photosynthetic membrane complexes in vivo and in vitro . In this work, the orient...Linear dichroism (LD) spectroscopy is an important technique in the study of the orientation and organization of pigments in the photosynthetic membrane complexes in vivo and in vitro . In this work, the orientation of the pigments in the isolated photosystem Ⅱ (PSⅡ) sub_core reaction center complexes was analyzed and characterized by means of low temperature absorption and LD spectroscopy. The preparations containing different amounts of CP47 isolated from spinach (Spinacia oleracea L.) chloroplast were used in order to investigate the orientation of pigments in the PSⅡ sub_core CP47/D1/D2/Cyt b_559 (CP47/D1/D2) complexes. Chlorophyll a (Chl a) absorbing at 680 nm in CP47/D1/D2/Cyt b_559 complex showed an orientation of the Q y transition parallel to the membrane plane. It is proposed that there are two forms of β_carotene (β_Car) in CP47/D1/D2/Cyt b_559 complex, denoted as β_Car (Ⅰ) and β_Car (Ⅱ), with different orientations, β_Car (Ⅰ) at 470 and 505 nm is roughly parallel to the membrane plane, and β_Car (Ⅱ) at 460 and 490 nm seems to be perpendicular orientation. Upon the photoinhibitory experiment β_Car (Ⅱ) was found to be photosensitive and easily photodamaged. It also showed that the positive LD signal observed at 680 nm was quite complicated. This signal is tentatively attributed to P680 and some Chl a of antenna in CP47 protein based upon our measurements.展开更多
This paper describes a campaign of WEC （wave energy converter） testing and presents a selection of the results related to the measured motions and mooring tensions. A 1：20 physical model has been successfully deplo...This paper describes a campaign of WEC （wave energy converter） testing and presents a selection of the results related to the measured motions and mooring tensions. A 1：20 physical model has been successfully deployed using a three point mooring installed at sea （Strangford Lough, NI） in 10 m depth. In calm weather the overall dynamics of mooring tensions is dominated by the tidal cycle due to the progressive lifting of the heavy chain with the increase in water depth on the flood and gradual lowering on the ebb. In flesh winds the dynamics is very complex, but can be studied with the aid of mathematical modelling. A simulation model was used to assess the dynamics of the mooring lines, and the results of open water tests have been compared with the model＇s performance. The results indicate that, in general, the model shows a reasonable agreement with the observations. The WEC＇s motions and the measured loads on the leading mooring line appear to relate to the concurrent environmental conditions. The data obtained can therefore be used for the model＇s calibration and further improvements, which is valuable for improving the WEC＇s design and operational characteristics. This may be important not only in relation to the issues of reliability and power take off, but also in terms of minimising the adverse effects of mooring lines on bottom sediments, as well as indirect effects of the eroded particles on a wide range of aquatic processes.展开更多
Previous studies on haze formation focused mainly on the various chemical components in aerosol particles and their physicochemical effects on particle behaviour(e.g.,generation,growth,and agglomeration).This paper de...Previous studies on haze formation focused mainly on the various chemical components in aerosol particles and their physicochemical effects on particle behaviour(e.g.,generation,growth,and agglomeration).This paper describes the measurement of the charging state on atmospheric aerosol particles,which could be affected by meteorological conditions.A series of experiments on particle charging state and meteorological factors was undertaken on the roof of the west 4th building on the Qujiang Campus at Xi'an Jiaotong University(China).Measurements were conducted approximately 20 m above ground level,Our results showed that most atmospheric particles carried net negative or positive charge and that the electric charge on the particles varied diurnally and seasonally.The average amount of charge on particles was higher in winter than in summer.The number concentration of charged particles was higher during the day than overnight.Obvious difference in the average charge of aerosol particles was found between sand-dust days and haze days.A strong relationship was found between the PM2.s concentration,charge amount on particles,and humidity.Our findings show that particle formation and growth could partly be attributed to variation in particle charging state,which is related to meteorological conditions including atmospheric humidity.展开更多
基金Commissaire Energie de Atomique de Francethe 9th Five-Year Major Program of the National Natural Science Foundation of China(39890390)+1 种基金the State Key Basic Research Development Plan of China(973)(G1998010100)Innovation of Laboratory of Photosynthests Basic Research,Institute of Botany,The Chinese Acadeny of Sciences
文摘Linear dichroism (LD) spectroscopy is an important technique in the study of the orientation and organization of pigments in the photosynthetic membrane complexes in vivo and in vitro . In this work, the orientation of the pigments in the isolated photosystem Ⅱ (PSⅡ) sub_core reaction center complexes was analyzed and characterized by means of low temperature absorption and LD spectroscopy. The preparations containing different amounts of CP47 isolated from spinach (Spinacia oleracea L.) chloroplast were used in order to investigate the orientation of pigments in the PSⅡ sub_core CP47/D1/D2/Cyt b_559 (CP47/D1/D2) complexes. Chlorophyll a (Chl a) absorbing at 680 nm in CP47/D1/D2/Cyt b_559 complex showed an orientation of the Q y transition parallel to the membrane plane. It is proposed that there are two forms of β_carotene (β_Car) in CP47/D1/D2/Cyt b_559 complex, denoted as β_Car (Ⅰ) and β_Car (Ⅱ), with different orientations, β_Car (Ⅰ) at 470 and 505 nm is roughly parallel to the membrane plane, and β_Car (Ⅱ) at 460 and 490 nm seems to be perpendicular orientation. Upon the photoinhibitory experiment β_Car (Ⅱ) was found to be photosensitive and easily photodamaged. It also showed that the positive LD signal observed at 680 nm was quite complicated. This signal is tentatively attributed to P680 and some Chl a of antenna in CP47 protein based upon our measurements.
文摘This paper describes a campaign of WEC （wave energy converter） testing and presents a selection of the results related to the measured motions and mooring tensions. A 1：20 physical model has been successfully deployed using a three point mooring installed at sea （Strangford Lough, NI） in 10 m depth. In calm weather the overall dynamics of mooring tensions is dominated by the tidal cycle due to the progressive lifting of the heavy chain with the increase in water depth on the flood and gradual lowering on the ebb. In flesh winds the dynamics is very complex, but can be studied with the aid of mathematical modelling. A simulation model was used to assess the dynamics of the mooring lines, and the results of open water tests have been compared with the model＇s performance. The results indicate that, in general, the model shows a reasonable agreement with the observations. The WEC＇s motions and the measured loads on the leading mooring line appear to relate to the concurrent environmental conditions. The data obtained can therefore be used for the model＇s calibration and further improvements, which is valuable for improving the WEC＇s design and operational characteristics. This may be important not only in relation to the issues of reliability and power take off, but also in terms of minimising the adverse effects of mooring lines on bottom sediments, as well as indirect effects of the eroded particles on a wide range of aquatic processes.
基金supported by the Natural Science Foundation of China(Grant No.11872295)the Strategic Research Grant,City University of Hong Kong(Grant No.Cityli-SRG 7004867)the State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,CAS(Grant No.SKLLQG1807),China。
文摘Previous studies on haze formation focused mainly on the various chemical components in aerosol particles and their physicochemical effects on particle behaviour(e.g.,generation,growth,and agglomeration).This paper describes the measurement of the charging state on atmospheric aerosol particles,which could be affected by meteorological conditions.A series of experiments on particle charging state and meteorological factors was undertaken on the roof of the west 4th building on the Qujiang Campus at Xi'an Jiaotong University(China).Measurements were conducted approximately 20 m above ground level,Our results showed that most atmospheric particles carried net negative or positive charge and that the electric charge on the particles varied diurnally and seasonally.The average amount of charge on particles was higher in winter than in summer.The number concentration of charged particles was higher during the day than overnight.Obvious difference in the average charge of aerosol particles was found between sand-dust days and haze days.A strong relationship was found between the PM2.s concentration,charge amount on particles,and humidity.Our findings show that particle formation and growth could partly be attributed to variation in particle charging state,which is related to meteorological conditions including atmospheric humidity.
