The effects of major veins severing on morphological and physiological features of sweetgum （Liquidambar styraciflua L.） leaves were investigated by observing leaf color change and measuring leaf temperature, green/...The effects of major veins severing on morphological and physiological features of sweetgum （Liquidambar styraciflua L.） leaves were investigated by observing leaf color change and measuring leaf temperature, green/luminance （G/L） value of half-lobes, leaf stomata conductance, and water content in Yamaguchi University, Japan. The palmately veined leaves of sweetgum （Liquidambar styraciflua L.） were found more sensitive to the major vein severing than that of other species Major veins severing resulted in serious water stresses, as indicated by the persistent reddening and/or advanced reddening of local leaf, lower leaf stomatal conductance, and higher leaf temperature, etc. Severed leaf can be clearly divided into non-severed area, transitional area, and stressed area, which the three areas have different colours and temperature. The major vein barrier can also be seen clearly. The persistent reddening and advanced reddening seem consistent with the phenomenon of red crown top of some sweetgum trees and may have similar mechanism.展开更多
Sea surface height (SSH) variability in the Mindanao Dome (MD) region is found to be one of the strong variations in the northern Pacific. It is only weaker than that in the Kuroshio Extension area, and is comparable ...Sea surface height (SSH) variability in the Mindanao Dome (MD) region is found to be one of the strong variations in the northern Pacific. It is only weaker than that in the Kuroshio Extension area, and is comparable to that in the North Pacific Subtropical Countercurrent region. Based on a 1.5-layer reduced gravity model, we analyzed SSH variations in this region and their responses to northern tropical Pacific winds. The average SSH anomaly in the region varies mainly on a seasonal scale, with significant periods of 0.5 and 1 year, ENSO time scale2-7years, and time scale in excess of 8 years. Annual and long-term variabilities are comparably stronger. These variations are essentially a response to the northern tropical Pacific winds. On seasonal and ENSO time scales, they are mainly caused by wind anomalies east of the region, which generate westward-propagating, long Rossby waves. On time scales longer than 8 years, they are mostly induced by local Ekman pumping. Long-term SSH variations in the MD region and their responses to local winds are examined and discussed for the first time .展开更多
As a result of the left-lateral strike-slipping of the Altyn Tagh fault in Neotectonic period, a contra-rotational structure, namely the Zhaobishan vortex structure, has developed at the juncture of the main Altyn Tag...As a result of the left-lateral strike-slipping of the Altyn Tagh fault in Neotectonic period, a contra-rotational structure, namely the Zhaobishan vortex structure, has developed at the juncture of the main Altyn Tagh fault and the northern fringe fault of the Qilian Mountains. Preliminary analysis on the deformation and evolution of the Zhaobishan vortex structure. In combination with the previous data, suggests that the tectonic transform between the Altyn Tagh fault and the northern fringe fault of the Qilian Mountains attributes to the deformation of the rotational structure. The existence of a series of rotational structures along the Altyn Tagh fault and on the northeastern edge of the Qinghai-Xizang(Tibet) plateau indicate that as the substance in the northern Qinghai-Xizang (Tibet) plateau moves clockwise around the eastern tectonic knot of the Himalayas, rotational structures become the principal mode on the northern marginal zone of the Plateau of transforming and absorbing tectonic deformation.展开更多
The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. Fr...The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. From variations of temperature at 87 and 94 km obtained from OH （6-2） and 02 （0-1） airglow spectra, temperature at night is shown lowest in the summer and highest in the winter. In summer, average temperature at 87 km is 173.9 K, lower than average temperature 180.1 K at 94 km. But in winter, average temperature at 87 Ion is 201.2 K, higher than average temperature 194.8 K at 94 kin. The altitude of mesopause in Beijing is below 87 km in summer and above 94 km in winter. There are about 120-150 days when the mesopause locates below 87 km, which is in agreement with the results of SABER/TIMED. Variations of temperatures at 87 and 94 km are analyzed by harmonic method. Our results show that amplitudes of annual oscillation of temperature at 87 and 94 km are 17.5 and 7.8 K respectively. Amplitudes of semi-annual oscillation at 87 and 94 km are 1.6 and 5.3 K, which are smaller than those of annual oscillation. Although there are differences among different observations because of different locations and different instruments, our results are in general agreement with observation at similar latitude as Beijing.展开更多
A mesoscale weather research and forecasting(WRF)model was used to simulate a cold vortex that developed over Northeast China during June 19–23,2010.The simulation used high vertical resolution to reproduce the key f...A mesoscale weather research and forecasting(WRF)model was used to simulate a cold vortex that developed over Northeast China during June 19–23,2010.The simulation used high vertical resolution to reproduce the key features of the cold vortex development.Characteristics of the associated stratosphere-troposphere exchange(STE),specifically the spatiotemporal distribution of the cross-tropopause mass flux(CTF),were investigated using the Wei formula.The simulation results showed that the net mass exchange induced by the cold vortex was controlled by stratosphere-to-troposphere transport(STT)processes.In the pre-formation stage of the cold vortex(i.e.,the development of the trough and ridge),active exchange was evident.Over the lifecycle of the cold vortex,STT processes prevailed at the rear of the trough and moving vortex,whereas troposphere-to-stratosphere transport(TST)processes prevailed at the front end.This spatial pattern was caused by temporal fluctuations of the tropopause.However,because of the cancellation of the upward flux by the downward flux,the contribution of the tropopause fluctuation term to the net mass exchange was only minor.In this case,horizontal motion dominated the net mass exchange.The time evolution of the CTF exhibited three characteristics:(1)the predominance of the STT during the pre-formation stage;(2)the formation and development of the cold vortex,in which the CTF varied in a fluctuating pattern from TST to STT to TST;and(3)the prevalence of the STT during the decay stage.展开更多
Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled ...Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled with gas chromatography and flame photometric detector after in situ ethylation with sodium tetraethylborate. Butyltin species were detected in sixteen vinegar samples and ranged from 0.012 to 14.10 lag Sn L 1. The detection rate of white vinegar is higher than that of rice vinegar and mature vinegar. Vinegar samples with relatively high butyltin concentration (〉1.5 μg Sn L-1) were those stored in plastic bags, indicating that the plastic bag was one of the possible sources of butyltin contamination. This was further confirmed by the leaching experiments of three selected plastic bags, and monobutyltin was detected in the leaching solvents. According to the estimation, the average daily intake of total butyltin compounds through vinegar consumption is about 0.04 ng Sn/kg b.w., much lower than the Tolerable Daily Intake (TDI) of 100 ng Sn/kg b.w. set by the European Food Safety Authority (EFSA).展开更多
文摘The effects of major veins severing on morphological and physiological features of sweetgum （Liquidambar styraciflua L.） leaves were investigated by observing leaf color change and measuring leaf temperature, green/luminance （G/L） value of half-lobes, leaf stomata conductance, and water content in Yamaguchi University, Japan. The palmately veined leaves of sweetgum （Liquidambar styraciflua L.） were found more sensitive to the major vein severing than that of other species Major veins severing resulted in serious water stresses, as indicated by the persistent reddening and/or advanced reddening of local leaf, lower leaf stomatal conductance, and higher leaf temperature, etc. Severed leaf can be clearly divided into non-severed area, transitional area, and stressed area, which the three areas have different colours and temperature. The major vein barrier can also be seen clearly. The persistent reddening and advanced reddening seem consistent with the phenomenon of red crown top of some sweetgum trees and may have similar mechanism.
基金Supported by the National Natural Science Foundation of China (No.40890151)the National Basic Research Program of China (973 Program)(No.2012CB417401)
文摘Sea surface height (SSH) variability in the Mindanao Dome (MD) region is found to be one of the strong variations in the northern Pacific. It is only weaker than that in the Kuroshio Extension area, and is comparable to that in the North Pacific Subtropical Countercurrent region. Based on a 1.5-layer reduced gravity model, we analyzed SSH variations in this region and their responses to northern tropical Pacific winds. The average SSH anomaly in the region varies mainly on a seasonal scale, with significant periods of 0.5 and 1 year, ENSO time scale2-7years, and time scale in excess of 8 years. Annual and long-term variabilities are comparably stronger. These variations are essentially a response to the northern tropical Pacific winds. On seasonal and ENSO time scales, they are mainly caused by wind anomalies east of the region, which generate westward-propagating, long Rossby waves. On time scales longer than 8 years, they are mostly induced by local Ekman pumping. Long-term SSH variations in the MD region and their responses to local winds are examined and discussed for the first time .
文摘As a result of the left-lateral strike-slipping of the Altyn Tagh fault in Neotectonic period, a contra-rotational structure, namely the Zhaobishan vortex structure, has developed at the juncture of the main Altyn Tagh fault and the northern fringe fault of the Qilian Mountains. Preliminary analysis on the deformation and evolution of the Zhaobishan vortex structure. In combination with the previous data, suggests that the tectonic transform between the Altyn Tagh fault and the northern fringe fault of the Qilian Mountains attributes to the deformation of the rotational structure. The existence of a series of rotational structures along the Altyn Tagh fault and on the northeastern edge of the Qinghai-Xizang(Tibet) plateau indicate that as the substance in the northern Qinghai-Xizang (Tibet) plateau moves clockwise around the eastern tectonic knot of the Himalayas, rotational structures become the principal mode on the northern marginal zone of the Plateau of transforming and absorbing tectonic deformation.
基金supported by the National Natural Science Foundation of China (Grant No. 40974086)the National Important Basic Research Project (Grant No. 2011CB811405)
文摘The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 2009 are used to study night mesopause temperature in Beijing. From variations of temperature at 87 and 94 km obtained from OH （6-2） and 02 （0-1） airglow spectra, temperature at night is shown lowest in the summer and highest in the winter. In summer, average temperature at 87 km is 173.9 K, lower than average temperature 180.1 K at 94 km. But in winter, average temperature at 87 Ion is 201.2 K, higher than average temperature 194.8 K at 94 kin. The altitude of mesopause in Beijing is below 87 km in summer and above 94 km in winter. There are about 120-150 days when the mesopause locates below 87 km, which is in agreement with the results of SABER/TIMED. Variations of temperatures at 87 and 94 km are analyzed by harmonic method. Our results show that amplitudes of annual oscillation of temperature at 87 and 94 km are 17.5 and 7.8 K respectively. Amplitudes of semi-annual oscillation at 87 and 94 km are 1.6 and 5.3 K, which are smaller than those of annual oscillation. Although there are differences among different observations because of different locations and different instruments, our results are in general agreement with observation at similar latitude as Beijing.
基金the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 41305038)
文摘A mesoscale weather research and forecasting(WRF)model was used to simulate a cold vortex that developed over Northeast China during June 19–23,2010.The simulation used high vertical resolution to reproduce the key features of the cold vortex development.Characteristics of the associated stratosphere-troposphere exchange(STE),specifically the spatiotemporal distribution of the cross-tropopause mass flux(CTF),were investigated using the Wei formula.The simulation results showed that the net mass exchange induced by the cold vortex was controlled by stratosphere-to-troposphere transport(STT)processes.In the pre-formation stage of the cold vortex(i.e.,the development of the trough and ridge),active exchange was evident.Over the lifecycle of the cold vortex,STT processes prevailed at the rear of the trough and moving vortex,whereas troposphere-to-stratosphere transport(TST)processes prevailed at the front end.This spatial pattern was caused by temporal fluctuations of the tropopause.However,because of the cancellation of the upward flux by the downward flux,the contribution of the tropopause fluctuation term to the net mass exchange was only minor.In this case,horizontal motion dominated the net mass exchange.The time evolution of the CTF exhibited three characteristics:(1)the predominance of the STT during the pre-formation stage;(2)the formation and development of the cold vortex,in which the CTF varied in a fluctuating pattern from TST to STT to TST;and(3)the prevalence of the STT during the decay stage.
基金support under the National Basic Research Program of China (2009CB421605)National Key Water Program(2009ZX07207-002-03)National Natural Science Foundation of China (20977096)
文摘Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled with gas chromatography and flame photometric detector after in situ ethylation with sodium tetraethylborate. Butyltin species were detected in sixteen vinegar samples and ranged from 0.012 to 14.10 lag Sn L 1. The detection rate of white vinegar is higher than that of rice vinegar and mature vinegar. Vinegar samples with relatively high butyltin concentration (〉1.5 μg Sn L-1) were those stored in plastic bags, indicating that the plastic bag was one of the possible sources of butyltin contamination. This was further confirmed by the leaching experiments of three selected plastic bags, and monobutyltin was detected in the leaching solvents. According to the estimation, the average daily intake of total butyltin compounds through vinegar consumption is about 0.04 ng Sn/kg b.w., much lower than the Tolerable Daily Intake (TDI) of 100 ng Sn/kg b.w. set by the European Food Safety Authority (EFSA).
