We investigate experimentally and numerically the quantitative dependence of characteristics of a low-velocity intensity source（LVIS） of atomic beam on light parameters, especially the polarization of cooling laser ...We investigate experimentally and numerically the quantitative dependence of characteristics of a low-velocity intensity source（LVIS） of atomic beam on light parameters, especially the polarization of cooling laser along the atomic beam axis（pushing beam）. By changing the polarization of the pushing beam, the longitudinal mean velocity of a rubidium atomic beam can be tuned continuously from 10 to 20 m/s and the flux can range from 3 × 10^-8 to 1 × 10^-9 atoms/s, corresponding to the maximum sensitivity of the velocity with respect to the polarization angle of 20（m/s）/rad and the mean sensitivity of flux of 1.2 × 10^-9（atoms/s）/rad. The mechanism is explained with a Monte-Carlo based numerical simulation method, which shows a qualitative agreement with the experimental result. This is also a demonstration of a method enabling the fast and continuous modulation of a low-velocity intense source of cold atomic beam on the velocity or flux,which can be used in many fields, like the development of a cold atomic beam interferometer and atom lithography.展开更多
Herein,we demonstrate an optical thermometer based on single Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_4)_7 phosphors,which were prepared by traditional solid-state reaction technique under a reduction atmosphere.Considerations ...Herein,we demonstrate an optical thermometer based on single Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_4)_7 phosphors,which were prepared by traditional solid-state reaction technique under a reduction atmosphere.Considerations on the bond length obtained by the crystal structure refinement and the dependent photoluminescence performances allow to assign the two distinct emission bands to Eu^(2+)ions occupied Cal-Ca3 and Mg2 sites.Moreover,the blue and red emitting bands perfectly match with the photosynthetic action spectrum,which can enhance the indoor plant photosynthesis.The optimal doping content of Eu^(2+)ions in this Ca_(9)Mg_(1.5)(PO_(4))_(7)system is 3 mol%.The corresponding concentration quenching effect is verified as dipole-dipole interaction with the critical distance of 3.315 nm.Furthermore,by exploiting the fluorescence intensity technique,the optical thermal resistance properties of Ca_(9)Mg_(1.5)(PO_4)_7:Eu^(2+)are identified based on the temperature dependent emission spectra in a range of 303-523 K.In detail,the maximum absolute and relative sensitivity S_(a)and S_(r)of Ca_9Mg_(1.5)(PO_(4))_(7):Eu^(2+)thermometer are as high as 0.637%/K and 0.3155 K^(-1),respectively.Consequently,the Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_(4))_(7)phosphors establish a bifunctional platfo rm for both optical the rmometer and plant growth lighting via multi-site occupancies.展开更多
To examine the synergetic effects of ocean acidification(OA)and light intensity on the photosynthetic performance of marine diatoms,the marine centric diatom Thalassiosira weissflogii was cultured under ambient low CO...To examine the synergetic effects of ocean acidification(OA)and light intensity on the photosynthetic performance of marine diatoms,the marine centric diatom Thalassiosira weissflogii was cultured under ambient low CO_(2)(LC,390μatm)and elevated high CO_(2)(HC,1000μatm)levels under low-light(LL,60μmol m^(-2)s^(-1))or high-light(HL,220μmol m^(-2)s^(-1))conditions for over 20 generations.HL stimulated the growth rate by 128 and 99%but decreased cell size by 9 and 7%under LC and HC conditions,respectively.However,HC did not change the growth rate under LL but decreased it by 9%under HL.LL combined with HC decreased both maximum quantum yield(FV/FM)and effective quantum yield(ΦPSII),measured under either low or high actinic light.When exposed to UV radiation(UVR),LL-grown cells were more prone to UVA exposure,with higher UVA and UVR inducing inhibition ofΦPSII compared with HL-grown cells.Light use efficiency(α)and maximum relative electron transport rate(rETRmax)were inhibited more in the HC-grown cells when UVR(UVA and UVB)was present,particularly under LL.Our results indicate that the growth light history influences the cell growth and photosynthetic responses to OA and UVR.展开更多
The adaptations and responses of photosynthesis to long- and short-term growth light gradient treatments were investigated in five subtropical forest plants, namely Pinus massoniana Lamb., Schima superba Gardn. et Cha...The adaptations and responses of photosynthesis to long- and short-term growth light gradient treatments were investigated in five subtropical forest plants, namely Pinus massoniana Lamb., Schima superba Gardn. et Champ., Castanopsis flssa （Champ. ex Benth.） Rehd. et Wils., Acmena acuminatissima （BI.） Merr et Perry, and Cryptocarya concinna Hance. With diurnal changes in sunlight and air temperature, the de-epoxidation state and lutein content in the five woody plants under three light Intensities first increased and then decreased during the day. However, maximal photochemical efficiency （FvFm; where Fm is the maximum fluorescence yield and Fv Is variable fluorescence） and the photochemical quantum yields of photosystem （PS）Ⅱ （φPSⅡ） of the species examined changed in the opposite manner, with those in plants grown under 100% natural light changing the most. After long-term treatment （21 months）, anti-oxidant capacity （1,1-diphenyl-2-picrylhydrazyl radical （DPPH.）-scavenging capacity） and utilization of excitation energy showed differences in modulation by different light intensities. It was shown that A. acuminatissima and C. concinna, as dominant species in the late succession stage of a subtropical forest in Dinghu mountain, South China, were better able to adapt to different light environments. However, P. massonlana, the pioneer species of this forest, exhibited less adaptation to low light intensity and was definitely eliminated by the forest succession process.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61473166 and 41404146)
文摘We investigate experimentally and numerically the quantitative dependence of characteristics of a low-velocity intensity source（LVIS） of atomic beam on light parameters, especially the polarization of cooling laser along the atomic beam axis（pushing beam）. By changing the polarization of the pushing beam, the longitudinal mean velocity of a rubidium atomic beam can be tuned continuously from 10 to 20 m/s and the flux can range from 3 × 10^-8 to 1 × 10^-9 atoms/s, corresponding to the maximum sensitivity of the velocity with respect to the polarization angle of 20（m/s）/rad and the mean sensitivity of flux of 1.2 × 10^-9（atoms/s）/rad. The mechanism is explained with a Monte-Carlo based numerical simulation method, which shows a qualitative agreement with the experimental result. This is also a demonstration of a method enabling the fast and continuous modulation of a low-velocity intense source of cold atomic beam on the velocity or flux,which can be used in many fields, like the development of a cold atomic beam interferometer and atom lithography.
基金the National Natural Science Foundation of China(52104272)the Fundamental Research Founds for the Central Universities(2652020020)the Program National Key R&D Program of China(2021YFC1910602-01)。
文摘Herein,we demonstrate an optical thermometer based on single Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_4)_7 phosphors,which were prepared by traditional solid-state reaction technique under a reduction atmosphere.Considerations on the bond length obtained by the crystal structure refinement and the dependent photoluminescence performances allow to assign the two distinct emission bands to Eu^(2+)ions occupied Cal-Ca3 and Mg2 sites.Moreover,the blue and red emitting bands perfectly match with the photosynthetic action spectrum,which can enhance the indoor plant photosynthesis.The optimal doping content of Eu^(2+)ions in this Ca_(9)Mg_(1.5)(PO_(4))_(7)system is 3 mol%.The corresponding concentration quenching effect is verified as dipole-dipole interaction with the critical distance of 3.315 nm.Furthermore,by exploiting the fluorescence intensity technique,the optical thermal resistance properties of Ca_(9)Mg_(1.5)(PO_4)_7:Eu^(2+)are identified based on the temperature dependent emission spectra in a range of 303-523 K.In detail,the maximum absolute and relative sensitivity S_(a)and S_(r)of Ca_9Mg_(1.5)(PO_(4))_(7):Eu^(2+)thermometer are as high as 0.637%/K and 0.3155 K^(-1),respectively.Consequently,the Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_(4))_(7)phosphors establish a bifunctional platfo rm for both optical the rmometer and plant growth lighting via multi-site occupancies.
基金This study was supported by the National Natural Science Foundation of China(41720104005,41721005,41890803)Key Research and Development Program of Anhui Province(202004i07020004)+3 种基金Excellent Youth Scholars Support Program of Anhui Province(gxyq2021212)MEL Visiting Fellowship Program(MELRS2008)Research Platform of Eco-Environmental Protection Research Centre of Xin’an River Basin,Huangshan University(kypt202102)The authors are grateful to the laboratory engineers Xianglan Zeng and Wenyan Zhao for their logistical and technical support.
文摘To examine the synergetic effects of ocean acidification(OA)and light intensity on the photosynthetic performance of marine diatoms,the marine centric diatom Thalassiosira weissflogii was cultured under ambient low CO_(2)(LC,390μatm)and elevated high CO_(2)(HC,1000μatm)levels under low-light(LL,60μmol m^(-2)s^(-1))or high-light(HL,220μmol m^(-2)s^(-1))conditions for over 20 generations.HL stimulated the growth rate by 128 and 99%but decreased cell size by 9 and 7%under LC and HC conditions,respectively.However,HC did not change the growth rate under LL but decreased it by 9%under HL.LL combined with HC decreased both maximum quantum yield(FV/FM)and effective quantum yield(ΦPSII),measured under either low or high actinic light.When exposed to UV radiation(UVR),LL-grown cells were more prone to UVA exposure,with higher UVA and UVR inducing inhibition ofΦPSII compared with HL-grown cells.Light use efficiency(α)and maximum relative electron transport rate(rETRmax)were inhibited more in the HC-grown cells when UVR(UVA and UVB)was present,particularly under LL.Our results indicate that the growth light history influences the cell growth and photosynthetic responses to OA and UVR.
基金Supported by the National Natural Science Foundation of China （30470282）.Acknowledgements The authors thank Jian Liu （South China Botanical Garden, the Chinese Academy of Sciences） for his technical assistance with the HPLC procedure.
文摘The adaptations and responses of photosynthesis to long- and short-term growth light gradient treatments were investigated in five subtropical forest plants, namely Pinus massoniana Lamb., Schima superba Gardn. et Champ., Castanopsis flssa （Champ. ex Benth.） Rehd. et Wils., Acmena acuminatissima （BI.） Merr et Perry, and Cryptocarya concinna Hance. With diurnal changes in sunlight and air temperature, the de-epoxidation state and lutein content in the five woody plants under three light Intensities first increased and then decreased during the day. However, maximal photochemical efficiency （FvFm; where Fm is the maximum fluorescence yield and Fv Is variable fluorescence） and the photochemical quantum yields of photosystem （PS）Ⅱ （φPSⅡ） of the species examined changed in the opposite manner, with those in plants grown under 100% natural light changing the most. After long-term treatment （21 months）, anti-oxidant capacity （1,1-diphenyl-2-picrylhydrazyl radical （DPPH.）-scavenging capacity） and utilization of excitation energy showed differences in modulation by different light intensities. It was shown that A. acuminatissima and C. concinna, as dominant species in the late succession stage of a subtropical forest in Dinghu mountain, South China, were better able to adapt to different light environments. However, P. massonlana, the pioneer species of this forest, exhibited less adaptation to low light intensity and was definitely eliminated by the forest succession process.
