In this paper, the light trapping characteristics of glass substrate with hemisphere pit （HP） arrays in thin film Si solar cells are theoretically studied via a numerical approach. It is found that the HP glass subs...In this paper, the light trapping characteristics of glass substrate with hemisphere pit （HP） arrays in thin film Si solar cells are theoretically studied via a numerical approach. It is found that the HP glass substrate has good antireflection properties. Its surface reflectance can be reduced by - 50% compared with planar glass. The HP arrays can make the unabsorbed light return to the absorbing layer of solar cells, and the ratio of second absorption approximately equals 30%. Thus, the glass substrate with the hemisphere pit arrays （HP glass） can effectively reduce the total reflectivity of a solar celt from 20% to 13%. The lip glass can also prolong the optical path length. The numerical results show that the total optical path length of the thin film Si solar cell covered with the HP glass increases from 2ω to 409. These results are basically consistent with the experimental results.展开更多
Background: Cyanobacteria phycocyanins (Cps) have already shown powerful antioxidant properties. In human cells submitted to oxidative stress the telomeres length decrease, the expression of progerin and the activity ...Background: Cyanobacteria phycocyanins (Cps) have already shown powerful antioxidant properties. In human cells submitted to oxidative stress the telomeres length decrease, the expression of progerin and the activity of mTOR are increased. At our knowledge, there is no published data on Cps correlated with ultraviolet radiation (UV) and blue light effects in human cells regarding telomeres’ length, progerin expression or mTOR1 complex activity. Objectives: In this study, we sought to assess 1) telomeres’ length in newborn human fibroblasts exposed to UV and blue light;2) progerin production in mature human normal fibroblasts exposed to UV;3) mTOR1 activation in adult human normal keratinocytes exposed to UV, analyzing the activity of a Cyanobacteria phycocyanin (Cp) in these in vitro models. Materials and Methods: Human skin fibroblasts or human normal keratinocytes were cultured—in the absence or in the presence of Cp and submitted to UVB + UVA and blue light irradiations. Telomeres’ length, progerin expression and mTOR1 activity were then assessed by molecular biology and immuno-enzymatic methods. Results: In cultured fibroblasts exposed to irradiations and treated by Cp, telomeres’ shortage and progerin expression were lower compared to irradiated untreated cells. In cultured keratinocytes treated by Cp and exposed to irradiations, the mTOR activity was lower compared to irradiated untreated cells. Conclusions: In these in vitro studies on human skin fibroblasts and on normal human keratinocytes, the cyanobacteria phycocyanin (Cp) showed a decrease of damages induced by UV and blue light expressed by telomeres preservation and downregulation of progerin expression and of mTOR activity, thus showing skin anti-aging and photo-protective potential.展开更多
The efficiency of a silicon solar cell is directly linked to the quantity of carrier photogenerated in its base. It increases with the increase of the quantity of carrier in the base of the solar cell. The carrier den...The efficiency of a silicon solar cell is directly linked to the quantity of carrier photogenerated in its base. It increases with the increase of the quantity of carrier in the base of the solar cell. The carrier density in the base of the solar cell increases with the increase of the flux of photons that crosses the solar cell. One of the methods used to increase the flux of photon on the illuminated side of the solar cell is the intensification of the illumination light. However, the intensification of the light come with the increase of the energy released by thermalization, the collision between carriers, their braking due to the carriers concentration gradient electric field which lead to increase the temperature in the base of the solar cell. This work presents a 3-D study, of the effect of the temperature on the electronic parameters of a polycrystalline silicon solar under intense light illumination. The electronic parameters on which we analyze the temperature effect are:?the mobility of solar cell carriers?(electrons and holes),?their diffusion coefficient, their diffusion length and their distribution in the bulk of the base. To study the effect of the temperature on electronic parameters, we take into account, the dependence of carriers (electrons and holes) mobility with the temperature (μn,(T)?μp(T)). Then, the resolution of the continuity equation,which is a function of the carriers gradient electric field and the carriers mobility,?leads to the expressions of?the diffusion coefficient, the diffusion length, and the density of carriers which are function of the temperature. Then, we studied the effects of the temperature on the diffusion parameters in order to explain their effect on the behavior the carriers distribution in intermediate, short circuit and open circuit operating modes at several positions in the base depth. It appears through this study that the diffusion coefficient and the diffusion length decrease with the increase of the temperature. We observe also that with the increase of the temperature, the density of carriers in the base of the solar cell in short circuit and open voltage operating modes increases. In intermediate operating mode, the density of carriers increases also with the temperature but it is function of the base depth.展开更多
目的:系统评价低能量红光对于近视儿童脉络膜厚度(ChT)和等效球镜度(SE)及眼轴长度(AL)的影响。方法:通过检索Pubmed、Embase、Cochrane Library、Web of Science、中国知网、万方、维普网及中国生物医学文献数据库共8个数据库,从建库至...目的:系统评价低能量红光对于近视儿童脉络膜厚度(ChT)和等效球镜度(SE)及眼轴长度(AL)的影响。方法:通过检索Pubmed、Embase、Cochrane Library、Web of Science、中国知网、万方、维普网及中国生物医学文献数据库共8个数据库,从建库至2023-01期间所有关于低能量红光干预近视发展的随机对照试验,红光干预作为试验组,仅配戴单焦眼镜作为对照组。按照Cochrane手册要求进行文献质量及偏倚风险评价。Meta分析由Revman5.4软件完成。结果:共计纳入8篇有关低能量红光干预近视发展的随机对照试验研究。用于分析ChT变化的样本量为红光组407眼,对照组425眼;用于分析SE变化差值的样本量为红光组490眼,对照组518眼;纳入AL分析的样本量为红光组518眼,对照组539眼。红光组与对照组ChT、SE、AL比较均有差异(ChT:WMD=37.81,95%CI:21.55~54.07,P<0.001;SE:WMD=0.58,95%CI:0.46~0.71,P<0.001;AL:WMD=-0.31,95%CI:-0.39~-0.24,P<0.001)。结论:特定的红光有助于促进ChT而抑制SE及AL增加,但其远期效果及副作用尚不清楚,上述结论还需要更多大样本的随机对照研究进一步明确。展开更多
The current definition of the meter as based on the time of light transmission and the postulated universal constant light speed is ill-defined and inadequate. The definition fails to identify which second is required...The current definition of the meter as based on the time of light transmission and the postulated universal constant light speed is ill-defined and inadequate. The definition fails to identify which second is required, whether to use coordinate or proper time, or which method to construct an exact meter, besides ignoring gravity’s effect. In Einstein’s 1905 paper that defined special relativity, Einstein stipulated correctly that light traversing the ends of a resting rod takes equal time transmissions in either direction. If that rod is oriented parallel to a constant velocity, a photon from one end of the moving rod takes a longer time span with a universal constant light speed to overtake the receding end and takes a shorter time span to intercept the approaching end of the rod when transmitted in the opposite direction, resulting in a longer roundtrip distance of photons traversing the moving rod versus the resting rod. Length contraction undercompensates this difference. Einstein did not address this issue. However, Einstein claimed the unequal time intervals over the moving rod versus equal intervals over the resting rod are because simultaneous states for the resting observer and resting rod are nonsimultaneous for the constant moving observer. This contradicts his first postulate of relativity: any state of a physical system (e.g., equal timed traverses of photons moving over a rod) is unaffected by a constant translational velocity between inertial reference frames. An in-depth analysis examines Einstein’s thought experiment for an adequate redefinition. The analysis reveals one-way photon velocities obey vector velocity addition involving moving photon sources, but it proves by induction that roundtrip photon traverses have an average speed that is identical to the standard light speed c. Thus, Einstein’s second postulate of relativity is not general, but is valid for roundtrip traverses of photon transmissions. This may change many physical concepts, since one-way velocities for photons and particles are not limited by the second postulate. A suggested redefinition of the meter is submitted.展开更多
基金Project supported by the National High-Tech Research and Development Program of China(Grant No.2011AA050518)
文摘In this paper, the light trapping characteristics of glass substrate with hemisphere pit （HP） arrays in thin film Si solar cells are theoretically studied via a numerical approach. It is found that the HP glass substrate has good antireflection properties. Its surface reflectance can be reduced by - 50% compared with planar glass. The HP arrays can make the unabsorbed light return to the absorbing layer of solar cells, and the ratio of second absorption approximately equals 30%. Thus, the glass substrate with the hemisphere pit arrays （HP glass） can effectively reduce the total reflectivity of a solar celt from 20% to 13%. The lip glass can also prolong the optical path length. The numerical results show that the total optical path length of the thin film Si solar cell covered with the HP glass increases from 2ω to 409. These results are basically consistent with the experimental results.
文摘Background: Cyanobacteria phycocyanins (Cps) have already shown powerful antioxidant properties. In human cells submitted to oxidative stress the telomeres length decrease, the expression of progerin and the activity of mTOR are increased. At our knowledge, there is no published data on Cps correlated with ultraviolet radiation (UV) and blue light effects in human cells regarding telomeres’ length, progerin expression or mTOR1 complex activity. Objectives: In this study, we sought to assess 1) telomeres’ length in newborn human fibroblasts exposed to UV and blue light;2) progerin production in mature human normal fibroblasts exposed to UV;3) mTOR1 activation in adult human normal keratinocytes exposed to UV, analyzing the activity of a Cyanobacteria phycocyanin (Cp) in these in vitro models. Materials and Methods: Human skin fibroblasts or human normal keratinocytes were cultured—in the absence or in the presence of Cp and submitted to UVB + UVA and blue light irradiations. Telomeres’ length, progerin expression and mTOR1 activity were then assessed by molecular biology and immuno-enzymatic methods. Results: In cultured fibroblasts exposed to irradiations and treated by Cp, telomeres’ shortage and progerin expression were lower compared to irradiated untreated cells. In cultured keratinocytes treated by Cp and exposed to irradiations, the mTOR activity was lower compared to irradiated untreated cells. Conclusions: In these in vitro studies on human skin fibroblasts and on normal human keratinocytes, the cyanobacteria phycocyanin (Cp) showed a decrease of damages induced by UV and blue light expressed by telomeres preservation and downregulation of progerin expression and of mTOR activity, thus showing skin anti-aging and photo-protective potential.
文摘The efficiency of a silicon solar cell is directly linked to the quantity of carrier photogenerated in its base. It increases with the increase of the quantity of carrier in the base of the solar cell. The carrier density in the base of the solar cell increases with the increase of the flux of photons that crosses the solar cell. One of the methods used to increase the flux of photon on the illuminated side of the solar cell is the intensification of the illumination light. However, the intensification of the light come with the increase of the energy released by thermalization, the collision between carriers, their braking due to the carriers concentration gradient electric field which lead to increase the temperature in the base of the solar cell. This work presents a 3-D study, of the effect of the temperature on the electronic parameters of a polycrystalline silicon solar under intense light illumination. The electronic parameters on which we analyze the temperature effect are:?the mobility of solar cell carriers?(electrons and holes),?their diffusion coefficient, their diffusion length and their distribution in the bulk of the base. To study the effect of the temperature on electronic parameters, we take into account, the dependence of carriers (electrons and holes) mobility with the temperature (μn,(T)?μp(T)). Then, the resolution of the continuity equation,which is a function of the carriers gradient electric field and the carriers mobility,?leads to the expressions of?the diffusion coefficient, the diffusion length, and the density of carriers which are function of the temperature. Then, we studied the effects of the temperature on the diffusion parameters in order to explain their effect on the behavior the carriers distribution in intermediate, short circuit and open circuit operating modes at several positions in the base depth. It appears through this study that the diffusion coefficient and the diffusion length decrease with the increase of the temperature. We observe also that with the increase of the temperature, the density of carriers in the base of the solar cell in short circuit and open voltage operating modes increases. In intermediate operating mode, the density of carriers increases also with the temperature but it is function of the base depth.
文摘目的:系统评价低能量红光对于近视儿童脉络膜厚度(ChT)和等效球镜度(SE)及眼轴长度(AL)的影响。方法:通过检索Pubmed、Embase、Cochrane Library、Web of Science、中国知网、万方、维普网及中国生物医学文献数据库共8个数据库,从建库至2023-01期间所有关于低能量红光干预近视发展的随机对照试验,红光干预作为试验组,仅配戴单焦眼镜作为对照组。按照Cochrane手册要求进行文献质量及偏倚风险评价。Meta分析由Revman5.4软件完成。结果:共计纳入8篇有关低能量红光干预近视发展的随机对照试验研究。用于分析ChT变化的样本量为红光组407眼,对照组425眼;用于分析SE变化差值的样本量为红光组490眼,对照组518眼;纳入AL分析的样本量为红光组518眼,对照组539眼。红光组与对照组ChT、SE、AL比较均有差异(ChT:WMD=37.81,95%CI:21.55~54.07,P<0.001;SE:WMD=0.58,95%CI:0.46~0.71,P<0.001;AL:WMD=-0.31,95%CI:-0.39~-0.24,P<0.001)。结论:特定的红光有助于促进ChT而抑制SE及AL增加,但其远期效果及副作用尚不清楚,上述结论还需要更多大样本的随机对照研究进一步明确。
文摘The current definition of the meter as based on the time of light transmission and the postulated universal constant light speed is ill-defined and inadequate. The definition fails to identify which second is required, whether to use coordinate or proper time, or which method to construct an exact meter, besides ignoring gravity’s effect. In Einstein’s 1905 paper that defined special relativity, Einstein stipulated correctly that light traversing the ends of a resting rod takes equal time transmissions in either direction. If that rod is oriented parallel to a constant velocity, a photon from one end of the moving rod takes a longer time span with a universal constant light speed to overtake the receding end and takes a shorter time span to intercept the approaching end of the rod when transmitted in the opposite direction, resulting in a longer roundtrip distance of photons traversing the moving rod versus the resting rod. Length contraction undercompensates this difference. Einstein did not address this issue. However, Einstein claimed the unequal time intervals over the moving rod versus equal intervals over the resting rod are because simultaneous states for the resting observer and resting rod are nonsimultaneous for the constant moving observer. This contradicts his first postulate of relativity: any state of a physical system (e.g., equal timed traverses of photons moving over a rod) is unaffected by a constant translational velocity between inertial reference frames. An in-depth analysis examines Einstein’s thought experiment for an adequate redefinition. The analysis reveals one-way photon velocities obey vector velocity addition involving moving photon sources, but it proves by induction that roundtrip photon traverses have an average speed that is identical to the standard light speed c. Thus, Einstein’s second postulate of relativity is not general, but is valid for roundtrip traverses of photon transmissions. This may change many physical concepts, since one-way velocities for photons and particles are not limited by the second postulate. A suggested redefinition of the meter is submitted.
