It is well known that in pyroxene structure, there are two metal sites, M1 and M2.Generally speaking, ferrous iron in each of these sites would normally be expected to give rise to a doublet. However, anomies have bee...It is well known that in pyroxene structure, there are two metal sites, M1 and M2.Generally speaking, ferrous iron in each of these sites would normally be expected to give rise to a doublet. However, anomies have been found in the relative areas of the peaks in the room temperature spectra of some clinopyroxene (CPX) when the above assigninent is folowed. Ac-cording to the calculation of Next Nearest Neighbor configurations of divalent cations in M1,we found that the four configurations of M1 can be divided into two groups. One group is 3Ca configuration that increases with the content of Ca (p. f. u); the other group is made up of three No-3Ca configurations that decrease with the content of Ca. The two groups contribute to the spectrum structure of M1, so in this study we fit two doublets for ferrous iron in M1.Though there were severa reports on Fe3+ in tetrahedral site previously, it wa not sure that Fe3+ occupies the T site is a universal fact in CPX, despite of the content of A1. We found that the Fe3+ in the T site fitted by Medauer spectroscopy is negatively correlated to the Si content in the T site and positively correlated to the Fe3 + in the T site estimated on the suppo-sition that Fe3+ and Al occupy the T site randomly. If it is true, it is important in the model-ing of ion exchange geobarometries and gepthermornetries.展开更多
The electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,t...The electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,the intrinsic complexity of this multi-step reaction severely constrains both the selectivity and efficiency of NO3RR.Copper-based electrocatalysts have been extensively investigated for NO_(3)RR but often suffer from nitrite(NO_(2)^(−))accumulation,which stems from insufficient NO_(3)^(−)adsorption strength.This limitation often leads to rapid catalyst deactivation,hindered hydrogenation pathways,and reduced overall efficiency.Herein,we report a one-step green chemical reduction method to synthesize PtCuSnCo quarternary alloy nanoparticles with homogeneously distributed elements.Under practical NO3−concentrations,the optimized catalyst exhibited an impressive Faradaic efficiency approaching 100%and an outstanding selectivity of 95.6±2.9%.Mechanistic insights uncovered that SnCo sites robustly facilitated NO_(3)^(−)adsorption,complemented by the proficiency of PtCu sites in NO3−reduction.The synergistic spatial neighborhood effect between SnCo and PtCu sites efficiently stabilizes NO_(3)^(−)deoxygenation and suppresses NO_(2)^(−)accumulation.This tandem architecture achieves a finely tuned balance between adsorption strength and deoxygenation kinetics,enabling highly selective and efficient NO3RR.Our findings emphasize the indispensable role of engineered multi-metallic catalysts in overcoming persistent challenges of NO3RR,paving the way for advanced NH3 synthesis and environmental remediation.展开更多
Background: Light is an important environmental factor affecting the growth and survival of plants in forest communities. The competition for light resources and divergent responses to light may affect plant species c...Background: Light is an important environmental factor affecting the growth and survival of plants in forest communities. The competition for light resources and divergent responses to light may affect plant species coexistence in natural forests through niche partitioning and environmental filtering, respectively.Methods: In the present study, sequences of light-response-related functional genes were extracted from transcriptomic data of 99 tree species in a subtropical forest and average and nearest taxon phylogenetic diversity of adult(A_Apd’, A_NTpd’) and seedling neighbors(S_Apd’, S_NTpd’) around each focal seedling were calculated to evaluate effects of differentiation in light-response-related genes on community assembly processes.Results: The results showed that seedling survival was related to S_NTpd’, S_Apd’and A_Apd’of two chlorophyll ab-binding proteins involved in the assembly of photosystem Ⅱ and two genes responsive to light intensity,indicating seedlings surrounded by neighbors with distinct light responses tended to have high survival rates.Conclusions: Our results indicated that niche partitioning due to competition for light resources between plants may act as the key mechanism in determining seedling dynamics in subtropical forests.展开更多
基于Neyman-Rubin潜在结果框架,构建k近邻核估计量来测度响应变量随机缺失情形下的条件平均处理效应(conditional average treatment effect,CATE),旨在评估不同处理方式对个体的影响.证明了k近邻核估计量的几乎完全收敛性和渐近正态性...基于Neyman-Rubin潜在结果框架,构建k近邻核估计量来测度响应变量随机缺失情形下的条件平均处理效应(conditional average treatment effect,CATE),旨在评估不同处理方式对个体的影响.证明了k近邻核估计量的几乎完全收敛性和渐近正态性.数值模拟表明k近邻核估计量的表现优良,利用真实数据进行实证分析,实证结果显示k近邻核估计量具有较小的平均绝对偏差和均方根误差.展开更多
With the hypothesis of simple units integration to create new reactivities,a strategy for the synthesis of polyfunctionalized 5-alkenyl-3-carbonylfurans fromγ-hydroxyl enal and 1,3-dicarbonyl compounds is established...With the hypothesis of simple units integration to create new reactivities,a strategy for the synthesis of polyfunctionalized 5-alkenyl-3-carbonylfurans fromγ-hydroxyl enal and 1,3-dicarbonyl compounds is established,featuring readily available starting materials,high efficiency,good functional groups compatibility,green chemistry with high atom economy and only water release,etc.,to provide a series of polyfunctionalized 5-alkenyl-3-carbonylfurans,which could be applied to the late-stage functionalization of naturally occurring compounds and bioactive molecules,as well as the transformation to pyrroles and polycyclic aromatic hydrocarbon via electrocyclic reaction.Theγ-hydroxyl has played an important role in the unexpected process of ring opening isomerization of 2H-pyran to furanones,as confirmed by detailed mechanistic studies.展开更多
文摘It is well known that in pyroxene structure, there are two metal sites, M1 and M2.Generally speaking, ferrous iron in each of these sites would normally be expected to give rise to a doublet. However, anomies have been found in the relative areas of the peaks in the room temperature spectra of some clinopyroxene (CPX) when the above assigninent is folowed. Ac-cording to the calculation of Next Nearest Neighbor configurations of divalent cations in M1,we found that the four configurations of M1 can be divided into two groups. One group is 3Ca configuration that increases with the content of Ca (p. f. u); the other group is made up of three No-3Ca configurations that decrease with the content of Ca. The two groups contribute to the spectrum structure of M1, so in this study we fit two doublets for ferrous iron in M1.Though there were severa reports on Fe3+ in tetrahedral site previously, it wa not sure that Fe3+ occupies the T site is a universal fact in CPX, despite of the content of A1. We found that the Fe3+ in the T site fitted by Medauer spectroscopy is negatively correlated to the Si content in the T site and positively correlated to the Fe3 + in the T site estimated on the suppo-sition that Fe3+ and Al occupy the T site randomly. If it is true, it is important in the model-ing of ion exchange geobarometries and gepthermornetries.
文摘The electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,the intrinsic complexity of this multi-step reaction severely constrains both the selectivity and efficiency of NO3RR.Copper-based electrocatalysts have been extensively investigated for NO_(3)RR but often suffer from nitrite(NO_(2)^(−))accumulation,which stems from insufficient NO_(3)^(−)adsorption strength.This limitation often leads to rapid catalyst deactivation,hindered hydrogenation pathways,and reduced overall efficiency.Herein,we report a one-step green chemical reduction method to synthesize PtCuSnCo quarternary alloy nanoparticles with homogeneously distributed elements.Under practical NO3−concentrations,the optimized catalyst exhibited an impressive Faradaic efficiency approaching 100%and an outstanding selectivity of 95.6±2.9%.Mechanistic insights uncovered that SnCo sites robustly facilitated NO_(3)^(−)adsorption,complemented by the proficiency of PtCu sites in NO3−reduction.The synergistic spatial neighborhood effect between SnCo and PtCu sites efficiently stabilizes NO_(3)^(−)deoxygenation and suppresses NO_(2)^(−)accumulation.This tandem architecture achieves a finely tuned balance between adsorption strength and deoxygenation kinetics,enabling highly selective and efficient NO3RR.Our findings emphasize the indispensable role of engineered multi-metallic catalysts in overcoming persistent challenges of NO3RR,paving the way for advanced NH3 synthesis and environmental remediation.
基金funded by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB31000000)National Natural Science Foundation of China(No.32161123003)+1 种基金Beijing Natural Science Foundation(No.5202018)National Key Research Development Program of China(No.2022YFF0802300)。
文摘Background: Light is an important environmental factor affecting the growth and survival of plants in forest communities. The competition for light resources and divergent responses to light may affect plant species coexistence in natural forests through niche partitioning and environmental filtering, respectively.Methods: In the present study, sequences of light-response-related functional genes were extracted from transcriptomic data of 99 tree species in a subtropical forest and average and nearest taxon phylogenetic diversity of adult(A_Apd’, A_NTpd’) and seedling neighbors(S_Apd’, S_NTpd’) around each focal seedling were calculated to evaluate effects of differentiation in light-response-related genes on community assembly processes.Results: The results showed that seedling survival was related to S_NTpd’, S_Apd’and A_Apd’of two chlorophyll ab-binding proteins involved in the assembly of photosystem Ⅱ and two genes responsive to light intensity,indicating seedlings surrounded by neighbors with distinct light responses tended to have high survival rates.Conclusions: Our results indicated that niche partitioning due to competition for light resources between plants may act as the key mechanism in determining seedling dynamics in subtropical forests.
文摘基于Neyman-Rubin潜在结果框架,构建k近邻核估计量来测度响应变量随机缺失情形下的条件平均处理效应(conditional average treatment effect,CATE),旨在评估不同处理方式对个体的影响.证明了k近邻核估计量的几乎完全收敛性和渐近正态性.数值模拟表明k近邻核估计量的表现优良,利用真实数据进行实证分析,实证结果显示k近邻核估计量具有较小的平均绝对偏差和均方根误差.
基金Financial support from National Natural Science Foundation of China(Grant No.22201187)the starting grant from Capital Medical University(Grant No.3100-12400123)。
文摘With the hypothesis of simple units integration to create new reactivities,a strategy for the synthesis of polyfunctionalized 5-alkenyl-3-carbonylfurans fromγ-hydroxyl enal and 1,3-dicarbonyl compounds is established,featuring readily available starting materials,high efficiency,good functional groups compatibility,green chemistry with high atom economy and only water release,etc.,to provide a series of polyfunctionalized 5-alkenyl-3-carbonylfurans,which could be applied to the late-stage functionalization of naturally occurring compounds and bioactive molecules,as well as the transformation to pyrroles and polycyclic aromatic hydrocarbon via electrocyclic reaction.Theγ-hydroxyl has played an important role in the unexpected process of ring opening isomerization of 2H-pyran to furanones,as confirmed by detailed mechanistic studies.
