Formamidine lead triiodide(FAPbI_(3))perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency(PCE).However,random nucleation,phase transition...Formamidine lead triiodide(FAPbI_(3))perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency(PCE).However,random nucleation,phase transition,and lattice defects are still the key challenges limiting the quality of FAPbI_(3) films.Previous studies show that the introduction or adding of seeds in the precursor is effective to promote the nucleation and crystallization of perovskite films.Nevertheless,the seed-assisted approach focuses on heterogeneous seeds or hetero-composites,which inevitably induce a lattice-mismatch,the genera-tion of strain or defects,and the phase segregation in the perovskite films.Herein,we first demonstrate that high-quality perovskite films are controllably prepared using α-and δ-phases mixed FAPbI_(3) micro-crystal as the homogeneous seeds with the one-step antisolvent method.The partially dissolved seeds with suitable sizes improve the crystallinity of the perovskite flm with preferable orientation,improved carrier lifetime,and increased carrier mobility.More importantly,the α-phase-containing seeds promote the formation of α-phase FAPbI_(3) films,leading to the reduction of residual lattice strain and the suppres-sion of I-ion migration.Besides,the adding of dimethyl 2,6-pyridine dicarboxylate(DPD)into the pre-cursor further suppresses the generation of defects,contributing to the PCE of devices prepared in air ambient being significantly improved to 23.75%,among the highest PCEs for fully air-processed FAPbI_(3) solar cells.The unpackaged target devices possess a high stability,maintaining 80%of the initial PCE under simulated solar illumination exceeding 800 h.展开更多
There are many reservoirs in China,and serious reservoir sedimentation affects reservoir function and reservoir safety.It is of great significance for restoring the reservoir capacity,improving the efficiency of the r...There are many reservoirs in China,and serious reservoir sedimentation affects reservoir function and reservoir safety.It is of great significance for restoring the reservoir capacity,improving the efficiency of the reservoir and prolonging the service life of the reservoir to carry out the research on reservoir sedimentation control and storage capacity recovery technology,in the case of fewer and fewer good dam sites suitable for the construction of the reservoir and the increasing accumulation of reservoir sedimentation.In this paper,influence factor of the storage loss,sedimentation control and reservoir capacity recovery technology in China are briefly reviewed.It is necessary to carry out research work on reservoir sedimentation investigation and reservoir siltation mechanism and control measures.展开更多
Thermoelectrics has played a fascinating role in the developments of direct energy conversion technologies.Over the past decade,sulfur-based thermoelectric materials have been significantly advanced in optimizing elec...Thermoelectrics has played a fascinating role in the developments of direct energy conversion technologies.Over the past decade,sulfur-based thermoelectric materials have been significantly advanced in optimizing electrical and thermal transport due to their similarities in chemical and structural properties with tellurides and selenides.This review provides research progress on metal sulfides,particularly focuses on materials exhibiting high thermoelectric figure of merit(ZT>1.0).It highlights the potential compounds,e.g.Cu-S,Sn-S,Pb-S based,and polysulfides.Great strategies of superionic conducting,band configuration tuning,high-entropy alloying,and anomalous harmonic scattering are try to demonstrate the performance-improved mechanisms for thermoelectric sulfides.In addition,some common synthesis recipes are briefly introduced,and thereby making potential candidates as excellent alternatives for producing thermoelectric power generators in the mid temperature.Key outcomes along with how to further improve the thermoelectric performance and promote its scale-up applications are also outlined at the end.展开更多
Orchidaceae(with>28,000 orchid species)are one of the two largest plant families,with economically and ecologically important species,and occupy global and diverse niches with primary distribution in rainforests.Am...Orchidaceae(with>28,000 orchid species)are one of the two largest plant families,with economically and ecologically important species,and occupy global and diverse niches with primary distribution in rainforests.Among orchids,70%grow on other plants as epiphytes;epiphytes contribute up to~50%of the plant diversity in rainforests and provide food and shelter for diverse animals and microbes,thereby contributing to the health of these ecosystems.Orchids account for over two-thirds of vascular epiphytes and provide an excellent model for studying evolution of epiphytism.Extensive phylogenetic studies of Orchidaceae and subgroups have;been crucial for understanding relationships among many orchid lineages,although some uncertainties remain.For example,in the largest subfamily Epidendroideae with nearly all epiphytic orchids,relationships among some tribes and many subtribes are still controversial,hampering evolutionary analyses of epiphytism.Here we obtained 1,450 low-copy nuclear genes from 610 orchid species,including 431 with newly generated transcriptomes,and used them for the reconstruction of robust Orchidaceae phylogenetic trees with highly supported placements of tribes and subtribes.We also provide generally wellsupported phylogenetic placements of 131 genera and 437 species that were not sampled by previous plastid and nuclear phylogenomic studies.Molecular clock analyses estimated the Orchidaceae origin at~132 million years ago(Ma)and divergences of most subtribes from 52 to 29 Ma.Character reconstruction supports at least 14 parallel origins of epiphytism;one such origin was placed at the most recent common ancestor of~95%of epiphytic orchids and linked to modern rainforests.Ten occurrences of rapid increase in the diversification rate were detected within Epidendroideae near and after the K-Pg boundary,contributing to~80%of the Orchidaceae diversity.This study provides a robust and the largest family-wide Orchidaceae nuclear phylogenetic tree thus far and new insights into the evolution of epiphytism in vascular plants.展开更多
Establishment of a national park protection system in China,including the latest target proposed to protect at least 30%of the land area,calls for a comprehensive exploration of conservation priorities incorporating m...Establishment of a national park protection system in China,including the latest target proposed to protect at least 30%of the land area,calls for a comprehensive exploration of conservation priorities incorporating multiple diversity facets.We herein evaluate the spatial distribution of Chinese flowering plants from the perspectives of richness,uniqueness,vulnerability,and evolutionary history,by integrating three mega-phylogenies and comprehensive distribution data.We detect significantly high consistency among hotspots of different diversity measures for Chinese flowering plants,suggesting that multiple facets of evolutionary diversity are concentrically distributed in China.Affording legal protection to these areas is expected to maximize positive conservation outcomes.We propose two integrative diversity indices by incorporating three richness-based and three phylogeny-based measures,respectively.Both methods identify areas with high species richness,but the integrative phylogeny-based index also locates key areas with ancient and unique evolutionary histories(e.g.,Ailao-Wuliang Mts,Dabie Mts,Hainan rainforest,Karst area of Yunnan-Guizhou-Guangxi,Nanling Mts,and southeast coastal regions).Of all the diversity indices explored,phylogenetic endemism maximizes the incidental protection of other indices in most cases,emphasizing its significance for conservation planning.Finally,42 priority areas are identified by combining the 5%-criterion hotspots of two integrative indices and the minimum area to protect all threatened species analyzed.These priorities cover only 13.3%of China's land area,but host 97.1%of species richness(23,394/24,095),96.5%of endemic species(11,841/12,274),100%of threatened species(2,613/2,613),and 99.3%of phylogenetic diversity for flowering plants involved in this study.These frameworks provide a solid scientific basis for national park planning in China.展开更多
Isobaric specific heat capacity(Cp)is an important parameter not only in physics but also for most materials.Its accurate measurement is particularly critical for performance evaluation of thermoelectric materials,but...Isobaric specific heat capacity(Cp)is an important parameter not only in physics but also for most materials.Its accurate measurement is particularly critical for performance evaluation of thermoelectric materials,but the experiments by differential scanning calorimetry(DSC)often lead to large uncertainties in the measurements,especially at elevated temperatures.In this study,we propose a simple method to determine Cp by measuring the sound velocity(υ)based on lattice vibration and expansion theory.The relative standard error of theυis smaller than 1%,showing good accuracy and repeatability.The calculated Cp at elevated temperature(>300 K)increases slightly with increasing temperature due to the lattice expansion,which is more reasonable than the Dulong–Petit value.展开更多
Fabrication of nanoparticle-dispersed composites is an effective strategy for enhancing the performance of thermoelectric materials,and in particular SiC nanoparticles have been often used to create composites with Bi...Fabrication of nanoparticle-dispersed composites is an effective strategy for enhancing the performance of thermoelectric materials,and in particular SiC nanoparticles have been often used to create composites with Bi_(2)Te_(3)-based applied thermoelectric materials.However,the effect of particle size on the thermoelectric performance is unclear.This work systematically investigated the electrical and thermal properties of a series of(Bi,Sb)_(2)Te_(3)-based nanocomposites containing dispersed SiC nanoparticles of different sizes.It was found that particle size has a significant impact on the electrical properties with smaller SiC nanoparticles giving rise to higher electrical conductivity.Even though the dispersed SiC nanoparticles enhanced the Seebeck coefficient,no apparent dependence of the enhancement on the particle size was observed.It was also found that smaller SiC nanoparticles scatter phonons to some extent while the larger nanoparticles contribute to increased thermal conductivity.Eventually,the highest ZT value of 1.12 was obtained in 30 nm-SiC dispersed sample,corresponding to an increase by 18%from 0.95 for the matrix made from commercial scraps,and then the ZT was further boosted to 1.33 by optimizing the matrix composition and expelling excess Te during the optimized spark plasma sintering process.This work proves that the dispersion of smaller SiC nanoparticles in p-type(Bi,Sb)_(2)Te_(3) materials is more effective than the dispersion of larger nanoparticles.In addition,it is revealed that additional compositional and/or processing optimization is vital and effective for obtaining further performance enhancement for nanocomposites of SiC nanoparticles dispersed in(Bi,Sb)_(2)Te_(3).展开更多
Wüstite-type Fe(0.78)Mn(0.22)O nanocubes,with a uniform size of^10 nm in edge length,have been synthesized by thermal-decomposition approach.The nanocubes exhibited superparamagnetic properties at room temperatur...Wüstite-type Fe(0.78)Mn(0.22)O nanocubes,with a uniform size of^10 nm in edge length,have been synthesized by thermal-decomposition approach.The nanocubes exhibited superparamagnetic properties at room temperature,associated with a magnetization of 12.6 emu/g.These Fe(0.78)Mn(0.22)O nanocubes present transversal(r2)and longitudinal(r1)relaxivities of 325.9 and 0.518 mM^-1 s^-1 at 7 T for water protons.The ratio of the r2/r1(629.2)ranks them being the highest sensitivity(r2/r1)comparable to currently reported T2-weighted magnetic resonance imaging(MRI)agents.Meanwhile,the Fe(0.78)Mn(0.22)O nanocubes were functionalized and demonstrated to be biocompatible when attached to the surface of mesenchymal stem cells,therefore showing the promise as a new class of MRI agents in clinic applications.展开更多
基金supported by the National Natural Science Foundation of China (61604131,62025403)the Natural Science Foundation of Zhejiang Province (LY19F040009)+1 种基金the Fundamental Research Funds of Zhejiang SciTech University (23062120-Y)the Open Project of Key Laboratory of Solar Energy Utilization and Energy Saving Technology of Zhejiang Province (ZJS-OP-2020-07)
文摘Formamidine lead triiodide(FAPbI_(3))perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency(PCE).However,random nucleation,phase transition,and lattice defects are still the key challenges limiting the quality of FAPbI_(3) films.Previous studies show that the introduction or adding of seeds in the precursor is effective to promote the nucleation and crystallization of perovskite films.Nevertheless,the seed-assisted approach focuses on heterogeneous seeds or hetero-composites,which inevitably induce a lattice-mismatch,the genera-tion of strain or defects,and the phase segregation in the perovskite films.Herein,we first demonstrate that high-quality perovskite films are controllably prepared using α-and δ-phases mixed FAPbI_(3) micro-crystal as the homogeneous seeds with the one-step antisolvent method.The partially dissolved seeds with suitable sizes improve the crystallinity of the perovskite flm with preferable orientation,improved carrier lifetime,and increased carrier mobility.More importantly,the α-phase-containing seeds promote the formation of α-phase FAPbI_(3) films,leading to the reduction of residual lattice strain and the suppres-sion of I-ion migration.Besides,the adding of dimethyl 2,6-pyridine dicarboxylate(DPD)into the pre-cursor further suppresses the generation of defects,contributing to the PCE of devices prepared in air ambient being significantly improved to 23.75%,among the highest PCEs for fully air-processed FAPbI_(3) solar cells.The unpackaged target devices possess a high stability,maintaining 80%of the initial PCE under simulated solar illumination exceeding 800 h.
基金Supported by National Key R&D Plan(2017YFC0405201,2018YFC0407404)Achievements Transformation Project of China Institute of Water Resources and Hydropower Research(SE10003A012017)
文摘There are many reservoirs in China,and serious reservoir sedimentation affects reservoir function and reservoir safety.It is of great significance for restoring the reservoir capacity,improving the efficiency of the reservoir and prolonging the service life of the reservoir to carry out the research on reservoir sedimentation control and storage capacity recovery technology,in the case of fewer and fewer good dam sites suitable for the construction of the reservoir and the increasing accumulation of reservoir sedimentation.In this paper,influence factor of the storage loss,sedimentation control and reservoir capacity recovery technology in China are briefly reviewed.It is necessary to carry out research work on reservoir sedimentation investigation and reservoir siltation mechanism and control measures.
基金supported by the National Natural Science Foundation of China,China(No.52202232)the JST Mirai Program,Japan(No.JPMJMI19A1)+2 种基金the Natural Science Foundation of Hubei Province,China(No.2022CFB937)the Guangdong Basic and Applied Basic Research Foundation,China(No.2020A1515110251)the CAS Key Laboratory of Cryogenics,TIPC,China(No.CRYO202204).
文摘Thermoelectrics has played a fascinating role in the developments of direct energy conversion technologies.Over the past decade,sulfur-based thermoelectric materials have been significantly advanced in optimizing electrical and thermal transport due to their similarities in chemical and structural properties with tellurides and selenides.This review provides research progress on metal sulfides,particularly focuses on materials exhibiting high thermoelectric figure of merit(ZT>1.0).It highlights the potential compounds,e.g.Cu-S,Sn-S,Pb-S based,and polysulfides.Great strategies of superionic conducting,band configuration tuning,high-entropy alloying,and anomalous harmonic scattering are try to demonstrate the performance-improved mechanisms for thermoelectric sulfides.In addition,some common synthesis recipes are briefly introduced,and thereby making potential candidates as excellent alternatives for producing thermoelectric power generators in the mid temperature.Key outcomes along with how to further improve the thermoelectric performance and promote its scale-up applications are also outlined at the end.
基金supported by funds from the Eberly College of Sciences and the Huck Institutes of the Life Sciences at the Pennsylvania State Universitythe Forestry Peak Discipline Construction Project of Fujian Agriculture and Forestry University(72202200205)。
文摘Orchidaceae(with>28,000 orchid species)are one of the two largest plant families,with economically and ecologically important species,and occupy global and diverse niches with primary distribution in rainforests.Among orchids,70%grow on other plants as epiphytes;epiphytes contribute up to~50%of the plant diversity in rainforests and provide food and shelter for diverse animals and microbes,thereby contributing to the health of these ecosystems.Orchids account for over two-thirds of vascular epiphytes and provide an excellent model for studying evolution of epiphytism.Extensive phylogenetic studies of Orchidaceae and subgroups have;been crucial for understanding relationships among many orchid lineages,although some uncertainties remain.For example,in the largest subfamily Epidendroideae with nearly all epiphytic orchids,relationships among some tribes and many subtribes are still controversial,hampering evolutionary analyses of epiphytism.Here we obtained 1,450 low-copy nuclear genes from 610 orchid species,including 431 with newly generated transcriptomes,and used them for the reconstruction of robust Orchidaceae phylogenetic trees with highly supported placements of tribes and subtribes.We also provide generally wellsupported phylogenetic placements of 131 genera and 437 species that were not sampled by previous plastid and nuclear phylogenomic studies.Molecular clock analyses estimated the Orchidaceae origin at~132 million years ago(Ma)and divergences of most subtribes from 52 to 29 Ma.Character reconstruction supports at least 14 parallel origins of epiphytism;one such origin was placed at the most recent common ancestor of~95%of epiphytic orchids and linked to modern rainforests.Ten occurrences of rapid increase in the diversification rate were detected within Epidendroideae near and after the K-Pg boundary,contributing to~80%of the Orchidaceae diversity.This study provides a robust and the largest family-wide Orchidaceae nuclear phylogenetic tree thus far and new insights into the evolution of epiphytism in vascular plants.
基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB31000000)the National Natural Science Foundation of China(32122009,31870197,and 31900191)+4 种基金the National Key Research Development Program of China(2022YFF0802300 and 2022YFC2601200)the International Partnership Program of CAS(151853KYSB20190027)the Youth Innovation Promotion Association CAS(2020080)the Sino-Africa Joint Research Center,CAS International Research and Education Development Program(SAJC202101)the K.C.Wong Education Foundation(GJTD-2020-05).
文摘Establishment of a national park protection system in China,including the latest target proposed to protect at least 30%of the land area,calls for a comprehensive exploration of conservation priorities incorporating multiple diversity facets.We herein evaluate the spatial distribution of Chinese flowering plants from the perspectives of richness,uniqueness,vulnerability,and evolutionary history,by integrating three mega-phylogenies and comprehensive distribution data.We detect significantly high consistency among hotspots of different diversity measures for Chinese flowering plants,suggesting that multiple facets of evolutionary diversity are concentrically distributed in China.Affording legal protection to these areas is expected to maximize positive conservation outcomes.We propose two integrative diversity indices by incorporating three richness-based and three phylogeny-based measures,respectively.Both methods identify areas with high species richness,but the integrative phylogeny-based index also locates key areas with ancient and unique evolutionary histories(e.g.,Ailao-Wuliang Mts,Dabie Mts,Hainan rainforest,Karst area of Yunnan-Guizhou-Guangxi,Nanling Mts,and southeast coastal regions).Of all the diversity indices explored,phylogenetic endemism maximizes the incidental protection of other indices in most cases,emphasizing its significance for conservation planning.Finally,42 priority areas are identified by combining the 5%-criterion hotspots of two integrative indices and the minimum area to protect all threatened species analyzed.These priorities cover only 13.3%of China's land area,but host 97.1%of species richness(23,394/24,095),96.5%of endemic species(11,841/12,274),100%of threatened species(2,613/2,613),and 99.3%of phylogenetic diversity for flowering plants involved in this study.These frameworks provide a solid scientific basis for national park planning in China.
基金Basic Science Center Project of NSFC,Grant/Award Number:51788104National Key R&D Program of China,Grant/Award Number:2018YFB0703603。
文摘Isobaric specific heat capacity(Cp)is an important parameter not only in physics but also for most materials.Its accurate measurement is particularly critical for performance evaluation of thermoelectric materials,but the experiments by differential scanning calorimetry(DSC)often lead to large uncertainties in the measurements,especially at elevated temperatures.In this study,we propose a simple method to determine Cp by measuring the sound velocity(υ)based on lattice vibration and expansion theory.The relative standard error of theυis smaller than 1%,showing good accuracy and repeatability.The calculated Cp at elevated temperature(>300 K)increases slightly with increasing temperature due to the lattice expansion,which is more reasonable than the Dulong–Petit value.
基金supported by the Basic Science Center Project of the National Natural Science Foundation of China(51788104)the National Key R&D Program of China(2018YFB0703603)。
文摘Fabrication of nanoparticle-dispersed composites is an effective strategy for enhancing the performance of thermoelectric materials,and in particular SiC nanoparticles have been often used to create composites with Bi_(2)Te_(3)-based applied thermoelectric materials.However,the effect of particle size on the thermoelectric performance is unclear.This work systematically investigated the electrical and thermal properties of a series of(Bi,Sb)_(2)Te_(3)-based nanocomposites containing dispersed SiC nanoparticles of different sizes.It was found that particle size has a significant impact on the electrical properties with smaller SiC nanoparticles giving rise to higher electrical conductivity.Even though the dispersed SiC nanoparticles enhanced the Seebeck coefficient,no apparent dependence of the enhancement on the particle size was observed.It was also found that smaller SiC nanoparticles scatter phonons to some extent while the larger nanoparticles contribute to increased thermal conductivity.Eventually,the highest ZT value of 1.12 was obtained in 30 nm-SiC dispersed sample,corresponding to an increase by 18%from 0.95 for the matrix made from commercial scraps,and then the ZT was further boosted to 1.33 by optimizing the matrix composition and expelling excess Te during the optimized spark plasma sintering process.This work proves that the dispersion of smaller SiC nanoparticles in p-type(Bi,Sb)_(2)Te_(3) materials is more effective than the dispersion of larger nanoparticles.In addition,it is revealed that additional compositional and/or processing optimization is vital and effective for obtaining further performance enhancement for nanocomposites of SiC nanoparticles dispersed in(Bi,Sb)_(2)Te_(3).
基金supported financially by the National Natural Science Foundation of China (Nos.51471045,51401049 and 51471048)the National 1000-Plan for Young Scholars and the Start-up Funding from the Northeastern University of Chinathe Fundamental Research Funds for the Central Universities (No. N160208001)
文摘Wüstite-type Fe(0.78)Mn(0.22)O nanocubes,with a uniform size of^10 nm in edge length,have been synthesized by thermal-decomposition approach.The nanocubes exhibited superparamagnetic properties at room temperature,associated with a magnetization of 12.6 emu/g.These Fe(0.78)Mn(0.22)O nanocubes present transversal(r2)and longitudinal(r1)relaxivities of 325.9 and 0.518 mM^-1 s^-1 at 7 T for water protons.The ratio of the r2/r1(629.2)ranks them being the highest sensitivity(r2/r1)comparable to currently reported T2-weighted magnetic resonance imaging(MRI)agents.Meanwhile,the Fe(0.78)Mn(0.22)O nanocubes were functionalized and demonstrated to be biocompatible when attached to the surface of mesenchymal stem cells,therefore showing the promise as a new class of MRI agents in clinic applications.
