Aqueous rechargeable zinc ion batteries are regarded as a competitive alternative to lithium-ion batteries because of their distinct advantages of high security,high energy density,low cost,and environmental friendlin...Aqueous rechargeable zinc ion batteries are regarded as a competitive alternative to lithium-ion batteries because of their distinct advantages of high security,high energy density,low cost,and environmental friendliness.However,deep-seated problems including Zn dendrite and adverse side reactions severely impede the practical application.In this work,we proposed a freestanding Zn-electrolyte interfacial layer composed of multicapsular carbon fibers(MCFs)to regulate the plating/stripping behavior of Zn anodes.The versatile MCFs protective layer can uniformize the electric field and Zn^(2+)flux,meanwhile,reduce the deposition overpotentials,leading to high-quality and rapid Zn deposition kinetics.Furthermore,the bottom-up and uniform deposition of Zn on the Zn-MCFs interface endows long-term and high-capacity plating.Accordingly,the Zn@MCFs symmetric batteries can keep working up to 1500 h with 5 mAh cm^(−2).The feasibility of the MCFs interfacial layer is also convinced in Zn@MCFs||MnO_(2) batteries.Remarkably,the Zn@MCFs||α-MnO_(2)batteries deliver a high specific capacity of 236.1 mAh g^(−1)at 1 A g^(−1)with excellent stability,and maintain an exhilarating energy density of 154.3 Wh kg^(−1) at 33%depth of discharge in pouch batteries.展开更多
Detailed research on China's CO_(2) emission pathway of the 2030 peak and 2060 carbon neutrality goals is fundamental to promote China's climate change action.Previous studies on emission pathways have been ba...Detailed research on China's CO_(2) emission pathway of the 2030 peak and 2060 carbon neutrality goals is fundamental to promote China's climate change action.Previous studies on emission pathways have been based on long-term emission data or model analyses.However,few studies have achieved synergy and pathway optimization at both the micro and macro levels or focused on China's 2060 carbon neutrality goal,making it difficult to support the systematic management of national and regional emission pathways.In this study,we developed an integrated CO_(2) emission pathway model,the Chinese Academy of Environmental Planning Carbon Pathways 1.2 model,under China's climate change goals.Our pathway coupled the top-down and bottom-up approaches and conducted optimization analysis under social fairness and optimal cost conditions.The results provide a clear CO_(2) emission pathway and offer insights for implementing fine management of CO_(2) emissions at the national,regional,sectoral,and spatial gridded levels.展开更多
The recent advancements in thermoelectric materials are largely credited to two factors,namely established physical theories and advanced materials engineering methods.The developments in the physical theories have co...The recent advancements in thermoelectric materials are largely credited to two factors,namely established physical theories and advanced materials engineering methods.The developments in the physical theories have come a long way from the“phonon glass electron crystal”paradigm to the more recent band convergence and nanostructuring,which consequently results in drastic improvement in the thermoelectric figure of merit value.On the other hand,the progresses in materials fabrication methods and processing technologies have enabled the discovery of new physical mechanisms,hence further facilitating the emergence of high-performance thermoelectric materials.In recent years,many comprehensive review articles are focused on various aspects of thermoelectrics ranging from thermoelectric materials,physical mechanisms and materials process techniques in particular with emphasis on solid state reactions.While bottom-up approaches to obtain thermoelectric materials have widely been employed in thermoelectrics,comprehensive reviews on summarizing such methods are still rare.In this review,we will outline a variety of bottom-up strategies for preparing high-performance thermoelectric materials.In addition,state-of-art,challenges and future opportunities in this domain will be commented.展开更多
Three-dimensional(3 D)frameworks have received much attention as an effective modification strategy for next-generation high-energy-density lithium metal batteries.However,the top-growth mode of lithium(Li)on the 3 D ...Three-dimensional(3 D)frameworks have received much attention as an effective modification strategy for next-generation high-energy-density lithium metal batteries.However,the top-growth mode of lithium(Li)on the 3 D framework remains a tough challenge.To achieve a uniform bottom-up Li growth,a scheme involving Ag concentration gradient in 3 D PVDF framework(C-Ag/PVDF)is proposed.Ag nanoparticles with a concentration gradient induce an interface activity gradient in the 3 D framework,and this gradient feature is still maintained during the cycle.As a result,the C-Ag/PVDF framework delivers a long lifespan over 1800 h at a current density of 1 mA cm^(-2) with a capacity of 1 mAh cm^(-2),and shows an ultra-long life(>1300 h)even at a high current density of 4 mA cm^(-2) with a capacity of 4 mAh cm^(-2).The advantage of concentration gradient provides further insights into the optimal design of the 3 D framework for stable Li metal anode.展开更多
Ribosomes are abundant,large RNA-protein complexes that are the sites of all protein synthesis in cells.Defects in ribosomal proteins(RPs),including proteoforms arising from genetic variations,alternative splicing of ...Ribosomes are abundant,large RNA-protein complexes that are the sites of all protein synthesis in cells.Defects in ribosomal proteins(RPs),including proteoforms arising from genetic variations,alternative splicing of RNA transcripts,post-translational modifications and alterations of protein expression level,have been linked to a diverse range of diseases,including cancer and aging.Comprehensive characterization of ribosomal proteoforms is challenging but important for the discovery of potential disease biomarkers or protein targets.In the present work,using E.coli 70S RPs as an example,we first developed a top-down proteomics approach on a Waters Synapt G2 Si mass spectrometry(MS)system,and then applied it to the HeLa 80S ribosome.The results were complemented by a bottom-up approach.In total,50 out of 55 RPs were identified using the top-down approach.Among these,more than 30 RPs were found to have their N-terminal methionine removed.Additional modifications such as methylation,acetylation,and hydroxylation were also observed,and the modification sites were identified by bottomup MS.In a HeLa 80S ribosomal sample,we identified 98 ribosomal proteoforms,among which multiple truncated 80S ribosomal proteoforms were observed,the type of information which is often overlooked by bottom-up experiments.Although their relevance to diseases is not yet known,the integration of topdown and bottom-up proteomics approaches paves the way for the discovery of proteoform-specific disease biomarkers or targets.展开更多
In this paper, a fast and accurate work-piece detection and measurement algorithm is proposed based on top-down feature extraction and bottom-up saliency estimation. Firstly, a top-down feature extraction method based...In this paper, a fast and accurate work-piece detection and measurement algorithm is proposed based on top-down feature extraction and bottom-up saliency estimation. Firstly, a top-down feature extraction method based on the prior knowledge of work- pieces is presented, in which the contour of a work-piece is chosen as the major feature and the corresponding template of the edges is created. Secondly, a bottom-up salient region estimation algorithm is proposed, where the image boundaries are labelled as background queries, and the salient region can be detected by computing contrast against image boundary. Finally, the calibration method for vision system with telecentric lens is discussed, and the dimensions of the work-pieces are measured. In addition, strategies such as image pyramids and a stopping criterion are adopted to speed-up the algorithm. An automatic system embedded with the proposed detection and measurement algorithm combining top-down and bottom-up saliency （DM-TBS） is designed to pick out defective work-pieces without any manual auxiliary. Experiments and results demonstrate the effectiveness of the proposed method.展开更多
Much attention is being given to estimating cement-related CO2 emissions in China. However, scant explicit and systematical exploration is being done on regional and national CO2 emission volumes. The aim of this work...Much attention is being given to estimating cement-related CO2 emissions in China. However, scant explicit and systematical exploration is being done on regional and national CO2 emission volumes. The aim of this work is therefore to provide an improved bottom-up spatial-integration system, relevant to CO2 emissions at factory level, to allow a more accurate estimation of the CO2 emissions from cement production. Based on this system, the sampling data of cement production lines were integrated as regional- and national-level information. The integration results showed that each ton of clinker produced 883 kg CO2, of which the process, fuel, and electricity emissions accounted for 58.70%, 35.97%, and 5.33%, respectively. The volume of CO2 emissions from clinker and cement production reached 1202 Mt and 1284 Mt, respectively, in 2013. A discrepancy was identified between the clinker emission factors relevant to the two main production processes （i.e., the new suspension preheating and pre-calcining kiln （NSP） and the vertical shaft kiln （VSK））, probably relevant to the energy efficiency of the two technologies. An analysis of the spatial characteristics indi- cated that the spatial distribution of the clinker emission factors mainly corresponded to that of the NSP process. The discrepancy of spatial pattern largely complied with the economic and population distribution pattern of China. The study could fill the knowledge gaps and provide role players with a useful spatial integration system that should facilitate the accurate estimation of carbon and corresponding regional mitigation strategies in China.展开更多
The defects from electron transport layer,perovskite layer and their interface would result in carrier nonradiative recombination losses.Poor buried interfacial contact is detrimental to charge extraction and device s...The defects from electron transport layer,perovskite layer and their interface would result in carrier nonradiative recombination losses.Poor buried interfacial contact is detrimental to charge extraction and device stability.Here,we report a bottom-up holistic carrier management strategy induced synergistically by multiple chemical bonds to minimize bulk and interfacial energy losses for high-performance perovskite photovoltaics.4-trifluoromethyl-benzamidine hydrochloride(TBHCl)containing–CF_(3),amidine cation and Cl^(-)is in advance incorporated into SnO_(2)colloid solution to realize bottom-up modification.The synergistic effect of multiple functional groups and multiple-bond-induced chemical interaction are revealed theoretically and experimentally.F and Cl^(-)can passivate oxygen vacancy and/or undercoordinated Sn^(4+)defects by coordinating with Sn^(4+).The F can suppress cation migration and modulate crystallization via hydrogen bond with FA^(+),and can passivate lead defects by coordinating with Pb^(2+).The–NH_(2)–C=NH^(+)_(2)and Cl^(-)can passivate cation and anion vacancy defects through ionic bonds with perovskites,respectively.Through TBHCl modification,the suppression of agglomeration of SnO_(2)nanoparticles,bulk and interfacial defect passivation,and release of tensile strains of perovskite films are demonstrated,which resulted in a PCE enhancement from 21.28%to 23.40%and improved stability.With post-treatment,the efficiency is further improved to 23.63%.展开更多
This paper mainly deals with two mainstreams in teaching listening comprehension:bottom-up processing approach and top-down processing approach.In the first part of the essay the importance of listening comprehension ...This paper mainly deals with two mainstreams in teaching listening comprehension:bottom-up processing approach and top-down processing approach.In the first part of the essay the importance of listening comprehension in language learning will be demonstrated briefly.Then the author will go on to explore the nature of top-down and bottom-up approaches in teaching listening.Lastly,at the third part of the essay,the author shall try to discuss the possibility of applying these approaches into practice,that is,when and why one of them is more useful.Furthermore in this section,a more integrated view will be introduced.展开更多
Traditional approach to evaluate the impacts of climate change on the water resources systems always begins with downscaling general circulation models( GCMs) and proceeding back to the hydrological model. This approa...Traditional approach to evaluate the impacts of climate change on the water resources systems always begins with downscaling general circulation models( GCMs) and proceeding back to the hydrological model. This approach has some distinct disadvantages: 1) GCM must be downscaled; 2) different GCMs are difficult to be reconciled for a given climate change scenario;3) the uncertainty of GCMs is far from the requirement of the evaluation of climate change impacts. To overcome these limits of the traditional method,a new method termed as "bottom-up"was used for climate risk assessment that linked vulnerability assessment with climate information to assess the risk of climate change impacts on the Quabbin Reservoir,and United States under A2 scenario.The result shows that the risks are around 20% in 2006-2035 and 2036-2055,50% in 2066-2095.展开更多
Top-down and bottom-up processes are two popularly-used method in teaching listening,but each of them has deficiencies.This essay will attempt to demonstrate that both top-down process and bottom-up process are necess...Top-down and bottom-up processes are two popularly-used method in teaching listening,but each of them has deficiencies.This essay will attempt to demonstrate that both top-down process and bottom-up process are necessarily useful,and adopting them appropriately conduce to effective and efficient listening comprehension.The first section of this paper will critically examine the advantages and disadvantages of the two processes.It will then illustrate the benefit of employing them in an interactive way.展开更多
基金supported by the National Natural Science Foundation of China(51901206)“the Fundamental Research Funds for the Central Universities”(2021QNA4003).
文摘Aqueous rechargeable zinc ion batteries are regarded as a competitive alternative to lithium-ion batteries because of their distinct advantages of high security,high energy density,low cost,and environmental friendliness.However,deep-seated problems including Zn dendrite and adverse side reactions severely impede the practical application.In this work,we proposed a freestanding Zn-electrolyte interfacial layer composed of multicapsular carbon fibers(MCFs)to regulate the plating/stripping behavior of Zn anodes.The versatile MCFs protective layer can uniformize the electric field and Zn^(2+)flux,meanwhile,reduce the deposition overpotentials,leading to high-quality and rapid Zn deposition kinetics.Furthermore,the bottom-up and uniform deposition of Zn on the Zn-MCFs interface endows long-term and high-capacity plating.Accordingly,the Zn@MCFs symmetric batteries can keep working up to 1500 h with 5 mAh cm^(−2).The feasibility of the MCFs interfacial layer is also convinced in Zn@MCFs||MnO_(2) batteries.Remarkably,the Zn@MCFs||α-MnO_(2)batteries deliver a high specific capacity of 236.1 mAh g^(−1)at 1 A g^(−1)with excellent stability,and maintain an exhilarating energy density of 154.3 Wh kg^(−1) at 33%depth of discharge in pouch batteries.
基金The research was funded by the project“An Emission Scenario Air Quality Model Based Study on the Evaluation of‘Dual Attainments’of Chinese City”[Grant number.72074154],supported by the National Natural Science Foundation of China.
文摘Detailed research on China's CO_(2) emission pathway of the 2030 peak and 2060 carbon neutrality goals is fundamental to promote China's climate change action.Previous studies on emission pathways have been based on long-term emission data or model analyses.However,few studies have achieved synergy and pathway optimization at both the micro and macro levels or focused on China's 2060 carbon neutrality goal,making it difficult to support the systematic management of national and regional emission pathways.In this study,we developed an integrated CO_(2) emission pathway model,the Chinese Academy of Environmental Planning Carbon Pathways 1.2 model,under China's climate change goals.Our pathway coupled the top-down and bottom-up approaches and conducted optimization analysis under social fairness and optimal cost conditions.The results provide a clear CO_(2) emission pathway and offer insights for implementing fine management of CO_(2) emissions at the national,regional,sectoral,and spatial gridded levels.
基金The authors acknowledge support from A*STAR’s Science and Engineering Research Council,PHAROS program on Hybrid Thermoelectrics for Ambient Applications(Grant Nos.:1527200019,1527200020 and 1527200021)Agritech program on Sustainable Hybrid Lighting System for Controlled Environment Agriculture:A19D9a0096.
文摘The recent advancements in thermoelectric materials are largely credited to two factors,namely established physical theories and advanced materials engineering methods.The developments in the physical theories have come a long way from the“phonon glass electron crystal”paradigm to the more recent band convergence and nanostructuring,which consequently results in drastic improvement in the thermoelectric figure of merit value.On the other hand,the progresses in materials fabrication methods and processing technologies have enabled the discovery of new physical mechanisms,hence further facilitating the emergence of high-performance thermoelectric materials.In recent years,many comprehensive review articles are focused on various aspects of thermoelectrics ranging from thermoelectric materials,physical mechanisms and materials process techniques in particular with emphasis on solid state reactions.While bottom-up approaches to obtain thermoelectric materials have widely been employed in thermoelectrics,comprehensive reviews on summarizing such methods are still rare.In this review,we will outline a variety of bottom-up strategies for preparing high-performance thermoelectric materials.In addition,state-of-art,challenges and future opportunities in this domain will be commented.
基金supported by the Fundamental Research Funds for the Central Universities,China(ZYGX2019Z008)the National Natural Science Foundation of China(52072061)the Open Fund of the Key Laboratory for Renewable Energy,Chinese Academy of Sciences,Beijing Key Laboratory for New Energy Materials and Devices。
文摘Three-dimensional(3 D)frameworks have received much attention as an effective modification strategy for next-generation high-energy-density lithium metal batteries.However,the top-growth mode of lithium(Li)on the 3 D framework remains a tough challenge.To achieve a uniform bottom-up Li growth,a scheme involving Ag concentration gradient in 3 D PVDF framework(C-Ag/PVDF)is proposed.Ag nanoparticles with a concentration gradient induce an interface activity gradient in the 3 D framework,and this gradient feature is still maintained during the cycle.As a result,the C-Ag/PVDF framework delivers a long lifespan over 1800 h at a current density of 1 mA cm^(-2) with a capacity of 1 mAh cm^(-2),and shows an ultra-long life(>1300 h)even at a high current density of 4 mA cm^(-2) with a capacity of 4 mAh cm^(-2).The advantage of concentration gradient provides further insights into the optimal design of the 3 D framework for stable Li metal anode.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.:91953102 and 81872836)Natural Science Foundation of Guangdong Province,China(Grant Nos.:2019A1515011265 and 2022A1515010965)+1 种基金the Fundamental Research Funds for Sun Yat-sen University,China(Grant No.:19ykzd26)Open Project Funding of the State Key Laboratory of Crop Stress Adaptation and Improvement(Grant No.:2020KF05).Huilin Li would like to thank the Pearl River Talent Recruitment Program for support.
文摘Ribosomes are abundant,large RNA-protein complexes that are the sites of all protein synthesis in cells.Defects in ribosomal proteins(RPs),including proteoforms arising from genetic variations,alternative splicing of RNA transcripts,post-translational modifications and alterations of protein expression level,have been linked to a diverse range of diseases,including cancer and aging.Comprehensive characterization of ribosomal proteoforms is challenging but important for the discovery of potential disease biomarkers or protein targets.In the present work,using E.coli 70S RPs as an example,we first developed a top-down proteomics approach on a Waters Synapt G2 Si mass spectrometry(MS)system,and then applied it to the HeLa 80S ribosome.The results were complemented by a bottom-up approach.In total,50 out of 55 RPs were identified using the top-down approach.Among these,more than 30 RPs were found to have their N-terminal methionine removed.Additional modifications such as methylation,acetylation,and hydroxylation were also observed,and the modification sites were identified by bottomup MS.In a HeLa 80S ribosomal sample,we identified 98 ribosomal proteoforms,among which multiple truncated 80S ribosomal proteoforms were observed,the type of information which is often overlooked by bottom-up experiments.Although their relevance to diseases is not yet known,the integration of topdown and bottom-up proteomics approaches paves the way for the discovery of proteoform-specific disease biomarkers or targets.
基金supported by National Natural Science Foundation of China(Nos.61379097,91748131,61771471,U1613213 and 61627808)National Key Research and Development Plan of China(No.2017YFB1300202)Youth Innovation Promotion Association Chinese Academy of Sciences(CAS)(No.2015112)
文摘In this paper, a fast and accurate work-piece detection and measurement algorithm is proposed based on top-down feature extraction and bottom-up saliency estimation. Firstly, a top-down feature extraction method based on the prior knowledge of work- pieces is presented, in which the contour of a work-piece is chosen as the major feature and the corresponding template of the edges is created. Secondly, a bottom-up salient region estimation algorithm is proposed, where the image boundaries are labelled as background queries, and the salient region can be detected by computing contrast against image boundary. Finally, the calibration method for vision system with telecentric lens is discussed, and the dimensions of the work-pieces are measured. In addition, strategies such as image pyramids and a stopping criterion are adopted to speed-up the algorithm. An automatic system embedded with the proposed detection and measurement algorithm combining top-down and bottom-up saliency （DM-TBS） is designed to pick out defective work-pieces without any manual auxiliary. Experiments and results demonstrate the effectiveness of the proposed method.
基金Strategic Priority Research Programs-Climate Change： Carbon Budget and Related Issues of the Chinese Academy of Sciences, Grant No.XDA 05010400, No.XDA 05010205 National Natural Science Foundation of China, No.4117111Acknowledgements We thank Dr LIU Tiejun, Dr XU Chengdong, Dr GAO Tianming and Dr ZHONG Shuai for their great support during data calculation process, and thank the editors and two anonymous reviewers for their constructive comments on the manuscript.
文摘Much attention is being given to estimating cement-related CO2 emissions in China. However, scant explicit and systematical exploration is being done on regional and national CO2 emission volumes. The aim of this work is therefore to provide an improved bottom-up spatial-integration system, relevant to CO2 emissions at factory level, to allow a more accurate estimation of the CO2 emissions from cement production. Based on this system, the sampling data of cement production lines were integrated as regional- and national-level information. The integration results showed that each ton of clinker produced 883 kg CO2, of which the process, fuel, and electricity emissions accounted for 58.70%, 35.97%, and 5.33%, respectively. The volume of CO2 emissions from clinker and cement production reached 1202 Mt and 1284 Mt, respectively, in 2013. A discrepancy was identified between the clinker emission factors relevant to the two main production processes （i.e., the new suspension preheating and pre-calcining kiln （NSP） and the vertical shaft kiln （VSK））, probably relevant to the energy efficiency of the two technologies. An analysis of the spatial characteristics indi- cated that the spatial distribution of the clinker emission factors mainly corresponded to that of the NSP process. The discrepancy of spatial pattern largely complied with the economic and population distribution pattern of China. The study could fill the knowledge gaps and provide role players with a useful spatial integration system that should facilitate the accurate estimation of carbon and corresponding regional mitigation strategies in China.
基金financially supported by the Support Plan for Overseas Students to Return to China for Entrepreneurship and Innovation(cx2020003)the Fundamental Research Funds for the Central Universities(2020CDJ-LHZZ-074)the Natural Science Foundation of Chongqing(cstc2020jcyj-msxm X0629)。
文摘The defects from electron transport layer,perovskite layer and their interface would result in carrier nonradiative recombination losses.Poor buried interfacial contact is detrimental to charge extraction and device stability.Here,we report a bottom-up holistic carrier management strategy induced synergistically by multiple chemical bonds to minimize bulk and interfacial energy losses for high-performance perovskite photovoltaics.4-trifluoromethyl-benzamidine hydrochloride(TBHCl)containing–CF_(3),amidine cation and Cl^(-)is in advance incorporated into SnO_(2)colloid solution to realize bottom-up modification.The synergistic effect of multiple functional groups and multiple-bond-induced chemical interaction are revealed theoretically and experimentally.F and Cl^(-)can passivate oxygen vacancy and/or undercoordinated Sn^(4+)defects by coordinating with Sn^(4+).The F can suppress cation migration and modulate crystallization via hydrogen bond with FA^(+),and can passivate lead defects by coordinating with Pb^(2+).The–NH_(2)–C=NH^(+)_(2)and Cl^(-)can passivate cation and anion vacancy defects through ionic bonds with perovskites,respectively.Through TBHCl modification,the suppression of agglomeration of SnO_(2)nanoparticles,bulk and interfacial defect passivation,and release of tensile strains of perovskite films are demonstrated,which resulted in a PCE enhancement from 21.28%to 23.40%and improved stability.With post-treatment,the efficiency is further improved to 23.63%.
文摘This paper mainly deals with two mainstreams in teaching listening comprehension:bottom-up processing approach and top-down processing approach.In the first part of the essay the importance of listening comprehension in language learning will be demonstrated briefly.Then the author will go on to explore the nature of top-down and bottom-up approaches in teaching listening.Lastly,at the third part of the essay,the author shall try to discuss the possibility of applying these approaches into practice,that is,when and why one of them is more useful.Furthermore in this section,a more integrated view will be introduced.
基金National Natural Science Foundation of China(No.40971026)Key State Lab of Urban Water Resource and Environment,China(No.ES201109)+1 种基金National Science and Technology Infrastructure Program,China(No.2012BAC19B05-4)Natural Science Foundation of Jilin Province,China(No.20130101085JC)
文摘Traditional approach to evaluate the impacts of climate change on the water resources systems always begins with downscaling general circulation models( GCMs) and proceeding back to the hydrological model. This approach has some distinct disadvantages: 1) GCM must be downscaled; 2) different GCMs are difficult to be reconciled for a given climate change scenario;3) the uncertainty of GCMs is far from the requirement of the evaluation of climate change impacts. To overcome these limits of the traditional method,a new method termed as "bottom-up"was used for climate risk assessment that linked vulnerability assessment with climate information to assess the risk of climate change impacts on the Quabbin Reservoir,and United States under A2 scenario.The result shows that the risks are around 20% in 2006-2035 and 2036-2055,50% in 2066-2095.
文摘Top-down and bottom-up processes are two popularly-used method in teaching listening,but each of them has deficiencies.This essay will attempt to demonstrate that both top-down process and bottom-up process are necessarily useful,and adopting them appropriately conduce to effective and efficient listening comprehension.The first section of this paper will critically examine the advantages and disadvantages of the two processes.It will then illustrate the benefit of employing them in an interactive way.
