Influences of off-state overdrive stress on the fluorine-plasma treated AlGaN/GaN high-electronic mobility transistors(HEMTs)are experimentally investigated.It is observed that the reverse leakage current between the ...Influences of off-state overdrive stress on the fluorine-plasma treated AlGaN/GaN high-electronic mobility transistors(HEMTs)are experimentally investigated.It is observed that the reverse leakage current between the gate and source decreases after the off-state stress,whereas the current between the gate and drain increases.By analyzing those changes of the reverse currents based on the Frenkel–Poole model,we realize that the ionization of fluorine ions occurs during the off-state stress.Furthermore,threshold voltage degradation is also observed after the off-state stress,but the degradations of AlGaN/GaN HEMTs treated with different F-plasma RF powers are different.By comparing the differences between those devices,we find that the F-ions incorporated in the GaN buffer layer play an important role in averting degradation.Lastly,suggestions to obtain a more stable fluorine-plasma treated AlGaN/GaN HEMT are put forwarded.展开更多
This paper gives a definition of the Industrial Internet and expounds on the academic connotation of the future Industrial Internet.From this foundation,we outline the development and current status of the Industrial ...This paper gives a definition of the Industrial Internet and expounds on the academic connotation of the future Industrial Internet.From this foundation,we outline the development and current status of the Industrial Internet in China and globally.Moreover,we detail the avant-garde paradigms encompassed within the National Natural Science Foundation of China(NSFC)’s“Future Industrial Internet Fundamental Theory and Key Technologies”research plan and its corresponding management strategies.This research initiative endeavors to enhance interdisciplinary collaborations,aiming for a synergistic alignment of industry,academia,research,and practical implementations.The primary focus of the research plan is on the pivotal scientific challenges inherent to the future industrial internet.It is poised to traverse the“first mile”,encompassing foundational research and pioneering innovations specific to the industrial internet,and seamlessly bridges to the“last mile”,ensuring the effective commercialization of scientific and technological breakthroughs into tangible industrial market applications.The anticipated contributions from this initiative are projected to solidify both the theoretical and practical scaffolding essential for the cultivation of a globally competitive industrial internet infrastructure in China.展开更多
The Convention on Biological Diversity seeks to conserve at least 30%of global land and water areas by 2030,which is a challenge but also an opportunity to better preserve biodiversity,including flowering plants(angio...The Convention on Biological Diversity seeks to conserve at least 30%of global land and water areas by 2030,which is a challenge but also an opportunity to better preserve biodiversity,including flowering plants(angiosperms).Herein,we compiled a large database on distributions of over 300,000 angiosperm species and the key functional traits of 67,024 species.Using this database,we constructed biodiversity-environment models to predict global patterns of taxonomic,phylogenetic,and functional diversity in terrestrial angiosperms and provide a comprehensive mapping of the three diversity facets.We further evaluated the current protection status of the biodiversity centers of these diversity facets.Our results showed that geographical patterns of the three facets of plant diversity exhibited substantial spatial mismatches and nonoverlapping conservation priorities.Idiosyncratic centers of functional diversity,particularly of herbaceous species,were primarily distributed in temperate regions and under weaker protection compared with other biodiversity centers of taxonomic and phylogenetic facets.Our global assessment of multifaceted biodiversity patterns and centers highlights the insufficiency and unbalanced conservation among the three diversity facets and the two growth forms(woody vs.herbaceous),thus providing directions for guiding the future conservation of global plant diversity.展开更多
Global climate change has led to the decline of species and functional diversity in ecosystems,changing community composition and ecosystem functions.However,we still know little about how species with different resou...Global climate change has led to the decline of species and functional diversity in ecosystems,changing community composition and ecosystem functions.However,we still know little about how species with different resource-use strategies(different types of resource usage and plant growth of plants as indicated by the spectrum of plant economic traits,including acquisitive resource-use strategy and conservative resource-use strategy)would change in response to climate change,and how the changes in the diversity of species with different resource-use strategies may influence community-level productivity.Here,using long-term(1982–2017)observatory data in a temperate grassland in Inner Mongolia,we investigated how climate change had affected the species richness(SR)and functional richness(FRic)for the whole community and for species with different resource-use strategies.Specifically,based on data for four traits representing leaf economics spectrum(leaf carbon concentration,leaf nitrogen concentration,leaf phosphorus concentration,and specific leaf area),we divided 81 plant species appearing in the grassland community into three plant functional types representing resource-acquisitive,medium,and resource-conservative species.We then analyzed the changes in community-level productivity in response to the decline of SR and FRic at the community level and for different resource-use strategies.We found that community-level SR and FRic decreased with drying climate,which was largely driven by the decline of diversity for resource-acquisitive species.However,community-level productivity remained stable because resource-conservative species dominating this grassland were barely affected by climate change.Our study revealed distinctive responses of species with different resource-use strategies to climate change and provided a new approach based on species functional traits for predicting the magnitude and direction of climate change effects on ecosystem functions.展开更多
Flowering phenology of plants,which is important for reproductive growth,has been shown to be influenced by climate change.Understanding how flowering phenology responds to climate change and exploring the variation o...Flowering phenology of plants,which is important for reproductive growth,has been shown to be influenced by climate change.Understanding how flowering phenology responds to climate change and exploring the variation of this response across plant groups can help predict structural and functional changes in plant communities in response to ongoing climate change.Here,we used long-term collections of 33 flowering plant species from the Gongga Mountains(Mt.Gongga hereafter),a biodiversity hotspot,to investigate how plant flowering phenology changed over the past 70 years in response to climate change.We found that mean flowering times in Mt.Gongga were delayed in all vegetation types and elevations over the last 70 years.Furthermore,flowering time was delayed more in lowlands than at high elevations.Interestingly,we observed that spring-flowering plants show earlier flowering times whereas summer/autumn plants show delayed flowering times.Non-synchronous flowering phenology across species was mainly driven by changes in temperature and precipitation.We also found that the flowering phenology of 78.8%plant species was delayed in response to warming temperatures.Our findings also indicate that the magnitude and direction of variation in plant flowering times vary significantly among species along elevation gradients.Shifts in flowering time might cause trophic mismatches with co-occurring and related species,affecting both forest ecosystem structure and function.展开更多
Background:Lung cancer is the most commonly diagnosed cancer worldwide.Its survival rate can be significantly improved by early screening.Biomarkers based on radiomics features have been found to provide important phy...Background:Lung cancer is the most commonly diagnosed cancer worldwide.Its survival rate can be significantly improved by early screening.Biomarkers based on radiomics features have been found to provide important physiological information on tumors and considered as having the potential to be used in the early screening of lung cancer.In this study,we aim to establish a radiomics model and develop a tool to improve the discrimination between benign and malignant pulmonary nodules.Methods:A retrospective study was conducted on 875 patients with benign or malignant pulmonary nodules who underwent computed tomography(CT)examinations between June 2013 and June 2018.We assigned 612 patients to a training cohort and 263 patients to a validation cohort.Radiomics features were extracted from the CT images of each patient.Least absolute shrinkage and selection operator(LASSO)was used for radiomics feature selection and radiomics score calculation.Multivariate logistic regression analysis was used to develop a classification model and radiomics nomogram.Radiomics score and clinical variables were used to distinguish benign and malignant pulmonary nodules in logistic model.The performance of the radiomics nomogram was evaluated by the area under the curve(AUC),calibration curve and Hosmer-Lemeshow test in both the training and validation cohorts.Results:A radiomics score was built and consisted of 20 features selected by LASSO from 1288 radiomics features in the training cohort.The multivariate logistic model and radiomics nomogram were constructed using the radiomics score and patients’age.Good discrimination of benign and malignant pulmonary nodules was obtained from the training cohort(AUC,0.836;95%confidence interval[CI]:0.793-0.879)and validation cohort(AUC,0.809;95%CI:0.745-0.872).The Hosmer-Lemeshow test also showed good performance for the logistic regression model in the training cohort(P=0.765)and validation cohort(P=0.064).Good alignment with the calibration curve indicated the good performance of the nomogram.Conclusions:The established radiomics nomogram is a noninvasive preoperative prediction tool for malignant pulmonary nodule diagnosis.Validation revealed that this nomogram exhibited excellent discrimination and calibration capacities,suggesting its clinical utility in the early screening of lung cancer.展开更多
Aims Morphological variation of leaves is a key indicator of plant response to climatic change.Leaf size and shape are associated with carbon,water and energy exchange of plants with their environment.However,whether ...Aims Morphological variation of leaves is a key indicator of plant response to climatic change.Leaf size and shape are associated with carbon,water and energy exchange of plants with their environment.However,whether and how leaf size and shape responded to climate change over the past decades remains poorly studied.Moreover,many studies have only explored inter-but not intraspecific variation in leaf size and shape across space and time.Methods We collected>6000 herbarium specimens spanning 98 years(1910–2008)in China for seven representative dicot species and measured their leaf length and width.We explored geographical patterns and temporal trends in leaf size(i.e.leaf length,leaf width and length×width product)and shape(i.e.length/width ratio),and investigated the effects of changes in precipitation and temperature over time and space on the variation in leaf size and shape.Important Findings After accounting for the effects of sampling time,leaf size decreased with latitude for all species combined,but the relationship varied among species.Leaf size and shape were positively correlated with temperature and precipitation across space.After accounting for the effects of sampling locations,leaf size of all species combined increased with time.Leaf size changes over time were mostly positively correlated with precipitation,whereas leaf shape changes were mostly correlated with temperature.Overall,our results indicate significant spatial and temporal intraspecific variation in leaf size and shape in response to climate.Our study also demonstrates that herbarium specimens collected over a considerable period of time provide a good resource to study the impacts of climate change on plant morphological traits.展开更多
The fruit and vegetable picking has posed a great challenge on the production and markets during the harvest season.Manual picking cannot fully meet the rapid requirements of each market,mainly due to the high labor-i...The fruit and vegetable picking has posed a great challenge on the production and markets during the harvest season.Manual picking cannot fully meet the rapid requirements of each market,mainly due to the high labor-intensive and time-consuming tasks,even the aging and shortage of agricultural labor force in recent years.Alternatively,smart robotics can be an efficient solution to increase the planting areas for the markets in combination with changes in cultivation,preservation,and processing technology.However,some improvements still need to be performed on these picking robots.To document the progress in and current status of this field,this study performed a bibliometric analysis.This analysis evaluated the current performance characteristics of various fruit and vegetable picking robots for better prospects in the future.Five perspectives were proposed covering the robotic arms,end effectors,vision systems,picking environments,and picking performance for the large-scale mechanized production of fruits and vegetables in modern agriculture.The current problems of fruit and vegetable picking robots were summarized.Finally,the outlook of the fruit and vegetable picking robots prospected from four aspects:structured environment for fruit planting,the algorithm of recognition and positioning,picking efficiency,and cost-saving picking robots.This study comprehensively assesses the current research status,thus helping researchers steer their projects or locate potential collaborators.展开更多
Ce-or La-doped Cu/SSZ-13 catalysts were prepared by a hydrothermal method and Cu,Ce or La ions were incorporated through stepwise ion exchange,The catalyst activity was measured for the ammonia selective catalytic red...Ce-or La-doped Cu/SSZ-13 catalysts were prepared by a hydrothermal method and Cu,Ce or La ions were incorporated through stepwise ion exchange,The catalyst activity was measured for the ammonia selective catalytic reduction reaction.The structure and composition of catalyst were characterized by using X-ray diffraction,scanning electron microscopy,inductively coupled plasma mass spectrometry solid-state NMR,NH_(3)-TPD techniques,and the active components were examined by XPS and XANES.The results indicate that the Ce and La doping can both completely preserve the SCR activity of Cu/SSZ-13 above 300℃,but there is also a decrease of activity below 200℃.On the other hand,Ce doping is beneficial to the formation of framework aluminum,stabilizes molecular sieve framework and Cu active sites of Cu/SSZ-13,thereby improves the catalyst hydrothermal stability.But La doping will decrease the amount of framework aluminum and Cu active sites of Cu/SSZ-13 after hydrothermally aging,even destroy zeolite CHA structure.This is quite harmful to the catalyst hydrothermal stability.展开更多
Aims Plant height is a key functional trait related to aboveground bio-mass,leaf photosynthesis and plant fitness.However,large-scale geographical patterns in community-average plant height(cAPH)of woody species and d...Aims Plant height is a key functional trait related to aboveground bio-mass,leaf photosynthesis and plant fitness.However,large-scale geographical patterns in community-average plant height(cAPH)of woody species and drivers of these patterns across different life forms remain hotly debated.Moreover,whether cAPH could be used as a predictor of ecosystem primary productivity is unknown.Methods We compiled mature height and distributions of 11422 woody spe-cies in eastern Eurasia,and estimated geographic patterns in cAPH for different taxonomic groups and life forms.then we evaluated the effects of environmental(including current climate and historical climate change since the Last Glacial Maximum(LGM))and evolutionary factors on cAPH.Lastly,we compared the predictive power of cAPH on primary productivity with that of LiDAR-derived canopy-height data from a global survey.Important Findings Geographic patterns of cAPH and their drivers differed among taxonomic groups and life forms.the strongest predictor for cAPH of all woody species combined,angiosperms,all dicots and deciduous dicots was actual evapotranspiration,while temperature was the strongest pre-dictor for cAPH of monocots and tree,shrub and evergreen dicots,and water availability for gymnosperms.Historical climate change since the LGM had only weak effects on cAPH.No phylogenetic signal was detected in family-wise average height,which was also unrelated to the tested environmental factors.Finally,we found a strong correlation between cAPH and ecosystem primary productivity.Primary productivity showed a weaker relationship with cAPH of the tallest species within a grid cell and no relationship with LiDAR-derived canopy height reported in the global survey.Our findings suggest that current climate rather than historical climate change and evolutionary history determine the geographical patterns in cAPH.However,the relative effects of climatic factors representing environmental energy and water availability on spatial variations of cAPH vary among plant life forms.Moreover,our results also suggest that cAPH can be used as a good predictor of ecosystem primary productivity.展开更多
An organic compound exhibiting simultaneously reversible switch between its emission colors and luminescence mechanisms,possessing high contrast from deep blue normal fluorescence(NF) to yellow thermally activated del...An organic compound exhibiting simultaneously reversible switch between its emission colors and luminescence mechanisms,possessing high contrast from deep blue normal fluorescence(NF) to yellow thermally activated delayed fluorescence(TADF),is reported. Based on these two complementary colors, white-light emission combining NF and TADF from a single compound can be achieved in various states. Experimental results and density functional theory calculations indicate that the controllable conformational distribution under thermal and mechanical activation is the mechanism responsible for the reversible switching behavior.展开更多
The donor-n-conjugated-acceptor (D-n-A) structure is an important design for the luminescent materials be- cause of its diversity in the selections of donor, n-bridge and acceptor groups. Herein, we demonstrate two ...The donor-n-conjugated-acceptor (D-n-A) structure is an important design for the luminescent materials be- cause of its diversity in the selections of donor, n-bridge and acceptor groups. Herein, we demonstrate two examples of D-^-A structures capable to finely modulate the excited state properties and arrangement of energy levels, TPA-AN-BP and CZP-AN-BP, which possess the same acceptor and n-bridge but different donor. The investigation of their photophysical properties and DFT calculation revealed that the D-n-A structure with proper donor, n-bridge and acceptor can result in separation of frontier molecular orbitals on the corresponding donor and acceptor with an obvious overlap on the n-bridge, resulting in a hybridized local and charge-transfer (HLCT) excited state with high photoluminescent (PL) efficiencies. Meanwhile, their singlet and triplet states are arranged on corresponding moie- ties with large energy gap between T2 and T1, and a small energy gap between S1 and T2, which favor the reverse intersystem crossing (RISC) from high-lying triplet levels to singlet levels. As a result, the sky-blue emission non-doped OLED based on the TPA-AN-BP reached maximum external quantum efficiency (EQE) of 4.39% and a high exciton utilization efficiency (EUE) of 77%. This study demonstrates a new strategy to construct highly effi- cient OLED materials.展开更多
The effects of contemporary climate,habitat heterogeneity and long-term climate change on species richness are well studied for woody plants in forest ecosystems,but poorly understood for herbaceous plants,especially ...The effects of contemporary climate,habitat heterogeneity and long-term climate change on species richness are well studied for woody plants in forest ecosystems,but poorly understood for herbaceous plants,especially in alpine–arctic ecosystems.Here,we aim to test if the previously proposed hypothesis based on the richness–environment relationship could explain the variation in richness patterns of the typical alpine–arctic herbaceous genus Saxifraga.Using a newly compiled distribution database of 437 Saxifraga species,we estimated the species richness patterns for all species,narrow-and wide-ranged species.We used generalized linear models and simultaneous autoregressive models to evaluate the effects of contemporary climate,habitat heterogeneity and historical climate on species richness patterns.Partial regressions were used to determine the independent and shared effects of different variables.Four widely used models were tested to identify their predictive power in explaining patterns of species richness.We found that temperature was negatively correlated with the richness patterns of all and wide-ranged species,and that was the most important environmental factor,indicating a strong conservatism of its ancestral temperate niche.Habitat heterogeneity and long-term climate change were the best predictors of the spatial variation of narrow-ranged species richness.Overall,the combined model containing five predictors can explain ca.40%–50%of the variation in species richness.We further argued that additional evolutionary and biogeographical processes might have also played an essential role in shaping the Saxifraga diversity patterns and should be considered in future studies.展开更多
Aims Topography has long been recognized as an important factor in shaping species distributions.Many studies revealed that species may show species-habitat associations.However,few studies inves-tigate how species as...Aims Topography has long been recognized as an important factor in shaping species distributions.Many studies revealed that species may show species-habitat associations.However,few studies inves-tigate how species assemblages are associated with local habitats,and it still remains unclear how the community-habitat associa-tions vary with species abundance class and life stage.In this study,we analyzed the community-habitat associations in a subtropical montane forest.Methods The fully mapped 25-ha(500×500 m)forest plot is located in Badagongshan Nature Reserve in Hunan Province,Central China.It was divided into 625(20×20 m)quadrats.Habitat types were classified by multivariate regression tree analyses that cluster areas with similar species composition according to the topographic characteristics.Indicator species analysis was used to identify the most important species for structuring species assemblages.We also compared the community-habitat associations for two levels of species abundances(i.e.abundant and rare)and three different life stages(i.e.saplings,juveniles and adults),while accounting for sample size effects.Important Findings The Badagongshan plot was divided into five distinct habitat types,which explained 34.7%of the variance in tree species composi-tion.Even with sample size taken into account,community-habi-tat associations for rare species were much weaker than those for abundant species.Also when accounting for sample size,very small differences were found in the variance explained by topography for the three life stages.Indicator species of habitat types were mainly abundant species,and nearly all adult stage indicator species were also indicators in juvenile and sapling stages.Our study manifested that topographical habitat filtering was important in shaping over-all local species compositions.However,habitat filtering was not important in shaping rare species’distributions in this forest.The community-habitat association patterns in this forest were mainly shaped by abundant species.In addition,during the transitions from saplings to juveniles,and from juveniles to adults,the relative importance of habitat filtering was very weak.展开更多
Dear Editor,Grasses of the genus Panicumgrowin natural and agricultural ecosystems worldwide and include about 450 species distributed throughout tropical and temperate regions.Most Panicumgrasses remain unexploited,w...Dear Editor,Grasses of the genus Panicumgrowin natural and agricultural ecosystems worldwide and include about 450 species distributed throughout tropical and temperate regions.Most Panicumgrasses remain unexploited,with the exceptions of broomcorn millet(P.miliaceum)(Shi et al.,2019;Zou et al.,2019),switchgrass(P.virgatum)(Lovell et al.,2021),Hall’s panicgrass(P.hallii)(Lovell et al.,2018),and a few other species that have been successfully domesticated into staple,forage,and energy crops.Broomcorn millet(2n=4x=36)is probably one of the earliest domesticated grain crops,originating in North China around 10000 years ago.展开更多
基金Project supported by the Laboratory Open Fund of Beijing Smart-Chip Microelectronics Technology Co.,Ltdthe National Natural Science Foundation of China(Grant Nos.11690042 and 12035019)+1 种基金the National Major Scientific Research Instrument Projects(Grant No.61727804)the Natural Science Foundation of Shaanxi Province,China(Grant No.2022-JM-386)。
文摘Influences of off-state overdrive stress on the fluorine-plasma treated AlGaN/GaN high-electronic mobility transistors(HEMTs)are experimentally investigated.It is observed that the reverse leakage current between the gate and source decreases after the off-state stress,whereas the current between the gate and drain increases.By analyzing those changes of the reverse currents based on the Frenkel–Poole model,we realize that the ionization of fluorine ions occurs during the off-state stress.Furthermore,threshold voltage degradation is also observed after the off-state stress,but the degradations of AlGaN/GaN HEMTs treated with different F-plasma RF powers are different.By comparing the differences between those devices,we find that the F-ions incorporated in the GaN buffer layer play an important role in averting degradation.Lastly,suggestions to obtain a more stable fluorine-plasma treated AlGaN/GaN HEMT are put forwarded.
文摘This paper gives a definition of the Industrial Internet and expounds on the academic connotation of the future Industrial Internet.From this foundation,we outline the development and current status of the Industrial Internet in China and globally.Moreover,we detail the avant-garde paradigms encompassed within the National Natural Science Foundation of China(NSFC)’s“Future Industrial Internet Fundamental Theory and Key Technologies”research plan and its corresponding management strategies.This research initiative endeavors to enhance interdisciplinary collaborations,aiming for a synergistic alignment of industry,academia,research,and practical implementations.The primary focus of the research plan is on the pivotal scientific challenges inherent to the future industrial internet.It is poised to traverse the“first mile”,encompassing foundational research and pioneering innovations specific to the industrial internet,and seamlessly bridges to the“last mile”,ensuring the effective commercialization of scientific and technological breakthroughs into tangible industrial market applications.The anticipated contributions from this initiative are projected to solidify both the theoretical and practical scaffolding essential for the cultivation of a globally competitive industrial internet infrastructure in China.
基金supported by the National Natural Science Foundation of China(32125026,31988102)the National Key Research Development Program of China(2022YFF0802300)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31000000)。
文摘The Convention on Biological Diversity seeks to conserve at least 30%of global land and water areas by 2030,which is a challenge but also an opportunity to better preserve biodiversity,including flowering plants(angiosperms).Herein,we compiled a large database on distributions of over 300,000 angiosperm species and the key functional traits of 67,024 species.Using this database,we constructed biodiversity-environment models to predict global patterns of taxonomic,phylogenetic,and functional diversity in terrestrial angiosperms and provide a comprehensive mapping of the three diversity facets.We further evaluated the current protection status of the biodiversity centers of these diversity facets.Our results showed that geographical patterns of the three facets of plant diversity exhibited substantial spatial mismatches and nonoverlapping conservation priorities.Idiosyncratic centers of functional diversity,particularly of herbaceous species,were primarily distributed in temperate regions and under weaker protection compared with other biodiversity centers of taxonomic and phylogenetic facets.Our global assessment of multifaceted biodiversity patterns and centers highlights the insufficiency and unbalanced conservation among the three diversity facets and the two growth forms(woody vs.herbaceous),thus providing directions for guiding the future conservation of global plant diversity.
基金supported by the National Natural Science Foundation of China(32125026,31988102)the National Key Research Development Program of China(2022YFF0802300)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB31000000)。
文摘Global climate change has led to the decline of species and functional diversity in ecosystems,changing community composition and ecosystem functions.However,we still know little about how species with different resource-use strategies(different types of resource usage and plant growth of plants as indicated by the spectrum of plant economic traits,including acquisitive resource-use strategy and conservative resource-use strategy)would change in response to climate change,and how the changes in the diversity of species with different resource-use strategies may influence community-level productivity.Here,using long-term(1982–2017)observatory data in a temperate grassland in Inner Mongolia,we investigated how climate change had affected the species richness(SR)and functional richness(FRic)for the whole community and for species with different resource-use strategies.Specifically,based on data for four traits representing leaf economics spectrum(leaf carbon concentration,leaf nitrogen concentration,leaf phosphorus concentration,and specific leaf area),we divided 81 plant species appearing in the grassland community into three plant functional types representing resource-acquisitive,medium,and resource-conservative species.We then analyzed the changes in community-level productivity in response to the decline of SR and FRic at the community level and for different resource-use strategies.We found that community-level SR and FRic decreased with drying climate,which was largely driven by the decline of diversity for resource-acquisitive species.However,community-level productivity remained stable because resource-conservative species dominating this grassland were barely affected by climate change.Our study revealed distinctive responses of species with different resource-use strategies to climate change and provided a new approach based on species functional traits for predicting the magnitude and direction of climate change effects on ecosystem functions.
基金supported by Jiangxi Provincial Department of Education Science and Technology Research Project(GJJ2200433)the Natural Science Foundation of Jiangxi,China(#20224BAB213033)+2 种基金the National Key Research and Development Program of China(#2018YFA0606104)National Natural Science Foundation of China(#32125026,#31988102)the Strategic Priority Research Program of Chinese Academy of Sciences(#XDB31000000).
文摘Flowering phenology of plants,which is important for reproductive growth,has been shown to be influenced by climate change.Understanding how flowering phenology responds to climate change and exploring the variation of this response across plant groups can help predict structural and functional changes in plant communities in response to ongoing climate change.Here,we used long-term collections of 33 flowering plant species from the Gongga Mountains(Mt.Gongga hereafter),a biodiversity hotspot,to investigate how plant flowering phenology changed over the past 70 years in response to climate change.We found that mean flowering times in Mt.Gongga were delayed in all vegetation types and elevations over the last 70 years.Furthermore,flowering time was delayed more in lowlands than at high elevations.Interestingly,we observed that spring-flowering plants show earlier flowering times whereas summer/autumn plants show delayed flowering times.Non-synchronous flowering phenology across species was mainly driven by changes in temperature and precipitation.We also found that the flowering phenology of 78.8%plant species was delayed in response to warming temperatures.Our findings also indicate that the magnitude and direction of variation in plant flowering times vary significantly among species along elevation gradients.Shifts in flowering time might cause trophic mismatches with co-occurring and related species,affecting both forest ecosystem structure and function.
基金Key R&D project of Shandong Province,Grant/Award Number:2018GSF118152
文摘Background:Lung cancer is the most commonly diagnosed cancer worldwide.Its survival rate can be significantly improved by early screening.Biomarkers based on radiomics features have been found to provide important physiological information on tumors and considered as having the potential to be used in the early screening of lung cancer.In this study,we aim to establish a radiomics model and develop a tool to improve the discrimination between benign and malignant pulmonary nodules.Methods:A retrospective study was conducted on 875 patients with benign or malignant pulmonary nodules who underwent computed tomography(CT)examinations between June 2013 and June 2018.We assigned 612 patients to a training cohort and 263 patients to a validation cohort.Radiomics features were extracted from the CT images of each patient.Least absolute shrinkage and selection operator(LASSO)was used for radiomics feature selection and radiomics score calculation.Multivariate logistic regression analysis was used to develop a classification model and radiomics nomogram.Radiomics score and clinical variables were used to distinguish benign and malignant pulmonary nodules in logistic model.The performance of the radiomics nomogram was evaluated by the area under the curve(AUC),calibration curve and Hosmer-Lemeshow test in both the training and validation cohorts.Results:A radiomics score was built and consisted of 20 features selected by LASSO from 1288 radiomics features in the training cohort.The multivariate logistic model and radiomics nomogram were constructed using the radiomics score and patients’age.Good discrimination of benign and malignant pulmonary nodules was obtained from the training cohort(AUC,0.836;95%confidence interval[CI]:0.793-0.879)and validation cohort(AUC,0.809;95%CI:0.745-0.872).The Hosmer-Lemeshow test also showed good performance for the logistic regression model in the training cohort(P=0.765)and validation cohort(P=0.064).Good alignment with the calibration curve indicated the good performance of the nomogram.Conclusions:The established radiomics nomogram is a noninvasive preoperative prediction tool for malignant pulmonary nodule diagnosis.Validation revealed that this nomogram exhibited excellent discrimination and calibration capacities,suggesting its clinical utility in the early screening of lung cancer.
基金supported by the National Key Research Development Program of China(grant number 2018YFA0606104)National Natural Science Foundation of China(grant numbers 31988102,31911530102,and Chinese Academy of Sciences-Peking University Pioneer Collaboration Team.
文摘Aims Morphological variation of leaves is a key indicator of plant response to climatic change.Leaf size and shape are associated with carbon,water and energy exchange of plants with their environment.However,whether and how leaf size and shape responded to climate change over the past decades remains poorly studied.Moreover,many studies have only explored inter-but not intraspecific variation in leaf size and shape across space and time.Methods We collected>6000 herbarium specimens spanning 98 years(1910–2008)in China for seven representative dicot species and measured their leaf length and width.We explored geographical patterns and temporal trends in leaf size(i.e.leaf length,leaf width and length×width product)and shape(i.e.length/width ratio),and investigated the effects of changes in precipitation and temperature over time and space on the variation in leaf size and shape.Important Findings After accounting for the effects of sampling time,leaf size decreased with latitude for all species combined,but the relationship varied among species.Leaf size and shape were positively correlated with temperature and precipitation across space.After accounting for the effects of sampling locations,leaf size of all species combined increased with time.Leaf size changes over time were mostly positively correlated with precipitation,whereas leaf shape changes were mostly correlated with temperature.Overall,our results indicate significant spatial and temporal intraspecific variation in leaf size and shape in response to climate.Our study also demonstrates that herbarium specimens collected over a considerable period of time provide a good resource to study the impacts of climate change on plant morphological traits.
基金the Basic Public Welfare Research Project of Zhejiang Province(No.LGN20E050007,No.LGG19E050023)Xinjiang Boshiran Intelligent Agricultural Machinery Co.,Ltd.
文摘The fruit and vegetable picking has posed a great challenge on the production and markets during the harvest season.Manual picking cannot fully meet the rapid requirements of each market,mainly due to the high labor-intensive and time-consuming tasks,even the aging and shortage of agricultural labor force in recent years.Alternatively,smart robotics can be an efficient solution to increase the planting areas for the markets in combination with changes in cultivation,preservation,and processing technology.However,some improvements still need to be performed on these picking robots.To document the progress in and current status of this field,this study performed a bibliometric analysis.This analysis evaluated the current performance characteristics of various fruit and vegetable picking robots for better prospects in the future.Five perspectives were proposed covering the robotic arms,end effectors,vision systems,picking environments,and picking performance for the large-scale mechanized production of fruits and vegetables in modern agriculture.The current problems of fruit and vegetable picking robots were summarized.Finally,the outlook of the fruit and vegetable picking robots prospected from four aspects:structured environment for fruit planting,the algorithm of recognition and positioning,picking efficiency,and cost-saving picking robots.This study comprehensively assesses the current research status,thus helping researchers steer their projects or locate potential collaborators.
基金the National Natural Science Foundation of China(21676288,21773230)Dalian National Laboratory for Clean Energy(DNL)Cooperation Fund,CAS(DNL 180406)+1 种基金QIBEBT(QIBEBT ZZBS 201805)Liaoning Revitalization Talents Program(XLYC1807207)。
文摘Ce-or La-doped Cu/SSZ-13 catalysts were prepared by a hydrothermal method and Cu,Ce or La ions were incorporated through stepwise ion exchange,The catalyst activity was measured for the ammonia selective catalytic reduction reaction.The structure and composition of catalyst were characterized by using X-ray diffraction,scanning electron microscopy,inductively coupled plasma mass spectrometry solid-state NMR,NH_(3)-TPD techniques,and the active components were examined by XPS and XANES.The results indicate that the Ce and La doping can both completely preserve the SCR activity of Cu/SSZ-13 above 300℃,but there is also a decrease of activity below 200℃.On the other hand,Ce doping is beneficial to the formation of framework aluminum,stabilizes molecular sieve framework and Cu active sites of Cu/SSZ-13,thereby improves the catalyst hydrothermal stability.But La doping will decrease the amount of framework aluminum and Cu active sites of Cu/SSZ-13 after hydrothermally aging,even destroy zeolite CHA structure.This is quite harmful to the catalyst hydrothermal stability.
基金This work was partly funded by the National Key Research Development Program of China(#2017YFA0605101)National Natural Science Foundation of China(#31522012,#31470564,#31621091)Chinese Academy of Sciences-Peking University Pioneer Collaboration Team.Y.L.thanks for the support from Chinese Scholarship Council(CSC).X.X.thanks for the Fundamental Research Funds for the central Universities(YJ201721).
文摘Aims Plant height is a key functional trait related to aboveground bio-mass,leaf photosynthesis and plant fitness.However,large-scale geographical patterns in community-average plant height(cAPH)of woody species and drivers of these patterns across different life forms remain hotly debated.Moreover,whether cAPH could be used as a predictor of ecosystem primary productivity is unknown.Methods We compiled mature height and distributions of 11422 woody spe-cies in eastern Eurasia,and estimated geographic patterns in cAPH for different taxonomic groups and life forms.then we evaluated the effects of environmental(including current climate and historical climate change since the Last Glacial Maximum(LGM))and evolutionary factors on cAPH.Lastly,we compared the predictive power of cAPH on primary productivity with that of LiDAR-derived canopy-height data from a global survey.Important Findings Geographic patterns of cAPH and their drivers differed among taxonomic groups and life forms.the strongest predictor for cAPH of all woody species combined,angiosperms,all dicots and deciduous dicots was actual evapotranspiration,while temperature was the strongest pre-dictor for cAPH of monocots and tree,shrub and evergreen dicots,and water availability for gymnosperms.Historical climate change since the LGM had only weak effects on cAPH.No phylogenetic signal was detected in family-wise average height,which was also unrelated to the tested environmental factors.Finally,we found a strong correlation between cAPH and ecosystem primary productivity.Primary productivity showed a weaker relationship with cAPH of the tallest species within a grid cell and no relationship with LiDAR-derived canopy height reported in the global survey.Our findings suggest that current climate rather than historical climate change and evolutionary history determine the geographical patterns in cAPH.However,the relative effects of climatic factors representing environmental energy and water availability on spatial variations of cAPH vary among plant life forms.Moreover,our results also suggest that cAPH can be used as a good predictor of ecosystem primary productivity.
基金supported by the National Key R&D Program of China (2016YFB0401004)the National Natural Science Foundation of China (51625301, 51573059, 91233116)+1 种基金the National Basic Research Program of China (2015CB655003)Guangdong Provincial Department of Science and Technology (2016B090906003, 2016TX03C175)
文摘An organic compound exhibiting simultaneously reversible switch between its emission colors and luminescence mechanisms,possessing high contrast from deep blue normal fluorescence(NF) to yellow thermally activated delayed fluorescence(TADF),is reported. Based on these two complementary colors, white-light emission combining NF and TADF from a single compound can be achieved in various states. Experimental results and density functional theory calculations indicate that the controllable conformational distribution under thermal and mechanical activation is the mechanism responsible for the reversible switching behavior.
文摘The donor-n-conjugated-acceptor (D-n-A) structure is an important design for the luminescent materials be- cause of its diversity in the selections of donor, n-bridge and acceptor groups. Herein, we demonstrate two examples of D-^-A structures capable to finely modulate the excited state properties and arrangement of energy levels, TPA-AN-BP and CZP-AN-BP, which possess the same acceptor and n-bridge but different donor. The investigation of their photophysical properties and DFT calculation revealed that the D-n-A structure with proper donor, n-bridge and acceptor can result in separation of frontier molecular orbitals on the corresponding donor and acceptor with an obvious overlap on the n-bridge, resulting in a hybridized local and charge-transfer (HLCT) excited state with high photoluminescent (PL) efficiencies. Meanwhile, their singlet and triplet states are arranged on corresponding moie- ties with large energy gap between T2 and T1, and a small energy gap between S1 and T2, which favor the reverse intersystem crossing (RISC) from high-lying triplet levels to singlet levels. As a result, the sky-blue emission non-doped OLED based on the TPA-AN-BP reached maximum external quantum efficiency (EQE) of 4.39% and a high exciton utilization efficiency (EUE) of 77%. This study demonstrates a new strategy to construct highly effi- cient OLED materials.
基金supported by the National Natural Science Foundation of China(#31770566,#31770232)Biodiversity Survey,Observation and Assessment Program of Ministry of Ecology and Environment of China and the Fundamental Research Funds for the Central Universities of China(#SCU2021D006,#LZUJBKY202035)D.M.N.thanks Instituto Serrapilheira/Brazil(Serra-1912-32082)and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—CAPES/PrInt/Brazil(88887.474387/2020-00)for financial support during the time this research was carried out.
文摘The effects of contemporary climate,habitat heterogeneity and long-term climate change on species richness are well studied for woody plants in forest ecosystems,but poorly understood for herbaceous plants,especially in alpine–arctic ecosystems.Here,we aim to test if the previously proposed hypothesis based on the richness–environment relationship could explain the variation in richness patterns of the typical alpine–arctic herbaceous genus Saxifraga.Using a newly compiled distribution database of 437 Saxifraga species,we estimated the species richness patterns for all species,narrow-and wide-ranged species.We used generalized linear models and simultaneous autoregressive models to evaluate the effects of contemporary climate,habitat heterogeneity and historical climate on species richness patterns.Partial regressions were used to determine the independent and shared effects of different variables.Four widely used models were tested to identify their predictive power in explaining patterns of species richness.We found that temperature was negatively correlated with the richness patterns of all and wide-ranged species,and that was the most important environmental factor,indicating a strong conservatism of its ancestral temperate niche.Habitat heterogeneity and long-term climate change were the best predictors of the spatial variation of narrow-ranged species richness.Overall,the combined model containing five predictors can explain ca.40%–50%of the variation in species richness.We further argued that additional evolutionary and biogeographical processes might have also played an essential role in shaping the Saxifraga diversity patterns and should be considered in future studies.
基金National Natural Science Foundation of China(31270562,30900178,31200329 and 31500337)Key Laboratory of Aquatic Botany and Watershed Ecology,CAS(Y455432J02)the Chinese Forest Biodiversity Monitoring Network(29200931131101919).
文摘Aims Topography has long been recognized as an important factor in shaping species distributions.Many studies revealed that species may show species-habitat associations.However,few studies inves-tigate how species assemblages are associated with local habitats,and it still remains unclear how the community-habitat associa-tions vary with species abundance class and life stage.In this study,we analyzed the community-habitat associations in a subtropical montane forest.Methods The fully mapped 25-ha(500×500 m)forest plot is located in Badagongshan Nature Reserve in Hunan Province,Central China.It was divided into 625(20×20 m)quadrats.Habitat types were classified by multivariate regression tree analyses that cluster areas with similar species composition according to the topographic characteristics.Indicator species analysis was used to identify the most important species for structuring species assemblages.We also compared the community-habitat associations for two levels of species abundances(i.e.abundant and rare)and three different life stages(i.e.saplings,juveniles and adults),while accounting for sample size effects.Important Findings The Badagongshan plot was divided into five distinct habitat types,which explained 34.7%of the variance in tree species composi-tion.Even with sample size taken into account,community-habi-tat associations for rare species were much weaker than those for abundant species.Also when accounting for sample size,very small differences were found in the variance explained by topography for the three life stages.Indicator species of habitat types were mainly abundant species,and nearly all adult stage indicator species were also indicators in juvenile and sapling stages.Our study manifested that topographical habitat filtering was important in shaping over-all local species compositions.However,habitat filtering was not important in shaping rare species’distributions in this forest.The community-habitat association patterns in this forest were mainly shaped by abundant species.In addition,during the transitions from saplings to juveniles,and from juveniles to adults,the relative importance of habitat filtering was very weak.
基金supported by the National Natural Science Foundation of China(31901596)the Young Elite Scientists Sponsorship Program by CAST(2021QNRC001)to J.S.
文摘Dear Editor,Grasses of the genus Panicumgrowin natural and agricultural ecosystems worldwide and include about 450 species distributed throughout tropical and temperate regions.Most Panicumgrasses remain unexploited,with the exceptions of broomcorn millet(P.miliaceum)(Shi et al.,2019;Zou et al.,2019),switchgrass(P.virgatum)(Lovell et al.,2021),Hall’s panicgrass(P.hallii)(Lovell et al.,2018),and a few other species that have been successfully domesticated into staple,forage,and energy crops.Broomcorn millet(2n=4x=36)is probably one of the earliest domesticated grain crops,originating in North China around 10000 years ago.