The excited state characters of HY103 have been studied by means of time-resolved photon emission （time-correlated single photon counting） and time dependent density functional theory calculations. The experimental ...The excited state characters of HY103 have been studied by means of time-resolved photon emission （time-correlated single photon counting） and time dependent density functional theory calculations. The experimental and theoretical results demonstrate that HY103 dyes undergo an efficient one-bond-flip motion after photoexicitation at room temperature, which leads to a very short lifetime of the normM fluorescence state, and a weak fluorescence emission around 670 am. However, when HY103 are excited in amorphous glasses at 77 K, the normal fluorescence emission is prolonged to nanoseconds time scale about 2 ns, and the fluorescence emission is enhanced. Furthermore, a new emission state is produced, which is characterized as a volume-conserved twisted （VCT） state. This is the first observation of a VCT state. The experiment indicates that the VCT motion of excited state of π-conjugated molecules in restricted environment can form a stable emission state, and the excited state character of π-conjugated molecules in restricted environment is complex.展开更多
The current study explores how the ideological struggle is unfolded in the movie Forrest Gump （1994）. Through a critical examination of the text structure of the plot and the language used by four main characters, i...The current study explores how the ideological struggle is unfolded in the movie Forrest Gump （1994）. Through a critical examination of the text structure of the plot and the language used by four main characters, it demonstrates that conservatism has gained great victory over liberalism in the following way： Those with conservative values are highlighted repeatedly in a favorable way, while those who preach liberal values are frequently associated with tragic events, and ultimately, the latter all converted into conservatives in one way or another, which indicates a reconciliation between the two opposing ideologies. This study might shed light on how visual media can be geared towards political justifications, and bring audience to the level of conscious awareness of that effect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
Understanding large-scale patterns of biodiversity and their drivers remains central in ecology.Many hypotheses have been proposed,including hydrothermal dynamic hypothesis,tropical niche conservatism hypothesis,Janze...Understanding large-scale patterns of biodiversity and their drivers remains central in ecology.Many hypotheses have been proposed,including hydrothermal dynamic hypothesis,tropical niche conservatism hypothesis,Janzen’s hypothesis and a combination model containing energy,water,seasonality and habitat heterogeneity.Yet,their relative contributions to groups with different lifeforms and range sizes remain controversial,which have limited our ability to understand the general mechanisms underlying species richness patterns.Here we evaluated how lifeforms and species range sizes influenced the relative contributions of these three hypotheses to species richness patterns of a tropical family Moraceae.The distribution data of Moraceae species at a spatial resolution of 50 km×50 km and their lifeforms(i.e.shrubs,small trees and large trees)were compiled.The species richness patterns were estimated for the entire family,different life forms and species with different range sizes separately.The effects of environmental variables on species richness were analyzed,and relative contributions of different hypotheses were evaluated across life forms and species range size groups.The species richness patterns were consistent across different species groups and the species richness was the highest in Sichuan,Guangzhou and Hainan provinces,making these provinces the hotspots of this family.Climate seasonality is the primary factor in determining richness variation of Moraceae.The best combination model gave the largest explanatory power for Moraceae species richness across each group of range size and life forms followed by the hydrothermal dynamic hypothesis,Janzen’s hypothesis and tropical niche conservatism hypothesis.All these models has a large shared effects but a low independent effect(<5%),except rare species.These findings suggest unique patterns and mechanisms underlying rare species richness and provide a theoretical basis for protection of the Moraceae species in China.展开更多
Aims Biodiversity patterns along elevational gradients have been well documented.Yet,the variations of biodiversity patterns along elevations and their underlying mechanisms are still unclear.Integrating multiple face...Aims Biodiversity patterns along elevational gradients have been well documented.Yet,the variations of biodiversity patterns along elevations and their underlying mechanisms are still unclear.Integrating multiple facets of biodiversity provides novel insights into the mechanisms for driving community assembly.In this study,species abundance information was incorporated into taxonomic and phylogenetic diversity to reveal the ecological and evolutionary forces of plant community assembly along an elevational gradient in subtropical forests.Methods We selected 17 woody plant plots along an elevational gradient from 270 to 1470 m in eastern China’s subtropical forests.Both presence-based and abundance-based measures of angiosperm species were used to quantify taxonomic alpha diversity,phylogenetic alpha diversity,phylogenetic relatedness,as well as taxonomic and phylogenetic dissimilarity among these plots.And the relations between these measures and climatic and topographic variables were analyzed.Important Findings For both abundance-weighted and unweighted measures,we observed an overall increasing pattern for taxonomic alpha diversity along elevation,and distance-decay trends of taxonomic and phylogenetic similarity with increased elevational distances.However,there were disparity patterns of phylogenetic alpha diversity between abundance-weighted and unweighted measures.For phylogenetic structure,there was no significant trend along elevation.Both topographical and microclimatic variables were main drivers of diversity patterns and phylogenetic structure.Compared with unweighted measures,abundance-weighted measures were strongly related with the slope and stand basal area.Overall,our results prove that deterministic processes mediated by local species abundance imprint on plant community composition along the elevational gradient.展开更多
文摘The excited state characters of HY103 have been studied by means of time-resolved photon emission （time-correlated single photon counting） and time dependent density functional theory calculations. The experimental and theoretical results demonstrate that HY103 dyes undergo an efficient one-bond-flip motion after photoexicitation at room temperature, which leads to a very short lifetime of the normM fluorescence state, and a weak fluorescence emission around 670 am. However, when HY103 are excited in amorphous glasses at 77 K, the normal fluorescence emission is prolonged to nanoseconds time scale about 2 ns, and the fluorescence emission is enhanced. Furthermore, a new emission state is produced, which is characterized as a volume-conserved twisted （VCT） state. This is the first observation of a VCT state. The experiment indicates that the VCT motion of excited state of π-conjugated molecules in restricted environment can form a stable emission state, and the excited state character of π-conjugated molecules in restricted environment is complex.
文摘The current study explores how the ideological struggle is unfolded in the movie Forrest Gump （1994）. Through a critical examination of the text structure of the plot and the language used by four main characters, it demonstrates that conservatism has gained great victory over liberalism in the following way： Those with conservative values are highlighted repeatedly in a favorable way, while those who preach liberal values are frequently associated with tragic events, and ultimately, the latter all converted into conservatives in one way or another, which indicates a reconciliation between the two opposing ideologies. This study might shed light on how visual media can be geared towards political justifications, and bring audience to the level of conscious awareness of that effect
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Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31000000)National Key Research Development Program of China(2017YFA0605101,2017YFC0505203)National Natural Science Foundation of China(32C125026,31988102,31770566).
文摘Understanding large-scale patterns of biodiversity and their drivers remains central in ecology.Many hypotheses have been proposed,including hydrothermal dynamic hypothesis,tropical niche conservatism hypothesis,Janzen’s hypothesis and a combination model containing energy,water,seasonality and habitat heterogeneity.Yet,their relative contributions to groups with different lifeforms and range sizes remain controversial,which have limited our ability to understand the general mechanisms underlying species richness patterns.Here we evaluated how lifeforms and species range sizes influenced the relative contributions of these three hypotheses to species richness patterns of a tropical family Moraceae.The distribution data of Moraceae species at a spatial resolution of 50 km×50 km and their lifeforms(i.e.shrubs,small trees and large trees)were compiled.The species richness patterns were estimated for the entire family,different life forms and species with different range sizes separately.The effects of environmental variables on species richness were analyzed,and relative contributions of different hypotheses were evaluated across life forms and species range size groups.The species richness patterns were consistent across different species groups and the species richness was the highest in Sichuan,Guangzhou and Hainan provinces,making these provinces the hotspots of this family.Climate seasonality is the primary factor in determining richness variation of Moraceae.The best combination model gave the largest explanatory power for Moraceae species richness across each group of range size and life forms followed by the hydrothermal dynamic hypothesis,Janzen’s hypothesis and tropical niche conservatism hypothesis.All these models has a large shared effects but a low independent effect(<5%),except rare species.These findings suggest unique patterns and mechanisms underlying rare species richness and provide a theoretical basis for protection of the Moraceae species in China.
基金This work was supported by the National Natural Science Foundation of China(32071538 to J.Z.and 31600343 to K.S.)Shanghai Natural Science Foundation(20ZR1418100 to J.Z.)East China Normal University to J.Z.and Z.Z.
文摘Aims Biodiversity patterns along elevational gradients have been well documented.Yet,the variations of biodiversity patterns along elevations and their underlying mechanisms are still unclear.Integrating multiple facets of biodiversity provides novel insights into the mechanisms for driving community assembly.In this study,species abundance information was incorporated into taxonomic and phylogenetic diversity to reveal the ecological and evolutionary forces of plant community assembly along an elevational gradient in subtropical forests.Methods We selected 17 woody plant plots along an elevational gradient from 270 to 1470 m in eastern China’s subtropical forests.Both presence-based and abundance-based measures of angiosperm species were used to quantify taxonomic alpha diversity,phylogenetic alpha diversity,phylogenetic relatedness,as well as taxonomic and phylogenetic dissimilarity among these plots.And the relations between these measures and climatic and topographic variables were analyzed.Important Findings For both abundance-weighted and unweighted measures,we observed an overall increasing pattern for taxonomic alpha diversity along elevation,and distance-decay trends of taxonomic and phylogenetic similarity with increased elevational distances.However,there were disparity patterns of phylogenetic alpha diversity between abundance-weighted and unweighted measures.For phylogenetic structure,there was no significant trend along elevation.Both topographical and microclimatic variables were main drivers of diversity patterns and phylogenetic structure.Compared with unweighted measures,abundance-weighted measures were strongly related with the slope and stand basal area.Overall,our results prove that deterministic processes mediated by local species abundance imprint on plant community composition along the elevational gradient.
