Soil water is an important factor restricting afforestation on the semi-arid Loess Plateau.The microtopography of the loess slope has changed the distribution pattern of soil water on the slope.To improve water utiliz...Soil water is an important factor restricting afforestation on the semi-arid Loess Plateau.The microtopography of the loess slope has changed the distribution pattern of soil water on the slope.To improve water utilization efficiency and optimize afforestation configuration patterns,the relationship between soil water and precipitation at micro-topographic scale must be studied.We used time series analysis to study the temporal variation of soil water and its response to precipitation in four kinds of micro-topographies and undisturbed slope on loess slopes.Micro-topographies significantly influenced soil water distribution and dynamics on the slopes.Soil water stored in the platform,sinkhole,and ephemeral gully influenced subsequent soil water for 4 weeks,whereas soil water stored in the scarp and undisturbed slope could influence soil water for 2 weeks.It took 12 weeks,10 weeks,18 weeks,6 weeks,and 12 weeks for precipitation to reach the deeper soil layer in the platform,sinkhole,scarp,ephemeral gully,and undisturbed slope,respectively.These soil water characteristics in different micro-topographies are vital factors that should be taken into consideration when undertaking afforestation on the Loess Plateau.展开更多
Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and speci...Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and species interactions in forest systems.In this study,spatial point pattern analysis investigated the combined eff ects of intraspecifi c interactions and environmental heterogeneity on the spatial structure and internal maintenance mechanisms of Picea crassifolia in the Qilian Mountain National Nature Reserve,China.Data were obtained from a 10.2-ha dynamic monitoring plot(DMP)and sixteen 0.04-ha elevation gradient plots(EGPs).Under complete spatial randomness,both mature trees and saplings in the DMP demonstratedlarge-scale aggregation with negative correlations.In EGPs,saplings were clustered in small mesoscales,mature trees were randomly distributed,and the interactions of saplingstrees at all elevations were not correlated.By eliminating the interference of environmental heterogeneity through the inhomogeneous Poisson process,saplings in the DMP and EGPs were clustered in small scales and trees randomly distributed.Intraspecifi c associations were negatively correlated,in the DMP and at low elevations,and no correlations in high elevations of EGPs.In the vertical scale,saplings showed a small-scale aggregation pattern with increase in elevation,and the aggregation degree fi rst decreased and then increased.The interactions of saplings-trees and saplings–saplings showed inhibitions at small scales,with the degree of inhibition gradually decreasing.Spatial patterns and associations of adults–adults did not change signifi-cantly.The results revealed that intraspecifi c interactions and environmental heterogeneity regulated the spatial patterns of P.crassifolia at small and large scales,respectively.Environmental heterogeneity might be the most decisive factor aff ecting the spatial patterns of saplings,while trees were more aff ected by intraspecifi c interactions.Moreover,competition between trees in this area could be more common than facilitation for the growth and development of individuals.展开更多
Microtopography may affect the distribution of forests through its effect on rain redistribution and soil water distribution on the semi-arid Loess Plateau,China.In this study,we investigated the characteristics of mi...Microtopography may affect the distribution of forests through its effect on rain redistribution and soil water distribution on the semi-arid Loess Plateau,China.In this study,we investigated the characteristics of microtopography on two shady slopes（slope A,5 hm2,uniform slope;slope B,5 hm2,microtopography slope） and surveyed the height,the diameter at breast height and the location（x,y coordinates） of all selected individual trees（Robinia pseudoacacia Linn.,Pyrus betulifolia Bunge,Populus hopeiensis Hu ＆ Chow,Armeniaca sibirica Lam.,Populus simonii Carr.and Ulmus pumila Linn.） on slope A and slope B in the watersheds of Wuqi county,Shaanxi province.Subsequently,the effects of microtopography on the spatial pattern of forest stands were analyzed using Ripley＇s K（r） function.The results showed that：（1） The maximal aggregation radiuses of the tree species on the uniform slope（slope A） were larger than 40 m,whereas those of the tree species on the microtopography slope（slope B） were smaller than 30 m.（2） On slope B,the spatial association of R.pseudoacacia with P.betulifolia,A.sibirica,P.simonii and U.pumila varied from being strongly negative to positive at microtopography scales.The spatial association of Populus hopeiensis Hu ＆ Chow with U.pumila also varied from being strongly negative to positive at microtopography scales.However,there was no spatial association between P.betulifolia and P.hopeiensis,P.betulifolia and A.sibirica,P.betulifolia and P.simonii,P.betulifolia and U.pumila,P.hopeiensis and A.sibirica,P.hopeiensis and P.simonii,A.sibirica and P.simonii,A.sibirica and U.pumila,and P.simonii and U.pumila.On slope A,the spatial association between tree species were strongly negative.The results suggest that microtopography may shape tree distribution patterns on the semi-arid Loess Plateau.展开更多
Forest tourist areas have an excellent ecological environment,which is conducive to people's physical and mental health.In this study,Fuzhou National Forest Park and Wuying National Forest Park were selected as ty...Forest tourist areas have an excellent ecological environment,which is conducive to people's physical and mental health.In this study,Fuzhou National Forest Park and Wuying National Forest Park were selected as typical representatives of the southern and northern forest parks,respectively,which were compared by qualitative and quantitative research methods from such five aspects as air quality,climate quality,water environment quality,acoustic environment quality and biological population in some forest areas.The results showed that Fuzhou National Forest Park has a concentration of negative oxygen ions much higher than Wuying National Forest Park,and is thus more conducive to people's health;and it has the characteristics of warm and comfortable climate throughout the year and high biodiversity,but the noise is 4.35 db higher than Wuying National Forest Park,and the water quality is slightly poorer than that of Wuying National Forest Park.And its DO value is about 3.89 smaller in autumn than in summer.In Wuying National Forest Park,the concentration of negative oxygen ions is 53.6% lower than Fuzhou National Forest Park,but it is also above the national standard.The climate is only comfortable in June-August,and is colder or cooler in other months.The water quality is better than that of Fuzhou National Forest Park.In particular,the PH value is about 0.38 lower than that of Fuzhou National Forest Park.It has its own unique biological characteristics.The number of tourists in summer is higher,resulting in higher noise in summer than in autumn.The two forest parks in the north and the south are both good places for people to relax and enjoy.展开更多
Spatial heterogeneity is an inherent characteristic of natural forest landscapes, therefore estimation of structural variability, including the collection and analyzing of field measurements, is a growing challenge fo...Spatial heterogeneity is an inherent characteristic of natural forest landscapes, therefore estimation of structural variability, including the collection and analyzing of field measurements, is a growing challenge for monitoring wildlife habitat di- versity and ecosystem sustainability. In this study, we investigated the combined influence of plot shape and size on the accuracy of assessment of conventional and rare structural features in two young-growth spruce-dominated forests in northwestern China. We used a series of inventory schemes and analytical approaches. Our data showed that options for sampling protocols, especially the selection of plot size considered in structural attributes measurement, dramatically af- fect the minimum number of plots required to meet a certain accuracy criteria. The degree of influence of plot shape is related to survey objectives; thus, effects of plot shape differ for evaluations of the ＂mean＂ or ＂representative＂ stand structural conditions from that for the range of habitat （in extreme values）. Results of Monte Carlo simulations suggested that plot sizes 〈0.1 ha could be the most efficient way to sample for conventional characteristics （features with relative constancy within a site, such as stem density）. Also, 0.25 ha or even larger plots may have a greater likelihood of capturing rare structural attributes （features possessing high randomness and spatial heterogeneity, such as volume of coarse woody debris） in our forest type. These findings have important implications for advisable sampling protocol （plot size and shape） to adequately capture information on forest habitat structure and diversity; such efforts must be based on a clear definition of which types are structural attributes to measure.展开更多
Drought is one of the major meteorological disasters affecting the climate in China.In this paper,the interannual variation and seasonal distribution changes of drought at different time scales were analyzed with the ...Drought is one of the major meteorological disasters affecting the climate in China.In this paper,the interannual variation and seasonal distribution changes of drought at different time scales were analyzed with the standardized precipitation index( SPI) as the drought evaluation criterion to the precipitation data of the 5 meteorological stations of Jinan,Tai'an,Yiyuan,Shen County and Yanzhou from 1960 to 2013.The results showed that:(1) the frequency of drought was low in spring and summer in inland areas of Shandong Province,while autumn had frequent occurrences of moderate drought,and winter had frequent occurrences of heavy and severe droughts.(2) In the 1960 s,1980 s and early 21^(st) century,the number of droughts increased significantly,and the SPI values showed a significant decrease.(3) The 3-month time scale range was wide,during which the frequency of occurrence was high.The trend of SPI changes at the 12-month time scale was affected by the accumulation of antecedent precipitation,and the change was slow.The research results can provide a scientific reference for arid climate analysis and water resources management in agriculture and production in inland areas of Shandong Province.展开更多
Air pollution has become the most concerned regional environmental problem in China at present.According to the data of typical cities in Shandong Province from January,2014 to December,2015,the air quality status,pol...Air pollution has become the most concerned regional environmental problem in China at present.According to the data of typical cities in Shandong Province from January,2014 to December,2015,the air quality status,pollution status and spatial variation characteristics of air pollutants were classified and analyzed,thereby providing a scientific basis for air pollution control.The conclusions of this study are as follows:(1) PM_(2.5) was the most important atmospheric pollutant in Shandong Province;(2) Qingdao had the best air quality with a good air quality rate of 73.7%,while Jinan had the worst air quality with a good air quality rate only of 31.3%; and(3) the days with heavy pollution were mainly concentrated in winter,mainly due to coal-fired heating in winter.展开更多
[Objectives] To analyze and study the characteristics of rural labor flow to the tourism industry in Taian City of Shandong Province,and propose some measures for solving the problems of labor support in the developme...[Objectives] To analyze and study the characteristics of rural labor flow to the tourism industry in Taian City of Shandong Province,and propose some measures for solving the problems of labor support in the development of rural tourism in Taian City. [Methods]The indicators were analyzed using the time series based on the relevant data on the labor employment and flow of rural households in Taian City in2005-2013. [Results] In Taian City,the number of rural laborers engaged in the primary industry decreased at the rate of 96 people/year,while the number of laborers engaged in the secondary and tertiary industries increased at the rate of 29 people/year and 3 people/year,respectively. The proportion of the three traditional tourism elements of transportation,lodging and catering in the tourism industry has been fluctuating,and the minimum was not lower than 30%. The recreational category was decreasing year by year,and only accounted for 1.7% in 2010.In summary,in the development of rural tourism in Taian City,the labor flow has problems such as low rural social security,weak attraction to young people,and large psychological barriers to returning to the hometown for employment. [Conclusions] In view of the problems,it is recommended to implement the rural revitalization strategy,attach importance to regional labor competition,give full play to the advantages of tourist cities,highlight product characteristics,increase cultural added value and improve the quality of operators to develop rural tourism. This study is intended to provide a scientific reference for talent support for rural revitalization in Taian City.展开更多
[Objectives]To evaluate the effectiveness of Rain Classroom intelligent teaching in the course of Spring Water Tourism Resources.[Methods]The course of Spring Water Tourism Resources in the course of Overview of Touri...[Objectives]To evaluate the effectiveness of Rain Classroom intelligent teaching in the course of Spring Water Tourism Resources.[Methods]The course of Spring Water Tourism Resources in the course of Overview of Tourism Resources was taken as an example,the pre-class preparation,in-class teaching,and after-class evaluation links were designed separately through the Rain Classroom platform.Then,a questionnaire survey was carried out for the students of Spring Water Tourism Resources.[Results]About 58.3%of the students believed that the greatest advantage of using the Rain Classroom teaching platform is that the learning method is flexible and can improve the ability of independent learning;61.78%of students stated that playing 3D animation in the classroom has the best effect for learning different tourism resources;with the aid of the Rain Classroom platform,the communication between teachers and students becomes more timely,and the students' ability to deal with practical problems can be practiced.[Conclusions]This study is intended to build an intelligent classroom model suitable for tourism management department based on the Rain Classroom platform.It is recommended to promote and apply this model in the teaching of tourism management.展开更多
Taking the knowledge points of hotel construction site selection as an example,this paper integrated the information-based teaching method with traditional classrooms.With the aid of virtual reality(VR)technology,the ...Taking the knowledge points of hotel construction site selection as an example,this paper integrated the information-based teaching method with traditional classrooms.With the aid of virtual reality(VR)technology,the information-based teaching can turn the abstract knowledge into vivid knowledge.Using the Rain Classroom platform,teachers can communicate with students in a better manner.Combined with the powerful spatial data analysis function of geographic information system(GIS)software,it is intended to provide new ideas and perspectives for the effective integration of traditional teaching classrooms and information technology,and effectively apply them to the practical teaching process.展开更多
This paper selects Qingdao Textile Valley as the research object,establishes the evaluation system of industrial heritage tourism resources,and analyzes the evaluation factors of industrial heritage tourism resources,...This paper selects Qingdao Textile Valley as the research object,establishes the evaluation system of industrial heritage tourism resources,and analyzes the evaluation factors of industrial heritage tourism resources,such as resource element value,market location value,and environmental factors.Then this paper puts forward some effective suggestions to promote the development of industrial heritage tourism in Textile Valley.The results show that the measures put forward,such as fully tapping the value of resource elements,improving the surrounding traffic environment,perfecting tourism signs,perfecting local traffic routes,improving the complementarity of tourism resources,and expanding the tourist market,can scientifically and effectively protect urban industrial heritage,improve the development level of urban tourism,and speed up the transformation of new and old energy in Qingdao.展开更多
The electrical properties of high-entropy ceramics(HECs)have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy engineering...The electrical properties of high-entropy ceramics(HECs)have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy engineering.Novel high-entropy(Sm_(0.2)Eu_(0.2)Gd_(0.2)Ho_(0.2)Yb_(0.2))CrO_(3)(HE-RECrO_(3))nanofibers were prepared by electro spinning.This work demonstrates that HE-RECrO_(3)nanofibe rs were successfully synthesized at a low temperature(800℃),which is approximately 400℃lower than the temperatures at which chromate ceramics were synthesized via the sol-gel method and the solid-state reaction method.The resistivity of HE-RECrO_(3)nanofibers decreases exponentially with increasing temperature from 25 to600℃.The logarithm of the resistivity is linearly related to the inverse of the temperature,confirming the negative temperature coefficient property of HE-RECrO_(3)nanofibers.The B_(25/50)value of the HERECrO_(3)nanofibers reaches 4072 K.In conclusion,HE-RECrO_(3)nanofibers are expected to be potential candidates for negative-temperature-coefficient(NTC)thermistors.展开更多
The development of solid-state smart materials, in particular those showing photoresponsive luminescence, is highly desirable for their cutting edge applications in displays, sensors, data-storage, and anticounterfeit...The development of solid-state smart materials, in particular those showing photoresponsive luminescence, is highly desirable for their cutting edge applications in displays, sensors, data-storage, and anticounterfeiting. However, to achieve both excellent photoresponsive performance and bright luminescence in solid state remains challenge. Herein, we integrate a novel photochromic fluorophore YL into flexible polymer chains, thereby enabling the resultant polymer PYL with reversible photoisomerization upon aggregation. Remarkably, the polymer PYL possesses excellent photochromic properties and aggregationinduced emission(AIE) activity, which can be attributed to the photoactive YL moiety. Upon light exposure, its film exhibits reversibly off-to-on fluorescent modulation with quick response, high emission efficiency and signal contrast, sharply different from the weak emission in solution. The novel photoresponsive AIE polymer with invisible/visible color and fluorescence transformation allows for advanced anti-counterfeiting applications. This work provides an efficient platform for constructing solid-state photocontrollable luminescent materials.展开更多
Uniting dual-modality of fluorescence and photoacoustic(PA)imaging into theranostic nanoprobes is imperative for spatiotemporally tracking of drug delivery,distribution,and release.Herein,we present a rational design ...Uniting dual-modality of fluorescence and photoacoustic(PA)imaging into theranostic nanoprobes is imperative for spatiotemporally tracking of drug delivery,distribution,and release.Herein,we present a rational design strategy of molecularly precise amphiphilic prodrugs BP_(n)-Cy-S-CPT(n=0,5,and 20,refers to the degree of polyethylene glycol(PEG)polymerization;CPT=camptothecin)to tune their self-assembly behaviour,innovatively integrating dual-modal PA and near-infrared(NIR)fluorescence imaging in a single-molecular framework.Among these elaborately designed prodrugs,it is found that only BP_(20)-Cy-S-CPT could form uniform and highly stable self-assemblies,especially in showing synergistically enhanced PA and dualchannel NIR signals.In detail,PA signal is employed to trace the in vivo delivery with high spatial resolution,meanwhile the glutathione(GSH)-triggered dual-channel fluorescence response could real-timely monitor drug distribution and release without"blind spot".The results of in vivo dual-modal PA/NIR imaging have verified that BP_(20)-Cy-S-CPT displayed synergistic targeting(including passive,active,and activatable targeting)for tumor-specific delivery,and thereby executed CPT release in the tumor site.Consequently,our molecularly precise BP_(20)-Cy-S-CPT self-assemblies could make a breakthrough to spatiotemporally track the in vivo drug release profile,expanding the intelligent theranostic toolbox for precise cancer treatment.展开更多
Image guided photodynamic therapy(PDT)combines fluorescence tracing and phototherapy,which can achieve a more accurate and effective treatment effect.However,traditional photosensitizers are limited by the aggregation...Image guided photodynamic therapy(PDT)combines fluorescence tracing and phototherapy,which can achieve a more accurate and effective treatment effect.However,traditional photosensitizers are limited by the aggregation-caused fluorescence quenching(ACQ)effect and low reactive oxygen species(ROS)generation in a hypoxic environment,resulting in poor imaging and treatment effect.Herein,we report a tricyano-methylene-pyridine(TCM)-based Type I aggregation-induced emission(AIE)photosensitizer(TCM-MBP),the strong elec-tron acceptance(D-A)effect extends the wavelength to near-infrared(NIR)region to reduce the autofluorescence interference,and oxygen atoms provide lone pair electrons to enhance the inter system crossing(ISC)rate,thereby promoting the generation of more triplet states to produce ROS.The AIE photosensitizer TCM-MBP exhibited low oxygen dependence,NIR emission,and higher ROS production compared to commercially avail-able Ce_(6) and RB.After encapsulation with DSPE-PEG 2000,TCM-MBP nanoparticles(TCM-MBP NPs)could penetrate to visualize cells and efficiently kill cancer cells upon light irradiation.This study provides an oxygen-independent AIE photosensitizer,which has great potential to replace the commercial ACQ photosensitizers.展开更多
Dear Editor,Growing evidence has indicated that heterologous COVID-19 vaccination could generate higher antibody(Ab)and cellmediated immune(CMI)responses than homologous vaccination regimen.1–3 However,fundamental un...Dear Editor,Growing evidence has indicated that heterologous COVID-19 vaccination could generate higher antibody(Ab)and cellmediated immune(CMI)responses than homologous vaccination regimen.1–3 However,fundamental understanding of immunological mechanisms dictating the enhanced vaccine immunity is still lacking.To gain mechanistic insights,we comprehensively profiled the immune responses generated by homologous or heterologous booster vaccination in mice(Fig.1a).展开更多
High-fidelity spatiotemporal monitoring of the cell membrane is critically important.However,commercial fluorescence probes are stalked by the aggregation-caused quenching(ACQ)effect,and the reported aggregation-induc...High-fidelity spatiotemporal monitoring of the cell membrane is critically important.However,commercial fluorescence probes are stalked by the aggregation-caused quenching(ACQ)effect,and the reported aggregation-induced emission(AIE)-active probes are always limited by nonspecific aggregations in the biological environment.Herein,we report the rational molecular design of a stateof-the-art amphiphilic AIE luminogen(AIEgen),membrane tracker QMC12,using a core quinolinemalononitrile(QM)structure to suppress the ACQ effect,incorporate a positively charged pyridinium to regulate dispersity and strengthen the binding affinity to the negatively charged cell membrane,and extend the alky chain to improve the anchoring ability to the cell membrane.The membrane tracker QMC12,which disperses well in both hydrophilic and lipophilic environments,not only achieves minimal background interference and high signal-to-noise(S/N)ratio in the“ultrafast”visualization of the cell membrane,but also endows a“wash-free”characteristic.Furthermore,it realizes a spatial three dimensional(3D)view in a multicellular spheroid model and morphology changes over time.Moreover,QMC12 avoids false staining and signal loss and unprecedentedly achieves the direct observation of the cell membrane’s microstructure,which could elucidate spatiotemporal 3D model studies of the intercellular information exchange.展开更多
Kasha’s rule,which states that all exciton emissions occur from the lowest excited state and are independent of excitation energy,makes high-energy excitons difficult to use and severely hinders the widespread applic...Kasha’s rule,which states that all exciton emissions occur from the lowest excited state and are independent of excitation energy,makes high-energy excitons difficult to use and severely hinders the widespread applications of organic photoluminescent materials in the real world.For decades,scientists have tried to break this rule to unleash the power of high-energy excitons,but only minimal progress has been achieved,with no rational guiding principles provided,and few applications developed.So far,breaking Kasha’s rule has remained a purely academic concept.In this paper,we introduce a design principle for a purely organic anti-Kasha system and synthesise a series of compounds based on the design rule.As predicted,these compounds all display evident S_(2) emissions in dilute solutions.In addition,we introduce a highly accurate(over 90%)convolutional neural network as an assistant for the classification of cells using anti-Kasha luminogens,thereby providing a new application direction for anti-Kasha systems.展开更多
基金financially supported by Forestry Industry Research Special Funds for Public Welfare Projects(201104002-2)China National Scientific and Technical Innovation Research Project for 12th Five Year Plan(2015BAD07B0201)
文摘Soil water is an important factor restricting afforestation on the semi-arid Loess Plateau.The microtopography of the loess slope has changed the distribution pattern of soil water on the slope.To improve water utilization efficiency and optimize afforestation configuration patterns,the relationship between soil water and precipitation at micro-topographic scale must be studied.We used time series analysis to study the temporal variation of soil water and its response to precipitation in four kinds of micro-topographies and undisturbed slope on loess slopes.Micro-topographies significantly influenced soil water distribution and dynamics on the slopes.Soil water stored in the platform,sinkhole,and ephemeral gully influenced subsequent soil water for 4 weeks,whereas soil water stored in the scarp and undisturbed slope could influence soil water for 2 weeks.It took 12 weeks,10 weeks,18 weeks,6 weeks,and 12 weeks for precipitation to reach the deeper soil layer in the platform,sinkhole,scarp,ephemeral gully,and undisturbed slope,respectively.These soil water characteristics in different micro-topographies are vital factors that should be taken into consideration when undertaking afforestation on the Loess Plateau.
基金supported by the National Natural Science Foundation of China(No.32060247)the Central Guidance on Local Science and Technology Development Fund of Gansu Province(No.22ZY2QG001).
文摘Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and species interactions in forest systems.In this study,spatial point pattern analysis investigated the combined eff ects of intraspecifi c interactions and environmental heterogeneity on the spatial structure and internal maintenance mechanisms of Picea crassifolia in the Qilian Mountain National Nature Reserve,China.Data were obtained from a 10.2-ha dynamic monitoring plot(DMP)and sixteen 0.04-ha elevation gradient plots(EGPs).Under complete spatial randomness,both mature trees and saplings in the DMP demonstratedlarge-scale aggregation with negative correlations.In EGPs,saplings were clustered in small mesoscales,mature trees were randomly distributed,and the interactions of saplingstrees at all elevations were not correlated.By eliminating the interference of environmental heterogeneity through the inhomogeneous Poisson process,saplings in the DMP and EGPs were clustered in small scales and trees randomly distributed.Intraspecifi c associations were negatively correlated,in the DMP and at low elevations,and no correlations in high elevations of EGPs.In the vertical scale,saplings showed a small-scale aggregation pattern with increase in elevation,and the aggregation degree fi rst decreased and then increased.The interactions of saplings-trees and saplings–saplings showed inhibitions at small scales,with the degree of inhibition gradually decreasing.Spatial patterns and associations of adults–adults did not change signifi-cantly.The results revealed that intraspecifi c interactions and environmental heterogeneity regulated the spatial patterns of P.crassifolia at small and large scales,respectively.Environmental heterogeneity might be the most decisive factor aff ecting the spatial patterns of saplings,while trees were more aff ected by intraspecifi c interactions.Moreover,competition between trees in this area could be more common than facilitation for the growth and development of individuals.
基金financially supported by China National Scientific and Technical Innovation Research Project for 12~(th) Five Year Plan (2011BAD38B0601)the National Natural Science Foundation of China (41472313)the Natural Science Foundation of Shandong Province (ZR2011DM012,ZR2014DL002)
文摘Microtopography may affect the distribution of forests through its effect on rain redistribution and soil water distribution on the semi-arid Loess Plateau,China.In this study,we investigated the characteristics of microtopography on two shady slopes（slope A,5 hm2,uniform slope;slope B,5 hm2,microtopography slope） and surveyed the height,the diameter at breast height and the location（x,y coordinates） of all selected individual trees（Robinia pseudoacacia Linn.,Pyrus betulifolia Bunge,Populus hopeiensis Hu ＆ Chow,Armeniaca sibirica Lam.,Populus simonii Carr.and Ulmus pumila Linn.） on slope A and slope B in the watersheds of Wuqi county,Shaanxi province.Subsequently,the effects of microtopography on the spatial pattern of forest stands were analyzed using Ripley＇s K（r） function.The results showed that：（1） The maximal aggregation radiuses of the tree species on the uniform slope（slope A） were larger than 40 m,whereas those of the tree species on the microtopography slope（slope B） were smaller than 30 m.（2） On slope B,the spatial association of R.pseudoacacia with P.betulifolia,A.sibirica,P.simonii and U.pumila varied from being strongly negative to positive at microtopography scales.The spatial association of Populus hopeiensis Hu ＆ Chow with U.pumila also varied from being strongly negative to positive at microtopography scales.However,there was no spatial association between P.betulifolia and P.hopeiensis,P.betulifolia and A.sibirica,P.betulifolia and P.simonii,P.betulifolia and U.pumila,P.hopeiensis and A.sibirica,P.hopeiensis and P.simonii,A.sibirica and P.simonii,A.sibirica and U.pumila,and P.simonii and U.pumila.On slope A,the spatial association between tree species were strongly negative.The results suggest that microtopography may shape tree distribution patterns on the semi-arid Loess Plateau.
基金Supported by National Natural Science Foundation of China(41907050)Natural Science Foundation of Shandong Province(ZR2019MD031)Scientific Research Projects in Colleges and Universities in Shandong Province(J18KA197)
文摘Forest tourist areas have an excellent ecological environment,which is conducive to people's physical and mental health.In this study,Fuzhou National Forest Park and Wuying National Forest Park were selected as typical representatives of the southern and northern forest parks,respectively,which were compared by qualitative and quantitative research methods from such five aspects as air quality,climate quality,water environment quality,acoustic environment quality and biological population in some forest areas.The results showed that Fuzhou National Forest Park has a concentration of negative oxygen ions much higher than Wuying National Forest Park,and is thus more conducive to people's health;and it has the characteristics of warm and comfortable climate throughout the year and high biodiversity,but the noise is 4.35 db higher than Wuying National Forest Park,and the water quality is slightly poorer than that of Wuying National Forest Park.And its DO value is about 3.89 smaller in autumn than in summer.In Wuying National Forest Park,the concentration of negative oxygen ions is 53.6% lower than Fuzhou National Forest Park,but it is also above the national standard.The climate is only comfortable in June-August,and is colder or cooler in other months.The water quality is better than that of Fuzhou National Forest Park.In particular,the PH value is about 0.38 lower than that of Fuzhou National Forest Park.It has its own unique biological characteristics.The number of tourists in summer is higher,resulting in higher noise in summer than in autumn.The two forest parks in the north and the south are both good places for people to relax and enjoy.
基金supported by the Hundred Talents Program of the Chinese Academy of Sciences(No.29Y127D11)the National Natural Science Foundation of China(No.41271524)+1 种基金Natural Science Foundation of Gansu Province(No.1210RJDA015)Forestry Industry Research Special Funds for Public Welfare Projects(No.201104009-08)
文摘Spatial heterogeneity is an inherent characteristic of natural forest landscapes, therefore estimation of structural variability, including the collection and analyzing of field measurements, is a growing challenge for monitoring wildlife habitat di- versity and ecosystem sustainability. In this study, we investigated the combined influence of plot shape and size on the accuracy of assessment of conventional and rare structural features in two young-growth spruce-dominated forests in northwestern China. We used a series of inventory schemes and analytical approaches. Our data showed that options for sampling protocols, especially the selection of plot size considered in structural attributes measurement, dramatically af- fect the minimum number of plots required to meet a certain accuracy criteria. The degree of influence of plot shape is related to survey objectives; thus, effects of plot shape differ for evaluations of the ＂mean＂ or ＂representative＂ stand structural conditions from that for the range of habitat （in extreme values）. Results of Monte Carlo simulations suggested that plot sizes 〈0.1 ha could be the most efficient way to sample for conventional characteristics （features with relative constancy within a site, such as stem density）. Also, 0.25 ha or even larger plots may have a greater likelihood of capturing rare structural attributes （features possessing high randomness and spatial heterogeneity, such as volume of coarse woody debris） in our forest type. These findings have important implications for advisable sampling protocol （plot size and shape） to adequately capture information on forest habitat structure and diversity; such efforts must be based on a clear definition of which types are structural attributes to measure.
基金Supported by Colleges and universities scientific research project of Shandong(J18KA197)
文摘Drought is one of the major meteorological disasters affecting the climate in China.In this paper,the interannual variation and seasonal distribution changes of drought at different time scales were analyzed with the standardized precipitation index( SPI) as the drought evaluation criterion to the precipitation data of the 5 meteorological stations of Jinan,Tai'an,Yiyuan,Shen County and Yanzhou from 1960 to 2013.The results showed that:(1) the frequency of drought was low in spring and summer in inland areas of Shandong Province,while autumn had frequent occurrences of moderate drought,and winter had frequent occurrences of heavy and severe droughts.(2) In the 1960 s,1980 s and early 21^(st) century,the number of droughts increased significantly,and the SPI values showed a significant decrease.(3) The 3-month time scale range was wide,during which the frequency of occurrence was high.The trend of SPI changes at the 12-month time scale was affected by the accumulation of antecedent precipitation,and the change was slow.The research results can provide a scientific reference for arid climate analysis and water resources management in agriculture and production in inland areas of Shandong Province.
基金Supported by Colleges and universities scientific research project of Shandong(J18KA197)
文摘Air pollution has become the most concerned regional environmental problem in China at present.According to the data of typical cities in Shandong Province from January,2014 to December,2015,the air quality status,pollution status and spatial variation characteristics of air pollutants were classified and analyzed,thereby providing a scientific basis for air pollution control.The conclusions of this study are as follows:(1) PM_(2.5) was the most important atmospheric pollutant in Shandong Province;(2) Qingdao had the best air quality with a good air quality rate of 73.7%,while Jinan had the worst air quality with a good air quality rate only of 31.3%; and(3) the days with heavy pollution were mainly concentrated in winter,mainly due to coal-fired heating in winter.
文摘[Objectives] To analyze and study the characteristics of rural labor flow to the tourism industry in Taian City of Shandong Province,and propose some measures for solving the problems of labor support in the development of rural tourism in Taian City. [Methods]The indicators were analyzed using the time series based on the relevant data on the labor employment and flow of rural households in Taian City in2005-2013. [Results] In Taian City,the number of rural laborers engaged in the primary industry decreased at the rate of 96 people/year,while the number of laborers engaged in the secondary and tertiary industries increased at the rate of 29 people/year and 3 people/year,respectively. The proportion of the three traditional tourism elements of transportation,lodging and catering in the tourism industry has been fluctuating,and the minimum was not lower than 30%. The recreational category was decreasing year by year,and only accounted for 1.7% in 2010.In summary,in the development of rural tourism in Taian City,the labor flow has problems such as low rural social security,weak attraction to young people,and large psychological barriers to returning to the hometown for employment. [Conclusions] In view of the problems,it is recommended to implement the rural revitalization strategy,attach importance to regional labor competition,give full play to the advantages of tourist cities,highlight product characteristics,increase cultural added value and improve the quality of operators to develop rural tourism. This study is intended to provide a scientific reference for talent support for rural revitalization in Taian City.
文摘[Objectives]To evaluate the effectiveness of Rain Classroom intelligent teaching in the course of Spring Water Tourism Resources.[Methods]The course of Spring Water Tourism Resources in the course of Overview of Tourism Resources was taken as an example,the pre-class preparation,in-class teaching,and after-class evaluation links were designed separately through the Rain Classroom platform.Then,a questionnaire survey was carried out for the students of Spring Water Tourism Resources.[Results]About 58.3%of the students believed that the greatest advantage of using the Rain Classroom teaching platform is that the learning method is flexible and can improve the ability of independent learning;61.78%of students stated that playing 3D animation in the classroom has the best effect for learning different tourism resources;with the aid of the Rain Classroom platform,the communication between teachers and students becomes more timely,and the students' ability to deal with practical problems can be practiced.[Conclusions]This study is intended to build an intelligent classroom model suitable for tourism management department based on the Rain Classroom platform.It is recommended to promote and apply this model in the teaching of tourism management.
文摘Taking the knowledge points of hotel construction site selection as an example,this paper integrated the information-based teaching method with traditional classrooms.With the aid of virtual reality(VR)technology,the information-based teaching can turn the abstract knowledge into vivid knowledge.Using the Rain Classroom platform,teachers can communicate with students in a better manner.Combined with the powerful spatial data analysis function of geographic information system(GIS)software,it is intended to provide new ideas and perspectives for the effective integration of traditional teaching classrooms and information technology,and effectively apply them to the practical teaching process.
基金Supported by Scientific Research Program of Colleges and Universities in Shandong Province(J18KA197)Tai an Science and Technology Innovation Development Project(Policy Guidance)(2020ZC322)Key Project of Art and Science of Shandong Province(ZD202008364).
文摘This paper selects Qingdao Textile Valley as the research object,establishes the evaluation system of industrial heritage tourism resources,and analyzes the evaluation factors of industrial heritage tourism resources,such as resource element value,market location value,and environmental factors.Then this paper puts forward some effective suggestions to promote the development of industrial heritage tourism in Textile Valley.The results show that the measures put forward,such as fully tapping the value of resource elements,improving the surrounding traffic environment,perfecting tourism signs,perfecting local traffic routes,improving the complementarity of tourism resources,and expanding the tourist market,can scientifically and effectively protect urban industrial heritage,improve the development level of urban tourism,and speed up the transformation of new and old energy in Qingdao.
基金Project supported by the National Key Research and Development Program of China(2019YFC0605000)the"Transformational Technologies for Clean Energy and Demonstration",Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21000000)+4 种基金the Independent Deployment Project of Ganjiang Innovation Research Institute of Chinese Academy of Sciences(E055A002)the Independent Deployment Project of China Fujian Innovation Laboratory of Optoelectronic Information Technology(2021ZZ109)the Fujian Provincial Natural Fund(2021J05101)the National Natural Science Foundation of China(21771196,62275276)Advanced Energy Science and Technology Guangdong Laboratory(HND20TDGFDC00)。
文摘The electrical properties of high-entropy ceramics(HECs)have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy engineering.Novel high-entropy(Sm_(0.2)Eu_(0.2)Gd_(0.2)Ho_(0.2)Yb_(0.2))CrO_(3)(HE-RECrO_(3))nanofibers were prepared by electro spinning.This work demonstrates that HE-RECrO_(3)nanofibe rs were successfully synthesized at a low temperature(800℃),which is approximately 400℃lower than the temperatures at which chromate ceramics were synthesized via the sol-gel method and the solid-state reaction method.The resistivity of HE-RECrO_(3)nanofibers decreases exponentially with increasing temperature from 25 to600℃.The logarithm of the resistivity is linearly related to the inverse of the temperature,confirming the negative temperature coefficient property of HE-RECrO_(3)nanofibers.The B_(25/50)value of the HERECrO_(3)nanofibers reaches 4072 K.In conclusion,HE-RECrO_(3)nanofibers are expected to be potential candidates for negative-temperature-coefficient(NTC)thermistors.
基金financially supported by the National Natural Science Foundation of China for Science Center Program (No. 21788102)Creative Research Groups (No. 21421004)+4 种基金Key Project (No. 21636002)Shanghai Pujiang Program (No. 20PJ1402900)National key Research and Development Program (No. 2016YFA0200300)Shanghai Municipal Science and Technology Major Project (No. 2018SHZDZX03)Program of Introducing Talents of Discipline to Universities (No. B16017)。
文摘The development of solid-state smart materials, in particular those showing photoresponsive luminescence, is highly desirable for their cutting edge applications in displays, sensors, data-storage, and anticounterfeiting. However, to achieve both excellent photoresponsive performance and bright luminescence in solid state remains challenge. Herein, we integrate a novel photochromic fluorophore YL into flexible polymer chains, thereby enabling the resultant polymer PYL with reversible photoisomerization upon aggregation. Remarkably, the polymer PYL possesses excellent photochromic properties and aggregationinduced emission(AIE) activity, which can be attributed to the photoactive YL moiety. Upon light exposure, its film exhibits reversibly off-to-on fluorescent modulation with quick response, high emission efficiency and signal contrast, sharply different from the weak emission in solution. The novel photoresponsive AIE polymer with invisible/visible color and fluorescence transformation allows for advanced anti-counterfeiting applications. This work provides an efficient platform for constructing solid-state photocontrollable luminescent materials.
基金supported by the National Natural Science Foundation of China(21878087,21908060)the Innovation Program of Shanghai Municipal Education Commission,Shuguang Program(18SG27)。
文摘Uniting dual-modality of fluorescence and photoacoustic(PA)imaging into theranostic nanoprobes is imperative for spatiotemporally tracking of drug delivery,distribution,and release.Herein,we present a rational design strategy of molecularly precise amphiphilic prodrugs BP_(n)-Cy-S-CPT(n=0,5,and 20,refers to the degree of polyethylene glycol(PEG)polymerization;CPT=camptothecin)to tune their self-assembly behaviour,innovatively integrating dual-modal PA and near-infrared(NIR)fluorescence imaging in a single-molecular framework.Among these elaborately designed prodrugs,it is found that only BP_(20)-Cy-S-CPT could form uniform and highly stable self-assemblies,especially in showing synergistically enhanced PA and dualchannel NIR signals.In detail,PA signal is employed to trace the in vivo delivery with high spatial resolution,meanwhile the glutathione(GSH)-triggered dual-channel fluorescence response could real-timely monitor drug distribution and release without"blind spot".The results of in vivo dual-modal PA/NIR imaging have verified that BP_(20)-Cy-S-CPT displayed synergistic targeting(including passive,active,and activatable targeting)for tumor-specific delivery,and thereby executed CPT release in the tumor site.Consequently,our molecularly precise BP_(20)-Cy-S-CPT self-assemblies could make a breakthrough to spatiotemporally track the in vivo drug release profile,expanding the intelligent theranostic toolbox for precise cancer treatment.
基金supported by the NSFC Science Center Program (21788102)NSFC/China (91959202, 21974047, and 21622602)Shanghai Municipal Science and Technology Major Project (2018SHZDZX03)
文摘Image guided photodynamic therapy(PDT)combines fluorescence tracing and phototherapy,which can achieve a more accurate and effective treatment effect.However,traditional photosensitizers are limited by the aggregation-caused fluorescence quenching(ACQ)effect and low reactive oxygen species(ROS)generation in a hypoxic environment,resulting in poor imaging and treatment effect.Herein,we report a tricyano-methylene-pyridine(TCM)-based Type I aggregation-induced emission(AIE)photosensitizer(TCM-MBP),the strong elec-tron acceptance(D-A)effect extends the wavelength to near-infrared(NIR)region to reduce the autofluorescence interference,and oxygen atoms provide lone pair electrons to enhance the inter system crossing(ISC)rate,thereby promoting the generation of more triplet states to produce ROS.The AIE photosensitizer TCM-MBP exhibited low oxygen dependence,NIR emission,and higher ROS production compared to commercially avail-able Ce_(6) and RB.After encapsulation with DSPE-PEG 2000,TCM-MBP nanoparticles(TCM-MBP NPs)could penetrate to visualize cells and efficiently kill cancer cells upon light irradiation.This study provides an oxygen-independent AIE photosensitizer,which has great potential to replace the commercial ACQ photosensitizers.
基金supported by the Fundamental Research Funds for the Central Universities(2632022YC01,to A.L.)Research Start-up Funds from China Pharmaceutical University(3150120048,to A.L)+2 种基金Shanghai Pujiang Talent Program(2020PJD068,to A.L)the National Natural Science Foundation of China(82061138008,to W.T.)Beijing Municipal Science and Technology Project(Z211100002521017).
文摘Dear Editor,Growing evidence has indicated that heterologous COVID-19 vaccination could generate higher antibody(Ab)and cellmediated immune(CMI)responses than homologous vaccination regimen.1–3 However,fundamental understanding of immunological mechanisms dictating the enhanced vaccine immunity is still lacking.To gain mechanistic insights,we comprehensively profiled the immune responses generated by homologous or heterologous booster vaccination in mice(Fig.1a).
基金supported by the NSFC Science Center Program(no.21788102)NSFC Major Research Project(no.91959202)+6 种基金National Key Research and Development Program(no.2016YFA0200300)NSFC/China(nos.21974047 and 21622602)Pujiang Talents Plan(no.19PJ1402300)China Postdoctoral Science Foundation(no.2020M671328)Postdoctoral Science Foundation of Jiangsu Province(no.2020Z189)Shanghai Municipal Science and Technology Major Project(no.2018SHZDZX03)Program of Introducing Talents of Discipline to Universities(no.B16017).
文摘High-fidelity spatiotemporal monitoring of the cell membrane is critically important.However,commercial fluorescence probes are stalked by the aggregation-caused quenching(ACQ)effect,and the reported aggregation-induced emission(AIE)-active probes are always limited by nonspecific aggregations in the biological environment.Herein,we report the rational molecular design of a stateof-the-art amphiphilic AIE luminogen(AIEgen),membrane tracker QMC12,using a core quinolinemalononitrile(QM)structure to suppress the ACQ effect,incorporate a positively charged pyridinium to regulate dispersity and strengthen the binding affinity to the negatively charged cell membrane,and extend the alky chain to improve the anchoring ability to the cell membrane.The membrane tracker QMC12,which disperses well in both hydrophilic and lipophilic environments,not only achieves minimal background interference and high signal-to-noise(S/N)ratio in the“ultrafast”visualization of the cell membrane,but also endows a“wash-free”characteristic.Furthermore,it realizes a spatial three dimensional(3D)view in a multicellular spheroid model and morphology changes over time.Moreover,QMC12 avoids false staining and signal loss and unprecedentedly achieves the direct observation of the cell membrane’s microstructure,which could elucidate spatiotemporal 3D model studies of the intercellular information exchange.
基金National Natural Science Foundation of China,Grant/Award Number:51903052Shanghai Pujiang Project,Grant/Award Number:19PJ1400700+4 种基金Zhejiang Provincial Natural Science Foundation of China,Grant/Award Number:LR17F050001the National Science Foundation of China,Grant/Award Numbers:21788102,21805002,61735016,61975172the Research Grants Council of Hong Kong,Grant/Award Numbers:16305518,16304819,N-HKUST609/19,A-HKUST605/16,C6009-17GInnovation and Technology Commission,Grant/Award Numbers:ITC-CNERC14SC01,ITCPD/17-9Science and Technology Plan of Shenzhen,Grant/Award Number:JCYJ20200109110608167。
文摘Kasha’s rule,which states that all exciton emissions occur from the lowest excited state and are independent of excitation energy,makes high-energy excitons difficult to use and severely hinders the widespread applications of organic photoluminescent materials in the real world.For decades,scientists have tried to break this rule to unleash the power of high-energy excitons,but only minimal progress has been achieved,with no rational guiding principles provided,and few applications developed.So far,breaking Kasha’s rule has remained a purely academic concept.In this paper,we introduce a design principle for a purely organic anti-Kasha system and synthesise a series of compounds based on the design rule.As predicted,these compounds all display evident S_(2) emissions in dilute solutions.In addition,we introduce a highly accurate(over 90%)convolutional neural network as an assistant for the classification of cells using anti-Kasha luminogens,thereby providing a new application direction for anti-Kasha systems.
