The excessive expansion of urbanized areas has resulted in haphazard land utili- zation, immoderate consumption of superior agricultural land and water resources, significant fragmentation of agricultural landscape, a...The excessive expansion of urbanized areas has resulted in haphazard land utili- zation, immoderate consumption of superior agricultural land and water resources, significant fragmentation of agricultural landscape, and gradual deterioration of the agro-ecological en- vironment. Combined, these factors cause poor land use efficiency. Under these circum- stances, comprehensively assessing land use efficiency for urban agriculture is a key issue in land use research. Currently, evaluation methods for agricultural land use efficiency narrowly concentrate on aspects of economic input and output. However, urban agro-ecosystems can provide diverse economic, social, and ecological services and functions. In particular, the social and ecological services and functions originating from agricultural land, which have a higher value than economic services, play a significant role in ensuring regional social, eco- logical, and environmental security. However, recent research has rarely taken these benefits into consideration. Therefore, land use value has been greatly underestimated, which has resulted in mishandled and poor land use policies. In this study, we apply Landsat imagery and social and economic statistical data for the Xi＇an metropolitan zone （XMZ） to investigate agricultural multi-functionality. We develop an evaluation framework for urban agricultural land use efficiency and identify agro-ecosystem services and functions as important outputs from agricultural land. The land use efficiency of urban agriculture is then evaluated using ecosystem services models, providing a mechanism for assessing spatial-temporal changes in land use efficiency in the XMZ from 1999 to 2015. Four important conclusions are reached from this analysis. First, the rapid urbanization and agricultural transformation from traditional cereal cultivation to modern urban agriculture has resulted in steadily increasing costs, out- puts, and land use efficiency of urban agriculture. The total output value increased 41% and land use efficiency per hectare increased by 33.13% on average. Second, the spatial patterns of comprehensive output and land use efficiency were dominated by economic outputs from agricultural land. Areas near cities, which are dominated by orchard and arable land, provide more economic functions. These areas support and regulate services due to the transforma- tion from extensive cereal production to intensive modern urban agriculture; therefore, they have higher output value and land use efficiency. In contrast, areas distant from cities, towns, and high traffic roads, namely, remote rural areas, provide more support and regulating ser- vices, but have relatively lower economic function due to inaccessibility tO urban markets and slow agricultural transformation. Therefore, these areas have lower output value and land use efficiency. The spatial change in agricultural output and land use efficiency in urban areas is strongly dependent on the degree of urbanization and agricultural transformation. Third, the total output value and land use efficiency of urban agriculture measured with our approach are much higher than evaluations using traditional methods. However, the spatial patterns measured using the two approaches are in agreement. The evaluation framework integrates ecological services and economic and social functions into a comprehensive output from agricultural land. This approach is more methodical and accurate for evaluating the compre- hensive efficiency of land use based on quantities and spatial scale because they are at the pixel scale. Finally, the evaluation results have important implications for enhancing current agricultural subsidies and even implementing ecological payment policies in China. Most importantly, they can be directly applied to agricultural transformation regulations, decision-making, and guidance for rational land utilization.展开更多
Multi-functional Al-matrix composites with high volume fraction （55%-57%） of SiC particles are produced with the new pressureless infiltration fabrication technology. X-ray detection and microscopic observation disp...Multi-functional Al-matrix composites with high volume fraction （55%-57%） of SiC particles are produced with the new pressureless infiltration fabrication technology. X-ray detection and microscopic observation display the composites which are macroscopically homogeneous without porosity. The investigation further reveals that the SiC/Al composites possess low density （2.94 g/cm^3）, high elastic modulus （220 GPa）, prominent thermal management function as a result of low coefficient of thermal expansion （8 × 10^4 K^-1） and high thermal conductivity （235 W/（m.K）） as well as unique preventability of resonance vibration. By adopting a series of developed techniques, the multi-functional SiC/Al composites have managed to be made into near-net-shape parts. Many kinds of precision components of space-based optomechanical structures and airborne optoelectronic platform have been turned out. Of them, several typical products are being under test in practices.展开更多
We proposed a vanadium dioxide(VO2)-integrated multi-functional metamaterial structure that consists of three metallic grating layers and two VO2 films separated by SiO2 dielectric spacers.The proposed structure can b...We proposed a vanadium dioxide(VO2)-integrated multi-functional metamaterial structure that consists of three metallic grating layers and two VO2 films separated by SiO2 dielectric spacers.The proposed structure can be flexibly switched among three states by adjusting temperature,incident direction,and polarization.In state 1,the incident wave is strongly transmitted and perfectly converted to its orthogonal polarization state.In state 2,the incident wave is perfectly absorbed.In state 3,incident wave is totally reflected back.The working frequency of the multi-functional metamaterial can be arbitrarily tuned within a broad pass band.We believe that our findings are beneficial in designing temperature-controlled metadevices.展开更多
To cope with the problem of emitter identification caused by the radar words＇ uncertainty of measured multi-function radar emitters, this paper proposes a new identification method based on stochastic syntax-directed...To cope with the problem of emitter identification caused by the radar words＇ uncertainty of measured multi-function radar emitters, this paper proposes a new identification method based on stochastic syntax-directed translation schema（SSDTS）. This method, which is deduced from the syntactic modeling of multi-function radars, considers the probabilities of radar phrases appearance in different radar modes as well as the probabilities of radar word errors occurrence in different radar phrases. It concludes that the proposed method can not only correct the defective radar words by using the stochastic translation schema, but also identify the real radar phrases and working modes of measured emitters concurrently. Furthermore, a number of simulations are presented to demonstrate the identification capability and adaptability of the SSDTS algorithm.The results show that even under the condition of the defective radar words distorted by noise,the proposed algorithm can infer the phrases, work modes and types of measured emitters correctly.展开更多
The binary random in-chain silyl-hydride multi-functionalized poly（styrene/butadiene/isoprene and dimethyl[4-（1-phenylvinyl） phenyl]silane） （PS-DPESiH, PB-DPESiH, PI-DPESiH） copolymers were successfully synthesi...The binary random in-chain silyl-hydride multi-functionalized poly（styrene/butadiene/isoprene and dimethyl[4-（1-phenylvinyl） phenyl]silane） （PS-DPESiH, PB-DPESiH, PI-DPESiH） copolymers were successfully synthesized. These functionalized copo- lymers were prepared in hexane with n-BuLi as the initiator at 50℃ for 4 h. The silyl-hydride groups were introduced into polymer backbones quantitatively by living anionic polymerization. The copolymers were determined through 1H NMR, size exclusion chromatography （SEC） and differential scanning calorimetry （DSC） techniques, while the number of silyl-hych-ide groups was calculated and discussed.展开更多
Fiber-shaped supercapacitors(FSSCs)show great potential in portable and wearable electronics due to their unique advantages of high safety,environmental friendliness,high performances,outstanding flexibility and integ...Fiber-shaped supercapacitors(FSSCs)show great potential in portable and wearable electronics due to their unique advantages of high safety,environmental friendliness,high performances,outstanding flexibility and integrability.They can directly act as the power sources or be easily integrated with other flexible devices to constitute self-powered and sustainable energy suppliers,providing excellent adaptability to irregular surfaces.This review mainly summarizes the recently reported works of FSSCs including preparation methods of various fiber electrodes,construction strategies of FSSCs and multi-functional device integrations,exploration of reaction mechanisms and strategies to improve the electrochemical performance and provision of suggestions on further designing and optimization of FSSCs.Meanwhile,it shares our perspectives on challenges and opportunities in this field,shedding light on the development of high-performance fiber-shaped supercapacitors with multifunctions.展开更多
We demonstrate a fiber-loop ring down multi-function sensors system, which can be used to measure refractive index and curvature simultaneously. Good agreement has been found between theoretical analyses and experimen...We demonstrate a fiber-loop ring down multi-function sensors system, which can be used to measure refractive index and curvature simultaneously. Good agreement has been found between theoretical analyses and experimental results. It has great potential for sensor applications.展开更多
Responsibility is a function of power, impact and knowledge. The more strategically central one’s position is in terms of power, influence and knowledge, the higher his or her responsibility would be. This is an idea...Responsibility is a function of power, impact and knowledge. The more strategically central one’s position is in terms of power, influence and knowledge, the higher his or her responsibility would be. This is an idea which can be worked out in more detail by using distributive models of graph theory and predistribution assignments of rights and duties according to different levels.展开更多
Interdisciplinary studies and cooperations are necessary for practical work as well as studies in geodesy. Responsibility is a function of power, impact and knowledge. The more strategically central one’s position is...Interdisciplinary studies and cooperations are necessary for practical work as well as studies in geodesy. Responsibility is a function of power, impact and knowledge. The more strategically central one’s position is in terms of power, influence and knowledge, the higher one’s responsibility is. This is an idea which can be worked out in more detail by using interdisciplinary approaches and distributive models on different levels. Social traps, Prisoners’ Dilemma situations, etc, as pertaining to land, soil, and environment as well as some examples from geodesics and the study of the usage of nature systems like lakes and flood plain areas are discussed regarding responsibility and distribution problems.“Naturalists’ Dilemmas”(or “Enjoyers’ Dilemmas”) are sketched and potentially solved by proposing a viable distribution strategy.展开更多
The issue of bycatch in the fisheries sector has been a major concern for the marine biologists over few decades in terms of conservation of marine eco-system and sustainability of the fisheries sector and marine biod...The issue of bycatch in the fisheries sector has been a major concern for the marine biologists over few decades in terms of conservation of marine eco-system and sustainability of the fisheries sector and marine biodiversity.As far as the concept of Bycatch is concerned,these are the unwanted species having less commercial importance,which in most of the cases disposed into the seas onboard or are caught during fishing.The article discusses the social,economic,cultural,and environmental impacts in addressing the issue of bycatch.The concern regarding bycatch is relatively new in the horizon in Indian perspective though it is often considered a major issue faced by developed nations since long.The problem of bycatch poses a serious threat to livelihoods and food security as it acts as a precursor to depletion of the food sources for local consumption with adverse social,economic,cultural,and environmental impacts.The adverse effects of by-catch can be mitigated through commercialisation of bycatch and making profits from the sale of bycatch,opening up of new markets for bycatch species or products,uses of bycatch as fishmeal and application of bycatch reduction devices(BRDs).Reorientation of the present monitoring system to collect fisheries data,strengthening technical know-how,bringing effective policy intervention,efficient co-management,and sincere and honest efforts in reducing bycatch and discards may provide a considerable impact towards sustainability of marine eco-system.展开更多
Global warming and energy crisis are two major challenges in the new-century.Wearable materials that enable all-seasonal self-adapting thermal comfort without additional energy-input attract significant attention as a...Global warming and energy crisis are two major challenges in the new-century.Wearable materials that enable all-seasonal self-adapting thermal comfort without additional energy-input attract significant attention as a solution to the increasing severity of extreme climate-change.Inspired by autologous temperature-regulation and multidimensional-sensing origins of nature-skin composed of nature collagen fibers,this study engineered a nanoscale wearable natural fibers-derived thermochromic material(TMEH-skin)for robust all-season self-adapting thermal management by tactically integrating traditional immersion and spraying methods with layer-by-layer stacking-strategy.Because of the on-demand multi-functional layer-structure design,TMEH-skin achieves spontaneous~38.16%visible lightmodulation and~95.1%infrared-emission,demonstrating outstanding double-self-switching thermal management origins by simple color-changing without additional energy-input.Moreover,TMEH-skin has gratifying tensile strength of 13.18 MPa,water vapor permeability,electrical-conductivity,and hydrophobicity,further broadening the application potential and scenarios as wearable materials.In applications for military-missions or reconnaissance behind enemy-lines,TMEH-skin robustly integrates the multi-functionalities of wearing-comfort,physiological signal-response capability for accurate transmission of Morse-code,and thermal management performances under special circumstances,indicating its tremendous potential for smart military-applications.Simulation results show that TMEH-skin has prominent energy-saving efficiency in cities with different climate zones.This study provides a new reference to the booming innovation of natural-derived wearable materials for all-seasonal self-adapting thermal management.展开更多
Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance an...Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance and plant growth-promoting traits,was isolated from abandoned mine soil.Strain ME1 exhibited growth at concentrations of Zn up to 250 mg/L,Cd and Pb up to 100 mg/L,and Cr up to 50 mg/L.It had the ability to produce the plant hormone indole-3-acetic acid and siderophores along with 1-aminocyclopropane-1-carboxylic acid deaminase and protease activities.Additionally,it showed antioxidant activity,including catalase and 2,2-diphenyl-1-picryhydrazyl(DPPH)scavenging activities.The optimal conditions for melanin production by ME1 were a pH of 7 and a temperature of 35℃.At 1000 mg/L,ME1-extracted melanin exhibited DPPH radical scavenging activity of(25.040±0.007)%,a sun protection factor of 15.200±0.260,and 19.6%antibacterial activity against the plant pathogen Xanthomonas campestris.Furthermore,its adsorption capacity was(0.235±0.073)mg/g melanin for Zn and(0.277±0.008)mg/g melanin for Ni.In plants of Brassica chinensis grown under conditions of hydroponic cultivation with single heavy metal contamination of Cd,Zn,Pb,or Cr,the removal efficiency of each heavy metal was improved by 0.1–1.8 times after 3 d following inoculation with the strain ME1 compared to the plants grown under the same conditions without inoculation.In addition,ME1 inoculation improved the removal efficiency of each heavy metal by 0.1–1.0 times under multiple heavy metal contamination conditions.These findings suggest that Acinetobacter sp.ME1 could be used to enhance phytoremediation efficiency in heavy metal-contaminated soils.Moreover,the melanin it produces also holds promise in cosmetics,household products,and medical applications due to its photoprotective,antioxidant,and antimicrobial properties.展开更多
Metamaterials,owing to their exceptional physical characteristics that are absent in natural materials,have emerged as a crucial constituent of intelligent devices and systems.However,there are still significant chall...Metamaterials,owing to their exceptional physical characteristics that are absent in natural materials,have emerged as a crucial constituent of intelligent devices and systems.However,there are still significant challenges that necessitate immediate attention,as they have considerably constrained the applicability of metamaterials,including fixed mechanical properties post-fabrication and restricted design freedom.Here,thermo-responsive,photo-responsive,electro-responsive,and magneto-responsive shape memory polymer nano-composites were developed,and shape memory gradient metamaterials were fabricated using multi-material 4D printing technology.The correlation mechanism between the design parameters and the mechanical properties of multi-responsive gradient metamaterials was systematically analyzed,and the highly designable and programmable configuration and mechanical properties of the gradient metamaterials were realized.More importantly,4D printed multi-responsive shape memory polymer gradient metamaterials can be programmed in situ without additional infrastructure for multi-functional mechanical functions,paving the way for the realization of multiple functions of a single structure.Based on the multi-responsive gradient metamaterials,4D printed digital pixel metamaterial intelligent information carriers were fabricated,featuring customizable encryption and decryption protocols,exceptional scalability,and reusability.Additionally,4D printed gradient metamaterial logic gate electronic devices were developed,which were anticipated to contribute to the development of smart,adaptable robotic systems that combine sensing,actuation,and decision-making capabilities.展开更多
Population growth,loss of biodiversity,and climate change necessitate a new vision for the future of both agriculture and biodiversity.In order to safeguard and support the world＇s agricultural heritage systems,in 20...Population growth,loss of biodiversity,and climate change necessitate a new vision for the future of both agriculture and biodiversity.In order to safeguard and support the world＇s agricultural heritage systems,in 2002 the FAO started an initiative for the conservation and adaptive management called Globally Important Agricultural Heritage Systems （GIAHS）.Tourism is suggested as part of the future as it is considered to be an alternative income source that will not only promote local economic development,but also provide the opportunity for tourists to learn about agriculture and ecology.However,inappropriate tourism in GIAHS sites will bring impacts on local culture and living styles,which not only threatens tourism＇s sustainable development,but also has the potential to damage these unique agricultural systems.This paper proposes that agriculture-based tourism is suitable for GIAHS and that Multi-functionality of Agriculture （MFA） can be the link between agriculture and tourism.This study constructs the framework for tourism development in GIAHS through MFA and applies it to the four GIAHS sites in China.Referring to the quantitative assessment for MFA and a qualitative analysis of the relationship between agriculture and tourism,we can give advice on agricultural tourism development in GIAHS sites.This framework also offers a universal methodology that allows stakeholders to communicate about the multiple functions of GIAHS across scales.展开更多
After the discussion of accomplishments of ecological urban construction in Suzhou City, the current ecological urban construction in Suzhou has been compared with the national standard for ecological urban constructi...After the discussion of accomplishments of ecological urban construction in Suzhou City, the current ecological urban construction in Suzhou has been compared with the national standard for ecological urban construction. According to the actual situation of Suzhou urban construction, the health evaluation index system and standards for urban eco-system have been established based on natural, economic and social sub-system. By using mean square deviation, indexes' weights have been identified. After the quantitative research on the health condition of urban eco-system in Suzhou City from 2004 to 2008, it has found key problems existing in its ecological urban construction. The results show that Suzhou urban eco-system develops well in general, but the three sub-systems are coordinated with each other moderately, and natural sub-system suffers severe pressure.展开更多
On basis of analysis on agroforestry-animal husbandry ecosystem characters, the research explored nutrient flow model of material cycle and carbon cycle and agroforestry-animal husbandry mutualism model and supporting...On basis of analysis on agroforestry-animal husbandry ecosystem characters, the research explored nutrient flow model of material cycle and carbon cycle and agroforestry-animal husbandry mutualism model and supporting technology in Yangtze-Huaihe Region, taking Robinia pseudoacacia stand and rubber garden as an example.展开更多
[Objective] The aim is to conduct systematic diagnoses on the eco-vulnerability in Daqinggou National Natural Reserve. [Method] A kind of ＂problem pile＂ is proposed about 58 interrelated problems of ecological vulne...[Objective] The aim is to conduct systematic diagnoses on the eco-vulnerability in Daqinggou National Natural Reserve. [Method] A kind of ＂problem pile＂ is proposed about 58 interrelated problems of ecological vulnerability by field survey and questionnaires and a ladder diagram of interrelations among the problems is established. The root problems, basic problems, core problems, interrelation and solving approaches are proposed, as well. [Result] It can be concluded from system diagnosis that fragile ecosystem of the Reserve can be observed from poor disasterresistibility, lower species diffusivity, lower system metabolism and poor system restorability. According to system diagnoses, management planning and control subsystem is key for protection of system vulnerability and solving different problems in process-oriented system. Conservation of the Reserve and ecological education on tourists are indispensible. It can be concluded from diagnoses that plant updating, evolution and ill growth in the Reserve are the focus of the vulnerable ecosystem, which influence species diffusivity, system metabolism and restorability and constitute central nodes of process-oriented and effect-oriented subsystems. [Conclusion] The research provides references for solving vulnerability issues of conservation and tourism management in Daqinggou National Nature Reserve.展开更多
Eco-friendly electromagnetic wave absorbing materials with excellent thermal infrared stealth property,heat-insulating ability and compression resistance are highly attractive in practical applications.Meeting the afo...Eco-friendly electromagnetic wave absorbing materials with excellent thermal infrared stealth property,heat-insulating ability and compression resistance are highly attractive in practical applications.Meeting the aforesaid requirements simultaneously is a formidable challenge.Herein,ultra-light carbon aerogels were fabricated via fresh shaddock peel by facile freeze-drying method and calcination process,forming porous network architecture.With the heating platform temperature of 70℃,the upper surface temperatures of the as-prepared carbon aerogel present a slow upward trend.The color of the sample surface in thermal infrared images is similar to that of the surroundings.With the maximum compressive stress of 2.435 kPa,the carbon aerogels can provide favorable endurance.The shaddock peel-based carbon aerogels possess the minimum reflection loss value(RLmin)of−29.50 dB in X band.Meanwhile,the effective absorption bandwidth covers 5.80 GHz at a relatively thin thickness of only 1.7 mm.With the detection theta of 0°,the maximum radar cross-sectional(RCS)reduction values of 16.28 dB m^(2) can be achieved.Theoretical simulations of RCS have aroused extensive interest owing to their ingenious design and time-saving feature.This work paves the way for preparing multi-functional microwave absorbers derived from biomass raw materials under the guidance of RCS simulations.展开更多
The close phylogenetic relationship between humans and non-human primates makes non-human primates an irreplaceable model for the study of human infectious diseases.In this study,we describe the development of a large...The close phylogenetic relationship between humans and non-human primates makes non-human primates an irreplaceable model for the study of human infectious diseases.In this study,we describe the development of a large-scale automatic multi-functional isolation chamber for use with medium-sized laboratory animals carrying infectious diseases.The isolation chamber,including the transfer chain,disinfection chain,negative air pressure isolation system,animal welfare system,and the automated system,is designed to meet all biological safety standards.To create an internal chamber environment that is completely isolated from the exterior,variable frequency drive blowers are used in the air-intake and air-exhaust system,precisely controlling the filtered air flow and providing an air-barrier protection.A double door transfer port is used to transfer material between the interior of the isolation chamber and the outside.A peracetic acid sterilizer and its associated pipeline allow for complete disinfection of the isolation chamber.All of the isolation chamber parameters can be automatically controlled by a programmable computerized menu,allowing for work with different animals in different-sized cages depending on the research project.The large-scale multi-functional isolation chamber provides a useful and safe system for working with infectious medium-sized laboratory animals in high-level bio-safety laboratories.展开更多
With the rapid developments of the high-speed railway in China, a great number of long-span bridges have been constructed in order to cross rivers and gorges. At present, the longest main span of a constructed high-sp...With the rapid developments of the high-speed railway in China, a great number of long-span bridges have been constructed in order to cross rivers and gorges. At present, the longest main span of a constructed high-speed railway bridge is only 630 m. The main span of Hutong Yangtze River Bridge and of Wufengshan Yangtze River Bridge, which are under construction, will be much longer, at 1092 m each. In order to overcome the technical issues that originate from the extremely large dead loading and the relatively small structural stiffness of long-span high-speed railway bridges, many new technologies in bridge construction, design, materials, and so forth have been developed. This paper carefully reviews progress in the construction technologies of multi-function combined bridges in China, including com- bined highway and railway bridges and multi-track railway bridges. Innovations and practices regarding new types of bridge and composite bridge structures, such as bridges with three cable planes and three main trusses, inclined main trusses, slab-truss composite sections, and steel-concrete composite sections, are introduced. In addition, investigations into high-performance materials and integral fabrication and erection techniques for long-span railway bridges are summarized. At the end of the paper, prospects for the future development of long-span high-speed railwav bridges are provided.展开更多
基金National Natural Science Foundation of China, No.41271550 Humanities and Social Sciences Project of Ministry of Education in the West and the Frontier Areas, No. 12XJC790003
文摘The excessive expansion of urbanized areas has resulted in haphazard land utili- zation, immoderate consumption of superior agricultural land and water resources, significant fragmentation of agricultural landscape, and gradual deterioration of the agro-ecological en- vironment. Combined, these factors cause poor land use efficiency. Under these circum- stances, comprehensively assessing land use efficiency for urban agriculture is a key issue in land use research. Currently, evaluation methods for agricultural land use efficiency narrowly concentrate on aspects of economic input and output. However, urban agro-ecosystems can provide diverse economic, social, and ecological services and functions. In particular, the social and ecological services and functions originating from agricultural land, which have a higher value than economic services, play a significant role in ensuring regional social, eco- logical, and environmental security. However, recent research has rarely taken these benefits into consideration. Therefore, land use value has been greatly underestimated, which has resulted in mishandled and poor land use policies. In this study, we apply Landsat imagery and social and economic statistical data for the Xi＇an metropolitan zone （XMZ） to investigate agricultural multi-functionality. We develop an evaluation framework for urban agricultural land use efficiency and identify agro-ecosystem services and functions as important outputs from agricultural land. The land use efficiency of urban agriculture is then evaluated using ecosystem services models, providing a mechanism for assessing spatial-temporal changes in land use efficiency in the XMZ from 1999 to 2015. Four important conclusions are reached from this analysis. First, the rapid urbanization and agricultural transformation from traditional cereal cultivation to modern urban agriculture has resulted in steadily increasing costs, out- puts, and land use efficiency of urban agriculture. The total output value increased 41% and land use efficiency per hectare increased by 33.13% on average. Second, the spatial patterns of comprehensive output and land use efficiency were dominated by economic outputs from agricultural land. Areas near cities, which are dominated by orchard and arable land, provide more economic functions. These areas support and regulate services due to the transforma- tion from extensive cereal production to intensive modern urban agriculture; therefore, they have higher output value and land use efficiency. In contrast, areas distant from cities, towns, and high traffic roads, namely, remote rural areas, provide more support and regulating ser- vices, but have relatively lower economic function due to inaccessibility tO urban markets and slow agricultural transformation. Therefore, these areas have lower output value and land use efficiency. The spatial change in agricultural output and land use efficiency in urban areas is strongly dependent on the degree of urbanization and agricultural transformation. Third, the total output value and land use efficiency of urban agriculture measured with our approach are much higher than evaluations using traditional methods. However, the spatial patterns measured using the two approaches are in agreement. The evaluation framework integrates ecological services and economic and social functions into a comprehensive output from agricultural land. This approach is more methodical and accurate for evaluating the compre- hensive efficiency of land use based on quantities and spatial scale because they are at the pixel scale. Finally, the evaluation results have important implications for enhancing current agricultural subsidies and even implementing ecological payment policies in China. Most importantly, they can be directly applied to agricultural transformation regulations, decision-making, and guidance for rational land utilization.
基金Foundation items： High-technology Research and Development Programme of China （2007AA03Z544） Aeronautical Science Foundation of China （20075221001）
文摘Multi-functional Al-matrix composites with high volume fraction （55%-57%） of SiC particles are produced with the new pressureless infiltration fabrication technology. X-ray detection and microscopic observation display the composites which are macroscopically homogeneous without porosity. The investigation further reveals that the SiC/Al composites possess low density （2.94 g/cm^3）, high elastic modulus （220 GPa）, prominent thermal management function as a result of low coefficient of thermal expansion （8 × 10^4 K^-1） and high thermal conductivity （235 W/（m.K）） as well as unique preventability of resonance vibration. By adopting a series of developed techniques, the multi-functional SiC/Al composites have managed to be made into near-net-shape parts. Many kinds of precision components of space-based optomechanical structures and airborne optoelectronic platform have been turned out. Of them, several typical products are being under test in practices.
基金Project supported by the Scientific and Technological Developing Scheme of Jilin Province,China(Grant No.20180101281JC)the"135"Research Project of Education Bureau of Jilin Province,China(Grant No.JJKH20190579KJ)the"111"Project of China(Grant No.D17017).
文摘We proposed a vanadium dioxide(VO2)-integrated multi-functional metamaterial structure that consists of three metallic grating layers and two VO2 films separated by SiO2 dielectric spacers.The proposed structure can be flexibly switched among three states by adjusting temperature,incident direction,and polarization.In state 1,the incident wave is strongly transmitted and perfectly converted to its orthogonal polarization state.In state 2,the incident wave is perfectly absorbed.In state 3,incident wave is totally reflected back.The working frequency of the multi-functional metamaterial can be arbitrarily tuned within a broad pass band.We believe that our findings are beneficial in designing temperature-controlled metadevices.
基金supported by the National Natural Science Foundation of China (No. 61002026)
文摘To cope with the problem of emitter identification caused by the radar words＇ uncertainty of measured multi-function radar emitters, this paper proposes a new identification method based on stochastic syntax-directed translation schema（SSDTS）. This method, which is deduced from the syntactic modeling of multi-function radars, considers the probabilities of radar phrases appearance in different radar modes as well as the probabilities of radar word errors occurrence in different radar phrases. It concludes that the proposed method can not only correct the defective radar words by using the stochastic translation schema, but also identify the real radar phrases and working modes of measured emitters concurrently. Furthermore, a number of simulations are presented to demonstrate the identification capability and adaptability of the SSDTS algorithm.The results show that even under the condition of the defective radar words distorted by noise,the proposed algorithm can infer the phrases, work modes and types of measured emitters correctly.
基金sponsored by the National Natural Science Foundation of China(Nos.21034001,21174021)
文摘The binary random in-chain silyl-hydride multi-functionalized poly（styrene/butadiene/isoprene and dimethyl[4-（1-phenylvinyl） phenyl]silane） （PS-DPESiH, PB-DPESiH, PI-DPESiH） copolymers were successfully synthesized. These functionalized copo- lymers were prepared in hexane with n-BuLi as the initiator at 50℃ for 4 h. The silyl-hydride groups were introduced into polymer backbones quantitatively by living anionic polymerization. The copolymers were determined through 1H NMR, size exclusion chromatography （SEC） and differential scanning calorimetry （DSC） techniques, while the number of silyl-hych-ide groups was calculated and discussed.
基金upported by the National Natural Science Foundation of China(No.21875226)the Science Fund for Distinguished Young Scholars of Sichuan Province(No.2017JQ0036)the Chengdu Rongpiao Talent plan,the Sichuan'Ten-thousand Talents Program",the"QianYingBaiTuan"Plan of China Mianyang Science City,the Science Foundation of Institute of Chemical Materials(No.O11100301)the"Global Experts Recruitment"program.
文摘Fiber-shaped supercapacitors(FSSCs)show great potential in portable and wearable electronics due to their unique advantages of high safety,environmental friendliness,high performances,outstanding flexibility and integrability.They can directly act as the power sources or be easily integrated with other flexible devices to constitute self-powered and sustainable energy suppliers,providing excellent adaptability to irregular surfaces.This review mainly summarizes the recently reported works of FSSCs including preparation methods of various fiber electrodes,construction strategies of FSSCs and multi-functional device integrations,exploration of reaction mechanisms and strategies to improve the electrochemical performance and provision of suggestions on further designing and optimization of FSSCs.Meanwhile,it shares our perspectives on challenges and opportunities in this field,shedding light on the development of high-performance fiber-shaped supercapacitors with multifunctions.
文摘We demonstrate a fiber-loop ring down multi-function sensors system, which can be used to measure refractive index and curvature simultaneously. Good agreement has been found between theoretical analyses and experimental results. It has great potential for sensor applications.
文摘Responsibility is a function of power, impact and knowledge. The more strategically central one’s position is in terms of power, influence and knowledge, the higher his or her responsibility would be. This is an idea which can be worked out in more detail by using distributive models of graph theory and predistribution assignments of rights and duties according to different levels.
文摘Interdisciplinary studies and cooperations are necessary for practical work as well as studies in geodesy. Responsibility is a function of power, impact and knowledge. The more strategically central one’s position is in terms of power, influence and knowledge, the higher one’s responsibility is. This is an idea which can be worked out in more detail by using interdisciplinary approaches and distributive models on different levels. Social traps, Prisoners’ Dilemma situations, etc, as pertaining to land, soil, and environment as well as some examples from geodesics and the study of the usage of nature systems like lakes and flood plain areas are discussed regarding responsibility and distribution problems.“Naturalists’ Dilemmas”(or “Enjoyers’ Dilemmas”) are sketched and potentially solved by proposing a viable distribution strategy.
文摘The issue of bycatch in the fisheries sector has been a major concern for the marine biologists over few decades in terms of conservation of marine eco-system and sustainability of the fisheries sector and marine biodiversity.As far as the concept of Bycatch is concerned,these are the unwanted species having less commercial importance,which in most of the cases disposed into the seas onboard or are caught during fishing.The article discusses the social,economic,cultural,and environmental impacts in addressing the issue of bycatch.The concern regarding bycatch is relatively new in the horizon in Indian perspective though it is often considered a major issue faced by developed nations since long.The problem of bycatch poses a serious threat to livelihoods and food security as it acts as a precursor to depletion of the food sources for local consumption with adverse social,economic,cultural,and environmental impacts.The adverse effects of by-catch can be mitigated through commercialisation of bycatch and making profits from the sale of bycatch,opening up of new markets for bycatch species or products,uses of bycatch as fishmeal and application of bycatch reduction devices(BRDs).Reorientation of the present monitoring system to collect fisheries data,strengthening technical know-how,bringing effective policy intervention,efficient co-management,and sincere and honest efforts in reducing bycatch and discards may provide a considerable impact towards sustainability of marine eco-system.
基金the Institute of Biomass&Functional Materials of Shaanxi University of Science and Technology for funding this research workfinancially supported by the National Natural Science Foundation of China(2207081675,22278257,22308209)+1 种基金the Key R&D Program of Shaanxi Province(2024SF-YBXM-586)the Project of Innovation Capability Support Program in Shaanxi Province(2024ZC-KJXX-005)。
文摘Global warming and energy crisis are two major challenges in the new-century.Wearable materials that enable all-seasonal self-adapting thermal comfort without additional energy-input attract significant attention as a solution to the increasing severity of extreme climate-change.Inspired by autologous temperature-regulation and multidimensional-sensing origins of nature-skin composed of nature collagen fibers,this study engineered a nanoscale wearable natural fibers-derived thermochromic material(TMEH-skin)for robust all-season self-adapting thermal management by tactically integrating traditional immersion and spraying methods with layer-by-layer stacking-strategy.Because of the on-demand multi-functional layer-structure design,TMEH-skin achieves spontaneous~38.16%visible lightmodulation and~95.1%infrared-emission,demonstrating outstanding double-self-switching thermal management origins by simple color-changing without additional energy-input.Moreover,TMEH-skin has gratifying tensile strength of 13.18 MPa,water vapor permeability,electrical-conductivity,and hydrophobicity,further broadening the application potential and scenarios as wearable materials.In applications for military-missions or reconnaissance behind enemy-lines,TMEH-skin robustly integrates the multi-functionalities of wearing-comfort,physiological signal-response capability for accurate transmission of Morse-code,and thermal management performances under special circumstances,indicating its tremendous potential for smart military-applications.Simulation results show that TMEH-skin has prominent energy-saving efficiency in cities with different climate zones.This study provides a new reference to the booming innovation of natural-derived wearable materials for all-seasonal self-adapting thermal management.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korean government,the Ministry of Science,and the Ministry of Science and Information and Communication Technology(ICT(MSIT))(Nos.2022R1A2C2006615 and RS2023-00217228).
文摘Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance and plant growth-promoting traits,was isolated from abandoned mine soil.Strain ME1 exhibited growth at concentrations of Zn up to 250 mg/L,Cd and Pb up to 100 mg/L,and Cr up to 50 mg/L.It had the ability to produce the plant hormone indole-3-acetic acid and siderophores along with 1-aminocyclopropane-1-carboxylic acid deaminase and protease activities.Additionally,it showed antioxidant activity,including catalase and 2,2-diphenyl-1-picryhydrazyl(DPPH)scavenging activities.The optimal conditions for melanin production by ME1 were a pH of 7 and a temperature of 35℃.At 1000 mg/L,ME1-extracted melanin exhibited DPPH radical scavenging activity of(25.040±0.007)%,a sun protection factor of 15.200±0.260,and 19.6%antibacterial activity against the plant pathogen Xanthomonas campestris.Furthermore,its adsorption capacity was(0.235±0.073)mg/g melanin for Zn and(0.277±0.008)mg/g melanin for Ni.In plants of Brassica chinensis grown under conditions of hydroponic cultivation with single heavy metal contamination of Cd,Zn,Pb,or Cr,the removal efficiency of each heavy metal was improved by 0.1–1.8 times after 3 d following inoculation with the strain ME1 compared to the plants grown under the same conditions without inoculation.In addition,ME1 inoculation improved the removal efficiency of each heavy metal by 0.1–1.0 times under multiple heavy metal contamination conditions.These findings suggest that Acinetobacter sp.ME1 could be used to enhance phytoremediation efficiency in heavy metal-contaminated soils.Moreover,the melanin it produces also holds promise in cosmetics,household products,and medical applications due to its photoprotective,antioxidant,and antimicrobial properties.
基金supported by the National Key R&D Program of China(2022YFB3805700)the National Natural Science Foundation of China(Grant No.12302198)+2 种基金China Postdoctoral Science Foundation(2022M720042)Heilongjiang Postdoctoral Science Foundation(LBH-Z22016)Key Project of Heilongjiang Provincial Department of Science and Technology(2022ZX02C25).
文摘Metamaterials,owing to their exceptional physical characteristics that are absent in natural materials,have emerged as a crucial constituent of intelligent devices and systems.However,there are still significant challenges that necessitate immediate attention,as they have considerably constrained the applicability of metamaterials,including fixed mechanical properties post-fabrication and restricted design freedom.Here,thermo-responsive,photo-responsive,electro-responsive,and magneto-responsive shape memory polymer nano-composites were developed,and shape memory gradient metamaterials were fabricated using multi-material 4D printing technology.The correlation mechanism between the design parameters and the mechanical properties of multi-responsive gradient metamaterials was systematically analyzed,and the highly designable and programmable configuration and mechanical properties of the gradient metamaterials were realized.More importantly,4D printed multi-responsive shape memory polymer gradient metamaterials can be programmed in situ without additional infrastructure for multi-functional mechanical functions,paving the way for the realization of multiple functions of a single structure.Based on the multi-responsive gradient metamaterials,4D printed digital pixel metamaterial intelligent information carriers were fabricated,featuring customizable encryption and decryption protocols,exceptional scalability,and reusability.Additionally,4D printed gradient metamaterial logic gate electronic devices were developed,which were anticipated to contribute to the development of smart,adaptable robotic systems that combine sensing,actuation,and decision-making capabilities.
基金financial support for this study by FAO/GEF project(GCP/GLO/212/GEF)project"rice-fish GIAHS dynamic conservation and adaptivemanagement"the National Public Benefit(Environmental)Research Foundation of China(201009020)
文摘Population growth,loss of biodiversity,and climate change necessitate a new vision for the future of both agriculture and biodiversity.In order to safeguard and support the world＇s agricultural heritage systems,in 2002 the FAO started an initiative for the conservation and adaptive management called Globally Important Agricultural Heritage Systems （GIAHS）.Tourism is suggested as part of the future as it is considered to be an alternative income source that will not only promote local economic development,but also provide the opportunity for tourists to learn about agriculture and ecology.However,inappropriate tourism in GIAHS sites will bring impacts on local culture and living styles,which not only threatens tourism＇s sustainable development,but also has the potential to damage these unique agricultural systems.This paper proposes that agriculture-based tourism is suitable for GIAHS and that Multi-functionality of Agriculture （MFA） can be the link between agriculture and tourism.This study constructs the framework for tourism development in GIAHS through MFA and applies it to the four GIAHS sites in China.Referring to the quantitative assessment for MFA and a qualitative analysis of the relationship between agriculture and tourism,we can give advice on agricultural tourism development in GIAHS sites.This framework also offers a universal methodology that allows stakeholders to communicate about the multiple functions of GIAHS across scales.
文摘After the discussion of accomplishments of ecological urban construction in Suzhou City, the current ecological urban construction in Suzhou has been compared with the national standard for ecological urban construction. According to the actual situation of Suzhou urban construction, the health evaluation index system and standards for urban eco-system have been established based on natural, economic and social sub-system. By using mean square deviation, indexes' weights have been identified. After the quantitative research on the health condition of urban eco-system in Suzhou City from 2004 to 2008, it has found key problems existing in its ecological urban construction. The results show that Suzhou urban eco-system develops well in general, but the three sub-systems are coordinated with each other moderately, and natural sub-system suffers severe pressure.
基金Supported by the National S&T Support Program during the Twelfth Five-year Pla Period(2012BAD14B13)~~
文摘On basis of analysis on agroforestry-animal husbandry ecosystem characters, the research explored nutrient flow model of material cycle and carbon cycle and agroforestry-animal husbandry mutualism model and supporting technology in Yangtze-Huaihe Region, taking Robinia pseudoacacia stand and rubber garden as an example.
基金Supported by State Forestry Administration"Public Welfare Program"(201204205)~~
文摘[Objective] The aim is to conduct systematic diagnoses on the eco-vulnerability in Daqinggou National Natural Reserve. [Method] A kind of ＂problem pile＂ is proposed about 58 interrelated problems of ecological vulnerability by field survey and questionnaires and a ladder diagram of interrelations among the problems is established. The root problems, basic problems, core problems, interrelation and solving approaches are proposed, as well. [Result] It can be concluded from system diagnosis that fragile ecosystem of the Reserve can be observed from poor disasterresistibility, lower species diffusivity, lower system metabolism and poor system restorability. According to system diagnoses, management planning and control subsystem is key for protection of system vulnerability and solving different problems in process-oriented system. Conservation of the Reserve and ecological education on tourists are indispensible. It can be concluded from diagnoses that plant updating, evolution and ill growth in the Reserve are the focus of the vulnerable ecosystem, which influence species diffusivity, system metabolism and restorability and constitute central nodes of process-oriented and effect-oriented subsystems. [Conclusion] The research provides references for solving vulnerability issues of conservation and tourism management in Daqinggou National Nature Reserve.
基金National Nature Science Foundation of China(No.51971111)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX20_0190).
文摘Eco-friendly electromagnetic wave absorbing materials with excellent thermal infrared stealth property,heat-insulating ability and compression resistance are highly attractive in practical applications.Meeting the aforesaid requirements simultaneously is a formidable challenge.Herein,ultra-light carbon aerogels were fabricated via fresh shaddock peel by facile freeze-drying method and calcination process,forming porous network architecture.With the heating platform temperature of 70℃,the upper surface temperatures of the as-prepared carbon aerogel present a slow upward trend.The color of the sample surface in thermal infrared images is similar to that of the surroundings.With the maximum compressive stress of 2.435 kPa,the carbon aerogels can provide favorable endurance.The shaddock peel-based carbon aerogels possess the minimum reflection loss value(RLmin)of−29.50 dB in X band.Meanwhile,the effective absorption bandwidth covers 5.80 GHz at a relatively thin thickness of only 1.7 mm.With the detection theta of 0°,the maximum radar cross-sectional(RCS)reduction values of 16.28 dB m^(2) can be achieved.Theoretical simulations of RCS have aroused extensive interest owing to their ingenious design and time-saving feature.This work paves the way for preparing multi-functional microwave absorbers derived from biomass raw materials under the guidance of RCS simulations.
基金Project supported by the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry (No. 2008-890-2)the National Natural Science Foundation of China (No. 30972633)
文摘The close phylogenetic relationship between humans and non-human primates makes non-human primates an irreplaceable model for the study of human infectious diseases.In this study,we describe the development of a large-scale automatic multi-functional isolation chamber for use with medium-sized laboratory animals carrying infectious diseases.The isolation chamber,including the transfer chain,disinfection chain,negative air pressure isolation system,animal welfare system,and the automated system,is designed to meet all biological safety standards.To create an internal chamber environment that is completely isolated from the exterior,variable frequency drive blowers are used in the air-intake and air-exhaust system,precisely controlling the filtered air flow and providing an air-barrier protection.A double door transfer port is used to transfer material between the interior of the isolation chamber and the outside.A peracetic acid sterilizer and its associated pipeline allow for complete disinfection of the isolation chamber.All of the isolation chamber parameters can be automatically controlled by a programmable computerized menu,allowing for work with different animals in different-sized cages depending on the research project.The large-scale multi-functional isolation chamber provides a useful and safe system for working with infectious medium-sized laboratory animals in high-level bio-safety laboratories.
文摘With the rapid developments of the high-speed railway in China, a great number of long-span bridges have been constructed in order to cross rivers and gorges. At present, the longest main span of a constructed high-speed railway bridge is only 630 m. The main span of Hutong Yangtze River Bridge and of Wufengshan Yangtze River Bridge, which are under construction, will be much longer, at 1092 m each. In order to overcome the technical issues that originate from the extremely large dead loading and the relatively small structural stiffness of long-span high-speed railway bridges, many new technologies in bridge construction, design, materials, and so forth have been developed. This paper carefully reviews progress in the construction technologies of multi-function combined bridges in China, including com- bined highway and railway bridges and multi-track railway bridges. Innovations and practices regarding new types of bridge and composite bridge structures, such as bridges with three cable planes and three main trusses, inclined main trusses, slab-truss composite sections, and steel-concrete composite sections, are introduced. In addition, investigations into high-performance materials and integral fabrication and erection techniques for long-span railway bridges are summarized. At the end of the paper, prospects for the future development of long-span high-speed railwav bridges are provided.
