The preparation of carbon-based electromagnetic wave(EMW)absorbers possessing thin matching thickness,wide absorption bandwidth,strong absorption intensity,and low filling ratio remains a huge challenge.Metal-organic ...The preparation of carbon-based electromagnetic wave(EMW)absorbers possessing thin matching thickness,wide absorption bandwidth,strong absorption intensity,and low filling ratio remains a huge challenge.Metal-organic frameworks(MOFs)are ideal self-sacrificing templates for the construction of carbon-based EMW absorbers.In this work,bimetallic FeMn-MOF-derived MnFe_(2)O_(4)/C/graphene composites were fabricated via a two-step route of solvothermal reaction and the following pyrolysis treatment.The results re-veal the evolution of the microscopic morphology of carbon skeletons from loofah-like to octahedral and then to polyhedron and pomegran-ate after the adjustment of the Fe^(3+)to Mn^(2+)molar ratio.Furthermore,at the Fe^(3+)to Mn^(2+)molar ratio of 2:1,the obtained MnFe_(2)O_(4)/C/graphene composite exhibited the highest EMW absorption capacity.Specifically,a minimum reflection loss of-72.7 dB and a max-imum effective absorption bandwidth of 5.1 GHz were achieved at a low filling ratio of 10wt%.In addition,the possible EMW absorp-tion mechanism of MnFe_(2)O_(4)/C/graphene composites was proposed.Therefore,the results of this work will contribute to the construction of broadband and efficient carbon-based EMW absorbers derived from MOFs.展开更多
Ecological conservation is at a crossroad as environmental stresses around the world intensify and traditional models of conservation exhibit intrinsic weaknesses in their response to present and future problems.In th...Ecological conservation is at a crossroad as environmental stresses around the world intensify and traditional models of conservation exhibit intrinsic weaknesses in their response to present and future problems.In the project,we evaluated novel approaches integrating adaptive management,technological innovations,and community-based action towards more efficient sustainable conservation results and ecosystem resilience.The multi-site experimental design was based on comparison between conventional reserve management and novel integrative models implemented in diverse ecological zones.Data were collected over a period of three years employing remote sensing technologies,in situ biodiversity assessments,and large socioeconomic surveys.These instruments enabled a robust and multi-dimensional measurement of variables such as species diversity,ecological resilience,community engagement,and stakeholder engagement.The results indicate that adaptive strategies significantly enhance real-time decision-making abilities and enhance long-term ecosystem resilience.Further,technology-driven monitoring greatly enhances data accuracy,responsiveness,and early warning capabilities.Besides that,community-based conservation initiatives were found to be pivotal in facilitating local stewardship,enhancing participatory governance,and enabling more adaptive and adaptive policy systems.This research rejects mainstream conservation paradigms by placing importance on flexibility,interdisciplinarity,and inclusivity of governance systems in effectively mitigating the impacts of climate change and loss of biodiversity.Our findings offer strong evidence that emerging paradigms of conservation can provide greater ecological and social sustainability than traditional methods.These results support the need for a paradigm shift towards conservation strategies that are dynamic,collaborative,and technologically integrated,with significant implications for policy formulation as well as operational environmental management.展开更多
This paper presents both analytical and numerical studies of the conservative Sawada-Kotera equation and its dissipative generalization,equations known for their soliton solutions and rich chaotic dynamics.These model...This paper presents both analytical and numerical studies of the conservative Sawada-Kotera equation and its dissipative generalization,equations known for their soliton solutions and rich chaotic dynamics.These models offer valuable insights into nonlinear wave propagation,with applications in fluid dynamics and materials science,including systems such as liquid crystals and ferrofluids.It is shown that the conservative Sawada-Kotera equation supports traveling wave solutions corresponding to elliptic limit cycles,as well as two-and three-dimensional invariant tori surrounding these cycles in the associated ordinary differential equation(ODE)system.For the dissipative generalized Sawada-Kotera equation,chaotic wave behavior is observed.The transition to chaos in the corresponding ODE systemfollows a universal bifurcation scenario consistent with the framework established by FShM(Feigenbaum-Sharkovsky-Magnitskii)theory.Notably,this study demonstrates for the first time that the conservative Sawada-Kotera equation can exhibit complex quasi-periodic wave solutions,while its dissipative counterpart admits an infinite number of stable periodic and chaotic waveforms.展开更多
This work focuses on a Keller-Segel chemotaxis model, with an emphasis on its conservation laws. Through a new approach combined with the multiplier method, called the mixed method, we obtain conservation vectors that...This work focuses on a Keller-Segel chemotaxis model, with an emphasis on its conservation laws. Through a new approach combined with the multiplier method, called the mixed method, we obtain conservation vectors that are related and unrelated to symmetric information. In addition, some exact solutions with particular forms are obtained according to the method of conservation laws. These particular solutions are different from the group-invariant solutions.展开更多
Disaster risk reduction,an essential function of protected areas(PAs),has been generally overlooked in PA design.Using primates as a model,we designed a disaster risk index(DRI)to measure the disaster sensitivity of p...Disaster risk reduction,an essential function of protected areas(PAs),has been generally overlooked in PA design.Using primates as a model,we designed a disaster risk index(DRI)to measure the disaster sensitivity of primate species.High-conservation-need(HCN)areas were identified by both their richness and number of threatened primate species.We also constructed high-disaster-risk(HDR)areas and climate-sensitive(CS)areas based on a disaster risk assessment and temperature change under climate change.We overlaid HCN and HDR areas to obtain HDR-HCN areas.We defined species conservation targets as the percent of each species’range that should be effectively conserved using“Zonation”.Landslides had the highest DRI(1.43±0.88),but have been overlooked in previous studies.PA coverage in HDR-HCN(30%)areas was similar to that in HCN areas(28%),indicating that current PA design fails to account for disaster risk reduction.About 50%of the HDR-HCN areas overlapped with CS areas.Presently,43%of primate species meet their conservation targets.Fifty-seven of primate species would meet their conservation targets and 67%of primates could benefit from PA expansion if HDR-HCN areas are fully incorporated into PAs.Increasing PA coverage in HDR-HCN areas is essential to achieving both primate conservation and disaster risk reduction.The study calls for integrating disaster risk reduction into PA design guidelines,particularly in regions like the western Amazon,and recommends flexible conservation approaches in other areas.展开更多
Effective preservation of Key Biodiversity Areas(KBAs)is crucial to address biodiversity loss.Human-induced disturbance in these vital sites can exacerbate species extinction and challenge the Kunming-Montreal Global ...Effective preservation of Key Biodiversity Areas(KBAs)is crucial to address biodiversity loss.Human-induced disturbance in these vital sites can exacerbate species extinction and challenge the Kunming-Montreal Global Biodiversity Framework(GBF).This study delves into the human disturbance and protection in terrestrial KBAs worldwide,focusing particularly on habitat fragmentation to devise tailored conservation strategies.Our results reveal widespread human disturbance across global KBAs,with an average Human Footprint Index of 12.3 and a disturbance rate of 62%.Only one-fifth of KBAs are fully safeguarded by protected areas,and a significant portion remains unprotected,with even many highly protected sites under severe disturbance.Globally,human activities have led to substantial implicit habitat fragmentation in KBAs,resulting in a 70%average decline in habitat size,with less than half of KBAs maintaining well-connected active habitats.These findings inform the classification of KBAs for priority conservation,with 80%requiring both intensity regulation and spatial planning of human activities.Higher levels of human disturbance do not necessarily lead to more severe fragmentation,underscoring the potential for relocating or planning human activities to mitigate fragmentation.This research serves as a foundational assessment of human impacts on KBAs,providing a basis for KBA management and global conservation efforts to meet GBF goals.展开更多
Filler-reinforced polymer composites demonstrate pervasive applications due to their strengthened performances,multi-degree tunability,and ease of manufacturing.In thermal management field,polymer composites reinforce...Filler-reinforced polymer composites demonstrate pervasive applications due to their strengthened performances,multi-degree tunability,and ease of manufacturing.In thermal management field,polymer composites reinforced with thermally conductive fillers are widely adopted as thermal interface materials(TIMs).However,the three dimensional(3D)-stacked heterogenous integration of electronic devices has posed the problem that high-density heat sources are spatially distributed in the package.This situation puts forward new requirements for TIMs,where efficient heat dissipation channels must be established according to the specific distribution of discrete heat sources.To address this challenge,a 3D printing-assisted streamline orientation(3D-PSO)method was proposed to fabricate composite thermal materials with 3D programmable microstructures and orientations of fillers,which combines the shape-design capability of 3D printing and oriented control ability of fluid.The mechanism of fluid-based filler orientation control along streamlines was revealed by mechanical analysis of fillers in matrix.Thanks to the designed heat dissipation channels,composites showed better thermal and mechanical properties in comparison to random composites.Specifically,the thermal conductivity of 3D mesh-shape polydimethylsiloxane/liquid metal(PDMS/LM)composite was5.8 times that of random PDMS/LM composite under filler loading of 34.8 vol%.The thermal conductivity enhancement efficiency of 3D mesh-shape PDMS/carbon fibers composite reached101.05%under filler loading of 5.2 vol%.In the heat dissipation application of 3D-stacked chips,the highest chip temperature with 3D-PSO composite was 42.14℃lower than that with random composites.This is mainly attributed to the locally aggregated and oriented fillers'microstructure in fluid channels,which contributes to thermal percolation phenomena.The3D-PSO method exhibits excellent programmable design capabilities to adopt versatile distributions of heat sources,paving a new way to solve the complicated heat dissipation issue in 3D-stacked chips integration application.展开更多
China boasts over 10,000 native useful vascular plants(NUVPs),spanning eight families and serving twelve dis-tinct uses.Given the importance of NUVPs,widely-confirmed in-situ conservation policies,such as establishing...China boasts over 10,000 native useful vascular plants(NUVPs),spanning eight families and serving twelve dis-tinct uses.Given the importance of NUVPs,widely-confirmed in-situ conservation policies,such as establishing nature reserves,have been broadly implemented to protect them.However,the effectiveness of in-situ conser-vation efforts for NUVPs in China remains uncertain.Highlighting the importance of multi-family and multi-use plants,this research identified the spatial distribution pattern and diversity hotspots of NUVPs,evaluated the in-situ conservation effectiveness and provided the future conservation priority scheme.The results revealed that the spatial concentration of NUVPs is predominantly in the southwestern lowlands of China(<3,000 m),peaking around 109°E and 25°N.Importantly,diversity hotspots exhibited a significant spatial mismatch(over 80%)with the National Nature Reserve(NNR)network.Only about 17.7%and 13.3%of these hotspots are protected by NNR initiatives for endemic and nonendemic species,respectively.Additionally,the proposed Plants Conserva-tion Effectiveness Index(PCEI)proved more representative in addressing the two main crises faced by the studied species-species loss and human pressure,and found a decline in conservation effectiveness as the number of uses increased.Finally,future conservation priorities based on the PCEI highlight the Nanling Mountains,Heng-duan Mountains,Jiuwandashan,and Qilian Mountains as highly prioritized regions requiring focused efforts to address the impacts of climate change.Conversely,in sparsely distributed regions experiencing increasing human pressure,it is imperative to mitigate the expanding human footprint.展开更多
The implementation of the ecological protection red line serves as a crucial protective barrier for the conservation of wild plants with extremely small populations by delineating specific geographical areas designate...The implementation of the ecological protection red line serves as a crucial protective barrier for the conservation of wild plants with extremely small populations by delineating specific geographical areas designated for their conservation.The implementation of a comprehensive set of conservation measures aimed at establishing a biodiversity conservation network for wild plants with extremely small populations has laid the foundation for the health and stability of ecosystems,as well as the harmonious coexistence of humans and the natural environment.Research on the conservation of wild plants with extremely small populations serves as a critical foundation for informing and enhancing the effective conservation of such populations.This paper provides a systematic examination of the theoretical and practical conservation status of certain wild plants with extremely small populations and discusses the conservation trends of these populations within the framework of ecological protection red line delineation.In the future,strategies for the conservation of wild plants with extremely small populations should be integrated with an analysis of the causes of endangerment.This approach will provide a robust foundation for applied research focused on the conservation of these vulnerable plant populations.展开更多
With the development of our country’s social economy,the construction scale of water conservancy project has had an obvious expansion.In the construction of water conservancy projects,certain impacts on the surroundi...With the development of our country’s social economy,the construction scale of water conservancy project has had an obvious expansion.In the construction of water conservancy projects,certain impacts on the surrounding water and soil conditions are inevitable.These impacts may lead to problems such as soil erosion,which can directly affect local production,livelihoods,and the natural ecological environment on which people depend.In severe cases,such issues may even hinder the progress and quality of the water conservancy project itself.Therefore,in the construction of water conservancy projects,soil and water conservation work is extremely important.Based on this,this paper mainly aimed at the prevention and control of water and soil conservation of water conservancy projects launched the relevant analysis and research.展开更多
1.Need for coordinated flyways conservation Flyways are migratory routes that encompass breeding,stopover,and non-breeding habitats essential for the annual life cycles of migratory birds(Bamford et al.,2008;Newton,20...1.Need for coordinated flyways conservation Flyways are migratory routes that encompass breeding,stopover,and non-breeding habitats essential for the annual life cycles of migratory birds(Bamford et al.,2008;Newton,2023).These routes are critical for maintaining global biodiversity by supporting seasonal movements across continents(Hua et al.,2015;Runge et al.,2015).Effective conservation of flyways,such as the East Asian-Australasian Flyway(EAAF)and Central Asian Flyway(CAF),requires international cooperation to protect key stopover sites(Yong et al.,2015;Kumar 2019;Schmaljohann et al.,2022).展开更多
1.Introduction As global temperatures increase and weather patterns grow more er-ratic,the urgency of adopting climate-smart conservation strategies has intensified(Manyakaidze et al.,2024).Climate-smart conservation ...1.Introduction As global temperatures increase and weather patterns grow more er-ratic,the urgency of adopting climate-smart conservation strategies has intensified(Manyakaidze et al.,2024).Climate-smart conservation com-prises adaptive management practices aimed at bolstering the resilience of ecosystems and species amid climate variability(Birchall et al.,2021;Gabriel-Campos et al.,2021).展开更多
As the integration of electronic components in high-performance servers increases,heat generation significantly impacts performance and raises failure rates.Therefore,heat dissipation has become a critical concern in ...As the integration of electronic components in high-performance servers increases,heat generation significantly impacts performance and raises failure rates.Therefore,heat dissipation has become a critical concern in electronic circuit design.This study uses numerical simulations to investigate the heat dissipation characteristics of electronic components in air-cooled servers.By adjusting airflow speed,heat sink configurations,and the arrangement of straight-fin heat sinks,we optimize heat dissipation performance and analyze the mechanisms at different airflow speeds.The results show that,at the same airflow speed,the temperature of the heat sink is lower than that of the electronic components,creating a temperature gradient that enhances heat transfer.Compared to a front-to-back arrangement of two straight-fin heat sinks,placing the heat sinks parallel to each other results in a lower maximum component temperature and better temperature uniformity.Heat sinks with fins significantly improve heat dissipation.The heat sink with semicylindrical fins on the rib surface provides the best cooling performance.Moreover,compared to natural convection,the maximum temperature of the electronic components decreases by 56.17%and 61%when the incoming flow velocity is 6 m/s with two parallel flat ribbed heat sinks and front-to-back arrangement,respectively.展开更多
Heat and mass transfer during the process of liquid droplet dynamic behaviors has attracted much attention in decades.At mesoscopic scale,numerical simulations of liquid droplets motion,such as impacting,sliding,and c...Heat and mass transfer during the process of liquid droplet dynamic behaviors has attracted much attention in decades.At mesoscopic scale,numerical simulations of liquid droplets motion,such as impacting,sliding,and coalescence,have been widely studied by using the particle-based method named many-body dissipative particle dynamics(MDPD).However,the detailed information on heat transfer needs further description.This paper develops a modified MDPD with energy conservation(MDPDE)by introducing a temperature-dependent long-term attractive interaction.By fitting or deriving the expressions of the strength of the attractive force,the exponent of the weight function in the dissipative force,and the mesoscopic heat friction coefficient about temperature,we calculate the viscosity,self-diffusivity,thermal conductivity,and surface tension,and obtain the Schmidt number Sc,the Prandtl number P r,and the Ohnesorge number Oh for 273 K to 373 K.The simulation data of MDPDE coincide well with the experimental data of water,indicating that our model can be used to simulate the dynamic behaviors of liquid water.Furthermore,we compare the equilibrium contact angle of droplets wetting on solid surfaces with that calculated from three interfacial tensions by MDPDE simulations.The coincident results not only stand for the validation of Young’s equation at mesoscale,but manifest the reliability of our MDPDE model and applicability to the cases with free surfaces.Our model can be extended to study the multiphase flow withcomplex heat and mass transfer.展开更多
After excavation,some of the surrounding rock mass is in a state of triaxial extension,exhibiting tensile or shear fracture modes.To study the energy mechanism of tensile fracture turning to shear fracture,a series of...After excavation,some of the surrounding rock mass is in a state of triaxial extension,exhibiting tensile or shear fracture modes.To study the energy mechanism of tensile fracture turning to shear fracture,a series of triaxial extension tests were conducted on sandstone under confining pressures of 10,30,50 and 70 MPa.Elastic energy and dissipated energy were separated by single unloading,the input energy u_(t),elastic energy u_(e),and dissipated energy u_(d)at different unloading stress levels were calculated by the integrating stress−strain curves.The results show that tensile cracks dominate fracture under lower confining pressure(10 MPa),and shear cracks play an increasingly important role in fracture as confining pressure increases(30,50 and 70 MPa).Based on the phenomenon that u_(e)and u_(d)increase linearly with increasing u_(t),a possible energy distribution mechanism of fracture mode transition under triaxial extension was proposed.In addition,it was found that peak energy storage capacity is more sensitive to confining pressure compared to elastic energy conversion capacity.展开更多
Stress accumulation is a key factor leading to sodium storage performance deterioration for NiSe_(2)-based anodes.Therefore,inhibiting the concentrated local stress during the sodiataion/desodiation process is crucial...Stress accumulation is a key factor leading to sodium storage performance deterioration for NiSe_(2)-based anodes.Therefore,inhibiting the concentrated local stress during the sodiataion/desodiation process is crucial for acquiring stable NiSe2-based materials for sodium-ion batteries(SIBs),Herein,a stress dissipation strategy driven by architecture engineering is proposed,which can achieve ultrafast and ultralong sodium storage properties.Different from the conventional sphere-like or rod-like architecture,the three-dimensional(3D)flower-like NiSe_(2)@C composite is delicately designed and assembled with onedimensional nanorods and carbon framework.More importantly,the fundamental mechanism of improved structure stability is unveiled by simulations and experimental results simultaneously.It demonstrates that this designed multidimensional flower-like architecture with dispersed nanorods can balance the structural mismatch,avoid concentrated local strain,and relax the internal stress,mainly induced by the unavoidable volume variation during the repeated conversion processes.Moreover,it can provide more Na^(+)-storage sites and multi-directional migration pathways,leading to a fast Na^(+)-migration channel with boosted reaction kinetic.As expected,it delivers superior rate performance(441 mA h g^(-1)at 5.0 A g^(-1))and long cycling stability(563 mA h g^(-1)at 1.0 A g^(-1)over 1000 cycles)for SIBs.This work provides useful insights for designing high-performance conversion-based anode materials for SIBs.展开更多
The combination of advanced photoelectric detectors has rendered single-band camouflage materials ineffective,necessitating the development of infrared multispectral camouflage.However,the design and fabrication of ex...The combination of advanced photoelectric detectors has rendered single-band camouflage materials ineffective,necessitating the development of infrared multispectral camouflage.However,the design and fabrication of existing works remain complex as they usually require the integration of multiscale structures.Here,we introduce phase modulation into the infrared camouflage metasurfaces with metal-dielectric-metal configuration,enabling them to achieve camouflage across more bands.Based on this strategy,a simple but effective single-layer cascaded metasurface is demonstrated for the first time to achieve low reflection at multi-wavelength lasers,low infrared radiation in atmospheric windows,and broadband thermal management.As a proof-of-concept,a 4-inch sample with a minimum linewidth of 1.8μm is fabricated using photolithography.The excellent infrared multispectral camouflage performance is verified in experiments,showing low reflectance in 0.9–1.6μm,low infrared emissivity in mid-wavelength infrared(MWIR)and long-wavelength infrared(LWIR)bands,and high absorptance at the wavelength of 10.6μm.Meanwhile,broadband high emissivity in 5–8μm can provide high-performance radiative heat dissipation.When the input power is 1.57 W·cm^(-2),the surface/radiation temperature of the metasurface decreases by 5.3℃/18.7℃ compared to the reference.The proposed metasurface may trigger further innovation in the design and application of compact multispectral optical devices.展开更多
As living standards improve,the energy consumption for regulating indoor temperature keeps increasing.Windows,in particular,enhance indoor brightness but also lead to increased energy loss,especially in sunny weather....As living standards improve,the energy consumption for regulating indoor temperature keeps increasing.Windows,in particular,enhance indoor brightness but also lead to increased energy loss,especially in sunny weather.Developing a product that can maintain indoor brightness while reducing energy consumption is a challenge.We developed a facile,spectrally selective transparent ultrahigh-molecular-weight polyethylene composite film to address this trade-off.It is based on a blend of antimony-doped tin oxide and then spin-coated hydrophobic fumed silica,achieving a high visible light transmittance(>70%)and high shielding rates for ultraviolet(>90%)and near-infrared(>70%).When applied to the acrylic window of containers and placed outside,this film can cause a 10℃ temperature drop compared to a pure polymer film.Moreover,in building energy simulations,the annual energy savings could be between 14.1%~31.9%per year.The development of energy-efficient and eco-friendly transparent films is crucial for reducing energy consumption and promoting sustainability in the window environment.展开更多
The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissip...The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissipation(LED)law,a novel compressive damage constitutive model for brittle coal is proposed.Utilizing the energy-defined damage method for mate-rials,the LED law is innovatively introduced to accurately characterize the energy dissipation during the loading process,and a novel formula for characterizing the damage variable of brittle coal is proposed.On this basis,considering that the constitutive model based on the hypothesis of strain equivalence is incapable of accurately describing the compaction effect exhibited by coal material during the compression process,a correction coefficient is proposed and apply it in the novel damage constitutive model.The established conventional monotone loading and single-cyclic loading-unloading uniaxial compression damage constitutive models have been validated using experimental data from cylindrical and cuboid coal specimens.In addition,compared with the constitutive model obtained via the traditional energy calculation method based on the hypothesis that the unloading curve is a straight line,the constitutive model employing LED law can describe the stress-strain state of brittle coal more precisely.This approach introduces a new perspective and enhances the convenience for constructing the constitutive model based on energy theory.展开更多
The method of integrating factors is used to study the conservation laws of the Herglotz type Birkhoffian systems in this paper.Firstly,the definition of the integrating factors of the Herglotz type Birkhoffian system...The method of integrating factors is used to study the conservation laws of the Herglotz type Birkhoffian systems in this paper.Firstly,the definition of the integrating factors of the Herglotz type Birkhoffian systems is given.Secondly,the relationship between the integrating factors and conservation laws is studied,and the conservation theorems of Herglotz type Birkhoff's equations and their inverse theorems are established.Thirdly,two types of generalized Killing equations for calculating integrating factors are given.Finally,as an example,a linear damped oscillator is taken.This example can be transformed into a Herglotz type Birkhoffian system.The resulting conservation theorems are used to find the conserved quantities for this example.展开更多
基金supported by the Natural Science Research Project of the Anhui Educational Committee,China(No.2022AH050827)the Open Research Fund Program of Anhui Province Key Laboratory of Specialty Polymers,Anhui University of Science and Technology,China(No.AHKLSP23-12)the Joint National-Local Engineering Research Center for Safe and Precise Coal Mining Fund,China(No.EC2022020)。
文摘The preparation of carbon-based electromagnetic wave(EMW)absorbers possessing thin matching thickness,wide absorption bandwidth,strong absorption intensity,and low filling ratio remains a huge challenge.Metal-organic frameworks(MOFs)are ideal self-sacrificing templates for the construction of carbon-based EMW absorbers.In this work,bimetallic FeMn-MOF-derived MnFe_(2)O_(4)/C/graphene composites were fabricated via a two-step route of solvothermal reaction and the following pyrolysis treatment.The results re-veal the evolution of the microscopic morphology of carbon skeletons from loofah-like to octahedral and then to polyhedron and pomegran-ate after the adjustment of the Fe^(3+)to Mn^(2+)molar ratio.Furthermore,at the Fe^(3+)to Mn^(2+)molar ratio of 2:1,the obtained MnFe_(2)O_(4)/C/graphene composite exhibited the highest EMW absorption capacity.Specifically,a minimum reflection loss of-72.7 dB and a max-imum effective absorption bandwidth of 5.1 GHz were achieved at a low filling ratio of 10wt%.In addition,the possible EMW absorp-tion mechanism of MnFe_(2)O_(4)/C/graphene composites was proposed.Therefore,the results of this work will contribute to the construction of broadband and efficient carbon-based EMW absorbers derived from MOFs.
基金supported by the Lebanese International University(LIU)with a funding amount of$500.
文摘Ecological conservation is at a crossroad as environmental stresses around the world intensify and traditional models of conservation exhibit intrinsic weaknesses in their response to present and future problems.In the project,we evaluated novel approaches integrating adaptive management,technological innovations,and community-based action towards more efficient sustainable conservation results and ecosystem resilience.The multi-site experimental design was based on comparison between conventional reserve management and novel integrative models implemented in diverse ecological zones.Data were collected over a period of three years employing remote sensing technologies,in situ biodiversity assessments,and large socioeconomic surveys.These instruments enabled a robust and multi-dimensional measurement of variables such as species diversity,ecological resilience,community engagement,and stakeholder engagement.The results indicate that adaptive strategies significantly enhance real-time decision-making abilities and enhance long-term ecosystem resilience.Further,technology-driven monitoring greatly enhances data accuracy,responsiveness,and early warning capabilities.Besides that,community-based conservation initiatives were found to be pivotal in facilitating local stewardship,enhancing participatory governance,and enabling more adaptive and adaptive policy systems.This research rejects mainstream conservation paradigms by placing importance on flexibility,interdisciplinarity,and inclusivity of governance systems in effectively mitigating the impacts of climate change and loss of biodiversity.Our findings offer strong evidence that emerging paradigms of conservation can provide greater ecological and social sustainability than traditional methods.These results support the need for a paradigm shift towards conservation strategies that are dynamic,collaborative,and technologically integrated,with significant implications for policy formulation as well as operational environmental management.
文摘This paper presents both analytical and numerical studies of the conservative Sawada-Kotera equation and its dissipative generalization,equations known for their soliton solutions and rich chaotic dynamics.These models offer valuable insights into nonlinear wave propagation,with applications in fluid dynamics and materials science,including systems such as liquid crystals and ferrofluids.It is shown that the conservative Sawada-Kotera equation supports traveling wave solutions corresponding to elliptic limit cycles,as well as two-and three-dimensional invariant tori surrounding these cycles in the associated ordinary differential equation(ODE)system.For the dissipative generalized Sawada-Kotera equation,chaotic wave behavior is observed.The transition to chaos in the corresponding ODE systemfollows a universal bifurcation scenario consistent with the framework established by FShM(Feigenbaum-Sharkovsky-Magnitskii)theory.Notably,this study demonstrates for the first time that the conservative Sawada-Kotera equation can exhibit complex quasi-periodic wave solutions,while its dissipative counterpart admits an infinite number of stable periodic and chaotic waveforms.
文摘This work focuses on a Keller-Segel chemotaxis model, with an emphasis on its conservation laws. Through a new approach combined with the multiplier method, called the mixed method, we obtain conservation vectors that are related and unrelated to symmetric information. In addition, some exact solutions with particular forms are obtained according to the method of conservation laws. These particular solutions are different from the group-invariant solutions.
基金supported by the Ministry of Science and Technology of China(Grant No.2022YFF1301500)the National Natural Science Foun-dation of China(Grants No.32000352,32171485,and 32371741)+1 种基金the Natural Science Foundation of Guangdong Province(Grant No.2021A1515010968)Fundamental Research Funds for the Central Universities,Sun Yat-sen University(Grant No.23lgzy002).
文摘Disaster risk reduction,an essential function of protected areas(PAs),has been generally overlooked in PA design.Using primates as a model,we designed a disaster risk index(DRI)to measure the disaster sensitivity of primate species.High-conservation-need(HCN)areas were identified by both their richness and number of threatened primate species.We also constructed high-disaster-risk(HDR)areas and climate-sensitive(CS)areas based on a disaster risk assessment and temperature change under climate change.We overlaid HCN and HDR areas to obtain HDR-HCN areas.We defined species conservation targets as the percent of each species’range that should be effectively conserved using“Zonation”.Landslides had the highest DRI(1.43±0.88),but have been overlooked in previous studies.PA coverage in HDR-HCN(30%)areas was similar to that in HCN areas(28%),indicating that current PA design fails to account for disaster risk reduction.About 50%of the HDR-HCN areas overlapped with CS areas.Presently,43%of primate species meet their conservation targets.Fifty-seven of primate species would meet their conservation targets and 67%of primates could benefit from PA expansion if HDR-HCN areas are fully incorporated into PAs.Increasing PA coverage in HDR-HCN areas is essential to achieving both primate conservation and disaster risk reduction.The study calls for integrating disaster risk reduction into PA design guidelines,particularly in regions like the western Amazon,and recommends flexible conservation approaches in other areas.
基金supported by the National Key Research and De-velopment Program(Grant No.2023YFE0122300)the Hunan Provin-cial Natural Science Foundation of China(Grant No.2024JJ8351)the Fundamental Research Funds for the Central Universities(Grant No.S20230127).
文摘Effective preservation of Key Biodiversity Areas(KBAs)is crucial to address biodiversity loss.Human-induced disturbance in these vital sites can exacerbate species extinction and challenge the Kunming-Montreal Global Biodiversity Framework(GBF).This study delves into the human disturbance and protection in terrestrial KBAs worldwide,focusing particularly on habitat fragmentation to devise tailored conservation strategies.Our results reveal widespread human disturbance across global KBAs,with an average Human Footprint Index of 12.3 and a disturbance rate of 62%.Only one-fifth of KBAs are fully safeguarded by protected areas,and a significant portion remains unprotected,with even many highly protected sites under severe disturbance.Globally,human activities have led to substantial implicit habitat fragmentation in KBAs,resulting in a 70%average decline in habitat size,with less than half of KBAs maintaining well-connected active habitats.These findings inform the classification of KBAs for priority conservation,with 80%requiring both intensity regulation and spatial planning of human activities.Higher levels of human disturbance do not necessarily lead to more severe fragmentation,underscoring the potential for relocating or planning human activities to mitigate fragmentation.This research serves as a foundational assessment of human impacts on KBAs,providing a basis for KBA management and global conservation efforts to meet GBF goals.
基金supported by the National Natural Science Foundation of China(Grant No.52106089)the National Key R&D Project from Ministry of Science and Technology of China(Grant No.2022YFA1203100)。
文摘Filler-reinforced polymer composites demonstrate pervasive applications due to their strengthened performances,multi-degree tunability,and ease of manufacturing.In thermal management field,polymer composites reinforced with thermally conductive fillers are widely adopted as thermal interface materials(TIMs).However,the three dimensional(3D)-stacked heterogenous integration of electronic devices has posed the problem that high-density heat sources are spatially distributed in the package.This situation puts forward new requirements for TIMs,where efficient heat dissipation channels must be established according to the specific distribution of discrete heat sources.To address this challenge,a 3D printing-assisted streamline orientation(3D-PSO)method was proposed to fabricate composite thermal materials with 3D programmable microstructures and orientations of fillers,which combines the shape-design capability of 3D printing and oriented control ability of fluid.The mechanism of fluid-based filler orientation control along streamlines was revealed by mechanical analysis of fillers in matrix.Thanks to the designed heat dissipation channels,composites showed better thermal and mechanical properties in comparison to random composites.Specifically,the thermal conductivity of 3D mesh-shape polydimethylsiloxane/liquid metal(PDMS/LM)composite was5.8 times that of random PDMS/LM composite under filler loading of 34.8 vol%.The thermal conductivity enhancement efficiency of 3D mesh-shape PDMS/carbon fibers composite reached101.05%under filler loading of 5.2 vol%.In the heat dissipation application of 3D-stacked chips,the highest chip temperature with 3D-PSO composite was 42.14℃lower than that with random composites.This is mainly attributed to the locally aggregated and oriented fillers'microstructure in fluid channels,which contributes to thermal percolation phenomena.The3D-PSO method exhibits excellent programmable design capabilities to adopt versatile distributions of heat sources,paving a new way to solve the complicated heat dissipation issue in 3D-stacked chips integration application.
基金supported by the National Natural Science Foundation of China(Grant No.42330205)the Open Fund of State Key Labora-tory of Remote Sensing Science and Beijing Engineering Research Center for Global Land Remote Sensing Products(Grant No.OF202206).
文摘China boasts over 10,000 native useful vascular plants(NUVPs),spanning eight families and serving twelve dis-tinct uses.Given the importance of NUVPs,widely-confirmed in-situ conservation policies,such as establishing nature reserves,have been broadly implemented to protect them.However,the effectiveness of in-situ conser-vation efforts for NUVPs in China remains uncertain.Highlighting the importance of multi-family and multi-use plants,this research identified the spatial distribution pattern and diversity hotspots of NUVPs,evaluated the in-situ conservation effectiveness and provided the future conservation priority scheme.The results revealed that the spatial concentration of NUVPs is predominantly in the southwestern lowlands of China(<3,000 m),peaking around 109°E and 25°N.Importantly,diversity hotspots exhibited a significant spatial mismatch(over 80%)with the National Nature Reserve(NNR)network.Only about 17.7%and 13.3%of these hotspots are protected by NNR initiatives for endemic and nonendemic species,respectively.Additionally,the proposed Plants Conserva-tion Effectiveness Index(PCEI)proved more representative in addressing the two main crises faced by the studied species-species loss and human pressure,and found a decline in conservation effectiveness as the number of uses increased.Finally,future conservation priorities based on the PCEI highlight the Nanling Mountains,Heng-duan Mountains,Jiuwandashan,and Qilian Mountains as highly prioritized regions requiring focused efforts to address the impacts of climate change.Conversely,in sparsely distributed regions experiencing increasing human pressure,it is imperative to mitigate the expanding human footprint.
基金Supported by 2024 Central Financial Comprehensive Protection Project for Abies chensiensis(610000242000000026647)2024 Provincial Forestry and Grassland Reform and Development Fund for the National Key Wild Plant Protection Project(610000242000000028574)2024 Biodiversity Conservation Project(610000242000000024911).
文摘The implementation of the ecological protection red line serves as a crucial protective barrier for the conservation of wild plants with extremely small populations by delineating specific geographical areas designated for their conservation.The implementation of a comprehensive set of conservation measures aimed at establishing a biodiversity conservation network for wild plants with extremely small populations has laid the foundation for the health and stability of ecosystems,as well as the harmonious coexistence of humans and the natural environment.Research on the conservation of wild plants with extremely small populations serves as a critical foundation for informing and enhancing the effective conservation of such populations.This paper provides a systematic examination of the theoretical and practical conservation status of certain wild plants with extremely small populations and discusses the conservation trends of these populations within the framework of ecological protection red line delineation.In the future,strategies for the conservation of wild plants with extremely small populations should be integrated with an analysis of the causes of endangerment.This approach will provide a robust foundation for applied research focused on the conservation of these vulnerable plant populations.
文摘With the development of our country’s social economy,the construction scale of water conservancy project has had an obvious expansion.In the construction of water conservancy projects,certain impacts on the surrounding water and soil conditions are inevitable.These impacts may lead to problems such as soil erosion,which can directly affect local production,livelihoods,and the natural ecological environment on which people depend.In severe cases,such issues may even hinder the progress and quality of the water conservancy project itself.Therefore,in the construction of water conservancy projects,soil and water conservation work is extremely important.Based on this,this paper mainly aimed at the prevention and control of water and soil conservation of water conservancy projects launched the relevant analysis and research.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(RS-2021-NR060142)HSF's GMACC Project。
文摘1.Need for coordinated flyways conservation Flyways are migratory routes that encompass breeding,stopover,and non-breeding habitats essential for the annual life cycles of migratory birds(Bamford et al.,2008;Newton,2023).These routes are critical for maintaining global biodiversity by supporting seasonal movements across continents(Hua et al.,2015;Runge et al.,2015).Effective conservation of flyways,such as the East Asian-Australasian Flyway(EAAF)and Central Asian Flyway(CAF),requires international cooperation to protect key stopover sites(Yong et al.,2015;Kumar 2019;Schmaljohann et al.,2022).
文摘1.Introduction As global temperatures increase and weather patterns grow more er-ratic,the urgency of adopting climate-smart conservation strategies has intensified(Manyakaidze et al.,2024).Climate-smart conservation com-prises adaptive management practices aimed at bolstering the resilience of ecosystems and species amid climate variability(Birchall et al.,2021;Gabriel-Campos et al.,2021).
基金supported by the key technology project of China Southern Power Grid Corporation(GZKJXM20240009).
文摘As the integration of electronic components in high-performance servers increases,heat generation significantly impacts performance and raises failure rates.Therefore,heat dissipation has become a critical concern in electronic circuit design.This study uses numerical simulations to investigate the heat dissipation characteristics of electronic components in air-cooled servers.By adjusting airflow speed,heat sink configurations,and the arrangement of straight-fin heat sinks,we optimize heat dissipation performance and analyze the mechanisms at different airflow speeds.The results show that,at the same airflow speed,the temperature of the heat sink is lower than that of the electronic components,creating a temperature gradient that enhances heat transfer.Compared to a front-to-back arrangement of two straight-fin heat sinks,placing the heat sinks parallel to each other results in a lower maximum component temperature and better temperature uniformity.Heat sinks with fins significantly improve heat dissipation.The heat sink with semicylindrical fins on the rib surface provides the best cooling performance.Moreover,compared to natural convection,the maximum temperature of the electronic components decreases by 56.17%and 61%when the incoming flow velocity is 6 m/s with two parallel flat ribbed heat sinks and front-to-back arrangement,respectively.
基金Project supported by the National Natural Science Foundation of China(Nos.11872283,12002242,11902188,and 12102218)the Shanghai Science and Technology Talent Program(No.19YF1417400)the China Postdoctoral Science Foundation(No.2020M680525)。
文摘Heat and mass transfer during the process of liquid droplet dynamic behaviors has attracted much attention in decades.At mesoscopic scale,numerical simulations of liquid droplets motion,such as impacting,sliding,and coalescence,have been widely studied by using the particle-based method named many-body dissipative particle dynamics(MDPD).However,the detailed information on heat transfer needs further description.This paper develops a modified MDPD with energy conservation(MDPDE)by introducing a temperature-dependent long-term attractive interaction.By fitting or deriving the expressions of the strength of the attractive force,the exponent of the weight function in the dissipative force,and the mesoscopic heat friction coefficient about temperature,we calculate the viscosity,self-diffusivity,thermal conductivity,and surface tension,and obtain the Schmidt number Sc,the Prandtl number P r,and the Ohnesorge number Oh for 273 K to 373 K.The simulation data of MDPDE coincide well with the experimental data of water,indicating that our model can be used to simulate the dynamic behaviors of liquid water.Furthermore,we compare the equilibrium contact angle of droplets wetting on solid surfaces with that calculated from three interfacial tensions by MDPDE simulations.The coincident results not only stand for the validation of Young’s equation at mesoscale,but manifest the reliability of our MDPDE model and applicability to the cases with free surfaces.Our model can be extended to study the multiphase flow withcomplex heat and mass transfer.
基金Project(52074352)supported by the National Natural Science Foundation of ChinaProject(2023JJ30680)supported by the National Science and Technology Major Project of China。
文摘After excavation,some of the surrounding rock mass is in a state of triaxial extension,exhibiting tensile or shear fracture modes.To study the energy mechanism of tensile fracture turning to shear fracture,a series of triaxial extension tests were conducted on sandstone under confining pressures of 10,30,50 and 70 MPa.Elastic energy and dissipated energy were separated by single unloading,the input energy u_(t),elastic energy u_(e),and dissipated energy u_(d)at different unloading stress levels were calculated by the integrating stress−strain curves.The results show that tensile cracks dominate fracture under lower confining pressure(10 MPa),and shear cracks play an increasingly important role in fracture as confining pressure increases(30,50 and 70 MPa).Based on the phenomenon that u_(e)and u_(d)increase linearly with increasing u_(t),a possible energy distribution mechanism of fracture mode transition under triaxial extension was proposed.In addition,it was found that peak energy storage capacity is more sensitive to confining pressure compared to elastic energy conversion capacity.
基金the financial support from the Guangxi Natural Science Foundation(grant no.2021GXNSFDA075012,2023GXNSFGA026002)National Natural Science Foundation of China(52104298,22075073,52362027,52462029)Fundamental Research Funds for the Central Universities(531107051077).
文摘Stress accumulation is a key factor leading to sodium storage performance deterioration for NiSe_(2)-based anodes.Therefore,inhibiting the concentrated local stress during the sodiataion/desodiation process is crucial for acquiring stable NiSe2-based materials for sodium-ion batteries(SIBs),Herein,a stress dissipation strategy driven by architecture engineering is proposed,which can achieve ultrafast and ultralong sodium storage properties.Different from the conventional sphere-like or rod-like architecture,the three-dimensional(3D)flower-like NiSe_(2)@C composite is delicately designed and assembled with onedimensional nanorods and carbon framework.More importantly,the fundamental mechanism of improved structure stability is unveiled by simulations and experimental results simultaneously.It demonstrates that this designed multidimensional flower-like architecture with dispersed nanorods can balance the structural mismatch,avoid concentrated local strain,and relax the internal stress,mainly induced by the unavoidable volume variation during the repeated conversion processes.Moreover,it can provide more Na^(+)-storage sites and multi-directional migration pathways,leading to a fast Na^(+)-migration channel with boosted reaction kinetic.As expected,it delivers superior rate performance(441 mA h g^(-1)at 5.0 A g^(-1))and long cycling stability(563 mA h g^(-1)at 1.0 A g^(-1)over 1000 cycles)for SIBs.This work provides useful insights for designing high-performance conversion-based anode materials for SIBs.
基金financial supports from the National Natural Science Foundation of China(Grant Nos.51925503&52105575)the Fundamental Research Funds for the Central Universities(Grant No.QTZX23063)+2 种基金the Aeronautical Science Foundation of China(Grant No.2022Z073081001)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20232028)the Open Research Funds of State Key Laboratory of Intelligent Manufacturing Equipment and Technology(Grant No.IMETKF2024008).
文摘The combination of advanced photoelectric detectors has rendered single-band camouflage materials ineffective,necessitating the development of infrared multispectral camouflage.However,the design and fabrication of existing works remain complex as they usually require the integration of multiscale structures.Here,we introduce phase modulation into the infrared camouflage metasurfaces with metal-dielectric-metal configuration,enabling them to achieve camouflage across more bands.Based on this strategy,a simple but effective single-layer cascaded metasurface is demonstrated for the first time to achieve low reflection at multi-wavelength lasers,low infrared radiation in atmospheric windows,and broadband thermal management.As a proof-of-concept,a 4-inch sample with a minimum linewidth of 1.8μm is fabricated using photolithography.The excellent infrared multispectral camouflage performance is verified in experiments,showing low reflectance in 0.9–1.6μm,low infrared emissivity in mid-wavelength infrared(MWIR)and long-wavelength infrared(LWIR)bands,and high absorptance at the wavelength of 10.6μm.Meanwhile,broadband high emissivity in 5–8μm can provide high-performance radiative heat dissipation.When the input power is 1.57 W·cm^(-2),the surface/radiation temperature of the metasurface decreases by 5.3℃/18.7℃ compared to the reference.The proposed metasurface may trigger further innovation in the design and application of compact multispectral optical devices.
基金financially supported by the Natural Science Foundation of Henan(242300421010)National Natural Science Foundation of China(52403055).
文摘As living standards improve,the energy consumption for regulating indoor temperature keeps increasing.Windows,in particular,enhance indoor brightness but also lead to increased energy loss,especially in sunny weather.Developing a product that can maintain indoor brightness while reducing energy consumption is a challenge.We developed a facile,spectrally selective transparent ultrahigh-molecular-weight polyethylene composite film to address this trade-off.It is based on a blend of antimony-doped tin oxide and then spin-coated hydrophobic fumed silica,achieving a high visible light transmittance(>70%)and high shielding rates for ultraviolet(>90%)and near-infrared(>70%).When applied to the acrylic window of containers and placed outside,this film can cause a 10℃ temperature drop compared to a pure polymer film.Moreover,in building energy simulations,the annual energy savings could be between 14.1%~31.9%per year.The development of energy-efficient and eco-friendly transparent films is crucial for reducing energy consumption and promoting sustainability in the window environment.
基金supported by the National Science Fund for Distinguished Young Scholars(52225403)the National Natural Science Foundation of China(42077244).
文摘The study of the mechanical property and damage state of coal materials under compression is a fundamental area of research in underground mining engineering.Drawing upon the compaction effect and linear energy dissipation(LED)law,a novel compressive damage constitutive model for brittle coal is proposed.Utilizing the energy-defined damage method for mate-rials,the LED law is innovatively introduced to accurately characterize the energy dissipation during the loading process,and a novel formula for characterizing the damage variable of brittle coal is proposed.On this basis,considering that the constitutive model based on the hypothesis of strain equivalence is incapable of accurately describing the compaction effect exhibited by coal material during the compression process,a correction coefficient is proposed and apply it in the novel damage constitutive model.The established conventional monotone loading and single-cyclic loading-unloading uniaxial compression damage constitutive models have been validated using experimental data from cylindrical and cuboid coal specimens.In addition,compared with the constitutive model obtained via the traditional energy calculation method based on the hypothesis that the unloading curve is a straight line,the constitutive model employing LED law can describe the stress-strain state of brittle coal more precisely.This approach introduces a new perspective and enhances the convenience for constructing the constitutive model based on energy theory.
基金Supported by the National Natural Science Foundation of China(12272248)。
文摘The method of integrating factors is used to study the conservation laws of the Herglotz type Birkhoffian systems in this paper.Firstly,the definition of the integrating factors of the Herglotz type Birkhoffian systems is given.Secondly,the relationship between the integrating factors and conservation laws is studied,and the conservation theorems of Herglotz type Birkhoff's equations and their inverse theorems are established.Thirdly,two types of generalized Killing equations for calculating integrating factors are given.Finally,as an example,a linear damped oscillator is taken.This example can be transformed into a Herglotz type Birkhoffian system.The resulting conservation theorems are used to find the conserved quantities for this example.
