With the widespread use of social media,the propagation of health-related rumors has become a significant public health threat.Existing methods for detecting health rumors predominantly rely on external knowledge or p...With the widespread use of social media,the propagation of health-related rumors has become a significant public health threat.Existing methods for detecting health rumors predominantly rely on external knowledge or propagation structures,with only a few recent approaches attempting causal inference;however,these have not yet effectively integrated causal discovery with domain-specific knowledge graphs for detecting health rumors.In this study,we found that the combined use of causal discovery and domain-specific knowledge graphs can effectively identify implicit pseudo-causal logic embedded within texts,holding significant potential for health rumor detection.To this end,we propose CKDG—a dual-graph fusion framework based on causal logic and medical knowledge graphs.CKDG constructs a weighted causal graph to capture the implicit causal relationships in the text and introduces a medical knowledge graph to verify semantic consistency,thereby enhancing the ability to identify the misuse of professional terminology and pseudoscientific claims.In experiments conducted on a dataset comprising 8430 health rumors,CKDG achieved an accuracy of 91.28%and an F1 score of 90.38%,representing improvements of 5.11%and 3.29%over the best baseline,respectively.Our results indicate that the integrated use of causal discovery and domainspecific knowledge graphs offers significant advantages for health rumor detection systems.This method not only improves detection performance but also enhances the transparency and credibility of model decisions by tracing causal chains and sources of knowledge conflicts.We anticipate that this work will provide key technological support for the development of trustworthy health-information filtering systems,thereby improving the reliability of public health information on social media.展开更多
By using error correction model, I conduct co-integration analysis on the research of the relationship between the per capita practical consumption and per capita practical disposable income of urban residents in Huna...By using error correction model, I conduct co-integration analysis on the research of the relationship between the per capita practical consumption and per capita practical disposable income of urban residents in Hunan Province from 1978 to 2009. The results show that there is a co-integration relationship between the per capita practical consumption and the practical per capita disposable income of urban residents, and based on these, the corresponding error correction model is established. Finally, corresponding countermeasures and suggestions are put forward as follows: broaden the income channel of urban residents; create goods consuming environment; perfect socialist security system.展开更多
Based on literature review,according to relevant consumption data in Hunan Statistical Yearbook and China Statistical Yearbook during1978-2009,the thesis selects three indexes involving the average income per rural re...Based on literature review,according to relevant consumption data in Hunan Statistical Yearbook and China Statistical Yearbook during1978-2009,the thesis selects three indexes involving the average income per rural resident,per capita living expenses of rural residents and percapita savings to conduct the unit root and co-integration test on the consumption and net income per rural residents in Hunan Province by adoptingthe generalized difference method and EVIEWS6.0,then according to the Modigliani Hypothesis of Consumption,Duesenberry Hypothesis of Con-sumption and Keynes Absolute Income Hypothesis,the thesis makes a fitting of Hunan consumption function model,aiming to find out the consump-tion function model suitable to Hunan Province.The results show that,Keynesian consumption function based on Absolute Income Hypothesis pas-ses the statistical test and econometric test,while the consumption function model based on Relative Income Hypothesis and that based on Life Cy-cle Hypothesis do not,which proves that the consumption function model based on Absolute Income Hypothesis is better suited for describing the re-lations between rural consumption and income in Hunan Province.Taking into account the low marginal propensity of consumption of the rural resi-dents in Hunan Province,the thesis proposes to expand consumption demand of rural residents:firstly,developing characteristic economy and im-proving the income level of rural residents;secondly,perfecting the social security system in rural areas and maintaining the consumption confi-dence of rural residents;thirdly,ameliorating the circulation system.展开更多
Enhancing the firefighting protective clothing with exceptional thermal barrier and temperature sensing functions to ensure high fire safety for firefighters has long been anticipated,but it remains a major challenge....Enhancing the firefighting protective clothing with exceptional thermal barrier and temperature sensing functions to ensure high fire safety for firefighters has long been anticipated,but it remains a major challenge.Herein,inspired by the human muscle,an anisotropic fire safety aerogel(ACMCA)with precise self-actuated temperature monitoring performance is developed by combining aramid nanofibers with eicosane/MXene to form an anisotropically oriented conductive network.By combining the two synergies of the negative temperaturedependent thermal conductive eicosane,which induces a high-temperature differential,and directionally ordered MXene that establishes a conductive network along the directional freezing direction.The resultant ACMCA exhibited remarkable thermoelectric properties,with S values reaching 46.78μV K^(−1)andκvalues as low as 0.048 W m^(−1)K^(−1)at room temperature.Moreover,the prepared anisotropic aerogel ACMCA exhibited electrical responsiveness to temperature variations,facilitating its application in intelligent temperature monitoring systems.The designed anisotropic aerogel ACMCA could be incorporated into the firefighting clothing as a thermal barrier layer,demonstrating a wide temperature sensing range(50-400℃)and a rapid response time for early high-temperature alerts(~1.43 s).This work provides novel insights into the design and application of temperature-sensitive anisotropic aramid nanofibers aerogel in firefighting clothing.展开更多
The digital economy has injected continuous momentum into the development of urban economy and plays a positive and important role in the transformation and upgrading of urban energy consumption.Specifically,the digit...The digital economy has injected continuous momentum into the development of urban economy and plays a positive and important role in the transformation and upgrading of urban energy consumption.Specifically,the digital economy can significantly improve the efficiency of urban energy consumption by virtue of its distinctive characteristics of low pollution and high efficiency.Moreover,empowered by the digital economy,the pace of transformation and upgrading of high-pollution traditional industries has been accelerated.Particularly importantly,the urban energy consumption structure has been optimized and adjusted through the indirect role of intermediate factors.From this perspective,studying the current situation and countermeasures of urban energy consumption under the digital economy holds important practical significance both in theory and practice.This paper first briefly summarizes the relevant literature on the impact of the digital economy on the energy consumption structure;then,it focuses on detailed data to explore the current situation of urban energy consumption under the digital economy model;finally,based on the summary of the current situation,it puts forward practical and feasible suggestions,hoping to provide a decision-making basis for the implementation of policies in different types of cities and offer innovative ideas for promoting the high-quality development of urban energy systems.展开更多
The electrochemical performance of layered O3-type NaCrO_(2)cathode material is significantly affected by the side reactions between NaCrO_(2)and electrolyte during sodium storage.A uniform Cr_(2)O_(3)coating layer wa...The electrochemical performance of layered O3-type NaCrO_(2)cathode material is significantly affected by the side reactions between NaCrO_(2)and electrolyte during sodium storage.A uniform Cr_(2)O_(3)coating layer was in situ constructed on the surface of NaCrO_(2)by controlling the excess ratio of sodium source.The structure,morphology,valence and electrochemical performance of the Cr_(2)O_(3)-coated NaCrO_(2)were characterized.The results indicate that the Cr_(2)O_(3)coating layer does not alter the crystal structure and morphology of NaCrO_(2),but effectively suppresses the side reactions between NaCrO_(2)and electrolyte,and improves the surface/interfacial stability of NaCrO_(2)material.The Cr_(2)O_(3)-coated NaCrO_(2)exhibits improved electrochemical performance with a capacity retention of 66.4%after 500 cycles at 10C.展开更多
In this work,several HZSM-5 catalysts with different Si/Al ratios treated with acids are selected as catalysts and used for hydration of cyclohexene to cyclohexanol.The results indicated that HZSM-5(Si/Al=38)modified ...In this work,several HZSM-5 catalysts with different Si/Al ratios treated with acids are selected as catalysts and used for hydration of cyclohexene to cyclohexanol.The results indicated that HZSM-5(Si/Al=38)modified with 4 mol·L^(-1) nitric acid was selected as an efficient catalyst for improving the hydration efficiency of cyclohexene.Furthermore,the microstructures and properties of fresh,used and regenerated acid-modified catalysts have been characterized by X-ray diffraction,scanning electron microscopy,nitrogen adsorption/desorption isotherm,Fourier transform infrared,thermal gravimetric analyzer,ammonia temperature programmed desorption and pyridine adsorbs Fourier transform infrared.The characterization results indicated that the total surface areas and pore volume of HZSM-5 zeolite increased after nitric acid treatment due to the formation of mesoporous structure.This benefits the diffusion rate of reactants and products,which improves the hydration efficiency and stability of the catalyst.Under the catalysis of HZSM-5,the conversion of cyclohexene was found to be 9.0%.However,treatment of HZSM-5 with nitric acid enhanced the conversion of cyclohexene to 12.2%,achieving a selectivity of 99.7%for cyclohexanol under optimal reaction conditions.This work affords a mild and efficient approach for improving the hydration efficiency and has potential industrial application value.展开更多
This study primarily investigates the effect of CeO_(2)content on the microstructure and mechanical properties of ZK60 Mg alloy.The results indicate that CeO_(2)can be reduced by Mg to elemental Ce,predominantly in th...This study primarily investigates the effect of CeO_(2)content on the microstructure and mechanical properties of ZK60 Mg alloy.The results indicate that CeO_(2)can be reduced by Mg to elemental Ce,predominantly in the form of the Mg-Zn-Ce phase.The addition of CeO_(2)notably refines the grain size of as-cast ZK60 Mg alloy,with the Mg-Zn-Ce phase primarily distributed along grain boundaries.After extrusion,grain size increases and then decreases with increasing CeO_(2)content,while the dynamic recrystallization(DRX)fraction gradually reduces.This behavior is chiefly attributed to the hindrance of the DRX process by a high density of second phases and the restriction of recrystallized grains growth by fine particles.The basal texture intensity increases progressively with the addition of CeO_(2).As the CeO_(2)content rises,the yield strength(YS)and elongation(EL)of the alloys show significant improvement.The increase in YS is mainly due to the combined effects of grain refinement strengthening and dispersion strengthening.In contrast,the enhanced EL is closely related to the heterogeneous structure of the grains.Notably,the ZK60-1.2CeO_(2)alloy exhibits the ultimate tensile strength,YS and EL of 274 MPa,160 MPa and 17.3%,respectively.展开更多
P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) was synthesized by a facile sol−gel method,and the effect of calcination temperature on the structure,morphology and electrochemical performance of samples was investigated.The re...P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) was synthesized by a facile sol−gel method,and the effect of calcination temperature on the structure,morphology and electrochemical performance of samples was investigated.The results show that the sample obtained at 900℃ is pure P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) phase with good crystallization,which consists of hexagon plate-shaped particles with the size and thickness of 2−4μm and 200−400 nm,respectively.The sample exhibits an initial specific discharge capacity of 243 mA·h/g at a current density of 26 mA/g with good cycling stability.The high specific capacity indicates that P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) is a promising cathode material for sodiumion batteries.展开更多
Spherical LiNi0.8Co0.15Al0.05O2 OOH precursor prepared by a co-oxidation-controlled crystallization method, was used to synthesize LiNi0.5Co0.15Al0.05O2. The obtained LiNi0.8Co0.15Al0.05O2 materials showed excellent e...Spherical LiNi0.8Co0.15Al0.05O2 OOH precursor prepared by a co-oxidation-controlled crystallization method, was used to synthesize LiNi0.5Co0.15Al0.05O2. The obtained LiNi0.8Co0.15Al0.05O2 materials showed excellent electrochemical performance, with an initial discharge capacity of 193.5 mAh/g and capacity retention of 95.1% after 50 cycles when cycled at 0.2 C rate between 2.8 and 4.3 V.展开更多
Impact dampers are usually used to suppress single mode resonance. The goal of this paper is to clarify the difference when the impact damper suppresses the resonances of different modes. A cantilever beam equipped wi...Impact dampers are usually used to suppress single mode resonance. The goal of this paper is to clarify the difference when the impact damper suppresses the resonances of different modes. A cantilever beam equipped with the impact damper is modeled. The elastic contact of the ball and the cantilever beam is described by using the Hertz contact model. The viscous damper between the ball and the cantilever beam is modeled to consume the vibrational energy of the cantilever beam. A piecewise ordinary differential-partial differential equation of the cantilever beam is established, including equations with and without the impact damper. The vibration responses of the cantilever beam with and without the impact damper are numerically calculated. The effects of the impact absorber parameters on the vibration reduction are examined. The results show that multiple resonance peaks of the cantilever beam can be effectively suppressed by the impact damper. Specifically, all resonance amplitudes can be reduced by a larger weight ball. Moreover, the impacting gap is very effective in suppressing the vibration of the cantilever beam. More importantly, there is an optimal impacting gap for each resonance mode of the cantilever beam, but the optimal gap for each mode is different.展开更多
The dissimilar joints of AZ61 and ZK60 magnesium alloys were obtained by tungsten inert gas arc(TIG)welding and activating tungsten inert gas arc(A-TIG)welding processes.Microstructure characterization shows that,the ...The dissimilar joints of AZ61 and ZK60 magnesium alloys were obtained by tungsten inert gas arc(TIG)welding and activating tungsten inert gas arc(A-TIG)welding processes.Microstructure characterization shows that,the fineα-Mg equiaxed dendrite crystals contained Mg17Al12 and MgZn2 particles in the fusion zone.The average size of theα-Mg grains in the fusion zone was refined to 19μm at welding current of 80 A,which resulted in the largest tensile strength of 207 MPa.The tensile strength and the width of the beam of the A-TIG welded AZ61/ZK60 joints showed strong dependence on the amount of TiO2.However,the inhomogeneity of the heat-affected zone near different base metals presented no significant effect on the mechanical properties of the welded joint.展开更多
Different LiNi0.8Co0.15Al0.05O2 cathode materials were washed by ethanol solvent. Inductively coupled plasma atomic emission spectroscopy（ICP-AES）, Fourier transformed infrared（FTIR） spectrum, X-ray diffraction（...Different LiNi0.8Co0.15Al0.05O2 cathode materials were washed by ethanol solvent. Inductively coupled plasma atomic emission spectroscopy（ICP-AES）, Fourier transformed infrared（FTIR） spectrum, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, charge-discharge test and electrochemical impedance spectroscopy（EIS） were used to evaluate the elemental contents, structures, morphologies and electrochemical properties of samples. The results show that ethanol washing can remove effectively the synthetic residues LiOH/Li2 O on the freshly-prepared LiNi0.8Co0.15Al0.05O2 and make the sample much more resistant to H2O and CO2, without destroying its bulk structure, surface morphology and electrochemical performances. Moreover, the discharge specific capacity and cycle performance of LiNi0.8Co0.15Al0.05O2 after storage in air with a relative humidity of 80% for three months are improved by immediate ethanol washing.展开更多
The photocatalytic degradation kinetics of carbofuran was optimized by central composite design based on response surface methodology for the first time. Three variables, TiO2 concentration, initial pH value and the c...The photocatalytic degradation kinetics of carbofuran was optimized by central composite design based on response surface methodology for the first time. Three variables, TiO2 concentration, initial pH value and the concentration of carbofuran, were selected to determine the dependence of degradation efficiencies on independent variables. Response surface methodology modeling results indicated that the degradation efficiency of carbofuran was highly affected by the initial pH value and the concentration of carbofuran. Then nine degradation intermediates were detected by HPLC/MS/MS. The Frontier Electron Densities of carbofuran were calculated to predict the active sites on carbofuran attacked by hydroxyl radicals and photoholes. Point charges were used to elucidate the chemisorption pattern on TiO2 catalysts during the photocatalytic process. By combining the experimental results and calculation data, the photocatalytic degradation pathways of carbofuran were proposed, including the addition of hydroxyl radicals and the cleavage of the carbamate side chain.展开更多
Composite coatings consisting of carbon and polytetrafluoroethylene(PTFE) were prepared on Ti alloy substrate by a simple two-step process of hydrothermal and impregnation. The morphology, composition, hydrophobic and...Composite coatings consisting of carbon and polytetrafluoroethylene(PTFE) were prepared on Ti alloy substrate by a simple two-step process of hydrothermal and impregnation. The morphology, composition, hydrophobic and corrosion properties of the composite coatings were characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), water contact angle method, X-ray photoelectron spectroscopy(XPS) and electrochemical technique, respectively. The effect of PTFE content on the corrosion properties of the composite coatings was studied. It is found that the composite coating film exhibits a full coverage with uniformly distributed PTFE when 0.1 mol/L of glucose is used as carbon source and 20 wt.% PTFE suspension as impregnating solution. The coating with 20 wt.% PTFE has a good bonding strength with Ti plate and exhibits excellent hydrophobic property with a water contact angle of 142.3° as well as superior corrosion resistance with corrosion current density as low as 0.0045 μA/cm^2. With regard to its excellent hydrophobicity and corrosion resistance, the carbon-PTFE composite coating may find potential application in automobiles and metal corrosion industries.展开更多
Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a ...Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).展开更多
The asymmetric semi-circular bend(ASCB)specimen has been proposed to investigate the cracking behavior in different geo and construction materials and attracted the attention of researchers due to its advantages.Howev...The asymmetric semi-circular bend(ASCB)specimen has been proposed to investigate the cracking behavior in different geo and construction materials and attracted the attention of researchers due to its advantages.However,there are few studies on the fracture toughness determination of rock materials.In this work,a series of fracture tests were performed with the ASCB specimens made of granite.The onset of fracture,crack initiation angle and crack propagating trajectory was analyzed in detail combined with several mixed mode fracture criteria.The influence of the crack length on the mode Ⅰ/Ⅱ fracture toughness was studied.A comparison between the fracture toughness ratios predicted by varying criteria and experimental results was conducted.The relationship between experimentally determined crack initiation angles and curves of the generalized maximum tangential stress(GMTS)criterion was obtained.The fracture process of the specimen was recorded with the high-speed camera.The shortcomings of the ASCB specimens for the fracture toughness determination of rock materials were discussed.The results may provide a reference for analysis of mixed mode I and II fracture behavior of brittle materials.展开更多
To improve the adsorption performance and simplify uranium separation from aqueous media in post-treatment processes,a magnetic CoFe_(2)O_(4)@rGO composite was synthesized by microwave-hydrothermal method.The results ...To improve the adsorption performance and simplify uranium separation from aqueous media in post-treatment processes,a magnetic CoFe_(2)O_(4)@rGO composite was synthesized by microwave-hydrothermal method.The results of XRD,Raman,TEM/HRTEM,FTIR,BET and VSM characterization show that spinel-type cobalt ferrite CoFe_(2)O_(4) nanoparticles ca.13.4 nm in size are dispersedly anchored on the graphene sheet,and the saturation magnetization of the nanocomposite is 46.7 mA/(m^(2)·g).The effects of different pH,initial concentration and other conditions on uranium adsorption capacity were investigated,and adsorption kinetics equations were fitted to determine the adsorption behaviour of uranium on CoFe_(2)O_(4)@rGO in simulated uranium-containing seawater.It was observed that the uranium adsorption capacity of CoFe_(2)O_(4)@rGO composite at pH=5 is 127.6 mg/g,which is 1.31 and 2.43 times that of rGO and pure CoFe_(2)O_(4).The adsorption process conforms to Langmuir and quasi-second-order kinetic model.The excellent adsorption performance of CoFe_(2)O_(4)@rGO makes it potentially useful in the treatment of uranium-polluted water.展开更多
The mechanical behavior of EPS(Expanded polystyrene) with three densities at room temperature and under tension loading was studied.The results show that EPS material is characterized by brittle behavior in the tensio...The mechanical behavior of EPS(Expanded polystyrene) with three densities at room temperature and under tension loading was studied.The results show that EPS material is characterized by brittle behavior in the tension tests,and tensile properties of EPS increase with the increase of density.Volume fraction has no a significant effect on the modulus of these foams.The tensile creep strain increases with stress for EPS with same density,indicating that the creep behavior is of the stress dependency.And the creep behavior of EPS exhibits density dependency,which the creep strain decreases with densities for a fixed stress value.Moreover the creep behavior under the constant tension load is well in coincidence with the three-parameter solid model.展开更多
基金funded by the Hunan Provincial Natural Science Foundation of China(Grant No.2025JJ70105)the Hunan Provincial College Students’Innovation and Entrepreneurship Training Program(Project No.S202411342056)The article processing charge(APC)was funded by the Project No.2025JJ70105.
文摘With the widespread use of social media,the propagation of health-related rumors has become a significant public health threat.Existing methods for detecting health rumors predominantly rely on external knowledge or propagation structures,with only a few recent approaches attempting causal inference;however,these have not yet effectively integrated causal discovery with domain-specific knowledge graphs for detecting health rumors.In this study,we found that the combined use of causal discovery and domain-specific knowledge graphs can effectively identify implicit pseudo-causal logic embedded within texts,holding significant potential for health rumor detection.To this end,we propose CKDG—a dual-graph fusion framework based on causal logic and medical knowledge graphs.CKDG constructs a weighted causal graph to capture the implicit causal relationships in the text and introduces a medical knowledge graph to verify semantic consistency,thereby enhancing the ability to identify the misuse of professional terminology and pseudoscientific claims.In experiments conducted on a dataset comprising 8430 health rumors,CKDG achieved an accuracy of 91.28%and an F1 score of 90.38%,representing improvements of 5.11%and 3.29%over the best baseline,respectively.Our results indicate that the integrated use of causal discovery and domainspecific knowledge graphs offers significant advantages for health rumor detection systems.This method not only improves detection performance but also enhances the transparency and credibility of model decisions by tracing causal chains and sources of knowledge conflicts.We anticipate that this work will provide key technological support for the development of trustworthy health-information filtering systems,thereby improving the reliability of public health information on social media.
基金Supported by the Scientific Research Subject of Department of Education in Hunan Province(10C0556)
文摘By using error correction model, I conduct co-integration analysis on the research of the relationship between the per capita practical consumption and per capita practical disposable income of urban residents in Hunan Province from 1978 to 2009. The results show that there is a co-integration relationship between the per capita practical consumption and the practical per capita disposable income of urban residents, and based on these, the corresponding error correction model is established. Finally, corresponding countermeasures and suggestions are put forward as follows: broaden the income channel of urban residents; create goods consuming environment; perfect socialist security system.
文摘Based on literature review,according to relevant consumption data in Hunan Statistical Yearbook and China Statistical Yearbook during1978-2009,the thesis selects three indexes involving the average income per rural resident,per capita living expenses of rural residents and percapita savings to conduct the unit root and co-integration test on the consumption and net income per rural residents in Hunan Province by adoptingthe generalized difference method and EVIEWS6.0,then according to the Modigliani Hypothesis of Consumption,Duesenberry Hypothesis of Con-sumption and Keynes Absolute Income Hypothesis,the thesis makes a fitting of Hunan consumption function model,aiming to find out the consump-tion function model suitable to Hunan Province.The results show that,Keynesian consumption function based on Absolute Income Hypothesis pas-ses the statistical test and econometric test,while the consumption function model based on Relative Income Hypothesis and that based on Life Cy-cle Hypothesis do not,which proves that the consumption function model based on Absolute Income Hypothesis is better suited for describing the re-lations between rural consumption and income in Hunan Province.Taking into account the low marginal propensity of consumption of the rural resi-dents in Hunan Province,the thesis proposes to expand consumption demand of rural residents:firstly,developing characteristic economy and im-proving the income level of rural residents;secondly,perfecting the social security system in rural areas and maintaining the consumption confi-dence of rural residents;thirdly,ameliorating the circulation system.
基金funding support from Guiding Project of Scientific Research Plan of Education Department of Hubei Province and Wuhan Textile University School Fund(B)(k24016).
文摘Enhancing the firefighting protective clothing with exceptional thermal barrier and temperature sensing functions to ensure high fire safety for firefighters has long been anticipated,but it remains a major challenge.Herein,inspired by the human muscle,an anisotropic fire safety aerogel(ACMCA)with precise self-actuated temperature monitoring performance is developed by combining aramid nanofibers with eicosane/MXene to form an anisotropically oriented conductive network.By combining the two synergies of the negative temperaturedependent thermal conductive eicosane,which induces a high-temperature differential,and directionally ordered MXene that establishes a conductive network along the directional freezing direction.The resultant ACMCA exhibited remarkable thermoelectric properties,with S values reaching 46.78μV K^(−1)andκvalues as low as 0.048 W m^(−1)K^(−1)at room temperature.Moreover,the prepared anisotropic aerogel ACMCA exhibited electrical responsiveness to temperature variations,facilitating its application in intelligent temperature monitoring systems.The designed anisotropic aerogel ACMCA could be incorporated into the firefighting clothing as a thermal barrier layer,demonstrating a wide temperature sensing range(50-400℃)and a rapid response time for early high-temperature alerts(~1.43 s).This work provides novel insights into the design and application of temperature-sensitive anisotropic aramid nanofibers aerogel in firefighting clothing.
文摘The digital economy has injected continuous momentum into the development of urban economy and plays a positive and important role in the transformation and upgrading of urban energy consumption.Specifically,the digital economy can significantly improve the efficiency of urban energy consumption by virtue of its distinctive characteristics of low pollution and high efficiency.Moreover,empowered by the digital economy,the pace of transformation and upgrading of high-pollution traditional industries has been accelerated.Particularly importantly,the urban energy consumption structure has been optimized and adjusted through the indirect role of intermediate factors.From this perspective,studying the current situation and countermeasures of urban energy consumption under the digital economy holds important practical significance both in theory and practice.This paper first briefly summarizes the relevant literature on the impact of the digital economy on the energy consumption structure;then,it focuses on detailed data to explore the current situation of urban energy consumption under the digital economy model;finally,based on the summary of the current situation,it puts forward practical and feasible suggestions,hoping to provide a decision-making basis for the implementation of policies in different types of cities and offer innovative ideas for promoting the high-quality development of urban energy systems.
基金supported by the Scientific Research Fund of Hunan Provincial Education Department,China(No.22B0741)。
文摘The electrochemical performance of layered O3-type NaCrO_(2)cathode material is significantly affected by the side reactions between NaCrO_(2)and electrolyte during sodium storage.A uniform Cr_(2)O_(3)coating layer was in situ constructed on the surface of NaCrO_(2)by controlling the excess ratio of sodium source.The structure,morphology,valence and electrochemical performance of the Cr_(2)O_(3)-coated NaCrO_(2)were characterized.The results indicate that the Cr_(2)O_(3)coating layer does not alter the crystal structure and morphology of NaCrO_(2),but effectively suppresses the side reactions between NaCrO_(2)and electrolyte,and improves the surface/interfacial stability of NaCrO_(2)material.The Cr_(2)O_(3)-coated NaCrO_(2)exhibits improved electrochemical performance with a capacity retention of 66.4%after 500 cycles at 10C.
基金financial support by the National Natural Science Foundation of China(22378339)Collaborative Innovation Center of New Chemical Technologies for Environmental Benignity and Efficient Resource Utilization.
文摘In this work,several HZSM-5 catalysts with different Si/Al ratios treated with acids are selected as catalysts and used for hydration of cyclohexene to cyclohexanol.The results indicated that HZSM-5(Si/Al=38)modified with 4 mol·L^(-1) nitric acid was selected as an efficient catalyst for improving the hydration efficiency of cyclohexene.Furthermore,the microstructures and properties of fresh,used and regenerated acid-modified catalysts have been characterized by X-ray diffraction,scanning electron microscopy,nitrogen adsorption/desorption isotherm,Fourier transform infrared,thermal gravimetric analyzer,ammonia temperature programmed desorption and pyridine adsorbs Fourier transform infrared.The characterization results indicated that the total surface areas and pore volume of HZSM-5 zeolite increased after nitric acid treatment due to the formation of mesoporous structure.This benefits the diffusion rate of reactants and products,which improves the hydration efficiency and stability of the catalyst.Under the catalysis of HZSM-5,the conversion of cyclohexene was found to be 9.0%.However,treatment of HZSM-5 with nitric acid enhanced the conversion of cyclohexene to 12.2%,achieving a selectivity of 99.7%for cyclohexanol under optimal reaction conditions.This work affords a mild and efficient approach for improving the hydration efficiency and has potential industrial application value.
基金the financial supports from the National Natural Science Foundation of China(Nos.52171099,51301025,51140001)the Education Department of Hunan Province of China(No.22A0240)the State Key Laboratory of Disaster Prevention&Reduction for Power Grid,Changsha University of Science&Technology.
文摘This study primarily investigates the effect of CeO_(2)content on the microstructure and mechanical properties of ZK60 Mg alloy.The results indicate that CeO_(2)can be reduced by Mg to elemental Ce,predominantly in the form of the Mg-Zn-Ce phase.The addition of CeO_(2)notably refines the grain size of as-cast ZK60 Mg alloy,with the Mg-Zn-Ce phase primarily distributed along grain boundaries.After extrusion,grain size increases and then decreases with increasing CeO_(2)content,while the dynamic recrystallization(DRX)fraction gradually reduces.This behavior is chiefly attributed to the hindrance of the DRX process by a high density of second phases and the restriction of recrystallized grains growth by fine particles.The basal texture intensity increases progressively with the addition of CeO_(2).As the CeO_(2)content rises,the yield strength(YS)and elongation(EL)of the alloys show significant improvement.The increase in YS is mainly due to the combined effects of grain refinement strengthening and dispersion strengthening.In contrast,the enhanced EL is closely related to the heterogeneous structure of the grains.Notably,the ZK60-1.2CeO_(2)alloy exhibits the ultimate tensile strength,YS and EL of 274 MPa,160 MPa and 17.3%,respectively.
基金the financial supports from the Natural Science Foundation of Hunan Province,China(No.2020JJ5102)the Scientific Research Fund of Hunan Provincial Education Department,China(No.19A111).
文摘P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) was synthesized by a facile sol−gel method,and the effect of calcination temperature on the structure,morphology and electrochemical performance of samples was investigated.The results show that the sample obtained at 900℃ is pure P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) phase with good crystallization,which consists of hexagon plate-shaped particles with the size and thickness of 2−4μm and 200−400 nm,respectively.The sample exhibits an initial specific discharge capacity of 243 mA·h/g at a current density of 26 mA/g with good cycling stability.The high specific capacity indicates that P2-type Na_(2/3)Fe_(1/2)Mn_(1/2)O_(2) is a promising cathode material for sodiumion batteries.
基金supported by National Natural Science Foundation of China(No.50604018)National Key Technology R&D Program of China(No.2007BAE12B01)
文摘Spherical LiNi0.8Co0.15Al0.05O2 OOH precursor prepared by a co-oxidation-controlled crystallization method, was used to synthesize LiNi0.5Co0.15Al0.05O2. The obtained LiNi0.8Co0.15Al0.05O2 materials showed excellent electrochemical performance, with an initial discharge capacity of 193.5 mAh/g and capacity retention of 95.1% after 50 cycles when cycled at 0.2 C rate between 2.8 and 4.3 V.
基金Supported by the Natural Science Foundation of Hunan Province （07JJ6112）, the Construct Program of the Key Discipline in Hunan Province （control theory and control engineering）, and Scientific Research Fund of Hunan Provincial Education Department （04A012, 07A015）
基金the National Natural Science Foundation of China(No.11772181)the Program of Shanghai Municipal Education Commission(No.2019-01-07-00-09-E0018)the Key Research Projects of Shanghai Science and Technology Commission(No.18010500100)。
文摘Impact dampers are usually used to suppress single mode resonance. The goal of this paper is to clarify the difference when the impact damper suppresses the resonances of different modes. A cantilever beam equipped with the impact damper is modeled. The elastic contact of the ball and the cantilever beam is described by using the Hertz contact model. The viscous damper between the ball and the cantilever beam is modeled to consume the vibrational energy of the cantilever beam. A piecewise ordinary differential-partial differential equation of the cantilever beam is established, including equations with and without the impact damper. The vibration responses of the cantilever beam with and without the impact damper are numerically calculated. The effects of the impact absorber parameters on the vibration reduction are examined. The results show that multiple resonance peaks of the cantilever beam can be effectively suppressed by the impact damper. Specifically, all resonance amplitudes can be reduced by a larger weight ball. Moreover, the impacting gap is very effective in suppressing the vibration of the cantilever beam. More importantly, there is an optimal impacting gap for each resonance mode of the cantilever beam, but the optimal gap for each mode is different.
基金Project(51771160)supported by the National Natural Science Foundation of ChinaProject(2018JJ4048)supported by the Provincial and Municipal Joint Fund for Natural Science of Hunan Province,China
文摘The dissimilar joints of AZ61 and ZK60 magnesium alloys were obtained by tungsten inert gas arc(TIG)welding and activating tungsten inert gas arc(A-TIG)welding processes.Microstructure characterization shows that,the fineα-Mg equiaxed dendrite crystals contained Mg17Al12 and MgZn2 particles in the fusion zone.The average size of theα-Mg grains in the fusion zone was refined to 19μm at welding current of 80 A,which resulted in the largest tensile strength of 207 MPa.The tensile strength and the width of the beam of the A-TIG welded AZ61/ZK60 joints showed strong dependence on the amount of TiO2.However,the inhomogeneity of the heat-affected zone near different base metals presented no significant effect on the mechanical properties of the welded joint.
基金Projects(15B054,17C0400) supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProjects(2017JJ2060,2015JJ2042) supported by the Natural Science Foundation of Hunan Province,ChinaProject(2014-207) supported by the Aid Program for Science and Technology Innovative Research Team in Higher Educational Instituions of Hunan Province,China
文摘Different LiNi0.8Co0.15Al0.05O2 cathode materials were washed by ethanol solvent. Inductively coupled plasma atomic emission spectroscopy（ICP-AES）, Fourier transformed infrared（FTIR） spectrum, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, charge-discharge test and electrochemical impedance spectroscopy（EIS） were used to evaluate the elemental contents, structures, morphologies and electrochemical properties of samples. The results show that ethanol washing can remove effectively the synthetic residues LiOH/Li2 O on the freshly-prepared LiNi0.8Co0.15Al0.05O2 and make the sample much more resistant to H2O and CO2, without destroying its bulk structure, surface morphology and electrochemical performances. Moreover, the discharge specific capacity and cycle performance of LiNi0.8Co0.15Al0.05O2 after storage in air with a relative humidity of 80% for three months are improved by immediate ethanol washing.
基金supported by the National Natural Science Foundation of China (No.21207034, 21172064)the Provincial Natural Science Foundation of Hunan (No.10JJ2006)the Key Scientific Research Fund of Hunan Provincial Education Department (No.10A022)
文摘The photocatalytic degradation kinetics of carbofuran was optimized by central composite design based on response surface methodology for the first time. Three variables, TiO2 concentration, initial pH value and the concentration of carbofuran, were selected to determine the dependence of degradation efficiencies on independent variables. Response surface methodology modeling results indicated that the degradation efficiency of carbofuran was highly affected by the initial pH value and the concentration of carbofuran. Then nine degradation intermediates were detected by HPLC/MS/MS. The Frontier Electron Densities of carbofuran were calculated to predict the active sites on carbofuran attacked by hydroxyl radicals and photoholes. Point charges were used to elucidate the chemisorption pattern on TiO2 catalysts during the photocatalytic process. By combining the experimental results and calculation data, the photocatalytic degradation pathways of carbofuran were proposed, including the addition of hydroxyl radicals and the cleavage of the carbamate side chain.
基金Project(2018YFB1502500) supported by the National Key Research and Development Program of ChinaProject supported by State Key Laboratory of Powder Metallurgy,Central South University,China+1 种基金Projects(21506258,51774127) supported by the National Natural Science Foundation of ChinaProject(2019RS2067) supported by the Science and Technology Planning Project of Hunan Province,China
文摘Composite coatings consisting of carbon and polytetrafluoroethylene(PTFE) were prepared on Ti alloy substrate by a simple two-step process of hydrothermal and impregnation. The morphology, composition, hydrophobic and corrosion properties of the composite coatings were characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), water contact angle method, X-ray photoelectron spectroscopy(XPS) and electrochemical technique, respectively. The effect of PTFE content on the corrosion properties of the composite coatings was studied. It is found that the composite coating film exhibits a full coverage with uniformly distributed PTFE when 0.1 mol/L of glucose is used as carbon source and 20 wt.% PTFE suspension as impregnating solution. The coating with 20 wt.% PTFE has a good bonding strength with Ti plate and exhibits excellent hydrophobic property with a water contact angle of 142.3° as well as superior corrosion resistance with corrosion current density as low as 0.0045 μA/cm^2. With regard to its excellent hydrophobicity and corrosion resistance, the carbon-PTFE composite coating may find potential application in automobiles and metal corrosion industries.
基金Supported by the National Natural Science Foundation of China(21476065)the China National Tobacco Corporation
文摘Micro-encapsulated phase-change materials(micro PCMs) with Na_2 HPO_4·12 H_2 O encapsulated in poly(lactic acid)(PLA) shell were prepared by a solvent evaporation–precipitation method that involves the use of a coaxial needle. The effects of PLA concentration, stirring speed, injection rate of core and shell solutions, and polyvinyl alcohol(PVA) concentration on phase change properties were investigated. The thermal properties of microP CMs were characterized by differential scanning calorimetry(DSC). The capsules prepared under the optimal conditions are about 2 mm in diameter and show a latent heat of up to 122.2 J·g^(-1).
基金Projects(52004182,51804110,51904101)supported by the National Natural Science Foundation of ChinaProject(2020JJ5188)supported by the Natural Science Foundation of Hunan Province,China。
文摘The asymmetric semi-circular bend(ASCB)specimen has been proposed to investigate the cracking behavior in different geo and construction materials and attracted the attention of researchers due to its advantages.However,there are few studies on the fracture toughness determination of rock materials.In this work,a series of fracture tests were performed with the ASCB specimens made of granite.The onset of fracture,crack initiation angle and crack propagating trajectory was analyzed in detail combined with several mixed mode fracture criteria.The influence of the crack length on the mode Ⅰ/Ⅱ fracture toughness was studied.A comparison between the fracture toughness ratios predicted by varying criteria and experimental results was conducted.The relationship between experimentally determined crack initiation angles and curves of the generalized maximum tangential stress(GMTS)criterion was obtained.The fracture process of the specimen was recorded with the high-speed camera.The shortcomings of the ASCB specimens for the fracture toughness determination of rock materials were discussed.The results may provide a reference for analysis of mixed mode I and II fracture behavior of brittle materials.
基金Project(19B126)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProject(21772035)supported by the National Natural Science Foundation of China+1 种基金Projects(2018JJ3099,2019JJ40058)supported by the Provincial Natural Science Foundation of Hunan,ChinaProject supported by the Innovation and Entrepreneurship Training Program of Hunan Institute of Engineering,China。
文摘To improve the adsorption performance and simplify uranium separation from aqueous media in post-treatment processes,a magnetic CoFe_(2)O_(4)@rGO composite was synthesized by microwave-hydrothermal method.The results of XRD,Raman,TEM/HRTEM,FTIR,BET and VSM characterization show that spinel-type cobalt ferrite CoFe_(2)O_(4) nanoparticles ca.13.4 nm in size are dispersedly anchored on the graphene sheet,and the saturation magnetization of the nanocomposite is 46.7 mA/(m^(2)·g).The effects of different pH,initial concentration and other conditions on uranium adsorption capacity were investigated,and adsorption kinetics equations were fitted to determine the adsorption behaviour of uranium on CoFe_(2)O_(4)@rGO in simulated uranium-containing seawater.It was observed that the uranium adsorption capacity of CoFe_(2)O_(4)@rGO composite at pH=5 is 127.6 mg/g,which is 1.31 and 2.43 times that of rGO and pure CoFe_(2)O_(4).The adsorption process conforms to Langmuir and quasi-second-order kinetic model.The excellent adsorption performance of CoFe_(2)O_(4)@rGO makes it potentially useful in the treatment of uranium-polluted water.
基金Project(06C243) supported by Scientific Research Fund of Hunan Provincial Education Department,China
文摘The mechanical behavior of EPS(Expanded polystyrene) with three densities at room temperature and under tension loading was studied.The results show that EPS material is characterized by brittle behavior in the tension tests,and tensile properties of EPS increase with the increase of density.Volume fraction has no a significant effect on the modulus of these foams.The tensile creep strain increases with stress for EPS with same density,indicating that the creep behavior is of the stress dependency.And the creep behavior of EPS exhibits density dependency,which the creep strain decreases with densities for a fixed stress value.Moreover the creep behavior under the constant tension load is well in coincidence with the three-parameter solid model.
