MXene,a transition metal carbide/nitride,has been prominent as an ideal electrochemical active material for supercapacitors.However,the low MXene load limits its practical applications.As environmental concerns and su...MXene,a transition metal carbide/nitride,has been prominent as an ideal electrochemical active material for supercapacitors.However,the low MXene load limits its practical applications.As environmental concerns and sustainable development become more widely recognized,it is necessary to explore a greener and cleaner technology to recycle textile by-products such as cotton.The present study proposes an effective 3D fabrication method that uses MXene to fabricate waste denim felt into ultralight and flexible supercapacitors through needling and carbonization.The 3D structure provided more sites for loading MXene onto Z-directional fiber bundles,resulting in more efficient ion exchange between the electrolyte and electrodes.Furthermore,the carbonization process removed the specific adverse groups in MXenes,further improving the specific capacitance,energy density,power density and electrical conductivity of supercapacitors.The electrodes achieve a maximum specific capacitance of 1748.5 mF cm-2 and demonstrate remarkable cycling stability maintaining more than 94%after 15,000 galvanostatic charge/discharge cycles.Besides,the obtained supercapacitors present a maximum specific capacitance of 577.5 mF cm^(-2),energy density of 80.2μWh cm^(-2)and power density of 3 mW cm^(-2),respectively.The resulting supercapacitors can be used to develop smart wearable power devices such as smartwatches,laying the foundation for a novel strategy of utilizing waste cotton in a high-quality manner.展开更多
The growth of γ-In_(2)Se_(3) thin films on mica by molecular beam epitaxy is studied. Single-crystalline γ-In_(2)Se_(3) is achieved at a relatively low growth temperature. An ultrathin β-In_(2)Se_(3) buffer layer i...The growth of γ-In_(2)Se_(3) thin films on mica by molecular beam epitaxy is studied. Single-crystalline γ-In_(2)Se_(3) is achieved at a relatively low growth temperature. An ultrathin β-In_(2)Se_(3) buffer layer is observed to nucleate and grow through a process of self-organization at initial deposition, which facilitates subsequent monolithic epitaxy of single-crystallineγ-In_(2)Se_(3) at low temperature. Strong room-temperature photoluminescence and moderate optoelectronic response are observed in the achieved γ-In_(2)Se_(3) thin films.展开更多
Chronic disease is an important factor that affect the health of elderly people. We analyzed the 2006 and 2010 data from the Chinese Urban and Rural Elderly Population Surveys, which are nationally representative surv...Chronic disease is an important factor that affect the health of elderly people. We analyzed the 2006 and 2010 data from the Chinese Urban and Rural Elderly Population Surveys, which are nationally representative surveys of elderly people aged 60 years and above. We found that there existed a typical power-law distribution for the rates of different numbers of chronic diseases among elderly Chinese people. A Kolmogorov-Smirnov test indicated that the result was robust, and the power exponents were approximately ?2.5. In addition, a paired t-test was conducted, which demonstrated that the rates of different numbers of chronic diseases did not have significant urban-rural differences, time differences or gender differences.展开更多
This paper reviews the original achievements and advances regarding the field effect transistor(FET) fabricated from one of the most studied transition metal dichalcogenides: two-dimensional Mo S2. Not like graphene, ...This paper reviews the original achievements and advances regarding the field effect transistor(FET) fabricated from one of the most studied transition metal dichalcogenides: two-dimensional Mo S2. Not like graphene, which is highlighted by a gapless Dirac cone band structure, Monolayer Mo S2 is featured with a 1.9 e V gapped direct energy band thus facilitates convenient electronic and/or optoelectronic modulation of its physical properties in FET structure. Indeed,many Mo S2 devices based on FET architecture such as phototransistors, memory devices, and sensors have been studied and extraordinary properties such as excellent mobility, ON/OFF ratio, and sensitivity of these devices have been exhibited. However, further developments in FET device applications depend a lot on if novel physics would be involved in them. In this review, an overview on advances and developments in the Mo S2-based FETs are presented. Engineering of Mo S2-based FETs will be discussed in details for understanding contact physics, formation of gate dielectric, and doping strategies. Also reported are demonstrations of device behaviors such as low-frequency noise and photoresponse in Mo S2-based FETs, which is crucial for developing electronic and optoelectronic devices.展开更多
In order to find viable alternative protein sources for aquaculture,we evaluated the effect of partial or complete replacement of dietary soybean meal with yellow mealworm(TM)on the flesh quality of grass carp.In this...In order to find viable alternative protein sources for aquaculture,we evaluated the effect of partial or complete replacement of dietary soybean meal with yellow mealworm(TM)on the flesh quality of grass carp.In this study,180 grass carp(511.85±0.25 g)were fed 3 experimental diets in which 0%(CN),30%(YM30)and 100%(YM100)dietary soybean meal was replaced by TM for 90 d.The results showed that growth performance,biological parameters and serum antioxidant capacity of grass carp were not affected by dietary TM(P>0.05).Both muscle and whole body crude protein were obviously promoted with the increase of dietary TM(P<0.05),and the concentration of heavy metal in muscle was not influenced(P>0.05),indicating that food safety was not influenced by TM.Dietary TM improved muscle textural characteristics by elevating adhesiveness,springiness and chewiness in YM100(P<0.05).In addition,the muscle tenderness was significantly increased by declining the shear force(P<0.05).The muscle fiber density in YM30&YM100 and length of dark bands and sarcomeres in YM100 were obviously increased(P<0.05).The expression of myf5,myog and myhc exhibited a significant upward trend with the increase of dietary TM(P<0.05),which promoted fiber density,length of sarcomere and texture of grass carp muscle.According to the results of metabolomics,the arachidonate(ARA)and eicosapentaenoic acid(EPA)were notably elevated in YM30 and YM100,which indicated that the improvement of flesh quality of grass carp may contribute to the dietary TM influence on muscle lipid metabolism,especially the polyunsaturated fatty acids.In conclusion,TM can completely replace dietary soybean meal and improve the nutritional value of grass carp.展开更多
This paper evaluates the efficiency of the SARFIMA model at forecasting high-frequency long memory series with especially long periods. Three other models, the ARFIMA, ARMA and PAR models, are also included to compare...This paper evaluates the efficiency of the SARFIMA model at forecasting high-frequency long memory series with especially long periods. Three other models, the ARFIMA, ARMA and PAR models, are also included to compare their forecasting performances with that of the SARFIMA model. For the artificial SARFIMA series, if the correct parameters are used for estimating and forecasting, the model performs as well as the other three models. However, if the parameters obtained by the WHI estimation are used, the performance of the SARFIMA model falls far behind that of the other models. For the empirical intraday volume series, the SARFIMA model produces the worst performance of all of the models, and the ARFIMA model performs best. The ARMA and PAR models perform very well both for the artificial series and for the intraday volume series. This result indicates that short memory models are competent in forecasting periodic long memory series.展开更多
A 90-day feeding trial was conducted to assess the effects of black soldier fly larvae meal(BSFLM)as a replacement for soybean meal(SM)on growth performance and flesh quality of grass carp.A total of 420grass carp(299...A 90-day feeding trial was conducted to assess the effects of black soldier fly larvae meal(BSFLM)as a replacement for soybean meal(SM)on growth performance and flesh quality of grass carp.A total of 420grass carp(299.93±0.85 g)were randomly divided into 7 groups(triplicate)and fed 7 diets with SM substitution of 0%(SM,control),15%(BSFLM15),30%(BSFLM30),45%(BSFLM45),60%(BSFLM60),75%(BSFLM75)and 100%(BSFLM100)by BSFLM.The growth performance of grass carp in the BSFLM75 and BSFLM100 groups were significantly lower compared to other groups(P<0.05).The mid-gut villus height was the lowest in the BSFLM100 group(P<0.05).Muscle nutritional value was improved due to increased DHA(docosahexaenoic acid),EPA(eicosapentaenoic acid),total HUFA(highly unsaturated fatty acids)and glycine levels,and reached the optimum in the BSFLM100 group(P<0.05).According to the results of principal component analysis and weight analysis of muscle texture and body color,all the BSFLM diets except BSFLM15 could improve muscle texture and body color and reached the optimum level in the BSFLM100 group.Muscle drip loss and hypoxanthine content were the lowest and muscle antioxidant capacity was the highest in the BSFLM75 group,and water-and salt-soluble protein contents reached the optimum level in the BSFLM60 group(P<0.05).Dietary BSFLM significantly reduced muscle fiber area and diameter,and increased muscle fiber density and the proportion of small fiber(diameter<20μm)(P<0.05).Additionally,sarcomere lengths in the BSFLM75 and BSFLM100 groups were significantly higher than that in the SM group(P<0.05).The m RNA relative expression levels of Myo D,Myf5,My HC and FGF6b were remarkably up-regulated at an appropriate dietary BSFLM level(P<0.05).In conclusion,BSFLM could replace up to 60%SM without an adverse effect on growth performance and improve the flesh quality of grass carp.The optimum levels of dietary BSFLM were 71.0 and 69.1 g/kg diet based on the final body weight and feed conversion ratio.The flesh quality was optimal when dietary SM was completely replaced with BSFLM(227 g/kg diet).展开更多
The microscopic morphology of electromagnetic wave absorbers influences the multiple reflections of electromagnetic waves and impedance matching,determining the absorption properties.Herein,the urchin-shaped bimetalli...The microscopic morphology of electromagnetic wave absorbers influences the multiple reflections of electromagnetic waves and impedance matching,determining the absorption properties.Herein,the urchin-shaped bimetallic nickel-cobalt oxide/carbon(NiCo_(2)O_(4)/C)composites are prepared via a hy-drothermal route,whose absorption properties are investigated by different morphologies regulated by changing calcination temperature.A minimum reflection loss(RL_(min))of-75.26 dB is achieved at a match-ing thickness of 1.5 mm,and the effective absorption bandwidth(EAB)of 8.96 GHz is achieved at 2 mm.Multi-advantages of the synthesized NiCo_(2)O_(4)/C composites contribute to satisfactory absorption proper-ties.First,the interweaving of the needle-like structures increases the opportunities for scattering and multiple reflections of incident electromagnetic waves,and builds up a conductive network to facilitate the enhancement of conductive losses.Second,the carbon component in the NiCo_(2)O_(4)/C composites en-hances the interfacial polarization and reduces the density of the absorber.Besides,generous oxygen va-cancy defects are introduced into the NiCo_(2)O_(4)/C composites,which induces defect polarization and dipole polarization.In summary,the ternary coordination of components,defects and morphology led to out-standing electromagnetic wave absorption,which lightened the path for improving the electromagnetic wave absorption property and enriching the family of NiCo_(2)O_(4) absorbers with excellent performance.展开更多
Based on the minimum loss probability criterion,this paper discusses the optimal strategy in multi-asset liquidation.First,we give the framework of the multi-asset liquidation problem and obtain the boundary condition...Based on the minimum loss probability criterion,this paper discusses the optimal strategy in multi-asset liquidation.First,we give the framework of the multi-asset liquidation problem and obtain the boundary conditions of the optimal liquidation strategy under the assumption of linear price impact functions and transform the multi-asset liquidation problem into the portfolio liquidation problem.On this basis,the asymptotic solution and numerical solution of the optimal liquidation strategy are obtained.Then,we simulate the trajectories of the optimal liquidation strategy and analyze the effects of parameters changes.展开更多
Effects of photoionisation on the development and electron runaway of the initial discharge in atmospheric air under nanosecond pulse voltage were studied via twodimensional particle-in-cell/Monte Carlo collision simu...Effects of photoionisation on the development and electron runaway of the initial discharge in atmospheric air under nanosecond pulse voltage were studied via twodimensional particle-in-cell/Monte Carlo collision simulations.It was found that photoionisation has little effect at the beginning of the initial discharge.However,as the discharge channel gradually develops towards the anode,photoionisation shows greater impacts on the morphology of discharge but has little influence on the velocity of discharge development.Photoionisation does not appear to have a decisive effect on the growth trend of the highest energy of runaway electrons,but it does affect the change rate of the highest energy and overall distribution of electron energy,resulting in a higher proportion of energetic electrons.The difference in the distributions of the electron energy between the two cases,with and without considering photoionisation,can be attributed to the impact of photoionisation on the discharge morphology,which in turn distorted the electric field.The spatial density distributions of the electrons produced by photoionisation further explained the differences.The authors’results explicitly demonstrate the influence of photoionisation on the development and the electron runaway of the initial discharge under nanosecond pulse voltage,which provides more comprehensive knowledge for the atmospheric air gap nanosecond pulse discharge physics.展开更多
In order to maintain the optimal operating temperature of the battery surface and meet the demand for thermal storage technology,battery thermal management system based on phase change materials has attracted increasi...In order to maintain the optimal operating temperature of the battery surface and meet the demand for thermal storage technology,battery thermal management system based on phase change materials has attracted increasing interest.In this work,a kind of core-shell structured microcapsule was synthesized by an in-situ polymerization,where paraffin was used as the core,while methanol was applied to mod-ify the melamine-formaldehyde shell to reduce toxicity and improve thermal stability.Moreover,three different types of heat conductive fillers with the same content of 10 wt.%,i.e.,nano-Al_(2)O_(3),nano-ZnO and carbon nanotubes were added,generating composites.The microcapsules were uniform,and were not affected by the thermal fillers,which were evenly dispersed around.The composite sample with carbon nanotubes(10 wt.%)showed the highest thermal conductivity of 0.50 W/(m K)and latent heat of 139.64 J/g.Furthermore,according to the leakage testing and battery charge/discharge experiments,compared with Al_(2)O_(3)and ZnO,the addition of carbon nanotubes remarkably enhances the heat storage ability as latent heat from 126.98 J/g for the prepared sample with Al_(2)O_(3)and 125.86 J/g for the one with ZnO,then to 139.64 J/g,as well as dissipation performance as a cooling effect by decreasing the sur-face temperature of battery from 2%to 12%of microcapsule,composite sample with carbon nanotubes presents a broad application prospect in battery thermal management system and energy storage field.展开更多
Structural optimization of ionomers is an effective strategy for achieving high-performance proton ex-change membranes(PEMs)under low relative humidity(RH)conditions.In this study,sulfonimide group and trifluoromethan...Structural optimization of ionomers is an effective strategy for achieving high-performance proton ex-change membranes(PEMs)under low relative humidity(RH)conditions.In this study,sulfonimide group and trifluoromethanesulfonate acid(TFSA)ionic liquids were introduced to the perfluorosulfonic acid(PFSA)side chain,resulting in polymer membranes with varying chain lengths(i.e.,PFC_(2)-TF-SI,PFC_(4)-TF-SI,and PFC_(5)-TF-SI).This dual proton-conducting structure extended the length of the hydrophilic side chain and enhanced the hydrophobic-hydrophilic phase separation,aiding in the formation of proton transport channels.Notably,the proton conductivity of PFC_(5)-TF-SI and PFC_(2)-TF-SI membranes reached 7.1 and 10.6 mS/cm at 30%RH and 80°C,respectively,which were approximately 29.1%and 92.7%higher than that of the pristine PFC_(5)-SA membrane(5.5 mS/cm).Furthermore,the maximum power density of the PFC_(5)-TF-SI and PFC_(2)-TF-SI membranes from the built single fuel cell achieved 649 and 763 mW/cm 2 at 30%RH and 80°C,respectively,which were higher than that of the pristine PFC_(5)-SA membrane(567 mW/cm 2)by about 14.5%and 34.6%,respectively.Thus,this study provides a strategy for PEM design under low RH conditions.展开更多
基金The authors acknowledge the financial support from the National Natural Science Foundation of China(Nos.52073224,32201491)the Textile Vision Basic Research Program of China(No.J202110)+3 种基金the Scientific Research Project of Shaanxi Provincial Education Department,China(No.22JC035)the Advanced Manufacturing Technology Program of Xi’an Science and Technology Bureau,China(No.21XJZZ0019)the Research Fund for the Doctoral Program of Xi’an Polytechnic University(No.BS202053)the Youth Innovation Team of Shaanxi Universities and Institute of Flexible electronics and Intelligent Textile.
文摘MXene,a transition metal carbide/nitride,has been prominent as an ideal electrochemical active material for supercapacitors.However,the low MXene load limits its practical applications.As environmental concerns and sustainable development become more widely recognized,it is necessary to explore a greener and cleaner technology to recycle textile by-products such as cotton.The present study proposes an effective 3D fabrication method that uses MXene to fabricate waste denim felt into ultralight and flexible supercapacitors through needling and carbonization.The 3D structure provided more sites for loading MXene onto Z-directional fiber bundles,resulting in more efficient ion exchange between the electrolyte and electrodes.Furthermore,the carbonization process removed the specific adverse groups in MXenes,further improving the specific capacitance,energy density,power density and electrical conductivity of supercapacitors.The electrodes achieve a maximum specific capacitance of 1748.5 mF cm-2 and demonstrate remarkable cycling stability maintaining more than 94%after 15,000 galvanostatic charge/discharge cycles.Besides,the obtained supercapacitors present a maximum specific capacitance of 577.5 mF cm^(-2),energy density of 80.2μWh cm^(-2)and power density of 3 mW cm^(-2),respectively.The resulting supercapacitors can be used to develop smart wearable power devices such as smartwatches,laying the foundation for a novel strategy of utilizing waste cotton in a high-quality manner.
基金Project supported by the National Key R&D Program of China(Grant Nos.2018YFA0306102 and 2018YFA0306703)the National Natural Science Foundation of China(Grant No.61474014)+1 种基金the Sichuan Science and Technology Program,China(Grant No.2019YJ0202)the University Program for Elaborate Courses of Postgraduates。
文摘The growth of γ-In_(2)Se_(3) thin films on mica by molecular beam epitaxy is studied. Single-crystalline γ-In_(2)Se_(3) is achieved at a relatively low growth temperature. An ultrathin β-In_(2)Se_(3) buffer layer is observed to nucleate and grow through a process of self-organization at initial deposition, which facilitates subsequent monolithic epitaxy of single-crystallineγ-In_(2)Se_(3) at low temperature. Strong room-temperature photoluminescence and moderate optoelectronic response are observed in the achieved γ-In_(2)Se_(3) thin films.
文摘Chronic disease is an important factor that affect the health of elderly people. We analyzed the 2006 and 2010 data from the Chinese Urban and Rural Elderly Population Surveys, which are nationally representative surveys of elderly people aged 60 years and above. We found that there existed a typical power-law distribution for the rates of different numbers of chronic diseases among elderly Chinese people. A Kolmogorov-Smirnov test indicated that the result was robust, and the power exponents were approximately ?2.5. In addition, a paired t-test was conducted, which demonstrated that the rates of different numbers of chronic diseases did not have significant urban-rural differences, time differences or gender differences.
文摘This paper reviews the original achievements and advances regarding the field effect transistor(FET) fabricated from one of the most studied transition metal dichalcogenides: two-dimensional Mo S2. Not like graphene, which is highlighted by a gapless Dirac cone band structure, Monolayer Mo S2 is featured with a 1.9 e V gapped direct energy band thus facilitates convenient electronic and/or optoelectronic modulation of its physical properties in FET structure. Indeed,many Mo S2 devices based on FET architecture such as phototransistors, memory devices, and sensors have been studied and extraordinary properties such as excellent mobility, ON/OFF ratio, and sensitivity of these devices have been exhibited. However, further developments in FET device applications depend a lot on if novel physics would be involved in them. In this review, an overview on advances and developments in the Mo S2-based FETs are presented. Engineering of Mo S2-based FETs will be discussed in details for understanding contact physics, formation of gate dielectric, and doping strategies. Also reported are demonstrations of device behaviors such as low-frequency noise and photoresponse in Mo S2-based FETs, which is crucial for developing electronic and optoelectronic devices.
基金This research was financially supported by National Key R&D Program of China(2019YFD0900200).
文摘In order to find viable alternative protein sources for aquaculture,we evaluated the effect of partial or complete replacement of dietary soybean meal with yellow mealworm(TM)on the flesh quality of grass carp.In this study,180 grass carp(511.85±0.25 g)were fed 3 experimental diets in which 0%(CN),30%(YM30)and 100%(YM100)dietary soybean meal was replaced by TM for 90 d.The results showed that growth performance,biological parameters and serum antioxidant capacity of grass carp were not affected by dietary TM(P>0.05).Both muscle and whole body crude protein were obviously promoted with the increase of dietary TM(P<0.05),and the concentration of heavy metal in muscle was not influenced(P>0.05),indicating that food safety was not influenced by TM.Dietary TM improved muscle textural characteristics by elevating adhesiveness,springiness and chewiness in YM100(P<0.05).In addition,the muscle tenderness was significantly increased by declining the shear force(P<0.05).The muscle fiber density in YM30&YM100 and length of dark bands and sarcomeres in YM100 were obviously increased(P<0.05).The expression of myf5,myog and myhc exhibited a significant upward trend with the increase of dietary TM(P<0.05),which promoted fiber density,length of sarcomere and texture of grass carp muscle.According to the results of metabolomics,the arachidonate(ARA)and eicosapentaenoic acid(EPA)were notably elevated in YM30 and YM100,which indicated that the improvement of flesh quality of grass carp may contribute to the dietary TM influence on muscle lipid metabolism,especially the polyunsaturated fatty acids.In conclusion,TM can completely replace dietary soybean meal and improve the nutritional value of grass carp.
文摘This paper evaluates the efficiency of the SARFIMA model at forecasting high-frequency long memory series with especially long periods. Three other models, the ARFIMA, ARMA and PAR models, are also included to compare their forecasting performances with that of the SARFIMA model. For the artificial SARFIMA series, if the correct parameters are used for estimating and forecasting, the model performs as well as the other three models. However, if the parameters obtained by the WHI estimation are used, the performance of the SARFIMA model falls far behind that of the other models. For the empirical intraday volume series, the SARFIMA model produces the worst performance of all of the models, and the ARFIMA model performs best. The ARMA and PAR models perform very well both for the artificial series and for the intraday volume series. This result indicates that short memory models are competent in forecasting periodic long memory series.
基金supported by the National Key R&D Program of China(2019YFD0900200)in finance。
文摘A 90-day feeding trial was conducted to assess the effects of black soldier fly larvae meal(BSFLM)as a replacement for soybean meal(SM)on growth performance and flesh quality of grass carp.A total of 420grass carp(299.93±0.85 g)were randomly divided into 7 groups(triplicate)and fed 7 diets with SM substitution of 0%(SM,control),15%(BSFLM15),30%(BSFLM30),45%(BSFLM45),60%(BSFLM60),75%(BSFLM75)and 100%(BSFLM100)by BSFLM.The growth performance of grass carp in the BSFLM75 and BSFLM100 groups were significantly lower compared to other groups(P<0.05).The mid-gut villus height was the lowest in the BSFLM100 group(P<0.05).Muscle nutritional value was improved due to increased DHA(docosahexaenoic acid),EPA(eicosapentaenoic acid),total HUFA(highly unsaturated fatty acids)and glycine levels,and reached the optimum in the BSFLM100 group(P<0.05).According to the results of principal component analysis and weight analysis of muscle texture and body color,all the BSFLM diets except BSFLM15 could improve muscle texture and body color and reached the optimum level in the BSFLM100 group.Muscle drip loss and hypoxanthine content were the lowest and muscle antioxidant capacity was the highest in the BSFLM75 group,and water-and salt-soluble protein contents reached the optimum level in the BSFLM60 group(P<0.05).Dietary BSFLM significantly reduced muscle fiber area and diameter,and increased muscle fiber density and the proportion of small fiber(diameter<20μm)(P<0.05).Additionally,sarcomere lengths in the BSFLM75 and BSFLM100 groups were significantly higher than that in the SM group(P<0.05).The m RNA relative expression levels of Myo D,Myf5,My HC and FGF6b were remarkably up-regulated at an appropriate dietary BSFLM level(P<0.05).In conclusion,BSFLM could replace up to 60%SM without an adverse effect on growth performance and improve the flesh quality of grass carp.The optimum levels of dietary BSFLM were 71.0 and 69.1 g/kg diet based on the final body weight and feed conversion ratio.The flesh quality was optimal when dietary SM was completely replaced with BSFLM(227 g/kg diet).
基金financially supported by the National Natu-ral Science Foundation of China(No.52207249)the Natural Sci-ence Foundation of Shandong Province(No.ZR2022ME089)+2 种基金the research program of Top Talent Project of Yantai University(No.1115/2220001)the Yantai Basic Research Project(No.2022JCYJ04)the Science Fund of Shandong Laboratory of Advanced Ma-terials and Green Manufacturing(No.AMGM2021F11).The au-thors would like to thank the Deanship of Scientific Research at Umm Al-Qura University for supporting this work by Grant Code:22UQU4320141DSR72.
文摘The microscopic morphology of electromagnetic wave absorbers influences the multiple reflections of electromagnetic waves and impedance matching,determining the absorption properties.Herein,the urchin-shaped bimetallic nickel-cobalt oxide/carbon(NiCo_(2)O_(4)/C)composites are prepared via a hy-drothermal route,whose absorption properties are investigated by different morphologies regulated by changing calcination temperature.A minimum reflection loss(RL_(min))of-75.26 dB is achieved at a match-ing thickness of 1.5 mm,and the effective absorption bandwidth(EAB)of 8.96 GHz is achieved at 2 mm.Multi-advantages of the synthesized NiCo_(2)O_(4)/C composites contribute to satisfactory absorption proper-ties.First,the interweaving of the needle-like structures increases the opportunities for scattering and multiple reflections of incident electromagnetic waves,and builds up a conductive network to facilitate the enhancement of conductive losses.Second,the carbon component in the NiCo_(2)O_(4)/C composites en-hances the interfacial polarization and reduces the density of the absorber.Besides,generous oxygen va-cancy defects are introduced into the NiCo_(2)O_(4)/C composites,which induces defect polarization and dipole polarization.In summary,the ternary coordination of components,defects and morphology led to out-standing electromagnetic wave absorption,which lightened the path for improving the electromagnetic wave absorption property and enriching the family of NiCo_(2)O_(4) absorbers with excellent performance.
基金Acknowledgements This work is supported by the National Natural Science Foundation of China （Nos. 11104010, 61474014, and 51272038）, Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics （No. 20120910）, and the National Basic Research Program of China （No. 2013CB933301）.
文摘在超点阵的热运输被各种各样的散布声子的过程管理。为在 chalcogenide 超点阵提取异种接口的散布声子的贡献，单人赛水晶的双性人 <sub>2</sub > Se <sub>3</sub>/In<sub>2</sub > 有最小化的缺点的 Se <sub>3</sub>(BS/IS ) 超点阵被分子的横梁取向附生在 fluorophlogopite 云母上准备。BS/IS 超点阵的跨飞机的进行热的性质被表明精确取决于时期厚度和超点阵的成分，在在热传导性的最小显示一条转线路从的地方对在超点阵的像波浪的声子运输像粒子。BS/IS 超点阵的热传导性的最小比内在的 BS 电影的低将近一个数量级。
基金the National Natural Science Foundation of China(Grant No.71671017).
文摘Based on the minimum loss probability criterion,this paper discusses the optimal strategy in multi-asset liquidation.First,we give the framework of the multi-asset liquidation problem and obtain the boundary conditions of the optimal liquidation strategy under the assumption of linear price impact functions and transform the multi-asset liquidation problem into the portfolio liquidation problem.On this basis,the asymptotic solution and numerical solution of the optimal liquidation strategy are obtained.Then,we simulate the trajectories of the optimal liquidation strategy and analyze the effects of parameters changes.
基金National Natural Science Foundation of China,Grant/Award Number:52077117Tsinghua University Initiative Scientific Research ProgramState Key Laboratory of Power System and Generation Equipment,Grant/Award Number:SKLD21M06。
文摘Effects of photoionisation on the development and electron runaway of the initial discharge in atmospheric air under nanosecond pulse voltage were studied via twodimensional particle-in-cell/Monte Carlo collision simulations.It was found that photoionisation has little effect at the beginning of the initial discharge.However,as the discharge channel gradually develops towards the anode,photoionisation shows greater impacts on the morphology of discharge but has little influence on the velocity of discharge development.Photoionisation does not appear to have a decisive effect on the growth trend of the highest energy of runaway electrons,but it does affect the change rate of the highest energy and overall distribution of electron energy,resulting in a higher proportion of energetic electrons.The difference in the distributions of the electron energy between the two cases,with and without considering photoionisation,can be attributed to the impact of photoionisation on the discharge morphology,which in turn distorted the electric field.The spatial density distributions of the electrons produced by photoionisation further explained the differences.The authors’results explicitly demonstrate the influence of photoionisation on the development and the electron runaway of the initial discharge under nanosecond pulse voltage,which provides more comprehensive knowledge for the atmospheric air gap nanosecond pulse discharge physics.
基金supported by the National Natural Science Foundation of China(Nos.12202410 and 51906238)the China Postdoctoral Science Foundation(No.2023M733935)+4 种基金the Natural Science Foundation of Hunan Province(No.2023JJ40726)the Research Project Supported by the Shanxi Scholarship Council of China(No.2022-139)the Natural Science Foundation of Shanxi Province(Nos.20210302123017 and 2023recipient Changcheng Liu)the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(No.20220012)the Changsha Municipal Natural Science Foundation(No.kq2208277).
文摘In order to maintain the optimal operating temperature of the battery surface and meet the demand for thermal storage technology,battery thermal management system based on phase change materials has attracted increasing interest.In this work,a kind of core-shell structured microcapsule was synthesized by an in-situ polymerization,where paraffin was used as the core,while methanol was applied to mod-ify the melamine-formaldehyde shell to reduce toxicity and improve thermal stability.Moreover,three different types of heat conductive fillers with the same content of 10 wt.%,i.e.,nano-Al_(2)O_(3),nano-ZnO and carbon nanotubes were added,generating composites.The microcapsules were uniform,and were not affected by the thermal fillers,which were evenly dispersed around.The composite sample with carbon nanotubes(10 wt.%)showed the highest thermal conductivity of 0.50 W/(m K)and latent heat of 139.64 J/g.Furthermore,according to the leakage testing and battery charge/discharge experiments,compared with Al_(2)O_(3)and ZnO,the addition of carbon nanotubes remarkably enhances the heat storage ability as latent heat from 126.98 J/g for the prepared sample with Al_(2)O_(3)and 125.86 J/g for the one with ZnO,then to 139.64 J/g,as well as dissipation performance as a cooling effect by decreasing the sur-face temperature of battery from 2%to 12%of microcapsule,composite sample with carbon nanotubes presents a broad application prospect in battery thermal management system and energy storage field.
基金This work was financially supported by the National Key Re-search and Development Program of China(No.2022YFB4003500)the National Natural Science Foundation of China(No.T2241003)+2 种基金the Key R&D Project of Hubei Province,China(No.2021AAA006)the National Natural Science Foundation of China(No.52202009)The researchers would like to acknowledge Deanship of Scientific Research,Taif University for funding this work.HA is thankful to the Deanship of Scientific Research at Najran University for funding this work,under the Research Groups Funding program grant code(NU/RG/SERC/12/10).
文摘Structural optimization of ionomers is an effective strategy for achieving high-performance proton ex-change membranes(PEMs)under low relative humidity(RH)conditions.In this study,sulfonimide group and trifluoromethanesulfonate acid(TFSA)ionic liquids were introduced to the perfluorosulfonic acid(PFSA)side chain,resulting in polymer membranes with varying chain lengths(i.e.,PFC_(2)-TF-SI,PFC_(4)-TF-SI,and PFC_(5)-TF-SI).This dual proton-conducting structure extended the length of the hydrophilic side chain and enhanced the hydrophobic-hydrophilic phase separation,aiding in the formation of proton transport channels.Notably,the proton conductivity of PFC_(5)-TF-SI and PFC_(2)-TF-SI membranes reached 7.1 and 10.6 mS/cm at 30%RH and 80°C,respectively,which were approximately 29.1%and 92.7%higher than that of the pristine PFC_(5)-SA membrane(5.5 mS/cm).Furthermore,the maximum power density of the PFC_(5)-TF-SI and PFC_(2)-TF-SI membranes from the built single fuel cell achieved 649 and 763 mW/cm 2 at 30%RH and 80°C,respectively,which were higher than that of the pristine PFC_(5)-SA membrane(567 mW/cm 2)by about 14.5%and 34.6%,respectively.Thus,this study provides a strategy for PEM design under low RH conditions.
