This paper reports the kinetic process of Ag ion exchange for the polycrystalline Na-β'-Al2O3.The interdiffusion coefficients in the process of Ag+ and Na+ ion exchange have been calculated with an 'one dimen...This paper reports the kinetic process of Ag ion exchange for the polycrystalline Na-β'-Al2O3.The interdiffusion coefficients in the process of Ag+ and Na+ ion exchange have been calculated with an 'one dimensional double side diffusion model'. Microstructures of the samples were observed and analysed by XRD, EMPA, SEM. The results of the conductivity measurements for samples with Na+, Ag+ and Na+-Ag+ mobile ions are presented and explained展开更多
The apatite-type lanthanum silicates with formula La9.33Si6O26 are prepared by sol-gel process. The homogeneity of the sol affected by pH value of the solution is investigated. The viscosity of the sols slightly incre...The apatite-type lanthanum silicates with formula La9.33Si6O26 are prepared by sol-gel process. The homogeneity of the sol affected by pH value of the solution is investigated. The viscosity of the sols slightly increases first and then increases abruptly because the predominant reaction mechanism changes from hydrolysis reaction to condensation reaction. In addition, the onset time of the increase for the viscosity shortens from pH 1 to pH 4. The gelation time decreases with increasing pH of the solution. Therefore, the pH of the sols should be less than 4 to form gel. The sol with initial pH 2 shows maximum value of zeta potential and maximum stability. For the sample with initial pH 2, pure apatite-type lanthanum silicates La9.33Si6O26 have been successfully prepared after the dried gel is calcined at 1 000 ℃. In addition, this sample sintered at 1 550 ℃ exhibits the highest ionic conductivity. The activation energies are all less than 0.90 eV.展开更多
Perfl uorosulfonic acid/ceramic nanocomposite membranes were investigated as electrolytes for polymer electrolyte membrane fuel cell applications under low relative humidity. Different nanosized ceramics（SiO2, ZrO2, ...Perfl uorosulfonic acid/ceramic nanocomposite membranes were investigated as electrolytes for polymer electrolyte membrane fuel cell applications under low relative humidity. Different nanosized ceramics（SiO2, ZrO2, TiO2） with diameters in the range of 2-6 nm were synthesized in situ in Nafion solution through a sol-gel process and the formed nanosized ceramics were well-dispersed in the solution.The nanocomposite membranes were formed through a casting process. The nanocomposite membrane showes enhanced water retention ability and improved proton conductivity compared to those of pure Nafi on membrane. The mechanical strength of the formed nanocomposite membranes is slightly less than that of pure Nafi on membrane. The experimental results demonstrate that the polymer ceramic nanocompsite membranes are potential electrolyte for fuel cells operating at elevated temperature.展开更多
A rotary-concentrating device for thermal conduction is constructed to control and guide thermal energy transmitting in elastic plates.The designed device has the ability of concentrating for thermal conduction and co...A rotary-concentrating device for thermal conduction is constructed to control and guide thermal energy transmitting in elastic plates.The designed device has the ability of concentrating for thermal conduction and controlling the processes of thermal diffusion in a plate.The multilayered isotropic material properties of the rotary-concentrating device are derived based on the transformation and rotary medium method and a rotation parameter to control the thermal diffusion process is introduced.The efficiency of the rotary-concentrating device for thermal conduction is verified.Stability of temperature fields in a plate with the rotary-concentrating device is analyzed to study the performance of rotary-concentrating.Numerical examples show that the constructed rotary-concentrating device for thermal conduction can effectively rotate and focus on the thermal energy into the device for a wide range of diffusion temperatures,which can enhance the thermal conduction.Therefore,this study can provide a theoretical support for potential applications in fields of energy harvesting and thermal conduction control.展开更多
Due to the volume conduction,electroencephalogram（EEG） gives a rather blurred image of brain activities. It is a challenge for generating satisfactory performance with EEG. This paper studies the multiple areas fusi...Due to the volume conduction,electroencephalogram（EEG） gives a rather blurred image of brain activities. It is a challenge for generating satisfactory performance with EEG. This paper studies the multiple areas fusion of EEG classifiers to improve the motor imagery EEG classification performance. Two feature extraction methods are employed to extract the feature from three different areas of EEG. One is power spectral density（PSD）, and the other is common spatial patterns（CSP）. Classifiers are designed based on the well-known linear discrimination analysis（LDA）. The fusion of the individual classifiers is realized by means of the Choquet fuzzy integral. It is demonstrated that the proposed method comes with better performance compared with the individual classifier.展开更多
CONSPECTUS:Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymerbased additive manufacturing(AM),driven by the growing demand for multifunctional 3D-printi...CONSPECTUS:Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymerbased additive manufacturing(AM),driven by the growing demand for multifunctional 3D-printing.While several AM techniques have been adapted to process conductive composites,Digital Light Processing(DLP)stands out for its high-resolution and fast-curing capabilities.However,it poses a central limitation:the requirement for optical transparency in the printing resin,which is compromised by the incorporation of conventional conductive fillers.This Account highlights the advances in overcoming three fundamental challenges in the field:(i)How can conductive nanocomposites be printed by DLP without compromising resolution?(ii)How can high electrical conductivity be achieved at low filler content?(iii)What is the origin of anisotropic conductivity in printed objects,and how can it be mitigated?To address the first question,the authors introduced a strategy based on UV-transparent precursors,specifically monolayer graphene oxide(GO).GO’s minimal UV absorption allows its use as a printable nanofiller at weight fractions up to 0.35 vol%,preserving the curing depth and optical clarity required for DLP.Postprinting thermal reduction of GO into reduced graphene oxide(rGO)yields nanocomposites with conductivities up to 10^(-2)S m^(-1)-comparable to conventional carbon nanotube(CNT)systems but achieved without high UV attenuation.To tackle the second question,the authors explored the use of single-walled carbon nanotubes(SWCNTs),which,due to their high aspect ratio and intrinsic conductivity,exhibit ultralow percolation thresholds(<0.01 vol%).At these concentrations,UV interference is negligible.However,the need for surfactant-assisted dispersion introduces contact resistance,limiting conductivity.To overcome this,this Account presents a hybrid formulation in which GO serves as both dispersant and conductive additive,enhancing internanotube contacts upon reduction.This approach achieves conductivities up to 0.3 S m^(-1),with a total filler content below 0.15 vol%,representing a significant leap in performance without sacrificing resolution.To resolve the third question regarding electrical anisotropy,the study employs polarized Raman spectroscopy,conclusively showing that nanotube alignment is not responsible for the observed directional conductivity differences.Instead,the anisotropy arises from interfacial contact resistance between printed layers,an intrinsic artifact of the layer-by-layer DLP process.Mitigation strategies such as delayed UV curing and temperature-controlled printing were shown to significantly reduce this resistance and improve isotropy.Beyond addressing these scientific questions,this Account highlights the practical impact of these materials.Notably,hybrid nanocomposites exhibited strong potential in microwave absorption,reaching broadband reflection losses below-10 dB at low filler loadings,due to combined ohmic and dielectric losses.These outcomes demonstrate that high-resolution,fast DLP printing of conductive materials is not only feasible but also tunable and scalable for applications in sensors,soft robotics,and electromagnetic shielding.By answering these key questions,the work establishes a foundation for the rational design of printable conductive nanocomposites,balancing optical compatibility,conductivity,and mechanical precision-paving the way for next-generation functional devices fabricated through vat photopolymerization.展开更多
Long-term bioelectric potential recording requires highly reliable wearable dry electrodes.Laser-induced graphene(LIG)dry electrodes on polyimide(PI)films are difficult to conform to the skin due to the non-stretchabi...Long-term bioelectric potential recording requires highly reliable wearable dry electrodes.Laser-induced graphene(LIG)dry electrodes on polyimide(PI)films are difficult to conform to the skin due to the non-stretchability and low flexibility of PI films.As a result,high interface impedance and motion artifacts can occur during body movements.Transferring LIG to flexible substrates such as polydimethylsiloxane(PDMS)and Ecoflex allows for stretchability and flexibility.However,the transfer process produces a significant loss of conductivity destroying the structural function and electron conduction properties of the LIG.We found robust physical and chemical bonding effects between LIG and styrene-ethylene-butylene-styrene(SEBS)thermoplastic elastomer substrates and proposed a simple and robust low-conductivity loss transfer technique.Successfully embedded LIG onto SEBS to obtain high stretchability,high flexibility,low conductivity losses.Electrophoretic deposition(EPD)of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid(PEDOT:PSS)on LIG forms an ultrathin polymer conductive coating.The deposition thickness of the conductive polymer is adjusted by controlling the EPD deposition time to achieve optimal conductivity and chemical stability.SEBS/LIG/PEDOT:PSS(SLPP)dry electrodes have high conductivity(114Ω/Sq),stretchability(300%)and reliability(30%stretch,15,000 cycles),low electrode-skin impedance(14.39 kΩ,10 Hz).The detected biopotential signal has a high signal-to-noise ratio(SNR)of 35.78 dB.Finally,the feasibility of SLPP dry electrodes for long-term biopotential monitoring and biopotential-based human-machine interface control of household appliances was verified.展开更多
A stochastic model of chemical reaction-heat conduction-diffusion for a one-dimensional gaseous system under Dirichlet or zero-fluxes boundary conditions is proposed in this paper.Based on this model,we extend the the...A stochastic model of chemical reaction-heat conduction-diffusion for a one-dimensional gaseous system under Dirichlet or zero-fluxes boundary conditions is proposed in this paper.Based on this model,we extend the theory of the broadening exponent of critical fluctuations to cover the chemical reaction-heat conduction coupling systems as an asymptotic property of the corresponding Markovian master equation(ME),and establish a valid stochastic thermodynamics for such systems.As an illustration,the non-isothermal and inhomogeneous Schl-gl model is explicitly studied.Through an order analysis of the contributions from both the drift and diffusion to the evolution of the probability distribution in the corresponding Fokker-Planck equation(FPE)in the approach to bifurcation,we have identified the critical transition rule for the broadening exponent of the fluctuations due to the coupling between chemical reaction and heat conduction.It turns out that the dissipation induced by the critical fluctuations reaches a deterministic level,leading to a thermodynamic effect on the nonequilibrium physico-chemical processes.展开更多
文摘This paper reports the kinetic process of Ag ion exchange for the polycrystalline Na-β'-Al2O3.The interdiffusion coefficients in the process of Ag+ and Na+ ion exchange have been calculated with an 'one dimensional double side diffusion model'. Microstructures of the samples were observed and analysed by XRD, EMPA, SEM. The results of the conductivity measurements for samples with Na+, Ag+ and Na+-Ag+ mobile ions are presented and explained
文摘The apatite-type lanthanum silicates with formula La9.33Si6O26 are prepared by sol-gel process. The homogeneity of the sol affected by pH value of the solution is investigated. The viscosity of the sols slightly increases first and then increases abruptly because the predominant reaction mechanism changes from hydrolysis reaction to condensation reaction. In addition, the onset time of the increase for the viscosity shortens from pH 1 to pH 4. The gelation time decreases with increasing pH of the solution. Therefore, the pH of the sols should be less than 4 to form gel. The sol with initial pH 2 shows maximum value of zeta potential and maximum stability. For the sample with initial pH 2, pure apatite-type lanthanum silicates La9.33Si6O26 have been successfully prepared after the dried gel is calcined at 1 000 ℃. In addition, this sample sintered at 1 550 ℃ exhibits the highest ionic conductivity. The activation energies are all less than 0.90 eV.
基金Funded by the Postdoctoral Science Foundation of China(2013M540610)the Hubei Province Scientific Research Projects(D20131601)
文摘Perfl uorosulfonic acid/ceramic nanocomposite membranes were investigated as electrolytes for polymer electrolyte membrane fuel cell applications under low relative humidity. Different nanosized ceramics（SiO2, ZrO2, TiO2） with diameters in the range of 2-6 nm were synthesized in situ in Nafion solution through a sol-gel process and the formed nanosized ceramics were well-dispersed in the solution.The nanocomposite membranes were formed through a casting process. The nanocomposite membrane showes enhanced water retention ability and improved proton conductivity compared to those of pure Nafi on membrane. The mechanical strength of the formed nanocomposite membranes is slightly less than that of pure Nafi on membrane. The experimental results demonstrate that the polymer ceramic nanocompsite membranes are potential electrolyte for fuel cells operating at elevated temperature.
基金Project supported by the National Natural Science Foundation of China(Grant No.12102150)the Natural Science Foundation of Jiangsu Province+3 种基金China(Grant Nos.BK20200884 and BK20201414)the Natural Science Foundation of Colleges and Universities in Jiangsu Province,China(Grant No.20KJB130004)China Postdoctoral Science Foundation(Grant No.2021M702444)the Jiangsu’s Mass Entrepreneurship and Innovation Program of Jiangsu Province。
文摘A rotary-concentrating device for thermal conduction is constructed to control and guide thermal energy transmitting in elastic plates.The designed device has the ability of concentrating for thermal conduction and controlling the processes of thermal diffusion in a plate.The multilayered isotropic material properties of the rotary-concentrating device are derived based on the transformation and rotary medium method and a rotation parameter to control the thermal diffusion process is introduced.The efficiency of the rotary-concentrating device for thermal conduction is verified.Stability of temperature fields in a plate with the rotary-concentrating device is analyzed to study the performance of rotary-concentrating.Numerical examples show that the constructed rotary-concentrating device for thermal conduction can effectively rotate and focus on the thermal energy into the device for a wide range of diffusion temperatures,which can enhance the thermal conduction.Therefore,this study can provide a theoretical support for potential applications in fields of energy harvesting and thermal conduction control.
文摘Due to the volume conduction,electroencephalogram（EEG） gives a rather blurred image of brain activities. It is a challenge for generating satisfactory performance with EEG. This paper studies the multiple areas fusion of EEG classifiers to improve the motor imagery EEG classification performance. Two feature extraction methods are employed to extract the feature from three different areas of EEG. One is power spectral density（PSD）, and the other is common spatial patterns（CSP）. Classifiers are designed based on the well-known linear discrimination analysis（LDA）. The fusion of the individual classifiers is realized by means of the Choquet fuzzy integral. It is demonstrated that the proposed method comes with better performance compared with the individual classifier.
基金the AID(Agence Innovation Défense)and the Nouvelle Aquitaine Region。
文摘CONSPECTUS:Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymerbased additive manufacturing(AM),driven by the growing demand for multifunctional 3D-printing.While several AM techniques have been adapted to process conductive composites,Digital Light Processing(DLP)stands out for its high-resolution and fast-curing capabilities.However,it poses a central limitation:the requirement for optical transparency in the printing resin,which is compromised by the incorporation of conventional conductive fillers.This Account highlights the advances in overcoming three fundamental challenges in the field:(i)How can conductive nanocomposites be printed by DLP without compromising resolution?(ii)How can high electrical conductivity be achieved at low filler content?(iii)What is the origin of anisotropic conductivity in printed objects,and how can it be mitigated?To address the first question,the authors introduced a strategy based on UV-transparent precursors,specifically monolayer graphene oxide(GO).GO’s minimal UV absorption allows its use as a printable nanofiller at weight fractions up to 0.35 vol%,preserving the curing depth and optical clarity required for DLP.Postprinting thermal reduction of GO into reduced graphene oxide(rGO)yields nanocomposites with conductivities up to 10^(-2)S m^(-1)-comparable to conventional carbon nanotube(CNT)systems but achieved without high UV attenuation.To tackle the second question,the authors explored the use of single-walled carbon nanotubes(SWCNTs),which,due to their high aspect ratio and intrinsic conductivity,exhibit ultralow percolation thresholds(<0.01 vol%).At these concentrations,UV interference is negligible.However,the need for surfactant-assisted dispersion introduces contact resistance,limiting conductivity.To overcome this,this Account presents a hybrid formulation in which GO serves as both dispersant and conductive additive,enhancing internanotube contacts upon reduction.This approach achieves conductivities up to 0.3 S m^(-1),with a total filler content below 0.15 vol%,representing a significant leap in performance without sacrificing resolution.To resolve the third question regarding electrical anisotropy,the study employs polarized Raman spectroscopy,conclusively showing that nanotube alignment is not responsible for the observed directional conductivity differences.Instead,the anisotropy arises from interfacial contact resistance between printed layers,an intrinsic artifact of the layer-by-layer DLP process.Mitigation strategies such as delayed UV curing and temperature-controlled printing were shown to significantly reduce this resistance and improve isotropy.Beyond addressing these scientific questions,this Account highlights the practical impact of these materials.Notably,hybrid nanocomposites exhibited strong potential in microwave absorption,reaching broadband reflection losses below-10 dB at low filler loadings,due to combined ohmic and dielectric losses.These outcomes demonstrate that high-resolution,fast DLP printing of conductive materials is not only feasible but also tunable and scalable for applications in sensors,soft robotics,and electromagnetic shielding.By answering these key questions,the work establishes a foundation for the rational design of printable conductive nanocomposites,balancing optical compatibility,conductivity,and mechanical precision-paving the way for next-generation functional devices fabricated through vat photopolymerization.
基金the Competency Development Program for Industry Specialists of the Korean Ministry of Trade,Industry,and Energy(MOTIE),operated by the Korea Institute for Advancement of Technology(KIAT,No.P0002397,HRD program for Industrial Convergence of Wearable Smart De-vices)the Technology Innovation Program(No.20000773,Development of nano multi sensors based on wearable patch for nonhematological monitoring of metabolic syndrome)funded by the Ministry of Trade,Industry&Energy(MI,Korea).
文摘Long-term bioelectric potential recording requires highly reliable wearable dry electrodes.Laser-induced graphene(LIG)dry electrodes on polyimide(PI)films are difficult to conform to the skin due to the non-stretchability and low flexibility of PI films.As a result,high interface impedance and motion artifacts can occur during body movements.Transferring LIG to flexible substrates such as polydimethylsiloxane(PDMS)and Ecoflex allows for stretchability and flexibility.However,the transfer process produces a significant loss of conductivity destroying the structural function and electron conduction properties of the LIG.We found robust physical and chemical bonding effects between LIG and styrene-ethylene-butylene-styrene(SEBS)thermoplastic elastomer substrates and proposed a simple and robust low-conductivity loss transfer technique.Successfully embedded LIG onto SEBS to obtain high stretchability,high flexibility,low conductivity losses.Electrophoretic deposition(EPD)of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid(PEDOT:PSS)on LIG forms an ultrathin polymer conductive coating.The deposition thickness of the conductive polymer is adjusted by controlling the EPD deposition time to achieve optimal conductivity and chemical stability.SEBS/LIG/PEDOT:PSS(SLPP)dry electrodes have high conductivity(114Ω/Sq),stretchability(300%)and reliability(30%stretch,15,000 cycles),low electrode-skin impedance(14.39 kΩ,10 Hz).The detected biopotential signal has a high signal-to-noise ratio(SNR)of 35.78 dB.Finally,the feasibility of SLPP dry electrodes for long-term biopotential monitoring and biopotential-based human-machine interface control of household appliances was verified.
基金supported by the National Natural Science Foundation of China(20673074&20973119)
文摘A stochastic model of chemical reaction-heat conduction-diffusion for a one-dimensional gaseous system under Dirichlet or zero-fluxes boundary conditions is proposed in this paper.Based on this model,we extend the theory of the broadening exponent of critical fluctuations to cover the chemical reaction-heat conduction coupling systems as an asymptotic property of the corresponding Markovian master equation(ME),and establish a valid stochastic thermodynamics for such systems.As an illustration,the non-isothermal and inhomogeneous Schl-gl model is explicitly studied.Through an order analysis of the contributions from both the drift and diffusion to the evolution of the probability distribution in the corresponding Fokker-Planck equation(FPE)in the approach to bifurcation,we have identified the critical transition rule for the broadening exponent of the fluctuations due to the coupling between chemical reaction and heat conduction.It turns out that the dissipation induced by the critical fluctuations reaches a deterministic level,leading to a thermodynamic effect on the nonequilibrium physico-chemical processes.
