This work proposes and fabricates the 4H-SiC power MOSFET with top oxide and double P-well(TODP-MOSFET)to enhance the single-event radiation tolerance of the gate oxide.Simulation results suggest that the proposed TOD...This work proposes and fabricates the 4H-SiC power MOSFET with top oxide and double P-well(TODP-MOSFET)to enhance the single-event radiation tolerance of the gate oxide.Simulation results suggest that the proposed TODP structure reduces the peak electric field within the oxide and minimizes the sensitive region by more than 70%compared to C-MOSFETs.Experimental results show that the gate degradation voltage of the TODP-MOSFET is higher than that of the C-MOSFET,and the gate leakage current is reduced by 95%compared to the C-MOSFET under heavy-ion irradiation with a linear energy transfer(LET)value exceeding 75 MeV·cm^(2)/mg.展开更多
Due to interaction among cells, it is too complex to build an exactanalytical model for the power dissipation within the cell membrane in suspensions exposed toexternal fields. An approximate equivalence method is pro...Due to interaction among cells, it is too complex to build an exactanalytical model for the power dissipation within the cell membrane in suspensions exposed toexternal fields. An approximate equivalence method is proposed to resolve this problem. Based on theeffective medium theory, the transmembrane voltage on cells in suspensions was investigated by theequivalence principle. Then the electric field in the cell membrane was determined. Finally,analytical solutions for the power dissipation within the cell membrane in suspensions exposed toexternal fields were derived according to the Joule principle. The equations show that theconductive power dissipation is predominant within the cell membrane in suspensions exposed todirect current or lower frequencies, and dielectric power dissipation prevails at high frequenciesexceeding the relaxation frequency of the exposed membrane.展开更多
Previous studies show that exposure to high-voltage electric fields would influence the electro-cardiogram both in experimental animals and human beings.The effects of the external electric fields upon action potentia...Previous studies show that exposure to high-voltage electric fields would influence the electro-cardiogram both in experimental animals and human beings.The effects of the external electric fields upon action potential of cardiac cells are studied in this paper based on the dynamical model,LR91.Fourth-order Runger-Kuta is used to analyze the change of potassium ion channels exposed to external electric fields in detail.Results indicate that external electric fields could influence the current of potassium ion by adding an induced component voltage on membrane.This phenomenon might be one of the reasons of heart rate anomaly under the high-voltage electric fields.展开更多
The regime of horizontal subcooled film boiling is characterized by the formation of a thin layer of vapor coveringthe surface of a flat horizontal heater. Based on the equations of motion of a viscous incompressible ...The regime of horizontal subcooled film boiling is characterized by the formation of a thin layer of vapor coveringthe surface of a flat horizontal heater. Based on the equations of motion of a viscous incompressible fluid and theequation of heat transfer, the stability of such a vapor film is investigated. The influence of the modulation of thegravity field caused by vertical vibrations of the heater of finite frequency, as well as a constant electric fieldapplied normal to the surface of the heater, is taken into account. It is shown that in the case of a thick vaporfilm, the phase transition has a little effect on the thresholds for the occurrence of parametric instability in thesystem and its transformation into the most dangerous one. At the same time, the electric field contributes toan increase in these thresholds. It was found that the effect of vibrations on the stabilization of non-parametricinstability in the system is possible only in a narrow region of the parameter space where long-wave damped disturbances exist and consists of reducing the critical heat flux of stabilization. A vapor film stabilized in this waycan be destroyed due to the development of parametric instability. In contrast to the case of a thick vapor layer,the threshold for the onset of parametric instability for thin films largely depends on the value of subcooling in thesystem. In addition, this threshold decreases with increasing electric field strength. For a vapor film ten micronsthick, the instability threshold can be reduced by a factor of three or more by applying an electric field of aboutthree million volts per meter.展开更多
Heterojunction construction,especially S-scheme heterojunction,represents an efficient universal strategy to achieve high-performance photocatalytic materials.For further performance stimulation of these well-designed...Heterojunction construction,especially S-scheme heterojunction,represents an efficient universal strategy to achieve high-performance photocatalytic materials.For further performance stimulation of these well-designed heterojunctions,modulating the interfacial internal electric field(IEF)to steer dynamic charge transfer represents a promising approach.Herein,we realized the precise regulation of Fermi level(E_(F))of the oxidation semiconductor(mesoporous WO_(3-x))by tailoring the concentration of oxygen vacancies(V_(O)),maximizing the IEF intensity in Cs_(2)CuBr_(4)@WO_(3-x)(CCB@WO_(3-x))S-scheme heterojunction.The augmented IEF affords a robust driving force for directional electron delivery,leading to boosted charge separation.Hence,the developed CCB@WO_(3-x)S-scheme heterojunction demonstrated outstanding photocatalytic CO_(2)reduction performance,with the electron consumption rate(Relectron)up to 390.34μmol g^(-1)h^(-1),which is 3.28 folds higher than that of pure CCB.An in-depth analysis of the S-scheme electron transfer mode was presented via theoretical investigations,electron spin resonance(ESR),photo-irradiated Kelvin probe force microscopy(KPFM),and in-situ X-ray photoelectron spectroscopy(XPS).Finally,the CO_(2)photoconversion route was explored in detail using in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and DFT theoretical calculations.展开更多
The so-called fourth-generation biodegradable vascular stent has become a research hotspot in thefield of bioengineering because of its good degradation ability and drug-loading characteristics.However,the preparation...The so-called fourth-generation biodegradable vascular stent has become a research hotspot in thefield of bioengineering because of its good degradation ability and drug-loading characteristics.However,the preparationof polymer-degraded vascular stents is affected by known problem such as poor processflexibility,low formingaccuracy,large diameter wall thickness,limited complex pore structure,weak mechanical properties of radial support and high process cost.In this study,a deposition technique based on a high-voltage electric-field-driven continuous rotating jet is proposed to fabricate fully degraded polymer vascular stents.The experimental results showthat,due to the rotation of the deposition axis,the deposition direction of PCL(polycaprolactone)micro-jet isalways tangent to the surface of the deposition axis.The direction of the viscous drag force is also consistent withthe deposition direction of the jet.It is shown that by setting different rotation speeds of deposition axisωandlinear motion speeds of the nozzle V,the direction of rotation,pitch and angle of the individual printed spiralcurve can be precisely tuned.In the process of multiple spiral curves matching the deposition forming thin walltube mesh,the mesh shape and size of the thin wall tube can be accurately controlled by changing the number ofmatching spiral curves and the size of the matching position bias distance.Finally,the characteristics of a PCLtubular stent sample(with uniform-size microfibers and mesh shape),fabricated under the appropriate processparameters are described in detail.展开更多
Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu...Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu nano-sea urchins(PdCu NSUs)featured with high-curvature nanotips,by which the interfacial microenvironment is expected to be tailored to the electrocatalytic reactions.PdCu NSUs exhibit excellent activity for ethanol electrooxidation,with a specific activity of 4.11 mA cm^(-2)and a mass activity of 2.24 mAμg_(Pd)^(-1),and a high Faraday efficiency(FE)of 96.4%toward acetic acid.COMSOL finite element simulations confirm that the unique nanotips could induce a local electric field due to the accumulation of positive charges in the nanotips,resulting in enrichment of OH^(-)at the catalyst surface to promote the formation of Pd-OH_(ads),a species required by ethanol dehydrogenation.Furthermore,DFT calculations and in-situ electrochemical Fourier transform infrared spectroscopy discover that the d-band center of Pd significantly downshifts in PdCu alloy,which facilitates the desorption of the produced acetic acid.This work provides a new electrocata lytic material with high-curvature nanotips,and also clarifies how the material morphology,by inducing local electric fields,affects the interfacial microenvironment and thus the catalytic activity and selectivity.展开更多
Nonlinear electrically conductive composites are widely used for electric field grading in HVDC systems. However, the composites prepared using current methods can rarely simultaneously meet the requirements of a high...Nonlinear electrically conductive composites are widely used for electric field grading in HVDC systems. However, the composites prepared using current methods can rarely simultaneously meet the requirements of a high nonlinear coefficient, low switching field and low filler content, which limits their application scope. In this study, by applying a 10-kHz AC electric field during preparation, the prepared tetra-needle-shaped ZnO whisker/carbon fiberlliquid silicone rubber (T-ZnOw/CFILSR) composites can be implemented in a manner to meet the above three requirements. The electric field-assisted LSR composites filled with 20 phr T-ZnOw and 5 phr CF can have a switching field as low as 420 V /mm and a nonlinear coefficient up to 11.7. The mechanism for the electric field-assisted enhancement of the nonlinear characteristics of the T-ZnOw/CFILSR ternary hybrid system is explained based on the electromechanics of the suspended particles. The nonlinear characteristics and the filler content do not present a positive correlation, and a low (< 10 phr) or high (> 30 phr) filler content leads to decreased nonlinear characteristics in the composites. Compared with LSR, the electric field-assisted composites introduce a large number of shallow traps with increased trap density and reduced trap energy levels.展开更多
基金supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U2341220)the Hefei Comprehensive National Science Center。
文摘This work proposes and fabricates the 4H-SiC power MOSFET with top oxide and double P-well(TODP-MOSFET)to enhance the single-event radiation tolerance of the gate oxide.Simulation results suggest that the proposed TODP structure reduces the peak electric field within the oxide and minimizes the sensitive region by more than 70%compared to C-MOSFETs.Experimental results show that the gate degradation voltage of the TODP-MOSFET is higher than that of the C-MOSFET,and the gate leakage current is reduced by 95%compared to the C-MOSFET under heavy-ion irradiation with a linear energy transfer(LET)value exceeding 75 MeV·cm^(2)/mg.
文摘Due to interaction among cells, it is too complex to build an exactanalytical model for the power dissipation within the cell membrane in suspensions exposed toexternal fields. An approximate equivalence method is proposed to resolve this problem. Based on theeffective medium theory, the transmembrane voltage on cells in suspensions was investigated by theequivalence principle. Then the electric field in the cell membrane was determined. Finally,analytical solutions for the power dissipation within the cell membrane in suspensions exposed toexternal fields were derived according to the Joule principle. The equations show that theconductive power dissipation is predominant within the cell membrane in suspensions exposed todirect current or lower frequencies, and dielectric power dissipation prevails at high frequenciesexceeding the relaxation frequency of the exposed membrane.
基金supported by the National Nature Science Foundation of China under Grant No. 30400105
文摘Previous studies show that exposure to high-voltage electric fields would influence the electro-cardiogram both in experimental animals and human beings.The effects of the external electric fields upon action potential of cardiac cells are studied in this paper based on the dynamical model,LR91.Fourth-order Runger-Kuta is used to analyze the change of potassium ion channels exposed to external electric fields in detail.Results indicate that external electric fields could influence the current of potassium ion by adding an induced component voltage on membrane.This phenomenon might be one of the reasons of heart rate anomaly under the high-voltage electric fields.
基金supported by the Ministry of Science and High Education of Russia(Theme No.121031700169-1).
文摘The regime of horizontal subcooled film boiling is characterized by the formation of a thin layer of vapor coveringthe surface of a flat horizontal heater. Based on the equations of motion of a viscous incompressible fluid and theequation of heat transfer, the stability of such a vapor film is investigated. The influence of the modulation of thegravity field caused by vertical vibrations of the heater of finite frequency, as well as a constant electric fieldapplied normal to the surface of the heater, is taken into account. It is shown that in the case of a thick vaporfilm, the phase transition has a little effect on the thresholds for the occurrence of parametric instability in thesystem and its transformation into the most dangerous one. At the same time, the electric field contributes toan increase in these thresholds. It was found that the effect of vibrations on the stabilization of non-parametricinstability in the system is possible only in a narrow region of the parameter space where long-wave damped disturbances exist and consists of reducing the critical heat flux of stabilization. A vapor film stabilized in this waycan be destroyed due to the development of parametric instability. In contrast to the case of a thick vapor layer,the threshold for the onset of parametric instability for thin films largely depends on the value of subcooling in thesystem. In addition, this threshold decreases with increasing electric field strength. For a vapor film ten micronsthick, the instability threshold can be reduced by a factor of three or more by applying an electric field of aboutthree million volts per meter.
基金This work was financially supported by the National Natural Science Foundation of China(51972213)Natural Science Foundation of Shanghai(22ZR1460700).
文摘Heterojunction construction,especially S-scheme heterojunction,represents an efficient universal strategy to achieve high-performance photocatalytic materials.For further performance stimulation of these well-designed heterojunctions,modulating the interfacial internal electric field(IEF)to steer dynamic charge transfer represents a promising approach.Herein,we realized the precise regulation of Fermi level(E_(F))of the oxidation semiconductor(mesoporous WO_(3-x))by tailoring the concentration of oxygen vacancies(V_(O)),maximizing the IEF intensity in Cs_(2)CuBr_(4)@WO_(3-x)(CCB@WO_(3-x))S-scheme heterojunction.The augmented IEF affords a robust driving force for directional electron delivery,leading to boosted charge separation.Hence,the developed CCB@WO_(3-x)S-scheme heterojunction demonstrated outstanding photocatalytic CO_(2)reduction performance,with the electron consumption rate(Relectron)up to 390.34μmol g^(-1)h^(-1),which is 3.28 folds higher than that of pure CCB.An in-depth analysis of the S-scheme electron transfer mode was presented via theoretical investigations,electron spin resonance(ESR),photo-irradiated Kelvin probe force microscopy(KPFM),and in-situ X-ray photoelectron spectroscopy(XPS).Finally,the CO_(2)photoconversion route was explored in detail using in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and DFT theoretical calculations.
基金supported by the National Natural Science Foundation of China(Grant Nos.51305128 and 52005059)The Key Scientific and Technological Project of Henan Province(Grant Nos.242102231054 and 242102220073)The Provincial Graduate Quality Engineering Project(Grant No.YJS2024JD38)。
文摘The so-called fourth-generation biodegradable vascular stent has become a research hotspot in thefield of bioengineering because of its good degradation ability and drug-loading characteristics.However,the preparationof polymer-degraded vascular stents is affected by known problem such as poor processflexibility,low formingaccuracy,large diameter wall thickness,limited complex pore structure,weak mechanical properties of radial support and high process cost.In this study,a deposition technique based on a high-voltage electric-field-driven continuous rotating jet is proposed to fabricate fully degraded polymer vascular stents.The experimental results showthat,due to the rotation of the deposition axis,the deposition direction of PCL(polycaprolactone)micro-jet isalways tangent to the surface of the deposition axis.The direction of the viscous drag force is also consistent withthe deposition direction of the jet.It is shown that by setting different rotation speeds of deposition axisωandlinear motion speeds of the nozzle V,the direction of rotation,pitch and angle of the individual printed spiralcurve can be precisely tuned.In the process of multiple spiral curves matching the deposition forming thin walltube mesh,the mesh shape and size of the thin wall tube can be accurately controlled by changing the number ofmatching spiral curves and the size of the matching position bias distance.Finally,the characteristics of a PCLtubular stent sample(with uniform-size microfibers and mesh shape),fabricated under the appropriate processparameters are described in detail.
基金financially supported by the Major Fundamental Research of Natural Science Foundation of Shandong Province(ZR2022ZD10)National Natural Science Foundation of China(22478211,22372017)+2 种基金Postdoctoral Fellowship Program of CPSF(GZC20231193)Liaoning Binhai Laboratory(LBLG-2024-10)Qingdao Postdoctoral Applied Research Project(QDBSH20240102068)。
文摘Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu nano-sea urchins(PdCu NSUs)featured with high-curvature nanotips,by which the interfacial microenvironment is expected to be tailored to the electrocatalytic reactions.PdCu NSUs exhibit excellent activity for ethanol electrooxidation,with a specific activity of 4.11 mA cm^(-2)and a mass activity of 2.24 mAμg_(Pd)^(-1),and a high Faraday efficiency(FE)of 96.4%toward acetic acid.COMSOL finite element simulations confirm that the unique nanotips could induce a local electric field due to the accumulation of positive charges in the nanotips,resulting in enrichment of OH^(-)at the catalyst surface to promote the formation of Pd-OH_(ads),a species required by ethanol dehydrogenation.Furthermore,DFT calculations and in-situ electrochemical Fourier transform infrared spectroscopy discover that the d-band center of Pd significantly downshifts in PdCu alloy,which facilitates the desorption of the produced acetic acid.This work provides a new electrocata lytic material with high-curvature nanotips,and also clarifies how the material morphology,by inducing local electric fields,affects the interfacial microenvironment and thus the catalytic activity and selectivity.
基金supported by the National Natural Science Foundation of China(51477085,51477086)the Shenzhen Fundamental Research and Discipline Layout Project(JCYJ20180508152044145)。
文摘Nonlinear electrically conductive composites are widely used for electric field grading in HVDC systems. However, the composites prepared using current methods can rarely simultaneously meet the requirements of a high nonlinear coefficient, low switching field and low filler content, which limits their application scope. In this study, by applying a 10-kHz AC electric field during preparation, the prepared tetra-needle-shaped ZnO whisker/carbon fiberlliquid silicone rubber (T-ZnOw/CFILSR) composites can be implemented in a manner to meet the above three requirements. The electric field-assisted LSR composites filled with 20 phr T-ZnOw and 5 phr CF can have a switching field as low as 420 V /mm and a nonlinear coefficient up to 11.7. The mechanism for the electric field-assisted enhancement of the nonlinear characteristics of the T-ZnOw/CFILSR ternary hybrid system is explained based on the electromechanics of the suspended particles. The nonlinear characteristics and the filler content do not present a positive correlation, and a low (< 10 phr) or high (> 30 phr) filler content leads to decreased nonlinear characteristics in the composites. Compared with LSR, the electric field-assisted composites introduce a large number of shallow traps with increased trap density and reduced trap energy levels.
