Herein,a physical and mathematical model of the voltage−current characteristics of a p−n heterostructure with quantum wells(QWs)is prepared using the Sah−Noyce−Shockley(SNS)recombination mechanism to show the SNS reco...Herein,a physical and mathematical model of the voltage−current characteristics of a p−n heterostructure with quantum wells(QWs)is prepared using the Sah−Noyce−Shockley(SNS)recombination mechanism to show the SNS recombination rate of the correction function of the distribution of QWs in the space charge region of diode configuration.A comparison of the model voltage−current characteristics(VCCs)with the experimental ones reveals their adequacy.The technological parameters of the structure of the VCC model are determined experimentally using a nondestructive capacitive approach for determining the impurity distribution profile in the active region of the diode structure with a profile depth resolution of up to 10Å.The correction function in the expression of the recombination rate shows the possibility of determining the derivative of the VCCs of structures with QWs with a nonideality factor of up to 4.展开更多
Cathode materials that possess high output voltage,as well as those that can be mass-produced using facile techniques,are crucial for the advancement of aqueous zinc-ion battery(ZIBs)applications,Herein,we present for...Cathode materials that possess high output voltage,as well as those that can be mass-produced using facile techniques,are crucial for the advancement of aqueous zinc-ion battery(ZIBs)applications,Herein,we present for the first time a new porous K_(0.5)VOPO_(4)·1.5H_(2)O polyanionic cathode(P-KIVP)with high output voltage(above 1.2 V)that can be manufactured at room temperature using straightforward coprecipitation and etching techniques.The P-KVP cathode experiences anisotropic crystal plane expansion via a sequential solid-solution intercalation and phase co nversion pathway throughout the Zn^(2+)storage process,as confirmed by in-situ synchrotron X-ray diffraction and ex-situ X-ray photoelectron spectroscopy.Similar to other layered vanadium-based polyanionic materials,the P-KVP cathode experiences a progressive decline in voltage during the cycle,which is demonstrated to be caused by the irreversible conversion into amorphous VO_(x).By introducing a new electrolyte containing Zn(OTF)_(2) to a mixed triethyl phosphate and water solution,it is possible to impede this irreversible conversion and obtain a high output voltage and longer cycle life by forming a P-rich cathode electrolyte interface layer.As a proof-of-concept,the flexible fiber-shaped ZIBs based on modified electrolyte woven into a fabric watch band can power an electronic watch,highlighting the application potential of P-KVP cathode.展开更多
PEO-based all-solid-state electrolytes are extensively utilized and researched owing to their exceptional safety,low-mass-density,and cost-effectiveness.However,the low oxidation potential of PEO makes the interface p...PEO-based all-solid-state electrolytes are extensively utilized and researched owing to their exceptional safety,low-mass-density,and cost-effectiveness.However,the low oxidation potential of PEO makes the interface problem with the high-voltage cathode extremely severe.In this work,the impedance of PEO-based all-solid-state batteries with high-voltage cathode(NCM811)was studied at different potentials.The Nyquist plots displayed a gyrate arc at low-frequencies for NCM811/PEO interface.Based on the kinetic modeling,it was deduced that there is a decomposition reaction of PEO-matrix in addition to de-embedded reaction of NCM811,and the PEO intermediate product(dehydra-PEO)adsorbed on the electrode surface leading to low-frequency inductive arcs.Furthermore,the distribution of relaxation time shows the dehydra-PEO results in the kinetic tardiness of the charge transfer process in the temporal dimension.Hence,an artificial interface layer(CEI_(x))was modified on the surface of NCM811 to regulate the potential of cathode/electrolyte interface to prevent the high-voltage deterioration of PEO.NCM/CEI_(x)/PEO batteries exhibit capacity retentions of 96.0%,84.6%,and 76.8%after undergoing 100 cycles at cut-off voltages of 4.1,4.2,and 4.3 V,respectively.Therefore,here the failure mechanism of high-voltage PEO electrolyte is investigated by EIS and a proposed solving strategy is presented.展开更多
Sodium-ion batteries hold great promise as next-generation energy storage systems.However,the high instability of the electrode/electrolyte interphase during cycling has seriously hindered the development of SIBs.In p...Sodium-ion batteries hold great promise as next-generation energy storage systems.However,the high instability of the electrode/electrolyte interphase during cycling has seriously hindered the development of SIBs.In particular,an unstable cathode–electrolyte interphase(CEI)leads to successive electrolyte side reactions,transition metal leaching and rapid capacity decay,which tends to be exacerbated under high-voltage conditions.Therefore,constructing dense and stable CEIs are crucial for high-performance SIBs.This work reports localized high-concentration electrolyte by incorporating a highly oxidation-resistant sulfolane solvent with non-solvent diluent 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether,which exhibited excellent oxidative stability and was able to form thin,dense and homogeneous CEI.The excellent CEI enabled the O3-type layered oxide cathode NaNi_(1/3)Mn_(1/3)Fe_(1/3)O_(2)(NaNMF)to achieve stable cycling,with a capacity retention of 79.48%after 300 cycles at 1 C and 81.15%after 400 cycles at 2 C with a high charging voltage of 4.2 V.In addition,its nonflammable nature enhances the safety of SIBs.This work provides a viable pathway for the application of sulfolane-based electrolytes on SIBs and the design of next-generation high-voltage electrolytes.展开更多
Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid compositi...Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid composition,abundance of mechanosensors,and cytoskeletal dynamics make cells more or less likely to sense these forces.Intrinsic and extrinsic cues are integrated by cells and this combined information determines the rate and dynamics of membrane protrusion growth or retraction(Yamada and Sixt,2019).Cell protrusions are extensions of the plasma membrane that play crucial roles in diverse contexts such as cell migration and neuronal synapse formation.In the nervous system,neurons are highly dynamic cells that can change the size and number of their pre-and postsynaptic elements(called synaptic boutons and dendritic spines,respectively),in response to changes in the levels of synaptic activity through a process called plasticity.Synaptic plasticity is a hallmark of the nervous system and is present throughout our lives,being required for functions like memory formation or the learning of new motor skills(Minegishi et al.,2023;Pillai and Franze,2024).展开更多
The complex morphological,anatomical,physiological,and chemical mechanisms within the aging brain have been the hot topic of research for centuries.The aging process alters the brain structure that affects functions a...The complex morphological,anatomical,physiological,and chemical mechanisms within the aging brain have been the hot topic of research for centuries.The aging process alters the brain structure that affects functions and cognitions,but the worsening of such processes contributes to the pathogenesis of neurodegenerative disorders,such as Alzheimer's disease.Beyond these observable,mild morphological shifts,significant functional modifications in neurotransmission and neuronal activity critically influence the aging brain.Understanding these changes is important for maintaining cognitive health,especially given the increasing prevalence of age-related conditions that affect cognition.This review aims to explore the age-induced changes in brain plasticity and molecular processes,differentiating normal aging from the pathogenesis of Alzheimer's disease,thereby providing insights into predicting the risk of dementia,particularly Alzheimer's disease.展开更多
Regulated cell death is a form of cell death that is actively controlled by biomolecules.Several studies have shown that regulated cell death plays a key role after spinal cord injury.Pyroptosis and ferroptosis are ne...Regulated cell death is a form of cell death that is actively controlled by biomolecules.Several studies have shown that regulated cell death plays a key role after spinal cord injury.Pyroptosis and ferroptosis are newly discovered types of regulated cell deaths that have been shown to exacerbate inflammation and lead to cell death in damaged spinal cords.Autophagy,a complex form of cell death that is interconnected with various regulated cell death mechanisms,has garnered significant attention in the study of spinal cord injury.This injury triggers not only cell death but also cellular survival responses.Multiple signaling pathways play pivotal roles in influencing the processes of both deterioration and repair in spinal cord injury by regulating pyroptosis,ferroptosis,and autophagy.Therefore,this review aims to comprehensively examine the mechanisms underlying regulated cell deaths,the signaling pathways that modulate these mechanisms,and the potential therapeutic targets for spinal cord injury.Our analysis suggests that targeting the common regulatory signaling pathways of different regulated cell deaths could be a promising strategy to promote cell survival and enhance the repair of spinal cord injury.Moreover,a holistic approach that incorporates multiple regulated cell deaths and their regulatory pathways presents a promising multi-target therapeutic strategy for the management of spinal cord injury.展开更多
In this paper, we demonstrate that a Schottky drain can improve the forward and reverse blocking voltages (BVs) simultaneously in A1GaN/GaN high-electron mobility transistors (HEMTs). The mechanism of improving th...In this paper, we demonstrate that a Schottky drain can improve the forward and reverse blocking voltages (BVs) simultaneously in A1GaN/GaN high-electron mobility transistors (HEMTs). The mechanism of improving the two BVs is investigated by analysing the leakage current components and by software simulation. The forward BV increases from 72 V to 149 V due to the good Schottky contact morphology. During the reverse bias, the buffer leakage in the Ohmic- drain HEMT increases significantly with the increase of the negative drain bias. For the Schottky-drain HEMT, the buffer leakage is suppressed effectively by the formation of the depletion region at the drain terminal. As a result, the reverse BV is enhanced from -5 V to -49 V by using a Schottky drain. Experiments and the simulation indicate that a Schottky drain is desirable for power electronic applications.展开更多
LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)layered oxides have been regarded as promising alternative cathodes for the next generation of high-energy lithium ion batteries(LIBs)due to high discharge capacities and energy ...LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)layered oxides have been regarded as promising alternative cathodes for the next generation of high-energy lithium ion batteries(LIBs)due to high discharge capacities and energy densities at high operation voltage.However,the capacity fading under high operation voltage still restricts the practical application.Herein,the capacity degradation mechanism of NCM811 at atomic-scale is studied in detail under various cut-off voltages using aberration-corrected scanning transmission electron microscopy(STEM).It is observed that the crystal structure of NCM811 evolution from a layered structure to a rock-salt phase is directly accompanied by serious intergranular cracks under 4.9 V,which is distinguished from the generally accepted structure evolution of layered,disordered layered,defect rock salt and rock salt phases,also observed under 4.3 and 4.7 V.The electron energy loss spectroscopy analysis also confirms the reduction of Ni and Co from the surface to the bulk,not the previously reported only Li/Ni interlayer mixing.The degradation mechanism of NCM811 at a high cut-off voltage of4.9 V is attributed to the formation of intergranular cracks induced by defects,the direct formation of the rock salt phase,and the accompanied reduction of Ni^(2+)and Co^(2+)phases from the surface to the bulk.展开更多
P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this m...P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.展开更多
This paper discusses the breakdown mechanism and proposes a new simulation and test method of breakdown voltage (BV) for an ultra-high-voltage (UHV) high-side thin layer silicon-on-insulator (SOI) p-channel low-...This paper discusses the breakdown mechanism and proposes a new simulation and test method of breakdown voltage (BV) for an ultra-high-voltage (UHV) high-side thin layer silicon-on-insulator (SOI) p-channel low-density metal- oxide semiconductor (LDMOS). Compared with the conventional simulation method, the new one is more accordant with the actual conditions of a device that can be used in the high voltage circuit. The BV of the SOI p-channel LDMOS can be properly represented and the effect of reduced bulk field can be revealed by employing the new simulation method. Simulation results show that the off-state (on-state) BV of the SOI p-channel LDMOS can reach 741 (620) V in the 3μm-thick buried oxide layer, 50μm-length drift region, and at -400 V back-gate voltage, enabling the device to be used in a 400 V UHV integrated circuit.展开更多
Load characteristics are the main factor to affect voltage stability. In addition, load modeling reflecting the actual load characteristics has been a well—known difficult problem and unsolved so far, It is mainly du...Load characteristics are the main factor to affect voltage stability. In addition, load modeling reflecting the actual load characteristics has been a well—known difficult problem and unsolved so far, It is mainly due to the fact that the load composition, amount and characteristics are always changing. This paper introduces the slip into the equivalent impedance load model to analyze load characteristic, the varying slip is employed to indicate?time-varying load characteristic precisely, and considering the dissimilar load behaviors, discusses node voltage, power during the changes of load characteristic, obtains voltage inflexion and power inflexion, and then analyzes the mechanism of power system voltage instability based on static voltage stability region. An example indicates the feasibility of the method.展开更多
We investigate the instability of threshold voltage in D-mode MIS-HEMT with in-situ SiN as gate dielectric under different negative gate stresses.The complex non-monotonic evolution of threshold voltage under the nega...We investigate the instability of threshold voltage in D-mode MIS-HEMT with in-situ SiN as gate dielectric under different negative gate stresses.The complex non-monotonic evolution of threshold voltage under the negative stress and during the recovery process is induced by the combination effect of two mechanisms.The effect of trapping behavior of interface state at SiN/AlGaN interface and the effect of zener traps in AlGaN barrier layer on the threshold voltage instability are opposite to each other.The threshold voltage shifts negatively under the negative stress due to the detrapping of the electrons at SiN/AlGaN interface,and shifts positively due to zener trapping in AlGaN barrier layer.As the stress is removed,the threshold voltage shifts positively for the retrapping of interface states and negatively for the thermal detrapping in AlGaN.However,it is the trapping behavior in the AlGaN rather than the interface state that results in the change of transconductance in the D-mode MIS-HEMT.展开更多
Analyzes the mechanism of overvoltage when contactless tap changer switch which is applied in distributing transformer converted directly.When the device convert the tap off,it employs the way that the SSR is switche...Analyzes the mechanism of overvoltage when contactless tap changer switch which is applied in distributing transformer converted directly.When the device convert the tap off,it employs the way that the SSR is switched on when voltage through zero and switched off when current through zero.But in the experiment we found that overvoltage will occur in the process of changing tap changer.The paper illustrates the mechanism of overvoltage in theory by analyzing the equivalent circuit and using analytic method of transition process.展开更多
Partial discharge (PD) under a sequence of high-repetition-rate square pulses is one of the key factors leading to premature failure of insulation systems of inverter-fed motors. Polyimide (PI) film is an important ty...Partial discharge (PD) under a sequence of high-repetition-rate square pulses is one of the key factors leading to premature failure of insulation systems of inverter-fed motors. Polyimide (PI) film is an important type of insulating material used in the inverter-fed motors. In this paper, micro-morphology and structure change of PI film aged by bipolar continuous square impulse voltage (BCSIV) with ampli- tude above partial discharge inception voltage (PDIV) are investigated by scanning electron microscope (SEM). The chemical bonds of PI chain are analyzed through Fourier transform infrared spectroscopy (FTIR). The results show that the degradation mechanism of PI film is the fracturing of chemical bonds caused by the erosion from PDs. Three layers are displayed in both 100 HN film and 100 CR film. The de- gradation path of PI film is initiated from surface and then gradually extends to the interior with continuous aging. Nano-fillers can retard the degradation of PI film and prolong its lifetime.展开更多
In order to investigate the characteristics and mechanisms of subthreshold voltage hysteresis(ΔV_(th,sub)) of 4 H-SiC metal-oxide-semiconductor field-effect transistors(MOSFETs),4 H-SiC planar and trench MOSFETs and ...In order to investigate the characteristics and mechanisms of subthreshold voltage hysteresis(ΔV_(th,sub)) of 4 H-SiC metal-oxide-semiconductor field-effect transistors(MOSFETs),4 H-SiC planar and trench MOSFETs and corresponding P-type planar and trench metal-oxide-semiconductor(MOS) capacitors are fabricated and characterized.Compared with planar MOSFEF,the trench MOSFET shows hardly larger ΔV_(th,sub) in wide temperature range from 25 0 C to 300 0 C.When operating temperature range is from 25 ℃ to 300 ℃,the off-state negative V_(gs) of planar and trench MOSFETs should be safely above-4 V and-2 V,respectively,to alleviate the effect of ΔV_(th,sub) on the normal operation.With the help of P-type planar and trench MOS capacitors,it is confirmed that the obvious ΔV_(th,sub) of 4 H-SiC MOSFET originates from the high density of the hole interface traps between intrinsic Fermi energy level(E_(i)) and valence band(E_(v)).The maximumΔV_(th,sub) of trench MOSFET is about twelve times larger than that of planar MOSFET,owing to higher density of interface states(D_(it)) between E_(i) and E_(v).These research results will be very helpful for the application of 4 H-SiC MOSFET and the improvement of ΔV_(th,sub) of 4 H-SiC MOSFET,especially in 4 H-SiC trench MOSFET.展开更多
Layered cathode materials have been successfully commercialized and applied to electric vehicles.To further improve improve the energy density of these marterials is still the main efforts in the market.Therefore,deve...Layered cathode materials have been successfully commercialized and applied to electric vehicles.To further improve improve the energy density of these marterials is still the main efforts in the market.Therefore,developing high-voltage LiNi_(x)Co_(y)Mn_(z)O_(2)(x+y+z=1,NCM)to achieve high energy density is particularly important.However,under high voltage cycling,NCM often exhibits rapid capacity degradation,which can be attributed to oxygen release,structural phase transition and particle cracking.In this work,the representative single-crystal LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM523)was studied under various high charge cut-off voltages.Analysis by x-ray diffraction(XRD),transmission electron microscope(TEM)and electron back scatter diffraction(EBSD)measurements indicated that the rock-salt phase is formed on the surface of the particles after high voltage cycling,which is responsible for the increase of impedance and the rapid decay of capacity.Therefore,inhibiting the formation of rock-salt phase is believed an effective strategy to address the failure of NCM under high voltages.These findings provide effective guidance for the development of high-voltage NCM.展开更多
The current-voltage (I-V) curves, such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV), were employed to evaluate the effect of electrolyte concentration on the electrochemical reaction trend. From the I...The current-voltage (I-V) curves, such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV), were employed to evaluate the effect of electrolyte concentration on the electrochemical reaction trend. From the I-V curve, the electrochemical states of active, passive, transient and trans-passive region could be characterized. And then, the mechanism of the process of voltage-induced material removal in electrochemical mechanical polishing (ECMP) of copper was investigated. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were used to observe the surface profile. Finally, the oxidation and reduction processes of the Cu surface were monitored by the repetition of anodic and cathodic potential from cyclic voltammetry (CV) method in acid-and alkali-based electrolyte.展开更多
In order to investigate nanomechanical properties of nanostructured Ti metallic material, pure Ti films were prepared by magnetron sputtering at the bias voltage of 0-140 V. The microstructure of Ti films was characte...In order to investigate nanomechanical properties of nanostructured Ti metallic material, pure Ti films were prepared by magnetron sputtering at the bias voltage of 0-140 V. The microstructure of Ti films was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and high-resolution transmission electron microscopy(HRTEM). It is interesting to find that the microstructure of pure Ti films was characterized by the composite structure of amorphous-like matrix embodied with nanocrystallines, and the crystallization was improved with the increase of bias voltage. The hardness of Ti films measured by nanoindentation tests shows a linear relationship with grain sizes in the scale of 6-15 nm. However, the pure Ti films exhibit a soft tendency characterized by a smaller slope of Hall-Petch relationship. In addition, the effect of bias voltage on the growth orientation of Ti films was discussed.展开更多
基金conducted within the state assignment of the Ministry of Science and Higher Education for universities(Project No.FZRR-2023-0009).
文摘Herein,a physical and mathematical model of the voltage−current characteristics of a p−n heterostructure with quantum wells(QWs)is prepared using the Sah−Noyce−Shockley(SNS)recombination mechanism to show the SNS recombination rate of the correction function of the distribution of QWs in the space charge region of diode configuration.A comparison of the model voltage−current characteristics(VCCs)with the experimental ones reveals their adequacy.The technological parameters of the structure of the VCC model are determined experimentally using a nondestructive capacitive approach for determining the impurity distribution profile in the active region of the diode structure with a profile depth resolution of up to 10Å.The correction function in the expression of the recombination rate shows the possibility of determining the derivative of the VCCs of structures with QWs with a nonideality factor of up to 4.
基金financially supported by National Natural Science Foundation of China(No.52102270)the Natural Science Foundation of Shandong Province of China(ZR2021QE002)+1 种基金the support from the Institute startup grant from Qingdao Universitythe Shandong Center for Engineered Nonwovens(SCEN)。
文摘Cathode materials that possess high output voltage,as well as those that can be mass-produced using facile techniques,are crucial for the advancement of aqueous zinc-ion battery(ZIBs)applications,Herein,we present for the first time a new porous K_(0.5)VOPO_(4)·1.5H_(2)O polyanionic cathode(P-KIVP)with high output voltage(above 1.2 V)that can be manufactured at room temperature using straightforward coprecipitation and etching techniques.The P-KVP cathode experiences anisotropic crystal plane expansion via a sequential solid-solution intercalation and phase co nversion pathway throughout the Zn^(2+)storage process,as confirmed by in-situ synchrotron X-ray diffraction and ex-situ X-ray photoelectron spectroscopy.Similar to other layered vanadium-based polyanionic materials,the P-KVP cathode experiences a progressive decline in voltage during the cycle,which is demonstrated to be caused by the irreversible conversion into amorphous VO_(x).By introducing a new electrolyte containing Zn(OTF)_(2) to a mixed triethyl phosphate and water solution,it is possible to impede this irreversible conversion and obtain a high output voltage and longer cycle life by forming a P-rich cathode electrolyte interface layer.As a proof-of-concept,the flexible fiber-shaped ZIBs based on modified electrolyte woven into a fabric watch band can power an electronic watch,highlighting the application potential of P-KVP cathode.
基金financially supported by the National Natural Science Foundation of China (Nos. 51972023, 11210304)
文摘PEO-based all-solid-state electrolytes are extensively utilized and researched owing to their exceptional safety,low-mass-density,and cost-effectiveness.However,the low oxidation potential of PEO makes the interface problem with the high-voltage cathode extremely severe.In this work,the impedance of PEO-based all-solid-state batteries with high-voltage cathode(NCM811)was studied at different potentials.The Nyquist plots displayed a gyrate arc at low-frequencies for NCM811/PEO interface.Based on the kinetic modeling,it was deduced that there is a decomposition reaction of PEO-matrix in addition to de-embedded reaction of NCM811,and the PEO intermediate product(dehydra-PEO)adsorbed on the electrode surface leading to low-frequency inductive arcs.Furthermore,the distribution of relaxation time shows the dehydra-PEO results in the kinetic tardiness of the charge transfer process in the temporal dimension.Hence,an artificial interface layer(CEI_(x))was modified on the surface of NCM811 to regulate the potential of cathode/electrolyte interface to prevent the high-voltage deterioration of PEO.NCM/CEI_(x)/PEO batteries exhibit capacity retentions of 96.0%,84.6%,and 76.8%after undergoing 100 cycles at cut-off voltages of 4.1,4.2,and 4.3 V,respectively.Therefore,here the failure mechanism of high-voltage PEO electrolyte is investigated by EIS and a proposed solving strategy is presented.
基金financial support by National Natural Science Foundation(NNSF)of China(Nos.52202269,52002248,U23B2069,22309162)Shenzhen Science and Technology program(No.20220810155330003)+1 种基金Shenzhen Basic Research Project(No.JCYJ20190808163005631)Xiangjiang Lab(22XJ01007).
文摘Sodium-ion batteries hold great promise as next-generation energy storage systems.However,the high instability of the electrode/electrolyte interphase during cycling has seriously hindered the development of SIBs.In particular,an unstable cathode–electrolyte interphase(CEI)leads to successive electrolyte side reactions,transition metal leaching and rapid capacity decay,which tends to be exacerbated under high-voltage conditions.Therefore,constructing dense and stable CEIs are crucial for high-performance SIBs.This work reports localized high-concentration electrolyte by incorporating a highly oxidation-resistant sulfolane solvent with non-solvent diluent 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether,which exhibited excellent oxidative stability and was able to form thin,dense and homogeneous CEI.The excellent CEI enabled the O3-type layered oxide cathode NaNi_(1/3)Mn_(1/3)Fe_(1/3)O_(2)(NaNMF)to achieve stable cycling,with a capacity retention of 79.48%after 300 cycles at 1 C and 81.15%after 400 cycles at 2 C with a high charging voltage of 4.2 V.In addition,its nonflammable nature enhances the safety of SIBs.This work provides a viable pathway for the application of sulfolane-based electrolytes on SIBs and the design of next-generation high-voltage electrolytes.
基金supported by PTDC-01778/2022-NeuroDev3D,iNOVA4Health(UIDB/04462/2020 and UIDP/04462/2020)LS4FUTURE(LA/P/0087/2020)。
文摘Cells,tissues,and organs are constantly subjected to the action of mechanical forces from the extracellular environment-and the nervous system is no exception.Cell-intrinsic properties such as membrane lipid composition,abundance of mechanosensors,and cytoskeletal dynamics make cells more or less likely to sense these forces.Intrinsic and extrinsic cues are integrated by cells and this combined information determines the rate and dynamics of membrane protrusion growth or retraction(Yamada and Sixt,2019).Cell protrusions are extensions of the plasma membrane that play crucial roles in diverse contexts such as cell migration and neuronal synapse formation.In the nervous system,neurons are highly dynamic cells that can change the size and number of their pre-and postsynaptic elements(called synaptic boutons and dendritic spines,respectively),in response to changes in the levels of synaptic activity through a process called plasticity.Synaptic plasticity is a hallmark of the nervous system and is present throughout our lives,being required for functions like memory formation or the learning of new motor skills(Minegishi et al.,2023;Pillai and Franze,2024).
文摘The complex morphological,anatomical,physiological,and chemical mechanisms within the aging brain have been the hot topic of research for centuries.The aging process alters the brain structure that affects functions and cognitions,but the worsening of such processes contributes to the pathogenesis of neurodegenerative disorders,such as Alzheimer's disease.Beyond these observable,mild morphological shifts,significant functional modifications in neurotransmission and neuronal activity critically influence the aging brain.Understanding these changes is important for maintaining cognitive health,especially given the increasing prevalence of age-related conditions that affect cognition.This review aims to explore the age-induced changes in brain plasticity and molecular processes,differentiating normal aging from the pathogenesis of Alzheimer's disease,thereby providing insights into predicting the risk of dementia,particularly Alzheimer's disease.
基金supported by the Natural Science Foundation of Fujian Province,No.2021J02035(to WX).
文摘Regulated cell death is a form of cell death that is actively controlled by biomolecules.Several studies have shown that regulated cell death plays a key role after spinal cord injury.Pyroptosis and ferroptosis are newly discovered types of regulated cell deaths that have been shown to exacerbate inflammation and lead to cell death in damaged spinal cords.Autophagy,a complex form of cell death that is interconnected with various regulated cell death mechanisms,has garnered significant attention in the study of spinal cord injury.This injury triggers not only cell death but also cellular survival responses.Multiple signaling pathways play pivotal roles in influencing the processes of both deterioration and repair in spinal cord injury by regulating pyroptosis,ferroptosis,and autophagy.Therefore,this review aims to comprehensively examine the mechanisms underlying regulated cell deaths,the signaling pathways that modulate these mechanisms,and the potential therapeutic targets for spinal cord injury.Our analysis suggests that targeting the common regulatory signaling pathways of different regulated cell deaths could be a promising strategy to promote cell survival and enhance the repair of spinal cord injury.Moreover,a holistic approach that incorporates multiple regulated cell deaths and their regulatory pathways presents a promising multi-target therapeutic strategy for the management of spinal cord injury.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61334002 and 61106106)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory,China(Grant No.ZHD201206)
文摘In this paper, we demonstrate that a Schottky drain can improve the forward and reverse blocking voltages (BVs) simultaneously in A1GaN/GaN high-electron mobility transistors (HEMTs). The mechanism of improving the two BVs is investigated by analysing the leakage current components and by software simulation. The forward BV increases from 72 V to 149 V due to the good Schottky contact morphology. During the reverse bias, the buffer leakage in the Ohmic- drain HEMT increases significantly with the increase of the negative drain bias. For the Schottky-drain HEMT, the buffer leakage is suppressed effectively by the formation of the depletion region at the drain terminal. As a result, the reverse BV is enhanced from -5 V to -49 V by using a Schottky drain. Experiments and the simulation indicate that a Schottky drain is desirable for power electronic applications.
基金supported by the National Natural Science Foundation of China(U2032131)the Key R&D Program of Shaanxi Province(2021GY-118)the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SX-TD012 and 2021SXTD012)。
文摘LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)layered oxides have been regarded as promising alternative cathodes for the next generation of high-energy lithium ion batteries(LIBs)due to high discharge capacities and energy densities at high operation voltage.However,the capacity fading under high operation voltage still restricts the practical application.Herein,the capacity degradation mechanism of NCM811 at atomic-scale is studied in detail under various cut-off voltages using aberration-corrected scanning transmission electron microscopy(STEM).It is observed that the crystal structure of NCM811 evolution from a layered structure to a rock-salt phase is directly accompanied by serious intergranular cracks under 4.9 V,which is distinguished from the generally accepted structure evolution of layered,disordered layered,defect rock salt and rock salt phases,also observed under 4.3 and 4.7 V.The electron energy loss spectroscopy analysis also confirms the reduction of Ni and Co from the surface to the bulk,not the previously reported only Li/Ni interlayer mixing.The degradation mechanism of NCM811 at a high cut-off voltage of4.9 V is attributed to the formation of intergranular cracks induced by defects,the direct formation of the rock salt phase,and the accompanied reduction of Ni^(2+)and Co^(2+)phases from the surface to the bulk.
基金financial support from the National Natural Science Foundation of China (21938005, 21573147, 22005190, 22008154, 21872163)the Science & Technology Commission of Shanghai Municipality, the Natural Science Foundation of Shanghai (19DZ1205500, 19ZR1424600, 19ZR1475100)the Sichuan Science and Technology Program (2021JDRC0015 to L.S.L)。
文摘P2-type sodium layered oxide cathode (Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2)P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase transion, surface structural change, and irreversible lattice oxygen release. Here we systematically investigated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hindered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60906038)
文摘This paper discusses the breakdown mechanism and proposes a new simulation and test method of breakdown voltage (BV) for an ultra-high-voltage (UHV) high-side thin layer silicon-on-insulator (SOI) p-channel low-density metal- oxide semiconductor (LDMOS). Compared with the conventional simulation method, the new one is more accordant with the actual conditions of a device that can be used in the high voltage circuit. The BV of the SOI p-channel LDMOS can be properly represented and the effect of reduced bulk field can be revealed by employing the new simulation method. Simulation results show that the off-state (on-state) BV of the SOI p-channel LDMOS can reach 741 (620) V in the 3μm-thick buried oxide layer, 50μm-length drift region, and at -400 V back-gate voltage, enabling the device to be used in a 400 V UHV integrated circuit.
文摘Load characteristics are the main factor to affect voltage stability. In addition, load modeling reflecting the actual load characteristics has been a well—known difficult problem and unsolved so far, It is mainly due to the fact that the load composition, amount and characteristics are always changing. This paper introduces the slip into the equivalent impedance load model to analyze load characteristic, the varying slip is employed to indicate?time-varying load characteristic precisely, and considering the dissimilar load behaviors, discusses node voltage, power during the changes of load characteristic, obtains voltage inflexion and power inflexion, and then analyzes the mechanism of power system voltage instability based on static voltage stability region. An example indicates the feasibility of the method.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFB1802100)the Science Challenge Project,China(Grant No.TZ2018004)the National Natural Science Foundation of China(Grant Nos.61534007 and 11690042)。
文摘We investigate the instability of threshold voltage in D-mode MIS-HEMT with in-situ SiN as gate dielectric under different negative gate stresses.The complex non-monotonic evolution of threshold voltage under the negative stress and during the recovery process is induced by the combination effect of two mechanisms.The effect of trapping behavior of interface state at SiN/AlGaN interface and the effect of zener traps in AlGaN barrier layer on the threshold voltage instability are opposite to each other.The threshold voltage shifts negatively under the negative stress due to the detrapping of the electrons at SiN/AlGaN interface,and shifts positively due to zener trapping in AlGaN barrier layer.As the stress is removed,the threshold voltage shifts positively for the retrapping of interface states and negatively for the thermal detrapping in AlGaN.However,it is the trapping behavior in the AlGaN rather than the interface state that results in the change of transconductance in the D-mode MIS-HEMT.
基金Harbin science an technology officecontract num ber is 0 0 112 110 98
文摘Analyzes the mechanism of overvoltage when contactless tap changer switch which is applied in distributing transformer converted directly.When the device convert the tap off,it employs the way that the SSR is switched on when voltage through zero and switched off when current through zero.But in the experiment we found that overvoltage will occur in the process of changing tap changer.The paper illustrates the mechanism of overvoltage in theory by analyzing the equivalent circuit and using analytic method of transition process.
基金Project supported by National Natural Science Foundation of China (51177136).
文摘Partial discharge (PD) under a sequence of high-repetition-rate square pulses is one of the key factors leading to premature failure of insulation systems of inverter-fed motors. Polyimide (PI) film is an important type of insulating material used in the inverter-fed motors. In this paper, micro-morphology and structure change of PI film aged by bipolar continuous square impulse voltage (BCSIV) with ampli- tude above partial discharge inception voltage (PDIV) are investigated by scanning electron microscope (SEM). The chemical bonds of PI chain are analyzed through Fourier transform infrared spectroscopy (FTIR). The results show that the degradation mechanism of PI film is the fracturing of chemical bonds caused by the erosion from PDs. Three layers are displayed in both 100 HN film and 100 CR film. The de- gradation path of PI film is initiated from surface and then gradually extends to the interior with continuous aging. Nano-fillers can retard the degradation of PI film and prolong its lifetime.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFB0903203)the National Natural Science Foundation of China(Grant No.62004033)China Postdoctoral Science Foundation(Grant No.2020M683287)。
文摘In order to investigate the characteristics and mechanisms of subthreshold voltage hysteresis(ΔV_(th,sub)) of 4 H-SiC metal-oxide-semiconductor field-effect transistors(MOSFETs),4 H-SiC planar and trench MOSFETs and corresponding P-type planar and trench metal-oxide-semiconductor(MOS) capacitors are fabricated and characterized.Compared with planar MOSFEF,the trench MOSFET shows hardly larger ΔV_(th,sub) in wide temperature range from 25 0 C to 300 0 C.When operating temperature range is from 25 ℃ to 300 ℃,the off-state negative V_(gs) of planar and trench MOSFETs should be safely above-4 V and-2 V,respectively,to alleviate the effect of ΔV_(th,sub) on the normal operation.With the help of P-type planar and trench MOS capacitors,it is confirmed that the obvious ΔV_(th,sub) of 4 H-SiC MOSFET originates from the high density of the hole interface traps between intrinsic Fermi energy level(E_(i)) and valence band(E_(v)).The maximumΔV_(th,sub) of trench MOSFET is about twelve times larger than that of planar MOSFET,owing to higher density of interface states(D_(it)) between E_(i) and E_(v).These research results will be very helpful for the application of 4 H-SiC MOSFET and the improvement of ΔV_(th,sub) of 4 H-SiC MOSFET,especially in 4 H-SiC trench MOSFET.
文摘Layered cathode materials have been successfully commercialized and applied to electric vehicles.To further improve improve the energy density of these marterials is still the main efforts in the market.Therefore,developing high-voltage LiNi_(x)Co_(y)Mn_(z)O_(2)(x+y+z=1,NCM)to achieve high energy density is particularly important.However,under high voltage cycling,NCM often exhibits rapid capacity degradation,which can be attributed to oxygen release,structural phase transition and particle cracking.In this work,the representative single-crystal LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM523)was studied under various high charge cut-off voltages.Analysis by x-ray diffraction(XRD),transmission electron microscope(TEM)and electron back scatter diffraction(EBSD)measurements indicated that the rock-salt phase is formed on the surface of the particles after high voltage cycling,which is responsible for the increase of impedance and the rapid decay of capacity.Therefore,inhibiting the formation of rock-salt phase is believed an effective strategy to address the failure of NCM under high voltages.These findings provide effective guidance for the development of high-voltage NCM.
基金supported by grant No.R01-2006-000-11275-0 (2008) from the Basic Research Program of the Korea Science & Engineering Foundation
文摘The current-voltage (I-V) curves, such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV), were employed to evaluate the effect of electrolyte concentration on the electrochemical reaction trend. From the I-V curve, the electrochemical states of active, passive, transient and trans-passive region could be characterized. And then, the mechanism of the process of voltage-induced material removal in electrochemical mechanical polishing (ECMP) of copper was investigated. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were used to observe the surface profile. Finally, the oxidation and reduction processes of the Cu surface were monitored by the repetition of anodic and cathodic potential from cyclic voltammetry (CV) method in acid-and alkali-based electrolyte.
基金Projects(51102264,51271123)supported by the National Natural Science Foundation of ChinaProjects(5313310202,13ZR1427900)supported by Shanghai Municipal Education Commission,China
文摘In order to investigate nanomechanical properties of nanostructured Ti metallic material, pure Ti films were prepared by magnetron sputtering at the bias voltage of 0-140 V. The microstructure of Ti films was characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and high-resolution transmission electron microscopy(HRTEM). It is interesting to find that the microstructure of pure Ti films was characterized by the composite structure of amorphous-like matrix embodied with nanocrystallines, and the crystallization was improved with the increase of bias voltage. The hardness of Ti films measured by nanoindentation tests shows a linear relationship with grain sizes in the scale of 6-15 nm. However, the pure Ti films exhibit a soft tendency characterized by a smaller slope of Hall-Petch relationship. In addition, the effect of bias voltage on the growth orientation of Ti films was discussed.