Lithium-sulfur batteries are regarded as promising next-generation energy storage batteries for their ultra-high theoretical energy density.However,the complex sulfur electrode process with sluggish sulfur conversion ...Lithium-sulfur batteries are regarded as promising next-generation energy storage batteries for their ultra-high theoretical energy density.However,the complex sulfur electrode process with sluggish sulfur conversion reactions is a critical issue for lithiumsulfur batteries,in which catalytic interfacial reactions and accelerated lithium-ion diffusion are the key factors.Our previous work has shown that implanting functional molecules with multiple redox properties in the electrode can break through the conventional diffusion layer constraints and achieve forced convection.In this work,a functionalized complex molecule,methylene blue anthraquinone-2-sulfonate(MB-AQ),with multiple redox activities as well as abundant active sites,was synthesized and introduced into the sulfur cathode.In addition to accelerating the transport of lithium ions by reversible inhaling and exhaling lithium ions,the MB-AQ can combine polysulfides by its active sites to accelerate sulfur conversion reactions.Benefiting from two functions of accelerating ion diffusion and catalyzing interfacial reactions,MB-AQ/reduced graphene oxide(rGO)/S cathode can achieve high initial capacities of 884 and 674 mAh·g^(−1)with stable cycling of 700 and 1,000 times at 1 and 4 C,respectively.It is worth mentioning that the capacity of 462 mAh·g^(−1)can be achieved even at a high current density of 6 C.This work provides a new approach to enhancing the sulfur cathode process.展开更多
The aim of the present study was to develop tamsulosin hydrochloride sustained-release pellets using two-layered membrane techniques.Centrifugal granulator and fluidizedbed coater were employed to prepare drug-loaded ...The aim of the present study was to develop tamsulosin hydrochloride sustained-release pellets using two-layered membrane techniques.Centrifugal granulator and fluidizedbed coater were employed to prepare drug-loaded pellets and to employ two-layered membrane coating respectively.The prepared pellets were evaluated for physicochemical characterization,subjected to differential scanning calorimetry(DSC)and in vitro release of different pH.Different release models and scanning electron microscopy(SEM)were utilized to analyze the release mechanism of Harnual■ and home-made pellets.By comparing the dissolution profiles,the ratio and coating weight gain of Eudragit■ NE30D and Eudragit■ L30D55 which constitute the inside membrane were identified as 18:1 and 10%-11%.The coating amount of outside membrane containing Eudragit■ L30D55 was determined to be 0.8%.The similarity factors(f_(2))of home-made capsule and commercially available product(Harnual■)were above 50 in different dissolution media.DSC studies confirmed that drug and excipients had good compatibility and SEM photographs showed the similarities and differences of coating surface between Harnual■ and self-made pellets before and after dissolution.According to Ritger-Peppas model,the two dosage form had different release mechanism.展开更多
Superjunction technology is believed to reach the optimal specific on-resistance and breakdown voltage trade-off.It has become a mainstream technology in silicon high-voltage metal oxide semiconductor field effect tra...Superjunction technology is believed to reach the optimal specific on-resistance and breakdown voltage trade-off.It has become a mainstream technology in silicon high-voltage metal oxide semiconductor field effect transistor devices.Numerous efforts have been conducted to employ the same concept in silicon carbide devices.These works are summarized here.展开更多
As the fundamental energy storage components in electronic systems,dielectric capacitors with high power densities were demanded.In this work,the anti-ferroelectric Pb_(0.89)La_(0.06)Sr_(0.05)(Zr_(0.95)Ti_(0.05))O_(3)...As the fundamental energy storage components in electronic systems,dielectric capacitors with high power densities were demanded.In this work,the anti-ferroelectric Pb_(0.89)La_(0.06)Sr_(0.05)(Zr_(0.95)Ti_(0.05))O_(3)(PLSZT)ceramics and thin film capacitor were successfully fabricated by a solid-state reaction route and pulsed laser deposition method,respectively.The ferroelectric,dielectric,energy-storage properties,and temperature stability of anti-ferroelectric PLSZT capacitor were investigated in detail.By compared with the PLSZT ceramic(energy storage density is 1.29 J/cm^(3) with an efficiency of 78.7%under 75 kV/cm),the anti-ferroelectric PLSZT thin film capacitors exhibited the enhanced energy storage density of 52.6 J/cm^(3) with efficiency of 67.7%under an electric field as high as 2068.9 kV/cm,and the enhanced energy-storage temperature stabilities from room temperature(RT)to more than 200℃ were demonstrated,and the oxygen defects mechanism and size effect were discussed.Moreover,the fast charging(~0.05 μs)and discharging(~0.15 μs)time were certified for the anti-ferroelectric PLSZT film capacitor.These findings broaden the horizon for PLSZT anti-ferroelectrics in high energy storage properties and show promising for manufacturing pulse power capacitor.展开更多
The feature extraction and pattern recognition techniques are of great importance to assess the insulation condition of gas-insulated switchgear.In this work,the ultra-high-frequency partial discharge(PD)signals gener...The feature extraction and pattern recognition techniques are of great importance to assess the insulation condition of gas-insulated switchgear.In this work,the ultra-high-frequency partial discharge(PD)signals generated from four types of typical insulation defects are analysed using S-transform,and the greyscale image in time-frequency representation is divided into five regions according to the cutoff frequencies of TEm1 modes.Then,the three low-order moments of every subregion are extracted and the feature selection is performed based on the J criterion.To confirm the effectiveness of selected moment features after considering the electromagnetic modes,the support vector machine,k-nearest neighbour and particle swarm-optimised extreme learning machine(ELM)are utilised to classify the type of PD,and they achieve the recognition accuracies of 92,88.5 and 95%,respectively.In addition,the results show that the ELM offers good generalisation performance at the fastest learning and testing speeds,thus more suitable for a real-time PD detection.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U1805254,21773192,22072117,and 22179112).
文摘Lithium-sulfur batteries are regarded as promising next-generation energy storage batteries for their ultra-high theoretical energy density.However,the complex sulfur electrode process with sluggish sulfur conversion reactions is a critical issue for lithiumsulfur batteries,in which catalytic interfacial reactions and accelerated lithium-ion diffusion are the key factors.Our previous work has shown that implanting functional molecules with multiple redox properties in the electrode can break through the conventional diffusion layer constraints and achieve forced convection.In this work,a functionalized complex molecule,methylene blue anthraquinone-2-sulfonate(MB-AQ),with multiple redox activities as well as abundant active sites,was synthesized and introduced into the sulfur cathode.In addition to accelerating the transport of lithium ions by reversible inhaling and exhaling lithium ions,the MB-AQ can combine polysulfides by its active sites to accelerate sulfur conversion reactions.Benefiting from two functions of accelerating ion diffusion and catalyzing interfacial reactions,MB-AQ/reduced graphene oxide(rGO)/S cathode can achieve high initial capacities of 884 and 674 mAh·g^(−1)with stable cycling of 700 and 1,000 times at 1 and 4 C,respectively.It is worth mentioning that the capacity of 462 mAh·g^(−1)can be achieved even at a high current density of 6 C.This work provides a new approach to enhancing the sulfur cathode process.
文摘The aim of the present study was to develop tamsulosin hydrochloride sustained-release pellets using two-layered membrane techniques.Centrifugal granulator and fluidizedbed coater were employed to prepare drug-loaded pellets and to employ two-layered membrane coating respectively.The prepared pellets were evaluated for physicochemical characterization,subjected to differential scanning calorimetry(DSC)and in vitro release of different pH.Different release models and scanning electron microscopy(SEM)were utilized to analyze the release mechanism of Harnual■ and home-made pellets.By comparing the dissolution profiles,the ratio and coating weight gain of Eudragit■ NE30D and Eudragit■ L30D55 which constitute the inside membrane were identified as 18:1 and 10%-11%.The coating amount of outside membrane containing Eudragit■ L30D55 was determined to be 0.8%.The similarity factors(f_(2))of home-made capsule and commercially available product(Harnual■)were above 50 in different dissolution media.DSC studies confirmed that drug and excipients had good compatibility and SEM photographs showed the similarities and differences of coating surface between Harnual■ and self-made pellets before and after dissolution.According to Ritger-Peppas model,the two dosage form had different release mechanism.
基金supported by the National Key Research and Development Program(No.2016YFB0400500)the Key Research and Development Projects in Guangdong Province(No.2019B010144001)。
文摘Superjunction technology is believed to reach the optimal specific on-resistance and breakdown voltage trade-off.It has become a mainstream technology in silicon high-voltage metal oxide semiconductor field effect transistor devices.Numerous efforts have been conducted to employ the same concept in silicon carbide devices.These works are summarized here.
基金financially supported by National Natural Science Foundation of China(NSFC)(Grant Nos.51702055,62073084,11904056,and 51604087)the Guangdong Provincial Natural Science Foundation of China(Grant No.2016A030313718)+1 种基金the Science and Technology Program of Guangdong Province of China(Grant Nos.2016A010104018 and 2017A010104022)Special Funds for the Cultivation of Guangdong College Students’Scientific and Technological Innovation(Climbing Program Special Funds,Grant No.pdjh2020a0174,pdjh2019a0147).
文摘As the fundamental energy storage components in electronic systems,dielectric capacitors with high power densities were demanded.In this work,the anti-ferroelectric Pb_(0.89)La_(0.06)Sr_(0.05)(Zr_(0.95)Ti_(0.05))O_(3)(PLSZT)ceramics and thin film capacitor were successfully fabricated by a solid-state reaction route and pulsed laser deposition method,respectively.The ferroelectric,dielectric,energy-storage properties,and temperature stability of anti-ferroelectric PLSZT capacitor were investigated in detail.By compared with the PLSZT ceramic(energy storage density is 1.29 J/cm^(3) with an efficiency of 78.7%under 75 kV/cm),the anti-ferroelectric PLSZT thin film capacitors exhibited the enhanced energy storage density of 52.6 J/cm^(3) with efficiency of 67.7%under an electric field as high as 2068.9 kV/cm,and the enhanced energy-storage temperature stabilities from room temperature(RT)to more than 200℃ were demonstrated,and the oxygen defects mechanism and size effect were discussed.Moreover,the fast charging(~0.05 μs)and discharging(~0.15 μs)time were certified for the anti-ferroelectric PLSZT film capacitor.These findings broaden the horizon for PLSZT anti-ferroelectrics in high energy storage properties and show promising for manufacturing pulse power capacitor.
基金the National Natural Science Foundation of China(No.51677061,51507058).
文摘The feature extraction and pattern recognition techniques are of great importance to assess the insulation condition of gas-insulated switchgear.In this work,the ultra-high-frequency partial discharge(PD)signals generated from four types of typical insulation defects are analysed using S-transform,and the greyscale image in time-frequency representation is divided into five regions according to the cutoff frequencies of TEm1 modes.Then,the three low-order moments of every subregion are extracted and the feature selection is performed based on the J criterion.To confirm the effectiveness of selected moment features after considering the electromagnetic modes,the support vector machine,k-nearest neighbour and particle swarm-optimised extreme learning machine(ELM)are utilised to classify the type of PD,and they achieve the recognition accuracies of 92,88.5 and 95%,respectively.In addition,the results show that the ELM offers good generalisation performance at the fastest learning and testing speeds,thus more suitable for a real-time PD detection.
