Electrochemical CO_(2) reduction into CO or high-value products is regarded as a feasible pathway for energy conversion,which has attracted universal attention in recent years [1-3].However,the reduction of CO_(2) mol...Electrochemical CO_(2) reduction into CO or high-value products is regarded as a feasible pathway for energy conversion,which has attracted universal attention in recent years [1-3].However,the reduction of CO_(2) molecule is a thermodynamically uphill process,which involves multiple elemental steps and the competition of hydrogen evolution reaction(HER) in aqueous solution.展开更多
The plasma sheath can induce radar signal modulation,causing not only ineffective target detection,but also defocusing in inverse synthetic aperture radar(ISAR)imaging.In this paper,through establishing radar echo mod...The plasma sheath can induce radar signal modulation,causing not only ineffective target detection,but also defocusing in inverse synthetic aperture radar(ISAR)imaging.In this paper,through establishing radar echo models of the reentry object enveloped with time-varying plasma sheath,we simulated the defocusing of ISAR images in typical environment.Simulation results suggested that the ISAR defocusing is caused by false scatterings,upon which the false scatterings’formation mechanism and distribution property are analyzed and studied.The range of false scattering correlates with the electron density fluctuation frequency.The combined value of the electron density fluctuation and the pulse repetition frequency jointly determines the Doppler of false scattering.Two measurement metrics including peak signal-to-noise ratio and structural similarity are used to evaluate the influence of ISAR imaging.展开更多
Development of efficient molecular devices for overall water splitting has always been a hotspot of research to realize clean and sustainable energy conversion. In the case, long-term durability of molecular devices i...Development of efficient molecular devices for overall water splitting has always been a hotspot of research to realize clean and sustainable energy conversion. In the case, long-term durability of molecular devices is a crucial factor to determine their practical application. Here, an efficient composite molecular anode was assembled by immobilization of charge-neutral mononuclear Ru1 complex on COOHfunctionalized multiwalled carbon nanotubes(MWCNTs COOH) sticking on a glassy carbon(GC) electrode(Ru1/MWCNTsCOOH/GC). The prepared hybrid anode showed a low onset overpotential of only 380 mV for electrocatalytic water oxidation. Moreover, the anode displayed a steady catalytic current density of1.25 mA/cm^2 for more than 5 h at the overpotential of 580 m V, a high TON of 186000(5 h), a TOF of10.3 s-1 and a faradic efficiency of 96%, indicating the significant efficiency and extremely durability.The excellent durability of the molecular anode should be attributed to the key charge-neutral catalytic intermediates(Ru1 ad) of the catalytic step and the two long flexible carbon chains of the catalyst.展开更多
Developing highly efficient and stable water oxidation catalysts based on abundant metallic elements is a challenge that must be met to fulfill the promise of water splitting for clean energy production.In this work,w...Developing highly efficient and stable water oxidation catalysts based on abundant metallic elements is a challenge that must be met to fulfill the promise of water splitting for clean energy production.In this work,we developed an oxygen evolution reaction catalyst consisting of a nanostructured film electrodeposited from a phosphate buffer solution(0.2mol/L,pH=12.0)containing Cu‐tricine complex.A Tafel plot showed that the required overpotential for a current densityof1.0mA/cm2was only395mV and the Tafel slope was46.7mV/decade.In addition,the Cu‐tricine film maintained a stable current density of7.5mA/cm2for the oxygen evolution reaction in phosphate buffer solution for10h,and a Faradaic efficiency of99%was obtained.展开更多
Two efficient single-site Ru water oxidation catalysts [Ru（bda）（pic）（Ln）] （bda=2,2＇-bipyridine- 6,6＇-dicarboxylic acid, pic=picoline, Ll=4,5-bipyridine-2,7-di-tett-butyl-9,9-dimethylxanthene, L2=4- pyridine-5...Two efficient single-site Ru water oxidation catalysts [Ru（bda）（pic）（Ln）] （bda=2,2＇-bipyridine- 6,6＇-dicarboxylic acid, pic=picoline, Ll=4,5-bipyridine-2,7-di-tett-butyl-9,9-dimethylxanthene, L2=4- pyridine-5-phenyl-2,7-di-tert-butyl-9,9-dimethylxanthene） were only synthesized containing different xanthene ligands at the axial site. These complexes have been thoroughly characterized by spectroscopic （UV-vis, NMR） and electrochemical （CV and DIV） techniques. Kinetic analysis proved that the mechanism of water oxidation comprises the water nucleophilic attack process on high-valence ruthenium species. It is found that the catalyst I displayed higher activity than catalyst 2 on water oxidation, caused by the protonation of the axial ligand LI with a free pyridine.展开更多
The scattering points in a plasma sheath characterized with coupled velocities can cause pulse compression mismatching,which results in displacement and energy diffusion in the onedimension range profile.To solve this...The scattering points in a plasma sheath characterized with coupled velocities can cause pulse compression mismatching,which results in displacement and energy diffusion in the onedimension range profile.To solve this problem,we deduce the echo model of the plasma-sheathenveloped reentry object.By estimating the coupled velocities,we propose a compensation method to correct the defocus of an inverse synthetic aperture radar(ISAR)image in range dimension to improve the quality of the ISAR images.The simulation results suggest that the echoes from different regions of the surface of the reentry object have various coupling velocities,and the higher the coupled velocity,the more serious the displacement and energy diffusion in the range dimension.Our proposed method can correct the range dimension aberration.Two measurement metrics were used to evaluate the improvement of the compensation method.展开更多
The Visual tracking problem can usually be solved in two parts.The first part is to extract the feature of the target and get the candidate region.The second part is to realize the classification of the target and the...The Visual tracking problem can usually be solved in two parts.The first part is to extract the feature of the target and get the candidate region.The second part is to realize the classification of the target and the regression of the bounding box.In recent years,Siameses network in visual tracking problem has always been a frontier research hotspot.In this work,it applies two branches namely search area and tracking template area for similar learning to track.Some related researches prove the feasibility of this network structure.According to the characteristics of two branch shared networks in Siamese network,we also propos a new fully convolutional Siamese network to solve the visual tracking problem.Based on the Siamese network structure,the network we designed adopt a new fusion module,which realizes the fusion of multiple feature layers at different depths.We also devise a better target state estimation criterion.The overall structure is simple,efficient and has wide applicability.We extensive experiments on challenging benchmarks including generic object tracking-10k(GOT-10K),online object tracking benckmark2015(OTB2015)and unmanned air vehicle123(UAV123),and comparisons with state-of-the-art trackers and the fusion module commonly used in the past,Finally,our network performed better under the same backbone,and achieved good tracking effect,which proved the effectiveness and universality of our designed network and feature fusion method.展开更多
A plasma-based stable,ultra-wideband electromagnetic（EM） wave absorber structure is studied in this paper for stealth applications.The stability is maintained by a multi-layer structure with several plasma layers an...A plasma-based stable,ultra-wideband electromagnetic（EM） wave absorber structure is studied in this paper for stealth applications.The stability is maintained by a multi-layer structure with several plasma layers and dielectric layers distributed alternately.The plasma in each plasma layer is designed to be uniform,whereas it has a discrete nonuniform distribution from the overall view of the structure.The nonuniform distribution of the plasma is the key to obtaining ultra-wideband wave absorption.A discrete Epstein distribution model is put forward to constrain the nonuniform electron density of the plasma layers,by which the wave absorption range is extended to the ultra-wideband.Then,the scattering matrix method（SMM） is employed to analyze the electromagnetic reflection and absorption of the absorber structure.In the simulation,the validation of the proposed structure and model in ultra-wideband EM wave absorption is first illustrated by comparing the nonuniform plasma model with the uniform case.Then,the influence of various parameters on the EM wave reflection of the plasma are simulated and analyzed in detail,verifying the EM wave absorption performance of the absorber.The proposed structure and model are expected to be superior in some realistic applications,such as supersonic aircraft.展开更多
Lipid metabolism disorders contribute to hyperlipidemia and hepatic steatosis.It is ideal to develop drugs simultaneous improving both hyperlipidemia and hepatic steatosis.Nitazoxanide is an FDA-approved oral antiprot...Lipid metabolism disorders contribute to hyperlipidemia and hepatic steatosis.It is ideal to develop drugs simultaneous improving both hyperlipidemia and hepatic steatosis.Nitazoxanide is an FDA-approved oral antiprotozoal drug with excellent pharmacokinetic and safety profile.We found that nitazoxanide and its metabolite tizoxanide induced mild mitochondrial uncoupling and subsequently activated AMPK in Hep G2 cells.Gavage administration of nitazoxanide inhibited high-fat diet(HFD)-induced increases of liver weight,blood and liver lipids,and ameliorated HFD-induced renal lipid accumulation in hamsters.Nitazoxanide significantly improved HFD-induced histopathologic changes of hamster livers.In the hamsters with pre-existing hyperlipidemia and hepatic steatosis,nitazoxanide also showed therapeutic effect.Gavage administration of nitazoxanide improved HFD-induced hepatic steatosis in C57BL/6J mice and western diet(WD)-induced hepatic steatosis in Apoe-/-mice.The present study suggests that repurposing nitazoxanide as a drug for hyperlipidemia and hepatic steatosis treatment is promising.展开更多
基金supported by the National Natural Science Foundation of China(21875030,21908120)the Liaoning Excellent Talents in University(LR2019016)。
文摘Electrochemical CO_(2) reduction into CO or high-value products is regarded as a feasible pathway for energy conversion,which has attracted universal attention in recent years [1-3].However,the reduction of CO_(2) molecule is a thermodynamically uphill process,which involves multiple elemental steps and the competition of hydrogen evolution reaction(HER) in aqueous solution.
基金supported in part by National Natural Science Foundation of China(Nos.61971330,61701381,and 61627901)in part by the Natural Science Basic Research Plan in Shaanxi Province of China(No.2019JM-177)in part by the Chinese Postdoctoral Science Foundation。
文摘The plasma sheath can induce radar signal modulation,causing not only ineffective target detection,but also defocusing in inverse synthetic aperture radar(ISAR)imaging.In this paper,through establishing radar echo models of the reentry object enveloped with time-varying plasma sheath,we simulated the defocusing of ISAR images in typical environment.Simulation results suggested that the ISAR defocusing is caused by false scatterings,upon which the false scatterings’formation mechanism and distribution property are analyzed and studied.The range of false scattering correlates with the electron density fluctuation frequency.The combined value of the electron density fluctuation and the pulse repetition frequency jointly determines the Doppler of false scattering.Two measurement metrics including peak signal-to-noise ratio and structural similarity are used to evaluate the influence of ISAR imaging.
基金supported by the National Natural Science Foundation of China(21573033,21875030)the National Basic Research Program of China(973 program,2014CB239402)+1 种基金the Fundamental Research Funds for the Central Universities(DUT18ZD210)the State Key Laboratory of Fine Chemicals(KF1610)
文摘Development of efficient molecular devices for overall water splitting has always been a hotspot of research to realize clean and sustainable energy conversion. In the case, long-term durability of molecular devices is a crucial factor to determine their practical application. Here, an efficient composite molecular anode was assembled by immobilization of charge-neutral mononuclear Ru1 complex on COOHfunctionalized multiwalled carbon nanotubes(MWCNTs COOH) sticking on a glassy carbon(GC) electrode(Ru1/MWCNTsCOOH/GC). The prepared hybrid anode showed a low onset overpotential of only 380 mV for electrocatalytic water oxidation. Moreover, the anode displayed a steady catalytic current density of1.25 mA/cm^2 for more than 5 h at the overpotential of 580 m V, a high TON of 186000(5 h), a TOF of10.3 s-1 and a faradic efficiency of 96%, indicating the significant efficiency and extremely durability.The excellent durability of the molecular anode should be attributed to the key charge-neutral catalytic intermediates(Ru1 ad) of the catalytic step and the two long flexible carbon chains of the catalyst.
文摘Developing highly efficient and stable water oxidation catalysts based on abundant metallic elements is a challenge that must be met to fulfill the promise of water splitting for clean energy production.In this work,we developed an oxygen evolution reaction catalyst consisting of a nanostructured film electrodeposited from a phosphate buffer solution(0.2mol/L,pH=12.0)containing Cu‐tricine complex.A Tafel plot showed that the required overpotential for a current densityof1.0mA/cm2was only395mV and the Tafel slope was46.7mV/decade.In addition,the Cu‐tricine film maintained a stable current density of7.5mA/cm2for the oxygen evolution reaction in phosphate buffer solution for10h,and a Faradaic efficiency of99%was obtained.
基金supported by the National Basic Research Program of China (973 program, 2014CB239402)the National Natural Science Foundation of China (21573033)the Basic Research Project of Key Laboratory of Liaoning (LZ2015015)
文摘Two efficient single-site Ru water oxidation catalysts [Ru（bda）（pic）（Ln）] （bda=2,2＇-bipyridine- 6,6＇-dicarboxylic acid, pic=picoline, Ll=4,5-bipyridine-2,7-di-tett-butyl-9,9-dimethylxanthene, L2=4- pyridine-5-phenyl-2,7-di-tert-butyl-9,9-dimethylxanthene） were only synthesized containing different xanthene ligands at the axial site. These complexes have been thoroughly characterized by spectroscopic （UV-vis, NMR） and electrochemical （CV and DIV） techniques. Kinetic analysis proved that the mechanism of water oxidation comprises the water nucleophilic attack process on high-valence ruthenium species. It is found that the catalyst I displayed higher activity than catalyst 2 on water oxidation, caused by the protonation of the axial ligand LI with a free pyridine.
基金supported by National Natural Science Foundation of China(No.61971330)。
文摘The scattering points in a plasma sheath characterized with coupled velocities can cause pulse compression mismatching,which results in displacement and energy diffusion in the onedimension range profile.To solve this problem,we deduce the echo model of the plasma-sheathenveloped reentry object.By estimating the coupled velocities,we propose a compensation method to correct the defocus of an inverse synthetic aperture radar(ISAR)image in range dimension to improve the quality of the ISAR images.The simulation results suggest that the echoes from different regions of the surface of the reentry object have various coupling velocities,and the higher the coupled velocity,the more serious the displacement and energy diffusion in the range dimension.Our proposed method can correct the range dimension aberration.Two measurement metrics were used to evaluate the improvement of the compensation method.
文摘The Visual tracking problem can usually be solved in two parts.The first part is to extract the feature of the target and get the candidate region.The second part is to realize the classification of the target and the regression of the bounding box.In recent years,Siameses network in visual tracking problem has always been a frontier research hotspot.In this work,it applies two branches namely search area and tracking template area for similar learning to track.Some related researches prove the feasibility of this network structure.According to the characteristics of two branch shared networks in Siamese network,we also propos a new fully convolutional Siamese network to solve the visual tracking problem.Based on the Siamese network structure,the network we designed adopt a new fusion module,which realizes the fusion of multiple feature layers at different depths.We also devise a better target state estimation criterion.The overall structure is simple,efficient and has wide applicability.We extensive experiments on challenging benchmarks including generic object tracking-10k(GOT-10K),online object tracking benckmark2015(OTB2015)and unmanned air vehicle123(UAV123),and comparisons with state-of-the-art trackers and the fusion module commonly used in the past,Finally,our network performed better under the same backbone,and achieved good tracking effect,which proved the effectiveness and universality of our designed network and feature fusion method.
基金supported in part by the National Basic Research Program of China (grant no.2014CB340205)in part by the Science and Technology on Space Physics Laboratory Fundsin part by the Fundamental Research Funds for the Central Universities (20101156180)
文摘A plasma-based stable,ultra-wideband electromagnetic（EM） wave absorber structure is studied in this paper for stealth applications.The stability is maintained by a multi-layer structure with several plasma layers and dielectric layers distributed alternately.The plasma in each plasma layer is designed to be uniform,whereas it has a discrete nonuniform distribution from the overall view of the structure.The nonuniform distribution of the plasma is the key to obtaining ultra-wideband wave absorption.A discrete Epstein distribution model is put forward to constrain the nonuniform electron density of the plasma layers,by which the wave absorption range is extended to the ultra-wideband.Then,the scattering matrix method（SMM） is employed to analyze the electromagnetic reflection and absorption of the absorber structure.In the simulation,the validation of the proposed structure and model in ultra-wideband EM wave absorption is first illustrated by comparing the nonuniform plasma model with the uniform case.Then,the influence of various parameters on the EM wave reflection of the plasma are simulated and analyzed in detail,verifying the EM wave absorption performance of the absorber.The proposed structure and model are expected to be superior in some realistic applications,such as supersonic aircraft.
基金supported by the National Natural Science Foundation of China(Nos.81773725 and 91739102)。
文摘Lipid metabolism disorders contribute to hyperlipidemia and hepatic steatosis.It is ideal to develop drugs simultaneous improving both hyperlipidemia and hepatic steatosis.Nitazoxanide is an FDA-approved oral antiprotozoal drug with excellent pharmacokinetic and safety profile.We found that nitazoxanide and its metabolite tizoxanide induced mild mitochondrial uncoupling and subsequently activated AMPK in Hep G2 cells.Gavage administration of nitazoxanide inhibited high-fat diet(HFD)-induced increases of liver weight,blood and liver lipids,and ameliorated HFD-induced renal lipid accumulation in hamsters.Nitazoxanide significantly improved HFD-induced histopathologic changes of hamster livers.In the hamsters with pre-existing hyperlipidemia and hepatic steatosis,nitazoxanide also showed therapeutic effect.Gavage administration of nitazoxanide improved HFD-induced hepatic steatosis in C57BL/6J mice and western diet(WD)-induced hepatic steatosis in Apoe-/-mice.The present study suggests that repurposing nitazoxanide as a drug for hyperlipidemia and hepatic steatosis treatment is promising.
