The Earth’s Free Core Nutation(FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance effects.High-precision superconducting gravimeter(SG) and very long baseline interfe...The Earth’s Free Core Nutation(FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance effects.High-precision superconducting gravimeter(SG) and very long baseline interferometry(VLBI) provide good observation techniques for detecting the FCN parameters.However,some choices in data processing and solution procedures increase the uncertainty of the FCN parameters.In this study,we analyzed the differences and the effectiveness of weight function and ocean tide corrections in the FCN parameter detection using synthetic data,SG data from thirty-one stations,and the 10 celestial pole offset(CPO) series.The results show that significant discrepancies are caused by different computing options for a single SG station.The stacking method,which results in a variation of0.24-5 sidereal days(SDs) in the FCN period(T) and 10^(3)-10^(4) in the quality factor(Q) due to the selection of the weighting function and the ocean tide model(OTM),can effectively suppress this influence.The statistical analysis results of synthetic data shows that although different weight choices,while adjusting the proportion of diurnal tidal waves involved,do not significantly improve the accuracy of fitted FCN parameters from gravity observations.The study evaluated a series of OTMs using the loading correction efficiency.The fitting of FCN parameters can be improved by selecting the mean of appropriate OTMs based on the evaluation results.Through the estimation of the FCN parameters based on the forced nutation,it was found that the weight function P_(1) is more suitable than others,and different CPO series(after 2009) resulted in a difference of 0.4 SDs in the T and of 103 in the Q.We estimated the FCN parameters for SG(T=430.4±1.5 SDs and Q=1.52×10^(4)±2.5×10^(3)) and for VLBI(T=429.8±0.7 SDs,Q=1.88×10^(4)±2.1×10^(3)).展开更多
Li-O_(2) batteries provide an attractive and potential strategy for energy conversion and storage with high specific energy densities.However,large over-potential in oxygen evolution reactions (OER) caused by the deco...Li-O_(2) batteries provide an attractive and potential strategy for energy conversion and storage with high specific energy densities.However,large over-potential in oxygen evolution reactions (OER) caused by the decomposition obstacles of Li_(2)O_(2) seriously impedes its electrochemical performances.Herein,a novel N,O,S and F co-doping vesicular carbon was prepared by self-template pyrolysis method and used in LiO_(2) battery to tune the nucleation and decomposition of Li_(2)O_(2).The introduction of F in the carbon matrix with suitable content can regulate the adsorption of intermediates,through which the morphology of Li_(2)O_(2) can be controlled to film,favorable to its decomposition in charge process.The cathode based on the optimized F doped carbon vesicle exhibits improved electrochemical performances including a low over-potential,large capacity and a long-term stability.Density functional theory (DFT) results show that F and C in C–F bond hasve a strong interaction to Li and O in Li_(2)O_(2),respectively,which can enhance the transfer of electrons from Li_(2)O_(2) to the carbon matrix to generate hole polaron and thus accelerate the delithiation and decomposition of Li_(2)O_(2).This work provides a new sight into understanding the mechanism of nucleation and decomposition of Li_(2)O_(2) for the development of high-performance Li-O_(2) batteries.展开更多
Li-CO_(2) batteries provide an attractive and potential strategy for CO_(2) utilization as well as energy conversion and storage with high specific energy densities.However,the poor reversibility caused by the decompo...Li-CO_(2) batteries provide an attractive and potential strategy for CO_(2) utilization as well as energy conversion and storage with high specific energy densities.However,the poor reversibility caused by the decomposition obstacles of Li_(2)CO_(3) and C products is still a challenge for Li-CO_(2) batteries,which seriously influences its electrochemical performances.Herein,a free-standing MnOOH arrays cathode has been prepared and employed in Li-CO_(2) battery,which realizes a great improvement of electrochemical performances by adjusting the discharge products distribution.Experiments coupled with theoretical calculations verifies that the formation of Li-containing carbonaceous species(LiCO_(2),LiCO and Li_(2) CO_(3))bonded with MnOOH through Li ion regulates the nucleation behavior of Li_(2)CO_(3) and C,making them grown on MnOOH uniformly.The fine Li_(2) CO_(3) grains(with a size about 5 nm)embedded into carbon matrix greatly enlarges the contact interface between them,facilitating the transmission of electrons through the discharge products and finally improves CO_(2) evolution activity.This ingenious design strategy of regulating discharge products distribution to improve electrochemical performances provides a promising way to develop advanced Li-CO_(2) batteries.展开更多
Hierarchical Co3O4 porous nanowires （NWs） have been synthesized using a hydrothermal method followed by calcination. When employed as a cathode catalyst in non-aqueous Li-oxygen batteries, the Co3O4 NWs effectively ...Hierarchical Co3O4 porous nanowires （NWs） have been synthesized using a hydrothermal method followed by calcination. When employed as a cathode catalyst in non-aqueous Li-oxygen batteries, the Co3O4 NWs effectively improve both the round-trip efficiency and cycling stability, which can be attributed to the high catalytic activities of Co3O4 NWs for the oxygen reduction reaction and the oxygen evolution reaction during discharge and charge processes, respectively.展开更多
Nowadays,the deep learning for object detection has become more popular and is widely adopted in many fields.This paper focuses on the research of LiDAR and camera sensor fusion technology for vehicle detection to ens...Nowadays,the deep learning for object detection has become more popular and is widely adopted in many fields.This paper focuses on the research of LiDAR and camera sensor fusion technology for vehicle detection to ensure extremely high detection accuracy.The proposed network architecture takes full advantage of the deep information of both the LiDAR point cloud and RGB image in object detection.First,the LiDAR point cloud and RGB image are fed into the system.Then a high-resolution feature map is used to generate a reliable 3D object proposal for both the LiDAR point cloud and RGB image.Finally,3D box regression is performed to predict the extent and orientation of vehicles in 3D space.Experiments on the challenging KITTI benchmark show that the proposed approach obtains ideal detection results and the detection time of each frame is about 0.12 s.This approach could establish a basis for further research in autonomous vehicles.展开更多
of main observation and conclusion We have achieved the total synthesis of an architecturally and biologically intriguing cyclic polypeptide,rhizonin A(1);in an exceptionally concise and convergent fashion.The strateg...of main observation and conclusion We have achieved the total synthesis of an architecturally and biologically intriguing cyclic polypeptide,rhizonin A(1);in an exceptionally concise and convergent fashion.The strategic route entails 9 longest linear steps to elaborate commercially available materials into the natural product with an overall yield of 9.7%.The brevity of sequence and high overall yield was fueled by the judicious selection of chemical tactics.Rhizonin A(1)showed weak inhibitory effects on the cell viability of HCT116 colorectal cancer cells and this activity was dependent on hypoxia-inducible factors.展开更多
Aprotic Li-CO_(2)batteries have attracted growing interest due to their high theoretical energy density and its ability to use green house gas CO_(2)for energy storage.However,the poor ability of activating CO_(2)in o...Aprotic Li-CO_(2)batteries have attracted growing interest due to their high theoretical energy density and its ability to use green house gas CO_(2)for energy storage.However,the poor ability of activating CO_(2)in organic electrolyte often leads to the premature termination of CO_(2)reduction reaction(CO_(2)RR)directly.Here in this work,cetyl trimethyl ammonium bromide(CTAB)was introduced into a dimethyl sulfoxide(DMSO)based Li-CO_(2)battery for the first time to enhance the CO_(2)RR.Significantly improved electrochemical performances,including reduced discharge over-potential and increased discharge capacity,can be achieved with the addition of CTAB.Ab initio molecular dynamics(AIMD)simulations show that quaternary ammonium group CTA^(+) can accelerate CO_(2)reduction process by forming more stable contact ion pair(CIP)with CO_(2)^(–),reducing the energy barrier for CO_(2)RR,thus improving the CO_(2)reduction process.In addition,adding CTA^(+) is also favorable for the solution-phase growth of discharge products because of the improved migration ability of stable CTA^(+)-CO_(2)^(–) CIP in the electrolyte,which is beneficial for improving the utilization ratio of cathode.This work could facilitate the development of CO_(2)RR by providing a novel understanding of CO_(2)RR mechanism in organic system.展开更多
基金supported by the Open Fund of Hubei Luojia Laboratory (No. 220100033)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB41000000)+1 种基金National Natural Science Foundation of China (Grant Nos. 42174108, 41874094, 42192535 and 42242015)the Young Top-notch Talent Cultivation Program of Hubei Province。
文摘The Earth’s Free Core Nutation(FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance effects.High-precision superconducting gravimeter(SG) and very long baseline interferometry(VLBI) provide good observation techniques for detecting the FCN parameters.However,some choices in data processing and solution procedures increase the uncertainty of the FCN parameters.In this study,we analyzed the differences and the effectiveness of weight function and ocean tide corrections in the FCN parameter detection using synthetic data,SG data from thirty-one stations,and the 10 celestial pole offset(CPO) series.The results show that significant discrepancies are caused by different computing options for a single SG station.The stacking method,which results in a variation of0.24-5 sidereal days(SDs) in the FCN period(T) and 10^(3)-10^(4) in the quality factor(Q) due to the selection of the weighting function and the ocean tide model(OTM),can effectively suppress this influence.The statistical analysis results of synthetic data shows that although different weight choices,while adjusting the proportion of diurnal tidal waves involved,do not significantly improve the accuracy of fitted FCN parameters from gravity observations.The study evaluated a series of OTMs using the loading correction efficiency.The fitting of FCN parameters can be improved by selecting the mean of appropriate OTMs based on the evaluation results.Through the estimation of the FCN parameters based on the forced nutation,it was found that the weight function P_(1) is more suitable than others,and different CPO series(after 2009) resulted in a difference of 0.4 SDs in the T and of 103 in the Q.We estimated the FCN parameters for SG(T=430.4±1.5 SDs and Q=1.52×10^(4)±2.5×10^(3)) and for VLBI(T=429.8±0.7 SDs,Q=1.88×10^(4)±2.1×10^(3)).
基金financially supported by the National Natural Science Foundation of China(Grant No.21701145)the China Postdoctoral Science Foundation(Grant Nos.2017M610459,2018T110739)。
文摘Li-O_(2) batteries provide an attractive and potential strategy for energy conversion and storage with high specific energy densities.However,large over-potential in oxygen evolution reactions (OER) caused by the decomposition obstacles of Li_(2)O_(2) seriously impedes its electrochemical performances.Herein,a novel N,O,S and F co-doping vesicular carbon was prepared by self-template pyrolysis method and used in LiO_(2) battery to tune the nucleation and decomposition of Li_(2)O_(2).The introduction of F in the carbon matrix with suitable content can regulate the adsorption of intermediates,through which the morphology of Li_(2)O_(2) can be controlled to film,favorable to its decomposition in charge process.The cathode based on the optimized F doped carbon vesicle exhibits improved electrochemical performances including a low over-potential,large capacity and a long-term stability.Density functional theory (DFT) results show that F and C in C–F bond hasve a strong interaction to Li and O in Li_(2)O_(2),respectively,which can enhance the transfer of electrons from Li_(2)O_(2) to the carbon matrix to generate hole polaron and thus accelerate the delithiation and decomposition of Li_(2)O_(2).This work provides a new sight into understanding the mechanism of nucleation and decomposition of Li_(2)O_(2) for the development of high-performance Li-O_(2) batteries.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.21701145 and 21701146,21671176)China Postdoctoral Science Foundation(Grant Nos.2017M610459 and 2018T110739)。
文摘Li-CO_(2) batteries provide an attractive and potential strategy for CO_(2) utilization as well as energy conversion and storage with high specific energy densities.However,the poor reversibility caused by the decomposition obstacles of Li_(2)CO_(3) and C products is still a challenge for Li-CO_(2) batteries,which seriously influences its electrochemical performances.Herein,a free-standing MnOOH arrays cathode has been prepared and employed in Li-CO_(2) battery,which realizes a great improvement of electrochemical performances by adjusting the discharge products distribution.Experiments coupled with theoretical calculations verifies that the formation of Li-containing carbonaceous species(LiCO_(2),LiCO and Li_(2) CO_(3))bonded with MnOOH through Li ion regulates the nucleation behavior of Li_(2)CO_(3) and C,making them grown on MnOOH uniformly.The fine Li_(2) CO_(3) grains(with a size about 5 nm)embedded into carbon matrix greatly enlarges the contact interface between them,facilitating the transmission of electrons through the discharge products and finally improves CO_(2) evolution activity.This ingenious design strategy of regulating discharge products distribution to improve electrochemical performances provides a promising way to develop advanced Li-CO_(2) batteries.
文摘Hierarchical Co3O4 porous nanowires （NWs） have been synthesized using a hydrothermal method followed by calcination. When employed as a cathode catalyst in non-aqueous Li-oxygen batteries, the Co3O4 NWs effectively improve both the round-trip efficiency and cycling stability, which can be attributed to the high catalytic activities of Co3O4 NWs for the oxygen reduction reaction and the oxygen evolution reaction during discharge and charge processes, respectively.
基金This work was supported by the National Key Research and Development Program of China(2017YFB0102603,2018YFB0105003)the National Natural Science Foundation of China(51875255,61601203,61773184,U1564201,U1664258,U1764257,U1762264)+3 种基金the Natural Science Foundation of Jiangsu Province(BK20180100)the Six Talent Peaks Project of Jiangsu Province(2018-TD-GDZB-022)the Key Project for the Development of Strategic Emerging Industries of Jiangsu Province(2016-1094)the Key Research and Development Program of Zhenjiang City(GY2017006).
文摘Nowadays,the deep learning for object detection has become more popular and is widely adopted in many fields.This paper focuses on the research of LiDAR and camera sensor fusion technology for vehicle detection to ensure extremely high detection accuracy.The proposed network architecture takes full advantage of the deep information of both the LiDAR point cloud and RGB image in object detection.First,the LiDAR point cloud and RGB image are fed into the system.Then a high-resolution feature map is used to generate a reliable 3D object proposal for both the LiDAR point cloud and RGB image.Finally,3D box regression is performed to predict the extent and orientation of vehicles in 3D space.Experiments on the challenging KITTI benchmark show that the proposed approach obtains ideal detection results and the detection time of each frame is about 0.12 s.This approach could establish a basis for further research in autonomous vehicles.
基金Weacknowledge financial support from the National Natural Science Foundation of China(Nos.21772009,21901013)the Shenzhen Peacock Plan(No.KQTD2015071714043444)+1 种基金the Shenzhen Science and Technology Innovation Commission(Nos.JCYJ20170818090017617,JCYJ20170818090238288)the GDNSF(No.2014B030301003).We thank Dr.Long Dang for kindly providing the isogenic HCT116 knockout cells.
文摘of main observation and conclusion We have achieved the total synthesis of an architecturally and biologically intriguing cyclic polypeptide,rhizonin A(1);in an exceptionally concise and convergent fashion.The strategic route entails 9 longest linear steps to elaborate commercially available materials into the natural product with an overall yield of 9.7%.The brevity of sequence and high overall yield was fueled by the judicious selection of chemical tactics.Rhizonin A(1)showed weak inhibitory effects on the cell viability of HCT116 colorectal cancer cells and this activity was dependent on hypoxia-inducible factors.
基金National Science Foundation of China(Nos.21701145 and 21701146)China Postdoctoral Science Foundation(Nos.2017M610459 and 2018T110739)。
文摘Aprotic Li-CO_(2)batteries have attracted growing interest due to their high theoretical energy density and its ability to use green house gas CO_(2)for energy storage.However,the poor ability of activating CO_(2)in organic electrolyte often leads to the premature termination of CO_(2)reduction reaction(CO_(2)RR)directly.Here in this work,cetyl trimethyl ammonium bromide(CTAB)was introduced into a dimethyl sulfoxide(DMSO)based Li-CO_(2)battery for the first time to enhance the CO_(2)RR.Significantly improved electrochemical performances,including reduced discharge over-potential and increased discharge capacity,can be achieved with the addition of CTAB.Ab initio molecular dynamics(AIMD)simulations show that quaternary ammonium group CTA^(+) can accelerate CO_(2)reduction process by forming more stable contact ion pair(CIP)with CO_(2)^(–),reducing the energy barrier for CO_(2)RR,thus improving the CO_(2)reduction process.In addition,adding CTA^(+) is also favorable for the solution-phase growth of discharge products because of the improved migration ability of stable CTA^(+)-CO_(2)^(–) CIP in the electrolyte,which is beneficial for improving the utilization ratio of cathode.This work could facilitate the development of CO_(2)RR by providing a novel understanding of CO_(2)RR mechanism in organic system.
