Background: Patients with craniocerebral trauma may suffer ischemic brain injury and neurological dysfunction due to immune inflammation and neuroendocrine reactions. Dexmedetomidine (Dex) is one of the commonly used ...Background: Patients with craniocerebral trauma may suffer ischemic brain injury and neurological dysfunction due to immune inflammation and neuroendocrine reactions. Dexmedetomidine (Dex) is one of the commonly used anesthetic drugs in clinic. Studies have shown Dex has the function of protecting brain nerves and inhibiting inflammation. However, there are few studies on the effects of different doses of dexmedetomidine on patients undergoing surgery. The purpose of this study is to observe the effects of different doses of Dex on hemodynamics and brain protection in patients undergoing brain trauma surgery. Materials and Methods: Eighty patients with craniocerebral trauma surgery were randomly divided into study group (group A, n = 40) and control group (group B, n = 40) by random number table method. Dex pump volume was 0.5 μg/kg/h in group A and 1.0 μg/kg/h in group B. Heart rate (HR) and mean arterial pressure (MAP) were recorded before anesthesia induction (T0), immediately after endotracheal intubation (T1) and at the end of operation (T2). The serum levels of central nervous system specific protein (S-100β) and neuron specific enolase (NSE) were measured and compared between the two groups at T0 and T2. Results: HR and MAP in group A were significantly higher than those in group B at T2, and the difference was statistically significant (P P β and NSE in both groups at T2 were lower than those at T0, and the concentrations of S-100β and NSE in group A were significantly lower than those in group B at T2 (P Conclusions: 0.5 μg/kg dose of Dex is stable in hemodynamics and has a better protective effect on brain function in patients with traumatic brain injury.展开更多
In this paper, we present one method to attack on the GMR-2 algorithm used in satellite phone under the chosen-plaintexts. First using the relationship of the rows of the two s-boxes and outputs of the F coordinate, w...In this paper, we present one method to attack on the GMR-2 algorithm used in satellite phone under the chosen-plaintexts. First using the relationship of the rows of the two s-boxes and outputs of the F coordinate, we attack on the GMR-2 algorithm. Then we deduce the happening probability of read-collision, and analyze its mathematical expectation. Finally, combining with the read-collision, we present an improved method to attack on the GMR-2 algorithm. The research results show that the complexity of the improved algorithm is about 220, and the session key Kc can be recovered in about 0.3 seconds. Compared with the available method, our method takes less time than the guess-and-decide attack method which is 700 s.展开更多
Two-dimensional coordination polymers(CPs) have aroused tremendous interest as electrocatalysts because the catalytic performance could be fine-tuned by their well-designed coordination layers with highly accessible a...Two-dimensional coordination polymers(CPs) have aroused tremendous interest as electrocatalysts because the catalytic performance could be fine-tuned by their well-designed coordination layers with highly accessible and active metal sites.However,it remains great challenge for CP-based catalysts to be utilized for electrocatalytic oxidation reactions due to their inefficient activities and low catalytic stabilities.Herein,we applied a mixed-metal strategy to fabricate two-dimensional Co_xNi_(1-x)-CPs with dual active sites for electrocatalytic water and urea oxidation.By metal ratio regulation in the twodimensional layer,an optimized Co_(2/3)Ni_(1/3)-CP exhibits a water oxidation performance with an overpotential of 325 mV at a current density of 10 mA cm^(-2) and a Tafel slope of 86 mV dec^(-1) in alkaline solution for oxygen evolution reaction.Importantly,a lower potential than that of commercial RuO_(2) is observed over20 mA cm^(-2).Co_(2/3)Ni_(1/3)-CP also displays a potential of 1.381 V at 10 mA cm^(-2) for urea oxidation reaction and a Tafel slope of 124 mV dec^(-1).This mixed-metal strategy to maximize synergistic effect of different metal centers may ultimately lead to promising electrocatalysts for small molecule oxidation reaction.展开更多
Confounding of three binary-variable counterfactual model with directed acyclic graph (DAG) is discussed in this paper. According to the effect between the control variable and the covariate variable, we investigate t...Confounding of three binary-variable counterfactual model with directed acyclic graph (DAG) is discussed in this paper. According to the effect between the control variable and the covariate variable, we investigate three causal counterfactual models: the control variable is independent of the covariate variable, the control variable has the effect on the covariate variable and the covariate variable affects the control variable. Using the ancillary information based on conditional independence hypotheses and ignorability, the sufficient conditions to determine whether the covariate variable is an irrelevant factor or whether there is no confounding in each counterfactual model are obtained.展开更多
Large-scale poverty alleviation is one of the three major strategic actions of Guizhou Province to plan for leapfrog development.Through building an econometric model,this paper made an empirical analysis of relations...Large-scale poverty alleviation is one of the three major strategic actions of Guizhou Province to plan for leapfrog development.Through building an econometric model,this paper made an empirical analysis of relationship between farmers'income structure and consumption in Guizhou Province in the context of large-scale poverty alleviation.The results show that the wage income and transfer income of rural residents in Guizhou Province have a significant impact on the promotion of their consumption,and the impact of income from household business operation is also significant,but the impact is relatively weak,while the contribution of farmers'property income to their consumption is insufficient.Finally,in view of the problems in the relationship between the income structure and consumption of farmers in Guizhou Province,it came up with policy recommendations including broadening the income channels,increasing farmers'income,improving the income structure,and promoting farmers'consumption.展开更多
In the field of pipeline inner wall inspection,the snake robot demonstrates significant advantages over other inspection methods.While a simple traveling wave or meandering motion will suffice for inspecting the inner...In the field of pipeline inner wall inspection,the snake robot demonstrates significant advantages over other inspection methods.While a simple traveling wave or meandering motion will suffice for inspecting the inner wall of small-diameter pipes,comprehensively and meticulously inspecting the inner wall of large-diameter pipes requires the snake robot to adopt a helical gait that closely adheres to the inner wall.Our review of existing literature indicates that most research and development on the helical gait of snake robots has focused on the outer surface of cylinders,with very few studies dedicated to developing a helical gait specifically for the inspection of the inner wall of pipes.Therefore,in this study,we propose a helical gait that is suitable for the inner wall of pipes and meets the requirements of gas pipeline engineering.The helical gait is designed using the backbone curve method.First,we create a mathematical model for a circular helix curve with constant curvature and torsion,ensuring it is applicable to a snake robot prototype in a laboratory environment.Subsequently.we calculate the joint angles required for two conical spiral curves with variable curvature and torsion,establish a new model,and define the physical significance of the specific parameters.To ensure the feasibility of the proposed gait,we conduct experiments involving meandering and traveling wave motions to verify the communication and control between the host computer and the snake robot.Building upon this foundation,we further validate the mathematical model of the complex helical motion gait through simulation experiments.Our findings provide a theoretical basis for realizing helical movement with a real snake robot.展开更多
Atmospheric reanalysis reproduces the past atmospheric conditions through assimilation of historical meteorological observations with fixed version of a numerical weather prediction(NWP)model and data assimilation(DA)...Atmospheric reanalysis reproduces the past atmospheric conditions through assimilation of historical meteorological observations with fixed version of a numerical weather prediction(NWP)model and data assimilation(DA)system.It is widely used in weather,climate,and even business-related research and applications.This paper reports the development of CMA’s first-generation global atmospheric reanalysis(RA)covering 1979–2018(CRA-40;CRA refers to CMA-RA).CRA-40 is produced by using the Global Spectral Model(GSM)/Gridpoint Statistical Interpolation(GSI)at a 6-h time interval and a TL574 spectral(34-km)resolution with the model top at 0.27 hPa.A large number of reprocessed satellite data and widely collected conventional observations were assimilated during the reanalyzing process,including the reprocessed atmospheric motion vector(AMV)products from FY-2C/D/E/G satellites,dense conventional observations(at about 120 radiosonde and 2400 synoptic stations)over China,as well as MWHS-2 and GNSS-RO observations from FY-3C.The reanalysis fitting to observations is improved over time,especially for surface pressure with root-mean-square error reduced from 1.05 hPa in 1979 to 0.8 hPa,and for upper air temperature from 1.65 K in 1979 to 1.35 K,in 2018.The patterns of global analysis increments for temperature,specific humidity,and zonal wind are consistent with the changes in the observing system.Near surface temperature from the model’s 6-h forecast reflects the global warming trend reasonably.The CRA-40 precipitation pattern matches well with those of GPCP and other reanalyses.CRA-40 also successfully captures the QBO and its vertical and temporal development,hemispherical atmospheric circulation change,and moisture transport by the East Asian summer monsoon.CRA is now operationally running in near real time as a climate data assimilation system in CMA.展开更多
Low-dimensional materials exhibit unique quantum confinement effects and morphologies as a result of their nanoscale size in one or more dimensions,making them exhibit distinctive physical properties compared to bulk ...Low-dimensional materials exhibit unique quantum confinement effects and morphologies as a result of their nanoscale size in one or more dimensions,making them exhibit distinctive physical properties compared to bulk counterparts.Among all low-dimensional materials,due to their atomic level thickness,two-dimensional materials possess extremely large shape anisotropy and consequently are speculated to have large optically anisotropic absorption.In this work,we demonstrate an optoelectronic device based on the combination of two-dimensional material and carbon dot with wide bandgap.High-efficient luminescence of carbon dot and extremely large shape anisotropy(>1500)of two-dimensional material with the wide bandgap of>4 eV cooperatively endow the optoelectronic device with multi-functions of optically anisotropic blue-light emission,visible light modulation,wavelength-dependent ultraviolet-light detection as well as blue fluorescent film assemble.This research opens new avenues for constructing multi-function-integrated optoelectronic devices via the combination of nanomaterials with different dimensions.展开更多
Sn-based materials are promising candidates for lithium storage but suffer generally from huge volume change during the(de)lithiation processes.Sn-organic materials with monodispersed Sn centers surrounded by lithium ...Sn-based materials are promising candidates for lithium storage but suffer generally from huge volume change during the(de)lithiation processes.Sn-organic materials with monodispersed Sn centers surrounded by lithium active ligands can alleviate the volume change of anode materials based on reversible(de)lithiation processes.However,the structural factors governing the kinetics of lithium storage and utilization efficiency of active sites are not well understood to date.Herein,we report three two-dimensional Sn-organic materials with enhanced lithium storage performance by manipulation ofπ-aromatic conjugation of the ligands.The increasingπ-aromatic conjugation plays a key role in promoting efficient lithium storage,and the volume expansion during the(de)lithiation reaction is suppressed in these Sn-organic materials.This work reveals that theπ-aromatic conjugation of the ligand is crucial for improving the kinetics of lithium storage and the utilization of active sites in metalorganic materials with minimised volume expansion.展开更多
Zinc-air batteries(ZABs)are promising energy storage systems because of high theoretical energy density,safety,low cost,and abundance of zinc.However,the slow multi-step reaction of oxygen and heavy reliance on noble-...Zinc-air batteries(ZABs)are promising energy storage systems because of high theoretical energy density,safety,low cost,and abundance of zinc.However,the slow multi-step reaction of oxygen and heavy reliance on noble-metal catalysts hinder the practical applications of ZABs.Therefore,feasible and advanced non-noble-metal elec-trocatalysts for air cathodes need to be identified to promote the oxygen catalytic reaction.In this review,we initially introduced the advancement of ZABs in the past two decades and provided an overview of key developments in this field.Then,we discussed the work-ing mechanism and the design of bifunctional electrocatalysts from the perspective of morphology design,crystal structure tuning,interface strategy,and atomic engineering.We also included theoretical studies,machine learning,and advanced characterization technologies to provide a comprehensive understanding of the structure-performance relationship of electrocatalysts and the reaction pathways of the oxygen redox reactions.Finally,we discussed the challenges and prospects related to designing advanced non-noble-metal bifunctional electrocatalysts for ZABs.展开更多
To date,several molecules have been found to facilitate iron influx,while the types of iron influx channels remain to be elucidated.Here,Piezo1 channel was identified as a key iron transporter in response to mechanica...To date,several molecules have been found to facilitate iron influx,while the types of iron influx channels remain to be elucidated.Here,Piezo1 channel was identified as a key iron transporter in response to mechanical stress.Piezo1-mediated iron overload disturbed iron metabolism and exaggerated ferroptosis in nucleus pulposus cells(NPCs).Importantly,Piezo1-induced iron influx was independent of the transferrin receptor(TFRC),a well-recognized iron gatekeeper.Furthermore,pharmacological inactivation of Piezo1 profoundly reduced iron accumulation,alleviated mitochondrial ROS,and suppressed ferroptotic alterations in stimulation of mechanical stress.Moreover,conditional knockout of Piezo1(Col2a1-CreERT Piezo1^(flox/flox))attenuated the mechanical injury-induced intervertebral disc degeneration(IVDD).Notably,the protective effect of Piezo1 deficiency in IVDD was dampened in Piezo1/Gpx4 conditional double knockout(cDKO)mice(Col2a1-CreERT Piezo1^(flox/flox)/Gpx4^(flox/flox)).These findings suggest that Piezo1 is a potential determinant of iron influx,indicating that the Piezo1-iron-ferroptosis axis might shed light on the treatment of mechanical stress-induced diseases.展开更多
The global energy cycle is a diagnostic metric widely used to gauge the quality of datasets. In this paper, the "Mixed Space-Time Domain" method for diagnosis of energy cycle is evaluated by using newly deve...The global energy cycle is a diagnostic metric widely used to gauge the quality of datasets. In this paper, the "Mixed Space-Time Domain" method for diagnosis of energy cycle is evaluated by using newly developed datasets-the Chinese Reanalysis Interim (CRAI) and ECMWF Reanalysis version 5 (ERA5), over a 7-yr period (2010-16) on seasonal and monthly timescales. The results show that the energy components calculated from the two reanalysis datasets are highly consistent;however, some components in the global energy integral from CRAI are slightly larger than those from ERA5. The main discrepancy in the energy components stems from the conversion of baroclinic process, whereas the dominant difference originates from the conversion from stationary eddy available potential energy to stationary eddy kinetic energy (CES), which is caused by systematic differences in the temperature and vertical velocity in low-mid latitudes of the Northern Hemisphere and near the Antarctic, where there exist complex terrains. Furthermore, the monthly analysis reveals that the general discrepancy in the temporal variation between the two datasets also lie mainly in the CES as well as corresponding generation and dissipation rates.展开更多
The Asian subtropical westerly jet(AWJ) exerts crucial influences on Eurasian continent weather and climate. This paper analyzes the advantages and limitations of CRA-40, which is China's first generation 40-yr(1...The Asian subtropical westerly jet(AWJ) exerts crucial influences on Eurasian continent weather and climate. This paper analyzes the advantages and limitations of CRA-40, which is China's first generation 40-yr(1979–2018) global atmosphere and land reanalysis product, in describing the characteristics of AWJ, compared with the ECMWF Reanalysis version 5(ERA5) and NCEP Climate Forecast System Reanalysis(CFSR). The results show a close agreement across the three reanalyses on the whole.(1) In terms of climatology, overall differences of 200-h Pa zonal wind across the three reanalyses are within ± 0.5 m s^(-1)(i.e., ± 2%). Large differences with maxima of ± 2 m s^(-1)(±5%) appear over the Iranian Plateau and south of the Tibetan Plateau in the mid–upper troposphere in winter.(2) For seasonal cycle, the position and intensity of the AWJ centers in the three reanalyses are highly consistent, with correlation coefficient over 0.98. But there are some discrepancies in the zonal shift of the western AWJ center during the transition season.(3) On the interannual timescale, intensity of all AWJ centers varies consistently among the three reanalyses, while larger differences appear in their meridional displacement, especially in the eastern AWJ center.(4)For long-term variations, the three reanalyses all present a significant northward movement of the westerly jet axis in winter, and a southward displacement over central Asia(40°–80°E) and a northward migration over East Asia(80°–110°E) in summer. Thus, this study has provided confidence that CRA-40 has comparable performance with ERA5 and CFSR in depicting the characteristics of AWJ.展开更多
China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributio...China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributions of local and remote atmospheric moisture fluxes to precipitation in East China derived from CRA-40 are compared with those derived from the ECMWF reanalysis version 5(ERA-5). Observed precipitation and evaporation data are also used for validation. As for mean precipitation, CRA-40 matches the observation better in winter and spring than in summer, with a larger wet bias(1.41 mm day^(-1)) in summer than that in ERA-5(0.97 mm day^(-1)), particularly over South China. The conservation of atmospheric water vapor over East China measured by CRA-40 is comparable to that of ERA-5. Both reanalyses show a dominant role of the remote moisture transport in the East China precipitation.In comparison, the annual precipitation induced by the moisture influx from the west of the study domain in CRA-40 is 80 mm less than that in ERA-5. The recycling ratio of annual mean precipitation in CRA-40 is approximately21.1%, slightly larger than that in ERA-5(20.1%). The maximum difference of each hydrological component between the two datasets appears in the summer horizontal moisture influx(3.57 ×10^(7) kg s^(-1);ERA-5 is larger) and winter runoff(1.84 ×10^(7) kg s^(-1);CRA-40 is larger). CRA-40 shows better performance than ERA-5 in capturing the interannual variability of precipitation over East China, as evinced by a higher correlation coefficient with the observation(0.77 versus 0.33). The trend of summer precipitation since 2011 is better reproduced in CRA-40. Both reanalyses show prominent contribution of the southern moisture influx to the interannual variation of precipitation. This study demonstrates the reliability of CRA-40 in representing the hydrological cycle over East China and provides a useful reference for future application of CRA-40 in water cycle studies.展开更多
A well-designed redox-active organic linker,pyrazine-2,3,5,6-tetracarboxylate(H_4pztc)with brimming active sites for lithium ions storage was utilized to construct coordination polymers(CPs)via a facile hydrothermal r...A well-designed redox-active organic linker,pyrazine-2,3,5,6-tetracarboxylate(H_4pztc)with brimming active sites for lithium ions storage was utilized to construct coordination polymers(CPs)via a facile hydrothermal reaction.Those two isostructural two-dimensional(2D)CPs,namely[M_2(pztc)(H_2O)_6]_n(M=Co for 1 and Ni for 2),delivered excellent reversible capacities and stable cycling performance as anodes in lithium ion batteries.As demonstrated in electrochemical studies,1 and 2 can achieve highly reversible capacities of 815 and 536 mA h g^(-1)at 200 mA g^(-1)for 150 cycles,respectively,best performed for the reported2D-CP-based anode materials.The electrochemical mechanism studies showed that the remarkable performances can be ascribed to the synergistic Li-storage redox reactions of metal centers and organic moieties.Our work highlights the opportunities of using a well-designed organic ligand to construct low-dimensional CPs as new type of electrode materials for advanced lithium ion batteries.展开更多
Nowadays,multi-shelled mesoporous hollow metal oxide nanospheres have drawn a lot of attention due to their large internal space,nanometer scaled shell thickness,high specific surface area and well-defined mesopores,o...Nowadays,multi-shelled mesoporous hollow metal oxide nanospheres have drawn a lot of attention due to their large internal space,nanometer scaled shell thickness,high specific surface area and well-defined mesopores,of which unique nanostructure endows metallic oxides with enhanced properties.In this thesis,we have studied and proposed a versatile ligand-assisted cooperative template method to synthesize multi-shelled mesoporous hollow metal hydroxides and oxides nanospheres,in which silica nanospheres act as sacrificial templates and the coordination interaction between metal ions and surfactant can be cooperatively amplified by using chelating ligand(ascorbic acid)as a co-template.The synthesized metal hydroxides and oxides nanospheres possess stable hollow structure,uniform spherical morphology and tunable diameter from 270 to 690 nm.All the multi-shelled mesoporous hollow metal hydroxide and metal oxide nanospheres exhibit high surface areas(up to 640 m^(2)/g).The obtained Au nanoparticles loaded composited nanospheres exhibit excellent reactivity for solvent-free aerobic oxidation of ethylbenzene with high activity(28.2%)and selectivity(87%).展开更多
UltrasmaU Au10 clusters have a unique electronic structure and can act as a charge reservoir to donate electrons or accept charges. This is particularly important for catalysis, since it leads to facile charge transfe...UltrasmaU Au10 clusters have a unique electronic structure and can act as a charge reservoir to donate electrons or accept charges. This is particularly important for catalysis, since it leads to facile charge transfer across the interface between the gold species and the oxide substrate. To determine the electronic and structural effects of Au10 on the catalytic oxidation, a TiO2 charge carrier was chosen as the substrate to anchor Au10 for olefin oxidation. Au10 supported on TiO2-RP (RP = pyramid-capped columnar structure) exhibited superior catalytic activity to Au10/TiO2 nanotubes and Au10/P25. In addition, the supported Au10 clusters gave rise to higher activity than supported Au20, Au144 clusters, and 5 nm Au nanocrystals. The superior catalytic ability of Au^0fFiO2-RP arises from the charge/discharge effect of the Au10/TiO2-RP interface, which effectively improves the formation of active oxygen species on electron-rich gold atoms at the terminal position of Au10, and promotes the activation of olefin C--C bonds on the electron-deficient gold atoms of Au10.展开更多
Visual analytics techniques are widely utilized to facilitate the exploration of online educational data.To help researchers better understand the necessity and the efficiency of these techniques in online education,w...Visual analytics techniques are widely utilized to facilitate the exploration of online educational data.To help researchers better understand the necessity and the efficiency of these techniques in online education,we systematically review related works of the past decade to provide a comprehensive view of the use of visualization in online education problems.We establish a taxonomy based on the analysis goal and classify the existing visual analytics techniques into four categories:learning behavior analysis,learning content analysis,analysis of interactions among students,and prediction and recommendation.The use of visual analytics techniques is summarized in each category to show their benefits in different analysis tasks.At last,we discuss the future research opportunities and challenges in the utilization of visual analytics techniques for online education.展开更多
文摘Background: Patients with craniocerebral trauma may suffer ischemic brain injury and neurological dysfunction due to immune inflammation and neuroendocrine reactions. Dexmedetomidine (Dex) is one of the commonly used anesthetic drugs in clinic. Studies have shown Dex has the function of protecting brain nerves and inhibiting inflammation. However, there are few studies on the effects of different doses of dexmedetomidine on patients undergoing surgery. The purpose of this study is to observe the effects of different doses of Dex on hemodynamics and brain protection in patients undergoing brain trauma surgery. Materials and Methods: Eighty patients with craniocerebral trauma surgery were randomly divided into study group (group A, n = 40) and control group (group B, n = 40) by random number table method. Dex pump volume was 0.5 μg/kg/h in group A and 1.0 μg/kg/h in group B. Heart rate (HR) and mean arterial pressure (MAP) were recorded before anesthesia induction (T0), immediately after endotracheal intubation (T1) and at the end of operation (T2). The serum levels of central nervous system specific protein (S-100β) and neuron specific enolase (NSE) were measured and compared between the two groups at T0 and T2. Results: HR and MAP in group A were significantly higher than those in group B at T2, and the difference was statistically significant (P P β and NSE in both groups at T2 were lower than those at T0, and the concentrations of S-100β and NSE in group A were significantly lower than those in group B at T2 (P Conclusions: 0.5 μg/kg dose of Dex is stable in hemodynamics and has a better protective effect on brain function in patients with traumatic brain injury.
基金supported by China Scholarship Council under Grant No.201506965088
文摘In this paper, we present one method to attack on the GMR-2 algorithm used in satellite phone under the chosen-plaintexts. First using the relationship of the rows of the two s-boxes and outputs of the F coordinate, we attack on the GMR-2 algorithm. Then we deduce the happening probability of read-collision, and analyze its mathematical expectation. Finally, combining with the read-collision, we present an improved method to attack on the GMR-2 algorithm. The research results show that the complexity of the improved algorithm is about 220, and the session key Kc can be recovered in about 0.3 seconds. Compared with the available method, our method takes less time than the guess-and-decide attack method which is 700 s.
基金supported by the National Natural Science Foundation of China (Grant number 21622105 and 21931004)the Natural Science Foundation of Tianjin (Grant number 18JCJQJC47200)+2 种基金the Fundamental Research Funds for the Central UniversitiesNankai University (63201016 and 63201043)the Ministry of Education of China (Grant number B12015)。
文摘Two-dimensional coordination polymers(CPs) have aroused tremendous interest as electrocatalysts because the catalytic performance could be fine-tuned by their well-designed coordination layers with highly accessible and active metal sites.However,it remains great challenge for CP-based catalysts to be utilized for electrocatalytic oxidation reactions due to their inefficient activities and low catalytic stabilities.Herein,we applied a mixed-metal strategy to fabricate two-dimensional Co_xNi_(1-x)-CPs with dual active sites for electrocatalytic water and urea oxidation.By metal ratio regulation in the twodimensional layer,an optimized Co_(2/3)Ni_(1/3)-CP exhibits a water oxidation performance with an overpotential of 325 mV at a current density of 10 mA cm^(-2) and a Tafel slope of 86 mV dec^(-1) in alkaline solution for oxygen evolution reaction.Importantly,a lower potential than that of commercial RuO_(2) is observed over20 mA cm^(-2).Co_(2/3)Ni_(1/3)-CP also displays a potential of 1.381 V at 10 mA cm^(-2) for urea oxidation reaction and a Tafel slope of 124 mV dec^(-1).This mixed-metal strategy to maximize synergistic effect of different metal centers may ultimately lead to promising electrocatalysts for small molecule oxidation reaction.
文摘Confounding of three binary-variable counterfactual model with directed acyclic graph (DAG) is discussed in this paper. According to the effect between the control variable and the covariate variable, we investigate three causal counterfactual models: the control variable is independent of the covariate variable, the control variable has the effect on the covariate variable and the covariate variable affects the control variable. Using the ancillary information based on conditional independence hypotheses and ignorability, the sufficient conditions to determine whether the covariate variable is an irrelevant factor or whether there is no confounding in each counterfactual model are obtained.
基金Project of National Social Science Foundation(19BJL081)Humanity and Social Science Project of Colleges and Universities of Guizhou Provincial Department of Education(2018gh04).
文摘Large-scale poverty alleviation is one of the three major strategic actions of Guizhou Province to plan for leapfrog development.Through building an econometric model,this paper made an empirical analysis of relationship between farmers'income structure and consumption in Guizhou Province in the context of large-scale poverty alleviation.The results show that the wage income and transfer income of rural residents in Guizhou Province have a significant impact on the promotion of their consumption,and the impact of income from household business operation is also significant,but the impact is relatively weak,while the contribution of farmers'property income to their consumption is insufficient.Finally,in view of the problems in the relationship between the income structure and consumption of farmers in Guizhou Province,it came up with policy recommendations including broadening the income channels,increasing farmers'income,improving the income structure,and promoting farmers'consumption.
基金supported by the BUCEA Post Graduate Innovation Project,China(PG2023096).
文摘In the field of pipeline inner wall inspection,the snake robot demonstrates significant advantages over other inspection methods.While a simple traveling wave or meandering motion will suffice for inspecting the inner wall of small-diameter pipes,comprehensively and meticulously inspecting the inner wall of large-diameter pipes requires the snake robot to adopt a helical gait that closely adheres to the inner wall.Our review of existing literature indicates that most research and development on the helical gait of snake robots has focused on the outer surface of cylinders,with very few studies dedicated to developing a helical gait specifically for the inspection of the inner wall of pipes.Therefore,in this study,we propose a helical gait that is suitable for the inner wall of pipes and meets the requirements of gas pipeline engineering.The helical gait is designed using the backbone curve method.First,we create a mathematical model for a circular helix curve with constant curvature and torsion,ensuring it is applicable to a snake robot prototype in a laboratory environment.Subsequently.we calculate the joint angles required for two conical spiral curves with variable curvature and torsion,establish a new model,and define the physical significance of the specific parameters.To ensure the feasibility of the proposed gait,we conduct experiments involving meandering and traveling wave motions to verify the communication and control between the host computer and the snake robot.Building upon this foundation,we further validate the mathematical model of the complex helical motion gait through simulation experiments.Our findings provide a theoretical basis for realizing helical movement with a real snake robot.
基金Supported by the China Meteorological Administration Special Public Welfare Research Fund(GYHY201506002)National Innovation Project for Meteorological Science and Technology(CMAGGTD003-5).
文摘Atmospheric reanalysis reproduces the past atmospheric conditions through assimilation of historical meteorological observations with fixed version of a numerical weather prediction(NWP)model and data assimilation(DA)system.It is widely used in weather,climate,and even business-related research and applications.This paper reports the development of CMA’s first-generation global atmospheric reanalysis(RA)covering 1979–2018(CRA-40;CRA refers to CMA-RA).CRA-40 is produced by using the Global Spectral Model(GSM)/Gridpoint Statistical Interpolation(GSI)at a 6-h time interval and a TL574 spectral(34-km)resolution with the model top at 0.27 hPa.A large number of reprocessed satellite data and widely collected conventional observations were assimilated during the reanalyzing process,including the reprocessed atmospheric motion vector(AMV)products from FY-2C/D/E/G satellites,dense conventional observations(at about 120 radiosonde and 2400 synoptic stations)over China,as well as MWHS-2 and GNSS-RO observations from FY-3C.The reanalysis fitting to observations is improved over time,especially for surface pressure with root-mean-square error reduced from 1.05 hPa in 1979 to 0.8 hPa,and for upper air temperature from 1.65 K in 1979 to 1.35 K,in 2018.The patterns of global analysis increments for temperature,specific humidity,and zonal wind are consistent with the changes in the observing system.Near surface temperature from the model’s 6-h forecast reflects the global warming trend reasonably.The CRA-40 precipitation pattern matches well with those of GPCP and other reanalyses.CRA-40 also successfully captures the QBO and its vertical and temporal development,hemispherical atmospheric circulation change,and moisture transport by the East Asian summer monsoon.CRA is now operationally running in near real time as a climate data assimilation system in CMA.
基金supported by the National Natural Science Foundation of China(Grants 52273311 and T2293693)the Guangdong Innovative and Entrepreneurial Research Team Program(No.2017ZT07C341)+1 种基金the Shenzhen Basic Research Project(Grants JCYJ20220818100806014 and JCYJ20190809180605522)the Science and Technology Planning Project of Guangdong Province(Grants 2022A0505050066).
文摘Low-dimensional materials exhibit unique quantum confinement effects and morphologies as a result of their nanoscale size in one or more dimensions,making them exhibit distinctive physical properties compared to bulk counterparts.Among all low-dimensional materials,due to their atomic level thickness,two-dimensional materials possess extremely large shape anisotropy and consequently are speculated to have large optically anisotropic absorption.In this work,we demonstrate an optoelectronic device based on the combination of two-dimensional material and carbon dot with wide bandgap.High-efficient luminescence of carbon dot and extremely large shape anisotropy(>1500)of two-dimensional material with the wide bandgap of>4 eV cooperatively endow the optoelectronic device with multi-functions of optically anisotropic blue-light emission,visible light modulation,wavelength-dependent ultraviolet-light detection as well as blue fluorescent film assemble.This research opens new avenues for constructing multi-function-integrated optoelectronic devices via the combination of nanomaterials with different dimensions.
基金This research was funded by the National Natural Science Foundation of China(grant refs:21622105 and 21931004)the Natural Science Foundation of Tianjin(grant ref:18JCJQJC47200)the Ministry of Education of China(grant ref:B12015).
文摘Sn-based materials are promising candidates for lithium storage but suffer generally from huge volume change during the(de)lithiation processes.Sn-organic materials with monodispersed Sn centers surrounded by lithium active ligands can alleviate the volume change of anode materials based on reversible(de)lithiation processes.However,the structural factors governing the kinetics of lithium storage and utilization efficiency of active sites are not well understood to date.Herein,we report three two-dimensional Sn-organic materials with enhanced lithium storage performance by manipulation ofπ-aromatic conjugation of the ligands.The increasingπ-aromatic conjugation plays a key role in promoting efficient lithium storage,and the volume expansion during the(de)lithiation reaction is suppressed in these Sn-organic materials.This work reveals that theπ-aromatic conjugation of the ligand is crucial for improving the kinetics of lithium storage and the utilization of active sites in metalorganic materials with minimised volume expansion.
基金the Natural Science Foundation of China(Grant No:22309180)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No:XDB0600000,XDB0600400)+3 种基金Liaoning Binhai Laboratory,(Grant No:LILBLB-2023-04)Dalian Revitalization Talents Program(Grant No:2022RG01)Youth Science and Technology Foundation of Dalian(Grant No:2023RQ015)the University of Waterloo.
文摘Zinc-air batteries(ZABs)are promising energy storage systems because of high theoretical energy density,safety,low cost,and abundance of zinc.However,the slow multi-step reaction of oxygen and heavy reliance on noble-metal catalysts hinder the practical applications of ZABs.Therefore,feasible and advanced non-noble-metal elec-trocatalysts for air cathodes need to be identified to promote the oxygen catalytic reaction.In this review,we initially introduced the advancement of ZABs in the past two decades and provided an overview of key developments in this field.Then,we discussed the work-ing mechanism and the design of bifunctional electrocatalysts from the perspective of morphology design,crystal structure tuning,interface strategy,and atomic engineering.We also included theoretical studies,machine learning,and advanced characterization technologies to provide a comprehensive understanding of the structure-performance relationship of electrocatalysts and the reaction pathways of the oxygen redox reactions.Finally,we discussed the challenges and prospects related to designing advanced non-noble-metal bifunctional electrocatalysts for ZABs.
基金supported in part by the National Nature Science Foundation(81874022 and 82172483 to Xinyu Liu,82102522 to Lianlei Wang,82072478 to Yunpeng Zhao,82072435 to Qiang Yang,82073437 to Weiwei Li,81930070 to Shiqing Feng,82272548 to Lei Cheng)Key R&D Project of Shandong Province(2022CXGC010503 to Xinyu Liu)+1 种基金Shandong Natural Science Foundation(ZR202102210113 to Lianlei Wang,ZR2020YQ54 to Yunpeng Zhao)Shandong Province Taishan Scholar Project(tsqn202211317 to Lianlei Wang).The authors thank the Translational Medicine Core Facility of Shandong University for the consultation and instrument availability that supported this work.
文摘To date,several molecules have been found to facilitate iron influx,while the types of iron influx channels remain to be elucidated.Here,Piezo1 channel was identified as a key iron transporter in response to mechanical stress.Piezo1-mediated iron overload disturbed iron metabolism and exaggerated ferroptosis in nucleus pulposus cells(NPCs).Importantly,Piezo1-induced iron influx was independent of the transferrin receptor(TFRC),a well-recognized iron gatekeeper.Furthermore,pharmacological inactivation of Piezo1 profoundly reduced iron accumulation,alleviated mitochondrial ROS,and suppressed ferroptotic alterations in stimulation of mechanical stress.Moreover,conditional knockout of Piezo1(Col2a1-CreERT Piezo1^(flox/flox))attenuated the mechanical injury-induced intervertebral disc degeneration(IVDD).Notably,the protective effect of Piezo1 deficiency in IVDD was dampened in Piezo1/Gpx4 conditional double knockout(cDKO)mice(Col2a1-CreERT Piezo1^(flox/flox)/Gpx4^(flox/flox)).These findings suggest that Piezo1 is a potential determinant of iron influx,indicating that the Piezo1-iron-ferroptosis axis might shed light on the treatment of mechanical stress-induced diseases.
基金Supported by the China Meteorological Administration(CMA)Special Public Welfare Research Fund(GYHY201506002)National Key Research and Development Program of China(2017YFA0604500)+1 种基金CMA Special Project for Developing Key Techniques for Operational Meteorological Forecast(YBGJXM201706)National Natural Science Foundation of China(41305091)
文摘The global energy cycle is a diagnostic metric widely used to gauge the quality of datasets. In this paper, the "Mixed Space-Time Domain" method for diagnosis of energy cycle is evaluated by using newly developed datasets-the Chinese Reanalysis Interim (CRAI) and ECMWF Reanalysis version 5 (ERA5), over a 7-yr period (2010-16) on seasonal and monthly timescales. The results show that the energy components calculated from the two reanalysis datasets are highly consistent;however, some components in the global energy integral from CRAI are slightly larger than those from ERA5. The main discrepancy in the energy components stems from the conversion of baroclinic process, whereas the dominant difference originates from the conversion from stationary eddy available potential energy to stationary eddy kinetic energy (CES), which is caused by systematic differences in the temperature and vertical velocity in low-mid latitudes of the Northern Hemisphere and near the Antarctic, where there exist complex terrains. Furthermore, the monthly analysis reveals that the general discrepancy in the temporal variation between the two datasets also lie mainly in the CES as well as corresponding generation and dissipation rates.
基金Supported by the Program of International S&T Cooperation of Chinese Academy of Sciences (2018YFE0196000)National Natural Science Foundation of China (41675076)。
文摘The Asian subtropical westerly jet(AWJ) exerts crucial influences on Eurasian continent weather and climate. This paper analyzes the advantages and limitations of CRA-40, which is China's first generation 40-yr(1979–2018) global atmosphere and land reanalysis product, in describing the characteristics of AWJ, compared with the ECMWF Reanalysis version 5(ERA5) and NCEP Climate Forecast System Reanalysis(CFSR). The results show a close agreement across the three reanalyses on the whole.(1) In terms of climatology, overall differences of 200-h Pa zonal wind across the three reanalyses are within ± 0.5 m s^(-1)(i.e., ± 2%). Large differences with maxima of ± 2 m s^(-1)(±5%) appear over the Iranian Plateau and south of the Tibetan Plateau in the mid–upper troposphere in winter.(2) For seasonal cycle, the position and intensity of the AWJ centers in the three reanalyses are highly consistent, with correlation coefficient over 0.98. But there are some discrepancies in the zonal shift of the western AWJ center during the transition season.(3) On the interannual timescale, intensity of all AWJ centers varies consistently among the three reanalyses, while larger differences appear in their meridional displacement, especially in the eastern AWJ center.(4)For long-term variations, the three reanalyses all present a significant northward movement of the westerly jet axis in winter, and a southward displacement over central Asia(40°–80°E) and a northward migration over East Asia(80°–110°E) in summer. Thus, this study has provided confidence that CRA-40 has comparable performance with ERA5 and CFSR in depicting the characteristics of AWJ.
基金Supported by the National Natural Science Foundation of China (41675076)Program of International S&T Cooperation of Chinese Academy of Sciences (2018YFE0196000)Innovative Team Project of Lanzhou Institute of Arid Meteorology (GHSCXTD-2020-2)。
文摘China Meteorological Administration(CMA) recently released its 40-yr(1979–2018) global Chinese reanalysis(CRA-40) dataset. To assess performance of the CRA-40 data in quantifying the regional water cycle, contributions of local and remote atmospheric moisture fluxes to precipitation in East China derived from CRA-40 are compared with those derived from the ECMWF reanalysis version 5(ERA-5). Observed precipitation and evaporation data are also used for validation. As for mean precipitation, CRA-40 matches the observation better in winter and spring than in summer, with a larger wet bias(1.41 mm day^(-1)) in summer than that in ERA-5(0.97 mm day^(-1)), particularly over South China. The conservation of atmospheric water vapor over East China measured by CRA-40 is comparable to that of ERA-5. Both reanalyses show a dominant role of the remote moisture transport in the East China precipitation.In comparison, the annual precipitation induced by the moisture influx from the west of the study domain in CRA-40 is 80 mm less than that in ERA-5. The recycling ratio of annual mean precipitation in CRA-40 is approximately21.1%, slightly larger than that in ERA-5(20.1%). The maximum difference of each hydrological component between the two datasets appears in the summer horizontal moisture influx(3.57 ×10^(7) kg s^(-1);ERA-5 is larger) and winter runoff(1.84 ×10^(7) kg s^(-1);CRA-40 is larger). CRA-40 shows better performance than ERA-5 in capturing the interannual variability of precipitation over East China, as evinced by a higher correlation coefficient with the observation(0.77 versus 0.33). The trend of summer precipitation since 2011 is better reproduced in CRA-40. Both reanalyses show prominent contribution of the southern moisture influx to the interannual variation of precipitation. This study demonstrates the reliability of CRA-40 in representing the hydrological cycle over East China and provides a useful reference for future application of CRA-40 in water cycle studies.
基金supported by the National Natural Science Foundation of China(21622105,21501071,21421001)Shenzhen Fundamental Research Project(JCYJ20160525164227350)+1 种基金the Ministry of Education of China(B12015)the Natural Science Foundation of Tianjin(18JCJQJC47200)
文摘A well-designed redox-active organic linker,pyrazine-2,3,5,6-tetracarboxylate(H_4pztc)with brimming active sites for lithium ions storage was utilized to construct coordination polymers(CPs)via a facile hydrothermal reaction.Those two isostructural two-dimensional(2D)CPs,namely[M_2(pztc)(H_2O)_6]_n(M=Co for 1 and Ni for 2),delivered excellent reversible capacities and stable cycling performance as anodes in lithium ion batteries.As demonstrated in electrochemical studies,1 and 2 can achieve highly reversible capacities of 815 and 536 mA h g^(-1)at 200 mA g^(-1)for 150 cycles,respectively,best performed for the reported2D-CP-based anode materials.The electrochemical mechanism studies showed that the remarkable performances can be ascribed to the synergistic Li-storage redox reactions of metal centers and organic moieties.Our work highlights the opportunities of using a well-designed organic ligand to construct low-dimensional CPs as new type of electrode materials for advanced lithium ion batteries.
基金supported by the National Natural Science Foundation of China(Nos.21671073 and 21621001)the“111”Project of the Ministry of Education of China(No.B17020)Program for JLU Science and Technology Innovative Research Team。
文摘Nowadays,multi-shelled mesoporous hollow metal oxide nanospheres have drawn a lot of attention due to their large internal space,nanometer scaled shell thickness,high specific surface area and well-defined mesopores,of which unique nanostructure endows metallic oxides with enhanced properties.In this thesis,we have studied and proposed a versatile ligand-assisted cooperative template method to synthesize multi-shelled mesoporous hollow metal hydroxides and oxides nanospheres,in which silica nanospheres act as sacrificial templates and the coordination interaction between metal ions and surfactant can be cooperatively amplified by using chelating ligand(ascorbic acid)as a co-template.The synthesized metal hydroxides and oxides nanospheres possess stable hollow structure,uniform spherical morphology and tunable diameter from 270 to 690 nm.All the multi-shelled mesoporous hollow metal hydroxide and metal oxide nanospheres exhibit high surface areas(up to 640 m^(2)/g).The obtained Au nanoparticles loaded composited nanospheres exhibit excellent reactivity for solvent-free aerobic oxidation of ethylbenzene with high activity(28.2%)and selectivity(87%).
基金We are grateful for financial support by the National Natural Science Foundation of China (No. 21273151), and Hundred Talent Program of Chinese Academy of Sciences. Y. Z. acknowledges support by Ministry of Education for returned overseas Chinese scholars.
文摘UltrasmaU Au10 clusters have a unique electronic structure and can act as a charge reservoir to donate electrons or accept charges. This is particularly important for catalysis, since it leads to facile charge transfer across the interface between the gold species and the oxide substrate. To determine the electronic and structural effects of Au10 on the catalytic oxidation, a TiO2 charge carrier was chosen as the substrate to anchor Au10 for olefin oxidation. Au10 supported on TiO2-RP (RP = pyramid-capped columnar structure) exhibited superior catalytic activity to Au10/TiO2 nanotubes and Au10/P25. In addition, the supported Au10 clusters gave rise to higher activity than supported Au20, Au144 clusters, and 5 nm Au nanocrystals. The superior catalytic ability of Au^0fFiO2-RP arises from the charge/discharge effect of the Au10/TiO2-RP interface, which effectively improves the formation of active oxygen species on electron-rich gold atoms at the terminal position of Au10, and promotes the activation of olefin C--C bonds on the electron-deficient gold atoms of Au10.
基金supported by the grant from the National Natural Science Foundation of China(No.62177047)The first batch of new liberal arts research and reform practice projects of the Ministry of Education,China(Teaching Hall Letter[2021]No.31)+2 种基金research Project of Teaching Reform in Colleges and Universities in Hunan Province,China(Xiangjiaotong[2020]No.232)Hunan graduate education teaching reform research project,China(2020JGZD010)Central South University Graduate Education Teaching Reform Research Project,China(2020JGA007).
文摘Visual analytics techniques are widely utilized to facilitate the exploration of online educational data.To help researchers better understand the necessity and the efficiency of these techniques in online education,we systematically review related works of the past decade to provide a comprehensive view of the use of visualization in online education problems.We establish a taxonomy based on the analysis goal and classify the existing visual analytics techniques into four categories:learning behavior analysis,learning content analysis,analysis of interactions among students,and prediction and recommendation.The use of visual analytics techniques is summarized in each category to show their benefits in different analysis tasks.At last,we discuss the future research opportunities and challenges in the utilization of visual analytics techniques for online education.