This paper introduces an advanced and efficient method for distributed drone-based fruit recognition and localization, tailored to satisfy the precision and security requirements of autonomous agricultural operations....This paper introduces an advanced and efficient method for distributed drone-based fruit recognition and localization, tailored to satisfy the precision and security requirements of autonomous agricultural operations. Our method incorporates depth information to ensure precise localization and utilizes a streamlined detection network centered on the RepVGG module. This module replaces the traditional C2f module, enhancing detection performance while maintaining speed. To bolster the detection of small, distant fruits in complex settings, we integrate Selective Kernel Attention (SKAttention) and a specialized small-target detection layer. This adaptation allows the system to manage difficult conditions, such as variable lighting and obstructive foliage. To reinforce security, the tasks of recognition and localization are distributed among multiple drones, enhancing resilience against tampering and data manipulation. This distribution also optimizes resource allocation through collaborative processing. The model remains lightweight and is optimized for rapid and accurate detection, which is essential for real-time applications. Our proposed system, validated with a D435 depth camera, achieves a mean Average Precision (mAP) of 0.943 and a frame rate of 169 FPS, which represents a significant improvement over the baseline by 0.039 percentage points and 25 FPS, respectively. Additionally, the average localization error is reduced to 0.82 cm, highlighting the model’s high precision. These enhancements render our system highly effective for secure, autonomous fruit-picking operations, effectively addressing significant performance and cybersecurity challenges in agriculture. This approach establishes a foundation for reliable, efficient, and secure distributed fruit-picking applications, facilitating the advancement of autonomous systems in contemporary agricultural practices.展开更多
Background: Recent obstetrical practice tends to avoid the use of manual uterine fundal pressure (MUFP);however, data showed that MUFP is actually employed. We here attempted 1) to determine the obstetricians’ attitu...Background: Recent obstetrical practice tends to avoid the use of manual uterine fundal pressure (MUFP);however, data showed that MUFP is actually employed. We here attempted 1) to determine the obstetricians’ attitudes towards MUFP via questionnaire, and 2) to examine whether MUFP shortens the 2nd stage of labor, with the latter tested as a pilot study. Methods: A questionnaire-based study was carried out (n = 122) at meetings of Obstetrics on May 5, 2017. Then, we conducted a pilot case-control study from August 23 to September 6, 2020. Participants (n = 29) were divided into two groups;women who did and did not want MUFP;i.e., MUFP (n = 14) vs. (Non-MUFP) group (n = 15). Results: Of 122 doctors, 99.18% (121/122) used MUFP at cesarean section. 95.90% (117/122) of institutions used MUFP in spontaneous delivery. 95.08% (116/122) obstetricians considered MUFP effective and helpful. 85.24% (104/122) considered that MUFP should be employed after station +3. In the case control study, MUFP vs. Non-MUFP group showed the second-stage-duration of 58.5 (50.25 - 71.25) vs. 48 (39 - 59) minutes, without statistical significance (P = 0.101). However, importantly, MUFP, compared with Non-MUFP group, showed a significantly shorter duration from head visible on introitus (apparition) to delivery;i.e., 21.26 ± 7.32 vs. 30.13 ± 10.61 minutes (P = 0.014). Conclusions: MUFP is still used widely and MUFP shortened the duration of head apparition to delivery time. Larger-sample studies are needed to confirm the efficacy and safety of MUFP.展开更多
Gestational diabetes mellitus(GDM)is a disease of glucose intolerance that first occurs during pregnancy.Accumulating evidence underlined a link between gut microbiota dysbiosis and GDM,and microbial metabolites repre...Gestational diabetes mellitus(GDM)is a disease of glucose intolerance that first occurs during pregnancy.Accumulating evidence underlined a link between gut microbiota dysbiosis and GDM,and microbial metabolites represent a unique way to explore microbiota-host interactions.However,the associations between changes in the gut microbiota and microbial metabolites and immune homeostasis in the GDM pathogenesis remain largely unclear.In this prospective study,the characteristics of gut microbiota in both first trimester(T1)and second trimester(T2)were investigated in 46 GDM patients and 44 matched controls.We comprehensively profiled the microbial metabolites using non-targeted metabolomics and quantitatively targeted metabolomics,measurements of inflammatory cytokines and biomarkers of intestinal barrier function,and combined with correlation analysis in T2.Gut microbiota dybiosis was observed in GDM patients in both T1 and T2,and was characterised by the enrichment of multiple potentially harmful bacteria,such as UBA1819 and Erysipelatoclostridium.Besides,alterations in the microbiota were accompanied by a disturbance in tryptophan metabolism,mainly manifested as a shift towards the production of more kynurenine and less indole derivatives.Most importantly,correlation network analysis indicated that overgrowth of potential pathogens and tryptophan metabolism disorder were associated with inflammatory imbalance and disrupted epithelial barrier in GDM patients.These findings provide a greater understanding of the pathogenesis and new targets for microecological interventions by mediating tryptophan metabolism in GDM.展开更多
The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial ro...The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial role in unraveling the complexities of urban air pollution,atmospheric processes,and climate change in Beijing,China.This review paper provides a comprehensive overview of the measurements on the tower over the past two decades.Through long-term comprehensive observations,researchers have elucidated the intricate relationships between anthropogenic emissions,meteorological dynamics,and atmospheric composition,shedding light on the drivers of air pollution and its impacts on public health.The vertical measurements on the tower also enable detailed investigations into boundary layer dynamics,turbulent mixing,and pollutant dispersion,providing invaluable data for validating chemical transport models.Key findings from the tower’s research include the identification of positive feedback mechanisms between aerosols and the boundary layer,the characterization of pollutant sources and transport pathways,the determination of fluxes of gaseous and particulate species,and the assessment of the effectiveness of pollution control measures.Additionally,isotopic measurements have provided new insights into the sources and formation processes of particulate matter and reactive nitrogen species.Finally,the paper outlines future directions for tower-based research,emphasizing the need for long-term comprehensive measurements,the development of innovative tower platforms,and integration of emerging technologies.展开更多
Cerebral edema is characterized by fluid accumulation,and the glymphatic system(GS)plays a pivotal role in regulating fluid transport.Using the Tenecteplase system,magnesium salt of salvianolic acid B/ginsenoside Rg1(...Cerebral edema is characterized by fluid accumulation,and the glymphatic system(GS)plays a pivotal role in regulating fluid transport.Using the Tenecteplase system,magnesium salt of salvianolic acid B/ginsenoside Rg1(SalB/Rg1)was injected intravenously into mice 4.5 h after middle cerebral artery occlusion and once every 24 h for the following 72 h.GS function was assessed by Evans blue imaging,near-infrared fluorescence region II(NIR-II)imaging,and magnetic resonance imaging(MRI).SalB/Rg1 had significant effects on reducing the infarct volume and hemorrhagic transformation score,improving neurobehavioral function,and protecting tissue structure,especially inhibiting cerebral edema.Meanwhile,the influx/efflux drainage of GS was enhanced by SalB/Rg1 according to NIR-II imaging and MRI.SalB/Rg1 inhibited matrix metalloproteinase-9(MMP-9)activity,reduced cleavedβ-dystroglycan(β-DG),and stabilized aquaporin-4(AQP4)polarity,which was verified by colocalization with CD31.Our findings indicated that SalB/Rg1 treatment enhances GS function and attenuates cerebral edema,accompanying the regulation of the MMP9/β-DG/AQP4 pathway.展开更多
Determining accurate pulsar timing model parameters is essential for establishing TT(PT),a realization of Terrestrial Time(TT)based on a pulsar timescale(PT).This study discusses the impact of different data spans on ...Determining accurate pulsar timing model parameters is essential for establishing TT(PT),a realization of Terrestrial Time(TT)based on a pulsar timescale(PT).This study discusses the impact of different data spans on the accuracy of pulsar timing model parameters when determining pulsar timing model parameters.Using observations of PSR J0437-4715,J1909-3744,J1713+0747,and J1744-1134 from the second data release of the International Pulsar Timing Array(IPTA II,Version A),we compare the accuracy of the timing model parameters determined by these observations with different data spans.The results show for PSR J0437-4715,J1713+0747,and J1909-3744,the amplitude fluctuations of rotational frequency remain within 10^(−15),10^(−14),and 10^(−14) Hz,respectively,when the data spans for determining pulsar timing model parameters exceed 13,14,and 6 yr.Additionally,the one-year accuracy of TT(PT)is crucial for its application in timekeeping.By comparing the frequency deviations of TT(PT)relative to TT(BIPM)under both ideal(k_(r))and actual(k_(p))conditions across different data spans,we find that when the data span reaches the duration above,the accuracy of TT(PT)surpasses that of TT(TAI)under ideal conditions,slightly inferior under actual conditions.This suggests with improved observational technologies,the accuracy of TT(PT)can be further enhanced.展开更多
Objective Exposure to polycyclic aromatic hydrocarbons(PAHs)or metal(loid)s individually has been associated with neural tube defects(NTDs).However,the impacts of PAH and metal(loid)co-exposure and potential interacti...Objective Exposure to polycyclic aromatic hydrocarbons(PAHs)or metal(loid)s individually has been associated with neural tube defects(NTDs).However,the impacts of PAH and metal(loid)co-exposure and potential interaction effects on NTD risk remain unclear.We conducted a case-control study in China among population with a high prevalence of NTDs to investigate the combined effects of PAH and metal(loid)exposures on the risk of NTD.Methods Cases included 80 women who gave birth to offspring with NTDs,whereas controls were 50 women who delivered infants with no congenital malformations.We analyzed the levels of placental PAHs using gas chromatography and mass spectrometry,PAH-DNA adducts with 32P-post-labeling method,and metal(loid)s with an inductively coupled plasma mass spectrometer.Unconditional logistic regression was employed to estimate the associations between individual exposures and NTDs.Least absolute shrinkage and selection operator(LASSO)penalized regression models were used to select a subset of exposures,while additive interaction models were used to identify interaction effects.Results In the single-exposure models,we found that eight PAHs,PAH-DNA adducts,and 28 metal(loid)s were associated with NTDs.Pyrene,selenium,molybdenum,cadmium,uranium,and rubidium were selected through LASSO regression and were statistically associated with NTDs in the multiple-exposure models.Women with high levels of pyrene and molybdenum or pyrene and selenium exhibited significantly increased risk of having offspring with NTDs,indicating that these combinations may have synergistic effects on the risk of NTDs.Conclusion Our findings suggest that individual PAHs and metal(loid)s,as well as their interactions,may be associated with the risk of NTDs,which warrants further investigation.展开更多
Metal-organic frameworks(MOFs)are porous materials formed by the coordination of organic and inorganic components through coordination bonds.MOF-derived materials preserve the large surface area and inherent porosity ...Metal-organic frameworks(MOFs)are porous materials formed by the coordination of organic and inorganic components through coordination bonds.MOF-derived materials preserve the large surface area and inherent porosity of their parent structures,while simultaneously offering enhanced electrical conductivity and more efficient charge transport.Studies have shown that integrating electrospinning with MOFs into continuous nanofiber networks can effectively address issues such as MOF structural collapse,low conductivity,and leaching of active sites.Moreover,the electrospinning technique enables fine-tuning of the product’s morphology,architecture,and chemical composition,thereby unlocking new possibilities for advancing high-performance ZABs.This review provides a systematic overview of recent advances in non-precious metal electrocatalysts derived from electrospun-MOF composites and examines the unique advantages of combining electrospinning with MOF precursors in the design of oxygen electrocatalysts.It also investigates the morphological regulation of various fiber structures,including porous,hollow,core-shell,and beaded structures,as well as their influence on the catalytic performance.Finally,the performance enhancement strategies of electrospun-MOF catalyst materials are examined,and the development prospects along with future research directions related to oxygen electrocatalysts based on electrospun nanofibers are emphasized.This thorough review aims to offer meaningful insights and practical guidance for advancing the understanding,design,and fabrication of next-generation devices for energy conversion and storage.展开更多
Obesity is a major focus of researchers due to its increasing prevalence and relationship with other diseases,such as cancer and cardiovascular diseases.Probiotics are active microorganisms and have been proven to all...Obesity is a major focus of researchers due to its increasing prevalence and relationship with other diseases,such as cancer and cardiovascular diseases.Probiotics are active microorganisms and have been proven to alleviate obesity by modulating the microbiota.In this study,we found that oral administration of Bifidobacterium adolescentis CCFM8630 to obese mice inhibited high-fat diet(HFD)-induced changes in body weight and adipose tissue and alleviated hepatic oxidative stress.Furthermore,B.adolescentis CCFM8630 treatment primarily affected the relative abundances of the phyla Proteobacteria and Actinobacteria,and thereby decreased the production of lipopolysaccharide(LPS)and the occurrence of LPS related diseases.A high fiber intake increased the abundance of Lactobacillus and the concentrations of short chain fatty acids in obese mice,but these changes were reversed by B.adolescentis CCFM8630 treatment.In addition,targeted metabolomic analysis and microbiota relationship analysis revealed that B.adolescentis CCFM8630 treatment modified the microbiota of obese mice by promoting the conversion of tryptophan(Trp)to xanthurenic acid,kynurenic acid,tryptamine,indole-3-acetic acid,and indole-3-carboxaldehyde;facilitated the expression of interleukin-17A and the aryl hydrocarbon receptor to generate interleukin-22 in the colon;and upregulated the expression of tight junction proteins,thereby strengthening intestinal barriers.In summary,our findings suggest that the intake of B.adolescentis CCFM8630 may alleviate obesity by modulating the gut microbiota and related Trp metabolism.展开更多
Sequential indicator simulation is a commonly used method for discrete variable simulation in 3D geological modeling and a widely used stochastic simulation method, which can be used not only for continuous variable s...Sequential indicator simulation is a commonly used method for discrete variable simulation in 3D geological modeling and a widely used stochastic simulation method, which can be used not only for continuous variable simulation but also for discrete variable simulation. In this paper, the X Oilfield in the western South China Sea is taken as an example to compare the sequential indicator simulation method and the Indicator Kriging interpolation method. The results of the final comparison show that the results of the lithofacies model established by the Indicator Kriging deterministic interpolation method are overly smooth, and its coincidence rate with the geological statistical results is not high, thus cannot well reflect the heterogeneity of the underground reservoir, while the simulation results of the lithofacies model established by the sequential indicator stochastic simulation method can fit well with the statistical law of the well, which has eliminated the smoothing effect of Kriging interpolation, thus can better reflect the heterogeneity of the underground reservoir. Therefore, the sequential indicator simulation is more suitable for the characterization of sand bodies and the study of reservoir heterogeneity.展开更多
The optimal guidance problem for an interceptor against a ballistic missile with active defense is investigated in this paper.A class of optimal guidance schemes are proposed based on linear quadratic differential gam...The optimal guidance problem for an interceptor against a ballistic missile with active defense is investigated in this paper.A class of optimal guidance schemes are proposed based on linear quadratic differential game method and numerical solution of Riccati differential equation.By choosing proper parameters, the proposed guidance schemes are able to drive the interceptor to the target and away from the defender simultaneously.Additionally, fuel cost, control saturation,chattering phenomenon and parameters selection were taken into account.Satisfaction of the proposed guidance schemes of the saddle point condition is proven theoretically.Finally, nonlinear numerical examples are included to demonstrate the effectiveness and performance of the developed guidance approaches.Comparison of control performance between different guidance schemes are presented and analysis.展开更多
In this study,N-doped porous carbons were produced with commercial phenolic resin as the raw material,urea as the nitrogen source and KOH as the activation agent.Different from conventional carbonization-nitriding-act...In this study,N-doped porous carbons were produced with commercial phenolic resin as the raw material,urea as the nitrogen source and KOH as the activation agent.Different from conventional carbonization-nitriding-activation three-step method,a facile two-step process was explored to produce N-incorporated porous carbons.The as-obtained adsorbents hold superior CO2 uptake,i.e.5.01 and 7.47 mmol/g at 25℃and 0℃under 1 bar,respectively.The synergistic effects of N species on the surface and narrow micropores of the adsorbents decide their CO2 uptake under 25℃and atmospheric pressure.These phenolic resin-derived adsorbents also possess many extremely promising CO2 adsorption features like good recyclability,quick adsorption kinetics,modest heat of adsorption,great selectivity of CO2 over N2 and outstanding dynamic adsorption capacity.Cheap precursor,easy preparation strategy and excellent CO2 adsorption properties make these phenolic resin-derived N-doped carbonaceous adsorbents highly promising in CO2 capture.展开更多
To facilitate the electrochemical CO_(2) reduction(ECR)to fuels and valuable chemicals,the development of active,low cost,and selective catalysts is crucial.We report a novel ECR catalyst consisting of CuO nanoparticl...To facilitate the electrochemical CO_(2) reduction(ECR)to fuels and valuable chemicals,the development of active,low cost,and selective catalysts is crucial.We report a novel ECR catalyst consisting of CuO nanoparticles with sizes ranging from 1.4 to 3.3 nm anchored on Cu metal‐organic framework(Cu‐MOF)nanosheets obtained through a one‐step facile solvothermal method.The nanocomposites provide multiple sites for efficient ambient ECR,delivering an average C_(2)H_(4) faradaic efficiency(FE)of~50.0%at–1.1 V(referred to the reversible hydrogen electrode)in 0.1 mol/L aqueous KHCO_(3) using a two‐compartment cell,in stark contrast to a C_(2)H_(4) FE of 25.5%and 37.6%over individual CuO and Cu‐MOF respectively,also surpassing most newly reported Cu‐based materials under similar cathodic voltages.The C_(2)H_(4) FE remains at over 45.0%even after 10.0 h of successive polarization.Also,a~7.0 mA cm^(–2) C_(2)H_(4) partial geometric current density and 27.7%half‐cell C_(2)H_(4) power conversion efficiency are achieved.The good electrocatalytic performance can be attributed to the interface between CuO and Cu‐MOF,with accessible metallic moieties and the unique two‐dimensional structure of the Cu‐MOF enhancing the adsorption and activation of CO_(2) molecules.This finding offers a simple avenue to upgrading CO_(2) to value‐added hydrocarbons by rational design of MOF‐based composites.展开更多
This paper focuses on the sensor subset optimization problem in time difference of arrival(TDOA) passive localization scenario. We seek for the best sensor combination by formulating a non-convex optimization problem,...This paper focuses on the sensor subset optimization problem in time difference of arrival(TDOA) passive localization scenario. We seek for the best sensor combination by formulating a non-convex optimization problem, which is to minimize the trace of covariance matrix of localization error under the condition that the number of selected sensors is given. The accuracy metric is described by the localization error covariance matrix of classical closed-form solution, which is introduced to convert the TDOA nonlinear equations into pseudo linear equations. The non-convex optimization problem is relaxed to a standard semi-definite program(SDP) and efficiently solved in a short time. In addition, we extend the sensor selection method to a mixed TDOA and angle of arrival(AOA) localization scenario with the presence of sensor position errors. Simulation results validate that the performance of the proposed sensor selection method is very close to the exhaustive search method.展开更多
基金supported by Guangdong Province Rural Science and Technology Commissioner Project,Zen Tea Reliable Traceability and Intelligent Planting Key Technology Research and Development,Promotion and Application(KTP20210199)Special Project of Guangdong Provincial Education Department,Research on Abnormal Behavior Recognition Technology of Pregnant Sows Based onGraph Convolution(2021ZDZX1091)+2 种基金Guangdong Basic and Applied Basic Research Foundation under Grant 2023A1515110729Shenzhen Science and Technology Program under Grant 20231128093642002the Research Foundation of Shenzhen Polytechnic University under Grant 6023312007K.
文摘This paper introduces an advanced and efficient method for distributed drone-based fruit recognition and localization, tailored to satisfy the precision and security requirements of autonomous agricultural operations. Our method incorporates depth information to ensure precise localization and utilizes a streamlined detection network centered on the RepVGG module. This module replaces the traditional C2f module, enhancing detection performance while maintaining speed. To bolster the detection of small, distant fruits in complex settings, we integrate Selective Kernel Attention (SKAttention) and a specialized small-target detection layer. This adaptation allows the system to manage difficult conditions, such as variable lighting and obstructive foliage. To reinforce security, the tasks of recognition and localization are distributed among multiple drones, enhancing resilience against tampering and data manipulation. This distribution also optimizes resource allocation through collaborative processing. The model remains lightweight and is optimized for rapid and accurate detection, which is essential for real-time applications. Our proposed system, validated with a D435 depth camera, achieves a mean Average Precision (mAP) of 0.943 and a frame rate of 169 FPS, which represents a significant improvement over the baseline by 0.039 percentage points and 25 FPS, respectively. Additionally, the average localization error is reduced to 0.82 cm, highlighting the model’s high precision. These enhancements render our system highly effective for secure, autonomous fruit-picking operations, effectively addressing significant performance and cybersecurity challenges in agriculture. This approach establishes a foundation for reliable, efficient, and secure distributed fruit-picking applications, facilitating the advancement of autonomous systems in contemporary agricultural practices.
文摘Background: Recent obstetrical practice tends to avoid the use of manual uterine fundal pressure (MUFP);however, data showed that MUFP is actually employed. We here attempted 1) to determine the obstetricians’ attitudes towards MUFP via questionnaire, and 2) to examine whether MUFP shortens the 2nd stage of labor, with the latter tested as a pilot study. Methods: A questionnaire-based study was carried out (n = 122) at meetings of Obstetrics on May 5, 2017. Then, we conducted a pilot case-control study from August 23 to September 6, 2020. Participants (n = 29) were divided into two groups;women who did and did not want MUFP;i.e., MUFP (n = 14) vs. (Non-MUFP) group (n = 15). Results: Of 122 doctors, 99.18% (121/122) used MUFP at cesarean section. 95.90% (117/122) of institutions used MUFP in spontaneous delivery. 95.08% (116/122) obstetricians considered MUFP effective and helpful. 85.24% (104/122) considered that MUFP should be employed after station +3. In the case control study, MUFP vs. Non-MUFP group showed the second-stage-duration of 58.5 (50.25 - 71.25) vs. 48 (39 - 59) minutes, without statistical significance (P = 0.101). However, importantly, MUFP, compared with Non-MUFP group, showed a significantly shorter duration from head visible on introitus (apparition) to delivery;i.e., 21.26 ± 7.32 vs. 30.13 ± 10.61 minutes (P = 0.014). Conclusions: MUFP is still used widely and MUFP shortened the duration of head apparition to delivery time. Larger-sample studies are needed to confirm the efficacy and safety of MUFP.
基金supported by the National Natural Science Foundation of China(32272332,32021005)the Fundamental Research Funds for the Central Universities(JUSRP622020,JUSRP22006,and JUSRP51501)+2 种基金the Program of Collaborative Innovation Centre of Food Safety and Quality Control in Jiangsu ProvinceTop Talent Support Program for Young and Middle-aged People of Wuxi Health Committee(bj2020111)Appropriate Technology Promotion Project of Wuxi Municipal Health Commission(FYTG202006)。
文摘Gestational diabetes mellitus(GDM)is a disease of glucose intolerance that first occurs during pregnancy.Accumulating evidence underlined a link between gut microbiota dysbiosis and GDM,and microbial metabolites represent a unique way to explore microbiota-host interactions.However,the associations between changes in the gut microbiota and microbial metabolites and immune homeostasis in the GDM pathogenesis remain largely unclear.In this prospective study,the characteristics of gut microbiota in both first trimester(T1)and second trimester(T2)were investigated in 46 GDM patients and 44 matched controls.We comprehensively profiled the microbial metabolites using non-targeted metabolomics and quantitatively targeted metabolomics,measurements of inflammatory cytokines and biomarkers of intestinal barrier function,and combined with correlation analysis in T2.Gut microbiota dybiosis was observed in GDM patients in both T1 and T2,and was characterised by the enrichment of multiple potentially harmful bacteria,such as UBA1819 and Erysipelatoclostridium.Besides,alterations in the microbiota were accompanied by a disturbance in tryptophan metabolism,mainly manifested as a shift towards the production of more kynurenine and less indole derivatives.Most importantly,correlation network analysis indicated that overgrowth of potential pathogens and tryptophan metabolism disorder were associated with inflammatory imbalance and disrupted epithelial barrier in GDM patients.These findings provide a greater understanding of the pathogenesis and new targets for microecological interventions by mediating tryptophan metabolism in GDM.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0760200)the National Natural Science Foundation of China(Grant Nos.42330605 and 42377101).
文摘The Beijing 325 m meteorological tower stands as a pivotal research platform for exploring atmospheric boundary layer physics and atmospheric chemistry.With a legacy spanning 45 years,the tower has played a crucial role in unraveling the complexities of urban air pollution,atmospheric processes,and climate change in Beijing,China.This review paper provides a comprehensive overview of the measurements on the tower over the past two decades.Through long-term comprehensive observations,researchers have elucidated the intricate relationships between anthropogenic emissions,meteorological dynamics,and atmospheric composition,shedding light on the drivers of air pollution and its impacts on public health.The vertical measurements on the tower also enable detailed investigations into boundary layer dynamics,turbulent mixing,and pollutant dispersion,providing invaluable data for validating chemical transport models.Key findings from the tower’s research include the identification of positive feedback mechanisms between aerosols and the boundary layer,the characterization of pollutant sources and transport pathways,the determination of fluxes of gaseous and particulate species,and the assessment of the effectiveness of pollution control measures.Additionally,isotopic measurements have provided new insights into the sources and formation processes of particulate matter and reactive nitrogen species.Finally,the paper outlines future directions for tower-based research,emphasizing the need for long-term comprehensive measurements,the development of innovative tower platforms,and integration of emerging technologies.
基金supported by Zhao Guoping Academician Workstation(Hangzhou Academician Workstation)of Zhejiang Chinese Medical University,Chinese Academy of Sciences-the Alliance of National and International Science Organizations for the Belt and Road Regions Fellowship(CAS-ANSO-FP-2024-06)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB1060000)the Science and Technology Commission of Shanghai Municipality(No.YDZX20233100004032001,China).
文摘Cerebral edema is characterized by fluid accumulation,and the glymphatic system(GS)plays a pivotal role in regulating fluid transport.Using the Tenecteplase system,magnesium salt of salvianolic acid B/ginsenoside Rg1(SalB/Rg1)was injected intravenously into mice 4.5 h after middle cerebral artery occlusion and once every 24 h for the following 72 h.GS function was assessed by Evans blue imaging,near-infrared fluorescence region II(NIR-II)imaging,and magnetic resonance imaging(MRI).SalB/Rg1 had significant effects on reducing the infarct volume and hemorrhagic transformation score,improving neurobehavioral function,and protecting tissue structure,especially inhibiting cerebral edema.Meanwhile,the influx/efflux drainage of GS was enhanced by SalB/Rg1 according to NIR-II imaging and MRI.SalB/Rg1 inhibited matrix metalloproteinase-9(MMP-9)activity,reduced cleavedβ-dystroglycan(β-DG),and stabilized aquaporin-4(AQP4)polarity,which was verified by colocalization with CD31.Our findings indicated that SalB/Rg1 treatment enhances GS function and attenuates cerebral edema,accompanying the regulation of the MMP9/β-DG/AQP4 pathway.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(grant No.XDA0350502)the National SKA Program of China(No.2020SKA0120103)the National Natural Science Foundation of China(No.U1831130).
文摘Determining accurate pulsar timing model parameters is essential for establishing TT(PT),a realization of Terrestrial Time(TT)based on a pulsar timescale(PT).This study discusses the impact of different data spans on the accuracy of pulsar timing model parameters when determining pulsar timing model parameters.Using observations of PSR J0437-4715,J1909-3744,J1713+0747,and J1744-1134 from the second data release of the International Pulsar Timing Array(IPTA II,Version A),we compare the accuracy of the timing model parameters determined by these observations with different data spans.The results show for PSR J0437-4715,J1713+0747,and J1909-3744,the amplitude fluctuations of rotational frequency remain within 10^(−15),10^(−14),and 10^(−14) Hz,respectively,when the data spans for determining pulsar timing model parameters exceed 13,14,and 6 yr.Additionally,the one-year accuracy of TT(PT)is crucial for its application in timekeeping.By comparing the frequency deviations of TT(PT)relative to TT(BIPM)under both ideal(k_(r))and actual(k_(p))conditions across different data spans,we find that when the data span reaches the duration above,the accuracy of TT(PT)surpasses that of TT(TAI)under ideal conditions,slightly inferior under actual conditions.This suggests with improved observational technologies,the accuracy of TT(PT)can be further enhanced.
基金supported by the National Key Research and Development Program,Ministry of Science and Technology of the People's Republic of China(Grant No.2021YFC2701001)the National Natural Science Foundation of China(Grant No.81973056).
文摘Objective Exposure to polycyclic aromatic hydrocarbons(PAHs)or metal(loid)s individually has been associated with neural tube defects(NTDs).However,the impacts of PAH and metal(loid)co-exposure and potential interaction effects on NTD risk remain unclear.We conducted a case-control study in China among population with a high prevalence of NTDs to investigate the combined effects of PAH and metal(loid)exposures on the risk of NTD.Methods Cases included 80 women who gave birth to offspring with NTDs,whereas controls were 50 women who delivered infants with no congenital malformations.We analyzed the levels of placental PAHs using gas chromatography and mass spectrometry,PAH-DNA adducts with 32P-post-labeling method,and metal(loid)s with an inductively coupled plasma mass spectrometer.Unconditional logistic regression was employed to estimate the associations between individual exposures and NTDs.Least absolute shrinkage and selection operator(LASSO)penalized regression models were used to select a subset of exposures,while additive interaction models were used to identify interaction effects.Results In the single-exposure models,we found that eight PAHs,PAH-DNA adducts,and 28 metal(loid)s were associated with NTDs.Pyrene,selenium,molybdenum,cadmium,uranium,and rubidium were selected through LASSO regression and were statistically associated with NTDs in the multiple-exposure models.Women with high levels of pyrene and molybdenum or pyrene and selenium exhibited significantly increased risk of having offspring with NTDs,indicating that these combinations may have synergistic effects on the risk of NTDs.Conclusion Our findings suggest that individual PAHs and metal(loid)s,as well as their interactions,may be associated with the risk of NTDs,which warrants further investigation.
文摘Metal-organic frameworks(MOFs)are porous materials formed by the coordination of organic and inorganic components through coordination bonds.MOF-derived materials preserve the large surface area and inherent porosity of their parent structures,while simultaneously offering enhanced electrical conductivity and more efficient charge transport.Studies have shown that integrating electrospinning with MOFs into continuous nanofiber networks can effectively address issues such as MOF structural collapse,low conductivity,and leaching of active sites.Moreover,the electrospinning technique enables fine-tuning of the product’s morphology,architecture,and chemical composition,thereby unlocking new possibilities for advancing high-performance ZABs.This review provides a systematic overview of recent advances in non-precious metal electrocatalysts derived from electrospun-MOF composites and examines the unique advantages of combining electrospinning with MOF precursors in the design of oxygen electrocatalysts.It also investigates the morphological regulation of various fiber structures,including porous,hollow,core-shell,and beaded structures,as well as their influence on the catalytic performance.Finally,the performance enhancement strategies of electrospun-MOF catalyst materials are examined,and the development prospects along with future research directions related to oxygen electrocatalysts based on electrospun nanofibers are emphasized.This thorough review aims to offer meaningful insights and practical guidance for advancing the understanding,design,and fabrication of next-generation devices for energy conversion and storage.
基金supported by the National Natural Science Foundation of China(32272332,32021005,31820103010)the Fundamental Research Funds for the Central Universities(JUSRP622020,JUSRP22006,JUSRP51501)the Program of Collaborative Innovation Centre of Food Safety and Quality Control in Jiangsu Province.
文摘Obesity is a major focus of researchers due to its increasing prevalence and relationship with other diseases,such as cancer and cardiovascular diseases.Probiotics are active microorganisms and have been proven to alleviate obesity by modulating the microbiota.In this study,we found that oral administration of Bifidobacterium adolescentis CCFM8630 to obese mice inhibited high-fat diet(HFD)-induced changes in body weight and adipose tissue and alleviated hepatic oxidative stress.Furthermore,B.adolescentis CCFM8630 treatment primarily affected the relative abundances of the phyla Proteobacteria and Actinobacteria,and thereby decreased the production of lipopolysaccharide(LPS)and the occurrence of LPS related diseases.A high fiber intake increased the abundance of Lactobacillus and the concentrations of short chain fatty acids in obese mice,but these changes were reversed by B.adolescentis CCFM8630 treatment.In addition,targeted metabolomic analysis and microbiota relationship analysis revealed that B.adolescentis CCFM8630 treatment modified the microbiota of obese mice by promoting the conversion of tryptophan(Trp)to xanthurenic acid,kynurenic acid,tryptamine,indole-3-acetic acid,and indole-3-carboxaldehyde;facilitated the expression of interleukin-17A and the aryl hydrocarbon receptor to generate interleukin-22 in the colon;and upregulated the expression of tight junction proteins,thereby strengthening intestinal barriers.In summary,our findings suggest that the intake of B.adolescentis CCFM8630 may alleviate obesity by modulating the gut microbiota and related Trp metabolism.
文摘Sequential indicator simulation is a commonly used method for discrete variable simulation in 3D geological modeling and a widely used stochastic simulation method, which can be used not only for continuous variable simulation but also for discrete variable simulation. In this paper, the X Oilfield in the western South China Sea is taken as an example to compare the sequential indicator simulation method and the Indicator Kriging interpolation method. The results of the final comparison show that the results of the lithofacies model established by the Indicator Kriging deterministic interpolation method are overly smooth, and its coincidence rate with the geological statistical results is not high, thus cannot well reflect the heterogeneity of the underground reservoir, while the simulation results of the lithofacies model established by the sequential indicator stochastic simulation method can fit well with the statistical law of the well, which has eliminated the smoothing effect of Kriging interpolation, thus can better reflect the heterogeneity of the underground reservoir. Therefore, the sequential indicator simulation is more suitable for the characterization of sand bodies and the study of reservoir heterogeneity.
文摘The optimal guidance problem for an interceptor against a ballistic missile with active defense is investigated in this paper.A class of optimal guidance schemes are proposed based on linear quadratic differential game method and numerical solution of Riccati differential equation.By choosing proper parameters, the proposed guidance schemes are able to drive the interceptor to the target and away from the defender simultaneously.Additionally, fuel cost, control saturation,chattering phenomenon and parameters selection were taken into account.Satisfaction of the proposed guidance schemes of the saddle point condition is proven theoretically.Finally, nonlinear numerical examples are included to demonstrate the effectiveness and performance of the developed guidance approaches.Comparison of control performance between different guidance schemes are presented and analysis.
基金supported by the Zhejiang Provincial Natural Sci-ence Foundation(No LQ17B060001)the National Natural Science Foundation of China(No 21706239)National Undergraduate Training Program for Innovation and Entrepreneurship of China。
文摘In this study,N-doped porous carbons were produced with commercial phenolic resin as the raw material,urea as the nitrogen source and KOH as the activation agent.Different from conventional carbonization-nitriding-activation three-step method,a facile two-step process was explored to produce N-incorporated porous carbons.The as-obtained adsorbents hold superior CO2 uptake,i.e.5.01 and 7.47 mmol/g at 25℃and 0℃under 1 bar,respectively.The synergistic effects of N species on the surface and narrow micropores of the adsorbents decide their CO2 uptake under 25℃and atmospheric pressure.These phenolic resin-derived adsorbents also possess many extremely promising CO2 adsorption features like good recyclability,quick adsorption kinetics,modest heat of adsorption,great selectivity of CO2 over N2 and outstanding dynamic adsorption capacity.Cheap precursor,easy preparation strategy and excellent CO2 adsorption properties make these phenolic resin-derived N-doped carbonaceous adsorbents highly promising in CO2 capture.
文摘To facilitate the electrochemical CO_(2) reduction(ECR)to fuels and valuable chemicals,the development of active,low cost,and selective catalysts is crucial.We report a novel ECR catalyst consisting of CuO nanoparticles with sizes ranging from 1.4 to 3.3 nm anchored on Cu metal‐organic framework(Cu‐MOF)nanosheets obtained through a one‐step facile solvothermal method.The nanocomposites provide multiple sites for efficient ambient ECR,delivering an average C_(2)H_(4) faradaic efficiency(FE)of~50.0%at–1.1 V(referred to the reversible hydrogen electrode)in 0.1 mol/L aqueous KHCO_(3) using a two‐compartment cell,in stark contrast to a C_(2)H_(4) FE of 25.5%and 37.6%over individual CuO and Cu‐MOF respectively,also surpassing most newly reported Cu‐based materials under similar cathodic voltages.The C_(2)H_(4) FE remains at over 45.0%even after 10.0 h of successive polarization.Also,a~7.0 mA cm^(–2) C_(2)H_(4) partial geometric current density and 27.7%half‐cell C_(2)H_(4) power conversion efficiency are achieved.The good electrocatalytic performance can be attributed to the interface between CuO and Cu‐MOF,with accessible metallic moieties and the unique two‐dimensional structure of the Cu‐MOF enhancing the adsorption and activation of CO_(2) molecules.This finding offers a simple avenue to upgrading CO_(2) to value‐added hydrocarbons by rational design of MOF‐based composites.
基金supported by the National Natural Science Foundation of China under Grant (61631015, 61501354 61471395 and 61501356)the Key Scientific and Technological Innovation Team Plan (2016KCT-01)the Fundamental Research Funds of the Ministry of Education (7215433803 and XJS16063)
文摘This paper focuses on the sensor subset optimization problem in time difference of arrival(TDOA) passive localization scenario. We seek for the best sensor combination by formulating a non-convex optimization problem, which is to minimize the trace of covariance matrix of localization error under the condition that the number of selected sensors is given. The accuracy metric is described by the localization error covariance matrix of classical closed-form solution, which is introduced to convert the TDOA nonlinear equations into pseudo linear equations. The non-convex optimization problem is relaxed to a standard semi-definite program(SDP) and efficiently solved in a short time. In addition, we extend the sensor selection method to a mixed TDOA and angle of arrival(AOA) localization scenario with the presence of sensor position errors. Simulation results validate that the performance of the proposed sensor selection method is very close to the exhaustive search method.
