基于生理的动力学(physiologically based kinetic,PBK)模型是一种用于模拟化学物质在有机体(如人类和其他动物物种)中的生物过程(吸收、分布、代谢和排泄,简称ADME)和推导体内、外剂量或靶器官剂量的工具。相较于PBK在药物研发的不同...基于生理的动力学(physiologically based kinetic,PBK)模型是一种用于模拟化学物质在有机体(如人类和其他动物物种)中的生物过程(吸收、分布、代谢和排泄,简称ADME)和推导体内、外剂量或靶器官剂量的工具。相较于PBK在药物研发的不同阶段的广泛应用,近几年来PBK在化学物质管理中应用的发展更为迅速。在过去十几年中,化学品安全管理领域的不同国际组织和权威机构相继发布了关于合理构建和使用PBK模型的指导文件。本文主要总结了人类/哺乳动物的PBK模型构建、化学物质健康风险评估中常用的软件和平台,以及PBK模型软件在化学物质管理中的应用和相关案例,简述了基于PBK和体外-体内外推(IVIVE)方法在下一代健康风险评估中的应用潜力,并对PBK在中国化学物质管理应用中需要解决的科学问题进行了讨论,以期为PBK在我国化学物质管理应用提供借鉴。展开更多
The achievement of electrical spin control is highly desirable.One promising strategy involves electrically mod-ulating the Rashba spin orbital coupling effect in materials.A semiconductor with high sensitivity in its...The achievement of electrical spin control is highly desirable.One promising strategy involves electrically mod-ulating the Rashba spin orbital coupling effect in materials.A semiconductor with high sensitivity in its Rashba constant to external electric fields holds great potential for short channel lengths in spin field-effect transistors,which is crucial for preserving spin coherence and enhancing integration density.Hence,two-dimensional(2D)Rashba semiconductors with large Rashba constants and significant electric field responses are highly desirable.Herein,by employing first-principles calculations,we design a thermodynamically stable 2D Rashba semiconductor,YSbTe_(3),which possesses an indirect band gap of 1.04 eV,a large Rashba constant of 1.54 eV·Åand a strong electric field response of up to 4.80 e·Å^(2).In particular,the Rashba constant dependence on the electric field shows an unusual nonlinear relationship.At the same time,YSbTe_(3)has been identified as a 2D ferroelectric material with a moderate polarization switching energy barrier(~0.33 eV per formula).By changing the electric polarization direction,the Rashba spin texture of YSbTe_(3)can be reversed.These out-standing properties make the ferroelectric Rashba semiconductor YSbTe_(3)quite promising for spintronic applications.展开更多
The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nick...The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins.展开更多
The breakage and bending of ducts result in a difficulty to cope with ventilation issues in bidirectional excavation tunnels with a long inclined shaft using a single ventilation method based on ducts.To discuss the h...The breakage and bending of ducts result in a difficulty to cope with ventilation issues in bidirectional excavation tunnels with a long inclined shaft using a single ventilation method based on ducts.To discuss the hybrid ventilation system applied in bidirectional excavation tunnels with a long inclined shaft,this study has established a full-scale computational fluid dynamics model based on field tests,the Poly-Hexcore method,and the sliding mesh technique.The distribution of wind speed,temperature field,and CO in the tunnel are taken as indices to compare the ventilation efficiency of three ventilation systems(duct,duct-ventilation shaft,duct–ventilated shaft-axial fan).The results show that the hybrid ventilation scheme based on duct-ventilation shaft–axial fan performs the best among the three ventilation systems.Compared to the duct,the wind speed and cooling rate in the tunnel are enhanced by 7.5%–30.6%and 14.1%–17.7%,respectively,for the duct-vent shaft-axial fan condition,and the volume fractions of CO are reduced by 26.9%–73.9%.This contributes to the effective design of combined ventilation for bidirectional excavation tunnels with an inclined shaft,ultimately improving the air quality within the tunnel.展开更多
Many digital platforms have employed free-content promotion strategies to deal with the high uncertainty levels regarding digital content products.However,the diversity of digital content products and user heterogenei...Many digital platforms have employed free-content promotion strategies to deal with the high uncertainty levels regarding digital content products.However,the diversity of digital content products and user heterogeneity in content preference may blur the impact of platform promotions across users and products.Therefore,free-content promotion strategies should be adapted to allocate marketing resources optimally and increase revenue.This study develops personal-ized free-content promotion strategies based on individual-level heterogeneous treatment effects and explores the causes of their heterogeneity,focusing on the moderating effect of user engagement-related variables.To this end,we utilize ran-dom field experimental data provided by a top Chinese e-book platform.We employ a framework that combines machine learning with econometric causal inference methods to estimate individual treatment effects and analyze their potential mechanisms.The analysis shows that,on average,free-content promotions lead to a significant increase in consumer pay-ments.However,the higher the level of user engagement,the lower the payment lift caused by promotions,as more-engaged users are more strongly affected by the cannibalization effect of free-content promotion.This study introduces a novel causal research design to help platforms improve their marketing strategies.展开更多
Objective:Healthcare workers,as a high-stress professional group,face long-term high intensity workloads and complex medical environments,resulting in increasingly prominent mental health issues.In particular,the wide...Objective:Healthcare workers,as a high-stress professional group,face long-term high intensity workloads and complex medical environments,resulting in increasingly prominent mental health issues.In particular,the widespread presence of anxiety symptoms and somatic pain has become a major factor affecting both the quality of care and the career development of healthcare workers.This study aims to investigate the mediating and moderating roles of psychological resilience and sleep in the relationship between somatic pain and anxiety among healthcare workers.Methods:A cross-sectional questionnaire survey was conducted among 1661 healthcare workers.The instruments used included the Generalized Anxiety Disorder-7(GAD-7),item 3 from the Patient Health Questionnaire-9(PHQ-9),the 10-item Connor-Davidson Resilience Scale(CD-RISC-10)for psychological resilience,and the Visual Analogue Scale(VAS)for assessing anxiety,sleep disturbance,psychological resilience,and somatic pain.Results:The detection rate of anxiety symptoms among healthcare workers was 38.95%.Psychological resilience was significantly negatively correlated with anxiety symptoms(r=−0.451,P<0.01),sleep disturbance(r=−0.313,P<0.01),and somatic pain(r=−0.214,P<0.01).Moreover,psychological resilience partially mediated the relationship between somatic pain and anxiety(β=−0.103,P<0.01),and sleep quality moderated the latter part of the mediation model(“somatic pain-psychological resilience-anxiety”).Conclusion:Under high-intensity workloads,healthcare workers generally experience severe anxiety symptoms.Psychological resilience plays an important protective mediating role in their mental health,and sleep quality serves as a moderator in this relationship.Enhancing healthcare workers’psychological resilience and improving their sleep may promote both their physical and mental well-being.展开更多
The time-dependent behaviors of coal and rocks were easily ignored. Besides, “three-stage” triaxial loading and unloading mechanics tests of sandstone were conducted based on the idea of the initial high in-situ str...The time-dependent behaviors of coal and rocks were easily ignored. Besides, “three-stage” triaxial loading and unloading mechanics tests of sandstone were conducted based on the idea of the initial high in-situ stress state recovery according to the full-life cycle evolution characteristics of surrounding rocks in deep mines(pre-excavation,excavation and post-excavation). The time-dependent stress-strain curves of sandstone were obtained. Meanwhile, the deformation and strength fitting relationships with time of sandstone were also built. Furthermore, the dilatancy and volumetric recovery mechanical mechanisms of sandstone were revealed. The results showed that: 1) There were significant time-dependent evolution characteristics on the deformation and strength of sandstone;2) There were significant correlations among the internal friction angle, cohesion and the simulated depths;3) Volumetric recovery phenomenon of sandstone was observed for the first time, which mainly occurred at the simulated depth of 2000 m. The above research conclusions could provide a certain theoretical basis for the stability control of surrounding rocks in deep mines.展开更多
文摘基于生理的动力学(physiologically based kinetic,PBK)模型是一种用于模拟化学物质在有机体(如人类和其他动物物种)中的生物过程(吸收、分布、代谢和排泄,简称ADME)和推导体内、外剂量或靶器官剂量的工具。相较于PBK在药物研发的不同阶段的广泛应用,近几年来PBK在化学物质管理中应用的发展更为迅速。在过去十几年中,化学品安全管理领域的不同国际组织和权威机构相继发布了关于合理构建和使用PBK模型的指导文件。本文主要总结了人类/哺乳动物的PBK模型构建、化学物质健康风险评估中常用的软件和平台,以及PBK模型软件在化学物质管理中的应用和相关案例,简述了基于PBK和体外-体内外推(IVIVE)方法在下一代健康风险评估中的应用潜力,并对PBK在中国化学物质管理应用中需要解决的科学问题进行了讨论,以期为PBK在我国化学物质管理应用提供借鉴。
基金supported by the National Natural Science Foundation of China(22322304,22273092,22373095)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0450101)+2 种基金the Innovation Program for Quantum Science and Technology(2021ZD0303306)the USTC Tang ScholarThe authors wish to acknowledge the Supercomputing Center of the USTC for providing computational resources.
文摘The achievement of electrical spin control is highly desirable.One promising strategy involves electrically mod-ulating the Rashba spin orbital coupling effect in materials.A semiconductor with high sensitivity in its Rashba constant to external electric fields holds great potential for short channel lengths in spin field-effect transistors,which is crucial for preserving spin coherence and enhancing integration density.Hence,two-dimensional(2D)Rashba semiconductors with large Rashba constants and significant electric field responses are highly desirable.Herein,by employing first-principles calculations,we design a thermodynamically stable 2D Rashba semiconductor,YSbTe_(3),which possesses an indirect band gap of 1.04 eV,a large Rashba constant of 1.54 eV·Åand a strong electric field response of up to 4.80 e·Å^(2).In particular,the Rashba constant dependence on the electric field shows an unusual nonlinear relationship.At the same time,YSbTe_(3)has been identified as a 2D ferroelectric material with a moderate polarization switching energy barrier(~0.33 eV per formula).By changing the electric polarization direction,the Rashba spin texture of YSbTe_(3)can be reversed.These out-standing properties make the ferroelectric Rashba semiconductor YSbTe_(3)quite promising for spintronic applications.
基金supported by the National Key R&D Program of China(2021YFA1501700)Fundamental Research Funds for the Central Universities(WK9990000142).
文摘The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins.
基金Project(N2022G031)supported by the Science and Technology Research and Development Program Project of China RailwayProjects(2022-Key-23,2021-Special-01A)supported by the Science and Technology Research and Development Program Project of China Railway Group LimitedProject(52308419)supported by the National Natural Science Foundation of China。
文摘The breakage and bending of ducts result in a difficulty to cope with ventilation issues in bidirectional excavation tunnels with a long inclined shaft using a single ventilation method based on ducts.To discuss the hybrid ventilation system applied in bidirectional excavation tunnels with a long inclined shaft,this study has established a full-scale computational fluid dynamics model based on field tests,the Poly-Hexcore method,and the sliding mesh technique.The distribution of wind speed,temperature field,and CO in the tunnel are taken as indices to compare the ventilation efficiency of three ventilation systems(duct,duct-ventilation shaft,duct–ventilated shaft-axial fan).The results show that the hybrid ventilation scheme based on duct-ventilation shaft–axial fan performs the best among the three ventilation systems.Compared to the duct,the wind speed and cooling rate in the tunnel are enhanced by 7.5%–30.6%and 14.1%–17.7%,respectively,for the duct-vent shaft-axial fan condition,and the volume fractions of CO are reduced by 26.9%–73.9%.This contributes to the effective design of combined ventilation for bidirectional excavation tunnels with an inclined shaft,ultimately improving the air quality within the tunnel.
基金supported by the Anhui Postdoctoral Scientific Research Program Foundation(2022B579).
文摘Many digital platforms have employed free-content promotion strategies to deal with the high uncertainty levels regarding digital content products.However,the diversity of digital content products and user heterogeneity in content preference may blur the impact of platform promotions across users and products.Therefore,free-content promotion strategies should be adapted to allocate marketing resources optimally and increase revenue.This study develops personal-ized free-content promotion strategies based on individual-level heterogeneous treatment effects and explores the causes of their heterogeneity,focusing on the moderating effect of user engagement-related variables.To this end,we utilize ran-dom field experimental data provided by a top Chinese e-book platform.We employ a framework that combines machine learning with econometric causal inference methods to estimate individual treatment effects and analyze their potential mechanisms.The analysis shows that,on average,free-content promotions lead to a significant increase in consumer pay-ments.However,the higher the level of user engagement,the lower the payment lift caused by promotions,as more-engaged users are more strongly affected by the cannibalization effect of free-content promotion.This study introduces a novel causal research design to help platforms improve their marketing strategies.
基金supported by the Natural Science Foundation of Hunan Province,China(2023JJ60076)。
文摘Objective:Healthcare workers,as a high-stress professional group,face long-term high intensity workloads and complex medical environments,resulting in increasingly prominent mental health issues.In particular,the widespread presence of anxiety symptoms and somatic pain has become a major factor affecting both the quality of care and the career development of healthcare workers.This study aims to investigate the mediating and moderating roles of psychological resilience and sleep in the relationship between somatic pain and anxiety among healthcare workers.Methods:A cross-sectional questionnaire survey was conducted among 1661 healthcare workers.The instruments used included the Generalized Anxiety Disorder-7(GAD-7),item 3 from the Patient Health Questionnaire-9(PHQ-9),the 10-item Connor-Davidson Resilience Scale(CD-RISC-10)for psychological resilience,and the Visual Analogue Scale(VAS)for assessing anxiety,sleep disturbance,psychological resilience,and somatic pain.Results:The detection rate of anxiety symptoms among healthcare workers was 38.95%.Psychological resilience was significantly negatively correlated with anxiety symptoms(r=−0.451,P<0.01),sleep disturbance(r=−0.313,P<0.01),and somatic pain(r=−0.214,P<0.01).Moreover,psychological resilience partially mediated the relationship between somatic pain and anxiety(β=−0.103,P<0.01),and sleep quality moderated the latter part of the mediation model(“somatic pain-psychological resilience-anxiety”).Conclusion:Under high-intensity workloads,healthcare workers generally experience severe anxiety symptoms.Psychological resilience plays an important protective mediating role in their mental health,and sleep quality serves as a moderator in this relationship.Enhancing healthcare workers’psychological resilience and improving their sleep may promote both their physical and mental well-being.
基金Projects(52034009, 51974319) supported by the National Natural Science Foundation of ChinaProject(2020JCB01) supported by the Yue Qi Distinguished Scholar Project of China。
文摘The time-dependent behaviors of coal and rocks were easily ignored. Besides, “three-stage” triaxial loading and unloading mechanics tests of sandstone were conducted based on the idea of the initial high in-situ stress state recovery according to the full-life cycle evolution characteristics of surrounding rocks in deep mines(pre-excavation,excavation and post-excavation). The time-dependent stress-strain curves of sandstone were obtained. Meanwhile, the deformation and strength fitting relationships with time of sandstone were also built. Furthermore, the dilatancy and volumetric recovery mechanical mechanisms of sandstone were revealed. The results showed that: 1) There were significant time-dependent evolution characteristics on the deformation and strength of sandstone;2) There were significant correlations among the internal friction angle, cohesion and the simulated depths;3) Volumetric recovery phenomenon of sandstone was observed for the first time, which mainly occurred at the simulated depth of 2000 m. The above research conclusions could provide a certain theoretical basis for the stability control of surrounding rocks in deep mines.
