Fine particulatematter(PM_(2.5))samples were collected in two neighboring cities,Beijing and Baoding,China.High-concentration events of PM_(2.5) in which the average mass concentration exceeded 75μg/m^(3) were freque...Fine particulatematter(PM_(2.5))samples were collected in two neighboring cities,Beijing and Baoding,China.High-concentration events of PM_(2.5) in which the average mass concentration exceeded 75μg/m^(3) were frequently observed during the heating season.Dispersion Normalized Positive Matrix Factorization was applied for the source apportionment of PM_(2.5) as minimize the dilution effects of meteorology and better reflect the source strengths in these two cities.Secondary nitrate had the highest contribution for Beijing(37.3%),and residential heating/biomass burning was the largest for Baoding(27.1%).Secondary nitrate,mobile,biomass burning,district heating,oil combustion,aged sea salt sources showed significant differences between the heating and non-heating seasons in Beijing for same period(2019.01.10–2019.08.22)(Mann-Whitney Rank Sum Test P<0.05).In case of Baoding,soil,residential heating/biomass burning,incinerator,coal combustion,oil combustion sources showed significant differences.The results of Pearson correlation analysis for the common sources between the two cities showed that long-range transported sources and some sources with seasonal patterns such as oil combustion and soil had high correlation coefficients.Conditional Bivariate Probability Function(CBPF)was used to identify the inflow directions for the sources,and joint-PSCF(Potential Source Contribution Function)was performed to determine the common potential source areas for sources affecting both cities.These models facilitated a more precise verification of city-specific influences on PM_(2.5) sources.The results of this study will aid in prioritizing air pollution mitigation strategies during the heating season and strengthening air quality management to reduce the impact of downwind neighboring cities.展开更多
Objective:International students frequently face psychological adaptation difficulties while studying and living abroad.As an effective psychological resource,positive solitude has been identified as a potential facto...Objective:International students frequently face psychological adaptation difficulties while studying and living abroad.As an effective psychological resource,positive solitude has been identified as a potential factor for improving psychological well-being,but the underlying mechanism linking the two has not been fully explored.The current study aims to explore the relationship between positive solitude and psychological adaptation of international students,with particular emphasis on the intermediary roles of authenticity and loneliness.Methods:A total of 529 international tertiary students(Mage=23.76,SD=5.08;60.68%male)were surveyed using the Positive Solitude Scale(PSS),Authenticity Scale(AS),6-item UCLA Loneliness Scale(ULS-6),and Brief Psychological Adaptation Scale(BPAS).SPSS27.0 was used for descriptive statistical analysis and Pearson correlation analysis.PROCESS macro(Model 6)was employed to test a serial mediation model,in which authenticity and loneliness function as intermediary variables between positive solitude and psychological adaptation.Results:The correlation analysis indicated significant associations among positive solitude,authenticity,loneliness,and psychological adaptation(r=−0.544~0.511).Positive solitude was directly and positively related to psychological adaptation(β=0.132,t=3.609,p<0.001)and indirectly related to psychological adaptation through two pathways:a single mediation via authenticity(indirect effect=0.089)and a serial mediation through authenticity and loneliness(indirect effect=0.062).Loneliness did not serve as a significant mediator(indirect effect=–0.015,95%CI[–0.049,0.019]).The total indirect effect was 0.136.Conclusions:Interventions targeting international students’capacity for experiencing positive solitude and authenticity can help to reduce loneliness and increase psychological adaptation.The findings derived from this study are conducive to understanding the relationship between positive solitude and psychological adaptation,as well as its underlying mechanisms.In addition,the study offers a new perspective for educational management and psychological counseling services for international students.展开更多
This paper deals with homogeneous Dirichlet boundary value problem to a class of porous medium equations with viscoelastic term ∂u/∂t-Δu^(m)+∫^(t)_(0)g(t-s)Δu^(m)(x,s)ds=u^(p),x∈Ω,t≥0,where p>m(m>0).We pro...This paper deals with homogeneous Dirichlet boundary value problem to a class of porous medium equations with viscoelastic term ∂u/∂t-Δu^(m)+∫^(t)_(0)g(t-s)Δu^(m)(x,s)ds=u^(p),x∈Ω,t≥0,where p>m(m>0).We prove that the weak solutions of the above problem blow up in finite time when the initial energy is positive and the function g satisfies suitable conditions.Our result generalizes that of S.A.Messaoudi in[1].展开更多
Objectives This study aimed to explore and clarify the concept of reflective supervision as a professional self-care strategy to create a positive Intensive Care Unit(ICU)practice environment.Methods Walker and Avant...Objectives This study aimed to explore and clarify the concept of reflective supervision as a professional self-care strategy to create a positive Intensive Care Unit(ICU)practice environment.Methods Walker and Avant’s eight-step concept analysis approach was utilized to identify and define the attributes,antecedents,and consequences of reflective supervision in the ICU.An extensive literature search was conducted across various databases,including Google Scholar,CINAHL,PubMed.Articles published from 2005 to 2025 were identified.We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)2020 statement to indicate the included articles and extract related data based on relevance.Results Forty articles were included in the analysis.The identified attributes included the supervisor-supervisee relationship,effective communication,teamwork,collaborations,reflection,competencies,feedback,continuous support,and autonomous choice.The identified antecedents included participation,supportive supervision,flexibility,open-door policy,training,and motivation.Consequences impacting the success of reflective supervision were identified as promotion of resiliency,autonomy,work-life balance,self-awareness,increased self-esteem,professional development,critical thinking,increased job satisfaction,and enhanced commitment.Conclusions Reflective supervision is a complex professional self-care strategy that enhances ICU practice,by promoting nurses’well-being,self-awareness,therapeutic skills,and professional development.展开更多
Urban rainwater runoff is an important source of nonpoint source pollution due to its transport of diverse contaminants,including polycyclic aromatic hydrocarbons(PAHs)and chlorinated derivatives.Importantly,these chl...Urban rainwater runoff is an important source of nonpoint source pollution due to its transport of diverse contaminants,including polycyclic aromatic hydrocarbons(PAHs)and chlorinated derivatives.Importantly,these chlorinated polycyclic aromatic hydrocarbons(Cl-PAHs)exhibit elevated toxicological potential compared to their non-halogenated parent compounds.In this study,we proposed an approach that combined multivariate receptor model with integration of SHapley Additive exPlanations and Random Forest model.This method identifies the possible sources and reveals the impact of source apportionment results and environmental driving factors(such as geographical and meteorological data)on pollutant concentrations.Sixteen PAHs and nine ClPAHs were detected in 79 runoff samples from all three sites.TheΣ_(16)PAHs average concentration(2923.93 to 6071.83 ng/L)was significantly higher than theΣ_(9)Cl-PAHs(384.34 to 1314.73 ng/L).The source apportionment was conducted by positive matrix factorization(PMF),and six potential pollution sources for PAHs and three for Cl-PAHs were quantified.PAHs primarily originate from the combustion of fossil fuels such as traffic,industrial emissions and coal tar,while Cl-PAHs are mainly derived from atmospheric deposition and industrial emissions.Meanwhile,the self‑organizing map classified PAHs and Cl-PAHs into 2 and 3 groups,respectively.The k-means algorithm yielded 4 clusters for runoff samples.Among machine learning models,Random Forest(RF)demonstrated optimal predictive performance and integrated with SHapley Additive exPlanations(RF-SHAP)revealed the effects of driving factors on the predicted concentration of PAHs and Cl-PAHs in urban runoff samples.展开更多
This paper focuses on the leader-following positive consensus problems of heterogeneous switched multi-agent systems.First,a state-feedback controller with dynamic compensation is introduced to achieve positive consen...This paper focuses on the leader-following positive consensus problems of heterogeneous switched multi-agent systems.First,a state-feedback controller with dynamic compensation is introduced to achieve positive consensus under average dwell time switching.Then sufficient conditions are derived to guarantee the positive consensus.The gain matrices of the control protocol are described using a matrix decomposition approach and the corresponding computational complexity is reduced by resorting to linear programming and co-positive Lyapunov functions.Finally,two numerical examples are provided to illustrate the results obtained.展开更多
The performance of lithium-sulfur batteries(LSBs)is severely limited by a detrimental negative feedback loop:sluggish polysulfide conversion kinetics lead to Li_(2)S accumulation,which further hinders lithiumion trans...The performance of lithium-sulfur batteries(LSBs)is severely limited by a detrimental negative feedback loop:sluggish polysulfide conversion kinetics lead to Li_(2)S accumulation,which further hinders lithiumion transport and exacerbates capacity decay.To address this,we propose a positive feedback strategy that simultaneously enhances lithium polysulfides(LiPSs)conversion and lithium-ion diffusion through a rationally designed separator.By modifying the separator with phosphorus-doped two-dimensional hollow holey carbon nanosheets(Hollow HCNS),we establish an interconnected network where rapid LiPSs confinement and conversion within the hollow cavities promote efficient lithium-ion transport,while the improved ion flux further accelerates reaction kinetics.This mutual reinforcement mechanism ensures stable cycling by suppressing the shuttle effect and promoting uniform Li_(2)S deposition,as verified by in situ spectroscopic and electrochemical analysis.The resulting LSBs exhibit high-rate capability,ultralow capacity decay,and exceptional stability under high sulfur loading.This work presents a general approach to overcoming the persistent negative feedback problem in high-energy battery systems by synergistically optimizing catalytic conversion and ionic transport.展开更多
Objective: To evaluate the efficacy of noninvasive positive pressure ventilation (NIPPV) in respiratory support for severe pneumonia. Methods: Data were analyzed from 74 patients with severe pneumonia undergoing respi...Objective: To evaluate the efficacy of noninvasive positive pressure ventilation (NIPPV) in respiratory support for severe pneumonia. Methods: Data were analyzed from 74 patients with severe pneumonia undergoing respiratory support at our hospital between May 2024 and April 2025. Patients were randomly assigned using a random number table to two groups (n = 37 each): the experimental group received NIPPV, while the control group underwent conventional invasive mechanical ventilation. Intergroup differences were compared. Results: Compared with the control group, the experimental group demonstrated significantly higher PaO2 and oxygenation index, significantly lower PaCO2, significantly reduced levels of WBC, CRP, and PCT, significantly higher overall efficacy rate, and significantly lower incidence of adverse reactions after treatment (p < 0.05). Pre-treatment PaO2, oxygenation index, PaCO2, WBC, CRP, and PCT levels showed no significant differences between groups (p > 0.05). Conclusion: Non-invasive positive pressure ventilation demonstrates favorable outcomes in respiratory support for severe pneumonia.展开更多
Background:Emerging adulthood is a critical period for ego identity exploration and consolidation,and self-presentation on social media constitutes a salient online context for this developmental process.However,limit...Background:Emerging adulthood is a critical period for ego identity exploration and consolidation,and self-presentation on social media constitutes a salient online context for this developmental process.However,limited research has explored the associations between self-presentation on WeChat Moments and ego identity.This study aims to examine these associations,focusing on the mediating role of online positive feedback and the moderating role of gender.Methods:Using a three-wave longitudinal design,this study followed 767 Chinese college students(Mean age=18.96 years)through cluster sampling.Participants completed self-report questionnaires assessing self-presentation on WeChat Moments,online positive feedback,and ego identity status.Data analyses were conducted using mediation modeling and multi-group structural equation modeling.Results:Authentic self-presentation was positively associated with identity achievement and negatively associated with identity diffusion,whereas positive self-presentation was linked to higher levels of identity foreclosure.Online positive feedback played a significant mediating role in the associations between self-presentation strategies and identity statuses,and gender differences were observed in this mediating pathway.For both males and females,authentic self-presentation was associated with higher identity achievement through online positive feedback.However,indirect associations with identity foreclosure and diffusion were observed only among females:authentic self-presentation was linked to lower levels,whereas positive self-presentation was linked to higher levels of foreclosure and diffusion through online positive feedback.No comparable indirect associations were detected among males.Conclusions:Online positive feedback is closely linked to self-presentation strategies and ego identity statuses,with these associations varying by gender.展开更多
Let M be a compact n-manifold of positive sectional curvature.We will review classical results on the fundamental group of M,a motivation on the c(n)-cyclic conjecture that the fundamental group of M contains a cyclic...Let M be a compact n-manifold of positive sectional curvature.We will review classical results on the fundamental group of M,a motivation on the c(n)-cyclic conjecture that the fundamental group of M contains a cyclic subgroup of index bounded above by c(n),a constant depending only on n,and we will survey partial results(up to date)on the c(n)-cyclic conjecture.展开更多
As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting ...As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting billets,and production efficiency.Al_(2)O_(3) inclusions clogging constitutes the predominant failure mode of SEN,particularly during continuous casting of high-grade steels.Although several studies in the literature have demonstrated that electric field application can mitigate SEN clogging to some extent,the underlying mechanism remains poorly understood,which hinders its widespread acceptance and practical implementation.The mechanism of preventing SEN clogging by applying a positive electric field was studied,and experimental verification was conducted on it in a certain steel plant.The results indicate that Al_(2)O_(3) inclusions exhibit a positive charge in molten steel under high-temperature(~1600℃)and low-oxygen-partial-pressure(≤20×10-6)conditions.In the continuous casting process at a Chinese steel plant,applying a positive electric field to the SEN effectively suppressed the migration of Al_(2)O_(3) inclusions toward the SEN wall,significantly enhancing its clogging resistance.展开更多
基金supported by the National Institute of Environmental Research(NIER)funded by the Ministry of Environment(No.NIER-2019-04-02-039)supported by Particulate Matter Management Specialized Graduate Program through the Korea Environmental Industry&Technology Institute(KEITI)funded by the Ministry of Environment(MOE).
文摘Fine particulatematter(PM_(2.5))samples were collected in two neighboring cities,Beijing and Baoding,China.High-concentration events of PM_(2.5) in which the average mass concentration exceeded 75μg/m^(3) were frequently observed during the heating season.Dispersion Normalized Positive Matrix Factorization was applied for the source apportionment of PM_(2.5) as minimize the dilution effects of meteorology and better reflect the source strengths in these two cities.Secondary nitrate had the highest contribution for Beijing(37.3%),and residential heating/biomass burning was the largest for Baoding(27.1%).Secondary nitrate,mobile,biomass burning,district heating,oil combustion,aged sea salt sources showed significant differences between the heating and non-heating seasons in Beijing for same period(2019.01.10–2019.08.22)(Mann-Whitney Rank Sum Test P<0.05).In case of Baoding,soil,residential heating/biomass burning,incinerator,coal combustion,oil combustion sources showed significant differences.The results of Pearson correlation analysis for the common sources between the two cities showed that long-range transported sources and some sources with seasonal patterns such as oil combustion and soil had high correlation coefficients.Conditional Bivariate Probability Function(CBPF)was used to identify the inflow directions for the sources,and joint-PSCF(Potential Source Contribution Function)was performed to determine the common potential source areas for sources affecting both cities.These models facilitated a more precise verification of city-specific influences on PM_(2.5) sources.The results of this study will aid in prioritizing air pollution mitigation strategies during the heating season and strengthening air quality management to reduce the impact of downwind neighboring cities.
基金supported by the 2024 Zhejiang Provincial Women’s Federation&Women’s Studies Association Research Project(202450).
文摘Objective:International students frequently face psychological adaptation difficulties while studying and living abroad.As an effective psychological resource,positive solitude has been identified as a potential factor for improving psychological well-being,but the underlying mechanism linking the two has not been fully explored.The current study aims to explore the relationship between positive solitude and psychological adaptation of international students,with particular emphasis on the intermediary roles of authenticity and loneliness.Methods:A total of 529 international tertiary students(Mage=23.76,SD=5.08;60.68%male)were surveyed using the Positive Solitude Scale(PSS),Authenticity Scale(AS),6-item UCLA Loneliness Scale(ULS-6),and Brief Psychological Adaptation Scale(BPAS).SPSS27.0 was used for descriptive statistical analysis and Pearson correlation analysis.PROCESS macro(Model 6)was employed to test a serial mediation model,in which authenticity and loneliness function as intermediary variables between positive solitude and psychological adaptation.Results:The correlation analysis indicated significant associations among positive solitude,authenticity,loneliness,and psychological adaptation(r=−0.544~0.511).Positive solitude was directly and positively related to psychological adaptation(β=0.132,t=3.609,p<0.001)and indirectly related to psychological adaptation through two pathways:a single mediation via authenticity(indirect effect=0.089)and a serial mediation through authenticity and loneliness(indirect effect=0.062).Loneliness did not serve as a significant mediator(indirect effect=–0.015,95%CI[–0.049,0.019]).The total indirect effect was 0.136.Conclusions:Interventions targeting international students’capacity for experiencing positive solitude and authenticity can help to reduce loneliness and increase psychological adaptation.The findings derived from this study are conducive to understanding the relationship between positive solitude and psychological adaptation,as well as its underlying mechanisms.In addition,the study offers a new perspective for educational management and psychological counseling services for international students.
基金Supported by Scientific Research Project of Jilin Provincial Department of Education(JJKH20250464KJ)。
文摘This paper deals with homogeneous Dirichlet boundary value problem to a class of porous medium equations with viscoelastic term ∂u/∂t-Δu^(m)+∫^(t)_(0)g(t-s)Δu^(m)(x,s)ds=u^(p),x∈Ω,t≥0,where p>m(m>0).We prove that the weak solutions of the above problem blow up in finite time when the initial energy is positive and the function g satisfies suitable conditions.Our result generalizes that of S.A.Messaoudi in[1].
文摘Objectives This study aimed to explore and clarify the concept of reflective supervision as a professional self-care strategy to create a positive Intensive Care Unit(ICU)practice environment.Methods Walker and Avant’s eight-step concept analysis approach was utilized to identify and define the attributes,antecedents,and consequences of reflective supervision in the ICU.An extensive literature search was conducted across various databases,including Google Scholar,CINAHL,PubMed.Articles published from 2005 to 2025 were identified.We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)2020 statement to indicate the included articles and extract related data based on relevance.Results Forty articles were included in the analysis.The identified attributes included the supervisor-supervisee relationship,effective communication,teamwork,collaborations,reflection,competencies,feedback,continuous support,and autonomous choice.The identified antecedents included participation,supportive supervision,flexibility,open-door policy,training,and motivation.Consequences impacting the success of reflective supervision were identified as promotion of resiliency,autonomy,work-life balance,self-awareness,increased self-esteem,professional development,critical thinking,increased job satisfaction,and enhanced commitment.Conclusions Reflective supervision is a complex professional self-care strategy that enhances ICU practice,by promoting nurses’well-being,self-awareness,therapeutic skills,and professional development.
基金supported by Guangdong Basic and Applied Basic Research Foundation(Nos.2021B1515120055 and 2022A1515010499).
文摘Urban rainwater runoff is an important source of nonpoint source pollution due to its transport of diverse contaminants,including polycyclic aromatic hydrocarbons(PAHs)and chlorinated derivatives.Importantly,these chlorinated polycyclic aromatic hydrocarbons(Cl-PAHs)exhibit elevated toxicological potential compared to their non-halogenated parent compounds.In this study,we proposed an approach that combined multivariate receptor model with integration of SHapley Additive exPlanations and Random Forest model.This method identifies the possible sources and reveals the impact of source apportionment results and environmental driving factors(such as geographical and meteorological data)on pollutant concentrations.Sixteen PAHs and nine ClPAHs were detected in 79 runoff samples from all three sites.TheΣ_(16)PAHs average concentration(2923.93 to 6071.83 ng/L)was significantly higher than theΣ_(9)Cl-PAHs(384.34 to 1314.73 ng/L).The source apportionment was conducted by positive matrix factorization(PMF),and six potential pollution sources for PAHs and three for Cl-PAHs were quantified.PAHs primarily originate from the combustion of fossil fuels such as traffic,industrial emissions and coal tar,while Cl-PAHs are mainly derived from atmospheric deposition and industrial emissions.Meanwhile,the self‑organizing map classified PAHs and Cl-PAHs into 2 and 3 groups,respectively.The k-means algorithm yielded 4 clusters for runoff samples.Among machine learning models,Random Forest(RF)demonstrated optimal predictive performance and integrated with SHapley Additive exPlanations(RF-SHAP)revealed the effects of driving factors on the predicted concentration of PAHs and Cl-PAHs in urban runoff samples.
基金supported by the National Natural Science Foundation of China(62463007,62463005)the Natural Science Foundation of Hainan Province(625RC710,625MS047)+1 种基金the System Control and Information Processing Education Ministry Key Laboratory Open Funding,China(Scip20240119)the Science Research Funding of Hainan University,China(KYQD(ZR)22180,KYQD(ZR)23180).
文摘This paper focuses on the leader-following positive consensus problems of heterogeneous switched multi-agent systems.First,a state-feedback controller with dynamic compensation is introduced to achieve positive consensus under average dwell time switching.Then sufficient conditions are derived to guarantee the positive consensus.The gain matrices of the control protocol are described using a matrix decomposition approach and the corresponding computational complexity is reduced by resorting to linear programming and co-positive Lyapunov functions.Finally,two numerical examples are provided to illustrate the results obtained.
基金the support from the National Science Foundation of China(22471226,22272142)the 111 Project(B16029)。
文摘The performance of lithium-sulfur batteries(LSBs)is severely limited by a detrimental negative feedback loop:sluggish polysulfide conversion kinetics lead to Li_(2)S accumulation,which further hinders lithiumion transport and exacerbates capacity decay.To address this,we propose a positive feedback strategy that simultaneously enhances lithium polysulfides(LiPSs)conversion and lithium-ion diffusion through a rationally designed separator.By modifying the separator with phosphorus-doped two-dimensional hollow holey carbon nanosheets(Hollow HCNS),we establish an interconnected network where rapid LiPSs confinement and conversion within the hollow cavities promote efficient lithium-ion transport,while the improved ion flux further accelerates reaction kinetics.This mutual reinforcement mechanism ensures stable cycling by suppressing the shuttle effect and promoting uniform Li_(2)S deposition,as verified by in situ spectroscopic and electrochemical analysis.The resulting LSBs exhibit high-rate capability,ultralow capacity decay,and exceptional stability under high sulfur loading.This work presents a general approach to overcoming the persistent negative feedback problem in high-energy battery systems by synergistically optimizing catalytic conversion and ionic transport.
文摘Objective: To evaluate the efficacy of noninvasive positive pressure ventilation (NIPPV) in respiratory support for severe pneumonia. Methods: Data were analyzed from 74 patients with severe pneumonia undergoing respiratory support at our hospital between May 2024 and April 2025. Patients were randomly assigned using a random number table to two groups (n = 37 each): the experimental group received NIPPV, while the control group underwent conventional invasive mechanical ventilation. Intergroup differences were compared. Results: Compared with the control group, the experimental group demonstrated significantly higher PaO2 and oxygenation index, significantly lower PaCO2, significantly reduced levels of WBC, CRP, and PCT, significantly higher overall efficacy rate, and significantly lower incidence of adverse reactions after treatment (p < 0.05). Pre-treatment PaO2, oxygenation index, PaCO2, WBC, CRP, and PCT levels showed no significant differences between groups (p > 0.05). Conclusion: Non-invasive positive pressure ventilation demonstrates favorable outcomes in respiratory support for severe pneumonia.
基金supported by the National Social Science Fund of China(No.23BSH123).
文摘Background:Emerging adulthood is a critical period for ego identity exploration and consolidation,and self-presentation on social media constitutes a salient online context for this developmental process.However,limited research has explored the associations between self-presentation on WeChat Moments and ego identity.This study aims to examine these associations,focusing on the mediating role of online positive feedback and the moderating role of gender.Methods:Using a three-wave longitudinal design,this study followed 767 Chinese college students(Mean age=18.96 years)through cluster sampling.Participants completed self-report questionnaires assessing self-presentation on WeChat Moments,online positive feedback,and ego identity status.Data analyses were conducted using mediation modeling and multi-group structural equation modeling.Results:Authentic self-presentation was positively associated with identity achievement and negatively associated with identity diffusion,whereas positive self-presentation was linked to higher levels of identity foreclosure.Online positive feedback played a significant mediating role in the associations between self-presentation strategies and identity statuses,and gender differences were observed in this mediating pathway.For both males and females,authentic self-presentation was associated with higher identity achievement through online positive feedback.However,indirect associations with identity foreclosure and diffusion were observed only among females:authentic self-presentation was linked to lower levels,whereas positive self-presentation was linked to higher levels of foreclosure and diffusion through online positive feedback.No comparable indirect associations were detected among males.Conclusions:Online positive feedback is closely linked to self-presentation strategies and ego identity statuses,with these associations varying by gender.
文摘Let M be a compact n-manifold of positive sectional curvature.We will review classical results on the fundamental group of M,a motivation on the c(n)-cyclic conjecture that the fundamental group of M contains a cyclic subgroup of index bounded above by c(n),a constant depending only on n,and we will survey partial results(up to date)on the c(n)-cyclic conjecture.
基金supported by the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(No.52302031)National Natural Science Foundation of China(No.51932008).
文摘As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting billets,and production efficiency.Al_(2)O_(3) inclusions clogging constitutes the predominant failure mode of SEN,particularly during continuous casting of high-grade steels.Although several studies in the literature have demonstrated that electric field application can mitigate SEN clogging to some extent,the underlying mechanism remains poorly understood,which hinders its widespread acceptance and practical implementation.The mechanism of preventing SEN clogging by applying a positive electric field was studied,and experimental verification was conducted on it in a certain steel plant.The results indicate that Al_(2)O_(3) inclusions exhibit a positive charge in molten steel under high-temperature(~1600℃)and low-oxygen-partial-pressure(≤20×10-6)conditions.In the continuous casting process at a Chinese steel plant,applying a positive electric field to the SEN effectively suppressed the migration of Al_(2)O_(3) inclusions toward the SEN wall,significantly enhancing its clogging resistance.
