Dear Editor,This letter investigates predefined-time optimization problems(OPs) of multi-agent systems(MASs), where the agent of MASs is subject to inequality constraints, and the team objective function accounts for ...Dear Editor,This letter investigates predefined-time optimization problems(OPs) of multi-agent systems(MASs), where the agent of MASs is subject to inequality constraints, and the team objective function accounts for impulse effects. Firstly, to address the inequality constraints,the penalty method is introduced. Then, a novel optimization strategy is developed, which only requires that the team objective function be strongly convex.展开更多
Dear Editor,This letter studies a real-world issue in leader-follower multi-agent systems(MASs)named open topology,which permits the variations of agent set and network connections.Specially,a novel transition process...Dear Editor,This letter studies a real-world issue in leader-follower multi-agent systems(MASs)named open topology,which permits the variations of agent set and network connections.Specially,a novel transition process is developed to explain how the involved variation of network scale affects the dynamic behavior of the MASs.From a resource limited perspective,the distributed saturated impulsive control is then designed,under which some sufficient criteria are integrated into local quasi-consensus performance.We also provide a combined optimization algorithm for all agents to make the estimated domain of initial errors closer to the real one,thereby resulting in less conservativeness.Finally,a numerical example validates our results.展开更多
Density-functional-theory(DFT)simulations with the Vienna Ab initio Simulation Package(VASP)are indispensable in computational materials science but often require extensive manual setup,monitoring,and postprocessing.H...Density-functional-theory(DFT)simulations with the Vienna Ab initio Simulation Package(VASP)are indispensable in computational materials science but often require extensive manual setup,monitoring,and postprocessing.Here,we introduce VASPilot,an open-source platform that fully automates VASP workflows via a multi-agent architecture built on the CrewAI framework and a standardized model context protocol(MCP).VASPilot’s agent suite handles every stage of a VASP study from retrieving crystal structures and generating input files to submitting Slurm jobs,parsing error messages,and dynamically adjusting parameters for seamless restarts.A lightweight Quart-based web interface provides intuitive task submission,real-time progress tracking,and drill-down access to execution logs,structure visualizations,and plots.We validated VASPilot on both routine and advanced benchmarks:automated band-structure and density-of-states calculations(including on-the-fly symmetry corrections),plane-wave cutoff convergence tests,lattice-constant optimizations with various van der Waals corrections,and cross-material band-gap comparisons for transition-metal dichalcogenides.In all cases,VASPilot completed the missions reliably and without manual intervention.Moreover,its modular design allows easy extension to other DFT codes simply by deploying the appropriate MCP server.By offloading technical overhead,VASPilot enables researchers to focus on scientific discovery and accelerates high-throughput computational materials research.展开更多
Multi-agent systems often require good interoperability in the process of completing their assigned tasks.This paper first models the static structure and dynamic behavior of multiagent systems based on layered weight...Multi-agent systems often require good interoperability in the process of completing their assigned tasks.This paper first models the static structure and dynamic behavior of multiagent systems based on layered weighted scale-free community network and susceptible-infected-recovered(SIR)model.To solve the problem of difficulty in describing the changes in the structure and collaboration mode of the system under external factors,a two-dimensional Monte Carlo method and an improved dynamic Bayesian network are used to simulate the impact of external environmental factors on multi-agent systems.A collaborative information flow path optimization algorithm for agents under environmental factors is designed based on the Dijkstra algorithm.A method for evaluating system interoperability is designed based on simulation experiments,providing reference for the construction planning and optimization of organizational application of the system.Finally,the feasibility of the method is verified through case studies.展开更多
Plants have long served as a cornerstone for drug discovery,offering a vast repertoire of bioactive compounds with proven efficacy in combating oxidative stress,a pivotal driver of chronic diseases such as cancer,diab...Plants have long served as a cornerstone for drug discovery,offering a vast repertoire of bioactive compounds with proven efficacy in combating oxidative stress,a pivotal driver of chronic diseases such as cancer,diabetes,cardiovascular disorders,and neurodegenerative conditions.This review synthesizes current knowledge on plant-derived antioxidants,emphasizing their mechanisms,therapeutic potential,and quantitative efficacy validated through standardized assays.Key phytochemicals,including polyphenols,carotenoids,flavonoids,and terpenoids,neutralize reactive oxygen species(ROS)through radical scavenging,enzyme modulation,and gene regulation.For instance,lutein,a carotenoid found in leafy greens,demonstrates potent antioxidant activity with IC50 values of 1.75μg/mL against hydroxyl radicals and 2.2μg/mL in lipid peroxidation inhibition,underscoring its role in mitigating cardiovascular and ocular diseases.Similarly,quercetin,a ubiquitous flavonoid in onions and berries,exhibits remarkable ROS-scavenging capacity,with IC50 values of 0.55μg/mL,2,2-Diphenyl-1-picrylhydrazyl(DPPH)and 1.17μg/mL,2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS),supporting its use in reducing inflammation and neurodegeneration.The therapeutic promise of these compounds extends to disease-specific applications.Limonoids from citrus fruits,such as limonin(IC_(50)15-31μg/mL),enhance Phase II detoxification enzymes,offering protection against chemical carcinogens.Sulforaphane,a glucosinolate derived from cruciferous vegetables,shows potent anticancer activity with an IC50 of 85.66 mg in DPPH radical scavenging,whileβ-sitosterol(IC_(50)1.43-2.42 mM)inhibits tumor proliferation and cholesterol synthesis.Synergistic interactions further amplify their efficacy:phytoestrogens like genistein(IC_(50)13.00 ppm)and terpenoids such asα-pinene(IC_(50)12.57 mg/mL)collectively enhance antiinflammatory and antimicrobial responses,illustrating the multi-targeted nature of plant-based therapies.Beyond disease prevention,these compounds address age-related decline.Ascorbic acid(vitamin C),with an IC50 of 11.81μg/mL for antioxidant activity,mitigates skin aging and accelerates wound healing,while seleniumnanoparticles(IC_(50)0.437μg/mL)bolster immune function and reduce chemotherapy-induced toxicity.Dietary fibers,exemplified by sugar beet fibers(IC_(50)52.32μg/mL for DPPH scavenging),further contribute to cardiovascular health by lowering Low-Density Lipoprotein(LDL)cholesterol.This review not only catalogs the antioxidant prowess of phytochemicals but also highlights their translational potential.Advances in nanotechnology,such as nano-formulated curcumin,have overcome bioavailability challenges,enhancing clinical applicability.By integrating quantitative metrics(e.g.,IC50,radical scavenging rates)with mechanistic insights,this work bridges the gap between traditional knowledge and modern pharmacology.展开更多
Dear Editor,This letter is concerned with the problem of time-varying formation tracking for heterogeneous multi-agent systems(MASs) under directed switching networks. For this purpose, our first step is to present so...Dear Editor,This letter is concerned with the problem of time-varying formation tracking for heterogeneous multi-agent systems(MASs) under directed switching networks. For this purpose, our first step is to present some sufficient conditions for the exponential stability of a particular category of switched systems.展开更多
AI Agent技术凭借环境感知、自主决策与协同执行能力,为财务共享服务中心的智能化升级提供了新型技术方案。财务共享中心作为集约化财务管理载体,在业务规模扩张与数据量激增的背景下,面临着风险识别滞后与资金结算效率不足等挑战,AI Ag...AI Agent技术凭借环境感知、自主决策与协同执行能力,为财务共享服务中心的智能化升级提供了新型技术方案。财务共享中心作为集约化财务管理载体,在业务规模扩张与数据量激增的背景下,面临着风险识别滞后与资金结算效率不足等挑战,AI Agent通过构建智能识别预警系统、动态评估管控体系、自动化应急处置机制及全程追踪管理框架,实现了交易异常、信用风险、资金异常与合规风险的精准防控。展开更多
Artificial intelligence(AI)is reshaping financial systems and services,as intelligent AI agents increasingly form the foundation of autonomous,goal-driven systems capable of reasoning,learning,and action.This review s...Artificial intelligence(AI)is reshaping financial systems and services,as intelligent AI agents increasingly form the foundation of autonomous,goal-driven systems capable of reasoning,learning,and action.This review synthesizes recent research and developments in the application of AI agents across core financial domains.Specifically,it covers the deployment of agent-based AI in algorithmic trading,fraud detection,credit risk assessment,roboadvisory,and regulatory compliance(RegTech).The review focuses on advanced agent-based methodologies,including reinforcement learning,multi-agent systems,and autonomous decision-making frameworks,particularly those leveraging large language models(LLMs),contrasting these with traditional AI or purely statistical models.Our primary goals are to consolidate current knowledge,identify significant trends and architectural approaches,review the practical efficiency and impact of current applications,and delineate key challenges and promising future research directions.The increasing sophistication of AI agents offers unprecedented opportunities for innovation in finance,yet presents complex technical,ethical,and regulatory challenges that demand careful consideration and proactive strategies.This review aims to provide a comprehensive understanding of this rapidly evolving landscape,highlighting the role of agent-based AI in the ongoing transformation of the financial industry,and is intended to serve financial institutions,regulators,investors,analysts,researchers,and other key stakeholders in the financial ecosystem.展开更多
Dear Editor,This letter studies the bipartite consensus tracking problem for heterogeneous multi-agent systems with actuator faults and a leader's unknown time-varying control input. To handle such a problem, the ...Dear Editor,This letter studies the bipartite consensus tracking problem for heterogeneous multi-agent systems with actuator faults and a leader's unknown time-varying control input. To handle such a problem, the continuous fault-tolerant control protocol via observer design is developed. In addition, it is strictly proved that the multi-agent system driven by the designed controllers can still achieve bipartite consensus tracking after faults occur.展开更多
Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,...Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,the migration behavior of temporary plugging agent(TPA),as a function of the concentration and particle size of TPA and cluster-perforation numbers,etc.,determining the effectiveness of this technique,remains unclear.Therefore,this study conducted innovatively a series of TPDF simulation experiments on transparent polymethyl methacrylate(PMMA)specimens(cubic block of 30 cm×30 cm×30 cm)to explore visually the migration behavior of TPA in multi-clustered HFs in a horizontal well.A laboratory hydraulic sandblasting perforation completion technique was implemented to simulate the multi-cluster perforations.All the distributions of wellbore,perforations,HFs,and TPA can be seen clearly inside the PMMA specimen post the experiment.The results show that there are four characteristic plugging positions for the TPA:mouth of HF,middle of HF,tip of HF,and the intersection of HFs.Small particle size TPA tends to migrate to the fracture tip for plugging,while large particle size TPA tends to plug at the fracture mouth.The migration of the TPA is influenced obviously by the morphology of the fracture wall.A smooth fracture wall is conducive to the migration of the TPA to the far end of HFs,but not conducive to generating the plugging zone and HF diversion.In contrast,a"leaf vein"fracture of rough wall is conducive to generating the plugging layer and the diversion of HFs,but not conducive to the migration of the TPA to the far end of HFs.The migration ability of TPA in a"shell"pattern is intermediate between the two above cases.Increasing TPA concentration can encourage TPA to migrate more quickly to the characteristic plugging position,and thereby to promote the creation of effective plugging and subsequently the multi-stage diversion of the HFs.Nevertheless,excessive concentration may cause the TPA to settle prematurely,affecting the propagation of the HFs to the far end.Increasing the number of clusters to a certain extent can encourage TPA to migrate into the HFs and form plugging,and promote the diversion.An evaluation system for the migration ability of granular TPA has been established,and it was calculated that when there is no plugging expectation target,the comprehensive migration ability of small particle size TPA is stronger than that of large particle size TPA.This research provides theoretical foundation for the optimization of temporary plugging parameters.展开更多
The chemical structure of polyamide 6(PA6)dictates that only 50%of hydrogen bonds participate in crystallization during the crystallization process,resulting in the properties of its products being significantly depen...The chemical structure of polyamide 6(PA6)dictates that only 50%of hydrogen bonds participate in crystallization during the crystallization process,resulting in the properties of its products being significantly dependent on the molding process.Therefore,the design and development of nucleating agents suitable for PA6 holds great practical significance for high-performance PA6 materials.Amide-based nucleating agents can effectively improve the crystallization rate by increasing intermolecular hydrogen bond density.Further introduction of hydroxyl groups can enhance the hydrogen bonding interactions between the nucleating agent and PA6.In this study,a hydroxyl-containing amidebased nucleating agent,BHT,was designed and synthesized using a tyramine-based biomass as the raw material.These results demonstrated that BHT exhibited good structural compatibility with PA6.After adding 1 wt%BHT,the crystallization temperature of PA6 increased from 170.9℃to 193.3℃,the crystallinity increased 16.6%,the heat distortion temperature and Vicat softening temperature rose to 89.5 and 187.8℃,respectively,the haze decreased to 46%,achieving the synergistic optimization of mechanical,thermal,and optical properties.The in situ time-resolved FTIR results indicated that the addition of BHT increased the enthalpy of hydrogen bond formation during the nucleation stage,facilitated the segmental conformation adjustment of PA6,and enhanced the molar concentration of trans-conformations,ultimately leading to an improvement in the crystallization rate.展开更多
The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light...The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light absorption to charge separation,transport,and ultimately charge collection.Dynamic changes in crystallization and aggregation states can also disrupt the microstructure of the active layer,thus shortening the lifetime of the cell.In this study,a morphology modulation strategy is proposed to regulate the crystallization kinetics of non-fullerene acceptors by employing the polymer molecule PYIT as a nucleating agent.An appropriate amount of PYIT was first completely dissolved with the non-fullerene acceptor Y6 and left to stand for 24 h,followed by the fabrication of layer-by-layer processed OSCs.Experiments demonstrated that high crystallinity of PYIT allows it to act as a crystallization nucleus,promoting the crystallization,orientation consistency,and ordered stacking of the acceptor.These nanoscale structural optimizations facilitate efficient charge transport,enhance exciton dissociation efficiency,and suppress unfavorable energetic disorder.Consequently,not only was the power conversion efficiency(PCE)of D18-Cl/Y6-based layer-by-layer processed OSC increased from 18.08%to 19.13%,but the atmospheric stability and long-term lifetime of the OSCs were also significantly improved.Notably,this strategy is also applicable to indoor OSCs,and the PYIT-optimized device can achieve a PCE of 27.0%under 1000 lux light-emitting diode(LED,3200K)irradiation,which is superior to that of the control device(24.2%).This work develops a crystal engineering strategy that is able to simultaneously optimize the microscopic morphology and charge dynamics properties in OSCs,thereby achieving simultaneous improvement in efficiency and stability.展开更多
基金supported in part by the National Natural Science Foundation of China(62276119)the Natural Science Foundation of Jiangsu Province(BK20241764)the Postgraduate Research & Practice Innovation Program of Jiangsu Province(KYCX22_2860)
文摘Dear Editor,This letter investigates predefined-time optimization problems(OPs) of multi-agent systems(MASs), where the agent of MASs is subject to inequality constraints, and the team objective function accounts for impulse effects. Firstly, to address the inequality constraints,the penalty method is introduced. Then, a novel optimization strategy is developed, which only requires that the team objective function be strongly convex.
基金supported by the Natural Science Foundation of Jiangsu Province(BK20240009)the National Natural Science Foundation of China(62373105,62373262)Jiangsu Provincial Scientific Research Center of Applied Mathematics(BK20233002).
文摘Dear Editor,This letter studies a real-world issue in leader-follower multi-agent systems(MASs)named open topology,which permits the variations of agent set and network connections.Specially,a novel transition process is developed to explain how the involved variation of network scale affects the dynamic behavior of the MASs.From a resource limited perspective,the distributed saturated impulsive control is then designed,under which some sufficient criteria are integrated into local quasi-consensus performance.We also provide a combined optimization algorithm for all agents to make the estimated domain of initial errors closer to the real one,thereby resulting in less conservativeness.Finally,a numerical example validates our results.
基金supported by the Science Center of the National Natural Science Foundation of China(Grant No.12188101)the National Key R&D Program of China(Grant Nos.2023YFA1607400 and 2022YFA1403800)+2 种基金the National Natural Science Foundation of China(Grant Nos.12274436,11925408,and 11921004)the New Cornerstone Science Foundation through the XPLORER PRIZEperformed on the robotic AI-Scientist platform of the Chinese Academy of Science.
文摘Density-functional-theory(DFT)simulations with the Vienna Ab initio Simulation Package(VASP)are indispensable in computational materials science but often require extensive manual setup,monitoring,and postprocessing.Here,we introduce VASPilot,an open-source platform that fully automates VASP workflows via a multi-agent architecture built on the CrewAI framework and a standardized model context protocol(MCP).VASPilot’s agent suite handles every stage of a VASP study from retrieving crystal structures and generating input files to submitting Slurm jobs,parsing error messages,and dynamically adjusting parameters for seamless restarts.A lightweight Quart-based web interface provides intuitive task submission,real-time progress tracking,and drill-down access to execution logs,structure visualizations,and plots.We validated VASPilot on both routine and advanced benchmarks:automated band-structure and density-of-states calculations(including on-the-fly symmetry corrections),plane-wave cutoff convergence tests,lattice-constant optimizations with various van der Waals corrections,and cross-material band-gap comparisons for transition-metal dichalcogenides.In all cases,VASPilot completed the missions reliably and without manual intervention.Moreover,its modular design allows easy extension to other DFT codes simply by deploying the appropriate MCP server.By offloading technical overhead,VASPilot enables researchers to focus on scientific discovery and accelerates high-throughput computational materials research.
基金supported by the Key R&D Projects in Jiangsu Province(BE2021729)the Key Primary Research Project of Primary Strengthening Program(KYZYJKKCJC23001).
文摘Multi-agent systems often require good interoperability in the process of completing their assigned tasks.This paper first models the static structure and dynamic behavior of multiagent systems based on layered weighted scale-free community network and susceptible-infected-recovered(SIR)model.To solve the problem of difficulty in describing the changes in the structure and collaboration mode of the system under external factors,a two-dimensional Monte Carlo method and an improved dynamic Bayesian network are used to simulate the impact of external environmental factors on multi-agent systems.A collaborative information flow path optimization algorithm for agents under environmental factors is designed based on the Dijkstra algorithm.A method for evaluating system interoperability is designed based on simulation experiments,providing reference for the construction planning and optimization of organizational application of the system.Finally,the feasibility of the method is verified through case studies.
基金funded by the project of Scientific Research Start-up Funds for Doctoral Talents of Zhaotong University-Mingzheng Duan,Grant number:202406Young Talent Project of Talent Support Program for the Development of Yunnan,Grant number:210604199008271015.
文摘Plants have long served as a cornerstone for drug discovery,offering a vast repertoire of bioactive compounds with proven efficacy in combating oxidative stress,a pivotal driver of chronic diseases such as cancer,diabetes,cardiovascular disorders,and neurodegenerative conditions.This review synthesizes current knowledge on plant-derived antioxidants,emphasizing their mechanisms,therapeutic potential,and quantitative efficacy validated through standardized assays.Key phytochemicals,including polyphenols,carotenoids,flavonoids,and terpenoids,neutralize reactive oxygen species(ROS)through radical scavenging,enzyme modulation,and gene regulation.For instance,lutein,a carotenoid found in leafy greens,demonstrates potent antioxidant activity with IC50 values of 1.75μg/mL against hydroxyl radicals and 2.2μg/mL in lipid peroxidation inhibition,underscoring its role in mitigating cardiovascular and ocular diseases.Similarly,quercetin,a ubiquitous flavonoid in onions and berries,exhibits remarkable ROS-scavenging capacity,with IC50 values of 0.55μg/mL,2,2-Diphenyl-1-picrylhydrazyl(DPPH)and 1.17μg/mL,2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS),supporting its use in reducing inflammation and neurodegeneration.The therapeutic promise of these compounds extends to disease-specific applications.Limonoids from citrus fruits,such as limonin(IC_(50)15-31μg/mL),enhance Phase II detoxification enzymes,offering protection against chemical carcinogens.Sulforaphane,a glucosinolate derived from cruciferous vegetables,shows potent anticancer activity with an IC50 of 85.66 mg in DPPH radical scavenging,whileβ-sitosterol(IC_(50)1.43-2.42 mM)inhibits tumor proliferation and cholesterol synthesis.Synergistic interactions further amplify their efficacy:phytoestrogens like genistein(IC_(50)13.00 ppm)and terpenoids such asα-pinene(IC_(50)12.57 mg/mL)collectively enhance antiinflammatory and antimicrobial responses,illustrating the multi-targeted nature of plant-based therapies.Beyond disease prevention,these compounds address age-related decline.Ascorbic acid(vitamin C),with an IC50 of 11.81μg/mL for antioxidant activity,mitigates skin aging and accelerates wound healing,while seleniumnanoparticles(IC_(50)0.437μg/mL)bolster immune function and reduce chemotherapy-induced toxicity.Dietary fibers,exemplified by sugar beet fibers(IC_(50)52.32μg/mL for DPPH scavenging),further contribute to cardiovascular health by lowering Low-Density Lipoprotein(LDL)cholesterol.This review not only catalogs the antioxidant prowess of phytochemicals but also highlights their translational potential.Advances in nanotechnology,such as nano-formulated curcumin,have overcome bioavailability challenges,enhancing clinical applicability.By integrating quantitative metrics(e.g.,IC50,radical scavenging rates)with mechanistic insights,this work bridges the gap between traditional knowledge and modern pharmacology.
基金supported in part by the National Natural Science Foundation of China(62273255,62350003,62088101)the Shanghai Science and Technology Cooperation Project(22510712000,21550760900)+1 种基金the Shanghai Municipal Science and Technology Major Project(2021SHZDZX0100)the Fundamental Research Funds for the Central Universities
文摘Dear Editor,This letter is concerned with the problem of time-varying formation tracking for heterogeneous multi-agent systems(MASs) under directed switching networks. For this purpose, our first step is to present some sufficient conditions for the exponential stability of a particular category of switched systems.
基金supported by the Ministry of Education and Science of the Republic of North Macedonia through the project“Utilizing AI and National Large Language Models to Advance Macedonian Language Capabilties”。
文摘Artificial intelligence(AI)is reshaping financial systems and services,as intelligent AI agents increasingly form the foundation of autonomous,goal-driven systems capable of reasoning,learning,and action.This review synthesizes recent research and developments in the application of AI agents across core financial domains.Specifically,it covers the deployment of agent-based AI in algorithmic trading,fraud detection,credit risk assessment,roboadvisory,and regulatory compliance(RegTech).The review focuses on advanced agent-based methodologies,including reinforcement learning,multi-agent systems,and autonomous decision-making frameworks,particularly those leveraging large language models(LLMs),contrasting these with traditional AI or purely statistical models.Our primary goals are to consolidate current knowledge,identify significant trends and architectural approaches,review the practical efficiency and impact of current applications,and delineate key challenges and promising future research directions.The increasing sophistication of AI agents offers unprecedented opportunities for innovation in finance,yet presents complex technical,ethical,and regulatory challenges that demand careful consideration and proactive strategies.This review aims to provide a comprehensive understanding of this rapidly evolving landscape,highlighting the role of agent-based AI in the ongoing transformation of the financial industry,and is intended to serve financial institutions,regulators,investors,analysts,researchers,and other key stakeholders in the financial ecosystem.
基金supported by the National Natural Science Foundation of China(62325304,U22B2046,62073079,62376029)the Jiangsu Provincial Scientific Research Center of Applied Mathematics(BK20233002)the China Postdoctoral Science Foundation(2023M730255,2024T171123)
文摘Dear Editor,This letter studies the bipartite consensus tracking problem for heterogeneous multi-agent systems with actuator faults and a leader's unknown time-varying control input. To handle such a problem, the continuous fault-tolerant control protocol via observer design is developed. In addition, it is strictly proved that the multi-agent system driven by the designed controllers can still achieve bipartite consensus tracking after faults occur.
基金supported by the National Natural Science Foundation of China Joint Fund for Enterprise Innovation and Development,Enrichment Mechanism and Stereoscopic Development of Shale Oil in Continental Rift Basins(No.U24B6002).
文摘Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,the migration behavior of temporary plugging agent(TPA),as a function of the concentration and particle size of TPA and cluster-perforation numbers,etc.,determining the effectiveness of this technique,remains unclear.Therefore,this study conducted innovatively a series of TPDF simulation experiments on transparent polymethyl methacrylate(PMMA)specimens(cubic block of 30 cm×30 cm×30 cm)to explore visually the migration behavior of TPA in multi-clustered HFs in a horizontal well.A laboratory hydraulic sandblasting perforation completion technique was implemented to simulate the multi-cluster perforations.All the distributions of wellbore,perforations,HFs,and TPA can be seen clearly inside the PMMA specimen post the experiment.The results show that there are four characteristic plugging positions for the TPA:mouth of HF,middle of HF,tip of HF,and the intersection of HFs.Small particle size TPA tends to migrate to the fracture tip for plugging,while large particle size TPA tends to plug at the fracture mouth.The migration of the TPA is influenced obviously by the morphology of the fracture wall.A smooth fracture wall is conducive to the migration of the TPA to the far end of HFs,but not conducive to generating the plugging zone and HF diversion.In contrast,a"leaf vein"fracture of rough wall is conducive to generating the plugging layer and the diversion of HFs,but not conducive to the migration of the TPA to the far end of HFs.The migration ability of TPA in a"shell"pattern is intermediate between the two above cases.Increasing TPA concentration can encourage TPA to migrate more quickly to the characteristic plugging position,and thereby to promote the creation of effective plugging and subsequently the multi-stage diversion of the HFs.Nevertheless,excessive concentration may cause the TPA to settle prematurely,affecting the propagation of the HFs to the far end.Increasing the number of clusters to a certain extent can encourage TPA to migrate into the HFs and form plugging,and promote the diversion.An evaluation system for the migration ability of granular TPA has been established,and it was calculated that when there is no plugging expectation target,the comprehensive migration ability of small particle size TPA is stronger than that of large particle size TPA.This research provides theoretical foundation for the optimization of temporary plugging parameters.
文摘The chemical structure of polyamide 6(PA6)dictates that only 50%of hydrogen bonds participate in crystallization during the crystallization process,resulting in the properties of its products being significantly dependent on the molding process.Therefore,the design and development of nucleating agents suitable for PA6 holds great practical significance for high-performance PA6 materials.Amide-based nucleating agents can effectively improve the crystallization rate by increasing intermolecular hydrogen bond density.Further introduction of hydroxyl groups can enhance the hydrogen bonding interactions between the nucleating agent and PA6.In this study,a hydroxyl-containing amidebased nucleating agent,BHT,was designed and synthesized using a tyramine-based biomass as the raw material.These results demonstrated that BHT exhibited good structural compatibility with PA6.After adding 1 wt%BHT,the crystallization temperature of PA6 increased from 170.9℃to 193.3℃,the crystallinity increased 16.6%,the heat distortion temperature and Vicat softening temperature rose to 89.5 and 187.8℃,respectively,the haze decreased to 46%,achieving the synergistic optimization of mechanical,thermal,and optical properties.The in situ time-resolved FTIR results indicated that the addition of BHT increased the enthalpy of hydrogen bond formation during the nucleation stage,facilitated the segmental conformation adjustment of PA6,and enhanced the molar concentration of trans-conformations,ultimately leading to an improvement in the crystallization rate.
基金supported by the National Natural Science Foundation of China (NSFC grant no. 62474028, 52130304, and62222503)the Natural Science Foundation of Sichuan Province(2025ZNSFSC0037, 2025ZNSFSC1460, and 2024NSFSC1447)+1 种基金the National Key R and D Program of China (2023YFB2604101)sponsored by the Sichuan Province Key Laboratory of Display Science and Technology
文摘The crystallization and aggregation characteristics of the active layer components in organic solar cells(OSCs)are one of the core factors determining photovoltaic performance,influencing the entire process from light absorption to charge separation,transport,and ultimately charge collection.Dynamic changes in crystallization and aggregation states can also disrupt the microstructure of the active layer,thus shortening the lifetime of the cell.In this study,a morphology modulation strategy is proposed to regulate the crystallization kinetics of non-fullerene acceptors by employing the polymer molecule PYIT as a nucleating agent.An appropriate amount of PYIT was first completely dissolved with the non-fullerene acceptor Y6 and left to stand for 24 h,followed by the fabrication of layer-by-layer processed OSCs.Experiments demonstrated that high crystallinity of PYIT allows it to act as a crystallization nucleus,promoting the crystallization,orientation consistency,and ordered stacking of the acceptor.These nanoscale structural optimizations facilitate efficient charge transport,enhance exciton dissociation efficiency,and suppress unfavorable energetic disorder.Consequently,not only was the power conversion efficiency(PCE)of D18-Cl/Y6-based layer-by-layer processed OSC increased from 18.08%to 19.13%,but the atmospheric stability and long-term lifetime of the OSCs were also significantly improved.Notably,this strategy is also applicable to indoor OSCs,and the PYIT-optimized device can achieve a PCE of 27.0%under 1000 lux light-emitting diode(LED,3200K)irradiation,which is superior to that of the control device(24.2%).This work develops a crystal engineering strategy that is able to simultaneously optimize the microscopic morphology and charge dynamics properties in OSCs,thereby achieving simultaneous improvement in efficiency and stability.
