Ultra-high-strength aluminumalloy profile is an ideal choice for aerospace structuralmaterials due to its excellent specific strength and corrosion resistance.However,issues such as uneven metal flow,stress concentrat...Ultra-high-strength aluminumalloy profile is an ideal choice for aerospace structuralmaterials due to its excellent specific strength and corrosion resistance.However,issues such as uneven metal flow,stress concentration,and forming defects are prone to occur during their extrusion.This study focuses on an Al-Zn-Mg-Cu ultra-high-strength aluminum alloy profile with a double-U,multi-cavity thin-walled structure.Firstly,hot compression experiments were conducted at temperatures of 350○C,400○C,and 450○C,with strain rates of 0.01 and 1.0 s^(−1),to investigate the plastic deformation behavior of the material.Subsequently,a 3D coupled thermo-mechanical extrusion simulation model was established using Deform-3D to systematically analyze the influence of die structure and process parameters on metal flow velocity,effective stress/strain,and temperature distribution.The simulation revealed significant velocity differences,stress concentration,and uneven temperature distribution.Key parameters,including mesh density,extrusion ratio,die fillet,and bearing length,were optimized through full-factorial experiments.This optimization,combined with a stepped flow-guiding die design,effectively improved the metal flow pattern during extrusion.Trial production based on both the initial and optimized parameters were carried out.A comparative analysis demonstrates that the optimized scheme results in a final profile whose cross-section matches the target design closely,with complete filling of complex features and no obvious forming defects.This research provides a valuable reference for the extrusion process optimization and die design of complex-section profiles made from ultra-high-strength aluminum alloys.展开更多
The global environmental issue of soil contamination with antibiotic-resistance genes has garnered increased attention in recent years due to its impact on ecosystems and human health.Despite this recognition,research...The global environmental issue of soil contamination with antibiotic-resistance genes has garnered increased attention in recent years due to its impact on ecosystems and human health.Despite this recognition,researchers face challenges in comprehensively understanding the mechanisms underlying the production and dissemination of soil resistance genes,particularly in relation to their implications for human health.This lack of understanding poses a barrier to the development of effective and precise control strategies.Biochar,a sustainable material,exhibits favorable adsorption properties characterized by its large pores and specific surface area.Therefore,we propose to explore the potential application of biochar addition in soil resistance gene management.In order to establish a solid research foundation in this area,in this paper we review the mechanisms underlying the generation and accumulation of soil resistance genes over the last decade,along with their transmission pathways and interfacial interactions.Biochar may help repair soil resistance genes by affecting factors like antibiotic levels,environmental conditions,enzymatic activity,and gene migration mechanisms,opening up new research possibilities.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2023YFB3710805).
文摘Ultra-high-strength aluminumalloy profile is an ideal choice for aerospace structuralmaterials due to its excellent specific strength and corrosion resistance.However,issues such as uneven metal flow,stress concentration,and forming defects are prone to occur during their extrusion.This study focuses on an Al-Zn-Mg-Cu ultra-high-strength aluminum alloy profile with a double-U,multi-cavity thin-walled structure.Firstly,hot compression experiments were conducted at temperatures of 350○C,400○C,and 450○C,with strain rates of 0.01 and 1.0 s^(−1),to investigate the plastic deformation behavior of the material.Subsequently,a 3D coupled thermo-mechanical extrusion simulation model was established using Deform-3D to systematically analyze the influence of die structure and process parameters on metal flow velocity,effective stress/strain,and temperature distribution.The simulation revealed significant velocity differences,stress concentration,and uneven temperature distribution.Key parameters,including mesh density,extrusion ratio,die fillet,and bearing length,were optimized through full-factorial experiments.This optimization,combined with a stepped flow-guiding die design,effectively improved the metal flow pattern during extrusion.Trial production based on both the initial and optimized parameters were carried out.A comparative analysis demonstrates that the optimized scheme results in a final profile whose cross-section matches the target design closely,with complete filling of complex features and no obvious forming defects.This research provides a valuable reference for the extrusion process optimization and die design of complex-section profiles made from ultra-high-strength aluminum alloys.
基金supported by the Key Technologies Research and Development Program[grant numbers 2019YFC1803804]Shenyang Science and Technology Program[grant numbers 22-322-3-01].
文摘The global environmental issue of soil contamination with antibiotic-resistance genes has garnered increased attention in recent years due to its impact on ecosystems and human health.Despite this recognition,researchers face challenges in comprehensively understanding the mechanisms underlying the production and dissemination of soil resistance genes,particularly in relation to their implications for human health.This lack of understanding poses a barrier to the development of effective and precise control strategies.Biochar,a sustainable material,exhibits favorable adsorption properties characterized by its large pores and specific surface area.Therefore,we propose to explore the potential application of biochar addition in soil resistance gene management.In order to establish a solid research foundation in this area,in this paper we review the mechanisms underlying the generation and accumulation of soil resistance genes over the last decade,along with their transmission pathways and interfacial interactions.Biochar may help repair soil resistance genes by affecting factors like antibiotic levels,environmental conditions,enzymatic activity,and gene migration mechanisms,opening up new research possibilities.
