A comprehensive three-dimensional transient computational fluid dynamics(CFD)model was developed to ana-lyze the thermophysical phenomena in the arc wire additive manufacturing(WAAM)process.The model includes droplet ...A comprehensive three-dimensional transient computational fluid dynamics(CFD)model was developed to ana-lyze the thermophysical phenomena in the arc wire additive manufacturing(WAAM)process.The model includes droplet impact,gravity,heat and mass transfer,molten metal flow,and solid-liquid phase changes.By integrating the mass,energy,momentum,and volume of fluid(VOF)equations,a layer-by-layer additive process was suc-cessfully simulated.The accuracy of the model was validated by comparing the simulation results of single-pass single-layer weld beads at three welding positions with experimental data.The established model was utilized to quantitatively investigate the effects of three crucial welding process parameters-welding direction,droplet transfer frequency,and initial temperature-on the multi-layer cladding process.These findings suggest that the use of opposite welding directions in two adjacent layers can result in a well-distributed overall morphology of the weld bead.Moreover,the high initial droplet temperature enhanced the inclination of the weld bead mor-phology while decreasing the height of each layer.However,the high droplet transfer frequency caused both the height and width of the weld to increase.This research contributes to explaining the formation mechanism of the multi-layer cladding process and offers insights for improving weld bead morphology.This provides valuable theoretical guidance for the process optimization and control of arc additive manufacturing technology.展开更多
Banana is sensitive to cold stress and often suffers from chilling injury with browning peel and failure to normal ripening.We have previously reported that banana chilling injury is accompanied by a reduction of miR5...Banana is sensitive to cold stress and often suffers from chilling injury with browning peel and failure to normal ripening.We have previously reported that banana chilling injury is accompanied by a reduction of miR528 accumulation,alleviating the degradation of its target gene MaPPO and raising ROS levels that cause peel browning.Here,we further revealed that the miR528-MaPPO cold-responsive module was regulated by miR156-targeted SPL transcription factors,and the miR156c-MaSPL4 module was also responsive to cold stress in banana.Transient overexpression of miR156c resulted in a more severe chilling phenotype by decreasing the expression of MaSPL4 and miR528.Conversely,the browning was alleviated in STTM-miR156c silencing and OE-MaSPL4 samples.Furthermore,DNA affinity purification sequencing and MaSPL4-overexpressing transcriptome jointly revealed that MaSPL4 may mediate the transcription of genes related to lipid metabolism and antioxidation,in addition to the miR528-MaPPO module,demonstrating MaSPL4 as a master regulator in the fruit cold response network.In summary,our results suggest that the miR156c-MaSPL4 module can mediate the chilling response in banana by regulating the miR528-MaPPO module and multiple other pathways,which provides evidence for the crosstalk between TFs and miRNAs that can be used for the molecular breeding of fruit cold tolerance.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.52076216,51706246).
文摘A comprehensive three-dimensional transient computational fluid dynamics(CFD)model was developed to ana-lyze the thermophysical phenomena in the arc wire additive manufacturing(WAAM)process.The model includes droplet impact,gravity,heat and mass transfer,molten metal flow,and solid-liquid phase changes.By integrating the mass,energy,momentum,and volume of fluid(VOF)equations,a layer-by-layer additive process was suc-cessfully simulated.The accuracy of the model was validated by comparing the simulation results of single-pass single-layer weld beads at three welding positions with experimental data.The established model was utilized to quantitatively investigate the effects of three crucial welding process parameters-welding direction,droplet transfer frequency,and initial temperature-on the multi-layer cladding process.These findings suggest that the use of opposite welding directions in two adjacent layers can result in a well-distributed overall morphology of the weld bead.Moreover,the high initial droplet temperature enhanced the inclination of the weld bead mor-phology while decreasing the height of each layer.However,the high droplet transfer frequency caused both the height and width of the weld to increase.This research contributes to explaining the formation mechanism of the multi-layer cladding process and offers insights for improving weld bead morphology.This provides valuable theoretical guidance for the process optimization and control of arc additive manufacturing technology.
基金funded by National Natural Science Foundation of China(#32372781,#32371926)Basic and Applied Basic Research Foundation of Guangdong Province(Grant No.2024A1515012759)+1 种基金Guangdong Science and Technology Plan Project(Grant No.2023B1212060046)the CAS President’s International Fellowship Initiative(2024VBA0005).
文摘Banana is sensitive to cold stress and often suffers from chilling injury with browning peel and failure to normal ripening.We have previously reported that banana chilling injury is accompanied by a reduction of miR528 accumulation,alleviating the degradation of its target gene MaPPO and raising ROS levels that cause peel browning.Here,we further revealed that the miR528-MaPPO cold-responsive module was regulated by miR156-targeted SPL transcription factors,and the miR156c-MaSPL4 module was also responsive to cold stress in banana.Transient overexpression of miR156c resulted in a more severe chilling phenotype by decreasing the expression of MaSPL4 and miR528.Conversely,the browning was alleviated in STTM-miR156c silencing and OE-MaSPL4 samples.Furthermore,DNA affinity purification sequencing and MaSPL4-overexpressing transcriptome jointly revealed that MaSPL4 may mediate the transcription of genes related to lipid metabolism and antioxidation,in addition to the miR528-MaPPO module,demonstrating MaSPL4 as a master regulator in the fruit cold response network.In summary,our results suggest that the miR156c-MaSPL4 module can mediate the chilling response in banana by regulating the miR528-MaPPO module and multiple other pathways,which provides evidence for the crosstalk between TFs and miRNAs that can be used for the molecular breeding of fruit cold tolerance.
