To clarify the densification behavior,deformation response and strengthening mechanisms of selective laser melted(SLM)Mg-RE alloys,this study systematically investigates a representative WE43 alloy via advanced materi...To clarify the densification behavior,deformation response and strengthening mechanisms of selective laser melted(SLM)Mg-RE alloys,this study systematically investigates a representative WE43 alloy via advanced material characterization techniques.A suitable laser output mode fell into the transition mode,allowing for the fabrication of nearly full-density samples(porosity=0.85±0.021%)with favorable mechanical properties(yield strength=351 MPa,ultimate tensile strength=417 MPa,the elongation at break=6.5%and microhardness=137.9±6.15 HV_(0.1))using optimal processing parameters(P=80 W,v=250 mm/s and d=50μm).Viscoplastic self-consistent analysis and transmission electron microscopy observations reveal that the plastic deformation response of the SLM Mg-RE alloys is primarily driven by basal and prismatic slips.Starting from a random texture before deformation(maximum multiple of ultimate density,Max.MUD=3.95),plastic stretching led the grains to align with the Z-axis,finally resulting in a{0001}<1010>texture orientation after fracture(Max.MUD=8.755).Main phases of the SLM state are mainly composed ofα-Mg,Mg_(24)Y_(5) andβ'-Mg_(41)Nd_(5),with an average grain size of only 4.27μm(about a quarter of that in the extruded state),resulting in a favorable strength-toughness ratio.Except for the nano-β'phase and semi-coherent Mg_(24)Y_(5) phase(mismatch=16.12%)around the grain boundaries,a small amount of nano-ZrO_(2) and Y_(2)O_(3) particles also play a role in dispersion strengthening.The high mechanical properties of the SLM state are chiefly attributed to precipitation hardening(44.41%),solid solution strengthening(34.06%)and grain boundary strengthening(21.53%),with precipitation hardening being predominantly driven by dislocation strengthening(67.77%).High-performance SLM Mg-RE alloy components were manufactured and showcased at TCT Asia 2024,receiving favorable attention.This work underscores the significant application potential of SLM Mg-RE alloys and establishes a strong foundation for advancing their use in the biomedical fields.展开更多
The pressure comfort of passengers and crew in high-speed trains faces significant challenges under alternating open-tunnel conditions.To better understand the mechanism of pressure transmission and control interior p...The pressure comfort of passengers and crew in high-speed trains faces significant challenges under alternating open-tunnel conditions.To better understand the mechanism of pressure transmission and control interior pressure fluctuations in high-altitude regions,this study develops an interior pressure fluctuation model.By establishing the frameworks of the non-ideal gas state equation and the polytropic process equation,gas heat transfer and mass transfer were expressed through the first law of thermodynamics and the continuity equation.Simulation results,evaluated by root mean square error,coefficient of determination,peak-to-peak error,and pressure change rate,show that the proposed model closely aligns with measured signals in both overall trends and local details.Data from various train types and tunnel scenarios further demonstrate the model's accuracy and practical applicability.This study provides a critical foundation for evaluating interior pressure comfort for high-speed trains in high-altitude regions.展开更多
This study aimed to compare the eff ectiveness and safety of diff erent tidal volumes combined with breath-holding during inhalation for clearing airway retention,and to explore optimized strategies for preventing ven...This study aimed to compare the eff ectiveness and safety of diff erent tidal volumes combined with breath-holding during inhalation for clearing airway retention,and to explore optimized strategies for preventing ventilator-associated pneumonia(VAP).The study enrolled 105 adult patients receiving mechanical ventilation at the Emergency ICU of Dalian University of Technology Affiliated Central Hospital from April 2023 to June 2024.Using a randomized digital table method,patients were divided into three groups(A,B,C)with tidal volumes of 8ml/kg,10ml/kg,and 12ml/kg respectively.Standardized VAP prevention measures were implemented alongside daily four-time-point airway clearance through ventilator-assisted breath-holding.Results showed that Group C demonstrated significantly higher post-operation airway clearance(p<0.001)and more frequent coughing(median 3 vs.2 times)compared to Groups A and B,indicating that higher tidal volumes enhance secretions expulsion.No signifi cant diff erences were observed in airway retention characteristics(color,viscosity)among groups(p>0.05).Regarding safety,all groups maintained normal heart rate and blood pressure fl uctuations before and after procedures,with oxygenation index briefly declining but rapidly recovering without severe hypoxemia.However,Group C exhibited a higher proportion of peak airway pressure>35 cmH₂O(8.6%)compared to Groups A and B(2.9%).Clinically,Group C had a lower VAP incidence(14.2%)than Group A(22.9%)but higher than Group B(11.4%),though statistically insignifi cant(p=0.32).ICU length of stay was shorter in Group C,but this diff erence was not statistically signifi cant(p=0.15).No aspiration or suff ocation occurred across all groups.This study demonstrates that the combination of 12ml/kg tidal volume and breath-holding during inhalation can more eff ectively clear airway retention without signifi cantly increasing safety risks.We recommend prioritizing this approach for mechanically ventilated patients with adequate lung function,while adjusting tidal volume through individualized assessment.Future research should further validate long-term outcomes and evaluate its effi cacy across multiple centers.展开更多
目的分析一体式蜗内耳蜗电图在人工耳蜗植入(CI)术中的应用情况,讨论其优势及局限,总结该技术的标准化流程。方法收集2023年3月~2025年8月于本团队实施人工耳蜗术中一体式蜗内耳蜗电图的全部临床资料及术中监测数据,对监测成功率、监测...目的分析一体式蜗内耳蜗电图在人工耳蜗植入(CI)术中的应用情况,讨论其优势及局限,总结该技术的标准化流程。方法收集2023年3月~2025年8月于本团队实施人工耳蜗术中一体式蜗内耳蜗电图的全部临床资料及术中监测数据,对监测成功率、监测指标变化规律等进行分析,建立术中监测三阶段分型(植入早期、中期和晚期;上升型、下降型、稳定型、波动型)。结果共有44例(45耳)患者应用该技术(男24,女20),平均年龄27.3±19.2岁,术前低频平均听力为86.6±21.1 dB HL,无明显的耳蜗畸形,均完成全部电极植入。15耳成功在术中引出CM波形,9耳于术毕或术后第2天引出波形,21耳未引出波形(其中9耳术中干扰严重,2耳术中耳机脱落)。在去除术中干扰严重的9耳和术中耳机脱落的2耳后,34耳的术中CM波形引出率与术前低频平均听力之间无统计学意义(n=34,χ^(2)=1.145,P=0.451),且该34耳以及术中成功引出15耳耳蜗微音电位(cochlear microphonics,CM)波形最大幅值与术前低频平均听力无明显相关(n=34,r=-0.015,P=0.931;n=15,r=0.237,P=0.395)。15耳中,植入早期最常见为波动型[7耳(46.7%)],其中4耳依据波形变化采用优化植入干预方案;在中期为稳定型和波动型居多[均为5耳(33.3%)];在晚期,各类型比例相近,且波形下降趋势难以通过干预方案得到恢复。在本院完成术后开机随访且具有术前可测听力的12例(12耳)患者,术后低频听力完全保留率为75%,部分保留率为25%。术毕/术中最高幅值比与术后低频听力阈移呈显著负相关(r=-0.707,P=0.01)。结论术中应用ECochG技术可实时反馈电极植入对内耳的创伤,及时在损伤可逆期内进行微创化调整,有助于术后残余听力的保留。术中标准化流程的建立有助于提升该技术的术中引出率。术中监测三阶段分型的建立有助于电极植入对内耳创伤的机制分析。术中CM波形引出率、引出幅值与术前低频平均听力的关系仍待进一步探讨分析。展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFC2406000)the Guangdong Basic and Applied Basic Research Foundation(2024A1515011024)+5 种基金the Guangzhou Science and Technology Project(2024A04J4943)the Guangdong Academy of Sciences Development Special Fund Project(2022GDASZH-2022010107)the Guangdong province Science and Technology Plan Projects(2023B1212120008,2023B1212060045)the GDAS Projects of International cooperation platform of Science and Technology(2022GDASZH-2022010203-003)Special Support Foundation of Guangdong Province(2023TQ07Z559)Shenzhen Basic Research Project(JCYJ20210324120001003 and JCYJ20220531091802006)。
文摘To clarify the densification behavior,deformation response and strengthening mechanisms of selective laser melted(SLM)Mg-RE alloys,this study systematically investigates a representative WE43 alloy via advanced material characterization techniques.A suitable laser output mode fell into the transition mode,allowing for the fabrication of nearly full-density samples(porosity=0.85±0.021%)with favorable mechanical properties(yield strength=351 MPa,ultimate tensile strength=417 MPa,the elongation at break=6.5%and microhardness=137.9±6.15 HV_(0.1))using optimal processing parameters(P=80 W,v=250 mm/s and d=50μm).Viscoplastic self-consistent analysis and transmission electron microscopy observations reveal that the plastic deformation response of the SLM Mg-RE alloys is primarily driven by basal and prismatic slips.Starting from a random texture before deformation(maximum multiple of ultimate density,Max.MUD=3.95),plastic stretching led the grains to align with the Z-axis,finally resulting in a{0001}<1010>texture orientation after fracture(Max.MUD=8.755).Main phases of the SLM state are mainly composed ofα-Mg,Mg_(24)Y_(5) andβ'-Mg_(41)Nd_(5),with an average grain size of only 4.27μm(about a quarter of that in the extruded state),resulting in a favorable strength-toughness ratio.Except for the nano-β'phase and semi-coherent Mg_(24)Y_(5) phase(mismatch=16.12%)around the grain boundaries,a small amount of nano-ZrO_(2) and Y_(2)O_(3) particles also play a role in dispersion strengthening.The high mechanical properties of the SLM state are chiefly attributed to precipitation hardening(44.41%),solid solution strengthening(34.06%)and grain boundary strengthening(21.53%),with precipitation hardening being predominantly driven by dislocation strengthening(67.77%).High-performance SLM Mg-RE alloy components were manufactured and showcased at TCT Asia 2024,receiving favorable attention.This work underscores the significant application potential of SLM Mg-RE alloys and establishes a strong foundation for advancing their use in the biomedical fields.
基金Project(52372402)supported by the National Natural Science Foundation of China。
文摘The pressure comfort of passengers and crew in high-speed trains faces significant challenges under alternating open-tunnel conditions.To better understand the mechanism of pressure transmission and control interior pressure fluctuations in high-altitude regions,this study develops an interior pressure fluctuation model.By establishing the frameworks of the non-ideal gas state equation and the polytropic process equation,gas heat transfer and mass transfer were expressed through the first law of thermodynamics and the continuity equation.Simulation results,evaluated by root mean square error,coefficient of determination,peak-to-peak error,and pressure change rate,show that the proposed model closely aligns with measured signals in both overall trends and local details.Data from various train types and tunnel scenarios further demonstrate the model's accuracy and practical applicability.This study provides a critical foundation for evaluating interior pressure comfort for high-speed trains in high-altitude regions.
文摘This study aimed to compare the eff ectiveness and safety of diff erent tidal volumes combined with breath-holding during inhalation for clearing airway retention,and to explore optimized strategies for preventing ventilator-associated pneumonia(VAP).The study enrolled 105 adult patients receiving mechanical ventilation at the Emergency ICU of Dalian University of Technology Affiliated Central Hospital from April 2023 to June 2024.Using a randomized digital table method,patients were divided into three groups(A,B,C)with tidal volumes of 8ml/kg,10ml/kg,and 12ml/kg respectively.Standardized VAP prevention measures were implemented alongside daily four-time-point airway clearance through ventilator-assisted breath-holding.Results showed that Group C demonstrated significantly higher post-operation airway clearance(p<0.001)and more frequent coughing(median 3 vs.2 times)compared to Groups A and B,indicating that higher tidal volumes enhance secretions expulsion.No signifi cant diff erences were observed in airway retention characteristics(color,viscosity)among groups(p>0.05).Regarding safety,all groups maintained normal heart rate and blood pressure fl uctuations before and after procedures,with oxygenation index briefly declining but rapidly recovering without severe hypoxemia.However,Group C exhibited a higher proportion of peak airway pressure>35 cmH₂O(8.6%)compared to Groups A and B(2.9%).Clinically,Group C had a lower VAP incidence(14.2%)than Group A(22.9%)but higher than Group B(11.4%),though statistically insignifi cant(p=0.32).ICU length of stay was shorter in Group C,but this diff erence was not statistically signifi cant(p=0.15).No aspiration or suff ocation occurred across all groups.This study demonstrates that the combination of 12ml/kg tidal volume and breath-holding during inhalation can more eff ectively clear airway retention without signifi cantly increasing safety risks.We recommend prioritizing this approach for mechanically ventilated patients with adequate lung function,while adjusting tidal volume through individualized assessment.Future research should further validate long-term outcomes and evaluate its effi cacy across multiple centers.
文摘目的分析一体式蜗内耳蜗电图在人工耳蜗植入(CI)术中的应用情况,讨论其优势及局限,总结该技术的标准化流程。方法收集2023年3月~2025年8月于本团队实施人工耳蜗术中一体式蜗内耳蜗电图的全部临床资料及术中监测数据,对监测成功率、监测指标变化规律等进行分析,建立术中监测三阶段分型(植入早期、中期和晚期;上升型、下降型、稳定型、波动型)。结果共有44例(45耳)患者应用该技术(男24,女20),平均年龄27.3±19.2岁,术前低频平均听力为86.6±21.1 dB HL,无明显的耳蜗畸形,均完成全部电极植入。15耳成功在术中引出CM波形,9耳于术毕或术后第2天引出波形,21耳未引出波形(其中9耳术中干扰严重,2耳术中耳机脱落)。在去除术中干扰严重的9耳和术中耳机脱落的2耳后,34耳的术中CM波形引出率与术前低频平均听力之间无统计学意义(n=34,χ^(2)=1.145,P=0.451),且该34耳以及术中成功引出15耳耳蜗微音电位(cochlear microphonics,CM)波形最大幅值与术前低频平均听力无明显相关(n=34,r=-0.015,P=0.931;n=15,r=0.237,P=0.395)。15耳中,植入早期最常见为波动型[7耳(46.7%)],其中4耳依据波形变化采用优化植入干预方案;在中期为稳定型和波动型居多[均为5耳(33.3%)];在晚期,各类型比例相近,且波形下降趋势难以通过干预方案得到恢复。在本院完成术后开机随访且具有术前可测听力的12例(12耳)患者,术后低频听力完全保留率为75%,部分保留率为25%。术毕/术中最高幅值比与术后低频听力阈移呈显著负相关(r=-0.707,P=0.01)。结论术中应用ECochG技术可实时反馈电极植入对内耳的创伤,及时在损伤可逆期内进行微创化调整,有助于术后残余听力的保留。术中标准化流程的建立有助于提升该技术的术中引出率。术中监测三阶段分型的建立有助于电极植入对内耳创伤的机制分析。术中CM波形引出率、引出幅值与术前低频平均听力的关系仍待进一步探讨分析。
