Effect of long-term thermal exposure on microstructure of laser-welded UNS N10003 alloy

The evolution of the microstructure and tensile rupture mechanism of laser welds in UNS N10003 alloy exposed to 700℃are investigated.Fine M_(6)C carbides precipitate around the primary eutectic M_(6)C-carbides in the fusion zone after 100 h of exposure.During long-term thermal exposure,the size of the fine M_(6)C carbides increased.The eutectic M_(6)C-carbides in the as-welded fusion zone transformed into spherical M_(6)C carbides as the exposure time extends to 10000 h.Additionally,the spherical M_(6)C particles exhibit size coarsening with increasing exposure time.The tensile properties of the welded joints are not adversely affected by the evolution of eutectic M_(6)C-carbides and the coarsening of M_(6)C carbides.

超声引导下腰方肌阻滞联合应用纳布啡对剖宫产术后镇痛的效果

目的探讨超声引导下腰方肌阻滞联用纳布啡在剖宫产术后镇痛中的效果。方法选取2021年4月至2022年4月在深圳市宝安区妇幼保健院产科接受剖宫产术的初产妇为研究对象,基于随机数字表法分成研究组与对照组。对照组术后行纳布啡静脉自控镇痛(patient-controlled intravenous analgesia,PCIA),研究组行超声引导下腰方肌阻滞联用纳布啡。观察两组术前及术后4 h、8 h、12 h、24 h的血压、心率,并应用视觉模拟评分(visual analogue scale,VAS)评估术后4 h、8 h、12 h、24 h切口疼痛度,应用Ramsay镇静评分评估术后镇静状态,了解镇痛泵应用情况。结果共纳入110例产妇,研究组和对照组各55例。与对照组相比,研究组术后4 h、8 h、12 h、24 h的心率、平均动脉压、VAS评分均显著降低(P<0.05),术后1 h、6 h Ramsay镇静评分升高(P<0.05)。研究组首次按压镇痛泵时间大于对照组,术后24 h内镇痛泵有效按压次数小于对照组(P<0.05)。结论在剖宫产术后镇痛中采取超声引导下腰方肌阻滞联用纳布啡,可有效减轻术后疼痛,且术后镇静效果良好。