Influence of Tempering Temperature and Time on Microstructure and Mechanical Properties of Additively Manufactured H13 Tool Steel

Among various processes for manufacturing complex-shaped metal parts, additive manufacturing is highlighted as a process capable of reducing the wastage of materials without requiring a post-process, such as machining and finishing. In particular, it is a suitable new manufacturing technology for producing AISI H13 tool steel for hot-worked molds with complex cooling channels. In this study, we manufactured AISI H13 tool steel using the laser power bed fusion (LPBF) process and investigated the effects of tempering temperature and holding time on its microstructure and mechanical properties. The mechanical properties of the sub-grain cell microstructure of the AISI H13 tool steel manufactured using the LPBF process were superior to that of the H13 tool steel manufactured using the conventional method. These sub-grain cells decomposed and disappeared during the austenitizing process; however, the mechanical properties could be restored at a tempering temperature of 500 °C or higher owing to the secondary hardening and distribution of carbides. Furthermore, the mechanical properties deteriorated because of the decomposition of the martensite phase and the accumulation and coarsening of carbides when over-tempering occurred at 500 °C for 5 h and 550 °C for 3 h.     

Use of Fluidized Bed Combustion Fly Ash as a Partial Substitute for Cement in Underwater Concrete Mixes

Despite limitations to coal combustion energy production, many countries face the still-unresolved problem of utilising the wastes from fluidised bed coal combustion. One direction of rational utilisation can be using these wastes in the building materials industry. The study aimed to analyse the possibility of using fluidised bed combustion fly ashes as a partial substitute for cement in the underwater concrete (UWC). Two groups of concrete mixes were tested, containing 20 to 50% of fluidised bed combustion fly ashes. Investigations of the rheological properties of the concrete mixes and the mechanical performance of the hardened concrete confirmed the possibility of replacing cement in UWC with fluidised bed combustion fly ash up to 30% of the cement mass. The higher content of the fly ashes significantly worsens the UWC strength as well as the consistency and wash-out loss of the concrete mixes, excluding its use in underwater concreting.     

苯甲酸钠喷雾沸腾造粒

本文介绍一种用流态化技术与喷雾干燥相结合的方法将苯甲酸钠溶液在流化床内完成蒸发、干燥与造粒。     

清火片生产工艺优选

目的摸索清火片的制备工艺,提高清火片的质量。方法以一步制粒法制备颗粒,并将薄荷脑用β-环糊精包合,制成包合物后加入压片。结果以该法制备的清火片,外观、成品颗粒、片剂崩解时限及包衣片的外观质量均优于传统制法。结论清火片工艺合理可行。     

在线近红外光谱监测桂枝茯苓胶囊流化床干燥过程水分的方法研究

目的采用在线近红外光谱(NIRS)技术,建立桂枝茯苓胶囊流化床干燥过程水分实时监测模型。方法通过NIRS漫反射探头采集16个生产批次共176个样本进行建模,优选移动窗口平滑法进行光谱预处理,采用间隔偏最小二乘法(si PLS)结合移动窗口偏最小二乘法(mw PLS)筛选特征变量为4 759.45～5 338.00 cm-1、5 503.84～6 101.67 cm-1、8 512.25～8 809.24cm-1,采用偏最小二乘(PLS)法建立水分含量多变量校正模型。结果水分预测的交叉验证均方根误差(RMSECV)为0.243%,性能偏差比(RPD)值为13.384,预测相对偏差(RSEP)为0.270%。以8个生产批次对在线监控方法的可靠性进行持续验证,结果 40个样本的相对预测误差均小于4.7%。干燥过程水分实时监测趋势图显示可准确判断干燥终点,终点样本水分含量位于控制限内。结论在线NIRS结合PLS建立的定量模型,可应用于生产规模桂枝茯苓胶囊流化床干燥过程水分含量在线监控且预测性能稳健、准确。     

食管癌术后纵隔各分区的淋巴结转移概率研究

目的：分析各段食管癌术后局部复发模式,探讨食管癌术后辅助性调强放疗的靶区勾画技巧,缩小照射野,降低放疗毒副作用.方法：收集589例接受根治性切除的食管癌患者临床资料.其中术后复发157例,淋巴结复发83.4％（131例）,瘤床复发9.6％（15例,包括合并淋巴结复发6例）,吻合口复发5.7％（9例,包括合并淋巴结复发4例,合并残胃复发1例）,残胃复发1.3％（2例）.结果：各段食管癌术后的复发模式以区域淋巴结转移为主,食管癌淋巴结复发仍以纵隔淋巴结转移为主,纵隔1R区淋巴结复发明显高于其他分区,并且没有纵隔5区淋巴结复发.贲门癌以腹腔淋巴结复发为主;T4、T3、T2期患者手术后瘤床复发的风险分别为19.1％、1.4％、1.5％,瘤床复发主要为T4期患者.结论：临床上做食管癌术后辅助性调强放疗时,CTV可以根据不同部位食管癌的复发模式及淋巴结转移规律进一步缩小照射野.食管癌根治术后放疗靶区应设计为：上段食管癌应包括双锁骨上,纵隔1、2、4、7、3P区,瘤床,吻合口;中、下段食管癌术后放疗靶区包括双锁骨上,纵隔1、2、4、7、3P区,吻合口.T4期患者包括瘤床即可,瘤床下界置于原发灶下界即可.T3以上患者由于瘤床复发几率很低,可甩掉瘤床的照射.对于术后清扫贲门或胃左淋巴结阳性的患者可照射腹腔淋巴结引流区,包括腹腔3、7、8、9、16a组淋巴引流区;贲门癌包括瘤床,腹腔33、8、9、10、11、16a组淋巴引流区.     

5-0铬制肠线用于急诊修复甲床裂伤

目的探讨5-0铬制肠线用于急诊修复甲床裂伤的效果。方法选择43例甲床裂伤患者,使用5-0铬制肠线急诊修复甲床并甲板原位缝合,随访3-6个月,观察临床治疗效果。结果术后随访3-6个月,以最后一次评定结果为疗效。43例45指疗效评定,优39指,良4指,可2指,总优良率95.6%。结论应用5-0铬制肠线用于急诊修复甲床裂伤手术简单有效,适用于急诊科急诊治疗甲床裂伤。     

耳穴压豆治疗骨科卧床患者便秘的疗效研究

目的探讨耳穴压豆疗法治疗骨科卧床患者便秘的临床疗效。方法将80例骨科卧床便秘患者按照入院日期单双数分为耳穴压豆组和对照组各40例,主要从首次排便时间和排便间隔时间方面进行对比观察。治疗组耳穴压豆主穴取大肠、小肠、交感、直肠下段,两耳交替,3天更换穴贴1次,连续治疗10d。对照组口服酚酞,2片/次,3次/d,连续治疗10d。结果 （1）两组患者首次排便时间比较差异有统计学意义（P〈0.05）,说明耳穴压豆组在首次排便时间方面疗效优于对照组。（2）两组患者排便间隔时间比较差异具有统计学意义（P〈0.05）,说明耳穴压豆组在排便间隔时间方面优于对照组。结论中医技术耳穴压豆法对治疗骨科卧床患者便秘疗效显著,由于方法简便易行,病人依从性高,值得临床推广。     

子痫前期患者可溶性血管内皮生长因子及其受体与子宫胎盘床螺旋动脉变化及意义

目的研究可溶性血管内皮生长因子受体1(sFlt-1)和血管内皮生长因子(VEGF)在子痫前期患者血清中的浓度变化,以及子宫胎盘床螺旋动脉的相应变化,探讨sFlt-1和VEGF在子痫前期中的作用。方法采用酶联免疫吸附试验(ELISA)分别测定轻度子痫前期、重度子痫前期患者及正常妊娠妇女外周血清中sFlt-1和VEGF的浓度。同时按照Robertson方法,获取胎盘床活检标本,在光学显微镜下观察子痫前期组与对照组胎盘床螺旋动脉的生理性变化。结果(1)子痫前期组各组外周血清中sFlt-1水平明显高于对照组(P<0.01),子痫前期重度组高于子痫前期轻度组(P<0.05);(2)子痫前期组各组外周血血清中VEGF水平明显低于对照组(P<0.05),子痫前期重度组低于子痫前期轻度组(P<0.05)。正常妊娠组与子痫前期组胎盘床蜕膜螺旋动脉的生理性改变差异无统计学意义(P>0.05)。子痫前期组肌层螺旋动脉的生理性改变明显少于正常妊娠组,2组差别有统计学意义(P<0.05)。结论外周血中升高的sFlt-1和降低的VEGF以及相应的肌层螺旋动脉生理性改变可能与妊娠期高血压的发病有关,并参与了子痫前期病理生理过程。