Bending Fatigue Behaviour and Fatigue Endurance Limit Prediction of 20Cr2Ni4A Gear Steel after the Ultrasonic Surface Rolling Process

To study the effect of the surface properties on the bending fatigue performance of heavy-duty gear steel, the authors of this paper used the ultrasonic surface rolling process (USRP) to strengthen 20Cr2Ni4A carburized gear steel. USRP is a novel technique in which the ultrasonic technology is incorporated into the concept of conventional deep rolling. In this study, we illustrated how the surface properties and cross-section mechanical property influence the three-point bending fatigue life of the samples before and after USRP treatment. At the same time, the predicted failure probability-stress-number of cycles (P-S-N) curve was drawn, and the fatigue fracture was analysed. The results show that the fatigue limit increased from 651.36 MPa to 918.88 MPa after USRP treatment. The fatigue source is mainly from the sample interior or surface scratches, and the fatigue performance is positively correlated with the results of the material surface roughness, surface residual stress and surface hardness. At the same time, combined with the change in the phase structure, dislocation structure, residual stress and hardness of the cross section of the material, it is found that the USRP process turns the steel into a gradient material with five layers. Finally, the coupling mechanism between the ultrasonic surface strengthening deformation layer and the carburized layer of 20Cr2Ni4A carburized gear steel is presented, and the grain structure distribution diagram of the section of the 20Cr2Ni4A model after surface strengthening treatment was simulated. The mechanism that influenced the fatigue performance after USRP treatment is explained from the perspectives of the surface and cross section of the samples.     

四逆散加味治验3则

四逆散出自《伤寒论》,具有透解郁热、疏肝解郁理脾之效。近代伤寒宗师刘渡舟善用四逆散合方治疗肝郁之病,曰:"阳经之枢机,在于少阳;阴经之枢机,在于少阴。少阳者,用小柴胡汤加味以疏达之;少阴者,宜四逆散畅通少阴之枢以达其阳"。笔者受此启发,采用本方加味治疗因肝郁而致的顽固性失眠、冠心病、慢性胆囊炎等疾病,紧扣肝郁气滞之机,行疏肝理气,每获良效。     

THE ELIÁN GONZÁLEZ DISCURSIVE TEMPLATE

In this essay we return to the Elián González custody battle of 1999/2000 in order to investigate the lessons the case poses for understanding the conflicted mediation of childhood, and to ask why Elián's particular childhood continues to resonate widely years after his return to Cuba. Detailing how the Elián case ruptured the myth of Cuban exile exceptionalism, thereby ensuring that US Cubans became prey to the nativist discourses that historically targeted other US Latina/o groups, we also attend to the media, popular‐cultural, and international cooptions of the Elián story. Those cooptions indicate that the enduring and evolving Elián icon has come to provide an adaptable, differentially applied, and contradictory template by which numerous children have been pressed into symbolic service as “other Eliáns.” With this focus, we track the evolution of the Elián discursive template and its applications in cognate custody conflicts centred on the border‐crossing child as potential citizen.     

Rupture of the intra-articular portion of the long head of the biceps associated with a symptomatic os acromiale

We report the case of a 45-year-old male who presented with a 5-year history of shoulder pain following an injury. Clinical and radiological investigations revealed a ruptured long head of the biceps and a meso-os acromiale. We performed an arthroscopic resection of the intra-articular stump of the long head of the biceps, followed by internal fixation of the mobile os acromiale using a tension band technique. Rupture of the long head of the biceps associated with a symptomatic os acromiale has not been previously described. This case reinforces the importance of routine shoulder arthroscopy in the treatment of symptomatic os acromiale.     

The Location of Maxillary Sinus Ostium and Its Clinical Application

The endoscopic sinus surgeons must have a detailed knowledge of inconsistent location of maxillary sinus openings in any interventional maxillary sinus surgeries as it relates to the orbital floor, ethmoid infundibulum and the nasolacrimal duct. Forty cadaver head and neck specimens had been cut sagittally through the nose, such that the lateral nasal wall had been preserved. The findings were documented with an emphasis on location of the maxillary sinus openings. In the present study maxillary sinus ostium opened more commonly into posterior third of the hiatus semilunaris. Accessory maxillary ostium was another variation seen in nearly three-fourths of the cases which opened into membranous meatus inferior to the uncinate process.     

镁对镍、钴、锌、镉离子致蟾蜍胚胎毒性的影响

[目的 ]用FETAX设计 ,研究Mg2 对Ni2 、Co2 、Zn2 和Cd2 致Xenopus胚胎的胚胎毒性与致畸作用的影响。 [方法 ]在 7次检测中 ,分别于含Mg2 5个等级浓度 (0、6 2、62、62 0、62 0 0 μmol/L)的FETAX培养液中 ,设空白对照与加入NiCl2 (5 6μmol/L)、CoCl2 (180 0 μmol/L)、ZnCl2 (3 0 0 μmol/L)和CdCl2 (18μmol/L)的 2 5个组 ,每个组内的受精卵均经 5～10 1h孵育。在该检测中限定Mg2 (62 0 μmol/L)为标准浓度。在该浓度时Ni2 、Co2 、Zn2 和Cd2 组胚胎死亡率 <10 % ,畸形率 >95 %。 [结果 ]对照组于标准浓度时平均畸形率为 (5 4± 1 3 ) % ,低于该等级的 62 μmol/L为 (3 2± 7) % ,≤ 6 2μmol/L为 10 0 %。表明Mg2 不足与补加可极显著地增强与降低胚胎畸形率及其严重程度与胚胎毒性 (P <0 0 0 0 1,ANO VA分析 )。 [结论 ]对此 ,推测这可能与涉及在两价金属离子转运之间的金属吸收、细胞通道或对关键性分子靶 (即DNA聚合酶 )结合的竞争有关。     

维生素E对染镍肺泡巨噬细胞膜脂质过氧化的影响

[目的 ]探讨维生素E拮抗镍所致细胞毒作用及作用机制。 [方法 ]采用体外细胞培养方法 ,观察维生素E对染镍肺泡巨噬细胞膜脂质过氧化产物丙二醛 (MDA)及超氧化物歧化酶 (SOD)活性的影响。 [结果 ]在体外染镍肺泡巨噬细胞培养过程中加入不同浓度的维生素E(2 5、5 0或 10 0 μmol/L)可提高肺泡巨噬细胞内SOD活性 ,具有剂量反应关系。维生素E能显著抑制MDA生成量 ,其中以 5 0和 10 0 μmol/L浓度组作用最为明显。[结论 ]镍可增加细胞脂质过氧化 ,维生素E具有拮抗镍所致细胞毒性的作用 ,可能与其抗氧化功能有关     

不同种类贵金属合金与镍铬合金的金瓷结合强度分析

目的：比较3种贵金属合金和镍铬合金与瓷的金瓷结合强度。方法：通过金瓷界面间的剪切强度测定，观察金铂合金、金钯合金、银钯合金及镍铬合金的金瓷结合强度。结果：不同种类的贵金属合金及镍铬合金间的金瓷结合强度测量值均有差异，镍铬合金的结合强度值最高，金铂次之，银钯再次之，金钯最小。除金—铂合金组与银—钯合金组之间无显著性差异外，其他各组之间都有显著性差异。结论：在本实验条件下贵金属合金结合强度低于镍铬合金，其中金钯合金最低。     

食管支架置入治疗食管狭窄

目的 评价食管支架透视下徒手置入法的价值。方法 采用透视下徒手置入法为49例食管狭窄患者置入国产镍钛热记忆合金支架，对置入效果和操作时间进行观察。结果 患者术后即可进食半流质饮食，呛咳消失。操作时间10-20min25例，20-30min18例，超过30min以上者30min以上者6例。结论 食管内支架透视下徒手置入法成功率高，置入效果和其他置入方法基本相同，是一种安全、有效、操作简便的治疗技术，易于推广。     

Attitude Toward Organ Donation and Transplantation in Veterinary Students: A Multicenter and Stratified Study in Spain

Background

Veterinarians often hold decision-making positions in the public health care system and can therefore influence public opinion about organ donation and transplantation (ODT). The aim of this work was to analyze the attitude of Spanish veterinary students toward ODT, because they may influence public opinion in the future, and to determine the factors that condition it.