Influence of Fine Grains on the Bending Fatigue Behavior of Two Implant Titanium Alloys

By means of the ultrasonic surface impact (amplitude of 30 μm, strike number of 48,000 times/mm²), nanograins have been achieved in the surfaces of both Ti6Al4V(TC4) and Ti3Zr2Sn3Mo25Nb(TLM) titanium alloys, mainly because of the dislocation motion. Many mechanical properties are improved, such as hardness, residual stress, and roughness. The rotating–bending fatigue limits of TC4 and TLM subjected to ultrasonic impact are improved by 13.1% and 23.7%, separately. Because of the bending fatigue behavior, which is sensitive to the surface condition, cracks usually initiate from the surface defects under high stress amplitude. By means of an ultrasonic impact tip with the size of 8 mm, most of the inner cracks present at the zone with a depth range of 100~250 μm in the high life region. The inner crack core to TC4 usually appears as a deformed long and narrow α-phase, while the cracks in TLM specimens prefer to initiate at the triple grain boundary junctions. This zone crosses the grain refined layer and the deformed coarse grain layer. With the gradient change of elastic parameters, the model shows an increase of normal stress at this zone. Combined with the loss of plasticity and toughness, it is easy to understand these fatigue behaviors.     

Quantile regression and empirical likelihood for the analysis of longitudinal data with monotone missing responses due to dropout,with applications to quality of life measurements from clinical trials

The analysis of quality of life (QoL) data can be challenging due to the skewness of responses and the presence of missing data. In this paper, we propose a new weighted quantile regression method for estimating the conditional quantiles of QoL data with responses missing at random. The proposed method makes use of the correlation information within the same subject from an auxiliary mean regression model to enhance the estimation efficiency and takes into account of missing data mechanism. The asymptotic properties of the proposed estimator have been studied and simulations are also conducted to evaluate the performance of the proposed estimator. The proposed method has also been applied to the analysis of the QoL data from a clinical trial on early breast cancer, which motivated this study.     

知识点模块网格化模型在肾内科实习生带教中的应用

目的 运用知识点模块网格化构建带教模型，观察其在肾内科实习生中的应用效果。方法 根据《内科学》（第八版）肾内科教学大纲要求，结合肾内科病房常见病、多发病的临床特点，精心挑选相关知识点，以理论为支撑点，以服务于实习带教工作为靶目标，各个知识点之间有临床的关联性，最终形成网格化的诊治分 析模型。将血尿、蛋白尿、高血压、水肿、肾小球滤过率为切入点，设定肾病综合征、系统性红斑狼疮、糖尿病肾病和急、慢性肾功能衰竭为临床知识必须掌握点，从病史、症状、体征和实验室检查几方面来培养实习生的诊疗思维，并通过知识点来关联疾病的诊治，从而帮助他们在有限的肾内科实习期间尽可能掌握肾内科临床知识。结果 本研究开展一年以来，对于来肾内科轮转的51 名实习生进行了模块网格化模型训练，实习生普遍反映该模型有很好的学习效果，让他们了解了肾内科临床重点，并能和理论学习的知识点有机融合在一起，开阔了实习生的诊疗视野，也便于对其他科知识点的学习。结论 基于知识点模块网格化，构建模型在肾内科实习生中有很好的带教作用，学生接受肾内科知识点的记忆增强，并能进一步推广到内科其他内容的实习带教中。     

Cardiac Denervation for Arrhythmia Treatment with Transesophageal Ultrasonic Strategy in Canine Models

Stellate ganglion (SG) modification has been investigated for arrhythmia treatment. In this study, transesophageal SG imaging and intervention were explored using a homemade 30F integrated focused ultrasonic catheter in healthy mongrel canines in vivo. Anatomic details of SGs were ultrasonically imaged and evaluated. SG had a heterogeneous echoic structure and characteristic profiles sketched by hyper-echoic outlines in an ultrasonogram. Left SGs in the experimental group were successfully ablated through the esophagus under ultrasonic guidance provided by the catheter itself. Two weeks after the ablation, the QT and QTc of the experimental group decreased compared with those of the sham group and at baseline (both p values < 0.001). Histologic examination revealed that left SGs were destroyed. No major complications were observed. This approach may be further explored as a method for ganglia remodeling evaluation and as a strategy of ganglia modification for arrhythmia and for other diseases.