A Fast Approach for Predicting Aerodynamic Noise Sources of High-Speed Train Running in Tunnel

The aerodynamic noise of high-speed trains passing through a tunnel has gradually become an important issue.Numerical approaches for predicting the aerodynamic noise sources of high-speed trains running in tunnels are the key to alleviating aerodynamic noise issues.In this paper,two typical numerical methods are used to calculate the aerodynamic noise of high-speed trains.These are the static method combined with non-reflective boundary conditions and the dynamic mesh method combined with adaptive mesh.The fluctuating pressure,flow field and aerodynamic noise source are numerically simulated using the abovemethods.The results showthat the fluctuating pressure,flow field structure and noise source characteristics obtained using different methods,are basically consistent.Compared to the dynamic mesh method,the pressure,vortex size and noise source radiation intensity,obtained by the static method,are larger.The differences are in the tail car and its wake.The two calculation methods show that the spectral characteristics of the surface noise source are consistent.The maximum difference in the sound pressure level is 1.9 dBA.The static method is more efficient and more suitable for engineering applications.

Regenerative Therapeutic Applications of Mechanized Lipoaspirate Derivatives

Autologous adipose tissue is one of the most commonly used fillers.Plastic surgeons are increasingly using it in aesthetic or reconstructive surgery owing to its abundant source,easy availability,and minimal invasiveness.Increasing amount of evidence has shown its reparative ability rather than just filling utility due to the presence of adipose-derived stem cells(ADSCs)that exhibit multipotential differentiation and paracrine characteristics.However,traditional enzymatic isolation of ADSCs is often difficult in clinical settings,limiting its application.Recently,with the development of mechanical techniques for preparation of lipoaspirates,bioactive adipose tissue can be successfully identified and isolated.Such components with therapeutic potential might also be helpful in tissue repair and regeneration.In this article,we introduced several types of mechanized lipoaspirates derivatives(such as emulsified fat,adipose extracellular matrix(ECM),and cell-free extraction)and their applications from bench to bedside.

糖尿病视网膜病变患者全视网膜光凝后角膜上皮基底神经丛和朗格汉斯细胞的改变及其相关性

目的:利用结构拼图观察糖尿病(DM)患者全视网膜光凝(PRP)前后角膜上皮基底神经丛(SNP)和朗格汉斯细胞(LC)的变化,并分析二者的相关性。方法:前瞻性临床研究。选取2019年4─11月就诊于山西省眼科医院准备行PRP治疗且双眼糖尿病视网膜病变Ⅳ期的2型DM患者,选择病情较重的眼为治疗眼,对侧眼为对照眼,分别于PRP治疗前、每次光凝后1周和PRP完成后1个月行角膜共焦显微镜检查,观察涡状结构及其周围2~3 mm区域SNP和LC的变化,并测量涡状区神经纤维长度(NFL)值和LC密度。采用重复测量方差分析比较不同观察时间点LC密度和NFL值,并采用SAS软件的MIXED模型分析重复测量的NFL值和LC密度之间的相关性。结果:共纳入患者49例。治疗眼接受PRP后部分患者出现SNP神经纤维变细,伴有不同程度的涡状区神经结构缺失的神经损伤表现;各观察时间点NFL值总体比较差异有统计学意义(F=8.039,P=0.004),且PRP治疗前NFL值[(15.5±3.7)mm/mm^(2)]与第2次光凝后1周[(15.0±3.5)mm/mm^(2)]、第3次光凝后1周[(13.4±4.3)mm/mm^(2)]和第4次光凝后1周[(13.5±4.1)mm/mm^(2)]比较差异均有统计学意义(均P<0.05)。同时,治疗眼LC密度增加,并以涡状区为中心聚集,成熟LC浸润区伴有SNP神经结构的缺失;各观察时间点LC密度总体比较差异有统计学意义(F=12.350,P<0.001),且PRP治疗前LC密度[(40±54)cells/mm^(2)]与第3次光凝后1周[(79±91)cells/mm^(2)]、第4次光凝后1周[(98±126)cells/mm^(2)]以及PRP完成后1个月[(87±102)cells/mm^(2)]比较差异均具有统计学意义(均P<0.05);相关分析显示治疗眼第4次激光后1周LC密度与其基线水平呈正相关(r=0.674,P<0.001);且重复测量的NFL值与LC密度呈负相关(p=-0.041)。结论:PRP多次光凝可以导致LC密度增加;成熟LC可以导致SNP神经结构破坏。