Current Status of Angiogenic Cell Therapy and Related Strategies Applied in Critical Limb Ischemia

Critical limb ischemia (CLI) constitutes the most severe form of peripheral arterial disease (PAD), it is characterized by progressive blockade of arterial vessels, commonly correlated to atherosclerosis. Currently, revascularization strategies (bypass grafting, angioplasty) remain the first option for CLI patients, although less than 45% of them are eligible for surgical intervention mainly due to associated comorbidities. Moreover, patients usually require amputation in the short-term. Angiogenic cell therapy has arisen as a promising alternative for these “no-option” patients, with many studies demonstrating the potential of stem cells to enhance revascularization by promoting vessel formation and blood flow recovery in ischemic tissues. Herein, we provide an overview of studies focused on the use of angiogenic cell therapies in CLI in the last years, from approaches testing different cell types in animal/pre-clinical models of CLI, to the clinical trials currently under evaluation. Furthermore, recent alternatives related to stem cell therapies such as the use of secretomes, exosomes, or even microRNA, will be also described.     

模拟地面集输环境下温度对2205双相钢均匀腐蚀及点蚀行为的影响

针对油气集输管线在CO2和含高浓度的Cl-地层水环境中易发生腐蚀失效的问题，通过腐蚀失重试验和电化学测试分析，研究了2205双相不锈钢在高分压CO2+高矿化度+高浓度Cl-地层水集输管线环境中的腐蚀行为。结果表明:在模拟油田集输管线环境中，升温引起的2205双相不锈钢的均匀腐蚀速率基本不变，整体表现为轻度腐蚀，但由于Cl-的存在，2205双相钢在50 ℃和70 ℃时出现明显的点蚀坑形貌；2205双相钢在3种测试温度下的阳极极化曲线存在明显的钝化区，随着温度的升高，2205双相钢的点蚀电位先升高、再下降，在30~50 ℃，存在一个临界点蚀温度CPT；交流阻抗图谱在50 ℃和70 ℃分别表现出了点蚀诱导期和点蚀发展期的特征。     

高压天然气多孔节流效应及冲蚀特性分析

基于欧拉 拉格朗日多相流模型方法，采用RNG k ε湍流模型和Sutherland viscosity law可压缩流体黏度修正模型及改进的冲蚀模型，对高压天然气单孔和多孔节流过程进行数值模拟。通过高压天然气单孔节流数值模拟质量流率变化规律，与理论计算结果对比，验证了所采用的模型和计算方法的准确性，并考察了高压天然气流经单孔和多孔突缩结构的不同节流效应及冲蚀特性。计算结果表明，天然气流经多孔固定节流油嘴降压后，体积膨胀形成的最高流速值明显低于单孔固定油嘴，同时多孔均匀射流减少了单孔射流形成的卷吸冲蚀损伤，并在多股射流下的搅混作用下，冷核心能迅速混合，在后续油嘴腔体内更易实现压力回升和速度稳定现象，相比单孔节流可以有效地抑制冲蚀损伤及天然气水合物生成几率。     

Nb和时效时间对热轧中锰TRIP钢中P偏聚的影响

热轧态中锰TRIP钢首先经650 ℃退火2 h,随后在550 ℃进行等温时效热处理,采用场发射扫描电镜(FE-SEM)研究该钢中P的偏聚和时效析出行为的变化情况。结果表明,中锰TRIP钢中P在晶界的偏聚是一种非平衡偏聚现象,临界时间约为50 h,与理论计算结果48 h较为吻合。在局部偏聚区域内,C与P存在共偏聚的关系,即P偏聚量高的地方,C含量也高。而合金元素Nb具有抑制P偏聚的效果,在20~70 h时效时间内,可以相对降低6.57%~19.5%的最大P偏聚量。根据电子背散射衍射(EBSD)菊池线分析,P偏聚量低于2.28at%时,P为固溶状态,高于2.28at.%时,P为析出状态。     

夹杂物对工程机械用钢Q345FCA疲劳寿命的影响

采用QBWP-6000J型简支梁旋转弯曲疲劳试验机测定了高疲劳寿命工程机械用钢Q345FCA的疲劳寿命;采用扫描电镜(SEM)对疲劳断口形貌进行了观察,并用附带的能谱仪(EDS)寻找断口上的夹杂物;借助夹杂物自动分析系统对钢中的夹杂物进行了分析。通过对试验数据的分析,计算得出了Q345FCA钢和Q345钢夹杂物的表面临界尺寸、次表面临界尺寸和内部临界尺寸。结果表明,Q345FCA钢的疲劳极限为273 MPa,Q345钢的疲劳极限为266 MPa。Q345FCA钢和Q345钢中夹杂物尺寸均小于临界夹杂物尺寸,且断口形貌显示所有疲劳断裂均不是由夹杂物所引起,夹杂物不是疲劳源。     

New insight to the oxidation kinetics of silicon-containing steel at high temperature

This study investigated the oxidation kinetics of silicon-containing steel at 1150–1300 °C using a Simultaneous Thermal Analyzer under atmospheric conditions similar to that of an industry reheating furnace. There is a critical time point for the oxidation kinetics at an oxygen concentration of 4·0 vol.-%., following which the oxidation rate constant increases with the increasing oxidation temperature. The model coefficient A in the kinetic oxidation equation was found to be constant. However, before the critical time point, the oxidation rate constant remained unchanged; the model coefficient A decreased with the increasing temperature. Therefore, the kinetic model of silicon-containing steel for isothermal oxidation was observed to be a modified one on the basis of the experimental data. In addition, the critical time point was prolonged with the increasing isothermal oxidation temperature. Moreover, the oxidation activation energy of the tested silicon-containing steel was 366·16 kJ mol^?1.     

原油包裹体中芳香烃组分类型与成熟度关系——以三肇凹陷扶余油层为例

为了明确油包裹体中芳香烃组分与原油成熟度的关系，基于原油的荧光性，利用单个包裹体组分无损分析的荧光光谱方法，对松辽盆地三肇凹陷扶余油层油包裹体荧光光谱进行了定量化描述。首先获取了储层油包裹体荧光颜色类型，然后获得了单个油包裹体荧光光谱图，并对比标准芳香烃在波长为365 nm单色光激发下的荧光光谱主峰波长特征值，最终划分了油气充注幕次及不同幕次油包裹体芳香烃组分类型。研究结果表明：扶余油层发育黄色、黄绿色、蓝绿色和蓝色4种荧光颜色油包裹体，代表了不同成熟度的油气充注。其中第1幕黄色荧光油包裹体主峰对应的波长（λ_max）为576.0~584.5 nm，为低成熟度油充注；第2幕黄绿色荧光油包裹体λ_max为528.7~546.3 nm，为中等成熟度油充注；第3幕蓝绿色荧光油包裹体λ_max为491.6~516.1 nm，为中等成熟度油充注；第4幕蓝色荧光油包裹体λ_max为440.6~456.5 nm，为高成熟度油充注。综合判定得出，三肇凹陷扶余油层在地质历史时期经历了4幕油气充注。油包裹体中芳香烃组分主要有十环芳香烃、并四苯，其次含有红荧烯，并含有少量的胆蒽、蒽；储层油包裹体总体表现出小分子量芳香烃少、大分子量芳香烃多的特征，说明储层包裹体中原油以低-中等成熟度原油为主。通过拟定油包裹体荧光光谱特征与芳香烃组分关系，从而为原油芳香烃组分类型及成熟度研究提供一定依据。     

一种波长调制干涉仪光强实时反馈控制系统

提出了一种实时反馈控制系统,保证波长调制干涉仪的激光光强在波长调谐过程中的稳定性,以减小波长调制干涉仪因激光光强的波动产生的相位误差。该控制系统由光电探测器、数据采集卡、光电调幅器和控制软件等组成。实验结果表明,该系统的响应速度超过了干涉仪获取干涉图的速度,不仅能够稳定输出理想的光强值,而且还提高了干涉仪的测量精度。     

Propagation of surface cracks on beam blank in the mould during continuous casting

ABSTRACT

We focus on crack propagation to investigate surface cracks in the mould during continuous casting, based on the crack initiation mechanism proposed in previous studies. The temperature and stress data of a solidified shell were extracted, and an extended finite element model based on the continuous damage theory of elastic–plastic materials was developed to simulate surface crack propagation. The results showed that, in the cracked area, stress concentration occurred at the crack tip, and the element split open and the crack propagated when the maximum principal stress in the stress concentration area reached the critical value. Prefabricated cracks in the fillet and web mainly developed into longitudinal cracks in the mould. The theoretical mechanism of this study was found to be the same as the crack propagation mechanism observed during the actual production of beam blanks. Thus, this study reveals the theoretical principle of crack initiation and propagation and can provide theoretical guidance for controlling surface cracks during beam blank continuous casting.