Thermal shock resistance of thermal barrier coatings modified by selective laser remelting and alloying techniques

Aiming to improve the thermal shock resistance of thermal barrier coatings (TBCs), the plasma-sprayed 7YSZ TBCs were modified by selective laser remelting and selective laser alloying, respectively, in this study. A self-healing agent TiAl₃ was introduced into the 7YSZ TBCs by selective laser alloying to fill cracks during thermal cycling. The thermal shock experiments of the plasma-sprayed, laser-remelted, and laser-alloyed TBCs were conducted by a means of heating and water-quenching method. Results revealed that some segmented microcracks were distributed on the surface of the laser-remelted and the laser-alloyed zones, showing a dense columnar crystal structure. After thermal shock tests, the numbers of segmented microcracks on the laser-remelted coating increased, whereas, in the laser-alloyed condition, some irregular particles formed, leading to the decreased numbers of segmented microcracks. The laser-alloyed coating exhibited the best thermal shock resistance, followed by the laser-remelted condition, with the thermal shock lifetime 3.3 and 2.7 times higher than that of the as-sprayed coating, respectively. On the one hand, both columnar grains and segmented microcracks in the laser-treated zone could effectively improve the strain tolerance of coatings. On the other hand, the oxidation products of TiAl₃ under high-temperature condition could seal the microcracks to postpone the crack connection. Thus, the thermal shock resistance of the laser-treated coatings was significantly improved.     

MCFA alleviate H2O2-induced oxidative stress in AML12 cells via the ERK1/2/Nrf2 pathway

Oxidative stress is an important factor in the occurrence and development of liver disease. Medium-chain fatty acids (MCFAs) have potential antioxidant function, whereas the exact underlying mechanism of MCFA in oxidative injury of hepatocytes remains unclear. In our present study, three different MCFAs, 8-carbon octanoic acid (OA), 10-carbon capric acid (CA), and 12-carbon lauric acid (LA), have been performed to observe their protective action for hepatocyte under the H₂O₂ challenge. The result showed that MCFA treatment significantly increased the cell viability, T-AOC, and expression of antioxidant-related genes in AML12 cells under oxidative stress condition, and reduced reactive oxygen species (ROS) production. Moreover, MCFA treatment significantly increased the protein expression of Nrf2 and the phosphorylation level of ERK1/2; LA treatment significantly promoted the Nrf2 nuclear translocation. With a further test, the rescue ability of MCFA was blocked by treating with the ERK inhibitor U0126. Overall, our data suggested that MCFA treatment has positive impact on protecting AML12 cells against oxidative stress through ERK1/2/Nrf2 pathway.     

Boosted photoelectric cathodic protection exerted by 3D TiO2/AgInS2/In2S3 nanomultijunction for pure copper in NaCl solution

Journal of Applied Electrochemistry - The global annual consumption of marine metal corrosion is a significant challenge to the service life of metals and the development of marine strategies. A...     

Optical fiber multiparameter sensor for real-time monitoring of thermoplastic composites during in situ consolidation process

Temperature and strain are important parameters in the in situ consolidation process of thermoplastic composites and have been monitored based on optical fiber Bragg gratings. A special polyimide fiber grating (PFBG) is used in this article. PFBG can monitor temperatures up to 400°C and strains up to 40,000 με. The wavelengths of the PFBGs are obtained by wavelength demodulation system and fast digital signal processing with field programmable gate array. Temperature and strain in auto fiber placement process of thermoplastic composites are monitored accurately according to wavelengths. During the whole consolidation process, temperatures have been monitored with the accuracy of 0.1°C in the range of 100–250°C and strains have been monitored with the accuracy of 1 με in the range of ?250 to 500 με. The validity and correctness of the results have been validated by the thermocouple and the strain gauge.     

F463L increases the potential of dofetilide on human ether‐a‐go‐go‐related gene (hERG) channels

Mutations in genes related to long QT syndrome (LQTS) is recognized as an independent risk of drug‐induced LQTS. We previously screened a mutation F463L in a Chinese patient with LQT2, syncope, and epilepsy. Here, we planned to illustrate how F463L influences the action of dofetilide on hERG channels. F463L‐hERG plasmids were transfected into the stable Human Embryonic Kidney 293 (HEK293) cells expressing WT‐hERG to generate heterozygous mutant (WT + F463L‐hERG). Whole‐cell patch clamp and laser confocal scanning microscopy were used to evaluate electrophysiological consequences and the membrane distribution of hERG protein. In comparison of WT‐hERG channels exposed to dofetilide, heterozygous F463L‐hERG channels showed a reduction in the density of tail currents when exposed amidarone. F463L‐hERG also altered the action of dofetilide on the gating properties of hERG channels. Images of dofetilide‐treated cells expressing heterozygous F463L showed a severe retention and reduction of protein expression on the membrane compared to WT. In conclusion, dofetilide displays a powerful inhibitory effect on the currents from cells expressing heterozygous F463L, thus showing an additive suppression of currents by F463L with dofetilide.     

基于有限元分析的管道腐蚀缺陷生长预测模型

由于服役环境的影响,管线钢表面不可避免的会出现腐蚀缺陷,腐蚀处会产生应力集中,促进裂纹形核。基于有限元方法建立了用于预测腐蚀缺陷形貌发展的应力和电化学多物理场耦合模型。在模型中采用了变形几何和动态网格技术,用以研究X70管线钢在海泥模拟溶液中的应力腐蚀行为和腐蚀形貌随时间发展情况。结果表明,机械⁃电化学效应对应力腐蚀裂纹的形核具有重要作用;较小的腐蚀缺陷宽度使应力集中程度加大,电极电位负移,腐蚀速率增大;随着操作压力增大,腐蚀缺陷底部的管壁出现大面积的高应力集中区域,因腐蚀导致的金属损失面积增大。     

中国公铁两用桥主桥结构体系分析与展望

中国公铁两用桥发展至今已有近80年的历史,从早期跨径小、结构受力简单的梁式体系发展到目前大跨径的拱式体系以及大跨径、超大跨径的斜拉、悬索体系等。通过收集中国已建和在建的以上4种结构体系的公铁两用桥相关资料,对中国4种结构体系的公铁两用桥主桥主梁结构、基础以及其他结构部分在结构设计、施工工艺、材料性能上的发展趋势进行了分析。分析发现：4种结构体系公铁两用桥主桥主梁结构设计中的主桁形式、桥面系、联结系在结构上由繁至简、由离散拼装至整体栓焊;主桁桁式在力学特性上与各结构体系公铁两用桥主梁受力特点相辅相成,充分发挥了材料的性能和结构的受力特点,主梁施工工艺趋于系统化、高效化、经济化,其材料性能趋于优质化;基础的类型没有明显变化,但其施工方法实现了自我创新,材料性能趋于优质化;拱式体系公铁两用桥主桥主拱的结构设计趋于新型化,施工工艺趋于复杂化,在材料的选择上趋于科学和经济化;斜拉和悬索体系公铁两用桥除主梁和基础部分外,其他部分结构的设计趋于科学化,施工趋于经济化、智能化,材料性能趋于优质化。     

海上稠油低温热化学机理研究与应用

稠油油田存在汽窜、含水率上升、低产低效井等问题。针对存在问题,提出了低温热化学技术,利用自主研发的适应于海上稠油油田高效开发化学体系-磺酸盐类化学体系L⁃B,协同低温蒸汽的热作用,达到降本增效并提高驱油效率的目的。该体系的静态洗油效率达28.7%。在56 ℃与原油的界面张力为0.086 mN/m,相比于原油与地层水的界面张力降低了99.3%。120 ℃驱油效率可达65.00%,相比于同等温度蒸汽驱提高了8.50%,达到了200 ℃的驱油效果。该技术在渤海某油田应用后,单井最高日产油达32 m3,提高了52.4%,对海上稠油油田提高原油采收率研究具有一定的指导和借鉴意义。     

气动软体驱动器的设计

根据人手指外骨骼关节结构,提出硅胶多腔体仿人柔性关节,设计了一种用于手部康复机器人的气动软体驱动器,详细阐述了驱动器的制作流程。采用Abaqus软件对软体驱动器进行有限元仿真,给出不同气压下的仿真图形。仿真结果表明,提出的软体驱动器的理论模型与实验数据基本吻合,相对于其他结构,整体的稳定性,抓取能力更强,为以后仿人柔性机械手的应用提供了支撑。