神经免疫炎症在帕金森病中的研究

帕金森病(Parkinson disease,PD)是一种常见的神经系统退行性疾病,多发于中老年人,60岁以上的人群患病率超过1%[1]。其典型的病理特征为α-突触核蛋白(α-synuclein,α-syn)错误折叠聚集形成路易氏小体(Lewy body,LB)和路易神经突(Lewy neurite,LN),以及中脑黑质致密部(substantia nigra pars compacta,SNpc)中多巴胺能神经元的明显减少。最近十年的研究表明,神经免疫炎症在PD发病机理中起着至关重要的作用。有研究发现,炎症有诱导和/或加重神经系统退行性疾病如PD症状的作用。

Effect of scanning speeds on electrochemical corrosion resistance of laser cladding TC4 alloy

In order to study the effect of scanning speed on the electrochemical corrosion resistance of laser cladding TC4 alloy in artificial seawater, the x-ray diffraction analysis, microstructure of cross-section, microhardness variation, and impedance spectrum have been studied in comparison with the TC4 titanium alloy. The results show that the main phase of cladding coating is α-Ti, and the change of scanning speed has no obvious effect on it; therefore, the supersaturated α-Ti solid solution is formed, and the acicular α martensite is obtained. As the scanning speed increases, the microstructure of cladding coating is orthogonal basket-weave, the crystal surface spacing decreases, and the average microhardness of laser cladding TC4 alloy slightly increases. When the scanning speed increases to 10 mm/s, the microhardness is about 14.71%higher than that of the substrate, and the electrochemical corrosion resistance of laser cladding TC4 alloy is also improved,which is about 2.48 times more than the substrate. Grain refinement has a great effect on enhancing the anti-electrochemical corrosion.

送粉式激光增材制造TC4钛合金熔覆层组织及电化学腐蚀行为的研究

采用激光增材制造(LDM)技术在TC4钛合金基体表面制备了TC4钛合金熔覆层,研究了不同扫描速率下制备的熔覆层的组织、显微硬度以及其在H_2SO_4溶液中的抗电化学腐蚀性能。结果表明:熔覆层的主要物相为α-Ti,且在β晶界附近生成了细针状α′马氏体,组织呈正交状网篮结构;随着扫描速率增大,熔覆层的平均显微硬度先增大后减小,腐蚀电流密度先降低后升高,电荷转移电阻先增大后减小,即其耐蚀性先增强后减弱;当扫描速率为10 mm/s时,熔覆层具有最大的平均显微硬度(390 HV)、最小的腐蚀电流密度(1.2337μA·cm^(-2))、最大的电荷转移电阻(11500Ω·cm^(-2)),此时的熔覆层具有较好的抗电化学腐蚀性能。