溶胶-凝胶微波加热合成PbZr_(0.52)Ti_(0.48)O_3前驱体

以硝酸铅、硝酸锆、四氯化钛、柠檬酸为原料,用溶胶-凝胶法制备出凝胶,在100℃下烘干,然后用微波炉加热,合成了PbZr0.52Ti0.48O3前驱体。讨论了微波合成参数对粉体晶相和晶体粒度的影响。用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对制备的粉体进行了表征。结果表明,溶胶-凝胶结合微波加热法可以在较短的时间内制得PbZr0.52Ti0.48O3粉体,且晶形发育比常规加热更完善。微波120℃加热20min,可得到纯相的PbZr0.52-Ti0.48O3前驱粉。     

2,6-二氯-3-氰基-4-甲基吡啶的合成及应用

2,6-二氯-3-氰基-4-甲基吡啶是制备染料的重要中间体,本文对2,6-二氯-3-氰基-4-甲基吡啶合成路线及其优缺点进行评述,并对其应用进行了介绍。     

Microstructure and properties of WC reinforced Ni-based composite coatings with Y2O3 addition on titanium alloy by laser cladding

ABSTRACT

In this study, WC reinforced Ni-based composite coatings with Y₂O₃ addition were deposited on Ti-6Al-4V titanium substrate by laser cladding. The phases, microstructure, microhardness and wear resistance of the composite coatings were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, microhardness tester and wear tester. The results showed that good metallurgical bonding was achieved between the composite coatings and substrate. The phases mainly were γ-Ni, TiC, TiB₂, Ni₃B, M₂₃C₆ and WC. Most of the WC was dissolved in small pieces of WC during the laser cladding process. The microhardness of the composite coatings was about 3 times that of the titanium substrate and the wear resistance of the composite coatings had a significant increase.     

Harnessing the scientific synergy of welding and additive manufacturing

ABSTRACT

Additive manufacturing (AM) of metallic materials and welding share many similarities in their physical processes and the way the microstructure and properties of the products evolve. This synergy can be a powerful driver for the scientific and technological advancements of both these important technologies for the benefit of all people. Science and Technology of Welding and Joining provides a forum for the exchange of emerging scientific and technological advancements in AM. This special issue of the journal highlights the current research in the AM processes, and the microstructure and properties of metallic components. Furthermore, it identifies some of the current challenges and opportunities for the future.     

Friction and wear reductions in fluorinated plain and fully formulated oils through enhanced heating time using moderate loading under boundary lubrication conditions

The use of fluorinated mix catalyst (titanium fluoride: TiF₃ + iron fluoride: FeF₃) with polytetrafluoroethylene: PTFE in engine oil is increasingly a strategy to improve fuel economy and component durability to simultaneously provide low friction and excellent wear protection. The influence of these additives shows promising results during load bearing capacity testing and long‐term durability experiments. This paper addresses the enhancement of friction and wear performances of 0.1% and 0.05% phosphorus plain zinc dialkyl dithiophosphate (ZDDP) oil and fully formulated engine oil when heated to 100°C for specific time under thermal and tribological conditions for moderate pressure loading (1.9 GPa Hertzian pressure or 180 N) which simulate the cold start of a car under 700 rpm rotational speed or the valve trains loading where most of the ZDDP are applied. Tests were performed in a ball on cylinder tribometer under boundary lubrication conditions. Surface analyses were carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results showed that the anti‐wear additives (2 wt. % PTFE + 0.5 wt. % FeF₃ + .5 wt. % TiF₃) provided excellent wear protection to 0.1% phosphorus plain and fully formulated oil when cylinder is immersed in the desired lubricant and heated for a predetermined time but performed poorly in 0.05% phosphorus fully formulated oil under the same conditions. The transform of anti‐wear coated material to the worn surfaces, which was a function of the anti‐wear performance of additives, was shown to have an influence on friction performance. The wear reducing effect, which was observed in fluorinated additives tribological tests, indicated a positive contribution and good tribofilm formations. Copyright © 2016 John Wiley & Sons, Ltd.     

救生机器人推进器的3维反问题设计与性能校验

针对水上救生机器人难以实现快速稳定航行的问题,采用3维反问题设计理论对机器人推进器进行几何设计并对相关参数进行匹配,在合理假设条件下,将喷水推进泵内的有旋流方程进行有效分解获得周向平均流动方程和周期性脉动流动方程。使用速度矩沿流线的分布来控制叶片的载荷,运用计算流体力学对所设计的喷水推进泵进行水力性能校验,结果表明：在毂径比较大等特定条件约束下,喷水推进泵的水力效率达到80.38%,并且在较宽的流量范围内保持高效,叶轮表面压力沿轴向分配合理,没有局部低压区,叶轮推力满足预期性能,验证了设计思路和参数配置的正确性。     

基于unity3D AR 体感游戏的设计与实现

针对传统游戏方式存在影响人身心健康的弊端,设计基于kinect2.0 体感设备和 unity3D 2017.4.3 开发AR 体感游戏。介绍游戏总体设计,给出开发流程图,详细阐述游戏开发过程中的关键技术、方法和插件,程序首次大 胆地将人物体感过程中的自拍照片按照Sisley 油画风格和多尺度弧形笔刷风格进行处理。实验结果表明：该游戏运 行流畅,功能和创新达到设计要求,能让玩家在娱乐中保留美好油画回忆。     

双轮廓仪金属增材制造工件表面3 维重建技术

为解决金属增材制造的零件易出现变形的问题,开展基于双轮廓仪的变形检测技术研究。以激光三角测 量法为测量核心方法,通过点云数据拼接处理,完成了工件表面形貌的3 维重建。实验验证结果表明：该系统能达 到的测量分辨率为2 μm,可为金属增材制造加工过程的变形检测技术提供一种新的检测手段。     

磷酸腺苷依赖的蛋白激酶在自噬通路中作用的研究进展

近年来,磷酸腺苷依赖的蛋白激酶（AMPK、5′-AMP-activated protein kinase）在细胞自噬（autophagy）中的研究已成为热点之一。自噬是一个多步骤复杂的过程并对能量敏感,AMPK 作为能量感受器对营养敏感且在自噬的过程中发挥关键酶的作用。本文主要介绍了细胞自噬以及 AMPK 通过 mTOR（mammalian target of rapamycin）、p53、PI3K 3条通路影响自噬通路的过程。     

丙泊酚对急性肺损伤大鼠肺泡Ⅱ型上皮细胞凋亡及 PI3K／Akt 通路的影响

目的：探讨丙泊酚的肺保护作用及其可能作用机制。方法采用尾静脉注射内毒素建立急性肺损伤模型,丙泊酚和 LY294002同样经过尾静脉给药。将 Wistar 大鼠随机分入实验对照组（C 组）、脂多糖组（L 组）、脂多糖＋丙泊酚组（LP 组）和 LY294002组（LY 组）。每组16只,且每组随机选取8只进行肺泡Ⅱ型上皮细胞（ATⅡ）的分离。给药前及开始后第3、6和12 h 测定动脉血氧分压（PaO2）,实验结束后观察肺湿／干重（W／D）比值、肺组织病理学检查并进行肺损伤轻重程度评分,同时观察各组大鼠 ATⅡ Akt 活性、Bax 蛋白表达及凋亡率。结果实验前各组 PaO2无明显差异,注射 LPS 后 L 组 PaO2持续下降,和 C 组相比其 PaO2显著降低（P ＜0．05）。实验结束后 L组和 C 组相比其 W／D 比值、肺组织病理学检查评分、ATⅡBax 蛋白表达及凋亡率显著升高（P ＜0．05）,而 ATⅡAkt 活性显著降低（P ＜0．05）。而 LP 组和 L 组相比 W／D 比值、肺组织病理学检查评分、ATⅡBax 蛋白表达及凋亡率显著降低（P ＜0．05）,而 PaO2和 ATⅡAkt 活性显著升高（P ＜0．05）。而 LY 组加入 LY294002后明显抑制丙泊酚以上保护作用。结论丙泊酚具有肺保护作用,且该作用可能与其通过激活 PI3K／Akt 通路而抑制 ATⅡ的过度凋亡作用相关。