Hydrodynamic Instability Analysis of the Axial Flow Pump in an Ethylene Polymerization Loop Reactor

The hydrodynamic instability of the axial flow pump in a loop reactor has long been a troubling issue to be solved in the polyethylene industry due to the lack of a better mechanismic understanding.Generally,the instability of an axial flow pump can be reflected by the fluctuation of the pump head.In this study,the transient computational fluid dynamics(CFD)simulation is adopted to study the hydrodynamic instability of the axial flow pump used in an ethylene polymerization loop reactor.The resul...     

HSPA4 Is a Biomarker of Placenta Accreta and Enhances the Angiogenesis Ability of Vessel Endothelial Cells

Placenta accreta spectrum (PAS) accounts for 7% of maternal mortality and is associated with intraoperative and postoperative morbidity caused by massive blood loss, infection, and adjacent organ damage. The aims of this study were to identify the protein biomarkers of PAS and to further explore their pathogenetic roles in PAS. For this purpose, we collected five placentas from pregnant subjects with PAS complications and another five placentas from normal pregnancy (NP) cases. Then, we enriched protein samples by specifically isolating the trophoblast villous, deeply invading into the uterine muscle layer in the PAS patients. Next, fluorescence-based two-dimensional difference gel electrophoresis (2D-DIGE) and MALDI-TOF/MS were used to identify the proteins differentially abundant between PAS and NP placenta tissues. As a result, nineteen spots were determined as differentially abundant proteins, ten and nine of which were more abundant in PAS and NP placenta tissues, respectively. Then, specific validation with western blot assay and immunohisto/cytochemistry (IHC) assay confirmed that heat shock 70 kDa protein 4 (HSPA4) and chorionic somatomammotropin hormone (CSH) were PAS protein biomarkers. Further tube formation assays demonstrated that HSPA4 promoted the in vitro angiogenesis ability of vessel endothelial cells, which is consistent with the in vivo scenario of PAS complications. In this study, we not only identified PAS protein biomarkers but also connected the promoted angiogenesis with placenta invasion, investigating the pathogenetic mechanism of PAS.     

Molecular and Physiological Responses of Citrus sinensis Leaves to Long-Term Low pH Revealed by RNA-Seq Integrated with Targeted Metabolomics

Low pH-induced alterations in gene expression profiles and organic acids (OA) and free amino acid (FAA) abundances were investigated in sweet orange [Citrus sinensis (L.) Osbeck cv. Xuegan] leaves. We identified 503 downregulated and 349 upregulated genes in low pH-treated leaves. Further analysis indicated that low pH impaired light reaction and carbon fixation in photosynthetic organisms, thereby lowering photosynthesis in leaves. Low pH reduced carbon and carbohydrate metabolisms, OA biosynthesis and ATP production in leaves. Low pH downregulated the biosynthesis of nitrogen compounds, proteins, and FAAs in leaves, which might be conducive to maintaining energy homeostasis during ATP deprivation. Low pH-treated leaves displayed some adaptive responses to phosphate starvation, including phosphate recycling, lipid remodeling, and phosphate transport, thus enhancing leaf acid-tolerance. Low pH upregulated the expression of some reactive oxygen species (ROS) and aldehyde detoxifying enzyme (peroxidase and superoxidase) genes and the concentrations of some antioxidants (L-tryptophan, L-proline, nicotinic acid, pantothenic acid, and pyroglutamic acid), but it impaired the pentose phosphate pathway and V_E and secondary metabolite biosynthesis and downregulated the expression of some ROS and aldehyde detoxifying enzyme (ascorbate peroxidase, aldo-keto reductase, and 2-alkenal reductase) genes and the concentrations of some antioxidants (pyridoxine and γ-aminobutyric acid), thus disturbing the balance between production and detoxification of ROS and aldehydes and causing oxidative damage to leaves.     

高强聚烯烃静态断裂过程银纹区的性能1.HDPE

为了观察分析高密度聚乙烯(HDPE)的银纹区性能,对两种HDPE全切痕试样分别进行了速率为0.1 mm/min,0.5 mm/min,1 mm/min,5 mm/min,20 mm/min和50 mm/min的拉伸测试。基于对静态断裂过程应力-位移数据的分析处理,结果表明,HDPE的屈服应力随着拉伸速率增大;高应力时两种HDPE均存在常临界位移控制其银纹断裂;HDPE2480银纹微纤的稳定性较大,材料韧性较好。HDPE静态拉伸断面显微结构显示,HDPE2480的银纹微纤尺寸大于HDPE4801,导致两者断面弧形巢尺寸和弧形巢内粗糙度的不同。     

CSA电热类厨用小家电的产品结构及测试要求

CSA是北美权威认证机构之一,为世界各地厂商出口北美的产品提供认证服务,通过CSA认证的产品均可印上相应的CSA认证标志,标识该产品符合CSA标准的要求.     

围挡式洁净区的单向流特性研究

通过实验分析围挡式洁净区的3个特性指标，即：流线平行度、乱流度和下限风速，并指出其应用价值和市场前景。     

热处理对MIM薄膜二极管Ta2O5绝缘膜微结构及其I-U特性的影响

制备了一种用于有源矩阵液晶显示、具有对称结构的MIM薄膜二极管 ,其中Ta2 O5膜采用溅射 /阳极氧化两步法工艺制成。对绝缘膜进行真空热处理 (一步热处理 )和经真空热处理后再进行大气热处理 (真空 /大气两步热处理 )。用原子力显微镜和透射电子显微镜分析了Ta2 O5膜的微结构 ,测试了MIM薄膜二极管的I U特性曲线。讨论了热处理对Ta2 O5绝缘膜微结构和MIM薄膜二极管I U特性的影响 ,并指出了MIM薄膜二极管I U特性和绝缘膜微结构之间的关系     

一种新型旋翼／机身隔振装置及其性能分析

从降低旋翼动载荷向机身传递的基本目标出发,研究了新型旋翼／机身隔振装置的基本设计思想,给出了设计原则及方法,介绍了反共振装置、波纹板的设计及试验的关键。台架试验表明：该装置能同时实现对桨毂五个交变力素的隔离,其隔振效率及重要指标均达到设计要求