Regulation Mechanism of Novel Thermomechanical Treatment on Microstructure and Properties in Al-Zn-Mg-Cu Alloy

Scanning electron microscopy, transmission electron microscopy, tensile test, exfoliation corrosion test, and slow strain rate tensile test were applied to investigate the properties and microstructure of Al-Zn-Mg-Cu alloy processed by final thermomechanical treatment, retrogression reaging, and novel thermomechanical treatment (a combination of retrogression reaging with cold or warm rolling). The results indicate that in comparison with conventional heat treatment, the novel thermomechanical treatment reduces the stress corrosion susceptibility. A good combination of mechanical properties, stress corrosion resistance, and exfoliation corrosion resistance can be obtained by combining retrogression reaging with warm rolling. The mechanism of the novel thermomechanical treatment is the synergistic effect of composite microstructure such as grain morphology, dislocation substructures, as well as the morphology and distribution of primary phases and precipitations.     

冗余捷联惯组故障诊断的奇异值分解新方法*

冗余捷联惯组故障诊断奇异值分解法由于缺少单位化、阈值偏大和隔离策略有缺陷,导致漏警率偏高、误隔离率偏高且无法隔离负向故障。在分析Shim法原理的基础上,采用改进的解耦矩阵、新的故障隔离函数包含单位化和取模的运算,并且将故障检测和隔离分步实施。对改进方法进行蒙特卡洛数字仿真,仿真试验结果表明:新方法克服了Shim法的缺点,具有更高的正检率、更低的误隔离率。尤其对于发生负向故障的器件,改进方法能得到约99%的隔离率。新方法为冗余捷联惯组故障诊断提供一种新思路。     

Porous polyurethane foam for use as a particle collection substrate in a nanoparticle respiratory deposition sampler

Porous polyurethane foam was evaluated to replace the eight nylon meshes used as a substrate to collect nanoparticles in the Nanoparticle Respiratory Deposition (NRD) sampler. Cylindrical (25 mm diameter by 40 mm deep) foam with 100 pores per inch was housed in a 25-mm-diameter conductive polypropylene cassette cowl compatible with the NRD sampler. Pristine foam and nylon meshes were evaluated for metals content via elemental analysis. The size-selective collection efficiency of the foam was evaluated using salt (NaCl) and metal fume aerosols in independent tests. Collection efficiencies were compared to the nanoparticulate matter (NPM) criterion and a semi-empirical model for foam. Changes in collection efficiency and pressure drop of the foam and nylon meshes were measured after loading with metal fume particles as measures of substrate performance. Substantially less titanium was found in the foam (0.173 µg sampler^?1) compared to the nylon mesh (125 µg sampler^?1), improving the detection capabilities of the NRD sampler for titanium dioxide particles. The foam collection efficiency was similar to that of the nylon meshes and the NPM criterion (R² = 0.98, for NaCl), although the semi-empirical model underestimated the experimental efficiency (R² = 0.38). The pressure drop across the foam was 8% that of the nylon meshes when pristine and changed minimally with metal fume loading (～19 mg). In contrast, the pores of the nylon meshes clogged after loading with ～1 mg metal fume. These results indicate that foam is a suitable substrate to collect metal (except for cadmium) nanoparticles in the NRD sampler.

Copyright © 2016 American Association for Aerosol Research     

Alisertib Induces Cell Cycle Arrest,Apoptosis, Autophagy and Suppresses EMT in HT29 and Caco-2 Cells

Colorectal cancer (CRC) is one of the most common malignancies worldwide with substantial mortality and morbidity. Alisertib (ALS) is a selective Aurora kinase A (AURKA) inhibitor with unclear effect and molecular interactome on CRC. This study aimed to evaluate the molecular interactome and anticancer effect of ALS and explore the underlying mechanisms in HT29 and Caco-2 cells. ALS markedly arrested cells in G₂/M phase in both cell lines, accompanied by remarkable alterations in the expression level of key cell cycle regulators. ALS induced apoptosis in HT29 and Caco-2 cells through mitochondrial and death receptor pathways. ALS also induced autophagy in HT29 and Caco-2 cells, with the suppression of phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), but activation of 5′ AMP-activated protein kinase (AMPK) signaling pathways. There was a differential modulating effect of ALS on p38 MAPK signaling pathway in both cell lines. Moreover, induction or inhibition of autophagy modulated basal and ALS-induced apoptosis in both cell lines. ALS potently suppressed epithelial to mesenchymal transition (EMT) in HT29 and Caco-2 cells. Collectively, it suggests that induction of cell cycle arrest, promotion of apoptosis and autophagy, and suppression of EMT involving mitochondrial, death receptor, PI3K/Akt/mTOR, p38 MAPK, and AMPK signaling pathways contribute to the cancer cell killing effect of ALS on CRC cells.     

Genipin cross-linked chitosan hydrogel for the controlled release of tetracycline with controlled release property,lower cytotoxicity,and long-term bioactivity

To realize the controlled release property, lower cytotoxicity, and long-term bioactivity of tetracycline, the chitosan hydrogel had been prepared using genipin as the cross-linker and the tetracycline was in situ encapsulated. The formation process and strength of hydrogel were studied by rheological analysis, and the microtopography was observed by scanning electron microscope. It was found that the amount of genipin could modulate the physical property of the hydrogel. For in vitro release and antibacterial assays, the hydrogel could controllably release tetracycline and keep its bioactivity for a long time. The tetracycline-loaded chitosan hydrogel showed good antibacterial effect even under alkaline environment, which displayed better stability compared with free tetracycline. Moreover, the tetracycline-loaded chitosan hydrogel exhibited lower cytotoxicity than did tetracycline alone, suggesting that this tetracycline-loaded chitosan hydrogel could be a more useful dosage form than separate doses of tetracycline. The novel aspects of this study include the cytotoxicity study and the in vitro and in vivo assays, which might be useful for other researchers in this field.

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Graphical abstract To realize the controlled release property, lower cytotoxicity, and long-term bioactivity of tetracycline, genipin cross-linked chitosan hydrogel was used as the carrier of tetracycline. The hydrogel could controllably release tetracycline with bioactivity. The hydrogel showed good antibacterial effect even under alkaline environment. The hydrogel exhibited lower cytotoxicity than did tetracycline alone.

     

温度对WC-WB-CoCr涂层高温摩擦磨损性能的影响

采用超音速火焰喷涂(HVOF)制备了WC-WB-CoCr涂层,研究了温度对WC-WB-CoCr涂层高温摩擦磨损性能的影响。通过SEM、XRD和显微硬度仪对涂层的微观组织、相结构和力学性能进行表征。通过摩擦磨损试验机和拉曼光谱仪研究了WC-WB-CoCr涂层的高温摩擦学性能和氧化产物,采用台阶仪扫描磨痕形貌并计算WC-WB-CoCr涂层的磨损率。结果表明：WC-WB-Co-Cr涂层主要由WC和CoW₂B₂组成,涂层结构致密,与基体结合紧密;随着磨损试验温度升高,涂层的摩擦系数从0.66降低到0.57,涂层的磨损率随着温度的升高而升高,但是其磨损率增长程度随着温度的升高而降低。在高温磨损过程中,磨痕表面的氧化膜主要由WO₃和CoWO₄组成,且CoWO₄比WO₃表现出更好的耐高温磨损性能。涂层的主要磨损机制为氧化磨损、疲劳磨损和粘着磨损。     

熔盐电解法制备单一Sm2Fe17合金相的机理研究

选择在LiF-CaF₂-SmF₃熔盐体系中,采用熔盐电解法在1160℃下通过恒电流在Fe阴极表面获得了不同厚度(17.22～40.34μm)的Sm₂Fe₁₇合金层,同时通过循环伏安法与方波伏安法研究了Sm³⁺在W与Fe阴极上的电化学行为。结果表明,Sm³⁺无法单独沉积于W电极上,Sm³⁺在铁阴极上的还原为Sm⁰分为2步,首先在-0.33V(vs.Cr/Cr₂O₃)发生Sm³⁺还原为Sm²⁺的可溶-可溶型反应,然后当电极电势超过-0.78V(vs.Cr/Cr₂O₃)时Sm²⁺开始在阴极界面处上发生欠电势还原,在Fe电极表面生成Sm₂Fe₁₇合金,这是由于在Sm₂Fe₁₇合金中降...     

A graph deep learning method for short‐term traffic forecasting on large road networks

Short‐term traffic flow prediction on a large‐scale road network is challenging due to the complex spatial–temporal dependencies, the directed network topology, and the high computational cost. To address the challenges, this article develops a graph deep learning framework to predict large‐scale network traffic flow with high accuracy and efficiency. Specifically, we model the dynamics of the traffic flow on a road network as an irreducible and aperiodic Markov chain on a directed graph. Based on the representation, a novel spatial–temporal graph inception residual network (STGI‐ResNet) is developed for network‐based traffic prediction. This model integrates multiple spatial–temporal graph convolution (STGC) operators, residual learning, and the inception structure. The proposed STGC operators can adaptively extract spatial–temporal features from multiple traffic periodicities while preserving the topology information of the road network. The proposed STGI‐ResNet inherits the advantages of residual learning and inception structure to improve prediction accuracy, accelerate the model training process, and reduce difficult parameter tuning efforts. The computational complexity is linearly related to the number of road links, which enables citywide short‐term traffic prediction. Experiments using a car‐hailing traffic data set at 10‐, 30‐, and 60‐min intervals for a large road network in a Chinese city shows that the proposed model outperformed various state‐of‐the‐art baselines for short‐term network traffic flow prediction.     

Seismic performance of corrugated steel plate concrete composite shear walls

In this paper, composite shear walls with different encased steel plates (flat, horizontal corrugated, and vertical corrugated) were tested and simulated by Abaqus to investigate the seismic behavior of corrugated steel plate concrete composite shear walls (SPCSWs). The failure characteristics, deformation and energy dissipation capacity, and stiffness and bearing capacity of the structures under low‐frequency cyclic load were analyzed, and indexes of the seismic performance were obtained. The formulas of the shear‐bearing capacity of steel plate concrete composite shear walls are suggested, and the shear‐sharing ratio of each member is obtained. According to the obtained results, corrugated steel plates can bond with concrete well, and the bearing capacity of the vertical corrugated SPCSW are higher than that of the horizontal corrugated SPCSW. Compared with flat SPCSW, corrugated SPCSW has higher initial stiffness and lateral stiffness, better ductility and energy dissipation ability, and the degradation of bearing capacity and stiffness is slower. The shear‐sharing ratio of a steel plate is larger than that of reinforced concrete in the flat SPCSW and the vertical corrugated SPCSW, the shear force shared by steel plate and reinforced concrete in horizontal corrugated SPCSW is basically the same.     

电力电缆隧道结构病害及检测评估方法探讨

电力电缆隧道是目前常见的城市地下空间利用形态之一,但是该类隧道的结构病害检测技术体系和规范尚不完善,影响了该类隧道的病害评定及相应处治。电力电缆隧道的病害类型主要包括隧道渗漏水、隧道衬砌裂损、衬砌结构腐蚀这三大类型,其中影响较大的为隧道渗漏水。在电力电缆隧道的检测工作中,需要结合电力隧道的工作环境条件、功能特点,明确检测的目的和需求,有针对性地调查和收集相关的信息和资料以制定检测方案。检测的内容可以划分为外观检查、结构安全性检查、结构耐久性检查这三大类内容,以便选取适宜的仪器和方法开展电力隧道检测工作。论文提出了确定电力隧道结构区段的分项评定标准及综合技术状况评定方法,并建议依据检测评定结果对电力隧道采取对应的养护措施。