Preparation and properties of poly(siloxane‐ether‐urethane)‐acrylic hybrid emulsions

Poly(siloxane‐ether‐urethane)‐acrylic (PU‐AC) hybrid emulsions were prepared by introducing different hydroxyethoxypropyl‐terminated polydimethylsiloxane (PDMS) content into the acrylic‐terminated poly(ether‐urethane) backbone and then in situ copolymerizing with methyl methacrylate and butyl acrylate via emulsion process. The effects of PDMS on the particle size and viscoelastic behavior of the hybrid emulsions were investigated. Meanwhile, the hydrogen bonding, mechanical and thermal mechanical properties, water resistance, the surface gloss, and wettability of the resultant hybrid films were also studied. The results showed that all the hybrid emulsions showed shear‐thinning behaviors, and the introduction of PDMS resulted in the formation of the hybrid emulsions with increased average particle size and decreased viscosity. The chemical bonds built between PU and AC yielded higher than 73% crosslinking fraction in all the hybrid materials, but this value decreased with increasing PDMS content because PDMS reduced the hydrogen bonding interactions and enhanced the phase separation. As a result, an increase in the PDMS content led to an increase in the elongation, water resistance, surface roughness, and water hydrophobic of the films, but the tensile strength, hardness, storage modulus, and glass transitions temperature decreased. It is suggested that introduction of PDMS can provide the hybrid materials with the improved flexibility, water resistance, and surface hydrophobicity, which has potential application value in the fouling‐release coatings, biomaterials, and surface fishing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44927.     

中药肾脏毒性与四气、五味及归经相关性研究

研究中药肾脏毒性与四气、五味及归经的关系。以专著和文献中报道的肾脏毒性中药及一般中药为研究对象,以《中药大辞典》记载的药性理论为主要依据,用χ~2检验统计分析肾脏毒性中药的四气、五味及归经分布规律,并分析其相关性。结果显示肾脏毒性中药四气顺序依次为:温性、寒性热、凉、平性,一般中药四气顺序依次为:热性、凉性温性、寒性平性。肾脏毒性中药五味分布规律顺序依次为:苦味、辛味甘味酸味、咸味,一般中药五味分布规律顺序依次为:苦味、甘味辛味酸、咸味。肾脏毒性中药归经顺序依次为:肝经肺、肾、大肠、心、脾、胃经三焦、膀胱、胆、小肠、心包经,一般中药归经顺序依次为:肝经肺、肾、心、脾、胃经大肠经膀胱经胆、小肠、三焦、心包经。结果表明肾脏毒性中药及一般中药在四气、五味及归经方面都有明显的差别。肾脏毒性中药与一般中药之间的四气、五味及归经分布也存在明显的差别。     

氟硅酸中氟、氯、硫酸根、磷酸根的测定

采用离子色谱法同时测定氟硅酸中硫酸根、磷酸根、氯离子、游离氟的检测方法。对氟硅酸的前处理方法和仪器条件进行了优化,以氢氧化钾溶液进行淋洗,阴离子分析柱(Ion Pac AG11-HC,250 mm×4 mm)分离,采用电导检测器定量。结果表明,氟离子、氯离子、硫酸根、磷酸根的检测限分别为0.001、0.05、0.01、0.01 mg/L。各离子的回收率为96%~99%,相对标准偏差为1.5%~3.8%。对实际样品进行检测,满足工业氟硅酸检测多离子的要求。     

Fault-Tolerant Control for Markovian Jump Delay Systems with an Adaptive Observer Approach

This paper investigates the problem of fault estimation and fault-tolerant control for a class of Markovian jump systems with mode-dependent interval time-varying delay and Lipschitz nonlinearities. In this paper, a new adaptive fault observer is designed to solve the problem of fault estimation. The proposed observer can estimate the states and faults simultaneously, whether faults are of time-varying or constant characterization. Based on the fault estimation, a fault-tolerant controller is designed to stabilize the closed-loop system. Sufficient conditions for the existence of the observer gain and fault-tolerant controller gain are got by a set of linear matrix inequalities. Finally, a numerical example is presented to illustrate the effectiveness of the proposed fault-tolerant control method.     

基于逻辑Petri网模型的断路器数字孪生车间系统

针对断路器批量化制造过程中的生产逻辑关系建模与控制问题,提出一种基于逻辑Petri网的断路器数字孪生车间系统建模与控制方法.基于物理车间的构成信息和断路器批量化制造工艺特点,建立了逻辑约束的递进式Petri网,实现了对物理生产过程的精准建模分析.在此基础上,采用模型结构分析、系统协同优化、物理引擎开发等方法,结合逻辑P...     

镍-磷-纳米碳化硅-聚四氟乙烯化学复合镀对纺纱钢丝圈寿命的影响

为研究分析不同表面处理工艺对钢丝圈纺纱性能的影响,进一步提高钢丝圈使用寿命,采用化学镀的方法向镀液中添加纳米碳化硅(SiC)和聚四氟乙烯(PTFE),制备Ni-P-SiC-PTFE化学复合镀层的钢丝圈。借助扫描电子显微镜、X射线能谱仪和环锭纺纱机等对钢丝圈及镀层的微观结构和性能进行表征。结果表明:相对于Ni-P 化学镀钢丝圈,Ni-P-SiC-PTFE化学复合镀钢丝圈的镀层晶粒细化,厚度均匀,镀层与基体之间结合良好,镀层厚度增加1倍,镀层硬度提高24.5%;采用Ni-P-SiC-PTFE化学复合镀钢丝圈试纺后,纱线的细节、粗节和棉结分别降低40%、18.8%、10.3%,且钢丝圈挂花引起的断头率降低50%,纺纱性能优于Ni-P化学镀钢丝圈;Ni-P-SiC-PTFE化学复合镀钢丝圈上机后的磨损量减少了31.6%,耐磨性得到明显提升。     

社区环境中体育健身设施设计研究

从环境的含义出发,阐述体育健身设施设计对于社区环境建设的重要意义,针对我国目前社区中体育健身设施发展的滞后现状,提出社区中体育健身设施设计的理念、内容、方法等问题,以求促进我国社区环境建设的完善。     

Molecular and Metabolic Mechanism of Low-Intensity Pulsed Ultrasound Improving Muscle Atrophy in Hindlimb Unloading Rats

Low-intensity pulsed ultrasound (LIPUS) has been proved to promote the proliferation of myoblast C2C12. However, whether LIPUS can effectively prevent muscle atrophy has not been clarified, and if so, what is the possible mechanism. The aim of this study is to evaluate the effects of LIPUS on muscle atrophy in hindlimb unloading rats, and explore the mechanisms. The rats were randomly divided into four groups: normal control group (NC), hindlimb unloading group (UL), hindlimb unloading plus 30 mW/cm² LIPUS irradiation group (UL + 30 mW/cm²), hindlimb unloading plus 80 mW/cm² LIPUS irradiation group (UL + 80 mW/cm²). The tails of rats in hindlimb unloading group were suspended for 28 days. The rats in the LIPUS treated group were simultaneously irradiated with LIPUS on gastrocnemius muscle in both lower legs at the sound intensity of 30 mW/cm² or 80 mW/cm² for 20 min/d for 28 days. C2C12 cells were exposed to LIPUS at 30 or 80 mW/cm² for 5 days. The results showed that LIPUS significantly promoted the proliferation and differentiation of myoblast C2C12, and prevented the decrease of cross-sectional area of muscle fiber and gastrocnemius mass in hindlimb unloading rats. LIPUS also significantly down regulated the expression of MSTN and its receptors ActRIIB, and up-regulated the expression of Akt and mTOR in gastrocnemius muscle of hindlimb unloading rats. In addition, three metabolic pathways (phenylalanine, tyrosine and tryptophan biosynthesis; alanine, aspartate and glutamate metabolism; glycine, serine and threonine metabolism) were selected as important metabolic pathways for hindlimb unloading effect. However, LIPUS promoted the stability of alanine, aspartate and glutamate metabolism pathway. These results suggest that the key mechanism of LIPUS in preventing muscle atrophy induced by hindlimb unloading may be related to promoting protein synthesis through MSTN/Akt/mTOR signaling pathway and stabilizing alanine, aspartate and glutamate metabolism.     

大倾角振动给料机衬板磨损机理分析

为大倾角振动给料机的衬板选择了四种材料,即A3钢、中碳低合金钢、2Cr13和高铬铸铁。在自制的低应力磨损试验机上对这四种材料进行了磨损试验,并分析了它们的磨损机理,在低应力磨损工况条件下,合理选择了衬板材料。