静电纺丝法制备ZnO构建酪氨酸酶生物传感器检测邻苯二酚

电化学生物传感器在环境监测、生物与食品分析等领域应用广泛。本文采用静电纺丝法制备了氧化锌微纳米纤维材料,并负载酪氨酸酶（Tyr）构建了检测邻苯二酚的生物传感电极。利用X射线粉末衍射（XRD）、扫描电子显微镜（SEM）表征了氧化锌微纳米纤维的形貌结构,采用循环伏安法（CV）和计时电流法（IT）优化了检测邻苯二酚的工作条件。结果表明,制备的Tyr/ZnO/CS/GCE生物传感电极具有良好的电化学性能,在反应过程中为扩散控制,对邻苯二酚的检测在5～50μmol/L的浓度范围内具有较好的线性关系,最低检测限为1.9041μmol/L,灵敏度为376.31μA/(mmol·L·cm²),氧化锌的加入可增强酪氨酸酶的稳定性,在尿素、多巴胺和葡萄糖3种电化学活性相近物质存在的情况下仍对邻苯二酚的检测有较好的选择性,且具有良好的循环稳定性。     

Viscosity of glass-forming melt at the bottom of high-level waste melter-feed cold caps: Effects of temperature and incorporation of solid components

During the final stages of conversion of melter feed (glass batch) to molten glass, the glass-forming melt becomes a continuous liquid phase that encapsulates dissolving solid particles and gas bubbles that produce primary foam at the bottom of the cold cap (the reacting melter feed in an electric glass-melting furnace). The glass-forming melt viscosity plays a dominant role in primary foam formation, stability, and eventual collapse, thus affecting the rate of melting (the glass production rate per cold-cap area). We have traced the glass-forming melt viscosity during the final stages of feed-to-glass conversion as it changes in response to changing temperature and composition (resulting from dissolving solid particles). For this study, we used high-level waste melter feeds—taking advantage of the large amount of data available to us—and a variety of experimental techniques (feed expansion test, evolved gas analysis, thermogravimetric analyzer-differential scanning calorimetry, X-ray diffraction, and viscometer). Starting with a relatively low value at the moment when the melt connects, melt viscosity reached maximum within the primary foam layer and then decreased to its final melter operating temperature value. At the cold-cap bottom—the boundary between the primary foam layer and the thermal boundary layer—where physicochemical reactions of a melter feed influence the driving force of the heat transfer from the melt to the cold cap, the melt viscosity affects the rate of melting predominantly through its effect on the temperature at which primary foam is collapsing.     

Effect of hybrid polysphosphazene coating treatment on carbon fibers on the interfacial properties of CF/PA6 composites

Carbon fiber (CF) reinforced polyamide 6 (PA6) composite has an extensive application. However, the performances of CF/PA6 composite are constrained by the poor interfacial adhesion between CF and PA6 matrix. In this article, in order to strengthen the interfacial adhesion of CF/PA6 composite, a layer of poly(cyclotriphosphazene-co-4,4′-sulfonyldiphonel) (PZS) hybrid coating with plenty of PZS microspheres (PZSMS) was successfully introduced onto CF surface through facile in situ polymerization. After surface modification, the surface morphologies and the surface chemical structures of fibers changed distinctly. On one hand, the PZSMS provided more contact points and increased mechanical interlocking between CF and PA6 matrix. On the other hand, numerous hydrogen bonds between CF and PA6 were formed due to a great amount of unique polar groups on modified CF surface. Consequently, in comparison with untreated CF, the interfacial shear strength of CF-PZSMS/PA6 composites was improved from 37.68 ± 3.16 to 53.79 ± 3.38 MPa, by 42.75 ± 3.02%. The results indicated that PZS hybrid coating on fiber surface effectively improved the interfacial adhesion of CF/PA6 composites, and the stronger hydrogen bonding and the enhanced mechanical interlocking synergistically played a major role in such significant improvements.     

无机絮凝剂处理含三种重金属选矿废水实验研究

通常选矿废水中含有Cu、Pb、Zn等重金属离子,目前多采用絮凝沉淀法进行处理,但不同实验条件下不同絮凝剂的去除效果差异较大。本文以含三种重金属离子的模拟选矿废水为研究对象,以溶液p H和絮凝剂种类作为控制变量进行研究,结果表明:当溶液酸碱度大于等于最适p H时,大部分重金属离子以氢氧化物沉淀的形式出现;当溶液酸碱度小于最适p H时,絮凝剂的种类能直接影响不同重金属离子的沉淀效果。     

Brief Review of Precipitated Iron-Based Catalysts for Low-Temperature Fischer–Tropsch Synthesis

Topics in Catalysis - Fischer–Tropsch synthesis (FTS) is a promising way to produce clean liquid fuels and high value-added chemicals from low-value carbon-containing resources such as coal,...     

Effect of coupling agent content on properties of composites made from polylactic acid and chrysanthemum waste

Chrysanthemum flower is among one of the highly sought after and widely planted flower crops, in particular for cultural and religious ceremonies. However, the chrysanthemum stem and stalk have little value and usually discard as by‐product waste from floristry. The objective of this research is to investigate the potential value of utilizing chrysanthemum stem and stalk as reinforcing fillers for thermoplastic composites. In this study, 2‐mm thick composite sheet containing predefined formulations of polylactic acid (PLA), chrysanthemum waste filler (CWF) ranging from 15 to 60 phr, and maleated polyethylene (MAPE) coupling agent up to 5 phr were prepared with the aid of Haake internal mixer and compression molding. The effect of MAPE loading on tensile, thermal, and morphological properties of PLA/CWF composites was investigated. The findings revealed that PLA/CWF composite attained improved tensile modulus compared to the neat PLA, and the tensile modulus increases with higher concentration of CWF. However, both tensile strength and elongation at break reduces with increase loading of CWF. Overall, PLA/CWF composites with MAPE shows better performance compared to those without MAPE, where an optimum strength of 21.8 MPa can be achieved with 60 phr CW and 3 phr MAPE. The measured tensile strength is comparable to alternatives natural fiber thermoplastic composites demonstrating its potential to be used in non‐structurally demanding application. J. VINYL ADDIT. TECHNOL., 26:10–16, 2020. © 2019 Society of Plastics Engineers     

中美煤矿事故调查报告的对比研究

为找出中美煤矿事故调查报告的异同,给我国事故调查报告的编写提供具体建议,以中美两国正式发布的事故调查报告为研究基础,系统调研事故调查相关文献,对事故调查报告编写依据进行分析,并以中国金山沟煤矿"10·30"特别重大瓦斯爆炸事故和美国Upper Big Branch煤矿事故调查报告为例,从报告的结构内容和原因2方面进行具体分析。结果表明,中国应该出台统一的煤矿事故调查报告编写标准,实现事故调查报告标准化;美国事故调查报告不包含责任追究部分,原因分析部分所占篇幅多;美国事故调查进行原因分析时与中国所站角度不同,美国仅对事故单位进行分析,中国除此外还分析相关单位问题。     

市政道路工程与排水工程相互影响的设计及其体会

阐述市政道路工程与排水工程设计的有关内容,以工程实例介绍相互间的影响,结合自身工程设计实践提出几点经验体会。     

石墨烯增强铝基复合材料导电性能的研究

采用粉末冶金法,制备了石墨烯增强铝基复合材料,研究了石墨烯含量及烧结温度对复合材料组织及力学性能、导电性能的影响.结果表明,当石墨烯添加量为0.3％(质量分数)、在580 ℃烧结1h时,所得复合材料晶粒较细小,分布较均匀,致密度最大,为90.14％,电导率最高,为25.54 MS/m,硬度最大,为HB23.35.     

彩涂板涂层厚度测定方法研究

分析了GB/T13448—2006标准中介绍的4种彩涂板涂层厚度测定方法的优劣及影响测定结果的因素,并对目前国际、国内可采用的测定涂层厚度的检验方法进行了调查研究。提出了在彩涂板目前产品水平下最合适的涂层厚度测定方法。