12种脂肪酸的分子连接性指数与其气相色谱保留值的相关关系研究

对月桂酸、豆蔻酸、棕榈酸、油酸、亚油酸、亚麻酸、花生酸、花生烯酸、山嵛酸、芥酸、α-桐酸、蓖麻油酸等12种脂肪酸的气相色谱保留值与其化学结构的关系进行了探讨。计算了这些脂肪酸的部分分子连接性指数。采用多元线性拟合法,求出了各脂肪酸分子中各种碳原子的个数及分子连接性指数与其气相色谱保留关系的回归方程,得到了复相关系数≥0.99,F检验值远高于临界值的回归方程,方程预测的色谱保留值与文献值一致。     

传输线端接复杂电路的电磁耦合时域分析方法

该文基于时域有限差分(FDTD)方法和传输线方程,结合Ngspice软件,提出一种高效的时域混合算法,能够快速模拟空间电磁场作用传输线端接复杂电路的电磁耦合问题.该算法的优势在于实现了空间电磁场辐射与端接复杂电路瞬态响应的协同计算,且避免了对传输线和复杂电路结构的直接建模.首先,将复杂电路通过传输线的特性阻抗进行等效,采用FDTD方法结合传输线方程,求解得到特性阻抗上的入射电流响应.然后,在每个时间步上,将该电流引入复杂电路作为激励源,联合电路模型建立网表文件.最后,使用Ngspice软件读取网表文件,并仿真得到电路各元件上的瞬态响应.通过相应计算实例的数值模拟,与电磁场仿真软件CST的计算结果以及耗用内存和时间进行对比,验证了算法的正确性和高效性.     

透明质酸交联衍生物的研究进展

由于天然透明质酸存在对透明质酸酶及自由基敏感使得在体内保留时间短、力学强度差等缺点,为此很多学者为了提高其抗降解性能和力学强度等展开了对透明质酸的化学改性的诸多研究。文章综述了近年来比较新颖的透明质酸交联技术,包括"点击化学"交联、光交联和自交联技术。同时论述了所获得透明质酸交联凝胶的性质,例如:可原位反应形成凝胶、良好的生物相容性、可生物降解和更便捷的操作性等。同时也展现了透明质酸交联凝胶在软组织填充、组织工程支架、药物载体和再生医学等方面的潜在应用前景。     

我国抗菌剂的应用与发展现状

介绍了抗菌剂的抗菌机理,分析了有机抗菌剂、天然抗菌剂和无机抗菌剂的特点。在不同类型的抗菌剂中,传统的有机抗菌剂占据了主要的市场份额,应用领域也最为广泛;天然抗菌剂的使用安全性最高,资源充足,但提取工艺复杂,生产成本较高;无机抗菌剂是目前研究的热点之一,可基于无机抗菌剂研发新型抗菌涂料、抗菌医疗用品等抗菌产品。在此基础上,综述了各类抗菌剂在工业领域的应用和发展现状,同时展望了未来新型抗菌剂的发展方向。     

铱配合物绿色磷光材料的研究进展

铱配合物作为发光材料,具有发光效率高,磷光寿命短,发光颜色可调等优势,因此被人们广泛研究。作为发光性能最好的一类化合物,绿色磷光铱配合物更加引起人们跟多的重视。文章介绍了近年来绿色磷光铱配合物的研究进展。     

Numerical modeling of particle deposition in ferret airways: A comparison with humans

The ferret is commonly used as an animal model for studying human respiratory diseases, but the validation is lacking. The particle deposition patterns in ferret airways was investigated and compared to those in humans. A computational fluid dynamics method was used to simulate particle deposition in the tracheobronchial airway by using the truncated single-path models. The deposition characteristics of particles with diameters of 1, 3, and 5 μm were investigated under various respiratory rates at different activity conditions (i.e., sedentary, light, moderate, and intense activities). For both human and ferret models, deposition increased with both generation and particle size but decreased with respiratory rate. Particles of 1–5 μm deposit more but transport upper in ferrets than in humans, which suggests that ferrets are more likely to be infected in the proximal airways. The results show that the trend of particle deposition in the ferret airways is similar to that in human airways but with different deposition rates and sites. Our findings indicate that ferret for studying human respiratory diseases is suitable for the upper respiratory diseases, such as human influenza, but may not be suitable for studying the lower respiratory diseases, such as pneumonia.

Copyright © 2017 American Association for Aerosol Research     

Process monitoring in precision cylindrical traverse grinding of slender bar using acoustic emission technology

The precision cylindrical traverse grinding process of slender bar is very complex for the strongly time dependent properties of the wheel. Therefore, it is very difficult for operators to properly judge the grinding state using naked eyes and ears. This calls for automatic monitoring technology that can monitor the process in precision cylindrical traverse grinding to guarantee machining quality and productivity as well as reduction in cost. This study developed an automatic monitoring system for precision cylindrical traverse grinding of slender bar using Acoustic emission (AE) technology. Grinding tests on molybdenum were conducted under traverse conditions in a conventional cylindrical grinder. It was found that larger radial material removal depth results in larger root mean square value of Acoustic emission signals (AE_RMS). Based on this, the AE_RMS was analyzed and used to determine the finishing of spark-out process and the pre-processing of tool alignment. The variation tendency of AE_RMS in one spark-out process was applied to determine when a wheel wears out and has to be dressed. The experimental results showed that the AE system was effective to monitor the pre-processing of tool alignment, spark-out and wheel wear in precision cylindrical traverse grinding of slender bar.

     

滨海地区反稀释法现场试验研究

人工示踪技术可较为准确地估算地下水渗透流速的大小,本文提出在地下水含盐度较高的滨海地区利用淡水作为间接示踪剂进行钻孔内水体置换,通过电导率试验采集电导数据并进行数据分析估算地下水渗透流速的大小,并推导了理想化条件下的地下水渗透流速的计算公式。在工程中进行了原位测试试验,试验结果表明该方法能较好的估算高盐度滨海地区地下水渗透流速的大小。     

土工织物顶压蠕变特性与折减系数研究

常规土工合成材料蠕变特性仅考虑筋材拉伸状态。随着土工合成材料应用愈加广泛,其受力条件也愈加复杂。为研究土工织物在受到顶压力作用下的蠕变特性,研制了顶压蠕变试验装置。采用该装置对Mirafi PET 1300土工织物进行了CBR圆形顶破试验以及40%、50%和60%三种荷载水平下的2400 h圆形顶压蠕变试验,计算了5、10、60和120 a设计年限在不同顶压面积应变下的顶压蠕变折减系数,并与常规拉伸蠕变折减系数对比,建立了顶压蠕变折减系数、设计年限与顶压面积应变三者的量化关系式,以预测顶压蠕变折减系数。结果表明,对于试验土工织物,顶压蠕变折减系数比常规拉伸蠕变折减系数大65.340%～148.496%;随设计年限的增加,顶压蠕变折减系数变化不大;在不同设计年限下,随顶压面积应变的增加,顶压蠕变折减系数保持平稳。为提升工程结构的安全性和耐久性,在土工合成材料受顶压作用情况下,建议设计采用顶压蠕变折减系数。     

围隔导流对太湖蓬坑湾藻类富集效能的影响

针对围隔可改变水体流场、影响藻类漂移聚集,通过改变围隔布设角度和长度,探究不同围隔导流方案下藻类的富集效果。选取梅梁湾内的打捞点蓬坑湾作为研究对象,在建立太湖水量水质模型基础上,进一步建立太湖蓬坑湾套网模型,根据角度、长度两个因素,模拟6种布设方案下藻类富集效果,分析得到最佳角度、长度组合布设方案,并进一步考虑蓬坑湾地形和经济效益,提出适宜于蓬坑湾地形的优化方案。结果表明:围隔布设角度与水流方向呈120°时,湾内富集效果最佳;围隔布设长度越长,蓝藻收集区域越大,湾内富集效果越好;综合考虑地形特点和经济效益,最终确定围隔布设最佳方案为在上下湾口处分别布设一段围隔,布设角度与水流方向呈120°,上下湾口处围隔布设长度分别为100、30 m。研究成果对于改善湖泊水环境具有较好的应用前景。