Structure of salted-out, solubilized micelles and microemulsions on the perfluorinated anionic surfactant tetraethylammonium perfluorooctyl sulfonate studied by cryogenic transmission electron microscopy

 Tetraethylammonium perfluorooctyl sulfonate (TEAFOS; critical micelle concentration, 1 mM), which forms a threadlike micelle in its pure solution, was adopted to study the structure of salted-out, solubilized micelles and microemulsions by cryogenic transmission electron microscopy. The concentration of the surfactant was kept constant at 60 mM. The micelle solution salted out with LiNO₃ provided a surfactant phase in the presence of a clear interface. The surfactant phase was studded, being formed of homogeneously dispersed spherical micelles, and had no obvious threadlike forms. The micelles, which solubilized the maximum amount of perfluorinated oil, were spherical and had the same size as isolated spherical micelles in pure TEAFOS solution. The microemulsions were formed in the presence of perfluorinated alcohol as cosurfactant and the particles were rotund even when the concentration of the perfluorinated oil was equivalent to that for solubilization and the sizes increased with increasing oil content. The difference in size between the solubilized micelles and microemulsions with the same amount of oil suggested that the oil molecules had been solubilized between palisades of perfluorinated alkyl chains in the micelles and had dissolved in the cores of the microemulsions. Received: 10 September 1999/Accepted: 2 December 1999     

跨温区互联技术

以半导体材料为基础的微电子技术正面临尺寸极限和功耗的双重挑战与发展瓶颈. 低温电子学作为突破上述瓶颈的新兴应用研究学科之一, 得到科研和产业界越来越多的关注.2017 年起, 低温电子学和量子信息处理被国际器件与系统路线图(IRDS) 列为重点关注的十大焦点领域之一. 以低温到室温的微弱、 高频电信号传输为核心的跨温区互联技术是低温电子学和量子信息处理必须解决的关键技术之一. 本文对跨温区互联面临的主要问题与挑战、 目前的进展和未来展望进行了综述, 为我国开展相关研究工作提供参考.     

低温阀门启闭密封试验研究

为了研究低温阀门的启闭密封的特性,对常温和低温下不同密封比压的密封结构进行了启闭密封特性试验,通过试验结果的分析得出了密封比压与泄漏率的关系曲线,并与H.T.洛马宁柯曲线进行了对比,得出了试验工况下密封比压计算修正系数,为低温密封结构设计提供依据。     

ANSYS在低温压力容器应力分析与优化设计中的应用

介绍了大型有限元软件ANSYS在低温压力容器典型应力分析(不连续区局部应力分析、热应力分析、接触应力分析、复合材料应力分析)与优化设计中的应用,论证了ANSYS作为低温压力容器应力分析与优化设计有效手段的实用性和可靠性,为低温压力容器的应力分析和优化设计找到了一条新途径。     

低温吸附、热解吸气相色谱法测定痕量气体硫化氢

采用GC-7890Ⅱ气相色谱仪和自行研制的控温炉,以Chromosorb G为吸附剂。液氮为冷冻剂,低温吸附大气中痕量硫化氢。在130℃下热解吸4min后,直接进入色谱分析。结果表明该方法精密度和回收率均较好。当样品体积为1L时。检出限为0．192ng/L.     

Near-field flow and flame dynamics of LOX/methane shear-coaxial injector under supercritical conditions

The mixing and combustion of liquid oxygen (LOX) and gaseous methane of a shear coaxial injector operating under supercritical pressures have been numerically investigated. The near-field flow and flame dynamics are examined in depth, with emphasis placed on the flame-stabilization mechanisms. The model accommodates the full conservation laws and real-fluid thermodynamics and transport phenomena over the entire range of fluid states of concern. The injector flowfield is characterized by the evolution of the three mixing layers originating from the trailing edges of the two concentric tubes of the injector. As a consequence of the strong inertia of the oxygen stream and light density of methane, a diffusion-dominated flame is anchored in the wake of the LOX post and propagates downstream along the boundary of the oxygen stream. The large-scale vortices shedding from the outer rim of the LOX postengulf methane into the wake recirculation region to react with gasified oxygen. The frequencies of vortex shedding match closely those of the flow over a rear-facing step, mainly due to the large density disparity between LOX and gaseous methane. The effects of the momentum-flux ratio of the two streams are also examined. A higher-momentum methane stream enhances mixing and shortens the potential cores of both the LOX and methane jets.     

工质热物理性质的计算方法及程序设计

文中就工质物性计算程序中常用的公式法和数据库法进行了讨论 ,并着重介绍了公式法的应用原理和编程方法。以低温工质为例 ,介绍了程序计算模块和界面模块各自的特点和相互关系 ,并分别采用 Fortran和 VC+ +两种语言混合编程的方法 ,实现了程序模块间的连接。此方法为DOS和 Windows不同平台间程序的移植提供了借鉴思路     

混合工质在低温制冷中的应用

简单介绍了混合工质的特点,分别就混合工质在节流制冷机、回热式制冷机中的应用做了阐述,总结出混合工质对低温制冷机性能的提高有显著作用,其发展空间广阔.     

Design and evaluation of a new Peltier-cooled laser ablation cell with on-sample temperature control

A new custom-built Peltier-cooled laser ablation cell is described. The proposed cryogenic cell combines a small internal volume (20 cm³) with a unique and reliable on-sample temperature control. The use of a flexible temperature sensor, directly located on the sample surface, ensures a rigorous sample temperature control throughout the entire analysis time and allows instant response to any possible fluctuation. In this way sample integrity and, therefore, reproducibility can be guaranteed during the ablation. The refrigeration of the proposed cryogenic cell combines an internal refrigeration system, controlled by a sensitive thermocouple, with an external refrigeration system. Cooling of the sample is directly carried out by 8 small (1 cm × 1 cm) Peltier elements placed in a circular arrangement in the base of the cell. These Peltier elements are located below a copper plate where the sample is placed. Due to the small size of the cooling electronics and their circular allocation it was possible to maintain a peephole under the sample for illumination allowing a much better visualization of the sample, a factor especially important when working with structurally complex tissue sections. The analytical performance of the cryogenic cell was studied using a glass reference material (SRM NIST 612) at room temperature and at −20 °C. The proposed cell design shows a reasonable signal washout (signal decay within less than 10 s to background level), high sensitivity and good signal stability (in the range 6.6–11.7%). Furthermore, high precision (0.4–2.6%) and accuracy (0.3–3.9%) in the isotope ratio measurements were also observed operating the cell both at room temperature and at −20 °C. Finally, experimental results obtained for the cell application to qualitative elemental imaging of structurally complex tissue samples (e.g. eye sections from a native frozen porcine eye and fresh flower leaves) demonstrate that working in cryogenic conditions is critical in such type of direct sample analysis.