单分子毛细管电泳

对室温下液流中的单分子光学检测技术的基本原理、主要方法以及它在生物学中的应用做了综述。重点强调了毛细管电泳与单分子检测相结合-单分子毛细管电泳在分析科学中战略上的重要性，并展望了单分子光学检测技术为特征的单分子毛细管电泳在分析化学中的应用前景。     

石墨烯基单原子催化剂的合成、表征及分析

单原子催化剂具有配位数低、配位环境特殊、原子利用率极高和催化位点高度均一等优点,是沟通均相和异相催化剂之间的桥梁,有助于更好地认识催化反应的本质。本文综述了近年来国内外石墨烯基单原子催化剂的多种合成方法,包括原子层沉积法、浸渍-煅烧法、缺陷捕获法、配位锚定法和其他新颖方法的制备过程、合成原理和表征。在此基础上,本文对石墨烯基金属单原子催化剂在催化方面的性能进行阐述和分析,以期为单原子催化剂制备提供指导和参考。     

单分子荧光成像研究单颗粒纳米催化机制

纳米颗粒通常具有优异的催化性能,但由于其内在的异质性,宏观水平的表征难以确定单个纳米颗粒可靠的构效关系和潜在的催化反应机制.单分子荧光成像技术具有单分子灵敏度、高时空分辨率的优点,可以在单颗粒水平实现反应产物的超灵敏检测,因而在纳米催化领域得到了广泛应用.本文综述了单分子荧光成像的发展以及该技术在揭示单颗粒纳米催化反应机制中的应用,主要包括尺寸效应、晶面效应、表面缺陷、等离激元效应、双金属效应、活化能、纳米限域效应以及单颗粒催化通讯等方面.最后总结和展望了单分子荧光成像技术在纳米催化研究中的挑战与发展方向.     

单铌和单过氧铌杂多配合物的合成、表征及催化性能

过氧铌钨磷杂多酸盐;催化活性;单铌和单过氧铌杂多配合物的合成、表征及催化性能     

Aerolysin单分子界面的构建及高选择性单分子检测

提出了一种基于Aerolysin膜蛋白质分子构建单分子界面的方法, 运用蛋白质工程技术对单分子界面进行定点修饰, 所建立方法灵活、 可控且重复性好. 采用Poly(dA)₄为探针分子对修饰后的单分子界面进行了表征, 结果表明, 在孔口处的Arginine修饰影响了寡聚核苷酸的选择性. 为进一步理解Aerolysin单分子界面及合理设计功能性单分子界面提供了参考.     

单原子催化——概念、方法与应用

单原子催化体系的成功构建将催化领域研究深入到更小的尺度范围,不仅可以从原子层次认识复杂的多相催化反应,而且由于其优越的催化性能在工业催化中具有巨大的应用潜能。本文基于近年来国内外研究者在单原子催化领域的研究工作,总结归纳了单原子催化剂的性能特征,介绍了单原子催化剂的制备手段、表征技术、理论研究及其在CO氧化、选择性加氢和光电催化等反应中的应用研究进展,分析了单原子催化剂特殊的电子结构对催化性能和反应机理的影响及其作用机制,指出了单原子催化体系在研究领域取得的突破与不足,对于深刻认识单原子催化的概念与原理、完善实验与理论研究方法、拓展应用范围和尽早实现工业应用提出了建议与展望。     

开链单烯和开链单炔的同卤代物的异构体计数

将Polya计数定理用于求开链单烯和开链单炔被同种卤素取代的取代物的各种异构体计数母函数,同时讨论了被同种卤素取代的单环烯烃同系物和由4种卤素取代的单烯和单炔的各种异构体计数母函数的求法。     

单分子宽场光学显微成像技术

单分子宽场光学显微成像技术是单分子检测技术的一种,具有通量高、参数多样、可实时动态监测等优点。本文评述了单分子宽场光学显微成像的技术方法、标记探针、判定原则、检测参数及其在分析化学、生物物理学等领域的应用,指出单分子成像技术正在向仪器设备的实用化、简易化,测量参数的精确化、可视化,研究范围的广泛化、复杂化等方面发展。未来几年单分子成像的研究重点可能会集中在实用定量、突破衍射极限的距离测量、重要生物过程的机理探索和纳米目标物的表征等方面。     

白血病细胞内磷酸单酯的31P核磁共振分析

对人早幼粒白血病细胞HL－60和人淋巴瘤白血病细胞Molt-4的^31P NMR谱进行了分析，HL－60和Molt-4细胞显示很强的磷酸单酯峰，磷酸单酯峰中包含有磷酸胆碱和磷酸乙醇胺；并进一步对磷酸单酯峰的特征及形成进行了分析；结果提示可能根据磷酸单酯峰的特征对癌进行诊断和分析。     

氢醌单丙酸酯的改进合成

氢醌单丙酸酯的改进合成马美玲（西安地质学院应用化学系，西安７１００５４）邓月松谢明贵（四川大学化学系，成都６１００６４）关键词除色素剂氢醌单羧酸酯氢醌单丙酸酯中图分类号Ｏ６２５．３２３氢醌单脂肪酸酯是一类很好的皮肤去色素剂，其中尤以氢醌单丙酸酯为最佳...     

蛋白质的单分子包埋

单分子包埋是一种高效的蛋白质包埋新方法.蛋白质的单分子包埋是利用蛋白质上的某些基团可以与修饰剂反应的特点,将蛋白质先与修饰剂反应,再进行单个蛋白质分子的包埋.该方法获得的蛋白质单分子包埋颗粒粒径处于纳米尺寸范围,外壳的材料层薄至几到几十纳米.本文介绍了蛋白质的单分子包埋的原理及目前蛋白质单分子包埋的主要方法,包括共价结...     

单细胞成像观测研究进展

综述了近几年各种研究手段如STM,AFM和NOSM等在单细胞成像观测方面的研究进展,并对细胞成像观测的历史、现状及发展趋势作了综述。     

Towards high-throughput single cell/clone cultivation and analysis

In order to better understand cellular processes and behavior, a controlled way of studying high numbers of single cells and their clone formation is greatly needed. Numerous ways of ordering single cells into arrays have previously been described, but platforms in which each cell/clone can be addressed to an exact position in the microplate, cultivated for weeks and treated separately in a high-throughput manner have until now been missing. Here, a novel microplate developed for high-throughput single cell/clone cultivation and analysis is presented. Rapid single cell seeding into microwells, using conventional flow cytometry, allows several thousands of single cells to be cultivated, short-term (72 h) or long-term (10-14 days), and analyzed individually. By controlled sorting of individual cells to predefined locations in the microplate, analysis of single cell heterogeneity and clonogenic properties related to drug sensitivity can be accomplished. Additionally, the platform requires remarkably low number of cells, a major advantage when screening limited amounts of patient cell samples. By seeding single cells into the microplate it is possible to analyze the cells for over 14 generations, ending up with more than 10 000 cells in each well. Described here is a proof-of-concept on compartmentalization and cultivation of thousands of individual cells enabling heterogeneity analysis of various cells/clones and their response to different drugs.     

Accuracy of single measurements

Single measurements are widely used in industry, trade and science, yet the problem of the estimation of the accuracy of this type of measurements is neither addressed nor even recognized in traditional Metrology. In particular, the Guide to the Expression of Uncertainty in Measurement is devoted to multiple measurements only and does not mention single measurements. This paper studies the problem of estimating the inaccuracy of single measurements and describes solutions to this problem. The proposed methods are based on metrological characteristics of measuring instruments rated in accordance with Recommendation R34 of International Organization of Legal Metrology (OIML). These characteristics are usually given in manufacturer certificates or provided by calibration laboratories. This paper treats single measurements as the basic type of measurement and multiple measurements as sets of successive single measurements. Presented at the 3rd International Conference on Metrology, November 2006, Tel Aviv, Israel. Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher.     

Nanofluidic system for the studies of single DNA molecules

Here, we describe a simple and low-cost lithographic technique to fabricate size-controllable nanopillar arrays inside the microfluidic channels for the studies of single DNA molecules. In this approach, nanosphere lithography has been employed to grow a single layer of well-ordered close-packed colloidal crystals inside the microfluidic channels. The size of the polymeric colloidal nanoparticles could be trimmed by oxygen plasma treatment. These size-trimmed colloidal nanoparticles were then used as the etching mask in a deep etching process. As a result, well-ordered size-controllable nanopillar arrays could be fabricated inside the microfluidic channels. The gap distance between the nanopillars could be tuned between 20 and 80 nm allowing the formation of nanofluidic system where the behavior of a single lambda-phage DNA molecule has been investigated. It was found that the lambda-phage DNA molecule could be fully stretched in the nanofluidic system formed by nanopillars with 50 nm gap distance at a field of 50 V/cm.     

Stochastic collision electrochemistry of single silver nanoparticles

The electrochemical oxidation of single colloidal Ag nanoparticles (NPs) at an electrode surface has previously been studied as an in situ particle-sizing methodology. However, the discovery of multipeak amperometric behavior in 2017 sparked new interest toward understanding the precise physical mechanism of the manner in which a freely diffusing Ag NP interacts with the electrode surface. Random walk simulations, unique electrochemical experiments, and correlated optical/spectroscopic techniques have revealed exciting new results regarding the physical and chemical processes occurring on single NP collision.     

Thermophoresis of single stranded DNA

The manipulation and analysis of biomolecules in native bulk solution is highly desired; however, few methods are available. In thermophoresis, the thermal analog to electrophoresis, molecules are moved along a microscopic temperature gradient. Its theoretical foundation is still under debate, but practical applications for analytics in biology show considerable potential. Here we measured the thermophoresis of highly diluted single stranded DNA using an all‐optical capillary approach. Temperature gradients were created locally by an infrared laser. The thermal depletion of oligonucleotides of between 5 and 50 bases in length were investigated by fluorescence at various salt concentrations. To a good approximation, the previously tested capacitor model describes thermophoresis: the Soret coefficient linearly depends on the Debye length and is proportional to the DNA length to the power of 0.35, dictated by the conformation‐based size scaling of the diffusion coefficient. The results form the basis for quantitative DNA analytics using thermophoresis.     

Probing polymers with single fluorescent molecules

The use of single molecules to study local, nanoscale polymer dynamics is presented. Fluorescence lifetime fluctuations were used to extract the number of polymer segments (N_s) taking part in the rearranging volume around the probe molecule below the glass transition temperature. N_s was dependent on the temperature and it decreased with increasing temperature. Above the glass transition, rotational motion of single molecules was followed in time and typical time-scales of the rotational diffusion were extracted. These two approaches allowed us to obtain non-averaged information about the heterogeneous dynamics present in polymer systems, on the nanoscale, above and below glass transition temperatures.     

Evolution of single nanobubbles through multi-state dynamics

Nanobubble is a rising research field, which attracts more and more attentions due to its potential applications in medical science, catalysis, electrochemistry and etc. To better implement these applications, it is urgent to understand one of the most important mechanisms of nanobubbles, the evolution. However, few attentions have been paid in this aspect because of the methodology difficulties. Here we successfully used dark-field microscopy to study the evolution process of single nanobubbles generated from formic acid dehydrogenation on single Pd-Ag nanoplates. We found some of the nanobubbles in this system can exhibit three distinct states representing different sizes, which can transform among each other. These transitions are not direct but through some intermediate states. Further kinetic analysis reveals complicated mechanisms behind the evolution of single nanobubbles. The results acquired from this study can be applicable to nanobubble systems in general and provide insights into the understanding of mechanisms affecting the stability of nanobubbles and their applications.     

The effects of coil-stretch transition behavior of polyfluorene inks on single droplet formation during inkjet printing

For drop-on-demand (DOD) inkjet printing, stable and single ink droplet formation without satellite dots is the key to improve the print quality. The formation of stable and single droplet is influenced by filament break up and the polymer chain's coil-stretch transition behavior. In this paper, the droplet formation behaviors of polyfluorene (PFO) ink at various driving voltages (V), polymer chain's coil-stretch transition mechanism and its effects on single ink droplet formation are investigated. It indicates that when 58 < V ≤ 63 V, a single and stable droplet is formed with a pulse time of 38.5 μs. At this stage, the Weissenberg number (Wi) < 0.5, the PFO molecular chain is coiled to guarantee stable and single droplets. When V > 63 V, Wi > 0.5, the PFO molecular chain is stretched because of the high hydrodynamic forces, resulting unwanted satellite droplets. When 55 < V ≤ 58 V, the droplet shrinks into the nozzle, which indicates that the kinetic energy supplied by the deformation of the piezoelectric transducer isn't enough to force the droplet to be jetted from the nozzle.