The Influence of Lubricating Agents on the Formation of a Film of a Styrene/Butadiene Latex

The interactions between paper coating lubricants and a carboxylated styrene/butadiene latex emulsion and their effect on latex film morphology have been studied. Calcium stearate, non-ionic polyethylene emulsion and organic triglyceride lubricants showed different interaction characteristics with the latex emulsion according to viscosity, zeta potential and isothermal calorimetric measurements. Calcium stearate lowered the viscosity of the dilute latex emulsion at low concentration suggesting a strong interaction with the latex particles due to a change in the hydrodynamic dimensions of the latex particles. The exothermic enthalpy change supported the assumption of a dissociative interaction. In contrast, both non-ionic polyethylene and organic triglyceride emulsion showed less pronounced enthalpy changes, indicating lower affinity for the latex particles. The reduction in viscosity showed, however, that at low lubricant concentrations there is an interaction between the latex particles and particularly the organic triglyceride emulsion. This suggests a selective adsorption of stabilizing agents and species from the lubricant emulsion which alters the hydrodynamic radius of the latex particles. The effects of the colloidal interactions on the morphology of the latex films monitored by Atomic Force Microscopy (AFM) indicated that specific surface interaction occurring in aqueous media influenced the topography and the surface chemical heterogeneity of the latex films. Especially in the case of calcium stearate, it seems that the dissolved species arrange themselves around the latex particles inhibiting film formation. The organic triglyceride, on the other hand, showed a lower interaction potential in the aqueous phase and it had a different impact on the film formation.     

激光共聚焦扫描显微镜在微机电系统中的应用

在微机电系统中,三维微结构分析是对微加工工艺进行表征的一种重要手段。随着微机电系统研究的深入和产业化的需求,其微结构分析在微机电系统中的重要性日益凸现。激光共聚焦扫描显微镜因其高分辨率、非接触、数据结构分析快等优点,在微结构分析中得到了大量的应用。本文介绍激光共聚焦扫描显微镜的成像原理,重点介绍激光共聚焦显微镜在大角度测量和形貌分析中的应用。同时,与台阶仪、扫描电子显微镜和白光干涉仪相比较,指出激光共聚焦扫描显微镜在微结构分析中的优点和局限性。     

显微观测技术的新进展及其应用

依据显微观测技术的发展过程 ,介绍了普通的光学显微镜和 2 0世纪流行的电子显微镜 ,详细阐述了以扫描隧道显微镜和激光扫描共焦显微镜为代表的新型显微镜系列的发展 ,以及各类显微镜的基本工作原理和应用情况     

Observation particle morphology of colloidal system by conventional SEM with an improved specimen preparation technique

On the basis of our previous report that polymer emulsion with different viscosity can be investigated by conventional scanning electron microscopy (SEM), we have developed an improved specimen preparation technique for obtaining particle morphology and size of colloidal silver, collagen, glutin, and polymer microspheres. In this study, we expect to provide a means for charactering the three-dimensional surface microstructure of colloidal particles. Dilution of the samples with appropriate volatile solvent like ethanol is effective for SEM specimen preparation. At a proper ratio between sample and ethanol, the colloidal particles are dispersed uniformly in ethanol and then deposited evenly on the substrate. Different drying methods are studied to search a proper drying condition, in which the small molecule solvent is removed without destroying the natural particle morphology. And the effects of ethanol in the specimen preparation process are described by analyzing the physicochemical properties of ethanol. The specimen preparation technique is simple and can be achieved in common laboratory for charactering the particle morphology of colloidal system.     

Optic fibre bundle contact imaging probe employing a laser scanning confocal microscope

A small diameter (600 µm) fused optic fibre imaging bundle was used as a probe to compare fluorescent specimens by direct contact imaging using both a conventional fluorescence microscope and a laser scanning confocal microscope (LSCM) system. Green fluorescent polyester fibres placed on a green fluorescent cardboard background were used to model biological tissue. Axial displacement curves support the hypothesis that pinhole size in the LSCM system reduces the contribution of non‐focal plane light. Qualitative comparison showed that the LSCM system produced superior image quality and contrast over the conventional system. The results indicate that the new LSCM–probe combination is an improvement over conventional fluorescence–probe systems. This study shows the feasibility of employing such a small diameter probe in the investigation of biological function in difficult to access areas.     

Preparation mechanism and grinding performance of single-layer self-lubrication brazed CBN abrasive wheels

In order to fabricate single-layer self-lubrication brazed cubic boron nitride (CBN) abrasive wheels, brazing experiments of graphite particles and AISI 1045 steel were carried out using Ag–Cu–Ti filler alloy. Optical microscope, scanning electron microscope, energy-dispersive spectroscopy, and X-ray diffraction were employed to characterize the microstructure and phase constitution of the brazing interface between graphite particles and Ag–Cu–Ti alloy. The formation mechanism was discussed. The results show that TiC resultants are formed via the diffusion behavior of Ti atoms and C atoms towards the joining interface. The chemical resultants of TiC have the granular shape at the early stage. Then, they grow across the joining interface between the graphite particle and Ag–Cu–Ti alloy. Finally, the continuous lamellar TiC compounds come into being around the graphite particle. Chemical joining of graphite particles and Ag–Cu–Ti filler alloy is accordingly realized. A comparative experiment displayed that the single-layer self-lubrication brazed CBN abrasive wheel has better performance than the conventional brazed counterpart.     

Laser scanning confocal microscopy for in situ monitoring of alkali–silica reaction

Alkali–silica reaction (ASR) occurs in concrete between reactive siliceous components in the aggregate and the strongly alkaline pore solution, resulting in the formation of a potentially expansive gel product. Lithium additives have been shown to reduce expansion associated with ASR, but the mechanism(s) by which lithium reduces expansion have not been understood. Therefore, development of an in situ method to observe reactions associated with ASR is highly desirable, as it will allow for non‐destructive observation of the reaction product formation and damage evolution over time, as the reaction progresses. A technique to image into mortar through glass aggregate by laser scanning confocal microscopy (LSCM), producing three‐dimensional representations of the sample was developed. This LSCM technique was utilized to monitor the progress of alkali–silica reaction in mortar samples prepared with alkali‐reactive glass aggregate both in the presence and in the absence of lithium additives: LiNO₃, LiCl or LiOH. The method proved to be effective in qualitatively monitoring crack formation and growth and product formation, within cracks and at the paste/aggregate interface. In particular, dendritic products were observed at the paste/aggregate interface only in those samples containing lithium, suggesting that these products may play a role in ASR mitigation.     

人体皮质骨/纯钛接触副径向微动损伤研究

对新鲜人股骨皮质骨对纯钛球(直径10mm)接触副,在12mm/min加载速度下,分别以最大法向载荷100,200,300,400N进行径向微动实验研究。在动力学特性分析的基础上,用激光共聚焦显微镜和扫描电镜观察皮质骨表面的磨痕形貌。结果显示:随着载荷的增加,股骨皮质骨表现出不同的界面变形行为,损伤随之加重,而且裂纹的产生存在一个临界载荷;裂纹在骨表面主要有4种生长方式,以沿粘合线生长最常见。讨论了减缓骨/种植体界面径向微动损伤的措施,表明降低界面应力和种植体表面改性有利于减缓骨/种植体界面径向微动损伤。     

新型在线监测润滑油黏度和颗粒的复合传感器

为了同时实现对润滑油多信息的状态监测,开发了基于石英晶体微天平(QCM)的能同时监测润滑油黏度和磨损颗粒的复合传感器,并进行了传感器不同油温条件下的稳定性等系列实验。实验结果表明:该型传感器对润滑油黏度和磨损颗粒量的变化具有较高的线性响应和灵敏度,能准确测量润滑油黏度及磨损颗粒含量,且稳定可靠。     

On the development of a confocal Rayleigh-Brillouin microscope

This Note illustrates how a confocal microscope may be modified to conduct Rayleigh-Brillouin mapping experiments that yield very useful information on the mechanical properties of interfacial materials in small volume elements. While the modifications to the microscope are quite straightforward, they do entail significant changes in the optical design. The instrument described herein consists of an argon ion laser equipped with an actively stabilized intercavity etalon that serves as the excitation source for a modified Zeiss LSM 310 confocal laser scan microscope. The optics of the microscope were reconfigured to enable interfacing of the microscope with a tandem triple-pass Fabry-Perot interferometer. This instrument enables three-dimensional Rayleigh-Brillouin spectral mapping of samples at micron spatial resolution. The performance of the instrument and its ability to perform both lateral and depth scans of the acoustic phonon velocity and, hence, the longitudinal modulus across bonded polymer/polymer and polymer/ceramic interfaces are illustrated and discussed.     

Studies of the microstructure of polymer-modified bitumen emulsions using confocal laser scanning microscopy

Polymer-modified bitumen emulsions present a safer and more environmentally friendly binder for enhancing the properties of roads. Cationic bitumen emulsion binders containing polymer latex were investigated using confocal laser scanning microscopy. The latex was incorporated into the bitumen emulsion by using four different addition methods and all emulsions were processed with a conventional colloid mill. The emulsion binder films were studied after evaporation of the emulsion aqueous phase. We show how the microstructure and distribution of the polymer varies within the bitumen binder depending on latex addition method, and that the microstructure of the binder remains intact when exposed to elevated temperature. It was found that a distinctly fine dispersion of polymer results when the polymer is blended into the bitumen before the emulsifying process (a monophase emulsion). In contrast, bi-phase emulsion binders produced by either post-adding the latex to the bitumen emulsion, or by adding the latex into the emulsifier solution phase before processing, or by comilling the latex with the bitumen, water and emulsifier all resulted in a network formation of bitumen particles surrounded by a continuous polymer film. The use of emulsified binders appears to result in a more evenly distributed polymer network compared to the use of hot polymer-modified binders, and they therefore have greater potential for consistent binder cohesion strength, stone retention and therefore improved pavement performance.     

非对称截面螺旋流道中微粒的惯性聚焦效应

为实现生物微粒/细胞的精确操控,提出了一种非对称截面螺旋流道结构的惯性微流控芯片.基于仿真和实验的方法,对不同尺寸微粒在微流道中的惯性聚焦行为进行了研究.设计了一种"L"形截面的螺旋流道,采用仿真软件COMSOL研究微流道中的二次流场及微粒的运动轨迹.使用UV激光切割与等离子清洗键合的工艺制作芯片样件,采用高速摄像机和...     

Effective viscosity measurement of interfacial bubble and particle layers at high volume fraction

An experimental method for measuring the effective viscosity of two dimensional dispersion systems is proposed. The method is based on interfacial rheology, which was originally developed to investigate surface active adsorption layers such as protein film formed at liquid–liquid interfaces. Bubbles or rigid particles at around 50% of volume fraction in liquid are positioned in the gap between a rotating disk and a stationary cylindrical container. With this configuration, shear-rate dependent effective viscosities of bubble and particle layers were investigated. Steep shear-thinning property is observed for spherical bubble systems in the shear rate regime from 10⁻¹ to 10² s⁻¹. This is explained by topological transition from regular to random arrangement of the bubbles at the interface. For rigid particle systems, the viscosity starts from high value due to solid contact friction, then decreases sharply due to fluidization process until inter-particle collision lead to an increase of the viscosity.     

浅谈激光共聚焦显微镜使用技巧

本文简要介绍了激光扫描共聚焦（LSCM）成像原理,并以花粉为例,详细介绍了共聚焦针孔直径、光电倍增管检测器增益、激光强度、扫描速度、扫描方式、Z轴步距等重要参数设置对共聚焦成像的不同影响。探讨了正确使用LSCM的方法与技巧,如获取高质量的图像、图像保存及图像处理,以便为科技人员利用LSCM开展更多植物学与环境科学相关的研究提供参考。     

High‐temperature laser‐scanning confocal microscopy as a tool to study the interface instability during unsteady‐state solidification of low‐carbon steel

Solidification microstructure is a defining link between production techniques and the mechanical properties of metals and in particular steel. Due to the difficulty of conducting solidification studies at high temperature, knowledge of the development of solidification microstructure in steel is scarce. In this study, a laser‐scanning confocal microscopy (LSCM) has been used to observe in situ and in real‐time the planar to cellular to dendritic transition of the progressing solid/liquid interface in low carbon steel. Because the in situ observations in the laser‐scanning confocal microscopy are restricted to the surface, the effect of sample thickness on surface observations was determined. Moreover, the effect of cooling rate and alloy composition on the planar to cellular interface transition was investigated. In the low‐alloyed, low‐carbon steel studied, the cooling rate does not seem to have an effect on the spacing of the cellular microstructure. However, in the presence of copper and manganese, the cell spacing decreased at higher cooling rates. Higher concentrations of copper in steel resulted on an increased cell spacing at the same cooling rates.     

浅谈共聚焦显微技术

共聚焦显微镜以其高对比度、高分辨率及可重建三维图像的独特优势,在生物医学研究、微细加工、半导体和高分子材料的生产检测等领域获得广泛应用。常用的共聚焦技术方法有:传统的激光扫描共聚焦显微镜(LSCM),其特点是获得的图像对比度和分辨率高,但需要逐点扫描,帧成像时间长,系统复杂,体积大,价格昂贵;碟片共聚焦显微镜(SDCM)是采用多光束扫描的方法来获得共聚焦图像,速度可以大大提高,但牺牲了共聚焦图像的分辨率,系统更为复杂,且不能调整轴向分辨率;结构光显微镜(SIM)具有方法简单,可模块化设计,成本低,成像质量接近于激光扫描共聚焦显微镜,成像速度快,性价比较高。     

A highly reliable and budget-friendly Peltier-cooled camera for biological fluorescence imaging microscopy

The SAC8.5, a low-cost Peltier-cooled black and white 8-bit CCD camera for astronomy, was evaluated for its use in imaging microscopy. Two camera–microscope configurations were used: an epifluorescence microscope (Nikon Eclipse TE2000-U) and a bottom port laser scanning confocal microscope system (Zeiss LSCM 510 META). Main advantages of the CCD camera over the currently used photomultiplier detection in the scanning setup are fast image capturing, stable background, an improved signal-to-noise ratio and good linearity. Based on DAPI-labelled Chinese Hamster Ovarian cells, the signal-to-noise ratio was estimated to be 4 times higher with respect to the currently used confocal photomultiplier detector. A linear relationship between the fluorescence signal and the FITC-inulin concentrations ranging from 0.05 to 1.8 mg mL⁻¹ could be established. With the SAC8.5 CCD camera and using DAPI, calcein-AM and propidium iodide we could also distinguish between viable, apoptotic and necrotic cells: exposure to CdCl₂ caused necrosis in A6 cells. Additional examples include the observation of wire-like mitochondrial networks in Mito Tracker Green-loaded Madin–Darby canine kidney cells. Furthermore, it is straightforward to interface the SAC8.5 with automated shutters to prevent rapid fluorophore photobleaching via easy to use astrovideo software. In this study, we demonstrate that the SAC8.5 black and white CCD camera is an easy-to-implement and cost-conscious addition to quantitative fluorescence microfluorimetry on living tissues and is suitable for teaching laboratories.     

石蜡基和环烷基基础油复配乳化切削液性能研究

以不同黏度石蜡基和环烷基复配基础油调和一系列乳化液,分别通过电导率法、马尔文颗粒度法考察乳化液的稳定性,采用Micro Tap G-8攻丝扭矩试验考察乳化液的切削加工性能。研究结果表明,采用石蜡基和环烷基复配的黏度为20 mm2/s基础油所制备的乳化液的稳定性最佳,且有色金属切削加工性能突出。     

PHOEBE,a prototype scanning laser-feedback microscope for imaging biological cells in aqueous media

Based on the principle of laser-feedback interferometry (LFI), a laser-feedback microscope (LFM) has been constructed capable of providing an axial (z) resolution of a target surface topography of ～ 1 nm and a lateral (x, y) resolution of ～ 200 nm when used with a high-numerical-aperture oil-immersion microscope objective. LFI is a form of interferometry in which a laser's intensity is modulated by light re-entering the illuminating laser. Interfering with the light circulating in the laser resonant cavity, this back-reflected light gives information about an object's position and reflectivity. Using a 1-mW He–Ne (λ = 632·8 nm) laser, this microscope (PHOEBE) is capable of obtaining 256 × 256-pixel images over fields from (10 μm × 10 μm) to (120 μm × 120 μm) in ～ 30 s. An electromechanical feedback circuit holds the optical pathlength between the laser output mirror and a point on the scanned object constant; this allows two types of images (surface topography and surface reflectivity) to be obtained simultaneously. For biological cells, imaging can be accomplished using back-reflected light originating from small refractive-index changes (> 0·02) at cell membrane/water interfaces; alternatively, the optical pathlength through the cell interior can be measured point-by-point by growing or placing a cell suspension on a higher-reflecting substrate (glass or a silicon wafer). Advantages of the laser-feedback microscope in comparison to other confocal optical microscopes include: the simplicity of the single-axis interferometric design; the confocal property of the laser-feedback microscope (a virtual pinhole), which is achieved by the requirement that only light that re-enters the laser meeting the stringent frequency, spatial (TEM₀₀), and coherence requirements of the laser cavity resonator mode modulate the laser intensity; and the improved axial resolution, which is based on interferometric measurement of optical amplitude and phase rather than by use of a pinhole as in other types of confocal microscopes.     

An optical-axis freezing stage for laser-scanning microscopy of broad ice–water interfaces

This article presents a method to view a dynamic ice interface along the axis of ice growth using a laser‐scanning microscope. A deep liquid volume is chilled from below so that ice growth is directed upward toward the microscope objective. The interface is made visible by rejection of fluorescent dye from the solid phase into the liquid. Images of the interface morphology in water with solutes of interest to cryobiology illustrate the imaging capability. These images are processed to quantify the lamellar structure of the ice interface. The optical‐axis cryostage provides advantages over horizontal arrangements because (1) immersion objectives enhance, rather than disturb, the desired thermal gradient, and (2) features in the ice interface are not confined within a narrow capillary tube or microscope slide. This arrangement loses some of the thermal control found in planar freezing stages, and the dynamic, refractive interface presents challenges to confocal microscopy.