利用原子力显微镜测量石英岩表面分子沉积膜的粘附力

对原子力显微镜（ＡＦＭ）探针测出的一条到理想的力－位移曲线进行了分析，推导出了根据实测的力－位移曲线计算粘附力的公式。对表面分子沉积膜生长前后的石英岩和扫描探针之间的粘附力进行了实验研究，结果发现这种沉积膜可以降低石英岩表面的粘附力。     

利用原子力显微镜测量石英岩表面分子沉积膜的粘附力

对原子力显微镜（ＡＦＭ）探针测出的一条理想的力位移曲线进行了分析,推导出了根据实测的力位移曲线计算粘附力的公式。对表面分子沉积膜生长前后的石英岩和扫描探针之间的粘附力进行了实验研究,结果发现这种沉积膜可以降低石英岩表面的粘附力     

红枣多糖微结构的原子力显微镜观测

应用原子力显微镜，对红枣多糖的微观形貌进行了观测研究，给出最佳观察方法．发现其单个分子链及其多个侧枝、聚合物链分子间互相缠绕，链间通过糖单元间不同的连接方式衍生出许多聚集体，大小在150-300nm范围内，从而直接证实了多糖大分子具有高度分枝的化学结构．同时发现红枣多糖两股糖链呈螺旋型紧密排列、多个糖链缠绕成股的情况，提示多糖在结构上可能存在类似蛋白质的自组装现象．     

戊二醛对原子力显微镜观测大肠杆菌的影响

戊二醛作为生物材料的固定剂,在原子力显微镜(AFM)制样中已广泛使用.虽然已有用戊二醛观测大肠杆菌的文献报道,但到目前为止,关于戊二醛在AFM观测大肠杆菌中的作用还缺乏系统研究.首先分析AFM扫描图像的假像,进而探讨戊二醛的浓度和固定时间对AFM图像质量和大肠杆菌表面形貌的影响.结果表明,戊二醛的浓度和固定时间对AFM图像的清晰度、大肠杆菌的微观结构以及细胞的三维尺寸都有着重要影响.在相同固定条件下所扫描的AFM图像与扫描电子显微镜(SEM)图像对比发现,两者的形貌相似,而AFM图像比SEM图像分辨率更高,在定量分析上也更有优势.     

戊二醛对原子力显微镜观测大肠杆菌的影晌

戊二醛作为生物材料的固定剂,在原子力显微镜（AFM）制样中已广泛使用．虽然已有用戊二醛观测大肠杆菌的文献报道,但到目前为止,关于戊二醛在AFM观测大肠杆菌中的作用还缺乏系统研究．首先分析AFM扫描图像的假像,进而探讨戊二醛的浓度和固定时间对AFM图像质量和大肠杆菌表面形貌的影响．结果表明,戊二醛的浓度和固定时间对AFM图像的清晰度、大肠杆菌的微观结构以及细胞的三维尺寸都有着重要影响．在相同固定条件下所扫描的AFM图像与扫描电子显微镜（SEM）图像对比发现,两者的形貌相似,而AFM图像比SEM图像分辨率更高,在定量分析上也更有优势．     

煤表面结构介观表象的原子力显微镜(AFM)观测

针对煤复杂的表面结构,运用原子力显微镜(AFM)观测介观尺度下煤表面特征的研究方法,对煤表面形貌进行了初步观测,获得煤样的二维和三维表面形貌图,并进行了煤表面的粒度、粗糙度及功率谱分析.分析结果表明:幅度参数是表征煤样表面粗糙度的特征参数之一;利用功率谱密度有助于分析煤表面的分形特征,将AFM用于煤的表面结构特征研究,为研究煤表面介观特征提供了新的研究方法.     

黄原胶分子形貌的原子力显微镜研究

通过溶胶凝胶的方法制备了黄原胶水溶液,并采用轻敲模式原子力显微镜(AFM)对不同浓度的黄原胶分子溶液的表面微观结构形态进行了观察.实验结果表明,轻敲模式下的AFM能够观测到黄原胶分子的微观结构,浓度为0.1g/L时分子类似于球状体的颗粒,以多聚体形式存在.浓度达到0.01g/L时能够形成稳定的网状结构,当浓度达到0.001g/L的情况下形成单个纤维分子.利用AFM截面软件对网状结构和单个纤维进行分析,发现了云母表面出现的黄原胶分子分别为双链和单链.本文中提出了黄原胶分子从网状结构到单个纤维形成过程的假设模型,很好地解释了实验观察结果,对以后的实验研究有很大意义.     

原子力显微镜实验教学设计

本文结合研究生实验课程教学的特点,就如何将原子力显微镜用于实验教学进行课程内容和教学方案设计进行了阐述,并应用于实验教学,取得了较好的效果,可以为同类实验课程的开设提供有益的参考。     

原子力显微镜针尖在试样表面滑动的力学模型

建立了原子力显微镜针尖在试样表面滑动的力学模型，并通过实验进行了验证。结果表明，粒子间距变大使摩擦力曲线的周期变大，振幅变小；作用势V0反映的是表面自由能的大小，V0增大，摩擦力曲线的振幅变大；阻尼反映的是速度对摩擦力的影响，阻尼变小，摩擦力曲线的振幅基本保持不变，曲线整体下移，但幅度较小。在一定范围内速度对摩擦力的影响不大。     

Atomic force microscopy observation on nuclear reassembly in a cell-free system

Cell-free system is interesting and useful for studying nuclear assembly in mitosis. Atomic force microscopy (AFM), which is a simple way for imaging fixed reassemble nuclei with high resolution, has not been used in the cell-free system. In this paper, we put forward an air-drying sample preparation for AFM. Using AFM, we observed nuclear reassembly process within 100 nm resolution in a cell-free system. As a result, we found that the images were artifact-free, and with higher resolution compared with fluorescent optical microscope images. Furthermore, the morphology of membrane vesicles was obtained dearly, and a dynamic change of morphology during the vesides‘‘ approaching to nuclear envelope was also observed, which is enlightened to understand the mechanism of nuclear envelope assembly.     

Atomic force microscopic observation on substructure of pollen exine in Cedrus deodara and Metasequoia glyptostroboides

The substructure of pollen exine in Cedrus deodara (Roxb.) Loud. and Metasequoia glyptostroboides Hu et Cheng has been examined with an atomic force microscope (AFM). The results indicate that the exine substructure units containing sporopollenin in two species are similar in shape, which are granular, but slightly different in size. In Cedrus the substructure unit of pollen exine appears to be 56-99 nm long and 42-74 nm wide, while in Metasequoia it appears to be 81-118 nm long and 43-98 nm wide. It has been observed that the subunits of pollen exine in Cedrus arranged tightly to form short-rod-like or spheroidal pollen exine units, several or more than ten of which formed an island-like structure. There are various spaces among these island-like structures which are interconnected to occupy the entire pollen exine. In Metasequoia, the subunits of pollen exine also arranged tightly with a distribution tendency of cluster of 3-10, however, no obvious boundary exists among these clusters. From our results, it is concluded that there is no tendency of helical arrangement for the subunits of pollen exine in Cedrus and Metasequoia, and the results support Southworth' view that subunits of pollen exine are granular shape in lattice structure.     

Atomic force microscopic view of the fine topography on the tobacco stigma surface during its response to pollination

During compatible pollination in tobacco, an extracellular matrix （ECM） is secreted from the stigma surface; however, it is unknown whether the pattern of secretion across the stigma depends on the pollen source. In fact, technical limitations have prevented clear observation of ECM secretion. Here, we report the detailed topographic changes on the stigma surface that accompanies intraspecies and interspecies pollination in tobacco using contact mode atomic force microscopy （AFM）. Our results, which show the dynamics and time course of ECM secretion after pollination, indicate that a certain pattern of secretion already exists on the stigma prior to pollination. Intraspecies induced a two-step response, characterized by topographical changes on the stigma surface several hours after pollination, which was distinct from the pattern of ECM secretion induced by interspecies pollination. This difference was confirmed by root-mean-square analysis, which assessed the roughness of the stigma surface. Our findings indicate that compatible pollination not only induces ECM secretion from the stigma, but also results in a specific distribution of the ECM. Thus, this study demonstrates the powerful potential of AFM in studying the pollen-stigma interaction.     

Stretching and imaging studies of single DNA molecules

DNA molecules were stretched on silanized mica surface with the molecular combing technique, and detected with fluorescence microscopy and atomic force microscopy. Meantime, DNA molecules were stretched with a modified dynamic molecular combing technique and studied with atomic force microscopy. The results indicate that, compared with the dynamic molecular combing technique, the modified dynamic molecular combing technique has advantages of less-sample demand and less contamination to sample; as compared with the molecular combing technique, it has better aligning effect and reproducibility. Combination of this kind of DNA molecular manipulating technique with the single DNA molecule detecting technique by atomic force microscopy and fluorescence microscopy will play an important role in the basic research of molecular dynamics and the application of gene research.     

Atomic force microscopy in cell biology

The history, characteristic, operation modes and coupling techniques of atomic force microscopy （AFM） are introduced. Then the application in cell biology is reviewed in four aspects： cell immobilization methods, cell imaging, force spectrum study and cell manipulation. And the prospect of AFM application in cell biology is discussed.     

AFM纳米操纵中侧向推动力的测量方法

纳米级操纵技术是制造纳米级结构、器件的重要方法之一,同时也是研究纳米粒子之间相互作用的重要手段.该文在运用原子力显微镜的探针操纵碳纳米管的同时,开发了一种纳米级操纵力的同步测量方法.应用该方法,成功测量出了操纵、切割碳纳米管的侧向力信息,从而为研究纳米粒子、基体与操纵工具之间的相互作用提供了最直接的力学信息和实验结果.在此基础上,可以进行初步的纳米设计,研究纳米新材料的力学特性.     

Atomic force microscopic observation on substructure of pollen exine inCedrus deodara andMetasequoia glyptostroboides

The substructure of pollen exine inCedrus deodara (Roxb.) Loud. andMetasequoia glyptostroboides Hu et Cheng has been examined with an atomic force microscope (AFM). The results indicate that the exine substructure units containing sporopollenin in two species are similar in shape, which are granular, but slightly different in size. InCedrus the substructure unit of pollen exine appears to be 56–99 nm long and 42–74 nm wide, while inMetasequoia it appears to be 81–118 nm long and 43–98 nm wide. It has been observed that the subunits of pollen exine inCedrus arranged tightly to form short-rod-like or spheroidal pollen exine units, several or more than ten of which formed an island-like structure. There are various spaces among these island-like structures which are interconnected to occupy the entire pollen exine. InMetasequoia, the subunits of pollen exine also arranged tightly with a distribution tendency of cluster of 3–10, however, no obvious boundary exists among these clusters. From our results, it is concluded that there is no tendency of helical arrangement for the subunits of pollen exine inCedrus andMetasequoia, and the results support Southworth’ view that subunits of pollen exine are granular shape in lattice structure.     

Real time observation of the photocleavage of single DNA molecules

A method for real time observation of photo-cleavage of stratched λDNA at single molecular level by a fluorescent microscope coupled with CCD is developed.DNA molecules stained with YOYO-1 are stretched by the mo-lecular combing technique and fixed on a modified slide.Then the Process of Photocleavage and relaxation of DNA under radiation of blue light is observed.We speculate that the conformation change of stretched DNA and the effect of water are likely to facilitate the effect of YOYO photocleav-age DNA molecules.The photocleavage effect of YOYO for stretched DNA may be useful to study DNA elasticity,cancer research as well as the interaction between DNA and dyes.     

Transmission electron microscopy and atomic force microscopy characterization of nickel deposition on bacterial cells

Recently bacterial cells have become attractive biological templates for the fabrication of metal nano- structures or nanomaterials due to their inherent small size, various standard geometrical shapes and abundant source. In this paper, nickel-coated bacterial cells (gram-negative bacteria of Escherichia coli) were fabricated via electroless chemical plating. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) characterization results reveal evident morphological difference between bacterial cells before and after deposition with nickel. The bare cells with smooth surface presented transverse outspreading effect at mica surface. Great changes took place in surface roughness for those bacterial cells after metallization. A large number of nickel nanoparticles were observed to be equably distributed at bacterial surface after activation and subsequent metallization. Furthermore, ultra thin section analytic results validated the presence and uniformity of thin nickel coating at bacte- rial surface after metallization.