甘薯(Ipomea batatas)、仙人掌(Opuntia dillenii)和芝麻(Sesamum orientale)丛枝病病原物的研究

1985年夏季,采集到甘薯(Ipomea batatas)、仙人掌(Opuntia dillenii)和芝麻(Sesamum orientale)的丛枝病标本,超薄切片用透射电子显微镜观察。同时甘薯丛枝病材料还进行了扫描电子显微镜的观察。结果从甘薯和仙人掌的病枝超薄切片的筛管细胞中观察到典型的类菌原体(MLO)菌体,在芝麻超薄切片的导管细胞中观察到类细菌(BLO)的菌体。甘薯丛枝病扫描电镜的观察,也观察到筛管细胞中圆形的类菌原体。     

游离细胞的扫描电镜标本制备

制备游离细胞的扫描电镜标本是比较复杂的。有人采用滤过器;也有人用阳离子(Polrcation)膜吸附细胞。这两种方法都有难以克服的不足之处。我们为了观察白血病细胞(HL—60),在设备、试剂不具备的条件下,摸索出一个比较简便的滤纸折叠过滤法。使其细胞分散均匀,贴附牢固,结构清晰,立体感强,不放电,无污染,无挤压损伤。既可对细胞进行低倍分类统计,又能进行高倍形态学研究。游离细胞的扫描电镜标本制备方法已有两种报导:一是采用抽滤瓶将标本过滤;二是用多聚阳离子(Polrcatjon)膜吸附标本。这两种方法都各有不足。一是抽力过大使标本受机械损伤或者在抽滤标本时,使标本空气干燥;二是吸附标本的数量不足,影响观察。如不具备这两种条件,实验更无法进行。最近我们应用培养的白血病细胞(HL—60)制备了扫描电镜标本,在扫描电镜观察到:细胞分散均匀,贴附牢固,结构清晰,无污染、不放电。既可进行细胞的低倍分类统计,又能进行高倍形态学观察。方法简便,效果较好。     

一种磨砂玻璃作为细菌载体进行扫描电镜观察的方法

通过对多种细菌材料的超微形态观察实验,优化出一种以磨砂玻璃作为黏附载体对细菌进行扫描电镜观察的新方法。该方法主要包括收集菌体、二重漂洗、加压黏附、固定、脱水、置换、临界点干燥、粘台、离子溅射和观察等步骤,创新点集中体现在采用磨砂玻璃作为黏附菌体的载体,同时,通过离心加压的方法提高菌体对玻璃表面黏附的牢固性。该方法可操作性强,实际观察效果优良,稳定性好,具有一定的借鉴意义。     

革兰氏阴性细菌细胞表面产物的超微结构

在超薄切片中,可以见到某些革兰氏阴性细菌的细胞表面,存在着结构不同的产物。大多数细菌的细胞表面产物为外膜泡(Outer-membrane),呈球状和管状,或为球-管联合体,都是由外膜构成的空泡或液泡(图1)。霍乱弧菌的外膜泡与众不同,为3-8个致密层构成的多层外膜泡,中空或内含小泡(图2)。钩端螺旋体的细胞表面产物,则是一种特有的螺管结构(Coil structure),或称脊柱体(spine),以外膜为鞘,内包一个粗38nm,长2000-3800nm的弹簧样小体(图3)。多形类杆菌的细胞表面,有两种结构;一种是不常见的微细胞(Minicell),具有细胞壁,细胞膜和细胞质等基本的细胞结构(图4);另一种是首次观察到的分泌性环层体(Concentric lamina)直径45-170nm,由同心环构成,无膜包被(图     

福氏2a痢疾杆菌膜抗原的免疫电镜定位

本文报告应用抗福氏2a痢疾杆菌膜成份McAb及胶体金探针对细菌膜抗原进行了定位。结果显示4种抗脂多糖McAb(3A6、2E6、4F1、2A3)可不均一的识别位于细菌壁表面的抗原,而另外一种抗LPS的McAb种(1G8)和一种抗膜蛋白McAb(1A1)识别的抗原未暴露于细菌表面。应用细菌膜碎片包埋前染色成功定位了抗膜蛋白McAb(1A1)位于细菌内膜的抗原。与McAb的生物活性比较表明阳性标记细菌表面抗原的McAb的抗原与其阻段志贺氏菌接触性溶血试验和对小鼠的被动保护力密切相关。提示免疫电镜标记技术确定LPS抗原表位在细菌表面的可及性和拷贝数对构建和筛选痢疾工程菌苗具有重要意义。     

抗生素产生菌菌落扫描观察样品制备法

利用电子显微镜研究经分离培养出来的各种抗生素产生菌菌体的表面纹饰结构以及形态特征进行分类鉴定等，已有文献资料介绍，其制备方法多采用无荫蒸馏水稀释法和常规的扫描电镜样品制备法。我们经过实践认为以上两种方法均很难反映出菌落自然生长的形态及菌体的形貌特征。     

扫描电镜样品制备的改进方法用于纤毛虫特氏前口虫皮层的观察

人们观察纤毛虫或其他细胞表膜内表面结构的方法是利用透射电镜.但观察到的均为二维图像,展示其形态结构的三维图像尚未有过报道.本文介绍了本实验室在扫描电镜样品制备的破膜方法基础上,在特氏前口虫上的新改进.此改进的方法展示了应用于特氏前口虫后,所获得的表膜内表面皮层下三维立体结构观察的效果,从而为相关领域的研究者应用扫描电镜...     

新发现的几个微生物超微结构

在用电镜系统地观察大量的细菌超薄切片标本中,偶然发现了几个新的超微结构。例如霍乱弧菌的多层外膜泡(multilayer outer-membrane);钩端螺旋体的各种球状体(various spheroid),以及支原体的细胞内出芽(intracellular budding)。材料和方法:一,材料:所用菌种分别由各类细菌专业实验室提供,于培养至既定时间取样。二,方法:从固体培养基上刮取菌苔,或从液体培养物中离心分离菌体。用戊二醛和四氧化饿固定,系列乙醇脱水,Epon812树脂包埋,LKB超薄切片机切片,乙酸双氧铀和柠檬酸铅染色,H-660透射电镜观察。     

石墨烯的氧化与抗菌特性

氧化石墨烯(GO)的抗菌机制(破坏细菌结构、氧化应激和阻断细菌传输)只从宏观角度论述了 GO整体结构对细菌的作用,但未能说明表面官能团对抗菌的贡献.在不同气氛(N2或O2)下退火对石墨烯进行表面官能团修饰,得到表面官能团组成不同的氮气处理石墨烯(NTG)、氧气处理石墨烯(OTG).平板菌落计数法抗菌测试表明,OTG有更...     

高山被孢霉的扫描电镜观察

本文对三株高山被孢霉(Mortierella alpina)菌株200012201、88335和87649进行了研究。PDA(potato dextrose agar,马铃薯葡萄糖琼脂培养基)平板观察,200012201菌株的菌落呈波浪状或高山状,菌丝为白色;扫描电镜观察,菌丝发达,分支繁密,很少发现孢囊孢子,但观察到少量的高山被孢霉接合孢子。而88335和87649菌株的PDA平板的菌落平铺于表面,菌丝白色,呈绒毛状;扫描电镜观察,与200012201菌的菌丝相比,菌丝较细,同样分支繁密,容易观察到大量由菌丝梗分化产生的成串的分生孢子。     

Scanning electron microscopy of food-poisoning bacterium Bacillus cereus using a variable-pressure SEM

A variable-pressure scanning electron microscopy (VP-SEM) with a cooling stage permits long hours of observation of water-containing specimens in their natural or close to natural state, without the conventional specimen preparations of fixation, dehydration, drying and metal coating. It reduces water vaporization and beam damage by keeping the specimens at a low temperature. We observed Bacillus cereus colonies on nutrient agar, which would shrink significantly if any conventional specimen preparation technique were used. We also studied the growing process of the bacteria on raw and steamed rice using the VP-SEM without conventional preparation techniques. Original specimens were directly mounted onto specimen holders and their backscattered electron images observed under the following conditions: specimen stage temperature, -10 degrees C; specimen chamber vacuum level, 30-70 Pa; and accelerating voltage, 15-20 kV. We recognized that the VP-SEM minimized deformation of the colonies due to shrinkage of the nutrient agar, and successfully imaged the morphology of the colonies and bacteria without a decline in bacteria number, which is apt to occur during fixation and dehydration. Also, the growth process of the bacteria on raw or steamed rice could be observed promptly, since there is no specimen preparation step.     

Au-TiO2纳米复合膜电极的光电化学性能及其表面形貌

应用绿色激光研究了Au-TiO2纳米复合膜电极的光电化学行为,发现Au-TiO2复合膜电极在Na2SO4溶液中对532 nm的可见光表现出良好的阳极光电流响应,光电流随电极电位的增加而增大.可见光激发下产生光电流的主要原因在于金粒子的表面等离子体共振吸收.SEM的观测实验表明电极表面存在纳米孔洞,这些纳米孔洞是金基底在煅烧过程中产生的.     

Development of a technique for high resolution electron microscopic observation of nano-materials at elevated temperatures

A technique for high resolution transmission electron microscopic (TEM) observation of nano-materials at very high temperatures has been developed. A spirally wound tungsten wire, normally used as the heating element of a high resolution-high temperature-specimen heating holder, was coated with a thin carbon film and the carbon film was used as the substrate of nanometer-sized specimen. The carbon film was securely self-adhered on the heater and the form of the carbon film remained unchanged until the tungsten heater is heated to around 1173 K. Temperature distribution on the carbon film has been measured by observing the sublimation of ZnS particles. Behavior of gold atoms on a surface of gold nano-particles dispersed on the carbon film has been clearly observed at 773 K in a scanning transmission electron microscope (STEM).     

类石墨薄膜的场致电子发射研究

利用脉冲激光烧蚀技术在硅衬底上制备了类石墨薄膜，以该薄膜为阴极进行了场致电子发射实验。当在阴阳极之间加电场后，两极之间出现了放电现象。放电之后．类石墨薄膜的阈值电场大大降低了．当电场为20V／μm时．该薄膜的发射点密度可以达到10^6/cm^2。利用Raman光谱、扫描电镜和X射线光电子谱对薄膜的表面形貌和微结构进行了测试．薄膜中的类石墨微结构对该薄膜的场致电子发射特性起了促进作用．场致电子发射实验显示类石墨薄膜作为冷阴极电子材料具有潜在的应用价值。     

退火态Cu膜表面形貌的分形特征

用磁控溅射工艺在Si基片上沉积500nm厚Cu膜,并在不同温度下进行快速退火处理。用扫描电镜（SEM）与原子力显微镜（AFM）观察薄膜表面形貌,并根据分形理论予以定量表征。结果表明：当退火温度T在小于673K范围内增加时,分形维数Dr逐渐减小;而当T增加至773K时,Dr异常增加。本文根据表面扩散、晶粒长大、缺陷形成等机制对其进行了分析。     

A scanning electron microscope study of electromigration in an Al-2% Cu thin film

Electromigration in an Al-27% Cu metallization thin film deposited on a silicon transistor structure has been studied in situ using the electron beam induced current mode (EBIC) of the scanning electron microscope. In this mode electrons which are transmitted through the metallization generate a signal which depends on the thin film thickness and its mass density. During the initial stages of the electromigration experiment the copper rich precipitates on the surface coarsened. Also, there was a preferential coarsening towards the positive end. Once the negative end became depleted of these surface precipitates grain thinning occurred. Voids nucleated and grew in from the sides of the metallization in these depleted regions finally causing film failure. However almost no voids were observed at grain boundaries or triple points. The copper rich precipitates in the interior of the metal film were stationary and showed no signs of coarsening or depleting any region. These observations suggest that surface diffusion is the predominant mode of atom migration in these alloys; grain boundary diffusion has been reduced compared to pure aluminum.     

4H-SiC表面热氧化生长SiOx薄膜特性的研究

采用扫描电子显微镜（SEM）、原子力显微镜（AFM）和X射线光电子能谱（XPS）测试方法对4H-SiC上热氧化生长的氧化硅（SiOx）薄膜表面形貌进行观测，并分析研究SiOx薄膜和SiOx/4H-SiC界面的相关性质，包括拟合Si2p、O1s和C1s的XPS谱线和分析其相应的结合能，以及分析SiOx层中各主要元素随不同深度的组分变化情况，从而获得该热氧化SiOx薄膜的化学组成和化学态结构，并更好地了解其构成情况以及SiOx/4H-SiC的界面性质。     

Thickness dependent structural and optical properties of In/Te bilayer thin films

In_xTe_y thin films have been prepared from In/Te bilayer by sequential thermal evaporation. The samples were analyzed by x-ray diffraction (XRD), optical transmittance spectra and scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) in order to investigate structural, optical properties, surface morphology and elemental composition of the prepared films. XRD spectra reveal that all films exhibit mixed phases of In₂Te₃ and In₂Te₅. Increase in grain size with film increase in thickness was observed. The surface was highly porous as observed by SEM analysis. Band gap energy of In_xTe_y system is found to decrease with increase in film thickness.     

电子束蒸发沉积TiN薄膜的电学特性研究

采用TCP(Transverse coupled plasma)等离子体辅助电子枪蒸镀技术,在玻璃衬底上制备了TiN薄膜。用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究了不同工艺条件对薄膜晶体结构和表面形貌的影响;用四探针法测量薄膜的电阻率变化。结果表明,所制备的TiN薄膜在(111)晶面有择优取向。与金属薄膜类似,TiN薄膜的平均表面粗糙度与电阻率之间存在近似线性关系,并且电阻率随残余应力增大而增大。     

Electron Emission Properties of Surface-Conduction Electron Emitters With a PdO-C-PdO Multilayer Conductive Film Deposited by Magnetron Sputtering

Conductive films are an essential component in surface-conduction electron emitters (SCEs), and they have a major influence on the electron emission properties of SCEs. In this work, a novel PdO-C-PdO multilayer film deposited by magnetron sputtering is proposed as the conductive film in SCEs. Three SCE cathodes with this type of multilayer film were fabricated, together with three other SCE cathodes with a PdO single-layer film used as a reference. For these cathodes, the dependences of the conduction current and the emission current on the device voltage and the anode voltage were measured, and the luminescence patterns were observed after the electroforming and activation processes of the conductive films had occurred. The surface morphologies of the conductive films were analyzed by scanning electron microscopy. The results indicate that the SCEs with the PdO-C-PdO multilayer conductive film have better electron emission properties compared with the SCEs with the PdO single-layer conductive film. For an anode voltage of 2 kV and a device voltage of 14 V, the emission current and the electron emission ratio of the SCEs with the PdO-C-PdO multilayer film can reach 179.5 μA and 2.2‰, respectively.