Identification of functional connections between calmodulin and the yeast actin cytoskeleton

For scarce antigens or antigens which are embedded in a dense macromolecular structure, on-section labeling, the first method of choice, is not always successful. Often, the antigen can be localized by immunofluorescence microscopy, usually by a pre-embedding labeling method. Most of these methods lead to loss of ultrastructural details and, hence, labeling at electron microscope resolution does not add essential information. The scope of this paper is to compare five permeabilization methods for pre-embedding labelling for electron microscopy. We aim for a method that is easy to use and suitable for routine investigations. For our ongoing work, special attention is given to labeling of the cell nucleus. Accessibility of cytoplasmic and nuclear antigens is monitored with a set of different marker antibodies. From this investigation, we suggest that prefixation with formaldehyde/glutaraldehyde is necessary to stabilize the ultrastructure before using a detergent (Triton X-100 or Brij 58) to permeabilize or remove the membranes. The experimental conditions for labeling should be checked first with fluorescence or fluorescence-gold markers by fluorescence microscopy. Then either ultrasmall gold particles (with or without fluorochrome) with silver enhancement or, if the ultrasmall gold particles are obstructed, peroxidase markers are advised. The most promising technique to localize scarce antigens with good contrast is the combination of a pre-embedding peroxidase/tyramide-FITC or -biotin labeling followed by an on-section colloidal gold detection.     

大型塔式磨机在金精矿氰化细磨中的应用

塔式磨机是一种垂直安装、筒体固定及内带螺旋搅拌装置的搅拌型细磨设备。由于金精矿中金、银颗粒比较细,金、银矿物大多以连生体和包裹体形式与黄铁矿共存,需要对金精矿进行充分研磨,提高磨矿细度,使金、银颗粒充分裸露,达到单体解离的效果。在金精矿氰化过程中,解离度的大幅提高,可使金、银浸出彻底,氰化回收率随之提高。塔式磨机具有能耗低、磨矿粒度细、噪音低、占用空间少、易维护、便于安装及磨矿效率高等优点,因此是金精矿氰化细磨的理想磨机。     

Backscatter electron imaging of double immunogold labeled erythrocytes using two primary monoclonal IgM antibodies

The majority of mouse monoclonal antibodies reacting with blood group epitopes on erythrocytes are of the IgM class, have equal light chain type, and are available as culture supernatants only. To study the interrelationship of the blood group antigens, a method is presented which allows double labeling applying two unconjugated monoclonal antibodies of the same class and species. The method comprises two indirect, sequential labelings using mouse IgM anti-A and anti-H as primary antibodies and two goat anti-mouse IgM conjugated to 30 and 20 nm colloidal gold particles as secondary antibodies. After labeling for the first antigen, free binding sites on the primary antibody are blocked by incubation with an unconjugated goat anti-mouse antibody. The free anti-species on the secondary antibody, conjugated to 30 nm gold particles, are inactivated by silver enhancement. The silver enhancement also enlarges the gold particle for optimal discrimination between the two particle sizes, which are chosen accordingly. Semiquantitations of double labeled cells from subgroup A2 and A3 were found to be in good agreement with the counts of the corresponding single labelings as well as between experiments, irrespective of which of the two antibodies was applied in the first labeling sequence. The results were in accordance with a reciprocal but nonlinear relationship between the A and H antigens and suggest different affinities of the two antibodies for the epitopes in the subgroups investigated, indicating different biochemistry of the antigen determinants.     

胶体金-SPA复合物的制备

研究了直径15nm胶体金的制备方法，制得金标记葡萄球菌蛋白A(SPA)，并对其活性进行了研究。所制得的胶体金探针稳定、可靠，有较好的生物活性。     

粗金粉中金和银的联合测定

运用传统的火试金法处理粗金粉样品,建立了重量法测定粗金粉中金量、火焰原子吸收光谱法测定银量的新方法。采用留铅灰吹的方法使样品中的金银富集在1~2 g的铅合粒中,用HNO₃溶解铅合粒,然后采用重量法测定金量,火焰原子吸收光谱法于波长328.1 nm测定银量。本方法有效地解决了粗金粉中金银不能联合测定的难题,银的方法检出限为0.003 1 μg/mL。将该法用于实际样品分析,测定结果与国标法测定结果一致,金的相对标准偏差≤0.07 %,银的相对标准偏差≤1.2 %,且金和银的银回收率分别为100 %和98 %~101 %之间。     

Sulphated glycosaminoglycans in guinea pig eosinophils studied by means of cationic colloidal gold

Using bone marrow embedded in hydrophilic resin Lowicryl K4M and cationic colloidal gold pH 1.0 labelling, we studied sites of sulphation and sulphated glycosaminoglycans ultrastructurally in various maturational stages of both eosinophil granulocytes and eosinophil granules of guinea pig. Eosinophil granules reacted positively to cationic gold, the pattern of labelling varying according to the degree of cell maturation. The formation of eosinophil granules takes place throughout the myelocyte stage. Early eosinophil myelocytes contain a large Golgi apparatus with active granulogenesis, while late ones contain a small and less active Golgi apparatus. All the immature granules were labelled positively. However, mature granules with a central crystal bar lost their affinity towards colloidal gold. Interestingly, strong colloidal gold labelling was also observed in the trans to transmost Golgi apparatus, especially in immature eosinophil granulocytes. This indicates that sulphation of glycosaminoglycans occurs in the trans to transmost Golgi apparatus of eosinophil granulocytes. Prior absorption with poly-L-lysine prevented colloidal gold labelling of tissue sections. Methylation of sections at 37 degrees C did not alter the gold labelling, whereas the labelling disappeared after methylation at 60 degrees C. Prior treatment with chondroitinase ABC or heparinase I abolished the majority of colloidal gold labelling in immature eosinophil granules. Taking these results together, we conclude that immature eosinophil granules contain sulphated glycosaminoglycans including chondroitin sulphate or heparan sulphate or both.     

Optical slicing and 3-D characterization of hippocampal capillaries in the rat visualized by autometallographic silver enhancement of colloidal gold particles

In order to visualize the vascular system of the rat brain, 10 Wistar rats were perfused transcardially with glutaraldehyde and a 40 degrees C gold-gelatine solution. The brains were post-fixed with glutaraldehyde and vibratomized into 100-micron-thick slices, and the gold particles were developed by autometallography. In this way, the colloidal gold particles in the vessels became encased in silver and thereby made visible. The developed gold staining is stable and does not interfere with further dehydration and counterstaining. Images were frame grabbed during optical slicing, and classic stereograms and 'shadow' 3-D images were produced. We found a high variation of capillary density in the hippocampal region reflecting known subregional structures. The silver-enhanced vessels acted as natural markers and made it possible to study and measure aspects of the complexity of dehydration and staining artifacts. We found a non-linear shrinking of 13-17% in the x- and y-directions and a spatial shrinking up to 50% in some regions after the dehydration and staining process. This observation may be of interest not only in relation to tissue subjected to this fixation protocol but also to other fixation procedures. The gold-gelatine autometallographic technique and the present stereograms can release data for stereological use as well.     

Widths of transverse momentum distributions in intermediate-energy heavy-ion collisions

The need to include dynamical collision momentum transfer contributions, arising from interacting nuclear and Coulomb fields, to estimates of fragment momentum distributions is discussed. Methods based upon an optical potential model are presented. Comparisons with recent experimental data of the Siegen group for variances of transverse momentum distributions for gold nuclei at 980 A MeV fragmenting on silver foil and plastic nuclear track detector targets are made. The agreement between theory and experiment is good.     

某含金银铜矿石工艺矿物学研究

对某含金、银、铜矿石的研究重点是查明矿石工艺性质,金矿物、银矿物及铜矿物在矿石中嵌存状态、嵌布粒度等工艺特性。同时,对金矿物、银矿物组成及超出显微镜分辨能力的次显微金、银采用扫描电镜进行系统研究。矿石的工艺矿物学研究为选矿工艺流程和条件试验的确定提供可靠数据,以期选矿试验金、银、铜获得理想的回收指标。     

免疫检测用纳米胶体金的制备及粒径控制

利用柠檬酸钠作为还原剂,采用液相还原法制备了适用于免疫检测的胶体金纳米颗粒。用透射电子显微镜和紫外/可见光分光光度计分别对胶体金颗粒的形貌和光学吸收特性进行了检测。结果表明,柠檬酸钠的加入量是影响胶体金颗粒粒径和形貌的主要因素,制备100ml0.01%胶体金溶液,1%柠檬酸钠溶液加入量小于5ml时,胶体金颗粒的平均直径随柠檬酸钠加入量的增加而减小,当大于5ml时,胶体金颗粒的平均直径随柠檬酸钠量的增加而增大。在研究范围内,胶体金颗粒的平均粒径与最大吸收峰波长之间存在直线回归关系。制备的胶体金呈单分散的球形分布,具有较高的生物学活性,适用于胶体金免疫检测。     

Recovery of Silver and Gold from Cyanide Solution by Magnetic Species Formed in the Electrocoagulation Process

Cyanidation is the predominant process by which gold and silver are recovered from their ores in metallurgical operations, and it is recognized that the Carbon in Pulp, the Merrill–Crowe, the Ion Exchange, and Solvent Extraction processes are used for concentration and purification of gold and silver from cyanide solutions. Among other available options for recovery of precious metals from cyanide solutions, Electrocoagulation (EC) is a very promising water and wastewater electrochemical technique that does not require high concentrations of silver and gold in cyanide solutions to yield excellent results. In this work, an introduction to the fundamentals of the EC process is given, followed by the conditions and results of the EC test run for removal of precious metals from cyanide solutions, and finally the characterization of the solid products formed during the EC process with X-ray Diffraction, SEM, and Transmission Mossbauer Spectroscopy. Results suggest that magnetite particles and amorphous iron oxyhydroxides are present (Lepidocrocite and Gohetite). With the EC process, the achieved removal efficiency of silver and gold from cyanide solutions, within 5 min, exceeded 99%.     

火试金重量法测定石英砂中金含量

对采用火试金重量法对石英砂中金含量进行检测的实验条件进行了研究,重点对火试金熔融的配料方案、样品中银量对分金的影响、重量法和原子吸收法测定金量的误差来源等方面进行了考查。实验结果表明:该方法的精密度好,准确度高。该方法适用范围在1.0～10.0g/t之间。     

Characterization of nanostructured materials using SEM and HREM techniques

A microstructural characterization based on analytical scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HREM) was carried out on nanostructured M50-type steel and also on nanometer-sized gold particles. Both nanostructured materials were prepared with different chemical methods recently reported in the literature. The obtained nanostructured steel powders were subsequently consolidated into bulk samples. The SEM studies of the M50 compound probes show the presence of pores of different sizes. The composition of the specimens indicates small differences with the M50-type steel alloy, with strong variations of the vanadium amount in the cavities of the compound. The HREM images show the presence of small precipitates in the range of a few nanometers in size. The structural characteristics of the grain boundaries between the nanometric crystallites were also explored. The geometrical relationships between adjacent alpha-Fe grains were obtained for some particular boundary arrangements. The nanometric gold particles show diameters which vary from 4 to 11 nm. Some of these particles display twin boundary arrangements. The nature of these twin arrangements was also explored. Theoretical simulations based on the multislice theory of the electron diffraction dynamical theory were carried out mainly to explore the nature of the twin boundaries obtained in the gold particles. Comparisons between the simulated images and the experimental results are presented.     

青海抗得弄舍金多金属矿床金银的赋存状态研究

通过显微镜及电子探针分析手段对青海抗得弄舍金多金属矿床金矿石中金、银的赋存状态进行详细的研究。结果表明,矿石中金矿物主要为银金矿,其次为自然金,嵌布状态以粒间金为主,其次为包裹金和裂隙金;银矿物以银金矿为主,其次为自然银,部分以类质同像形式赋存于黝铜矿中;主要载金、银矿物有闪锌矿、方铅矿、黄铜矿、黝铜矿、黄铁矿、褐铁矿、重晶石、石英等。对金银赋存状态的研究为选矿工艺设计及探讨矿床成因提供了依据。     

湿化学法制备微米级枝状银粉及其生长机理研究

采用抗坏血酸在40℃下还原硫酸铜制备微米铜粉,利用所制备的铜粉与硝酸银溶液反应制备出枝状的微米级银粉,并对枝状银粉的形成机理进行研究.通过SEM和XRD对制备的铜粉和银粉进行表征.结果表明:制备的新鲜铜粉为颗粒状,直径为3～10 μm,具有明显的棱角;制备的银粉为树枝状,长度为5～25.μm;而且当硝酸银浓度、硝酸银/铜粉摩尔比或反应温度较高时,更易生成枝状晶体,但当它们过高时,枝状晶体的二级结构变窄,三级结构逐渐消褪.枝状银粉的形成机理很可能是由于在铜粉表面具有高表面自由能的地方形成银核心,银粒子在此核心周围聚集,在非平衡态下,粒子扩散受动力学控制,自发聚集成高度有序的枝状结构.     

贵州水银洞含金黄铁矿中金的赋存形式探讨

采用扫描电子显微镜和电子探针等手段,对贵州水银洞金矿中黄铁矿进行形貌观察和成分测定,结果表明,黄铁矿具有草莓状、立方体、五角十二面体及胶状等多种形态,其中,五角十二面体和胶状黄铁矿含金,且金与砷含量存在一定的关系。从量子化学计算和最紧密堆积原理探讨金进入黄铁矿晶格中的情况：金以Au+进入晶格中,替代S位比替代Fe位更容易,而且当黄铁矿中含砷时,有利于金进入晶格,但并非含砷越高,含金就越高。当含砷量在一定范围内,含砷高,含金也高;当含砷量超过某一值,反而不利于金进入晶格。     

东昆仑阿斯哈金矿胶状黄铁矿成因及其成矿意义

东昆仑成矿带沟里金矿区阿斯哈金矿床中的黄铁矿主要分为两类：早期自形结晶黄铁矿和晚期胶状黄铁矿。为了厘清阿斯哈金矿胶状黄铁矿成因及其成矿意义,本文对具有特殊意义的胶状黄铁矿开展原位微量元素分析、面扫分析和原位硫同位素分析。结果表明：胶状黄铁矿富As、Au、Pb和Cu,贫Co和Ni,Co/Ni比值大于10,δ³⁴S值范围变化较窄（+6.1‰~+6.8‰）。结合显微结构,认为胶状黄铁矿为岩浆热液成因,与阿斯哈金矿区内隐伏花岗闪长斑岩体可能存在密切成因联系。迅速沉淀于温度骤降条件下的胶状黄铁矿中的As和Au发生了解耦,微米级粒径黄铁矿为控制固溶体金富集的主导因素。     

Structure of hydrated oligonucleotides studied by in situ scanning tunneling microscopy

We have used the scanning tunneling microscope (STM) to image several synthetic oligonucleotides adsorbed onto a positively charged Au(111) electrode. The molecules were deposited and imaged in aqueous electrolyte under potential control, a procedure that eliminated the problem of the substrate artifacts that had limited some previous STM studies. Experiments were carried out with two types of single-stranded molecules (11 and 20 bases long) and three types of double-stranded molecules (20 and 61 base pairs and 31 bases with 25 bases paired and 6-base "sticky" ends). The molecules lie along symmetry directions on the reconstructed (23 x square root of 3) gold surface, and length measurements indicate that they adopt simple base-stacked structures. The base stacking distances are, within experimental uncertainty, equal to the 0.33 nm measured for polymeric aggregates of stacked purines by direct imaging in identical conditions. The images show features consistent with helical structures. Double helices have a major-groove periodicity that is consistent with a 36 degrees twist. The single helices appear to be more tightly twisted. A simple tunneling model of STM contrast generates good agreement between measured and calculated images.     

Selective excitatory amino acid uptake in glutamatergic nerve terminals and in glia in the rat striatum: quantitative electron microscopic immunocytochemistry of exogenous (D)-aspartate and endogenous glutamate and GABA

To characterize glutamate/aspartate uptake activity in various cellular and subcellular elements in the striatum, rat striatal slices were exposed to 10 and 50 mu M exogenous (D)-aspartate. After fixation with glutaraldehyde/formaldehyde the distribution of (D)-aspartate was analysed by postembedding immunocytochemistry and the ultrastructural distribution was compared with the distributions of endogenous glutamate and GABA. Light microscopically, (D)-aspartate-like immunoreactivity was localized in conspicuous dots along very weakly labelled dendritic profiles and neuron cell bodies. At the electron microscope level gold particles signalling (D)-aspartate occurred at highest density in nerve terminals making asymmetrical contacts with postsynaptic spines (i.e. resembling synapses of cortical afferents). Astrocytic processes also contained gold particles, but at a lower density than nerve endings. In contrast, dendritic spines were only weakly (D)-aspartate-positive. The difference in labelling at 10 and 50 mu M (D)-aspartate was consistent with 'high-affinity' uptake. Neighbouring sections processed with other antibodies showed that the D-aspartate labelling. Occurred in nerve terminals strongly immunoreactive for glutamate, rather than in terminals very weakly glutamate-immunopositive or in nerve endings immunoreactive for GABA. Glutamate labelling of perfusion-fixed striatum confirmed that terminals forming asymmetrical synaptic contacts with spines were enriched with gold particles, suggesting that these terminals use glutamate as a transmitter. This study demonstrates that high-affinity uptake sites for excitatory amino acids in the striatum are most strongly expressed on presumed glutamatergic nerve terminals and on astrocytes.     

X-ray diffraction and computer simulation studies of the structure of [001] twist boundaries in AuAg alloys

A combined X-ray diffraction and Monte Carlo simulation study of the structure of Σ 13 [001] twist boundaries in gold-silver alloys, as a function of silver concentration is presented. Five alloy concentrations corresponding to 0, 25, 50, 75, and 100 at.% silver are studied. For the 50% alloy, a large number of absolute grain boundary structure factors are measured, both in the plane of the grain boundary and normal to it. At the other compositions fewer structure factors are measured. However, their magnitudes are found to be useful in setting limits on the extent of interfacial segregation. Generally good agreement is found between all measurements and calculations. For the 50% alloy it is concluded that the alloying with silver produces only very slight boundary segregation and changes in the positions of the substitutional sites in the boundaries (relative to that in pure gold) and that the gold and silver atoms are distributed on these sites almost randomly. Detailed information on atomic vibrations and individual site occupation probabilities is presented.