Cautions,common sense,and rationale for the electron microscopy laboratory

This paper is a condensation of precautions, general information, and common-sense tips designed to assist students in electron microscopy. Although not all circumstances are included and many of the recommendations are common sense, this handout has proven invaluable to beginners in two different multiuser electron microscopy facilities. When integrated by discussion and testing into the initial training period, this information will save the neophyte, lab manager, and others working in a multiuser facility untold hours of frustration, of wasted time, effort, and supplies, and of exposure to the myriad environmental hazards inherent in the performance of electron microscopy. The rationale for these suggestions is included, enhancing problem-solving in situations not covered directly in this presentation.     

Antiwear Behavior of ZDDP and Fluorinated ZDDP in the Presence of Alkylated Diphenyl Amine Antioxidants

Environmental regulations have called for a reduction of phosphorus content in engine oils in recent years. The anti-wear additive zinc dialkyl dithiophosphate (ZDDP), which is also an antioxidant, is one of the most important components of engine oil additives. ZDDP is a major source of phosphorus. One way to reduce phosphorus levels is to replace ZDDP with new environmentally friendly antiwear agents that have similar or superior wear performance compared to ZDDP. Another way to address the environmental issue is to reduce the amount of ZDDP in engine oils. At the same time, it is necessary to increase the efficiency of ZDDP by finding optimum conditions that would result in improved antiwear performance. The antiwear mechanism of ZDDP involves its degradation thermally and tribologically, leading to the formation of an antiwear film that consists of polyphosphates and sulphides. The structure of the antiwear film is almost similar in both types of degradation. But the breakdown efficiency of ZDDP is diminished by the parallel reaction of ZDDP with other additives, as well as the antagonistic effects of these additives. The new fluorinated ZDDP complex developed has shown better wear performance compared to ZDDP. This would allow the possibility of further reduction of phosphorus in engine oils compared to current levels. In this paper we study the interaction of ZDDP and fluorinated ZDDP with alkylated diphenylamine. The impact of antioxidant on wear performance was examined using a ball-on-cylinder tribometer. The interactions between ZDDP and the fluorinated ZDDP with the antioxidant were studied using NMR and the surface of the tribofilm was examined using SEM, TEM, and Auger spectroscopy.     

Effect of Deaeration and Controlled Environments on the Performance of Lubricants

The effect of oxygen in lubricants on the wear of camshaft lobes and followers was investigated under air and either argon or nitrogen environments. The motored valve train wear tester was used as a wear tester. White oil, white oil containing Zinc Dithiophosphate (ZDP), and REO 200 were used as lubricants. Hydroperoxide was used as a contaminant for the tests conducted with REO 200.

The results showed that the wear of camshaft lobes and cam followers decreased after deaeration. The tests conducted under argon showed a further decrease in wear. The specimens tested with white oil and white oil with ZDP were analyzed by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The operation of abrasive wear and oxidational wear was observed. A decrease in the hydroperoxide number under argon atmospheres was observed.     

Characterization of Cobalt Oxide and Calcium‐Aluminum Oxide nano‐catalyst through Scanning Electron Microscopy,X‐ray diffraction,and Energy Dispersive X‐ray Spectroscopy

The Cobalt Oxide and Calcium‐Aluminum Oxide nano‐catalysts were analyzed using Scanning Electronic Microscopy (SEM), X‐ray diffraction (XRD), and dispersive X‐ray spectroscopy (EDX) techniques. Preliminary results showed that the particles of Cobalt Oxide exhibit sponge like morphology and homogenous distribution as per confirmation via SEM. Its average particle size ranges to 30.6 nm demonstrating enormous number of pores and aggregative in nature. Its various peaks were ranging from 19.2 to 65.4 after XRD analysis. The highest intensity was observed at 36.9 position. The energy dispersive spectroscopy techniques were used to calculate the elements present in sample according to their weight and atomic percentage. The cobalt oxide contain cobalt as the most abundant element with 46.85 wt% and 18.01 atomic percent. It contain oxygen with 30.51 wt% and 43.19 atomic percent. Whereas, SEM of calcium aluminum oxide showed random morphology. According to the calculation of Scherrer equation regarding XRD analysis, it was distributed homogenously with particle size ranges from 30 to 40 nm. Its porous morphology was due to the interconnecting gaps between different particles. It result the eight peaks ranging from 18.1 to 62.7 in XRD spectrum. The highest intensity observed at 35.1 with average crystallite particle size of 25.6 nm. The calcium aluminum oxide contain aluminum 7.45 wt% and 6.93 atomic percent. The calcium was the most abundant element with54.7 wt% and 34.24 atomic percent followed by oxygen with 37.26 wt% and 58.42 atomic percent. It was concluded that the SEM, XRD, and EDX are the most significant techniques to characterize nano‐catalysts in particular and other compounds generally.     

电液自由锻锤锤头开裂失效分析

应用金相显微镜、扫描电镜、拉力试验机、冲击试验机、硬度计、光谱测试仪等通过宏观检查、尺寸检查、断口形貌分析、化学成分分析、机械性能试验、非金属夹杂物评级、金相组织分析等方法对某电液自由锻锤锤头开裂现象进行分析。分析结果表明锤头发生开裂的裂纹起始于燕尾槽槽底的R角处,开裂初始部位断口形貌显示有应力集中现象存在,锤头的开裂主要呈脆性断裂特征,裂纹扩展存在休止迹象。     

Flyability and Durability Test of Dynamic Fly-Height Sliders at 1-nm Clearance

The requirement of higher storage density in hard disk drives is pushing the head-to-media spacing(HMS) to become ever smaller. Currently, thermal protrusion at the transducer that is realized by the heating element in dynamic fly-height(DFH) sliders can be used to control the HMS by applying controllable electrical power. Thus, just how low the slider can fly stably and reliably using the DFH technology is a major concern for the hard-drive industry. This article describes a test for evaluating the flyability and durability of the head–disk interface(HDI) at desired and ultrasmall clearance using DFH sliders. Through such a test, the HDI flyability and durability at 1-nm clearance were examined using commercial DFH sliders with two specially designed air-bearing surfaces(ABSs). The possibility of stable and durable on-track flying at 1-nm clearance for optimized DFH sliders was demonstrated in an ambient environment.     

Erosion Debris Particle Observations and the Micromachining Mechanism of Erosion

Erosion debris particles produced by particle impact erosion of pure Ni and a stainless steel have been examined in the scanning electron microscope for the purpose of determining whether micro-machining is an operative mechanism of erosion by alumina particles. Macroscopic machining chips generally exhibit well-defined lamellae on the side of the chip away from the tool face, and such lamellae are also observed in micromachining chips produced by abrasion or scratch testing. The aspect ratio of such chips is generally large. In the present work, the aspect ratios and shapes of erosion debris particles formed at angles of incidence below the peak erosion angle (α_c) were generally consistent with the dimensions of the impact craters formed on the eroded surface and with the hypothesis that they were formed by micromachining. However, most of the debris particles did not exhibit characteristic lamellae. This may be explained by the fact that the surface from which they are formed is very rough even on a scale similar to the size of the debris particles. This is not true in abrasion: Micromachining chips formed from such a surface would be expected to have surfaces which would obscure the existence of lamellae. However, some chips would be expected to come from the few relatively smooth areas of the surface, and these should show lamellae. Examples of such chips were, indeed, found, and micrographs of these chips are nearly indistinguishable from micrographs of micromachining chips formed by abrasion or scratch tests. It is concluded that micromachining is an operative mechanism of erosion which is of greatest importance at low angles of incidence. Debris particles formed at higher angles of incidence are generally more platelike.     

The plant endoplasmic reticulum: an organized chaos of tubules and sheets with multiple functions

The endoplasmic reticulum is a fascinating organelle at the core of the secretory pathway. It is responsible for the synthesis of one third of the cellular proteome and, in plant cells, it produces receptors and transporters of hormones as well as the proteins responsible for the biosynthesis of critical components of a cellulosic cell wall. The endoplasmic reticulum structure resembles a spider-web network of interconnected tubules and cisternae that pervades the cell. The study of the dynamics and interaction of this organelles with other cellular structures such as the plasma membrane, the Golgi apparatus and the cytoskeleton, have been permitted by the implementation of fluorescent protein and advanced confocal imaging. In this review, we report on the findings that contributed towards the understanding of the endoplasmic reticulum morphology and function with the aid of fluorescent proteins, focusing on the contributions provided by pioneering work from the lab of the late Professor Chris Hawes.     

The Additive Action of Some Organic Chlorides and Sulfides in the Four-Ball Lubricant Test

When tested by the four-ball extreme-pressure procedure, oil solutions of t-octyl chloride at the 2 percent chlorine level rated approximately equal to oil solutions of di-t-octyl disulfide at the 2 percent sulfur level, and both of these additive blends rated better than n-octyl chloride in oil at the 2 percent chlorine level or di-n-octyl disulfide in oil at the 2 percent sulfur level. n-Octyl chloride and di-n-octyl disulfide in oil at corresponding concentrations of active element were approximately equivalent in additive action. t-Octyl chloride was almost as good at the 1 percent as at the 2 percent chlorine level. Mixtures of di-t-octyl disulfide and t-octyl chloride in oil at the level 1 percent S-1 percent Cl rated approximately twice as well as di-t-octyl disulfide (2 percent S) or t-octyl chloride (2 percent Cl). Some finer points of the action of these additives were investigated by studying time-connected behavior at 50-kg and 100-kg loads. The action of the additives cannot be explained on the basis of their chemical structures only; interactions with the rubbing process in the four-ball machine also must be considered.     

Frequency domain image analysis for the characterization of porous products

Many pharmaceutical products are obtained via freeze-drying of liquid solutions to obtain stable long lasting preparations. The freeze-dry process produces porous cakes whose structure strongly depends on the freezing phase, so that monitoring and optimizing this phase can help both reducing the product cost and insuring its constant quality. Nowadays the optimization is usually performed by determining the cake mass transfer coefficient via a costly process in pilot plants, while the quality is assured only by controlling the process conditions. This paper describes an alternative way of approximately estimating the mass transfer coefficient, which is based on the observation of the product structure by a simple electron microscope followed by a frequency domain imaging process. While the process has been designed and characterized specifically for pharmaceutical products, the proposed approach can be used in several other fields where the characteristics of porous material have to be monitored.     

Raloxifene-loaded and aptamer-bonded exosomes induce autophagic and apoptotic death in HeLa cells by enhancing the lysosomotropic effect

Background: Raloxifene, a selective estrogen receptor modulator, is also known to be a lysosomotropic agent. The bioavailability of raloxifene is around 2% due to extensive hepatic transport. Exosomes are nanosized vesicles that are naturally released from cells. Method: In this study, exosomes released from HeLa cervical cancer cells were loaded with raloxifene to increase its bioavailability, and an aptamer was attached to the exosome membrane for targeting only HeLa cells. Characterization of exosomes isolated from HeLa cells was performed by transmission electron microscopy, zeta sizer, and western blotting. In addition, the cytotoxic, apoptotic, autophagic, and lysosomotropic effects of the prepared Exo-Apt-Ral formulation on HeLa cervical cancer cells were investigated. Results: According to zeta analysis, the sizes of the empty exosome and Exo-Apt-Ral formulation were measured as 66 ± 12 and 120 ± 21 nm, respectively. There was a rise in the lysosomal permeability of HeLa cells after the Exo-Apt-Ral application. In addition, both apoptotic and autophagic death mechanisms were triggered in HeLa cells after the Exo-Apt-Ral application. Conclusion: This study showed that raloxifene functionalized by loading into aptamer-bound exosomes can be a new targeted drug carrier system for cervical cancer.     

Accumulation of fluorescent non-cationic probes in mitochondria of cultured cells: observations,a proposed mechanism,and some implications

Cultured rat fibroblasts were exposed to millimolar concentrations of forty-four non-cationic fluorescent probes, of very varied physico-chemical properties. Mitochondrial staining occurred with nineteen of these probes, nine of which were nominally anionic and ten nominally non-ionic. All nineteen were in fact lipophilic weak acids. Using structural parameters these could be specified numerically as follows: electric charge ≤ 0; log P(less-ionized form) < 0; and pKa ～ 7. In addition to these structural variables, dye concentration and the time of exposure of cells to probes were significant factors for the staining of mitochondria. Accumulation of these compounds can be understood in terms of ion-trapping of hydrophilic salts of lipophilic weak acids, due to the internal pH of respiring mitochondria being higher than the cytosolic pH. As a case example of the application of this approach, the mode of action of many inhibitors of mitochondrial anabolism is discussed in terms of the mechanisms introduced here.     

Electron crystallography applied to the structure determination of Nb(Cu,Al,X)2 Laves phases

The presence of primary precipitates of the Laves phases considerably improves the mechanical properties and the resistance to thermal degradation of the high‐temperature shape memory Cu–Al–Nb alloys. The structure analysis of the Laves phases was carried out on particles contained in the ternary and quaternary alloys as well on synthesized compounds related to the composition of the Nb(Cu,Al,X)₂ phase, where X = Ni, Co, Cr, Ti and Zr. The precise structure determination of the Laves phases was carried out by the electron crystallography method using the crisp software.     

A new approach for high-pressure freezing of primary culture cells: the fine structure and stimulation-associated transformation of cultured rabbit gastric parietal cells

A newly designated procedure for high‐pressure freezing of primary culture cells provided excellent ultrastructure of rabbit gastric parietal cells. The isolated parietal cells were cultivated on Matrigel‐coated aluminium plates for conventional subsequential cryoimmobilization by high‐pressure freezing. The ultrastructure of different organelles (Golgi apparatus, mitochondria, multivesicular bodies, etc.) was well preserved compared to conventional chemical fixation. In detail, actin filaments were clearly shown within the microvilli and the subapical cytoplasm. Another striking finding on the cytoskeleton system is the abundance of microtubules among the tubulovesicles. Interestingly, some microtubules appeared to be associating with tubulovesicles. A large number of electron‐dense coated pits and vesicles were observed around the apical membrane vacuoles in cimetidine‐treated resting parietal cells, consistent with an active membrane uptake in the resting state. Immunogold labelling of H⁺/K⁺‐ATPase was seen on the tubulovesicular membranes. When stimulated with histamine, the cultured parietal cells undergo morphological transformation, resulting in great expansion of apical membrane vacuoles. Immunogold labelling of H⁺/K⁺‐ATPase was present not only on the microvilli of expanded apical plasma membrane vacuoles but also in the electron‐dense coated pits. The present findings provide a clue to vesicular membrane trafficking in cultured gastric parietal cells, and assure the utility of the new procedure for high‐pressure freezing of primary culture cells.     

Improved visualization and quantitative analysis of fluorescent membrane sterol in polarized hepatic cells

Dehydroergosterol is a natural yeast sterol which has recently been employed for direct observation of intracellular sterol transport by UV microscopy. Here, methods are described for improved visualization and quantification of dehydroergosterol in the membranes of polarized HepG2 cells. Using a new online assay, it is shown that dehydroergosterol derived from a cyclodextrin complex inserted into the plasma membrane with a half time of t_1/2 ∼ 34 s. Based on a detailed bleaching analysis of dehydroergosterol, slightly different bleaching rates for dehydroergosterol in the basolateral and canalicular membrane were found, indicating different fluorophore environments. Bleaching correction in concert with 3D imaging allows for detection of dehydroergosterol enrichment in microvilli of the canalicular membrane forming the biliary canaliculus. Evidence is provided that some dehydroergosterol accumulating in a subapical compartment or apical recycling compartment can rapidly (t_1/2 ∼ 2 min) exchange in vesicles towards the biliary canaliculus while the majority of dehydroergosterol does not redistribute from this compartment. The rapidly exchanging pool resembles only a small portion of the total subapical compartment or apical recycling compartment-associated dehydroergosterol (about 15–30%). Kinetic modelling supports the theory that the subapical compartment or apical recycling compartment to biliary canaliculus transport pathway for sterol is unidirectional. This pathway might be important for rapid biliary transport of free sterol produced by hydrolysis of cholesteryl esters derived from high density lipoprotein.     

光子扫描隧道显微镜（PSTM）的研制与应用

本文对光子扫描隧道显微镜(PSTM)的发展背景、成像机理、当前国内外发展动态及其技术价值都作了较为深入的研究,并从经典几何光学和波动理论上对PSTM显微成像机理进行了探讨。此外,对解决假像问题和高精度分辨的突破提出了初步的看法。     

In situ oxidation and reduction of the oxides of cerium,praseodymium and terbium by high-voltage electron microscopy

In situ oxidation and reduction of the oxides of cerium, praseodymium and terbium in a controlled atmosphere and temperature have been studied utilizing a high-voltage electron microscope. Experiments were carried out in the environmental cell of the Berkeley KRATOS EM 1500 HVEM at temperatures between 298 K and 1023 K in an atmosphere of oxygen, hydrogen or vacuum. Electron diffraction patterns revealed the course of small fragments of the crystalline oxides. In nearly all cases, the degree of reduction recorded was greater than expected from equilibrium tensimetric studies in the absence of an electron beam. Furthermore, reoxidation appeared to be more sluggish and to a lesser extent than is observed in specimens outside the microscope.     

U-制造的概念、特性、主要优势和关键技术

随着物联网技术的飞速发展,以及制造企业精细化管理、实时化控制的需求,一种新兴的制造物联新模式——基于泛在计算的智能制造(U-制造)应运而生。对U-制造进行综合论述:回顾和总结国内外相关研究现状;给出U-制造的概念,通过与云制造、网络化制造等已有制造范式的比较,明确其主要特性;简要分析U-制造的主要优势;列举并阐述U-制造实际应用过程中涉及的若干关键技术。     

Synaptic connections of neurones identified by Golgi impregnation: Characterization by immunocytochemical,enzyme histochemical,and degeneration methods

For more than a century the Golgi method has been providing structural information about the organization of neuronal networks. Recent developments allow the extension of the method to the electron microscopic analysis of the afferent and efferent synaptic connections of identified, Golgi-impregnated neurones. The introduction of degeneration, autoradiographic, enzyme histochemical, and immunocytochemical methods for the characterization of Golgi-impregnated neurones and their pre-and postsynaptic partners makes it possible to establish the origin and also the chemical composition of pre-and postsynaptic elements. Furthermore, for a direct correlation of structure and function the synaptic interconnections between physiologically characterized, intracellularly HRP-filled neurones and Golgi-impregnated cells can be studied. It is thought that most of the neuronal communication takes place at the synaptic junction. In the enterprise of unravelling the circuits underlying the synaptic interactions, the Golgi technique continues to be a powerful tool of analysis.