Specimens For Electron Microscopy Research Articles

A study of dislocation transmission through a grain boundary in hcp Ti–6Al using micro-cantilevers

Micro-cantilevers with an equilateral triangular cross-section and an apex at the bottom were machined across grain boundaries in a Ti–6Al alloy sample using a focused ion beam (FIB). A nano-indenter was used to deform the micro-cantilevers. An <a> prism slip system was selectively activated in the upper grain by controlling the crystal orientation along the micro-cantilever. Specimens for transmission electron microscopy (TEM) were prepared from the deformed micro-cantilevers using dual-beam FIB. Bright field scanning transmission electron microscopy was used to investigate the process of slip propagation through the grain boundary.

Post-ion beam induced degradation of copper layers in transmission electron microscopy specimens

Copper containing transmission electron microscopy (TEM) specimens frequently show corrosion after focused ion beam (FIB) preparation. This paper reveals that the corrosion product is a Cu–S phase growing over the specimen surface. The layer is identified by energy-dispersive x-ray spectroscopy, and lattice spacing indexing of power spectra patterns. The corrosion process is further studied by TEM on cone-shaped specimens, which are intentionally stored after FIB preparation with S flakes for short time. Furthermore, a protective method against corrosion is developed by varying the time in the FIB vacuum and the duration of a subsequent plasma cleaning.

Post-thinning using Ar ion-milling system for transmission electron microscopy specimens prepared by focused ion beam system.

We investigate Ar ion-milling rates and Ga-ion induced damage on sample surfaces of Si and GaAs single crystals prepared by focused ion beam (FIB) method for transmission electron microscopy observation. The convergent beam electron diffraction technique with Bloch simulation is used to measure the thickness of the Ar-ion milled samples to calculate the milling rates of Si and GaAs single crystals. The measurement shows that an amorphous layer is formed on the sample surface and can be removed by further Ar-ion milling. In addition, the local symmetry breaking induced by FIB is investigated using quantitative symmetry measurement. The FIBed-GaAs sample shows local symmetry breaking after FIB milling, although the FIBed-Si sample has no considerable symmetry breaking.

Capsule-Based Processing and Handling of Electron Microscopy Specimens and Grids

It is a testament to the brilliance of the earliest biological electron microscopists that half a century later, most cell and tissue specimens for transmission electron microscopy (TEM) are still prepared using chemical fixation, polymer embedding, microtomy, and heavy-metal staining protocols based on those developed by Palade, Porter, Fullam, Claude, and others in the 1950s–1970s [1–5]. These methods remain in use today because they provide good fixation and electron contrast, and they enable thin sectioning. To perform these protocols, biological specimens are placed into vials filled with each chemical reagent, followed by manually exchanging reagents using transfer pipettes. Similarly, grids are stained by manually moving them between reagent droplets or dishes. However, why these fluid-handling methods have remained largely unchanged in the modern electron microscopy lab is surprising because fluid handing in life science laboratories was transformed during the same decades as TEM revolutionized biology. Two leading advancements in fluid handling were the introduction of the variable-volume pipetter by Gilson [6] in 1972 and the mass-produced micro-well plate (microtiter plate) invented by Cooke [7–8] and commercialized about 1966 [9].

Morphology of the oxyurid nematodes Trypanoxyuris (T.) cacajao n. sp. and T. (T.) ucayalii n. sp. from the red uakari monkey Cacajao calvus ucayalii in the Peruvian Amazon.

Cacajao calvus ucayalii (Thomas, 1928) (Primates: Pitheciidae), a subspecies endemic to the Peruvian Amazon, occurs in patchy and sometimes isolated populations in north-eastern Peru and is in a vulnerable situation, mainly due to habitat loss and hunting. This rareness and remote distribution means that, until now, parasitical studies have been limited. Based on optical and scanning electron microscopy of specimens of both sexes, we report two new species of Trypanoxyuris pinworms occurring in the large intestine of the Peruvian red uakari, namely Trypanoxyuris (Trypanoxyuris) cacajao and Trypanoxyuris (Trypanoxyuris) ucayalii. Both species showed a distinct morphology of the lips and cephalic structure. Sexual dimorphism in the lateral alae was observed in both male and the female worms, with ventral ornamentation being shown in the oesophageal teeth. The finding of these new pinworm species highlights the possibility of discovering other species.

Self-consistent method for quantifying indium content from X-ray spectra of thick compound semiconductor specimens in a transmission electron microscope.

Based on Monte Carlo simulations of X-ray generation by fast electrons we calculate curves of effective sensitivity factors for analytical transmission electron microscopy based energy-dispersive X-ray spectroscopy including absorption and fluorescence effects, as a function of Ga K/L ratio for different indium and gallium containing compound semiconductors. For the case of InGaN alloy thin films we show that experimental spectra can thus be quantified without the need to measure specimen thickness or density, yielding self-consistent values for quantification with Ga K and Ga L lines. The effect of uncertainties in the detector efficiency are also shown to be reduced.

X-Ray Transmission Characteristic Measurements of Polycapillary Optics Installed in an Analytical Electron Microscope

This paper studies the polycapillary optics that are used to focus and transmit the X-rays emitted by a transmission electron microscope (TEM) specimen to an energy dispersive spectrometer using a superconducting transition edge sensor (TES) microcalorimeter. In this study, X-rays are collected from a TEM specimen and are then focused on a silicon drift detector, from which energy spectrum measurements of the polycapillary optics are taken and used to determine the transmission characteristics of the optics. When the polycapillary optics are used, an increase of 25.9 is seen in the intensity of 4.6 keV X-rays, while an increase of 6.0 is seen for 12.6 keV X-rays. The focal spot sizes of the X-ray beams from the polycapillary optics are found to be 382 μm for the 4.6 keV X-rays and 156 μm for the 12.6 keV X-rays. Further improvement of these characteristics can be achieved by improving the alignment of the optics to the detector and the collimator, which immediately precedes the detector, and by optimizing the collimator width.

Investigation of Ar Ion-Milling Rates for Transmission Electron Microscopy Specimens

Journal Article Investigation of Ar Ion-Milling Rates for Transmission Electron Microscopy Specimens Get access Min-Hee Lee, Min-Hee Lee Advanced Process and Materials R&BD Group, Incheon Regional Division, Korea Institute of Industrial Technology, Incheon 406-840, Republic of Korea Search for other works by this author on: Oxford Academic Google Scholar Kyou-Hyun Kim Kyou-Hyun Kim Advanced Process and Materials R&BD Group, Incheon Regional Division, Korea Institute of Industrial Technology, Incheon 406-840, Republic of Korea Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 21, Issue S3, 1 August 2015, Pages 1981–1982, https://doi.org/10.1017/S1431927615010685 Published: 23 September 2015

Combining 2 nm Spatial Resolution and 0.02% Precision for Deformation Mapping of Semiconductor Specimens in a Transmission Electron Microscope by Precession Electron Diffraction.

Precession electron diffraction has been used to provide accurate deformation maps of a device structure showing that this technique can provide a spatial resolution of better than 2 nm and a precision of better than 0.02%. The deformation maps have been fitted to simulations that account for thin specimen relaxation. By combining the experimental deformation maps and simulations, we have been able to separate the effects of the stressor and recessed sources and drains and show that the Si3N4 stressor increases the in-plane deformation in the silicon channel from 0.92 to 1.52 ± 0.02%. In addition, the stress in the deposited Si3N4 film has been calculated from the simulations, which is an important parameter for device design.

Synthesis and characterization of Fe–Ni/ɣ-Al2O3 egg-shell catalyst for H2 generation by ammonia decomposition

The Fe–Ni alloyed nanoparticles are a promising alternative to expensive ruthenium-based catalysts for a real-scale application of hydrogen generation by ammonia decomposition. In practical applications, millimeter-sized extrudates are used as catalyst supports, where the spatial distribution of the active phase should match with the type of reaction. In this work, a novel synthesis route was developed for the preparation of a Fe–Ni/ɣ-Al2O3 egg-shell catalyst. Egg-shell is a preferred profile considering the highly endothermic nature of ammonia decomposition reaction. The high viscosity of glycerol, used as a solvent during impregnation, prevents the fast migration of the Fe–Ni active phase solution toward the inner-core of ɣ-Al2O3, giving control over the large capillary pressures. The distribution profiles were analyzed at macroscopic scale through scanning electron microscopy mapping (SEM-EDX) and optical microscopy. A three-dimensional (3-D) reconstruction of the spherical-shaped ɣ-Al2O3 was achieved using X-ray micro tomography and the Fe–Ni egg-shell spatial distribution was inspected throughout the entire volume of the support body. Transmission electron microscopy (TEM) specimen preparation using focused ion bean (FIB) milling allowed to acquire high resolution images of the Ni and Fe nanoparticles on ɣ-Al2O3, which is particularly challenging due to the crystalline nature of this support. Distinct regions of the egg-shell catalyst were analyzed through scanning TEM (STEM) and TEM. The outer-shell region showed the presence of Fe and Ni alloyed nanoparticles with a size of approximately 5nm.. The egg-shell catalyst showed significant higher activity in ammonia decomposition by converting 3 times more ammonia to equilibrium conversion than either egg-white or catalyst with uniform distribution. Moreover, the egg-shell catalyst conversion only dropped 0.05% after 10h of reaction, for a space velocity of 475mlmin−1g−1.

Measurement and analysis of fatigue crack deformation on the macro- and micro-scale

The paper describes an experiment which performs in-situ loading of a small compact tension specimen in a scanning electron microscope. Images are collected throughout a number of successive loadincg cycles. These are then analysed using digital image correlation (DIC) in order to produce crack flank displacements as a function of load. This data is then compared with a simple elastic approach, and it is concluded that elastic-plastic analysis is required in order to accurately capture the displacements close to the crack tip. A simple approach due to Pommier and Hamam is therefore employed. This gives a better representation of the data, but predicts a variation of crack tip displacement, ?, which is difficult to explain from a physical perspective. The need for a more sophisticated analysis of the data is therefore highlighted.

Secondary signal imaging (SSI) electron tomography (SSI-ET): A new three-dimensional metrology for mesoscale specimens in transmission electron microscope

We have demonstrated a new electron tomography technique utilizing the secondary signals (secondary electrons and backscattered electrons) for ultra thick (a few μm) specimens. The Monte Carlo electron scattering simulations reveal that the amount of backscattered electrons generated by 200 and 300keV incident electrons is a monotonic function of the sample thickness and this causes the thickness contrast satisfying the projection requirement for the tomographic reconstruction. Additional contribution of the secondary electrons emitted from the edges of the specimens enhances the visibility of the surface features. The acquired SSI tilt series of the specimen having mesoscopic dimensions are successfully reconstructed verifying that this new technique, so called the secondary signal imaging electron tomography (SSI-ET), can directly be utilized for 3D structural analysis of mesoscale structures.

Using transmission Kikuchi diffraction to study intergranular stress corrosion cracking in type 316 stainless steels

Transmission Kikuchi diffraction (TKD), also known as transmission-electron backscatter diffraction (t-EBSD) is a novel method for orientation mapping of electron transparent transmission electron microscopy specimen in the scanning electron microscope and has been utilized for stress corrosion cracking characterization of type 316 stainless steels. The main advantage of TKD is a significantly higher spatial resolution compared to the conventional EBSD due to the smaller interaction volume of the incident beam with the specimen.Two 316 stainless steel specimen, tested for stress corrosion cracking in hydrogenated and oxygenated pressurized water reactor chemistry, were characterized via TKD. The results include inverse pole figure (IPFZ) maps, image quality maps and misorientation maps, all acquired in very short time (<60min) and with remarkable spatial resolution (up to 5nm step size possible). They have been used in order to determine the location of the open crack with respect to the grain boundary, deformation bands, twinning and slip. Furthermore, TKD has been used to measure the grain boundary misorientation and establish a gauge for quantifying plastic deformation at the crack tip and other regions in the surrounding matrix. Both grain boundary migration and slip transfer have been detected as well.

Preparation of micro-foils for TEM/STEM analysis from metallic powders

A technique has been developed which facilitates the preparation of electro-polished micro-foil transmission electron microscopy (TEM) specimens, which have previously been machined out of ≈100μm diameter metallic powder particles using a Focussed Ion Beam (FIB) instrument. The technique can be used to create small volume TEM specimens from most metallic powder particles and bulk metal samples. This is especially useful when the matrices are ferritic steels, which are often difficult to image in the electron microscope, since the necessary aberration corrections change as the sample is tilted in the magnetic field of the objective lens.Small samples, such as powder particles, were attached to gold support grids using deposited platinum and were then ion milled to approximately 2μm thickness in a focussed ion beam (FIB) instrument. Subsequently, the specimen assemblies were electropolished for short durations under standard conditions, to produce large (5μm×5μm) electron transparent regions of material. The specimens produced by this technique were free from FIB related artefacts and facilitated atomic resolution scanning-TEM (STEM) imaging of ferritic and nickel matrices containing, for example, yttrium rich oxide nano-dispersoids.

Analysis of blood cell autophagy distribution in hematologic diseases by transmission electron microscope

目的研究血细胞自噬在血液病中的分布特征及其可能病理机制。方法回顾性分析3 277例血液病患者电镜标本，利用透射电子显微镜观察血细胞自噬现象，分析血细胞自噬在血液病中的分布特点，结合临床检测和诊断结果分析其病理机制。结果检出15例患者伴有成熟粒细胞或有核红细胞自噬现象，其中骨髓增生异常综合征6例，急性白血病2例，再生障碍性贫血、纯红细胞再生障碍性贫血、地中海贫血、缺铁性贫血、淋巴瘤、多发性骨髓瘤和真性红细胞增多症各1例。15例患者中粒细胞自噬11例，有核红细胞自噬4例。9例伴细胞凋亡，6例伴细胞溶解，5例伴细胞巨幼样变。结论血液病成熟粒细胞和有核红细胞自噬多见于骨髓增生异常综合征，细胞凋亡、巨幼样变和溶解等病态造血可能诱发细胞自噬。

Nanoscale bonding between human bone and titanium surfaces: osseohybridization.

Until now, the chemical bonding between titanium and bone has been examined only through a few mechanical detachment tests. Therefore, in this study, a sandblasted and acid-etched titanium mini-implant was removed from a human patient after 2 months of placement in order to identify the chemical integration mechanism for nanoscale osseointegration of titanium implants. To prepare a transmission electron microscopy (TEM) specimen, the natural state was preserved as much as possible by cryofixation and scanning electron microscope/focused ion beam (SEM-FIB) milling without any chemical treatment. High-resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS), and scanning TEM (STEM)/electron energy loss spectroscopic analysis (EELS) were used to investigate the chemical composition and structure at the interface between the titanium and bone tissue. HRTEM and EDS data showed evidence of crystalline hydroxyapatite and intermixing of bone with the oxide layer of the implant. The STEM/EELS experiment provided particularly interesting results: carbon existed in polysaccharides, calcium and phosphorus existed as tricalcium phosphate (TCP), and titanium existed as oxidized titanium. In addition, the oxygen energy loss near edge structures (ELNESs) showed a possibility of the presence of CaTiO3. These STEM/EELS results can be explained by structures either with or without a chemical reaction layer. The possible existence of the osseohybridization area and the form of the carbon suggest that reconsideration of the standard definition of osseointegration is necessary.

Transmission Electron Microscopy Specimen Preparation for Layer-area Graphene by a Direct Transfer Method

Graphene is a monolayer of carbon atoms arranged in a honeycomb lattice and is a basic building block for graphitic materials of all other dimensionalities. It can be wrapped up into zero-dimensional fullerenes, rolled into one-dimensional nanotubes or stacked into three-dimensional graphite. Graphene has unusual electrical, mechanical, and thermal properties, so it presents new opportunities in fundamental research and practical applications (Zhang et al., 2005; Geim & Novoselov, 2007; Geim, 2009). Recently, large-area synthesis methods for graphene have been advanced epitaxial growth on SiC (Brar et al., 2007; Qi et al., 2010) and chemical vapor deposition on metal substrates such as Ni (Dedkov et al., 2008) and Cu (Li et al., 2009). Particularly, Cu is a considerably attractive substrate because it can be produce layer-area graphene. Transmission electron microscopy (TEM) is a direct and re latively fast imaging tool ideally suited for suspended atomically thin membranes, so it has been successfully applied to study adsorbates on graphene and the atomic structure of graphene (Huang et al., 2011). To observe graphene by TEM, the graphene must transfer from metallic Cu substrates to a TEM grid. Standard transfer of layer graphene has been carried out using a polymer coating such as polymethyl methacrylate (PMMA) or polydimethylsiloxane as a temporary support during etching of the metal substrate to prevent tearing of the graphene (Reina et al., 2009). However, the standard transfer method using these polymers can contaminate and mechanically damage the graphene because it includes several wet chemical steps. Thus, a simple and gentle method is necessary for good TEM images of graphene. Direct transfer method doesn’t include polymer coating process. So it is expected simple and effective method to make graphene specimen by avoiding wet chemical steps (Regan, 2010).

Detection of abnormal extracellular matrix in the interstitium of regenerating renal tubules.

Stem/progenitor cells are promising candidates for the regeneration of parenchyma in acute and chronic renal failure. However, recent data exhibit that survival of stem/progenitor cells after implantation in diseased renal parenchyma is restricted. To elaborate basic parameters improving survival, cell seeding was simulated under advanced in vitro conditions. After isolation, renal stem/progenitor cells were mounted in a polyester interstitium for perfusion culture. During generation of tubules, chemically defined CO2 Independent Medium or Leibovitz’s L-15 Medium was applied. Specimens were then fixed for transmission electron microscopy to analyze morphological features in generated tubules. Fixation in conventional glutaraldehyde (GA) solution shows development of tubules each exhibiting a polarized epithelium, an intact basal lamina and an inconspicuous interstitium. In contrast, special fixation of specimens in GA solution containing cupromeronic blue, ruthenium red or tannic acid unveils previously not visible extracellular matrix. Control experiments elucidate that a comparable extracellular matrix is not present in the interstitium of the matured kidney. Thus, generation of renal tubules in combination with advanced fixation of specimens for electron microscopy demonstrates that development of abnormal features in the newly developed interstitium has to be considered, when repair of renal parenchyma is performed by implantation of stem/progenitor cells.

Characterization of V-shaped Defects in 4H-SiC Homoepitaxial Layers

Synchrotron white beam x-ray topography images show that faint needle-like surface morphological features observed on the Si-face of 4H-SiC homoepitaxial layers using Nomarski optical microscopy are associated with V-shaped stacking faults in the epilayer. KOH etching of the V-shaped defects reveals small oval pits connected by a shallow trench which correspond to the surface intersections of two partial dislocations and the stacking fault connecting them. Transmission electron microscopy (TEM) specimens from regions containing the V-shaped defects prepared using focused ion beam milling show stacking sequences of (85), (50) and (63) at the faulted region using high resolution TEM. In order to study the formation mechanism of the V-shaped defects, low dislocation density 4H-SiC substrates were chosen for epitaxial growth, and the corresponding regions before and after epitaxy growth are compared in SWBXT images. It is found that no defects in the substrate are directly associated with the formation of the V-shaped defects. Simulation results of the contrast from the two partial dislocations associated with V-shaped defects in synchrotron monochromatic beam x-ray topography reveals the opposite sign nature of their Burgers vectors. Therefore, a mechanism of 2D nucleation during epitaxy growth is postulated for the formation of the V-shaped defects, which requires elimination of non-sequential c/4[0001] bilayers from the original structure to create the observed faulted stacking sequence.

Morphological Comparison of the Filiform Papillae of New Zealand White Rabbits (Oryctolagus cuniculus) as Domestic Mammals and Egyptian Fruit Bat (Rousettus aegyptiacus) as Wild Mammals Using Scanning Electron Microscopic Specimens

Se comparo la estructura morfologica de las papilas filiformes de un mamifero domestico (conejo neozelandes) y de un mamifero silvestre (murcielagos de la fruta egipcio). El estudio fue realizado en animales de ambos sexos. Se observo cuatro tipos de papilas linguales, en ambas especies de animales. En los murcielagos de la fruta egipcio se observaron seis subtipos de papilas filiformes; tres en la parte anterior (pequeno, conico y gigante), dos en la parte media (aciano y hojas como papilas) mientras que en la parte posterior se observaron papilas filiformes y papilas de transicion conica. En los conejos se observaron cuatro subtipos de papilas filiformes; conica cucharada (en la parte anterior lingual), procesado (en el margen anterior de la prominencia lingual), tipo hoja (en la zona posterior de la prominencia lingual) y papilas filiformes triangulares (en la raiz lingual). La forma, tamano, numero y orientacion de las papilas linguales y sus procesos varian de acuerdo a la funcion y a la ubicacion en la lengua (especificos de la region) en relacion con los habitos de alimentacion, las estrategias para la obtencion de alimentos, las condiciones climaticas y tipos de particulas de alimentos.