bluuebunny/crossref_metadata_2025 huggingface dataset:
A Commentary on Recent Developments in X-RAY Detectors and Ancillary Instrumentation and Data Extraction Algorithms
Authors: Fiori Charles E. , Swyt Carol R.
Published: June 2020

When a lithium-drifted silicon, Si(Li), energy dispersive X-ray detector is attached to a scanning electron microscope or a scanning transmission electron microscope, it becomes possible to perform an assay of the elemental composition of a localized region of a specimen. This capability has existed now for almost 20 years. During this time, the quality of the analytical results has slowly improved with the availability of better instrumentation and increased understanding of the physical basis of measurement and matrix effects. During the last few years, the pace in both instrumental development and theoretical understanding has picked up dramatically. What seemed like a maturing and ever more mundane field has now been reinvigorated. We will catalog here and comment on several of the developments which have occurred in x-ray detectors and in the hardware and software used to process the resulting x-ray signals into quantitative information.

Although the Si(Li) x-ray spectrometer has dominated the field of x-ray microanalysis for many years, recent developments in intrinsic germanium (IG) detectors have produced spectrometers which, in several important characteristics, rival or exceed those of the Si(Li) spectrometer.
Novel Dry Dispersions for Automated Scanning Electron Microscopy: Energy and Wavelength Dispersive X-RAY Spectrometry (ASEM-EDS/WDS)
Authors: Detter-Hoskin Lisa D. , Wortman Beth G.
Published: June 2020

In recent years, the need for more precise size and chemical analysis of materials has been stressed since these features can have major effects on product performance. Historically, optical and manual scanning electron microscopy, the latter in combination with energy and wavelength dispersive x-ray spectrometry (SEM-EDS/WDS), have been used in our laboratory to size and identify the chemical composition of materials. In recent years, automated SEM-EDS/VDS methods have been developed and are likewise used for similar measurements, especially where large sets of particle information are desired.

The inherent success of ASEM-EDS/WDS critically depends on sample preparation. Particle dispersion criteria include: 1) a smooth substrate, free of defects, 2) a uniform distribution of particles, and 3) proper density of particle loading. Traditionally, particles have been suspended and homogenized in liquid media and then either filtered through membrane filters or aliquots directly dispersed onto highly polished carbon planchets. While wet dispersions are applicable to a wide array of materials, in the case of complex materials, alternative dry dispersion protocols are necessary.
Structure Change of Crystalline Graphite Due to Hydrogen Ion Irradiation Observed by In-Situ Electron Energy Loss Spectroscopy
Authors: Kushita Kouhei , Hojou Kiichi
Published: June 2020

Carbon materials such as isotropic graphite and C/C composite are widely used for first walls or divertor plates in fusion reactors such as JT-60. In this respect, as well as from fundamental viewpoints, observations of microstructural change in ion-irradiated graphite is important. Although radiation damage in carbon materials has widely been studied, there are few data in this field examined by Electron Energy Loss Spectroscopy. The present paper reports the results of in-situ EELS observation of ion-irradiated crystalline graphite.

Specimens used in this experiment were pseudo-monocrystal graphite supplied from Le Carbone Lorraine. Thin films of the graphite suitable for transmission electron microscopy were made by crashing a small portion of the sample in a mortar with npropyl alcohol. The resultant flake-like thin films were scooped up with a micro mesh, and then irradiated with 10 keV ions at an ambient temperature with a flux of 6.3×1013H/cm2s. The apparatus schematically shown in Fig.1 was used for the ion irradiation as well as for electron microscopy and electron energy loss spectroscopy.
Ionic homeostasis and subcellular element compartmentation
Authors: LeFurgey Ann , Ingram Peter , Blum J.J. , Carney M.C. , Hawkey L.A. , Kronauge J.F. , Lieberman Melvyn , Mandel L.J. , Piwnica-Worms D.R. , Sommer J.R. , Spencer A.J.
Published: June 2020

Subcellular compartments commonly identified and analyzed by high resolution electron probe x-ray microanalysis (EPXMA) include mitochondria, cytoplasm and endoplasmic or sarcoplasmic reticulum. These organelles and cell regions are of primary importance in regulation of cell ionic homeostasis. Correlative structural-functional studies, based on the static probe method of EPXMA combined with biochemical and electrophysiological techniques, have focused on the role of these organelles, for example, in maintaining cell calcium homeostasis or in control of excitation-contraction coupling. New methods of real time quantitative x-ray imaging permit simultaneous examination of multiple cell compartments, especially those areas for which both membrane transport properties and element content are less well defined, e.g. nuclei including euchromatin and heterochromatin, lysosomes, mucous granules, storage vacuoles, microvilli. Investigations currently in progress have examined the role of Zn-containing polyphosphate vacuoles in the metabolism of Leishmania major, the distribution of Na, K, S and other elements during anoxia in kidney cell nuclel and lysosomes; the content and distribution of S and Ca in mucous granules of cystic fibrosis (CF) nasal epithelia; the uptake of cationic probes by mltochondria in cultured heart ceils; and the junctional sarcoplasmic retlculum (JSR) in frog skeletal muscle.
High-efficiency x-ray monochromator for measurement of Ca in the TEM
Authors: Sun Songquan , Tormey John McD. , Wittry David B.
Published: June 2020

A novel miniature wavelength dispersive (WDS) monochromator with a LiF crystal has been developed for use in a transmission electron microscope (JEOL 100CX). Our goal has been to improve on the limited sensitivity available when energy dispersive spectrometry (EDS) is used to measure low concentrations of Ca in biological tissues. This paper presents the calculated performance, design features and experimental results .

Limitations of EDS - When EDS is used to measure biological Ca in an electron column instrument, precision is severely limited by counting statistics. In the past, EDS was used by Tormey to quantify Ca in cardiac muscle, employing procedures similar to those used by Shuman and Somlyo. In a typical application, myofibrillar [Ca] increased from 1.4 ± 0.2 to 2.6 ± 0.3 mmol/kg dry wt when going from rest to contracture. This precision (± standard error of mean) was the result of 125 measurements in each condition.
Low-cost system for electron probe microanalysis based on a personal computer
Authors: Foster Margaret C. , Saubermann Albert J.
Published: June 2020

The development of personal computers increases the options available for electron probe microanalysis. Hardware and software are now available for personal computers which make it feasible to use them to acquire, process, and analyze x-ray spectra. One advantage of a personal computer (PC) based system is the low cost--approximately 20% of the cost of other options. A second advantage is that a system can be developed which is tailored to the needs of the laboratory, so that experimental questions asked of the data can dictate procedures for data acquisition and processing.

We have developed a PC-based system for electron probe microanalysis, which we use for data acquisition, processing, and analysis of frozen and freeze-dried biological samples. X-ray spectra may be acquired either for spot analysis or for elemental images. Spectra acquired from large areas of the frozen, hydrated sample are used together with spectra from the freeze-dried specimen to calculate concentrations relative to sample wet weight.
Atrial specific granules: The intracellular calcium store
Authors: Zhong Cisheng , Yu Zhang , Yu Wenqian , Ling Yiping
Published: June 2020

It is well known that certain organells in cytosol contain high calcium concentration and they are named intracellular Ca stores. These stores regulate the intracellular Ca concentration. The present project aims at exploring whether the release of atrial natriuretic peptide (ANP) from the atrial specific granules(ASG) is dependent on the release of calcium from the ASG. For this purpose, we have to know first whether the ASG contain high Ca concentration. In this work, positive results were obtained by quantitative electron probe x ray microanalysis (EPMA) and Ca-ATPase cytochemical localization.

Adult female Sprague Dawley rats were used. The auricle samples were prepared in five different procedures: 1 )preparation of routine ultrathin sections; 2)ethanolic phosphotungstic acid(EPTA) staining ultrathin sections for ASG showing; [1] 3) cytochemical localization of Ca-ATPase ;[2] 4) preparation of ultrathin cryosections of fresh rapid frozen auricles; [3] 5) quantitative EPMA with Link AN10000 and Link Quantem/FLS quantitative analysis software.
Electron-probe x-ray microanalysis studies on the intracellular calcium translocation during the contraction-relaxation cycle in the fish swimbladder muscle
Authors: Suzuki Suechika , Hino Naoki , Sugi Haruo
Published: June 2020

The swimbladder muscle of a teleost fish,Sebasticus marmoratus, contracts rapidly to produce sounds for communication and contains extremely well developed sarcoplasmic reticulum (SR), providing a material suitable for studying the intracellular Ca translocation during the contraction-relaxation cycle. We examined the change of Ca distribution along the sarcomere at various states of the fibers during the contractionrelaxation cycle in the swimbladder muscle by means of quantitative electron probe X-ray microanalysis of cryosections.

The muscle fibers were rapidly frozen at rest, during sustained contraction and at 0.1 and 1.0 sec after the onset of relaxation with a dual-jet liquid propane freezing device. Cryosections (200 nm thick) were cut from the middle portion of the frozen fibers at -110°C on a LKB NOVA cryoultramicrotome, and placed on thin carbon supporting films on Nigrids. Then the cryosections were freeze-dried at 10-6torr and below -80°C. Electron probe X-ray microanalysis was performed on a liquid N2-cooled Be-stage at -130°C in a JEOL 2000FX electron microscope operated at 80 kV and equipped with a Tracor Northern TN5500 energy dispersive X-ray microanalyzer.
Spectroscopy imaging of involvement of sugar residues in adhesion step and interiorization of T. Cruzi heart muscle cells by lectin binding
Authors: Santos Barbosa Helene , Goldenberg Samuel , de Nazareth Mariä , Meirelles L.
Published: June 2020

The high percentage of adhesion and interiorization of metacyclic trypomastigotes (clone Dm28c) of T. cruzi obtained from TAU3AAG differentiation medium (1) to heart muscle cells (HMC) points out this system as a very suitable to study the involvment of membrane components during the recognition and endocytosis process leading to formation of endocytic vacuole (2).

In this report, we used the lectin Ricinus communis (RCA I) and Triticum vulgaris (WGA) as markers of galactosyl and N-acetyl-D-glucosamine or N-acetyl-neuraminic acid residues, respectivily, from host cell for studies of involvment in the attachment and interiorization of parasite. In order to investigate the localization of these sugars residues on the surface of HMC, we incubated the cells in the presence of RCA conjugated with ferritin (50 μg/ml) and WGA with gold particles at 42C for 30 min. The cell cultures were washed, infected T. cruzi, for 2-4 hours, fixed and processed for TEM.
Cryogenic cooling and in situ analysis of fluid inclusions in geological materials with an ultra-thin windowed Si(Li) detector in a SEM
Authors: Griffin Brendon
Published: June 2020

The determination of fluid compositions in geological processes is an essential but difficult problem. Many techniques have been developed based on the optical microscope. These are indirect analytical techniques, determining fluid composition by analogy. More sophisticated spectroscopic techniques, e.g. laser microprobes, are relatively inaccessible through high capital cost. Scanning electron microscopes [SEM’s] and electron microprobes have been used to identify the non-volatile components by decrepitating near-surface inclusions with an energetic electron beam and then analysing the residual.

It is found that application of the cryo-SEM to the study of fluid inclusions with the common availability of windowless and low absorbance windowed Si(Li) detectors is a convenient and low cost technique. Suitable slabs (<1 mm) are frozen and then fractured. No coating is applied, to minimise element interference. The fresh surfaces are inspected using backscattered electron [BSE] imaging and exposed inclusions analysed.

Studies of inclusions in quartz, fluorite and sphalerite have determined the presence of carbon dioxide, water and various daughter salts, including halite (NaCl) and hydrophilite (CaCl2).
Electron probe microanalysis of borophosphosilicate coatings
Authors: Willich Peter , Schiffmann Kirsten
Published: June 2020

Planarization and passivation of integrated circuits by use of borophosphosilicate glass (BPSG) is of considerable technological interest. BPSG is prepared by chemical vapour deposition and electron probe microanalysis (EPMA) offers the possibility of non-destructive characterization in respect of composition and film thickness. Particular difficulties of EPMA are due to the insulating character of BPSG in combination with the demand for analysis of ultra-light elements (B and O). However, EPMA of BPSG also demonstrates the accuracy of recent bulk and thin film data processing when based on refined experimental procedures.

Carbon coating is required to carry out reproducible measurements on BPSG. The C-Kα intensity determined on various samples and mineral standards (Table 1) shows a wide variation of the carbon film thickness (10-40 nm), even when a set of samples was simultaneously coated. The film thickness of BPSG is in the range of 0.3-1.5 μm and consequently EPMA has to be performed at a low electron energy (Eo= 4-10 keV) to enable ‘bulk’ quantitative analysis without influence of the silicon substrate.
Application Of Electron Probe Analyses Of Minerals In Discussing The Relationship Between Ductile Deformation And Metamorphism
Authors: Guochuan Fan , Zhongshi Sun
Published: June 2020

Under influence of ductile shear deformation, granulite facies mineral paragenesis underwent metamorphism and changes in chemical composition. The present paper discusses some changes in chemical composition of garnet in hypers thene_absent felsic gnesiss and of hypersthene in rock in early and late granulite facies undergone increasing ductile shear deformation .

In garnet fetsic geniss, band structures were formed because of partial melting and resulted in zoning from massive⟶transitional⟶melanocrate zones in increasing deformed sequence. The electron-probe analyses for garnet in these zones are listed in table 1 . The Table shows that Mno, Cao contents in garnet decrease swiftly from slightly to intensely deformed zones.In slightly and moderately deformed zones, Mgo contents keep unchanged and Feo is slightly lower. In intensely deformed zone, Mgo contents increase, indicating a higher temperature. This is in accord with the general rule that Mgo contents in garnet increase with rising temperature.
Microanalyses Of Structural Defects In Polymer-Derived Ceramic Fibers
Authors: Freeman H. A. , Rabe J. A.
Published: June 2020

Microanalyses were performed with a Cameca MBX scanning electron microprobe and a JEM 2000FX analytical electron microscope to determine the composition of foreign defect structures found on primary fracture surfaces of ceramic fibers derived from melt-spun Si-N-C-O polymeric precursors. The defects were the critical flaws responsible for deterioration of tensile strength in these fibers after thermal exposure in the range of 1400°C and above. High fiber strength is necessary to provide reinforcement and toughening in structural ceramic composites during high temperature use.

Among the defects found were roughly spherical internal nodular flaws which contained Pb (Fig. 1) as well as others (Fig. 2) containing both Pb and Sn. Granular aggregates were also seen in which Fe and Cr were detected. Other nodular surface defects contained Ca, minor Al, and levels of 0 higher than that in the surrounding fiber (Fig. 3) . Extremely fine whisker growths at discrete sites along the length of some fibers were identified as silicon oxynitride by electron diffraction.
In Situ Ion Beam Cleaning in a Cambridge S-200 SEM
Authors: Laabs F.C.
Published: June 2020

The increased use of the scanning electron microscope as a flexible analytical tool has resulted in applying its use to a variety of problems which utilize signals that originate or are controlled by surface properties, including crystallographic orientation, contamination and structural deformation of the surface layer. This paper describes results and observations of efforts to control and remove that layer by energetic argon ion bombardment.

Experimental
A Kratos Mini-Beam I ion gun was attached to a Cambridge Model S-200 scanning electron microscope utilizing the horizontal port normally occupied by an energy dispersive spectrometer (Figure 1). The EDS spectrometer was moved to a position 35 degrees above the port position. This configuration results in the ion gun lying in a plane perpendicular to the electron beam and 45 degrees to the tilt axis, necessitating tilting the sample toward the ion beam during ion bombardment and, importantly, sputtered material is directed away from the EDS detector.
Recent Advances In The Analysis And Interpretation Of C-O-H-N Fluids By Application Of Laser Raman Microspectroscopy
Authors: Dill Pasteris Jill , Seitz Jeffery C. , Wopenka Brigitte , Chou I-Ming
Published: June 2020

One of the major goals of a geologist is to infer, from his field and laboratory observations, the temperature, pressure, and compositional parameters of the ambient system during rock formation or ore deposition. Because fluids are actively involved in many rock-forming processes, fluid inclusions trapped within minerals are studied as evidence of the pertinent system parameters. Individual minerals may contain several generations of fluid inclusions due to the complex histories of many geological environments. Micro-analytical techniques for the measurement of small quantities of materials in individual inclusions on the order of a few micrometers in diameter therefore are required.

The classical technique is microthermometry, which involves monitoring phase changes in an inclusion during controlled cooling and heating on a microscope stage. Given appropriate phase diagrams (not available in many cases) for the chemical system under study, the phase changes at recorded temperatures can be interpreted in terms of a specific fluid composition and density.
Interlaboratory study of the accuracy of airborne asbestos analysis by TEM
Authors: Turner S. , Steel E.B. , Beard M.E.
Published: June 2020

The determination of the concentration of asbestos in air or water is a goal common to research laboratories conducting environmental and health related studies and to commercial laboratories involved in asbestos abatement projects. The analytical procedure is a multistep process in which 1) particles from a known volume of air or water are deposited onto the surface and/or interior of a filtering media, 2) the particles are transferred to a carbon film suitable for TEM analysis and 3) a known area of the carbon film is systematically traversed and particles of interest identified by use of the TEM. In this work, an interlaboratory study was conducted to determine the accuracy and problems encountered by operators performing the electron microscope analysis.

Chrysotile and nonasbestos particles were deposited onto a 37 mm polycarbonate filter from a freon-based solution. Grid sections suitable for electron microscope analysis were prepared from the filter and sent to eighteen commercial laboratories.
Fluidized Catalytic Cracking Catalyst Microstructure as Determined by A Scanning Ion Microprobe
Authors: Lampert J.K. , Koermer G.S. , Macaoy J.M. , Chabala J.M. , Levi-Setti R.
Published: June 2020

We have used high spatial resolution imaging secondary ion mass spectrometry (SIMS) to differentiate mineralogical phases and to investigate chemical segregations in fluidized catalytic cracking (FCC) catalyst particles. The oil industry relies on heterogeneous catalysis using these catalysts to convert heavy hydrocarbon fractions into high quality gasoline and fuel oil components. Catalyst performance is strongly influenced by catalyst microstructure and composition, with different chemical reactions occurring at specific types of sites within the particle. The zeolitic portions of the particle, where the majority of the oil conversion occurs, can be clearly distinguished from the surrounding silica-alumina matrix in analytical SIMS images.

The University of Chicago scanning ion microprobe (SIM) employed in this study has been described previously. For these analyses, the instrument was operated with a 40 keV, 10 pA Ga+ primary ion probe focused to a 30 nm FWHM spot. Elemental SIMS maps were obtained from 10×10 μm2 areas in times not exceeding 524s.
Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)
Authors: Schueler Bruno , Odom Robert W.
Published: June 2020

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.

This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.
X-ray Microanalysis of Fractured Bulk Frozen Hydrated Samples
Authors: Echlin Patrick
Published: June 2020

While it is generally accepted that low temperature techniques offer the best approach for the analysis of diffusible substances in biological materials, there are still uncertainties concerning the optimal, total experimental approach. There are two types of sample and two preparative options; bulk samples or sections in either the frozen hydrated or frozen dried state. A combination of any one sample and procedure will provide an experimental approach which although giving analytical information about the sample, does so with varying degrees of spatial resolution and quantitative accuracy, absolute and relative detection limits, and preservation of the natural distribution of the substances concerned. The advantages and disadvantages of analysing sections or bulk material have been sufficiently well rehearsed in the literature that they do not need repeating here. Similarly, the problems associated with the analysis of frozen hydrated material are now generally recognized if not completely understood. This communication will focus on the perceived advantages of using fractured, frozen hydrated bulk material as a preparative procedure to measure local elemental concentrations of whole cells, tissues and intercellular spaces with particular emphasis on the analysis of mature vacuolate plant material.
The Connective Tissue Matrix of Cartilage as Revealed by Standard Fixation, Ruthenium Staining, High-Pressure Freezing, and Embedding in Water Soluble Media: A Comparison of Methods
Authors: Keene Douglas R.
Published: June 2020

Proteoglycan is a major component of the cartilage extracellular matrix, and the overall structure of this anionic molecule is highly dependent on the hydrated environment of cartilage. Without specific stabilization, proteoglycans are extracted or collapsed during deydration while processing for electron microscopy. The purpose of these experiments is to determine a method by which the structure of proteoglycans might be stabilized for electron microscopic evaluation.

Chick sternal cartilage was prepared for transmission electron microscopy by the following methods and the resultant tissue ultrastructure compared: A) 1.5/1.5% gluteraldehyde/paraformaldehyde and 1% OsO4 fixation, dehydration in ethanol, propylene oxide, and embedding in Spurrs epoxy B) Fixation as in (A) directly followed by infiltration and embedding in Hexamethylol-melamine-methyl-ether (a water soluble embedding medium) trade name “nanoplast” C) Fixation by high pressure freezing followed by freeze substitution in acetone/OsO4 prior to embedding in epon 812. In variations of methods A and B above, ruthenium red (RR, 1500 ppm) or ruthenium hexamine trichloride (RHT, 6000 ppm) were added to the primary and secondary fixatives. All tissue sections were stained in uranyl acetate and lead citrate.
The Contributions Of Analytical Electron Microscopy to the Detection and Quantification of Asbestos in Human Lung Samples
Authors: Roggli Victor L.
Published: June 2020

Analytical electron microscopy has contributed a great deal to our understanding of asbestosrelated diseases. Exposure to the various forms of asbestos, which include the serpentine form known as chrysotile asbestos, and the amphibole forms referred to as amosite, crocidolite, tremolite, anthophyllite, and actinolite asbestos, has been associated with the development of a number of diseases in man. These include asbestosis (scarring of the lung parenchyma), pleural plaques (scarring of the pleura), malignant mesothelioma of the pleura and peritoneum, and carcinoma of the lung, especially among those who also smoke cigarettes.

Analysis of the mineral fiber content of the lung in patients with these various diseases has provided a powerful investigative tool to researchers interested in the relationship between fiber burdens and disease. Such studies have shown that when sufficiently sensitive digestion concentration techniques are employed, some asbestos can be found in lung tissue from virtually every adult in the general population.
Pulmonary Alveolar Microlithiasis: A Morphologic Study of Six Cases Including TEM and SEM with EDX Analysis and Immunocytochemistry
Authors: Cole S.R. , Hochholzer L. , Johnson F.B. , Knibbs D.R.
Published: June 2020

Pulmonary alveolar microlithiasis (PAM) is a rare lung disease of unknown etiology characterized by calcified spherules which fill alveolar spaces. Although there are approximately 110 cases of PAM previously reported, only 26 have been confirmed by histologic examination. Increased interstitial fibrous tissue is seen in some cases, and some patients develop shortness of breath. However, many patients remain assymptomatic for years following the diagnosis of PAM.

Six cases from the files of the Armed Forces Institute of Pathology and Hartford Hospital were studied. Light, scanning and transmission electron microscopic studies were performed as were chemical, immunocytochemical and energy dispersive x-ray analysis. Analyses suggest that they are composed in part of mucopolysaccharides and Ca3(PO4)2. Our findings indicate that microliths form initially around a cellular nidus by the deposition of calcium and phosphate salts from the extracellular matrix vesicles of surrounding cells similar to the method previously demonstrated 1n the formation of bone and psammoma bodies. PAM is not usually associated with Identifiable systemic disturbances in calcium and phosphorus metabolism.
Advantage of Electron Spectroscopic Diffraction on Calcified Tissue Sections
Authors: Barckhaus R.H. , Fromm I. , Höhling H.J. , Reimer L.
Published: June 2020

Different stages in the mineralization of calcified tissues can be investigated by electron diffraction. A disadvantage is the strong background below the Debye—Scherrer rings caused by the large massthickness of calcified products and the high ratio (≃ 3) of the inelastic—to—elastic scattering cross—sections of the embedding material. Therefore, a large fraction of the background consists of inelastically scattered electrons with energy losses. The electron spectroscopic diffraction (ESD) mode of an energy—filtering microscope (ZEISS EM902) allows to record diffraction patterns using only the zero—loss electrons which consist of the primary beam, Bragg diffracted electrons and a smaller fraction of elastically scattered electrons between the Debye—Scherrer rings by thermal—diffuse scattering. Small—area diffraction patterns with different camera lengths are generated at the filter—entrance plane and the zero—loss electrons are selected by a slit in the energy—dispersive plane behind the Castaing—Henry filter lens.
A Stationary Solution of High-Energy Electron Reflection (HEER) for An Arbitrary Surface
Authors: MA YIQUN
Published: June 2020

For a long time, the development of dynamical theory for HEER has been stagnated for several reasons. Although the Bloch wave method is powerful for the understanding of physical insights of electron diffraction, particularly electron transmission diffraction, it is not readily available for the simulation of various surface imperfection in electron reflection diffraction since it is basically a method for bulk materials and perfect surface. When the multislice method due to Cowley & Moodie is used for electron reflection, the “edge effects” stand firmly in the way of reaching a stationary solution for HEER. The multislice method due to Maksym & Beeby is valid only for an 2-D periodic surface.

Now, a method for solving stationary solution of HEER for an arbitrary surface is available, which is called the Edge Patching method in Multislice-Only mode (the EPMO method). The analytical basis for this method can be attributed to two important characters of HEER: 1) 2-D dependence of the wave fields and 2) the Picard iteractionlike character of multislice calculation due to Cowley and Moodie in the Bragg case.
A Comparison of Auger and EDX Analysis of Segregation in FCC Alloy Systems
Authors: Partridge Alan , Tatlock Gordon J.
Published: June 2020

During an investigation of grain boundary segregation in the commercial Ni alloy, Nimonic PE16, a detailed comparison was made between the two complementary techniques of Auger electron spectroscopy (AES) and high resolution STEM-EDS analysis. The compositional analysis of grain boundaries by AES can only be performed if the material can be fractured in an intergranular manner. In the case of PE16, an fee material, intergranular failure was induced by charging thin ribbons of the material with hydrogen prior to testing. When bent in a fracture stage, under UHV conditions, these specimens revealed a high proportion of intergranular failure, which was readily amenable to Auger analysis (Fig.1-3 ). For the purpose of comparison, thin foils of PE16 were also prepared and the grain boundary compositions investigated by EDS analysis (Fig.4). These analyses were performed on a HB501 “dedicated” STEM which was capable of producing a 1nm (FWHM) electron probe; and so provided the high spatial resolution required.
Dynamical Calculations of RHEED Intensity Evolution During MBE Growth
Authors: Peng L. -M. , Whelan M. J.
Published: June 2020

Reflection high energy electron diffraction (RHEED) has become well established as one of the most powerful and versatile techniques for growth and surface studies of semiconductor films prepared by molecular beam epitaxy (MBE). In particular the technique of RHEED intensity oscillations has been used routinely to calibrate beam fluxes and alloys composition and to control the thicknesses of quantum wells and superlattice layers.

Although several interpretations have been proposed for the strong oscillations in RHEED intensity during MBE growth, full dynamical calculations have been done only for an artificial surface consisting of a periodic array of surface steps. The enormous amount of computation involved prevents the dynamical theory being applied to a more realistic epitaxically growing system. In this paper we report a simple and practical method for calculating dynamical RHEED from MBE growing surfaces.

We first consider epitaxial growth on a low-index surface. The growth is simulated by using a perfect layer growth model and a diffusive growth model.
The Role of Temperature in Limiting Radiation Damage to Organic Materials in Electron Microscopes
Authors: Lamvik M.K.
Published: June 2020

The intensity of the electron beam in an electron microscope is at once the basis for progress as well as the ultimate limitation in electron microscopy of organic materials. Gabor noted that the highest intensity available for light optics comes from sunlight, which produces an energy density of 2,000 watts/cm2-steradian. The electron sources in early microscopes could produce a million times that amount, and modern sources even more. While the high intensity made good images possible (because numerical apertures used for electron microscopes are less than 1% of the size used in light microscopy) early microscopists feared that such a high flux of charged particles would destroy most specimens, especially organic ones. Although it was soon found that biological specimens could survive observation by electron microscopy, the introduction of double-condenser illumination systems revealed the problem of specimen contamination. In time it became clear that radiation damage was more fundamental than the gross increases or decreases in specimen mass observed in contamination and etching.
Ultramicrotomy as a Technique for Materials Specimen Preparation
Authors: Glanvill S.R.
Published: June 2020

This paper summarizes the application of ultramicrotomy as a specimen preparation technique for some of the Materials Science applications encountered over the past two years. Specimens 20 nm thick by hundreds of μm lateral dimension are readily prepared for electron beam analysis. Materials examined include metals, plastics, ceramics, superconductors, glassy carbons and semiconductors. We have obtain chemical and structural information from these materials using HRTEM, CBED, EDX and EELS analysis. This technique has enabled cross-sectional analysis of surfaces and interfaces of engineering materials and solid state electronic devices, as well as interdiffusion studies across adjacent layers.

Samples are embedded in flat embedding moulds with Epon 812 epoxy resin / Methyl Nadic Anhydride mixture, using DY064 accelerator to promote the reaction. The embedded material is vacuum processed to remove trapped air bubbles, thereby improving the strength and sectioning qualities of the cured block. The resin mixture is cured at 60 °C for a period of 80 hr and left to equilibrate at room temperature.
Alignment of EDX Detectors in Electron Microscopy
Authors: Craven A J , Nicholson W A P
Published: June 2020

When using an energy dispersive x-ray (EDX) detector on an electron microscope, it is important that the region of the specimen irradiated by the electron beam lies in the centre of the field of view of the collimator, which itself must be correctly positioned with respect to the detector crystal. When the microscope column is vented to atmospheric pressure, it is possible to observe the position of the collimator through ports that give access to the specimen region, provided that the detector has a window that can withstand atmospheric pressure. With a windowless detector, this is not possible although it may be possible to align the collimator assembly in this manner. After initial alignment, the detector is often mounted and de-mounted without such a visual check on the alignment, particularly if the microscope is equipped with a gate valve which allows mounting and de-mounting of the detector without venting the microscope column to atmospheric pressure.
An ALCHEMI Investigation of Ternary Site Occupancy in NiAl-Based Alloys
Authors: Munroe P.R. , Baker I.
Published: June 2020

ALCHEMI, or atom location by channeling enhanced microanalysis, is a technique used for determining lattice site occupancies. Previously it has been applied to sublattice occupancy of trace elements in minerals and ternary additions to binary intermetallic compounds. Normally this is performed by acquiring spectra at both positive and negative deviations from the Bragg condition at a suitable plane. (Alternatively, spectra may be recorded at, and away from, a zone axis). So, for example, in a compound AB+X, NX, the integrated x-ray intensity of the element X, is ratioed to both NAand NBfor x-ray spectra acquired at both +sgand -sg. If either NX/NAor NX/NBis independent of sgthis infers that the ternary element occupies the A or B sublattice respectively, thus providing qualitative information. However, if the ternary addition is partitioned between the two sites, this method is unsatisfactory and comparison of the ratios of the x-ray intensities will not provide a clear result.
Crystallographic Effect in X-Ray Microanalysis
Authors: Krishnan Kannan M.
Published: June 2020

The interaction of a fast electron, accelerated through kilovolt potentials in an electron microscope, with a thin foil sample will produce a variety of signals that can be monitored with appropriate detectors to provide information about the crystallography, chemistry and electronic structure of trie sample. In particular, the characteristic x-ray emissions are well understood and form the basis of a simple microanalytical technique by relating the measured x-ray intensities (IA,B) to the elemental weight fractions (CA,B) using the ratio method originally proposed by Cliff and Lorimer , i.e. CA / CB = KAB * IA / IB. This formulation makes the assumption that all the possible atomic sites for the two elements (A and B) in the sample are probed with the same probability by the incident electron beam.

The above assumption is not valid for crystalline samples illuminated with a parallel beam of electrons under strong dynamical diffraction conditions.
Quantitative ALCHEMI With Error Analysis
Authors: Rossouw C.J. , Turner P.S. , White T.J. , O’Connor A.J.
Published: June 2020

The ALCHEMI technique for determining the site distribution fi of an impurity element x on host element lattice sites i is well known: Changes in x-ray emission from host atoms i and impurity x with crystal orientation ARE monitored under strong planar or axial diffraction conditions, and fi derived via a ratio method. However analysis involving count ratios (and ratios of ratios) leads to severe error amplification. Neglect of delocalization leads to further error. To overcome these inherent errors in the standard ALCHEMI method, we make the single assumption that the impurity count Nx may be written as a linear combination of the host atom counts Ni, i.e.

where the coefficients αi and their errors are determined by multivariate analysis. For m separate EDX spectra and fitted parameters αi (i = 1 to v), the criterion v ≤ m must be satisfied for m - v degrees of freedom.
Determination of Space Site of Vanadium in TiAl(Llo) Intermetallic Compound by ALUCHEMI
Authors: Cheng Z. Y. , Gao Ying , Zhu Jing
Published: June 2020

The plastic deformation behaviour of the TiAl (Llo type) intermetallic compound is improved by the vanadium macroalloying (1). The knowledge on the space site of V atoms in TiAl is more important for answer what role the vanadium plays during a deformation. By means of ALUCHEMI (Atom Location Using Channeling ―Enhanced Microanalysis) technique (2-3) it has been found that in the gamma phase of the TiAl compound the V atom is dominantly as a substitutional atom to occupy partial positions of Al atoms in this work. In the TiAl the Ti and Al atoms lie on alternate parallel planes (<001>) , four kinds of possible positions of vanadium atoms were estimated; two of which were substitutional atoms to replace the Ti or Al atom, other two were interstitial atoms to occupy the center of an octahedron as marked in Fig. 1 by О and ⊗ respectively. So using ALUCHEMI technique to determine positions of the V atoms two sets of experiment on channeling effect must be carried out.
MMatrix Description of Rotation Around the Tilt Axes of a TEM Double-tilt Holder and its Applications to TEM
Authors: Qing Liu
Published: June 2020

Double - tilt holder is often used to adjust the specimen orientation during the analysis of crystallology problems. The relationship between a fixed reference orthogonal coordinate, system and the tilt axes of a TEM double - tilt holder is shown in Fig. 1. When the specimen is tilted through an angle β around the second tilt axis (T2) (from β0 to β0 + β ), followed by a tilt α around the longitudinal axis (T1) (from α0 to α0 + α), the new position of a vector g is

T1 and T2 are the transformation matrices related to rotations around the T1 - and T2-axes, respectively, being

Kikuchi map is usually used as a ‘road map’ to adjust the specimen from one orientation to another. However, if the diffraction pattern of a zone axis [u v w] will be obtained from the original position [u0 v0 w0]where the tilt angles are α0 and β0, the tilt angles for crystal specimen orientation adjustment in the double-tilt holder can be calculated using the following two equations which deduced by the above matrices.
Determination of Residual Strains in an Al-SiCw Composite Using CBED
Authors: Rozeveld S.J.
Published: June 2020

It is well established that large stresses may be introduced into Al-SiCw composites by thermal cycling. Due to the large difference in thermal expansion of Al and SiC, a temperature change of ~200°C is sufficient to generate dislocations in the matrix. Dislocation production does not relieve all of the stress and residual strains, which are slightly below the yield point, can remain in the matrix. Although these residual strains will influence both the aging characteristics of the matrix and mechanical response of the composite, very few experimental measurements have been made of the local residual strains in Al-SiCw composites.

The purpose of this investigation was to determine the magnitude of residual strains around individual whiskers in an Al-10 vol.% SiCw composite, which was annealed at 505°C and quenched to room temperature. Convergentbeam electron diffraction (CBED) was used for this investigation since all the information in a CBED pattern originates from a small area defined by the incident probe.
Observation of Dynamic Extinction Lines in the (420) Diffraction Disks of the MgAl2O4 Spinel <100> CBED Pattern
Authors: Liu Dangrong R.
Published: June 2020

Many people have observed dynamic extinction lines in the {200} diffraction disks of the <100> zone axis CBED (convergent beam electron diffraction) patterns of the MgAl2O4 spinel. These dark lines are manifestation of the space group of the material and can easily be explained with the Gjønnes-Moodie theory. However, in addition to the extinction lines in the {200} disks, We have also been able to observe dynamic extinction lines present in the {420} diffraction disks in the same CBED pattern.

The CBED work in this work was carried out with a JEOL-2000FX microscope operated at 100.15 kV. One <100> zone axis CBED pattern is shown in Fig. 1. The dark lines are clearly shown in the {420} disks running through the two perpendicular non-principal axes, in exactly same way as the dark lines in {200} disks.

One can easily explain the dynamic extinction lines in the {200} disks with the Gjønnes-Moodie theory by drawing dynamic scattering pairs oG-Ga and oH-Ha, oK-Ka and oL-La etc. in the diagram (Fig. 2).
CBED Analysis of YBa2Cu3-xAlxOy single Crystals
Authors: Kuroda K. , Matsuhata H. , Saka H.
Published: June 2020

Single crystals of YBa2Cu30y were grown from melting mixture of yttria, barium carbonate and copper oxide contained in alumina crucibles. Crystals grew as platelets with the (001) broad surface. The use of alumina crucibles for crystal growth resulted in incorporation of aluminum to varying extents in crystals of composition YBa2Cu3-xAlx0y, x=0-0.23. Microstructural and microchemical characterization of single crystals were carried out by transmission electron microscopy along with electron dispersive x-ray analysis. Convergent beam electron diffraction (CBED) technique was used to determine crystal symmetry and evaluate symmetry-modification due to twins or local inhomogeneities. Critical voltage effects were studied with respect to oxygen stoichiometry and aluminum concentrations.

The microstructures of YBa2Cu3-xAlx0y single crystals show large twin. domains (Figure la), lamellar twin structures (Figure 2a) and {110}-type tweed pattern modulations (Figure 3a) aparently depending on aluminum concentration. In selected area diffraction patterns splitting diffraction spots along the [110] direction were observed from twined structures and <110> star-shaped streakings around the diffraction spots from tweed structures.
LACBED with Quantitative Anomalous Absorption Corrections
Authors: Rossouw C.J. , Allen L.J. , Miller P.R.
Published: June 2020

An Einstein model for thermal diffuse scattering (TDS) has enabled quantitative calculation of the absorptive potential V'(r). This allows anomalous absorption to be accounted for in LACBED contrast. Fourier coefficients Vg-h of the absorptive component from each atom α are calculated from integrals of the form

where fα is the scattering amplitude and M(Q) the Debye-Waller factor. Integration over the Ewald sphere (dΩ) requires the momentum transfer q to have values up to 2ko (the incident beam momentum). Dynamical ‘dechannelling’ is accounted for by the terms g ≠ h. The crystal absorptive potential is obtained by coherently summing over these atomic absorptive potentials within the unit cell. Unlike the elastic potential, the absorptive potential is a strong function of incident beam energy Eo, since the range of momentum transfer q and associated solid angles dΩ change with the Ewald sphere radius.

Fig. 1 shows a LACBED pattern of the zeroth order beam from Si aligned along a <001> zone axis.
Temporal and Spatial Dynamics of the Actin-Based Cytoskeleton
Authors: Lansing Taylor D.
Published: June 2020

There has been a renaissance and revolution in the use of light microscopy in the biomedical sciences. The renaissance has been due to the importance of studying the temporal and spatial dynamics of ions, metabolites and macromolecules in living cells and tissues. The revolution has been due to the integration of developments in molecular biology, fluorescent probe chemistry, machine vision, and imaging technology. It is now possible to use the living cell as a microcuvette and to explore the chemical and molecular dynamics responsible for cellular functions.

We have been investigating the formation, transport and contraction of stress fibers in Swiss 3T3 cells. Fluorescent analogs of actin, myosin, vinculin and profilin have been investigated in serum deprived cells before, during and after stimulation with thrombin. The activities of these components of the actin-based cytoskeleton have been quantified using time-lapse imaging, fluorescence redistribution after photobleaching, video-enhanced contrast and reflection interference contrast microscopy.