bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Resolution Measurements of Subsarcomere Calcium-Binding Distributions from EPXMA Images
Authors: Cantino M. E. , Eichen J. G.
Published: June 2020

The distribution of calcium binding to thin filaments in vertebrate striated muscle provides clues about the role of calcium in regulation of contraction. A number of studies have suggested that the extent of Ca binding to the thin filament regulatory protein, troponin, is enhanced by the attachment of crossbridges. Electron probe X-ray microanalysis (EPXMA) has provided direct evidence of this enhancement by showing that more Ca is found in the overlap than in the nonoverlap region of sarcomeres in skinned rabbit psoas muscle in rigor. In that study, characterization of the spatial extent of this enhancement was limited by the pixel width of bands (4 pixels) within which Ca counts were averaged at each position across the sarcomere. In order to improve the resolution with which data are extracted from the image we have developed an automated routine for averaging calcium counts from successive columns of pixels across each half sarcomere in the image.
Ion Gradients Across Contractile Vacuole Membranes of Amoebae Grown Under Different Osmotic Conditions
Authors: Shi S.-L. , Bowers B. , Leapman R.D.
Published: June 2020

The contractile vacuole (CV) regulates internal osmolality of free-living protozoa such as amoebae. The CV membrane is known to contain a V-H+ ATPase but the other ion transporters involved in the water pumping mechanism are not yet established. Here we continue our earlier investigation by analytical electron microscopy to measure vacuolar and cytoplasmic ion concentrations inAcanthamoeba castellanii. The present aim is to determine concentrations of ions transported across the CV membrane of amoebae grown under different osmotic conditions.

Subcellular ion concentrations in freeze-dried cryosections can generally be determined from x-ray microanalysis using the Hall method.4However, this approach is not suitable for measuring ion concentrations in the CV, which contains mainly inorganic salts and little, if any, organic compounds. A new method based on electron scattering measurements was therefore devised to deal with this highly aqueous compartment. This method involves: (i) measuring the volume of water in the hydrated cryosectioned vacuole with parallel electron energy loss spectroscopy (PEELS); (ii) measuring the mass of vacuolar salt in the freeze-dried cryosection by dark-field scanning transmission electron microscopy (STEM); and (iii) measuring the ratios of ions by energy-dispersive x-ray spectroscopy (EDXS).
Valence Electron Energy Loss Spectroscopy of Lipids
Authors: Sun S.Q. , Hunt J.A. , Shi S.-L. , Leapman R.D.
Published: June 2020

We have recently demonstrated that chemical mapping by valence electron energy loss spectroscopy (EELS) can provide water distributions in frozen hydrated biological specimens. That investigate also considered the EELS spectra from proteins, nucleic acids and lipids. Next to proteins, lipids the second most abundant component of eukaryotic cells in terms of their mass fraction, but since lipids usually contain a high fraction of saturated carbon bonds they are particularly sensitive to radiation damage in the electron microscope. Here we characterize in further detail the valence EELS spectra of various lipids (arachidic acid, carotene, cholesterol and phosphatidylethanolamine) to determine what information is available about the ratio of saturated and unsaturated bonds and how the EELS fine structure changes as a function of dose.
Secretory PITS in Backswimmers (Heteroptera: Notonectidae).
Authors: Williams R. J. , Dollahon N. R. , Larsen E. , O’Neill S. , Chapman R.
Published: June 2020

In studies of several families of aquatic heteropterans we have found exoskeletal pits not described in the literature. These structures are associated with the lateral margins of the pronotum and/or the dorsal surface, posterior to the scutellum in notonectids, nepids, and corixids. The function of these pits is unknown, but we presumed that they might be either sensory or secretory in nature. We undertook this study of the microscopy of pits in the notonectid, Buenoa margaritacea to learn if either of these functions is consistent with the fine structure.

For TEM, adult insects were submerged in 1.0% paraformaldeyde and 2.0% glutaraldehyde in 0.02M sodium cacodylate buffer with 0.01% calcium chloride at a pH of 7.2, then dissected with a razor blade cleaned with acetone. Tissues were fixed overnight at 4°C in paraformaldehyde and glutaraldehyde, then fixed in 1% osmium tetroxide in cacodylate buffer, dehydrated in a graded series of acetone, embedded in Spurr resin and polymerized at 70°C for 21 hours. Blocks were thin sectioned with a diamond knife, and sections were stained with uranyl acetate and lead citrate. Whole specimens for SEM were similarly fixed, dehydrated in an ethanol series and critical point dried. SEM micrographs of internal pit anatomy were produced by adhering 500nm sections to a glass coverslip, then removing the embedding resin by incubation for 5 minutes in a saturated solution of potassium hydroxide in absolute ethanol, followed by three 20 minute rinses in absolute ethanol and air drying. Cover slips were attached to an aluminum specimen stub and sputter coated for 60 seconds with gold/palladium as were whole insects .
In Situ Electrical and Microstructural Characterization of Individual Boundaries
Authors: Laval J.Y. , Berger M.H. , Cabanel C.
Published: June 2020

In order to get direct information on the relationships between the structural and electrical properties of interfaces, we developed in situ experiments in TEM-STEM and SEM for the characterization of the local behaviour of majority and minority carriers. In particular, we described here our new technique for local determination of interfacial potential barriers in electronic ceramics. This information is completed by voltage contrast imaging in SEM at 1 kV which enables a full map of the distribution of these interfacial barriers to be obtained.

The TEM experiment is schematized in fig. 1. A tungsten microelectrode (100 nm diameter) can be micromanipulated in situ and gently set down on the TEM sample. The contact between the microelectrode and the sample is shown sharply by the modification of extinction contours in each adjacent grain (Fig. 2ab).
Resolution and Sensitivity of Electron Backscattered Diffraction in a Cold-Field Emission SEM
Authors: Isabell T.C. , Dravid V.P.
Published: June 2020

With the advent and development of automated beam control and pattern identification software, the use of electron backscattered diffraction (EBSD) as an analytical tool has increased in recent years. EBSD has been used to determine local crystallography and identification of phases, texturing of polyscrytalline materials, ion implantation damage and the extent of crystal deformation. X-ray diffraction yields crystallographic information, but with lateral resolution on the order of a millimeter. TEM provides local information with resolution of a few angstroms, but this is only over a small lateral region of electron transparency and with poor statistics. EBSD provides a true link between the local crystallographic data and real space information.

The tradeoff between sensitivity and spatial resolution is inherent in all analytical techniques. EBSD is no exception, and determining this tradeoff for this technique is the focus of our work. In a specimen with minimal interfacial strains, as the electron beam is brought near a crystal boundary, the interaction volume of scattered electrons will straddle both crystals, resulting in an overlapped Kikuchi pattern on the imaging phosphor. By aligning such a boundary parallel to the incident electron beam, the “best case” lateral resolution of EBSD can be determined by taking patterns as the probe is stepped in known increments across the boundary. Likewise, the “worst case” resolution can be determined by orienting the boundary perpendicular to the electron beam and stepping the probe. These two cases are shown schematically in Figure 1.
Grain Boundary Engineering for Intergranular Fracture and Creep Resistance
Authors: Palumbo G. , Lehockey E.M. , Lin P. , Erb U. , Aust K.T.
Published: June 2020

Previous studies (see review) have shown that grain boundaries crystallographically described by low Σ Coincidence Site Lattice (CSL) relationships can often display a high resistance to intergranular sliding, cavitation, and fracture; these boundaries satisfying Brandon’s criterion (Δθ≤15°Σ−1/2), for Σ≤29. Figure 1 summarizes the grain boundary structure-dependence of intergranular cracking on stressed C> rings (0.5% strain) of Alloy 600 (75Ni-15Cr-10Fe) following autoclave exposure to 10% NaOH at 350°C for 3000 hours. Grain boundaries connected to intergranular crack paths were characterized using electron backscattered diffraction (EBSD) in a SEM. As shown in Fig. 1, general grain boundaries (Σ≤29) are the preferred paths for intergranular cracking; ‘special’ grain boundaries (Σ>29) show a high resistance to intergranular attack.

In quantifying the effect of ‘special’ grain boundary frequency on bulk intergranular cracking susceptibility, a geometric model has been formulated which considers that a propagating crack can arrest at a triple junction when both of the available intergranular paths for crack continuation are inaccessible owing to either (1) intrinsic resistance to cracking (e.g., low Σ CSL grain boundary) or (2) unfavourable orientation to the applied stress axis. Figure 2 summarizes the effect of ‘special’ grain boundary frequency on the probability of intergranular crack propagation as predicted by this model. Increasing the fraction of ‘special’ grain boundaries by only moderate amounts can considerably reduce the maximum attainable intergranular crack length in a material. For example, the probability of a crack propagating beyond 5 grain diameters is approximately 35% in a material having 15% special grain boundaries; the probability is reduced to approximately 1% in a material containing 45% ‘special’ grain boundaries, and to less than 0.001% in a material containing 75% special grain boundaries. These concepts have been recently applied in developing a proprietary thermomechanical processing methodology which serves to increase the frequency of special grain boundaries in austenitic stainless alloys to values in excess of 60%; such a treatment having been demonstrated to render Alloy 600 (see Fig. 1) immune to intergranular cracking.
Equilibrium Shapes of Pb Inclusions at 90° Tilt Grain Boundaries in Al
Authors: Johnson E. , Dahmen U. , Xiao S.-Q. , Johansen A.
Published: June 2020

Ion implantation of lead in aluminum leads to spontaneous phase separation and formation of dense distributions of nanosized lead inclusions[1]. The inclusions have fee structure, and despite the large lattice mismatch (aA1 = 0.4048 nm and aPb = 0.495 nm) they grow in parallel-cube topotaxy with the matrix. Their shape is cuboctahedral with larger {111} facets and smaller {100} facets which is the minimum- energy shape for an fee crystal in equilibrium with its vapor, as calculated by considering only nearest neighbor bonds. Implantation of polycrystalline aluminum films is accompanied by preferential nucle- ation and enhanced growth of inclusions in the grain boundaries. In adapting their equilibrium shape, grain boundary inclusions will be subject to a larger number of constraints than inclusions in the bulk matrix. This may result in a variety of morphologies characteristic for different types of grain boundaries.

In the present study we have used a well-defined bicrystal geometry to study the morphology and structure of lead grain boundary inclusions in mazed bicrystal aluminum films containing mainly 90°<110> tilt boundaries with fixed misorientation but variable inclination[2]. It was found that the shape, size and orientation of the inclusions in the grain boundaries depend on the inclination, i.e. the orientation of the grain boundary plane. Inclusions were all single crystalline and invariably faceted toward one aluminum grain and more rounded toward the other grain (fig.l). Independent of grain boundary inclination, the faceted side was a section of the cuboctahedral equilibrium shape of inclusions in parallel topotaxy with the bulk aluminum matrix. The rounded side, where the inclusions were rotated by 90° with respect to the aluminum lattice, approximated a spherical cap consisting partly of somewhat flatter segments with complex faceting, illustrating the lack of distinctly flat low-energy facets.
On the Faceting of Polar Ceramic Surfaces: Microscopy and Holography Studies of MGO(111) Surfaces
Authors: Gajdardziska-Josifovska M. , Frost B. G. , Völkl E. , Allard L. F.
Published: June 2020

Polar surfaces are those crystallographic faces of ionically bonded solids which, when bulk terminated, have excess surface charge and a non-zero dipole moment perpendicular to the surface. In the case of crystals with a rock salt structure, {111} faces are the exemplary polar surfaces. It is commonly believed that such polar surfaces facet into neutral crystallographic planes to minimize their surface energy. This assumption is based on the seminal work of Henrich which has shown faceting of the MgO(111) surface into {100} planes giving rise to three sided pyramids that have been observed by scanning electron microscopy. These surfaces had been prepared by mechanical polishing and phosphoric acid etching, followed by Ar+ sputtering and 1400 K annealing in ultra-high vacuum (UHV). More recent reflection electron microscopy studies of MgO(111) surfaces, annealed in the presence of oxygen at higher temperatures, have revealed relatively flat surfaces stabilized by an oxygen rich reconstruction. In this work we employ a combination of optical microscopy, transmission electron microscopy, and electron holography to further study the issue of surface faceting.
1/60 Sec Time-Resolved High-Resolution Electron Microscopy of Step-Diffusion of Tungsten Atoms on MgO (001) Surfaces
Authors: Tanaka N. , Kimata H. , Kizuka T.
Published: June 2020

Surface-diffusion process of atoms is one of the important factors for understanding various types of surface-related phenomena such as thin-film growth and catalysis reaction[l]. Development of field ion microscope (FIM) was a great breakthrough for the study of the process in atomic level. The diffusion process of Rh and Re atoms on tungsten surfaces was quantitatively studied, and the barrier potential (Ed) and the pre-exponential factor (D0) were successfully determined[2]. Recent development of scanning tunneling microscope (STM) has also enabled us to measure directly the moving of Pb and Sb-atoms on Ge and Si (111) surfaces[3, 4]. The time-resolution of these methods is, however, not sufficient to trace the diffusion process in detail.

In previous papers, we reported the first experiment of tracing the diffusion process of tungsten(W)-atoms on terrace-regions of MgO (001) surfaces in the time-resolution of 1/60 s.using dynamic high resolution electron microscopy[5,6]. The values Ed=0.18 eV and Do=1.5x10−14 cm2/s were successfully determined from the video-tape images. In the present study, we have observed diffusing atoms along the surface-steps and studied the phenomena quantitatively.
A Scalable Approach to Teleoperation
Authors: Taylor J. , Parvin B.
Published: June 2020

Due to the fast pace of computer instrumentation and technology, we are quickly approaching an age where on-line use of expensive research facilities will become commonplace. The consequences of this trend will be multifaceted. It will allow scientist and researchers to perform experiments and access data with greater ease without the burden some overhead associated with working onsite. It will allow for the on-line storage and analysis of data. And lastly, an ideal testbed will be provided for integrating intelligent man-machine interfaces in order to reduce labor intensive tasks. This will simplify the control of complicated instruments via automation of the controls whose human control is not essential. Unfortunately, attempts at building a common platform for remote operation will face several problems. First of all, a successful general purpose architecture will frequently need to be extended in order to perform new functions as well as utilize new hardware. Similarly, the continued development of new microscopes, stage controls, etc. will undoubtedly create incompatible interfaces which will break presently working systems. Lastly, the environment that such a system will operate will likely be characterized by heterogeneous hardware and software. Based on the experience of building on-line systems for use of optical and electron microscopes, we propose a scalable system architecture based on the principles of object oriented design and analysis, a machine independent user- interface based on Java, and a software bus that supports distributed objects over the network.
Development of an SEM Digital Image Capture and Storage System and Associated Distributed Viewing Interface
Authors: Chu Benjamin R. , Moran Patrick B. , Schaedler Joseph B.
Published: June 2020

The advent of cheaper and faster network, desktop and storage products coupled with maturing digital image capture technology for microscopy tools is allowing for innovative ways to enhance the way microscopy images are captured, stored and viewed. The SEM Laboratory at IBM’s Advanced Semiconductor Technology Center (ASTC) is trying to leverage the combination of networked computing power and image capture technology to reduce costs, improve productivity and provide our internal customers with a product that better fits into their overall data analysis and documentation strategy.

ASTC's SEM Lab provides physical analysis support for over 200 semiconductor engineers working on advanced memory and logic process technologies. Over 15,000 requests (or jobs) are submitted annually to the SEM Lab which result in several hundred thousand images which are used to monitor in-line process lots, verify experimental lots and to aid in failure analysis. The original thrust of this project was to reduce the SEM Lab annual film budget (∼$400K), but changing customer needs necessitated a system that would also allow for storage, retrieval and viewing of captured SEM images.
A WWW Interface for Viewing and Searching Sets of Digital Images
Authors: Thompson Mary , Bastacky Jacob , Johnston William
Published: June 2020

As microscope images are increasingly being created and stored digitally, researchers are in need of tools to help them organize and quickly search these collections. Because of the large amount of storage taken up by digital images they are frequently kept on bulk storage systems remote from the microscopist’s PC or workstation. The interface to these mass storage systems may be awkward and viewing large, remotely stored images can be very slow, making it difficult for the user to find a desired image.

The LBNL Image Library was designed and implemented to provide a system to help researchers organize, browse and search through digital image collections, especially collections where the original images are stored off-line in a mass storage system. We also wanted to facilitate co-operative research by allowing access to the images by specified users at local and remote sites.
Virtual SEM 1.2 - Training in SEM
Authors: Griffin B.J. , Riessen A. van
Published: June 2020

The greatest barrier to effective training in electron microscopy is the initial apprehension within students based on the complexity and cost of the instrumentation. A second, and today more real barrier, is the actual cost of hands-on training in courses, in terms of both instrument and staff resources. The software described below was developed to eliminate these barriers, to include a ‘fun’ component to relax students, to improve the effectiveness of short training courses and to act as a stand-alone resource for new SEM operators.

A software package utilising multimedia components, “Virtual SEM 1.2”, has been developed to simulate the use and operation of a basic scanning electron microscope (SEM). Background SEM theory is provided through introductory tutorials and an automatic assessment section allows independent evaluation of student progress. The package is appropriate for entry level operator training and also as a reference for general operation.
Sub Surface Imaging Using a Toroidal Backscattered Electron Energy Spectrometer in a Scanning Electron Microscope
Authors: Rau E I , Robinson VNE
Published: June 2020

In a SEM, an object under examination is scanned by a focused electron beam, of energy typically 2-30 keV. Some of the incident electrons are scattered out of the sample, carrying with them depth information from the internal structure of the sample. By detecting BSEs in a definite energy range, it is theoretically possible to separate images of individual layers of a three-dimensional sample, ie, perform a kind of instrumental tomography. Additionally, detecting BSEs on an energy separation basis gives another degree of freedom to microscopists to determine greater specimen information. To do this, a suitable BSE energy filter or spectrometer is required.

To be effective and produce high quality images, a BSE spectrometer should have a working distance of less than 40 mm. It should be axially symmetric with the electron beam passing through the center of the analyser, impinging on the specimen normal to its surface. The specimen being scanned must be placed in the space free from the analysing field of the spectrometer, which should not introduce any magnetic fields. Using these criteria, computer simulations were performed to determine the equipotentials and trajectories of electrons in cylindrical, hyperbolic, sector spherical and sector toroidal electrostatic energy analysers. The results showed that the above requirements could be satisfied by a toroidal energy analyser, which also has the advantage over the others as to the coupling coefficient, relative aperture dimensions and energy resolution capabilities.
Mosaic Mapping: A Means of Tiling Images to Shorten Acquisition Speed for Lower - Magnification SEM Images and Wavelength Dispersive Spectrometers (WDS) X-Ray Maps
Authors: Geller J.D. , Herrington C.R.
Published: June 2020

The minimum magnification for which an image can be acquired is determined by the design and implementation of the electron optical column and the scanning and display electronics. It is also a function of the working distance and, possibly, the accelerating voltage. For secondary and backscattered electron images there are usually no other limiting factors. However, for x-ray maps there are further considerations. The energy-dispersive x-ray spectrometers (EDS) have a much larger solid angle of detection that for WDS. They also do not suffer from Bragg’s Law focusing effects which limit the angular range and focusing distance from the diffracting crystal. In practical terms EDS maps can be acquired at the lowest magnification of the SEM, assuming the collimator does not cutoff the x-ray signal. For WDS the focusing properties of the crystal limits the angular range of acceptance of the incident x-radiation. The range is dependent upon the 2d spacing of the crystal, with the acceptance angle increasing with 2d spacing. The natural line width of the x-ray also plays a role. For the metal layered crystals used to diffract soft x-rays, such as Be - O, the minimum magnification is approximately 100X. In the worst case, for the LEF crystal which diffracts Ti - Zn, ˜1000X is the minimum.
Stem Dark-Field Image Using A 200-kV AEM
Authors: Tomita T. , Honda T. , Kersker M.
Published: June 2020

Interpretation of the high resolution transmission image typically requires simulation since the contrast changes in a complicated way due to changes in focus and specimen thickness. The contrast in images formed by collecting high angle forward scattered electrons in STEM does not change with changes in thickness or defocus.

Until recently, high angle annular dark field (HADF) images were obtained only from instruments using cold field emission guns. Recently we have attempted to obtain HADF images using Schottky (ZrO/W(100)) thermal field emission and using a 200kV instrument designed as a comprehensive TEM/STEM. Advantages of the ZrO/W emitter are easy operation, very good short and long term stability, high brightness, and narrow energy spread. This microscope, The JEM2010F with thermal field emission, allows subnanometer analysis with EDS(spot, line, and mapping), EELS, holograms, etc, and has a standard TEM imaging system for high resolution imaging and for various diffraction modes, viz., CBED, selected area, Tanaka, etc.
The limitations of quantitative EDS analysis at low voltage
Authors: Nockolds C. E.
Published: June 2020

There are several reasons for carrying out x-ray microanalysis at low beam energies. In conventional electron probe microanalysis with wavelength dispersive spectrometers (WDS) there has been a considerable effort in recent years to improve the accuracy of quantitative analysis of the “light” elements B, C, N and O. The shapes of the low energy K x-rays and the L x-rays of the first transition series metals are also being studied with the aim of determining the chemical environments of the atoms in a sample. In most materials these soft x-rays suffer from very high absorption, and reducing the depth of the interaction volume by lowering the beam voltage to 5kV or below leads to a much reduced absorption correction. In scanning electron microscopy the introduction of thin window energy dispersive spectrometers (EDS) has made it possible to look at low energy x-rays and here the main interest in working at low voltages is in the improvement of the resolution of analysis.

In this paper the limitations of SEM/EDS low voltage analysis will be examined, and possible solutions to some of the problems explored. It will be assumed that the aims are to achieve quantitative analysis at the best possible spatial resolution.
A simulation program for quantitative procedure in EPMA
Authors: Merlet Claude
Published: June 2020

In the last ten years the development of new X-ray depth distribution models in electron probe microanalysis (EPMA), has allowed to obtain accurate quantitative programs for stratified and massive samples. With these new quantitative methods, for the energy lines greater than 1keV and for massive samples, the results of the quantification are independent of the accelerating voltage (for an excited line). Nevertheless, for light elements, and for soft X-ray emission in complexe compounds, the choice of these optimum experimental conditions is not trivial. Moreover, the physical parameters and boundary conditions of the measurements are not well known.

In an attempt to choose the optimum accelerating voltage, and to solve some difficulties in the quantification of low energy lines, a software (freeware) has been developed on PC and under the WINDOWS operating system. The calculation procedure is based upon the double partial gaussian profile ϕ(ρz) (recently developed for massive compounds). This description, flexible, precise and mathematically simple allows to compute rapidly the X-ray intensities. The program, which has been designed mainly for WDS electron probe, uses graphic simulations, and includes two sections:
EPMA quantitative x-ray mapping
Authors: Thiot J. F. , Pouchou J. L.
Published: June 2020

Quantitative X-ray mapping has always been one of the ultimate goals of many X-ray microanalysis application programs. However, only semi-quantitative X-ray mapping (peak intensities) is commonly used in WDS and EDS techniques. EDS maps are easier to produce, because the multichannel detection gives direct access to the intensities, and also because beam scanning may be used over wide areas without any danger of spectrometer “defocusing”. WDS mapping, because of the monochannel detection, has most of the time been limited to one map per spectrometer. A few attempts have been made in both techniques to produce a quantitative map by calibration, i.e. using a few quantitative analyses performed on some pixels to calculate the composition at each pixel of an image. What we propose here is to improve the WDS acquisition scheme and the automation of the quantitation to the point where the user can collect automatically all X-ray maps of the elements in the sample and then run a quantitative routine which automatically calculates the corresponding composition images, through the usual ϕ(ρz) procedures (PAP/XPP).
The examination of yttrium ion-implanted alumina with energy-filtered transmission electron microscopy
Authors: Hunt E. M. , Hampikian J. M. , Evans N. D.
Published: June 2020

Ion implantation can be used to induce complex alterations in the optical response of insulators through the formation of embedded nano-sized particles. Single crystal alumina has been implanted at ambient temperature with 170 keV Y+to a fluence of 5 × 1016ions/cm2. Ion channeling, Knoop microhardness measurements, and transmission electron microscopy (TEM) indicate that the alumina surface layer was amorphized by the implant. TEM also revealed weakly diffracting nano-sized crystals ≈12 − 13 nm in diameter as seen in Figure 1. These nanocrystals are randomly oriented, and exhibit a face-centered cubic structure (FCC) with a lattice parameter of 0.41 nm ±0.003 nm. Energy dispersive spectrometry (EDS) shows that these nanocrystals are rich in aluminum and yttrium and poor in oxygen relative to the surrounding amorphous matrix. The similarity between this crystallography and that of pure aluminum (which is FCC with a lattice parameter of 0.40 nm), coupled with the qualitative nanocrystal composition indicated by EDS, suggests that they are metallic aluminum nanocrystals with a slightly dilated lattice parameter, possibly due to the incorporation of a small amount of yttrium.
Chemical Effects of Lanthanides and Actinides in Glasses Determined with Electron Energy Loss Spectroscopy
Authors: Fortner Jeffrey A. , Buck Edgar C. , Ellison Adam J. G. , Bates John K.
Published: June 2020

The chemical and structural environments of f-electron elements in glasses are the origin of many of the important optical, electronic, and magnetic properties of materials incorporating these elements. Thus, the oxidation state and chemical coordination of lanthanides and actinides in host materials is an important design consideration in optically active glasses, magnetic materials, perovskite superconductors, and nuclear waste materials.

The energy loss spectra of the lanthanides are characterized by sharp 3d3/2→4f5/2 (M4) and 3d5/2→4f7/2 (M5) lines, the relative intensities of which are determined by the 4f-shell occupancy of the excited ion. For the light lanthanides, the dependence of these relative peak heights on 4f-shell occupancy is quite pronounced. In particular, the ratio of the M4 to M5 peak areas in the second derivative spectra is extremely sensitive to the formal valence of the multivalent elements Ce and Pr. In figure 1, the EELS spectra are presented for Ce(III) and Ce(IV) in well-characterized reference materials.
Determination of local dielectric function in donor-doped barium titanate
Authors: Katti Kalpana S. , Qian Maoxu , Sarikaya Mehmet
Published: June 2020

Barium titanate (BaTiO3) is one of the basic materials for electroceramic components and is also used for electrooptic applications. When certain donor dopants such as Nb are introduced, it exhibits the property of positive temperature coefficient of resistance (PTCR) wherein there is a jump in resistance of several orders of magnitude at the transition temperature (∼ 120°C). Although considerable work has been done to understand the influence of dopants on bulk samples, it is not clearly known what the detailed distribution of the dopant is and how it affects local properties.

This paper addresses the problem of how the addition of Nb affects local properties of BaTiO3. This is done by using electron energy loss (EEL) spectroscopy which probes the local electronic structure. We use the Kramers-Kronig (KK) analysis to compute the local dielectric function from the low loss electron energy loss data.
Interlaboratory Study of K Factor Determination by Asbestos-Analysis Laboratories
Authors: Turner S. , Steel E.B. , Crankshaw O.S.
Published: June 2020

The National Voluntary Laboratory Accreditation Program (NVLAP) of the National Institute of Standards and Technology (NIST) has been accrediting laboratories for the analysis of asbestos by transmission electron microscopy since 1990. As part of the quality assurance procedures for the program, laboratories are required to determine k factors for Na, Mg, Si, Al, Ca and Fe. An interlaboratory study has been conducted by NIST and the Research Triangle Institute (RTI) in which laboratories analyzed thin film standards SRM 2063 or SRM 2063a. This work reports results of initial analysis of the data.
Integrated computer data acquisition and control in analytical electron microscopy
Authors: Weiss J. K. , de Ruijter W.J. , Cosart Douglas. W.
Published: June 2020

Computers were considered to be mainly “add-on” equipment for analytical electron microscopes until only the last several years. Before that time, although most microscopes had been microprocessor-controlled for at least five years, the only use of more conventional computers was for controlling spectrometers connected to the microscope. The fundamental limitation of computers for scanned imaging was mostly one of speed. Spectra could be acquired and displayed in real time even by computers of early 1980’s vintage, whereas only modern computers are capable of acquiring and displaying video rate digital scanned images.

The result of this fundamental difference in signal rates between imaging and spectroscopy is that separate computer systems have been developed for imaging and spectroscopy. Even in the cases where spectroscopy systems (most notably EDX systems) have integrated some image acquisition capabilities, or where imaging systems have integrated some spectroscopy, the design of the systems is virtually always centered around either imaging or spectroscopy.
Examples of 3D morphological image analysis in microscopy
Authors: Jeulin D.
Published: June 2020

Image analysis of materials microstructure is a complementary means of characterization in addition to more usual properties, such as chemical analysis or physical measurements. In this lecture are introduced some of the most recent developments in the implementation of 3D morphological image analysis. Usually, the available information in Quantitative Microscopy is two-dimensional, as obtained from polished sections. However 3D data may be obtained: the topography of rough surfaces can be accessed from a stylus instrument or from a confocal optical microscope; serial sections can be prepared and examined in the optical microscope; sometimes serial sections can be obtained in a non destructive way, using the optical confocal microscope for transparent media, or X-ray tomography. With these data, 3D morphological processing can be used to get more specific information on the microstructure. Mathematical Morphology operations, defined in a more general background, are easily performed on 3D images by software developed on standard computers.
Extracting 3-D information from SEM and TEM images: approches and applications in the physical sciences
Authors: L’Espéranee Gilles , Dionne Martin , Jeulin D. , Demarty C. H. , Tremblay S. , Perrier E.
Published: June 2020

Techniques for extracting 3-D information from TEM samples in life sciences have considerably progressed in recent years. One approach has been the use of serial sections prepared by ultramicrotomy from which the volume of the sample and of various constituents can be reconstructed.

In the case of engineering materials, however, ultramicrotomy generally induces severe deformation resulting in a large density of structural defects (dislocations, stacking faults etc.). This leads to significant diffraction contrast effects which mask microstructural features such as second phase particles, precipitates etc. Recently, a series of TEM bright field images taken at different tilts have been used in combination with image analysis to determine the volume fraction (Vf) of second phase particles in thin foils of aluminum alloys. Although the technique was successful to remove most of the diffraction contrast effects and to make the particles visible, the need to acquire and process a large number of images makes the technique laborious and can lead to artefacts.
Role of microstructure in determining the tribological properties of ceramic materials
Authors: Doğan C.P. , Hawk J.A.
Published: June 2020

It is well known that experimentally-determined values of wear resistance are not materials’ constants, but rather measured responses to a particular set of conditions imposed by a specific wear environment. Nonetheless, a material’s tribological performance is often estimated based on its bulk material properties. For applications requiring abrasive wear resistance, for example, ceramic materials are traditionally selected based on their hardness and fracture toughness, which are assumed to be proportional to the wear resistance. However, recent studies have indicated that for many commercially-important ceramic materials, subtle differences in the microstructure (not always reflected in measured values of bulk hardness and fracture toughness), can lead to large variations in the abrasive wear resistance.

A number of microstructural variables can influence the tribological properties of a ceramic material: matrix grain size, matrix grain shape, the presence of intra-and inter-granular second phases, and the presence of transforming second phases (in zirconias and zirconia-toughened ceramics, for example).
TEM study of franklinite-hetaerolite (ZnFe2O4-ZnMn2O4) exsolution intergrowths
Authors: Gong W.L. , Wang L.M. , Ewing R.C.
Published: June 2020

The spinel structure-type is derived from ccp oxygen packing by cation occupation of one quarter of the tetrahedral and one half of the octahedral interstices with a general stoichiometry of AB2O4. Franklinite, ideally ZnFe2O4, was the dominant ore mineral of zinc at the great Franklin and Sterling Hill zinc deposits, New Jersey. Although the chemistry of franklinite conformed to the spinel formula, the composition showed a wide range in the proportions of iron, zinc, and manganese. The microscopic examination of polished sections of the Franklin spinel revealed oriented exsolution intergrowths of franklinite, magnetite (Fe2+Fe3+2O4), and gahnite (ideally ZnAl2O4). In this contribution, the exsolution intergrowths of franklinite and hetaerolite (ideally ZnMn2O4) are well characterized using JEM 2000FX and JEM 2010 electron microscopes operated at 200 keV.
The β - 3C to α - 4H transformation in SiC with Al, B, and C additions: Kinetics dominated by growth akin to ostwald ripening
Authors: MoberlyChan Warren J. , Cao J. J. , DeJonghe L. C.
Published: June 2020

The cubic-to-hexagonal phase transformation upon heating SiC has been a focus and/or precondition of hundreds of research studies. In single (or large) crystal SiC, partial dislocation motion propagates stacking faults to invoke the transformation, analogous to the classic FCC-HCP transformation in Co. The hexagonal phase can exist in >200 different stacking modulations of planes of Si-C tetrahedra, with the α-6H polytype regarded as the high temperature equilibrium phase. (“6” is the repeat stacking in a unit cell.) The propensity of stacking faults in all SiC materials provide the nuclei for the transformation. Most transformation studies of polycrystalline SiC cite the work of Heuer, et al., which describes a transformation similar to that in single crystals. The Heuer model incorporates grain growth by observing the nucleated alpha phase as sandwiched between “sheaths” of beta phase, with the sheaths continuing to grow and “protect” the growing alpha phase throughout the transformation. Grain growth incurred during processing is typically treated as kinetically independent of the transformation.
Low-voltage microscopy and position-tagged spectrometry of ceramic microstructures
Authors: Friel J. J , Greenhut V. A.
Published: June 2020

Ceramic microstructures are ideally suited for low-voltage field emission microscopy on uncoated samples. Most elements of interest in ceramics have useful X-ray lines below 5 keV, thus permitting the use of accelerating voltages between 3 and 8 kV. One analytical consequence of the use of low voltage is a reduced interaction volume with the electron beam, so that X-ray maps can be collected at submicrometer resolution. To produce usable maps at low voltage, the SEM must be capable of sufficient beam current, and the X-ray detector geometry must be optimal. Another way to optimize X-ray microanalysis is to collect an entire spectrum at every point in the microstructure even at high resolution. Although this capability would permit an X-ray spectrum to be displayed from one pixel, a much more productive approach is to create a spectrum based on all pixels of a particular phase.
TEM/AEM characterization of fine-grained clay minerals in very-low-grade rocks: Evaluation of contamination by empa involving celadonite family minerals
Authors: Li Gejing , Peacor D. R. , Coombs D. S. , Kawachi Y.
Published: June 2020

Recent advances in transmission electron microscopy (TEM) and analytical electron microscopy (AEM) have led to many new insights into the structural and chemical characteristics of very finegrained, optically homogeneous mineral aggregates in sedimentary and very low-grade metamorphic rocks. Chemical compositions obtained by electron microprobe analysis (EMPA) on such materials have been shown by TEM/AEM to result from beam overlap on contaminant phases on a scale below resolution of EMPA, which in turn can lead to errors in interpretation and determination of formation conditions. Here we present an in-depth analysis of the relation between AEM and EMPA data, which leads also to the definition of new mineral phases, and demonstrate the resolution power of AEM relative to EMPA in investigations of very fine-grained mineral aggregates in sedimentary and very low-grade metamorphic rocks.

Celadonite, having end-member composition KMgFe3+Si4O10(OH)2, and with minor substitution of Fe2+ for Mg and Al for Fe3+ on octahedral sites, is a fine-grained mica widespread in volcanic rocks and volcaniclastic sediments which have undergone low-temperature alteration in the oceanic crust and in burial metamorphic sequences.
Transmission electron microscope observation of diamond / WC interface
Authors: Kim Geun-Hong , Chun Chang-Hwan
Published: June 2020

Commercial diamond coated WC-Co cutting tool has been investigated by transmission electron microscope (TEM) to understand the nucleation and growth of diamond on WC substrate. Cross-sectional specimens have been prepared by mechanical polishing followed by ion milling. TEM observations have been performed using analytical TEM, JEM 4000FX (JEOL Ltd.).

The surface of the coated diamond is composed of grains of 2 - 5 μm in diameter. Each main grain is formed by columnar subgrains of 10 - 50 nm in diameter with similar orientations. Cobalt, a binder in cemented carbide, within 5 μm in depth from the carbide surface has been found to be removed to increase the adhesion of diamond.

One of diamond subgrains, which has been grown large in [001] orientation on WC grains is shown in Fig. 1. High density of twins are found on (111) plane starting from WC grain boundaries. It is thought that the interfacial stress between diamond layer and WC grains is accommodated by these twins.
CBED and HREM study of decagonal quasicrystals
Authors: Tanaka M. , Tsuda K. , Saitoh K.
Published: June 2020

Decagonal quasicrystals have been investigated by convergent-beam electron diffraction (CBED) and transmission electron microscopy. Figure 1 shows possible pentagonal and decagonal point groups. The CBED method has revealed that the decagonal quasicrystals found so far belong to the space groups of noncentrosymmetric P10m2 and centrosymmetric P1O5mmc.

Dark-field microscopy has revealed the existence of inversion domains with an antiphase shift of c/2 at the domain boundaries in the alloys with space group m2.2 High-resolution electron microscopy (HREM) has revealed the existence of specific pentagonal atom clusters in the Al-Ni-Fe, Al-Cu-Co and Al-Ni-Co alloys. Figure 2 shows a HREM image of Al70Ni15Fe15 belonging to space group m2. The atom clusters of an about 2nm diameter are clearly seen as indicated by a black circle. The clusters are polar or noncentrosymmetric due to the dark pentagon at their centers. All the clusters in domain A have one sense of polarity and those in domain B the other sense. It should be noted that the HREM image of the cluster columns was found to be pentagonal at an accelerating voltage of 200kV but nearly decagonal at higher than 300kV.
α-AlMnSi phase to a bcc structure by XE+ ion-beam irradiation
Authors: Guo Y.X. , Wang L.M. , Ewing R.C.
Published: June 2020

AlMnSi alloy system has attracted great attentions since the first report on the icosahedral quasicrystal materials in 1984. The rapidly quenched AlMnSi alloy around the stoichiometry of the α-AIMnSi phase (α-phase below) may form icosahedral quasicrystals. And the structure unit of the α-phase is of near icosahedral symmetry. The α-phase has a cubic structure with space group Pm3 (a= 1.268 nm). In each unit cell there are 138 atoms. The most important structure unit in this phase is the so-called MacKay icosahedron. In such a structure unit, 12 Al atoms are decorating the vertices of an icosahedron. Surrounding this icosahedron is another same oriented icosahedron of 12 Mn atoms, which is about twice the diameter of the former. Furthermore, 30 Al atoms define a shell outside the two inner icosahedra with each atom sitting at the midpoint just out of the Mn icosahedron edges. In the structure of α-phase, the icosahedra are slightly distorted and are connected along those of their three fold axes that coincide with the <111> direction of the cubic lattice.
Ultrastructural morphology of the dorsal lobe of the prostate gland in cadmium and zinc-treated rats
Authors: Bataineh Z.M. , Hailat N. , Lafi S. , Hani I. Bani
Published: June 2020

We have demonstrated in previous study that the nucli of the cells of the posterior lobe of the prostate gland sequesters less zinc in cadmium and zinc treated rats compared to the normal ones. In this study we will evaluate if the variation in the nuclear zinc concentration is associated with a concomitant variation in ultrastructural morphology. Two groups of animals were injected with 2mg/kg and 10 mg/kg cadmium chloride and zinc sulfate, respectively. Another group served as control. Dorsal lobe of the prostate gland from the three groups were prepared for conventional E.M study. Grids were examined and photographed by Hitachi-700 electron microscope.

Figure (1) shows prostatic cells from the posterior lobe of the prostate gland of a normal rat. The rough endoplasmic reticulum form a narrow continuous cisternae, most abundant at the lateral portion of the cell and sometimes acquired whorl-shaped appearance. Well-developed Golgi apparatus with abundant secretory vesicles are shown.