bluuebunny/crossref_metadata_2025 huggingface dataset:
The Intrinsic Formation Of Localized Electronic States At [001] Tilt Grain Boundaries In YBa2Cu3O7 And Their Effect On Jc
Authors: Buban J P , Browning N D
Published: July 2020

Grain boundaries have long been known to have a deleterious effect on the superconducting critical current that can be carried by YBa2Cu3O7-δ. Recent theoretical analyses have proposed that the origin of this behavior may be band bending, which results in the depletion of charge carriers at the grain boundaries. For this to occur in these p-type superconductors there must, by definition, be a high density of localized donor states in the boundary plane. Here we describe a structural feature intrinsic to all [001] tilt boundaries that may be the origin of these localized states.

Direct atomic-resolution images of asymmetric [001] tilt grain boundary structures have been obtained using the Z-contrast imaging technique. The grain boundaries are observed to be composed of distinct structural units, as shown in figure 1. Within these structural units, a 2×1 reconstruction of the CuO columns is seen to occur. This reconstruction, which is caused by the constraint imposed on the structure by the sizes of the component atoms, leads to effective oxygen vacancies in the grain boundary plane (figure 2). Further oxygen annealing of the boundary cannot fill these vacancies as there is no space in the structure for more oxygen atoms.
On The Formation Of Diffusion Layer Between Cr Film And Glass
Authors: Jiang N , Silcox J
Published: July 2020

Chromium films are commonly used as a metal “glue” layer because of good adhesion to glass. It is believed that an intermediate oxide layer is formed during deposition, since Cr has a very strong affinity for oxygen. For example, a graded Cu/Cr/CrOx/SiO2 structure ensures excellent adhesion of Cu to glass, whereas Cu exhibits poor adhesion to most dielectrics. In our recent study, however, a diffusion layer, Cr2O3+SiOy, was observed between CrOx and SiO2 (glass) substrate. It is quite likely that this diffusion layer is responsible for the good adhesion of Cr film to glass.

The relative compositions of the major components across the interface are shown in Fig 1. A Cr film was evaporated on Corning Code 1737 glass (Al2O3-B2O3-SiO2 with ˜67at.% Si02) substrate at room temperature (RT) and subsequently covered with about lOnm Cu. A 5nm'wide diffusion layer is seen. The corresponding regions are also indicated in Fig 2, an Annular Dark Field (ADF) image whose contrast is approximately proportional to the density if the thickness is assumed uniform.
Determination Of Coherency Strains Around Particles In Ni-Al Alloys By HREM And CBED
Authors: Calderon H A , Cruz JJ , Calzado L , Kisielowski C , Wang YC , Kilaas R
Published: July 2020

Quantitative evaluation of coherency strains in Ni-12 at.% Al alloys has been performed by means of high resolution electron microscopy (HREM) and convergent beam electron diffraction (CBED) techniques. The alloy Ni-12 at.%Al is composed of two phases, the disordered fee Ni-Al solid solution and the coherent Ni3Al (γ') particles with an LI2 structure. The presence of γ' particles can impart excellent mechanical properties to these alloys. However these particles coarsen if subject to high temperature with an important reduction of mechanical properties. Coarsening of coherent particles in solid alloys is driven by the decrease of surface and elastic energies. The effect of surface energy is well understood but that of the elastic energy still requires experimental investigation. The source of elastic interaction between particles is the lattice parameter mismatch between particles and matrix. Evaluation of the elastic strain fields around particles can give some insight into the elastic interaction between particles and thus into the coarsening mechanism from an experimental viewpoint.
On-Line Semi-Automatic Measurement of Individual Crystal Orientations in Heavily Deformed Materials in the TEM
Authors: Zaefferer S
Published: July 2020

The measurement of individual crystal orientations in heavily deformed materials is of great importance especially for the study of recrystallization mechanisms. The electron backscattering diffraction (EBSD) technique which is frequently used nowadays in the SEM for these kind of studies has three important drawbacks: first, its spatial resolution is limited to about 0.5 μm, second, the sample deformation is limited to only about 60 %, and third, the dislocation microstructure cannot be observed. All these problems can be overcome using a micro beam diffraction technique in the TEM. Two techniques can be distinguished, the Kikuchi pattern technique and the spot pattern technique. With a spatial resolution of down to about 10 nm they arc well suited for orientation measurements in highly deformed material. Nevertheless, since spot patterns are less sensible to deformation the spot technique is the ultimate choice in the case a most highly deformed material. An automatic procedure for the evaluation of spot patterns has been developed and, together with the Kikuchi technique, implemented in a computer program for the on-line analysis of crystal orientations at the TEM. The new procedure and its applications to highly deformed materials is the subject of this presentation. Spot patterns are less sensitive to the sample deformation than Kikuchi patterns due to the differences in the diffraction geometry and due to the relaxation of the Bragg diffraction conditions for spot patterns.
Orientation Imaging Microscopy in the TEM
Authors: Baggethun P , Weiland H
Published: July 2020

There is a range of techniques now available for the study of crystallographic orientation in materials. Among these, Orientation Imaging Microscopy (OIM) for the SEM is being increasingly applied. This technique is, however, limited by the spatial resolution of the SEM (∼0.5 μm). TEM orientation measurements and imaging provides the necessary alternative to SEM measurements due to the much higher spatial resolution of the TEM (∼10 μm). In TEM crystal orientation measurements Kikuchi patterns are preferred over selected area spot patterns due to higher accuracy and spatial resolution. The earliest means of automation of TEM orientation measurements involved the use of digital scanners and beam deflection measurment for computerized semi-automatic indexing of the patterns. In recent years fully automatic on-line orientation determination has been developed. This has come about as a result of the advances in image processing for automatic indexing of backscatter Kikuchi patterns in the SEM, and the emergence of slow-scan CCD cameras with a large dynamic range.
Calculation of Absorptive Potentials Using Debye's Model of Lattice Dynamics
Authors: Anstis G R
Published: July 2020

To have an understanding of many imaging and diffraction effects relating to high-energy electrons it is essential to take into account the vibrations of the atoms of the solid being examined. Einstein's model of the vibrations takes the atoms to be independent oscillators. Debye's model includes the effects of correlated atomic motion and is more accurate in describing simple solids. Electrons which exchange energy with the solid through a change in the vibrational state of the solid are incoherent with respect to the incident electron wave and may be considered as being absorbed out of the incident wave field. Yoshioka and Kainuma showed how to calculate the components of the absorptive potential, which is imaginary rather than real, and pointed out that they depend on the direction of the incident wave. The components of the imaginary potential vgh  (im) are not simply a function of g-h, unlike those of the real potential describing elastic scattering. Here g and h represent vectors in reciprocal space. Using Debye's model and assuming that the speeds of the three components of acoustic waves in the solid are equal we find
New Applications of Electron Diffraction in Pharmaceutical Industry: Polymorph Determination of GP Ilb/IIIa Antagonist, Roxifiban, Using a Combination of Electron Diffraction and Synchrotron X-ray Powder Diffraction Techniques
Authors: Li Z G , Harlow R L , Foris C M , Li H , Ma P , Vickery R D , Maurin M B
Published: July 2020

Recently, it was reported that electron diffraction can be used to determine polymorphs in pharmaceutical industry [1]. The term polymorph refers to substances that have the same chemical formula but different crystal structures. Polymorphism has played an important role in drug development, production and litigation [2]. Synthesized and crystallized under different conditions, polymorphs may have different physical and chemical properties as well as bioavailabilities. The conventional techniques used to identify polymorphs.sometimes fail to differentiate definitively between two structurally similar polymorphs such as roxifiban, a very promising cardiovascular drug discovered recently at DuPont Pharmaceuticals [3,4]. Bulk and tapped densities of Form I and II, for example, were found to vary from 0.23 and 0.37 g/ml for Form I to 0.07 and 0.19 g/ml for Form II, respectively. These differences were of some concern given the low drug load in the solid dosage form. Unit cell parameters and atomic coordinates of crystalline polymorphs can routinely be determined by single-crystal xray diffraction techniques if suitably large crystals are available. However, many organic compounds tend to grow needle and plate-like crystals that never achieve a large enough volume for single-crystal studies. Such was the case with forms I and II of roxifiban.
Characterization and Representation of Crystallographic Texture Fields in Processed Alloys
Authors: Miller MP , Turner TJ , Sutliff JA
Published: July 2020

Deformation and thermal processing operations can produce structurally heterogeneous and anisotropic alloys. Thick, hot-rolled aluminum plate is an excellent example of such a material. Due to the plate size and thermomechanical conditions experienced by the plate during processing, significant gradients in material structure arise. These gradients are especially strong in the through-thickness or normal direction (ND) of the plate. In AA 7050, an aluminum alloy developed for thick plate applications, gradients in microporosity, grain morphology and crystallographic texture are known to exist. These features have been linked to material properties and performance measures in this alloy. Recent advances in high speed machining technology have made it possible to consider thick AA 7050 plate for an increasingly large number of airframe components. Because of its inherent heterogeneity, however, designing flight-critical components machined from AA 7050 plate will require one to quantify and mathematically represent the variation of the relevant microstructural gradients.
Development of BKD Hardware: Accomplishments and Opportunities
Authors: Schwarzer RA
Published: July 2020

Automated Crystal Orientation Measurement/Mapping (ACOM) as used in the SEM by unattended interpretation of Backscatter Kikuchi Patterns from bulk surfaces (BKP)* has become an invaluable new technique for the quantitative characterization of microstructure on a grain-specific level. The principal objectives are to relate grain orientations and misorientations directly to grain location in the specimen surface, to determine the character of misorientations and grain/phase boundary planes, and to calculate derived entities such as microtexture and anisotropic local materials properties. These quantities are commonly depicted in pseudo-colors on the scanning grid to form Crystal Orientation Maps (COM) or similar “images” of the microstructure. Stereological as well as orientation related data, as most sensitive indicators of the production process and use of a material, are readily available for basic research and quality control. The three-dimensional representation of microstructure by consecutive sectioning is still a challenge to enable the study of inhomogeneity beneath the surface and the three-dimensional connectivity of multiphase material. Dynamic experiments are a further promising application of this new technique in the SEM.
A Low Cost EBSD System: Implementation and Application
Authors: Pierron Xavier , Daghlian Charles , Baker Ian
Published: July 2020

Electron Back-Scatter Diffraction (EBSD) is a technique used for obtaining microtextural information from bulk samples in the scanning electron microscope (SEM). number of good commercial systems provide hardware and software to acquire and analyze the electron back scatter patterns (EBSP). The systems come with tools to visualize crystal orientation, and map grain and grain boundaries. However money is always in short supply, and for studies which do not require mapping, we have found it more economical to build our own EBSP system using readily available off-the-shelf components.

An EBSP's are formed by the intersection of the diffracted back scattered electrons with a phosphor screen placed in their path. We acquire this pattern by viewing the phosphor.screen through a view port with a CCD video camera which is configured for on-chip integration. On-chip integration allows the signal to be amplified without extensive electronic noise. We made a port cover for the right-hand port of the DSM-962 SEM on which a 2” diameter view window is fitted.
Grain Size Analysis Using Automated-EBSP
Authors: Sutliff J A
Published: July 2020

This work discusses using the automated Electron BackScatter Pattern (EBSP) technique of electron diffraction in the Scanning Electron Microscope (SEM) for measuring grain size in polycrystalline materials. A quantitative analysis of 2-D grain size from a standard metallographic section can be made in less than one hour using an automated-EBSP system on a traditional SEM and dedicated analysis software. Thus, the automated EBSP technique provides a useful and cost-effective way to determine grain size. A common measure used to describe grain size is mean intercept length (MIL) and the present discussion will be limited to determining MIL using EBSP.

Grain size analysis using optical microscopy is strongly influenced by sample preparation, which involves etching of the polished section to reveal boundaries. Boundaries that are to be avoided in determining MIL, such as sub-grain boundaries and twin boundaries, may be revealed and mistaken for random high angle boundaries.
Effects of Scan Rate and Electron Dose on the Secondary Electron Contrast of Liquids in Environmental SEM (ESEM)
Authors: Stokes DJ , Thiel BL , Donald AM
Published: July 2020

We report the effects of scan rate/electron dose on the secondary electron contrast in liquid systems, studied by Environmental Scanning Electron Microscopy (ESEM). Understanding the mechanisms for SE contrast is essential: previous observations of oil-water emulsions have revealed useful SE contrast between the dispersed and continuous phases, attributed to differences in the electronic structure of these molecular liquids. However, it has been found that large oil droplets for example, have a propensity to give SE contrast that can be inverted (relative to the continuous water phase) as a function of scan rate/electron dose, as shown in Figures 1 & 2. In the ‘grabbed’ image, Figure 1, the scan rate is a relatively rapid 2.1 frames/sec. and results in the expected image of oil droplets with lower SE signal intensity than the surrounding water phase. However, the intensity of the oil droplets changes dramatically when the scan rate is slowed, such that the droplets appear bright. Figure 2 shows the same region of sample as in Figure 1, but with image acquisition over 30 seconds. The same contrast inversion can occur at rapid scan rate if higher magnification is used. Effects such as this could result in ambiguous interpretation of ESEM images. However, useful information may be gathered as to the dielectric nature of the medium — a property related to molecular structure. We note that similar scan rate-dependent effects have been observed in ESEM studies of solid samples, although the mechanisms responsible have yet to be rigorously established.
Environmental SEM Study of Sodium Alginate Beads
Authors: Mansfield John , Eiselt Petra , Yeh Julia , Mooney David J
Published: July 2020

A variety of porous materials are used in a number of tissue-engineering applications such as cell transplantation and drug delivery. They provide a temporary scaffolding for a large cell mass, however they must have a fully interconnected pore structure. One such material is sodium alginate, a naturally derived polysaccharide which is isolated from seaweed. Sodium alginate can de dissolved in water to form a highly viscous solution that can be cross-linked in the presence of divalent cations (e.g., Ca2+) to form what is known a as hydrogels. We have developed a method for the fabrication of porous beads of sodium alginate and have attempted to measure the pore size, density and distribution in the beads. Characterization of the pore size and distribution is necessary to determine if the material is appropriate to promote cellular in-growth. The characterization procedures have been limited to conventional scanning electron microscopy (SEM) and mercury intrusion porosimetry. There has been some concern as to the potential introduction of artifacts (spatial distortion) during dehydration and sample preparation during these characterizations.
In-Situ Shape Transformation and Melting of Platinum Nanocrystals
Authors: Wang ZL , Petroski J , Green T , El-Sayed MA
Published: July 2020

The catalytic activity and selectivity of nanosize colloidal platinum (Pt) nanocrystals may depend strongly on their sizes and shapes. To determine the shape dependent catalytic behavior of Pt nanocrystals, two key steps are involved. First, shape controlled Pt nanocrystals must be synthesized at a high yield. Secondly, the passivation layer on the nanocrystal must be removed in order to measure the catalytic selectivity and activity while the particle shape is preserved. The former had been successfully demonstrated by us that platinum nanoparticles with a high percentage of cubic-, tetrahedral- and octahedral-like shapes, respectively, can be synthesized by a colloidal chemistry method [1,2]. The growth of the shape controlled Pt nanocrystal has been found to be the result of kinetic process [3]. To measure the shape dependent catalytic activity and selectivity of the Pt nanocrystals, the capping polymer must be removed. One method could be annealing the nanocrystals supported on a substrate for evaporating the capping polymer. Several questions, however, must be considered: (1) how high does the annealing temperature need to be to remove the capping polymer while the particle shape is still preserved? (2) to what temperature is the particle shape still stable? (3) is there a temperature induced shape transformation due to surface diffusion? (4) how high is the melting point of the Pt particles? and (5) what is the effect of substrate on nanoparticle melting? These questions have not only fundamental importance, but also practical impact on the catalysis applications of the particles because the chemical reaction may take place at a higher temperature.
Micro X-ray Fluorescence of Particles Using a Laboratory X-ray Source and Capillary Optics
Authors: Swider JR , Jach T , Steel E
Published: July 2020

Micro X-ray fluorescence (micro-XRF) is a useful nondestructive technique for multielement analysis of samples from a few hundred to a few micrometers in size. Micro-XRF is usually performed at synchrotron sources where element sensitivities are not compromised by micrometer spatial collimation of high flux beams. Ideally, micro-XRF would not have the burden of transporting samples to a synchrotron facility, but could be performed on a laboratory or portable scale. At the National Institute of Standards and Technology we are developing a micro-XRF system that combines a polycapillary optic with a standalone X-ray tube. This optic not only transmits the X-ray beam over 80 mm, but also focuses the beam to an area smaller than the unfocused beam size. The fine resolution combined with a high intensity produces a tool for laboratory scale micro-XRF analyses.

The X-ray focusing optic is a tapered, glass polycapillary optic. This optic, contained in an approximately 5 × 70 mm steel cylinder, transmits and focuses incoming X-rays to a spot 9.5 mm from the optic exit.
Fabrication of Organic Supramolecular Micro-Structures: Pre-Organization, Epitaxial Surface Recognition and Controlled Growth in a Model System of Biomineralization
Authors: Childs S , Hagen K , Apkarian R
Published: July 2020

In order to understand the systematic fabrication of hierarchical structures found in biominerals, the process nature uses in the biosynthesis of systems with complex morphology and precise internal molecular organization must be mimicked. The multi-component organic supramolecular system reported here is a kinetically controlled model that demonstrates the three stages of biomineralization: supramolecular pre-organization, interfacial molecular recognition, and cellular processing.

Three molecular components are used in this system: acetic acid (HOAc), benzene, and Kemp's Triacid (l,3,5-Trimethylcyclohexane-l,3,5-tricarboxylic acid or KTA). KTA and HOAc cocrystallize as hydrogen bonded aggregates of KTA dimers capped by four HOAc molecules. KTA and benzene co-crystallize with benzene acting as spacers between one dimensional hydrogen bonded rod-like structures of KTA. Growth of microcrystalline KTA/benzene was initiated by immersing single crystals of KTA/HOAc in 1 mL of benzene for 10-120 sec. The product was isolated on filter paper and mounted with carbon tape on an aluminum stub. The samples were coated with ∼10 nm of 60/40 Au/Pd prior to imaging at 15 kV in a DS-130/LaB6 SEM or at 5kV in a DS-130FE SEM.
Ultravibratomy Applied in Ultrathin Sectioning Results in Sections Without Distortions and Compression.
Authors: Studer Daniel , Gnagi Helmut
Published: July 2020

When resins are ultrathin sectioned they are compressed in the sectioning direction. The amount of compression depends very much on the sectioning angle on one hand, and on the properties of the resin on the other hand. Shortening of the sections in the sectioning direction is in the range of 5 to 35%. Even more compression occurs during cryosectioning of vitreous samples at very low temperatures (-170°C); the range was measured to be 30 to 60% (1).

To reduce these compression phenomena, there is basically only one approach possible. The sectioning angle has to be reduced as much as possible. In the past it was shown that by reducing the knife angle from 45° to 35°, a reduction of compression by appoximately one third was achieved (2). The problem with diamond knives is, that the smaller the knife angle, the more susceptible the cutting edge becomes. In practice angles smaller than 35° are not used because of this limitation.
High Pressure Freezing has Come of Age - but is it Mature?
Authors: McDonald Kent
Published: July 2020

It should be no secret by now that ultrarapid freezing is a superior method of specimen preparation for many biological EM projects, and that high pressure freezing is the most versatile of the freezing methods. While cryopreservation is not necessary for all EM studies, it is the method of choice for high resolution work and where “fixation artifacts”, such as distorted membranes, or extraction of the cytosol is a problem. It is true that the machines are expensive, and not always immediately available, but for some questions it is the appropriate technology to use. In the U.S., there are machines available for general use in the far West (Berkeley, CA), the upper Midwest (Madision, WI and Minneapolis, MN), and in the Northeast (Albany, NY). For locations of any of the other 8 machines around the country, interested users can call Technotrade, International at (603) 622-5011.

Current Status of High Pressure Freezing: A decade ago, Studer et al. wrote an article entitled: “High Pressure Freezing Comes of Age” that illustrated how high pressure freezing (HPF) had become a proven technology, useful for preserving ultrastructure with unmatched fidelity in cell types that had previously been difficult to fix well for electron microscopy (EM).
Using High Pressure Freezing and Freeze Substitution to Investigate Kinetochore Ultrastructure in Vetebrate Somatic Cells
Authors: McEwen BF , Hsieh CE , Barnard RM , Rieder C L
Published: July 2020

In vertebrate somatic cells, sister kinetochores attach chromosomes to the mitotic spindle by capturing microtubules (Mts) emanating from opposite spindle poles. Kinetochores are also required for chromosome alignment at the spindle equator, stabilizing kinetochore Mts, cell cycle control of anaphase onset, and poleward migration of sister chromatids during anaphase. Thus kinetochores play a critical role in the distribution of genetic information to daughter cells during cell division. Understanding the molecular mechanisms behind kinetochore function requires knowing how the molecular components are arranged relative to each other, and relative to the kinetochore Mts. Currently, however, our knowledge of kinetochore composition is incomplete, and until recently our knowledge of kinetochore ultrastructure was limited to the familiar trilamellar model derived from conventionally fixed and dehydrated specimens(Figures 1a&b).

Highly fibrous structures, such as the kinetochore, are particularly vulnerable to distortions caused by the chemical fixation and dehydration methods used in conventional specimen preparations. Such distortions can be largely avoided by using high pressure freezing and freeze substitution (HPF/FS).
Combined Cy3 / Nanogold Conjugates for ImmunocytoChemistry and in Situ Hybridization
Authors: Powell Richard D , Joshi Vishwas N , Halsey Carol M R , Hainfeld James F , Hacker Gerhard W , Hauser-Kronberger Cornelia , Muss Wolfgang H , Takvorian Peter M
Published: July 2020

Fluorescein and the 1.4 nm Nanogold® gold cluster label may be incorporated into a single Fab’ immunoprobe by separate cross-linking reactions, to give a probe which labels antigenic sites in a single step for correlative fluorescence and electron microscope visualization. These probes show high labeling density, labeling a pre-mRNA splicing factor in the HeLa cell nucleus; Microtubules were also densely labeled using fluorescence, other optical modalities, and electron microscopy; in a parallel experiment, a 5 nm colloidal gold probe gave only occasional labeling. We now describe Fab’ and streptavidin probes containing both Nanogold® and the fluorescent cyanine dye, Cy3.

F(ab’)2 Goat anti-Mouse IgG and F(ab’)2 goat anti-rabbit IgG fragments were reductively cleaved to Fab’ fragments using dithiothreitol (DTT) or mercaptoethylamine hydrochloride (MEA), which selectively reduce the F(ab’)2 hinge disulfide bonds, with 5 mm EDTA to prevent reoxidation. Fab’ fragments were isolated by gel filtration (coarse gel: GH25, Amicon) then labeled with Monomaleimido- Nanogold® which reacts site-specifically with thiols. Streptavidin was labeled using Mono- Sulfo-NHS-Nanogold® at pH 7.5. Nanogold® conjugates were isolated by gel filtration (Superose-12 column, Pharmacia), then reacted with excess Cy3 monofunctional NHS ester (labeling kit, Amersham Life Sciences) at pH 7.5; dual-labeled conjugates were isolated by gel filtration (Superose-12).
Non-Imaging Microscopies: Flow Cytometry as a Correlative Analytical Tool in the Quantification of Cell Structure, Autofluorescence, Fluorescent Probes and Cell Populations.
Authors: Smith R W
Published: July 2020

Non-imaging microscopy has developed somewhat independently of both traditional light microscopy and laser confocal microscopy. Flow cytometry is the chief commercial and research technology among these microscopies, and, like other nonimaging detection systems, developed around the theme of automation in clinical laboratory medicine. It is an important correlative or parallel microscopy to several image forming microscopical methods. Cell sorting is an important option as well.

The basic structure of the flow cytometer certainly parallels light, laser and electron microscopes. The flow cytometer has a light source, a set of adjustable optics to focus the beam on the specimen, objective optics to collect the light and direct it to appropriate sensors, and the sensors themselves. A real image is not formed because the sensors are not in an even plane with the projection, such as provided by the retina in light microscopy or an image plane or film plate in electron microscopy, and the objective optics may not focus in the image plane.

While early flow cytometers were developed primarily for the automatic counting of cells and particles, modern instruments offer particular advantages for the analysis of fluorescence, fluorescent chemicals and probes and cellular auto fluorescence.
Immunohistochemical and Morphometric Characterization of Blood Vessels in Brain Metastasis in Nude Mice
Authors: Bucana C D , Yano S , Reynolds D , Dunner K , Fidler I J
Published: July 2020

This study was conducted to compare the immunohistochemical and morphometric characteristics of blood vessels in brain metastasis with blood vessels of the adjacent uninvolved brain tissue. This is based on the hypothesis that new vessels formed in the tumor express antigens that are not expressed in blood vessels of the adult brain parenchyma. Thus, a panel of antibodies known to react with mouse endothelial cells at various stages of differentiation or stimulation was tested on frozen sections of experimental brain metastasis. Intratumoral microvessel density which has been reported to reflect the intensity of tumor angiogenesis was inapplicable to experimental brain metastasis therefore other parameters were measured.

Brain metastasis was produced in nude mice following intracarotid injection of tumor cells. Three human tumors and three murine tumors were injected into the carotid artery of nude mice. The animals were sacrificed when they were moribund, the brains were embedded in OCT and frozen in liquid nitrogen. Some animals were injected with bromodeoxyuridine (BrdU) 1 h before they were necropsied. Immunohistochemistry was performed using antibodies directed to the following antigens: CD31, CD34, MECA-32, endoglin, ICAM-1, ICAM-2, and BrdU. Antibodies to leukocyte antigens, F4/80 and CD3 were also tested to determine the amount of host cells infiltrating the tumors. SEM of immunogold labeled preparations determined the cellular localization of some antigens.
A Compilation of Biological SEM Sample Prepartion Techniques for Application to Outreach Programs
Authors: Smith NR , Duarte E , Morgan C , Quinta RA
Published: July 2020

A partnership between California State University, Hayward and Ohlone College, Fremont, California resulted in a program to introduce undergraduate students to scanning electron microscopy (SEM) sample preparation procedures. Ten students enrolled in a biology major's course at the Ohlone Community College are selected each semester to participate in the program. In addition to these students, ten others from a Basic Skills Enhancement program for underrepresented students participate through a short course offered during the summer. The program, in effect for two years, resulted in the compilation of a laboratory manual describing basic sample preparation techniques that are appropriate for an outreach program. We select samples that are simple to prepare yet yield results that are germane to a biology student's curriculum. A selection of plants, pollen grains, bacteria, fungi, yeast, Drosophilia melanogaster, and various other invertebrates are typical samples that lend themselves to an outreach program that emphasizes biological concepts. Initially our program required the Ohlone College students to come to the Hayward campus to prepare their samples. External funding has allowed us to purchase sample preparation equipment for the community college.
An Introduction Electronic Documentation Preparation and Submission for Future Microscopy and Microanalysis Meetings.
Authors: Mansfield John F
Published: July 2020

Since the introduction of personal computers in the early 1980s, most documents and manuscripts have been prepared from within a word processing program on such a computer. Indeed, most documents on personal computers are created on a limited number of word processing packages that have come to dominate the market. Most of the data acquisition that attendees of Microscopy and Microanalysis currently perform is digital, i.e. directly into a personal computer or desktop workstation. It is frequently the case that images, spectra and diffraction patterns are only committed to paper when they are dispatched for publication. With the advent of the World Wide Web in 1994, and its subsequent explosive growth, entirely electronic publishing has become possible. It is possible to envisage the day when most publications will be available solely electronically and material will be only printed out occasionally by the reader.

While there are a growing number of journals that are only available electronically, entirely paperless publication is not yet the norm and there are no definite plans, as yet, to publish the proceedings of the Microscopy and Microanalysis meetings solely in electronic format. However, there are a number of advantages to applying some of these emerging technologies in the production of the future proceedings. Electronic submission of abstracts is one advance that is being considered by the organizers of the meetings scheduled for the early 2000s. The National Science Foundation now receives almost all proposals electronically. There are several reasons for moving to electronic submission. The first is that proofing and correcting the abstracts would then be straightforward.
Development of Electron Probe Instrumentation During those Early Days When Professor Castatng Visited Japan
Authors: Shimizu R
Published: July 2020

In May of 1955 Professor Shinoda introduced the development of the electron probe microanalyzer (EPMA) in a review article published by Oyobutsuri (the Applied Physics journal written in Japanese), which showed a schematic diagram of an EPMA system. That paper, published in the most popular journal in Japan, was very probably the first paper which drew the attention of the people involved in the field of material science, in particular, the field of metallurgy, who were especially interested in EPMA. That paper stimulated the development of EPMA in Japan.

In 1957, the funding provided by the Grant-in-Aid for Developmental Research to the university research groups headed by Profs. Akutagawa, Gokyuu, and Abe at the University of Tokyo was used, in a cooperation with the Hitachi group headed by Drs. Tadano and Watanabe, to develop the EPMA in Japan. Their research results led to the funding of a 2 year Grant-in-Aid for Cooperative Research project (April 1960 to March 1962) called “The Study of X-ray Microanalyzer”, which was chaired by Prof. Sakaki and consisted of 37 members from various universities, national institutes and industries. Prof. Shinoda, who became the Chairman of that project in April of 1962, led that group for another year until March of 1963.

It was just after the start of the Cooperative Research project, in September of 1960, that Professor Castaing visited Japan and gave several talks as a representative of the French Mission Culturelle. Professor Castaing gave a talk at the Hitachi Central Research Laboratory on the 19th of September, another talk at the Nagoya University on the 24th of September, and also a talk at Osaka University on the 28th of September. During his stay in Japan from September 18th to October 4th he talked about his work on EPMA a total of six times by also giving two informal presentations. The visit of Professor Castaing gave a great push forward for the commercial development of EPMA instruments in Japan.
Application of the Electron Probe Microanalyzer to the Analysis of Planetary and Geological Materials: a Historical Perspective.
Authors: Keil Klaus
Published: July 2020

Castaing first presented his idea to use secondary X-rays excited by a focused electron beam from a polished solid sample for microanalysis in 1949 at the First European Regional Conference on Electron Microscopy in Delft, Netherlands. As part of his dissertation, he then not only built the first electron probe microanalyzer (EPM), but also established many of the theoretical and analytical principles of the technique. This technique offered enormous analytical advantages to earth scientists over other analytical methods available at the time. For example, it allows qualitative and quantitative analysis of individual mineral grains a few microns in diameter; mineral grains can be viewed during analysis, thus ensuring accurate correlation between composition and grain morphology; for most purposes, the method is non-destructive; in situ analysis of minerals in polished thin sections results in retention of textural relationships among coexisting minerals; because of the small excitation volume, the technique is ideally suited for the study of zoned minerals, minute inclusions, exsolution lamellae, etc.; and once suitable standards are prepared and correction procedures are established, a large number of quantitative analyses can be obtained in a comparatively short time.
Analysis of Metallic Pigments Used in 19th Century Japanese Prints
Authors: Hashimoto RY , Menon ESK , Fiorillo J
Published: July 2020

Japanese color woodblock prints ("ukiyo-e") from the Edo (1615-1868) and Meiji periods (1868- 1912) are among the most celebrated examples of color printmaking in the world. Full-color prints became technically and commercially viable around 1765. Traditional ukiyo-e colorants were watersoluble, uniform, translucent, organic (vegetal) and inorganic pigments of very small particle size. (Synthetic colorants were also introduced from the West in the 19th C, probably beginning with "Prussian blue" in the 1820s.) A pigment was applied with a brush to a color block, and then rice flour paste was mixed with the pigment to thicken it, facilitate control and rubbing into the paper, improve the uniformity of the colorant, and avoid a dry or granular texture. The dampened paper, sized with cooked bovine skins and alum, was then placed on the block (aligning with registration marks cut into the blocks). The colorants were then pressed into the paper by rubbing a bamboo pad against the back of the paper so that the colors were absorbed on the front surface.
SEM and EDS Characterization of Palladium Cathodes After Electrolysis in Light and Heavy Water
Authors: Silver D , Dash J
Published: July 2020

Studies of Pd foil cathodes have indicated that when electrolyzed for long times in electrolytes containing both deuterium and hydrogen ions along with sulfuric acid, the cathodes undergo compositional, topographical, evolutionary, and isotopic changes. The results reported here describe the changes which are produced in Pd cathodes after only a few minutes of electrolysis.

In June 1993 a cold-rolled, Pd (AESAR lot #12E06) cathode of 40μm thickness was submerged at one end into an electrolyte containing 20 ml D2O and 3.5 ml H2SO4 and electrolyzed for six minutes at about 0.6 A/cm2 and 3.65 V. An identical Pd cathode (cut from the same strip) was submerged at one end into an electrolyte containing 20 ml H2O and 3.5 H2SO4 and electrolyzed for six minutes using 0.6 A/cm2 and 4.11 V. A Pt foil acted as the anode in each case. The two cells were connected in series. An ionic current flowed between the electrodes for each system as the voltages were applied.
Simulation of Energy Deposition in E-Beam Irradiated Polymers
Authors: Horny Paula , Gauvin Raynald , Hovington Pierre , Besner Simon
Published: July 2020

Introduction

Radiation curing of polymers, by UV light or E-beam, is of growing interest in the state-of-the-art industry. Radiation curing is solvent free and leads to important energy and money savings. Improved materials characteristics, better control of doses and more accurate application allow radiation curing to take a big part of the surface coating industry and, for the last ten years, the polymeric and microelectronics (lithography) industry. But behaviors of polymers under radiant source is often empirically characterized. In this abstract, it is proposed a way to obtain accurate energy distribution from Monte Carlo simulations. For bulk or thin polymeric films, it is therefore essential to simulate energy distribution, in order to foresee what happens in the sample.

Results

CASINO is a single scattering Monte Carlo Simulation of electroN trajectory in sO lid -particularly designed for low energy beam interaction in a bulk and thin foil.
Trace Element Mapping of Minerals and Materials by Electron Microprobe
Authors: Fournelle J , Davidson C , Spear F , Kohn M , Guo H
Published: July 2020

A strength of the modern electron microprobe is its ability to provide 2D compositional information about materials. These images give the ability to observe features that might otherwise pass unseen. Elements at the trace element level are generally ignored due to the high detection limits imposed by mapping under “standard” EMP conditions.

Trace element mapping requires beam regulation at high (e.g. 300 nA) to very high (e.g. 3 μA) faraday cup currents, reliable beam and stage control, and suitable samples and mounting media. The ability to operate at high accelerating voltage to maximize Pk2/Bkg is desirable (Robinson and Graham, 1992), although we have encountered column difficulties above 25-30 kV.

We are mapping trace and minor elements including Y, Sc, P, Cr, Mn, Ca, in garnets. Fig. 1 shows Y, Sc and Cr maps (Spear and Kohn, 1996; Kohn, Spear and Valley, 1997), and Fig. 2 Y and Sc maps (Cameron, unpub. data), produced with a Cameca SX51.
Integration of a Monochromator in the Field Emission STEM
Authors: Mookb HW , Batsona PE
Published: July 2020

It would be very desirable to obtain EELS at 0. l-0.2eV resolution for bandstructure studies at interfaces and defects. [1,2] It has been possible to build spectrometers that perform in this energy range, but it has been difficult to utilize this resolution, because the energy width of the cold field emission source is about 0.3-0.4 eV for the currents needed to do practical microscopy. [3] Numerical methods have been used to sharpen the spectra, showing unambiguously that EELS spectra would benefit greatly if a higher resolution source were available. [4,5]

This situation has led one of us (H.W. Mook) to investigate electron monochromator optical designs which would be compatible with the high brightness and current required by the STEM. [6] This work produced a 4cm long monochromator that can be integrated into the field emission source. As shown in Fig. 1, the monochromator optics includes a field lens formed by deceleration of the electron beam from the 3 KeV extraction energy to about 350 eV inside the monochromator, a short Wien Filter velocity dispersive field, 150nm wide Si energy selecting slits, and an acceleration field lens at the monochromator exit.
The Electronic Band -Gap of Polycrystalline Diamond and Tetrahedral Amorphous Carbon by EELS in a STEM.
Authors: Papworth AJ , Kiely CJ , Amaratunga GAJ
Published: July 2020

Good quality polycrystalline diamond is transparent and has an optical band-gap very close to that of single crystal diamond, 5.5 eV. Tetrahedral amorphous carbon (ta-C) is a form of amorphous carbon which can have up to 90 % sp3 type bonds. It is the form of amorphous carbon, which is closest to having a true diamond-like structure. The optical band-gap of ta-C is however very different from that of polycrystalline diamond, typically in the range 2-3 eV. This difference in the optical bandgap has been ascribed to the electronic states formed by the residual graphitic bonding. The π − π* states at the graphitic sites effectively form tail states on the valance and conduction band edges created by the diamond-like bonding. These tail states extend deep into the band-gap, which would exist if there were only (100 %) diamond-like bonds. The poor electronic properties obtained thus far for ta-C are now accepted as being associated with localised conduction in the π − π* tail states.
Insights into the Electronic Structure of Ceramics Through Quantitative Analysis of Valence Electron Energy-Loss Spectroscopy (VEELS)
Authors: Müllejans Harald , H. French Roger
Published: July 2020

The electronic structure of ceramics can be extracted quantitatively from the valence electron energy-loss spectroscopy (VEELS) of transitions between the valence and conduction bands. We obtained VEEL spectra of several ceramics (FIG. 1) with a VG HB501 dedicated STEM equipped with Gatan PEELS. Improved data acquisition and new methods of data analysis allowed us to treat the data fully quantitatively. The reliable and accurate removal of the zero loss peak was crucial because intensities at energy losses just above the band gap of the ceramic material have a large influence on the results. An asymmetric Pearson VII function was fitted into the zero loss peak up to an energy loss for which no transitions are expected (an energy smaller than the band gap of the ceramic) and then extrapolated to higher energies. This limits the analysis to non-metallic materials, exhibiting non-zero band gap energies. We are currently developing methods to perform the analysis on metallic materials, using ellipsometric data in the visible and extrapolate the energy-loss function to 0 eV and thereby remove the need for the no transition energy.
Stem Without Spherical Aberration
Authors: Krivanek OL , Dellby N , Lupini AR
Published: July 2020

Even though two generations of electron microscopists have come to accept that the resolution of their instruments is limited by spherical aberration, three different aberration correctors showing that the aberration can be overcome have recently been built [1-3]. One of these correctors was developed by us specifically for forming small electron probes in a dedicated scanning transmission electron microscope (STEM) [3, 4]. It promises to revolutionize the way STEM instruments are built and the types of problems that they are applied to.

As was the case with the Berlin Wall, when a barrier that was once thought immovable finally crumbles, many of the consequences can be quite unexpected. For STEM, the removal of spherical aberration (Cs) as the main resolution limit is likely to lead to a new paradigm in which:

1) The resolution at a given operating voltage will improve by about 3x relative to today's best. When Cs can be adjusted arbitrarily in a STEM being used for microanalysis or dark field imaging, defocus and Cs are set to values that optimally oppose the effect of the 5th-order spherical aberration C5.
“Y Contrast” of Single Shell Carbon Nanotubes: Determination Of Young’s Modulus by Observing Thermal Vibrations
Authors: Treacy MMJ , Krishnan A , Dujardin E , Yianilos PN , Ebbesen TW
Published: July 2020

Single shell carbon nanotubes are members of the Fullerene family of carbon molecules. Typically, single shell carbon nanotubes measure about 0.7 — 3 nm in diameter and are usually several microns in length. Structurally, they can be thought of as narrow graphite sheets that have been bent around the long axis and joined at opposite edges to form long seamless hollow shells of carbon. Typically, a hemispheroidal cap that contains exactly six 5-rings terminates each end, as shown in Figure 1.

Graphite is known to have an in-plane elastic modulus of ∼1 TPa, one of the highest values known. Consequently, it is expected that single shell nanotubes should be very stiff — a fact that makes them potentially useful in fiber reinforced composites. However, because of their small size, it is impractical to measure their stiffness directly by conventional mechanical means. Recently, we demonstrated that thermal vibrations in freestanding multiwalled nanotubes could be used to estimate their stiffness [1].