bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron spectroscopic imaging and analysis of calcium ions during the first 24h of the interaction of Trypanosoma cruzi heart muscle cell
Authors: Nazareth Meirelles Maria , Claudia Pereira Miriam 
Published: June 2020

Several processes are controlled by the intracellular level of calcium ions. It is generally accepted that calcium ions play an important role contraction-relaxation cycle of muscle cells. Chagas 'disease is an endemic disease in South America caused by T. cruzi where a parasite - induced destruction of heart muscle occurs leading to heart failure, cardiac blockage and arrythmias.In order to study the role of calcium ions during the interaction of T. cruzi - host cells, primary cultures of heart muscle cells (HMC) obtained from dissociation of heart mice embryos were infected with trypomastigotes forms of T. cruzi for 24h (1). The cells were processed with protocols that include in the fixation step the presence of 2.5 to 10mM of CaC12 and in the post fixation the addition of 0.8 potassium ferrocyanide in 2 osmium tetroxide plus 2.5mM CaC12 (2.3).The electron spectroscopic image (ESI) of ultrathin and unstained specimens were performed with a Zeiss EM 902 equipped with an integrated imaging electron energy spectrometer that eliminates aberrations and contrast losses and produces elementspecific images.
Quantitative EDS analysis in the SEM applying the XPP procedure
Authors: Pouchou Jean-Louis , Pichoir Françoise 
Published: June 2020

Extensive work has been done during the last decade to develop new models able to improve the performance of data reduction procedures 1n quantitative x-ray microanalysis. Some of them are now successfully used as routine tools in microprobe work, and allow to analyze accurately light and ultra-light elements and to characterize layered specimens.In the field of analytical scanning electron microscopy (SEM) using energy dispersive spectrometers (EDS), it seems that less attention has been paid to the effective improvement of the quantitation processes. Although EDS systems have unavoidable limitations due to their lower peak-to-background ratio and poorer resolution, the authors have the feeling that the quantitative results can be significantly improved by use of more reliable models taking properly into account the specific instrumental and experimental conditions.With this aim in view, our first contribution has been to implement our recently developed XPP model and associated routines (mass absorption coefficients, efficiency of the Quantum window) into the KEVEX Delta system.
Computer programs for the calculation of x-ray intensities emitted by elements in multi-layer structures
Authors: Bastin G.F. , Heijligers H.J.M. , Dijkstra J.M. 
Published: June 2020

For the calculation of X-ray intensities emitted by elements present in multi-layer systems it is vital to have an accurate knowledge of the x-ray ionization vs. mass-depth (ϕ(ρz)) curves as a function of accelerating voltage and atomic number of films and substrate. Once this knowledge is available the way is open to the analysis of thin films in which both the thicknesses as well as the compositions can usually be determined simultaneously.Our bulk matrix correction “PROZA” with its proven excellent performance for a wide variety of applications (e.g., ultra-light element analysis, extremes in accelerating voltage) has been used as the basis for the development of the software package discussed here. The PROZA program is based on our own modifications of the surface-centred Gaussian ϕ(ρz) model, originally introduced by Packwood and Brown. For its extension towards thin film applications it is required to know how the 4 Gaussian parameters α, β, γ and ϕ(o) for each element in each of the films are affected by the film thickness and the presence of other layers and the substrate.
Microanalysis of Asbestos Fibers by Ft-IR Microscopy
Authors: Reffner John A. , Wihlborg William T. 
Published: June 2020

The identification of asbestos fibers in bulk or airborne samples can be made by Fourier transform infrared (FT-IR) microscopy. Since asbestos fibers have been shown to be a health hazard, it is important to identify their presence in environmental samples. Asbestos fibers require both chemical and morphological data for their identification. This FT-IR microscopical method uses light microscopy for morphological and infrared spectroscopy for chemical identity of microscopic fibers. For the six minerals defined by the EPA as asbestos, the infrared spectral analysis can be made on the same sample preparations that are used for polarized light microscopy(PLM) or phase contrast microscopy (PCM) counting. In this study, the detection limit for asbestos fibers in airborne samples was 2 × 20μm (˜˜240pg).The infrared spectra of microscopic fiber bundles of standard asbestos minerals were obtained using an IRμS™ infrared microspectrometer. Spectra were collected within the range of 4000 to 600 cm-1 (2.4 to 16.7 μm), at a spectral resolution of either 2 or 4 cm-1.
Low-temperature Scanning Electron Microscopy and Physical-Chemical investigations of leaf surface characteristics
Authors: Guggenheim R. , Zuberbühler E. , Düggelin M. , Harr J. 
Published: June 2020

Plant protection agents (often incorrectly referred to as ‘pesticides’) mostly are targeted at plant surfaces either to protect them against pathogens and parasites or to destroy the treated plants in the case of herbicides. Many times, more than one species of plants are involved, that respond differently to such applications.In any of the cases cited, a thorough knowledge of the leaf surface characteristics may help to explain desired or undesirable effects. Also the wetting properties of a spray applied to plants will likely influence the performance of the active ingredient involved. It is obvious that only the use of a whole array of different methods will allow an interpretation or a prediction of effects caused by the application of plant protection sprays.To get well preserved epicuticular wax structures of leaf surfaces we used low-temperature scanning electron microscopy (LTSEM). Fresh cut samples were immediatly frozen in liquid nitrogen, transferred into a Balzers SCU 020 cryopreparation unit attached to an SEM Cambridge Mk II A.
Intensity Sensitivity of RHEED
Authors: Ma Yiqun , Bonevich John , Marks Lourie D. 
Published: June 2020

It is well recognized that RHEED patterns are very rich in information. However, due to the lack of a suitable dynamical theory for the interpretation of these patterns obtained from arbitrary surfaces, one important part of the information-the intensities of these patterns (instead of individual spot), has not been used for surface analysis. With newly developed EPMO method (Edge Patching method in Multislice-Only mode), dynamical simulations of RHEED patterns for arbitrary surfaces have become possible. The results of the simulations show that the intensities of RHEED patterns are highly sensitive to various surface structures, such as surface reconstruction, adsorption, surface relaxation, surface absorption and surface steps ect..Fig.1 shows the simulated RHEED patterns using the EPMO method for the 2×1 missing row reconstruction (a) and the 2×1 oxygen chemisorption (b) on the Au(001) surface and [010] zone. The incident energy is 100keV and the incident angle is 30mRad. The intensities of fractional spots corresponding the 2×1 oxygen chemisorption in (b) are perceivably weaker than those corresponding to the 2×1 reconstruction in (a), since the oxygen is a weak scatter, compared to the gold.
Applications of High-Resolution X-ray Mapping
Authors: Garratt-Reed Anthony J. 
Published: June 2020

It has been well established that x-ray imaging (mapping) of samples at high magnification in a field-emission analytical electron microscope is a viable technique when some form of correction is employed to compensate for the unavoidable image drift which occurs during the somewhat extended acquisition time of the images. The technique is only of practical use, however, if the time spent in acquiring the image results in data which would not otherwise have been obtained. It is the purpose of this paper to present examples where high-resolution mapping did provide data which was unique and essential to solve the problems under investigation.All experiments were performed in a VG Microscopes HB5 STEM, with a field-emission gun operating at 100kV. For most experiments, the probe size was of the order of 2 nm, and the probe current was 0.2-0.4 nA. The x-ray detector was a Link Analytical LZ5 windowless energydispersive x-ray spectrometer with a resolution of 137eV at 5.9kV, subtending a solid angle of 0.078Sr at the sample.
On-line measurement of specimen thickness by Convergent Beam Electron Diffraction
Authors: Otten Max T. 
Published: June 2020

Convergent Beam Electron Diffraction (CBED) thickness measurement is the easiest and most accurate way of determining the thickness of crystalline materials. The method was described by Kelly et al. The specimen thickness can be calculated from a few measurements on a recorded diffraction pattern in a matter of minutes (by hand) or seconds (by a computer program).For thickness measurement a CBED pattern is needed that contains a two-beam diffracting condition, with a dark Kikuchi line going through the centre of the Bright-Field disc and the corresponding bright Kikuchi line through the centre of a Dark-Field disc. Parallel to the bright Kikuchi line, the Dark-Field disc contains a number of fringes (Fig. 1) whose distance from the Kikuchi line varies with specimen thickness. The data needed for a measurement are the electron wavelength, the d-spacing dhkl of the diffraction used, the distance 2θB between the Bright-Field disc and Dark-Field disc in the CBED pattern, and the distances Δθi between the dark thickness fringes and the bright Kikuchi line in the Dark-Field disc (Fig. 2).
TEM contribution to solve the crystal structure of Sr5Ir3O11
Authors: Li Z. G. , Harlow R.L. , Marshall WJ. , Crawford M.K. , Subramanian M.A. 
Published: June 2020

X-ray diffraction plays a dominant role in the crystal structure determinations. Typically, diffraction data of a selected "single" crystal is first collected by a diffractometer, and then the crystal structure can be solved and refined. The quality of the structure determination is measured by the crystallographic residual value R. If the R value is reasonably small, the structural model is assumed to be correct. Usually, models found by x-ray diffraction do describe real structures and these can be confirmed by other techniques. We report here an unusual case, a plausible structural model which yielded a low R value from data collected on a crystal that was NOT "single": the structure derived from the "single" crystal x-ray diffraction data is completely bogus. TEM played an important role in solving this problem.In the context of high-temperature superconductivity, we have recently studied Ir+4 containing layered oxides in the SrO-IrO2 system. Sr2lrO4 has a K2NiF4-type structure with a rotational distortion (see fig. la).
Structure of high hardness cathodic-arc deposited carbon
Authors: Callahan D. L. , McAdams S. D. , Anders S. , Anders A. , Brown I.G. , Bhatia C. S. 
Published: June 2020

Carbon films exhibiting a peak hardness of 59 GPa have been produced using pulsebiased cathodic-arc deposition. This value is much greater than that expected of an amorphous "diamond-like" carbon (die) film and is well within the hardness range of chemically vapor-deposited diamond. Furthermore, this peak hardness is observed at an indentation depth of approximately 50 nm and not on the upper surface of the film. A structural analysis by transmission electron microscopy (TEM) has been conducted in order to explain these mechanical phenomena.Details of the sputtering apparatus are described elsewhere. Films for this study were deposited on silicon using a two-step process in which a thin layer, approximately 10 nm, was first deposited at a relatively high substrate bias (~2 kV) followed by growth of the majority of the film at a lower bias (~200 V). Plan-view examination of carbon films revealed both uniformly amorphous regions and extensive nanocrystalline phase regions.
Atomic resolution in energy-loss images: fact or artefact?
Authors: Otten Max T. 
Published: June 2020

Since the introduction of energy-filtered imaging, the ultimate resolution has been a point of debate. Berger and Kohl[1] concluded that resolution is limited to ~1 nm. In contrast, one group of investigators[2,3] has argued that atomic resolution can be achieved. The conclusions from the latter group have been questioned previously [4]. In order to provide more insight into the origin of the fine detail in some energy-loss images, a number of experiments have been performed to try and resolve this issue.The main issue of the high-resolution detail in energy-loss images (i.e., images from electrons that have lost an amount of energy) is whether it comes from elastic or to inelastic scattering. In the former case, a combination of elastic scattering and inelastic scattering, the high-resolution energy-loss image is an artefact. In the latter case, inelastic scattering only, it would be real.On the basis of theory energy-loss images are unlikely to achieve atomic resolution.
Quantitative compositional mapping of InxGa1-XAs/GaAs quantum wells by annular dark field imaging
Authors: Hillyard S. , Chen Y.-P. , Schaff W.J. , Eastman L.F. , Silcox J. 
Published: June 2020

Annular dark field imaging in the scanning transmission electron microscope (STEM) exhibits both high resolution and Z-contrast. It is intrinsically quantitative since image data can be recorded directly from linear detectors into digital memory. Annular dark field imaging has been used, along with energy filtered imaging to correct for sample thickness variation, to map out the In concentration in InxGa1-xAs quantum wells with near atomic resolution and sensitivity. This approach is similar to “chemical lattice imaging”, which maps out composition variation using a conventional transmission electron microscope image and a vector pattern recognition algorithm.The quantum wells were grown by molecular-beam epitaxy (MBE). Figure 1 shows a typical high resolution annular dark field image of a 50 Å wide nominal In0.3Ga0.7As/GaAs quantum well. The linescan in figure 2 gives the actual numbers making up the image. Barring contaminants and lattice imperfections, the change in intensity with position is caused by two things: variation of In concentration and thickness.
Compositional separation in CoCrTa thin film as observed using a TEM with an imaging filter
Authors: Kimoto K. , Yahisa Y. , Hirano T. , Usami K. , Narishige S. 
Published: June 2020

Cobalt chromium alloys are current longitudinal high-density recording media. Compositional features in the cobalt chromium thin films directly affect the magnetic and recording properties. Elemental analyses of the films have been performed by several methods, however, topological nature and crystallographic information are still ill-defined because of limitations in these methods.In the present study, elemental mapping of cobalt and chromium in a CoCrTa thin film has been quantitatively performed using a transmission electron microscope (TEM) with an imaging filter.A chromium underlayer (75nm thick) and a CoCrTa magnetic layer (27nm thick) were deposited on a Ni-P plated Al-Mg alloy substrate using direct current magnetron sputtering at a substrate temperature of 270°C. Target contents for sputtering of the CoCrTa film are shown in Table I. Energy-filtered images and electron energy loss spectra (EELS) were acquired using a TEM (Hitachi, HF-2000) equipped with an imaging filter (Gatan, imaging filter model 678). Because of the high brightness of a field emission gun, this system allows a small collection semiangle (4.4 mrad) and a narrow energy window (20-30 eV) for imaging.
Scanning EM in very high electric fields near field ion/emission specimens
Authors: Larson David J. , Camus Patrick P. , Kelly Thomas F. 
Published: June 2020

An atom probe field ion microscope (APFIM) has been constructed inside a NORAN Instruments Automated Digital Electron Microscope (ADEM). The ADEM is a scanning electron microscope (SEM) with a field emission source and a very large vacuum chamber. The APFIM has positive and negative high voltage capability and uses a microchannel-plate/phosphor screen assembly as an imaging and single-ion detector. The APFIM specimen can be cooled by a cryogenic refrigerator. The motivation for this study was the need to deliver an electron beam to the apex of an APFIM specimen while a high field is applied. The beam will be used to thermally pulse the field evaporation rate. The expected field-induced image shift and distortion has been studied previously in a transmission EM with a liquid metal field emission source as a specimen.Fig. 1 shows the interior of the instrument. Computer simulations were done for electron trajectories with negative and positive voltages applied to the emitter based on a simple paraboloidal electric field model described previously.
Problems in interpreting sub-Å-resolution images studied by simulated evolution based digital image matching
Authors: Möbus G. , Dehm G. , Gutekunst G. , Rühle M. 
Published: June 2020

1. Introduction:Experimentally determined CTF-data caused predictions that atomic resolution microscopy (JEM ARM1250) of sapphire should become possible with single atomic columns resolved (Fig. 1). The smallest projected bond-length (ca. 0.85 Å) lies beyond the point-resolution of 1.05 Å but within the information limit of this instrument (around 0.85 Å). After extensive trials such images could not be verified experimentally. Instead, images like Fig. 3 b typically appear, containing still high frequencies but different from predictions.2. Ideal and realistic image simulations:Reasons for this deviations have been examined following with special respect to sub-Å-resolution, including specimen tilt, beam tilt, achromatic anisotropic damping (MTF, vibration, drift), non-ideal columns and amorphous contamination. The stepwise EMS-contrast generation from the crystal single slice over the specimen exit plane into the image plane is compared in Fig. 1 (ideal alignment) and Fig. 2 (realistic simulation). Predominant factors lie in specimen misalignment or other disturbancies (e.g. strain fields) during multislice followed by trade-off effects during fitting of imaging parameters and achromatic damping. The single slice potential is of less influence in the present case.
Association of gamma-glutamyl transpeptidase (γ-GTP) positive cells with tube-forming structures in rat brain endothelial cell cultures: a bright field and laser confocal microscopy study
Authors: De Bault L.E. , Wang B.L. , Grammas P. , Ringer D.P. , Kong J. 
Published: June 2020

Gamma-glutamyl transpeptidase (γ-GTP), an enzyme purported to regulate amino acid transport, is expressed at high levels in blood-brain-barrier (BBB) capillary endothelium, but is a property that is variably expressed in cell culture. The ability of endothelial cells to form capillary-like tubes under different culture conditions has been reported by several investigators. In this study, a rat cerebral resistance vessel endothelial cell strain (RV-150 ECT) , that spontaneously forms cellular aggregates and connecting tubes, has been shown to contain a subpopulation of γ-GTP positive cells, was evaluated for the spatial relationship between γ-GTP and its mRNA, and the tube-forming structures in culture.Cells were grown on coverslips and fixed in acetone for enzymecytochemistry or in 3% paraformaldehyde and 0.5% glutaraldehyde in PBS pH 7.4 for immunocytochemistry and in situ transcription (IST), respectively. The enzyme substrate/acceptor were γ-glutamyl-4-methoxy-2-naphthyl-amine and glycylglycine. The primary antibody was affinity purified goat anti-γ-GTP IgG. The primers for the IST were 25-nt oligonucleotides complementary to γ-GTP mRNA. After the primers were hybridized to the mRNA the mRNA was transcribed in situ in a mixture of dNTPs containing DIG-labeled dUTP and reverse transcriptase.
Ultrastructure of fat body trophocytes in the life stages of Dermacentor variabilis (Say)
Authors: Coons Lewis B. , Lamoreaux William , Rosell-Davis Rosemarie , Starr-Spires Linda 
Published: June 2020

The American dog tick, Dermacentor variabilis (Say), has three life stages: larva, nymph, and adult. Each stage requires a blood meal to molt to the next stage or to reproduce and each stage has a fat body. A light microscopic study found two cell types in the fat body of this tick. The,fat body of a related tick produces vitellogenin during oviposition. The purpose of this study was to examine the ultrastructure of the fat body in the life stages of D. variabilis.Ticks were from a colony maintained at Memphis State University. Ticks were fed on rabbits. Tissue was fixed in situ in 2.5% glutaraldehyde in 0.1M sodium cacodylate, pH 7.2 for 1 hour, post-fixed in 1% OsO4 in the same buffer, dehydrated in an ascending series of acetone and embedded in Epon Araldite. Sections were examined in a Zeiss 10A TEM operated at 60KV.
Characterization of Si(Li) x-ray detector efficiencies in the low energy range
Authors: Wirmark G. , Wahlberg G. , Nordén H. 
Published: June 2020

X-ray microanalysis with windowless or ultra-thin window Si(Li)-detectors is becoming increasingly important in analytical electron microscopy. The most common approach in the quantification of this method is the thin film ratio method.where CA and CB denote the concentrations of elements A and B respectively and IA and IB are the corresponding x-ray intensities. The KAB-factor should ideally be determined from analyses of standard specimens of known compositions.
Fractionation of polymethylene chains: An electron crystallographic investigation
Authors: Dorset Douglas L. 
Published: June 2020

A variety of linear chain materials exist as polydisperse systems which are difficultly purified. The stability of continuous binary solid solutions assume that the Gibbs free energy of the solution is lower than that of either crystal component, a condition which includes such factors as relative molecular sizes and shapes and perhaps the symmetry of the pure component crystal structures.Although extensive studies of n-alkane miscibility have been carried out via powder X-ray diffraction of bulk samples we have begun to examine binary systems as single crystals, taking advantage of the well-known enhanced scattering cross section of matter for electrons and also the favorable projection of a paraffin crystal structure posited by epitaxial crystallization of such samples on organic substrates such as benzoic acid.
MTF restoration with slow-scan CCD cameras
Authors: Mooney P.E. , de Ruijter W.J. , Krivanek O.L. 
Published: June 2020

Slow-scan CCD cameras (SSCs) attached to transmission electron microscopes (TEMs) are proving invaluable in the acquisition of TEM images and in providing high quality data for on-line analysis and autotuning procedures. When equipped with a sensitive phosphor and an efficient fiber-optical coupling, they are able to record the arrival of single fast electrons. At more typical exposure levels of 10 -1000 fast electrons per pixel, they are able to capture images while adding less noise than the Poisson noise inherent in any electron image.The raw images captured by the SSC suffer from various defects, but these can be corrected on-line in the computer used to record the images. The most familiar defect is the pixel-to-pixel gain variation, which is readily corrected by capturing a gain-reference image and then performing on-line gain-normalization. Another significant defect in raw images is that the signal due to each arriving electron is spread overseveral pixels.