bluuebunny/crossref_metadata_2025_split huggingface dataset:
Is spectrometer resolution or system count rate performance more important in quantitative energy-dispersive x-ray microanalysis?
Authors: Fiori C.E. , Swyt C.R. 
Published: June 2020

Recently, important improvements have been achieved in both the resolution of energy dispersive spectrometers (EDS) and their count rate performance. Figure 1 is a plot of the count rate performance versus resolution for one EDS system. This particular system was chosen for our study because data were available for 6 pulse processing times. It can be seen that there is a direct trade off between count rate performance and energy resolution. The purpose of this study is to examine the consequences of the various pulse processor conditions for quantitative analysis. A number of analytical problems were simulated including various combinations of acquisition times, degree of spectral overlap, and relative peak heights.We provide here one example from the study, the analysis of PbS, which offers a difficult spectral overlap of the Pb M lines and the S K lines. We used the recently available computer program DTSA (Desk Top Spectrum Analyzer), to simulate 1000 spectra for each of the pulse processor resolution conditions shown in Figure 1. A linear least squares procedure was used to determine the peak areas.
SIMS studies of Ca and Mg distributions in sintered Al2O3
Authors: Soni K. K. , Thompson A. M. , Harmer M. P. , Williams D. B. , Chabala J. M. , Levi-Setti R. 
Published: June 2020

The addition of MgO to α-Al2O3 has been practiced for over 30 years in order to improve greatly the properties of the sintered material. However, a complete understanding of the role of MgO has not been achieved despite significant research efforts by various groups. The most difficult obstacle is microchemical characterization of MgO doped Al2O3. Surface analytical techniques, primarily AES and XPS, have been employed by past researchers in order to analyze the grain boundaries on fractured surfaces of sintered Al2O3. This prior work has met with limited success due to poor sensitivity and spatial resolution. MgO is believed to segregate to the grain boundaries and to retard the grain boundary mobility via a solute drag mechanism; this hypothesis has not been verified experimentally.In this study, the distribution of Ca and Mg was characterized by a high lateral resolution scanning ion microprobe (SIM) developed at The University of Chicago (UC).
Characterisation of nicalon fibres using EPMA
Authors: Love G , Bleay SM , Chapman AR , Scott VD 
Published: June 2020

Nicalon is a fibre produced commercially by melt spinning a mixture of silanes and pyrolising the product. This gives a ceramic fibre, based upon silicon carbide, used for reinforcing metallic and composite materials. The composition of Nicalon is not fully understood but in addition to silicon carbide the presence of free carbon, and silica have been reported together with a non-stoichiometric oxycarbide.EPMA was carried out on transverse fibre sections prepared from a plate of metal matrix composite using a JEOL 8600M fitted with wavelength dispersive spectrometers. Quantitative data were obtained at a voltage of 15kV using reference standards of silicon carbide (for silicon and carbon analysis) and silica (for oxygen). The analyzing crystals employed for recording CK, OK and SiKα radiation were lead stearate, a W-Si multlilayer (2d = 7nm) and PET respectively. Peak intensity measurements were used except in the case of CK radiation where area measurements were necessary because of obvious differences in peak shape from Nicalon and SiC.
On the Simulation of EEL Spectra Corresponding to Solid and Gaseous Samples
Authors: Zanchi G. , Kihn Y. , Sévely J. 
Published: June 2020

The electron energy loss spectra can be considered as the result of the convolution of elementary inelastic scattering processes (1, 2). We have developed a procedure which allows to write the intensity of the spectrum as a function of the energy loss.These calculations take the electron angular scattering into account.The probability for an electron to suffer an energy loss E and to be deviated through an angle after a single electron-electron interaction of any kind is given by a normalized function D(E, ), which can be written with a good approximation as a product of two functions g(E) and f(), separately normalized. Assuming that the excitation probabilities of any interaction follows a Poisson distribution, for a collection angle θd the intensity of the spectrum can be written in the Fourier space :Gs(ω) is the Fourier transform of GS(E) which characterizes the transfer function of the experimental device.
Angle-Resolved Energy-Loss Spectra of Gd2O3
Authors: Schattschneider P. , Hofer F. 
Published: June 2020

Energy loss spectra of heavy rare earths oxides show two well defined plasmon-like peaks below 40 eV and some intensity variation beyond. Since the high-energy maximum is at about twice the energy as the low-energy maximum, double scattering contributions may mask the former. This effect induces artifacts when one attempts to determine the dielectric function ε(ω) from Kramers-Kronig-analysis (KKA) of the loss spectrum. Knowledge of ε(ω) allows to heuristically assign interband transitions or plasma excitations to particular maxima. Measurements in diffraction mode allow detection of dispersive features in ε(ω,q).Polycrystalline Gd2O3-films of of 40 nm thickness were investigated at 120 kV in a Philips EM420, attached to which is a Gatan 607 Spectrometer. Spectra were taken in diffraction mode (image coupling) at 8 scattering angles with a q-resolution of ≈ 0.03 Å-1. Energy resolution was ≈ 2 eV. The spectra were combined to a q-dependent loss function, using aperture correction.
On Mode Selection for Quantitative Electron-Energy-Loss-Spectroscopy
Authors: Yang Ying-Ying , Egerton Ray F. 
Published: June 2020

The present work shows that, without great care, quantitative EELS measurement using the diffraction mode of TEM operation could be quite inaccurate. In the diffraction mode, a zero-loss diffraction pattern is focused on the TEM viewing screen while the focal plane of the lossy pattern is somewhere above the screen, due to lens chromatic aberration effects. For small to medium camera length, the distance between the focal plane of the lossy pattern and the focal plane of the zero-loss pattern is much smaller than the distance between the zero-loss and lossy images in image mode, for normally used magnification (10,000 or more). However, this smaller distance is not sufficient to ensure that spectrometer-collection efficiencies are more equal for different energy electrons in the diffraction mode compared to those in the image mode.As shown in Figure 1, lossy diffraction spots expand to discs on the viewing screen because their focal plane lies above the viewing screen.
Coordination “Fingerprints” of Boron Measured by EELS
Authors: Sauer H. , Brydson R. , Engel W. , Rowley P.N. 
Published: June 2020

The electron energy-loss near-edge structure (ELNES) associated with a core-loss edge measured using electron energy-loss spectroscopy (EELS) provides, in favourable cases, a “fingerprint” corresponding to the specific nearest-neighbour coordination of the excited atom.Boron atoms in boron-oxygen compounds occur in both trigonal (BO3) and tetrahedral (BO4) coordinations. The B K-ELNES of BO3 and BO4 units (Figs, le and 2b) are remarkably different and arise from the differing local symmetries which determine the final state molecular orbitals. The BK-ELNES of BO3 units exhibit a sharp π∗ peak at ca. 194 eV followed by a broader σ∗ peak some 9-10 eV higher in energy, which may possess a low energy shoulder. BO4 B K-ELNES show no π∗ peak and display solely a σ∗ peak at ca. 199 eV together with a high energy shoulder. Both these spectra may be modelled using multiple scattering calculations.The mineral howlite contains both BO3 and BO4 units and is sensitive to electron-beaminduced damage.
Comparison of Calculated and Recorded Electron Energy-Loss Spectra of Aluminium and Carbon
Authors: Reimer L. , Oelgeklaus R. 
Published: June 2020

Quantitative electron energy-loss spectroscopy (EELS) needs a correction for the limited collection aperture α and a deconvolution of recorded spectra for eliminating the influence of multiple inelastic scattering. Reversely, it is of interest to calculate the influence of multiple scattering on EELS. The distribution f(w,θ,z) of scattered electrons as a function of energy loss w, scattering angle θ and reduced specimen thickness z=t/Λ (Λ=total mean-free-path) can either be recorded by angular-resolved EELS or calculated by a convolution of a normalized single-scattering function ϕ(w,θ). For rotational symmetry in angle (amorphous or polycrystalline specimens) this can be realised by the following sequence of operations :(1)where the two-dimensional distribution in angle is reduced to a one-dimensional function by a projection P, T is a two-dimensional Fourier transform in angle θ and energy loss w and the exponent -1 indicates a deprojection and inverse Fourier transform, respectively.
PRSUPR: A PC Based Automation and Data Reduction Software Package for Wavelength Dispersive Electron Beam Micro-Analysis
Authors: Donovan John J. , Rivers Mark L. 
Published: June 2020

Although several commercial automation packages are available for use on the micro-probe, we at Berkeley feel that they all suffer from a number of shortcomings. A few of the most important features missing are :1.The ability to produce quantitative results of the highest accuracy over the entire analytical range of the micro-probe using the most advanced matrix correction software available.2.A simple yet versatile user interface making extensive use of multiple choice menus and defaulted experimental parameters for exceptional ease of use.3.Full support of manual and automated modes for both standard and unknown samples for a wide variety of sample configurations and analytical methods.4.Hardware independence and completely configurable program for various micro-probe stage and spectrometer arrangements for use with any micro-probe hardware.5.Capability on a PC for BOTH real-time on-line data acquisition and analysis when connected to the micro-probe, and off-line analysis of data when not connected.6.Ability to run on an inexpensive and widely available computer platform without the need for graphics hardware.
Resolution Enhancement for X-RAY Spectroscopy at Low Energies
Authors: Statham Peter 
Published: June 2020

For microanalysis with Si(Li) EDX systems, the procedures for background subtraction and peak overlap correction, by least-squares fitting for example, are well established. However, the use of EDX as a research tool to investigate the precise form of the x-ray spectral distribution (i.e. “spectroscopy”) is much less common. In the region from 0 to 1keV, matrix effects such as absorption in the sample are strong, x-ray line profiles are affected by chemical effects and relative line intensities often differ from the simplistic descriptions suggested by “slide rules” and “KLM” markers so this is a particularly interesting region to study. EDX is suitable for spectroscopy because the efficiency is usually more reproducible than that for a Bragg crystal spectrometer. However, the resolution is not sufficient to see many of the above effects so it is worth considering what prospects there are for enhancement.In theory, monochromatic x-radiation of energy E eV produces a Gaussian spectral peak in an EDX energy histogram with resolution given bywhere F is the “Fano factor”.
Development of Field-Emission Gun for High-Voltage Electron Microscope
Authors: Tomita T. , Katoh S. , Kitajima H. , Kokubo Y. , Ishida Y. 
Published: June 2020

It is well known that the combination of a field emission gun (FEG) and a conventional transmission electron microscope (CTEM) is extremely important for nanometer area analysis in analytical electron microscopy. However, the smaller illumination angle and reduced energy spread of FEG than those of a conventional electron gun (W hair pin filament or LaB6) give a slowly damping envelop function in phase contrast transfer function (PCTF). Thus the FEG ensures application not only to analytical microscopy but also to high resolution electron microscopy to improve the information limit.In a high voltage electron microscope (above 200 kV), high-speed vacuum pumps have to be provided below the acceleration tube to get an ultra high vacuum (UHV) around the field emission tip located at the top of the acceleration tube. However, this method is not always the best way to provide UHV because of the poor vacuum conductance caused by the electrodes inside the acceleration tube.
X-ray microanalysis of cardiac myocytes isolated from K-depleted rabbits
Authors: Warley Alice , Ward Jeremy P.T. 
Published: June 2020

Chronic heart disease is conmonly associated with electrolyte disturbances, including hypokalemia and K depletion. Previous work suggests that chronic K depletion results in an adaptive increase in the density of the membrane bound sodium pump. Such altered properties of the sarcolemma should be reflected in the composition of cardiac myocytes isolated from control and K depleted animals.Adult male NZW rabbits were fed either a standard diet or a diet deficient in K. The animals were anaesthetised, the hearts removed, and myocytes were isolated by collagenase disaggregation. Cells from control animals were kept in a medium containing 4 mM extracellular K to mimic normal serum concentrations of this element. Cells from K depleted animals were maintained in solutions containing either 2 mM external K, (K concentration in serum from depleted animals) or 4mM K to mimic repletion. The cells were concentrated by centrifugation (500 g, 5 min), the supernatant removed, and drops of the pellet quench frozen in liquefied propane.
Subcellular calcium content of myocardium after ischemia and reperfusion: X-ray microanalysis
Authors: Horikawa Yoshifumi , Kaneko Noboru , Uchida Tatsuroh , Hosoda Saichi , Teraoka Kunihiko , Nakamura Sachiko 
Published: June 2020

We have reported that calcium accumulation inside the mitochondria was induced by ischemia. Other authors have reported similar results. But there has been no study to clarify whether calcium accumulation in the mitochondria is reversible or irreversible. The goal of this study is to clarify whether calcium content in the mitochondria is changed by reperfusion for 60 minutes.9 male rats (17- 20 weeks old) were used. After cervical fracture, the heart was quickly excised and the aorta was cannulated. We circulated Krebs-Henseleit solution at 37°C. Samples were divided into three groups. The control group was perfused with 95%O + 80cmH2O Krebs-Henseleit solution for 30 minutes. The ischemic group was perfused with 50%O2 + 15cmH2O solution for 30 minutes. In the reperfusion group, control solution was circulated for 60 minutes after 30 minutes ischemic perfusion. Just after perfusion, specimens were taken from the papillary muscle of the left ventricle and rapidly frozen by the metal contact method.
Mitochondrial matrix calcium ions regulate energy production in myocardium: A cytochemical study
Authors: Jacob W.A. , Hertsens R. , Van Bogaert A. , De Smet M. 
Published: June 2020

In the past most studies of the control of energy metabolism focus on the role of the phosphorylation potential ATP/ADP.Pion the regulation of respiration. Studies using NMR techniques have demonstrated that the concentrations of these compounds for oxidation phosphorylation do not change appreciably throughout the cardiac cycle and during increases in cardiac work. Hence regulation of energy production by calcium ions, present in the mitochondrial matrix, has been the object of a number of recent studies.Three exclusively intramitochondnal dehydrogenases are key enzymes for the regulation of oxidative metabolism. They are activated by calcium ions in the low micromolar range. Since, however, earlier estimates of the intramitochondnal calcium, based on equilibrium thermodynamic considerations, were in the millimolar range, a physiological correlation was not evident. The introduction of calcium-sensitive probes fura-2 and indo-1 made monitoring of free calcium during changing energy metabolism possible. These studies were performed on isolated mitochondria and extrapolation to the in vivo situation is more or less speculative.
Biomedical elemental analysis and imaging using synchrotron x-ray microscopy
Authors: Jones K. W. , Gordon B. M. , Schidlovsky G. , Spanne P. , Dejun Xue , Saubermann A. J. 
Published: June 2020

The application of synchrotron x-ray microscopy to biomedical research is currently in progress at the Brookhaven National Synchrotron Light Source. The current status of the x-ray microscope (XRM) from a technical standpoint is reviewed. Some of the items considered are photon flux, spatial resolution, quantitation, minimum detection limits, and beam-induced specimen damage. Examples of measurements made with the XRM are then given.The XRM has generally used continuous energy bending magnet radiation as the x-ray source. A mechanical collimator placed close to the specimen is used to define x-ray beams of 3-5/μm size. The size of the beam can be adjusted to some extent by tilting the collimator with respect to the beam direction. The photon flux is maximized by locating the XRM as close to the x-ray source as possible (9 m). Flux values of about 3 × 108 photons/(s-μm2) are obtained with a 100mA current of electrons in the storage ring.
Investigation of thin sections of biological standards by EDX, EELS, and Auger electron spectroscopy
Authors: Lehner S. , Bauer H.E. , Wurster R. , Seiler H. 
Published: June 2020

In order to compare different microanalytical techniques commercially available cation exchange membrane SC-1 (Stantech Inc, Palo Alto), was loaded with biologically relevant elements as Na, Mg, K, and Ca, respectively, each to its highest possible concentration, given by the number concentration of exchangeable binding sites (4 % wt. for Ca). Washing in distilled water, dehydration through a graded series of ethanol, infiltration and embedding in Spurr’s low viscosity epoxy resin was followed by thin sectioning. The thin sections (thickness of about 50 nm) were prepared on carbon foils and mounted on electron microscopical finder grids.The samples were analyzed with electron microprobe JXA 50A with transmitted electron device, EDX system TN 5400, and on line operating image processing system SEM-IPS, energy filtering electron microscope CEM 902 with EELS/ESI and Auger spectrometer 545 Perkin Elmer.With EDX, a beam current of some 10-10 A and a beam diameter of about 10 nm, a minimum-detectable mass of 10-20 g Ca seems within reach.
Fluorescence effects in quantitative microprobe analysis
Authors: Reed S.J.B. 
Published: June 2020

Characteristic fluorescenceThe theory of characteristic fluorescence corrections was first developed by Castaing. The same approach, with an improved expression for the relative primary x-ray intensities of the exciting and excited elements, was used by Reed, who also introduced some simplifications, which may be summarized as follows (with reference to K-K fluorescence, i.e. K radiation of element ‘B’ exciting K radiation of ‘A’):1.The exciting radiation is assumed to be monochromatic, consisting of the Kα line only (neglecting the Kβ line).2.Various parameters are lumped together in a single tabulated function J(A), which is assumed to be independent of B.3.For calculating the absorption of the emerging fluorescent radiation, the depth distribution of the primary radiation B is represented by a simple exponential.These approximations may no longer be justifiable given the much greater computing power now available. For example, the contribution of the Kβ line can easily be calculated separately.
Automated mineral analysis in TASK8
Authors: Chambers William F. , Chodos Arthur A. , Hagan Roland C. 
Published: June 2020

TASK8 was designed as an electron microprobe control program with maximum flexibility and versatility, lending itself to a wide variety of applications. While using TASKS in the microprobe laboratory of the Los Alamos National Laboratory, we decided to incorporate the capability of using subroutines which perform specific end-member calculations for nearly any type of mineral phase that might be analyzed in the laboratory. This procedure minimizes the need for post-processing of the data to perform such calculations as element ratios or end-member or formula proportions. It also allows real time assessment of each data point.The use of unique “mineral codes” to specify the list of elements to be measured and the type of calculation to perform on the results was first used in the microprobe laboratory at the California Institute of Technology to optimize the analysis of mineral phases. This approach was used to create a series of subroutines in TASK8 which are called by a three letter code.
Macroprobe Mode for the Study of Segregation in Steels
Authors: Gilles Auclair , Danièle Benoit 
Published: June 2020

During these last 10 years, high performance correction procedures have been developed for classical EPMA, and it is nowadays possible to obtain accurate quantitative analysis even for soft X-ray radiations. It is also possible to perform EPMA by adapting this accurate quantitative procedures to unusual applications such as the measurement of the segregation on wide areas in as-cast and sheet steel products.The main objection for analysis of segregation in steel by means of a line-scan mode is that it requires a very heavy sampling plan to make sure that the most significant points are analyzed. Moreover only local chemical information is obtained whereas mechanical properties are also dependant on the volume fraction and the spatial distribution of highly segregated zones. For these reasons we have chosen to systematically acquire X-ray calibrated mappings which give pictures similar to optical micrographs. Although mapping requires lengthy acquisition time there is a corresponding increase in the information given by image anlysis.
Influence of Smoking on Asbestos Phagocytosis by Macrophages in Guinea Pigs
Authors: Gray L.D. , Brady D.E. , Holiday D.B. , Swinford G.L. 
Published: June 2020

Cigarette smoking greatly enhances the risk of lung cancers of all types in persons occupationally exposed to asbestos (1). Pulmonary macrophage recruitment and subsequent phagocytosis of asbestos fibers has been shown to occur within hours of asbestos exposure in guinea pigs (2) and is the predominant and chronic phagocytic response after about 1-2 days post exposure. In an initial qualitative examination of lung tissues from smoke and asbestos exposed guinea pigs (3), a number of macrophages were observed which had engulfed large numbers of asbestos fibers. A morphometric analysis was performed to examine the effect of cigarette smoke exposure on the phagocytosis of asbestos by guinea pig pulmonary macrophages in vivo, and specifically, to determine if phagocytosis was increased in animals exposed to both smoke and asbestos.We used three treatment groups of male, Hartley guinea pigs. Each group (n=4) received the same level of asbestos exposure (15mg Amosite 3 times, 1 dose/week) and varied levels of smoking exposure.