bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Chemical Analysis of Sub-Micron Phase Segregation In Polyurethane Polymers by Soft X-Ray Spectromicroscopy
Authors: Hitchcock AP , Urquhart SG , Rightor EG , Lidy W , Ade H , Smith AP , Warwick T 
Published: July 2020

Abstract
Phase segregation is important in determining the physical and chemical properties of many complex polymers, including polyurethanes. Achieving a better understanding of the connections between formulation chemistry, the chemical nature of segregated phases, and the physical properties of the resulting polymer, has the potential to greatly advance the development of improved polyurethane materials. However, the sub-micron size of segregated features precludes their chemical analysis by most existing methods. Near edge X-ray absorption spectroscopy carried out with sub micron spatial resolution provides one of the few suitable means for quantitative chemical analysis (speciation) of individual segregated phases. We have used the NSLS and ALS scanning transmission x-ray microscopes (STXM) to record images and spectra of both model and real polyurethane polymers. Relative to energy loss spectroscopy in a transmission electron microscope, STXM has remarkable advantages with regard to a much lower radiation damage rates and much higher spectral resolution (∼0.1 eV at the C ls edge), with a spatial resolution (∼0.1 μm) adequate for many real world problems in polymer analysis.
Correlation Between Functional Recovery From Ischemia and Sarcoplasmic Reticulum Calcium Content Measured by Electron Probe MicroAnalysis
Authors: Barrett LS , Sweet WE , Moravec CS 
Published: July 2020

Abstract
Myocardial ischemia is defined as a cessation of blood flow to the heart, and reperfusion as a return to normal flow conditions following ischemia. It has been shown that contractility decreases immediately during ischemia and diastolic dysfunctiuon may persist during reperfusion. Changes in contractility can be directly attributed to intracellular Ca2+ handling, either by altering the myofilament sensitivity to calcium or by affecting Ca2+ cycling by the sarcoplasmic reticulum (SR). Previous studies have demonstrated that there are changes in intracellular Ca2+ cycling following ischemia and during reperfusion. The goals of the present study were: 1) to assess the effects of varying periods of ischemia on the size of the releasable (diastolic) SR Ca2+ store; 2) to determine whether changes in the size of the SR Ca2+ store are related to ischemia or reperfusion; 3) to correlate changes in the size of the SR Ca2+ store following ischemia with functional recovery of the heart.
Magnesium Content and Distribution During Differentiation of Hl60 Cells
Authors: Di Francesco A , Desnoyer RW , Wolf FI , Covacci V , Cittadini A , Bondt M 
Published: July 2020

Abstract
Mg is present in all living cells as free and bound Mg. Previous observations have shown a positive correlation between total Mg content and proliferative rate in several different cell types (1). To investigate the association between Mg and cell proliferation, we utilized a human promyelocytic leukemia cell line, HL60, that can be induced to differentiate in vitro to neutrophil-like cells, by retinoic acid (RA) and other compounds.
To further investigate this question, we analyzed elemental compartmentalization in HL60 cells before and after differentiation using electron probe microanalysis (EPMA). Differentiation to neutrophil-like cells was induced by culturing the HL60 cells for 96 hours in the presence of 1 μM RA. Cells were washed, pelleted, then rapidly frozen in liquid ethane, cooled to -185°C with liquid N2. Ultrathin cryosections were cut from the surface of the frozen cells, freeze-dried overnight and carbon coated. X ray spectra were collected at -100°C and at 80 keV accelerating voltage in a Philips CM 12 STEM equipped with LaB6 gun and an EDAX 30-mm2 Si(Li) energy dispersive x-ray detector and multichannel analyzer.
Towards The Automatic Segmentation of Multiple Micro Analytical Maps
Authors: Bonnet N 
Published: July 2020

Abstract
Multi-dimensional data sets are now produced by many analytical instruments. They include the series of spectra, the series of images and spectrum-images, which can be considered as a series of spectra at different positions or series of images at different wavelengths.
The automatic (or semi-automatic) handling of such data sets requires that new multivariate analysis methods are made available. For instance, if we restrict ourselves to image sets, there is a need to deduce (from the multiple maps) a single map in which regions of the specimen with approximate homogeneous properties (composition...) can be identified and quantified.
At the present time, only a limited number of software tools are available for this purpose:- the scatterplot allows the display of the correlations between two or three spectra or images,- Interactive Correlation Partitioning (ICP) allows the user to divide the scatterplot into several parts and to reconstitute images with one selected part,-Multivariate Statistical Analysis (MSA) allows us to analyze a data set composed of several images and to identify the different sources of information, and to filter out noise and experimental artefacts.
Multivariate Statistical Analysis of Spectrum Lines and Images
Authors: Anderson Ian M , Bentley Jim 
Published: July 2020

Abstract
Recent developments in instrumentation and computing power have greatly improved the potential for quantitative imaging and analysis. For example, products are now commercially available that allow the practical acquisition of spectrum images, where an EELS or EDS spectrum can be acquired from a sequence of positions on the specimen. However, such data files typically contain megabytes of information and may be difficult to manipulate and analyze conveniently or systematically. A number of techniques are being explored for the purpose of analyzing these large data sets. Multivariate statistical analysis (MSA) provides a method for analyzing the raw data set as a whole. The basis of the MSA method has been outlined by Trebbia and Bonnet.
MSA has a number of strengths relative to other methods of analysis. First, it is broadly applicable to any series of spectra or images. Applications include characterization of grain boundary segregation (position-), of channeling-enhanced microanalysis (orientation-), or of beam damage (time-variation of spectra).
Data Categorization and Neural Pattern Recognition
Authors: Gatts C , Mariano A 
Published: July 2020

Abstract
The natural ability of Artificial Neural Networks to perform pattern recognition tasks makes them a valuable tool in Electron Microscopy, especially when large data sets are involved. The application of Neural Pattern Recognition to HREM, although incipient, has already produced interesting results both for one dimensional spectra and 2D images.
In the case of ID spectra, e.g. a set of EELS spectra acquired during a line scan, given a “vigilance parameter” (which sets the threshold for the correlation between two spectra to be high enough to consider them as similar) an ART-like network can distribute the incoming spectra into classes of similarity, defining a standard representation for each class. In order to enhance the discrimination ability of the network, the standard representations are orthonormalized, allowing for subtle differences betwen spectra and peak overlapping to be resolved. The projection of the incoming vectors onto the basis vectors thus formed gives rise to a profile of the data set.
Application of Nano-Scale Eels Spectrum Lines To Grain Boundaries
Authors: Bruley J , Cho J , Hanner MP , Chan HM 
Published: July 2020

Abstract
Polycrystals containing small quantities of impurity can exhibit dramatically different properties from that of the pure material. One example of this is the tenfold increase in the creep resistance of Y or La doped alumina relative to ultra-pure alumina. Such changes are correlated to grain boundary segregation, however the segregant’s potency to influence properties remains unexplained. Determining the driving force to segregation only partially addresses this issue. A full understanding must take account of the chemical bonding and structural changes occurring at the boundary after segregation. The purpose of this study is to observe the electronic structure associated with the segregating species using EELS spectrum-line profiling. This is accomplished by monitoring the segregation profile along with the characteristic near edge absorption fine structures which reflect changes in the localized density of unoccupied states along that profile. In these experiments a finely focused beam was sequentially stepped across the boundary of interest and a spectrum recorded at each step.
Improved Measurement and Analysis of Series of Valence Electron Energy Loss Spectra and The Local Electronic Structure
Authors: Müllejans H , French R H , Duscher G , Rühle M 
Published: July 2020

Abstract
The local electronic structure of ceramic materials can be determined from valence electron energy loss (Veel) spectra via the dielectric function. The quality of the data is comparable to vacuum ultraviolet spectroscopy with the added benefit of high spatial resolution. We have built and implemented a system for spectrum imaging which not only allows automatic data acquisition but also analysis of the full data set. The system consists of a Gatan PEELS and a Gatan Digiscan fitted to a VG HB501 UX STEM and home-built hardware additions. The hardware extensions allow to acquire 1, 2, 3, 4 or 8 spectra for each pixel and in the case of 2 spectra/pixel to vary the exposure time of the specimen to the primary electron beam by controlling the beam blanker (Fig. 1). The first spectrum (2 to 20 ms) contains an unsaturated zero loss peak and the second spectrum (0.05 to 100 s) at the same position the plasmon peak near to but below saturation (Fig. 2).
Ab-Initio Calculations of Density of States for Ti-Oxide
Authors: Duscher G , Köstlmeier S , Meyer B , Elsässer C , Browning N 
Published: July 2020

Abstract
Electron energy-loss spectroscopy (EELS) has been shown to be a powerful tool to determine not only the chemistry, but also the electronic and atomic structure at grain boundaries by analysing the energy-loss near-edge structure (ELNES). However, as the experimental ability to obtain quality spectra from interfaces with high-spatial resolution is relatively new, the interpretation of ELNES has been mostly qualitative. Here we discuss the ability of ab-initio density of state calculations to perform detailed quantitative analysis at interfaces.
In this methodology, ignoring any multiparticle effects such as excitons, the ELNES can be described as the symmetry projected density of states (DOS) and a matrix element varying slowly with energy. The calculated DOS, which best reproduce the experimental ELNES, are obtained using density functional theory (DFT) in the local density approximation (LDA) (i.e.: Weng et al.). Traditionally, because a high number of atoms (&gt; 60) is needed to reproduce the periodicity of interface structures, more approximate methods such as the real-space multiple scattering method3 and its equivalent in reciprocal space (KKR-method) were used.
Electronic Structure Investigations of γ-Tial.
Authors: Lie K , Holmestad R , Marthinsen K , Høier R 
Published: July 2020

Abstract
The intermetallic compound TiAl is a promising material for applications at high stress and high temperature. It has good balance between lightness, strength and oxidation resistance, but suffers of an intrinsic brittleness at lower temperature. Small, ternary additions of V, Cr or Mn are known to increase the ductility of this material. In the present and a recent study we have used electron energy loss spectroscopy as a sensitive test to investigate the electronic structure in these materials. The near edge structure (NES) may give complementary information to e.g. convergent beam electron diffraction (CBED) about the bonding character in these materials.
EELS spectra were collected using a Gatan 666 spectrometer with parallel recording fitted to a Philips CM 30 transmission electron microscope operating at a nominal voltage of 150 kV. The energy resolution (measured as full width at half maximum) was typically around 1 eV. Spectra from areas of similar thickness, as measured relative to the total inelastic mean free path of the 150-keV electrons were obtained.
Local Temperature Determination Using Elfs Spectroscopy
Authors: Qian M , Sarikaya M , Stern E A 
Published: July 2020

Abstract
ELFS spectroscopy (energy loss fine structure) is used to obtain local atomic structure information It can outperform XAFS (x-ray absorption fine structure) not only because of its low Z element sensitivity, but also because of its high spatial resolution and the capability of combining other high resolution TEM measurements. Although TEM continues to gain importance as an indispensable and unique tool to study nanoscale phenomena by providing simultaneous imaging, diffraction, and spectroscopy information, direct observation and quantitative measurements of physical phenomena are also desirable. This paper gives a first-time demonstration of such a measurement, namely local temperature determination in a TEM sample by ELFS.
The principle is simple and as follows. One can measure, with ELFS, the atomic distances up to ±0.01 Å accuracy for the fist shell (typically around 2 Å ) and the second shell (around 3-4 Å). Atomic distances in a sample will change when its temperature changes, the phenomena that are coupled by the macroscopic temperature dependent lattice expansion.
Imaging of Elastic and Inelastic Electron Scattering in Diamond
Authors: Bell David C 
Published: July 2020

Abstract
The physical properties of diamond are some of the most interesting of natural materials. Electron energy-loss spectroscopy studies of a single crystal diamond wedge allow some of the basic electron matter interactions to be studied. The electron energy-loss spectrum has been examined with particular reference to the plasmon excitations in the crystal. The mean-free path of the electrons through the diamond crystal and the nature of the observed features in the energy-loss spectrum have been examined.
A single crystal of diamond was cut and polished to produce a diamond wedge with a 33° angle making it suitable for observation in a transmission electron microscope (Fig. 1). The determination of the geometrical parameters of the crystal wedge involved the analysis of pendellosung fringes (Fig. 2) and comparisons to bloch wave calculations. The gradient analysis plot shown in Fig. 3 allowed the wedge thickness to be determined at any distance from the edge.
Analytical TEM Study of Nanophase Precipitation in Nial Alloys
Authors: Wilson A W , Howe J M , Garg A , Noebe R D 
Published: July 2020

Abstract
Alloying additions have been found to enhance the mechanical properties of NiAl through solid solution strengthening and the precipitation of 2°d phases. The precipitation of fine, homogeneously nucleated ß' (Ni2Al (Ti,Hf)) has been observed and characterized by dark-field imaging and electron diffraction. The exact composition of these and other precipitates, however, remains unknown. In this study, the composition of the fine ( &lt;20 nm) ß’ precipitates in NiAl alloys is measured and compared to that of well-developed ß’ plates in the matrix.
Two directionally solidified NiAl single-crystal alloys, NiAl-3Ti-0.5Hf and NiAl-7Ti (at.%) were grown by a Bridgeman technique using high purity alumina crucibles. Both ingots were homogenized for 32 h at 1644 K. In addition, the NiAl-3Ti-0.5Hf sample was aged at 1255 K for 6 h and furnace cooled. Samples for transmission electron microscopy were prepared from 3 mm diameter cylinders electro-discharge machined from the heat-treated ingots.
Orientation Analysis by Computer-Aided Diffraction Pattern Matching in The TEM
Authors: Thomas L E , Hugo R C , Stanley J T 
Published: July 2020

Abstract
Electron diffraction patterns taken in transmission electron microscopes are widely used for phase identification and orientation determination of crystallites as small as hundreds or even tens of nanometers in size. The analyses typically require rather tedious measurement of the patterns, and matching of calculated d-spacings and angles with those of known phases. Recently, the analysis of these patterns has been facilitated by powerful desktop computer programs that use digitally captured images for on-line measurement and simulation matching of" the diffraction spot and Kikuchi line patterns. This presentation will illustrate an application of computer-aided pattern simulation and matching for precise determination of crystal orientations.
Two experimental TV camera arrangements were used to record diffraction patterns in a TEM. These included a cooled-CCD camera located on the electron optical axis below the microscope viewing chamber, and a simple TV-rate CCD that recorded directly from the inclined fluorescent viewing screen of the microscope.
Alternative Collection Mode for Rdf Acquisition in Feg-STEM
Authors: Bell David C , Garratt-Reed Anthony J , Hobbs Linn W 
Published: July 2020

Abstract
Overview Radial distribution function (RDF) information obtained from amorphous glasses can provide important near and medium range structure information, determination of this information has important consequences for the encapsulation and the long term stability of nuclear waste material.
RDF data has been obtained from samples of waste glass and amorphous quartz. This data was obtained using a Vacuum Generators HB603 FEG-STEM, equipped with a GATAN Digi-PEELS. Post specimen scanning was employed to minimize the effect of spherical aberration that is present in the incident beam rocking mode.
Previous data obtained using the main-scan coils and rocking the incident beam on the specimen, diffraction information collected from out to 16 nm-1. The intensity of the information falls of rapidly as the inverse forth power of the scattering angle, out to the point where the signal to noise of the detector becomes unity. This point is limited by the sensitivity of the detector and the spherical aberration of the objective lens which limits the ultimate collection angle, regardless of the sensitivity of the detection system.
Surface Structures from Direct Methods Using a Genetic Algorithm
Authors: Landree E , Collazo-Davila C , Marks L D 
Published: July 2020

Abstract
Two two-dimensional atomic models were constructed to test the application of Direct Methods for solving surface crystal structures (atomic positions are listed in Table 1). The use of Direct Methods to solve three dimensional structures from X-ray diffraction has been well established for several years. However to the best of our knowledge never before had this technique been applied to 2-D surface structures. A Genetic Algorithm (GA) search routine was implemented for exploring possible solutions.
The models were constructed using electron scattering factors to calculate the intensities and phases for beams out to 1 Å resolution (Fig. 1). Since electron diffraction from surfaces has been shown to be nearly kinematical X-ray and electron scattering can be handled identically. An error term was applied to the generated intensities to simulate realistic sampling errors. The generated phases for each model were removed and later used to monitor the solutions calculated by the direct methods.
Evaluation of the Structure Factor of Cuprite and Bonding Chracterisitcs
Authors: Kim M Y , Zuo J M , Spence J C H 
Published: July 2020

Abstract
Cu2O is a semiconductor with a band gap of 2.17eV, and its crystal structure is simple cubic. Oxygen atoms form a bcc structure and each oxygen atom is tetrahedrally coordinated by copper atoms, which makes copper linearly coordinated by two oxygen atoms. The structure of cuprite is interesting because the charge state of Cu and oxygen. The most common charge states of Cu is 2+, however, in cuprite for each oxygen there are two Cu atoms which suggest a 1+ charge state of Cu. Charge density of Cu and oxygen are also interesting because of the high Tc superconductors based on copper and oxygen planes and chains. The superconductivity is believed due to the different charge states of copper and/or oxygen in the Cu-oxygen planes due to the doping or oxygen deficiency. by studying the naturally occurring charge states of Cu in Cu2O and CuO, a better understanding of the relationship between structure and bonding can be achieved for the important copper oxides.
Electron Refraction of Amorphous Nanospheres
Authors: Wang YC , Chou TM , Libera M 
Published: July 2020

Abstract
The phase shift imparted to an incident high-energy electron wave in a TEM is related to the specimen’s electron-refractive properties. These, in turn, are related to the electrostatic potential and, by Fourier transform (1), to the electron scattering factors fe i(s) for the various atom species i in the specimen and scattering vectors s. The average refractive index is determined by the mean electrostatic (inner) potential, Φo, and can be modelled as Φo = (C/Ω) Σfe i(s0) [equation 1] where C = 47.878 (V-Å2) and the summation runs over all of the atoms in the unit volume Ω (2). Calculated fe i(s) data are available from the literature (e.g. 3). These calculations have only been done for neutral atoms and some fully ionized cations and anions. They do not account for electron redistribution due to covalent bonding to which Φo is quite sensitive (4).
This research is making Φo measurements using transmission electron holography. Holograms were collected using a 200keV Philips CM20 FEG TEM equipped with a non-rotatable biprism (5) and a Gatan 794 Multiscan camera.
A Direct Phasing Electron Image of Oxygen Atoms in a Ga-In-Sn-O Ceramic
Authors: Sinkler W , Marks L D , Edwards D , Mason T O 
Published: July 2020

Abstract
In solving complex inorganic structures, often the greatest challenge is to obtain good initial atom positions for Rietveld refinement using x-ray diffraction intensities. In this work, a technique is presented which combines direct phasing with HRTEM and exploits dynamical diffraction effects to obtain an image of oxygen atoms. The technique was used in the structure determination of a monoclinic (Ga0.7In0.3)2SnO5 phase to provide accurate first-guess positions for oxygen atoms for subesquent Rietveld refinement.
The solution of the cation positions of the structure relied on HRTEM images. The image in Fig. 1, taken along the crystal’s short b-axis, has a defocus of approximately -50 nm based on the locations of minima in a weak amorphous component in the power spectra of the through-focus image series. Because this is near Scherzer defocus, one expects dark areas of the image to correspond a large projected potential (making the weak phase object approximation). This was used to get successful initial cation positions for a Rietveld refinement of powder x-ray diffraction data. The final refined structure is shown in Fig. 2, including the oxygen positions.