| 1. |
- Aboulfadl, Hisham, et al.
(författare)
-
Microstructural Characterization of Sulfurization Effects in Cu(In,Ga)Se2 Thin Film Solar Cells
- 2019
-
Ingår i: Microscopy and Microanalysis. - : CAMBRIDGE UNIV PRESS. - 1435-8115 .- 1431-9276. ; 25:2, s. 532-538
-
Tidskriftsartikel (refereegranskat)abstract
- Surface sulfurization of Cu(In,Ga)Se 2 (CIGSe) absorbers is a commonly applied technique to improve the conversion efficiency of the corresponding solar cells, via increasing the bandgap towards the heterojunction. However, the resulting device performance is understood to be highly dependent on the thermodynamic stability of the chalcogenide structure at the upper region of the absorber. The present investigation provides a high-resolution chemical analysis, using energy dispersive X-ray spectrometry and laser-pulsed atom probe tomography, to determine the sulfur incorporation and chemical re-distribution in the absorber material. The post-sulfurization treatment was performed by exposing the CIGSe surface to elemental sulfur vapor for 20 min at 500°C. Two distinct sulfur-rich phases were found at the surface of the absorber exhibiting a layered structure showing In-rich and Ga-rich zones, respectively. Furthermore, sulfur atoms were found to segregate at the absorber grain boundaries showing concentrations up to ∼7 at% with traces of diffusion outwards into the grain interior.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Bhuiyan, Iftekhar Uddin, et al.
(författare)
-
Microstructure of Bentonite in Iron Ore Green Pellets
- 2014
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 20:1, s. 33-41
-
Tidskriftsartikel (refereegranskat)abstract
- Sodium-activated calcium bentonite is used as a binder in iron ore pellets and is known to increase strength of both wet and dry iron ore green pellets. In this article, the microstructure of bentonite in magnetite pellets is revealed for the first time using scanning electron microscopy. The microstructure of bentonite in wet and dry iron ore pellets, as well as in distilled water, was imaged by various imaging techniques (e.g., imaging at low voltage with monochromatic and decelerated beam or low loss backscattered electrons) and cryogenic methods (i.e., high pressure freezing and plunge freezing in liquid ethane). In wet iron ore green pellets, clay tactoids (stacks of parallel primary clay platelets) were very well dispersed and formed a voluminous network occupying the space available between mineral particles. When the pellet was dried, bentonite was drawn to the contact points between the particles and formed solid bridges, which impart strength to the solid compact.
|
|
| 7. |
- Boll, Torben, 1979, et al.
(författare)
-
Interfaces in Oxides Formed on NiAlCr Doped with Y, Hf, Ti, and B
- 2017
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 23:2, s. 396-403
-
Tidskriftsartikel (refereegranskat)abstract
- This study applies atom probe tomography (APT) to analyze the oxide scales formed on model NiAlCr alloys doped with Hf, Y, Ti, and B. Due to its ability to measure small amounts of alloying elements in the oxide matrix and its ability to quantify segregation, the technique offers a possibility for detailed studies of the dopant's fate during high-temperature oxidation. Three model NiAlCr alloys with different additions of Hf, Y, Ti, and B were prepared and oxidized in O2 at 1,100°C for 100 h. All specimens showed an outer region consisting of different spinel oxides with relatively small grains and the protective Al2O3-oxide layer below. APT analyses focused mainly on this protective oxide layer. In all the investigated samples segregation of both Hf and Y to the oxide grain boundaries was observed and quantified. Neither B nor Ti were observed in the alumina grains or at the analyzed interfaces. The processes of formation of oxide scales and segregation of the alloying elements are discussed. The experimental challenges of the oxide analyses by APT are also addressed.
|
|
| 8. |
- Buxhuku, Mika, et al.
(författare)
-
The Determination of Rotation Axis in the Rotation Electron Diffraction Technique
- 2013
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 19:5, s. 1276-1280
-
Tidskriftsartikel (refereegranskat)abstract
- Methods to determine the rotation axis using the rotation electron diffraction technique are described. A combination of rotation axis tilt, beam tilt, and simulated experimental diffraction patterns with nonintegers zone axis has been used. Accurate knowledge of the crystallographic direction of the incident beam for deducing the excitation error of reflections simultaneously near Bragg positions is essential in quantitative electron diffraction. Experimental patterns from CoP3 are used as examples.
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Dahmen, Tim, et al.
(författare)
-
Matched Backprojection Operator for Combined Scanning Transmission Electron Microscopy Tilt- and Focal Series
- 2015
-
Ingår i: Microscopy and Microanalysis. - : Cambridge University Press. - 1431-9276 .- 1435-8115. ; 21:3, s. 725-738
-
Tidskriftsartikel (refereegranskat)abstract
- Combined tilt- and focal series scanning transmission electron microscopy is a recently developed method to obtain nanoscale three-dimensional (3D) information of thin specimens. In this study, we formulate the forward projection in this acquisition scheme as a linear operator and prove that it is a generalization of the Ray transform for parallel illumination. We analytically derive the corresponding backprojection operator as the adjoint of the forward projection. We further demonstrate that the matched backprojection operator drastically improves the convergence rate of iterative 3D reconstruction compared to the case where a backprojection based on heuristic weighting is used. In addition, we show that the 3D reconstruction is of better quality.
|
|
| 12. |
- Dehlinger, Aurelie, et al.
(författare)
-
Laboratory Soft X-Ray Microscopy with an Integrated Visible-Light Microscope-Correlative Workflow for Faster 3D Cell Imaging
- 2020
-
Ingår i: Microscopy and Microanalysis. - : Cambridge University Press (CUP). - 1431-9276 .- 1435-8115. ; 26:6, s. 1124-1132
-
Tidskriftsartikel (refereegranskat)abstract
- Laboratory transmission soft X-ray microscopy (L-TXM) has emerged as a complementary tool to synchrotron-based TXM and high-resolution biomedical 3D imaging in general in recent years. However, two major operational challenges in L-TXM still need to be addressed: a small field of view and a potentially misaligned rotation stage. As it is not possible to alter the magnification during operation, the field of view in L-TXM is usually limited to a few tens of micrometers. This complicates locating areas and objects of interest in the sample. Additionally, if the rotation axis of the sample stage cannot be adjusted prior to the experiments, an efficient workflow for tomographic imaging cannot be established, as refocusing and sample repositioning will become necessary after each recorded projection. Both these limitations have been overcome with the integration of a visible-light microscope (VLM) into the L-TXM system. Here, we describe the calibration procedure of the goniometer sample stage and the integrated VLM and present the resulting 3D imaging of a test sample. In addition, utilizing this newly integrated VLM, the extracellular matrix of cryofixed THP-1 cells (human acute monocytic leukemia cells) was visualized by L-TXM for the first time in the context of an ongoing biomedical research project.
|
|
| 13. |
- Dong, Yan, et al.
(författare)
-
Atom Probe Tomography Interlaboratory Study on Clustering Analysis in Experimental Data Using the Maximum Separation Distance Approach
- 2019
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 25:2, s. 356-366
-
Tidskriftsartikel (refereegranskat)abstract
- We summarize the findings from an interlaboratory study conducted between ten international research groups and investigate the use of the commonly used maximum separation distance and local concentration thresholding methods for solute clustering quantification. The study objectives are: to bring clarity to the range of applicability of the methods; identify existing and/or needed modifications; and interpretation of past published data. Participants collected experimental data from a proton-irradiated 304 stainless steel and analyzed Cu-rich and Ni-Si rich clusters. The datasets were also analyzed by one researcher to clarify variability originating from different operators. The Cu distribution fulfills the ideal requirements of the maximum separation method (MSM), namely a dilute matrix Cu concentration and concentrated Cu clusters. This enabled a relatively tight distribution of the cluster number density among the participants. By contrast, the group analysis of the Ni-Si rich clusters by the MSM was complicated by a high Ni matrix concentration and by the presence of Si-decorated dislocations, leading to larger variability among researchers. While local concentration filtering could, in principle, tighten the results, the cluster identification step inevitably maintained a high scatter. Recommendations regarding reporting, selection of analysis method, and expected variability when interpreting published data are discussed.
|
|
| 14. |
- Dorri, Mahrokh, et al.
(författare)
-
Characterization of Amorphous Oxide Nano-Thick Layers on 316L Stainless Steel by Electron Channeling Contrast Imaging and Electron Backscatter Diffraction
- 2016
-
Ingår i: Microscopy and Microanalysis. - : CAMBRIDGE UNIV PRESS. - 1431-9276 .- 1435-8115. ; 22:5, s. 997-1006
-
Tidskriftsartikel (refereegranskat)abstract
- Characterization of the topmost surface of biomaterials is crucial to understanding their properties and interactions with the local environment. In this study, the oxide layer microstructure of plasma-modified 316L stainless steel (SS316L) samples was analyzed by a combination of electron backscatter diffraction and electron channeling contrast imaging using low-energy incident electrons. Both techniques allowed clear identification of a nano-thick amorphous oxide layer, on top of the polycrystalline substrate, for the plasma-modified samples. A methodology was developed using Monte Carlo simulations combined with the experimental results to estimate thickness of the amorphous layer for different surface conditions. X-ray photoelectron spectroscopy depth profiles were used to validate these estimations.
|
|
| 15. |
- Eriksson, Gustav, 1994, et al.
(författare)
-
Silica-embedded Gold Nanoparticles Analyzed by Atom Probe Tomography
- 2024
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; In Press
-
Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles are utilized in a multitude of applications due to their unique properties. Consequently, characterization of nanoparticles is crucial, and various methods have been employed in these pursuits. One such method is Atom Probe Tomography (APT). However, existing sample preparation techniques for APT generally involve embedding of the nanoparticles in a matrix different from their environment in solutions or at solid-liquid interfaces. In this work, we demonstrate a methodology based on silica embedding and explore how it can be utilized to form a matrix for nanoparticles suitable for APT analysis. Through chemisorption to a surface, gold nanoparticles were densely packed, ensuring a high probability of encountering at least one particle in the APT analyses. The nanoparticle-covered surface was embedded in a silica film, replacing the water and thus making this method suitable for studying nanoparticles in their hydrated state. The nanoparticle's silver content and its distribution, originating from the nanoparticle synthesis, could be identified in the APT analysis. Sodium clusters, possibly originating from the sodium citrate used to stabilize the particles in solution, were observed on the nanoparticle surfaces. This indicates the potential for silica embedding to be used for studying ligands on nanoparticles in their hydrated state. Graphical Abstract
|
|
| 16. |
- Ewels, Philip, et al.
(författare)
-
A Complete Overhaul of the Electron Energy-Loss Spectroscopy and X-Ray Absorption Spectroscopy Database : eelsdb.eu
- 2016
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 22:3, s. 717-724
-
Tidskriftsartikel (refereegranskat)abstract
- The electron energy-loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) database has been completely rewritten, with an improved design, user interface, and a number of new tools. The database is accessible at https://eelsdb.eu/ and can now be used without registration. The submission process has been streamlined to encourage spectrum submissions and the new design gives greater emphasis on contributors' original work by highlighting their papers. With numerous new filters and a powerful search function, it is now simple to explore the database of several hundred EELS and XAS spectra. Interactive plots allow spectra to be overlaid, facilitating online comparison. An application-programming interface has been created, allowing external tools and software to easily access the information held within the database. In addition to the database itself, users can post and manage job adverts and read the latest news and events regarding the EELS and XAS communities. In accordance with the ongoing drive toward open access data increasingly demanded by funding bodies, the database will facilitate open access data sharing of EELS and XAS spectra.
|
|
| 17. |
- Fager, Cecilia, 1990, et al.
(författare)
-
Optimization of FIB-SEM Tomography and Reconstruction for Soft, Porous, and Poorly Conducting Materials
- 2020
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 26:4, s. 837-845
-
Tidskriftsartikel (refereegranskat)abstract
- Tomography using a focused ion beam (FIB) combined with a scanning electron microscope (SEM) is well-established for a wide range of conducting materials. However, performing FIB-SEM tomography on ion- and electron-beam-sensitive materials as well as poorly conducting soft materials remains challenging. Some common challenges include cross-sectioning artifacts, shadowing effects, and charging. Fully dense materials provide a planar cross section, whereas pores also expose subsurface areas of the planar cross-section surface. The image intensity of the subsurface areas gives rise to overlap between the grayscale intensity levels of the solid and pore areas, which complicates image processing and segmentation for three-dimensional (3D) reconstruction. To avoid the introduction of artifacts, the goal is to examine porous and poorly conducting soft materials as close as possible to their original state. This work presents a protocol for the optimization of FIB-SEM tomography parameters for porous and poorly conducting soft materials. The protocol reduces cross-sectioning artifacts, charging, and eliminates shadowing effects. In addition, it handles the subsurface and grayscale intensity overlap problems in image segmentation. The protocol was evaluated on porous polymer films which have both poor conductivity and pores. 3D reconstructions, with automated data segmentation, from three films with different porosities were successfully obtained.
|
|
| 18. |
- Fedorova, Irina, et al.
(författare)
-
Analyzing Boron in 9-12% Chromium Steels Using Atom Probe Tomography
- 2019
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 25:2, s. 462-469
-
Tidskriftsartikel (refereegranskat)abstract
- Microscopy Society of America 2019. Small additions of boron can remarkably improve the long-term creep resistance of 9-12% Cr steels. The improvement has been attributed to boron segregation to grain boundaries during quenching, and subsequent boron incorporation into certain families of precipitates during tempering. However, the detailed mechanisms are not yet fully understood. Atom probe tomography (APT) is an excellent technique for gaining insights into boron distribution, however, in order to acquire accurate analysis of boron in 9-12% Cr steels using APT, there are several key challenges. In order to better understand and address these challenges, we developed a novel method for site-specific APT specimen preparation, which enables convenient preparation of specimens containing specifically selected grain boundaries positioned approximately perpendicular to the axis of the APT tip. Additionally, when analyzing boron at boundaries and in carbides (as diluted solute) and borides, a widening of the profile of boron distribution compared to other elements was repeatedly observed. This phenomenon is particularly analyzed and discussed in light of the evaporation field of different elements. Finally, the possible effects of detector dead-time on quantitative analysis of boron in metal borides are discussed. A simple method using 10B correction was used to obtain good quantification.
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
- Fostad, Ida G., et al.
(författare)
-
Identification of Objective Morphometric Markers of Xerostomia in the Oral Mucosa Epithelium with In Vivo Confocal Microscopy
- 2017
-
Ingår i: Microscopy and Microanalysis. - : CAMBRIDGE UNIV PRESS. - 1431-9276 .- 1435-8115. ; 23:1, s. 88-96
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to determine whether the morphology of the oral mucosa epithelium (OME) of patients with xerostomia differ from patients without xerostomia. In total, 34 patients with dry eye disease (DED) with or without xerostomia were examined at The Norwegian Dry Eye Disease Clinic with in vivo confocal microscopy of the lower lip. In addition, age- and gender-matched healthy controls (HC) were included. DED patients with xerostomia had a higher superficial to deep backscatter ratio compared with DED patients without xerostomia (p=0.002) and HC (p=0.001). Regression analysis demonstrated that this ratio was related to xerostomia independently of gender and age (pamp;lt;0.001). Sensitivity and specificity of detecting xerostomia were 0.78 and 0.85, respectively, when using a superficial to deep backscatter ratio cut-off value of 0.995 (p=0.004). The mean nucleus to cytosol backscatter ratio in the superficial OME was lower in patients with xerostomia than in those without xerostomia (p=0.034). In vivo confocal microscopy is a potential tool for evaluating the oral cavity and to assess changes in the OME associated with xerostomia, objectively and quantitatively. The cause of the increased backscatter in the superficial OME in xerostomia, however, remains to be elucidated.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Jansson, Anna, 1985, et al.
(författare)
-
Novel Method for Controlled Wetting of Materials in the Environmental Scanning Electron Microscope
- 2013
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 19:1, s. 30-37
-
Tidskriftsartikel (refereegranskat)abstract
- Environmental scanning electron microscopy has been extensively used for studying the wetting properties of different materials. For some types of investigation, however, the traditional ways of conducting in situ dynamic wetting experiments do not offer sufficient control over the wetting process. Here, we present a novel method for controlled wetting of materials in the environmental scanning electron microscope (ESEM). It offers improved control of the point of interaction between the water and the specimen and renders it more accessible for imaging. It also enables the study of water transport through a material by direct imaging. The method is based on the use of a piezo-driven nanomanipulator to bring a specimen in contact with a water reservoir in the ESEM chamber. The water reservoir is established by local condensation on a Peltier-cooled surface. A fixture was designed to make the experimental setup compatible with the standard Peltier cooling stage of the microscope. The developed technique was successfully applied to individual cellulose fibers, and the absorption and transport of water by individual cellulose fibers were imaged.
|
|
| 25. |
- Jansson, Anna, 1985, et al.
(författare)
-
Novel Method for Visualizing Water Transport Through Phase-Separated Polymer Films
- 2014
-
Ingår i: Microscopy and Microanalysis. - : Oxford University Press (OUP). - 1435-8115 .- 1431-9276. ; 20:2, s. 394-406
-
Tidskriftsartikel (refereegranskat)abstract
- Drug release from oral pharmaceutical formulations can be modified by applying a polymeric coating film with controlled mass transport properties. Interaction of the coating film with water may crucially influence its composition and permeability to both water and drug. Understanding this interaction between film microstructure, wetting, and mass transport is important for the development of new coatings. We present a novel method for controlled wetting of polymer coating films in an environmental scanning electron microscope, providing direct visual information about the processes occurring as the film goes from dry to wet. Free films made of phase-separated blends of water-insoluble ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) were used as a model system, and the blend ratio was varied to study the effect on the water transport properties. Local variations in water transport through the EC/HPC films were directly observed, enabling the immediate analysis of the structure-mass transport relationships. The leaching of HPC could be studied by evaporating water from the films in situ. Significant differences were observed between films of varying composition. The method provides a valuable complement to the current approach of making distinct diffusion and microscopy experiments for studying the dynamic interaction of polymer films with water.
|
|
| 26. |
- Johansen, Marcus, 1994, et al.
(författare)
-
Best Practices for Analysis of Carbon Fibers by Atom Probe Tomography
- 2022
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 28:4, s. 1092 -1101
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon fiber technology drives significant development in lightweight and multifunctional applications. However, the microstructure of carbon fibers is not completely understood. A big challenge is to obtain the distribution of heteroatoms, for instance nitrogen, with high spatial resolution in three dimensions. Atom probe tomography (APT) has the potential to meet this challenge, but APT of carbon fibers is still relatively unexplored. We performed APT on three types of carbon fibers, including one high modulus type and two intermediate modulus types. Here, we present the methods to interpret the complex mass spectra of carbon fibers, enhance the mass resolution, and increase the obtained analysis volume. Finally, the origin of multiple hit events and possible methods to mitigate multiple hit events are also discussed. This paper provides guidance for future APT studies on carbon fibers, and thus leads the way to a deeper understanding of the microstructure, and consequently advancements in wide applications of carbon fibers.
|
|
| 27. |
- Klemm, Anna H., et al.
(författare)
-
Tracking Microscope Performance : A Workflow to Compare Point Spread Function Evaluations Over Time
- 2019
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 25:3, s. 699-704
-
Tidskriftsartikel (refereegranskat)abstract
- Routine system checks are essential for supervising the performance of an advanced light microscope. Recording and evaluating the point spread function (PSF) of a given system provides information about the resolution and imaging. We compared the performance of fluorescent and gold beads for PSF recordings. We then combined the open-source evaluation software PSFj with a newly developed KNIME pipeline named PSFtracker to create a standardized workflow to track a system's performance over several measurements and thus over long time periods. PSFtracker produces example images of recorded PSFs, plots full-width-half-maximum (FWHM) measurements over time and creates an html file which embeds the images and plots, together with a table of results. Changes of the PSF over time are thus easily spotted, either in FWHM plots or in the time series of bead images which allows recognition of aberrations in the shape of the PSF. The html file, viewed in a local browser or uploaded on the web, therefore provides intuitive visualization of the state of the PSF over time. In addition, uploading of the html file on the web allows other microscopists to compare such data with their own.
|
|
| 28. |
- Koeck, Philip J. B.
(författare)
-
Alternative Forward Models for Imaging Thick Specimens in Transmission Electron Microscopy
- 2023
-
Ingår i: Microscopy and Microanalysis. - : Oxford University Press (OUP). - 1431-9276 .- 1435-8115. ; 29:3, s. 1071-1076
-
Tidskriftsartikel (refereegranskat)abstract
- I have investigated two different forward models for image formation in transmission electron microscopy of thick specimens, the 3DCtf model, which introduces a defocus gradient in the linear approximation, and the multislice model. An important result is that the 3DCtf model does not seem to be compatible with the multislice image formation model. A second very useful finding is that the exit wave in the multislice model has an imaginary part, which, in first-order approximation, is a pure projection of the specimen and is not affected by the defocus gradient. The defocus gradient only comes into play in real valued and higher-order imaginary terms. If the multislice model is closer to reality than the 3DCtf-model, then the best way to retrieve the specimen projection for thicker specimens should be a procedure for retrieving the exit wave's imaginary term, for example using images recorded at different defocus values.
|
|
| 29. |
- Krivanek, Ondrej L., et al.
(författare)
-
Toward Single Mode, Atomic Size Electron Vortex Beams
- 2014
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 20:3, s. 832-836
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a practical method of producing a single mode electron vortex beam suitable for use in a scanning transmission electron microscope (STEM). The method involves using a holographic "fork" aperture to produce a row of beams of different orbital angular momenta, as is now well established, magnifying the row so that neighboring beams are separated by about 1 mu m, selecting the desired beam with a narrow slit, and demagnifying the selected beam down to 1-2 angstrom in size. We show that the method can be implemented by adding two condenser lenses plus a selection slit to a straight-column cold-field emission STEM. It can also be carried out in an existing instrument, the monochromated Nion high-energy-resolution monochromated electron energy-loss spectroscopy-STEM, by using its monochromator in a novel way. We estimate that atom-sized vortex beams with <= 20 pA of current should be attainable at 100-200 keV in either instrument.
|
|
| 30. |
- Kuang, Qie, et al.
(författare)
-
A Refined Single-Particle Reconstruction Procedure to Process Two-Dimensional Crystal Images from Transmission Electron Microscopy
- 2015
-
Ingår i: Microscopy and Microanalysis. - : Cambridge University Press. - 1431-9276 .- 1435-8115. ; 21:4, s. 876-85
-
Tidskriftsartikel (refereegranskat)abstract
- Single-particle reconstruction (SPR) and electron crystallography (EC), two major applications in electron microscopy, can be used to determine the structure of membrane proteins. The three-dimensional (3D) map is obtained from separated particles in conventional SPR, but from periodic unit cells in EC. Here, we report a refined SPR procedure for processing 2D crystal images. The method is applied to 2D crystals of melibiose permease, a secondary transporter in Escherichia coli. The current procedure is improved from our previously published one in several aspects. The "gold standard Fourier shell correlation" resolution of our final reconstruction reaches 13 A, which is significantly better than the previously obtained 17 A resolution. The choices of different refinement parameters for reconstruction are discussed. Our refined SPR procedure could be applied to determine the structure of other membrane proteins in small or locally distorted 2D crystals, which are not ideal for EC.
|
|
| 31. |
- Kördel, Mikael, et al.
(författare)
-
Biological Laboratory X-ray Microscopy
- 2018
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 24:S2, s. 346-347
-
Tidskriftsartikel (refereegranskat)
|
|
| 32. |
|
|
| 33. |
- Lazar, Isac, et al.
(författare)
-
Diffusion Bonding 321-Grade Stainless Steel : Failure and Multimodal Characterization
- 2024
-
Ingår i: Microscopy and Microanalysis. - : Oxford University Press. - 1431-9276 .- 1435-8115.
-
Tidskriftsartikel (refereegranskat)abstract
- Vacuum diffusion-bonded printed circuit heat exchangers are an attractive choice for the high-temperature, high-pressure demands of next-generation energy applications. However, early reports show that the high-temperature materials desired for these applications suffer from poor bond strengths due to precipitation at the bond line, preventing grain boundary migration. In this study, a diffusion bond of the high-temperature stainless steel grade 321H is investigated, and poor mechanical properties are found to be caused by Ti(C, N) precipitation at the bond line. Through in situ studies, it is found that Ti diffuses from the bulk to the mating surfaces at high temperatures. The Ti subsequently precipitates and, for the first time, an interaction between Ti(C, N) and Al/Mg-oxide precipitates at the bond line is observed, where Ti(C, N) nucleates on the oxides forming a core-shell structure. The results indicate that small amounts of particular alloying elements can greatly impact diffusion bond quality, prompting further research into the microstructural evolution that occurs during bonding conditions.
|
|
| 34. |
|
|
| 35. |
- Lindgren, Kristina, 1989, et al.
(författare)
-
On the Analysis of Clustering in an Irradiated Low Alloy Reactor Pressure Vessel Steel Weld
- 2017
-
Ingår i: Microscopy and Microanalysis. - : Cambridge University Press. - 1435-8115 .- 1431-9276. ; 23:2, s. 376-384
-
Tidskriftsartikel (refereegranskat)abstract
- Radiation induced clustering affects the mechanical properties, that is the ductile to brittle transition temperature (DBTT), of reactor pressure vessel (RPV) steel of nuclear power plants. The combination of low Cu and high Ni used in some RPV welds is known to further enhance the DBTT shift during long time operation. In this study, RPV weld samples containing 0.04 at% Cu and 1.6 at% Ni were irradiated to 2.0 and 6.4×10 23 n/m 2 in the Halden test reactor. Atom probe tomography (APT) was applied to study clustering of Ni, Mn, Si, and Cu. As the clusters are in the nanometer-range, APT is a very suitable technique for this type of study. From APT analyses information about size distribution, number density, and composition of the clusters can be obtained. However, the quantification of these attributes is not trivial. The maximum separation method (MSM) has been used to characterize the clusters and a detailed study about the influence of the choice of MSM cluster parameters, primarily on the cluster number density, has been undertaken.
|
|
| 36. |
- Lindgren, Kristina, 1989, et al.
(författare)
-
The Nanostructure of the Oxide Formed on Fe-10Cr-4Al Exposed in Liquid Pb
- 2022
-
Ingår i: Microscopy and Microanalysis. - : Cambridge University Press (CUP). - 1435-8115 .- 1431-9276. ; 28:4, s. 1321 -1334
-
Tidskriftsartikel (refereegranskat)abstract
- An Fe-10Cr-4Al alloy containing reactive elements developed for application in high-temperature liquid lead environments was analyzed after exposure in 600 and 750°C lead with dissolved oxygen for 1,000-2,000 h. Atom probe tomography, transmission electron microscopy, and X-ray scattering were all used to study the protective oxide formed on the surface. Exposure at 750°C resulted in a 2-μm thick oxide, whereas the 600°C exposure resulted in a 100-nm thick oxide. Both oxides were layered, with an Fe-Al spinel on top, and an alumina layer toward the metal. In the 600°C exposed material, there was a Cr-rich oxide layer between the spinel and the alumina. Metallic lead particles were found in the inner and middle parts of the oxide, related to pores. The combination of the experimental techniques, focusing on atom probe tomography, and the interpretations that can be done, are discussed in detail.
|
|
| 37. |
- MacArthur, Katherine E., et al.
(författare)
-
Optimizing Experimental Conditions for Accurate Quantitative Energy-Dispersive X-ray Analysis of Interfaces at the Atomic Scale
- 2021
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 27:3, s. 528-542
-
Tidskriftsartikel (refereegranskat)abstract
- The invention of silicon drift detectors has resulted in an unprecedented improvement in detection efficiency for energy-dispersive X-ray (EDX) spectroscopy in the scanning transmission electron microscope. The result is numerous beautiful atomic-scale maps, which provide insights into the internal structure of a variety of materials. However, the task still remains to understand exactly where the X-ray signal comes from and how accurately it can be quantified. Unfortunately, when crystals are aligned with a low-order zone axis parallel to the incident beam direction, as is necessary for atomic-resolution imaging, the electron beam channels. When the beam becomes localized in this way, the relationship between the concentration of a particular element and its spectroscopic X-ray signal is generally nonlinear. Here, we discuss the combined effect of both spatial integration and sample tilt for ameliorating the effects of channeling and improving the accuracy of EDX quantification. Both simulations and experimental results will be presented for a perovskite-based oxide interface. We examine how the scattering and spreading of the electron beam can lead to erroneous interpretation of interface compositions, and what approaches can be made to improve our understanding of the underlying atomic structure.
|
|
| 38. |
- Matthews, Bethany E., et al.
(författare)
-
Micro- and Nanoscale Surface Analysis of Late Iron Age Glass from Broborg, a Vitrified Swedish Hillfort
- 2023
-
Ingår i: Microscopy and Microanalysis. - : Oxford University Press. - 1431-9276 .- 1435-8115. ; 29:1, s. 50-68
-
Tidskriftsartikel (refereegranskat)abstract
- Archaeological glasses with prolonged exposure to biogeochemical processes in the environment can be used to understand glass alteration, which is important for the safe disposal of vitrified nuclear waste. Samples of mafic and felsic glasses with different chemistries, formed from melting amphibolitic and granitoid rocks, were obtained from Broborg, a Swedish Iron Age hillfort. Glasses were excavated from the top of the hillfort wall and from the wall interior. A detailed microscopic, spectroscopic, and diffraction study of surficial textures and chemistries were conducted on these glasses. Felsic glass chemistry was uniform, with a smooth surface showing limited chemical alteration (<150 nm), irrespective of the position in the wall. Mafic glass was heterogeneous, with pyroxene, spinel, feldspar, and quartz crystals in the glassy matrix. Mafic glass surfaces in contact with topsoil were rougher than those within the wall and had carbon-rich material consistent with microbial colonization. Limited evidence for chemical or physical alteration of mafic glass was found; the thin melt film that coated all exposed surfaces remained intact, despite exposure to hydraulically unsaturated conditions, topsoil, and associated microbiome for over 1,500 years. This supports the assumption that aluminosilicate nuclear waste glasses will have a high chemical durability in near-surface disposal facilities.
|
|
| 39. |
- Melin, Lisa, et al.
(författare)
-
Evaluation of X-ray Microanalysis for Characterization of Dental Enamel
- 2014
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 20:1, s. 257-267
-
Tidskriftsartikel (refereegranskat)abstract
- Elemental analysis of dental hard tissues is of importance and especially regarding enamel with developmental disturbances. The aim of this study was to evaluate XRMA analysis of bovine enamel in a scanning electron microscope (SEM) with different coatings using a low-vacuum technique. The buccal surface of mandibular bovine incisors was polished flat and one third was coated with carbon, one third with gold, leaving one third uncoated for XRMA analysis in a SEM equipped with an EDS microanalysis system. The elements oxygen, sodium, magnesium, phosphorous, chlorine, potassium and calcium were analysed using their respective characteristic K X-ray series. Comparisons were also made with analyses of glass produced by fusion of the bovine enamel, which showed that oxygen analyses using the K X-ray series are reliable and preferable to calculating oxygen by stoichiometry for natural enamel. For the gold-coated and uncoated analyses, carbon was also measured using the K X-ray series. Small area (10 micron square) analyses in VP-SEM mode with low vacuum, without any coating midway between 40 micron wide gold lines 140 microns apart to avoid build-up of electrostatic charge is the preferred method, especially if C is included in the analysis. The analyses of bovine enamel are sufficiently reproducible to be regarded as quantitative for all elements except carbon.
|
|
| 40. |
- Melin, Lisa, et al.
(författare)
-
XRMA and ToF-SIMS Analysis of Normal and Hypomineralized Enamel.
- 2015
-
Ingår i: Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada. - 1435-8115 .- 1431-9276. ; 21:2, s. 407-21
-
Tidskriftsartikel (refereegranskat)abstract
- Molar incisor hypomineralization (MIH) is a developmental disturbance of the enamel. This study presents analyses of hypomineralized and normal enamel in first molar teeth diagnosed with MIH, utilizing time-of-flight secondary ion mass spectrometry area analyses and X-ray microanalysis of area and spot profiles in uncoated samples between gold lines which provide electrical conductivity. Statistical analysis of mean values allows discrimination of normal from MIH enamel, which has higher Mg and lower Na and P. Inductive analysis using complete data sets for profiles from the enamel surface to the enamel-dentin junction found that Mg, Cl and position in the profile provide useful discrimination criteria. Element profiles provide a visual complement to the inductive analysis and several elements also provide insight into the development of both normal and MIH enamel. The higher Mg content and different Cl profiles of hypomineralized enamel compared with normal enamel are probably related to a relatively short period during the development of ameloblasts between birth and the 1st year of life.
|
|
| 41. |
|
|
| 42. |
|
|
| 43. |
- Oudbashi, Omid, 1978, et al.
(författare)
-
The Metallic Sounds: A Microanalytical Study on the Production of Armenian Church Bells from Iran
- 2023
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 29:3, s. 1298-1306
-
Tidskriftsartikel (refereegranskat)abstract
- There are a considerable number of church bells in museums, examples include the museum of the Vank Cathedral and the Treasury of Armenian Music in New Julfa, both located in Isfahan, Iran. These objects were collected from different Armenian churches and cathedrals in Iran and were dated to ca. 400-100 years ago. Due to the long history of Armenians in Iran and their important role in its cultural and architectural development, study of the production technologies they utilized is a subject of interest for art historians and scientists. Three metallic bells from the Treasury of Armenian Music in New Julfa were selected for a multianalytical study to investigate their manufacturing methods, using micro-XRF, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), and metallography techniques. The results showed that the bells were produced with a binary tin bronze alloy with 13 to 20 wt% of tin, classified as either low-tin or high-tin bronze, depending on the concentration. The analysis showed a two-phase cast microstructure consisting of the α solid solution with significant amounts of interdendritic α + δeutectoid. The results also indicate that the bells are cast first, but some evidence of complementary thermomechanical operations is visible in their microstructure.
|
|
| 44. |
|
|
| 45. |
|
|
| 46. |
- Pettersson, Henrik, 1975, et al.
(författare)
-
A Method for Producing Site-Specific TEM Specimens from Low Contrast Materials with Nanometer Precision
- 2013
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 19:1, s. 73-78
-
Tidskriftsartikel (refereegranskat)abstract
- A method that enables high precision extraction of transmission electron microscope (TEM) specimens in low contrast materials has been developed. The main idea behind this work is to produce high contrast markers on both sides of and close to the area of interest. The markers are filled during the depositing of the protective layer. The marker material can be of either Pt or C depending on which one gives the highest contrast. It is thereby possible to distinguish the location of the area of interest during focused ion beam (FIB) milling and ensure that the TEM sample is extracted precisely at the desired position. This method is generally applicable and enables FIB/scanning electron microscope users to make high quality TEM specimens from small features and low contrast materials without a need for special holders. We explain the details of this method and illustrate its potential by examples from three different types of materials.
|
|
| 47. |
- Polzer, S., et al.
(författare)
-
Automatic identification and validation of planar collagen organization in the aorta wall with application to abdominal aortic aneurysm
- 2013
-
Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 19:6, s. 1395-1404
-
Tidskriftsartikel (refereegranskat)abstract
- Arterial physiology relies on a delicate three-dimensional (3D) organization of cells and extracellular matrix, which is remarkably altered by vascular diseases like abdominal aortic aneurysms (AAA). The ability to explore the micro-histology of the aorta wall is important in the study of vascular pathologies and in the development of vascular constitutive models, i.e., mathematical descriptions of biomechanical properties of the wall. The present study reports and validates a fast image processing sequence capable of quantifying collagen fiber organization from histological stains. Powering and re-normalizing the histogram of the classical fast Fourier transformation (FFT) is a key step in the proposed analysis sequence. This modification introduces a powering parameter w, which was calibrated to best fit the reference data obtained using classical FFT and polarized light microscopy (PLM) of stained histological slices of AAA wall samples. The values of w = 3 and 7 give the best correlation (Pearson's correlation coefficient larger than 0.7, R 2 about 0.7) with the classical FFT approach and PLM measurements. A fast and operator independent method to identify collagen organization in the arterial wall was developed and validated. This overcomes severe limitations of currently applied methods like PLM to identify collagen organization in the arterial wall.
|
|
| 48. |
|
|
| 49. |
- Rashidi, Masoud, 1987, et al.
(författare)
-
Atom probe study of MX to Z-phase transformation in Z-phase strengthened 12%Cr steels
- 2017
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 23, s. 360-365
-
Tidskriftsartikel (refereegranskat)abstract
- In creep resistant Z-phase strengthened 12% Cr steels, MX to Z-phase transformation plays an important role in achieving a fine distribution of Z-phase precipitates for creep strengthening. Atom probe tomography was employed to investigate the phase transformation in a Nb-based Z-phase strengthened trial steel. Using iso-concentration surfaces with different concentration values, and subtracting the matrix contribution enabled us to reveal the core-shell structure of the transient precipitates between MX and Z-phase. It was shown that Z-phase forms by diffusion of Cr into NbN upon ageing, and Z-phase has a composition corresponding to Cr1+xNb1-xN with x=0.08.
|
|
| 50. |
- Rashidi, Masoud, 1987, et al.
(författare)
-
Core-Shell Structure of Intermediate Precipitates in a Nb-Based Z-Phase Strengthened 12% Cr Steel
- 2017
-
Ingår i: Microscopy and Microanalysis. - 1435-8115 .- 1431-9276. ; 23:2, s. 360-365
-
Tidskriftsartikel (refereegranskat)abstract
- In creep resistant Z-phase strengthened 12% Cr steels, MX (M=Nb, Ta, or V, and X=C and/or N) to Z-phase (CrMN, M=Ta, Nb, or V) transformation plays an important role in achieving a fine distribution of Z-phase precipitates for creep strengthening. Atom probe tomography was employed to investigate the phase transformation in a Nb-based Z-phase strengthened trial steel. Using iso-concentration surfaces with different concentration values, and subtracting the matrix contribution enabled us to reveal the core-shell structure of the transient precipitates between MX and Z-phase. It was shown that Z-phase forms by diffusion of Cr into NbN upon ageing, and Z-phase has a composition corresponding to Cr1+xNb1-xN with x=0.08.
|
|
