X-ray Microbeam Research Articles

Impact of microscopic In fluctuations on the optical properties of InxGa1-xN blue light-emitting diodes assessed by low-energy X-ray fluorescence mapping using synchrotron radiation

Among the III-nitride semiconductors, InxGa1-xN is a key material for visible optical devices such as light-emitting diodes (LEDs), laser diodes, and solar cells. Light emission is achieved via electron-hole recombination within the InxGa1-xN layer. When InxGa1-xN-based blue LEDs were first commercialized, the high probability of electron-hole radiative recombination despite the presence of numerous threading dislocations was a mystery. Extensive studies have proposed that carrier localization in nanoscopic potential fluctuations due, for example, to the immiscibility between InN and GaN or random alloy fluctuations is a key mechanism for the high emission efficiency. In actual LED devices, not only nanoscopic potential fluctuations but also microscopic ones exist within the InxGa1-xN quantum well light-emitting layers. Herein we map the synchrotron radiation microbeam X-ray fluorescence of InxGa1-xN blue LEDs at a sub-micron level. To acquire weak signals of In, Ar, which is in the air and has a fluorescent X-ray energy similar to that of In, is evacuated from the sample chamber by He purge. As a result, we successfully visualize the spatial In distribution of InxGa1-xN layer nondestructively and present good agreement with optical properties. Additionally, we demonstrate that unlike nanoscopic fluctuations, microscopic In compositional fluctuations do not necessarily have positive effects on device performance. Appropriately controlling both nanoscopic and microscopic fluctuations at the same time is necessary to achieve supreme device performance.

Microbeam X-ray fluorescence mapping of Cu and Fe in human prostatic carcinoma cell lines using synchrotron radiation

Cancer is a worldwide public health problem and prostate cancer continues to be one of the most common fatal cancers in men. Copper plays an important role in the aetiology and growth of tumours however, whether intratumoral copper is actually elevated in prostate cancer patients has not been established. Iron, an important trace element, plays a vital function in oxygen metabolism, oxygen uptake, and electron transport in mitochondria, energy metabolism, muscle function, and hematopoiesis. The X-ray microfluorescence technique (μXRF) is a rapid and non-destructive method of elemental analysis that provides useful elemental information about samples without causing damage or requiring extra sample preparations. This study investigated the behavior of cells in spheroids of human prostate cells, tumour cell line (DU145) and normal cell line (RWPE-1), after supplementation with zinc chloride by 24 hours using synchrotron X-ray microfluorescence (μSRXRF). The measurements were performed with a standard geometry of 45º of incidence, excited by a white beam using a pixel of 25 μm and a time of 300 ms/pixel at the XRF beamline at the Synchrotron Light.

Basis for the Bauschinger effect in copper single crystals: changes in the long-range internal stress with reverse deformation

The long-range internal stresses (LRIS) associated with the Bauschinger effect were investigated using synchrotron X-ray microbeam diffraction and reversed deformation experiments. [100]-oriented Cu single crystals were deformed in compression to approximately − 0.3 true strain, followed by tension to a strain of approximately + 0.02. Two conclusions are arrived at from this work: First, the LRIS are confirmed in this work to be small relative to the applied stress both before and after reversal. Second, the LRIS persist after 2% reversed strain despite a significant drop in the overall dislocation density by dynamic recovery. This appears to satisfy the necessary condition for LRIS to significantly contribute to a Bauschinger effect in materials. The pronounced Bauschinger effect in Cu is probably best rationalized by a combination of both the LRIS and the Orowan–Sleeswyk model that relies on a non-uniform distribution of dislocation obstacles without a substantial LRIS.

МІКРОПРОМЕНЕВЕ РЕНТГЕНОГРАФУВАННЯ ЯК ОДИН ІЗ НАЙСУЧАСНІШИХ ПРИЙОМІВ АРТИКУЛЯЦІЙНИХ ДОСЛІДЖЕНЬ

The article substantiates the necessity of phonetic, in particular articulation, researches. The role of articulatory research in the study of the nature of sound units and their significance for linguistics and practical use are determined. The preconditions for studying the sound system of the language with the help of experimental techniques are specified. The history of occurrence and development of experi- mental phonetic researches in Ukraine and in the world is analyzed. The main methods of articulation research, including types of X-ray examination as one of the most important articulatory techniques, are considered. There are brought to the light the history and procedure of film-roentgenography with its implementation in Ukrainian linguistics. A number of tasks performed by experimental phonetics, as well as the possibility of applying its results in different fields of knowledge are outlined. The article is focused on X-ray microbeam – one of the most contemporary types of X-ray re- search, which was created by the Japanese scientist Osama Fujimura in the second half of the last century. The history of creating the device for such studies is traced, the procedure of collecting articu- lation information (preparation for recording, the placement of tracking beads, type of the articulated material and tasks set forth) is described. The main advantages of X-ray microbeam in comparison with other methods are determined: it gives information about all the sounds of human speech, does not distort the pronunciation, causes minimal harm to health, allows studying large masses of information quickly and automatically. At the and, the conclusion about the feasibility of usage X-ray microbeam in experimental phonet- ics is made. It is confired the significance of such a method, which lies in the interdisciplinary type of research, the generation of new knowledge in the field of phonetics and the addition of existing infor- mation with the help of the latest technologies.

Inverse-phase composite zone plate providing deeper focus than the normal diffraction-limited depth of X-ray microbeams.

A novel type of zone plate (ZP), termed an inverse-phase composite ZP, is proposed to gain a deeper focus than the standard diffraction-limited depth of focus, with little reduction in spatial resolution. The structure is a combination of an inner ZP functioning as a conventional phase ZP and an outer ZP functioning with third-order diffraction with opposite phase to the inner ZP. Two-dimensional complex amplitude distributions neighboring the focal point were calculated using a wave-optical approach of diffraction integration with a monochromatic plane-wave illumination, where one dimension is the radial direction and the other dimension is the optical-axis direction. The depth of focus and the spatial resolution were examined as the main focusing properties. Two characteristic promising cases regarding the depth of focus were found: a pit-intensity focus with the deepest depth of focus, and a flat-intensity focus with deeper depth of focus than usual ZPs. It was found that twice the depth of focus could be expected with little reduction in the spatial resolution for 10 keV X-ray energy, tantalum zone material, 84 nm minimum fabrication zone width, and zone thickness of 2.645 µm. It was also found that the depth of focus and the spatial resolution were almost unchanged in the photon energy range from 8 to 12 keV. The inverse-phase composite ZP has high potential for use in analysis of practical thick samples in X-ray microbeam applications.

Hierarchical radial structure of polyacrylonitrile precursor formed during the wet-spinning process.

Electron probe micro-analysis (EPMA), micro-beam wide angle X-ray diffraction (Micro-beam WAXD), micro-Raman and nano-infrared (nano-IR) spectroscopy were performed to characterize the hierarchical radial structure within polyacrylonitrile (PAN) fibre which was obtained by the wet-spinning method, including morphology, aggregation structure and molecular chain conformation. The results indicated that along the radial direction of the PAN fibre, the skin layer reflects denser morphology compared to the core region. The crystallinity, d-spacing of the (100) Miller plane and crystalline orientation in PAN fibres were gradually decreased from the skin layer to the central part, while the crystalline size shows opposite distribution tendency which was affected by the diffusion depending on the coagulation environment. As to the molecular chain structure, PAN chains tend to keep the helical conformation rather than planar zigzag conformation and packed more orderly in the skin layer of fibres.

Structural Analysis of Coating Film on Human Skin using Microbeam X-ray Scattering

Structural Analysis of Coating Film on Human Skin using Microbeam X-ray Scattering

A Functional Immune System Is Required for the Systemic Genotoxic Effects of Localized Irradiation

Nontargeted effects of ionizing radiation, by which unirradiated cells and tissues are also damaged, are a relatively new paradigm in radiobiology. We recently reported radiation-induced abscopal effects (RIAEs) in normal tissues; namely, DNA damage, apoptosis, and activation of the local and systemic immune responses in C57BL6/J mice after irradiation of a small region of the body. High-dose-rate, synchrotron-generated broad beam or multiplanar x-ray microbeam radiation therapy was used with various field sizes and doses. This study explores components of the immune system involved in the generation of these abscopal effects. The following mice with various immune deficiencies were irradiated with the microbeam radiation therapy beam: (1) SCID/IL2γR-/- (NOD SCID gamma, NSG) mice, (2) wild-type C57BL6/J mice treated with an antibody-blocking macrophage colony-stimulating factor 1 receptor, which depletes and alters the function of macrophages, and (3) chemokine ligand 2/monocyte chemotactic protein 1 null mice. Complex DNA damage (ie, DNA double-strand breaks), oxidatively induced clustered DNA lesions, and apoptotic cells in tissues distant from the irradiation site were measured as RIAE endpoints and compared with those in wild-type C57BL6/J mice. Wild-type mice accumulated double-strand breaks, oxidatively induced clustered DNA lesions, and apoptosis, enforcing our RIAE model. However, these effects were completely or partially abrogated in mice with immune disruption, highlighting the pivotal role of the immune system in propagation of systemic genotoxic effects after localized irradiation. These results underline the importance of not only delineating the best strategies for tumor control but also mitigating systemic radiation toxicity.

Spatially fractionated proton minibeams.

Extraordinary normal tissue response to highly spatially fractionated X-ray beams has been explored for over 25 years. More recently, alternative radiation sources have been developed and utilized with the aim to evoke comparable effects. These include protons, which lend themselves well for this endeavour due to their physical depth dose characteristics as well as corresponding variable biological effectiveness. This paper addresses the motivation for using protons to generate spatially fractionated beams and reviews the technological implementations and experimental results to date. This includes simulation and feasibility studies, collimation and beam characteristics, dosimetry and biological considerations as well as the results of in vivo and in vitro studies. Experimental results are emerging indicating an extraordinary normal tissue sparing effect analogous to what has been observed for synchrotron generated X-ray microbeams. The potential for translational research and feasibility of spatially modulated proton beams in clinical settings is discussed.

Synchrotron microbeam X-ray scattering study of the crystallite orientation in the spherulites of isotactic poly(butene-1) crystallized isothermally at different temperatures

The hierarchical structure of spherulites grown isothermally from a melt was investigated for isotactic poly(butene-1) (it-PB-1) by analyzing wide-angle and small-angle X-ray scattering data measured simultaneously at various positions of the spherulites using a synchrotron X-ray microbeam technique. In square-shaped spherulites (hedrites) grown at 103 °C, the chain axis stands along the direction normal to the spherulite surface and the a and b axes of the original form II crystal direct in parallel to the square edges. On the other hand, for round-shape spherulites grown at 98 °C, the chain axis lies tangentially along the circle of the round spherulite surface. These spatial geometries, revealed by the X-ray microbeam method, have confirmed previously-reported results that were qualitatively derived from 2-dimensional polarized FTIR imaging experiments [J Phys Chem B. 2016;120:4689]. Surprisingly, only a 5 °C difference in the isothermal crystallization temperature gives rise to remarkably different hierarchical structures of it-PB-1, as clarified by the X-ray microbeam technique. Conducting polymers were synthesized via in situ polymerization, using nanoclay bentonite sodium and its modified form. The polymer nanoclay modified form showed enhanced solubility compared to the original polymers and improved thermal stability, along with higher corrosion inhibition efficiency and aggregation-induced emission with luminescence dependent on the aggregate structure.

Interaction between Al and atomic layer deposited (ALD) ZrN under high-energy heavy ion irradiation

Uranium-molybdenum (U-Mo) particles dispersed in an aluminum matrix is the most promising candidate fuel to convert high-power research and test reactors in Europe from using high-enriched to using low-enriched fuel. However, chemical interaction between the U-Mo and the Al matrix leads to undesirable fuel behavior. Zirconium nitride (ZrN) is used as a diffusion barrier between the U-Mo fuel particles and the Al matrix. To understand the potential microstructural evolution of ZrN during irradiation, a high-energy heavy ion (84 MeV Xe) irradiation experiment was performed on atomic layer deposited (ALD) nanocrystalline ZrN deposited on an Al plate. A fluence of 1.86×1017 ions/cm2, or 90.3 dpa was reached during this experiment. Both analytic transmission electron microscopy (TEM) and synchrotron microbeam X-ray diffraction (μXRD) techniques were utilized to investigate the kinetics of radiation-induced grain growth of ZrN at various radiation doses based on the Williamson-Hall analyses. The grain growth kinetics can be described by a power law expression, Dn−D0n=Kϕ, with n = 5.1. The Al-ZrN interaction products (Al3Zr and AlN) created by radiation-induced ballistic mixing/radiation-enhanced diffusion and their corresponding formation mechanism were determined from electron diffraction and elemental composition analysis. These experimental results were confirmed by first principle thermodynamic density functional theory (DFT) calculations. The results from this ion irradiation study were also compared to in-pile irradiation data from physical vapor deposited (PVD) ZrN samples for a comprehensive evaluation of the interaction between Al and ZrN and its influence on diffusion barrier performance.

High-intensity x-ray microbeam for macromolecular crystallography using silicon kinoform diffractive lenses.

Macromolecular crystallography often requires focused high-intensity x-ray beams for solving challenging protein structures from micrometer-sized crystals using current synchrotron radiation sources. The design of optical focusing schemes for hard x-rays showing high efficiency and flexibility in beam size is therefore continuously pursued. Here, we present an innovative solution based on a two-stage demagnification of the undulator source for photon energies from 6keV to 19keV, commissioned at the X10SA beamline of the Swiss Light Source, where a secondary source is imaged by two crossed silicon kinoform x-ray diffractive lenses with 75nm outermost zone width. A source-size limited spot with a size of 4.8 μm×1.7 μm(h×v,FWHM) and flux of 7.5×1010 photons/s at 12.4keV is demonstrated at the sample position.

Study on bone quality in the human mandible-Alignment of biological apatite crystallites.

The importance of considering bone quality during oral implant treatment is increasingly being recognized. Assessment of bone quality in response to changes in the jaw bone is extremely important when planning treatment. The present study analyzed biological apatite (BAp) crystallites, a bone quality factor, in order to investigate crystallographic anisotropy in dentate and edentulous human mandibles. Using mandibular samples from Japanese adult cadavers, a region of interest was established comprising cortical bone in the central incisors. Samples were classified into five morphological categories based on the extent of bone resorption. Bone mineral density (BMD) was measured and diffraction intensity ratios were calculated using a microbeam X-ray diffraction system. While no differences were observed in BMD, differences were observed in BAp crystallite alignment between the measurement points. In the alveolar region, samples with residual alveolar bone showed strong alignment in the occlusal direction, while samples with marked alveolar bone resorption had preferential alignment in the mesiodistal direction. The present findings suggest that tooth loss and the extent of alveolar bone resorption affects bone quality in the mandible. © 2018 Wiley Periodicals, Inc. J. Biomed. Mater. Res. Part B: 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 838-846, 2019.

X-ray fluorescence imaging

Over the past two decades, numerous X-ray micro-beam studies have been published addressing the nondestructive investigation of chemical element distribution in condensed heterogeneous media. Based on this literature, some aspects of the field are discussed in this paper, including X-ray focusing methods and various elemental imaging techniques: scanning and confocal X-ray fluorescence microscopy, full-field X-ray fluorescence microscopy, X-ray fluorescence tomography, and prospects for combining X-ray fluorescence imaging with other physical methods rested on using synchrotron radiation.

Relationship between twisting phenomenon and structural discontinuity of stacked lamellae in the spherulite of poly(ethylene adipate) as studied by the synchrotron X-ray microbeam technique

Wide-angle and small-angle X-ray scattering measurements were performed simultaneously using an X-ray beam 1 μm in size to detect the inner structure of a spherulite of poly(ethylene adipate) [PEA, –(O(CH2)2OCO(CH2)4CO–)n–]. The lamellae were found to twist periodically by 180° in the area between the neighboring bright rings observed in the polarized optical microscope image of the spherulite. However, as known from the discontinuity between the repeated lamellar zones discovered by Woo et al. (Macromolecules, 45:1375–1383, 2012), the twisted lamellae must not be assumed to be continuously twisted long plates spreading out over the spherulite. Rather, these lamellae should be considered to have limited areas of ~7 μm in length along the radial direction and with disconnected end zones. The present X-ray scattering data revealed the structural relation between the repeated arrays of the disconnected lamellar blocks and the 180° twisting phenomenon, which occurs only in the finite and disconnected flat-on lamellar zones. Designer supramolecular polymers are a growing field of polymer materials. The designability and flexibility in their structures and functionality have attracted a great deal of attention in polymer science, as well as in supramolecular chemistry. These polymeric structures are formed from one or more molecular components via reversible bonds; therefore, monomeric and polymeric states are in equilibrium on the relevant experimental timescale. The dynamic nature of supramolecular polymers in terms of chain lifetime and conformational flexibility are determined by external conditions. This adaptivity can result in stimuli-responsive structures and properties. This article describes the use of our host–guest structures based on a calix[5]arene, a bisporphyrin, and a self-assembled capsule in the synthesis of supramolecular polymers.

Strain partition and rupture analysis of notched tensile multilayered steel specimens

Multilayered steel composites consisting of alternating martensitic and austenite layers were successfully fabricated with a combination of high strength and ductility. In situ SEM tensile experiments were performed to investigate the fracture processes. Results indicated that the martensitic layer distributed between two ductile austenite layers has better deformation ability, and the dimple fracture mode dominated the fracture of the whole specimen. In situ synchrotron microbeam X-ray diffraction experiments were carried out to study the microscopic deformation in austenitic layer and martensitic layer ahead of notch root under incremental tensile loading. Results indicated that for austenite layer, the maximum strain is located in the middle of the layer at the lower applied load. When at the higher applied load, larger strain is concentrated on the notch root. For martensitic layer, uniform strain is distributed at the region at the lower applied load, with increasing the applied load, small strain appears in the middle of martensitic layer. However, the variation in the strain in the martensitic layer is relatively smaller, which is actually affected by both the notch and the ferrite content in the martensitic layer. The changing trends of the strain in the austenite layer and martensitic layer can still show the better combination of brittle martensitic phase and ductile austenite phase.

Contribution of the tongue tip retraction in the articulation of high vowels

This study shows that the retraction of the tongue tip contributes to the raising of the tongue body in the articulation of high vowels /i/ and /u/ by using qualitative simulations of tongue deformation by using a biomechanical 3D tongue model of Artisynth (Lloyd et al. 2012) and the analysis of tongue configuration in X-ray microbeam data (Westbury 1994). The simulations qualitatively replicated the tongue shapes at the temporal mid-point of /i/ and /u/ in rtMRI data by manipulating the activation values of tongue muscles in Artisynth. The results show that the tongue tip retraction helps to raise the tongue body higher in both /i/ and /u/. In the simulations of /i/, the tongue tip retraction raises the tongue body even without moving the tongue body. The results of x-ray microbeam analysis confirm those findings of simulations. The mixed linear regression model of tongue configurations in the tasks of sentence and paragraph production shows that more tongue tip retraction (a shorter horizontal distance between two anterior tongue pellets) significantly correlates with a higher position of the tongue body (higher one between two posterior tongue pellets) in both /i/ and /u/ and the correlation is stronger in /i/ than in /u/.

Microbeam X-ray fluorescence and X-ray absorption spectroscopic analysis of Chinese blue-and-white kraak porcelain dating from the Ming dynasty

Microbeam X-ray fluorescence (XRF) spectroscopy is applied, next to an art-historical analysis, to determine the time and place of origin of Chinese blue-and-white porcelain. In the performed experiments, two groups of kraak porcelain samples (A and B) have been analyzed with XRF spectroscopy to obtain quantitative data, (trace) elemental distributions and fingerprints within different regions of interest. The outcome was processed with Principal Component Analysis (PCA), and with the obtained results it was possible to conclude that the two groups show similar elemental fingerprints and were manufactured in the same time period with a comparable use of raw materials. Additionally, X-ray absorption spectroscopy (XAS) measurements have been performed on the pigment layer, confirming the use of Cobalt Blue as an underglaze pigment.

Chemical state and atomic scale environment of nickel in the corrosion layer of irradiated Zircaloy-2 at a burn-up around 45 MWd/kg

Zircaloy-2 is used as fuel cladding in commercial boiling water reactors (BWR). A limiting factor for fuel longevity is the waterside corrosion of the cladding during in-service reactor operation and associated hydrogen pickup to the alloy. It is well known that the alloying elements (such as Cr, Fe, Ni etc.) including intermetallic precipitates (also termed as SPP) distribution influences both the oxidation process and hydrogen uptake evolution in this material. This paper reports an experimental investigation on the atomic scale microstructure of nickel-containing intermetallic particles with an emphasis on the oxidation and nickel-dissolution of SPP, and a combined experimental and computational study of solute nickel located in the corroded zirconium oxide microstructure. An irradiated cladding sample, taken from a BWR fuel rod, was prepared for the analysis using electron probe microanalysis (EPMA) and synchrotron-based micro-beam X-ray techniques (μXRF, μXRD and μXAS). The results show that the Ni-bearing SPP in the oxide layer are neither fully dissolved nor entirely oxidized at the given burn-up of the sample investigated. Conversely, all solute nickel present in the corroded layer is mostly oxidized and has an apparent homogeneous Ni2+ distribution. By analyzing the μXAS spectra measured at the Ni absorption edge, we have obtained quantitative structural information about both irradiated SPP and the Ni coordination environment in the corrosion layer. There exists strong structural disorder in intermetallic Ni-bearing SPP as also evidenced by μXRD study. The basic structure away from SPP in the oxide area is composed of oxidized nickel atoms adjacent to oxygen vacancies. Finally, first-principles density functional theory (DFT) calculations have been used to discern the nickel speciation in zirconium oxide microstructure that is complementary to the multitude of experimental information. From this joint theoretical and experimental approach, significant insights into the structural specificity of Ni2+ ions in monoclinic ZrO2, electronic factors governing the electron transport processes in the corrosion layer, and the apparent influence of nickel on the hydrogen ingress behavior in Zircaloy-2 are obtained.

Compound Refractive Lens Optics for Microbeam X-ray Diffraction Measurements at BL13XU in SPring-8

Compound Refractive Lens Optics for Microbeam X-ray Diffraction Measurements at BL13XU in SPring-8