Microscopy X-ray Research Articles

3D porous reduced graphene oxide-coated zinc anodes for highly-stable aqueous zinc-ion capacitors via electrostatic spray deposition

Zinc-ion energy storage devices are inexpensive and safe, benefitting from the abundance of Zn metal and high chemical stability. However, their electrochemical performance is poor, owing to the unstable Zn stripping/plating process of the Zn metal anode and the occurrence of side reactions. In this study, 3D porous reduced graphene oxide-coated Zn (rGO@Zn) was prepared via electrostatic spray deposition (ESD) and used as an anode for aqueous hybrid Zn-ion capacitors (ZICs). ESD is a cost-effective one-step technique that affords excellent control over the deposition morphology. Coating 3D porous rGO with a large surface area on Zn foil, resulted in a low charge transfer resistance and small voltage hysteresis (44.5 mV) with a long cycle life of over 3000 h. Moreover, the energy density improved at high rates (25 Wh kg−1 at 10,882 W kg−1) in aqueous hybrid ZICs. In-situ synchrotron transmission X-ray microscopy and optical microscopy analyses revealed that the formation of dendrites was inhibited in the as-fabricated ZICs. Furthermore, the conductive rGO on the surface of the Zn anode stabilized the electric field during the Zn stripping/plating process, and the functional groups guided the Zn2+ deposition sites, resulting in uniform Zn deposition during cycling and improved electrochemical performance.

Direct detection system for full-field nanoscale X-ray diffraction-contrast imaging

Recent developments in X-ray science provide methods to probe deeply embedded mesoscale grain structures and spatially resolve them using dark field X-ray microscopy (DFXM). Extending this technique to investigate weak diffraction signals such as magnetic systems, quantum materials and thin films prove challenging due to available detection methods and incident X-ray flux at the sample. We present a direct detection method developed in conjunction with KAImaging which focuses on DFXM studies in the hard X-ray range of 10s of keV and above capable of approaching nanoscale resolution. Additionally, we compare this direct detection scheme with routinely used scintillator-based optical detection and achieve an order of magnitude improvement in exposure times allowing for imaging of weakly diffracting ordered systems.

Rapid detection of rare events from in situX-ray diffraction data using machine learning.

High-energy X-ray diffraction methods can non-destructively map the 3D microstructure and associated attributes of metallic polycrystalline engineering materials in their bulk form. These methods are often combined with external stimuli such as thermo-mechanical loading to take snapshots of the evolving microstructure and attributes over time. However, the extreme data volumes and the high costs of traditional data acquisition and reduction approaches pose a barrier to quickly extracting actionable insights and improving the temporal resolution of these snapshots. This article presents a fully automated technique capable of rapidly detecting the onset of plasticity in high-energy X-ray microscopy data. The technique is computationally faster by at least 50 times than the traditional approaches and works for data sets that are up to nine times sparser than a full data set. This new technique leverages self-supervised image representation learning and clustering to transform massive data sets into compact, semantic-rich representations of visually salient characteristics (e.g. peak shapes). These characteristics can rapidly indicate anomalous events, such as changes in diffraction peak shapes. It is anticipated that this technique will provide just-in-time actionable information to drive smarter experiments that effectively deploy multi-modal X-ray diffraction methods spanning many decades of length scales.

On-line correlative imaging of cryo-PALM and soft X-ray tomography for identification of subcellular structures

Correlative imaging of fluorescence microscopy and soft X-ray microscopy plays a crucial role in exploring the relationship between structure and function in cellular biology. However, the current correlative imaging methods are limited either to off-line or low-resolution fluorescence imaging. In this study, we developed an integrated on-line cryogenic photoactivated localization microscopy (cryo-PALM) system at a soft X-ray microscopy station. This design eliminates some critical issues such as sample damage and complex post-correlation arising from transferring samples between different cryostages. Furthermore, we successfully achieved correlative imaging of cryopreserved near-native cells, with a resolution of about 50 nm of cryo-PALM. Therefore, the developed on-line correlation imaging platform provides a powerful tool for investigating the intricate relationship between structure and function in biological and molecular interactions, as well as in other life science disciplines.

Direct evidence from STXM analysis of enhanced oxygen storage capacity in ceria through the addition of Cu and Mg: Correlation of HT-WGS reaction performance

Here, scanning transmission X-ray microscopy (STXM) analysis was utilized to directly present visual evidence of changes in oxygen storage capacity (OSC) when small amounts of an additive were incorporated into CeO2. Specifically, the chemical map measured by STXM analysis differentiated between Cu-rich and Ce-rich areas to derive the proportion of Ce3+. Additionally, we found that the dispersion of Cu significantly influenced the formation of OSC. The findings were applied to the high-temperature water–gas shift reaction for producing high-purity hydrogen from waste-derived syngas, establishing a correlation with catalyst performance. Consequently, the CCM75 (Ce/Mg = 75/25) catalyst demonstrated the highest Cu dispersion and OSC values (6.9 %, 800.3 μmolO/gcat), and it also showed the highest CO conversion (79 % at 450 °C) and stability (−7.7 % at 450 °C after 50 h), attributed to the significant presence of active Cu. This study confirms previously reported interactions between Cu and CeO2 and uncovers the significant roles of Cu and Mg in this catalysis system, providing new understanding of the mechanisms that facilitate OSC improvement.

Multifractal Characterization of Coal Deterioration Induced by Cyclic Hydraulic Pressure Based on the Acoustic Emission Test and X-ray Microscopy

Multifractal Characterization of Coal Deterioration Induced by Cyclic Hydraulic Pressure Based on the Acoustic Emission Test and X-ray Microscopy

Cytotoxic evaluation of Dovyalis Caffra leaf extract-mediated hematite-(Fe2O3) nanoparticles for biological applications

Although hematite (Fe2O3) nanoparticles are gaining attention for biomedical purposes due to their unique properties, eco-friendly synthesis using plant extracts is being explored due to toxicity concerns of the resulting material. This study explores the use of plant extracts (Dovyalis caffra leaf extracts) for the synthesis of Fe2O3 nanoparticles alongside their cytotoxicity profile using human embryonic kidney cells (HEK293) and human cervical cancer cells (HeLa). The physicochemical properties of the prepared nanoparticles were established using x-ray diffraction (XRD) and microscopy techniques, confirming their crystalline nature and spherical morphology with minimal agglomeration. Using the MTT assay approach, the cytotoxicity profile of the nanoparticles revealed dose-dependent cytotoxic effects, with higher specificity towards cancer cells and very low toxicity towards the human cell line, suggesting safe usage as biomedical agents. While the standard drug 5-Fluorouracil possessed significantly higher cytotoxicity, its unwanted high toxicity towards normal human cells makes the Fe2O3 nanoparticles a better choice. These findings suggest the potential of Dovyalis caffra leaf extract-mediated Fe2O3 nanoparticles for biomedical applications, emphasizing their low toxicity towards normal human cells and specificity towards cancer cells.

Visualizing alpha-synuclein and iron deposition in M83 mouse model of Parkinson's disease in vivo.

Abnormal alpha-synuclein (αSyn) and iron accumulation in the brain play an important role in Parkinson's disease (PD). Herein, we aim to visualize αSyn inclusions and iron deposition in the brains of M83 (A53T) mouse models of PD in vivo. The fluorescent pyrimidoindole derivative THK-565 probe was characterized by means of recombinant fibrils and brains from 10- to 11-month-old M83 mice. Concurrent wide-field fluorescence and volumetric multispectral optoacoustic tomography (vMSOT) imaging were subsequently performed in vivo. Structural and susceptibility weighted imaging (SWI) magnetic resonance imaging (MRI) at 9.4 T as well as scanning transmission x-ray microscopy (STXM) were performed to characterize the iron deposits in the perfused brains. Immunofluorescence and Prussian blue staining were further performed on brain slices to validate the detection of αSyn inclusions and iron deposition. THK-565 showed increased fluorescence upon binding to recombinant αSyn fibrils and αSyn inclusions in post-mortem brain slices from patients with PD and M83 mice. Administration of THK-565 in M83 mice showed higher cerebral retention at 20 and 40 min post-intravenous injection by wide-field fluorescence compared to nontransgenic littermate mice, in congruence with the vMSOT findings. SWI/phase images and Prussian blue indicated the accumulation of iron deposits in the brains of M83 mice, presumably in the Fe3+ form, as evinced by the STXM results. In conclusion, we demonstrated in vivo mapping of αSyn by means of noninvasive epifluorescence and vMSOT imaging and validated the results by targeting the THK-565 label and SWI/STXM identification of iron deposits in M83 mouse brains ex vivo.

Influence of Magnetic Sublattice Ordering on Skyrmion Bubble Stability in 2D Magnet Fe5GeTe2.

The realization of above room-temperature ferromagnetism in the two-dimensional (2D) magnet Fe5GeTe2 represents a major advance for the use of van der Waals (vdW) materials in practical spintronic applications. In particular, observations of magnetic skyrmions and related states within exfoliated flakes of this material provide a pathway to the fine-tuning of topological spin textures via 2D material heterostructure engineering. However, there are conflicting reports as to the nature of the magnetic structures in Fe5GeTe2. The matter is further complicated by the study of two types of Fe5GeTe2 crystals with markedly different structural and magnetic properties, distinguished by their specific fabrication procedure: whether they are slowly cooled or rapidly quenched from the growth temperature. In this work, we combine X-ray and electron microscopy to observe the formation of magnetic stripe domains, skyrmion-like type-I, and topologically trivial type-II bubbles, within exfoliated flakes of Fe5GeTe2. The results reveal the influence of the magnetic ordering of the Fe1 sublattice below 150 K, which dramatically alters the magnetocrystalline anisotropy and leads to a complex magnetic phase diagram and a sudden change of the stability of the magnetic textures. In addition, we highlight the significant differences in the magnetic structures intrinsic to slow-cooled and quenched Fe5GeTe2 flakes.

Foam density mapping via THz imaging

Plastic foams, near-ubiquitous in everyday life and industry, show properties that depend primarily on density. Density measurement, although straightforward in principle, is not always easy. As such, while several methods are available, plastic foam industry is not yet supported with a standard technique that effectively enables to control density maps. To overcome this issue, this paper proposes Terahertz (THz) time-of-flight imaging using normal reflection measurements as a fast, relatively cheap, contactless, non-destructive and non-dangerous way to map plastic foam density, based on the expected relationship between density and refractive index. The approach is demonstrated in the case of polypropylene foams. First, the relationship between the estimated effective refractive index and the polypropylene foam density is derived by characterizing a set of carefully crafted samples having uniform density in the range 70–900 kg/m3. The obtained calibration curve subtends a linear relationship between the density and the refractive index in the range of interest. This relationship is validated against a set of test samples, whose estimated average densities are consistent with the nominal ones, with an absolute error lower than 10 kg/m3 and a percentage error on the estimate of 5%. Exploiting the calibration curve, it is possible to build quantitative images depicting the spatial distribution of the sample density. THz images are able to reveal the non-uniform density distribution of some samples, which cannot be appreciated from visual inspection. Finally, the complex spatial density pattern of a graded foam sample is characterized and quantitatively compared with the density map obtained via X-ray microscopy. The comparison confirms that the proposed THz approach successfully determines the density pattern with an accuracy and a spatial scale variability compliant with those commonly required for plastic foam density estimate.

Revisiting Li-CO2/O2 battery chemistry through the spatial distributions of discharge products and their oxidation behaviors

Li-CO2/O2 batteries present a promising strategy for CO2 conversion and energy storage, yet the complexity of discharge products poses challenges for revealing their oxidation. Here, we simulate the influences of various properties of Li2CO3 and/or Li2O2 on the decomposition pathway by comprehensively analyzing the singlet O2 (1O2) and gas components (O2 and CO2) generated during electrochemical oxidation. Our results show that no matter Li2CO3 or Li2O2, the decomposition of samples with small size and poor crystallinity produces less 1O2 and more gas product. Especially, small and poorly crystalline Li2CO3 triggers the concurrent decomposition of Li2CO3 and C, while large and highly crystalline Li2CO3 favors the solo decomposition pathway. Furthermore, the 1O2 yield can be most inhibited at a Li2CO3/Li2O2 ratio of 50 %. After clarifying the nature of Li2CO3 and/or Li2O2 oxidation, the spatial distributions of the oxygen discharge product in Li-CO2/O2 batteries were observed by scanning transmission X-ray microscopy (STXM). Li2CO3 is mainly distributed in the interior of large aggregates with high crystallinity. Poorly crystalline Li2O2 appears as small particles or coats on the surface of Li2CO3. Combined with multi-dimensional information of the discharge products and simulation results, the oxidation behaviors of the discharge products in Li-CO2/O2 batteries are reacquainted.

A survey study on arsenic speciation in coal fly ash and insights into the role of coal combustion conditions

Coal fly ashes (CFAs) are the low-density byproducts of the coal combustion process. Improper or uncontrolled CFA disposal poses significant environmental and health concerns due to the potential leaching of toxic heavy metals such as arsenic (As). Previous studies have investigated the content and speciation of As in different CFA samples, yet systematic information on As speciation in CFA with representative coal source and combustion conditions is still missing. Based on a recent survey study on the typical coal sources and combustion conditions across the U.S., this study selected 19 representative CFA samples to systematically investigate As speciation and potential correlations with these parameters. The composition, morphology, mineralogy, and As speciation of these CFA samples were characterized by complementary analytical, microscopic, and spectroscopic techniques. Synchrotron X-ray spectroscopy and microscopy analyses revealed the dominant As oxidation state to be As(V) and with strong associations to Ca, with the exception of 3 samples that had 19–51% As(III), likely due to the use of selective catalytic reduction (SCR) process. Principal component analysis was conducted to identify potential correlations of As concentration and oxidation state with parameters such as major element content, loss on ignition (LOI), average particle size, coal source, and combustion condition. Al2O3 and FeO content were found to capture a majority of the variability. Results from this study provide fundamental basis for understanding the correlations between coal source, combustion conditions, CFA characteristics, and As speciation, and providing insights for downstream beneficial utilization or disposal management.

Application of Recycled Ultrafiltration Membranes in an Aerobic Membrane Bioreactor (aMBR): A Validation Study.

A validation study using recycled ultrafiltration membranes (r-UF) on an aerobic membrane bioreactor (aMBR) was conducted for the first time. Four different polyethersulfone (PES) membranes were tested using synthetic urban wastewater (COD 0.4-0.5 g/L) during two experimental periods: (i) recycled ultrafiltration membrane (r-UF) and commercial UF membrane (molecular weight cut-off (MWCO) 150 kDa) (c-150 kDa); (ii) r-UF membrane modified by dip-coating using catechol (CA) and polyethyleneimine (PEI) (mr-UF) and c-20 kDa membrane. Permeability, fouling behavior, and permeate quality were evaluated. Extensive membrane characterization was conducted using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray (EDX), and confocal laser scanning microscopy (CLSM). Permeate quality for r-UF and mr-UF membranes was excellent and comparable to that obtained using commercial membranes under similar conditions. Additionally, r-UF and mr-UF membranes presented a steadier performance time. Additionally, r-UF membrane demonstrated less tendency to be fouled (Rf, m-1) r-UF 7.92 ± 0.57 × 1012; mr-UF 9.90 ± 0.14 × 1012, c-150 kDa 1.56 ± 0.07 × 1013 and c-20 kDa 1.25 ± 0.50 × 1013. The r-UF membrane showed an excellent antibiofouling character. Therefore, r-UF membranes can be successfully implemented for wastewater treatment in aMBR, being a sustainable and cost-effective alternative to commercial membranes that can contribute to overcome membrane fouling and membrane replacement issues.

Thermomechanical Material Characterization of Polyethylene Terephthalate Glycol with 30% Carbon Fiber for Large-Format Additive Manufacturing of Polymer Structures.

Large-format additive manufacturing (LFAM) is used to print large-scale polymer structures. Understanding the thermal and mechanical properties of polymers suitable for large-scale extrusion is needed for design and production capabilities. An in-house-built LFAM printer was used to print polyethylene terephthalate glycol with 30% carbon fiber (PETG CF30%) samples for thermomechanical characterization. Thermogravimetric analysis (TGA) shows that the samples were 30% carbon fiber by weight. X-ray microscopy (XRM) and porosity studies find 25% voids/volume for undried material and 1.63% voids/volume for dry material. Differential scanning calorimetry (DSC) shows a glass transition temperature (Tg) of 66 °C, while dynamic mechanical analysis (DMA) found Tg as 82 °C. The rheology indicated that PETG CF30% is a good printing material at 220-250 °C. Bending experiments show an average of 48.5 MPa for flexure strength, while tensile experiments found an average tensile strength of 25.0 MPa at room temperature. Comparison with 3D-printed PLA and PETG from the literature demonstrated that LFAM-printed PETG CF30% had a comparative high Young's modulus and had similar tensile strength. For design purposes, prints from LFAM should consider both material choice and print parameters, especially when considering large layer heights.

Formulation and Characterization of Silibinin Entrapped Nano-Liquid Crystals for Activity against Aβ1-42 Neurotoxicity in In-Vivo Model.

Silibinin (SIL) Encapsulated Nanoliquid Crystalline (SIL-NLCs) particles were prepared to study neuroprotective effect against amyloid beta (Aβ1-42) neurotoxicity in Balb/c mice model. Theses NLCs were prepared through hot emulsification and probe sonication technique. The pharmacodynamics was investigatigated on Aβ1-42 intracerebroventricular (ICV) injected Balb/c mice. The particle size, zeta potential and drug loading were optimized to be 153 ± 2.5nm, -21mV, and 8.2%, respectively. Small angle X-ray (SAXS) and electron microscopy revealed to crystalline shape of SIL-NLCs. Thioflavin T (ThT) fluroscence and circular dichroism (CD) techniquewere employed to understand monomer inhibition effect of SIL-NLCs on Aβ1-4. In neurobehavioral studies, SIL-NLCs exhibited enhanced mitigation of memory impairment induced on by Aβ1-42 in T-maze and new object recognition test (NORT). Whereas biochemical and histopathological estimation of brain samples showed reduction in level of Aβ1-42 aggregate, acetylcholine esterase (ACHE) and reactive oxygen species (ROS). SIL-NLCs treated animal group showed higher protection against Aβ1-42 toxicity compared to free SIL and Donopezil (DPZ). Therefore SIL-NLCs promises great prospect in neurodegenerative diseases such as Alzheimer's disease.

Formation of zinc carbonate phases on dissolving calcite, aragonite, and vaterite in acidic aqueous solutions

Calcium carbonate (CaCO3) minerals serve as a major sink to retain metal ions through mineral-water interfacial reactions in which the capacity and long-term stability of contaminant uptake are influenced by coupled dissolution and precipitation reactions of both primary and secondary carbonate minerals (i.e., mineral replacement). Notably, recent studies of calcite reactivity in acidic solutions containing high levels of metal ions demonstrated complex behavior under conditions of sustained disequilibrium. We explored the reactivity of three CaCO3 polymorphs (calcite, aragonite, and vaterite) with acidic Zn2+-containing aqueous solutions using a suite of imaging techniques including optical and scanning electron microscopies, synchrotron-based micro X-ray fluorescence, and transmission X-ray microscopy. Zn uptake by calcite occurred through a two-step process: the formation of a thin layer of the zinc precipitate on the substrate surface followed by the growth of fibrous and radiating hydrozincite particles from the layer. In contrast, Zn uptake by aragonite occurred by mineral replacement where the secondary Zn carbonate phase preserved the external morphology of the original crystal (i.e., a pseudomorph). The replacement of vaterite by hydrozincite occurred within the confined space beneath the porous shell of vaterite, signifying that the primary mechanism driving Zn carbonate precipitation was chemical exchange through the pores. When multiple CaCO3 polymorphs coexisted, the replacement of aragonite and vaterite occurred preferentially over that of calcite. These results demonstrate the distinct morphological and mineralogical controls over the reactivities of calcium carbonate minerals with Zn2+ under acidic conditions.

Substrates for Soft X-Ray Microscopy Based on Si3N4 Membranes

Substrates for Soft X-Ray Microscopy Based on Si3N4 Membranes

In Situ Studies of Cu Catalyzed CO2 Electro-Reduction by Soft X-ray Scanning Transmission X-ray Microscopy and Soft X-ray Spectro-Ptychography

In Situ Studies of Cu Catalyzed CO2 Electro-Reduction by Soft X-ray Scanning Transmission X-ray Microscopy and Soft X-ray Spectro-Ptychography

Facile Synthesis and Characterization of Zirconia Nanoparticles in Dental Applications

Scientists and dentists use tiny particles called ZrO2/Nps (Zirconia Nanoparticles) in medicine. In addition, zirconia particles are commonly used in the realm of medicine and dentistry. They are ideal for tooth structure because of their beneficial properties. The objective of this research is to prepare zirconium oxide nanoparticles in a simple and easy way. Nano-zirconium oxide is prepared using the co-precipitation method. The produced powder was diagnosed using tools like X-ray diffraction, microscopy, and spectroscopy, which also analyzed its properties such as X-ray spectroscopy and density measurement. The XRD results confirmed that the powder product has high purity. The crystal size range is 27.97nm. The results match the (JCPDS (ZrO2) sheet No.79-1769). The EDX test revealed the presence of the following elements (Zr–O). The test of SEM (Scanning Electron Microscope) show that the particles nearly spherical and the size was 74.03nm. The Zr–O stretching modes and the Zr–O2–Zr bending modes were confirmed by the FTIR (Fourier transform infrared). The density of ZrO2/Np was measured several times and determined it to be (5.07±0.12 g/cm3).

Epifluorescence microscopy study of a quadruple node of triple junctions of grain boundaries in a Eu2+-decorated highly textured composite of (Cl, Br)(K, Rb) and I(K, Rb) solid solutions.

The structural nature and geometry, as well as the lattice-relative orientation, of an arrangement of crystal defects in a highly textured Eu2+-doped composite of two alkali-halide solid solutions was studied by epifluorescence microscopy (EFM) using the doping ion as a fluorochrome. A three-dimensional reconstruction and a skeleton type model, as built from a sequence of EFM images of different optical cross-sections of this arrangement, are presented. Structurally, this arrangement is a quadruple node (QN) of triple junctions of grain boundaries. The QN core geometry is that of a tetragonal tristetrahedron (TTTH), centred at the QN site, whose tetrahedron vertices and edges are on the QN triple junctions and grain boundaries, respectively, whereas the tristetrahedron tetragonal axis is nearly parallel to the lattice [001]-axis. The measured values of the angles between triple junctions and between the grain boundaries forming them are reported. The distinct chemical compositions of the composite solid solutions are discussed to be responsible, in last instance, for the tristetrahedron departure from a cubic configuration. Collaterally, certain families of translationally periodic almost-parallel (TPAP)-wall-like regions which consist of TPAP-columns of TPAP-spindle-like singularities, as well as certain zigzag arrays of columns of this like, existing into the QN grains, are reported to be observed. Three-dimensional reconstructions of typical individuals of these families and arrays as well as of their constituent parts are presented and geometrically analysed. These families and arrays are discussed to be families of tilt subboundaries, whose constituent dislocations are decorated by cylindrical second-phase europium di-halide precipitates, and regularly faceted tilt subboundaries, respectively. Crystal growing and sample preparation, composite structural characterisation by powder and single-slab X-ray diffraction (PXRD and SSXRD, respectively), microscopy and fluorescence-cube unit optics, image processing, electronic three-dimensional reconstruction and measuring methodologies, are all described in detail.