Synchrotron Radiation-based X-ray Research Articles

A Mechanism Study of Structural Transition of Lithium Vanadium Phosphate during the 1st Charge/Discharge in Comparison to Ti-Doped One

Battery is one of the most attractive energy storage systems for its usefulness in energy conversion in these days. A great attention has been paid to the Li-ion batteries, and a lot of attempts to develop the system exhibiting higher energy density and higher safety have been tried for many years. However, the safety of Li-ion battery has been problems continuously while the energy density has developed largely. The safety issues of Li-ion battery generally come from thermal runaway, mainly derived from oxygen evolution from cathode materials. Phosphate materials including frames of PO4 polyanions such as LiFePO4 are regarded as a suitable cathode material in Li-ion battery in terms of the point of view. Lithium vanadium phosphate (LVP) has high expectations as a cathode material because of its higher operating voltage (~3.6V) and theoretical capacity(197mAh/g) compared to LiFePO4. While monoclinic LVP has a higher energy density, large hysteresis comes from asymmetric charge/discharge profile, and capacity fading are the main problems when three lithium ions are extracted by raising the voltage up to 4.8V. To overcome these limitations, fine studies about the mechanism have been carried out by a few groups. Although the mechanism studies were carried out by L. Nazar group about structural transition [1] and by Lee and Park about the possible pathway of lithium ion in the structure [2], representatively, the reasons for capacity fading on LVP should be studied more. In this work, we investigated the structural changes of LVP during the first charge and discharge process of voltage window of 3.0V to 4.8V by using Galvanostatic Intermittent Titration Technique (GITT), synchrotron radiation-based X-ray Absorption Spectroscopy (XAS) and in situ X-ray diffraction (XRD). The irreversible structural transitions between charge and discharge process are one of the possible reason for the capacity fading. Also, we conducted comparison study on the electrochemical and structural properties between LVP and Li3Ti0.03V1.97(PO4)3/graphene (LVP-Ti) to overcome limitations of LVP. In situ XRD patterns show four consecutive two-phase transitions on LVP during the charge process. During the reinsertion of lithium ion, the patterns of LVP look like a combined process of single solid solution and two-phase transitions between full charged LVP (FC-LVP) and Li2V2(PO4)3 (Li2 phase) without forming Li1V2(PO4)3. In GITT data, a two phase transition behavior which was previously reported as a solid solution behavior during the Li-ion insertion from full charged LVP to Li2 phase in the discharge process is observed. From these data, it can be said that transforming behavior from FC-LVP to Li2 phase is closer to two-phase reaction. In LVP-Ti case, the charge capacity was 185.84 mAh/g and the discharge capacity was 171.20 mAh/g in the first cycle, which were higher than those of LVP, 178.84 mAh/g and 162.99 mAh/g. And in situ XRD patterns show four consecutive two-phase transitions as in LVP. During the phase transition in charge/discharge, LVP-Ti faces less lattice mismatch than LVP, resulting in better electrochemical performance, and this phenomenon is originated from smaller particle size and enduring strain. The XAS result shows that the XANES peaks of LVP-Ti change gradually which is in line with the XRD result as same as in LVP case. However, the larger peak area of the pre-edge for LVP-Ti suggesting that more electrons were released upon charging. This means that the higher capacities of LVP-Ti is contributed by further utilization of the V redox reaction. [1] Yin, S-C., Hiltrud Grondey, Pierre Strobel, M. Anne, and Linda F. Nazar. "Electrochemical property: structure relationships in monoclinic Li3-yV2(PO4)3." Journal of the American Chemical Society 125, no. 34 (2003): 10402-10411. [2] Lee, S., & Park, S. S. (2012). Atomistic simulation study of monoclinic Li3V2(PO4)3 as a cathode material for lithium ion battery: structure, defect chemistry, lithium ion transport pathway, and dynamics. The Journal of Physical Chemistry C, 116(48), 25190-25197.

An Overview on the Local Atomic Displacements and Electronic Structures in BiS2/BiSe2-Based Superconductors

Superconductivity with layered structure has attracted intensive research interests due to their exotic superconducting properties. In 2012, a new family of BiS2-based superconductor with their desired layered structure has been discovered. Recently, the isostructural superconductor with the substitution of Se for all S ions in BiS2-based compounds is recognized as the BiSe2-based superconductors. To date, enormous efforts were dedicated to explore the physical properties of this new family. Among them, synchrotron radiation-based X-ray absorption spectroscopy (XAS) contributed significantly to the understanding of local atomic structure and the electronic structure of BiS2/BiSe2-based systems. This article reviewed the progresses in the study of the new BiS2/BiSe2-based materials revealed by the unique technique XAS, including the determination of valence state, local atomic displacements, as well as the different structural distortion between BiS2-based and BiSe2-based systems. The superconductivity of BiS2- and BiSe2-based system is indeed intimately related to valence states and local atomic displacements. Further development of microscopic mechanism of superconductivity in BiS2/BiSe2-based materials requires synergetic endeavors integrating new experimental, numerical, and theoretical techniques.

In vitro and in vivo evaluations of nanocrystalline Zn-doped carbonated hydroxyapatite/alginate microspheres: zinc and calcium bioavailability and bone regeneration.

Background: Zinc-doped hydroxyapatite has been proposed as a graft biomaterial for bone regeneration. However, the effect of zinc on osteoconductivity is still controversial, since the release and resorption of calcium, phosphorus, and zinc in graft-implanted defects have rarely been studied.Methods: Microspheres containing alginate and either non-doped carbonated hydroxyapatite (cHA) or nanocrystalline 3.2 wt% zinc-doped cHA (Zn-cHA) were implanted in critical-sized calvarial defects in Wistar rats for 1, 3, and 6 months. Histological and histomorphometric analyses were performed to evaluate the volume density of newly formed bone, residual biomaterial, and connective tissue formation. Biomaterial degradation was characterized by transmission electron microscopy (TEM) and synchrotron radiation-based X-ray microfluorescence (SR-µXRF), which enabled the elemental mapping of calcium, phosphorus, and zinc on the microsphere-implanted defects at 6 months post-implantation.Results: The bone repair was limited to regions close to the preexistent bone, whereas connective tissue occupied the major part of the defect. Moreover, no significant difference in the amount of new bone formed was found between the two microsphere groups. TEM analysis revealed the degradation of the outer microsphere surface with detachment of the nanoparticle aggregates. According to SR-µXRF, both types of microspheres released high amounts of calcium, phosphorus, and zinc, distributed throughout the defective region. The cHA microsphere surface strongly adsorbed the zinc from organic constituents of the biological fluid, and phosphorus was resorbed more quickly than calcium. In the Zn-cHA group, zinc and calcium had similar release profiles, indicating a stoichiometric dissolution of these elements and non-preferential zinc resorption.Conclusions: The nanometric size of cHA and Zn-cHA was a decisive factor in accelerating the in vivo availability of calcium and zinc. The high calcium and zinc accumulation in the defect, which was not cleared by the biological medium, played a critical role in inhibiting osteoconduction and thus impairing bone repair.

The role of cupric ions in the oxidative dissolution process of marmatite: A dependence on Cu2+ concentration

Cupric ions (Cu2+) play an important role in the oxidative dissolution process of marmatite in an acidic environment. In this work, dissolution experiments and numerous analytical techniques were utilized to investigate the role of Cu2+ in the oxidative dissolution process of marmatite in sulfuric acid. The dissolution experiments showed that the role of Cu2+ is significantly dependent on its concentration. A low Cu2+ concentration (0.25–750 mg/L) can significantly accelerate marmatite dissolution, and a relatively high Cu2+ concentration (above 1000 mg/L) can hinder marmatite dissolution. Element analysis, synchrotron radiation-based X-ray diffraction (SR-XRD) and Raman spectra of the leaching residues proved that no copper containing mineralogical phase was produced by the reactions between Cu2+ and marmatite. The X-ray photoelectron spectroscopy (XPS) analysis indicated that Cu2+ was first adsorbed on the marmatite surface and then produced Cu-S surface species. An electrochemical measurement further indicated that the adsorption of Cu2+ can remarkably enhance the electrochemical reactivity of the marmatite surface, thus catalyzing the oxidative dissolution process. However, a high percentage of Cu2+ adsorption on the marmatite surface can produce a passivation layer when the Cu2+ concentration is high in the solution, which decreases the electrochemical reactivity, thus resulting in the hinderance of the oxidative dissolution process of marmatite.

Mechanistic studies on reversible conversion reaction in Li2MnO3-carbon nanotube composite anode

Li2MnO3 is a popular cathode material in lithium-ion batteries, however in this study Li2MnO3-carbon nanotube composite is utilized as an anode material and its electrochemical reaction mechanism is systematically studied by using electrochemical, synchrotron radiation-based X-ray diffraction and absorption techniques along with the density functional calculations. This material demonstrates a significantly high initial reversible capacity of 1006.4 mAh g−1. Electrochemical characterization suggests that this unique anode material operates by a conversion reaction, involving the formation of Li2O and Mn metal. Diffraction patterns are measured at different state of charge and Pawley fitting of these patterns reveal that during lithiation Li2MnO3 initially converts into Mn3O4 and at the end of discharge, Li2O and Mn phases are formed. During delithiation, Li2MnO3 is not reversibly formed, instead [Li0.5Mn0.5]O-type phase appears after a complete electrochemical cycle. X-ray absorption spectroscopy and density functional calculations are used to confirm the validity of the electrochemical redox reaction mechanism derived from the electrochemical and diffraction measurements.

Magnetic-Sensitive Nanoparticle Self-Assembled Superhydrophobic Biopolymer-Coated Slow-Release Fertilizer: Fabrication, Enhanced Performance, and Mechanism.

Although commercialized slow-release fertilizers coated with petrochemical polymers have revolutionarily promoted agricultural production, more research should be devoted to developing superhydrophobic biopolymer coatings with superb slow-release ability from sustainable and ecofriendly biomaterials. To inform the development of the superhydrophobic biopolymer-coated slow-release fertilizers (SBSF), the slow-release mechanism of SBSF needs to be clarified. Here, the SBSF with superior slow-release performance, water tolerance, and good feasibility for large-scale production was self-assembly fabricated using a simple, solvent-free process. The superhydrophobic surfaces of SBSF with uniformly dispersed Fe3O4 superhydrophobic magnetic-sensitive nanoparticles (SMNs) were self-assembly constructed with the spontaneous migration of Fe3O4 SMNs toward the outermost surface of the liquid coating materials ( i.e., pig fat based polyol and polymethylene polyphenylene isocyanate in a mass ratio 1.2:1) in a magnetic field during the reaction-curing process. The results revealed that SBSF showed longer slow-release longevity (more than 100 days) than those of unmodified biopolymer-coated slow-release fertilizers and excellent durable properties under various external environment conditions. The governing slow-release mechanism of SBSF was clarified by directly observing the atmosphere cushion on the superhydrophobic biopolymer coating using the synchrotron radiation-based X-ray phase-contrast imaging technique. Liquid water only contacts the top of the bulges of the solid surface (10.9%), and air pockets are trapped underneath the liquid (89.1%). The atmosphere cushion allows the slow diffusion of water vapor into the internal urea core of SBSF, which can decrease the nutrient release and enhance the slow-release ability. This self-assembly synthesis of SBSF through the magnetic interaction provides a strategy to fabricate not only ecofriendly biobased slow-release fertilizers but also other superhydrophobic materials for various applications.

Sensitivity comparison of absorption and grating-based phase tomography of paraffin-embedded human brain tissue

Advances in high-resolution hard X-ray computed tomography have led to the field of virtual histology to complement histopathological analyses. Phase-contrast modalities have been favored because, for soft tissues, the real part of the refractive index is orders of magnitude greater than the imaginary part. Nevertheless, absorption-contrast measurements of paraffin-embedded tissues have provided exceptionally high contrast combined with a submicron resolution. In this work, we present a quantitative comparison of phase tomography using synchrotron radiation-based X-ray double grating interferometry and conventional synchrotron radiation-based computed tomography in the context of histopathologically relevant paraffin-embedded human brain tissue. We determine the complex refractive index and compare the contrast-to-noise ratio (CNR) of each modality, accounting for the spatial resolution and optimizing the photon energy for absorption tomography. We demonstrate that the CNR in the phase modality is 1.6 times higher than the photon-energy optimized and spatial resolution-matched absorption measurements. We predict, however, that a further optimized phase tomography will provide a CNR gain of 4. This study seeks to boost the discussion of the relative merits of phase and absorption modalities in the context of paraffin-embedded tissues for virtual histology, highlighting the importance of optimization procedures for the two complementary modes and the trade-off between spatial and density resolution, not to mention the disparity in data acquisition and processing.

Tracking Structural Self-Reconstruction and Identifying True Active Sites toward Cobalt Oxychloride Precatalyst of Oxygen Evolution Reaction.

Unravelling the intrinsic mechanism of electrocatalytic oxygen evolution reaction (OER) by use of heterogeneous catalysts is highly desirable to develop related energy conversion technologies. Albeit dynamic self-reconstruction of the catalysts during OER is extensively observed, it is still highly challenging to operando probe the reconstruction and precisely identify the true catalytically active components. Here, a new class of OER precatalyst, cobalt oxychloride (Co2 (OH)3 Cl) with unique features that allow a gradual phase reconstruction during OER due to the etching of lattice anion is demonstrated. The reconstruction continuously boosts OER activities. The reconstruction-derived component delivers remarkable performance in both alkaline and neutral electrolytes. Operando synchrotron radiation-based X-ray spectroscopic characterization together with density functional theory calculations discloses that the etching of lattice Cl- serves as the key to trigger the reconstruction and the boosted catalytic performance roots in the atomic-level coordinatively unsaturated sites (CUS). This work establishes fundamental understanding on the OER mechanism associated with self-reconstruction of heterogeneous catalysts.

Investigation of calcium and zinc distribution in rabbit patella-patellar tendon interface using synchrotron radiation micro X-ray fluorescence technique

Objective The unique distributions and maps of calcium and zinc at the regions of interest in patella-patellar tendon interface (PPTI) were detected by synchrotron radiation micro X-ray fluorescence (SR-μXRF). Methods Healthy New Zealand rabbits were used in this experiment. Five harvested PPTI samples were cut along the sagittal plane of the PPTI by a microtome. Sections of PPTI were then scanned by SR-μXRF at BL15U1 of shanghai synchrotron radiation facility (SSRF) in China. Then the samples were used for histological staining with hematoxylin and eosin (HE) and Van-Gieson. Results Histological staining showed that the thickness of calcified fibrocartilage in PPTI was (163.00±42.00) μm; The distributions and characterization of calcium and zinc of PPTI were successfully obtained via the SR-μXRF. The maximum calcium content [93 853 cps, (28.00±9.05) times of that of patellar tendon] was found in the transitional zone of calcified fibrocartilage region and the patella. A significant accumulation of zinc [10 100 cps, (3.20±0.65) times of that of patellar tendon] was exhibited in the transition area of tidemark. The maximum content of zinc was (8.70±3.20) times of that of calcium. The distribution distance between the maximum content of calcium and zinc was (135.00±16.00) μm, which was consistent with histological staining (r2=0.935). Conclusion SR-μXRF served as a high-precision and high-resolution instrument to qualitatively assess the distributions of calcium and zinc in the PPTI, which provides a new insight for the study of bone tendon interface repair. Key words: Synchrotron radiation-based micro X-ray fluorescence analysis; Calcium; Zinc; Bone tendon interface

Nature and spatial distribution of extended defects in Czochralski-grown Ca3RE2(BO3)4 (RE = Y, Gd) orthoborate single crystals

Pure and Nd-doped Ca3Y2(BO3)4 and Ca3Gd2(BO3)4 orthoborate (space group Pnma) single crystals are considered for applications as materials for optoelectronics, in particular for ultrafast pulse lasers. In the present work, Czochralski-grown single crystals of such materials were studied. All of them were nearly free of defects such as impurity phases or gas bubble inclusions, previously observed and reported in similar orthoborates. Laboratory high-resolution x-ray diffraction together with synchrotron radiation-based white-beam x-ray topography have been employed as experimental techniques. In this paper we perform for the first time a systematic study of extended defects present in those crystals, including the spatial distribution of the defects. The crystal quality of the studied Ca3RE2(BO3)4 samples is relatively good—the mean values of double-axis rocking-curve full width at half maximum are low enough low (in the order of 32–131 arcsec) and comparable with literature results obtained for other borate crystals. The chemical composition is generally uniform along the samples. The nature of the extended defects is recognized—they are mainly crystal blocks with low misorientation angles ⩽0.06°), micromosaics, dislocations, and crystallographic plane bending. A detailed analysis of the bend for each crystal is presented. Simple criteria for classifying bulk crystals in terms of bending profile are formulated.

Carbon Defect-Induced Reversible Carbon-Oxygen Interfaces for Efficient Oxygen Reduction.

It is a great challenge to fabricate a metal-free oxygen reduction reaction (ORR) electrocatalyst that can operate well in the acidic medium and fuel cells system. Here, a metal-free carbon material C-900 with abundant defect sites is fabricated by a self-sacrificed template and a solid-state reaction strategy. C-900 shows a superior performance to 20% Pt/C in alkaline medium and a performance closer to 20% Pt/C in acidic condition. It can thus be applied in air-breathing fuel cell (without extra operation pressure) as the cathode catalyst, which shows a high performance (1160 W L-1; ∼62% of 20% Pt/C) with excellent stability. By using oxygen temperature-programmed desorption, the strong selective chemisorption of O2 on C-900 has been revealed. The excellent chemisorption property of C-900 may originate from the large amounts of carbon defect sites, which have been confirmed by synchrotron radiation-based X-ray absorption spectroscopy. The rich defect sites and excellent chemisorption property can thus induce reversible carbon-oxygen interface for the excellent ORR activity.

Modification of poly(ethylene glycol) on the microstructure and mechanical properties of calcium silicate hydrates

With the aim of creating more sustainable building materials, calcium silicate hydrate (C-S-H), the primary binding phase in modern concrete, was integrated with poly(ethylene glycol) (PEG). At the crystal lattice scale, synchrotron radiation-based high-pressure X-ray diffraction (HP-XRD) reveals that the incorporation of PEG increases the ab-planar stiffness of C-S-H leading to a higher bulk modulus, while molecular simulation results indicate polymers are not likely intercalated into the interlayer region. At a higher length scale, nanoindentation measurements show the introduction of PEG lowers the packing density of C-S-H particles and, thus, decreases the indentation modulus. However, a high creep resistance of the C-S-H/PEG sample is still maintained, which suggests a meso-composite may form to restrict the rapid translation between neighboring calcium silicate sheets. Furthermore, 29Si nuclear magnetic resonance (NMR) shows that the presence of PEG shortens the mean chain length of C-S-H, making dimer the predominant structure.

Probe active sites of heterogeneous electrocatalysts by X-ray absorption spectroscopy: From single atom to complex multi-element composites

Abstract As the design of heterogeneous electrocatalysts is entering the ‘atom’ age, synchrotron radiation-based X-ray absorption spectroscopy (XAS) has started to expand its strategic presence in electrocatalysis. XAS has demonstrated its usefulness in determining the electronic and geometric structures of supported single atom catalysts thanks to its high sensitivities towards elemental, chemical, and orbital determination. Nowadays, it is expected that the role of XAS will further increase as current research interests are shifting to more complex size-selected single- or multi-element atomic clusters, including challenging electrochemical processes. This review discusses the latest applications of XAS in characterization of electrocatalysts with atomic dispersion, such as single atoms and clusters. Involved advanced analyses methods like wavelet transform, as well as outlooks and challenges for revealing the dynamic behaviours of catalytic active sites using in-situ XAS are also presented and discussed.

A balance of redox and ligand-exchange processes in the reaction of H2[OsCl6] with thiourea: Isolation and characterization of a novel osmium complex [(NH2)2CSSC(NH2)2]2[OsIVCl6]Cl2·3H2O

A novel complex with the stoichiometry [(NH2)2CSSC(NH2)2]2[OsIVCl6]Cl2·3H2O (1) is isolated as a product of the reaction of H2[OsCl6] with thiourea in concentrated HCl under deliberately optimized conditions favoring a partial thiourea oxidation to α,α′-dithiobisformamidinium dication but preserving hexachloroosmate [OsCl6]2- anions. A bromide analogue [(NH2)2CSSC(NH2)2]2[OsIVBr6]Br2·3H2O 2 is afforded by a similar reaction. A counter synthesis of 1 is accomplished via the direct ion-exchange reaction between H2[OsCl6] and [S2C2(NH2)4]Cl2. Crystal structures of 1 and 2 are unambiguously established by synchrotron radiation-based single-crystal X-ray diffraction at 100 K. The two compounds are isostructural and are crystallized in the orthorhombic space group Cmcm, Z = 4. Unit cell parameters are for 1:a = 11.279(2) Å, b = 13.611(3) Å, c = 16.731(3) Å; for 2: a = 11.695(2) Å, b = 14.005(3) Å, c = 17.015(3) Å. The osmium atoms in [OsX6]2− (X = Cl or Br) anions adopt slightly distorted octahedral coordination. The α,α′-dithiobisformamidinium cations are paired into rings via the NH…Cl− hydrogen bonds. The rings are further linked into a spatial network by H-bonds with water molecules and S…Cl nonvalence interactions.

Synchrotron Radiation Based Study of the Catalytic Mechanism of Ag+ to Chalcopyrite Bioleaching by Mesophilic and Thermophilic Cultures

The catalytic mechanism of Ag+ for chalcopyrite bioleaching by mesophilic culture (at 30 °C) and thermophilic culture (at 48 °C) was investigated using synchrotron radiation-based X-ray diffraction (SR-XRD) and S K-edge and Fe L-edge X-ray absorption near edge structure (XANES) spectroscopy. Bioleaching experiments showed that copper extraction from chalcopyrite bioleaching by both cultures was promoted significantly by Ag+, with more serious corrosion occurring on the minerals surface. SR-XRD and XANES analyses showed that the intermediates S0, jarosite and secondary minerals (bornite, chalcocite and covellite) formed for all bioleaching experiments. For these secondary minerals, the formation of bornite and covellite was promoted significantly in the presence of Ag+ for both cultures, while Ag+ has almost no effect on the formation of chalcocite. These results provided insight into the catalytic mechanisms of Ag+ to chalcopyrite bioleaching by the mesophilic and thermophilic cultures, which are both probably due to the rapid formation of bornite by Ag+ and the conversion of bornite to covellite.

Role of the Relative Humidity and the Cd/Zn Stoichiometry in the Photooxidation Process of Cadmium Yellows (CdS/Cd1-x Znx S) in Oil Paintings.

Cadmium yellows (CdYs) refer to a family of cadmium sulfide pigments, which have been widely used by artists since the late 19th century. Despite being considered stable, they are suffering from discoloration in iconic paintings, such as Joy of Life by Matisse, Flowers in a blue vase by Van Gogh, and The Scream by Munch, most likely due to the formation of CdSO4 ⋅n H2 O. The driving factors of the CdYs degradation and how these affect the overall process are still unknown. Here, we study a series of oil mock-up paints made of CdYs of different stoichiometry (CdS/Cd0.76 Zn0.24 S) and crystalline structure (hexagonal/cubic) before and after aging at variable relative humidity under exposure to light and in darkness. Synchrotron radiation-based X-ray methods combined with UV-Vis and FTIR spectroscopy show that: 1) Cd0.76 Zn0.24 S is more susceptible to photooxidation than CdS; both compounds can act as photocatalysts for the oil oxidation. 2) The photooxidation of CdS/Cd0.76 Zn0.24 S to CdSO4 ⋅n H2 O is triggered by moisture. 3) The nature of alteration products depends on the aging conditions and the Cd/Zn stoichiometry. Based on our findings, we propose a scheme for the mechanism of the photocorrosion process and the photocatalytic activity of CdY pigments in the oil binder. Overall, our results form a reliable basis for understanding the degradation of CdS-based paints in artworks and contribute towards developing better ways of preserving them for future generations.

Osteo-regeneration personalized for children by rapid maxillary expansion: an imaging study based on synchrotron radiation microtomography

BackgroundPersonalized maxillary expansion procedure has been proposed to correct maxillary transversal deficiency; different protocols of stem cell activation have been suggested and rapid maxillary expansion (RME) is the most commonly used among clinicians. The present study aimed to quantify in three-dimensions (3D) the osteo-regeneration of the midpalatal suture in children submitted to RME.MethodsThree patients (mean age 8.3 ± 0.9 years) were enrolled in the study to preform biopsy of midpalatal suture. Two patients (subjects 1 and 2) were subjected to RME before biopsy. The third patient did not need maxillary expansion treatment and was enrolled as control (subject 3). Midpalatal suture samples were harvested 7 days after RME in subject 1, and 30 days after RME in subject 2. The samples were harvested with the clinical aim to remove bone for the supernumerary tooth extraction. When possible, maxillary suture and bone margins were both included in the sample. All the biopsies were evaluated by complementary imaging techniques, namely Synchrotron Radiation-based X-ray microtomography (microCT) and comparative light and electron microscopy.ResultsIn agreement with microscopy, it was detected by microCT a relevant amount of newly formed bone both 7 days and 30 days after RME, with bone growth and a progressive mineralization, even if still immature respect to the control, also 30 days after RME. Interestingly, the microCT showed that the new bone was strongly connected and cross-linked, without a preferential orientation perpendicular to the suture’s long axis (previously hypothesized by histology), but with well-organized and rather isotropic 3D trabeculae.ConclusionsThe microCT imaging revealed, for the first time to the authors’ knowledge, the 3D bone regeneration in children submitted to RME.

Quantitative Scanning Laue Diffraction Microscopy: Application to the Study of 3D Printed Nickel-Based Superalloys

Progress in computing speed and algorithm efficiency together with advances in area detector and X-ray optics technologies have transformed the technique of synchrotron radiation-based scanning Laue X-ray microdiffraction. It has now evolved into a near real-time quantitative imaging tool for material structure and deformation at the micrometer and nanometer scales. We will review the achievements of this technique at the Advanced Light Source (Berkeley, CA, USA), and demonstrate its application in the thorough microstructural investigations of laser-assisted 3D printed nickel-based superalloys.

Nano-imaging of environmental dust in human lung tissue by soft and hard X-ray fluorescence microscopy

It is well recognized that a large number of pulmonary diseases are induced by the effects of inhaled particulates. Anthracosis is defined as an asymptomatic, mild form of pneumoconiosis caused by the accumulation of “black carbon” in the lungs due to repeated exposure to air pollution or inhalation of smoke or coal dust particles. Since the human population is progressively exposed to an increasing number and doses of anthropogenic micro and nano particles/compounds, there is a pressing urgency to explore toxicological impact arising from these exposures and the molecular mechanisms driving the body defense or possible related diseases. The toxicity mechanisms are clearly related to chemical composition and physical and surface properties of materials. A combination of synchrotron radiation-based (SR-based) nano X-ray fluorescence (XRF) imaging and soft X-ray microscopy was used to chemically characterize environmental particulates (anthracosis) in lung tissues from urban subjects with the aim of better understanding the complex nature of related lungs' deposits. High-resolution XRF analyses performed at ESRF and Elettra synchrotrons allowed discriminating single particles in the heterogeneous aggregates found in the lung tissue. The small particles have variable composition resulting from the different combinations of Ti with O, K and Si, Al and Si, or Zn and Fe with O. Interestingly, simultaneous absorption and phase contrast images showed the particulate morphology and allowed to predict the presence of very dense nanoparticles or high concentration of heavy elements.

Operando Evidence for a Universal Oxygen Evolution Mechanism on Thermal and Electrochemical Iridium Oxides.

Progress in the development of proton exchange membrane (PEM) water electrolysis technology requires decreasing the anode overpotential, where the sluggish multistep oxygen evolution reaction (OER) occurs. This calls for an understanding of the nature of the active OER sites and reaction intermediates, which are still being debated. In this work, we apply synchrotron radiation-based near-ambient pressure X-ray photoelectron and absorption spectroscopies under operando conditions in order to unveil the nature of the reaction intermediates and shed light on the OER mechanism on electrocatalysts most widely used in PEM electrolyzers-electrochemical and thermal iridium oxides. Analysis of the O K-edge and Ir 4f spectra backed by density functional calculations reveals a universal oxygen anion red-ox mechanism regardless of the nature (electrochemical or thermal) of the iridium oxide. The formation of molecular oxygen is considered to occur through a chemical step from the electrophilic OI- species, which itself is formed in an electrochemical step.