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International audience; INTRODUCTION: Organic compounds in asteroids and comets contain information about the early history of the Solar System. They could also have delivered organic material to early Earth. The Hayabusa2 spacecraft visited the carbonaceous asteroid Ryugu and collected samples of its surface materials, which were brought to Earth in December 2020. RATIONALE: We investigated the macromolecular organic matter in the Ryugu samples, measuring its elemental, isotopic, and functional group compositions along with its small-scale structures and morphologies. Analytical methods used included spectro-microscopies, electron microscopy, and isotopic microscopy. We examined intact Ryugu grains and insoluble carbonaceous residues isolated by acid treatment of the Ryugu samples. RESULTS: Organic matter is abundant in the Ryugu grains, distributed as submicrometersized organic grains and as organic matter dispersed in matrix. The Ryugu organic matter consists of aromatic carbons, aliphatic carbons, ketones, and carboxyls. The functional group

Ptychographic coherent diffraction imaging (CDI) allows the visualization of both the structure and chemical state of materials on the nanoscale, and has been developed for use in the soft and hard X-ray regions. In this study, a ptychographic CDI system with pinhole or Fresnel zone-plate optics for use in the tender X-ray region (2–5 keV) was developed on beamline BL27SU at SPring-8, in which high-precision pinholes optimized for the tender energy range were used to obtain diffraction intensity patterns with a low background, and a temperature stabilization system was developed to reduce the drift of the sample position. A ptychography measurement of a 200 nm thick tantalum test chart was performed at an incident X-ray energy of 2.500 keV, and the phase image of the test chart was successfully reconstructed with approximately 50 nm resolution. As an application to practical materials, a sulfur polymer material was measured in the range of 2.465 to 2.500 keV including the sulfur K absorption edge, and the phase and absorption images were successfully reconstructed and the nanoscale absorption/phase spectra were derived from images at multiple energies. In 3 GeV synchrotron radiation facilities with a low-emittance storage ring, the use of the present system will allow the visualization on the nanoscale of the chemical states of various light elements that play important roles in materials science, biology and environmental science.

Context. The current period is conducive to exploring our Solar System's origins with recent and future space sample return missions, which provide invaluable information from known Solar System asteroids and comets The Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) recently brought back samples from the surface of the Ryugu carbonaceous asteroid. Aims. We aim to identify the different forms of chemical composition of organic matter and minerals that constitute these Solar System primitive objects, to shed light on the Solar System's origins. Methods. In this work, we recorded infrared (IR) hyper-spectral maps of whole-rock Ryugu asteroid samples at the highest achievable spatial resolution with a synchrotron in the mid-IR (MIR). Additional global far-IR (FIR) spectra of each sample were also acquired. Results. The hyper-spectral maps reveal the variability of the functional groups at small scales and the intimate association of phyl-losilicates with the aliphatic components of the organic matter present in Ryugu. The relative proportion of column densities of the identified IR functional groups (aliphatics, hydroxyl + interlayer and/or physisorbed water, carbonyl, carbonates, and silicates) giving access to the composition of the Ryugu samples is estimated from these IR hyper-spectral maps. Phyllosilicate spectra reveal the presence of mixtures of serpentine and saponite. We do not detect anhydrous silicates in the samples analysed, at the scales probed. The carbonates are dominated by dolomite. Aliphatics organics are distributed over the whole samples at the micron scale probed with the synchrotron, and intimately mixed with the phyllosilicates. The aromatic C=C contribution could not be safely deconvolved from OH in most spectra, due to the ubiquitous presence of hydrated minerals. The peak intensity ratios of the organics methylene to methyl (CH2/CH3) of the Ryugu samples vary between about 1.5 and 2.5, and are compared to the ratios in chondrites from types 1 to 3. Overall, the mineralogical and organic characteristics of the Ryugu samples show similarities with those of CI chondrites, although with a noticeably higher CH2/CH3 in Ryugu than generally measured in C1 chondrites collected on Earth, and possibly a higher carbonate content.

Anion doping is considered a promising approach to improve battery performance by utilizing the functionalities of anion defects. Although the oxygen vacancy is the simplest anion defect in oxide-based cathode materials, the relationship among the oxygen vacancy, crystal structure, electronic structure and electrochemical properties has been poorly understood so far. Here, we controlled the oxygen vacancy concentration in Li1.2Ni0.13Co0.13Mn0.54O2−δ quantitatively by using a solid-electrolyte cell composed of an oxide-ion conductor and evaluated the impact of oxygen vacancies on the electrochemical properties of Li1.2Ni0.13Co0.13Mn0.54O2−δ. It was revealed that the introduction of oxygen vacancies caused reduction expansion of the crystal lattice and selective reduction of Ni and Co. Oxygen-deficient Li1.2Ni0.13Co0.13Mn0.54O1.94 showed better energy density retention (90% after 90 cycles) than the oxygen-stoichiometric sample (72%) by mitigating the voltage decay and the capacity fading upon cycling. We proposed that the enhancement of the reversible transition metal migration due to the reduction expansion of the crystal lattice mitigated the voltage decay, and selective reduction of Ni and Co enhanced the redox capability of Ni and Co in the subsequent charge/discharge. The findings of this work proved the effectiveness of oxygen defect engineering for oxide-based battery materials.

Wurtzite AlN films with high Fe concentrations were deposited on Si(100) substrates using radio-frequency sputtering, and the growth process was investigated. X-Ray diffraction (XRD) analysis with parallel incident X-rays showed that a thick film (∼2.5 μm) had a non-polar a-axis orientation, similar to the films deposited on SiO2 glass substrates. Through powder XRD analysis, it was found that non-wurtzite fine crystals and/or amorphous materials formed during the initial stage of deposition, followed by wurtzite nucleation with various orientations of the axes, such as a, m, and r orientations. The XRD results also implied that the a-axis-oriented regions drastically increased with increasing film thickness. Scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy analyses suggested that one of the candidates for the non-wurtzite fine crystalline material was γ-Al2O3. STEM analysis also demonstrated that a-axis-oriented single-crystal grains grew from randomly oriented small wurtzite grains that increased in diameter with increasing deposition time. Al K-edge X-ray absorption near-edge structure results suggested that the electronic structure in the polar c-axis direction of wurtzite lying in the film plane developed with deposition time, thereby further supporting the findings of the XRD and STEM analyses.

To clarify the effects of anion species and solvents on the Coulombic efficiency and polarization of magnesium deposition/dissolution reactions, the anode/electrolyte interfacial behavior of magnes...

Atmospheric deposition is one of the main sources of dissolved iron (Fe) in the ocean surfaces. Atmospheric processes are recognized as controlling fractional Fe solubility (Fesol%) in marine aerosol particles. However, the impact of these processes on Fesol% remains unclear. One of the reasons for this is the lack of field observations focusing on the relationship between Fesol% and Fe species in marine aerosol particles. In particular, the effects of organic ligands on Fesol% have not been thoroughly investigated in observational studies. In this study, Fe species in size-fractionated aerosol particles in the Pacific Ocean were determined using X-ray absorption fine structure (XAFS) spectroscopy. The internal mixing states of Fe and organic carbon were investigated using scanning transmission X-ray microscopy (STXM). The effects of atmospheric processes on Fesol% in marine aerosol particles were investigated based on the speciation results. Iron in size-fractionated aerosol particles was mainly derived from mineral dust, regardless of aerosol diameter, because the enrichment factor of Fe was almost 1 in both coarse (PM>1.3) and fine aerosol particles (PM1.3). Approximately 80 % of the total Fe (insoluble + labile Fe) was present in PM>1.3, whereas labile Fe was mainly present in PM1.3. The Fesol% in PM>1.3 was not significantly increased (2.56±2.53 %, 0.00 %–8.50 %, n=20) by the atmospheric processes because mineral dust was not acidified beyond the buffer capacity of calcite. In contrast, mineral dust in PM1.3 was acidified beyond the buffer capacity of calcite. As a result, Fesol% in PM1.3 (0.202 %–64.7 %, n=10) was an order of magnitude higher than that in PM>1.3. The PM1.3 contained ferric organic complexes with humic-like substances (Fe(III)-HULIS, but not Fe-oxalate complexes), and the abundance correlated with Fesol%. Iron(III)-HULIS was formed during transport in the Pacific Ocean because Fe(III)-HULIS was not found in aerosol particles in Beijing and Japan. The pH estimations of mineral dust in PM1.3 established that Fe was solubilized by proton-promoted dissolution under highly acidic conditions (pH < 3.0), whereas Fe(III)-HULIS was stabilized under moderately acidic conditions (pH 3.0–6.0). Since the observed labile Fe concentration could not be reproduced by proton-promoted dissolution under moderately acidic conditions, the pH of mineral dust increased after proton-promoted dissolution. The cloud process in the marine atmosphere increases the mineral dust pH because the dust particles are covered with organic carbon and Na. The precipitation of ferrihydrite was suppressed by Fe(III)-HULIS owing to its high water solubility. Thus, the organic complexation of Fe with HULIS plays a significant role in the stabilization of Fe that was initially solubilized by proton-promoted dissolution.

Oxygen defects are closely related to the battery performance of oxide-based cathode active materials for lithium-ion batteries, and especially, positive influences have been reported in Li-rich ca...

The charge/discharge capacity of current lithium-ion battery cathode materials is limited by the charge compensation of transition-metal redox during the charge/discharge processes. Recently, the u...

Oxygen release from oxide-based cathode materials is a key phenomenon for the realization of high performance and highly reliable next-generation batteries, because it can be a trigger for a thermal runaway and closely related to electrochemical performances. In this study, the mechanism of oxygen release from Li1.2Mn0.6Ni0.2O2−δ and the corresponding electronic and crystal structural changes were studied. Li1.2Mn0.6Ni0.2O2−δ showed oxygen deficient nonstoichiometry until δ ≈ 0.042, and further oxygen extraction resulted in the reductive decomposition to MnNi6O8 and Li–Mn enriched Li(Li,Mn,Ni)O2−δ′. The oxygen vacancy formation mechanism was investigated by the defect chemical and thermodynamic analyses, and the oxygen vacancy formation energy was calculated from the nonstoichiometric data (ca. 2.03 eV). It was clearly confirmed that the lattice parameters and the distances of Mn–O and Ni–O were increased by the oxygen vacancy formation, which is known as the reduction expansion in nonstoichiometric compounds. Cooperative reduction of Ni, Mn and O due to the oxygen vacancy formation was observed from Ni-L, Mn-L and O-K edge X-ray absorption spectra. The charge compensation of the oxygen vacancy formation was maintained mainly by the reduction of Ni3+ to Ni2+ and mildly by the reduction of Mn4+ and O2−.

Absolute measurements of small-angle X-ray scattering (SAXS) intensities at the K absorption edge of Mg have been performed using glassy carbon as an intensity standard. Glassy carbon samples polished down to give appropriate transmission have been prepared as a secondary standard to be used at 1.3 keV. Al–Mg binary alloys were used to assess the metastable phase boundary for the Al3Mg metastable precipitation from the absolute scattering intensity. The assessed phase boundary agreed with the previous reports. Glassy carbon was concluded to be an appropriate candidate for an intensity standard sample for transmission measurements of SAXS in the tender X-ray regions.

A nanoparticle (NP)-based precatalyst has been developed for organic synthesis: sulfur-modified Au-supported Fe (SAFe). The SAFe was easily prepared through a three-step procedure involving simultaneous in situ metal NP and nanospace organization (PSSO). This method avoids the need for preformed templates for immobilizing and stabilizing the metal nanoparticles. On account of the relative safety and enormous earth abundance of iron, SAFe potentially represents an ideal precatalyst for carbon–carbon bond-forming cross-coupling reactions. As such, it has been applied as a precatalyst to Kumada coupling under ligand-free conditions, proving to be capable of being recycled and used repeatedly for this reaction. Analysis of SAFe and of reaction mixtures suggested that the active species in these reactions are produced in situ by assemblies of iron-based NPs.

Self-assembled multilayer iron(0) nanoparticles (NPs, 6-10 nm), namely, sulfur-modified Au-supported Fe(0) [SAFe(0)], were developed for ligand-free one-pot carbon-carbon/carbon-nitrogen bond-forming reactions. SAFe(0) was successfully prepared using a well-established metal-nanoparticle catalyst preparative protocol by simultaneous in situ metal NP and nanospace organization (PSSO) with 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine (Si-DHP) as a strong reducing agent. SAFe(0) was easy to handle in air and could be recycled with a low iron-leaching rate in reaction cycles.

To clarify the origin of the polarization of magnesium deposition/dissolution reactions, we combined electrochemical measurement, operando soft X-ray absorption spectroscopy (operando SXAS), Raman, and density functional theory (DFT) techniques to three different electrolytes: magnesium bis(trifluoromethanesulfonyl)amide (Mg(TFSA)2)/triglyme, magnesium borohydride (Mg(BH4)2)/tetrahydrofuran (THF), and Mg(TFSA)2/2-methyltetrahydrofuran (2-MeTHF). Cyclic voltammetry revealed that magnesium deposition/dissolution reactions occur in Mg(TFSA)2/triglyme and Mg(BH4)2/THF, while the reactions do not occur in Mg(TFSA)2/2-MeTHF. Raman spectroscopy shows that the [TFSA]- in the Mg(TFSA)2/triglyme electrolyte largely does not coordinate to the magnesium ions, while all of the [TFSA]- in Mg(TFSA)2/2-MeTHF and [BH4]- in Mg(BH4)2/THF coordinate to the magnesium ions. In operando SXAS measurements, the intermediate, such as the Mg+ ion, was not observed at potentials above the magnesium deposition potential, and the local structure distortion around the magnesium ions increases in all of the electrolytes at the magnesium electrode|electrolyte interface during the cathodic polarization. Our DFT calculation and X-ray photoelectron spectroscopy results indicate that the [TFSA]-, strongly bound to the magnesium ion in the Mg(TFSA)2/2-MeTHF electrolyte, undergoes reduction decomposition easily, instead of deposition of magnesium metal, which makes the electrolyte inactive electrochemically. In the Mg(BH4)2/THF electrolyte, because the [BH4]- coordinated to the magnesium ions is stable even under the potential of the magnesium deposition, the magnesium deposition is not inhibited by the decomposition of [BH4]-. Conversely, because [TFSA]- is weakly bound to the magnesium ion in Mg(TFSA)2/triglyme, the reduction decomposition occurs relatively slowly, which allows the magnesium deposition in the electrolyte.

Understanding the origin of organic material on Mars is a major issue in modern planetary science. Recent robotic exploration of Martian sedimentary rocks and laboratory analyses of Martian meteorites have both reported plausible indigenous organic components. However, little is known about their origin, evolution, and preservation. Here we report that 4-billion-year-old (Ga) carbonates in Martian meteorite, Allan Hills 84001, preserve indigenous nitrogen(N)-bearing organics by developing a new technique for high-spatial resolution in situ N-chemical speciation. The organic materials were synthesized locally and/or delivered meteoritically on Mars during Noachian age. The carbonates, alteration minerals from the Martian near-surface aqueous fluid, trapped and kept the organic materials intact over long geological times. This presence of N-bearing compounds requires abiotic or possibly biotic N-fixation and ammonia storage, suggesting that early Mars had a less oxidizing environment than today., Mars has long been thought to contain organic compounds, but the origins and plausibility are debated. Here the authors employ a new technique to assess organic nitrogen compounds in a Martian meteorite, concluding that these compounds are indeed likely to originate from the Red Planet.

Mechanism of magnesium ion alloying reaction into bismuth electrode in magnesium bis(trifluoromethanesulfonyl)amide (Mg(TFSA)2)/acetonitrile (AN) and Mg(TFSA)2/2-methyltetrahydrofuran (2-MeTHF) ele...

To reliably utilize the information on growth and environment stored within the hard carbonate shells of long-lived bivalves, it is necessary to accurately count the annual growth lines from their shell cross-sections. In this study, we investigated the relationship between the distribution of minor elements and visual lines in the shell cross-sections of the long-lived mussel Margaritifera laevis collected from the Chitose River in Hokkaido, Japan. The distribution of minor elements, such as sulfur (S), phosphorus (P), strontium (Sr), magnesium (Mg), and sodium (Na), in a cross-section of the umbo was determined by X-ray fluorescence analysis using synchrotron soft X-ray radiation. The chemical properties of S and P were analyzed in-situ using soft X-ray photoabsorption spectroscopy, and the chemical form dependence of S distribution was determined by speciation mapping. In addition, the annual and disturbance lines were visualized by staining shell cross-sections. Our results showed that the distribution of reduced S (i.e., S C and S H) corresponded to the annual lines, whereas the distribution of oxidized S (i.e., SO42−) corresponded to the disturbance lines. Overall, this study revealed that speciation analysis of S in shell cross-sections can be used to determine the origin of visual lines in chronological studies.

At a metal–ferroelectric junction, it has been considered that the electric polarization of the ferroelectric material can affect the electronic structure of the neighboring metal. Here, we demonstrate that the valence state of Pd can be shifted to the unstable high value of 4+ by the electric field of electric polarization in ferroelectric BaTiO3. Study of the absorption fine structure of both hard and soft x rays revealed the existence of Pd4+ states on the surface of Pd oxide nanoparticles. The positions of Pd and oxygen atoms are shifted in opposite directions by the electric field due to the electric polarization of ferroelectric BaTiO3. The atomic displacement of Pd and O forms a zigzag structure, in which the coordination number of Pd atoms is changed from four to six, producing a quadrivalent state. This report presents experimental evidence that ferroelectric polarization can control the electronic states of neighboring metal atoms, and we suggest that using the ferroelectric support effect may produce a new type of catalyst.

Using N K-edge XANES studies, we demonstrate a noticeable difference in local structure around the nitrogen atoms in as-deposited amorphous and annealed N-doped GeTe-based phase change alloys. The pronounced changes appear as a ≈ 2 eV shift in the absorption edge to higher photon energies and the overall shape of the XANES spectrum. Comparison of the experimental XANES spectrum of the as-deposited amorphous phase with ab-initio XANES simulations discloses that the as-deposited phase mainly consists of the NGe3 and the NTe3 pyramidal units in approximately equal concentration. When annealed, NTe3 units gradually rebond to the NGe3 units and at the same time N atoms diffuse through the amorphous phase to form the GexNy aggregates. Upon long-standing annealing at 400 ∘ C a compact interlayer of Ge3N4 is formed in the crystalline phase.

Sodium concentrations in biogenic CaCO3 are several thousands of parts per million, and, on a molar basis, Na is among the most abundant constituent minor element in these carbonates. Nevertheless, the chemical form of Na in CaCO3 is not well constrained. We used synchrotron X-ray spectroscopy to identify the dominant molecular host sites for Na in biogenic calcite and aragonite precipitated by corals, bivalves, and foraminifera. We also used the K-edge X-ray absorption near-edge structure to investigate the chemical environment of Na in biogenic calcium carbonates and identify the altervalent substitution of Na into Ca sites in the lattice structures of calcite and aragonite. Minor cation and anion concentrations in biogenic CaCO3 suggest that the principal substitution mechanism involves charge compensation through the creation of CO32− vacancies. The mostly homogeneous Na concentrations in the skeletal microstructures of the various biota we examined indicate that environmental and biological controls, such as temperature, skeletal microstructure, and calcification rates, have only minor influences on skeletal Na concentrations. A decrease of Na:Ca ratios with increasing age of foraminiferal shells picked from a Quaternary sediment core, indicates progressive release of Na, which suggests that structurally-substituted Na in biogenic CaCO3 is readily leached during burial diagenesis. Whereas the sediment that undergo diagenesis release some Na back to the water column, sodium co-precipitation in biogenic CaCO3 serves as a potential sink of Na for the ocean.

We report observations of the interatomic Coulombic decay (ICD) and electron-transfer-mediated decay (ETMD) from the triply charged states in Ne2 and NeAr dimers. The ICD processes leading to fragmentation of Ne3+-Ne into Ne3+-Ne+ and Ne3+-Ar into Ne3+-Ar+, and ETMD processes leading to fragmentation of Ne3+-Ne into Ne2+-Ne2+ are unambiguously identified by electron–ion-ion coincidence spectroscopy in which the kinetic energy of the ICD or ETMD electron and the kinetic energy release between the two fragment ions are measured in coincidence.

We developed a conceptually and methodologically novel ruthenium(0) nanoparticle catalyst, sulfur-modified Au-supported ruthenium nanoparticles (SARu). SARu is easily prepared through a three-step procedure involving simultaneous in situ metal nanoparticle and nanospace organization. This unique method does not require any conventional preformed template to immobilize and stabilize metal nanoparticles. SARu is an ideal ruthenium catalyst for liquid-phase combinatorial synthesis because it repeatedly catalyzes ligand-free Suzuki–Miyaura coupling of aryl halides, including aryl chlorides, with arylboronic acids with low Ru leaching. Physical analysis of SARu showed that the active species in these reactions were ruthenium (0) nanoparticles with a size of 1–3 nm. Also, we developed a continuously irradiating microwave methodology, which can first time discriminate the heating effect and the microwave effect in microwave experiments.

Oxygen isotope ratios (δ18O) and Mg/Ca ratios in organically produced calcium carbonate (calcite and aragonite) by marine species have been used as proxies for paleotemperature. The relationship between the components of large benthic foraminiferal tests (high-magnesium calcite) and seawater temperature has been little investigated yet. We conducted culture experiments using two species of reef-dwelling large benthic foraminifera under six temperature conditions (21–30°C). We selected the perforate species Calcarina gaudichaudii, and the imperforate species Amphisorus kudakajimensis, both of which are host to algal symbionts, for the experiments. The results indicated the significant correlation of Mg/Ca ratios (C. gaudichaudii and A. kudakajimensis) and δ18O (C. gaudichaudii) with temperature. The test weight of both species showed temperature dependency, with maxima at 27°C or 29°C and subsequent decline at 30°C. After correction for the contribution of the initial tests, which can be calculated from the weight ratios of the initial and cultured tests, the relationships of the Mg/Ca ratios and δ18O to temperature were obtained with the least squares best fit method as follows: C. gaudichaudii: T = 18.5–4.52 (δ18Oc–δ18Osw), A. kudakajimensis: T = 25.0–4.96 (δ18Oc–δ18Osw), and C. gaudichaudii and A. kudakajimensis: Mg/Ca = 2.85 T + 81.20. We concluded that species-specific calibration is unnecessary for Mg/Ca-temperature relationship, although it is necessary for δ18O related to the different calcification mechanisms of imperforate (A. kudakajimensis) and perforate (C. gaudichaudii) species.

We have studied the structure of styrene-butadiene rubber with anomalous small-angle X-ray scattering (ASAXS) at sulfur K -edge. The use of ASAXS at sulfur K -edge selectively changes the scattering contrast relating to sulfur, thereby leading to the structural study of low-contrast samples that would otherwise be difficult to be conducted. The energy range around the K -edge of sulfur has not been applied to scattering study, owing to mainly the absence of beamline and detector appropriate for the energy range. We have developed ASAXS setting with a transmission geometry at BL27SU, SPring-8 and have successfully obtained the scattering information relating to inhomogeneous distribution of sulfur in styrene-butadiene rubber. A two-phase model is applied for elucidating a coarse-grained view of the inhomogeneous structure. The results indicate that inhomogeneous distribution of polymer and sulfur is closely related and the dense part of polymer corresponds to the part being sparse of sulfur. This study opens up the possibility to elucidate a complex structure of macromolecular systems with a low scattering contrast.

The evaporites of the Realmonte salt mine (Sicily, Italy) are important archives recording the most extreme conditions of the Messinian Salinity Crisis (MSC). However, geochemical approach on these evaporitic sequences is scarce and little is known on the response of the biological community to drastically elevating salinity. In the present work, we investigated the depositional environments and the biological community of the shale¿anhydrite¿halite triplets and the K¿Mg salt layer deposited during the peak of the MSC. Both hopanes and steranes are detected in the shale¿anhydrite¿halite triplets, suggesting the presence of eukaryotes and bacteria throughout their deposition. The K¿Mg salt layer is composed of primary halites, diagenetic leonite, and primary and/or secondary kainite, which are interpreted to have precipitated from density-stratified water column with the halite-precipitating brine at the surface and the brine-precipitating K¿Mg salts at the bottom. The presence of hopanes and a trace amount of steranes implicates that eukaryotes and bacteria were able to survive in the surface halite-precipitating brine even during the most extreme condition of the MSC. Graphical abstract: [Figure not available: see fulltext.]. © 2019, The Author(s)., This work was performed with the support of Japan Society for the Promotion of Science (JSPS) Research Fellowship (16 J07844) to YI and JAMSTEC President Fund to NO.

The molecular-frame photoelectron angular distributions (MFPADs) in O 1s photoemission from CO2 molecule were measured. Patterns due to photoelectron diffractions were observed in the MFPADs. The polarization-averaged MFPADs were compared with theoretical calculation and were found to be useful in determining the molecular bond-length, which is a component to determine molecular structures.

Because reef-dwelling large benthic foraminifera (LBF) tests, which is composed of high-magnesium calcite, are the common components of modern reef sediments, and ancient reef carbonate rocks, they can provide a continuous record of the paleoenvironment of reef sediments. Evaluation of the responses of the minor element concentrations (Mg, Sr, Na, P, and S) of individual tests to ambient temperature and LBF growth modes was conducted with two cultured species, Calcarina gaudichaudii and Amphisorus kudakajimensis. The elements were assessed as tracers of temperature, salinity, nutrient concentration, and calcification rate. The Mg content of C. gaudichaudii and the Sr content of both species were controlled by temperature. It can be confirmed that the Mg of individual tests of C. gaudichaudii is a useful paleothermometer. There was a large biological modulation of Na, P, and S incorporation. In-situ XANES analysis revealed that both inorganic and organic species contributed to the P and S content of LBF tests. We observed five sulfur components with variable oxidation states.

Objectives Phosphoryl oligosaccharides of calcium (POs-Ca) are a highly soluble calcium source and can keep the solubility of calcium and fluoride ions. The aim of this study was to investigate the effect of calcium (from POs-Ca) and fluoride ions penetrate into subsurface enamel lesions in vitro . Design Demineralized bovine enamel slabs were remineralized in vitro for 24 hours at 37 °C with artificial saliva (AS) containing POs-Ca and various fluoride concentrations (0-100 ppm), or AS containing different levels of POs-Ca adjusted to a Ca/P ratio of 0.4-3.0 and fluoride, then were analyzed using Transversal microradiography. From those results, remineralization effects with optimal conditions were compared between POs-Ca and calcium chloride (CaCl 2 ). To determine the form of incorporated fluoride, we analyzed the chemical state and local structure of fluorine atoms integrated into enamel subsurface lesions using micro X-ray absorption near-edge structure (μ-XANES) spectroscopy. Results A significant mineral recovery rate was observed with POs-Ca and fluoride at 0.5 or 1.0 ppm (n = 6, p 2 (15.0 ± 9.6 %) (n = 5, mean ± SD, p Conclusions POs-Ca with fluoride-derived diffusion into subsurface enamel lesions facilitated formation of fluorapatite phases.

To understand the formation mechanism of carbon clusters in low-carbon steel, the dynamic behavior of carbon in solid solutions subjected to aging at low temperatures was investigated by X-ray absorption spectroscopy. While it is hypothesized that the C-Fe bond distance and lattice strain induced by the carbon in solid solution affect the formation and strengthening mechanism of carbon clusters in low-carbon steels, currently, there is no information on the local structure of carbon in ferritic steels. Therefore, in this study, the relationship between the correlation coefficient derived from C K near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and mechanical properties, in terms of Vickers hardness, was elucidated. The changes occurring in the spectral shape in the initial stages of aging were found to be clearly associated with the diffusion of carbon in the solid solution. The presence of the carbon-cluster precursor state suggested that the correlation coefficient calculated from the C K NEXAFS spectra experienced variations in spite of a constant Vickers hardness. Furthermore, we proposed a method to analyze the local structure of carbon in solid solution in steels using C K NEXAFS. Finally, our observations illustrate that the local structure of carbon is dependent on age-hardening during low-temperature aging.

Introduction Lithium-transition metal oxides with the layered rock-salt structure are widely used as cathodes for Li ion batteries (LIBs) which achieve high working voltage and high gravimetric/volumetric capacity. However, oxide-based cathodes may release oxygen during the battery operation, causing electrochemical degradation and side reactions between the cathode active material and organic liquid electrolytes. The side reactions are exothermic and can trigger thermal runaway in the worst case. To achieve both high energy density and safety, it is important to understand the mechanism of oxygen release from oxide-based cathode materials. In this work, we evaluated the oxygen release behavior in Li(Ni1/3Co1/3Mn1/3)O2 (NCM111) and Li(Ni0.5Co0.2Mn0.3)O2 (NCM523) by applying coulometric titration technique; crystal structure and charge compensation are discussed by analyzing X-ray diffraction and soft X-ray absorption spectroscopy. The highlight of this work is that the materials maintained the original layered structure with more than 3% oxygen loss, which is meaningful for providing complementary information to researchers who have interests on the thermochemical stability of NCM materials. Experimental NCM powders were synthesized by solid state reaction between carbonate precursors and LiOH·H2O. Oxygen release behavior was evaluated by coulometric titration using yttria stabilized zirconia as an oxide ion conductor. Samples with different oxygen deficiency were also prepared by coulometric titration method. X-ray diffraction (XRD) and Rietveld refinement were carried out on the pristine and oxygen deficient samples to evaluate the crystal structure variation. Soft X-ray absorption spectroscopy (SXAS) by the fluorescence yielding (FY) mode was performed to measure the transition metal L edge and investigate the charge compensation mechanism. Results and discussion Oxygen release behavior at 873 K of NCM111 is shown in Fig. (a). The vertical axis represents the molar ratio of the extracted oxygen from the sample and the sum of metals (Li, Ni, Co and Mn) in the structure. According to XRD, the sample accepted more than 3% oxygen deficiency without phase transition and decomposition. The XRD patterns and results of structure refinement would be shown in the presentation. The slope of the oxygen nonstoichiometric behavior is steep in the higher P(O2) region, moderate in the intermediate P(O2) region and becomes steep again in the lower P(O2) conditions. A plateau behavior at the middle P(O2) region was formed at around ΔO/M=-0.02. According to XAS, this compositional plateau is caused by the transition of redox species, Ni3+/Ni2+ redox in higher P(O2) region and Co3+/Co2+ transition in lower P(O2) region. Results of the crystal structure variation with oxygen deficiency was investigated by XRD and Rietveld refinement assuming structure. Fig. (b) and (c) are the lattice parameters and d-spacing of Li and transition metal slabs, respectively. Reduction expansion was clearly observed in NCM111. Although oxygen extraction induced the lattice expansion in all dimensions, the transition metal layers expanded and Li layers contracted by the introduction of oxygen deficiency. Structural changes due to oxygen deficiency narrows the space in Li slab, and may impede the Li diffusion. In the presentation, additional results of NCM523 will be shown and compared with NCM111 in detail, including cation mixing and charge compensation, as effects of oxygen deficiency concentration on the layered structure. Figure 1

Introduction Demands on high energy density batteries increase to exploit renewable energies efficiently and develop zero-emission vehicles [1]. Among technological issues for next-generation batteries, we focus on the development of cathode active materials. So far, oxide-based cathode materials have been used in lithium ion batteries because of their excellent electrochemical properties. However, the formation of oxygen defects like oxygen vacancy is inevitable in oxides. There are two important motivations for the study of oxygen defect formation in oxide-based cathodes, one is the safety of batteries and the other is the battery performance. For the safety, it was reported that the reaction between organic liquid electrolytes and released oxygen from oxide-based cathodes is exothermic and cause abnormal heat generation [2]. To prevent catastrophic thermal runaway of battery systems, understanding oxygen release mechanism is important. For the influence on battery performance, it was reported that preliminary reduction treatments for Li-rich cathodes improved capacity, rate capability and capacity retention [3]. To establish the guideline for the oxygen defect engineering for advanced battery materials, it is necessary to understand influences of oxygen defects on electrochemical properties. In the presentation, oxygen vacancy formation behavior in oxide-based cathodes and influences of oxygen vacancy on battery performances are discussed. Experimental Li1.2Mn0.6Ni0.2O2 and Li1.2Ni0.13Co0.13Mn0.54O2 were synthesized by solid state reaction of carbonate precursors and LiOH·H2O. The oxygen vacancy formation was evaluated by thermogravimetry and the coulometric titration using yttria stabilized zirconia. The absolute oxygen content of the sample was determined by iodometric titration. Samples with different oxygen vacancy concentration were also prepared by the coulometric titration method. Influences of oxygen vacancy on crystal and electronic structures were evaluated by X-ray diffraction (XRD) and soft X-ray absorption spectroscopy (XAS). Charge/discharge measurements were performed on the pristine and the oxygen-deficient cathodes. Results and discussion Figure 1 shows the variation of the oxygen content in Li1.2Mn0.6Ni0.2O2 and Li1.2Ni0.13Co0.13Mn0.54O2. In the figure, the vertical axis, O/M, represents the molar ratio of oxygen in and metal components (Li, Ni, Co and Mn) in the target material, meaning that O/M = 1 represents the oxygen stoichiometric composition for Li1.2Mn0.6Ni0.2O2 and Li1.2Ni0.13Co0.13Mn0.54O2, and the horizontal axis represents the equilibrium P(O2) for each oxygen content. With decreasing O/M, P(O2) decreased and reached a constant value regardless of the relative oxygen content. The oxygen nonstoichiometric data in Figure 1 can be roughly classified into two regions depending on the slope of the curve. In the higher P(O2) region where the O/M vs. log P(O2) curve showed a certain slope, meaning both oxygen content and P(O2) changes simultaneously. In the lower P(O2) region, on the other hand, P(O2) is almost invariant regardless of O/M. The high P(O2) region is the oxygen deficient nonstoichiometry region where the oxygen vacancies were randomly distributed in the oxide-based cathodes. On the contrary, the low P(O2) region is the multiphase co-existing region where the sample is decomposed by the electrochemical oxygen extraction and co-exist with the decomposition phases. In this case, the equilibrium P(O2) is fixed with that of the multiphase co-existing state regardless of apparent O/M. The reduction stability of Li1.2Mn0.6Ni0.2O2 and Li1.2Ni0.13Co0.13Mn0.54O2 were also confirmed by XRD. The reduction stability limit of Li1.2Mn0.6Ni0.2O2 and Li1.2Ni0.13Co0.13Mn0.54O2 were log(P(O2)/bar) = -17.7 and -20.7, respectively. From these evaluations, it can be concluded that Li1.2Mn0.6Ni0.2O2 and Li1.2Ni0.13Co0.13Mn0.54O2 can accept oxygen vacancy up to about 2 mol% and about 3 mol%, respectively. The results of XRD, XAS and battery tests will be shown in the presentation, and influences of oxygen defects on crystal and electronic structures and electrochemical performance will be discussed. References [1] J. M. Tarascon and M. Armand, Nature, 2001, 414, 359–367. [2] Q. Wang, P. Ping, X. Zhao, G. Chu, J. Sun and C. Chen, J. Power Sources, 2012, 208, 210–224. [3] K. Kubota, T. Kaneko, M. Hirayama, M. Yonemura, Y. Imanari, K. Nakane and R. Kanno, J. Power Sources, 2012, 216, 249–255. Figure 1