Speciation of cesium in a radiocesium-bearing microparticle emitted from Unit 1 during the Fukushima nuclear accident by XANES spectroscopy using transition edge sensor.

The chemical state of radiocesium (RCs) was determined using X-ray absorption near-edge structure (XANES) in fluorescence mode and microbeam X-ray fluorescence (μ-XRF) mapping for the cesium (Cs) incorporated in a radiocesium-bearing silica microparticle (CsMP) that was released during the Fukushima Dai-ichi Nuclear Power Plant accident in 2011. The sample investigated here was classified as a CsMP emitted from Unit 1 (diameter: approximately 500 µm; Cs weight concentration: approximately 50 µg/g). The Cs Lα emission from this Type-B CsMP with a much lower Cs concentration than those of calcium and titanium was difficult to detect using a silicon drift detector, severely decreasing the signal-to-background ratio of the Cs Lα emission.

Reduction of Membrane-derived Noise Using Beam-tilt Measurement and Deep Learning in Observation using Environmental Cell.

Electron microscopy using an environmental cell is a powerful tool for observing catalysts and other nanomaterials in gases and liquids. An environmental cell must contain amorphous silicon-nitride membranes because they protect the sample environment from the vacuum of the electron microscope and enable the electron beam to pass through the cell. However, the membranes superimpose non-uniform contrast on the projected image, degrading image quality.

A comparison between hollow cone illumination and wavelet transform methods for chromatin fiber orientation measurement.

Nucleosomes are proven to be the fundamental unit of chromosome structure. The stacking and folding of the nucleosome fibers within a chromosome is not fully understood. One of the reasons for the incomplete understanding of chromosome internal structure is that a nucleosome, about 11 nm in diameter, can not be resolved within the large chromatids (∼ 700 nm diameter) of a chromosome.

Confocal micro-X-ray fluorescence and total reflection X-ray fluorescence analyses of Ryugu sample in a laboratory environment.

This study analyzed Ryugu samples utilizing confocal micro-X-ray fluorescence (CM-XRF) and total reflection X-ray fluorescence (TXRF), in which information of elemental mapping as well as the content of trace elements could be obtained separately, and respectively. In CM-XRF, polycapillary lenses are placed in front of the X-ray tube and detector, and elemental information in the overlapping region of both focus points was obtained. Three-dimensional elemental distributions could be obtained by scanning a sample; the Ryugu sample was placed on an Al plate with one center, and the images of Fe, Ni, Cr, and Ca were obtained.

Adsorption structures and bonding states of cesium and barium adsorbed on various sites of vermiculite.

The adsorption reaction on clay minerals is crucial for understanding the environmental behavior of various cations, including cesium (Cs). However, its details remain unclear because of multiple adsorption sites of the clay minerals, a significant difference between concentrations in the atomic-scale experiments and the actual environment, and difficulties of evaluating bonding states of the adsorbed cations. It is expected that systematic experiments at the atomic-scale with a wide concentration range and application of density functional theory (DFT) calculations overcome the problems and bring crucial insights to link laboratory experiment results with environmental sample analysis.

Triplet-Excited Riboflavin Promotes Labile Fe(III) Accumulation and Changes Mineralization Pathways in Fe(II)-Catalyzed Ferrihydrite Transformation.

Flavins are well-known endogenous electron shuttles that facilitate long-distance extracellular electron transfer in dissimilatory iron reduction (DIR), but the effects of their photosensitivity on DIR and the transformation of metastable iron (oxyhydr)oxides like ferrihydrite (Fh) remain underexplored. This study compared the kinetics, pathways, and products of Fh transformation catalyzed by aqueous Fe(II) (Fe(II)) in the presence of oxidized riboflavin (RF) at pH 7 under both dark and light conditions. While RF has a negligible impact on Fe(II)-catalyzed Fh transformation in the dark, its photoexcited triplet state (RF*) can significantly accelerate interfacial electron transfer (IET) from Fe(II) to Fh, increasing the reductive dissolution rate of Fh and boosting the accumulation rate of the key intermediate labile Fe(III) (Fe(III)) from 14.

Resolution improvement of differential phase-contrast microscopy via tilt-series acquisition for environmental cell application.

A simple method that improves the resolution of phase measurement in differential phase-contrast scanning transmission electron microscopy for closed-type environmental cell applications was developed and tested using a model sample simulating environmental cell observations. Because the top and bottom membranes of an environmental cell are typically far apart, the images from these membranes are shifted widely by tilt-series acquisition, and averaging the images after alignment can effectively eliminate undesired signals from the membranes while improving the signal from the object of interest. It was demonstrated that a phase precision of 2π/100 rad is well achievable using the proposed method for the sample in an environmental cell.

Variations of organic functional chemistry in carbonaceous matter from the asteroid 162173 Ryugu.

Primordial carbon delivered to the early earth by asteroids and meteorites provided a diverse source of extraterrestrial organics from pre-existing simple organic compounds, complex solar-irradiated macromolecules, and macromolecules from extended hydrothermal processing. Surface regolith collected by the Hayabusa2 spacecraft from the carbon-rich asteroid 162173 Ryugu present a unique opportunity to untangle the sources and processing history of carbonaceous matter. Here we show carbonaceous grains in Ryugu can be classified into three main populations defined by spectral shape: Highly aromatic (HA), Alkyl-Aromatic (AA), and IOM-like (IL).

Solid-liquid partitioning and speciation of Pb(II) and Cd(II) on goethite under high pH conditions, as examined by subnanomolar heavy metal analysis, X-ray absorption spectroscopy, and surface complexation modeling.

The adsorption of heavy metals on iron oxides generally increases with pH and is almost complete at neutral to slightly alkaline pH. However, almost complete adsorption on a linear scale does not imply sufficient removal of the heavy metals in terms of their toxicity. Here, we elucidated the chemical reactions that determine the solid-liquid partitioning of Pb(II) and Cd(II) on goethite at high pH.

Simultaneous observation of multiple interferograms with Mach-Zehnder type electron interferometer on a 1.2-MV field-emission transmission electron microscope.

We developed a Mach-Zehnder type electron interferometer (MZ-EI) that enables simultaneous observation of interferograms created at multiple output locations on a 1.2-MV field-emission transmission electron microscope. This MZ-EI is composed of two single-crystal thin films, a lens located between the single-crystal thin films and imaging lenses.

Application of transition-edge sensors for micro-X-ray fluorescence measurements and micro-X-ray absorption near edge structure spectroscopy: a case study of uranium speciation in biotite obtained from a uranium mine.

In this study, we successfully applied a transition-edge sensor (TES) spectrometer as a detector for microbeam X-ray measurements from a synchrotron X-ray light source in the hard X-ray region to determine uranium (U) distribution at the micro-scale and its chemical species in biotite obtained from a U mine. It is difficult to separate the fluorescent X-ray of the U Lα line at 13.615 keV from that of the Rb Kα line at 13.

Microbially formed Mn(IV) oxide as a novel adsorbent for removal of Radium.

Radioactivity of Ra isotopes in natural waters is of serious concern. Control of Ra concentrations in tailings ponds, which store waste from U ore extraction processes, is an important issue in mill tailings management. In this study, we tested microbially formed Mn(IV) oxide as an adsorbent for removal of Ra in water treatment.

Size-classified aerosol-bound heavy metals and their effects on human health risks in industrial and remote areas in Japan.

Airborne aerosols were collected in six size classes (PM, PM, PM, PM, PM and PM) to investigate aerosol health risks in remote and industrial areas in Japan. We focused on heavy metals and their water-dispersed fractions. The average concentration of heavy metals was 18 ± 25-86 ± 48 ngm for PM, 46 ± 19-154 ± 80 for PM ngm, 98 ± 49-422 ± 186 ngm for PM, 321 ± 305-1288 ± 727 ngm for PM and 65 ± 52-914 ± 339 ngm or PM, and these concentrations were higher in industrial areas.

Removal of phase residues in electron holography.

Electron holography provides quantitative phase information regarding the electromagnetic fields and the morphology of micro- to nano-scale samples. A phase image reconstructed numerically from an electron hologram sometimes includes phase residues, i.e.

Bloch Point Quadrupole Constituting Hybrid Topological Strings Revealed with Electron Holographic Vector Field Tomography.

Topological magnetic (anti)skyrmions are robust string-like objects heralded as potential components in next-generation topological spintronics devices due to their low-energy manipulability via stimuli such as magnetic fields, heat, and electric/thermal current. While these 2D topological objects are widely studied, intrinsically 3D electron-spin real-space topology remains less explored despite its prevalence in bulky magnets. 2D-imaging studies reveal peculiar vortex-like contrast in the core regions of spin textures present in antiskyrmion-hosting thin plate magnets with S crystal symmetry, suggesting a more complex 3D real-space structure than the 2D model suggests.

Reassigning CI chondrite parent bodies based on reflectance spectroscopy of samples from carbonaceous asteroid Ryugu and meteorites.

The carbonaceous asteroid Ryugu has been explored by the Hayabusa2 spacecraft to elucidate the actual nature of hydrous asteroids. Laboratory analyses revealed that the samples from Ryugu are comparable to unheated CI carbonaceous chondrites; however, reflectance spectra of Ryugu samples and CIs do not coincide. Here, we demonstrate that Ryugu sample spectra are reproduced by heating Orgueil CI chondrite at 300°C under reducing conditions, which caused dehydration of terrestrial weathering products and reduction of iron in phyllosilicates.

Extreme accumulation of ammonia on electroreduced mackinawite: An abiotic ammonia storage mechanism in early ocean hydrothermal systems.

An increasing amount of evidence suggests that early ocean hydrothermal systems were sustained sources of ammonia, an essential nitrogen species for prebiotic synthesis of life's building blocks. However, it remains a riddle how the abiotically generated ammonia was retained at the vent-ocean interface for the subsequent chemical evolution. Here, we demonstrate that, under simulated geoelectrochemical conditions in early ocean hydrothermal systems ([Formula: see text][Formula: see text] V versus the standard hydrogen electrode), mackinawite gradually reduces to zero-valent iron ([Formula: see text]), generating interlayer [Formula: see text] sites.

Spontaneous Vortex-Antivortex Pairs and Their Topological Transitions in a Chiral-Lattice Magnet.

The spontaneous formation and topological transitions of vortex-antivortex pairs have implications for a broad range of emergent phenomena, for example, from superconductivity to quantum computing. Unlike magnets exhibiting collinear spin textures, helimagnets with noncollinear spin textures provide unique opportunities to manipulate topological forms such as (anti)merons and (anti)skyrmions. However, it is challenging to achieve multiple topological states and their interconversion in a single helimagnet due to the topological protection for each state.

Radiation makes cells select the form of death dependent on external or internal exposure: apoptosis or pyroptosis.

Internal radiation exposure from neutron-induced radioisotopes environmentally activated following atomic bombing or nuclear accidents should be considered for a complete picture of pathologic effects on survivors. Acute and localized high dose radiation exposure from hot particles taken into the body must induce cell death and severe damage to tissues, whether they are proliferating or not. However, very little the cellular and molecular mechanisms underlying this internal radiation pathology has been investigated.

Adsorption of cesium and strontium on mesoporous silicas.

Studies are underway on the adsorption reactions of metal ions in confined spaces at the solid-water interface, but it is unclear how the effects of confinement differ for different types of ions. We investigated the effect of the pore size on the adsorption of two cations with different valence, Cs and Sr, on mesoporous silicas with different pore size distributions. The amount of Sr adsorbed per unit surface area did not differ significantly among the silicas, whereas that of Cs was particularly high for silicas with a larger fraction of micropores.

Reversible adsorption of iridium in lyophilized cells of the unicellular red alga .

Iridium (Ir) is one of the rarest elements in the Earth's crust and is valuable in industry due to its high corrosion resistance. In this study, we used lyophilized cells of a unicellular red alga, for the selective recovery of small amounts of Ir from hydrochloric acid (HCl) solutions. The Ir recovery efficiency of the lyophilized cells was higher than that of activated carbon and comparable to that of an ion-exchange resin in up to 0.

Tissue-variation of iron stable isotopes in marine fish coupled with speciation analysis using X-ray absorption fine structure.

The Fe stable isotope ratio (δFe) in tissues is a potential parameter for examining the Fe metabolism in marine fish. Although the effect of ferritin storage has been proposed as a possible cause of heavy isotope (Fe) enrichment in the liver, no speciation and stable isotope ratio coupling data are available. Here, we report the δFe values measured by multicollector ICP-MS and the result of Fe K-edge X-ray absorption near-edge structure (XANES) analysis of multiple tissues obtained from a skipjack tuna (Katsuwonus pelamis) and a chub mackerel (Scomber japonicus).

Speciation of Zn and Cd in sierozem soil, northwest China: bulk EXAFS and micro synchrotron X-ray fluorescence.

Previous research studies have confirmed that Zn and Cd are the most predominant heavy metals in the Baiyin district, Gansu province, China. Furthermore, the speciation of Zn and Cd is a key factor in controlling the mobility, bioavailability, and toxicity of metals in Zn/Cd co-contaminated soil. In this study, the speciation of Zn and Cd in different types of agricultural soils including the Yellow River irrigated soil (s3) and sewage irrigated soil (s1 and s2) was investigated and compared by a combination of sequential extraction, bulk X-ray absorption fine structure (XAFS), and micro-X-ray fluorescence (μ-XRF) techniques.

Macromolecular organic matter in samples of the asteroid (162173) Ryugu.

Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water).