Elsevier BV Acta Medica Okayama 2590-1974 27 2025 Development of a technique to identify μm-sized organic matter in asteroidal material: An approach using machine learning 100277 EN Rahul Kumar The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Katsura Kobayashi The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Christian Potiszil The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Tak Kunihiro The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Asteroidal materials contain organic matter (OM), which records a number of extraterrestrial environments and thus provides a record of Solar System processes. OM contain essential compounds for the origin of life. To understand the origin and evolution of OM, systematic identification and detailed observation using in-situ techniques is required. While both nm- and μm-sized OM were studied previously, only a small portion of a given sample surface was investigated in each study. Here, a novel workflow was developed and applied to identify and classify μm-sized OM on mm-sized asteroidal materials. The workflow involved image processing and machine learning, enabling a comprehensive and non-biased way of identifying, classifying, and measuring the properties of OM. We found that identifying OM is more accurate by classification with machine learning than by clustering. On the approach of classification with machine learning, five algorithms were tested. The random forest algorithm was selected as it scored the highest in 4 out of 5 accuracy parameters during evaluation. The workflow gave modal OM abundances that were consistent with those identified manually, demonstrating that the workflow can accurately identify 1-15 μm-sized OM. The size distribution of OM was modeled using the power-law distribution, giving slope α values that were consistent with fragmentation processes. The shape of the OM was quantified using circularity and solidity, giving a positive correlation and indicating these properties are closely related. Overall, the workflow enabled identification of many OM quickly and accurately and the obtainment of chemical and petrographic information. Such information can help the selection of OM for further in-situ techniques, and elucidate the origin and evolution of OM preserved in asteroidal materials. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 0016-7037 400 2025 Lithium- and oxygen-isotope compositions of a Si-rich nebular reservoir determined from chondrule constituents in the Sahara 97103 EH3 chondrite 51 71 EN Torii Douglas-Song The Pheasant Memorial Laboratory Institute for Planetary Materials, Okayama University Tsutomu Ota The Pheasant Memorial Laboratory Institute for Planetary Materials, Okayama University Masahiro Yamanaka The Pheasant Memorial Laboratory Institute for Planetary Materials, Okayama University Hiroshi Kitagawa The Pheasant Memorial Laboratory Institute for Planetary Materials, Okayama University Ryoji Tanaka The Pheasant Memorial Laboratory Institute for Planetary Materials, Okayama University Christian Potiszil The Pheasant Memorial Laboratory Institute for Planetary Materials, Okayama University Tak Kunihiro The Pheasant Memorial Laboratory Institute for Planetary Materials, Okayama University Here we report the in situ ion-microprobe analyses of the Li- and O-isotope compositions of enstatite, FeO-rich pyroxene, olivine, glass, and cristobalite grains from six chondrule-related objects from the Sahara 97103 EH3 chondrite. The O-isotope composition of the enstatite grains scattered around the intersection between the terrestrial fractionation and primitive chondrule minerals lines. Whereas, that of olivine varied along the primitive chondrule minerals line. Based on the mineralogy, we found cristobalite formed as a result of Si saturation, instead of the reduction of FeO-rich silicates, consistent with Si-enrichment of whole rock enstatite chondrites. Based on the mineralogy and O-isotope compositions, we infer that olivines in some chondrules are relict grains. In chondrules that contained olivine, no abundant niningerite [(Mg,Fe,Mn)S] was observed. Thus, enstatite formation can be explained by the interaction of an olivine precursor with additional SiO2 (Mg2SiO4 + SiO2 → Mg2Si2O6), instead of sulfidation (Mg2SiO4 + S → 1/2 Mg2Si2O6 + MgS + 1/2 O2). Using the equation Mg2SiO4 + SiO2 → Mg2Si2O6 and the O-isotope compositions of enstatite and olivine, the O-isotope composition of the additional SiO2 was estimated. Based on the O-isotope composition, we infer that there could be a Si-rich gas with an elevated Δ17O value similar to, or greater than the second trend line (Δ17O = 0.9 ‰) suggested by Weisberg et al. (2021), during chondrule formation. The variation in the Li-isotope compositions of enstatite and olivine grains from EH3 chondrules is smaller than that for the same phases from CV3 chondrules. The variation in the Li-isotope compositions of the enstatite and olivine grains from EH3 chondrules is also smaller than that of their O-isotope compositions. During the recycling of enstatite-chondrite chondrules, both Li- and O-isotope compositions were homogenized. Although enstatite is the major carrier of Li in EH3 chondrules, the Li-isotope composition (δ7Li) of enstatite is lower than that of whole rock EH3 chondrites, suggesting the existence of a phase with higher δ7Li. Meanwhile, the Li-isotope composition and concentration (δ7Li, [Li]) of enstatite is higher than that of olivine. The Li-isotope composition of the Si-rich gas was estimated to be δ7Li = 1 ‰, using a similar mass-balance calculation as applied for the O-isotope composition. The Li-isotope composition of the Si-rich gas from the enstatite-chondrite-chondrule forming-region, is consistent with that of whole rock EH3 chondrites, and differs significantly from that of the Si-rich gas from the carbonaceous-chondrite-chondrule forming-region (δ7Li = −11 ‰) determined by a previous study. We speculate that the Si-rich gas in the carbonaceous-chondrite-chondrule forming-region maintained the Li-isotope heterogeneity inherited from light lithium synthesized by galactic cosmic-ray spallation in the interstellar medium. No potential conflict of interest relevant to this article was reported.

Elsevier BV Acta Medica Okayama 0012-821X 653 2025 Meteoritic and asteroidal amino acid heterogeneity: Implications for planetesimal alteration conditions and sample return missions 119205 EN Christian Potiszil Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Tsutomu Ota Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Masahiro Yamanaka Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Katsura Kobayashi Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Ryoji Tanaka Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Eizo Nakamura Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Carbonaceous chondrites (CC) and asteroid return samples contain amino acids (AA), which are essential for an origin of life on the early Earth and can provide important information concerning planetesimal alteration processes. While many studies have investigated AA from CC, separate studies have often found differing abundances for the same meteorite. Accordingly, analytical bias, differing terrestrial contamination levels and intrinsic sample heterogeneity have been proposed as potential reasons. However, current analytical techniques allow for the analysis of several mg-sized samples and can thus enable an investigation of AA heterogeneity within single meteorite specimens. Here, such an analytical technique is applied to characterise the AA in triplicate aliquots of three CCs. The results indicate that CCs are heterogenous in terms of their AA at the mm-scale. Furthermore, the results help to further constrain the effects of planetesimal alteration on organic matter and the requirements of future sample return missions that aim to obtain organic-bearing extraterrestrial materials. No potential conflict of interest relevant to this article was reported.

American Astronomical Society Acta Medica Okayama 0004-637X 965 1 2024 Unraveling the Cr Isotopes of Ryugu: An Accurate Aqueous Alteration Age and the Least Thermally Processed Solar System Material 52 EN Ryoji Tanaka The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Dilan M. Ratnayake The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Tsutomu Ota The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Noah Miklusicak The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Tak Kunihiro The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Christian Potiszil The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Chie Sakaguchi The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Katsura Kobayashi The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Hiroshi Kitagawa The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Masahiro Yamanaka The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Masanao Abe Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Akiko Miyazaki Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Aiko Nakato Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Satoru Nakazawa Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Masahiro Nishimura Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Tatsuaki Okada Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Takanao Saiki Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Satoshi Tanaka Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Fuyuto Terui Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Yuichi Tsuda Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Tomohiro Usui Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Sei-ichiro Watanabe Department of Earth and Planetary Sciences, Nagoya University Toru Yada Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Kasumi Yogata Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Makoto Yoshikawa Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency Eizo Nakamura The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University The analysis of samples returned from the C-type asteroid Ryugu has drastically advanced our knowledge of the evolution of early solar system materials. However, no consensus has been obtained on the chronological data, which is important for understanding the evolution of the asteroid Ryugu. Here, the aqueous alteration age of Ryugu particles was determined by the Mn–Cr method using bulk samples, yielding an age of 4.13 + 0.62/−0.55 Myr after the formation of Ca–Al-rich inclusions (CAI). The age corresponds to 4563.17 + 0.60/−0.67 Myr ago. The higher 55Mn/52Cr, ε54Cr, and initial ε53Cr values of the Ryugu samples relative to any carbonaceous chondrite samples implies that its progenitor body formed from the least thermally processed precursors in the outermost region of the protoplanetary disk. Despite accreting at different distances from the Sun, the hydrous asteroids (Ryugu and the parent bodies of CI, CM, CR, and ungrouped C2 meteorites) underwent aqueous alteration during a period of limited duration (3.8 ± 1.8 Myr after CAI). These ages are identical to the crystallization age of the carbonaceous achondirtes NWA 6704/6693 within the error. The ε54Cr and initial ε53Cr values of Ryugu and NWA 6704/6693 are also identical, while they show distinct Δ'17O values. This suggests that the precursors that formed the progenitor bodies of Ryugu and NWA 6703/6693 were formed in close proximity and experienced a similar degree of thermal processing in the protosolar nebula. However, the progenitor body of Ryugu was formed by a higher ice/dust ratio, than NWA6703/6693, in the outer region of the protoplanetary disk. No potential conflict of interest relevant to this article was reported.

BMC Acta Medica Okayama 1743-8977 20 1 2023 An investigation of the internal morphology of asbestos ferruginous bodies: constraining their role in the onset of malignant mesothelioma 19 EN Maya-Liliana Avramescu The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Christian Potiszil The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Tak Kunihiro The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Kazunori Okabe Bell Land General Hospital Eizo Nakamura The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University Background　Asbestos is a fibrous mineral that was widely used in the past. However, asbestos inhalation is associated with an aggressive type of cancer known as malignant mesothelioma (MM). After inhalation, an iron-rich coat forms around the asbestos fibres, together the coat and fibre are termed an "asbestos ferruginous body" (AFB). AFBs are the main features associated with asbestos-induced MM. Whilst several studies have investigated the external morphology of AFBs, none have characterised the internal morphology. Here, cross-sections of multiple AFBs from two smokers and two non-smokers are compared to investigate the effects of smoking on the onset and growth of AFBs. Morphological and chemical observations of AFBs were undertaken by transmission electron microscopy, energy dispersive x-ray spectroscopy and selected area diffraction.<br> Results　The AFBs of all patients were composed of concentric layers of 2-line or 6-line ferrihydrite, with small spherical features being observed on the outside of the AFBs and within the cross-sections. The spherical components are of a similar size to Fe-rich inclusions found within macrophages from mice injected with asbestos fibres in a previous study. As such, the spherical components composing the AFBs may result from the deposition of Fe-rich inclusions during frustrated phagocytosis. The AFBs were also variable in terms of their Fe, P and Ca abundances, with some layers recording higher Fe concentrations (dense layers), whilst others lower Fe concentrations (porous layers). Furthermore, smokers were found to have smaller and overall denser AFBs than non-smokers.<br> Conclusions　The AFBs of smokers and non-smokers show differences in their morphology, indicating they grew in lung environments that experienced disparate conditions. Both the asbestos fibres of smokers and non-smokers were likely subjected to frustrated phagocytosis and accreted mucopolysaccharides, resulting in Fe accumulation and AFB formation. However, smokers' AFBs experienced a more uniform Fe-supply within the lung environment compared to non-smokers, likely due to Fe complexation from cigarette smoke, yielding denser, smaller and more Fe-rich AFBs. Moreover, the lack of any non-ferrihydrite Fe phases in the AFBs may indicate that the ferritin shell was intact, and that ROS may not be the main driver for the onset of MM. No potential conflict of interest relevant to this article was reported.

Elsevier B.V. Acta Medica Okayama 0012-821X 574 15 2021 Heterogeneity within refractory organic matter from CM2 Carbonaceous Chondrites: Evidence from Raman spectroscopy 117149 EN Christian Potiszil Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University Wren Montgomery Imaging and Analysis Centre, The Natural History Museum Mark A. Sephton Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London CM2 chondrites experienced widespread aqueous and short term thermal alteration on their parent bodies. Whilst previous Raman spectroscopic investigations have investigated insoluble organic matter (IOM), they have not taken into account the binary nature of IOM. Studies employing mass spectrometry have indicated that IOM also known as macromolecular organic matter (MOM) is in fact composed of two distinct fractions: labile organic matter (LOM) and refractory organic matter (ROM). The ROM component represents the aromatic rich and heteroatom poor component of IOM/MOM, whilst the LOM fraction represents a more heteroatom and aliphatic rich component. Here we report Raman 2D maps and spectroscopic data for Murchison and Mighei, both before and after chemical degradation, which attacks and liberates LOM. The removal of LOM simulates the effects of aqueous alteration, where ester and ether bonds are broken and is thought to release some components to the soluble organic matter (SOM) fraction, also known as the free organic matter fraction (FOM). Raman spectroscopy can be used to reveal the nature of bonding (sp2and sp3) within carbonaceous materials such as meteoritic organic matter, through evaluation of the D and G band peak centres and FWHM values from the recorded data. The presence of sp3orbitals indicates that the organic materials contain aliphatic linkages and/or heteroatoms. Statistical analysis of the Raman parameters obtained here indicates that the organic matter originating the Raman response is indistinguishable between the bulk (chemically untreated) and chemically degraded (treated with KOH and HI) samples. Such an observation indicates that the ROM fraction is the major contributor to the Raman response of meteoritic organic matter and thus Raman spectroscopy is unlikely to record any aqueous alteration processes that have affected meteoritic organic matter. Therefore, studies which use Raman to probe the IOM are investigating just one of the components of IOM and not the entire fraction. Studies that aim to investigate the effects of aqueous alteration on meteoritic organic matter should use alternate techniques to Raman spectroscopy. Furthermore, the indistinguishable nature of the Raman response of ROM from Murchison and Mighei suggests these meteorites inherited a ROM component that is chemically similar, reflecting either a common process for the formation of CM2 meteoritic ROM and/or that these meteorites probed the same ROM reservoir. No potential conflict of interest relevant to this article was reported.