Posteucritic magmatism on Vesta: Evidence from the petrology and thermal history of diogenites

International audienceWe report on the petrology and the thermal histories of 13 diogenites in order to constrain the formation processes of the Vestan crust. We classify diogenites into unequilibrated and equilibrated diogenites in a scheme similar to that for basaltic eucrites. Pyroxenes in unequilibrated diogenites are chemically zoned, indicating that they crystallized rapidly from melts and escaped from global crustal metamorphism. The presence of unequilibrated diogenites casts doubt on the fact that all the diogenites formed at depth in the parent body, as commonly thought. Some diogenites probably crystallized in shallow intrusions or were extruded on the surface. These facts strengthen the geochemical evidence that diogenites and eucrites are not directly cogenetic and suggest that at least some diogenites have intruded the early formed eucritic crust. Thus, diogenites are certainly not the products of the crystallization of the magma ocean that triggered the differentiation of Vesta but are more likely cumulates associated with a later stage of magmatism. Furthermore, the intrusion of diogenites could have significantly thickened the early formed crust, making it difficult to excavate deep‐seated olivine mantle by moderate impact events

The Abundance and Distribution of Presolar Materials in Cluster IDPS

Presolar grains and remnants of interstellar organic compounds occur in a wide range of primitive solar system materials, including meteorites, interplanetary dust particles (IDPs), and comet Wild-2 samples. Among the most abundant presolar phases are silicate stardust grains and molecular cloud material. However, these materials have also been susceptible to destruction and alteration during parent body and nebular processing. In addition to their importance as direct samples of remote and ancient astrophysical environments, presolar materials thus provide a measure of how well different primitive bodies have preserved the original solar system starting materials

The JAMSTEC NanoSIMS 50L: Imaging mass spectrometry at the sub-micron scale for meteorite and biology samples

PPS22-P03ポスター要旨 / 日本地球惑星科学連合2012年大会（2012年5月20日～5月25日, 幕張メッセ国際会議場） / 日本惑星科学連合の許諾に基づき本文ファイルを掲

Submicrometer Organic Grains: Widespread Constituents of the Early Solar System

Primitive meteorites and interplanetary dust particles (IDPs) contain remants of interstellar organic matter, marked by anomalous H and N isotopic ratios. These isotopic anomalies are attributed to mass fractionation during chemical reactions at cryogenic temperatures (10-100K) in a cold molecular cloud. Significant variations in the chemistry and isotopic compositions of organic compounds within and between these samples suggest varying histories of alteration and dilution of the presolar components. Recent studies have reported large H and N isotopic anomalies preserved in sub-m organic inclusions in both meteorites and IDPs. In the Tagish Lake meteorite, the largest H and N isotopic anomalies are associated with sub-m, hollow organic globules. The common physical, chemical, and isotopic characteristics of these globules suggest that they formed before being incorporated into their parent meteorite. These organic globules probably originated as organic ice coatings that formed on preexisting ice or mineral grains in a cold molecular cloud. Radiation driven photochemistry may have processed them into refractory organic grains. This model implies that submicrometer organic grains were widely distributed throughout the solar nebula during the epoch of planet formation. Submicrometer organic particles were detected by the Giotto and Vega encounters with comet Halley, termed CHON particles based on their major element chemistry. The first direct samples of cometary dust (comet Wild-2) were returned by the Stardust spacecraft in January 2006. These samples exhibit widely varying, fine grained mineralogy similar to anhydrous IDPs, including submicrometer carbonaceous grains. The submicrometer organic grains from comet Wild-2 exhibit H and N isotopic anomalies of similar magnitude to those commonly observed in primitive meteorites and IDPs. Isotopically anomalous, submicrometer organic grains have now been observed in meteorites, IDPs, the Oort-cloud comet Halley, and the Kuiper-belt comet Wild-2, suggesting that such grains were prevalent throughout the protoplanetary disk

Discovery of natural MgSiO3 tetragonal garnet in a shocked chondritic meteorite

MgSiO3 tetragonal garnet, which is the last of the missing phases of experimentally predicted high-pressure polymorphs of pyroxene, has been discovered in a shocked meteorite. The garnet is formed from low-Ca pyroxene in the host rock through a solid-state transformation at 17 to 20 GPa and 1900° to 2000°C. On the basis of the degree of cation ordering in its crystal structure, which can be deduced from electron diffraction intensities, the cooling rate of the shock-induced melt veins from ~2000°C was estimated to be higher than 103°C/s. This cooling rate sets the upper bound for the shock-temperature increase in the bulk meteorite at ~900°C

H, C, and N isotopic compositions of Hayabusa category 3 organic samples

Since isotopic ratios of H, C, and N are sensitive indicators for determining extraterrestrial organics, we have measured these isotopes of Hayabusa category 3 organic samples of RB-QD04-0047-02, RA-QD02-0120, and RB-QD04-0001 with ion imaging using a NanoSIMS ion microprobe. All samples have H, C, and N isotopic compositions that are terrestrial within errors (approximately ±50‰ for H, approximately ±9‰ for C, and approximately ±2‰ for N). None of these samples contain micrometer-sized hot spots with anomalous H, C, and N isotopic compositions, unlike previous isotope data for extraterrestrial organic materials, i.e., insoluble organic matters (IOMs) and nano-globules in chondrites, interplanetary dust particles (IDPs), and cometary dust particles. We, therefore, cannot conclude whether these Hayabusa category 3 samples are terrestrial contaminants or extraterrestrial materials because of the H, C, and N isotopic data. A coordinated study using microanalysis techniques including Fourier transform infrared spectrometry (FT-IR), time-of-flight secondary ion mass spectrometry (ToF-SIMS), NanoSIMS ion microprobe, Raman spectroscopy, X-ray absorption near edge spectroscopy (XANES), and transmission electron microscopy/scanning transmission electron microscopy (TEM/STEM) is required to characterize Hayabusa category 3 samples in more detail for exploring their origin and nature.This research was supported by the JSPS Strategic Fund for Strengthening Leading-edge Research and Development to the JAMSTEC

A VCP modulator, KUS121, as a promising therapeutic agent for post-traumatic osteoarthritis

京大開発の薬剤「KUS121」の変形性膝関節症への効果を確認 --外傷性変形性関節症の治療薬として臨床応用へ--. 京都大学プレスリリース. 2020-12-17.Post-traumatic osteoarthritis (PTOA) is a major cause which hinders patients from the recovery after intra-articular injuries or surgeries. Currently, no effective treatment is available. In this study, we showed that inhibition of the acute stage chondrocyte death is a promising strategy to mitigate the development of PTOA. Namely, we examined efficacies of Kyoto University Substance (KUS) 121, a valosin-containing protein modulator, for PTOA as well as its therapeutic mechanisms. In vivo, in a rat PTOA model by cyclic compressive loading, intra-articular treatments of KUS121 significantly improved the modified Mankin scores and reduced damaged-cartilage volumes, as compared to vehicle treatment. Moreover, KUS121 markedly reduced the numbers of TUNEL-, CHOP-, MMP-13-, and ADAMTS-5-positive chondrocytes in the damaged knees. In vitro, KUS121 rescued human articular chondrocytes from tunicamycin-induced cell death, in both monolayer culture and cartilage explants. It also significantly downregulated the protein or gene expression of ER stress markers, proinflammatory cytokines, and extracellular-matrix-degrading enzymes induced by tunicamycin or IL-1β. Collectively, these results demonstrated that KUS121 protected chondrocytes from cell death through the inhibition of excessive ER stress. Therefore, KUS121 would be a new, promising therapeutic agent with a protective effect on the progression of PTOA

Microbial Metabolism and Community Dynamics in Hydraulic Fracturing Fluids Recovered From Deep Hydrocarbon-Rich Shale

Hydraulic fracturing is a prominent method of natural gas production that uses injected, high-pressure fluids to fracture low permeability, hydrocarbon rich strata such as shale. Upon completion of a well, the fluid returns to the surface (produced water) and contains natural gas, subsurface constituents, and microorganisms (Barbot et al., 2013; Daly et al., 2016). While the microbial community of the produced fluids has been studied in multiple gas wells, the activity of these microorganisms and their relation to biogeochemical activity is not well understood. In this experiment, we supplemented produced fluid with 13C-labeled carbon sources (glucose, acetate, bicarbonate, methanol, or methane), and 15N-labeled ammonium chloride in order to isotopically trace microbial activity over multiple day in anoxic incubations. Nanoscale secondary ion mass spectrometry (NanoSIMS) was used to generate isotopic images of 13C and 15N incorporation in individual cells, while isotope ratio monitoring–gas chromatography–mass spectrometry (IRM–GC–MS) was used to measure 13CO2, and 13CH4 as metabolic byproducts. Glucose, acetate, and methanol were all assimilated by microorganisms under anoxic conditions. 13CO2 production was only observed with glucose as a substrate indicating that catabolic activity was limited to this condition. The microbial communities observed at 0, 19, and 32 days of incubation did not vary between different carbon sources, were low in diversity, and composed primarily of the class Clostridia. The primary genera detected in the incubations, Halanaerobium and Fusibacter, are known to be adapted to harsh physical and chemical conditions consistent with those that occur in the hydrofracturing environment. This study provides evidence that microorganisms in produced fluid are revivable in laboratory incubations and retained the ability to metabolize added carbon and nitrogen substrates