Isotopic analysis of Fe has proved to be a productive tool for the study of the formation and evolution of planetary bodies. The Fe isotopic studies on the Moon revealed that low-Ti and high-Ti ...basalts are positively correlated with TiO2 contents, indicating the occurrence of Fe isotopic fractionation during lunar magma ocean differentiation (Weyer et al., 2005; Liu et al., 2010; Wang et al., 2015; Sossi and Moynier, 2017). If true, very low-Ti basalts may be more representative of the lunar mantle than high-Ti and low-Ti basalts. Thus, an Fe isotopic study of very low-Ti basalts is required to investigate the Fe isotopic evolution scenario during lunar magma ocean differentiation.
In this study, we measured Fe isotopic ratios of soil samples from the Soviet Luna missions, Luna 16, 20, and 24, using MC-ICP-MS. Bulk soil samples without isolation of components and separated monomineralic grains (olivine, pyroxene, and agglutinate) were dedicated for the Fe isotopic study. Among our samples, Luna 24 soil is recognized as very low-Ti basalt. Evidence of non-mass-dependent Fe isotopic fractionation was not found in bulk soils and separated monomineralic olivine, pyroxene, and agglutinate grains. Lunar regolith samples are weathered by meteorite impacts on the Moon’s surface. A mature regolith sample, L1613, showed clearly distinguished Fe isotopic compositions between the fine-grained fraction (δ57Fe = 0.54 ± 0.06‰) and the coarse-grained fraction (δ57Fe = 0.20 ± 0.06‰). Such Fe isotopic differences among different size fractions were smaller in the submature sample (L2001) and the immature sample (L24130.3). The Fe isotopic ratios of separated grains show that agglutinates have higher δ57Fe values than bulk and monomineralic grains, indicating abundant nanophase Fe in agglutinates and partial evaporation of Fe during its melting.
The δ57Fe value for the coarsest-grained fraction of L24130.3 was found to be 0.08 ± 0.04‰, which is the first Fe isotopic composition reported for lunar samples with very low-Ti mare basalt composition. This value is clearly lower than previously reported δ57Fe values for high-Ti and low-Ti basalts and is nearly identical to those of Mg-suite rocks. This observation is consistent with the Fe isotopic evolution model during lunar magma ocean differentiation (Sossi and Moynier, 2017). Our results related to very low-Ti basalt showed that the bulk silicate Moon has lower Fe isotopic composition than the value estimated from averaged low-Ti or high-Ti basalts.
Given the data known to date, including our results, we conclude that it is most likely that Earth and the Moon have the same Fe isotopic composition. We believe that isotopically heavy Fe of silicate Earth is balanced by isotopically light Fe of Earth’s core, as suggested by Galimov’s (2011) model for the formation of the Earth-Moon system.
This paper makes an analysis of black feminism in the album Bom mesmo e estar debaixo d'agua, of the singer Luedji Luna, from the concepts of "Crossroads" (Encruzilhada) (Martins, 2021), and Safe ...Spaces (Collins, 2019). The analisis take the images of "Chororo", "Ain't I a Woman?" and "Lencois" to discuss the process of self-definition (Collins, 2019) in the artist's body, that activate female-crossroads when walks by the time and the space.
Bulk composition data for 24 chemical elements are presented for regolith samples (<1 mm fines) from each of the 62 half‐centimeter dissection intervals along the 31 cm length of the 76001 vertical ...drive tube collected by astronauts at the base of the North Massif at station 6 of the Apollo 17 landing site. The core regolith is nearly uniform in composition with depth although the concentrations of Sc and Sm, for example, decrease from 28.5 μg g−1 Sc and 5.93 μg g−1 Sm at the top 2.5 cm to 26.9 μg g−1 Sc and 5.55 μg g−1 Sm at the bottom 2.5 cm. This change reflects an increase with depth in the relative abundance of Sm‐poor, feldspathic material, from 48.4% at the top to 50.1% at the bottom. On the basis of compositional mass balance, the feldspathic (nonmare) material of the station 6 regolith requires a substantial proportion of an Mg‐rich lithology, ~27% when modeled as troctolite sample 76535. The remaining 73% is nominally Sm‐poor anorthositic norite in composition. No such Mg‐rich component is required to account for the composition of the regolith of the South Massif (stations 2 and 3). The total feldspathic component of the North Massif regolith, normatively an anorthositic troctolite (74 vol% plagioclase, olivine:pyroxene = 55:45, Mg′ = 78%), is very similar to that of the nonmare component of the Luna 20 regolith collected 910 km to the southeast on the Crisium ejecta deposit. We also present new composition data for 21, 25, and 16 small lithic fragments (0.1–3.9 mg each) from the regoliths of the Luna 16, 20, and 24 missions.
Mi novela sería un homenaje, un espejo a Alsino (1922) y a su niño jorobado, linchado, enfermo, en el pináculo del delirio, Jesucristo: la muerte que cargo por arte de fcción.
The Woven EndoBridge (WEB) and other intrasaccular flow disruptors show promise in treating intracranial aneurysms. We performed a bibliometric analysis to provide novel insights into the trends and ...trajectory of these devices. We systematically assessed bibliometric data such as citations, journals, study designs, open access status, and multi-institutional involvement for the top-cited articles on WEB and other disruptors. The top 100 cited studies on the WEB had citations from 7 to 144 (mean ± standard deviation 35.6 ± 29.5), while only 33 studies were published for other intrasaccular flow disruptors (4.24 ± 8.45). Of the other devices, the Contour has the most publications (n = 21). Retrospective reviews were the most common study design for both WEB and other intrasaccular devices. France published the most studies in the top 100 WEB papers (n = 35), while Germany led for other flow disruptors (n = 10). In all studies analyzed, no senior authors from Africa are present. The top 100 WEB publications had a higher mean citation count (35.6 vs. 4.24, P<0.001), higher mean citations per year (5.24 vs. 1.03, P<0.01), and a higher proportion of multi-institutional collaborations (44.0% vs. 12.1%, P<0.01) than other intrasaccular flow disruptors. In conclusion, countries with the most publications on WEB are not necessarily the ones leading the way with newer intrasaccular devices, while study designs remain similar. There is a limited contribution to the literature outside of Europe and North America. Our findings identify notable collaborators and trends, providing a snapshot of the field and a roadmap for future research.
We quantitatively describe the main events that led to the Terra project’s failure in May 2022. We first review, in a systematic way, news from heterogeneous social media sources; we discuss the ...fragility of the Terra project and its vicious dependence on the Anchor protocol. We hence identify the crash’s trigger events, analysing hourly and transaction data for Bitcoin, Luna, and TerraUSD. Finally, using state-of-the-art techniques from network science, we study the evolution of dependency structures for 61 highly capitalised cryptocurrencies during the down-market and we also highlight the absence of herding behaviour analysing cross-sectional absolute deviation of returns.
•We describe the Terra project’s features and the mechanisms that led to its failure.•We use network science and herding approaches to capture dependency structures.•The vicious dependence of the Terra project on the Anchor protocol is reported.•We uncover BTC’s reference role during the first phase of the collapse.•Herding behaviour is not detected during the down market.
Space exploration missions have placed renewed focus on the South Circumpolar Region (SCR) of the Moon due to its unexplored nature by landed missions, potential water resources, proximity to the ...ancient South Pole-Aitken (SPA) basin, and the presence of regions that provide near-permanent solar illumination. Unlike previous surface exploration sites, the SCR lacks extensive mare regions and is most similar to the Apollo 16 and Luna 20 sites, and is dominated by overlapping deposits of impact craters and basins of a wide range of sizes and ages. This renders the geologic history of individual regions difficult to determine, and the provenance of returned samples potentially enigmatic. In order to help alleviate these problems and to provide a consistent geological framework for landing site selection, mission planning and operations, and interpreting sample provenance, we have compiled a new geologic map of the SCR (1:300000 mapping scale; South pole to 70°S) using the most recently acquired orbital data (LRO LROC WAC 100 m/pix resolution image data and LOLA-based 80–20 m/pix resolution DTMs), and portraying geological units, features and structures, stratigraphic sequences, and providing a framework to address many outstanding problems in lunar science. We define and map several major types of units and structures: (1) high-standing massifs of the SPA basin, (2) crater-related units – walls, rims, and ejecta of impact craters and smaller basins, (3) plains units of both impact (impact melt and/or Cayley Formation) and volcanic origins (lava fields and pyroclastic deposits) and (4) landforms related to degradation of crater topography. Absolute Model Ages (AMAs) derived from crater size-frequency distribution (CSFD) measurements for ∼200 of these units/structures, whose relative ages were determined by superposition relations, were used to compile a correlation of map units for the SCR region.
