First classification of iron meteorite fragment preserved in Chang'e-5 lunar soils.

Lunar soil preserves numerous fragments of meteorites impacting on the Moon, providing a unique opportunity to investigate the distribution of the types of projectiles over billions of years. Here we report the first discovery of an iron meteorite fragment from the Chang'e-5 lunar soil, which consists mainly of martensite (quenched from taenite), kamacite, and schreibersite, with a trace of pentlandite. The meteorite fragment is Ni- and P-rich, S-poor, and based on its mineral chemistry and bulk composition, can be classified into the IID-group, a rare and carbonaceous group of iron meteorite originating in the outer Solar System. This meteorite fragment experienced only limited partial melting followed by fast cooling, suggestive of efficient preservation of intact remnants of iron meteorites impacting on the porous lunar regolith. Alternatively, it is a relic of a low-velocity impact of submillimeter-sized metal grains originated from an IID-like iron meteorite. Our observations demonstrate that it is feasible to achieve the type distribution of meteorites impacting on the Moon via systematically analyzing a large number of metal grains separated from lunar soils, thus shedding light on the dynamic evolution of the Solar System.

High abundance of solar wind-derived water in lunar soils from the middle latitude.

Remote sensing data revealed that the presence of water (OH/H2O) on the Moon is latitude-dependent and probably time-of-day variation, suggesting a solar wind (SW)-originated water with a high degassing loss rate on the lunar surface. However, it is unknown whether or not the SW-derived water in lunar soil grains can be preserved beneath the surface. We report ion microprobe analyses of hydrogen abundances, and deuterium/hydrogen ratios of the lunar soil grains returned by the Chang'e-5 mission from a higher latitude than previous missions. Most of the grain rims (topmost ~100 nm) show high abundances of hydrogen (1,116 to 2,516 ppm) with extremely low δD values (-908 to -992‰), implying nearly exclusively a SW origin. The hydrogen-content depth distribution in the grain rims is phase-dependent, either bell-shaped for glass or monotonic decrease for mineral grains. This reveals the dynamic equilibrium between implantation and outgassing of SW-hydrogen in soil grains on the lunar surface. Heating experiments on a subset of the grains further demonstrate that the SW-implanted hydrogen could be preserved after burial. By comparing with the Apollo data, both observations and simulations provide constraints on the governing role of temperature (latitude) on hydrogen implantation/migration in lunar soils. We predict an even higher abundance of hydrogen in the grain rims in the lunar polar regions (average ~9,500 ppm), which corresponds to an estimation of the bulk water content of ~560 ppm in the polar soils assuming the same grain size distribution as Apollo soils, consistent with the orbit remote sensing result.

[Effect of the course of posterior semicircular canal benign paroxysmal positional vertigo on residual symptoms after successful canalith repositioning procedure].

Objective:To investigate the effect of the course of posterior semicircular canal benign paroxysmal positional vertigo（BPPV） on residual symptoms after successful canalith repositioning procedure（CRP）. Methods:A total of 56 patients with posterior semicircular canal BPPV were selected from July 2020 to March 2021. They were divided into the short course group and the long course group according to the duration of disease from symptom onset to CRP treatment. All patients were treated with mechanical Epley repositioning procedure with rotary chair assistance. After successful repositioning treatment, they were followed up for seven to ten days. All patients were assessed using the vertigo disorder scale （DHI） before and after treatment,the differences of each dimension score and total score of DHI before and after successful CRP were compared between these two groups. Results:① After successful CRP, in patients with mild residual symptoms, the ratio between short course group and long course group were 68.6% and 31.4%, respectively. While in patients with moderate to severe residual symptoms,the ratio between short course group and long course group was 20% and 80%, respectively. The difference was statistically significant（P<0.05）. ②Before CRP, there was no significant difference in Physical dimension（DHI-P, 7 items） and in Function dimension（DHI-F, 9 items） between the two groups（P>0.05）, but there was significant difference in Emotion dimension（DHI-E, 9 items） and in total DHI score between the two groups（P<0.05, respectively）. After treatment, there was no significant difference in DHI-P score between the two groups（P>0.05）, but there were significant differences in DHI-F, DHI-E and DHI total score between the two groups（P<0.05,respectively）. Compared with the scores of DHI-P, DHI-F, DHI-E and DHI total score before and after successful CRP, the significant differences were found between the short course group and long course group（P<0.05,respectively）. ③There was no significant difference in the difference of DHI dimensions and total score between the short course group and the long course group before after reduction（P>0.05,respectively）. Conclusion:The duration of posterior semicircular canal BPPV（P-BPPV） does not affect the short-term efficacy of P-BPPV repositioning treatment, but patients with long course of P-BPPV are more likely to have moderate to severe residual symptoms after successful CRP，mainly in social function and emotional psychology.

A dry lunar mantle reservoir for young mare basalts of Chang'e-5.

The distribution of water in the Moon's interior carries implications for the origin of the Moon1, the crystallization of the lunar magma ocean2 and the duration of lunar volcanism2. The Chang'e-5 mission returned some of the youngest mare basalt samples reported so far, dated at 2.0 billion years ago (Ga)3, from the northwestern Procellarum KREEP Terrane, providing a probe into the spatiotemporal evolution of lunar water. Here we report the water abundances and hydrogen isotope compositions of apatite and ilmenite-hosted melt inclusions from the Chang'e-5 basalts. We derive a maximum water abundance of 283 ± 22 µg g-1 and a deuterium/hydrogen ratio of (1.06 ± 0.25) × 10-4 for the parent magma. Accounting for low-degree partial melting of the depleted mantle followed by extensive magma fractional crystallization4, we estimate a maximum mantle water abundance of 1-5 µg g-1, suggesting that the Moon's youngest volcanism was not driven by abundant water in its mantle source. Such a modest water content for the Chang'e-5 basalt mantle source region is at the low end of the range estimated from mare basalts that erupted from around 4.0 Ga to 2.8 Ga (refs. 5,6), suggesting that the mantle source of the Chang'e-5 basalts had become dehydrated by 2.0 Ga through previous melt extraction from the Procellarum KREEP Terrane mantle during prolonged volcanic activity.

Two-stage fluid pathways generated by volume expansion reactions: insights from the replacement of pyrite by chalcopyrite.

Volume expansion reactions involved in mineral-fluid interactions are linked to a number of geological processes, including silicate weathering, retrograde metamorphism, and mineralization. However, the effect of volume expansion on replacement reactions remains unclear. Here, we demonstrate that reactions associated with volume expansion during the replacement of pyrite by chalcopyrite involve two competing processes. The reaction is initially augmented because of the development of reaction-induced fractures in the pyrite. However, these fractures are subsequently filled by compacted products, which ultimately disrupts the contact and interaction between bulk fluids and the pristine pyrite surface. These competing processes indicate that replacement reactions are both augmented and inhibited by volume expansion reactions during pyrite replacement.

Application of FIB-SEM Techniques for the Advanced Characterization of Earth and Planetary Materials.

Advanced microanalytical techniques such as high-resolution transmission electron microscopy (HRTEM), atom probe tomography (APT), and synchrotron-based scanning transmission X-ray microscopy (STXM) enable one to characterize the structure and chemical and isotopic compositions of natural materials down towards the atomic scale. Dual focused ion beam-scanning electron microscopy (FIB-SEM) is a powerful tool for site-specific sample preparation and subsequent analysis by TEM, APT, and STXM to the highest energy and spatial resolutions. FIB-SEM also works as a stand-alone technique for three-dimensional (3D) tomography. In this review, we will outline the principles and challenges when using FIB-SEM for the advanced characterization of natural materials in the Earth and Planetary Sciences. More specifically, we aim to highlight the state-of-the-art applications of FIB-SEM using examples including (a) traditional FIB ultrathin sample preparation of small particles in the study of space weathering of lunar soil grains, (b) migration of Pb isotopes in zircons by FIB-based APT, (c) coordinated synchrotron-based STXM characterization of extraterrestrial organic material in carbonaceous chondrite, and finally (d) FIB-based 3D tomography of oil shale pores by slice and view methods. Dual beam FIB-SEM is a powerful analytical platform, the scope of which, for technological development and adaptation, is vast and exciting in the field of Earth and Planetary Sciences. For example, dual beam FIB-SEM will be a vital technique for the characterization of fine-grained asteroid and lunar samples returned to the Earth in the near future.

Characterizing and optimizing magnetosome production of Magnetospirillum sp. XM-1 isolated from Xi'an City Moat, China.

Pure culture of magnetotactic bacteria is desirable to understand their physiology, evolution and biomineralization. Here, we report a new strain Magnetospirillum sp. XM-1 that was recently isolated and cultivated from the eutrophic city moat of Xi'an, China. Magnetosome biomineralization, crystallographic and magnetic properties of XM-1 were characterized by using a combination of transmission electron microscopy and rock magnetic methods. Cell growth and magnetite production was optimized by response surface methodology. We found that the Magnetospirillum strain XM-1 is different from the model strain Magnetospirillum magneticum AMB-1 in terms of magnetite magnetosomes, optimal growth temperature and nutrient requirements. Sodium succinate, sodium nitrate and ferric citrate are the three most significant factors associated with the optimization of cell growth and magnetosome production for XM-1.

Institutional challenges for EIA implementation in China: a case study of development versus environmental protection.

This paper provides a complete case study analysis of environmental impact assessment (EIA) implementation in China from planning to legal challenge, which is typical but rarely reported. The analysis takes an historical perspective on the regulatory and institutional structures through which EIA has been implemented in China, in order to evaluate the extent to which EIA has matured over the last 10 years. The case study relates to a proposed recreation/tourist development at Dianshan Lake, a protected water resource for Shanghai. Legal and administrative challenge began in 1993, when the case was initiated with a letter from the public, and concluded in 1996, when the case was decided in a court judgment. More recent follow-up research indicates that many issues have continued to be problems for EIA implementation in China. Policy implications in terms of regulatory structure, institutional arrangement, EIA procedure, EIA practitioners, and public participation can be drawn, and lessons learned for both the government and the developers. The study emphasizes the problem of relying on reorientation of existing institutions to promote new (environmental) priorities.

[Clinical investigation of application of lung biopsy in the diagnosis of diffuse pulmonary interstitial disease].

OBJECTIVE: To evaluate the application of lung biopsy in the diagnosis of diffuse pulmonary interstitial disease (DPID). METHODS: The data of lung biopsy from 17 cases with uncertain DPID obtained during the period of July 1997 and December 2002 were retrospectively analysed. RESULTS: All the cases were diagnosed by pathology. Three of them were diagnosed as sarcoidosis. Two were pulmonary alveolar proteinosis. One with usual interstitial pneumonia (UIP), one with bronchiolitis obliterans and organizing pneumonia, one with nonspecific pneumonia, one with Castleman's disease, one with pulmonary lymph angio-leiomyomatosis, two with bronchioalveolar carcinoma, one as rheumatoid pulmonary fibrosis complicated with pulmonary squamous cancer and locally metastasis in lungs, two as pulmonary lymphangitic carcinomatosis, one as lung squamous cancer with pulmonary lymphangitic metastasis, and one with primary pulmonary paraganglioma. CONCLUSION: Harvest of lung tissue directly by biopsy could be the most useful diagnostic method for DPID, and it is a highly valuable diagnostic tool for those patients whose diagnosis is uncertain with routine chest film and high resolution computed tomography.