Fractional crystallization causes the iron isotope contrast between mid-ocean ridge basalts and abyssal peridotites

The iron isotope contrast between mid-ocean ridge basalts and abyssal peridotites is far greater than can be explained by mantle melting alone. Here we investigate a suite of mid-ocean ridge magma chamber rocks sampled by the Ocean Drilling Project Hole 735B in the Atlantis Bank of the Indian Ocean. We report major and trace element geochemistry from these rocks and measure their iron isotope compositions to investigate the potential role of fractional crystallization during melt evolution. We observe a large range of δ56Fe that defines a significant inverse curvilinear correlation with bulk rock MgO/FeOT. These data confirm that δ56Fe in the melt increases as fractional crystallization proceeds but, contrary to expectation, δ56Fe continues to increase even when oxides begin to crystallize. We conclude that iron isotope fractionation through fractional crystallization during the evolution of mid-ocean ridge basalts from abyssal peridotites reconciles the disparity in isotopic compositions between these two lithologies

Low-degree melt metasomatic origin of heavy Fe isotope enrichment in the MORB mantle

Studies of mid-ocean ridge basalts (MORB) show a variable Fe isotope composition of the oceanic upper mantle. To test a recent hypothesis that heavy Fe isotope enrichment in the MORB mantle results from the same process of incompatible element enrichment, we conduct an Fe isotope study of well-characterized MORB samples from a magmatically robust segment (OH-1) of the Mid-Atlantic Ridge (MAR) at ∼ 35°N. The data show large Fe isotope variation (Fe = +0.03 to +0.18‰) that correlates well with the abundances and ratios of more-to-less incompatible elements and with Sr-Nd-Hf isotopes. Our findings in support of the hypothesis can be detailed as follows: (1) the oceanic upper mantle has a heterogeneous Fe isotope composition on varying small spatial scales with isotopically heavy Fe (high-Fe) preferentially associated with pyroxenite lithologies; (2) such lithologies, which are also enriched in the progressively more incompatible elements, are of low-degree (low-F) melt metasomatic origin; (3) with all the conceivable processes considered, the low-F melt metasomatism takes place at the lithosphere-asthenosphere boundary (LAB) beneath ocean basins through crystallization of incipient (Low-F) melt in the seismic low velocity zone (LVZ) at the base of the growing oceanic lithosphere (i.e., LAB) over the Earth's history since the onset of plate tectonics, forming composite lithologies with geochemically enriched pyroxenite veins dispersed in the depleted peridotite matrix; (4) such mantle of composite lithology when transported to beneath the present-day ocean ridges will undergo decompression melting and produce MORB melts with geochemical trends of “melting-induced mixing” as observed at the MAR and global MORB; (5) we predict all this to be a globally common process and widespread

Iron isotope fractionation during skarn Cu-Fe mineralization

Fe isotopes have been applied to the petrogenesis of ore deposits. However, the behavior of iron isotopes in the mineralization of porphyry-skarn deposits is still poorly understood. In this study, we report the Fe isotopes of ore mineral separations (magnetite, pyrite, chalcopyrite and pyrrhotite ) from two different skarn deposits, i.e., the Tonglvshan Cu-Fe skarn deposit developed in an oxidized hydrothermal system and the Anqing Cu skarn deposit developed in a reduced hydro-thermal system. In both deposits, the Fe isotopes of calculated equilibrium fluids are lighter than those of the intrusions responsible for the skarn and porphyry mineralization, corroborating the “light-Fe fluid” hypothesis. Interestingly, chalcopyrite in the oxidized-Tonglvshan skarn deposit has lighter Fe than chalcopyrite in the reduced-Anqing skarn deposit, which is best understood as the result of the prior precipitation of magnetite (heavy Fe) from the ore fluid in the oxidized-Tonglvshan systems and the prior precipitation of pyrrhotite (light Fe) from the ore fluid in the reduced-Anqing system. The δ 56Fe for pyrite shows an inverse correlation with δ 56Fe of magnetite in the Tonglvshan. In both deposits, the Fe isotope fractionation between chalcopyrite and pyrite is offset from equilibrium line at 350℃ and lies between the FeS-chalcopyrite equilibrium line and pyrite-chalcopyrite equilibrium line at 350℃. These observations are consistent with the FeS pathway towards pyrite formation. That is, Fe isotopes fractionation during pyrite formation depends on a path, from the initial FeS-fluid equilibrium towards the pyrite-fluid equilibrium due to the increasing extent of Fe isotopic exchange with fluids. This finding, together with the data from other deposits, allows us to propose that the pathway effect of pyrite formation in the Porphyry-skarn deposit mineralization is the dominant mechanism that controls Fe isotope characteristics

Characterization and cytotoxicity of PAHs in PM2.5 emitted from residential solid fuel burning in the Guanzhong Plain, China

The emission factors (EFs) of polycyclic aromatic hydrocarbons (PAHs) in PM2.5 were measured from commonly used stoves and fuels in the rural Guanzhong Plain, China. The toxicity of the PM2.5 also was measured using in vitro cellular tests. EFs of PAHs varied from 0.18 mg kg(-1) (maize straw charcoal burning in a clean stove) to 83.3 mg kg(-1) (maize straw burning in Heated Kang). The two largest influencing factors on PAH EFs were air supply and volatile matter proportion in fuel. Improvements in these two factors could decrease not only EFs of PAHs but also the proportion of 3-ring to 5-ring PAHs. Exposure to PM2.5 extracts caused a concentration-dependent decline in cell viability but an increase in reactive oxygen species (ROS), tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6). PM2.5 emitted from maize burning in Heated Kang showed the highest cytotoxicity, and EFs of ROS and inflammatory factors were the highest as well. In comparison, maize straw charcoal burning in a clean stove showed the lowest cytotoxicity, which indicated a clean stove and fuel treatment were both efficient methods for reducing cytotoxicity of primary PM2.5. The production of these bioreactive factors were highly correlated with 3-ring and 4-ring PAHs. Specifically, pyrene, anthracene and benzo(a)anthracene had the highest correlations with ROS production (R = 0.85, 0.81 and 0.80, respectively). This study shows that all tested stoves emitted PM2.5 that was cytotoxic to human cells; thus, there may be no safe levels of exposure to PM2,5 emissions from cooking and heating stoves using solid fuels. The study may also provide a new approach for evaluating the cytotoxicity of primary emitted PM2.5 from solid fuel burning as well as other PM2.5 sources. (C) 2018 Elsevier Ltd. All rights reserved

Optical source profiles of brown carbon in size-resolved particulate matter from typical domestic biofuel burning over Guanzhong Plain, China

In this study, both PM2.5 and size-resolved source samples were collected from a "heated kang" and an advanced stove to investigate the optical properties of brown carbon (BrC). The light-absorption coefficient (babs), the absorption Angstrom exponent (AAE), and the mass absorption cross-section (MAC) of both water and methanol-extracted BrC were investigated. The methanol-extracted BrC (BrCmethanol) had higher light absorption than water-extracted BrC (BrCwater). The value of PM2.5 babs of BrCmethanol at 365 nm(b(abs365),methanol) dramatically decreased from 64,669.8Mm(-1) for straw burning in the "heated kang" to 1169.2 Mm(-1) formaize straw briquettes burning in the advanced stove at the same burning rate. The value of PM2.5 MAC for BrCmethanol at 365 nm (MAC(365), methanol) decreased from 1.8 m(2) g(-1) in the "heated kang" to 1.3 m(2) g-1 in the advanced stove. For smoldering burning in the "heated kang", babs365, methanol, MAC365, methanol, and K+ showed a unimodal distribution that peaked at sizes < 0.4 mu m. However, the babs365, methanol and MAC(365), methanol size distributions of the briquette burning in the advanced stove showed a bimodal pattern, with a large peak at sizes < 0.4 mu m and a minor peak in the size range of 4.7-5.8 mu m. The babs365, methanol value for sizes < 0.4 mu m (277.4 Mm(-1)) was only 12.3% compared to those obtained from the "heated kang". The burning rate did not influence the size distribution pattern of either the "heated kang" or the advanced stove. Results from a radiative model show that biomass burning is an important factor for light absorptivity, and the use of an advanced stove can reduce the simple forcing efficiency value by nearly 20% in UV bands compared to the "heated kang". Our results indicate that changing the combustion style from maize straw smoldering to briquette burning in an advanced stove can effectively reduce BrC emissions during heating seasons in rural areas of Guanzhong Plain. (C) 2017 Elsevier B.V. All rights reserved

Pengembangan Modul Berbasis Bounded Inquiry Laboratory (Lab) Untuk Meningkatkan Literasi Sains Dimensi Proses Pada Materi Sistem Pencernaan Kelas XI

Penelitian bertujuan untuk: 1) Mengetahui karakteristik modul berbasis bounded inquiry laboratory (lab) untuk meningkatkan literasi sains dimensi proses; 2) Menguji kelayakan modul berbasis bounded inquiry laboratory (lab) untuk meningkatkan literasi sains dimensi proses; 3) Menguji keefektivan penggunaan modul berbasis bounded inquiry laboratory (lab) untuk meningkatkan literasi sains dimensi proses pada materi Sistem Pencernaan kelas XI. Penelitian ini menggunakan metode Research and Development (R & D) mengacu pada model Borg and Gall (1983) yang dimodifikasi. Instrumen yang digunakan adalah lembar analisis, lembar observasi, angket, lembar validasi, wawancara, dan tes. Data penelitian dianalisis dengan metode deskriptif kualitatif dan literasi sains dimensi proses dianalisis dengan N-gain ternormalisasi untuk mengetahui keefektivan modul berbasis bounded inquiry laboratory (lab), dan uji Wilcoxon untuk mengetahui literasi sains dimensi proses. Hasil penelitian dan pengembangan menunjukkan bahwa: 1) Modul berbasis bounded inquiry laboratory (lab) untuk meningkatkan literasi sains dimensi proses pada materi Sistem Pencernaan dikembangkan sesuai dengan tahapan bounded inquiry laboratory (lab) (observasi, manipulasi, generalisasi, verifikasi, aplikasi) dan pendekatan saintifik; 2) Hasil pengembangan modul berbasis bounded inquiry laboratory (lab) layak untuk diterapkan pada materi Sistem Pencernaan. Kelayakan modul berbasis bounded inquiry laboratory (lab) pada materi Sistem Pencernaan berdasarkan validasi ahli memperoleh kategori “sangat baik” dengan persentase 98,21%, validasi praktisi memperoleh kategori “sangat baik” dengan persentase 99,22%, dan responden uji coba skala kecil memperoleh kategori “baik” dengan persentase 77,34%, sehingga layak digunakan kelas XI; 3) Modul berbasis bounded inquiry laboratory (lab) pada materi Sistem Pencernaan efektif untuk meningkatkan literasi sains dimensi proses yang ditunjukkan dengan hasil uji Wilcoxon yaitu diperoleh probabilitas (p) sebesar 0,000 (p < 0,05), H0 ditolak, sehingga ada perbedaan literasi sains dimensi proses sebelum dan setelah menggunakan modul bounded inquiry laboratory (lab) pada materi sistem pencernaan. Berdasarkan hasil penelitian dapat disimpulkan bahwa karakteristik modul berbasis bounded inquiry laboratory (lab) sesuai tahapan bounded inquiry laboratory (lab) (observasi, manipulasi, generalisasi, verifikasi, aplikasi) dan pendekatan saintifik; layak dan efektif untuk meningkatkan literasi sains dimensi proses pada materi Sistem Pencernaan kelas XI

Job satisfaction and its related factors among emergency department physicians in China

BackgroundJob satisfaction is recognized as an important factor affecting the performance and quality of medical services of emergency department physicians. However, little is known about the status of job satisfaction among emergency department physicians in China. This study aimed to explore the current level of job satisfaction and its associated factors among emergency department physicians in China.MethodsA nationwide cross-sectional survey was conducted in China from July to August 2018. A total of 10,457 emergency department physicians completed the questionnaire. The structured online questionnaire collected information on socio-demographic characteristics, work-related factors, work-family conflict, and job satisfaction. Student's t-test or ANOVA were used to compare the job satisfaction scores in different characters. The generalized linear model was used to investigate the related factors of job satisfaction among emergency department physicians.ResultsThe respondents' job satisfaction average score was 12.2 ± 3.6, of which 42.01% were satisfied of which the job. The results showed that emergency department physicians over 41 years old, with a higher income and working in central and western regions were positively associated with job satisfaction. In contrast, bachelor degree and above, fixed posts, long years of service, a high frequency of night shift, perceived shortage of physicians, perceived medical errors, and higher work-family conflict scores were negatively correlated with job satisfaction among emergency department physicians.ConclusionJob satisfaction of emergency department physicians in China is low. It is suggested that hospital administrators could improve the job satisfaction of emergency department physicians by establishing an acceptable shift system, ensuring adequate emergency department staffing, increasing their income appropriately and alleviating work-family conflict

Unveiling the spatial-temporal variation of urban land use efficiency of Yangtze River Economic Belt in China under carbon emission constraints

Under the constraint of carbon emission, measuring and analyzing the spatial-temporal evolution characteristics of urban land use efficiency in the Yangtze River Economic Belt is the inherent requirement of its ecological protection and sustainable development. In this paper, we calculated the urban land use efficiency of 107 cities in the Yangtze River Economic Belt from 2006 to 2020 by using the SBM-Undesirable model with unexpected output, and analyzed its temporal evolution trend and spatial correlation relationship by using kernel density and spatial autocorrelation method. The results showed that: except in 2020, the urban land use efficiency was generally low due to the COVID-19 epidemic, and the urban land use efficiency in other years was mostly concentrated in the middle levels, and showed a trend of slow fluctuation and rise year by year. The difference of urban land use efficiency level between regions increased, and the dispersion degree in upstream, midstream and downstream increased with each passing year. Urban land use efficiency spatial imbalance was significant, and the urban land use efficiency level of large and medium-sized cities was generally lower than that of cities with low economic development level. The spatial correlation was weak, and the global spatial autocorrelation was basically insignificant, while the local spatial agglomeration areas were mainly distributed in the upstream and downstream regions, with a small distribution range and weak spatial interaction. The distribution areas of the standard deviation ellipse were gradually flattened, and the center of gravity as a whole shift significantly to the southwest. The research results are helpful to understand the development history and future trend of urban land use efficiency in various regions, and propose that cities should consider the impact of public crisis events in advance, reasonably control the scale of land expansion, and lead coordinated development and other reasonable suggestions when formulating land use policies

Single-cell RNA sequencing reveals in vivo osteoimmunology interactions between the immune and skeletal systems

BackgroundWhile osteoimmunology interactions between the immune and skeletal systems are known to play an important role in osteoblast development, differentiation and bone metabolism related disease like osteoporosis, such interactions in either bone microenvironment or peripheral circulation in vivo at the single-cell resolution have not yet been characterized.MethodsWe explored the osteoimmunology communications between immune cells and osteoblastic lineage cells (OBCs) by performing CellphoneDB and CellChat analyses with single-cell RNA sequencing (scRNA-seq) data from human femoral head. We also explored the osteoimmunology effects of immune cells in peripheral circulation on skeletal phenotypes. We used a scRNA-seq dataset of peripheral blood monocytes (PBMs) to perform deconvolution analysis. Then weighted gene co-expression network analysis (WGCNA) was used to identify monocyte subtype-specific subnetworks. We next used cell-specific network (CSN) and the least absolute shrinkage and selection operator (LASSO) to analyze the correlation of a gene subnetwork identified by WGCNA with bone mineral density (BMD).ResultsWe constructed immune cell and OBC communication networks and further identified L-R genes, such as JAG1 and NOTCH1/2, with ossification related functions. We also found a Mono4 related subnetwork that may relate to BMD variation in both older males and postmenopausal female subjects.ConclusionsThis is the first study to identify numerous ligand-receptor pairs that likely mediate signals between immune cells and osteoblastic lineage cells. This establishes a foundation to reveal advanced and in-depth osteoimmunology interactions to better understand the relationship between local bone microenvironment and immune cells in peripheral blood and the impact on bone phenotypes