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Because of the viscous properties of rock, a viscoelastic model is closer to the real situation of rock media than an elastic model is. Cracks in the media are common geophysical phenomena. In particular, horizontal cracks are widely developed in the thin interbeds of sedimentary rock. Taking a Cole—Cole viscoelastic medium as the background medium, we compute the frequency-dependent velocities, quality factors, anisotropy coefficients, crack densities, and crack aspect ratios of P- and S-waves based on Hudson's theory. We give the velocity-stress staggered finite-difference equations of the elastic wave propagation in a cylindrical coordinate system for a viscoelastic medium with horizontal cracks and numerically simulate acoustic propagation in the cracked medium with different crack densities and aspect ratios. The simulation results indicate that as the crack density increases outside a borehole the P- and S-wave velocities decrease and their amplitudes increase, in a borehole the P- and S—wave velocities and amplitudes decrease; as the crack aspect ratios increases outside a borehole the P-wave velocities decrease, its amplitudes change little and the S-wave amplitudes and velocities change little, in a borehole the P-wave velocities and amplitudes decrease and the S-wave velocities in a borehole change little, and the S-wave amplitudes decrease. [ABSTRACT FROM AUTHOR]

The roles of angiotensin II (Ang II) AT1 (AT1a) receptors and its downstream target Na+/H+ exchanger 3 (NHE3) in the proximal tubules in the development of two-kidney, 1-clip (2K1C) Goldblatt hypertension have not been investigated previously. The present study tested the hypothesis that deletion of the AT1a receptor or NHE3 selectively in the proximal tubules of the kidney attenuates the development of 2K1C hypertension using novel mouse models with proximal tubule-specific deletion of AT1a receptors or NHE3. 2K1C Goldblatt hypertension was induced by placing a silver clip (0.12 mm) on the left renal artery for 4 weeks in adult male wild-type (WT), global Agtr1a−/−, proximal tubule (PT)-specific PT-Agtr1a−/− or PT-Nhe3−/− mice, respectively. As expected, telemetry blood pressure increased in a time-dependent manner in WT mice, reaching a maximal response by Week 3 (p < 0.01). 2K1C hypertension in WT mice was associated with increases in renin expression in the clipped kidney and decreases in the nonclipped kidney (p < 0.05). Plasma and kidney Ang II were significantly increased in WT mice with 2K1C hypertension (p < 0.05). Tubulointerstitial fibrotic responses were significantly increased in the clipped kidney (p < 0.01). Whole-body deletion of AT1a receptors completely blocked the development of 2K1C hypertension in Agtr1a−/− mice (p < 0.01 vs. WT). Likewise, proximal tubule-specific deletion of Agtr1a in PT-Agtr1a−/− mice or NHE3 in PT-Nhe3−/− mice also blocked the development of 2K1C hypertension (p < 0.01 vs. WT). Taken together, the present study provides new evidence for a critical role of proximal tubule Ang II/AT1 (AT1a)/NHE3 axis in the development of 2K1C Goldblatt hypertension. [ABSTRACT FROM AUTHOR]

In order to understand the effect of fluid-induced alteration on the Sm-Nd isotope systematic in apatite, a series of fluid/apatite reaction experiments, which involve reacting the well-characterized Durango fluorapatite with CO 2 ± CaCO 3 -, NaF- or HCl ± CaCl 2 -bearing solutions with a known 143Nd/144Nd ratio, were conducted at 800 or 600 °C at 200 MPa. In experiments involving CO 2 -H 2 O ± CaCO 3 , the fluorapatite grains did not react with the solution, such that the Sm-Nd isotopic system was undisturbed. In experiments involving NaF, the fluorapatite grains were partially to completely altered. During the alteration process, REE mobilization was retarded via the coupled substitution Na+ + REE3+ = 2Ca2+ due to the high activity of Na in the fluid. Because the REE were not mobilized, the 147Sm/144Nd ratios remained constant. However, the 143Nd/144Nd ratios were slightly altered due to small degrees of Nd isotopic exchange between the fluid and fluorapatite. In experiments involving HCl ± CaCl 2 , the fluorapatite grains were partially altered, and the REE were variably leached from the altered fluorapatite. Leaching of REE was accompanied by an increase in the 147Sm/144Nd ratio, which is related to the higher compatibility of Sm in the fluorapatite structure and the lower mobility of Sm in Cl-bearing fluids. Although the 147Sm/144Nd ratios were strongly affected, the 143Nd/144Nd ratios experienced only a small change, which is related to the slow rate of transport for Nd between reaction-front fluid and bulk fluid. In general, the experimental results indicate that fluid chemistry is the main factor controlling the response of the Sm-Nd isotopic system to fluid-induced alteration. The 147Sm/144Nd ratio of apatite can be highly modified, and in turn the Sm-Nd isotopic system is disturbed when the fluids are rich in ligands that are able to facilitate REE mobilization and fractionation. Therefore, a thorough evaluation of the fluid-rock history, along with the conjectured fluid chemistry, is necessary before using apatite Sm-Nd isotopes as geological indicators. [ABSTRACT FROM AUTHOR]

The ridged substrate integrated coaxial line (RSICL) supports transverse electromagnetic (TEM) wave with small size, broadband, and good shielding performance. This article presents a two-material RSICL, which has two different dielectric materials filled in its substrate layers. Compared with the conventional RSICL with only one dielectric material, the two-material RSICL shows a higher cutoff frequency of the first higher order mode. Hence, the monomode bandwidth of the two-material RSICL can be improved accordingly. Based on the printed circuit board (PCB) process, the two-material RSICL with feeding structures is designed and fabricated. In the experiment, the first two-order modes of the two-material RSICL are excited with two types of transitions. The measured monomode bandwidth of the two-material RSICL is from dc to 44 GHz, which is 14.9% wider than that of the one-material RSICL. [ABSTRACT FROM AUTHOR]

• The proposed polarizer enables independent, tunable phase modulation without altering the structure size. • The proposed DBS can switch the types of scattered beams through the phase-transition of VO 2. • The proposed AZM can switch the function between achromatic metalens and zoom metalens through the phase-transition of VO 2. • The proposed MFOVG can switch the function between metalens and FOAM generator through the phase-transition of VO 2. Metasurfaces, especially coded ones, have gained significant attention for their excellent ability to control electromagnetic (EM) waves, opening up possibilities for a new generation of miniaturized devices. However, integrating multiple functionalities into a single metasurface while endowing tunable performance remains a challenge. In this study, we propose a strategy to design switchable and multifunctional terahertz (THz) photonic devices using complementary Gold-VO 2 split resonant ring (GV-SRR) and complementary Gold-VO 2 split resonant oblong (GV-SRO) structures. The designed devices can convert right-handed circularly polarized (RCP) light into left-handed circularly polarized (LCP) light in three frequency bands, corresponding to center frequencies fre. 1 = 0.34 THz (narrowband), fre. 2 = 0.50 THz (narrowband), and fre. 3 = 0.80 THz (broadband). The phases of the reflected LCP wave can be independently modulated across different frequency bands by rotating the in-plane orientation of GV-SRR and GV-SRO separately. In addition, the overall phase reconstruction can be achieved through the state change of VO 2. By arranging GV-SRR and GV-SRO in a defined encoding form, the engineered photonic devices can exhibit distinct and switchable capabilities in modulating EM wavefronts across various frequency ranges. As proof-of-concept examples, we have designed three encoded photonic devices, namely, a dynamic beam splitter (DBS), an achromatic and zoom metalens (AZM), and a switchable device between metalens and focusing orbital angular momentum (OAM) generator (MFOAM). These devices have potential applications in wireless communication, AR holographic displays, and information processing. [ABSTRACT FROM AUTHOR]

The mode-selective transmission line (MSTL) has excellent transmission performance due to its wide bandwidth and low loss, which is characterized by the mode-selective effect. In this article, a skew-symmetric slotted waveguide (SSSW) is proposed, whose dominant mode also exhibits the interesting mode-selective effect and transmission performance is similar to that of the MSTL. It is investigated that the dominant mode of the SSSW performs quasi-transverse electromagnetic (TEM) mode at low frequency and quasi-TE10 mode at high frequency. Then, for fast design, a characteristic impedance formula of the SSSW is derived by the conformal mapping, which has the error less than 3% compared with the finite-element method (FEM). In addition, a microstrip line (MSL) to grounded coplanar waveguide (GCPW) transition is designed to excite the dominant mode of the SSSW, with good transmission of the dominant mode and significant suppression of higher order modes. Finally, the SSSWs with the transitions are fabricated under printed circuit board (PCB) technology and measured with the S21 larger than −2.1 dB and the S11 less than −12.7 dB from dc to 67 GHz, and the attenuation of the SSSW is less than 0.065 dB/mm below 65 GHz. Good eye diagram is obtained with bit error rate (BER) less than $10^{-12}$ for the 32-Gb/s data rate. [ABSTRACT FROM AUTHOR]

In this article, a compact unconditionally stable two-dimensional (2-D) stochastic weighted Laguerre polynomial finite-difference time-domain (S-WLP-FDTD) method for geometric uncertainty in superconducting transmission lines is proposed. It calculates both the Maxwell equations and the London equations and uses a weighted Laguerre polynomial (WLP) scheme to eliminate the stability constraint. The mean and the standard deviation of electromagnetic fields, voltages, and currents are calculated. Compared with the Monte Carlo method and 2-D S-FDTD method, the proposed method has the same accuracy but much higher efficiency. The runtime of the proposed S-WLP-FDTD method is only 2.4% of that of the S-FDTD method. Thus, the proposed method is suitable for predicting the influence of geometric uncertainty on superconducting transmission lines. [ABSTRACT FROM AUTHOR]

Apatite is a ubiquitous accessory mineral in crustal rocks. The Sr-isotope record of apatite has a wide range of applications in earth science studies. However, apatite has been documented to be easily altered by certain fluids. Currently, the impact of metasomatic alteration on Sr-isotopic abundances in apatite is not well known. In order to better understand this issue, well-characterized fluorapatite grains have been metasomatized experimentally at a temperature of 800 or 600 °C and a pressure of 200 MPa. Fluids used included a CO 2 -H 2 O mixture and NaF-, CaCl 2 -, and HCl-bearing solutions, all of which were doped with a standard solution with a known 87Sr/86Sr ratio. In the fluorapatite + CO 2 -H 2 O experiments, the fluorapatite grains were not altered by the fluids; thus, their Sr isotope compositions were generally kept unchanged. However, the other fluids induced partial to complete alteration of fluorapatite. In experiments involving the NaF- or HCl-bearing solutions, the Sr content remained constant or was increased in altered areas of the fluorapatite, and the Sr isotopes underwent changes with partial isotopic signature of the reacting solutions. In experiments involving CaCl 2 , the Sr content was decreased in the altered fluorapatite because high Ca activity in the solution caused Ca to replace Sr on the Ca site. Notably, the Sr isotopic ratios are still changed, although to a relatively small extent. The efficient Sr isotopic exchange between fluid and apatite is attributed to the rapid transport rate of Sr between the reaction-interface fluid and bulk fluid surrounding the apatite. This experimental study demonstrates that the response of apatite Sr isotopes to metasomatic alteration is mainly controlled by the chemistry of fluids. Overall, Sr isotopes become susceptible to hydrothermal alteration once the apatite is chemically reactive with the fluids. Therefore, it is important to evaluate the fluid-rock history, especially the conjectured fluid composition before using Sr isotopes from apatite as a geochemical tracer. [ABSTRACT FROM AUTHOR]

In this study, molecular dynamics (MD) simulations were used to systematically investigate the behaviour of hydrogen (H) and helium (He) around 1/2<111> screw dislocations (SDs) and 1/2<111>{110} edge dislocations (EDs) in tungsten (W). The binding energy distributions of H and He around these two dislocations were obtained by molecular statics methods. The results revealed that both types of dislocation cores strongly attracted H and He atoms, and capture strengths were stronger for EDs than SDs. The simulations predicted that two factors influenced the interaction: strain fields of dislocations (effects of dislocations on H/He atoms) and residual stresses of H/He atoms (influences of H/He atoms on dislocations), which were validated. In the selection of trapping sites, H was synergistically affected by hydrostatic compressive and shear stress fields, and He was influenced only by shear stress fields. Conversely, the insertion of H atoms reduced the local lattice distortion of the SDs and induced the EDs to glide. He atoms repelled neighbouring atoms to increase the free volume of the trapping site. The diffusion behaviour of H/He atoms around dislocation cores was studied through nudged elastic band (NEB) and MD methods. Both H and He atoms tended to diffuse along screw channels around SD lines and one-dimensional channels inclined to ED lines, preferentially migrating along the dislocation line. The results of this study provide new insight into the retention and diffusion of H and He atoms in W. However, we have not been able to determine the clear influence of dislocations on the retention amount and diffusion tendency of H or He atom. [ABSTRACT FROM AUTHOR]

In this article, an ultrawideband magnetic probe with high electric field suppression ratio (EFSR) is proposed. The probe has three parts: the loop part, the transmission part, and the head part. Shield metal sheets are designed in the loop part to enhance EFSR. The tapered transmission line in the transmission part and the quasi coaxial transition in the head part are adopted for impedance matching between the induction loop and the grounded coplanar waveguide (GCPW) in the head part. Then, segmented resistance–inductance–capacitance (RLC) equivalent circuit models of the probe are proposed for magnetic field coupling and electric field coupling, which are suitable for accurate modeling and efficient optimization of the magnetic probe. In addition, the coupling capacitors between the shield metal sheets and the device under test (DUT) are extracted utilizing the conformal transforming method with analytical formulas. Finally, this magnetic probe is fabricated under printed circuit board (PCB) technology and used in measuring the magnetic field distribution. The measurement and simulation results agree well. The probe has a bandwidth of 100 MHz–30 GHz and an EFSR of higher than 21 dB. Compared with the conventional probe with similar bandwidth, the proposed probe can improve the EFSR by 9 dB. [ABSTRACT FROM AUTHOR]

The Longbohe Fe-Cu-(LREE) deposit in the Longbohe–Sin Quyen (LSQ) Fe-Cu belt in the border zone of South China and northern Vietnam has a resource of > 1 million tonnes Cu, and was once speculated to be a potentially important subduction-related deposit of Precambrian age, but with poor constraints. Our study reveals that the major Fe-, Cu-, and LREE mineralization comprises three stages and are comparable to typical IOCG deposits worldwide. Stage I is characterized by pervasive Na alteration, followed by Fe mineralization stage (Stage II) consisting of Ti-poor magnetite associated with Ca-Na alteration forming amphibole and albite. Stage III, the Cu-LREE mineralization stage, is composed mainly of chalcopyrite and REE-rich allanite with minor pyrrhotite and pyrite. Stages I and II formed at broadly comparable temperatures of 515 to 670 ºC, and have δ18O fluid values of 4.3 to 11.7 ‰, indicating dominantly magmatic fluids. Furthermore, they have hydrothermal zircon with εHf(t) values (7.5 to 12.7) similar to coeval mafic intrusions in the region, likely indicating a mafic magma-source for the fluids. Stage III fluids have lower temperatures (332 to 402 ºC) but exhibit magmatic-like δ34S values (1.2 to 3.7 ‰) similarly suggestive of a major magmatic source. However, they have distinctly lower εHf(t) and εNd(t) values comparable to those of coeval regional felsic intrusions, suggesting that an additional component of REE-rich external fluid from felsic magmas was involved during the Cu-REE mineralization. Hydrothermal zircons from Stages II and III have similar U–Pb ages of ~ 850 Ma, providing tight constraints on the timing of Fe-Cu mineralization. The new U–Pb ages indicate that the Longbohe deposit is coeval with the Sin Quyen IOCG deposit in northern Vietnam, and with the regional subduction-related magmatism, indicating that the Longbohe–Sin Quyen belt is of Neoproterozoic age and formed in a convergent setting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four types of HREE-rich minerals are identified in the giant Bayan Obo deposit. • The identified HREE-minerals were mainly precipitated from carbonatite-relate fluids. • A local physiochemical environment that facilitated the formation of niobium oxides is significant for efficient HREE deposition. The carbonatite-related Bayan Obo deposit, China is the largest REE resource in the world. This deposit has long been a major light REE (LREE) producer, with heavy REE (HREE) rarely exploited. In order to better understand the occurrence of HREE in the deposit, this paper conducts a study of HREE-rich minerals at Bayan Obo. Overall, four types of HREE-rich minerals are identified, including fergusonite-group mineral [(Y, REE)(Nb, Ta, Ti)O 4 ], samarskite-group mineral [(Y, REE, Fe) 2 (Nb, Ta, Ti) 2 O 8 ], aeschynite-group mineral [(Y, REE, Ca, Th, U)(Nb, Ta, Ti) 2 O 6 ], and a type of unknown Pb-rich mineral. These minerals have HREE contents varying from 3.4 wt% to 46.4 wt%, mostly between 19.7 wt% and 34.3 wt%. Yttrium, Dy and Gd are the major REE constitute. Textual relations indicate that the HREE-rich minerals were mainly precipitated from carbonatite-related fluids, with small amounts of grains crystallized from the carbonatitic magma or deposited from post-ore modification fluids. The HREE-rich minerals occur in close temporal and/or spatial association with LREE minerals (e.g., monazite and bastnäsite), so formation of these HREE-minerals does not mean strong LREE-HREE fractionation during the ore-formation or post-ore modification process. Given that certain niobium oxides strongly prefer HREE relative to LREE in the mineral structure, a local physiochemical environment that allowed for the deposition of niobium oxides may be significant for efficient HREE deposition. Although HREE-rich minerals are not widely present in the deposit, they tend to occur as clusters in places. To determine what proportions of HREE can be hosted in the HREE-rich minerals, the weight proportions and REE contents of major REE-bearing minerals were measured in three representative ore samples. The results show that ∼ 25–57 % HREE can be hosted in fergusonite, samarskite, and/or aeschynite. Therefore, the newly identified HREE-rich minerals are non-negligible targets for future exploitation of HREE in the Bayan Obo deposit. [ABSTRACT FROM AUTHOR]

First-principles theory is applied to identify the structure of γ-Al 2 O 3 first. Then, hydrogen dissolution and diffusion behavior was further studied to reveal the reason that permeation reduction factor (PRF) of γ-Al 2 O 3 is lower than that of α-Al 2 O 3. Our calculations show that the formation energy for Al vacancy at the octahedral interstitial site (V Al − OIS − 3) is lower than that at the tetrahedral interstitial site (V Al − TIS − 3), and are far lower than those of other defects in both defective spinel and non-spinel γ-Al 2 O 3. Thus, the stability of V Al − OIS − 3 is higher than that of V Al − TIS − 3 in both Al-rich and O-rich environments. However, when hydrogen atoms are introduced into γ-Al 2 O 3 , the stability of [V Al-TIS -H]−2 is higher than that of [V Al-OIS -H]−2 in the defective spinel γ-Al 2 O 3 structure, while the opposite is true for the non-spinel γ-Al 2 O 3 structure. The vibrational frequencies for OH− in [V Al-TIS -H]−2 and [V Al-OIS -H]−2 for defective γ-Al 2 O 3 are calculated to be 3608 cm−1 and 3374 cm−1, respectively, which is in excellent agreement with the infrared (IR) absorption peaks observed at ∼3500 and ∼3300 cm−1. The defective spinel model is more suitable for describing the γ-Al 2 O 3 structure. In defective spinel γ-Al 2 O 3 , there are many native Al vacancies, which are arranged in a straight line along the [ 2 1 ¯ 1 ¯ 0 ] direction. The migration barrier for H diffusion along these native Al vacancies is so low that these Al vacancies can provide a rapid diffusion channel for H. Thus, the permeability of H in γ-Al 2 O 3 is much higher than that in α-Al 2 O 3 leading to a lower permeation reduction factor (PRF). Our results can provide not only a sound theoretical explanation for the low PRF of γ-Al 2 O 3 but also a direction to improve the efficiency in preventing H permeation through FeAl/Al 2 O 3 tritium permeation barriers (TPBs). [ABSTRACT FROM AUTHOR]

There remains a challenge for elegantly designing structurally simple but multi-signal fluorescence probes to visualize simultaneously various intracellular redox species and microenvironmental parameters. Herein we present such a design in the small probe COU-Mito featuring the graft of a strong electron-withdrawing 4-pyridiniumylacrylonitrile unit to an electron-donating diethylamino coumarin. The introduction of the cyano group destroys the coplanarity of the total push-pull π-conjugation system, thus the probe exhibits very weak background red fluorescence but a turn-on response to increased viscosity which restricts the rotation of the molecular rotor between the push and pull parts around a single bond. More importantly, the introduction of the cyano group together with the 4-pyridinium moiety improves significantly the electrophilicity of the carbon-carbon double bond in the probe that allows selective oxidative cleavage and nucleophilic addition on the double bond by peroxynitrite (ONOO-) and sulfur dioxide (SO 2), respectively. Hence the probe, whilst superficially simple, is in fact a multifunctional probe capable of simultaneously discriminating viscosity, ONOO- and SO 2 in a fashion of three sets of distinct signals: red for viscosity, green for ONOO-, and blue for SO 2. The probe was successfully employed to visualize the change of mitochondrial viscosity and the fluctuation of mitochondrial ONOO- and SO 2 levels in living cells and zebrafish, and to probe into their roles in the hepatotoxicity induced by acetaminophen, a widely used analgesic and antipyretic drug. [Display omitted] • Imaging of viscosity, ONOO- and SO 2 in red, green and blue channels, respectively. • Excellent sensitivity and fast response toward ONOO-. • Imaging of mitochondrial ONOO-, SO 2 and viscosity in living cells and zebrafish. • Visualizing the toxicity mechanism of acetaminophen. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal zircon is identified in the Bayan Obo REE deposit for the first time. • Dating of hydrothermal zircon yielded an age of ~1.3Ga for the Bayan Obo deposit. • Substantial LREE depletion and Th/U fractionation are two discriminative features for hydrothermal zircon. The Bayan Obo deposit in China hosts the largest REE resource in the world. However, the genesis of this deposit is still highly debated, largely due to a lack of consensus on the mineralization age. The Banyan Obo deposit has experienced intensive post-ore metamorphic and metasomatic overprints, so it is crucial to choose robust chronometers to determine the primary mineralization age. In this study, zircon is identified in the REE ore of the Bayan Obo deposit. The zircon grains are in contact with or contain inclusions of hydrothermal minerals (e.g., magnetite, biotite, monazite, allanite, apatite and ilmenorutile). They have variable Th contents (14 to 1139 ppm) and are poor in U (<0.8 ppm), consistent with the Th-rich and U-poor feature of the Bayan Obo REE ore. Moreover, they have substantially low contents of light REE (La to Nd; LREE), which may be due to zircon coprecipitation with LREE-rich monazite and allanite. The combined textural and compositional features imply a hydrothermal origin of the zircon grains. The hydrothermal zircon grains have a weighted mean 208Pb-232Th age of 1297 ± 13 Ma, which places a direct constraint on the timing of REE mineralization at Bayan Obo. Notably, substantial LREE depletion and Th/U fractionation have not been documented before for hydrothermal zircon from other environments, and thus they could be taken as discriminative features for hydrothermal zircon from carbonatite-related REE deposits. Thorium-lead dating was also conducted on monazite from the zircon-bearing sample, yielding 208Pb-232Th ages (993 to 319 Ma) variably younger than that of zircon. The younger monazite Th-Pb ages could have resulted from disturbance of the Th-Pb isotopic system during post-ore modification process. Similarly, monazite has younger Th-U-Pb dates than zircon in many other geologically-complicated carbonatites or REE deposits. Such a phenomenon implies that the zircon Th-U-Pb chronometer is robust even if the host-rocks have experienced intensive modification, whereas monazite Th-U-Pb chronometer is more susceptible to modification. Therefore, younger Th-U-Pb dates of monazite should be interpreted with caution as they may record the timing of post-ore modification event or represent partial resetting, and hence geologically meaningless results. [ABSTRACT FROM AUTHOR]

In this article, a discontinuous Galerkin time-domain (DGTD) method hybridized with Robin transmission condition (RTC-DGTD) is proposed for the transient thermal analysis of 3-D integrated circuits (ICs). As a kind of domain decomposition method (DDM), the DGTD method employs a term named numerical flux for the information exchange of solutions between neighboring subdomains. The numerical flux is a function of both temperature $T$ and heat flux q, and thus for the heat equation, apart from $T$ , the variable q has to be solved as well. To reach this, the traditional DGTD method decomposes the second-order partial-differential thermal equation into two first-order ones, which results that both $T$ and q need to be solved in the whole computational domain, thereby the computational cost is extremely expensive. In this work, to get this trouble-treated, the proposed DGTD method is directly applied to discretize the second-order heat equation. An RTC is established at the interfaces of subdomains, which serves as the second governing equation and meanwhile bridges another connection of solutions in adjacent subdomains. In this way, the new variable q is now only present at the interfaces of subdomains. Consequently, the total number of unknowns is significantly reduced compared with that in the traditional DGTD method. To further speed up the time-marching scheme, an adaptive time-stepping method in terms of the proportional–integral–derivative (PID) control algorithm is employed. Besides, by introducing a restriction operator, the globally coupled matrix equation is torn into a number of small matrix equations pertinent to each subdomain, which is later solved via a finite-element tearing and interconnecting (FETI)-like method. To validate and verify the accuracy and efficiency of the proposed algorithm, several representative examples are studied and compared with COMSOL simulations. [ABSTRACT FROM AUTHOR]

The destruction of the North China Craton (NCC) is a well‐known dynamic event in the Mesozoic, but the western NCC, with only few magmatic activities, has lacked studies so far. The Zijinshan alkaline complex, tectonically located at the western part of the NCC and the eastern edge of Ordos Block/Basin, is one of the most typical alkaline intrusions during the NCC destruction, and consists of monzonite, aegirine–augite syenite, nepheline syenite, pseudoleucite phonolite and trachyte porphyry. Geochronological, geochemical and in situ Sr–Nd–Hf isotopic analyses were performed on the various lithologies, in order to reveal the magma sources, petrogenesis and possible geodynamic processes. Zircon and titanite U–Pb dating shows that the Zijinshan complex was emplaced at ~130 Ma. The main rocks are enriched in light rare earth elements (LREEs) and large‐ion lithophile elements (LILEs; such as Rb, Ba, K, Sr), and depleted in heavy rare earth elements (HREEs) and high‐field‐strength elements (HFSEs; such as Th, U, Nb, Ta, Ti), without negative Eu anomaly. In addition, the obviously enriched and inhomogeneous Sr–Nd isotopic components occurred among the various lithologies, implying the primary magma of Zijinshan complex may originate from a deep mixed source. Specifically, the monzonites of Zijinshan complex come from the partial melting of the enriched lithospheric mantle with participation of crustal materials. Meanwhile, the nepheline syenites and alkaline volcanics originated from the enriched lithospheric mantle mixing with the depleted asthenosphere‐derived compositions. During the NCC destruction, continuous asthenospheric upwelling resulted in several times of mixing of melts from asthenospheric mantle, lithospheric mantle and lower crust in different proportions, and then the mixed magma of each episode migrated upward to the shallow part to form the Zijinshan pluton. [ABSTRACT FROM AUTHOR]

Alkaline magmatic rocks are important hosts of rare earth elements (REE) and high field-strength elements (HFSE, such as Nb and Zr) deposits. Previous studies have suggested the Nb-REE enriched alkaline rocks were derived from mantle sources metasomatized during subduction-related crustal recycling processes. However, details on how these rare metal enriched mantle reservoirs form are poorly known. In this study, we present detailed petrographic and geochemical data for the Nb-REE enriched alkali basalt and trachyte from Tianbao volcanics located in South Qinling, Central China. U Pb dating of titanite from alkali basalt and trachyte yielded identical ages of ∼430 Ma. The alkali basalt in Tianbao contains high TiO 2 , total alkali and Na 2 O/K 2 O, and relative enrichment of LREE, Th, U, Nb, Ta, Zr and Hf. Compared to the alkali basalt, the trachyte has lower Ti and P, but higher Al, Na, K, REE, Nb and Zr contents. Moreover, they have similar Sr-Nd-Pb isotope compositions with low initial 87Sr/86Sr (0.70346 to 0.70566), positive ε Nd (t) (+3.61 to +4.61), and moderate 206Pb/204Pb (17.59 to 18.61), 207Pb/204Pb (15.54 to 15.63) and 208Pb/204Pb (37.64 to 38.65). SiO 2 content shows a slightly positive correlation with (87Sr/86Sr) i and negative correlation with ε Nd (t), indicating that crustal contamination was involved in the evolution of at least the more siliceous magmas. MELTS modeling reveals that trachyte can evolve from the alkali basalt by fractional crystallization of clinopyroxene, Fe Ti oxides, feldspar, biotite and apatite with <5% contamination of local metasedimentary or felsic rocks. The batch melting modeling indicates that the alkali basalt could be formed via mixing of a low-degree (F = 5%) melt of mantle peridotite (∼82%) and a high-degree (F = 30%) melt of metasomatic hornblendite veins (∼18%). The initial Sr-Nd-Pb isotopes of these volcanics are consistent with those of global ocean island basalts, with mixed components of depleted MORB, HIMU and EMI type mantle sources. These data, together with the regional tectono-magmatic framework, are consistent with a model for magma generation from a mantle metasomatized by the Neoproterozoic subducted oceanic crust. Our genetic model highlights the importance of subduction-related slab metasomatized mantle for the generation of Nb-REE enriched alkaline magmatism and can be also applicable to other alkaline intrusions associated with or without carbonatites around the world. [Display omitted] • Trachyte evolved from the alkali basalt with minor crustal contamination. • Tianbao volcanics generated from partial melting of amphibole-bearing peridotite. • The metasomatized mantle source resulted from Neoproterozoic subduction. [ABSTRACT FROM AUTHOR]

Electrical stimulation of the right median nerve can aid coma arousal after traumatic brain injury (TBI). This study aimed to confirm the efficacy further and explore possible mechanisms of right median nerve electrical stimulation (RMNS). Five comatose patients after severe TBI from May to September 2020 in the Tianjin Medical University General Hospital received RMNS for 2 weeks besides standard management. After the 2-week treatment, the mean Glasgow Coma Scale (GCS) and neurophysiological examination were used. We then investigated the alterations in microRNA (miRNA) expression in cerebrospinal fluid (CSF) by high-throughput whole transcriptome sequencing, analyzed the data by Gene Ontology (GO) and pathway analysis, and constructed the miRNA–target gene network. Patient awareness and brain function showed a more rapid increase after treatment. We also found 38 differently expressed miRNAs, 34 of which were upregulated and 4 downregulated. GO analysis showed a relation of these differentially expressed miRNAs with neuronal growth, repair, and neural signal transmission. The most highly correlated pathways were primarily associated with the tumor necrosis factor (TNF) signaling pathway and dopaminergic synapse. The application of RMNS effectively promoted early awakening in comatose patients with severe TBI. Moreover, differentially expressed miRNAs might reduce neuronal apoptosis and increase dopamine levels by regulating target gene expression, thus participating in the specific biological process after arousal therapy. Our study provided novel targets for further research on the molecular mechanisms of RMNS arousal treatment and a new way to treat neurotraumatic diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different sources of fluids were involved in different mineralization stages at Lanniping IOCG deposit. • Fluid mixing responsible for precipitation of Cu-sulfides. • Texturally constrained apatite (e.g., OM-CL) is a good indicator of fluid evolution. Apatite occurs in diverse types of hydrothermal mineral deposits and has been widely used to constrain the nature and evolution of ore-forming fluid. The origin of ore fluids responsible for formation of iron oxide-copper–gold (IOCG) deposits remains controversial. Here we combine textural observations from optical microscopic cathodoluminescence (OM-CL) and backscattered electron (BSE) images with in situ chemical and strontium isotopic analyses of apatite in the Lanniping Fe-Cu deposit in Kangdian metallogenic province, SW China, to reconstruct the hydrothermal evolution history of this deposit. Paragenetic sequences of the deposit include pre-ore Na-alteration (stage I) of predominant albite, stage II iron-oxide mineralization with the associated Ca-Fe alteration characterized by magnetite and minor apatite, stage III Cu-Fe sulfides and the associated K-Fe alteration, and final stage IV Ca-Mg alteration. Three types of apatite at different paragenetic stages were identified in this deposit. The pristine Type 1 apatite are intergrown with stage II magnetite and show blue colors under OM-CL images. The Type 2 apatite, which are darker than Type 1 apatite under BSE images, show dark yellow CL colors. They commonly occur as metasomatized domains of Type 1 apatite and can contain chalcopyrite mineral inclusions, indicating that they are coeval products during stage III. The Type 3 apatite show bright yellow CL colors, and occur as overgrowth rims of both Type 1 and 2 apatite. The Type 1 apatite have highest REY contents (5342 to 12983 ppm) and primitive 87Sr/86Sr ratios ranging from 0.70630 to 0.71093, which overlap the associated igneous intrusions. In contrast, the Type 2 and Type 3 apatite have gradually lower REY contents (866 to 4255 ppm and 142 to 635 ppm, respectively) but higher 87Sr/86Sr ratios (0.71009 to 0.71698 and 0.71904 to 0.72602, respectively). Our data hence suggest that the ore-forming fluids were mainly magmatic-hydrothermal origin and were gradually enriched in radiogenic Sr isotope by mixing with external fluid. Our case study highlights that texturally constrained apatite could be utilized to effectively trace fluid evolution of IOCG mineralization, and by reference, other hydrothermal mineralizing systems. [ABSTRACT FROM AUTHOR]

Carbonatites are often temporally and spatially associated with alkaline silicate rocks. However, petrogenetic models of formation of alkaline‑carbonatite complex and the related rare metal element enrichment processes are still in a matter of debate. In this study, we present detailed petrographic observations and geochemical data for the Shaxiongdong complex, consisting of meta-pyroxenite, syenite, and carbonatite in the South Qinling Belt, Central China. Meta-pyroxenite crops out as a marginal face of the complex and has higher Mg, Fe, Ti, Ca and P contents relative to syenite, consistent with a cumulate of pyroxene, magnetite, ilmenite, titanite and apatite. Syenite is the main central phase of the complex and can cut the meta-pyroxenite as dykes or veins. Both meta-pyroxenite and syenite show various degrees of fenitization, in which the residual syenite looks like breccia cemented by fenite. Carbonatite locally occurs as dykes of dozens of centimeters in width within syenite and meta-pyroxenite and hosts the most Nb and REE of the complex. Nb-rich minerals, e.g., pyrochlore, crystallized coeval with aegirine and apatite in carbonatite, implying a magmatic origin. In contrast, most REE minerals are spatially associated with barite and are interstitial to calcite, implying they were mainly crystallized from residual carbonatite magmas or magmatic-hydrothermal fluids. Carbonatite samples with REE mineralization have oxygen isotopes slightly higher than those of unmineralized and Nb mineralized samples, supporting the involvement of hydrothermal fluids in REE mineralization. U Pb dating of titanite and zircon from meta-pyroxenite, syenite and the associated fenite yielded identical ages of ~440 Ma. Carbonatite, syenite, and meta-pyroxenite all have nearly identical Sr Nd isotopes ((87Sr/86Sr) i : 0.70298 to 0.70367; εNd(t):+3.6 to +4.6), suggesting that all of these rocks were derived from the same mantle source. Fractionation modeling suggests the syenites evolve from a parental alkali basalt magma by separation of cumulate pyroxenite in the complex and finally lead to the unmixing of Nb-REE enriched carbonatites. The subsequent fractionation of carbonatite melts led to Nb and REE mineralization in the Shaxiongdong carbonatite. Niobium minerals formed at early magmatic stage, while most REE minerals likely crystallized from the late magma residuals or precipitated from magmatic-hydrothermal fluids. This genetic model can be widely applicable to other alkaline‑carbonatite complexes and provides a reasonable explanation for extreme enrichment of rare metals in such rocks. [Display omitted] • The complex was fractionated from the same parental alkali basalt magma. • Incremental fractionation of alkaline magma leading to unmixing of the carbonatite. • Fractionation and unmixing processes play different roles in Nb and REE enrichment. [ABSTRACT FROM AUTHOR]

In this paper, we used the conventional method to simulate the helium irradiation on tungsten (110) surface with irradiation energy of 30 eV at temperature of 1300 K. Traditional methods involve simulating the helium incident process in the simulation We found that the first peak of the atomic density depth distribution of tungsten can well divide tungsten into the fuzz region and the bulk region. The helium in tungsten is uniformly distributed in the fuzz region and follows a lognormal distribution in the bulk region, and these distributions are stable and almost do not change with time. Based on this, we propose an acceleration method for molecular dynamics simulation of helium irradiation induced fuzz formation. The idea of this method is to directly add a certain amount of helium with uniform distribution and lognormal distribution in the fuzz and bulk regions of tungsten, respectively. Then, execute temperature equilibration to achieve a stable structure of the system, and finally repeat this process. This acceleration method can obtain similar helium depth distribution and tungsten surface morphology as conventional methods, and the growth rate of fuzz is proportional to the square root of the irradiation fluence, which is also consistent with experimental observations. The acceleration method can greatly speed up the simulation of helium irradiation by omitting the helium injection process, which makes it possible for molecular dynamics to simulate the formation of fuzz. • Developed a method to determine the boundary interface between the surface fuzz and bulk region of tungsten. • Proposed an accelerated molecular dynamics simulation method for helium irradiation-induced fuzz formation. • The accelerated method makes it possible to simulate the formation of fuzz using molecular dynamics. [Display omitted] [ABSTRACT FROM AUTHOR]

• Oxidative weathering and evaporative settings favor accumulation of Co-rich sedimentary pyrite in a sulfidic ocean. • Cobalt is released and mobilized during orogenic deformation and metamorphism. • Pyrite recrystallization causes cobalt release and minor S-Fe isotope variations. • Globally, evaporative marine sequences formed at ca. 2.2–2.0 and 0.9–0.7 Ga are the ideal target areas for Co resources, including those hosted in orogenic belts. The origin of sediment-hosted copper-cobalt deposits (SCDs) within metamorphic terranes remains contentious, particularly in regard to the timing of mineralization relative to basin evolution. Here, we link the timing of Cu-Co mineralization in the Zhongtiao Mountains district, central China, to basin closure during development of the Trans-North China Orogen. Metamorphic apatite from meta-evaporite has a U-Pb age (1844 ± 25 Ma) within error of a Re-Os age for molybdenite from Cu- and Co-bearing veins (1819 ± 10 Ma), implying that mineralization and metamorphism were coincident. In situ trace element and Fe-S isotope analyses of deformed sedimentary pyrite (Py I) and younger euhedral metamorphic pyrite (Py II) in pyritic graphite schist indicate that Co was mobilized from Py I via fluid-mediated dissolution and reprecipitation. In the graphite schist, representing a sulfidic shale metamorphosed at upper greenschist facies conditions, relic Py I has high δ34S values (22.9 ± 0.4‰, n = 10) and δ56Fe values (0.90 ± 0.16‰, n = 8). These values are consistent with bacterial sulfate reduction and pyrite formation in a Paleoproterozoic sulfidic sea (i.e., after the first great oxygenation event). In addition, Py I has unusually high Co contents (0.8–3.0 wt.%), suggesting that transition metals, including Co and Ni, were originally concentrated in sedimentary pyrite in an evaporative setting. The evaporitic setting is supported by the presence of sylvite in sulfidic schists and adjacent scapolitic calc-silicates. Younger Co-poor Py II has slightly lower δ34S values (21.4 ± 0.2‰, n = 19) and higher δ56Fe values (1.61 ± 0.15‰, n = 9), supporting the hypothesis that Co was released from sedimentary sulfide during dissolution and reprecipitation. The great variability of δ34S (14.8 to 22.9‰) and δ56Fe (0.13 to 2.30‰) in hydrothermal pyrite (Py III) associated with Cu-Co mineralization suggests that an external Cu-rich oxidizing fluid was involved in the ore-forming process. Copper and Co in this type of deposit are typically both considered to be derived from fertile basement rocks. This study, however, highlights another potential source for the Co, with its enrichment in a sulfidic sea along an evaporative margin and its upgrading through mobilization during orogenesis that leads to formation of a relatively high-temperature group of SCDs. Tectonometamorphic processes causing such Co enrichments took place during the Paleoproterozoic and Neoproterozoic oxygenation events, implying that the most prospective targets for Co resources are concentrated in ca. 2.2–2.0 Ga and 0.9–0.7 Ga deformed passive margin marine sequences. [ABSTRACT FROM AUTHOR]

In this study, we investigated the diffusion and incidence of helium on tungsten surfaces using first principles and molecular dynamics methods. For three common tungsten surfaces (100, 111, 110), we found that the diffusion barrier of helium is positively/negatively correlated with the interatomic spacing/surface atomic density. The diffusion barriers of helium are relatively similar on the three surfaces, ranging from 5.82 to 6.50 eV. The diffusion barrier of helium on the tungsten surface represents the lower limit of the incidence barrier for helium implantation into tungsten. In our simulation, only helium with an incidence energy greater than 7 eV has the potential to be implanted into tungsten. Generally speaking, the implantation ratio of helium increases with increasing incidence energy and decreases with increasing substrate temperature (although the effect is minor). At a constant temperature, the implantation ratio of helium exhibits an exponential relationship with the incidence energy. The depth distribution of helium can be well described by Gamma distribution function, and the shape and scale parameters of the gamma distribution function can be determined based on the mean and variance of the helium depth distribution. The proposed fitting function allows for the quantitative description of the mean and variance of the helium depth distribution based on the incidence conditions (incident energy E and substrate temperature T), thereby determining the helium depth distribution. This has important implications for the in-depth study of helium-induced tungsten surface fuzz formation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Established a newest database of REE projects with detailed information and source. • Overview the current situation of global REE projects with some critical perspectives. • Outline some newly designed supply chains outside of China. • List some valuable REE deposits that deserve more attention. Rare earth elements (REE) are key enablers for the ongoing energy and environmental transition as they are critical raw materials in many low-carbon technologies. In the past few years, many new REE projects have been developed worldwide to replenish the market, and thus are changing the supply chains. Meanwhile, comprehensive data are lacking regarding these projects, impeding investors and policymakers from having a clear view of the global supply of REE. This study establishes a new database of REE projects, along with detailed information sources. Based on these data, we present the current situation and give some critical perspectives on the future. It is shown that there are at least total 146 advanced and mining projects, involving over 303.4 million tons of rare earth oxides around the world and some newly designed supply chains. Among those projects, carbonatite type deposits are currently the main sources and most likely will dominant future targets for exploration and mining. Asia remains the largest source of REE, but Greenland, Africa, and Europe show important resource potentials if environmental issues and processing technologies are well addressed. Finally, we review rare earth projects in terms of estimated value and heavy rare earth elements resources amounts, and further list some REE deposits that deserve more attention based on this new database. [ABSTRACT FROM AUTHOR]

The steel production industry faces tremendous pressure from carbon emission peaks and carbon neutrality targets. CO 2 capture, geological utilization, and storage (CCUS) is crucial for CO 2 mitigation in fossil-fuel-based industries at scale. Here, an integrated techno-economic assessment model is built to assess the potential of CCUS retrofitting in the crude steel industry. According to this assessment, the total CO 2 emissions from 277 crude steel manufacturers represent about 1.76 billion tons. This systematic evaluation provides preliminary answers to critical questions, such as the factory inventory suitable for CCUS retrofitting, matched geological sites, CO 2 mitigation magnitude, and related cost characteristics. Furthermore, the contribution of CCUS to the carbon neutralization of the crude steel industry is predicted. With a 60% and 85% net mitigation rate, more than 53% and 82% of CO 2 emissions (942 Mt and 1466 Mt/a) in the crude steel plants can be mitigated with levelized costs of less than 60 USD/t. Suitable plants are mainly distributed in regions in or near the Bohai Bay, Junggar, Jianghan, and Ordos basins. The mitigation potential model predicts that the contribution of CCUS will be in the range of 17.6%–56.5% depending on carbon price or supporting policy, and the cumulative cost will be in the range of 189–633 billion USD. The stochastic analysis shows that the fraction of cumulative CO 2 mitigation follows the normal distribution of N (39%, 3.2%), and the related incremental cost follows N (305, 39) billion USD. CCUS could greatly help green transition and the sustainable development of the Chinese steel industry. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The H9 member of the Bayan Obo Group has metamorphic volcanic and alkaline rocks. • The ore-bearing dolomite H8 has a magmatic origin derived from the H9 formation age of ∼1.4 Ga. • Fluid trapping effect and material contribution of H9 member are prerequisites for REEs mineralization of the Bayan Obo deposit. The Bayan Obo deposit hosted in a set of metamorphic sedimentary strata contains the world's largest rare earth reserve. However, the genesis of its ore-bearing dolomites remains controversial. The temporal and spatial relationships and compositions of the surrounding strata could provide indirect genetic indications for ore-bearing dolomites, particularly the overlying H9 member. Our data suggest that the compositions of H9 member are complex, consisting of quartz sandstone, biotite shist, metamorphic volcanic rocks and alkaline rocks. The origin and genesis of different lithologies in the H9 member are different. Based on the age distribution of detrital zircons, the basement rocks from the Bayan Obo region are presumed to be the material sources for the quartz sandstone in the H9 member. The biotite schist is the alteration products of wall rocks reacting with the fluids extracted from the ore-bearing dolomite. Metamorphic volcanic rocks and alkaline rocks are also distinguished in the H9 member. Th-Pb dating of zircons from the H9 volcanic rocks indicates its formation age is around 1.4 Ga, which is earlier than the mineralization age of the ore body, and the H9 member is also affected by the Caledonian tectonic compression recorded by the age of 427 Ma. According to the temporal and spatial distribution of H9 member and ore-bearing dolomites, the dolomites are considered to be magmatic origin. H9 member acts as the caprocks of the ore-bearing dolomite, and the contribution of its material composition and entrapment play an important role in the formation of the Bayan Obo deposit. [ABSTRACT FROM AUTHOR]

The influence of the transmutation element rhenium (Re) content with 3 and 25 wt.% on deuterium (D) permeation in tungsten (W) was investigated. It was found that the addition of Re increased D diffusion coefficient and decreased D permeability, and the D diffusion coefficient of W-3%Re was approximate to that of W-25%Re while the D permeability declined with the increase of Re content. The D retention behavior in the W-Re alloys have been studied after D plasmas exposure employing the Material and Plasma Evaluation System (MAPES) in Experimental Advanced Superconducting Tokamak (EAST). As for the higher D solution energy in W-Re alloys, the total D inventory in W was significantly decreased by Re addition. [ABSTRACT FROM AUTHOR]

Pebbles made of lithium-containing ceramics with a few millimeters in diameter have been regarded as the main candidates for the tritium breeding materials. In this work, X-ray computed tomography (X-ray CT) technique has been employed to observe the microstructure of tritium breeding pebbles. The 3D pore network of the pebbles was presented and compared with normal 2D images. Based on the CT results, simulations of the heat transfer in one single pebble have been performed employing lattice Boltzmann method and showed that the gas atmospheres and microstructure have apparent influences on the thermal conductivities of pebbles. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Bayan Obo deposit has notable differences with skarn/BIF in mineralogy and magnetite geochemistry. • Trace element contents in Bayan Obo magnetite controlled by coexisting mineral, f O 2 and T. • Bayan Obo iron deposit was a hydrothermal deposit related to igneous carbonatite. The giant Bayan Obo REE deposit bears a large amount of iron resources as well. However, the genesis of iron mineralization is still highly controversial with limited research. In this study, new data of trace elements of magnetite from Bayan Obo ores, Eastern contact zone skarn and Heinaobao BIF are obtained by Laser ablation (LA) ICP-MS analyses, revealing the genesis of Bayan Obo iron resources through comparing study. The Bayan Obo deposit contains disseminated, banded and massive ores, and in which magnetite is associated with REE minerals, fluorite, aegirine, riebeckite, and biotite. Euhedral magnetite in the skarn of Eastern contact zone is usually associated with pyrite, biotite, fluorite, and bastnaesite. There are two types of magnetite in the Heinaobao BIF: (1) euhedral to subhedral magnetite associated with quartz and a small amount of amphibole; (2) anhedral magnetite associated with quartz, garnet, plagioclase, amphibole and biotite. Magnetite in the Bayan Obo is enriched in Ni, but depleted in Mg, Al, Ti, Ge, Mn, Ga and Zn, showing low and variable concentrations, which is similar to the hydrothermal magnetite. The contents of some trace elements (e.g. Ti, Mn, Sc, Zn, Nb and REE) of magnetite from the skarn ores are generally higher, indicating a relatively high formation temperature. Magnetite in the Heinaobao BIF is generally characterized by low and uniform trace element contents, except for the abnormal values of Ti, Al, Cr and Mn, suggesting the involvement of terrigenous clastic materials. Compared with Bayan Obo magnetite, the skarn magnetite has the highest Sn/Ga, Co/Ni, Nb/Ta, La/Yb, Ti/V and Ti/Al ratios, while magnetite in the BIF has the highest Al/Co and lowest Nb/Ta ratios. The significant difference in mineralogical and trace element characteristics among the three types of magnetite indicates that the iron resources in Bayan Obo deposit are unlikely to be a skarn Fe deposit nor a BIF deposit. However, the Bayan Obo magnetite shows similar geochemical characteristics to hydrothermal magnetite related to carbonatite, both of which are depleted in high field strength elements, such as Zr, Hf and Ta, and show strong positive anomalies of Mn and Zn and negative anomalies of Co and Ga. In addition, in the diagrams of Ti vs. Nb + Ta and Ti vs. Zr + Hf, the Bayan Obo magnetite falls into the field of hydrothermal magnetite associated with carbonatite. In conclusion, it is recommended that the Bayan Obo iron deposit is a typical hydrothermal deposit related to carbonatite. In this contribution, the skarn magnetite formed at high temperature and the BIF magnetite was contaminated by terrigenous materials deviating from the expected region in discriminant diagrams. It is therefore proposed that the validity of these diagrams depends on a full understanding of mineralogical characteristics of samples and magnetite precipitation environment, and that multiple discrimination diagrams should be used in combination. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mineralizing process of carbonatite system can be divided into six stages. • The associated behaviors of REE and Nb are different in migration and deposition. • The sequence of REE minerals is phosphate, fluorcarbonate, Ba-fluorocarbonate. • The main body of the deposit was formed in the autometasomatism of carbonatite. The Bayan Obo REE-Nb-Fe deposit with giant rare earth reserves, still has no unified understanding of the REE and Nb-bearing mineral evolution and the division of mineralization stages, due to the complicated metallogenic process and the huge controversy on the important issues such as the origin of ore-hosting dolomite. In this work, the whole process of carbonatite magma solidification and mineralization is divided into six stages: coarse dolomitic facies, fine dolomitic facies, disseminated mineralization, banded mineralization, massive mineralization and vein mineralization. The mineralogical composition and paragenesis of various types of rocks and ores have been systematically studied using the automatic mineral analysis technology-Advanced Mineral Identification and Characterization System (AMICS), supplemented by optical microscopy and cathodoluminescence. In order to establish the internal relationship between different stages, trace elements of six kinds of rocks and ores were analyzed. The mineralogical studies show that the rare earth minerals appear in the order of transition from the phosphate minerals in the brine-melt stage (fine dolomitic facies), through the fluorcarbonate minerals in the hydrothermal stage (disseminated, banded and massive mineralization), to the Ba-fluorcarbonate minerals in the Paleozoic vein mineralization, and all of these are generally associated with apatite, baryte, fluorite, aegirine and quartz. The distribution of niobium minerals in all kinds of ores is in the form of disseminated grains, and there is no obvious paragenetic relationship with other minerals, which indicate that niobium mineralization may only be related to the content of niobium in hydrothermal solution. The geochemical data show that all types of rocks and ores have positive anomalies of Ba and Nb, negative anomalies of U, Ta, Sr, Zr and Y. From coarse dolomitic facies to massive mineralization, the content of REE, Nb and Th increases, the content of Sr decreases, and the ratio of (La/Yb) N and (La/Nd) N increases, all of which change continuously. Vein mineralization has similar (La/Nd) N and (La + Ce + Pr) N /REE ratios compared with coarse dolomitic facies and has a wide range of Sr, Th, Nb and REE compositions, and elemental ratio and content of vein mineralization are within the distribution range of ore-hosting dolomite and different types of mineralization. Based on the above, it is considered that the main mineralization body at Bayan Obo was formed in the process of auto-metasomatism of Mesoproterozoic igneous carbonatite, while vein mineralization was the product of homogenization and re-precipitation of early ore-forming material by the Paleozoic fluids, without the addition of exogenous metallogenic materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluid immiscibility referred by CO 2 -rich and halite-bearing inclusions in arrays. • The cooling and decompression during exhumation triggered fluid immiscibility. • Saline ore fluids are derived from dehydration of evaporative carbonate rocks. • Metamorphic brines drive Cu mineralization in the metasediments. Epigenetic hydrothermal Cu-(Co) deposits are widely distributed in the Zhongtiao Mountains within the Paleoproterozoic Trans-North China Orogen in the North China Craton. Here we investigate the Henglingguan Cu deposit hosted in metasediments to gain insights on the fluid evolution characteristics associated with the ore formation. This Cu deposit is characterized by early disseminated mineralization and late quartz-vein type mineralization. The negative sulfur isotope values (about −10‰) of the vein sulfides suggests a sedimentary rock source for sulfur associated with the hydrothermal Cu mineralization. The coexistence of CO 2 -rich carbonic inclusions and halite-bearing inclusions within a single fluid inclusion assemblage suggests fluid immiscibility in the H 2 O-NaCl-CO 2 system. Based on the fluid phase analysis, our data show that the parent ore fluid was characterized by X(NaCl) of 10 to 20 mol.% (salinity of around 23 to 41 wt% NaCl) and X(CO 2) of 10 to 15 mol.% before fluid immiscibility. The estimated temperature–pressure conditions of 320 to 340 °C and 3.5 to 4.0 kbar based on the carbonic fluid inclusions is suggested to be close to the conditions of fluid immiscibility. In-situ composition analyses of fluid inclusions by LA-ICP-MS show that the ore fluids contained Na, Ca, Fe and Mn, and evolved towards Sr-Ba enrichment. The data are consistent with a metamorphic brine derived from the sedimentary rocks. The brine-rich metamorphic fluids were likely derived from the dehydration and decarbonation of evaporitic carbonate rocks developed on the basin margin or a passive continental margin. The decompression during post-collisional exhumation triggered fluid immiscibility resulting in the quartz vein-type Cu mineralization. [ABSTRACT FROM AUTHOR]

• Tritium transport code about tritium simulation for the external fuel circulating system of CFETR has been developed. • The WCCB blanket and its external loops are integrated based on COMSOL and MATLAB. • Tritium transport analysis for the external fuel circulating system and sensitivity analysis have been conducted. Water cooled ceramic breeder (WCCB) blanket was proposed as one of the candidate blanket schemes of the Chinese Fusion Engineering Test Reactor (CFETR). In this paper, a code simulating tritium transport in WCCB blanket and its external loops has been developed, where zero and two dimensional models are integrated to get more reliable results. The purge gas flow in the breeder zone, heat transfer in the blanket and tritium isotopes mass transport are considered. The isotope exchange in the purge gas and coolant loop are also taken into account in the model. The two dimensional model of the WCCB blanket and zero dimensional model of external loops are integrated to calculate tritium related quantities. The amount of tritium inventory in different components, tritium losses, tritium extracted by the tritium extraction system (TES) and purified by the coolant purification system (CPS) are obtained. The sensitivity analysis about key parameters has also been conducted. [ABSTRACT FROM AUTHOR]