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Whether or not oceanic crust basalts are affected by plate subduction is a hot topic of debate. The South China Sea is one of the largest marginal basins in the western Pacific Ocean and has been surrounded by subduction of the Pacific plate and Indian plate, yet, to date, no study has clearly shown evidence of subduction in the geochemistry of volcanism in the basin due to a lack of sampling of igneous crust basalts on the seafloor. The International Ocean Discovery Program Expedition 349 cored seafloor basalts near the fossil spreading ridges of the eastern (Site U1431) and southwestern (Site U1433 and U1434) subbasins in the South China Sea. The recovered basalt samples indicated a pyroxenite-bearing peridotite mantle source. Here, we report Mg isotopic data from 14 of these oceanic crust basalt samples. The δ26Mg values of most basalts from the three drill holes were higher (up to −0.10‰) than that of the average mantle (−0.25‰). The lack of correlations of δ26Mg with geochemical indices of magmatic processes (e.g., MgO, CaO/Al2O3, La/Sm, Nb/Zr) suggests that crystal fractionation and partial melting had insignificant effects on the Mg isotopic compositions of the South China Sea basalts. Thus, the variations in Mg isotopes were inherited from their mantle sources. Considering the highly varied Ce/Pb ratios and elevated 87Sr/86Sr values but mantle-like 143Nd/144Nd values, we propose that the varied δ26Mg values were likely caused by metasomatism of subduction-released fluids. The coupling of Mg and Sr-Fe isotopes provides robust evidence that the high-δ26Mg values of the South China Sea basalts resulted from mixing among pyroxenite-bearing peridotite mantle, the nearby Hainan plume materials, and subducting serpentinite-released fluids. Therefore, these Mg isotopes suggest that the mantle source of the South China Sea basalts was influenced by subducted materials, providing further evidence of the initial expansion, formation, and evolution of the South China Sea during plate subduction.

Underwater image enhancement recovers degraded underwater images to produce corresponding clear images. Image enhancement methods based on deep learning usually use paired data to train the model, while such paired data, e.g., the degraded images and the corresponding clear images, are difficult to capture simultaneously in the underwater environment. In addition, how to retain the detailed information well in the enhanced image is another critical problem. To solve such issues, we propose a novel unpaired underwater image enhancement method via a cycle generative adversarial network (UW-CycleGAN) to recover the degraded underwater images. Our proposed UW-CycleGAN model includes three main modules: (1) A content loss regularizer is adopted into the generator in CycleGAN, which constrains the detailed information existing in one degraded image to remain in the corresponding generated clear image; (2) A blur-promoting adversarial loss regularizer is introduced into the discriminator to reduce the blur and noise in the generated clear images; (3) We add the DenseNet block to the generator to retain more information of each feature map in the training stage. Finally, experimental results on two unpaired underwater image datasets produced satisfactory performance compared to the state-of-the-art image enhancement methods, which proves the effectiveness of the proposed model.

To better constrain Ca isotopic fractionation during volcanic magma differentiation, we report Ca isotope data for a series of volcanic glasses from the eastern Manus Basin that represent a continuum of compositions comprising basaltic andesite, andesite, dacite, and rhyolite. Our results show that these volcanic glasses exhibit ~0.25‰ variation in Ca isotopic compositions, with δ44/40Ca ranging from 0.81 ± 0.04 to 1.05 ± 0.04‰. The similar trace element patterns and Sr-Nd isotopic compositions exclude source heterogeneity as the cause of the varied Ca isotopic compositions. Due to their low K/Ca ratios and young age, the Ca isotopic variations cannot be attributed to 40K decay. Instead, the observed Ca isotopic variations are primarily controlled by their lithology. Specifically, δ44/40Ca of basaltic andesite (0.81 ± 0.04) and andesite (0.82 ± 0.01) are similar to the averages of reported mid-ocean ridge basalts (MORBs; 0.84 ± 0.10; 2SD, N = 26) and back-arc basin basalts (BABBs; 0.80 ± 0.08; 2SD, N = 21) in literature, but do not correlate with SiO2 or MgO contents, indicating the Ca isotopic fractionation is insignificant during intermediate-mafic magma evolution. As magma differentiation continues, δ44/40Ca of dacite and rhyolite evolves from 0.85 ± 0.01 to 1.05 ± 0.04‰. Moreover, δ44/40Ca of felsic glasses are negatively correlated with Eu/Eu*, which suggests that the increasing δ44/40Ca of felsic glasses is most likely related to plagioclase (Pl) fractional crystallization. Therefore, we conclude that Ca isotopes can behave differently at different stages of volcanic magma differentiation. Modeling of fractional crystallization using rhyolite-MELTS shows that the relative Ca fractions in crystallized minerals (e.g., Pl vs. Cpx) and the Ca isotopic fractionation factor between the residual melt and crystallized Pl (αmelt-Pl, which is likely related to the An number of Pl, magma temperature and kinetic effects during crystallization), provide a plausible explanation for the behavior of Ca isotopes during volcanic magma differentiation.

Urban stormwater flooding and pollution are severe issues due to connected impervious surfaces. Over recent decades, solutions to these issues have been towards stormwater source control measures. We developed an innovative cost-efficient stormwater infiltration filter, made of gravel-peat mixture and geotextile. Laboratory column tests were conducted to compare a range of volumetric ratios of gravel (limestone and silica) to peat regarding their heavy metal removal efficiency (RE). The tested heavy metals were cadmium, lead and zinc. All ratios had a high RE (95.9%-100%), despite very high initial metal concentrations. The 5LG:1P mixture (i.e., volumetric ratio of limestone gravel to peat was 5:1) had the highest RE (99.6%-100%) and is suggested as a good candidate for implementation. If a longer-term use is required, a 5SG:10LG:3P mixture (i.e., volumetric ratio of silica gravel, limestone gravel, and peat of 5:10:3) is recommended as it kept the high heavy metal RE with a lower clogging potential and lower cost than the 5LG:1P mixture. The most convenient but expensive filter material with high RE is limestone gravel alone. Finally, we proposed two field designs for implementing the infiltration filter, which incorporate concepts of “treatment train” and “good urban design”. We also provided some suggestions for the installation of gravel-peat infiltration filters.

Increasing evidence shows that the mantle contributes (directly or indirectly) to Sn-bearing granites worldwide. However, the specific role of mantle in the formation of tin granites and related mineralization remains poorly understood. In the world-class Dachang district, South China, tin mineralization is related to the Longxianggai equigranular/porphyritic biotite granites and tin orebodies are cut by granite porphyry dykes hosting mafic microgranular enclaves (MMEs). A combination of zircon U-Pb dating and Hf-O isotopes, mineral chemistry, and whole-rock elemental and Sr-Nd isotopic compositions—for granitic rocks and MMEs, is employed to constrain the petrogenesis and to unravel the link between tin fertility and mantle upwelling. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon U-Pb dating indicates that the biotite granites were emplaced at ca. 93 Ma, and the granite porphyry dykes and MMEs were formed at ca. 86 Ma. The biotite granites are silica- and alkali-enriched with A/CNK ratios of 1.04–1.36, and exhibit elevated concentrations of Li, F, P, Rb, Cs, Ta, Sn, W, and U, showing affinities with highly fractionated S-type granites. Whole-rock geochemical and Nd isotopic (εNd(t) = −10.0 to −7.8) data, and in situ zircon Hf-O (εHf(t) = −9.9 to −3.9, δ18O = 6.2–8.9‰) isotopes indicate that the biotite granites were formed by partial melting of metasedimentary rocks at relatively high temperatures (≥782 °C), possibly with minor input of mantle material. Likewise, the post-ore granite porphyry dykes have similar chemical and mineralogical characteristics as fractionated S-type granites. Zircon Hf-O isotopes (εHf(t) = −9.0 to −4.9, δ18O = 6.5–8.2‰) and whole-rock geochemical data suggest they were derived from a similar source as the biotite granites, whereas elevated εNd(t) values of −5.0 to −3.3 for granite porphyry dykes relative to biotite granites reveal an increasing mantle input. Distinct εNd(t) (−0.4 and −0.3) and zircon Hf-O (εHf(t) = 1.5–5.0, δ18O = 6.5–7.2‰) isotopes of the MMEs, suggest that the mafic melt could be sourced from the asthenospheric mantle, contaminated by subcontinental lithospheric mantle/continental crust during magma ascent, and hybridized by felsic melt at emplacement-level. The magmatic sequence in the Dachang district is indicative of an extensional tectonic setting where mantle-derived magmas are predicted to migrate to shallower crustal levels as the crust progressively becomes thinner and hotter. High-temperature partial melting of mature metasedimentary crust triggered by heat input from the upwelled mantle, may contribute to biotite breakdown, which is important for concentrating tin in melts. Fractional crystallization of initially Sn-rich felsic melts under reduced conditions makes further tin enrichment and produces Sn-bearing granites (the Longxianggai pluton). Prolonged mantle upwelling results in distinct magma mixing and the formation of granite porphyry dykes and MMEs. These dykes are highly fractionated with elevated Sn and W contents, which show great potential to form hydrothermal Sn-W mineralization.

Following the popularity of digital video application, video copying and dissemination have become very easy; however, this makes video hacking and piracy a potential threat in video communication. Video watermarking technology can solve the problem of copyright protection, and thus, it has been extensively researched. The robustness of the video watermarking algorithm in the bitstream domain is poor, especially the anti-recompression ability, since the watermarked video may be compressed again before transmitting. Considering this, this paper proposes a video watermarking algorithm in the bitstream domain based on moving object detection. To increase the robustness of the watermarking scheme, the moving macroblocks that belong to the moving object in each P frame can be identified via the moving object detection algorithm. Then, watermark embedding in the moving macroblocks is performed using codeword substitution to ensure the consistency of the bitstream. Moving object detection and watermark embedding are independent and are both carried out in the bitstream domain by partially decoding the bitstream; this avoids the complete decoding and reconstruction of the video, making the method to be highly efficient. The simulation results confirm that the proposed method is robust against recompression and has little impact on the video visual quality and no influence on the bit rate.

Polygala crotalarioides Buch.-Ham. ex DC. (Polygalaceae) is a perennial herbaceous plant widely distributed in southwest China. Its chloroplast genome sequence was obtained using Illumina NovaSeq sequencing technology, and then was assembled, annotated, and characterized. The total length of chloroplast genome is 164,269 bp and it contained a large (LCS, 82,697 bp) and a small (SSC, 8083 bp) single copy region, separated by a pair of inverted repeats (IRA/IRB, 36,744 bp). The overall GC content of genome was 36.8% and corresponding values of the LSC, SSC, and IR regions are 34.9%, 29.5%, and 39.7%, respectively. There are 135 genes that were predicted including 89 protein-coding, 38 tRNA, and 8 rRNA genes. The maximum-likelihood (ML) phylogenetic tree reconstructed by IQ-TREE indicated that P. crotalarioides had a strong genetic relationship with P. tenuifolia, P. sibirica, and P. japonica. In summary, the complete chloroplast genome of P. crotalarioides is reported for the first time, which is of great significance for future research on the evolutionary phylogeny and protection of Polygala.

The Indo-Pacific convergence region is the best target to solve the two remaining challenges of the plate tectonics theory, i.e., subduction initiation and the driving force of plate tectonics. Recent studies proposed that the Izu-Bonin subduction initiation belongs to spontaneous initiation, which implies that it started from extension, followed by low angle subduction. Numerical geodynamic modeling suggests that the initiation of plate subduction likely occurred along a transform fault, which put the young spreading ridge in direct contact with old oceanic crust. This, however, does not explain the simultaneous subduction initiation in the west Pacific region in the Cenozoic. Namely, the subduction initiations in the Izu-Bonin- Mariana, the Aleutian, and the Tonga-Kermadec trenches are associated with oceanic crusts of different ages, yet they occurred at roughly the same time, suggesting that they were all triggered by a major change in the Pacific plate. Moreover, low angle subduction induces compression rather than extension, which requires external compression forces. Given that the famous Hawaiian-Emperor bending occurred roughly at the same time with the onset of westward subductions in the west Pacific, we propose that these Cenozoic subductions were initiated by the steering of the Pacific plate, which are classified as induced initiation. Induced subduction initiation usually occurs in young ocean basins, forming single-track subduction. The closures of Neo-Tethys Oceans were likely triggered by plumes in the south, forming northward subductions. Interestingly, the Indian plate kept on moving northward more than 50 Ma after the collision between the Indian and Eurasian continents and the break-off of the subducted oceanic slab attached to it. This strongly suggests that slab pull is not the main driving force of plate tectonics, whereas slab sliding is.

New findings on behaviours of elements and the recycling of a variety of volatile components during plate subduction have been made by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences. C–H–O fluids show unexpected immiscibility at subduction zone conditions. First principles simulations reveal that high temperature greatly enhances the tendency of calcium partitioning into silicates, which implies that CaCO3 is unlikely to be the major carbon host in Earth's deep mantle. By integrating the results from this research program and the knowledge from previous studies, a unified picture of the global deep volatile cycle is provided. Carbon is the most important element on Earth, which is the core element of life. It has major influences not only on the climate change, but also on magmatic activities. The Earth's carbon is mainly stored in the mantle and the core in its reduced form such as diamond, graphite and carbide. Based on first-principle calculations and, high pressure experiments and geophysical results so far published, it is suggested that there should be a layer of ''carbonate mantle peridotite'' at the bottom of the upper mantle. The carbonatized layer may have acted as the source of severe climate fluctuations and mass extinction on the Earth. These progresses provide us a better understanding on the interactions between the Earth's interior and surface through plate subduction and mantle plume. Keywords: Plate subduction, Recycling, Element recycling, Volatile recycling

The history of the Hawaiian hotspot is of enduring interest in studies of plate motion and mantle flow, and has been investigated by many researchers using the detailed history of the Hawaiian-Emperor Seamount chain. One of the unexplained aspects of this history is the apparent offset of several Emperor seamounts from the Hawaii plume track. Here we show that the volcanic migration rates of the Emperor seamounts based on existing data are inconsistent with the drifting rate of the Pacific plate, and indicate northward and then southward “absolute movements” of the seamounts. Numerical modeling suggests that attraction and capture of the upper part of the plume by a moving spreading ridge led to variation in the location of the plume’s magmatic output at the surface. Flow of the plume material towards the ridge led to apparent southward movement of Meiji. Then, the upper part of the plume was carried northward until 65 Ma ago. After the ridge and the plume became sufficiently separated, magmatic output moved back to be centered over the plume stem. These changes are apparent in variations in the volume of seamounts along the plume track. Chemical and isotopic compositions of basalt from the Emperor Seamount chain changed from depleted (strong mid-ocean ridge affinity) in Meiji and Detroit to enriched (ocean island type), supporting declining influence from the ridge. Although its surface expression was modified by mantle flow and by plume-ridge interactions, the stem of the Hawaiian plume may have been essentially stationary during the Emperor period.

The Logit model and the Probit model are statistical models of Logistic regression and probability-based pattern recognition algorithms. The cases in which the Logit model and the Probit model fit better, respectively, are assessed to provide selection suggestions. Criteria, such as the AIC, Deviance, and Pseudo R-square, are selected to assess the goodness-of-fit of the two models. Using Monte Carlo simulation in different data scenarios found that some criteria have limited applicability in assessing the goodness of fit and two models are not sensitive to whether or not the independent variables are independent of each other. The difference between the two models is mainly in the sample size and the kurtosis of the data. The Probit model fits well to the smaller data set generated for all kurtosis cases, while the Logit model fits better when the sample size from the Leptokurtic distribution is larger.

Kimberlite is characterized by explosive eruption powered by excess carbon dioxides (CO2)1 and water2. Given that diamond is the dominant stable phase of carbon in the upper mantle3, it is obscure where does the excess CO2 in kimberlite has come from. Here we show that ferric iron oxidizes diamond at 1900K, 20GPa and 2000K, 25GPa, forming CO2. The lower mantle is dominated by bridgmanite, which is rich in ferric iron4. Bridgmanite decomposes once it is brought to the upper mantle, releasing extra ferric iron. Therefore, the oxidation of diamond may have been popularly occurring at the base of the upper mantle, forming CO2-rich carbonated domains that are the main source of kimberlite. The rising kimberlitic magma reaches the lithosphere mantle of thick cratons before it crosses the solidus line of mantle peridotite, and thus keeps its volatile-rich nature that drives explosive eruptions. When the lithospheric mantle is thinner than ~140 km, kimberlite changes into much less explosive magmas due to partial melting of mantle peridotite, and, consequently, entrained diamond is mostly oxidized during the magma’s slower ascension.

Background: Protein glutaminase specifically deamidates glutamine residue in protein and therefore significantly improves protein solubility and colloidal stability of protein solution. In order to improve its preparation efficiency, we exploited the possibility for its secretory expression mediated by twin-arginine translocation (Tat) pathway in Bacillus licheniformis. Results: The B. licheniformis genome-wide twin-arginine signal peptides were analyzed. Of which, eleven candidates were cloned for construction of expression vectors to mediate the expression of Chryseobacterium proteolyticum protein glutaminase (PGA). The signal peptide of GlmU was confirmed that it significantly mediated PGA secretion into media with the maximum activity of 0.16 U/ml in Bacillus subtilis WB600. A mutant GlmU-R, being replaced the third residue aspartic acid of GlmU twin-arginine signal peptide with arginine by site-directed mutagenesis, mediated the improved secretion of PGA with about 40% increased (0.23 U/ml). In B. licheniformis CBBD302, GlmU-R mediated PGA expression in active form with the maximum yield of 6.8 U/ml in a 25-l bioreactor. Conclusions: PGA can be produced and secreted efficiently in active form via Tat pathway of B. licheniformis, an alternative expression system for the industrial-scale production of PGA.How to cite: Niu D, Li C, Wang P, et al. Twin-arginine signal peptide of Bacillus licheniformis GlmU efficiently mediated secretory expression of protein glutaminase. Electron J Biotechnol 2019;42. https://doi.org/10.1016/j.ejbt.2019.10.006 Keywords: Arginine, Aspartic acid, Bacillus licheniformis, Bacillus subtilis, Escherichia coli, Prostaglandins A, Protein glutaminase, Protein sorting signals, Secretion expression, Signal peptide, Tat pathway

Plate subduction is the largest natural factory that processes elements, which controls recycling and mineralization of a variety of elements. There are three major ore deposit belts in the world: the circum-Pacific, the central Asian, and the Tethys belts. All the three belts are closely associated with plate subductions, the mechanism remains obscure. We approached this problem from systematic studies on the behaviours of elements during geologic processes. This contribution summaries the recent progress of our research group. Our results suggest that porphyry Cu deposits form through partial melting of subducted young oceanic crust under oxygen fugacities higher than ΔFMQ ∼+1.5, which is promoted after the elevation of atmospheric oxygen at ca. 550 Ma. Tin deposits are associated with reducing magmatic rocks formed as a consequence of slab rollback. The Neo-Tethys tectonic regime hosts more than 60% of the world’s total Sn reserves. This is due to the reducing environment formed during the subduction of organic rich sediments. For the same reason, porphyry Cu deposits formed in the late stages during the closure of the Neo-Tethys Ocean. Tungsten deposits are also controlled by slab rollback, but is not so sensitive to oxygen fugacity. Subduction related W/Sn deposits are mostly accompanied by abundant accessory fluorites due to the breakdown of phengite and apatite. Decomposition of phengite is also significant for hard rock lithium deposits, whereas orogenic belt resulted from plate subduction promote the formation of Li brine deposits. Cretaceous red bed basins near the Nanling region are favorable for Li brines. Both Mo and Re are enriched in the oxidation-reduction cycle during surface processes, and may get further enriched once Mo-, Re-enriched sediments are subducted and involved in magmatism. During plate subduction, Mo and Re fractionate from each other. Molybdenum is mainly hosted in porphyry Mo deposits and to a less extent, porphyry Cu-Mo deposits, whereas Re is predominantly hosted in porphyry Cu-Mo deposits and sedimentary sulfide deposits.

In this paper, we design, analyze and numerically validate an unconditionally energy stable second order numerical method for solving the Allen–Cahn equation which represents a model for anti-phase domain coarsening in a binary alloy. The proposed scheme inherits the property of the decrease of the total energy from the Allen–Cahn equation. An error estimate for the fully discretized scheme is also established. Numerical examples are presented to confirm the accuracy, efficiency, and stability of the proposed method. In particular, the method is shown to be unconditionally energy stable and second order accurate in both time and space discretizations.

Apatite as an excellent tracer of the magmatic and metallogenic processes, can incorporate large amounts of trace elements sensitive to melting and/or ore-fluid evolution. This paper reports a combined study of in situ apatite geochemistry and whole-rock geochemistry for Early Cretaceous ore-bearing (Group I) and ore-barren porphyries (Group II) in the Liguo Fe-Cu-Au deposit for the deciphering of its petrogenesis and the control factors of mineralization. The apatite from both Group I and Group II is magmatic fluorapatite, characterized by Eu negative anomalies, an enrichment of LREEs, and a depletion of HREEs. Meanwhile, both groups have high Sr/Y and delta Eu, indicating porphyry adakitic characteristics in origin. Compared to isotopes of whole rocks, the variable Sr-87/Sr-86 (0.70250-0.71262) and delta O-18 (6.22-9.00) values of both groups of apatite imply contributions of mantle-, crust- and/or sediment-derived materials. Although Group I apatite and II apatite show some similar geochemical characteristics, Group I apatite precedes the crystallization of plagioclase with no Sr-(La/Yb)(N)/(La/ Sm)(N)/(Sm/Yb)(N) correlations, whereas Group II apatite coincides with plagioclase crystallization, displaying positive correlations. The geochemistry of the elements (delta Eu, delta Ce, MnO and V) of these apatite groups, which are sensitive to a redox state, shows high oxygen fugacity (between HM and NNO), and Group I apatite has systematically higher oxygen fugacity than Group II apatite. More importantly, these different trace elements and oxygen fugacity characteristics between Group I apatite and Group II apatite can be used as an indicator of mineralization, and allow the skarn Fe-Cu-Au mineralization range to be drawn for the first time. Furthermore, the estimated F and Cl contents of the host parent magma (F = 1300-2446 ppm, Cl = 140-4780 ppm) are higher than those in a primitive mantle and average continental crust, suggesting an enrichment process of F and Cl. According to the above adakitic characteristics, high oxygen fugacity, and high F and Cl contents, the Pacific Plate subduction may be the main dynamic mechanism of the diagenesis and mineralization found in Liguo.

The water and sediment yields of rivers are changing substantially under the impacts of climate variability and anthropogenic activities, which are increasingly becoming an important research topic in the field of hydro-environmental science. This study presents a comprehensive investigation of the changes in runoff depth (h), specific sediment yield (SSY), and flow-sediment relationship at multi-temporal scales in the Han River Basin (HRB). The effects of climate variability and anthropogenic activities on SSY were quantified by employing double cumulative curve analysis. The results are as follows: (1) The annual and flood season h and SSY in the midstream (Huangzhuang Station) during the past six decades presented declining trends. The detected change points (i.e., 1968 and 1984) in SSY were linked to the reservoir and dam construction and soil and water conservation programs. The Danjiangkou (DJK) Reservoir impounded water in the flood season and supplied water in the non-flood season, which made the intra-annual distributions of h and SSY more even and the intra-annual variations more moderate in the comparisons between the pre- and post-change periods. (2) The annual and flood-season flow-sediment relationships were fitted with the power function and the sediment productive ability of runoff in the flood season was much greater than that in the non-flood season. The construction and operation of the DJK Reservoir intercepted a significant quantity of sediment; thus, the sediment transported by unit runoff largely declined. (3) The estimated relative contributions of climate variability and anthropogenic activities to the changes in SSY suggested that the anthropogenic activities played a more substantial role in the SSY decline after the transition years. Sustainable development of the HRB will face many challenges as the water and sediment discharges decrease further from the Han River into the Yangtze River. These results will provide a reference for better soil and water resource conservation and draw more attention to strengthen the river basin management.

Rocks and ore deposits in subduction zones can provide clues to material cycling and related subduction processes. Here we demonstrate, based upon a new data compilation from more than 240 late-Mesozoic fluorite deposits in southeast China that most of them can be divided into three fluorite deposit belts (FDB) with distinct ages and orientations. The two older inland FDB with a NE-SW orientation were formed at 165–150 Ma and 150–130 Ma, respectively, whereas the younger coastal FDB, roughly perpendicular to the others, was generated at 110–70 Ma. The temporal-spatial distributions of the FDB are compatible with the subduction of the (paleo-) Pacific plate. We propose that the genesis of the earlier two inland FDB was due to northeastward slab rollback during low-angle subduction, while formation of the coastal FDB resulted mainly from high-angle northwestward hot/warm subduction. Large amounts of F, mainly derived from the decomposition of phengite (±apatite) in the subducted slabs, could be transported into the overlying crust via F-rich fluids and alkalic magmas. Subsequently, extensive crustal magmatism and fluid activities associated with subduction further concentrate F from the magmas and/or wall-rocks and facilitate fluorite mineralization. This study provides new insights into the interaction between the subducting (paleo-) Pacific plate and overlying eastern Eurasian continent in the late Mesozoic. It also highlights the potential genetic association of F transport/deposition with plate subduction that could be a common phenomenon in ancient and modern subduction zones.

China has made some progress in controlling PM2.5 (particulate matter with an aerodynamic diameter of &le, 2.5 &mu, m) pollution, but there are still some key areas that need further strengthening. Considering that excessive prevention and control efforts affect economic development, this paper combined an empirical orthogonal function, a continuous wavelet transform, and a concentration-weighted trajectory method to study joint regional governance during key pollution periods to provide suggestions for the efficient control of PM2.5. The results from our panel of data of PM2.5 in China from 2016 to 2018 could be decomposed into two modes. In the first mode, the pollution center was in central Shaanxi Province, and the main eruption period was from November to January of the following year. As the center of this region, Xi&rsquo, an should cooperate with the four cities in eastern Sichuan (Nanchong, Guangan, Bazhong, and Dazhou) to control PM2.5, since the eruption occurred in this area. Moreover, governance should last for at least two cycles, where one cycle is at least 23 days. The pollution center of the second mode was in the western part of Xinjiang. Therefore, after the prevention and control efforts during the first mode are completed, the regional city of Kashgar should continue to build a joint governance zone for PM2.5 along the Tianshan mountains in the east, focusing on prevention and control over two cycles (where one cycle is 28 days).

The self-assembly structures of dumbbell-shaped supramolecules are investigated using a simple sphere-rod-sphere (SRS) model. Through the simulated annealing Monte Carlo simulation under NVT condition, two variations of this model, i.e. the rigid/semi-rigid model, are compared by their order parameters. We found that, by varying the interactions of this SRS model, various nanostructures such as cross-linked networks, clusters phases, bundle-like nanowires and other order phases are discovered. The formation mechanism of these novel nanostructures is discussed.