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Radermachera sinica (China doll) is a popular evergreen horticultural crop worldwide. However, little information has been provided to describe the anthracnose disease of R. sinica. In 2018, symptoms suspected of leaf anthracnose were observed on R. sinica in gardens and commercial greenhouses in Guangzhou, China. Lesions on diseased leaves showed thinned and grayish white centers, dark-brown to black borders, and raised black spots. Twenty-seven single-conidia isolates were obtained from symptomatic leaf lesions. Based on morphological characteristics and multilocus phylogenetic analysis, 19 isolates were identified as Colletotrichum siamense and six and two isolates were identified as C. fructicola and C. karstii, respectively. An in vivo pathogenicity test was conducted on leaves of R. sinica plants, and it was discovered that C. siamense was more aggressive under wounded conditions than under unwounded conditions, and caused symptomatic necrotic lesions on the leaf. Afterward, the same pathogen was reisolated from lesions of inoculated leaves to fulfill Koch’s postulates. However, neither C. fructicola nor C. karstii caused visible lesions on leaves of R. sinica under wounded or unwounded conditions, indicating that they may be asymptomatic endophytes or opportunistic pathogens on R. sinica. To our knowledge, this study is the first report of Colletotrichum spp. associated with anthracnose disease on R. sinica in China.

The purpose of this work is to study the accelerated aging behavior of a room-temperature vulcanized (RTV) silicone rubber anti-pollution flashover coating. Red, blue and gray RTV rubber samples were selected to prepare coatings on the surface of stainless-steel sheets. The accelerated aging test was carried out in an aging test chamber according to a four-step program cycle. After the completion of different aging tests, the color difference, glossiness, surface micromorphology, wettability, insulation performance and other parameters of the samples were measured using colorimetry, infrared spectrometry, scanning electron microscopy, and a high-voltage breakdown tester. The results showed that with the increase in aging time, the color difference ∆Eab of the coatings increased. The G60 gloss value decreased gradually and tended to be saturated after 60 cycles. After the aging tests, the RTV coating surface had holes, cracks, peeling and other damage to varying degrees. The C:Si atomic ratio was less than 2, and the hydrophobicity was obviously deteriorated. After aging, the electrical strength of the three RTV coatings decreased significantly. It can be concluded that during the accelerated aging test, the RTV coating had cross-linking and oxidation reactions, and the internal deterioration and surface damage of the coating led to changes in its color, luster, morphology, insulation strength, etc.

Carbonate recycling in subduction zones has a strong influence on arc magmatism and carbon reservoirs in the mantle. However, geochemical evidence of carbonate recycling during subduction, especial...

Viral replication and movement are intimately linked; however, the molecular mechanisms regulating the transition between replication and subsequent movement remain largely unknown. We previously demonstrated that the Barley stripe mosaic virus (BSMV) γb protein promotes viral replication and movement by interacting with the αa replicase and TGB1 movement proteins. Here, we found that γb is palmitoylated at Cys‐10, Cys‐19, and Cys‐60 in Nicotiana benthamiana, which supports BSMV infection. Intriguingly, non‐palmitoylated γb is anchored to chloroplast replication sites and enhances BSMV replication, whereas palmitoylated γb protein recruits TGB1 to the chloroplasts and forms viral replication‐movement intermediate complexes. At the late stages of replication, γb interacts with NbPAT15 and NbPAT21 and is palmitoylated at the chloroplast periphery, thereby shifting viral replication to intracellular and intercellular movement. We also show that palmitoylated γb promotes virus cell‐to‐cell movement by interacting with NbREM1 to inhibit callose deposition at the plasmodesmata. Altogether, our experiments reveal a model whereby palmitoylation of γb directs a dynamic switch between BSMV replication and movement events during infection.

Salicylic acid (SA) acts as a signaling molecule to perceive and defend against pathogen infections. Accordingly, pathogens evolve versatile strategies to disrupt the SA-mediated signal transduction, and how plant viruses manipulate the SA-dependent defense responses requires further characterization. Here, we show that barley stripe mosaic virus (BSMV) infection activates the SA-mediated defense signaling pathway and upregulates the expression of Nicotiana benthamiana thioredoxin h-type 1 (NbTRXh1). The γb protein interacts directly with NbTRXh1 in vivo and in vitro. The overexpression of NbTRXh1, but not a reductase-defective mutant, impedes BSMV infection, whereas low NbTRXh1 expression level results in increased viral accumulation. Similar with its orthologs in Arabidopsis (Arabidopsis thaliana), NbTRXh1 also plays an essential role in SA signaling transduction in N. benthamiana. To counteract NbTRXh1-mediated defenses, the BSMV γb protein targets NbTRXh1 to dampen its reductase activity, thereby impairing downstream SA defense gene expression to optimize viral cell-to-cell movement. We also found that NbTRXh1-mediated resistance defends against lychnis ringspot virus, beet black scorch virus, and beet necrotic yellow vein virus. Taken together, our results reveal a role for the multifunctional γb protein in counteracting plant defense responses and an expanded broad-spectrum antibiotic role of the SA signaling pathway.

At present, the common protection technology of power-transmission and transformation equipment is mainly coating protection and hot-dip zinc protection. However, due to the low adhesion of epoxy zinc-rich coating, and the poor compatibility with top paint, environmental pollution, complex processing, high energy consumption and other defects of the hot-dip zinc process, its development is limited. In view of the above deficiencies, new anti-corrosion coating materials and processes were investigated in this study. Zinc coatings and Al-Zn coatings were prepared on the C45 steel matrix by hot-spraying and cold-spraying processes. The macro appearance, micromorphology and phase composition analysis of the coatings were evaluated. The adhesion of the coating to the substrate after the salt-spray test was tested. The results showed that the hot dip zinc coating and hot spray zinc coating had obvious cracking after the salt-spray test. The surface structure of cold-sprayed Al-Zn coating was relatively dense after the salt-spray test. The critical load of the cold-sprayed Al-Zn coating after the salt-spray test was higher than that of the other two coatings. The corrosion resistance to salt spray of cold-sprayed Al-Zn coating was demonstrated to be better than the hot-dip zinc coating, and thus has great application prospects.

First report of tomato yellow mottle-associated virus infecting Solanum nigrum in China Zhenggang Li, Yafei Tang, Xiaoman She, Guobing Lan, Lin Yu, and Zifu He† Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P. R. China. Tomato yellow mottle-associated virus (TYMaV) is a newly found cytorhabdovirus associated with epinasty of leaflet blades, yellow spots, puckering, and mottling symptoms in tomato plants in China (Xu et al., 2017). In May 2020, Solanum nigrum plants exhibiting leaf crinkling and mosaic symptoms (eXtra S1) were found in Shantou city, Guangdong, China. To identify the causal pathogens, the leaves of three symptomatic plants were collected and subjected to total RNA extraction with TRIzol Reagent (Takara, Kusatsu, Japan). About 100 μg RNA mixture, which consisted of an equal amount of total RNA extracted from the three samples, was subjected to small RNA deep sequencing and assembly (sRSA) (Kreuze et al., 2009). Small RNA cDNA library was constructed with the method described previously (Mi et al., 2008). Small RNA deep sequencing was performed with Illumina HiSeq X Ten platform. VirusDetect (Zheng et al., 2017) was used to analyze the sequence data. The result showed that the sequence data includes about 11 million reads and generated 194 unique contigs after removal of host-derived contigs. Subsequently, the unique contigs were screened using BLASTn search against the virus database. One hundred and five unique contigs were mapped to TYMaV genome (reference sequence, KY075646), 21 unique contigs were mapped to RNA1 segment of tomato chlorosis virus (ToCV) genome (reference sequence, KY618796), 67 unique contigs were mapped to RNA2 segment of ToCV genome (reference sequence, KY618797), and one unique contig was mapped to pepper veinal mottle virus (PVMV) genome (reference sequence, FJ617225) (eXtra S1). To verify the sRSA result for TYMaV detection, RT-PCR was performed with two primer pairs TYMaV-F1/R1 (5'-TCATTAGACTCAGGCCTAATCCTCA AAGT-3'/5'-GATATGGAGACGTCCAAGTTCAAAGGGATGGA-3'), and TYMaV-F2/R2 (5'-TATGCGGCAGCTTTCATGTCTATAGACCCT-3'/5'-ATGACCTAGCTTCAATAACAGTCGCG-3'), which are designed according to the sRSA result. All the symptomatic samples tested positive for TYMaV (eXtra S2). Western blot with TYMaV N protein-specific antibody further verified the result (eXtra S2). To obtain the nearly full-length sequence of TYMaV identified in Shantou, 13 primer pairs were designed to amplify the viral fragments. The amplified PCR products were then introduced into pMD19T (Takara, Kusatsu, Japan) and sequenced by Sangon Biotech Co. (Shanghai, China). The nearly full-length sequence of TYMaV Shantou isolate (TYMaV-ST) was assembled from the 13 overlapping sequences (reference sequence, MW527091). TYMaV-ST genome comprises of 13401 nt and shares 84.93% nucleotide sequence identity with the reference genome (KY075646). In addition, 37 S. nigrum samples and 20 tomato samples nearby with viral disease symptoms were collected from different sites of Guangdong province, China. Six S. nigrum samples and five tomato plant samples tested positive for TYMaV by RT-PCR, suggesting a wide spread of the virus in the surveyed region. These results together with those of the sRSA assay also suggest that the disease symptoms shown in the original S. nigrum plants may not necessarily be caused by TYMaV or by TYMaV alone. To our knowledge, this is the first report of TYMaV infecting S. nigrum in China. S. nigrum is a common weed which belongs to the family Solanaceae and may serve as a reservoir for TYMaV in the fields. Further research is needed to verify whether this is indeed the case, and to understand the characteristics of this virus including its transmission, pathogenicity, and economic significance. The authors declare no conflict of interest. Funding This work was supported by the Key Research and Development Program of Guangdong Province (2018B020202006), the Agricultural Competitive Industry Discipline Team Building Project of Guangdong Academy of Agricultural Sciences (202103TD and 202105TD), the Science and Technology Program of Guangzhou (202102020504), and Special Fund for Scientific Innovation Strategy-Construction of High-Level Academy of Agriculture Science (R2019PY-QF003). References: Kreuze, J. F., et al. 2009. Virology. 388: 1. Mi, S., et al. 2008. Cell. 133: 116. Xu, C., et al. 2017. J Virol. 91: 11. Zheng, Y., et al. 2017. Virology. 500: 130.

Salicylic acid (SA) acts as a signaling molecule to perceive and defend against pathogen infections. Accordingly, pathogens evolve versatile strategies to disrupt the SA-mediated signal transduction. However, it is necessary to further characterize how plant viruses manipulate the SA-dependent defense responses. Here, we show that Barley stripe mosaic virus (BSMV) infection activates SA-mediated defense signaling pathway and upregulates the expression of Nicotiana benthamiana thioredoxin h-type 1 (NbTRXh1). The γb protein interacts directly with NbTRXh1 in vivo and in vitro. Overexpression of NbTRXh1, but not a reductase-defective mutant, impedes BSMV infection, whereas low NbTRXh1 expression level results in increased viral accumulation. Similar with its orthologues in Arabidopsis, NbTRXh1 also plays an essential role in SA signaling transduction in N. benthamiana. To counteract NbTRXh1-mediated defenses, the BSMV γb protein targets NbTRXh1 to dampen its reductase activity and thereby impairing downstream SA defense genes expression to optimize viral cell-to-cell movement. We also found that NbTRXh1-mediated resistance defends against Lychnis ringspot virus, Beet black scorch virus, and Beet necrotic yellow vein virus. Taken together, our results reveal a novel role for the multifunctional γb protein in counteracting plant defense responses, and broadens the broad-spectrum antibiotic role of SA signaling pathway.One sentence summaryBSMV γb protein impairs NbTRXh1 reductase activity and dampen downstream SA-related genes expression to facilitate viral cell-to-cell movement.

Ferromanganese nodules are a potential energy resource because of their high contents of economically interesting elements (i.e. Mn, Ni, Cu, and Zn). These are higher in diagenetic layers than in hydrogenetic layers. The study of the causes of elemental accumulation in the diagenetic layer is useful for the exploration metal-rich nodules. A diagenetic-dominant ferromanganese nodule, from the central Clarion–Clipperton Fracture Zone of the eastern Pacific Ocean was studied from core to rim. It was divided into four layers and seven sublayers, of the four typical diagenetic sublayers (L1, L2-1, L2-2, and L3-1). Differences were observed in these diagenetic sublayers. L1 presents the highest Mn/Fe ratio (54), the lowest Co content (2262 ppm), and a positive Ce anomaly. L2-1 exhibits high Co (3122 ppm) and Ba contents (4020 ppm), a positive Ce anomaly, and an obvious peak for 10 Å manganate minerals. L2-2 contains the lowest Ni+Cu contents (3.2 wt%), the highest Ba and Co contents (5110 ppm), and the strongest positive Ce anomaly. In L2-2, the δCe value can be positively correlated to the Mn/Fe ratio and a pronounced peak for 10 Å manganate minerals indicates that this layer has the highest mineral crystallinity. L3-1 shows the highest Ni+Cu contents (5.4 wt%), the lowest Ba (1247ppm), and Co (1725 ppm), a weakly positive Ce anomaly, and the poorest mineral crystallization. Diagenetic- and hydrogenetic-endmember mixing models reveal that hydrogenetic input contributes minimally to these chemical changes, whereas diagenetic input contributes greatly. The changes in diagenetic input may be caused by the changes in primary productivity brought about by movement of tectonic plates and the intense activity of the diagenetic pore fluid. The activity may provide a metal source for the diagenetic sublayer (anomalously high Co and Ce content) via the incorporation of metals released from dissolved buried nodules and micronodules under a suboxic or reducing environments.

Manganese nodules are a potential source of critical metals such as Cu, Ni, and Co and are widely distributed on the abyssal plains of the global oceans. A polymetallic nodule metallogenic belt with a heterogeneous and spatially clustered nodule distribution was recently discovered in NW Pacific inter-seamount basin (NPIB) areas. However, the geological processes that regulate the nodule occurrence in that region are unresolved. Here, we report on the characteristics of a high-density field of manganese nodules in the abyssal plain north of Suda Seamount. Ship-borne multibeam bathymetric data reveal a typical seamount sector-collapse topography characterized by radial lineaments of debris channels and ridges formed by rapid debris-avalanche flow. Backscatter data linked with underwater observation indicate that manganese nodules are more concentrated (50%–80% areal coverage) along the main body of the debris apron compared to adjacent neighboring areas (

Dehydrated fluids expelled from serpentinized mantle in the subducted slab are gradually recognised as a vital role in generating arc magmatism and element cycling in the Earth. However, it remains not clear about their recycling at various depth in subduction zones and if slab serpentinite-derived fluids contribute to the genesis of lavas from the back-arc basins. Here, we study the magnesium (Mg) isotopic compositions of lavas from the Okinawa Trough (OT) and Lau basin (LB) as Mg isotopes have shown great potential to trace dehydration of slab serpentinites in recent years. Overall, lavas from the OT and LB have averagely heavier Mg isotopic compositions relative to the mid-ocean ridge basalt (MORB) mantle, which could be attributed to the involvement of slab serpentinite-derived fluids rather than crustal assimilation or input of subducted sediments as indicated by the isotopic modelling results. The δ26Mg values of the southern OT (SOT) and southern LB (SLB) are generally higher than the middle OT (MOT) and northern LB (NLB), respectively, with an average of -0.11 ± 0.06‰ (2SD, n=5) for the SOT, -0.20 ‰ ± 0.04 (2SD, n=5) for the MOT, -0.13 ‰ ± -0.08 for the SLB (2SD, n=6) and -0.19 ‰ ± 0.06 (2SD, n=10) for the NLB. The binary modelling results have shown that various amounts of serpentinite-derived fluids could explain the variations in Mg isotopic compositions observed in the OT and LB. Combined published δ26Mg values in subduction zones with our data, the thermal structure of inter-subduction zone may play a first control on the signal of Mg-rich serpentinite-derived fluids. By contrast, the contributions of these fluids to different segments in a specific subduction zone may depend on the slab depth beneath magmatic activity sites.

Magmatic sulfide formation and oxidative dissolution are effective in metal pre-enrichment and remobilization during magmatic processes, and are considered to be a prerequisite for the formation of magmatic–hydrothermal ore deposits in subduction zones. However, this sequential process and sulfide oxidation mechanism are poorly understood. In this study, we report fine-grained sulfides with variable degrees of oxidation distributed within mafic cumulates, brought into felsic magma as mafic magma intrusions in the southwestern Okinawa Trough. Thermodynamic modeling suggests that the oxygen fugacity (fO2) of primitive mafic magma is ∼FMQ + 2.5, reducing to ∼FMQ + 1 in evolved mafic magma and to ∼FMQ + 0.5 in felsic magma. This variation results from the continuous assimilation of reduced country rocks, as reflected by negative δ34SVCTD values (–0.62‰ ± 0.23‰) of magmatic sulfides and highly radiogenic Sr–Nd isotopic compositions of host dacite. Magmatic reduction and addition of crust-derived sulfur result in early formation of crystalline sulfides, dominantly pyrrhotite, enriched in Cu (0.93 ± 0.38 wt.%). A new injection of oxidized mafic magma triggers partial to complete oxidation of the earlier magmatic sulfides, ultimately transforming them into hematite–magnetite (HM) intergrowths. This means that sulfide oxidation is not directly associated with the mafic magma itself, but more likely with high-fO2 magmatic fluid exsolved from the primitive mafic magma. The oxidative dissolution process releases >90% of Cu from the primary sulfides, with this Cu preferentially moving into magmatic fluid. This indicates that metal remobilization and transfer is very efficient under HM buffer conditions, in which trisulfur S3− ions with high affinities for Au and Cu are probably the dominant sulfur species. We suggest that the periodic injection of oxidized mafic magma into continental crust containing reduced lithologies is essential for the sequential process of early sulfide formation and later oxidative dissolution in the Okinawa Trough and in other subduction zone settings with similar tectono-magmatic conditions. This process could be a precursor to the generation of metal-bearing magmatic fluid, contributing to mineralization in subduction zones.

Objective: To investigate the impact of enhanced recovery after surgery (ERAS) nursing combined with limb training on knee joint function and neurological function after total knee arthroplasty in patients with knee osteoarthritis (KOA). Methods: Eighty-six patients with KOA after TKA were randomly divided into two groups, group A and group B, with 43 patients in each group. Group A was given ERAS nursing, and group B was given limb rehabilitation training combined with ERAS nursing. The changes in knee joint function and neurological function were observed. Results: There was no significant difference in the time to get out of bed for the first time, first bowel movement time after the surgery, hospital stay and hospital costs between the two groups (P>0.05). There was no significant difference in VAS scores between the two groups before the operation and 1 d after the operation (P>0.05). Three days and seven days after the operation, the VAS scores in the two groups both decreased, and the VAS scores of group B were higher than those of group A (P0.05), but the two indicators in the two groups all increased at three and six months after the operation, and the two indicators in group B were higher than those of group A (P0.05). Fifteen and thirty days after the operation, the NIHSS scores of the two groups both decreased, and the NIHSS scores of group B were lower than those of group A (P

Robot intelligent grasping plays an important role for achieving robot intelligence. With the complexity of the shape and size of the object to be grasped and the grasping environment, the traditional grasping technology can no longer meet the intelligent requirements. This article establishes a target grasping network model based on deep reinforcement learning, sets a task of grasping parts as the Markov decision process, uses deep Q learning networks for training, and uses fully convolutional networks to approximate the Actions − Values function in Q learning, which selects the best grasping action by maximizing the Q function. Finally, the feasibility of the established model is verified by simulation.

Nine genera of viruses in five different families use triple gene block (TGB) proteins for virus movement. The TGB modules fall into two classes: hordei-like and potex-like. Although TGB-mediated viral movement has been extensively studied, determination of the constituents of the viral ribonucleoprotein (vRNP) movement complexes and the mechanisms underlying their involvement in vRNP-mediated movement are far from complete. In the current study, immunoprecipitation of TGB1 protein complexes formed during Barley stripe mosaic virus (BSMV) infection revealed the presence of the γb protein in the products. Further experiments demonstrated that TGB1 interacts with γb in vitro and in vivo, and that γb-TGB1 localizes at the periphery of chloroplasts and plasmodesmata (PD). Subcellular localization analyses of the γb protein in Nicotiana benthamiana epidermal cells indicated that in addition to chloroplast localization, γb also targets the ER, actin filaments and PD at different stages of viral infection. By tracking γb localization during BSMV infection, we demonstrated that γb is required for efficient cell-to-cell movement. The N-terminus of γb interacts with the TGB1 ATPase/helicase domain and enhances ATPase activity of the domain. Inactivation of the TGB1 ATPase activity also significantly impaired PD targeting. In vitro translation together with co-immunoprecipitation (co-IP) analyses revealed that TGB1-TGB3-TGB2 complex formation is enhanced by ATP hydrolysis. The γb protein positively regulates complex formation in the presence of ATP, suggesting that γb has a novel role in BSMV cell-to-cell movement by directly promoting TGB1 ATPase-mediated vRNP movement complex assembly. We further demonstrated that elimination of ATPase activity abrogates PD and actin targeting of Potato virus X (PVX) and Beet necrotic yellow vein virus (BNYVV) TGB1 proteins. These results expand our understanding of the multifunctional roles of γb and provide new insight into the functions of TGB1 ATPase domains in the movement of TGB-encoding viruses., Author summary Plant viruses employ varied movement strategies to mediate local and systemic infections. Viral ribonucleoprotein (vRNP) movement complexes comprising either the hordei- or potex-like triple gene block (TGB) and viral RNAs represent important models for plant virus movement. However, the constituents of viral ribonucleoprotein (vRNP) movement complexes as well as their biological significance in vRNP assembly and subsequent interactions are far from complete. Additionally, the mechanistic roles of the highly conserved TGB1 ATPase domain in vRNP-mediated movement remain an enigma. Here, we demonstrate that the γb protein acts as a novel positive regulator of BSMV cell-to-cell movement by directly interacting with the TGB1 protein. In vitro biochemical assays verified an essential role of TGB1 ATPase-mediated ATP hydrolysis in assembly of vRNP movement complexes, a process that can be further enhanced by the γb protein. We also extend our studies of BSMV TGB1 ATPase to those of PVX and BNYVV, and suggest a model for an evolutionally conserved mode of energy-coupled vRNP movement complex assembly among different TGB-encoding viruses. Our results address the knowledge gap between TGB1 ATPase activity and vRNP movement complex assembly and expand our understanding of the multifaceted roles of γb in BSMV infection.

The northern Lau back-arc basin (NLB) lavas display a diverse geochemical nature caused by complex geological processes in this region. Independent component (IC) analysis was applied to investigat...

It is generally accepted that in the Late Mesozoic, >100 km of ancient refractory lithospheric mantle beneath the eastern part of the North China Craton (NCC) was removed and replaced by young and fertile mantle material. However, the mechanisms and a tectonic model for this lithospheric destruction remain subjects of debate. To elucidate this lithospheric destruction, an investigation that included whole-rock geochemical analyses, zircon U–Pb age determinations, and in situ Hf–O isotope analyses of samples from the Tiezhai syenite porphyry and mafic rocks from western Shandong Province (the Luxi terrane) was conducted. Zircon U–Pb dates reveal that the Tiezhai syenite porphyry, gabbro, and monzonite were emplaced during the Early Cretaceous (weighted-mean 206Pb/238U ages of 130–129 Ma). Abundant Mesoarchean–Paleoproterozoic inherited zircons/cores were identified in both the syenite porphyry and the gabbro, yielding 207Pb/206Pb ages of 2.95–2.34 Ga. Both the syenite porphyry and mafic rocks are metaluminous, high-K calc-alkaline rocks enriched in large ion lithophile elements (e.g., Rb, Sr, and Ba) and light rare earth elements, and depleted in high field strength elements (e.g., Nb, Ta, and Ti) and heavy rare earth elements. The samples and have no obviously Eu anomalies. The syenite porphyry has high Sr and La contents, high Sr/Y (196–292) and (La/Yb)N (24.8–36.2) ratios, and low Y and Yb contents, similar to adakitic rocks. The Tiezhai syenite porphyry has a relatively narrow range of (87Sr/86Sr)i ratios (0.7057–0.7059), eNd(t) values (−8.9 to −6.8), and relatively high radiogenic Pb isotopic compositions [(206Pb/204Pb)i = 18.36–18.37, (207Pb/204Pb)i = 15.54–15.55, and (208Pb/204Pb)i = 38.25–38.31]. The Tiezhai mafic rocks can be divided into two groups (1 and 2) based on their whole-rock Sr, Nd, and Pb isotopic compositions. Group 1 has lower (87Sr/86Sr)i ratios than group 2 (0.7046–0.7047 vs. 0.7072–0.7096), lower radiogenic Pb isotopic compositions [(206Pb/204Pb)i = 17.68–17.71 vs. 18.08–18.12; (207Pb/204Pb)i = 15.44–15.45 vs. 15.52–15.53; (208Pb/204Pb)i = 37.72–37.98 vs. 40.17–40.60], and slightly higher eNd(t) values (−8.0 to −7.1 vs. –10.8 to −8.2). The syenite porphyry and gabbro from group 2 have similar narrow ranges of zircon rim eHf(t) values (mostly between −4 and + 2), and high zircon rim δ18O values (syenite porphyry = 6.9‰–9.0‰; gabbro = 7.7‰–9.1‰), and low inherited zircon/core δ18O values (syenite porphyry = 5.8‰–6.9‰; gabbro = 5.7‰–6.9‰). The Tiezhai mafic rocks were probably derived from partial melting of the Luxi EM1-asthenospheric mantle previously metasomatized by fluids derived from subducted oceanic crust and sediments. The melts probably assimilated ancient NCC upper crust material (~5% assimilated by group 1 mafic rocks, 20%–30% assimilated by group 2 mafic rocks) during magma ascent. The Tiezhai syenite porphyry was most likely derived from partial melting of the newly underplated thick lower crust and assimilated ~10% of the ancient NCC upper crust material during ascent. The addition of fluids derived from oceanic crust and sediments to the overlying subcontinental lithospheric mantle during subduction was an important factor contributing to lithosphere destruction in the eastern NCC. Slab rollback, together with the ridge subduction of the paleo-Pacific slab beneath the eastern NCC, is the most reasonable tectonic model for NCC destruction and formation of the Early Cretaceous large-scale magmatic rocks in the eastern NCC.

Sulphur isotopes can be used as a powerful tool to trace fluid evolution and explore the formation of chimneys. To clarify the in situ S isotopic variations of sulphides at the micro-scale, we analyzed a sulphide chimney collected from the hydrothermal field in the East Pacific Rise 1–2° S using a sensitive high-mass-resolution ion micro-probe for stable isotopes (SHRIMP SI). Three mineral zones can be identified in the chimney: an external outer wall of porous anhydrite and colloform pyrite, an internal middle zone of sub-euhedral pyrite and massive chalcopyrite, and an inner zone of massive pyrite. The δ34SV-CDT values of the sulphides fall within the range 1.83–7.51 ‰ (avg. 4.05 ‰, n = 16), and S isotopic values increase from the core (3.09 ‰, n = 3) to the middle (3.78 ‰, n = 11) to the edge (6.99 ‰, n = 2). These results illustrate mineral crystallization processes and the mixing between seawater-derived S and magmatic–hydrothermal fluids during the growth of the chimney. The zones from the edge to the core are characterized by crystal morphologies of colloform/anhedral pyrite to massive pyrite with decreasing δ34S values, revealing multi-stage mineral deposition and sulphur isotopic fractionation. In contrast to the increase in δ34S values from the core to the edge in one profile (profile A), anomalously low δ34S values in fine-grained pyrite relative to chalcopyrite in another profile (profile B) in the middle zone result from S isotopic exchange between seawater SO42− and fluid H2S due to different fluid–seawater mixing, possibly caused by variations in permeability and porosity across the chimney.

The 15.2°S hydrothermal field is located at 15.2°S, 13.4°W within the Mid-Atlantic Ridge (MAR) and was initially discovered during Cruise DY125-22 by the Chinese expedition during R/V Dayangyihao in 2011. Here, we provide detailed mineralogical, bulk geochemical, and Sr–Pb isotopic data for massive sulfides and basalts from the 15.2°S hydrothermal field to improve our understanding of the mineral compositions, geochemical characteristics, type of hydrothermal field, and the source of metals present at this vent site. The samples include 14 massive sulfides and a single basalt. The massive sulfides are dominated by pyrite with minor amounts of sphalerite and chalcopyrite, although a few samples also contain minor amounts of gordaite, a sulfate mineral. The sulfides have bulk compositions that contain low concentrations of Cu + Zn (mean 7.84 wt%), Co (mean 183 ppm), Ni (mean 3 ppm), and Ba (mean 16 ppm), similar to the Normal Mid-Ocean Ridge Basalt (N-MORB) type deposits along the MAR but different to the compositions of the Enriched-MORB (E-MORB) and ultramafic type deposits along this spreading ridge. Sulfides from the study area have Pb isotopic compositions (206Pb/204Pb = 18.4502–18.4538, 207Pb/204Pb = 15.4903–15.4936, 208Pb/204Pb = 37.8936–37.9176) that are similar to those of the basalt sample (206Pb/204Pb = 18.3381, 207Pb/204Pb = 15.5041, 208Pb/204Pb = 37.9411), indicating that the metals within the sulfides were derived from leaching of the surrounding basaltic rocks. The sulfides also have 87Sr/86Sr ratios (0.708200–0.709049) that are much higher than typical MAR hydrothermal fluids (0.7028–0.7046), suggesting that the hydrothermal fluids mixed with a significant amount of seawater during massive sulfide precipitation.

Significant Fe isotopic fractionation occurs during the precipitation and oxidative weathering of modern seafloor hydrothermal sulfides, which has an important impact on the cycling of Fe isotopes in the ocean. This study reports the Fe-isotope compositions of whole-rock sulfides and single-mineral pyrite collected from hydrothermal fields at the South Mid-Atlantic Ridge (SMAR) and the East Pacific Rise (EPR) and discusses the impacts of precipitation and late-stage oxidative weathering of sulfide minerals on Fe isotopic fractionation. The results show large variation in the Fe-isotope compositions of the sulfides from the different hydrothermal fields on the mid-oceanic ridges, indicating that relatively significant isotope fractionation occurs during the sulfide precipitation and oxidative weathering processes. The Fe-isotope compositions of the sulfides from the study area at the SMAR vary across a relatively small range, with an average value of 0.01‰. This Fe-isotope composition is similar to the Fe-isotope composition of mid-oceanic ridge basalt, which suggests that Fe was mainly leached from basalt. In contrast, the Fe-isotope composition of the sulfides from the study area at the EPR are significantly enriched in light Fe isotopes (average value − 1.63‰), mainly due to the kinetic fractionation during the rapid precipitation process of hydrothermal sulfide. In addition, the pyrite from different hydrothermal fields is enriched in light Fe isotopes, which is consistent with the phenomenon in which light Fe isotopes are preferentially enriched during the precipitation of pyrite. The red oxides have the heaviest Fe-isotope compositions (up to 0.80‰), indicating that heavy Fe isotopes are preferentially enriched in the oxidation product during the late-stage oxidation process. The data obtained from this study and previous studies show a significant difference between the Fe-isotope compositions of the sulfides from the SMAR and EPR. The relatively heavy Fe isotopes compositions of the sulfides from the SMAR may suggest the equilibrium fractionation process under high temperature conditions. The red Fe oxides are enriched in heavy Fe isotopes, indicating that the oxidative weathering processes result in the occurrence of significant Fe-isotope fractionation and the preferential enrichment of heavy Fe isotopes in the oxidation product.

Increasing threats to seamount ecosystems potentially from fishing and seabed mining are creating an urgent demand for research on megafauna to inform conservation and management. We surveyed the community structure of benthic megafauna on the Weijia Seamount, which is covered by cobalt-rich ferromanganese crusts, in the northwestern Pacific Ocean. A multidisciplinary dataset was generated from video recordings taken by a human occupied vehicle (HOV) and remotely operated vehicle (ROV) along transects and bathymetry-derived environmental variables. The spatial variation of community structure and its environmental and spatial factors impacting the community were then explored. A total of 2779 individuals of the megabenthos (from depths of 1533–2763 m, covering 24.4 km in distance and with a maximum of 109 individuals per 100 m by linear observation), was counted and classified into 76 morphospecies, which was dominated by crinoids, ophiuroids, hexactinellids and octocorals. Moderately abundant and diverse megafauna, high beta diversity and distinct assemblages were present in the Weijia Seamount, suggesting a highly patchy pattern within a single seamount. Six clusters of megafauna were revealed, with significant differences in species composition and biodiversity. The results of statistical analyses showed that the megafaunal community was impacted by at least eight environmental variables (latitude, depth, slope, curvature, rugosity, bathymetric position index, topography type, and substrate type), and excluding aspect. Among these variables, the topography and substrate types played key roles in the occurrence of small-scale aggregations of hexactinellids; depth-related variables were key factors, but no gradual depth-related change in terms of abundance, richness or species turnover was observed. This case study on the megabenthic community of the Weijia Seamount can serve as an environmental baseline, providing a reference status for seamount conservation and management.

The weathering processes of seafloor massive sulfide (SMS) deposits would significantly change the mineralogy and geochemistry of sulfides. The key to understanding the oxidation of SMS deposits lies in clarifying the metal mobilization during the oxidation of submarine sulfides by seawater and Fe-Si-rich hydrothermal fluids. We present the morphology, mineralogy, and geochemistry of secondary minerals and oxyhydroxides from the Xunmei hydrothermal field on the Southern Mid-Atlantic Ridge (SMAR) to illuminate their diverse characteristics and origins, further elaborating detailed submarine oxidation processes of sulfide mounds. Under the oxygenated seawater environments, the pyrite/marcasite and chalcopyrite were oxidized to Fe (oxyhydr)oxides and secondary Cu minerals (e.g., covellite, paratacamite/atacamite, and chalcanthite), respectively. The metal speciation in the sulfides (e.g., pyrite, marcasite, and chalcopyrite) controls the metal mobilization during oxidation. Cobalt and As in the crystal lattice of pyrite and marcasite vary over variations in Fe and S, respectively. Zinc, Ag, and Pb that occur as micron-inclusions in the pyrite, marcasite, and chalcopyrite are easily released during the galvanic interaction, of which mechanism is applicable to Cu-inclusions in the pyrite and marcasite. Compared to the enrichment of Zn and Ag in the secondary minerals via adsorption, Pb is depleted because of its high solubility in the seawater. The mineralization of amorphous oxyhydroxides includes low-temperature Si-rich precipitation and later oxidative weathering processes. The Si-rich hydrothermal fluids dissolve the basalt enriched in plagioclase and V-rich clay minerals to precipitate V-rich Si-Al oxyhydroxides. Subsequently, the flowing Si-rich hydrothermal fluids evoke precipitation of amorphous silica due to conductive cooling. As the alteration proceeds, a genetic scenario for the formation of Fe and Si oxyhydroxides is proposed. The Fe-Si-rich hydrothermal fluids alter the sulfides to Fe-Si oxyhydroxides and then Fe oxyhydroxides with an increasing trend of Fe, Cu, Zn, and Co. Our results unravel the metal mobilization during the weathering processes of submarine sulfides, establish a scenario for the formation of oxyhydroxides associated with sulfides, and predict the effect of oxidation on the economic values of sulfides.

Crustal assimilation and the input of subducted sediment in a subduction zone play vital roles in generating arc and back-arc lavas along a continental margin. However, distinguishing the impacts of these two processes on lava geochemistry is not straightforward or well understood. In this paper, we present new Hf–Nd–Sr–Pb isotopic data for 20 igneous rocks ranging in composition from basalt to rhyolite, which when combined with data from the literature allow us to fingerprint the contributions of crustal and slab-derived materials along the Okinawa Trough (OT). Consistent with previous results, the basaltic lavas were generated by melting of an Indian-type mantle source metasomatised by slab-derived fluids and subducted pelagic/detrital sediments. We confirm that Hf behaves as a non-conservative element during subduction, constrained by Hf-Nd isotopic systematics. Our new data suggest that crustal assimilation processes worked independently of the extent of magma differentiation but were determined by the stage of tectonic development in individual regions. In the southern OT (seafloor spreading stage), crustal assimilation is insignificant, and the addition of subducted sediment is 0.4%–1.5%. In the middle OT (crustal rifting stage), the basaltic and rhyolitic suites do not show distinctive Hf–Nd–Sr–Pb isotopic compositions, and both record moderate crustal assimilation (

Barley stripe mosaic virus (BSMV) Triple Gene Block1 (TGB1) is a multifunctional movement protein with RNA-binding, ATPase and helicase activities which mainly localizes to the plasmodesmata (PD) in infected cells. Here, we show that TGB1 localizes to the nucleus and the nucleolus, as well as the cytoplasm, and that TGB1 nuclear-cytoplasmic trafficking is required for BSMV cell-to-cell movement. Prediction analyses and laser scanning confocal microscopy (LSCM) experiments verified that TGB1 possesses a nucleolar localization signal (NoLS) (amino acids 95-104) and a nuclear localization signal (NLS) (amino acids 227-238). NoLS mutations reduced BSMV cell-to-cell movement significantly, whereas NLS mutations almost completely abolished movement. Furthermore, neither the NoLS nor NLS mutant viruses could infect Nicotiana benthamiana systemically, although the NoLS mutant virus was able to establish systemic infections of barley. Protein interaction experiments demonstrated that TGB1 interacts directly with the glycine-arginine-rich (GAR) domain of the nucleolar protein fibrillarin (Fib2). Moreover, in BSMV-infected cells, Fib2 accumulation increased by about 60%-70% and co-localized with TGB1 in the plasmodesmata. In addition, BSMV cell-to-cell movement in fib2 knockdown transgenic plants was reduced to less than one-third of that of non-transgenic plants. Fib2 also co-localized with both TGB1 and BSMV RNA, which are the main components of the ribonucleoprotein (RNP) movement complex. Collectively, these results show that TGB1-Fib2 interactions play a direct role in cell-to-cell movement, and we propose that Fib2 is hijacked by BSMV TGB1 to form a BSMV RNP which functions in cell-to-cell movement.

Significant Zn isotope fractionation occurs during seafloor hydrothermal activities. Therefore, exploring variations in Zn isotope composition affected by hydrothermal fluids and oxidative processes would help to better understand hydrothermal fluid cycling and sulfide deposition on mid-ocean ridges. In this paper, the Zn isotope compositions of different types of sulfides and their oxidation products obtained from hydrothermal fields on the South Mid-Atlantic Ridge (13–15°S) were analyzed using a Neptune plus MC-ICP-MS. The δ66Zn ratios range from –0.14‰ to +0.38‰, and the average δ66Zn ratio is +0.12±0.06‰ (n=21, 2 SD) for all the studied sulfides and oxidation products. The Cu-rich sulfides have a slightly heavier Zn isotope composition (average δ66Zn=+0.19±0.07‰, n=6) than the Zn-rich sulfides (average δ66Zn=–0.02±0.06‰, n=5). The Zn isotope compositions of the oxidation products are similar to those of the Cu-rich sulfides, with an average δ66Zn ratio of 0.14±0.06‰ (n=10, 2 SD). The Zn isotope compositions of all the samples are generally within the ranges of sulfides from hydrothermal fields on other mid-ocean ridges, such as the East Pacific Rise (9°N, 21°N) and the Trans-Atlantic Geotraverse. However, the average Zn isotope composition indicates the presence of significantly lighter Zn isotopes relative to those reported in the literature (average δ66Zn=+0.39‰). The significant enrichment of the Zn-rich sulfides with light Zn isotopes reveals that kinetic fractionation likely occurs during mineral deposition. Furthermore, the Zn isotope compositions of the sulfides and their oxidation products (average δ66Zn=+0.12‰) are significantly lighter than the average Zn isotope composition of the ocean (δ66Zn=+0.5‰), which could further constrain the modern Zn isotope cycle in the ocean by serving as a sink for light Zn isotopes.

Tomato leaf curl Guangdong virus (ToLCGdV) is a begomovirus associated with a Tomato yellow leaf curl disease (TYLCD) epidemic in Guangdong province, China. Being the least conserved protein among geminivirus proteins, the function of C4 during ToLCGdV infection has not been elucidated. In this study, the infectious clones of ToLCGdV and a ToLCGdV mutant (ToLCGdVmC4) with disrupted C4 ORF were constructed. Although ToLCGdV and ToLCGdVmC4 could infect Nicotiana benthamiana and tomato plants, ToLCGdVmC4 elicited much milder symptoms compared with ToLCGdV. To further verify the role of C4 in viral pathogenesis, C4 was expressed in N. benthamiana from Potato virus X (PVX) vector. The results showed that ToLCGdV C4 enhanced the pathogenicity of PVX and induced more severe developmental abnormalities in plants compared with PVX alone or PVX-mC4. In addition, ToLCGdV C4 suppresses systemic gene silencing in the transgenic N. benthamiana line 16c, but not local gene silencing induced by sense GFP in wild-type N. benthamiana plants. Moreover, C4 suppresses transcriptional gene silencing (TGS) by reducing the DNA methylation level of 35S promoter in 16c-TGS N. benthamiana plants. Furthermore, C4 could also interact with the receptor-like kinase (RLK) BARELY ANY MERISTEM 1 (BAM1), suggesting that C4 may suppress gene silencing by interfering with the function of BAM1 in the cell-to-cell spread of RNAi. All these results suggest that C4 is a pathogenic determinant of ToLCGdV, and C4 may suppress post-transcriptional gene silencing (PTGS) by interacting with BAM1.

Quaternary chalcogenide compound Cu2ZnSnS4 (CZTS) is a promising absorber material for low-cost thin film solar cells owing to the abundance of its constituents, suitable band-gap and high absorption coefficient. Conventionally, CZTS thin films are mainly fabricated using vacuum techniques including evaporation, sputtering and pulsed laser deposition. An encouraging power conversion efficiency of 8.4% has been achieved using vacuum deposition method. However, the vacuum deposition techniques are often associated with high energy input and thus impose a significant cost on the devices. Hence, there is a driving force towards replacing the vacuum deposition method with cost-effective processing techniques. I this thesis, I present the solution-based synthesis of CZTS nanoparticles and the deposition of CZTS thin films. CZTS nanoparticles were successfully synthesized using hot injection method. It was found that the reaction temperature plays an important role in determining the phase formation. At reaction temperature below 200°C, the binary Cu2-xS and ternary CTS form together with quarternary CZTS phases. At reaction temperature of 220 ºC and above, pure quaternary CZTS phase is favored. A detailed investigation of CZTS nanoparticles synthesized at 240°C shows that the nanoparticles have an average size of 19.8 nm and the average ratio of S, Cu, Zn and Sn was estimated to be 4.19: 1.96: 0.80: 1.05. In addition, the optical band gap of the CZTS nanoparticles was estimated to be 1.55 eV based on UV-vis-NIR absorption measurements. The reaction time greatly affects the nucleation and growth of nanoparticles. CZTS nanoparticles formed immediately after injection of S precursor. From 0 min to 30 min, the average size of the nanoparticles gradually increased and the size distribution became narrower. With longer reaction time, the growth of nanoparticles shows the phenomenon of Ostwald ripening. The size and shape of nanoparticles could be controlled through solvent-ligand optimization. With 1,2-dichlorobenzene (DCB) as the solvent and oleylamine (OLA) as the ligand, sub-micrometer size clusters (0 ml OLA), near-spherical shape (0.5 ml OLA), faceted (1 ml OLA), and nanoplates (2 ml OLA) CZTS nanostructures were synthesized. The sulfur precursor is the key parameter that determines the phase formation of CZTS polytypes. Kesterite CZTS were formed using elemental sulfur as the sulfur source, while wurtzite CZTS were produced using 1-dodecanthiol (DDT). The use of thioacetamide (TAA) resulted in the formation of mixture of kesterite and wurtzite phases. Further investigation revealed that the reaction rate of sulfur precursors plays a critical role. The elemental S could react with oleylamine to produce highly reactive small molecule H2S, which then precipitate with Cu, Zn and Sn species to form kesterite CZTS nanoparticles. As for the case of DDT, the covalent bonded S is very stable and difficult to be broken down to release S, leading to formation of wurtzite phase. TAA exhibit reaction rate between elemental S and DDT, therefore yields a mixture of kesterite and wurtzite pahses. The optical and electrical properties of kesterite and wurtzite were evaluated and showed similar properties. The optical band gaps of kesterite phase and wurtzite phase were estimated based on absorption measurements to be 1.48 eV and 1.55 eV respectively. The valance band and conduction band energy levels are determined using CV measurements to be -5.37 and -3.85 eV (kesterite), -5.60 and -3.91 eV (wurtzite). Compared with CZTS nanoparticles ink approach, a greener synthesis route based on CuS, ZnS and SnS2 nanoparticles with water or ethanol solvent was developed. The post-annealing plays an important role in the phase evolution from binary phases into quaternary CZTS phase. It was found that pure CZTS phase formed at 300°C, 400°C and 450°C. The selenization process was performed on the nanoparticles precursor film. CZTSSe thin film solar cells were fabricated following Mo/CZTSSe/CdS/ZnO/ITO/Au architecture. The as-fabricated device exhibited a total area efficiency of 5.12% with Voc of 378 mV, Jsc of 26.2 mA/cm2 and FF of 51.7%. These results are comparable with some of the best performing nanoparticles based CZTSSe solar cells. Combined with the low-cost, environmentally friendly and upscalable fabrication steps, our synthesis method is highly promising for potential industry scale application. DOCTOR OF PHILOSOPHY (MSE)

The nature of upper mantle is important to understand the evolution of the South China Sea (SCS), thus, we need better constrains on its mantle heterogeneity. Magma water concentration is a good indicator, but few data have been reported. However, the rarity of glass and melt inclusions and the special genesis for phenocrysts in SCS basalts present challenges to analyzing magmatic water content. Therefore, it is possible to estimate the water variations through the characteristics of partial melting and magma crystallization. We evaluated variations in Fe depletion, degree of melt fractions, and mantle source composition along the fossil spreading ridge (FSR) using SCS basalt data from published papers. We found that lava from the FSR 116.2° E, FSR 117.7° E, and non-FSR regions can be considered normal lava with normal water content, in contrast, lava from the FSR 117° E-carbonatite and 114.9–115.0° E basalts have higher water content and show evidence of strong Fe depletion during the fractional crystallization after elimination of the effects of plagioclase oversaturation. The enriched water in the 117° E-carbonatite basalts is contained in carbonated silicate melts, and that in the 114.9–115.0° E basalts results from mantle contamination with the lower continental crust. The lava from the 117° E-normal basalt has much lower water content because of the lesser influence of the Hainan plume. Therefore, there must be a mantle source compositional transition area between the southwestern and eastern sub-basins of the SCS, which have different mantle evolution histories. The mantle in the west is more affected by contamination with continental materials, while that in the east is more affected by the Hainan mantle plume.

Industrial manipulators are widely used in manufacturing process. With the help of off-line programming and CAM software, they are able to execute various processing tasks and ensure a high precision of the trajectory and processing effect. However, the capability of an industrial manipulator is constrained by many factors: the limitation on joint coordinates, the maximum speed of actuators, the range of output torques, etc. Kinematic or dynamic solutions without concern about these constraints may result in deviation from the planned joint trajectories and cause a crash in manipulation task through forward kinematics.In this paper, we solve the torque limitation control problem via Weighted-Least-Norm based method. An auxiliary variable is introduced to reformulate the control problem of torque limitation constrained manipulation task. Then the extended variable is solved by optimizing its weighted norm to keep the torque command for the planned joint acceleration in the actuators’ output ranges, which ensures a high precision trajectory tracking of the manipulator system.The validity of the algorithm is demonstrated by a mathematical proof, and a simulation of a PUMA-560 manipulator in the MATLAB ROBOTIC TOOLBOX. Comparison with the results generated by the null space torque optimization method and the existing weighted least norm method shows that the proposed method is more effective, accurate and stable and has superiority over these algorithms.