223 research outputs found

    Jiangnan Orogen, South China : a ~970–820 Ma Rodinia margin accretionary belt

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    Authors thank the Major State Research Development Program of China (Grant No. 2016YFC0600202) for financial support, as well as financial support from National Natural Science Foundation of China (Nos. 41330208, 41572200 and 41190070) and State Key Laboratory for Mineral Deposits Research (Nanjing University) (ZZKT–201603). Peter A. Cawood acknowledges support from Australian Research Council grant FL160100168.The Neoproterozoic Jiangnan Orogen in South China records a succession of arc-trench-basin assemblages culminating in accretion of the bounding Yangtze and Cathaysia blocks to form the stabilized South China Craton. The orogen can be traced over some 1500 km and extends up to 100 km across strike. It is divisible into three domains: the northeast domain (also referred to as the Huaiyu or Shuangxiwu Terrane), the central domain (Jiuling Terrane), and an undifferentiated southwest domain. The northeast domain contains arc type volcanic suites and I-type granitoids dated at ca. 970–850 Ma. It is interpreted as an intra–oceanic terrane based on the juvenile radiogenic isotopic signature of the igneous rocks, the absence of older detritus and inherited xenocrysts, and the presence of ophiolites along its southwestern and western margins. The central and southwest domains contain trench-arc-basin assemblages of clastic sedimentary units, mappable magmatic arc suites and ophiolitic mélanges (Sibao and equivalent groups) that range in age from ca. 880 to 820–815 Ma. The presence of old zircon grains within these two domains, both as detritus within sedimentary units and as inherited zircon in arc basalt, suggest they formed at convergent continental margins. S-type granites dated at 845–815 Ma are a distinctive element of the central and southwest domains. The ages of these granites overlap with convergent plate magmatism in the two domains, arguing against previous models for plume-rift and post-collisional geodynamic settings. Instead, these bodies likely formed in an accretionary orogenic margin setting in which granitic magmatism occurred in an extensional regime triggered by slab rollback. The slab-rollback process triggered mantle-sourced thermal input and partial melting of the older and buried arc-bounding basin sediments. Early Paleozoic S-type granites in the Lachlan and New England belts in eastern Australia and Jurassic ones in the Cordillera belt of the western US provide analogous geodynamic environments. Isotopic data indicate that the central Jiangnan domain experienced significant crustal growth, whereas in the southwest domain there was a greater degree of crustal reworking. The character and distribution of the early Neoproterozoic sedimentary and igneous succession in the orogen suggests it represents a ca. 970–820 Ma accretionary orogen. Upper age limits on the Jiangnan Orogen are provided by a regional angular unconformity in the central and southwest domains at ca. 810–805 Ma, and in the northeast domain at ca. 825 Ma, along with the overlying bimodal volcanic and clastic sedimentary successions mostly dated at ca. 810–730 Ma. Thus, timing of final assembly of South China displays variations across the Jiangnan Orogen, from ca. 825 Ma in the northeast to ca. 820–805 Ma in the central and southwest of the orogen. Post-assembly successions are parts of the Nanhua Basin and are interpreted to have formed during regional lithospheric extension across the eastern and central South China Craton. The age patterns across the South China Craton are indicative of northwest directed accretion of fragments and suggest an external rather than an internal position of the craton within the assembled Rodinia supercontinent. Paleomagnetic data, regional correlations and sedimentary records are consistent with a position along the northern margin of Rodinia, adjacent to India and Australia. The Jiangnan Orogen recorded the accretion of trench-arc assemblages and ultimately the Yangtze Block to the Cathaysia Block that was already located on the margin of Rodinia. The Panxi-Hanan belt, which lies along the western and northwestern margin of the Yangtze Block, formed on the upper plate to a subduction system that both overlaps with, and is younger than, the Jiangnan Orogen. The belt provides a record of ongoing accretion on the Rodinia margin until the mid-Neoproterozoic.PostprintPeer reviewe

    Ginsenosides are novel naturally-occurring aryl hydrocarbon receptor ligands.

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    The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor that mediates many of the biological and toxicological actions of structurally diverse chemicals. In this study, we examined the ability of a series of ginsenosides extracted from ginseng, a traditional Chinese medicine, to bind to and activate/inhibit the AHR and AHR signal transduction. Utilizing a combination of ligand and DNA binding assays, molecular docking and reporter gene analysis, we demonstrated the ability of selected ginsenosides to directly bind to and activate the guinea pig cytosolic AHR, and to stimulate/inhibit AHR-dependent luciferase gene expression in a recombinant guinea pig cell line. Comparative studies revealed significant species differences in the ability of ginsenosides to stimulate AHR-dependent gene expression in guinea pig, rat, mouse and human cell lines. Not only did selected ginsenosides preferentially activate the AHR from one species and not others, mouse cell line was also significantly less responsive to these chemicals than rat and guinea pig cell lines, but the endogenous gene CYP1A1 could still be inducted in mouse cell line. Overall, the ability of these compounds to stimulate AHR signal transduction demonstrated that these ginsenosides are a new class of naturally occurring AHR agonists

    Development of a Vacuum Ultra-Violet Laser-Based Angle-Resolved Photoemission System with a Super-High Energy Resolution Better Than 1 meV

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    The design and performance of the first vacuum ultra-violet (VUV) laser-based angle-resolved photoemission (ARPES) system are described. The VUV laser with a photon energy of 6.994 eV and bandwidth of 0.26 meV is achieved from the second harmonic generation using a novel non-linear optical crystal KBe2BO3F2 (KBBF). The new VUV laser-based ARPES system exhibits superior performance, including super-high energy resolution better than 1 meV, high momentum resolution, super-high photon flux and much enhanced bulk sensitivity, which are demonstrated from measurements on a typical Bi2Sr2CaCu2O8 high temperature superconductor. Issues and further development related to the VUV laser-based photoemission technique are discussed.Comment: 29 pages, 10 figures, submitted to Review of Scientific Instrument

    Estudo e Desenvolvimento de Uma Carga Eletronica Regenerativa, Baseada em Inversor Nao-Autonomo, Aplicada a...

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    Apresenta-se nesse estudo uma nova proposta de carga eletrônica regenerativa (CERE) para testes em equipamentos elétricos que permite que laboratórios de eletrônica de potência realizem ensaios com baixas perdas de energia; nesse caso, o fluxo de potência fornecida pelo equipamento em teste é dirigido quase que totalmente de volta para a rede elétrica, minimizando a dissipação de energia por efeito Joule, diferente do que acontece com o uso de resistores ou cargas eletrônicas convencionais. Do ponto de vista técnico, tais ensaios poderão ter suas características variadas segundo a necessidade de análise do equipamento sob teste, permitindo submetê-os a diferentes condições de funcionamento. O objetivo do protótipo da CERE-CA aqui desenvolvida é apenas comprovar os resultados teóricos e de simulação apresentados na dissertação. Neste primeiro momento, não haverá preocupação com a qualidade da energia que é regenerada para a rede CA, e nem com a precisão do controle do fluxo de corrente drenado da fonte CA. Estas e outras melhorias deverão ser implantadas em pesquisas futuras nessa área de eletrônica de potência

    Reconstructing South China in Phanerozoic and Precambrian supercontinents

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    This paper is financially supported by a NSFC Major Program (41190070) entitled “Reconstruction of East Asian Blocks in Pangea”. PAC acknowledges support from the Australian Research Council grant FL160100168 and WW thanks the support from “Thousand Youth Talents Plan”.The history of the South China Craton and the constituent Yangtze and Cathaysia blocks are directly linked to Earth's Phanerozoic and Precambrian record of supercontinent assembly and dispersal. Exposed Archean rocks are limited to isolated fragments in the Yangtze Block that preserve a record of Meso- to Neo-Archean magmatism, sedimentation and metamorphism associated with a period of global craton formation and stabilization that corresponds with the assembly of the Kenor supercontinent/supercraton. However, there are insufficient data to link its history with other similar aged cratons. The tectonostratigraphic record in South China in the Paleoproterozoic, corresponding with the assembly of Nuna, suggests that rock units in the Yangtze Block were spatially linked with northwestern Laurentia and possibly Siberia, whereas Cathaysia was joined to northern India. During the formation of Rodinia at the end of the Mesoproterozoic through to that of Pangea in the mid-Paleozoic, Cathaysia remained joined to northern India. Early Neoproterozoic supra-subduction zone magmatic arc-back arc assemblages ranging in age from ~ 1000 Ma to 810 Ma occur within Cathaysia, along its northwestern margin, and along the southeastern margin of the Yangtze Block. These rocks provide a record of convergent plate interaction, which continued along the western margin of the Yangtze Block until around 700 Ma and correlates with similar along strike subduction zone magmatism in northwest India, Seychelles and Madagascar. During the final assembly of Gondwana in the early Paleozoic suturing of India-South China with the Western Australia-Mawson blocks along the Kuunga Orogen resulted in the accretion of the Sanya Block of Hainan Island with the rest of Cathaysia. The accretion of Laurussia to Gondwana in the mid-Paleozoic to form Pangea corresponds with the initiation of lithospheric extension along the northern margin of Gondwana and the separation of a number of continental blocks, including South China, which then drifted northward across the Paleo-Tethys to collide with the Asian segment of Pangea in the Permo-Triassic.PostprintPeer reviewe

    Assessing the Pharmacological and Therapeutic Efficacy of Traditional Chinese Medicine Liangxue Tongyu Prescription for Intracerebral Hemorrhagic Stroke in Neurological Disease Models

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    Intracerebral hemorrhage is a fatal subtype of stroke, with crucial impact on public health. Surgical removal of the hematoma as an early-stage treatment for ICH can’t improve long-term prognosis remarkably. Liangxue tongyu prescription (LP), a Traditional Chinese Medicine (TCM) formula, includes eight ingredients and has been used to treat ICH in the clinical. In the study, we elucidated the pharmacological efficacy and therapeutic efficacy of LP to dissect the mechanism of LP against ICH via network analysis and experimental validation. First, we discovered 34 potential compounds and 146 corresponding targets in LP based on network prediction. 24 signal pathway were obtained by the Clue Go assay based on potential compounds in LP against ICH. Second, we found that LP can not only decreased the level of high sensitive C reactive protein (HS-CRP), tumor necrosis factor-α (TNF-α), NF-kβ, D-dimmer (D2D), estradiol (E2), S-100B, neuron specific enolase (NSE), and interleukin 1 (IL-1) in plasma on spontaneously hypertensive rats (SHRs), but also promoted cell proliferation and inhibited cell apoptosis on the glutamate-induced PC12 cell. The compounds including Taurine, Paeonol, and Ginsenoside Rb1 in LP can activate PI3K/AKT pathway. Third, from the three-factor two-level factorial design, compound combinations in LP, such as Taurine and Paeonol, Taurine and Geniposide, Ginsenoside Rg1, and Ginsenoside Rb1, had first-level interactions on cell proliferation. Compound combinations including Taurine and Paeonol, Ginsenoside Rg1 and Ginsenoside Rb1 had as significant increase in efficiency on inhibiting the apoptosis of PC12 cells at the low concentration and up-regulating of PI3K and AKT. Overall, our results suggested that LP had integrated therapeutic effect on ICH due to activities of anti-inflammatory, anti-coagulation, blood vessel protection, and protection neuron from excitotoxicity based on the way of “multi-component, multi-target, multi-pathway,” and compound combination in LP can offer protection neuron from excitotoxicity at the low concentration by activation of the PI3K/Akt signal pathway

    Diastereomers of the pentacoordinate chiral phosphorus compounds in solution: absolute configurations and predominant conformations

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    The absolute structural information about four sets of diastereomers of pentacoordinate spirophosphoranes, derived separately from L (or D)-phenylglycine and L (or D)-phenylalanine, has been obtained by using vibrational circular dichroism (VCD) spectroscopic measurements and density functional theory (DFT) for the first time. Each compound contains a stereogenic centre at the phosphorus center and two at the amino acid ligands. Geometric searches at the B3LYP/6-311++ G** level have been performed for all possible low energy conformers whose vibrational absorption (VA) and VCD spectra have also been simulated. The good agreement between the experimental VA and VCD spectra in the dimethyl sulfoxide (DMSO) solution and the simulated ones allows us to assign the absolute configurations and predominant conformations of these pentacoordinate phosphorus compounds with high confidence. Solvent effects have been examined by using both the experimental measurements and theoretical calculations. The implicit continuous polarization model and the explicit solute-solvent intermolecular hydrogen-bonding model have been considered to understand the effects of DMSO on the spectra observed. The influence of basis sets and different functionals on the VA and VCD spectra of this type of coordination compounds has also been investigated.University of Alberta ; Natural Sciences and Engineering Research Council of Canada ; Alberta Ingenuity ; NSFC [20732004, 20972130, 20773098]; Petro-Canad

    Cattle Mammary Bioreactor Generated by a Novel Procedure of Transgenic Cloning for Large-Scale Production of Functional Human Lactoferrin

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    Large-scale production of biopharmaceuticals by current bioreactor techniques is limited by low transgenic efficiency and low expression of foreign proteins. In general, a bacterial artificial chromosome (BAC) harboring most regulatory elements is capable of overcoming the limitations, but transferring BAC into donor cells is difficult. We describe here the use of cattle mammary bioreactor to produce functional recombinant human lactoferrin (rhLF) by a novel procedure of transgenic cloning, which employs microinjection to generate transgenic somatic cells as donor cells. Bovine fibroblast cells were co-microinjected for the first time with a 150-kb BAC carrying the human lactoferrin gene and a marker gene. The resulting transfection efficiency of up to 15.79×10−2 percent was notably higher than that of electroporation and lipofection. Following somatic cell nuclear transfer, we obtained two transgenic cows that secreted rhLF at high levels, 2.5 g/l and 3.4 g/l, respectively. The rhLF had a similar pattern of glycosylation and proteolytic susceptibility as the natural human counterpart. Biochemical analysis revealed that the iron-binding and releasing properties of rhLF were identical to that of native hLF. Importantly, an antibacterial experiment further demonstrated that rhLF was functional. Our results indicate that co-microinjection with a BAC and a marker gene into donor cells for somatic cell cloning indeed improves transgenic efficiency. Moreover, the cattle mammary bioreactors generated with this novel procedure produce functional rhLF on an industrial scale
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