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| 1 | Carbon Isotope Gradient of the Ediacaran Cap Carbonate in the Shennongjia Area and Its Implications for Ocean Stratification and Palaeogeography显示文摘The geochemistry and paleogeography of the Doushantuo succession in the Shennongjia area have been insufficiently studied. Here, we report on the carbon and oxygen isotope compositions of Ediacaran Doushantuo cap carbonates from four sections(Longxi, Muyu, Yazikou and Songluo) in the Shennongjia area. A large C-isotopic gradient(~5‰) between the Longxi and Songluo sections, here identified for the first time, is inferred to have been dynamically maintained by photosynthesis in surface waters and anaerobic oxidation of dissolved organic carbon(DOC) in deep waters. Spatial variation in C-isotope chemostratigraphy among the four sections was related to Marinoan post-glacial sea-level elevation changes. At Longxi, a positive δ^(13)C_(carb) shift below the horizon containing tepee-like structure resulted from intense photosynthesis during early regression. A negative δ^(13)C_(carb) shift within the tepee-horizon was triggered by sulfate reduction and freshwater mixing with ^(13)C-depleted dissolved inorganic carbon(DIC) during late regression. A positive δ^(13)C_(carb) excursion in the uppermost part of the cap carbonate was related to enhance primary productivity and organic matter burial during early transgression. At Muyu, the carbon isotopic variation tendency, which is similar to that at Longxi, may have been mildly influenced by the surface water environment. At Songluo, the positive δ^(13)C_(carb) excursion, up to-4‰ in the lower part of the cap carbonate, was probably associated with methanogenesis in deep waters during late transgression to early regression and subsequently disappeared due to decomposition of methane hydrate during late regression. At Yazikou, the consistently stable δ^(13)C_(carb) values around-4‰ indicate that the cap carbonate may have deposited at intermediate water depths. As evidenced by diagnostic sedimentary characteristics of the study sections, the palaeogeographic framework of the Shennongjia area exhibited deepening from SE to NW during the Early Ediacaran Period in the aftermath of Snowball Earth. | Guangzhe Wang Jiasheng Wang Zhou Wang Can Chen Junxia Yang | 2017 | Journal of Earth Science2017，28，2： | 5 |
| 2 | Transferring deep neural networks for the differentiation of mammographic breast lesions显示文摘Machine learning can help differentiating benign and malignant lesions seen on mammographic images. Conventional models require handcrafting features for lesion representation. Due to insufficient medical instances, the performance of convolutional neural networks(CNNs) can be further increased. This study makes use of transfer learning for mammographic breast lesion diagnosis and deep neural network(DNN) models pre-trained with large-scale natural images are employed. The diagnosis performance is evaluated with the prediction accuracy(ACC) and the area under the curve(AUC) on average. A histologically verified database is analyzed which contains 406 lesions(230 benign and 176 malignant). Involved models include transferred DNNs(GoogLeNet and AlexNet), shallow CNNs(CNN2 and CNN3) that are fully trained with medical instances and boosted by support vector machine(SVM), and two conventional methods which combine handcrafted features and SVM for lesion diagnosis. Experimental results indicate that GoogLeNet achieves the best performance(ACC=0.81, AUC=0.88), followed by AlexNet(ACC=0.79, AUC=0.83) and CNN3(ACC=0.73, AUC=0.82). Knowledge transfer can improve the mammographic breast cancer diagnosis, while its wide application still requires further verification in medical imaging domain. | YU ShaoDe LIU LingLing WANG ZhaoYang DAI GuangZhe XIE YaoQin | 2019 | Science China(Technological Sciences)2019，62，3： | 5 |
| 3 | Quercetin promotes human epidermal stem cell proliferation through the estrogen receptor/β-catenin/c-Myc/cyclin A2 signaling pathway显示文摘Skin epidermal stem cells(EpSCs)play an important role in wound healing.Quercetin is a phytoestrogen reported to accelerate skin wound healing,but its effect on EpSCs is unknown.In this study,we investigated the effect of quercetin on human EpSC proliferation and explored the underlying mechanisms.We found that quercetin at 0.1~1μM significantly promoted EpSC proliferation and increased the number of cells in S phase.The pro-proliferative effect of quercetin on EpSCs was confirmed in cultured human skin tissue.Mechanistic studies showed that quercetin significantly upregulated the expressions ofβ-catenin,c-Myc,and cyclins A2 and E1.Inhibitor forβ-catenin or c-Myc significantly inhibited quercetin-induced EpSC proliferation.Theβ-catenin inhibitor XAV-939 suppressed quercetin-induced expressions ofβ-catenin,c-Myc,and cyclins A2 and E1.The c-Myc inhibitor 10058-F4 inhibited the upregulation of c-Myc and cyclin A2 by quercetin.Pretreatment of EpSCs with estrogen receptor(ER)antagonist ICI182780,but not the G protein-coupled ER1 antagonist G15,reversed quercetin-induced cell proliferation and upregulation ofβ-catenin,c-Myc,and cyclin A2.Collectively,these results indicate that quercetin promotes EpSC proliferation through ER-mediated activation ofβ-catenin/c-Myc/cyclinA2 signaling pathway and ER-independent upregulation of cyclin E1 and that quercetin may accelerate skin wound healing through promoting EpSC proliferation.As EpSCs are used not only in clinic to treat skin wounds but also as seed cells in skin tissue engineering,quercetin is a useful reagent to expand EpSCs for basic research,skin wound treatment,and skin tissue engineering. | Zhaodong Wang Guangliang Zhang Yingying Le Jihui Ju Ping Zhang Dapeng Wan Qiang Zhao Guangzhe Jin Hao Su Jinwei Liu Jiaxuan Feng Yi Fu Ruixing Hou | 2020 | Acta Biochimica et Biophysica Sinica2020，52，10： | 3 |
| 4 | Re–Os geochronology of the Cambrian stage-2 and-3 boundary in Zhijin County, Guizhou Province, China显示文摘The black shale series that formed in the Ediacaran–Cambrian transition are important stratigraphic records of the co-evolution of the paleo-ocean,-climate,and-biology. In this study, we measured Re–Os isotopic compositions of the black shale in the Niutitang Formation from the Gezhongwu section in Zhijin, Guizhou Province.The samples had high Re and Os contents, with Re ranging from 21.27 to 312.78 ng/g and Os ranging from 0.455 to7.789 ng/g. The Re–Os isotope isochron age of 522.9 ± 8.6 Ma implies deposition of the Niutitang black shale predated the Chengjiang Fauna, providing an age constraint for the expansion of oceanic anoxia in the study area. The initial ^(187)Os/^(188)Os ratio of 0.826 ± 0.026 indicates that enhanced continental weathering might have triggered the exansion of the oceanic anoxia. | Shuaichao Wei Yong Fu Houpeng Liang Zhihua Ge Wenxi Zhou Guangzhe Wang | 2018 | Acta Geochimica2018，37，2： | 3 |
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