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Now showing items 97 - 112 of 383

  • Zircon U–Pb age and geochemical constraints on the tectonic affinity of the Jiaodong terrane in the Sulu orogen, China

    Jun Tang   Yong-Fei Zheng   Yuan-Bao Wu   Bing Gong   Xiangping Zha    Xiaoming Liu  

    Because of tectonic mixture by subduction erosion during Triassic continental collision between the North and South China Blocks, identifying the tectonic affinity of the Jiaodong terrane in the Sulu orogen is a key to recognition of the suture location in east-central China. In this study, zircon U–Pb ages, whole-rock major and trace elements as well as Rb–Sr and Sm–Nd isotopes, and mineral O isotopes were determined for ultrahigh-pressure (UHP) granitic gneiss and enclosed eclogite in the Jiaodong terrane, a petrotectonic unit southeast of the Wulian-Yantai fault. The granitic gneiss is characterized mostly by: (1) the presence of major Neoproterozoic igneous zircons and minor Triassic metamorphic zircons, which yielded the U–Pb ages of 741 ± 6 Ma interpreted as the emplacement age of the protoliths and 234 ± 5 Ma as the time of UHP metamorphism, respectively; (2) negative Nd(t) values of −7.4 to −3.8 at t = 750 Ma with Nd model ages of 1.73–2.03 Ga; and (3) low δ18O zircons of −0.4 to 4.1‰. Zircons from the eclogite also yield concordant metamorphic ages ranging from 229 ± 3 to 239 ± 7 Ma, with low δ18O values of 0.2–5.1‰. Thus, both granitic gneiss and eclogites share the same 18O depletion in their Neoproterozoic protoliths and experienced the same metamorphic event in the Triassic. Zircon U–Pb ages of 1866 ± 34 to 2057 ± 31 Ma were obtained for a few samples, consistent with the presence of Paleoproterozoic crust in the South China Block. In particular, the widespread occurrence of Neoproterozoic igneous protoliths with low δ18O values is evident in this region, with an outcrop area of over 10,000 km2. Such Neoproterozoic igneous rocks with low δ18O are not found in the North China Block, but are considered to be characteristic products of Neoproterozoic rift magmatism along the northern margin of the South China Block. Therefore, the protoliths of UHP metamorphic rocks in the Jiaodong terrane have a tectonic affinity to the South China Block, like those rocks elsewhere along the Dabie–Sulu orogenic belt. Their petrogenesis is explained by the plate-rift model within the framework of tectonic evolution from supercontinental rift to breakup during the middle Neoproterozoic. Despite crustal detachment and tectonic accretion during the Triassic continental collision, the presence of 1.8–2.0 Ga protoliths in the UHP metamorphic zone does not mean that these lithotectonic slices were derived from the continental margin of the North China Block.
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  • Geochronology and geochemistry of metamorphic rocks in the Jiaobei terrane: Constraints on its tectonic affinity in the Sulu orogen

    Jun Tang   Yong-Fei Zheng   Yuan-Bao Wu   Bing Gong   Xiaoming Liu  

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  • Probing the microenvironment of an oligo-(p-phenylene vinylene) derivative encapsulated in polymer-impregnated sol-gel silica matrix

    Jun Tang   Chuang Du   Xiaoqiang Yu   Guo Zhang   Ce Wang  

    Polymer-impregnated silica sol-gel composite materials are hosts for organics in advanced optics application. An oligo-phenylene vinylene derivative 4,4′-(1,4-phenylene dithenylene)-bis-(N-methyl pyridinium iodide) (OPVD) was introduced to poly(hydroxyethyl methacrylate) (PHEMA)-impregnated silica composite film by the sol-gel process. By comparing the X-ray diffraction, UV-visible spectra, steady-state and time-resolved fluorescence spectra of OPVD in three solid matrices (PHEMA/silica composite film, pure PHEMA film, and pure silica film), the similar results of PHEMA/silica composite film and pure PHEMA film demonstrate that the OPVD is primarily surrounded by a PHEMA-like environment in the composite matrix. The model of such structure is presented, which is useful for further understanding and optimizing of properties of doped sol-gel materials.
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  • p- and n-Type Ba8Ga16Ge30 studied by X-ray photoelectron spectroscopy

    Jun Tang   Ryotaro Kumashiro   Jing Ju   Zhaofei Li   Marcos A. Avila   Kouichirou Suekuni   Toshiro Takabatake   Fangzhun Guo   Keisuke Kobayashi   Katsumi Tanigaki  

    The electronic properties of p- and n-type Ba8Ga16Ge30 (BGG) are studied using soft X-ray photoelectron spectroscopy at a high-energy facility. Three bands are resolved in the valence band region. The first band for n-type BGG is sensitive to temperature, while the second band is sensitive for p-type BGG. The change in the ratio of Ba to Ga, from which the carrier type is controlled in this system, modifies the positions of Ga residing at the larger (Ga–CGe)24 cage. This modification in the host network is responsible for the large differences observed in electronic properties of p- and n-BGGs in this clathrate family.
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  • ChemInform Abstract: Ytterbium Pentafluorobenzoate as a Novel Fluorous Lewis Acid Catalyst in the Synthesis of 2,4-Disubstituted Quinolines.

    Jun Tang   Limin Wang   Dan Mao   Wenbo Wang   Liang Zhang   Shengying Wu and Yongshu Xie  

    A series of air-stable and water-tolerated rare earth metal pentafluorobenzoates are prepared for the first time.
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  • Identification of mucilage cavity as a significant microscopic characteristic existing in phloem instead of pith of Radix et Rhizoma Rhei

    Jun Tang   Yibin Feng   Yao Tong   Ruirui Jia   Laiking Sy   R. Y. K. Man  

    The morphologic and microscopic features of Radix et Rhizoma Rhei were studied. The study verified that the mucilage cavities did exist in phloem of rhizomes and roots or abnormal vascular bundles. Also, they were in similar distribution in three species of Radix et Rhizoma Rhei. The diagnostic characteristic for microscopic identification was found to be the similar distribution of abnormal vascular bundles in pith of rhizomes in all three species. And the appearance of the crude drug varied more depending on the plants’ geographical origin and different preliminary treatment on the spot of collection than on the species differences. Our findings, having not been delineated clearly so far in the previous reports, are helpful for clarifying current descriptions in different literatures or standards and make a full understanding on microscopic and macroscopic identification of Radix et Rhizoma Rhei.
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  • Substituted anilinopyrazoles

    The present invention relates to anilinopyrazole derivatives, methods for the preparation of such anilinopyrazoles, and use of such anilinopyrazoles in the treatment of certain diseases or conditions. In particular, the present invention relates to a nilinopyrazole derivatives useful as CDK2 inhibitors and use of the anilinopyrazoles in the treatment of disorders mediated by inappropriate CDK2 activity.
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  • Chemical compounds

    3-carboxy quinoline derivatives, which are useful as YAK3 inhibitors are described herein. The described invention also includes methods of making such 3-carboxy quinoline derivatives as well as methods of using the same in the treatment of diseases mediated by inappropriate YAK3 activity.
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  • Chemical compounds

    This invention relates to newly identified compounds for inhibiting hYAK3 proteins and methods for treating diseases associated with the imbalance or inappropriate activity of hYAK3 proteins.
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  • Anilinopyrazole as Selective CDK2 Inhibitors: Design, Synthesis, Biological Evaluation, and X-Ray Crystallographic Analysis.

    Jun Tang   Lisa M. Shewchuk   Hideyuki Sato   Masaichi Hasegawa   Yoshiaki Washio   Naohiko Nishigaki  

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  • Low expression of ULK1 is associated with operable breast cancer progression and is an adverse prognostic marker of survival for patients

    Jun Tang   Rong Deng   Rong-Zhen Luo   Guo-Ping Shen   Mu-Yan Cai   Zi-Ming Du   Shan Jiang   Ming-Tian Yang   Jian-Hua Fu   Xiao-Feng Zhu  

    ULK1 plays an important role in autophagy which is widely involved in the development of breast cancer. However, the function and expression of ULK1 in human breast cancer is still scarcely explored. In this study, we showed that the mRNA and protein levels of ULK1 decreased in 10 of 14 (71.4 %) breast cancer tissues, compared with matched normal tissues. Furthermore, immunohistochemical staining of ULK1 was performed on the tissue microarray containing 298 non-metastatic invasive breast primary cancer tissues and 73 matched adjacent noncancerous tissues. 70.1 % breast cancer specimens displayed none to weak staining of ULK1, however, 78.1 % adjacent noncancerous specimens showed moderate to strong staining of ULK1. Statistical analysis revealed that ULK1 expression was negatively correlated with tumor size (r = -0.176, P = 0.002), lymph node status (r = -0.115, P = 0.048), and pathological stage (r = -0.177, P = 0.002). The log-rank test showed that patients with lower level of ULK1 had a significant shorter distant metastasis-free survival time (P = 0.008) and cancer-related survival time (P = 0.008). Multivariate Cox regression analysis found that ULK1 expression was recognized as an independent prognostic factor (P = 0.034). In addition, a significant positive correlation between expression of ULK1 and LC3A (r = 0.401, P < 0.001), and a significant negative correlation between expression of ULK1 and p62 (r = -0.226, P < 0.001) were observed in our breast cancer cohort. These findings suggest that decreased expression of ULK1 is associated with breast cancer progression, together with closely related to decreased autophagic capacity. ULK1 also may be used as a novel prognostic biomarker for breast cancer patients.
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  • ChemInform Abstract: One-Pot Synthesis of 2-Amino-3-cyanopyridine Derivatives Catalyzed by Ytterbium Perfluorooctanoate [Yb(PFO)3]

    Jun Tang   Limin Wang   Yinfang Yao   Liang Zhang   Wenbo Wang  

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  • Layer-by-layer self-assembled multilayer film of cationic oligo-(phenylene vinylene) and polyelectrolytes based on electrostatic interaction

    Jun Tang   Wen Jiang Li   Ying Wang   Bo Wang   Jingzhi Sun   Bai Yang  

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  • ChemInform Abstract: A New Strategy for the Preparation of an Active Mn(0) and Its Use for Radical Cyclization Reactions.

    Jun Tang   Hiroshi Shinokubo   Koichiro Oshima  

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