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Now showing items 113 - 128 of 383

  • ChemInform Abstract: Direct Asymmetric Aldol Reaction of Cyclohexanone with Aldehydes Catalyzed by Chiral trans-Cyclohexanediamine L-Tartrate Salt.

    Shengying Wu   Limin Wang   Jun Tang   Dan Mao and Xin Liu  

    Optimum reaction conditions are examined.
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  • ChemInform Abstract: A Facile Synthesis of α-Aminophosphonates Catalyzed by Ytterbium Perfluorooctanoate under Solvent-Free Conditions.

    Jun Tang   Limin Wang   Wenbo Wang   Liang Zhang   Shengying Wu   Dan Mao  

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  • Improved degradation of organophosphate dichlorvos by Trichoderma atroviride transformants generated by restriction enzyme-mediated integration (REMI)

    Jun Tang   Lixing Liu   Shifeng Hu   Yunpeng Chen   Jie Chen  

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  • Modified Si–Jun–Zi–Tang Attenuates Airway Inflammation in a Murine Model of Chronic Asthma by Inhibiting Teff Cells via the mTORC1 Pathway

    Jin, Hualiang   Cai, Cui   Li, Bei   Jin, Weizhong   Xia, Junbo   Wang, Limin   Ma, Shenglin  

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  • Chinese Herbal Medicine Liu Jun Zi Tang and Xiang Sha Liu Jun Zi Tang for Functional Dyspepsia: Meta-Analysis of Randomized Controlled Trials

    Xiao, Ya   Liu, Yan-yan   Yu, Ke-qiang   Ouyang, Ming-zi   Luo, Ren   Zhao, Xiao-shan  

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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   Yongshu Xie  

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  • Metamaterials: Beyond Crystals, Noncrystals, and Quasicrystals Tie Jun Cui, Wen Xuan Tang, Xin Mi Yang, Zhong Lei Mei, and Wei Xiang Jiang

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  • Zircon SHRIMP U–Pb dating, C and O isotopes for impure marbles from the Jiaobei terrane in the Sulu orogen: Implication for tectonic affinity

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

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  • Extreme oxygen isotope signature of meteoric water in magmatic zircon from metagranite in the Sulu orogen, China: Implications for Neoproterozoic rift magmatism

    Jun Tang   Yong-Fei Zheng   Bing Gong   Yuan-Bao Wu   Tian-Shan Gao   Honglin Yuan   Fu-Yuan Wu  

    Unusual 18O depletion, with delta 18O values as negative as -10 0/ 00 to -4 0/ 00 relative to VSMOW, was reported in zircons from ultrahigh-pressure eclogite-facies metamorphic rocks in the Dabie-Sulu orogenic belt, China. But it is critical for the negative delta 18O zircons to be distinguished between magmatic and metamorphic origins, because the 18O depletion can be acquired by high-T eclogite-facies metamorphism of meteoric-hydrothermally altered low delta 18O rocks. While zircon O diffusion kinetics has placed a reasonable constraint on this, zircon trace element compositions can provide a straightforward distinction between the magmatic and metamorphic origins. This paper reports our finding of unusual 18O depletion in zircon from granitic gneiss in the northeastern end of the Sulu orogen. Zircon delta 18O values vary from -7.8 0/ 00 to -3.1 0/ 00 along a profile of 50 m length at Zaobuzhen. They are close to extremely low delta 18O values of -9.0 0/ 00 to -5.9 0/ 00 for metagranite at Qinglongshan and adjacent areas in the southwestern end of the Sulu orogen. CL imaging suggests that the low delta 18O zircons at Zaobuzhen are primarily of magmatic origin, but underwent different degrees of metamorphic modification. Zircon U-Pb dating yields middle Neoproterozoic ages of 751 plusmn 27 to 779 plusmn 25 Ma for protolith crystallization and Triassic ages of 214 plusmn 10 to 241 plusmn 33 Ma for metamorphic resetting. However, no metamorphic modification occurs in zircon REE patterns that only indicate magmatic recrystallization and hydrothermal alteration, respectively. Thus, the negative delta 18O zircons are interpreted as crystallizing from negative delta 18O magmas due to melting of meteoric-hydrothermally altered negative delta 18O rocks in an active rift setting at about 780 Ma. The variation in zircon delta 18O values indicates considerable O isotope heterogeneity in its granitic protolith. Zircon Lu-Hf isotope analyses give positive epsiv Hf(t) values of 1.6-4.1 and Hf model ages of 1.18-1.30 Ga. This suggests that the granitic protolith was derived from the mid-Neoproterozoic reworking of late Mesoproterozoic juvenile crust. The metagranites at Zaobuzhen and Qinglongshan, about 450 km apart, are two known occurrences of the unusually low delta 18O zircons below -6 0/ 00 so far reported in the Sulu orogen. They are similar to each other in both protolith and metamorphic ages, so that they share the same nature of both Neoproterozoic protolith and Triassic metamorphism. Therefore, the locally negative delta 18O zircons may register centers of low delta 18O magmatism during the supercontinental rifting.[All rights reserved Elsevier].
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  • Extreme oxygen isotope signature of meteoric water in magmatic zircon from metagranite in the Sulu orogen, China: Implications for Neoproterozoic rift magmatism

    Jun Tang   Yong-Fei Zheng   Bing Gong   Yuan-Bao Wu   Tian-Shan Gao   Honglin Yuan   Fu-Yuan Wu  

    Unusual 18O depletion, with δ18O values as negative as −10‰ to −4‰ relative to VSMOW, was reported in zircons from ultrahigh-pressure eclogite-facies metamorphic rocks in the Dabie-Sulu orogenic belt, China. But it is critical for the negative δ18O zircons to be distinguished between magmatic and metamorphic origins, because the 18O depletion can be acquired by high-T eclogite-facies metamorphism of meteoric-hydrothermally altered low δ18O rocks. While zircon O diffusion kinetics has placed a reasonable constraint on this, zircon trace element compositions can provide a straightforward distinction between the magmatic and metamorphic origins. This paper reports our finding of unusual 18O depletion in zircon from granitic gneiss in the northeastern end of the Sulu orogen. Zircon δ18O values vary from −7.8‰ to −3.1‰ along a profile of 50 m length at Zaobuzhen. They are close to extremely low δ18O values of −9.0‰ to −5.9‰ for metagranite at Qinglongshan and adjacent areas in the southwestern end of the Sulu orogen. CL imaging suggests that the low δ18O zircons at Zaobuzhen are primarily of magmatic origin, but underwent different degrees of metamorphic modification. Zircon U–Pb dating yields middle Neoproterozoic ages of 751 ± 27 to 779 ± 25 Ma for protolith crystallization and Triassic ages of 214 ± 10 to 241 ± 33 Ma for metamorphic resetting. However, no metamorphic modification occurs in zircon REE patterns that only indicate magmatic recrystallization and hydrothermal alteration, respectively. Thus, the negative δ18O zircons are interpreted as crystallizing from negative δ18O magmas due to melting of meteoric-hydrothermally altered negative δ18O rocks in an active rift setting at about 780 Ma. The variation in zircon δ18O values indicates considerable O isotope heterogeneity in its granitic protolith. Zircon Lu–Hf isotope analyses give positive εHf(t) values of 1.6–4.1 and Hf model ages of 1.18–1.30 Ga. This suggests that the granitic protolith was derived from the mid-Neoproterozoic reworking of late Mesoproterozoic juvenile crust. The metagranites at Zaobuzhen and Qinglongshan, about 450 km apart, are two known occurrences of the unusually low δ18O zircons below −6‰ so far reported in the Sulu orogen. They are similar to each other in both protolith and metamorphic ages, so that they share the same nature of both Neoproterozoic protolith and Triassic metamorphism. Therefore, the locally negative δ18O zircons may register centers of low δ18O magmatism during the supercontinental rifting.
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  • Zircon SHRIMP U–Pb dating, C and O isotopes for impure marbles from the Jiaobei terrane in the Sulu orogen: Implication for tectonic affinity

    Jun Tang   Yong-Fei Zheng   Yuan-Bao Wu and Bing Gong  

    Middle Neoproterozoic carbonates are found in the western part of Shandong Pennisula (i.e., the Jiaobei terrane) that is located in the northwestern part of the Sulu orogen in east-central China. For the first time, a successful SHRIMP U–Pb dating, coupled with CL imaging, was conducted on two samples of impure marble from the Fenzishan Group in this tectonic unit. The results yield consistent ages of 786 ± 67 and 240 ± 44 Ma for igneous and metamorphic zircons, respectively. Positive δ13C values as high as +5.6‰ are measured for both pure and impure marbles, consistent not only with the worldwide Neoproterozoic limestones in connection with the Sturtian ice-age, but also with the marbles associated with UHP metamorphic eclogites in the Dabie orogen. O isotope fractionation between calcite and garnet from one sample gave a temperature of 680 °C, pointing to upper amphibolite-facies metamorphic conditions. These results indicate that protolith of the marbles is a kind of limestone that was synchronously deposited with volcaniclastic rocks in the mid-Neoproterozoic rift basin of continental margin. Like the UHP metamorphic rocks in the Dabie-Sulu orogenic belt, both mid-Neoproterozoic magmatism and Triassic metamorphism are recorded in the impure marbles. Therefore, protolith of the impure marbles corresponds to the sedimentary limestone of rift basin developed during the mid-Neoproterozoic breakup of supercontinent Rodinia, but it was the sedimentary cover along the northern margin of the South China Block prior to its Triassic subduction. The occurrence of the mid-Neoproterozoic limestone with the Triassic metamorphism in the southern margin of the North China Block thus indicates tectonic overthrust by a crustal detachment between the sedimentary cover and the Precambrian basement during the continent subduction. As a result, the marbles in affinity to the South China Block were northward thrusted over the basement of the North China Block.
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  • Radiocolloid in Combination with Methylene Dye Localization, Rather Than Wire Localization, is a Preferred Procedure for Excisional Biopsy of Nonpalpable Breast Lesions

    Jun Tang   Xiao-Ming Xie   Xi Wang   Ze-Ming Xie   Jie-Hua He   Yao-Pan Wu   Wei Fan   Jian-Hua Fu   Ming-Tian Yang  

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  • Noggin and BMP4 co-modulate adult hippocampal neurogenesis in the APPswe/PS1ΔE9 transgenic mouse model of Alzheimer’s disease

    Jun Tang   Min Song   Yanyan Wang   Xiaotang Fan   Haiwei Xu   Yun Bai  

    In addition to the subventricular zone, the dentate gyrus of the hippocampus is one of the few brain regions in which neurogenesis continues into adulthood. Perturbation of neurogenesis can alter hippocampal function, and previous studies have shown that neurogenesis is dysregulated in Alzheimer disease (AD) brain. Bone morphogenetic protein-4 (BMP4) and its antagonist Noggin have been shown to play important roles both in embryonic development and in the adult nervous system, and may regulate hippocampal neurogenesis. Previous data indicated that increased expression of BMP4 mRNA within the dentate gyrus might contribute to decreased hippocampal cell proliferation in the APPswe/PS1ΔE9 mouse AD model. However, it is not known whether the BMP antagonist Noggin contributes to the regulation of neurogenesis. We therefore studied the relative expression levels and localization of BMP4 and its antagonist Noggin in the dentate gyrus and whether these correlated with changes in neurogenesis in 6–12 mo old APPswe/PS1ΔE9 transgenic mice. Bromodeoxyuridine (BrdU) was used to label proliferative cells. We report that decreased neurogenesis in the APP/PS1 transgenic mice was accompanied by increased expression of BMP4 and decreased expression of Noggin at both the mRNA and protein levels; statistical analysis showed that the number of proliferative cells at different ages correlated positively with Noggin expression and negatively with BMP4 expression. Intraventricular administration of a chimeric Noggin/Fc protein was used to block the action of endogenous BMP4; this resulted in a significant increase in the number of BrdU-labeled cells in dentate gyrus subgranular zone and hilus in APP/PS1 mice. These results suggest that BMP4 and Noggin co-modulate neurogenesis.
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  • Erratum to ‘p- and n-Type Ba8Ga16Ge30 studied by X-ray photoelectron spectroscopy’ [Chem. Phys. Lett. 472 (2009) 60]

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

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  • Evaluation of the teratogenic effects of three traditional Chinese medicines, Si Jun Zi Tang, Liu Jun Zi Tang and Shenling Baizhu San, during zebrafish pronephros development

    Ding Yu-Ju   Wang Bo-Cheng   Wen Chi-Chung   Sun Chiao-Yin   Lee Hsun-Hua   Lee Fei-Peng   Yang Ling-Ling   Chen Yau-Hung  

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  • Measurement of the rotation period of comet Hale-Bopp: TANG Yuan, QIAN Bo-chen, GU Ming-feng, TAO Jun & SONG Bao-jun Shanghai Observatory, CAS, Shanghai 200030

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