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        Preparation of modified graphene oxide/polyethyleneimine film with enhanced hydrogen barrier properties by reactive layer-by-layer self-assembly

        Li, Peng,Chen, Kuo,Zhao, Lili,Zhang, Hongyu,Sun, Haixiang,Yang, Xiujie,Kim, Nam Hoon,Lee, Joong Hee,Niu, Q. Jason Elsevier Science Ltd 2019 Composites Part B, Engineering Vol.166 No.-

        <P><B>Abstract</B></P> <P>Hydrogen barrier properties are characteristic of polymeric materials prepared with graphene; thus, they can be considered as a good substitute for the metal body of the traditional hydrogen storage tank. Graphene oxide/polymer layer-by-layer self-assembling film based on noncovalent force shows good hydrogen gas barrier properties. However, the dense film structure can be broken when the film is placed in water environment, especially acidic or alkaline environment, which induces to the leak of the hydrogen gas. Herein, a modified graphene oxide/polyethyleneimine reactive layer-by-layer self-assembled film for the hydrogen barrier was fabricated by the covalent bond self-assembled technology. Graphene oxide was modified with ethylene glycol diglycidyl ether to introduce epoxy groups that can react with polyethyleneimine to form covalent bonds. The modification time, modification pH value, and the feed ratio of graphene oxide/ethylene glycol diglycidyl ether were investigated in detail. Results indicate that the self-assembled films were prepared by covalent bonds between polyethyleneimine and modified graphene oxide. When the modification time was 6 h, pH value was 2, and the feed ratio of graphene oxide/ethylene glycol diglycidyl ether was 0.05/0.23, the hydrogen transmission rate of 10-bilayer modified graphene oxide/polyethyleneimine self-assembled films was 289 cm<SUP>3</SUP>/m<SUP>2</SUP>·24 h·0.1 MPa, which was decreased by 78.8% compared to that of the polyethylene terephthalate substrate films (1365 cm<SUP>3</SUP>/m<SUP>2</SUP>·24 h·0.1 MPa). Furthermore, the modified graphene oxide/polyethyleneimine reactive layer-by-layer self-assembled films exhibit acid-resistance, alkali-resistance, salt-resistance and thermal-resistance properties.</P>

      • SCIESCOPUSKCI등재

        Compound K attenuates hyperglycemia by enhancing glucagon-like peptide-1 secretion through activating TGR5 via the remodeling of gut microbiota and bile acid metabolism

        Tian, Fengyuan,Huang, Shuo,Xu, Wangda,Chen, Lan,Su, Jianming,Ni, Haixiang,Feng, Xiaohong,Chen, Jie,Wang, Xi,Huang, Qi The Korean Society of Ginseng 2022 Journal of Ginseng Research Vol.46 No.6

        Background: Incretin impairment, characterized by insufficient secretion of L-cell-derived glucagon-like peptide-1 (GLP-1), is a defining step of type 2 diabetes mellitus (T2DM). Ginsenoside compound K (CK) can stimulate GLP-1 secretion; however, the potential mechanism underlying this effect has not been established. Methods: CK (40 mg/kg) was administered orally to male db/db mice for 4 weeks. The body weight, oral glucose tolerance, GLP-1 secretion, gut microbiota sequencing, bile acid (BA) profiles, and BA synthesis markers of each subject were then analyzed. Moreover, TGR5 expression was evaluated by immunoblotting and immunofluorescence, and L-cell lineage markers involved in L-cell abundance were analyzed. Results: CK ameliorated obesity and impaired glucose tolerance in db/db mice by altering the gut microbiota, especially Ruminococcaceae family, and this changed microbe was positively correlated with secondary BA synthesis. Additionally, CK treatment resulted in the up-regulation of CYP7B1 and CYP27A1 and the down-regulation of CYP8B1, thereby shifting BA biosynthesis from the classical pathway to the alternative pathway. CK altered the BA pool by mainly increasing LCA and DCA. Furthermore, CK induced L-cell number expansion leading to enhanced GLP-1 release through TGR5 activation. These increases were supported by the upregulation of genes governing GLP-1 secretion and L-cell differentiation. Conclusions: The results indicate that CK improves glucose homeostasis by increasing L-cell numbers, which enhances GLP-1 release through a mechanism partially mediated by the gut microbiota-BA-TGR5 pathway. Therefore, that therapeutic attempts with CK might be useful for patients with T2DM.

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        Photocatalytic degradation of dyes using dioxygen activated by supported metallophthalocyanine under visible light irradiation

        Yuyuan Yao,Zhenfu Huang,Binbin Zheng,Shun Zhu,Wangyang Lu,Wenxing Chen,Haixiang Chen 한국물리학회 2013 Current Applied Physics Vol.13 No.8

        Zinc tetraaminophthalocyanine (Zn-TAPc) modified by cyanuric chloride was immobilized on silk fibers by covalent bond to obtain a supported photocatalyst (Zn-TDTAPc-SF). The photocatalytic degradation of acid orange II based on Zn-TDTAPc-SF/O2 system was investigated under visible light irradiation (λ ≥ 400 nm). The results indicated that Zn-TDTAPc-SF exhibited excellent photocatalytic performance in the presence of O2 under visible light irradiation. In 6 h, more than 93% of acid orange II (AO2) in Zn-TDTAPc-SF/O2 systemwas eliminated at initial pH 5 under visible light irradiation, and Zn-TDTAPc-SF still remained effective in repetitive fives cycles. Furthermore, NaCl played a positive role in the catalytic reaction, different from the negative one observed in homogeneous catalysis, and the reaction can proceed in a more wide pH range from acidic to alkaline. Based on the analysis of FT-IR and Gas Chromatography/Mass Spectrometry (GCeMS), AO2 was mainly converted into some small molecular biodegradable aliphatic carboxylic compounds such as maleic acid, fumaric acid, succinic acid, etc. The photodegradation mechanism for the evolution of AO2 was proposed by Electron Paramagnetic Resonance (EPR) spectra.

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