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Search Results: 1 - 10 of 43968 matches for " Wu Genfu "
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Evaluation of the Antioxidant Properties of Litchi Fruit Phenolics in Relation to Pericarp Browning Prevention
Xuewu Duan,Genfu Wu,Yueming Jiang
Molecules , 2007, DOI: 10.3390/12040759
Abstract: Phenolics were extracted from litchi fruit pericarp (LFP) tissues, purified and their antioxidant properties analyzed. LFP phenolics strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against α,α-diphenyl-β-picrylhydrazyl (DPPH·) and hydroxyl radicals and superoxide anions. The degradation of deoxyribose by hydroxyl radicals was inhibited by phenolics acting mainly as iron ion chelators, rather than by directly scavenging the radicals. Phenolics from litchi fruit pericarp were found to display similar reducing power activity as ascorbic acid. The effect of phenolic compound treatment on pericarp browning and electrolyte leakage of litchi fruit was also evaluated and it was observed that application of exogenous litchi phenolics to harvested litchi fruit significantly prevented pericarp browning and delayed increases in electrolyte leakage. These results suggest that litchi pericarp tissue phenolics could be beneficial in scavenging free radicals, maintaining membrane integrity and, thereby inhibiting pericarp browning of litchi fruit.

Wu Genfu,

微生物学报 , 2001,
Abstract: The DPPH free-radical scavengers from the fungal Chinese medicine 'Wulingshen' (Xylaria nigripes) were studied. After separation using silica gel colunm chromatography, MPLC and HPLC, 20 DPPH free-radical scavengers with purity higher than 85% and yield more than 2 mg were screened, in which compound B4-16 had relatively higher yield and stronger free radical scavenging activity. The formula of compound B4-16 was determined to be C10H10O4 (MW: 194) based on its FAB-MS, 1H-NMR, 13C-NMR, 1H-13C HMBC, IR spectra, and its structure was elucidated. It was identical with 5,8-dihydroxy-3-methyl-3,4-dihydroisocoumarin. At the concentration of 20 mumol/L, its DPPH free\|radical scavenging activity was as 1.67 times as that of vitamin C or 2.10 times as that of Vitamin E.

Wu Genfu,Wu Xuechang,

微生物学报 , 2000,
Abstract: A strain belongs to Monascus sp. was separated from hongqu(Chinese beni-coji) which was used to brew red wine in Changxin county, Zhejiang province, and its DPPH radical scavenging metabolites were studied. Results showed that the yield and radical scavenging activity of neutral extract with EtOAc were higher than that of acid and basic extract. After shaken at 30 degrees C, 100 r/min for 5 days, this strain produced largest amount of neutral extract. Further partitioning the neutral fraction with silica gel column chromatograph, LH-20 column chromatograph, MPLC and HPLC, we screened 15 free radical scavengers whose yield was more than 2 mg and purity was higher than 85% in HPLC (260 nm absorption). Several of them were analyzed with 1H-NMR and 13C-NMR spectrum from which we concluded that B1-3 and C3-1-7 were two kinds of substitute of benzene, and C3-1-7 may be 3-OH-4-OCH3-benzoic acid. The scavenging activity of 40 mumol/L B1-3 was about 65%, and that of C3-1-7 was lower than 56%, while as the control the scavenging activity of 40 mumol/L Vc and Ve was 80.4% and 78.4% respectively.

WU Genfu,XUAN Xiaodong,WANG Fusan,

生态学报 , 1999,
Abstract: The population distribution of microorganisms in the water body of West Lake was studied from Apr.1995 to Apr.1996.Results showed that:(1) The density of heterotrophic bacteria were 2 06×10 3/ml on the average.Actinomycetes,molds and yeasts were 35/ml,24/ml and 2/ml respectively.(2)The coliform index in the Xili and Yuehu L.were 23 800/L,and those in the other sub lakes were lower.(3)Various physiological groups of microbes were found in West Lake,including cellulose decomposing bacte...

Wu Genfu,Chen Peihua,

微生物学通报 , 1994,
Abstract: This article introduced a simple method of seperating , cultivating and observingmicroorganism. It can be used for aerobe and aerotolerant anaerobe. The results showed thismethod has many adventages:(1) suits for doing research on individual growth of microorganismconsecutively;(2) can test death percentage of microorganism fast and simply;(3)suits forobtaining pure strain from mixed microorganisms effectively;(4) supplies a convenient methodfor the research of aerotolerant anaerobe.
Unique Organizational and Functional Features of the Cytochrome c Maturation System in Shewanella oneidensis
Miao Jin, Yaoming Jiang, Linlin Sun, Jianhua Yin, Huihui Fu, Genfu Wu, Haichun Gao
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075610
Abstract: Shewanella are renowned for their ability to respire on a wide range of electron acceptors, which has been partially accredited to the presence of a large number of the c-type cytochromes. In the model species S. oneidensis MR-1, at least 41 genes encode c-type cytochromes that are predicted to be intact, thereby likely functional. Previously, in-frame deletion mutants for 36 of these genes were obtained and characterized. In this study, first we completed the construction of an entire set of c-type cytochrome mutants utilizing a newly developed att-based mutagenesis approach, which is more effective and efficient than the approach used previously by circumventing the conventional cloning. Second, we investigated the cytochrome c maturation (Ccm) system in S. oneidensis. There are two loci predicted to encode components of the Ccm system, SO0259-SO0269 and SO0476-SO0478. The former is proven essential for cytochrome c maturation whereas the latter is dispensable. Unlike the single operon organization observed in other γ-proteobacteria, genes at the SO0259-SO0269 locus are uniquely organized into four operons, ccmABCDE, scyA, SO0265, and ccmFGH-SO0269. Functional analysis revealed that the SO0265 gene rather than the scyA and SO0269 genes are relevant to cytochrome c maturation.
Factors restricting growth of heterotrophic bacteria in the water body of West Lake, Hangzhou

WU Genfu,YANG Zhijian,ZHOU Xueping,WU Jie,

应用生态学报 , 2003,
Abstract: Restricting factors of bacteria growth were studied by pure culture and natural culture test. The results showed that organic carbon source available for bacteria was more important than (NH4)2SO4 and KH2PO4, while higher pH, and rich biomass of phytoplanktons and zooplanktons in the water restrained the growth of heterotrophic bacteria. Under natural culture experiment, Azotobacter increased after 0.5% glucose was added, and a lot of mildew grew after adding 0.5% glucose with 0.1% (NH4)2SO4 and 0.1% KH2PO4, while Pseudomonas enriched 30-57% after adding 0.01% beef extract. It was also showed that bacteria growth potentiality in natural water could reach to 10(5) cfu.ml-1.
Physical origin of superconductivity in EuFe2As1.4P0.6 and EuFe2As2: pressure-induce valence change of europium
Liling Sun,Jing Guo,Genfu Chen,Xianhui Chen,Xiaoli Dong,Wei Lu,Chao Zhang,Zheng Jiang,Bo Zou,Yuying Huang,Qi Wu,Xi Dai,Zhongxian Zhao
Physics , 2010,
Abstract: Superconductivity can be realized in Eu-containing pnictides by application of chemical (internal) and physical (external) pressure, the intrinsic physical mechanism of which attracts much attention in physics community. Here we present the experimental evidence for the valence change of europium in compounds of EuFe2As1.4P0.6 exposed to ambient pressure and EuFe2As2 to high pressure by x-ray absorption measurements on L3-Eu edge. We find that the absorption spectrum of EuFe2As1.4P0.6 at ambient pressure shows clear spectra weight transfer from a divalent to a trivalent state. Furthermore, application of pressure on EuFe2As2 using a diamond anvil cell shows a similar behavior of valence transition as EuFe2As1.4P0.6. These findings are the first observation of superconductivity mechanized by valence change in pnictides superconductors and elucidate the intrinsic physical origin of superconductivity in EuFe2As1.4P0.6 and compressed EuFe2As2.
Correlation between intercalated magnetic layers and superconductivity in pressurized EuFe2(As0.81P0.19)2
Jing Guo,Qi Wu,Ji Feng,Genfu Chen,Tomoko Kagayama,Chao Zhang,Wei Yi,Yanchun Li,Xiaodong Li,Jing Liu,Zheng Jiang,Xiangjun Wei,Yuying Huang,Katsuya Shimizhu,Liling Sun,Zhongxian Zhao
Physics , 2010, DOI: 10.1209/0295-5075/111/57007
Abstract: We report comprehensive high pressure studies on correlation between intercalated magnetic layers and superconductivity in EuFe2(As0.81P0.19)2 single crystal through in-situ high pressure resistance, specific heat, X-ray diffraction and X-ray absorption measurements. We find that an unconfirmed magnetic order of the intercalated layers coexists with superconductivity in a narrow pressure range 0-0.5GPa, and then it converts to a ferromagnetic (FM) order at pressure above 0.5 GPa, where its superconductivity is absent. The obtained temperature-pressure phase diagram clearly demonstrates that the unconfirmed magnetic order can emerge from the superconducting state. In stark contrast, the superconductivity cannot develop from the FM state that is evolved from the unconfirmed magnetic state. High pressure X-ray absorption (XAS) measurements reveal that the pressure-induced enhancement of Eu's mean valence plays an important role in suppressing the superconductivity and tuning the transition from the unconfirmed magnetic state to a FM state. The unusual interplay among valence state of Eu ions, magnetism and superconductivity under pressure may shed new light on understanding the role of the intercalated magnetic layers in Fe-based superconductors.
Reemerging superconductivity at 48 K across quantum criticality in iron chalcogenides
Liling Sun,Xiao-Jia Chen,Jing Guo,Peiwen Gao,Hangdong Wang,Minghu Fang,Xiaolong Chen,Genfu Chen,Qi Wu,Chao Zhang,Dachun Gu,Xiaoli Dong,Ke Yang,Aiguo Li,Xi Dai,Ho-kwang Mao,Zhongxian Zhao
Physics , 2011, DOI: 10.1038/nature10813
Abstract: Pressure plays an essential role in the induction1 and control2,3 of superconductivity in iron-based superconductors. Substitution of a smaller rare-earth ion for the bigger one to simulate the pressure effects has surprisingly raised the superconducting transition temperature Tc to the record high 55 K in these materials4,5. However, Tc always goes down after passing through a maximum at some pressure and the superconductivity eventually tends to disappear at sufficiently high pressures1-3. Here we show that the superconductivity can reemerge with a much higher Tc after its destruction upon compression from the ambient-condition value of around 31 K in newly discovered iron chalcogenide superconductors. We find that in the second superconducting phase the maximum Tc is as high as 48.7 K for K0.8Fe1.70Se2 and 48 K for (Tl0.6Rb0.4)Fe1.67Se2, setting the new Tc record in chalcogenide superconductors. The presence of the second superconducting phase is proposed to be related to pressure-induced quantum criticality. Our findings point to the potential route to the further achievement of high-Tc superconductivity in iron-based and other superconductors.
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