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Search Results: 1 - 10 of 4777 matches for " Yueming Duan "
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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.
The Spatial Distribution Pattern Analysis of City Infrastructure Cases of Urban Management  [PDF]
Jiwei Hou, Jianhua Liu, Siyu Li, Shiran Song, Congcong Li, Yueming Duan, Baoshan Zeng
Journal of Geoscience and Environment Protection (GEP) , 2018, DOI: 10.4236/gep.2018.612002
Abstract: The effective disposal of daily city infrastructure cases is an important issue for urban management. To more effectively utilize a large amount of historical cases data collected and accumulated in the urban grid management system, and to analyze their spatial distribution pattern information for city managers, this study used the comparative kernel density analysis method in two types of cases (i.e. power facilities and traffic guardrail) in Xicheng District, Beijing for the year 2016 and 2017. This research analyzes them at different scales (300 m, 600 m, 1,200 m), and the experiment results show that the method of comparative kernel density analysis is able to provide an intuitively spatial visualization distribution analysis of city infrastructure related cases. The quantitative information of spatial agglomeration degree is helpful for city managers making decision.
Polyphenolic Profile and Antioxidant Activities of Oolong Tea Infusion under Various Steeping Conditions
Xinguo Su,Jun Duan,Yueming Jiang,Xuewu Duan,Feng Chen
International Journal of Molecular Sciences , 2007, DOI: 10.3390/i8121196
Abstract: The phenolic profile and antioxidant activities of oolong tea extract wereinvestigated after tea was steeped in 90 or 100 oC water for 3 or 10 min. The extractionyield increased with increasing temperature and extended steeping time. However, highertemperature and longer time (100 oC water for 10 min) led to loss of phenolics. Theaqueous extract of oolong tea (AEOT) at 100 oC for 3 min exhibited the strongestantioxidant activity. The major polyphenolic components of the AEOT were identified as(-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin-3-gallate (ECG). The two major catechins (EGC and EGCG) in the tea infusion contributedsignificantly to the investigated antioxidant activities [i.e., the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging and superoxide radical scavengingactivities] with high correlation values in r = 0.9486 and 0.9327 for the EGC and r =0.9592 and 0.8718 for the EGCG, respectively.
Analysis of Geographical Distribution of Missing Children Based on the Missing Children Mobile GIS Mutual Assistance System of China  [PDF]
Xiaodong Gong, Hao Cheng, Lu Yang, Yueming Duan, Yuan Yao, Yafei Feng, Le Fu, Jianhua Liu, Mingyi Du
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.512009
Abstract: The Missing Children Mobile GIS Mutual Assistance System of China (MCMAS) is a mobile service software based on mobile GIS platform software, and it is committed to providing the most convenient and efficient system of personally mutual tracing services for missing children family and society. Relying on collaborative utilization of location-based service technology, face image intelligent recognition technology, cloud computing technology, public big data sharing technology, and mobile GIS technology, the MCMAS has achieved prominent application effects since it was deployed. At present, the MCMAS is running soundly, and it has received and released the information about 1011 missing children from May 25, 2016 to May 25, 2017. In order to explore the geographical distribution features and the influencing factors of missing children, the data of missing children are used for spatial and visual analysis by the data mining and GIS technologies. At the same time, we have built the spatial thermodynamic diagram of the big data of China missing children. By comparing provinces and cities with a higher proportion of missing children, the results showed that: 1) The high proportion of missing children spatially concentrated in the eastern part of the China. 2) The number of missing children was significantly correlated with the population density and economic status of the city. Furthermore, the paper macro-levelly presents a basic basis for rescuing the missing children from two aspects: regionally spatial characteristics and influencing factors.
Quantitative Study of Lunisolar Precession Mechanism  [PDF]
Yueming Wu, Mingfu Cao
Journal of Geoscience and Environment Protection (GEP) , 2016, DOI: 10.4236/gep.2016.47021
According to Xiaodong Song et al.’s study about difference rotation in the Earth’s inner core, a physical model of lunar motion changing the angular momentum of the Earth’s circles is presented in this work. The Lunar motion makes there be a huge gap existing in the core angular momentum between far lunar hemisphere and near lunar hemisphere. The gap results in the difference rota-tion in the Earth’s inner core, meanwhile, it increases the angular velocity of far lunar hemisphere and decreases the angular velocity of near lunar hemisphere. The Earth’s liquid outer core gene-rates an astro-geodynamical effect including the difference rotation among the Earth’s circles. It is found that when the moon moves into the apogee or the perigee of the lunar orbit, and the moon phase is the upper and lower chords (i.e. semi-diameter place), the true anomaly of the moon will change from 270-degree back (or forward) to 90-degree; this results in the mantle shell of the Earth westward, and forms lunisolar precession, the vernal equinox westward and Chandler polar motion.
Effects of Various Temperatures and pH Values on the Extraction Yield of Phenolics from Litchi Fruit Pericarp Tissue and the Antioxidant Activity of the Extracted Anthocyanins
Neungnapa Ruenroengklin,Jia Zhong,Xuewu Duan,Bao Yang,Jianrong Li,Yueming Jiang
International Journal of Molecular Sciences , 2008, DOI: 10.3390/ijms9071333
Abstract: Litchi fruit pericarp tissue is considered an important source of dietary phenolics. This study consisted of two experiments. The first was conducted to examine the effects of various extraction temperatures (30, 40, 50, 60, 70 and 80 °C) and pH values (2, 3, 4, 5 and 6) on the extraction yield of phenolics from litchi fruit pericarp. Extraction was most efficient at pH 4.0, while an extraction temperature of 60 °C was the best in terms of the combined extraction yield of phenolics and the stability of the extracted litchi anthocyanins. The second experiment was carried out to further evaluate the effects of various temperatures (25, 35, 45, 55 and 65 °C) and pH values (1, 3, 5 and 7) on the total antioxidant ability and scavenging activities of DPPH radicals, hydroxyl radical and superoxide anion of the extracted anthocyanins. The results indicated that use of 45?60 °C or pH 3?4 exhibited a relatively high antioxidant activity. The study will help improve extraction yield of phenolics from litchi fruit pericarp and promote better utilization of the extracted litchi anthocyanins as antioxidants.
Identificationof Major Phenolic Compounds of Chinese Water Chestnut and their Antioxidant Activity
Yanli You,Xuewu Duan,Xiaoyi Wei,Xinguo Su,Mouming Zhao,Jian Sun,Neungnapa Ruenroengklin,Yueming Jiang
Molecules , 2007, DOI: 10.3390/12040842
Abstract: Chinese water chestnut (CWC) is one of the most popular foods among Asian people due to its special taste and medical function. Experiments were conducted to test the antioxidant activity and then determine the major phenolic compound components present in CWC. CWC phenolic extract strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against α,α-diphenyl-β-picrylhydrazyl (DPPH) radicals, superoxide anions and hydroxyl radicals, which was superior to ascorbic acid and butylated hydroxytoluene (BHT), two commercial used antioxidants. Furthermore, the CWC extract was found to have a relatively higher reducing power, compared with BHT. The major phenolic compounds present in CWC tissues were extracted, purified and identified by high-performance liquid chromatograph (HPLC) as (–)-gallocatechin gallate, (–)-epicatechin gallate and (+)-catechin gallate. This study suggests that CWC tissues exhibit great potential for antioxidant activity and may be useful for their nutritional and medicinal functions.
Enhanced DPPH radical scavenging activity and DNA protection effect of litchi pericarp extract by Aspergillus awamori bioconversion
Sen Lin, Bao Yang, Feng Chen, Guoxiang Jiang, Qing Li, Xuewu Duan, Yueming Jiang
Chemistry Central Journal , 2012, DOI: 10.1186/1752-153x-6-108
Abstract: The study exhibited that the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities significantly (p?<?0.05) increased from 15.53% to 18.23% in the water-extracted fraction and from 25.41% to 36.82% in the ethyl acetate-extracted fraction. Application of DNA cleavage assay further demonstrated the enhanced protection effect of the fermented phenolics on DNA damage. It is also noted that the water-extracted fraction of the fermented LPE possessed a much stronger capacity than the ethyl acetate-extracted fraction to prevent from damage of supercoiled DNA. Interestingly, it was found that some new compounds such as catechin and quercetin appeared after of A. awamori fermentation of LPE, which could account for the enhanced antioxidant activity.The DPPH radical scavenging activity and DNA protection effect of LPE were increased by Aspergillus awamori bioconversion while some compounds responsible for the enhanced antioxidant activity were identified. This study provided an effective way of utilizing fruit pericarp as a readily accessible source of the natural antioxidants in food industry and, thus, extended the application area such as fruit by-products.Phenolic compounds as secondary metabolites are widely present in fruits and vegetables. A positive relationship between consumption of food with abundant phenolics and low incidence of degenerative diseases, including cancer, heart disease, inflammation, arthritis, brain dysfunction and cataracts, has been confirmed [1]. Litchi (Litchi chinensis Sonn.) is a subtropical fruit with a brightly red pericarp which contains a significant amount of phenolics such as epicatechin, procyanidins, cyanidin-3-glucoside, and quercetin-3-rutinoside [2]. These phenolics exhibit good antioxidant ability [3], and anticancer and immunomodulatory activities [4].Currently, biotransformation of plant byproducts by microorganisms is one of an effective means to produce bioactive compounds. Many fruit byproducts, such as grape pomace, pi
Gamma-secretase: from pathogenesis to therapeutics
Li Yueming
Molecular Neurodegeneration , 2012, DOI: 10.1186/1750-1326-7-s1-l4
A Simple Analysis Method of Products lifetime Distribution
Yueming Wang
Modern Applied Science , 2009, DOI: 10.5539/mas.v3n3p38
Abstract: The basis of reliability analysis is determining products lifetime distribution type, which is also a tedious job. In accordance with the failure of parametric estimation using probability papers and hypothetical examination, products lifetime distribution type is studied with linear regression analysis and Office Excel.
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