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Now showing items 97 - 108 of 108

  • Caledonian reworking of Paleoproterozoic basement in the Cathaysia Block: Constraints from zircon U-Pb dating, Hf isotopes and trace elements

    Zeng Wen   Zhang Li   Zhou HanWen   Zhong ZengQiu   Xiang Hua   Liu Rui   Jin Song   Lue XinQian   Li ChunZhong  

    A combined study of zircon U-Pb dating, Hf isotopes and trace elements has been carried out for granodioritic neosomes of migmatites from the Tianjingping area in northwestern Fujian Province. Zircons are characterized by zoning, higher Th/U ratios (mostly >= 0.1), HREE enrichment, and positive Ce and negative Eu anomalies, and show features similar to magmatic or anatectic zircons. Apparent Pb-206/U-238 ages for the zircons are 447 +/- 2 Ma (95% conf., MSWD = 0.88), corresponding to a Caledonian event. epsilon(Hf)(t) values are -13.3 to -9.7, indicating a crustal source. Two-stage Hf model ages are 1.7 to 1.9 Ga, suggesting that protolith of the migmates was probably formed in the Paleoproterozoic. The granodioritic neosomes have the characteristics of peraluminous calc-alkaline granite, and their REE patterns and trace elements spidergrams show features of middle to upper crustal rocks. Together with previous studies, we conclude that the protolith of the Cathaysia basement in the Tianjingping area was likely formed in the middle-late Paleoproterozoic and experienced partial melting during the Caledonian period. The recognition of Caledonian reworking of the Paleoproterozoic basement in the Cathaysia Block provides a new insight into the tectonic evolution of the Cathaysia Block in the Caledonian period and the interaction between the Cathaysia Block and the Yangtze Block.
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  • Exploration of nano-surface chemistry for spectral analysis

    LI ChengHui   LIU Rui   Lü Yi   HOU XianDeng   WU Peng  

    The applications of nano-surface chemistry in the field of spectral analysis have attracted growing interest in recent years.In this article,we reviewed the applications of nanomaterials-based chemical reactions for spectral analysis,including the development in plasma-catalysis,surface-enhanced spectroscopy,separation and preconcentration,chemical vapor generation,labeling and signal amplification.Introduction of nano-surface chemistry to spectral analysis not only improves the sensitivity and selectivity,broadens the application range of spectral analysis,but also affords analytical community special characterization tools.
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  • Protective Effects of Luteolin against Amyloid beta(25-35)-induced Toxicity on Rat Cerebral Microvascular Endothelial Cells

    Liu Rui   Lan Xi   Ying Jian  

    AIM: To evaluate the effects of luteolin against amyloid beta-peptide 25-35 (A beta(25-35)) on rat cerebral microvascular endothelial cells (CMECs). METHODS: CMECs were isolated from Wistar rats at 3-week-old, and randomly divided into 5 groups including control group, A beta(25-35) group, 0.1, 1.0, and 10.0 mu mol.L-1 luteolin groups. Cell viability was determined with MTS assay. Intracelluar ROS level and SOD activity were monitored by DCFH-DA and SOD inhibition assay, respectively. Transendothelial electrical resistance was measured using an EVOM resistance meter. gamma-Glutamyl transpeptidase and alkaline phosphatase activities were detected using activity assay kits. Levels of TXA(2) and PGI(2) in culture medium were measured as their stable metabolites, TXB2 and 6-keto-PGF(1 alpha), by ELISA. RESULTS: Luteolin attenuated A beta(25-35)-induced toxicity at 0.1, 1.0, and 10 mu mol.L-1, inhibited intracellular ROS generation, and increased SOD activity at 1.0 and 10 mu mol.L-1. Luteolin was also found to preserve CMECs barrier function, involving the alleviation of TEER reduction, the increase of characteristic enzymatic activity, and regulation of TXA(2) and PGI(2) secretion. CONCLUSION: Luteolin had the ability to protect rat CMECs against A beta(25-35)-induced toxicity.
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  • U-Pb zircon geochronology and Hf isotope study of metamorphosed basic-ultrabasic rocks from metamorphic basement in southwestern Zhejiang: The response of the Cathaysia Block to Indosinian orogenic event

    Xiang Hua   Zhang Li   Zhou HanWen   Zhong ZengQiu   Zeng Wen   Liu Rui   Jin Song  

    A combined study using LA-ICP-MS U-Pb dating, Hf isotopes, trace elements and the Ti-in-zircon geothermometer was carried out on zircons from the metamorphosed basic-ultrabasic rocks in the metamorphic basement of the Cathaysia Block, southwestern Zhejiang Province. The formation and metamorphic ages of the rocks from the metamorphic basement of the Cathaysia Block were determined based on zircon U-Pb geochronology. The age for the magmatic crystalline zircons from the protolith is about 1.85 Ga. The epsilon (Hf) (t) values of the older zircons were from -7 to -3, with two-stage model Hf ages (T(DM2)(LC)) of about 2.9 to 3.4 Ga, indicating that the source material was derived from anatexis and recycling of the Archean crust. The newly formed metamorphic zircons yielded U-Pb ages of 260-230 Ma. The metamorphic temperature calculated using the Ti-in-zircon geothermometer ranged from 610 to 720 degrees C, consistent with the results from petrographic observations, indicating that the Cathaysia Block experienced an amphibolite facies metamorphism during the Indosinian. Results from this study provided an important timeframe for the tectonic evolution in South China and the Southeast Asia during the Late Permian and Early Triassic times.
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  • Enhanced Efficiency of Dye-sensitized Solar Cells Using rGO@TiO2 Nanotube Hybrids

    Liu Rui   Qiao Yingjie   Song Yingjin   Song Kehan   Liu Chuan  

    We established a novel strategy for the synthesis of reduced graphene oxide(rGO)@TiO2 nanotube hybrids using an 18 W UV-assisted photo-catalytic reduction method for utilization as photo-anode of dye-sensitized solar cells(DSSCs). The photo-conversion efficiency of DSSCs was significantly enhanced after the addition of rGO, and in addition, the photo-anode showed decreased internal resistance. Analysis of rGO@TiO2 hybrids by transmissions scanning electron microscopy(TEM), X-ray diffraction(XRD), Raman spectra, N-2 adsorption and desorption, atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS) demonstrates that the rGO modified TiO2 nanotubes can increase the short-circuit current and the conversion efficiency of dye-sensitized solar cells. The efficiency is improved by almost two folds as much compared to those of the bare TiO2 nanotubes.
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  • Antimicrobial metabolites from the endophytic fungus Aspergillus sp. of Eucommia ulmoides.

    Zhang HongChi   Liu Rui   Zhou Feng   Wang RunMei   Liu XiaoCui   Zhang HangTao  

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  • Application of chemical vapor generation in ICP-MS:A review

    GAO Ying   LIU Rui   YANG Lu  

    Chemical vapor generation(CVG) is an important sample introduction technique,and is widely used for atomic spectrometry for its enhanced sensitivity and selectivity.In the past 30 years,inductively coupled plasma mass spectrometry(ICP-MS) has become a widely used and the most sensitive instrument for(ultra-)trace element determination and elemental speciation.A review of applications of this state-of-the-art coupling of CVG and ICP-MS is presented.Discussion is focused on its applications for both element determination and speciation,including hydride generation,cold vapor generation,photochemical vapor generation,alkylation,and electrochemical vapor generation.In addition,recent studies undertaken isotope dilution calibration in CVG-ICPMS for achieving improved accuracy and precision are summarized,and the future perspectives are discussed.
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  • An Algorithm for Estimating Fundamental Matrix Based on Removing the Exceptional Points

    Liu Rui   Wang Feng  

    In this paper, an algorithm for estimating fundamental matrix based on removing the exceptional points is proposed. It uses normalized 8-point algorithm to estimate the initial value of the fundamental matrix, and then refines it by eliminating the exceptional points. Furthermore, the Genetic Algorithm(GA) is used to optimize the initial fundamental matrix by minimizing the Sampson error. Experiment results show that our algorithm is quite correct and reasonable for estimating the fundamental matrix.
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  • Walkability Assessment of Microclimatic Environments of Six Typical Communities in Central Urban Area of Beijing from the Perspective of the Elderly

    YANG Xin   LIU Rui  

    Community walking space is the most used space in residents’ daily life, such as commuting and walking, and is also the most basic type of space for outdoor activities. The microclimatic environment of walking space not only affects the health status of residents, but also determines the service efficiency of outdoor public space. Based on actual measurement and simulation of microclimatic environment, the status quo of walkability of microclimatic environments in six typical communities is evaluated by quantitative methods, and general problems and optimization suggestions are put forward, in order to provide new ideas for future community environment transformation.
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  • Morphological control of zinc tricarbohydrazide perchlorate crystals: Theoretical and experimental study

    Liu Rui   Qi ShuYuan   Zhang TongLai   Zhou ZunNing   Yang Li   Zhang JianGuo  

    The theoretical crystal-morphology of zinc tricarbohydrazide perchlorate (ZnCP) was studied using the morphology simulation software. The growth trends and surface characteristics were calculated using the Bravais-Friedel-Donnay- Harker (BFDH), Growth Morphology, and Equilibrium Morphology methods; these provide theoretical guidance for the choice of crystal-control reagents. On the basis of the simulations, experiments were carried out to study the effects of five different crystal-control reagents, including carboxymethylcellulose (A), polyacrylamide (B), dextrin (C), Tween 40 (D), and Tween 60 (E), in the control of the crystal-morphology of ZnCP. Mixtures of two reagents and higher temperatures were used to further optimize the ZnCP crystals. The results show that ZnCP crystals are well dispersed, and have a large apparent density and regular crystal-morphology under the control of a mixture of reagents A and E in a mass ratio of 1:4 at 80 degrees C.
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  • Variability of organic carbon isotope and C/N in the Hemudu Area,Hangzhou Bay and its environmental implications in the Holocene

    Liu Rui   Zheng Hongbo  

    With the purpose of tracing the variations of the organic matter sources of sediments, a sample column (25.96 m in size) from the Hemudu Area of Hangzhou Bay was put through AMS(14)C dating and biogeochemical analysis. TOC and TN presented similar variation trends, suggesting the same and stable sources of organic matter; the bad correlation between the grain size and TOC content indicated that the organic matter occurrence was neither controlled by the grain size nor the surface absorption of the fine particles, but it may has something to do with the complicated sedimentary hydrodynamic force, the input of organic matter and microbial action. Judging on the basis of C/N ratio and delta C-13(TOC), the organic carbon in sediments was a mixture of terrigenous and marine organic carbon, testifying to the land-sea interaction characteristic of the study area. The indexes experienced abrupt changes at about 6.5 ka BP, when the lighter terrigenous organic carbon made an increased proportion to the heavier marine organic carbon. The phenomenon reflected the enclosure of the lagoon and the reduced exchange interactions with the seawater of open seas.
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  • UV photolysis for accelerated quinoline biodegradation and mineralization.

    Yan Ning   Chang Ling   Gan Lu   Zhang YongMing   Liu Rui   Rittmann, B. E.  

    Sequentially and intimately coupled photolysis with biodegradation were evaluated for their ability to accelerate quinoline-removal and quinoline-mineralization kinetics. UV photolysis sequentially coupled to biodegradation significantly improved biomass-growth kinetics, which could be represented well by the Aiba self-inhibition model: UV photolysis increased the maximum specific growth rate ( max) by 15%, and the inhibition constant ( KSI) doubled. An internal loop photo-biodegradation reactor (ILPBR) was used to realize intimately coupled photolysis with biodegradation. The ILPBR was operated with batch experiments following three protocols: photolysis alone (P), biodegradation alone (B), and intimately coupled photolysis and biodegradation (P&B). For P&B, the maximum quinoline removal rate ( rmax) increased by 9%, KSI increased by 17%, and the half-maximum-rate concentration ( KS) decreased by 55%, compared to B; the composite result was a doubling of the quinoline-biodegradation rate for most of the concentration range tested. The degree of mineralization was increased by both forms of photolysis coupled to biodegradation, and the impact was greater for intimate coupling (18% increase) than sequential coupling (5%). The benefits of UV photolysis were greater with intimate coupling than with sequential coupling due to parallel transformation by biodegradation and photolysis.
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