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Photolysis of mono- through deca-chlorinated biphenyls by ultraviolet irradiation in n-hexane and quantitative structure-property relationship analysis

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Journal of Environmental Sciences 2008年第6期20卷 753-759页

作者： LI xue FANg Lei HUANg Jun YU gang POPs Research Centre Department of Environmental Science and Engineering Tsinghua University Beijing 100084 China

The photolysis of 16 polychlorinated biphenyls （PCBs）（including mono- through deca-chlorinated） in n-hexane was investigated under ultraviolet irradiation using a 500-W high-pressure mercury lamp. Photolysis of PCBs follows pseudo-first-order reaction kinetics, with photolysis rate constants ranging between 0.0011 s^-1 for PCB-52 and 0.0574 s^-1 for PCB-118. The degradation rates of PCBs by high-pressure mercury lamp irradiation were remarkably independent with respect to the degree of chlorination. Furthermore, partial least squares （PLS） models were developed to provide insight into which aspect of the molecular structure influenced PCB photolysis rate constants. It was found that the photolysis rates of PCBs increased with an increase in the net charge on the carbon atom （qc）, （ELUMO-EHOMO）^2, and the Y-axis dipole moment （μy） values, or the decrease in the energy of the second highest occupied molecular orbital （EHOMO-1）, energy of the lowest unoccupied molecular orbital （ELUMO）, ELUMO ＋ EHOMO, ELUMO - EHOMO, most positive atomic charge （q^＋）, and the twist angle of the chlorine atom （TA） values.

关键词： Photolysis polychlorinated biphenyls n-hexane partial least squares quantum chemical descriptors

Critical environmental factors affecting mountain geohazards in a warming climate in Southwest China

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Advances in Climate Change Research 2024年第4期15卷 695-707页

作者： Xiao-Ming XU Peng CUI xue-qin ZHANg Key Lab of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 10010lChina University of Chinese Academy of Sciences Beijing 100049China China-Pakistan Joint Research Center on Earth Sciences Chinese Academy of Sciences and Higher Education CommissionIslamabad 45320Pakistan

Environmental factors are essential input variables for susceptibility assessment models of mountain ***,the existing literature provides a limited understanding of the relative contribution of these factors to the occurrence of geohazards with a warming climate,posing tremendous challenges for risk management in mountainous ***'an city is susceptible to hazards because of its steep terrain,abundant precipitation and active seismic *** this regard,we utilise the geoDetector model to extract critical environmental factors affecting the spatial patterns of mountain geohazards(i.e.,landslide,debris flow and rockfall)in Southwest *** analysis indicates that the factors with the highest explanatory power for the spatial distribution of landslides,debris flows,and rockfalls are soil property,extreme precipitation and extreme temperature,***,we revealed the synergistic effects among factors given their larger q-value than individual *** further explored the responses of mountain geohazards to climate change,including the rising temperature and precipitation,because the frequent occurrence of mountain geohazards is closely related to a warming *** variation in snow water equivalent caused by antecedent snowfall and snowdrifts acts as a crucial indicator for geohazards,highlighting the significance of snow and wind observations in meteorological nowcasting and disaster *** disclose the phenomenon of the geohazard hysteresis to the precipitation peak resulting from the top-down(i.e.,precipitation-runoff and surface-deep soil moisture)peak *** work is expected to enhance the precision of susceptibility assessment models and the reliability of short-term forecasts for mountain geohazards.

关键词： Mountain geohazards Environmental factors Climate change geoDetector Southwest China

Miocene paleoenvironmental evolution based on benthic foraminiferal assemblages in the Lufeng Sag, northern South China Sea

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Acta Oceanologica Sinica 2019年第3期38卷 124-137页

作者： Liyuan xue Xuan Ding Renjie Pei Xiaoqiao Wan School of Ocean Sciences China University of Geosciences School of Earth Sciences and Resources China University of Geosciences

The Miocene epoch marks the most crucial period during the Cenozoic cooling trend, characterized by the Middle Miocene Climatic Optimum(MMCO) and a series of short–lived cooling events(Miocene isotope events).To understand the paleoenvironmental evolution along the shallow water shelf in the South China Sea during the Miocene, the benthic foraminiferal assemblage and total organic carbon content(TOC) were analyzed at Hole LF14 located in the Lufeng Sag, northern South China Sea. Three benthic foraminiferal assemblages(e.g., the Uvigerina spp. assemblage, the Cibicides spp. assemblage, and the Cibicidoides spp. assemblage), corresponding to different watermass conditions, were recognized based on q–mode factor analysis. Early studies suggested that Hole LF14 was deposited under semienclosed bay, middle to outer shelf or even upper bathyal environment during ～18.7–4.53 Ma. The dominant Uvigerina spp. assemblage was characterized by low diversity and shallow infaunal to infaunal species, indicating a warm, low–oxygenation and eutrophic conditions since the Early Miocene to MMCO(～18.7–14.24 Ma). An abrupt sea level drop and significant faunal changes were recorded during 14.24–13.41 Ma, suggesting development of the East Antarctic Ice Sheets, which resulted in a drop of sea level and change in benthic foraminiferal assemblages along the shallow water shelf. Beyond the Uvigerina ***, the Cibicides spp. assemblage became important during the middle–late Middle Miocene(14.24–11.54 Ma). This assemblage was dominated by epifaunal species with relative high diversity, suggesting high–energy, high–oxygenation and oligotrophic conditions with episodic supply of organic food. The dominant Cibicidoides spp. assemblage with high diversity, indicates a mesotrophic conditions with relative high–oxygen content during the Late Miocene to Pliocene(11.54–4.53 Ma). The appearance and continuous occurrence of Ammonia spp. and Pseudorotalia spp. since 10.02 Ma, may reflect the i

关键词： South China Sea Lufeng Sag Miocene benthic foraminiferal assemblage total organic carbon shelf paleoenvironment

Spatially-Resolved Crystallization of Amorphous Silicon Films on the glass Substrate by Multi-beam Laser Interference

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Journal of Materials Science & Technology 2007年第4期23卷 465-467页

作者： Zhongfan LIU xuede YUAN xue HAO F.Muecklich College of Physical Science and Technology Dalian University Dalian 116622 China Institute of Functional Materials University of Saarland Saarbruecken 66123 Germany

Laser interference induced crystallization of amorphous silicon （a-Si） on the glass substrate was performed using a q-switched Nd：YAg （yttrium aluminum garnet） laser. White light interferometer （WLI） and atomic force microscope （AFM） were used to characterize the morphology of the structured films, while X-ray diffraction （XRD）, combined with the AFM, was used to analyse the crystalline structure of the film. The experimental results show that the laser energy density above a certain threshold, in the range of 400-500 mJ/cm2,triggers the patterned crystallizations which take the form similar to the laser intensity distribution. For the patterned crystallization under multipulse exposure, a definite polycrystalline structure with individual phases was observed by XRD. The difference in feature form, e.g., deepened craters or heightened lines, is related to the laser energy density relative to the threshold of evaporation of the material.

关键词： Pulsed laser Laser interference Amorphous silicon Crystallization

Mechanisms leading to the frequent occurrences of hypoxia and a preliminary analysis of the associated acidification off the Changiiang estuary in summer

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Science China Earth Sciences 2017年第2期60卷 360-381页

作者： WEI qinSheng WANg BaoDong YU Zhigang CHEN JianFang xue Liang Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationOcean University of ChinaQingdao 266100China First Institute of Oceanography State Oceanic AdministrationQingdao 266061China Laboratory of Marine Ecology and Environmental Science Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China Second Institute of Oceanography State Oceanic AdministrationHangzhou 310012China

Based on literature data and shipboard observations,this study investigated the main environmental characteristics of the seafloor topography,current field,front,and upwelling that are closely related to hypoxia occurrence off the Changjiang *** physical processes of the plume front and upwelling off the Changjiang estuary in summer were *** vertical distribution pattern of the plume front was closely related to the *** reviewing and analyzing the historical summer hypoxia events off the Changjiang estuary,we statistically demonstrated the spatial structure of the horizontal distribution of the hypoxic zone and investigated the location of occurrence zone of the *** found that the dissolved oxygen(DO)concentration on the inner continental shelf off the estuary showed a"V"shape in relation to station ***,we noted that the hypoxic water on the inner continental shelf mostly occurred on the slopes with steep seafloor *** on the current understanding of the hypoxic mechanisms off the Changjiang estuary,we analyzed the biogeochemical mechanisms that could cause the steep terrain off the Changjiang estuary to become the main areas prone to summer hypoxia and explained the internal relations between the location of the hypoxic zone on the slopes and the plume front and *** plume front and upwelling off the Changjiang estuary and their coupling were important driving forces of summer *** continuous supply of nutrients affected by the interaction of the plume front extension of the Changjiang Diluted Water(CDW)and upwelling and the favorable light conditions were important mechanisms causing the phytoplankton blooms and benthic hypoxia off the Changjiang estuary in *** analyzing oxygen utilization,organic carbon mineralization,and nutrient regeneration in the hypoxic zone,we observed that the significant oxygen utilization process off the Changjiang estuary in summer also mainly occurred near the

关键词： Changjiang estuary Hypoxic zone Upwelling Front Nutrient regeneration Biogeochemistry Acidification

A gENERAL AVERAgINg METHOD FOR AFFINE PERIODIC SOLUTIONS

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Acta Mathematica Scientia 2024年第6期44卷 2207-2224页

作者： xue YANg Jiamin XINg Yong LI College of Mathematics Jilin UniversityChangchun 130012China School of Mathematics and Statistics and Center for Mathematics and Interdisciplinary Sci Northeast Normal UniversityChangchun 130024China

We consider the persistence of affine periodic solutions for perturbed affine periodic ***(q,T)-affine periodic solutions have the form x(t+T)=qx(t)for all t∈R,where T>0 is fixed and q is a nonsingular *** are a kind of spatiotemporal symmetric solutions,*** *** give the averaging method for the existence of affine periodic solutions in two situations:one in which the initial values of the affine periodic solutions of the unperturbed system form a manifold,and another that does not rely on the structure of the initial values of the unperturbed system's affine periodic *** transversal condition is determined using the Brouwer *** also present a higher order averaging method for general degenerate systems by means of the Brouwer degree and a Lyapunov-Schmidt reduction.

关键词： affine-periodic solution perturbed system Brouwer degree averaging method

Phase composition, morphology and element contents of micro-arc oxidation ceramic coatings on Ti–6Al–4V alloy under different calcination conditions

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Rare Metals 2016年第11期35卷 836-840页

作者： guo-Dong Hao xue-long Hao Zu-Fang Zhu Department of Chemistry Mudanjiang Normal University National Center of Analysis and Testing for Nonferrous Metals and Electronic Materials General Research Institute for Nonferrous Metals

Compound ceramic coatings with the main crystalline of Al_2TiO_5（in the as-prepared coating without treatment） were prepared in situ on the surface Ti-6Al-4V alloy by means of pulsed bipolar micro-arc oxidation in Na AlO_2 solution. For the purpose of studying the antioxidation properties of the samples, the coated samples treated in argon and the as-coated samples were calcined in air at 1000 °C. And the related characteristics were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and X-ray fluorescence（XRF） spectroscopy, respectively. The results show that, when it was calcined in air for 1 h, Al_2TiO_5in the as-prepared coating decomposed and transformed into α-Al_2O_3 and rutile TiO_***, after almost 4 h in argon, Al_2TiO_5in the asprepared coating decomposed and the final coating surface contents are completely α-Al_2O_3, and those of the middle interface are mainly Al_2O_3 and Ti_2O_3. The morphologies of the coatings after calcination in argon and air are ***-temperature oxidation occurred violently in the alloy substrate without coatings. Furthermore, the weight gain curves of the as-prepared samples and the coated samples treated in argon both show a parabolic shape.

关键词： Micro-arc oxidation Ti-6AI-4V Argon High-temperature oxidation

Anisotropy of the Wear Behavior for Carbon Nanotube-Reinforced 6061Al Composites

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Acta Metallurgica Sinica(English Letters) 2023年第5期36卷 814-826页

作者： X.N.Li J.F.Zhang W.H.xue K.Ma P.Y.Li Z.Y.Liu B.L.Xiao D.R.Ni q.Z.Wang D.Wang Z.Y.Ma School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

Carbon nanotube(CNT)-reinforced 6061Al(CNT/6061Al)composites with directionally aligned CNT were fabricated,and their wear behavior was *** results indicate that the wear properties of CNT/6061Al composites exhibited a significant anisotropy.A certain CNT concentrations(1 wt%and 2 wt%)could effectively improve the wear resistance of CNT/6061Al composites along the CNT circumferential and CNT radial directions for the load transfer,grain refinement and self-lubrication effect of *** Brass{011}and{112}textures inhibited the load transfer effect of CNT along the CNT radial direction,resulting in a better wear resistance along CNT circumferential direction than CNT radial *** the CNT axial direction,the weak deformability of composites caused by the intensifyingfiber texture was the main reasons for the poor wear resistance of CNT/6061Al composites with increasing CNT concentration.

关键词： Carbon nanotube Metal matrix composite Wear Anisotropy

Construction and evaluation of anti-gastrin immunogen based on P64K protein

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World Journal of gastroenterology 2006年第13期12卷 2040-2046页

作者： Xiang-Hua Xiong Hong-Liang Zhao Chong xue Wei Zhang Bing-Fen Yang xue-qin Yao Zhi-Min Liu Department of Microbiologic Engineering Beijing Institute of Biotechnology Beijing 100071 China

AIM： To construct two kinds of anti-gastrin immunogen based on P64K protein from Neisseria rneningitids and to compare their immunogenic effect. METHODS： g17P64K gene was cloned and ligated into pET28a plasmid, then transformed into BL21（DE3）. After inoculation of LB medium and IPTg induction, the recombinant protein was solubly expressed at a high level. The purification of g17P64K fusion protein was similar to that of P64K. An initial step of purification consisting of 30% saturated ammonium sulfate precipitation was done, Additional fine optimizations included phenyl-sepharose, g200 Sephadex gel filtration and q-sepharose anion exchanger chromatography. Highly purified protein was obtained and sequenced at the N-terminal amino acid residues. Polypeptide was synthesized by Fmoc solid phase chemical method and cross-linked to carrier protein P64K and DT mutant by MBS method and then the rabbit anti-gastrin 17 antibody was prepared by immunizing rabbit with cross-linked and fused protein. The titer and the activity in vitro of antibody were assessed. RESULTS： g17P64K gene and the recombinant bacteria were obtained. After four steps purification, protein sample that has the purity above 90% was achieved. At the 84^th day after the first immunization, the titer of antibody against cross-linked protein reached 51 200. Evaluation of the antibody in vitro manifested that it had a high inhibitory activity on the growth of tumor cell SW480. CONCLUSION： The P64K-polypeptide cross-linked immunogen immunized rabbit and achieved a higher titer antibody against gastrin 17 than the g17P64K fusion protein immunogen, which could inhibit the growth of the tumor cell SW480.

关键词： gastrin P64K protein therapeutic vaccine