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Bacterial community in sediment from the Western Pacific "Warm Pool" and its relationship to environment

Science China Earth Sciences 2005年第2期48卷 282-290页

作者： ZENG Runying ZHAO Jing ZHANG Rui LIN Nianwei Key Laboratory of Marine Biotechnology Third Institute of OceanographyState Oceanic AdministrationXiamen361005China Key Laboratory of Marine BiotechnologyThird Institute of OceanographyState Oceanic AdministrationXiamen361005China Key Laboratory of Marine BiotechnologyThird Institute of OceanographyState Oceanic AdministrationXiamen361005China Key Laboratory of Marine BiotechnologyThird Institute of OceanographyState Oceanic AdministrationXiamen361005China

Total DNAs were extracted from different sections of deep sea sediment core sample collected from the Western Pacific "Warm Pool". The bacterial 16S ribosomal DNA (rDNA) clone libraries were constructed and analyzed by PCR-restriction fragment length polymorphism (RFLP) and DNA sequencing. The bacterial communities in these samples and their relationship to environment were analyzed consequently. The results indicated that among eight main bacterial groups found in these sediments, members of the γ-Proteobacteria were most abundant in each section of sediment core sample and the genus Colwellia belonging to γ-Proteobacteria was dominant in this area. Members of the α-Proteobacteria were found commonly existing in these samples, while members belonging to β-Proteobacteria were seldom detected. The diversity of bacterial communities from different sections of sediment core sample was δ- and ε-Proteo- bacteria and the bacterial group including genera Cytopahga, Flexibacteria and Bacteroides (CFB group). These bacteria all were inversely proportional to the depth of sediment. Phylogenetic analysis showed that there were 18%-30% and 15%-25% of total bacterial communities related to methane and sulfur metabolism respectively in each section of core sample, implicating that the metabolism of sulfur and methane played an important role in the substance and energy cycles of the Western Pacific "Warm Pool".

关键词： Western Pacific "Warm Pool", sediment, microbial diversity, carbon cycle, sulfur cycle.

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Mechanisms of suppressing cup-burner flame with water vapor

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Science China(Technological Sciences) 2008年第8期51卷 1222-1231页

作者： CONG BeiHua LIAO GuangXuan State Key Laboratory of Fire Science University of Science and Technology of ChinaHefeiAnhui 230026China Research Center for Combustion and Environmental Technology Shanghai Jiaotong UniversityShanghai 200030China

The mechanisms of suppressing a laminar methane-air co-flow diffusion flame formed on a cup burner with water vapor have been studied experimentally and numerically. The methane burned in a steel cup surrounded by a glass chimney. A mist generator produced fine droplets delivered though the glass chimney with air. These droplets were heated into water vapor when they went though the diffuser. The extinguishing limit was obtained by gradually increasing the amount of water vapor to replace the air in the coflowing oxidizer stream. Results showed that the agent concentration required for extinguishment was constant over a wide range of the oxidizer velocity, i.e., a so-called "plateau region". The measured extinguishing mass fractions of the agents were: (16.7 ± 0.6)% for H2O, (15.9 ± 0.6)% for CO2, and (31.9 ± 0.6)% for N2. The computation used the Fire Dynamics Simulator (FDS) de- veloped by the NIST. The numerical simulations showed that the predicted water vapor extinguishing limits and the flickering frequency were in good agreements with the experimental observations and, more importantly, revealed that the sup- pression of cup-burner flames occurred via a partial extinction mechanism (in which the flame base drifts downstream and then blows off) rather than the global extinction mechanism of typical counter-flow diffusion flames. And the flame-base oscillation just before the blow-off was the key step for the non-premixed flame extinction in the cup burner.

关键词： cup-burner flames water vapor extinguishing limit partial extinction

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Comparisons of Infrared Colors and Emission-line Intensities between Two types of Seyfert 2 Galaxies

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Chinese Journal of Astronomy and Astrophysics 2002年第5期2卷 408-418页

作者： Lin-Peng Cheng, Yong-Heng Zhao and Jian-Yan WeiNational Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 National Astronomical Observatories CAS NAOC Beijing China

We study the relation between the infrared colors, [OIII] emission lines, gaseous absorbing column density (NH),and the detectability of the polarized (hidden) broad-line region (HBLR) in a large sample of 75 Seyfert 2 galaxies (Sy2s). From the indicators of star-formation activity, f60/f100 and LFIR/LB, we find some evidence that the Sy2s without HBLR show higher star-formation activities than those with HBLR, in agreement with previous prediction. Also, we confirm that the HBLR Sy2s tend to have a larger luminosity ratio of the core to the host galaxy, suggesting that the HBLR Sy2s display more powerful AGN activity. However, the level of obscuration found in previous papers is nearly indistinguishable between the two types of Sy2s. The results support the statement that the non-HBLR Sy2s, with a weaker core component and a stronger star-formation activity component, are intrinsically different from the HBLR Sy2s, which are Sy1 systems with a hidden powerful AGN core and a low star-formation activity. The indications are that the non-HBLR Sy2s might be at an earlier evolutionary phase than the HBLR Sy2s.

关键词： galaxies: active - galaxies: Seyfert - polarization - star formation

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Experimental study on inhibition of low pressure premixed flat methane-oxygen flames by trifluoromethane

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Chinese Science Bulletin 2005年第14期50卷 1429-1434页

作者： CONG Beihua QI Fei LIAO Guangxuan KUANG Kaiqiang ZHOU Xiaomeng State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China National Synchrotron Radiation Laboratory University of Science andTechnology of China Hefei 230026 China

This paper presents measurements of combus- tion species of low pressure laminar premixed flat meth- ane-oxygen flames inhibited by trifluoromethane (CF3H) using synchrotron radiation-molecular beam mass spec- trometry (SR-MBMS). Fire suppression chemistry of CF3H is investigated by selective detection of combustion radicals and intermediates. Results show that SR-MBMS offers a powerful tool for studying fire suppression chemistry of ha- lon replacements, which may extensively detect combustion species in the inhibited flames, especially radicals and inter- mediates. The suppressant CF3H is completely consumed in the preheat zone of premixed flames and produces fluori- nated radicals such as CF3 and CF2. CF3 is the main radical participating in flame inhibition cycles in the reactive zone. Unlike HBr, HF produced by CF3H is very stable and will not act as a radical scavenger because the bond energy of H-F is much higher than that of H-Br, which is responsible for less effectiveness than conventional bromine-based sup- pressants.

关键词：火焰抑制三氟氯乙烯分子光谱测定术燃烧媒介

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Characterization of Soil Quality Under Vegetable Production Along an Urban-Rural Gradient

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Pedosphere 2003年第2期13卷 173-180页

作者： ZHANG MINGKUI, WANG MEIQING, LIU XINGMEI, JIANG HONG and XU JIANMINGCollege of Resource and Environmental Sciences, Zhejiang University, Hangzhou 310029 (China) College of Resource and Environmental Sciences Zhejiang University Hangzhou 310029

Human activity and urbanization result in urban-rural environmental gradients. Understanding effect of the gradients on soil properties is necessary for management of the soils around urban areas. In this study, soil quality of some vegetable fields was characterized along an urban-rural gradient in Shaoxing County, Zhejiang Province. Fifteen soil physical and chemical properties were evaluated by using principal component *** showed that there was a great variation in the soil quality along the gradient. From rural to urban zones, soil organic matter, water-stable aggregates, cation exchangeable capacity (CEC), total N and P, and available K increased, whereas soil pH value decreased. In addition, Pb, Cu, Ni, Co, Zn and Cr in the soils tended to be accumulated toward the urban zone. Sequential chemical extraction showed that mobility of all the heavy metals in the soils tended to increase from the rural to the urban zones. The variation of soil properties accounted for by the first principal component was significantly explained by the difference in application rates of municipal wastes.

关键词： principal component analysis soil quality urban-rural environmental gradient

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Geologic and geochemical features of the volatile-rich ore fluid and its tracing and dating in the Xuebaoding Beryl-Scheelite Vein Deposit,China

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Science China Earth Sciences 2002年第8期45卷 719-729页

作者：曹志敏任建国郑建斌徐仕进李佑国王汝成 T.SHOJ H.KANEDA S.KABAYASHI College of Marine Geology Ocean University of Qingdao Qingdao China State Key Laboratory of Mineral Deposits Research in Nanjing University Nanjing China Chengdu University of Technology Chengdu China University of Tokyo Tokyo Japan

Laser Raman spectrochemical analysis on single inclusion reveals that multi-phase fluid inclusions exist in the Xuebaoding Beryl- Scheelite Vein Deposit. Besides the solid daughter mineral, there are vapor CO2, liquid CO2, water-deficient CO2 and salt water solution from its center to the border. A close study on the fluid inclusion components and carbon, oxygen, helium and argon isotope tracing and dating suggests that the volatile-rich ore fluid might derive from postmagmatic fluid and rare element enrichment is the result of the mixture of the plutonic alkali granite with crustal material.

关键词： multi-phase fluid inclusion noble gases isotope Beryl- Scheelite Vein Deposit.

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Recent progress in polymer/layered double hydroxide nanocomposites

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Progress in Natural Science:Materials International 2006年第6期16卷 573-579页

作者： DING Peng, CHEN Wei and QU Baojun (State Key Laboratory of Fire Science and Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026, China) State Key Laboratory of Fire Science Department of Polymer Science and Engineering University of Science and Technology of China Hefei 230026 China

New developments in the studies of nanocomposites based on polymer matrixes and layered double hydroxides (LDHs) in recent years are reviewed combining our relative research work, among which the synthesis techniques, the physicochemical characterizations, and the improved material properties are especially discussed. The possible application of polymer/LDH nanocomposites is also proposed.

关键词： nanocomposite layered double hydroxide synthesis characterization structure property.

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Analysis of solid-liquid phase change heat transfer enhancement

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Science China(Technological Sciences) 2002年第6期45卷 569-575页

作者：张寅平王馨 Department of Building Science Tsinghua University Beijing China

Solid-liquid phase change processes have two important features: the process is an approximately isothermal process and the heat of fusion of phase change material tends to be much greater than its specific heat. Therefore, if any phase change material adjacent to a hot or cold surface undergoes phase change, the heat transfer rate on the surface will be noticeably enhanced. This paper presents a novel insight into the mechanisms of heat transfer enhancement induced by solid-liquid phase change based on the analogy analysis for heat conduction with an internal heat source and solid-liquid phase change heat transfer. Three degrees of surface heat transfer enhancement for different conditions are explored, and corresponding formulae are written to describe them. The factors influencing the degrees of heat transfer enhancement are clarified and their effects quantitatively analyzed. Both the novel insight and the analysis contribute to effective application of phase change heat transfer enhancement technique.

关键词： phase change, heat transfer enhancement, heat conduction.

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A class of fully third-order accurate projection methods for solving the incompressible Navier-Stokes equations

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Acta Mechanica Sinica 2005年第6期21卷 542-549页

作者： Yuxin Ren Yuxi Jiang Miao'er Liu Hanxin Zhang Department of Engineering Mechanics Tsinghua University Beijing 100084 China CNOOC Research Center Beijing China National Key Laboratory for CFD Beijing China

In this paper, a fully third-order accurate projection method for solving the incompressible Navier-Stokes equations is proposed. To construct the scheme, a continuous projection procedure is firstly presented. We then derive a sufficient condition for the continuous projection equations to be temporally third-order accurate approximations of the original Navier-Stokes equations by means of the localtruncation-error-analysis technique. The continuous projection equations are discretized temporally and spatially to third-order accuracy on the staggered grids, resulting in a fully third-order discrete projection scheme. The possibility to design higher-order projection methods is thus demonstrated in the present paper. A heuristic stability analysis is performed on this projection method showing the probability of its being stable. The stability of the present scheme is further verified through numerical tests. The third-order accuracy of the present projection method is validated by several numerical test cases.

关键词： Incompressible Navier-Stokes equations projection methods - Third-order scheme - Local truncation error

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Transition of Quaternary glacial cyclicity in deep-sea records at Nansha,the South China Sea

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Science China Earth Sciences 2001年第10期44卷 926-933页

作者：汪品先田军成鑫荣 Key Laboratory of Marine Geology Ministry of Education Tongji University Shanghai China

High-resolution oxygen isotope records over the last 2249 ka (MIS 1-86) have been obtained from cores of the upper section (105.08 m) at ODP Site 1143 (water depth of 2772 m)drilled in the Nansha area, southern South China Sea. The sampling resolution is at about 2 ka intervals, resulting in one of the best oxygen isotope records over the global ocean. The oxygen isotope curves, displaying details in the Pleistocene glacial cycles, have revealed a nearly 300 ka long stage of transition from a predominant 40 ka to 100 ka periodicity. Therefore, the 'Mid-Pleistocene Revolution' should be considered as a process of transition rather than an abrupt change. Within the 100 ka glacial cycles, the changes in tropical sea surface water were found to lead those in high-latitude ice sheet. Our comparisons show that the ice sheet expansion and the glacial stage extension in the Northern Hemisphere with the 100 ka cycles must have been driven not by ice sheet itself, but by processes outside the high latitudes of the Northern Hemisphere.

关键词： Quaternary glacial cycles Mid-Pleistocene Revolution oxygen isotope stages Nansha area

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