Summertime ciliate and copepod nauplii distributions and micro-zooplankton herbivorous activity in the Laizhou Bay, Bohai Sea, China

The abundance and biomass of ciliated protozoa and copepod nauplii were investigated at 21 grid stations and two anchored stations in the Laizhou Bay, Bohai Sea, China in June 1998. Dilution incubations were carried out to investigate micro-zooplankton grazing pressure at the anchored stations during spring tide and neap tide. The dominant species were Tintinnopsis amoyensis, T. chinglanensis, T. pallida and aloricate ciliates. A total of 13 species of tintinnids were found. The total abundance of ciliates and nauplii ranged from 30 to 2390 ind l(-1) at grid stations. Tintinnopsis amoyensis was the only ciliate found at the anchored stations and in concentrations which varied from 0 to 6700 ind l(-1). The spatial distribution of ciliates was patchy. Tintinnopsis amoyensis and T. pallida were distributed in the Weihe River mouth and Xiaoqinghe River mouth respectively. The aloricate ciliates, T. chinglanensis and Codonellopsis ostenfeldi dominated offshore in sequence. The water mixing process may affect the spatial pattern of the dominant ciliate species. The abundance and biomass of copepod nauplii were in the range of 0-140 ind l(-1) and 0-7 mu g C l(-1) respectively, with the peak appearing at grid station 15. The total biomass of ciliates and copepod nauplii was in the range of 1(.)5-25 mu g C l(-1). Water column biomass of ciliates and nauplii varied from 2(.)37 to 52(.)3 mg C m(-2). At the anchored stations, the phytoplankton growth rates ranged from undetectable to 0 21 d(-1) and micro-zooplankton grazing rates from 0 13 to 0(.)57 d(-1). The grazing pressure of micro-zooplankton were 12 to 43% of the chlorophyll standing stock and 84 to 267% of the chlorophyll (C) 2000 Academic Press.

Characteristics of anodic coatings oxidized to different voltage on AZ91D Mg alloy by micro-arc oxidization technique

With increasing applied voltage, three types of anodic coatings, passive film, micro-spark ceramic coating and spark ceramic coating were made by micro-arc oxidization (MAO) technique on AZ91D magnesium alloy in alkali-silicate solution. The structure, composition characteristics and the electrochemical properties of coatings were also studied with SEM, XRD and EIS (electrochemical impedance spectroscopy) technique, respectively. It is found that the electrochemical properties are closely related to the structure and composition characteristics of the anodic coatings. At the same time, the characteristics of the three types of anodic coatings differ significantly, among them, the micro-spark ceramic coating, prepared in the voltage range of 170similar to220V exhibits compact, homogeneous structure and highest corrosion-resistance.

基于软粘土微观特性的非线性固结理论研究

The land subsidence of soft clay is including natural and man-made content, which leads to the research on the mechanism of land subsidence constituted by two different aspects, which are studied by geological engineers and geologist. The main major research is focused on the effects of engineering. The land subsidence engineering of soil mechanics is caused by the consolidation and compression of soft clay, the content of which is including the micro-structural characteristics, the stress - strain constitutive relation, porous law, and consolidation theory. In this paper, it is discussed the nonlinear consolidation and compression theory of soft clay. The main studies and conclusions of this thesis are as follows. （1）The micro-structure and its stability are closely related to the engineering characters of soft clay. The stiffness and force connection status of micro-structure plays a controlling influence to its stability. （2）Under saturated state, clay particles remain in a non-full contact or non-contact status, so it is needed to modify the Terzaghi effective stress principle. With the discharge of pore water, the effective stress is increasing, and part of weakly bound-water begins flow, while the porosity and permeability are became lower. （3）It exist non-linear flow in soft clay, which is caused by the shear flow situation of weakly bounded-water. In this case, permeability coefficient is a nonlinear function of hydraulic gradient. （4）In the initial consolidation stage of soft clay in the initial stage, the porous flow is mainly caused by the excretion of free water. With the decrease of free water content, combined bonded-water start to supply free water. At the later stage of consolidation, the flow of fluid is mainly consisted by weakly bounded-water. The exchange between bonded-water and free water is played a role, which slows down the consolidation process.

非均匀性对岩石破裂过程影响的研究

Rock heterogeneity plays an important role in rock fracturing processes. However, because fracturing is a dynamic process and it is very difficult to quantify materials' heterogeneity, most of the theories dealing with local failure were based on the homogeneity assumption, very few involving stress distribution heterogeneity and successive local failure due to rock heterogeneity. Therefore, based on various references, the author studied the laws and mechanism of influences of heterogeneity on rock fracturing processes, under the frame of the project "Study on Associate Mechanism between Rock Mass Fracture and Strength Failure", funded by Nation Natural Science Fund. the research consists of such aspects as size effect correction to rock fracture parameters, SEM (Scanning Electron Microscope) real-time observation on rock samples under different loads, micro-hardness testing, and numerical simulating based on microstructure. There are some important research results as followed: 1. Unifying formula for nonlinear and non-singularity correction, simplifying the complex process of correcting size effect on rock fracture toughness. 2. Using the methods of micro-hardness testing mineral grain and random jointing micrograph digitizing mineral slice, preliminarily solving the problems of numerical simulating and quantitatively describing the heterogeneous strength and its distribution rules, which has certain innovation and better practicability. 3. Based on SEM real-time observation, studying the micro-process of fracturing in marble, sandstone, granite, and mushroom stone samples with premanufactured cracks under tension, pure-shear and compression-shear conditions. Strength Failure was observed: there was some kind failure occurred before Fracture Failure in marble and sandstone samples with double cracks under pure-shearing. It is believed that the reason of strength failure developing is that stress concentrations is some locations are larger than that near the end of pre-manufactured cracks. 4. Based on the idea that rock macro-constitute is composed of complex microstructure, the promising method used to handle heterogeneity considers not only the heterogeneity of the rock medium, but also the heterogeneity of the rock structure. 5. Putting forward two types of rock strength failure: medium strength failure induced by heterogeneity of rock medium and structure strength failure induced by heterogeneity rock structure. 6. By evaluating potential fracture cell with proper failure priority, the numerical simulating method solved the problem of simulating the coextensive strength failure and fracture failure with convention strength failure rules. The result of numerical analysis shows that the influence of heterogeneity on rock fracturing processes is evident. The sinuosity of the rock fracture-propagation path, and the irregular fluctuation of loading displacement curve, is mainly controlled by the heterogeneity of rock medium.

A study on the dependence of the micro-pore configurations on the volatilization and the burn processes of the organic compounds in the matrix of molten carbonate fuel cells

The micro-pore configurations on the matrix surface were studied by SEM. The matrix of molten carbonate fuel cell (MCFC) performance was also improved by the better coordination between the reasonable radius of the micro-pores and the higher porosity of the cell matrix. The many and complicated micro-pore configurations in the cell matrix promoted the volatilization of the organic additives and the burn of polyvinyl butyral (PVB). The smooth volatilization of the organic additives and the complete burn of PVB were the significant factors for the improved MCFC performance. Oxygen diffusion controlled-burn mechanism of PVB in the cell matrix was proposed. (C) 2002 Published by Elsevier Science Ltd.