Seasonal and interannual variability of primary and export production in the South China Sea: a three-dimensional physical-biogeochemical model study

To investigate the seasonal and interannual variations in biological productivity in the South China Sea (SCS), a Pacific basin-wide physical - biogeochemical model has been developed and used to estimate the biological productivity and export flux in the SCS. The Pacific circulation model, based on the Regional Ocean Model Systems (ROMS), is forced with daily air-sea fluxes derived from the NCEP (National Centers for Environmental Prediction) reanalysis between 1990 and 2004. The biogeochemical processes are simulated with a carbon, Si(OH)(4), and nitrogen ecosystem (CoSiNE) model consisting of silicate, nitrate, ammonium, two phytoplankton groups (small phytoplankton and large phytoplankton), two zooplankton grazers (small micrograzers and large mesozooplankton), and two detritus pools. The ROMS-CoSiNE model favourably reproduces many of the observed features, such as ChI a, nutrients, and primary production (PP) in the SCS. The modelled depth-integrated PP over the euphotic zone (0-125 m) varies seasonally, with the highest value of 386 mg C m (-2) d (-1) during winter and the lowest value of 156 mg C m (-2) d (-1) during early summer. The annual mean value is 196 mg C m (-2) d (-1). The model-integrated annual mean new production (uptake of nitrate), in carbon units, is 64.4 mg C m (-2) d (-1) which yields an f-ratio of 0.33 for the entire SCS. The modelled export ratio (e-ratio: the ratio of export to PP) is 0.24 for the basin-wide SCS. The year-to-year variation of biological productivity in the SCS is weaker than the seasonal variation. The large phytoplankton group tends to dominate over the smaller phytoplankton group, and likely plays an important role in determining the interannual variability of primary and new production.

企业经营风险决策的组织行为学研究

This thesis has investigated the risk preferences of the Chinese company managers in kinds of simulated decision situations and their perceptions of risk concerning types of business decisions. Four studies are conducted: Study I is utility analysis. 214 company managers and 46 middle - school headmasters have responded to Utility Measurement Survey. The results indicate: (1) The risk preferences of the managers vary in the different decision situations. In most of the situations, most of the managers are risk aversion; In few situations, they are risk-seeking. (2) In some of the decision situations, there are significant differences on risk preference between business managers and school headmasters, male managers and female managers, senior managers and junior managers, managers with high qualifications and managers with low qualifications, non-state-owned firms' managers and state-owned firms' managers, medium-small sized firms' managers and large-sized firms' managers. In the other situations there aren't significant differences between them. (3) In all of the decision situations, so significant differences on risk preference are found among managers with different marriage, experience, age and education. Study II is risky decision simulation. The Risky Decision Situations Simulation Survey is administered to 82 company managers. The result indicates that firm culture, business condition, survival limit and risk preference of the superior influence the managers' risk decision-making behavior. Study III is perceptions of business decision risks. 68 company managers have filled in Decision Cases Risk Perception Inventory. The results indicate: (1) Inaccurate market analysis and prediction, instable politics and the changes of economic policy are the more risky elements to strategy decision. (2) Erroneous market analysis and prediction, appearance of new technology and the changes of market demands are the more risky elements to investment decision. (3) Poor quality control, backward technology and too large stocks are the more risky elements to production decision. (4) Shortage of development fund, wrong choice in development project and limitation of the development ability are the more risky elements to new production development decision. (5) No payment of the foreign partner's capital, the changes of national relevant policy, difficulty in marketing, too high selling prices of foreign partner's equipments are the more risky elements to joint-venture decision. (6) Unfamilarity with oneself and misjudgement in qualification of oneself are the more risky elements to personnel decision. (7) Bad market of the product, defects in product quality and the changes of consumers demands are the more risky elements to marketing decision. (8) Wrong strategy and ambiguous goals are the more risky elements to public relation decision. (9) Violation of the law, ambiguous goals and poor creation are the more risky elements to advertisement decision. (10) Deterioration of diplomatic relations, unsuitable products for foreign consumers and unfamilarity with foreign market are the more risky elements to international business decision. Study IV is structured interview. 5 company managers have answered all questions of the Interview Questionnaire. The results indicate: (1) The managers think that risks are the possible unfavourable consequences of decisions; (2) The self-ratings of the managers coordinate with the results of utility measurement; (3) The managers admit that risks always accompany bussiness decision; (4) Individual difference is found among managers on risk perception. This thesis has also pointed out the important implications of the research and discussed several further questions.

Production of new superheavy Z=108-114 nuclei with U-238, Pu-244, and Cm-248,Cm-250 targets

Within the framework of the dinuclear system (DNS) model, production cross sections of new superheavy nuclei with charged numbers Z=108-114 are analyzed systematically. Possible combinations based on the actinide nuclides U-238, Pu-244, and Cm-248,Cm-250 with the optimal excitation energies and evaporation channels are pointed out to synthesize new isotopes that lie between the nuclides produced in the cold fusion reactions and the Ca-48-induced fusion reactions experimentally, which are feasible to be constructed experimentally. It is found that the production cross sections of superheavy nuclei decrease drastically with the charged numbers of compound nuclei. Larger mass asymmetries of the entrance channels enhance the cross sections in 2n-5n channels.

Fermentative hydrogen production by the new marine Pantoea agglomerans isolated from the mangrove sludge

A new fermentative hydrogen-producing bacterium was isolated from mangrove sludge and identified as Pantoea agglomerans using light microscopic examination, Biolog test and 16S rRNA gene sequence analysis. The isolated bacterium, designated as P. agglomerans BH-18, is a new strain that has never been optimized as a potential hydrogen-producing bacterium. In this study, the culture conditions and the hydrogen-producing ability of P. agglomerans BH-18 were examined. The strain was a salt-tolerant facultative anaerobe with the initial optimum pH value at 8.0-9.0 and temperature at 30 degrees C on cell growth. During fermentation, hydrogen started to evolve when cell growth entered late-exponential phase and was mainly produced in the stationary phase. The strain was able to produce hydrogen over a wide range of initial pH from 5 to 10, with an optimum initial pH of 6. The level of hydrogen production was affected by the initial glucose concentration, and the optimum value was found to be 10 g glucose/l. The maximum hydrogen-producing yield (2246 ml/l) and overall hydrogen production rate (160 ml/l/h) were obtained at an initial glucose concentration of 10 g/l and an initial pH value of 7.2 in marine culture conditions. In particular, the level of hydrogen production was also affected by the salt concentration. Hydrogen production reached a higher level in fresh culture conditions than in marine ones. In marine conditions, hydrogen productivity was 108 ml/l/h at an initial glucose concentration of 20 g/l and pH value of 7.2, whereas, it increased by 27% in fresh conditions. In addition, this strain could produce hydrogen using glucose and many other carbon sources such as fructose, sucrose, sorbitol and so on. As a result, it is possible that P. agglomerans BH-18 is used for biohydrogen production and biological treatment of mariculture wastewater and marine organic waste. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

New route for light olefins production from chloromethane over HSAPO-34 molecular sieve

HSAPO-34 molecular sieve was employed in chloromethane conversion and showed high performance in activity and selectivity in production of light olefins. Our detailed IR investigation allowed the identification of the active sites and the adsorbed species and demonstrated that the conversion started from 350 degrees C with alkoxy group as the intermediate. The fixed-bed catalytic testing evidenced that in the range of 350-500 degrees C, 70-80% of chloromethane was transferred to ethylene, propylene and butenes. Increasing reaction temperature favors the conversion and enhances the yield of lighter olefins. A very important reversible phenomenon, the breaking of Al-O-P bonds upon adsorption of HCl, a main product of reaction to generate a large amount of P-OH groups and the recovery of Al-O-P upon removal of HCI was revealed. (c) 2005 Elsevier B.V. All rights reserved.

Saprolegnia brachydanis, A New Oomycete Isolated from Zebra Fish

Saprolegnia brachydanis is described from zebra fish (Brachydanio rerio) in Wuhan, Hubei Province, China. The species is illustrated and compared with other species of the genus. The distinctive characteristics of S. brachydanis are the production of glomerulate oogonia wrapped around by predominantly monoclinous antheridia which can be up to eight in one oogonium. The oogonial stalks are short, straight, or curved and the antheridia, twisted, can enwind one or more oogonia. The oospores cannot mature or easily abort. Morphological features of the oomycete and the ITS sequence of its rDNA as well as the comparison with related species are discussed in this article.

Optimization of biodiesel production from trap grease via acid catalysis

As a kind of waste collected from restaurants, trap grease is a chemically challenging feedstock for biodiesel production for its high free fatty acid (FFA) content. A central composite design was used to evaluate the effect of methanol quantity, acid concentration and reaction time on the synthesis of biodiesel from the trap grease with 50% free fatty acid, while the reaction temperature was selected at 95 degrees C. Using response surface methodology, a quadratic polynomial equation was obtained for ester content by multiple regression analysis. Verification experiments confirmed the validity of the predicted model. To achieve the highest ester content of crude biodiesel (89.67%), the critical values of the three variables were 35.00 (methanol-to-oil molar ratio), 11.27 wt% (catalyst concentration based on trap grease) and 4.59 h (reaction time). The crude biodiesel could be purified by a second distillation to meet the requirement of biodiesel specification of Korea.