The combined effects of temperature and food supply on Calanus sinicus in the southern Yellow Sea in summer

The effects of temperature and food availability on the life history strategy of the planktonic copepod Calanus sinicus in the southern Yellow Sea in summer were studied in this paper. The fifth copepodite stage (CV) dominates the population in the central part of the southern Yellow Sea, where the Yellow Sea Cold Water Mass (YSCWM) occurs below the thermocline. Incubation experiments were conducted on CV C. sinicus caught from the YSCWM to examine the effects of temperature and food availability. Temperature at the surface (27degreesC) is lethal to CVs regardless of food availability. At the temperature in the middle of the thermocline (18degreesC), survival time of the specimens depends on food availability, being similar to20 days in treatments without extra food supply. At the temperature in the YSCWM (9degreesC), most animals survive at the end of 27 day incubation even in treatments without food supply. Developmental rate of CVs at 9degreesC without extra food supply is extremely low. The increase of either temperature or food supply promotes the developmental rate of CVs. According to these results, the surface layers with high temperature and low food abundance are detrimental for the survival and reproduction of C. sinicus. Low temperature and low food availability in the YSCWM help CV to maintain a much lower developmental rate and higher survival rate. The ecological trait of C. sinicus in the southern Yellow Sea in summer cannot be sufficiently explained solely by the effects of temperature.

Independence of alpine meadow plants from soil organic matter for nitrogen supply: evidence from stable nitrogen isotopes

Stable nitrogen isotope signatures of major sources of mineral nitrogen ( mineralization of soil organic nitrogen, biological N-2 fixation by legumes, annual precipitation and plant litter decomposition) were measured to relatively define their individual contribution to grass assimilation at the Haibei Alpine Meadow Ecosystem, Qinghai, China. The results indicated that delta N-15 values (- 2.40 parts per thousand to 0.97 parts per thousand) of all grasses were much lower than those of soil organic matter (3.4 +/- 0.18 parts per thousand) and mineral nitrogen ( ammonium and nitrate together,7.8 +/- 0.57 parts per thousand). Based on the patterns of stable nitrogen isotopes, soil organic matter (3.4 +/- 0.18 parts per thousand), biological N-2 fixation (0 parts per thousand), and precipitation (- 6.34 +/- 0.24 parts per thousand) only contributed to a small fraction of nitrogen requirements of grasses, but plant litter decomposition (- 1.31 +/- 1.01 parts per thousand) accounted for 67%.

Theoretical and experimental research on time-optimal trajectory planning and control of industrial robots

提出了一种用于工业机器人时间最优轨迹规划及轨迹控制的新方法，它可以确保在关节位移、速度、加速度以及二阶加速度边界值的约束下，机器人手部沿笛卡尔空间中规定路径运动的时间阳短。在这种方法中，所规划的关节轨迹都采用二次多项式加余弦函数的形式，不仅可以保证各关节运动的位移、速度 、加速度连续而且还可以保证各关节运动的二阶加速度连续。采用这种方法，既可以提高机器人的工作效率又可以延长机器人的工作寿命以PUMA560机器人为对象进行了计算机仿真和机器人实验，结果表明这种方法是正确的有效的。它为工业机器人在非线性运动学约束条件下的时间最优轨迹规划及控制问题提供了一种较好的解决方案。

华南震旦纪-寒武纪两期成磷事件及其地球动力学意义

Phosphorus is an important biological and ecological element that to a certain degree constrains ecological environment and nutrient (including carbon) cycling. Marine sedimentary phosphorites are the principal phosphorus supply of the mankind. In the eastern to southern margins of the Yangtze Craton, South China, there are two phosphogenetic events at the Doushantuo stage of the Late Sinian and the Meishucun stage of the Early Cambrian respectively, corresponding two explosion events of life across the Precambrian\Cambrian boundary. Phosphorus ores from the Sinian and Cambrian phosphate in South China can be classified roughly into two categories, namely, grained and non-grained phosphorites. Grained phosphorites, hosted in dolostone type of phosphogenetic sequences and with larger industrial values, occur mainly in margins of the Upper Yangtze Platform, formed in shallow-water environments with high hydraulic energy and influenced by frequent sea-level change. Non-grained phosphorites, hosted principally in black-shale type of phosphogenetic sequences and with smaller industrial values, are distributed mainly in the Jiangnan region where deeper-water sub-basins with low hydraulic energy were prevailing at the time of phosphogenesis. Secular change ofδ~(13)C, δ~(18) O, ~(86)Sr/~(87)Sr values of carbonates from Sinian and Cambrian sequences were determined. A negative abnormal ofδ~(13)C, δ~(18)O values and positive abnormal of 86Sr/87Sr values from the fossiliferous section of the Lowest Cambrian Meishucun Formation implies life depopulation and following explosion of life across the PrecambriamCambrian boundary. Based on a lot of observations, this paper put forward a six-stage genetic model describing the whole formational process of industrial phosphorites: 1) Phosphorus was transported from continental weathering products and stored in the ocean; 2) dissolved phosphates in the seawater were enriched in specific deep seawater layer; 3) coastal upwelling currents took this phosphorus-rich seawater to a specific coastal area where phosphorus was captured by oceanic microbes; 4) clastic sediments in this upwelling area were enriched in phosphorus because of abundant phosphorus-rich organic matters and because of phosphorus absorption on grain surfaces; 5) during early diagenesis, the phosphorus enriched in the clastic sediments was released into interstitial water by decomposition and desorption, and then transported to the oxidation-reduction interface where authigenic phosphates were deposited and enriched; 6) such authigenic phosphate-rich layers were scoured, broken up, and winnowed in shallow-water environments resulting in phosphate enrichment. The Sinian-Cambrian phosphorites in South China are in many aspects comparable with coastal-upwelling phosphorites of younger geological ages, especially with phosphorites from modern coastal upwelling areas. That implies the similarities between the Sinian-Cambrian ocean and the modern ocean. Although Sinian-Cambrian oceanic life was much simpler than modern one, but similar oceanic planktons prevail, because oceanic planktons (particularly phytoplanktons) are crucial for phosphate enrichment related to coastal upwelling. It implies also a similar seawater-layering pattern between the Sinian-Cambrian ocean and the modern ocean. The two global phosphate-forming events and corresponding life-explosion events at the Sinian and Cambrian time probably resulted from dissolved-phosphate accumulation in seawater over a critical concentration during the Earth's evolution. Such an oceanic system with seawater phosphorus supersaturation is evidently unstable, and trends to return to normal state through phosphate deposition. Accordingly, this paper put forward a new conception of "normal state <=> phosphorus-supersaturation state" cycling of oceanic system. Such "normal state <=> phosphorus-supersaturation state" cycling was not only important for the three well-known global phosphate-forming events, also related to the critical moments of life evolution on the Earth. It might be of special significance. The favorable paleo-oceanic orientation in regard to coastal-upwelling phosphorite formation suggests a different orientation of the Yangtze Craton between the Sinian time and the present time (with a 135° clockwise difference), and a 25° anti-clockwise rotation of the Yangtze Craton from late Sinian to early Cambrian. During the Sinian-Cambrian time, the Yangtze Craton might be separated from the Cathaysia Block, but might be still associated with the North China Craton.

An industrial scale dehydration process for natural gas involving membranes

An industrial scale dehydration process based on hollow fiber membranes for lowering the dew point of natural gas is described in this paper. A pilot test with the feed flux scale of 12x10(4) Nm(3)/d was carried out. Dew points of -8 degreesC-13 degreesC at a gas transport pressure in the pipeline of 4.6M Pa and methane recovery of more than 98% were attained. The water vapor content of the product gas could be maintained around 0.01 vol% during a continuous run of about 700 hours. The effects of feed flux and operation pressure on methane recovery and water vapor content were also investigated. Additionally, some auxiliary technologies, such as a full-time engine using natural gas as fuel and the utilization of vent gas in the process, are also discussed. A small amount of the vent gas from the system was used as a fuel for an engine to drive vacuum pumps, and the heat expelled from the engine was used to warm up the natural gas feed. The whole system can be operated in a self-sustainable manner from an energy point of view, and has a relatively high efficiency in the utilization of natural gas.