Collisional instability of the drift wave in multi-component plasmas

The collisional instability of the drift wave in a multi-component plasma is investigated. It is shown that when the electron and ion density gradients are different, e.g., due to the presence of a static third component or due to neutral drag effects, the drift mode becomes unstable. The instability is caused by the simultaneous action of the electron collisions with all other plasma species and the spatial difference of the density of the plasma components. This instability may be expected as a natural consequence of the stratification of a multi-component plasma placed in an external gravity field where it can operate for any amount of charge on heavy particles. Therefore it could develop in weakly ionized cold interstellar regions for example, when the heavy particles, i.e. charged grains, are a few tens of Å in size, and carry typically ±1,±2 charge. In the solar atmosphere, it may appear in the weakly ionized photospheric layers due to the convective motion of the neutral component.     

黄、东海海洋黄色物质的卫星反演

在对物理特性分析的基础上, 建立了黄、东海海域卫星离水辐射率黄色物质反演模式, 并利用2003年4月15日SeaWIFS卫星获得的黄、东海海域离水辐射率(Lw)数据反演给出了黄海中部—东海南部(北起33°52′N, 南到22°00′N; 西起122°36′E, 东止125°28′E)海域的黄色物质分布图。结果分析表明, 研究区给出的黄、东海海域黄色物质吸收系数在0.003—0.13m-1范围内, 与大西洋北海测得的黄色物质吸收系数比较接近, 但明显低于波罗的海和地中海, 更低于世界各地沿海海湾。平均而言, 比在太平洋点测黄色物质吸收系数值高约80%, 达0.09m-1左右。在水平分布上, 黄海海域的黄色物质吸收系数明显高于东海海域, 沿岸水域明显高于远海水域。受长江水系和黄海环流以及沿岸排污等要素的影响, 在长江口以外和黄海中、南部水域及其沿岸附近有明显的高吸收系数值聚集区。同时发现, 在黄海西部沿岸, 由于有较高反射率的高泥沙含量的影响, 对该区黄色物质的反演产生了较大的影响, 特别在苏北沿岸和长江口水域尤其如此。而在韩国、日本西海岸、浙江及福建沿岸水域则比较正常的给出了黄色物质的分布。     

Optimization of fluorescence in situ hybridization （FISH） for the identification of two polar coccoid green algae species

Standard FISH protocols using fluorochrome-labeled oligonucteotide probes have been successfully applied for in situ detection.However,optimized protocols of FISH for specific eukaryotes in marine environments are often not developed.This study optimized the conditions of fluorescence in situ hybridization (FISH) by using two polar isolated microalgae.The modified conditions were as follows: (1) 10 mg·mL-1 lysozyme solution pretreatment at 37℃ for 30 min;(2) the hybridization buffer including 20% formamide;(3) the hybridization condition was 47℃ for 6 h. The cells enumerated by FISH were compared with those enumerated by flow eytometry (FCM) and DAPI to confirm the cell loss and hybridization efficiency.The optimized protocol was also successfully applied to Arctic Ocean samples,which were found to be dominated by Micromonas sp.The modified protocol showed a high relative efficiency and could be successfully applied for the detection of specific microbial eukaryotes in environmental samples.