Velocity and Sediment Concentration Profiles in Sediment-Laden Flows

A theoretical analysis of velocity profiles in sediment-laden flows is presented by means of Prandtl-Karman mixing length theorem. The study shows that the upward velocity of liquid-phase caused by settling sediment leads to the invalidity of the log-law and Rouse equation. The theoretical analysis takes into account the upward velocity and shows: 1) the mean velocity in sediment-laden flows follows the log-law, but the Karman constant reduces in the main flow region, 2) sediment concentration reduces the mixing length of fluid particles, 3) flow resistance reduces with the presence of sediment concentration, and 4) the sediment concentration profile deviates from the well know Rouse equation. The experimental data agree well with the equations derived on the basis of non-zero wall velocity. It is found that the wall-normal velocity should not be neglected for density gradient flows because it induces more than for pure water flows.     

北部湾的环流和水团对季节性强迫的响应

In the past 20 a, the gulf-scale circulation in the Beibu Gulf has been commonly accepted to be driven by a wind stress or density gradient. However, using three sensitive experiments based on a three-dimensional baroclinic model that was verified by observations, the formation mechanisms were revealed： the circula- tion in the northern Beibu Gulf was triggered by the monsoon wind throughout a year; whereas the southern gulf circulation was driven by the monsoon wind and South China Sea （SCS） circulation in winter and sum- mer, respectively. The force of heat flux and tidal harmonics had a strong effect on the circulation strength and range, as well as the local circulation structures, but these factors did not influence the major circulation structure in the Beibu Gulf. On the other hand, the Beibu Gulf Cold Water Mass （BGCWM） would disappear without the force of heat flux because the seasonal thermocline layer was generated by the input of heat so that the vertical mixing between the upper hot water and lower cold water was blocked. In addition, the wind-induced cyclonic gyre in the northern gulf was favorable to the existence of the BGCWM. However, the coverage area of the BGCWM was increased slightly without the force of the tidal harmonics. When the model was driven by the monthly averaged surface forcing, the circulation structure was changed to some extent, and the coverage area of the BGCWM almost extended outwards 100%, implying the circulation and water mass in the Beibu Gulf had strong responses to the temporal resolution of the surface forces.     

Potassium channel in peripheral blood lymphocytes of turbot (Scophthalmus maximus)

In order to provide pertinent evidence of ion channel with immune response in the fish,whole cell patch-clamp technique was employed for potassium ion channel study in turbot(Scophthalmus maximus) . Lymphocytes were isolated by Percoll density gradient centrifugation from peripheral blood samples,and electrophysiological characters of the channel were analyzed. In the recorded cells,activated voltage of the channels was-42.5 ± 3.7 mV and the average peak current was 313.12 ± 28.2 pA. The channel was identified as voltage dependent,the current was outward and it could be inhibited by 10 mmol/dm 3 TEA or 5 mmol/dm 3 4-AP,a specific potassium channel inhibitor,identifying the existence of potassium channel in peripheral lymphocytes of the turbot.     

栉孔扇贝体内类支原体样生物的分离纯化

栉孔扇贝(Chlamys farreri)是我国北方诸省传统的一种养殖贝类.自20世纪90年代以来,北方海域养殖的栉孔扇贝灾难性的死亡事件屡有发生,1997年最甚.该贝一般呈现两个死亡高峰期:其一为春季(3～5月)死亡,在有些海区死亡率达50%以上;其二为夏季高温期(6～9月)死亡,一般在持续27℃以上高温天气(如在8月)死亡尤为严重,此期内死亡率高达80%以上,甚至有的海区100%死亡[1]1).     

栉孔扇贝体内寄生的病毒的分离纯化及其形态学观察

栉孔扇贝(Chlamys farreri)是我国传统海水养殖贝种,养殖范围主要分布于黄海、渤海沿岸的山东、河北、辽宁等地,但是,近年来因病害发生,造成了巨大的经济损失.扇贝大规模死亡流行病学调查研究已进行多年,流行病学调查、病理学、病原感染实验及病原分离纯化等研究初步认为类立克次体是扇贝(包括栉孔扇贝和海湾扇贝Argopecten irradians)的病原生物[1～4].在用泛影葡胺密度梯度离心纯化栉孔扇贝类立克次体时发现一种具囊膜的病毒粒子,本文首次报道栉孔扇贝体内该球形病毒纯化的形态学特征.