关于Gurney公式的强度效应修正

为了使Gurney公式能够在考虑材料强度的前提下预测爆轰驱动速度,采用量纲分析的方法,分析了影响柱壳爆轰驱动的主要因素,建立了抛射速度与主要物理量的函教关系.此函数关系经分离变量后,分别通过理论分析和数值仿真予以确定.分析表明,随着屈服应力的提高,壳体的径向极限速度下降,断裂时间提前.柱壳爆轰驱动的强度效应不容忽略.利用炸药爆速、炸药与柱壳的质量比、柱壳材料的屈服强度和密度等参数,通过拟合公式能够预测柱壳爆轰驱动的极限膨胀速度.

Study of Apiosoma piscicola (Blanchard 1885) occurring on fry of freshwater fishes in Hongze, China with consideration of the genus Apiosoma

Apiosoma piscicola (Blanchard 1885) was reported from fry of Carassius auratus (Var. pengze) and Ctenopharyngodon idella during parasite surveys in May 2005 and June 2006 at Hongze Lake Fish Hatchery, Jiangsu province, China. Twelve morphometric parameters were used to describe this peritrich in detail in the present study and comparisons were made with other reports. Its synonyms, Glossatella cylindriformis (Chen 1955) and Apiosoma magna (Banina 1968), were clarified based on reliable data. A. piscicola was still considered somewhat host-specific by us, especially to cyprinids, although it shows a quite wide limit of host variability. The telotroch was also observed, and its structures were described herein. Besides, the difficulties of the generic taxonomy were discussed and some suggestions were given.

Immunization of rainbow trout fry with Ichthyophthirius multifiliis sonicate: protection of host and immunological changes

Rainbow trout fry (10 weeks post hatch) were immunized (injection or immersion) with sonicated formalin-killed trophonts of the fish parasitic ciliate Ichthyophthirius multifiliis. Challenge infections 22 days after immunization showed a relative protection represented by significantly fewer established parasites and lower prevalence in the immunized groups compared to the controls. Associations between the obtained protection and changes in differential leukocyte counts, haematocrit values, anti Ichthyophthirius multifiliis antibodies, mucous cell density and some epidermal cell markers were investigated. No changes in antibody titers, haematocrit values and mucous cell counts were associated with the response; however, a minor change in peripheral blood neutrophils and epidermal cell markers were found.