变角度水面矢量推进器性能分析

现行大方形系数两栖平台在水中排水航行,受到"兴波阻力墙"的影响,速度难以提高。为了减阻提速,以蛇怪蜥蜴为仿生对象,提出了一种变角度的水面矢量推进器,通过角度和转速控制,实现了驱动力矢量输出的新模式;增加了托举力和转矩驱动,为平台水上低阻高速航行提供了新思路。进一步结合PISO算法和两相流瞬态分析,建立了推进器的流体动力学模型,分析了运动参数和结构参数对三维驱动输出的影响,并进行了试验验证。结果表明:叶片角度从0°到90°增大,实现了驱动力输出角从-6.85°到51.95°的矢量连续变化,且存在驱动均衡输出区间[40°,60°];托举力与轮辐长度呈线性关系,且推进力、转矩与轮辐长度呈二次函数关系;随转速增加,驱动输出增加,转速为5 r/s时因流场恢复能力不足导致频率为转速的2倍;托举力随轮毂宽度、直径的增加而减小。研究结果为深入开展推进器驱动调节和平台航行控制打下基础。     

高地隙自走式喷雾机动力传动系统的设计

我国大田农作物中后期病虫害防治迫切需要高行间通过性的高效植保动力机械,因而提出了一种自走式高地隙喷杆式喷雾机的动力底盘设计方案。该动力底盘采用四轮驱动和全液压四轮转向结构,具有离地间隙高、水旱兼用及机动性好等特点。为此,进行了总体方案的设计及基本参数的确定,介绍了传动系统的方案设计及工作原理,并对变速箱传动方案进行了设计。同时,重点对行走动力传动系统传动比、喷药液压动力传动系统参数与发动机工作特性之间匹配进行研究,在保证喷雾机作业时施药行走速度与施药机具效率最佳匹配的前提下,发动机在燃料经济性较高的区域内工作,实现高效、节能和环保的设计目标。     

Osmoregulation in the mudskipper,Boleophthalmus boddaerti II. transepithelial potential and hormonal control

Boleophthalmus boddaerti submerged in 10%, 50% and 80% seawater (sw) for 7 days, had whole body transepithelial potentials (TEP) of 3.3, 18.3 and 22.9 mV, respectively. Hypophysectomy significantly decreased the TEP ofB. boddaerti and reversed the polarity of the TEP of the fish exposed to 10% sw.Hypophysectomy also significantly decreased the branchial Na⁺-K⁺ activated adenosine triphosphatase (Na⁺,K⁺-ATPase) activity but increased the activity of branchial HCO₃ ^–-Cl^– stimulated adenosine triphosphatase (HCO₃ ^–,Cl^–-ATPase) inB. boddaerti exposed to 10% sw. However, survival in 10% sw was not significantly impaired by hypophysectomy and no significant change in plasma osmolality and plasma Na⁺ and Cl^– concentrations was observed.Various doses of ovine-prolactin or salmon-prolactin were unable to restore the TEP of hypophysectomizedB. boddaerti in 10% sw to that of the sham-operated fish. However, cortisol increased TEP to a positive value in hypophysectomizedB. boddaerti, though it was still lower than the sham-operated control. Cortisol treatment also affected the plasma osmolality, plasma Na⁺ and Cl^– contents and branchial Na⁺,K⁺-ATPase and HCO₃ ^–,Cl^–-ATPase activities. Overall, the hormonal control of osmoregulation inB. boddaerti appeared to differ from that of other teleosts.     

大弹涂鱼寄生蛭治疗实验研究

报道了几种化学药物以及淡水和高盐度海水治疗大弹涂鱼寄生蛭的实验结果。单独使用 1 0mg/dm3 的敌百虫或 1 0 0× 1 0 -6(V /V)～ 2 0 0× 1 0 -6(V /V)的福尔马林以及混合使用 1 5 0× 1 0 -6(V /V)福尔马林 +0 5mg/dm3 (或 1 0mg/dm3 )的敌百虫对杀灭大弹涂鱼寄生蛭有明显的疗效且较安全。采用淡水浸泡治疗大弹涂鱼寄生蛭是最有效和最安全的方法。高盐度海水浸泡能使鱼蛭脱落 ,但也会导致大弹涂鱼死亡。硫酸铜和“鱼虫绝杀”不宜作为治疗大弹涂鱼寄生蛭的化学药物     

Adaptations of amphibious fish for surviving life out of water

There are a small number of fish species, both marine and freshwater, that exhibit a truly amphibious habit that includes periods of aerial exposure. The duration of emersion is reflected in the level of physical and physiological adaptation to an amphibious lifestyle. Fish that are only briefly out of water retain predominantly aquatic attributes whereas there are semi‐terrestrial species that are highly adapted to prolonged periods in the aerial habitat. Desiccation is the main stressor for amphibious fish and it cannot be prevented by physiological means. Instead, amphibious fish resist excessive water loss by means of cutaneous modification and behavioural response. The more terrestrially adapted fish species can tolerate considerable water loss and may employ evaporation to aid thermoregulation. The amphibious habit is limited to fish species that can respire aerially. Aerial respiration is usually achieved through modification to existing aquatic pathways. Freshwater air‐breathers may respire via the skin or gills but some also have specialized branchial diverticula. Marine species utilize a range of adaptations that may include modified gills, specialized buccopharyngeal epithelia, the intestine and the skin. Areas of enhanced respiratory activity are typified by increased vascularization that permits enhanced perfusion during aerial exposure. As with other adaptations the mode of nitrogenous elimination is related to the typical durations of emersion experienced by the fish. Intertidal species exposed on a regular cycle, and which may retain some contact with water, tend to remain ammoniotelic while reducing excretion rates in order to prevent excessive water loss. Amphibious fish that inhabit environments where emersion is less predictable than the intertidal, can store nitrogen during the state of emersion with some conversion to ureotelism or have been shown to tolerate high ammonia levels in the blood. Finally, the more amphibious fish are more adapted to moving on land and seeing in air. Structural modifications to the pectoral, pelvic, dorsal and anal fins, combined with a well‐developed musculature permit effective support and movement on land. For vision in air, there is a general trend for fish to possess close‐set, moveable, protruberant eyes set high on the head with various physical adaptations to the structure of the eye to allow for accurate vision in both air and water.     

Comparative anatomy of the ciliary body of the West Indian manatee (Trichechus manatus) and selected species

OBJECTIVE: To examine the anatomy of the ciliary body in the West Indian manatee (Trichechus manatus), paying close attention to its vascularization and to compare to those of its distant relative, the African elephant (Loxodonta africana), the amphibious hippopotamus (Hippopotamus amphibius) and the aquatic short-finned pilot whale (Globicephala macrorhynchus). PROCEDURE: Specimens from each species were preserved in 10% buffered formalin, and observed stereomicroscopically before being embedded in paraffin, sectioned and stained by Masson trichrome, hematoxylin and eosin, and periodic acid-Schiff for light microscopic evaluation. RESULTS: The network of blood vessels in the ciliary processes of the West Indian manatee appear to have an intricate pattern, especially with regard to venous outflow. Those of the elephant are slightly less complex, while those of the hippopotamus and whale have different vascular patterns within the ciliary body. Musculature within the ciliary body is absent within the manatee and pilot whale. CONCLUSIONS: In general, there appears to be a direct relationship between the increased development of vasculature and the loss of musculature within the ciliary bodies of the aquatic and amphibious mammals presently studied. Specifically, the ciliary body of the West Indian manatee has a comparatively unique construction, especially with regard to its vasculature.     

基于肠道宏基因组对弹涂鱼两栖适应性的研究

【目的】从基 因组水平上报道两种有代表性的两栖鱼类大弹涂鱼（Boleophthalmus pectinirostris, BP）和大鳍弹涂鱼（Periophthalmus magnuspinnatus,PM）对陆地生活的适应性,以揭示胃肠道微生物群对弹涂 鱼在陆地生活的适应性及其特殊免疫力具有关键作用。【方法】采用 16S 扩增子测序和宏基因组技术,利用两种 有代表性的弹涂鱼和 3 种典型水生鱼类（草鱼 Ctenopharyngodon idellus、鲢鱼 Hypophthalmichthys molitrix 和鳙鱼 Aristichthys nobilis）的宏基因组数据,比较两栖鱼类和水生鱼类肠道的微生物组成、多样性、丰度和功能,并研 究潜在陆生标志微生物群。此外,通过查阅大量文献得到具有代表性的海水鱼类、淡水鱼类、两栖动物和陆生动 物的胃肠道微生物群数据,比较弹涂鱼的肠道菌群组成和功能。【结果】在弹涂鱼的胃肠道微生物群中,厚壁菌门、 变形菌门、拟杆菌门和梭杆菌门占主导地位。这些菌的含量在大鳍弹涂鱼、大弹涂鱼和水生鱼类之间存在显著差 异。草鲢鳙和弹涂鱼二者胃肠道微生物群之间最大的区别是 CKC4 门（一种推测与宿主脂质代谢相关的胃肠道细 菌门类）的比例,草鲢鳙中该比例从 4％ ~27％不等,而在弹涂鱼中则没有发现。此外,弹涂鱼的胃肠道微生物 群中同时具有陆生动物、淡水和海水鱼类以及两栖动物的典型细菌家族,这与它们在水陆过渡咸淡水交界处的生 活特征相吻合。与陆生动物相比,鱼类拥有更高比例的梭状杆菌和变形杆菌,而陆生动物则具有更多的拟杆菌。 在大弹涂鱼和大鳍弹 涂鱼中还发现了此前被认为仅存在于陆生动物的 S24-7 菌株。【结论】推测弹涂鱼胃肠道微 生物群落相比水生性鱼类具有复合和多样性特征,可以通过病原体相关分子模式 PAMP 刺激宿主在进化中形成多 样性更高、拷贝数更多的天然免疫受体基因家族,以此适应更为复杂的两栖生活环境。     

天津市城市景观构成的再创造

“天津——人民津度之港”的文化主题，是实现天津市２０００年总体规划目标的根本动力和基本价值取向。水陆两栖景观序列的空间构成，从总体上描绘了津门生存空间、结构空间和文化空间的历史、现实和未来；与其相应的水陆两栖园林绿化系列等景观序列。体现了社会主义的大津从“河流文化”转向“海洋文化”的灿烂风彩。随着改革开放的深化，一个建筑、桥梁、园林荟萃的新天津必将诞生。     

Eleocharis baldwinii的光合模式鉴定及染色体观察

Eleocharis baldwinii是莎草科(Cyperaceae)两栖类淡水水草,能够在陆地和沉水2种不同的环境下生长。本研究对生长在不同环境的E.baldwinii进行光合模式鉴定,解剖结构观察、C4循环关键酶活性测定以及稳定碳同位素比值测定的结果显示,E.baldwinii的陆生型光合碳同化途径为C4型,而水生型为C3-C4中间型。此外,还对E.baldwinii进行了染色体压片观察,确定其染色体数目为20条。