航天器用超低黏度齿轮泵轻量化设计

为追求航天器用超低黏度介质齿轮泵较好的容积率和较低的发射成本,该文在创建容积率和新重合度公式的基础上,采用最优化设计方法,通过泵的单位排量体积或单位排量质量最小化,实现了90%的最小容积率和质量最轻化,分析了结构参数对优化结果的影响。结果表明:采用齿顶重合度优化设计后的根切重合度为–0.3429,不能保证连续传动要求;压力角、轴半径、齿条刀具齿顶圆角半径和过渡区起始角对优化结果,分别有6.07%、7.8%、2.9%和6.4%的影响,总体上影响不大;径向、轴向间隙的影响很大,并具有0.04、0.07 mm的影响转折点,该转折点为径向、轴向间隙的取值上限提供了依据。初次针对航天用齿轮泵的优化设计尝试,阐明了超低黏度介质同样适用于齿轮泵。该研究可为提高其他行业用超低黏度液压泵的研发提供参考。     

中国水土保持区划——回顾、思考与展望

梳理近70年来中国水土保持区划发展,概述其从定性到定量的方法进步和从单一到复合的体系完善,在此基础上总结其理论框架并提出3个发展阶段。结合统计分析,从理论和实践两方面评价区划实施效果;提出经济管理模型失位、指标体系欠缺和实践衔接不足的3个问题,并以情景模拟和案例介绍提出可能的解决方案。针对水土保持区划发展态势,探究了定性和定量方法在区划中的平衡关系,以及区划在水土保持工作中的定位。期望通过对水土保持区划的系统回顾与讨论,为其未来的发展提供思路。     

数字化奶牛场挤奶机自动清洗控制器的设计

研制出控制功能齐全的挤奶机自动清洗控制器。该控制器采用RS-485标准与上位机通信．选用80C51系列单片机80C552芯片作为CPU，控制器由80C552基本系统、显示、通信、功能键、信号检测和输出控制等部分组成；软件采用C51和VC 语言开发。该控制器可CA实现6种功能：1)整个清洗过程自动完成；2)清洗结束时自动检测清洗质量；3)水温不够时自动报警；4)向上位机传送每班的挤奶量；5)显示清洗过程及时间；6)能够接收上位机控制信号。使用此控制器可以提高生产效率，确保挤奶机清洗干净，同时可实现清洗过程的计算机控制。该控制器可以安装在厅式或管道式挤奶机上。     

产胞外蛋白酶菌株的筛选及环境因素对其产酶活性的影响

采集渔-稻复合系统中的水稻根际淤泥,筛选出有较强产胞外蛋白酶能力的菌株并研究环境因素对其产酶活性的影响。结果显示,通过初筛、蛋白酶复筛等筛选得到一株菌株(编号PRO9);此菌株所产产胞外蛋白酶能够促进水体中有机物质发生氨化反应,减少有机氮含量。此菌还具有产胞外碱性磷酸酶的能力。菌株鉴定结果显示此菌为芽孢杆菌。PRO9菌株所产的胞外蛋白酶在67℃下酶活性最为活跃,最适pH为7,属于中性蛋白酶。     

Size selectivity of diamond and square mesh codends for hairfin anchovy Setipinna taty in Chinese stow net fisheries

ABSTRACT:   Selectivity experiments of diamond and square mesh codends with different mesh size (30, 35, 40 and 45 mm) for hairfin anchovy Setipinna taty were carried out using the covered codend method in Chinese stow net fisheries. In the present study, 5151 specimens were subsampled and asymmetric and symmetric selectivity curves (Richards and Logistic curves) were fitted to the catch data, using the maximum likelihood method according to the SELECT model. The results show that the Richards curve gives a better fit to the selectivity curve for diamond mesh codends with 30, 35 and 40-mm mesh sizes, whereas the logistic curve gives a better fit for the diamond mesh codend with 45 mm mesh size and square mesh codends with 30, 35, 40 and 45-mm mesh size. With the exception of 45-mm mesh size codends, the L ₅₀ of diamond mesh codends were insignificantly larger than those of square mesh codends. However, the selectivity curves of square mesh codends were steeper than those of diamond mesh codends, except the 30-mm mesh size codends. As for diamond mesh codends, according to the linear relationship between the L ₅₀ and mesh size, 36.5-mm mesh size codends could release 50% juvenile hairfin anchovy (below 1-year old). However, diamond mesh codends with such a mesh size are not selective for other species.     

Newly identified C‐type lysozyme in Chinese soft‐shelled turtle (Pelodiscus sinensis) exhibits potent antimicrobial activity

Lysozymes play vital roles in humoural immune response against bacterial invasion by its lytic activity. In the present study, a new C‐type lysozyme was identified and characterized from Chinese soft‐shelled turtle Pelodiscus sinensis. The full‐length cDNA of PslysC was of 923 bp, encoding a polypeptide of 148 amino acid residues. The multiple alignments and phylogenetic relationship analysis revealed the highly enzyme‐related conserved residues. The real‐time PCR analysis suggested that PslysC was constitutively expressed in a wide range of tissues with highest level in blood cells and liver. The expression of PslysC could be significantly up‐regulated under Aeromonas jandaei infection and ammonia exposure, while no significant changes were found under Poly I:C infection. The rPslysC protein was expressed in E. coli and purified by Ni‐NTA. The optimal pH and temperature for rPslysC protein lytic activities were determined at pH 7 and 30℃. rPslysC can inhibit the growth of eight kinds of Gram‐negative bacteria, and three kinds of Gram‐positive bacteria. The binding activity of rPslysC to different microbial polysaccharides and microorganism was analysed. The results showed that rPslysC could bind to selected bacteria, and exhibit a strong binding activity to lipopolysaccharide and peptidoglycan, but a weak binding activity to β‐glucan. This suggests that the binding activity might be the major mechanism of action to realize the antibacterial activity. The present study will provide helpful evidence to further understand the innate immunity of P. sinensis, and the interaction mechanisms of C‐type lysozymes with bacterial membranes.     

杭州城市河道生态治理实践及成效

评估杭州市城市河道生态治理成效,为更好地指导城市河道生态修复工作提供借鉴。后横港、沿山河、新塘河和南大河位于杭州市中心城区,水质都处于劣V类,蓝藻水华和黑臭暴发频繁,从2014年开始,分别开展了一系列生态修复工程。测定氨氮、总磷、高锰酸盐指数、溶解氧指标判断水质改善情况,分析浮游植物、浮游动物、底栖动物判断水体生态修复程度。氨氮后横港下降超过80%,沿山河和南大河下降60%左右;总磷后横港下降接近70%,其他河道下降23%~55%;后横港、沿山河、新塘河高锰酸盐指数进一步降低,部分河道高锰酸盐指数能达到II类水水平;溶解氧浓度都明显上升,均能达到III类以上水平。南大河的浮游植物密度达到了水华暴发的水平;各条河道的原生动物和轮虫类密度都较高,但Shannon多样性指数普遍在1~2;枝角类和桡足类密度偏低;底栖动物Shannon指数均低于1,指示河道处于严重污染状态。杭州市城市河道生态治理工作的中心是:沉水植物恢复及以沉水植物恢复为基础、包含浮游动物和底栖动物等在内全水域生物多样性恢复的生态系统恢复。     

循环水池塘与非循环水池塘中浮游生物的群落结构及其动态研究

研究了循环水对池塘中氮、磷含量、浮游生物种群结构及其相互关系的影响。结果显示:从循环塘中共鉴定出浮游植物93种,隶属6门47属;非循环塘中共鉴定出浮游植物100种,隶属6门48属,循环塘与非循环塘均以绿藻门种类最多,分别占各塘种类总数的40.86%、42%。两塘中浮游植物的密度和生物量分别为:循环塘为247.68～1133.31(×104ind/L)和3.07～10.83 mg/L;非循环塘为511.68～1773.3(×104ind/L)和4.48～17.34 mg/L。循环塘浮游植物的密度和生物量比非循环塘要低,且差异性显著(P<0.05)。循环水鱼塘中共检出浮游动物33属42种,非循环水池塘68属88种,在试验期间两塘中浮游动物的优势种主要是由原生动物和轮虫组成,其种数变化顺序为原生动物>轮虫>枝角类和桡足类。循环塘中原生动物和轮虫分别占浮游动物总种类数的52.38%、33.34%;而非循环塘中原生动物和轮虫分别占浮游动物总种类数的42.05%、48.86%。其中循环塘72～708.11 ind/L和0.41～1.69 mg/L;非循环塘152.9～208.20 ind/L和0.26～0.46 mg/L。循环塘浮游动物的密度和生物量显著高于非循环塘(P<0.05)。循环塘与非循环塘中浮游植物的Shannon-Wiener指数分别为介于1.39～1.62和1.16～1.48之间,两塘中浮游动物的Shannon-Wiener指数分别为介于0.50～1.95和1.08～1.45之间。结果表明:循环水对养鱼池塘水体中浮游生物的出现率、丰度和生物量影响较大。     

豆粕替代鱼粉对点篮子鱼生长性能的影响

以豆粕替代鱼粉配置5组等氮(35%)等能(19.00 MJ/kg)饲料,豆粕∶鱼粉替代比分别为0∶1(D₁)、1∶2(D₂)、1∶1(D₃)、2∶1(D₄)、1∶0(D₅),研究豆粕蛋白对体重(104.64±2.76) g点篮子鱼生长性状、体成分、生物学指标的影响,从而确定点篮子鱼饵料中最佳的动植物蛋白比。试验在室内圆锥形孵化桶中进行,分5个处理,每个处理3个重复,每个重复25尾鱼。49 d养殖试验结果表明,饲料中豆粕含量对点篮子鱼生长有显著影响,特定生长速率(SGR)、增重率(WG)、摄食率(FI)与替代比成负相关,对照组(D₁)［11.87(100 g)/d］FI显著高于全豆粕组(D₅)［5.81(100 g)/d］。饲料系数(FCR)与替代比成正相关,D₅组FCR高达2.97。饲料中豆粕含量水平对肌肉粗蛋白与水分含量无显著影响,对全鱼粗蛋白和脂肪影响显著,粗蛋白在D₅组取得最小值19.11%。肝脏蛋白含量随饲料中豆粕含量增加呈先增加后降低趋势,高豆粕含量组肝脏脂肪含量显著低于低豆粕组。蛋白替代对点篮子生物学指标影响较小。综合考虑SGR、FCR、FI等指标,点篮子鱼饲料中豆粕替代鱼粉比不宜大于1∶2。但从肌肉营养品质方面考虑,替代比可以达到2∶1。     

油茶科技示范观光园规划设计--以江西星火油茶科技示范园为例

林业科技示范园作为现代林业发展的新型模式,有促进林业产业发展的作用。本规划园利用项目地现有的优势条件将园区打造成以“油茶”为主题的专类科技示范观光园,园区共有油茶生态景观文化、茶园休闲娱乐、油茶科技实验示范等3个分区,将园区建成景观、文化、科技、休闲等多功能于一体的油茶高新技术产业基地,促进油茶文化的传播,为全省乃至全国油茶产业发展提供示范引领作用。