Vaccination of pregnant cows with K99 antigen of enterotoxigenic Escherichia coli and protection by colostrum in newborn calves

The immune response to the K99 was tested in 45 pregnant cows, subcutaneously vaccinated, for protecting the newborn calves. Serological tests were performed in the blood sera of all animals and in the milk and colostrum sera; hemogram, inhibition of the adhesion to the brush border and histological tests were performed. The calves from vaccinated cows survived the experimental infection after the suction of colostrum in spite of the fact that the calves from control dams died with diarrhea.     

基于WBS的碾压式土坝填筑质量控制要点探讨

对任何工程项目来说,质量都是决定项目成败的关键,而水利工程受水文、地质等条件影响,质量问题更加复杂多变,难以控制.本文正是针对于此,利用WBS对某碾压式土坝填筑工程进行结构分解,使整个工程的质量控制活动变得条理化.     

Design characteristics of pooled circular stepped cascade aeration system

Aeration experiments were conducted in a brick masonry tank of dimension 4 m × 4 m × 1.5 m to study the design characteristics of pooled circular stepped cascade (PCSC) aeration system. Based on dimensional analysis, non-dimensional numbers related to geometric, dynamic and process parameters were proposed. The non-dimensional geometric parameters – number of steps (N), ratio of total height of cascade (H) to the bottom radius of cascade (R_b), % coverage of circumference of each step by enclosure (P_e) and number of enclosures in each step (N_e) were optimized. Maintaining the optimized geometric parameters (N = 6, H/R_b = 0.25, P_e = 20% and N_e = 9), aeration experiments were further conducted at different discharges (Q) to develop simulation equations for prediction of aeration characteristics of PCSC aeration system at different dynamic conditions. Simulation equations for oxygen transfer and power consumption based on Froude (Fr) criterion were developed subject to 0.0014 ≤ Fr ≤ 0.0144. SAE of the developed prototype PCSC aerators based on estimated brake power ranged between 2.43 and 3.23 kg O₂/kWh.     

NUMERICAL ANALYSIS OF CASCADE FLOW FIELD IN TURBOMACHINES BY BOUNDARY ELEMENT METHOD ENTIRELY

In order to compute the incompressible plane cascade flowfield in turbomachines with nothing but the Boundary Element Method, thispaper presents a numerical method by which both the velocity potentials andthe tangential velocities along the surfaces of cascade profile are computed by the Boundary Element Method, and because of this method, good results are obtained.     

淤地坝系风险预警防控平台研究与应用

[目的] 研究在极端降雨条件下淤地坝系的风险预警防控问题,实现智能巡检,防止淤地坝发生水毁溃决,为防汛管理和风险预警提供专业、快速、精确的技术支持。[方法] 基于iVX语言,使用MySQL数据库,采用“家谱法”理论和淤地坝系溃决风险分析程序FT-IWHR,结合工程实际,通过功能模块的设计与开发形成全覆盖、高效率软件系统。[结果] 建立了淤地坝系风险预警防控平台,以可视化、移动化的方式将淤地坝系基础信息、巡检监测系统和溃决风险预警系统应用到淤地坝系的日常风险管理中。该平台在山西省临汾市乡宁县西廒沟小流域得到应用。[结论] 通过信息化建设对淤地坝系进行风险预警防控是可行的。它可以提供快捷直观的信息传递平台,方便工作人员对淤地坝进行运行管理,有效预防淤地坝系发生风险事故。     

利用LNG梯级冷能的冷库系统构建与载冷剂选择

分析了LNG冷能的梯级利用方式,对LNG冷能冷库系统从工艺角度进行设备、流程的研究,并作载冷剂选择.以LNG冷能评价分析指标,对某小型LNG冷能利用项目进行了经济性计算.结果表明：与常规电动压缩式冷库相比,在考虑设备造价与折旧率的情况下,以运行费用减少折算的冷库系统投资回收期仅为1.11年.因此,LNG冷能的第三级用于低温冷库是合理的冷能利用方式,既可以简化冷库系统的结构,减少设备投资费用,又能回收大量的LNG冷能,明显降低冷库运行的电耗,具有较高的节能经济性.     

Warming favours small-bodied organisms through enhanced reproduction and compositional shifts in belowground systems

The increased prevalence of smaller-bodied species under warmer conditions (community downsizing) is hypothesized as an ecologically critical consequence of climate change, leading to changes in trophic transfer efficiency, and rates of nutrient and energy flux within ecosystems. This study used 100 intact peat-soil mescosms to measure changes in belowground biodiversity under three manipulated climate variables: elevated temperature, elevated CO₂, and altered water table. Changes in species richness, abundance, community composition and body size spectra were used to determine whether climate change factors led to community downsizing, and elucidate any underlying mechanisms. Warming was the primary driver of compositional shifts in belowground fauna communities with the strongest effect among the smaller-bodied, non-sexually reproducing species. Increases in abundance driven by enhanced reproduction in small-bodied species rather than an increased extinction-rate among large-bodied predators was the basis of the observed downsizing. The overall consequences of warming-induced changes in belowground systems on ecosystem function are still unclear. However, as body size is intricately linked to metabolism, observed community downsizing suggests reductions in food web trophic transfer efficiency with consequences for nutrient and energy dynamics in belowground systems.     

双平板叶栅绕流的流动结构及其激励特性研究

绕流叶片的非稳态流动及其尾迹涡结构是诱发水力机械振动的主导因素。以横向布置的一对平板叶栅为研究对象,基于LES计算雷诺数在4.8×104下的三维绕流流场,分析绕流流场涡演化结构、升阻力及压力脉动等特性,以揭示尾迹干涉下平板绕流的流场结构及其激励机制。结果表明:该雷诺数下,单平板绕流平板表面存在错列布置的发卡涡结构,绕流尾迹呈现出高度的三维特性;双平板叶栅绕流状态下,上、下游平板间的间隙流动结构有明显抑制上游平板表面涡结构演化的作用;平板受力在模式H和模式L之间不断切换,且升力波动的幅值随阻力的增大而增大,尾迹干涉下下游平板受力的模式切换频率升高,升力波动幅值也增大;平板表面压力脉动的主要激励源为平板尾涡脱落。尾迹干涉下平板绕流及受力分析,可为水力机械叶片尾迹干涉下的流动主动控制提供参考。     

高压内反馈串级调速系统在油气集输中的应用

高压内反馈串级调速系统是一种具有良好性能价格比的调速节能设备，通过在辽河油田油气集输中的应用，证明该设备能满足许多场合的高压电动机调速需求，该设备运行效率高，操作简单，易于维护，是国内现阶段一种较理想的节电设备。     

Nutritional parameters in the blood of dams during late gestation and immediately after calving,in the umbilical vein at calving,and in the blood of calves immediately following birth in Holstein heifers pregnant with either Holstein or beef breed fetuses

Dairy cattle management lacks consideration of fetal breed, the effect of which on fetal growth and nutrition are unclear. We investigated blood parameters in 12 late-pregnant Holstein heifers with similar (Holstein, n = 5) or different (Japanese Black [n = 4] or F1 cross [n = 3]; Holstein × Japanese Black) fetus breeds and in their umbilical cords and calves. Samples were obtained from dams 1 week before calving (−1 week) and immediately after calving, from the umbilical vein at calving, and from calves immediately after birth. Dams with beef fetuses had higher serum glucose levels (−1 week; p < .05) than those with Holstein fetuses. Plasma total amino acid, total essential amino acid, total nonessential amino acid, and other amino acid concentrations were lower in the umbilical veins of dams with calves of the beef breeds than in those of the Holstein breeds (p < .05). Furthermore, serum glucose and plasma amino acid levels were lower in the beef calves than in the Holstein calves (p < .05). Overall, nutrient supply from dams to beef fetuses was lower than that to Holstein fetuses. Our findings may facilitate feeding management of dairy cattle pregnant with beef breeds for appropriate fetal growth and nutrition.