Engineered-airlift pumps for aquaculture applications using multiphase flow analysis

Currently, very few aquaculture operations are employing airlift pump technology for water recirculation, aeration, and waste removal. This is likely due to the poor design and lower efficiency of traditional airlift design, the limited amount of research effort that has been invested in improving performance capabilities of air lift pumps and the general lack of awareness of the industry about the inherent advantages of airlift systems. A new efficient airlift pump is hydrodynamically designed by incorporating the Volume of Fluid (VOF) multi-phase model along with the K-ε turbulence model utilizing Computational Fluid Dynamics (CFD) tools. The pump is designed to offer a substantial reduction in total energy usage as well as an improved quality of the culture products in order to make it attractive to aquaculture industry. In this study, both numerical and experimental investigations were carried out for airlift systems operating under two different submergence ratios of 50% and 90% in a lab setting using 2.54 cm diameter pumps. Also, the performance of a large-scale pumps of 10.16 cm diameters were also tested in an aquaculture raceway to determine its effect on the operation. The numerical results were found to be in agreement with the experiments within ±20% which is considered very reasonable for multiphase flow analysis. The present study was found to present a great tool for modelling the airlift pump performance, and potentially proposing new designs.     

Are dual-purpose and male layer chickens more resilient against a low-protein-low-soybean diet than slow-growing broilers?

ABSTRACT

1. Although fattening dual-purpose types or male layer hybrid chickens appears more ethical than the common practice of culling day-old male layer chicks, the lower feed efficiency of these birds raises concerns. Replacing feed ingredients that compete with food production by those of lower value for human nutrition would be beneficial.

2. Lohmann Dual (LD), a modern dual-purpose type, Lohmann Brown (LB), a male layer hybrid, and Hubbard JA 957 (HU), a slow-growing broiler type, were fattened for nine weeks on two diets (control or ?20% crude protein; n = 6 × 12 birds). Growth, carcass and meat quality were analysed.

3. Growth performance of HU exceeded that of LD and especially of LB. The growth depression caused by the low-protein diet fed to LD (?7%) was only half of that found in HU (?13%). The LD fed the control diet had the same feed efficiency as the HU fed the low-protein diet. Even the LB had a lower performance and feed efficiency with the low-protein diet in growth. There was a gradient in carcass properties (weight, dressing percentage, breast meat yield, breast proportion and breast angle) from HU to LD to LB, with some additional adverse effects of the low-protein diet especially in HU. There were some breed differences in fatty acid profile in the intramuscular fat.

4. In conclusion, the dual-purpose type used complied with regulations for Swiss organic poultry systems in terms of growth rate and was found to respond less when fed a low-protein diet than the slow-growing broiler type. The LB males were inferior in all growth and carcass quality traits. Future studies need to determine the exact protein and amino acid requirements of dual-purpose and layer hybrid chickens and the economic feasibility of the systems, especially for organic farming.     

电控喷油对降低双燃料内燃机烟度排放的试验研究

介绍了电控LPG-柴油双燃料内燃机供给系统的设计,柴油分别采用机械泵和电磁铁执行器供给,LPG采用电控顺序喷射方式供给。同时对控制系统进行了硬件和软件设计,对软件的功能进行详细的说明,最后对双燃料内燃机进行标定试验,论证了柴油的电控喷射对降低烟度排放的影响。     

Dual RNA-seq技术及其在宿主-病原体相互作用中的研究进展

利用转录组测序技术(RNA-sequencing, RNA-seq)进行转录组分析是了解病原体入侵宿主分子变化的重要工具,在同时分析病原体与宿主转录组时,RNA-seq技术需要分别构建病原体及宿主的cDNA文库,再将其各自映射到病原体及宿主参考基因组中,而互作转录组测序技术(Dual RNA-seq)无需分离两物种,只需构建一个转录组文库,便能同时对两个(或多个)研究对象进行测序和分析,可以直观地揭示病原体和宿主相互作用过程中转录组学动态变化,因此Dual RNA-seq技术被广泛应用到人类疾病和生物感染模型的相互作用研究中。为了解Dual RNA-seq技术及其在宿主-病原体相互作用研究中的前景,就Dual RNA-seq技术概述以及近年来该技术在原核生物、真核生物以及病毒研究中的应用现状及发展前景进行综述。Dual RNA-seq技术可为病原体与宿主相互作用的研究提供新视角,有助于更好地识别和理解感染过程中病原体和宿主的转录组学变化,从而揭示潜在的新靶点或生物标记物。     

IPv6和IPv4的共存与过渡及其应用

分析了IPv4向IPv6过渡的技术,指出了IPv6在农业信息化中的广阔应用前景.     

水稻两用核不育系育性转换光温反应型的分类研究

 在人工控制的9种光温处理下，对76份水稻两用核不育系的育性转换光温反应进行了研究。根据自交结实率的光周期效应、温度效应和光温互作效应的分析，供试的两用核不育系中，占96%的不育系的育性转换光温反应型可归为以下3种：（1）光周期敏感不育型，其统计学特征是育性转换的光温互作效应和光周期效应显著而温度效应不显著；（2）温度敏感不育型，其统计学特征是育性转换的温度效应显著而光周期效应不显著、光温互作效应显著或不显著；（3）光温互作不育型，其统计学特征是育性转换单独的光周期效应和温度效应不显著，仅光温互作效应显著。在供试的粳型不育系中，有34.8%、13.0%和47.8%的材料分属上述3种光温反应型;在供试的籼型不育系中,有73.6%和22.6%的材料分属温敏型和光温互作型,没有一份材料为光敏型。结果表明现有的两用核不育系育性转换光温反应是多型性的。文中还对实用性籼型两用核不育系育性转换光温反应型的选择问题作了讨论。     

对偶模型在畜禽饲料配方优化设计上的应用

 在一般线性规划配方模型基础上通过引入其对偶线性规划问题 ,以求解参与优化计算的养分项目即资源的影子价格。在配方优化设计领域 ,养分资源的影子价格揭示了当增减参与计算并希望最终达到的养分指标时对最终饲粮成本的影响程度。某一资源影子价格的值越大 ,表明其对配方的最低成本影响越突出 ;而影子价格为“零”的养分指标是指其在特定取值范围内 ,该指标的达成对最低成本不构成影响 ,同时笔者还讨论了今后我国饲料配方技术研究的深层次发展方向     

氟苯尼考双混悬型乳剂的体外药效学研究(英文)

[目的]为了探明氟苯尼考双混悬型乳剂的体外药效学特征。[方法]以氟苯尼考注射液为对照组对氟苯尼考双混悬型乳剂进行5种细菌的最低抑菌浓度(MIC)、最低杀菌浓度(MBC)和耐药突变选择窗(MSW)的测定,对鼠伤寒沙门氏菌进行抗生素后效应(PAE)和抗生素后亚抑菌浓度效应(PASME)的测定。[结果]相对于普通注射液氟苯尼考双混悬型乳剂对5种细菌的MIC和MBC无明显变化,但其明显缩小了对5种细菌的MSW(P<0.01),并且明显的延长了对鼠伤寒沙门氏菌PAE和PASME(P<0.01)。[结论]氟苯尼考双混悬型乳剂在体外能够减小细菌耐药几率,明显延长抗生素对细菌的后效应时间,从而有效地提高抗菌效果。     

冬小麦双覆条播试验初报

试验表明,双覆条播与常规露地条播相比,当季增产率为１６．４８ ％ ,潜在增产率为１１ ．５８ ％ ,理论增产率为２８ ．０６％ ,而且增强了小麦根系生长,地膜还可被下茬作物再利用。     

双向端平阀在前装载拖拉机上的应用

由于拖拉机的发动机前置,使得传统装载机上应用的反转六连杆机构在拖拉机上难于布置。为了满足前装载拖拉机的铲斗在提升动臂过程中保持平移,只有采用平行四边形连杆机构或者液压自动端平阀,依靠端平阀自动地控制铲斗油缸的运动来使铲斗保持水平状态。