Effects of dietary Bacillus pumilus on growth performance,innate immunity and digestive enzymes of giant freshwater prawns (Macrobrachium rosenbergii)

The present study was conducted to investigate the effects of Bacillus pumilus on the growth performance, innate immunity and digestive enzymes of the giant freshwater prawn, Macrobrachium rosenbergii. Prawns (mean weight: 1.81 ± 0.01 g) were fed different levels of B. pumilus at doses of 0, 1 × 10⁷, 1 × 10⁸ and 1 × 10⁹ CFU/g to produce one control group and three experimental groups (G1, G2 and G3), respectively. After a 60‐day experimental feeding period, the results showed that the final weight, weight gain rate (WGR) and specific growth rate (SGR) were significantly higher in experimental groups than in the control (p < 0.05), whereas these improvements did not differ significantly (p > 0.05) among experimental groups. The improvements in phagocytic activity, respiratory burst (RBs) activity and the activity of catalase (CAT), nitric oxide synthase (NOS) and acid phosphatase (ACP) were significantly higher in G2 and G3 than in the control and G1 (p < 0.05). Further, the activity of CAT, NOS and ACP significantly increased with an increase in the dietary level of B. pumilus (p < 0.05). The activity of phenoloxidase (PO) in G3 was significantly higher than that in the control (p < 0.05). The activity of amylase was significantly higher in the groups G2 and G3 than that in the control group. G3 improved the activity of protease compared with the control (p < 0.05). In conclusion, the results of this study indicated that the potential use of B. pumilusat a dose of 1 × 10⁸ CFU/g feed could improve the growth, immunity and digestive enzymes of M. rosenbergii.     

Analysis of sinking death using video images of the swimming performance of Pacific Bluefin tuna (Thunnus orientalis) larvae

In this study, we aimed to clarify the mechanism of sinking death during the larval stage of Pacific Bluefin tuna Thunnus orientalis by investigating the effects of swimming performance on sinking death, using a behavioral approach. Swimming performance was examined 3–9 days after hatching (DAH) under day and night light conditions in cuboid experimental tanks. Swimming behavior variables such as swimming speed and swimming angle were measured under both light conditions. Larvae in the daytime experiment and larvae with inflated swim bladders at night were distributed on the surface layer of the water column. In contrast, larvae with uninflated swim bladders at night were frequently observed swimming vertically or sinking to the bottom of the tank. Larvae with inflated swim bladders at night were always distributed beneath the surface until the next morning (survival rates were 100 %). However, larvae with uninflated swim bladders at night swam upward repeatedly and later sank to the bottom of the tank (survival rates were 60 % and 38 % at 5 and 9 DAH, respectively). Larvae with uninflated swim bladders were not always able to maintain their swimming depth by swimming until the next morning. Additionally, their swimming speed and vertical swimming frequency (ratio) depended on the illumination and swim bladder conditions. Our findings show that larvae with uninflated swim bladders at night were associated with a higher risk of sinking death. The swimming energy capacity of Pacific Bluefin tuna larvae, which indicates the total amount of the energy that enables individuals to swim throughout the night without feeding, was found to be linked to sinking death.     

1047年北宋宫廷祈雨的诸相

本文以1047年发生在北宋宫廷内的一场祈雨祭祀为研究对象,运用"剧场国家"理论,描绘了祈雨的"展演"相与"权力"相,研究了祈雨期内以展演为表征、以权力为暗流的人神、人地、人人关系。研究发现:一方面,祈雨是充满象征意义的展演式活动,祈雨人宋仁宗需要向天神与黎民展演德行,而展演德行又需借助于气象技术;另一方面,贾昌朝被罢相是多重因素作用下的结果,罢相反映出北宋中期朝廷内激烈的政治纷争,其仍为庆历新政后权力博弈的延续。可见这场祈雨是一场德行的展演,也是实在的操纵帝国的权力之争。     

基于Cruise的纯电动汽车的参数匹配与仿真

对某款纯电动汽车的驱动电机参数、传动系统参数、电池组参数等进行参数匹配选型,并借助汽车仿真软件AVL Cruise(Cruise是一款在业界功能最强大、最稳定,适用性最广的整车和传动系统性能分析的仿真工具)进行动力性能仿真分析。经过仿真验证之后,该参数匹配过程正确,动力性能达到设计的要求。     

角钢⁃集成材L形组合柱的受压性能研究

为提高装配式木结构中异形柱的力学性能,设计了一种用热压等边角钢和SPF集成材为原料,环氧树脂胶黏剂连接制作的角钢-集成材L形组合柱,作为框架结构或框架剪力墙结构的角柱。以角钢边宽度对L形柱正截面承载力的影响进行了轴压试验研究,并进行ANSYS有限元模拟,以判断模拟预测的准确性。结果表明:角钢-集成材L形组合柱相对于同截面面积的木柱而言承载能力上升37.0%~51.4%,刚度上升36.5%~72.8%,同时L形柱有良好的延性;适当增加L形柱中的角钢边宽度可以使承载能力有效提高,但是其短边处的集成材易产生破裂,增加试件的脆性破坏;集成材之间的环氧树脂胶合界面在破坏前后都性能良好,在材料弹性阶段钢材和木材有效共同受力,承载力计算时需要考虑钢材的塑形增强作用;ANSYS有限元模拟的角钢-集成材L形组合柱弹性模量结果和试验结果一致,误差在10%以内,模拟结果基本可靠。研究成果对于预测角钢-集成材L形组合柱在实际预制装配时的安全可靠性提供了理论依据。     

淀粉与油脂对妊娠母猪糖脂代谢及其繁殖性能影响的研究进展

妊娠后期随着胎儿生长速度和乳腺发育加快，母猪机体代谢强度逐渐增加，机体糖脂代谢失衡，出现代谢紊乱。能量占整个日粮成分的70%以上，选择适当的日粮能量来源以调节糖脂代谢的平衡是提高母猪繁殖效率的有效方法。淀粉与油脂作为母猪日粮主要能量来源，均可显著影响后备母猪的初情期启动或经产母猪的繁殖性能，但以母猪本身的糖脂代谢特征为出发点，评述不同来源与水平的淀粉或油脂对母猪繁殖性能的影响鲜有总结报道。文章首先综述了母猪妊娠期糖脂代谢特点和代谢机制，简述了妊娠期代谢紊乱对母猪繁殖性能的不良影响，介绍了淀粉与油脂在母体的吸收及代谢特点，对比分析了不同水平与来源的淀粉和油脂对母猪产仔性能和泌乳性能的影响。最后，为最大化提高猪场经济效益，根据实际生产目的，总结了选择合适能量来源的依据。该综述旨在选择日粮适宜水平和来源的淀粉和油脂以期为提高母猪繁殖效率提供数据支持和理论指导。     

河朔荛花根中抑菌活性成分研究

在活性追踪指导下，采用多种分离技术从河朔荛花根甲醇提取物中分离得到12个化合物，经核磁共振波谱、质谱等技术并结合相关文献确定其结构分别为1-己酸-2,3-硬脂酸甘油三酯( 1 )、β-谷甾醇( 2 )、月桂醇( 3 )、顺-十八碳-9-烯酸( 4 )、(2E)-庚基-3-(3, 4-二羟基苯基)丙烯酸酯( 5 )、(–)-pluviatolide( 6 )、1β-hydroxy-10β-H-guaia-4,11-dien-3-one( 7 )、异狼毒素( 8 )、新狼毒素B( 9 )、瑞香酚( 10 )、单棕榈酸甘油酯( 11 )和(+)-去甲络石甙元( 12 )。其中，化合物 3 、 4 和 6 ~ 12 均为首次从河朔荛花中分离得到。抑菌活性测定结果表明:异狼毒素( 8 )和新狼毒素B( 9 )对马铃薯晚疫病菌Phytophthora infestans菌丝生长和孢子萌发均表现出明显的抑制作用，其中对菌丝生长的EC₅₀值分别为68.4 μg/mL和44.9 μg/mL，对孢子萌发的EC₅₀值分别为25.1 μg/mL和14.0 μg/mL。     

Effects of chromium yeast,tributyrin and bile acid on growth performance,digestion and metabolism of Channa argus

A 60‐day feeding trial was carried out to evaluate the effects of chromium yeast (CY), tributyrin (TB) and bile acid (BA) on the snakehead (Channa argus). The control (CT) group was fed the basal diet, and the experimental groups were fed 200 mg/kg CY (concentration: 1,000 mg/kg), 2.5 g/kg TB (purity: 45%) or 1 g/kg BA (purity: 30%) in addition to the basal diet. The addition of CY, TB and BA statistically increased the weight gain rate, and specific growth rate, whereas the feeding rate and feed conversion ratio were significantly reduced (p < 0.05). When compared with the CT group, TB elevated the serum glutathion peroxidase (GSH‐Px) activity; and BA reduced low density lipoprotein cholesterol (LDL‐C) contents significantly (p < 0.05). The three feed additives reduced intestinal malonaldehyde (MDA) levels dramatically. Tributyrin significantly enhanced intestinal trypsin and pepsin activities (p < 0.05). The activity of fructose‐1,6‐bisphosphatase and pyruvate carboxylase in the group fed CY was significantly lower than in the CT group. In conclusion, dietary inclusion of the three additives enhanced growth performance of C. argus. Dietary supplementation of CY affected protein, glucose and lipid metabolism. Diets with TB levels improved intestinal digestive enzyme activity and antioxidant capacity. The addition of BA improved glycolipid metabolism.     

玉米免耕播种机漏播补偿方法对比研究

为解决玉米免耕播种机播种作业时存在漏播的问题，针对漏播自补偿和漏播辅助补偿方法进行了对比研究。对水平圆盘排种器的排种性能进行试验，获取了排种器在不同排种盘转速和播种粒距下排种合格指数、漏播指数和重播指数。由漏播自补偿补种性能分析可得，在排种口检测漏播信号进行加速补种，补种的实际粒距LPR>1.5L，补种粒距依然为漏播，无法实现漏播补偿功能，若在种子脱离排种口之前检测到漏播信号，提前做好加速准备再进行补种，可实现漏播自补偿功能。由漏播自补偿试验可知，漏播自补偿受播种速度和播种粒距影响较大，在播种粒距为20、25cm，播种速度不大于5km/h时，补种合格率不小于88%，在播种粒距为15cm或播种速度大于5km/h时，补种合格率较低；由漏播辅助补偿补种性能试验可知，在播种速度3~7km/h，粒距15~25cm下，补种成功率不小于89%，在播种速度不大于5km/h，补种合格率不小于96%。为了保证补种位置精确，采用漏播辅助补偿装置进行补种，〖JP2〗需合理设计漏播补偿装置安装位置，同时受播种速度、播种粒距、排种盘线速度、投种角的影响，通过合理设计补种装置安装参数后，控制补种装置响应时间t和补偿装置排种盘的线速度vb实现补种位置的精确控制。     

间作模式下小麦联合收获机清选装置CFD-DEM气固耦合仿真与试验验证

为了提高间作模式下小麦联合收获机清选性能，研究旋风分离筒内流场和颗粒的运动状态，探索分离筒的最佳工作参数组合，运用离散元法和计算流体力学耦合的方法分析了气流与颗粒的相互作用，以喂入速度、吸杂压强、筒体高度、下椎体角度为试验因素对清选过程进行了仿真正交试验，对最佳清选参数组合完成了田间试验验证。结果表明:气流在分离筒内形成内、外旋涡，内漩涡的运动使短茎秆进入吸杂管道，籽粒在外旋涡的作用下滑落到集粮盘；仿真试验的最佳参数组合为喂入速度12 m·s^-1吸杂压强-1 800 Pa、筒体高度350 mm、下椎体的角度65°，得到的清洁率和损失率分别为92.18%和1.99%，与田间试验的误差分别为2.947%和7.428%。