Influence of agricultural adjuvants on droplet spectra

The formation of a spray is the result of interaction between the nozzle type and the spray liquid. When adjuvants lower the surface tension, a shift to a finer spray quality might be expected. Increases in viscosity might cause coarser sprays. The spray pressure, nozzle type and spray liquid determine spray performance. Adjuvants that cause droplets of oil in the spray mixture, for example crop oils, petroleum oils and even some water-insoluble emulsifiers and surfactants, may unexpectedly increase the spray droplet size. In cases where a finer spray is obtained, the volume fraction of drops smaller than 100 microm diameter, V(100), is expected to increase, but for some adjuvants a decrease in V(100) is observed. Finally, spray droplets may also differ when the concentration of the applied adjuvants changes. An overview based on reports in the literature is given of the effects of different classes of adjuvants used for agricultural cropping on spray droplet spectra. The effects of these adjuvants on spray formation depend on the type of nozzle in combination with the applied pressure.     

Theoretical and Experimental Analysis of Spray Flow and Evaporation in Sprinkler Irrigation

This paper shows the main results,reached during the last three years ofresearch by this group, on sprinklerirrigation modeling and experimenting. Amathematical method based on the SecondPrinciple of Dynamics proves to fully matchthe results obtained by more complicatedmodels from other authors, but still needsfurther verification to determine aerialwater droplet evaporation, even if this nowhelps to confirm the relevance of airfriction in the process. The experimentalactivity performed also shows its use inhelping towards a fuller understanding ofwater waste in sprinkler irrigationpractice.     

不同侧风和静电电压对静电喷雾飘移的影响

为研究不同侧风和静电电压对静电喷雾雾滴飘移的影响规律,设计不同侧风(恒速风1、2、4 m/s及0~4 m/s变化的模拟自然风)及静电电压(0,2,4,6,8 k V),进行喷杆式静电喷雾机的雾滴飘移试验,测定不同静电电压下的雾滴粒径与荷质比,并对比分析雾滴飘移质量中心距和飘失率。结果表明:随着静电电压的增大,雾滴粒径减小,雾滴荷质比增大,0~8 k V电压下电极干燥和电极打湿对雾滴荷质比没有显著影响。在侧风风速为1 m/s时,0~8 k V静电喷雾的雾滴飘移中心距小于0.55 m,雾滴飘失率低于15%。在侧风风速2 m/s时,非静电喷雾的雾滴飘失率为11.9%,6~8 k V静电喷雾的雾滴飘失率超过20%,其中静电电压8 k V的雾滴飘失率(23.9%)比非静电喷雾增加100.8%。在侧风风速4 m/s时,4~8 k V静电喷雾的雾滴飘移中心距在0.9 m以上,雾滴飘失率在30%以上,其中静电电压8 k V下的雾滴飘移中心距为967.2 mm比非静电喷雾下增加了13.7%,雾滴飘失率为35.4%比非静电喷雾下增加了59.5%。相同静电电压下,2 m/s的恒速风和0~4 m/s变化的模拟自然风之间对雾滴飘失率无显著差异。该研究为优化喷雾技术参数和提高雾滴抗飘移的能力提供参考。     

果树喷雾机防风罩对喷雾射程的影响

在对果树施药中，为减少风力因素导致的雾滴漂移，经济而有效的方法是采用防风罩。该文对防风罩进行研究与设计，制作了6种防风罩。针对防护罩防风效果，在密闭实验室条件下进行喷雾试验，选用日本池内公司生产的两种喷头；喷头移动速度为：0.51、1.21、1.91、2.60、3.30、4.00 km/h；试验的内容包括喷雾射程和雾滴的沉积均匀度。试验结果表明：两种喷头在不同速度下采用防风罩＃4时的喷雾射程比采用其他防风罩和无防风罩时分别平均提高了1.3%～13.2%和9.1%～17.3%。     

冷风机雾滴分布特性试验研究

为了探讨喷雾冷风机这一新型降温措施的雾滴分布规律，为冷风机的开发和应用提供依据，利用激光雾滴测定仪对不同叶片数、不同供水量下冷风机的喷雾性能进行了试验研究。结果表明：喷雾冷风机不需要高压泵和喷头，在自来水常压下供水即可取得良好的雾化效果，雾滴直径在质量上呈现正态分布，90％以上的雾滴直径均小于50 μm；相同供水量下，四叶片比两叶片冷风机雾滴直径小10 μm左右，四叶片比两叶片冷风机喷雾量大，且喷雾效率高 25%～47%。     

蒸发式过冷水制冰液滴蒸发结晶的模拟

蒸发式过冷水制冰系统中液滴传热传质特性研究具有重要意义。为了分析蒸发式过冷水制冰系统中液滴的热质传输特性,该文将单个液滴冷却结晶过程分为全液相区、固-液两相区和全固相区3个不同区域,建立液滴在大空间内蒸发降温结晶过程的数学模型,通过数值求解方法研究其在大空间蒸发室内降温结晶过程的温度变化特性,进一步分析液滴和空气的入口参数与液滴整个蒸发结晶特性的关系,为蒸发式过冷水制冰系统的结构优化设计和运行管理提供参考依据。     

Impact of short-term high-fat feeding on lipid droplet content in mouse oocytes

Mature mammalian oocytes contain lipid droplets (LDs), which are neutral lipid storage organelles critically important for energy metabolism. In mice, maternal obesity, induced by long-term (> 3 months) high-fat feeding, contributes to the accumulation of LDs in mature oocytes. However, few studies have investigated the influence of short-term high-fat feeding on LD content. In this study, we demonstrated that 3 weeks of high-fat feeding is sufficient to increase LD content and intracellular triacylglycerol levels. Using a two-step centrifugation technique to release LDs into the perivitelline space, we found that short-term high-fat feeding increased the level of LDs in MII oocytes and that 3 days of high-fat feeding were sufficient to increase efficiency of LD release. Collectively, our study suggests that short-term high fat feeding can have a higher impact on lipid metabolism during oocyte maturation.     

带电雾滴速度场理论研究

从理论上建立了气流与带电雾滴速度关系式。由欧拉法和拉格朗日法建立了确定性带电雾滴速度场、带电雾滴速度驻值线方程和由随机微分理论建立的带电雾滴速度随机模型,使两相流动有了初步的理论模型,还建立了喷头结构参数和雾滴速度关系式,将为控制流场和选择合理的喷头参数提供依据。     

不同乳脂率德宏奶水牛乳腺组织脂滴形成相关基因的表达研究

本研究旨在探索脂滴形成相关基因嗜乳脂蛋白(BTN1A1)、黄嘌呤脱氢酶(XDH)、围脂滴蛋白1(PLIN1)和PLIN2在不同乳脂率德宏奶水牛乳腺组织中的表达差异。试验选取同一养殖小区的健康德宏奶水牛216头,采集乳样,用乳品分析仪测定乳脂率。根据乳脂率测定结果,分为低乳脂率组(L组,<7.0%)、中乳脂率组(M组,7.5%±0.5%)和高乳脂率组(H组,>8.0%),每组选取第2胎、年龄相近、处于泌乳中期的德宏奶水牛各3头,采集乳样,进行乳脂率测定;屠宰后采集乳腺组织,提取总RNA,利用实时荧光定量PCR技术检测脂滴形成相关基因的mRNA表达水平,并与乳脂率及脂肪酸含量进行相关性分析。试验结果显示,BTN1A1、XDH、PLIN1和PLIN2基因具有相同的表达趋势:H组>M组>L组;其中H组德宏奶水牛乳腺组织BTN1A1、XDH、PLIN1和PLIN2基因mRNA表达水平均极显著高于M组和L组(P<0.01);M组BTN1A1基因表达水平与L组差异不显著(P>0.05),但XDH、PLIN1和PLIN2基因mRNA表达水平均极显著高于L组(P<0.01)。相关性分析表明,BTN1A1、XDH、PLIN1和PLIN2基因表达水平均与乳脂率、总脂肪酸、长链脂肪酸及不饱和脂肪酸含量呈极显著正相关(P<0.01)。本研究结果表明,BTN1A1、XDH、PLIN1和PLIN2基因在乳腺组织的表达可能对德宏奶水牛的乳脂合成及分泌有显著促进作用,可为深入解析脂滴形成相关基因在泌乳过程中的调控机制提供参考。     

低容量喷雾技术的应用效益

对防治病虫害的喷雾技术进行了试验研究，结果表明：低容量喷雾较高容量喷雾天敌青蛙死亡率降低46.6％，对害虫防效提高，省药省工。在用药成本降低50％时防效仍达70．33％～90．88％。