Y型网式过滤器堵塞过程对有机肥浓度的响应研究

为研究水肥一体化设备中用于过滤有机肥的Y型网式过滤器的堵塞规律,对Y型网式过滤器在初始流量500 L/h、水源压力117.6 k Pa下,设置25、30、40、50 g/L共4种黄腐酸钾有机肥肥液质量浓度,进行了过滤器堵塞试验,分析了Y型网式过滤器的局部水头损失与单个滤孔滤网清洁度(单个滤孔有效过水断面面积与孔隙总面积比值) S/S0的关系,并利用XRD分析了过滤器内堵塞物质的成分。结果表明:肥液质量浓度对过滤器滤网清洁度影响显著,建议肥液质量浓度不超过40 g/L;过滤器局部水头损失在S/S0减小到10%后才逐渐开始增大,过滤器局部水头损失与滤网清洁度、肥液质量浓度有关,利用多项式拟合给出了过滤器滤网清洁度与肥液质量浓度、施肥持续时间的关系式及局部水头损失与肥液质量浓度、滤网清洁度的关系式;滤网堵塞物质主要成分为硫酸钙、草酸钙。本研究结果可为水肥一体化设备中过滤器的选择提供理论参考。     

农药自动混药装置的研究现状与展望

目前,我国农作物病虫害防治主要依靠施用农药,现有的大多数农药剂型需要加水稀释,配制成一定浓度后再施用。近年,我国农业航空迅速发展,对农业航空的智能化农业机械装备的需求变得非常迫切。系统总结了农药自动混药装置类型以及农药自动混药装置特点,通过对农药自动混药装置研究发展概况分析,阐明了国内农药自动混药装置所存在的问题,展望未来农药混药装置的发展趋势,为后续的研究方向奠定基础。     

草坪草屑的加工与利用

我国每年修剪草坪产生大量的草坪草屑,对草坪草屑的加工利用,可以对我国能源、饲料、肥料及蛋白资源的短缺起到一定的缓解作用,因此如何对草坪草屑进行合理利用已成为一项重要的研究课题。本文综述了草坪草屑能源化、饲料化、肥料化和深加工4种利用方式,详细介绍了草坪草屑在发酵生产能源、饲喂家畜、堆肥还坪以及加工叶蛋白等方面的研究进展,指出禾本科草坪草屑和豆科草坪草屑应采用不同的处理方式,对各加工方式的投入和产出也应进行进一步的量化核算,同时总结并展望了草坪草屑利用方式的发展前景。     

Interactions of baseflow habitat constraints: Macroinvertebrate drift,stream temperature,and physical habitat for anadromous salmon in the Calapooia River,Oregon

1. The Calapooia River in western Oregon supports a small winter steelhead trout (Oncorhynchus mykiss) population and historically supported spring Chinook salmon (Oncorhynchus tshawytscha). Early timber harvesting removed the riparian forest, and log transportation practices simplified the channel. Those disturbance legacies continue to affect fish habitat by limiting shade and channel complexity, complicating conservation efforts.
2. To evaluate juvenile salmonid rearing potential, macroinvertebrate drift, thermal regime and physical habitat were measured at eight sites in 24 km of the upper river during late summer baseflow.
3. Overall physical habitat was simple, with few functioning instream structures or pools. During the 22‐day drift study, flows declined and maximum site stream temperatures ranged from 23.1°C at the lower end to 16.4°C 24 km upstream.
4. Macroinvertebrate drift concentrations ranged from 0.7–13.7 ind. m^?3 with biomasses from 0.02–1.23 mg m^?3. Drift concentration biomass was higher upstream (P  = 0.006) than downstream and declined overall (P  < 0.001) during the study. Drift biomass was dominated by five taxon groups – Baetis tricaudatus, Calineuria californica, Hesperoperla pacifica, Simulium spp., and Chironomidae, which were 65% of total biomass. During twilight, total biomass and biomass of B. tricaudatus, Simulium spp., and Chironomidae (both larvae and adults) were higher.
5. Total drift declined dramatically over the study period owing to decreases in drift concentration and a 58% decline in discharge, greatly reducing overall drift and available food resources for juvenile‐rearing salmonids.
6. The upper catchment, both with cooler temperatures and higher food availability, provided the best conditions for juvenile anadromous salmonids to survive late summer conditions. Conservation consequences of climate change‐induced alterations in flow and temperature may further affect habitat quality for juvenile salmonids in this catchment in the coming decades.

     

Chemical composition of Lippia spp. essential oil and antimicrobial activity against Aeromonas hydrophila

Phytotherapy can replace antibiotic administration as an alternative to control Aeromonas hydrophila, one of the main bacteria involved in the aetiology of farmed fish diseases. Given that plants of the Lippia spp. genus show biological potential for antimicrobial activity, this study evaluated the chemical composition of essential oils extracted from Lippia alba, Lippia origanoides and Lippia sidoides and their activity against A. hydrophila. The oils were obtained by steam distillation in a Clevenger‐type apparatus and their composition determined by gas chromatography and mass spectrometry (CG/MS). Antibacterial activity was assessed by calculating the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using broth microdilution method. The main compounds identified were geranial (25.4%) and neral (16.6%) in L. alba oil, carvacrol (40.4%) and p‐cymene (11.4%) in L. origanoides oil and thymol (76.6%) and ortho‐cymene (6.3%) in L. sidoides oil. The three Lippia species showed bacteriostatic and bactericidal action against A. hydrophila, with MICs and MBCs ranging from 1250 to 5000 μg mL^?1. Of the species tested, the best performance was obtained with essential oil of L. sidoides.     

圆口铜鱼精浆的理化性质分析

对圆口铜鱼(Coreius guichenoti)精浆离子和氨基酸成分及精液生理特性进行了检测分析。结果显示,圆口铜鱼精液pH值为7.3,呈弱碱性;精液浓度为39.7%,精子密度为5.3×10~9个/mL;精浆离子以Na~+含量88.7 mmol/L最高,其次是K~+,之后为Ca~(2+)、Mg~(2+)、Zn~(2+)、Cu~(2+);精浆水解氨基酸总量为2 872.69μmol/100mL,其中以脯氨酸含量最高,蛋氨酸、酪氨酸和组氨酸含量最低。该结果填补了圆口铜鱼繁殖生物学的相关数据,为圆口铜鱼规模化人工繁育提供了基础资料。     

Effect of Salt Concentration and Extremely Halophilic Archaea on the Safety and Quality Characteristics of Traditional Salted Anchovies

Extremely halophilic archaea (EHA) might play an important role in salted fish production. So far, limited information has been available on the effect of EHA and salt concentration on the safety and quality characteristics of salted anchovies. Eight Halobacterium salinarum strains were isolated from different sea salt samples and subjected to phenotypic and genotypic characterization. The strains were then inoculated into fresh salt before addition to anchovies. A total of 18 experimental productions were performed. The inoculated trials showed the lowest counts of undesired microorganisms. In particular, salted anchovies produced with Hbt. salinarum H11 showed the lowest histamine concentration as well as the highest sensory scores. Differences in terms of volatile organic compounds (VOCs) were estimated among trials. Furthermore, multivariate analysis showed that experimental production performed with a reduced amount of salt (175 g of sea salt per kg of anchovies) did not affect the final quality of salted anchovies. The strain Hbt. salinarum H11 produced salted anchovies with well-appreciated organoleptic features. Thus, the addition of EHA and the use of a lower amount of sea salt might represent a valuable alternative to the traditional method for production of salted anchovies.     

12种杀虫剂对日本通草蛉不同虫态的毒力及安全性评价

为明确常见杀虫剂对日本通草蛉各虫态的影响,在室内分别采用浸渍法和喷雾法测定了12种(8类)杀虫剂对日本通草蛉卵、幼虫、蛹和成虫的毒性,并评价了杀虫剂对日本通草蛉的毒性风险。结果表明,高效氯氰菊酯对日本通草蛉为极高风险,毒死蜱、吡虫啉、烯啶虫胺和阿维菌素为高风险,溴氰虫酰胺、啶虫脒和氯虫苯甲酰胺为中等风险,噻嗪酮、吡蚜酮、螺虫乙酯和甲氧虫酰肼为低风险;与其他虫态相比,12种杀虫剂对日本通草蛉蛹的毒性均为最低。在害虫生物防治及综合治理中应尽量选用对日本通草蛉毒性低的杀虫剂,以起到保护天敌的作用。     

不同类型水稻品种产量和氮素吸收利用对大气CO2浓度升高响应的差异

目的 探明不同类型水稻品种产量和氮素吸收利用对FACE(大气CO₂浓度增高)响应的差异。方法 以常规粳稻、杂交籼稻、常规籼稻共6个品种为供试材料,研究FACE对不同类型水稻产量、氮素吸收利用的影响。结果 1）FACE处理极显著提高了水稻产量,平均增加24.17%, 常规籼稻增幅最大,FACE和对照均以杂交籼稻最高;2）FACE处理显著增加了单位面积穗数,常规粳稻增幅最大,并显著增加了杂交籼稻和常规籼稻每穗粒数;3）FACE处理显著提高了成熟期吸氮量和氮素籽粒生产效率,成熟期吸氮量平均增加21.23%,杂交籼稻增幅最大, FACE和对照均以常规籼稻最高;氮素籽粒生产效率平均增加7.33%,杂交籼稻增幅最大,FACE和对照均以杂交籼稻最高。成熟期吸氮量对产量促进作用略大于成熟期氮素籽粒生产效率;4）FACE处理降低了植株含氮率,成熟期平均下降0.105个百分点,常规粳稻降幅最大。FACE处理极显著提高植株干物质量,成熟期平均增加23.95%,常规籼稻增幅最大;FACE处理显著提高常规籼稻和杂交籼稻成熟期单穗吸氮量,分别增加10.79%、13.93%,但常规粳稻下降了9.60%;FACE处理显著提高了成熟期群体吸氮强度,平均增加22.29%,杂交籼稻增幅最大。FACE处理对水稻全生育期天数无显著影响;FACE处理显著提高茎鞘、叶片、穗各器官吸氮量,叶片增幅最大,平均增加51.86%,杂交籼稻增幅最大;FACE处理显著提高了不同生育阶段吸氮量,抽穗-成熟阶段增幅最大,平均增加108.90%,杂交籼稻增幅最大;5）植株干物质量、单穗吸氮量、吸氮强度、穗吸氮量、抽穗-成熟阶段吸氮量对成熟期总吸氮量的促进作用分别大于植株含氮率、单位面积穗数、生育天数、茎鞘叶吸氮量、移栽-分蘖和分蘖-抽穗阶段吸氮量;6）FACE处理显著提高了氮肥偏生产力,降低了每百千克籽粒需氮量,前者平均增加24.16%,常规籼稻增加最多;后者平均降低4.7%,常规籼稻降幅最大。结论 FACE处理可显著提高水稻产量和氮素吸收利用效率,但品种间差异较大。     

粉碎机异形筛片气流场数值模拟及试验研究

针对传统环筛式锤片饲料粉碎机存在气固环流层影响粉碎机性能的问题,采用理论分析、数值模拟、粉碎性能试验相结合的方法,对粉碎机安装异形筛片时粉碎室内物料颗粒受到的气力作用和内部流场运动规律进行研究。分析粉碎机使用异形筛片对粉碎性能的影响。优化后的异形筛片分别命名为B_1(小圆弧半径R_1=51mm)、B_2(R_1=83mm)、B_3(R_1=93mm),利用流体动力学软件对粉碎室安装3种异形筛片的气流场进行数值模拟,获得粉碎室气流场分布信息。在相同工况下,对装有3种异形筛片的CPS-420型粉碎机进行粉碎性能试验,分析不同筛片对物料粉碎效果的影响。模拟结果表明:粉碎机采用间隔分段圆弧筛片后,粉碎室环流区域产生不同强度的涡旋,能够改变物料环流运动规律,提高物料过筛能力;锤片组扫过区域的气流呈现出较为杂乱无序的分布状态,有利于形成湍流运动,从而增加物料颗粒受打击几率。粉碎性能试验结果表明:锤片饲料粉碎机安装B_3筛片的粉碎机生产效率,较B2、B1筛片分别提高8.1%、16.0%,吨料耗电量分别降低10.5%、15.0%,温升分别降低0.6和0.1℃。优化后的3种异形筛片,能够提高粉碎机的生产效率,降低电能的损耗、改善物料温升,对提高锤片饲料粉碎机性能具有积极意义。