不同发芽床对水稻种子发芽率的影响

用发芽纸和河砂(深褐色细砂)作为发芽床,对水稻种子进行发芽率检测.结果表明,不同的发芽床对发芽率结果影响很大.分析发现砂床可以明显减少不正常幼苗所占的比例.因此,在对水稻种子进行发芽检测时,对于纸床检测发芽率不合格且不正常幼苗多的情况下,应该用砂床进行重新检测,以得出种子的真实发芽率.     

曝气复合式生态浮床强化修复污水厂尾水的试验研究

采用曝气复合式生态浮床强度修复污水厂尾水,在水力停留时间为1.5d和水温为17.8～21.5℃的条件下,研究了曝气复合式生态浮床对COD、氨氮、总氮和总磷的去除效果。研究结果表明,曝气复合式生态浮床对COD、氨氮、总氮和总磷的平均去除率分别为33.9%～53.1%(平均值44.0%)、37.97%～64.45%(平均值50.8%)、33.46%～57.25%(平均值44.9%)和去除率5.43%～72.62%(平均值50.97%),其出水COD浓度远低于《城镇污水处理厂污染物排放标准》(GB18918-2002)的一级A标准。对比无/有曝气复合式生态浮床发现,曝气强化作用对复合式生态浮床修复效果的改善具有较重要的效果。曝气复合式生态浮床强化系统是一种运行管理方便、成本低廉、无需占有耕地。     

低温条件下组合式生态浮床系统净化微污染水体的特性研究

为研究低温对生态浮床水质净化效果的影响,引入陶粒作为浮床的基质,构筑了美人蕉-陶粒基质组合式生态浮床系统,研究在低温条件下其对微污染水体水质净化的效果特性。结果表明,在进水温度为0.5~15℃,进水DO浓度为4.94~6.65mg/L,水体交换时间为7d下,该生态浮床系统对水体中NH+4-N、NO-3-N、NO-2-N、TN、COD和色度的平均去除率为36.30%、77.37%、50.34%、52.56%、16.89%和70.99%。当水体的温度低于5.0℃,该生态浮床系统对水体中NH+4-N、NO-2-N、TN、COD和色度的去除效果均有所下降。     

渠床土壤二维稳定入渗率实验及渗漏损失计算

本文针对干旱地区、连续供水的大中型灌区渠道效率评估需要,用保角映射原理简化稳定入渗率的实验计算式;在克服渠床土壤空间变异性影响、改进国外的分离式静水套坑法为合一式静水套统、测定二维稳定入渗率实验法,求得一维流稳定入渗率的二维改正系数r;结合理论计算,可简便求得渠道渗漏损失用于输水效率评估。     

9 R-60型揉碎机试验台设计及单因素试验研究

9R-60型揉碎机目前应用非常普遍,但因其功耗大、效率低等实际问题急需对其结构参数进行优化设计。为此,在现有机型的基础上,设计并搭建了一个长、宽、高分别为718、712、687 mm的9R-60型揉碎机试验台。经过强度校核,设计了连接主轴等关键零件,在传动主轴和皮带轮之间通过联轴器、连接主轴和支架等接入JN 3 3 8-AN系列直连式扭矩转速传感器,为后续开展功率、揉碎质量等目标参数优化设计的单因素(如转子转速、秸秆喂入速度和喂入量等因素)正交试验和振动测试试验提供了平台。对揉碎机进行单因素试验表明:揉碎机揉碎质量随主轴转速的增大呈现增大的趋势,随喂入速度的增大呈现减小的趋势,随喂入量(不超过机器本身最大喂入量)的增大秸秆丝化率变化趋势几乎都在95%左右;揉碎机功耗随主轴转速、喂入量、喂入速度的增加呈现增大的趋势。     

稳定作业下道床动态行为的离散元模拟与试验研究

针对稳定作用下有砟道床的研究.采用具有真实几何形状的簇颗粒模拟道碎,建立简化缩小比1:8稳定作业下道床三维离散元模型,模拟分析不同激振频率作用下道床的宏细观动态行为.建立与轨枕模型同尺寸的试验模型,通过试验与仿真分析中轨枕的沉降量对比验证,确定试验以及构建的轨枕-道床模型的有效性与可靠性.进一步利用该试验分析道砟振动加...     

Experiences with Rice Grown on Permanent Raised Beds: Effect of Crop Establishment Techniques on Water Use,Productivity, Profitability and Soil Physical Properties

In recent years, conventional rice production technologies have been leading to deterioration of soil health and declining farm profitability due to high inputs of water and labor. Conservation agriculture(CA) based resource-conserving technologies i.e. zero-tillage(ZT), raised-bed planting and direct-seeded rice(DSR) have shown promise as alternatives to conventional production technologies to overcome these problems. Present study was undertaken during 2009–2012 to establish an understanding of how permanent raised bed cropping system could be practiced to save water at the field application level to improve water productivity and also have the capability to enhance productivity, profitability and soil physical quality. The results showed that among different crop establishment techniques, conventional-tilled puddle transplanted rice(CT-TPR) required 14%-25% more water than other techniques. Compared with the CT-TPR system, zero till direct-seeded rice(ZT-DSR) consumed 6%–10% less water with almost equal system productivity and demonstrated higher water productivity. Wide raised beds saved about 15%–24% water and grain yield decrease of about 8%. Direct-seeded rice after ZT or reduced tillage or on unpuddled soil provided more net income than CT-TPR. The CTTPR system had higher bulk density and penetration resistance due to compaction caused by the repeated wet tillage in rice. The steady-state infiltration rate and soil aggregation( 0.25 mm) were higher under permanent beds and ZT and lower in the CT-TPR system. Under CT-TPR, soil aggregation was static across seasons, whereas it improved under no-till and permanent beds. Similarly, mean weight diameter of aggregates was higher under ZT and permanent beds and increased over time. The study reveals that to sustain the rice productivity, CA-based planting techniques can be more viable options. However, the long-term effects of these alternative technologies need to be studied under varying agro-ecologies in western Uttar Pradesh, India.     

The Bioactive Potential of Trawl Discard: Case Study from a Crinoid Bed Off Blanes (North-Western Mediterranean)

Although knowledge of the bioactive compounds produced by species inhabiting coastal waters is increasing, little is known about the bioactive potential produced by marine species occupying deeper habitats with high biodiversity and productivity. Here, we investigate about the bioactive potential of molecules produced by species that inhabit the crinoid beds, a poorly known essential fish habitat affected by trawling, wherein large amounts of commercial and noncommercial species are discarded. Based on a trawl survey conducted in 2019, 14% of the 64 species discarded on crinoid beds produce molecules with some type of bioactive potential, including; soft corals (Alcyonium palmatum); tunicates (Ascidia mentula); bony fish, such as horse mackerel (Trachurus trachurus); European hake (Merluccius merluccius); and chondrichthyans, such as small-spotted catshark (Scyliorhinus canicula). In addition, 16% of the discarded species had congeneric species that produce compounds with bioactive potential, indicating that such species might also possess similar types of bioactive molecules. Molecules with antioxidant, antitumour, antihypertensive, and antibacterial properties were the most frequent, which could provide the basis for future research aiming to discover new marine-based drugs and compounds for other human uses. Among all species or genera that produce compounds with bioactive potential, 68% presented medium or high vulnerability to trawling. Results show that the discarded catch contains many species, which produce different bioactive compounds that represent an added-value resource. These results highlight the importance of manage properly crinoid beds, to ensure that species that produce molecules with bioactive potential inhabiting these habitats are protected.     

磷脂脂肪酸生物标记法分析养猪发酵床微生物群落结构的空间分布

采用磷脂脂肪酸(Phospholipid Fatty Acids,PLFA)生物标记法分析发酵床大栏养猪微生物群落结构的空间分布特点。从发酵床的5个区域(A、B、C、D、E)和3个层次(表层、中间层和底层)采集垫料样品,利用Sherlock MIS 4.5系统分析各样品的PLFA。结果表明,15:00、17:00、a15:0等7种PLFA在各样品中均有分布,为完全分布型,而a12:0和17:1 w6分别只在A区和B区分布,为不完全分布型。指示细菌、真菌、放线菌、革兰氏阳性细菌(G+)、革兰氏阴性细菌(G-)的PLFA及总PLFA在D区表层分布量最大。在各垫料中,PLFA分布量均表现为细菌真菌放线菌。A区各层次的真菌/细菌比值显著高于其他区域(P0.05),而G+/G-比值则显著低于其他区域(P0.05)。多样性分析表明,不同区域和层次的垫料Simpson指数、Shannon指数和Pielou指数值均呈现显著差异(P0.05)。聚类分析表明,当兰氏距离为117.1时,可将各样品聚为两个类群:类群Ⅰ包含A区的垫料,其特征是指示不同微生物的PLFA种类少和含量低;类群Ⅱ包含其他4个区域的垫料。当兰氏距离为23.4时,B区和D区各层次样本聚在同一亚类群中,其PLFA种类多、含量高,而C区和E区各层次样本聚在另一亚类群中,其PLFA含量中等。主成分分析表明,主成分1和主成分2基本能将发酵床不同空间垫料样本区分出来,其中A区单独归在一类群,D区和B区归在一类群,C区和E区归在一类群,与聚类分析结果一致。综上,发酵床大栏养猪不同空间的微生物种群结构不同,A区微生物种类少、含量低,而B区和D区微生物种类多、含量高。     

家禽发酵床养殖环境对病原微生物的防控作用研究

[目的]检测微生物发酵床养禽基质垫料中病原性大肠杆菌和沙门氏菌的数量,分析微生物发酵床技术对禽舍中病原菌的生物防控作用.[方法]参考国标检测环境中大肠杆菌和沙门氏菌的方法,以传统大棚养禽舍为对照,检测发酵床养鸡和发酵床养鸭舍中大肠杆菌和沙门氏菌的数量,同时检测动物肠道中2种病原微生物的数量指标,从环境微生物和动物体内携带微生物方面分析发酵床养禽技术对病原微生物的抑制作用.[结果]发酵床基质中2种病原微生物的数量明显低于普通饲养舍组,发酵床养殖环境中禽的肠道大肠杆菌和沙门氏菌的数量也低于普通养殖环境中动物体内携带的病原菌数量.[结论]发酵床养殖环境可以显著抑制病原微生物的繁殖,对控制禽类的细菌性传染病具有积极的生态安全意义.