Acoustic emission on failure analysis of rubber-modified epoxy resin

Rubber-modified epoxy resins have been employed as adhesive and matrix materials for glass and corbon-fiber composites. The behavior of fracture around a crack tip for rubber-modified epoxy resin is investigated through the acoustic emission (AE) analysis of compact tension specimens. Damage zone and rubber particles distributed around a crack tip were observed by a polarized optical microscope and an atomic force microscope (AFM). The damage zone in front of pre-crack tip in rubber-modified specimen (15 wt% rubber) began to form at about 13 % level of the fracture load and grew in size until 57 % load level. After that, the crack propagated in a stick-slip manner. Based on time-frequency analysis of AE signals and microscopic observation of damage zone, it was thought that AE signals with frequency bands of 0.15–0.20 MHz and 0.20–0.30 MHz were generated from cavitation in the damage zone and crack propagation, respectively.     

离子注入水稻诱发当代损伤效应的研究

籼型转基因水稻种子为材料 ,用不同的离子种类、能量和剂量进行辐照 ,采用 3因子 3水平 9个处理的正交试验 ,调查离子束注入对诱变当代幼苗存活率及幼苗生长速度起主导作用的物理因子 ,以研究离子注入水稻诱发当代损伤的效应。结果发现 ,影响存活率效应最大的是注入离子的能量 ,以低能量 (15kev)的离子注入效果最佳 ;影响苗期生长的主效因子是注入离子的种类 ,以Ar+ 为最佳     

Path analysis: a novel approach to determine the contribution of nematode damage to East African Highland banana (Musa spp., AAA) yield loss under two crop management practices in Uganda

Damage caused by plant-parasitic nematodes on East Africa Highland banana cultivar Mbwazirume was evaluated at Sendusu, Central Uganda. Banana plots were either nematode-infested or non-infested and received either continuous heavy mulch or were finger millet (Eleusine coracana) inter-cropped. An infestation with banana weevil, Cosmopolites sordidus, occurred naturally. Suckers detached from third crop cycle harvested plants were indexed for root and corm damage. Nematodes were extracted from the indexed roots. Banana weevil damage was observed in a cross-section through the corm of the harvested plant. Relationships between root damage, corm damage and nematode population densities were examined using correlation analyses. Path analysis was used to establish their relative effects on bunch weight. Independent of the type of crop management, percentage root necrosis, percentage dead roots, Radopholus similis and Helicotylenchus multicinctus population densities were each negatively correlated with bunch weight. Banana weevil damage and Pratylenchus goodeyi population densities were not correlated with bunch weight (P≤0.05). Path analysis revealed that root necrosis under heavy mulching and dead roots under finger millet inter-crop were the major factors associated with reduced bunch weight. Independent of the type of crop management, path analysis demonstrated that R. similis and then H. multicinctus contributed most, and to a lesser extent P. goodeyi, to root necrosis and dead roots. C. sordidus damage to the inner or outer corm appeared not to affect bunch weight.     

海南冬季主要瓜菜寒害风险区划

基于自然灾害风险分析原理,利用海南岛18个市县历年逐日气象要素、瓜菜产量、面积、寒害灾情和DEM等资料,构建基于瓜菜生物学特性的寒害致灾等级指标,综合寒害致灾危险性、孕灾敏感性、承灾体易损性和防灾能力,评估海南岛冬季瓜菜寒害风险。结果表明:西瓜冬季寒害危险性从中部向东西减小,豇豆和丝瓜冬季寒害危险性从南向北加重,辣椒冬季寒害危险性从东南向西北增加,瓜菜不同等级寒害风险概率分布形式差异明显;瓜菜冬季寒害孕灾环境敏感性从中部五指山地区向周围低海拔区降低;瓜菜冬季寒害灾损风险和防灾能力在区域上存在明显差异。瓜菜冬季寒害综合风险分布形式总体一致,中部和北部高、南部和东西部沿海低。这种寒害风险分布主要受海南冷空气活动和地形因素作用,与实际寒害发生规律一致。     

诱发枇杷霜冻害的冰核细菌拮抗菌分离与筛选

[目的]筛选出具有防除枇杷INA细菌的拮抗菌.[方法]从枇杷根际土壤中分离冰核细菌拮抗菌,对其进行抑菌圈、杀菌能力、破坏冰核活性蛋白能力测定.[结果]从不同海拔地区的根际土壤中共分离得到128个菌株,其中有拮抗效果的有55株,平皿拮抗效果强的有15株,再经拮抗系数比较得到9株强拮抗菌菌株,最后筛选出l株杀菌率达98％、破坏冰核蛋白能力达100％的拮抗菌BL-36.[结论] BL-36既有杀菌效果又有破坏冰核蛋白能力,是具有较好利用前景的防除诱发枇杷霜冻害冰核细菌、减轻枇杷霜冻害的生物防治材料.     

洞庭湖区外来有害植物种类、分布及危害的研究

通过对洞庭湖区外来有害植物的调查,基本弄清了该地区现有外来有害植物37种,隶属15科,并对该地区外来有害植物的分布规律及危害特点进行了分析,危害严重的有水花生、加拿大一枝黄花、水葫芦、豚草、一年蓬、三叶鬼针草、斑地锦、牛筋草等,这为综合防除与利用外来有害植物提供了重要资料。     

主要热带果树煤烟病的为害性及病原菌种类研究

在海南等地的调查、测定结果表明,煤烟病对热带果树有一定为害性。在特别重病的情况下,芒果产量损失９．８％;芒果品种间对煤烟病抗病性有明显的差异。经鉴定,芒果、荔枝、柑桔、人心果、油梨、番石榴的煤烟病有８种;其中Ｍｏｌｉｏｌａ ｓｐｐ。,Ｔｒｉｐｏｓｐｅｒｍｕｍ ｓｐｐ．,Ｃａｐｎｏｄｉｕｍ ｓｐｐ．为优势种群。     

棉田玉米螟的发生为害及分布型研究

在河南棉区,第１代玉米螟在棉田为害严重,第２、３代很少为害棉花。不同类型田相比麦棉套种田受害较重。采用频次比较,聚集度指标判别等方法对棉田玉米螟的空间分布型进行了探讨。结果表明,麦棉套田螟卵块呈均分布,其余田块玉米螟卵、幼虫均属聚集分布。     

都兰县天然草地有毒植物调查

简述了都兰县天然草地有毒植物种类、毒性原理及毒草分布,提出防治毒草的对策,为今后进一步开展毒草防治和研究工作提供参考。     

棉蚜的鉴别与防治探讨

介绍了棉花虫害棉蚜不同虫态的形态特征及为害特征,并与相似虫害棉长管蚜、苜蓿蚜、菜豆根蚜、拐枣蚜等进行比较。同时总结了其发生规律和生活习性。然后从农业防治、物理防治、生物防治、化学防治等方面总结了该虫害的防治方法,并着重介绍了化学防治的用药时期及用药量。