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1.
In observation-cage experiments some new contact kairomones for the egg parasiteTrichogramma evanescens Westwood are demonstrated.T. evanescens females search significantly longer on cabbage leaves treated with the wing scales of two hosts,Pieris brassicae L. andP. rapae L. Further, egg washes ofP. brassicae containing an oviposition deterrent pheromone for the butterflies, were found to have a contact-kairomonal effect on the parasite.T. evanescens females search significantly longer on cabbage leaves sprayed with a methanol or water wash ofP. brassicae eggs than on leaves treated with the solvent only.Hymenoptera: Trichogrammatidae.Lepidoptera: Pieridae. 相似文献
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Fourteen volatile compounds occurring in leaf trichomes of yellow squash (Cucurbita pepo L. cv. Early Prolific Straightneck) were identified. These compounds accounted for 83.5% of the volatile matrix. Ubiquitous constituents of the epidermis (myristic, palmitic, and stearic acids,n-tricosane, andn-pentacosane) accounted for 73.7%; these compounds were not bioassayed. The volatileso-,m-, andp-xylene, toluene, 2-heptanone, (R)-(+)- and (S)-(–)-limonene, and germacrene D were tested for their influence on attraction and oviposition by the pickleworm moth (Diaphania nitidalis Stoll.). No single compound, except germacrene D, was attractive. (R)-(+)-Limonene and 2-heptanone were weakly repellent. Mixtures of the highly volatile fractions were as attractive as volatiles emanating from whole, intact leaves. Oviposition levels on treated artificial sites corresponded with levels of visitation. Oviposition was significantly stimulated by whole-leaf volatiles, and (S)-(–)-limonene caused a slight but significant reduction.Mention of a trade name or proprietary product does not constitute a warranty or guarantee by the U.S. Department of Agriculture, nor does it imply exclusion of other products that may also be suitable. 相似文献
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Jiaqi Zheng Shuang Sun Xu Hu Zhaohan Yu Yue Fu Dan Chen Dong Wang Weihao Cai Huamin Zhou Yunming Wang 《Advanced functional materials》2023,33(15):2213343
High-performance damping materials are significant toward reducing vibration and maintaining stability for industrial applications. Herein, a yolk–shell piezoelectric damping mechanism is reported, which can enhance mechanical energy dissipation and improve damping capability. With the addition of yolk–shell particles and carbon nanotube (CNT) conductive network, damping properties of various resin matrices are enhanced with the energy dissipation path of mechanical to electrical to heat energy. Particularly, the peak loss factor of epoxy composites reaches 1.91 and tan δ area increases by 25.72% at 20 °C. The results prove the general applicability of yolk–shell piezoelectric damping mechanism. Besides, the novel damping materials also exhibit excellent flexibility, stretchability, and resilience, offering a promising application toward damping coating, indicating broad scope of application in transportation and sophisticated electronics, etc. 相似文献
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Chemical mediation of egg capsule deposition by mud snails 总被引:1,自引:0,他引:1
Mud snails (Ilyanassa obsoleta = Nassarius obsoletus = Nassa obsoleta) deposit eggs in protective capsules on hard substrata in soft bottom environments. We studied sites of egg capsule deposition and snail movement responses to odors to determine if chemoreception plays a role in deposition site selection. From results of field surveys, laboratory experiments, and field experiments, we conclude that mud snails use chemoreception for capsule deposition. Attractive odors originate from mud snail and whelk egg capsules and from living bivalves. Evidence for attractive odors from conspecifics is equivocal. Capsules are deposited on living odor sources and nearby hard substrates. We hypothesize that deposition of capsules on living substrates increases the likelihood that embryos will survive by decreasing the chance of smothering of embryos by sediments. 相似文献
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开发海绵橡胶球(固)-水(液)两相清洗系统,用于豆浆污染的管式膜的清洗.通过海绵橡胶球清洗与传统大量水冲清洗方法对水通量恢复率和蛋清截留率的比较,确认了前者具有良好的清洗效果.前者恢复率比后者高约10%,蛋清截留率基本不受影响,对膜孔径无明显影响. 相似文献
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本文通过测定核桃油酸价、过氧化值、丙二醛含量、碘值和DPPH自由基清除率五个指标的变化研究比较蛋清蛋白膜、大豆分离蛋白膜及其与木糖美拉德反应产物膜包裹对核桃仁脂质过氧化的影响。结果表明,随着反应时间(08d)的增加,核桃仁酸价、过氧化值和丙二醛含量均呈现上升趋势,DPPH自由基清除率均呈现下降趋势,而碘值则变化不明显。加热第8d时,四种膜包裹核桃仁的酸价、过氧化值和丙二醛含量均小于未包膜的核桃仁,DPPH自由基清除率高于未包膜的核桃仁。四种膜包裹核桃仁的酸价无显著性差异(p>0.05);而过氧化值中以蛋清蛋白膜组较高,且其余三组的无显著性差异(p>0.05);四种膜包裹核桃仁的丙二醛含量均明显低于未包膜组,延缓丙二醛含量上升的效果依次为:大豆分离蛋白-木糖膜>蛋清蛋白-木糖膜>大豆分离蛋白膜>蛋清蛋白膜;大豆分离蛋白-木糖膜包裹核桃仁保留的DPPH自由基清除率明显高于其它三种膜。综上所述,两种蛋白及其美拉德反应产物膜包裹均可延缓核桃仁脂质过氧化,综合各项指标其效果依次为:大豆分离蛋白-木糖膜>蛋清蛋白-木糖膜>大豆分离蛋白膜>蛋清蛋白膜。 相似文献
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为快速检测污染鸡蛋的致病菌,实验从鸡蛋蛋体表面得到2株菌X1、X2,结合16S r RNA克隆及质粒测序分子方法对2株菌分类分析,发现2株菌X1和X2分别为:蜡样芽孢杆菌Bacillus cereus NC7401(AP007209)、金黄色葡萄球菌Staphylococcus aureus(AP003088)。针对两种菌的nhe、nuc基因具有较强的保守性,设计2套环介导等温扩增(LAMP)引物。先进行反应体系优化,得到25μL LAMP反应体系最适温度为60℃、最适Mg SO4添加量为1.5μL,引物最适量为2.0μL。再进行二重LAMP鉴定2株污染鸡蛋的致病菌,发现目的菌X1和X2的特异性扩增结果为阳性,其他9株非目的菌扩增结果为阴性,其灵敏度检测限达10 fg/μL。此二重LAMP检测法有快速、特异、灵敏的特点,可快速检测食源性致病菌。 相似文献