乙基纤维素-艾叶粉溶液微胶囊的制备及缓释性能研究

文章首次以乙摹纤维素为壁材,采用溶剂蒸发法制得艾叶粉水溶液微胶囊.正交实验得出制备微胶囊的最佳工艺条件为:乙基纤维索:芯材:乙酸乙酯:水相=1:2.5:13:130(质量比),搅拌速度:1500 r/min,乳化时间:15 mim,水油两相混合搅拌时间:10 min.通过扫描电镜表征结果显示,所得微胶囊固体颗粒呈球形,分散性好,粒径在20～200 μm范围内.实验制得微胶囊最大载药量为48.07%,具有良好的包覆效果.透析缓释实验表明,微胶囊在37.0℃恒温生理盐水浸泡60 h后,仍有艾叶药理活性成分存在,较好地延长了储藏时间和药物有效作用时限.     

Induction of Plant Synomones by Oviposition of a Phytophagous Insect

Earlier investigations of host habitat location in the egg parasitoid Oomyzus gallerucae have shown that oviposition of the elm leaf beetle (Xanthogaleruca luteola) induces the field elm (Ulmus minor) to emit volatiles that attract the egg parasitoid. In this study we investigated the mechanism of this induction by testing the effects of differently treated elm leaves on O. gallerucae in a four-arm olfactometer. First we investigated which sequence of the herbivore oviposition behavior is necessary for the synomone induction. The following major sequences were observed: (1) Prior oviposition, the gravid female gnawed shallow grooves into the leaf surface. (2) After gnawing upon the leaf surface, the female attached about 20–30 eggs with oviduct secretion in the grooves. We experimentally mimicked the shallow grooves on the leaf surface by scratching the leaf surface with a scalpel (= scratched leaves). Volatiles from such scratched leaves did not attract the egg parasitoid. However, as soon as eggs with oviduct secretion, or only oviduct secretion, was applied to these scratched leaves, they emitted attractive volatiles. Application of oviduct secretion and eggs on undamaged leaves did not elicit release of attractive synomones. Thus, an elicitor is located in the oviduct secretion, but becomes active only when the leaf surface is damaged. Jasmonic acid is known as a mediator of plant responses induced by feeding of herbivorous arthropods, and we demonstrate that it mediates production of elm synomones that attract O. gallerucae. The plant's reaction to oviposition was systemic, and leaves without eggs near leaves with eggs emitted attractants.     

Aphid and Plant Volatiles Induce Oviposition in an Aphidophagous Hoverfly

Episyrphus balteatus DeGeer (Diptera, Syrphidae) is an abundant and efficient aphid-specific predator. We tested the electroantennographic (EAG) response of this syrphid fly to the common aphid alarm pheromone, (E)-β-farnesene (EβF), and to several plant volatiles, including terpenoids (mono- and sesquiterpenes) and green leaf volatiles (C6 and C9 alcohols and aldehydes). Monoterpenes evoked significant EAG responses, whereas sesquiterpenes were inactive, except for the aphid alarm pheromone (EβF). The most pronounced antennal responses were elicited by six and nine carbon green leaf alcohols and aldehydes [i.e., (Z)-3-hexenol, (E)-2-hexenol, (E)-2-hexenal, and hexanal]. To investigate the behavioral activity of some of these EAG-active compounds, E. balteatus females were exposed to R-(+)-limonene (monoterpene), (Z)-3-hexenol (green leaf alcohol), and EβF (sesquiterpene, common aphid alarm pheromone). A single E. balteatus gravid female was exposed for 10 min to an aphid-free Vicia faba plant that was co-located with a semiochemical dispenser. Without additional semiochemical, hoverfly females were not attracted to this plant, and no oviposition was observed. The monoterpene R-(+)-limonene did not affect the females’ foraging behavior, whereas (Z)-3-hexenol and EβF increased the time of flight and acceptance of the host plant. Moreover, these two chemicals induced oviposition on aphid-free plants, suggesting that selection of the oviposition site by predatory hoverflies relies on the perception of a volatile blend composed of prey pheromone and typical plant green leaf volatiles.     

壳聚糖对银杏叶水提液的絮凝工艺研究

采用天然高分子絮凝剂壳聚糖对银杏叶水提液进行絮凝提取,其目的是优化生产工艺,提高药液的澄清度和药液质量。实验利用光的吸收和散射定律,以絮凝率和总黄酮损失率为衡量指标,判断不同影响因素对絮凝效果的影响,并将其与醇沉工艺的提取方法进行比较。结果通过单因素实验先判断出有利于絮凝的趋势,之后又利用正交实验确定了絮凝的最佳工艺条件:絮凝剂质量浓度1.071 g/L,絮凝温度40℃,体系pH值4.9。并且得出壳聚糖对银杏叶水提液的絮凝工艺效果明显优于醇沉法。     

Major Sex Pheromone Components of the Australian Gum Leaf Skeletonizer Uraba lugens: (10E,12Z)-Hexadecadien-1-yl Acetate and (10E,12Z)-Hexadecadien-1-ol

Two sex pheromone components of the gum leaf skeletonizer, Uraba lugens (Lepidoptera: Nolidae), recently established in New Zealand, were identified. Gas chromatography (GC) electroantennographic detection analyses of female pheromone gland extracts gave three compounds that consistently elicited antennal responses. Chemical analyses, using GC and GC-mass spectrometry, in conjunction with 4-methyl-1,2,4-triazoline-3,5-dione and dimethyldisulfide derivatizations, identified these compounds as (10E,12Z)-hexadecadien-1-yl acetate (E10,Z12-16:Ac), (10E,12Z)-hexadecadien-1-ol (E10,Z12-16:OH), and (Z)-11-hexadecen-1-yl acetate (Z11-16:Ac). A trapping trial in Queensland, Australia, in 2002, indicated that a blend of the two major components E10,Z12-16:Ac and E10,Z12-16:OH could attract gum leaf skeletonizer males. In the same trial, E10,Z12-16:Ac alone trapped large numbers of an unidentified nolid, Nola spp. Further trials in Auckland, New Zealand established that these two components were sufficient and necessary for trap catch of males; adding minor gland components, (10E,12E)-hexadecadien-1-yl acetate (E10,E12-16:Ac), Z11-16:Ac, or octadecan-1-ol (18:OH), to the two-component lure did not result in increased trap catches. Behavioral observations and gland analyses of the Auckland population revealed that female moths begin calling soon after emergence, with peak calling and pheromone production occurring 7 hr into the scotophase. Analysis of gland extract at two-hourly intervals during the first activity period showed that the ratio of E10,Z12-16:Ac to E10,Z12-16:OH (mean of 86: 14, respectively) and pheromone titer were fairly constant. No qualitative or quantitative differences in pheromone components were detected between gland extracts from Tasmanian univoltine and Auckland bivoltine populations of U. lugens.     

等截面叶片钢板弹簧的有限元分析

钢板弹簧在装配和承载时,叶片之间存在摩擦力,采用传统的基于材料力学的计算公式无法考虑片间摩擦力的影响。本文应用有限元方法,考虑钢板弹簧装配和承载时各叶片之间的非线性摩擦力以及几何非线性,对某等截面叶片钢板弹簧的刚度及应力进行了计算并对结果进行了分析。     

悬浮液技术-火焰原子吸收光谱法测定银杏叶中钙铁锌

将银杏叶样品粉碎、过筛并悬浮在1.5g/L琼脂溶液中制成悬浮液,以火焰原子吸收光谱法成功地测定了银杏叶中钙、铁、锌。用L a 3+作为钙的释放剂以消除化学干扰。试验表明,加入适量盐酸可显著提高被测元素的吸光度。对盐酸溶液(1+1)用量、试液与空白溶液粘度的一致性、背景吸收干扰、检出限及特征浓度进行了考察。测定结果的相对标准偏差小于1.8%,测定结果与灰化法一致,相对误差小于±0.9%。可见,在火焰原子吸收光谱法中,以悬浮液法取代灰化法处理银杏叶样品是可行的。方法简便准确。     

滚动轴承保持架缺陷的图像处理及模式识别方法研究

轻系列滚动轴承保持架由于兜孔直径小、两半保持架之间钉孔距离相对较大等因素导致在铆压过程中易出现变形,造成铆压歪斜缺陷。为此,本文提出了基于图像纹理特征的模式识别方法用于保持架歪斜缺陷的准确识别。首先,改进了轴承图像归一化展开算法,实现了轴承图像展开起点的自动优化选择以避免误分割保持架、铆钉和滚动体;其次,设计了轴承图像保持架区域定位分割算法,准确分离出7个保持架区域;最后,分别提取保持架区域的Hu矩和旋转不变均匀局部二值模式(LBPrPiu,2R)作为纹理特征,并结合PCA降维方法构建轴承保持架缺陷识别的SVM分类模型。结果表明,基于Hu矩和LBPrPiu2,R的SVM模型的正确识别率分别为85%和100%。因此,轴承LBPrPiu2,R特征结合SVM模型对轴承保持架歪斜缺陷具有较好的识别效果。该方法有望为滚动球轴承保持架铆压工艺缺陷的自动识别提供参考。     

新型贝氏体板簧钢的组织及性能

针对汽车减重和环保问题,自行设计研制了车用新型贝氏体板簧钢,并对其组织和力学性能进行研究。结果表明,该钢经正火热处理即可得到无碳贝氏体组织;XRD检测表明,其物相组成以α相为主;该钢具有优良的综合力学性能和耐腐蚀性能,屈服强度近1200 MPa,抗拉强度达1400 MPa,常温下,冲击吸收能量达到73.2 J以上,强韧性配比优异。     

HuR and TIA1/TIAL1 Are Involved in Regulation of Alternative Splicing of SIRT1 Pre-mRNA

SIRT1 is a pleiotropic protein that plays critical and multifunctional roles in metabolism, senescence, longevity, stress-responses, and cancer, and has become an important therapeutic target across a range of diseases. Recent research demonstrated that SIRT1 pre-mRNA undergoes alternative splicing to produce different isoforms, such as SIRT1 full-length and SIRT1-ΔExon8 variants. Previous studies revealed these SIRT1 mRNA splice variants convey different characteristics and functions to the protein, which may in turn explain the multifunctional roles of SIRT1. However, the mechanisms underlying the regulation of SIRT1 alternative splicing remain to be elucidated. Our objective is to search for new pathways that regulate of SIRT1 alternative splicing. Here we describe experiments showing that HuR and TIA1/TIAL1, two kinds of RNA-binding proteins, were involved in the regulation of alternative splicing of SIRT1 pre-mRNA under normal and stress circumstances: HuR increased SIRT1-ΔExon8 by promoting SIRT1 exon 8 exclusion, whereas TIA1/TIAL1 inhibition of the exon 8 exclusion led to a decrease in SIRT1-ΔExon8 mRNA levels. This study provides novel insight into how the alternative splicing of SIRT1 pre-mRNA is regulated, which has fundamental implications for understanding the critical and multifunctional roles of SIRT1.