辐照技术在储粮害虫防治中的应用

辐照杀虫是利用电离辐射与害虫的相互作用所产生的物理、化学和生物效应,导致害虫不育或死亡的一种物理防虫技术.用于辐照杀虫处理的射线主要是γ射线(60Co或137Cs)、10 MeV以下电子束以及5 MeV以下的X射线,其中钴源辐照杀虫产业化发展迅速,电子束和X射线辐照发展相对滞后,随着近年来加速器技术的进步,电子束辐照杀虫显示出独特的优势,并受到越来越广泛的重视.辐照对不同储粮害虫、同一种储粮害虫的不同发育时期和性别有着不同的生物学效应,总体来看储粮害虫对辐照较为敏感:不同害虫的辐射敏感性顺序为:鞘翅目＞蜱螨目＞鳞翅目;同种害虫不同虫态的敏感性顺序为:卵、幼虫＞蛹＞成虫;雌性害虫的敏感性大于雄性害虫.粮食辐照杀虫工艺流程一般包括:辐照前处理、虫情调查、剂量决策、辐照处理、辐照后管理和重复辐照等几个部分.在辐照杀虫的工艺剂量(0.3～0.5 kGy)条件下,辐照对粮食的食用品质和功能特性没有影响,辐照后的粮食也不存在卫生安全性问题.因此,辐照杀虫技术作为一种安全有效的储粮害虫防治手段,是储粮化学药剂的一种重要补充和替代,在储粮害虫防治领域有着巨大的市场前景.     

The Staged Simulation Method for Power Electronics Circuits

This paper in troduces a staged simulation method fur power electronics circuits,presents an exampleued the method for the CSI/IM drive system.     

Electronegativity Scale of Elements Calculated by Density Functional Theory and Related Methods

In chemistry and many related fields, electronegativity (EN) is an important fundamental concept and its scale is a useful physcochemical parameter. Here, calculations of both ionization potentials and electron affinities are extended toward 107 elements and done by density functional theory at the local density approximation(LDA) level and the LDB level, i.e., the local density approximation level with further non-local corrections for exchange and correlation included self-consistently as well as the modified Slater transition-state method. The definite-differentiation method is employed into calculations of the electronegativity scale and the related parameters of 107 elements with very good results due to the consideration of relativistic effects. The calculation presented is to examine both the LDA and LDB approximations in calculations for the ionization potential and electron affinity of the elements with an improved or modified Slater transition-state method, and relativistic effects have also been taken into account for 107 elements compared with 103, 86 or less in the previous report under a spin polarized density function theory with some approximations to the exchange-correlation function. The calculation results for the various quantities represent an obviously improvement over some previous calculations. It is shown that the results calculated by the extended technique and the improved Slater transition-state method in general agree well with experimental values presented by Pearson, and are better than the reported values in many previous literatures. The developed new electronegativity scale will widely be applicable in many fields such as molecular structural parameterization expression, chemobiological activity optimization prediction, structure-activity quantitation modeling, functional chemical adaptization designing, and so on.     

The association of culm anatomy with lodging susceptibility in modern spring wheat genotypes

Selection for lodging resistant cultivars in cereal breeding programs is difficult due to the challenge of screening for this trait under natural field conditions. The identification of easily measurable culm traits related to lodging resistance would simplify the selection process. The present study was conducted to determine if differences in culm anatomy exist among modern wheat genotypes differing in lodging susceptibility, and to determine the association between culm characters and lodging. From a 2-year field study conducted in Edmonton, Alberta, 13 spring wheat cultivars were chosen based on predetermined susceptibility to artificially induced lodging. Morphological and anatomical culm measurements were made visually and with an environmental scanning electron microscope. Genotypes differed (P < 0.05) for plant height, number of internodes per culm, basal internode length and diameter, culm wall thickness and the number of vascular bundles, but not for adventitious root frequency, lumen diameter or sclerenchyma ring thickness. Mean genotype field scores for artificially induced lodging were correlated (P < 0.05) with plant height (r= 0.51) and the length of the fourth basal internode (r= 0.51). Short, wide basal internodes and thick culm walls were characteristic of three lodging tolerant genotypes: Kohika, Sapphire and Olso. Nevertheless, despite such apparent genotype specific association between culm anatomy and field lodging, general applicable associations were not observed for most traits. The most practical and easily selectable trait for lodging resistance within a wheat breeding program remains plant height. This revised version was published online in July 2006 with corrections to the Cover Date.     

不同前处理条件对动态光散射检测酪蛋白胶束粒径的影响

为了准确评价乳的稳定性和加工性能,探讨不同前处理条件对动态光散射检测酪蛋白胶束粒径的影响,研究了稀释液的种类(超纯水、钙咪唑缓冲液、模拟牛乳超滤液和牛乳超滤液)、稀释液温(4和25℃)和稀释液的放置时间(0~48 h)对脱脂乳中酪蛋白胶束粒径的动态光散射测试结果的影响,并将酪蛋白胶束粒径的动态光散射测试结果与冷冻透射电镜图像中测得的真实结果进行比较。研究发现以超纯水和钙咪唑缓冲液作为脱脂乳稀释液时,部分胶束发生解离,影响测试结果;采用牛乳超滤液及模拟牛乳超滤液作为稀释液时,胶束的微环境没有改变,反映了胶束的真实粒径及分布;放置24 h后,牛乳超滤液及模拟牛乳超滤液将产生颗粒;温度对测试有显著的影响(P0.05):4℃的样品用25℃的稀释液进行稀释后,动态光散射的计数率和粒径分别增大了16.6%和11.4%;25℃的样品用4℃的稀释液进行稀释后,计数率和粒径分别降低了16.1%和9.8%。结果表明酪蛋白胶束粒径的测试前处理较适宜的条件为:在与样品的温度相同条件下,以配置好后24 h内的模拟牛乳超滤液或牛乳超滤液(10 k Da超滤膜)作为脱脂乳的稀释液进行稀释。通过与冷冻电镜条件下测得的酪蛋白胶束粒径的真值比较,发现该前处理条件下酪蛋白胶束粒径的动态光散射测试结果的相对误差为-5.7%~1.8%,表明该样品前处理方法可用于动态光散射方法快速检测酪蛋白胶束粒径。研究结果为快速、准确地获取酪蛋白胶束的粒径信息,进而准确分析乳的稳定性及加工性能提供参考。     

In-field calibration of a dielectric soil moisture meter designed for use in an access tube

Abstract. The in-field calibration of a dielectric probe to measure soil water content is described. The probe uses an access tube analogous to that of the neutron probe. The dielectric constant was measured at soil depths of 10, 20, 30, 40, 60 and 100 cm. Cores of soil were then taken from the face of pits dug 30 cm from the access tube and their soil water contents determined by oven drying. The dielectric constant values measured by the probe were calibrated against water contents from these cores. We found that sensor depth needed to be included to achieve a good calibration model that explained 72% of the variance. It is argued that depth needs to be included because of artefacts introduced during the installation of the access tube.     

芒果不同品种果实的显微结构与品质的关系初探

采用紫花芒、桂香芒、红象牙和印度1号芒果的果实,通过扫描电子显微镜观察,发现果实皮孔少,开口小,蜡质密度大的紫花芒果实耐贮藏。分泌腔多的桂香芒和印度1号果实芳香味浓。果肉薄壁细胞中淀粉粒增多,果实愈趋近成热。薄壁细胞中淀粉粒多的桂香芒,果实后熟后含糖量高。     

Leaf litter decomposition in a chaparral ecosystem, Southern California

Decomposition losses from leaves of three evergreen chaparral species, scrub oak (Quercus dumosa), ceanothus (Ceanothus crassifolius), and manzanita (Arctostaphylos glauca), were quantified over a 2-y field exposure using litterbags. Changes in ash-free dry mass, C, and N were monitored at 2- to 6-month intervals at four replicate sites composed of patches of these three chaparral species. Three proximate C fractions were extracted from fresh and decomposing litter samples: polar and non-polar extractives (EXT), acid-solubles (ACID), and acid-insolubles (KLIG). The chemical structure of fresh and decomposed litter was additionally characterized using high-resolution solid-state ¹³C NMR spectroscopy, while morphological properties were examined by scanning electron microscopy (SEM). After 2 y, the litters had lost between 20.7%±1.2 (Ceanothus) and 35.2%±6.8 (Quercus) of their original ash-free dry mass. The manzanita decomposed at a significantly faster rate than the other two litter types during the first few months of field exposure. Yet, after 2 y, mass loss was greater for the oak. Differences in decomposition rates could not be accounted for based on a single litter quality index. Fresh manzanita exhibited a significantly higher N content, which could explain its initially faster decay rate. Fresh oak litter, on the other hand, had a relatively high ACID and O-alkyl C (O-ALK) content, which may have been responsible for its decay pattern. Fresh ceanothus contained a relatively low KLIG content, yet it decomposed more slowly than the two other species. The solid-state ¹³C NMR spectra of the ceanothus litter had two peaks characteristic of proanthocyanidins, which likely contributed to the recalcitrance of this litter type. SEM revealed that ceanothus leaf surfaces were left nearly unchanged after field exposure. In comparison, the oak and manzanita leaf surfaces were pitted and covered by microbial growth to the point of being unrecognizable. Taken together, our results indicate that a combination of biological, physical and chemical factors need to be examined to clarify the different decomposition rates and patterns of these three chaparral species.     

电子流注入水稻幼穗组织培养效应的研究

以两用核不育系新光S幼穗为材料,以γ射线辐照作对照,研究了电子流注入对水稻离体培养的反应。结果表明,电子流注入对离体培养的效应与γ射线辐照具有相似性。对愈伤组织的诱导、分化主要表现为抑制效应,但对植株再生具有促进作用。10～15秒电子流注入可使幼穗的出愈率和分化率保持对照水平或略低,而再生能力大幅度提高。     

抗福美双假单胞菌株的NTG化学诱变及分子探针鉴定

利用微生物的抗药性筛选抗福美双的假单胞菌株Ｔ４６，然后通过亚硝基胍（ＮＴＧ）化学诱变获得了对福美双敏感的三株突变株Ｔ４６Ｎ１０、Ｔ４６Ｎ７和Ｔ４６Ｎ１７。利用这三个突变株作受体，通过基因克隆的方法筛选到了可使三个突变株恢复抗性的克隆，抗性基因分别被定位在７ｋｂ、２．５ｋｂ和２０ｋｂ的ＥｃｏＲⅠ片段上。将这三个克隆分别用（３２）Ｐ标记后制成分子探针，然后分别与三个突变菌株的总ＤＮＡ进行ＤＮＡ－ＤＮＡ分子杂交，结果表明，各突变株均存在与菌株Ｔ４６的抗福美双基因克隆的高度同源性，经结合形态、生理生化等分析后证实这三株突变株均源自于出发菌株Ｔ４６。