Host selection byHylemya antiqua (Meigen)

Volatile components ofAllium cepa L, trapped in and recovered from Porapak Q, were separated by gas-liquid and thin-layer chromatography. Fractions eliciting oviposition fromHylemya antiqua (Meigen) were analyzed by combined gas chromatography-mass spectroscopy (GC-MS) and were found to contain saturated and unsaturated disulfides. Authentic samples of the identified components were obtained by synthesis and tested for oviposition response byH.antiqua. Three new attractants and oviposition stimulants forH. antiqua are methyl propyl disulfide,cis-propenyl propyl disulfide, andtrans-propenyl propyl disulfide. All were present in greater proportion in the volatiles from fresh onions than from stored onions. Dimethyl disulfide, methylcis-propenyl disulfide, and methyltrans-propenyl disulfide did not elicit significant oviposition fromH. antiqua.Diptera: Anthomyiidae.Research supported by National Research Council of Canada, Operating Grant Nos. A3881 and A3706, and Cooperative Grant No. A0243: Nature Products Chemistry and Chemical Ecology of Canadian Insect and Disease Pests.     

Identification of feeding stimulants for boll weevils from cotton buds and anthers

Column chromatography of the pentane extract of freeze-dried cotton buds or anthers yielded a wax-sterol ester fraction that exhibited potent feeding stimulant activity for the cotton boll weevil. The waxes of the wax-sterol ester mixture were responsible for the feeding activity. Saponification of the wax-sterol ester fraction yielded about 15% alcohols and 85% sterols. A C₁₈₁ alcohol, dihydrophytol, phytol, and geranylgeraniol constituted 15, 36, 26, and 23%, respectively, of the total alcohols, implicating certain of their long-chain esters as feeding stimulants. Several esters of dihydrophytol, phytol, and geranylgeraniol were identified among the waxes by GC-MS. Certain phytol, geranylgeraniol, and oleyl alcohol esters containing C₁₂ to C₂₆ acid moieties were synthesized and were found to induce high feeding stimulant activity in the cotton boll weevil.In cooperation with the Mississippi Agricultural and Forestry Experiment Station.     

温度对食品级PVC中4种增塑剂迁移量的影响

以食品包装材料聚氯乙烯(PVC)为研究对象,研究PVC中邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二异丁酯(DIBP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基)己酯(DEHP)4种增塑剂在30℃～80℃条件下,水、乙酸、乙醇、正己烷4种模拟液中的迁移情况。结果表明,此4种增塑剂都在正己烷的环境下迁移量最大,并且在各种食品模拟液中的迁移量均随温度的升高而增大。     

Monoterpene oviposition stimulants ofDioryctria amatella in volatiles from fusiform rust galls and second-year loblolly pine cones

Volatiles collected on Poropak Q from fusiform rust galls (Cronartium quercuum F. sp.fusiforme) of loblolly pine for 3 hr were better ovi-position stimulants forDioryctria amatella (Hulst) females than extracts of 8-hr collections. GLC analysis of these extracts showed no major differences in relative monoterpene composition, although 8-hr collections contained an unidentified compound not detected in the 3-hr collections. Comparison of volatiles from second-year loblolly pine cones with those from fusiform galls showed that both containeddl--pinene, (–)--pinene, myrcene, and (+)-limonene. Camphene was found in galls only, and relatively large quantities of -phellandrene were identified only from cones. The five major monoterpenes found in the two host substrates were tested in an oviposition bioassay. Eighteen trials using different combinations of these terpenes showed that the combination of -pinene, myrcene, and limonene was as attractive toD. amatella females as all other terpene combinations, including turpentine.Lepidoptera: Pyralidae.     

Conduritols as Oviposition Stimulants for the Danaid Butterfly, Parantica sita, Identified from a Host Plant, Marsdenia tomentosa

Host-plant chemicals responsible for egg-laying by the chestnut tiger butterfly, Parantica sita, were identified from one of its hosts, Marsdenia tomentosa. Ovipositing females responded positively to a methanolic extract of the plant. Solvent partitioning of the extract and oviposition bioassays indicated that the active principle resided in the aqueous fraction. Further activity-directed fractionation of the water-soluble constituents by various forms of column chromatography led to the isolation of several saturated and unsaturated cyclitols together with their glycosides. Of these, conduritol A, a predominant cyclitol present in the plant, moderately stimulated oviposition, while conduritol F 2-O-glucoside, although present in a very small amount, evoked a stronger response from females than conduritol A when tested at the same dose. In contrast, its aglycone, conduritol F, which was also a trace component, was almost inactive by itself. However, the oviposition-stimulatory activity of conduritol A was significantly enhanced when tested in combination with a small quantity of conduritol F. Addition of a small quantity of conduritol F 2-O-glucoside to conduritol A resulted in a substantial elevation in female responses. Consequently, the synergistic action of a large amount of conduritol A and small amounts of co-occurring conduritol F and its glucoside can account for the stimulation of egg-laying by P. sita on M. tomentosa.     

地质聚合物激发剂及其激发原理

激发剂在制备地质聚合物的过程中发挥着重要的作用。首先概述了酸、碱和盐3类激发剂及其激发效果,通过介绍氢氧化钠、氢氧化钾和水玻璃等常用碱激发剂的激发效果,具体分析各类碱激发剂的作用差别。阐述了乙酸、盐酸、硫酸和磷酸等典型的酸激发剂的研究进展,以及硫酸盐、硅酸盐和铝酸盐等作为盐类激发剂的活化能力,在此基础上对3类激发剂的优缺点进行了总结分析。同时通过论述酸、碱和盐3类激发剂的激发原理,进一步表明了3类激发剂都具备激发地聚物原料活性的能力,都能够不同程度地加快地聚体系水化反应进程,显著提高地聚体系的强度。最后,对激发剂在地聚物领域的未来发展作出了展望。     

食品接触材料PVC中塑化剂迁移规律研究及迁移模型建立

运用同位素内标稀释结合气相色谱质谱方法检测PVC中的塑化剂DIBP、DBP、 DEHP和DEHA。以3 %乙酸、10 %、20 %、50 %、95 %乙醇作为食品模拟溶液,在25 ℃及40 ℃条件下对PVC中四种塑化剂的迁移情况进行研究。另外以Fick第二扩散定律为依据建立PVC中塑化剂的迁移规律数学模型。同时评价模型的可行性,从而提供有效的食品安全性评价。