果啤的研究进展

果啤是最近几年才在国内外尤其是在欧洲迅速流行起来的饮料产品。它既具有啤酒的风味,又有果蔬的营养与芳香,加之其酒精度较低,可满足不同层次消费者的需求。介绍了国内果啤发展的三个阶段,并介绍了果啤的研究现状及发展趋势。     

Chemical Communication in Chagas Disease Vectors. Source, Identity, and Potential Function of Volatiles Released by the Metasternal and Brindley's Glands of Triatoma infestans Adults

Compounds from the metasternal and Brindley's glands of the blood-sucking bug, Triatoma infestans, were identified by solid phase microextraction (SPME) and gas chromatography-mass spectrometry. Volatile compounds released by adult bugs during copulation or after mechanical disturbance were also characterized. Six compounds were identified and found consistently in all samples from metasternal glands. The most abundant were 3-pentanone, 2-methylbutanol, 3-pentanol, and an unidentified compound. The metasternal gland blends did not differ qualitatively between sexes. Compounds found in Brindley's glands were short chain acids, alcohols, esters, and a ketone with no qualitative differences between sexes. Isobutyric acid was the main component of this blend, and two new confirmed compounds were described as products of these glands: 2-butanone and 2-methylbutyric acid. 3-Pentanone was collected from the headspace over 33% of the copulating pairs of T. infestans. Volatiles found in the headspace of disturbed T. infestans adults included short-chain fatty acids, alcohols, esters, and ketones, with no qualitative differences between sexes. Both types of glands apparently discharge their contents after disturbance. However, most of the volatiles released by bugs after disturbance came from Brindley's glands. The locomotor activity of fourth instars increased significantly after stimulation with the odors emitted by disturbed adults, as compared with larvae stimulated by the odor of undisturbed adults or by clean air. We also studied the directional behavioral response of fifth instars to the disturbance scent in a locomotion compensator. Larvae exposed to volatiles released by disturbed adults walked away from the direction of the odor. The results suggest that this blend or part of it functions as an alarm pheromone for T. infestans. We suggest that the metasternal glands of this species are involved both in the sexual and the alarm contexts, and that the Brindley's glands probably have both alarm and defensive roles.     

Consumption and Metabolism of 1,2-Dimethoxy-4-(3-Fluoro-2-Propenyl)Benzene, a Fluorine Analog of Methyl Eugenol, in the Oriental Fruit Fly Bactrocera dorsalis (Hendel)

Methyl eugenol (ME) is a natural phenylpropanoid highly attractive to oriental fruit fly Bactrocera dorsalis (Hendel) males. The flies eagerly feed on ME and produce hydroxylated metabolites with both pheromonal and allomonal functions. Side-chain metabolic activation of ME has long been recognized as a primary reason for hepatocarcinogenicity of this compound on rodents. In an attempt to develop a safer alternative to ME for fruit fly management, we developed a fluorine analog 1,2-dimethoxy-4-(3-fluoro-2-propenyl)benzene (I), which, in earlier field tests, was as active to the oriental fruit fly as ME. Now we report that B. dorsalis males are not only attracted to, but also eagerly consume (up to ∼1 mg/insect) compound I, thus recognizing this fluorinated benzene as a close kin of the natural ME. The flies metabolized the fluorine analog I in a similar fashion producing mostly two hydroxylated products, 2-(3-fluoro-2-propenyl)-4,5-dimethoxyphenol (II) and (E)-coniferyl alcohol (III), which they stored in rectal glands. However, the introduction of the fluorine atom at the terminal carbon atom of the double bond favors the ring hydroxylation over a side-chain metabolic oxidation pathway, by which coniferyl alcohol is produced. It also appears that fluorination overall impedes the metabolism: at high feed rate (10 μl per 10 males), the flies consumed in total more fluorine analog I than ME but were unable to metabolize it as efficiently as ME.     

小鼠先天性心脏畸形动物模型的建立

目的：利用丙戊酸（VPA;2-propyl-pentanoic acid）干扰孕鼠子宫内胚胎的发育,致胎鼠心脏发育畸形〔1,2〕,为探讨先天性心脏病的发病机制建立可靠的动物模型。方法：妊娠第6,7,8,9天的ICR孕鼠腹腔注射VPA（700mg/kg）为时间处理组;妊娠第7天的ICR孕鼠腹腔注射200mg/kg,400mg/kg,600mg/kg,700mg/kg的VPA,为处理组;腹腔注射0.9%Nacl为对照组;观察胎鼠心脏畸形发生率。结果：第6,7,8,9天孕鼠在VPA作用后,胎鼠心脏畸形发生率均明显高于对照组（p〈0.05）,以第7天孕鼠组的胎鼠心脏畸形发生率20.90%为最高。第7天孕鼠用200mg/kg,400mg/kg,600mg/kg,700mg/kgVPA腹腔注射后,胎鼠心脏畸形发生率均高于对照组（p〈0.05,以700mg/kg剂量为最高。结论：VPA可致胎鼠心脏发育畸形,以孕期第七天,700mg/kg剂量胎鼠心脏畸形发生率为最高。     

用于果蔬内部品质无损检测的NIRS技术新进展

文中对近红外光谱在水果和蔬菜内部品质检测研究中的最新进展进行了介绍,总结了光谱检测和光谱信号处理中新颖技术的应用及便携式检测系统的发展状况,分析了近红外光谱技术在果蔬内部品质检测中存在的问题和发展方向.     

基于花期果树冠层光谱反射率的果树树种辨识研究

利用冠层光谱反射率数据(Rλ),对处于开花期的7种果树的树种进行了辨识研究.通过光谱数据重采样、植被指数求算等相关数据处理,比较了6种卫星传感器与4种植被指数对果树树种的辨识效能,并在优选数据形式、优化模型参数的基础上,建立了辨识果树树种的BP神经网络模型.主要结论为:(1)6种卫星传感器辨识果树树种的效能由强到弱的排列顺序为:MODIS、ETM+、QUICKBIRD、IKONOS、HRG、ASTER;(2)在4种植被指数中,RVI对果树树种的辨识效能最强,其次是NDVI,SAVI与DVI的辨识效能相对较弱;(3)用MODIS或ETM+传感器的近红外通道与蓝光通道上的反射率数据,求算的RVI与NDVI对果树树种的辨识效能相对较强;(4)在Rλ及其22种变换数据中,波长间隔设为9nm的d1[log(1/Rλ)],是建立BP神经网络模型的首选数据形式.     

应力场对缺陷隧道承载力影响的模型试验研究

隧道在施工及使用过程中结构的稳定性受众多因素影响,但最重要的影响因素归纳起来主要有两点:岩体条件及应力条件.同时,公路隧道在建设过程中由于受施工条件等诸多因素限制而易造成衬砌厚度不足,而对于存在缺陷的隧道受上述因素的影响研究目前尚不多见.基于此,以重庆市在建的笔架山隧道为现场原型,在室内采用几何比为1:25的大比例模型试验,全面研究结构在相同缺陷、不同围岩、不同地应力场作用下,隧道产生病害的形式、规律以及承载力的大小,得出不同围岩条件下地应力场对结构承载力的影响程度大小的结论,以期为今后的维修加固提供指导依据.     

食品防腐剂对菌落总数检测影响的研究

研究几种常用食品防腐剂对风味饮料、果汁饮料菌落总数检测可能存在的影响。结果表明,食品防腐剂在使用限量范围内,样品菌落总数检测结果与对照样菌落总数检测结果没有显著性差异,因此可以认为,食品防腐剂不会对菌落总数检测产生影响。     

黄金梨与鸭梨果实成熟期糖和酸含量变化的研究

梨果实的各种营养物质在整个发育成熟过程中各阶段的变化不同。以黄金梨和鸭梨为试材,两个品种表现出相同的变化规律,可溶性糖、果糖、葡萄糖、蔗糖含量在果实成熟过程中均呈上升趋势,可滴定酸含量呈先上升后下降的变化趋势。     

瓜蒌籽粗蛋白的提取研究

主要研究碱提法与盐提法对瓜蒌籽粗蛋白质的提取工艺。结果表明:通过实验,当碱提取条件为:碱液浓度2%、固液比1∶20、提取温度70℃、提取时间60min时,蛋白质得率最高。