Epidemiology of Bovine Venereal Campylobacteriosis: Geographic Distribution and Recent Advances in Molecular Diagnostic Techniques

Bovine venereal campylobacteriosis (BVC) is a major cause of economic loss to the cattle industries in different parts of the world. Camplylobacter fetus subsp. venerealis (Cfv), the main causative agent of BVC, is highly adapted to the genital tract of cattle and is transmitted by carrier bulls. However, infertility and abortions can also be caused by the intestinal pathogens C. fetus subsp. fetus (Cff), and C. jenuni, which are not venereally transmitted. Bovine venereal campylobacteriosis, caused by Cfv associated with lowered fertility, embryo mortality and abortion, repeated returns to service, reduced pregnancy rates and extended calving intervals, has the highest prevalence in developing countries where natural breeding in cattle is widely practised. The epidemiology, pathogenesis and diagnosis of the disease have been the subject of previous reviews. The main focus of this review is to highlight the epidemiology of this disease with particular reference to geographical distribution and recent advances in molecular diagnostic techniques. It is hoped that further research interest of scientists will be stimulated with a view to finding lasting solutions to the reproductive problems associated with the disease for better livestock productivity, particularly in developing endemic countries.     

背负式静电喷雾器的设计研究

介绍了静电喷雾技术在植物保护施药中的应用,以及国内外该项技术的发展趋势;阐述了背负式静电喷雾器的设计思路、方案及研究过程,最后简要介绍了背负式静电喷雾器的特点及不足之处.     

Visualization of three-dimensional chaos

Most chaotic mixing experiments have been restricted to two-dimensional, time-periodic flows, and this has shaped advances in theory as well. A prototypical, bounded, three-dimensional flow with a moderate Reynolds number is presented; this system lends itself to detailed experimental observation and allows for high-precision computational inspection. The flow structure, captured by means of cuts with a laser sheet (experimental Poincare section), was visualized with the use of continuously injected fluorescent dye streams and revealed detailed chaotic structures with high-period islands.     

杏贮藏保鲜技术研究进展

概述了杏的生产现状,对影响杏贮藏效果的因素、贮期主要病害及防治方法、目前普遍采用的杏贮藏保鲜技术进行归纳,并展望今后杏贮藏保鲜技术的发展方向.     

鱼类消化酶活性及其影响因素的研究进展

鱼类消化酶是鱼类消化生理研究的重要内容,随着水产养殖业的发展,鱼类消化生理及其影响因素日益受到人们的重视.综述了鱼类消化酶的分布,以及各种因素对消化酶活性的影响,并重点阐述了近年来广泛研究的各种营养因素与鱼类消化酶活性的关系.     

药物基因组学科研合作网络的统计学性质

药物基因组学是一门年轻的学科领域。该领域内相关科学研究工作者之间形成的科研合作关系网络,也具有类似许多大型合作关系网络数据库所具有的无尺度网络特性,其非连通合作网络内部具有较大连通组群的聚类特性和小世界特征等相关性质。     

Variation in phenolic content and antioxidant activity of fermented rooibos herbal tea infusions: role of production season and quality grade

Data are required to calculate the dietary exposure to rooibos herbal tea flavonoids and phenolic acids. Representative content values for the principal phenolic compounds and total antioxidant capacity of fermented rooibos infusion, taking into account variation caused by production seasons (2009, 2010, and 2011) and quality grades (A, B, C, and D), were determined for samples (n = 114) from different geographical areas and producers. The major phenolic constituents were isoorientin and orientin (>10 mg/L), with quercetin-3-O-robinobioside, phenylpyruvic acid glucoside, and aspalathin present at >5 mg/L. Isovitexin, vitexin, and hyperoside were present at <3 mg/L. Rutin, ferulic acid, and isoquercitrin were present at <2 mg/L. Nothofagin was present at <1 mg/L. Only traces of luteolin-7-O-glucoside and the aglycones quercetin, luteolin, and chrysoeriol were present. Substantial variation was observed in the individual content values of the phenolic compounds and total antioxidant capacity within production seasons and quality grades.