Reference Gene Selection for Quantitative PCR Studies in Sheep Neutrophils

Reference genes are essential for studying mRNA expression with quantitative PCR (qPCR). We investigated 11 potential neutrophil reference genes (RPL19, GAPDH, ACTB, B2M, HPRT, G6PD, TFRC, PGK1, YWHAZ, SDHA and GYPC) for sheep under disease conditions of foot rot (FR) and with or without Se supplementation. Initial screening was based on gene expression level (<28 Cq cycles) and variability (SD < 1.5 Cq cycles) and excluded TFRC, GYPC and HPRT from further analysis. Expression stability of the remaining genes was evaluated using four software programs: geNorm, NormFinder, BestKeeper and the comparative delta Cq method. The neutrophil reference genes, G6PD, YWHAZ, GAPDH, RPL19 and SDHA, consistently ranked among the top five most stable genes under these experimental conditions. The SDHA gene expression was not stable in FR-diseased sheep receiving Se treatment and, thus, cannot be recommended as a reference gene. The commonly used genes, PGK1, ACTB and B2M, were not reliable reference genes, underscoring the need to validate neutrophil reference genes under different experimental conditions. Multiple references genes rather than a single gene may provide more robust and reliable results. The best pair of reference genes was SDHA/G6PD in healthy sheep and GADPH/YWHAZ in FR-diseased sheep.     

铁粉形状对硅橡胶复合材料电性能的影响

通过磁场辅助硫化工艺,制备了微米铁粉填充和排列的硅橡胶导电复合材料,比较了铁粉形状对材料组织和电性能的影响.测量结果发现,经过磁场处理的粒状铁粉体系渗流阈值为5%,最小电阻为106Ω,而纤维状铁粉体系渗流阈值仅为0.2%,最小电阻低于1Ω;前者在1010Ω前后出现正压阻效应和负压阻效应,而后者只出现负压阻效应.研究显示,纤维铁粉有较大的长径比,其排列组织的轴向导电性、抵抗变形能力大大优于粒状铁粉,因此决定了它们的复合材料电学性能的差异.     

矿山酸性废水预测评价方法

酸性矿山废水是全球矿山面临的最严重的环境问题之一,预测酸性矿山废水对于预防、控制和治理金属矿山环境污染问题具有重要意义。目前预测方法分为现场短期实验、实验室静态评价、实验室动态评价和现场,文章探讨了静态评价和动态评价两类方法的优、缺点,并提出了进一步的研究设想。     

国外酸性矿山废水管理计划概述

酸性矿山废水中的重金属污染常导致严重的环境问题。文章综述了国外酸性矿山废水管理计划概况,重点介绍了国际酸预防组织发布的《全球酸性岩石废水指南》,其主要内容包括酸性矿山废水调查表征、预测、预防、监测、治理和管理绩效等方面,同时针对我国酸性矿山废水管理存在的问题,提出相关建议。     

内蒙古维拉斯托大型斑岩型锡多金属找矿勘查及启示

维拉斯托锡多金属矿床产于大兴安岭多金属成矿省南段,是近年来在中国北方发现的规模最大的以锡为主的斑岩型矿床。通过系统梳理和归纳维拉斯托锡多金属矿床区域构造背景、地质特征、矿床和矿脉展布特征,重点论证了锡多金属矿化与矿田范围内的时空格架,初步总结了找矿勘查模式。野外地质勘查及研究表明：锡多金属主要构成“地下室＋楼阁”样式,即深部是以锡-锌-铷-铌-钽等成矿元素为主体的强云英岩化、天河石化石英斑岩型矿体;中部产出以锡-铜-锌成矿元素为主的隐爆角砾岩型矿（化）体;浅部为石英脉型锡-钨-锌-铜-钼-银脉型、网脉型矿体,具有叠加成矿的特征。根据找矿勘查经验,其构造-岩浆控矿明显,特征性的矿化蚀变和物化探异常是找矿的主要标志,也为在兴蒙造山带寻找同类型矿床提供了有益的启示。