稀有鮈鲫脑芳香化酶cDNA片段的克隆与表达分析

芳香化酶(P450arom)是雌激素合成过程中的关键酶,在性别分化中起重要作用。鱼类存在卵巢性和脑型两种芳香化酶,分别由Cyp19a和Cyp19b编码。稀有鮈鲫作为我国特有的实验动物,尚无其芳香化酶的有关资料,其性别分化机制亦不清楚。本研究采用RT-PCR的方法以简并引物扩增了稀有鮈鲫脑型芳香化酶基因Cyp19b的部分序列,其长度为1070bp,编码357个氨基酸残基,具有典型的芳香化酶结构域。RT-PCR分析发现该基因主要在稀有鮈鲫的脑中表达,在性腺、肠、肾中也有表达;其在雌、雄脑中的表达差异不显著。在

CFD modeling of single-phase flow in a packed bed with MRI validation

Computational fluid dynamics (CFD) simulations are becoming increasingly widespread with the advent of more powerful computers and more sophisticated software. The aim of these developments is to facilitate more accurate reactor design and optimization methods compared to traditional lumped-parameter models. However, in order for CFD to be a trusted method, it must be validated using experimental data acquired at sufficiently high spatial resolution. This article validates an in-house CFD code by comparison with flow-field data obtained using magnetic resonance imaging (MRI) for a packed bed with a particle-to-column diameter ratio of 2. Flows characterized by inlet Reynolds numbers, based on particle diameter, of 27, 55, 111, and 216 are considered. The code used employs preconditioning to directly solve for pressure in low-velocity flow regimes. Excellent agreement was found between the MRI and CFD data with relative error between the experimentally determined and numerically predicted flow-fields being in the range of 3-9%. © 2012 American Institute of Chemical Engineers (AIChE).