顶侧双吸油烟机不同进风口结构的吸烟效果分析

顶侧双吸油烟机的进风口结构位于集烟腔上,是影响油烟吸排效果的重要因素。基于有限元仿真对顶侧双吸油烟机的不同进风口结构方案进行了流体仿真分析,探究了各进风口设计方案对吸烟效果的影响。仿真结果表明,上中部均有开口结构的吸烟效果最好,吸烟效率在理论上可以达到97.4%;仅上部有开口结构的吸烟效果最差,吸烟效率仅有80.3%。通过实验验证,结果与仿真结果相符。

Geometric basis:a geometric solving cell for geometric computing

Geometric computing is an important tool in design and manufacturing and in arts. Conventionally, geometric computing is taken by algebraic computing. The vivid intuition of objects in visualization is lost in numeric functions, which is however very useful to human cognition as well as emotion. In this paper, we proposed a concept and theory of geometric basis （GB） as the solving cell for geometric computing. Each GB represents a basic geometric operation. GB works as both expressing and solving cell just like the concept of basis in linear algebra by which every element of the vector space can be expressed. For 3D problems, with a procedure of a projections reduction, the problem can be reduced to plane and the reduction function can be designed as a GB. A sequence of GB can construct a higher layer GB. Then, by the traversal of tree, a sequence of GB is got and this sequence is just the construction process and also the solution of this geometric problem.

慢病毒载体介导的dbpA基因沉默对结直肠癌细胞生物学行为的影响

目的探讨慢病毒介导的RNA干扰(RNA interference, RNAi)沉默DNA结合蛋白dbpA基因对大肠癌细胞生物学行为的影响。方法实验分为3组:siRNA-dbpA慢病毒干扰组、非特异性序列组和空白对照组。制备siRNA-dbpA慢病毒表达载体,转染SW620后,采用RT-PCR法对细胞中dbpA mRNA表达水平进行分析,Western blot检测SW620细胞的dbpA蛋白表达水平。采用流式细胞仪检测细胞凋亡和细胞周期变化,MTT法检测细胞增殖抑制率,并检测细胞克隆形成能力。通过裸鼠移植瘤实验观察沉默dbpA后SW620细胞在体内成瘤能力。结果siRNA-dbpA显著下调了 SW620细胞中dbpA的表达,所构建的重组慢病毒有较高的基因沉默效率。siRNA-dbpA组的dbpA表达水平下调。各组的细胞凋亡率分别为26. 6%±0. 38%,12. 54%± 0. 25%和4. 46%± 0. 19%,siRNA-dbpA组高于其他两组,差异有统计学意义(F = 28. 159,P <0.01);各组的细胞增殖第5天吸光度值分别为(0. 194 ±0. 037),(0. 814 ± 0. 043)、( 1.625 ±0.061), siRNA-dbpA 组低于其他两组,差异有统计学意义(F = 23.214,P<0.01);细胞克隆数分别为(37±3)、(64±5)和(175 ±10)个,siRNAdbpA组低于其他两组,差异有统计学意义(F = 40. 254,P <0. 01)。siRNA-dbpA组裸鼠移植瘤体积在14.21,35 d后与非特异性序列组和空白对照组相比差异均有统计学意义(F= 38. 256、40. 241、30.257,均P<0.05)。结论以dbpA为靶标的RNA干扰能下调大肠癌细胞株SW620中的dbpA表达,显著增加细胞的凋亡,降低了细胞的增殖克隆能力。dbpA沉默后对活体肿瘤细胞的生长有明显的抑制作用。