Induced pluripotent cell mass plays a role in genetic transformation mediated by Agrobacterium. Mature seeds are more recalcitrant to the induction of suitable calli than immature embryos in rice, but the exact molecu...Induced pluripotent cell mass plays a role in genetic transformation mediated by Agrobacterium. Mature seeds are more recalcitrant to the induction of suitable calli than immature embryos in rice, but the exact molecular mechanisms involved remain elusive. In this study, the morphological structure of calli induced from mature seeds and immature embryos were observed under a scanning electron microscope using a paraffin embedded technique. Meanwhile, a total of 2 173 up- and down-regulated genes were identified in calli induced from mature seeds and immature embryos by RNA-seq technique and furtherly confirmed by quantitative real-time PCR. The results revealed the remarkable morphological differences in calli induced from mature seeds and immature embryos, and plant hormone signal transduction and hormone biosynthesis pathways, such as abscisic acid, salicylic acid and jasmonic-isoleucine, were found to play roles in somatic embryogenesis. This study provided comprehensive gene expression sets for mature seeds and immature embryos that were served as an important platform resource for further functional studies in plant embryogenesis.展开更多
Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studi...Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studies are performed without regarding dimple and spring of spacer grids,just considering mixing vane.Moreover,these studies use k-ε turbulence model without considering the suitability of the other turbulence models upon the different spacer grids flow.A study is carried out to understand the 3-D single-phase flow in AFA-2G 5×5 rod bundles with spacer grids based on numerical method.In order to investigate the suitability of different turbulence models,k-ε model and k-ω model,the influence of different parts of spacer grid on the fluid flow is also predicted.By using second-order upwind scheme,hybrid grids technique,and improved SIMPLEC algorithm,the Reynolds averaged mass conservation and momentum conservation equations are solved,and the pressure and velocity field of flow are obtained.The numerical simulation results are compared with experiment results and the agreement is satisfactory.The simulation results show the influences of the spring,dimple and mixing vane,and the different characteristics of the k-ε model and k-ω model.Comparing with the experiment results,the simulation results suggest that the k-ω model is suitable for the simulation of the rod bundle flow with spacer grids;the spring and dimple are the main causes of the pressure loss in the spacer grid channel.The friction coefficient of the channel with spring and dimple is 1.5 times the coefficient of the channel with the vane.These results are beneficial to enhance the simulation ability of spacer grids flow and optimization design ability of spaces grid.展开更多
基金supported by grants from the Hi-tech Research and Development(863)Program of China(Grant Nos.2014AA10A603 and 2014AA10A604)the National Major Projects of Cultivated Transgenic New Crop Varieties Foundation of China(Grant Nos.2016ZX001006 and 2016ZX08001004)the Special Foundation of Non-Profit Research Institutes of Fujian Province,China(Grant No.2015R1021-7)
文摘Induced pluripotent cell mass plays a role in genetic transformation mediated by Agrobacterium. Mature seeds are more recalcitrant to the induction of suitable calli than immature embryos in rice, but the exact molecular mechanisms involved remain elusive. In this study, the morphological structure of calli induced from mature seeds and immature embryos were observed under a scanning electron microscope using a paraffin embedded technique. Meanwhile, a total of 2 173 up- and down-regulated genes were identified in calli induced from mature seeds and immature embryos by RNA-seq technique and furtherly confirmed by quantitative real-time PCR. The results revealed the remarkable morphological differences in calli induced from mature seeds and immature embryos, and plant hormone signal transduction and hormone biosynthesis pathways, such as abscisic acid, salicylic acid and jasmonic-isoleucine, were found to play roles in somatic embryogenesis. This study provided comprehensive gene expression sets for mature seeds and immature embryos that were served as an important platform resource for further functional studies in plant embryogenesis.
基金supported by National Key Laboratory of Bubble Physics and Natural Circulation of China(Grant No. 51482040105CB0103)
文摘Spacer grids play an important role in pressurized water reactor（PWR） fuel assembly in that they have significant influence on the thermal-hydraulic characteristics of the reactor core.But so far,the numerical studies are performed without regarding dimple and spring of spacer grids,just considering mixing vane.Moreover,these studies use k-ε turbulence model without considering the suitability of the other turbulence models upon the different spacer grids flow.A study is carried out to understand the 3-D single-phase flow in AFA-2G 5×5 rod bundles with spacer grids based on numerical method.In order to investigate the suitability of different turbulence models,k-ε model and k-ω model,the influence of different parts of spacer grid on the fluid flow is also predicted.By using second-order upwind scheme,hybrid grids technique,and improved SIMPLEC algorithm,the Reynolds averaged mass conservation and momentum conservation equations are solved,and the pressure and velocity field of flow are obtained.The numerical simulation results are compared with experiment results and the agreement is satisfactory.The simulation results show the influences of the spring,dimple and mixing vane,and the different characteristics of the k-ε model and k-ω model.Comparing with the experiment results,the simulation results suggest that the k-ω model is suitable for the simulation of the rod bundle flow with spacer grids;the spring and dimple are the main causes of the pressure loss in the spacer grid channel.The friction coefficient of the channel with spring and dimple is 1.5 times the coefficient of the channel with the vane.These results are beneficial to enhance the simulation ability of spacer grids flow and optimization design ability of spaces grid.
