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H3K27me3 and H3K4me3 Chromatin Environment at Super-induced Dehydration Stress Memory Genes of Arabidopsis thaliana

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Molecular Plant 2014年第3期7卷 502-513页

作者： Ning Liu Michael Fromm Zoya avramova University of Nebraska School of Biological Sciences 1901 Vine Street Lincoln NE 68588 USA University of Nebraska Center for Biotechnology and Center for Plant Science innovation 1901 Vine Street Lincoln NE 68588 USA

Pre-exposure to a stress may alter the plant＇s cellular, biochemical, and/or transcriptional responses during future encounters as a ＂memory＇ from the previous stress. Genes increasing transcription in response to a first dehydra- tion stress, but producing much higher transcript levels in a subsequent stress, represent the super-induced ＇transcription memory＇ genes in Arabidopsis thaliana. The chromatin environment （histone H3 tri-methylations of Lys 4 and Lys 27, H3K4me3, and H3K27me3） studied at five dehydration stress memory genes revealed existence of distinct memory- response subclasses that responded differently to CLF deficiency and displayed different transcriptional activities dur- ing the watered recovery periods. Among the most important findings is the novel aspect of the H3K27me3 function observed at specific dehydration stress memory genes. in contrast to its well-known role as a chromatin repressive mechanism at developmentally regulated genes, H3K27me3 did not prevent transcription from the dehydration stress- responding genes. The high H3K27me3 levels present during transcriptionally inactive states did not interfere with the transition to active transcription and with H3K4me3 accumulation. H3K4me3 and H3K27me3 marks function indepen- dently and are not mutually exclusive at the dehydration stress-responding memory genes.

关键词： dehydration stress-response genes transcription memory genes H3K4me3 and H3K27me3 at memorygenes CLF Arabidopsis thaliana.

Self-healing effect of ceria electrodeposited thin films on stainless steel in aggressive 0.5 mol/L NaCl aqueous solution

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Journal of Rare Earths 2015年第11期33卷 1212-1227页

作者： Desislava Guergova Emilia Stoyanova Dimitar Stoychev ivalina avramova Plamen Stefanov "Rostislaw Kaischew" institute of Physical Chemistry Bulgarian Academy of Sciences institute of General and inorganic Chemistry Bulgarian Academy of Sciences

The self-healing effect of electrochemically deposited CeO2-Ce2O3 films on stainless steel OC404（SS） in 0.5 mol/L NaCl solution was studied. it was established that the corrosion potential of the steel, after covering it with CeO2-Ce2O3 layer and thermal treatment（i.e. potential of the system CeO2-Ce2O3/SSt.t.）, was shifted sharply to a considerably more positive value, while the corrosion current was reduced noticeably. The X-ray photoelectron spectroscopy（XPS）, energy dispersive spectroscopy（EDS） and scanning electron microscopy（SEM） analyses on the observed scratched surface area of the system CeO2-Ce2O3/SSt.t., after exposure of investigated specimens to 0.5 mol/L NaCl corrosion media, showed partial accumulation of ceria, as well as remarkable increase in the concentrations of oxides of Al, Cr and Fe, on the mechanically revealed steel surface. On the basis of the obtained results one could conclude that the secondary passive oxide/hydroxide films, formed after a definite time interval of exposure to corrosion media, acted as barriers, hindering the corrosion processes in active zones. A hypothesis was put forward about the mechanism of self-repairing oxide layers on the steel surface and their corrosion protection effect respectively.

关键词： stainless steel ceria films corrosion self-healing effect rare earths

基于流固共轭传热的两相流动数值模拟及燃料子通道CHF预测研究

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原子能科学技术 2020年第6期54卷 1092-1098页

作者：冯琳娜李权黄永忠刘振海齐飞鹏 M.avramova 中国核动力研究设计院核反应堆系统设计技术重点实验室四川成都610213 北卡罗来纳州立大学美国罗利27695

为对过冷沸腾两相流动进行准确模拟,并探索临界热流密度(CHF)预测方法,本文基于共轭传热和两相C FD分析的方法,通过流固界面耦合,建立流固共轭传热两相流动耦合求解的数值模型.首先通过典型燃料棒栅元过冷沸腾两相流动的模拟,验证数值... 详细信息

为对过冷沸腾两相流动进行准确模拟,并探索临界热流密度(CHF)预测方法,本文基于共轭传热和两相C FD分析的方法,通过流固界面耦合,建立流固共轭传热两相流动耦合求解的数值模型.首先通过典型燃料棒栅元过冷沸腾两相流动的模拟,验证数值模型的正确性.随后对燃料子通道内两相流动进行模拟,并在两相流动模拟的基础上,通过准瞬态的方法,建立与CHF试验过程非常近似的CHF预测方法,将加热壁面的温度飞升作为CHF判定的标准,实现对燃料组件子通道CHF的数值预测.研究表明,本文建立的数值模拟方法,可为燃料组件或其他换热系统的CHF预测奠定基础,为燃料组件的设计提供新的辅助手段.

关键词：共轭传热过冷沸腾两相流动临界热流密度壁面温度

全长尺寸5×5格架棒束通道两相流动特性研究

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核动力工程 2017年第S2期38卷 25-28页

作者：李权 avramova M 刘洋华郑美银赵艳丽陈杰焦拥军于俊崇中国核动力研究设计院核反应堆系统设计技术重点实验室成都610213 北卡罗来纳州立大学核能工程系美国27695 清华大学工程物理系北京100084

采用两相计算流体动力学(CFD)分析的方法,对全长尺寸格架棒束通道内过冷沸腾两相流动进行了数值模拟。将模拟得到的棒束通道中心4个子通道的平均空泡份额与实验值进行对比发现,在高空泡份额区域与实验值符合较好;在低空泡份额区域,计算... 详细信息

采用两相计算流体动力学(CFD)分析的方法,对全长尺寸格架棒束通道内过冷沸腾两相流动进行了数值模拟。将模拟得到的棒束通道中心4个子通道的平均空泡份额与实验值进行对比发现,在高空泡份额区域与实验值符合较好;在低空泡份额区域,计算值略高于实验值。两相CFD方法模拟得到了棒束通道内空泡份额的详细分布,观察到格架上游空泡份额集中在加热棒的周围,但在格架下游,子通道中心的空泡份额增加,加热棒周围的空泡份额减小,间接地证明了格架对临界热流密度(CHF)的提升作用。

关键词：全长尺寸格架过冷沸腾空泡份额

基于两相CFD的非均匀加热圆管CHF预测方法研究

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核动力工程 2019年第3期40卷 6-11页

作者：李权陈平黄永忠陈杰焦拥军于俊崇 Maria avramova 中国核动力研究设计院核反应堆系统设计技术重点实验室成都610213 清华大学工程物理系北京100084 北卡罗来纳州立大学美国27695

为建立非均匀加热工况临界热流密度(CHF)预测方法,以对换热系统的安全分析提供新的辅助手段,本研究采用欧拉两流体模型和壁面沸腾模型,对非均匀加热圆管的CHF进行预测。通过数值计算得到不同热流密度下近壁面空泡份额和壁面温度的分布,... 详细信息

为建立非均匀加热工况临界热流密度(CHF)预测方法,以对换热系统的安全分析提供新的辅助手段,本研究采用欧拉两流体模型和壁面沸腾模型,对非均匀加热圆管的CHF进行预测。通过数值计算得到不同热流密度下近壁面空泡份额和壁面温度的分布,将壁面温度出现二次峰值和此时近壁面空泡份额的峰值位置分别作为CHF发生的依据和CHF发生的点,并用此方法对2种不同功率分布圆管的CHF进行研究。研究结果表明,预测得到临界时的平均热流密度及临界发生的位置都与实验结果符合较好。因此,本研究建立的数值预测方法能够用于非均匀加热圆管CHF的预测。

关键词：临界热流密度(CHF) 非均匀加热空泡份额峰值壁面温度