• 제목/요약/키워드: Nuclear transformation

검색결과 179건 처리시간 0.026초

Mannose-Based Selection with Phosphomannose-Isomerase (PMI) Gene as a Positive Selectable Marker for Rice Genetic Transformation

  • Penna, Suprasanna;Ramaswamy, Manjunatha Benakanare;Anant., Bapat Vishvas.
    • Journal of Crop Science and Biotechnology
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    • 제11권4호
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    • pp.233-236
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    • 2008
  • A positive selectable marker system was adapted for transformation of mature embryo-derived calli of Indica rice (Oryza sativa L.) utilizing the PMI gene encoding for phosphomannose-isomerase that converts mannose-6-phosphate to fructose-6-phosphate. The transformed cells grew on medium supplemented with 3% mannose as carbon source and calli were selected on media containing various concentrations of mannose. Molecular analyses showed that the transformed plants contained the PMI gene. The results indicate that the mannose selection system can be used for Agrobacterium-mediated transformation of mature embryo in rice to substitute the use of conventional selectable markers in genetic transformation.

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A simple data assimilation method to improve atmospheric dispersion based on Lagrangian puff model

  • Li, Ke;Chen, Weihua;Liang, Manchun;Zhou, Jianqiu;Wang, Yunfu;He, Shuijun;Yang, Jie;Yang, Dandan;Shen, Hongmin;Wang, Xiangwei
    • Nuclear Engineering and Technology
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    • 제53권7호
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    • pp.2377-2386
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    • 2021
  • To model the atmospheric dispersion of radionuclides released from nuclear accident is very important for nuclear emergency. But the uncertainty of model parameters, such as source term and meteorological data, may significantly affect the prediction accuracy. Data assimilation (DA) is usually used to improve the model prediction with the measurements. The paper proposed a parameter bias transformation method combined with Lagrangian puff model to perform DA. The method uses the transformation of coordinates to approximate the effect of parameters bias. The uncertainty of four model parameters is considered in the paper: release rate, wind speed, wind direction and plume height. And particle swarm optimization is used for searching the optimal parameters. Twin experiment and Kincaid experiment are used to evaluate the performance of the proposed method. The results show that the proposed method can effectively increase the reliability of model prediction and estimate the parameters. It has the advantage of clear concept and simple calculation. It will be useful for improving the result of atmospheric dispersion model at the early stage of nuclear emergency.

MODELING OF THE BAINITE TRANSFORMATION KINETICS IN C-MN-MO-NI STEEL WELD CGHAZ

  • Sangho Uhm;Lee, Changhee;Kim, Joohak;JunhwaHong
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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    • pp.276-281
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    • 2002
  • A metallurgical model for bainite transformation kinetics in the coarse-grained heat affected zone(CGHAZ) on the basis of an Avrami-type equation was studied. Isothermal transformation tests were carried out to obtain the empirical equations for incubation time and Avrami kinetic constants for C-Mn-Mo-Ni steel. The effect of prior austenite grain size(PAGS) on the reaction rate of bainite was also investigated. Compared with experimental transformation behavior of bainite, the predicted behavior was in good agreement. It was also found that a smaller grain size retard the bainite reaction rate, contrary to the classical grain size effect and this is considered to be caused by constraint of grain size to bainite growth.

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Modeling of the Bainite Transformation kinetics in C-Mn-Mo-Ni Steel weld CGBAZ

  • Uhm, S.;Lee, C.;Kim, J.;Hong, J.
    • International Journal of Korean Welding Society
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    • 제2권1호
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    • pp.11-14
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    • 2002
  • A metallurgical model for bainite transformation kinetics in the coarse-grained heat affected zone(CGHAZ) on the basis of an Avrami-type equation was studied. Isothermal transformation tests were carried out to obtain the empirical equations for incubation time and Avrami kinetic constants for C-Mn-Mo-Ni steel. The effect of prior austenite grain size(PAGS) on the reaction rate of bainite was also investigated. Compared with experimental transformation behavior of bainite, the predicted behavior was in good agreement. It was also found that a smaller grain size retard the bainite reaction rate, contrary to the classical grain size effect and this is considered to be caused by constraint of grain size to bainite growth.

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DISCUSSION ABOUT HBS TRANSFORMATION IN HIGH BURN-UP FUELS

  • Baron, Daniel;Kinoshita, Motoyasu;Thevenin, Philippe;Largenton, Rodrigue
    • Nuclear Engineering and Technology
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    • 제41권2호
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    • pp.199-214
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    • 2009
  • High burn-up transformation process in low temperature nuclear fuel oxides material was observed in the early sixties in LWR $UO_2$ fuels, but not studied in depth. Increasing progressively the fuel discharge burn-up in PWR power plants, this material transformation was again observed in 1985 and identified as an important process to be accounted for in the fuel simulations due to its expected consequence on fuel heat transfer and therefore on the fission gas release. Fission gas release was one of the major concerns in PWR fuels, mainly during transient or accidents events. The behaviour of such a material in case of rod failure was also an important aspect to analyse. Therefore several national and international programs were launched during the last 25 years to understand the mechanisms leading to the high burn-up structure formation and to evaluate the physical properties of the final material. A large observations database has been acquired, using the more sophisticated techniques available in hot cells. This large database is discussed in this paper, providing basis to build an engineering-model, which is based on phenomenological description data and information accumulated. In addition this paper has the ambition to construct the best logical model to understand restructuring.