• Title/Summary/Keyword: strain development

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The Effect of Ageing Time and Temperature on the Strain Ageing Behaviour of Quenched Zircaloy-4

  • Rheem, Karp-Soon;Park, Won-Koo;Yook, Chong-Chul
    • Nuclear Engineering and Technology
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    • v.9 no.3
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    • pp.117-123
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    • 1977
  • The strain ageing behaviour of quenched Zircaloy--4 has been studied as a function of ageing time and temperature in the temperature range 523 to 588 K for a short-ageing time of 1 to 52 seconds. At the test conditions, the strain ageing stress increased with ageing time and temperature at a strain rate of 5.55$\times$10$^{-4}$ sec$^{-1}$ . Applying stress on the Quenched Zircaloy-4, the strain ageing effect indicated following two stages: an initial stage having an activation energy of 0.39 ev considered to be due to Snoek type ordering of intersitial oxygen atoms in the stress field of a dislocation and a second stage having an activation energy of 0.60 ev, due to mainly long-range diffusion of oxygen atoms.

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Characterization of a Unique New Strain Named the NFRDI N°1 Rotifer Strain, a Brackish Brachionus Rotifer Collected from a South Korea Coastal Lagoon

  • Jung, Min-Min
    • Fisheries and Aquatic Sciences
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    • v.14 no.4
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    • pp.333-337
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    • 2011
  • A new and a unique Brachionus rotifer was found in Hwajinpo coastal lagoon in Gangwon Province, South Korea. This Brachionus certainly originated from the wild rather than from aquaculture stations because Hwajinpo coastal lagoon has been under rigorous control as a military protected area and therefore could not have been contaminated by aquaculture stations. The new strain was identified as Brachionus rotundiformis based upon its morphological characteristics. The parthenogenetic female of this new rotifer strain typically shows characters similar to those of B. rotundiformis, such as the pot shape of the body, rounded dorsal plate compared with flattened ventral plate, elliptical mictic egg, four frontal spines, six pointed occipital spines, non-nodal foot, two toes, trophi typical of the Brachionus genus with five uncus plates resembling comb teeth, one wide symmetrical manubrium and ramus, and no stiffened spine as is seen in freshwater Brachionus rotifers. Moreover, its lorica was rather small in size compared with other common rotifer strains that serve as live-food organisms (Guam, Thai, and Bali strains). This new and unique Korean brackish rotifer, a B. rotundiformis strain, was therefore named the National Fisheries Research and Development Institute (NFRDI) $N^{\circ}1$ rotifer strain.

Microstructure Evolution of 15Cr ODS Steel by a Simple Torsion Test (단순 전단변형에 의한 15Cr 산화물 분산강화 강의 미세조직 변화)

  • Jin, Hyun Ju;Kang, Suk Hoon;Kim, Tae Kyu
    • Journal of Powder Materials
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    • v.21 no.4
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    • pp.271-276
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    • 2014
  • 15Cr-1Mo base oxide dispersion strengthened (ODS) steel which is considered to be as a promising candidate for high- temperature components in nuclear fusion and fission systems because of its excellent high temperature strength, corrosion and radiation resistance was fabricated by using mechanical alloying, hot isostatic pressing and hot rolling. Torsion tests were performed at room temperature, leading to two different shear strain routes in the forward and reverse directions. In this study, microstructure evolution of the ODS steel during simple shearing was investigated. Fine grained microstructure and a cell structure of dislocation with low angle boundaries were characterized with shear strain in the shear deformed region by electron backscattered diffraction (EBSD). Grain refinement with shear strain resulted in an increase in hardness. After the forward-reverse torsion, the hardness value was measured to be higher than that of the forward torsion only with an identical shear strain amount, suggesting that new dislocation cell structures inside the grain were generated, thus resulting in a larger strengthening of the steel.

Development of Fenvalerate Resistance in the Diamondback Moth, Plutella xylostela Linne (Lepidoptera : Yponomeutidae) and its Cross Resistance (배추좀나방의 Fenvalerate에 대한 저항성 발달과 교차저항성)

  • 김길하;서영식;이준호;조광연
    • Korean journal of applied entomology
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    • v.29 no.3
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    • pp.194-200
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    • 1990
  • The diamondback moth (Plutella xylostella L.) was selected over 24 generations with fenvalerate. The resulting resistant strain was tested to study development of insecticide resistance and cross resistance to some insecticides in the laboratory. Insecticide resistance of diamondback moth at the 24th generation devleoped 66.2 fold compared to the parent strain for fenvalerate. The fenvalerate selected strain exhibited 145 fold, a high level of cross resistance to deltamethrin, and also showed 17.4-45.0 fold cross resistance to alphamethrin, cypermethrin, fenvalerate, permethrin, and tetramethrin in the pyrethroid insecticides. The fenvalerate selected strain showed 2.5-4.3 fold, low cross resistance to diazinon, dichlorvos, EPN, BPMC, cabaryl, and methomyl. However, it did not show cross resistance to acephate, fenitrothion, phenthoate, and carbofuran.

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Current Status and Applications of Adaptive Laboratory Evolution in Industrial Microorganisms

  • Lee, SuRin;Kim, Pil
    • Journal of Microbiology and Biotechnology
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    • v.30 no.6
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    • pp.793-803
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    • 2020
  • Adaptive laboratory evolution (ALE) is an evolutionary engineering approach in artificial conditions that improves organisms through the imitation of natural evolution. Due to the development of multi-level omics technologies in recent decades, ALE can be performed for various purposes at the laboratory level. This review delineates the basics of the experimental design of ALE based on several ALE studies of industrial microbial strains and updates current strategies combined with progressed metabolic engineering, in silico modeling and automation to maximize the evolution efficiency. Moreover, the review sheds light on the applicability of ALE as a strain development approach that complies with non-recombinant preferences in various food industries. Overall, recent progress in the utilization of ALE for strain development leading to successful industrialization is discussed.

Genome analysis of Bacteroides sp. CACC 737 isolated from feline for its potential application

  • Kim, Jung-Ae;Jung, Min Young;Kim, Dae-Hyuk;Kim, Yangseon
    • Journal of Animal Science and Technology
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    • v.62 no.6
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    • pp.952-955
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    • 2020
  • Bacteroides sp. CACC 737 was isolated from a feline, and its potential probiotic properties were characterized using functional genome analysis. Whole-genome sequencing was performed using the PacBio RSII and Illumina HiSeq platforms. The complete genome of strain CACC 737 contained 4.6 Mb, with a guanine (G) + cytosine (C) content of 45.8%, six cryptic plasmids, and extracellular polysaccharide gene as unique features. The strain was beneficial to animal health when consumed as feed, for example, for ameliorating immunological dysfunctions and metabolic disorders. The genome information adds to the comprehensive understanding of Bacteroides sp. and suggests potential animal-related industrial applications for this strain.

Draft Genome Sequence of the Yeast Strain Hormonema macrosporum POB-4, which Produces the Biosurfactant Glycocholic Acid

  • Parthiban Subramanian;Jeong-Seon Kim;Jun Heo;Yiseul Kim
    • Microbiology and Biotechnology Letters
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    • v.51 no.4
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    • pp.531-534
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    • 2023
  • We report the draft genome sequence of the yeast strain Hormonema macrosporum POB-4, capable of producing the biosurfactant glycocholic acid, one of the bile acids. A majority of genes with known function were associated with metabolism and transport of amino acid and carbohydrate as well as secondary metabolites biosynthesis, transport, and catabolism. We observed genes of eleven C-N hydrolases and two CoA transferases which have been reported to be involved in the biosynthesis of glycocholic acid. Further experimental studies can help to elucidate the specific genes responsible for biosurfactant production in strain POB-4.

Studies of the Insecticide Resistance in the Green Peach Aphid, Myzus persicae Sulzer (V). Development of Cypermethrin and Pirimicarb Resistance, and Cross Resistance (복숭아혹진딧물의 살충제 저항성에 관한 연구 (V). Cypermethrin과 Pirimicarb에 의한 저항성 발달과 교류저항성)

  • 최승윤;김길하;안용준
    • Korean journal of applied entomology
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    • v.28 no.1
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    • pp.23-27
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    • 1989
  • The green peach aphid(Myzus pericae Sulzer) was selected over 20 generations with cypermethrin and pirmicarb, respectively. The resulting resistant strains were tested to inverting-ate the development of insecticide resistance and cross-resistance to some insecticides in the laboratory. The development of insecticide resistance against green peach aphid at the 20th selected generation was greatly varied with the insecticides: 20.5 fold for cypermethrin and 3.2 fold for pirimicarb compared with the parent strain. The cypermethrin selected strain exhibited cross resistance to acephate and pirimicarb, and pirimicarb selected strain to acephate and cypermethrin, respectively. Demeton-S-methyl, however, has not been shown cross-resistance by the selected strains.

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Microstructural Evolution during Hot Deformation of Molybdenum using Processing Map Approach (변형지도 모델링을 통한 몰리브데늄의 고온 변형에 따른 미세조직 변화 연구)

  • Kim, Young-Moo;Lee, Sung-Ho;Lee, Seong;Noh, Joon-Woong
    • Journal of Powder Materials
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    • v.15 no.6
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    • pp.458-465
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    • 2008
  • The hot deformation characteristics of pure molybdenum was investigated in the temperature range of $600{\sim}1200^{\circ}C$ and strain rate range of $0.01{\sim}10.0/s$ using a Gleeble test machine. The power dissipation map for hot working was developed on the basis of the Dynamic Materials Model. According to the map, dynamic recrystallization (DRX) occurs in the temperature range of $1000{\sim}1100^{\circ}C$ and the strain rate range of $0.01{\sim}10.0/s$, which are the optimum conditions for hot working of this material. The average grain size after DRX is $5{\mu}m$. The material undergoes flow instabilities at temperatures of $900{\sim}1200^{\circ}C$ and the strain rates of $0.01{\sim}10.0/s$, as calculated by the continuum instability criterion.

Prediction of Liquation Crack Initiation at HAZ of Laser Weldment Based on Strain Analysis at Elevated Temperature

  • Yamamoto, Motomichi;Shinozaki, Kenji;Kitamura, Mitsuru;Shirai, Makoto
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.244-249
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    • 2002
  • The purpose of this study is to develope the prediction method of liquation crack initiation in HAZ of laser weldment. Thermal two dimensional strain analyses were performed by FEM for bead-on-plate welding in order to obtain the plastic strain at elevated temperature in HAZ of the laser weldment. From these results, it became clear that the plastic strain at elevated temperature affected liquation crack initiation in HAZ, and it could be proposed that the critical strain, which controlled liquation crack initiation, existed. Moreover, an attempt was made to develop thermal and dynamic three dimensional strain analysis method for the laser weldment in order to obtain the plastic strain at elevated temperature in HAZ of the laser weldment in more detail and precisely.

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