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Synthesis and luminescent properties of a new green $CaZrO_3:\;HO_{3+}$ long persistent phosphors (녹색 발광의 $CaZrO_3:\;HO_{3+}$ 축광성 형광체의 합성 및 발광 특성)

  • Park, Byeong-Seok;Choi, Jong-Keon
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.18 no.3
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    • pp.109-114
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    • 2008
  • Novel green long persistent phosphors of $CaZrO_3$ : $HO_{3+}$ have been synthesized at high temperature with weak reduction atmosphere by traditional solid state reaction method. The role of $H_3BO_3$ as flux and the suitable concentration of Ho as activator on the $CaZrO_3$ : $HO_{3+}$ long persistent phosphors has been investigated. Crystals of $HO_{3+}$ doped $CaZrO_3$ long persistent phosphores were characterized by fluorescence spectrophotometer and photoluminescence (PL). The main emission spectra of 546 nm peak was revealed through synthesizing at high temperature in $N_2$ gas atmosphere. The after glow emission spectra of $CaZrO_3$ : $HO_{3+}$ long persistent phosphores arise at 546 nm peak of narrow range. because that revealed pure green color. Green long persistent phosphors have been observed in the system for over 5 h after UV irradiation (254 nm). The main emission peak was ascribed to $HO_{3+}$ ions transition from $^5F_4$, $^5S_2{\to}^5I_3$, and the after glow may be ascribed to the trap centers in the $CaZrO_3$ host lattice.

Activation of RAW 264.7 Macrophage by Digested Bacterial Cell of Pig-derived Lactobacillus Strains (돼지에서 분리된 Lactobacillus Strains의 균체분해산물에 의한 RAW 264.7 Macrophage 활성화)

  • Kim, D.W.;Cho, S.B.;Jeong, H.Y.;Moon, H.G.;Lee, H.J.;HwangBo, J.;Chung, W.T.;Choi, C.W.;Chung, I.B.
    • Journal of Animal Science and Technology
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    • v.47 no.6
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    • pp.947-954
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    • 2005
  • This study was conducted to investigate the effects of hydrolyzed Lactobacillus supplementation with digestive enzymes treatment on the macrophage activation, the induction of nitric oxide(NO), interleukin (IL)-6 and tumor necrosis factor(TNF)-$\alpha$. The RAW 264.7 murine macrophage was exposed to porcine Lactobacillus strains which were digested with both pepsin and pancreatin. The production of NO, TNF-$\alpha$ and IL-6 in the macrophage were strain and dose-dependent, respectively. The induction of NO and cytokines were higher in both 3149 and 3146 strains compared with other Lactobacillus strains. Overall, the level of NO was observed at the lower range between 10 and 150 μg hydrolysates per ml, whereas IL-6 and TNF-$\alpha$ were observed at relatively higher concentration between 50 and 300 μg hydrolysates per ml. Lactobacillus strains which produced a high level of NO also showed a high induction of TNF-$\alpha$ and IL-6. Therefore, the present results suggest that hydrolysates of Lactobacillus strains are related to induction of several macrophage mediators, and then it could be beneficially used to modulate gastrointestinal immune function of the host. Also, the methodogly employed in this study might be useful to investigate the effects of lactic acid bacteria on gastrointestinal immunity.

Morphology, Phylogeny and Ecology of Hyphomycetes Hyperparasitic to Rusts

  • Park, Mi-Jeong;Park, Jong-Han;Hong, Seung-Beom;Shin, Hyeon-Dong
    • 한국균학회소식:학술대회논문집
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    • 2015.05a
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    • pp.55-55
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    • 2015
  • Rust is one of the most destructive diseases on economically important plants such as agricultural and horticultural crops, as well as forest trees [1]. Chemical treatment is the most effective means to control rust, but use of the chemical fungicides involves inevitable risks to human health and environment [2]. Unfortunately, biocontrol is currently impracticable for rust disease management [3]. It is necessary to exploit biocontrol agents to help prevent rust diseases. As a fundamental research for future development of biocontrol agents for rusts, biodiversity of hyperparasites occurring on rust fungi was investigated. During 2006-2010, 197 fungal isolates of the rust hyperparasites were collected and isolated from various combinations of mycohosts and plant hosts in many regions of Korea. Based on morphological and molecular data, they were identified as 8 genera and 12 species. Besides, phylogenetic relationships between the hyperparasites and related taxa were inferred. A total of 114 isolates of Pseudovirgaria were obtained from rust pustules of Phragmidium spp. and Pucciniastrum agrimoniae infecting rosaceous plants. Phylogenetic analysis using multigene sequences revealed a high level of genetic variability among many isolates of Pseudovirgaria and close correlation between the isolates and mycohosts. Only two species of Pseudovirgaria, P. hyperparasitica and P. grisea are often difficult to distinguish by their morphological similarity, but on the molecular basis they were clearly differentiated from each other. There had been no previous record of P. grisea outside Europe, but the present study has proved its presence in Korea. Among six distinct groups (five of P. hyperparasitica and one of P. grisea) within the Pseudovirgaria isolates, each lineage of P. hyperparasitica was closely associated with specific mycohosts and thus might have cospeciated with their mycohosts, which probably led to coevolution. Although P. grisea possesses a host preference for Phragmidium species occurring on Rubus, it was not specific for a mycohost. P. grisea seems to evolve in the direction of having a broad mycohost range. Seventeen isolates of Verticillium-like fungi were isolated from rust sori. Based on morphological data and DNA sequence analysis, the isolates were identified as three Lecanicillium species, viz. L. attenuatum, Lecanicillium sp. 1, Lecanicillium sp. 2, and V. epiphytum. The unidenified two species of Lecanicillium appear to be previously unknown taxa. Sixty-six isolates of miscellaneous hyphomycetes belonging to 6 species of 5 genera were obtained from pustules of rust fungi. On the basis of morphological and molecular analyses, the miscellaneous hyphomycetes growing on rusts were identified as Acrodontium crateriforme, Cladophialophora pucciniophila, Cladosporium cladosporioides, Phacellium vossianum, Ramularia coleosporii, and R. uredinicola.

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Color Tuning of a Mn4+ Doped Phosphor : Sr1-xBaxGe4O9:MnMn4+0.005 (0.00 ≤ x ≤ 1.00) (Mn4+ 도핑된 형광체, Sr1-xBaxGe4O9:MnMn4+0.005 (0.00 ≤ x ≤ 1.00)의 Color Tuning)

  • Park, Woon Bae
    • Journal of the Korean Chemical Society
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    • v.61 no.4
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    • pp.163-167
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    • 2017
  • Along with the progress of white LED technology, red phosphors have become increasingly important in industry and academia, and a more specific demand has steadily increased in the market. Red phosphors are used in high efficiency and high rendering LED lightings. However, using red phosphors with $Eu^{2+}$ activators caused color rewarming and reduced emission intensity in white LED chips due to strong reabsorption in the green or yellow wavelength range caused by the 4f-5d transition. $Mn^{4+}$ doped phosphors which have no such drawbacks and which can further improve the color rendering index (CRI) are now of great interest. However, $Mn^{4+}$-doped phosphors have a disadvantage in that the emission wavelength is determined depending on the host due to the $^2E_g{\rightarrow}^4A_2$ transition. In this study, the $SrO-BaO-GeO_2$ solid-solution was selected, and $Sr_{1-x}B_axGe_4O_9:Mn^{4+}{_{0.005}}$ ($0{\leq}x{\leq}1$) phosphors were synthesized and characterized. This led to a versatile color tuning in LED technology.

Ho3+-Doped Amorphous Dielectrics:Emission and Excitation Spectra of the 1.6 μm Fluorescence (Ho3+ 첨가 비정질 유전체 : 1.6μm 헝광의 방출 및 여기 스펙트럼)

  • 최용규
    • Journal of the Korean Ceramic Society
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    • v.41 no.8
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    • pp.618-622
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    • 2004
  • Excitation spectra of the 1.6 rm emission originating from $Ho^{3+}$$^{5}$ I$_{5}$ \longrightarrow$^{5}$ I$_{7}$ transition in fluoride, sulfide, and selenide glasses were measured at wavelengths around 900nm where the fluorescing $^{5}$ I$_{5}$ level is located. In specific energy range where the frequency upconversion populating $^{5}$ F$_{1}$ state happens, the excitation efficiency of the 1.6 fm emission was deteriorated in fluoride and sulfide hosts. In selenide however spectral line shapes of the excitation spectrum and the '$^{5}$ I$_{8}$ \longrightarrow$^{5}$ I$_{5}$ absorption spectrum looked seemingly identical to each other. Differences in optical nonlinearity as well as electronic band gap energy of the host glasses used are responsible for the experimental observations. On the other hand, codoping of rare earths such as Tb$^{3+}$, Dy$^{3+}$, Eu$^{3+}$, and Nd$^{3+}$ was effective in decreasint the terminating $^{5}$ I$_{7}$ level lifetime. However, at the same time, some of the codopants increased unnecessary absorption at the 1.6 $\mu$m wavelengths via their ground state absorption. Though the lifetime quenching effect of Eu$^{3+}$ was moderate, it exhibited no additional extrinsic absorption at the 1.6 $\mu$m band.EX>m band.

Luminescence Characteristics of Mg2+·Ba2+ Co-Doped Sr2SiO4:Eu Yellow Phosphor for Light Emitting Diodes (LED용Mg2+·Ba2+Co-Doped Sr2SiO4:Eu 노란색 형광체의 발광특성)

  • Choi, Kyoung-Jae;Jee, Soon-Duk;Kim, Chang-Hae;Lee, Sang-Hyuk;Kim, Ho-Kun
    • Journal of the Korean Ceramic Society
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    • v.44 no.3 s.298
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    • pp.147-151
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    • 2007
  • An improvement for the efficiency of the $Sr_{2}SiO_{4}:Eu$ yellow phosphor under the $450{\sim}470\;nm$ excitation range have been achieved by adding the co-doping element ($Mg^{2+}\;and\;Ba^{2+}$) in the host. White LEDs were fabricated through an integration of an blue (InGaN) chip (${\lambda}_{cm}=450\;nm$) and a blend of two phosphors ($Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor) in a single package. The InGaN-based two phosphor blends ($Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor) LEDs showed three bands at 450 nm, 550 nm and 640 nm, respectively. The 450 nm emission band was due to a radiative recombination from an InGaN active layer. This 450 nm emission was used as an optical transition of the $Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor. As a consequence of a preparation of white LEDs using the $Mg^{2+},\;Ba^{2+}\;co-doped\;Sr_{2}SiO_{4}:Eu$ yellow phosphor+CaS:Eu red phosphor yellow phosphor and CaS:Eu red phosphor, the highest luminescence efficiency was obtained at the 0.03 mol $Ba^{2+}$ concentration. At this time, the white LEDs showed the CCT (5300 K), CRI (89.9) and luminous efficacy (17.34 lm/W).

Genetic Environment of the Samsung Gold-Silver Deposit, Republic of Korea: Ore Minerals, Fluid Inclusion and Stable Isotope Studies (삼성 금-은광상의 생성환경: 광석광물, 유체포유물 및 안정동위원소 연구)

  • Yoo, Bong-Chul;Lee, Gill-Jae;Koh, Sang-Mo;You, Byoung-Woon
    • Economic and Environmental Geology
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    • v.43 no.5
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    • pp.443-453
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    • 2010
  • The Samsung gold-silver deposit consists of quartz veins that fill along the fault zone within Cretaceous shale and sandstone. Mineralization is occurred within fault-breccia zones and can be divided into two stages. Stage I is main ore mineralization and stage II is barren. Stage I is associated with wall-rock alteration minerals(sericite, pyrite, chlorite, quartz), rutile, base-metal sulfides(pyrrhotite, pyrite, sphalerite, chalcopyrite, galena), and electrum. Stage II occur quartz, calcite and pyrite. Fluid inclusion data indicate that homogenization temperatures and salinities of stage I range from 145 to $309^{\circ}C$ and from 0.4 to 12.4 wt.% NaCl, respectively. It suggests that hydrothermal fluids were cooled and diluted with the mixing of meteoric water. The main deposition of base-metal sulfides and electrum occurred as a result of cooling and dilution at temperature between $200^{\circ}C$ and $300^{\circ}C$. Sulfur(9.3~10.8‰) isotope composition indicates that ore sulfur was mainly derived from a magmatic source as well as the host rocks. The calculated oxygen[-2.3~0.9‰(quartz: 0.3‰, 0.9‰, calcite: -2.3‰)] and hydrogen[-86~-76‰(quartz: -86‰, -82‰, calcite: -76‰)] isotope compositions indicate that hydrothermal fluids may be meteoric origin with some degree of mixing of another meteoric water for paragenetic time.

Recombinant Mannose-binding Lectin Protein and Anti-Mannose-binding Lectin Polyclonal Antibody Production (재조합 mannose-binding lectin 단백질과 anti-mannose-binding lectin polyclonal 항체 제작)

  • Kwon, Hyun-Mi;Park, Jung-Ae;Choi, Byung-Tae;Choi, Yung-Hyun;Chung, Kyung-Tae
    • Journal of Life Science
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    • v.19 no.2
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    • pp.284-288
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    • 2009
  • The innate immune system is important for the first line of host defence against infectious agents, which have penetrated the mechanical barriers. Mannose-binding lectin (MBL or mannan-binding protein, MBP) is a serum protein that is synthesized in the liver as a part of the acute phase response. MBL binds to carbohydrate structures presented by a wide range of pathogenic bacteria, viruses, fungi, and parasites. MBL is synthesized as a monomer that has a carboxy-terminal carbohydrate recognition domain, a neck region and a collagen region. Low MBL level was reported to be the most frequent immuno-deficiency syndrome. Although extensive studies have yielded detailed information on the structure of MBL, functions of the MBL complex are not fully understood yet. We, here, present cloning process of MBL cDNA from the rat liver and production of truncated recombinant MBL protein using a bacterial expression system in order to produce anti-MBL polyclonal antibody. Anti-MBL polyclonal antibody was raised in a New Zealand rabbit and its affinity was tested against recombinant protein using western blot technique. MBL cDNA, recombinant protein and anti-MBL antibody could be used as great arsenals to dissect cellular biochemistry of MBL.

Isolation and Identification of Antagonistic Bacterium Active against Sclerotinia sclerotioum Causing Sclerotinia Rot on Crisphead Lettuce (결구상추 균핵병균(Sclerotinia sclerotioum)에 대한 길항세균의 분리 및 동정)

  • Kim, Han-Woo;Lee, Kwang-Youll;Baek, Jung-Woo;Kim, Hyun-Ju;Park, Jong-Young;Lee, Jin-Woo;Jung, Soon-Je;Moon, Byung-Ju
    • Research in Plant Disease
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    • v.10 no.4
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    • pp.331-336
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    • 2004
  • The fungus genus Sclerotinia contains a number of important plant pathogens. Vegetable growers in our country are probably most familiar with Sclerotinia sclerotiorum, the causes of sclerotinia rot on crisphead lettuce. S. sclerotiorum has a wide host range which can include lettuce as well as crops such as broccoli, cabbage, carrots, celery, beans, peppers, potatoes, stocks, and tomato. Some fungicides, including benomyl, are effective in some crops, but not all. So, we isolated a antagonistic bacteria that are active on sclerotinia rot caused by S. sclerotiorum and that can be used to control it. About 702 strains had been isolated from soil around plant roots in the field. Ten strains showed strong antifungal activity against S. sclerotiorum. In pot test for antagonistic activity, A-7 strain showed high control value against the pathogen when compared with others. The strain was, therefore, selected as a biocontrol candidate against sclerotinia rot and its biochemical properties and 16S rDNA sequence was analyzed. The A-7 strain was highly related to Bacillus subtilis and B. amyloliquefaciens. To confirm precise identification, we had performed gyr A gene sequences analysis. Its sequence had 96% similarity with B. amyloliquefaciens. Consequently, the isolate was identified as B. amyloliquefaciens A-7.

Epidemiological Studies on Ascaris lumbricoides Reinfection in Rural Communities in Korea 1. The Relationship between Prevalence and Monthly Reinfection Rate (한국 농촌지역의 회충재감염에 대한 역학적 조사연구 I. 현재감염률과 월재감염률의 상관관계)

  • 채종일
    • Parasites, Hosts and Diseases
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    • v.21 no.2
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    • pp.135-141
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    • 1983
  • The epidemiological relationship between the current prevalence and monthly reinfection rate of Ascaris lumbricoides was observed in rural communities in Korea by means of blanket mass chemotherapy and worm collection for measurement of the prevalence and reinfection rates. During the period from 1975 to 1980, a total of 4,466 inhabitants in 10 different localities were treated with 10 mg/kg of pyrantel pamoate and 2 days' whole stools were collected from 2,547 inhabitants. The stools were examined for the presence of expelled adult and/or young worms, which represent the prevalence and reinfection rates for past 2 months respectively. After then, the obtained rates were correlated each other applying the timeprevalence curve proposed by Hayashi. It was observed that the prevalence (overall worm positive rate) and worm burden per individual ranged by areas from 13. 6 to 72. 3% and 1.4~10. 2 respectively. The calculated monthly reinfection rates (X) (from young worm positive rates) according to areas were in the range, 2.6~16.2%, and clearly correlated with the current prevalence (Y) under the equation, $Y=1-(l-X)^{7.2}$ where 7.2 is time in month. The equation means that after one time mass chemotherapy the period needed to attain equilibrium of prevalence again would be about 7~8 months. And it is inferred that the majority of reinfected worms in human host turn over every 7~8 months.

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