• Title/Summary/Keyword: chelating agent

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Polymerization of Methyl Methacrylate Initiated by Cobalt (II) Nitrate (질산코발트 (II)에 의한 Methyl Methacrylate의 중합)

  • Jang-oo Lee;Dong-ho Lee;Tae-oan Ahn
    • Journal of the Korean Chemical Society
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    • v.19 no.6
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    • pp.463-467
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    • 1975
  • The polymerization of methyl methacrylate(MMA) initiated by cobalt (II) nitrate in tetrahydrofuran (THF) has been studied. From the results of kinetic studies, the overall polymerization rate (Rp) could be expressed as following; $R_p=k\;[cobalt(Ⅱ)\;nitrate]^{0.5}\;[MMA]^{1.5}$ By considering the effects of chelating agent on the polymerization rate, it could be assumed that the monomer, MMA might form a coordination complex with cobalt(II) nitrate. In the presence of radical inhibitor hydroquinone, the inhibition time was observed. And the apparent overall activation energy was calculated to be 14.0 kcal/mole.

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Copper Uptake by Tyromyces palustris (Tyromyces palustris를 이용한 구리의 제거)

  • Son, Dong-Weon;Lee, Dong-Heub;Kang, Chang-Ho
    • Journal of the Korean Wood Science and Technology
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    • v.26 no.1
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    • pp.57-62
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    • 1998
  • In this research, the removal or uptake of heavy metals such as coppers by using oxalic acid metabolism of wood rot fungi, Tyromyces palustris were endeavored. As results, the addition of oxalic acid to copper containing culture did not cause the mycelium growth, but Tyromyces palustris was able to grow in this culture without inhibition. Tyromyces palustris grew with the cicular halo type in copper containing culture, and this type was formed as collectives after examining by microscope, and considered as copper oxalates by analyzing FT-IR comparison experiment with standards. According to this result, Tyromyces palustris has secreted oxalic acid during incubation, this secreted oxalic acid was combined with coppers, and formed copper oxalates by chelating reactions. In other words, the oxalic acid was might be as non-toxifying agent of coppers in medium. By using this copper removal mechanisms, Tyromyces palustris immobilized sawdust was used in bench scale air lift system for removing coppers. The added coppers were almost removed from the system within 72hrs. Therefore, this nonenzymatic wood degradation mechanism may give a possibility for removing coppers from copper containing waste water.

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Synthesis and Characterization of Cathode Materials for the Lithium Secondary Batteries by Spray Drying Method

  • Oh, Si-Hyoung;Jeong, Woon-Tae;Cho, Won-Il;Cho, Byung-Won
    • Journal of the Korean Electrochemical Society
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    • v.8 no.1
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    • pp.42-46
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    • 2005
  • It has been known that the synthesis of the cathode materials for the lithium rechargeable batteries by the sol-gel process has many advantages over the conventional solid-state method. It has been, however, a continuing issue that new additional steps should be introduced to commercialize this process. In this work, spray drying was introduced to the existing sol-gel process as a continuous mass production method of the pre-heat treatment precursor materials. The precursors of $LiCoO_2$ and $LiNi_{0.8}Co_{0.2}O_2$ were continuously produced through spray drying from the solution containing stoichiometric amount of lithium, cobalt, and nickel sources as well as a chelating agent. The process variables, such as pH of the starting solution, spray drying conditions, and calcination conditions were optimized. The XRD pattern for the synthesized material indicated a good crystallinity with a layered structure.

Effects of DTPA on Microelements in Soybean and Bush Bean (대두 및 강낭콩내 미량원소의 농도 및 분포에 미치는 DTPA의 영향)

  • 차종환
    • Journal of Plant Biology
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    • v.16 no.3_4
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    • pp.40-44
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    • 1973
  • Hawkeye(Fe-chlorosis resistant) and PI 54619-5-1(Fe-chlorosis sensitive) soybeans were grown with and without DPTA(diethylene triamine pentaacetic acid) in Yolo loam soil. The major purpose of the study was to compare leaf-stem distribution of microelements for different treatments which increase concentrations of microelements in plants to evaluate the role of the chelating agent in increasing translocation of the microelements. Plant responses and yields were recorded and Fe, Mn, Zn, Cu, Al, Co, N, Sn, Pb and Mo contents of leaves and stems were determined by emission spectrography. Sulfur(soil pH4) increased leaf concentrations of Mn, Zn, Cu, CO, Ni, Sn and Pb. DTPA, particularly at 50ppm in soil, increased leaf concentrations of Fe, Mn, Zn, Cu, Co, Ni and Mo. It increased Ti in leaves for the PI 54619-5-1 soybeans only. DTPA increased the ratios of the concentration in leaves to that in stems for Fe, Zn, Cu, Al, Ti, CO, Ni and Mo. Sulfur which increased the microelement concentration in both leaves and stems did not have this effect. DTPA increased the ratio at soil pH 6 and 8.5 in leaves to that in stems of the bush bean plants for Fe, Zn, Cu, Ni, but to a lesser extent in bush beans than in soybeans. PI 54619-5-1 soybeans tended to contain less of most of the metals than did Hawkeye soybeans.

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Fabrication of Thin Film Dielectric by Hybrid Sol (Hybrid Sol을 이용한 박막 유전체 제작)

  • Kim, Yong-Suk;Yoo, Won-Hee;Chang, Byeung-Gyu;Oh, Yong-Soo
    • Korean Journal of Materials Research
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    • v.17 no.4
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    • pp.185-191
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    • 2007
  • The purpose of this study is to evaluate the thin fihn dielectric made of hybrid sol, which consist of barium titanate powder, polymeric sol and other polymers. This sol will be used dielectric applied to small, thin electric passive components such as MLCC(Multi Layer Ceramic Condenser), resister, inductor. This sol is composed of mixed fine barium titanate powder and polymeric sol including Ba, Ti-precursor, solvent, chelating agent, chemical reaction catalyst, the additive sols to improve fired densification and temperature reliability. First at all, we mixed hybrid sol to be dispersed and be stabilized by ball milling for 24hrs. By spin coating method, we makes thin film dielectric on the convectional green sheet for MLCC. After heat treatments, we analyzes the structure morphology, physical, electrical properties and X5R Temperature properties.

Role of Calcium Influx in mediating the TRH-induced c-fos Gene Expression (갑상선자극 분비 호르몬에 의해 유도되는 c-fos 유전자 발현에서 Ca2+의 역할에 관한 연구)

  • Seung Kirl Ahn;Don
    • The Korean Journal of Zoology
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    • v.36 no.4
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    • pp.487-495
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    • 1993
  • TRH (Thvrotropin-Releasing Hormone) known to regulate the transcription of the TSH (Thyroid-Stimulating Hormones gene in pituitary cells, but little is understood about the mechanism(sl involved. re present study was attempted to elucidate the role of Ca2+ movement through the voltage-gated channels in the regulation of TSH gene transcription. The c-fos is one of immediate early genes and used as model system for the investigation of signaling pathwavs involved in various stimuli. The changes of c-fos mRNA levels were determined after treatment of various agents using Northern and slot hybridization analysis. The c-fos mRNA was rapidly and transiently induced by TRH (about 3-fold) in GH3 cells and this induction was repressed by calcium chelating agent (EGTA), calcium channel blocker (verapamil) anti protein kinase C inhibitor (aminoacridine). The abilities of forskolin (adenvlate cvclase activators, PMA (protein kinase C activator), and A23187 (calcium ionophore) to affect c-ios gene transcription, either alone or in combination with TRH were tested in the same cells. All of them significantly increased the level of c-fos mRUA. However, no additive relationship was observed in all combined treatments except forskolin. These results suggest that TRH action on the c-fos gene activation is mediated by calcium influx as well as through protein kinase C.

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Photoinduced Superhydrophilicity in TiO2 Thin Films Modified with WO3

  • Hwang, Young-Kyu;Patil, Kashinath Rangu;Kim, Hye-Kyung;Dattatraya Sathaye, Shivaram;Hwang, Jin-Soo;Park, Sang-Eon;Chang, Jong-San
    • Bulletin of the Korean Chemical Society
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    • v.26 no.10
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    • pp.1515-1519
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    • 2005
  • Tungsten oxide-modified TiO2 thin films were formed on a glass substrate by sol-gel and dip coating processes using acetyl acetone as a chelating agent. The hydrophilic properties of the thin films were investigated with illumination of UV light. The dependence of water contact angle on material composition and morphology of the film is established with SEM image and AFM profile. The surface morphology was controlled with the change of precursor concentration. 0.01 M of tungsten oxide-modified Ti$O_2$ have shown the highest hydrophilicity after UV-irradiation. The effect of composition on photoinduced hydrophilicity of the W$O_3$-Ti$O_2$ films was also investigated. The films were characterized by XRD, SEM, AFM and XPS.

Antimicrobial Peptides from Lactobacillus plantarum UTNGt2 Prevent Harmful Bacteria Growth on Fresh Tomatoes

  • Tenea, Gabriela N.;Pozo, Tatiana Delgado
    • Journal of Microbiology and Biotechnology
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    • v.29 no.10
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    • pp.1553-1560
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    • 2019
  • In a previous study, the antimicrobial peptides extracted from Lactobacillus plantarum UTNGt2 of wild-type fruits of Theobroma grandiflorum (Amazon) were characterized. This study aimed to investigate the antimicrobial mechanisms of peptides in vitro and its protective effect on fresh tomatoes. The addition of partially purified Gt2 peptides to the E. coli suspension cells at the exponential ($OD_{605}=0.7$) growth phase resulted in a decrease with 1.67 (log10) order of magnitude compared to the control without peptide. A marginal event (< 1 log10 difference) was recorded against Salmonella, while no effect was observed when combined with EDTA, suggesting that the presence of a chelating agent interfered with the antimicrobial activity. The Gt2 peptides disrupted the membrane of E. coli, causing the release of ${\beta}$-galactosidase and leakage of DNA/RNA molecules followed by cell death, revealing a bacteriolytic mode of action. The tomatoes fruits coated with Gt2 peptides showed growth inhibition of the artificially inoculated Salmonella cocktail, demonstrating their preservative potential.

Antagonistic and Plant Growth-Promoting Effects of Bacillus velezensis BS1 Isolated from Rhizosphere Soil in a Pepper Field

  • Shin, Jong-Hwan;Park, Byung-Seoung;Kim, Hee-Yeong;Lee, Kwang-Ho;Kim, Kyoung Su
    • The Plant Pathology Journal
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    • v.37 no.3
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    • pp.307-314
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    • 2021
  • Pepper (Capsicum annuum L.) is an important agricultural crop worldwide. Recently, Colletotrichum scovillei, a member of the C. acutatum species complex, was reported to be the dominant pathogen causing pepper anthracnose disease in South Korea. In the present study, we isolated bacterial strains from rhizosphere soil in a pepper field in Gangwon Province, Korea, and assessed their antifungal ability against C. scovillei strain KC05. Among these strains, a strain named BS1 significantly inhibited mycelial growth, appressorium formation, and disease development of C. scovillei. By combined sequence analysis using 16S rRNA and partial gyrA sequences, strain BS1 was identified as Bacillus velezensis, a member of the B. subtilis species complex. BS1 produced hydrolytic enzymes (cellulase and protease) and iron-chelating siderophores. It also promoted chili pepper (cv. Nockwang) seedling growth compared with untreated plants. The study concluded that B. velezensis BS1 has good potential as a biocontrol agent of anthracnose disease in chili pepper caused by C. scovillei.

Effect of nano size $Y_2O_3$ addition on the superconducting properties and microstructure of YBCO thin film prepared by TFA-MOD method. (TFA-MOD 방법에 의한 YBCO 박막제조에서 nano size $Y_2O_3$ 첨가효과)

  • Park Jin-A;Kim Byung-Joo;Hong Gye-Won;Lee Hee-Gyoun;Yoo Jai-Moo;Kim Young-Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.8 no.3
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    • pp.13-17
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    • 2006
  • The effect of the addition of the nano size $Y_2O_3$ powder on the microstructurte and superconducting properties of YBCO thin film deposited on LAO single crystalline substrate by TFA-MOD method was studied. Nano size $Y_2O_3$ powder was added to the stoichiometric precursor solution with a cation ratio of Y : Ba . Cu = 1 : 2 : 3 prepared using TFA as chelating agent. Precursor solutions with and without $Y_2O_3$ addition were coated on $LaAlO_3(100)$ single crystalline substrates by dip coating method. Calcination and conversion heat treatments were performed in controlled atmosphere containing moisture Current carrying capacity(Jc) of YBCO film was enhanced about 50% by $Y_2O_3$ doping and it is thought to be due to the better connectivity of YBCO grains and/or the flux pinning by the $Y_2O_3$ particles embedded in YBCO grains.