• Title/Summary/Keyword: Alkali metal

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Synthesis and characterization of ZnS:Mn,Cl phosphor by combustion method

  • Park, Jo-Yong;Han, Sang-Do;Myung, Kwang-Shik;Kim, Byung-Guen;Yang, Hua;O, Byung-Seung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.980-983
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    • 2003
  • The preparation of ZnS:Mn,Cl phosphor has been carried out by combustion method. Manganese nitrate was decomposed with an organic fuel at $500^{\circ}C$ to give fine sized crystallites in presence of alkali metal halides at a lower temperature than the conventional synthesis. The phosphors thus obtained were then heated at 900 to $1200^{\circ}C$ in an inert atmosphere, for 3hours to get better luminescent properties. The phosphors were prepared at different temperatures and at different doping concentrations of manganese to determine the optimal conditions for synthesizing the phosphors with superior optical properties. Scanning electron microscopy (SEM) investigations have been carried out to observe the particle morphology and the grain size. Powder X-ray diffraction(XRD) was also performed to characterize the phosphors.

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Esterification of the Soybean Oil and Waste Vegetable Oil by Solid Catalysts (고체 촉매를 이용한 대두유와 폐식용유의 에스테르화)

  • Sin, Yong Seop
    • Journal of Environmental Science International
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    • v.13 no.1
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    • pp.79-87
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    • 2004
  • Esterification of soybean oil with methanol was investigated. First of all, liquid-liquid equilibriums for systems of soybean oil and methanol were measured at temperatures ranging from 40 to 65$^{\circ}C$. Profiles of conversion of soybean oil with time were determined from the glycerine content in reaction mixtures for the different kinds of catalysts, such as NaOH, CaO, Ca(OH)$_2$, MgO, Mg(OH)$_2$, and Ba(OH)$_2$. The effects of dose of catalyst, cosolvent and reaction temperature on final conversion were examined. Esterification of waste vegetable oil with methanol was investigated and compared to the case of soybean oil. Solubility of methanol in soybean oil was substantially greater than that of soybean oil in methanol. When the esterification reaction of soybean oil was catalyzed by solid catalyst, final conversion was strongly dependent on the alkalinity of the solid catalyst, and increased with the alkalinity of the metal. Hydroxides from the alkali metals were more effective than oxides. When Ca(OH)$_2$ was used for the esterification catalyst, maximum value of final conversion was measured at dose of 4%. When CHCl$_3$ as a cosolvent, was added into the reaction mixture of soybean oil which catalyzed by Ba(OH)$_2$, maximum value of final conversion was appeared at dose of 3%. When waste vegetable oil was catalyzed by NaOH and solid catalysts, high final conversion, over 90%, and fast reaction rate were obtained.

UO22+ Ion-Selective Membrane Electrode Based on a Naphthol-Derivative Schiff's Base 2,2'-[1,2-Ethandiyl bis(nitriloethylidene)]bis(1-naphthalene)

  • Shamsipur, Mojtaba;Saeidi, Mahboubeh;Yari, Abdullah;Yaganeh-Faal, Ali;Mashhadizadeh, Mohammad Hossein;Azimi, Gholamhasan;Naeimi, Hossein;Sharghi, Hashem
    • Bulletin of the Korean Chemical Society
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    • v.25 no.5
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    • pp.629-633
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    • 2004
  • A new PVC membrane electrode for $UO_2^{2+}$ ion based on 2,2'-[1,2-ethanediyl bis (nitriloethylidene)]bis(1-naphthalene) as a suitable ionophore was prepared. The electrode exhibites a Nernstian response for $UO_2^{2+}$ ion over a wide concentration range ($1.0{\times}10^{-1}-1.0{\times}10^{-7}$M) with a slope of 28.5 ${\pm}$ 0.8 mV/decade. The limit of detection is $7.0{\times}10^{-8}$M. The electrode has a response time of < 20 s and a useful working pH range of 3-4. The proposed membrane sensor shows good discriminating abilities towards $UO_2^{2+}$ ion with regard to several alkali, alkaline earth transition and heavy metal ions. It was successfully used to the recovery of uranyl ion from, tap water and, as an indicator electrode, in potentiometric titration of $UO_2^{2+}$ ion with Piroxycam.

Enzymatic Properties of Serratia marcescens Pretense (Serratia marcescens Protease의 효소학적 특성)

  • 최병범
    • The Korean Journal of Food And Nutrition
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    • v.16 no.2
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    • pp.152-157
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    • 2003
  • Serratia marcescens ATCC 25419 protease was purified to homogeneity by ammonium sulfate treatment, and DEAE-cellulose anion exchange chromatography. The specific activity of the enzyme was increased 448-fold during purification with an overall yield of 43.0%. Metal reactivation on the purified protease from S. marcescens was studied. S. marcescens protease was a metalloenzyme to be completely inhibited its activity by EDTA and the enzyme outstandingly inhibited by Hg, Fe, Cu, but the activity was increased approximately 20% by Co. The reactivation of the apoenzyme was effective with Mn, Co, Zn in pH range from 6 to 8. Among metalloenzymes prepared to the addition of Mn, Co, Zn to restore the degree of activity of native enzyme, Zn-enzyme was similar to the native enzyme in respects with enzyme activity, alkali-inactivation, thermo-stability.

Effect of Al Alloy Composition on Physical and Crystallographical Properties of Plasma Electrolytic Oxidized Coatings II. Crystallographic Analysis of PEO Layer (플라즈마 전해 산화 코팅에 있어서 알루미늄 합금 모재 성분의 물리적, 결정학적 영향 II. PEO 층의 결정상 분석)

  • Kim, Bae-Yeon;Lee, Deuk-Yong;Shin, Min-Chul;Shin, Hyun-Gyoo;Kim, Byeong-Kon;Kim, Sung-Youp;Kim, Kwang-Youp
    • Journal of the Korean Ceramic Society
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    • v.47 no.4
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    • pp.283-289
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    • 2010
  • Physical properties of Plasma electrolytic oxidized 8 different kinds of Al alloys, A-1100, A-2024, A-5052, A-6061, A-6063, A-7075, ACD-7B and ACD-12 were investigated. The electrolyte for PEO was $Na_2SiO_3$ and NaOH and some alkali earthen metal salts system solution. $\eta$-alumina, as well as $\gamma$-alumina, was main crystal phase, which were ever reported. Also, $Al_{4.95}Si_{1.05}O_{9.52}$ was found only in this research. So we can conclude that the process conditions of PEO apparatus and composition and concentration of its electrolyte affects crystal structure and physical properties of PEO layers much more than the compositions of Al alloy.

La(III) Selective Membrane Sensor Based on a New N-N Schiff's Base

  • Ganjali, Mohammad Reza;Matloobi, Parisa;Ghorbani, Maryam;Norouzi, Parviz;Salavati-Niasari, Masoud
    • Bulletin of the Korean Chemical Society
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    • v.26 no.1
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    • pp.38-42
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    • 2005
  • Bis(2-methylbenzaldehyde)butane-2,3-dihydrazone(TDSB) was used as new N-N Schiff's base which plays the role of an excellent ion carrier in the construction of a La(III) membrane sensor. The best performance was obtained with a membrane containing, 30% poly(vinyl chloride), 60% benzyl acetate, 6% TDSB and 4% sodium tetraphenyl borate. This sensor reveals a very good selectivity towards La(III) ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The proposed electrode exhibits a Nernstian behavior (with slope of 19.8 mV per decade) over a wide concentration range (1.0 ${\times}$ 10$^{-5}$-1.0 ${\times}$ 10$^{-1}$ M). The detection limit of the sensor is 7.0 ${\times}$ 10$^{-6}$ M. It has a very short response time, in the whole concentration range ($\sim$5 s), and can be used for at least twelve weeks in the pH range of 3.0-9.4. The proposed sensor was successfully applied as an indicator electrode for the potentiometric titration of a La(III) solution, with EDTA. It was also successfully applied in the determination of fluoride ions in three mouth wash preparations.

The Potentiometric Performance of Mercury (II) Ion-Selective Electrode Based on Tetracycline Antibiotics

  • Baek, Jong-Gyu;Rhee Paeng, In-Sook
    • Journal of the Korean Electrochemical Society
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    • v.11 no.1
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    • pp.59-63
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    • 2008
  • Poly (vinylchloride) (PVC) membrane electrodes based on neutral carrier, tetracycline was prepared as an active sensor for Hg(II) ion, and tested in different contents of the potassium tetrakis (4-chlorophenyl) borate (KTpClPB) as lipophilic salt. Bis (2-ethylhexyl) sebacate (DOS), bis(l-butylpentyl) adipate (BBPA), 2-nitrophenyl octyl ether (NPOE) and dibutyl phthalate (DBP) were used as diverse plasticizing solvent mediators. This electrode shows excellent potentiometric response characteristics and display good linearity with log $[Hg^{+2}]$ versus EMF response, over a range of concentrations between $10^{-7}$ and $10^{-3}M$. With 30.8mV/decade Nernstian slope, the detection limit was $6.9{\times}10^{-9}M$ and the response time was less than 20s. The proposed electrode yields very good selectivity for mercury (II) ion over many cations such as alkali, alkaline earth, transition and heavy metal ions. And it shows a very stable potential values in a wide pH range. This reliable electrode prepared was kept at least a month without considerable alteration in their response to Hg (II) ion.

Characteristics of Hemolysin from Bacillus thuringiensis subsp. israelensis (Bacillus thuringiensis subsp. israelensis 균주의 Hemolysin 성질)

  • 황지연;김광현
    • Microbiology and Biotechnology Letters
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    • v.15 no.6
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    • pp.425-429
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    • 1987
  • The extra-cellular hemolysin from Bacillus thuringiensis subsp. israelensis was purified in the process of suiting with (NH$_4$)$_2$SO$_4$, Sephadex G-200 gel filtration, and DEAE-cellulose column chromatography. The purified hemolysin had molecular weight of approximately 47,000 dalton on SDS-polyacrylamide gel electrophoresis. The activity of purified hemolysin on human red blood cells was increased by thiol agents, but that was Inhibited by cholesterol, protease treatment, and metal salts such as CuSO$_4$, and FeSO$_4$, respectively.

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Removal of Cu and Fe Impurities on Silicon Wafers from Cleaning Solutions (세정액에 따른 실리콘 웨이퍼의 Cu 및 Fe 불순물 제거)

  • Kim, In-Jung;Bae, So-Ik
    • Korean Journal of Materials Research
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    • v.16 no.2
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    • pp.80-84
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    • 2006
  • The removal efficiency of Cu and Fe contaminants on the silicon wafer surface was examined to investigate the effect of cleaning solutions on the behavior of metallic impurities. Silicon wafers were intentionally contaminated with Cu and Fe solutions by spin coating and cleaned in different types of cleaning solutions based on $NH_4OH/H_2O_2/H_2O\;(SC1),\;H_2O_2/HCl/H_2O$ (SC2), and/or HCl/$H_2O$ (m-SC2) mixtures. The concentration of metallic contaminants on the silicon wafer surface before and after cleaning was analyzed by vapor phase decomposition/inductively coupled plasma-mass spectrometry (VPD/ICP-MS). Cu ions were effectively removed both in alkali (SC1) and in acid (SC2) based solutions. When $H_2O_2$ was not added to SC2 solution like m-SC2, the removal efficiency of Cu impurities was decreased drastically. The efficiency of Cu ions in SC1 was not changed by increasing cleaning temperature. Fe ions were soluble only in acid solution like SC2 or m-SC2 solution. The removal efficiencies of Fe ions in acid solutions were enhanced by increasing cleaning temperature. It is found that the behavior of metallic contaminants as Cu and Fe from silicon surfaces in cleaning solutions could be explained in terms of Pourbaix diagram.

Novel Copper(Ⅱ)-Selective Senor Based on a New Hexadentates Schiff's Base

  • Ganjali, Mohammad Reza;Emami, Mehdi;Salavati Niasari, Masoud
    • Bulletin of the Korean Chemical Society
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    • v.23 no.10
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    • pp.1394-1398
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    • 2002
  • A novel copper(II) membrane electrode based on diphenylisocyanate bis(acetylacetone) ethylenediimine (DIBAE), as a new hexadentates Schiff's base was prepared. The electrode exhibited a Nernstian response for Cu$^{2+}$ ions over a wide concentration range (1.0 ${\times}$ 10$^{-1}$ to 1.0 ${\times}$ l0$^{-6}$ M) with a limit of detection of 6.0 ${\times}$ 10$^{-7}$ M (39 ppb). The sensor shows a fast response time (15s) and the membrane can be used for more than 4 months without observing any major deviation. The electrode revealed very good selectivity with respect to many cations including alkali, alkaline earth, transition and heavy metal ions. The proposed sensor could be used in a pH range of 3.0-7.5. It was applied to the direct potentiometric determination of copper in black tea, and in wastewater of copper electroplating samples. The electrode was also used in potentiometric titration of the copper(II) ion with EDTA.