• Title/Summary/Keyword: Ion oxide

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Problem Analysis and Improvement of an Experiment on Reactivityof Metals in ChemistryⅠ (화학Ⅰ 금속의 반응성 실험의 문제점 분석 및 개선방안)

  • Seong, Suk-kyoung;Choi, Chui-Im;Jeong, Dae-Hong
    • Journal of the Korean Chemical Society
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    • v.53 no.3
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    • pp.368-376
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    • 2009
  • In this study we investigated and tried to understand problems monitored in an experiment on reactivity of metals in chemistry I. Three problems were discussed. First, the reason that aluminium plate does not react with other metal ions such as zinc, iron and copper was studied and the way to overcome this problem was suggested. Second, the reason that the bubbles were generated when FeS$O_4$(aq) and Zn(s) react was discussed. Third, the precipitates which appeared in the reaction of FeS$O_4$(aq) and Zn(s) were identified. Through reference study and experimental investigation, we could reach the following results. First, aluminium could not react with other metal ions due to the surface oxide layer that is formed very fast and prevents aluminium from reacting with metal ions in solution. This problem could be overcome by allowing a competing reaction of acid and aluminium during the reaction of aluminium and metal ions. Second, the observed bubbles were identified to be hydrogen gas, produced by the reaction between metals and hydronium ion in the solution. Third, black precipitates that were produced on the surface of zinc plate and exhibited magnetic property were characterized to be $Fe_3O_4$(s), and brown precipitates that were produced in the solution phase were to be $Fe_2O_3$(s) by the analysis of X-ray photoelectron spectra.

The Crystal Structure of an Iondine Sorption Complex of Dehydrated Calcium and Silver Exchanged Zeolite A ($Ag^+$이온과 $Ca^{2+}$이온으로 치환한 제올라이트 A를 탈수한 후 요오드를 흡착한 결정구조)

  • Bae, Myung-Nam;Kim, Yang;Kim, Un-Sik
    • Korean Journal of Crystallography
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    • v.6 no.2
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    • pp.118-124
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    • 1995
  • The crystal structure of an iodine sorption complex of vacumm-dehydrated Ag+ and Ca2+ exchanged zeolite A(a=12.174(3)Å) has been determined at 21℃ by single-crystal X-ray diffraction techniques in the cubic space group Pm3m. The crystal was prepared by flow method for three days using exchange solution in solution in which mole ratio of AgNO3 and Ca(NO3)2 was 1:150 with total concentration of 0.05 M. The complex was prepared by dehydration at 360℃ and 2×10-6 Torr for 2 days, followed by exposure to about 14.3 Torr of iodine vaporat 80℃ for 24 hours. Full-matrix least-squares refinement converged to the final error indices of R1=0.082, R2=0.068 using 122 reflections for which I > 3σ(I). Two Ag+ ions, 1.1 Ag+ ions, and 4.45 Ca2+ ions per unit cell are located on three different three-fold axes associated with 6-ring oxygens. Two Ag+ ions per unit cell are in the large cavity, 1.399(4)Å from the (111) plane of three oxygens. Another 1.1 Ag+ ions are found at opposite sites. Six iodine molecules are sorbed per unit cell. Each I2 molecule approaches a framework oxide ion axially (O-I=3.43(2)Å, I-I=2.92Å, I-I-O;166.1(3)°), by a charge transfer complex interaction. Two Ag+ ions make a close approach to the iodine molecules (Ag-I ; 2.73(2)Å).

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Olefin Separation Membranes Based on PEO/PDMS-g-POEM Blends Containing AgBF4/Al(NO3)3 Mixed Salts (AgBF4/Al(NO3)3 혼합염이 포함된 PEO/PDMS-g-POEM 블렌드 기반의 올레핀 분리막)

  • Kim, Sang Jin;Jung, Jung Pyu;Park, Cheol Hun;Kim, Jong Hak
    • Membrane Journal
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    • v.25 no.6
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    • pp.496-502
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    • 2015
  • Facilitated transport is one of the possible solutions to simultaneously improve permeability and selectivity, which is challenging in conventional polymer-based membranes. Olefin/paraffin separation using facilitated transport membrane has received much attention as an alternative solution to the conventional distillation process. Herein, we report olefin separation composite membranes based on the polymer blends containing $AgBF_4/Al(NO_3)_3$ mixed salts. Free radical polymerization process was used to synthesize an amphiphilic graft copolymer of poly(dimethyl siloxane)-graft- poly(ethylene glycol) methyl ether methacrylate (PDMS-g-POEM). In addition, poly(ethylene oxide) (PEO) was introduced to the PDMS-g-POEM graft copolymer to form polymer blends with various ratios. The propylene/propane mixed-gas selectivity and permeance reached up to 5.6 and 10.05 GPU, respectively, when the PEO loading was 70 wt% in polymer blend. The improvement of olefin separation performance was attributed to the olefin facilitating silver ions as well as the highly permeable blend matrix. The stabilization of silver ions in the composite membrane was achieved through the introduction of $Al(NO_3)_3$ which suppressed the reduction of silver ions to silver particles.

Thickness Determination of Ultrathin Gate Oxide Grown by Wet Oxidation

  • 장효식;황현상;이확주;조현모;김현경;문대원
    • Proceedings of the Korean Vacuum Society Conference
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    • 2000.02a
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    • pp.107-107
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    • 2000
  • 최근 반도체 소자의 고집적화 및 대용량화의 경향에 다라 MOSFET 소자 제작에 이동되는 게이트 산화막의 두께가 수 nm 정도까지 점점 얇아지는 추세이고 Giga-DRAM급 차세대 UNSI소자를 제작하기 위해 5nm이하의 게이트 절연막이 요구된다. 이런 절연막의 두께감소는 게이트 정전용량을 증가시켜 트랜지스터의 속도를 빠르게 하며, 동시에 저전압동작을 가능하게 하기 때문에 게이트 산화막의 두께는 MOS공정세대가 진행되어감에 따라 계속 감소할 것이다. 따라서 절연막 두께는 소자의 동작 특성을 결정하는 중요한 요소이므로 이에 대한 정확한 평가 방법의 확보는 공정 control 측면에서 필수적이다. 그러나, 절연막의 두께가 작아지면서 게이트 산화막과 crystalline siliconrksm이 계면효과가 박막의 두께에 심각한 영향을 주기 때문에 정확한 두께 계측이 어렵고 계측방법에 따라서 두께 계측의 차이가 난다. 따라서 차세대 반도체 소자의 개발 및 양산 체계를 확립하기 위해서는 산화막의 두께가 10nm보다 작은 1nm-5nm 수준의 박막 시료에 대한 두께 계측 방법이 확립이 되어야 한다. 따라서, 본 연구에서는 습식 산화 공정으로 제작된 3nm-7nm 의 게이트 절연막을 현재까지 알려진 다양한 두께 평가방법을 비교 연구하였다. 절연막을 MEIS (Medim Energy Ion Scattering), 0.015nm의 고감도를 가지는 SE (Spectroscopic Ellipsometry), XPS, 고분해능 전자현미경 (TEM)을 이용하여 측정 비교하였다. 또한 polysilicon gate를 가지는 MOS capacitor를 제작하여 소자의 Capacitance-Voltage 및 Current-Voltage를 측정하여 절연막 두께를 계산하여 가장 좋은 두께 계측 방법을 찾고자 한다.다. 마이크로스트립 링 공진기는 링의 원주길이가 전자기파 파장길이의 정수배가 되면 공진이 일어나는 구조이다. Fused quartz를 기판으로 하여 증착압력을 변수로 하여 TiO2 박막을 증착하였다. 그리고 그 위에 은 (silver)을 사용하여 링 패턴을 형성하였다. 이와 같이 공진기를 제작하여 network analyzer (HP 8510C)로 마이크로파 대역에서의 공진특서을 측정하였다. 공진특성으로부터 전체 품질계수와 유효유전율, 그리고 TiO2 박막의 품질계수를 얻어내었다. 측정결과 rutile에서 anatase로 박막의 상이 변할수록 유전율은 감소하고 유전손실은 증가하는 결과를 나타내었다.의 성장률이 둔화됨을 볼 수 있다. 또한 Silane 가스량이 적어지는 영역에서는 가스량의 감소에 의해 성장속도가 둔화됨을 볼 수 있다. 또한 Silane 가스량이 적어지는 영역에서는 가스량의 감소에 의해 성장속도가 줄어들어 성장률이 Silane가스량에 의해 지배됨을 볼 수 있다. UV-VIS spectrophotometer에 의한 비정질 SiC 박막의 투과도와 파장과의 관계에 있어 유리를 기판으로 사용했으므로 유리의투과도를 감안했으며, 유리에 대한 상대적인 비율 관계로 투과도를 나타냈었다. 또한 비저질 SiC 박막의 흡수계수는 Ellipsometry에 의해 측정된 Δ과 Ψ값을 이용하여 시뮬레이션한 결과로 비정질 SiC 박막의 두께를 이용하여 구하였다. 또한 Tauc Plot을 통해 박막의 optical band gap을 2.6~3.7eV로 조절할 수 있었다. 20$0^{\circ}C$이상으로 증가시켜도 광투과율은 큰 변화를 나타내지 않았다.부터 전분-지질복합제의 형성 촉진이 시사되었다.이것으로 인하여 호화억제에 의한 노화 방지효과가 기대되었지만 실제로 빵의 노화는 현저히 진행되었다

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A Study on the Recovery of a Metalic Fe-particle from the Steelmaking E.A.F. Slag by the Magnetic Separation (전기로 제강 슬래그에서 자력선별에 의한 지금의 회수)

  • 현종영;김형석;신강호;조동성
    • Resources Recycling
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    • v.6 no.3
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    • pp.3-8
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    • 1997
  • The EA.F. sleelmaking slag (slag that follow) of a cnmvany 1 Co.. containzd a simple substance of a metal, wustlte (FeO), magnetite (Fe,O,), gehlenite (CaAl,SiO,), monlicellite (CaMgSiO,), dc. To recovere a metal (Fe grade . t95%) in the slag, it is desirable that the particles of a metal are isolated from thc slag and madc for a liberated subslance. Then, the liberaled melal is easlly recoveled by a magnetic separation. If thc rcclarnalcd slag, the sizc of which ranges under 40 nun, have a mulli-stage crushing, the most of a metal in thc slag is simply isolaled as a liberated subslance. If the mad, lhat is a liberated subslance and a sphere, is recovered by a magnetic field intensity. the minimum intensity, at which a metal is attracted, is approximately IOOG and did no1 dcpcnd on the particle size of a metad in the same particles. TIe recovered material. that contdined a iron (Fe) over 95% is a metal which is crushed slag by l00G in the multi-stage. If the magnetic field intcns~ty increase, the recovery mcrcasc, but the concentration grade decrease Bewusc thc concentration eams more and more impurities, iron oxide and the coml~ound of alkali earth element. 'll~ercforc If the rccla~nated slag have the multi-stage crushing, the metal is almostly recovered in the crushed slag by lO0G on each particles. If the slag, used as a rcclamatian lhat is a amount of 350,000 tan from I Co., was undcr the multistage crushing and then separaled by 100gauss, it is possible to recova a metal approximately 2.500 Ion, lhat is 0.73% of n ~eclamated slag. in 304.7 mm particles and to recover 4.200 tan in 0.3-1.7 mm particles , that is 1.2% nf a rcclamated slag, in a year. Therefore, ihe told recoverable meld is 6,700 ton, that is 19% of a reclmated slag, in a year, too.

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A Classical Molecular Dynamics Study of the Mg2+ Coordination in Todorokite (토도로카이트 내 Mg2+ 배위구조에 대한 고전분자동력학 연구)

  • Kim, Juhyeok;Lee, Jin-Yong;Kwon, Kideok D.
    • Journal of the Mineralogical Society of Korea
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    • v.32 no.3
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    • pp.151-162
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    • 2019
  • Todorokite, a tunnel-structured manganese oxide, can contain cations within the relatively large nanopores created by the $3{\times}3$ Mn octahedra. Because todorokite is poorly crystalline and found as aggregates mixed with other phases of Mn oxides in nature, the coordination structure of cations in the nanopores is challenging to fully characterize in experiment. In the current article, we report the atomistic coordination structures of $Mg^{2+}$ ions in todorokite tunnel nanopores using the classical molecular dynamics (MD) simulations. In experiment, $Mg^{2+}$ is known to occupy the center of the nanopores. In our MD simulations, 60 % of $Mg^{2+}$ ions were located at the center of the nanopores; 40 % of the ions were found at the corners. All $Mg^{2+}$ located at the center formed the six-fold coordination with water molecules, just as the ion in bulk aqueous solution. $Mg^{2+}$ ions at the corners also formed the six-fold coordination with not only water molecules but also Mn octahedral surface oxygens. The mean squared displacements were calculated to examine the dynamic features of $Mg^{2+}$ ions in the one-dimensional (1D) nanopores. Our MD simulations indicate that the dynamic features of water molecules and the cations observed in bulk aqueous solution are lost in the 1D nanopores of todorokite.

In vitro correlation between anti-inflammatory and anti-oxidant effects of stone and seed of peaches cultivars (복숭아 품종별 핵과 종자의 항염증 및 항산화 효과간의 상관관계)

  • Jung, Kyung-Mi;Bae, Seung-hwa
    • Food Science and Preservation
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    • v.25 no.1
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    • pp.90-97
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    • 2018
  • Peach seeds contain a large amount of phenolic components and exhibit excellent physiological effects in various diseases. We examined the antioxidant effects of stone and seed of three peach cultivars (Miwhang, MH; Kanoiwa hakuto, KH; and Cheonhong, CH) by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, ferric reducing activity of plasma (FRAP) assay, and cupric ion reducing antioxidant capacity (CUPRAC) reduction. The results showed that the stone extracts of CH had higher levels of total phenols and flavonoids than those of the other cultivars do, and the stone extracts of KH and CH have the potential to reduce DPPH, FRAP, and CUPRAC activities. In addition, we found that KH, MH, and CH stone extracts decreased nitric oxide generation in RAW 264.7 and BV2 cells. The total phenol and flavonoid contents had no significant correlation with anti-oxidant activities. On the other hand, the anti-inflammatory activity had a low linear correlation with anti-oxidant activities and total phenol and flavonoid contents. The present results suggest that the correlation between antioxidant and anti-inflammatory effects of stone and seed, and the appropriate combination of the stone and seed extracts could be used as an anti-inflammatory treatment and prevention material, respectively.

Antioxidant, anti-cholinesterase, and inflammation inhibitory activities of fruiting bodies of Phallus impudicus var. impudicus L. (말뚝버섯 자실체의 항산화, 항콜린에스테라제 및 염증 저해 활성)

  • Yoon, Ki Nam;Lee, Tae Soo
    • Journal of Mushroom
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    • v.17 no.3
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    • pp.152-161
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    • 2019
  • Phallus impudicus var. impudicus L. is an edible mushroom that has long been used as folk medicine in China. The aim of this study was to evaluate the antioxidant, anti-cholinesterase, and inflammation inhibitory activities of a methanol extract of fruiting bodies of P. impudicus var. impudicus L. The extract exhibited good 1,1-diphenyl-2-picrylhydrazyl scavenging activity, excellent ferrous ion chelating activity, and moderate hydroxyl radical scavenging activity compared with BHT at 2.0 mg/ml. However, the reducing power of the extract was significantly lower than that the BHT positive control. Although the inhibitory activities of methanol extract on acetylcholinesterase and butyryl cholinesterase were significantly lower than the galanthamine positive control at the concentration tested, the inhibition of acetylcholinesterase and butyryl cholinesterase was 52.83% and 55.17%, respectively, at 1.0 mg/ml. The methanol extract also demonstrated excellent inhibition of inflammation-related activities, such as production of nitric oxide in lipopolysaccharide-induced RAW 264.7 macrophage cells and acute edema induced by administration of carrageenan on the hind paw of rats. The collective results suggest that the fruiting body of P. impudicus var. impudicus L. might be a good source of antioxidant, anti-cholinesterase, and anti-inflammation compounds.

Two Crystal Structures of Dehydrated Ag$^+$ and K$^+$Exchanged Zeolite A, $Ag_{12-x}K_x$-A, x = 1.3 and 2.7

  • Kim, Yang;Song, Seong-Hwan;Park, Jong-Yul;Kim, Un-Sik
    • Bulletin of the Korean Chemical Society
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    • v.9 no.6
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    • pp.338-341
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    • 1988
  • Two crystal structures of fully dehydrated silver and potassium exchanged zeolite A, stoichiometries of $Ag_{9.3}K_{{2.7}^-}A$ (${\alpha}$ = 12.282(2) ${\AA}$) and $Ag_{10.7}K_{{1.3}^-}{\AA}$ (${\alpha}$ = 12.287(2) A) per unit cell, have been determined from 3-dimensional x-ray diffraction data gathered by counter methods. All structures were solved and refined in the cubic space group Pm3m at 21(1)$^{\circ}C$ . The crystals of $Ag_{9.3}K_{{2.7}^-}A$ and $Ag_{10.7}K_{{1.3}^-}A$ were prepared by flow method using exchange solutions in which mole ratios of $AgNO_3$ and $KNO_3$ were 1:10 and 1:5, respectively, with total concentration of 0.05M. The structures of the dehydrated $Ag_{9.3}K_{{2.7}^-}A$ and $Ag_{10.7}K_{{1.3}^-}A$ were refined to yield the final error indices $R_1$ = 0.037 and $R_2$ = 0.040 with 321 reflections, and $R_1$ = 0.042 and $R_2$ = 0.043 with 371 reflections, repectively, for which I > 3${\sigma}$(I). In both structures, eight $Ag^+$ ions are found nearly at 6-ring centers and each $Ag^+$ ion is nearly in the (1 1 1) plane at its O(3) ligands. The 8-ring sites are preferentially occupied by $K^+$ ions in both structures. 1.3 and 1.7 reduced silver atoms per unit cell were found inside of sodalite units of $Ag_{9.3}K_{{2.7}^-}A$ and that of $Ag_{10.7}K_{{1.3}^-}A$, respectively. These reduced silver species were presumably formed from the reduction of $Ag^+$ ions by oxide ions of residual water molecule or of the zeolite framework. These two crystals may be presented as hexasilver cluster in 21.7% and 28.3% of sodalite unit cells for $Ag_{9.3}K_{{2.7}^-}A$ and $Ag_{10.7}K_{{1.3}^-}A$, repectively.

Antibacterial and Antiviral Activities of Multi-coating Polyester Textiles (다중 코팅 폴리에스터 섬유 여재의 항균 및 항바이러스 특성)

  • Ko, Sangwon;Lee, Jae-Young;Park, Duckshin
    • Applied Chemistry for Engineering
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    • v.33 no.4
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    • pp.444-450
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    • 2022
  • The effect of coated polyester (PET) textiles with metal oxide, chitosan, and copper ion on the antibacterial and antiviral activities was evaluated to investigate the applicability of multi-coated PET textiles as antiviral materials. Compared to coated PETs with a single agent, multi-coated PETs reduced the loading amount of coating materials as well as the contact time with bacteria for a bacterial cell number of < 10 CFU/mL, which was not detectable with the naked eyes. Metal oxides generate reactive oxygen species (ROS) such as free radicals by a catalytic reaction, and copper ions can promote contact killing by the generation of ROS. Chitosan not only enhanced antibacterial activities due to amine groups, but enabled it to be a template to load copper ions. We observed that multi-coated PET textiles have both antibacterial activities for E. coli and S. aureus and antiviral efficiency of more than 99.9% for influenza A (H1N1) and SARS-CoV-2. The multi-coated PET textiles could also be prepared via a roll-to-roll coating process, which showed high antiviral efficacy, demonstrating its potential use in air filtration and antiviral products such as masks and personal protective equipment.