• Title, Summary, Keyword: Microbalance

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Study on the Properties of Molecular Sieve Made from Carbonized Material with Modifiers (변형제를 이용한 탄화 시료의 분자체 특성 효과에 관한 연구)

  • Kim, Kweon-Ill;Kim, Tae-Hwan;Park, Jong-Gi;Cho, Sung-Chul;Jin, Myeng-Jong
    • Applied Chemistry for Engineering
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    • v.7 no.2
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    • pp.334-340
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    • 1996
  • Carbon adsorbents, having the properties of molecular sieve, were prepared based on coat materials. A couple of modifiers were used to prepare carbon molecular sieve. The effects of modifier concentrations on the characteristics of carbon molecular sieve were investigated. In order to verify the characteristics of carbon molecular sieve, the adsorption rates of oxygen and nitrogen gases on the carbon molecular sieve were measured using Cahn microbalance(model # : D-200). The experimental data were fitted to an adsorption rate equation and gas diffusivities were calculated. The effects of modifier molecular weight and concentration on the characteristics of carbon molecular sieve were shown.

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Study on Morphology Investigation and Charge-transfer Property of Self-assembled Viologen Monolayers (자기조립된 Viologen 단분자막의 표면이미지 관찰과 계면전하이동 특성 연구)

  • Park Sang-Hyun;Lee Dong-Yun;Park Jae-Chul;Kwon Young-Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.3
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    • pp.246-249
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    • 2006
  • We fabricated self-assembled monolayers(SAMs) onto quartz crystal microbalance(QCM) using viologen, which has been widely used as electron acceptor and electron transfer mediator. We determined the time dependence on resonant frequency shift during self-assembly process and observed the morphology of self-assembled monolayers by STM and investigated the electrochemical behavior of SAMs by cyclic voltammetry. Electrochemical deposition of viologen was investigated using electrochemical quartz crystal microbalance(EQCM). The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redok reactions. The total frequency change was about 9.5 Hz, and 7.1 Hz. From the data, we could know the mass change was about 10.16 ng and 7.60 ng, respectively. Finally, the EQCM has been employed to monitor the electrochemically induced adsorption of self-assembled monolayers on Au surfaces.

A New Concept for Efficient Sensitivity Amplification of a QCM Based Immunosensor for TNF-α by Using Modified Magnetic Particles under Applied Magnetic Field

  • Bahk, Yeon-Kyoung;Kim, Hyung-Hoon;Park, Deog-Su;Chang, Seung-Cheol;Go, Jeung-Sang
    • Bulletin of the Korean Chemical Society
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    • v.32 no.12
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    • pp.4215-4220
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    • 2011
  • This study introduces a new concept for a simple, efficient and cheap sensitivity amplification of a Quartz Crystal Microbalance (QCM) based immunosensor system for the detection of tumor necrosis factor-alpha (TNF-${\alpha}$, TNF) by using an in-built magnetic system. The frequency shift due to the applied magnetic field was successfully observed on magnetic particles labeled detection antibodies, anti-human TNF-${\alpha}$, which were bound to the immunologically captured TNF-${\alpha}$ on the gold coated quartz crystals. In the present system, the magnitude of frequency shift depends on both the strength of magnetic field and the amount of target antigen applied. Significant signal amplification was observed when the additional built-in residual stress generated by the modified magnetic particles under the magnetic field applied. Used in conjunction with a sandwich type non-competitive immunoassay format, the lower detection limit was calculated to be 25 $ngmL^{-1}$ and showed good linearity up to TNF-${\alpha}$ concentrations as high as 2.0 ${\mu}gmL^{-1}$. The sensitivity, most importantly, was improved up to 4.3 times compared with the same QCM system which was used only an antigen-antibody binding without additional magnetic amplification.

Phase Equilibrium Measurement of Gas Hydrate with Quartz Crystal Microbalance (QCM(Quartz Crystal Microbalance)을 이용한 가스 하이드레이트 상평형 측정 방법)

  • Lee, Bo Ram;Sa, Jeong-Hoon;Park, Da-Hye;Lee, Kun-Hong
    • 한국신재생에너지학회:학술대회논문집
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    • pp.150.1-150.1
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    • 2010
  • 가스 하이드레이트는 물분자와 저분자량의 가스분자가 고압과 저온에서 수소결합을 이루며 형성되는 결정성 화합물을 말한다. 최근 가스 하이드레이트의 물리적 특성과 형성 원리를 이용하여 다양한 분야로의 적용 연구가 수행되고 있는데 이의 효과적 달성을 위해서는 가스 하이드레이트의 상평형 연구가 필수적이다. 기존에 수행되는 상평형 실험 방법은 온도의 변화에 따라 하이드레이트를 해리시키고 압력의 변곡점을 찾는 것으로 최소 24시간이 소요되지만, 본 연구진이 제안하는 QCM을 이용한 방법은 1 ng의 무게에 1 Hz의 변화를 나타내는 수정진동자의 민감성을 이용한 것으로 약 2~3시간 내에 상평형 실험을 수행할 수 있고, 하이드레이트의 기억효과(Memory Effect)를 이용하여 연속적인 상평형 실험도 가능하다. 본 연구에서는 QCM 반응기의 원리 및 실험 방법에 대하여 설명하고 열역학적 촉진제를 첨가한 상평형 실험결과를 제시함으로써 상대적으로 저렴한 가격으로 다양한 촉진제와 억제제 첨가 시 나타나는 상평형 효과를 빠른 시간 내에 선별할 수 있는 방법으로 QCM을 이용한 방법을 제안하고자 한다.

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Novel Detection Technology for Glycated Hemoglobin using Gold Nanoparticles (금 나노입자를 이용한 새로운 당화혈색소의 검출 기술)

  • Lee, Soo Suk
    • Journal of Sensor Science and Technology
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    • v.25 no.6
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    • pp.435-439
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    • 2016
  • We report a novel detection technology for glycated hemoglobin (HbA1c) that is measured primarily to identify the three-month average plasma glucose concentration. In enzymatic measuring of glycated hemoglobin, the generated hydrogen peroxide was then used as a reducing agent of gold (III) for the synthesis of gold (0). Gold nanoparticles obtained from this novel approach were measured by optical and piezoelectric methods. In optical method, we have developed polymer based film-type sensor cartridge filled with all the reagents for glycated hemoglobin analysis and the cartridge worked very well having the detection limit of 0.53% of glycated hemoglobin. On the other hand, quartz crystal microbalance (QCM) sensors also have been developed to determine the abilities of surface modified QCM sensors at various levels of the concentration of glycated hemoglobin to bind gold nanoparticles and limit of detection was 0.90%. Finally, despite of relatively lower sensitivities of QCM sensor and film-type optical sensor than well-plate based optical detection, these two sensors were available to measure the glycated hemoglobin level for diabetes patients and normal person.

Removal of volatile organic compounds from air using activated carbon impregnated cellulose acetate electrospun mats

  • Patil, Kashyap;Jeong, Seonju;Lim, Hankwon;Byun, Hun-Soo;Han, Sangil
    • Environmental Engineering Research
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    • v.24 no.4
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    • pp.600-607
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    • 2019
  • Volatile organic compounds (VOCs) are released from various sources and are unsafe for human health. Porous materials are promising candidates for the adsorption of VOCs owing to their increased ratio of surface area to volume. In this study, activated carbon (AC) impregnated cellulose acetate (CA) electrospun mats were synthesized using electrospinning for the removal of VOCs from the air mixture of ACs, and CA solution was electrospun at different proportions (5%, 10%, and 15%) in a single nozzle system. The different AC amounts in the electrospun mats were distributed within the AC fibers. The adsorption capacities were measured for acetone, benzene, and dichloromethane, using quartz crystal microbalance. The results elicited an increasing adsorption capacity trend as a function of the impregnation of ACs in the electrospun mats, while their capacities increased as a function of the AC concentration. Dichloromethane resulted in a faster adsorption process than acetone and benzene owing to its smaller molecular size. VOCs were desorbed with the N2 gas purging, while VOCs were adsorbed at higher temperatures owing to the increased vapor pressures. The adsorption analysis using Dubinin-Astakhov equation showed that dichloromethane is more strongly adsorbed on mats.

Measurement of I-TEDA Removal Rate Using QCM in Supercritical Carbon Dioxide (초임계이산화탄소 하에서 QCM을 이8한 I-TEDA의 제거특성 측정)

  • Yoo, Jae-Ryong;Koh, Moon-Sung;Sung, Jin-Hyun;Lee, Jeong-Ken;Park, Kwang-Heon
    • Clean Technology
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    • v.14 no.2
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    • pp.110-116
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    • 2008
  • The radioactive wastes generated from the nuclear industry can be divided into the forms of solid, liquid, or gas. Radioactive methyl iodide, a gaseous radioactive waste, is absorbed by activated carbon with 5 wt% of Trietylenediamine (1,4-diazania-bicycle[2.2.2]octane, TEDA) impregnated on the surface. Methyl Iodide ($CH_3I$) is combined chemically with TEDA (the final product : I-TEDA). To recycle radioactive activated carbon, removal of I-TEDA from activated carbon is needed. A wet method for recycling impregnated active carbon was developed to remove radioactive I-TEDA using an acetonitrile solution, which produces lots of secondary wastes. We suggest the removal of I-TEDA by supercritical carbon dioxide with co-solvents. In this experiment, we used a quartz crystal microbalance (QCM) for measuring the removal rate of the I-TEDA. From the experimental results, methanol was found to be the optimum co-solvent, and the optimum conditions such as temperature, pressure, and co-solvent flow rate were obtained. Possibility of using supercritical fluid in the removal of I-TEDA from radioactive activated carbon was also discussed.

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Measurement of an Isoelectric Point and Softness of a EO-PO Adducted Zwitterionic Surfactant (EO-PO가 부가된 양쪽성 계면활성제의 등전점 및 유연력 측정에 관한 연구)

  • Lim, JongChoo;Mo, DaHee;Lee, JinSun;Park, JunSeok;Han, DongSung
    • Korean Chemical Engineering Research
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    • v.50 no.3
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    • pp.455-463
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    • 2012
  • In this study, the measurement of physical properties of ethylene oxide-propylene oxide adducted zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle, viscosity and foam stability. Also, the dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which were obtained using zeta potential measurement and QCM (quartz crystal microbalance) experiments. The isoelectric point of DEP-OSA82-AO zwitterionic surfactant determined by zeta potential measurement was close to that obtained by QCM experiment and both results have shown almost the same trend as that determined by the frictional property measured using an automated mildness tester. In particular, it has been observed that DEP32-OSA82-AO and DEP34-OSA82-AO surfactants provide better softening effect at a pH of acidic or neutral condition than at an alkaline condition. This result indicates that both surfactants act as a cationic surfactant at a pH of acidic or neutral condition and thus provide good softening effect during a rinsing cycle in the detergency process.

Introduction to Electrochemical Quartz Crystal Microbalance Technique for Leaching Study of Metals (금속 침출연구를 위한 전기화학적 미소수정진동자저울 기술 소개)

  • Kim, Min-seuk;Chung, Kyeong Woo;Lee, Jae-chun
    • Journal of the Korean Institute of Resources Recycling
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    • v.29 no.1
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    • pp.25-34
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    • 2020
  • Electrochemical Quartz Crystal microbalance is a tool that is capable of measuring nanogram-scale mass change on electrode surface. When applying alternating voltage to the quartz crystal with metal electrode formed on both sides, a resonant frequency by inverse piezoelectric effect depends on its thickness. The resonant frequency changes sensitively by mass change on its electrode surface; frequency increase with metal dissolution and decrease with metal deposition on the electrode surface. The relationship between resonant frequency and mass change is shown by Sauerbrey equation so that the mass change during metal dissolution can be measured in real time. Especially, it is effective in the case of reaction mechanism and rate studies accompanied by precipitation, volatilization, compound formation, etc. resulting in difficulties on ex-situ AA or ICP analysis. However, it should be carefully considered during EQCM experiments that temperature, viscosity, and hydraulic pressure of solution, and stress and surface roughness can affect on the resonant frequency. Application of EQCM was shown as a case study on leaching of platinum using aqueous chlorine for obtaining activation energy. A platinum electrode of quartz crystal oscillator with 1000 Å thickness exposed to solution was used as leaching sample. Electrogenerated chlorine as oxidant was purged and its concentration was controlled in hydrochloric acid solution. From the experimental results, platinum dissolution by chlorine is chemical reaction control with activation energy of 83.5 kJ/mol.

Resistance and Frequency Properties Analysis of QCM Coated with LB Films (LB막이 누적된 QCM의 저항 및 주파수 특성해석)

  • 강현욱;진철남;김정명;권명수
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.465-467
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    • 1997
  • The oscillating properties of quartz Crystal Microbalance(QCM) were analyzed by electrical measurement. We tried to analyze the properties of quartz crystal coated with Langmuir-Bladgett(LB) films using the frequency and resistance at resonance in the electrical equivalent circuit. The resonant frequency was decreased linearly as to layers of LB films, however, there are some gap between theoretical values, Sauerbrey's equation and experimental values. The resistance was increase nonlinearly as to layers.

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