• Title, Summary, Keyword: Microbalance

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Electrochemical Reactions of $C_{60}$ Films in the Presence of Water : An Electrochemical Quartz Crystal Microbalance Study

  • 서경자;신명순;전일철
    • Bulletin of the Korean Chemical Society
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    • v.17 no.9
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    • pp.781-786
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    • 1996
  • Mass transport behavior of C60 films on electrodes with different thicknesses has been studied by an Electrochemical Quartz Crystal Microbalance (EQCM) during electrochemical reduction-oxidation processes in the presence of water. C60 films were found to be reduced in the presence of water and they remains quite stable. In thin films, the mass on electrode decreased after a complete cycle while X-ray Photoelectron Spectroscopy (XPS) study does not support the existence or formation of C60-epoxides during electrochemical reduction processes in the presence of water or oxygen.

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Gas Response and Electrical Properties of Organic Ultra-thin Films (유기 박막의 전기적 특성 및 가스 반응 특성)

  • 박재철
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.10
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    • pp.820-825
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    • 1998
  • We deposited stearic acid LB films by using Langmuir-Blodgett (LB)method and investigated anisotropy electrical conduction characteristics by I-V measurement for horizontal direction and vertical direction. Also, we measured gad response between deposited LB films and organic gas for various temperature(0~8$0^{\circ}C$) by 9MHz At-cut quartz crystal microbalance. The LB films have electrical conduction characteristics such as semiconducting and insulating properties. The is, the conductivity of LB films for the horizontal and vertical direction is about 10\ulcornerS/cm and 10\ulcorners/cm, respectively. the frequency shift of stearic acid LB films for the organic gases depended on the mass change by the surface adsorption and the inner penetration to the sensing films. The resonant frequency shift of the quartz crystal microbalance for temperature properties of LB films is thought to the effect of the rearrangement or the damage pf LB films above the melting point and the mobility increasement of the organic gas by the temperature rising.

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The Determination of Diffusion and Partition Coefficients of PUF (폴리우레탄 폼의 휘발성 유기화합물 확산 및 분배계수 산정)

  • Park, Jin-Soo;Little, John C.;Kim, Shin-Do;Lee, Hee-Kwan;Kong, Boo-Ju
    • Journal of Korean Society for Atmospheric Environment
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    • v.26 no.1
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    • pp.77-84
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    • 2010
  • The diffusion and partition coefficients of polyurethane foam (PUF) are estimated using a microbalance experiment and small chamber test. The microbalance is used to measure sorption/desorption kinetics and equilibrium data. When the diffusion condition is controlled in the chamber of the sample, interactions between volatile organic compounds (VOCs) and PUF can lead to the estimation of a relatively homogenous rate of mass transfer in the interiors and surfaces of PUF. The estimates of the material/air partition coefficient (K) and the material-phase diffusion coefficient (D) are shown to be independent of the concentrations of VOCs. This approach, if applied to a diffusion-controlled or physically-based model, can facilitate more precise prediction of their source/sink behavior. Although further research and more rigorous validation is needed, an emission model applied with the diffusion and partition coefficients from this research holds promise for the improvement of reliability in predicting the behavior of VOCs emitted from porous building materials by D and K.

Rapid Detection of Ovarian Cancer from Immunized Serum Using a Quartz Crystal Microbalance Immunosensor

  • Chen, Yan;Huang, Xian-He;Shi, Hua-Shan;Mu, Bo;Lv, Qun
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.7
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    • pp.3423-3426
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    • 2012
  • Background: The objective of this study was to measure the antibody content of NuTu-19 ovarian cancer cells in serum samples using a quartz crystal microbalance (QCM) immunosensor. Materials and Methods: NuTu-19 cells were first cultured onto the electrode surfaces of crystals in Dulbecco's modified Eagle medium, and then specified amounts of immunized serum samples of immunized rabbit were also added. The change in mass caused by specific adsorbtion of antibodies of NuTu-19 to the surfaces of the crystals was detected. Results: The change in resonance frequency of crystals caused by immobilization of NuTu-19 cells was from 83 to 429Hz. The antibody content of NuTu-19 detected was 341ng/ul. The frequency shifts were linearly dependent on the amount of antibody mass in the range of 69 to 340ng. The positive detection rate and the negative detection rate were 80% and 100%, respectively. Conclusion: This immunoassay provides a viable alternative to other early ovarian cancer detection methods and is particularly suited for health screening of the general population.

Surface Charge Transfer of Self-Assembled Viologen Derivative Using Quartz Crystal Microbalance (수정진동자를 이용한 자기조립된 Viologen 유도체의 계면전하이동 특성)

  • Park, Sang-Hyun;Ryu, Kil-Yong;Lee, Dong-Yun;Kwon, Young-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.256-257
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    • 2005
  • 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. The viologen derivative exist in three redox states, namely. These redox reactions are highly reversible and can be cycled many times without significant side reactions, respectively. We studied the characteristics of charge transfer using different electrolyte solutions by electrochemical quartz crystal microbalance (EQCM). From the data, the redox peak currents were nearly equal charges during redox reaction and existed to an excellent linear interrelation between the scan rates and first redox peak currents. The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redox reactions.

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The Determination of Diffusion and Partition Coefficients of Indoor Bottom Finishing Materials (바닥재의 확산계수 및 분배계수 산정)

  • Park, Jin-Soo;Little, John C.;Kim, Shin-Do;Yun, Joong-Seop
    • Journal of Environmental Health Sciences
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    • v.34 no.3
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    • pp.219-225
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    • 2008
  • Many building materials may contain high concentrations of volatile organic compounds (VOCs) and other hazardous pollutants(HAPs). Specifically, VOCs discharged by indoor building material may cause "new house" syndrome, atopic dermatitis etc. The diffusion coefficient and initially contained total VOC quantity were determined using microbalance experiments and small chamber tests. Interactions between volatile organic compounds (VOCs) and vinyl flooring (VF), a relatively homogenous, diffusion-controlled building material, were characterized. Rapid determination of the material/air partition coefficient (K) and the material-phase diffusion coefficient (D) for each VOC was achieved by placing thin VF slabs in a dynamic microbalance and subjecting them to controlled sorption/desorption cycles. K and D are shown to be independent of concentration for all of the VOCs and water vapor. This approach can be applied to other diffusion-controlled materials and should facilitate the prediction of their source/sink behavior using physically-based models.

Adsorption of Aromatic Compounds on a QCM System Coated with Polymer Films (고분자 필름이 코팅된 QCM 시스템에 의한 방향족 화합물의 흡착)

  • Hwang, Min-Jin;Shim, Wang-Geun;Moon, Hee
    • Korean Chemical Engineering Research
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    • v.51 no.2
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    • pp.233-239
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    • 2013
  • A quartz crystal microbalance (QCM) system coated with poly (isobutylene), polystyrene, and poly (methyl methacrylate) has been prepared to measure the adsorption amounts of benzene, toluene, and p-xylene at very low pressures. The resonant frequency shift of the QCM system is proportional to the increase in pressure in all experiments. The Henry's constants for all adsorbates on the polymer films are obtained from experimental data and compared with the minimum adsorption potential energies between adsorbates and the polymer films. In general, there is an explicit correlation between adsorption amount and the minimum adsorption potential energy.