• Title/Summary/Keyword: Microbalance

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Interfacial Properties of Imidazoline Cationic Surfactant (Imidazoline 양이온 계면활성제의 계면 특성)

  • Kim, Ji Sung;Lim, Jong Choo
    • Korean Chemical Engineering Research
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    • v.47 no.1
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    • pp.38-45
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    • 2009
  • In this study, interfacial properties were measured for imidazoline type cationic surfactant system which has been widely used as a fabric softener, a dispersant, an anti-static agent, a bleach activator, and an emulsifier. The CMC of imidazoline surfactant was near $6{\times}10^{-5}mol/L$ and the surface tension at CMC was about 32 mN/m. It was found that surface tension was not affected by surfactant concentration but decreased with an increase in pH. The interfacial tension between 1 wt% aqueous solution and n-dodecane was shown to be about 0.01 mN/m and equilibration time was not affected by pH. Phase behavior experiment in a binary aqueous surfactant system showed that only micellar solution of $L_1$ phase was found under conditions of temperature and pH investigated during this study. Only a two-phase region consisting of lower-phase microemulsion in equilibrium with excess oil phase existed under the same conditions, when oil was added to the binary surfactant system. The foam stability measured with 1 wt% surfactant solution increased with pH, which is consistent with surface tension measurement result. QCM(quartz crystal microbalance) measurement showed that surfactant adsorption increased with surfactant concentration but decreased with pH. According to the friction measurement, best fabric softening effect by imidazoline surfactant system was found under alkali conditions.

Comparison of Enzymatic Activity and Cleavage Characteristics of Trypsin Immobilized by Covalent Conjugation and Affinity Interaction (공유결합과 친화력결합에 의한 고정화 Trypsin의 효소역가와 절단특성 비교)

  • Jang, Dae-Ho;Seong, Gi-Hun;Lee, Eun-Kyu
    • KSBB Journal
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    • v.21 no.4
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    • pp.279-285
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    • 2006
  • We investigated the effects of immobilization chemistry on the yield of immobilization and the bioactivity of the immobilized enzymes. Trypsin as a model protein and macroporous polymer beads(Toyopearl AF 650M, Tosho Co., Japan) was used as a model matrix. Four methods were used to immobilize trypsin; covalent conjugation by reductive amination(at pH 10.0 and pH 4.0) and affinity interaction via streptavidin-biotin, and double-affinity interaction via biotin-streptavidin-biotin system. The covalent conjugation immobilized $3{\sim}4$ mg/ml-gel, ca. 3-fold higher than the affinity method. However, the specific activity of the covalently(pH 10.0) and affinity-immobilized trypsin(via streptavidin-biotin) are ca. 37% and 50%, respectively, of that of the soluble enzyme(on the low-molecular-weight BAPNA substrate). When the molecular size of a substrate increased, the affinity-immobilized trypsin showed higher clavage activity on insulin and BSA. This result seemed to indicate the streptavidin-biotin system allowed more steric flexibility of the immobilized trypsin in its interaction with a substrate molecule. To confirm this, we studied the molecular flexibility of immobilized trypsin using quartz crystal microbalance-dissipation. Self-assembled monolayers were formed on the Q-sensor surface by aminoalkanethiols, and gultaraldehyde was attached to the SAMs. Trypsin was immobilized in two ways: reductive amination(at pH 10.0) and the streptavidin-biotin system. The dissipation shift of the affinity-immobilized trypsin was $0.8{\times}10^{-6}$, whereas that of the covalently attached enzyme was almost zero. This result confirmed that the streptavidin-biotin system allowed higher molecular flexibility. These results suggested that the bioactivity of the immobilized enzyme be strongly dependent on its molecular flexibility.

Effect of pH on Physical Properties of Triethanolamine-Ester Quaternary Ammonium Salt Cationic Surfactant System (수용액의 pH가 Triethanolamine-Ester Quaternary Ammonium Salt 양이온 계면활성제 시스템의 물성에 미치는 영향에 관한 연구)

  • Kim, JiSung;Lim, JongChoo
    • Applied Chemistry for Engineering
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    • v.20 no.5
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    • pp.479-485
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    • 2009
  • In this study, basic physical properties were measured for ASCO EQ85 cationic surfactant of triethanolamine-ester quaternary ammonium salt and effect of pH on softening performance on fabrics was investigated using zeta potential measurement and adsorption experiment by quartz crystal microbalance. The CMC of the surfactant was near $3{\times}10^{-3}mol/L$ and the surface tension at CMC was about 40 mN/m. The interfacial tension measurement between 1 wt% aqueous solution and n-dodecane measured by spinning drop tensiometer showed that interfacial tension slightly increased with an increase in pH but the equilibration time was not affected by pH. The surfactant adsorption was found to increase with an increase in surfactant concentration and was also affected by pH of surfactant solution. The friction factor for fabrics treated with ASCO EQ85 surfactant was shown to increase with pH and better softening effect was found under acidic conditions. Half-life for foams generated with ASCO EQ85 surfactant solution increased with pH, which indicated an increase in foam stability with pH.

A Study on the contamination measurement of spacecraft components under High Vacuum Environment (고진공하에서의 위성체 부품의 오염측정에 관한 연구)

  • 이상훈;서희준;문귀원;최석원
    • Journal of the Korean Vacuum Society
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    • v.11 no.2
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    • pp.87-96
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    • 2002
  • Outgassing from such sources as paints, coatings, adhesives and other non-metallic surfaces can contaminate satellites, especially second surface mirror and optical lens, it cause satellite to fail in own missions. The vacuum bake-out test using high temperature(more than $85 ^{\circ}C$)and high vacuum(less than $5.0{\times}1-^{-3}$ Pa) certify that the components of satellite work properly and can survive and operate in space environment like high vacuum. In the bake-out chamber installed at SITC of KARI, Rotary vacuum pump and Booster pump produce low vacuum of 5.0 Pa, and then two cryopumps produce high vacuum of below $5.0{\times}10^{-3}$ Pa. Also 48 ceramic heaters were provided to simulate high temperature. During the vacuum bake-out test, we detected contaminants using RGA(Residual Gas Analyzer) and measure the outgassing rate of the contaminant using the TQCM(Thermoelectric Quartz Crystal Microbalance). Also, IR/UV Spectrometer and witness plate be used to certify that the components were suitable for the spacecraft. This paper includes the preparation and procedures of the bake-out test for SAR(Solar Array Regulator) and MLI(Multi Layer Insulator), which were the components of the spacecraft. Especially, we discussed the methods and results of the contamination measurement. In the bake-out for SAR, the contamination was measured continuously although it was on the decrease from TQCM results. And RCA established that it is a highly polymerized compound. In the MLI bake-out using RGA and witness plate, we didn't detect any contamination materials.

Measurement of an Isoelectric Point and Softness of a Zwitterionic Surfactant (양쪽성 계면활성제의 등전점 및 유연력 측정에 관한 연구)

  • Lim, Jongchoo;Kim, Jisung;Mo, Dahee;Lee, Jinsun
    • Applied Chemistry for Engineering
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    • v.23 no.1
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    • pp.112-118
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    • 2012
  • In this study, physical properties of synthesized DE7-OSA82-AO and DEP52-OSA82-AOQ82 zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle and viscosity. Phase behavior study was also performed. The dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which was attained using zeta potential measurements and QCM (quartz crystal microbalance) experiments. The isoelectric point of DE7-OSA82-AO surfactant determined by the zeta potential measurement and QCM experiment was about 7.2 and 7.4, respectively. On the other hand, the isoelectric point of DEP52-OSA82-AOQ82 surfactant determined by the zeta potential measurement and QCM experiment was about 10.9 and 11.0, respectively. The frictional property measured using an automated mildness tester showed that DE7-OSA82-AO surfactant can provide a good softening effect at an acidic or neutral condition. On the other hand, DEP52-OSA82-AOQ82 was found to provide a good softening effect to a fabric surface at a pH below its isoelectric point of 11.

Gas Sorption Analysis of Metal-organic Frameworks using Microresonators (마이크로진동자 기반 금속유기골격체의 기체 흡탈착 분석)

  • Kim, Hamin;Choi, Hyun-Kuk;Kim, Moon-Gab;Lee, Young-Sei;Yim, Changyong
    • Applied Chemistry for Engineering
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    • v.33 no.1
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    • pp.11-16
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    • 2022
  • Metal-organic frameworks (MOFs) are porous materials with nano-sized pores. The degree of gas adsorption and pore size can be controlled according to types of metal ions and organic ligands. Many studies have been conducted on MOFs in the fields of gas storage and separation, and gas sensors. For rapid and quantitative gas adsorption/desorption analyses, it is necessary to form various MOF structures in uniform films on a sensor surface. In this review, some of representative direct methods for uniformly synthesizing MOFs such as MIL-53 (Al), ZIF-8, and Cu-BDC from anodized aluminum oxide, zinc oxide nanorods, and copper thin films, respectively on the surface of a microresonator are highlighted. In addition, the operation principle of quartz crystal microbalance and microcantilever, which are representative microresonators, and the interpretation of signals that change when gas is adsorbed to MOFs are covered. This is intended to enhance the understanding of gas adsorption/desorption analysis of MOFs using microresonators.

Gas Separation Membranes Containing $Re_6Se_8(MeCN)_6^{2+}$ Cluster-Supported Cobalt-Porphyrin Complexes

  • Park Su Mi;Won Jongok;Lee Myung-Jin;Kang Yong Soo;Kim Se-Hye;Kim Youngmee;Kim Sung-Jin
    • Macromolecular Research
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    • v.12 no.6
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    • pp.598-603
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    • 2004
  • Cellulose nitrate (CN) composite membranes, containing cobalt porphyrin (CoP) complexes self-assembled within nanometer-sized rhenium clusters (ReCoP), have been prepared and their oxygen and nitrogen gas perme­abilities were analyzed. The solubility of ReCoP and the characteristics of the corresponding composite membranes were analyzed using a Cahn microbalance, FT-IR spectroscopy, wide-angle X-ray scattering, and differential scanning calorimetry. The nitrogen permeability through the CN composite membranes decreased upon addition of ReCoP and CoP, which implies that the presence of these oxygen carrier complexes affects the structure of the polymer matrix. The oxygen permeability through the composite membranes containing small quantities of ReCoP decreased, but it increased upon increasing the concentration. The oxygen gas transport was affected by the matrix at low ReCoP concentrations, but higher concentrations of ReCoP increased the oxygen permeability as a result of its reversible and specific interactions with oxygen, effectively realizing ReCoP carrier-mediated oxygen transport.

Precision Measurement of Ultrasonic Power the Milliwatt Range (밀리와트 영역의 초음파 파워 정밀 측정)

  • Jho, Moon-Jae;Hwang, Cheol-Ho;Suh, Sang-Joon;Cha, Il-Whan
    • The Journal of the Acoustical Society of Korea
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    • v.9 no.2
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    • pp.25-33
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    • 1990
  • An ultrasonic power measurement system in milliwatt range was constructed. The ultrasonic power can be determined by measuring the radiation pressure on a target using self-compensating microbalance. Measurement was performed using a perfect reflector and a perfect absorber. In order to check the feasibility of the system, the ultrasonic power for the two targets was measured. Also, the systematic measurement errors and the reproducibility were examined. The relative error between two targets is proved to be within 2%. Also when the ultrasonic power range is larger than 10mW, the standard deviation for repeated measurement becomes smaller than ${\pm}$2%.

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Chemisorption of Thiolated Listeria monocytogenes-specific DNA onto the Gold Surface of Piezoelectric Quartz Crystal

  • Ryu, Sung-Hoon;Jung, Sang-Mi;Kim, Namsoo;Kim, Woo-Yeon
    • Journal of Applied Biological Chemistry
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    • v.44 no.4
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    • pp.163-166
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    • 2001
  • Piezoelectric (PZ) crystal biosensor system was used to detect the DNA of food pathogenic Listeria monocytogenes. L. monocytogenes-specific DNA was multiplied via the polymerase chain reaction using LM1 oligonucleotide (5'-TTACGAATTAAAAAGGAGCG-3') and LM2 oligonucleotide (5'-TTAAATCAGCAGGGGTCTTT-3') as primers. DNA fragment of 161 bp, which was specific only for L. monocytogenes, was observed. To obtain a large amount of single-stranded DNA containing an SH group used for coupling to the gold electrode chemisorptively, LM1 oligonucleotide containing a mercaptohexyl group was utilized as a single strand PCR primer. The PCR product was immobilized onto the gold electrode of PZ crystal, and hybridization was monitored in quartz crystal microbalance (QCM) system by injecting the antisense single-stranded DNA of 161 nucleotides obtained via the single strand PCR using the unmodified LM2 primer. Approximately 70 Hz of frequency drop was observed in the QCM system in the case of two consecutive injections of $5{\mu}g$ of the antisense single-stranded DNA.

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Sensing and Degradation Characteristics in the QCM Gas Sensor Coated with the PVC and PC (PVC 및 PC 혼합액을 코팅한 QCM 가스센서의 센싱 및 열화 특성)

  • Jang, Kyung-Uk;Kim, Myung-Ho;Lee, Joon-Ung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.04b
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    • pp.176-179
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    • 2000
  • In the recognition of the gases using the quartz crystal microbalance (QCM) coated with the film materials, it is important to obtain the recognition ability of gases, and the stability of film coated above the QCM. Especially, the thickness of film coated above the QCM is decreased according with the using circumstance and time of QCM gas sensor. Therefore, the sensing chararcteristics of film is changed with these. In this paper, we coated the lipid PC (Phosphatidyl Choline) materials varing with the blended amount of PVC(Poly Vinyl Chloride) and solution (Tetra Hydrofan:THF) above QCM to obtain the stability of lipid PC film. QCM gas sensors coated with film materials were measured the frequency change in the chamber of stationary gas sensing system injected 1-hexane, ethyl acetate, ethanol and benzene of $20{\mu}{\ell}$, respectively. We obtained the principal component analysis (PCA) from the frequency change due to the absorption of gas. Also, we measured the degradation characteristics of QCM gas sensor to show the properties of stability.

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