• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.258-263
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• 2017

In this study, we synthesized biocatalyst consisting of glucose oxidase (GOx), polyethyleneimine (PEI) and carbon nanotube (CNT) with addition of p-benzoquinone (BQ) that was considered anodic catalysts of enzymatic biofuel cell (EBC). For doing this, PEI/CNT supporter was bonded with BQ by physical entrapping method stemmed from electrostatic attractive force ([BQ/PEI]/CNT). In turn, GOx moiety was further immobilized on the [BQ/PEI]/CNT to form GOx/[BQ/PEI]/CNT catalyst. This catalyst has a special advantage in that the BQ that has been usually dissolved into electrolyte was immobilized on supporter. According to the electrochemical analysis, maximum current density of the GOx/[BQ/PEI]/CNT catalyst was 1.9 fold better than that of the catalyst that did not entrap BQ with the value of $34.16{\mu}A/cm^2$, verifying that catalytic activity of the catalyst was enhanced by adoption of BQ. Also, when it was used as anodic catalyst of the EBC, its maximum power density was 1.2 fold better than that of EBC using the catalyst that did not entrap BQ with the value of $0.91mW/cm^2$. Based on such results, it turned out that the GOx/[BQ/PEI]/CNT catalyst was promising and viable as anodic catalyst of EBC.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.1-4
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• 2019

In this study, an anthracene cross-linker is introduced to enhance the catalytic activity of glucose oxidase (GOx) based catalysts and to increase the amount of enzyme loading. The crosslinked GOx is bonded with the CNT/PEI support using the electrostatic interaction (AC[CNT/PEI/GOx]). Electrochemical evaluations are done to evaluate the performance of this catalyst and the performance of CNT/PEI/GOx catalyst is also measured as a control. According to the measurements, it is confirmed that the amount of loaded GOx increases, while $K_m$ value calculated by Lineweaver-Burk plot shows that AC[CNT/PEI/GOx] ($K_m$ : 0.73 mM) is superior to CNT/PEI/GOx ($K_m$ : 1.71 mM) without cross-linking reaction. Based on these effects, it is demonstrated that the maximum power density of the enzymatic biofuel cell using AC[CNT/PEI/GOx] increases from $21.2{\mu}W/cm^2$ to $57.4{\mu}W/cm^2$.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.1
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• pp.101-110
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• 2020

Transient receptor potential canonical 4 (TRPC4) channel is a nonselective calcium-permeable cation channels. In intestinal smooth muscle cells, TRPC4 currents contribute more than 80% to muscarinic cationic current (mIcat). With its inward-rectifying current-voltage relationship and high calcium permeability, TRPC4 channels permit calcium influx once the channel is opened by muscarinic receptor stimulation. Polyamines are known to inhibit nonselective cation channels that mediate the generation of mIcat. Moreover, it is reported that TRPC4 channels are blocked by the intracellular spermine through electrostatic interaction with glutamate residues (E728, E729). Here, we investigated the correlation between the magnitude of channel inactivation by spermine and the magnitude of channel conductance. We also found additional spermine binding sites in TRPC4. We evaluated channel activity with electrophysiological recordings and revalidated structural significance based on Cryo-EM structure, which was resolved recently. We found that there is no correlation between magnitude of inhibitory action of spermine and magnitude of maximum current of the channel. In intracellular region, TRPC4 attracts spermine at channel periphery by reducing access resistance, and acidic residues contribute to blocking action of intracellular spermine; channel periphery, E649; cytosolic space, D629, D649, and E687.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.630-638
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• 2001

The electrical resistivity of sinter dusts generated from the steel industry and coal fly ash from the coal power plant has been investigated using the high voltage conductivity cell based on JIS B 9915 as a function of temperature and water content. Dust characterization such as the chemical composition, size distribution, atomic concentration, and surface structure has been conducted. Major constituents of sinter dusts were Fe$_2$O$_3$(40∼74.5%), CaO (6.4∼8.2%), SiO$_2$(4.1∼6.0%), and unburned carbon (7.0∼14.7%), while the coal fly ash consisted of mainly SiO$_2$(51.4%), Al$_2$O$_3$(24.1%), and Fe$_2$O$_3$(10.5%). Size distributions of the sinter dusts were bi-modal in shape and the mass median diameters (MMD) were in the range of 24.7∼137㎛, whereas the coal fly ash also displayed bi-modal distribution and the MMD of the coal fly ash was 35.71㎛. Factors affecting resistivity of dusts were chemical composition, moisture content, particle size, gas temperature, and surface structure of dust. The resistivity of sinter dusts was so high as 10(sup)15 ohm$.$cm at 150$\^{C}$ that sinter dust would not precipitate well. The resistivity of the coal fly ash was measured 1012 ohm$.$cm at about 150$\^{C}$. Increased water contents of the ambient air lowered the dust resistivity because current conduction was more activated for absorption of water vapor on the surface layer of the dust.

• Macromolecular Research
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• v.12 no.1
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• pp.46-52
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• 2004

In a continuation of our previous studies on blood compatibility profiles of anion-substituted poly(vinyl alcohol) (PVA) membranes, in which hydroxyl groups have been replaced with carboxymethyl (C-PVA) and sulfonyl groups (S-PVA), we have studied the activation of complement components and the changes in white cell and platelet count in vitro and compared them with those of unmodified PVA, Cuprophane, and low-density polyethylene. Complement activation of fluid phase components, C3a, Bb, iC3b, and SC5b-9, and of bound phases, C3c, C3d, and SC5b-9, were assessed by enzyme-linked immunosorbent assay (ELISA) and immunoblot, respectively. The changes in the number of white cells and platelets following complement activation were counted using a Coulter counter. C-PVA and S-PVA activated C3 to a lesser extent than did PVA, which we attribute to the diminished level of surface nucleophiles of the samples. In addition, C- and S-PVA exhibit increased inhibition of Bb production, resulting in a decrease in the extent of C5 activation. Consequently, because of the reduced activation of C3 and C5, C- and S-PVA samples cause marked decreases in the SC5b-9 levels in plasma. We also found that the negatively charged sulfonate and carboxylate groups of the samples cause a greater extent of adsorbtion of the positively charged anaphylatoxins, C3a and C5a, because of strong electrostatic attraction, which in turn provides an inhibition of chemotaxis and activation of leukocytes. The ability to inhibit complement production, together with the binding ability of anaphylatoxins of the C- and S-PVA samples, leads to a prominent decrease in lysis of leukocytes as well as activation of platelets.

• Bulletin of the Korean Chemical Society
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• v.13 no.1
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• pp.70-74
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• 1992

Two crystal structures of ethylene (a= 12.272(2) ${\AA}$) and acetylene (a = 12.245(2) ${\AA}$) sorption complexes of dehydrated fully $Ca^{2+}$-exchanged zeolite A have been determined by single crystal X-ray diffraction techniques in the cubic space group, Pm3m at $21(1)^{\circ}C$. Their complexes were prepared by dehydration at $360^{\circ}C$ and $2{\times}10^{-6}$ Torr for 2 days, followed by exposure to 200 Torr of ethylene gas and 120 Torr of acetylene gas both at $24^{\circ}C$, respectively. The structures were refined to final R (weighted) indices of 0.062 with 209 reflections and 0.098 with 171 reflections, respectively, for which I > 3${\sigma}$(I). The structures indicate that all six $Ca^{2+}$ ions in the unit cell are associated with 6-oxygen ring of the aluminosilicate framework. Four of these extend somewhat into the large cavity where each is coordinated to three framework oxide ions and an ethylene molecule and/or an acetylene molecule. The carbon to carbon distance in ethylene sorption structure is 1.48(7) ${\AA}$ and that in acetylene sorption structure 1.25(8) ${\AA}$. The distances between $Ca^{2+}$ ion and carbon atom are 2.87(5) ${\AA}$ in ethylene sorption structure and 2.95(7) ${\AA}$ in acetylene sorption structure. These bonds are relatively weak and probably formed by the electrostatic attractions between the bivalent $Ca^{2+}$ ions and the polarizable ${\pi}$-electron density of the ethylene and/or acetylene molecule.

• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1222-1227
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• 1998

The crystal structure of a benzene sorption complex of fully dehydrated Cd2+-exchanged zeolite X, Cd46Si100Al92O384·43C6H6 (a=24.880(6) Å), has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at 21 ℃. The crystal was prepared by ion exchange in a flowing stream of 0.05 M aqueous Cd(NO3)2 for 3 d, followed by dehydration at 400 ℃ and 2 x 10-6 Torr for 2 d, followed by exposure to about 92 Torr of benzene vapor at 22 ℃. The structure was determined in this atmosphere and refined to the final error indices R1=0.054 and Rw=0.066 with 561 reflections for which I > 3σ(I). In this structure, Cd2+ ions are found at four crystallographic sites: eleven Cd2+ ions are at site 1, at the centers of the double six-oxygen rings; six Cd2+ ions lie at site I', in the sodalite cavity opposite to the double six-oxygen rings; and the remaining 29 Cd2+ ions are found at two nonequivalent threefold axes of unit cell, sites Ⅱ' (in the sodalite cavity ) and site Ⅱ (in the supercage) with occupancies of 2 and 27 ions, respectively. Each of these Cd2+ ions coordinates to three framework oxylkens, either at 2.173(13) or 2.224(10) Å, respectively, and extends 0.37 Å into the sodalite unit or 0.60 Å into the supercage from the plane of the three oxygens to which it is bound. The benzene molecules are found at two distinct sites within the supercages. Twenty-seven benzenes lie on threefold axes in the large cavities where they interact facially with the latter 27 site-Ⅱ Cd2+ ions (Cd2+-benzene center=2.72 Å; occupancy=27 molecules/32 sites). The remaining sixteen benzene molecules are found in 12ring planes; occupancy=16 molecules/16 sites. Each hydrogen of these sixteen benzenes is ca. 2.8/3.0 Å from three 12-ring oxygens where each is stabilized by multiple weak electrostatic and van der Waals interactions with framework oxygens.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.371-378
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• 2021

The formation of hydrophilic surface based on polymers has received great attention due to the anti-adhesion of bacteria on solid substrates. Anti-adhesion coatings are aimed at suppressing the initial step of biofilm formation via non-cytotoxic mechanisms, and surfaces applied hydrophilic or ionic polymers showed the anti-adhesion effect for bioentities, such as proteins and bacteria. This is attributed to the formation of surface barrier from hydration layers, repulsions and osmotic stresses from polymer brushes, and electrostatic interactions between ionic polymers and cell surfaces. The antifouling polymer coating is usually fabricated by the grafting method through the bonding with functional groups on surfaces and the deposition method utilizing biomimetic anchors. This mini-review is a summary of representative antifouling polymers, coating strategies, and antibacterial efficacy. Furthermore, we will discuss consideration on the large area surface coating for application to public facilities and industry.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.91-97
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• 2011

The efficacies of anti-atopic preparations were investigated in hairless mice suffering from 2,4-dinitro-chlorobenzene (DNCB)-induced atopic dermatitis-like lesion. Solid lipid nanoparticle (SLN) containing ceramide and astaxanthin was prepared by a melt-homogenization method using Aminsoft-CT 12 (Cocoyl glutamate) as an emulsifier. And then, the SLNs were coated with silk fibroin (SF) by taking advantage of an electrostatic interaction between the surface of SLNs and SF. SLNs were included in lotion (FL) and cream (FC) types of preparations. Anti-atopic efficacies of the preparations were investigated in terms of appearance of skin surface, spleen index, serum IgE level, and serum cytokine level. SLN-containing preparations suppressed IgE production and IL-4 expression, but promoted $IFN-{\gamma}$ expression.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.63-63
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• 2012

전자제품 패키지에 요구되는 쿠션성과 정전방전 기능을 갖는 폴리우레탄 발포 필름의 제조기술을 확립하게 되면 IT산업용에 적용 가능한 필름제품이 개발되어 ESD(정전방전, Electrostatic Dissipation) 성능을 발휘하게 됨으로서 정전기 쇼크에 의한 각종 전자제품의 오작동이나 파손 방지가 가능하게 되어 포장재, 자동차 전자제품의 하우징 등으로 사용될 수 있게 된다. 전도성 고분자인 Polyaniline (PANI)은 다른 여러 고분자와 비교하여 볼 때 다른 유형의 전도성 고분자보다 합성하기가 쉽고 높은 전기전도도를 보임은 물론 열적 및 대기 안정성이 우수하며 가격이 저렴한 장점을 가지고 있다. 본연구는 CNT 나노기술을 응용한 IT산업용 적층간지용 ESD PU발포필름의 제조 가공기술 및 상품화 개발을 수행하고자 방수, 투습방수성을 가지는 유연재료인 폴리우레탄(PU)의 1액형 PU와 DMF에 PANI의 함량을 5, 10, 15, 20, 25, 30wt%로 변화시켜 제조한 PANI/DMF 분산용액과 IPA/MWNT 3wt% 분산용액의 혼용비에 변화를 주어 $120^{\circ}C$에서 2분 건조시켜 그라운드 필름을 제조하였다. 그리고 2액형 PU와 IPA/MWNT 3wt% 분산용액과 발포제를 사용하여 발포온도 $150^{\circ}C$에서 5분간 건조시켜 발포필름을 제조하였으며 이들의 전기적 특성과 역학적 특성을 조사하였다. 제조된 필름의 전기전도성은 전기저항측정기 KEITHLEY 8009를 사용하여 부피저항과, 표면저항을 각각 측정하여 확인하였으며, 필름의 마찰 대전압은 E.S.T-7 마찰 대전압 시험기를 이용하여 표면 마찰 대전압을 측정하여 확인하고, 필름의 물리적 특성은 인장시험기를 이용하여 breaking stress, breaking strain을 측정하였다. 필름단면의 CNT 발포특성은 주사전자현미경(SEM)을 사용하여 측정하여 발포특성과 물성과의 연관성을 확인하였다. 그 결과 필름의 전기적 특성은 PANI가 30% 함량일 때 전반적으로 낮은 저항값이 측정되었으며, 마찰대전압을 측정한 결과 대부분의 시료가 0에 가까운 낮은 값을 가졌다. 필름의 물리적 인장특성은 PANI가 10wt%의 함량일 때 가장 높은 절단강도를 가졌으며 분산용액의 혼용비에 따른 경향성은 나타나지 않았다. 필름의 단면형상을 확인하여 발포특성을 분석한 결과 PANI의 함량에 따라 발포 cell의 크기는 뚜렷한 경향성을 보이지 않았으나 30wt%의 PANI/DMF 분산용액 20part(gr)와 3wt% IPA/MWNT 분산용액 40part(gr)로 제조한 시료의 cell이 가장 균일하고 고르게 발포되었으며, 3.90E+06ohm으로 가장 낮은 표면저항 값으로 측정되어 가장 좋은 전기전도성을 가짐을 확인하였다.