• 한국미생물·생명공학회지
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• 제47권4호
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• pp.473-486
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• 2019

In the aquatic environment, microorganisms are predominantly organized as biofilms. Biofilms are formed by the aggregation of microbial cells and are surrounded by a matrix of extracellular polymeric substances (EPS) secreted by the microbial cells. Biofilms are attached to various surfaces, such as the living tissues, indwelling medical devices, and piping of the industrial potable water system. Biofilms formed from a single species has been extensively studied. However, there is an increased research focus on multispecies biofilms in recent years. It is important to assess the microbial mechanisms underlying the regulation of multispecies biofilm formation to determine the drinking water microbial composition. These mechanisms contribute to the predominance of the best-adapted species in an aquatic environment. This review focuses on the interactions in the multispecies biofilms, such as coaggregation, co-metabolism, cross-species protection, jamming of quorum sensing, lateral gene transfer, synergism, and antagonism. Further, this review explores the dynamics and the factors favoring biofilm formation and pathogen transmission within the drinking water distribution systems. The understanding of the physiology and biodiversity of microbial species in the biofilm may aid in the development of novel biofilm control and drinking water disinfection processes.

• 대한화학회지
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• 제39권3호
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• pp.143-149
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• 1995

낮은 농도에서 유기색소와 계면활성제 계의 흡수거동을 계산하기 위해 간단한 모델을 사용해보았다. 실험에서 얻어진 값에 3개의 파라미터가 포함되어 있는 결과식을 적용함으로써 이온쌍형성$(K_O)$, 회합체에 계면활성제 분자첨가의 경우$(K_S)$, 그리고 색소회합반응$(K_D)$에 대한 평형상수들을 계산하였으며 이값들을 이용하여 자유에너지를 계산하였다. $K_O$와 K_S$의 값들은 소수성에 원인이 있는 정전기적 상호작용에서 기대했던 것들보다 컸었고, $K_D$값들은 정전기적 반발력의 차폐효과로 간주할 수 있는 순수한 수용액에서의 알려진 회합값보다 약 10~20배 정도 높았다.

• Journal of Yeungnam Medical Science
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• 제17권1호
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• pp.1-11
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• 2000

Inhibition of cyclooxygenase(COX), and thus prevention of the formation of prostaglandins, provided a unifying explanation of the therapeutic and toxic actions of nonsteroidal anti-inflammatory drugs (NSAIDs). Recently, the discovery of the two isoforms of COX was made by molecular biologists studying neoplastic transformation in chick embryo cells. The constitutive enzyme, COX-1, is obviously responsible for the production of prostaglandins involved in housekeeping functions such as maintenance of integrity of the gastric mucosa, renal blood flow and platelet aggregation. The inducible form of COX (COX-2) is responsible for the formation of prostaglandins that pathologically affects inflammation, pain and fever. Clearly, all the experimental and clinical data support the hypothesis that the beneficial effects of NSAIDs are due to inhibition of the COX-2 enzyme, whereas the gastrotoxicity is due to inhibition of COX-1. The cox-2/COX-1 ratios of the NSAIDs in common use have been measured and compared with epidemiological data on their side effects. There is little evidence to suggest that one NSAID is clearly more effective than another, But substantial individual variability is present with respect to the pharmacology and pharmacokinetics of these drugs: therefore it is essential to adjust the dosage and choose specific drug to the patient's response.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.431-435
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• 2014

Zinc peroxide nanoparticles ($ZnO_2$ NPs) were prepared by reacting zinc(II) isobutylcarbamate, as an organometallic precursor, with hydrogen peroxide ($H_2O_2$) at $60^{\circ}C$. Polyethylene glycol and polyvinylpyrrolidone were used as stabilizers, which suppressed aggregation of the $ZnO_2$ NPs. Conditions such as concentrations of $H_2O_2$ and the stabilizer were systemically controlled to determine their effect on the formation of nano-sized $ZnO_2$ NPs. The formation of stable $ZnO_2$ NPs was confirmed by UV-vis, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction. The TEM images revealed that polyvinylpyrrolidone-stabilized $ZnO_2$ NPs (diameter, 10-30 nm) were well dispersed in the organic solvent. Quite pure ZnO NPs were obtained from the peroxide powder by simple heat treatment of $ZnO_2$. The transition temperature of $170^{\circ}C$ was determined by differential scanning calorimetry.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.143-143
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• 2008

Nanowires are promising options for building nanoscale electronic structures coming from high conductivity of nanowires. In particular, Deoxyribonucleic acid (DNA), which is structurally nanowire, can obtain highly ordered electronic components for nanocircuitry and/or nanodevices because of its very flexible length controllability, nanometer-size diameter, about 2 nm, and self-assembling properties. In this work, we used the method to form DNA-Nanowires (NWs) by using chemical treatment on Silicon (Si) surface, and Aminopropyl-triethoxysilane (APTES) was used as inducer of DNA sequence to modify the characteristics of Si surface. Moreover, we performed tilting technique to align DNA by the direction of flow of DNA solution. We investigated the assembly process between DNA molecules and APTES - coated Si surface according to the APTES concentration, from $1.2{\mu}\ell$ to $120{\mu}\ell$. Atomic Force Microscopy (AFM) images showed the combination rate of DNA molecules by the change of APTES concentration. As APTES concentration becomes thicker, aggregation of DNA molecules occurs, and this makes a kind of DNA networks. In this respect, we confirmed that there's a positive relationship between the concentration of APTES and the formation rate of DNA nanowires. Since there have been lots of research preceded to utilize DNA nanowires as template, so by using this positive relationship with proper alignment technique, realization of nano electronic devices with DNA nanowires might be feasible.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1144-1148
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• 2014

Here we report a facile synthesis of ruthenium (Ru) Nanoparticles (NPs) by chemical co-precipitation method. The calcination of ruthenium hydroxide samples at $500^{\circ}C$ under hydrogen atmosphere lead to the formation of $Ru^0$ NPs. The size and aggregation of Ru NPs depends on the pH of the medium, and type of surfactant and its concentration. The X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope image (TEM) analyses of particles indicated the formation of $Ru^0$ NPs, and have 10 to 20 nm sizes. As-synthesized $Ru^0$ NPs are characterized and investigated their catalytic ability in click chemistry (azidealkyne cycloaddition reactions), showing good results in terms of reactivity. Interestingly, small structural differences in triazines influence the catalytic activity of $Ru^0$ nanocatalysts. Click chemistry has recently emerged to become one of the most powerful tools in drug discovery, chemical biology, proteomics, medical sciences and nanotechnology/nanomedicine. In addition, preliminary tests of recycling showed good results with neither loss of activity or significant precipitation.

• 농업과학연구
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• 제41권3호
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• pp.237-243
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• 2014

Human Glucagon like peptide-1 (GLP-1) is an incretin hormone that promotes secretion of insulin. In order to eliminate the formation of the soluble aggregate, Ala19 in GLP-1 was substituted with Thr, resulting in a GLP-1 mutant GLP-1A19T. The gene synthesis of GLP-1A19T and the fusion of 6-lysine tagged ubiquitin gene were accomplished by using the overlap extension polymerase chain reaction. The ubiquitin fused GLP-1A19T (K6UbGLP-1A19T) is expressed as form of inclusion body with little formation of the soluble aggregation in recombinant E. coli. In order to produce K6UbGLP-1A19T in large amounts, fed-batch fermentation was carried out in a pH-stat feeding strategy. Maximum dry cell weight of 87.7 g/L and 20.4% of specific K6UbGLP-1A19T content were obtained. Solid-phase refolding using a cation exchanger was carried out to renature K6UbGLP-1A19T. The refolded K6UbGLP-1A19T aggregated little and was released GLP-1A19T by on-column cleavage with ubiquitin-specific protease-1. The molecular mass of GLP-1A19T showed an accurate agreement with its theoretical molecular mass.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2879-2884
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• 2007

Dynamic responses of electrorheological (ER) fluids in steady pressure flow to stepwise electric field excitations are investigated experimentally. The transient periods under various applied electric fields and flow velocities were determined from the pressure behavior of the ER fluid in the flow channel with two parallel-plate electrodes. The pressure response times were exponentially decreased with the increase of the flow velocity, but increased with the increase of the applied electric field strength. In order to investigate the cluster structure formation of the ER particles, it was verified using the flow visualization technique that the transient response of ER fluids in the flow mode is assigned to the densification process in the competition of the electric field-induced particle attractive interaction forces and the hydrodynamic forces, unlike that in the shear mode determined by the aggregation process.

• 대한화학회지
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• 제38권12호
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• pp.857-863
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• 1994

Sodium dodecyl sulfate (SDS) 존재하에서 유기색소인 thionine (TH)의 흡수 및 형광분광학적 성질을 조사 연구하였다. SDS 농도 증가에 따라 측정한 흡수 및 형광스펙트럼의 변화들로부터 i) TH-SDS 착화합물의 회합체 형성, ii)TH-SDS 회합체내의 색소분자의 stacking 과정, iii)dye-rich induced micelles의 형성에 의한 staking의 파괴 및 iv) SDS 미셀의 표면에 TH의 재분포과정 등으로 설명하였다.

• Food Science and Biotechnology
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• 제17권5호
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• pp.895-898
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• 2008

The mobility of water in set yogurt during fermentation was studied using nuclear magnetic resonance (NMR) relaxometry. The spin-spin relaxation was analyzed using a 2-fraction model, resulting in 2 spin-spin relaxation time constants $T_{21}$ and $T_{22}$. Both $T_{21}$ and $T_{22}$ exhibited rapid changes between 2 and 4 hr of fermentation, coinciding with the drop in pH and the rise in lactic acid bacteria count. The spin-lattice relaxation time $T_1$ increased over the fermentation period. Both $T_1$ and $T_2$ showed an increase in the mobility of water upon gel formation during fermentation. Water redistribution within the gel matrix due to casein aggregation and structure forming may be responsible for the changes in mobility.