• Asian-Australasian Journal of Animal Sciences
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• 제28권3호
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• pp.420-427
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• 2015

It is necessary to understand the cellular uptake and cytotoxicity of food-grade delivery systems, such as ${\beta}$-lactoglobulin (${\beta}$-lg) nanoparticles, for the application of bioactive compounds to functional foods. The objectives of this study were to investigate the relationships between the physicochemical properties of ${\beta}$-lg nanoparticles, such as particle size and zeta-potential value, and their cellular uptakes and cytotoxicity in Caco-2 cells. Physicochemical properties of ${\beta}$-lg nanoparticles were evaluated using particle size analyzer. Flow cytometry and confocal laser scanning microscopy were used to investigate cellular uptake and cytotoxicity of ${\beta}$-lg nanoparticles. The ${\beta}$-lg nanoparticles with various particle sizes (98 to 192 nm) and zeta-potential values (-14.8 to -17.6 mV) were successfully formed. A decrease in heating temperature from $70^{\circ}C$ to $60^{\circ}C$ resulted in a decrease in the particle size and an increase in the zeta-potential value of ${\beta}$-lg nanoparticles. Non-cytotoxicity was observed in Caco-2 cells treated with ${\beta}$-lg nanoparticles. There was an increase in cellular uptake of ${\beta}$-lg nanoparticles with a decrease in particle size and an increase in zeta-potential value. Cellular uptake ${\beta}$-lg nanoparticles was negatively correlated with particle size and positively correlated with zeta-potential value. Therefore, these results suggest that the particle size and zeta-potential value of ${\beta}$-lg nanoparticles play an important role in the cellular uptake. The ${\beta}$-lg nanoparticles can be used as a delivery system in foods due to its high cellular uptake and non-cytotoxicity.

• Tribology and Lubricants
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• 제33권5호
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• pp.228-233
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• 2017

Chemical Mechanical Polishing of chemically stable sapphire substrates is dominantly affected by the mechanical processing of abrasives, in terms of the material removal rate. In this study, we investigated the effect of electrostatic force between the abrasives and substrate, on the polishing. If potassium chloride (KCl) is added to slurry, water molecules are decomposed into $H^+$ and $OH^-$ ions, and the amount of ions in the slurry changes. The zeta potential of the abrasives decreases with an increase in the amount of $H^+$ ions in the stern layer; consequently, the electrostatic force between the abrasives and substrate decreases. The change in zeta potential of abrasives in the slurry is affected by the slurry pH. In acidic zones, the amount of ions bound to the abrasives increases if the amount of $H^+$ ions is increased by adding KCl. However, in basic zones, there is no change in the corresponding amount. In acidic zones, zeta potential decreases as molar concentration of potassium increases; however, it does not change significantly in basic zones. The removal rate tends to decrease with increase in molar amount of potassium in acidic zones, where zeta potential changes significantly. However, in basic zones, the removal rate does not change with zeta potential. The tendencies of zeta potential and that of the frictional force generated during polishing show strong correlation. Through experiments, it is confirmed that the contact probability of abrasives changes according to the electrostatic force generated between the abrasives and substrate, and variation in removal rate.

• 한국미생물·생명공학회지
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• 제42권2호
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• pp.114-120
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• 2014

본 연구에서는 주목 식물세포(Taxus chinensis) 배양 유래항암물질 paclitaxel을 정제하기 위하여, 반응액 부피당 표면적이 증가된 분별침전에서 표면적증가물질 실리카-알루미나의 제타전위가 분별침전 양상(순도, 수율, 침전시간, 침전물형태와 크기)에 미치는 영향을 조사하였다. 실리카-알루미나의 제타전위가 양(+)의 값으로 증가할수록 paclitaxel 수율은 증가하였으며 침전 시간은 감소하였다. 표면적증가물질로 제타전위가 가장 큰 알루미나(제타전위: +35.41 mV)를 이용한 경우 표면적증가물질을 이용하지 않은 경우에 비해 침전에 소요되는 시간을 12시간 정도 단축시킬 수 있었다. 반면 표면적증가물질 실리카-알루미나의 전타전위 변화에도 paclitaxel 순도는 거의 변화가 없었다. 또한 분별침전 과정에서 제타전위 절대값이 증가할수록 paclitaxel 침전물의 크기는 감소하여 제타전위 절대값에 반비례함을 알 수 있었다. 이러한 개선된 분별침전 공정은 바이오매스 유래 paclitaxel 정제 공정에 효과적으로 기여할 것으로 판단된다.

• 대한화장품학회지
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• 제33권2호
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• pp.105-110
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• 2007

제타전위를 이용하여 이산화티탄의 분산 안정성을 평가하고 이를 통하여 분산안정도 향상에 응용하고자 하였다. 본 연구에서는 제타전위와 관련된 전기이중층, 전기영동, 등전점 및 전기 침투에 대하여 설명하였으며 측정이론을 기술하였다. H-S equation을 이용하여 수계에 분산된 미립자 이산화티탄의 pH변화에 따른 제타전위 변화를 측정하였으며 제타전위는 pH $3.0{\sim}9.0$에서 음의 값으로 측정되었다. 제타전위 값은 pH값 상승에 따라 절대값이 증가하였으며 분산액의 pH 8.0과 9.0에서는 지속적으로 분산이 유지되었다. 이를 통하여 제타전위가 이산화티탄의 분산에 영향을 미치며 제타전위의 절대값 크기가 수계에서 이산화티탄의 분산안정도에 중요한 역할을 하는 것으로 생각된다.

• Korean Journal of Mathematics
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• 제19권2호
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• pp.129-147
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• 2011

In this paper we discuss the zeta-determinants of harmonic oscillators having general quadratic potentials defined on $\mathbb{R}^2$. By using change of variables we reduce the harmonic oscillators having general quadratic potentials to the standard harmonic oscillators and compute their spectra and eigenfunctions. We then discuss their zeta functions and zeta-determinants. In some special cases we compute the zeta-determinants of harmonic oscillators concretely by using the Riemann zeta function, Hurwitz zeta function and Gamma function.

• 한국결정성장학회지
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• 제15권6호
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• pp.239-243
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• 2005

The effect of pH and particle size on the dispersion stability of ultra-fine $BaTiO_3$ suspensions in aqueous medium have been investigated by means of zeta potential, sediment experiments, and powder properties (particle analysis, specific surface area) etc. Zeta potential as a function of pH for two particles of different size increases from -75 to +10 mV with decreasing pH from 8.5 to 1.4. The curve of zeta potential for small particle (150 nm) has slow slope than that of large particle (900nm), giving IEP (isoelectric point) value of pH=1.6 for small particle and pH=1.9 for large particle respectively, which means that it is more difficult to control zeta potential with pH fur small particle than large particle. The dispersion stability of $BaTiO_3$ particles in aqueous medium was found to be strongly related with the agglomeration of colloidal suspensions with time through the sedimentation behaviors of colloidal particles with time and pH value.

• 멤브레인
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• 제27권5호
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• pp.399-405
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• 2017

계면동전위라 불리는 제타전위(zeta potential)란 표면 전하적 특성을 정량화 한 값으로 전기동역학적 현상으로 발생하는 전위차를 말한다. 제타전위는 막오염(fouling)과 표면전하 분석을 통한 개질 확인 및 치환기 확인에 대한 연구가 활발히 진행되어 왔다. 그리고 제타전위를 측정하는 방법으로는 전기영동(electrophoresis), 전기삼투(eletrosmosis), 유동전위(streaming potential)를 기초로 개발되었고, 그중에서도 평막은 유동전위 측정이 적합하다고 알려졌다. 따라서, 본 연구에서는 poly(styrene-ethylene-butylene-styrene) 고분자에 암모늄을 도입하여 아민화된 SEBS 평막 형택의 분리막을 제조하고, 계면동전위 측정기를 이용하여 제조된 분리막들의 유동전위를 측정하여 결과를 분석하였다.

• Carbon letters
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• 제8권4호
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• pp.321-325
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• 2007

The oxygen and nitrogen enriched activated carbons were obtained from modification of commercial activated carbon by using nitric acid, sodium hydroxide and urea. Zeta-potentials of modified activated carbons were investigated in relation to copper ion adsorption. The structural properties of modified activated carbons were not so much changed, but the zeta-potentials and isoelectric points were considerably changed. The zeta-potential of nitric acid modified activated carbon was the most negative than other activated carbons in the entire pH region, and the $pH_{IEP}$ was shifted from pH 4.8 to 2.6, resulted in the largest copper ion adsorption capacities compare with other activated carbons in the range of pH 3~6.5. In case of urea modified activated carbon, copper ion adsorption was larger than that of the as-received activated carbon from pH 2 to pH 6.5 even though the $pH_{IEP}$ was shifted to pH 6.0, it was due to the coordination process operated between nitrogen functional groups and copper ion. The adsorption capacity of copper ion was much influenced by zeta-potential and $pH_{IEP}$ of carbon adsorbent.

• Journal of Forest and Environmental Science
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• 제22권1호
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• pp.27-31
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• 2006

본 연구에서는 재생지를 원료로 하여 화장지를 만드는 제지공장의 원폐수를 사용하였으며, 폐수처리의 기초적 전처리 방법으로 zeta potential을 측정 (원성연, 1995 : 이학래등, 1996) 하여 적정 응집제 투입량을 선정하고, 응집제를 투입량에 따른 탁도 (Turbidity), 총고형물 (suspended solids : SS), 화학적 산소요구량 (chemical oxygen demand : COD)을 측정하여 최적 응집제 투입량을 검토하였다. 또한 응집 침전의 효율을 결정하는 가장 중요한 평가항목인 floc의 기계적 강도(임호주, 2002)를 측정해 봄으로써 기계적 강도가 양호하면서 응집효과가 좋은 최적 조건을 검토하였다. 따라서 최적 응집제 투입량에 따른 응집제의 사용량 감소에 의한 실제 공장에서 약품비용의 절감 효과와 폐수처리 효율의 극대화를 기대 할 수가 있다고 사료된다.

• 대한화장품학회지
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• 제23권1호
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• pp.145-158
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• 1997

Lipid를 이용하여 보다 안정한 microemulsion을 제조함에 있어 Zeta potential을 이요하여 비교 분석 하여 보았다. 실험 시 Lipid Base와 Cetyl phosphate의 함량변화가 particle size와 zeta potential에 미치는 영향에 대하여 실험을 수행하였으며, zeta potetial의 시간 경과에 따른 경시변황 대하뎌도 조사하여 microemulsion의 적정조건을 찾을 수 있었다. microemulsion과 emulsion에 대하여 안전성을 비교 관찰 하였다.