• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.112-117
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• 1999

The pulsed field gradient NMR method has been used to determine self-diffusion coefficients in ternary N-alkyl-N, N-dimethylamine oxide/hydrocarbon/$D_2O$ system. For n = 12, 14, 16 and n' = 8, 10, 12, 14, 16, in the micellar phase, diffusion is chiefly governed by the hydrodynamic transport of micelles, supplemented by an exchange of solubilized hydrocarbon upon micellar collisions. This investgation is performed by variations in both the surfactant alkyl chain length and in the size of the hydrocarbon molecules. In cubic phases, the solvent still exhibits values of the diffusion coefficients which are typical for motion in a continuous water phase, with the microemulsion droplets acting as obstacle. Mobilities of the surfactant in the gel state were low and have been determined only for the surfactant($C_{12}DMAO$) with the shortest alkyl chain length. Exchange of hydrocarbon between micellar entities in the gel was found to be occured by a hopping process, the associated rate decreased with alkyl chain length of the surfactant.

• KSBB Journal
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• v.24 no.6
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• pp.533-540
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• 2009

In this work, 5'-nitroindirubinoxime (5'-NIO) has been prepared as solid dispersions using a supercritical aerosol solvent extraction system (ASES) process in order to enhance its water solubility and dissolution rate. Solid dispersions of 5'-NIO and poly(vinyl pyrrolidone) (PVP) were prepared in various weight percent ratios. Three-component solid dispersions consisting of 5'-NIO, PVP, and poloxamer 188 (P188) were also prepared to study the influence of P188 level on their morphology, crystallinity, and dissolution behavior. All samples were prepared at $35^{\circ}C$ and 180 bar using supercritical carbon dioxide. The particle morphology and size of the two-component solid dispersions were found to be nearly spherical and much smaller (100-200 nm) compared with the original 5'-NIO. The morphology of three-component solid dispersions became more agglomerated as the level of P188 increased. The crystallinity of the original 5'-NIO was not observed in the solid dispersions prepared by the ASES process. Faster dissolution rates were observed for the three-componet solid dispersions because the arrangement of ethylene oxide and propylene oxide blocks of the poloxamer 188 enabled the formation of micelles in an aqueous phase.

• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.69-74
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• 2009

Lactic acid bacteria (LAB) were well known to enhance the intestinal health of human. For the development of pharmaceutical LAB. it was screened that the LAB with activity lowering the cholesterol in vitro and evaluated the hypocholestrolemic effect of live and heat-killed (HK) LAB on rats. The selected Lactobacillus plantarum CBT 1209 and Lactobacillus rhamnosus CBT 1702 had the deconjugation of bile salts and assimilation of cholesterol micelles activities from laboratory media, The mixture of 1702 and 1209 strains was administrated to the rats with high cholesterol diet. The experiment performed by 4 groups which were control, HCD, LLAB, HKLAB groups. The hypocholesterolemic effect of LAB (strains 1702, 1209) at blood level, the phenomena of AI decreasing through LDL-cholesterol dwindling, was assessed. This effect of 1702 and 1209 was enhanced when it comes to be the HKLAB more the live-LAB, This data means that the Lactobacillus rhamnosus CBT 1702 and Lactobacillus plantarum CBT 1209 were very useful functional ingredient for hypercholesterolemia.

• Microbiology and Biotechnology Letters
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• v.16 no.3
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• pp.250-258
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• 1988

Lipases are well known as the enzymes which catalyze the hydrolysis of ester bonds combining aliphatic chains and glycerol on mono-, di- and triglycerides. Their reactions are characterized by be-ing heterogeneous and catalyzing the water-insoluble substrates. This property has been one of the Hurdles which delayed the application of lipases in fats and oils industry, However, with the development of biological reaction system of which organic solvent is introduced in part or whole as the reaction media, enzymatic manipulation of fats and oils is attracting increasing attention from the academic and industrial sectors. Trials in two-phase system and reversed micellar system to produce fatty acids through enzymatic hydrolysis of triglycerides preyed to be efficient in respect to volumetric productivity, fat hydrolysis rate, product separation, etc. In organic solvent system lipases have been found to have the ability to catalyze aminolysis, transesterification, esterification, thiotransesterification and oximolysis that are virtually impossible to catalyze in water. The organic solvent system is being extensively used in interesterifying glycerides to produce a fat with the modified physical and chemical nature.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.250-259
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• 2020

The solubilization constant (K_s) was determined by the UV-Vis method to investigate the interaction between organic matter (solubilized substance) and surfactant in solubilization. Solubilization constants and thermodynamic functions, according to the hydrophobic interaction between organic mater (4-alkylanilines with different alkyl substituent length) and cationic surfactants (DTAB, TTAB, and CTAB, having different hydrophobic lengths), were measured and calculated at various temperatures and compared with each other. As a result, the hydrophobic interactions between organic matters and cationic micelles increased with increasing the chain length of solute's substituent as well as surfactant's hydrophobe. However, the hydrophobic effect by the alkyl substituent of organic matter was greater than the hydrophobic effect by the surfactant. In addition, the results of the calculated thermodynamic functions showed that 4-alkylaniline was solubilized at the deep place in the micelle and its solubilization was greatly dependent on both the hydrophobic effects of organic matter and surfactant. At the calculated iso-structural temperature, the difference between the maximum and minimum values was less than 1K within the experimental conditions.

• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.219-225
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• 2014

In this study, effect of cosurfactant on the solubilization rate of n-octane, n-decane and n-dodecane oil was performed by micellar solutions of polymeric nonionic surfactant Pluronic L64($EO_{13}PO_{30}EO_{13}$) at room temperature. It has been found that the solubilization rate of a hydrocarbon oil was enhanced with an increase in both chain length and amount of alcohol added. In case of addition of a short chain alcohol such as 1-butanol, the solubilization rate of a hydrocarbon oil was slightly increased since most of alcohol molecules remained in an aqueous surfactant solution. On the other hand, the addition of a relatively long chain alcohol such as 1-hexanol and 1-octanol produced a big increase in solubilization rate of a hydrocarbon oil mainly due to incorporation of alcohol molecules into micelles and thus producing more flexible micellar packing density. Dynamic interfacial tension measurements showed the same trend found in solubilization rate measurement. Both interfacial tension value at equilibrium and time required to reach equilibrium decreased with an increase in chain length of an alcohol.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.195-202
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• 2004

Micellar catalysis is an essential part of theoretical and experimental curricular. The sodium dodecylsulfate (SDS) catalyzed reaction between glycine and potassium permanganate in acidic medium is an ideal kinetic experiment for the secondary and undergraduate physical chemistry laboratory, to show the effect of micellar catalysis on rate of the reaction. The reaction is conducted both with and without SDS to observe the rate enhancement in the presence of surfactant. To show surfactant catalysis a plot between k and [SDS] is plotted. As surfactant catalysis is observed even before the critical micelle concentration of SDS, this pre-micellar catalysis can be understood in the light of positive co-operativity. The value of positive cooperative index (n) has been found to be 2.37. Further, dependence of the reaction rate on substrate and oxidant concentrations is also discussed. The reaction follows pseudo-first-order kinetics. The overall reaction is second order, with first-order dependence on both glycine and permanganate concentrations. The theory of surfactant catalysis is also discussed. With the conditions specified in the experiment, total reaction times are in 3~4 hours lab session, thus allowing several data sets to be acquired in a single laboratory period. Preparation of solutions and procedure is also given in detail.

• Journal of Environmental Science International
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• v.21 no.5
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• pp.585-596
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• 2012

This study is mainly focused on micellar effect of cetyltrimethyl ammonium bromide(CTABr) solution including alkylbenzimidazole(R-BI) on dephosphorylation of isopropyl-4-nitrophenylphosphinate(IPNPIN) in carbonate buffer(pH 10.7). The reactions of IPNPIN with R-$BI^{\ominus}$ are strongly catalyzed by the micelles of CTABr. Dephosphorylation of IPNPIN is accelerated by $BI^{\ominus}$ ion in $10^{-2}$ M carbonate buffer(pH 10.7) of $4{\times}10^{-3}$ M CTABr solution up to 89 times as compared with the reaction in carbonate buffer by no benzimidazole(BI) solution of $4{\times}10^{-3}$ M CTABr. The value of pseudo first order rate constant($k_{\Psi}$) of the reaction in CTABr solution reached a maximum rate constant increasing micelle concentration. Such rate maxima are typical of micellar catalyzed bimolecular reactions. The reaction mediated by R-$BI^{\ominus}$ in micellar solutions are obviously slower than those by $BI^{\ominus}$, and the reaction rate were decreased with increase of lengths of alkyl groups. It seems due to steric effect of alkyl groups of R-$BI^{\ominus}$ in Stern layer of micellar solution. The surfactant reagent, CTABr, strongly catalyzes the reaction of IPNPIN with R-BI and its anion(R-$BI^{\ominus}$) in carbonate buffer(pH 10.7). For example, $4{\times}10^{-3}$ M CTABr in $1{\times}10^{-4}$ M BI solution increase the rate constant($k_{\Psi}=98.5{\times}10^{-3}\;sec^{-1}$) of the dephosphorylation by a factor ca.25, when compared with reaction($k_{\Psi}=3.9{\times}10^{-4}\;sec^{-1}$) in $1{\times}10^{-4}$ M BI solution(without CTABr). And no CTABr solution, in $1{\times}10^{-4}$ M BI solution increase the rate constant($k_{\Psi}=3.9{\times}10^{-4}\;sec^{-1}$) of the dephosphorylation by a factor ca.39, when compared with reaction ($k_{\Psi}=1.0{\times}10^{-5}\;sec^{-1}$) in water solution(without BI). This predicts that the reactivities of R-$BI^{\ominus}$ in the micellar pseudophase are much smaller than that of $BI^{\ominus}$. Due to the hydrophobicity and steric effect of alkyl group substituents, these groups would penetrate into the core of the micelle for stabilization by van der Waals interaction with long alkyl groups of CTABr.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.46-53
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• 2009

Phase equilibrium and dynamic behavior studies were performed in systems containing $C_{12}E_5$ nonionic surfactant solution and nonpolar hydrocarbon oil. The phase behavior result showed an oil-in-water(O/W) microemulsion(${\mu}E$) in equilibrium with excess oil phase at low temperatures and a water-in-oil(W/O) ${\mu}E$ in equilibrium with excess water phase at high temperatures. For intermediate temperatures a 3 phase region containing excess water, excess oil, and a middle-phase microemulsion was observed and the transition temperature was found to increase with an increase in the chain length of a hydrocarbon oil. Dynamic behavior at low temperatures showed that an oil drop size decreased linearly with time due to solubilization into micelles and the solubilization rate decreased with an increase in the chain length of a hydrocarbon oil. On the other hand, both spontaneous emulsification of water into oil phase and expansion of oil drop with time were observed because of diffusion of surfactant and water into oil phase. Under conditions of a 3 phase region including a middle-phase ${\mu}E$, both rapid solubilization and emulsification of oil into aqueous surfactant solution were found mainly due to the existence of ultra-low interfacial tension. Interfacial tensions were measured as a function of time for n-decane oil drops brought into contact with 1 wt% surfactant solution at $25^{\circ}C$. Both equilibrium interfacial tension and equilibration time were found to increase with an increase in the chain length of a hydrocarbon oil.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.473-478
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• 2009

Phase equilibrium and dynamic behavior studies were performed on systems containing $C_{10}E_5$ nonionic surfactant solutions and nonpolar hydrocarbon oils. The phase behavior showed an oil in water (O/W) microemulsion (${\mu}E$) in equilibrium with excess oil phase at low temperatures and a water in oil (W/O) ${\mu}E$ in equilibrium with excess water phase at high temperatures. For intermediate temperatures a three-phase region containing excess water, excess oil, and a middle-phase microemulsion was observed and the transition temperature was found to increase with an increase in the chain length of a hydrocarbon oil. Dynamic behavior at low temperatures showed that an oil drop size decreased linearly with time due to solubilization into micelles and the solubilization rate decreased with an increase in the chain length of a hydrocarbon oil. On the other hand, both spontaneous emulsification of water into oil phase and expansion of oil drop were observed because of diffusion of surfactant and water into oil phase. Under conditions of a 3 phase region including a middle-phase ${\mu}E$, both rapid solubilization and emulsification of oil into aqueous solutions were found mainly due to the existence of ultra-low interfacial tension. Interfacial tensions were measured as a function of time for n-decane oil drops brought into contact with 1 wt% surfactant solution at $25^{\circ}C$. Both equilibrium interfacial tension and equilibration time increased with an increase in the chain length of a hydrocarbon oil.