• Journal of Microbiology and Biotechnology
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• v.13 no.3
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• pp.360-365
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• 2003

The ability of 19 lactic acid bacteria to produce hydroxy fatty acids (HFAs) from unsaturated food fatty acids (USFAs) was tested. HFAs are related to human ailments, including steatorrhea. All the cultures produced HFAs from USFAs, unless their growth was inhibited by free USFAs. Lactococcus lactis subsp. lactis KFRI 131 converted oleic, linoleic, and linolenic acid into 10-hydroxyoctadecanoic acid (10-HODA), 10-hydroxyoctadecaenoic acid (10-HODEA), and 10-hydroxyoctadecadienoic acid (10-HODDEA), respectively. Both a USFA and a surfactant were needed for the bacterium to convert the fatty acid into the corresponding HFA. It was apparent that the production of 10-HODA was growth-related, while that of 10-HODDEA was not. It was unclear whether the production of 10-HODEA was growth-related.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.27 no.1
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• pp.53-72
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• 2001

Dry skin is caused mainly by the perturbation of stratum corneum lipids which affected by ageing, change of season, excess use of surfactant and the effect of disease like atopic dermatitis and psoriasis. Intercellular lipid structures in stratum corneum are responsible for the barrier function of mammalian skin. The major lipd classes that can be extracted from stratum corneum are ceramides, cholesterol and fatty acid, which make up approximately 50, 25, 10 percent of the stratum corneum lipid mass, respectively. Small amount of cholesterol sulfate, phospholipids, glycosylceramide and cholesterol esters are also present. Recent studies have shown that application of one or two these lipids to the perturbed skin delays barrier recovery; only equimolar mixtures allow normal recovery. We observed that barrier recovery rate was improved in hairless mouse by topical application of single neutral lipids (ceramide, free fatty acid, cholesterol) and lipid mixtures. Whereas the application of single lipid didn’t allows a significant enhancement comparing with normal barrier repair, the equimolar mixtures of 3 components(including synthetic pseudoceramide PC104) improved barrier repair, as assessed by the transepidermal water loss. At clinical study to the volunteers aged over sixty, skin dryness recuperated by the increase of moisture(capacitance) and the reduction of scaling. Utilization of physiologic lipid mixture containing natural ceramides or synthetic pseudoceramide could lead to new forms of topical therapy for the dryness and dermatoses(e.g., psoriasis, atopic dermatitis and irritant dermatitis).

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.51-56
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• 2008

Nonionic sorbitan monostearate have been successfully prepared by esterification using 1,4-sorbitan and stearic acid. 1,4-sorbitan were prepared using D-sorbitol and acid catalyst at solvent-free conditions. The synthesized surfactants were characterized by NMR and FT-IR. We also investigated the effect of temperature, pressure and catalyst on the synthesis of nonionic sorbitan monostearate. The yields of 1,4-sorbitan were 90% at $160^{\circ}C$ under 160 mmHg vacuum, and the yields of nonionic sorbitan monostearate were 92% at $230^{\circ}C$ under 60 mmHg vacuum.

• Journal of the Korean Applied Science and Technology
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• v.18 no.4
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• pp.325-331
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• 2001

The critical micelle concentration (CMC) at which micelles start to form from a surfactant solution is usually measured in terms of conventional concentration units. However, the thermodynamic potentials are expressed in terms of mole fraction $X_{CMC}$ and $X_{CMC}$ cannot be directly measured experimentally. The Gibbs free energy, ${\Delta}G^{\ast}_{mic}$, in particular is related to $X_{CMC}$ through ${\Delta}G^{\ast}_{mic}$ = $RTlnX_{CMC}$. When it comes to CMC, the molar CMC, $C_{CMC}$, differs only by the proportionality $C^{-1}_{w}$ with $C_{w}$ being the molarity of water. Hence, $C_{CMC}$ is found to be a proper representation of CMC. However, in calculation of ${\Delta}G^{\ast}_{mic}$ and other thermodynamic potentials from the CMC, $X_{CMC}$ or $C_{CMC}/C_{w}$ should be used.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1110-1116
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• 2014

The cuprous oxide cubes with the special porous surface constructed by nano-prisms have been successfully fabricated by a solvothermal method. The template-free method is simple and facile without any surfactant. The X-ray powder diffraction (XRD) pattern suggests that the as-prepared product is the pure primitive cubic $Cu_2O$. The effects of the experimental parameters, such as the reaction temperature, reaction time and the concentration of sodium acetate anhydrous, on the morphologies of the products were investigated in detail by the scanning electron microscopy (SEM). Based on the time-dependent experiments, the possible formation mechanism was proposed. Using photocatalytic degrading reactive dyes as the model reaction and xenon lamp to simulate sunlight, the $Cu_2O$ cubes with the porous surface might possess higher photocatalytic activity than those of the commercial $Cu_2O$ powder in the visible-light region, indicating the excellent photocatalytic performance.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.1
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• pp.1-16
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• 2010

The preparation and properties of emulsions stabilized by the adsorption of solid particles at the oil-water interface are reviewed. Comparison is made with the behaviour of surfactant-stabilized emulsions. Many of the properties of Pickering emulsions are attributed to the large free energy of adsorption for particles. The main differences is due to the irreversible adsorption of particles to the interface. Phase inversion from w/o (water-in-oil) to o/w (oil-in-water) can be brought by increasing the volume fraction of water. Hydrophilic particles tend to form o/w emulsion whereas hydrophobic particles form w/o emulsion. The contact angle at the oil-water interface is main parameter to decide the emulsion type. The aspects of stability of Pickering emulsions are in contrast to general emulsions in some points. The possibility using Pickering emulsions for cosmetics is also proposed.

• Elastomers and Composites
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• v.57 no.3
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• pp.100-106
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• 2022

Waterborne polyurethane-acrylate(WPUA) dispersions were prepared by surfactant-free emulsion polymerization in a two-step process. In the first step, polytetrahydrofuran, isophorone diisocyanate, dimethylol proponic acid, and 2-hydroxyethyl methacrylate were used to synthesize a vinyl-terminated polyurethane prepolymer. In the second step, styrene, methyl methacrylate, butyl acrylate, and different multi-functional crosslinkers were copolymerized. 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate were used as the crosslinkers, and their effect on the mechanical and thermal properties of WPUA was investigated. Overall, as the number of functional groups of the cross-linker increased, the gel fraction improved to 79.26%, the particle size increased from 75.9 nm to 148.7 nm, and the tensile strength was improved from 5.86 MPa to 12.40 MPa. In thermal properties, the glass transition temperature and decomposition temperature increased by 9.9℃ and 18℃, respectively. The chemical structures of the WPUA dispersions were characterized by Fourier-transform infrared spectroscopy. The synthesized WPUA has high potential for applications such as coatings, leather coatings, adhesives, and wood finishing.

• Journal of Pharmaceutical Investigation
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• v.38 no.4
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• pp.241-247
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• 2008

Paclitaxel is a taxane diterpene amide, which was first extracted from the stem bark of the western yew, Taxus brevifolia. This natural product has proven to be useful in the treatment of a variety of human neoplastic disorders, including ovarian cancer, breast and lung cancer. Paclitaxel is a highly hydrophobic drug that is poorly soluble in water. It is mainly given by intravenous administration. Therefore, The pharmaceutical formulation of paclitaxel ($Taxol^{(R)}$; Bristol-Myers Squibb) contains 50% $Cremophor^{(R)}$ EL and 50% dehydrated ethanol. However the ethanol/Cremophor EL vehicle required to solubilize paclitaxel in $Taxol^{(R)}$ has a pharmacological and pharmaceutical problems. To overcome these problems, new formulations for paclitaxel that do not require solubilization by $Cremophor^{(R)}$ EL are currently being developed. Therefore this study utilized a supercritical fluid antisolvent (SAS) process for cremophor-free formulation. To select hydrophilic polymers that require solubilization for paclitaxel, we evaluated polymers and the ratio of paclitaxel/polymers. HP-${\beta}$-CD was used as a hydrophilic polymer in the preparation of the paclitaxel solid dispersion. Although solubility of paclitaxel by polymers was increased, physical stability of solution after paclitaxel/polymer powder soluble in saline was unstable. To overcome this problem, we investigated the use of surfactants. At 1/20/40 of paclitaxel/hydrophilic polymer/ surfactant weight ratio, about 10 mg/mL of paclitaxel can be solubilized in this system. Compared with the solubility of paclitaxel in water ($1\;{\mu}g/mL$), the paclitaxel solid dispersion prepared by SAS process increased the solubility of paclitaxel by near 10,000 folds. The physicochemical properties was also evaluated. The particle size distribution, melting point and amophorization and shape of the powder particles were fully characterized by particle size distribution analyzer, DSC, SEM and XRD. In summary, through the SAS process, uniform nano-scale paclitaxel solid dispersion powders were obtained with excellent results compared with $Taxol^{(R)}$ for the physicochemical properties, solubility and pharmacokinetic behavior.

• Journal of Microbiology and Biotechnology
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• v.27 no.12
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• pp.2190-2198
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• 2017

Thermoactinomyces sp. strain YT06 was isolated from poultry compost and observed to degrade integral chicken feathers completely at $60^{\circ}C$, resulting in the formation of 3.24 mg/ml of free amino acids from 50 ml of culture containing 10 g/l chicken feathers. Strain YT06 could grow and secrete keratinase using feather as the only carbon and nitrogen sources without other supplement, but complementation of 10 g/l sucrose and 4 g/l $NaNO_3$ increased the production of the keratinolytic enzyme. The maximum protease activity obtained was 110 U/ml and for keratinase was 42 U/ml. The keratinase maintained active status over a broad pH (pH 8-11) and temperature ($60-75^{\circ}C$). It was inhibited by serine protease inhibitors and most metal ions; however, it could be stimulated by $Mn^{2+}$ and the surfactant Tween-20. A reductive agent (${\beta}$-mercaptoethanol) was observed to cleave the disulfide bond of keratin and improve the access of the enzyme to the keratinaceous substrate. Zymogram analysis showed that strain YT06 primarily secreted keratinase with a molecular mass of approximately 35 kDa. The active band was assessed by MALDI-TOF mass spectrometry and was observed to be completely identical to an alkaline serine protease from Thermoactinomyces sp. Gus2-1. Thermoactinomyces sp. strain YT06 shows great potential as a novel candidate in enzymatic processing of hard-to-degrade proteins into high-value products, such as keratinous wastes.

• Journal of Pharmaceutical Investigation
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• v.36 no.3
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• pp.161-167
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• 2006

The objective of this study was to investigate the dissolution patterns of variety of orally administered drug products available on the market. It aimed to understand their dissolution behaviors on the basis of the biopharmaceutics classification system (BCS) concept. On the tenets of BCS, several active pharmaceutical ingredients were selected: fluoxetine hydrochloride (class I), naproxen sodium (class ll), pyridostigmine bromide (class III), furosemide (class IV) and simvastatin (class IV). Typical dissolution media used in this study were pH 1.2, pH 4 & 6.8 phosphate buffers, and water. In cases, particular dissolution media specified in the KP and/or USP were used. Dissolution patterns of fluoxetine hydrochloride and pyridostigmine bromide products were characterized by their rapid release In addition, their dissolution characteristics were relatively unaffected by the type of a dissolution medium. Similar dissolution patterns were observed with pH 1.2, pH 4 & 6.8 phosphate buffers and water. By sharp contrast, poor dissolution patterns were noticed with naproxen sodium products, when pH 1.2 and pH 4 phosphate buffer were used. Improvements in its dissolution were achieved by switching the dissolution media to pH 6.8 phosphate buffer or water. Unsatisfactory dissolution data also were observed with a simvastatin product, when it was subject to dissolution tests by use of a surfactant-free pH 1.2, pH 4 & 6.8 phosphate buffers and water. All the release patterns reported in this study were best understood when BCS concepts were implemented. Our results demonstrated that a BCS-based drug classification should be considered first to choose a dissolution test/method and set up dissolution specification.