• Applied Biological Chemistry
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• v.27 no.2
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• pp.112-118
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• 1984

Inverase was entrapped in calcium alginate gel. The immobilized beads had excellent uniform size and configuration. To screen the optimal conditions possessing high enzyme activity, effects of sodium alginate concentration, $CaCl_2$ concentration, and the incubation time of beads in $CaCl_2$ solution during the immobilization procedure were investigated. Immobilized beads prepared from the optimal conditions had 18.8 units per ml of gel, which is equivalent to 68% of the activity of soluble enzyme. Several kinetic parameters were determined: Km value. 143 mM; optimum pH, 4.5; optimum temperature, $50^{\circ}C$. Enzyme loading capacity was 150 mg per 20 ml gel. No significant decrease in sugar conversion was observed during the column operation for 6 days.

• Polymer(Korea)
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• v.36 no.5
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• pp.617-621
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• 2012

PHEAs [${\alpha}$,${\beta}$-poly(2-hydroxyethyl-DL-aspartamides)], a class of poly(amino acid), have been widely studied as biodegradable and biocompatible polymers for potential biomedical and pharmaceutical applications. In this study, we investigated a homogeneous blend of PHEA with poly(N-vinyl pyrrolidone) (PNVP) and its semi-IPN (semi-interpenetrating polymer network) gels. Blend films were prepared by a solution casting method. The resulting blends were totally transparent over the whole composition ranges and the single $T_g$, changing monotonously with composition, was observed by DSC to confirm the miscibility between these two polymers. FTIR was used to discuss the possible hydrogen-bonding interaction between polymers. In addition, semi-IPN type gels were prepared by chemical crosslinking of PHEA/PNVP blend solution using hexamethylene diisocyanate (HMDI) as a crosslinking reagent. The prepared gel was characterized by their swelling property and morphology.

• Journal of Digital Convergence
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• v.14 no.3
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• pp.437-443
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• 2016

To treat a kind of nail damage, this study proceeded with gel polish procedure oriented to 19 women in their twenties and thirties, dividing into three experimental groups, such as the A group with non-treatment (n=6), the B group taking Nutritional Convergent supplement (n=6), and the C group simultaneously taking Nutritional Convergent supplement and Nail Convergent Strengthener (n=7), and inquired into the superficial change of nails, changes of thickness, analysis of damage degree and satisfaction rate. The analysis shows that the C group simultaneously applied with dietary supplement and complex nail supplement presented the best result in all areas. As for the morphological changes of the surface of nails measured by the scanning electron microscope, there were definite changes as compared with the B group. According to the result, it is proved that complex dietary supplement helps to improve the thickness and the surface of damaged nails and it is reasoned that a higher effect can be expected when complex nail supplement is simultaneously used.

• Polymer(Korea)
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• v.27 no.6
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• pp.555-561
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• 2003

The self-assembled monolayer coating of octadecyltrichlorosilane (OTS) on the silicon based MEMS was investigated and surface characteristics were considered as a function of coating conditions and reagent composition. The sulfuric peroxide mixture (SPM) solution was used to form -OH group which caused the hydrophilic characteristic on silicon surftce. Highest hydrophilicity was obtained by SPM solution with 85% acid content at room temperature. OTS was applied on the silicon surface by means of self-assembled monolayers (SAMs) coating. It was found that sol-gel reaction was took place between -OH group on the silicon surface and -Cl group in OTS. As a result, the contact angle increased due to the increase of hydrophobicity by Si-O bonding of SAMs. Sol-gel reaction could be controlled by coating conditions as well as reagent composition in OTS coating solution.

• Polymer(Korea)
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• v.37 no.5
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• pp.553-556
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• 2013

Chlorine dioxide gas has an excellent ability for sterilization and deodorization, and is harmless to humans. However, it is very unstable and explosive as it is highly concentrated, thus its use in the air clean fields has been limited. Therefore, there is need to control chlorine dioxide gas at a low concentration for a long time. Chlorine dioxide gas could be produced slowly and sustainedly since the release of acetic acid from the polymer hydrogels delayed the reaction between acetic acid and sodium chlorite. In addition, as the amount of both acetic acid sodium chlorite loaded within the hydrogel and on the membrane increased, respectively, the generation amount of chlorine dioxide gas increased. The result shows that the use of polymer hydrogels has the potential to control the generation of chlorine dioxide gas.

• Polymer(Korea)
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• v.33 no.1
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• pp.1-6
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• 2009

We report the template-based synthesis of well-dispersed CdS nanoparticles (NPs) in the interior of poly (2-acetamidoacrylic acid) (PAAA) hydrogel as a novel type of nanocomposite without particle aggregation via ion exchange in a aqueous system. As revealed by the TEM image analysis, the mean crystallite diameter of CdS NPs embedded in hydrogel composite was 4.5 nm, and the composite did not suffer any observable change after 6 months. Desorption/decomposition of CdS/PAAA hydrogel composite was studied by evolved gas analysis-gas chromatography-mass spectrometry (EGA-GC-MS), and thermogravimetric analysis (TGA) methods. From the TGA data, the thermal stability of the composite system increased by ca. 100 $^\circ$C and the content of CdS NPs in a dry composite gel was over 70 wt%. In addition, the chemical pathway was proposed for the entire decomposition process.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.5
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• pp.10-17
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• 2021

In this study, cold-flow test of simulant gel is conducted using a pressure swirl injector to identify spray characteristics according to gellant weight percent. Experiment results show the aircore is developed locally at the nozzle and expanded to the entire swirl chamber as the supply pressure increases. The aircore formation of simulant gel showed no significant difference compared to Newtonian fluid. The spray pattern was classified into four distinct shapes where relationship between the breakup regimes and dimensionless numbers were investigated. In the future, additional study is necessary to understand the aircore formation mechanism, stability and spray characteristics at different configuration of the swirl chamber shape.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.5
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• pp.73-79
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• 2021

This study was carried out to analyze the properties of the gel propellant and spray characteristics according to the addition of fine particles. The multi-hole diameter was 0.4 mm to induce a high shear rate, and a kerosene gel propellant was prepared using 5 wt% of the Thixatrol ST and SUS304 of 100 nm. The experiment was conducted by fixing the supply pressure in the axial direction to 0.7 MPa and adjusting the supply pressure in the radial direction from 0.7 MPa to 2.1 MPa. Due to the addition of fine particles, pressure vibration during spraying, a small TMR(Total Momentum Ratio) of up to 0.19, and a phenomenon that the spraying angle rapidly increased to more than 70 degrees occurred.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.210-215
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• 2022

Two types of lignin materials with a different surface ionic character were used and polypyrrole layer was introduced on the lignin surface to obtain polypyrrole@lignin and polypyrrole@lignosulfonate composites using a simple chemical oxidation polymerization, reported in a previous article. Polypyrrole was effectively prepared regardless of the lignin type and the resulting composites were investigated using scanning electron microscope (SEM), cyclic voltammetry (CV), and impedance analysis. SEM and CV results showed that the obtained composites retained stable electrochemical properties after introduction of polypyrrole on the lignin surface. Impedance analyses showed that the surface properties of composites were dependent on lignin characteristics. In addition, the composites were embedded in agarose, an gelifying agent, to obtain conductive gels. It was found that the conductive gels possessed an electrical conductivity and also retained stable electrochemical properties, which indicated that the conductive gels might be useful for some applications.

• Microbiology and Biotechnology Letters
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• v.15 no.2
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• pp.122-128
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• 1987

Lipases from Candida rogosa and Rhizopus arrhizus were immobilized by entrapment with photo-crosslinkable resin prepolymer for the study of fat splitting and interesterification in isooctane-two phase system. Dioctylsulfosuccinate was selected as the most suitable surfactant during the immobilization. Lipase entrapped with hydrophobic photo-crosslinkable resin prepolymer(ENTP-3000) exhibited the highest activity, whereas lipase entrapped with hydrophilic gel(ENT-4000) was more stable in organic solvent. As the degree of hydrophobicity of the immobilization matrix was increased, Vm(app) of the lipase entrapped was increased, but Km(app) was approximately constant. While the optimum pH of the lipases entrapped on hydrophilic gel (ENT-4000) were around pH 7.0 for Candida lipase and Rhizopus lipase, the reaction rate of the lipases entrapped on hydrophobic gel were less dependent on pH variations for short reaction time. However, for longer reaction time, the lipnses from C. rugosa and R. arrhizus entrapped on hydrophobic gel yielded maximum rate at pH 6.0 and 6.5, respectively, Entrapment method endowed the lipase with thermal stability.