• Journal of the Korean Graphic Arts Communication Society
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• v.21 no.1
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• pp.81-90
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• 2003

To understand the thermoresponsive volume phase transition of an N-isopropyl acrylamide(NIPA) gel on water, the solubility parameter of neutral NIPA gel was determined by swelling the gel with various solvents. Water was found not to be a good solvent for NIPA gel. Equilibrium swelling curves of NIPA gel were respectively obtained by immersing in pure water, ethanol, n-propanol and some mixed solvents. On adding a small amount of alcohols to water, volume phase transition of NIPA gel in water was changed. Phase transition temperature of this gel was decreased with the increase of the carbon number of alcohol.

• The Korean Journal of Mycology
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• v.25 no.2 s.81
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• pp.85-90
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• 1997

The Isozyme activities of Lentinula edodes were studied as a preliminary study for genetic analysis after protoplast fusion. The presence of peroxidase, esterase, superoxide dismutase, acid phosphatase, alkaline phosphatase, alcohol dehydrogenase and ${\alpha}-amylase$ was examined. An intracellular buffer-soluble protein from the mycelia was used for enzyme analysis on nondenaturing polyacrylamide gels. The auxotrophs of Lentinula edodes were positive for peroxidase, esterase, superoxide dismutase and acid phosphatase. However, alkaline phosphatase, alcohol dehydrogenase and ${\alpha}-amylase$ were not detected. The esterase and peroxidase were not affected by the various culture age. Isozyme identification may be a useful tool after protoplast fusion.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.377-382
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• 2011

Poly(vinyl alcohol) (PVA) is an interesting material with good biocompatibility, high elasticity and hydrophilic chacrateristics. In this study, crosslinked hydrogels based on PVA, and poly(acrylic acid) (PAAc) were prepared by gamma-ray irradiation. PVA and PAAc powders were dissolved in deionized water, and then irradiated by a gamma-ray with a radiation dose of 50 kGy to make hydrogels. The hydrogels were then annealed in an oven at $120^{\circ}C$ for 10 min, 30 min and 50 min under nitrogen atmosphere. The properties of a hydrogel such as gel fraction, swelling behavior, thermogravimetric analysis (TGA) and adhesive strength as a function of PAAc content and annealing time were investigated. The gel fraction decreases with decreasing PAAc content and increasing annealing time. The thermal behaviors have shown different patterns according to the annealing time. The adhesive strength increases with increasing PAAc content.

• Transactions on Electrical and Electronic Materials
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• v.4 no.1
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• pp.11-14
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• 2003

The regularities of immobilization of natural medicinal substances - alchidine on gels of poly(vinyl alcohol) - are investigated. It is shown that the polymer components of alchidine interact with nonionic polymer with formation of interpolymer complexes. The influence of the different factors on the properties of complexes is considered and the constants of alchidine distribution in the system gel - water are calculated.

• Journal of the Korean Ceramic Society
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• v.44 no.2 s.297
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• pp.124-131
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• 2007

In this study, first the ADU gel particle, an intermediate for final $UO_2$ kernel of a HTGR nuclear fuel, was prepared from sol-gel method using the broth solution which was made by mixing of the uranyl nitrate, poly vinyl alcohol and tetra-hydrofurfuryl alcohol. The prepared dried-ADU gel particles were converted to the $UO_2\;via\;UO_3$ from thermal treatment with the 4% $H_2$ atmosphere. The sizes of the spherical liquid droplets appeared $1900{\sim}2100{\mu}m$, and the harmony between the flow rate of the broth solution and the frequency and the amplitude of a vibrating system are important factors for the spherical ADU gel particles via the mono size spherical droplets. From the XRD and FT-IR analyses, the prepared ADU gel particles were judged to be a $UO_3{\cdot}xNH_3{\cdot}yH_2O$ form, and the most important factor during the thermal treatment of the dried-ADU gel particle must be avoided a rapidly heating rate in the range of $180{\sim}400^{\circ}C$, and the heating rate should be kept below $5^{\circ}C/min$.

• Polymer(Korea)
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• v.26 no.6
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• pp.792-802
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• 2002

In this study, hydrogels from mixtures of poly (vinyl alcohol) (PVA)/poly(N-vinylpyrrolidone) (PVP)/glycerin/chitosan were prepared by γ-ray irradiation and the mechanical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the applicability of these for wound dressing. Then PVA:PVP was weight ratio of 6 : 4, the concentration of chitosan was 0.3 wt%, the concentration of glycerin was in the range of 0∼5 wt%t. The solid concentration of PVA/PVP/glycerin/chitosan solution was 15 wt%. Gamma irradiation doses of 25, 35, 50, and 60 kGy were exposed to a mixture of PVA/PVP/glycerin/chitosan to evaluate the effect of irradiation dose. Gel content and gel strength increased as glycerin concentration in PVA/PVP/glycerin/chitosan decreased, and as irradiation dose increased. Swelling degree increased as glycerin concentration in PVA/PVP/glycerin/chitosan increased, and as irradiation dose decreased. The glycerin in PVA/PVP/glycerini/chitosan hydrogel prevented the transformation of shape. These hydrogel dressings had better curing effect than vaseline gauge.

• Korean Journal of Materials Research
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• v.33 no.12
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• pp.550-557
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• 2023

In zinc-air batteries, the gel polymer electrolyte (GPE) is an important factor for improving performance. The rigid physical properties of polyvinyl alcohol reduce ionic conductivity, which degrades the performance of the batteries. Zinc acetate is an effective additive that can increase ionic conductivity by weakening the bonding structure of polyvinyl alcohol. In this study, polymer electrolytes were prepared by mixing polyvinyl alcohol and zinc acetate dihydride. The material properties of the prepared polymer electrolytes were analyzed by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Also, Electrochemical impedance spectroscopy was used to calculate ionic conductivity. The electrolyte resistances of GPE, 0.2 GPE, 0.4 GPE, and 0.6 GPE were 0.394, 0.338, 0.290, and 0.213 Ω, respectively. In addition, 0.6 GPE delivered 0.023 S/cm high ionic conductivity. Among all of the polymer electrolytes tested, 0.6 GPE showed enhanced cycle life performance and the highest specific discharge capacity of 11.73 mAh/cm² at 10 mA. These results verified that 0.6 GPE improves the performance of zinc-air batteries.

• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.928-933
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• 2001

Approximately 0.1 mg/ml of polyvinyl alcohol (PVA) was degraded by the growing cell, Brevibacillus laterospours, for 30 h, and 0.2 mg/ml of PVA was degraded by the cell-free extract that was isolated from Brevibacillus laterosporus. Approximately $0.29{\mu}g$/ml of acetic acid was produced from PVA by using the cell-free extract as a catalyst for 40 min. $V_{max}\;and\;K_m$ value of purified PAV-degradation enzyme was 3.75g/l and 2.75 g/l/min in reaction with EDTA and 3.99 g/l and 2.98 g/l/min in reaction without EDTA, respectively. Molecular weight of the purified enzyme determined by SDS-PAGE was 63,000 Da. Alcohol dehydrogenase and aldehyde dehydrogenase activities were qualitatively detected on a native acrylamide gel by an active staining method, indicating the existence of the metabolic pathway to use PVA as a substrate.

• Korean Journal of Pharmacognosy
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• v.29 no.1
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• pp.18-21
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• 1998

A method for isolation and quantitative determination of patchouli alcohol from Pogostemonis Herba (Pogostemon cablin) has been developed. Isolation of patchouli alcohol was achieved by column chromatography employing the normal-phase gradient separation system n-hexane-ether on silica gel column. The GC method for quantitative determination of patchouli alcohol provided a method for standardization of the raw drug. It suggested that the average content of patchouli alcohol in Pogostemonis Herba is about 0.26%.

• Journal of the Korean Ceramic Society
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• v.28 no.5
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• pp.365-372
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• 1991

LAS (lithium aluminosilicate) sol was synthesized using the hydrolysis-condensation reaction of TEOS, chelated Al(OBus)3 and Li-salt with H2O in alcohol (EtOH+2-Propanol) medium. Effects of important reaction parameters on the properties of sol and gel-derived LAS were examined. The crystallization of the sol-gel derived LAS with ${\beta}$-spodumene composition began at ∼600$^{\circ}C$, and a series of polymorphic transformations occurred as temperature was increased to 1100$^{\circ}C$: amorphous LAS\longrightarrowhexagonal LiAl(SiO3)2\longrightarrow${\beta}$-spodumene. Lowering Li content in the gel enhanced densification and retarded the crystallization significantly. Optimum reaction conditions of LAS sol formation for thin coating applications were derived from rheological measurements, and these can be summarized as: H2O/total alkoxides molar ratio=4, pH=∼2.5, and aging time of ∼250h.