• Polymer(Korea)
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• v.30 no.5
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• pp.380-384
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• 2006

Polyhedral oligomeric silsesquioxanes (POSS) were used as starting materials for the preparation of hybrid materials with polystyrene (PS). Optically transparent hybrids were obtained in a wide range of weight ratios when phenyl groups were introduced to each corner of the silsesquioxane. In contrast, as cyclohexyl groups were introduced, the obtained hybrid materials with PS resulted in turbid films. The aromatic (${\pi}-{\pi}$) interaction was confirmed to be a quite effective tool for the synthesis of organic-Inorganic polymer hybrids with POSS. The obtained homogeneous and transparent hybrid films could be dissolved in solvents and East again without any separation. The homogeneity of polymer hybrids with POSS was supported by the result of scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), which demonstrated a nanometer-level integration of PS and POSS.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.07a
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• pp.11-15
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• 1999

In order to evlauate feasibility of the gene tagging by the maize transposable element Ac in heterologous plant systems, we have investigated physical distances and directions of transposition of the element in Arabidopsis thaliana and tobacco cultured cell line BY-2. We prepared a T-DNA construct that carried a non-autonomous derivative of Ac with a site for cleavage by endonuclease I-Scel (designated dAc-I-RS element). Another cleavage site was also introduced into the T-DNA region outside dAc-I-RS. A number of transgenic Arabidopsis plants were generated, each of which had a single copy of the T-DNA at a different chromosomal location. To examine the pattern of transposition, three out of these transgenic plants were crossed with the Arabidopsis plant that carried the gene for Ac transposase and progeny in which dAc-I-RS had been transposed were isolated. After digestion of the genomic DNA of these progeny with I-SceI, sizes of segment of DNA were determined byd pulse-field gel electrophoresis. We also performed linkage analysis for the transposed elements and sites of mutations near the elements. Our results with three transgenic lines showed that 50% of all transposition events had occurred within 1,700 kilo-base pairs (kb) on the same chromosome, with 35% within 200 kb, and that the elements transposed in both directions on the chromosome with roughly equal probability. The data thus indicate that the Ac-Ds system is most useful for tagging of genes that are present within 200 kb of the chromosomal site of Ac in Arabidopsis. In addition, determination of the precise localization of the transposed dAc-I-RS element should definitely assist in map-based cloning of genes around insertion sites. In the present paper, we report typical examples of such gene isolation studies.

• Proceedings of the Botanical Society of Korea Conference
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• 1985.08b
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• pp.51-57
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• 1985

In order to evlauate feasibility of the gene tagging by the maize transposable element Ac in heterologous plant systems, we have investigated physical distances and directions of transposition of the element in Arabidopsis thaliana and tobacco cultured cell line BY-2. We prepared a T-DNA construct that carried a non-autonomous derivative of Ac with a site for cleavage by endonuclease I-Scel (designated dAc-I-RS element). Another cleavage site was also introduced into the T-DNA region outside dAc-I-RS. A number of transgenic Arabidopsis plants were generated, each of which had a single copy of the T-DNA at a different chromosomal location. To examine the pattern of transposition, three out of these transgenic plants were crossed with the Arabidopsis plant that carried the gene for Ac transposase and progeny in which dAc-I-RS had been transposed were isolated. After digestion of the genomic DNA of these progeny with I-SceI, sizes of segment of DNA were determined byd pulse-field gel electrophoresis. We also performed linkage analysis for the transposed elements and sites of mutations near the elements. Our results with three transgenic lines showed that 50% of all transposition events had occurred within 1, 700 kilo-base pairs (kb) on the same chromosome, with 35% within 200 kb, and that the elements transposed in both directions on the chromosome with roughly equal probability. The data thus indicate that the Ac-Ds system is most useful for tagging of genes that are present within 200 kb of the chromosomal site of Ac in Arabidopsis. In addition, determination of the precise localization of the transposed dAc-I-RS element should definitely assist in map-based cloning of genes around insertion sites. In the present paper, we report typical examples of such gene isolation studies.

• Polymer(Korea)
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• v.27 no.6
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• pp.542-548
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• 2003

Nanoparticles with unsaturated poly(hydroxyalkanoate)s (UPHAs) biosynthesized with Pseudo-monas oleovorans were prepared by spontaneous emulsification solvent diffusion method. The influence of nanoparticle formation was investigated with various experimental parameters such as sonication conditions, sol-vent, surfactant and polymer contents, etc. The physical and chemical properties of UPHAS and its nanoparticles were characterized using $^1$H- and $\^$13/C-nuclear magnetic resonance spectroscopies, attenuated total reflection infrared spectroscopy, differential scanning calorimetry and gel permeation chromatography. The morphology of particles was observed using scanning electron microscope and the size and distribution of nanoparticles were measured with electrophoretic light scattering spectrophotometer. The mean diameter of particles decreased with increasing sonication amplitude and time. The addition of ethanol into UPHAS chloroform solution decreased the particle size presumably due to increased solvent diffusion into water phase. The particle size increased with increased the concentration of UPHAS solution. Under the 2-4％ poly(vinyl alcohol) (PVA) aqueous solution the minimum mean diameter of particles was shown. The higher degree of hydrolysis and degree of polymerization of PVA increased the mean diameter of particles.

• Fisheries and Aquatic Sciences
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• v.13 no.1
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• pp.1-11
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• 2010

The study was performed to optimize the processing conditions (alkali concentration, extraction time, and temperature) for rockfish skin gelatin based on yield using response surface methodology and comparison of the physicochemical properties with those of rockfish skin gelatin pretreated and extracted under ordinary conditions (alkali treatment concentration: 1.0 M; extraction time: 2 hr; extraction temperature: $60^{\circ}C$). Predicted maximum gelatin yield of 19.1% and gelatin content of 87.8% were obtained by extraction at $106.6^{\circ}C$ for 69.0 min after pretreatment with 1.1 M calcium hydroxide. Yield of gelatin extracted under high temperature/high pressure (G-HT/HP) was 54% higher than that extracted under ordinary temperature/time (G-OT/T). However, G-HT/HP was inferior in gel strength and gelling point to (G-OT/T), but comparable in transmission. Based on the physicochemical properties, G-HT/HP was unsuitable for use in products requiring higher physical properties, but could be useful for health-functional foods.

• Journal of Ecology and Environment
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• v.41 no.9
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• pp.235-245
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• 2017

Background: Loading of excess nutrient via bioremediation of polluted sediment to overlying water could trigger anoxia and eutrophication in coastal area. The aim of this research was to understand the changes of overlying water features such as dissolved oxygen (DO); pH; oxidation reduction potential (ORP); $chlorophyll-{\alpha}$ ($Chl-{\alpha}$); and nitrogen nutrients ammonia ($N-NH_4{^+}$), nitrate ($N-NO_3{^-}$), and nitrite ($N-NO_2^-$) when the sediment was not treated (control) and treated by calcium peroxide for 5 weeks. Methods: The water samples were analyzed for measuring physical and chemical properties along with the sediment analyzed by polymerase chain reaction (PCR) including denaturing gradient gel electrophoresis (DGGE) for identifying the phylogenetic affiliation of microbial communities. Results: Results showed that due to the addition of calcium peroxide in sediment, the overlying water exposed the rise of dissolve oxygen, pH, and ORP than control. Among the nitrogen nutrients, ammonia inhibition was higher in calcium peroxide treatment than control but in case of nitrate inhibition, it was reversed than control. $Chlorophyll-{\alpha}$ was declined in treatment column water by 30% where it was 20% in control column water. Actibacter and Salegentibacter group were detectable in the calcium-peroxide-treated sediment; in contrary, no detectable community ware found in control sediment. Both phylogenetic groups are closely related to marine microflora. Conclusions: This study emphasizes the importance of calcium peroxide as an oxygen release material. Interaction with peroxide proved to be enhancing the formation of microbial community that are beneficial for biodegradation and spontaneity of nutrient attenuation into overlying water.

• The korean journal of orthodontics
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• v.46 no.3
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• pp.146-154
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• 2016

Objective: Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of $TiO_2$ on organic compounds, we hoped to synthesize a novel bracket with a $TiO_2$ thin film to develop a photocatalytic antimicrobial effect. Methods: The sol-gel dip coating method was used to prepare $TiO_2$ thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. Results: Films with 5 coating layers annealed at $700^{\circ}C$ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. $TiO_2$ thin films with 5 coating layers annealed at $700^{\circ}C$ exhibited the greatest antimicrobial activity under UV-A light irradiation. Conclusions: These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.271-278
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• 2006

We used polymers of alternating cationic and anionic nature to build up shells on fiber surfaces, strengthen the worn-out fibers and improve paper properties made from such fibers. OCC and ONP pulps were either dipped or salted out in the cationic polyallylamine, polyacrylamide and starch solutions. After centrifugal drying, these were followed by treatments in anionic polyacrylic acid, poly-acrylamide, and starch solutions, respectively. The shell-enhanced fibers were formed into handsheets and their physical properties evaluated. The results show that building multiple shells on worn-out fiber surfaces can strengthen the fibers and paper. The simpler and more practical impregnation-centrifuging treatment provided the desired effects, whereas salting out the polymers produced somewhat superior fibers. The latter process, were impractical, however. The first pair of polymeric shells imparted marked strength improvement, whereas later layers had diminishing efficacies. Overall, the methods can improve fiber quality, attaining paper strength requirements without resorting to expensive measures. Alternate cationic polymer and filler powders were also deposited on fiber surface based on the micriparticle system in an anticipation of stiffness gains. Platy minerals, such as montmorillonite, bentonite, sericite, clay and talc were added following cationic PAM. After dewatering of polymer-pigment shelled fiber of one to 3 pairs of layers, handsheets either calendered or uncalendered were evaluated. The results indicate that regardless of calendaring, stiffness of the handsheets did not improve appreciably while certain other strength properties showed gains. We also attempted the novel starch gel filler addition method wherein tapioca starch and filers (PCC, sericite or clay) were mixed at high solids content of 50% and cooked until gelatinized. The filled handsheets were dried under various conditions and then tested for their properties. Improvements in strengths of modified filled paper were observed.

• Biomaterials Research
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• v.22 no.4
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• pp.235-248
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• 2018

Background: Injectable hydrogels have been extensively researched for the use as scaffolds or as carriers of therapeutic agents such as drugs, cells, proteins, and bioactive molecules in the treatment of diseases and cancers and the repair and regeneration of tissues. It is because they have the injectability with minimal invasiveness and usability for irregularly shaped sites, in addition to typical advantages of conventional hydrogels such as biocompatibility, permeability to oxygen and nutrient, properties similar to the characteristics of the native extracellular matrix, and porous structure allowing therapeutic agents to be loaded. Main body: In this article, recent studies of injectable hydrogel systems applicable for therapeutic agent delivery, disease/cancer therapy, and tissue engineering have reviewed in terms of the various factors physically and chemically contributing to sol-gel transition via which gels have been formed. The various factors are as follows: several different non-covalent interactions resulting in physical crosslinking (the electrostatic interactions (e.g., the ionic and hydrogen bonds), hydrophobic interactions, ${\pi}$-interactions, and van der Waals forces), in-situ chemical reactions inducing chemical crosslinking (the Diels Alder click reactions, Michael reactions, Schiff base reactions, or enzyme-or photo-mediated reactions), and external stimuli (temperatures, pHs, lights, electric/magnetic fields, ultrasounds, or biomolecular species (e.g., enzyme)). Finally, their applications with accompanying therapeutic agents and notable properties used were reviewed as well. Conclusion: Injectable hydrogels, of which network morphology and properties could be tuned, have shown to control the load and release of therapeutic agents, consequently producing significant therapeutic efficacy. Accordingly, they are believed to be successful and promising biomaterials as scaffolds and carriers of therapeutic agents for disease and cancer therapy and tissue engineering.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.93-106
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• 2000

One phase liquid crystal formula was developed by using of nonionic surfactants, polyols, water and oils and its physical property was investigated. At the system oft to 1 ratio of POE octyldodecyl ether series, which have Y type (branch type) hydrophobic group, and POE glyceryl monostearate series, Y type hydrophilic group, it was examined that the formula at 7:3, 6:4, and 5:5 ratio of nonionic surfactant : polyols, shows L$\alpha$ , a pattern which is a typical characteristic of liquid crystal structure under the cross microscope polarized film. As results of L$\alpha$ phase diagram study, the formula which had high hydrophilic nonionic surfactant and the 7:3 ratio of nonionic surfactant : polyol appeared to increase the amount of oil containment and to be capable of the lamella formation. Besides it was examined that lamellar liquid crystal formula could contain about 25-40% water between lamella layers and it was transformed into w/o emulsion following as water content increased. When the lamella gel was applied into a human skin, it was investigated that it had effectiveness in increasing transepidermal water content of the skin.