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        검색결과 47

        3.
        2021.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Because of depletion of fossil fuel from the earth curst and increase of environmental concerns, in search of an efficient alternative to the traditional carbon black (CB), a biochar known as rice husk carbon (RHC) has been examined here as a filler material to develop the EPDM composite. In this regard, the ball milled RHC was further treated with ultrasonic wave and used with or without its surface treatment by the silane coupling agent [i.e., 3-mercaptopropyl triethoxysilane (3-MPTMS)]. Among the RHC, ultrasonic treated RHC (UHC) and silane treated UHC (USHC), the EPDM composite of USHC showed nearly similar tensile strength to that of the CB (e.g., CB: 33.88 kgf/cm2, USHC: 31.38 kgf/cm2 at 20 wt% filler loading) with an enhanced elongation at break (e.g., CB: 206%, USHC: 342% at 20 wt% filler loading) and surprisingly much less compression set value (CB: 40.87%, USHC: 18.95% even after 40 wt% of filler loading). Compared to RHC, the UHC also showed its better performance next to the USHC. In addition to presence of both the carbon and silica in RHC and additional silica within the flexible aliphatic chain in USHC, the disintegration of RHC by ultrasonic treatment towards its narrow particle distribution, smaller particle size, and increased surface area is considered very much effective to develop the corresponding high performance EPDM composites. Thus, the use of waste material, i.e., rice husk through the ultrasonication of RHC followed by its surface treatment can be used as a potential filler material to prepare the environment friendly and cost effective high performing composites to be used in different efficient end products, and motivated further for industrial upscaling.
        4,000원
        4.
        2021.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Graphene fiber is considered as a potential material for wearable applications owing to its lightness, flexibility, and high electrical conductivity. After the graphene oxide (GO) solution in the liquid crystal state is assembled into GO fiber through wet spinning, the reduced graphene oxide (rGO) fiber is obtained through a reduction process. In order to further improve the electrical conductivity, herein, we report N, P, and S doped rGO fibers through a facile vacuum diffusion process. The precursors of heteroatoms such as melamine, red phosphorus, and sulfur powders were used through a vacuum diffusion process. The resulting N, P, and S doped rGO fibers with atomic% of 6.52, 4.43 and 2.06% achieved the higher electrical conductivities compared to that of rGO fiber while preserving the fibrious morphology. In particular, N doped rGO fiber achieved the highest conductivity of 1.11 × 104 S m−1, which is 2.44 times greater than that of pristine rGO fiber. The heteroatom doping of rGO fiber through a vacuum diffusion process is facile to improve the electrical conductivity while maintaining the original structure.
        4,000원
        10.
        2019.04 구독 인증기관·개인회원 무료
        Three ambrosia beetle species, Xyleborus glabratus, Monarthrum mali, and Euwallacea fornicatus belong to subfamily, Scolytinae, showing similar morphology and body size, but their flight capability and patterns showed species-specific. Body length of Xyleborus glabratus and Monarthrum mali was negatively correlated with flight capabilities; shorter beetles performed longer average flights, longer single flights, total flight distance, and total flight time. Elytral length also was negatively correlated with flight distance in X. glabratus and M. mali. Conversely, only average flight time of E. fornicatus was positively correlated with body length, pronotal width, and elytral length. Body length had no effect on the flight velocity of any of the three beetle species examined. Therefore, our results indicate that body size characteristics of ambrosia beetles differentially influence on their dispersal by species.
        11.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pigs are considered as optimal donor animal for the successful xenotransplantation. To increase the possibility of clinical application, genetic modification to increase compatibility with human is an important and essential process. Genetic modification technique has been developed and improved to produce genetically modified pigs rapidly. CRISPR/Cas9 system is widely used in various fields including the production of transgenic animals and also can be enable multiple gene modifications. In this study, we developed new gene targeting vector and enrichment system for the rapid and efficient selection of genetically modified cells. We conducted co-transfection with two targeting vectors for simultaneous inactivation of two genes and enrichment of the genetically modified cells using MACS. After this efficient enrichment, genotypic analysis of each colony showed that colonies which have genetic modifications on both genes were confirmed with high efficiency. Somatic cell nuclear transfer was conducted with established donor cells and genetically modified pigs were successfully produced. Genotypic and phenotypic analysis of generated pigs showed identical genotypes with donor cells and no surface expression of α-Gal and HD antigens. Furthermore, functional analysis using pooled human serum revealed dramatically reduction of human natural antibody (IgG and IgM) binding level and natural antibody-mediated cytotoxicity. In conclusion, the constructed vector and enrichment system using MACS used in this study is efficient and useful to generate genetically modified donor cells with multiple genetic alterations and lead to an efficient production of genetically modified pigs.
        4,000원
        13.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Shrimps infected with WSSV (White Spot Syndrome Virus) generally exhibit white spots in their inner space of carapaces as an acute clinical sign. In an effort to identify the correlation between this acute clinical sign and the condition, the index factors (RNA/DNA concentration and ratio, trypsin activity) were analyzed. A total 580 farmed Fenneropenaeus chinensis and 130 Lithopenaeus vannamei were collected from western and southern fifteen outdoor ponds in Korea. The status of the white spot pathology was divided into four stages (stage 0, stage I, stage II, and stage III), in accordance with the clinical signs as to the size and area of white spots. A significant decrease in RNA concentration and RNA/DNA ratio for multi-infected fleshy prawn (WSSV and vibrio sp.) occurred during the stage III (the whole carapace is covered with a white spot). In particular, RNA/DNA ratio was significantly lower as 1.47±0.04 than other groups. A similar trend was also found in the single infection (WSSV), but the decrease was less than the multi-infection. In the species comparison, both species were vulnerable to the multi-infection, but L. vannamei was more sensitive than F. chinensis (ANOVA, p<0.05): A significant decrease in RNA concentration and RNA/DNA ratio was first found in stage II for the former species, while it was found in stage III for the latter species. Trypsin activity was also showed a similar tendency with nucleic acid variation. Multi-infected shrimp showed drastically decrease of trypsin activity. According to the results, clinical signs of the white spot under carapace have an only physiological effect on shrimp if they covered entirely with white spots.
        4,000원
        14.
        2016.04 구독 인증기관·개인회원 무료
        The objective of this study was to evaluate size-different chitosan nanoparticles as a CO2 indicator. CO2 gas is dissolved to form H2CO3 which makes the solution acidic. Chitosan is acid soluble and its appearance (turbidity) changes depending on pH in aqueous solution. Two size-different chitosan nanoparticles were fabricated by ionic gelation between chitosan (0.30 and 0.50%, w/v) and 0.07% sodium tripolyphosphate (TPP) solution. The sizes of chitosan nanoparticles were 630.77 and 1194.87 nm, respectively. To investigate the effect of chitosan nanoparticles as CO2 indicator, the initial pH of chitosan nanoparticle suspension was adjusted to 8.0. Thereafter, 100% CO2 gas was injected into the chitosan nanoparticle suspension, and the changes of pH and absorbance (600 nm of absorption wavelength) of the suspension over time were measured for 28 min. Absorbance at the appearance transition and its corresponding time was calculated using logistic function (R2> 0.99).As a result, pH of chitosan nanoparticle suspension decreased rapidly under CO2 gas injection for 10 min and finally reached around 6.0. In addition, there was significant difference in appearance transition time which was6.62 and 12.45 min for small- and large-sized chitosan nanoparticle suspensions, respectively. This study suggests that chitosan nanoparticle suspension might be useful as a food quality indicator for CO2 emitting foods such as fermented foods.
        15.
        2009.08 구독 인증기관·개인회원 무료
        The objective of this experiment was to evaluate growth performance in dairy goats (Saanen) fed total mixed ration (TMR) of different nutrition levels. Twenty four growing female goats of 8 months of age were randomly assigned to one of four TMRs; low energy-low crude protein (CP) TMR (control), high energy-low CP TMR (T1), low energy-high CP TMR (T3) and high energy-high CP TMR (T4). The content of total digestible nutrients (TDN) and CP in the control diet were 64% and 12%. The TDN content of the high energy TMR was 72% and the CP content of the high CP TMR was 14%. Feed intakes were 1,194g, 1,060g and 1,124g for T1, T2 and T3, respectively, being higher than control (1,039g). Average daily gain was also numerically higher for T1 (170.2g), T2 (114.5g) and T3 (154.9g) than for control (109.0g). The difference of average daily gain between T1 and control was statistically significant (P<0.05). Although there were no significant differences in feed intake (% of body weight) between treatments, feed conversion ratios showed different responses; T1 (7.01) and T3 (7.26) being higher than T2 (9.26) and control (9.53). The increases of heart girth were 11.8㎝, 10.0㎝ and 11.4㎝ for T1, T2 and T3, respectively, being higher than control (8.1㎝).
        19.
        2019.02 KCI 등재 서비스 종료(열람 제한)
        Background: This study was conducted to investigate the effects of fertilization with the application of mixed organic matter after cultivating green manure crops on the growth and saponin content of Codonopsis lanceolata Trautv. Methods and Results: Five type of cultivation of green manure crops were done: hairy vetch as a single seedling crop (HV), hairy vetch and rye as a mixture of seedling (HV/R), additional fertilization with mixed organic matter after cultivation of a seedling mixture (HV/R/MO), chemical fertilizer (CF), and a non-treated control (NT). The total nitrogen content was the highest in the HV/R/ MO treatment, followed by the HV, CF, HV/R and NT treatments, respectively. Nitrogen fixation was higher in the single seedling treatment with hairy vetch (HV) than in the treatment with a mixture of hairy vetch and rye seedling (HV/R). Moreover, the growth of C. lanceolata was greatly increased by the application of additional fertilizer after treatment with the mixture of hairy vetch and rye seedlings. The HV/R/MO treatment produced the highest total lancemaside content among the treatments, followed by HV, HV/ R, CF, and NT, respectively. Conclusions: It was verified that C. lanceolata experienced superior growth with the application of mixed organic matter as additional fertilizer after the cultivation of green manure crops, and the content of its major saponins, lancemasides were also increased by this treatment.
        20.
        2018.05 서비스 종료(열람 제한)
        Background : Codonopsis lanceolata has been used in traditional medicines, as its roots contain several kinds of triterpenoid saponin with high medicinal values. This study was conducted to select an advanced extraction method in C. lanceolata root. Methods and Results : Four extraction methods including 70% MeOH reflux and solvent fraction (n-hexane, ethyl acetate, butanol, water), water saturated butanol reflux, boiling water, and ultrasonication (70% MeOH) were investigated for the determination of major lancemasides. The total contents of lancemasides were the highest of 2.80 ㎎/g in ultrasonication, followed by boiling water, MeOH reflux, and water saturated butanol reflux extraction, in that order. Lancemaseide A was the most abundant saponin in all treatments, followed by lancemaside G, aster saponin, lancemaside B, in that order. The content of lancemaside B was very low compared to lancemaside A. Although four types of saponins were confirmed in this study, the others saponin such as foetidissimoside A could not be quantified due to very low content. Ultrasonication was evaluated as optimal extraction method and further studies were conducted to determine the optimal condition. The result compared to dry methods of sample [freeze-drying and shade dry (< 60℃)] before ultrasonication was superior shade dry to freeze-drying. The extract time and temperature were the best in 2 hr, 64℃ treatment, respectively, although there was no significant statically. Conclusion : The ultrasonication method was evaluated as relatively simpler and more efficient method due to short extraction time, small solvent consumption relative to conventional reflux method.
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