• Journal of Life Science
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• v.21 no.1
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• pp.81-88
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• 2011

Biological activities (${\alpha},{\alpha}'$-diphenyl-${\beta}$-picrylhydrazyl (DPPH) free radical scavenging activity, fibrinolytic activity and reducing power) and biochemical properties (protein content and electrophoretical protein patterns) were examined in solid state fermentation with Bacillus subtilis and Aspergillus kawachii using silkworm powder (SP) as substrate. The highest protein contents and free radical scavenging activities were seen in the SP fermented for 12 days with B. subtilis and A. kawachii, and these were in a time-dependent manner. The highest reducing power was seen in the SP fermented for 6 days with B. subtilis and for 12 days with A. kawachii, respectively. The highest fibrinolytic activities were seen in silkworm fermented for 6 days with B. subtilis and A. kawachii, but this activity was higher in the A. kawachii fermented SP than that of B. subtilis. When total protein patterns were analyzed by SDS-polyacrylamide gel electrophoresis (PAGE), the proteins of the SP fermented with B. subtilis for 3 days were completely degraded, while the protein degradation in the SP fermented with A. kawachii occurred after 12 days and this degradation increased proportionally to culture time. As a result, the SP fermented with both B. subtilis and A. kawachii showed higher fibrinolytic activities after 6 days of fermentation and antioxidative activity after 12 days, indicating that physiological activities of the fermented SP using these strains were highly improved compared to the unfermented SP, and that this compound could be a candidate material as a dietary supplement of healthy functional foods.

• Journal of the Korean Electrochemical Society
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• v.8 no.2
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• pp.82-87
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• 2005

The cathode material, $LiNi_{0.5}Mn_{1.5}O_4$, for high voltage applications of Li-ion batteries exhibits impurity phases due to oxygen deficiency during the high temperature heat treatment. The impurity phase reduces the electrochemical properties of the electrode since the deficiency spinel structure disturbs the lithium ion intercalation and deintercalation. In this study, Cr-substituted $LiNi_{0.5-x}Mn_{1.5}Cr_xO_4(0{\leq}x{\leq}0.05)$ powders are synthesized by a sol-gel method in order to reduce the amount of the impurity phases in the $LiNi_{0.5-x}Mn_{1.5}Cr_xO_4$. Thermal analysis of the cathode material shows that the $LiNi_{0.5}Mn_{1.5}O_4$ without Cr substitution looses $2\%$ of its weight due to oxygen deficiency but the amount of weight loss is diminished when Cr is substituted. XRD analysis also supports the reduction of the impurity phases in the cathode after chromium substitution, suggesting that the improvement of the electrochemical properties such as the capacity retention and electrochemical stability are attributed to the low content of impurity phases in the Cr-substituted $LiNi_{0.5-x}Mn_{1.5}Cr_xO_4.$

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.99-106
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• 1999

Ultra-high molecular weight polyethylene (UHMWPE) was crosslinked in the melt state to enhance wear resistance, Dicumyl peroxide (DCP) and triallyl cyanurate (TAC) was used as a crosslinking agent and a promoter, respectively. With increasing amount of DCP and TAC used, gel content of crosslinked UHMWPE (XUMPE) increased, while the melting temperature, crystallizaiton temperature, crystallinity, and tensile properties decreased. The results of pin-on-disk wear test and ball-on-disk test with small applied load showed reduced wear volumes of XUMPE from that of the unmodified UHMWPE. As the wear mechanism effected in the experimental condition of this study was thought to be deformation rather than adhesion or fatigue, a new parameter, the ratio of maximum contact stress to yield stress, was proposed to correlate well with observed wear resistance. In ball-on-disk wear test with larger applied load, XUMPE showed higher wear volumes than that of the unmodified UHMWPE which were accompanied with increased friction coefficients and surface roughness of the wear tracks. When contact stress was well above yield stress, the failure of XUMPE, as well as deformation, was thought to be much accelerated.

• Applied Biological Chemistry
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• v.49 no.3
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• pp.215-220
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• 2006

Response surface methodology was implemented to determine an optimal extraction condition in Phellinus linteus water extract. Extraction was performed on 10 experimental conditions including independent variables such as extraction time $(1{\sim}5\;hrs)$ and water volume over sample (sample : $H_2O$ = 1 : $40{\sim}200$, W/V), color browning, reducing and total sugar, that were based on the significant levels of 10% of central composition design. Color browning, reducing and total sugar contents were found to be more affected when the water volume was increased rather than extraction time. Maximum extraction condition was acquired at extraction time of $3.0{\sim}4.5\;hrs$ and water volume of $40{\sim}58.2\;ml$. Being extracted at the optimal extraction condition two of the free sugars, sucrose (0.126%) and glucose (0.012%), were detected. Total content of the free amino acids was found to be $503.26\;{\mu}g%$. Among them, essential amino acid contents were revealed as 5.4%. One major peak from gel permeation chromatography contained polysaccharide(s) with the molecular weights of 10 KDa.

• Journal of Applied Biological Chemistry
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• v.55 no.2
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• pp.79-83
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• 2012

It has been known that the proteome profiles in the period of growth and development of rice are changed by the growth conditions including temperature, soil, and fertilization. In this study, the proteome profiles of Odae polished white rice grown in Chulwon and Chilgog were compared on 2-dimensional(D) gels. The differentially expressed proteins were selected from the 112 identified total proteins and classified into functional groups. The most significantly differentially expressed proteins were stress responsive proteins; Ent-kaur-16-ene synthase, which is responsible for synthesizing a plant hormone gibberellin, was expressed in Chulwon rice and heat shock proteins were in Chilgog rice, respectively. Xylanase inhibitor protein, which inhibits the enzyme xylanase produced by pathogenic fungi and Bacilli, was expressed significantly high in Chilgog rice grown at high temperature. Differential expressions of transporter proteins were observed both in Chulwon and Chilgog rice. Regarding the facts that Chilgog rice contained relatively higher amount of proteins than Chulwon rice and Chulwon rice showed large number of proteins were differentially expressed, it can be concluded that different cultivation conditions could change the protein expression profiles in rice in various ways, including elevation of protein amount or differential expressions of specific proteins, etc. The results suggest that the characteristics of the profiles of the proteome in the polished white rice are definitely changed by the environmental factors including high temperature. The results can be utilized for the development of the proper cultivation conditions for the production of high quality rice with good palatability.

• Polymer(Korea)
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• v.24 no.3
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• pp.389-398
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• 2000

Transparent, abrasion resistant coatings with 4~13 ${\mu}{\textrm}{m}$ thickness were prepared by spin-coating on polycarbonates with organic/inorganic hybrid solutions, followed by UV curing and heat treatment at 12$0^{\circ}C$ for 12 hours. The coating solutions were composed of inorganic phase and organic phase in 0:100, 20:80, 30:70, 50:50, 80:20 wt% ratios, respectively, mixed with photoinitiator, senaitizer and surfactant. The inorganic phase was formed by sol-gel reaction of TEOS and silane coupling agent MPTMS in 1 : 2 or 2 : 1 molar ratios, the organic phase consisted of difunctional urethane acrylate oligomeric resin, multifunctional acrylate TMPTA and HDDA in 4 : 3 : 3 wt% ratio. The coating systems were investigated by FT-IR, $^{29}$ Si-NMR spectra. In addition, TGA/DSC for thermal analysis and SEM, AFM observation for coated surface were examined. Gererally, the homogeneity of phases, the surface smoothness of coating and abrasion resistance were improved with the higher content of inorganic component. Namely, coating system with below 10 $\AA$ surface roughness and T$_{g}$ of 15$0^{\circ}C$ showed only 10% decrease in light transmittance after abrasion test, whereas uncoated polycarbonate substrate exhibited 46% decrease..

• Korean Journal of Food Science and Technology
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• v.7 no.3
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• pp.109-114
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• 1975

Domestic seaweeds Gracilaria verrucosa collected from coastal areas of Namhae, Wando and Yeosoo, Korea were subjected to the examination of yield and quality of agar prepared according to various pretreatment conditions. In alkali treatment at high temperature, higher alkali concentration for one-hour period at $90^{\circ}C$ gave rise to higher yield of agar. In acid treatment, higher yield was obtained by higher acid concentration and longer treating period. Alkali treatment at room temperature gave rise to a slightly decreased yield at higher alkali concentration and longer treating time. Total nitrogen and crude ash of agar samples were greatly decreased by pretreatments. Jelly strength, gelation ability, gelation point and viscosity of agar samples tended to increase as the alkali-treating condition of seaweed became stronger. It was shown that sulfur content of agar had a high negative correlation with jelly strength of its gel. Various alkali treatments of seaweed at room temperature showed no marked difference in agar quality and did not exhibit any good effect comparable to alkali treatment at high temperature.

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.269-275
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• 2014

We developed a competitive indirect enzyme-linked immunosorbent assay (ciELISA) for determining the buckwheat content in processed foods by using rabbit polyclonal antibodies against buckwheat proteins (BWP). The detection limit of this assay was $0.05-100{\mu}g/mL$. The cross-reactivities of the anti-BWP antibodies toward BWP, buckwheat flour, whole buckwheat, and cereals (wheat flour, whole wheat, black bean, mung bean, red bean, brack rice, brown rice, glutinous rice, white rice, millet, African millet, nonglutinous millet, adlay, and rye) were 100, 17.9, 11.8, and 0%, respectively. Thus, the antibodies were found to be specific for buckwheat only. When buckwheat flour was heated for 30 min, the mean assay recoveries of BWP were 83.0% at $60-90^{\circ}C$ and 44.5% at $100^{\circ}C$. The spike test showed that the mean assay recoveries of buckwheat from raw noodle, boiled noodle, starch gel, and cereal flour were 99.1, 98.6, 81.1, and 104%, respectively. For the 22 commercial items tested, the qualitative coincidence ratio of assay result and the corresponding value indicated on the item's package label was 100%. However, the average quantitative coincidence ratios from 12 commercial items were 31.6%. Thus, the results suggest that ciELISA is an efficient tool to detect buckwheat in processed foods.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.973-982
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• 2017

Gastrodia elata Blume often has been used for the treatment of headaches, convulsions, hypertension, and neurodegenerative diseases. The main active constituents are gastrodin, 4-hydroxybenzyl alcohol, vanillyl alcohol, 4-hydroxybenzylaldehyde and parishin A, B, C and E. Because Gastrodia elata has also unacceptable off-odor (swine barnyard-like) for food, there is a need to reduce it as well as allow for greater utilization as a functional food materials. In this study, a major off-odor producing substance of Gastrodia elata was fractionated by steam distillation and silica gel column chromatography. The substance was identified as p-cresol(4-methyl phenol) by GC-MS analysis and comparison of the retention time with that of an authentic compound in GC. The content of p-cresol in fermented Gastrodia elata was decreased. A fermented sample of Latobacillus sakei for 2 days was reduced to 54.7%, when compared with a unfermented sample. The five parishin derivatives in Gastrodia elata were identified by HPLC-MS analyses, and a comparison of HPLC retention times with those of authentic compounds. When compared with parishin derivatives of an unfermented Gastrodia elata, those of Gastrodia elata fermented by L. sakei, increased to 18.3% for 2 days. Increases of about 14.0~38.4% of the total phenolic compounds and 57.4~77.3% total flavonoids were found in fermented extracts, by 3 lactic acid bacteria strains. They were compared with $97.1{\pm}2.9{\mu}g/g$ and $40.9{\pm}2.0{\mu}g/g$ in the unfermented control, respectively. The extracts of Gastrodia elata Blume that were fermented by lactic acid bacteria had higher DPPH free radical scavenging activity and FRAP reducing power than the unfermented control.

• Elastomers and Composites
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• v.38 no.3
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• pp.213-226
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• 2003

The cure and rheological behavior of diglycidyl ether of bisphenol F/nadic methyl anhydride resin system with the kinds of imidazole were studied using a differential scanning calorimeter (DSC) and a rotational rheometer. The isothermal traces were employed to analyze cure reaction. The DGEBF/ anhydride conversion profiles showed autocatalyzed reaction characterized by maximum conversion rate at $20{\sim}40 %$ of the reaction. The rate constants ($k_1,\;k_2$) showed temperature dependance, but reaction order did not. The reaction order (m+n) was calculated to be close to 3. There are two reaction mechanisms with the kinds oi catalyst. The gel time was determined by using G'-G" crossover method, and the activation energy was obtained from this results. From measurement of rheological properties it was found that the logarithmic 1:elation time of fused silica filled DBEBF epoxy compounds linearly increased with the content of filler and decreased with temperature. The highly filled epoxy compounds showed typical pseudoplastic behavior, and the viscosity of those decreased with increasing maximum packing ratio.