• Korean Journal of Food Science and Technology
• /
• v.29 no.3
• /
• pp.601-608
• /
• 1997

In order to search for the way to utilize rice hull as a renewable resource, the inhibition on ${\alpha}-glucosidase$ and the fractionation of rice hull extract was investigated. An ethanol extract of rice hull from Japonica-type rice seeds exhibited 30% inhibitory activity on rat intestinal brush border ${\alpha}-glucosidase$ (1.4 mU/mL) in vitro at the concentration of 0.8 mg/mL using 6 mM p-nitrophenyl ${\alpha}-D-glucopyranoside$ as a substrate $(IC_{50}\;162\;mg/mL)$. Among the fractions obtained by partitioning the ethanol extract successively with solvents, the ethyl acetate fraction at the concentration of 0.8 mg/mL was found to exhibit the most potent inhibitory activity i.e. 65% inhibition of ${\alpha}-glucosidase\;(IC_{50}\;0.14\;mg/mL)$. Silica gel column chromatography of the ethyl acetate fraction exhibited slightly higher (90%) inhibitory activity, and its subsequent fractionation by Sephadex LH-20 column chromatography did not improve inhibitory activity. Considering the inhibitory activity and yield, the ethyl acetate fraction obtained by the solvent-partitioning process would be a candidate for the hypoglycemic food if it has in vivo effectiveness.

• Korean Chemical Engineering Research
• /
• v.49 no.6
• /
• pp.840-845
• /
• 2011

Degradation products of agarose are biologically active and thus used as an ingredient in pharmaceuticals or functional cosmetics. Furthermore, it has been strongly considered as a substrate for bio-ethanol fermentation. Recently, we isolated new agarase-producing microorganism, Pseudoalteromonas sp. from south sea of Korea. In this study, we aimed to separate and purify the agarase from culture broth of this strain. Separation of agarase was performed by ion- exchange chromatography on DEAE-Sepharose resin. Equilibrium pH and volume ratio of resin to the amount of protein were optimized for the efficient adsorption of protein. 410 ${\mu}g$ of protein was completely adsorbed to 3 mL of resin at pH 7.5. The total amount of eluted protein increased as NaCl concentration increased to 400 mM at isocratic elution. Agarase was separated by linear gradient elution of NaCl (0~1,000 mM). Three major protein peaks were observed and the presence or absence of agarase in these eluted proteins was measured by Lugol's staining technique. Only six eluted protein fractions showed strong agarase activity.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.6
• /
• pp.529-538
• /
• 2016

The simplified plate theory is presented for static and free vibration analysis of power-law(P) and sigmoid(S) Functionally Graded Materials(FGM) plates. This theory considers the parabolic distribution of the transverse shear stress, and satisfies the condition that requires the transverse shear stress to be zero on the upper and lower surfaces of the plate, without the shear correction factor. The simplified plate theory uses only four unknown variables and shares strong similarities with classical plate theory(CPT) in many aspects such as stress-resultant expressions, equation of motion and boundary conditions. The material properties of the plate are assumed to vary according to the power-law and sigmoid distributions of the volume fractions of the constituents. The Hamilton's principle is used to derive the equations of motion and Winkler-Pasternak elastic foundation model is employed. The results of static and dynamic responses for a simply supported FGM plate are calculated and a comparative analysis is carried out. The results of the comparative analysis with the solutions of references show relevant and accurate results for static and free vibration problems of FGM plates. Analytical solutions for the static and free vibration problems are presented so as to reveal the effects of the power law index, elastic foundation parameter, and side-to-thickness ratio.

• Journal of Ginseng Research
• /
• v.39 no.4
• /
• pp.398-405
• /
• 2015

Background: Ginseng has been used as a tonic for invigoration of the human body. In a previous report, we identified a novel candidate responsible for the tonic role of ginseng, designated gintonin. Gintonin induces $[Ca^{2+}]_i$ transient in animal cells via lysophosphatidic acid receptor activation. Gintonin-mediated $[Ca^{2+}]_i$ transient is linked to anti-Alzheimer's activity in transgenic Alzheimer's disease animal model. The previous method for gintonin preparation included multiple steps. The aim of this study is to develop a simple method of gintonin fraction with a high yield. Methods: We developed a brief method to obtain gintonin using ethanol and water. We extracted ginseng with fermentation ethanol and fractionated the extract with water to obtain water-soluble and water-insoluble fractions. The water-insoluble precipitate, rather than the water-soluble supernatant, induced a large $[Ca^{2+}]_i$ transient in primary astrocytes. We designated this fraction as gintonin-enriched fraction (GEF). Results: The yield of GEF was approximately 6-fold higher than that obtained in the previous gintonin preparation method. The apparent molecular weight of GEF, determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was equivalent to that obtained in the previous gintonin preparation method. GEF induced $[Ca^{2+}]_i$ transient in cortical astrocytes. The effective dose (ED50) was $0.3{\pm}0.09{\mu}g/mL$. GEF used the same signal transduction pathway as gintonin during $[Ca^{2+}]_i$ transient induction in mouse cortical astrocytes. Conclusion: Because GEF can be prepared through water precipitation of ginseng ethanol extract and is easily reproducible with high yield, it could be commercially utilized for the development of gintoninderived functional health food and natural medicine.

• Food Science and Preservation
• /
• v.16 no.1
• /
• pp.109-114
• /
• 2009

To develop Salicornia herbacea as a functional food material, crude polysaccharides and saponins were isolated from 80% ethanolic extracts of Salicornia herbacea using Diaion HP-20 column chromatography, and biological activities including anti-oxidation, anti-proliferation of cancer cells, and immune activities were investigated. The hydrogen-donating properties of crude polysaccharides and saponins were above 20% at $500{\mu}g/mL$ concentration. The reducing power of fractions increased in a dose-dependent manner. Crude polysaccharides and saponins at $500{\mu}g/mL$ inhibited more than 20% and 50% of proliferation by PC-3 and HT-29 human cancer cells, respectively. The anti-oxidative and anti-cancer properties of crude saponins were higher than those of crude polysaccharides. Also, proliferation in spleen cells and (nitric oxide) NO production in RAW264.7 macrophages treated with crude polysaccharides increased in a dose-dependent manner compared with the untreated control cells. However, crude saponins at concentration greater than $500{\mu}g/mL$ resulted in decreases in immune activities. Immune activities of crude polysaccharide were greater than those of crude saponins. These results indicate that Salicornia herbacea may be used as functional food materials.

• Journal of the East Asian Society of Dietary Life
• /
• v.18 no.3
• /
• pp.361-367
• /
• 2008

This study examined the physicochemical properties of rice embryo in order to investigate the antioxidative effect of black rice bran pigment fraction on rice embryo lipid oxidation. Color stability of rice bran pigment fraction and acid value of added rice embryo were determined at various conditions of pH, temperature, and storage time. Rice embryo contained more crude protein (22.1%) compared to the rice bran (9.4%). However, rice embryo had a higher lipid content than rice bran, causing lipid oxidation during storage. Pigment fraction were relatively stable in acidic pH of 3.0 stored at $4^{\circ}C$ for 9 days. Rice embryo showed increased acid value with increased storage time and temperature. Furthermore, rice embryo with pigment fraction resulted in lower acid value compared to the control group. Therefore, addition of black rice bran pigment fractions to rice embryo improved storage capacity.

• Radiation Oncology Journal
• /
• v.7 no.2
• /
• pp.171-183
• /
• 1989

A general effect for cell proliferation has been incorporated into Roesch's survival equation (Accumulation Model). From this an isoeffect formula for the low dose-rate regimen is obtained. The prediction for total doses equivalent to 60Gy delivered at the constant dose-rate over 7 days agrees well with the dose-time data of Paterson and of Green, when the parameter ratio A/B (${\approx}{\alpha{\mu}}/2{\beta}\;where\;{\mu}$ is the repair rate) is chosen to be 0.7Gy/h. When a constant proliferation rate and known facts of division delay are assumed, an isoeffect relation between low dose-rate treatment and acute dose-rate treatment can be derived. This formula in the regimens where proliferation is negligible predicts exactly the data of Ellis that 8 fractions of 5 Gy/day for 7 days are equivalent to continuously applied 60Gy over 7days, provided the A/B ratio is 0.7 Gy/h and the $\alpha/\beta$ ratio is 4Gy. Overall agreement between the clinical data and the predictions made by the formula at the above parameter values suggests that the biologcal end points used as the tolerance level in the studies by Paterson, Green, and Ellis all agree and they are not entirely the early effects as generally assumed. The absence of dose-rate effects observed in the mouse KHT sarcoma can better be explained in terms of a large value for the A/B ratio. Similarly, the same total dose used independently of the dose-rate to treat head and neck tumors by Pierquin can be justified.

• Korean Journal of Food Science and Technology
• /
• v.34 no.3
• /
• pp.529-532
• /
• 2002

The angiotensin converting enzyme (ACE) inhibitory activity in peptic hydrolysate of raw anchovy cooking discards was 51.3% at 1 mg of protein per $100\;{\mu}L$ sample solution. While, after the treatment of pepsin for 4 h, was 65.8%. The crude peptides fractionated through Bio-gel P-2 column chromatography consisted of five fractions $({P-1}{\sim}{P-5})$ and had maximum inhibitory activity in the fraction P-2 ($IC_{50}$=0.319 mg protein/mL). The fraction P-2 was rich in aspartic acid, glutamic acid, and glycine.

• Journal of Korea Foundry Society
• /
• v.43 no.6
• /
• pp.279-285
• /
• 2023

In order to predict the mechanical properties of ductile cast iron heat treated in an intercritical temperature range, samples machined from cast iron with a tensile strength of 450 MPa were heat-treated at various intercritical temperatures and air-cooled, after which a microstructural analysis and Brinell hardness test were conducted. As the heat treatment temperature was increased in the intercritical temperature range, the ferrite fraction in the ductile cast iron decreased and the pearlite fraction increased, whereas the nodularity and nodule count did not change considerably from the corresponding values in the as-cast condition. The Brinell hardness values of the heat-treated ductile cast iron increased gradually as the heat treatment temperature was increased. Based on the measured alloy composition, the fraction of each stable phase and the hardness model from the literature, the hardness of the ductile cast iron heat treated in the intercritical temperature range was calculated, showing values very similar to the measured hardness data. In order to check whether it is possible to predict the hardness of heat-treated ductile cast iron by using the phase fraction obtained from thermodynamic calculations, the volumes of graphite, ferrite, and austenite in the alloy were calculated for each temperature condition. Those volume fractions were then converted into areas of each phase for hardness prediction of the heat-treated ductile cast iron. The hardness values of the cast iron samples based on thermodynamic calculations and on the hardness prediction model were similar within an error range up to 27 compared to the measured hardness data.

• Communications of Mathematical Education
• /
• v.38 no.2
• /
• pp.187-213
• /
• 2024

This study aims to investigate the impact of mathematical journal writing activities on sixth-grade students' mathematics anxiety and the 'writing' aspect of mathematical communication. For this purpose, 27 sixth-grade students participated in 14 sessions of mathematical journal writing activities while learning division with fractions and decimals. Mathematics anxiety was measured using a questionnaire, with pre- and post-test results statistically analyzed. Mathematical communication in the 'writing' domain was quantitatively measured using an analytical framework to track changes in levels. Additionally, 13 students were interviewed to examine the impact of journal writing on mathematics anxiety and mathematical communication in more detail. The study found that among the four main factors of mathematics anxiety, there was a significant reduction in the subject-specific and environmental factors. The average levels of 'expression' and 'explanation' in the 'writing' domain of mathematical communication gradually increased, with specific teacher feedback supporting improvements in students' communication levels. Based on these findings, the study suggests implications for the use and guidance of mathematical journal writing activities in school settings.