• Food Science and Preservation
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• v.14 no.4
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• pp.385-393
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• 2007

Much research is conducted on the biological activities of medicinal herbs, traditional plants, and agricultural products, cultivated in Korea. This study focused on optimization of hot-water extraction methods for such products, by analyzing and monitoring extraction characteristics using a response surface methodology. We found that the total phenolics contents, electron-donating abilities, and nitrite-scavenging abilities of extracts were significantly affected both by the solvent used for extraction, and by the nature of the particular herb or plant under study. The extraction efficiencies of valuable ingredients such as alliin, allicin, and total thiosulfinate, were greatly affected by extraction temperature, but not by extraction time or the solvent used. We elicited a regression formula for each variable. We first entered the optimal values of all extraction conditions giving active ingredients into the model. Next, we entered the optimal values of all extraction conditions favoring the retention of valuable antioxidant characteristics. Finally, we entered processing factors into the model. Overall, the optimal extraction was at $80^{\circ}C$ for 3.5 hr with 8.5 ml of solvent/g of sample. The predicted values of each variable were similar to the actual values.

• Food Science and Preservation
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• v.17 no.6
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• pp.861-866
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• 2010

We obtained hot-water extracts (HWE) and 70% (v/v) ethanol extracts (EE) from cultured wild ginseng roots (CWGR) and determined the saponin and total polyphenol contents, and antioxidant activities. The yields of freeze-dried powder from the HWE and EE were 27.86% and 18.33% (both w/w), respectively. The total polyphenol content of the EE (22.63 mg/g) was higher than that of the HWE (17.90 mg/g). Ginsenoside-Rb1 and -Rg1 contents of hot-air-dried CWGR were 17.90 mg/g and 22.63 mg/g, respectively. The electron-donating ability of HWE and EE were 2.82-60.58% and 3.88?70.88%, respectively, and the reducing powers ($OD_{700}$) were 0.02-0.17 and 0.07-1.90, respectively, at concentrations of 1-20 mg/mL. Thus, the HWE reducing power was markedly lower than that of the EE, but the SOD-like activity of the EE was significantly higher than that of the HWE. The nitrite-scavenging activities of HWE and EE were 9.25-19.18% and 11.94-53.49%, respectively, at concentrations of 1-20 mg/mL. Additionally, the TBARS (Thiobarbituric acid reactive substances, % value) of the EE (1-20 mg/mL) was 9.18-66.59%, thus 1.9-2.8-fold greater than that of the HWE (4.74-24.88%). In conclusion, we provide experimental evidence that extracts of CWGR may be natural antioxidants.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.257-263
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• 2000

Thermoelectric properties of the 0.05wt% $SbI_3$-doped n-type $Bi_2(Te_{0.95}Se_{0.05})_3$ alloy, prepared by melting/grinding and hot pressing, were investigated with variation of the annealing time up to 36 hours. The electron concentration of the 0.05wt% SbI$_3$-doped n-type $Bi_2(Te_{0.95}Se_{0.05})_3$ alloy decreased with increasing the annealing time. The figure-of-merit of the 0.05wt% $SbI_3$-doped n-type $Bi_2(Te_{0.95}Se_{0.05})_3$ alloy was improved from $2.1{\times}10^{-3}/K$ to $2.35{\times}10^{-3}/K$ by annealing at $500^{\circ}C$ for 3 hours. When annealed longer than 12 hours, however, the figure-of-merit decreased substantially due to the increase of the electrical resistivity.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.358-363
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• 2013

Lithium-ammonia (Li-$NH_3$) solutions are possible to be successfully made under the vacuum condition but there still remains a problem of undergoing stable and reliable decomposition in vacuum for high-efficiency thermoelectric power generation. This paper describes a new method for improving the thermoelectric conversion efficiency of Li-$NH_3$ solutions in vacuum. The proposed method uses a 'U'-shaped Pyrex vacuum tube for the preparation and decomposition of pure fluid Li-$NH_3$ solutions. The tube is shaped so that a gas passageway ('U') connecting both legs of the 'U' helps to balance pressure inside both ends of the tube (due to $NH_3$ gasification) during decomposition on the hot side. Thermoelectric experimental results show that solution reaction in the 'U'-shaped tube proceeds more stably and efficiently than in the 'U'-shaped tube, and consequently, thermoelectric conversion efficiency is improved. It is also proved that the proposed method can provide a reversible reaction, which can rotate between synthesis and decomposition in the tube, for deriving the long-time, high-efficiency thermoelectric power.

• Food Science and Preservation
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• v.14 no.2
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• pp.170-176
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• 2007

In this study, extract of Ailanthus altissimawere prepared using hot water under high pressure. The extract were examined for election donating ability (EDA), superoxide dismuase (SOD)-like activity, nitrite scavenging ability (NSA), xanthine oxidase inhibition levels, and tyrosinase inhibition ability. The EDA, using the 1,1-diphenyl-2-picrylhydrazyl method of root extract was 91.25% at 1.0mg/mL. The SOD-like activity of leaf extract was highest at 49.07% and the NSA was 93.33% at pH 1.2, and 85.40% at pH 3.0. The xanthine oxidase inhibitory levels of extracts of A. altissima roots, stems, and leaves were 92.09 97.44% when the extract were tested at 2.0mg/mL. The highest tyrosinase inhibition levels obtained from loot extract were 67.38% at 2.0mg/mL and 63.97% at 0.1mg/mL.

• Food Science and Preservation
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• v.19 no.4
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• pp.525-531
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• 2012

This study was conducted to evaluate the quality and anti-oxidant characteristics of different granule tea variants (WSMGT: granule tea prepared from sea mustard hot water extract; ASMGT: granule tea prepared from sea mustard autoclave extract; WSTGT: granule tea prepared from sea tangle hot water extract; and ASTGT: granule tea prepared from sea tangle autoclave extract) from sea tangle and sea mustard powder. The Color of WSTGT showed the highest $L^*$, $b^*$ values, and the lowest $a^*$ value. The water absorption binding agents in ASMGT were higher than those in WSMGT, WSTGT. and ASTGT. Binding agents on water absorption in ASMGT were higher than those of WSMGT, WSTGT, and ASTGT. The alginic acid content of ASMGT was highest. The total polyphenol and total flavonoid contents of ASMGT and ASTGT were highest. The electron donating ability and ferrous ion chelating activity in WSTGT greatly increased compared to those in the other granules tea variants. These results suggest that pressure extraction can be used in functional foods.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4102-4110
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• 2022

Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m². Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion 57 (2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 ℃, much below the permissible value of tungsten material (~1200 ℃). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-active-multijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ~3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5° toroidally from the 4.6 GHz LH system and is not magnetically connected.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.4
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• pp.198-205
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• 2023

We investigated the effects of Al and Mg on the microstructure and hardness of the coating layer of galvanized steel sheets, by thermodynamic calculations, X-ray diffraction, scanning electron microscopy, and Vickers hardness tests of Zn-0.2Al, Zn-6Al-2Mg, and Zn-10Al-5Mg coating layers. Regardless of the alloy composition of the galvanizing bath, a Fe-Al layer was observed between the coating layer and steel sheet. The Zn-0.2Al coating layer consists of major h.c.p. Zn phase and minor f.c.c. Al phase. The fraction of f.c.c. Al phase (containing a significant amount of Zn) of the coating layer increases with increasing the chemical composition of Al of the galvanizing bath. The h.c.p. MgZn₂ phase was formed in the Al/Mg-containing Zn-6Al-2Mg and Zn-10Al-5Mg coating layers, forming Zn-Al-MgZn₂ eutectic microstructure. The primary MgZn₂ phase was additionally formed in the Zn-10Al-5Mg coating layers containing high concentrations of Al and Mg. The Vickers hardness values of Zn-0.2Al, Zn-6Al-2Mg, and Zn-10Al-5Mg coating layers were 59.1 ± 1.2 HV, 161.2 ± 5.7 HV, and 215.5 ± 40.3 HV, respectively. The addition of Al and Mg increased the hardness of the coating layer by increasing the fraction of the Al phase (containing Zn) and MgZn₂ intermetallic compound, which were harder than the Zn phase.

• Journal of Mushroom
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• v.22 no.3
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• pp.92-101
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• 2024

Hair dyeing, hair perming, and daily hair dryer use can substantially damage hair. Consequently, the demand for products containing natural ingredients for the care of damaged hair is growing. Although polyphenols with antioxidant effects are often used for hair conditioning, few studies have focused on hair conditioning, and the potential of Sparassis latifolia mushroom extract for hair improvement has not been evaluated to date. In this study, the antioxidant activity of and polyphenol content in hot water, 70% and 100% ethanol (EtOH), n-hexane, ethyl acetate (EtOAc), and water extracts of S. latifolia were analyzed. A hair treatment containing S. latifolia extract was prepared, and its effect on damaged hair was evaluated. The highest antioxidant activity was observed in the hot water and EtOAc extracts. Moreover, polyphenol analysis using high-performance liquid chromatography and liquid chromatography-mass spectroscopy confirmed that the EtOAc fraction has relatively high contents of specific polyphenols beneficial for hair. Based on these results, a hair treatment containing S. latifolia extract was applied to damaged hair, and hair improvement was evaluated using hair thickness, tensile strength, and scanning electron microscopy. The hair treatment containing 70% EtOH extract effectively improved hair condition. We postulate that this improvement was caused by the high hydrophobic polyphenol content in the 70% EtOH extract.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.1-8
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• 2009

This study was investigated to analyze the contents of flavonoid and polyphenol compounds, and inhibitory activities of tyrosinase and antioxidation to measure physiological effect of reflux water extraction (WE), reflux ethanol extraction (EE) and hot water extract under high pressure (HWE) of Torreya nucifera seed. HWE yields the highest contents of flavonoid compounds (176.34 mg/g) and polyphenol compounds (112.95 mg/g). The tyrosinase inhibitory rates were $5.62{\sim}28.71%$ at 2.0 mg/mL and HWE showed the highest inhibition rate. The nitrite scavenging abilities of all extracts were over 90% at pH 1.2 and 3.0 at the concentration of 2.0 mg/mL. The superoxide dismutase (SOD)-like activities of HWE was the highest value of 33.58%. The electron donating abilities (EDA) were $66.46{\sim}89.72%$ and HWE was the highest when the extracts were tested at 0.1 mg/mL. The EDA of all extracts were decreased with an increment of the extracts concentrations. The xanthine oxidase inhibitory rate of HWE was the highest value of 89.29% at the concentration of 2.0 mg/mL and the WE and HWE were over 75% rate of xanthine oxidase inhibition at 0.5 mg/mL.