• Title, Summary, Keyword: phenolic

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Analysis of Thermal Conductivities of Carbon/Phenolic and Silica/Phenolic Ablative Composites by Laser Pulse Method (레이저 섬광법을 이용한 Carbon/Phenolic 및 Silica/Phenolic 내열복합재료의 열전도도 분석)

  • Kim, H.Y.;Kim, P.W.;Hong, S.H.;Kim, Y.C.;Yeh, B.H.;Jung, B
    • Composites Research
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    • v.12 no.3
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    • pp.75-83
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    • 1999
  • The thermal properties of carbon/phenolic and silica/phenolic ablative composites were investigated by measuring the heat capacity, thermal diffusivity and thermal conductivity. The heat capacities of carbon/ phenolic and silica/phenolic composites were calculated from differential scanning calorimeter curve. The thermal diffusivities of carbon/phenolic and silica/phenolic composites were measured by the laser flash method with varying laminated direction, i.e., with laminar direction and across laminar direction. The thermal diffusivities decreased with increasing temperature. The thermal conductivities of carbon/phenolic and silica/phenolic composites were calculated using the heat capacity, density and thermal diffusivity. The thermal conductivities increased with increasing temperature. The thermal conductivity of with laminar direction is two times higher than that of across-laminar direction in carbon/phenolic composite due to the directionality of thermal conductivity of carbon fiber. The thermal conductivities of two dimensional fiber reinforced composites were analyzed using the conductivities of constituents and volume fraction of each constituent. The thermal conductivities of carbon fiber and silica fiber were calculated from thermal conductivities of carbon/phenolic and silica/phenolic composites. The thermal conductivities of carbon/phenolic and silica/phenolic composites at RT were predicted from thermal conductivities of fiber and resin with varying the volume fraction of fiber.

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Phenolic Compounds in Persimmon Fruits and Stabilization of Discoloring Compounds (감의 페놀성 화합물과 변색관련 물질의 안정화)

  • 박용곤;김홍만;강윤한
    • The Korean Journal of Food And Nutrition
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    • v.13 no.2
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    • pp.103-110
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    • 2000
  • This study was conducted to determine changes in phenolic compounds of astrigent persimmons before and after softening process and evaluate discoloring properties of major phenolic compounds. Phenolic compounds in soft persimmons were mainly composed of catechins and chlorogenic acid. Although contents of phenolic compounds were reduced during the softening process, little change in the ratio of catechins to total phenolic compounds was observed. Most of phenolic compounds in damaged astringents persimmons were existed in the high molecular weight fraction and more phenolic compounds were extracted at the temperature higher than room temperature. To evaluate discoloring abilities of phenolic compounds, phenolic compounds were dissolved separately into water or 80% methanol. With presence of various amounts of anti-discoloring agents such as vitamin C, citric acid, and L-cystein, (+)catechin was significantly reduced.

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Analytical Methods for Phenolic Compounds in Water and Wastewaters(I) (Phenol류의 분석방법에 관한 연구(I))

  • 김낙주;신현진
    • Journal of Environmental Science International
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    • v.7 no.6
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    • pp.811-815
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    • 1998
  • Currently in Korea, standard operating procedure for the analyses of phenolic compounds in water is the spectrometric comparison of colors developed by 4-amino antipyrin with phenolic compounds. It is however that this method cannot identify individual compound and that some phenolic compounds do not react with 4-amino antipyrin. Spectrometric determinations of phenolic compounds were compared with chromatographic analyses of gas chromatography (GC) and high pressure liquid chromatography (HPLC) of various phenolic compounds. Individual phenolic compounds could be determined by both chromatographic methods but HPLC methods were more precise with lower detection levels in general.

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Synthesis of Triazole-functionalized Phenolic Resin and its Inherent Flame Retardant Property

  • Poduval, Mithrabinda K.K.;Kim, Tae-Hyun
    • Bulletin of the Korean Chemical Society
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    • v.35 no.11
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    • pp.3249-3253
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    • 2014
  • A novel triazole-functionalized phenolic resin was developed, and its thermal and flame-retardant properties were investigated. The triazole group was incorporated as a pendant unit on the phenolic resin via copper-mediated click chemistry between propargylated phenolic resin and benzyl azide. The newly-developed triazole-functionalized phenolic resin showed higher thermal stability and char yield, together with a reduced total heat release (THR), than the non-functionalized bare phenolic resin, indicating enhanced flame retardancy for the triazole-functionalized phenolic resin.

Composition and Antioxidative Characteristics of Phenolic Fraction Isolated from Soybean Fermented Food (콩 발효식품으로부터 분리한 페놀물질획분의 성분분석과 항산화 작용 특성)

  • 이정수;최홍식
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.26 no.3
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    • pp.383-389
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    • 1997
  • Doenjang(fermented soybean paste) was prepared by the series of processes including soaking, cooking, first fermentation(3 days at 30$\pm$2$^{\circ}C$) for the preparation of meju(soybean koji) after inoclulation of Aspergillus oryzae, and further fermentation (60 days at 30$\pm$2$^{\circ}C$) for the ripening after addition of salt 13% to meju. the crude phenolics extracted from defatted soybean and doenjang were fractionated onto the neutral phenolics(isofavonoids) and acidic phenolics(phenolic acids), respectively. Composition and antioxidative characteristics of phenolic fractions were determined. The neutral phenolic fractions contained genistin, genistein and daidzein; on the other hand, acidic phenolic fractions had syringic acid and seven other components. The content of genistin in doenjang dramatically decreased at the early stage of fermentation, whereas the content of genistein rather increased. In addition, the content of syringic acid of acidic phenolic fractions were increased during fermentation. These changes in individual phenolic components affected the antioxidative activity of neutral phenolics or acidic phenolics. antioxidative activity of phenolic compounds were evaluated during soybean fermentation. The antioxidative and free radical scavenging activity of neutral phenolic fractions and acidic phenolic fractions on linoleic acid autoxidation were also investigated.

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Use of Pellet Type Phenolic Foam as a Medium for Production of Plug Seedlings of 'Madison' Tomato (토마토 플러그 묘 생산을 위한 배지로서 펠릿형 Phenolic Foam의 이용)

  • No, Kyoung Ok;Kang, Jeong Hwa;Kim, Hye Min;An, Chul Geon;Jeong, Byong Ryong;Hwang, Seung Jae
    • Protected Horticulture and Plant Factory
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    • v.21 no.3
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    • pp.199-206
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    • 2012
  • This study was conducted in a glasshouse to examine the possibility of producing tomato plug seedlings in a newly-developed inert phenolic foam medium. Plug seedlings of 'Madison' tomato were grown in four pellet type media, Grodan rockwool, UR rockwool, phenolic foam LC, and phenolic foam LC-lite. Seed germination was checked for 7 days. Seedling growth was measured at 19 days after sowing. The greatest germination was obtained in the phenolic foam LC and phenolic foam LC-lite. Plant height, hypocotyl length, leaf area, dry weight, and fresh weight were significantly greater in the rockwool medium than those in the other media. However, the T/R ratio and stem diameter were the greatest in the phenolic foam LC than those in the other media. The total porosity and container capacity of the phenolic foam LC was higher than in the other media. The air space (%) was lowest in the phenolic foam LC. Overall, the phenolic foam LC and phenolic foam LC-lite produced seedlings with similar growth as the rockwool. These results suggested that both phenolic foam LC and phenolic foam LC-lite have potential to be used in production of plug seedlings of 'Madison' tomato.

Antioxidative Effect of Phenolic Acids in Defatted Perilla Flour on Soybean Oil (탈지들깨박 중 페놀산의 대두유에 대한 항산화 효과(I))

  • 조희숙;안명수
    • Korean journal of food and cookery science
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    • v.15 no.1
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    • pp.55-60
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    • 1999
  • Free phenolic acid, soluble phenolic acid ester and insoluble bound phenolic acid were extracted from defatted perilla flour. Their antioxidative effects were compared with those of BHA, AE and TBHQ for soybean oils by measuring acid and peroxide values at 60$^{\circ}C$ for 25 days. The patterns of these extracts were compared by using gas chromatography. Free phenolic acid and soluble phenolic acid ester extracts showed a higher antioxidative effects than BHA and AP. Among phenolic extracts, free phenolic acid showed the most effective antioxidant activity in soybean oil. Six types of free phenolic acid, 3 types of soluble phenolic acid ester, and 2 types of insoluble phenolic acid were found in the extract.

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Phenolic Acids and Antioxidant Activities of Wild Ginseng (Panax ginseng C. A. Meyer) Leaves

  • Seog, Ho-Moon;Jung, Chang-Hwa;Kim, Yoon-Sook;Park, Hyeon-Suk
    • Food Science and Biotechnology
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    • v.14 no.3
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    • pp.371-374
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    • 2005
  • The compositions and antioxidant activities of tree and hydrolyzed phenolic acids, which are aglycones of esterified phenolic acids, in wild ginseng leaves were investigated. The contents of tree and hydrolyzed phenolic acids in the wild ginseng leaves were $422.4\;{\pm}\;3.5$ and $319.6\;{\pm}\;5.7\;mg/100\;g$, respectively, as gallic acid equivalents. Free phenolic acids were composed of 55.3% benzoic acid derivatives and 44.6% phenylpropanoids. The major constituents of free phenolic acids in the ginseng leaves were syringic (139.4 mg/l00 g) and sinapic (131.2 mg/100 g) acids. On the other hand, hydrolyzed phenolic acids in the ginseng leaves were mainly composed of caffeic (59.4 mg/100 g), ferulic (49.5 mg/100 g), and p-coumaric (33.8 mg/100g) acids. Phenylpropanoid content was higher (82.7%) than benzoic acid derivatives (17.3%). $IC_{50}$ values of DPPH radical scavenging activity were $10.2\;{\mu}g/mL$ for tree phenolic acids and 8.0 mg/mL for hydrolyzed phenolic acids, as gallic acid equivalents. Hydrolyzed phenolic acids also exhibited higher hydroxyl and superoxide radical scavenging activities than free phenolic acids did. These results indicated that the antioxidant activities of the wild ginseng leaves were correlated more closely with phenylpropanoid contents than with total amount of phenolics.

Antioxidative Characteristics of Plant Phenolic Compounds (식물 phenolic compounds의 항산화성)

  • 최홍식;이창용
    • Journal of Life Science
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    • v.3 no.1
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    • pp.9-17
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    • 1993
  • 식물 특히, 우리가 섭취하고 있는 식품에 널리 존재하고 있는 phenolic compounds는 simple phenols과 phenolic acids, hydroxycinnamic acid derivatives 그리고 flavonoids 등의 세가지 종류들로 나누고 있다. 이들 물질은 일정수준의 항산화성, 항돌연변이원성, 항암성을 지니고 있다. 본 총설에서는 식물성 phenolic compounds의 특성, 산화작용과 항산화작용, phenolic compounds의 항산화 메카니즘, 그리고 식물성 phenolic compounds들의 항산화능 등에 대하여 차례로 살핀다. 특히, 우리가 일상적으로 섭취하고 있는 식품에서의 이들 물질과 그들의 항산화성에 대한 최근 연구결과들을 중심으로 고찰한다.

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Effect of Phenolic Acids on Inhibition of Browning of Maillard Reaction Model Solutions (Phenolic acid가 Maillard 반응 모델액의 갈변억제에 미치는 영향)

  • Kwak, Eun-Jung;Lim, Seong-Il
    • Korean Journal of Food Science and Technology
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    • v.39 no.1
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    • pp.20-24
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    • 2007
  • The effects of phenolic acids on inhibition of browning by the Maillard reaction were investigated with a glucose-glutamic acid model for doenjang with citric acid as the antibrowning agent and phenolic acid as its synergist. Five phenolic acids, cinnamic, coumaric, caffeic, hydroxybenzoic, and protocatechuic acids, were used. In order to investigate the antibrowning capacity, 0.1M glucose, 0.1M glutamic acid, 50mM citric acid, and 1mM phenolic acid were dissolved in 1M phosphate buffer (pH 7.0), heated at $50^{\circ}C$ for 24hr in the presence of 0.2mM $FeCl_{2}$, and stored at $4^{\circ}C$ or $30^{\circ}C$ for four weeks. Phenolic acid addition more efficiently inhibited browning during storage at $30^{\circ}C$ than at $4^{\circ}C$, without changes in pH. Hydroxybenzoic acid was the most efficient and increased the antibrowning capacity by 13% compared to sample without phenolic acids. Although caffeic and protocatechuic acids inhibited most the formation of 3-deoxyglucosone or fluorescence, they increased browning by forming colored complexes between two hydroxy groups of phenolic acids and iron ions. Hydroxybenzoic acid will be able to be a useful synergist of citric acid, an antibrowning agent in doenjang, since it is permitted for doenjang.