• 임산에너지
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• 제23권1호
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• pp.45-68
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• 2004

The word of lignin is derived from the Latin word 'ligum' meaning wood. Lignin is complex polymer consisting of coniferyl alcohol, sinapyl alcohol and p-coumaryl alcohol unit and has an amorphous, three dimensional network structure which is hard to be hydrolyzed by acid. Lignin is found in the cell wall of plants lignified. The mode of polymerization of these alcohols in the cell wall lead to a heterogeneous branched and cross-linked polymer in which phenyl propane units are linked by carbon-carbon and carbon-oxygen bonds. This polymerization of precursors, p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol to lignin is formed by enzymic dehydrolyzation. The reaction is initiated by an electron transfer which results in the formation of resonance-stabilized phenoxy radical. The combination of these radicals produces a variety of dimers, trimers and oligomers and so on. Lignin research has been divided into basic and practical application field. The basic studies contains biosynthesis, chemical structure, distribution in the cell wall and reactivity by reductants, oxidants and organic solvents. The application research will be approached the reaction of lignin in various pulp making involving pulp bleaching and its effect on pulp qualities. Lignin also will be studied for the production of fine chemicals, polymer products and the conservation into an energy source like petroleum oil because the amount of lignin produced in pulp making process is more than 51,000,000 tons per year in the world. Both basic and application research must lay emphasis on the development for the utilization of lignin and the pulping process. But these researches can not be completed without understanding lignin structure containing functional groups. Therefore, this paper was focused on the review of lignin formulation which has been studied since 1948 in chronological order. This review was based on monomers, dimers, trimers and tetramers of phenyl propane unit structures which were isolated and identified by different methods from various wood.ious wood.

• 한국수산과학회지
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• 제48권5호
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• pp.768-775
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• 2015

Seasonal variability in the marine seaweed community structure was examined in the intertidal zones at nine study sites in Hallyeohaesang National Park, on the southern coast of Korea from March to October 2014. A total of 145 seaweeds were indentified, comprising 15 green, 41 brown and 89 red algae. Coarsely branched seaweeds were the dominant functional group, comprising 58.95% in species number, whereas filamentous, sheet, thick leathery, crustose and jointed calcareous forms comprised 2.63-17.72% each. The seaweed biomass averaged 358.00 g dry wt/m² and it was maximal at Somaemuldo (847.64 g dry wt/m²) and minimal at Gamam (56.51 g dry wt/m²). Based on biomass, the dominant and subdominant seaweeds were Ulva australis at Gamam, Sargassum thunbergii at Sangju, Ulva australis and S.fulvellum at Neukdo, S.horneri at Dala-Bijindo-Somaemuldo, S. thunbergii at Dapo, and Corallina pilulifera at Songdo. Community indices were as follows: dominance index (DI), 0.43-0.71; richness index (R), 8.26-16.50; evenness index (J'), 0.36-0.54; and diversity index (H'), 1.57-2.19. In conclusion, we found that both biomass and the community structure of seaweeds in Hallyeohaesang National Park were similar to those in other studies of the Southern Sea along the Korean peninsula, and that Hallyeohaesang National Park is a relatively favorable habitat for seaweeds. Future studies should examine the changes in seaweed composition and biomass as they relate to climate change and environmental pollution.

• BMB Reports
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• 제33권3호
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• pp.195-201
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• 2000

A human gene has been reported that may encode the enzyme acetohydroxyacid synthase. Previously this enzyme was thought to be absent from animals although it is present in plants and many microorganisms. In plants, this enzyme is the target of a number of commercial herbicides and the use of these compounds may need to be reassessed if the human enzyme exists and proves to be susceptible to inhibition. Here we report the construction of several plasmid vectors containing the cDNA sequence for this protein, and their expression in Escherichia coli. High levels of expression were observed, but most of the protein proved to be insoluble. The small amounts of soluble protein contained little or no acetohydroxyacid synthase activity. Attempts to refold the insoluble protein were successful insofar as the protein became soluble. However, the refolded protein did not gain any acetohydroxyacid synthase activity. In vivo complementation tests of an E. coli mutant produced no evidence that the protein is active. Incorrect folding, or the lack of another subunit, may explain the data but we favor the interpretation that this gene does not encode an acetohydroxyacid synthase.

• Bulletin of the Korean Chemical Society
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• 제24권8호
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• pp.1207-1210
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• 2003

The effect of solvent structure on the slope in the plot of ln K vs. solute carbon number was examined. It was found that the free energy of methylene group transfer from the gas phase into a solvent was always negative and that the absolute magnitude of interaction free energy between the methylene group and the solvent was always larger than the absolute magnitude of cavity formation free energy of the methylene group in the solvent. Thus, the slope in the plot of ln K vs. solute carbon number was always positive and its value decreases with increase of solvent polarity since the cavity formation energy of the CH₂ unit increases with increase of solvent polarity while the dispersive interaction energy of the CH₂ unit is virtually invariant. We also examined the effect of sequential addition of CH₂ unit to a solvent molecule upon ln K for three homologous series of solvents: n-alkanes, n-alcohols, and n-nitriles. Characteristic trends in the plots of ln K vs. solvent carbon number were observed for individual solvent groups. A decrease of ln K with solvent carbon number was observed for n-alkanes. An abrupt increase in ln K followed by levelling off was observed for n-alcohols while a final slight decrease in ln K after an abrupt increase followed by rapid levelling off was noted for n-nitriles. All of theses phenomena were found related to variation in cavity formation energy. It was clearly shown that a structural change of a polar solvent by sequential addition of CH₂ units causes an abrupt polarity decrease initially, then gradual levelling off, and finally, conversion to a virtually nonpolar solvent if enough CH₂ units are added.

• Journal of the Korean Wood Science and Technology
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• 제10권2호
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• pp.12-21
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• 1982

Red pine and Japanese larch (Larix leptolepis Gordon) grown in Korea have been the main species of coniferous resources in Korea. Especially, planting area of Japanese larch has been increased continueously in the recent years due to its superior plant type and rapid growth rate and its stocks reached approximately 4.32 million cubic meters at the present time. Although many research works have been done for the utilization of the larch wood in various ways, still many problems are existed in its chemical applications due to a large proportion of soluble extractives. In this study, chemical composition of larch extractives and chemical structure of its major component were analyzed. In order to identify the basic structure of major component, gas-liquid chromatography for separation of some completely methylated alditols as their acetates on a 3% - ECNSS-M on Gas Chrom Q. column was used. Proportion of extractives of Japanese larch wood was higher than that of other conifers and major component of the soluble extractives was arabinogalactan, a schematic structural formula which was presented in Figure 2. The molar ratio of arabinose and galactose was 1:4.5. The main chain of arabinogalactan was composed of 1,3 linked ${\beta}$-D-galactopyranose residues, each of which carried a side chain, attached to the C-6 positions. The exact nature of all of the side chains is not known, but the majority of these side chain was composed of 1, 6 linked ${\beta}$-D-galactopyranose residues, with 2~3 such units present per average chain. Some of the galactose units in the main chain had a residue of 3 - 0 - ${\beta}$-L-arabinopyranosyl-L-arabinofuranose. In addition, a few terminal residues of D-glucuronic acid also was confirmed, attached to C-6 position of the D-galactopyranose residue. It could concluded that the main structure of highly branched arabinogalactan from Japanese larch extractive was essentially the same as those of the other larch species.

• 한국수산과학회지
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• 제26권1호
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• pp.49-62
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• 1993

본 조사는 남해의 10개 도서의 조간대 해조군집의 구조와 특성을 조사하였다. 그 결과 군집의 구조는 상, 중, 하부의 뚜렷한 층위구조로 구성되고, 상부와 중부의 중요종은 조사지간에 매우 유사하였다. 하부의 중요종은 지역간에 차이가 있고, 다양한 종에 의해 대표되었다. 상부의 대표종은 막상 또는 사상형의 Gloiopeltis spp., Gelidium divaricatum, Porphyra suborbiculata, Nemalion vermiculare였으며, 분포범위는 해조분포 상한에서 따개비와 홍합류 층의 하한이었다. 중부의 대표종은 Corallina pilulifera, Chondria crassicaulis, Hizikia fusiformis이며, 분포범위는 평균해면 부근이었다. 하부의 범위는 중부의 하한에서 기준면까지이고, Sargassum sagamianum, Laurencia spp., Symphyocladia latiuscula, Chondrus spp., Pachymeniopsis lanceolata, Gigartina spp.가 조사지간에 공통성이 높은 중요종으로 나타났다.

• 한국수산과학회지
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• 제48권6호
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• pp.969-976
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• 2015

Macroalgal community structure was seasonally examined at Hakampo (Taean) in western coast of Korea from February 2007 to October 2010. Also, the effects of "Hebei Spirit" oil spill on the seaweed community structure were evaluated. A total of 101 macroalgal species were identified, comprising 12 green, 18 brown and 71 red algae. Species richness ranged 58-65 species with maximal in 2008 and minimal in 2009. Seaweed biomass ranged $75.81-102.06g\;dry\;wt./m^2$ (mean, $88.78g/m^2$) with maximal in 2008 and minimal in 2010. Vertical distribution from the high to low intertidal zone was Neorhodomela aculeata and Polyopes affinis; Corallina pilulifera and Chondrus ocellatus; Sargassum thunbergii and Ulva australis. Coarsely-branched seaweeds comprised the highest proportion of biomass ($37.17g/m^2$, or 41.86% of the total biomass) and ecological state group I (ESG I) seaweed biomass was between 81.67-85.44%. Also, ephemeral macroalgae including Ulva species sharply increased in species number and biomass within 1-2 year from the "Hebei Sprit" oil spill in the mid and low intertidal zone. Hakampo rocky shore is still good condition as evaluated based on macroalgal species number, biomass, and composition in functional form and ESG I seaweeds.

• Applied Microscopy
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• 제33권4호
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• pp.325-333
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• 2003

왕거미과 산왕거미(Araneus ventricosus)의 심관과 심근세포의 미세구조적 특성을 주사형 및 투과형 전자현미경으로 관찰하였다. 거미의 심관은 복부마디의 등쪽에 분포되어 있고, 심외막과 심근층으로 구성되어 있었다. 심근층의 근섬유들은 종축을 중심으로 나선상의 배열을 이루고 있었고, 내막이 없이 혈림프에 직접 노출되는 구조를 이루고 있었다. 심관의 외부 표면에서는 3쌍의 심문이 형성되어 있었고, 내강에서는 원형질혈구와 과립혈구, 그리고 편도혈구 등 다양한 유형의 혈구들이 관찰되었다. 특히 심관의 내강을 향해 돌출된 심근돌기 주위에서는 편도혈구들이 대부분을 차지하고 있었다. 편도혈구의 세포질에는 유리 리보조옴이 산재되어 있었고 핵에는 이질염색질과 인이 발달되어 있었으나, 심근층 조직과의 특이한 연접은 관찰되지 않았다. 심근층에는 횡문이 형성되어 있었고, Z-line을 중심으로 근절의 구조를 이룬 근원섬유의 주위에서는 미토콘드리아와 근소포체가 풍부하게 함유되어 있었다. 심관의 배면을 따라 뻗은 신경절의 축삭들이 심근세포와 신경근육간 연접부를 형성하고 있음이 관찰되었다.

• 대한화학회지
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• 제40권7호
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• pp.509-514
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• 1996

3차원 금속착체 포접화합물 $Cd(pn)Ni(CN)_4{\cdot}0.5NO_2C_6H_5$(pn: 1,2-diaminopropane=propylenediamine)은 사방정계 공간군 $Pn2_1$a로, a=13.868(5), b=26.591(4), c=7.840(1)${\AA}$, V=2891(1)${\AA}^3$, Z=4이며, 28000개의 독립적인 회절반점에 대한 R값은 0.054이다. 이 포접화합물의 host구조는 가지 달린 지방족 guest 분자를 포접한 포접화합물의 host 구조(T-type)와 같다. Nitrobenzene guest 분자는 T-type의 nodal형 턴넬속에 안정하게 포접되는데, 이는 node 위치체 pn-amino group이 놓이고, antinode 위치에 부피가 큰 방향조 고리가 놓이며, 이들 사이에 극성인 nitro group이 있기 때문이다. 턴넬형의 포접골간을 갖는 금속착체 $Cd(pn)Ni(CN)_4$의 host 구조가 가지 달린 방향족 guest 분자를 포접하고 있다.

• 한국가스학회지
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• 제19권3호
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• pp.44-48
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• 2015

중회귀분석을 사용하여 혼합연료가스의 탄화수소 이슬점(DT)을 구하였다. QSDR(Quantitative Structure Dew-point Relationship)에서 주요한 설명인자는 혼합연료가스 중의 평균탄소수(CN : carbon number)와 혼합연료가스 중의 가지달린 이성질체 비율(BI : the ratio of the branched isomer)이었다. 혼합연료가스의 압력을 100 kPa ~ 500 kPa로 변화시키며 QSDR을 수행한 결과는 다음과 같다. $$DT(^{\circ}C)=-683.1+1224.98CN-898.01CN^2+308.58CN^3-49.56CN^4+3.02CN^5-12.42BI$$ (at 100 kPa, $$R_{adj}{^2}=0.99$$) (1) $$DT(^{\circ}C)=-745.2+1351.66CN-978.1CN^2+332.7CN^3-52.96CN^4+3.20CN^5-12.84BI$$ (at 200 kPa, $$R_{adj}{^2}=0.99$$) (2) $$DT(^{\circ}C)=-795.4+1457.1CN-1051.1CN^2+357.53CN^3-57.07CN^4+3.46CN^5-13.10BI$$ (at 300 kPa, $$R_{adj}{^2}=0.99$$) (3) $$DT(^{\circ}C)=-868.1+1608.4CN-1156.0CN^2+393.38CN^3-63.06CN^4+3.85CN^5-13.39BI$$ (at 500 kPa, $$R_{adj}{^2}=0.99$$) (4) 혼합연료 중의 평균탄소수의 값이 감소하거나 비점이 낮은 가지달린 이성질체의 비율이 증가할 때 탄화수소 이슬점이 낮아진다. 이 결과는 중회귀분석에 의하여 얻어진 탄화수소이슬점과 상용프로그램 VMGSim을 통하여 계산된 값과 유사하였다.