• The Korean Journal of Ecology
• /
• v.23 no.3
• /
• pp.281-291
• /
• 2000

The objectives of this study were to classify quantitatively vegetational types of P. densiflora for. erecta forest. The results were summarized as follows. 1) According to the canonical correspondence analysis(CCA), variables such as topography, altitude, available P/sub 2/O/sub 5/, and Mg/sup 2＋/were highly correlated on three axes. Based on the correlations between vegetation units and environmental factors, Rhododendron micranthum community tended to be more distributed in the such situations of high altitude, upper topography, high C/N ratio, low level of Mg/sup 2＋/and Ca/sup 2＋/. Vaccinium koreanum community tended to be more distributed in the such conditions of high altitude, upper topography, high level of Ca/sup 2＋/and Ma/sup 2＋/. 2) According to the results of importance value analysis, Tree layer and Subtree layer in study areas showed high Ⅳ along with P. densiflora for. erecta, Quercus mongonlica, Q. variabilis, Q. serrata, Fraxinus rhychophylla and shrub layer indicated that Ⅳ of P. densiflora for, erecta in Sokwang-ri area was higher than those of the other areas. Therefore, it was considered that P. densiflora for. erecta forest of Sokwang-ri area could be naturally regenerated. 3) According to results of species diversity, the species diversity of Uljin region showed the least low value as 0.6622, other regions appeared about 0.7. In the diversity by vegetation types, Acer pseudosieboldianum community showed high value. 4) According to the analysis of community similarity, Sokwang-Ri region was lowly correlated with Uljin region, while the index among the other areas appeared above 0.6. 5) According to the analysis of interspecific association, it was divided into 2 groups. The species of first group were mainly involved in character species, and the species of second group were involved in differential species groups.

• Journal of Bio-Environment Control
• /
• v.12 no.4
• /
• pp.190-194
• /
• 2003

This study was carried out to investigate the effect of several subtrates on the growth of cucumber and tomato seedlings. Cucumber and tomato seeds were sown in plug trays that were filled with eight differenct kinds of substrates. One of them was filled with recycled rockwool by 100%. The other six were mixed with used rockwool media:several ratios of recycled rockwool+peatmoss (1:1, 1:2, 1:3, v/v) and recycled rockwool+chestnut wood ships (1:1, 1:2, 1:3, v/v), and the last was 100% chestnut wood chips. The growth of cucumber and tomato seedlingsin 72 plug tray was better in recycled rockwool+peatmoss (1:2, v/v) substrates that the others tested. CEC 9cation exchange capacity) and EC was a little higher in mixed substrates that blended with organic media. But 100% chestnut wood chips and mixed ones with recycled rockwool inhibited severely the growth of seedlings, especially in tomatos. Therefore, it is suggested that the recycled rockwool be capable of utilization to raise seedlings of cucumber and tomato.

• Korean Journal of Environmental Biology
• /
• v.24 no.1 s.61
• /
• pp.46-52
• /
• 2006

The mercury is among the most highly bioconcentrated toxic trace metals. Many national and international agencies and organisations have targeted mercury for the possible emission control. The mercury toxicity depends on its chemical form, among which alkylmercury compounds are the most toxic. A human cervix uterus cancer cell line HeLa cells was employed to investigate the effect of the toxic heavy metal mercury (Hg) and ionizing radiation. In the in vitro comet assays for the genotoxicity in the HeLa cells, the group of Hg treatment after irradiation showed higher DNA breakage than the other groups. The tail extent moment and olive tail moment of the control group were $4.88{\pm}1.00\;and\;3.50{\pm}0.52$ while the values of the only Hg treatment group were $26.90{\pm}2.67\;and\;13.16{\pm}1.82$, respectively. The tail extent moment and olive tail moment of the only 0.001, 0.005, 0.01 Hg group were $12.24{\pm}1.82,\;8.20{\pm}2.15,\;20.30{\pm}1.30,\;12.26{\pm}0.52,\;40.65{\pm}2.94\;and \;20.38{\pm}1.49$, respectively. In the case of Hg treatment after irradiation, the tail extent moment and olive tail moment of the 0.001, 0.005, 0.01 Hg group were $56.50{\pm}3.93,\;32.69{\pm}2.48,\;62.03{\pm}5.14,\;31.56{\pm}1.97,\;72.73{\pm}3.70\;and \;39.44{\pm}3.23$, respectively. The results showed that Hg induced DNA single-strand breaks or alkali labile sites as assessed by the Comet assay. It is in good agreement with the reported results. The mercury inhibits the repair of DNA. The bacterial formamidopyrimidine-DNA glycosylase (Epg protein) recognizes and removes some oxidative DNA base modifications. Enzyme inactivation by Hg (II) may therefore be due either to interactions with rysteine residues outside the metal binding domain or to very high-affinity binding of Hg (II) which readily removes Zn (II) from the zinc finger.

• Applied Biological Chemistry
• /
• v.20 no.1
• /
• pp.33-42
• /
• 1977

Asparagine biosynthesis by soybean sprouts grown under the dark conditions has been demonstrated. The amount of free asparagine synthesized in ten day-old soybean sprouts increases to 22.7% on the dry weight base. The effects of nitrogen compounds such as $NH_4Cl,\;(NH_4)_2SO_4$ and urea on asparagine synthesis during the sprouting were examined and the results showed that urea was more effective than other two compounds. Glutamine-dependent asparagine synthetase was partially purified (8.6 folds) through ammonium sulfate fractionation, followed by Sephadex G-150 gel filtration. The enzyme was very labile and required protection by thiol groups or high level of glycerol. The mixture of ATP and $Mg^{++}$ ion also stabilized the enzyme activity. The enzyme utilized glutamine more effectively than ${NH_4}^+$ as an amide donor for the formation of asparagine. The enzyme required L-aspartate (Km=3.1 mM), L-glutamine, ATP and $Mg^{++}$. It showed pH optimum of 7.5 and catalyzed the formation of ${\beta}-aspartyl$ hydroxamate in the presence of L-aspartate, ATP, $Mg^{++}$ and $NH_2OH$ in the reaction mixture.

• KSBB Journal
• /
• v.15 no.1
• /
• pp.49-54
• /
• 2000

Bioluminescence of Photobacterium phosphoreum has been used for the detection of pollutants in the environment. Immobilization method was used to maintain the stability of bioluminescence of P. phosphoreum. The carboxymethylcellulose was investigated to find out whether it was suitable for the immobilization of P. phosphoreum as a matrix without disturbing the bioluminescence emission. A maintenance of bioluminescence was determined from the P. phosphoreum immobilized on the various concentrations of carboxymethylcellulose. A relatively high bioluminescence intensity was shown with immobilized cells on 1%(w/v) carboxymethylcellulose. The effect of carboxymethylcellulose concentrations on the sensitivity of Crcompounds including $Na_{2}CrO_{4}$, $K_{2}CrO_{4}$, $CrO_{3}$, CrK$(SO_4)_{2}$ and $CrCl_{3}$ to the bioluminescence intensity. The calculated $EC_{50}$ showed that the linear relations between such substances and bioluminesence intensity were established.

• Membrane Journal
• /
• v.31 no.2
• /
• pp.87-100
• /
• 2021

With a striking increase in the level of contamination and subsequent degradations in the environment, detection and monitoring of contaminants in various sites has become a crucial mission in current society. In this review, we have summarized the current research areas in membrane-based colorimetric sensors for trace detection of various molecules. The researches covered in this summary utilize membranes composed of cellulose fibers as sensing platforms and metal nanoparticles or fluorophores as optical reagents. Displaying decent or excellent sensitivity, most of the developed sensors achieve a significant selectivity in the presence of interfering ions. The physical and chemical properties of cellulose membrane platforms can be customized by changing the synthesis method or type of optical reagent used, allowing a wide range of applications possible. Membrane-based sensors are also portable and have great mechanical properties, which enable on-site detection of contaminants. With such superior qualities, membrane-based sensors examined in the researches were used for versatile purposes including quantification of heavy metals in drinking water, trace detection of toxic antibiotics and heavy metals in environmental water samples. Some of the sensors exhibited additional features like antimicrobial ability and recyclability. Lastly, while most of the sensors aimed for a detection enabled by naked eyes through rapid colour change, many of them investigated further detection methods like fluorescence, UV-vis spectroscopy, and RGB colour intensity.

• Korean Journal of Food Science and Technology
• /
• v.29 no.3
• /
• pp.446-451
• /
• 1997

The primary alcohol groups of four kinds of polysaccharides (com starch, rice starch, sweet potato starch, and cellulose), with different structures and water solubilities, were oxidized to carboxyl groups using 2,2,6,6-tetramethyl-1-piperidine oxoammonium ion (TEMPO) at $25^{\circ}C$. The optimum pH, TEMPO content, and NaBr content for the TEMPO/hypobromite-catalyzed oxidation of the polysaccharides were $10.5{\sim}11.0$, 10 mmol/mol primary alcohol, and 0.49 mmol/mol primary alcohol, respectively. The oxidation degree for the primary alcohol group was more than 90% for all four kinds of the polysaccharides. The oxidation process greatly increased the water solubility of the polysaccharides. Water-insoluble polysaccharide such as cellulose became water-soluble to the extent of 8.42% (w/v). And also, the polysaccharides with very low water solubility (less than 0.10% (w/v)) such as com starch, rice starch, and sweet potato starch had high water solubility of approximately 45%(w/v). The gel-forming abilities with calcium ion were determined. The oxidized polysaccharides are new anionic polymers with unique structures that could have application as gums, gels, and films.

• The Korean Journal of Mycology
• /
• v.32 no.2
• /
• pp.142-144
• /
• 2004

The effect of hot water and methanol extracts of 9 species from Korean mushrooms (Fomitopsis pinicola, Fomitella traxinea, Codyceps militaris, Phellinus linteus, Coriolus versicolor, Sparassis crispa, Ganoderma lucidum, Fomes fomentarius, Agaricus blazei) on the growth of Helicobacter pylori were examined using a Mueller-Hinton agar diffusion method. Hot water ($121^{\circ}C$) extracts from fruit bodies of F. traxinea, C. militaris, P. linteus, C. versicolor and F. pinicola showed $10{\sim}15\;mm$ inhibition zone against H. pylori. Methanol extracts of F. pinicola showed 44 mm inhibition zone, but another extracts showed no inhibition. Early fractions of DEAE-Sephadex A-25 column chromatography of methanol extracts from F. pinicola showed high inhibition activity against H. pylori.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.409-409
• /
• 2012

최근 나노크기의 미세구조 가공기술이 발달함에 따라 다양한 응용을 위한 나노소재/구조가 활발히 연구 되고 있다[1]. 그 중에서 실리콘 나노선은 태양전지, 메모리, 트랜지스터 그리고 광 공진기에 쓰일 수 있는 소재로서 기존의 실리콘 가공기술을 바로 사용할 수 있을 뿐 아니라[2], 비용 면에서 탁월한 잇점이 있기 때문에 주목 받고 있는 소재이다. 실리콘 나노선의 물리적 특성을 연구하기 위한 많은 연구가 진행되었지만, 매우 작은 크기와 높은 표면적-부피비율로 인해 생긴 독특한 특징을 완전히 이해하기에는 아직 부족한 점이 많다. 실리콘 나노선의 전류-전압특성에 영향을 미치는 요소는 도핑농도, 표면상태, 채널의 크기 등으로 다양한데, 이번 연구에서는 실리콘 나노선의 표면환경이 공기와 물 두 종류로 매질에 접하고 있을 경우에 대하여 각각 전류-전압을 측정하였다. 물이 공기와 다른 점은 크게 두 가지로 볼 수 있다. 첫째로 물의 경우에는 물에 용해된 수소이온과의 화학반응을 통하여 실리콘 표면전하가 유도되며 pH 값에 민감하게 변화한다. 둘째로 물의 유전율은 공기의 80배로서 표면부근에서의 전기장분포가 많이 왜곡된다. 이를 위하여 SOI를 기반으로 채널길이 $5{\mu}s$, 두께 40 nm, 너비 100 nm인 실리콘 나노선을 일반적인 반도체공정을 사용하여 제작하였다. 나노선의 전기적 특성 실험은 Semiconductor Parameter Analyzer (Agilent, 4155C)를 사용하여 전류-전압특성을 표면 상태를 변화시키면서 측정하였다. 실험을 통해 실리콘 나노선은 물과 공기 두 가지 표면환경에 따라 전류-전압특성이 확연히 변화하는 것을 볼 수 있었다. 동일한 전압 바이어스에서 표면에 물이 있을 때가 공기 있을 때 보다 훨씬 증가한 전류를 얻을 수 있었고(3V에서 약 2배), 비선형적인 전류-전압특성이 나타남을 관찰하였다. 본 발표에서는 이러한 실험결과를 표면에서의 전하와 정전기적인 효과로서 정성적으로 설명하고, 전산모사결과와 비교분석 하고자 한다.

• Microbiology and Biotechnology Letters
• /
• v.6 no.4
• /
• pp.149-153
• /
• 1978

A strain of Streptomyces sp producing chitinase was isolated from soil and its cultural condition and some properties of this enzyme were investigated. When 0.375 per cent of glucose was added to basal medium, this organism produced the most quantities of this enzyme after shaking culture at 3$0^{\circ}C$ for 48 hrs., while the production of the enzyme was repressed at the more concentration of glucose than that. The enzyme had a optimal pH of 7.0, optimal temperature of 5$0^{\circ}C$ and the activity of that was not decreased by heat treatment for 20 minute at 7$0^{\circ}C$. And then the activity was increased by Co$^{2+}$ but was slightly inhibited by Hg$^{2+}$, Ni$^{2+}$, Pb$^{2+}$.EX> 2+/.