• Polymer(Korea)
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• v.39 no.3
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• pp.388-393
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• 2015

Low molecular weight species were extracted from PC and SAN by a solvent extraction method in order to investigate the effect of low molecular weight species on interfacial tension and affinity between PC and SAN. From the analysis of molecular weight distribution by the GPC, it was confirmed that the low molecular weight species were effectively eliminated by the solvent extraction. Interfacial tension measurements and morphological observation were carried out with the PC and SAN of which the low molecular weight species were extracted. Interfacial tension was increased and the infinity was decreased for the extracted PC and SAN pair. This result implied that the low molecular weight species play a role as a compatibilizer between two polymers. Among two polymers, low molecular weight SAN contributes more in the compatibilization. Thus, it is favorable to use SAN containing a larger amount of low molecular weight species in fabrication of PC/ABS blend.

• Korean Journal of Plant Resources
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• v.19 no.4
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• pp.555-561
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• 2006

This study was carried out to investigate the suitable place for growth by analyzing the ecological environment of multi-use tree species to be spontaneous in Chungbuk Province, and derive the suitable place for forestation. At the test of the independence of multi-use tree species, as the significant correlation of the other tree species except Quercus acutissima - Zanthoxylum schinifolium was different by the survey location, it is concluded that the share relation of the ecological niche among tree species is largely influenced not only by the affinity of tree species but the growth environment. As the result of the correlation analysis between environment factors and tree clusters, it was analyzed that tree clusters were much influenced by the topography and the altitude among the variable environment factors; the topography, altitude, the direction of hillside, the slope and the number of tree species appearing. It was investigated that the cluster of Acer mono - Betula costata was distributed to the valley from low hillside to have high altitude, and the clusters of Kalopanax pictus - Ulmus davidiana var. japonica and Fraxinus rhynchophylla - Rhus trichocarpa were sporadically distributed to broad location because their geographical adaptation powers are high.

• Archives of Pharmacal Research
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• v.25 no.6
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• pp.807-816
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• 2002

Dihydrofolate reductases (DHFR) of human, Candida albicans and E. coli were docked with their original ligands of X-ray crystal complex using QXP (Quick eXPlore), a docking program. Conditions to reproduce the crystal structures within the root mean square deviation (rmsd) of 2.00 $\AA$ were established. Applying these conditions, binding modes and species-specificities of a novel antibacterial compound, $N^4-(2-acetoxyethoxymethyl)-2-acetylpyridine$ thiosemicarbazone (MTSC), were studied. As the results, the docking program reproduced the crystal structures with average rmsd of six ligands as 0.91 $\AA$ ranging from 0.49 to 1.45 $\AA$. The interactions including the numbers of hydrogen bonds and hydrophobic interactions were the same as the crystal structures and superposition of the crystal and docked structures almost coincided with each other. For AATSC, the results demonstrated that it could bind to either the substrate or coenzyme sites of DHFR in all three species with different degrees of affinity. It confirms the experimentally determined kinetic behavior of uncompetitive inhibition against either the inhibitor or the coenzyme. The docked MTSC overlapped well with the original ligands and major interactions were consistent with the ones in the crystal complexes. The information generated from this work should be useful for future development of antibacterial and antifungal agents.

• Fisheries and Aquatic Sciences
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• v.21 no.8
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• pp.28.1-28.12
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• 2018

Intertidal macroalgae are exposed to many abiotic stress factors, and they must regularly react to changes in their environment. We used RNA-seq to describe how Porphyra umbilicalis (Rhodophyta) changes gene expression patterns to interact with different habitats. Tissue samples were taken from a typical habitat along the open-coast of the Northwest Atlantic, as well as from a rare, atypical habitat in an estuarine tidal rapid environment. Differential gene expression analyses suggest that pathogic bacteria and viruses may be a significant factor influencing the transcriptome in the human-impacted estuarine environment, but the atypical habitat does not necessarily induce more stress in Porphyra umbilicalis growing there. We found genes related to nitrogen transport are over-expressed in tissue from the open-coastal site compared to those from the estuarine site, where environmental N levels approach hypertrophic levels. Low N levels impede growth, but high levels are toxic to cells, and we use qPCR to show this species regulates expression of a putative high-affinity $NH_4{^+}$ transporter under low and high N conditions. Differences in expression of this transporter in these habitats appear to be inherited from parent to offspring and have general implications for adaptation to habitat in other species that are capable of asexual reproduction, as well as more specific implications for this species' use in aquaculture.

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.250-254
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• 1998

Harmful micro algae isolated from Korean coastal waters, were tested with FITC-conjugated lectins and observed by epifluorescent microscopy to distinguish each other. Strain-specific sugar composition at the cell surface was suggested by the affinity of lectins to different microalgae. The micro algae Cochlodinium polykrikoides (CP-1) and Gymnodinium $A_3\;(GA_{3-1}\;1)$, are morphologically similar, but exhibited different binding activity with the lectins ECA, HPA and WGA. In Peridiniales, the micro alga Alexandrium tamarense (AT) bound HPA and WGA, but Scrippsiella trochoidea (ST-1) did not bind those lectins. Three species of Prorocentrum also exhibited different binding specificity with HPA, PHA and SBA. A non­toxic Korean isolate of Heterosigma akashiwo (HA-2) bound ConA, PEA and UEA. These results suggest that lectins are useful in discriminating morphologically similar species, as well as different species or strains within the same genus.

• Horticultural Science & Technology
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• v.28 no.3
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• pp.497-506
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• 2010

This study intended to investigate the environmental factors including soil and vegetation in order to better understand the environmental and ecological characteristics of ten different habitats of $Hanabusaya$ $asiatica$. These habitats, according to investigations, are mostly located on the slopes of mountains facing north at an altitude of 580 m to 1,396 m above sea level with angles of inclination ranging from 5 degrees to 80 degrees. A total of 146 vascular plant taxa are identified in 32 quadrates of the ten habitats. The importance value of $H.$ $asiatica$ is 8.87%, and 5 highly ranked species such as $Carex$ $siderosticta$ (8.67%), $Ainsliaea$ $acerifolia$ var. $subapoda$ (7.10%), $Calamagrostis$ $arundinacea$ (6.79%), $Athyrium$ $yokoscense$ (5.33%), $Astilbe$ $rubra$ (3.11%) are considered to be an affinity with $H.$ $asiatica$ in their habitats. Dominant species of woody plants in ten habitats are represented as $Quercus$ $mongolica$ in tree layer (T1), $Acer$ $pseudo$-$sieboldianum$ in subtree layer (T2), $Rhododendron$ $schlippenbachii$ and $Tripterygium$ $regelii$ in shrub layer (S). The degree of their average species diversity is 1.30, and that of dominance and evenness are 0.08 and 0.88, respectively. The type of soil is sandy loam, loam and loamy sand, and the average field capacity of soil is 23.95%. Their average organic matter is 12.28%, soil pH 5.79, and available phosphorus is 25.48%. Correlation coefficients analysis based on environmental factors, vegetation and soil analysis shows that the coverage of tree layers is correlated with richness, diversity, dominance, evenness and coverage of $H.$ $asiatica$.

• Journal of Ecology and Environment
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• v.44 no.4
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• pp.241-255
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• 2020

Background: The stem exclusion stage is a stage of forest development that is important for understanding the subsequent understory reinitiation stage and maturation stage during which horizontal heterogeneity is formed. Over the past 11 years (2009-2019), we observed a deciduous broad-leaved forest in the Albongbunji Basin in Ulleungdo, South Korea in its stem exclusion stage, where Fagus engleriana (Engler's beech) is the dominant species, thereby analyzing the changes in the structure (density and size distributions), function (biomass and species richness), and demographics. Results: The mean stem density data presented a bell-shaped curve with initially increasing, peaking, and subsequently decreasing trends in stem density over time, and the mean biomass data showed a sigmoidal pattern indicating that the rate of biomass accumulation slowed over time. Changes in the density and biomass of Fagus engleriana showed a similar trend to the changes in density and biomass at the community level, which is indicative of the strong influence of this species on the changing patterns of forest structure and function. Around 2015, a shift between recruitment and mortality rates was observed. Deterministic processes were the predominant cause of tree mortality in our study; however, soil deposition that began in 2017 in some of the quadrats resulted in an increase in the contribution of stochastic processes (15% in 2019) to tree mortality. The development of horizontal heterogeneity was observed in forest gaps. Conclusions: Our observations showed a dramatic shift between the recruitment and mortality rates in the stem exclusion stage, and that disturbance increases the uncertainty in forest development increases. The minor changes in species composition are likely linked to regional species pool and the limited role of the life-history strategy of species such as shade tolerance and habitat affinity. Our midterm records of ecological succession exhibited detailed demographic dynamics and contributed to the improvement of an ecological perspective in the stem exclusion stage.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1337-1353
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• 2010

This study intended to investigate environmental factors including soil and vegetation in order to understand the environmental and ecological characteristics of 12 different habitats of Iris odaesanensis. These habitats, according to investigations, are mostly located at elevation of 280 m to 1,555 m with angles of inclination ranging from 2 degree to 30 degrees. A total of 273 vascular plants are identified in 23 quadrates of 12 habitats. Dominant species of woody plants in 12 habitats are represented as Quercus mongolica in the tree layer (T1) and the subtree (T2) layer, and Lespedeza maximowiczii, Lindera obtusiloba, Rhododendron schlippenbachii in the shrub (S) layer. The importance value of Iris odaesanensis is 9.65%, as regards the herbaceous layer, and 6 highly ranked species such as Carex siderosticta (3.92%), Meehania urticifolia (2.67%), Spodiopogon cotulifer (2.58%), Aconitum pseudolaeve (2.51%), Carex bostrychostigma (2.28%) and Disporum smilacinum (2.09%) are considered to be an affinity with Iris odaesanensis in their habitats. The degree of their average species diversity is 1.32, and that of dominance and evenness are 0.08 and 0.89, respectively. The type of soil is sandy loam and loam, and the average field capacity of soil is 28.31%. Their average organic matter is 16.71%, soil pH 5.29, and available phosphorus is 9.29%. Correlation coefficients analysis based on environmental factors, vegetation and soil analysis shows that the coverage of Iris odaesanensis is correlated with pH and dominance, and species richness is positive related with species diversity.

• Journal of Korean Society of Forest Science
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• v.65 no.1
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• pp.60-67
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• 1984

This study was identified 6 species of the genus Acer in Korea by the method of thin layer chromatography on lipids in heart wood, and researched affinity among the species for the characteristics of color reaction. The results were summarized as follows; 1) Total-lipid in heart wood of the six species was 4.39%, mean free-lipid was 2.85% and mean bound-lipid was 1.54%. 2) All the six species; A. ginnala, A. mono, A. negundo, A. palmatum, A. saccharinum and A, triflorum were identified by the characteristics of color reaction. Judging from the color reactions, A. palmatum and A. triflorum seem to be closer than other species.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.43-48
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• 2005

To search of a new porcine pheromonal odorants for biostimulation control system technologies to offer a potentially useful and practical way to improve reproductive efficiency in livestock species, the holographic quantitative structure activity relationship (HQSAR) model between odorants, 2-phenoxytetrahydrofurane (A), 2-cyclohexyl-oxytetrahydrofurane (B), derivatives and binding affinity constants (p[Od.]/sub 50/) for porcine odorant-binding protein (pOBP) as receptor of pig pheromones were derivated and disscused. The binding affinity constants of cyclohexyl substituents (A) for pOBP were higher (A>B) than that of phenyl substituents (B). It was revealed that the optimum HQSAR model XI using PLS analyses had a fragment length (5∼8) with chirality at 5 components and hologram length 97 bin, which had a cross-validated q²(predictablities) of 0.916, and a conventional correlation coefficient r² (fitness) of 0.988, respectively. From the atomic contribution, the C3 and C5 atom in 2-oxyfuryl group contributed to binding affinity constants, whereas the central carbon atom in tert-butyl group on the cyclohexyl ring and the C4 atom of furyl group parts showed no contribution.