• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1566-1573
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• 2014

Although most algae cultivation systems are operated in suspended culture, an attached growth system can offer several advantages over suspended systems. Algal cultivation becomes light-limited as the microalgal concentration increases in the suspended system; on the other hand, sunlight penetrates deeper and stronger in attached systems owing to the more transparent water. Such higher availability of sunlight makes it possible to operate a raceway pond deeper than usual, resulting in a higher areal productivity. The attached system achieved 2.8-times higher biomass productivity and total lipid productivity of $9.1g\;m^{-2}day^{-1}$ and $1.9g\;m^{-2}day^{-1}$, respectively, than the suspended system. Biomass productivity can be further increased by optimization of the culture conditions. Moreover, algal biomass harvesting and dewatering were made simpler and cheaper in attached systems, because mesh-type substrates with attached microalgae were easily removed from the culture and the remaining treated wastewater could be discharged directly. When the algal biomass was dewatered using natural sunlight, the palmitic acid (C16:0) content increased by 16% compared with the freeze-drying method. There was no great difference in other fatty acid composition. Therefore, the attached system for algal cultivation is a promising cultivation system for mass biodiesel production.

• Carbon letters
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• v.21
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• pp.16-22
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• 2017

Cobalt was electrodeposited onto chemical vapor deposition (CVD) graphene/Si/$SiO_2$ substrates, during different time intervals, using an electrolyte solution containing a low concentration of cobalt sulfate. The intention was to investigate the details of the deposition process (and the dissolution process) and the resulting magnetic properties of the Co deposits on graphene. During and after electrodeposition, in-situ magnetic measurements were performed using an (AGFM). These were followed by ex situ morphological analysis of the samples with ${\Delta}t_{DEP}$ 30 and 100 s by atomic force microscopy in the non-contact mode on pristine CVD graphene/$SiO_2$/Si. We demonstrate that it is possible to electrodeposit Co onto graphene, and that in-situ magnetic measurements can also help in understanding details of the deposition process itself. The results show that the Co deposits are ferromagnetic with decreasing coercivity ($H_C$) and demonstrate increasing magnetization on saturation ($M_{SAT}$) and electric signal proportional to remanence ($M_r$), as a function of the amount of the electrodeposited Co. It was also found that, after the end of the dissolution process, a certain amount of cobalt remains on the graphene in oxide form (this was confirmed by X-ray photoelectron spectroscopy), as suggested by the magnetic measurements. This oxide tends to exhibit a limited asymptotic amount when cycling through the deposition/dissolution process for increasing deposition times, possibly indicating that the oxidation process is similar to the graphene surface chemistry.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.251-254
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• 2003

Phosphorous removal rate and emergent plant growth were examined of a surface-flow constructed treatment wetland system, whose dimensions were 31 meter in length and 12 meter in width. The system was established on floodplain in the down reach of the Kwangju Stream in Korea in one and half months from May to June 2001. Cattails(Typha angustiflora) were transplanted in the system. They were dug out of natural wetlands and stems were cut at about 40 cm height from their bottom ends. Water of the Kwangju Stream were funneled into it via a pipe by gravity flow and its effluent were discharged back into it. The stems of cattails grew from 45.2 cm in July 2001 up to 186 cm in September 2001 and the number of cattail stems per square meter increased from 22 in July 2001 to 53 in September 2001. The early establishment of cattails was good. Volume and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow averaged $40\;m^3/day$ and hydraulic retention time was about 1.5 days. The concentration of total phosphorous in influent and effluent was 0.85 mg/L, 0.41 mg/L, respectively. The average removal rate of total phosphorous in the system was about 52%. The retention efficiency was slightly lower, compared with that in surface-flow wetlands operating in North America, whose retention efficiency was reported to be about 57%. The lower abatement rate could result from the initial stage of the system and inclusion of two cold months into the six-month monitoring period. Root rhizosphere in wetland soils and litter-soil layers on bottoms were not properly developed. Increase of standing density of cattails within a few years will establish both root zones and substrates beneficial to the removal of phosphorous, which may lead to increase of the phosphorous retention rate. The system was submerged one time by heavy storm during the monitoring period. The inundation, however, scarcely disturb its environment.

• Journal of Plant Biology
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• v.27 no.2
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• pp.61-72
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• 1984

The concept of natural grouping of plant designated as the "Amentiferous" is no longer given serious credence, and many of the families included in this grouping have been dispersed in diverse order. Because a review of taxonomic treatments of amentiferous taxa reveals diverse classifications, it has become necessary to investigate new characteristics and attempt to determine the significance of these characteristics in terms of amentiferous taxonomy. Protein analyses by isoelectrofocusing(IEF) and rocket immunoelectrophoresis(RIE) have proved to be useful in the delicitation of Quercus taxa using pollen extracts from selected taxa. When Quercus pollen extracts were separated by electrophoresis based on their isoelectric points in a stable pH gradient and substrates for estrase activity were stained, ten bands were revealed between pH 5-14. Within Lepidobalanus grouping, a great diversity in the pollen protein zymograms was observed with some segregation corresponding to the designated taxonomic sections. Two taxa of Cyclobalanopsis produced a zymogram that is somewhat similar to taxa included within the section Prinus of Lepidobalanus, and less similar to taxa within the section Cerris of the same subgenus. Three tested taxa of the Cerris are in the similar zymogram each other, being segregable from the taxa of Prinus. Quantitative and qualitative analyses for serological relationships within and among th Quercus were also employed. To calculate the degree of protein similarity, total rocket heights obtained from RIE provided an index of serological correspondence(SC). It is reconfirmed that the Quercus is distantly separated from the Fagus according to SC. Comparative data from rocket number and SC in the tested taxa of Quercus also indicate that Lepidobalanus is separable from Cyclobalanopsis. Within the Lepidobalanus Q. acutissima and Q. acutissima x variabilis are almost homogeneors and distinguishable from the other tested taxa of same subgenus. Although the number of taxa tested has been limited, the overall serological evidence best reflects the classification proposed by Redher(1940) and Melchior (1964), having the genus Quercus subdivided into three subgunera: Erythrobalanus, Lepidobalanus, and Cyclobalanopsis.alanopsis.

• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.112-115
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• 2012

To develop an efficient mass rearing system for Cadra cautella(Walker) and Orius laevigatus(Fieber) were investigated under the conditions of photoperiod 16L : 8D, $70{\pm}5%$ RH and $23{\pm}2^{\circ}C$. The highest efficiency rate(multiply 28.6) of C. cautella was achieved when using the rearing cage of $20{\ell}$ than $3{\ell}$. The highest efficiency rate(multiply 16.3) of O. laevigatus was achieved when using the rearing cage of $5{\ell}$ (adult 1,500, 10 pcs(10 cm) of plant of egg taking). The moth could be successfully reared with all food substrates tested, of which rice bran(43%) + chick feed(43%) + yeast(14%) assumed to be proper for mass-rearing in view of cost.

• Journal of Climate Change Research
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• v.8 no.4
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• pp.401-414
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• 2017

Vegetation and landscape characteristics at the three highest summits of Republic of Korea, i.e. Seoraksan, Jirisan and Hallasan, are analyzed on the basis of species composition, physiognomy, vegetation distribution and structure of alpine plants, along with landform, geology, soil and habitat conditions. Dominant high mountain plants at three alpine and subalpine belts contain deciduous broadleaved shrub, Rhododendron mucronulatum var. ciliatum (31.6%), and evergreen coniferous small tree, Pinus pumila (26.3%) at Seoraksan, deciduous broadleaved tree, Betula ermanii (35.3%), evergreen coniferous tree, Picea jezoensis (23.5%) at Jirisan, and evergreen coniferous tree, Abies koreana (22.6%), deciduous broadleaved shrub, Rhododendron mucronulatum var. ciliatum, and Juniperus chinensis var. sargentii (19.4%) at Hallasan, respectively. Presence of diverse landscapes at the peak of Seoraksan, such as shrubland, grassland, dry land along with rocky areas, and open land may be the result of hostile local climate and geology. High proportion of grassland and wetland at the top of Jirisan may related to gneiss-based gentle topography and well developed soil deposits, which are beneficial to keep the moisture content high. Occurrence of grassland, shrubland, dry land, conifer vegetation, and rocky area at the summit of Hallasan may due to higher elevation, unique local climate, as well as volcanic origin geology and soil substrates. Presences of diverse boreal plant species with various physiognomy at alpine and subalpine belts, and wide range of landscapes, including rocky, grassland, shrubland, wetland, and conifer woodland, provide decisive clues to understand the natural history of Korea, and can be employed as an relevant environmental indicator of biodiversity and ecosystem stability.

• Fisheries and Aquatic Sciences
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• v.25 no.4
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• pp.189-201
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• 2022

Jellyfish is an emerging aquaculture species, farmed for Oriental cuisines and nutraceutical ingredients. This study aimed to examine antioxidative and antimicrobial potentials of various fractions of the jellyfish, Acromitus hardenbergi. The bell and oral arms of the jellyfish were sequentially extracted with petroleum ether (PE), dichloromethane (DCM), chloroform (CHCl₃), methanol (MeOH), and water (H₂O) to extract its bioactive in an increasing polarity gradient. Test fractions were assayed for antiradical activities using electron spin resonance spectrometry, β-carotene-linoleate model and Folin-Ciocalteu assay; and antimicrobial activity against 2 Gram-negative bacteria, 4 Gram-positive bacteria and 2 fungal species using the disc diffusion assay. All fractions were also subjected to Fourier Transform Infrared (FTIR) analysis to identify types of functional groups present. It was found that the hydrophilic extracts (H₂O fractions) possessed the most effective radical scavenging activity (p < 0.05) while the lipophilic extracts (PE fractions) the most active antimicrobial activity, especially against Gram-positive bacteria (p < 0.05). Total oxidation substrates content was found to be highest in the PE fractions of jellyfish bell and oral arms (p < 0.05). FTIR data showed that the H₂O and MeOH fractions contains similar functional groups including -OH, -C=O, -N-H and -S=O groups, while the PE, DCM, and CHCl₃ fractions, the -CH₃, -COOH groups. This study showed that A. hardenbergi contains antioxidants and antimicrobials, thereby supporting the traditional claim of the jellyfish as an anti-aging and health-promoting functional food. Bioassay-guided fractionation approach serves as a critical milestone for the strategic screening, purification, and elucidation of therapeutically significant actives from jellyfish.

• Journal of Microbiology and Biotechnology
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• v.33 no.6
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• pp.788-796
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• 2023

Canine parvovirus type 2 (CPV-2) has high morbidity and mortality rates in canines. Nonstructural protein 1 (NS1) of CPV-2 has endonuclease activity, initiates viral DNA replication, and is highly conserved. Thus, it is a promising target for antiviral inhibitor development. We overexpressed a 41.9 kDa active recombinant endonuclease in Escherichia coli and designed a nicking assay using carboxyfluorescein and quencher-linked ssDNA as substrates. The optimal temperature and pH of the endonuclease were 37℃ and pH 7, respectively. Curcumin, bisdemethoxycurcumin, demethoxycurcumin, linoleic acid, tannic acid, and α-tocopherol inhibited CPV-2 NS1 endonuclease with IC₅₀ values of 0.29 to 8.03 µM. The extracted turmeric, yerba mate, and sesame cake suppressed CPV-2 NS1 endonuclease with IC₅₀ values of 1.48, 7.09, and 52.67 ㎍/ml, respectively. The binding affinity between curcumin, the strongest inhibitor, and CPV-2 NS1 endonuclease by molecular docking was -6.4 kcal/mol. Curcumin inhibited CPV-2 NS1 endonuclease via numerous hydrophobic interactions and two hydrogen bonds with Lys97 and Pro111 in the allosteric site. These results suggest that adding curcuminoids, linoleic acid, tannic acid, α-tocopherol, extracted turmeric, sesame cake, and yerba to the diet could prevent CPV-2 infection.

• Journal of Microbiology and Biotechnology
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• v.34 no.3
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• pp.725-734
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• 2024

CYP102A1 from Bacillus megaterium is an important enzyme in biotechnology, because engineered CYP102A1 enzymes can react with diverse substrates and produce human cytochrome P450-like metabolites. Therefore, CYP102A1 can be applied to drug metabolite production. Terpinen-4-ol is a cyclic monoterpene and the primary component of essential tea tree oil. Terpinen-4-ol was known for therapeutic effects, including antibacterial, antifungal, antiviral, and anti-inflammatory. Because terpenes are natural compounds, examining novel terpenes and investigating the therapeutic effects of terpenes represent responses to social demands for eco-friendly compounds. In this study, we investigated the catalytic activity of engineered CYP102A1 on terpinen-4-ol. Among CYP102A1 mutants tested here, the R47L/F81I/F87V/E143G/L188Q/N213S/E267V mutant showed the highest activity to terpinen-4-ol. Two major metabolites of terpinen-4-ol were generated by engineered CYP102A1. Characterization of major metabolites was confirmed by liquid chromatography-mass spectrometry (LC-MS), gas chromatography-MS, and nuclear magnetic resonance spectroscopy (NMR). Based on the LC-MS results, the difference in mass-to-charge ratio of an ion (m/z) between terpinen-4-ol and its major metabolites was 16. One major metabolite was defined as 1,4-dihydroxyp-menth-2-ene by NMR. Given these results, we speculate that another major metabolite is also a mono-hydroxylated product. Taken together, we suggest that CYP102A1 can be applied to make novel terpene derivatives.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.459-467
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• 2009

$Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were prepared on indium-tin-oxide(ITO)-coated glass substrates by using thermal evaporation. The crystallization was achieved by annealing the as-deposited films in flowing nitrogen. X-ray diffraction spectra showed that the $Cd_2GeSe_4$ and the $Cd_2GeSe_4:Co^{2+}$ films were preferentially grown along the (113) orientation. The crystal structure was rhomohedral(hexagonal) with lattice constants of $a=7.405\;{\AA}$ and $c=36.240\;{\AA}$ for $Cd_2GeSe_4$ and $a=7.43\;{\AA}$ and $c=36.81\;{\AA}$ for $Cd_2GeSe_4:Co^{2+}$ films. From the scanning electron microscope images, the $Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were plated, and the grain size increased with increasing annealing temperature. The optical energy band gap, measured at room temperature, of the as-deposited $Cd_2GeSe_4$ films was 1.70 eV and increased to about 1.74 eV and of the as-deposited $Cd_2GeSe_4:Co^{2+}$ films was 1.79 eV and decreased to about 1.74 eV upon annealing in flowing nitrogen at temperatures from $200^{\circ}C$ to $500^{\circ}C$. The dynamical behavior of the charge carriers in the $Cd_2GeSe_4$ and $Cd_2GeSe_4:Co^{2+}$ films were investigated by using the photoinduced discharge characteristics technique.