• Korean Journal of Microbiology
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• v.47 no.4
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• pp.289-294
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• 2011

We investigated the cold shock sensitivity of DEAD-box RNA helicase gene deleted strains of in Bacillus subtilis CU1065. To understand cold shock effects, cells were cultivated at $37^{\circ}C$ to log phase ($O.D_{600}$=0.5-0.6) and then temperature was shifted to $15^{\circ}C$. Cold shock slow down the growth rate of wild type and deleted strains of DEAD-box RNA helicase gene (ydbR, yfmL, yqfR, deaD). The growth rate of ydbR deleted strain is 5 times severely reduced compared to that of wild type strain (CU1065). But the growth rate of other three (yfmL, yqfR, deaD) deleted strains is nearly equal to the growth rate of wild type. Compared to $37^{\circ}C$, the amount of ydbR and yqfR mRNA transcripts are increased at the growth temperature of $15^{\circ}C$. On the other hands the mRNA transcripts of yfmL and deaD are not changed at both conditions of $37^{\circ}C$ and $15^{\circ}C$. Upon cold shock treatment ydbR mRNA transcript is clearly increased. After treatment of rifampicin (bacteria transcription inhibitor) the amount of ydbR mRNA was measured. Temperature shift from $37^{\circ}C$ to $15^{\circ}C$ and rifampicin treatment showed slowly decay of ydbR mRNA. But at $37^{\circ}C$ and rifampicin treatment ydbR mRNA is rapidly reduced. These results showed that cold shock induction of ydbR mRNA resulted from the stability of ydbR mRNA and not from the transcription induction of ydbR. In relation to these results, we found the cold box element of csp (cold shock protein gene) in 5' untranslated region of ydbR gene. Cold shock induction of ydbR is caused by the stability of ydbR mRNA like the stability of csp mRNA.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.2
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• pp.69-80
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• 2023

This study investigated the differences in barley growth at different growth stages (Dec, Feb, and Apr) and the yield at harvest in three groups (G1, G2, and G3) with different climates. Additionally, we measured meteorological differences between areas during the growing season to determine which factors were related to growth and yield differences. We evaluated the chemical composition of soil and the mineral content in leaves during the heading stages. We also recorded the main constituents, amino acids, and mineral compositions of barley seeds grown in different areas. Tiller number/m² in G1 areas was higher than in G2 and G3 when measured before and after overwintering. However, tiller number/m² and dry aboveground plant parts/m² in G2 and G3 areas were higher than in G1. Regrowth, panicle formation, and heading days in G2 areas occurred slightly later than in G1 and G3. However, there was no difference in chlorophyll content (SPAD value) between groups. The yield in G1 areas was 9~15% less than in G1 and G3. The decrease in yield in G2 areas could be due to lower panicle number, spikelet number, and ripening rate. In addition, the decrease in yield in G2 areas is likely because maximum, minimum, and average daily temperatures during the growing season were lower than those in G1 and G3. However, mineral nutrients in the soil were higher in the G2 area than in G1 and G3. The overall mineral content in plants tended to be higher in G1 areas than in G2 and G3. Mineral content such as Cu, K, Mg, and P in G3 areas and crude protein and most amino acids in G2 areas tended to be relatively low compared to other areas. Thus, the G1 area may be suitable for barley cultivation without adverse impacts on barley yield, main constituents, amino acids, and mineral contents compared to the main producing areas in G3.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.4
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• pp.259-264
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• 2001

Typhoon and neap tide on Cochlodinium polykrikoides bloom and water temperature on disappearance of C. polykrikoides bloom were investigated to elucidate the outbreak mechanism of C. polykrikoides blooms at Naro and Namhae coastal area in South Sea of Korea. The first observation of C. polykrikoides blooms were observed when thermocline was disappeared by typhoon, tide, etc. The first blooms of C. polykrikoides were observed on neap tide or before one day from neap tide in 1996-1998 and 2000. However, thermocline was disappeared by typhoon in 1994 and 1999, the first blooms were observed early 12-30 day than 1996-1998 and 2000. The main reason of disappearance of C. polykrikoides blooms after typhoon on 1997-2000 seems to be other environmental change by typhoon rather than low water temperature. In the future, the first C. polykrikoides bloom will be appear around the first neap tide of latter part of August with breaking down of thermocline, but if the thermocline be collapsed by typhoon in July, the C. polykrikoides bloom will be appear at beginning of August. The outbreak of C. polykrikoides blooms will be explain as follows: The vegetative cells, which was germinated by environmental change or already exist in surface water at low level, input to the surface water, and then nutrients and trace metals which were suppled from out side of C. polykrikoides bloom area inflow to surface. The vegetative cells are growth by the nutrients and trace metals at suitable environmental conditions e.g. water temperature, salinity, and sufficient light.

• Korean Journal of Medicinal Crop Science
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• v.13 no.6
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• pp.255-260
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• 2005

For selecting a new candidate as functional material, this study was conducted on in vitro antioxidant activity and total phenol content of methanol and water extracts prepared from two Mentha species (M viridis L. (M spicata L.) and Mentha piperita L, Extracts of M. viridis showed more efficient scavenging activity on superoxide and DPPH ${({\alpha},{\alpha}-diphenyl-{\beta}-picrylhydrazyl)}$ radical and inhibitory activity on oxidation of human low density lipoprotein (LDL) induced by $CuSO_4$ and auto-oxidation of linoleic acid than those of M piprita. Methanol extract $(65.88%{\sim}77.59%)$ and water extract $(37.69%{\sim}87.21%)$ of M. viridis also exhibited more potent inhibitory activity on LDL oxidation than that of ${{\alpha}-tocopherol\;(28.37%{\sim}66.54%)}$ at ${1{\sim}100\;{\mu}g/ml}$ of final concentration. The total phenol contents of methanol extract and water extract of Mviridis (17.95% & 10.18%, respectively) as tannic acid equivalent were higher than those of M piperita (15.44% & 9.19%). But the yields of methanol and water extracts of M. viridis (13.3 % & 13.5%) were lower than those of M. piperita (14.1 % & 14.6%). The results implies that the extracts from M. viridis (spicata) is more useful material for industrialization as functional food than those from M. piperita.

• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.201-207
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• 1993

Starting ingot of $Pr_{15}Fe_{77}B_{8}$ were prepared by vacuum induction melting under argon atmosphere. The ingot were induction melted in a quartz crucible and then ejected as a molten alloy throuth a 0.6 mrn orifice onto a rotating cop¬per wheel. An anisotropic magnet was prepared from ribbon by hot deformation techniques. A fully dense precursor magnet first made by pressing ribbons at $680^{\circ}C$ under a pressure of $21.8\;kg/mm^{2}$. A substantially oriented magnets were obtained by die-upset under various conditions. As the compression ratio increases, the $B_{r}$ value increases pronouncedly though $_{i}H_{c}$ decreases. Also, XRD analyses show increased diffraction peak from (006). From these results, it can be known that the magnetic easy axis was formed along the compression axis. As the die-upset speed increases, $_{i}H_{c}$ increases though $B_{r}$ decreases. The $B_{r}$ increases up to $750^{\circ}C$ of die-upset temperature and above this temperature decreases. The value of $4{\pi}M_{s}$ of the $Pr_{15}Fe_{77}B_{8}$ alloy prepared is found to be 11.8 KG. When the alloy was compressed by 0.8 under the die-upset speed of 0.05 m/sec at $750^{\circ}C$, $B_{r}$ was 11.0 KG indicating that the alloy has excellent magnetic anistropy. However, this alloy has some limitation because of low $_{i}H_{c}$.

• Culinary science and hospitality research
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• v.15 no.3
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• pp.284-293
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• 2009

This study investigated chemical composition and antioxidant activity in the aerial parts or roots of Korean and Chinese Cirsium. Water was abundant in their roots than their aerial parts, and its content was similar between Korean Cirsium and Chinese one. Ash was abundant in the aerial parts of Korean one. Protein was abundant in the aerial parts of Korean one and the roots of Chinese one. Lipid content was abundant in the roots of Chinese one. Carbohydrate was abundant in the roots of Korean one while K content was abundant in the roots of Chinese one. Ca and Mg contents were abundant in the aerial parts of Korean one. P and Fe contents were abundant in the aerial parts of Korean one. Cu content was abundant in the aerial parts of Korean and Chinese ones. Vitamin A and vitamin C were not detected, but vitamin E and $\beta$-carotene were contained 5.35 IU/100 g, 1113.18 ${\mu}g$/100 g in the aerial parts of Korean one. Yield, total phenolics and total flavonoid contents were abundant in the roots of Korean one. Silymarin, cynarin, and narirutin were not detected in Korean and Chinese ones, but apigenin was identified in the aerial parts of Korean one. Acacetin was identified in the roots of Chinese one. Antioxidant activity was low in Korean and Chinese ones. These results suggest that nutrition composition, total phenolic content, total flavonoid content and apigenin content in the aerial parts of Korean Cirsium was superior than those in the roots of Korean and Chinese Cirsium.

• Journal of Soil and Groundwater Environment
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• v.14 no.4
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• pp.45-53
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• 2009

This study concerned remediation of heavy metal contaminated farmland soils near abandoned mine, using stabilization method, with particular emphasis on the remediating the soils contaminated with multi-elements. In this study, stabilizing heavy metals based on 'In-situ chemical fixation' has been applied to the soil collected from an abandoned mine in Korea, using column test, with various stabilizing agents, including $FeSO_4$, $KMnO_4$, sludge (collected from coal mine drainage treatment pond), zero-valent iron (ZVI), zeolite and $CaCO_3$. Sixty five-days operation of the flow-through columns yield $FeSO_4\;+\;KMnO_4$ and zeolite are efficient on reducing As leaching from the soil. ZVI and sludge are reducing the leaching of Cu. Although $FeSO_4\;+\;KMnO_4$ seem to be efficient for most heavy metals, high pH in the initial stage of test enabled high leaching of the heavy metals, whereas fixation of the heavy metals maintain throughout the rest of the test period, with increasing pH up to around 6. Addition of some alkaline agent may inhibit the low pH during the application. The column test was also run as two set: one set incubated with deionized water for 72 hours prior to starting the test, and the other without incubation. The incubated set demonstrated better stabilizing efficiency, indicating the potential optimized operation method.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.174-174
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• 2000

A strong antiferromagnetic coupling in Fe/Si multilayered films (MLF) had been recently discovered and much consideration has been given to whether the coupling in the Fe/Si MLF system has the same origin as the metal/metal MLF. Nevertheless, the nature of the interfacial ron silicide is still controversial. On one hand, a metal/ semiconductor structure was suggested with a narrow band-gap semiconducting $\varepsilon$-FeSi spacer that mediates the coupling. However, some features show that the nature of coupling can be well understood in terms of the conventional metal/metal multilayered system. It is well known that both magneto-optical (MO) and optical properties of a metal depend strongly on their electronic structure that is also correlated with the atomic and chemical ordering. In this study, the nature of the interfacial regions is the Fe/Si multilayers has been investigated by the experimental and computer-simulated MO and optical spectroscopies. The Fe/Si MLF were prepared by rf-sputtering onto glass substrates at room temperature with the number of repetition N=50. The thickness of Fe sublayer was fixed at 3.0nm while the Si sublayer thickness was varied from 1.0 to 2.0 nm. The topmost layer of all the Fe/Si MLF is Fe. In order to carry out the computer simulations, the information on the MO and optical parameters of the materials that may constitute a real multilayered structure should be known in advance. For this purpose, we also prepared Fe, Si, FeSi2 and FeSi samples. The structural characterization of Fe/Si MLF was performed by low- and high -angle x-ray diffraction with a Cu-K$\alpha$ radiation and by transmission electron microscopy. A bulk $\varepsilon$-FeSi was also investigated. The MO and optical properties were measured at room temperature in the 1.0-4.7 eV energy range. The theoretical simulations of MO and optical properties for the Fe/Si MLF were performed by solving exactly a multireflection problem using the scattering matrix approach assuming various stoichiometries of a nonmagnetic spacer separating the antiferromagnetically coupled Fe layers. The simulated spectra of a model structure of FeSi2 or $\varepsilon$-FeSi as the spacer turned out to fail in explaining the experimental spectra of the Fe/Si MLF in both intensity and shape. Thus, the decisive disagreement between experimental and simulated MO and optical properties ruled out the hypothesis of FeSi2 and $\varepsilon$-FeSi as the nonmagnetic spacer. By supposing the spontaneous formation of a metallic ζ-FeSi, a reasonable agreement between experimental and simulated MO and optical spectra was obtained.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.292-292
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• 2016

Transition metal dichalcogenides (TMDs) with a two-dimensional layered structure have been considered highly promising materials for next-generation flexible, wearable, stretchable and transparent devices due to their unique physical, electrical and optical properties. Recent studies on TMD devices have focused on developing a suitable doping technique because precise control of the threshold voltage ($V_{TH}$) and the number of tightly-bound trions are required to achieve high performance electronic and optoelectronic devices, respectively. In particular, it is critical to develop an ultra-low level doping technique for the proper design and optimization of TMD-based devices because high level doping (about $10^{12}cm^{-2}$) causes TMD to act as a near-metallic layer. However, it is difficult to apply an ion implantation technique to TMD materials due to crystal damage that occurs during the implantation process. Although safe doping techniques have recently been developed, most of the previous TMD doping techniques presented very high doping levels of ${\sim}10^{12}cm^{-2}$. Recently, low-level n- and p-doping of TMD materials was achieved using cesium carbonate ($Cs_2CO_3$), octadecyltrichlorosilane (OTS), and M-DNA, but further studies are needed to reduce the doping level down to an intrinsic level. Here, we propose a novel DNA-based doping method on $MoS_2$ and $WSe_2$ films, which enables ultra-low n- and p-doping control and allows for proper adjustments in device performance. This is achieved by selecting and/or combining different types of divalent metal and trivalent lanthanide (Ln) ions on DNA nanostructures. The available n-doping range (${\Delta}n$) on the $MoS_2$ by Ln-DNA (DNA functionalized by trivalent Ln ions) is between $6{\times}10^9cm^{-2}$ and $2.6{\times}10^{10}cm^{-2}$, which is even lower than that provided by pristine DNA (${\sim}6.4{\times}10^{10}cm^{-2}$). The p-doping change (${\Delta}p$) on $WSe_2$ by Ln-DNA is adjusted between $-1.0{\times}10^{10}cm^{-2}$ and $-2.4{\times}10^{10}cm^{-2}$. In the case of Co-DNA (DNA functionalized by both divalent metal and trivalent Ln ions) doping where $Eu^{3+}$ or $Gd^{3+}$ ions were incorporated, a light p-doping phenomenon is observed on $MoS_2$ and $WSe_2$ (respectively, negative ${\Delta}n$ below $-9{\times}10^9cm^{-2}$ and positive ${\Delta}p$ above $1.4{\times}10^{10}cm^{-2}$) because the added $Cu^{2+}$ ions probably reduce the strength of negative charges in Ln-DNA. However, a light n-doping phenomenon (positive ${\Delta}n$ above $10^{10}cm^{-2}$ and negative ${\Delta}p$ below $-1.1{\times}10^{10}cm^{-2}$) occurs in the TMD devices doped by Co-DNA with $Tb^{3+}$ or $Er^{3+}$ ions. A significant (factor of ~5) increase in field-effect mobility is also observed on the $MoS_2$ and $WSe_2$ devices, which are, respectively, doped by $Tb^{3+}$-based Co-DNA (n-doping) and $Gd^{3+}$-based Co-DNA (p-doping), due to the reduction of effective electron and hole barrier heights after the doping. In terms of optoelectronic device performance (photoresponsivity and detectivity), the $Tb^{3+}$ or $Er^{3+}$-Co-DNA (n-doping) and the $Eu^{3+}$ or $Gd^{3+}$-Co-DNA (p-doping) improve the $MoS_2$ and $WSe_2$ photodetectors, respectively.

• Korean Journal of Environmental Agriculture
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• v.23 no.3
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• pp.170-177
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• 2004

Agroenvironmental characteristics in paddy fields irrigated with the water of Nagdong river were analyzed along the river watershed for two years from 1999. The sites monitored from upper reaches of the river were Andong, Sangju, Gumi, Goryeong, Changnyeong, Milyang and Pusan. In paddy soils, the contents of heavy metals such as Cd, Cr, Cu, Pb, Ni, Zn and As were around natural values showing the highest values in Pusan followed by Goryeong. In brown rice, the contents of heavy metals were lower than natural values. Soil chemical properties appeared higher values in the lower reaches including Goryeong than the upper ones. The highest parameters in Goryeong were pH ($5.9{\sim}6.1$), EC ($0.8{\sim}0.9\;dS/m$), $Av.P_2O_5$ ($155{\sim}201\;mg/kg$), exchangeable Ca ($6.7{\sim}7.4\;cmol^+/kg$), Mg ($1.92{\sim}2.50\;cmol^+/kg$), K ($0.18{\sim}0.21\;cmol^+/kg$) and those in Pusan were organic matter ($23.0{\sim}29.1\;g/kg$) and T-N ($1.6{\sim}1.8\;mg/kg$). In conclusion, the recommended rates of N fertilizer for rice cropping were 21.4%, 11.8% and 8.8% high for Andong, Sangju and Gumi, respectively and 14.9%, 4.6%, 4.5% and 11.5% low for Goryeong, Changnyeong, Milyang and Pusan, respectively reflecting the chemical properties of soils and the quality of irrigation water on the basis of 110 kgN/ha. In the case of phosphorous, the rates were 18.9% and 33.3% low for Changnyeong and others, respectively on the basis of $45\;kgP_2O_5/ha$. The populations of bacteria, fungi, actinomycetes, Bacillus, fluorescent Pseudomonas and Biomass C were high at the lower reaches including Goryeong, which showed relatively much nutrient contents of organic matter, total N and phosphorous etc.