• Macromolecular Research
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• v.12 no.1
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• pp.100-106
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• 2004

We have prepared the polymethylene-bridged, dinuciear, half-sandwich constrained geometry catalysts (CGC)［Zr(η$\^$5/:η$^1$-C$\_$9/H$\_$5/SiMe$_2$NCMe$_3$)］$_2$［(CH$_2$)$\_$n/］［n=6(9), n=12(10)］by treating 2 equivalents of ZrCl$_4$with the corresponding tetralithium salts of the ligands in toluene. $^1$H and $\^$13/C NMR spectra of the synthesized complexes provide firm evidence for the anticipated dinuciear structure. In $^1$H NMR spectra, two singlets representing the methyl group protons bonded at the Si atom of the CGC are present at 0.88 and 0.64 ppm, which are considerably downfield positions relative to the shifts of 0.02 and 0.05 ppm of the corresponding ligands. To investigate the catalytic behavior of the prepared dinuciear catalysts, we conducted copolymerizations of ethylene and styrene in the presence of MMAO. The prime observation is that the two dinuclear CGCs 9 and 10 are not efficient for copo-lymerization, which definitely distinguishes them from the corresponding titanium-based dinuclear CGC. These species are active catalysts, however, for ethylene homopolymerization; the activity of catalyst 10, which contains a 12-methylene bridge, is larger than that of 9 (6-methylene bridge), which indicates that the presence of the longer bridge between the two active sites contributes more effectively to facilitate the polymerization activity of the dinuciear CGC. The activities increase as the polymerization temperature increases from 40 to 70$^{\circ}C$. On the other hand, the molecular weights of the polyethylenes are reduced when the polymerization temperature is increased. We observe that dinuciear metallocenes having different-length bridges give different polymerization results, which reconfirms the significant role that the nature of the bridging ligand has in controlling the polymerization properties of dinuclear catalysts.

• 한국해양학회지
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• v.24 no.1
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• pp.52-61
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• 1989

The daily net primary production by phytoplankton and ammonium excretion by macrozooplankton (> $350{\mu}m$) were measured to understand the nitrogenous nutrient dynamics in the southern part of the East Sea of Korea. At most of the staions, water columns were well stratified and strongly developed pycnoclines and matching nutriclines could be found near the 20-60m. Total chlorophyll ranged between $1.22-3.24{\mu}g$ ChI/l and nano-fractions of chlorophyll ranged from 43.2 to 99.6% in the surface layer. The daily net primary production by phytoplankton ranged from 0.75 to 2.04 gC/$m^2$/d and averaged to be 1.5 gC/$m^2$/d. 1t is evidenced that the primary production and chlorophyll content are relatively high in frontal waters where the North Korean Cold Water meets with the East Korean Warm Water. The turnover time of nitrate in the euphotic zone ranged from 0.2 day to 1.6 day and averaged to be 0.8 day. The N:P ratio of the study area shows on the average 13.4 which indicates nitrogenous nutrient to be the limiting factor for phytoplankton growth. Ammonium excretion by macrowoplankton averaged out to 1.3mg at-N/$m^2$/d, and contributed 7.3% of daily total nitrogen requirement by phytoplankton in this area. Calculation of upward flux of nitrate to the surface mixed layer from the lower layer approximates 7% of nitrogen requirement by phytoplankton.

• Korean Journal of Materials Research
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• v.16 no.4
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• pp.248-252
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• 2006

An investigation is reported on the coating of ZnS:Cu,Cl phosphors by $HfO_2$ using atomic layer deposition method. Hafnium oxide films were prepared at the chamber temperature of $280^{\circ}C$ using $Hf[N(CH_3)_2]_4\;and\;O_2$ as precursors and reactant gas, respectively. XPS and ICP-MS analysis showed the surface composition of coated phosphor powder was hafnium oxide. In FE-SEM analysis, the surface morphology of uncoated phosphors became smoother and clearer as the number of ALD cycle increased from 900 to 1800. The photoluminescence intensity for coated phosphors showed $7.3{\sim}13.4%$ higher than that of uncoated. The effect means that the reactive surface is uniformly coated with stable hafnium oxide to reduce the dead surface layer without change of bulk properties and also its absorptance is almost negligible due to ultrathin(nano-scaled) films. The growth rate is about $1.1{\AA}/cycle$.

• Journal of Mushroom
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• v.12 no.1
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• pp.35-40
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• 2014

Several bacteria are known as the causal agents of diseases of the cultivated button mushroom(Agaricus bisporus) and oyster mushroom(Pleurotus ostreatus). Pseudomonas tolaasii is the causal agent of brown blotch disease of commercial mushrooms. Pseudomonas sp. HC1 is a potent biological control agent to control brown blotch disease caused by Pseudomonas tolaasii. This can markedly reduce the level of extracellular toxins (i.e., tolaasins) produced by Pseudomonas tolaasii, the most destructive pathogen of cultivated mushrooms. To define the optimum conditions for the mass production of the Pseudomonas sp. HC1, we have investigated optimum culture conditions and effects of various nutrient source on the bacterial growth. The optimum initial pH and temperature were determined as pH 5.0 and $20^{\circ}C$, respectively. The optimal culture medium for the growth of tolaasin inhibitor bacterium was determined as follows: 0.9% dextrin, 1.5% yest extract, 0.5% $(NH_4)_2HPO_4$, 4mM $FeCl_3$, and 3.0% cysteine.

• Korean Journal of Crystallography
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• v.7 no.1
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• pp.8-19
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• 1996

Cholestryl Methyl and Propyl Carbonate(CH3OCOOC27H45, C3H7OCOOC27H45) are monoclinic, space group P21, with a=17.014(1), b=7.682(1), c=10.612(1)Å, β=103.05(1)°, Z=2, V=1351.16Å3, Dc=1.09 g/cm3 for methyl carbonate, and with a=13.683(1), b=11.864(2), c=18.904(2)Å, β=106.30(1)°, Z=4, V=2945.4Å3, Dc=1.06 g/cm3, Dm=1.06 g/cm3 for propyl carbonate. The intensity data were collected on an Enraf-Nonius CAD-4 diffractometer with a graphite monochromated Cu-Kα radiation. The structure was solved by direct methods and refined by full matrix least-squares methods. The final R factor was 0.051 for 2323 observed reflections for methyl carbonate and 0.074 for 3323 observed reflections for propyl carbonate. Compared with other cholesteryl derivatives, the cholesteryl ring and tail region of the molecules are normal. The molecules are stacked in clearly separated layers. At center of the layer, there are cholesteryl-C(17) side chain interactions. The interface region between layers is occupied by the loosely packed methyl carbonate chains. The structure of cholesteryl propyl carbonates have two propyl carbonates have two molecules(A, B) that are not related by crystal symmetry and have their tetracyclic system almost parallel to each other. Cholesteryl-cholesteryl interactions between symmetry related A-molecules, and cholesteryl-C(17) side chain interactions between symmetry related B-molecules occur at the center of the layers and these molecules stack along 2₁ screw axes. There are also C(17)chain-carbonate chain and C(17)chain-C(17)chain interactions in the interface region between layers. There is efficient packing between cholesteryl ring systems in propyl carbonates. Temperature ranges of cholesteric mesophases of cholesteryl alkyl cargonates are narrow for methyl, pentyl and hexyl carbonates, and rather broader for ethyl and propyl carbonates. Cholesteryl-isotropic transitions change very little with chain length.

• Investigative Magnetic Resonance Imaging
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• v.6 no.1
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• pp.35-40
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• 2002

Purpose : To evaluate the NMR relaxation properties and imaging characteristics of tissue-specificity for a newly developed macromolecular MR agent. Materials and methods : Phthalocyanine (PC) was chelated with paramagnetic ion, Mn.2.01g (5.2 mmol) of Phthalocyanine was mixed with 0.37g (1.4 mmol) of Mn chloride at $310^{\circ}C$ for 36 hours and then purified by chromatography (CHC13/CH3OH 98/2 v/v, Rf, 0.76) to obtain 1.04g (46%) of MnPC (molecular weight= 2000d). The $T1}T2$ relaxivity of MnPC was measured in 1.5T(64 MHz) MR using 0.1 mM MnPC. The MR image characteristics of MnPC was evaluated using spin-echo (TR/TE=500/14 msec) and gradient-echo (FLASH) (TR/TE=80/4 msec, flip angle=60) techniques in 1.57 MR scanner. The images of rabbit liver were obtained every 10 minutes up to 4 hours. To study the effect of concentration on image, 20 mM, 50 mM, 100 mM of MnPC were tested. Results : The relaxivities of MnPC at 1.5T(64MHz) were Rl=7.28 $mM^{-1}S^{-1},{\;}R2=55.56mM^{-1}S^{-1}$. Compared to the values of Gd-DTPA (Rl[=4.8 $mM^{-1}S^{-1})$], R2[=5.2 $mM^{-1}S^{-1}])$]), both T1/T2 relaxivities of MnPC were higher than those of Gd-DTPA. For both of SE and FLASH techniques, the contrast enhancement reached maximum at 10 minutes after bolus injection and the enhancement continued for more than 2 hours. When compared with small molecular weight liver agents such as Gd-EOB-DTPA, Gd-BOPTA and MnDPDP, MnPC was characterized by more prolonged enhancement time. The time course of MR images also revealed biliary excretion of MnPC. Conclusion : We developed a new macromolecular MR agent, MnPC. The relaxivities of MnPC were higher than those of small molecular weight Gd-chelate. Hepatic uptake and biliary excretion of MnPC suggests that this agent is a new liver-specific MR agent.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.3
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• pp.151-157
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• 2000

This study was carried out to isolate and identify the maysin and related flavonoid analogues in corn silks. Silks were covered with silk bag to prevent pollination and were sampled at 3-5 days after silking. The silks were filled with 100% MeOH and stored at $0^{\circ}C$ until analysis. The MeOH extracts of corn silks were filtered and concentrated at 35-4$0^{\circ}C$. The ${CH}_2$${Cl}_2$ was added on the concentrated aqueous solution to remove the chlorophyll and lipids. The Cis open column (25mm$\times$54 cm) was washed and activated with serial treatment of 500$m\ell$ of 100% MeOH(twice)longrightarrow75% MeOH longrightarrow50% MeOHlongrightarrow30% MeOHlongrightarrow100% $H_2$O(2 times). The concentrated aqueous solution was applied to the $C_{18}$ column and washed with $H_2O$ several times to remove the sugars and water soluble pigments. Neochlorogenic acid, chlorogenic acid and 4-caffeoylquinic acid were eluted with 10% MeOH, and rhamosyl isoorientin was eluted with 30% MeOH, but maysin was eluted with 50% MeOH from the $C_18$ open column. Collected fractions were analyzed with HPLC by using revers-phase Ultras-phere $C_{18}$ column (4.6$\times$250mm, 5$\mu\textrm{m}$) and $H_2$O (10% MeOH containing 0.1% $H_3$${PO}_4$)/MeOH (100% MeOH containing 0.1% H$_3$PO$_4$) linear gradient from 20% to 90% MeOH for 35 minutes, a flow rate of 1 $m\ell$/min and detection at 340nm. The selected fractions were concentrated and applied to the silicic acid column. Maysin was eluted with 500$m\ell$ of 100% ethyl acetate from the silicic acid column for the first purification, and the purity of collected fractions was about 75%, but the purity from the second purification with the Cis column (1/2 $\times$ 43") was greater than 95%. FAB-MS spectral data was obtained with VG7O-VSEQ VG analytical fast atom bombardment mass (UK). $^1$H-NMR and $^{13}$ C-NMR data were obtained with Bruker DPX 400 MHz NMR spectrometers (German) in DMSO-d$_{6}$ at 400 and 100 MHz, respectively.vely.

• Journal of the Korean Wood Science and Technology
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• v.49 no.3
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• pp.267-273
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• 2021

Camellia nut shell was collected, dried at room temperature and ground to get fine powder. The powder was extracted three times with 95% EtOH, combined, evaporated, and then freeze dried. The crude powder was dissolved in H₂O and then sequentially fractionated with n-hexane, CH₂Cl₂, EtOAc and n-BuOH. A part of EtOAc fraction was chromatographed on a silica gel and on a Sephadex LH-20 columns using MeOH, aqueous MeOH, EtOAc-n-hexane and EtOH-n-hexane to isolate gallotannins. Three gallotannins, 1,2-di-O-galloyl-β-D-glucopyranoside (2), 1,2,6-tri-O-galloyl-β-D-glucopyranoside (3) and 1,2,3,6-tetra-O-galloyl-β-D-glucopyranoside (4), including gallic acid (1), were isolated and elucidated by NMR and Mass spectroscopies. Although nothing new, these gallotannins were first reported from the nut shell extractives of camellia tree (Camellia oleifera C. Abel). This study was to investigate the chemical constituents, especially hydrolysable tannins, of nut shell extractives of Camellia oleifera and to provide basic information for the future chemical utilization of this species.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.153-160
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• 2007

Study for the effect of three different microbial feed additives(henceforth MA-A, MA-B, and MA-C) on feed coversion rate, and physical and chemical characteristics of swine finisher was conducted. MA-B had higher number of Lactobacillus spp. and yeast, compared to any other. The amylase activity of MA-B was also higher than any other. The daily feed intake rates of pigs fed control, MA-A, MA-B and MA-C were 3.15, 3.14, 3.31 and 3.42 kg, respectively. MA-C had the highest weight gain. However, there was no significant difference between treatments. The weights of feces daily excreted by pigs fed control, MA-A, MA-B, and MA-C were 2.14, 2.02, 2.18, and 2.23 kg/day, respectively. The volume of urine daily excreted by pigs fed control, MA-A, MA-B, and MA-C were 3.14, 3.26, 3.27, and $3.41\;{\ell}/day$, respectively. Water content, T-N, $P_{2}O_{5}$, and $K_{2}O$ in swine manure were not significantly different between treatments. The BOD were between 42,576 and $67,450\;mg/{\ell}$ for feces and were between 5,882.5 and $8,657.5\;mg/{\ell}$ for urine, respectively. The SS were between 138,000 and $180,000\;mg/{\ell}$ for feces and were between 875.0 and $1450.0mg/{\ell}$ for urine, respectively.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.282-287
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• 2001

This study was carried out to investigate the difference of ginsenoside compositions in crude ginseng saponins prepared by five different methods including three new methods. Two known methods are hot methanol(MeOH) extraction/n-butanol(n-BuOH) fractionation and hot MeOH extraction/Diaion HP-20 adsorption/MeOH elution. Three new methods are hot MeOH extraction/cation AG 50W $absorption/H_2O$ elution/n-BuOH extraction, cool MeOH extraction/Diaion HP-20 adsorption/MeOH elution and direct extraction with ethyl acetate(EtOAc)/n-BuOH. Analysis of ginsenoside composition in the crude saponins by conventional HPLC/RI(Refractive Index) did not show great difference between methods except EtOAc/n-BuOH method. However, HPLC/ELSD (evaporative light scattering detector) employing gradient mobile phase afforded fine resolution of ginsenoside Rf, $Rg_1$ and $Rh_1$, and great difference of ginsenoside compositions between methods. LC/MS revealed that large amount of prosapogenins were produced during the pass through the cation exchange (AG 50W) column being strongly acidic. Six major ginsenosides such as $Rb_1,w;Rb_2,$ Rc, Rd, Re and $Rg_1$, 5 prosapogenins and one chikusetsusaponin were identified by LC/MS. A newly established HPLC method employing ODS column and gradient mobile phase of $KH_2PO_4/CH_3CN$ revealed that malonyl ginsenosides were detected only in the crude saponin obtained from cool MeOH extraction.