• Korean Journal of Crystallography
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• v.6 no.2
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• pp.125-133
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• 1995

The crystal structure of dehydrated, partially Co(II)-exchanged zeolite X, stoichiometry Co2+Na+-X (Co41+Na10Si100Al92O384) per unit cell, has been determined from three-dimensional X-ray diffraction data gathered by counter methods. The structure was solved and refined in the cubic space group Fd3:α=24.544(1)Å at 21(1)℃. The crystal was prepared by ion exchange in a flowing stream using a solution 0.025 M each in Co(NO3)2 and Co(O2CCH3)2. The crystal was then dehydrated at 380℃ and 2×10-6 Torr for two days. The structure was refined to the final error indices, R1=0.059 and R2=0.046 with 211 reflections for which I > 3σ(I). Co2+ ions and Na+ ions are located at the four different crystallographic sites. Co2+ ions are located at two different sites of high occupancies. Sixteen Co2+ ions are located at the center of the double six-ring (site I; Co-O = 2.21(1)Å, O-Co-O = 90.0(4)°) and twenty-five Co2+ ions are located at site II in the supercage. Twenty-five Co2+ ions are recessed 0.09Å into the supercage from its three oxygen plane (Co-O = 2.05(1)Å, O-Co-O = 119.8(7)°). Na+ ions are located at two different sites of occupandies. Seven Na+ ions are located at site II in the supercage (Na-O = 2.29(1)Å, O-Na-O = 102(1)°). Three Na+ ions are statistically distribyted over site III, a 48-fold equipoint in the supercages on twofold axes (Na-O = 2.59(10)Å, O-Na-O = 69.0(3)°). Seven Na+ ions are recessed 1.02Å into the supercage from the three oxygen plane. It appears that Co2+ ions prefer sites I and II in order, and that Na+ ions occupy the remaining sites, II and III.

• Food Science and Preservation
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• v.5 no.3
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• pp.247-255
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• 1998

This study was carried out to investigate changes in the flesh firmness, evolution of ethylene, cell wall components, and degradation and solubilization of polyuronide(PU) and polysaccharide(PS) in green(GP) and mature persimmon(MP) fruits according to testing time of ethylene(50${\mu}\ell$ㆍL$^{-1}$ ). When ethylene was treated in GP and MP, flesh firmness rapidly decreased and it was decreased more GP than MP. When ethylene were treated for 12 hours in GP, production of ethylene began after 3 days. The amount of ethylene product was maximum 16,000 ${\mu}\ell$ㆍL$^{-1}$ at 24 hours of ethylene treatment. However, ethylene was not producted until 7 days after 24 hours ethylene treatment at MP. The content of pectic substances decreased in the distilled- water, 0.05M $Na_2$CO$_3$,4M and 8M KOH-soluble fractions during softening according to increasing time of ethylene treatment. Arabinose and galactose were the major non-cellulosic neutral sugars in the 0.05M CDTA and 0.05M $Na_2$CO$_3$-soluble pectic fractions. Glucose, galactose and xylose were the major non-cellulosic neutral sugars in the 4M KOH- soluble hemicellulosic fraction. High molecular of PU and PS were degraded and solubilized in the distilled-water, 0.05M CDTA 0.05M $Na_2$CO$_3$ and 4M KOH-soluble fractions during time of ethylene treatment.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.1
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• pp.1-11
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• 2013

Additives such as glycerol, methanol, acetone, and ethanol were used to prevent $NaBO_2$ from precipitation, and their effects on hydrogen generation properties of $NaBH_4$ hydrolysis were investigated. When the concentration of additives was 5 wt%, the additives such as methanol, acetone, and ethanol could not prevent $NaBO_2$ precipitation. Although glycerol prevented $NaBO_2$ precipitation, conversion efficiency decreased to 78.0% due to its viscosity. Based on test results, hydrogen generation tests were also performed at various concentration of glycerol and methanol to investigate the concentration effects on hydrogen generation properties. As the concentration of glycerol increased from 1 wt% to 3 wt%, conversion efficiency increased owing to additive effect. When its concentration increased to 5 wt%, conversion efficiency decreased due to its viscosity. As the concentration of methanol increased from 5 wt% to 10 wt%, conversion efficiency increased owing to additive effect. When its concentration increased to 15 wt%, conversion efficiency decreased due to $NaB(OCH_3)_4$ precipitate. Although conversion efficiency decreased about 1% when 3 wt% glycerol was added, $NaBO_2$ precipitation was prevented. Consequently, addition of 3 wt% glycerol to $NaBH_4$ solution improves stability of hydrogen generation system.

• Korean Journal of Organic Agriculture
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• v.25 no.1
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• pp.135-148
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• 2017

Response Surface Methodology (RSM), which is combining with Plackett-Burman design and Box-Behnken experimental design, was applied to optimize the ratios of the nutrient components for carotenoid production by Rhodobacter sphaeroides PS-24 in liquid state fermentation. Nine nutrient ingredients containing yeast extract, sodium acetate, NaCl, $K_2HPO_4$, $MgSO_4$, mono-sodium glutamate, $Na_2CO_3$, $NH_4Cl$ and $CaCl_2$ were finally selected for optimizing the medium composition based on their statistical significance and positive effects on carotenoid yield. Box-Behnken design was employed for further optimization of the selected nutrient components in order to increase carotenoid production. Based on the Box-Behnken assay data, the secondary order coefficient model was set up to investigate the relationship between the carotenoid productivity and nutrient ingredients. The important factors having influence on optimal medium constituents for carotenoid production by Rhodobacter sphaeroides PS-24 were determined as follows: yeast extract 1.23 g, sodium acetate 1 g, $NH_4Cl$ 1.75 g, NaCl 2.5 g, $K_2HPO_4$ 2 g, $MgSO_4$ 1.0 g, mono-sodium glutamate 7.5 g, $Na_2CO_3$ 3.71 g, $NH_4Cl$ 3.5g, $CaCl_2$ 0.01 g, per liter. Maximum carotenoid yield of 18.11 mg/L was measured by confirmatory experiment in liquid culture using 500 L fermenter.

• Bulletin of the Korean Chemical Society
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• v.10 no.5
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• pp.426-430
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• 1989

Two crystal structures of iodine sorption complexes of dehydrated partially Co(Ⅱ )-exchanged zeolite A, $Co_{3.5}Na_5-A{\cdot}xI_2$, x = 2.5 and 5.0, have been determined by single crystal X-ray diffraction techniques. Both structures were solved and refined in cubic space group, Pm3m at $21(1)^{\circ}C$. The structures of $Co_{3.5}Na_5-A{\cdot}2.5I_2$(a = 12.173(1) ${\AA}$) and $Co_{3.5}Na_5-A{\cdot}5.0I_2$(a = 12.130(1) ${\AA}$) were refined to the final error indices, $R_1$ = 0.081 and $R_2$ = 0.077 with 261 reflections and $R_1$ = 0.103 and $R_2$ = 0.112 with 225 reflections, respectively, for which I>3${\sigma}$(I). In both structures, 3.5 $Co^{2+}$ ions and 4.5 $Na^+$ ions per unit cell lie at two crystallographically different 6-ring positions. 0.5 $Na^+$ ion lines in an 8-oxygen ring plane. Dehydrated $Co_{3.5}Na_5$-A sorbs 2.5 iodine molecules per unit cell at $70^{\circ}C$ (vapor pressure of $I_2$ is ca. 8.3 torr) within 30 minutes and 5 iodine molecules per unit cell at $80^{\circ}C$ (vapor pressure of $I_2$ is ca. 14.3 torr) within 24 hours. Each iodine molecule makes a close approach, along its axis to framework oxygen atom with I-I-O = $175^{\circ}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.1
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• pp.24-31
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• 2022

This study investigated microstructures, crystal structures, polarization, dielectric and electromechanical properties of 0.76Bi_1/2Na_1/2TiO₃-0.24SrTiO₃ (BNT-24ST)-based piezoceramcs by adding Li₂CO₃ and B₂O₃ (LB) as sintering aids for low-temperature sintering. All samples were successfully synthesized using conventional solid-state reaction method and sintered at 950, 1,000, 1,050, 1,100 and 1,175℃ for 2 hours. Without LB, specimens required sintering temperatures over 1,175℃ for sufficient densification, while the addition of 0.10-mol LB decreased the sintering temperatures down to 950℃. The average grain size and dielectric properties of BNT-24ST-10LB ceramics were enhanced with increasing sintering temperature. We found that the low-temperature sintered BNT-24ST piezoceramics by adding LB showed the d₃₃*value of 402 pm/V at 4 kV/mm after sintering at 1,050℃, which was better than that of high-temperature fired specimens sintered at 1,175℃ without LB (242 pm/V). We believe that the results of this study promise a candidate for low-cost multilayer ceramic actuator applications.

• Economic and Environmental Geology
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• v.43 no.3
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• pp.269-278
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• 2010

We investigated characteristics of the coloring material of Dancheong pigments and hope that this study contributes the revival of traditional Dancheong pigments color. For this purpose, we collected Dancheong fragment samples that fell off naturally from old wooden buildings in Gwangju and Jeonnam and analyzed the natural coloring material by XRD and EDS-SEM analysis method. In white pigments of Dancheong fragments, it is confirmed that gypsum$(CaSO_{4}{\cdot}2H_{2}O)$, quartz$(SiO_{2})$, white lead$(PbCO_{3})$ and calcite$(CaCO_{3})$ which have been used for white pigments since ancient times and $TiO_{2}$ which is common used in modern times. In red pigments of Dancheong fragments, it is confirmed that hematite$(Fe_{2}O_{3})$ and red lead$(Pb_{3}O_{4})$, which have been used for red pigments since ancient times and C.I. pigment orange $13(C_{32}H_{24}C_{12}N_{8}O_{2})$ but there is no cinnabar(HgS) which has been used since B.C. 3000 in China. In yellow pigments of Dancheong fragments, it is confirmed that crocoite$(PbCrO_{4})$ and massicot(PbO). In blue pigments of Dancheong fragments, it is confirmed that sodalite$(Na_{4}BeAlSi_{4}O_{12}Cl)$ and nosean $(Na_{8}Al_{6}Si_{6}O_{24}SO_{4})$ as coloring material of blue pigment and C.I. pigments blue $29(Na_{7}Al_{6}Si_{6}O_{24}S_{3})$ which is used in modern times. In green pigments of Dancheong fragments, it is confirmed that calumetite$(Cu(OHCI)_{2}{\cdot}2H_{2}O)$, escolaite(Cr2O3), dichromium trioxide$(Cr_{2}O_{3})$, emerald green$(C_{2}H_{3}As_{3}Cu_{2}O_{8})$, and C.I. pigments green$(C_{32}H_{16}-XCl_{x}Cu_{8})$ which is used in modern time. In black pigments of Dancheong fragments, Chiness ink(carbon black) is confirmed.

• Resources Recycling
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• v.24 no.4
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• pp.22-31
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• 2015

From results obtained by adjusting experimental variables based on the kinetic, the nucleation rate for formation of precipitated calcium carbonate (PCC) was investigated. Formation behavior of PCC was investigated for various concentrations of NaOH solution and $Na_2CO_3$ addition methods in the $Ca(OH)_2$ slurry. The range of nucleation rate was investigated for dissolution rates of major ion concentrations, $Ca^{2+}$ and $CO{_3}^{2-}$. In case of high concentration of major ions, vaterite and calcite were synthesized. The high nucleation rate was achieved for lower either $Ca^{2+}$ or $CO{_3}^{2-}$ ion concentration, calcite was mainly synthesized and when concentration of major ions was low, aragonite was synthesized. Furthermore, the formation of calcite was decreased with increasing concentration of NaOH. homogeneous aragonite could be obtained by addition 5 M NaOH. Therefore, in this study, specific shape of polymorphs could be prepared through controlling supersaturation.

• Textile Coloration and Finishing
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• v.13 no.2
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• pp.120-127
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• 2001

In order to make a microfiber fabric with PET/Co-PET Sea-Island Type microfiber, the optimum condition of extraction and elimination of Co-PET from the mocrofiber was examined. At the same time, the physical property change of the fabric with respect to the change of the relative amount of the Co-PET in the microfiber was also examined to provide a directly applicable data set to the industry. The sample fabric used was warp 75/36(DTY) and weft 0.05d(PET/Co-PET, Sea Island Type Microfiber) twill fabric of 36 separated yarns＋40/24(high shrinking yarn) with 130/48 ITY. The data set was made at various NaOH concentrations and steam temperatures with time as a main variable. The physical properties examined were the tensile properties. The results obtained were the tensile. The results obtained were 1. For a proper extraction of Co-PET (13.5%)from the microfiber with wet curing, it takes more than 5 min. in 8 and 12% of NaOH solutions but it takes only 3 min. in 18% of NaOH solution at 12$0^{\circ}C$. 2. For a proper extraction of Co-PET (13.5%) from the microfiber with wet curing, ti takes 3~5min. in 12 and 14% of NaOH solution and it takes less than 3 min. in 18% of NaOH solution at $130^\circ{C}$. 3. The increasing ratio of WT increased with increasing NaOH concentrations and the equilibrium point reached was 3 min. at $120^\circ{C}$. 4. The WT increasing ratio was greater in 14 and 18% NaOH solutions than in 8 and 12% of NaOH solutions at $130^\circ{C}$5. The RT ratio changes at $120^\circ{C}$ in 8 and 12% of NaOH solutions were indifferent from that at $130^\circ{C}$ in 12% of NaOH solution. However, the RT was apparently decreased with increasing NaOH concentration.

• Textile Coloration and Finishing
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• v.13 no.2
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• pp.34-34
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• 2001

In order to make a microfiber fabric with PET/Co-PET Sea-Island Type microfiber, the optimum condition of extraction and elimination of Co-PET from the microfiber was examined. At the same time, the physical property change of the fabric with respect to the change of the relative amount of the Co-PET in the microfiber was also examined to provide a directly applicable data set to the industry. The sample fabric used was warp 75/36(DTY) and weft 0.05d(PET/Co-PET, Sea Island Type Microfiber) twill fabric of 36 separated yarns＋40/24(high shrinking yarn) with 130/48 ITY. The data set was made at various NaOH concentrations and steam temperatures with time as a main variable. The physical properties examined were the tensile properties. The results obtained were the tensile properties. The results obtained were 1. For a proper extraction of Co-PET (13.5%)from the microfiber with wet curing, it takes more than 5 min. in 8 and 12% of NaOH solutions but it takes only 3 min. in 18% of NaOH solution at 120℃. 2. For a proper extraction of Co-PET (13.5%) from the microfiber with wet curing, it takes 3∼5 min. in 12 and 14% of NaOH solution and it takes less than 3 min. in 18% of NaOH solution at 130℃. 3. The increasing ratio of WT increased with increasing NaOH concentrations and the equilibrium point reached was 3 min. at 120℃. 4. The WT increasing ratio was greater in 14 and 18% NaOH solutions than in 8 and 12% of NaOH solutions at 130℃. 5. The RT ratio changes at 120℃ in 8 and 12% of NaOH solutions were indifferent from that at 130℃ in 12% of NaOH solution. However, the RT was apparently decreased with increasing NaOH concentration.