• Journal of Microbiology and Biotechnology
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• v.18 no.12
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• pp.1919-1926
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• 2008

Statistical experimental designs; involving (i) a fractional factorial design (FFD) and (ii) a central composite design (CCD) were applied to optimize the culture medium constituents for production of a unique antifreeze protein by the Antartic micro algae Chaetoceros neogracile. The results of the FFD suggested that NaCl, KCl, $MgCl_2$, and ${Na}_{2}{SiO}_{3}$ were significant variables that highly influenced the growth rate and biomass production. The optimum culture medium for the production of an antifreeze protein from C. neogracile was found to be Kalle's artificial seawater, pH of $7.0{\pm}0.5$, consisting of 28.566 g/l of NaCl, 3.887 g/l of $MgCl_2$, 1.787 g/l of $MgSO_4$, 1.308 g/l of $CaSO_4$, 0.832 g/l of ${K_2}{SO_4}$, 0.124 g/l of $CaCO_3$, 0.103 g/l of KBr, 0.0288 g/l of $SrSO_4$, and 0.0282 g/l of ${H_3}{BO_3}$. The antifreeze activity significantly increased after cells were treated with cold shock (at $-5^{\circ}C$) for 14 h. To the best of our knowledge, this is the first report demonstrating an antifreeze-like protein of C. neogracile.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.429-434
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• 2009

The OH($X^2{\Pi},\;{\nu}$"=0, 1) internal state distributions from the reaction of electronically ground state oxygen atoms with HSi$Cl_3$ were measured using laser-induced fluorescence. The ground-state O$(^3P_J)$ atoms with kinetic energies above the reaction barrier were produced by photolysis of N$O_2$ at 355 nm. The OH product revealed strong vibrational population inversion, P(${\nu}$"=1)/P(${\nu}$"=0) = 4.0 ${\pm}$ 0.6, and rotational distributions in both vibrational states exhibit substantial rotational excitations to the limit of total available energy. However, no preferential populations in either of the two $\Lambda$ doublet states were observed from the micropopulations, which supports a mechanism involving a direct abstraction of hydrogen by the atomic oxygen. It was also found that the collision energy between O and HSi$Cl_3$ is effectively coupled into the excitation of the internal degrees of freedom of the OH product ($$ = 0.62, and $<\;f_{rot}>$ = 0.20). The dynamics appear consistent with expectations for the kinematically constrained reaction which supports the reaction type, heavy + light-heavy $\rightarrow$ heavy-light + heavy (H + LH′ $\rightarrow$ HL + H′). The dynamics of oxygen atom collision with HSi$Cl_3$ are discussed in comparison to those with Si$H_4$.

• Journal of the Korean institute of surface engineering
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• v.25 no.4
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• pp.189-206
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• 1992

The effect of activation and electroless nickel plating conditions on contact properties was investi-gated for selective electroless nickel plating of Si wafers in order to obtain an optimum condition of con-tact hole filling. According to RCA prosess, p-type silicon (100) surface was cleaned out and activated. The effects of temperature, DMAB concentration, time, and strirring were investigated for activation of p-type Si(100) surface. The optimal activation condition was 0.2M HF, 1mM PdCl2, 2mM EDTA,$ 70^{\circ}C$, and 90sec under ultrasonic vibration. In electroless nickel plating, the effect of temperature, DMAB concentra-tion, pH, and plating time were studied. The optimal plating condition found was 0.10M NiSO4.H2O, 0.11M Citrate, pH 6.8, $60^{\circ}C$, 30minutes. The contact resistance of films was comparatively low. It took 30minutes to obtain 1$\mu\textrm{m}$ thick film with 8mM DMAB concentration. The film surface roughness was improved with decreasing temperature and decreasing pH of the plating solution. The best quality of the film was obtained at the condition of temperature $60^{\circ}C$ and pH 6.0. The micro-vickers hardness of film was about 800Hv. Plating rate of nickel on the hole pattern was slower than that of nickel on the line pattern.

• 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.

• Journal of the Korean Ceramic Society
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• v.28 no.6
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• pp.429-436
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• 1991

Silicon carbide has been grown by a chemical vapor deposition (CVD) technique using CH3SiCl3 and H2 gaseous mixture onto a graphite substrate. Based on the thermodynamic equilibrium studies and the suggestion that the deposition rate of SiC is controlled by surface reaction theoretical kinetic equation for CVD of silicon carbide has been proposed. The proposed theoretical kinetic equation for CVD of silicon carbide agreed well with the experimental results for the variation of the deposition rate as a function of the partial pressure of reactant gases. The Vikers microhardness of the SiC layer was about 3000∼3400 kg/$\textrm{mm}^2$ at room temperature.

• Journal of Integrative Natural Science
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• v.15 no.1
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• pp.19-25
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• 2022

The diarylsilyl compound, C₁₄H₁₂Br₄Si, was prepared from the reaction of 3,5-dibromophenyllithium with dimethyldichlorosilane, (CH₃)₂SiCl₂, at -78 ℃, can be a good synthon for derivatization to produce efficient host materials for organic light emitting diodes (OLEDs). Crystal structure analysis shows a slight deviation from ideal tetrahedral symmetry around the Si atom, whose conformation is effective in ensuring the maximum separation of the two phenyl rings and the two methyl substituents. The directions of the two aromatic rings are almost perpendicular to each other. The molecule exists as a monomer in the solid state.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.615-620
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• 2009

The present research was performed to determine the optimal firing condition and holding time for malayaite crystal, which is responsible for the stable pink-red coloration in glaze at high temperatures, using Cr$Cl_3$ as chromophore for the synthesis of $Cr_2O_3-SnO_2-CaO-SiO_2$ system pigments. The malayaite crystal was influenced by the raw materials used for synthesis, firing temperature, and holding time. Thus there are differences in the crystal phase and in the coloration according to the condition of synthesis. When Cr$Cl_3$ was used as chromophore, the pigment could be synthesized at lower temperatures, because Cr$Cl_3$ melts at $1500{^{\circ}C}$, which is much lower than the temperature at which $Cr_2O_3$ melts (higher than $2435{^{\circ}C}$). And the employed Cr ion showed a change in oxidation state. When a mineralizer was used to improve the employment of malayaite and the Cr ion, and the low temperature was maintained at which the malayaite crystal is produced, the production of malayaite crystal was promoted and the employment of chromophore was also promoted in the oxidation state of Cr (IV). The results of the experiment showed that the optimal firing condition was 18 h of holding time at $800{^{\circ}C}$, using Cr$Cl_3$ as chromophore, followed by 2 h at the raised temperature of $1150{^{\circ}C}$. The change in coloration of the Cr (IV) employed by malayaite showed a very rich color of red. Thus it was possible to effectively synthesize sphene-pink pigments with more red tint at a low temperature.

• Resources Recycling
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• v.22 no.2
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• pp.22-28
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• 2013

In the present study, the possibility of recovering and recycling the silicon carbide(SiC) from a silicon sludge by removing Fe and Si impurities was investigated. Si and SiC were separated from the silicon sludge using centrifugation. The separated SiC concentrate consisted of Fe, Si and SiC, in which Fe and Si were removed to recover the pure SiC. Leaching with acid/alkali solution was compared with the vapor-phase chlorination. The Fe concentration removed in the SiC was 49 ppm, and it was separated by leaching with 1 M HCl solution at $80^{\circ}C$ for 1 h. The Si concentration removed in the SiC was 860 ppm, and it was separated by leaching with 1M NaOH solution at $50^{\circ}C$ for 1 h. The SiC concentrate was chlorinated in a tubular reactor, 2.4 cm in diameter and 32 cm in length. The boat filled with SiC concentrate was located at the midpoint of the alumina tube, then, the chlorine and nitrogen gas mixture was introduced. The Fe and Si concentration removed in the SiC were 48 ppm and 405 ppm, respectively, at $500^{\circ}C$ reactor temperature, 4 h reaction time, 300 cc/min gas flow rate, and 10% $Cl_2$ gas mole fraction.

• Bulletin of the Korean Chemical Society
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• v.15 no.2
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• pp.126-132
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• 1994

RhCl [P($C_6H_5)_3]_3$ complexes have been incorporated in polysulfone (PS) as a dispersion medium using cosolvent (THF). The interactions between Rh(Ⅰ) complexes and polysulfone polymer molecules are examined by infrared spectroscopy and thermal analysis. The chemical reactivity of Rh in PS films has been investigated by reacting Rh sites with CO, $H_2,\;D_2,\;O_2\;NO,\;C_2H_2\;and\;C_2H_4$ in the temperature range $25-200^{\circ}C$. Various Rh-carbonyl, -hydride and -nitrosyl species formed in PS films are characterized by their infrared spectra. Rh complexes in PS film show interesting catalytic reactivities in the reactions such as hydrogenation of $C_2H_2\;and\;C_2H_4$, oxidation of CO, and reduction of NO by CO or $H_2$ gas under relatively mild conditions.

• The Journal of Engineering Geology
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• v.26 no.4
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• pp.561-570
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• 2016

For the investigation of hydrochemical changes in hot spring waters from the Onyang hot spring area, we analyzed water chemistry of 24 hot spring waters in 2011 and 2016. The results showed that there is no significant change in temperature and properties of the hot spring waters. The relationship of 2016 between temperature and $SiO_2$ and F reveals a positive trend ($r^2=0.60$, 0.47), and the relationship between temperature and Ca, Mg, Cl, $SO_4$, $HCO_3$, EC reveals a negative trend ($r^2=0.50$, 0.11, 0.50, 0.63, 0.23, 0.51). The relationship between temperature and pH is a positive trend, while the one between temperature and DO is a negative trend, indicating that the source is from deep groundwater. When plotted on Piper diagram, most of which are $Na-HCO_3$ but several hot waters are classified as the $Na(Ca)-HCO_3$, indicating inflow of shallow groundwater was occurred.