• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.106-108
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• 2005

The rutile polycrystal $Ti_{0.99}\;^{57}Fe_{0.01}O_2$ prepared with $^{57}Fe$ enriched iron have been studied by $M\ddot{o}ssbauer$ spectroscopy, X-ray diffraction and VSM. The $M\ddot{o}ssbauer$ spectrum of $Ti_{0.99}\;^{57}Fe_{0.01}O_2$ consists of a ferromagnetic and a paramagnetic phase over all temperature ranging from 4 to 300 K. Isomer shifts indicate $Fe^{2+}$ for the ferromagnetic phase, but $Fe^{3+}$ for the paramagneic phase of $Ti_{0.99}\;^{57}Fe_{0.01}O_2$ sample. It is noted that the magnetic hyperfine field of ferromagnetic phase had the value about 1.48 times as large as that of $\alpha$-Fe. The XRD data for $Ti_{0.99}\;^{57}Fe_{0.01}O_2$ showed a pure rutile phase with tetragonal structures without any segregation of Fe into particulates within the instrumental resolution limit The magnetic hysteresis (M-H) curve at room temperature showed an obvious ferromagnetic behavior and the magnetic moment per Fe atom under the applied field of 1 T was estimated to be about $0.71{\mu}_B$, suggesting a low spin configuration of Fe ions.

• Korean Journal of Materials Research
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• v.2 no.1
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• pp.76-82
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• 1992

Deposition of $TEOS-O_3$ oxide film as inter-metal dielectric layer shows the substrate dependency according to the substrate material and pattern density and pitch size. To minimize substrate and Pattern dependency, TEOS-base and $SiH_4-base$ Plasma oxide were predeposited as underlying material on the substrate. The substrate dependency of $TEOS-O_3$ oxide film was more significant on TEOS-base plasma oxide than on $SiH_4-base$ plasma oxide. The dependency of $TEOS-O_3$ oxide film was remarkably reduced, or nearly eliminated, by $N_2$plasma treatment on TEOS-base plasma oxide, which appears to be caused by the O-Si-N structure, observed on the the surface of TEOS-base plasma oxide.

• KSBB Journal
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• v.10 no.2
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• pp.183-190
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• 1995

The effects of enzymatic pretreatments on the bleaching of kraft pulp were studied. The kappa number of pulp samples which represents the lignin content of pulp decreased by 25.2% by the pretreatments with xylanase(EC 3.2.1.8, Pulpzyme HB) while it decreased by 13.7% without enzyme pretreatments after the extraction of the pretreated pulp samples in 1N NaOH. To enhance the effects of enzymatic pretreatment on the bleaching of kraft pulp, phenols were used as radical carriers with the simultaneous use of peroxidase(EC 1.11.1.7, Novozyme 502), $H_2O_2$, and xylanase. Guaiacol (1mM) was most effective by decreasing the kappa number by 29.6% when a low initial concentration of $H_2O_2$ (0.1mM) was used. The use of either a higher initial concentration of $H_2O_2$ or phenols lacking electron donating substituents such as phenol and p-chloyophenol, however, decreased the efficiency of enzymatic pretreatment indicating that the production rate and the stability of phenolic radicals are important parameters.

• Journal of the Korean Chemical Society
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• v.58 no.3
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• pp.258-266
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• 2014

Single crystals of cobalt(II) and nickel(II) complexes of 4-nitrobenzoic acid have been successfully grown by gel diffusion technique. The grown crystals were characterized by elemental analysis, FT-IR and UV-Visible spectroscopy. The structure of the grown crystals was elucidated using single crystal X-ray diffraction studies. The title compounds $[Co(Pnba)_2(H_2O)_4]{\cdot}2H_2O$ 1 and $[Ni(Pnba)_2(H_2O)_4]{\cdot}2H_2O$ 2 where PnbaH=4-nitrobenzoic acid, crystallize in centrosymmetric triclinic space group P-1. Magnetic susceptibility measurements reveal that the compounds are paramagnetic in nature. The mechanical strength of the grown crystals was determined by Vicker's microhardness studies. The ligand (4-nitrobenzoic acid) and the complexes have been screened for their biological activity against various bacteria and fungi. The activity data show that the biological activity of the complexes is higher than that of the ligand.

• Microbiology and Biotechnology Letters
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• v.24 no.3
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• pp.344-351
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• 1996

Microorganisms growing alcoholic distillery wastes were isolated from soil. Of them, the selected strain EL-9 had a capability of accumulating poly-$\beta$-hydroxybutyrate (PHB) when grown in alcoholic distillery wastes. The strain EL-9 was identified as a genus Actinobacillus based on the morphological, cultural, and biochemical characteristics. The strain EL-9 was named temporarily as Actino- bacillus sp. EL-9. The optimal temperature and pH for cell growth of Actinobacillus sp. EL-9 were 30$\circ$C and 7.0, respectively. The optimal medium compositions for cell growth comprised glucose 2%, NH$_{4}$NO$_{3}$ 0.15%, Na$_{2}$HP0$_{4}$-12H$_{2}$O 0.25%, KH$_{2}$PO$_{4}$ 0.25%, MgSO$_{4}$4-7H$_{2}$O 0.15%, FeSO$_{4}$-7H$_{2}$O 0.005%, CaCl$_{2}$-2H$_{2}$O 0.003% and trace element solution 5m/l. To investigate the optimal conditions for PHB production, two-stage culture technique was used. The result showed that the optimal conditions for PHB production are identical those for cell growth. When propionic acid was added as a cosubstrate, PHB/HV copolymer was produced.

• Journal of Energy Engineering
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• v.5 no.1
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• pp.65-71
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• 1996

Decomposition reaction of methanol was conducted on Ni-Cu/SiO$_2$catalysts with several variables. Variables used in this study are S.V(Space Velocity), partial pressure of methanol, reaction temperature, and composition rate of Ni-Cu. The range of S.V is 10,000-30,000h$\^$-1/, the temperature range is 150-400$^{\circ}C$ and values of Cu/(Ni＋Cu) are 0, 0.25, 0.5, 0.75, and 1. Over Ni/SiO$_2$, and Ni-Cu/SiO$_2$, the conversion rate of decomposition reaction of methanol arrived at 100% with increasing of temperature. At this time the selectivity of CO on Ni/SiO$_2$, was suddenly decreased, but on Ni-Cu/SiO$_2$, it was still sustained highly. The main products of reaction were CO and H$_2$, and by-products were CO$_2$ and CH$_4$mainly.

• Journal of Microbiology and Biotechnology
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• v.30 no.12
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• pp.1876-1884
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• 2020

Ethanol often accumulates during the process of wine fermentation, and mitophagy has critical role in ethanol output. However, the relationship between mitophagy and ethanol stress is still unclear. In this study, the expression of ATG11 and ATG32 genes exposed to ethanol stress was accessed by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). The result indicated that ethanol stress induced expression of the ATG11 and ATG32 genes. The colony sizes and the alcohol yield of atg11 and atg32 were also smaller and lower than those of wild type strain under ethanol whereas the mortality of mutants is higher. Furthermore, compared with wild type, the membrane integrity and the mitochondrial membrane potential of atg11 and atg32 exhibited greater damage following ethanol stress. In addition, a greater proportion of mutant cells were arrested at the G1/G0 cell cycle. There was more aggregation of peroxide hydrogen (H2O2) and superoxide anion (O2•-) in mutants. These changes in H2O2 and O2•- in yeasts were altered by reductants or inhibitors of scavenging enzyme by means of regulating the expression of ATG11 and ATG32 genes. Inhibitors of the mitochondrial electron transport chain (mtETC) also increased production of H2O2 and O2•- by enhancing expression of the ATG11 and ATG32 genes. Further results showed that activator or inhibitor of autophagy also activated or inhibited mitophagy by altering production of H2O2 and O2•. Therefore, ethanol stress induces mitophagy which improves yeast the tolerance to ethanol and the level of mitophagy during ethanol stress is regulated by ROS derived from mtETC.

• Korean Journal of Materials Research
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• v.11 no.1
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• pp.61-66
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• 2001

$TiO_2$films for photocatalytic reaction were synthesized by anodizing process. The photocatalytic efficiencies of anodized $TiO_2$were evaluated by the rate of decomposition of aniline blue. The properties of photocatalysis on anodic $TiO_2$films have been observed, but the efficiencies of photocatalytic reaction depended on the conditions of films formation. The microstructure of the anodic film formed in $H_2SO_4$ solution differed from that of $TiO_2$films formed in $H_2SO_4+H_3PO_4$ solution. It has been shown that the appropriate applied-voltage for anodizing of titanium for photocatalysis was 180V in both aqueous solutions.

• Resources Recycling
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• v.10 no.4
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• pp.24-33
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• 2001

For making a high degree of efficiency, this study attempts to gather each arisen-sludge from experiments and examine into its characteristics, in order to compare the biological reason of removing phosphorus with sintered body using calcite and the artificial reason of removing with a chemical reagent. First, it can be seen that sludge, which is identified CaCO$_3$, of 0.1∼0.2$\mu$m is regularly formed when using sintered body, calcite. And it is one of the results of the chemical methods in order to remove phosphorus that can be seen that sludges of 100∼50 $\mu$m are formed and that the forms of Ca$_2$P$_2$O$\_$7/, Ca$_3$(PO$_4$)$_2$$.$nH$_2$O, $\beta$-Ca$_2$P$_2$O$\_$7/ are shown when using a reagent, CaO dissolved water. The other of the results of the chemical methods can be seen that a lumpof sludge is formed when using wastewater and a reagent Ca$^2$$\^$+/ are used, and that the lump consists of Ca$_3$(PO$_4$)$_2$$.$nH$_2$O와 Ca$_2$H$_2$P$_4$O$\_$14/.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3835-3839
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• 2013

A new synthesis route for Pt nanoparticles by direct electrochemical reduction of a solid-state Pt ion precursor ($K_2PtCl_6$) is demonstrated. Solid $K_2PtCl_6$-supported polyethyleneimine (PEI) coatings on the surface of glassy carbon electrode were prepared by simple mixing of solid $K_2PtCl_6$ into a 1.0% PEI solution. The potential cycling or a constant potential in a PBS (pH 7.4) medium were applied to reduce the solid $K_2PtCl_6$ precursor. The reduction of Pt(IV) began at around -0.2 V and the reduction potential was ca. -0.4 V. A steady state current was achieved after 10 potential cycling scans, indicating that continuous formation of Pt nanoparticles by electrochemical reduction occurred for up to 10 cycles. After applying the reduction potential of -0.6 V for 300 s, Pt nanoparticles with diameters ranging from $0.02-0.5{\mu}m$ were observed, with an even distribution over the entire glassy carbon electrode surface. Characteristics of the Pt nanoparticles, including their performance in electrochemical reduction of $H_2O_2$ are examined. A distinct reduction peak observed at about -0.20 V was due to the electrocatalytic reduction of $H_2O_2$ by Pt nanoparticles. From the calibration plot, the linear range for $H_2O_2$ detection was 0.1-2.0 mM and the detection limit for $H_2O_2$ was found to be 0.05 mM.