• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.371-379
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• 2013

In order to improve the selective oxidation reaction of gaseous ammonia at a low temperature, various types of metal-impregnated activated alumina were prepared, and also physical and chemical properties of the conversion of ammonia were determined. Both types of metal (Cu, Ag) impregnated activated alumina show high conversion rate of ammonia at high temperature (over $300^{\circ}C$). However, at lower temperature ($200^{\circ}C$), Ag-impregnated catalyst shows the highest conversion rate (93%). In addition, the effects of lattice oxygen of the developed catalyst was studied. Ce-impregnated catalyst showed higher conversion rate than commercial alumina, but also showed lower conversion rate than Ag-impregnated sample. Moreover, 5 vol.% of Ag activation under hydrogen shows the highest conversion rate result. Finally, through high conversion at low temperature, it was considered that the production of NO and $NO_2$, toxic by-products, were effectively inhibited.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.10
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• pp.116-124
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• 2011

In this work, the effect of the initial concentration of methanol and ethanol, and the addition of oxygen molecules were discussed to improve the hydrogen generation using non-thermal plasma reactor effectively. In addition, the effect of ozone decomposition catalyst of manganese dioxide and its quantity was investigated. First, hydrogen concentration increased until an initial concentration of about 40,000[ppm] of methanol and thereafter it was saturated. Henceforth, hydrogen concentration decreased with increasing the oxygen percent on the carrier gas of nitrogen about both substances. Related with the effect of catalyst, it increased upto 60[g], but it was not changed largely after that. Consequently, it is confirmed that the hybrid process using plasma process and catalytic surface chemical reaction is a very promising way to increase the efficiency of hydrogen generation as investigated in this work.

• BMB Reports
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• v.34 no.5
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• pp.408-414
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• 2001

Ornithine decarboxylase (EC 4.1.1.17) is an essential enzyme for polyamine synthesis and growth in mammalian cells and plants. We compared the biochemical and immunological properties of rat and Nicotiana glutinosa ODC by cloning and expressing the recombinant proteins. The primary amino acid sequence between rat and N. glutinosa ODC had a 40% homology The molecular weight of the overexpressed rat ODC was 53 kDa, and that of N. glutinosa was 46.5 kDa. Adding 1 mM of putrescine to the enzyme reaction mixture inhibited both rat and N. glutinosa ODC activity to 30%. Agmatine had an inhibitory effect only on N. glutinosa ODC. Cysteine and lysine modifying reagents reduced both ODC activities, verifying the key roles of cysteine and lysine residues in the catalytic mechanism of ODC. ELISA was performed to characterize the immunological difference between the rat and plant ODC. Both the rat and N. glutinosa ODC were recognized by the polyclonal antibody that was raised against purified N. glutinosa ODC, but the rat ODC was 50-fold less sensitive to the antibody binding. These results indicate that even though both ODCs have the same evolutionary origin, there seems to be a structural distinction between the species.

• Journal of Powder Materials
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• v.24 no.2
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• pp.96-101
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• 2017

Well-dispersed platinum catalysts on ruthenium oxide nanofiber supports are fabricated using electrospinning, post-calcination, and reduction methods. To obtain the well-dispersed platinum catalysts, the surface of the nanofiber supports is modified using post-calcination. The structures, morphologies, crystal structures, chemical bonding energies, and electrochemical performance of the catalysts are investigated. The optimized catalysts show well-dispersed platinum nanoparticles (1-2 nm) on the nanofiber supports as well as a uniform network structure. In particular, the well-dispersed platinum catalysts on the ruthenium oxide nanofiber supports display excellent catalytic activity for oxygen reduction reactions with a half-wave potential ($E_{1/2}$) of 0.57 V and outstanding long-term stability after 2000 cycles, resulting in a lower $E_{1/2}$ potential degradation of 19 mV. The enhanced electrochemical performance for oxygen reduction reactions results from the well-dispersed platinum catalysts and unique nanofiber supports.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5304-5309
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• 2013

The degradation of methylethylkeone(MEK) was investigated by the continuous single module photocatalytic reactor. Operational conditions were initial concentration of MEK, intensity of photon flux, and activity change according to the long time operation. The photocatalytic degradation was decreased with the increase of MEK concentration, and the degree of decrease was larger at higher flow rate. Removal efficiency of photocatalytic reactor was decreased with the increase of reactor diameter and lamp wavelength under the same residence time condition. Continuous single module photocatalytic reactor was successfully operated without any activity drop during 120hrs operation.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.307-311
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• 2014

ZnS and $ZnS/TiO_2$ were prepared by chemical deposition. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM). The generation of reactive oxygen species was detected by monitoring the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Excellent catalytic degradation of methylene blue (MB) solution was observed using the $ZnS/TiO_2$ composites during irradiation with visible light. The results show that the photocatalytic performance of $TiO_2$ nanoparticles is improved by loading with ZnS.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.5
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• pp.412-418
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• 2010

Steam reforming of n-hexadecane, a major component of diesel over Ni-based hydrotalcite-like catalyst was carried out at $900^{\circ}C$ at atmospheric pressure with space velocity of $10,000h^{-1}$ and feed molar ratio of steam/carbon=3.0. Ni-based hydrotalcite catalyst was prepared by a solid phase crystallization (spc) method and characterized by $N_2$-physisorption, CO chemisorption, TPR., XRD, and TEM techniques. It was found that spc Ni/MgAl catalyst showed higher catalytic stability and inhibition of carbon formation than Ni/$\gamma-Al_2O_3$ catalyst under the tested conditions. The results suggest that the modified spc-Ni/MgAl catalyst after optimization may be applied for the SR reaction of diesel.

• Journal of the Korean Institute of Gas
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• v.7 no.1 s.18
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• pp.47-52
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• 2003

The adsorption characteristics of rert-butyl mercaptan(TBM) on base activated carbon and activated carbon impregnated with $CuCl_2$ or KI were studied. Adsorption of TBM on the surface of the KI or $CuCl_2$ impregnated activated carbon was detected by gas chromatograph equipped with a flame photometric detector. The amount of adsorption on those impregnated carbon found to be 7 or 8 times greater than on the non-impregnated activated carbon and varied according to the concentration of impregnated metal. FT-IR measurement showed that major reaction occuring on the surface of the catalytic adsorbent was dimerization of TBM into di-tert-butyl disulfide which had no stench.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.838-844
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• 2001

The enzyme Fuc aldolase from Methanococcus jannaschii that catalyzes the aldol condensation of DHAP and L-lactaldehyde to give fuculose-1-phosphate was inactivated by DEP. The inactivation was pseudo first-order in the enzyme and DEP, which was biphasic. A pseudo second-order rate constant of 120$M^{-1}min^{-1}$ was obtained at pH 6.0 and $25{\circ}C$. Quantifying the increase in absorbance at 240nm showed that four histidine residues per subunit were modified during the nearly complete inactivation. The statistical analysis and the time course of the modification suggested that two or three histidine residues were essential for activity. The rate of inactivation was dependent on the pH, and the pH inactivation data implied the involvement of the amino acid residue with a $pK_a$ value of 5.7. Fuc aldolase was protected against DEP inactivation by DHAP, indicating that the histidine residues were located at the active site of Fuc aldolase. DL-Glyceraldehyde, as an alternative substrate to L-lactaldehyde, showed no specific protection for the Fuc aldolase.

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1291-1298
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• 2015

Five different polymer nanofibers, namely, polyaniline nanofiber (PANI), magnetically separable polyaniline nanofiber (PAMP), magnetically separable DEAE cellulose fiber (DEAE), magnetically separable CM cellulose fiber (CM), and polystyrene nanofiber (PSNF), have been used for the immobilization of lactase (E.C. 3.2.1.23). Except for CM and PSNF, three polymers showed great properties. The catalytic activities (k_cat) of the free, PANI, PAMP, and magnetic DEAE-cellulose were determined to be 4.0, 2.05, 0.59, and 0.042 mM/min·mg protein, respectively. The lactase immobilized on DEAE, PANI, and PAMP showed improved stability and recyclability. PANI- and PAMP-lactase showed only a 0-3% decrease in activity after 3 months of vigorous shaking conditions (200 rpm) and at room temperature (25℃). PANI-, PAMP-, and DEAE-lactase showed a high percentage of conversion (100%, 47%, and 12%) after a 1 h lactose hydrolysis reaction. The residual activities of PANI-, PAMP-, and DEAE-lactase after 10 times of recycling were 98%, 96%, and 97%, respectively.