• Journal of the Korean Applied Science and Technology
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• v.28 no.3
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• pp.321-328
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• 2011

The autothermal reforming reaction of methane was investigated to produce hyd rogen with Ni/$CeO_2-ZrO_2$, Ni/$Al_2O_3$-MgO and Ni-Ru/$Al_2O_3$-MgO catalysts. Honeycomb metalli c monolith was applied in order to obtain high catalytic activity and stability in autothermal r eforming. The catalysts were characterized by XRD, BET and SEM. The influence of various catalysts on hydrogen production was studied for the feed ratio($O_2/CH_4$, $H_2O/CH_4$). The $O_2/CH_4$ and $H_2O/CH_4$ ratio governed the methane conversion and temperature profile of reactor. Th e reactor temperature increased as the reaction shifted from endothermic to exothermic reactio n with increasing $O_2/CH_4$ ratio. Among the catalysts used in the experiment, the Ni-Ru/$Al_2O_3$-MgO catalyst showed the highest activity. The 60% of $CH_4$ conversion was obtained, and th e reactor temperature was maintained $600^{\circ}C$ at the condition of GHSV=$10000h^{-1}$ and feed ratio S/C/O=0.5/1/0.5.

• Archives of Pharmacal Research
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• v.22 no.2
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• pp.219-224
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• 1999

In our search for the anticonvulsant consitutent of Gastrodia elata repeated column chromatographies guided by activity assay led to isolation of an active compound, which was identified as gastrodin on the basis of spectral data. Brain succinic semialdehyde dehydrogenase (SSADH) was inactivated by preincubation with gastrodin in a time-dependent manner and the reaction was monitored by absorption and fluorescene spectroscopic methods. The inactivation followed pseudo-first-order kinetics with the second-rate order constant of $1.2{\times}10^{3} M^{-1} min^{-1}$. The time course of the reaction was significantly affected by the coenzyme NAD^{+}$, which affected complete protection against the loss of the catalytic activity, whereas substrate succinic semialdehyde failed to prevent the inactivation of the enzyme. It is postulated that the gastrodin is able to elevate the neurotransmitter GABA levels in central nervous system by inhibitory action on one of the GABA degradative enzymes, SSADH.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.400-404
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• 2011

The activity and stability of the metal filter material Pt coated on NOx and soot oxidation were examined. The catalytic reaction test for NOx and soot were also performed independently and simultaneously. As a result, it showed the NO to $NO_2$ shift reaction with 20% conversion, NOx decomposition (about 10%) and perfect soot oxidation on the material Pt coated proceeded. Onset temperature of soot oxidation shift to lower temperature (about $30^{\circ}C$) by generated $NO_2$. The material also was less affected by thermal shock than $Pt/Al_2O_3$ or $Pt/TiO_3$ catalysts due to its stability of surface structure.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.592-597
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• 2001

The pyruvate dehydrogenase complex (PDC) catalyzes the oxidative decarboxylation of pyruvate with the formation of $CO_2$, acetyl-CoA, NADH, and H+. This complex contains multiple copies of three catalytic components including pyruvate dehydrogenase(E1), dihydrolipoamide acetyltransferase(E2), and dihydrolipoamide dehydrogenase (E3). Two regulatory components (E1-kinase and phospho-E1 phosphatase) and functionally less-understood protein (protein X, E3BP) are also involved in the formation of the complex. In this study, cloning and characterization of a gene for human E3BP have been carried out. A cDNA encoding the human E3BP was isolated by database search and cDNA library screening. The primary structure of E3BP has some similar characteristics with that of E2 in the lipoyl domain and the carboxyl-terminal domain, based on the nucleotide sequence and the deduced amino acid sequence. However, the conserved amino acid moiety including the histidine residue for acetyltransferase activity in E2 is not conserved in the case of human E3BP. The human E3BP was expressed and purified in E. coli. The molecular weight of the protein, excluding the mitochondrial target sequence, was about 50 kDa as determined by SDS-PAGE. Cloning of human E3BP and expression of the recombinant E3BP will facilitate the understanding of the role(s) of E3BP in mammalian PDC.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.843-848
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• 1996

Porous resin beads of Poly(styrene-co-divinylbenzene) have been prepared by suspension polymerization. The bead could be made porous in the region above 30wt% of the crosslinking agent(divinylbenzene ) and the porogenic agent(toluene), respectively. The specific surface area of porous beads increased with increasing the concentrations of divinylbenzene and toluene. The specific surface area of the porous resin bead decreased, when sulfonated with concentrated sulfuric acid. The catalytic activity of sulfonated resin catalyses increased with increasing the degree of crosslinking in the liquid-phase reesterification of ethyl acetate with 1-propanol. The adsorbed quantity of sodium dodecylbenzene sulfonate in an aqueous solution also increased with increasing surface area of porous resins.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.649-655
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• 2013

Methanol was directly produced by the partial oxidation of methane with perovskite and mixed oxide catalysts. Perovskite ($ABO_3$) catalysts were prepared by the malic acid method with changing A and B site components. Three-component mixed oxide catalysts that have Mo and Bi as a main component were prepared by the co-precipitation method. Among the perovskite catalysts, $SrCrO_3$ showed the highest methanol selectivity of 11% at $400^{\circ}C$. For the three-component mixed oxide catalysts, there were no remarkable changes in methane conversion. Among the mixed oxide catalysts, Mo-Bi-Cr mixed oxide catalyst showed the highest methanol selectivity of 15.3% at $400^{\circ}C$. The catalytic activity and methanol selectivity of the three-component mixed oxide catalysts were directly proportional to the surface area of the catalysts.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.171-171
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• 2009

The electrodes are usually made of a porous mixture of carbon-supported platinum and ionomers. $SnO_2$ particles provide as supports that have been used for DMFCs, and it have high catalytic activities toward methanol oxidation. The main advantage of $SnO_2$ supported electrodes is that it has strong chemical interactions with metallic components. The high activity to a synergistic bifunctional mechanism in which Pt provides the adsorption sites for CO, while oxygen adsorbs dissociative on $SnO_2$. The reaction between the adsorbed species occurs at the Pt/$SnO_2$ boundary. The morphological observations were characterized by FESEM and transmission electron microscopy (TEM). $SnO_2$ particles crystallinity was analyzed by the X-ray diffraction (XRD). The surface bonded state of the $SnO_2$ particles and electrode materials were observed by the X-ray photoelectron spectroscopy (XPS). The electric properties of the Pt/$SnO_2$ catalyst for methanol oxidation have been investigated by the cyclic voltametry (CV) in 0.1M $H_2SO_4$ and 0.1M MeOH aqueous solution. The peak current density of methanol oxidation was increased as the $SnO_2$ content in the anode catalysts increased. Pt/$SnO_2$ catalysts improve the removal of CO ads species formed on the platinum surface during methanol electro-oxidation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.52-59
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• 1999

Vegetation canopy plays an important role in $CO_2$/$H_2$O exchange between the biosphere and the atmosphere by controlling leaf stomata. In this study, rice (Oryza sativa L.), a staple crop in Asia was investigated to formulate its single leaf model of photosynthesis and stomatal conductance. Photosynthesis and stomatal conductance were measured with a portable infrared gas analyzer system. Other plant and meteorological variables were also measured. To evaluate empirical constants in this biochemical leaf model, nonlinear least squares technique was used. The maximum catalytic activity of enzyme and the maximum rate of electron transport were $ 100\mu$㏖ $m^{-2}$ $s^{-1}$ and $140 \mu$㏖ m$^{-2}$ s$^{-1}$ (@ 35$^{\circ}C$), respectively. The empirical constants, m and b, associated with stomatal conductance model were 9.7 and $0.06 m^{-2}$ $s^{-1}$ , respectively. On a leaf scale, agreements between the modeled and the measured values of photosynthesis and stomatal conductance were on average within 20%, and the simulation of diurnal variation was also satisfactory On a canopy scale, the Simple Biosphere model(SiB2) was tested using the derived parameters. The modeled energy fluxes were compared against the micrometeorologically measured fluxes over a rice canopy. Agreements between the modeled and the measured values of net radiation, sensible heat and latent heat fluxes, and $CO_2$ flux (i.e., net canopy photosynthesis) were on average within 25%.

• Korean Journal of Materials Research
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• v.32 no.2
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• pp.98-106
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• 2022

Metal-organic frameworks (MOFs) are widely used in various fields because they make it easy to control porous structures according to combinations of metal ions and organic linkers. In addition, ZIF (zeolitic imidazolate framework), a type of MOF, is made up of transition metal ions such as Co²⁺ or Zn²⁺ and linkers such as imidazole or imidazole derivatives. ZIF-67, composed of Co²⁺ and 2-methyl imidazole, exhibits both chemical stability and catalytic activity. Recently, due to increasing need for energy technology and carbon-neutral policies, catalysis applications have attracted tremendous research attention. Moreover, demand is increasing for material development in the electrocatalytic water splitting and metal-air battery fields; there is also a need for bifunctional catalysts capable of both oxidation/reduction reactions. This review summarizes recent progress of bifunctional catalysts for electrocatalytic water splitting and metal-air batteries using ZIF-67. In particular, the field is classified into areas of thermal decomposition, introduction of heterogeneous elements, and complex formation with carbon-based materials or polyacrylonitrile. This review also focuses on synthetic methods and performance evaluation.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.29-33
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• 2010

In this study, boron, carbon, nitrogen and fluorine co-doped $TiO_{2}$ photocatalysts using tetraethylammonium tetrafluoroborate (TEATFB) have been prepared by different heat treatment temperatures to decrease the band gap. To explore the visible light photocatalytic activity of the novel low‐zband gap $TiO_{2}$ photocatalyst, the removal of two dyes was investigated, namely, acridine orange and rhodamine B. XRD patterns demonstrate that the samples calcined at temperatures up to $800^{\circ}C$ clearly show anatase peaks. The XPS results show that all the doped samples contain N, C, B and F elements and the doped $TiO_{2}$ shows the shift in the band gap transition down to 2.98 eV as UV-DRS results. In these UV-Vis results, photocatalytic activity of the doped $TiO_{2}$ is 1.61 times better than undoped $TiO_{2}$. Specially, excellent photoactivity results were obtained in the case of samples treated at $700^{\circ}C$.