• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.3 s.116
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• pp.79-84
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• 2006

Hydrogen peroxide has been a bleaching chemical for varied pulp, especially mechanical and deinking pulp. It is catalytically decomposed by some transition metals in pulp slurry. In this paper, some metals which can be contained in pulp such as manganese, copper, iron, magnesium and calcium were used to investigate their effect on the decomposition of hydrogen peroxide. From the result, hydrogen peroxide was more decomposed in the order of Mn, Cu, $Fe^{3+}\;and\;Fe^{2+}$, while Mg and Ca had little effect on the decomposition of hydrogen peroxide. The effect of Mg/Mn ratio on the decomposition of hydrogen peroxide was also investigated. At the specific ratio of them(Mg/Mn=10), hindering effect of peroxide decomposition by Mg was decreased.

• Macromolecular Research
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• v.17 no.5
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• pp.346-351
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• 2009

$TiCl(O-i-Pr)_3/SiO_2$ and $Ti(O-i-Pr)_4/SiO_2$ were prepared by immobilizing chlorotitanium (IV) isopropoxide ($TiCl(O-i-Pr)_3$) and titanium (IV) isopropoxide ($Ti(O-i-Pr)_4$), to pretreated silica. The effect of the polymerization reaction conditions on the catalytic activity and characteristics of the resulting PLA were investigated. The catalytic conversion, molecular weight and polydispersity index (PDI) of the PLA produced on the titanium alkoxide supported catalysts increased proportionally with the reaction temperature. When the PLA was synthesized in bulk polymerization, the PLA produced with the supported catalysts had higher molecular weight than those with homogeneous catalysts. The melting temperature of the polymer produced with silica supported alkoxide catalysts was approximately $170-180^{\circ}C$.

• BMB Reports
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• v.43 no.4
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• pp.263-267
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• 2010

To characterize the biochemical properties of the PP2A regulatory B subunit, PPP2R5D, we analyzed its phosphorylation sites, stoichiometry and effect on holoenzyme activity. PPP2R5D was phosphorylated on Ser-53, Ser-68, Ser-81, and Ser-566 by protein kinase A, and mutations at all four of these sites abolished any significant phosphorylation in vitro. In HEK293 cells, however, the Ser-566 was the major phosphorylation site after PKA activation by forskolin, with marginal phosphorylation on Ser-81. Inhibitory tyrosine phosphorylation on Tyr-307 of the PP2A catalytic C subunit was decreased after forskolin treatment. Kinetic analysis showed that overall PP2A activity was increased with phosphorylation by PPP2R5D phosphorylation. The apparent Km was reduced from $11.25\;{\mu}M$ to $1.175\;{\mu}M$ with PPP2R5D phosphorylation, resulting in an increase in catalytic activity. These data suggest that PKA-mediated activation of PP2A is enabled by PPP2R5D phosphorylation, which modulates the affinity of the PP2A holoenzyme to its physiological substrates.

• Resources Recycling
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• v.13 no.3
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• pp.27-36
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• 2004

Nickel oxide was recovered through roasting of a spent catalyst for hydrogenation reaction. Nickel on Kieselguhr catalysts were prepared by a precipitation method after a treatment of the recovered-nickel oxide with an acid. Effects of roasting temperature of the spent catalyst on recovery of nickel oxide was investigated. Most of nickel oxide could be recovered through roasting of the spent catalyst at $1000^{\circ}C$. In regeneration of catalysts by the precipitation method after the treatment of nickel oxide with an acid, the effect of promoter, precipitation condition and reduction condition on catalytic performance in vegetable oil hydrogenation were investigated. The addition of CaO or $Ce_2$$O_3$ resulted in an increase of catalytic activity.

• BMB Reports
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• v.38 no.6
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• pp.676-682
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• 2005

To date, no 8-oxoguanine-specific endonuclease-coding gene has been identified in Thermotoga maritima of the order Thermotogales, although its entire genome has been deciphered. However, the hypothetical protein Tm1821 from T. maritima, has a helix-hairpin-helix motif that is considered to be important for DNA binding and catalytic activity. Here, Tm1821 was overexpressed in Escherichia coli and purified using Ni-NTA affinity chromatography, protease digestion, and gel filtration. Tm1821 protein was found to efficiently cleave an oligonucleotide duplex containing 8-oxoguanine, but Tm1821 had little effect on other substrates containing modified bases. Moreover, Tm1821 strongly preferred DNA duplexes containing an 8-oxoguanine:C pair among oligonucleotide duplexes containing 8-oxoguanine paired with four different bases (A, C, G, or T). Furthermore, Tm1821 showed AP lyase activity and Schiff base formation with 8-oxoguanine in the presence of $NaBH_4$, which suggests that it is a bifunctional DNA glycosylase. Tm1821 protein shares unique conserved amino acids and substrate specificity with an 8-oxoguanine DNA glycosylase from the hyperthermophilic archaeon. Thus, the DNA recognition and catalytic mechanisms of Tm1821 protein are likely to be similar to archaeal repair protein, although T. maritima is an eubacterium.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.335-338
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• 2007

Cost effectiveness is an important parameter for producing DSSCs as compared to the widely used conventional silicon based solar cells. A fluorine-doped tin oxide (FTO) substrate coated with a catalytic amount of platinum is used as counter electrode in dye-sensitized solar cell. Carbonaceous materials are quite attractive to replace platinum due to their high electronic conductivity, corrosion resistance towards $I_{2}$, good catalytic effect and low cost. In this paper, the unit DSSCs with Pt and CNT as a counter electrode were connected in series-parallel externally, then the current-voltage curves were investigated to find out the connection characteristics of the DSSC with CNT counter electrode. The connection characteristics of the DSSC with CNT counter electrode is superior to that of the DSSC with Pt counter electrode. And a parallel connection of the DSSC with CNT counter electrode has higher efficiency than a series connection of that.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.388-391
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• 2006

A fluidized bed reactor made of quartz with 0.055m I.D. and 1.0m in height was employed for the thermocatalytic decomposition of propane to produce $CO_2-free$ hydrogen. The fluidized bed was proposed for the continuous withdraw of product carbons from the reactor The propane decomposition rate used carbon black DCC-N330, Hi-900L as a catalyst. The propane decomposition reaction was carried out at the temperature range of $600-800^{\circ}C$, propane gas velocity of $1.0U_{mf}$ and the operating pressure of 1.0 atm. Effect of operating parameters such as reaction temperature on the reaction rates was investigated. Resulting production in our experiment were not only hydrogen but also several by products such as methane, ethylene, ethane, and propylene.

• Journal of the Korean Society of Combustion
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• v.12 no.3
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• pp.16-23
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• 2007

Employing an after-treatment system has almost become a mandatory requirement for Diesel vehicles, which results from a reinforced exhaust regulations as the number of vehicles powered by a Diesel engine increases. The Diesel Particulate Filter (DPF) system is considered as one of the most efficient method to reduce particulate matter (PM); however, the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas composition and flow rate of exhaust gas are important parameters in DPF evaluation processes, especially during a regeneration process. Engine dynamometer and segment tester are generally used in DPF evaluation so far. These test methods, however, could not completely evaluate the effect of various parameters on real DPF, such as oxygen concentration, amount of soot and exhaust gas temperatures. The evaluation of DPF systems using a dump combustor has been verified experimentally and this dump combustor system is likely to be appropriate for the DOC (Diesel Oxidation Catalyst) and SCR (Selective Catalytic Reduction) assessments test, too.

• Journal of the Korean Applied Science and Technology
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• v.24 no.3
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• pp.272-277
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• 2007

Catalytic activity changes of perovskite catalysts were examined with their A-site substitution. For the preparation of catalysts, Mn was used for B-site component and La, Ce, Sr, Ba, Ca, Ag were used for A-site component of the perovskite $catalysts(ABO_3)$ The effect of calcination temperature on methane combustion and perovskite structure was also investigated. The surface area and adsorbed oxygen species were tested with BET apparatus and $O_2-TPD$, respectively. Perovskite catalysts whose A-site was partially substituted needed higher calcination temperature than un-substituted one to form the perovskite structure. From $O_2-TPD$ experiment, it was found that methane combustion activity was directly related to the oxygen desorbing ability of the catalysts. The prepared catalyst(LM-7) was stable at $600^{\circ}C$ for 72 hours of reaction.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.318-324
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• 1998

A ${\beta}$-galactosidase with high transgalactosylic activity was purified from a Bacillus species, registered as KFCC10855. The enzyme preparation showed a single protein band corresponding to a molecular mass of 150 kDa on SDS-PAGE and gave a single peak with the estimated molecular mass of 250 kDa on Sephacryl S-300 gel filtration, suggesting that the enzyme is a homodimeric protein. The amino acid and sugar analyses revealed that the enzyme is a glycoprotein, containing 19.2 weight percent of sugar moieties, and is much more abundant in hydrophilic amino acid residues than in hydrophobic residues, the mole ratio being about 2:1. The pI and optimum pH were determined to be 5.0 and 6.0, respectively. Having a temperature optimum at $70^{\circ}C$ for the hydrolysis of lactose, the enzyme showed good thermal stability. The activity of the enzyme preparation was markedly increased by the presence of exogenous Mg (II) and was decreased by the addition of EDTA. Among the metal ions examined, the most severely inhibitory effect was seen with Ag (I) and Hg (II). Further, results of protein modification by various chemical reagents implied that 1 cysteine, 1 histidine, and 2 methionine residues occur in certain critical sites of the enzyme, most likely including the active site. Enzyme kinetic parameters, measured for both hydrolysis and transgalactosylation of lactose, indicated that the enzyme has an excellent catalytic efficiency for formation of the transgalactosylic products in reaction mixtures containing high concentrations of the substrate.