• The Journal of Natural Sciences
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• v.15 no.1
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• pp.57-67
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• 2005

In Order to investigate the physiological role of thiol peroxidase in Bacillus subtilis, a thiol peroxidase (btpx) knock-out mutant was generated by homologous recombination. The growth of btpx knock-out mutant in aerobic condition showed a similar pattern with that of wild type of Bacillus subtilis 168/ But btpx knock-out mutant showed a retarded growht in response to oxidative stress such as $H_2O_2$, cumene hydroperoxide (CHP) treatments.

• Bulletin of the Korean Chemical Society
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• v.22 no.12
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• pp.1309-1315
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• 2001

Zirconium sulfate supported on zirconia catalysts were prepared by impregnation of powdered $Zr(OH)_4$ with zirconium sulfate aqueous solution followed by calcining in air at high temperature. The characterization of prepared catalysts was performed using Fourier transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and by the measurement of surface area. The addition of zirconium sulfate to zirconia increased the phase transition temperature of $ZrO_2$ from amorphous to tetragonal due to the interaction between zirconium sulfate and zirconia, and the specific surface area and acidity of catalysts increased in proportion to the zirconium sulfate content up to 10 wt% of $Zr(SO_4)_2$. Infrared spectra of ammonia adsorbed on $Zr(SO_4)2}ZrO_2$ showed the presence of Bronsted and Lewis acid sites on the surface. $10-Zr(SO_4)_2}ZrO_2$ calcined at $600^{\circ}C$ exhibited maximum catalytic activities for 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acidity of catalysts measured by ammonia chemisorption method.

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.564-573
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• 2014

Economic optimization of cumene manufacturing process to produce cumene from benzene and propylene was studied. The chosen objective function was the operational profit per year that subtracted capital cost, utility cost, and reactants cost from product revenue and other benefit. The number of design variables of the optimization are 6. Matlab connected to and controlled Unisim Design to calculate operational profit with the given design variables. As the first step of the optimization, design variable points was sampled and operational profit was calculated by using Unisim Design. By using the sampled data, the estimation model to calculate the operational profit was constructed, and the optimization was performed on the estimation model. This study compared second order polynomial and support vector regression as the estimation method. As the sampling method, central composite design was compared with Hammersley sequence sampling. The optimization results showed that support vector regression and Hammersley sequence sampling were superior than second order polynomial and central composite design, respectively. The optimized operational profit was 17.96 MM$ per year, which was 12% higher than 16.04 MM$ of base case.

• BMB Reports
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• v.32 no.3
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• pp.226-231
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• 1999

In vitro effects of acetone on cytochrome P450 (P450)-dependent benzo(a)pyrene (B(a)P) hydroxylation supported by cumene hydroperoxide (CuOOH) or NADPH/$O_2 $ systems were studied using 3-methylcholanthrene-pretreated rat liver microsomes. The maximal rate of B(a)P hydroxylation at constant concentration ($80\;{\mu}M)$ of the substrate was observed in the presence of $30\;{\mu}M$ CuOOH. However, at concentrations higher than $30\;{\mu}M$ CuOOH the hydroxylation rates were rapidly decreased. In contrast to CuOOH, at a concentration of $200\;{\mu}M$ NADPH, B(a)P hydroxylation rate reached a plateau. At concentrations higher than $200\;{\mu}M$ NADPH, the rates of substrate hydroxylation were maintained at the maximal rate with no inhibition. Acetone at 1% (v/v) enhanced both CuOOH- and NADPH/$O_2$-supported B(a)P hydroxylation at the optimal concentrations of the cofactors. At concentrations higher than 1% (v/v) acetone, substrate hydroxylation was sterero specific under the support of these two cofactors; it was strongly enhanced with $30\;{\mu}M$ CuOOH, but rather inhibited in the $200\;{\mu}M$> NADPH/$0_2 $ system. The lipid peroxidation rate induced during CuOOH-supported P450-dependent B(a)P hydroxylation was increased as CuOOH concentrations were increased. Acetone in the concentration range of 2.5~7.5%(v/v) inhibited lipid peroxidation during CuOOH supported B(a)P hydroxylation. The finding that CuOOH-supported B(a)P hydroxylation is greatly enhanced by acetone suggests that acetone may contribute more to the activation of oxygen (for the insertion of oxygen into the substrate) in the presence of CuOOH than with NADPH/$O_2$. Acetone may also contribute to the partial inhibition of destruction of microsomal membranes by lipid peroxidation.

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.35-43
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• 1990

A series of $TiO_2-SiO_2$catalysts were prepared by coprecipitation from the mixed solution of titanium tetrachloride and sodium silicate. Some of the samples were treated with 1N $H_2SO_4$ and used as modified catalysts. The catalytic activities of modified catalysts were higher than those of unmodified catalysts, and the effect of modification on the catalytic activity was higher for 2 - propanol dehydration than for cumene dealkylation. The catalytic activity of unmodified catalysts was correlated with their acid amount for the above two reactions. As $TiO_2-SiO_2$ catalysts had relatively large amount of weak acid sites and small amount of strong acid sites, the catalytic activity for 2 - propanol dehydration was higher than that for cumene dealkylation. The effect of modification on catalytic activity increased with increasing $TiO_2$content of the catalysts. Actually, $92-TiO_2-SiO_2/SO_4{^2}$had the highest increment in catalytic activity and $10-TiO_2-SiO_2/SO_4{^2}$had the lowest increment for the 2 - propanol dehydration.

• Bulletin of the Korean Chemical Society
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• v.24 no.2
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• pp.159-160
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• 2003

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.245-251
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• 1996

A series of $BeO-SiO_2$ catalysts were prepared by coprecipitation from the mixed solution of berylium chloride and sodium silicate. The addition of BeO to $SiO_2$ caused the increased of acidity, acid strength, specific surface area, and acid catalytic activity, giving a maximum at 20 mol% of BeO. On the basis of x-ray diffraction pattern, the catalysts calcined at $400{\sim}500^{\circ}C$ were found to be amorphous, having both $Br{\ddot{o}}nsted$ and Lewis acid sites. Catalytic activities for cumene dealkylation were closely correlated with the acidity of catalysts.

• Journal of the Korean Applied Science and Technology
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• v.5 no.1
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• pp.25-30
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• 1988

In order to develope the method of quantitative determination of lipid hydroperoxide in human blood serum, we tried the ferrothiocyanate method to total lipids extracted by Bligh-Dyer method and obtained the results as follows. 1. The maximum absorbance showed at the concentration of Mohr's solution, 0.127M at pH 1.70 and ammonium thiocyanate solution, 3.95M in the ferrothiocyanate method. 2. When hydrogen peroxide, cumene hydroperoxide, and oxidized linoleic acid were added to serum, and extracted them by Bligh-Dyer method to examine the extraction efficiency, we confirmed that cumene hydroperoxide and oxidized linoleic acid were extracted in $CHCI_3$ phase, and hydrogen peroxide in $MeOH-H_2O$ phase, respectively. 3. The concentration of lipid hydroperoxide of total lipids extracted from normal adult serum was $2.0{\times}10^{-5}M$, and increased proportionally the concentration of lipid hydroperoxide by increasing the amount of serum. 4. When we compared the total lipids extracted by Bligh-Dyer method and total lipids extracted after lipoprotein is precipitated by Yagi method in human blood serum, the concentration of lipid hydroperoxide was showed nearly the same value. From our results, we concluded that the concentration of lipid hydroperoxide in human blood serum could be determined quantitatively by ferrothiocyanate method.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.657-664
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• 2004

Titanium sulfate supported on $TiO_2$was prepared by impregnation of powdered $TiO_2$with an aqueous solution of titanium sulfate followed by calcining in air at high temperature. For Ti$(SO_4)_2/TiO_2$ samples calcined at 300 $^{\circ}C$, no diffraction lines of titanium sulfate are observed at $Ti(SO_4)_2$loading up to 30 wt%, indicating good dispersion of $Ti(SO_4)_2$ on the surface of $TiO_2$. The acidity of the catalysts increased in proportion to the titanium sulfate content up to 20 wt% of $Ti(SO_4)_2$. 20 wt% $Ti(SO_4)_2/TiO_2$ calcined at 300 $^{\circ}C$ exhibited maximum catalytic activities for 2-propanol dehydration and cumene dealkylation. The catalytic activities for these reactions, were correlated with the acidity of catalysts measured by ammonia chemisorption method.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.2
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• pp.178-182
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• 1998

Previously, we showed that acetone enhanced aryl hydrocarbon hydroxylase (AHH) activity in only 3-methylcholanthrene (MC)- or $\beta$-naphtoflavone (BNF)-inducible microsomes of rat liver. In the present study, the possible mechanism underlying acetone action on AHH was investigated in the liver microsomes from MC-pretreated rats. Other n-alkylketones except acetone did not increase AHH activity, which rather decreased significantly with the length of alkyl side chain. Acetone had no effect on the activity of NADPH-cytochrome P450 reductase or inhibited the formation of 3-OH benzo(a)pyrene (B(a)P) in nonenzymatic model ascorbic acid system. However, in cumene hydroperoxide (CuOOH)-supported B(a)P hydroxylation, acetone enhanced its velocity remarkably by 30% at the optimal concentration (30 $\mu$M CuOOH and 1.0% acetone). From these results, we conclude that acetone may facilitate the formation of an activated oxygen species or the insertion of oxygen into B(a)P molecule in CYP1A rich microsomes.