• Journal of the Korean Applied Science and Technology
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• v.19 no.3
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• pp.213-221
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• 2002

Activated carbons with high surface area of 2,600 $m^{2}/g$ and high pore volume of 1.2 cc/g could be prepared by KOH activation of rice hulls at a KOH:char ratio of 4:1 and $850^{\circ}C$. In order to increase the adsorption capacity of hydrogen sulfide, which is one of the major malodorous component in the waste water treatment process, various contents of $Na_{2}CO_{3}$ and $KIO_{3}$ were impregnated to the rice-hull activated carbon. The impregnated activated carbon with 5 wt.% of $Na_{2}CO_{3}$ showed improved $H_{2}S$ adsorption capacity of 75 mg/g which is twice of that for the activated carbon without impregnation and the impregnated activated carbon with 2.4 wt.% of $KIO_{3}$ showed even higher $H_{2}S$ adsorption capacity of 97 mg/g. The improvement of $H_{2}S$ adsorption capacity by the introduction of those chemicals could be due to the $H_{2}S$ oxidation and chemical reaction with impregnated materials in addition to the physical adsorption of activated carbon.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.576-583
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• 2023

This study investigated the possibility of new adsorbent materials made from pig bone-based biomass. To this end, the properties of pig bone-based activated carbon (PAC) prepared from animal biomass were investigated, and its carbon dioxide adsorption performance was examined. KOH was used as the activation agent, and the specific surface area increased with increasing activation temperature, and the adsorption efficiency of carbon dioxide also increased. The sample activated at 800 ℃ exhibited the largest specific surface area of 1208.7 m²/g and the highest CO₂ adsorption efficiency of 3.33 mmol/g at 273 K, 1 bar. However, the specific surface area and the CO₂ adsorption efficiency decreased at activation temperatures above 900 ℃ due to crystallinity changes and overactivation. On the other hand, when the selectivity was calculated using the ideal adsorption solution theory, PAC-900 samples at 273 K and below 0.8 bar showed the best selectivity. These results suggest that the high selectivity of carbon dioxide/nitrogen adsorption at 273 K is due to the carbon dioxide adsorption capacity of hydroxyapatite formed by the decomposition of carbonate when pig bone is activated at 900 ℃ and its crystallinity.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1729-1733
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• 2012

The solvolysis rate constants of 2,2,2-trichloroethyl chloroformate ($Cl_3CCH_2OCOCl$, $\mathbf{3}$) in 30 different solvents are well correlated with the extended Grunwald-Winstein equation, using the $N_T$ solvent nucleophilicity scale and the $Y_{Cl}$ solvent ionizing scale, with sensitivity values of $1.28{\pm}0.06$ and $0.46{\pm}0.03$ for $l$ and $m$, respectively. The activation enthalpies (${\Delta}H^{\neq}$) are 10.1 to 12.8 $kcal{\cdot}mol^{-1}$ and the activation entropies (${\Delta}S^{\neq}$) are -27.8 to -36.8 $cal{\cdot}mol^{-1}{\cdot}K^{-1}$, which is consistent with the proposed bimolecular reaction mechanism. The kinetic solvent isotope effect ($k_{MeOH}/k_{MeOD}$) of 2.39 is also in accord with $S_N2$ mechanism probably assisted by general-base catalysis.

• BMB Reports
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• v.53 no.2
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• pp.88-93
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• 2020

Cisplatin is a widely used anti-cancer agent. However, the effectiveness of cisplatin has been limited by the commonly developed drug resistance. This study aimed to investigate the potential effects of endoplasmic reticulum (ER) stress to overcome drug resistance using the cisplatin-resistant A2780/CisR ovarian cancer cell model. The synthetic chalcone derivative (E)-3-(3,5-dimethoxyphenyl)-1-(2-methoxyphenyl)prop-2-en-1-one (named DPP23) is an ER stress inducer. We found that DPP23 triggered apoptosis in both parental cisplatin-sensitive A2780 and cisplatin-resistant A2780/CisR ovarian cancer cells due to activation of reactive oxygen species (ROS)-mediated unfolded protein response (UPR) pathway in the endoplasmic reticulum. This result suggests that ROS-mediated UPR activation is potential in overcoming drug resistance. DPP23 can be used as a target pharmacophore for the development of novel chemotherapeutic agents capable of overcoming drug resistance in cancer cells, particularly ovarian cancer cells.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1897-1901
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• 2011

This report shows the rates of solvolyses for phenyl methanesulfonyl chloride ($C_6H_5CH_2SO_2Cl$, I) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are reported. Three representative solvents, studies were made at several temperatures and activation parameters were determined. The thirty kinds of solvents gave a reasonably precise extended Grunwald-Winstein plot, coefficient (R) of 0.954. The sensitivity values (l = 0.61 and m = 0.34, l/m = 1.8) of phenyl methanesulfonyl chloride (I) were smaller than those obtained for benzenesulfonyl chloride ($C_6H_5SO_2Cl$, II; l = 1.01 and m = 0.61) and 2-propanesulfonyl chloride ($(CH_3)_2CHSO_2Cl$, III; l = 1.28 and m = 0.64). As with the two previously studied solvolyses, an $S_N2$ pathway with somewhat ionization reaction is proposed for the solvolyses of I. The activation parameters, ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$, were determined and they are also in line with values expected for a bimolecular reaction mechanism. The kinetic solvent isotope effect of 2.34 in $CH_3OH/CH_3OD$ is in accord with a bimolecular mechanism, probably assisted by general-base catalysis.

• Journal of Microbiology
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• v.39 no.3
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• pp.186-194
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• 2001

Scrub typhus, caused by Orientia tsutsugamushi infection, is clinically and histopathologically characterized by local as well as systemic inflammatory reactions, indicating that orientiae induce mechanisms that amplify the inflammatory response. To reveal underlying mechanisms of chemoattraction and activation of responding leukocytes, expression of chemokine and tumor necrosis factor alpha (TNF-$\alpha$) genes in murine peritoneal macrophages after infection with the obligate intracellular bacterium Ο.tsutsugamushi was investigated. The genes that were unregulated included macrophage inflammatory proteins l$\alpha$/$\beta$(MIP-l$\alpha$/$\beta$), MIP-2, monocyte chemoattractant protein 1(MCP-1), RANTES (regulated upon activation, normal T-cell expressed and secreted), gamma-interferon-inducible protein 10(IP-10) and TNF-$\alpha$. Peak expression of these chemokines and TNF-$\alpha$ was observed between 1 and 3 h after infection. These responses returned to or approached baseline preinfection levels 6 h after challenge. Semiquantitative reverse transcription (RT)-PCR analysis revealed dramatic Increases during infection in the steady-state levels of mRNA ceding for the inhibitory subunit of NF-kB (IkB$\alpha$), whose transcription is enhanced by binding of NF-kB within the IkB$\alpha$promoter region. Thus, Ο. tsutsugamushi appears to be a stung inducer of chemokines and TNF-$\alpha$ which may significantly contribute to inflammation and tissue damage observed in scrub typhus by attracting and activating phagocytic leukocytes.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1927-1931
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• 2008

Rate of solvolysis of diphenylthiophosphinyl chloride in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2-trifluoroethanol (TFE) or 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) are reported. Solvolyses were also carried out in TFE-ethanol mixtures. For five representative solvents, studies were made at several temperatures and activation parameters determined. The 29 solvents gave a reasonably precise extended Grunwald-Winstein equation plot, correlation coefficient (R) of 0.933, which improved to 0.983 when the four TFE-ethanol points were excluded. The sensitivities (l = 1.00 and m = 0.64) were similar to those obtained for dimethyl phosphorochloridate and phosphorochloridothionate and diphenylphosphinyl chloride (1). As with the four previously studied solvolyses, an $SN_2$ pathway is proposed for the solvolyses of diphenylthiophosphinyl chloride. The activation parameters, ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$, were determined and they are also in line with values expected for an $S_N2$ reaction.

• Carbon letters
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• v.15 no.3
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• pp.192-197
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• 2014

A hierarchical pore structured novolac-type phenol based-activated carbon with micropores and mesopores was fabricated. Physical activation using a sacrificial silicon dioxide ($SiO_2$) template and chemical activation using potassium hydroxide (KOH) were employed to prepare these materials. The morphology of the well-developed pore structure was characterized using field-emission scanning electron microscopy. The novolac-type phenol-based activated carbon retained hierarchical pores (micropores and mesopores); it exhibited high Brunauer-Emmett-Teller specific surface areas and hierarchical pore size distributions. The hierarchical pore novolac-type phenol-based activated carbon was used as an electrode in electric double-layer capacitors, and the specific capacitance and the retained capacitance ratio were measured. The specific capacitances and the retained capacitance ratio were enhanced, depending on the $SiO_2$ concentration in the material. This result is attributed to the hierarchical pore structure of the novolac-type phenol-based activated carbon.

• Korean Journal of Materials Research
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• v.25 no.4
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• pp.191-195
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• 2015

To improve its textural properties as a support for platinum catalyst, carbon aerogel was chemically activated with KOH as a chemical agent. Carbon-supported platinum catalyst was subsequently prepared using the prepared carbon supports(carbon aerogel(CA), activated carbon aerogel(ACA), and commercial activated carbon(AC)) by an incipient wetness impregnation. The prepared carbon-supported platinum catalysts were applied to decalin dehydrogenation for hydrogen production. Both initial hydrogen evolution rate and total hydrogen evolution amount were increased in the order of Pt/CA < Pt/AC < Pt/ACA. This means that the chemical activation process served to improve the catalytic activity of carbon-supported platinum catalyst in this reaction. The high surface area and the well-developed mesoporous structure of activated carbon aerogel obtained from the activation process facilitated the high dispersion of platinum in the Pt/ACA catalyst. Therefore, it is concluded that the enhanced catalytic activity of Pt/ACA catalyst in decalin dehydrogenation was due to the high platinum surface area that originated from the high dispersion of platinum.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.383-388
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• 2009

Rates of solvolyses of diphenyl thiophosphorochloridate ($(PhO)_2$PSCl, 1) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone and 2,2,2-trifluoroethanol (TFE) are reported. For four representative solvents, studies were made at several temperatures and activation parameters were determined. The 30 solvents gave a reasonably precise extended Grunwald-Winstein plot, correlation coefficient (R) of 0.989. The sensitivity values (l = 1.29 and m = 0.64) of diphenyl thiophosphorochloridate ($(PhO)_2$PSCl, 1) were similar to those obtained for diphenyl phosphorochloridate ($(PhO)_2$POCl, 2), diphenylphosphinyl chloride ($Ph_2$POCl, 3) and diphenylthiophosphinyl chloride ($Ph_2$PSCl, 4). As with the previously studied of 3~4 solvolyses, an $S_N$ pathway is proposed for the solvolyses of diphenyl thiophosphorochloridate (1). The activation parameters, ${\Delta}H^{\neq}\;(=11.6{\sim}13.9\;kcal{\cdot}mol^{-1})\;and\;{\Delta}S^{\neq}\; (=\;-32.1\;{\sim}\;-42.7\;cal{\cdot}mol^{-1}{\cdot}K^{-1})$, were determined, and they were in line with values expected for an $S_N$2 reaction. The large kinetic solvent isotope effects (KSIE, 2.44 in MeOH/MeOD and 3.46 in $H_2O/D_2$O) are also well explained by the proposed $S_N$2 mechanism.