• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.261-269
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• 2005

The object of this research is to produce alkali activated fly ash-cement using low calcium fly ash as substitute for portland cement. The experimental program included activation of fly ash by a strong base(NaOH) at different concentration, temperature, and liquid-to-fly ash ratios. To achieve for higher compressive strength of the hardened product, sodium meta silicate is added to the alkaline solution. From the factors considered on strength development, the ratio of liquid/fly ash, the activator concentration and temperature always result to be significative factors. The optimization studied show that the alkaline solution concentration of $NaOH(210g)+Na_2SiO_3{\cdot}9H_2O(30g)+H_2O=1L$ at $50^{\circ}C$ produces the best alkali activation effect for the low calcium fly ash. SEM and XRD patterns showed that the components of alkali-activated fly ash consist mainly of mullite, quartz and amorphous aluminosilicate.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.1
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• pp.76-83
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• 2009

Rehmannia Radix Preparata (RRP) used to nourish Eum and enrich blood for consumptive fever, aching, and limpness of the loins and knees, and to replenish essence for tinnitus, premature greying of beard and hair. In the present study, we studied about the protective effect of RRP on hydrogen peroxide-induced oxidative stress in human vascular endothelial cells. ECV304 cells were preincubated with RRP (100, 200, 300 and $400{\mu}g/m{\ell}$) for 12hr and then treated with $600{\mu}M$ $H_2O_2$ for 12hr. The protective effects of RRP on $H_2O_2$-induced apoptosis in ECV304 cells was determined by using MTT assay, FDA-PI staining, flow cytometric analysis, caspase-3 activity assay, ROS assay and western blot. The results of this experiment showed that RRP inhibited $H_2O_2$-induced apoptosis and ROS production in ECV304 cells. Moreover, RRP increased ERK activation that decreased in $H_2O_2$-treated ECV304 cells, and inhibited p38 and JNK activation. Furthermore, RRP increased expression of heme oxygenase-1 (HO-1) in $H_2O_2$-treated ECV304 cells. Also, HO-1 protein expression induced by RRP was reduced by the addition of ERK inhibitor (PD98059) in $H_2O_2$-treated ECV304 cells. These results suggest that protective effect of RRP on $H_2O_2$-induced oxidative stress in ECV304 cells may be associated with increase of ERK activation and HO-1 protein, and reduction of p38 and JNK activation.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.242.1-242.1
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• 2002

H$_2$O$_2$ has been shown to act as a signaling molecule involved in many cellular functions such as oxidant-induced stress, apoptosis, proliferation. In this study, we investigated the action mechanisms of H$_2$O$_2$ on activation of Extracellular Signal-Regulated Protein Kinase(ERK) in cultured feline ileal smooth muscle cells(ISMC). Western blot analysis done with phospho-specific MAP kinases antibodies demonstrated that potent activation of ERK and moderate activation of SAPK/JNK occurred within 30 min of H$_2$O$_2$ treatment. (omitted)

• Advances in environmental research
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• v.3 no.3
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• pp.185-197
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• 2014

Efficient defluorination of perfluorooctanoic acid (PFOA) was achieved by integrating UV irradiation and $Fe^{2+}$ activation of persulfate ($S_2O{_8}^{2-}$). It was found that the UV-$Fe^{2+}$, $Fe^{2+}-S_2O{_8}^{2-}$, and UV-$S_2O{_8}^{2-}$ processes caused defluorination efficiency of 6.4%, 1.6% and 23.2% for PFOA at pH 5.0 within 5 h, respectively, but a combined system of UV-$Fe^{2+}-S_2O{_8}^{2-}$ dramatically promoted the defluorination efficiency up to 63.3%. The beneficial synergistic behavior between $Fe^{2+}-S_2O{_8}^{2-}$ and UV-$S_2O{_8}^{2-}$ was demonstrated to be dependent on $Fe^{2+}$ dosage, initial $S_2O{_8}^{2-}$ concentration, and solution pH. The decomposition of PFOA resulted in generation of shorter-chain perfluorinated carboxylic acids (PFCAs), formic acid and fluoride ions. The generated PFCAs intermediates could be further defluorinated by adding supplementary $Fe^{2+}$ and, $S_2O{_8}^{2-}$ and re-adjusting solution pH in later reaction stage. The much enhanced PFOA defluorination in the UV-$Fe^{2+}-S_2O{_8}^{2-}$ system was attributed to the fact that the simultaneous employment of UV light and $Fe^{2+}$ not only greatly enhanced the activation of $S_2O{_8}^{2-}$ to form strong oxidizing sulfate radicals ($SO{_4}^{\cdot-}$), but also provided an additional decarboxylation pathway caused by electron transfer from PFOA to in situ generated $Fe^{3+}$.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.166-172
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• 2004

The activated carbon was produced from Sancheong bamboo by steam and carbon dioxide gas activation methods. The carbonization of raw material was conducted at 90$0^{\circ}C$ and gas activation reactions were conducted with respect to various conditions. -activation temperature 750-90$0^{\circ}C$, the flow rate of steam 0.5-2g-$H_2O$/g-char$.$hr, the flow rate of carbon dioxide 5-30$m\ell$-$CO_2$/g-char-min and activation time 1-5 hr. The prepared activated carbons were measured yield, the adsorption capacity of iodine and methylene blue, BET specific surface area and pore size distribution. The adsorption capacity of iodine (680.5-1526.1 mg/g) and methylene blue (18.3-221.5 mg/g) increased with creasing activation temperature and activation time. The adsorption capacity of iodine and methylene blue increased with the activation gas quantity in the range of 0.5-1.5g-$H_2O$/g-charㆍhr, 5-18.9$m\ell$-Co$_2$/g-charㆍmin. But those decreased over those range due to the pore shrinkage. The steam activation method was superior in efficiency to carbon dioxide activation method.

• The Journal of Korean Medicine
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• v.21 no.4
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• pp.193-203
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• 2000

Objectives : Hindered barrier function of vascular endothelium has been implicated in the initiation and progression of degenerative vascular diseases such as atherosclerosis. In this study, the effect of Sunghyangchungisan(SHCS) as a protectant against oxidant-induced destruction of endothelial barrier function was assessed. Methods : Toward this end, endothelial cells derived from the human umbilical vein were cultured as monolayers on permeable membrane filters. Endothelial permeability was monitored by measuring transendothelial electrical resistance and movement of low density lipoprotein (LDL) across the endothelial monolayer. Results : Along with increased movement of LDL, $H_2O_2$-induced increase in endothelial permeability was paralleled by a decrease in transendotheliaI electrical resistance. The effect of $H_2O_2$ was mimicked by phorbol 12-myristate 13-acetate (PMA), a potent activator of proteinkinase C. Calphostin-C, a protein kinase C inhibitor, effectively blocked the increase in endothelial permeability induced by $H_2O_2$ or PMA, indicating that activation of protein kinase C is associated with the $H_2O_2-induced$ permeability change. SHCS effectively protected the endothelial monolayer against $H_2O_2-induced$ increase in permeability, whereas, it did not affect PMA-induced change. Forskolin, a potent activator of adenylyl cyclase, antagonized $H_2O_2$ to increase endothelial permeability. In addition, in ${H_2O_2}-treated$ cens, intracenular cAMP concentration was significantly decreased, indicating that impaired cAMP production as well as activation of proteinkinase C is a mechanism underlying ${H_2O_2}>-induced$$H_2O_2$ with regard to its effect on intracellular cAMP content. However, SHCS itself did not affect resting cAMP concentration in endothelial cells. Conclusions : These results suggest that SHCS might operate as an effective protectant against oxidant-induced destruction of endothelial barrier function. The mechanism does not appear to involve direct interaction with protein kinase C- or cAMP-associated signaling mechanism.

• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.113-124
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• 1993

Thermogravimetric analysis of copolymer of acrylonitrile(95%) and methyl acrylate(5%) have been carried out to investigate the activation under $H_2O$(30%) -$N_2$atmosphere at various heating rates. The kinetic equation [$f=1-\exp(-a{\Delta}T)^b$] which was derived on the basis of the nonisothermal activation process of carbon fiber in the $H_2O$(30%)-$N_2$system showed good agreement with experimetal results. The pore volume upon conversion was in good agreement with the model of theoretical pore volume. The pore structures of the activated carbon fiber were influenced by the heating rate, activation temperature and internal-external conversions.

• Environmental Engineering Research
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• v.23 no.3
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• pp.339-344
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• 2018

The Cu loading of a cubic $Ce_{0.8}Zr_{0.2}O_2$-supported Cu catalyst was optimized for a single-stage water gas shift (WGS) reaction. The catalyst was prepared by a co-precipitation method, and the WGS reaction was performed at a gas hourly space velocity of $150,494h^{-1}$. The results revealed that an 80 wt% $Cu-Ce_{0.8}Zr_{0.2}O_2$ catalyst exhibits excellent catalytic performance and 100% $CO_2$ selectivity ($X_{CO}=27%$ at $240^{\circ}C$ for 100 h). The high activity of 80 wt% $Cu-Ce_{0.8}Zr_{0.2}O_2$ catalyst is attributed to the presence of abundant surface Cu atoms and the low activation energy of the resultant process.

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.193-198
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• 1982

The vaporization of $MgFe_2O_4$ was studied in $H_2-CO_2$ atmosphere over the temperature range of 600 to 90$0^{\circ}C$ by means of the transpiration method. It was found that the rate of vaporization for $MgFe_2O_4$ is controlled by a first order phase-boundary chemical reaction. The obtained activation energy of vaporization is 17.1 Kcal/mol.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.7
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• pp.4095-4099
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• 2013

Oxidative stress induces apoptosis in many cellular systems including glioblastoma cells, with caspase-8 activation was regarded as a major contribution to $H_2O_2$-induced cell death. This study focused on the role of the autophagic protein p62 in $H_2O_2$-induced apoptosis in U87MG cells. Oxidative stress was applied with $H_2O_2$, and cell apoptosis and viability were measured with use of caspase inhibitors or autophagic mediators or siRNA p62, GFP-p62 and GFP-p62-UBA (del) transfection. We found that $H_2O_2$-induced U87MG cell death was correlated with caspase-8. To understand the role of p62 in MG132-induced cell death, the levels of p62/SQSTM1 or autophagy in U87MG cells were modulated with biochemical or genetic methods. The results showed that the over-expression of wild type p62/SQSTM1 significantly reduced $H_2O_2$ induced cell death, but knockdown of p62 aggravated the process. In addition, inhibition of autophagy promoted p62 and active caspase-8 increasing $H_2O_2$-induced apoptosis while induction of autophagy manifested the opposite effect. We further demonstrated that the function of p62/SQSTM1 required its C-terminus UBA domain to attenuate $H_2O_2$ cytotoxity by inhibition of caspase-8 activity. Our results indicated that p62/SQSTM1 was a potential contributor to mediate caspase-8 activation by autophagy in oxidative stress process.