• Journal of Energy Engineering
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• v.19 no.2
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• pp.121-127
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• 2010

In present work, sulfonated poly(arylene biphenyklsulfone ether) copolymers containing hydroquinone moiety were successfully synthesized using 4,4'-bis[(4-chlorophenyl)sulfonyl]-1,1'-biphenyl(BCPSBP), hydroquinone sulfonic acid potassium salt(sHQ), 4,4'-sulfonyldiphenol and evaluated their characteristics. Three kinds of polymer electrolyte membranes, PBPSEH-HQ00, PBPSEH-HQ10 and PBPSEH-HQ30 were prepared by using mole fraction of sulfonated hydroquinone(sHQ). The structure of the fabricated polymers was analyzed using NMR, IR and GPC. The Mw(weight-average molecular weights) of the polymers were in the range of 62,000-213,000 g $mol^{-1}$, and the molecular weight distribution (Mw/Mn) varied from 1.66-4.04. The thermal analysis of the copolymers was carried out by TGA and DSC. The temperature of Td5% and Td10% was decreased with the mole fraction of sHQ but Tg was increased with the mole fraction. The water uptake, IEC and ion conductivity were increased with increasing the ionic cluster of the polymers. The proton conductivity equal to 9.4 mS $cm^{-1}$ was measured for the PBPSEH-HQ30 membrane at $90^{\circ}C$ and 100% relative humidity. From the observed results it is clear that the prepared hydrocarbon membrane can be considered as suitable polymer electrolyte membrane for the application of PEMFC.

• Journal of Environmental Science International
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• v.11 no.11
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• pp.1157-1163
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• 2002

The effective removal of microcystins by chlorination was investigated on a laboratory scale. With an initial chl.a concentration of more than 1,000 $\mu\textrm{g}$/ℓ, the required chlorine dose for the effective removal of microcystins from the raw water was more than 8.0 mg/ℓ. Whereas, a chlorine dose of 3.0 mg/ℓcould effectively remove microcystins from raw water containing a chl.a concentration of less than 1,000 $\mu\textrm{g}$/ℓ. The microcystin removal was more effective below pH 8.0, plus the optimum pH range was unrelated to the concentration of toxic algal material. Although chlorination is one of the most effective methods for reducing the toxin from blue-green algae, it causes cell lysis and toxin release. However, it was demonstrated that the released cell lysates and toxins could be effectively removed by a higher dose of the oxidant. The highest removal efficiency of dissolved microcystins(initial concentration: 280 $\mu\textrm{g}$ L$\^$-1/) was with a chlorine dose of 5.0 mg/ℓ.

• Bulletin of the Korean Chemical Society
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• v.29 no.7
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• pp.1327-1331
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• 2008

Novel $CO_2$-soluble 8-hydroxyquinoline (8-HQ) chelating agents were synthesized and evaluated for solubility and metal ion extraction ability in supercritical $CO_2\;(Sc-CO_2)$. Among them, secondary amide-containing 8- HQ derivatives cannot be dispersed well into Sc-$CO_2$, but tertiary amide-containing derivatives can dissolve completely in Sc-$CO_2$ even at low CO2 pressures, perhaps owing to the predominant intermolecular interaction between the chelating agent and the $CO_2$ molecule. Based on 8-HQ chelating agent solubility data, we investigated the extraction of metal ions ($Co^{2+}$, $Cu^{2+}$, $Sr^{2+}$, $Cd^{2+}$, and $Zn^{2+}$) using two highly $CO_2$-soluble 8-HQ derivatives (4d, 4e) in Sc-$CO_2$. The extraction efficiency of tertiary amide-containing 8-HQ ligands, both fluorinated and non-fluorinated forms, was dramatically increased in the presence of diethyl amine (organic base). We suggest that diethyl amine could play an important synergistic role in the stronger metal binding ability of 8-HQ through an in situ deprotonation reaction in Sc-$CO_2$ medium.

• International Commerce and Information Review
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• v.15 no.1
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• pp.117-134
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• 2013

This study examines the moderating effect of HQ-subsidiary cooperation on the relationships between standardization and on-time completion of new product development (NPD) and international new product rollout (INPR). It was empirically tested by a Korean sample to verify the validity of the research framework. The results show that the higher the HQ-subsidiary/agent cooperation, the stronger the effect of NPD timeliness on INPR timeliness. However, HQ-subsidiary cooperation does not moderate the relationship between standardization and INPR timeliness. Under conditions in which the subsidiary and headquarters have a positive relationship, open communications, and regular interactions, more successful new product development in terms of planned time schedule is strongly associated with a much faster introduction to overseas markets.

• Journal of Environmental Health Sciences
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• v.44 no.2
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• pp.196-203
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• 2018

Objectives: The purpose of this study was to assess environmental risk on the emerging contaminants of concern, such as ivermetin, parziquantel, tamiflu and triclosan. Furthermore, we tried to provide a more efficient management practice and a basis for future studies of risk assessment on those substances. Methods: Predicted no effect concentration (PNEC) and predicted environmental concentration (PEC) were determined through modeling and literature reviews. Environmental risk assessment was evaluated by calculating HQ (hazard quotient) by a comparison of PEC (or measured environmental concentration (MEC)) and PNEC. Results: HQ value of tamiflu calculated from MEC was 1.9E-03. For ivermectin and triclosan, the HQ values were not available because these were not detected in the aquatic environment. The toxicity of ivermectin and triclosan showed a very low value, indicating a high level of HQ. However, praziquantel can be categorized into the material that do not require management since they have less than HQ 1. Conclusion: Based on the results of the initial risk assessment, it is assumed that the ivermectin and triclosan have potential to cause direct adverse effects on the aquatic environment. To conduct an accurate environmental risk assessment, the further study on PEC estimation of such contaminants should be actively carried out.

• Journal of Life Science
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• v.19 no.3
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• pp.373-377
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• 2009

Poliovirus, coxsackievirus, and ecovirus isolates from environmental sources were compared with laboratory strains to determine their removal rate in the water treatment process. The recovery efficiencies of poliovirus, coxsackievirus and echovirus using positive strains ranged from $72{\sim}108%$. Regarding virus removal efficiency in water treatment of pilot-plants, about 99% of all of the viruses were removed in the sedimentation step and 100% of viruses were clearly removed through post-ozonation and BAC filteration. Using six cell lines tested viral sensitivity in cell line and showed different sensitivity as viruses. Polioviruses showed higher sensitivity in the BGMK cell line than other cells, and coxsackieviruses were detected in higher level in the BGMK and Vero cell lines. On the other hand, the RD cell line was useful in the isolation of ecoviruses.

• Journal of Life Science
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• v.22 no.9
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• pp.1237-1242
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• 2012

The use of biological-activated carbon (BAC) processes in water treatment involves biofiltration, which maximizes the bacteria's capabilities to remove organic matter. In this study, the distribution of the bacterial community was assessed in response to different types of BAC processes applied downstream in the Nakdong River. The bacterial biomass and activity were $1.20{\sim}34.0{\times}10^7$ CFU/g and 0.61~1.10 mg-C/$m^3{\cdot}hr$ in coal-based BAC, respectively. The attachment of the bacterial biomass and the removal efficiency of the organic carbon were greatest with the coal-based activated carbon. The bacteria attached to each activated carbon material were detected in the order of Pseudomonas genus, Chryseomonas genus, Flavobacterium genus, Alcaligenes genus, Acinetobacter genus, and Spingomona genus. Pseudomonas cepacia was the dominant species in the coal-based materials, and Chryseomonas luteola was the dominant species in the wood-based material.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.833-837
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• 2004

DeniLite$^{TM}$ laccase immobilized platinum electrode was used for amperometric detection of hydroquinone (HQ) and homogentisic acid (HGA) by means of substrate recycling. In case of HQ, the obtained sensitivity is 280 nA/ ${\mu}$M with linear range of 0.2-35 ${\mu}$M ($r^2$ = 0.998) and detection limit (S/N = 3) of 50 nM. This high sensitivity can be attributed to chemical amplification due to the cycling of the substrate caused by enzymatic oxidation and following electrochemical regeneration. In case of HGA, the obtained sensitivity is 53 nA/ ${\mu}$M with linear range of 1-50 $[\mu}M\;(r^2$ = 0.999) and detection limit of 0.3 ${\mu}$M. The response times ($t_{90%}$) are about 2 seconds for the two substrates and the long-term stability is 60 days for HQ and around 40-50 days for HGA with retaining 80% of initial activities. The very fast response and the durable long-term stability are the principal advantages of this sensor. pH studies show that optimal pH of the sensor for HQ is 6.0 and that for HGA is 4.5-5.0. This shift of optimal pH towards acidic range for HGA can be attributed to the balance between enzyme activity and accessibility of the substrate to the active site of the enzyme.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.3
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• pp.199-204
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• 2016

The objective of this study was to determine the effect of nitrification inhibitor dicyandiamide (DCD) and urease inhibitor hydroquinone (HQ) on ammonia ($NH_3$) and nitrous oxide ($N_2O$) emission from pig slurry applied to Timothy (Phleum pretense L.) sward. The daily emission of ammonia ($NH_3$) and nitrous oxide ($N_2O$) was monitored for 9 days in three different treatments; 1) control (only pig slurry application), 2) DCD treatment (pig slurry + DCD), and 3) HQ treatment (pig slurry + HQ). Most $NH_3$ emission occurred after 4~5 days in three treatments. Total $NH_3$ emission, expressed as a cumulative amount throughout the measurement time, was $1.33kg\;N\;ha^{-1}$ in the control. The DCD and HQ treatment decreased total $NH_3$ emission by 16.3% and 25.1%, respectively, compared to the control. Total $N_2O$ emission in the control was $47.1g\;N\;ha^{-1}$. The DCD and HQ treatment resulted in a reduction of 67.9% and 41.8% in total $N_2O$ emission, respectively, compared to the control. The present study clearly indicated that nitrification and urease inhibitor exhibited positive roles in reducing N losses through $NH_3$ and $N_2O$ emission.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2771-2775
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• 2011

Poly-ethylenedioxypyrrole (PEDOP) coated thiolated multiwall carbon nanotubes palladium nanoparticles (MWCNTs-Pd) modified glassy carbon electrode (GCE) [PEDOP/MWCNTs-Pd/GCE] for the determination of hydroquinone (HQ) and it’s isomer catechol (CA) were synthesized and compared with bare GCE and thiolated multiwall carbon nanotubes (MWCNTs-SH/GCE). The modification could be made by simple processes on a GCE with MWCNTs-Pd covered by PEDOP in a 0.05 M tetrabutylammonium perchlorate (TBAP)/MeCN solution system. A well-defined peak potential evaluation of the oxidation of hydroquinone to quinone at 0.05 V (vs. Ag/AgCl), and electrochemical reduction back to hydroquinone were found by cyclic voltammetry (CV) in phosphate buffered saline (PBS) at pH 7.4. Peak current values increased linearly with increasing hydroquinone contents. The peak separation between the anodic and cathodic peaks at the PEDOP/MWCNTs-Pd/GCE was ${\Delta}Ep$ = 40 mV for HQ and ${\Delta}Ep$ = 70 mV for CA, resulting in a higher electron transfer rate. Moreover, good reproducibility, excellent storage stability, a wide linear range (0.1 ${\mu}M$ - 5 mM for HQ and 0.01 ${\mu}M$ - 6 mM for CA), and low detection limits ($2.9{\times}10^{-8}$ M for HQ and $2.6{\times}10^{-8}$ M for CA; S/N = 3) were determined using differential pulse voltammetry (DPV) and amperometric responses; this makes it a promising candidate as a sensor for determination of HQ and CA.