• Polymer(Korea)
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• v.34 no.1
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• pp.20-24
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• 2010

In this study, ETFE-g-PSSA membranes with various degrees of grafting (DOG) and thicknesses were prepared by a simultaneous irradiation method. SEM-EDX instrument was applied to measure the relative distribution of sulfur which is corresponding to that of a grafted polymer over the Cross-section of the ETFE-g-PSSA membranes prepared at various irradiation conditions. The results indicate that to obtain the evenly-grafted membranes, a styrene/dichloromethane ratio is needed to be under 60 (v/v%), and a higher DOG is required as the film thickness increases. The effects of DOG and thickness on the ion exchanging capacity (IEC) and water uptake (WU) were investigated by measuring the IEC and WU values of the membranes with various DOG and thicknesses.

• Membrane Journal
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• v.18 no.3
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• pp.234-240
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• 2008

This work demonstrates the preparation of proton conducting crosslinked polymer electrolyte membranes by blending polystrene-b-poly(hydroxyethyl acrylate) (PS-b-PHEA) and poly(vinyl alcohol) (PVA) at 1 : 1 wt ratio. The PHEA block of the diblock copolymer was crosslinked with PVA using sulfosuccinic acid (SA) via the esterification reaction between -OH of membrane and -COOH of SA, as confirmed by FT-IR spectroscopy. Ion exchange capacity (IEC) continuously increased from 0.14 to 0.91 meq/g with increasing concentrations of SA, due to the increasing portion of charged groups in the membrane. In contrast, the water uptake increased up to 20.0 wt% of SA concentration above which it decreased monotonically. The membrane also exhibited a maximum proton conductivity of 0.024 S/cm at 20.0 wt% of SA concentration. The maximum behavior of water uptake and proton conductivity is considered to be due to competitive effect between the increase of ionic sites and the crosslinking reaction according to the SA concentration.

• Proceedings of the Ginseng society Conference
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• 1984.09a
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• pp.191-197
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• 1984

A further purified fraction (D-O-ANa) was obtained from DPG 3-2 fraction of Ginseng Radix by complete removal of saponins, nucleosides, nucleic acid bases, amino acids, and sugars. D-O-ANa - induced insulin release was investigated to compare with that of DPG 3-2 and other isolated components. Among the sub fractions of DPG 3-2, D-O-ANa exhibited the most potent release of insulin with or without high concentrations of glucose, and it particularly enhanced the second phase of glucose-induced insulin release. DGP 3-2 potentiated significantly the glucose-induced insulin release from the isolated islets of diabetic mice at increasing concentrations of extracellular calcium ions (0.16 - 2.5 mM). A definite relationship was found between calcium $(^{45}Ca)$ uptake and insulin release. Ginsenoside $(G)-Rb_1\;and\;G-Rg_1$ did not enhance the glucose-induced insulin release. The effect of ginseng saponins was blocked by glucose (16.7 mM), being distinctly different from the glucose-potentiated effect of DPG 3-2. The insulin release effect of $G-Rg_1$ was unaffected by the presence or absence of extracellular $Ca^{2+}$ and theophylline. Adenosine also increased insulin release from isolated islets, but had no effect on perfused rat pancreas. Arginine stimulated insulin release less evidently than D-O-ANa, though arginineand adenosine-induced glucagon releases were more remarkable. In conclusion, D-O-ANa appears to be a major fraction in insulin release activity of ginseng and its mode of action may be related to $Ca^{2+}$ ion uptake. This physiological mechanism was distinct from that of the abnormal release induced by ginseng saponins.

• Membrane Journal
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• v.17 no.4
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• pp.311-317
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• 2007

Proton conducting crosslinked membranes have been prepared by polymer blending, which consist of poly(vinyl alcohol-co-ethylene) (PVA-co-PE) and poly(styrene sulfonic acid-co-maleic acid) (PSSA-co-PMA) at 50 : 50 wt ratio. Two kinds of PSSA-co-PMA copolymer with 3 : 1 and 1 : 1 the molar ratio of PSSA to PMA wereused as a proton conducting source. The ethylene content of PVA-co-PE was also changed as 0, 27 and 44 mol%. The membranes were thermally crosslinked via the esterification reaction between -OH of PVA and -COOH of PMA, as demonstrated by FT-IR spectroscopy (PVA-co-PE)/(PSSA-co-PMA) membranes with 3 : 1 the molar ratio of PSSA to PMA showed higher ion exchange capacity (IEC), lower water uptake and higher proton conductivity than those with 1 : 1 molar ratio. As the PE concentration increased, the IEC values, water uptake and proton conductivities decreased continuously. These properties were elucidated in terms of competitive effect between the concentration of sulfonic acid, hydrophilicity and the crosslinked structure of membranes.

• Clean Technology
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• v.30 no.2
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• pp.123-133
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• 2024

Zeolite template carbon (ZTC) was synthesized as an adsorbent to remove low-concentration CH₄ from the atmosphere. The synthesis of ZTC was performed using CH₄ and C₂H₂ as carbon precursors and their impact on adsorption was investigated. ZTC was also synthesized using Y zeolite ion-exchanged with CaCl₂ and LiCl as templates to investigate the effect of using metals in ion exchange. The comparison of the carbon precursors revealed that C₂H₂ had a higher carbon yield than CH₄. The synthesized ZTC exhibited developed micropores due to carbon deposition deep inside the micropores of the zeolite template. The kinetic diameter of C₂H₂ (0.33 nm) is smaller than that of CH₄ (0.38 nm), which allowed for its deposition. The study compared metal precursors used for ion exchange and confirmed that the CaCl₂-based ZTC developed more micropores compared to the LiCl-based ZTC. The ion-exchanged Ca inhibited pore blocking by the carbon precursor, allowing it to enter the pores. The ability of synthesized ZTC to adsorb N₂ and CH₄ at 298 K was investigated. The results showed that CH₄ had a higher overall adsorption amount than N₂. The sample synthesized using C₂H₂ and CaY exhibited the highest N₂ and CH₄ adsorption capacity. However, the sample synthesized with CH₄ had the highest CH₄/N₂ gas uptake ratio, which is a crucial factor in designing an adsorption process. The observed difference was likely caused by the underdevelopment of ultrafine pores that are associated with N₂ adsorption. This resulted in a reduction of N₂ adsorption, leading to an increase in CH₄/N₂ separation.

• Korean Journal of Veterinary Research
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• v.36 no.2
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• pp.327-335
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• 1996

Recently in spite of the interest on the regulation of intracellular $Mg^{2+}$ by neurotransmitters or drugs, the magnesium ion($Mg^{2+}$) regulation by ${\alpha}_1$-adrenoceptor stimulation has not been studied in the heart yet. To elucidate the regulation of ${\alpha}_1$-adrenoceptor stimulation-induced $Mg^{2+}$ release and the effects of ${\alpha}_1$-adrenoceptor stimulation on pathophysiological conditions, in this study we have evaluated the effects of phenylephrine, PMA, $H_7$. staurosporine, verapamil and lidocaine on $Mg^{2+}$ release in perfused guinea pig heart. During preperfusion exogenous $Mg^{2+}$ was added to the medium to give 1.2mM 15min before starting to addition of drugs, and then the infusion of exogenous $Mg^{2+}$ was stopped. $Mg^{2+}$ in the perfusate leaving the heart was measured by atomic absorption spectrophotometry. $Mg^{2+}$ free solution produced an increase in heart rate and phenylephrine elicited $Mg^{2+}$ release from the heart. $Mg^{2+}$ release by phenylephrine was abolished by combined treatment with prazosin. By contrast, cardiac $Mg^{2+}$ uptake induced by a protein kinase C(PKC) activator, PMA was abolished by a selective PKC inhibitor, staurosporine. And the phenylephrine-induced $Mg^{2+}$ release was not affected by the PKC inhibitor, $H_7$. When verapamil or lidocaine was added to perfusing solution, $Mg^{2+}$ release was potentiated by phenylephrine from perfused guinea pig heart. These results suggest that ${\alpha}_1$-adrenoceptor stimulation caused $Mg^{2+}$ release and that PKC is not involved in ${\alpha}_1$-adrenoceptor mediated $Mg^{2+}$ release from perfused guinea pig heart. Under pathophysiological conditions, the $Mg^{2+}$ alteration by ${\alpha}_1$-adrenoceptor stimulation is considerable.

• Journal of the Mineralogical Society of Korea
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• v.15 no.4
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• pp.315-327
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• 2002

Al-pillared clay was synthesized by constructing pillars of aluminum oxides at the interlayer of montmorillonite in bentonite. XRD, DTA and chemical analyses of Al-pillared clay were performed to examine mineralogical properties. Batch adsorption experiments were also conducted to determine the adsorption properties of this synthesized clay for phosphate ions. XRD analyses showed that the interlayer space of Al-pillared clay expanded to 18.03 $\AA$ at room temperature and shifted to $17 \AA$ after heating to $550^{\circ}C$. A small change in interlayer space after heating indicates high thermal stability. The interlayer expansion by glycerol was also very small. From DTA analyses, pillared clay showed the characteristic endothermic peaks at 270 and $420^{\circ}C$ , which might be caused by dehydration in framework of pillars between interlayers. Adsorption experiment revealed that Al-pillared clay had an excellent adsorption capacity to the phosphate ions, whereas montmorillonite had very low adsorption capacity to phosphate ions. In phosphate solution concentration up to 300 mg/L, 2 g of pillared clay could uptake almost 100% of phosphate ions from 20 mL of solution. After heat treatment of the phosphate adsorbed pillared clay at 50$0^{\circ}C$ to remove phosphate, the calcined pillared clay could adsorb phosphate ions with a little decreased adsorption efficiency. This fact indicates that Al-pillared clay can be recycled for the adsorption of phosphate ions.

• 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 the Korean Electrochemical Society
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• v.19 no.1
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• pp.21-27
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• 2016

Vanadium redox flow batteries (VRFBs) using the electrolytes containing various vanadium ions in sulfuric acid as supporting solution are one of the energy storage devices in alternatively charging and discharging operation modes. The positive electrolyte contains $V^{5+}/V^{4+}$ and the negative electrolyte $V^{2+}/V^{3+}$ depending on the operation mode. To prevent the mixing of two solutions, proton exchange membranes are mainly used in VRFBs. Nafion 117 could be the most promising candidate due to the strong oxidative property of $V^{5+}$ ion, but causes high crossover of electroactive species to result in a decrease in coulombic efficiency. In this study, the composite membranes using Nafion ionomer and porous polyethylene substrate were prepared to keep good chemical stability and to decrease the cost of membranes, and were compared to the properties and performance of the commercially available electrolyte membrane, Nafion 117. As a result, the water uptake and ionic conductivity of the composite membranes increased as the thickness of the composite membranes increased, but those of Nafion 117 slightly decreased. The permeability of vanadium ions for the composite membranes significantly decreased compared to that for Nafion 117. In a single cell test for the composite membranes, the voltage efficiency decreased and the coulombic efficiency increased, finally resulting in the similar energy efficiency. In conclusion, the less cost of the composite membranes by decreasing 6.4 wt.% of the amount of perfluorinated sulfonic acid polymer due to the introduction of porous substrate and lower vanadium ion permeability to decrease self-discharge were achieved than Nafion 117.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.133-139
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• 2017

This study investigated the effects of NaCl and jasmonic acid (JA) on the growth and physiological responses of spearmint (Mentha spicata L.). Spearmint was hydroponically grown for 3 weeks in modified Hoagland solution containing 0 (untreated control), JA ($20{\mu}M$ JA pretreatment), NaCl (50 mM NaCl treatment) and JA + NaCl ($20{\mu}M$ JA pretreatment + 50 mM NaCl treatment). Growth characteristics, chlorophyll, vitamin C, proline contents, DPPH scavenging activity and inorganic ion contents were evaluated. As a results, there were significant decreases in the plant height, leaf length, leaf width, and fresh weight of plants, treated with NaCl compared with control. On the other hand, the dry matters of shoot and root treated with JA + NaCl combination were better than control or NaCl treatment. Chlorophyll a and b contents in JA treatment was the highest. Vitamin C, antioxidant activity, and proline content in shoot were increased in NaCl treatment which showed low level of growth rate. The K/Na ratio, which is known to indirectly reflect the balance of ion uptake, was higher in a single treatment of JA than the control group, while lower in salt treatment (NaCl and JA + NaCl) because of high $Na^+$ absorption. In conclusion, these results showed that moderate stress treatment such as low level salt treatment and plant growth regulator jasmonic acid (JA) application would be potential strategies to improve the quality of spearmint by inducing the accumulation of secondary metabolites containing high antioxidant activity and essential oil.