• Preventive Nutrition and Food Science
• /
• v.20 no.1
• /
• pp.22-28
• /
• 2015

Phenolic rich ethyl acetate fraction (EAF) from lotus leaves was prepared and its bioactive components, antioxidant and cytoprotective effects were investigated. EAF showed high total phenolic content and flavonoid content and contained rutin ($11,331.3{\pm}4.5mg/100g\;EAF$), catechin ($10,853.8{\pm}5.8mg/100g\;EAF$), sinapic acid ($1,961.3{\pm}5.6mg/100g\;EAF$), chlorogenic acid ($631.9{\pm}2.3mg/100g\;EAF$), syringic acid ($512.3{\pm}2.5mg/100g\;EAF$), and quercetin ($415.0{\pm}2.1mg/100g\;EAF$). EAF exerted the $IC_{50}$ of $4.46{\mu}g/mL$ and $5.35{\mu}g/mL$ toward DPPH and ABTS cation radicals, respectively, and showed strong reducing power, which was better than that of ascorbic acid, a positive control. Additionally, EAF protected hydroxyl radical-induced DNA damage indicated by the conversion of supercoiled pBR322 plasmid DNA to the open circular form and inhibited lipid peroxidation of polyunsaturated fatty acid in a linoleic acid emulsion. In cultured hepatocytes, EAF exerted a cytoprotective effect against oxidative stress by inhibiting intracellular reactive oxygen species formation and membrane lipid peroxidation. In addition, depletion of glutathione under oxidative stress was remarkably restored by treatment with EAF. The results suggest that EAF have great potential to be used against oxidative stress-induced health conditions.

• Proceedings of the IEEK Conference
• /
• 2001.10a
• /
• pp.106-110
• /
• 2001

Formation of stoichiometric lithium-, nickel-, and zinc- ferrites by calcining organo-metallic precursors a temperature below 40$0^{\circ}C$ is examined using DTA/TG, and XRD techniques. It attempts to simulate th immobilization of metal ions in industrial liquid influents (waste) through the synthesis of stoichiometric spinel ferrites (SSF). Two steps of the SSF formation during thermal treatments are noted. The transformation of magnetite to ${\gamma}$ - Fe$_2$O$_3$and subsequent first formation of SSF were observed at temperatures ranging from 200 to 45$0^{\circ}C$. Th formation of cation-containing ${\gamma}$-Fe$_2$O$_3$and subsequent second formation of the ferrite occurred at temperature ranges of < 45$0^{\circ}C$ and 500 to $650^{\circ}C$, depending on the heating rate used. Then the temperature range of 200t 45$0^{\circ}C$ is critical to the performance of the technique, because a calcination at the range would lead to a complete formation of SSF, avoiding the occurrences of ${\gamma}$-Fe$_2$O$_3$and ion-containing ${\gamma}$-Fe$_2$O$_3$. If not, so $\alpha$-Fe$_2$O$_3$would occur. And annealing at temperature above $650^{\circ}C$ must be employed by which solid-state reactio of $\alpha$-Fe$_2$O$_3$with metal ions (possibly metal oxides) to form SSF can be conducted.

• Journal of the Korean Chemical Society
• /
• v.36 no.5
• /
• pp.692-696
• /
• 1992

$NH_4^+ form cation exchange resin was used to separate one rare earth element from the rare earth mixture solution using Ln-EDTA eluent. Rare earth mixture solution was passed through the resin bed and eluted with 0.1M La-EDTA solution as an eluent. In here all the rare earth element except lanthanum ion are eluted and lanthanum ion absorbed in resin bed is eluted using 0.1M EDTA solution. If Ce-EDTA solution instead of La-EDTA solution was used as an eluent, all the rare earth element except cerium ion are eluted and cerium ion is eluted with 0.1M EDTA solution. This method can be applied to separate the individual rare earth element from the mixture. The separation mechanism is as follows: Absorption : 3RNH_4 ＋ Ln^{3+} = R_3Ln ＋ 3NH_4^+, La-EDTA elution : R_3Ln ＋ La-Y- = R_3La ＋ Ln-Y-, EDTA elution : R_3La ＋ HY^3- = La_-Y ＋ RH ＋ 2R^-.$

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.8
• /
• pp.873-876
• /
• 2012

Ionic liquids (ILs) existing in the liquid ion form under standard conditions show a unique properties. 1-10-Alkyl-3-methyl-imidazolium bromide ([C10mim][Br]) is one of the ILs that shows amphiphilic characteristics under specific conditions. This property enables it to function as a surfactant, and therefore, it finds applications in a wide range of areas. In this study, we tried to predict the behavior, especially the aggregation aspect, of [C10mim][Br] in an aqueous solution using molecular dynamics (MD) simulations. The canonical (NVT) ensemble was used to relax the system and trace the trajectory of atoms. Several case studies were simulated and the interaction among [C10mim]+, [Br]-, and water was analyzed using the radial distribution function of each atom. The density distribution function was also used for the structural analysis of the entire system. We used the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code for the present MD simulations.

• Archives of Plastic Surgery
• /
• v.35 no.4
• /
• pp.407-412
• /
• 2008

Purpose: Hydrofluoric acid(HF) is one of the most dangerous mineral acids with the dissociated fluoride ions. The initial corrosive burn is caused by free hydrogen ion, and the second and more severe burn is caused by penetration of fluoride ions into subcutaneous tissues. Silver is a cation producing dressing, an effective antimicrobial agent, but older silver-containing formulations are rapidly inactivated by wound environment, requiring frequent replenishment. But, $Acticoat^{(R)}$ is a relatively new form of silver dressing which helps avoid the problems of earlier agents. The aim of this study is to evaluate effects of $Acticoat^{(R)}$, silver-containing dressing on the treatment for HF injury wound. Methods: From september 2006 to september 2007, the study was carried out with 10 patients who had HF partial thickness burns. $Acticoat^{(R)}$ dressing and 10% calcium gluconate wet gauze dressings in 10 cases. As a principle, in the emergency treatment, partial or complete removal of the nail and early bullectomy along with copious washing with normal saline was done, depending on the degree of HF invasion of the wound. Wound was dressed with $Acticoat^{(R)}$ and 10% calcium gluconate solution. The effect of dressing was investgated by serial bacterial culture and wound exudates assessment. Results: We therefore reviewed 10 cases of HF-induced chemical burns and treatment principle. The 10 cases who came to the hospital nearly immediately after the injury healed completely without sequelae. Conclusion: As the industrial sector develops, the use of HF is increasing more and more, leading to increased incidences of HF-induced chemical burns. The education of patients regarding this subject should be empathized accordingly. In conclusion, $Acticoat^{(R)}$ dressing is a better choice for HF partial thickness burn injuries because of shorter healing time, less pain and more comfortable dressing.

• Journal of the Korean Chemical Society
• /
• v.36 no.2
• /
• pp.197-204
• /
• 1992

The cationic polymerization of cyclic acetals are investigated theoretically using the semiempirical MINDO/3, MNDO, and $AM_1$, methods. The nucleophilicity and basicity of cyclic acetals can be explained by the negative charge on oxygen atom of cyclic acetals. The reactivity of propagation in the polymerization of cyclic acetals can be represented by the positive charge on $C_2$ atom and the low LUMO energy of active species of cyclic acetals. The reactivity of 2-buthyl-1,3-dioxepane(2-Bu-DOP) of cyclic oxonium and opening carbenium ion form is expected computational stability of the oxonium ion by 5${\sim}$7kcal/mole favoring the carbenium ion. Owing to the rapid equilibrium of these cation forms and the reaction coordinate based on calculation that the reaction coordinate based on calculation that the chain growth $S_N1$ mechanism will be at least as fast as that for $S_N2$ mechanism.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.12
• /
• pp.2002-2010
• /
• 2006

This study examined the quenching of ofloxacin (OFL) and flumequine (FLU) fluorescence by $Cuj^{2+}$, $Ni^{2+}$, $Co^{2+}$ and $Mn^{2+}$ in an aqueous solution. The change in the fluorescence intensity and lifetime was measured at various temperatures as a function of the quencher concentration. According to the Stern-Volmer plots, the fluorescence emission was quenched by both collisions (dynamic quenching) and complex formation (static quenching) with the same quencher but the effect of static quenching was larger than that of dynamic quenching. Large static and dynamic quenching constants for both OFL and FLU support significant ion-dipole and orbital-orbital interactions between fluorophore and quencher. For both molecules, the static and dynamic quenching constants by $Cu^{2+}$ were the largest among all the metal quenchers examined in this study. In addition, both the static and dynamic quenching mechanisms by $Cu^{2+}$ were somewhat different from the quenching caused by other metals. Between $Ni^{2+}$ and FLU, a different form of chemical interaction was observed compared with the interaction by other metals. The change in the absorption spectra as a result of the addition of a quencher provided information on static quenching. With all these metals, the static quenching constant of FLU was larger than those of OFL. The fluorescence of OFL was quite insensitive to both the dynamic and static quenching compared with FLU. This property of OFL can be explained by the twisted intramolecular charge transfer in the excited state.

• Ceramist
• /
• v.23 no.2
• /
• pp.200-210
• /
• 2020

Supported catalysts are at the heart of manufacturing essential chemical, agricultural and pharmaceutical products. While the longevity of such systems is critically hinged on the durability of metal nanoparticles, the conventional deposition/dispersion techniques are difficult to enhance the stability of the metal nanoparticles due to the lack of control over the interaction between metal-support. Regarding this matter, ex-solution has begun to be recognized as one of the most promising methodologies to develop thermally and chemically robust nanoparticles. By dissolving desired catalysts as a cation form into a parent oxide, fine and uniformly distributed metal nano-catalysts can be subsequently grown in situ under reductive heat treatment, which is referred to ex-solution. Over the several years, ex-solved analog has resulted in tremendous progress in the chemical-electrochemical applications due to the exceptional robustness coupled with ease synthesis. Herein, we describe the ex-solution process in detail which therein introducing the unique characteristics of ex-solved particles that distinguish them from conventionally dispersed nanoparticles. We then go through the history of science regarding the ex-solution phenomena and summarize several major research achievements which embrace the ex-solved nanoparticles to markedly promote the catalytic performances. In conclusion, we address the remaining challenges and the future perspectives of this rapidly growing field.

• Korean journal of food and cookery science
• /
• v.2 no.2
• /
• pp.55-61
• /
• 1986

This study was attempted to investigate the occurrence and the partial characteristics of pectinesterase (PE) in cucumbers. And the involvement of endogenous cucumber PE with the formation of insoluble pectic acid, in the presence of endogenous or added calcium ions, was also studied. The results of this study are as follows: 1) PE activity was detected in whole cucumber homogenate. 2) The optimum pH and temperature of this enzyme were found to be 8.5 and $50^{\circ}C$, respectively 3) When PE extract was added to 0.25% pectin solution, pectin gel was formed. The time required for the formation of pectin gel was reduced when the pectin solution was adjusted to the optimum conditions for PE activity(pH 8.5, $50^{\circ}C$) and $CaCl_2$ was added. 4) Cucumber juice which was heated to $100^{\circ}C$ for 10 minutes fatted to form any insoluble pectate precipitate. The formation of precipitate in cucumber juice was accelerated by preheating to $50^{\circ}C$, adjusting to pH 8.5 and addition of $CaCl_2$. 5) These results can be interpreted that endogenous PE in cucumber juice demethylates pectin, allowing interlinking of pectin molecules via divalent cation $(Ca^{++})$ and thus forming insoluble Ca-pectate. Therefore additional firming effects of cucumber can be expected to be obtained through activation of PE in conjunction with calcium ions.

• Economic and Environmental Geology
• /
• v.21 no.3
• /
• pp.235-255
• /
• 1988

Talc deposit of pipe-like form occurrs in the lower part of the Hyangsanri Dolomite with a strike of N40 -50 E and a dip of 40 -50 NW which is one formation of the Ogcheon Super Croup. The pipi-like ore body plunge at about $40^{\circ}$ to the west and are parallel to the lineation developed in the area. Structural formulae of tales occurred in this deposit are close to the ieal composition $Mg_6Si_8O_{20}(OH)_4$ showing limited deviation from ideal one. Substitution of Al for Si in tetrahedral site is of little or nothing ranging 0-0.04 and octahedral occupancy is close to six ranging 5.88-5.98 atoms per unit cell. Predominant octahedaral cation is Mg and proportion of divalent cations is generally over 97percent. Calcite -dolomite thermometry is obtained by determining the mol % $MgCO_3$using of EPMA and XRD methods. The peak metamorphic temperature can be estimated at $470{\pm}30^{\circ}C$ in the area whereas carbonates occurred at near talc ore show lower temperature than $400^{\circ}C$ that the calcite solvus limit is not well established. It indicates that the talc deposit was formed at the lower temperature that the metamorphic temperature. Cosequently, the formation of talc by metamorphism is questionable and the alteratin zone developed around the talc ore is very limited. The occurrence of talc ore in the dolomite as well as mineralogy, calcite-dolomite geothermometry, chlorite geothermometry, field and microscopic evidence suggest that siliceous ascending hydrothermal solution along the fracture is responsible for the formation of talc. It was considered that the slight fracturing of dolomite was formed by deformation prior to the mineralization.