• Honam Mathematical Journal
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• v.27 no.1
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• pp.51-68
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• 2005

In this paper we solve a generalized Popoviciu functional equation and investigate the stability of this equation.

• Korean Journal of Veterinary Service
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• v.39 no.2
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• pp.81-86
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• 2016

Honeybee venom (BV) from Apis mellifera L. has been used as natural antimicrobial compounds in pigs, cows, dairy cattle and chicken farms in Korea. The purpose of this study was conducted to confirm homogeneity and stability of BV dissolved with distilled water or saline solution. Melittin was analyzed with ultra-high performance liquid chromatography (UPLC) for BV to secure the validation of analysis. BV at concentration of 1 mg/mL was dissolved with distilled water or saline solution at room temperature. Homogeneity of BV dissolved with distilled water or saline solution at upper, milddle, and lower layers all satisfied the accuracy and precision criteria. Stability of BV dissolved with distilled water or saline solution for 7 days all satisfied the criterion both light and dark storage condition. BV has satisfied with homogeneity and stability in distilled water or saline solution at room temperature under light or dark condition. The results of this study suggest that BV has a possibility as the substitute of natural antimicrobial agents for the animal drugs and feed additives.

• YAKHAK HOEJI
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• v.38 no.5
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• pp.488-495
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• 1994

To evaluate the feasibility of transmucosal delivery of leucine enkephalin (Leu-Enk) and its synthetic analog, $[D-Ala^2]$-leucine enkephalinamide (YAGFL), their physicochemical stabilities in aqueous buffered solutions were first investigated using a stability indicating high performance liquid chromatography. The degradation of Leu-Enk and YAGFL followed the pseudo-first-order kinetics. From the pH-rate profiles, it was found that the maximal stability of the two pentapeptides was at the pH of about 5.0. The shelf lives $(t_{90%})$ for the degradation of Leu-Enk and YAGFL at pH 5.0 and $40^{\circ}C$ were found to be 48.13 and 50.9 days, respectively. From the temperature dependence of the degradation, activation energies for Leu-Enk and YAGFL were calculated to be 13.61 and 13.47 kcal/mole, respectively. A higher ionic strength and a higher initial peptide concentration in buffered solution slowed the degradation of the two pentapeptides. The addition of 2-hydroxypropyl-${\beta}$-cyclodextrin into the peptide solution did not affect the stability significantly.

• Journal of the Korean institute of surface engineering
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• v.34 no.4
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• pp.281-288
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• 2001

Phosphating treatments have been performed to improve paint adhesion and corrosion resistance of zinc and zinc alloy coated steels for a long time. In this work, the effects of the addition of chelate compound were studied to improve the stability of surface conditioning solution and properties of zinc phosphate films. The coalescence of colloidal Ti-compound and extraneous charged particles (alkaliearth metal cation such as $Mg^{2+}$ , $Ca^{2+}$ ) were suppressed by using a surface conditioning solution with chelate compound. Therefore, after surface conditioning solution containing chelate compound was left standing for one week at room temperature, the formation of a white sediment was decreased comparing to surface conditioning solution without chelate compound. The crystal size of phosphate film was fine and the whiteness value of phosphated zinc coated steel sheets was also high without the decrease of corrosion resistance and anti-patina. It was very effective to use chelate compound improving the stability of surface conditioning solution.

• Journal of Pharmaceutical Investigation
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• v.23 no.4
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• pp.225-229
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• 1993

The stability of omeprazole in the aqueous solutions containing arginine or sodium phosphate dibasic(SPD) was examined at 30, 40 and $50^{\circ}C$. Arginine or anhydrous SPD was added to omeprazoie solution ($200{\mu}g/\;ml$ in distilled water) to yield $100{\mu}g/\;ml$ concentration of each. Then, the solution was kept at 30, 40 or $50^{\circ}C$ for 90 hrs. Aliquots of the solution were withdrawn at specified time intervals and assayed by HPLC for intact omeprazole. The remaining percentage-time curves revealed that omeprazole was degraded rapidly as funtions of time and temperature following pseudo first-order kinetics. The rate constant in the SPD solution was much higher than in the arginine solution. In other words. the degradation half-lives of omeprazole at $30^{\circ}C$, for example, was 148 and 76 hr in arginine and SPD solutions respectively. The initial pH of the solution containing $100{\mu}g/\;ml$ of arginine or SPD was 9.7 or 8.7, respectively. Since omeprazole is more stable as the pH of its solution becomes more alkaline, the longer half-life of omeprazole in arginine solution could be explained by the more alkaline characteristics of arginine than SPD in the solution. The activation energy necessary for the degradation reaction was almost identical in both solutions, indicating similar degradation mechanisms of omeprazole in the solutions. In conclusion, omprazole was more stable in the presence of arginine than of SPD.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3494-3499
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• 2009

The stability of omeprazole in the aqueous solutions containing loxoprofen or Sodium bicarbonate was examined at room temperature. Loxoprofen or Sodium bicarbonate (60 mg) was added to omeprazole (600 ${\mu}g$/ml) solution to check the stability profile. Then, the solution was kept at room temperature for 80 hours. The concentration was assayed at each concentration by stability-indicating High performance liquid chromatography (HPLC) method. Aliquots of the solution were withdrawn at specified time intervals and assayed by chromatographic analysis for intact omeprazole. The relation between omeprazole concentration and peak area was linear from 5 to 160 ${\mu}g$/ml. The analysis method was precise with relative standard deviation (% RSD) no greater than 3.05 %. The remaining percentage-time curves revealed that omeprazole was degraded rapidly as functions of time and temperature following pseudo first-order kinetics. In conclusion, the stability of omeprazole was significantly affected by liquid solutions mixed with alkalizer (Sodium carbonate) or the NSAIDs (loxoprofen).

• Journal of Pharmaceutical Investigation
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• v.34 no.4
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• pp.269-274
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• 2004

To enhance the solubility and stability of lansoprazole (LAN), new proton pump inhibitor, we were prepared various molar ratio of inclusion complex with $2-hydroxypropyl-{\beta}-cyclodextrin$ (HPCD) and organic alkali agent, meglumine (MEG). Inclusion complex formation of LAN with HPCD was investigated by Differential Scanning Calorimetry and X-ray diffractometry. The aqueous solubilities of inclusion complexes, and the stabilities of 1:4 and 1:5 inclusion complexes in aqueous solutions containing different concentrations of MEG were examined. The stability of 1:5 LAN-HPCD inclusion complex containing MEG, which was equaled to amount of LAN, was performed in 0.9% NaCl and 5% dextrose solution. The formation of inclusion complex of LAN with HPCD was $A_L$ type and the molar ratio of complex was 1:1. The stability constant was $41.557\;M^{-1}$. As molar ratio of LAN to HPCD was increased, solubility of inclusion complex was increased. 1:5 LAN-HPCD inclusion complex was more stable than 1:4 LAN-HPCD inclusion complex. And as contained MEG amount in LAN solution was increased, stability of 1:4 and 1:5 LAN-HPCD inclusion complexes was improved. Also stability of 1:5 LAN-HPCD-MEG inclusion complex in 0.9% NaCl solution and 5% dextrose solution was similar to it in water at room temperature, but it was unstable at $40^{\circ}C$.

• Journal of Pharmaceutical Investigation
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• v.27 no.2
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• pp.139-143
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• 1997

Epidermal growth factor (EGF) is a mitogen which activate the proliferation of basal cells in skin, which implicate the wound healing in severe skin damage such as burn. To carry out the preclinical test for the pharmacological action of EGF, EGF in transdermal delivery system must be stable. Since EGF is a protein susceptible to proteolysis and unstable in aqueous solution, in vitro stabilization of EGF is prerequisite for the formulation. In this study, effect of additives on the stability of EGF is investigated in vitro. The stability of EGF in aqueous solution was enhanced with the various water-soluble polysaccharides such as HPMC, sorbitol, mannitol and dextrin. EGF was successfully extracted from the ointment with 5% HPMC solution, and EGF in aqueous solution and ointment was also successfully stabilized with 5% HPMC. The ointments prepared with different amount of EGF were applied on the damaged dorsal skin of rats for the determination of optimal concentration of EGF. The ointment with EGF $(10\;{\mu}g/g)$ showed good wound healing action on the damaged skin of rats.

• Coupled systems mechanics
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• v.3 no.1
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• pp.1-25
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• 2014

In this work, we present the theoretical formulation, operator split solution procedure and partitioned software development for the coupled thermomechanical systems. We consider the general case with nonlinear evolution for each sub-system (either mechanical or thermal) with dedicated time integration scheme for each sub-system. We provide the condition that guarantees the stability of such an operator split solution procedure for fully nonlinear evolution of coupled thermomechanical system. We show that the proposed solution procedure can accommodate different evolution time-scale for different sub-systems, and allow for different time steps for the corresponding integration scheme. We also show that such an approach is perfectly suitable for parallel computations. Several numerical simulations are presented in order to illustrate very satisfying performance of the proposed solution procedure and confirm the theoretical speed-up of parallel computations, which follow from the adequate choice of the time step for each sub-problem. This work confirms that one can make the most appropriate selection of the time step with respect to the characteristic time-scale, carry out the separate computations for each sub-system, and then enforce the coupling to preserve the stability of the operator split computations. The software development strategy of direct linking the (existing) codes for each sub-system via Component Template Library (CTL) is shown to be perfectly suitable for the proposed approach.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2801-2808
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• 2022

The synergistic effect of ZrC nanoparticle pining and Re solution in W matrix on the thermal stability of tungsten was studied by investigating the evolution of the microstructure, hardness and tensile properties after annealing in a temperature range of 1000-1700 ℃. The results of metallography, electron backscatter diffraction pattern and Vickers micro-hardness indicate that the rolled W-1wt%Re-0.5 wt% ZrC alloy has a higher recrystallization temperature (1600 ℃-1700 ℃) than that of the rolled pure W (1200 ℃), W-0.5 wt%ZrC (1300 ℃), W-0.5 wt%HfC (1400-1500 ℃) and W-K-3wt%Re alloy fabricated by the same technology. The molecular dynamics simulation results indicated that solution Re atoms in W matrix can slow down the self-diffusion of W atoms and form dragging effect to delay the growth of W grain, moreover, the diffusion coefficient decrease with increasing Re content. In addition, the ZrC nanoparticles can pin the grain boundaries and dislocations effectively, preventing the recrystallization. Therefore, synergistic effect of solid solution Re element and dispersed ZrC nanoparticles significantly increase recrystallization temperature.