• Bulletin of the Korean Chemical Society
• /
• v.24 no.5
• /
• pp.566-568
• /
• 2003

The phosphor $CaTiO_3:Pr^{3+}$ attracts much attention as a low-voltage red phosphor because of its good chromaticity and intrinsic conductivity. The addition of Ga into this CaTiO₃:Pr led the luminance intensity to greatly enhance without the change of the wavelength for the electronic transition and the peak shape of it. The increase of the recombination rate of electron-hole pairs through the Ga ion doping, which was expected to play a role of a hole-trap center, is proposed to be one of the reasons for the enhancement of the cathodoluminescence intensity.

• Nuclear Engineering and Technology
• /
• v.31 no.6
• /
• pp.541-547
• /
• 1999

Corrosion control, in the end-shield cooling system of Wolsung Nuclear Power Plant, is directly related to the control of dissolved oxygen (DO). The current method, being used to deoxygenate the end-shield cooling water, is a chemical treatment by addition of reducing agent, hydrazine, to react with DO. This method has several limitations including high reaction temperature of hydrazine , unwanted explosive hydrogen gas production, and its intrinsic harmful property. A new approach to remove DO using a membrane-based oxygen removal system (MORS) was tried to overcome limitations of the hydrazine treatment. The DO removal efficiency of the MORS was found to be in the range 87% to 98%: The higher vacuum, the lower water flow rate and the higher water temperature tend to increase the DO removal efficiency.

• Integrative Medicine Research
• /
• v.6 no.3
• /
• pp.254-259
• /
• 2017

Background: Those classified as Tae-Eum (TE)-type people in Sasang constitutional medicine (SCM) are prone to obesity. Although extensive clinical observations have confirmed this tendency, the underlying physiological mechanisms are unknown. Here, we propose a novel hypothesis using integrative physiology to explain this phenomenon. Methods: Hypoactive lung function in the TE type indicates that respiration is attenuated at the cellular level - specifically, mitochondrial oxygen consumption. Because a functional reduction in cellular energy metabolism is suggestive of intrinsic hypoactivity in the consumption (or production) of metabolic energy, we reasoned that this tendency can readily cause weight gain via an increase in anabolism. Thus, this relationship can be derived from the graph of cellular metabolic power plotted against body weight. We analyzed the clinical data of 548 individuals to test this hypothesis. Results: The statistical analysis revealed that the cellular metabolic rate was lower in TEtype individuals and that their percentage of obesity (body mass index >25) was significantly higher compared to other constitutional groups. Conclusion: Lower cellular metabolic power can be an explanation for the obesity trend in TE type people.

• Journal of Pharmaceutical Investigation
• /
• v.10 no.3
• /
• pp.33-45
• /
• 1980

In order to increase the solubility of metoclopramide, various ratio coprecipitates with polyvinylpyrrolidone (M.W. 40,000) were prepared. The experiments of the solubility, physicochemical characteristics were quantitatively developed. The solubility increased as the ratio of rnetoclopramide to polyvinylpyrrolidone in metoclopramide-polyvinylpyrrolindone coprecipitate increased. In powder state, the dissolution rate of metoclopramide-polyvinylpyrrolidone coprecipitate was greater than that of metoclopramide and metoclopramide-polyvinylpyrrolidone physical mixture. Dissolution characteristics of non-disintegrating disk with constant surfacearea was in accord with Noyes-Nernst equation. The intrinsic dissolution rate, G, at $37^{\circ}C$ was $3.98{\times}10^{-7}M/cm^2{\cdot}min$ for metoclopramide, $2.26{\times}10^{-6}\;M/cm^2{\cdot}min$ for 1 : 5 metoclopramide-polyvinylpyrrolidone coprecipitate, respectively. Accordingly, activation energy of metoclopramide was 15,061cal/M, 9,178cal/M for 1 : 5 metoclopramide-polyvinylpyrrolidone coprecipitate and the activation energy decreased as the coprecipitate was formed. X-ray diffraction study revealed the fact that metoclopramide was crystalline, in contrast, there was no crystallinity evident in the 1 : 5 metoclopramide-polyvinylpyrrolidone coprecipitate. There was no difference between physical mixture and coprecipitate in TLC, UV and NMR studies. From the comparision between physical mixture and coprecipitate in IR spectrum, the interaction such as association between metoclopramide and polyvinylpyrrolidone was considered. But the association was easily dissociated in methanol solution.

• Korean Journal of Materials Research
• /
• v.32 no.11
• /
• pp.474-480
• /
• 2022

Lithium-ion batteries (LIBs) are powerful energy storage devices with several advantages, including high energy density, large voltage window, high cycling stability, and eco-friendliness. However, demand for ultrafast charge/discharge performance is increasing, and many improvements are needed in the electrode which contains the carbon-based active material. Among LIB electrode components, the conductive additive plays an important role, connecting the active materials and enhancing charge transfer within the electrode. This impacts electrical and ionic conductivity, electrical resistance, and the density of the electrode. Therefore, to increase ultrafast cycling performance by enhancing the electrical conductivity and density of the electrode, we complexed Ketjen black and graphene and applied conductive agents. This electrode, with the composite conductive additives, exhibited high electrical conductivity (12.11 S/cm), excellent high-rate performance (28.6 mAh/g at current density of 3,000 mA/g), and great long-term cycling stability at high current density (88.7 % after 500 cycles at current density of 3,000 mA/g). This excellent high-rate performance with cycling stability is attributed to the increased electrical conductivity, due to the increased amount of graphene, which has high intrinsic electrical conductivity, and the high density of the electrode.

• Journal of Adhesion and Interface
• /
• v.4 no.2
• /
• pp.1-9
• /
• 2003

Epoxy-amine liquid prepolymers are extensively applied onto metallic substrates and cured to obtain painted materials or bonded joint structures. Overall performances of such systems depend on the created interphase between the organic layer and the substrate. When epoxy-amine liquid mixtures are applied onto more or less hydrated metallic oxide layer, concomitant amine chemical sorption and hydroxide dissolution appear lending to the chelate formation. As soon as the chelate concentration is higher than the solubility product, these species crystallize as sharp needles. Moreover, intrinsic and thermal residual stresses are developed within painted or bonded systems. When residual stresses are higher than the organic layer/substrate adhesion, buckling, blistering, debonding may occur leading to a catastrophic drop of system performances. Practical adhesion can be evaluated with either ultimate parameters (Fmax or Dmax) or the critical strain energy release rate, using the three point flexure test (ISO 14679-1997). We observe that, for the same system, the ultimate load decreases while residual stresses increase when the liquid/solid time increases. Ultimate loads and residual stresses depend on the metallic surface treatment. For these systems, the critical strain energy release rate which takes into account the residual stress profile and the Young's modulus gradient remains quite constant whatever the metallic surface treatment was. These variations will be discussed and correlate to the formation mechanisms of the interphase.

• The Korean Journal of Pesticide Science
• /
• v.9 no.3
• /
• pp.221-230
• /
• 2005

Temperature is an important ambient factor affecting the physiology and metabolism of aquatic invertebrates. In this study, we studied about the survival, reproduction and growth effects of 4 different temperatures(16, 20, 24, $28^{\circ}C$) in four Korean cladoceran, Daphnia sp., Daphnia obtusa, Moina macrocopa, Simocephalus vetulus and Daphnia magna as an international standard species. All 5 water flea tested showed that molting time, fecundity and intrinsic rate of natural increase(r) in high temperature condition were higher than those in lower temperature. On the other hand, lower survivals and longer time to start of offspring were showed in high temperature. Our results suggest that the optimal temperatures of Daphnia sp.,, Moina macrocopa and Simocephalus vetulus seem to be about $20^{\circ}C$ except for Daphnia obtusa which as showed good survivals and reproductions in $16^{\circ}C$.

• Korean journal of applied entomology
• /
• v.41 no.3
• /
• pp.211-216
• /
• 2002

The present study was aimed to examine the effect of different host plants on the biological property of cotton caterpillar, outbreak pest of cucurbit vegetables. The feeding and oviposition preferences toward cucumber and pumpkin were greater than those toward watermelon, oriental melon, and melon. The periods of egg and larva fed on oriental melon, melon, and pumpkin were longer than those on watermelon and cucumber. The longest pupal period was 10.5 days from cucumber. The hatching rate, pupation rate, emergence rate, and survival rate were observed from different host plants. The hatching rate was the highest on cucumber (87.2%) and the lowest on melon (72.8%). The pupation rate on watermelon and oriental melon (90.0% and 89.1%, respectively) was higher than that on cucumber (62.0%). The emergence rate on cucumber and pumpkin (93.5% and 92.0%, respectively) was higher than that on oriental melon (78.7%). The survival rate from hatching to emergence on watermelon (76.0%) was the highest, and the lowest on cucumber (50.0%). The adult period on melon (21.0 days) was the longest, and the shortest on cucumber (15.5 days) among 5 host plants. Average number of eggs per female on cucumber (281.8 eggs) was the highest, and the least on oriental melon (96.6 eggs). The survivorship on cucumber was the longest (30 days), and the shortest on pumpkin (17 days). The preoviposition period on oriental melon and melon (3.4 days) was longer than that on watermelon (2.1 days) and mean generation time in day (T) on melon was the longest (47.2 days) though they were not significant. The net reproductive rate per generation (R$_{o}$) on cucumber, 191.3, was the highest and the highest intrinsic rate of natural increase (r$_{m}$) was observed from cucumber as 0.127. All these results suggest that the growth ana reproduction of cotton caterpillar varies depending upon the kind of host plants. The analysis of the life table revealed that cucumber and pumpkin were the favorable host plants of cotton caterpillar.

• Applied Chemistry for Engineering
• /
• v.9 no.7
• /
• pp.950-955
• /
• 1998

The objective of this study was to investigate the effect of running time, operating pressure, feed concentration and circulation rate on the permeation flux and the rejection rate in cross-flow ultrafiltration of polyethylene glycol(PEG) solution of molecular weight($M_w$) 8000 and 20000. The membranes used for this study were MWCO(Molecular Weight Cut-off) of 6 K and 20 K. The experiments were performed at the operating pressures of 7, 14 and 28 psi, the circulation rates of 1000 mL/min and 2000 mL/min, and the feed concentration of 100 mg/L and 1000 mg/L. At a constant pressure, the permeation flux and the observed rejection($R_o$) appeared to be approximately constant within the range of running time, 0~480 min. The permeation flux increased with increasing the operating pressure, and it increased with decreasing the feed concentration and decreasing Mw of PEG at a given pressure. On the other hand, $R_o$ decreased slightly with increasing the operating pressure. However, $R_o$ increased with increasing the feed concentration and increasing of $M_w$ of PEG at a given pressure. The variation in circulation rates did not cause any significant influence on the permeation flux. Increasing of circulation rate caused the increase of $R_o$, and $\alpha$ was increased substantially with the decrease of $M_w$ of PEG. The dimensionless parameter. permeability ratio($\alpha$), which was used to investigate flux-pressure behavior, was increased with the increase in circulation rate and operating presure. The value of $\alpha$ was less than 1 in all cases. The estimated intrinsic rejection(R). which was obtained from mass transfer coefficient, was decreased with the increase of operating pressure. However R increased with the increase of linear velocity of feed and $M_w$ of PEG.

• Biomolecules & Therapeutics
• /
• v.28 no.4
• /
• pp.361-369
• /
• 2020

Tofacitinib, a Janus kinase inhibitor, was developed for the treatment of rheumatoid arthritis. Recently, it has been associated with an increased change in arthritis development in patients with diabetes. Herein, we evaluated the pharmacokinetics of tofacitinib after intravenous (10 mg/kg) and oral (20 mg/kg) administration to rats with streptozotocin-induced diabetes mellitus and control rats. Following intravenous administration of tofacitinib to rats with streptozotocin-induced diabetes mellitus, area under the plasma concentration-time curve from time zero to infinity of tofacitinib was significantly smaller (33.6%) than that of control rats. This might be due to the faster hepatic intrinsic clearance (112%) caused by an increase in the hepatic cytochrome P450 (CYP) 3A1(23) and the faster hepatic blood flow rate in rats with streptozotocin-induced diabetes mellitus than in control rats. Following oral administration, area under the plasma concentration-time curve from time zero to infinity of tofacitinib was also significantly smaller (55.5%) in rats with streptozotocin-induced diabetes mellitus than that in control rats. This might be due to decreased absorption caused by the higher expression of P-glycoprotein and the faster intestinal metabolism caused by the higher expression of intestinal CYP3A1(23), which resulted in the decreased bioavailability of tofacitinib (33.0%) in rats with streptozotocin-induced diabetes mellitus. In summary, our findings indicate that diabetes mellitus affects the absorption and metabolism of tofacitinib, causing faster metabolism and decreased intestinal absorption in rats with streptozotocin-induced diabetes mellitus.