• Advances in Traditional Medicine
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• 제7권5호
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• pp.477-484
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• 2008

The present study was aimed at investigating the hypouricemic and xanthine oxidase inhibitory activities of the various fractions of the hydromethanolic extract of the leaves of Coccinia grandis L. Voigt (Cucurbitaceae). The leaves of this species was used in traditional medicinal system for the treatment of gout, rheumatism, jaundice, bronchitis, fever, skin eruptions, wounds, etc. The degree of xanthine oxidase inhibition was determined in vitro by measuring the increase in absorbance at 295 nm associated with uric acid formation. Among the fractions tested, the chloroform fraction exhibited highest potency ($IC_{50}$ $17.8\;{\mu}g/ml$). This was followed by the pet-ether ($IC_{50}$ $29.7\;{\mu}g/ml$), ethyl acetate ($IC_{50}$ $41.2\;{\mu}g/ml$) and residual ($IC_{50}$ $47\;{\mu}g/ml$) fractions. The $IC_{50}$ value of allopurinol was $6.1\;{\mu}g/ml$. In addition, the hypouricemic and hepatic xanthine oxidase (XO)/xanthine dehydrogenase (XDH) inhibitory activities of the fractions were examined in vivo using oxonate (280 mg/kg, i.p.) induced hyperuricemic mice. At a dose of 200 mg/kg orally for 7 days, the pet-ether, chloroform and ethyl acetate fractions produced a significant (P < 0.01) reduction in serum urate level and also inhibited hepatic XO/XDH activities when compared to hyperuricemic mice. These inhibitory effects were weaker than that observed for the standard drug, allopurinol (10 mg/kg, p.o.). Lineweaver-Burk analysis of the enzyme kinetics indicated that the mode of inhibition was of a mixed type. These results suggest that the use of Coccinia grandis leaves for the treatment of gout could be attributed to its XO inhibitory activity.

• The Korean Journal of Physiology and Pharmacology
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• 제5권5호
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• pp.413-421
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• 2001

An impaired smooth muscle cell (SMC) relaxation of coronary artery by alteration of $K^+$ channels would be the most potential explanation for reduced coronary reserve in left ventricular hypertrophy (LVH), however, this possibility has not been investigated. We performed morphometrical analysis of the coronary artery under electron microscopy and measured $Ca^{2+}-activated\;K\;(K_{Ca})$ currents and delayed rectifier K $(K_{dr})$ currents by whole-cell and inside-out patch-clamp technique in single coronary arterial SMCs from rabbits subjected to isoprenaline-induced cardiac hypertrophy. Coronary arterial SMCs underwent significant changes in ultrastructure. The unitary current amplitude and the open-state probability of $K_{Ca}$ channel were significantly reduced in hypertrophy without open-time and closed-time kinetic. The concentration-response curve of $K_{Ca}$ channel to $Ca^{2+}$ is shifted to the right in hypertrophy. The reduction in the mean single channel current and increase in the open channel noise of $K_{Ca}$ channel by TEA were more sensitive in hypertrophy. $K_{dr}$ current density is significantly reduced in hypertrophy without activation and inactivation kinetics. The sensitivity of $K_{dr}$ current on 4-AP is significantly increased in hypertrophy. This is the first study to report evidence for alterations of $K_{Ca}$ channels and $K_{dr}$ channels in coronary SMCs with LVH. The findings may provide some insight into mechanism of the reduced coronary reserve in LVH.

• 공업화학
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• 제10권8호
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• pp.1109-1113
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• 1999

함침법에 의하여 제조된 $Pt/MoO_3$와 $Pt/MoO_3/SiO_2$ 및 $Pt^{\circ}$와 $MoO_3$를 기계적으로 혼합한 촉매를 사용한 $50^{\circ}C$ 등온 환원 실험에서 소성 온도가 증가할수록, $H_2$ spillover에 의하여 Pt로부터 $MoO_3$로 이동하여 저장되는 $H_2$가 증가하는 것을 측정하였다. 연속적으로 실행한 CO chemisorption에 의하여 $H_2$ spillover에 참가하는 $H_2$에 노출된 Pt 표면적이 감소하는 것을 알 수 있었다. 또한, TEM 결과로부터 $400^{\circ}C$에서 소성 후 Pt결정 표면에 $MoO_x$ overlayer가 형성되는 것을 관찰하였다. 그러므로, 표면 형상 변화에 따른 Pt과 $MoO_3$간의 활성접촉점 증가가 $H_2$ spillover에 의한 $MoO_3$로의 $H_2$ 이동을 증가시키는 원인 중의 하나인 것으로 판명된다.

• Carbon letters
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• 제18권
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• pp.49-55
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• 2016

Refuse-derived fuel (RDF) produced using municipal solid waste was pyrolyzed to produce RDF char. For the first time, the RDF char was used to remove aqueous copper, a representative heavy metal water pollutant. Activation of the RDF char using steam and KOH treatments was performed to change the specific surface area, pore volume, and the metal cation quantity of the char. N₂ sorption, Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and Fourier transform infrared spectroscopy were used to characterize the char. The optimum pH for copper removal was shown to be 5.5, and the steam-treated char displayed the best copper removal capability. Ion exchange between copper ions and alkali/alkaline metal cations was the most important mechanism of copper removal by RDF char, followed by adsorption on functional groups existing on the char surface. The copper adsorption behavior was represented well by a pseudo-second-order kinetics model and the Langmuir isotherm. The maximum copper removal capacity was determined to be 38.17 mg/g, which is larger than those of other low-cost char adsorbents reported previously.

• Archives of Pharmacal Research
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• 제24권6호
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• pp.568-571
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• 2001

The purpose of this work was to study the effect of storage time and temperature on the in vitro release kinetics of a commercial sustained-release dosage form of theophylline, at different pHs of the dissolution medium. The formulation was stored at $35^{\circ}C$ for 16 months and at $45^{\circ}C$ for 8 months, with a relative humidity of 60%. The in vitro release tests were performed at pHs 2, 4, 6 and 7.4. The mean values of the transport coefficient n, were close to 0.5 in all the conditions tested, which indicates that the transport system is not modified after storage of the formulation at $35^{\circ}C$ and $45^{\circ}C$. The mean values of the dissolution rate constant ranged from 0.036 to 0.043 $min^{-n}$, under all the conditions tested. Significant differences (${\alpha}=0.05$) were found between pHs 2, 4 and 6, 7.4 for all the model-independent parameters studied. When the formulation was kept at $35^{\circ}C$ for 16 months, the mean percentage of drug dissolved at 8 hours was 25.61% (pHs 2, 4) and, 36.12% (pHs 6, 7.4), representing a 26% and 24% reduction, respectively. Simitar results were obtained after storing the formulation at $45^{\circ}C$ for 8 months, corresponding to 33.3% (pHs 2, 4) and, 22.5% (pHs 6, 7.4) diminution, respectively. The values of the similarity factory $f_2$, obtained were lower than 50, which indicates the lack of similarity among the dissolution profiles, after storing the formulation under the experimental Conditions tested.

• Journal of Ceramic Processing Research
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• 제19권5호
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• pp.372-377
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• 2018

MgO or gadolinium-doped ceria (GDC, $Ce_{0.9}Gd_{0.1}O_{2-{\delta}}$) was added as a promoter to improve the oxygen transfer kinetics of $MgMnO_3$ oxygen carrier material for chemical looping combustion. Neither MgO nor GDC reacted with $MgMnO_3$, even at the high temperature of $1100^{\circ}C$. The average oxygen transfer capacities of $MgMnO_3$, 5 wt% $MgO-MgMnO_3$, and 5 wt% $GDC-MgMnO_3$ were 8.74, 8.35, and 8.13 wt%, respectively. Although the addition of MgO or GDC decreased the oxygen transfer capacity, no further degradation was observed during their use in 5 redox cycles. The addition of GDC significantly improved the conversion rate for the reduction reaction of $MgMnO_3$ compared to the use of MgO due to an increase in the surface adsorption process of $CH_4$ via oxygen vacancies formed on the surface of GDC. On the other hand, the conversion rates for the oxidation reaction followed the order 5 wt% $GDC-MgMnO_3$ > 5 wt% $MgO-MgMnO_3$ >> $MgMnO_3$ due to morphological change. MgO or GDC particles suppressed the grain growth of the reduced $MgMnO_3$ (i.e., (Mg,Mn)O) and increased the specific surface area, thereby increasing the number of active reaction sites.

• 공업화학
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• 제33권3호
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• pp.279-283
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• 2022

반응물과 생성물이 자외선 및 가시광선 영역에서 빛을 흡수하는 경우 시료의 농도 및 화학반응의 특성을 평가하는데 자외선가시광선분광법을 사용할 수 있다. 하지만 고농도와 높은 반응 온도 조건에서는 자외선가시광선분광법을 사용하는데 한계가 존재한다. 색을 가지고 있는 시료의 촉매 반응을 색상 분석으로 농도 및 조성을 외부에서 수집한 이미지를 분석하여 자외선가시광선분광법에서 동일한 결과를 얻을 수 있다. Resazurin은 촉매 및 환원제에 의해 resorufin으로 환원되며 농도에 따라 적색변광이 일어나며 카메라를 통해 수집하여 분석할 수 있다. 색상 분석을 위한 색공간은 CIE L^*a^*b^*를 사용하였고 소프트웨어를 통해 각각의 색상좌표 값을 추출하고 각 시료의 농도를 분석하였다. 시료의 농도와 촉매 반응에 대해 색공간을 이용한 분석법과 자외선가시광선분광법의 결과와 비교하여 제시된 방법의 유효성을 확인할 수 있다. 더욱이 색상 분석을 통한 농도 분석에서는 자외선가시광선분광법과 다르게 흡수파장이 중복이 있는 경우에도 디콘볼루션 없이 독립적으로 두 물질의 농도 측정이 가능하다.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.57-67
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• 2022

The curing characteristics of naphthalene type epoxy resin systems according to the change of curing agent were investigated to develop a new next-generation EMC(Epoxy Molding Compound) with excellent warpage characteristics, low thermal expansion, and excellent fluidity for WLP(Wafer Level Package). As epoxy resins, DGEBA, which are representative bisphenol type epoxy resins, NE-16, which are the base resins of naphthalene type epoxy resins, and NET-OH, NET-MA, and NET-Epoxy resins newly synthesized based on NE-16 were used. As a curing agent, DDM (Diamino Diphenyl Methane) and CBN resin with naphthalene moiety were used. The curing reaction characteristics of these epoxy resin systems with curing agents were analyzed through thermal analysis experiments. In terms of curing reaction mechanism, DGEBA and NET-OH resin systems follow the nth curing reaction mechanism, and NE-16, NET-MA and NET-Epoxy resin systems follow the autocatalytic curing reaction mechanism in the case of epoxy resin systems using DDM as curing agent. On the other hand, it was found that all of them showed the nth curing reaction mechanism in the case of epoxy resin systems using CBN as the curing agent. Comparing the curing reaction rate, the epoxy resin systems using CBN as the curing agent showed a faster curing reaction rate than them with DDM as a hardener in the case of DGEBA and NET-OH epoxy resin systems following the same nth curing reaction mechanism, and the epoxy resin systems with a different curing mechanism using CBN as a curing agent showed a faster curing reaction rate than DDM hardener systems except for the NE-16 epoxy resin system. These reasons were comparatively explained using the reaction rate parameters obtained through thermal analysis experiments. Based on these results, low thermal expansion, warpage reduction, and curing reaction rate in the epoxy resin systems can be improved by using CBN curing agent with a naphthalene moiety.

• 공업화학
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• 제34권1호
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• pp.51-56
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• 2023

광촉매 기반의 수처리 공정에서 TiO₂ 나노입자와 기공형 고분자로 구성된 복합체 멤브레인은 광촉매 반응후 나노입자를 회수하기 용이하다는 장점과 멤브레인 파울링(fouling) 억제가 가능하다는 측면에서 다양하게 연구되어 왔다. 하지만, TiO₂ 나노입자가 복합체 멤브레인에 고착된 이후 나노입자의 광촉매 특성이 어떻게 변할지에 대한 연구는 상대적으로 많이 진행되지 않았다. 이러한 측면에서, 본 연구에서는 polyethersulfone (PES)/TiO₂ 복합체 멤브레인을 제조하고 유기염료분해 반응에 대한 광촉매 특성을 연구하였다. 복합체 멤브레인에 고착된 TiO₂ 나노입자의 염료분해반응 속도를 콜로이드 상에서 분산된 TiO₂ 나노입자와 비교함으로써 멤브레인에 고착화되기 전후의 TiO₂ 나노입자의 촉매 효율을 비교하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제27권5호
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• pp.481-491
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• 2023

The β subunits of high voltage-gated calcium channels (HGCCs) are essential for optimal channel functions such as channel gating, activation-inactivation kinetics, and trafficking to the membrane. In this study, we report for the first time the potent blood pressure-reducing effects of peptide fragments derived from the β subunits in anesthetized and non-anesthetized rats. Intravenous administration of 16-mer peptide fragments derived from the interacting regions of the β1 [cacb1(344-359)], β2 [cacb2(392-407)], β3 [cacb3(292-307)], and β4 [cacb4(333-348)] subunits with the main α-subunit of HGCC decreased arterial blood pressure in a dose-dependent manner for 5-8 min in anesthetized rats. In contrast, the peptides had no effect on the peak amplitudes of voltage-activated Ca²⁺ current upon their intracellular application into the acutely isolated trigeminal ganglion neurons. Further, a single mutated peptide of cacb1(344-359)-cacb1(344-359)_K357R-showed consistent and potent effects and was crippled by a two-amino acid-truncation at the N-terminal or C-terminal end. By conjugating palmitic acid with the second amino acid (lysine) of cacb1(344-359)_K357R (named K2-palm), we extended the blood pressure reduction to several hours without losing potency. This prolonged effect on the arterial blood pressure was also observed in non-anesthetized rats. On the other hand, the intrathecal administration of acetylated and amidated cacb1(344-359)_K357R peptide did not change acute nociceptive responses induced by the intradermal formalin injection in the plantar surface of rat hindpaw. Overall, these findings will be useful for developing antihypertensives.