Solubility of oxcarbazepine in eight solvents within the temperature range T=(288.15-308.15)K

Nam, K.,Ha, E.S.,Kim, J.S.,Kuk, D.H.,Ha, D.H.,Kim, M.S.,Cho, C.W.,Hwang, S.J. Academic Press 2017 The Journal of chemical thermodynamics Vol.104 No.-

In this study, the solubility of oxcarbazepine in pure methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, acetonitrile, and tetrahydrofuran was analysed across the temperature range of 288.15-308.15K under atmospheric pressure by using a solid-liquid equilibrium method. The experimental values obtained data were correlated using the modified Apelblat model at each temperature. The mole fraction solubility of oxcarbazepine in all eight pure solvents increased gradually in a temperature-dependent manner. The highest mole fraction solubility of 3.08x10<SUP>-3</SUP> at 308.15K was observed for tetrahydrofuran, followed by acetone (1.82x10<SUP>-3</SUP> at 308.15K), acetonitrile (1.22x10<SUP>-3</SUP> at 308.15K), methanol (1.11x10<SUP>-3</SUP> at 308.15K), ethanol (6.17x10<SUP>-4</SUP> at 308.15K), 1-butanol (6.17x10<SUP>-4</SUP> at 308.15K), 1-propanol (6.16x10<SUP>-4</SUP> at 308.15K), and 2-propanol (4.13x10<SUP>-4</SUP> at 308.15K). The experimental solubility in all solvents correlated well with that calculated using the modified Apelblat equation across the temperature range of (288.15-308.15)K. Therefore, the experimental solubility and correlation equations established in this study could be useful during the crystallization/purification, pre-formulation, and formulation stages of oxcarbazepine production in laboratories and related industries.

Relationship Between K_trans and K₁ with Simultaneous Versus Separate MR/PET in Rabbits with VX2 Tumors

Lee, K. H.,Kang, S. K.,Goo, J. M.,Lee, J. S.,Cheon, G. J.,Seo, S.,Hwang, E. J. INTERNATIONAL INSTITUTE OF ANTICANCER RESEARCH 2017 Anticancer research Vol.37 No.3

<P>Background/Aim: To compare the relationship between Ktrans from DCE-MRI and K1 from dynamic (NNH3)-N-13- PET, with simultaneous and separate MR/PET in the VX-2 rabbit carcinoma model. Materials and Methods: MR/PET was performed simultaneously and separately, 14 and 15 days after VX-2 tumor implantation at the paravertebral muscle. The Ktrans and K-1 values were estimated using an in-house software program. The relationships between Ktrans and K-1 were analyzed using Pearson's correlation coefficients and linear/non-linear regression function. Results: Assuming a linear relationship, Ktrans and K-1 exhibited a moderate positive correlations with both simultaneous ( r=0.54-0.57) and separate ( r=0.53-0.69) imaging. However, while the Ktrans and K-1 from separate imaging were linearly correlated, those from simultaneous imaging exhibited a non-linear relationship. The amount of change in K-1 associated with a unit increase in Ktrans varied depending on Ktrans values. Conclusion: The relationship between K-trans and K-1 may be mis-interpreted with separate MR and PET acquisition.</P>

Strain selection and initiation timing influence the cultivation period of Saccharina japonica and their impact on the abalone feed industry in Korea

Hwang, E. K.,Ha, D. S.,Park, C. S. Springer Science + Business Media 2017 Journal of applied phycology Vol.29 No.5

<P>Cultivations of the brown seaweed, Saccharina japonica, was developed, promoted, and industrialized in the 1970s and is highly valued in Korea both for human consumption and as a feed for the rapidly developing abalone farming industry. Production has continually increased, and approximately 442,637 tonnes wet weight was harvested in Korea in 2015. Abalone is a highly sought-after delicacy in Korea, and the abalone farming industry has been developed based on a stable production of seaweed. Korean abalone farmers prefer to feed their stock on locally cultured S. japonica; however, between August and November, the supply of farmed S. japonica declines because higher seawater temperatures reduce S. japonica productivity. In an attempt to overcome this temperature-induced period of low production, cultivation trials with a strain of S. japonica selected to withstand higher cultivation temperatures were undertaken. Strain selection involved using individual parent thalli that were found to remain productive under high seawater temperature (26 A degrees C) at Wando. Male and female gametophytes were isolated through 3 cycles of free-living gametophyte culture to produce the F-3 strain used in the production trials. Production trials using the selected strain were initiated every month between December 2014 and March 2015. This delayed the initiation of culture beyond the latest initiation time currently used by farmers (December). Delaying initiation of cultivation resulted in delayed maximum growth compared to the control. Growth of the F-3 strain continued for up to 3 months longer than normally achieved on farms for non-selected thalli. The mean length, growth rate, and biomass were also greater than those achieved by the control strain. The use of the F-3 strain of S. japonica coupled with delayed initiation of culture can therefore be used to help to ensure a stable year round algal feed supply for abalone industry in Korea.</P>

A multi-membrane reformer for the direct production of hydrogen via a steam-reforming reaction of methane

Hwang, K.R.,Lee, C.B.,Ryi, S.K.,Lee, S.W.,Park, J.S. Pergamon Press ; Elsevier Science Ltd 2012 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.37 No.8

We designed and prepared a multi-membrane reformer (MMR) for the direct production of hydrogen via a steam-reforming (SR) reaction of methane. The MMR consisted of two single modules containing coin-shaped nickel metal catalysts and Pd-based membrane. The SR reaction was performed in the MMR for relatively high-pressure operation ranges (P<SUB>2</SUB> = ∼21 bar) without sweep gas and the methane conversion and hydrogen production rate were observed under various experimental conditions. It was found that the high-performance of the Pd-based membrane and the porous metal catalyst and their configuration in the MMR guaranteed a high rate of hydrogen production. For instance, the methane conversion, the rate of hydrogen separation and the hydrogen purity were 75%, 30.6 L/h and 99.95%, respectively, under the experimental conditions of 540 <SUP>o</SUP>C, S/C = 3.0 and del-P = 20 bar. The design and performance of MMR show potential advantages, such as the simple preparation of a compact membrane reformer able to operate in relatively high-pressure ranges and easy enlargement of the hydrogen production capacity by stacking the modules, which is possible due to the disk-type shape of the metal catalyst and the membrane.

복합재료 특성 평가 1 : 다축 구조 S-2 유리섬유 복합재의 충격 특성

송승욱 ( S. W. Song ),이창훈 ( C. H. Lee ),변준형 ( J. H. Byun ),황병선 ( B. S. Hwang ),엄문광 ( M. K. Um ),이상관 ( S. K. Lee ) 한국복합재료학회 2005 한국복합재료학회 학술발표대회 논문집 Vol.- No.1

Phenol content, antioxidant and tyrosinase inhibitory activity of mangrove plants in Micronesia

Suh, S.S.,Hwang, J.,Park, M.,Park, H.S.,Lee, T.K. Elsevier 2014 Asian Pacific journal of tropical medicine Vol.7 No.7

Objective: To find out and compare the in vitro antioxidant and tyrosinase inhibitory activities of two species of mangrove plants. Methods: Mangrove samples were harvested at the shoreline on the island of Weno, Chuuk State in Micronesia. The phenol content, antioxidant activity (based on DPPH-free radical scavenging) and tyrosinase inhibitory activity in different tissues (leaves, barks and roots) of Rhizophora stylosa (R. stylosa) and Sonneratia alba (S. alba), collected from the island of Weno. Results: Total phenol content ranged from 4.87 to 11.96 mg per g of freeze dried samples. The highest antioxidant activity was observed in R. stylosa bark (85.5%). The highest tyrosinase inhibitory activity was found in S. alba bark. Also, total phenol content and antioxidant activity were higher in methanol extracts than in aqueous extracts. Conclusions: Taken together, the results of this study proved that mangroves can be excellent sources of antioxidant compounds.

Repair of Pd-based composite membrane by polishing treatment

Ryi, S.K.,Park, J.S.,Hwang, K.R.,Lee, C.B.,Lee, S.W. Pergamon Press ; Elsevier Science Ltd 2011 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.36 No.21

In this study, polishing treatment was introduced to repair Pd-based composite membrane. Some pinholes remained after sputtering with palladium followed by heat-treatment at 723 K for 2 h. The pinholes drastically decreased the hydrogen perm-selectivity of the Pd-based composite membrane. In order to remove the pinholes, we introduced polishing treatment after the palladium sputtering. Scanning election microscopy (SEM) analysis and helium leak tests confirmed the effectiveness of the polishing treatment in removing the pinholes. The helium leaks were drastically decreased by the polishing treatment. Hydrogen permeation and helium leak tests showed that the polishing treatment increased the hydrogen perm-selectivity from 52 to >40,000 with a hydrogen permeation flux of 1.8 x 10<SUP>-1</SUP> mol m<SUP>-2</SUP> s<SUP>-1</SUP> at a pressure difference of 100 kPa and temperature of 673 K. The advantage of our membrane fabrication procedures lies in its simplicity. Our coating and polishing method offers the promise of highly reproducible Pd-based composite membrane.

TWB 보론강의 기계적 특성 및 성형성

남기우(K. W. Nam),황석환(S. H. Hwang),김대용(D. Y. Kim),이문용(M. Y. Lee),이상문(S. M. Lee) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.10

핫 스탬핑은 오스테나이트 변태 온도 이상에서 프레스 성형 후 급속히 냉각되는 고강도 부품을 제조하는 성형 방법이다. 매우 적은 양의 보론 성분을 가지고 있는 보론강은 핫 스탬핑에 사용되는 재료 중의 하나이다. 본 연구의 목적은 열처리 조건에 따르는 기계적 성질과 에릭슨 커핑 시험에 의하여 성형성을 조사하는 것이다. 다양한 온도에서 다이퀜칭은 대기 시간을 달리하여 실시하였다. 1173 K-0s에서 퀜칭 후 TWB는 1203 MPa의 인장 강도를 얻었다. 이것은 모재 인장강도(1,522 MPA)의 79 %이다. 금형 온도(298, 523, 673 K)에 따른 보론강 TWB의 성형성은 차이가 크지 않았다. 그러나 성형 속도가 증가함에 따라 성형성이 감소하는 것을 확인할 수 있었다. The hot-stamping technique is a forming method used for manufacturing high-strength parts, in which a part is cooled rapidly after press forming above the austenite transformation temperature. Boron steel, which contains a very small amount of boron, is one of the materials used for hot stamping. The purpose of this study is to investigate the mechanical properties of boron steel according to the heat-treatment conditions and the formability by using an Erichsen cupping test. Die quenching from various temperatures was conducted for different elapsed heat-treatment times. Laser-welded boron steel after quenching at 1173 K-0 s has a tensile strength of 1203 MPa. This is 79% of the tensile strength of the base metal (1522 MPa). The formability of boron steel was not significantly different from that at the mold temperature. However, it decreased with increasing forming speed. These properties provide practical information for the use of boron steels for hot stamping.

The Magnetic Entropy Change on La<SUB>0.7</SUB>Ba<SUB>0.3</SUB>Mn<SUB>1-x</SUB>Fe<SUB>x</SUB>O₃ Compound

J. S. Hwang,D. M. Jang,K. S. Kim,J. S. Lee,S. C. Yu 한국자기학회 2013 Journal of Magnetics Vol.18 No.1

The magnetocaloric effect and magnetization behavior have been analyzed in the double-perovskite La0.7Ba0.3Mn1-XFeXO₃ compound with the sintering temperature at 1273 K. Samples were fabricated by the conventional solid-state reaction method. X-ray diffraction measurement revealed that all the samples had a single phase in orthorhombic. Detailed investigations of the magnetic entropy behavior of the samples were discussed with the variation of TC. The magnetic entropy changes, ΔSM of approximately 0.36-1.14 J/㎏ K were obtained in the temperature range of 145-350 K for the La0.7Ba0.3Mn1-XFeXO₃ compound. The enhancement of the magnetic entropy change is believed to be due to changes in the microstructure, which changes the magnetic part of the entropy of a solid around the magnetic ordering temperature.

Korean red ginseng extract rejuvenates testicular ineffectiveness and sperm maturation process in aged rats by regulating redox proteins and oxidative defense mechanisms

Kopalli, S.R.,Hwang, S.Y.,Won, Y.J.,Kim, S.W.,Cha, K.M.,Han, C.K.,Hong, J.Y.,Kim, S.K. Pergamon Press ; Elsevier Science Ltd 2015 Experimental Gerontology Vol.69 No.-

Distortion of intracellular oxidant and antioxidant balances appears to be a common feature that underlies in age-related male sexual impairment. Therefore regulating oxidative defense mechanisms might be an ideal approach in improving male sexual dysfunctions. In the present study, the effect of Korean red ginseng aqueous extract (KRG) on age-induced testicular dysfunction in rats was investigated. KRG (200mg/kg) mixed with regular pellet diet was administered orally for six months and the morphological, spermatogenic and antioxidant enzyme status in testis of aged rats (18months) were evaluated. Data indicated a significant change in morphology and decrease in spermatogenesis-related parameters in aged rats (AC) compared with young rats (YC). Sperm number, germ cell count, Sertoli cell count and Sertoli cell index were significantly (p<0.05) restored in KRG-treated aged rat groups (G-AC). Further the increased lipid peroxidation as measured by malondialdehyde (p<0.05), and altered enzymatic (superoxide dismutase, glutathione peroxidase, glutathione S-transferase, glutathione reductase and catalase) and non-enzymatic (reduced glutathione, ascorbic acid and α-tocopherol) antioxidants (p<0.05) were attenuated by KRG treatment in aged rats to near normal levels as in YC groups. Furthermore, proteomic analysis demonstrated differential expression of selected proteins such as phosphatidylinositol transfer protein, fatty acid binding protein-9, triosephosphate isomerase-1 and aldehyde (aldose) reductase-1in aged rats was significantly (p<0.05) protected by KRG treatment. In conclusion, long-term administration of KRG restored aging-induced testicular ineffectiveness in rats by modulating redox proteins and oxidative defense mechanisms.