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Consideration of Diluents Selection and Input Amounts of the Hunter Process for Tantalum Production
Jae‑Jin Sim,Sang‑Hoon Choi,Yong‑Kwan Lee,Sung Gue Heo,Taek‑Soo Kim,Seok‑Jun Seo,Kyoung‑Tae Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
Tantalum (Ta) is a heavy refractory metal with an atomic weight of 180.95 g/mol, a density of 16.6 g/cm3, and a high meltingpoint of 3017 °C. With its refractory characteristics, it shows excellent chemical and physical stability as well as corrosionand heat resistance at elevated temperatures. The demand for Ta metal and related compounds is increasing with the expansionof the electronics and chemical industries. The Hunter process was proven to be effective in producing Ta powder in1953. Hunter proposed a method in which potassium heptafluorotantalate (K2TaF7) was reduced by sodium (Na). Thus far,this process has been the primary commercial method to produce Ta powder. In this study, quantitative differences wereanalyzed for diluent selection. Additionally, consideration was given to changes in the caloric value depending on the inputamount of diluents. Finally, the optimum material input and the properties of the prepared Ta were analyzed. Stoichiometricratios of K2TaF7(1 mol), NaCl (6.2–6.7 mol), Na (5–7 mol) were weighed, to perform a metallothermic reduction reaction. After the reaction, the tantalum powder was recovered and the flush process was carried out. After that, it was dried in avacuum atmosphere. Physical properties such as oxygen concentration, PSA, ICP-OES, and XRD of powder were conductedto evaluate the characteristics of Ta powder that was finally manufactured.
Choi, Dukhyun,Choi, Min-Yeol,Choi, Won Mook,Shin, Hyeon-Jin,Park, Hyun-Kyu,Seo, Ju-Seok,Park, Jongbong,Yoon, Seon-Mi,Chae, Seung Jin,Lee, Young Hee,Kim, Sang-Woo,Choi, Jae-Young,Lee, Sang Yoon,Kim, Jo WILEY-VCH Verlag 2010 ADVANCED MATERIALS Vol.22 No.19
<B>Graphic Abstract</B> <P>The cover shows an image of fully rollable transparent nanogenerators synthesized using chemical vapor deposition grown large-scale graphene sheets as transparent electrodes and piezoelectric ZnO nanorod arrays. Sang-Woo Kim, Jae-Young Choi, and co-workers report on p. 2187 the electrical and structural stability of the nanogenerators, with excellent charge scavenging performance under external mechanical loads such as bending and rolling. This study shows that graphene-based nanogenerators are very promising for self-powered rollable transparent device applications. <img src='wiley_img_2010/09359648-2010-22-19-ADMA201090066-content.gif' alt='wiley_img_2010/09359648-2010-22-19-ADMA201090066-content'> </P>
Heavy metal concentrations in hair of newly imported China-origin rhesus macaques (Macaca mulatta)
Jae-Il Lee,Won-Young Jung,Gaeul Lee,Min-Sun Kim,Young-Seo Kim,Chung-Gyu Park,Sang-Joon Kim 한국실험동물학회 2012 Laboratory Animal Research Vol.28 No.3
Macaque monkeys are good sentinel to humans for environmental pollutions because their similarities in genetic and physiological characteristics. So, their reference values about exposures to heavy metals are required for proper data interpretation. Here, we report several heavy metals concentrations in the hair of rhesus monkeys which are widely used in biomedical research. The hair of 28 imported rhesus monkeys from an animal farm in southwest China were examined for the presence of eight heavy metals (Arsenic, Beryllium, Cadmium, Chromium, Iron, Lead, Mercury, and Selenium). The analyzed data in parts per million (ppm) for hair concentrations of heavy metals in rhesus monkeys were as follow: As (0.654±0.331), Be (0.005±0.003), Cd (0.034±0.022), Cr (11.329±4.259), Fe (87.106±30.114), Pb (0.656±0.613), Hg (0.916±0.619), and Se (3.200±0.735). The concentrations of Be, Cr, and As showed significant higher in females than in males (P<0.05). We present here the reference values of several heavy metals in healthy China-origin rhesus monkeys. These data may provide valuable information for veterinarians and investigators using rhesus monkeys in experimental studies.
Effects of dietary high fat on prostate intraepithelial neoplasia in TRAMP mice
Sung-Hoon Park,Seo-Na Chang,Min-Won Baek,Dong-Jae Kim,Yi-Rang Na,Seung-Hyeok Seok,Byoung-Hee Lee,Kyung-Sul Kim,Jae-Hak Park 한국실험동물학회 2013 Laboratory Animal Research Vol.29 No.1
Increased fat intake is known to be a major cause of prostate cancer. In this study, we investigated the effect of dietary high fat on prostate intraepithelial neoplasia using transgenic adenocarcinoma mouse prostate (TRAMP) mice. Six-week-old male TRAMP mice were fed AIN93G (control group, 4.0 kcal/kg, n=6) and AIN93G-HFD (experimental group, 4.8 kcal/kg, n=7) for 10 weeks. Prostate histopathology, urogenital tract (UGT) weight, epididymal white adipose tissue weight, argyrophilic nucleolar organizer regions (AgNORs) counts, and serum leptin levels were examined. AIN93G-HFD fed group showed progressed neoplastic lesions in the prostate (P<0.05) compared to AIN93G fed group. AIN93G-HFD intake resulted in a increase in the weight of UGT (P<0.05) and epididymal white adipose tissue. The number of Ag-NOR positive dots significantly increased in each prostate lobe and final serum leptin levels in AIN93G-HFD fed group were about twice those of AIN93G fed group (P<0.05). Dietary high fat was related to the prostate cancer progression in the early stage of TRAMP mice and increased serum leptin levels, suggesting that the regulation of dietary components could delay the progression of prostate cancer.
Jae Myun Ryu,Im Kwon Seo,Tae Myoung Kim,Yun-Bae Kim,Sung Kwon Moon,Kyung-Hwan Jung,Keerang Park,Seung Bok Hong,Seock-Yeon Hwang 한국실험동물학회 2008 Laboratory Animal Research Vol.24 No.2
The chemopreventive effects of Magnolia ovobata water extract (MWE) and 70% ethanol extract (MEE) on the development of colonic aberrant crypt foci (ACF) induced by 1,2-dimethylhydrazine (DMH) were investigated. Six-week-old male F344 rats were divided to 7 experimental groups; 1) DMH alone, 2) DMH+0.3% MWE, 3) DMH+1% MWE, 4) DMH+3% MWE, 5) DMH+1% MEE, 6) 3% MWE alone and 7) normal control. Animals were subcutaneously injected with DMH (30 mg/kg) 4 times to induce colonic ACF during the initial 2 weeks, and fed with a basal containing various concentrations of test materials (MWE or MEE) for 8 weeks including the DMH-treatment period. The formation of ACF on colonic mucosa was observed after staining with methylene blue. There are no specific effects of MWE and MEE on body weight, feed and water consumptions, organ weights, histopathological observations, and hematological and blood chemistry analyses. Challenge with DMH alone induced mean number of 270.1 ACF/colon which was somewhat inhibited by MWE treatment, showing average numbers of 234.3-242.1 ACF/colon. In comparison, the ACF number was significantly suppressed to 216.5 by administration of 1% MEE. Therefore, these results suggest that Magnolia ovobata extracts, especially MEE, exert a chemopreventive effect on the DMH-induced colon cancer by inhibiting the early development of ACF.
Improved oral absorption of cilostazol via sulfonate salt formation with mesylate and besylate
Seo, Jae Hong,Park, Jung Bae,Choi, Woong-Kee,Park, Sunhwa,Sung, Yun Jin,Oh, Euichaul,Bae, Soo Kyung Dove Medical Press 2015 Drug design, development and therapy Vol.9 No.-
<P><B>Objective</B></P><P>Cilostazol is a Biopharmaceutical Classification System class II drug with low solubility and high permeability, so its oral absorption is variable and incomplete. The aim of this study was to prepare two sulfonate salts of cilostazol to increase the dissolution and hence the oral bioavailability of cilostazol.</P><P><B>Methods</B></P><P>Cilostazol mesylate and cilostazol besylate were synthesized from cilostazol by acid addition reaction with methane sulfonic acid and benzene sulfonic acid, respectively. The salt preparations were characterized by nuclear magnetic resonance spectroscopy. The water contents, hygroscopicity, stress stability, and photostability of the two cilostazol salts were also determined. The dissolution profiles in various pH conditions and pharmacokinetic studies in rats were compared with those of cilostazol-free base.</P><P><B>Results</B></P><P>The two cilostazol salts exhibited good physicochemical properties, such as nonhygroscopicity, stress stability, and photostability, which make it suitable for the preparation of pharmaceutical formulations. Both cilostazol mesylate and cilostazol besylate showed significantly improved dissolution rate and extent of drug release in the pH range 1.2–6.8 compared to the cilostazol-free base. In addition, after oral administration to rats, cilostazol mesylate and cilostazol besylate showed increases in <I>C</I><SUB>max</SUB> and AUC<I><SUB>t</SUB></I> of approximately 3.65- and 2.87-fold and 3.88- and 2.94-fold, respectively, compared to cilostazol-free base.</P><P><B>Conclusion</B></P><P>This study showed that two novel salts of cilostazol, such as cilostazol mesylate and cilostazol besylate, could be used to enhance its oral absorption. The findings warrant further preclinical and clinical studies on cilostazol mesylate and cilostazol besylate at doses lower than the usually recommended dosage, so that it can be established as an alternative to the marketed cilostazol tablet.</P>
Seo, Hyogi,Seungwoo Seo,Sanggeun Jeon,Jae-Sung Rieh IEEE 2011 IEEE microwave and wireless components letters Vol.21 No.6
<P>An injection-locked frequency divider (ILFD) with an inductive feedback for enhanced locking range has been developed in a commercial 0.13 μm Si RFCMOS technology and compared with a conventional ILFD. The proposed ILFD showed a significant improvement in the locking range over the conventional ILFD, operating at a frequency range of 43.60-48.95 GHz. The dc power consumption of the ILFD was 0.58 mW with a supply voltage of 1.2 V for the divider core.</P>
Thirteen-Week Repeated-Dose Oral Toxicity of Licorice Root in F344 Rats
Sang-Bum Koh,Jae-Hwang Jeong,Mu-Yeb Seo,Jun-Yeon Lee,Dong-Seok Seo,Hak-Soo Bark,Myung-Hwa Kang,Dae-Yong Kim,Ha-Jung Sung 한국실험동물학회 2006 Laboratory Animal Research Vol.22 No.1
The purpose of this study is to investigate a potential toxicity of licorice root (LR) in Fisher 344 rats through the 13-week repeated oral treatment. Healthy Fisher 344 rats were divided into five treatment groups (2,000, 571, 163, 47, and 13 ㎎/㎏) and one control group (vehicle) of 12 males and 12 females respectively. LR was orally administered by gavage to F344 rats once a day, 5 days per week for 13 weeks. During the test period, clinical signs, mortality, body weights, necropsy findings, hematology, serum biochemistry, organ weight, histopathology, sperm count and sperm motility were evaluated. The relative liver weights were increased significantly in males of the 2,000 and 571 ㎎/㎏ groups. However, there was no histological evidence in the liver. The increased incidence of chronic nephropathy only appeared in the 2,000 ㎎/㎏ group of both male and female rats. There were no treatment-related effects on clinical signs, mortality, body weights, necropsy findings, hematology, serum biochemistry and sperm count and motility in any treatment groups. Based on these results, no-observed adverse effect level (NOAEL) of LR was 571 ㎎/㎏ in F344 rats under the conditions of the present study.