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Tetraglyme-mediated synthesis of Pd nanoparticles for dehydrogenation of ammonia borane
Kim, Sung-Kwan,Kim, Tae-Jin,Kim, Tae-Young,Lee, Gaehang,Park, Joon T.,Nam, Suk Woo,Kang, Sang Ook The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.14
<P>Palladium nanoparticles (PdNPs) were conveniently prepared in tetraglyme (TG) solution using a variety of palladium precursors. At 140 °C, TG promoted Pd<SUB>3</SUB>(OAc)<SUB>6</SUB> to produce irregular shaped PdNPs with an average size of 4 nm. When these PdNPs were re-dispersed in TG and used for the dehydrogenation of ammonia borane (AB) at 85 °C, remarkably enhanced catalytic performance was achieved to release 2.3 equiv. of H<SUB>2</SUB> in 1 h.</P> <P>Graphic Abstract</P><P>4 nm size-controlled palladium nanoparticles were conveniently prepared from a tetraglyme solution at 140 °C using an organometallic precursor, Pd<SUB>3</SUB>(OAc)<SUB>6</SUB>. These PdNPs catalyzed dehydrogenation of ammonia borane at 85 °C to liberate 2.3 equiv. H<SUB>2</SUB> in 1 h. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc15931g'> </P>
Kim Dae-Soo,Chung Young-Baek,Kang Sang-Ook,Ko Jae-Jung Korean Chemical Society 1992 Bulletin of the Korean Chemical Society Vol.13 No.3
The paramagnetic complex of $(CO)_4ReL_2[L_2=$ 2,3-Bis(diphenylphosphino)maleic anhydride] was prepared both by the photochemically induced homolytic splitting of $Re_2(CO)_10withL_2and$ by the chemical reduction of $[(CO)_4ReL_2]SO_3CF_3.$ The $(CO)_4ReL_2$ compound was characterized by ESR spectrum. The spectrum exhibits three group of sextets arising from one $^{185.187}Re$ nucleus (Ⅰ= 5/2) and two equivalent $^31P$ nuclei (Ⅰ= 1/2). Infrared, ESR, and cyclic voltammetric data are reported for all of the complexes prepared in this study.
44-Homooligomycin E, a New Cytotoxic Macrolide Antibiotic from Streptomyces ostreogriseus
KIM, Hang Sub,BANG, Hee Jae,LEE, Sang Yong,Yoo, Ook Joon,YOO, Jin Cheol,KIM, Young Ho,LEE, Jung Joon 朝鮮大學校 1998 藥學硏究誌 Vol.19 No.2
Homooligomycin E (1) was isolated from the culture broth of Streptomyces ostreogriseus and its structure was analyzed on the basis of physicochemical and spectroscopic data. It showed strong cytotoxicity against several human tumor cell lines.
Kim, Suk-Weon,Ban, Sung-Hee,Jeong, Soon-Chun,Chung, Hwa-Jee,Ko, Suk-Min,Yoo, Ook-Joon,Liu, Jang R. Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.6
When whole cell extracts are subjected to proton nuclear magnetic resonance spectroscopy $(^1H\;NMR)$, metabolite profiles are generated that contain overlapping signals of the majority of compounds within the extract. In order to determine whether pattern recognition based on the metabolite profiles of higher plants is able to genetically discriminate between plants, we analyzed leaf samples of eight cultivars of Catharanthus roseus by $^1H$ NMR. Hierarchical dendrograms, based on the principal component analysis of the $^1H$ NMR total, aliphatic, carbohydrate, and aromatic region data, revealed possible relationships between the cultivars. The dendrogram based on the aromatic region data was in general agreement with the genetic relationships determined by conventional DNA fingerprinting methods. Secologanin and polyphenols were assigned to the signals of the $^1H$ NMR spectra, and contributed most profoundly to the discrimination between cultivars. The overall results indicate that the genetic relationships between C. roseus cultivars are reflected in the differences of the aromatic compounds in the leaves.
Herbal formulation MIT ameliorates high-fat diet-induced non-alcoholic fatty liver disease
Sang-hyun Ahn,Eun-Sun Yang,Hey-Rin Cho,Syng-Ook Lee,Ki-Tae Ha,Kibong Kim 한국한의학연구원 2020 Integrative Medicine Research Vol.9 No.4
Background: Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases and is caused by obesity, diabetes, high blood pressure, and insulin resistance. Many studies have explored novel candidates to treat NAFLD using herbal medicines owing to their fewer side effects. In this study, we examined the effect of MIT, an herbal formula comprising Ephedra sinica, Panax ginseng, and Alisma orientale, on the murine model of NAFLD. Methods: To evaluate the effect of MIT on NAFLD, we used the high-fat diet (HFD)-induced NAFLD mice model. The mice were divided into four groups: control, HFD, HFD with metformin administration, and HFD with MIT administration. Freeze-dried MIT was dissolved in phosphate buffered saline and orally administered for 8 weeks to MIT-treated mice (60 mg/kg) after feeding them with HFD for 16 weeks. Results: MIT treatment significantly attenuated fat accumulation, serum glucose levels, and excessive cholesterol. It also reduced the activation of NF-κB, JNK, ERK, mammalian target of rapamycin, and peroxisome proliferator-activated receptor γ in the HFD-induced NAFLD mice. The expression level of enzymes involved in the synthesis and oxidation of fatty acids, acetyl-coA carboxylase and CYP2E1, were clearly reduced by MIT treatment. Reactive oxygen species (ROS) production and subsequent liver damage were effectively reduced by MIT treatment. Conclusion: We suggest that MIT is a potent herbal formula that can be used for the prevention and treatment of obesity-related NAFLD via regulating the levels of serum glucose and free fatty acids, inflammation, lipid accumulation, and ROS-mediated liver damage.
Gaseous by-products from the TiO₂ Photocatalytic Oxidation of Benzene
Sang Wook Han,Jin Hong Lee,Jin Seog Kim,Sang Hyub Oh,Young Kwon Park,Hyun Ook Kim 대한환경공학회 2008 Environmental Engineering Research Vol.13 No.1
Photocatalytic oxidations of benzene gas using the closed system (batch reactor) were induced to determine its by-products and investigate the effect of humidity and oxygen concentration on their generation. The study was able to identify 11 gaseous by-products: 2-methylpropene, acetaldehyde, acetone, pentane, methylcyclobutane, methylcyclopentane, cyclohexane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, and hexane. All the by-products were saturated hydrocarbons, which are less toxic than benzene and were probably formed through hydrogenation reaction on the photocatalytic surface. The photocatalytic oxidation of benzene under higher humidity produced less by-products. However, the amount of acetone released increased with higher humidity and oxygen concentration.
Kim, Jin-Hyoung,Kim, So-Yoen,Jang, Seol,Yi, Seungjun,Cho, Dae Won,Son, Ho-Jin,Kang, Sang Ook American Chemical Society 2019 Inorganic Chemistry Vol.58 No.23
<P>Incorporation of an electron-withdrawing −SO<SUB>2</SUB>CF<SUB>3</SUB> substituent to cyclometalating C^N-phenylpyridine (ppy) ligand resulted in an expected blue-shifted phosphorescence in the corresponding homoleptic <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> complex, showing the emission of λ<SUB>em</SUB> = 464 nm at 300 K. One of its heteroleptic derivatives, modified by a pyrazolyl borate LX ligand, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, exhibited further blue-shifted phosphorescence of λ<SUB>em</SUB> = 460 nm at 300 K. Cyclic voltammograms (CVs) and density-functional theory (DFT) calculations supported the efficacy of the electron-withdrawing capability of the SO<SUB>2</SUB>CF<SUB>3</SUB> substituent lowering HOMO energy and obtained widened bandgaps and resumed blue emissions for all of the iridium complexes studied. The homoleptic complexes of both substituents, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> and <B>Ir(ppySF)</B><SUB><B>3</B></SUB>, reached the higher quantum yields (<I>Φ</I><SUB>PL</SUB>) of (0.89 and 0.72), respectively. Similarly, emission quantum yields (<I>Φ</I><SUB>PL</SUB>) of the heteroleptic derivatives were reported to be (0.75, 0.83, and 0.87) for <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(acac)</B>, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, and <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(pic)</B>, respectively. Emission kinetics support the enhanced quantum efficiency when <I>k</I><SUB>r</SUB> and <I>k</I><SUB>nr</SUB> values are compared between <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB> and <B>Ir(ppySF)</B><SUB><B>3</B></SUB>, and both values favorably contribute to attaining a higher quantum efficiency for <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>3</B></SUB>. Among solution-processed multilayered devices having an ITO/PEDOT:PSS/TCTA:Ir dopant (10:1, <I>w</I>/<I>w</I>)/TmPyPB/Liq/Al structure, a heteroleptic dopant, <B>Ir(ppySCF</B><SUB><B>3</B></SUB><B>)</B><SUB><B>2</B></SUB><B>(bor)</B>, exhibited better device performance, reporting an external quantum efficiency (EQE) of 1.14%, current efficiency (CE) of 2.31 cd A<SUP>-1</SUP>, and power efficiency (PE) of 1.21 lm W<SUP>-1</SUP>, together with blue chromaticity of CIE<SUB>x,y</SUB> = (0.16, 0.32).</P><P>Blue phosphorescence of Ir(III) complexes can be tuned with the introducing of strong electron withdrawing substituents and the variation in the ancillary ligands.</P> [FIG OMISSION]</BR>
Kim, Jo-Eun,Shin, Jae-Myung,Oh, Sung-Ook,Yi, Won-Jin,Heo, Min-Suk,Lee, Sam-Sun,Choi, Soon-Chul,Huh, Kyung-Hoe Korean Academy of Oral and Maxillofacial Radiology 2013 Imaging Science in Dentistry Vol.43 No.4
Purpose: This study was performed to analyze human maxillary and mandibular trabecular bone using the data acquired from micro-computed tomography (micro-CT), and to characterize the site-specific microstructures of trabeculae. Materials and Methods: Sixty-nine cylindrical bone specimens were prepared from the mandible and maxilla. They were divided into 5 groups by region: the anterior maxilla, posterior maxilla, anterior mandible, posterior mandible, and mandibular condyle. After the specimens were scanned using a micro-CT system, three-dimensional microstructural parameters such as the percent bone volume, bone specific surface, trabecular thickness, trabecular separation, trabecular number, structure model index, and degrees of anisotropy were analyzed. Results: Among the regions other than the condylar area, the anterior mandibular region showed the highest trabecular thickness and the lowest value for the bone specific surface. On the other hand, the posterior maxilla region showed the lowest trabecular thickness and the highest value for the bone specific surface. The degree of anisotropy was lowest at the anterior mandible. The condyle showed thinner trabeculae with a more anisotropic arrangement than the other mandibular regions. Conclusion: There were microstructural differences between the regions of the maxilla and mandible. These results suggested that different mechanisms of external force might exist at each site.
Kim, Min-Ook,Lee, Kyounghoon,Na, Hyungjoo,Kwon, Dae-Sung,Choi, Jungwook,Lee, Jae-Ik,Baek, Dae-Hyun,Kim, Jongbaeg Elsevier 2014 Sensors and actuators. B Chemical Vol.197 No.-
A highly sensitive cantilever type chemo-mechanical hydrogen sensor with a novel sensing mechanism that can detect changes in contact resistance in self-adjusted carbon nanotube (CNT) arrays is described. The fabricated sensor is fully batch-fabricated on a silicon-on-insulator (SOI) wafer and is composed of two facing sets of CNT arrays, situated between a Pd-coated micro-cantilever, that serve as the electrode and counter-electrode. When the sensor is exposed to various concentrations of hydrogen at room temperature, resistance is decreased as the cantilever deforms and increases inter-CNT contact. Turning off the hydrogen re-shrinks the Pd, restoring the original cantilever position and recovering the initial resistance. The sensor can detect hydrogen diluted in nitrogen at concentrations of up to 4% and has an average response as high as -1.22% to a 0.1% concentration of hydrogen in air, which is the minimum detection limit. This sensitivity, which is much higher than in previously reported cantilever-type resistive chemo-mechanical hydrogen sensors, can be attributed to the novel sensing mechanism in which the narrow-gap between CNT arrays comprise the sensing component. (C) 2014 Elsevier B.V. All rights reserved.