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Electrical transport properties of a single wall carbon nanotube network
Hwang, J. S.,Kim, H. T.,Kim, H. K.,Son, M. H.,Hwang, S. W.,Ahn, D. WILEY-VCH Verlag 2009 Physica Status Solidi. B Vol.246 No.4
<P>A single wall carbon nanotube (SWCNT) network is fabricated and its electronic transport properties are investigated. It shows a typical p-type field-effect-transistor (FET) behavior and nonlinearities in the source current-source bias characteristics. The network also exhibits incomplete turn-off and a small mobility. These characteristics are explained by the fact that the network is a mixture of metallic and semiconducting SWCNTs connecting with one another. Various cross junctions such as SWCNT (semiconducting)-SWCNT (semiconducting), SWCNT (semiconducting)-SWCNT (metallic) are the source of nonlinearities and the small mobility. Incomplete turn-off can be explained by the parallel conduction paths consisting of metallic SWCNTs which are insensitive to the gate bias. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Hahn, Dong-Woo,Byun, Dong-Min,Tae, Jinsung WILEY-VCH Verlag 2005 European journal of organic chemistry Vol.2005 No.1
<P>The ring-forming dimerizations of enynes were catalyzed by the first-generation carbene ruthenium complex, and the effects of the catalysts and ethylene gas were studied. The deprotection of propargyl ethers by the carbene ruthenium complexes is the first to be reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/1434193X-2005-2005-1-EJOC200400630-fig000.gif' alt='wiley_img/1434193X-2005-2005-1-EJOC200400630-fig000'> </P>
PMMA coated carbonyl iron microbeads and their magnetic characteristics
Kim, Min Su,Cho, Min Sung,Choi, Hyoung Jin WILEY-VCH Verlag 2007 Physica status solidi. PSS. A, Applications and ma Vol.204 No.12
<P>In order to improve the stability of magnetorheological (MR) fluid, we synthesized poly(methyl methacrylate) (PMMA) - encapsulated carbonyl iron (CI) particles by an in-situ dispersion polymerization method. In addition, PMMA shell was cross-linked by a cross-linking agent. The cross-linked PMMA is expected to be more effective than non-cross-linked PMMA, improving the physical properties. The synthesized CIPMMA composite particles were characterized by SEM, and VSM. Cross-linking of PMMA was also confirmed by measuring the FT-IR after etching process. Rheological properties of the PMMA-coated CI based MR fluid were measured via a rotational rheometer. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Park, S. Y.,Lee, Hyung Woo,Lee, Young Soo,Wang, D. F.,Lee, Y. P.,Rhee, J. Y. WILEY-VCH Verlag 2007 Physica status solidi. PSS. C, Current topics in s Vol.4 No.12
<P>Polycrystalline ZnO/La<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB> (LSMO) heterostructures were fabricated onto Si(100) substrates by magnetron sputtering. A rectifying behavior, as well as an enhanced magnetoresistance (MR) ratio (∼ 12%), was obtained in the heterostructure with respect to the LSMO single layer (a MR ratio ∼ 6%). The degradation of the rectifying behavior for the LSMO layer thinner than 20 nm is mainly due to the change in hole concentration. We suggest a possibility that the magneto-transport and the magneto-optical properties of manganites can be modified by the formation of this kind of heterostructure. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Yoo, Houng Sik,Yoon, Jung Hee,Kim, Jae Il,Koh, Eui Kwan,Hong, Chang Seop WILEY-VCH Verlag 2008 European journal of inorganic chemistry Vol.2008 No.20
<P>The reaction of Co<SUP>II</SUP> and 2,2′-dipyridyldisulfide (PySSPy) in the presence of azide produced a peculiar monomeric complex [Co<SUP>III</SUP>(PyS)(PyS-N-SPy)(N<SUB>3</SUB>)] (1). In this reaction, redox chemistry takes place, which is associated mainly with the oxidation of Co<SUP>II</SUP> to Co<SUP>III</SUP> and the reduction of PySSPy. During the reaction, the azide ion decomposes and donates a nitrogen atom to PySSPy. The crystal structure of 1 provides evidence that the unusual, N-inserted ligand PyS-N-SPy can be stabilized through coordination to the electropositive Co<SUP>III</SUP> ion. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)</P> <B>Graphic Abstract</B> <P>The reaction of Co<SUP>II</SUP> and 2,2′-dipyridyldisulfide (PySSPy) in the presence of azide produced a monomeric complex [Co<SUP>III</SUP>(PyS)(PyS-N-SPy)(N<SUB>3</SUB>)] (1), which was characterized by means of UV/Vis, X-ray crystallography, XPS, and cyclic voltammetry. The unusual, N-inserted ligand PyS-N-SPy can be stabilized through coordination to the electropositive Co<SUP>III</SUP> ion. <img src='wiley_img/14341948-2008-2008-20-EJIC200800439-fig000.gif' alt='wiley_img/14341948-2008-2008-20-EJIC200800439-fig000'> </P>
TMSOTf-Promoted Addition of Alkynes to Aldehydes: A Novel Synthesis of Chroman-4-ones
Park, Ji Yeon,Ullapu, Punna Reddy,Choo, Hyunah,Lee, Jae Kyun,Min, Sun-Joon,Pae, Ae Nim,Kim, Youseung,Baek, Du-Jong,Cho, Yong Seo WILEY-VCH Verlag 2008 EUROPEAN JOURNAL OF ORGANIC CHEMISTRY Vol.2008 No.32
<P>A novel synthetic method to prepare chalcones 2 and chroman-4-ones 3 by TMSOTf-promoted addition of alkynes 1 to various aldehydes has been developed. The ratios of chalcones 2, chroman-4-ones 3 and hydrated products 4 varied depending upon the substituents R (nBu, phenyl, H and TMS) on the alkynes 1. We also describe the transformation of the chalcones 2 to the corresponding chroman-4-ones 3 under basic conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)</P> <B>Graphic Abstract</B> <P>A novel synthetic method to prepare chalcones and chroman-4-ones by TMSOTf-promoted addition of alkynes to various aldehydes has been developed. The ratios of chalcones, chroman-4-ones and hydratedproducts vary depending upon the substituents on the alkynes. We also describe the transformation of the chalcones to the corresponding chroman-4-ones under basic conditions. <img src='wiley_img/1434193X-2008-2008-32-EJOC200800782-fig000.gif' alt='wiley_img/1434193X-2008-2008-32-EJOC200800782-fig000'> </P>
Choi, Kang Ryong,Kouh, Taejoon,Kim, Sam Jin,Kim, Chul Sung WILEY-VCH Verlag 2007 Physica status solidi. PSS. B, Basic solid state p Vol.244 No.12
<P>In order to elucidate the role of Cr ions in MCr<SUB>2</SUB>O<SUB>4</SUB>(M = Co, Zn) exhibiting geometrically frustration and multiferroic property, we have substituted a small amount of Fe ions for Cr sites and investigated the magnetic behavior of Fe ions with Mössbauer spectroscopy. The crystal structure was found to be single-phase cubic spinel with space group of Fd3m. The lattice constants a<SUB>0</SUB> and the internal structural parameter (x) of the oxygen were determined to be 8.340, 8.331 Å and 0.261 and 0.260, respectively. The Mössbauer absorption spectra at 4.2 K show that the well-developed two sextets are superposed with small difference of hyperfine fields(H<SUB>hf</SUB>). The hyperfine fields of CoCr<SUB>1.98</SUB><SUP>57</SUP>Fe<SUB>0.02</SUB>O<SUB>4 </SUB>and ZnCr<SUB>1.98</SUB><SUP>57</SUP>Fe<SUB>0.02</SUB>O<SUB>4</SUB> were determined to be 490 ∼ 480 kOe and 460 ∼ 450 kOe, respectively. Isomer shift values (δ) of the two sextets are found to be 0.33 ∼ 0.35 mm/s relative to those of Fe metal, which are consistent with the high spin Fe<SUP>3+</SUP> charge state. From the results of Mössbauer measurement, it is suggested that Cr<SUP>3+</SUP> ions have two different magnetic sites, and there is a correlation between hyperfine fields and degree of magnetic geometrical frustration. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Magnetic properties of Mn-doped Bi<sub>2</sub>Te<sub>3</sub> and Sb<sub>2</sub>Te<sub>3</sub>
Choi, Jeongyong,Choi, Sungyoul,Choi, Jiyoun,Park, Yongsup,Park, Hyun-Min,Lee, Hee-Woong,Woo, Byung-Chul,Cho, Sunglae WILEY-VCH Verlag 2004 Physica status solidi. PSS. B, Basic solid state p Vol.241 No.7
<P>We have fabricated Mn-doped Bi<SUB>2</SUB>Te<SUB>3</SUB> and Sb<SUB>2</SUB>Te<SUB>3</SUB> single crystals by the vertical gradient solidification method. The compositions and crystal structures of Bi<SUB>2−x</SUB>Mn<SUB>x</SUB>Te<SUB>3</SUB> and Sb<SUB>2−x</SUB>Mn<SUB>x</SUB>Te<SUB>3</SUB> were determined using Electron Probe Micro-Analyzer (EPMA) and powder X-ray diffraction (XRD) patterns, respectively. Both crystal structures were rhombohedral with smaller lattice constants because of the smaller atomic radius of Mn than those of Bi and Sb. Based on the magnetization measurements, Mn-doped Bi<SUB>2</SUB>Te<SUB>3</SUB> and Sb<SUB>2</SUB>Te<SUB>3</SUB> compounds have ferromagnetic ordering at T<SUB>C</SUB> = 10 and 17 K, respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Le, Khai Q.,Kim, Sangin WILEY-VCH Verlag 2008 Physica status solidi. PSS. A, Applications and ma Vol.205 No.2
<P>In this paper, a theoretical model for the cross-plane thermal conductivity of layered quantum semiconductor structures is presented. This model is used to evaluate the cross-plane thermal conductivity of the active region in GaInAs/AlInAs-based quantum cascade (QC) lasers. We take into account the temperature dependent thermal conductivity of the layers. By including their interface thermal resistance and scattering processes via the multilayer quantum structure, we predict a decrease by an order of magnitude of the lattice thermal conductivity of the active region in GaInAs/AlInAs-based QC lasers. We computed that the cross-plane thermal conductivity of a InGaAs/AlInAs-based QC laser active region at low temperature from 80 K to 130 K is in the range of 0.5–0.7 W/(m K), whilst the average experimental value obtained by Lops et al. [13] is 0.6 W/(m K). In addition, using the result as input, we present a numerical investigation into the facet temperature profile in this laser during continuous-wave operation using a finite-element method. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
WILEY-VCH Verlag 2009 EUROPEAN JOURNAL OF ORGANIC CHEMISTRY Vol.2009 No.16
<P>Tandem transformations represent one of the most efficient methods for the synthesis of complex molecules from readily available starting materials, as evidenced by the intense research activity and the plethora of literature published in this area. This review highlights recent developments of rhodium(I)-catalyzed tandem transformations with organoboron compounds involving the formation of multiple carbon–carbon bonds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)</P> <B>Graphic Abstract</B> <P>This review provides an overview of recent developments of rhodium(I)-catalyzed tandem transformations with organoborons involving the formation of multiple carbon–carbon bonds. These processes are powerful and straightforward methods for the synthesis of complex molecules including both acyclic and cyclic compounds. <img src='wiley_img/1434193X-2009-2009-16-EJOC200900001-fig000.gif' alt='wiley_img/1434193X-2009-2009-16-EJOC200900001-fig000'> </P>