A new K-band push-push VCO using a miniaturized hairpin resonator

Lee, Hyun-Wook,Yoon, Ki-Cheol,Nam, Hee,Eo, Yun-Seong,Lee, Jong-Chul Wiley Subscription Services, Inc., A Wiley Company 2010 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.52 No.3

<P>In this article, a K-band push-push Voltage Controlled Oscillator (VCO) is presented using a miniaturized hairpin resonator (MHR) with a higher loaded quality factor and the reduced circuit area within 50% compared to the conventional one at 9.2 GHz.The MHR combined with the GaAs MESFET varactor shows a tuning range of 140 MHz, and this voltage tunable MHR is used to compose a push-push VCO. It provides the frequency tuning range of 71 MHz with flatness of +0.13 dB, which is increased by 31 MHz compared to the conventional VCO. The voltage controlled push-push oscillator based on the series feedback topology is implemented on 0.54 mm-thick Teflon substrate with a dielectric constant of 2.54. The measurement shows the output power of 1.18 dBm, the fundamental signal power suppression of −33 dBc, and phase noise performance of −86.78 dBc/Hz at 100 kHz offset. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 699–701, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25007</P>

A broadband linearization method using a novel opto-electrical predistorter for radio-over-fiber systems

Moon, Yon-Tae,Choi, Woon-Kyung,Choi, Young-Wan Wiley Subscription Services, Inc., A Wiley Company 2010 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.52 No.7

<P>A broadband linearization method with a novel opto-electrical predistorter was experimentally demonstrated. With the proposed method, the third-order intermodulation distortion was simultaneously enhanced by more than 10 dB for 510 MHz ranges and by 24 dB at 2.2 GHz without any change in electrical circuitry. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1638–1640, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25240</P>

On triple Veronese embeddings of \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}<tex> $\mathbb {P}^n$</tex>\end{document}<img src='/wiley-blackwell_img/equation/tex2gif-ueqn-1.gif' alt='equation image'> in the Grassmannians

WILEY‐VCH Verlag 2011 Mathematische Nachrichten Vol.284 No.11

<P><B>Abstract</B></P><P>We classify all the embeddings of \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}<TEX>$\mathbb {P}_n$</TEX>\end{document}<IMG src='/wiley-blackwell_img/equation/tex2gif-ueqn-2.gif' alt ='equation image'/> in a Grassmannian <I>Gr</I>(1, <I>N</I>) such that the composition with the Plücker embedding is given by a linear system of cubics on \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}<TEX>$\mathbb {P}_n$</TEX>\end{document}<IMG src='/wiley-blackwell_img/equation/tex2gif-ueqn-3.gif' alt ='equation image'/>. As a direct corollary, we prove that every vector bundle giving such an embedding, splits if <I>n</I> ⩾ 3. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim</P>

Analog predistortion linearization of Doherty power amplifiers using bandwidth reduction of error signal

Lee, Yong-Sub,Lee, Mun-Woo,Kam, Sang-Ho,Jeong, Yoon-Ha Wiley Subscription Services, Inc., A Wiley Company 2010 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.52 No.6

<P>This article represents analog predistortion linearization of Doherty power amplifier (DPA) using bandwidth reduction of error signal. To verify our methods, two DPAs are implemented using a push-pull GaN HEMT and a push-pull Si LDMOS at 2.14 GHz and tested using the memory-compensated analog predistorter with transistor-based error generators and three-branch nonlinear paths. From the measured four-carrier WCDMA results, the proposed analog predistortion DPAs show the significant linearity improvement. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1313–1316, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25190</P>

Synthesis of the Tetraketide Lactones from the Pikromycin Biosynthetic Pathway

Oh, Hong-Se,Yun, Ji-Suk,Nah, Ki-Hyun,Kang, Han-Young,Sherman, David H. WILEY-VCH Verlag 2007 European journal of organic chemistry Vol.2007 No.20

<P>Synthesis of tetraketide lactones 2 and 3, which are likely to be produced by a model pikromycin polyketide synthase (PKS), has been investigated. The tetraketide lactones with six-membered rings, 2a and 2b, were synthesized successfully by the asymmetric aldol reaction, allylation, and the Reformatsky reaction. The attempted synthesis of tetraketide lactones with eight-membered rings, 3a and 3b, led to the formation of the compounds 2a and 2b. The synthesis of another tetraketide lactone compounds 35 was attempted with the hope that introducing an additional methyl group would lead to a change in thermodynamic stability. However, it produced the corresponding tetraketide lactone 34 with a six-membered ring. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/1434193X-2007-2007-20-EJOC200700254-fig000.gif' alt='wiley_img/1434193X-2007-2007-20-EJOC200700254-fig000'> </P>

Ruthenium-Catalyzed, One-Pot Alcohol Oxidation–Wittig Reaction Producing α,β-Unsaturated Esters

Lee, Eun Young,Kim, Youngkwon,Lee, Jae Sung,Park, Jaiwook WILEY-VCH Verlag 2009 EUROPEAN JOURNAL OF ORGANIC CHEMISTRY Vol.2009 No.18

<P>By a one-pot process, α,β-unsaturated esters were synthesized in high yield through the Ru-catalyzed oxidation of primary alcohols and the coupling of the resulting aldehydes and stabilized Wittig reagents. The ruthenium catalyst is composed of ruthenium nanoparticles embedded in aluminum oxyhydroxide and can be recovered simply by filtration or decantation.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)</P> <B>Graphic Abstract</B> <P>By a one-pot process, α,β-unsaturated esters were synthesized in high yield through the Ru-catalyzed oxidation of primary alcohols and the coupling of the resulting aldehydes and stabilized Wittig reagents. Theruthenium catalyst is composed of ruthenium nanoparticles embedded in aluminum oxyhydroxide and can be recovered simply by filtration or decantation. <img src='wiley_img/1434193X-2009-2009-18-EJOC200900274-fig000.gif' alt='wiley_img/1434193X-2009-2009-18-EJOC200900274-fig000'> </P>

Dinuclear Metallocenes with a Modulated Biphenylene Bridge for Olefin Polymerization

Kim, Seong Kyun,Kim, Hwa Kyu,Lee, Min Hyung,Yoon, Seung Woong,Han, Yonggyu,Park, Sungjin,Lee, Junseong,Do, Youngkyu WILEY-VCH Verlag 2007 European journal of inorganic chemistry Vol. No.

<P>Dinuclear group 4 metallocene catalysts linked by a biphenylene or 1,2-diphenylethylene bridge, namely [4,4′-(C<SUB>5</SUB>Me<SUB>4</SUB>)<SUB>2</SUB>(C<SUB>6</SUB>H<SUB>4</SUB>)<SUB>2</SUB>][CpZrCl<SUB>2</SUB>]<SUB>2</SUB> (2a), [p-(C<SUB>5</SUB>Me<SUB>4</SUB>)C<SUB>6</SUB>H<SUB>4</SUB>CH<SUB>2</SUB>]<SUB>2</SUB>[CpZrCl<SUB>2</SUB>]<SUB>2</SUB> (2b), [p-(3,4-Me<SUB>2</SUB>C<SUB>5</SUB>H<SUB>2</SUB>)C<SUB>6</SUB>H<SUB>4</SUB>CH<SUB>2</SUB>]<SUB>2</SUB>[CpZrCl<SUB>2</SUB>]<SUB>2</SUB> (2c), [(C<SUB>5</SUB>Me<SUB>4</SUB>)<SUB>2</SUB>(C<SUB>6</SUB>H<SUB>4</SUB>)<SUB>2</SUB>][TiCl<SUB>3</SUB>]<SUB>2</SUB> (3a), [p-(C<SUB>5</SUB>Me<SUB>4</SUB>)C<SUB>6</SUB>H<SUB>4</SUB>CH<SUB>2</SUB>]<SUB>2</SUB>[TiCl<SUB>3</SUB>]<SUB>2</SUB> (3b), and [p-(3,4-Me<SUB>2</SUB>C<SUB>5</SUB>H<SUB>2</SUB>)C<SUB>6</SUB>H<SUB>4</SUB>CH<SUB>2</SUB>]<SUB>2</SUB>[TiCl<SUB>3</SUB>]<SUB>2</SUB> (3c), have been prepared and the crystal structures of 2b and 3b determined by X-ray diffraction methods. The crystal structures reveal that these complexes consist of two equivalent metal units inverted with respect to the center of the bridge. All the complexes were tested for the polymerization of ethylene and styrene in the presence of methylaluminoxane (MAO), and direct comparisons of their catalytic properties with those of the corresponding mononuclear analogues [(PhC<SUB>5</SUB>Me<SUB>4</SUB>)CpZrCl<SUB>2</SUB>] (4a), [(p-TolC<SUB>5</SUB>Me<SUB>4</SUB>)CpZrCl<SUB>2</SUB>] (4b), [(1-p-Tol-3,4-Me<SUB>2</SUB>C<SUB>5</SUB>H<SUB>2</SUB>)CpZrCl<SUB>2</SUB>] (4c), [(PhC<SUB>5</SUB>Me<SUB>4</SUB>)TiCl<SUB>3</SUB>] (5a), [(p-TolC<SUB>5</SUB>Me<SUB>4</SUB>)TiCl<SUB>3</SUB>] (5b), and [(1-p-Tol-3,4-Me<SUB>2</SUB>C<SUB>5</SUB>H<SUB>2</SUB>)TiCl<SUB>3</SUB>] (5c) were performed. The dinuclear zirconocenes show a high activity in ethylene polymerization comparable with those of the corresponding mononuclear catalysts and give an increased molecular weight of polyethylene. The dinuclear half-sandwich titanocenes exhibit similar or slightly lower activity and molecular weight in styrene polymerization compared with their mononuclear analogues. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/14341948-2007-2007-4-EJIC200600833-fig000.gif' alt='wiley_img/14341948-2007-2007-4-EJIC200600833-fig000'> </P>

Preparation of Mesoporous Silica and Carbon Materials with Multilength-Scale Pores and Hydrogen Sorption Application

Kwon, Tae-Hwan,Jung, Suhyun,Kim, Hee-Jin,Park, Seongsoon,Kim, Sung-Jin,Huh, Seong WILEY-VCH Verlag 2009 European journal of inorganic chemistry Vol.2009 No.19

<P>A facile method was developed for the preparation of bimodal mesoporous siliceous materials with nanostructured pores in which a cationic organic template, n-hexadecyltrimethylammonium hydroxide, was employed as a base catalyst as well as a mesopore structure-directing agent during the slow condensation of tetraethoxysilane. It was possible to alter the pore orientations of smaller pores by adding neutral auxiliary templates such as Brij76 and P123. A series of biomodal mesoporous carbons was also obtained from the bimodal mesoporous silica materials through a nanocasting process. The resulting bimodal mesoporous carbons exhibited decent hydrogen uptake values at 77 K. The maximum hydrogen uptake was 1.33 wt.-% for the sample having the narrowest pores, while keeping a relatively large pore volume. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)</P> <B>Graphic Abstract</B> <P>A simple preparation method of various bimodal mesoporous silica and carbon materials with interesting nanostructures was developed. Their hydrogen uptake abilitieswere investigated at 77 K. The sample with small pores and a large pore volume showed enhanced hydrogen sorption ability. <img src='wiley_img/14341948-2009-2009-19-EJIC200900153-fig000.gif' alt='wiley_img/14341948-2009-2009-19-EJIC200900153-fig000'> </P>

Ring-Closing Metathesis Dimerizations of Enynes and Deprotections of Propargyl Ethers Mediated by Carbene Ruthenium Complexes

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>

A Novel Series of Heteropolynuclear Metallomesogens: Organopalladium Complexes with Ferrocenophane-Containing Ligands

Kadkin, Oleg N.,An, Jaein,Han, Haksoo,Galyametdinov, Yuri G. WILEY-VCH Verlag 2008 European journal of inorganic chemistry Vol.2008 No.10

<P>Ferrocenophane-containing (Fcph) Schiff's bases p-C<SUB>12</SUB>H<SUB>25</SUB>O(C<SUB>6</SUB>H<SUB>4</SUB>)CH=N(C<SUB>6</SUB>H<SUB>4</SUB>)Fcph (L<SUP>A</SUP>H) and p-C<SUB>12</SUB>H<SUB>25</SUB>O(C<SUB>6</SUB>H<SUB>4</SUB>)COO(C<SUB>6</SUB>H<SUB>4</SUB>)CH=N(C<SUB>6</SUB>H<SUB>4</SUB>)Fcph (L<SUP>B</SUP>H) react with palladium(II) acetate to form μ-acetato- and chloro-bridged dimeric organopalladium complexes. By exchanging acetato-groups with the chloride anions, μ-chloro-bridged heteropolynuclear dimers are obtained that show thermotropic smectic A phases over a temperature range of 198 to 260 °C. The complexes [PdClL<SUP>A</SUP>]<SUB>2</SUB> and [PdClL<SUP>B</SUP>]<SUB>2</SUB> can be transformed into a variety of mixed-ligand Pd<SUP>II</SUP> complexes by treatment with salicylaldimine p-C<SUB>12</SUB>H<SUB>25</SUB>O(C<SUB>6</SUB>H<SUB>4</SUB>)COO(C<SUB>6</SUB>H<SUB>3</SUB>)(OH)CH=N(C<SUB>6</SUB>H<SUB>4</SUB>)Fcph (L<SUP>C</SUP>H) and β-aminovinyl ketone p-C<SUB>12</SUB>H<SUB>25</SUB>O(C<SUB>6</SUB>H<SUB>4</SUB>)COCH=CHNH(C<SUB>6</SUB>H<SUB>4</SUB>)Fcph (L<SUP>D</SUP>H). The obtained mixed-ligand heterometallic complexes [PdL<SUP>A</SUP>L<SUP>C</SUP>], [PdL<SUP>B</SUP>L<SUP>C</SUP>], [PdL<SUP>A</SUP>L<SUP>D</SUP>] and [PdL<SUP>B</SUP>L<SUP>D</SUP>] exhibit enantiotropic, thermotropic nematic phases over a broad temperature range from 71 to 205 °C. The structures of the synthesized compounds were characterized by means of <SUP>1</SUP>H NMR, IR and UV spectroscopy, as well as elemental analysis. The liquid crystalline properties were studied by polarising optical microscopy and DSC. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)</P> <B>Graphic Abstract</B> <P>Liquid crystalline heteropolynuclear complexes based on palladium(II) chelates withvarious ferrocenophane-containing ligands were synthesized. <img src='wiley_img/14341948-2008-2008-10-EJIC200700750-fig000.gif' alt='wiley_img/14341948-2008-2008-10-EJIC200700750-fig000'> </P>