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Selected AbstractsNumerical Analysis and Simulation Analysis for Space-Time DataCONTRIBUTIONS TO PLASMA PHYSICS, Issue 10 2006M. A. Hassouba Abstract Spatio temporal dynamics of the positive column of a dc neon glow discharge is studied and investigated experimentally and theoretically. Spatio temporal analysis by means of biorthogonal decomposition method (BOD) gives insights into the mechanism of irregularity and can be employed for characterization of spatio- temporal complexity. In the weak nonlinear region, the wave dynamics is approximated by an amplitude equation of the Ginzburg-Landau equation (CGLE) with complex coefficients and an additional integral term based on a fluid model. In the present work we deal with irregular spatio-temporal data. A comparison between the numerical analysis of the experimental data and simulation results are studied. A good agreement between the dynamical behaviour for experimental space-time data and theoretical simulation space-time results was obtained. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] State criterion of wind turbine generator operation using tower shadow effect (Part 2)ELECTRICAL ENGINEERING IN JAPAN, Issue 1 2008Tadashi Naitoh Abstract In order to obtain wind energy effectively, the pole-change-type induction generators are used as the wind turbine generators. Otherwise, the pole-change-type induction generator causes the voltage dips at pole changing time. To maintain the power quality, it is important to know the state change of the generator operation. Therefore, the authors have studied a state criterion of generator using the tower shadow effect, which is the active power oscillation caused by a rotation torque drop when the tower and the turbine blade overlap each other. In this paper, an improved identification method of oscillation frequency, which is the criterion of wind turbine generator operation, is proposed. The proposed method is applied to measured data and good results are obtained. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 25,31, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20395 [source] Variation in toxin compositions of two harmful raphidophytes, Chattonella antiqua and Chattonella marina, at different salinitiesENVIRONMENTAL TOXICOLOGY, Issue 2 2002Shahroz Mahean Haque Abstract Toxin compositions of the two species of raphidophytes, Chattonella antiqua (Hada) Ono and Chattonella marina (Subrahmanyan) Hara et Chihara, were investigated at different salinities under laboratory conditions. C. antiqua contained toxin components CaTx-I, CaTx-II, CaTx-III, and CaTx-IV, which corresponded to brevetoxin components PbTx-1, PbTx-2, PbTx-3, and oxidized PbTx-2. Similarly, C. marina included CmTx-I, CmTx-II, CmTx-III, and CmTx-IV corresponding to PbTx-2, PbTx-9, PbTx-3, and oxidized PbTx-2. Toxin yields in both species varied markedly with a change in salinity concentration. In C. antiqua CaTx-I, CaTx-II, and CaTx-III peaked at 25 P.P.t. with yields of 0.99, 0.42, and 2.90 pg/cell, but the highest yield (2.35 pg/cell) of CaTx-IV was attained at 30 P.P.t. The yields of all CaTx components decreased sharply at salinities exceeding 30 P.P.t. On the other hand, C. marina yielded higher proportions of CmTx-I (0.55 pg/cell) and CmTx-III (2.50 pg/cell) at 25 P.P.t. However, CmTx-IV was present in its highest amount (1.65 pg/cell) at 30 P.P.t., as seen in C. antiqua. A small amount of CmTx-II was also detected at 20 P.P.t.,35 P.P.t. Both species showed the highest ichthyotoxicities at 25 P.P.t., at which the maximum cell division rate was obtained. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 113,118, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10039 [source] Strong Evidence for an Unprecedented Borderline Case of Dissociation and Cycloaddition in Open-Shell 1,3-Dipole Chemistry: Transient Nitrilium Phosphane-Ylide Complex Radical CationsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2009Holger Helten Abstract The reaction of 3-ferrocenyl-substituted 2H -azaphosphirene complexes 1a,c in the presence of substoichiometric amounts of ferrocenium hexafluorophosphate yields 3,5-diferrocenyl-substituted 2H -1,4,2-diazaphosphole complexes 3a,c and difluoro(organo)phosphane complexes 4a,c. The reaction of 1a,c and [FcH]PF6 with cyanoferrocene yields 3a,c in a straightforward way. The molecular structures of 3a,c were unambiguously identified by multinuclear NMR spectroscopic experiments, mass spectrometry, and single-crystal X-ray diffraction studies. DFT calculations on model complexes 1d,m and 3d,m reveal a close similarity of Mo and W complexes (vs. Cr) and a strong influence of the ferrocenyl substituent on the geometry, spin, and charge distribution of reactive intermediates and the reaction course. Strong support for the assumption of a dissociation,cycloaddition reaction sequence leading to 3 and thus a surprising "cannibalistic" reaction was obtained.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Bulky Pyrazolate-Based Compartmental Ligand Scaffolds: Encapsulation of an Edge-Sharing Cu6O2 Bitetrahedral Core,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 34 2008Anna Sachse Abstract Upon reaction with Cu(OAc)2·H2O, pyrazole-based ligands with two appended imine chelate arms in the 3- and 5-positions of the pyrazole and bulky substituents at the imine-N yield Cu6 complexes [L2Cu6(,-OAc)6(,4 -O)2] (1a,b). They feature an unusual {Cu6(,4 -O)2}-bitetrahedral core, only the second example of this structural motif. ESI mass spectrometric and UV/Vis data confirm that the Cu6 complexes stay intact in solution, and magnetic and high-field EPR measurements reveal an S = 0 ground state with the first excited triplet at ,E , 95 cm,1. Although the new hexanuclear systems are too complex for deriving all individual exchange constants from powder susceptibility data, a rough idea of the complete energy level spectrum could be obtained.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] A Series of Red-Light-Emitting Ionic Iridium Complexes: Structures, Excited State Properties, and Application in Electroluminescent DevicesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2008Shu-Juan Liu Abstract A series of ionic diiminoiridium complexes [Ir(piq-C,N)2(L-N,N)](PF6) were prepared, where piq-C,N is 1-phenylisoquinolinato and L-N,N are bidentate N-coordinating ligands: 2,2,-bipyridine (bpy), 4,4,-dimethyl-2,2,-bipyridine (mbpym), 5,5,-bis(thiopen-2-yl)-2,2,-bipyridine (tbpyt), and 5,5,-bis(9,9-dioctylfluoren-2-yl)-2,2,-bipyridine (FbpyF). X-ray diffraction studies of [Ir(piq)2(mbpym)](PF6) revealed that the iridium center adopts a distorted octahedral geometry. All complexes exhibited intense and long-lived emission at room temperature. The substituents on the 2,2,-bipyridine moieties influence the photophysical and electrochemical properties. The excited states were investigated through theoretical calculations together with photophysical and electrochemical properties. It was found that the excited state of the [Ir(piq)2(FbpyF)](PF6) complex can be assigned to a mixed character of 3LC (,N,N,,*N,N), 3MLCT, 3LLCT (,C,N,,*N,N), and 3LC (,C,N,,*C,N). In addition, the alkylfluorene-substituted complex, [Ir(piq)2(FbpyF)](PF6), hadrelatively high quantum efficiency and good film-forming ability, and it was expected to be a good candidate for lighting and display applications. A nondoped, single-layer device that incorporates this complex as a light-emitting layer was fabricated and red phosphorescence was obtained.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Columnar Mesomorphism in Hexacatenar Tetrahedral (2,2,-Bipyridine)zinc Complexes and Homologous Palladium DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2005Giovanna Barberio Abstract The synthesis and characterisation of novel liquid crystals which display columnar mesomorphism induced upon complexation of a series of nonmesomorphic hexacatenar 4,4,-disubstituted 2,2,-bipyridines (Ln) are reported. The introduction of different metal centres (Zn, Pd) causes the appearance of mesomorphism in all complexes regardless of the geometry around the metal ion. We therefore report the first examples of mesomorphism in tetrahedral zinc derivatives. The nature of the columnar phases is related to the self-assembly of the half-disc shaped [LnMCl2] (M = Zn, Pd) complexes into full disc-shaped supramolecules. The molecular organisation in the mesophase is mainly driven by intermolecular attractive interactions, as shown by the crystal structure of the model compound [LPdCl2]. Preliminary measurements of photoconductivity have been performed on samples of [LnMCl2] complexes doped with C60 to increase absorption. Promising results were obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Self-Organization of Dipolar 4,4,-Disubstituted 2,2,-Bipyridine Metal Complexes into Luminescent Lamellar Liquid CrystalsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2003Daniela Pucci Abstract Mononuclear cis -dichloro complexes, [LnMCl2], with different metal centres (PtII, NiII, and ZnII) and a series of palladium and platinum derivatives, [L2MX2], in which chloride groups are replaced with iodide, bromide, and azide ligands, have been synthesized from 4,4,-disubstituted-2,2,-bipyridines. Upon complexation of these non-mesogenic ligands, the peculiar structural arrangement, characterized by intermolecular associations of the new derivatives, induces mesomorphism in most [L2MX2] complexes, confirming the importance of coordination chemistry in metal-mediated formation of liquid crystals. Single crystal X-ray structures have been determined for dihexadecyl 2,2,-bipyridyl-4,4,-dicarboxylatopalladium and -zinc dichloride derivatives. Both the metal centres and the ancillary ligands have been varied to use dipole coupling as a tool to control molecular architecture: thermal, as well as spectroscopic properties, depend strongly upon molecular dipolar interactions. Tunable red and blue emitters based on PdII and PtII, both in solution and in the solid state, have been obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Ruthenium-Catalyzed Allenyl Carbamate Formation from Propargyl Alcohols and IsocyanatesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2008Edgar Haak Abstract Ruthenium complexes of redox-coupled cyclopentadienone ligands catalyze the formation of allenyl carbamates from propargyl alcohols and isocyanates. This efficient and atom-economical process represents the first catalytic access to allenyl carbamates, compounds of high synthetic potential. The reaction needs an acidic co-catalyst and can be performed at room temperature. In addition, new (cyclopentadienone)iron and -ruthenium complexes were synthesized, and mechanistic aspects regarding catalytic transformations of propargyl systems with ruthenium catalysts are obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Reductive Coupling of Aromatic Aldehydes Promoted by an Aqueous TiCl3/tBuOOH System in Alcoholic CosolventsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2007Angelo Clerici Abstract The tert -butoxyl radical, generated by the aqueous TiIII/TBHP system, abstracts an H atom from alcoholic cosolvents (EtOH, iPrOH), leading to ,-hydroxyalkyl radicals thatreduce aromatic aldehydes to the corresponding 1,2-diols. The reactivities observed are explained by resonance stabilization of the ,-hydroxybenzyl radicals formed in the electron-transfer (ET) process. Good Hammett-type correlations are obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Highly Enantioselective and Catalytic Aryl Transfer Reaction Using Mixed Triarylbismuthane and Dialkylzinc ReagentsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2007Itaru Sato Abstract Highly enantioselective and catalytic aryl transfer reactions to aromatic aldehydes by using mixed triarylbismuthane and dimethylzinc reagents were studied. In the presence of a chiral ,-amino alcohol catalyst, chiral diarylmethanols with up to 97,% ee were obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] An Efficient Synthesis of 2-Bromo-3-hydroxy Esters by Reaction of Ketones with Ethyl Dibromoacetate Promoted by Samarium DiiodideEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2006José M. Concellón Abstract A simple and efficient samarium diiodide mediated synthesis of 2-bromo-3-hydroxy esters 1 by the reaction of a variety of ketones 2 with ethyl dibromoacetate (3) is described. The relative configuration of the major diastereoisomer obtained was established by NOESY experiments of the corresponding ,,,-epoxy esters 4 prepared from 1. Additionally, a mechanism is proposed to explain the results obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Novel Asymmetric Wittig Reaction: Synthesis of Chiral Allenic EstersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2004Teresa M. V. D. Pinho e Melo Abstract Wittig reactions between 10-(phenylsulfonyl)isobornyl (triphenylphosphoranylidene)acetates (1 and 6) and ketenes resulted in asymmetric induction, with the selective synthesis of allenes with axial chirality. Use of the (1R)-(,)-10-(phenylsulfonyl)isoborneol unit allows the synthesis of allenes with S configuration, whereas use of the (1S)-(+)-10-(phenylsulfonyl)isoborneol unit produces allenes with R configuration. The structure of (1R)-(,)-10-(phenylsulfonyl)isobornyl (S)-5,5-dimethylhexa-2,3-dienoate (2e) was determined by X-ray crystallography. Chirooptical studies of the allenic esters were carried out, confirming that two sets of enantiomeric derivatives were obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Vicarious Nucleophilic Substitution of (Chloroalkyl)oxazolines with Nitroarenes: Synthesis of (Nitrobenzyl)oxazolinesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2003Saverio Florio Abstract 2-Chloroalkyloxazolines 1a and 1b react with nitroarenes in the presence of tBuOK in DMSO to give, upon acidic quenching, substituted nitroaryloxazolines 2a, 2b, 3a, 9, 10, 11a,d, 12,19, and 21,22, probably by vicarious nucleophilic substitution (VNS). The reaction of 1a is poorly regioselective, while that of 1b is completely para regioselective, thus showing that the coupling is sterically controlled. Trapping of the carbanionic intermediate B of the VNS reaction with electrophiles furnished ,,,-disubstituted (nitrobenzyl)oxazolines 4,7. Attempts to trap B with PhCHO failed: the [(p -nitrophenyl)oxazolinyl]ethanol 8 was obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Flashing characteristics in a pipe downstream from a depressurizing tank and temperature fluctuation characteristics at a mixing tee junction with cold water injectionHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2003Koji Shiina Abstract The flashing characteristics in a pipe downstream from a depressurizing tank were experimentally and analytically investigated on the basis of the transient test and two-phase flow analysis. The following conclusions were obtained. (1) When the pressure margin of the pump inlet side and the distance to obtain an isothermal condition were sufficient, flashing phenomena did not occur in spite of the decreasing pressure. (2) When the ratio of the cold water injection flow rate to the hot water flow rate Mc/Mh increased, the peak distance of the water temperature fluctuation moved from L/D = 1 to 0, and the maximum water temperature fluctuation ratio was about 40% of the temperature difference between hot and cold water near the mixing tee junction. Because no problem occurred regarding the pipe material thermal fatigue, reliability of the mixing tee junction was assured. (3) Due to suppression of flashing phenomena of the mixing pipe system, the decision diagram on the flashing occurrence was obtained from the test and the analytical results, taking into consideration three factors: the depressurizing ratio in the tank; the cold water injection flow rate due to remaining subcooling; and the delay time of thermal mixing. The simplified analytical equation was used to decrease the cold water injection flow rate by the optimized pipe length between the mixing tee junction and the drain pump. The cold water injection flow rate was minimized when the pipe length was about 15 to 20 times the pipe inner diameter. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 411,429, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10096 [source] Synthesis of ,-fluoro-,-trifluoromethyl alka-2,4-dienesHETEROATOM CHEMISTRY, Issue 3 2007Yanchang Shen The palladium/copper(I) iodide cocatalyzed coupling reaction of (Z)-,-fluoro-,-trifluoromethylstannanes (1) with vinyl iodides (2) has been explored giving substituted ,-fluoro-,-trifluoromethyl dienes (3) in 33,95% yields. In studies we have conducted so far, a larger number of the configurations of the products remained unchanged (cases 3a, 3e,h), though in several cases (cases 3b,d) two configurations of the products were obtained. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:208,211, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20284 [source] Copolymerization of n -butylacrylate with methylmethacrylate by a novel photoinitiator, 1-(bromoacetyl)pyreneINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2007Anuradha Mishra The photopolymerization efficiency of pyrene (Py), 1-acetylpyrene (AP), and 1-(bromoacetyl)pyrene (BP) for copolymerization of n -butylacrylate (BA) with methylmethacrylate (MMA) was compared. A kinetic study of solution copolymerization in DMSO at 30 ± 0.2°C showed that the Py could not initiate copolymerization even after 20 h, whereas with AP as initiator, less than 1% conversion was observed. However, introduction of a Br in ,-methyl group of AP significantly enhanced the percent conversion. The kinetics and mechanism of copolymerization of BA with MMA using BP as photoinitiator have been studied in detail. The system follows nonideal kinetics (Rp,, [BP]0.67[BA]1[MMA]0.98), and degradative solvent transfer reasonably explains these kinetic nonidealities. The monomer reactivity ratios (MRRs) of MMA and BA have been estimated by the Finemann,Ross and Kelen,Tudos methods, by analyzing copolymer compositions determined by 1H-NMR spectra. The values of r1 (MMA) and r2 (BA) were found to be 2.17 and 0.44, respectively, which suggested the high concentration of alternating sequences in the random copolymers obtained. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 261,267, 2007 [source] Kinetics of oxidation of reducing sugars by catalytic amount of osmium(VIII) in presence of periodateINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 8 2004Rashmi Tripathi The kinetics of oxidation of some reducing sugars viz. glucose, galactose, fructose, maltose, and lactose by osmium(VIII) in presence of sodium metaperiodate in alkaline medium have been investigated. The reactions are zero order in periodate. The order of reaction in substrate and OH, decreases from unity to zero at higher [substrate] or [OH,], respectively. Rate of oxidation is proportional to [Osmium(VIII)]. Osmium(VIII) serves as an effective oxidant which oxidizes reducing sugars and itself reduces to osmium(VI). Role of IO4, is to regenerate osmium(VIII) from osmium(VI). An evidence for the complex formation between osmium(VIII) and reducing sugar has also been obtained. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:441,448, 2004. [source] Handling linguistic web information based on a multi-agent systemINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 5 2007Zheng Pei Much information over the Internet is expressed by natural languages. The management of linguistic information involves an operation of comparison and aggregation. Based on the Ordered Weighted Averaging (OWA) operator and modifying indexes of linguistic terms (their indexes are fuzzy numbers on [0,T] , R+), new linguistic aggregating methods are presented and their properties are discussed. Also, based on a multi-agent system and new linguistic aggregating methods, gathering linguistic information over the Internet is discussed. Moreover, by fixing the threshold ,, "soft filtering information" is proposed and better Web pages (or documents) that the user needs are obtained. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 435,453, 2007. [source] An accurate few-parameter ground state wave function for the lithium atomINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2009Nicolais L. Guevara Abstract A simple, seven-parameter trial function is proposed for a description of the ground state of the Lithium atom. It includes both spin functions. Inter-electronic distances appear in exponential form as well as in a pre-exponential factor, and the necessary energy matrix elements are evaluated by numerical integration in the space of the relative coordinates. Encouragingly accurate values of the energy and the cusp parameters as well as for some expectation values are obtained. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Discrete and continuum quantum states for the Kratzer oscillatorINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2002Adelio R. MatamalaArticle first published online: 2 JUL 200 Abstract Kratzer oscillator is a realistic zero-order model for describing the anharmonic ro-vibrational motion in diatomic molecules. Kratzer oscillator has an energy spectrum containing both discrete and continuum parts. Wavefunctions belonging to the continuum would be useful in the study of transitions to the continuum in molecular dissociation processes. In this article, bound and scattering wavefunctions of the Kratzer oscillator are reviewed and the bound,bound and the bound,free matrix elements are obtained. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 [source] A new equivalent circuit for inverters and its application for the determination of coupling matrix elements of narrow RF bandpass filtersINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 1 2010M. K. Haldar Abstract A new equivalent circuit for inverters is presented. Using this circuit, expression for the elements of the coupling matrix of narrow RF band pass filters is derived. The derivation is based on frequency independent coupling assumed in the synthesis of narrow RF band pass filters. Our expression is different from an earlier expression obtained using lumped circuit representations of different types of coupling and their analysis. It is shown that the earlier expression can be derived from our analysis if the coupling is assumed frequency-variant. Unlike earlier work, our derivation shows how the sign of the coupling coefficient can be obtained. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. [source] A T-type fractal boundary single-feed circularly polarized microstrip antennaINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 2 2009P. Nageswara Rao Abstract A single-feed T-type fractal boundary microstrip antenna is presented. It is established that a very good circular polarization is realizable with 3-dB axial ratio bandwidth of 1.27% at the center frequency of 2446 MHz by changing the electrical length in two directions of the square patch by using T-type fractal curve as boundary. Further it is shown that the surface area occupied by the antenna is reduced compared to the Euclidean shaped patch antenna without much degradation in gain of the antenna. Experimental results are compared with simulated results and a very good agreement is obtained. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source] Rotationally symmetric FDTD for wideband performance prediction of TM01 DR filtersINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2002Andrew R. Weily Abstract The generalized perfectly matched layer (GPML) coupled with rotationally symmetric (RS)-FDTD method has been utilized to extract the S-parameters for several probe-coupled TM01 dielectric resonator (DR) filters to directly obtain the theoretical wideband spurious performance. The computationally efficient (RS)-FDTD method has also been used to obtain accurate filter parameters for TE01 and TM01 dielectric resonators loaded in cylindrical cavities. The RS-FDTD method combined with digital filtering and the Matrix Pencil technique are used to analyze the resonant frequencies, inter-resonator coupling, and external Q values. When perturbation theory is used with RS-FDTD, accurate values of unloaded Q are obtained. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 259,271, 2002. [source] Linear-dendritic copolymers as nanocatalystsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2009M. Adeli Abstract Functionalized poly(ethylene glycol) (PEG) containing four chloride end functional groups (PEG-Cl4) was synthesized through reaction between cyanuric chloride and PEG-(OH)2. Chloride end functional groups of PEG-Cl4 were able to initiate the ring opening polymerization of 2-ethyl-2-oxazoline and star copolymers containing a PEG core, and poly(2-ethyl-2-oxazoline) (POX) arms were obtained. Polymerization was quenched using diethanolamine, and star copolymers containing hydroxyl end functional groups (PEG-POX-OH) were obtained. ,-Caprolactone was then polymerized using the hydroxyl end functional groups of star copolymers and amphiphilic linear-dendritic copolymers containing PEG and POX, and poly(caprolactone) (PCL) blocks were synthesized. Linear-dendritic copolymers were able to load the organic and inorganic guest molecules. Application of host-guest systems such as nanocatalyst for Heck chemical reaction was also investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Preparation of normal-phase HPLC stationary phase based on monodisperse hydrophilic polymeric beads and their applicationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Bolin Gong Abstract The monodisperse, 5.0 ,m hydrophilic macroporous poly(glycidymethacrylate- co -ethylenedimethacrylate) beads were first prepared based on monosized linear poly(glycidylmethacrylate) beads as seed by using a single-step swelling and polymerization method. The seed beads prepared by dispersion polymerization exhibited good absorption of the monomer phase. The pore size distribution of the beads was evaluated by mercury instrusion method. The surface area was calculated from the BET isotherms of nitrogen adsorption and desorption. The beads were modified to be a normal-phase liquid chromatographic (NPLC) stationary phase for high performance liquid chromatography (HPLC) in the following steps. First, the beads were completely hydrolyzed. Second, hydrolyzed particles were reacted with epichlorihydrin followed by another hydrolysis of the newly introduced epoxide groups. The retention properties of the NPLC stationary phase were easily modulated by changes in the composition of the mobile phase. The performance of theses beads was demonstrated with the separation of a variety of polar compounds. The satisfactory results were obtained. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Removal of fluoride using some lanthanum(III)-loaded adsorbents with different functional groups and polymer matricesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2003Luo Fang Abstract Although fluoride is beneficial for human beings in small quantities, it causes dental fluorosis when consumed in larger quantities over a period of time. In recent years, considerable work has been conducted for the purpose of developing new and low cost absorbents for adsorptive removal of fluoride, especially chelating resins loaded with metal ions. In the present study, several types of adsorbents with different functional groups loaded with lanthanum(III) were prepared to be used for fluoride removal from water. The optimum conditions for loading lanthanum(III) on the adsorbents and the effects of pH and initial fluoride concentration as well as shaking time and solid,liquid ratio on the removal of fluoride have been investigated. Based on these fundamental data, the removal of fluoride from actual hot spring water was also tested as a practical application by comparing the efficiency of different adsorbents for the removal of fluoride from hot spring water. The following conclusions were obtained. (1) The different chemical composition and chemical structure of the polymer matrix play the most important role in fluoride adsorption, (2) strongly acidic adsorbents are more effective on fluoride removal at neutral pH than weakly acidic adsorbents, (3) the order of fluoride removal in the neutral pH range of 4.5,8.0 by the different La(III)-loaded adsorbents employed in the present work is as follows: 200CT resin > POJRgel > IR124resin > SOJR gel , CPAgel , WK11 resin. The column experiments showed that the 200CT resin loaded with lanthanum(III) at pH 6.0 can be successfully employed for the removal of fluoride ions from actual hot spring water. Copyright © 2003 Society of Chemical Industry [source] Quantum bits with polyacetyleneJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 9 2002Andre Elvas Pereira Da Silva Abstract The dynamics of a polyacetylene single chain as a system for possible physical implementations of quantum bits is determined. This novel proposition is studied by varying intensity and duration of application of an electric field as well as the intensity, number, and position in the polymer chain of impurity molecules. The behavior of soliton pairs, whose associated energy levels form the quantum bit, is analyzed. The chain is modeled by a modified Pariser,Parr,Pople Hamiltonian extended to include the effects of an external electric field and the parameters of the impurity molecules. The effect of the variation of the field and impurities on the separation of the energy levels associated with soliton pairs is analyzed by numerical integration of the equations of motion. Two different approaches for controlling the separation of levels are presented, and their features compared. First, the use of changes in the electric field to control the distance (and ultimately coupling) between two solitons moving freely on the chain or captured by the potential generated by the impurity molecules. Second, the change in the intensity of the impurities alone, with no application of an external field. We have found that the effect of the use of the field on the separation of levels is much smaller than the one obtained by changes in the parameters of the impurity molecules, which eventually led us to achieve quantum bit behavior in a polyacetylene chain. The influence of the field and impurity parameters in the energy levels is determined, as well as their role in the coupling of the two solitons on the chain. Critical values for distance between solitons, intensity of field, and impurities that determine whether a pair of solitons can work as a quantum bit are obtained. © 2002 Wiley Periodicals, Inc. J Comput Chem 9: 870,873, 2002 [source] Type synthesis of 5-DOF parallel manipulators based on screw theoryJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2005Xianwen Kong With the introduction of virtual chains to represent the motion patterns of 5-DOF motions, a classification of 5-DOF PMs (parallel manipulators) is proposed at first. A general method for the type synthesis of 5-DOF PMs is then proposed based on screw theory and using the concept of virtual chains. The type synthesis of US-equivalent PMs is presented in detail to show the application of the proposed approach. US-equivalent PMs are the parallel counterparts of the 5-DOF US serial manipulators. For a US-equivalent PM, the moving platform can rotate arbitrarily about a point moving along a spherical surface. The type synthesis of legs for US-equivalent PKCs (parallel kinematic chains), the type synthesis of US-equivalent PKCs, as well as the selection of actuated joints of US-equivalent PMs are dealt with in sequence. US-equivalent PKCs with and without inactive joints are synthesized. Several US-equivalent PMs as well as other classes of 5-DOF PMs with identical type of legs are obtained. © 2005 Wiley Periodicals, Inc. [source] Size ramsey numbers of stars versus 4-chromatic graphs,JOURNAL OF GRAPH THEORY, Issue 3 2003Oleg PikhurkoArticle first published online: 31 JAN 200 Abstract We investigate the asymptotics of the size Ramsey number î(K1,nF), where K1,n is the n -star and F is a fixed graph. The author 11 has recently proved that r,(K1,n,F)=(1+o(1))n2 for any F with chromatic number ,(F)=3. Here we show that r,(K1,n,F), n2+o(n2), if , (F) , 4 and conjecture that this is sharp. We prove the case ,(F)=4 of the conjecture, that is, that r,(K1,n,F)=(4+o(1))n2 for any 4-chromatic graph F. Also, some general lower bounds are obtained. © 2003 Wiley Periodicals, Inc. J Graph Theory 42: 220,233, 2003 [source] | ||||||||||||||||||||||||||||