bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology Evolution in the Early Stages of Olefin Polymerization
Authors: Zheng Xuejing , Loos Joachim 
Published: March 2006

AbstractThe olefin polymerizations were carried out by using silica supported metallocene/MAO catalysts and MgCl2 supported Ziegler‐Natta catalysts under mild reaction conditions and stopped at very low yield. The surface and cross sectional morphology of the polymer particles were characterized by using scanning electron microscopy (SEM). A homogeneous distribution of (co)catalyst on the support material is a prerequisite condition to get a homogeneous fragmentation and uniform polymer particle morphology. In the present work the catalysts show two different fragmentation behaviors. They can gradually fragment from the outer to the inner surface of the catalyst particle, or instantaneously break up into a large amount of small sub‐particles at the beginning of the polymerization. The incorporation of comonomer does not change the general catalyst fragmentation scheme but delays the catalysts break‐up progress.
Novel Initiators for Thermally and UV‐Triggered ROMP
Authors: Zhang Yan , Wang Dongren , Lönnecke Peter , Scherzer Thomas , Buchmeiser Michael R. 
Published: March 2006

AbstractNovel ruthenium‐based photoactive transition metal catalysts, i.e. [Ru(CF3CO2)2(p‐cymene)(IMes)] (2), [Ru(CF3CO2)2(PhNC)3(IMes)] (3), [Ru(CF3CO2)2(p‐cymene) (IMesH2)] (4), [Ru(CF3CO2)2(PhNC))3(IMesH2)] (5), have been prepared and investigated for their use as initiators for the thermally and photo‐initiated ring‐opening metathesis polymerization (photo‐ROMP). The polymerization behavior of the novel systems for both norborn‐2‐ene and functional monomers, such as norborn‐5‐ene‐ 2‐ylmethanol, has been investigated.
Single‐Site Organochromium Catalysts: Synthesis, Characterisation by Paramagnetic NMR and Olefin Polymerisation
Authors: Enders Markus 
Published: March 2006

AbstractChromium(III)‐complexes with monoanionic spectator ligands allow the preparation of highly active catalysts for ethylene polymerisation. We summarize the synthesis and NMR‐spectroscopic investigations of precatalysts with quinolyl‐functionalised Cp‐ligands. These complexes have advantageous properties. For spectroscopic investigations the rigidity of the ligand framework helps to identify the species present in solution as fewer conformers are possible. For the application as polymerisation catalysts the high stability of the activated catalyst is important. We obtained meaningful analytical data by paramagnetic NMR, combined with DFT‐calculation of the spin‐density. These and other investigations lead to the conclusion, that the active species is a cationic chromium(III)alkyl complex. However, at present we have not enough information about the exact structure of this species in the absence of coordinating solvent molecules.
Methylalumoxane (MAO)‐Derived MeMAO− Anions in Zirconocene‐Based Polymerization Catalyst Systems – A UV‐Vis Spectroscopic Study
Authors: Wieser Ulrich , Schaper Frank , Brintzinger Hans‐Herbert 
Published: March 2006

AbstractReaction of Me2Si(Ind)2ZrCl2 with excess methylalumoxane (MAO) gives rise to ion pairs containing zirconocenium cations of the type [Me2Si(Ind)2ZrMe]+ in contact with two types of anions, MeMAOA− and MeMAOB−, which differ in their coordinative strengths: More strongly coherent contact‐ion pairs [Me2Si(Ind)2 ZrMe+..MeMAOB−] are converted by a sufficiently high excess of MAO to more easily separable contact‐ion pairs [Me2Si(Ind)2ZrMe+..MeMAOA−], which react with AlMe3 to form the outer‐sphere ion pairs [Me2Si(Ind)2Zr(µ‐Me)2AlMe2]+ MeMAOA−, and are likely to be required also for the formation of the olefin‐containing reaction complexes responsible for catalytic activity.
Solvent‐Ligated Transition Metal Complexes as Initiators for the Polymerization of Isobutene
Authors: Nuyken Oskar , Vierle Mario , Kühn Fritz E. , Zhang Yanmei 
Published: March 2006

AbstractAfter a brief introduction of the history of polyisobutene and the description of an interesting commercial process, this article is focused on the mechanism of the isobutene initiation and propagation. Furthermore, the INIFER technique will be briefly discussed. Finally, it will be shown that polyisobutene with a high content of terminal olefinic groups can be synthesized by using transition metal complexes in homogeneous solution at room temperature. Mechanisms of the isobutene polymerization initiated by this new class of initiators will be suggested.
Microkinetic Videomicroscopic Analysis of the Olefin‐Copolymerization with Heterogeneous Catalysts
Authors: Ferrari Daniela , Knoke Stefan , Tesche Bernd , Fink Gerhard 
Published: March 2006

AbstractVideomicroscopy as a tool for investigating olefin gas phase co‐polymerization is presented in this paper. This technique enables the simultaneous detection of the individual growth of a large number of catalyst particles. The focus is to study the kinetic behaviour of different types of Ziegler‐ and metallocene catalysts and to demonstrate that videomicroscopy can help to assign a given catalyst system to the appropriate model. Further, the density problem, the estimation of activation energies of single grains, the particle volume enlargement of amorphous copolymers and the comonomer effect are adressed.
Metal Complexes for the Vinyl Addition Polymerization of Norbornene: New Compound Classes and Activation Mechanism with B(C6F5)3/AlEt3
Authors: Janiak Christoph , Lassahn Paul‐Gerhard , Lozan Vasile 
Published: March 2006

AbstractClasses of mainly nickel(II) and palladium(II) complexes are comparatively presented in their norbornene polymerization activity to vinyl polynorbornene when activated with methylalumoxane, MAO, tris(pentafluorophenyl)borane/triethylaluminum, B(C6F5)3/AlEt3 or even B(C6F5)3 alone. Classes include Ni and Pd complexes with α‐dioxime ligands, salts with [PdCl4]2− and [Pd2Cl6]2− units, dinuclear Ni and Pd complexes with multidentate Schiff‐base ligands, polynuclear Ni‐ and Cr/Ni‐carboxylate cage complexes, and dihalo(bisphosphane) Ni and Pd complexes. The study of activation mechanism by 31P‐ and 19F‐NMR together with X‐ray structural data points to the formation of PdCl2 units and “naked” Pd2+ cations as highly active species.
Oral methylphenidate fails to elicit significant changes in extracellular putaminal dopamine levels in Parkinson's disease patients: Positron emission tomographic studies
Authors: Koochesfahani Kaveh M. , de la Fuente‐Fernández Raúl , Sossi Vesna , Schulzer Michael , Yatham Lakshmi N. , Ruth Thomas J. , Blinder Stephan , Stoessl A. Jon 
Published: March 2006

AbstractIn this study, we assessed the changes of endogenous dopamine (DA) levels in response to methylphenidate in 5 patients with idiopathic Parkinson's disease (PD) and 6 healthy controls. Three‐dimensional positron emission tomography was performed with the D2 receptor antagonist [11C]raclopride (RAC) at baseline and 1 hour following the administration of oral methylphenidate (0.8 mg/kg) to assess changes in dopamine levels indirectly. Oral methylphenidate produced no significant change in extracellular DA levels in the putamen, as estimated by comparing changes in RAC binding at baseline and 1 hour following its administration in PD subjects and healthy controls. However, there were small changes in RAC binding of opposite direction in caudate and ventral striatal regions compared between the two groups. Although there was no consistent improvement in motor function in the PD group, some patients did experience a subjective high in response to methylphenidate (MP). Failure of oral MP to alter extracellular DA levels in putamen could result from degeneration of presynaptic dopaminergic terminals, with consequent severe reductions in the levels of endogenous DA and dopamine transporter in PD subjects. Our data provide in vivo neurochemical support for the lack of clinical efficacy following MP in PD patients and are also in keeping with reduced DA release following amphetamine in PD subjects. © 2006 Movement Disorder Society
Bladder dysfunction in Parkinsonism: Mechanisms, prevalence, symptoms, and management
Authors: Winge Kristian , Fowler Clare J. 
Published: March 2006

AbstractThe advent of functional imaging methods has increased our understanding of the neural control of the bladder. This review examines current concepts of the role of brain function in urinary control with particular emphasis on the putative role of dopamine receptors. Dopaminergic mechanisms play a profound role in normal bladder control and the dysfunction of these may result in symptoms of overactive bladder in Parkinsonism. The importance of this nonmotor disorder has been overlooked. We address the problem of bladder dysfunction as it presents to patients and their neurologist. The prevalence of bladder symptoms in Parkinson's disease is high; the most common complaint is nocturia followed by frequency and urgency. In multiple‐system atrophy, the combination of urge and urge incontinence and poor emptying may result in a complex combination of complaints. The management of bladder dysfunction in Parkinsonism addresses treatment of overactive detrusor as well as incontinence. © 2006 Movement Disorder Society
Application of time modulation in the synthesis of sum and difference patterns by using linear arrays
Authors: Fondevila J. , Brégains J. C. , Ares F. , Moreno E. 
Published: March 2006

AbstractIn this paper, time modulation is applied to a small number of elements of a linear array that radiates either sum or difference patterns, in order to take control over their sidelobe levels. The simulated annealing (SA) technique helps to obtain the optimum time pulses applied to such elements in terms of sideband minimization. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 829–832, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21489
Envelope correlation in (N, N) MIMO antenna array from scattering parameters
Authors: Thaysen Jesper , Jakobsen Kaj B. 
Published: March 2006

AbstractA simple closed‐form equation to calculate the envelope correlation between any two receiver or transmitter antennas in a multi‐input multi‐output (MIMO) system of an arbitrary number of elements is derived. The equation uses the scattering parameters obtained at the antenna feed point to calculate the envelope correlation coefficient. This approach has the advantage that it does not require knowledge of the antenna radiation pattern. Numerical data that include conductor and permittivity loss are shown to validate the approach. Using the scattering parameters for calculating the envelope correlation is less laborious and relatively cheaper, as compared to the radiation pattern approach. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 832–834, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21490
Ultra‐wideband Vivaldi antenna design for multisensor adaptive ground‐penetrating impulse radar
Authors: Turk Ahmet Serdar 
Published: March 2006

AbstractThis paper describes a partially dielectric‐loaded Vivaldi antenna (PDVA) structure that maintains ultra‐wideband antenna characteristics over a bandwidth ratio greater than 25:1 so as to improve the impulse radiation characteristics for multisensor adaptive ground‐penetrating Radar (GPR) operations. The PDVA is introduced for metal‐detector‐combined GPR head designs in order to avoid performance degradations based on the sensor interferences. It is shown that high gain, low input reflection, and signal‐ringing levels over the wide operational bands are attainable for a PDVA with proper dielectric and absorber loadings. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 834–839, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21491
An arbitrary dual‐band microstrip hybrid‐ring
Authors: Dwari Santanu , Sanyal Subrata 
Published: March 2006

AbstractThis paper presents the realization of a dual‐band hybrid‐ring and gives the design formulas. The simulated and measured results of a microstrip dual‐band hybrid‐ring operating at 900/1900 MHz are shown to have good agreement and exhibit good performance at both frequency bands. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 840–842, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21492
L‐band all‐optical gain‐clamped erbium‐doped fiber amplifier via ASE reflection technique
Authors: Zhang Hao , Dou Qingying , Jin Yanli , Guo Tuan , Liu Lihui , Liu Yange , Yuan Shuzhong , Dong Xiaoyi 
Published: March 2006

AbstractWe present an L‐band all‐optical gain‐clamped erbium‐doped fiber amplifier with a fiber‐loop mirror as the ASE reflector. By using the combination of a C/L‐band wavelength division multiplexer (WDM) and fiber‐loop mirror, the backward C‐band amplified spontaneous emission (ASE) is reflected back into the erbium‐doped fiber and works as the control light. The static gain level of this amplifier can be adjusted by changing the ASE feedback. The experimental results show that the EDFA gain can be effectively clamped via this ASE reflection technique. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 852–854, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21496
Compact dual‐band antenna for DCS/2.4 GHz WLAN applications
Authors: Joseph Manoj , Raj Rohith K. , Suma M. N. , Mohanan P. 
Published: March 2006

AbstractA compact dual‐band antenna operating in the 1.8/2.4‐GHz bands with identical linear polarization suitable for DCS/2.4‐GHz WLAN applications is presented. The proposed configuration is a modified microstrip‐fed printed monopole with an additional strip and a proper truncated ground plane on the opposite side of the substrate. The proposed antenna of dimensions 35 × 47 × 1.6 mm offers 2:1 VSWR bandwidths of 10.8% and 9.8% in the DCS and 2.4‐GHz WLAN bands, respectively. Details of the antenna design and experimental results are discussed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 856–859, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21498
A miniaturized antenna for surface‐to‐surface and surface‐to‐orbiter applications
Authors: Nessel James A. , Zaman Afroz J. , Miranda Félix A. 
Published: March 2006

AbstractA folded Hilbert curve fractal antenna (fHCFA) which produces end‐fire radiation at the S‐band and broadside radiation at the Ku‐band without switches is presented. The measured gains/bandwidths were 1.2 dBi/10 MHz and 5.4 dBi/500 MHz at 2.3 GHz (S‐band) and 16.8 GHz (Ku‐band), respectively. This work offers a compact antenna design as a candidate for robotic applications in future NASA planetary exploration missions. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 859–862, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21499
Wideband dual‐polarized antenna array on finite conducting cylinder
Authors: Lai H. W. , Wong T. P. , Mak C. L. , Luk K. M. 
Published: March 2006

AbstractA wideband dual‐polarized patch antenna array on a finite conducting cylinder is proposed for MIMO applications. By employing the L‐probe coupling method and the phase‐cancellation technique, a dual‐polarized antenna array with characteristics of wide bandwidth and high isolation (1.85–2.24 GHz,S12< −32 dB) was designed, fabricated, and tested. The proposed antenna is suitable for various wireless communication applications, including smart antenna and MIMO system designs. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 862–866, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21500
High gain Er3+‐doped fiber amplifier with double‐pass preamplification stage
Authors: Bouzid Belloui , Abdullah M. K. , Mahdi M. A. 
Published: March 2006

AbstractA new architecture of dual‐stage erbium‐doped fiber amplifier with double‐pass preamplification is successfully demonstrated. A maximum gain of 52 dB is obtained at −50‐dBm signal power with 1550‐nm signal wavelength. An efficient filtering of amplified spontaneous emission improves gain at the signal wavelength up to 18 dB in the double‐pass amplifier section. The noise‐figure penalty is very minimal in the small‐signal range, compared to the dual‐stage amplifier without bandpass filters. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 866–868, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21501
Internal composite monopole antenna for WLAN/WiMAX operation in a laptop computer
Authors: Wong Kin‐Lu , Chou Liang‐Che 
Published: March 2006

AbstractA novel composite monopole antenna suitable for 2.4/5.2/5.8‐GHz wireless local area network (WLAN) and 2.5/3.5/5‐GHz worldwide interoperability for microwave access (WiMAX) operation is presented. The composite monopole antenna comprises a ceramic chip radiating element as arm 1 of the antenna and a printed radiating element as arms 2 and 3 of the antenna. The three arms effectively control three excited wide resonant modes for WLAN/WiMAX operation, and the total area occupies by the composite monopole antenna is 8 × 19.5 mm2 only, which is much smaller than that of a corresponding printed monopole antenna. Due to the compact area occupied, the proposed antenna is promising to be embedded within the narrow spacing between the casing of the laptop computer and the supporting metal frame of the display as an internal antenna. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 868–871, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21502
A wideband printed monopole antenna for 2.4‐GHz WLAN applications
Authors: Suma M. N. , Bybi P. C. , Mohanan P. 
Published: March 2006

AbstractA planar monopole antenna suitable for broadband wireless communication is designed and developed. With the use of a truncated ground plane, the proposed printed monopole antenna offers nearly 60% 2:1 VSWR bandwidth and good radiation characteristics for the frequencies across the operating band. A parametric study of the antenna is performed based on the optimized design, and a prototype of the antenna suitable for 2.4‐GHz WLAN application is presented. The antenna can be easily integrated into wireless circuitry and is convenient for application in laptop computers. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 871–873, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21503
A study of terminated hermite lossless nonuniform transmission lines using mathematica
Authors: Torrungrueng D. , Chou P. Y. , Krairiksh M. 
Published: March 2006

AbstractThe terminated Hermite lossless nonuniform transmission line (HLNUTL) in the steady state is studied in this paper. Due to the complicated equations associated with HLNUTLs, numerical simulations based on Mathematica software are convenient for understanding the propagation physics of HLNUTLs. It is found that HLNUTLs have distinct characteristics compared to other types of transmission lines. For example, it is necessary to match HLNUTLs with reactive loads. The results are verified through case studies by checking the power conservation. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 888–892, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21508
Scattering by a nihility sphere
Authors: Lakhtakia Akhlesh 
Published: March 2006

AbstractOn interrogation by a plane wave, the back‐scattering efficiency of a nihility sphere is identically zero, and its extinction and forward‐scattering efficiencies are higher than those of a perfectly conducting sphere. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 895–896, 2006; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21510
Time‐slot interchanging using the crosspoint switch and a recirculating buffer
Authors: Geldenhuys R. , Wang Z. , Chi N. , Tafur Monroy I. , Koonen A. M. J. , Dorren H. J. S. , Leuschner F. W. , Khoe G. D. , Yu S. 
Published: March 2006

AbstractBecause of the low crosstalk of the CrossPoint switch, multiple recirculations are possible. This facilitates simplified time‐slot interchange configurations that depend on less fiber‐delay lines, and single time‐slot granularity to enable a short total‐delay time. Error‐free time‐slot interchange is demonstrated with a 10‐Gb/s payload. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 897–900, 2006; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21511
A compact bandpass filter using open‐loop and C‐SCMRC resonators with harmonic suppression
Authors: Gu Jian‐Zhong , Wang Chuang , Sun Xiao‐Wei 
Published: March 2006

AbstractA novel compact open‐loop resonator bandpass filter is proposed to suppress the spurious passband using a compensated spiral compact microstrip resonant cell (C‐SCMRC). Due to the inherently compact and stopband characteristics of the C‐SCMRC, the proposed filters shows a better spurious‐rejection performance than the only open‐loop resonator filter. The proposed bandpass filter improves the rejection level of 20 dB from 2.8 to 5 GHz. Furthermore, 40‐dB suppression improvement and better than 57‐dB rejection level at the 2nd‐harmonic passband from 3.3 to 3.85 GHz are achieved. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 906–909, 2006; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21514
Modified Sierpinski fractal monopole antenna with Descartes circle theorem
Authors: Liu Ji‐Chyun , Wu Ching‐Yang , Chen Chen‐Hsiang , Chang Dau‐Chyrh , Chen Jong‐Yih 
Published: March 2006

AbstractAn innovative modified Sierpinski fractal monopole antenna with multiband performance is proposed in this paper. By using the Descartes circle theorem and a self‐similar iteration design, the antenna is constructed with circular fractal patterns. The resonances exhibit the log periodic characteristic, and the radiation field presents array patterns. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 909–911, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21515
Design of a weathercock‐shaped microstrip patch antenna with a T‐slot for the Hiper‐LAN band
Authors: Choi Sun‐Ho , Yoon Joong‐Han , Lee Hwa‐Choon , Kwak Kyung‐Sup 
Published: March 2006

AbstractIn this paper, a weathercock‐shaped microstrip patch antenna for application in a Hiper‐LAN is designed and fabricated. To obtain sufficient bandwidth when VSWR < 2, the T‐slot is inserted in the patch and a coaxial‐probe source is used. The measured result of the fabricated antenna is 350 MHz or about 7.62% bandwidth when VSWR < 2, referenced to the center frequency, with gain of 5.25–6.70 dBi. The experimental 3‐dB beam width is seen to be broad across the passband for the azimuth and the elevation at 80.32° and 83.88°, respectively. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 911–913, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21516
Microstrip bandpass filter using a triangular‐patch resonator with three transmission zeros
Authors: Li JiaLin , Chen JianXin , Xia Lei , Xue Quan , Xue LiangJin 
Published: March 2006

AbstractA microstrip bandpass filter (BPF) using a triangular patch resonator is introduced in this paper. With one coupling gap between the input and output ports together with the patch configurations, the filter can realize DC block, lower insertion loss, and higher power‐handling capability. For demonstration purposes, a filter of this type is designed, fabricated, and tested and the measured results for the fabricated BPF show good consistency with the calculated results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 914–915, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21517