bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mathematical analysis and stability of a chemotaxis model with logistic term
Authors: Tello J. Ignacio 
Published: June 2004

AbstractIn this paper we study a non‐linear system of differential equations arising in chemotaxis. The system consists of a PDE that describes the evolution of a population and an ODE which models the concentration of a chemical substance. We study the number of steady states under suitable assumptions, the existence of one global solution to the evolution problem in terms of weak solutions and the stability of the steady states. Copyright © 2004 John Wiley & Sons, Ltd.
On the growth of filamentary structures in planar media
Authors: Andreucci D. , Herrero M. A. , Velázquez J. J. L. 
Published: June 2004

AbstractWe analyse a mathematical model for the growth of thin filaments into a two dimensional medium. More exactly, we focus on a certain reaction/diffusion system, describing the interaction between three chemicals (an activator, an inhibitor and a growth factor), and including a fourth cell variable characterising irreversible incorporation to a filament. Such a model has been shown numerically to generate structures shaped like nets. We perform an asymptotical analysis of the behaviour of solutions, in the case when the system has parameters very large and very small, thereby allowing the onset of different time and space scales. In particular, we describe the motion of the tip of a filament, and the changes in the relevant chemical species nearby. Copyright © 2004 John Wiley & Sons, Ltd.
Bandwidth enhancement of circularly polarized microstrip patch antenna using multiple L‐shaped probe feeds
Authors: Lo Wai‐Kwok , Chan Chi‐Hou , Luk Kwai‐Man 
Published: June 2004

AbstractImpedance‐bandwidth enhancement of microstrip antennas using an L‐shaped probe feed has previously been demonstrated. In this paper, axial‐ratio bandwidth enhancement is achieved for circularly polarized (CP) microstrip patch antenna using dual and four L‐shaped probe feeds. By controlling the excitation phase and angular orientation of the horizontal portion of each L‐probe, circular polarization can be generated with wide axial‐ratio bandwidth by exciting the circular patch. In the dual L‐shaped probe case, the impedance and axial‐ratio bandwidth are 42% and 27.23%, respectively. On the other hand, for the four L‐shaped probes case, both of these figures increase to 45%. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 263–265, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20272
Cancellation of local oscillator phase‐noise in 60‐GHz high‐data‐rate wireless systems
Authors: Loyez C. , Fryziel M. , Boe A. , Rolland N. , Rolland P. A. 
Published: June 2004

AbstractA cancellation device of phase‐noise is implemented in a wireless system at 60 GHz. By using only MMIC VCOs to perform frequency conversions, such a system effectively transmits signals with a QPSK‐modulation scheme. For a 50 Mb/s data‐rate, performances are similar to that of an ideal conventional system. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 268–272, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20274
A three‐stage Ka band PHEMT wideband amplifier MMIC
Authors: Huang C. W. , Chang S. J. , Wu W. , Wu C. L. , Chang C. S. 
Published: June 2004

AbstractIn this paper, a Ka‐Band 24‐dBm AlGaAs/InGaAs/GaAs PHEMT MMIC power amplifier is demonstrated. This three‐stage amplifier is designed to fully match for 50Ω input and output impedances. With 4 V and 250‐mA DC bias, we achieve 15‐dB small‐signal gain, 24 dBm P−1dB, 24.3% PAE, and better than 10‐dB input return loss from 31 to 37 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 277–280, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20277
Broadband millimeter‐wave planar antenna array with a waveguide and microstrip‐feed network
Authors: Oh Soon‐Soo , Heo John , Kim Dong‐Hyeon , Lee Jae‐Wook , Song Myung‐Sun , Kim Young‐Sik 
Published: June 2004

AbstractIn this paper, we describe a fixed‐beam broadband planar antenna array at millimeter‐wave frequencies. The antenna is fed by waveguide‐feed and microstrip‐feed networks. In order to ensure fixed beams and a broad bandwidth, a subarray concept is introduced. For efficient coupling, a novel waveguide‐to‐slot transition consisting of a slot pair and a narrow conductive bar is proposed. Simulated and measured bandwidth is found to be more than 7.1% from 40.5–43.5 GHz. The main beam directions are broadside over all frequencies. The maximum measured antenna gain is 30.2 dBi at 42.0 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 283–287, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20279
An internal metal‐plate antenna for a folder‐type mobile phone
Authors: Chiu Ching‐Yuan , Wong Kin‐Lu 
Published: June 2004

AbstractA compact shorted metal‐plate antenna suitable to be concealed within the casing of a folder‐type mobile phone as an internal antenna is presented. A design example of the proposed antenna for operating in the UMTS band (1920–2170 MHz) is demonstrated. Details of the experimental results of the constructed prototypes are presented and discussed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 294–296, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20282
Pattern‐reconfigurable quasi‐yagi microstrip antenna using a photonic band gap structure
Authors: Yang Xue‐Song , Wang Bing‐Zhong , Zhang Yong 
Published: June 2004

AbstractA pattern‐reconfigurable quasi‐Yagi microstrip antenna is presented. Its main beam in the E‐plane can scan from −66° to +63° in the upper‐half space by using a switch‐controlled photonic band gap (PBG) structure, while maintaining an operating frequency of approximately 9.65 GHz. The antenna is analyzed using Ansoft HFSS. The measured and simulated results of the three configurations of the antenna are provided. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 296–297, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20283
Fast analysis of interconnect response illuminated by an external electromagnetic field using G‐FDTD
Authors: Jin Hong‐Fang , Li Er‐Ping , Wang Sheng , Li Le‐Wei , Yuan Wei Liang 
Published: June 2004

AbstractA modified finite‐difference time‐domain (FDTD) method, called generalized total‐field/scattered‐field (G‐TF/SF) FDTD, is applied to compute the interconnect response on an infinite dielectric substrate illuminated by an external electromagnetic field. This method is also extended form 2D to 3D. The current distributions on the strips obtained by using the 3D G‐FDTD method are presented and are in good agreement with the results computed via the method of moments (MoM). The simulation results indicate that this method is efficient and accurate for the modeling of an infinite scatterer problem with a compact FDTD grid. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 304–307, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20286
Dual‐frequency and dual‐polarization multilayer microstrip antenna element
Authors: Michail Georgios Ch. , Uzunoglu Nikolaos K. 
Published: June 2004

AbstractA dual‐frequency and dual‐linear polarization multilayer microstrip antenna element for array‐antenna applications is presented. The performance of the element was computed using a commercial software based on the finite‐element‐method (FEM) algorithm. A prototype with dimensions based on the simulations was built and tested. Good agreement between the measured and numerical results is obtained. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 311–315, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20288
Effect of metal contact's reflection on the effective coupling coefficient of second‐order DFB laser diodes
Authors: Zhong Yuan , Zhu Xiaopeng , Song Guofeng , Huang Yidong , Chen Lianghui 
Published: June 2004

AbstractFor a second‐order DFB‐LD, the presence of a metal contact layer can reduce 1st‐order radiation. Part of the reflected power is redistributed into guided modes and results in a variation of the effective coupling coefficient κeff. In this paper, we study the effect of the Au top contact's reflection on the κeff of 2nd‐order DFB lasers. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 339–342, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20296
A 2‐watt balanced power amplifier MMIC for Ku‐band satellite communications
Authors: Kim Jeong‐Geun , Park Hyun‐Min , Kim Jae‐Young , Jeon Sun‐Ik , Hong Songcheol 
Published: June 2004

AbstractA Ku‐band power amplifier MMIC has been developed using 0.25‐μm GaAs pHEMT technology. To achieve small chip size and simple drain‐bias connection, a bus‐bar power combiner is used. Also, balanced‐power amplifier topology is used to obtain good input/output return losses. The small‐signal gain is about 15 dB and the gain variation is less than 1 dB from 12 to 17 GHz. Good input/output return losses are achieved at less than −15 dB due to the balanced topology.P1dBof 32.6 dBm and PAE of 23.5% are achieved at 14 GHz. The effective chip area is 4.2 × 3.2 mm. Because the power amplifier is implemented using the balanced topology with the bus‐bar power combiner, compact size, high output power, and good input/output return losses can be achieved simultaneously. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 342–344, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20297
Remarks on “A 2D TLM model for electromagnetic wave propagation in Tellegen media”
Authors: Mackay Tom G. 
Published: June 2004

AbstractCabeceira et al. recently presented a time‐domain analysis of wave propagation in a Tellegen medium [1]. Their analysis is ill‐founded because (i) the existence of any Tellegen medium is not tenable within modern electromagnetic theory; and (ii) the constitutive relations employed are not consistent with the principle of causality.© 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 345–346, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20298
Melting point depression and cocrystallization behavior of poly(ethylene‐co‐butylene 2,6‐naphthalate) copolymers
Authors: Papageorgiou George Z , Achilias Dimitris S , Karayannidis George P 
Published: June 2004

AbstractThe melting point depression and cocrystallization behavior of a series of random poly(ethylene‐co‐butylene 2,6‐naphthalate) P(EN‐co‐BN) copolymers were investigated using differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD). These copolymers crystallize over the entire range of composition and they exhibit eutectic behavior. WAXD patterns showed that copolymers form exclusively poly(ethylene 2,6‐naphthalate) (PEN) type crystals or poly(butylene 2,6‐naphthalate) (PBN) type crystals. A transition from the PEN‐ to PBN‐type crystal was observed in the middle of the copolymer composition. This confirms that the P(EN‐co‐BN) copolymers show isodimorphic cocrystallization. The cocrystallization was thermodynamically analyzed using the Wendling–Suter model. The defect free energy was found to be about 12.17 kJ mol−1 in the case of incorporation of BN units in the PEN‐type crystals, and about 5.66 kJ mol−1 in the case of incorporation of EN units in the PBN‐type crystal. This means that the incorporation of bulkier BN units in the PEN crystals is more difficult. For low comonomer concentrations it was found that comonomer exclusion is probable. Copyright © 2004 Society of Chemical Industry
Characterization of molecularly imprinted polymers employing crosslinkers with nonsymmetric polymerizable groups
Authors: Sibrian‐Vazquez Martha , Spivak David A. 
Published: June 2004

AbstractCrosslinking monomers have been developed with a combination of methacrylamide and methacrylate or vinyl ketone polymerizable groups that provide molecularly imprinted polymers (MIPs) with improved binding and selectivity. The differential reactivity rates of the polymerizable groups prompted an investigation into the time‐dependent behavior of the crosslinkers, which suggests a new mechanism for MIP formation. The mechanism involves the formation of long sections of linear poly(vinyl ketone) with pendant methacrylamide groups that form a highly crosslinked network in a subsequent step. This has implications for the sequence morphology of polymers, affecting the structure and improving the binding properties of MIPs. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3668–3675, 2004
Birefringence study of drawn Nafion films
Authors: Van Der Heijden Peter , Bouzenad Faycal , Diat Olivier 
Published: June 2004

AbstractNafion films are birefringent. This optical property has been studied as a function of the draw ratio to obtain insight into the film morphology. At small draw ratios, the structure shows biaxial behavior. At higher draw ratios (>150%), Nafion can be considered to have a uniaxial symmetry. The influence on the birefringence of three different counterions (hydrogen, lithium, and tetramethylammonium) is negligible. Undrawn Nafion shows preorientation, which can be eliminated with drawing in the proper direction. X‐ray experiments suggest that the physical origin of the birefringence in Nafion is mainly due to the orientation of the polymer chains and not due to deformation or form birefringence. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2857–2870, 2004
Synthesis of Energetic Polymers by the Introduction of Energetic Groups onto Polymeric Primary and Secondary Amines
Authors: Bellamy Anthony J. , King David S. , Golding Peter 
Published: June 2004

AbstractEnergetic polymers have been synthesised by the introduction of picryl groups onto linear polyethylenimine and polyvinylamine. The degree of substitution was 70–97% for polyethylenimine, depending upon the molecular weight of the polymer, and around 70% for polyvinylamine. N‐Picrylation of low molecular weight, model compounds was also studied. The results illustrate the influence of molecular weight on the chemical accessibility of a reaction site and reflect the difficulty of modelling polymer modification reactions using small molecules.
Ab Initio Calculation of BN Generation from Boron and Nitrogen Oxides
Authors: Wang Zhong , Li Shu Fen , Zhang Li Min , Sheng Zhen Yu , Yu Shu Qin 
Published: June 2004

AbstractBoron Nitride (BN) is one of the products produced in the burning of boron‐containing propellant. A possible reaction mechanism for the reactions of boron and nitrogen oxides (NO, NO2, N2O) has been studied using the G2MP2 method. The BN product can be formed in the reactions of B(4P) with NO, NO2 and N2O. Among these three reactions, B(4P)+NO2 and B(4P)+N2O are 181.42 kJ/mol and 160.92 kJ/mol more‐exothermic than the B(4P)+NO reaction. The barrier heights from intermediates to transition states are 64.85 kJ/mol and 111.75 kJ/mol for B(4P)+NO2 and B(4P)+N2O, respectively. However, in the reaction B(4P)+NO , the transition from intermediate to product (IM3→BN+O) is very endothermic by 420.70 kJ/mol. So B(4P)+ N2O→BN+NO and B(4P)+NO2→BN+O2 are more likely reactions to generate BN than B(4P)+NO→BN+O.
Synthesis, Crystal Structure and Theoretical Study of Tetranitrodiazidoacetylhexaazaisowurtzitane (TNDAIW)
Authors: Yukai Wu , Yuxiang Ou , Jinquan Liu , Lihua Liu , Boren Chen , Zhiguo Liu 
Published: June 2004

AbstractA novel polycyclic caged compound, tetranitrodiazidoacetylhexaazaisowurtzitane (TNDAIW), has been synthesized by a six‐step reaction. The molecular structures of two key intermediates and TNDAIW were identified. The crystal structure of the titled compound was established by X‐ray crystallography. Semi‐empirical MO calculations were performed with AM1 and PM3 methods based on the crystal structure. The corresponding data of β‐CL‐20 are also given for comparison.
Simulation of Explosive Welding with ANFO Mixtures
Authors: Mousavi A. A. Akbari , Burley Stephen J. , Al‐Hassani S. T. S. , Byers Brown W. 
Published: June 2004

AbstractThe work described here arose from a study into explosive welding. As part of that study, the impact velocity of stainless steel and titanium plates to grazing detonation of ANFO/perlite, the velocity of detonation were measured. Computer simulation required a new model which copes with an equation of state of low explosives.
Divergent Detonation Wave Processes in PBX Based on RDX
Authors: Mendes Ricardo A. L. , de A. Campos José L. S. , Plaksin Igor Y. , Ribeiro Jose M. B. M. 
Published: June 2004

AbstractIn order to characterize the initial phase of the divergent detonation wave in PBX, a hemispheric explosive sample was initiated by a long cylindrical charge of the same explosive. The tested PBX is composed of 85 wt% of RDX and 15 wt% of binder based on HTPB. This PBX‐RDX presents an effective density of 1.57 g/cm3, and a detonation velocity of 7.90 mm/μs.
Large‐scale prediction of protein geometry and stability changes for arbitrary single point mutations
Authors: Bordner A. J. , Abagyan R. A. 
Published: June 2004

AbstractWe have developed a method to both predict the geometry and the relative stability of point mutants that may be used for arbitrary mutations. The geometry optimization procedure was first tested on a new benchmark of 2141 ordered pairs of X‐ray crystal structures of proteins that differ by a single point mutation, the largest data set to date. An empirical energy function, which includes terms representing the energy contributions of the folded and denatured proteins and uses the predicted mutant side chain conformation, was fit to a training set consisting of half of a diverse set of 1816 experimental stability values for single point mutations in 81 different proteins. The data included a substantial number of small to large residue mutations not considered by previous prediction studies. After removing 22 (≈2%) outliers, the stability calculation gave a standard deviation of 1.08 kcal/mol with a correlation coefficient of 0.82. The prediction method was then tested on the remaining half of the experimental data, giving a standard deviation of 1.10 kcal/mol and covariance of 0.66 for 97% of the test set. A regression fit of the energy function to a subset of 137 mutants, for which both native and mutant structures were available, gave a prediction error comparable to that for the complete training set with predicted side chain conformations. We found that about half of the variation is due to conformation‐independent residue contributions. Finally, a fit to the experimental stability data using these residue parameters exclusively suggests guidelines for improving protein stability in the absence of detailed structure information. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Predicting interactions of winged‐helix transcription factors with DNA
Authors: Roberts Victoria A. , Case David A. , Tsui Vickie 
Published: June 2004

AbstractDetermining protein–DNA interactions is important for understanding gene regulation, DNA repair and chromatin structure. Unfortunately, the structures of DNA‐bound complexes are often difficult to obtain experimentally, so the development of computational methods that provide good models of these complexes would be valuable. Here, we present a rigid‐body docking approach using the computer program DOT. DOT performs a complete, six‐dimensional search of all orientations for two rigid molecules and calculates the interaction energy as the sum of electrostatic and van der Waals terms. DOT was applied to three winged‐helix transcription factors that share similar DNA‐binding structural motifs but bind DNA in different ways. Docking with linear B‐form DNA models accomplished several objectives; it (1) distinguished the different ways the transcription factors bind DNA, (2) identified each protein's DNA‐binding site and the DNA orientation at the site and (3) gave at least one solution among the three best‐ranked that shows the protein side chain–DNA base interactions responsible for recognition. Furthermore, the ensemble of top‐ranked, docked linear B‐DNA fragments indicated the DNA bending induced upon protein binding. Docking linear B‐DNA to structures of the transcription factor FadR suggests that the allosteric, conformational change induced upon effector binding results in loss of the ability to bend DNA as well as loss of sequence‐specific interactions with DNA. The electrostatic energy term calculated by DOT is comparable to the electrostatic binding energy calculated by Poisson–Boltzmann methods. Our results show rigid‐body docking that includes a rigorous treatment of the electrostatic interaction energy can be effective in predicting protein–DNA interactions. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Molecular dynamics simulation of C60 encapsulated in boron nitride nanotubes
Authors: Moon Won Ha , Son Myung Sik , Lee Jun Ha , Hwang Ho Jung 
Published: June 2004

AbstractThis issue's Editor's Choice [1] reports molecular dynamics investigations of the encapsulation of fullerene molecules in boron nitride nanotubes, a hybrid system with large potential for various materials applications.The cover picture shows possible positions for the diffusion of C60 into the BN nanotube. The light colored C60 (I–III) can be encapsulated in the tube. The yellow colored C60 (IV) with some atoms located above the tube wall, however, is quickly adsorbed and moves on the surface of the tube. The dark line hence indicates the border for diffusion.The corresponding author Ho Jung Hwang is Professor of Electrical and Electronic Engineering and Dean of the College of Engineering at Chung‐Ang University, Seoul, Korea. His main interests are in semiconductor technology, process/equipment simulation, nanotechnology, and nanosimulation.
Review of in situ remediation technologies for lead, zinc, and cadmium in soil
Authors: Martin Todd A. , Ruby Michael V. 
Published: June 2004

AbstractThis article presents a review of in situ technologies for the remediation of soils contaminated with lead, zinc, and/or cadmium. The objective of this review is to assess the developmental status of the available in situ technologies and provide a general summary of typical applications and limitations of these technologies. The literature review identified seven in situ remediation technologies—solidification/stabilization, vitrification, electrokinetic remediation, soil flushing, phytoextraction, phytostabilization, and chemical stabilization. These technologies were considered for their ability to meet a specific set of remediation objectives under a range of conditions. Each of these technologies has both strengths and weaknesses for addressing particular remedial situations discussed in the article for each of the technologies. A general summary of which technologies are most applicable to common remedial scenarios is also provided. © 2004 Wiley Periodicals, Inc.