bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Probing of Photochemical Reactions Inside Femtolitre Droplets Confined to Electrodes
Authors: Wadhawan Jay D. , Wain Andrew J. , Compton Richard G. 
Published: November 2003

AbstractRandom ensembles of femtolitre‐volume droplets containing redox active, photosensitive compounds immobilised on an electrode substrate permit photoelectrochemical studies within femtometric environments. Two chemical systems are described; the first is the N,N,N′,N′‐tetrahexyl‐para‐phenylenediamine redox‐catalysed photochemical debromination of the anaesthetic reagent halothane; the second is the photoinduced electron transfer from excited chlorophyll a to vitamin K1, which has possible potential in the development of solar cells based on photosynthesis.
Radical Ions from 3,3′′′,3′′′″‐Tris(butylsulfanyl)‐2,2′:5′,2″:5″,2′′′,5′′′,2′′′′:5′′′′,2′′′″‐sexithiophene: An Experimental and Theoretical Study of the p‐ and n‐Doped Oligomer
Authors: Alberti Angelo , Ballarin Barbara , Guerra Maurizio , Macciantelli Dante , Mucci Adele , Parenti Francesca , Schenetti Luisa , Seeber Renato , Zanardi Chiara 
Published: November 2003

AbstractThe 3,3′′′,3′′′″‐tris(butylsulfanyl)‐2,2′:5′,2″:5″,2′′′,5′′′,2′′′′:5′′′′,2′′′″‐sexithiophene 1 was investigated through spectroscopic (NMR, EPR, UV/Vis‐NIR), electrochemical, spectroelectrochemical and theoretical (DFT) studies. The charged species obtained upon its oxidation and reduction were characterised, showing that 1 can exist in at least five different oxidation states, that is, a neutral species, a radical cation, a dication, a radical anion, and a dianion. The long term stability of the radical cation 1+. was evidenced by the 1H NMR study in the presence of small quantities of trifluoroacetic acid (TFA). This approach allowed a comparison of the relative broadening of proton signals of 1, induced by the electron exchange process with traces of radical cation 1+., and the hfc (hyperfine coupling) constants obtained from the EPR study and DFT calculations. In the radical cation, all of the heterocyclic sulphur atoms are not significantly involved in the delocalisation of the unpaired electron, whereas the opposite holds for the radical anion. Time‐dependent DFT calculations reproduced well the wavelengths of the optical transitions observed in the spectroelectrochemical experiments for all the five oxidation states and support the formation of the dianion 12−.
Pressure assisted evolution of defects in silicon
Authors: Londos C. A. , Potsidi M. S. , Bak‐Misiuk J. , Misiuk A. , Emtsev V. V. 
Published: November 2003

AbstractThe effect of enhanced hydrostatic pressure following heat treatment on the evolution of point defects in neutron‐irradiated Czochralski‐grown silicon is investigated using infrared spectroscopy. The behavior of oxygen‐related defects, particularly of the VO and the VO2 centers, is mainly studied using samples subjected to heat treatment under hydrostatic pressure. It is observed that (1) pressure accelerates the annealing process of the VO defects and enhances the growth of the VO2 complexes and (2) the VO2 concentration is larger than expected from the corresponding decay of the VO defects. The faster decay of the VO defects is attributed to a pressure‐induced decrease of their migration energy. The larger VO2 concentration is also discussed. One possible explanation is that pressure stimulates an additional mechanism for the formation of the VO2 defects, which involves the reaction of oxygen dimers with vacancies. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical properties of Bi1.5ZnSb1.5O7 pyrochlore ceramics
Authors: Kayed T. S. , Mergen A. 
Published: November 2003

AbstractBi1.5ZnSb1.5O7 pyrochlore samples were prepared by solid state reaction method. They were examined by x‐ray diffraction and scanning electron microscopy. Single phase, belongs to the cubic pyrochlore structure, with a lattice parameter of 10.442 Å and grain size that varies from 16 to 20 μm was obtained. The electrical properties were measured at different temperatures in the range 15–330 K under different applied magnetic fields up 1.4 T. In our measurements for Hall coefficient, Hall resistivity, and mobility; we noticed an anomalous behavior at two temperatures (around 250 and 310 K) which was supported by the I‐V measurements (double transition of the slope of I‐V characteristics (β) at the same temperatures). This was discussed in terms of polarization phenomenon and mixed ionic‐electronic conduction. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A scheduling algorithm for packet delay differentiation
Authors: Mase Kenichi , Ohara Kazuhiro , Nogami Shinya , Karasawa Naoyuki 
Published: November 2003

AbstractA scheduling algorithm called queue length control is proposed to ensure different quality in each of the traffic flows at a network node. This algorithm determines the control parameters (average queue length and its standard deviation) for a queue in advance (and off‐line) by using the M/G/1 model based on the delay target of each queue and then schedules based on these control parameters for each queue. A simulation compares this algorithm to other algorithms and demonstrates that the delay target of each traffic flow could be achieved over a broad range. When the control parameters are determined, although the actual packet length distribution and the packet arrival distribution are assumed to be different, a certain level of performance can be achieved. In other words, the presence of superior robust control characteristics is demonstrated. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 87–97, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10008
A narrowband interference rejection technique for DS‐CDMA system
Authors: Kitano Toyokazu , Nabetani Toshihisa , Hara Shinsuke , Morinaga Norihiko 
Published: November 2003

AbstractDue to congestion in wireless frequency use, it is difficult to assign an independent frequency bandwidth to broadband wireless communication systems based on the DS‐CDMA (Direct Sequence Code Division Multiple Access) system. Therefore, operation of the DS‐CDMA system on the existing narrowband wireless system is contemplated. However, the interference of the transmitted power of the existing narrowband wireless system on the DS‐CDMA system has not been studied. There is a possibility that significant narrowband interference on the DS‐CDMA system may occur. In this paper, a narrowband interference rejection system in DS‐CDMA is proposed. By making use of prior information on the carrier frequency of the narrowband interference, a narrowband interference rejection process with little computational overhead is realized. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 74–86, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10076
A study on mutual coupling compensation method of array antennas
Authors: Inaba Takayuki , Sakamoto Teijiro , Miura Ryu , Oodo Masayuki , Araki Kiyomichi 
Published: November 2003

AbstractResearch and development have been carried out extensively on the MUSIC and ESPRIT algorithms, based on the eigenfunction expansion of the correlation matrix, for high‐resolution direction‐of‐arrival estimation using array antennas. A factor hindering the best performance of these high‐resolution algorithms in real array antennas is nonuniformity of the element patterns caused by element coupling in an array configuration. In this paper, it is assumed that the array antenna is operated in a single mode and that the initial deviations of the transmitted amplitude and phase of the feed system and errors such as interelement coupling can be represented by a single coupling matrix with complex elements. Under such assumptions, this paper proposes a method for compensating the error of the center of rotation of the rotating table on which the device under test for calibration data measurement is installed, and estimates the coupling matrix. By computer simulation in the case of a receiving array antenna, it is found that the coordinates of the rotating center and the coupling coefficient can be estimated and that received signals with the initial deviation and interelement coupling compensated can be obtained by multiplying by the inverse of the coupling matrix estimated for the received signals. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 59–73, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10126
An adaptive media access control protocol and system performance of wireless ad hoc network using smart antenna
Authors: Ueda Tetsuro , Bandyopadhyay Somprakash , Hasuike Kazuo 
Published: November 2003

AbstractA smart antenna can increase the number of simultaneous transmissions by reducing interference and improving the throughput performance. In this paper, we propose an adaptive media access control (MAC) protocol that periodically updates neighboring node information in a distributed network, such as a wireless ad hoc network, and uses smart antennas to achieve simultaneous communications by directionality control to neighboring nodes other than those currently communicating. We also verify that the overhead for updating the neighboring node information can be reduced to 15% or less than in conventional schemes and the number of simultaneous communications can be 2 to 3.5 times higher than when using omnidirectional antennas. Furthermore, we considered the effects of the overhead accompanying neighboring node updates, node density, beam width, and moving speed on the communication efficiency when using the proposed MAC protocol. The communication efficiency was improved by controlling the transmission power to shorten the transmission range, lower the node density, and widen the beam width more than by extending the transmission range and increasing the node density. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 50–58, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10140
Analysis of radial line slot antennas with dielectric layers over the aperture
Authors: Miyachi Kensuke , Hirokawa Jiro , Ando Makoto 
Published: November 2003

AbstractThe slot coupling characteristics are analyzed and the aperture distributions are evaluated for several dielectric layers loaded on the upper surface outside the radial line slot antenna. First, for the design of a uniform aperture distribution, mutual coupling is expressed approximately by an infinite array of two‐dimensional slot pairs with equal‐amplitude excitation in a model with periodic boundary walls in the two directions of an external region. Based on this approximation, the slot length and the pair spacing in the radial direction are controlled so as to design an array with a uniform aperture distribution. Next, as a model effective for an arbitrary distribution over a finite aperture, a slot array that is finite in one dimension is analyzed by the spectral domain approach. Also, if the situation with dielectric loading through a gap such as a radome is considered, it is shown that the effect on the aperture distribution can be neglected if a dielectric layer with a thickness reducing the Fresnel reflection coefficient is placed about 1/8 wavelength away. The validity of the analysis and design is confirmed by trial fabrication and measurement at 38 GHz. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 19–27, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10169
Error rate performance of multiple‐symbol differential detection over transmission channels with nonlinear amplification
Authors: Handa Shiro , Katase Yasuyuki , Sasamori Fumihito , Oshita Shinjiro 
Published: November 2003

AbstractWhen efficient power amplification is considered in digital wireless communications, even the nonlinear region of an amplifier is used. In such cases, the symbol error rate deteriorates due to AM‐AM and AM‐PM distortion. This paper studies the spectral expansion, intersymbol interference, and symbol error rate when a nonlinear amplifier is used for transmission in a multivalued amplitude and phase modulation scheme. Multiple‐symbol differential detection using the RLS (Recursive Least Squares) algorithm is compared with coherent detection in order to eliminate the effect of nonlinear amplification and fading. The transmission characteristics when these detection methods are applied to transmission of the star QAM scheme in a white Gaussian noise channel and a Rayleigh fading channel are studied. It is confirmed that multiple‐symbol differential detection provides better symbol error rates than coherent detection. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 1–10, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10183
Signal extension for orthogonal filter banks and its application to image coding
Authors: Uto Toshiyuki , Inoue Tomoya , Ikehara Masaaki 
Published: November 2003

AbstractIn this paper, a signal extension method is proposed for realization of nonextension convolution in a two‐channel orthogonal FIR filter bank. Methods of performing nonextension convolution include the symmetric extension method for a linear phase filter bank and the periodic extension method applicable to an arbitrary filter bank. However, the periodic extension method is not appropriate for image compression because it becomes discontinuous at the signal edge. In this paper, for application to an orthogonal filter bank, the input signal of the decomposed filter bank is extended in such a way that the input signal in the synthesized filter bank has symmetry similar to that in the symmetric extension method. In this way, nonextension convolution is realized. In this case, it is shown that there are degrees of freedom in the extension signals determined by the input signal and the coefficients of the decomposed filter bank. The extended signal is calculated by singularity decomposition in such a way that the extended signal becomes smooth. Finally, the proposed method is applied to the coding of static images and the effectiveness of the method is demonstrated. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 41–48, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10125
Bifurcation structure of fractional harmonic entrainments in the forced Rayleigh oscillator
Authors: Sekikawa Munehisa , Inaba Naohiko , Yoshinaga Tetsuya , Kawakami Hiroshi 
Published: November 2003

AbstractThe bifurcation structure of fractional harmonic entrainments in the forced Rayleigh equation is analyzed in connection with the symmetry of the system. Due to the symmetry of the system, there are two types of fractional harmonic entrainment regions. One is the case in which an attractor symmetric in shape with respect to the origin is generated in the state space. Another is the case in which two attractors in an asymmetric shape appear in locations symmetric with respect to the origin. When the shapes of these bifurcation structures are studied on the parameter surface, it is found that the fractional harmonic entrainment regions of the two cases have different structures near the Neimark–Sacker bifurcation curve of the fundamental harmonic periodic solutions. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 30–40, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10126
Constrained blind equalizer using adaptive nonlinear filter
Authors: Koizumi Ryo , Miyajima Teruyuki , Yamanaka Kazuo 
Published: November 2003

AbstractIn this paper, a new adaptive equalizer that adjusts the nonlinear filter without training signals is proposed and its performance is evaluated. In the proposed equalizer, the nonlinear filter has constraints, while learning is carried out by means of the output energy minimization algorithm. Since the proposed equalizer has nonlinearity, it has a better bit error rate than the linear equalizer. Further, since no training signal is needed, it is to be expected that the transmission efficiency is superior to that in an equalizer with training signals. In order to evaluate the performance limitations of the proposed equalizer, an optimum equalizer with constrained filter input is derived. By means of simulations, a performance evaluation is carried out and the effectiveness of the proposed equalizer is demonstrated. Further, in order to improve the performance of the proposed equalizer for a linear communication channel, an intersymbol interference canceler and an algorithm for correcting the error are proposed and their effectiveness is demonstrated. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 17–29, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10145
A realization of transconductors based on an exponential circuit
Authors: Ishibashi Yukio , Hayashi Yugo , Ito Daisuke 
Published: November 2003

AbstractThis paper presents a transconductor configuration method based on an exponential circuit. First, the transconductor circuit configuration of the proposed method is described and its parameter values are presented, along with their theoretical transconductance values. Each parameter value in the proposed circuit can easily be derived by Taylor expansion of the output current. In this way, it is shown that the theoretical values of the linear input range of the proposed circuit are wider than those in the conventional cases. Next, a method of realization of the gain factor is described. Finally, the proposed method is confirmed by SPICE simulation. It is shown that the linear input range is close to the theoretical value. In addition, the total harmonic distortion (THD) and the noise characteristics are measured. Specifically, the proposed transconductor is shown to have good performance in noise. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 10–16, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10146
q‐ary asymmetric error locating codes under the directional error model
Authors: Kiattichai Saowapa , Kaneko Haruhiko , Fujiwara Eiji 
Published: November 2003

AbstractCharacter recognition systems, which employ a machine to recognize handwritten or printed characters, are prone to recognition errors in the cases of characters which are similar in shape. For example, the numerical character 7 is frequently mistaken for 9, and vice versa. In contrast, the characters 7 and 4 are not similar in shape, and 7 is unlikely to be mistaken for 4, or vice versa. Therefore, the rate of recognition error between these characters will be low. By considering this type of error model, this paper defines a new q‐ary asymmetric error and proposes a method for constructing single q‐ary asymmetric error locating codes. It also presents an evaluation of the code, demonstrating its superiority to the conventional single q‐ary symmetric error correcting code. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 77–87, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1156
Mechanism of Reduction of 2,2‐Dibromomethyl‐1,3‐propanediol by NiI‐Tetraazamacrocyclic Complexes in Aqueous Solution − A Pulse Radiolysis and Electrochemical Study
Authors: Shandalov Elisabetha , Zilbermann Israel , Maimon Eric , Nahmani Yeoshua , Cohen Haim , Adar Eilon , Meyerstein Dan 
Published: November 2003

AbstractThe reduction, catalytic reduction and the electrocatalytic reduction of halo‐organic compounds are of major interest due to their role as pollutants. The mechanism and kinetics of reduction of 2,2‐dibromomethyl‐1,3‐propanediol by several NiI tetraazamacrocyclic complexes, (NiILi)+ (i = 1−4), in aqueous solutions to yield Br− and the non‐halogenated compound was studied using the pulse radiolysis technique. The rate constants k = 5.3 × 108, 1.6 × 107, 6.0 × 105 and 3.5 × 104 M−1s−1 for L1, L2, L3 and L4 respectively, of the reactions (NiILi)+ + RBr ⇄ (NiIILi)2+ + Br− + R· increase with the free‐energy gain in the reaction. All these complexes are good electrocatalysts for the reduction of this substrate. The mechanisms of the reductions is are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A New Diazacyclooctane Dihydroxamate as a Siderophore Analogue − Synthesis and Equilibrium Studies of Iron(III) and Copper(II) Complexes
Authors: Gaspar Margarida , Telo J. Paulo , Santos M. Amélia 
Published: November 2003

AbstractA new siderophore analogue based on the mesocyclic diamine 1,5‐diazacyclooctane (DACO) functionalized with two additional hydroxamate donor pendant groups, 1,5‐diazacyclooctane‐1,5‐bis(N‐methylacetohydroxamic acid) (DACODMAHA), has been synthesized from the corresponding diacetate derivative (DACODA). The complexation behaviour of this ligand towards CuII and FeIII in aqueous solution has been studied by potentiometry, UV/Vis and EPR spectroscopy and magnetic moment measurements. The CuII complexation involves the formation of a mononuclear species with a tetradentate mixed amine/hydroxamate coordination mode, whereas the FeIII complexation involves a binuclear species with Fe2L3 stoichiometry and normal {O,O}‐hydroxamate coordination mode. The redox potential of the iron complexes and the corresponding electron transfer mechanism are also evaluated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Design of Calixarene‐Type Ligands for Second Sphere Complexation of Noble Metal Ions
Authors: Belhamel Kamel , Nguyen T. K. Dzung , Benamor Mohamed , Ludwig Rainer 
Published: November 2003

AbstractMacrocyclic ligands were designed according to the principle of ion recognition, synthesized and tested in their capability to extract AuIII. Different from other complexants which require ligand exchange prior to complexation, the reported ligands bind the complexes AuCl3 and AuCl4−. With a sufficiently sized macrocyclic cavity, hydrophobic calix[6]arenes derivatized at the “lower rim’ were employed for that purpose. Their ligating functionalities contain pyridino, amide or thioamide groups in order to achieve electron donor‐acceptor and electrostatic host‐guest interactions. We report the synthesis route and results on extraction, selectivity, kinetics and back‐extraction and compare with commercial extractants. Quantitative extraction from hydrochloric acid solutions was achieved as well as over 99% recovery in back‐extraction in one step each. Data on the selectivity over base metals, which are representative for the matrix in gold ores are provided. The ligands are powerful extractants for AuIII and show fast complexation kinetics. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Preparation, Photo‐luminescence and Electro‐Luminescence Behavior of Langmuir−Blodgett Films of Bipyridylrhenium(I) Surfactant Complexes
Authors: Yam Vivian Wing‐Wah , Li Bin , Yang Yu , Chu Ben Wai‐Kin , Wong Keith Man‐Chung , Cheung Kung‐Kai 
Published: November 2003

AbstractSeveral bipyridylrhenium(I) surfactant complexes, fac‐[Re(CO)3(bpy)(L)]PF6 [bpy = 2,2′‐bipyridine, L = trans‐4‐dodecyloxy‐4′‐stilbazole (L1), trans‐4‐octadecyloxy‐4′‐stilbazole (L2), 4‐(4′‐dodecyloxyphenylethynyl)pyridine (L3)] were synthesized and characterised. The X‐ray crystal structure of fac‐[Re(CO)3(bpy)(L1)]PF6 has been determined. The complexes exhibited intense photo‐luminescence which has been ascribed to the dπ(Re) ⇄ π*(bpy) metal‐to‐ligand charge transfer (MLCT) triplet emission. The complexes were found to form stable Langmuir−Blodgett (LB) films with relatively high collapse pressures. The organic light‐emitting diodes (OLEDs) fabricated by employing the LB films of various complexes as the emitting layer exhibited electroluminescence (EL) behavior. The luminances of the EL devices were found to vary as a function of the number of LB film layers, hydrocarbon chain length and the deposition types. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)