bluuebunny/crossref_metadata_2025 huggingface dataset:
Social‐developmental factors affecting lesbian and gay youth: a review of cross‐national research findings
Authors: Rivers Ian , Carragher Daniel J.
Published: November 2003

Lesbian and gay youth face a great many challenges as they grow up. In this article, research focusing upon the social‐developmental factors that affect the positive development of a lesbian or gay identity are reviewed, comparing and contrasting data from the United States (US) and United Kingdom (UK). Consideration is also given to the efficacy of behaviours utilised by young lesbians and gay men to avoid harassment and discrimination. It is suggested that lesbian and gay youth represent a particularly vulnerable group of young people who engage in a number of health risk behaviours that are associated not only with sexual orientation, but also fears for personal safety. Finally the authors discuss whether or not strategies to conceal sexual orientation hold benefits for lesbian and gay youth in terms of their physical safety and mental health. Copyright © 2003 John Wiley & Sons, Ltd.
Polymeranaloge Umsetzung von Poly(butadien‐co‐acrylnitril) mit 2‐Aminoalkoholen in Lösung und in der Schmelze
Authors: Pankow O. , Schmidt‐Naake G.
Published: November 2003

No abstracts.
Charakterisierung der Porosität von Schülpen: Stanzmethode und NIRS‐Methode
Authors: Wöll F. , Kleinebudde P.
Published: November 2003

No abstracts.
Untersuchungen zum Dämpfungsverhalten hochdisperser, kohäsiver Pulver
Authors: Haack A. , Tomas J.
Published: November 2003

No abstracts.
HPDS‐Hochdruckzelle zur Beobachtung mikroskopischer Phänomene unter Hochdruck
Authors: Hartmann M. , Pfeifer F. , Dornheim G. , Sommer K.
Published: November 2003

No abstracts.
Chancen und Grenzen der Mikroverkapselung in der modernen Lebensmittelverarbeitung
Authors: Kunz B. , Krückeberg S. , Weißbrodt J.
Published: November 2003

Die Mikroverkapselung ist in der Lebensmittelindustrie immer bedeutender geworden, besonders im Bereich der funktionellen Lebensmittel und der Nahrungsergänzungsmittel. Die Verkapselung dient dem Schutz des eingeschlossenen Materials vor schädlichen Einflüssen. Das Verfahren birgt ein großes Potenzial für die Entwicklung neuer Produkte. Der Einschluss von ernährungsphysiologisch positiv zu bewertenden Substanzen führt zu Produkten mit einem zusätzlichen gesundheitlichen Nutzen (Added Value). Obwohl die Mikroverkapselung sich erst am Anfang ihrer Entwicklung befindet, ist es sinnvoll, die Chancen und Risiken dieser vielversprechenden Technologie abzuschätzen. Der Beitrag gibt einen Überblick über die Möglichkeiten der Mikroverkapselung in der Lebensmittelindustrie und zeigt zugleich die Grenzen der neuen Technologie auf.
QM/MM Car‐Parrinello Molecular Dynamics Study of the Solvent Effects on the Ground State and on the First Excited Singlet State of Acetone in Water
Authors: Röhrig Ute F. , Frank Irmgard , Hutter Jürg , Laio Alessandro , VandeVondele Joost , Rothlisberger Ursula
Published: November 2003

We present a hybrid Car–Parrinello quantum mechanical/molecular mechanical (QM/MM) approach that is capable of treating the dynamics of molecular systems in electronically excited states in complex environments. The potential energy surface in the excited state is described either within the restricted open‐shell Kohn–Sham (ROKS) formalism or within time‐dependent density functional theory (TDDFT). As a test case, we apply this technique to the study of the solvent effects on the ground state and on the first excited singlet state of acetone in water. Our results demonstrate that for this system a purely classical description of the solvent is sufficient, since inclusion of the first solvent shell of 12 water molecules into the quantum system does not show a significant effect on this transition. The excited‐state energies calculated with ROKS are red shifted by a constant value compared to the TDDFT results, while the relative variations of the excitation energy for different configurations are in very good agreement. The experimentally observed blue shift of the excitation energy in going from gas phase to condensed phase is well reproduced. Excited‐state dynamics carried out with ROKS yield the relaxation of the solute and the rearrangement of the solvent structure on a picosecond timescale. The calculated Stokes shift is in reasonable agreement with experimental data.
Nanotubes à la Carte: Wetting of Porous Templates
Authors: Steinhart Martin , Wendorff Joachim H. , Wehrspohn Ralf B.
Published: November 2003

Nanotubes have an outstanding potential both for applications in nanotechnology and as the subject of basic research. Wetting of porous templates is a simple technique that overcomes many limitations of established preparation methods. It extends the range of processable materials, for example, by a broad range of multicomponent mixtures or by high‐performance polymers such as poly(oxy‐1,4‐phenyleneoxy‐1,4‐phenylenecarbonyl‐1,4‐phenylene) (PEEK) and polytetrafluoroethylene (PTFE). Inducing controlled phase transitions generates a large specific surface, a specific nanoporosity, or oriented crystalline domains within the nanotube walls. Template wetting provides customized nanotubes and allows us to investigate how the wall curvature affects the structure formation.
Aligned Nanotubes
Authors: Dai Liming , Patil Ajeeta , Gong Xiaoyi , Guo Zhixin , Liu Luqi , Liu Yong , Zhu Daoben
Published: November 2003

Since the discovery of carbon nanotubes by Iijima in 1991, various carbon nanotubes with either a single‐ or multilayered graphene cylinder(s) have been produced, along with their noncarbon counterparts (for example, inorganic and polymer nanotubes). These nanostructured materials often possess size‐dependent properties and show new phenomena related to the nanosize confinement of the charge carriers inside, which leads to the possibility of developing new materials with useful properties and advanced devices with desirable features for a wide range of applications. In particular, carbon nanotubes have been shown to exhibit superior properties attractive for various potential applications, ranging from their use as novel electron emitters in flat‐panel displays to electrodes in electrochemical sensors. For many of the applications, it is highly desirable to have aligned/patterned forms of carbon nanotubes so that their structure/property can be easily assessed and so that they can be effectively incorporated into devices. In this Review, we present an overview on the development of aligned and micropatterned nanotubes, with an emphasis on carbon nanotubes.
Topological and Electron‐Transfer Properties of Yeast Cytochrome c Adsorbed on Bare Gold Electrodes
Authors: Bonanni Beatrice , Alliata Dario , Bizzarri Anna Rita , Cannistraro Salvatore
Published: November 2003

The redox metalloprotein yeast cytochrome c was directly self‐chemisorbed on “bare” gold electrodes through the free sulfur‐containing group Cys102. Topological, spectroscopic, and electron transfer properties of the immobilised molecules were investigated by in situ scanning probe microscopy and cyclic voltammetry. Atomic force and scanning tunnelling microscopy revealed individual protein molecules adsorbed on the gold substrate, with no evidence of aggregates. The adsorbed proteins appear to be firmly bound to gold and display dimensions in good agreement with crystallographic data. Cyclic voltammetric analysis showed that up to 84 % of the electrode surface is functionalised with electroactive proteins whose measured redox midpoint potential is in good agreement with the formal potential. Our results clearly indicate that this variant of cytochrome c is adsorbed on bare gold electrodes with preservation of morphological properties and redox functionality.
A Combined Atomic Force Microscopy and Molecular Dynamics Simulation Study on a Plastocyanin Mutant Chemisorbed on a Gold Surface
Authors: Bizzarri Anna Rita , Bonanni Beatrice , Costantini Giulio , Cannistraro Salvatore
Published: November 2003

A mutant of copper plastocyanin, covalently bound to an Au (111) surface through an engineered disulfide bridge, was investigated in aqueous medium by atomic force microscopy (AFM) and molecular dynamics (MD) simulations. Tapping‐mode AFM images revealed adsorption of single molecules which are homogeneously distributed over the substrate and strongly bound to gold and display uniform lateral size. A statistical analysis of the height of the macromolecules on the gold substrate evidenced a distribution around a mean value consistent with that expected from the crystallographic data and with a relatively large standard deviation. A 10‐ns classical MD simulation of mutated plastocyanin, hydrated by a layer of water, covalently bound to a gold surface by one or two sulfur atoms, was performed. The simulations indicate that the bound protein retains, in both cases, its overall tertiary structure during the dynamic evolution. Moreover, the macromolecule can assume different orientations with respect to the gold substrate, which give rise to a distribution of heights on the gold substrate. Experimental and MD simulation results are compared and discussed in connection with the topological and dynamical properties of the protein system.
A High‐speed Atomic Force Microscope for Studying Biological Macromolecules in Action
Authors: Ando Toshio , Kodera Noriyuki , Naito Yasuyuki , Kinoshita Tatsuya , Furuta Ken'ya , Toyoshima Yoko Y.
Published: November 2003

The atomic force microscope (AFM), which was invented by Binnig et al. in 1986, can image at nanometer resolution individual biological macromolecules on a substrate in solution. This unique capability awoke an expectation of imaging processes occurring in biological macromolecules at work. However, this expectation was not met, because the imaging rate with available AFMs was too low to capture biological processes. This expectation has at last been realized by the high‐speed AFM developed by our research group at Kanazawa University. In this article, after a brief review of the development of our apparatus, its recent advancement and imaging data obtained with motor proteins are presented.
Cover Picture: QM/MM Car‐Parrinello Molecular Dynamics Study of the Solvent Effects on the Ground State and on the First Excited Singlet State of Acetone in Water (ChemPhysChem 11/2003)
Authors: Röhrig Ute F. , Frank Irmgard , Hutter Jürg , Laio Alessandro , VandeVondele Joost , Rothlisberger Ursula
Published: November 2003

The cover picture shows…︁‥the solvent effect of water upon the lowest‐lying singlet excitation in acetone. The transition, which involves the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), is blue‐shifted in water (sol) with respect to the gas phase (vac), since the HOMO is stronger stabilized in water than the LUMO. The authors calculate the absorption and fluorescence spectra of acetone in water with a hybrid Car–Parrinello quantum chemical/classical molecular dynamics approach and investigate the influence of the solvent. The lower part of the picture shows the excitation energy during a simulation. One configuration with a very high excitation energy (three hydrogen bonds, short CO bond) and one configuration with a very low excitation energy (two hydrogen bonds, long CO bond) are shown in detail. Find out more in the article by Rothlisberger and co‐workers on pages pp. 1177–1182.
Czochralski growth and constitutional studies on single crystals of potassium lithium niobate (KLN)
Authors: Podlojenov S. , Burianek M. , Mühlberg M.
Published: November 2003

The ferroelectric phase of potassium lithium niobate K3Li2−xNb5+xO15 (KLN) is a very promising material for the conversion of infrared light to light in the visible region. However, growing of single crystals is known to be complicated due to the considerable anisotropy of the growth rate and the thermal expansion behaviour. The single crystals of KLN, Mg2+‐doped KLN, as well as the mixed crystals of potassium lithium tantalate niobate K3Li2(Nb1−xTax)5O15 (KLTN) were grown by the Czochralski technique. The chemical analyses of the samples were performed by atomic absorption spectroscopy (AAS) and X‐ray fluorescence analysis (XRF). The element concentrations along the single crystals were measured by the electron microprobe analysis (EMPA) to clarify the segregation phenomena in the grown crystals. The elements distribution coefficients were also calculated. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local 3D real space atomic structure of the simple icosahedral Ho11Mg15Zn74 quasicrystal from PDF data
Authors: Brühne S. , Uhrig E. , Gross C. , Assmus W.
Published: November 2003

We present a new complementary strategy to quasicrystalline structure determination: The local atomic structure of simple icosahedral (si) Ho11Mg15Zn74 [a(6D) = 5.144(3)Å in a sphere of up to r = 17Å was refined using the atomic pair distribution function (PDF) from in‐house X‐ray powder diffraction data (MoKα1, Qmax = 13.5Å−1; R = 20.4%). The basic building block is a 105‐atom Bergman‐Cluster {Ho8Mg12Zn85}. Its center is occupied by a Zn atom – in contrast to a void in face centred icosahedral (fci) Ho9Mg26Zn65. The center is then surrounded by another 12 Zn atoms, forming an icosahedron (1st shell). The 2nd shell is made up of 8 Ho atoms arranged on the vertices of a cube which in turn is completed to a pentagon dodecahedron by 12 Mg atoms, the dodecahedron then being capped by 12 Zn atoms. The 3rd shell is a distorted soccer ball of 60 Zn atoms, reflecting the higher Zn content of the si phase compared to the fci phase. In our model, 7% of all atoms are situated in between the clusters. The model corresponds to a hypothetical 1/1‐approximant of the icosahedral (i) phase. The local coordinations of the single atoms are of a much distorted Frank‐Kasper type and call to mind those present in 0/1‐Mg2Zn11. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A comparative study for profiling ultrathin boron layers in Si
Authors: Basaran E. , Addemir O. , Aslan M. H. , Parker E. H. C.
Published: November 2003

The carrier concentration‐depth profiles of ultrathin boron layers in Si, grown by molecular beam epitaxy, are determined by the electrochemical capacitance‐voltage (ECV) and the spreading resistance (SR) profiling techniques. Secondary ion mass spectrometry (SIMS) is employed as a base for the comparison of the results. It has been shown that, under carefully chosen conditions, both ECV and SR techniques are able to resolve ultrathin layers including a delta layer, however ECV match better with the results of SIMS than that of SR. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies on zirconium nitride films deposited by reactive magnetron sputtering
Authors: Bhuvaneswari H. B. , Nithiya Priya I. , Chandramani R. , Rajagopal Reddy V. , Mohan Rao G.
Published: November 2003

This paper deals with the preparation of Zirconium Nitride films by DC reactive magnetron sputtering. Films were deposited on silicon substrates at room temperature. Nitrogen partial pressure was varied from 4 × 10−5 to 10 × 10−5 m bar and the effect on the structural, electrical, optical properties of the films was systematically studied. The films formed at a nitrogen pressure of 6 × 10−5 mbar showed low electrical resistivity of 1.726 × 10−3 Ω.cm. The deposited films were found to be crystalline with refractive index and extinction coefficient 1.95 and 0.4352 respectively. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoelectronic and electrical properties of CuIn5S8 single crystals
Authors: Qasrawi A. F. , Gasanly N. M.
Published: November 2003

To identify the impurity levels in CuIn5S8 single crystals, the dark electrical conductivity and photoconductivity measurements were carried out in the temperature range of 50–460 K. The data reflect the intrinsic and extrinsic nature of the crystals above and below 300 K, respectively. Energy band gaps of 1.35 and 1.31 eV at 0 K and 300 K, were defined from the dark conductivity measurements and the photocurrent spectra, respectively. The dark and photoconductivity data in the extrinsic temperature region reflect the existence of two independent donor energy levels located at 130 and 16 meV. The photocurrent‐illumination intensity dependence (F) follows the law IphαFγ, with γ being 1.0, 0.5 and 1.0 at low, moderate and high intensities indicating the domination of monomolecular, bimolecular and strong recombination at the surface, respectively. In the intrinsic region and in the temperature region where the shallow donor energy level 16 meV is dominant, the free electron life time, τn, is found to be constant with increasing F. In the temperature region 140 K < T < 210 K, the free electron life time increases with increasing illumination intensity showing the supralinear character. Below 140 K, τn decrease with decreasing illumination intensity. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Annealing effect on electrical and photoconductive properties of Si implanted GaSe single crystal
Authors: Karabulut O. , Parlak M. , Yilmaz K. , Turan R. , Akinoglu B. G.
Published: November 2003

GaSe single crystals grown by Bridgman method have been doped by ion implantation technique. The samples were bombarded in the direction parallel to c‐axis by Si ion beam of about 100 keV to doses of 1 × 1016 ions/cm2 at room temperature. The effects of Si implantation with annealing at 500 and 600 °C on the electrical properties have been studied by measuring the temperature dependent conductivity and photoconductivity under different illumination intensities in the temperature range of 100–320 K. It is observed that Si implantation increases the room temperature conductivity 10−7 to 10−3 (Ω‐cm)−1 depending on the post annealing temperature. The analysis of temperature dependent conductivity shows that at high temperature region above 200 K, the transport mechanism is dominated by thermal excitation in the doped and undoped GaSe samples. At lower temperatures, the conduction of carriers is dominated by variable range hopping mechanism in the implanted samples. Annealing of the samples at and above 600 °C weakens the temperature dependence of the conductivity and photoconductivity. This indicates that annealing of the implanted samples activates Si‐atoms and increases structural deformations and stacking faults. The same behavior was observed from photoconductivity measurements. Hence, photocurrent‐illumination intensity dependence in the implanted samples obeys the power low Ipc ∝ Φn with n between 1 and 2 which is an indication of continuous distribution of localized states in the band gap. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Misleading fringes in TEM images and diffraction patterns of Si nanocrystallites
Authors: Kohno Hideo , Ozaki Nobuhiko , Yoshida Hideto , Tanaka Koji , Takeda Seiji
Published: November 2003

High‐resolution transmission electron microscopy (HRTEM) images and electron diffraction patterns of twinned Si nanocrystallites were recorded along various directions and analyzed in detail. We point out that special attention must be paid when interpreting HRTEM images and diffraction patterns of twinned Si nanocrystallites, because elongation of reciprocal lattice points could fabricate misleading fringes and patterns. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and spectra character of cobalt nickel sulfate twelvehydrate (CNSH) single crystal
Authors: Su Genbo , Zhuang Xinxin , He Youping , Li Zhengdong , Li Guohui , Ma Jingbo , Wang Guofu , Huang Zixiang
Published: November 2003

The title compound CoNi(SO4)2 · 12H2O has been prepared and its crystal structure determined by single crystal X‐ray differaction at room temperature. The CNSH crystal structure belongs to the monoclinic space group C2/c,a = 9.966(2) Å, b = 7.2265(14) Å, c = 24.218(5) Å, β = 98.32(3)°, V = 1725.9(6) Å3, z = 4, Dc = 2.024 gcm−3. The optical transmission character of CNSH crystal in aqueous solution is discontinuous in the range from ultraviolet to near IR wavelengths. The relationship between the structure and the optical transmission property is further discussed. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Design on quasi‐Yagi antennas array based on genetic algorithm
Authors: Kojiya Takuya , Tsuji Yosuke , Kuwahara Yoshihiko
Published: November 2003

As radiating elements for a phased array consisting of radiating elements placed along a straight line, a quasi‐Yagi antenna that has a reflector behind the dipole and a parasitic element in front is used. The length of the parasitic elements and the distance between the parasitic element and the dipole are optimized by the genetic algorithm in such a way that the gain deterioration due to beam scanning is the minimum. Further, the quasi‐Yagi antenna is applied in the array antenna for direction‐of‐arrival estimation using such subarrays as ESPRIT. The parameters optimizing the direction‐of‐arrival estimation accuracy are derived by the genetic algorithm. The array antenna with quasi‐Yagi antenna optimized by the genetic algorithm can significantly improve the beam scanning characteristics and improve the accuracy and resolution when used for direction‐of‐arrival estimation by ESPRIT. This is confirmed by computer simulation and test evaluation. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 39–49, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10158
Adaptive reliable multicast using TCP protocol in heterogeneous environments
Authors: Takenaka Toyofumi , Sasaki Hiroaki
Published: November 2003

An attempt is made to realize highly reliable multicast communications without modifying the TCP protocol, which is now the most widely used in the Internet, and TCP multicast using a GRA (generic router assist) router is proposed. The characteristics of this multicast communications are evaluated, and it is shown that the overall throughput of multicast communications is governed by the bottleneck link in the transmission band. An attempt is made to improve the performance of multicast communications with a bottleneck link, and an environment‐adaptive multicast communication scheme is proposed, in which the multicast tree is partitioned at the bottleneck link, and TCP multicasting is performed for each subtree. Performance evaluation by simulation shows that the proposed method alleviates the effect of the bottleneck link on the overall multicast and that the performance of the multicast as a whole can be improved. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 28–38, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10161
An adaptive sidelobe cancellation algorithm for high‐gain antenna arrays
Authors: Kamio Kazunori , Sato Toru
Published: November 2003

In order to more accurately extract desired signals, it is necessary to suppress interference such as reflection and clutter more strictly. This paper discusses a method of suppressing sidelobes adaptively by placing a receive‐only array around a high‐gain array. The output power minimization method (DCMP) has been proposed as an adaptive clutter suppression method. When this method is applied to a high‐gain array, there is a danger of destroying the directivity of the high‐gain array. In this paper, a constraint on the weight not destroying the receiving pattern of the high‐gain array is added to the DCMP, resulting in a norm‐constrained DCMP (DCMP‐CN). By using this method, adaptive sidelobe suppression is possible regardless of the intensity of the input signals. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 11–18, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10178
An analysis on the critical phenomena in CSMA/CD network traffic model by computer simulations
Authors: Takeshima Yoshiteru , Fukuda Kensuke , Takayasu Hideki , Takayasu Misako
Published: November 2003

This paper considers a network with CSMA/CD access and shows by computer simulation that phase transitions can accompany critical phenomena in the traffic flowing in the media. It is also shown that the relation between the buffer size that maximizes the network throughput and the back‐off limit can be approximately formulated. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(3): 98–106, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1187
An interactive fuzzy satisficing method based on a probability maximization model for multiobjective linear programming problems involving random variable coefficients
Authors: Kato Kosuke , Sakawa Masatoshi , Katagiri Hideki , Wasada Kouichi
Published: November 2003

As an approach to the optimization of systems containing fuzziness and uncertainty, the probabilistic programming method including uncertainty based on probability theory and the fuzzy mathematical programming method representing fuzziness in terms of fuzzy theory are typical ones that have been developed in various forms. In the present research, we target multiobjective linear programming problems in which the coefficients included in the program are random variables. We develop a formulation based on the probabilistic maximization model in which the probability that several objective functions are below certain values is maximized under the stochastic constraint condition that the constraints need not be satisfied all the time but only above a certain probability. For the multiobjective probability maximization model, the fuzzy target of the decision maker is introduced. Also, an interactive algorithm based on the reference point method that derives a solution satisfactory to the decision maker by interaction with the decision maker is applied. The new decision making process is a combination of the probabilistic programming method and the fuzzy programming method. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 67–76, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10080
On simulations of self‐reproducing cellular automata with shape‐encoding mechanism
Authors: Imai Katsunobu , Hori Takahiro , Matsuda Yukio , Fujita Kenji , Morita Kenichi
Published: November 2003

We have designed self‐reproducing cellular automata based on two‐ and three‐dimensional self‐inspection, and emphasized the importance of simulating the intercellular transitions during the design phase. In particular, to understand the behavior in three dimensions, viewing the video image is essential. In this paper, we present videos generated by a simulation tool we built and demonstrate the operation according to the designs of previously designed self‐reproducing cellular automata. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 58–66, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10083
Complex Chebyshev approximation for FIR filters using linear semi‐infinite programming method
Authors: Suyama Kenji , Takada Ken'ichi , Hirabayashi Ryuichi , Iwakura Hiroshi
Published: November 2003

In the optimum design of an FIR filter by the complex Chebyshev method, it is difficult to limit the increase of computational effort and to guarantee convergence to an optimum solution due to the nonlinearity of the problem and the instability of the frequency points for the optima. In this paper, the complex Chebyshev approximation problem is formulated as a linear semi‐infinite programming problem by means of the real rotation theorem. An optimum design method is proposed using the three‐phase method, a linear semi‐infinite programming method. In the present method, the design problem is first reduced to a linear programming problem with constraints and a provisional solution is derived by the simplex method. After the constraints corresponding to the degenerated optimum frequencies contained in the provisional solution are combined, the solutions are adjusted to satisfy the optimum condition so as to obtain an optimum solution. Since low accuracy is sufficient for the provisional solution, memory requirements and computational effort can be reduced. By means of a design example, it is shown that the proposed method is superior in terms of solution accuracy and computational effort to the technique based on the simplex method. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 49–57, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10104
An automatic design method for compact acoustic systems by the genetic algorithm
Authors: Nakatani Takuya , Kajikawa Yoshinobu , Nomura Yasuo
Published: November 2003

In this paper, an automatic method for the design of compact acoustic systems, using the genetic algorithm, is proposed for improvement of degraded sensitivity caused by leakage. In the present method, an analysis based on the acoustic equivalent circuit is used. The equivalent circuit and the acoustic parameters of the circuit are designed in such a way that the sound pressure frequency characteristics are contained with the range based on the GSM (ETSI EN 300 903) specifications and that the sensitivity deterioration is improved. The PfGA (Parameter‐free Genetic Algorithm) is used in the design of the circuit configuration, and the genetic algorithm of Michalewicz is used for the design of acoustic parameters. As a result, an equivalent circuit is obtained that realizes characteristics not significantly affected by leakage. The present method can be applied to various compact acoustic systems such as cellular phones and provides useful information for actual design. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(3): 1–9, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10149
Synthesis and Structures of FeIII Complexes Bridged by Cyanorhenium Clusters
Authors: Park Seon‐Mi , Kim Youngmee , Kim Sung‐Jin
Published: November 2003

The reaction of FeCl(L1) and FeCl(L2) [L1 = bis(3‐salicylideneaminopropyl)amine, L2 = bis(3‐salicylideneaminopropyl)methylamine] with the Re6 clusters [Re6Q8(CN)6]4− (Q = Se, Te) led to the formation of the nanomolecular (≈︁2.5 nm) compounds [(CN)2Re6Se8{(CN)Fe(L1)}4]·7H2O (1) and [(CN)2Re6Te8{(CN)Fe(L2)}4]·4CH3CN·4H2O (2). Both compounds were characterized by single‐crystal X‐ray diffraction analysis. Compound 1 crystallizes in the triclinic space group P$\bar 1$
with a = 12.2822(10), b = 14.2524(10), c = 15.8474(10) Å, α = 106.093(10)°, β = 101.992(10)°, γ = 92.438(10)°, and Z = 1. Compound 2 crystallizes in the orthorhombic space group Pbca with a = 19.3024(2), b = 16.8134(3), c = 35.9842(6) Å, and Z = 4. In these two compounds, only four pentadentate compartments are bonded to the Re6 cluster for charge balancing. The magnetic‐susceptibility data show that there is no evidence for interactions between FeIII ions via the central Re6 cluster in either compound. The observed effective magnetic moments suggest that there are low‐spin FeIII ions and high‐spin FeIII ions mixed in each compound. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Recent Advances in the Chemistry of Metallacarboranes
Authors: Hosmane Narayan S. , Maguire John A.
Published: November 2003

Most carborane derivatives of the icosahedral (C2B10) or small cage (C2B4) systems are formed by varying the groups on the cage carbon atoms. This is usually accomplished in the original carborane synthesis by treating substituted acetylenes with either the decaborane(14) or pentaborane(9) precursors to give directly carboranes that have adjacent carbon atoms in the cage (“carbon atoms adjacent”). The larger cages are obtained as closo‐icosahedra, while the small‐cage C2B4 carboranes have nido structures as well as a cage geometry in which the carbon atoms are separated by a boron atom. Although these “carbon atoms apart” or nido‐2,4‐(CR)2B4H6 carboranes are thermodynamically more stable and are more symmetric than the “carbon atoms adjacent” isomers, they have not been as well studied, mainly because they must be synthesized from their “carbon atoms adjacent” analogues through a sequential series of oxidative cage‐closure/reductive cage‐opening reactions. We have concentrated much of our recent research on the reactivity patterns of C(cage)‐appended alkyl‐ and silylamido, alkyloxo, alkylphosphido, and alkylthio derivatives of the “carbon atoms apart” carboranes. We have also sought to develop a safe, bench‐scale preparation of small‐cage carboranes that does not require isolating and handling dangerous and toxic carborane precursors such as pentaborane(9). This microreview discusses the latest developments towards such a process and the subsequent reaction chemistry of the “carbon atoms apart” carboranes. ((© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Dimensionality Variation in Polymeric Metallo‐Organic Frameworks
Authors: Nättinen Kalle I. , Linnanto Juha , Rissanen Kari
Published: November 2003

Single crystal X‐ray crystallography was used to determine the structures of four metallo‐organic complexes derived from pyridyl ligands and the metal ions, Cu2+, Zn2+ and Ag+. Two metallo‐organic layer framework structures (1 and 3), a strand (2) and a dimer (4) structure were formed when the tetradentate ligands, tetrakis(nicotinoxymethyl)methane (TNM) and tetrakis(isonicotinoxymethyl)methane (TINM), were reacted with the first and second row transition metal cations, copper, silver, and zinc. The choice of anion and ligand was found to affect the outcome of the structure. Contrary to our previous results with the same ligands and similar transition metal cations, no genuine 3D metallo‐organic frameworks (MOFs) were obtained. Several factors were found to affect MOF formation: the coordination geometry, the meta‐ or para‐configuration of the coordinating pyridyl moieties and the size and type of the counter anion. In 1, the use of TNM (with a shorter “coordination arm” than TINM), in combination with an octahedral coordination geometry (4 Py, SO42− and H2O) and a relatively large sulfate anion, leads to a sandwich‐like layer structure with the anions between the MOF layers. The layers have a thickness of 2.1 nm. In complex 3, similar layer structures are assembled from four‐ and five‐coordinate (2 Py, NO3−, H2O/2 Py, 3 NO3−) Ag+ ions with TINM and nitrate anions. However, in complex 2, the Zn2+ ion is tetrahedrally (2 Py, 2 Cl−) coordinated, creating an infinite strand structure. Most surprisingly, in complex 4, two arms of the ligand are uncoordinated and a binuclear square‐planar coordination geometry (2 Py, 2 CH3COO−) around the Cu2+ ions, as well as the acetate anions, create a non‐polymeric dimeric structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
C−H Activation by AlCl Monomers: Characterization of HAl(Cl)CH3 as the Product of the Photoactivated Reaction Between AlCl and CH4 in a Solid Ar Matrix at 12 K
Authors: Himmel Hans‐Jörg
Published: November 2003

In a solid Ar matrix at 12 K and upon photoactivation AlCl inserts into the C−H bond of CH4 to give the new monomeric aluminium hydride HAl(Cl)CH3, which was identified and characterized with the aid of the IR spectra recorded for several isotopomers [Cl(H)Al12CH3, Cl(D)Al12CD3, and Cl(H)Al13CH3], comparison with the known IR properties of related molecules and detailed quantum chemical calculations. Calculations yield a Cs symmetric global energy minimum structure for this compound, and that the reaction is slightly exothermic (reaction energy of −43.2 kJ·mol−1). This work demonstrates impressively how reactive photoactivated AlCl molecules are. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Self‐Assembly and Characterisation of Grid‐Type Iron(II), Cobalt(II) and Zinc(II) Complexes
Authors: Patroniak Violetta , Baxter Paul N. W. , Lehn Jean‐Marie , Kubicki Maciej , Nissinen Maija , Rissanen Kari
Published: November 2003

The reaction of the ligands 5 and 6, containing two tridentate binding units, with iron(II), cobalt(II) and zinc(II) leads to the self‐assembly of supramolecular architectures of [2 × 2] grid type containing four ions in octahedral coordination sites. The grid‐type structures have been assigned on the basis of the spectroscopic data in solution, and confirmed in the solid state in the case of complexes 6b and 6c by X‐ray crystallography. The latter study revealed that each metal ion is situated in a distorted octahedral coordination environment comprising two N,N,O ligand donor sets. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Novel Complexes of Ligands Containing Phenol and Alcohol Groups: From Polynuclear Cluster, 1D Coordination Polymer to 2D Supramolecular Assemblies
Authors: Xie Yongshu , Liu Qingliang , Jiang Hui , Ni Jia
Published: November 2003

A series of CoII, CuII, ZnII, AgI and mixed‐valence cobalt complexes 1−9 with tridentate and tetradentate chelating ligands containing oxygen‐bridging and hydrogen‐bonding groups have been synthesized, four of which have been structurally characterized: [Co6L16(OH)(H2O)3]Cl2·10H2O (1) [H2L1 = N‐(2‐hydroxybenzyl)ethanolamine] is a hexanuclear CoIII3CoII3 complex, with a core of quadruple face‐sharing defective cubane‐like units; [CuNaL2(ClO4)]∞ (3) [H2L2 = N,N′‐bis(2‐hyroxybenzyl)ethylenediamine] is a μ3‐phenoxo‐ and μ4‐perchlorato‐bridged 1D heterometallic CuIINaI coordination polymer; the coordination moieties of [CuL3]4·4H2O (6) [H2L3 = N,N′‐bis(2‐hyroxy‐5‐methylbenzyl)ethylenediamine] form a 2D hydrogen‐bonded network structure of monophenoxo‐bridged dimeric moieties; and the molecules of [Ag(H2L2)(HL2)] (9) are connected to give an undulated 2D structure, consisting of hydrogen‐bonded hexagonal units. The variety of these structures is discussed on the basis of the stereoelectronic preferences of the metal atoms, hydrogen bonds, disposition of the bridging groups, steric effect, and conformational flexibility of the ligands. Variable‐temperature magnetic properties of 1 and 6 are also reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
General Synthesis and Characterization of Monocrystalline Lanthanide Orthophosphate Nanowires
Authors: Zhang Ya‐Wen , Yan Zheng‐Guang , You Li‐Ping , Si Rui , Yan Chun‐Hua
Published: November 2003

Monocrystalline LnPO4 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb) nanowires have been prepared in bulk quantities by a simple, facile, and clean solution‐based hydrothermal method at 220−240 °C by finely tuning the acidity of the stock solutions. The length and width of the nanowires were in the range of 1−10 μm and 10−200 nm, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Characterization of the lipid fraction of Niger seeds (Guizotia abyssinica cass.) from different regions of Ethiopia and India and chemometric authentication of their geographical origin
Authors: Marini Federico , Magrì Antonio L. , Marini Domenico , Balestrieri Fabrizio
Published: November 2003

The oil extracted from the seeds of niger (Guizotia Abyssinica), collected from 6 different regions of Ethiopia and India, was characterized in terms of its fatty acid, sterol and triglyceride distribution and of its total tocopherol content. Where available, the results have been compared with those reported in the literature or with data on oils from the same botanical family (Compositae).

The analytical data have then been elaborated by supervised pattern recognition techniques (Linear Discriminant Analysis (LDA) and Artifical Neural Network (ANN)) in order to authenticate the geographical origin of the samples. Eight and 11 variables were necessary to achieve a complete discrimination respectively of the country and of the region of origin of the oils under exam, when using LDA, whereas ANN required a smaller number of experimental variables (4 and 6), due to its non‐linearity.
Lipid deterioration during chilled storage of Atlantic pomfret (Brama brama)
Authors: Pérez‐Alonso Francisco , Arias Cristina , Aubourg Santiago P.
Published: November 2003

Lipid damage produced during Atlantic pomfret (Brama brama) chilled storage (up to 19 d) was studied. The formation of various lipid parameters, such as free fatty acid and conjugated dienes (CD), peroxide value, thiobarbituric acid reactive substances and fluorescent compounds was measured in 2 different white muscle zones (dorsal and ventral). The results were compared with the formation of volatile amines (total volatile base‐nitrogen, TVB‐N, trimethylamine‐nitrogen, TMA‐N). A gradual lipid hydrolysis was observed in both zones during the entire experiment. CD and peroxides formation was prominent during the experiment, whereas peroxides showed the highest value at day 15 in both zones followed by a peroxide breakdown at day 19. Interaction of oxidized lipids with nucleophilic compounds present in the fish muscle led to a gradual development of fluorescent material during storage in both zones. The mean value of the lipid content tended to be higher in the ventral zone than in the dorsal one, although significant differences could not be detected (p >0.05). Concerning the lipid damage, very small differences (p <0.05) could be assessed between both zones. TVB‐N content showed no variation till day 15. At day 19, a sharp increase was observed for both muscle zones. In the case of TMA, a gradual increase was observed in both muscles during the 19‐day storage. Higher mean values of TVB‐N and TMA‐N indices were obtained for the ventral than for the dorsal zone. This might be due to the fact that the ventral zone is close to the viscera, where microorganisms are known to concentrate. Of all the different indices tested for quality assessment, TMA‐N and the formation of fluorescent compounds were strongest related to the duration of storage (r2≥0.87). These might therefore be the most accurate parameters to follow quality loss of chilled Atlantic pomfret.
Extraction of tocopherols from the deodorized distillate of soybean oil with liquefied petroleum gas
Authors: Buczenko Gisele Maria , de Oliveira Juarez Souza , von Meien Oscar Felippe
Published: November 2003

Deodorizer distillate, produced during the last processing step of edible oil refinement, is a mixture of tocopherols, sterols, fatty acids, glycerides, hydrocarbons, water and other materials. The amount of tocopherols in deodorizer distillate is large enough to be considered as raw material for vitamin E preparation. In this work, separation of tocopherols from sterols has been achieved using liquefied petroleum gas (LPG) extraction. LPG was chosen as extraction solvent in order to improve extract recovery and prevent tocopherol degradation.
Selective uptake of fatty acids by the yeast Yarrowia lipolytica
Authors: Papanikolaou Seraphim , Aggelis George
Published: November 2003

Yarrowia lipolytica, when cultivated on mixtures of free fatty acid substrates was found to remove C12:0, C14:0, Δ9C18:1, Δ9, 12C18:2 and Δ9, 12, 15C18:3 at significantly higher rates than C16:0 and C18:0, regardless of fatty acid composition of the initial substrate. C12:0, C14:0 and Δ9, 12, 15C18:3 were specifically and completely removed from the substrate, while Δ9C18:1 and Δ9, 12C18:2 concentrations decreased by 55‐80 wt‐% in comparison with initial concentrations. In contrast, concentration of C18:0 increased 2.1—3.5 fold in the substrate. Although C18:0 was removed slowly from the substrate, this fatty acid was selectively accumulated in the storage lipid. Inversely, only low quantities of Δ9C18:1 and Δ9, 12C18:2 and traces of C12:0, C14:0 and Δ9, 12, 15C18:3 were accumulated in the storage lipid. During storage lipid breakdown, cellular C16:0 and Δ9C18:1 were taken up more rapidly than C18:0. We concluded that the capability of Yarrowia lipolytica to selectively remove several fatty acids from the substrate and accumulate others could be used in modification of the composition of selected mixtures of fatty acids and probably of common fats, to produce “new” fats with a predetermined composition.
Rapid simultaneous determination by proton NMR of unsaturation and composition of acyl groups in vegetable oils
Authors: Guillén María D. , Ruiz Ainhoa
Published: November 2003

1H NMR spectra of 66 samples of edible oils from 14 different botanical origins were acquired. Assignment of signal spectra to the different types of hydrogen atoms was made and the areas of the signals determined. Considering that the area of the signals of the spectra is proportional to the number of hydrogen atoms of each type in the sample, it is possible to calculate not only the iodine value, but also the proportion of different acyl groups from the data. Determination of both parameters requires only a few minutes and one spectroscopic run. Classical methodology however, requires two separate wet methods for determining the unsaturation degree (iodine value) and the proportions of different acyl groups; both of them involve chemical transformations of the sample and considerable time and cost. Determination of acyl group proportions in samples by 1H NMR, which was validated with mixtures of standard triglycerides, provides accurate results and is able to detect small differences between samples of very similar composition.
Lipase‐catalyzed alcoholysis of vegetable oils
Authors: Soumanou Mohamed M. , Bornscheuer Uwe T.
Published: November 2003

Fatty acid alkyl esters were produced from various vegetable oils by transesterification with different alcohols using immobilized lipases. Using n‐hexane as organic solvent, all immobilized lipases tested were found to be active during methanolysis. Highest conversion (97%) was observed with Thermomyces lanuginosa lipase after 24 h. In contrast, this lipase was almost inactive in a solvent‐free reaction medium using methanol or 2‐propanol as alcohol substrates. This could be overcome by a three‐step addition of methanol, which works efficiently for a range of vegetable oils (e.g. cottonseed, peanut, sunflower, palm olein, coconut and palm kernel) using immobilized lipases from Pseudomonas fluorescens (AK lipase) and Rhizomucor miehei (RM lipase). Repeated batch reactions showed that Rhizomucor miehei lipase was very stable over 120 h. AK and RM lipases also showed acceptable conversion levels for cottonseed oil with ethanol, 1‐propanol, 1‐butanol and isobutanol (50‐65% conversion after 24 h) in solvent‐free conditions. Methyl and isopropyl fatty acid esters obtained by enzymatic alcoholysis of natural vegetable oils can find application in biodiesel fuels and cosmetics industry, respectively.
Solvent‐Free Microwave‐Assisted Efficient Synthesis of 4,4‐Disubstituted 2‐Oxazolines
Authors: García‐Tellado Fernando , Loupy André , Petit Alain , Marrero‐Terrero Alma Leilani
Published: November 2003

4,4‐Disubstituted 2‐oxazolines have been synthesized by a microwave‐promoted solvent‐free direct condensation of carboxylic acids and disubstituted β‐amino alcohols in good to excellent yields. Zinc oxide is a very good solid support in cases where a Lewis acid is required. The method described herein is a very good, safe, clean, economical, and environmentally friendly alternative to the classical procedures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)