bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and characterization of N‐substituted hyperbranched polyureas
Authors: Ambade Ashootosh V. , Kumar Anil
Published: September 2004

N,N′‐disubstituted hyperbranched polyureas with methyl, benzyl, and allyl substitutents were synthesized starting from AB2 monomers based on 3,5‐diamino benzoic acid. Carbonyl azide approach, which generates isocyanate group in situ on thermal decomposition, was used for the protection of isocyanate functional groups. The N‐substituted hyperbranched polymers can be considered as the new class of internally functionalized hyperbranched polyureas wherein the substituent can function either as receptor or as a chemical entity for selective transformations as a tool to tailor the properties. The chain‐ends were also modified by attaching long chain aliphatic groups to fully realize the interior functionalization. This approach opens up a possible synthetic route wherein different functional substituents can be used to generate a library of internally functionalized hyperbranched polymers. All the hyperbranched polyureas were characterized by FTIR, 1H‐NMR, DSC, TGA, and size exclusion chromatography. Degree of branching in these N,N′‐disubstituted hyperbranched polyureas, as calculated by 1H‐NMR spectroscopy using model compounds, was found to be lower than the unsubstituted hyperbranched polyurea and is attributed to the lower reactivity of N‐substituted amines compared to that of unsubstituted amines. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5134–5145, 2004
Free‐radical polymerization of dioxolane and dioxane derivatives: Effect of fluorine substituents on the ring opening polymerization
Authors: Liu Weihong , Mikeš František , Guo Yinzhong , Koike Yasuhiro , Okamoto Yoshi
Published: September 2004

Partially fluorinated and perfluorinated dioxolane and dioxane derivatives have been prepared to investigate the effect of fluorine substituents on their free‐radical polymerization products. The partially fluorinated monomer 2‐difluoromethylene‐1,3‐dioxolane (I) was readily polymerized with free‐radical initiators azobisisobutyronitrile or tri(n‐butyl)borane–air and yielded a vinyl addition product. However, the hydrocarbon analogue, 2‐methylene‐1,3‐dioxolane (II), produced as much as 50% ring opening product at 60 °C by free‐radical polymerization. 2‐Difluoromethylene‐4‐methyl‐1,3‐dioxolane (III) was synthesized and its free‐radical polymerization yielded ring opening products: 28% at 60 °C, decreasing to 7 and 4% at 0 °C and −78 °C, respectively. All the fluorine‐substituted, perfluoro‐2‐methylene‐4‐methyl‐1,3‐dioxolane (IV) produced only a vinyl addition product with perfluorobenzoylperoxide as an initiator. The six‐membered ring monomer, 2‐methylene‐1,3‐dioxane (V), caused more than 50% ring opening during free‐radical polymerization. However, the partially fluorinated analogue, 2‐difluoromethylene‐1,3‐dioxane (VI), produced only 22% ring opening product with free‐radical polymerization and the perfluorinated compound, perfluoro‐2‐methylene‐1,3‐dioxane (VII), yielded only the vinyl addition polymer. The ring opening reaction and the vinyl addition steps during the free‐radical polymerization of these monomers are competitive reactions. We discuss the reaction mechanism of the ring opening and vinyl addition polymerizations of these partially fluorinated and perfluorinated dioxolane and dioxane derivatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5180–5188, 2004
Synthesis of functional polymers—Vinylidene fluoride based fluorinated copolymers and terpolymers bearing bromoaromatic side‐group
Authors: Souzy R. , Ameduri B. , Boutevin B.
Published: September 2004

The radical co‐ and terpolymerization of 4‐[(α,β,β‐trifluorovinyl)oxy]bromo benzene (TFVOBB) with 1,1‐difluoroethylene (or vinylidene fluoride, VDF, or VF2), hexafluoropropene (HFP), perfluoromethyl vinyl ether (PMVE), and chlorotrifluroroethylene (CTFE) is presented. Although TFVOBB could be thermocyclodimerized, it could not homopolymerize under radical initiation. TFVOBB could be copolymerized in solution under a radical initiator with VDF or CTFE comonomers, while its copolymerization with HFP or PMVE were unsuccessful. The terpolymerization of TFVOBB with VDF and HFP, or VDF and PMVE, or VDF and CTFE also led to original fluorinated terpolymers bearing bromoaromatic side‐groups. The conditions of co‐ and terpolymerization were optimized in terms of the nature of the radical initiators, and of the nature of solvents (fluorinated or nonhalogenated). Various monomer concentrations in the co‐ and terpolymers were assessed by19F and1H‐NMR spectroscopy. The thermal and physico chemical properties were also studied. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5077–5097, 2004
Novel thermotropic liquid crystalline‐cum‐photocrosslinkable polyvanillylidene alkyl/arylphosphate esters
Authors: Sakthivel P. , Kannan P.
Published: September 2004

A new class of linear unsaturated polyphosphate esters based on divanillylidene cyclohexanone possessing liquid crystalline‐cum‐photocrosslinkable properties have been synthesized from 2,6‐bis[n‐hydroxyalkyloxy(vanillylidene)]cyclohexanone [n = 6,8,10] with various alkyl/aryl phosphorodichloridates in chloroform at ambient temperature. The resultant polymers were characterized by intrinsic viscosity, FT‐IR, 1H, 13C, and 31P‐NMR spectroscopy. All the polymers showed anisotropic behavior under hot stage optical polarized microscope (HOPM). The liquid crystalline textures of the polymers became more transparent with increasing spacer length. The thermal behavior of the polymers was studied by thermogravimetric analysis and differential scanning calorimetry. The Tg, Tm, and Ti of the polymers decreased with increasing flexible methylene chain. The photocrosslinking property of the polymer was investigated by UV light/UV spectroscopy; the crosslinking proceeds via 2π‐2π cycloaddition reactions of the divanillylidene exocyclic double bond of the polymer backbone. The pendant alkyloxy containing polymers show faster crosslinking than the pendant phenyloxy containing polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5215–5226, 2004
Cure kinetics of carbon nanotube/tetrafunctional epoxy nanocomposites by isothermal differential scanning calorimetry
Authors: Xie Hongfeng , Liu Binghua , Yuan Zuanru , Shen Jianyi , Cheng Rongshi
Published: September 2004

The cure kinetics of tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM) and 4,4′‐diaminodiphenylsulfone (DDS) as a cure agent in nanocomposites with multiwalled carbon nanotubes (MWNTs) have been studied with an isothermal differential scanning calorimetry (DSC) technique. The experimental data for both the neat TGDDM/DDS system and for epoxy/MWNTs nanocomposites showed an autocatalytic behavior. Kinetic analysis was performed with the phenomenological model of Kamal and a diffusion control function was introduced to describe the cure reaction in the later stage. Activation energies and kinetic parameters were determined by fitting experimental data. For MWNTs/epoxy nanocomposites, the initial reaction rates increased and the time to the maximum rate decreased with increasing MWNTs contents because of the acceleration effect of MWNTs. The values of the activation energies for the epoxy/MWNTs nanocomposites were lower than the values for the neat epoxy in the initial stage of the reaction. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3701–3712, 2004
Blends of a thermotropic liquid‐crystalline polymer and a poly(butylene terephthalate)/organoclay nanocomposite
Authors: Chang Jin‐Hae , Seo Bo‐Soo , Kim Seong Hun
Published: September 2004

Blends were synthesized via the melt blending of a thermotropic liquid‐crystalline polymer (TLCP) and a poly(butylene terephthalate) (PBT) hybrid containing 2 wt % organoclay. A TLCP was also synthesized with side groups based on a nematic liquid‐crystalline phase. The blends of TLCPs with PBT hybrids were melt‐spun with different concentrations of the liquid‐crystalline polymer and different draw ratios (DRs) to produce monofilaments. Regardless of the TLCP concentration in the hybrids, transmission electron microscopy photographs proved that the clay layers of the organoclay were intercalated and partially exfoliated in the PBT matrix. At DR = 1, the maximum enhancement in the ultimate tensile strength was observed for blends containing 8% TLCP, and the tensile strength decreased with further increases in the TLCP concentration. The initial modulus monotonically increased with increasing TLCP concentration. When DR increased from 1 to 44, the increased stretching caused the tensile property to decrease significantly, debonding to occur, and voids to form. These trends with increasing DR were observed in all the systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3667–3676, 2004
Tunable nanopatterning by diblock copolymers in small confinements*
Authors: Rasmussen K. Ø.
Published: September 2004

Here we study the effects of confinement on the self‐assembly of diblock copolymers. Specifically, we study the hexagonal cylindrical phase as it self‐assembles within a narrow confinement. We quantify the structural deformation of the cylindrical morphology that arises from the frustration that the narrow confinements exert on the system when the confinement width is incompatible with the lattice structure of the bulk mesophase. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3695–3700, 2004
Surface Analysis of Plasma‐Deposited Polymer Films, 1
Authors: Oran Umut , Swaraj Sufal , Friedrich Jörg F. , Unger Wolfgang E. S.
Published: September 2004

Summary: Pulsed plasma‐deposited polystyrene films were studied by time‐of‐flight static secondary ion mass spectrometry (ToF‐SSIMS) before and after exposure to ambient air. The influence of the external plasma parameters on the secondary ion mass spectra of plasma‐deposited polystyrene films was investigated. From these data, information on the chemical character of the plasma polystyrene films was derived. In the range of deposition conditions applied in this study, the fragmentation of styrene is a minor process. The main process is probably the radical chain propagation to polymers. All the polystyrene plasma polymers, relying on ToF‐SIMS, seem to be rather similar to a reference polystyrene oligomer sample. When the plasma polymers are exposed to air, extensive oxygen incorporation occurs. Oxygen uptake was found to alter the emission probabilities of secondary ions. A relation between the regularity of the plasma polymers and the amount of oxygen incorporation was found. The result was that the chemical regularity of the plasma polystyrene decreases when the effective power in the plasma is increased.

ToF‐SSIMS spectra of PP‐PS‐1 before exposure (left) and after two weeks exposure (right) to air. The intensity of the oxygen containing fragments increase indicating an increase on the amount of oxygen incorporation.

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ToF‐SSIMS spectra of PP‐PS‐1 before exposure (left) and after two weeks exposure (right) to air. The intensity of the oxygen containing fragments increase indicating an increase on the amount of oxygen incorporation.
Oxidative Degradation of Nitrophenols in Aqueous Solution Induced by Plasma with Submersed Glow Discharge Electrolysis
Authors: Gao Jinzhang , Pu Lumei , Yang Wu , Yu Jie , Li Yan
Published: September 2004

Summary: The oxidative degradation of 4‐nitrophenol, 2,4‐dinitrophenol, and 2,4,6‐trinitrophenol in aqueous solution induced by plasma with submersed glow discharge has been investigated. The reaction intermediates were determined by high performance chromatography (HPLC). Various influencing factors such as the initial pH, the concentration of nitrophenols (NPs), and the catalytic action of Fe2+ were examined. The results indicate that the degradation pathways involve a slow opening of the aromatic ring followed by a rapid oxidation of the aliphatic compounds. The hydroxyl radicals are responsible for the primary attack of the NPs with formation of dihydroxynitrobenzenes. The attack of hydroxyl radical occurs at the ring positions activated by the presence of a phenolic OH group and a nitro group. The results suggested that the reaction obeyed a pseudo‐first order kinetic reaction and the proposed method is an efficient way for the nitrophenols degradation.

Effect of pH on the degradation of 4‐nitrophenol.

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Effect of pH on the degradation of 4‐nitrophenol.
Continuous and Modulated Deposition of Fluorocarbon Films from c‐C4F8 Plasmas
Authors: Milella Antonella , Palumbo Fabio , Favia Pietro , Cicala Grazia , d'Agostino Riccardo
Published: September 2004

Summary: Continuous and modulated c‐C4F8 (perfluorocyclobutane) plasmas were used to deposit thin Teflon‐like films. Gas phase and film composition and structure were investigated and the results can be rationalized with the deposition mechanism developed in a previous work for C2F4‐modulated plasmas. The effect of modulation on the morphology and the chemistry of the surface were studied.

CFx percentages as a function of the duty cycle for films deposited for 90 min from modulated discharges sustained at 100 W, 300 mtorr, and 6 sccm.

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CFx percentages as a function of the duty cycle for films deposited for 90 min from modulated discharges sustained at 100 W, 300 mtorr, and 6 sccm.
Rock‐wall temperatures in the Alps: modelling their topographic distribution and regional differences
Authors: Gruber Stephan , Hoelzle Martin , Haeberli Wilfried
Published: September 2004

Rising temperatures or the complete thaw of permafrost in rock walls can affect their stability. Present as well as projected future atmospheric warming results in permafrost degradation and, as a consequence, makes knowledge of the spatial distribution and the temporal evolution of rock temperatures important. Rock‐face near‐surface temperatures have been measured over one year at 14 locations between 2500 and 4500 m a.s.l. in the Alps. Different slope aspects have been included in order to capture the maximum spatial differentiation of rock temperatures. These data were used to further develop and verify an energy‐balance model that simulates daily surface temperatures over complex topography. Based on a 21‐year (1982–2002) run of this model, spatial patterns of rock‐face temperatures in the Swiss Alps are presented and discussed. This model provides a basis for the re‐analysis of past rock‐fall events with respect to permafrost degradation as well as for the simulation of future trends of rock temperatures. Furthermore, the spatial patterns of rock‐wall temperatures provide a quantitative insight into the topography‐related mechanisms affecting permafrost distribution in Alpine areas without local influence from snow cover or an active layer with a complex thermal offset. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of deep inspiration on airway caliber in children with asthma
Authors: Assefa Dagnachew , Amin Nikhil , Dozor Allen J.
Published: September 2004

The objective of this study was to assess the effect of deep inspiration (DI) on airway caliber in school‐age children with asthma. Thirty children with asthma (10 from each group of mild, moderate, and severe persistent asthma as defined by the National Asthma Education and Prevention Program guidelines of the National Heart, Lung, and Blood Institute) were enrolled, and their results were compared to those obtained in 7 healthy children. Subjects performed a partial expiratory flow volume curve (P) initiated from ∼70% of vital capacity (VC) followed by a maximal expiratory flow volume (M) maneuver begun from total lung capacity (TLC). The M/P ratio at 30% of the VC (M/P30) was calculated. Specific airway conductance (sGaw) was measured before and immediately after DI, using standard techniques. Differences in M/P30 and sGaw ratios between asthma and control groups were compared with Student's unpaired t‐tests. One‐way ANOVA was used to compare the effect of DI on M/P30 and sGaw ratios among the various asthma severity groups. The M/P30 ratio (mean ± 1 SD) was significantly lower in children with moderate and severe persistent asthma (0.73 ± 0.21 and 0.72 ± 0.1, respectively) than in healthy controls (1.69 ± 0.62) (P < 0.05). In mild persistent asthmatics, there was limited bronchodilation (M/P30 = 1.1 ± 0.35, P = 0.052). There was a significant inverse correlation between M/P30 ratio and severity of asthma (r = −0.684, P < 0.01). The mean sGaw ratio was decreased in asthmatic subjects compared to healthy controls (0.98 ± 0.17 vs. 1.13 ± 0.16, P = 0.062). In conclusion, in school‐age children, the effects of DI on airway caliber are similar in direction to those observed in adults, i.e., bronchodilation in healthy and mild asthmatics, and bronchoconstriction (BC) in moderate to severe asthmatics. This finding suggests that forces that determine airway caliber in school‐age children are similar to those forces in adults. © 2004 Wiley‐Liss, Inc.
Influence of organic carbon on reductive dechlorination of thiobencarb in California rice field soils
Authors: Schmelzer Kara R , Johnson Catherine S , Viant Mark R , Williams John F , Tjeerdema Ronald S
Published: September 2004

The herbicide thiobencarb is suspected of causing delayed phytotoxicity syndrome (DPS) in rice plants. While the ultimate agent appears to be its dechlorinated product (deschlorothiobencarb), the influence of organic carbon on the formation of deschlorothiobencarb in California rice field soils has not been investigated. Thus, two different soils were compared for their ability to reductively dechlorinate thiobencarb with carbon augmentation: one from the eastern Sacramento Valley, which has historically displayed DPS, and one from the western Sacramento Valley, which has not. Rice straw was homogenized into samples of each soil to produce 0, 0.33 or 2% organic carbon augmentation. During 90‐days of anoxic incubation, substantial deschlorothiobencarb production was measured in both soil types. However, only the thiobencarb degradation rate in the eastern valley soil was positively correlated with carbon content. Thus, other characteristics of DPS‐resistant soils may limit deschlorothiobencarb formation. Copyright © 2004 Society of Chemical Industry
White light emitting silicon nanocrystals as nanophosphor
Authors: Lee Soojin , Cho Woon Jo , Han Il Ki , Choi Won Jun , Lee Jung Il
Published: September 2004

We exploited the practical sonochemical route for preparing silicon nanocrystals at room temperature and ambient pressure. This synthesis provided the very fast reaction within a few hours and the useful modification for the surface of silicon nanoparticles. The average size of prepared nanocrystals was 2.8 nm and confirmed by TEM images. The chlorine‐capped nanoparticles were characterized by FT‐IR spectroscopy. The luminescence of silicon colloid was observed in the wide range between 340 nm and near 700 nm and showed white color with commercial low‐intensity UV‐lamp exposure. This synthetic strategy is potentially applicable for illuminating devices such as white light emitting diodes. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Properties of the fundamental absorption edge of InN crystals investigated by optical reflection and transmission spectra
Authors: Ishitani Y. , Xu K. , Che S. B. , Masuyama H. , Terashima W. , Yoshitani M. , Hashimoto N. , Akasaka K. , Ohkubo T. , Yoshikawa A.
Published: September 2004

InN crystals are grown on sapphire substrates using a plasma‐assisted MBE system. The carrier concentrations of the samples are 2 × 1018–1 × 1019 cm–3. Optical transmission and reflectance measurements are performed on these samples in the temperature range 5–300 K. The resultant spectra are analysed by theoretical spectra based on the LO‐phonon–plasmon coupling scheme for the phonon‐related factor and non‐parabolic conduction band structure for the electronic transition factor. The observed absorption edge is estimated to originate from a valence band to conduction band transition rather than a defect‐ or impurity‐related transition. It is estimated that InN has a bandgap energy in the range 0.59–0.65 eV. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Joint ―X and R Charts with Two‐stage Samplings
Authors: Costa Antonio F. B. , Rahim M. A.
Published: September 2004

When joint ―X and R charts are in use, samples of fixed size are regularly taken from the process, and their means and ranges are plotted on the ―X and R charts, respectively. In this article, joint ―X and R charts have been used for monitoring continuous production processes. The sampling is performed, in two stages. During the first stage, one item of the sample is inspected and, depending on the result, the sampling is interrupted if the process is found to be in control; otherwise, it goes on to the second stage, where the remaining sample items are inspected. The two‐stage sampling procedure speeds up the detection of process disturbances. The proposed joint ―X and R charts are easier to administer and are more efficient than the joint ―X and R charts with variable sample size where the quality characteristic of interest can be evaluated either by attribute or variable. Copyright © 2004 John Wiley & Sons, Ltd.
Nonlinear generalization of scaled ℋ︁∞control: global robustification against nonlinearly bounded uncertainties
Authors: Ito Hiroshi
Published: September 2004

This paper proposes a novel approach to the problem of ℒ︁2disturbance attenuation with global stability for nonlinear uncertain systems by placing great emphasis on seamless integration of linear and nonlinear controllers. This paper develops a new concept of state‐dependent scaling adapted todynamicuncertainties andnonlinear‐gain boundeduncertainties that do not necessarily have finite linear‐gain, which is a key advance from previous scaling techniques. The proposed formulation of designing global nonlinear controllers is not only a natural extension of linear robust control, but also the approach renders the nonlinear controller identical with the linear control at the equilibrium. This paper particularly focuses on scaled ℋ︁∞control which is widely accepted as a powerful methodology in linear robust control, and extends it nonlinearly. If the nonlinear system belongs to a generalized class of triangular systems allowing for unmodelled dynamics, the effect of the disturbance can be attenuated to an arbitrarily small level with global asymptotic stability by partial‐state feedback control. A procedure of designing such controllers is described in the form of recursive selection of state‐dependent scaling factors. Copyright © 2004 John Wiley & Sons, Ltd.
Multi‐objective learning control for robotic manipulator
Authors: Win Khin Kyu Kyu , Cheah Chien‐Chern
Published: September 2004

Several types of learning controllers have been proposed in the literature to improve the tracking performance of robot manipulators. In most cases, the learning algorithms emphasize mainly on a single objective of learning a desired motion of the end‐effector. In some applications, more than one objective may be specified at the same time. For example, a robot may be required to follow a desired trajectory (primary objective) and at the same time avoid an obstacle (secondary objective). Thus, multi‐objective learning control can be more effective to realize the collision‐free tasks. In this paper, a multi‐objective learning control problem is formulated and solved. In the proposed learning control system, the primary objective is to track a desired end‐effector's motion and several secondary objectives can be specified for the desired orientation and for obstacles avoidance. To avoid obstacles in the workspace, a new learning concept called “region learning control” is also proposed in this paper. The proposed learning controllers do not require the exact knowledge of robot kinematics and dynamics. Sufficient condition is presented to guarantee the convergence of the learning system. The proposed learning controllers are applied to a four‐link planar redundant manipulator and simulation results are presented to illustrate the performance. © 2004 Wiley Periodicals, Inc.
Self‐assembly of stearic acid on aluminium: the importance of oxide surface chemistry
Authors: Pertays K. M. , Thompson G. E. , Alexander M. R.
Published: September 2004

The influence of ambient atmospheric exposure on the chemistry of the magnetron‐sputtered aluminium surface has been characterized as hydroxyl incorporation to the oxide surface and concurrent adsorption of airborne carbonaceous contamination. Here, the consequence of these changes in oxide surface chemistry upon the adsorption of stearic acid from solution is investigated. Water contact angle and polarization modulation infrared refection–absorption spectroscopy (PM‐IRRAS) reveal a strong dependence of stearic acid monolayer order upon ambient exposure time prior to assembly. It is proposed that hydroxyl formation in the ambient atmosphere increases the stearic acid adsorption density and thus the self‐assembled monolayer (SAM) order, whereas airborne carbonaceous material blocks these adsorption sites and introduces disorder in the monolayers through a decrease in adsorption density.

Monolayer adsorption has been correlated with the aluminium oxide surface chemistry. It is proposed that this phenomenon represents an explanation for the irreproducible results often reported for assembly on metal oxide substrates. Furthermore, it indicates that in this broad class of material surfaces assembly can be used as a means of estimating the reactivity of surfaces with respect to organic overlayers such as paints and adhesives. Removal of adsorbed carbonaceous material from the aluminium surface using an oxygen plasma resulted in a significantly increased order of the stearic acid monolayer, as assessed by water contact angle. This observation is rationalized as the removal of carbonaceous material blocking surface adsorption sites by the plasma, but retention of the underlying hydroxyl functionality. This is predicted to have important implications in the preparation of aluminium for painting and adhesive bonding. Copyright © 2004 John Wiley & Sons, Ltd.
Arrested emotional development: Connecting college men, emotions, and misconduct
Authors: Ludeman Randall B.
Published: September 2004

This chapter presents a critical postmodern challenge to higher education professionals dealing with college men, their emotional development, and behavioral issues.
Neue Messe Mailand – Netzstruktur und Tragverhalten einer Freiformfläche
Authors: Schober Hans , Kürschner Kai , Jungjohann Hauke
Published: September 2004

Die Verbindungswege zwischen den einzelnen Bereichen der neuen Messe Mailand werden größtenteils durch architektonisch sehr reizvolle Stahl‐Glas‐Konstruktionen überdeckt. Am Haupteingang entsteht das ‘Logo’: eine zweiachsig gekrümmte Freiformfläche, die mit ca. 37 m wie ein Vulkan in die Höhe ragt und somit bereits von der Ferne als Wahrzeichen zu erkennen sein wird. Ein 1300 m langes und 30 m breites freigeformtes Glasdach, das sog. ‘Vela’, erschließt in der Hauptachse der Messe die einzelnen Hallen und nimmt sich die in Sichtweite befindlichen Alpen in seiner Formgebung wieder auf. Insbesondere am Beispiel des ‘Logo’ beschreibt der Beitrag neben der allgemeinen Entwurfsidee schwerpunktmäßig die Prinzipien zur Ermittlung der Netzgeometrie und die Besonderheiten der Tragstruktur der beliebig gekrümmten Freiformflächen.
Ermittlung der Grenztragfähigkeit von Mehrschraubenverbindungen bei Normalkraft‐Biegemoment‐Interaktion
Authors: Stephan Sören , Stutzki Christian
Published: September 2004

Dieser Aufsatz beschreibt eine zur Anwendung in Computerprogrammen geeignete, allgemeine Methode zur Bemessung von Ein‐ und Mehrschraubenverbindungen von Stäben mit beliebigen dünnwandigen Querschnitten. Diese Methode basiert auf dem klassischen Verfahren der Dehnungsiteration zur Ermittlung der Spannungsverteilung in Querschnitten. Die Grenztragfähigkeit der Schraubenverbindung wird hierbei auf der Grundlage einer iterativen numerischen Bestimmung der elastisch‐plastischen Spannungsverteilung in den Anschlußelementen ermittelt. Die Berechnungsmethode wird in zwei Schritten entwickelt – zuerst wird die numerische Bestimmung der Spannungsverteilung für eine gegebene Schnittgrößenkombinationen gezeigt und danach wird die Bestimmung der Grenztragfähigkeit der Schraubenverbindung dargestellt. Weiterhin wird ein analytisches Verfahren zur Bemessung von Mehrschrauben‐Rundrohrverbindungen hergeleitet. Schließlich werden die Ergebnisse der numerischen und analytischen Berechnungen mit entsprechenden Versuchsergebnissen verglichen.
Einbauteile unter Querkraft‐ und Biegemomentenbeanspruchung
Authors: Ritscher Dieter , Osterland Kay
Published: September 2004

Der Beitrag beschreibt im ersten Teil die theoretischen Grundlagen der Lasteinleitung von in Beton eingespannten Stahlstäben zur Aufnahme von Querkräften und Biegemomenten bei Einhaltung der zulässige Pressung im Beton. Ziel der Überlegung ist der Verzicht auf Schubpratzen, die z. B. bei einer Untermörtelung der Fußplatte schwer oder gar nicht realisierbar sind. Im zweiten Teil wird die Einleitung der Querkraft aus Einbauplatten über angeschweißte Schubbolzen anstelle der üblichen Schubpratzen behandelt. Einbauplatten mit kleinformatigen Schubbolzen sind leicht in die Bewehrung einbaubar und benötigen meist keine speziellen Aussparungen.
Starch Modification, Destructuration and Hydrolysis during O‐Formylation
Authors: Divers Thomas , Pillin Isabelle , Feller Jean‐François , Levesque Guy , Grohens Yves
Published: September 2004

The mixing of dry starch with 40 or 99% (v/v) formic acid (FA) produces an O‐formylation reaction which causes a combination of acid hydrolysis and starch destructuration. Moreover, this esterification reaction is highly exothermic in the presence of pure FA. When O‐formylation is performed at temperatures higher than 20°C, starch formate content is high (degree of substitution, DS, of 2.15 after 60 min at 105°C) but then molecular weight decreases (ηred ≶ 10 mL/g). Under thermally‐controlled conditions at 20°C in formic acid, degrees of substitution reach 1.5–1.6 after 6 h reaction times and polymer degradation seems to be limited (ηred = 110 to 140 mL/g). The degrees of substitution obtained in water/formic acid mixtures are below those in formic acid alone. The level of destructuration of starch in formic acid and water/formic acid mixtures was also evidenced by dynamic rheological measurements and optical microscopy. Plots of storage modulus (G’) versus frequency (ω) was used to characterize both the gelatinization and the gel destruction processes as a function of reaction temperature (Tr) and FA concentration.
Impact of Annealing on the Physicochemical Properties of Unfermented Cassava Starch (“Polvilho Doce”)
Authors: Gomes Anida M. M. , da Silva Claudio E. Mendes , Ricardo Nágila M. P. S. , Sasaki José M. , Germani Rogério
Published: September 2004

Unfermented cassava starch (“polvilho doce”) was subject to annealing treatment at 50°C for 24, 48, 96, 120, 168 and 192 h, in 1:5 starch to water ratio. The annealing treatment changed the internal structure of “polvilho doce” at increasing treatment time. Peak viscosities decreased significantly, denoting that there was a decrease in leaching of amylose from the granules. The pasting temperatures were increased, setback and breakdown were reduced while hold and final viscosities increased, showing an improvement of the stability of the paste. Swelling power and solubility were reduced at all temperatures and the solubility at 55°C was zero after 120 h of treatment. The DSC data for To, Tp, Tc and ΔH increased and the gelatinization range was narrowed. The X‐ray diffractograms changed from CA to A pattern (samples annealed for 48, 96, 120, 168 and 192 h), denoting an increase in organization of double helices of amylopectin. Annealing imparts to the samples some waxy starches characteristics which can be very useful in the food industry.
Effect of Octenylsuccinylation on Rheological Properties of Corn Starch Pastes
Authors: Park Sunae , Chung Man‐Gon , Yoo Byoungseung
Published: September 2004

Rheological properties of corn starch octenylsuccinate (OSA starch) pastes (5%, w/w), at different 1‐octenylsuccinic anhydride (OSA) contents (0, 1.0, 1.5, 2.0 and 2.5%, w/w) were evaluated in steady and dynamic shear. The OSA starch pastes had high shear‐thinning behaviors and their flow behaviors were described by power law, Casson, and Herschel‐Bulkley models. Magnitudes of consistency index (K, Kh) and yield stress (σoc, σh) increased with the increase in OSA content and the decrease in temperature. Over the temperature range of 10–50°C, the effect of temperature on apparent viscosity (ηa,100) was described by the Arrhenius equation. The activation energy values (Ea = 10.7–13.9 kJ/mol) of OSA starches were lower than that (Ea = 15.9 kJ/mol) of native starch. Dynamic frequency sweep test showed that both storage modulus (G′) and loss modulus (G′′) of OSA starch pastes increased with the increase in OSA content. Dynamic (η*) and steady shear (ηa) viscosities of OSA starch pastes at various OSA contents did not follow the Cox‐Merz superposition rule.
Gary C. Hart
Authors: Hart Gary C.
Published: September 2004

This paper presents a summary of the career of the author. It spans his days at the University of Southern California and Stanford University, his 33 years as a Professor of Structural Engineering at the University of California at Los Angeles, and his career as a consulting structural engineer. Copyright © 2004 John Wiley & Sons, Ltd.
Nabih Youssef
Authors: Youssef Nabih
Published: September 2004

This paper presents the work of Nabih Youssef as a contribution to the larger scientific and engineering community through a conceptually holistic approach to engineering methods. Nabih Youssef received his BS in Structural Engineering from Cairo University in 1967. In 1971, he received his MS from California State University in Los Angeles and in 1974 completed a postgraduate Diploma in Earthquake Engineering at UCLA. In addition to a prolific professional career, Nabih has taught at universities for over 20 years and is constantly entrenched in public and professional service duties. His positions as Past Chair of the Vision 2000 Committee and the Seismology Committee for the Structural Engineers Association of California (SEAOC) heavily contributed to the enactment of performance‐based design, a major conceptual breakthrough for the engineering community and in great use today. Nabih Youssef & Associates was formed in 1989, and has been the recipient of numerous awards and publicity for their innovative structural systems. Copyright © 2004 John Wiley & Sons, Ltd.
Evaluating acute toxicity of methyl parathion application in constructed wetland mesocosms
Authors: Milam C. D. , Bouldin J. L. , Farris J. L , Schulz R. , Moore M. T. , Bennett E. R. , Cooper C. M. , Smith S.
Published: September 2004

Wetland ecosystems have reduced ambient levels of various organic and metallic compounds, although their effectiveness on agricultural pesticides is not well documented. Five stations within each of two 10 × 50 m constructed wetlands (two vegetated, two nonvegetated) were selected to measure the fate and effects of methyl parathion (MeP). Following a simulated storm event (0.64 cm of rainfall), aqueous, sediment, and plant samples were collected and analyzed spatially (5, 10, 20, and 40 m from the inlet) and temporally (after 3–10 days) for MeP concentrations and for the impact of those concentrations on the aquatic fauna. Aqueous toxicity to fish decreased spatially and temporally in the vegetated mesocosm. Pimephales promelas survival was significantly reduced, to 68%, at the 10‐m station of the nonvegetated wetlands (3 h postapplication), with pesticide concentrations averaging 9.6 μg MeP/L. Ceriodaphnia in both the vegetated and nonvegetated wetlands was sensitive (i.e., a significant acute response to MeP occurred) to pesticide concentrations through 10 days postapplication. Mean MeP concentrations in water ranged from 0.5 to 15.4 μg/L and from 0.1 to 27.0 μg/L in the vegetated and nonvegetated wetlands, respectively. Hyalella azteca aqueous tests resulted in significant mortality in the 5‐m vegetated segment 10 days after exposure to MeP (2.2 μg/L). Solid‐phase (10‐day) sediment toxicity tests showed no significant reduction in Chironomus tentans survival or growth, except for the sediments sampled 3 h postapplication in the nonvegetated wetland (65% survival). Thereafter, midge survival averaged >87% in sediments sampled from both wetlands. These data suggest that wetlands play a significant role in mitigating the effect of MeP exposure in sensitive aquatic biota. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 471–479, 2004.
First report of cyanobacteriumCylindrospermopsis raciborskiifrom Algerian freshwaters
Authors: Bouaïcha Noureddine , Nasri Aïcha‐Beya
Published: September 2004

This study investigated the first report of the cyanobacteriumCylindrospermopsis raciborskiiin Algerian freshwaters. The morphological characteristics of the two morphotypes observed in Lake Oubeira (Algeria) conformed to those of natural populations ofC. raciborskiispecies described in the literature. The two morphotypes produced only straight trichomes. During the study (February 2000–September 2001), this species occurred as a codominant withMicrocystis spp., and a peak was observed during the autumn (November 2000) with a remarkable density estimated to be 43 × 105trichomes/L. However, difficulty in isolating and culturing these two morphotypes limited the evaluation of their toxic potential. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 541–543, 2004.
Effect of metal stearate antacid on the melt stabilization performance of phenolic/phosphite antioxidants in metallocene LLDPE. Part 1: Melt processing stability
Authors: Hoàng Eric M. , Liauw Christopher M. , Allen Norman S. , Fontán Eusebio , Lafuente Pilar
Published: September 2004

The influence of metal stearates on the melt stabilization performance of combinations of phenolic and phosphite antioxidants in a metallocene LLDPE (mLLDPE) has been investigated. This study focused on the effect of both the origin of the stearine blend (i.e., vegetable or animal) used in the formation of the metal stearates and the type of metal stearate (i.e., calcium and zinc stearate). A multiple extrusion experiment was carried out and melt stabilization performance was monitored by melt flow rate (MFR) measurements. The level of consumption of antioxidants was evaluated by HPLC analysis of solvent extracts. Although antagonism was observed with all formulations containing metal stearates, a noticeably greater detrimental effect was apparent with metal stearates based on the vegetable derived stearine blend. Furthermore, it was apparent that the vegetable zinc stearate had a greater detrimental effect than the calcium stearate equivalent. The presence of impurities such as peroxides and metal oxides in the metal stearates investigated was believed to account for the antagonism observed. J. Vinyl Addit. Technol. 10:137–143, 2004. © 2004 Society of Plastics Engineers.
Personal and service mobility in ubiquitous computing environments
Authors: El‐Khatib K. , Zhang Zhen E. , Hadibi N. , Bochmann G. v.
Published: September 2004

Ubiquitous computing environment is defined by the shift of computing technology from the desktop to the background. One of its most notable attributes is its potential to extend the scope of service and personal mobility. This paper describes an agent‐based architecture that brings personal and service mobility to the ubiquitous computing environment. A software agent, running on a portable device carried by the user, leverages the existing service discovery protocols to learn about all services available in the vicinity of the user. Short‐range wireless technology such as Bluetooth can be used to build a personal area network connecting only devices that are close enough to the user. Acting on behalf of the user and based on a number of aspects, the software agent runs a quality of service (QoS) negotiation and selection algorithm to select the most appropriate available service(s) to be used for a given communication session. The software agent selects as well the configuration parameters for each service. The proposed architecture supports also service hand‐off to recompense for service volatility during user movement. Copyright © 2004 John Wiley & Sons, Ltd.
ARLP: an adaptive link layer protocol to improve TCP performance over wireless fading channels
Authors: Lin Haitao , Das Sajal K.
Published: September 2004

Improving the performance of Internet services is essential for future generation wireless networks. However, the correlated fading channels are found to be very unfriendly to transmission control protocol (TCP) performance in such networks. The variation in fading rate brings further challenge to wireless networks when supporting Internet applications, most of which run TCP as the transport layer protocol. In this paper, we first analytically study the performance of different radio link protocol (RLP) retransmission schemes in supporting TCP. In particular, we investigate the key quality of service (QoS) parameters of RLP such as average delay, delay variance and recovery rate of lost frames. Our analytical and simulation results show that a single retransmission scheme does not yield the best performance for different fading rates. To address this problem, we propose an adaptive radio link protocol (ARLP) that dynamically estimates the channel fading rate and also adaptively chooses those retransmission schemes that best fit the estimated fading rate. The performance of ARLP is evaluated in terms of response time (the time ARLP takes to respond to fading rate change), throughput improvement and energy consumption. The results show that ARLP can improve the performance of a particular mobile host as well as the total throughput of wireless networks, at the cost of a little extra energy consumption at low frame error rate. On the other hand, at high frame error rate, ARLP saves energy because of fewer retransmissions. Copyright © 2004 John Wiley & Sons, Ltd.
TCP congestion window evolution and spatial reuse in MANETs
Authors: Papanastasiou S. , Ould‐Khaoua M.
Published: September 2004

A number of recent research studies have explored ways to improve TCP throughput in mobile ad hoc networks by improving its interaction with the IEEE 802.11 medium access control (MAC) layer. In particular, the hidden terminal effects caused by interference can impact TCP performance dramatically and have been dealt with in the past by restricting the maximum sending window size. We have developed a TCP variant, which instead, adjusts the sending rate increase to achieve competitive goodput for TCP connections. Extensive simulation experiments indicate that a slower sending rate increase during the congestion avoidance phase of TCP leads to improved performance for TCP Reno while eliminating the negative effects inherent in restricting the maximum sending window size. This work discusses the applicability of our TCP oriented solution to the hidden terminal effect, includes a performance comparison against existing solutions and discusses its performance merits under various mobility conditions. Copyright © 2004 John Wiley & Sons, Ltd.
Li (i = 1, 2, 3) sub‐shell fluorescence yields for 79Au, 80Hg and 81Tl
Authors: Sharma Manju , Singh Prem , Shahi J. S. , Mehta D. , Singh Nirmal
Published: September 2004

The Li (i = 1, 2, 3) sub‐shell x‐ray fluorescence yields (ωi) for 79Au, 80Hg and 81Tl were deduced from the measured cross‐sections for the Li (i = 1, 2, 3) sub‐shell x‐rays following ionization by 59.54 keV γ‐rays (B < Einc < BK) and for the L3 sub‐shell x‐rays following ionization by Rb K x‐rays (B < EKα < B, B < EKβ < BK), where B is the K shell/Li sub‐shell ionization threshold of the target element. An energy‐dispersive x‐ray fluorescence setup, involving photon sources consisting of a 241Am annular source in the direct and secondary excitation modes along with RbCl secondary exciter and an Si(Li) detector, was used for the measurements. The measured ω2 and ω3 values exhibit good agreement with those based on the relativistic Dirac–Hartree–Slater (RDHS) calculations, while the ω1 values are found to be higher by ∼25%. The present data indicate that the L1–L3 Coster–Kronig yield f13 based on the RDHS calculations are overestimated. Copyright © 2004 John Wiley & Sons, Ltd.
Relationships across multiple settings: An overview
Authors: Noam Gil G. , Fiore Nina
Published: September 2004

The quality and perception of the relationship between patient and therapist, student and teacher, mentee and mentor, and youth and youth worker is the most critical determinant of success in a myriad of fields.
Studying relationships in psychotherapy: An untapped resource for youth mentoring
Authors: Spencer Renée
Published: September 2004

The core elements of effective psychotherapy may be key ingredients of effective mentoring relationships as well.
Type II phosphoinositide 5‐phosphatases have unique sensitivities towards fatty acid composition and head group phosphorylation
Authors: Schmid Annette C. , Wise Helen M. , Mitchell Christina A. , Nussbaum Robert , Woscholski Rüdiger
Published: September 2004

The catalytic properties of the type II phosphoinositide 5‐phosphatases of Lowe's oculocerebrorenal syndrome, INPP5B, Synaptojanin1, Synaptojanin2 and SKIP were analysed with respect to their substrate specificity and enzymological properties. Our data reveal that all phosphatases have unique substrate specificities as judged by their corresponding K
M and V
Max values. They also possessed an exclusive sensitivity towards fatty acid composition, head group phosphorylation and micellar presentation. Thus, the biological function of these enzymes will not just be determined by their corresponding regulatory domains, but will be distinctly influenced by their catalytic properties as well. This suggests that the phosphatase domains fulfil a unique catalytic function that cannot be fully compensated by other phosphatases.
Ratjadone and leptomycin B block CRM1‐dependent nuclear export by identical mechanisms
Authors: Meissner Torsten , Krause Eberhard , Vinkemeier Uwe
Published: September 2004

Research on the export of proteins and nucleic acids from the nucleus to the cytoplasm has greatly gained from the discovery that the actinobacterial toxin leptomycin B (LMB) specifically inactivates the export receptor chromosomal region maintenance 1 (CRM1). Recently, it was shown that myxobacterial cytotoxins, named ratjadones (RATs), also bind to CRM1 and inhibit nuclear export. However, the reaction mechanism of RATs was not resolved. Here, we show that LMB and RAT A employ the same molecular mechanism to inactivate CRM1. Alkylation of residue Cys528 of CRM1 determines both LMB and RAT sensitivity and prevents nuclear export of CRM1 cargo proteins.
Synergetic inhibition of metal ions and genistein on α‐glucosidase
Authors: Wang Yufang , Ma Lin , Li Zhong , Du Zhiyun , Liu Zhong , Qin Jiangke , Wang Xiaodong , Huang Zhishu , Gu Lianquan , Chen Albert S.C.
Published: September 2004

Inhibition of metal ions and synergetic inhibition of metal ions/genistein on α‐glucosidase activity has been investigated. We have examined the inhibitory effect of Cu2+, Ni2+, Mg2+, Fe2+, Hg2+, Zn2+, Ca2+, Pb2+, Ag+, V5+, V4+ and Mn2+ ions. The results show that the nature of the inhibition was reversible, slow‐binding, non‐competitive, and the K

i
values of some ions such as Cu2+, Ni2+ and Zn2+ range from 10−5 to 10−6 M. Moreover, synergetic inhibitory effect of metal ions and genistein on α‐glucosidase were studied with kinetics method. It is concluded that the inhibitory effect was much greater when both of them were added to the reactant solution simultaneously than that they were added, respectively, which suggests that the inhibitors seem to bind to the different sites of α‐glucosidase at the same time. Furthermore, the mechanism of the synergetic inhibition was examined by spectrophotometry.