bluuebunny/crossref_metadata_2025 huggingface dataset:
Nylon Based Nanocomposites: Influence of Calcium Carbonate Nanoparticles on the Thermal Stability
Authors: Avella Maurizio , Carfagna Cosimo , Cerruti Pierfrancesco , Errico Maria Emanuela , Gentile Gennaro
Published: March 2006

In this paper thermal and thermo‐oxidative stability of nylon 6 based nanocomposites containing up to 5% by weight of fatty acid coated calcium carbonate (CaCO3) nanoparticles is studied. Thermal stability of compression‐moulded samples was evaluated by thermogravimetric analysis (TG) under air and nitrogen atmosphere. Kinetic analysis of TG data was performed by using the Flynn‐Wall‐Ozawa method. Results show that the presence of coated nanoparticles adversely affects the thermal and thermo‐oxidative stability of nylon 6. Kinetic analysis shows that a complex, multi‐step decomposition process occurs. Moreover, the presence of nanoparticles do not affect the rate limiting step of nylon 6 decomposition in air, while under nitrogen atmosphere the decomposition process occurs through a diffusion‐driven regime in presence of high amounts of CaCO3.
Nylon 6/Calcium Carbonate Nanocomposites: Characterization and Properties
Authors: Avella Maurizio , Errico Maria Emanuela , Gentile Gennaro
Published: March 2006

Two polymorphic modifications of calcium carbonate nanoparticles (calcite and aragonite) characterized by different shape and coated with fatty acids were used as reinforcement phases of Nylon 6. Nylon 6 based nanocomposites filled with 1% and 5% by weight of calcite and aragonite were prepared by melt mixing. Morphological analysis performed on the fractured surface of nanocomposites showed that the coating agent permits to obtain uniform and fine nanoparticles dispersion. DMTA analysis revealed that nanoparticles increase the glass transition temperature of Nylon 6 up to 12 °C in the case of calcite, while a less pronounced increase was recorded for aragonite. Finally, structural analyses (FT‐IR and WAXS) underlined that calcite nanoparticles promote and stabilize the γ‐crystalline form of Nylon 6, while in the case of aragonite nanofillers the α‐crystalline form was still dominant.
Urea‐Formaldehyde Microcapsules Containing an Epoxy Resin: Influence of Reaction Parameters on the Encapsulation Yield
Authors: Cosco Simona , Ambrogi Veronica , Musto Pellegrino , Carfagna Cosimo
Published: March 2006

In this work urea‐formaldehyde microcapsules containing an epoxy resin are prepared by in situ polymerization of monomers in an oil‐in‐water emulsion. Scanning electronic microscopy (SEM) was performed to investigate on microcapsule size and surface morphology. Calorimetric and spectroscopic analyses were carried out with the aim of evaluate the encapsulation yield and the shell features. Factors determining the microencapsulability of the core material were described. In particular, our interest was devoted to a better understanding of the influence of the reaction parameters on the microcapsule properties. It was found that the encapsulation yield as well as the extent of urea‐formaldehyde polymerization depends on the reaction temperature and the stirring speed.
Modification of Cross‐Linked Rubber Particles by Free Radical Polymerization
Authors: Coiai Serena , Passaglia Elisa , Ciardelli Francesco , Tirelli Diego , Peruzzotti Franco , Resmini Emiliano
Published: March 2006

The synthesis of polystyrene chains covalently bound to the surface of cross‐linked rubber particles from recycled tires (ground tire rubber, GTR) was investigated via free radical polymerization in situ by using azobisisobutyronitrile (AIBN) and dibenzoyl peroxide (BPO) as initiators. Indeed, the graft polymerization provides a significant route to modify the physical and chemical properties of these particles allowing to improve their compatibility with other polymers. Polymerization reactions were carried out in bulk by changing the styrene/GTR ratio as well as the amount of free radical initiator. Appreciable amounts of polystyrene (PS) were grafted on GTR when BPO was used as confirmed by particle characterizations.
Elastomeric Compounds with Silica. Lower Hysteresis in the Presence of Functionalised Isoprene Oligomers
Authors: Galimberti Maurizio , Melillo Gianluca , Baione Francesca , Negroni Fabio , Pennati Simone , Spadacini Laura , Di Silvestro Giuseppe
Published: March 2006

Silica as reinforcing filler brings about a low hysteresis in elastomeric compounds. Aim of this work was to promote a better silica‐elastomer interaction by using, as minor ingredients of a compound, isoprene oligomers having a functional group as the chain end. The effect of the functionality was investigated by analysing the complex viscosity of silica‐oligomers binary mixtures as well as the morphological and rheological properties of masterbatches and compounds based on isoprene rubbers. A better silica dispersion and a lower Payne effect were clearly observed in the presence of functionalized oligomers.
Chemical Functionalisation of Vinyl Polymers to Obtain Heparin‐Like Materials
Authors: Lanciotti Stefano , Bellusci Mariangela , Francolini Iolanda , Ruggeri Valeria , Piozzi Antonella
Published: March 2006

Vinyl polymers such as poly(ethylene‐co‐vinyl alcohol) (EVAL) and polyallylamine (PALA) both commercially available were chemically modified by introduction of carboxylic and sulfonate groups to obtain polymeric materials with improved haemocompatibility. The introduction of carboxyl groups was carried out by reaction of EVAL's hydroxy groups with acrylonitrile followed by basic hydrolysis of CN groups. Amino groups of PALA were transformed into sulfonate groups by reaction with pyridine‐SO3 complex. Influence of reagents molar ratio, temperature and reaction time on the carboxylation degree was evaluated. In particular, yields of 86% (EVAL‐CN 0.52) and 30% (EVALCOOH 0.16) were obtained for the cyanoethylation and the hydrolysis reaction of the CN groups, respectively, whereas a sulfonation of 24% of the PALA amino groups was found. The functionalised polymers were characterized by physicochemical measurements. Preliminary biological tests proved the importance of strong acidic groups on the anticoagulant properties of the polymeric materials.
Neuronal activity of the zona incerta in Parkinson's disease patients
Authors: Merello Marcelo , Tenca Eduardo , Cerquetti Daniel
Published: March 2006

The objective of this study was to describe the firing characteristics of the zona incerta (ZI) in Parkinson's disease patients. The ZI constitutes a band of gray matter lying dorsal to the subthalamic nucleus, whose firing properties have not been well defined in humans yet. ZI proved to become hyperactive in 6‐OHDA–lesioned rats as compared to normal rats, and regarding these noticeable changes in the discharge patterns it was suggested that ZI could be a putative target for the surgical treatment of Parkinson's disease. Twelve patients who underwent microrecording‐guided subthalamic surgery consented to the study. Neurons from different tracts were classified as belonging to the ZI according to their firing features, background extracellular activity, anatomical mapping of trajectories, and atlas confirmation. Fifty‐nine neurons were classified as belonging to ZI. The mean firing rate proved to be 29.5 Hz, with a broad dispersion band, even covering subthalamic nucleus (STN) frequency ranges. Pattern analysis showed heterogeneous neuronal signals ranging from tonic to burst and paused neurons. A decrease in extracellular background activity in the defined ZI was also observed. Five of the recorded neurons showed rhythmical spike trains with oscillations of 8 to 14 Hz, and two units were found to discharge trains at 4 Hz. None of the recorded ZI neurons responded to proprioceptive maneuvers. ZI presented firing activities with a broad spectrum in terms of frequency and tonicity. It is differentiated from STN recordings in Parkinson's disease patients mainly because of absent proprioceptive‐related units and diminished extracellular background activity. © 2006 Movement Disorder Society
Unilateral pallidotomy for hemidystonia
Authors: Alkhani Ahmed , Bohlega Saeed
Published: March 2006

Hemidystonia is a clinical presentation of many pathological conditions that can affect the basal ganglia. It is usually a refractory condition to current medical treatment. Recently, stereotactic procedures such as radiofrequency lesioning or deep brain stimulation provided hope for patients with dystonia; we are reporting the clinical outcome of a patient with hemidystonia treated with unilateral pallidotomy. A 15‐year‐old boy with no family history of movement disorders and normal perinatal history is presented. He started to have progressive dystonic contractions in the right hand and extended to involve both the upper and lower extremities in the right side over a period of 3 years. He was subjected to a left‐sided posteroventral pallidotomy. Postoperatively, his hemidystonia improved over a period of a few weeks. The Unified Dystonia Rating Scale improved by 84%. He maintained the improvements for the 2‐year postoperative follow‐up period. No complications were encountered. Clinical presentation, surgical techniques, and surgical results are presented. In conclusion, hemidystonia may significantly respond to a contralateral posteroventral pallidotomy. © 2006 Movement Disorder Society
Hölder continuity for two‐phase flows in porous media
Authors: Yeh Li‐Ming
Published: March 2006

This work is to prove the Hölder continuity of the solutions of the degenerate differential equations describing two‐phase, incompressible, immiscible flows in porous media. The differential equations allow degeneracy at two end points and the assumption on mild degeneracy is not required in this study. The regularity result is proved by an alternative argument. Uniqueness of the weak solutions of the differential equations is a direct consequence from this Hölder continuity. Copyright © 2006 John Wiley & Sons, Ltd
2,3,7,8‐Tetrachlorodibenzo‐p‐dioxin induced cytochrome P450s alter the formation of reactive oxygen species in liver cells
Authors: Knerr Stefanie , Schaefer Johanna , Both Saskia , Mally Angela , Dekant Wolfgang , Schrenk Dieter
Published: March 2006

2,3,7,8‐Tetrachlorodibenzo‐p‐dioxin (TCDD) was classified by the International Agency for Research on Cancer as a carcinogen in humans. It acts through an aryl hydrocarbon receptor‐mediated mechanism, inducing the transcription of numerous genes, including various cytochrome P450s (CYPs – CYP1A1, 1A2, 1B1). Induction of CYPs may lead to genotoxicity by generating reactive oxygen species (ROS) which can damage DNA directly and/or via the generation of reactive metabolites. We determined ROS formation with the 2′,7′‐dihydrodichlorofluorescein diacetate fluorescence assay after incubation of HepG2 hepatoma cells or primary rat hepatocytes with TCDD. The amount of 8‐oxo‐2′‐deoxyguanosine (8‐oxo‐dG) in DNA was measured using HPLC‐MS/MS, the amount of CYP1A1 protein by Western blotting. The catalytic activity of CYP1A enzymes was determined as 7‐ethoxyresorufin‐O‐deethylase (EROD) activity. Incubation of cells with TCDD for 48 h caused increased levels of ROS in primary rat hepatocytes as well as increased levels of 8‐oxo‐dG in DNA compared to untreated cells. In the HepG2 cell line no significant effects were observed for both ROS formation and 8‐oxo‐dG levels. Both effects were in good agreement with the extent of induction of CYP1A1 protein and EROD activity, suggesting that CYP1 induction is a major source of ROS formation in TCDD‐treated hepatocytes.
Phosphonium‐modified layered silicate epoxy resins nanocomposites and their combinations with ATH and organo‐phosphorus fire retardants
Authors: Schartel Bernhard , Knoll Uta , Hartwig Andreas , Pütz Dirk
Published: March 2006

Phosphonium‐modified layered silicate epoxy resin nanocomposites were evaluated by testing the thermal/thermo‐mechanical properties [differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), torsional pendulum, Sharpy toughness], flammability (limiting oxygen index LOI) and fire behavior (cone calorimeter with different irradiations). The morphology of the composites was determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The drying conditions of phosphonium‐modified layered silicate were varied in order to improve the nanocomposite formation and properties. The results were compared with using a commercial ammonium‐modified montmorillonite. Enhanced nanocomposite formation was found for the commercial systems due to the amount of excess surfactant, but this effect was overcompensated through the advanced morphology of the phosphonium‐modified systems. Several fire retardancy mechanisms and their specific influence on the different fire properties, such as ignitability, flammability, flame spread, total heat release (fire load), and the production of CO and smoke were discussed comprehensively. The main mechanism of layered silicate is a barrier formation influencing the flame spread in developing fires. Several minor mechanisms are significant, but important fire properties such as flammability or fire load are hardly influenced. Hence combinations with aluminum hydroxide and organo‐phosphorus flame retardants were evaluated. The combination with aluminum hydroxide was a promising approach since it shows superposition in properties such as the fire load and only in some properties very little antagonism. The combination with an organo‐phosphorus flame retardant disillusions, since it was characterized mainly by antagonism. Copyright © 2006 John Wiley & Sons, Ltd.
Survivin: An inhibitor of apoptosis in pediatric cancer
Authors: Fangusaro Jason R. , Caldas Hugo , Jiang Yuying , Altura Rachel A.
Published: March 2006

Survivin is an inhibitor of apoptosis protein (IAP) expressed in a large number of adult malignancies. Its expression levels correlate with more aggressive disease and poor clinical outcome in many of these tumors. As its expression is restricted in normal adult differentiated tissues, it has become of great interest as both a tumor prognostic marker and as a potential biologic target for future anti‐cancer therapies. Survivin expression and Survivin‐based therapies have been examined in many of the more common pediatric malignancies. We present an overview of Survivin function and current research exploring its biologic and therapeutic roles in pediatric tumors. Pediatr Blood Cancer © 2006 Wiley‐Liss, Inc.
Surface‐initiated nitroxide‐mediated polymerization: a tool for hybrid inorganic/organic nanocomposites ‘in situ’ synthesis
Authors: Ghannam Leïla , Parvole Julien , Laruelle Gael , Francois Jeanne , Billon Laurent
Published: March 2006

Hybrid silica particles comprised of an inorganic core and an organic polymer shell can be synthesized by surface‐initiated nitroxide‐mediated polymerization (SINMP) in the presence of a grafted alkoxyamine as initiator. The layer of initiator molecules attached or adsorbed to the particles surface is based on a nitroxide group. The synthesis and characterization of these alkoxyamine structures are briefly described. The grafted initiator particles are studied in order to determine the nature of the anchorage sites and the grafting density. With a stable radical or nitroxide as chain‐growth moderator tethered to the inorganic core, it was demonstrated that the grafting from or to SINMP exhibits a control character with a very low polydispersity and good agreement between theoretical/experimental molecular weights. A comparative review of different alkoxyamines with a bimolecular system based on a grafted azoic initiator in the presence of an acyclic β‐phosphonylated nitroxide called SG1 is also described. Moreover, original methods for the synthesis of alkoxyamine grafted surface by in situ trapping of carbon radicals and some new developments for colored pigments will be reported. These topics could be one of the directions of the field in the next years. Copyright © 2006 Society of Chemical Industry
Modification of Nafion membrane using poly(4‐vinyl pyridine) for direct methanol fuel cell
Authors: Woong Jeon Chan , Venkataramani Sriram , Kim Sung Chul
Published: March 2006

Perfluorinated membrane such as Nafion (from Du‐Pont) has been used as a polymer electrolyte membrane. Nafion 117 membrane, which was usually used as the electrolyte membrane for the polymer electrolyte membrane fuel cell (PEMFC), was modified by using poly(4‐vinyl pyridine) (P4VP) to reduce the methanol crossover, which cause fuel losses and lower power efficiency, by the formation of an ionic crosslink structure (sulfonic acid‐pyridine complex) on the Nafion 117 surface. Nafion film was immersed in P4VP/N‐methyl pyrrolidone (NMP) solution. P4VP weight percent of modified membrane was controlled by changing the concentration of P4VP/NMP solution and the dipping time. P4VP weight percent increased with increasing concentration of dipping solution and dipping time. The thickness of the P4VP layer increased with increasing concentration of dipping solution and dipping time when the concentration of the dipping solution was low. At high P4VP concentration, the thickness of the P4VP layer was almost constant owing to the formation of acid–base complex which interrupted the penetration of P4VP. FTIR results showed that P4VP could penetrate up to 30 µm of Nafion 117 membrane. Proton conductivity and methanol permeability of modified membrane were lower than those of Nafion 117. Both decreased with increasing concentration of dipping solution and dipping time. Methanol permeability was observed to be more dependent on the penetration depth of P4VP. Water uptake of the modified membrane, the important factor in a fuel cell, was lower than that of Nafion 117. Water uptake also decreased with increasing of P4VP weight. On the basis of this study, the thinner the P4VP layer on the Nafion 117 membrane, the higher was the proton conductivity. Methanol permeability decreased exponentially as a function of P4VP weight percent. Copyright © 2006 Society of Chemical Industry
Highly magnetic latexes from submicrometer oil in water ferrofluid emulsions
Authors: Montagne Franck , Mondain‐Monval Olivier , Pichot Christian , Elaïssari Abdelhamid
Published: March 2006

The synthesis of functionalized submicrometer magnetic latex particles is described as obtained from a preformed magnetic emulsion composed of organic ferrofluid droplets dispersed in water. Composite (polystyrene/γ‐Fe2O3) particles were prepared according to a two‐step procedure including the swelling of ferrofluid droplets with styrene and a crosslinking agent (divinyl benzene) followed by seeded emulsion polymerization with either an oil‐soluble [2,2′‐azobis(2‐isobutyronitrile)] or water‐soluble (potassium persulfate) initiator. Depending on the polymerization conditions, various particle morphologies were obtained, ranging from asymmetric structures, for which the polymer phase was separated from the inorganic magnetic phase, to regular core–shell morphologies showing a homogeneous encapsulation of the magnetic pigment by a crosslinked polymeric shell. The magnetic latexes were extensively characterized to determine their colloidal and magnetic properties. The desired core–shell structure was efficiently achieved with a given styrene/divinyl benzene ratio, potassium persulfate as the initiator, and an amphiphilic functional copolymer as the ferrofluid droplet stabilizer. Under these conditions, ferrofluid droplets were successfully turned into superparamagnetic polystyrene latex particles, about 200 nm in size, containing a large amount of iron oxide (60 wt %) and bearing carboxylic surface charges. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2642–2656, 2006
DFT calculations of the ionization potentials and electron affinities of serinamide
Authors: Lu Jinfeng , Zhu Songling , Zhou Zhengyu , Wu Qunyan , Zhao Gang
Published: March 2006

Adiabatic and vertical ionization potentials (IPs) and valence electron affinities (EAs) of serinamide in the gas phase have been determined using density functional theory (DFT) B3LYP, B3P86, and B3PW91 methods with the 6‐311++G** and 6‐311G** basis sets, respectively. IPs and EAs of serinamide in solution have been calculated with the B3LYP method using the 6‐311++G** and 6‐311G** basis sets. Eight possible conformers of serinamide and its charged states in the gas phase have been optimized employing the DFT B3LYP method with 6‐311++G** and 6‐311G** basis sets, respectively. All the adiabatic and vertical ionization potentials (AIPs and VIPs) of eight serinamide conformers in our work are positive values, whether in the gas phase or in solutions; the IPs in solutions are smaller than the results in the gas phase and decrease with increased dielectric constants in solutions. This finding indicates that the cationic states in solutions are more stable than those in the gas phase. All EAs of eight serinamide conformers are negative values in the gas phase, indicating that the anionic states are unstable with respect to electron autodetachment, both adiabatically and vertically. In contrast, all other adiabatic electron affinities (AEAs) are negative values in solutions except for 6S in water; 7S in chloroform, acetone, and water; and 8S in acetone and water, and increase with increasing of dielectric constants in solutions. All vertical electron affinities (VEAs) are negative values in solutions; however, no good rule has been found for these values in solutions. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Theoretical study of the reaction mechanism of proton transfer in glycinamide
Authors: Zhang Liqun , Zhou Zhengyu , Du Dongmei , Yuan Pei
Published: March 2006

To investigate the tautomerism of glycinamide that is induced by proton transfer, we present detailed theoretical studies on the reaction mechanism of both the isolated gas phase and H2O‐assisted proton transfer process of glycinamide, using density functional theory calculations by means of the B3LYP hybrid functional. Twenty‐six geometries, including 10 significant transition states, were optimized, and these geometrical parameters are discussed in detail. The relative order of the activation energy for hydrogen atom transfer of all the conformers has been systematically explored in this essay. For the amido hydrogen atom transfer process, the relative order of the activation energy is: IV < II < III < I, while in the carbonic hydrogen atom transfer process, the relative order is IV > II > III > I. Meanwhile, the most favorable structure for both the amido hydrogen atom transfer and the carbonic hydrogen atom transfer has been found. The involvement of the water molecule not only can stabilize the transition states and the ground states, but can also reduce the activation energy greatly. The superior catalytic effect of H2O has been discussed in detail. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Evaluation of DFT methods for computing the interaction energies of homomolecular and heteromolecular dimers of monosubstituted benzene
Authors: Godfrey‐Kittle Andrew , Cafiero Mauricio
Published: March 2006

We present density functional theory (DFT) interaction energies for the sandwich and T‐shaped conformers of substituted benzene dimers. The DFT functionals studied include TPSS, HCTH407, B3LYP, and X3LYP. We also include Hartree–Fock (HF) and second‐order Møller–Plesset perturbation theory calculations (MP2), as well as calculations using a new functional, P3LYP, which includes PBE and HF exchange and LYP correlation. Although DFT methods do not explicitly account for the dispersion interactions important in the benzene–dimer interactions, we find that our new method, P3LYP, as well as HCTH407 and TPSS, match MP2 and CCSD(T) calculations much better than the hybrid methods B3LYP and X3LYP methods do. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Kinetics and structural aspects of the cisplatin interactions with guanine: A quantum mechanical description
Authors: Costa Luiz Antônio S. , Hambley Trevor W. , Rocha Willian R. , De Almeida Wagner B. , Dos Santos Hélio F.
Published: March 2006

The interaction of cisplatin with guanine DNA bases has been investigated using ab initio Hartree–Fock (HF) and density functional levels of theory in gas phase and aqueous solution. The overall process was divided into three steps: the reaction of the monoaqua [Pt(NH3)2Cl(H2O)]+ species with guanine (G) (reaction 1), the hydrolysis process yielding the adduct [Pt(NH3)2(G) (H2O)]2+ (reaction 2) and the reaction with a second guanine leading to the product [Pt(NH3)2(G)2]2+ (reaction 3). The functionals B3LYP, BHandH, and mPW1PW91 were used in the present study, to develop an understanding of the role of the distinct models. The geometries presented for the intermediate structures were obtained by IRC calculations from the transition state structure for each reaction. The structural analysis for the intermediates and transition states showed that hydrogen bonds with the guanine O6 atom play an important role in stabilizing these species. The geometries were not very sensitive to the level of theory applied with the HF level, giving a satisfactory overall performance. However, the energy barriers and the rate constants were found to be strongly dependent on the level of calculation and basis set, with the DFT calculations giving more accurate results. For reaction 1 the rate constant calculated in aqueous solution at PCM‐BHandH/6‐311G* (k1 = 7.55 × 10−1 M−1 s−1) was in good agreement with the experiment (5.4 × 10−1 M−1 s−1). The BHandH/6‐31G* calculated gas phase rate constants for reactions 2 and 3 were: k2 = 0.9 × 10−6 M−1 s−1 and k3 = 2.99 × 10−4 M−1 s−1 in fairly good accordance with the experimental findings for reaction 2 (1.0 × 10−6 M−1 s−1) and reaction 3 (3.0 × 10−4 M−1 s−1). © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Restricted and unrestricted Hartree–Fock approaches applied to spherical quantum dots in a magnetic field
Authors: Destefani C. F. , Vianna J. D. M. , Marques G. E.
Published: March 2006

The Roothaan and Pople–Nesbet approaches for real atoms are adapted to quantum dots in the presence of a magnetic field. Single‐particle Gaussian basis sets are constructed, for each dot radius, under the condition of maximum overlap with the exact functions. The chemical potential, charging energy, and total spin expected values are calculated, and we have verified the validity of the quantum dot energy shell structure as well as Hund's rule for electronic occupation at zero magnetic field. At finite field, we have observed the violation of Hund's rule and studied the influence of magnetic field on the closed and open energy shell configurations. We have also compared the present results with those obtained within the LS‐coupling scheme for low electronic occupation numbers. We focus only on ground‐state properties and consider quantum dots populated up to 40 electrons, constructed by GaAs or InSb nanocrystals. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
An improved non‐sequential multi‐input multi‐output quantitative feedback theory design methodology
Authors: L. Kerr Murray , Jayasuriya Suhada
Published: March 2006

This paper presents an improved non‐sequential multi‐input multi‐output (MIMO) Quantitative Feedback Theory (QFT) design methodology for uncertain systems. A non‐sequential MIMO QFT stability theorem is derived that serves as the basis for an improvement of the design methodology, whereby it can be successfully applied to non‐minimum phase systems, albeit with a degree of conservatism partially inherent in independent and decentralized design methodologies. The results reduce the conservatism in a non‐sequential MIMO QFT design and provide insight into the plant cases for which the methodology can be successfully applied. Copyright © 2006 John Wiley & Sons, Ltd.
Physiographic characteristics of bridge‐stream intersections
Authors: Johnson Peggy A.
Published: March 2006

Bridges that cross streams can be greatly affected by channel instabilities, such as channel widening, lateral migration and channel bed degradation. Attention to channel conditions in the vicinity of bridges is an important aspect of bridge maintenance and safety. Channel stability is also critical to goals of multi‐objective river management. Given that channel stability is important for both river management and the structural stability of bridges, any river management scheme should consider the stability of bridge‐stream intersections. In this paper, the characteristics of bridge‐stream intersections across the United States are described based on existing literature and recent field observations. A set of recommendations for addressing and improving channel stability at bridges is suggested, including: (1) controlling water and sediment discharges at the catchment level; (2) revegetating channel banks with woody vegetation; (3) reshaping the channel cross‐section to a more stable, configuration; (4) removing disturbances from the stream channel, such as cattle and (5) using structures to control flow near channel beds and banks. The physiographic setting is a factor in the solution of at least the first three suggestions in this list. Attention to the physical characteristics of bridge‐stream intersections in the various physiographic regions can lead to sustainable solutions for stabilizing channels at bridge‐stream intersections. Copyright © 2006 John Wiley & Sons, Ltd.
Petrological evidence for crustal thickening and extension in the Serre granulite terrane (Calabria, southern Italy)
Authors: ACQUAFREDDA PASQUALE , FORNELLI ANNAMARIA , PAGLIONICO ANTONIO , PICCARRETA GIUSEPPE
Published: March 2006

The paper presents the metamorphic trajectory recorded by metapelitic migmatites of the upper part of the Hercynian lower continental crust of the Serre (southern Calabria, Italy). The relict minerals, reaction textures and phase equilibria define a clockwise P–T path. The prograde metamorphism from temperature of about 500°C and pressure of 4–5 kbar to T<700°C and P∼8 kbar stabilized the assemblage Grt+Ky+Bt+Ms(Si/11ox=3.26–3.29) in the uppermost metapelites of the profile. Progressive heating led to H2O-fluxed and dehydration melting first of Ms, then of Bt at T<700°C in the stability field of sillimanite. This process was followed by nearly isothermal decompression producing additional melt with a transition from Grt to a Grt+Crd stability field. Further decompression caused the formation of Crd-corona around garnet. Nearly isobaric cooling led to rehydration and retrogression across the stability field of andalusite up to the stability field of kyanite. The lowermost metapelites of the studied profile have lost most of the memory of the prograde P–T path; they record decompression and cooling. High-temperature mylonites occur in which boudinage, elongation and pull-aparts characterize the porphyroclasts. The pull-aparts in the high-T mylonites are filled with low-P minerals (Crd+Spl). The Hercynian metamorphic trajectory and the microtextures are consistent with crustal thickening and subsequent extensional regime. During extension, an important tectonic denudation probably caused the isothermal decompression. Extension also occurred in post-Hercynian times as documented by pull-aparts in sillimanite porphyroclasts filled with chloritoid within a low-grade mylonite.
Lithofacies and fluvial–lacustrine environments of the Palaeogene Sevkhuul and Ergil members (Ergiliin Zoo Formation, South Gobi, Mongolia)
Authors: DILL H. G. , KHISHIGSUREN S. , BULGAMAA J. , BOLORMA KH. , MELCHER F.
Published: March 2006

The clastic sequence of the Ergiliin Zoo Formation stretches along the Mongolian–Chinese border in the southern Gobi Desert, Mongolia. Its members (Sevkhuul, Ergil) exposed in the Erdene Sum region are well known for their vertebrate remains of Late Eocene and Oligocene age. Based upon field work, the continental red beds were subdivided into four units described as (I) prodelta/mud-sand flat, (II) delta front, (III) delta plain and (IV) calcretes. All sub-environments are in a fluvial–lacustrine setting. Electronmicroprobe analysis, in addition to conventional thin-section examination, was applied to shed some light on the complex mineral association made up of light minerals (quartz, plagioclase, ternary feldspar, orthoclase, smectite, illite, rare palygorskite), heavy minerals (almandine–pyrope solid solution series, zoisite–epidote s.s.s.) and abundant goethite and carbonate minerals (calcite, dolomite). Igneous rocks being exposed in the source area have contributed to the formation of carbonate minerals and Mg-bearing sheet silicates during diagenesis. Higher up on the delta plain transitional between distal alluvial and deltaic deposits, fluids emerged from the distal alluvial–fluvial deposits and formed calcareous duricrusts. Drawing conclusions from the rock colour, the mineral assemblage and the palaeoecological data, the climatic conditions may be described as alternating wet and dry seasons, closely resembling those conditions of a modern savannah.
Meiofaunal community structure in three Mediterranean coastal lagoons (North Aegean Sea)
Authors: Doulgeraki S. , Lampadariou N. , Sinis A.
Published: March 2006

The higher taxonomic structure of the meiofaunal community was investigated in three eastern Mediterranean lagoons, an open (Vassova), a semi-closed (Piges) and a closed lagoon (Alykes Kitrous). In total, 22 stations representing characteristic features in each lagoon were sampled. Stations were found to support a maximum of 19 meiofaunal taxa with densities ranging from 1 to 10,000 individuals per 10 cm2. Nematodes were dominant at all sites (30–97%) except at the hypersaline sites, where ciliates outnumbered all metazoan meiofaunal taxa (53–77%). Uni- and multivariate analyses were applied to study the community structure. The number of taxa and the meiofaunal density showed strong spatial differences in all three lagoons; however, the main source of variation occurred between the semi-closed and closed lagoons. Both the meiofaunal composition and density were significantly less at the hypersaline sites which had salinity above 100 psu. The meiofaunal distribution pattern was shown to be controlled by abiotic factors, in particular vertical stratification of salinity, bottom water currents and oxygen availability at the bottom water–sediment interface. However, the distribution of feeding resources (e.g. cyanobacteria, phytodetritus) was also found to play a key role in structuring meiofaunal communities.
A parasite indirectly impacts both abundance of primary producers and biomass of secondary producers in an intertidal benthic community
Authors: Mouritsen Kim N. , Poulin Robert
Published: March 2006

The New Zealand cockle Austrovenus stutchburyi is often found stranded on the sediment surface due to infections by echinostome trematodes. High densities of heavily-infected cockles on the sediment surface affect near-seabed hydrodynamics and sedimentation and, in turn, benthic animal community structure and diversity. In a six-month field experiment on an intertidal sandflat we manipulated the density of cockle mimics on the sediment surface, and here we show that their presence had two significant impacts on community functioning. First, the benthic primary production (in terms of chlorophyll-a content) was reduced by 8–22%. Second, their presence significantly boosted (up to 5-fold) the secondary production (in terms of biomass) of Coelenterata, Nemertea, small polychaetes, small bivalves and the gastropod Diloma subrostrata. The results hence provide a field experimental example of a parasite-mediated link between diversity and productivity.
Effects of macroinfauna sediment disturbance on nematode vertical distribution
Authors: Pinto T.K. , Austen M.C. , Bemvenuti C.E.
Published: March 2006

Within a subtropical estuary in southern Brazil, an experiment was carried out to test the hypotheses that the deposit feeding macrofaunal polychaete Laeonereis acuta affects nematode community structure and the vertical distribution patterns of nematodes in sediments. Inclusion cages were deployed with two different densities of the polychaete and meiofaunal nematodes were sampled from six different vertical sediment layers: 0–1, 1–2, 2–4, 4–6, 6–8 and 8–10 cm depth. Although L. acuta did change the vertical distribution of both nematode and trophic groups in the sediment, allowing nematodes to inhabit deeper sediment layers, there were no apparent effects of different polychaete densities.
Population structure, growth and production of Laeonereis culveri (Nereididae: Polychaeta) in tidal flats of Río de la Plata estuary, Argentina
Authors: Martin J.P. , Bastida R.
Published: March 2006

A benthic survey was carried out from November 1998 to December 1999 in the tidal flats of Bahía Samborombón (Río de la Plata estuary, Argentina), in order to study the population structure, growth and secondary production of Laeonereis culveri. The samples were collected monthly in two intertidal areas with different environmental characteristics (San Clemente Creek and Punta Rasa). Growth was analysed using computer-based methods of length–frequency data (ELEFAN), and the secondary production was estimated by Crisp's and Hynes & Coleman's methods. Laeonereis culveri were recruited throughout the year, with two main peaks during spring and autumn. The autumn cohort showed growth rate (K) of 2 in San Clemente Creek and 1.8 in Punta Rasa. The seasonal oscillation of growth pointed out that worms grow very slowly during winter months. The life span of this cohort ranged from 15 to 17 months. The spring cohort showed higher growth rates in both sampled areas (K=3.3 in Punta Rasa and 3.1 in San Clemente Creek), whereas the growth oscillation showed similar values to those of the autumn cohort. The lowest growth rate was found in January and the life span was 9.5 months. The annual mean biomass in San Clemente Creek was 5.44 g m−2, with a mean production of 40.8 and 43.8 g m−2 y−1, according to the method used, and a production/biomass (P/B) ratio of 7.5 and 8 y−1 respectively. In Punta Rasa, the annual mean biomass (2.69 g m−2) and mean secondary production (19.44 and 23.61 g m−2 y−1, according to the method used) were lower than in San Clemente Creek, nevertheless the P/B ratio (7.2 and 8.7 y−1) was similar. The high secondary production and P/B ratio observed suggest that L. culveri transfer an important biomass to higher trophic levels, pointing out the very important role that this polychaete plays in the energy flux of this coastal estuarine ecosystem.
Paraonidae (Polychaeta) from western Mexico, with description of two new species
Authors: de León-González Jesús Angel , Guevara Norma Angélica Hernández , Rodríguez-Valencia José Alejandro
Published: March 2006

In the present study 23 species of paraonids from western Mexico collected from the intertidal zone to the continental shelf of Baja California Sur, Guaymas, Sonora, and Petacalco, Guerrero are reported. Eight of these species are first recorded from the Mexican coast: Aricidea (Acmira) assimilis, Aricidea (Acmira) catherinae, Aricidea (Allia) ramosa, Aricidea (Aricidea) longicirrata, Aricidea (Aricidea) minima, and Levinseniaoligobranchiata; Aricidea (Aricidea) minuta and Cirrophorusarmatus are cited for first time from the Pacific. Two new species are described. Aricidea (Aricidea) petacalcoensis sp. nov. has bifurcate antenna on prostomium without nuchal grooves, tapering branchiae in chaetigers 4–13, modified neuropodial chaetae from chaetiger 21. Cirrophorus magdalenaensis sp. nov. has prostomium without antennae, eyes or nuchal grooves, banchiae from chaetiger 5, having ten pairs, notopodial modified chaetae bayonet-shaped.
Life cycle of Capitella sp. Y (Polychaeta: Capitellidae) from Estero del Yugo, Mazatlán, Mexico
Authors: Méndez Nuria
Published: March 2006

The development of the polychaete Capitella sp. Y from Estero del Yugo, Mazatlán, Mexico was studied under culture conditions. Capitella sp. Y has a lecithotrophic development with the production of ciliated metatrochophore larvae. A high variation in size and duration of the different developmental stages was observed, as with most of the Capitella species previously described. The median survival time was estimated as six months. The Capitella sp. Y population consists of males, females and hermaphrodites (protandrous and proteroginous individuals). Differences in developmental modes among the Capitella capitata species-complex have indicated that Capitella sp. Y do not belong to any of these previously described species. This study has shown that hermaphroditism is favoured when density of individuals is low, especially in protandrous specimens. It is suggested that hermaphroditism, as well as the ability of self-fertilization observed in Capitella sp. Y enhances the success of the population in natural environments.
New species of free-living marine nematodes from the Yellow Sea, China
Authors: Huang Y. , Zhang Z.N.
Published: March 2006

Three new species of free-living marine nematodes: Oncholaimus multisetosus sp. nov., Sabatieria stenocephalus sp. nov. and Setosabatieria coomansi sp. nov. from the Yellow Sea, China are described and illustrated. The male of Oncholaimus multisetosus sp. nov. is characterized by a tail sharply constricted at the junction of the conical and cylindrical sections; two circles of 12–15 pairs of circumcloacal setae each. In the female, the conical section of the tail gradually tapers in a cylindrical section. Sabatieria stenocephalus sp. nov. is characterized by the pronounced sharp-pointed anterior body, sclerotized tooth-like front edge of buccal cavity and 15 tubular-shaped precloacal supplements with the posterior five more closely spaced. Setosabatieriacoomansi sp. nov. can be separated from the other species of the genus by the number (6–8) of cervical setae per file, the number of precloacal supplements (15) and the absence of central strips in spicules and leaf-like extensions of the cuticle lateral to the cloaca. Types are deposited in the College of Marine Life Sciences, Ocean University of China.
Lipid composition of the trophosome in the beard worm, Oligobrachia mashikoi (Pogonophora)
Authors: Mita Masatoshi , Deguchi Mariko , Sasayama Yuichi
Published: March 2006

A large quantity of triglyceride was detected histochemically in nutrient-deposit cells of the trophosome in the beard worm (Oligobrachia mashikoi). The lipid extracted from the trophosome was composed of triglyceride, several kinds of phospholipid, free fatty acid, cholesterol, and cholesterol ester. The fatty acid of the triglyceride was comprised mainly of a monoenoic type, such as palmitoleic acid (16:1) and oleic acid (18:1), which accounted for 31% and 37% of the total fatty acids, respectively. In addition, in blood triglyceride, the fatty acid composition was almost the same.
A 25-year study of climatic and density-dependent population regulation of common shrimp Crangon crangon (Crustacea: Caridea) in the Bristol Channel
Authors: Henderson P.A. , Seaby R.M. , Somes J.R.
Published: March 2006

The results of a 25-year study of the population dynamics of the common shrimp, Crangon crangon, in the Bristol Channel are presented. The population size varied seasonally, with maximum abundance occurring in early autumn at the completion of annual recruitment. The number of recruits changed greatly between years, and was positively correlated with both average water temperature from January to August, and river flow rate, and negatively correlated with the Winter North Atlantic Oscillation Index. A wide range of other physical and biotic variables was found to have no significant impact on C. crangon abundance. The positive relationship between temperature and C. crangon abundance observed for the Atlantic coast during this study is the opposite of that found for southern North Sea populations. Similar contradictory responses have been noted previously for flatfish such as sole, Solea solea. This suggests that global variables may act to produce different outcomes for Atlantic and North Sea populations of the same species. Over-winter mortality was found to vary with population size so that the adult C. crangon population in spring was found to be remarkably stable, and little influenced by temperature or other variables. The mortality rate increased with population size producing clear evidence of density-dependent control. It is suggested that this stability is linked to the constant limited availability of suitable habitat, with individuals unable to find shelter vulnerable to a range of predatory fish. Given the pivotal role of C. crangon within the northern European estuarine ecosystems, this stability may be a critical component for the overall stability of the system. A particular feature of this study was the exceptional recruitment observed in October 2002. This did not result in any subsequent increase in adult C. crangon numbers, possibly because there was a synchronous increase in a wide range of predators. While the adult population has remained stable and showed no temporal trend, there has been an increase in both the average magnitude and between year variability in recruitment, which can be related predominately to the recent increase in water temperature. The difficulty of predicting the response of this population to continued climate warming is discussed. If temperature continues to rise, the present power law describing the increase in recruitment with temperature must inevitably break down. If this were to occur, the future trajectory of the C. crangon population could not be predicted, and the continued stability of this ecosystem would no longer be assured.
Within- and between-plant distribution of harpacticoid copepods in a North Atlantic bed of Laminaria ochroleuca
Authors: Arroyo Nina Larissa , Maldonado Manuel , Walters Keith
Published: March 2006

The fauna of harpacticoid copepods associated with a North Atlantic sublittoral population of Laminaria ochroleuca in Spain was investigated. Copepods belonging to four different orders, i.e. Harpacticoida, Cyclopoida, Poecilostomatoida and Siphonostomatoida, most of which were harpacticoids belonging to 17 different families were collected. Because the family Thalestridae was particularly abundant in the samples, its members were identified down to the species level, totalling 20 species. The copepod fauna was richer and more diverse on holdfasts than on fronds, irrespective of considering the entire harpacticoid assemblage at the family level or just the family Thalestridae at the species level. The effect of these two within-plant microhabitats on the taxonomic composition of the copepod fauna was substantial, with faunal similarity between fronds of plants from different sampling quadrats being usually higher than that between the frond and the holdfast of the same plant. Thalestridae, Harpacticidae and Tisbidae predominated on the fronds, while Diosaccidae, Ameiridae and Ectinosomatidae predominated on the holdfasts. Among the thalestrids, Parathalestris clausi, Paradactylopodia sp.1, Dactylopusia tisboides, and Dactylopusia vulgaris were common species, with Parathalestris clausi being the most abundant copepod on both fronds and holdfasts. In summary, the fauna of the holdfasts consists mostly of common, eurytopic species, while the fauna of the fronds comprises rare taxa—at least within the scope of the study—with low total abundances and/or usually occurring in few plants.