bluuebunny/crossref_metadata_2025 huggingface dataset:
Respiratory Levels and Adaptations in Four Freshwater Species of Gammarus (Crustacea: Amphipoda)
Authors: Toman Mihael J. , Dall Peter C.
Published: February 2007

Respiration of four freshwater species of the amphipod crustacean Gammarus: G. fossarum, G. lacustris (river and lake), G. pulex and G. roeseli were measured in a closed, stirred respirometric chamber with a micro‐electrode. Oxygen consumption, expressed as weight‐specific oxygen uptake (Rs) in relation to decreasing oxygen concentration, varied at air saturation from 0.86 (G. lacustris, lake) to 2.06 μl O2 mg−1 AFDW h−1 (G. pulex). Rs also differed intra‐specifically among the two populations of G. lacustris.

G. lacustris (river), G. pulex and G. roeseli expressed moderate ability to regulate their oxygen consumption at decreasing oxygen concentrations, whereas the regulation ability was higher in G. lacustris (lake) and in G. fossarum, which maintain high oxygen uptake at oxygen levels >2 mg O2 l−1.

All four Gammarus species are partial regulators in response to variations in oxygen concentration. The differences between species are considered too small to account for their natural distributions. It appears that the tolerances of Gammarus species to organic pollution depend only in part on oxygen conditions.
Hydrodynamic Characteristics of Daphnia middendorffiana
Authors: Vega Marina Patricia , Clausse Alejandro
Published: February 2007

Sinking terminal velocities of D. middendorffiana (with and without tail spine) were measured and correlated with morphological parameters and water temperature. The main dimensions of the body showed positive growths rate correlations with the body weight. In turn, negative allometric variation was observed in the tail‐spine length. The density of D. middendorffiana was age specific, and decreased as the individual grew. No differences in the sinking terminal velocities and trajectories between individuals with and without tail spine were observed. The observed hydrodynamic characteristics of D. middendorffiana were simulated by means of a model based on equivalent ellipsoids and spheres. The analysis showed that the effects of shape and the body projections are negligible on the sinking rates of D. middendorffiana.
Plankton Seasonal Dynamics and Its Controlling Factors in Shallow Polymictic Eutrophic Lake Võrtsjärv, Estonia
Authors: Nõges Tiina , Kisand Veljo , Nõges Peeter , Põllumäe Arno , Tuvikene Lea , Zingel Priit
Published: February 2007

An analysis of plankton seasonal succession in large shallow eutrophic lake Võrtsjärv (270 km2, mean depth 2.8 m, max. depth 6 m) is presented. Weekly samples for 1995 have been analysed using the PEG model approach. In winter, light was the main factor controlling phytoplankton growth. In early spring phytoplankton was mainly resource‐controlled, competition for phosphorus being the main driving force. Ciliates (Paradileptus sp., Strobilidium sp. and Vorticella sp.) were the first herbivores which started to increase in April causing a twofold decline of phytoplankton biomass. The annual maximum of primary production (PP) in early May was probably caused by soluble reactive phosphorus (SRP), regenerated by herbivores, and stirred up from bottom sediments as a result of strong wind stress. This primary production peak provided substrate for further increase of bacterial biomass. The more abundant food supply supported the development of the second spring peak of herbivores (ciliates, rotifers, juvenile copepods) which was followed by the second modest “clear water phase” in late May. Silicon was depleted by the end of May causing a strong decrease in primary production of the diatom‐dominated community, whereas the biomass of the cyanophytes increased under the improved nutrient conditions. Some weeks later, inorganic N was depleted and the period of N limitation with the appearance of N‐fixing cyanophytes began. The ciliate collapse at the beginning of June coincided with the start of the cladoceran development and with the increase of other metazooplankton groups. This explains the further decrease of the biomass of phytoplankton and bacteria in spite of their high production. Beginning from late June, silicon appeared again and SRP started to occur periodically, while inorganic N remained close to zero until November. During this period, phytoplankton development relied to a great extent on the N‐fixation and N‐regeneration potential. The collapse of the ciliate community in September removed the top‐down control from bacteria and their biomass increased, while the development of cladocerans still suppressed phytoplankton biomass in spite of a quite high PP. In October phytoplankton biomass and chlorophyll a (Chla) increased, SRP was completely depleted by the middle of October reflecting a slow regeneration due to the declined activity of zooplankton in cold water. In November nitrates appeared again, and silicon reached the same level as in spring. The biomass of N‐fixing Aphanizomenon skujae decreased while Limnothrix redekei and L. planctonica were quite abundant together with diatoms.
Distribution of Brachionidae (Rotifera, Monogononta) in Inner Mongolian Waters
Authors: Rong Su , Segers H. , Dumont H. J.
Published: February 2007

Two‐hundred and fourty‐six freshwater and saline‐alkaline waters in Inner Mongolia, P.R. China were surveyed for Brachionidae. Twenty‐nine brachionid morphospecies (33 taxa) are recorded, four are new to China. Some data on their distribution, and comments on selected taxa are provided.Brachionus asplanchnoides(stat.nov.) is reinstated at the morphospecies level. We suggest that this taxon may be used in aquaculture, considering that, by its large size, it extends the size range of brackish‐water Rotifera potentially available as food for fish larvae.
The Influence of Hydraulic Stress on Microdistribution Patterns of Zoobenthos in a Sandstone Brook (Weidlingbach, Lower Austria)
Authors: Möbes‐Hansen B. , Waringer J. A.
Published: February 2007

In the Weidlingbach, a low‐order forest stream in the Wienerwald area near Vienna (Austria), hydraulic stress was measured at 112 locations from which benthic fauna (=33318 specimens of macro‐invertebrates) was collected between March and September 1995. For measuring hydraulic stress a set of FST hemispheres was used. The most abundant taxa studied (= 90.7% of the total) were Gammarus fossarum Koch (Amphipoda), Leuctra spp. (Plecoptera), the ephemeropterans Baetis rhodani (Pictet), B. vernus (Curtis), Habroleptoides confusa Sartori and Jacob, Ecdyonurus starmachi Sowa and the caddisfly Hydropsyche instabilis (Curtis).

Five mayfly, four stonefly and six caddisfly taxa significantly (p < 0.05) preferred the lotic subsection of the research area, whereas Ephemera danica Müller significantly (p < 0.001) preferred the lentic subsection.

In the species studied in detail, medians of their FST hemisphere ranges varied from 8 (e.g. Brachyptera risi (Morton)) to 2 (e.g. Paraleptophlebia submarginata (Stephens)).

A comparison of microdistribution patterns at low and high discharge revealed no significant shift in FST hemisphere numbers and, hence, in exposure to hydraulic stress in Hydropsyche instabilis and Rhyacophila fasciata Hagen; both species were most abundant in high stress areas, independent of discharge. On the other hand, most other species studied in detail exhibited a shift to lower hydraulic stress at high discharge, whereas Electrogena ujhelyii (Sowa) was evenly distributed (p > 0.05) over the whole range of hydraulic stress, independent of discharge.
Succession of Physical and Chemical Conditions and of Crustacean Communities in Some Small, Man Made Water Bodies
Authors: Maier Gerhard , Hössler Jürgen , Tessenow Uwe
Published: February 2007

We studied physical and chemical conditions and the crustacean communities in temporary ponds in a military area in South Germany. All ponds were formed by driving of tanks. They were turbid, without higher aquatic plants but contained a unique crustacean community with endangered species such as the anostracan Branchipus schaefferi, the copepods Cyclops furcifer and Metacyclops minutus and the cladocerans Daphnia obtusa, Moina brachiata and Macrothrix hirsuticornis. Branchipus was only present in ponds which dried out and where driving occurred. Ponds which did not dry out and where driving events were rare or did not take place were devoid of Branchipus. Physical and chemical conditions were similar in ponds with and without Branchipus. Day‐night fluctuations of temperature were up to 15 °C in summer. Conductivity was 200–300 μS cm−1, hardness ranged between 2 and 3.5 meq 1−1, alcalinity between 1 and 3 meq 1−1, pH between 7.5 and 9, dissolved phosphorus was <20 μg 1−1, concentration of nitrogen was <0.1 mg 1−1 and oxygen saturation was >60% in the ponds except one pond where concentrations of nutrients and conductivity were somewhat higher. When driving of tanks had been stopped the number and size of the ponds decreased and their character changed. Branchipus schaefferi and other endangered species disappeared and more but common, benthic species such as the cladoceran Chydorus sphaericus and the copepods Megacyclops viridis and Eucyclops serrulatus gained importance. Branchipus schaefferi is now close to extinction. Conductivity, hardness, alcalinity increased while pH decreased probably because algae were replaced by marsh plants. We conclude that driving of tanks raised clay particles, prevented the growth of higher aquatic vegetation and condensed the bottom sediments. All this was necessary to keep the ponds in an early stage of succession thus providing conditions necessary to maintain Branchipus.
A co‐clustering model involving α5β1 integrin for the biological effects of GPI‐anchored human carcinoembryonic antigen (CEA)
Authors: Camacho‐Leal Pilar , Zhai Alexander B. , Stanners Clifford P.
Published: February 2007

CEA functions as an intercellular adhesion molecule and is up‐regulated in a wide variety of human cancers, including colon, breast and lung. Its over‐expression inhibits cellular differentiation, blocks cell polarization, distorts tissue architecture, and inhibits anoikis of many different cell types. Here we report results concerning the molecular mechanism involved in these biological effects, where relatively rapid molecular changes not requiring alterations in gene expression were emphasized. Confocal microscopy experiments showed that antibody‐mediated clustering of a deletion mutant of CEA (ΔNCEA), normally incapable of self binding and clustering, led to the co‐localization of integrin α5β1 with patches of ΔNCEA on the cell surface. Activation of α5, as defined by an anti‐α5 mAb‐sensitive increase in cell adhesion to immobilized fibronectin, and an increased binding of soluble fibronectin to cells, was also observed. This was accompanied by the recruitment of integrin‐linked kinase (ILK), protein kinase B (PKB/Akt), and the mitogen‐activated protein kinase (MAPK) to membrane microdomains and the phosphorylation of Akt and MAPK. Inhibition of PI3‐K and ILK, but not MAPK, prevented the α5β1 integrin activation. Conversely, anti‐α5 antibody inhibited the PI3‐K‐mediated activation of Akt, implying the involvement of outside‐in and inside‐out signaling in integrin activation. Therefore we propose that CEA‐mediated signaling involves clustering of CEA and co‐clustering and activation of the α5β1 and associated specific signaling elements on the internal surfaces of membrane microdomains. These changes may represent a molecular mechanism for the biological effects of CEA. J. Cell. Physiol. 211: 791–802, 2007. © 2007 Wiley‐Liss, Inc.
Growth plate formation and development in alligator and mouse metapodials: evolutionary and functional implications
Authors: Reno Philip L. , Horton Walter E. , Elsey Ruth M. , Lovejoy C. Owen
Published: February 2007

Mammalian metapodials (metacarpals and metatarsals), unlike most long bones, form a single growth plate, and undergo longitudinal growth at only one end. The growth dynamics of non‐mammalian tetrapod metapodials have not been systematically examined in order to determine if unidirectional growth is unique to mammals. Here we compare murine metapodial ossification in growth stages that parallel those of embryonic, juvenile and subadult American alligators (Alligator mississippiensis). Safranin O staining was used for qualitative histology, and chondrocyte differentiation and proliferation were assessed via immunohistochemistry for type X collagen and proliferative cell nuclear antigen (PCNA). We establish that growth plates form at both ends of alligator metapodials and are maintained in the subadult. PCNA results show that alligators and mice share common patterns of chondrocyte proliferation during growth plate formation. In addition, while alligators and mice differ initially in the degree of organization and pace of chondrocyte differentiation, these parameters are largely similar in established growth plates. However, the replacement of cartilage by bone is highly irregular throughout growth in the alligator, in contrast to the more uniform process in the mouse. These results indicate that while alligators and mammals share common mechanisms of chondrocyte regulation, they differ substantially in their processes of ossification. Phylogenetic analysis indicates that the direct ossification of one epiphysis and reliance on a single growth plate is a derived character (synapomorphy) in therian mammals and likely indicates an adaptation for erect quadrupedal gait. J. Exp. Zool. (Mol. Dev. Evol.) 308B:283–296, 2007. © 2007 Wiley‐Liss, Inc.
First evidence of chitin as a component of the skeletal fibers of marine sponges. Part I. Verongidae (demospongia: Porifera)
Authors: Ehrlich Hermann , Maldonado Manuel , Spindler Klaus‐dieter , Eckert Carsten , Hanke Thomas , Born René , Goebel Caren , Simon Paul , Heinemann Sascha , Worch Hartmut
Published: February 2007

The Porifera (sponges) are often regarded as the oldest, extant metazoan phylum, also bearing the ancestral stage for most features occurring in higher animals. The absence of chitin in sponges, except for the wall of peculiar resistance bodies produced by a highly derived fresh‐water group, is puzzling, since it points out chitin to be an autapomorphy for a particular sponge family rather than the ancestral condition within the metazoan lineage. By investigating the internal proteinaceous (spongin) skeleton of two demosponges (Aplysina sp. and Verongula gigantea) using a wide array of techniques (Fourier transform infrared (FTIR), Raman, X‐ray, Calcofluor White Staining, Immunolabeling, and chitinase test), we show that chitin is a component of the outermost layer (cuticle) of the skeletal fibers of these demosponges. FTIR and Raman spectra, as well as X‐ray difractograms consistently revealed that sponge chitin is much closer to the α‐chitin known from other animals than to β‐chitin. These findings support the view that the occurrence of a chitin‐producing system is the ancestral condition in Metazoa, and that the α‐chitin is the primitive form in animals. J. Exp. Zool. (Mol. Dev. Evol.) 308B:347–356, 2007. © 2007 Wiley‐Liss, Inc.
Land use feedback on clear sky downward longwave radiation: a land use adapted model
Authors: Rizou Maria , Nnadi Fidelia
Published: February 2007

The existing models for downwelling longwave (LW) radiation employ different formulations for clear sky emissivity calculation. Even though both the temperature and water vapor affect emissivity, most models use either a lump humidity parameter or only one of these effects because of existing correlation between the two parameters. These parameters are further affected by heterogeneous land use patterns and temporal changes in atmospheric circulation patterns.

In this paper, a model considering the nonlinear temperature and water vapor pressure effects superpositioned in one equation to account for the net impact on clear sky emissivity is investigated. Furthermore, the developed model is enhanced to become robust and adaptable for different land uses. Ground radiometer and meteorological data applicable in the subtropical climate of Saint Johns River Water Management District (SJRWMD), FL, during the spring season are utilized for model development. The new model is tested against pyrgeometer data gathered above a crop in Bondville, IL, a rangeland in Ft. Peck, MT, and an urban setting in Deland, FL. When the new parameterization is validated using 24 h average downwelling LW flux, it yields a Nash‐Sutcliffe Efficiency (NSE) greater than 0.5, normalized Mean Bias Errors (MBE), and Root Mean Square Errors (RMSE) of less than 5% and 7%, respectively, with the latter being the smallest deviations with respect to existing formulations. Copyright © 2007 Royal Meteorological Society
Precise Synthesis of Dendrimer‐Like Star‐Branched Poly(methyl methacrylate)s with Different Branched Architectures up to Third‐Generation by Iterative Methodology
Authors: Watanabe Takumi , Hirao Akira
Published: February 2007

Four kinds of dendrimer‐like star‐branched poly(methyl methacrylate)s (PMMA)s with different branched architectures have been synthesized up to the third‐generation by developing the iterative divergent methodology which involves the following two elementary reactions: (a) a coupling reaction between α‐functionalized living anionic PMMA having two or four 3‐tert‐butyldimethylsilyloxymethylphenyl (SMP) groups and benzyl bromide (BnBr)‐multi‐functionalized core compound(s) or BnBr‐chain‐end‐multi‐functionalized PMMA, and (b) a transformation reaction of the introduced SMP group into BnBr function. The number of segments branched at the junction point could be readily controlled by adjusting BnBr reaction sites of the core and the polymer chain‐end in number. Characterization results on molecular weight, molecular weight distribution, and end‐group functionality revealed that the resulting branched polymers all herein synthesized were well‐defined in branched architecture and precisely controlled in chain length. In order to evaluate the solution properties of the third‐generation polymers, their viscosities and hydrodynamic radii were measured by viscometer and RALLS, respectively, and discussed.
A Novel Ferrocene‐DOPPV Conjugated Copolymer
Authors: Gonçalves Camila S. , Serbena José P. , Hümmelgen Ivo A. , Gruber Jonas
Published: February 2007

The synthesis of a conjugated copolymer, poly[(1,1′‐ferrocenylenevinylene)‐ co‐(2,5‐di‐n‐octyloxy)‐p‐phenylenevinylene] (PFV‐DOPPV) via McMurry coupling of 1,1′‐ferrocenedialdehyde and 2,5‐di‐n‐octyloxybenzene‐1,4‐dialdehyde is reported. PFV‐ DOPPV was fully characterized by 1H NMR, FTIR, FT‐Raman, UV‐VIS, cyclic voltammetry, size exclusion chromatography (SEC), inductively coupled plasma ‐ optical emission spectrometry (ICP‐OES), thermogravimetry (TG) and differential scanning calorimetry (DSC). The ionization potential, band‐gap energy, electron affinity, HOMO and LUMO levels could be estimated. Electrical measurements in a sandwich device exposed to magnetic fields revealed magnetoresistance.
Syntheses of Novel Polynorbornene Derivatives via Ring Opening Metathesis Polymerization
Authors: Liaw Der‐Jang , Wang Kun‐Li , Chen Wen‐Hsiang
Published: February 2007

Ring opening metathesis is an important class of controlled polymerization techniques. Synthesis of novel polynorbornene derivatives with functional groups designed for application in crosslikable and self assembling materials, and the polymerizations via ROMP and/or free radical polymerization are introduced. Novel monomers and/or macroinitiators for combination of two polymerization techniques are useful for controlling molecular architecture. The sequence of using controlled polymerization techniques affects the molecular structure and the properties of resulting polymers.
Advances in Film Blowing, Thermoforming, and Foaming by Using Long‐Chain Branched Polymers
Authors: Münstedt Helmut , Kurzbeck Stefan , Stange Jens
Published: February 2007

In many extrusion processes the uniformity of the geometry of the processed items is of great importance for their quality. It is shown how the uniformity of the wall thickness of a beaker thermoformed from polypropylene and of films blown from polyethylene can be improved by using long‐chain branched materials. Furthermore, a beneficial effect with respect to an increase of the expansion ratios of foams is observed for long‐chain branched polypropylenes. The common characteristics of all these three processing operations are pronounced biaxial elongational deformations. It is demonstrated that the occurrence of strain hardening is the key factor for an improvement of uniformity. As long‐chain branches are decisive for the amount of strain hardening it is shown how they contribute to a better quality in extrusion.
Diversity of Ion Path in Low Density Polyethylene Solid
Authors: Anada Yuichi
Published: February 2007

Electrical and Thermal properties of low density poly(ethylene) (LDPE) were observed by the measurement with the impedance analyzer and the differential scanning calorimetry (DSC) respectively. The frequency dispersion curves of the electric modulus were analyzed and investigated in comparison with the DSC data. The samples are annealed during various times. From the DSC data, it was found that the crystalline structure changes into more inhomogeneous structure on lamella thickness with increase in annealing time. On the other hand, the electrical experiment shows the plural process of ionic conduction on the frequency dispersion curves of the electric modulus. The number of processes is increased in the range from 1 to 3 with increase in the annealing time. In this manner, the correspondence between the result of the electrical experiment and the DSC strongly suggest that the ions included in LDPE move through the non‐crystalline parts near the crystallite surface because the inhomogeneity in lamella thickness produces the inhomogeneity in the parts near the surface of the lamella.
Electrochemical Modification of Graphite Electrodes with Poly(4‐aminophenol)
Authors: Vieira Sabrina Nunes , Ferreira Lucas Franco , Franco Diego Leoni , Afonso André Santiago , Gonçalves Rafael Ariza , Brito‐Madurro Ana Graci , Madurro João Marcos
Published: February 2007

It was observed the formation of polymeric films derived from 4‐aminophenol on the graphite electrode in aqueous medium (pH 0.5, 8.0 and 12.0). The electrochemical behavior of formed films was studied by voltammetry cyclic and impedance. These analyses indicate that the preparation in acid medium favors the charge transfer rate of the polymer. Polymers formed at pH 8.0 present higher coverage of the electrode surface and impedance increase. Scanning electron microscopy showed that the formed polymer present globular morphology.
Computer Simulations of Polyelectrolyte Stars Near Walls
Authors: Konieczny Martin , Likos Christos N.
Published: February 2007

We present results from monomer‐resolved, Molecular Dynamics computer simulations of multiarm, star‐shaped polyelectrolytes brought in the vicinity of planar, uncharged walls. We demonstrate that polyelectrolyte stars are very robust against planar confinement, in the sense that they maintain their key properties from the bulk, despite their strong deformation due to the wall: the chains remain stretched, the radius is insensitive to the wall and the number of trapped counterions is barely affected by the wall. We supplement our study with measurements of the star‐wall force and a corresponding analytic theory.
Optical Enhancing Properties in Layer‐by‐Layer Films of Dendrimer and Gold Nanoparticles
Authors: dos Santos David S. , Sanfelice Rafaela C. , Alvarez‐Puebla Ramon , Oliveira Osvaldo N. , Aroca Ricardo F.
Published: February 2007

Portable multilayer films containing gold nanoparticles embedded in a dendrimer matrix have been fabricated using the layer‐by‐layer (LbL) technique, characterized and tested for applications in surface‐enhanced Raman scattering (SERS). Film formation was monitored by microgravimetry measurements using a quartz crystal microbalance (QCM) and UV‐visible spectroscopy. The surface morphology was investigated with atomic force microscopy (AFM) measurements. SERS was recorded for 2‐Naphtalenethiol(NFT) cast onto the LbL film and the results show that the optical enhancing ability is a function of the number of bilayers. The analytes show an increase of SERS effect that follows the surface roughness, being stabilized after a certain number of bilayers are deposited.
Functional Textiles Based on Polymer Composites
Authors: Carfagna Cosimo , Persico Paola
Published: February 2007

Summary: Functional textiles provide ample evidence of the potential wealth of opportunities still to be realised in the textile industry. In this paper, intelligent‐wear garments with thermoregulating properties are prepared using phase change materials (PCMs) microcapsules and tested. At the same time, a series of nylon 6 nanocomposites with different filler/Jojoba Oil contents have been prepared with the purpose of obtain active fibers providing care, comfort and protection for the skin. Jojoba Oil delivery through polyamide matrix in conditions simulating current applications was studied by FT‐IR.
Application of Calorimetry Technique to Estimate Conversion of Polymerization Reactions in a Standard Lab‐Scale Reactor
Authors: Esposito M. , Sayer C. , Machad R. A. F. , Araújo P. H. H.
Published: February 2007

Reaction calorimetry is a very useful tool for monitoring exothermic polymerization reactions as it uses the measurement of the liberated energy to calculate the reaction rates. Despite the estimation of conversion for homopolymerizations being well established for commercial calorimetry reactors or lab‐scale reactors specially constructed to operate as calorimetry reactors, it is still a challenge to use calorimetry to estimate conversion in standard lab‐scale reactors. In the present work, a standard lab‐scale jacketed stainless steel tank reactor with an internal volume of 5 liters was instrumented to operate as a calorimetric reactor. Water was used as the heating/cooling fluid and its flow rate was kept constant. The isothermal calorimetry and isoperibolic calorimetry were used to determine the conversion of batch vinyl acetate emulsion polymerization. Both results were compared and showed that, even at a relatively high residence time of the cooling fluid in the jacket (∼18 s) and significant heat loss, estimated conversions obtained by the measurements of reactor and jacket temperatures and by the mass and energy balances presented a good agreement with gravimetric data.
Nitroxide‐Substituted Polyether as a New Material for Batteries
Authors: Suga Takeo , Yoshimura Kentaro , Nishide Hiroyuki
Published: February 2007

Nitroxide‐substituted polyether was synthesized as a cathode‐active material for a secondary battery. Anionic ring‐opening polymerization of a TEMPO‐bearing glycidyl ether was carried out under bulk conditions to yield the corresponding polymer with the molecular weight of >104. The obtained polymer was insoluble, but slightly swollen in the electrolyte solution (ethylene carbonate/propylene carbonate). The test cell fabricated with a carbon composite cathode of this radical polymer displayed a plateau voltage at 3.5 V vs. Li/Li+. The cell performance was maintained even with a higher amount of the radical polymer loaded in the composite electrode, which could be ascribed to the flexible and rubbery polyether backbone and its higher compatibility with the electrolyte solution.
Synthesis and Characterization of Sulfonated‐ Fluorinated, Hydrophilic‐Hydrophobic Multiblock Copolymers for Proton Exchange Membranes
Authors: Yu Xiang , Roy Abhishek , Dunn Stuart , Yang Juan , McGrath James E.
Published: February 2007

Nanophase separated ionic‐hydrophobic block copolymers may be more suitable as proton exchange membranes than random copolymers. A series of multiblock copolymers, composed of alternating segments of fully disulfonated poly(arylene ether sulfone) and highly fluorinated poly(arylene ether sulfone), were synthesized from hydrophilic and hydrophobic telechelic oligomers having a variation of molecular weights. The high reactivity of the fluorinated oligomers made unnecessary the use of high reaction temperatures, and thus the coupling reactions may be free of ether‐ether interchange side reactions. The copolymers were characterized with regard to proton conductivity, water uptake and self‐diffusion coefficient of water, and the results were compared to those of Nafion and a partially disulfonated BPSH‐35 random copolymer.
Nanoscale Heterogeneities in Nematic Azobenzene Polymethacrylates for Optical Nanowriting
Authors: Galli Giancarlo , Szanka Istvan , Andreozzi Laura , Autiero Ciro , Faetti Massimo , Giordano Marco , Zulli Fabio
Published: February 2007

ESR studies of the rotational dynamics of the cholestane spin probe dissolved in nematic azobenzene polymethacrylates from above TNI to below Tg are presented. Different dynamic regimes were recognized, in which the molecular sites or distributions of molecular sites were populated depending on the structure of the polymers and their thermal histories. We highlight the significance of such spatial‐temporal nanoscale heterogeneities in view of possible application of the azobenzene polymers in erasable optical nanowriting.
Nanocomposite Membranes Based on Sulfonated Poly(etheretherketone) Structured with Modified Silica for Direct Ethanol Fuel Cell
Authors: Tan Ai Ren , de Carvalho Luisa Magno , de Ramos Filho Florêncio Gomes , de Souza Gomes Ailton
Published: February 2007

Polymer blend of sulfonated poly(oxy‐1,4phenyleneoxy‐1,4phenylenecarbonyl‐1,4phenylene) (SPEEK) and poly(ether sulfone) (PES) was compounded with commercial and synthesized silica. PES phase had important role to improve the stability and to reduce permeability of sulfonated matrix to alcohol solution, but it also reduced the proton conductivity of membrane. The addition of synthesized silica, which had heteropolyacid phosphotungstic acid (HPW) occluded inside the silica matrix (SiO2 · HPW) was evaluated to improve the conductivity.
Antibacterial Activity of Chitosan Solutions for Wound Dressing
Authors: Campos Maria , Cordi Lívia , Durán Nelson , Mei Lucia
Published: February 2007

Chitosan has found wide application in the biomedical field due to its interesting biological properties that include: biocompatibility, biodegradability, hemostatic activity and bacteriostatic effect. In this present study, antibacterial activity of chitosan solutions for wound dressing were investigated against Staphylococcus aureus (isolated from an activated sludge) and Escherichia coli (ATCC 25922) that are potential wound pathogens. Moreover, the effects of plasticizer addition and chitosan concentration on antibacterial activity of chitosan solutions were also evaluated. According to the antibacterial activity study, chitosan solutions, plasticized or not, showed inhibitory activity against Escherichia coli. However, they did not inhibit Staphylococcus aureus growth, possibly because this bacterium strain would become resistant due to mutations caused by industrial effluent exposure.
Functional Properties of Corn Starch Treated with Corona Electrical Discharges
Authors: Nemtanu Monica R. , Minea Radu
Published: February 2007

Starch is one of the biopolymers widely used as a raw material in various industries, its usage being based on its functional properties. Corona electrical discharges treatment is one of the newest methods among the physical methods to modify starch. Thus, the paper deals with the behavior study of some functional properties of corn starch exposed to corona electrical discharges. The apparent viscosity of corn starch increased while the solubility, gel consistency and clarity of pastes have been reduced with the increase of exposure time.
A Preliminary Study for the Use of Natural Fibers as Reinforcement in Starch‐Gluten‐Glycerol Matrix
Authors: Corradini Elisângela , de Morais Luís C. , de F. Rosa Morsyleide , Mazzetto Selma E. , Mattoso Luiz H. C. , Agnelli José A. M.
Published: February 2007

Mercerized and nonmercerized coconut, jute and sisal fibers were combined with a matrix of gluten/starch/glycerol to produce composite materials. All nonmercerized fibers improved the mechanical properties of the composites. After mercerization of the fibers, the composite reinforced with sisal fibers exhibited lower values of Young's modulus and ultimate tensile strength than composite with nonmercerized sisal fiber, whereas these properties were improved in the composites reinforced with mercerized coconut and jute fibers.
Synthesis of PEO‐Based Materials for Biomedical Applications
Authors: Kim Jungahn , Choi Song‐yee , Kim Kyung Min , Lee Cheol Han , Park Hyeong Soo , Hwang Seung Sang , Hong Soon Man , Kwak Soonjong , Yoo Hyun‐Oh
Published: February 2007

We have successfully carried out living anionic ring‐opening polymerization of ethylene oxide in the mixture of benzene/dimethyl sulfoxide (DMSO) using authentic n‐butyllithium with potassium tert‐butoxide as the initiating system. The resulting poly(ethylene oxide) (PEO) used for biomedical applications could be readily modified by chain‐end functionalizations. It was possible to control the molecular weight of PEO as well as to achieve quantitative chain‐end functionalizations of PEO.
Understanding the Processing of Thermoplastic Starch
Authors: Stepto R.F.T.
Published: February 2007

The thermoplastics processing of native starch in the presence of water is a recent development with very wide possible applications. Eventually, oil‐based polymer materials have to be replaced in many applications by sustainable, inexpensive, natural materials from renewable resources. The present contribution focuses on the injection moulding of starch. The bases of the processing and the thermal and molecular changes occurring are described. In addition, the rheological behaviour of starch‐water melts during processing is analysed quantitatively to give apparent melt viscosities. The dimensional, thermal and mechanical properties of moulded thermoplastic starch polymer (TSP) materials and the products presently being produced from them are discussed.
High Energy Containing Fractions from Plastic Wastes by Their Chemical Recycling
Authors: Miskolczi Norbert , Bartha Laszlo , Angyal Andras
Published: February 2007

Different conventional fractions of oil industry were produced by the cracking of real plastic wastes under mild conditions in a horizontal tube reactor. The influence of the raw material (HDPE, PP, HDPE/PS and HDPE/PP/PS/PA/PVC) on the characteristic of the cracked products was studied. It was found that waste polymers could be converted into valuable lighter fractions (gas, naphtha, middle distillates or light oil) with yields of 30–60% depending on the applied cracking parameters. The gas and liquid products had significant content of unsaturated hydrocarbons, mainly α‐olefins, but their types (vinyl or vinilydene) were considerably affected by the composition of raw materials. Lighter naphtha‐like fractions had high octane numbers (83 < RON < 94), while high cetane numbers (>68) in case of middle distillates. Products from suitable raw materials had very low sulphur, nitrogen and hetroatom content (<10 ppm) or products are sulphur and nitrogen free. Due to the high energy content of products there is a good chance of energetic utilization, but the possibility of their application is mainly depending on the composition of feed plastics.
SERCA pump isoforms: Their role in calcium transport and disease
Authors: Periasamy Muthu , Kalyanasundaram Anuradha
Published: February 2007

The sarcoendoplasmic reticulum (SR) calcium transport ATPase (SERCA) is a pump that transports calcium ions from the cytoplasm into the SR. It is present in both animal and plant cells, although knowledge of SERCA in the latter is scant. The pump shares the catalytic properties of ion‐motive ATPases of the P‐type family, but has distinctive regulation properties. The SERCA pump is encoded by a family of three genes, SERCA1, 2, and 3, that are highly conserved but localized on different chromosomes. The SERCA isoform diversity is dramatically enhanced by alternative splicing of the transcripts, occurring mainly at the COOH‐terminal. At present, more than 10 different SERCA isoforms have been detected at the protein level. These isoforms exhibit both tissue and developmental specificity, suggesting that they contribute to unique physiological properties of the tissue in which they are expressed. The function of the SERCA pump is modulated by the endogenous molecules phospholamban (PLB) and sarcolipin (SLN), expressed in cardiac and skeletal muscles. The mechanism of action of PLB on SERCA is well characterized, whereas that of SLN is only beginning to be understood. Because the SERCA pump plays a major role in muscle contraction, a number of investigations have focused on understanding its role in cardiac and skeletal muscle disease. These studies document that SERCA pump expression and activity are decreased in aging and in a variety of pathophysiological conditions including heart failure. Recently, SERCA pump gene transfer was shown to be effective in restoring contractile function in failing heart muscle, thus emphasizing its importance in muscle physiology and its potential use as a therapeutic agent. Muscle Nerve, 2007
Numerical studies of shear banding in interface shear tests using a new strain calculation method
Authors: Wang Jianfeng , Gutierrez Marte S. , Dove Joseph E.
Published: February 2007

Strain localization is closely associated with the stress–strain behaviour of an interphase system subject to quasi‐static direct interface shear, especially after peak stress state is reached. This behaviour is important because it is closely related to deformations experienced by geotechnical composite structures. This paper presents a study using two‐dimensional discrete element method (DEM) simulations on the strain localization of an idealized interphase system composed of densely packed spherical particles in contact with rough manufactured surfaces. The manufactured surface is made up of regular or irregular triangular asperities with varying slopes. A new simple method of strain calculation is used in this study to generate strain field inside a simulated direct interface shear box. This method accounts for particle rotation and captures strain localization features at high resolution. Results show that strain localization begins with the onset of non‐linear stress–strain behaviour. A distinct but discontinuous shear band emerges above the rough surface just before the peak stress state, which becomes more expansive and coherent with post‐peak strain softening. It is found that the shear bands developed by surfaces with smaller roughness are much thinner than those developed by surfaces with greater roughness. The maximum thickness of the intense shear zone is observed to be about 8–10 median particle diameters. The shear band orientations, which are mainly dominated by the rough boundary surface, are parallel with the zero extension direction, which are horizontally oriented. Published in 2007 by John Wiley & Sons, Ltd.
Triaxial behaviour of transversely isotropic materials: application to sedimentary rocks
Authors: Rouabhi A. , Tijani M. , Rejeb A.
Published: February 2007

Failure and long‐term behaviour of oriented solids are studied. Transversely isotropic materials are considered and a mathematical formulation that respect the material symmetry is developed and applied to model the triaxial behaviour of sedimentary rocks. Two failure criteria and a viscoplastic constitutive model that describe, respectively, triaxial failure and triaxial creep tests are presented and discussed. The application of the developed models to describe the mechanical behaviour of Tournemire shale shows that theoretical predictions are in good agreement with the experimental data. In the present paper, the developed approach is applied to sedimentary rock materials, nevertheless, it can be generalized to any material that exhibits transverse isotropy. Copyright © 2007 John Wiley & Sons, Ltd.
Different attitudes of Chinese patients and their families toward truth telling of different stages of cancer
Authors: Jiang Yu , Liu Chang , Li Jun‐Ying , Huang Mei‐Juan , Yao Wen‐Xiu , Zhang Ru , Yao Bing , Du Xiao‐Bo , Chen Jing , Xie Ke , Zhao Xia , Wei Yu‐Quan
Published: February 2007

Objective: Cancer patients and their families differed in their attitude toward truth telling. The objective is to investigate different attitudes of Chinese patients or families toward whether and how to disclose diagnosis to patients with different stages of cancer and to examine the difference between the two groups.

Methods: A questionnaire was delivered to 1023 participants.

Results: Three hundred and eighty‐two patients and 482 families completed the questionnaire. Cancer patients were more likely than families to believe that patient should be informed of the diagnosis (early‐stage, 90.8 vs 69.9%, P<0.001; terminal stage, 60.5 vs 34.4%, P<0.001), and that doctor‐in‐charge was the appropriate person to disclose the diagnosis. Most participants thought that patient should be disclosed immediately after the diagnosis. Nearly half of participants reported that patient should be disclosed in a quiet and undisturbed room. When the hypothetic diagnosis changed from early‐stage cancer to terminal illness, the number of participants, who wanted patient to know the diagnosis, decreased significantly.

Conclusion: Our findings indicated that Chinese cancer patients and their families differed in their attitude toward truth telling and the attitudes toward such a disclosure were influenced by disease stage. Physicians should realize this phenomenon and pay more attention to the skills of how to disclose the cancer diagnosis. Copyright © 2007 John Wiley & Sons, Ltd.
Analycys: A database for conservation and conformation of disulphide bonds in homologous protein domains
Authors: Thangudu Ratna R. , Sharma Priyanka , Srinivasan N. , Offmann Bernard
Published: February 2007

Disulphide bonds in proteins are known to play diverse roles ranging from folding to structure to function. Thorough knowledge of the conservation status and structural state of the disulphide bonds will help in understanding of the differences in homologous proteins. Here we present a database for the analysis of conservation and conformation of disulphide bonds in SCOP structural families. This database has a wide range of applications including mapping of disulphide bond mutation patterns, identification of disulphide bonds important for folding and stabilization, modeling of protein tertiary structures and in protein engineering. The database can be accessed at: http://bioinformatics.univ‐reunion.fr/analycys/. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Walking through the protein sequence space: Towards new generation of the homology modeling
Authors: Frenkel Zakharia M. , Trifonov Edward N.
Published: February 2007

A new method is proposed to reveal apparent evolutionary relationships between protein fragments with similar 3D structures by finding “intermediate” sequences in the proteomic database. Instead of looking for homologies and intermediates for a whole protein domain, we build a chain of intermediate short sequences, which allows one to link similar structural modules of proteins belonging to the same or different families. Several such chains of intermediates can be combined into an evolutionary tree of structural protein modules. All calculations were made for protein fragments of 20 aa residues. Three evolutionary trees for different module structures are described. The aim of the paper is to introduce the new method and to demonstrate its potential for protein structural predictions. The approach also opens new perspectives for protein evolution studies. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Analysis of power enhancement of terahertz waves in periodically inverted GaP pumped at 1.55 mm
Authors: Tomita I. , Suzuki H. , Rungsawang R. , Ueno Y. , Ajito K.
Published: February 2007

We have generated terahertz (THz) waves by difference frequency generation (DFG) with a 1.55 μm pump laser. 1.55 μm pump beams were effectively converted to 1 THz waves through a periodically χ(2)‐inverted GaP stack fabricated by direct wafer bonding. The output efficiency was an order of magnitude larger than that of typical χ(2) materials such as lithium niobate employing a similar DFG method. To investigate the increase in output power due to quasi‐phase matching including optical losses, we measured its dependence on stack length. From the measured data, we analyze the conditions for effective power enhancement and show that it takes place if the pump‐beam loss, α, is much smaller than that of the THz waves, α3 (or the pump‐beam attenuation length, 1/α, is much longer than that of the THz waves, 1/α3), which is achieved by improving the bonding quality of the stack. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The role of vacancies in the mobility of dislocations and grain boundaries in magnesium
Authors: Lambri O. A. , Massot M. , Riehemann W. , Lucioni E. J. , Plazaola F. , García J. A.
Published: February 2007

Vacancy flux or supersaturation enhances grain‐boundary mobility, but experimental evidence is not large and in many cases the role of vacancies is only inferred indirectly. We will show effectively in the present work the importance of the vacancy role in grain‐boundary mobility in commercial pure and high‐purity magnesium using mechanical spectroscopy, electrical resistivity and positron annihilation spectroscopy. It has been found that the mobility decrease of grain boundaries and dislocations is related to vacancy concentration reduction attained after the homogenisation treatment. Indeed, the largest vacancy concentration reduction is observed between 420 and 500 K. Unlocking grain boundaries and dislocations requires new vacancies, generated at temperatures above 500 K. In addition, a new damping peak related to vacancies was discovered at 490 K for an oscillating frequency of 1 Hz. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface melting of close‐packed Mg(0001), compared with Al(111)
Authors: Yang Jianyu , Hu Wangyu , Xiao Shifang , Yi Guojun
Published: February 2007

Using molecular dynamics simulations and an analytic embedded‐atom method, a comparative study of the surface anharmonicity for the close‐packed surface of Mg(0001) and Al(111) is presented in the temperature range from 0 K to their melting temperatures. The temperature dependences of the surface phonon frequencies, the mean square vibrational amplitudes of surface atoms and the layer structure factor are calculated. The calculated results are in good agreement with the available experimental data. Although with the same atomic arrangement for the top layer, Al(111) preserves its crystalline order in the temperature range considered, and Mg(0001) exhibits surface melting. The possible mechanism for the different melting behaviors of the two surfaces is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spontaneous emission enhancement in quantum cascade structures in the TeraHertz domain
Authors: Todorov Yanko , Sagnes Isabelle , Gennser Ulf , Coron Nöel , Minot Christophe , Abram Izo
Published: February 2007

We have fabricated and studied MOCVD grown quantum cascade devices operating in the far infrared frequency range (at about 4 THz). The devices are processed into double metal waveguides, in order to investigate the Purcell effect on the spontaneous emission rate due to the electromagnetic field confinement. Intersubband electroluminescence is outcoupled by a metallic grating, which also serves as the cavity upper mirror. The power collected per quantum cascade period increases when the device thickness is reduced, indicating a Purcell spontaneous emission enhancement factor up to about 50. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)