bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractThe 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

AbstractFour 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

AbstractThe 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

AbstractRing 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

AbstractIn 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

AbstractElectrical 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

AbstractIt 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

AbstractWe 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

AbstractPortable 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

AbstractSummary: 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

AbstractReaction 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

AbstractNitroxide‐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

AbstractNanophase 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

AbstractESR 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

AbstractPolymer 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

AbstractChitosan 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

AbstractStarch 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

AbstractMercerized 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

AbstractWe 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

AbstractThe 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

AbstractDifferent 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

AbstractThe 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