bluuebunny/crossref_metadata_2025_split huggingface dataset:
PLLA Based Composites with α‐Tricalcium Phosphate and a PLLA‐PEO Diblock Copolymer
Authors: Bigi Adriana , Boanini Elisa , Maglio Giovanni , Malinconico Mario , Palumbo Rosario , Scafati Santolo Taglialatela 
Published: March 2006

AbstractHybrid composites consisting of poly(L‐lactide), PLLA, or blends of PLLA with a PLLA‐poly(ethylene oxide) diblock copolymer (15–30 wt%), COP, as a biodegradable polymeric matrix and of bioactive α‐tricalcium phosphate, α‐TCP, microparticles as dispersed phase (25–40 wt‐%) were prepared by melt extrusion and their thermal, mechanical and degradation behaviour was investigated. SEM analysis of surfaces broken in liquid N2 showed a good dispersion of α‐TCP in the polymer matrix. A lowering of the glass transition temperature of the polymer matrix and enhanced crystallization rates of PLLA, both from the melt and from the glassy state, were observed in the presence of COP. Ternary PLLA/COP/α‐TCP composites containing about 10 wt‐% of COP and 25–40 wt‐% of α‐TCP showed improved compressive strength and deformation at yield as compared to pure PLLA. Degradation experiments revealed that in simulated body fluid the presence of α‐TCP particles promoted the formation of inorganic deposits of a poor crystalline apatitic phase on composite surfaces as compact sferoids.
A Novel Route to Graft‐Copolymers with Tailored Structures for the Compatibilization of Polymeric Blend
Authors: Caporaso Lucia , Iudici Nicola , Oliva Leone 
Published: March 2006

AbstractA new method to synthesize graft‐copolymers based on isotactic polypropylene (iPP) with tailored structure has been developed. The synthesis is a two‐step process: synthesis of P‐co‐(p‐MS‐E) copolymers, by using ansa‐metallocene catalysts, and metallation of p‐Me groups followed by living anionic polymerisation for the graft growth. This method turn out to be versatile because, by changing experimental conditions, in the first step backbones with a tuned number of the graft growth sites and polypropylene lengths can be obtained, whereas in the second step, graft chains of different types and lengths can be synthesized. The particular ability of these copolymers to compatibilize polymeric blends was evaluated analyzing the morphology of the products copolymers/blends by using a scanning electron microscopy (SEM).
Synthesis of Energetic Polyethers from Halogenated Precursors
Authors: Barbieri Ugo , Polacco Giovanni , Massimi Roberto 
Published: March 2006

AbstractIn the solid rocket propellant formulations an important component is the polymeric binder. Actually, the most used binder is hydroxyl‐terminated polybutadiene. However, the research is oriented toward the use of energetic polymers which, in addition to the binder function, should improve the propulsion capability of the propellant. In this respect, good candidates are oxetanic polyethers with azidic functionalities in their side chains. Considering the explosive character of such materials, their synthesis must be designed with attention to the safety of the process. In this note, the preparation of azidic copolymers is described and different synthetic strategies are discussed and compared.
Polypropylene‐POSS Nanocomposites: Morphology and Crystallization Behaviour
Authors: Pracella Mariano , Chionna Donatella , Fina Alberto , Tabuani Daniela , Frache Alberto , Camino Giovanni 
Published: March 2006

AbstractNanocomposites of isotactic polypropylene (PP) with polyhedral oligomeric silsesquioxanes (POSS) [RSiO1,5]8 having different alkyl substituents (R = methyl, isobutyl, isooctyl) were obtained by melt blending and analysed with electron microscopy, optical microscopy and DSC calorimetry. The influence of POSS structure on the morphological characteristics, the crystallization and melting behaviour of PP/POSS composites was investigated with varying the filler amount. The crystallization kinetics of the composites from the melt, examined both in isothermal and non‐isothermal conditions, demonstrated that the nucleation activity of the examined POSS can be related to the length of alkyl substituents which, depending on the loading amount, affect the filler dispersion in the PP matrix and the growth of polymer crystals.
Novel Thiophenic Copolymer as a Multi‐Purpose Macromolecular Intermediate
Authors: Paganin Luisa , Costa‐Bizzarri Paolo , Lanzi Massimiliano , Cesari Gaia , Bertinelli Franco , Cagnoli Rita , Mucci Adele 
Published: March 2006

AbstractThe preparation of a new thiophenic dimer partially derivatized with a bromohexylic chain is described. Its polymerization under mild oxidative conditions leads to a polythiophene with a degree of functionalization of 50% and highly soluble in organic solvents. The product has been fully characterized by FT‐IR, 1H and 13C NMR using one and two‐dimensional techniques as well as by SEC and thermal analysis. Solvatochromic effects of the new polymer have been investigated in different mixtures, underlining its self‐assembling capability even in solvated states.
Ligands Tethering to Biocompatible Ultrasound Active Polymeric Microbubbles Surface
Authors: Cavalieri Francesca , Hamassi Ali El , Chiessi Ester , Paradossi Gaio , Villa Raffaella , Zaffaroni Nadia 
Published: March 2006

AbstractUltrasound imaging, also known as echography, is a widespread diagnostic tool in medicine. Handiness and versatility are established assets of this non‐invasive imaging technique. Echogenic devices enhance the sensitivity of this method and formulations of novel systems is a growing field in biomedical research. In this contribution we describe the synthesis, the mesoscopic characterization, and the functionalization of microbubbles based on telechelic poly (vinyl alcohol) for a next‐generation ultrasound imaging multifunctional device suitable for diagnosis as well as for therapeutic purposes.
Oriented Nanoporous Host δ Phases of Syndiotactic Polystyrene as a Tool for Spectroscopic Investigation of Guest Molecules
Authors: Albunia Alexandra R. , Grassi Alfonso , Milano Giuseppe , Rizzo Paola , Venditto Vincenzo , Musto Pellegrino , Guerra Gaetano 
Published: March 2006

AbstractAn efficient method to align low‐molecular‐mass molecules by enclosing them as isolated guests of the nanoporous host δ phase of syndiotactic polystyrene oriented films, is presented. This new method is compared with the classic method consisting in the absorption of low‐ molecular‐mass molecules as a solute of amorphous phases of highly oriented semicrystalline polymeric films. It is shown that this new molecular alignment method provides a powerful tool to study in detail several features (spectroscopic properties, molecular motions) of relevant molecules, by separating with unprecedented selectivity their anisotropic spectral responses. The reported results refer to infrared and solid‐state‐2H‐NMR spectra.
Structure and Properties of a Polypropylene Containing Random Ethylene Units Modified with a Hydrogenated Hydrocarbon Resin
Authors: Cimmino Sossio , Duraccio Donatella , Silvestre Clara 
Published: March 2006

AbstractThe system formed by a polypropylene containing random low ethylene content (EP copolymer) of and a hydrogenated hydrocarbon resin (HR) is investigated in order to study the influence of resin (up to 20% in wt) on properties of blends and derived films. The random EP copolymer used is MoplenEP2C37F and the resin is MBG273 of Hercules Chemical Co. DSC and DMTA analyses of the blends show increase of Tg with resin content indicating that the two components are compatible in the amorphous phase. WAXD spectra show that MBG273 influences slightly the crystalline structure of EP copolymer. In fact the diffractograms of the EP copolymer and 95/5 blend present, beside the predominant peak of α form, also a small span denoting presence of γ form; this span is not detectable on spectra of 90/10 and 80/20 samples. The crystallization during the cooling is found to be only lightly delayed by the HR: in fact, only 4 degrees is the difference between the Tc values of EP copolymer and 80/20 blend. Stress‐strain test performed at room temperature show that MBG273 induces increase of Young's modulus and small decrease of elongation at break as function of resin content. An important effect is on the water vapour permeability, which decreases with resin content. The permeability and tensile properties are related to the increase of the glass transition with the addition of MBG273 that transforms gradually the amorphous of the material from rubbery to glassy. The results reported in this work indicate that an addition of 5–10% of MBG273 changes favourably properties, as Young' modulus and water vapour permeability, of an EP copolymer designed for the production of films for packaging application.
rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]ZrCl2/MAO in the Copolymerization of Olefins and Dienes
Authors: Pragliola Stefania , Costabile Chiara , Napoli Mariagrazia , Guerra Gaetano , Longo Pasquale 
Published: March 2006

AbstractOlefin‐diene copolymerizations in the presence of C2 symmetric zirconocene rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]ZrCl2/MAO catalytic system have been reported and rationalized by experimental and molecular modeling studies. Ethene gives 1,2‐cyclopropane and 1,2‐cyclopentane, 1,3‐cyclobutane, and 1,3‐cyclopentane units in copolymerization with 1,3‐butadiene, 1,4‐pentadiene, and 1,5‐hexadiene, respectively. Propene‐1,3‐butadiene copolymerizations lead to 1,2 and 1,4 butadiene units and to a low amount of 1,2‐cyclopropane units.
On the Bulk Properties of a Poly(Bicycloacrylate) Carrying Semifluorinated Side Groups
Authors: Martinelli Elisa , Domenici Valentina , Ragnoli Marina , Moszner Norbert , Galli Giancarlo 
Published: March 2006

AbstractWe prepared a novel fluorinated polymer from a bicycloacrylate monomer, (1H,1H,2H,2H)‐perfluorododecyl 2‐(bicyclo[3.1.0]hex‐1‐yl)acrylate, by radical ring opening polymerization. The bulk properties of the polymer were investigated by thermal analysis and X‐ray diffraction, which proved the existence of a smectic mesophase up to the isotropization temperature of 74 °C. Furthermore, a solid state NMR study was started to characterize domains with different mobility mainly by 13C cross‐polarization magic angle spinning and T2 selective experiments. We found that the polymer is a homogeneous sample with the presence of dynamic motions in the kHz regime below the glass transition temperature.
Nanocomposite Fibers for Cosmetotextile Applications
Authors: Persico Paola , Carfagna Cosimo , Musto Pellegrino 
Published: March 2006

AbstractIn this work, a series of nylon 6 nanocomposites with different nanoclay/jojoba oil contents have been prepared by direct melt compounding. Nanocomposite morphologies were characterized by means of WAXS analysis. Thermal and mechanical fibers properties were studied as well. The kinetic desorption of the cosmetic oil through the polymer matrix was evaluated by FT‐IR microscopy. It was found that the state of the clay particles affected the thermal behaviour and the tensile mechanical properties of each polymer/clay hybrid. On the other hand, the release of the cosmetic oil, tested by FT‐IR microscopy, is a good perspective for the application of polyamide 6 nanocomposite fibers as textiles in cosmetic field.
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

AbstractIn 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

AbstractTwo 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

AbstractIn 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

AbstractThe 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

AbstractSilica 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

AbstractVinyl 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

AbstractThe 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

AbstractHemidystonia 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

AbstractThis 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

Abstract2,3,7,8‐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.