bluuebunny/crossref_metadata_2025_split huggingface dataset:
The anatomy of tubercles: A corrosion study in a fresh water estuary
Authors: Ray R. I. , Lee J. S. , Little B. J. , Gerke T. L. 
Published: December 2010

AbstractThe structure and mineralogy of corrosion products formed on carbon steel coupons exposed in Duluth Superior Harbor (DSH, USA), were investigated and compared with corrosion products on similar substrata from other locations. Corrosion products in DSH form within a few months each year and are removed by ice scour and reform. The corrosion products formed in DSH are tubercles with an outer surface, an inner shell of magnetite, and a core of iron(III) oxyhydroxides, goethite, and lepidocrocite, in association with stalks produced by bacteria. In general, the tubercles formed in DSH are similar in morphology and mineralogy to corrosion products described for carbon steel and cast iron exposed to treated waters in decades‐old drinking water and cooling water systems. DSH tubercles are unique in several structural details. DSH tubercles increase areal coverage of the substratum by consolidation of tubercles. Furthermore, the core material extends into the pit and is an exact replica of the pit profile.
A Unique Meta‐Form Structure in the Stereocomplex of Poly(D‐lactic acid) with Low‐Molecular‐Weight Poly(L‐lactic acid)
Authors: Chang Ling , Woo Eamor M. 
Published: December 2010

AbstractThe crystalline structure and crystallization behavior of PLLA crystals in a 1:1 w/w mixture of low‐MW PLLA with high‐MW PDLA were analyzed using WAXD, DSC, and SAXS. Under cold crystallization, homopolymeric PLLA, appearing as a meta crystal, was discovered in the PDLA/LMW‐PLLA blend. The meta‐ and α′ crystal forms of PLLA were found to form on crystallization at a Tcc of 85–95 °C and the α crystal PLLA formed at 100 ≤ Tcc < 120 °C. The meta‐crystal PLLA may be incorporated in the stereocomplexed PDLA/LMW‐PLLA lamellar region. During heating, the meta‐crystal PLLA first partially melted and then repacked directly into the α crystal PLLA without going through the less‐stable α′ form. magnified image
Improved Synthesis Strategy of Poly(amidoamine)s for Biomedical Applications: Catalysis by “Green” Biocompatible Earth Alkaline Metal Salts
Authors: Zintchenko Arkadi , van der Aa Leonardus J. , Engbersen Johan F. J. 
Published: December 2010

AbstractPoly(amidoamine)s (PAAs) have received significant attention due to their good biocompatibility and fast biodegradation profile which gives these polymers high potential in biomedical applications. Conventional synthesis of PAAs via aza‐type Michael addition reaction of primary amines to bis‐acrylamides often proceeds slowly and takes several days, which does not allow fast and extensive screening of PAA libraries for their bioactivity. Current investigation was dedicated to the development of catalytic synthesis procedures in order to decrease the polymerization times. The salts of several transition metals, as well as earth alkali metals were studied for their catalytic activity in the polymerization reaction. It was found that the salts of earth alkali metals showed the highest potential in the catalysis of polymerization, whereas the salts of transition metals showed either no effect or even resulted in slowing down the reaction. In particular, the addition of CaCl2 to the reaction mixtures resulted in remarkable increase of the reaction rate as compared to the system without catalyst. PAAs synthesized by the conventional procedure and those obtained by using CaCl2 as a catalyst showed no difference in physico‐chemical properties as well as in biological activity. The novel synthetic method for PAAs, using catalysts based on earth alkali metals, represents an attractive alternative to currently applied methods. Characteristics of earth alkali metals such as low toxicity and good biocompatibility make them especially useful in the preparation of these polymers for biomedical applications. magnified image
Precise Synthesis of Molecularly Defined Oligomers and Polymers by Orthogonal Iterative Divergent/Convergent Approaches
Authors: Binauld Sandra , Damiron Denis , Connal Luke A. , Hawker Craig J. , Drockenmuller Eric 
Published: December 2010

AbstractThe synthesis of perfectly defined (macro)molecules has been a constant challenge for polymer and organic chemists. This paper highlights the main applications of the iterative divergent/convergent approach for the synthesis of discrete mass oligomers and polymers. We will discuss the orthogonal deprotection and coupling strategies involved in this powerful strategy where chain length doubles at each iteration and which has been applied to the synthesis of conjugated rigid rods as well as amorphous and crystalline oligomers and polymers. The synthesis of perfectly defined oligomers in respect to emerging highly efficient and orthogonal chemistries will also be highlighted. magnified image
Nucleobase‐Mediated Stereospecific Radical Polymerization and Combination with RAFT Polymerization for Simultaneous Control of Molecular Weight and Tacticity
Authors: Tao Youhua , Satoh Kotaro , Kamigaito Masami 
Published: December 2010

AbstractA highly soluble thymine‐based compound (1‐octyl thymine), having an array of hydrogen bonding sites with an ADA sequence (A and D: proton acceptor and donor sites, respectively), was used to mediate the stereospecific radical polymerization of an acrylamide monomer [N‐(6‐acetamidopyridin‐2‐yl)acrylamide] possessing the complementary DAD sequence. The thymine derivative interacted with the monomer via the selective 1:1 and strong triple hydrogen‐bonding interaction (K = 1.1 × 103 in CHCl3 at 20 °C) and mediated the syndiospecific radical polymerization of the monomer to give syndiotactic rich polymers up to r = 84% in CH2Cl2 at −78 °C. A combination with the RAFT polymerization enabled simultaneous control of the molecular weight ($\overline {M} _{{\rm w}} /\overline {M} _{{\rm n}} $ ≈ 1.5) and tacticity (r = 73% and 76% at 60 and 20 °C, respectively) of the resulting polymers. Furthermore, the stereoblock polymerization was achieved upon the addition of the thymine‐based mediator during the RAFT polymerization to give the atactic‐syndiotactic stereoblock polymers with controlled molecular weights. magnified image
Nanoporous Network Channels from Self‐Assembled Triblock Copolymer Supramolecules
Authors: du Sart Gerrit Gobius , Vukovic Ivana , Vukovic Zorica , Polushkin Evgeny , Hiekkataipale Panu , Ruokolainen Janne , Loos Katja , ten Brinke Gerrit 
Published: December 2010

AbstractSupramolecular complexes of a poly(tert‐butoxystyrene)‐block‐polystyrene‐block‐poly(4‐vinylpyridine) triblock copolymers and less than stoichiometric amounts of pentadecylphenol (PDP) are shown to self‐assemble into a core–shell gyroid morphology with the core channels formed by the hydrogen‐bonded P4VP(PDP)complexes. After structure formation, PDP was removed using a simple washing procedure, resulting in well‐ordered nanoporous films that were used as templates for nickel plating. magnified image
Upper and lower trapezius muscle transfer to restore shoulder abduction and external rotation in longstanding upper type palsies of the brachial plexus in adults
Authors: Bertelli Jayme Augusto 
Published: December 2010

AbstractLesions affecting the upper roots of the brachial plexus result in paralysis of shoulder abduction and external rotation. In longstanding lesions, neurological surgery is not recommended in which case muscle transfers become an option to improve shoulder function. We describe the surgical treatment of seven adult patients with longstanding lesions of the upper roots of the brachial plexus, in whom the upper trapezius muscle was transferred to the humeral head, whereas the lower trapezius muscle was sutured to the infraspinatous muscle tendon. Within an average of 11.7 months after surgery, patients had recovered 38° of abduction and 104° of external rotation, as measured from full internal rotation. The results of this preliminary series involving the combined transfer of both the upper and lower trapezius muscle seems promising for the treatment of chronic paralysis of abduction and external rotation following brachial plexus injury. © 2010 Wiley‐Liss, Inc. Microsurgery, 2011.
Long‐term administration of BAY 41‐2272 prevents bladder dysfunction in nitric oxide‐deficient rats
Authors: Mónica Fabíola Z. , Reges Ricardo , Cohen David , Silva Fabio H. , De Nucci Gilberto , D'Ancona Carlos A.L. , Antunes Edson 
Published: December 2010

AbstractAimsChronic blockade of nitric oxide (NO) synthesis leads to detrusor smooth muscle overactivity. This study aimed to evaluate the protective effects of BAY 41‐2272, a soluble guanlylate cyclase activator, on changes in cystometric parameters in NO‐deficient rats.MethodsRats were divided into the following groups: (a) control, (b) DMSO, (c) Nω‐nitro‐L‐arginine methyl ester hydrochrolide (L‐NAME), (d) BAY 41‐2272 alone, and (e) L‐NAME + BAY 41‐2272. The NO synthase blocker L‐NAME (20 mg/rat/day) was giving in the drinking water concomitantly or not with BAY 41‐2272 (10 mg/kg/day, given by gavage).ResultsChronic L‐NAME treatment markedly increased the mean arterial blood pressure (MABP), and co‐treatment with BAY 41‐2272 nearly reversed L‐NAME‐induced rise on MABP. Non‐void contractions were significantly increased in L‐NAME group (0.90 ± 0.1 number/min) compared with either DMSO or control group (0.49 ± 0.1 number/min), which were prevented by co‐treatment with BAY 41‐2271 (0.56 ± 025 number/min; P < 0.05). The threshold pressure and peak pressure increased by 70% and 44% after chronic L‐NAME treatment, while co‐treatment with BAY 41‐2272 largely attenuated both of these effects (27% and 22% increase, respectively). The frequency of micturition cycles decreased by about of 50% in L‐NAME‐treated rats compared with control animals, and co‐treatment with BAY 41‐2272 normalized this parameter.ConclusionsOur data show that long‐term oral administration of BAY 41‐2272 counteracts the bladder dysfunction seen in NO‐deficient rats, indicating that restoration of the NO‐cGMP pathway by this compound may be of beneficial value to treat bladder symptoms. Neurourol. Urodynam. 30:456–460, 2011. © 2010 Wiley‐Liss, Inc.
Blood oxygenation level‐dependent (BOLD) total and extravascular signal changes and ΔR2* in human visual cortex at 1.5, 3.0 and 7.0 T
Authors: Donahue Manus J. , Hoogduin Hans , van Zijl Peter C. M. , Jezzard Peter , Luijten Peter R. , Hendrikse Jeroen 
Published: December 2010

AbstractThe characterisation of the extravascular (EV) contribution to the blood oxygenation level‐dependent (BOLD) effect is important for understanding the spatial specificity of BOLD contrast and for modelling approaches that aim to extract quantitative metabolic parameters from the BOLD signal. Using bipolar crusher gradients, total (b = 0 s/mm2) and predominantly EV (b = 100 s/mm2) gradient echo BOLD ΔR2* and signal changes (ΔS/S) in response to visual stimulation (flashing checkerboard; f = 8 Hz) were investigated sequentially (within < 3 h) at 1.5, 3.0 and 7.0 T in the same subgroup of healthy volunteers (n = 7) and at identical spatial resolutions (3.5 × 3.5 × 3.5 mm3). Total ΔR2* (z‐score analysis) values were −0.61 ± 0.10 s−1 (1.5 T), −0.74 ± 0.05 s−1 (3.0 T) and −1.37 ± 0.12 s−1 (7.0 T), whereas EV ΔR2* values were −0.28 ± 0.07 s−1 (1.5 T), −0.52 ± 0.07 s−1 (3.0 T) and −1.25 ± 0.11 s−1 (7.0 T). Although EV ΔR2* increased linearly with field, as expected, it was found that EV ΔS/S increased less than linearly with field in a manner that varied with TE choice. Furthermore, unlike ΔR2*, total and EV ΔS/S did not converge at 7.0 T. These trends were similar whether a z‐score analysis or occipital lobe‐based region‐of‐interest approach was used for voxel selection. These findings suggest that calibrated BOLD approaches may benefit from an EV ΔR2* measurement as opposed to a ΔS/S measurement at a single TE. Copyright © 2010 John Wiley & Sons, Ltd.
Real‐time volumetric MRI thermometry of focused ultrasound ablationin vivo: a feasibility study in pig liver and kidney
Authors: Quesson Bruno , Laurent Christophe , Maclair Gregory , de Senneville Baudouin Denis , Mougenot Charles , Ries Mario , Carteret Thibault , Rullier Anne , Moonen Chrit T.W. 
Published: December 2010

AbstractMR thermometry offers the possibility to precisely guide high‐intensity focused ultrasound (HIFU) for the noninvasive treatment of kidney and liver tumours. The objectives of this study were to demonstrate therapy guidance by motion‐compensated, rapid and volumetric MR temperature monitoring and to evaluate the feasibility of MR‐guided HIFU ablation in these organs. Fourteen HIFU sonications were performed in the kidney and liver of five pigs under general anaesthesia using an MR‐compatible Philips HIFU platform prototype. HIFU sonication power and duration were varied. Volumetric MR thermometry was performed continuously at 1.5 T using the proton resonance frequency shift method employing a multi‐slice, single‐shot, echo‐planar imaging sequence with an update frequency of 2.5 Hz. Motion‐related suceptibility artefacts were compensated for using multi‐baseline reference images acquired prior to sonication. At the end of the experiment, the animals were sacrificed for macroscopic and microscopic examinations of the kidney, liver and skin. The standard deviation of the temperature measured prior to heating in the sonicated area was approximately 1°C in kidney and liver, and 2.5°C near the skin. The maximum temperature rise was 30°C for a sonication of 1.2 MHz in the liver over 15 s at 300 W. The thermal dose reached the lethal threshold (240CEM43) in two of six cases in the kidney and four of eight cases in the liver, but remained below this value in skin regions in the beam path. These findings were in agreement with histological analysis. Volumetric thermometry allows real‐time monitoring of the temperature at the target location in liver and kidney, as well as in surrounding tissues. Thermal ablation was more difficult to achieve in renal than in hepatic tissue even using higher acoustic energy, probably because of a more efficient heat evacuation in the kidney by perfusion. Copyright © 2010 John Wiley & Sons, Ltd.
Poly(dimethylsiloxane)/palygorskite composites: preparation, characterization, and properties
Authors: Cheng Lijun , Li Zongqi , Zhang Zhijie 
Published: December 2010

AbstractPoly(dimethylsiloxane) (PDMS) composites were prepared by simple blending process using palygorskite (PG) or modified palygorskite (MP). This study has been designed to determine the influences of PG or MP on the thermal stability and the mechanical properties of PDMS composites. The thermal stability of PG and MP were also studied by thermogravimetric analysis (TGA). The results showed that MP had the similar thermal stability to PG, and PG or MP not only increased the thermal stability but also improved the mechanical properties of PDMS composites. Meanwhile, compared with PG/PDMS composites, MP/PDMS composites had better thermal stability and mechanical properties owing to the better dispersion of MP into the matrix, the stronger chemical interfacial interaction between MP and the matrix. Copyright © 2010 John Wiley & Sons, Ltd.
Ultra low field emission characteristics of chloride doped polypyrrole films
Authors: Patil Sandip S. , Jha Purushottam , Aswal D.K. , Gupta S.K. , Yakhmi J.V. , Joag Dilip S. , More Mahendra A. 
Published: December 2010

AbstractField emission characteristics of chloride doped polypyrrole (Cl‐PPy) films have been investigated. For this purpose, freestanding Cl‐PPy films have been synthesized by interfacial polymerization from two different monomer (pyrrole) concentrations (1 and 0.1 M), keeping the monomer to oxidant (FeCl3) concentration ratio equal to 1. The surface morphology of these Cl‐PPy films, as revealed from scanning electron microscopy, was found to be granular in nature. The average grain size of films prepared using 1 and 0.1 M pyrrole concentrations were ∼2.5 and ∼1 µm, respectively. The measured threshold field, that is, field required to draw an emission current density of 10 µA/cm2, for these two films were 0.27 and 0.15 V/µm, respectively. From these films, a maximum current density of 1 mA/cm2 could be drawn at an electric field of 0.42 and 0.29 V/µm, respectively. The field emission current (investigated at a preset value of 1 µA) was found to be very stable up to 3h, suggesting utility of Cl‐PPy films as a novel material for field emission based applications. Copyright © 2010 John Wiley & Sons, Ltd.
Preparation, properties, and application of polypropylene micro/nanofiber membranes
Authors: Zhu Mengjun , Xu Guanbiao , Yu Mingfei , Liu Yanbin , Xiao Ru 
Published: December 2010

AbstractNanofiber membranes have huge potential applications in many areas due to their unique properties. However, the thermoplastic micro/nanofiber membranes were rarely reported. In this paper, polypropylene (PP) nanofibers were prepared by melt extrusion of immiscible blends of PP, cellulose acetate butyrate (CAB), and subsequent removal of the CAB matrix. The wet‐laid application was used to make PP nanofiber membranes and PP‐g‐MAH/nonwoven micro/nanofiber membrane. The properties of membranes including morphology, apparent density, porosity, contact‐angle, pore size distribution, and water flux were characterized. The results showed that the consequent membranes were provided with optimistic porosity and pore size distribution. Moreover, they were all with high pure water fluxes, which were superior to that of PP microporous membrane. They performed an excellent separation performance of TiO2 suspension and dyeing wastewater. The work revealed this method could be an efficient one to make thermoplastic polymer micro/nanofiber membranes, and they would have a brilliant potential application for water treatment. Copyright © 2010 John Wiley & Sons, Ltd.
Fabrication, characterization and low‐velocity impact testing of hybrid sandwich composites with polyurethane/layered silicate foam cores
Authors: Njuguna James , Michałowski Sławomir , Pielichowski Krzysztof , Kayvantash Kambiz , Walton Andrew C. 
Published: December 2010

AbstractA series of nanophased hybrid sandwich composites based on polyurethane/montmorillonite (PU/MMT) has been fabricated and characterized. Polyaddition reaction of the polyol premix with 4,4′‐diphenylmethane diisocyanate was applied to obtain nanophased PU foams, which were then used for fabrication of sandwich panels. It has been found that the incorporation of MMT resulted in higher number of PU cells with smaller dimensions and higher anisotropy index (cross sections RI and RII). The obtained materials exhibited improved parameters in terms of thermal insulation properties. The results also show that nanophased sandwich structures are capable of withstanding higher peak loads than those made of neat PU foam cores when subject to low‐velocity impact despite their lower density than that of neat PU foams. This is especially significant for multi‐impact recurrences within the threshold loads and energies studied. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers
Electrical conductivity of urea–formaldehyde–cellulose composites loaded with copper
Authors: Pinto Gabriel , Maaroufi Abdel‐Karim , Benavente Rosario , Pereña José M. 
Published: December 2010

AbstractThis work is concerned with the preparation and characterization of composite materials prepared by compression molding of mixtures of copper powder and a commercial grade thermosetting resin of urea–formaldehyde filled with α‐cellulose in powder form. The electrical conductivity of the composites is <10−12 S/cm, unless the metal content reaches the percolation threshold of 24.0 vol %, beyond which the conductivity increases markedly by as much as 11 orders of magnitude, indicating an insulator–conductor phase transition. The homogeneity of these composites was checked by the morphologies of the constituents (filler and matrix) and the composites characterized by optical microscopy. The density of the composites was measured and compared with values calculated assuming different void levels within the samples to discuss the porosity effect. Finally, the obtained results on electrical conductivity have been well interpreted with the statistical percolation theory. The deduced critical parameters, such as the threshold of percolation, Vf*, the critical exponent, t, and the packing density coefficient, F, were in good accord with earlier studies. In addition, the hardness of samples remained almost constant with the increase of metal concentration. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers
Incorporation of titanium dioxide particles into polymer matrix using block copolymer micelles for fabrication of high refractive and transparent organic–inorganic hybrid materials
Authors: Yamada Shuhei , Mouri Emiko , Yoshinaga Kohji 
Published: December 2010

AbstractWe report a novel strategy for incorporation of titanium dioxide (TiO2) particles into poly(methyl methacrylate) (PMMA) to exploit high refractive and transparent organic–inorganic hybrid materials. Formation of TiO2 particles of around 20 nm was conducted within hydrophilic core of block copolymer micelles of poly(methyl methacrylate‐block‐acrylic acid) (PMMA‐b‐PAA) in toluene via sol–gel process from titanium isopropoxide and hydrochloric acid. Subsequently, incorporation of TiO2 particles into PMMA matrix was carried out by casting toluene solution of TiO2 precursor‐loaded copolymer micelles, prepared from PMMA350‐b‐PAA93 and the precursor of mole ratio Ti4+/carboxyl 4.0, and PMMA. Hybrid films of TiO2/PMMA exhibited high transparency to achieve transmission over 87% at 500 nm at 30 wt % of TiO2 content. The refractive index of resulting hybrid films at 633 nm linearly increased with TiO2 content to attain 1.579 at 30 wt % TiO2, which was 0.1 higher than that of PMMA. Cross‐sectional transmission electron microscope images of TiO2/PMMA hybrid films showed existence of TiO2 clusters less than 100 nm, which were probably formed by aggregation or agglutination of TiO2 particles during a drying process. It was also observed that decomposition temperature of the hybrid films elevated with increasing TiO2 content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Copoly(arylene ether nitrile) and copoly(arylene ether sulfone) ionomers with pendant sulfobenzoyl groups for proton conducting fuel cell membranes
Authors: Jutemar Elin Persson , Jannasch Patric 
Published: December 2010

AbstractThree series of fully aromatic ionomers with naphthalene moieties and pendant sulfobenzoyl side chains were prepared via K2CO3 mediated nucleophilic aromatic substitution reactions. The first series consisted of poly(arylene ether)s prepared by polycondensations of 2,6‐difluoro‐2′‐sulfobenzophenone (DFSBP) and 2,6‐dihydroxynaphthalene or 2,7‐dihydroxynaphthalene (2,7‐DHN). In the second series, copoly(arylene ether nitrile)s with different ion‐exchange capacities (IECs) were prepared by polycondensations of DFSBP, 2,6‐difluorobenzonitrile (DFBN), and 2,7‐DHN. In the third series, bis(4‐fluorophenyl)sulfone was used instead of DFBN to prepare copoly(arylene ether sulfone)s. Thus, all the ionomers had sulfonic acid units placed in stable positions close to the electron withdrawing ketone link of the side chains. Mechanically strong proton‐exchange membranes with IECs between 1.1 and 2.3 meq g−1 were cast from dimethylsulfoxide solutions. High thermal stability was indicted by high degradation temperatures between 266 and 287 °C (1 °C min−1 under air) and high glass transition temperatures between 245 and 306 °C, depending on the IEC. The copolymer membranes reached proton conductivities of 0.3 S cm−1 under fully humidified conditions. At IECs above ∼1.6 meq g−1, the copolymer membranes reached higher proton conductivities than Nafion® in the range between −20 and 120 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011