bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on sulfonic acid functionalized hollow silica spheres/Nafion® composite proton exchange membranes
Authors: Yuan Junjie , Pu Hongting , Yang Zhenglong 
Published: April 2009

AbstractIn this work, sulfonic acid functionalized hollow silica spheres (SAFHSS)/Nafion® composite membranes were prepared by a recasting procedure. The influences of temperature on water uptake, swelling degree, and proton conductivity of the composite membranes were studied. In comparison with the pure recast Nafion® membrane, it was found that water uptake of composite membranes increased with increasing SAFHSS loading at all temperature studied. The swelling degree of SAFHSS/Nafion® composite membranes with 10∼15 wt % SAFHSS loading was lower than that of the pure recast Nafion® at all temperatures in the study. The proton conductivity of SAFHSS/Nafion® composite membranes was constantly higher than that of the pure recast Nafion® at all temperatures (50∼130 °C). In a range from 50 to 130 °C, the highest conductivity of composite membranes was obtained when 10 wt % SAFHSS was loaded. The maximum conductivity reached 0.1 S cm−1 at 100% relative humidity and 100 °C, even the temperature reached to 130 °C, the conductivity of the composite membranes with 10 wt % SAFHSS was still as high as 4.4 × 10−2 S cm−1 at 100% relative humidity, whereas the conductivity of the pure recast Nafion® was only 2.2 × 10−3 S cm−1. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2647–2655, 2009
High quantum yield photoluminescence of new polyamides containing oligo‐PPV amino derivatives and related oligomers
Authors: Roviello Antonio , Borbone Fabio , Carella Antonio , Diana Rosita , Roviello Giuseppina , Panunzi Barbara , Ambrosio Antonio , Maddalena Pasqualino 
Published: April 2009

AbstractThe synthesis and the chemical physical characterization of new photoluminescent (PL) chromophores and polymers are reported. Chromophores (oligo‐PPV symmetric derivatives ending with amino groups) are strong blue emitters with a PL quantum yield of ∼70% in dioxane solution. They have been used to prepare polyamides by reaction with aliphatic acyl dichlorides in which emitting and non emitting units are alternated. PL properties of the synthesized polyamides have been evaluated in solution and reveal a strong blue emission (PL quantum yield ∼60%), To increase the solubility of these systems, oligomers have been purposely prepared and then characterized. They show a peculiar white emission when excited in DMF solution; to get insight into this interesting behavior, asymmetric monoacetylated chromophores have been prepared as model compounds for the chromophoric end groups of the polyamide chains. The emission spectra of these compounds reveal a broad excimeric yellow emission which is responsible, along with the blue emission of the inner chromophoric units, of the overall white emission of the oligomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2677–2689, 2009
Synthesis and characterization of side‐chain liquid crystalline polymers bearing cholesterol mesogen
Authors: Ahn Suk‐Kyun , Nguyen Le Long T. , Kasi Rajeswari M. 
Published: April 2009

AbstractA series of new norbornene carboxylic cholesteryl ester monomers with and without alkyl spacers, NBCh, and NBCh‐n, respectively, were synthesized. New side‐chain liquid crystalline homopolymers, PNBCh and PNBCh‐n, were cleanly prepared using NBCh and NBCh‐n, respectively, with Grubbs 2nd generation catalyst. Molecular and structural characterization of monomers and polymers were carried out by nuclear magnetic resonance, NMR, Fourier transform infrared, FT‐IR, spectroscopy, and gel permeation chromatography, GPC. The thermal and liquid crystalline properties of the homopolymers were investigated by differential scanning calorimetry, DSC, thermogravimetric analysis, TGA, and polarized optical microscopy, POM. Small angle and wide angle X‐ray studies of PNBCh‐n in powder and fiber states not only confirmed the formation of smectic A mesophases, but also established their morphologies. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2690–2701, 2009
Nanostructural modifications of polyamide/MMT hybrids under isothermal and nonisothermal elongational flow
Authors: Garofalo E. , Russo G. M. , Scarfato P. , Incarnato L. 
Published: April 2009

AbstractThe aim of this work is to investigate the effects of elongational flow on the nanoscale arrangement of the silicate inside polyamide‐based nanocomposites. Hybrids, at different loadings of a commercial organoclay, were produced by melt compounding using two polyamide matrices, a nylon‐6, and a copolyamide with similar molecular weight and rheological properties. The elongational flow characterization was performed under both isothermal and nonisothermal conditions by using, respectively, an elongational rheometer (SER) and a fiber‐spinning technique. The extensional rheological response of melt‐compounded nanocomposites, correlated to TEM and X‐ray analyses, was used to probe the nanostructural modifications developed during the uniaxial stretching. The results demonstrated that isothermal and nonisothermal elongational flow can modify the nanomorphology of the nanocomposite hybrids affecting the degree of silicate exfoliation as well as the extent of silicate orientation upon the stretching direction. The entity of structural modifications induced by the stretching were highly dependent on the initial nanomorphological state and on the polymer‐clay affinity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 981–993, 2009
Viscoelastic properties of nanosilica‐filled epoxy composites investigated by dynamic nanoindentation
Authors: Zhang Yang‐Fei , Bai Shu‐Lin , Li Xiong‐Kui , Zhang Zhong 
Published: April 2009

AbstractThe viscoelastic properties of the epoxy filled with silica nanoparicles have been investigated by dynamic nanoindentation and characterized by the storage modulus and loss tangent. The materials studied are neat epoxy and silica/epoxy composites with silica volume fraction of 1, 3, 6, 10, and 14 vol %, respectively. The silica nanoparticles with an average diameter of 25 nm are found to disperse homogeneously in the epoxy matrix. The effect of the particle content, force frequency, and penetration load on the viscoelastic behavior is studied and discussed. The comparison with traditional testing methods such as tension, bending, and DMTA is made. Besides, theoretical results by using micromechanics models are also obtained and compared with the experimental results. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1030–1038, 2009
Improvement of Surface Characteristics by Electroplating Hard Chromium Coating Post Treated by Nanocrystalline Plasma Electrolytic Carbonitriding
Authors: Mofidi Seyed Haman Hedayat , Aliofkhazraei Mahmood , Rouhaghdam Alireza Sabour , Ghobadi Ehsan , Mohsenian Ehsan 
Published: April 2009

AbstractNanocrystalline carbonitrides were performed by pulsed plasma electrolytic carbonitriding on hard chromium coating deposited on AISI 1035 substrate by electroplating. The electroplated samples were connected cathodically to a high‐current pulsed power supply and biased to a negative voltage. The treatment times were 30, 60 and 60 min. A thick compound layer was formed on the surface of Cr coating with microhardness of about 1 200 HV0.15. The nanostructure of the treated layers depends strongly on the applied voltage. The wear resistance of the treated layers depended on process parameters. Overall mechanical properties of treated samples show strong relation to morphology and distribution of complex carbonitride nanocrystallites.
Effect of He/CF4 DBD Operating Parameters on PET Surface Modification
Authors: Jacobs Tinneke , Morent Rino , De Geyter Nathalie , Leys Christophe 
Published: April 2009

AbstractIn this paper, a dielectric barrier discharge (DBD) operated at (sub)atmospheric pressure in a 95/5% He/CF4 mixture is employed to increase the hydrophobicity of a poly(ethylene terephthalate) (PET) film. This paper studies the influence of different operating parameters on the hydrophobic properties of the PET film using contact angle measurements. Results clearly show that the hydrophobicity of the PET film is only enhanced when using large gas flows. Moreover, this work demonstrates that operating pressure and discharge power have a significant influence on the rate of plasma modification as well as on the uniformity of the plasma treatment. Also important to mention is that no ageing effect is observed. As a result, one can conclude that the utilized DBD is an efficient tool to create stable, hydrophobic PET surfaces.
High macrolide resistance inStreptococcus pyogenesstrains isolated from children with pharyngitis in China
Authors: Liu Xiaorong , Shen Xuzhuang , Chang Hesheng , Huang Guoying , Fu Zhou , Zheng Yuejie , Wang Libo , Li Chengrong , Liu Lan , Shen Ying , Yang Yonghong 
Published: April 2009

AbstractObjectivesTo assess the macrolide resistance, phenotype, and genotypic characterization ofStreptococcus pyogenesisolated from Chinese children with pharyngitis.MethodsMinimal inhibitory concentration (MIC) with nine antibiotics was determined on 188 isolates ofS. pyogenescollected from outpatients with pharyngitis in four children's hospitals in different regions of China in 2007. MICs of penicillin, chloramphenicol, cefradine, levofloxacin, macrolide (erythromycin, clarithromycin, azithromycin,), clindamycin, and tetracycline were determined by the microdilution method. The macrolide resistant phenotypes of isolates were determined through a double‐disk. The macrolide‐resistant genes (mefA,ermB, andermA) were amplified by polymerase chain reaction (PCR).ResultsOver 95% were resistant to macrolides, while 92.0% were resistant to tetracycline. We also found that all isolates were sensitive to penicillin, chloramphenicol, cefradine, and levofloxacin. Among the 173 erythromycin resistant strains, 171 (98.8%) were assigned to the cMLS phenotype, while the remaining 2 (1.2%) were assigned to the iMLS phenotype. Among the 171 cMLS isolates, 168 isolates (98.2%) had theermBgene accounting for 98.2%. Meanwhile, 2 iMLS isolates had theermAgene. Macrolides were highly resistant toermBpositive strains (MIC90 > 256 µg/ml). Neither the M‐phenotype nor themefAgene was detected. Meanwhile, our studies of multiple centers showed that consumption of macrolides from 2000 to 2006 was very high.ConclusionThe main phenotype is cMLS, and theermBgene code is the main resistance mechanism against macrolides inS. pyogenes. The high rate of macrolide resistance toS. pyogeneswas observed, which may be correlated with the overuse of these antibiotics in China. Pediatr Pulmonol. 2009; 44:436–441. © 2009 Wiley‐Liss, Inc.
Spirometry reference values for Navajo children ages 6–14 years
Authors: Arnall David A. , Kanuho Verdell , Interpreter Christina , Nelson Arnold G , Coast J. Richard , Eisenmann Joey C. , Enright Paul L. 
Published: April 2009

AbstractSpirometry is the most important tool in diagnosing pulmonary disease and is the most frequently performed pulmonary function test. Since respiratory disease is the single greatest cause for morbidity and mortality on the Navajo Nation, the purpose of this study was to create new age and race‐specific pulmonary nomograms for Navajo children. Five hundred fifty‐eight healthy children, ages 6–14 years, attending Navajo Nation elementary schools in Arizona, were asked to perform spirometry to develop population‐specific and tribe‐specific nomograms for forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), and FEV1 Ratio (FEV1/FVC). Spirometry tests from 284 girls and 274 boys met American Thoracic Society quality control standards. Lung function values, except for FEV1/FVC, all increased with height. The lower limit of the normal range for FEV1/FVC was 80%. The spirometry reference equations from the healthy boys and girls were developed. Height and the natural log of height were significant predictors of FEV1, FVC, and FEF25–75% in the gender‐specific models. The resulting population‐specific spirometry reference equations should be used when testing Navajo children ages 6–14 years. However, the use of the NHANES III spirometry reference equations for Caucasian children may not result in significant misclassification in clinical settings providing that a maximal effort is given by the Navajo child being tested. Pediatr Pulmonol. 2009; 44:489–496. © 2009 Wiley‐Liss, Inc.
Temperature‐induced partially unfolded state of hUBF HMG Box‐5: Conformational and dynamic investigations of the Box‐5 thermal intermediate ensemble
Authors: Liu Zhijun , Zhang Jiahai , Wang Xingsheng , Ding Yanwei , Wu Jihui , Shi Yunyu 
Published: April 2009

AbstractHuman upstream binding factor (hUBF) HMG Box‐5 is a highly conserved protein domain, containing 84 amino acids and belonging to the family of the nonspecific DNA‐binding HMG boxes. Its native structure adopts a twisted L shape, which consists of three α‐helices and two hydrophobic cores: the major wing and the minor wing. In this article, we report a reversible three‐state thermal unfolding equilibrium of hUBF HMG Box‐5, which is investigated by differential scanning calorimetry (DSC), circular dichroism spectroscopy, fluorescence spectroscopy, and NMR spectroscopy. DSC data show that Box‐5 unfolds reversibly in two separate stages. Spectroscopic analyses suggest that different structural elements exhibit noncooperative transitions during the unfolding process and that the major form of the Box‐5 thermal intermediate ensemble at 55°C shows partially unfolded characteristics. Compared with previous thermal stability studies of other boxes, it appears that Box‐5 possesses a more stable major wing and two well separated subdomains. NMR chemical shift index and sequential 1HNi‐1HNi+1 NOE analyses indicate that helices 1 and 2 are native‐like in the thermal intermediate ensemble, while helix 3 is partially unfolded. Detailed NMR relaxation dynamics are compared between the native state and the intermediate ensemble. Our results implicate a fluid helix‐turn‐helix folding model of Box‐5, where helices 1 and 2 potentially form the helix 1‐turn‐helix 2 motif in the intermediate, while helix 3 is consolidated only as two hydrophobic cores form to stabilize the native structure. Proteins 2009. © 2009 Wiley‐Liss, Inc.
Surfactant‐induced deposit structures in relation to the biological efficacy of glyphosate on easy‐ and difficult‐to‐wet weed species
Authors: Kraemer Thorsten , Hunsche Mauricio , Noga Georg 
Published: April 2009

AbstractBACKGROUND: Typical active ingredient (AI) residue patterns are formed during droplet drying on plant surfaces owing to the interaction of spray solution characteristics and leaf micromorphology. Currently, comparatively little is known about the influence of AI deposit patterns within a spray droplet residue area on the penetration and biological efficacy of glyphosate. A scanning electron microscope with energy dispersive X‐ray microanalysis has been used to characterise residue patterns and to quantify the area ultimately covered by glyphosate within the droplet spread area.RESULTS: The easy‐to‐wet weed species Stellaria media L. and Viola arvensis L., as well as the difficult‐to‐wet Chenopodium album L. and Setaria viridis L., differing in their surface micromorphology, have been used. Rapeseed oil ethoxylates (RSO 5 or RSO 60) were added to glyphosate solutions to provide different droplet spread areas. Addition of RSO 5 enhanced droplet spread area more than RSO 60, and both caused distinct glyphosate residue patterns. The biological efficacy of treatment solutions showed no significant correlation with the area ultimately covered by glyphosate.CONCLUSION: The results have implications on herbicide uptake models. This study shows that droplet spread area does not correspond to the area ultimately covered by glyphosate, and that the latter does not affect glyphosate phytotoxicity. Copyright © 2009 Society of Chemical Industry
Mixture effects on the glow peak temperature of europium doped binary crystals
Authors: Rodríguez‐Mijangos R. , Perez‐Salas R. 
Published: April 2009

AbstractThermoluminescence measurements of beta‐irradiated divalent Europium doped binary divalent alkali halides with RbCl and KBr components at several compositions x have been obtained. A characteristic thermoluminescence glow peak for each concentration is identified and its temperature, varying from 373 to 458 K, is seen to be dependent on composition. The temperature shift is analyzed as an ion size effect. It is stronger when the halogen ions are interchanged, resembling that the recombination of a halogen vacancy with a hole is the principal source of the thermoluminescence glow peaks. The arguments above are used to predict in a gross manner the temperature of the principal thermoluminiscence glow peaks in different halogen families. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of Bi2O3‐GeO2 glass phosphor co‐doped with Yb3+, Nd3+ for optical coherence tomography light source
Authors: Sakano A. , Mizutani R. , Fuchi S. , Takeda Y. 
Published: April 2009

AbstractWe have investigated spectroscopic properties of Bi2O3‐GeO2 glass co‐doped with Yb3+ and Nd3+ to find appropriate phosphors for an optical coherence tomography (OCT) light source. We have successfully obtained a Gaussian‐like shaped spectrum from 6.0 Yb2O3–5.0 Nd2O3–44.0 Bi2O3–44.0 GeO2–1.0 Sb2O3 (in nominal molar composition) with a full width at half maximum (FWHM) of 91 nm in the wavelength region near 1000 nm. We achieved the luminescence efficiency of 1.4% using a green LED. The interference signal was studied by using a Michelson interferometer. As a result, the coherent length of 5.7 μm was achieved. This value indicates that the depth resolution of the OCT with this light source is twice compared with that of conventional SLDs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of stimulated Raman pumping toward the first study of chemical reaction dynamics of the muonium atom with H2*
Authors: Sukhorukov Oleksandr , Bakule Pavel , Matsuda Yasuyuki , Kamal Saeid , Momose Takamasa , Fleming Donald 
Published: April 2009

AbstractThe chemical reaction of interest, from the field of μSR spectroscopy, is that of the muonium atom (Mu) with molecular hydrogen in its first vibrational excited state. The stimulated Raman pumping (SRP) technique has been used to prepare H2 in its ν = 1 state in a series of off‐line experiments at the LASIR Lab at UBC. Three different SRP excitation schemes employing the second harmonic of a Nd:YAG laser have been analysed in connection with this application, for 5.5, 13, and 26 cm‐long reaction cells. The laser energy varied from ∼80 to ∼550 mJ/pulse (or from ∼0.07 GW/cm2 to ∼0.46 GW/cm2) at a 10 Hz repetition rate. The importance of injection seeding of the Nd:YAG laser for efficient molecular excitation is shown. The major challenge of this experiment was to ensure a homogeneous excitation over a large volume (few cm3) while achieving a high amount of vibrationally excited H2 (3‐15 Torr). This is demanded by the requirements of superposition of a pulsed muon beam with the laser beam and the expected rate constant of the Mu + H2*(ν=1) →MuH + H reaction. In this endeavour it was also of interest to explore the effect of added moderator gas to the hydrogen and so the effect of Ar/Xe moderator on the efficiency of hydrogen pumping for different SRP excitation schemes is also shown. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical characterization of pseudo‐ordered nanostructured thin films
Authors: Taschuk M. T. , Chai J. , Buriak J. M. , Brett M. J. 
Published: April 2009

AbstractWe have demonstrated the use of tetrahydrofuran (THF) annealed self‐assembled monolayers of polystyrene‐b ‐poly(2‐vinylpyridine) diblock copolymer to produce hexagonal close packed metallic nanoarrays which may be used as substrates to produce ordered nanostructured optical thin films using glancing‐angle deposition. Our film connects the sites of a face‐centered cubic lattice using a triangular spiral deposited on the block copolymer seeds. The optical properties of unseeded and seeded triangular spiral thin films are characterized. While the nanostructured thin films can inherit the periodicity of the underlying seeds, the optical performance is less than that of an unseeded film. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selective formation of dequenched aggregates of rhodamines: comparison with J‐ and H‐aggregates
Authors: Tomioka Akihiro , Kamiyama Yasushi , Fujimoto Atsushi , Kawakami Shin'ya 
Published: April 2009

AbstractSelf‐organized rhodamine aggregates prepared by wetting / dewetting process of an ethanol solution on a hydrophilic glass surface consistently exhibited fluorescence without quenching. Upon annealing, the aggregates exhibited an irreversible transition to quenched state, similar to H‐aggregate, whereas the fluorescence spectrum was unchanged. The as grown highly fluorescent aggregate is a novel aggregate, neither a J‐aggregate nor an H‐aggregate, showing a blue‐shifted excitation spectrum whereas the emission spectrum is similar to that of molecularly dispersed solution. This fluorescent aggregate was only realized in nonequilibrium by the rapid dewetting process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conservative cascade interpolation on the sphere: An intercomparison of various non‐oscillatory reconstructions
Authors: Norman Matthew R. , Semazzi Fredrick H. M. , Nair Ramachandran D. 
Published: April 2009

AbstractVarious new polynomial and non‐polynomial approximations to a subgrid distribution have been adapted for use in the conservative cascade scheme (CCS) and applied to conservative grid‐to‐grid interpolation on a latitude‐‐longitude grid. These approximations include the following: piecewise parabolic method (PPM), piecewise hyperbolic method (PHM), piecewise double hyperbolic method (PDHM), power‐limited piecewise parabolic method (P‐PPM), piecewise rational method (PRM), third‐order weighted essentially non‐oscillatory (WENO23), fifth‐order weighted essentially non‐oscillatory (WENO35), and a modified piecewise parabolic method (M‐PPM). A series of test cases are performed in which initial gridded data are interpolated between T42 and 2° grids and compared against analytical values. Four initial data profiles are used: smooth harmonic, high‐frequency harmonic, quasi‐polar vortex data and slotted cylinder data. In general, PDHM (WENO35) had the lowest error norms of the three‐(five‐)cell stencil methods. Quite often, M‐PPM gave accuracy comparable to WENO35 at significantly lower cost. Monotonicity violations generally only occurred when interpolating to a finer grid with a maximum violation of 1.8% of the data range. Copyright © 2009 Royal Meteorological Society