bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poly(methyl methacrylate)‐coated carbonyl iron particles and their magnetorheological characteristics
Authors: Jiang Wanquan , Zhu Hong , Guo Chaoyang , Li Jianfeng , Xue Qun , Feng Jianghua , Gong Xinglong 
Published: March 2010

AbstractMagnetorheological fluids (MRFs) are types of suspensions that contain magnetic particles and a carrier fluid, and are considered as semi‐active smart materials. By tuning the strength of an external magnetic field, like other traditional MRFs, a carbonyl iron (CI)–poly(methyl methacrylate) (PMMA) particle‐based MRF can change reversibly from a fluid‐like state to a solid‐like state within milliseconds. In the research reported, CI particles were encapsulated with PMMA via emulsion polymerization. After the polymerization, the fabricated CI–PMMA composite particles were dispersed in a suspension medium to prepare MRF. The synthesized CI–PMMA composite particle‐based MRF showed a shear stress of 60 kPa at the magnetic field strength of 0.6 T, and a greatly enhanced anti‐sedimentation stability. Copyright © 2010 Society of Chemical Industry
Investigation of clay modifier effects on the structure and rheology of supercritical carbon dioxide‐processed polymer nanocomposites
Authors: Bellair Robert J. , Manitiu Mihai , Gulari Esin , Kannan Rangaramanujam M. 
Published: March 2010

AbstractSuperior property enhancements in polymer–clay nanocomposites can be achieved if one can significantly enhance the nanoclay dispersion and polymer–clay interactions. Recent studies have shown that nanoclays can be dispersed in polymers using supercritical carbon dioxide (scCO2). However, there is need for a better understanding of how changing the clay modifier affects the clay dispersability by scCO2 and the resultant nanocomposite rheology. To address this, the polystyrene (PS)/clay nanocomposites with “weak” interaction (Cloisite 93A clay) and “strong” interaction (Cloisite 15A clay) have been prepared using the supercritical CO2 method in the presence of a co‐solvent. Transmission electron microscopy images and small‐angle X‐ray diffraction illustrate that composites using 15A and 93A clays show similar magnitude of reduction in the average tactoid size, and dispersion upon processing with scCO2. When PS and the clays are coprocessed in scCO2, the “dispersion” of clays appears to be independent of modifier or polymer–clay interaction. However, the low‐frequency storage modulus in the scCO2‐processed 15A nanocomposites is two orders of magnitude higher than that of 93A nanocomposites. It is postulated that below percolation (solution blended composites), the strength of polymer–clay interaction is not a significant contributor to rheological enhancement. In the scCO2‐processed nanocomposites the enhanced dispersion passes the percolation threshold and the interactions dictate the reinforcement potential of the clay–polymer–clay network. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 823–831, 2010
Quantitative analysis of near surfaces three‐dimensional orientation of polymer chains in PET and PEN films using polarized ATR FTIR spectroscopy
Authors: Momose Miho , Ando Shinji 
Published: March 2010

AbstractPolarized attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy was utilized to characterize the three‐dimensional orientation of polymer chains near highly anisotropic surfaces generated by uniaxial drawing. A versatile method was proposed to analyze the molecular orientation of the polymers by combining the experimental refractive indices and optimized contact pressure by an anvil for solving the optical contact problem. This method is effective even when changes in the molecular orientation along the thickness direction caused by drawing are remarkable. In addition, this method enables quantitative comparison of the molecular orientation among different polymers in the same coordinate system. From the molecular orientation analysis of poly (ethylene terephthalate) (PET) and poly (ethylene naphthalate) (PEN), it was revealed that this method has a broader range of applications with high accuracy in estimating the molecular orientation of polymers compared with the conventional methods. The significant changes in the molecular orientation caused by uniaxial and biaxial drawing of PET and PEN films were quantitatively analyzed, and the reasons for the significant in‐plane orientation of PEN chains on the film plane are discussed. In addition, the difference in the molecular orientation between both sides of the films was also demonstrated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 870–879, 2010
The structure and electric characters of proton‐conducting chitosan membranes with various ammonium salts as complexant
Authors: Du J. F. , Bai Y. , CHU W. Y. , Qiao L. J. 
Published: March 2010

AbstractThe structural and electric properties of chitosan electrolytes doped by three different ammonium salts [CH3COONH4, NH4Cl, and (NH4)2SO4] were discussed. The chitosan electrolytes were prepared by solution casting technique. The results show that the addition of ammonium salts leads to: The formation of complexation between ammonium salts and chitosan matrix, the destruction of crystal forms, and the enhancement of amorphous nature. With the rise of salt content, both the glass transition temperature and the activation energy show a “V”‐type trend, whereas the conductivity exhibits a reverse trend. For different ammonium salts, the electric properties of the chitosan electrolyte are different due to the Coulomb force between anion of salts and functional groups. The CH3COONH4 doped chitosan electrolyte exhibits the optimum electric properties, whereas those of (NH4)2SO4 doped chitosan electrolyte are worst. The chitosan electrolyte doped with 40 wt % CH3COONH4 has the lowest glass transition temperature of 369 K, the lowest activation energy of 0.19 eV, and the highest ionic conductivity of 2.87 × 10−4 S cm−1 at room temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 880–885, 2010
Multiscale Lagrangian fluid dynamics simulation for polymeric fluid
Authors: Murashima Takahiro , Taniguchi Takashi 
Published: March 2010

AbstractWe have developed a simulation technique of multiscale Lagrangian fluid dynamics to tackle hierarchical problems relating to historical dependency of polymeric fluid. We investigate flow dynamics of dilute polymeric fluid by using the multiscale simulation approach incorporating Lagrangian particle fluid dynamics technique (the modified smoothed particle hydrodynamics) with stochastic coarse‐grained polymer simulators (the dumbbell model). We have confirmed that our approach is well in agreement with the macroscopic results obtained by a constitutive equation corresponding to the dumbbell model, and observed that microscopic thermal fluctuation appears in macroscopic fluid dynamics as dispersion phenomena. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 886–893, 2010
Effects of chain conformation and chain length on degree of aggregation in assembled particles of conjugated polymer in solvents–nonsolvent: A spectroscopic study
Authors: Traiphol Rakchart , Potai Ruttayapon , Charoenthai Nipaphat , Srikhirin Toemsak , Kerdcharoen Teerakiat , Osotchan Tanakorn 
Published: March 2010

AbstractThis article explores photophysical properties and aggregation behaviors of conjugated polymer, poly[2‐methoxy, 5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene](MEH−PPV), in various solvent–nonsolvent systems by utilizing UV/vis absorption and photoluminescence (PL) spectroscopy. The isolated chains of MEH‐PPV dispersed in solvents including dichloromethane, chloroform, and tetrahydrofuran adopt either extended or collapsed conformations depending on local polymer–solvent interactions. Aggregation of the MEH‐PPV in these solvents is induced by addition of a poor solvent, cyclohexane. The formation of aggregates is indicated by the appearance of distinct red‐shift peaks in the absorption and PL spectra. The degree of aggregation in each solvent–nonsolvent system is compared by means of absorbance and PL intensity of the aggregate bands. In early stage of the aggregation, the amount of aggregates in system is controlled by the solubility of polymer. When the polymer chains are forced to densely pack within assembled particles by increasing ratio of cyclohexane to 99 v/v %, the conformation of individual chain plays important role. We have found that the extended chains facilitate the aggregation in the assembled particles. Increasing chain length of polymer promotes the aggregation in early stage and densely packed particles. Size distribution of the assembled particles is also found to depend on the choice of solvent. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 894–904, 2010
Ar/HMDSO/O2 Fed Atmospheric Pressure DBDs: Thin Film Deposition and GC‐MS Investigation of By‐Products
Authors: Fanelli Fiorenza , Lovascio Sara , d'Agostino Riccardo , Arefi‐Khonsari Farzaneh , Fracassi Francesco 
Published: March 2010

AbstractThe thin film deposition in DBDs fed with Ar/HMDSO/O2 mixtures was studied by comparing the FT‐IR spectra of the deposits with the GC‐MS analyses of the exhaust gas. Under the experimental conditions investigated, oxygen addition does not enhance the activation of the monomer while it highly influences the chemical composition and structure of the deposited coating as well as the quali‐quantitative distribution of by‐products in the exhaust. Without oxygen addition a coating with high monomer structure retention is obtained and the exhaust contains several by‐products such as silanes, silanols, and linear and cyclic siloxanes. The dimethylsiloxane unit seems to be the most important building block of oligomers. Oxygen addition to the feed is responsible for an intense reduction of the organic character of the coating as well as for a steep decrease, below the quantification limit, of the concentration of all by‐products except silanols. Some evidences induce to claim that the silanol groups contained in the deposits are formed through heterogeneous (plasma‐surface) reactions.magnified image
Scattering of charged tensor bosons in gauge and superstring theories
Authors: Antoniadis I. , Savvidy G. 
Published: March 2010

AbstractWe calculate the leading‐order scattering amplitude of one vector and two tensor gauge bosons in a recently proposed non‐Abelian tensor gauge field theory and open superstring theory. The linear in momenta part of the superstring amplitude has identical Lorentz structure with the gauge theory, while its cubic in momenta part can be identified with an effective Lagrangian which is constructed using generalized non‐Abelian field strength tensors.
Bioactivity against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) of Cymbopogon citratus and Eucalyptus citriodora essential oils grown in Colombia
Authors: Olivero‐Verbel Jesús , Nerio Luz S , Stashenko Elena E 
Published: March 2010

AbstractBACKGROUND: Essential oils isolated from Cymbopogon citratus (DC) Stapf. and Eucalyptus citriodora Hook grown in Colombia were analysed by gas chromatography–mass spectrometry (GC‐MS) and tested for repellent activity and contact toxicity against Tribolium castaneum (Herbst.) (Coleoptera: Tenebrionidae).RESULTS: The main components of C. citratus oil were geranial (34.4%), neral (28.4%) and geraniol (11.5%), whereas those of E. citriodora were citronellal (40%), isopulegol (14.6%) and citronellol (13%). The mean repellent doses after 4 h exposure were 0.021 and 0.084 mL L−1 for C. citratus and E. citriodora oils respectively—values lower than that observed for the commercial product IR3535 (0.686 mL L−1).CONCLUSION: These studies showed the composition and repellent activity of essential oils of C. citratus and E. citriodora, suggesting that these are potential candidates as insect repellents. Copyright © 2010 Society of Chemical Industry
Controlling the conductivity of InN
Authors: Van de Walle C. G. , Lyons J. L. , Janotti A. 
Published: March 2010

AbstractInN has emerged as a highly promising material for a number of technological applications, but progress is still hampered by lack of control over its conductivity. The material exhibits a high tendency for unintentional n‐type conductivity, both in the bulk and on the surface. We discuss the origins of this conductivity, considering point defects, impurities, and surface states. First‐principles calculations based on density functional theory, with suitable band‐gap corrections, have been fruitfully applied to investigate doping issues. The results indicate that native point defects are unlikely to be the source of bulk conductivity and that attention should be focused on unintentional incorporation of impurities. In particular, hydrogen is a prime candidate for shallow donors in InN. Both interstitial and substitutional hydrogen have high solubility and give rise to n‐type conductivity. Substitutional hydrogen consists of H sitting on a nitrogen site, bonding equally to the four In nearest neighbors in a multicenter‐bond configuration (a highly unusual type of chemical bond). Substitutional hydrogen, somewhat counterintuitively, is a double donor. With regard to p‐type doping, Mg is a promising acceptor in InN. Its ionization energy is ∼0.2 eV and it has lower formation energy in InN than in GaN. The problems encountered in p‐type doping of InN are therefore not due to the properties of the acceptor, but to compensation by native defects or unintentional impurities acting as donors. In addition to the bulk conductivity, accumulation of electrons has been almost universally observed on InN surfaces. While donor impurities adsorbed on the surface could of course contribute to this conductivity, we have proposed that the accumulation layers are an intrinsic property of the material that can be attributed to the fact that on polar surfaces occupied surface states are located above the conduction‐band minimum (CBM). Fermi‐level pinning occurs due to occupied surface states above the CBM, for all In/N ratios, thus explaining the observed electron accumulation. Interestingly, we have found an absence of electron accumulation on nonpolar surfaces of InN at moderate In/N ratios, in agreement with experimental observations on cleaved surfaces. Consequences for growth as well as for devices will be discussed.
Effects of pressure and inter‐electrode distance on deposition of nanocrystalline silicon under high pressure conditions
Authors: Liu Yanchao , Verkerk Arjan D. , Rath Jatindra K. , Schropp Ruud E. I. , Goedheer Wim J. 
Published: March 2010

AbstractPressure (p) and inter‐electrode distance (d) are important parameters in the process of depositing hydrogenated nanocrystalline silicon (nc‐Si:H) by very high frequency plasma enhanced chemical vapour deposition (VHF PECVD). High quality nc‐Si:H materials are normally deposited at high pressure (1 mbar < p < 7 mbar). However, systematic research on the combined effects of p and d is rare. In order to optimize nc‐Si:H for solar cells, such effects are investigated for a silane‐hydrogen discharge at high pressure conditions. All nc‐Si:H layers were deposited at fixed hydrogen dilution ratio (H2/SiH4), power and frequency. With optical emission spectroscopy, direct images taken by a photo camera and by 1D SiH4/H2 plasma simulation, three different series were analyzed to study the combined effects of p and d at high pressure. The effects on the crystalline ratio and the porosity of the deposited silicon layers were also investigated. When the p ·d product is constant, the plasma sheath becomes relatively thinner when d increases. When p or d increases independently, the electron density decreases. All the above modifications can increase the deposition rate, but by different mechanisms. When nc‐Si:H is deposited at a p ·d product of 30 mbar·mm, compact material with high crystalline ratio is obtained (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
PS‐NH2 + PMMA‐COOH blend: A promising substrate material for the deposition of densely packed gold nanoparticles
Authors: Božanić D. K. , Ivković M. , Bibić N. , Hegewald J. , Pionteck J. , Žikić R. , Djoković V. 
Published: March 2010

AbstractDensely packed gold nanoparticles with narrow size distribution were fabricated by pulsed laser deposition using a blend of amino‐terminated polystyrene (PS‐NH2) and carboxyl‐terminated polymethylmethacrylate (PMMA‐COOH) as a deposition substrate. Transmission electron microscopy showed spherical Au nanoparticles with an average size of 5 nm. UV–vis absorption spectra of the Au/blend nanocomposite films exhibited a strong resonance band at 658 nm. The analyses of the spectrum using the effective medium Bergman theory showed that the nanocomposite is comprised of isolated and randomly arranged nanoparticles. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The essential ingredients leading to the explosive growth stage of the European wind storm Lothar of Christmas 1999
Authors: Rivière G. , Arbogast P. , Maynard K. , Joly A. 
Published: March 2010

AbstractKey dynamical ingredients leading to the explosive growth stage of the extratropical wind storm Lothar (24–26 December 1999) are identified by performing numerical sensitivity experiments using the Météo‐France operational model. This stage suddenly occurred when the surface cyclone crossed the upper‐level jet in its exit region. The model is shown to capture quite well the whole process by starting the forecast 12 h before the start of the explosive growth stage.A first set of experiments consists of revisiting the role of humidity and other physical processes. A run suppressing latent heating does not exhibit any cyclone growth, similar to a previous study by other authors. However, a frictionless dry adiabatic run, i.e. when latent heating processes and dissipation terms are both suppressed, is shown to reproduce the timing and the location of the rapid intensification stage but not its intensity (which is overestimated). Moist processes are thus crucial because they compensate for the dissipation terms, but the vertical coupling between the surface cyclone and the upper‐level jet can be reproduced and interpreted in terms of frictionless dry adiabatic interactions, at least for conceptual purposes.All the other numerical experiments have the full physics of the model and only differ in their initial conditions. The modification of the flow is performed using a recently developed potential vorticity inversion method. Upper‐level high‐frequency anomalies are shown to have only a moderate impact on the rapid deepening of the surface cyclone. Other experiments are conducted to look at the sensitivity to the strength of the upper‐level jet, to the intensity of the low‐level baroclinicity, to the location of the jet exit and finally to the shape, amplitude and location of the low‐level cyclone. The location of the explosive growth stage depends primarily on the position of the low‐frequency jet exit while its intensity and even its existence is strongly sensitive to the low‐level background baroclinicity and to the properties of the incipient surface cyclone itself. Copyright © 2010 Royal Meteorological Society
Enhanced aerobic bioremediation of a gasohol release in a fractured bedrock aquifer
Authors: Heaston Mark S. , Hartig Leslie L. , Robinson Melissa , Woodward David S. 
Published: March 2010

AbstractIn January 2005, a gasoline tanker carrying approximately 8,500 gallons of gasohol (gasoline containing 10 percent ethanol) overturned and caught fire in the front yard of a residence. Emergency response crews responded to the accident, extinguished the fire, and recovered residual gasoline on the ground surface. Soil impacted by the release was then removed and disposed of off‐site and free‐phase gasohol was recovered using a combination of vacuum recovery, pumping, and bailing to the extent practicable. Following free product recovery efforts, a feasibility evaluation was completed to select a technology to address the remaining dissolved‐phase contaminants that resulted in biosparging pilot testing and, ultimately, the installation of a full‐scale biosparging system. The full‐scale system has been operating for approximately 21 months, and contaminant concentrations within the heart of the plume have decreased dramatically over a short period of time—in most cases, to below applicable cleanup standards. Despite the complex hydrogeologic conditions and significant initial concentrations, biosparging has proven to be an effective technology to remediate this gasohol release, and it is anticipated that drinking‐water standards can be achieved following two to three years of biosparging (i.e., an additional 3 to 15 months of operations). © 2010 Wiley Periodicals, Inc.
Closing the mass balance at chlorinated solvent sites: Sources and attenuation processes
Authors: Kamath Roopa , Looney Brian B. , Newell Charles J. , Adamson David T. , Vangelas Karen M. 
Published: March 2010

AbstractUsing detailed mass balance and simple analytical models, a spreadsheet‐based application (BioBalance) was developed to equip decision makers with a predictive tool that can provide a semiquantitative projection of source‐zone concentrations and provide insight into the long‐term behavior of the associated chlorinated solvent plume. The various models were linked in a toolkit in order to predict the composite impacts of alternative source‐zone remediation technologies and downgradient attenuation processes. Key outputs of BioBalance include estimates of maximum plume size, the time frame for plume stabilization, and an assessment of the sustainability of anaerobic natural attenuation processes. The toolkit also provides spatial and temporal projections of integrated contaminant flux and plume centerline concentrations.Results from model runs of the toolkit indicate that, for sites trying to meet traditional, “final” remedial objectives (e.g., two to three orders of magnitude reduction in concentration with restoration to potable limits), “dispersive” mechanisms (e.g., heterogeneous flow and matrix diffusion) can extend remedial time frames and limit the benefits of source remediation in reducing plume sizes. In these cases, the removal of source mass does not result in a corresponding reduction in the time frame for source remediation or plume stabilization. However, this should not discourage practitioners from implementing source‐depletion technologies, since results from the toolkit demonstrate a variety of measurable benefits of source remediation. Model runs suggest that alternative, “intermediate” performance metrics can improve and clarify source remediation objectives and better monitor and evaluate effectiveness. Suggested intermediate performance metrics include reduction in overall concentrations or mass within the plume, reduction of flux moving within a plume, and reduction in the potential for risk to a receptor or migration of a target concentration of contaminant beyond a site boundary.This article describes the development of two key modules of the toolkit as well as illustrates the value of using intermediate performance metrics to evaluate the performance of a source‐remediation technology. © 2010 Wiley Periodicals, Inc.
Applying chemical oxidation technologies at NAPL‐impacted sites to facilitate risk‐based closure
Authors: Blanchard Charles 
Published: March 2010

AbstractIn situ chemical oxidation (ISCO) has found widespread remedial application at sites that lack nonaqueous‐phase liquid (NAPL) or have a relatively small amount of contaminant mass. Historically, its use has been limited at sites with large amounts of NAPL, primarily because of cost considerations. Proper application of ISCO can expand its use at sites with substantial amounts of NAPL—particularly where it is being used to selectively remediate higher toxicity fractions or reduce the mobility of the NAPL itself through artificial weathering. Alone or in conjunction with conventional technologies, chemical oxidation provides a means for reducing the risk associated with NAPL and potentially closing impacted sites without completely removing NAPL. © 2010 Wiley Periodicals, Inc.