bluuebunny/crossref_metadata_2025_split huggingface dataset:
A stochastic gradual cover location problem
Authors: Drezner Tammy , Drezner Zvi , Goldstein Zvi 
Published: March 2010

AbstractCovering models assume that a point is covered if it is within a certain distance from a facility and not covered beyond that distance. In gradual cover models it is assumed that a point is fully covered within a given distance from a facility, then cover gradually declines, and the point is not covered beyond a larger distance. Gradual cover models address the discontinuity in cover which may not be the correct approach in many situations. In the stochastic gradual cover model presented in this article it is assumed that the short and long distances employed in gradual cover models are random variables. This refinement of gradual cover models provides yet a more realistic depiction of actual behavior in many situations. The maximal cover model based on the new concept is analyzed and the single facility location cover problem in the plane is solved. Computational results illustrating the effectiveness of the solution procedures are presented. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010
Thermodynamically consistent phase‐field models of fracture: Variational principles and multi‐field FE implementations
Authors: Miehe C. , Welschinger F. , Hofacker M. 
Published: March 2010

AbstractThe computational modeling of failure mechanisms in solids due to fracture based on sharp crack discontinuities suffers in situations with complex crack topologies. This can be overcome by a diffusive crack modeling based on the introduction of a crack phase‐field. In this paper, we outline a thermodynamically consistent framework for phase‐field models of crack propagation in elastic solids, develop incremental variational principles and consider their numerical implementations by multi‐field finite element methods. We start our investigation with an intuitive and descriptive derivation of a regularized crack surface functional that Γ‐converges for vanishing length‐scale parameter to a sharp crack topology functional. This functional provides the basis for the definition of suitable convex dissipation functions that govern the evolution of the crack phase‐field. Here, we propose alternative rate‐independent and viscous over‐force models that ensure the local growth of the phase‐field. Next, we define an energy storage function whose positive tensile part degrades with increasing phase‐field. With these constitutive functionals at hand, we derive the coupled balances of quasi‐static stress equilibrium and gradient‐type phase‐field evolution in the solid from the argument of virtual power. Here, we consider a canonical two‐field setting for rate‐independent response and a time‐regularized three‐field formulation with viscous over‐force response. It is then shown that these balances follow as the Euler equations of incremental variational principles that govern the multi‐field problems. These principles make the proposed formulation extremely compact and provide a perfect base for the finite element implementation, including features such as the symmetry of the monolithic tangent matrices. We demonstrate the performance of the proposed phase‐field formulations of fracture by means of representative numerical examples. Copyright © 2010 John Wiley & Sons, Ltd.
Sperm analysis of patients after successful treatment of childhood acute lymphoblastic leukemia with chemotherapy
Authors: Marquis Adine , Kuehni Claudia E. , Strippoli Marie‐Pierre F. , Kühne Thomas , Brazzola Pierluigi 
Published: March 2010

AbstractSurvivors of childhood acute lymphoblastic leukemia (ALL) treated with radiotherapy are at risk for impaired fertility. Whether chemotherapy alone is also long‐term gonadotoxic is unclear. We assessed gonadal function in 11 male ALL‐survivors treated with the same chemotherapy regimen and compared sperm analysis to healthy men. While sex hormone levels were normal in all subjects, 5/11 survivors showed pathological sperm concentration and 4/11 a decreased total sperm count compared to WHO criteria. Compared to healthy controls, all quantitative parameters in semen analysis of survivors were decreased. This suggests that treatment with chemotherapeutic agents alone, even in moderate doses, might have a gonadotoxic effect. Pediatr Blood Cancer 2010;55:208–210. © 2010 Wiley‐Liss, Inc.
Effect of plasma treatment of silk fibroin powder on the properties of silk fibroin powder/polyurethane blend film
Authors: Zhu Lu , Xu Weilin , Ma Mingbo , Zhou Hao 
Published: March 2010

AbstractIn this study, silk fibroin powder was treated by dielectric barrier discharge (DBD) plasma. The objective is to improve the performance of the silk fibroin powder/polyurethane (PU) blend film used in biomechanical field. The scanning electron microscope (SEM) showed that the plasma‐treated powder was broken into small particles and the film from the treated powder became homogeneous and dense. Fourier transform infrared spectroscopy (FTIR) revealed that the hydrophobic groups in silk fibroin powder were oxidized during plasma treatment. Little change in chemical composition was found on the surface of the blend film from plasma‐treated powder. The fracture strain of the blend film from plasma‐treated powder was remarkably raised, whereas its tensile strength was influenced significantly by the plasma treatment conditions. The wet‐out time of the plasma‐treated powder/PU film was shortened considerably. This indicates the improved hydrophilicity of the blend film. In addition, the decreased values of water vapor permeability suggested that the structure of the blend film became dense. This might result from the strong interfacial adhesion between plasma‐treated powder and PU. POLYM. ENG. SCI., 50:1705–1712, 2010. © 2010 Society of Plastics Engineers
Proton conduction in 1H‐1,2,3‐triazole polymers: Imidazole‐like or pyrazole‐like?
Authors: Nagamani Chikkannagari , Versek Craig , Thorn Michael , Tuominen Mark T. , Thayumanavan S. 
Published: March 2010

AbstractProton transport (PT) plays an important role in many biological processes as well as in materials for renewable energy devices. Gaining insights into functional group requirements for PT would aid the design of new materials that provide enhanced proton conduction. In this report, we outline our efforts to understand the most probable proton conduction pathway in 1H‐1,2,3‐triazole systems. In triazole‐based systems, both imidazole‐ and pyrazole‐like pathways are possible. By systematically comparing structurally analogous polymers based on N‐heterocycles and benz‐N‐heterocycles, we find that the imidazole‐like pathway makes a significant contribution to the proton transfer in 1H‐1,2,3‐triazole systems, while the contribution from pyrazole‐like pathway is negligible. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1851–1858, 2010
Iridium complex grafted to 3,6‐carbazole‐alt‐tetraphenylsilane copolymers for blue electrophosphorescence
Authors: Fei Teng , Cheng Gang , Hu Dehua , Dong Wenyue , Lu Ping , Ma Yuguang 
Published: March 2010

AbstractWe designed a 3,6‐dibromo‐9‐hexyl‐9H‐carbazole derivative with the blue emissive iridium complex bis[2‐(4,6‐difluorophenyl)pyridyl‐N,C2′](picolinato)iridium(III) (FIrpic) linked at the alkyl terminal. Based on this monomer, novel 3,6‐carbazole‐alt‐tetraphenylsilane copolymers grafted with FIrpic were synthesized by palladium‐catalyzed Suzuki coupling reaction, and the content of FIrpic in the polymers could be controlled by feed ratio of the monomers. The polymer films mainly show blue emission from FIrpic, and the emission intensity from the polymer backbones is much weaker compared with the doped analogues, which demonstrates an efficient energy transfer from polymeric host to covalently bonded guest. The phase separation in the polymers was suppressed, which can be identified by atomic force microscopy and designed electroluminescent (EL) devices. EL devices based on the polymers exhibited blue phosphorescence from FIrpic. The luminous efficiency of preliminary devices reached 2.3 cd/A, and the efficiency roll‐off at high current densities was suppressed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1859–1865, 2010
Polymethylene‐b‐polystyrene diblock copolymer: Synthesis, property, and application
Authors: Chen Jian‐Zhuang , Zhao Qiao‐Ling , Lu Hui‐Chao , Huang Jin , Cao Shao‐Kui , Ma Zhi 
Published: March 2010

AbstractThe design and synthesis of well‐defined polymethylene‐b‐polystyrene (PM‐b‐PS, Mn = 1.3 × 104–3.0 × 104 g/mol; Mw/Mn (GPC) = 1.08–1.18) diblock copolymers by the combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) was successfully achieved. The 1H NMR spectrum and GPC traces of PM‐b‐PS indicated the successful extension of PS segment on the PM macroinitiator. The micellization behavior of such diblock copolymers in tetrahydrofuran were characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM) techniques. The average aggregate sizes of PM‐b‐PS diblock copolymers with the same length of PM segment in tetrahydrofuran solution (1.0 mg mL−1) increases from 104.2 nm to 167.7 nm when the molecular weight of PS segment increases. The spherical precipitated aggregates of PM‐b‐PS diblock copolymers with an average diameter of 600 nm were observed by AFM. Honeycomb porous films with the average diameter of 3.0 μm and 6.0 μm, respectively, were successfully fabricated using the solution of PM‐b‐PS diblock copolymers in carbon disulfide via the breath‐figure (BF) method under a static humid condition. The cross‐sections of low density polyethylene (LDPE)/polystyrene (PS)/PM‐b‐PS and LDPE/polycarbonate (PC)/PM‐b‐PS blends were observed by scanning electron microscope and reveal that the PM‐b‐PS diblock copolymers are effective compatilizers for LDPE/PS and LDPE/PC blends. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1894–1900, 2010
Synthesis, characterization, and field‐effect transistor performance of poly[2,6‐bis(3‐tridecanoxythiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene]
Authors: Leenen Mark A. M. , Meyer Tim , Cucinotta Fabio , Thiem Heiko , Anselmann Ralf , De Cola Luisa 
Published: March 2010

AbstractA new copolymer of benzo[1,2‐b:4,5‐b′]dithiophene and 3,3′‐bis(tridecanoxy)‐5,5′‐bithiophene was synthesized through Stille copolymerization. The bis‐(3‐alkoxythiophene) monomer was synthesized through a silver fluoride mediated, palladium‐catalyzed cross‐coupling, in which bromide functional groups were preserved instead of consumed. The copolymer has been characterized and applied in field‐effect transistors, giving a hole mobility of 2 × 10−3 cm2/Vs and an on/off ratio >106, with negligible hysteresis, on standard silicon substrates. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1973–1978, 2010
Frontal cationic curing of epoxy resins
Authors: Scognamillo Sergio , Bounds Chris , Luger Michael , Mariani Alberto , Pojman John A. 
Published: March 2010

AbstractWe studied the frontal curing of trimethylolpropane triglycidyl ether (TMPTGE) using two BF3‐amine initiators and two fillers, kaolin and fumed silica. In the case of kaolin, the range of concentrations allowing for frontal polymerization to propagate was dependent on its heat absorption effect whereas in the case of silica it was a consequence of the rheological features of this additive. However, for both systems the velocity and front temperature show the same trends; in all cases front velocities were on the order of 1 cm/min with front temperatures about 200 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2000–2005, 2010
Stimulus‐responsive polymers based on 2‐hydroxypropyl acrylate prepared by RAFT polymerization
Authors: Vo Cong‐Duan , Rosselgong Julien , Armes Steven P. , Tirelli Nicola 
Published: March 2010

AbstractHomopolymerization and diblock copolymerization of 2‐hydroxypropyl acrylate (HPA) has been conducted using reversible addition fragmentation chain transfer (RAFT) chemistry in tert‐butanol at 80 °C. PHPA homopolymers were obtained with high conversions and narrow molecular weight distributions over a wide range of target degrees of polymerization. Like its poly(2‐hydroxyethyl methacrylate) isomer, PHPA homopolymer exhibits inverse temperature solubility in dilute aqueous solution, with cloud points increasing systematically on lowering the mean chain length. The nature of the end groups is shown to significantly affect the cloud point, whereas no effect of concentration was observed over the PHPA concentration range investigated. Various thermoresponsive PHPA‐based diblock copolymers were prepared via one‐pot syntheses in which the second block was either permanently hydrophilic or pH‐responsive. Preliminary studies confirmed that poly(ethylene oxide)‐poly(2‐hydroxypropyl acrylate) (PEO45‐PHPA48) and poly(2‐hydroxypropyl acrylate)‐ poly(2‐hydroxyethyl acrylate) (PHPA49‐PHEA68)diblock copolymers formed well‐defined PHPA‐core micelles in 10 mM sodium nitrate solution at 40 °C and 70 °C with mean hydrodynamic diameters of 20 nm and 35 nm, respectively. In contrast, most other PHPA‐based diblock copolymers investigated formed larger colloidal aggregates in 10 mM NaNO3 solution at elevated temperatures. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2032–2043, 2010
Evaluation of light scattering models to characterize concentrated polymer particles embedded in a solid polymer matrix
Authors: Otero Fernando A. , Frontini Gloria L. , Eliçabe Guillermo E. 
Published: March 2010

AbstractThis work deals with the application of the static light scattering (SLS) model of Vrij (VM) for the characterization of a spherical polydisperse concentrated polymer particle system. This model is the exact solution for the SLS of such mixture of particles in the Percus–Yevick approximation. The analyzed polymer particle samples are obtained by solution polymerization of isobornyl methacrylate in polyisobutylene. At the end of the polymerization, as a result of phase separation, a particle system of micrometer sized particles with a moderate distribution of sizes and a volume fraction between 5 and 10% is formed. The SLS data were also analyzed using the local monodisperse approximation (LMA), a well‐known approximation to the model of Vrij. As expected, the estimations with the VM gave better results than those performed with the LMA model for the parameters related to the shape of the particle size distribution as compared with independent determinations of these quantities obtained from scanning electron microscopy micrographs. However, the main motivation to use the more rigorous model seems to be the fact that the volume fraction of particles can be extracted from the data even when relative SLS measurements are used. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 958–963, 2010
Exchange with temperature of the electron‐vibrational mode interaction between thienylene–phenylene copolymer rings
Authors: Silva R. A. , Cury L. A. , Guimarães P. S. S. , Marletta Alexandre , Serein‐Spirau F. , Bouachrine M. , Moreau J. J. E. , Lère‐Porte J.‐P. 
Published: March 2010

AbstractThienylene–dialkoxyphenylene copolymers with polar side chains are soluble in most organic solvents and exhibit excellent glass adhesion properties, allowing the formation of homogeneous thin films on glass, quartz, and other substrates by spin coating. The electrochemical and optical properties of thin films of this material are studied in this work. The calculated band gap derived from electrochemical data (2.34 eV) is in good agreement with that observed from the UV–vis spectrum edge (2.25 eV). The analysis of the emission properties reveals the strong dependence on temperature of the electron coupling with different vibrational modes in the formation of the vibronic bands. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 964–971, 2010
Crystallization kinetics study of poly(L‐lactic acid)/carbon nanotubes nanocomposites
Authors: Shieh Yeong‐Tarng , Twu Yawo‐Kuo , Su Chean‐Cheng , Lin Rong‐Hsien , Liu Gin‐Lung 
Published: March 2010

AbstractEffects of carbon nanotubes (CNT) on the isothermal crystallization kinetics of poly(L‐lactic acid) (PLLA) were quantitatively investigated using the Avrami equation and the secondary nucleation theory of Lauritzen and Hoffman. CNT via grafting modification with PLLA could well disperse in the PLLA matrix and give significantly enhanced crystallization rate and crystallinity of PLLA as analyzed by differential scanning calorimetry and polarized optical microscopy. Analysis of isothermal crystallization kinetics using the Avrami equation demonstrated that CNT significantly enhanced the bulk crystallization of PLLA. Analysis of spherulite growth kinetics using the secondary nucleation theory of Lauritzen and Hoffman found that CNT could expand the temperature range of the crystallization regime III of PLLA. Values of the nucleation constant (Kg) in crystallization regimes III and II of PLLA both increased with increasing CNT contents. The Kg III/Kg II ratios were found to be close to the theoretical value 2 but were not clearly found to depend on the CNT contents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 983–989, 2010
Dielectric, thermal, and mechanical properties of CeO2‐filled HDPE composites for microwave substrate applications
Authors: Anjana P. S. , Deepu V. , Uma S. , Mohanan P. , Philip J. , Sebastian M. T. 
Published: March 2010

AbstractCerium oxide‐filled high density polyethylene (HDPE) composites for microwave substrate applications were prepared by sigma‐blend technique. The HDPE was used as the matrix and the dispersion of CeO2 in the composite was varied up to 0.5 by volume fraction, and the dielectric properties were studied at 1 MHz and microwave frequencies. The variations of thermal conductivity (keff), coefficient of thermal expansion (αc) and Vicker's microhardness with the volume fraction of the filler were also measured. The relative permittivity (εeff) and dielectric loss (tan δ) were found to increase with increase in CeO2 content. For 0.4 volume fraction loading of the ceramic, the composite had εeff = 5.7, tan δ = 0.0068 (at 7 GHz), keff = 2.6 W/m °C, αc = 98.5 ppm/°C, Vicker's microhardness of 18 kg/mm2 and tensile strength of 14.6 MPa. Different theoretical approaches have been used to predict the effective permittivity, thermal conductivity, and coefficient of thermal expansion of composite systems and the results were compared with the experimental data. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 998–1008, 2010
Time‐resolved photoelectron nano‐spectroscopy of individual silver particles: Perspectives and limitations
Authors: Rohmer Martin , Bauer Michael , Leissner Till , Schneider Christian , Fischer Alexander , Niedner‐Schatteburg Gereon , Issendorff Bernd v. , Aeschlimann Martin 
Published: March 2010

AbstractSimultaneous time‐ and energy‐resolved two‐photon photoemission with nanometer resolution is demonstrated for the first time. We monitor the energy dependence of the decay dynamics of electron excitations in individual silver particles, which were deposited from a gas aggregation cluster source onto a silicon substrate. We show furthermore that the near‐field enhancement due to plasmon‐resonant excitation is an efficient means to address individual nanometer‐sized particles using photoemission electron microscopy.
A flexible class of models for data arising from a ‘thorough QT/QTc study’
Authors: Anand Suraj P. , Ghosh Sujit K. 
Published: March 2010

AbstractThe standard methods for analyzing data arising from a ‘thorough QT/QTc study’ are based on multivariate normal models with common variance structure for both drug and placebo. Such modeling assumptions may be violated and when the sample sizes are small, the statistical inference can be sensitive to such stringent assumptions. This article proposes a flexible class of parametric models to address the above‐mentioned limitations of the currently used models. A Bayesian methodology is used for data analysis and models are compared using the deviance information criteria. Superior performance of the proposed models over the current models is illustrated through a real dataset obtained from a GlaxoSmithKline (GSK) conducted ‘thorough QT/QTc study’. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of component properties and orientation on corrugated container endurance
Authors: Popil Roman E. , Hojjatie Barry 
Published: March 2010

AbstractExperiments are performed to determine the impact of several physical properties on the creep behavior of three different sets of corrugated containers subjected to static loading and a cyclic humidity environment ranging from 50% to 80% relative humidity in a 24 h period. One sample set had basis weights of the fluted medium varied from 68 to 205 g/m2 while keeping the basis weight of the linerboard facings at 205 g/m2. This varied the out‐of‐plane shear rigidity of the single wall board by a factor of three. Another set of corrugated samples investigated effects of lateral or linear corrugating by rotation of either linerboards, fluted medium or both. This equalizes hygroexpansivity and affects lifetime. A third series of boxes had barrier coatings applied to their surfaces to determine the effect on lifetime. Creep and lifetime are determined to be inversely related and a multiple regression model for lifetime was sought based on the data set. Homogenization of the corrugated board properties through either increased medium basis weight or component rotation (lateral or linear corrugating) and application of barrier coating will in general, increase the endurance of edge loaded corrugated board in cyclic humidity. Copyright © 2010 John Wiley & Sons, Ltd.
New tactile sensing system for minimally invasive surgical tumour localization
Authors: Perri M. T. , Trejos A. L. , Naish M. D. , Patel R. V. , Malthaner R. A. 
Published: March 2010

AbstractBackgroundMinimally invasive surgery (MIS) suffers from the inability to directly palpate organs for tumour localization. A tactile sensing system (TSS), consisting of a probe and a visualization interface, was developed to present an active pressure map of the contact surface to locate tumours during MIS.MethodsThe TSS performance was compared to MIS graspers to locate occult 10 mm phantom tumours in ex vivo bovine liver and ex vivo porcine lung. Performance assessment included applied pressure, localization distance and accuracy.ResultsThe TSS realized a relative 71% reduction in maximum applied pressure and a 31% increase in detection accuracy in liver tissue (when compared to MIS graspers) and demonstrated no significant differences in performance when palpating lung tissue.ConclusionsThe TSS may help surgeons to identify occult tumours during surgery by restoring some of the haptic information lost during MIS. Copyright © 2010 John Wiley & Sons, Ltd.