bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variational time integrators for finite‐dimensional thermo‐elasto‐dynamics without heat conduction
Authors: Mata Pablo , Lew Adrián J. 
Published: March 2011

AbstractThis paper focuses on the formulation of variational integrators (VIs) for finite‐dimensional thermo‐elastic systems without heat conduction. The dynamics of these systems happen to have a Hamiltonian structure, after thermal displacements are introduced. It is then possible to formulate integrators by taking advantage of standard methods in VI. The class of integrators we construct have some remarkable features: (a) they are symplectic, (b) they exactly conserve the entropy of the system, or in other words, they exactly satisfy the second law of the thermodynamics for reversible adiabatic processes, (c) they nearly exactly conserve the value of the energy for very long times and (d) they exactly conserve linear and angular momentum. We first describe how to adapt any VI for the classical mechanical systems to integrate adiabatic thermo‐elastic ones, and then formulate three new types of integrators. The first class, based on a generalized trapezoidal rule, gives rise to two first order, explicit integrators, and a second order, implicit one. By composing then the two first‐order integrators we construct a second order, explicit one. Finally, we formulate a fourth order, implicit integrator, which is a symplectic partitioned Runge–Kutta method. The performance of these new algorithms is showcased through numerical examples. Copyright © 2011 John Wiley & Sons, Ltd.
Cholinesterase inhibitor use in Alzheimer's disease: the EPIFARM‐Elderly Project
Authors: Franchi Carlotta , Lucca Ugo , Tettamanti Mauro , Riva Emma , Fortino Ida , Bortolotti Angela , Merlino Luca , Pasina Luca , Nobili Alessandro 
Published: March 2011

ABSTRACTPurposeThis study was designed to examine the prevalence of cholinesterase inhibitor (ChEI) use and the proportions of patients treated with ChEIs by using an administrative prescription database of prevalent and incident cases of mild to moderate Alzheimer's disease (AD) in relation to age and duration of therapy.MethodsA prospective observational study covering individuals aged 65 years or older who received at least one prescription of ChEIs between 1 January 2002 and 31 December 2007 was conducted in three health administrative areas in the Lombardy Region, Italy.ResultsThe prevalence of those who received at least one prescription for ChEIs rose from 0.5% in 2002 to 0.7% in 2004, reaching a plateau. Among estimated prevalent cases of mild to moderate AD, the prevalence of patients who received at least one prescription of ChEIs varied in different age groups, rising in those over 80 years and falling slightly in those under 80 years, particularly in patients aged 65–69 years (test for trend, p < 0.001). Among estimated incident cases, the percentage of newly treated patients dropped from 12% in 2004 to 8% in 2007, as well as within each age group (test for trend, p < 0.001). In the cohort of incident users, nearly 40% of patients who started treatment in 2004 were still in treatment 3 years later.ConclusionsThe prescription prevalence of ChEIs increased up to 2004, then reached a plateau. This might reflect the practical response of physicians and patients to the controversy and uncertainty surrounding the clinical value of these expensive drugs for the treatment of AD. Copyright © 2011 John Wiley & Sons, Ltd.
Solid‐phase extrusion of polyamide‐6 by using combined deformation schemes
Authors: Beloshenko V.A. , Varyukhin V.N. , Voznyak A.V. , Voznyak Yu.V. 
Published: March 2011

AbstractPotentialities of new combined deformation schemes, including the solid state extrusion through conical die (ED) and equal‐channel multiple angle extrusion (ECMAE) implemented in different sequence to modify structure and properties of semicrystalline polymers, have been studied for polyamide‐6 as an example. It is shown that deformation by the ED‐ECMAE scheme gives the best complex of physical and mechanical properties. A significant improvement in elastic and strength properties of polyamide‐6 with the conserved high level of plastic characteristics has been observed. There was only a slight anisotropy and dispersion of microhardness across the extrudates. A more uniform oriented structure with lamellae orientation along extrudate's axis has been formed in semicrystalline polymer because the ED‐ECMAE scheme implementation. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Biaxial stretching of polymers using a novel and versatile stretching system
Authors: Qaiss A. , Bousmina M. 
Published: March 2011

AbstractA novel versatile biaxial stretching module that can be adapted to any uniaxial traction testing machine was developed to generate consecutive or simultaneous two‐directional biaxial stretching at various stretching ratios and draw rates. The module allows direct conversion of the uniaxial machine displacement to transverse displacement with a precise adjustment of the stretch ratio between the transverse of the longitudinal strains. Additionally, the developed device allows simultaneous measurements of films mechanical properties in the two directions. The efficiency and the accuracy of the module were verified without and with standard polymer films such as polypropylene and high density polyethylene. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Stabilizations of molecular structures and mechanical properties of PVC and wood/PVC composites by Tinuvin and TiO2 stabilizers
Authors: Chaochanchaikul Kantima , Sombatsompop Narongrit 
Published: March 2011

AbstractThree different UV stabilizers, 2‐(2H‐benzotriazol‐2‐yl)‐4,6‐ditertpentylphenol (Tinuvin XT833), 2‐(2H‐benzotriazol‐2‐yl)‐p‐cresol (Tinuvin P), or rutile–titanium dioxide (TiO2) were incorporated into poly(vinyl chloride) (PVC) and wood/PVC (WPVC) composite, and mechanical and physical properties and photostabilities were monitored. The polyene and carbonyl sequences of PVC increased with UV weathering time and with presence of wood flour. The yellowness index increased because of polyene and carbonyl productions, whereas the brightness increased because of the photobleaching of lignin in wood. The photostabilities of PVC and WPVC could be improved through the use of UV stabilizers. Tinuvin P was recommended in this work as the most effective stabilizer for PVC and WPVC composites. The stabilization effect was interfered by presence of wood particles. The mechanical property changes corresponded well to the structural changes under UV for neat PVC. For WPVC composites, the presence of wood particles played more significant effect on the mechanical properties during UV aging than the UV stabilizer. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Long‐term mechanical behavior of aramid fibers in seawater
Authors: Derombise G. , Chailleux E. , Forest B. , Riou L. , Lacotte N. , Vouyovitch Van Schoors L. , Davies P. 
Published: March 2011

AbstractAramid fibers are today proposed in ropes and cables for marine applications. As these highly crystalline materials are loaded in tension for a longer period in seawater, their long‐term mechanical behavior has to be understood. However, the response is time‐dependent and exhibits a nonlinear effect with stress. In this study, two types of aramid fibers are studied: Twaron and Technora. Mechanical properties are measured using static tensile tests and creep‐recovery tests. A nonlinear viscoelastic–viscoplastic model, based on the Schapery formulation, allows discriminating between the instantaneous and the time‐dependent response as well as the reversible and nonreversible phenomena (plasticity). First, this procedure allows the overall mechanical behavior of the fibers to be compared, considering creep rate, plasticity, and instantaneous moduli. Then, using these parameters, the effect of the testing condition, air or seawater is studied. Finally, the effect of aging in seawater is quantified for both fibers. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Experimental study on gap bridging in contour laser transmission welding of polycarbonate and polyamide
Authors: Chen Mingliang , Zak Gene , Bates Philip J. , Baylis Bobbye , McLeod Martin 
Published: March 2011

AbstractLaser transmission welding (LTW) is a technique for joining thermoplastics. During contour LTW, any gaps or spaces between the two parts along the weld seam may prevent a weld from forming. This work presents an experimental study on the effects of material property (carbon black level, glass fibers, and crystallinity), process parameters (laser scan power and scan speed), and weld gap thickness on the strength and microstructure of contour welds made of polycarbonate (PC), polyamide 6 (PA6), and PA6 reinforced with 30% glass fiber. Lap specimens, with weld lines parallel to the load direction during mechanical testing, were used to assess the weld shear strength. The results indicated that low concentrations of laser absorbing pigment accompanied by high laser power improve gap bridging. The study also indicated that a novel noncontact test method can be used to search for the optimized process parameters for gap bridging. The maximum gaps bridged were 0.2, 0.4, and 0.25 mm for PC, PA6, and reinforced polyamide 6, respectively. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Tandem cationic and sol–gel photopolymerizations of a vinyl ether alkoxysilane
Authors: Chemtob Abraham , Belon Cindy , Croutxé‐Barghorn Céline , Rigolet Séverinne , Vidal Loïc , Brendlé Jocelyne , Mandel Jérémie , Blanchard Nicolas 
Published: March 2011

AbstractIn the present study, a novel single hybrid monomer combining a vinylether and trimethoxysilane groups in the same molecule was synthesized by chemoselective hydrosilation and subjected to UV‐irradiation in the presence of a triarylsulfonium salt. Through the UV‐decomposition of this photoacid generator, two acid‐catalyzed processes occurred simultaneously: the cationic polymerization of the vinyl ether functions and the sol–gel polycondensation of the alkoxysilyl groups, leading to a type II polyvinyl‐polysilicate nanocomposite film. Both reaction kinetics were efficiently monitored by real‐time Fourier transform infrared spectroscopy, and the influence of different key experimental parameters was investigated (laminated conditions, UV irradiation equipment, and film thickness). A particular attention was also given to the complete characterization of the hybrid microstructure by associating 29Si and 13C solid‐state NMR. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Synthesis, self‐assembly behavior, and biological application of a new photochromic azo amphiphilic diblock copolymer
Authors: Ding Han , Wang Zheng , Sheng Lijiao , Song Gongwu 
Published: March 2011

AbstractPolymer (N,N‐dimethyl‐ethylamine methacrylate)‐block‐poly{6‐[4‐(4‐methoxy phenyl‐azo) phenoxy] hexylacrylate} p(DMAEMA
m‐b‐AZOM
n) was synthesized by successive reversible addition‐fragmentation chain transfer polymerization in the hydrothermal reactor. The products were characterized by hydrogen nuclear magnetic resonance, differential scanning calorimetry, gel permeation chromatography, and ultraviolet and visible absorption spectroscopy (UV‐vis). In H2O/THF mixture, we found amphiphilic p(DMAEMA
m‐b‐AZOM
n) self‐assembles occurred. p(DMAEMA79‐b‐AZOM7) self‐assembled into rods, p(DMAEMA79‐b‐AZOM5) self‐assembled into giant microspheres with rods wind around, p(DMAEMA79‐b‐AZOM2) self‐assembled into microspheres. Photochromic behaviors of the polymers in different environments were investigated. We found the colors of diblock copolymers in films changed from yellow to orange after irradiation by ultraviolet and visible (UV) light. The rates of trans‐cis photoisomerization in films were almost the same for the three p(DMAEMA
m‐b‐AZOM
n) copolymers. The rates in aqueous micellar solutions were only marginally faster than those in films for all the three diblock copolymers. The observation of a sizable rate difference in different environments for p(DMAEMA
m‐b‐AZOM
n) suggested that a rotational mechanism might be operative for these water‐soluble amphiphilic diblock copolymers. The self‐assembly behaviors of three copolymers and the application of p(DMAEMA79‐b‐AZOM2) microspheres in biochemistry were investigated in present work. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Montmorillonite clay nanocomposites based on vinyl pyridine‐styrene‐butadiene terpolymer (VPR)/acrylonitrile‐butadiene rubber (NBR) blend
Authors: Chakraborty Sugata , Kar Saptarshi , Dasgupta Saikat , Mukhopadhyay Rabindra , Chauhan Narendra P.S. , Ameta Suresh C. , Bandyopadhyay Samar 
Published: March 2011

AbstractThis study describes a novel route to synthesize vinyl pyridine‐styrene‐butadiene terpolymer rubber (VP rubber) montmorillonite clay nanocomposites by latex blending technique. The pyridine moiety of the VP rubber was modified with methyl iodide to form the pyridinium ion during latex blending. Cation exchange reaction of the pyridinium ion of the VP rubber latex with sodium montmorillonite occurred during latex stage mixing which helped to form VP rubber‐montmorillonite clay nanocomposites. Coagulation of the latex‐clay slurry produced nanocomposites master batch. The master batch was compounded with acrylonitrile butadiene rubber (NBR). Fourier Transform Infrared Spectroscopy (FTIR) confirmed the modification of the pyridine moiety of VP rubber. Wide angle X‐ray diffraction (WAXD), scanning electron microscopy‐energy dispersive X‐ray spectrophotometry (SEM‐EDS) and transmission electron microscopy (TEM) provided the evidences of formation of nanocomposite. Remarkable improvements in the mechanical properties were found by addition of small amount of modified clay. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Control of the migration behavior of slip agents in polyolefin‐based films
Authors: Llop Cosme , Manrique Antonio , Navarro Rodrigo , Mijangos Carmen , Reinecke Helmut 
Published: March 2011

AbstractUnsaturated long‐chain carboxylic acid amides like Erucamide are very efficient as slipping agents in polyolefin films and other polymers. A problem is the uncontrolled migration of this additive. The main goal of the present project was therefore the study and understanding of Erucamide diffusion through the film and how the diffusion behavior can be altered using plasma surface treatments or additional additives with varying molecular weights and hydrophilic–hydrophobic balance. The determination of the amount of Erucamide and co‐additive at the surface of the polymer film has been carried out by attenuated total reflectance (ATR) spectroscopy. The study shows that the system is highly sensible to the chemical structure of the surface modifier and particularly their hydrophilic–hydrophobic balance and their molecular weight. The most efficient surface modifier tested in this work was a block‐co‐oligomer with 50% polyethylene (PE) and 50% polyethylene oxide (PEO) sequences that can successfully be used to reduce Erucamide migration at both sides of the three‐layer‐PE‐films. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Fabrication of nano/microfiber scaffolds using a combination of rapid prototyping and electrospinning systems
Authors: Park Su A. , Kim Hyo Joo , Lee Su Hee , Lee Jun Hee , Kim Hyung Keun , Yoon Taek Rim , Kim WanDoo 
Published: March 2011

AbstractTissue‐engineered scaffolds require an adequate three‐dimensional (3‐D) structure for cell growth and attachment. Solid freeform fabrication can provide the interconnected pore to induce the cell ingrowth, and electrospinning technique can make the nanofiber web with high surface for cell attachment. In this study, 3‐D polycaprolactone (PCL) scaffolds were fabricated using a rapid prototyping plotting system coupled with an electrospinning apparatus. Scanning electron micrographs showed that these hybrid scaffolds had a regular microfiber structure with interconnected pores and a nanofiber distribution appropriate for cell attachment. Scaffolds were seeded with MG63 cells for in vitro study and implanted in the tibia of rabbit for in vivo study. The resulting structure also facilitated cell adhesion, proliferation, and differentiation as evidenced by biochemical analyses and confocal microscopy. The hybrid scaffolds also exhibited good biocompatibility and osteoconductivity in animal studies. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Silane gas venting/treatment lessons learned and best practices
Authors: VanOmmeren James 
Published: March 2011

AbstractSilane (SiH4) is a pyrophoric gas that requires special equipment and handling precautions to manage safely. Unfortunately, many users have had various serious accidents with SiH4 equipment since popular inception of the gas in the late 1960s for semiconductor manufacture, including at least eight fatalities and many injuries. SiH4 usage is growing tremendously worldwide in various industries, including semiconductor, flat‐panel display, photovoltaic cell, and specialty glass manufacturing. Significant uses of SiH4 also require systems with the capability to safely vent or treat SiH4 gas—such as residual venting during container changes or emergency venting. Six hazards associated with venting and treating SiH4 gas are presented in detail. Each hazard is illustrated by an actual venting incident and resulting lessons learned are discussed. Preferred venting and treatment solutions are detailed and a silane disposal system design work process is presented. Although the article is specific to pure SiH4, it has relevance to both venting and treatment of pyrophoric gases and flammable gases that possess relatively low‐ignition energies. © 2011 American Institute of Chemical Engineers Process Saf Prog 2011
Tensor‐resolved stress analysis in silicon MEMS device by polarized Raman spectroscopy
Authors: Miyatake Takahiro , Pezzotti Giuseppe 
Published: March 2011

AbstractA polarized Raman method is described to measure the tensor elements of the residual stress state (induced upon fabrication) in a thin silicon plate, a suspended structure belonging to the test element group (TEG) chip of a microelectromechanical system (MEMS). The residual stress data experimentally retrieved by the Raman methodology are compared to those calculated according to a finite element model (FEM) of the MEMS. While FEM required the input of the thermal history experienced by the suspended bridge silicon structure, experimental Raman data directly revealed the stress tensor components without any assumption needed. An improved analytical procedure is shown that enables retrieving individual stress tensor components from polarized Raman light. Tensor‐resolved Raman analysis, capable of de‐coupling the hydrostatic and the deviatoric parts of the stress tensor, represents a key‐point in rationalizing the role of thermal history as well as of other processing parameters on the development of internal stress in MEMS devices made of silicon.
Growth and magnetic properties of bulk electron doped La0.7Ce0.3MnO3 manganites
Authors: Sergeenkov S. , Cardoso C. A. , Andreeta M. R. B. , Hernandes A. C. , Leite E. R. , Moreira F. M. Araújo‐ 
Published: March 2011

AbstractWe report on the growth of bulk samples (composite fibers) of the nominal composition La0.7Ce0.3MnO3 (LCMO) manganites (with Curie temperature TC,max = 300 K) by using the laser heated pedestal growth (LHPG) technique. Samples composition was verified through scanning electron microscopy with energy dispersive X‐ray (EDX) analysis. The magnetic behavior of the fibers was probed by magnetization measurements. In addition to a weak ferromagnetic transition at TC0 = 45 K (due to MnO2 impurities), two more transitions with TC1 = 126 K and TC2 = 180 K were identified and linked to regions with cerium concentration of x = 0.063 and 0.13, respectively.
Effects of dopants on the synthesis of Pb(Mg1/3Nb2/3)O3‐PbTiO3 ceramics by the reaction‐sintering method
Authors: Fang Bijun , Ding Chenlu , Wu Jian , Du Qingbo , Ding Jianning 
Published: March 2011

AbstractSintering aid‐doped 0.8Pb(Mg1/3Nb2/3)O3‐0.2PbTiO3 (0.8PMN‐0.2PT) relaxor‐based ferroelectric ceramics were prepared by the reaction‐sintering method. X‐ray diffraction (XRD) measurement, SEM observation, and density measurement confirmed that the Li2CO3‐ and CuO‐doped 0.8PMN‐0.2PT ceramics exhibit pure rhombohedral perovskite structure, rather homogenous micromorphology and high relative density. As compared to the undoped 0.8PMN‐0.2PT ceramics, the Li2CO3‐ and CuO‐doped 0.8PMN‐0.2PT ceramics exhibit enhanced dielectric diffused and frequency dispersion, improved ferroelectric property, and piezoelectric property, while as the sintering temperature is decreased greatly. Therefore, Li2CO3 and CuO are effective sintering aids for the PMN‐PT ceramics prepared by the reaction‐sintering method, which exhibit promising applications in the electronic ceramic industries.
Luminescent properties of tris(2,2′‐bipyridine) dichloro ruthenium(II) hexahydrate under high pressure
Authors: Wang Z. P. , Zhang Z. M. , Zhang J. W. , Sun X. , Ding Z. J. 
Published: March 2011

AbstractThe luminescence properties of tris(2,2′‐bipyridine) dichloro ruthenium(II) hexahydrate ([Ru(bpy)3]2+ Cl2·6H2O) were studied with a diamond anvil cell (DAC) under quasi‐hydrostatic pressure. The emission intensity increases with elevated pressure and the fluorescence maxima was observed at 1.7 GPa. The emission intensity then drops down with further compression. The emission peak position shift to higher energy side (blue shift) firstly, and then shift to lower energies (red shift) at pressures above 1.4 GPa. Two phase transitions occur at about 1.4 and 6.6 GPa. The emission almost quench at 10.4 GPa. This behavior may be due to the reduction of Ru ion coordination number; the 2,2′‐bipyridine molecules are isolated from [Ru(bpy)3]2+ and thus influence the emission properties.
Fixed‐wing attitude estimation using temporal tracking of the horizon and optical flow
Authors: Dusha Damien , Mejias Luis , Walker Rodney 
Published: March 2011

AbstractA method has been developed for estimating pitch angle, roll angle, and aircraft body rates based on horizon detection and temporal tracking using a forward‐looking camera, without assistance from other sensors. Using an image processing front end, we select several lines in an image that may or may not correspond to the true horizon. The optical flow at each candidate line is calculated, which may be used to measure the body rates of the aircraft. Using an extended Kalman filter (EKF), the aircraft state is propagated using a motion model and a candidate horizon line is associated using a statistical test based on the optical flow measurements and the location of the horizon. Once associated, the selected horizon line, along with the associated optical flow, is used as a measurement to the EKF. To test the accuracy of the algorithm, two flights were conducted, one using a highly dynamic uninhabited airborne vehicle (UAV) in clear flight conditions and the other in a human‐piloted Cessna 172 in conditions in which the horizon was partially obscured by terrain, haze, and smoke. The UAV flight resulted in pitch and roll error standard deviations of 0.42 and 0.71 deg, respectively, when compared with a truth attitude source. The Cessna flight resulted in pitch and roll error standard deviations of 1.79 and 1.75 deg, respectively. The benefits of selecting and tracking the horizon using a motion model and optical flow rather than naively relying on the image processing front end are demonstrated. © 2011 Wiley Periodicals, Inc.