bluuebunny/crossref_metadata_2025_split huggingface dataset:
THM analysis of a large‐scale heating test incorporating material fabric changes
Authors: Sánchez Marcelo , Gens Antonio , Olivella Sebastiá 
Published: March 2011

SUMMARYEngineered barriers are basic elements in the design of repositories for the isolation of high‐level radioactive waste. This paper presents the thermo‐hydro‐mechanical (THM) analysis of a clay barrier subjected to heating and hydration. The study focuses on an ongoing large‐scale heating test, at almost full scale, which is being carried out at the CIEMAT laboratory under well‐controlled boundary conditions. The test is intensely instrumented and it has provided the opportunity to study in detail the evolution of the main THM variables over a long period of time. Comprehensive laboratory tests carried out in the context of the FEBEX and NF‐PRO projects have allowed the identification of the model parameters to describe the THM behaviour of the compacted expansive clay. A conventional THM approach that assumes the swelling clay as a single porosity medium has been initially adopted to analyse the evolution of the test. The model was able to predict correctly the global THM behaviour of the clay barrier in the short term (i.e. for times shorter than three years), but some model limitations were detected concerning the prediction of the long‐term hydration rate. An additional analysis of the test has been carried out using a double structure model to describe the actual behaviour of expansive clays. The double structure model explicitly considers the two dominant pore levels that actually exist in the FEBEX bentonite and it is able to account for the evolution of the material fabric. The simulation of the experiment using this enhanced model provides a more satisfactory reproduction of the long‐term experimental results. It also contributes to a better understanding of the observed test behaviour and it provides a physically based explanation for the very slow hydration of the barrier. Copyright © 2011 John Wiley & Sons, Ltd.
MRI evaluation of axonal reorganization after bone marrow stromal cell treatment of traumatic brain injury
Authors: Jiang Quan , Qu Changsheng , Chopp Michael , Ding Guang Liang , Davarani Siamak P. Nejad‐ , Helpern Joseph A. , Jensen Jens H. , Zhang Zheng Gang , Li Lian , Lu Mei , Kaplan David , Hu Jiani , Shen Yimin , Kou Zhifeng , Li Qingjiang , Wang Shiyang , Mahmood Asim 
Published: March 2011

AbstractWe treated traumatic brain injury (TBI) with human bone marrow stromal cells (hMSCs) and evaluated the effect of treatment on white matter reorganization using MRI. We subjected male Wistar rats (n = 17) to controlled cortical impact and either withheld treatment (controls; n = 9) or inserted collagen scaffolds containing hMSCs (n = 8). Six weeks later, the rats were sacrificed and MRI revealed selective migration of grafted neural progenitor cells towards the white matter reorganized boundary of the TBI‐induced lesion. Histology confirmed that the white matter had been reorganized, associated with increased fractional anisotropy (FA; p < 0.01) in the recovery regions relative to the injured core region in both treated and control groups. Treatment with hMSCs increased FA in the recovery regions, lowered T2 in the core region, decreased lesion volume and improved functional recovery relative to untreated controls. Immunoreactive staining showed axonal projections emanating from neurons and extruding from the corpus callosum into the ipsilateral cortex at the boundary of the lesion. Fiber tracking (FT) maps derived from diffusion tensor imaging confirmed the immunohistological data and provided information on axonal rewiring. The apparent kurtosis coefficient (AKC) detected additional axonal remodeling regions with crossing axons, confirmed by immunohistological staining, compared with FA. Our data demonstrate that AKC, FA, FT and T2 can be used to evaluate treatment‐induced white matter recovery, which may facilitate restorative therapy in patients with TBI. Copyright © 2011 John Wiley & Sons, Ltd.
A statistical method for verifying mesh convergence in Monte Carlo simulations with application to fragmentation
Authors: Bishop J. E. , Strack O. E. 
Published: March 2011

AbstractA novel method is presented for assessing the convergence of a sequence of statistical distributions generated by direct Monte Carlo sampling. The primary application is to assess the mesh or grid convergence, and possibly divergence, of stochastic outputs from non‐linear continuum systems. Example systems include those from fluid or solid mechanics, particularly those with instabilities and sensitive dependence on initial conditions or system parameters. The convergence assessment is based on demonstrating empirically that a sequence of cumulative distribution functions converges in the Linfty norm. The effect of finite sample sizes is quantified using confidence levels from the Kolmogorov–Smirnov statistic. The statistical method is independent of the underlying distributions.The statistical method is demonstrated using two examples: (1) the logistic map in the chaotic regime, and (2) a fragmenting ductile ring modeled with an explicit‐dynamics finite element code. In the fragmenting ring example the convergence of the distribution describing neck spacing is investigated. The initial yield strength is treated as a random field. Two different random fields are considered, one with spatial correlation and the other without. Both cases converged, albeit to different distributions. The case with spatial correlation exhibited a significantly higher convergence rate compared with the one without spatial correlation. Copyright © 2011 John Wiley & Sons, Ltd.
A three‐dimensional hybrid meshfree‐Cartesian scheme for fluid–body interaction
Authors: Yu P. , Yeo K. S. , Shyam Sundar D. , Ang S. J. 
Published: March 2011

AbstractA numerical method based on a hybrid meshfree‐Cartesian grid is developed for solving three‐dimensional fluid–solid interaction (FSI) problems involving solid bodies undergoing large motion. The body is discretized and enveloped by a cloud of meshfree nodes. The motion of the body is tracked by convecting the meshfree nodes against a background of Cartesian grid points. Spatial discretization of second‐order accuracy is accomplished by the combination of a generalized finite difference (GFD) method and conventional finite difference (FD) method, which are applied to the meshfree and Cartesian nodes, respectively. Error minimization in GFD is carried out by singular value decomposition. The discretized equations are integrated in time via a second‐order fractional step projection method. A time‐implicit iterative procedure is employed to compute the new/evolving position of the immersed bodies together with the dynamically coupled solution of the flow field. The present method is applied on problems of free falling spheres and tori in quiescent flow and freely rotating spheres in simple shear flow. Good agreement with published results shows the ability of the present hybrid meshfree‐Cartesian grid scheme to achieve good accuracy. An application of the method to the self‐induced propulsion of a deforming fish‐like swimmer further demonstrates the capability and potential of the present approach for solving complex FSI problems in 3D. Copyright © 2011 John Wiley & Sons, Ltd.
A higher order compact finite difference algorithm for solving the incompressible Navier–Stokes equations
Authors: Tian Zhenfu , Liang Xian , Yu Peixiang 
Published: March 2011

AbstractOn the basis of the projection method, a higher order compact finite difference algorithm, which possesses a good spatial behavior, is developed for solving the 2D unsteady incompressible Navier–Stokes equations in primitive variable. The present method is established on a staggered grid system and is at least third‐order accurate in space. A third‐order accurate upwind compact difference approximation is used to discretize the non‐linear convective terms, a fourth‐order symmetrical compact difference approximation is used to discretize the viscous terms, and a fourth‐order compact difference approximation on a cell‐centered mesh is used to discretize the first derivatives in the continuity equation. The pressure Poisson equation is approximated using a fourth‐order compact difference scheme constructed currently on the nine‐point 2D stencil. New fourth‐order compact difference schemes for explicit computing of the pressure gradient are also developed on the nine‐point 2D stencil. For the assessment of the effectiveness and accuracy of the method, particularly its spatial behavior, a problem with analytical solution and another one with a steep gradient are numerically solved. Finally, steady and unsteady solutions for the lid‐driven cavity flow are also used to assess the efficiency of this algorithm. Copyright © 2011 John Wiley & Sons, Ltd.
Modification of novel bio‐based resin‐epoxidized soybean oil by conventional epoxy resin
Authors: Gupta A.P. , Ahmad Sharif , Dev Anshu 
Published: March 2011

AbstractConventional epoxy resin (DGEBA), in varying proportion, was used to modify epoxidized soybean oil (ESO) based systems, crosslinked by phthalic anhydride. The properties of DGEBA modified ESO systems were investigated by dynamic mechanical analysis, impact testing, tensile and flexural testing, scanning electron microscopy, and thermogravimetric analysis. Single loss factor tan δ peak was obtained for all of the modified systems. The results show the improvement in mechanical properties from their high crosslinking densities through the introduction of DGEBA with increase in initial degradation temperature, as obtained from thermogravimetric analysis. Results approaches to an ideal composition which gives the optimum property. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Optimization of powder injection molding of feedstock based on aluminum oxide and multicomponent water‐soluble polymer binder
Authors: Hausnerova Berenika , Marcanikova Lucie , Filip Petr , Saha Petr 
Published: March 2011

AbstractAnalyses crucial to optimize powder injection molding of feedstock based on aluminum oxide powder and multicomponent polymeric binder are provided with the aim to obtain defect‐free, high density parts. As the critical step of the process is the flow of highly filled (60 vol%) compound into a mold cavity, rheological properties supplemented by thermal and pressure‐volume‐temperature characteristics are measured and described. Upon shear deformation the feedstock undergoes structural changes, which are quantified in terms of yield stresses obtained using Herschel‐Bulkley and Casson methods. Further, the rheological model is developed to describe the flow behavior of the feedstock in the whole shear rate range measured. Thermogravimetric analysis is performed to optimize debinding step of the process, and two possible ways of the binder removal are proposed: purely thermal andcombined solvent/thermal. The quality of the final sintered parts is demonstrated on scanning electron microscopic images of their surfaces. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Microstructure, morphology, and mechanical properties of styrene‐butadiene rubber/organoclay nanocomposites
Authors: Díez J. , Barral L. , Bellas R. , Bouza R. , López J. , Marco C. , Ellis G. 
Published: March 2011

AbstractComposites based on styrene‐butadiene rubber containing organophilic montmorillonite were produced by melt compounding and conventional sulfur curing. The samples were characterized by X‐ray diffraction and both transmission and scanning electron microscopy. The dispersion of the clay and the spacing between the silicate layers revealed the presence of intercalated, aggregated, and partially exfoliated structures. Infrared spectroscopy also provided clear evidence for clay exfoliation and migration of zinc stearate to the surface of the samples. The crosslink density, evaluated through swelling in toluene, decreased with increasing organoclay content. This behavior could be justified by the partial absorption of the curatives on the filler surface. The mechanical properties of nanocomposites significantly increased when compared with those of unfilled rubber. These enhanced properties were attributed to the intercalation/exfoliation of the organoclay. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Refractive materials for interlayer optical contacts with TiO2‐based organic/inorganic hybrids
Authors: Okaniwa Kaoru 
Published: March 2011

AbstractOrganic/inorganic hybrid materials were prepared by synthesizing from titanium tetraisopropoxide (TTIP), diethanolamine (DEOA), and water. Formulating the materials with thermosetting polymers, the composites were designed for refractive optical contacts with heat lamination of a film having >50 μm thickness. Inherent difficulties of TiO2 and sol‐gel reaction of TTIP, i.e. photocatalytic properties and prompt sol‐gel reaction to form large TiO2 particle, were avoided by stabilizing Ti with use of DEOA. The reactivity of the sol‐gel reaction and formation of TiO2 crystal structure were suppressed by DEOA. However, suppression of the photocatalytic properties was not enough and needed a use of anti‐oxidant agent, 2,6‐di‐t‐butyl‐p‐cresol (BHT). The titanium‐based organic/inorganic hybrid materials and its epoxy composites were transparent in visible wavelength region and gave in the range of 1.66 to 1.73 of refractive indices depending on stoichometric parameters of TTIP, water, and DEOA for the hybrid materials. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Styrene‐assisted melt‐free radical grafting of glycidyl methacrylate onto isotactic poly(1‐butene)
Authors: Zhou Yanfen , Zhao Yongxian , Yao Wei , Huang Baochen 
Published: March 2011

AbstractThe melt‐free radical grafting of glycidyl methacrylate (GMA) onto powered isotactic poly(1‐butene) (iPB‐1) using styrene (St) as a comonomer in a Haake mixer was studied. The effects of temperature, initial GMA, and peroxide concentration, as well as the addition of St comonomer, on the final grafting degree, grafting efficiency, and the melt flow rate of grafted polymer were studied. It was shown that the addition of St as a comonomer could significantly enhance the grafting degree of GMA on iPB‐1 and reduce the extent of degradation of iPB‐1 to some degree. It has been found that the grafting degree of dual‐monomer melt‐grafted iPB‐1 was about twice that of single‐monomer‐grafted iPB‐1 for the same monomer and peroxide concentrations. The grafting of GMA onto iPB‐1 remarkably accelerated the crystal form II → I transformation of iPB‐1. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Preparation and properties of amphoteric polyacrylamide by seeded dispersion polymerization in ammonium sulfate solution
Authors: Wang Chuanxing , Wang Xiaoxiang , Miao Chunbao , Wu Yumin 
Published: March 2011

AbstractAmphoteric polyacrylamide (AmPAM) was prepared successfully through seeded dispersion polymerization with acrylamide, methacrylatoethyl trimethyl ammonium chloride and acrylic acid as comonomers in ammonium sulfate solution. It was characterized by 1H nuclear magnetic resonance (1H NMR) and elemental analysis. The particle morphology and apparent viscosity of polymer dispersion were obtained by optical microscope and rotary viscometer, respectively. AmPAM dispersion was obtained with low apparent viscosity. The process was smooth without high viscosity stage. The data of 1H NMR spectrum and elemental analysis indicated that all monomers had participated in the polymerization. The seeded reaction time and the mass ratio of two parts of monomers had significant effects on the dispersion polymerization. The best conditions were seeded reaction time 1.75h and the mass ratio 0.75. The apparent viscosity of AmPAM dispersion depended on the number of particles, particle size and low molecular weight polymer concentration in the continuous phase. AmPAM showed both anti‐polyelectrolyte effect and polyelectrolyte effect. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Effect of cyclotrimerization of bisphenol‐A dicyanate monomer on poly(ethylene terephthalate) chain extension
Authors: Zhang Yanjun , Zhang Chen , Li Hangquan , Du Zhongjie 
Published: March 2011

AbstractThe engineering application of poly(ethylene terephthalate) (PET) was limited by its low melt viscosity and strength. Numerous chain extenders were used to enlarge the molecular weight so as to overcome these shortcomings including bisphenol‐A dicyanate (BADCy), which was proven effective in one of our previous work. It was considered that tri‐mer of BADCy through cyclotrimerization might strengthen the effectiveness in chain extender for PET, and the effect of BADCy tri‐mer was studied in this work. With increasing the cyclotrimerization reaction temperature of BADCy monomer, the conversion to tri‐mers was increased. With a fraction of BADCy tri‐mer in the chain extender, the modified PET exhibited higher melt torque, intrinsic viscosity, melt modulus, and melt viscosity than those modified by BADCy monomer alone. BADCy tri‐mer had a positive effect on the chain extension of PET. However, the fraction of tri‐mers in the monomer/tri‐mer mixture should be limited to a certain value; otherwise, the chain extension would be weakened. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Crystallization and morphology studies of biodegradable poly(ϵ‐caprolactone)/polyhedral oligomeric silsesquioxanes nanocomposites
Authors: Pan Hong , Yu Jing , Qiu Zhaobin 
Published: March 2011

AbstractBiodegradable poly(ε‐caprolactone) (PCL)/polyhedral oligomeric silsesquioxanes (POSS) nanocomposites at various POSS loadings were prepared via solution casting method in this work. Scanning electron microscopy observation indicates that POSS are homogeneously dispersed in the PCL matrix. The experiments show that the crystallization peak temperature is higher in the nanocomposites than in neat PCL during nonisothermal melt crystallization; moreover, the overall crystallization rate is faster in the nanocomposites than in neat PCL during isothermal melt crystallization. Both nonisothermal and isothermal melt crystallization studies suggest that the crystallization of PCL is enhanced by the presence of POSS and influenced by the POSS loading. The effect of POSS on the crystallization is twofold: the presence of POSS may provide heterogeneous nucleation sites for the PCL crystallization while the aggregates of POSS may restrict large crystal growth of PCL. However, the crystallization mechanism and crystal structure of PCL remain almost unchanged despite the presence of POSS in the nanocomposites. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Enhanced infrared transmission of GZO film by rapid thermal annealing for Si thin film solar cells
Authors: Jia Haijun , Matsui Takuya , Kondo Michio 
Published: March 2011

ABSTRACTGa doped ZnO (GZO) films prepared by sputtering at room temperature were rapid thermal annealed (RTA) at elevated temperatures. With increasing annealing temperature up to 570°C, film transmission enhanced significantly over wide spectral range especially in infrared region. Hall effect measurements revealed that carrier density decreased from ∼8 × 1020 to ∼ 3 × 1020 cm−3 while carrier mobility increased from ∼15 to ∼28 cm2/Vs after the annealing, and consequently low film resistivity was preserved. Hydrogenated microcrystalline Si (µc‐Si:H) and microcrystalline Si1‐xGex (µc‐Si1‐xGex:H, x = 0.1) thin film solar cells fabricated on textured RTA‐treated GZO substrates demonstrated strong enhancement in short‐circuit current density due to improved spectral response, exhibiting quite high conversion efficiencies of 9.5% and 8.2% for µc‐Si:H and µc‐Si0.9Ge0.1:H solar cells, respectively. Copyright © 2011 John Wiley & Sons, Ltd.
17.9% Metal‐wrap‐through mc‐Si cells resulting in module efficiency of 17.0%
Authors: Lamers M. W. P. E. , Tjengdrawira C. , Koppes M. , Bennett I. J. , Bende E. E. , Visser T. P. , Kossen E. , Brockholz B. , Mewe A. A. , Romijn I. G. , Sauar E. , Carnel L. , Julsrud S. , Naas T. , de Jong P. C. , Weeber A. W. 
Published: March 2011

ABSTRACTWe obtained 17.9% cell efficiency on thin and large mc‐Si REC wafers using ECN's metal‐wrap‐through (MWT) concept. Optimization of several cell processing steps led to an increase of more than 2% absolute in cell efficiency. With these cells 36‐cell modules were manufactured at 100% yield in our industry scale module pilot line. The highest module efficiency obtained (as independently confirmed by JRC‐ESTI) was 17%. In this module the average cell efficiency was 17.8%; this shows a small difference between cell and module efficiency. Copyright © 2011 John Wiley & Sons, Ltd.
Photochemistry of a 6′‐cyanosubstituted spironaphthooxazine: photo‐induced decay of an open form
Authors: Nikolaeva Marina I. , Korolev Valeri V. , Pritchina Elena A. , Glebov Evgeni M. , Plyusnin Victor F. , Metelitsa Anatoly V. , Voloshin Nikolai A. , Minkin Vladimir I. 
Published: March 2011

AbstractPhotochemistry of three 6′‐cyanosubstituted spironaphthooxazines (SNO) in ethanol matrices at 77 K was studied by means of ultraviolet (UV) and erythrocyte sedimentation rate (ESR) spectroscopy and quantum chemistry. The quantum yield of the open form photolysis is found to be 0.01–0.02, which is high enough for 77 K. For one of the SNO, the formation of a merocyanine form radical was observed. The radicals were formed by an H atom abstraction from the solvent molecule to the light‐excited merocyanine isomers. The formation of a merocyanine radical represents a new specific channel of photochemically induced degradation of spirooxazines. Copyright © 2011 John Wiley & Sons, Ltd.
Kinetics and product distribution of p‐nitrophenyl phosphate dianion solvolysis in ternary DMSO/alcohol/water mixtures are compatible with metaphosphate formation
Authors: Lima F. S. , Chaimovich H. , Cuccovia I. M. 
Published: March 2011

AbstractThe rate of solvolysis of p‐nitrophenyl phosphate (PNPP) dianion in DMSO/water strongly decreases by increasing water concentration. Addition of linear alcohols (methanol, propanol, butanol, pentanol, and hexanol) at constant DMSO/water molar ratio produced an even sharper rate decrease. Alkyl phosphate formation, resulting from PNPP solvolysis in ternary DMSO/water/alcohol mixtures, increased with alcohol concentration and was essentially temperature independent. Methanol and hexanol were the poorest nucleophiles under all conditions. Activation energies and enthalpies for solvolysis in ternary mixtures were similar and entropies varied with alcohol concentration. Taken together these results can be best interpreted in terms of a dissociative mechanism with the intervention of metaphosphate. Copyright © 2011 John Wiley & Sons, Ltd.
‘Every Wednesday I Am Happy’: Childhoods in an Irish Asylum Centre
Authors: White Allen 
Published: March 2011

ABSTRACTIn Ireland, asylum seekers are placed into a system of dispersed ‘direct provision’ reception centres across the country. This paper argues that the frequently contradictory and ambiguous positions created for children living within the Irish asylum system reflect the uncertainties and ambiguities surrounding them as immigrants (as part/not part of host societies), children (as child/not adult), and asylum seekers (as separated‐out populations in dispersal centres). Based on research in a specific asylum dispersal centre, this paper will explore the ways in which the spatialities of the children's lives reflect and constitute these contradictions and ambiguities in a host of different ways. Copyright © 2011 John Wiley & Sons, Ltd.