bluuebunny/crossref_metadata_2025_split huggingface dataset:
Micro‐Raman characterization of laser‐induced local thermo‐oxidation of thin chromium films
Authors: Baranov A. V. , Bogdanov K. V. , Fedorov A. V. , Yarchuk M. V. , Ivanov A. I. , Veiko V. P. , Berwick K. 
Published: March 2011

AbstractMicro‐Raman spectroscopy was applied to the characterization of the chemical composition and topography of protective oxide layers formed under atmospheric conditions on the surface of thin chromium films. Strips of the layers were produced by local thermal heating using focused sub‐picosecond pulsed laser radiation. It is shown that a CrO2 layer is initially formed on the chromium surface at low light exposures. Increasing the exposure results in the transformation of the CrO2 layer to Cr2O3. The influence of the etching conditions on the composition and thickness of the oxide layers is investigated. The topography of the CrO2 and Cr2O3 oxide layers in transverse sections of the strips is demonstrated by the Raman mapping. Copyright © 2011 John Wiley & Sons, Ltd.
Determinants of Spending: an Evaluation of Three Major Sporting Events
Authors: Saayman Melville , Saayman Andrea 
Published: March 2011

ABSTRACTSouth Africa plays host to a number of major sporting events that takes place annually such as the Two Oceans Marathon, the Argus Cycle Tour and the Midmar open water mile. This research aims to identify the socio‐economic differences of participants in the events and to determine the key drivers of their spending. Three surveys were conducted at the events during 2008 and 2010. The data analyses include a factor and a regression analyses. The analyses identified the different motives why participation takes place, the socio‐demographic differences between participants and the impact thereof on spending. Copyright © 2011 John Wiley & Sons, Ltd.
Apparent exchange rate mapping with diffusion MRI
Authors: Lasič Samo , Nilsson Markus , Lätt Jimmy , Ståhlberg Freddy , Topgaard Daniel 
Published: March 2011

AbstractWater exchange through the cell membranes is an important feature of cells and tissues. The rate of exchange is determined by factors such as membrane lipid composition and organization, as well as the type and activity of aquaporins. A method for noninvasively estimating the rate of water exchange would be useful for characterizing pathological conditions, e.g., tumors, multiple sclerosis, and ischemic stroke, expected to be associated with a change of the membrane barrier properties. This study describes the filter exchange imaging method for determining the rate of water exchange between sites having different apparent diffusion coefficients. The method is based on the filter‐exchange pulsed gradient spin‐echo NMR spectroscopy experiment, which is here modified to be compatible with the constraints of clinical MR scanners. The data is analyzed using a model‐free approach yielding maps of the apparent exchange rate, here being introduced in analogy with the concept of the apparent diffusion coefficient. Proof‐of‐principle experiments are performed on microimaging and whole‐body clinical scanners using yeast suspension phantoms. The limitations and appropriate experimental conditions are examined. The results demonstrate that filter exchange imaging is a fast and reliable method for characterizing exchange, and that it has the potential to become a powerful diagnostic tool. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
In vivo 31P spectroscopy by fully adiabatic extended image selected in vivo spectroscopy: A comparison between 3 T and 7 T
Authors: Bogner W. , Chmelik M. , Andronesi O. C. , Sorensen A. G. , Trattnig S. , Gruber S. 
Published: March 2011

AbstractAn improved image selected in vivo spectroscopy (ISIS) sequence for localized 31P magnetic resonance spectroscopy at 7 T was developed. To reduce errors in localization accuracy, adiabatic excitation, gradient offset independent adiabatic inversion pulses, and a special extended ISIS ordering scheme were used. The localization accuracy of extended ISIS was investigated in phantoms. The possible spectral quality and reproducibility in vivo was explored in a volunteer (brain, muscle, and liver). A comparison between 3 T and 7 T was performed in five volunteers. Adiabatic extended ISIS provided high spectral quality and accurate localization. The contamination in phantom experiments was only ∼5%, even if a pulse repetition time ∼ 1.2·T1 was chosen to maximize the signal‐to‐noise ratio per unit time. High reproducibility was found in the calf muscle for 2.5 cm isotropic voxels at 7 T. When compared with 3 T, localized 31P magnetic resonance spectroscopy in the human calf muscle at 7 T provided ∼3.2 times higher signal‐to‐noise ratio (as judged from phosphocreatine peak amplitude in frequency domain after matched filtering). At 7 T, extended ISIS allowed the performance of high‐quality localized 31P magnetic resonance spectroscopy in a short measurement time (∼3 to 4 min) and isotropic voxel sizes of ∼2.5 to 3 cm. With such short measurement times, localized 31P magnetic resonance spectroscopy has the potential to be applied not only for clinical research but also for routine clinical practice. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
A uniformly optimal‐order error estimate for a bilinear finite element method for degenerate convection‐diffusion equations
Authors: Jia Jinhong , Lu Tongchao , Wang Kaixin , Wang Hong , Ren Yongqiang 
Published: March 2011

AbstractWe prove an optimal‐order error estimate in a degenerate‐diffusion weighted energy norm for bilinear Galerkin finite element methods for two‐dimensional time‐dependent convection‐diffusion equations with degenerate diffusion. In the estimate, the generic constants depend only on certain Sobolev norms of the true solution but not the lower bound of the diffusion. This estimate, combined with a known stability estimate of the true solution of the governing partial differential equations, yields an optimal‐order estimate of the Galerkin finite element method, in which the generic constants depend only on the Sobolev norms of the initial and right side data. Preliminary numerical experiments were conducted to verify these estimates numerically. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011
Graded mesh refinement and error estimates of higher order for DGFE solutions of elliptic boundary value problems in polygons
Authors: Feistauer Miloslav , Sändig Anna‐Margarete 
Published: March 2011

AbstractError estimates for DGFE solutions are well investigated if one assumes that the exact solution is sufficiently regular. In this article, we consider a Dirichlet and a mixed boundary value problem for a linear elliptic equation in a polygon. It is well known that the first derivatives of the solutions develop singularities near reentrant corner points or points where the boundary conditions change. On the basis of the regularity results formulated in Sobolev–Slobodetskii spaces and weighted spaces of Kondratiev type, we prove error estimates of higher order for DGFE solutions using a suitable graded mesh refinement near boundary singular points. The main tools are as follows: regularity investigation for the exact solution relying on general results for elliptic boundary value problems, error analysis for the interpolation in Sobolev–Slobodetskii spaces, and error estimates for DGFE solutions on special graded refined meshes combined with estimates in weighted Sobolev spaces. Our main result is that there exist a local grading of the mesh and a piecewise interpolation by polynoms of higher degree such that we will get the same order O (hα) of approximation as in the smooth case. © 2011 Wiley Periodicals, Inc. Numer Mehods Partial Differential Eq, 2012
Connections between discontinuous Galerkin and nonconforming finite element methods for the Stokes equations
Authors: Becker Roland , Capatina Daniela , Joie Julie 
Published: March 2011

AbstractWe study a discontinuous Galerkin finite element method (DGFEM) for the Stokes equations with a weak stabilization of the viscous term. We prove that, as the stabilization parameter γ tends to infinity, the solution converges at speed γ−1 to the solution of some stable and well‐known nonconforming finite element methods (NCFEM) for the Stokes equations. In addition, we show that an a posteriori error estimator for the DGFEM‐solution based on the reconstruction of a locally conservative H(div, Ω)‐tensor tends at the same speed to a classical a posteriori error estimator for the NCFEM‐solution. These results can be used to affirm the robustness of the DGFEM‐method and also underline the close relationship between the two approaches. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011
Two‐level discretization of the Navier‐Stokes equations with r‐Laplacian subgridscale viscosity
Authors: Borggaard Jeff , Iliescu Traian , Roop John Paul 
Published: March 2011

AbstractThe r‐Laplacian has played an important role in the development of computationally efficient models for applications, such as numerical simulation of turbulent flows. In this article, we examine two‐level finite element approximation schemes applied to the Navier‐Stokes equations with r‐Laplacian subgridscale viscosity, where r is the order of the power‐law artificial viscosity term. In the two‐level algorithm, the solution to the fully nonlinear coarse mesh problem is utilized in a single‐step linear fine mesh problem. When modeling parameters are chosen appropriately, the error in the two‐level algorithm is comparable to the error in solving the fully nonlinear problem on the fine mesh. We provide rigorous numerical analysis of the two‐level approximation scheme and derive scalings which vary based on the coefficient r, coarse mesh size H, fine mesh size h, and filter radius δ. We also investigate the two‐level algorithm in several computational settings, including the 3D numerical simulation of flow past a backward‐facing step at Reynolds number Re = 5100. In all numerical tests, the two‐level algorithm was proven to achieve the same order of accuracy as the standard one‐level algorithm, at a fraction of the computational cost. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011
Revisiting the risk for aneuploidy in fetuses with isolated pyelectasis
Authors: Carbone Jeanine F. , Tuuli Methodius G. , Dicke Jeffrey M. , Macones George A. , Odibo Anthony O. 
Published: March 2011

AbstractObjectivePrevious studies are contradictory with regard to the association of isolated pyelectasis and aneuploidy. Our objective was to test the hypothesis that isolated pyelectasis is associated with aneuploidy and calculate likelihood ratios using a large ultrasound database.MethodsA retrospective cohort study of pregnancies presenting to our prenatal ultrasound unit at 16 to 22 weeks was conducted. Pyelectasis was defined as fetal renal pelvis> 4 mm in the anterior‐posterior dimension. Fetuses with co‐existing major structural anomalies or markers of aneuploidy were excluded. Association between isolated pyelectasis and aneuploidy was assessed and screening efficiency was evaluated. Results were also stratified by maternal age.ResultsAmong 62 103 patients who had obstetric ultrasounds during the study period, 1055 (1.7%) were diagnosed with isolated pyelectasis. The presence of isolated pyelectasis was significantly associated with any aneuploidy [OR 1.93 (CI 1.06–3.54)], and specifically trisomy 21 (T21) [OR 2.91 (CI 1.48–5.71)]. There was a greater than two‐fold increase in the risk of T21 in the presence of isolated pyelectasis [LR+ 2.44 (CI 1.28–4.64)].ConclusionsOur data confirm a significant association between isolated pyelectasis and increased risk of aneuploidy, particularly T21. These likelihood ratios can be used to adjust aneuploidy risk and in counseling patients regarding appropriateness of amniocentesis. Copyright © 2011 John Wiley & Sons, Ltd.
Effect of molecular structure and rheology on the compression foam molding of ethylene‐α‐olefin copolymers
Authors: Zhang Ying , Kontopoulou Marianna , Ansari Mahmoud , Hatzikiriakos Savvas , Park Chul B. 
Published: March 2011

AbstractThe morphology and mechanical properties of foams made out of a series of ethylene‐α‐olefin copolymers having well‐characterized rheological properties were investigated. A compression foaming molding technique was implemented, using azodicarbonamide as the blowing agent. The polymers differed in the amount of comonomer contained (resulting in a range of densities), type of comonomer (octene vs. butene) and molecular weight, resulting in variable thermal properties and different rheological responses under shear and extensional flow. The results showed that the majority of the octene‐based copolymers with comparable rheological properties had similar foam morphology. A distinct behaviour was observed for the butene‐based copolymer, as well as the octene‐containing one having the lowest density and lowest melting/crystallization points. The poor foamability of these grades was attributed to their differences in extensional and thermal properties, respectively. Increasing density resulted in a higher secant modulus of the foamed samples. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
A proposed technique to improve the filling of the mold cavity by polymer during injection molding
Authors: Hassan Hamdy , Regnier Nicolas , George Jean‐Marie , Defaye Guy , Arquis Eric 
Published: March 2011

AbstractIn this study, a technique is proposed to improve the filling process of the injection molding and minimize the solidification during the filling to achieve a complete filling of the mold cavity. Two methods are proposed: stopping the flow rate of the cooling fluid or passing cooling fluid inside the cooling channels at higher temperature during a period of the injection molding cycle. The configuration studied consists of the mold with cuboids‐shape cavity having two different thicknesses. A validation of the numerical model used by an experimental work is presented. The results show that, stopping of cooling fluid on a period of injection cycle has not great effect on the improvement of injection cycle. The results indicate that passing coolant fluid at higher temperature during the ejection stage decreases the solidification of the polymer during the filling stage by about 40%. © POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.
The influence of DMDBS on the morphology and mechanical properties of polypropylene cast films
Authors: Sreenivas K. , Pol Harshawardhan V. , Kumaraswamy Guruswamy 
Published: March 2011

AbstractWe investigate extrusion film casting (EFC) of polypropylene (PP) and examine the effects of varying the concentration of nucleating agent, dimethyl dibenzylidene sorbitol (DMDBS); melt temperature at the die exit; and the draw ratio. Addition of DMDBS increases the PP crystallization temperature, and consequently the PP lamellar repeat spacing. For the draw ratios explored, we do not observe any substantial orientation of iPP crystals for films of neat iPP. However, addition of DMDBS results in the formation of oriented PP crystals, with greater orientation for higher draw ratios. On cooling from the melt, a network of DMDBS nanofibers forms in the PP. We believe that flow‐alignment of this DMDBS network templates the orientation of PP crystals. We observe that the tensile modulus and yield stress increase with PP crystal orientation. However, at high DMDBS concentrations (0.8%), films have poor mechanical strength due to formation of voids and defects. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Preparation and crystallization behavior of multiwalled carbon nanotubes/poly(vinyl alcohol) nanocomposites
Authors: Zhu Yilei , Du Zhongjie , Li Hangquan , Zhang Chen 
Published: March 2011

AbstractThe poly(vinyl alcohol) (PVA)‐based nanocomposites embedded with modified multiwalled carbon nanotubes (MWCNTs) were prepared. To enhance the interfacial interaction between MWCNTs and PVA, acid‐treated MWCNTs were grafted with PVA chains, compatibilizing MWCNTs and the matrix. The better dispersion of MWCNTs in PVA matrix was obtained by the introduction of MDI reaction bridges and then PVA molecules onto the surface of MWCNTs. Moreover, strong interaction between MWCNTs and PVA matrix was evidenced through the measurement results of the melting behavior, polarized Raman measurement, and nonisothermal crystallization behavior of the nanocomposites. Owing to the reinforcement of MWCNTs, the tensile strength and modulus of PVA nanocomposite containing 0.9 wt% MWCNTs were increased by 160.7 and 109.2%, respectively, compared to neat PVA. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
One‐pot synthesis of polyamide 12,T–polyamide‐6 block copolymers
Authors: Novitsky Theodore F. , Mathias Lon J. 
Published: March 2011

AbstractPolyamide 12,T–polyamide‐6 (PA‐12,T–PA‐6) block copolymers were synthesized by anionic polymerization of caprolactam using a PA‐12,T macrocoinitiator (McI). PA‐12,T McI and its precursors are soluble in molten caprolactam allowing for both the McI step‐growth polymerization and anionic polymerization to be performed in one‐pot. It was found that the competing reaction rates of caprolactam ring‐opening polymerization and McI transamidation are both deterred by a common ion effect using CaCl2 and soluble materials were obtained using >1 mol % CaCl2. Without CaCl2, the reaction mixture solidifies in less than 30 s and produces crosslinked materials. To understand this effect, PA‐12,T McI reactions with caprolactam were performed with 1–10 mol % CaCl2, and polymer structures were characterized using 13C NMR and dilute solution viscometry. These data were then correlated with unique thermal properties and swelling behavior of the block copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Novel suberin‐based biopolyesters: From synthesis to properties
Authors: Sousa Andreia F. , Gandini Alessandro , Silvestre Armando J. D. , Neto Carlos Pascoal , Cruz Pinto José J. C. , Eckerman Christer , Holmbom Bjarne 
Published: March 2011

AbstractThis article reports the successful synthesis and characterization of two types of completely biobased polymers prepared by the polycondensation or polytransesterification of suberin fragments, isolated by different procedures and from two different vegetable sources. These polymerizations were conducted with different experimental conditions in terms of the type of catalyst, the reaction medium and temperature, as well as the molar ratio between the reactive moieties. The ensuing linear or partly crosslinked polyesters were characterized by conventional spectroscopic techniques, SEC, DSC, XRD, DMA, and TGA. These hydrophobic materials represent an original contribution to the growing field of polymers from renewable resources. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Enhancement of OFET performance of semiconducting polymers containing benzodithiophene upon surface treatment with organic silanes
Authors: Sista Prakash , Bhatt Mahesh P. , Mccary Ashton R. , Nguyen Hien , Hao Jing , Biewer Michael C. , Stefan Mihaela C. 
Published: March 2011

AbstractPoly{4,8‐bis(4‐decylphenylethynyl)benzo[1,2‐b:4,5‐b′]dithiophene} (P1) homopolymer and poly{4,8‐bis(4‐decylphenylethynyl)benzo[1,2‐b:4,5‐b′]dithiophene ‐alt‐thiophene} (P2) alternating copolymer have been synthesized by Stille coupling polymerization. The field‐effect mobilities of both polymers were measured on both untreated and silane‐treated OFET devices. Various silanes were selected to allow an incremental increase in the hydrophobicity of the silicon dioxide dielectric. A direct correlation was observed between the hydrophobicity of the silicon dioxide dielectric surface and the enhancement of the field‐effect mobilities. The highest mobilities for both polymers were measured on the OFET devices treated with heptadecafluoro‐1,1,2,2‐tetrahydro‐decyl‐1‐trimethoxysilane (FS) which generated the most hydrophobic surface. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Screening for distress and depression in cancer settings: 10 lessons from 40 years of primary‐care research
Authors: Mitchell Alex J. , Vahabzadeh Arshya , Magruder Kathryn 
Published: March 2011

AbstractObjective: There has been at least 40 years of active research on screening for depression and distress in primary care. Both successes and failures have been documented. The purpose of this focussed narrative review was to summarise this research and present the key lessons for clinicians and researchers working in psychosocial oncology.Methods: We searched for studies assessing the utility of screening in primary care in seven electronic bibliographic databases (CENTRAL, CINAHL, Embase, HMIC, Medline, PsycINFO, Web of Knowledge) from inception to December 2010. Results were reviewed and summarised into key areas.Results: We found that research could be distilled into the following key learning points. (1) Primary care is an important partner in psychosocial care. (2) Both over and under detection are problematic. (3) Barriers to identification involve patient and clinician factors. (4) Acceptability of screening is critical to implementation. (5) Underserved groups need special attention in screening. (6) Patient–clinician trust is an important modifiable variable. (7) Greater contact influences detection. (8) Clinician confidence/skills influence screening success and subsequent action. (9) Training may improve confidence but effects upon long‐term outcomes are modest. (10) Screening is generally ineffective without aftercare.Conclusions: Primary care has shown largely what does not work in relation to screening. Namely relying on clinicians' unassisted judgement without infrastructural support, using over‐complex scales with low acceptability, looking for depression alone, using screening without linked treatment, treating in the absence of follow‐up and failing to engage patients in their own care. These pitfalls can and should be avoided in psychosocial oncology. Copyright © 2011 John Wiley & Sons, Ltd.
Heterotic orbifold resolutions as (2,0) gauged linear sigma models
Authors: Groot Nibbelink S. 
Published: March 2011

AbstractIn this work we attempt to bridge the gap between heterotic orbifold models and Calabi‐Yau compactifications using gauged linear sigma models (GLSMs) with (2,0) worldsheet supersymmetry. We associate a specific GLSM to a heterotic orbifold model with twisted states that have non‐vanishing vacuum expectation values (VEVs): The charges of the GLSM superfields are essentially determined by the shifted momenta of these states. When a twisted state contains an oscillator excitation, a fermionic gauging is introduced on the worldsheet, inducing a non‐Abelian gauge bundle, e.g. the standard embedding. However, irrespectively of whether the twisted states contain oscillators or not, they can be interpreted as blow‐up modes, as their VEVs are correlated with sizes of exceptional cycles in the resolved geometry. We show that the GLSM anomaly cancellation conditions ensure that the Bianchi identities are fulfilled for all possible triangulations of a resolution. By considering marginal deformations of a GLSM in the large volume limit we are able to directly determine its effective four dimensional spectrum. In the cases considered the spectra coincide with those computed via index theorems.