bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flavone potently stimulates an apical transporter for flavonoids in human intestinal Caco‐2 cells
Authors: Lies Barbara , Martens Stefan , Schmidt Sabine , Boll Michael , Wenzel Uwe 
Published: September 2012

ScopeBased on the studies suggesting that active transport mechanisms contribute to the absorption of flavonoids into human intestinal Caco‐2 cells, we here used the structurally similar fluorescent rhodamine 123 to test a possible influence of flavonoids on its uptake.Methods and resultsRhodamine absorption displayed saturation kinetics with a Km of 1.1 μM and a pH‐optimum of 8.5 and was stimulated by flavone four‐fold in its Vmax. Ring C of the other 16 flavonoids tested turned out to be of special importance in order to act as potent inhibitors for rhodamine transport, with a positive charge there, as present in the anthocyanidins, or a 2,3 double bond together with an aromatic ring fused to position 2, as present in flavones and flavonols, being essential structural requirements. Flavone‐stimulated rhodamine uptake was unaffected by classical substrates of organic cation transporters or inhibitors of adenosine triphosphate (ATP)‐dependent efflux pumps. Also, inhibitors of mitogen‐activated protein kinases or tyrosine kinases did not influence the transport, whose stimulation, however, was essentially dependent on the simultaneous presence of flavone. The existence of a flavone‐activated apical flavonoid transporter in Caco‐2 cells was finally associated with the potently diminished transepithelial apical to basolateral fluxes of 14C‐kaempferol in the presence of competing unlabeled flavonoid substrates.ConclusionIn conclusion, flavone activates an as yet unidentified transporter for flavonoids in the apical membrane of Caco‐2 cells.
An immersed boundary element method for level‐set based topology optimization
Authors: Yamasaki Shintaro , Yamada Takayuki , Matsumoto Toshiro 
Published: September 2012

SUMMARYIn this paper, we propose a new BEM for level‐set based topology optimization. In the proposed BEM, the nodal coordinates of the boundary element are replaced with the nodal level‐set function and the nodal coordinates of the Eulerian mesh that maintains the level‐set function. Because this replacement causes the nodal coordinates of the boundary element to disappear, the boundary element mesh appears to be immersed in the Eulerian mesh. Therefore, we call the proposed BEM an immersed BEM. The relationship between the nodal coordinates of the boundary element and the nodal level‐set function of the Eulerian mesh is clearly represented, and therefore, the sensitivities with respect to the nodal level‐set function are strictly derived in the immersed BEM. Furthermore, the immersed BEM completely eliminates grayscale elements that are known to cause numerical difficulties in topology optimization. By using the immersed BEM, we construct a concrete topology optimization method for solving the minimum compliance problem. We provide some numerical examples and discuss the usefulness of the constructed optimization method on the basis of the obtained results. Copyright © 2012 John Wiley & Sons, Ltd.
Novel conjugated polymer/graphene/platinum composite for enhancing electrocatalytic oxidation of methanol
Authors: He Mingping , Zheng Yuying , Du Qifeng 
Published: September 2012

AbstractA novel conjugated polymer containing electron transport groups with high electron affinity, denoted POXD was synthesized upon polycondensation. The polymer was characterized by Fourier transform infrared (FTIR) spectra and 1H nuclear magnetic resonance (1H NMR) spectroscopy. Furthermore, the conjugated polymer/graphene (POXD/RGO) composite film was prepared, which was subsequently used as the support for the electrodeposition of platinum. The microstructure and morphology of the prepared samples were characterized by X‐ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE‐SEM). The electrocatalytic activity for the oxidation of methanol was investigated through cyclic voltammogram method. The POXD/RGO composite film can facilitate the electrodeposition of Pt nanoparticles compared with graphene (RGO) support. The POXD/RGO/Pt composite exhibits more excellent electrocatalytic property for the oxidation of methanol, such as lower oxidation potential and higher current intensity, which might be attributed to the high electron affinity of the polymer and the interaction of the Pt nanoparticles with polymer. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Production and characterization of UHMWPE/fumed silica nanocomposites
Authors: Ramazani Ahmad , Saremi Maysam Ghahri , Amoli Behnam Neschi , Izadi Hadi 
Published: September 2012

AbstractUltrahigh‐molecular‐weight polyethylene (UHMWPE)/fumed silica nanocomposites were prepared via in situ polymerization using a bi‐supported Ziegler‐Natta catalytic system. Nanocomposites with different nanoparticle weight fractions were produced in order to investigate the effect of fumed silica on thermal and mechanical properties of UHMWPE/fumed silica nanocomposites. The viscosity average molecular weight (M) of all samples including pure UHMWPE as the reference sample and nanocomposites were measured. Scanning electron microscope (SEM) images showed the homogenous dispersion of nanoparticles throughout the UHMWPE matrix while no nanoparticle cluster has been formed. Crystallization behavior of nanocomposites was investigated by differential scanning calorimetry (DSC), which showed a slight increase in melting temperature by enhancing the nanoparticle concentration while no significant change was observed in the crystallization temperature as the fumed silica concentration enhanced. The improvement in all thermal stability parameters was recorded by thermogravimetric analysis (TGA). Besides, via tensile testing, it was confirmed that addition of nanoparticles caused considerable improvement in such mechanical properties as Young's modulus, yield stress, and tensile strength of samples while the elongation at break declined by addition of more nanoparticles. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Side‐chain liquid‐crystalline polymers based on flexible rod‐like mesogen directly attached to backbone
Authors: Zheng Jun‐Feng , Yu Zhen‐Qiang , Liu Xin , Chen Xiao‐Fang , Yang Shuang , Chen Er‐Qiang 
Published: September 2012

AbstractIn this article, we report the synthesis and characterization of a new end‐on side‐chain liquid crystalline polymer (SCLCP), poly[4‐(4′‐alkoxyphenyloxymethylene)styrene] [denoted as Poly(n‐POMS), where n is the carbon number of the alkyl tail, n = 2, 4, 6, 8, 12, 16], with the flexible rod‐like mesogenic side‐chain directly attached to the polymer backbone without flexible spacer. The polymer was obtained by using free radical polymerization. The chemical structures of Poly(n‐POMS) and the corresponding monomer were characterized using various techniques with satisfactory analysis data. A combination analysis of differential scanning calorimetry, polarized light microscopy, small angle X‐ray scattering, and wide‐angle X‐ray diffraction has been conducted to investigate the phase behavior of Poly(n‐POMS). Poly(2‐POMS), Poly(4‐POMS), and Poly(6‐POMS) are amorphous. Poly(8‐POMS) develops partially into the liquid crystal phase, and Poly(12‐POMS) and Poly(16‐POMS) self‐assembly into the smectic A (SmA) phase. Upon increasing temperature, the phase transition of Poly(16‐POMS) follows the sequence of SmA1 ↔ SmA2 ↔ isotropic (I), which may be attributed to the conformation isomerization of the flexible rod‐like mesogens. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Intrinsic uncertainty on ab initio phase diagram and compound formation energy calculations: BCC Mo–Fe as a test case
Authors: Sodré Ney , Garcia Joelson Cott , Assali Lucy Vitoria Credidio , Gonzales‐Ormeño Pablo Guillermo , Blaha Peter , Petrilli Helena Maria , Schön Cláudio Geraldo 
Published: September 2012

AbstractAb initio electronic structure calculations, within the Kohn–Sham scheme of the density functional theory, are often considered reliable and a powerful tool to provide ground state information on intermetallic compounds. More recently, it has been used in multi‐scale intermetallic phase diagram calculations with particular importance when experimental data is lacking. In spite of this recent success, they rely on basic choices of the computational solution of the complicated quantum mechanical problem. Therefore, the calculated phase diagrams may depend on these choices. Here, we concentrate on the influence of some methodological aspects of the ab initio calculations on the resulting phase diagram, for a given statistical mechanics approach. We use the Full Potential‐Linear Augmented Plane Wave and the Projector Augmented Wave Methods to perform electronic structure calculations combined with the cluster variation method in the irregular tetrahedron approximation to calculate the BCC Mo–Fe phase diagram. It is shown that all calculated phase diagrams present similar qualitative features (an asymmetric miscibility gap), but quantitative variations are found depending on some of the basic assumptions adopted for the electronic structure calculations. Based on these results, a “natural” accuracy of the order of ± 1 kJ mol−1 can be estimated for ab initio compound formation energies.
First‐principles and empirical potential simulation study of intrinsic and carbon‐related defects in silicon
Authors: Zirkelbach F. , Stritzker B. , Nordlund K. , Schmidt W. G. , Rauls E. , Lindner J. K. N. 
Published: September 2012

AbstractResults of atomistic simulations aimed at understanding precipitation of the highly attractive wide band gap semiconductor material silicon carbide in silicon are presented. The study involves a systematic investigation of intrinsic and carbon‐related defects as well as defect combinations and defect migration by both, quantummechanical first‐principles as well as empirical potential methods. Comparing formation and activation energies, ground‐state structures of defects and defect combinations as well as energetically favorable agglomeration of defects are predicted. Moreover, accurate ab initio calculations unveil limitations of the analytical method based on a Tersoff‐like bond order potential. A work‐around is proposed in order to subsequently apply the highly efficient technique on large structures not accessible by first‐principles methods. The outcome of both types of simulation provides a basic microscopic understanding of defect formation and structural evolution particularly at non‐equilibrium conditions strongly deviated from the ground state as commonly found in SiC growth processes. A possible precipitation mechanism, which conforms well to experimental findings and clarifies contradictory views present in the literature is outlined (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Silicon nanostructures in silicon oxynitride for PV application: effect of argon
Authors: Ehrhardt Fabien , Ferblantier Gérald , Ulhaq‐Bouillet Corinne , Muller Dominique , Slaoui Abdelilah 
Published: September 2012

AbstractSilicon rich silicon oxynitride (SRSON) were deposited by ECR‐PECVD to form silicon nanostructures. The effect of argon flow during the deposition was investigated. The silicon nanoparticles were fabricated by a classical thermal treatment of SRSON films. The structural properties of the SRSON films were investigated by RBS and FTIR measurements. We show that the silicon excess in the SiOxNy matrix changes slightly with Ar flow but it has a significant impact on the silicon nanoparticles morphology embedded in the silicon oxynitride layer. Different shapes for silicon nanostructures ranging from separated Si nanocrystals to Si nanocolumns were formed as studied by energy‐filtred transmission electron microscopy analysis (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Porosity dependence of positive magnetoconductance in n‐type porous silicon
Authors: Chouaibi Bassem , Radaoui Moufid , Benfredj Amel , Romdhane Samir , Bouaïcha Mongi , Bouchriha Habib 
Published: September 2012

AbstractPositive magnetoconductance (MC) on n‐type porous silicon (PS) based devices was observed at room temperature for low static magnetic field (under 6000 G). We found that the measured MC decreases when the film porosity is increased. Obtained results were analyzed by means of the quasi‐1D weak localization (WL) theory. From the dependence of the MC vs. applied magnetic field, we determine the phase coherence length Lϕ. Good agreement between theoretical and experimental results was found (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of photo‐ and electroluminescence of hydrogenated microcrystalline silicon solar cells
Authors: Müller Thomas C. M. , Pieters Bart E. , Kirchartz Thomas , Carius Reinhard , Rau Uwe 
Published: September 2012

AbstractPhotoluminescence (PL) and electroluminescence (EL) have received much attention as characterization techniques for photovoltaic devices. The methods are applied to study e.g. optical band‐gap, defect states, or quasi‐Fermi level splitting. Spatially resolved EL imaging is used to derive local junction voltage differences making it a fast inline characterization method for solar modules. However, the interpretation of EL and PL experiments on hydrogenated microcrystalline silicon (µc‐Si:H) solar cells is more complex hampering the direct determination of local voltage differences. In this work we integrated an existing model for PL of µc‐Si:H silicon with a commercial device simulator for thin‐film silicon devices. This way we extended the existing model from a spatially zero dimensional model to a one dimensional model which can also model EL. Furthermore the connection with an electrical device simulator enables the consistent modeling of EL, PL, and the electrical properties of the device. We compared experimental and simulation results for EL, PL and dark‐, and illuminated‐ current/voltage characteristics over a wide temperature range (80 – 300 K). The simulations and experiments are in good agreement in the temperature range from 170 K up to room temperature. In experiments we observed several effects which cannot be explained in the previous zero dimensional model (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A simplified Extended Kalman Filter for the global operational soil moisture analysis at ECMWF
Authors: de Rosnay Patricia , Drusch Matthias , Vasiljevic Drasko , Balsamo Gianpaolo , Albergel Clément , Isaksen Lars 
Published: September 2012

AbstractA new land surface analysis system based on a simplified point‐wise Extended Kalman Filter (EKF) was implemented at the European Centre for Medium‐Range Weather Forecasts in the global operational Integrated Forecasting System (IFS) in November 2010. This system will allow consistent and optimal analyses of land surface parameters like soil moisture, surface temperatures, snow and vegetation properties. As part of the system implementation, the surface analysis structure has been revised to permit an independent and parallel computation with the upper‐air 4D‐Var analysis. The new analysis system is used for the soil moisture analysis, replacing the previous Optimal Interpolation (OI) scheme. Similar to the OI system, the simplified EKF uses 2 m air temperature and relative humidity observations from the SYNOP (land surface synoptic report) ground‐based networks to analyse soil moisture. This paper describes the new land surface analysis, its application for analysing soil moisture, and initial verification results which supported its operational implementation at ECMWF. The performance is evaluated based on a set of one‐year analysis experiments. The simplified EKF is compared to the OI, on soil moisture, 2 m temperature and relative humidity, showing a consistent improvement on screen‐level parameters and soil moisture forecasts. To demonstrate the potential of the new analysis scheme, soil moisture derived from ASCAT (Advanced Scatterometer) has been assimilated through the simplified EKF.
Anatomical evaluation and stress distribution of intact canine femur
Authors: Verim Ozgur , Tasgetiren Suleyman , Er Mehmet S. , Ozdemir Vural , Yuran Ahmet F. 
Published: September 2012

AbstractBackgroundIn the biomedical field, three‐dimensional (3D) modeling and analysis of bones and tissues has steadily gained in importance. The aim of this study was to produce more accurate 3D models of the canine femur derived from computed tomography (CT) data by using several modeling software programs and two different methods.MethodThe accuracy of the analysis depends on the modeling process and the right boundary conditions. Solidworks, Rapidform, Inventor, and 3DsMax software programs were used to create 3D models. Data derived from CT were converted into 3D models using two different methods: in the first, 3D models were generated using boundary lines, while in the second, 3D models were generated using point clouds.ResultsStress analyses in the models were made by ANSYS v12, also considering any muscle forces acting on the canine femur. When stress values and statistical values were taken into consideration, more accurate models were obtained with the point cloud method.ConclusionIt was found that the maximum von Mises stress on the canine femur shaft was 34.8 MPa. Stress and accuracy values were obtained from the model formed using the Rapidform software. The values obtained were similar to those in other studies in the literature. Copyright © 2012 John Wiley & Sons, Ltd.
Investigation of energy gene expressions and community structures of free and attached acidophilic bacteria in chalcopyrite bioleaching
Authors: Zhu Jianyu , Jiao Weifeng , Li Qian , Liu Xueduan , Qin Wenqing , Qiu Guanzhou , Hu Yuehua , Chai Liyuan 
Published: September 2012

Abstract
In order to better understand the bioleaching mechanism, expression of genes involved in energy conservation and community structure of free and attached acidophilic bacteria in chalcopyrite bioleaching were investigated. Using quantitative real-time PCR, we studied the expression of genes involved in energy conservation in free and attached Acidithiobacillus ferrooxidans during bioleaching of chalcopyrite. Sulfur oxidation genes of attached A. ferrooxidans were up-regulated while ferrous iron oxidation genes were down-regulated compared with free A. ferrooxidans in the solution. The up-regulation may be induced by elemental sulfur on the mineral surface. This conclusion was supported by the results of HPLC analysis. Sulfur-oxidizing Acidithiobacillus thiooxidans and ferrous-oxidizing Leptospirillum ferrooxidans were the members of the mixed culture in chalcopyrite bioleaching. Study of the community structure of free and attached bacteria showed that A. thiooxidans dominated the attached bacteria while L. ferrooxidans dominated the free bacteria. With respect to available energy sources during bioleaching of chalcopyrite, sulfur-oxidizers tend to be on the mineral surfaces whereas ferrous iron-oxidizers tend to be suspended in the aqueous phase. Taken together, these results indicate that the main role of attached acidophilic bacteria was to oxidize elemental sulfur and dissolution of chalcopyrite involved chiefly an indirect bioleaching mechanism.
Generating a pronunciation dictionary for European Portuguese using a joint-sequence model with embedded stress assignment
Authors: Veiga Arlindo , Candeias Sara , Perdigão Fernando 
Published: September 2012

AbstractThis paper addresses the problem of grapheme to phoneme conversion to create a pronunciation dictionary from a vocabulary of the most frequent words in European Portuguese. A system based on a mixed approach funded on a stochastic model with embedded rules for stressed vowel assignment is described. The implemented model can generate pronunciations from unrestricted words; however, a dictionary with the 40k most frequent words was constructed and corrected interactively. The dictionary includes homographs with multiplepronunciations. The vocabulary was defined using the CETEMPúblico corpus. The model and dictionary are publicly available.
Semantifying queries over large-scale Web search engines
Authors: Papadakis Ioannis , Stefanidakis Michalis , Stamou Sofia , Andreou Ioannis 
Published: September 2012

Abstract
In many situations, searching the web is synonymous to information seeking. Currently, web search engines are the most popular vehicle via which people get access to the web. Their popularity is partially due to the intrinsic way that people interact with them, i.e., by typing some keywords to the corresponding input box. Despite their popularity, search engines often fail to satisfy certain information needs, especially when the latter are haze and poorly articulated. In this paper, we focus on the occasions when large-scale web search engines find it difficult to cope with specific information-seeking behaviors and we accordingly introduce a query construction service that is targeted towards the solution of this problem. The proposed service leverages information coming from various DBpedia datasets and provides an intuitive GUI via which searchers determine the semantic orientation of their queries before these are addressed to the underlying search engine. The evaluation of the query construction service justifies the motive of this paper and indicates that it can considerably improve the searchers’ querying ability when search engines fail to provide adequate help.
N1‐(quinolin‐2‐ylmethyl)butane‐1,4‐diamine, a polyamine analogue, attenuated injury in in vitro and in vivo models of cerebral ischemia
Authors: Cen Juan , Liu Lu , He Ling , Liu Man , Wang Chao‐Jie , Ji Bian‐Sheng 
Published: September 2012

AbstractIt has been widely recognized that glutamate (Glu)‐induced cytotoxicity, intracellular calcium overload and excessive free radical production are the key players in the development and progression of ischemic brain injury. Since MK‐801, an antagonist of N‐methyl‐d‐aspartate (NMDA) receptor, showed many adverse reactions that hampered its clinical applications, development of safe and effective agent for the treatment of cerebral ischemia is eagerly required. This study was to investigate the effects of N1‐(quinolin‐2‐ylmethyl)butane‐1,4‐diamine (QMA), a polyamine analogue, on the in vitro and in vivo models of cerebral ischemic damage. The results revealed that pretreatment with QMA could attenuate Glu, putrescine (Put) and oxygen‐glucose deprivation (OGD)‐induced cell death, lipid peroxidation as well as the elevation of reactive oxygen species (ROS) and intracellular [Ca2+]i in pheochromocytoma (PC12) cells and in rat primary cortical neurons. The results also demonstrated that QMA could inhibit NMDA‐mediated intracellular [Ca2+]i accumulation in rat primary cortical neurons and reduce brain infarct volume in middle cerebral artery occlusion (MCAO) rats. The present report suggested that polyamines played a crucial role in the pathological processes of cerebral ischemic damage and that QMA or other novel polyamine analogues could be promising therapeutic candidates for stroke by virtue of their anti‐hypoxia and antioxidation property.
Stabilizing effect of flexibility in the wake of a flapping foil
Authors: Marais C. , Thiria B. , Wesfreid J. E. , Godoy-Diana R. 
Published: September 2012

AbstractThe wake of a flexible foil undergoing pitching oscillations in a low-speed hydrodynamic tunnel is used to examine the effect of chordwise foil flexibility in the dynamical features of flapping-based propulsion. We compare the regime transitions in the wake with respect to the case of a rigid foil and show that foil flexibility inhibits the symmetry breaking of the reverse Bénard–von Kármán wake reported in the literature. A momentum balance calculation shows the average thrust to be up to three times greater for the flexible foil than for the rigid foil. We explain both of these observations by analysing the vortex dynamics in the very near wake.