bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of peripheral ligand bulk on nitrogen activation by three‐coordinate molybdenum complexes—A theoretical study using the ONIOM method
Authors: Brookes Nigel J. , Graham David C. , Christian Gemma , Stranger Robert , Yates Brian F. 
Published: March 2009

AbstractElectronic structure methods have been combined with the ONIOM approach to carry out a comprehensive study of the effect of ligand bulk on the activation of dinitrogen with three‐coordinate molybdenum complexes. Calculations were performed with both density functional and CCSD(T) methods. Our results show that not only is there expected destabilization of the intermediate on the pathway due to direct steric interactions of the bulky groups, but also there is significant electronic destabilization as the size of the ligand increases. This latter destabilization is due to the inability of the molecule to accommodate a rotated amide group bound to the molybdenum once the amide reaches a certain size. This destabilization also leads to a clear preference for the triplet intermediate (rather than the singlet intermediate) for bulky substituents which is in agreement with experiment. Overall, the calculated reaction profile for the bulky substituents shows a good correlation with the available experimental data. © 2009 Wiley Periodicals, Inc. J Comput Chem 2009
Reducing the bias and uncertainty of free energy estimates by using regression to fit thermodynamic integration data
Authors: Shyu Conrad , Ytreberg F. Marty 
Published: March 2009

AbstractThis report presents the application of polynomial regression for estimating free energy differences using thermodynamic integration data, i.e., slope of free energy with respect to the switching variable λ. We employ linear regression to construct a polynomial that optimally fits the thermodynamic integration data, and thus reduces the bias and uncertainty of the resulting free energy estimate. Two test systems with analytical solutions were used to verify the accuracy and precision of the approach. Our results suggest that use of regression with high degree of polynomials provides the most accurate free energy difference estimates, but often with slightly larger uncertainty, compared to commonly used quadrature techniques. High degree polynomials possess the flexibility to closely fit the thermodynamic integration data but are often sensitive to small changes in the data points. Thus, we also used Chebyshev nodes to guide in the selection of nonequidistant λ values for use in thermodynamic integration. We conclude that polynomial regression with nonequidistant λ values delivers the most accurate and precise free energy estimates for thermodynamic integration data for the systems considered here. Software and documentation is available athttp://www.phys.uidaho.edu/ytreberg/software. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009
Paracrine action of sFLT‐1 secreted by stably‐transfected Ehrlich ascites tumor cells and therapy using sFLT‐1 inhibits ascites tumor growth in vivo
Authors: Ramachandra Sunitha , D'Souza Saritha Sandra , Gururaj Anupama E. , Shaila Melkote S. , Salimath Bharathi P. 
Published: March 2009

AbstractBackgroundVascular endothelial growth factor (VEGF) is known to play a major role in angiogenesis. A soluble form of Flt‐1, a VEGF receptor, is potentially useful as an antagonist of VEGF, and accumulating evidence suggests the applicability of sFlt‐1 in tumor suppression. In the present study, we have developed and tested strategies targeted specifically to VEGF for the treatment of ascites formation.MethodsAs an initial strategy, we produced recombinant sFLT‐1 in the baculovirus expression system and used it as a trap to sequester VEGF in the murine ascites carcinoma model. The effect of the treatment on the weight of the animal, cell number, ascites volume and proliferating endothelial cells was studied. The second strategy involved, producing Ehrlich ascites tumor (EAT) cells stably transfected with vectors carrying cDNA encoding truncated form of Flt‐1 and using these cells to inhibit ascites tumors in a nude mouse model.ResultsThe sFLT‐1 produced by the baculovirus system showed potent anti‐angiogenic activity as assessed by rat cornea and tube formation assay. sFLT‐1 treatment resulted in reduced peritoneal angiogenesis with a concomitant decrease in tumor cell number, volume of ascites, amount of free VEGF and the number of invasive tumor cells as assayed by CD31 staining. EAT cells stably transfected with truncated form of Flt‐1 also effectively reduced the tumor burden in nude mice transplanted with these cells, and demonstrated a reduction in ascites formation and peritoneal angiogenesis.ConclusionsThe inhibition of peritoneal angiogenesis and tumor growth by sequestering VEGF with either sFlt‐1 gene expression by recombinant EAT cells or by direct sFLT‐1 protein therapy is shown to comprise a potential therapy. Copyright © 2009 John Wiley & Sons, Ltd.
Kinetic parameters of monoclonal antibodies ESH2, ESH4, ESH5, and ESH8 on coagulation factor VIII and their influence on factor VIII activity
Authors: Egler C. , Albert T. , Brokemper O. , Zabe‐Kühn M. , Mayer G. , Oldenburg J. , Schwaab R. 
Published: March 2009

AbstractThe murine monoclonal antibodies ESH2, ESH4, ESH5, and ESH8 specifically bind and inhibit the procoagulant activity of human coagulation factor VIII (FVIII). They are frequently used as a model of inhibitors which are raised against injected FVIII in about 25% of hemophiliacs as a serious side effect of substitution therapy. However, binding kinetics of the interaction of these antibodies with FVIII and their influence on FVIII activity (inhibition) have not yet been examined systematically. For this, we examined association and dissociation of protein:antibody interaction using surface plasmon resonance (SPR) and determined their ability to inhibit the FVIII activity in a one‐stage and a two‐stage assay. SPR‐analysis revealed that the equilibrium dissociation constants (KD) of ESH8 and ESH4 are low and in a similar range (ESH8: KD(ESH8) = 0.542 nM; ESH4: KD(ESH4) = 0.761 nM). A 5.7 times higher KD than for ESH4 was observed for ESH2 (4.33 nM), whereas ESH5 showed the highest KD of 28.8 nM. In accordance with the lowest KD, ESH8, and ESH4 reduced FVIII activity of normal human plasma almost completely in a one‐stage clot inhibition assay (ESH8: 91.9%; ESH4: 90.1%). However, ESH8 inhibited FVIII activity more efficiently as only 1.0 µg/ml ESH8 was sufficient to obtain maximum inhibition compared to up to 600 µg/ml of ESH4. Despite its attenuated KD, ESH2 inhibits FVIII:C still efficiently, reducing 61.3% of FVIII activity at a concentration of 9 µg/ml in the one‐stage clotting assay. However, a discrepancy of inhibitory efficiency was found depending on the method used to measure FVIII activity. These effects seem to be mainly caused by differences of activation time of FVIII during both FVIII activity assays. The systematic assessment of these results should support FVIII interaction studies, and can provide data to rationally test peptides/mimotopes to remove or neutralize inhibitors of FVIII activity. Copyright © 2009 John Wiley & Sons, Ltd.
Sensitive determination of amide herbicides in environmental water samples by a combination of solid‐phase extraction and dispersive liquid–liquid microextraction prior to GC–MS
Authors: Zhao Ru‐Song , Diao Chun‐Peng , Chen Qing‐Feng , Wang Xia 
Published: March 2009

AbstractIn this paper, solid‐phase extraction (SPE) in combination with dispersive liquid–liquid microextraction (DLLME) has been developed as a sample pretreatment method with high enrichment factors for the sensitive determination of amide herbicides in water samples. In SPE–DLLME, amide herbicides were adsorbed quantitatively from a large volume of aqueous samples (100 mL) onto a multiwalled carbon nanotube adsorbent (100 mg). After elution of the target compounds from the adsorbent with acetone, the DLLME technique was performed on the resulting solution. Finally, the analytes in the extraction solvent were determined by gas chromatography–mass spectrometry. Some important extraction parameters, such as flow rate of sample, breakthrough volume, sample pH, type and volume of the elution solvent, as well as salt addition, were studied and optimized in detail. Under optimum conditions, high enrichment factors ranging from 6593 to 7873 were achieved in less than 10 min. There was linearity over the range of 0.01–10 μg/L with relative standard deviations of 2.6–8.7%. The limits of detection ranged from 0.002 to 0.006 μg/L. The proposed method was used for the analysis of water samples, and satisfactory results were achieved.
Ordinary p‐Biharmonic Problems
Authors: Benedikt Jiří 
Published: March 2009

AbstractThe aim of this paper is to recall known results on boundary value problems for the quasilinear fourth order differential equation in one dimension

where p>1. The operator at the left‐hand side is often called a p‐biharmonic operator which reduces to u(4) for p = 2. It is a fourth order analogue of the well‐known p‐Laplacian. We discuss spectral properties of the corresponding eigenvalue problems, and existence and global bifurcation of solutions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time‐domain soil‐structure interaction analysis using the scaled boundary finite element method and rational stiffness approximations
Authors: Birk Carolin , Bochert Jana 
Published: March 2009

AbstractThe SBFEM is used to calculate dynamic stiffness matrices of unbounded media. Time–domain respresentations of the associated force–displacement relationship are obtained approximating the latter by rational functions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The p‐version of the FEM for computational contact mechanics
Authors: Franke David , Düster Alexander , Rank Ernst 
Published: March 2009

AbstractContact analyses are being performed in various engineering applications. Here, like in most other fields, FE codes are based on low order elements using linear or quadratic shape functions. The intention of this paper is to show that finite elements with shape functions of high polynomial degree (p‐FEM) are a very attractive alternative to low order elements, even for computational contact mechanics. One of the advantages is the possibility to enhance the element formulation with the blending function method in order to accurately discretize the given geometry, which leads in combination with high convergence rates to very efficient computations. In order to solve the problem of frictionless contact, a penalty formulation is applied in this work. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Piezoelectric Finite Shell Element for the Geometrically Nonlinear Analysis of Sensors
Authors: Schulz Katrin , Klinkel Sven , Wagner Werner 
Published: March 2009

AbstractA geometrically nonlinear finite element formulation to analyze piezoelectric shell structures is presented. The formulation is based on the mixed field variational functional of Hu–Washizu. Within this variational principle the independent fields are displacements, electric potential, strains, electric field, stresses and dielectric displacements. The mixed formulation allows an interpolation of the strains and the electric field through the shell thickness, which is an essential advantage when using a three dimensional material law. It is remarked that no simplification regarding the constitutive relation is assumed. The normal zero stress condition and the normal zero dielectric displacement condition are enforced by the independent resultant stress and resultant dielectric displacement fields. The shell structure is modeled by a reference surface with a four node element. Each node possesses six mechanical degrees of freedom, three displacements and three rotations, and one electrical degree of freedom, which is the difference of the electric potential through the shell thickness. The developed mixed hybrid shell element fulfills the in–plane, bending and shear patch tests, which have been adopted for coupled field problems. A numerical investigation of a smart antenna demonstrates the applicability of the piezoelectric shell element under the consideration of geometrical nonlinearity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An asymmetric Mixed Finite Element for incompressible Elasticity based on a modified Least‐Squares Formulation
Authors: Schwarz Alexander , Schröder Jörg 
Published: March 2009

AbstractThe main goal of this work is to derive a mixed finite element for quasi incompressible elastic problems at small strains. Basis for the element formulation is a weak form resulting from a least–squares method, see e.g. Jiang [1]. Therefore, the L2‐norm minimization of the residuals of the given first order system of differential equations leads to a functional depending on displacements, strains and stresses. In this context an enrichment of the strain space is introduced and the respective weak form is derived. The proposed approach differs from a classical least–squares method in the elimination of the additional strains on element level. As a consequence the resulting matrices become asymmetric. This reduction results in a two field formulation related to displacements and stresses. The approximation of these unknows follows the same procedures as for a conventional least–squares method, see e.g. Cai & Starke [2] or Schwarz & Schröder [6]. At the end a numerical examples for quasi incompressible elasticity is presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
3D Numerical Analysis of Concrete Degradation at Macrostructure Level
Authors: Wawrzynek Andrzej , Pilśniak Jerzy 
Published: March 2009

AbstractThis work was intended as an attempt to assess the degradation of compressed concrete sample with regard to heterogeneity. The aim of this paper is to estimate of microdamages in heterogeneous materials as such as concrete. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polyconvex Models for Arbitrary Anisotropic Materials
Authors: Ebbing V. , Schröder J. , Neff P. 
Published: March 2009

AbstractIn this work we provide polyconvex models for arbitrary anisotropic materials. The fundamental idea is the introduction of second–order, symmetric and positive definite structural tensors which are motivated by some basic crystallographic geometric relations. The deduced invariant functions automatically satisfy the polyconvexity condition and ensure the requirement of a stress free reference configuration. Restrictions coming along with the polyconvexity condition and the usage of second–order structural tensors will be pointed out. Furthermore the results of three representative fittings show the adaptability of the proposed models for the description of real anisotropic material behavior. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of initial pre‐compression of corrugated paperboard cushions on shock attenuation characteristics in repetitive impacts
Authors: Garcia‐Romeu‐Martinez M. A. , Sek M. A. , Cloquell‐Ballester V.A. 
Published: March 2009

AbstractThe use of paper as a cushioning material is motivated by its environmental advantage over polymeric materials such as expanded polystyrene. Various studies have been conducted to investigate the capability of corrugated paperboard (CPB) to act as cushioning materials for protective packaging. The studies have normally focused on performance of cushions and effects of climatic conditions on the shock attenuation in the first drop. However, no information is available to show that CPB can be engineered to produce a cushioning element with good shock attenuation in repetitive impacts. This study investigates the deterioration of the shock attenuation characteristics of CPB cushions in consecutive impacts. A series of cushion‐test style experiments on multilayer cushion pads made entirely from CPB were conducted. Each cushion was first subjected to 20 impacts, followed by simulated warehousing in a climatic chamber, and then the additional 15 impacts. The effect of initial pre‐compression strain introduced in the process of making cushion pads is discussed and demonstrated. The performance of cushions was judged not only by the maximum acceleration of shocks. Entire recorded shock pulses and calculated corresponding shock response spectra were analysed and are presented as 3D maps in order to reveal trends that occur when a cushion is subjected to multiple drops. The paper shows that the level of pre‐compression has an important effect on the degree of deterioration of cushion performance after multiple drops. As an example, the maximum acceleration for a pad pre‐compressed to 95% strain increased by less than 20% between the 1st and the 35th drop. In contrast, for 80% pre‐compression, the increase was 300%. It was found that the selection of optimum static stress should be made in conjunction with the expected number of impacts in order to optimize the cushion performance. Copyright © 2009 John Wiley & Sons, Ltd.
Confirmatory adaptive designs with Bayesian decision tools for a targeted therapy in oncology
Authors: Brannath Werner , Zuber Emmanuel , Branson Michael , Bretz Frank , Gallo Paul , Posch Martin , Racine‐Poon Amy 
Published: March 2009

AbstractThe ability to select a sensitive patient population may be crucial for the development of a targeted therapy. Identifying such a population with an acceptable level of confidence may lead to an inflation in development time and cost. We present an approach that allows to decrease these costs and to increase the reliability of the population selection. It is based on an actual adaptive phase II/III design and uses Bayesian decision tools to select the population of interest at an interim analysis. The primary endpoint is assumed to be the time to some event like e.g. progression. It is shown that the use of appropriately stratified logrank tests in the adaptive test procedure guarantees overall type I error control also when using information on patients that are censored at the adaptive interim analysis. The use of Bayesian decision tools for the population selection decision making is discussed. Simulations are presented to illustrate the operating characteristics of the study design relative to a more traditional development approach. Estimation of treatment effects is considered as well. Copyright © 2009 John Wiley & Sons, Ltd.
Reconciling the Metallicity Distributions of Gamma-ray Burst, Damped Lyman-α, and Lyman-break Galaxies atz≈ 3
Authors: Fynbo Johan P. U. , Prochaska J. Xavier , Sommer-Larsen Jesper , Dessauges-Zavadsky Miroslava , Møller Palle 
Published: March 2009

AbstractWe test the hypothesis that the host galaxies of long-duration gamma-ray bursts (GRBs) as well as quasar-selected damped Lyman-α (DLA) systems are drawn from the population of UV-selected star-forming, highzgalaxies (generally referred to as Lyman-break galaxies). Specifically, we compare the metallicity distributions of the GRB and DLA populations against simple disk models where these galaxies are drawn randomly from the distribution of star-forming galaxies according to their star-formation rate and HI cross-section respectively. We find that it is possible to match both observational distributions assuming very simple and constrained relations between luminosity, metallicity, metallicity gradients and HI sizes. The simple model can be tested by observing the luminosity distribution of GRB host galaxies and by measuring the luminosity and impact parameters of DLA selected galaxies as a function of metallicity. Our results support the expectation that GRB and DLA samples, in contrast with magnitude limited surveys, provide an almost complete census of star-forming galaxies atz≈ 3.
Stellar Populations and Dark Matter in the Milky Way Disk and in Local Group Galaxies
Authors: Grebel Eva K. 
Published: March 2009

AbstractOur knowledge on the age structure, the chemical evolution, and the kinematics of the Galactic disk has grown substantially during the last years. Recent results on the properties of the stellar populations in the Galactic disk are summarized, and ongoing and future surveys and facilities are discussed. A short overview of recent mass estimates for the Milky Way is presented, and a brief summary of some of the key properties of the Galactic companions is given. The coming decade promises major breakthroughs in understanding our Milky Way, its disk, and the role of its satellites.
Galaxy Interactions, Star Formation History, and Bulgeless Galaxies
Authors: Jogee Shardha 
Published: March 2009

AbstractHierarchical ΛCDM models provide a successful paradigm for the growth of dark matter on large scales, but they face important challenges in predicting how the baryonic components of galaxies evolve. I present constraints on two aspects of this evolution: (1) The interaction history of galaxies over the last 7 Gyr and the impact of interactions on their star formation properties, based on Jogeeet al. (2008a, b); (2) Constraints on the origin of bulges in hierarchical models and the challenge posed in accounting for galaxies with low bulge-to-total ratios, based on Weinzirl, Jogee, Khochar, Burkert, & Kormendy (2008, hereafter WJKBK08).
Mergers and Disk Survival in ΛCDM
Authors: Bullock James S. , Stewart Kyle R. , Purcell Chris W. 
Published: March 2009

AbstractDisk galaxies are common in our universe and this is a source of concern for hierarchical formation models like ΛCDM. Here we investigate this issue as motivated by raw merger statistics derived for galaxy-size dark matter halos from ΛCDM simulations. Our analysis shows that a majority (~ 70%) of galaxy halos with M0 = 1012M⊙ at z = 0 should have accreted at least one object with mass m > 1011M⊙ ≃ 3 Mdisk over the last 10 Gyr. Mergers involving larger objects m ≳ 3 × 1011M⊙ should have been very rare for Milky-Way size halos today, and this pinpoints m/M ~ 0.1 mass-ratio mergers as the most worrying ones for the survival of thin galactic disks. Motivated by these results, we use use high-resolution, dissipationless N-body simulations to study the response of stellar Milky-Way type disks to these common mergers and show that thin disks do not survive the bombardment. The remnant galaxies are roughly three times as thick and twice as kinematically hot as the observed thin disk of the Milky Way. Finally, we evaluate the suggestion that disks may be preserved if the mergers involve gas-rich progenitors. Using empirical measures to assign stellar masses and gas masses to dark matter halos as a function of redshift, we show that the vast majority of large mergers experienced by 1012M⊙ halos should be gas-rich (fgas > 0.5), suggesting that this is a potentially viable solution to the disk formation conundrum. Moreover, gas-rich mergers should become increasingly rare in more massive halos > 1012.5M⊙, and this suggest that merger gas fractions may play an important role in establishing morphological trends with galaxy luminosity.
Abundance Gradient in the Disk of NGC 300
Authors: Vlajić Marija , Bland-Hawthorn Joss , Freeman Ken C. 
Published: March 2009

AbstractThe structure of the outer parts of galactic disks and the nature of their stellar populations are fundamental to our understanding of the formation and evolution of spiral galaxies. Ages and metallicity distributions of stars in the outermost regions of spiral disks provide important clues on how and when the disks are assembled. In our earlier work we trace the extended stellar disk of NGC 300 out to a radius of at least 10 disk scale lengths, with no sign of truncation. We now revisit the outer disk of NGC 300 in order to derive the metallicity distribution of the faint stellar population in its outskirts. We find that predominantly old stellar population in the outer disk exhibits a negative abundance gradient – as predicted by the chemical evolution models – out to about 10 kpc, followed by the metallicity plateau in the outermost disk.