Search results for "Homogeneous"
showing 10 items of 718 documents
Water-Soluble Palladium Nanoparticles: Click Synthesis and Applications as a Recyclable Catalyst in Suzuki Cross-Couplings in Aqueous Media
2010
A new PEG-tagged material, which was prepared by a threefold copper-catalyzed [3+2] cycloaddition (click chemistry), was found to act as an efficient stabilizer for palladium nanoparticles. The newly formed material proved to be active as a recyclable catalyst in Suzuki coupling; the presence of polyether chains allowed for the catalytic runs to be conducted in aqueous media.
Pseudo-path connected homogeneous continua
2015
Abstract The main result of this paper states that every homogeneous pseudo-path connected continuum is weakly chainable, or equivalently, every homogeneous continuum connected by continuous images of the pseudo-arc is itself a continuous image of the pseudo-arc. We notice that even though there exist homogeneous path connected continua that are not continuous images of an arc (Prajs, 2002), they all are continuous images of the pseudo-arc.
Domain wall energy in quasi-one-dimensional Fe/W(110) nanostripes
2003
The magnetic susceptibility in Fe/W(110) nanostripes decreases exponentially with increasing temperature according to an Arrhenius law which indicates a quasi-one-dimensional behavior. The interface energy of the Arrhenius law corresponds to the domain wall energy of a domain wall across a single stripe, separating fluctuating regions of homogeneous magnetization. The domain wall energy increases linearly with the width of the stripes, revealing a negative offset which we attribute to boundary effects. Domain wall energies have been determined for Fe/W(110) nanostripes coated with Au and Pd and are compared to values for uncoated Fe/W(110) nanostripes in ultrahigh vacuum.
A simulation of disagreement for control of rational cheating in peer review
2013
Understanding the peer review process could help research and shed light on the mechanisms that underlie crowdsourcing. In this paper, we present an agent-based model of peer review built on three entities - the paper, the scientist and the conference. The system is implemented on a BDI platform (Jason) that allows to define a rich model of scoring, evaluating and selecting papers for conferences. Then, we propose a programme committee update mechanism based on disagreement control that is able to remove reviewers applying a strategy aimed to prevent papers better than their own to be accepted (rational cheating). We analyze a homogeneous scenario, where all conferences aim to the same leve…
Propriétés et performances de phosphines ferrocéniques dans le couplage C-O, C-S et C-N : nouvelles méthodologies de synthèse au palladium
2012
Multidentate ligands usually show great activities in low loading organometallic catalysis in palladium. Among these ligands, the use of ferrocenyl polyphosphane ligands give interesting results. Robust palladium-ferrocenyl triphosphane catalytic systems have permitted to obtain biarylamines and aryl-heteroaryl ethers in the presence of low catalytic loadings. DFT studies on catalytic cycle during formation of aryl-heteroaryl ethers were carried out. The presence of third phosphino group stabilizes a transition state which enhances the rate of the reductive elimination. Triarylamines were obtained with ferrocenyl diphosphane in the presence of 2 mol% of palladium loading. Moderate to excell…
Regularization of spherical and axisymmetric evolution codes in numerical relativity
2007
Several interesting astrophysical phenomena are symmetric with respect to the rotation axis, like the head-on collision of compact bodies, the collapse and/or accretion of fields with a large variety of geometries, or some forms of gravitational waves. Most current numerical relativity codes, however, can not take advantage of these symmetries due to the fact that singularities in the adapted coordinates, either at the origin or at the axis of symmetry, rapidly cause the simulation to crash. Because of this regularity problem it has become common practice to use full-blown Cartesian three-dimensional codes to simulate axi-symmetric systems. In this work we follow a recent idea idea of Rinne…
Testing LTB void models without the cosmic microwave background or large scale structure: new constraints from galaxy ages
2012
We present new observational constraints on inhomogenous models based on observables independent of the CMB and large-scale structure. Using Bayesian evidence we find very strong evidence for homogeneous LCDM model, thus disfavouring inhomogeneous models. Our new constraints are based on quantities independent of the growth of perturbations and rely on cosmic clocks based on atomic physics and on the local density of matter.
Detection of homogeneous precipitation regions at seasonal and annual time scales, northwest Iran
2017
Abstract Detection of homogeneous climate areas is a challenging issue, which can be affected by different criteria. One of the most prominent factors is choosing the time scale, which can lead to different spatial and temporal patterns. Total precipitation is a key factor in climatological studies, and studying its distribution is of utmost importance. The combination of principal components analysis and cluster analysis is used for homogeneous precipitation areas' detection. Hence, the spatial pattern of total precipitation was investigated in northwestern Iran during the past two decades (1991–2010) on seasonal and annual time scales. The results of clustering on each time scale were val…
Evaluation of Surface Temperature and Emissivity Derived from ASTER Data: A Case Study Using Ground-Based Measurements at a Volcanic Site
2010
Abstract The land surface temperature (LST) and emissivity (LSE) derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were evaluated in a low spectral contrast volcanic site at an altitude of 2000 m on the island of Tenerife, Spain. The test site is almost flat, thermally homogeneous, and without vegetation cover or variation in its surface composition. ASTER data correspond to six scenes, under both day- and nighttime conditions during 2008. This case study analyzes the impacts of the sources of inaccuracies using the temperature–emissivity separation (TES) algorithm. Uncertainties associated with inaccurate atmospheric correction were minimized by means…
Argon broadening of the 13CO R(0) and R(7) transitions in the fundamental band at temperatures between 80 and 297K: comparison between experiment and…
2003
We present measurements of Ar-broadening parameters for the R(0) and R(7) lines in the fundamental band of13CO at eight temperatures from 80 to 297 K. The broadening parameters are determined by simultaneous least-squares fitting of spectra recorded using a frequency stabilized diode laser spectrometer. The comparison of the broadening parameter values for R(7) derived at room temperature and different pressures from different line profiles shows that an empirical line profile, which takes into account narrowing effects (Dicke narrowing and absorber speed dependence) but neglects any correlation between collisions, is able to describe the observed lines with constant values of the narrowing…