700 research outputs found
A designed and potentially decadentate ligand for use in lanthanide(III) catalysed biomass transformations: targeting diastereoselective trans-4,5-diaminocyclopentenone derivatives
The goal of this study was to design a ligand system which can accommodate single lanthanide(III)-ions and investigate the properties of the resulting complexes. The complexes of all the accesible lanthanides and yttrium with the new ligand LH6 = N,N′-dimethyl-N,N′-ethylene-bis(5-bromo-3-(1H-benzimidazol-2-yl)hydrazineylidene)-2-hydroxybenzylamine) were obtained in high yield at room temperature under aerobic reaction conditions. The corresponding compounds were characterised using X-ray diffraction, FT-IR, elemental analysis and the optical properties of all complexes were investigated using UV-vis and fluorescence spectroscopy. The air stable complexes efficiently transform biomass furfural to trans-4,5-cyclopentenones in high yield
Electrokinetic behavior of two touching inhomogeneous biological cells and colloidal particles: Effects of multipolar interactions
We present a theory to investigate electro-kinetic behavior, namely,
electrorotation and dielectrophoresis under alternating current (AC) applied
fields for a pair of touching inhomogeneous colloidal particles and biological
cells. These inhomogeneous particles are treated as graded ones with physically
motivated model dielectric and conductivity profiles. The mutual polarization
interaction between the particles yields a change in their respective dipole
moments, and hence in the AC electrokinetic spectra. The multipolar
interactions between polarized particles are accurately captured by the
multiple images method. In the point-dipole limit, our theory reproduces the
known results. We find that the multipolar interactions as well as the spatial
fluctuations inside the particles can affect the AC electrokinetic spectra
significantly.Comment: Revised version with minor changes: References added and discussion
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Sammenligning af dansk og svensk boligbyggeri:Den svensk-danske parallelbyggesag i Øresundsregionen
The effect of Coulomb interaction at ferromagnetic-paramagnetic metallic perovskite junctions
We study the effect of Coulomb interactions in transition metal oxides
junctions. In this paper we analyze charge transfer at the interface of a three
layer ferromagnetic-paramagnetic-ferromagnetic metallic oxide system. We choose
a charge model considering a few atomic planes within each layer and obtain
results for the magnetic coupling between the ferromagnetic layers. For large
number of planes in the paramagnetic spacer we find that the coupling
oscillates with the same period as in RKKY but the amplitude is sensitive to
the Coulomb energy. At small spacer thickness however, large differences may
appear as function of : the number of electrons per atom in the ferromagnetics
and paramagnetics materials, the dielectric constant at each component, and the
charge defects at the interface plane emphasizing the effects of charge
transfer.Comment: tex file and 7 figure
First-Principles Approach to Electrorotation Assay
We have presented a theoretical study of electrorotation assay based on the
spectral representation theory. We consider unshelled and shelled spheroidal
particles as an extension to spherical ones. From the theoretical analysis, we
find that the coating can change the characteristic frequency at which the
maximum rotational angular velocity occurs. The shift in the characteristic
frequency is attributed to a change in the dielectric properties of the
bead-coating complex with respect to those of the uncoated particles. By
adjusting the dielectric properties and the thickness of the coating, it is
possible to obtain good agreement between our theoretical predictions and the
assay data.Comment: 17 pages, 4 eps figures; minor revisions, accepted for publications
by J. Phys.: Condens. Matte
Electrorotation of a pair of spherical particles
We present a theoretical study of electrorotation (ER) of two spherical
particles under the action of a rotating electric field. When the two particles
approach and finally touch, the mutual polarization interaction between the
particles leads to a change in the dipole moment of the individual particle and
hence the ER spectrum, as compared to that of the well-separated particles. The
mutual polarization effects are captured by the method of multiple images. From
the theoretical analysis, we find that the mutual polarization effects can
change the characteristic frequency at which the maximum angular velocity of
electrorotation occurs. The numerical results can be understood in the spectral
representation theory.Comment: Minor revisions; accepted by Phys. Rev.
A multifunctional use of bis(methylene)bis(5-bromo-2-hydroxyl salicyloylhydrazone): From metal sensing to ambient catalysis of A3 coupling reactions
The potential use of bis(methylene)bis(5-bromo-2-hydroxylsalicyloylhydrazone) as a multifunctional fluorescence sensor for Cu(2+), Ni(2+), Co(2+) and Fe(2+) ions was investigated. The optical behaviour shows an increase in an absorption band at 408 nm which can be ascribed to the d–d transition (UV-vis) of the metal ions and a concomitant decrease in fluorescence intensity at 507 nm. The crystallographic analysis shows the binding site of the sensor to two Cu(2+) ions and confirms the stoichiometry of 1 : 2 (ligand to metal) which is in good agreement with a Job plot analysis. Furthermore the Cu(2+)-complex catalyses A3 coupling reactions at 1 mol% catalytic loading; chiral propargylamine derivatives were obtained in high yield after 24 h reaction time under ambient conditions
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