54 research outputs found
Detection of soluble interleukin-2 receptor and soluble intercellular adhesion molecule-1 in the effusion of otitis media with effusion
We measured sIL-2R, TNF-α and sICAM-1 in the sera and middle ear effusions (MEEs) of patients with otitis media with effusion (OME). Although there was no signmcant difference between the sIL-2R levels of the serous and mucoid MEEs, they were significantly higher than serum sIL-2R levels of OME patients and healthy controls. TNF-α levels of the mucoid MEEs were significantly higher than those of the serous type. However, TNF-α was rarely detected in the sera of OME patients or healthy controls. We observed significant differences between the serous and mucoid MEEs with respect to their sICAM-1 levels, which were also higher than serum slCAM-1 levels of OME patients and healthy controls. Our findings suggested that IL-2, TNF-α and ICAM-1 could be significantly involved in the pathogenesis of OME through the cytokine network
Catalytic Enantioselective Cross-Couplings of Secondary Alkyl Electrophiles with Secondary Alkylmetal Nucleophiles: Negishi Reactions of Racemic Benzylic Bromides with Achiral Alkylzinc Reagents
We have developed a nickel-catalyzed method for the asymmetric cross-coupling of secondary electrophiles with secondary nucleophiles, specifically, stereoconvergent Negishi reactions of racemic benzylic bromides with achiral cycloalkylzinc reagents. In contrast to most previous studies of enantioselective Negishi cross-couplings, tridentate pybox ligands are ineffective in this process; however, a new, readily available bidentate isoquinoline–oxazoline ligand furnishes excellent ee’s and good yields. The use of acyclic alkylzinc reagents as coupling partners led to the discovery of a highly unusual isomerization that generates a significant quantity of a branched cross-coupling product from an unbranched nucleophile
Mechanism and Enantioselectivity in Palladium-Catalyzed Conjugate Addition of Arylboronic Acids to β‑Substituted Cyclic Enones: Insights from Computation and Experiment
Enantioselective conjugate additions of arylboronic acids to β-substituted cyclic enones have been previously reported from our laboratories. Air- and moisture-tolerant conditions were achieved with a catalyst derived in situ from palladium(II) trifluoroacetate and the chiral ligand (S)-t-BuPyOx. We now report a combined experimental and computational investigation on the mechanism, the nature of the active catalyst, the origins of the enantioselectivity, and the stereoelectronic effects of the ligand and the substrates of this transformation. Enantioselectivity is controlled primarily by steric repulsions between the t-Bu group of the chiral ligand and the α-methylene hydrogens of the enone substrate in the enantiodetermining carbopalladation step. Computations indicate that the reaction occurs via formation of a cationic arylpalladium(II) species, and subsequent carbopalladation of the enone olefin forms the key carbon–carbon bond. Studies of nonlinear effects and stoichiometric and catalytic reactions of isolated (PyOx)Pd(Ph)I complexes show that a monomeric arylpalladium–ligand complex is the active species in the selectivity-determining step. The addition of water and ammonium hexafluorophosphate synergistically increases the rate of the reaction, corroborating the hypothesis that a cationic palladium species is involved in the reaction pathway. These additives also allow the reaction to be performed at 40 °C and facilitate an expanded substrate scope
Electric field effect on magnetic anisotropy for Fe-Pt-Pd alloys
The electric field effect on magnetic anisotropy was investigated for the
FePt1-xPdx alloy films with
perpendicular magnetic anisotropy. The polar magneto-optical Kerr (p-MOKE) loops were
measured under the electric field application in order to evaluate the electric
field-induced perpendicular magnetic anisotropy change per area
(Δεperpt). A clear change in the saturation
field of p-MOKE loop was observed for FePt by varying the applied electric field
(ΔE). In the case of FePt,
Δεperpt divided by ΔE was
evaluated to be -129 (fJ/Vm). We found that the magnitude of
Δεperpt / ΔE was
significantly reduced with increasing x
Mechanism and Enantioselectivity in Palladium-Catalyzed Conjugate Addition of Arylboronic Acids to β‑Substituted Cyclic Enones: Insights from Computation and Experiment
Enantioselective
conjugate additions of arylboronic acids to β-substituted
cyclic enones have been previously reported from our laboratories.
Air- and moisture-tolerant conditions were achieved with a catalyst
derived <i>in situ</i> from palladiumÂ(II) trifluoroacetate
and the chiral ligand (<i>S</i>)-<i>t</i>-BuPyOx.
We now report a combined experimental and computational investigation
on the mechanism, the nature of the active catalyst, the origins of
the enantioselectivity, and the stereoelectronic effects of the ligand
and the substrates of this transformation. Enantioselectivity is controlled
primarily by steric repulsions between the <i>t</i>-Bu group
of the chiral ligand and the α-methylene hydrogens of the enone
substrate in the enantiodetermining carbopalladation step. Computations
indicate that the reaction occurs via formation of a cationic arylpalladiumÂ(II)
species, and subsequent carbopalladation of the enone olefin forms
the key carbon–carbon bond. Studies of nonlinear effects and
stoichiometric and catalytic reactions of isolated (PyOx)ÂPdÂ(Ph)I complexes
show that a monomeric arylpalladium–ligand complex is the active
species in the selectivity-determining step. The addition of water
and ammonium hexafluorophosphate synergistically increases the rate
of the reaction, corroborating the hypothesis that a cationic palladium
species is involved in the reaction pathway. These additives also
allow the reaction to be performed at 40 °C and facilitate an
expanded substrate scope
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