Synthetic, Crystallographic, and Computational Study of Copper(II) Complexes of Ethylenediaminetetracarboxylate Ligands

Copper(II) complexes of hexadentate ethylenediaminetetracarboxylic acid type ligands H4eda3p and H4eddadp (H4eda3p = ethylenediamine-N-acetic-N,N′,N′-tri-3-propionic acid; H4eddadp = ethylenediamine-N,N′-diacetic-N,N′-di-3-propionic acid) have been prepared. An octahedral trans(O6) geometry (two propionate ligands coordinated in axial positions) has been established crystallographically for the Ba[Cu(eda3p)]·8H2O compound, while Ba[Cu(eddadp)]·8H2O is proposed to adopt a trans(O5) geometry (two axial acetates) on the basis of density functional theory calculations and comparisons of IR and UV−vis spectral data. Experimental and computed structural data correlating similar copper(II) chelate complexes have been used to better understand the isomerism and departure from regular octahedral geometry within the series. The in-plane O−Cu−N chelate angles show the smallest deviation from the ideal octahedral value of 90°, and hence the lowest strain, for the eddadp complex with two equatorial β-propionate rings. A linear dependence between tetragonality and the number of five-membered rings has been established. A natural bonding orbital analysis of the series of complexes is also presented.

Measuring the Superfluid Fraction of an Ultracold Atomic Gas

We propose a method to measure the superfluid fraction of an atomic gas. The method involves the use of a vector potential generated by optical beams with non-zero angular momentum to simulate uniform rotation. The induced change in angular momentum of the atomic gas can be measured spectroscopically. This allows a direct determination of the superfluid fraction.Comment: 4 pages, 2 figure

Effects of Interactions on the Critical Temperature of a Trapped Bose Gas

We perform high-precision measurements of the condensation temperature of a harmonically-trapped atomic Bose gas with widely-tuneable interactions. For weak interactions we observe a negative shift of the critical temperature in excellent agreement with mean-field theory. However for sufficiently strong interactions we clearly observe an additional positive shift, characteristic of beyond-mean-field critical correlations. We also discuss non-equilibrium effects on the apparent critical temperature for both very weak and very strong interactions.Comment: 4 pages, 4 figure

Resistance to erythromycin of Campylobacter jejuni and Campylobacter coli isolated from animals and humans

The sensititivity of thermophilic Campylobacter strains isolated from caecum of broiler chickens as well as caecum and colon of pigs and human stools, were tested against erythromycin. In 16 strains isolated in broiler chickens, resistance rate was found to be 12.50%. Three of 10 strains of Campylobacter jejuni and one of 6 strains of Campylobacter coli isolated from broiler chickens were resistant to erythromycin. In 15 strains of thermophilic Campylobacters isolated from pigs, resistance rate to erythromycin was 40.00%. Resistance was exhibited more often in C. coli (50.00%) as compared to C. jejuni (20.00%). In 24 strains isolated from humans, resistance was demonstrated at the rate of 12.50%. Out of 17 strains of C. jejuni isolated from humans, resistance was exhibited in 17.65% strains. None of 7 strains of C. coli isolated from humans exhibited resistance to erythromycin. Thermophilic campylobacters, especially C. coli isolated from pigs were more resistant to erythromycin than strains isolated from humans and broiler chickens. Therefore, a great attention should be directed to the macrolides monitoring in swine farming in order to prevent resistance in animals and its subsequent spread to human

Symmetry of k·p Hamiltonian in pyramidal InAs/GaAs quantum dots: Application to the calculation of electronic structure

A method for the calculation of the electronic structure of pyramidal self-assembled InAs/GaAs quantum dots is presented. The method is based on exploiting the C-4 symmetry of the 8-band k·p Hamiltonian with the strain taken into account via the continuum mechanical model. The operators representing symmetry group elements were represented in the plane wave basis and the group projectors were used to find the symmetry adapted basis in which the corresponding Hamiltonian matrix is block diagonal with four blocks of approximately equal size. The quantum number of total quasiangular momentum is introduced and the states are classified according to its value. Selection rules for interaction with electromagnetic field in the dipole approximation are derived. The method was applied to calculate electron and hole quasibound states in a periodic array of vertically stacked pyramidal self-assembled InAs/GaAs quantum dots for different values of the distance between the dots and external axial magnetic field. As the distance between the dots in an array is varied, an interesting effect of simultaneous change of ground hole state symmetry, type, and the sign of miniband effective mass is predicted. This effect is explained in terms of the change of biaxial strain. It is also found that the magnetic field splitting of Kramer's double degenerate states is most prominent for the first and second excited state in the conduction band and that the magnetic field can both separate otherwise overlapping minibands and concatenate otherwise nonoverlapping minibands

Stacking interactions between chelate and phenyl rings in square-planar complexes of Cu, Ni, Pt and Pd

Previous analysis of geometrical parameters in the crystal structure of square-planar complexes, with and without chelate rings, of all transition metals from Cambridge Structural Database shows that there are stacking interactions between the phenyl ring and the chelate ring with delocalized -bonds. To investigate whether the type of metal atom influence this interaction we compare stacking parameters for the complexes with and without chelate rings in the complexes containing Cu(II), Ni(II), Pd(II) and Pt(II) metals. While the overall picture is similar for all four cases, complexes of Pd and Pt without chelate ring show tendency to form shorter contacts towards aromatic carbon. It was found that this behaviour is associated with the presence of cyano or isocyano derivatives as ligands.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Efficient Production of Large 39K Bose-Einstein Condensates

We describe an experimental setup and the cooling procedure for producing 39K Bose-Einstein condensates of over 4x10^5 atoms. Condensation is achieved via a combination of sympathetic cooling with 87Rb in a quadrupole-Ioffe-configuration (QUIC) magnetic trap, and direct evaporation in a large volume crossed optical dipole trap, where we exploit the broad Feshbach resonance at 402 G to tune the 39K interactions from weak and attractive to strong and repulsive. In the same apparatus we create quasi-pure 87Rb condensates of over 8x10^5 atoms.Comment: 7 pages, 5 figures; figure font compatibility improve

Transport in a Dissipative Luttinger Liquid

We study theoretically the transport through a single impurity in a one-channel Luttinger liquid coupled to a dissipative (ohmic) bath . For non-zero dissipation $\eta$ the weak link is always a relevant perturbation which suppresses transport strongly. At zero temperature the current voltage relation of the link is $I\sim \exp(-E_0/eV)$ where $E_0\sim\eta/\kappa$ and $\kappa$ denotes the compressibility. At non-zero temperature $T$ the linear conductance is proportional to $\exp(-\sqrt{{\cal C}E_0/k_BT})$. The decay of Friedel oscillation saturates for distance larger than $L_{\eta}\sim 1/\eta$ from the impurity.Comment: 4 page