Nonlinear-optical and micro-Raman diagnostics of thin films and nanostructures of ABO3 ferroelectrics

Ferroelectric composite two-dimensional ferroelectric/aluminum oxide nanostructures were studied. A porous aluminum oxide matrix was used as a template into which a ferroelectric precursor was introduced, followed by annealing. The prepared nanostructures were studied using optical second harmonic generation and micro-Raman scattering.     

Metallic films forming on the surface of alkali-halide crystals during thermal diffusion of intracrystalline immpurities

It was detected for the first time that films consisting of a transition-metal-based structure form (via thermal diffusion of intracrystalline impurities) on the surface of alkali-halide (LiF, NaF) crystals activated by transition metals Co, Ni, or Mn. The thickness, density, and composition of the films are shown to be different, depending on the heat treatment conditions. The crystals were annealed at temperatures varying from 473 to 1073 K in vacuum and air. The surface structures forming upon annealing in vacuum exhibit magnetic properties. The films were studied by optical, x-ray fluorescence, and electron spectroscopy to reveal the mechanisms of transition-metal film formation during thermal annealing.     

Infrared Features of Unquenched Lattice Landau Gauge QCD

The running coupling and the Kugo-Ojima parameter of unquenched lattice Landau gauge are simulated and compared with the continuum theory. Although the running coupling measured by the ghost and gluon dressing function is infrared suppressed, the running coupling has a maximum of α₀ ∼ 2 − 2.5 at around q = 0.5 GeV irrespective of the fermion actions (Wilson fermions and Kogut-Susskind (KS) fermions). The Kugo-Ojima parameter c which saturated to about 0.8 in quenched simulations becomes consistent with 1 in the MILC configurations produced with the use of the Asqtad action, after averaging the dependence on polarization directions caused by the asymmetry of the lattice. The presence of the correction factor 1 + c ₁/q ² in the running coupling depends on the lattice size and the sea quark mass. In the large lattice size and small sea quark mass, c ₁ is confirmed of the order of a few GeV. The MILC configuration of a = 0.09 fm suggests also the presence of dimension-4 condensates with a sign opposite to the dimension-2 condensates. The gluon propagator, the ghost propagator, and the running coupling are compared with recent pQCD results including an anomalous dimension of fields up to the four-loop level.     

Effect of oxygen exposure on the magnetic properties of ultrathin Co/Ge(1 1 1) films

Influences of oxygen exposure on the magnetic properties of Co/Ge(1 1 1) ultrathin films have been investigated by surface magneto-optic Kerr effect technique. As the oxygen exposure increases on Co/Ge(1 1 1) films, their magnetic properties could be modified. As an example for 15 ML Co/Ge(1 1 1) films, the coercivity increases from 730 to 920 Oe and the remanence Kerr intensity is reduced for 500 Langmuir (L) of oxygen exposure. Corresponding compositions analyzed by Auger electron spectroscopy measurement shows that the amount of oxygen on the surface layers increases with increasing the oxygen exposure time. Oxygen distributes on the topmost layers of the film. The adsorbed oxygen influences the electronic density of states of Co and results in the changes of the magnetic properties. Besides, the appearance of O/Co/Ge interface could modify the stress anisotropy, and as a result the coercivity of ultrathin Co/Ge(1 1 1) film is enhanced.     

Fatty acid binding site of mitochondrial uncoupling protein UCP2 as probed by EPR spectroscopy of spin-labeled fatty acids

Electron paramagnetic resonance (EPR) spectroscopy of spin-labeled fatty acids was used to investigate their interaction withEscherichia coli-expressed human mitochondrial uncoupling protein UCP2 refolded from inclusion bodies in nonaethylene glycol monododecyl ether (C₁₂E₉) micelles. 5-DOXYL-stearic acid and 4-PROXYL-palmitic acid bound to UCP2 exhibited additional clearly separated h_+1I, h_?1I “immobile” peaks in the low- and high-field region, respectively, separated by 42 and 44 Gauss, and extensively reduced h_+1M, h_?1M “mobile” peaks, separated by about 30 G, whereas with 7-DOXYL-stearic acid the I and M peaks were smoothed together into one wide peak. Competition of 4-PROXYL-palmitic acid with added palmitic acid, arachidonic acid, and all-cis-8,11,14-eicosatrienoic acid and of 7-DOXYL-stearic acid with arachidonic acid was indicated by the disappearance of the h_+1I, h_?1I “immobile” peaks, whereas redistribution in micelles without protein was indicated by the rising of the h_+1M, h_?1M “mobile” peaks. In conclusion, a competition of palmitic, arachidonic, and eicosatrienoic acid within a putative fatty acid binding site was observed for mitochondrial uncoupling protein UCP2. This finding together with the observation of EPR spectra of highly immobilized probes exclusively in the presence of the recombinant UCP2 suggest the existence of a fatty acid binding site on UCP2 which is a prerequisite of the fatty acid cycling mechanism as previously postulated for UCP1.     

The Influence of Variable Convective Velocities on Longitudinal Diffusion

Solutions are presented for the impulsively started uniformstream and simple shear flows past a point source of momentum,which can be interpreted to describe the position and the widthof the front which transmits the knowledge of the singularitythrough a slightly viscous fluid. These understandings are thengeneralized to show that the front always moves with velocityslower than that of a (strictly monotonic) convective velocity,and also that its width always grows faster than with simplediffusion. Finally, a remarkably simple, exact expression is given forvorticity due to a simple shear flow past a point vortex.     

Efficient multi and single line atomic fluorine lasers

Intense multi- and single-line laser operation is reported from semiconductively preionised atomic fluorine lasers employing an optimised capacitor transfer excitation circuitry. The performance and spectral characteristics of these lasers are discussed and compared to the characteristics of previously described atomic fluorine lasers. The efficiency of one of these lasers described, at optimum conditions, is reaching a value as high as 0.14%. To the best of our knowledge, this is the highest efficiency reported up date, for an atomic fluorine laser.