Phase sensitivity of light dynamics in PT-symmetric couplers

We study the sensitivity of light dynamics to the internal phase of propagating pulses in the two types of $\mathcal {PT}$ -symmetric models. The first is a waveguide array with an embedded pair of waveguides with gain and loss, called $\mathcal {PT}$ -coupler, and the second is a planar coupler which models a chain of $\mathcal {PT}$ -symmetric couplers. For the first model we investigate the soliton scattering on the mode localized on the coupler, while for second model we study the collision of two breathers. For both models we find that the light dynamics is sensitive to the internal phases of the interacting pulses. Particularly, the $\mathcal {PT}$ -symmetry breaking can take place or not, depending on the internal phases of two signals having identical other parameters.     

Coulomb attraction during the carpet growth mode of NaCl

The submonolayer growth of NaCl bilayer high-rectangular shaped islands on Ag(111) is investigated at around room temperature by using low temperature scanning tunneling microscopy. The growth at the step edges is preferred. Two kinds of islands are observed. They either grow with their non-polar edge at the step edge of Ag(111) or the islands overgrow in a carpet-like mode with the polar direction parallel to the edge. In the latter case, the Ag step is rearranged and considerable, while the NaCl layer is bent. This study clarifies the nature of the interaction of an alkali halide nanostructure with a metal step edge.     

A switch based on self-assembled thymine

The DNA base thymine is deposited at 100?K on Cu(111) and investigated and manipulated by low-temperature scanning tunneling microscopy at 5?K. At submonolayer coverage paired rows are observed. At monolayer coverage a hexagonal commensurate self-assembled layer with the methyl group pointing away from the surface forms. A reversible local manipulation of molecules within the self-assembled layer is demonstrated. This manipulation is interpreted as an out-of-plane relaxation of molecules within the layer induced by the change of the adsorption geometry of individual molecules between two meta-stable orientations. A positive field of 2-4?V leads to this local change in the molecular arrangement, while a field larger than 4?V restores the original geometry.     

Kinetics of ultrasound-assisted lipase-catalyzed glycerolysis of olive oil in solvent-free system

This work reports experimental kinetic data of solvent-free glycerolysis of olive oil using a commercial immobilized lipase (Novozym 435) under the influence of ultrasound irradiation. The experiments were performed in a mechanically stirred reactor under ultrasound irradiation, evaluating the effects of temperature (50-70 °C), enzyme concentration (2.5-10 wt%) and glycerol to oil molar ratio (0.8:1-3:1). Results show that ultrasound-assisted lipase-catalyzed glycerolysis might be a potential alternative route to conventional methods, as high contents of reaction products, especially monoglycerides, were achieved at mild irradiation power supply (∼130 W) and temperature, in a relatively short reaction time (2 h) and low enzyme content (7.5 wt%). To completeness, two simplified kinetic modeling approaches, based on the ordered-sequential bi bi mechanism and reaction stoichiometry, were employed to represent the experimental data, thus allowing a better understanding of the reaction kinetics.     

Porous membrane structures as stationary phase for capillary electrochromatography

This work presents the application of membrane technology for the fabrication of stationary phase for CEC columns using the technique based on phase inversion of polymer solution. A blend of polyimide P84 and sulphonated poly(ether ether ketone was processed via immersion precipitation dry‐wet spinning into small‐bore porous fiber. The morphology, zeta potential, and performance of the porous structure in the CEC separation were investigated. Noncharged molecules (as markers of the electroosmotic flow) and small organic compounds were injected into the column, driven under the application of voltage, and detected on the electropherogram. The proof of concept of applying porous membrane structure as stationary phase for CEC was shown and possible optimization to improve efficiency and selectivity was suggested.     

Development of a sensor for calcium based on quartz crystal microbalance

A new sensor for calcium based on a piezoelectric quartz crystal is presented. The selectivity depends on the ratio lipophilic salt/ionophore of the composition of the coating of the quartz crystal. A crystal coated with a THF solution of PVC (34.5% w/w), DOS (62.1% w/w) and 10,19-bis[(octadecylcarbamoyl) methoxyacetyl]-1,4,7,13,16-pentaoxa-10,19-diaza cycloheneicosane (3.4% w/w) and a salt/ionophore molar proportion of 60%, corresponding to a frequency decrease of the dry crystal of 6.0 kHz, showed a detection limit to calcium of 2.2 mg/L. Both a standard calcium chloride solution and a commercially balanced salt solution for tissue culture were analyzed subsequent to ion chromatographic separation. The results obtained with the sensor developed were compared with those obtained with a conductivity detector. Although the results from both detectors agreed for the standard solution, only the quartz crystal sensor was able to give reliable results for the tissue culture solution.     

Designs with block-size 6 in projective planes of characteristic 2

We construct simple 3-designs and 4-designs of block-size 6 in the classical projective planesPG(2,q),q a power of 2. All of our designs are invariant under the projective groupPGL(3,q). Aside from several infinite series of 3-designs we get some relatively small designs of independent interest, e.g. designs with parameters 4-(21, 6, 16) and 4-(73, 6, 330) defined in the planes of orders 4 and 8, respectively.     

Weighted arcs,the finite radon transform and a Ramsey problem

We establish a link between the theory of (k, v)-arcs in affine planes and a graph theoretic Ramsey problem: A (n, k)-coloring of the complete graphK _u is a coloring of the edges ofK _u withk colours such that monochromatic connected subgraphs have at mostn vertices. The Ramsey numberf(n, k) is the smallestu such thatK _u does not admit a (n, k)-coloring. Let be an affine plane of orderq. Aweighted v-arc is a function w: such that line integrals are at mostv. Themass ofw is the sum of all the weights.In certain cases the maximum massM _q (v) can be determined (maximum over all weightedv-arcs and all affine planes of orderq). This yields the exact value off(n, q + 1) for all large enoughn.