Continuous-wave laser properties of 4F3/2?4I13/2 channel in the Nd3+LiNbO3:ZnO non-linear crystal

This work reports for the first time continuous-wave laser action at room temperature around 1.3 7m in Nd³⁺ doped LiNbO₃:ZnO. Optical spectroscopy has been used to determine the main laser characteristics of ⁴F_3/2‘⁴I_13/2 channel, such as emission cross section and excited-state absorption cross section at laser wavelengths. Internal optical losses have been estimated from laser gain experiments. Under non-optimal conditions laser slope efficiencies of 30% have been obtained.     

Effect of Diamine Bridge on Reactivity of Tetradentate ONNO Nickel(II) Complexes

Two new square planar ONNO nickel(II) complexes C2_core and C3_core have been synthesized and characterized by single crystal X-ray diffraction, NMR spectroscopy, thermogravimetry, and DFT calculations. The experimental results revealed the effect of the length of diamine bridge in the ligand on the behavior of the studied complexes in the reaction with N-heterocyclic aromatic amines, while DFT calculations provided a basis for the rationalization of this observation. The complex with propylenediamine bridge ( C3_core ) readily reacts with pyridine and its derivatives to form high-spin (paramagnetic) complexes with octahedral geometry as characterized by X-ray diffraction; electron-donating substituents on the pyridine ring facilitate the coordination of axial ligands. In contrast, the complex with ethylenediamine bridge ( C2_core) does not undergo such a reaction because of the high deformation energy of the core required for the formation of C2_Py complex.     

An L‐Lactate Amperometric Enzyme Electrode Based on L‐Lactate Oxidase Immobilized in a Laponite Gel on a Glassy Carbon Electrode. Application to Dairy Products and Red Wine

A biosensor based on the immobilization of Lactate oxidase in laponite–organosilasesquioxane films on glassy carbon electrode for the quantification of L ‐lactate in wine and dairy products is presented. The bioelectrode showed a very high sensitivity (0.33±0.01) A cm^?2 M^?1 and a short time response (10 s) for less than 1 U of enzyme. No significant interferences, including ascorbic acid, were detected. For red wine, matrix effects assigned to polyphenols and anthocyanins were observed, which ware easily overcome by sample dilution. Our L ‐lactate determinations were in good agreement with those of two standard methods.     

Structural changes induced on strontium barium niobate glass by femtosecond laser irradiation

Localized modification of the optical properties of erbium doped strontium barium niobate (SBN) glass has been performed using femtosecond laser irradiation. The samples, with composition SrO–BaO–Nb₂O₅–B₂O₅ and doped with 5%mol of Er³⁺, were fabricated using a melt-quenching method. The samples were irradiated with different number of pulses per spot (1–50 pulses) at two different laser fluences (2.6 and 5.6 J/cm²) by using an fs laser amplifier operating at 800 nm and generating pulses with a duration of 120 fs. Micro-luminescent microscopy, using an Ar⁺ laser as excitation source, has been used to analyze the modifications of the luminescent properties of the sample upon fs laser exposure. The emissions of the Er³⁺: ⁴I_11/2→⁴I_15/2 and ⁴I_13/2→⁴I_15/2 transitions allow appreciating the structural modifications caused by femtosecond laser exposure. The lifetimes of the levels involved in these transitions were measured inside and outside the laser irradiated region. These measurements have been compared with those obtained in bulk glass ceramic sample, which is obtained from the glass precursor by a thermal treatment in order to estimate the optimal conditions to produce nanocrystals in a localized region by ultrafast laser irradiation.     

Optimization of nano-emulsion preparation by low-energy methods in an ionic surfactant system

The low-energy emulsification method Emulsion Inversion Point (EIP) was used to prepare O/W nano-emulsions in the W/potassium oleate-oleic acid-C(12)E(10)/hexadecane ionic system. This method had not practically been used in ionic systems up to now. The resulting droplet sizes, much smaller than those obtained with the high-energy emulsification methods, depend on the composition (formulation variables) and preparation variables (addition and mixing rate). Phase diagrams, rheology measurements, and experimental designs applied to nano-emulsion droplet sizes obtained were combined to study the formation of these nano-emulsions. To obtain small droplet sizes, it is necessary to cross a direct cubic liquid crystal phase along the emulsification path, and it is also crucial to remain in this phase long enough to incorporate all of the oil into the liquid crystal. When nano-emulsion forms, the oil is already intimately mixed with all of the components, and it only has to be redistributed. Results show that the smaller droplet sizes are obtained when the liquid crystal zone is wide and extends to high water content, because in this case, during the emulsification process, the system remains long enough in the liquid crystal phase to allow the incorporation of all of the oil. Around the optimal formulation variables, the liquid crystal zone crossed during emulsification is wide enough to incorporate all of the oil whatever mixing or stirring rate is used, and then the resulting droplet size is independent of preparation variables. However, when the composition is far from this optimum, the liquid crystal zone becomes narrower and the mixing of components controls the nano-emulsion formation. High agitation rates and/or low addition rates are required to ensure the dissolution of all of the oil into this phase.     

O2 chemistry of dicopper complexes with alkyltriamine ligands. Comparing synergistic effects on O2 binding

Two dicopper(I) complexes containing tertiary N-methylated hexaaza ligands which impose different steric constraints to the Cu ions have been synthesized, and their reactivity toward O2 has been compared with a mononuclear related system, highlighting the importance of cooperative effects between the metal centers in O2 activation.     

Invertible Contractions and Asymptotically Stable ODE’S that are not \mathcal{C}^{1}-Linearizable

We present an example of a contraction diffeomorphism in infinite dimensions that is not -linearizable, and we construct a regular ordinary differential equation in a Hilbert space whose time-one map is that diffeomorphism. With this we have an example of an asymptotically stable ODE that is not -conjugate to its linear part.