Aggregation and disaggregation dynamics of sedimented and charged superparamagnetic micro-particles in water suspension

This article presents results on the aggregation and disaggregation kinetics on a 1μm diameter charged superparamagnetic particles dispersed in water under a constant uniaxial magnetic field in experiments with salt (KCl) added to the suspension in order to observe the behaviour of the system when the electrical properties of the particles have been screened. These particles have an electric charge and are confined between two separated 100μm thick quartz windows, and sediment near the charged bottom wall. The electrostatic interactions that take place in this experimental setup may affect the micro-structure and colloidal stability of the suspension and thus, the dynamics of aggregation and disaggregation.     

Solid-state electrochemical analysis of Inka pottery from Qotakalli archeological site in the Cusco (Perú) area

Journal of Solid State Electrochemistry - A series of sherds from the archeological site of Qotakalli in the area of Cusco (Perú), corresponding to four different Inka periods, were studied by...     

Neighbour lists in smoothed particle hydrodynamics

Since smoothed particle hydrodynamics (SPH) is based on interactions with the closer neighbouring particles, implementing the neighbour list is a key point in terms of the high performance of the code. The efficiency of the method depends directly on how to build and use the neighbour list. In the present work, the available searching algorithms for SPH codes are analyzed. Different gridding algorithms are evaluated, the gains in efficiency obtained from reordering of particles is investigated and the cell‐linked list and Verlet list methods are studied to create the neighbour list. Furthermore, an innovative searching procedure based on a dynamic updating of the Verlet list is proposed. The efficiency of the algorithms is analyzed in terms of computational time and memory requirements. Copyright © 2010 John Wiley & Sons, Ltd.     

Photoelectro-Enzymatic Glucose Reusable Biosensor by Using Dithienylethene Mediators

In the development of colorimetric biosensors, the use of electrochromic mediators has been accepted and widely used during decades. The main drawback of these types of enzymatic substrates is the difficult recovery of the initial redox state of the molecule, which can be done electrochemically or by antioxidants addition, complicating the initially simple structure of the biosensor. those strategies are rarely followed Actually, being the disposable biosensor configuration the most extended for this detection mechanisms. Alternatively, we propose the first reported use of a diacid dithienylethene 1,2-bis(5-carboxy-2-methylthien-3-yl)cyclopentene (DTE) photoelectrochromic compound as a substrate of the horseradish peroxidase (HRP). The photoisomerization between the open (DTEo) and closed (DTEc) forms of the molecule and the respective shift in the redox potential allowed the light-induced enzymatic detection of glucose in the glucose oxidase [(GOx)]–HRP cascade system. This fast and easy control over the enzymatic substrate availability by light pulses permits a gradually consumption and the light-regeneration of the biosensor for a number of cycles. We consider the presented results transcendent in the development of reusable and light-controlled photonic biosensing systems.     

Surface acoustic waves and elastic constants of InN epilayers determined by Brillouin scattering

The surface acoustic wave velocity in InN has been experimentally determined by means of Brillouin scattering experiments on c ‐ and m ‐face epilayers. From simulations based on the Green's function formalism we determine the shear elastic constants c₆₆ and c₄₄ and propose a complete set of elastic constants for wurtzite InN. The analysis of the sagittal and azimuthal dependence of the surface acoustic wave velocity indicates a slightly different elastic behavior of the m ‐face sample that basically affects the c₄₄ elastic constant. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A balanced atmospheric model of Lorenz

Error estimates are established in terms of the Rossby number for a nonlinear Galerkin approximation to the solutions of a reduced approximation to the balanced atmosphere model of Lorenz with mass forcing. Thereby the spectral dimension of the nonlinear Galerkin approximation is linked to the Rossby number and the diffusion coefficients.     

Effect of ionic solvation on the polarographic behaviour of halide ions inN,N-dimethylformaide-water mixtures

The paloragraphic behaviour of chloride, bromide and iodide ions in severalDMF-water mixtures at a temperature of 25°C is reported. The half-wave potentials change linearly to more cathodic potentials with increasingDMF content of the solvent, up toDMF-rich compositions, where deviations are observed for chloride and iodide ions. On the other hand, theD-product varies with solvent composition, showing a sharp maximum at water-rich compositions for the three halide ions and a smooth minimum for chloride and bromide ions at highDMF content of the solvent. These results are interpreted for different solvent mixtures in terms of the solvent structure and the ionic solvation nature of halide ions.

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Effekt der Ionensolvatation auf das polarographische Verhalten von Halogenid-Ionen inN,N-Dimethylformamid-Wasser-Mischungen

Zusammenfassung Es wird über das polarographische Verhalten von Chlorid-, Bromid- und Iodid-Ionen in einigenDMF-Wasser-Mischungen bei 25°C berichtet. Die Halbwellenpotentiale ändern sich mit ansteigendemDMF-Gehalt linear in Richtung zu kathodischen Potentialen, beiDMF-reichen Zusammensetzungen werden für Chlorid und Iodid Abweichungen beobachtet. Andererseits variiert dasD-Produkt mit der Lösungsmittelzusammensetzung: bei wasserreichen Mischungen zeigt es ein scharfes Maximum für die drei Halogenid-Ionen, bei hohemDMF-Gehalt ein glattes Minimum für Chlorid und Bromid. Die Ergebnisse werden in bezug auf Lösungsmittelstruktur und Ionensolvatation der Halogenid-Ionen interpretiert.