Three dimensional system of globally modified navier-Stokes equation with delay

We prove the existence and uniqueness of strong solutions of a three-dimensional system of glob-ally modified Navier–Stokes equations with delay in the locally Lipschitz case. The asymptoticbehavior of solutions, and the existence of pullback attractor are also analyzed

Three-dimensional system of globally modified Navier-Stokes equations with delay

We prove the existence and uniqueness of strong solutions of a three-dimensional system of globally modified Navier–Stokes equations with delay in the locally Lipschitz case. The asymptotic behavior of solutions, and the existence of pullback attractor are also analyzed

Evaluating seawater quality objectives: Application to the Andalusian littoral

The University of Cadiz (southern Spain) and the Andalusian Environmental Agency (AMA) have signed an agreement to draw up a proposal of quality objectives for Andalusian littoral waters in accordance with the classification of zones approved in the Andalusian Littoral Waters Quality Objectives Regulations (Decree 14/1996, 01-16-1996, BOJA no. 19, 02-08-1996). The present paper reviews different regulations (European Union, Spain and the United States) concerning seawater quality criteria and presents the quality criteria proposed by the University of Cadiz.La Universidad de Cádiz y la Agencia de Medio Ambiente Andaluza (AMA) han desarrollado un convenio cuya finalidad es la realización de una propuesta de objetivos de calidad para las aguas litorales andaluzas según la clasificación de zonas establecida en el Decreto 14/1996, por el que se aprueba el Reglamento de Calidad de las Aguas Litorales Andaluzas (BOJA n.° 19 de 8 de febrero de 1996). En este trabajo se hace una revisión de la normativa referente a los objetivos de calidad de las aguas marinas en la Unión Europea, España y Estados Unidos. Además, se recoge la propuesta de objetivos de calidad de aguas litorales realizada por la Universidad de Cádiz.Instituto Español de Oceanografí

Tailoring the surface density of silicon nanocrystals embedded in SiOx single layers

In this article, we explore the possibility of modifying the silicon nanocrystal areal density in SiOx single layers, while keeping constant their size. For this purpose, a set of SiOx monolayers with controlled thickness between two thick SiO2 layers has been fabricated, for four different compositions (x=1, 1.25, 1.5, or 1.75). The structural properties of the SiO x single layers have been analyzed by transmission electron microscopy (TEM) in planar view geometry. Energy-filtered TEM images revealed an almost constant Si-cluster size and a slight increase in the cluster areal density as the silicon content increases in the layers, while high resolution TEM images show that the size of the Si crystalline precipitates largely decreases as the SiO x stoichiometry approaches that of SiO2. The crystalline fraction was evaluated by combining the results from both techniques, finding a crystallinity reduction from 75% to 40%, for x = 1 and 1.75, respectively. Complementary photoluminescence measurements corroborate the precipitation of Si-nanocrystals with excellent emission properties for layers with the largest amount of excess silicon. The integrated emission from the nanoaggregates perfectly scales with their crystalline state, with no detectable emission for crystalline fractions below 40%. The combination of the structural and luminescence observations suggests that small Si precipitates are submitted to a higher compressive local stress applied by the SiO2 matrix that could inhibit the phase separation and, in turn, promotes the creation of nonradiative paths

Resistencia a biocidad en cepas de Salmonella SP. aisladas de huevo

Se ha estudiado la presencia de presuntas salmonelas en la superficie de huevos comerciales, y se ha determinado la sensibilidad a biocidas para la colección de cepas ensayadas. El porcentaje de muestras positivas osciló entre el 37% y el 43%. En algunas de las marcas comerciales analizadas no se logró aislar la bacteria en los huevos analizados, mientras que en los huevos de comercios pequeños o granjas se aisló en todas las muestras ensayadas. La mayoría de las cepas fueron inhibidas a una concentración del 0.1% de los biocidas cloruro de benzalconio, cetrimida, hexadecilpiridinio, hexaclorofeno, polihexametil biguanidio o P3 oxonia. Sin embargo, en algunos casos (cetrimida, polihexametil biguanidio o P3 oxonia ) se encontró un bajo porcentaje de cepas que requerían concentraciones de biocida de hasta diez veces superiores para su inhibición. El triclosan mostró una mayor eficacia, inhibiendo al 77% de las cepas a una concentración de 0.075%. Sin embargo, el resto de las cepas fueron muy tolerantes a este biocida, siendo necesaria una concentración del 1% para su inhibición. Los resultados de este estudio sugieren la existenciaWe have studied the presence of presumptive salmonellae in comercial eggs, and the biocide tolerance of isolates. Presumptive salmonellae were detected in some 37 to 43% of samples tested. Some comercial brands were free of the bacterium, but all eggs from local stores and farms tested positive. Most isolates were inhibited by 0.1% of the biocides benzalkonium chloride, cetrimide, hexadecylpyridinium chloride, hexachlorophene, polyhexamethylen biguanide and P3 oxonia. A small percentage of isolates required up to ten-fold higher biocide concentrations for inhibition (as in the case of cetrimide, polyhexamethylen biguanide and P3 oxonia). Triclosan was apparently more effective, inhibiting 77% of isolates at 0.075%. However, the remaining of isolates only were inhibited at 1% of the biocide. Results from this study suggest that a low percentage of the Salmonella population on egg surfaces can tolerate biocides

Activation of visible up-conversion luminescence in transparent and conducting ZnO:Er:Yb films by laser annealing

Transparent and conducting ZnO:Er:Yb thin films with visible up-conversion (660-nm emission under 980-nm excitation) were fabricated by RF magnetron sputtering. The as-deposited films were found to be transparent and conducting and the activation of the Er ions in these films to produce up-conversion luminescence was achieved by different post deposition annealing treatments in air, vacuum or by laser annealing using a Nd:YVO4 laser. The structural, electrical and optical properties and the up-conversion efficiency of these films were found to be strongly influenced by the annealing method, and a detailed study is reported in this paper. It has been demonstrated that, although the air annealing was the most efficient in terms of up-conversion, laser annealing was the only method capable of activating Er ions while preserving the electrical conductivity of the doped films. It has been shown that a minimum energy was needed in laser annealing to optically activate the rare earth ions in the ZnO host material to produce up-conversion. Up-converting and transparent conducting ZnO:Er:Yb films with an electrical resistivity of 5×10-2 Ω·cm and transparency ~80% in the visible wavelength range has been achieved by laser annealing

Photoelectrical reading in ZnO/Si NCs/p-Si resistive switching devices

The increasing need for efficient memories with integrated functionalities in a single device has led the electronics community to investigate and develop different materials for resistive switching (RS) applications. Among these materials, the well-known Si nanocrystals (NCs) have demonstrated to exhibit RS properties, which add to the wealth of phenomena that have been studied on this model material platform. In this work, we present ZnO/Si NCs/p-Si resistive switching devices whose resistance state can be electrically read at 0 V under the application of low-power monochromatic illumination. The presented effect is studied in terms of the inner structural processes and electronic physics of the device. In particular, the creation of conductive filaments through the Si NC multilayers induces a low-resistance path for photogenerated carriers to get extracted from the device, whereas in the pristine state charge extraction is strongly quenched due to the insulating nature of the NC-embedding SiO2 matrix. In addition, spectral inspection of the generated photocurrent allowed unveiling the role of Si NCs in the reported effect. Overall, the hereby shown results pave the way to obtain memories whose RS state can be read under low-power conditions

Investigation on the structural changes of ZnO:Er:Yb thin film during laser annealing to fabricate a transparent conducting upconverter

A transparent and conducting ZnO:Er:Yb thin film with upconversion properties has been achieved after being annealed with continuous laser radiation just before the ablation point of the material. This work demonstrates that the laser energy preserves the conductivity of the film and at the same time creates an adequate surrounding for Er and Yb to produce visible upconversion at 660, 560, 520, and 480 nm under 980 nm laser excitation. The relation between the structural, electrical and upconversion properties is discussed. It is observed that the laser energy melts part of the material, which recrystallizes creating rare earth oxides and two different wurtzite structures, one with substitutional rare earths and oxygen vacancies (responsible for the conductivity) and the other without substitutional rare earth ions (responsible for the upconversion emission)