Search

In recent years it has spread the use of suspensions containing nanometre sized particles, known as nanofluids, in many applications owing the good properties having nanocrystalline materials. One of the main advantages of using nanofluids is its high stability, which causes the particles do not settle over long periods of time. This stability depends on the preparation conditions such as pH, the presence of electrolytes or the solids content. Moreover, there are a number of physical properties which are influenced and altered by agglomeration of the particles. This article will analyze all the variables that affect agglomeration of the particles, nanofluids stability and properties from which it can obtain information on the state of suspension. It then lays out the different methods of dispersion of nanoparticles and their effectiveness.En los últimos años se ha extendido el uso de suspensiones conteniendo partículas de tamaño nanométrico, conocidas como nanofluidos, en múltiples aplicaciones debido las buenas propiedades que presentan los materiales nanoparticulados. Una de las principales ventajas que presenta el uso de nanofluidos es su elevada estabilidad, que hace que las partículas no sedimenten durante largos periodos de tiempo. Esta estabilidad depende de las condiciones de preparación tales como el pH del medio, la presencia de electrolitos en el medio o el contenido en sólidos. Por otra parte, existen una serie de propiedades físicas que se ven influenciadas y alteradas por el estado de aglomeración de las partículas. En este artículo se analizarán todas las variables que influyen en el estado de aglomeración de las partículas y la estabilidad de los nanofluidos, así como las propiedades a partir de las cuales se puede obtener información sobre el estado de la suspensión. Además, se exponen los diferentes métodos de dispersión de nanopartículas y su efectividad.

Microstructural changes that occur during heat treatment of copper-nickel-zinc ferrites have been studied. The process of precipitation of the two types of crystals that occur during the sintering process has been analyzed. It is found that this process depends on dry relative density of the press specimens and on the following sintering parameters: sintering temperature, sintering time and cooling rate of the thermal cycle. Crystal precipitates characterization have been done by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These techniques have allowed to determine the nature of these crystals, which in this case correspond to zinc and copper oxides. It has been used two chemical reactions to explain the bulk precipitation and subsequent re-dissolution of these crystal precipitates during sintering.En este trabajo se han estudiado los cambios microestructurales que se producen durante el tratamiento térmico de las ferritas de cobre-níquel-cinc y se ha analizado el proceso de precipitación de los dos tipos de cristales que aparecen durante el proceso de sinterización. Se ha encontrado que este proceso depende de la densidad relativa en seco de las muestras compactadas y de las siguientes variables de la etapa de sinterización: temperatura y tiempo de sinterización y velocidad de enfriamiento. La caracterización de los cristales precipitados se ha realizado por microscopía electrónica de barrido (MEB), microanálisis por dispersión de energía de rayos X (EDX), difracción de rayos X (DRX), y espectroscopía de fotoelectrones de rayos X (XPS). Estas técnicas han permitido determinar la naturaleza de estos cristales, que en este caso corresponden a los óxidos de cinc y de cobre. Se han propuesto dos reacciones químicas que permiten explicar el proceso de precipitación y la posterior re-disolución de estos cristales precipitados durante la sinterización de las muestras.

Spray drying is a unit operation very common in many industrial processes. For each particular application, the resulting granulated material must possess determined properties that depend on the conditions in which the spray drying processing has been carried out, and whose dependence must be known in order to optimize the quality of the material obtained. The large number of variables that influence on the processes of matter and energy transfer and on the formation of granular material has required a detailed analysis of the drying process. Over the years there have been many studies on the spray drying processing of all kind of materials and the influence of process variables on the drying kinetics of the granulated material properties obtained. This article lists the most important works published for both the spray drying processing and the drying of individual droplets, as well as studies aimed at modeling the drying kinetics of drops.El proceso de secado por atomización es una operación unitaria que interviene en numerosas aplicaciones industriales. Para cada aplicación en concreto, el material granulado resultante debe poseer unas propiedades determinadas que dependen de las condiciones en las que se lleve a cabo el secado por atomización, y cuya dependencia debe conocerse para así optimizar la calidad del material obtenido. El gran número de variables que influyen en los procesos de transferencia de materia y energía que tienen lugar, y en la formación del material granulado, han hecho necesario el análisis en detalle del proceso de secado. A lo largo de los años han sido muchos los estudios realizados sobre el secado por atomización y la influencia de las variables del proceso en la cinética de secado y las propiedades del material granulado obtenido, para todo tipo de materiales. En este artículo se recogen los trabajos más importantes publicados correspondientes tanto al secado por atomización como al secado de gotas individuales, así como los estudios cuyo objetivo es el modelado de la cinética de secado de gotas.

The main objective of this work was to isolate and characterize viruses that infect both Saccharomyces and other Flor veil-forming genera and suggest the possible consequences they can have on the processes of formation of the Flor veil of typical D.O. Jerez-Xèrés-Sherry wines. Results obtained show that different Flor veil yeast strains isolated in Fino wines and in Amontillados presented a great resistance to ethanol and all of them presented infection by Totiviruses. These were identified after the extraction of double-stranded RNA and amplified by multiplex PCR with specific primers for the most common viruses involved in the killer factor. Subsequently, the same strains of both the S. cerevisiae species and Wickerhamomyces anomalus were subjected to an antiviral treatment with ribavirin. After microbiological analysis with Methylene Blue (MB) plates and by rt-PCR, it was determined that most of them did not show killer factor and the viruses involved in it had been correctly eliminated under the treatment with ribavirin. Subsequently, competition and implantation experiments of the treated and untreated yeasts were carried out against their controls. The wines inoculated with yeasts infected by Totiviruses showed to be dominant in all cases.

Abstract The wines produced in the Jerez-Xérès-Sherry Designation of Origin fall within the category of Fortified Wines, according to Regulation 1308/2013 of the European Parliament, which stipulates that they must be exclusively fortified with wine alcohol, with an acquired alcoholic strength between 95.0% and 96.0%. However, there are other alternative alcohols whose behavior is unknown but could be equally effective in the development of biological aging, with an impact on the final product quality and lower economic costs. This study examines the effect of using malt alcohols, grape pomace, agave, sugarcane, and cereal alcohols, as well as wine alcohols obtained through different distillation methods and at varying alcohol concentrations, for fortifying wines subjected to biological aging. The development of the "flor" yeast veil will be evaluated under each aging condition and isolated and characterized using molecular techniques. Additionally, the base wine fortified with the different alcohols will be monitored and analyzed both physicochemically and organoleptically.

The EC 2019/187 shows the rules for the usage of ethyl alcohols to fortify wines. These must be obtained from products derived from agriculture and the use of alcohols of mineral or chemical origin is not authorized. The ethyl alcohols authorized for the fortification in the D.O. Sherry have wine origin. But, there are other alcohols that could be equally productive and at a lower economic cost, such as beet or sugar cane alcohol. The effect that different types of ethyl alcohols may have on the yeasts of flor remains unknown. Our goal was to analyze the effects of other alcohols (beet, sugar cane, etc.) on the development of the veil of flor. In this way, the yeasts that constitute the veil of flor of Fino wines were isolated and identified by microbiological techniques and characterized by molecular tools and by biochemical and microbiological tests such as cellular hydrophobicity, flocculation, acetic acid production, etc. Then, base wines were fortified with different distilled alcohols, such as malt brandy, tequila, among others. Biological aging under the veil of flor was monitored to later determine the volatile fractions. Alcohol from sugar cane could be a promising alternative to fortify Fino wines.

The effects of fluorine and nitrogen substitution for oxygen in aluminosilicate glasses, effectively oxyfluoronitride ( OFN) glasses, modified by calcium, calcium-yttrium or calcium-magnesium on thermal and physical/mechanical properties have been compared. Thus, 42 glasses in the Ca-(Mg)-(Y)-Si-Al-O-(N)-(F) system have been prepared and characterized with respect to density ( ρ), molar volume ( MV), compactness (C), free volume ( FV), glass transition temperatures measured by DTA (Tg, DTA) and dilatometry (Tg,dil), dilatometric softening point ( TDS), microhardness (μHv) and Young's modulus (E). Gradients of property variation with nitrogen or fluorine substitutions for oxygen are similar for all three different oxyfluoronitride glass systems and are comparable with those reported for other OFN glasses, again indicating independent and additive effects of nitrogen and fluorine. In attempting to further understand how fluorine affects the cross-link density ( CLD) in OFN glasses, it becomes apparent that it is necessary to allow for a greater contribution by aluminum in a modifier role as fluorine content is increased. This modified calculation of CLD values results in good linear fits between Tg and CLD values. This analysis clearly demonstrates and endorses the concepts that thermal properties are related to CLD while physical/mechanical properties are dependent on glass compactness. [ABSTRACT FROM AUTHOR]