Grand canonical ensemble of a dd-dimensional Reissner-Nordstr\"om black hole in a cavity

The grand canonical ensemble of a $d$-dimensional Reissner-Nordstr\"om black hole space in a cavity is analyzed. The realization of this ensemble is made through the Euclidean path integral approach by giving the Euclidean action for the black hole with the correct topology, and boundary conditions corresponding to a cavity, where the fixed quantities are the temperature and the electric potential. One performs a zero loop approximation to find and analyze the stationary points of the reduced action. This yields two solutions for the electrically charged black hole, $r_{+1}$, which is the smaller and unstable, and $r_{+2}$, which is the larger and stable. One also analyzes the most probable configurations, which are either a stable charged black hole or hot flat space, mimicked by a nongravitating charged shell. Making the correspondence between the action and the grand potential, one can get the black hole thermodynamic quantities, such as the entropy, the mean charge, the mean energy, and the thermodynamic pressure, as well as the Smarr formula, shown to be valid only for the unstable black hole. We find that thermodynamic stability is related to the positivity of the heat capacity at constant electric potential and area of the cavity. We also comment on the most favorable thermodynamic phases and phase transitions. We then choose $d = 5$, which is singled out naturally from the other higher dimensions as it provides an exact solution for the problem, and apply all the results previously found. The case $d = 4$ is mentioned. We compare thermodynamic radii with the photonic orbit radius and the Buchdahl-Andr\'easson-Wright bound radius in $d$-dimensional Reissner-Nordstr\"om spacetimes and find they are unconnected, showing that the connections displayed in the Schwarzschild case are not generic, rather they are very restricted holding only in the pure gravitational situation.Comment: 28 pages, 5 figure

Normal modes of Proca fields in AdS spacetime

A normal mode analysis for Proca fields in the anti-de Sitter (AdS) spacetime is given. It is found that the equations for the Proca field can be decoupled analytically. This is performed by changing the basis of the vector spherical harmonics (VSH) decomposition. The normal modes and the normal mode frequencies of the Proca equation in the AdS spacetime are then analytically determined. It is also shown that the Maxwell field can be recovered by taking the massless limit of the Proca field with care so that the nonphysical gauge modes are eliminated.Comment: 6 page

Chitosan microparticles loaded with essential oils having in view leather applications

Chitosan is a biopolymer attracting considerable attention for diverse applications due to its unique properties like biodegradability, biocompability, non-toxicity and antimicrobial activity. It is obtained by the partial N-deacetylation of chitin, which is the second most abundant polysaccharide in nature, next to cellulose. Chitosan is a viable base material for functional coatings development, namely due to its antimicrobial activity. This characteristic is especially useful for footwear applications that constitute products prone to microbial attack. In this context, developing antimicrobial coatings to be used in footwear components in direct contact with the feet are of great interest, both at industrial level (reducing possibility of material deterioration and quality loss), as well as, from the consumer’s point of view (decrease of skin infections and minor unpleasant odours). Following our previous work, where leather impregnation with chitosan was studied at laboratorial level with quite promising results, and having in view the final application (footwear leather components), where the antimicrobial effect must need to be enhanced, we have developed the idea of microencapsulate different essential oils, with recognized antimicrobial activity like lemon, oregano, eucalyptus and pine. These chitosan-based microparticles, loaded with the chosen essential oil are intended to be applied conjunctly with the chitosan coating process previously studied. Microencapsulation will ensure that the loaded core material will be progressively released, reinforcing the antimicrobial durability and effectiveness of the final product.COMPETE, QREN and EU within the project QREN-ADI-1585-ADVANCEDSHO

Chitosan-based leather functional coatings with improved antimicrobial properties

Among the interesting biological activities that have been ascribed to chitosan, the antimicrobial activity is probably the one that generates the higher number of applications. Developing antimicrobial coatings for footwear components to be used in direct contact with the feet is of great interest; both at industrial level (reducing the possibility of material deterioration and quality loss) and from the consumer’s point of view (decreasing skin infections and minimizing unpleasant odours). One weakness of this application is addressed to the durability and efficiency of the product antimicrobial activity, since it is directly associated with the availability of the positively charged R–NH3 + groups that are depleted during use

Additive manufacturing of bioactive glass in a biodegradable matrix

Bioactive glass can induce a specific and fast response in the human body that supports tissue regeneration. It is possible to control the design of customized bioapplications with advanced technologies. Although currently used in research, only a few of these technologies have been approved by the FDA to be applied in Tissue Engineering. There is dedicated additive manufacturing equipment to manufacture biomaterials. Since they are emerging technologies in emerging fields of application it is necessary to study and develop formulations with suitable processing characteristics [1]. Formulations of bioactive glass (CaO·P2O5·MgO·SiO2 system) in two different biodegradable matrices (polylactide (PLA) and polycaprolactone (PCL)) were prepared and processed by material extrusion process, namely by Fused Filament Fabrication technique.. The polymer (PLA or PCL) involves bioactive particles in biocompatible media and allows to acquire extrudable skills. The formulations with different solid contents (20–50 wt.%) were prepared using a brabender mixer type and were characterized by different techniques (e.g., X-ray diffraction (XRD), differential scanning calorimetry (DSC), melt flow index (MFI)). The inorganic particles influence the rheological and thermal properties of bioactive glass composites. The viscosity decreases with the increase of bioactive glass content in the polymer matrix. Mechanical standard samples and scaffolds were printed and characterized. Bioactive glass composites until 40 wt.% of solid content can be printed. The bioactive glass improves the mechanical resistance of composites compared to a neat polymer matrix. However, formulations with high bioactive glass solid content (50 wt.%) showed printing limitations by their brittleness and clogging tendency.publishe

EBSD Analysis of Metal Matrix Nanocomposite Microstructure Produced by Powder Metallurgy

The development of metal nanocomposites reinforced by carbon nanotubes (CNTs) remains a focus of the scientific community due to the growing need to produce lightweight advanced materials with unique mechanical properties. However, for the successful production of these nanocomposites, there is a need to consolidate knowledge about how reinforcement influences the matrix microstructure and which are the strengthening mechanisms promoting the best properties. In this context, this investigation focuses on the study of the reinforcement effect on the microstructure of an Ni-CNT nanocomposites produced by powder metallurgy. The microstructural evolution was analysed by electron backscattered diffraction (EBSD). The EBSD results revealed that the dispersion/mixing and pressing processes induce plastic deformation in the as-received powders. The dislocation structures produced in those initial steps are partially eliminated in the sintering process due to the activation of recovery and recrystallization mechanisms. However, the presence of CNTs in the matrix has a significant effect on the dislocation annihilation, thus reducing the recovery of the dislocation structures

Estudio histológico, inmuno-histoquímico y de cultivo celular de mamas humana y canina normal y cancerosa

Objetivo. Comparar las características morfológicas de células normales y cancerosas derivadas de glándulas mamarias de las especies humana y canina. Materiales y métodos. Fueron colectadas 10 muestras de parénquima mamario normal y 14 de parénquima tumoral de la especie canina, así como seis muestras de parénquima mamario normal y tres de parénquima tumoral de la especie humana. Para el cultivo de células fue utilizada la técnica de cultivo de células de mamíferos y para la histoquímica la técnica de la avidina- biotina- peroxidasa, con utilización del anticuerpo monoclonal 32-2B (anti-desmogléina-1). Resultados. A los estudios histológicos y morfológicos las células de la glándula mamaria normal humana demostraron semejanzas con las células de la glándula mamaria normal canina. Se observó adhesión y proliferación de células normales en ambas especies por aproximadamente tres meses de cultivo. Las células normales de las especies humana y canina mostraron baja actividad de proliferación cuando se compararon con las cancerosas de las especies en estudio. Los grupos de células epiteloides que se adhirieron al sustrato de los dos cultivos tuvieron dependencia de las células estromales, porque en la medida que las células fibroblastoides se retiraron, las células epiteloides detuvieron su crecimiento. Conclusiones. Comparando los resultados obtenidos por medio de análisis inmuno-histoquímico de células normales de mujeres y perras fue posible observar cambios en el patrón de coloración en células cancerosas en ambas especies, demostrando que las estructuras relacionadas con la adhesión celular (desmosomas) pueden estar alteradas

Chitosan as an antimicrobial agent for footwear leather components

In the footwear industry, microorganisms’ growth can pose problems of material deterioration with associated unpleasant smell and generate possible infections in susceptible individuals. Generally, footwear presents high relative humidity conditions that enable the growth of bacteria and fungi. Additionally, leather itself and some tannery agents such as oils and greases, provide a substrate where microorganisms can grow. In the foot, microtraumas caused by ingrown nails, abrasions and lacerations can allow microbial invasion through epidermis, resulting in skin infection. In this work, the applicability of chitosan functional coatings to leather was tested, with the purpose to develop new base materials to produce footwear components. The leather treated with chitosan was then studied for its antibacterial properties against 3 different bacteria.COMPETE, QREN and EU (project QREN-ADI-1585-ADVANCEDSHOE)

Spectrophotometric flow injection determination of total phosphorus in beer using on-line UV/thermal induced digestion

A flow injection system for the automatic determination of total phosphorus in beer is described. The developed manifold uses a two-stage photooxidation/thermal digestion procedure together with oxidizing and hydrolyzing reagents to convert all forms of phosphorus compounds to orthophosphate. Polyphosphates are hydrolyzed by acid and heat, and organo-phosphates are digested by UV-catalyzed peroxodisulfate oxidation. The orthophosphate formed is then spectrophotometrically determined by the phosphomolybdenum blue reaction, using stannous chloride as reducing agent. The results obtained for a set of 19 beer samples (with concentrations from 120 to 735 mg P/L) were in good agreement with the reference method, the maximum relative deviation found being 4.7%. Relative standard deviations for ten consecutive determinations were lower than 1.5%, and a detection limit of 1 mg P/L was achieved

Development of a prototype to access biodegradability of TPU shoe soles under controlled conditions

In the last years, the increasing problems posed by waste management have stimulated the interest in developing more sustainable and bio-based solutions for the footwear industry, including the use of biodegradable materials. As part of the NEWALK project, the objective of this work consisted in optimizing and implementing a respirometry system prototype. Besides evaluating different variables, two different approaches for measuring the evolved CO2 were assayed. Compared to manual titration, the use of conductivity offers the advantage of an automatic continuous monitoring.info:eu-repo/semantics/publishedVersio