Browsing by Subject "Viscosity"

Now showing 1 - 3 of 3
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    Analysis of the porosity and microhardness of glass ionomer cements
    (Kaunas University of Technology (Lithuania), 2022-02-18) Cabello Malagón, Inmaculada; Cánovas Hernández, Basilio; Martínez Hernández, Elisa; Serna Muñoz, Clara; Pérez Silva, Amparo; Ortiz Ruiz, Antonio José; Dermatología, Estomatología, Radiología y Medicina Física
    Glass ionomer cements (GICs) are currently the first-choice materials in minimally invasive dentistry and are widely used in paediatric dentistry. The objective of this study was to evaluate the influence of viscosity and mixing on porosity and the relationship between the porosity and microhardness of GICs. Nine GICs were used: EQUIA® Forte Fil, Ionostar®Plus, 3MTMKetacTM Universal AplicapTM, Riva Light Cure HV®, Riva Silver®, Riva Protect®, VitremerTM, VitrebondTM Plus and Activa BioActive RestorativeTM. Samples were prepared from each material and images were obtained by scanning electron microscopy (SEM). Using software, the number and diameter of pores, area, and percentage of area they occupied were measured. After SEM analysis, the samples were used to make surface microhardness (SMH) measurements. Ionostar® Plus, EQUIA® Forte Fil and Riva Light Cure HV® had the highest number of pores. Riva Protect® had the largest pores and the highest percentage of pore-occupied area, while Activa BioActive RestorativeTM and VitrebondTM Plus had a smaller pore size and a smaller percentage by area. Riva Silver® and EQUIA® Forte Fil showed the highest microhardness values and VitrebondTM Plus and VitremerTM the lowest. In conclusion, when the cement viscosity is low, the type of mixture determines the degree of porosity, but has less influence when viscosity is high. There was no correlation between microhardness and the porosity of GICs.
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    Open Access
    Description and comparative study of physico-chemical parameters of the teleost fish skin mucus.
    (SAGE Publications, 2015-07-01) Guardiola Abellán, Francisco Antonio; Cuartero, María; Collado-González, Mar; Arizcún, Marta; Díaz Baños, F. Guillermo; Meseguer, José; Esteban Abad, María de los Ángeles; Biología Celular e Histología
    The study of mucosal surfaces, and in particular the fish skin and its secreted mucus, has been of great interest recently among immunologists. Measurement of the viscosity and other physico-chemical parameters (protein concentration, pH, conductivity, redox potential, osmolality and density) of the skin mucus can help to understand its biological functions. We have used five marine species of teleost: gilthead seabream (Sparus aurata L.), European sea bass (Dicentrarchus labrax L.), shi drum (Umbrina cirrosa L.), common dentex (Dentex dentex L.) and dusky grouper (Epinephelus marginatus L.), all of them with commercial interest in the aquaculture of the Mediterranean area. Mucus showed a direct shear- and temperature-dependent viscosity, with a non-Newtonian behavior, which differed however between two groups: one with higher viscosity (D. labrax, U. cirrosa, D. dentex) and the other with lower viscosity (S. aurata, E. marginatus). In addition, there was a clear interrelation between density and osmolality, as well as between density and temperature. Taking into account that high values of viscosity should improve the barrier effect against pathogens but low values of viscosity are needed for good locomotion characteristics, our results may help elucidate the relationship between physico-chemical and biological parameters of skin mucus, and disease susceptibility.
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    Non-Newtonian viscosity of dilute polymer solutions
    (2005-01-20) Pamies, Ramón; López Martínez, M. Carmen; Hernández Cifre, José Ginés; García de la Torre, José; Química Física