Browsing by Subject "Diffusion"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Publication
    Open Access
    Assembly of Heterometallic Rigid-Rod Complexes and Coordination Oligomers from Gold(I) Metalloligands
    (American Chemical Society, 2015-06-18) Cámara, Verónica; Barquero, Natalia; Bautista, Delia; Gil-Rubio, Juan; Vicente, José; Química Inorgánica
    The reactions of TpylC6H4C≡CAuL (Tpyl = 2,2':6',2''-terpyridin-4'-yl; L = PPh3, CNXy; Xy = 2,6-dimethylphenyl) with MX2·nH2O (M = Fe, X = ClO4; M = Co, X = BF4; M = Zn, X = TfO, ClO4) in a 2:1 molar ratio give complexes [M(TpylC6H4C≡CAuL)2]X2. Similarly, the reactions of PPN[(TpylC6H4C≡C)2Au] (PPN = (Ph3P)2N) with an equimolar amount of MX2·nH2O give coordination oligomers [M{(TpylC6H4C≡C)2Au}]nXn (M = Fe, Zn, X = ClO4; M = Co, X = BF4). The complexes and oligomers have been isolated and characterized. The crystal structures of [Fe(TpylC6H4C≡CAuCNXy)2](ClO4)2 and [Co(TpylC6H4C≡CAuPPh3)2](BF4)2 have been determined by X-ray diffraction. The hydrodynamic sizes of complexes [M(TpylC6H4C≡CAuPPh3)2]X2 and coordination oligomers [M{(TpylC6H4C≡C)2 Au}]nXn have been studied by NMR diffusion spectroscopy and Dynamic Light Scattering (DLS) measurements.
  • Thumbnail Image
    Publication
    Open Access
    Human dental Pulp stem cells exhibit different biological behaviours in response to commercial bleaching products
    (MDPI, 2018-06-27) Llena, Carmen; Collado-González, Mar; Tomás Catalá, Christopher Joseph; García Bernal, David; Oñate Sánchez, Ricardo Elías; Rodríguez Lozano, Francisco Javier; Forner, Leopoldo; Biología Celular e Histología
    The purpose of this study was to evaluate the diffusion capacity and the biological effects of different bleaching products on human dental pulp stem cells (hDPSCs). The bleaching gel was applied for 90, 30 or 15 min to enamel/dentine discs that adapted in an artificial chamber. The diffusion of hydrogen peroxide (HP) was analysed by fluorometry and the diffusion products were applied to hDPSCs. Cell viability, cell migration and cell morphology assays were performed using the eluates of diffusion products. Finally, cell apoptosis and the expression of mesenchymal stem cell markers were analysed by flow cytometry. Statistical analysis was performed using analysis of variance and Kruskal–Wallis or Mann–Whitney tests ( < 0.05). Significant reductions of approximately 95% in cell viability were observed for the 3 x 15 min groups (p < 0.001), while 1 x 30 min of PerfectBleach and 1 x 90 min of PolaNight resulted in reductions of 50% and 60% in cell viability, respectively (p < 0.001). Similar results were obtained in the migration assay. Moreover, the 3 x 15 min group was associated with cell morphology alterations and reductions of >70% in cell live. Finally, hDPSCs maintained their mesenchymal phenotype in all conditions. Similar concentrations of carbamide peroxide (CP) and HP in different commercial products exhibited different biological effects on hDPSCs.
  • Thumbnail Image
    Publication
    Open Access
    The importance of diffusion in the microbial world
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 2004) Gacto Fernández, Mariano José; Vicente Soler, Jerónima; Cansado Vizoso, José; Soto, Teresa; Genética y Microbiología; Facultad de Biología
    Una característica destacable de los procariotas es su amplia distribución actual. Los microorganismos aparecieron en la Tierra antes que otros sistemas biológicos, y es posible su continuidad tras la desaparición de otras formas vivientes. Este hecho sugiere que su persistencia descansa en leyes fisicoquímicas simples que deben ser muy estables. El presente trabajo plantea algunas consideraciones teóricas relacionadas con el pequeño tamaño de los microorganismos para destacar que la difusión constituye a microescala un parámetro importante al que el mundo microbiano debe gran parte de su éxito. Debido a su dependencia de la difusión, los procariotas deben presentar necesariamente un pequeño tamaño que no limita, sin embargo, su eficacia metabólica.
  • Thumbnail Image
    Publication
    Restricted
    In vitro study of the antibacterial properties and microbial colonization susceptibility of four self-etching adhesives used in orthodontics
    (Oxford University Press, 2013-05-29) Jacobo, Carmen; Torrella, Francisco; Bravo González, Luis Alberto; Ortiz Ruiz, Antonio José; Vicente, Ascensión; Dermatología, Estomatología, Radiología y Medicina Física
    OBJECTIVES: 1. To determine the in vitro antibacterial effectiveness of the orthodontic bonding Transbond XT (3M Unitek) and four self-etching adhesives with possible use in orthodontic bonding (Clearfil Protect Bond, CPB; Clearfil Self-etching Bond, CSB; Transbond Plus Self-Etching Primer, TSEP; iBond) against Streptococcus mutans and Lactobacillus gasseri in order to compare that capacity among the adhesives and with respect to Transbond XT; 2. To determine the bacterial adhesion capacity of the above mentioned microorganisms to the tested adhesives. MATERIALS AND METHODS: The inhibitory effects of the adhesives against S. mutans and L. gasseri were examined using the agar diffusion method with Whatman No.1 5mm disks loaded with 15 μl of adhesive, UV polymerized, layered on previously inoculated BHI and MRS plates incubated microaerobically for 48 hours at 37 degree C. Data were analysed with Kruskal–Wallis (P < 0.05) and Mann–Whitney tests, applying the Bonferroni correction (P < 0.003). Bacterial adhesion was studied with scanning electron microscopy. RESULTS: Only CPB and iBond produced a clear growth inhibition halo against S. mutans and L. gasseri (P < 0.0001). iBond was the only tested product to which the bacteria adhere profusely, particularly S. mutans. CONCLUSIONS: CPB has shown antimicrobial properties in vitro, and, provided the limitations of an in vitro study, the use of this self-etching adhesive may contribute to reduce microbial decalcification, making the use of this self-etching adhesive an attractive option for bracket bonding.
  • Thumbnail Image
    Publication
    Open Access
    Investigating comproportionation in multielectron transfers via UV–visible spectroelectrochemistry: the electroreduction of anthraquinone-2-sulfonate in aqueous media
    (ACS Publications, 2022-08-22) Romay García, Luis; González Sánchez, Joaquín; Molina Gómez, Ángela; Laborda Ochando, Eduardo; Química Física; Facultad de Química
    UV–vis spectroelectrochemistry is assessed as a tool for the diagnosis and quantitative in situ investigation of the incidence of comproportionation in multielectron transfer processes. Thus, the sensitivity of the limiting current chronoabsorptometric signals related to the different redox states to the comproportionation kinetics is studied theoretically for different working modes (normal and parallel light beam arrangements) and mass transport regimes (from semi-infinite to thin layer diffusion). The theoretical results are applied to the spectroelectrochemical study of the two-electron reduction of the anthraquinone-2-sulfonate in alkaline aqueous solution, tuning the thermodynamic favorability of the comproportionation reaction through the electrolyte cation. The quantitative analysis of the experimental results reveals the occurrence of comproportionation in the three media examined, showing different kinetics depending on the cationic species in solution.
  • Thumbnail Image
    Publication
    Open Access
    La página web del archivo histórico del Instituto Luce: un instrumento de difusión cinematográfica.
    (Murcia, Universidad de Murcia, Servicio de Publicaciones, 2007) Torrado Morales, Susana; Facultad de Comunicación y Documentación
    Es sabido que las tareas de un archivo audiovisual son la recuperación, conservación, el tratamiento y la difusión de las imágenes que contiene; sin embargo, así como las tres primeras han sido tratadas en profundidad, la cuarta siempre ha tenido una menor envergadura. Gracias a las nuevas tecnologías y fundamentalmente a la digitalización de los documentos que componen sus archivos se ha comenzado a difundir a través de Internet fragmentos de filmes e incluso filmografías completas para deleite de la sociedad. Éste es el caso del Instituto Luce, hasta el momento, el único archivo que posee todos sus fondos cinematográficos catalogados accesibles por Internet de una manera gratuita. En este texto se realiza un estudio de la página web del archivo histórico como sucursal virtual y verdadera pantalla de difusión para toda aquella persona que acceda a su fondo audiovisual.
  • Thumbnail Image
    Publication
    Open Access
    Strategic Corporate Social Responsibility Orientation : from gathering information to reporting initiatives
    (Universidad de Murcia, Servicio de Publicaciones, 2022) Gallardo-Vázquez, Dolores; Valdez Juárez, Luis Enrique
    Corporate social responsibility (CSR) strategies have become an important research topic in recent years as they can generate numerous benefits for organizations, especially when an adequate market orientation (MO) has been defined. In this sense, several research questions arise: do companies have enough CSR information to implement appropriate strategies? Does the information that they have gathered allow them to define a complete set of CSR activities (response) based on the triple bottom line approach? And, once they have carried out their initiatives, do these companies ensure adequate dissemination of the results to stakeholders?. In order to answer the above questions, this study sought to examine companies’ CSR orientation from a MO perspective. Working with data on a sample of 165 firms in Spain, during January 15th and February 15th, 2017, structural equation modeling was used to test a set of research hypotheses. The results reveal an important link between information, response, and diffusion and help extend the MO strategy concept. CSR information has a positive, direct influence on the development of initiatives covering three dimensions (economic, social and environmental). In addition, a direct relationship exists between the development of social and environmental initiatives and CSR disclosure. This research’s findings contribute to the literature on interest groups and business sustainability. Also, they confirm that the development of social and environmental initiatives contributes positively to CSR dissemination and to the generation of competitive advantages. This way, collecting CSR information constitutes a valuable asset. With respect to the limitations of the study, the answers reflected each SME leader’s subjective opinion, the variables’ measurement was dealt with through reflective models using the PLS technique based on variance and only Spanish companies already oriented toward CSR participated in the study.