Synthesis and characterization of fluorescent PVA/pvac-rodhamine microspheres

Fluorescent polymeric microspheres are used in a wide range of biomedical and technological applications, including blood flow determination, screening, flow visualization, flow tracing, medical imaging, fluorescence microscopy and flow cytometry among others. Rhodamine 6G (R6G) is a lipophilic cationic dye, which is among the most stable organic fluorophores, and with a high quantum yield in fluorescence (absorption and emission) in the visible range (500-600 nm). It is mainly applied in laser technology, and also in fluorescent bioimage. In this work we present an efficient synthesis route to obtain Polyvinyl Alcohol/Polyvinyl Acetate (PVA/PVAc) spherical microparticles containing Rhodamine 6G in a concentration sufficient to exploit their fluorescent properties. The synthesis method comprises the suspension polymerization of Vinyl acetate (VAc) monomer in the presence of Rhodamine, followed by saponification. Microspheres loaded with 1.9% w / w of Rhodamine 6G were obtained. They presented good sphericity and a size distribution in the range of 20 to 1550 microns. The fluorescence intensity of the microspheres was measured by UV-Vis and fluorescence spectroscopy, and detected using an image-based experimental setup, respectively. The results obtained with these methodologies showed that our microspheres exhibit fluorescence and that they are quite detectable in water flows. However, the response of UV-Visible fluorescence and absorbance was affected by the presence of the PVA / PVAc polymer matrix.Fil: Ambrosio Tellez, Luisa Fernanda. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Verón, María Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Silin, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Prado, Miguel Oscar. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Thermodynamic behavior of the Mg–Co–H system: The effect of hydrogen cycling

Thermodynamic properties of the Mg–Co–H system were investigated using equilibrium pressure measurements. Experimental determination of absorption and desorption pressure-composition isotherms (PICs) was carried out in the temperature range of 250–425 °C, using as starting material a 2Mg–Co mixture milled under argon and Mg2CoH5 produced by reactive ball milling of the 2MgH2–Co mixture. It was found that the cycling affects the PCIs shape and the total hydrogen storage capacity. XRPD analysis of the samples at different stage of the absorption PCIs reveals that the plateau at low hydrogen pressure is associated with the formation of Mg6Co2H11 and the plateau at higher hydrogen pressure corresponds to Mg2CoH5 formation. In addition, an intermediate plateau is also observed at 300 and 350 °C, which was related with the formation of MgH2 from MgCo intermetallic.Fil: Verón, María Gisela. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gennari, Fabiana Cristina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Study of changes in the chemical composition of a glass ionomer using the PIXE technique

En el presente trabajo se estudia el efecto de bebidas de consumo habitual como café, mate, té y agua mineral en la composición química de la superfície de un ionómero de vidrio comercial. Las muestras de ionómero se prepararon según las indicaciones del fabricante; se colocaron en las infusiones y se estacionaron en estufa de cultivo a 36 °C en el rango de 21 horas hasta 33 días. La evolución de la composición química a diferentes tiempos de almacenamiento se estudió mediante la técnica de Emisión de Rayos X inducida por Protones (PIXE). En todos los medios, excepto agua mineral, a tiempos largos se determinó la pérdida de Al, Si y Na, esto sugiere la disolución parcial de un aluminosilicato de Na. El perfil de concentración de Al y Si fue diferente en todos los medios, pero la relación Al:Si se mantuvo cercana a la unidad en todos los casos. El F se liberó asociado con Na en agua mineral, mientras que en el resto de bebidas su perfil de concentración infiere la formación de compuestros fluorados de Ca y La. Simultáneamente se observó la incorporación de Mn, Mg y Fe en la superficie del ionómero vítreo, no reportada anteriormente en la literatura.In the present work, the effect of commonly consumed beverages such as coffee, mate, tea and mineral water on the surface chemical composition of a commercial glass ionomer is studied. Ionomer samples were prepared according to the manufacturer; they were placed within infusions and stationed on culture stove at 36 ° C in the range of 21 hours to 33 days. The evolution of the chemical composition at different storage times was studied by Proton Induced X-Ray Emission (PIXE) technique. In all media except mineral water, to long times, the loss of Al, Si and Na was determined, suggesting the partial dissolution of Na aluminumsilicate. The concentration profile of Al and Si were different in every way, but the ratio Al: Si remained close to unity in all cases. The F was released associated with Na in mineral water, while in the rest of the beverages its concentration profile infers the formation of fluorinated compounds of Ca and La. Simultaneously, the adsorption of Mn, Mg and Fe to the glass ionomer surface was observed, not previously reported in the literature.Fil: Verón, María Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Suarez, Sergio Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Prado, Miguel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentin

La relevancia de la información contable en el mercado de capitales

n.d.Verón, Carmen; Facultad de Ciencias Económicas y Estadística; Universidad Nacional de Rosario; Argentina

Effective synthesis of Mg2CoH5 by reactive mechanical milling and its hydrogen sorption behavior after cycling

Mg2CoH5 was synthesized by reactive mechanical milling (RMM) under hydrogen atmosphere (0.5 MPa) from 2MgH2eCo and 3MgH2eCo mixtures, with a yield >80%. The microstructure, structure and thermal behavior of the phases formed during the processing were investigated by transmission electron microscopy, X-ray diffraction and differential scanning calorimetry. Kinetic properties of the reaction with hydrogen of the 2MgH2eCo and 3MgH2eCo mixtures after RMM were evaluated using modified Sievertstype equipment. The 3MgH2eCo mixture showed better properties for storage applications, with its highest rate of hydrogen absorption and desorption at 300 C, its storage capacity of about 3.7 wt% in less than 100 s, and good stability after cycling. Although the starting material presents Mg2CoH5 as majority phase, the cycling leads to disproportion between Mg and Co. We obtained a mixture of Mg2CoH5, Mg6Co2H11 and MgH2 hydrides, as well as other phases such as Co and/or Mg, depending on experimental conditions.Fil: Verón, María Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energia Atomica. Centro Atomico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Condo, Adriana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energia Atomica. Centro Atomico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; ArgentinaFil: Gennari, Fabiana Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comision Nacional de Energia Atomica. Centro Atomico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Area de Energía Nuclear. Instituto Balseiro; Argentina. Universidad Nacional de Cuyo; Argentin

Study of the effect of common infusions on glass ionomers using the PIXE and RBS techniques

The effect of four commonly consumed beverages as mineral water, coffee, tea and mate tea on the elemental composition of a commercial glass ionomer was studied using Particle Induced X-ray Emission (PIXE) and Rutherford backscattering (RBS) techniques. We found that after immersion in acidic media, some elements as Al, Si and Na are lost from the glass-ionomer whereas others heavier, as K, Ca and La, increase their concentration at the surface. Although the concentration profiles of Al and Si are different in different media, in all of them the Al:Si ratio was close to unity and remained constant for different periods of immersion in all media. The incorporation of K, Mg and Fe to the surface is found for common infusions while for mineral water the glass-ionomer mainly loses F and Na.The RBS technique showed that immersion in different media produced a modification of the density of the glass ionomer surface layer due to the increment of the concentration of heavier elements at the surface. The thickness of the modified surface layer extends up to 3 µm when the immersion time is seven days and more than 6 µm after 33 days of immersion.Fil: Verón, María Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Pérez, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Suarez, Sergio Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Prado, Miguel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Porous PVA microspheres for Oxytetracycline delivery

Porous PVA microspheres were prepared to investigate their adsorption and release capacity ofoxytetracycline (OTC) in simulated biological fluid (SBF). The highest adsorption capacity of OTC during 2 hours was obtained at pH= 4, being 0.9 mg g-1. The release profile of OTC in SBF from the microspheres showed a burst effect with a cumulative release of 29±4 % within the first thirty minutes due to the immediate release of the OTC adsorbed on the surface of the microspheres, followed by a slower release reaching 41±5% within two hours,which in terms of concentration is equivalent to 4.2 μg/mL, a value close to the minimum inhibitory concentration of pathogens susceptible to OTC in injectable administration methods of therapeutic doses from 10 mg/Kg for farm animals.Fil: Verón, María Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Álvarez Soria, Joaquín. Universidad Nacional de Río Negro. Sede Andina; ArgentinaFil: Pérez, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Prado, Miguel Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentin

Synthesis and mechanical behavior of poly (vinyl alcohol) / poly (vinyl acetate) microspheres

In this work, the effect of an organic solvent (tert-butanol) during the polymerization of vinyl acetate (VAc) on the structural and elastic properties of poly(vinyl alcohol)/poly(vinyl acetate) microspheres fabricated by the suspension polymerization method was investigated. As a result, two types of microspheres were obtained: without tert-butanol (Ms-P) and with tert-butanol (Ms-T), the later was added during the polymerization. For the experimental conditions used in this work, both types of Ms had spherical shape. Also, Ms-P exhibits a size distribution ranging from 10 µm to 1200 µm with an apparent density value ~1.18 ± 0.03 g/cm3, a solid structure and a saponification grade α ~ 0.8. In turn, Ms-T shows a size distribution between 400 and 1900 µm, porous structure, a lower density value ρ ~ 0.87 ± 0.03 g/cm3 and α ~ 0.5. The mechanical tests performed on Ms-P and Ms-T in three different conditions (dry, suspended in distilled water and saline solution) showed Young’s modulus (E) values of 569 ± 162 MPa (dried), 8 ± 9 MPa (distilled water), 11 ± 9 MPa (saline solution) for Ms-P measured up to 30% of deformation. For Ms-T, 242 ± 63 MPa (dried), 0.52 ± 0.08 MPa (distilled water), 0.9 ± 0.5 MPa (saline solution) values were obtained. Thus, we have found that the E values for Ms-T are more than one order of magnitude lower than for Ms-P. Also, it was observed that keeping Ms in an aqueous medium helps decrease the E value. This work shows that the ability to control the structural and elastic properties in Ms employing addition to an organic solvent gives the possibility of tuning its behavior for possible use in the treatment of embolization and chemoembolization.Fil: Ambrosio Tellez, Luisa Fernanda. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; Argentina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Verón, María Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Cardoso, Jorge. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; ArgentinaFil: Prado, Miguel Oscar. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Infrared and Raman spectra of [Re(CN)5NO]3- complex isolated in KCl matrix

We report here the infrared and Raman spectra of [Re(CN)5NO]3- complex as guest diluted in the KCl crystal lattice. According to the chemical analysis, the anion concentration in the KCl host matrix is in excess of 2% (in mole). The solid state Raman spectrum of this complex is reported for the first time. The information obtained from the relative intensities of infrared and Raman bands affords a reexamination of vibration mode assignments. The observed bands splitting may be explained by the interactions of the guest complex with the host lattice, including the ways in which the K+ vacancies are distributed around [Re(CN)5NO]3- to achieve lattice charge neutrality.Fil: Verón, María Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Castañeda Trujillo, Lady Diana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Piro, Oscar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Guida, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Química Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Química Inorgánica "Dr. Pedro J. Aymonino"; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentin

Estudio de los cambios de la composición química de un ionómero vítreo mediante la técnica de PIXE

<p></p><p>ABSTRACT In the present work, the effect of commonly consumed beverages such as coffee, mate, tea and mineral water on the surface chemical composition of a commercial glass ionomer is studied. Ionomer samples were prepared according to the manufacturer; they were placed within infusions and stationed on culture stove at 36 ° C in the range of 21 hours to 33 days. The evolution of the chemical composition at different storage times was studied by Proton Induced X-Ray Emission (PIXE) technique. In all media except mineral water, to long times, the loss of Al, Si and Na was determined, suggesting the partial dissolution of Na aluminumsilicate. The concentration profile of Al and Si were different in every way, but the ratio Al: Si remained close to unity in all cases. The F was released associated with Na in mineral water, while in the rest of the beverages its concentration profile infers the formation of fluorinated compounds of Ca and La. Simultaneously, the adsorption of Mn, Mg and Fe to the glass ionomer surface was observed, not previously reported in the literature.</p><p></p