1,721,121 research outputs found
Las Ciencias Sociales en el diseño Curricular de la Escuela Primaria De Adultos: Un debate pendiente
No full textFil: Miola, Marta Haydee. Universidad Nacional de Luján; Argentina.Este trabajo se centra en el Diseño Curricular destinado para las escuelas de nivel primario de Adultos, haciendo hincapié en la enseñanza y los contenidos implicados en la transmisión de las Ciencias Sociales. Se plantea que esos contenidos deberían tener relación con la realidad social de los alumnos, muchas veces condicionada por la pobreza y también qué tipo de modificaciones se realizaron desde el retorno de la Democracia y la posterior Reforma Educativa con su contexto neoliberal. Por último, se ocupa de la Formación Docente para esta área, los cuales deben ser críticos y concientes para proporcionarle a sus alumnos Adultos herramientas y conocimientos para mejorar su calidad de vida
New PMMA bone cement added with ferrimagnetic bioactive glass for hyperthermia treatment
No full textINTRODUCTION
The design of a composite material like Polymethylmethacrylate (PMMA) bone cement loaded with a bioactive and ferrimagnetic glass-ceramic is very useful against the development and proliferation of bone tumors. This biomaterial produces heat by magnetic hysteresis loss due to presence of magnetite (Fe3O4) inside the glass-ceramic phase1 and so it can be used in hyperthermia treatment. Moreover, the bioactive component of the glass-ceramic confers osteointegration property at the material. The aim of the present work is the synthesis and characterization of a composite cement in which the disperse phase is a glass ceramic (SC45) with magnetic property, embedded in a polymeric (PMMA) matrix.
EXPERIMENTAL METHODS
The SC45 powders, (see1 for the chemical composition) sieved below 20 micron, were mixed in different amounts (10, 15, 20% wt) with the polymeric solid phase of a commercial bone cement (Palamed®MV). The mixed powders and the liquid monomer were manually mixed for two minutes and subsequently put inside a mold, obtaining the composite cements. P10, P15, P20. Furthermore commercial cements were prepared as control. The characterizations were developed for all formulations proposed as described below.
Mechanical testing of cement samples
The compressive strength of the cement were evaluated according to standard ISO 5833 procedure. For each formulation 6 samples were tested.
Calorimetric measurements
The heat generation was measured with an induction furnace at fixed frequency and alternate electromagnetic field. The samples were placed in a test tube containing 10 ml of distilled water. The increase of temperature that occurred following the heat transfer from the magnetic phase of the composite to water was measured with a thermocouple.
SEM and EDS analysis before and after bioactivity test
SEM-EDS analyses were carried out to evaluate the morphology and composition of the samples.
RESULTS AND DISCUSSION
The compression strength of the composites depends from the amount of glass-ceramic phase; nevertheless the reached values satisfy the ISO requirements ( >70 MPa).
Calorimetric tests show a maximum increasing temperature of 40°C that respect the limit imposed by hyperthermia therapy.
CONCLUSION
The preliminary experimental tests demonstrated a good mechanical properties and a good osteointegration. The calorimetric test evidenced a range of temperature adapted to biological environment.
REFERENCES
1. O. Bretcanu et al. Journal of Magnetism and Magnetic Materials, 305 (2006) 529-533.
ACKNOWLEDGMENTS
The authors would like to thank to the MIUR Grant for Young researchers 2012.
SESSION
Materials and Devices for Emerging Clinical Challenge
Bioactive and antibacterial glass powders doped with copper by ion-exchange in aqueous solutions
Full text linkIn this work, two bioactive glass powders (SBA2 and SBA3) were doped with Cu by means of the ion-exchange technique in aqueous solution. SBA2 glass was subjected to the ion-exchange process by using different Cu salts (copper(II) nitrate, chloride, acetate, and sulphate) and concentrations. Structural (X-ray diffraction-XRD), morphological (Scanning Electron Microscopy-SEM), and compositional (Energy Dispersion Spectrometry-EDS) analyses evidenced the formation of crystalline phases for glasses ion-exchanged in copper(II) nitrate and chloride solutions; while the ion-exchange in copper(II) acetate solutions lead to the incorporation of higher Cu amount than the ion-exchange in copper(II) sulphate solutions. For this reason, the antibacterial test (inhibition halo towards S. aureus) was performed on SBA2 powders ion-exchanged in copper(II) acetate solutions and evidenced a limited antibacterial effect. A second glass composition (SBA3) was developed to allow a greater incorporation of Cu in the glass surface; SBA3 powders were ion-exchanged in copper(II) acetate solutions (0.01 M and 0.05 M). Cu-doped SBA3 powders showed an amorphous structure; morphological analysis evidenced a rougher surface for Cu-doped powders in comparison to the undoped glass. EDS and X-ray photoelectron spectroscopy (XPS) confirmed the Cu introduction as Cu(II) ions. Bioactivity test in simulated body fluid (SBF) showed that Cu introduction did not alter the bioactive behaviour of the glass. Finally, inhibition halo test towards S. aureus evidenced a good antimicrobial effect for glass powders ion-exchanged in copper(II) acetate solutions 0.05 M
Antibacterial and bioactive composite bone cements containing surface silver-doped glass particles
No full textA bioactive silica-based glass powder (SBA2) was doped with silver (Ag(+)) ions by means of an ion-exchange process. Scanning electron microscopy (SEM), energy dispersion spectrometry (EDS) and x-ray diffraction (XRD) evidenced that the glass powder was enriched with Ag(+) ions. However, a small amount of Ag2CO3 precipitated with increased Ag concentrations in the exchange solution. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Ag-SBA2 towards Staphylococcus aureus were also evaluated and were respectively 0.05 mg ml(-1) and 0.2 mg ml(-1). Subsequently, Ag-SBA2 glass was used as filler (30%wt) in a commercial formulation of bone cement (Simplex(TM) P) in order to impart both antibacterial and bioactive properties. The composite bone cement was investigated in terms of morphology (using SEM) and composition (using EDS); the glass powder was well dispersed and exposed on the cement surface. Bioactivity tests in simulated body fluid (SBF) evidenced the precipitation of hydroxyapatite on sample surfaces. Composite cement demonstrated antibacterial properties and a compressive strength comparable to the commercial formulation
On the mechanism of apatite-induced precipitation on 45S5 glass pellets coated with a natural-derived polymer
No full textMagnetic Bioactive Glass Ceramics for Bone Healing and Hyperthermic Treatment of Solid Tumors
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