Inducing Magnetic Properties with Ferrite Nanoparticles in Resins for Additive Manufacturing.

Additive manufacturing and nanotechnology have been used as fundamental tools for the production of nanostructured parts with magnetic properties, expanding the range of applications in additive processes through tank photopolymerization. Magnetic cobalt ferrite (CoFe2O4) and barium ferrite (BaFe12O19) nanoparticles (NPs) with an average size distribution value (DTEM) of 12 ± 2.95 nm and 37 ± 12.78 nm, respectively, were generated by the hydroxide precipitation method. The dispersion of the NPs in commercial resins (Anycubic Green and IRIX White resin) was achieved through mechanochemical reactions carried out in an agate mortar for 20 min at room temperature, with limited exposure to light. The resulting product of each reaction was placed in amber vials and stored in a box to avoid light exposure. The photopolymerization process was carried out only at low concentrations (% w/w NPs/resin) since high concentrations did not result in the formation of pieces, due to the high refractive index of ferrites. The Raman spectroscopy of the final pieces showed the presence of magnetic NPs without any apparent chemical changes. The electron paramagnetic resonance (EPR) results of the pieces demonstrated that their magnetic properties were maintained and not altered during the photopolymerization. Although significant differences were observed in the dispersion process of the NPs in each piece, we determined that the photopolymerization did not affect the structure and superparamagnetic behavior of ferrite NPs during processing, successfully transferring the magnetic properties to the final 3D-printed piece.

A mixed-methods evaluation of school-based active living programs.

BACKGROUND: School-based programs to combat childhood obesity often lack resources to incorporate strong evaluation components. This paper describes a collaborative evaluation conducted by partners implementing Active Living by Design (ALbD) programs at one Chicago elementary school. PURPOSE: To assess ALbD program outcomes by triangulating various forms of evidence gathered while implementing these programs. METHODS: An exploratory, mixed-methods design was used to collect and analyze data from numerous physical activity initiatives implemented at the school from 2004 to 2009. The researchers triangulated quantitative (student BMI data, student standardized test and discipline data, classroom physical activity logs, and student physical activity knowledge surveys) and qualitative (classroom physical activity logs and open-ended teacher surveys questions) findings to assess outcomes. RESULTS: Students continuously enrolled at this school from Grades 1 through 4, those most exposed to ALbD activities over time, had significantly lower BMI after 4 years, compared with peers who transferred to the school after Grade 1. Student achievement on standardized tests improved between 2004 (prior to initiating ALbD activities) and 2008. Visits to the Disciplinary Office dropped dramatically over the 4-year period. Teacher interviews and surveys and classroom Take 10! Program activity logs revealed that the program was implemented enthusiastically by all grades. The Physical Activity Knowledge Survey revealed a significant increase in physical activity knowledge after instituting these activities. CONCLUSIONS: Collaborative efforts to amass and analyze a variety of data demonstrated the effects of implementing a variety of health promotion activities in one school, documenting the growth of a "culture of health" in that school community.