Magnetic Chitosan for the Removal of Sulfamethoxazole from Tertiary Wastewaters.

Magnetic chitosan nanoparticles, synthesized by in situ precipitation, have been used as adsorbents to remove sulfamethoxazole (SMX), a sulfonamide antibiotic dangerous due to its capacity to enter ecosystems. The adsorption of SMX has been carried out in the presence of tertiary wastewaters from a depuration plant to obtain more realistic results. The effect of pH on the adsorption capacity significantly changed when carrying out the experiments in the presence of wastewater. This change has been explained while taking into account the charge properties of both the antibiotic and the magnetic chitosan. The composition of wastewaters has been characterized and discussed as regards its effect on the adsorption capacity of the magnetic chitosan. The models of Elovich and Freundlich have been selected to describe the adsorption kinetics and the adsorption isotherms, respectively. The analysis of these models has suggested that the adsorption mechanism is based on strong chemical interactions between the SMX and the magnetic chitosan, leading to the formation of an SMX multilayer.

Mechanical and microstructural characterization of titanium gr.5 parts produced by different manufacturing routes.

Since a few decades, the aircraft industry has shifted its preference for metal parts to titanium and its alloys, such as the high-strength titanium grade 5 alloy. Because of titanium grade 5 limited formability at ambient temperature, forming operations on this material requires high temperatures. In these conditions, a peculiar microstructure evolves as a result of the heating and deformation cycles, which has a significant impact on formability and product quality. On the other hand, additive manufacturing technologies, such as selective laser melting and electron beam melting, are increasingly being used and are replacing more traditional approaches such as machining and forging. Fundamental part characteristics such as mechanical and microstructural properties, geometric accuracy, and surface quality strongly depend on the selection of the manufacturing method. The authors of this paper seek to identify the strengths and limitations imposed by the intrinsic characteristics of different manufacturing alternatives for the production of parts of aeronautical significance, providing guidelines for the choice of the most appropriate manufacturing route for a given application and part design.

Effect of Implant Surface Roughness and Macro- and Micro-Structural Composition on Wear and Metal Particles Released.

BACKGROUND: Considerations about implant surface wear and metal particles released during implant placement have been reported. However, little is known about implant surface macro- and microstructural components, which can influence these events. The aim of this research was to investigate accurately the surface morphology and chemical composition of commercially available dental implants, by means of multivariate and multidimensional statistical analysis, in order to predict their effect on wear onset and particle release during implant placement. METHODS: The implant surface characterization (roughness, texture) was carried out through Confocal Microscopy and SEM-EDS analysis; the quantitative surface quality variables (amplitude and hybrid roughness parameters) were statistically analyzed through post hoc Bonferroni's test for pair comparisons. RESULTS: The parameters used by discriminant analysis evidenced several differences in terms of implant surface roughness between the examined fixtures. In relation to the observed surface quality, some of the investigated implants showed the presence of residuals due to the industrial surface treatments. CONCLUSIONS: Many structural components of the dental implant surface can influence the wear onset and particles released during the implant placement.

Clinical Influence of Micromorphological Structure of Dental Implant Bone Drills.

BACKGROUND: Considerations about heat generation, wear, and corrosion due to some macrostructural bur components (e.g., cutting lips, rake angle, flute, and helix angle) have been widely reported. However, little is known about how the microstructural components of the implant drill surface can influence the implant drill lifetime and clinical performance. AIM: To investigate accurately the surface morphology of surgical bone drill, by means of multivariate and multidimensional statistical analysis, in order to assess roughness parameters able to predict the evolution of tribological phenomena linked to heat development, wear, and corrosion occurring in clinical use. MATERIALS AND METHODS: The surfaces of implant drills approximately 2.0mm in diameter made by five manufacturers were examined by means of confocal microscope with white light laser interferometry, obtaining several surface roughness parameters. Statistical multivariate analysis based on discriminant analysis showed, for each cut-off, the parameters which discriminate the manufacturers. RESULTS: The microstructural parameters used by discriminant analysis evidenced several differences in terms of drill surface roughness between the five manufacturers. CONCLUSIONS: The observed surface roughness difference of drills is able to predict a different durability and clinical performance especially in heat generation and wear onset.