Evaluation of direct light processing for the fabrication of bioactive ceramic scaffolds: Effect of pore/strut size on manufacturability and mechanical performance

Bioactive ceramic scaffolds for bone regeneration consisting of a three-dimensional mesh of interpenetrating struts with square section were fabricated via Digital Light Processing (DLP). The ability of the technique to manufacture 3D porous structures from β-tricalcium phosphate (β-TCP) powders with different dimensions of struts and pores was evaluated, identifying the possibilities and limitations of the manufacturing process. Small pore sizes were found to seriously complicate the elimination of excess slurry from the scaffold’s innermost pores. The effect of the strut/pore size on the mechanical performance of the scaffolds under compressive stresses was also evaluated, but no significant influence was found. Under compressive stresses, the structures resulted weaker when tested perpendicularly to the printing plane due to interlayer shear failure. Interlayer superficial grooves are proposed as potential failure-controlling defects, which could also explain the lack of a Weibull size effect on the mechanical strength of the fabricated DLP scaffolds.     

QoS metrics-in-the-loop for endowing runtime self-adaptation to robotic software architectures

Multimedia Tools and Applications - The design of robots capable of operating autonomously in changing and unstructured environments, requires using complex software architectures in which,...     

Pulsed Electromagnetic Field Stimulation in Osteogenesis and Chondrogenesis: Signaling Pathways and Therapeutic Implications

Mesenchymal stem cells (MSCs) are the main cell players in tissue repair and thanks to their self-renewal and multi-lineage differentiation capabilities, they gained significant attention as cell source for tissue engineering (TE) approaches aimed at restoring bone and cartilage defects. Despite significant progress, their therapeutic application remains debated: the TE construct often fails to completely restore the biomechanical properties of the native tissue, leading to poor clinical outcomes in the long term. Pulsed electromagnetic fields (PEMFs) are currently used as a safe and non-invasive treatment to enhance bone healing and to provide joint protection. PEMFs enhance both osteogenic and chondrogenic differentiation of MSCs. Here, we provide extensive review of the signaling pathways modulated by PEMFs during MSCs osteogenic and chondrogenic differentiation. Particular attention has been given to the PEMF-mediated activation of the adenosine signaling and their regulation of the inflammatory response as key player in TE approaches. Overall, the application of PEMFs in tissue repair is foreseen: (1) in vitro: to improve the functional and mechanical properties of the engineered construct; (2) in vivo: (i) to favor graft integration, (ii) to control the local inflammatory response, and (iii) to foster tissue repair from both implanted and resident MSCs cells.     

Efficient sunlight and UV photocatalytic degradation of Methyl Orange,Methylene Blue and Rhodamine B,using Citrus×paradisi synthesized SnO2 semiconductor nanoparticles

In this work, tin dioxide (SnO2) Nanoparticles (NPs) were synthesized through green synthesis, using Citrus × paradisi extract as a stabilizing (capping). The extract concentrations used were 1, 2 and 4% in relation to the aqueous solution. The resulting SnO2 NPs were used for the degradation of Methyl Orange (MO), Methylene Blue (MB) and Rhodamine B (RhB), under both solar and UV radiation. The NPs were characterized via Attenuated Total Reflectance Infrared Spectroscopy (ATR-IR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM-SAED), the Brunauer-Emmett-Teller (BET) theory, Ultraviolet to Visible spectroscopy (UV–Vis), and Photoluminescence spectroscopy (PL); while the photocatalytic degradation was evaluated using UV-VIS. The results showed that the Citrus × paradisi extract is a good medium for the formation of SnO2 NPs. These NPs presented quasi-spherical morphology, particle sizes of 4–8 nm, with a rutile phase crystalline structure, and with banned gap of 2.69 at 3.28 eV. The NPs had excellent photocatalytic properties under solar radiation, degrading 100% of the OM in 180 min. Furthermore, under UV radiation, 100% degradation of the three dyes was achieved in a short time; 20 min for MO, and 60 min for MB and RhB. Therefore, green synthesis is a feasible medium for the formation of SnO2 NPs with good photocatalytic properties.     

Effect of processing on the microbiological quality and safety of chicken carcasses at slaughterhouse

Microbiological contamination of chicken meat depends on the conditions under which the animals are reared, slaughtered and processed. The aim of this study was to determine the influence of farm origin and processing stages at slaughterhouse on the microbial safety and quality of chicken. Samples of chicken carcasses from three different farms were taken from a slaughterhouse. Mesophiles, Escherichia coli, coagulase positive Staphylococcci counts, presence of Listeria monocytogenes,Campylobacter and Salmonella were determined at five sampling points: after defeathering, after evisceration, after washing, after chilling and after cutting. Chilling reduced log numbers of mesophiles, coagulase positive Staphylococci and E. coli by 0.85, 1.52 and 2.2 log units, respectively. Salmonella was not detected after chilling. High prevalence of Campylobacter spp was observed at all the stages ranging between 84% and 100%. L. monocytogenes was not detected in chicken carcasses after defeathering. However, it was detected after evisceration and after washing and chilling. The most critical stage for L. monocytogenes contamination was the portioning operation, the prevalence in breast and legs being 88% and 84%, respectively.     

Effects of Ce Doping on the Photocatalytic and Electrochemical Performance of Nickel Hydroxide Nanostructures

Topics in Catalysis - Ni(OH)2 doped with cerium cations was synthesized by a hydrothermal method and its electrochemical, photoelectrochemical and photocatalytic behavior was determined by the...     

Environmental impact estimation of ceramic lightweight aggregates production starting from residues

Within a circular economy approach, this study investigates the environmental impact of lightweight aggregates (LWAs) produced starting from different mixes of different clays with brewery sludge and cattle bone flour ash (CBA), used as poring and fertilizing agents, respectively. The environmental impact was evaluated by means of release tests, insulation capacity, carbon footprint (CFP), and particulate matter emission during pellet firing. Release tests representative of LWAs realistic application showed very high release of phosphate and satisfactory release of potassium. The thermal insulation of the LWAs was tested by thermal imaging camera and resulted highly variable depending on the composition, with the mix containing CBA performing best. This latter composition leads also to the smallest CO₂ equivalent emission, due to the calorific power of CBA, allowing lower consumption of fossil fuels during the LWA production. Finally, total particulate emissions during the thermal treatment resulted similar in terms of mass for all mixes, while differences in terms of particle morphology and composition occurred. Samples containing residue resulted with a quite good release behavior, CFP, and insulation properties, but higher emission of particles, particularly when glass is added.     

Selective Photo-epoxidation of (R)-(+)- and (S)-(−)-Limonene by Chiral and Non-Chiral Dioxo-Mo(VI) Complexes Anchored on TiO2-Nanotubes

Topics in Catalysis - Selective epoxidation of the (R) and (S) isomers of limonene by dioxomolybdenum(VI) complexes anchored covalently on TiO2 nanotubes using UV–Vis light and O2 as the...