Studying the causes of postharvest fruit loss is important to avoid reduction of quality and quantity for the consumer due, for example, to the influence of frequent impacts from vibrations during transportation. In this sense, this study evaluates the storage quality of ‘Palmer’ mangoes after being subjected to different simulated road transport vibrations. Vibration was simulated from the analysis of the profile of the frequencies generated in road transport of fruit, determined in a tractor trailer. ‘Palmer’ mangoes stored after vibration stress wereevaluated for: mass loss, absorbance difference index (IAD), peel and pulp browning index (BI), pulp firmness, soluble solids content, and titratable acidity. The development of a vibration machine made it possible to satisfactorily simulate specific vibration frequencies. Vibration stress during simulated transport led to accelerated weight loss, decreased pulp firmness, and peel browning in ‘Palmer’ mangoes.

The process of manufacturing drug delivery systems (DDSs) by fused deposition modeling (FDM) with 3D printing requires the availability of a polymeric filament containing the drug of interest. This filament is fused in the printer heating system and used to print polymer/drug volumetric parts. Polymers with pH-dependent solubility are widely known in the literature for their controlled release and drug dissolution-enhancing properties, biocompatibility, and variety of release profiles. Given these characteristics, the study of pH-responsive 3D printing filaments appears as a potential alternative for the development of new 3D printing functional materials for healthcare area applications. In this sense, this work aimed at the preparation and characterization of pH-dependent filaments of the Eudragit E 100 copolymer (E100) containing the model drug Amlodipine (Aml) for potential application in the manufacturing of DDSs by 3D printing. The E100/Aml filaments with two distinct drug concentrations were produced by hot-melt extrusion at 105 °C. The posterior chemical protonation treatment of the filaments for 60 min provided a significant improvement in their flexibility. Microstructural analysis (SEM, XRD, FTIR, and DLS) and thermal studies by DSC proved the feasibility of producing the filaments by hot-melt extrusion without the degradation of their constituent materials. The in vitro dissolution profiles of the E100/Aml samples were evaluated in simulated gastric and intestinal fluids. The facilitated solubility of the polymer in an acidic medium (pH = 1.2) was preserved in the filament form, with rapid and reproducible drug release from the polymer matrix. The saturation of the drug concentration in the medium occurred after 30 min of testing for E100/Aml models. A customized 3D part with geometry and fill control was also printed from E100/Aml filaments as proof of concept.

Resumo Este trabalho tem como objetivo avaliar a durabilidade do gesso com a adição de hidrorrepelente quando submetido ao envelhecimento acelerado. Para isso foram utilizados gesso e hidrorrepelente de massa. Foi fixada a relação água/gesso em 0,7 e utilizados os teores de 0,2% e 0,4% de hidrorrepelente em relação à massa de gesso. O gesso de referência (sem hidrorrepelente) e o gesso contendo hidrorrepelente de massa foram avaliados na idade “zero” e após 10 e 20 ciclos de secagem e molhagem. Foram realizados ensaios de dureza, resistência à compressão, absorção por imersão total, absorção por capilaridade e análise de MEV e EDS. Aos 20 ciclos de envelhecimento acelerado, houve redução das propriedades mecânicas; em contrapartida, manteve-se uma redução considerável, tanto da absorção por imersão, quanto da absorção por capilaridade nos corpos de prova contendo o hidrorrepelente em comparação aos corpos de prova de referência. Em relação à microestrutura, mesmo aos 20 ciclos, foi possível identificar a presença do hidrorrepelente formando um “filme” sobre os cristais de gesso, tendo sido identificado um percentual maior do hidrorrepelente na região mais superficial do corpo de prova. Tais resultados mostram a eficácia do hidrorrepelente como barreira de proteção diante do envelhecimento acelerado.

Fused deposition modeling (FDM) 3D printing is characterized as a technology for manufacturing three-dimensional objects through the deposition of successive layers of molten material onto a build platform, based on a user-defined design. The development of non-conventional polymer-based filaments incorporating carbon-based semiconducting materials represents an open field of research in both academia and industry, with applications in emerging areas such as supercapacitors, photocatalysts, and sensors. This paper investigates the development of non-conventional filaments for FDM 3D printing based on polylactic acid (PLA) and reduced graphene oxide (rGO) nanoparticles, aiming to obtain electrically conductive properties for emerging applications in nanoelectronics. The composites were prepared by dispersing rGO in a PLA solution using chloroform as solvent, followed by controlled evaporation, oven drying, and hot melt extrusion of filaments with different rGO mass concentrations (0%–15% w w ⁻¹ ), all showing good reproducibility. Sample characterization was carried out using scanning electron microscopy, x-ray diffraction, differential scanning calorimetry, mechanical strength tests, and electrical resistivity measurements. The results revealed a typical electrical percolation behavior with a reduction in resistivity by 6 orders of magnitude (∼200 MΩ cm to ∼300 Ω cm), with a percolation threshold around 3.95% rGO. The rate of change in resistivity became less evident for the samples containing 9.1% or more of rGO, while filament processability was maintained up to 15% rGO, above which excessive stiffness was observed. Additional tests demonstrated the feasibility of printing three-dimensional structures with low electrical resistance, with potential for use in personalized functional devices.

Este trabalho tem como objetivo avaliar a influência de hidrorrepelentes nas propriedades do gesso beta de fundição. No estudo foram testados dois tipos de hidrorrepelentes: um hidrorrepelente de massa (um aditivo hidrofugante) e outro de superfície (um impermeabilizante). O aditivo foi adicionado nos teores de 0,2% e 0,4%, em relação a massa de gesso. O impermeabilizante foi aplicação superficialmente nos corpos de prova de gesso em duas e quatro demãos. Em todas as mistura avaliadas a relação água/gesso foi fixada em 0,7. Foram avaliadas as propriedades calor de hidratação, tempo de pega, dureza, resistência à compressão, absorção de água por imersão total e por capilaridade. Em geral, observou-se que a ação dos hidrorrepelentes testados diminuindo a capacidade de absorção de água, sem interferir significativamente nas demais propriedades, quando comparado com o tratamento de referência.

Poly (methyl methacrylate) is a polymer widely used in various biomedical applications. In orthopedics, this polymer may be used as a structural reinforcement in fracture, aiding bone regeneration. To avoid fracture contamination, surgeons may add a certain homogeneously amount of antimicrobial to the Poly (methyl methacrylate). To prevent thermal necrosis during polymerization, which can reach up to 100° C, cooling techniques are used, to ensure the cells integrity during the process. Despite the great importance of Poly (methyl methacrylate) as a biomaterial, there is still a lack of information on the mechanical properties of this polymer, especially when there is modifications on Poly (methyl methacrylate) composition and its preparation temperature. This work aims to evaluate the influence of the addition of Gentamicin Sulfate and application of cooling technique on the mechanical behavior of Poly (methyl methacrylate) in three commercial types. For this, the mechanical tests of compression, bending and torsion were performed. With these tests it was found that, despite the reduction of the mechanical resistance of Poly (methyl methacrylate) with the cooling technique and antimicrobial addition, the polymer can still be safely used as bone cement. DOI:https://doi.org/10.56238/uniknowindevolp-133