Dental caries remains a significant health issue in pediatric populations, necessitating effective non-invasive treatments that promote remineralization and inhibit demineralization. This study investigates the efficacy of poly-gamma-glutamic acid (PGGA), a natural biodegradable polypeptide, in preventing mineral loss and enhancing enamel repair in deciduous teeth. Study utilizing a pH cycling model mimicking oral environment showed that artificial caries lesions were treated with 1% and 2% PGGA with/without hydroxyapatite and compared to sodium fluoride (NaF) treatments. It was found that 2% PGGA markedly increased calcium uptake and integrated mineral recovery to a greater extent than some NaF concentrations. In-depth remineralization was evidenced by a cross-sectional microhardness study. These results advocate PGGA as an effective biomimetic material in the treatment of early childhood caries and a potential substitute for traditional fluoride therapies.
Recycling polymeric waste is a key component of the circular economy, aiming to reduce environmental impact and resource consumption. However, polymeric blends obtained from mixed recycled plastics often exhibit variable mechanical properties due to differences in composition and compatibility among constituent polymers. This study investigates the flexural behavior of a recycled polymeric blend to assess its suitability for applications requiring moderate bending loads. Samples consisting of approximately 70% polyethylene (LDPE and HDPE), 20% polypropylene, and minor fractions of ABS, PET, and PA6/6 were fabricated by a two-stage extrusion-molding process without washing or compatibilization. Three-point bending tests were conducted in accordance with SR ISO 178:2019 using an Instron 5982 universal testing machine at five crosshead speeds (10-1000 mm/min). Mechanical parameters-including maximum force, flexural stress, Young's modulus, strain, and absorbed energy-were determined. Differential scanning calorimetry (DSC) was employed to confirm blend composition and homogeneity. The recycled blend exhibited flexural stress values between 14 and 19 MPa and a flexural modulus ranging from 0.61 to 0.83 GPa, with minimal dependence on test rate. The absorbed energy at 50 mm displacement varied between 14 J and 18.5 J, and no cracking or brittle fracture occurred at any test rate. The material displayed good elastic recovery after the test and a narrow standard deviation across all mechanical parameters, indicating reproducibility and homogeneity. The results demonstrate that the recycled polymeric blend possesses stable and repeatable mechanical performance under bending, comparable to conventional HDPE/LDPE or PP-based materials. Its low rate sensitivity and energy absorption capacity support its potential use in non-structural or moderately loaded components (up to similar to 12 MPa), providing a viable, eco-friendly alternative to virgin polymers or wood-based materials in various applications.
The consideration of additive manufacturing as a production method leads to a new approach with other elements of manufacturing technology systems. In this research article, a robot-assisted manufacturing method is considered in order to increase the efficiency and accuracy of the 3D printing process. There are two possibilities of 3D printing when a robot arm is used: a conventional one (plane-to-plane printing) and a non-planar/continuous one when a 3-dimensional trajectory is used. The aim of the research is to establish the differences between the mechanical properties and precision of 3D printed parts using these two methods of 3D printing. This paper presents a methodology used in control software for both the robotic arm and the extruder, converting 3D models into executable robotic instructions, and performing accurate hardware calibration. The material selected for the experiments was ONYX, which is a composite material that includes carbon fiber, which has better properties with respect to metal, namely, low weight, better mechanical strength, rigid parts under repeated loads, better adaptability for customization, and suitability for on-demand production. These properties are required in the automotive and aerospace industries. In the experiments carried out, several parameters were taken into account, such as UV radiation, humidity, nozzle diameter, and temperature (printing speed is constant). The samples were subjected to tensile tests, and the results obtained are discussed in the paper.
The effective treatment of skin wounds remains a challenge, largely due to complications from bacterial infections. In this study, polyvinylidene fluoride (PVDF)/polyethylene oxide (PEO) nanofibrous membranes incorporated with azithromycin (AZ) were fabricated via electrospinning as a novel antibacterial wound dressing. The morphology, chemical composition, and wettability of the nanofibers were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and contact angle analysis, respectively. Antibacterial evaluations demonstrated that increasing AZ concentration significantly enhanced the inhibition zones, confirming strong antibacterial performance. Furthermore, in vivo experiments on Staphylococcus aureus-infected rat wounds revealed that the PVDF/PEO/AZ membranes effectively suppressed suppuration and maintained a cleaner wound surface. These results highlight the potential of AZ-loaded PVDF/PEO nanofiber dressings as promising candidates for advanced wound care, combining biocompatibility, structural integrity, and sustained antibacterial activity.
Background: Thyroid cancer remains the most common endocrine malignancy, and a subset of patients exhibit aggressive invasion and recurrence. Conventional two-dimensional culture models fail to replicate the three-dimensional (3D) tumor microenvironment, underscoring the need for biomimetic scaffolds to study invasion and therapy response. Methods: GelMA/SA double-network hydrogels with different ratios (3:1, 1:1, 1:3) were fabricated by sequential photocrosslinking and ionic crosslinking. Their swelling, degradation, and mechanical properties were characterized, and microstructures were examined by scanning electron microscopy. Human papillary thyroid carcinoma cell lines (TPC-1 and BCPAP) were encapsulated to evaluate viability, morphology, and invasive behavior. Results: The hydrogel composition strongly influenced structural and biological performance. SA-rich gels showed excessive swelling, rapid degradation, and poor pore formation, while GelMA-rich gels were stable but less porous. The intermediate 1:1 formulation exhibited balanced swelling and degradation, uniform pores, and enhanced tensile and compressive strength. Encapsulated cells in the 1:1 gels displayed robust viability, extended pseudopodia, and maintained expression of invasion-related markers (N-cadherin, MMP-9). Conclusion: The GelMA: SA = 1:1 double-network hydrogel provides the most favorable microenvironment for thyroid cancer cell invasion modeling, combining porosity, stability, and bioactivity. This 3D platform offers a reliable tool for mechanistic studies and therapeutic evaluation in thyroid cancer.
