Search Results (9,443)

This study investigates 3D extrusion bioinks for cartilage tissue engineering by characterizing the physical properties of 3D-printed scaffolds containing varying alginate and polyvinyl alcohol (PVA) concentrations. We systematically investigated the effects of increasing PVA and alginate concentrations on swelling, degradation, and the elastic modulus of printed hydrogels. Swelling decreased significantly with increased PVA concentrations, while degradation rates rose with higher PVA concentrations, underscoring the role of PVA in modulating hydrogel matrix stability. The highest elastic modulus value was achieved with a composite of 5% PVA and 20% alginate, reaching 0.22 MPa, which approaches that of native cartilage. These findings demonstrate that adjusting PVA and alginate concentrations enables the development of bioinks with tailored physical and mechanical properties, supporting their potential use in cartilage tissue engineering and other biomedical applications. Full article

This study aimed to prepare ultrasonically modified peanut protein–guar gum composite emulsion gels for 3D printing. The composition of the composite emulsion gels was determined in single-factor and orthogonal experiments. The results revealed that the optimal composite emulsion gels consisted of 6% peanut protein, 50% oil and 0.2% guar gum. After crushing pretreatment for 45 s, the printing deviation of the composite emulsion gels was reduced to 8.58 ± 0.20%. Moreover, after ultrasonic treatment (200 W for 20 min) of peanut proteins, the obtained composite emulsion gels presented the highest yield stress, hardness and G’ values, as well as a denser and more homogeneous microstructure. After protein ultrasonic modification (200 W or 600 W for 20 min), the printing accuracy and self-supporting properties of the composite emulsion gels for printing complex shapes significantly improved, which was attributed to their stronger textural and rheological properties; however, ultrasonically modified peanut protein–guar gum composite emulsion gels were not suitable for printing products with smooth surfaces. Full article

The relevance of creating specialized computer programs that convert a virtual 3D model of an object into machine code (G-code) for controlling the process of 3D printing products from wire raw materials is substantiated. It is shown that for wire-based additive technologies, a fundamentally important requirement is to ensure the continuity of the surfacing trajectory within one section. A method for determining a continuous surfacing trajectory is proposed, the implementation of which requires two stages: performing a numerical analysis of a two-dimensional region with boundary conditions describing this section; and running a heuristic algorithm for the movement of the surfacing head, in which the direction of movement is selected based on the results of the analysis. The procedure for setting boundary conditions and an algorithm for numerically solving the boundary value problem of determining the field of the “height” function for each section are described. The principles of operation of the heuristic algorithm for selecting the direction of head movement based on the calculated height field and continuous determination of the proximity of adjacent layers and section boundaries are disclosed. An analysis of the algorithm operation is carried out using a section with holes as an example, and the potential of using numerical methods to calculate the change in the temperature field during the surfacing process is shown. Full article

This study explores the fatigue behavior and fracture mechanisms of TC11 titanium alloy formed by laser metal deposition (LMD) and subjected to double annealing. The research focuses on how the alloy’s unique microstructure, consisting of alternating equiaxed and columnar crystals, influences its fatigue performance. The microstructure’s basket-like α’ phase, made up of both plate-shaped and needle-like structures, leads to variations in crack growth behavior, as shown in the relationship between the crack growth rate and the stress intensity. An analysis of slip patterns reveals that equiaxed crystals undergo more frequent deformation, accelerating crack propagation compared to the more evenly distributed deformation in columnar crystals. These findings suggest a new approach for improving the fatigue resistance of 3D-printed titanium alloys by optimizing their microstructure. This study provides valuable insights for enhancing material toughness and extending the lifespan of titanium alloys in applications such as aerospace and biomedical engineering. Full article

Background. Major aortopulmonary collateral arteries (MAPCAs) are rare remnants of pulmonary circulation embryological development usually associated with complex congenital anomalies of the right ventricular outflow tract and pulmonary arteries. Effective management requires surgical unifocalization of MAPCAs and native pulmonary arteries (NPAs). Traditional imaging may lack the spatial clarity needed for precise surgical planning. Aim. This study evaluated the feasibility of integrating three-dimensional (3D) printing and virtual reality (VR) into preoperative planning to improve surgical precision, team communication, and parental understanding. In a prospective cohort study, nine infants undergoing MAPCA unifocalization were included. Four patients underwent conventional imaging-based planning (control), while five were additionally assessed using VR and 3D-printed models (intervention). The outcomes measured included operative times, team confidence, collaboration, and parental satisfaction. Statistical analysis was performed using standard tests. Results. The intervention group had shorter operative and cardiopulmonary bypass times compared to the control group. Intraoperative complications were absent in the VR/3D group but occurred in the control group. Medical staff in the VR/3D group reported significantly improved understanding of anatomy, surgical preparedness, and team collaboration (p < 0.05). Parents also expressed higher satisfaction, with better comprehension of their child’s anatomy and surgical plan. Conclusions. VR and 3D printing enhanced preoperative planning, surgical precision, and communication, proving valuable for complex congenital heart surgery. These technologies offer promising potential to improve clinical outcomes and patient–family experiences, meriting further investigation in larger studies. Full article

Background/Objectives: Pediatric facial fractures present unique challenges due to the anatomical, physiological, and developmental differences in children’s facial structures. The growing facial bones in children complicate diagnosis and treatment. This review explores the advancements and complexities in managing pediatric facial fractures, focusing on innovations in diagnosis, treatment strategies, and multidisciplinary care. Methods: A narrative review was conducted, synthesizing data from English-language articles published between 2001 and 2024. Relevant studies were identified through databases such as PubMed, Scopus, Lilacs, Embase, and SciELO using keywords related to pediatric facial fractures. This narrative review focuses on anatomical challenges, advancements in diagnostic techniques, treatment approaches, and the role of interdisciplinary teams in management. Results: Key findings highlight advancements in imaging technologies, including three-dimensional computed tomography (3D CT) and magnetic resonance imaging (MRI), which have improved fracture diagnosis and preoperative planning. Minimally invasive techniques and bioresorbable implants have revolutionized treatment, reducing trauma and enhancing recovery. The integration of multidisciplinary teams, including pediatricians, psychologists, and speech therapists, has become crucial in addressing both the physical and emotional needs of patients. Emerging technologies such as 3D printing and computer-assisted navigation are shaping future treatment approaches. Conclusions: The management of pediatric facial fractures has significantly advanced due to innovations in imaging, surgical techniques, and the growing importance of interdisciplinary care. Despite these improvements, long-term follow-up remains critical to monitor potential complications. Ongoing research and collaboration are essential to refine treatment strategies and improve long-term outcomes for pediatric patients with facial trauma. Full article

Bionic bioceramic scaffolds are essential for achieving excellent implant properties and biocompatible behavior. In this study, inspired by the microstructure of natural bone, bionic hydroxyapatite (HAp) ceramic scaffolds with different structures (body-centered cubic (BCC), face-centered cubic (FCC), and gyroid Triply Periodic Minimal Surfaces (TPMSs)) and porosities (80 vol.%, 60 vol.%, and 40 vol.%) were designed, 3D-printed, and characterized. The effects of structure and porosity on the morphology, mechanical properties, and in vitro biocompatibility properties of the HAp scaffolds were studied and compared with each other. Interestingly, the HAp scaffold with a porosity of 80 vol.% and a TPMS structure had the best combination of compressive strength and in vitro biocompatibility, and demonstrated a great biomedical application potential for bone repair. We hope this study can provide a reference for the application and development of HAp scaffolds in the field of bone repair engineering. Full article

Based on the basic theoretical framework of the Bi-directional Evolutionary Structural Optimization method (BESO) and the Solid Isotropic Material with Penalization method (SIMP), this paper presents a multiscale topology optimization method for concurrently optimizing the sandwich structure at the macro level and the core layer at the micro level. The types of optimizations are divided into macro and micro concurrent topology optimization (MM), macro and micro gradient concurrent topology optimization (MMG), and macro and micro layered gradient concurrent topology optimization (MMLG). In order to compare the multiscale optimization method with the traditional macroscopic optimization method, the sandwich simply supported beam is illustrated as a numerical example to demonstrate the functionalities and superiorities of the proposed method. Moreover, several samples are printed through micro-nano 3D printing technology, and then the static three-point bending experiments and the numerical simulations are carried out. The mechanical properties of the optimized structures in terms of deformation modes, load-bearing capacity, and energy absorption characteristics are compared and analyzed in detail. Finally, the multiscale optimization methods are extended to the design of 2D sandwich cantilever beams and 3D sandwich fully clamped beams. Full article

In this paper, a novel dual-slot-fed dielectric resonator antenna (DRA) with rectangular and irregular elements, designed for 5G wireless applications, is presented. The DRA achieves wideband capability by combining the resonant modes of the rectangular and irregular DRA elements, which is a less common feature in conventional designs. A frequency ratio adjustment technique, based on the concept of inductive de-loading, is uniquely proposed for the independent frequency adjustment of the irregular DRA. Unlike traditional methods, an equivalent circuit presentation was developed to interpret the impedance characteristics of single-element DRAs, and to provide new insights into the presence of inductive de-loading from a circuit perspective. For verification, a dual-slot-fed prototype was fabricated through digital light processing (DLP)-based 3D printing technology, with the aim of customizable design and low-cost fabrication. The measured and simulated results of reflection coefficients and radiation patterns showed good agreements, with a measured bandwidth of 51.6% (2.96–5.02 GHz), effectively covering the desired 5G n77–n79 (3.3–5.0 GHz) frequency bands. Full article

Post-processing, and particularly the dry electropolishing process, is essential for improving the surface quality of 3D-printed Ti6Al4V samples, with specific emphasis on reducing roughness over extended polishing times while preserving mechanical properties. Reducing surface roughness enhances the reliability of hardness measurements and improves the consistency of elastic modulus measurements, as prolonged polishing time stabilizes the full width at half maximum values, thereby minimizing variability due to uniaxial indentation. This stability is crucial for maintaining the structural integrity and uniformity of mechanical properties, facilitating better performance and reliability in biomedical applications. Additionally, under service-like working conditions, solid electrolyte particles undergo dehydration due to the Joule effect, introducing a dynamic aspect to the system as the particle structure degrades with thermal cycling. EDX cross-sectional analysis reveals that TiO₂ informs the particle’s surface, with an oxygen-to-titanium ratio that confirms the oxide’s composition. This TiO₂ oxide layer demonstrates the progressive surface oxidation occurring under the post-processing process, further modifying the particle’s surface chemistry. This dual effect of roughness reduction and controlled surface chemistry highlights the role of dry electropolishing in enhancing the functional lifespan and mechanical reliability of Ti6Al4V components. Full article

Based on a combination of hexagonal honeycomb and re-entrant honeycomb cells, the concept of novel hybrid cell structures was developed. Experimental studies and numerical analyses of the behaviour of the analysed structures under in-plane compression in two compression directions were carried out. Explicit finite element analyses with an explicit integration scheme, incorporating plastic deformation and ductile damage evolution models, were employed to analyse the entire deformation process, including plastic and damage stages. Good agreement was obtained between the results of the numerical analyses and the experimental studies. Full article

The effect of tilapia skin gelatin properties on the characteristics of high internal phase emulsions (HIPEs) and the quality of 3D printing remains unidentified. In this work, HIPEs were constructed by gelatin with various properties that were obtained by heat treatment. The results indicated that the gelatin undergoes degradation gradually with an increase in heating intensity. The highest values of intrinsic fluorescence intensity, surface hydrophobicity, and emulsification were obtained when the heating time was 5 h. The gel strength and hardness of gelatin hydrogels were negatively correlated with heat treatment temperature. HIPEs constructed by gelatin extracted at 70 °C demonstrated a suitable material for 3D printing. The storage modulus (G′) and viscosity of HIPEs exhibited a similar tendency as the gel strength of gelatin. The microstructure of HIPEs revealed that gelatin established a gel network around oil droplets, and the higher G′ of HIPEs corresponded to a more compact network structure. This study elucidated the correlation between the structure and properties of gelatin, offering essential insights for the formulation of HIPEs by natural gelatin, which is suitable for applications across several domains. Full article

Background: Head and neck reconstruction following ablative surgery results in alterations to maxillofacial anatomy and function. These postoperative changes complicate dental rehabilitation. Methods: An innovative modular, stackable guide system for immediate dental rehabilitation during mandibular reconstruction is presented. The virtual surgical planning was performed in Materialise Innovation Suite v26 and Blender 3.6 with the Blenderfordental add-on. The surgical guides and models were designed and manufactured at the point of care. Results: The duration of the surgery was 9 h and 35 min. Good implant stability (>35 Ncm) and a stable occlusion were achieved. After 9 months of follow-up, the occlusion remained stable, and a mouth opening of 25 mm was registered. The dental implants showed no signs of peri-implant bone loss. Superposition of the preoperative planning and postoperative position of the fibula parts resulted in an average difference of 0.70 mm (range: −1.9 mm; 5.4 mm). Conclusions: The in-house developed stackable guide system resulted in a predictive workflow and accurate results. The preoperative virtual surgical planning was time-consuming and required extensive CAD/CAM and surgical expertise. The addition of fully guided implant placement to this stackable guide system would be beneficial. More research with longer follow-ups is necessary to validate these results. Full article

The use of 3D-printed gene-activated bone grafts represents a highly promising approach in the fields of dentistry and orthopedics. Bioresorbable poly-lactic-co-glycolic acid (PLGA) scaffolds, infused with adenoviral constructs that carry osteoinductive factor genes, may provide an effective alternative to existing bone grafts for the reconstruction of extensive bone defects. This study aims to develop and investigate the properties of 3D scaffolds composed of PLGA and adenoviral constructs carrying the BMP2 gene (Ad-BMP2), both in vitro and in vivo. The elastic modulus of the disk-shaped PLGA scaffolds created using a specialized 3D printer was determined by compressive testing in both axial and radial directions. In vitro cytocompatibility was assessed using adipose-derived stem cells (ADSCs). The ability of Ad-BMP2 to transduce cells was evaluated. The osteoinductive and biocompatible properties of the scaffolds were also assessed in vivo. The Young’s modulus of the 3D-printed PLGA scaffolds exhibited comparable values in both axial and radial compression directions, measuring 3.4 ± 0.7 MPa for axial and 3.17 ± 1.4 MPa for radial compression. The scaffolds promoted cell adhesion and had no cytotoxic effect on ADSCs. Ad-BMP2 successfully transduced the cells and induced osteogenic differentiation in vitro. In vivo studies demonstrated that the 3D-printed PLGA scaffolds had osteoinductive properties, promoting bone formation within the scaffold filaments as well as at the center of a critical calvarial bone defect. Full article