MICROSTRUCTURAL ANALYSIS OF THE INTERFACE BETWEEN SOME SUPERALLOYS AND COMPOSITE/CERAMIC MATERIALS

The clinical success of aesthetic ceramic fused to metal or composite resin bonded to metal restorations depends on the quality and strength of composite/ceramic bonding. To investigate the ceramic and composite surface adhesion to the surface of the alloys, samples were prepared by using the metallographic techniques and then were analyzed by Scanning Electron Microscopy (SEM). We studied a total of four samples of superalloys, denoted S1, S2, S3, and S4. Each of these was treated with: Vita ceramic powders, Noritake ceramic powders, Premise Indirect composite and an indigenous composite C1. At a magnification level of x1500, the adherence between the layers and the surface irregularities of the layers that improve the adherence could be properly observed. It is worth noting that after the sample preparation procedure, samples S1, S2 and S4 were damaged, the only sample remaining in a good condition was sample S3

MICROSTRUCTURAL ANALYSIS OF THE INTERFACE BETWEEN SOME SUPERALLOYS AND COMPOSITE/CERAMIC MATERIALS

The clinical success of aesthetic ceramic fused to metal or composite resin bonded to metal restorations depends on the quality and strength of composite/ceramic bonding. To investigate the ceramic and composite surface adhesion to the surface of the alloys, samples were prepared by using the metallographic techniques and then were analyzed by Scanning Electron Microscopy (SEM). We studied a total of four samples of superalloys, denoted S1, S2, S3, and S4. Each of these was treated with: Vita ceramic powders, Noritake ceramic powders, Premise Indirect composite and an indigenous composite C1. At a magnification level of x1500, the adherence between the layers and the surface irregularities of the layers that improve the adherence could be properly observed. It is worth noting that after the sample preparation procedure, samples S1, S2 and S4 were damaged, the only sample remaining in a good condition was sample S3

RESIN TYPE INFLUENCE ON MOULDED PARTS FINAL DIMENSIONS

Silicone rubber moulding is a perfect solution to fill the gap between rapid prototyping and prototyping injection moulding. Silicone moulds reproduce the tiniest of details, so the quality of the pattern is critical; they are also a fast and affordable solution for functional prototypes and low volume production. A experimental method using vacuum casting of resin parts in flexible moulds is presented in this paper. During the experimental investigations technological features of casted material, volume of air traps, optimal working parameters and dimensional accuracy of the manufactured parts were studied. Based on these results, the corrective coefficients applicable to CAD dimensions to fabricate the master models by SLS were determined

Fuzzy Logic-Based Driving Decision for an Omnidirectional Mobile Robot Using a Simulink Dynamic Model

This scientific paper presents the development and validation process of a dynamic model in Simulink used for decision-making regarding the locomotion and driving type of autonomous omnidirectional mobile platforms. Unlike traditional approaches relying on differential equations, this study uses Simulink’s block-based diagrams, offering a simpler and efficient development process. Importantly, the dynamic model accounts for friction forces, a critical factor for energy monitoring. The model’s validation is conducted experimentally, ensuring its accuracy and reliability. This paper formulates mathematical models for both conventional and Mecanum wheel configurations, facilitating energy-efficient driving strategies. By decomposing resistive forces into inertial and frictional components using the Jacobian matrix, this study accurately simulates electrical current consumption during robot motion. Through fuzzy decision algorithms utilizing parameters such as energy consumption, travel time, precision, and desired maneuverability, this paper proposes a method for determining the optimal locomotion mode for mobile platforms with Mecanum wheels. Overall, this research brings a new contribution to the field of mobile robotics by providing a comprehensive framework for dynamic modeling and it offers the possibility to drive omnidirectional robots in an energy-efficient manner

Mid‐term comparison of new‐onset AHRE between His bundle and left bundle branch area pacing in patients with AV block

Abstract Background Atrial high‐rate episodes (AHRE) detected by cardiac implanted electronic devices are known markers for adverse cardiac events. Previous studies have shown that the incidence of new‐onset AHREs in patients with right ventricular pacing reaches 50%. At the same time, His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) were associated with significantly fewer AHRE. This study aimed to compare the incidence of new‐onset AHRE between HBP and LBBAP in patients with atrioventricular block and no history of atrial fibrillation. Methods One hundred and forty‐two patients, fifty‐nine with HBP and eighty‐three with LBBAP for advanced atrioventricular block, were prospectively followed for new‐onset AHRE. Results The mean follow‐up period was 624 ± 148.6 days for the HBP patients and 663.4 ± 157.4 days for the LBBAP patients. New‐onset AHRE was encountered in 8 of 59 patients (13.5%) with HBP and 14 of 83 (16.8%) with LBBAP (hazard ratio—0.91, log rank p = .84). In the multivariate Cox regression model, HBP and LBBAP had similar predictive values, while only age and diabetes mellitus were significantly associated with new‐onset AHRE occurrence. Conclusion HBP and LBBAP were associated with a similar incidence of device‐detected new‐onset AHRE during a medium‐term follow‐up period in patients with atrioventricular block and no history of atrial fibrillation

Mechanical and structural properties of composites made from recycled and virgin polyethylene terephthalate (PET) and metal chip or mesh wire

Although polyethylene terephthalate (PET) is a champion of recycling, intense research is being done to find new solutions for using recycled plastic. This study aims to characterize the mechanical andstructural properties (SEM- scanning electron microscopy) of products made from recycled metal swarf or mesh wire with recycled plastic (PET) in comparison with virgin plastic. Samples manufactured from virgin and recycled PET are made by pressing and high temperature. The loss of mechanical properties ofproducts made from recycled plastic is a major drawback that influences their use. SEM images confirm that the dispersion and distribution of the PET phase is not very uniform. By addition of virgin plastic in various compositions with recycled plastic, processing parameters and mechanical properties can be optimized

Mechanical and structural properties of composites made from recycled and virgin polyethylene terephthalate (PET) and metal chip or mesh wire

Although polyethylene terephthalate (PET) is a champion of recycling, intense research is being done to find new solutions for using recycled plastic. This study aims to characterize the mechanical andstructural properties (SEM- scanning electron microscopy) of products made from recycled metal swarf or mesh wire with recycled plastic (PET) in comparison with virgin plastic. Samples manufactured from virgin and recycled PET are made by pressing and high temperature. The loss of mechanical properties ofproducts made from recycled plastic is a major drawback that influences their use. SEM images confirm that the dispersion and distribution of the PET phase is not very uniform. By addition of virgin plastic in various compositions with recycled plastic, processing parameters and mechanical properties can be optimized.</jats:p

Gelatin-Based Liver Phantoms for Training Purposes:A Cookbook Approach

Background: Patients with liver pathology benefit from image-guided interventions. Training for interventional procedures is recommended to be performed on liver phantoms until a basic proficiency is reached. In the last 40 years, several attempts have been made to develop materials to mimic the imaging characteristics of the human liver in order to create liver phantoms. There is still a lack of accessible, reproducible and cost-effective soft liver phantoms for image-guided procedure training. Methods: Starting from a CT-scan DICOM file, we created a 3D-printed liver mold using InVesalius (Centro de Tecnologia da informação Renato Archer CTI, InVesalius 3 open-source software, Campinas, Brazil) for segmentation, Autodesk Fusion 360 with Netfabb (Autodesk software company, Fusion 360 2.0.19426 with Autodesk Netfabb Premium 2023.0 64-Bit Edition, San Francisco, CA, USA) for 3D modeling and Stratasys Fortus 380 mc 3D printer (Stratasys 3D printing company, Fortus 380 mc 3D printer, Minneapolis, MN, USA). Using the 3D-printed mold, we created 14 gelatin-based liver phantoms with 14 different recipes, using water, cast sugar and dehydrated gelatin, 32% fat bovine milk cream with intravenous lipid solution and technical alcohol in different amounts. We tested all these phantoms as well as ex vivo pig liver and human normal, fatty and cirrhotic liver by measuring the elasticity, shear wave speed, ultrasound attenuation, CT-scan density, MRI signal intensity and fracture force. We assessed the results of the testing performed, as well as the optical appearance on ultrasound, CT and MRI, in order to find the best recipe for gelatin-based phantoms for image-guided procedure training. Results: After the assessment of all phantom recipes, we selected as the best recipe for transparent phantoms one with 14 g of gelatin/100 mL water and for opaque phantom, the recipes with 25% cream. Conclusions: These liver gelatin-based phantom recipes are an inexpensive, reproducible and accessible alternative for training in image-guided and diagnostic procedures and will meet most requirements for valuable training.</p

Mobile Robots—AHP-Based Actuation Solution Selection and Comparison between Mecanum Wheel Drive and Differential Drive with Regard to Dynamic Loads

Mobile robots are increasingly used in industrial applications. There are many constructive solutions for mobile robots using various variants of actuation and control. The proposed work presents a low-cost variant of a mobile robot equipped with Mecanum wheels, which uses brushed DC motors, controlled by the PWM method as the actuation solution. In the first part, a multicriteria analysis based on the AHP method was performed for the selection of the actuation solution. Then, using the software tools Simscape Multibody, Matlab, and Simulink, models were developed that allowed the simulation of the operation of the proposed robot, based both on its kinematics and dynamics. Using these models, both the Mecanum wheel drive version and the differential drive version were studied by means of simulation. The simulations mainly aimed at identifying the way the currents vary through the wheel drive motors, in order to find methods to reduce them. The values obtained by the simulation were later compared with those obtained experimentally, and the corresponding conclusions with regard to the accuracy of the models were drawn