SOUTHERN JOURNAL OF SCIENCES

Dentistry is a part of medicine, where various polymer materials were used for the first time. Many factors forced researchers to find more stable, versatile, and hygienic materials for the manufacture of dental products. It is important to note that the search for the ideal polymer dental material is still ongoing. This is because modern polymers, in some cases, do not meet the specified requirements for chemical, physical, strength, and elasticproperties. Based on the data on the method of creating and using silicone material for the base of the removable prosthesis "Gossil", an improved silicone material for two-layer dentures "Silep" was developed, as well as a special primer for better connection of the lining with the rigid acrylic base of the prosthesis. To evaluate the most suitable compound, materials were tested for several parameters, such as tensile strength, elongation, and shore hardness. In addition to selecting a suitable material for modification, the selection and testing of an adhesive that allows the chemical bonding of the acrylate surface to the siloxane surface were carried out. 

Background: This paper presents a straightforward and intuitive method for interactive 3D reconstruction and Direct Linear Transformation (DLT) camera calibration using a single image of a structured scene with known object dimensions. The method relies on manual registration of pairs of points on both the image and the terrain, allowing for precise alignment and calibration. Aim: By utilizing this method, users can easily reconstruct 3D scenes and calibrate cameras without the need for complex algorithms or extensive computational resources. Our approach offers a user-friendly solution for 3D reconstruction and camera calibration, making it accessible to a wider audience and applicable in a range of fields such as computer vision, augmented reality, and virtual reality. Methods: This work primarily focuses on the determination of the projection matrix, which plays a crucial role in mapping 3D points onto a 2D image plane. The projection matrix encapsulates both the intrinsic parameters of the camera (such as focal length and optical center) and the extrinsic parameters (such as camera position and orientation in the world coordinate system). By accurately determining the projection matrix, we can effectively project 3D points onto the 2D image plane, enabling tasks like 3D reconstruction, camera localization, and augmented reality applications. Results: We present experimental results obtained from testing the method on an image of a known object, demonstrating its effectiveness and accuracy in producing realistic 3D reconstructions. Discussion: The method's reliance on manual registration of point pairs allows for precise alignment and calibration without the need for complex algorithms or extensive computational resources. This user-friendly approach makes 3D reconstruction and camera calibration accessible to a wider audience and applicable in various fields. Conclusions: Overall, our approach offers a practical and accessible solution for 3D reconstruction and camera calibration, expanding the potential applications in computer vision, augmented reality, and virtual reality.

Background: The recovery of any valuable component from dolomite as a double carbonate mineral depends on its dissolution efficiency. Aim: This study aimed to optimize and provide a simplified novel approach to the kinetics of dolomite dissolution in sulphuric acid solution using the Box-Behnken experimental design. Methods: The dolomite sample was dissolved in a sulphuric acid solution at seventeen different experimental conditions. The residue containing impurities was removed via filtration, while precipitation was carried out at the optimum conditions. Results and Discussion: The relationship between the independent and dependent variables best fits into the two-factor interaction model with a coefficient of determination of 0.9492, adjusted R² of 0.9187, and predicted R² of 0.7514. The total residual sum of 3x10^-13 and adequate precision of 18.769 show that the predicted dissolution efficiency is much closer to the experimental values. The analysis of variance revealed that the individual effect of acid concentration, temperature, and dissolution time all positively contribute to the dissolution. The interactive effect of acid concentration with temperature and the interactive effect of temperature with dissolution time also positively influences the dissolution efficiency. Following the dissolution of dolomite in sulphuric acid, a white precipitate was formed at room temperature, which dissolved back at a temperature of 70 oC, agitation speed of 900 revolutions per minute, and within 10 minutes. A predictive approach using a two-factor interactive model was applied to generate the kinetic data. Conclusions: The established model equation is suitable for predicting dolomite dissolution in sulphuric acid. The application of the shrinking core model to the generated data shows that the reaction between dolomite and sulphuric acid is film diffusion control with a first-order reaction (0.6587) and activation energy of 27.5 KJmol-1k-1.