Microtomography is a powerful non-destructive method that allows the visualization of the internal structure of the object and makes possible to generate internal graphic models of the object. Concrete is a mixture widely used in the construction industry due to the union between its mechanical properties with the low cost for its production. The application of X-ray microtomography in lightweight concrete structures allows the visualization of the layout and formation of existing internal structures. In this work it was possible to identify the presence of ethyl vinyl acetate (EVA) and piaçava fibers in the internal structure of the samples and to classify the high density aggregates according to the ASTM C125-18 standard, as well as to evaluate the influence of the light aggregates in the increasing of the total porosity.
Objective: To compare the agreement of images in white light (WL), fluorescence (FL), and digital radiographs (DR), on the diagnosis and treatment decisions for occlusal caries lesions against a micro-CT gold standard. Material and Methods: Ten extracted third molars, with enamel and/or dentin caries (ICDAS 2-4), were included. Occlusal surface images were acquired with an intraoral camera (SoproLife ® ) in WL and FL modes. DR was obtained using an intraoral X-ray and a semi-direct digital system. A total of 780 images were needed, organized in a template, to be later examined by twenty-six dentists invited to compose the study. The Generalized Estimation Equations model was used to compare the proportions of the correct answers between the three methods and the gold standard. When significant, Bonferroni posthoc test was used to identify differences (α=5%). Results: Most of the examiners were specialists (76.9%) with 14.5 years of experience. All diagnostic methods were similar and showed low agreement (DR 12.7%, WL 16.5%, and FL 16.5%) compared with gold standard caries diagnostic scores. Regarding treatment decisions, mean agreement for all diagnostic methods was higher (43.2%; p<0.001), and among all methods, WL (48.1%) and FL (51.2%) modes performed better than DR (30.4%, p<0.001). Conclusion: SoproLife ® images could help clinicians to propose rational, minimally invasive treatments for occlusal caries lesions.
Brazilian Rainforest is the habitat of many species of the genus Brachycephalus, among them is the pumpkin toadlet, Brachycephalus ephippium. X-ray microcomputed tomography is a nondestructive imaging technique which allows the visualization and analysis of internal microstructures of various samples, and has been applied on the study of these animals, enabling thorough description and characterization of new species. Brachycephalus ephippium is of particular interest for it was the first Brachycephalus species to be discovered, which makes it a common interspecies comparative basis. Cranial morphological landmarks used in biological research are very small (0.1-1mm), hence the effects of voxel size on microCT images can be relevant, and this is what was investigated in this work. Effects of reconstruction voxel size were evaluated in both visual and quantitative perspectives, which showed that an intermediary voxel size could be chosen on similar microCT applications without significant loss of information, but with great processing and storage gain, optimizing the application of the technique in such works.
Concrete is widely used in the world and is the main material for civil construction. Due to its properties, it has different uses such as structural, filling and shielding. The aim of this work is to compare experimental and theoretical mass attenuation coefficient for concrete with different traits and determine the one with the best performance. For this, density, X-ray diffraction, mass attenuation coefficient (experimental with a Cs137 source, simulated by MCNP and theoretical determined with XCOM platform) and compressive strength were determined for three different traits of cement mortar (standardized sand, conventional sand and artificial sand). The X-ray diffraction showed more compounds for artificial sand’s samples. Density showed no significant variation. The samples showed a good agreement for experimental, simulated and theoretical mass attenuation coefficient. Standardized sand’s samples had the best performance for mechanical test, with a compressive strength 47.4% higher than artificial sand’s samples and 38.2% higher than conventional sand’s samples. It is possible to conclude that, since mass attenuation coefficient showed no significant difference, standardized sand’s samples is more indicated to be used for shielding than the others.
Bread is one of the oldest foods of mankind, and among them, the sandwich bread is worldwide known and used. In this study we used the non‐destructive computed microtomography technique (microCT) to evaluate the behavior of bread structure over weeks after the production. In addition, the influence of the storage location of the sandwich bread, we performed a comparative analysis between storage at ambient temperature and refrigerated conditions. The analysis of the reconstructed images shows that the bread suffers loss of structure over the weeks. We also have found that keeping the bread refrigerated loses liquid, drying the bread, and thus increasing the loss of its structure. In addition, the porous structure of the bread was evaluated, and a complete characterization of the microstructural changes was performed over time.
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