National Nuclear Energy Commission

About: National Nuclear Energy Commission is a government organization based out in Rio de Janeiro, Brazil. It is known for research contribution in the topics: Dosimetry & Laser. The organization has 3816 authors who have published 4694 publications receiving 59951 citations.

Optimization of a Linear Superconducting Levitation System

Abstract: The Laboratory for Applied Superconductivity of the Federal University of Rio de Janeiro (LASUP) has been developing a superconducting magnetic levitation urban train named MagLev-Cobra. It is a kind of light rail vehicle where the conventional wheel-rail track is substituted by a rail of Ne-Fe-B magnets and carbon steel interacting with superconductor bulks installed in the vehicle to promote levitation. The main cost of this levitation system is the magnetic rail. Therefore, any improvement in the shape and configuration of magnets and iron has a significant budgetary impact. In this paper, the optimizations carried out with the feasible direction interior point algorithm, extensive search, and genetic algorithm of magnetic rails are presented. The objective is to find the geometry that minimizes the total cost, for a given levitation force, considering some practical restrictions. The levitation force restriction is calculated using a finite-element method. During the optimization process, the superconductor null permeability model is used. Finally, the results are checked with the Bean model and verified experimentally. Measurements of the levitation force and the field mapped over the magnetic rails are presented. Significant reduction of soft and hard ferromagnetic materials was reached.

CdTe quantum dots conjugated to concanavalin A as potential fluorescent molecular probes for saccharides detection in Candida albicans.

Abstract: Semiconductor colloidal quantum dots (QDs) have been applied in biological analysis due to their unique optical properties and their versatility to be conjugated to biomolecules, such as lectins and antibodies, acquiring specificity to label a variety of targets. Concanavalin A (Con A) lectin binds specifically to α-d-mannose and α-d-glucose regions of saccharides that are usually expressed on membranes of mammalian cells and on cell walls of microbials. Candida albicans is the most common fungal opportunistic pathogen present in humans. Therefore, in this work, this fungus was chosen as a model for understanding cells and biofilm-forming organisms. Here, we report an efficient bioconjugation process to bind CdTe (Cadmium Telluride) QDs to Con A, and applied the bioconjugates to label saccharide structures on the cellular surface of C. albicans suspensions and biofilms. By accomplishing hemagglutination experiments and circular dichroism, we observed that the Con A structure and biochemical properties were preserved after the bioconjugation. Fluorescence microscopy images of yeasts and hyphae cells, as well as biofilms, incubated with QDs-(Con A) showed a bright orange fluorescence profile, indicating that the cell walls were specifically labeled. Furthermore, flow cytometry measurements confirmed that over 93% of the yeast cells were successfully labeled by QD-(Con A) complex. In contrast, non-conjugated QDs or QDs-(inhibited Con A) do not label any kind of biological system tested, indicating that the bioconjugation was specific and efficient. The staining pattern of the cells and biofilms demonstrate that QDs were effectively bioconjugated to Con A with specific labeling of saccharide-rich structures on C. albicans. Consequently, this work opens new possibilities to monitor glucose and mannose molecules through fluorescence techniques, which can help to optimize phototherapy protocols for this kind of fungus.