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.

Estimative of the Stacking Fault Energy for a FeNi(50/50) Alloy and a 316L Stainless Steel

Abstract: The effect of high energy milling on powders of a FeNi (50/50) alloy and a 316L stainless steel has been evaluated by means of X-Ray Diffraction (XRD). The average microstrain as function of the milling time (1/2h, 1h and 8h) was determined from XRD data. The displacement and broadening of the (XRD) peaks were used for estimate the stacking fault energy (SFE), using the method of Reed and Schramm. It was estimated SFE=79 mJ/m2 for the FeNi (50/50) alloy and SFE=14 mJ/m2 for the 316L stainless steel. The better experimental conditions for determining the SFE by XRD are discussed.

General Expressions for the Magnetic Flux Density Produced by Axially Magnetized Toroidal Permanent Magnets

Abstract: This paper presents analytical-integral expressions which evaluate the magnetic flux density radial and axial components' on- and off-axis of axially magnetized toroidal permanent magnets. The pieces, when used in magnetic electron beam focusing structures called periodic-permanent magnets (PPMs), can be employed in microwave vacuum electronics devices. These expressions can be adapted to computational algorithms, especially those developed based on mathematical commercial codes, aiding the investigation of the effect of magnetic fields on electron beam dynamics. Comparisons between analytical-integral expressions and theoretical and experimental data are also presented and discussed.

Birefringence and second harmonic generation on tendon collagen following red linearly polarized laser irradiation.

Abstract: Regarding the importance of type I collagen in understanding the mechanical properties of a range of tissues, there is still a gap in our knowledge of how proteins perform such work. There is consensus in literature that the mechanical characteristics of a tissue are primarily determined by the organization of its molecules. The purpose of this study was to characterize the organization of non-irradiated and irradiated type I collagen. Irradiation was performed with a linearly polarized HeNe laser (λ = 632.8 nm) and characterization was undertaken using polarized light microscopy to investigate the birefringence and second harmonic generation to analyze nonlinear susceptibility. Rats received laser irradiation (P = 6.0 mW, I = 21.2 mW/cm(2), E ≈ 0.3 J, ED = 1.0 J/cm(2)) on their healthy Achilles tendons, which after were extracted to prepare the specimens. Our results show that irradiated samples present higher birefringence and greater non-linear susceptibility than non-irradiated samples. Under studied conditions, we propose that a red laser with polarization direction aligned in parallel to the tendon long axis promotes further alignment on the ordered healthy collagen fibrils towards the electric field incident. Thus, prospects for biomedical applications for laser polarized radiation on type I collagen are encouraging since it supports greater tissue organization.