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.

Investigation of the electrochemical behaviour and surface chemistry of a Ti‐13Nb‐13Zr alloy exposed in MEM cell culture media with and without the addition of H2O2

Abstract: Promoting and understanding the formation of hydroxyapatite (HA) on biocompatible metals in the body is a very important topic of biomaterials research. In this paper, the formation of HA on a near-β Ti-13Nb-13Zr alloy by immersion in minimal essentialmedium(MEM)withandwithouttheadditionofH2O2 hasbeenstudiedusingelectrochemicalmethods,SEMandXPS. The Ti-13Nb-13Zr alloy exhibits passive behaviour over a wide potential range when immersed in MEM, and the passive film is composed of an inner barrier layer and an outer porous layer. Exposure for 72 h in the MEM solution results in the formation of a surface layer composed of an island-like distribution of HA material and adsorbed amino acids. The addition of H2O2 to the MEM solution strongly promotes the formation of a thicker, continuous nanocomposite layer of HA and amino acids. For Ti alloys, the release of H2O2 in the anti-inflammatory response appears to be an important beneficial process, as it serves to accelerate osseointegration. Copyright c � 2008 John Wiley & Sons, Ltd.

Characterization of skin Port-Wine Stain and Hemangioma vascular lesions using Doppler OCT.

Abstract: Background Port-Wine Stains (PWS) are vascular malformations of the dermis, whereas hemangiomas are vascular tumors usually present at birth. Early non-invasive diagnosis of the vascular lesion would greatly increase treatment efficiency. We propose to use optical coherence tomography (OCT), a morphological imaging technique, coupled with functional blood-flow Doppler modality. Methods We imaged lesions from five patients: one with PWS, four with hemangiomas, using a Thorlabs Swept-Source OCT system at 1325 nm. Additional Doppler images allow for distinguishing blood vessels from empty cavities that appear similar on conventional OCT images. Results We are able to distinguish between normal skin and vascular lesions. The PWS lesion presents blood vessels of mean diameter 114 μm with a standard deviation of 92 μm, and mean depth 304 μm with a standard deviation of 99 μm. The hemangiomas present blood vessels of mean diameter 39 μm with a standard deviation of 19 μm, and mean depth 298 μm with a standard deviation of 133 μm. Conclusion We show a significant difference between the vascular characteristics of the studied PWS and hemangiomas lesions. We believe that OCT complemented by Doppler OCT could be a promising method for future non-invasive diagnosis and monitoring of some vascular lesions.

Degradation of chlorpyrifos by ionizing radiation

Abstract: Chlorpyrifos is an organophosphate pesticide commercialized since 1965 and it is now one of the top five commercial insecticides. It is registered for use in over 900 different pesticide formulations in the world. Chlorpyrifos poisoning usually affects many organs of the body, such as the central and peripheral nervous system, eyes, respiratory system, and the digestive tract. Depending on the pesticide formulation and type of application, chlorpyrifos residues may be detectable in water, soil, and on the surfaces from months to years. This paper presents preliminary studies of the removal of chlorpyrifos by exposition to ionizing radiation, to be applied in pesticide container decontamination. Samples containing various concentrations of chlorpyrifos in acetonitrile were irradiated with absorbed doses varying from 5 to 50 kGy, using a 60Co gamma-source with 5,000 Ci activity (Gamma cell type). The chemical analysis of the chlorpyrifos and the by-products resulted from the radiolitic degradation were made using a gas chromatography associated to mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GC-FID).