Abstract: At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of gold nanoparticles, the radiolytic synthesis allows proper control of the nucleation process without the need for reducing agents, in a single step, combined or not with simultaneous sterilization. This review details and summarizes the use of radiation technologies for the synthesis and preparation of gold nanoparticles concerning fundamental aspects, mechanism, current pathways for synthesis and radiation sources, as well as briefly outlines final applications and some toxicity aspects related to nanogold-based systems.

Palavras-Chave: gold; nanoparticles; gamma radiation; electron beams; x-ray sources; radiolysis; nanotechnology; medicine; diagnostic uses; ionizing radiations

FREITAS, LUCAS F. de; VARCA, GUSTAVO H.C.; BATISTA, JORGE G. dos S.; LUGAO, ADEMAR B. An overview of the synthesis of gold nanoparticles using radiation technologies. Nanomaterials, v. 8, n. 11, 2018. DOI: 10.3390/nano8110939. Disponível em: http://repositorio.ipen.br/handle/123456789/29423. Acesso em: $DATA.

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Abstract: The aim of this paper is to characterize 3D printed phantoms and printing set-ups with different infill percentages for imaging energy X-ray beams attenuation. 3D printing performance was studied using the fused filament fabrication (FFF) technique with PLA (Polylactic Acid) and ABS (Acrylonitrile Butadiene Styrene) filaments. Phantom plates were printed and, using the Pantak Seifert X-ray system with different beam qualities in the diagnostic range, the attenuation coefficients were obtained experimentally with the transmission method and results compared with PMMA used as reference and theoretical data. Different percentages of infill of printed phantoms were also evaluated and transmission characterized. The attenuation coefficients were determined for the different beam qualities and results show that the variation in the values of attenuation coefficients decreases as the infill quality increases. Attenuation characteristics evaluated indicates the suitable equivalence of PLA to PMMA for 3D printing water/tissue equivalent most complex geometry phantoms. The different printing modes characterized together with their attenuation coefficients for the X-ray beams will be studied and used in the development of new 3D printed phantoms in our institute.

Palavras-Chave: phantoms; computer codes; x-ray sources; lactic acid; dosimetry; acrylonitrile; butadiene; styrene; radiations; beams

VILLANI, D.; RODRIGUES JUNIOR, O.; CAMPOS, L.L. Dosimetric characterization of 3D printed phantoms at different infill percentages for diagnostic X-ray energy range. Radiation Physics and Chemistry, v. 172, p. 1-6, 2020. DOI: 10.1016/j.radphyschem.2020.108728. Disponível em: http://repositorio.ipen.br/handle/123456789/31432. Acesso em: $DATA.

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Abstract: Model-based dose calculation algorithms (MBDCAs) are the current tools to estimate dose in brachytherapy, which takes into account heterogeneous medium, therefore, departing from water-based formalism (TG-43). One aspect associated to MBCDA is the choice of dose specification medium since it offers two possibilities to report dose: (a) dose to medium in medium, D-m,D-m; and (b) dose to water in medium, D-w,D-m. The discussion about the preferable quantity to be reported is underway. The dose conversion factors, DCF, between dose to water in medium, D-w,D-m, and dose to medium in medium, D-m,D-m, is based on cavity theory and can be obtained using different approaches. When experimental dose verification is desired using, for example, thermoluminescent LiF dosimeters, as in in vivo dose measurements, a third quantity is obtained, which is the dose to LiF in medium, D-LiF,D-m. In this case, DCF to convert from D-LiF,D-m to Dw, m or Dm, m is necessary. The objective of this study is to estimate DCFs using different approaches, present in the literature, quantifying the differences between them. Also, dose in water and LiF cavities in different tissue media and respective conversion factors to be able to convert LiF-based dose measured values into dose in water or tissue were obtained. Simple cylindrical phantoms composed by different tissue equivalent materials (bone, lung, water and adipose) are modelled. The phantoms contain a radiation source and a cavity with 0.002 69 cm(3) in size, which is a typical volume of a disc type LiF dosimeter. Three x-rays qualities with average energies ranging from 47 to 250 keV, and three brachytherapy sources, Co-60, Ir-192 and Cs-137, are considered. Different cavity theory approaches for DCF calculations and different cavity/medium combinations have been considered in this study. DCF values for water/bone and LiF/bone cases have strong dependence with energy increasing as the photon energy increases. DCF values also increase with energy for LiF/lung and water/lung cases but, they are much less dependent of energy. For LiF/adipose, water/adipose and LiF/water cases, the DCF values are also dependent of photon energy but, decreases as the energy increases. Maximum difference of 12% has been found compared to values in literature.

Palavras-Chave: monte carlo method; water; lithium fluorides; x-ray sources; brachytherapy; doses; comparative evaluations; skeleton; lungs; adipose tissue; phantoms; cobalt 60; iridium 192; cesium 137

BRANCO, ISABELA S.L.; ANTUNES, PAULA C.G.; FONSECA, GABRIEL P.; YORIYAZ, HELIO. Monte Carlo studies on water and LiF cavity properties for dose-reporting quantities when using x-ray and brachytherapy sources. Physics in Medicine & Biology, v. 61, p. 8890-8907, 2016. DOI: 10.1088/1361-6560/61/24/8890. Disponível em: http://repositorio.ipen.br/handle/123456789/26989. Acesso em: $DATA.

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Abstract: In this study, hybrid poly(dimethylsiloxane)-derived hydroxyurethanes films (PDMSUr-PWA) containing phosphotungstic acid (H3PW12O40/PWA) were characterized using field emission gun scanning electron microscopy (FEG-SEM), in attenuated total reflectance Fourier transform mid-infrared mode (ATR FT-MIR), and analyzed using synchrotron radiation micro-X-ray fluorescence (SR-mXRF), synchrotron radiation grazing incidence X-ray fluorescence (SR-GIXRF), laserinduced breakdown spectroscopy (LIBS), and instrumental neutron activation analysis (NAA) in order to correlate the distribution patterns of tungsten and properties of PDMSUr-PWA films. PDMS constitute elastomers with good mechanical, thermal, and chemical (hydrophobicity/non-hygroscopy) resistance. Currently, products based on urethanes (e.g., polyurethanes) are widely used in many applications as plastics, fiber-reinforced polymers, high-performance adhesives, corrosion-resistant coatings, photochromic films, among others. The possibility to combine inorganic and organic components can produce a hybrid material with unique properties. PWA has an important role as agent against the corrosion of steel surfaces in different media, besides exhibiting amazing catalytic and photochromic properties in these films. PWA kept its structure inside of these hybrid films through interactions between the organic matrix of PDMSUr and silanol from the inorganic part (organically modified silica), as was shown using ATR FT-MIR spectra. The FEG-SEM/SR-mXRF/wideangle X-ray scattering (WAXS)/X-ray diffraction (XRD)/energy dispersive X-ray results proved the presence of PWA in the composition of domains of PDMSUr-PWA films. At PWA concentrations higher than 50 wt%/wt, tungsten segregation across the thickness is predominant, while that at PWA concentrations lower than 35 wt%/wt, tungsten segregation at surface is predominant. Inhomogeneities in the tungsten distribution patterns (at micrometric and millimetric level) may play an important role in the mechanical properties of these films (elastic modulus and hardness).

Palavras-Chave: hydroxy compounds; hybridization; films; synchrotron radiation; neutron activation analysis; spectroscopy; breakdown; laser spectroscopy; x-ray fluorescence analysis; x-ray sources

YSNAGA, ORLANDO E.; AGUIAR, KELEN M.F.R. de; ZAMBONI, CIBELE B.; POLITO, WAGNER L.; RODRIGUES-FILHO, UBIRAJARA P. Qualitative and semiquantitative determination of the atomic and molecular tungsten distributions in hybrid hydroxyurethanes–poly(dimethylsiloxane) films containing phosphotungstates ([PW12O40]3–). Applied Spectroscopy, v. 74, n. 12, p. 1515-1529, 2020. DOI: 10.1177/0003702820945018. Disponível em: http://200.136.52.105/handle/123456789/31591. Acesso em: $DATA.

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Abstract: Turning chips of zirconium alloys are produced in large quantities during the machining of alloy rods for the fabrication of the end plugs for the Pressurized Water Reactor (PWR) fuel elements parts of Angra II nuclear reactor (Brazil – Rio de Janeiro). This paper presents a study on the search for an efficient way for the cleaning, quality control and Vacuum Arc Remelting (VAR) of pressed zirconium alloys chips to produce a material viable to be used in the production of the fuel rod end plugs. The process starts with cutting oil clean out. The first step in this process consists in soaking a bunch of chips in clean water, to remove soluble cutting oils, followed by an alkaline degreasing bath and a wash with a high-pressure flow of water. Drying is performed by a flux of warm air. The oil free chips are then subjected to a magnet in order to detect and collect any magnetic material, essentially ferrous, that may be present in the original chips. Samples of the material are collected and then melted in a small non consumable electrode vacuum arc furnace for evaluation by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRFS) in order to define the quality of the chips. The next step consists in the 15 ton hydraulic pressing the chips in a die with 40 mm square section and 500 mm long, producing an electrode with 20% of the Zircaloy bulk density. The electrode was finally melted in a laboratory scale modified VAR furnace located at the CCTM–IPEN, producing 0.8 kg ingots. The authors conclude that the samples obtained from the fuel element industry can be melting in a VAR furnace, modified to accommodate low density electrodes, allowing a reduction up to 40 times the original storage volume, however, it is necessary to remelt the ingots to correct their composition in order to recycle the original zirconium alloys chips. in a process to reduce volume and allow the reutilization of valuable Zircaloy scraps.

Palavras-Chave: zirconium alloys; recycling; melting; pwr type reactors; vacuum melting; fuel elements; fluorescence spectroscopy; x-ray sources; angra-2 reactor; electric arcs

MUCSI, C.S.; REIS, L.A.M. dos; GOMES, M.P.; PEREIRA, L.A.T.; ROSSI, J.L. Study on the viability of the recycling by electric arc melting of zirconium alloys scraps aiming the scalability of the process. Materials Science Forum, v. 930, p. 495-500, 2018. DOI: 10.4028/www.scientific.net/MSF.930.495. Disponível em: http://repositorio.ipen.br/handle/123456789/29326. Acesso em: $DATA.

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