Abstract: At the transition from quiescence to propagating waves recorded in isolated retinas, a circular electric current closes in the extracellular matrix; this circular current creates a magnetic torus flow that, when entering quiescent tissue in front of the wave, recruits elements and when leaving behind, helps to build the absolute refractory state. The waving magnetic torus is the consequence of the vortex effect and explains the energy boost that drives propagation. Methods: We interpret experimental results from intrinsic and extrinsic fluorescence dyes, voltage, calcium and pH sensitive, optical signals from isolated retinas, and time series recordings using ion exchange resins: Ca, K, pH, Na, Cl recorded extracellularly at retinas, cerebellums and cortices coupled to spreading depression waves. Finally, we checked the ECoG activity, also a time series, at the transition from after discharges to spreading depression in rat hippocampus. Results: The integrated assessment of the diversified measurements led to the realization that the magnetic flow at the wavefront is a major contributor to the wave propagation mechanisms. This flow couples mass and charge flows as a swirling torus from excited to quiescent tissue. Conclusions: An alternative model of the brain is possible, apart from the classical HH and molecular biology model. Physical chemistry of charged gels and its flows explains the results. The conceptual framework uses far from equilibrium thermodynamics.

Palavras-Chave: brain; electrochemistry; retina; resonance; central nervous system; vortices; vortex flow

LIMA, VERA M.F. de; PEREIRA JUNIOR, ALFREDO; OLIVEIRA, GUILHERME L. de. The spreading depression propagation: how electrochemical patterns distort or create perception. Open Journal of Biophysics, v. 11, n. 2, p. 133-146, 2021. DOI: 10.4236/ojbiphy.2021.112003. Disponível em: http://repositorio.ipen.br/handle/123456789/31942. Acesso em: $DATA.

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Abstract: The response of thin diodes (SFH206k) as dosimeters has been investigated employing the beam of an electron accelerator within the dose rate range of 2–8 kGy/s and accumulated doses up to 100 kGy. These devices, operating in the short-circuit mode and under industrial irradiation conditions, deliver current signals nonlinearly dependent on the dose rate, whichever the dose history of the diodes, due to the high density of the generated electron-hole pairs herein achieved. Despite this nonlinearity, the dose rate response is stable and characterized by current signals with repeatability better than 2.0%, regardless of the accumulated dose. It is also found that the dose responses are quite linear with sensitivities slightly dependent on the accumulated dose at a constant dose rate. The decrease in the charge sensitivity, taking as reference that obtained before any radiation damage, reaches only 9% (k = 2) at 100 kGy, which is much smaller than the values reported in the literature. From this low aging and the repeatability of both dose rate and dose responses, it seems that the photodiode under investigation is a low budget alternative, good enough for routine dosimetry, provided it has been previously calibrated in the same processing facility.

Palavras-Chave: photodiodes; dosimetry; electron beams; dosemeters; electron dosimetry; si semiconductor detectors; dose rates

GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; ASFORA, VIVIANE K.; KHOURY, HELEN J.; BUENO, CARMEN C. The response of low-cost photodiodes for dosimetry in electron beam processing. Radiation Physics and Chemistry, v. 181, p. 1-8, 2021. DOI: 10.1016/j.radphyschem.2020.109335. Disponível em: http://repositorio.ipen.br/handle/123456789/31961. Acesso em: $DATA.

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Abstract: Industrial-scale extruded profiles of AA 7108 with a rectangular section (25.60 mm x 15.95 mm) were used in this investigation. Some complementary microstructural analysis techniques, such as polarized light microscopy, EBSD (Electron Backscatter Diffraction) and X-ray diffraction were used to characterize the microstructure, focusing on the PCG zone. It was observed that the extruded profiles presented a totally recrystallized microstructure and a 300 μm layer of peripheral coarse grains. Additionally, the results showed that the PCGZ predominant grain orientation {311} <110> differs from the texture below the PCGZ (Goss and Cube components).

Palavras-Chave: aluminium alloys; crystallography; microstructure; metallography; extrusion

SOUZA, SAUL H. de; PLAUT, RONALD L.; LIMA, NELSON B. de; OLIVEIRA, RENE R. de; PADILHA, ANGELO F. The occurrence of a peripheral coarse grain zone (PCGZ) in extruded bars of AA 7108. Materials Science Forum, v. 1016, p. 1141-1146, 2021. DOI: 10.4028/www.scientific.net/MSF.1016.1141. Disponível em: http://repositorio.ipen.br/handle/123456789/32044. Acesso em: $DATA.

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Abstract: The goal of NUMEN project is to access experimentally driven information on Nuclear Matrix Elements (NME) involved in the neutrinoless double beta decay (0νββ) by accurate measurements of the cross sections of heavy-ion induced double charge-exchange reactions. In particular, the (18O, 18Ne) and (20Ne, 20O) reactions are adopted as tools for β+β+ and β−β− decays, respectively. The experiments are performed at INFN–Laboratory Nazionali del Sud (LNS) in Catania using the Superconducting Cyclotron to accelerate the beams and the MAGNEX magnetic spectrometer to detect the reaction products. The measured cross sections are very low, limiting the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. In order to make feasible a systematic study of all the candidate nuclei, a major upgrade of the LNS facility is foreseen to increase the experimental yield by more than two orders of magnitude. To this purpose, frontier technologies are being developed for both the accelerator and the detection systems. An update description of the NUMEN project is presented here, focusing on recent achievements from the R&D activity.

Palavras-Chave: matrix elements; nuclear matrix; double beta decay; charge exchange; heavy ions; ion detection; magnetic spectrometers; gamma spectrometers

CAPPUZZELLO, FRANCESCO; ACOSTA, LUIS; AGODI, CLEMENTINA; BOZTOSUN, ISMAIL; BRISCHETTO, GIUSEPPE A.; CALABRESE, SALVATORE; CALABRETTA, LUCIANO; CALVO, DANIELA; CAMPAJOLA, LUIGI; CAPIROSSI, VITTORIA; CARBONE, DIANA; CAVALLARO, MANUELA; CHAVEZ, EFRAIN; CIRALDO, IRENE; DELAUNAY, FRANCK; DJAPO, HARIS; FERRARESI, CARLO; FINOCCHIARO, PAOLO; FISICHELLA, MARIA; GANDOLFO, ELISA M.; IAZZI, FELICE; MORALLES, MAURICIO; NERI, LORENZO; OLIVEIRA, JOSE R.B.; PANDOLA, LUCIANO; PETRASCU, HORIA; PINNA, FEDERICO; RUSSO, ANTONIO D.; SARTIRANA, DIEGO; SGOUROS, ONOUFRIOS; SOLAKCI, S.O.; SOUKERAS, VASILEIOS; SPATAFORA, ALESSANDRO; TORRESI, DOMENICO; TUDISCO, SALVATORE; YILDIRIM, AYDIN. The NUMEN project: an update of the facility toward the future experimental campaigns. Frontiers in Astronomy and Space Sciences, v. 8, p. 1-15, 2021. DOI: 10.3389/fspas.2021.668587. Disponível em: http://repositorio.ipen.br/handle/123456789/32016. Acesso em: $DATA.

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Abstract: Rhamnolipids (RLs) comprise a class of glycolipids produced by Pseudomonas aeruginosa under appropriate culture medium. They act as biosurfactants being composed by a hydrophilic head of either one (mono-RL) or two (di-RL) rhamnose moieties coupled to hydroxyaliphatic chains. It is well accepted that RLs present low biolitic activity as compared to other synthetic surfactants. However, their mechanisms of action in biological systems are not well defined yet. The interaction of RLs with lipid bilayers are here investigated to address how they impact on plasma membrane at molecular level. Our experimental approach was based on a deep analysis of optical microscopy data from giant unilamellar vesicles (GUVs) dispersed in aqueous solutions containing up to 0.5 mM of commercially available RLs (a mixture of mono-RL, 33–37 mol%, and di-RL, 63–67 mol%, cmc of 0:068 ± 0:005 mM). GUVs were made up of a single lipid POPC and a ternary system containing DOPC, sphingomyelin and cholesterol, which mimic lipid raft platforms. Our results demonstrate that RLs have a low partition in the lipid bilayer in respect to the total molecules in solution. We suppose that RLs insert in the outer leaflet with low propensity to flip-flop. In the case of POPC GUVs, the insertion of RL molecules in the outer leaflet impairs changes in spontaneous membrane curvature with incubation time. Then, small buds are formed that remain linked to the original membrane. No changes in membrane permeability have been detected. A remarkable result refers to the insertion of RLs in membranes containing liquid ordered (Lo) - liquid disordered (Ld) phase coexistence. The rate of interaction has been observed to be higher for Ld phase than for Lo phase (0:12 . 10-6 s-1 and 0:023 . 10-6 s-1 for Ld and Lo, respectively, at RL concentration of 0.5 mM). As a consequence, the preferential RL insertion in Ld phase may also alter the membrane spontaneous curvature which, coupled to the change in the line tension associated to the domains boundary, conducted to Lo domain protrusion. Even if it has been observed on a model system, such membrane remodelling might correlate to endocytic processes activated in cell membranes, regardless of the participation of specific proteins. Further, changes imposed by RLs in lipid rafts may affect the association of key proteins enrolled in cell signaling, which may perturb cell homeostasis.

Palavras-Chave: membranes; lipids; cell membranes; microorganisms; plasma; pseudomonas; surfactants

COME, BENEDETTA; DONATO, MARESSA; POTENZA, LUCIA F.; MARIANI, PAOLO; ITRI, ROSANGELA; SPINOZZI, FRANCESCO. The intriguing role of rhamnolipids on plasma membrane remodelling: from lipid rafts to membrane budding. Journal of Colloid and Interface Science, v. 582, n. Part B, p. 669-677, 2021. DOI: 10.1016/j.jcis.2020.08.027. Disponível em: http://200.136.52.105/handle/123456789/31623. Acesso em: $DATA.

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Abstract: The scattered radiation from interventional procedures is an important source of radiological risk for the medical staff. Considering all affected organs, the eye lens is among the most critical organs. As pointed out by several studies, even for low radiation doses, the appearance of cataract may occur. Considering this scenario, the radiation doses to the eye lens were determined using three different lead eyewear models commonly employed in the interventional radiology. The interventional radiologist was represented by an adult virtual anthropomorphic phantom (MASH3), coupled to the Monte Carlo code MCNP 6.1, in a typical cardiac interventional radiology procedure. The eyewear had a thickness 0.5 mmPb each, and the evaluation was carried out for four different beam angulations (PA, LAO90, LAO65 e RAO65), utilizing a tube voltage of 80 kVp, and HVL of 4 mmAl. The results pointed out that the shielding efficiency has a strong dependence on the eyewear type utilized, which may be very useful for the decision-making during the acquisition of such equipments.

Palavras-Chave: crystalline lens; equivalent radiation doses; fluoroscopy; glass; lead; monte carlo method; occupational exposure; phantoms; radiation protection; shielding

SANTOS, W.S.; NEVES, L.P.; PERINI, A.P.; SANTOS, C.J.; BELINATO, W.; CALDAS, L.V.E. The influence of the lead eyewear geometry on the doses to the eye lens. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-9, 2021. DOI: 10.15392/bjrs.v9i1A.1347. Disponível em: http://repositorio.ipen.br/handle/123456789/32098. Acesso em: $DATA.

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Abstract: Gaining prominence in clinical practice, the 68Ga, positron emitter radionuclide easily obtained by 68Ge/68Ga generator elution, has shown potential and excellent quality on radiolabeling of peptide for use in positron emission tomography (PET), in particular urea-based inhibitor peptides, directed to the prostate-specific membrane receptor (PSMA). Previous studies with the PSMA linked to the chelator HBED-CC (PSMA-11) radiolabeled with 68Ga showed high contrast PET/CT images to evaluate recurrence and metastasis of prostate cancer, becoming an important imaging agent in the clinical routine. This work intended to evaluate the influence of the quality of the 68Ge/68Ga generator eluate in direct labelling of PSMA-11 with 68Ga, assisting in the development of kit for prompt radiolabeling. It was evaluated the 68GaCl3 eluate from 68Ge/68Ga non-GMP generator (manufacturer A) and 68Ge/68Ga GMP generator (manufacturer B), both commercially available. To evaluate the influence of the 68Ga eluate on radiochemical yield of the preparations, the radiochemical purity was determined by thin layer chromatography and HPLC. The radiolabeling with non-GMP generator eluate was made with and without preliminary purification of the 68 gallium chloride eluate, employing cationic purification columns. The results showed higher radiochemical yield with the 68GaCl3 eluate from the 68Ge/68Ga GMP generator, obtaining the radiolabeled product more easily and speed to clinical practice, without preliminary purification, as opposed to the use of non-GMP 68Ge/68Ga generator which required preliminary purification of the 68GaCl3 eluate to promote satisfactory radiochemical purity results.

Palavras-Chave: carcinomas; prostate; neoplasms; positron computed tomography; membrane proteins; gallium 68; germanium 68

VIVALDINI, B.F.; ARAUJO, E.B. The influence of generator eluate in radiolabeling PSMA-11 kit with 68Ga. Brazilian Journal of Radiation Sciences, v. 9, n. 1A, p. 1-9, 2021. DOI: 10.15392/bjrs.v9i1A.1541. Disponível em: http://repositorio.ipen.br/handle/123456789/32139. Acesso em: $DATA.

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Abstract: BACKGROUND Bacaba (Oenocarpus bacaba Mart.) has a high yield of oil, with the potential to produce biologically active natural products and can be considered a new "superfruit" with high value added. METHODS Acid value, peroxide value, refractive index, saponification value, p-anisidine value, relative density, iodine value, total oxidation value, specific extinction coefficients at 232 and 270 nm (K232 and K270), ΔK, and color were determined. RESULTS The most significant changes in the quality values, such as peroxide (26.25 mEq·kg-1), p-anisidine (11.41), acidity (14.66 mg KOH·g-1 oil), and total oxidation (63.92) were determined for 15 min of microwave heating. CONCLUSIONS The microwave heating promoted the acceleration of oxidative processes showing that, overall, much care should be taken when heating the bacaba oil by microwave to avoid oil degradation.

Palavras-Chave: fruits; vegetable oils; microwave radiation; radiation effects; heating; tropical regions

FONSECA, HUGO M.; SANTOS, CAMILA O.; CRUZ, LUIS P.A.; ARTHUR, VALTER; FREITAS, BARBARA C.B.; SOUZA, ADRIANA R.M.; MARTINS, GLENDARA A.de S. The effects of microwave application on the physicochemical properties of bacaba (Oenocarpus bacaba Mart.) oil. Acta Scientiarum Polonorum Technologia Alimentaria, v. 20, n. 2, p. 189-196, 2021. DOI: 10.17306/J.AFS.2021.0893. Disponível em: http://repositorio.ipen.br/handle/123456789/32603. Acesso em: $DATA.

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Abstract: In this work Fe3O4:Er nanoparticles (NPs) with the characteristic size of ~ 11 nm were synthesized via classic co-precipitation method. Electron microscopy and X-ray diffraction were employed to probe the morphology and structure of the samples. Results revealed that samples synthesized in the Fd-3mZ structure with lattice constant close to that of pure magnetite. 111In probe generator was incorporated at synthesis in order to map the evolution of hyperfine magnetic field with temperature using time differential perturbed angular correlation (TDPAC) spectroscopy. The TDPAC results are discussed in terms of the effect of Er dopant on the magnetic properties and local structure of the NPs.

Palavras-Chave: differential pac; coprecipitation; nanoparticles; magnetic properties; doped materials

RODRIGUES, PRISCILA S.; BURIMOVA, ANASTASIA; SALES, TATIANE S.N.; FILHO, ARNALDO A.M.; OTUBO, LARISSA; SAXENA, RAJENDRA N.; CARBONARI, ARTUR W. The effect of Er doping on local structure of magnetite nanoparticles. Hyperfine Interactions, v. 242, n. 38, p. 1-6, 2021. DOI: 10.1007/s10751-021-01767-x. Disponível em: http://repositorio.ipen.br/handle/123456789/32601. Acesso em: $DATA.

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Abstract: This work presents the feasibility studies to convert the UO2 core of the Westinghouse AP1000 reactor to a U/Th core aiming at U/Th fuel recycling. The focus of the work is to establish a first core which allows normal operation of the AP1000 reactor and investigate a possible route for generating the 233U for U/Th fuel recycling. The converted core named AP-Th1000 is divided in three homogenous zones with different UO2/ThO2 mass proportions. The reprocessing procedure envisioned is to separate fission products and Pu isotopes, retain Uranium, use this fuel material in subsequent fuel cycles and complement the required fissile material with U with enrichment below 20%. The goal was to gradually reduce the mass proportion of mined Uranium fuel and eventually attain a Th-233U core with similar operation characteristics of current AP1000 core. We perform a detailed three-dimensional full core analysis with the SERPENT code examining core reactivity, power density distribution, and also a preliminary closed cycle study for the first 4 cycles where the production of 233U are evaluated. The goal of converting the AP1000 reactor core to a U/ThO2 fuel cycle was partially accomplished. While the first cycle was thoroughly examined and met all requirements we were not able to find a route to migrate it to a prevalent Th cycle. Basically, two of the set of criteria adopted in the study proved to be too restrictive to attain this goal with homogenous assembly, namely U enrichment below 20% and not recycling Pu. The results indicate that removing these two criteria the conversion factor in the ensuing fuel cycles can be increased and possibly attain a Th cycle without compromising the economics of power generation. The design changes were the elimination of IFBA burnable absorbers and replacement of gray control bundles by black control bundles.

Palavras-Chave: thorium; pwr type reactors; reactor cores; fuel cycle

STEFANI, GIOVANNI L. de; MAIORINO, JOSE R.; MOREIRA, JOAO M. de L. The AP-Th 1000: an advanced concept to use MOX of thorium in a closed fuel cycle. International Journal of Energy Research, v. 45, n. 8, p. 11642-11655, 2021. SI, DOI: 10.1002/er.5421. Disponível em: http://repositorio.ipen.br/handle/123456789/32064. Acesso em: $DATA.

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