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Thermoluminescence and Optically Stimulated Luminescence of CaSO4:Mn,Tb with different dopant concentrations
2024 - SILVA, A.M.B.; SOUZA, D.N.; CALDAS, L.V.E.
This study systematically evaluates the thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of CaSO4 crystals doped with manganese (Mn) and terbium (Tb), focusing on dopant concentrations within the ranges of Mn (0.1 mol% – 2 mol%) and Tb (0.05 mol% – 1 mol%). Synthesized via the slow evaporation route, this investigation is part of an ongoing experimental series initiated by Silva et al. (2022) [1], exploring CaSO4:Mn,Tb crystals at a concentration of 0.1 mol%, the validating their properties for dosimetric purposes. A structural phase identification was conducted using X-ray diffraction, and emission and excitation photoluminescence (PL) spectra confirmed the presence of Tb3+ and Mn2+ ions in the crystalline matrices. Dosimetric characterization utilized pellets prepared by incorporating Teflon into the phosphors. In-depth investigations involved analyzing TL glow curves and Continuous Wave Optically Stimulated Luminescence (CW-OSL) curves. Observations revealed that TL intensity increased as the co-doped concentration of Tb decreased while maintaining the concentration of Mn constant. Conversely, at a constant terbium concentration, TL intensity was higher with 0.5 mol% of manganese compared to 0.1 mol%, but higher concentrations of manganese (1 mol% and 2 mol%) resulted in decreased TL intensity. The study also explored dose-response, reproducibility, fading, sensitivity, step-annealing curve analyses, experimental determination of temperature dependence, and the minimum detectable dose (MDD) exposed to beta radiation of the pellets. This research underscores the importance of optimizing dopant concentrations to enhance the potential of these phosphors for precise and reliable dosimetry, thereby advancing both the understanding of these materials and their potential for further development in the field of radiation dosimetry.
Performance evaluation of a new dosimetric system for lens dosimetry made using 3D printing
2024 - NASCIMENTO, G.G.; RODRIGUES JUNIOR, O.; SAVI, M.; VILLANI, D.; POTIENS, M.P.A.
Technology advances in the health sector make it possible for medical radiology services, especially interventional radiology, to be more requested by doctors, which results in a significant increase in the number of procedures performed and the number of patients and occupationally exposed individuals (OEI) [1]. This increase in exposure of OEIs has caused concern regarding the exposure of the lens to ionizing radiation, since this tissue is considered a tissue with high radiosensitivity. This concern about exposing the lens region to ionizing radiation has existed for more than 10 years [2], considering these concerns, in 1950 the International Commission on Radiological Protection (ICRP) listed the lens of the eye as a critical organ [3]. In 2011, ICRP recommended a reduction in the occupational dose limit for the lens region from 150 mSv/year to 20 mSv/year [4]. In addition to technology advances and optimization of procedures used to reduce doses and risks that may affect the patient in interventional radiology applications, it is necessary to have a monitoring system suitable for the occupation. This monitoring is carried out using a dosimeter, which is part of a dosimetric system composed of a dosimeter holder, detector and a reading system compatible with the detector. In this work, chip-shaped LiF:Mg,Ti thermoluminescent detectors, commercially known as TLD-100, were used. For this study, a dosimeter holder produced in 3D printing was developed for use in eye lens dosimetry. A Raise 3D printer model Pro2 was used, which works using the FFF technique, the dosimeter holders were made from PLA and ABS material. The dosimeter holder has space to accommodate up to two chip-shaped detectors and has a support that fits with the glasses stem. The irradiations were carried out using Pantak/Seifert X-ray equipment, model Isovolt 60 HS. The N-100 radioprotection quality was used, with an energy of 83 keV, within the energy range between 40 and 120 keV, the quality used is within the range used in interventional radiology. The tests were conducted in accordance with the recommendations of ISO 12794:2000 [5]. From a dosimetric point of view, the type of material used to manufacture the dosimeter holders did not present significant differences. However, dosimeter holders made of PLA showed better resistance during the procedures.
Operational and Dosimetric Parameters of a 1.5 MeV electron beam irradiator in static and dynamic irradiation modes
2024 - GONÇALVES, J.A.C.; ASFORA, V.K.; KHOURY, H.J.; BUENO, C.C.
Electron beam (EB) accelerators have been increasingly used in radiation processing applications. Most aim to achieve reproducible chemical and biological effects on the irradiated material to preserve or modify its characteristics with tight control of the absorbed dose (10-100 kGy). Accurate dosimetry, mainly carried out with standard reference alanine dosimeters and cellulose triacetate (CTA) films, is essential to ensure the reliability of the whole process [1]. However, variations in the electron energy, beam profiles, attainable dose rate, and conveyor speed also affect the dose absorbed in the irradiated product, requiring constant control and monitoring of these parameters. This task is accomplished with passive dosimeters in static irradiation mode following the international standard recommendations. To broaden the quality control of the irradiation process, it has been proposed to investigate the feasibility of using a homemade diode-based dosimetry system to measure the electron beam profiles and monitor variations in the radiation field in an industrial EB accelerator (DC 1500/25/04JOB188) [2]. This innovative system, when implemented, can provide real-time data, enabling immediate action and avoiding unexpected shutdowns, thereby enhancing the efficiency of the process. The dosimetry probe comprises a commercial diode (230 µm thick; 7.0 mm2 area), with the p+ front pad connected to the Keithley 6517B electrometer in the short-circuit mode. In dynamic mode, irradiations are carried out by sending the probe through the radiation field in the conveyor direction, varying speeds from 2 to 10 m/min. For reference, static measurements are also gathered with alanine pellets and cellulose triacetate (CTA) films. Regardless of the irradiation modes and the dosimeter types, the beam profiles and dose measurements are in good agreement, as shown in Fig.1. The data reproducibility remains to be investigated.
Implementation of a procedure for calibrating parallel plate ionization chambers in energy X-ray beams
2024 - DIAS, F.S.; JUNIOR RODRIGUES, O.; POTIENS, M.P.A
Radiotherapy can be a low-cost method of treating cancer if appropriate diagnostic and therapeutic equipment, associated with well-trained staff, is available. Among the various modalities available for treatment, intraoperative radiotherapy (IORT) is a good option as it is a method based on a high dose of radiation administered to the tumor bed immediately after surgical excision, thus reducing treatment time.[1,2] IORT can be obtained using miniature accelerators capable of producing low-energy X-rays with voltages ranging from 30 to 50 kilovolts, for example, in the ZEISS INTRABEAM system (Carl Zeiss Meditec AG, Jena, Germany) present in hospitals such as Oswaldo Cruz and AC.Camargo in São Paulo, Brazil. [3] One of the difficulties related to this system is carrying out adequate dosimetry and calibration of the system. According to the recently updated TRS 398 recommendations, for the use of low energy beams, the ideal is to use a parallel plate ionization chamber calibrated in terms of absorbed dose in water. [4] Thus, this work aimed to establish a calibration procedure for parallel plate ionization chambers in terms of absorbed dose in water at the Ionizing Radiation Metrology Center (CEMRI) at the Institute for Energy and Nuclear Research (IPEN). To confirm the procedure, the calibration of 4 parallel plate ionization chambers was carried out, including one belonging to a private hospital.
Energy dependence of an epitaxial diode in standard diagnostic radiology beams
2024 - GONÇALVES, J.A.C.; MANGIAROTTI, A.; ANTONIO, P.L.; CALDAS, L.V.E.; BUENO, C.C.
The overall response of a radiation-hard epitaxial diode has been previously investigated for radiation diagnostic radiology qualities (RQR-3, RQR-5, RQR-8, and RQR-10) and computed tomography qualities (RQT-8, RQT-9, and RQT-10) beams. The EPI diode has a thin n-type epitaxial layer (25-75 µm) grown on a thick (300-500 µm) Czochralski silicon substrate and a p-n junction provided by a highly doped ptype silicon layer ( 1 µm). When operating as a dosimeter in the short-circuit current mode, the dosimetric parameters of the diode regarding repeatability (< 0.3%), long-term stability (0.4%/year), angular response (< 3%, ± 5º), dose rate dependence (< 3%), and signal-to-noise ratio (≥ 1500) fully adhered to the IEC 61674 recommendations [1]. However, compliance with the energy dependence requirement (≤ 5%) was not achieved for RQR-10 and RQT-10 beams, with average energies of 60 keV upward. This unexpected dependence, experimentally manifested by variations in the charge sensitivities, might be associated with the physical phenomena underlying the photon interaction with the complex design of the EPI diode. This work aims to provide a theoretical basis for the data previously gathered with the EPI diode and validate its use as a dosimeter for low-energy photon beams. It has been accomplished through current and charge sensitivities calculations considering the diode as a thin abrupt junction supported on a highly doped Czochralski substrate, the minority carriers' diffusion lengths, and the X-ray energy spectra from a PantakSeifert 160HS Isovolt X-ray generator. The theoretical results are compared to the experimental ones, as visible in Fig.1. Despite the overall data agreement in the low-energy region, the discrepancy between the experimental and calculated values for photons of 60 keV upward remains to be investigated. Studies in this direction are underway.
Effect of the UV lighting for photo-transfer of the charges of radiation dosimeters
2024 - ANTONIO, P.L.; SILVA, A.M.B.; SILVEIRA, I.S.; CALDAS, L.V.
Some solid-state materials store energy in the form of trapped electronic charges, when they are exposed to ionizing radiation. This energy can be measured when the stimulation of those charges occurs and one way is the heating of the sample, in order to observe its luminescent signal by the thermoluminescence (TL) technique. Another way to study the luminescence of these materials is by means of the phototransferred thermoluminescence (PTTL) technique, that allows the observation of the light-induced transfer of charges from one kind of trap to another [1-2]. The main objective of this work was to study the TL and PTTL of radiation dosimeters in 60Co and UV beams, in order to apply these dosimeters using an established photo-transfer procedure in high-dose dosimetry. The luminescent responses of commercial LiF:Mg,Ti, CaF2:Dy, CaF2:Mn and CaSO4:Dy dosimeters were studied according to this sequence: 1) TL after irradiation; 2) TL after irradiation and post-irradiation thermal treatment (PITT); and 3) PTTL after irradiation, PITT and illumination. The irradiations were performed using a 60Co source, and all the measurements were taken using the Risø reader system, model TL/OSL-DA-20. The absorbed doses were: 0.7 Gy (LiF:Mg,Ti and CaSO4:Dy), 20 Gy (CaF2:Dy) and 50 Gy (CaF2:Mn), for the first step, and 5 Gy (LiF:Mg,Ti), 100 Gy (CaF2:Dy), 200 Gy (CaF2:Mn) and 25 Gy (CaSO4:Dy), for the second and third steps. As results of the first step, TL emission maximum peaks were observed for all four materials at about 250ºC (LiF:Mg,Ti), 300ºC (CaF2:Dy and CaSO4:Dy) and 385ºC (CaF2:Mn). After PITT, in the second step of the experiments, the TL peaks arised at about 365ºC for LiF:Mg,Ti, and for the other materials no peaks were observed. In the final step, after exposure to UV light, PTTL signals appeared for LiF:Mg,Ti at 260ºC and 370ºC, for CaF2:Mn at 398ºC and for CaSO4:Dy at 200ºC; no PTTL was observed for CaF2:Dy. According to the results obtained, it was possible to study the occurrence of the phototransferrence signal of the materials, present for LiF:Mg,Ti, CaF2:Mn and CaSO4:Dy. These data open the possibility of applying these materials and the PTTL technique in high-dose dosimetry of gamma irradiators, with applications in the industrial area.
CaSO4:Ce,Mn: A novel, highly sensitive TL/OSL phosphor synthesized via the slow evaporation method
2024 - SILVA, A.M.B.; ANTONIO, P.L.; JUNOT, D.O.; CALDAS, L.V.D.; SOUZA, D.N.
In this study, a new CaSO4 crystal doped with cerium and manganese is described and its potential for dosimetric applications is evaluated. Cerium and manganese were incorporated into CaSO4 at a concentration of 0.1 mol% each. The crystal growth parameters were established based on previous studies [1-2], utilizing the slow evaporation route and were prepared in pellet form with the addition of Teflon. The crystalline structure and optical properties of the crystals were analyzed using X-ray diffraction (XRD) and photoluminescence (PL) techniques. In addition, thermoluminescence (TL) and optically stimulated luminescence (OSL) were used to comprehensively investigate the dosimetric properties of the phosphors, such as the TL glow curve and continuous wave OSL (CWOSL) curves, dose-response and its reproducibility, fading, sensitivity, variation of TL intensity with the heating rate, correlation between TL and OSL emissions, and determination of the minimum detectable dose (MDD). The phosphor was synthesized efficiently using a slow evaporation route, with results from both PL and TL emission spectra confirming the presence of dopant ions in the crystal matrix. At a heating rate of 5 °C/s, the CaSO4:Ce,Mn samples exhibited a TL emission curve at 145°C, characterized by three overlapping peaks. The samples showed a typical exponential OSL decay curve with a predominant fast decay component, indicating that the charge traps have a high photoionization cross-section for blue LEDs. The luminescent signals exhibited linearity and reproducibility within the investigated dose range (169 mGy–100 Gy). Furthermore, the incorporation of cerium as a co-dopant in the CaSO4:Mn matrix resulted in a notable increase in TL/OSL sensitivity, showing potential compared to mono-doped CaSO4 dosimeters [2] and commercially available alternatives.
Analysis of the correction factor for the effect of the volumetric average using thermoluminescent dosimeters
2024 - ALMEIDA, S.B.; CUNHA, A. P. V.; SAMPAIO, C. C.; CAMPOS, L.L.
Among the dosimetry complexities of making use of small fields, the volume average correction factor is an essential factor for analysis. This factor is defined as the ratio between the dose absorbed in water at the reference point of the water phantom in the absence of the detector and the average dose absorbed over the sensitive volume of the detector (still in the absence of the detector). This occurs because the detector has a significant volume, having the potential to influence dosimetry depending on the region that has a high dose gradient or the size of the field that is intended to be measured (1,2,3). The objective of this work was to analyze the volumetric mean factor using TLDs (LiF:Mg,Ti; µLiF:Mg,Ti; CaSO4:Dy). To develop the effect of the volumetric average, some parameters are necessary, such as: the dimensions of the dosimeters and the profiles of the radiation beam. Due to the geometry of the dosimeters or detector used, it is necessary to take into account the weight function, w(x,y)(2). This parameter should approximate the dosimeter to a detector shape, such as: line, cylinder, cylinder with central electrode or a circular shape. In this work, the dosimeters were approximated to a detector with a circular shape like the diode, due to the face of the dosimeter facing the central beam of the linear accelerator. To be used the beam profiles were approximated to a Gaussian distribution that was obtained by the graphics program origin, in version 9.0. To calculate the volumetric average, a code developed by Cunha, 2019 using the Scilab software, version 6.0, was used. The fields analyzed were 2 x2 cm2 ; 1 x 1 cm2 and 0,5 x 0,5 cm2. The results obtained demonstrated that the µLiF was the dosimeter that had the least influence on the fields, showing an influence of only 2% in the 0.5 x 0.5 cm2 field, being considered the best detector for small field dosimetry. The LiF:Mg,Ti dosimeter showed a significant influence of 8% in the 1 x 1 cm2 field. CaSO4:Dy had an influence of 60% and is not recommended for use in fields smaller than 1 x 1 cm2.
Tribo-corrosion evaluation of electron beam melting Ti6Al4V-ELI for biomedical applications
2023 - NEVES, M.D.M das; SILVA, L.C.E.; ANTUNES, R.A.; ÁGUA, F.P da; PAZ, J.O da; PIERETTI, E.F.
Biomaterials surfaces need to be adequate to the function they perform; for this reason, the importance of studying surface finish increases as design requirements grow, regarding geometry and precision requirements in bioengineered materials. These biomaterials are subject to several types of premature failure, such as wear, fatigue, micro movements, particle detachment and degradation, which may generate the need for new interventions [1]. Titanium alloys have been widely used in the production of biomaterials due to their high physicochemical stability, mechanical resistance and biocompatibility. Currently, a route widely used on the implants production is the additive manufacturing using Selective Laser Melting (FSL) technology and Electron Beam Melting (EBM). The surfaces built by these technologies are covered with a certain amount of adhered material, which is partially melted on its surface, being a disadvantage in melting techniques using a bed of particulate materials, where a very smooth and low roughness surface cannot be achieved [2]. Additionally, surface characteristics are still influenced by the process parameters used in consolidation, in particular: power, speed, movement directions of the laser beam and other parameters. The objective of this work was to evaluate the tribological and corrosion behavior of electron beam melting Ti6Al4V samples. Titanium alloy samples was produced with Ti6Al4V-ELI (extra low interstitials) powder by electron beam melting technique, at 5 differrent speed parameters. Confocal microscopy was also used to evaluate samples roughness and topography. The tribo-corrosion tests were carried out during 10 min, solid spheres of 52- 100 chrome steel, with 10 mm in diameter, were used as counter-bodies. The electrolyte used to simulate body fluids was Ringer´s solution at 37ºC. Current density and open circuit potential versus time were monitored throughout the test. There is a tendency towards an increase in friction force values according to the surface topography. The results indicated that the tribo-corrosion behavior is influenced by the Ti6Al4V-ELI surfaces finishing, and the wear rate is dependent of the normal force and the roughness of each sample; which is closely linked to the change in the speed parameters used in the preparation of the samples. Therefore, it is necessary to constantly advance research on the use of electron beam melting for biomaterials surfaces produced with titanium powder alloys.
Avaliação preliminar sobre a biodistribuição de arsênio em peixes de uma área de proteção ambiental marinha no litoral sul de São Paulo
2023 - AZEVEDO, JULIANA de S.; MIRANDA, LARISSA Y.; BRAGA, ELISABETE de S.; SARKIS, JORGE E. de S.; HORTELLANI, MARCOS A.
O arsênio (As) é um metalóide que em sua forma inorgânica possui elevada toxicidade. Apesar de não possuir função biológica, é facilmente assimilado pelos organismos marinhos. Em animais como peixes e crustáceos, a forma orgânica do arsênio, menos tóxica, prevalece sob a inorgânica, como forma de regular o estresse osmótico dos organismos expostos a altas concentrações deste elemento. O Complexo Estuarino-Lagunar de Cananéia-Iguape (CELCI), está inserido na Área de Proteção Ambiental Cananéia-Iguape-Peruíbe, localizada no litoral sul do estado de Saulo. A região norte do CELCI está submetida a estressores ambientais relacionados a abertura do canal do Valo Grande, que favorece o ingresso de diversos materiais continentais, a partir do rio Ribeira de Iguape, podendo alterar a dinâmica abiótica e biótica da região. Deste modo, a investigação de elementos potencialmente tóxicos e que sejam modulados por fatores ambientais como a salinidade, torna-se de fundamental importância para a conservação de espécies aquáticas residentes do CELCI. Este estudo buscou investigar a biodistribuição do arsênio inorgânico em peixes com importância ecológica e econômica no CELCI, a saber: Bagre amarelo (Aspistor luniscutis e Cathorops spiixi); Bagre urutu (Genidens genidens), Linguado (Achirus lineatus), Robalo îexa (Centropomus undecimalis), Caratinga (Diapterus rhombeus), Baiacu pintado (Sphoeroides testudineus) e Tainha (Mugil curema). As coletas foram feitas em novembro de 2021, em quatro pontos ao longo do CELCI, em um gradiente de maior (setor sul) para menor salinidade (setor norte), e em agosto de 2022 no rio Olaria, um sistema fluvial que desagua no estuário. 19 peixes foram capturados e dissecados para obtenção do tecido muscular, brânquias e do fígado. Assim, 57 amostras foram submetidas a digestão ácida (HNO3 e H2O2) em forno de micro-ondas, com posterior diluição para análise de As (AsO91) por espectrometria de massa com plasma indutivamente acoplado (ICP-MS). Os limites de detecção (LD) e quantificação (LQ) obtidos foram 0,1 ng g-1 e 0,2 ng g-1, respectivamente. O controle de qualidade foi assegurado a partir da análise dos materiais de referência Dorm-4 (Dogfish muscle) e DOLT-2 (Dogfish liver), com As certificado em 6,80±0,64 μg g-1 e 16,6±6,1 μg g-1, respectivamente. Os resultados analíticos obtidos mostraram boa precisão e exatidão, com uma recuperação de 102% (DOLT-2) e 104% (DORM-4). Os teores de As obtidos nos peixes mostraram uma ordem de concentração nos tecidos analisados similar no setor norte (músculo~fígado>brânquias) e no rio Olaria (fígado>músculo>brânquias), enquanto no setor sul, a tendência de concentração foi diferente (brânquias>músculo>fígado>). Tal diferença pode estar relacionada com a salinidade, visto que os peixes do setor sul apresentaram maiores concentrações médias de As nas brânquias quando comparado com os demais tecidos (brânquias: 2,681±3,091 μg g-1; músculo: 2,394±2,348 μg g-1; fígado: 2,051±1,779 μg g-1). Quanto à distribuição de As nos peixes do setor norte (brânquias: 0,491±0,570 μg g-1; músculo: 0,907±0,689 μg g-1; fígado: 0,902±0,464 μg g-1) e no rio Olaria (brânquias: 1,309±0,361 μg g-1; músculo: 1,623±0,847 μg g-1; fígado: 3,597±1,711 μg g-1), os resultados obtidos sugerem que o fígado e as brânquias possuem indícios de processos de bioacumulação, e as condições ambientais dos pontos de coletas podem influenciar nas exposições dos animais.
Hydrogen mitigation
2024 - DE MICHELI, LORENZO; SILVESTRIN, G.; SOUZA, R.F.B. de; NETO, A.O.; GIOVEDI, C.
In the context of discussions surrounding the hydrogen economy, particularly its green aspects, ensuring safety in the production and storage of hydrogen is paramount. This is especially crucial when hydrogen mixes with air, comprising between 6% and 30% in volume, as it poses potential risks of explosions. A proven method to mitigate these dangers is the utilization of Passive Autocatalytic Recombiners (PARs). These devices facilitate the recombination of hydrogen with oxygen on active catalytic surfaces, leading to the generation of water vapour and heat [1], reducing significantly the risk of explosions. PARs are typically composed of materials like stainless steel, alumina, and silica, which support active catalytic elements such as platinum or palladium. To combat catalyst deactivation resulting from water accumulation, researchers have explored the use of hydrophobic materials [2], among which graphene stands out. Recent studies have demonstrated that graphene could be successfully applied directly on surface, [3], using a non-thermal plasma system. This method resulted in the production of a material with few layers and hexagonal structural defects, making it attractive due to its simplicity, low cost, and scalability. In this sense, graphene is a promising option fto be applied as hydrophobic coating in catalysts for PARs. This work investigated the formation of films of graphenoid materials doped with platinum or palladium on a sintered porous metal filter in a single step. X-ray diffraction experiments revealed high amorficity, with percentages of approximately 49.6% and 60.0% for materials containing platinum or palladium, respectively. The D1/G band ratios were 2.9 and 1.6 for materials with platinum or palladium, indicating the presence of structural defects. Contact angle measurements demonstrated strong hydrophobicity for both materials, with values of 124º and 119º, respectively. Catalytic tests showed that the palladium-based converter was able to remove 17% of the injected hydrogen, while the material containing platinum achieved a removal of around 23%, confirming the effectiveness of these coatings in converting hydrogen into water. The experimental results indicated that coating porous steel filters with graphene doped with catalytic metals represents a promising strategy to ensure safety and efficiency in converting hydrogen into green energy systems. This approach has significant implications for sustainability and corporate social responsibility practices.
The radioactive seed localization and wire guided localization for impalpable breast cancer surgery
2023 - FERREIRA, HORTENCIA; ROSTELATO, MARIA E.C.M.
Introduction: Impalpable breast cancer requires an intraoperative localization to guide the surgical procedure. The radioactive seed localization (RSL) technique uses the radioactive lodine-125 seed, while wire guided localization (WGL) uses a metallic wire as a marker, implanting at the lesion site. The conservative surgery success depends on the tumor's complete excision with negative surgical margins. The objective of this study is to perform a meta-analysis of the surgical efficiency of both techniques, evaluating the rates of positive surgical margins, reoperation, and recurrence. Methods: The systematic research was performed in PubMed, Embase, LILACS, SciELO, and Web of Science. The terms impalpable breast cancer, breast surgery, radioactive seed localization, and wire-guided localization, were used for the search strategy. The selected studies went through a standard form of data extraction. The risk of bias tools, ROBINS-1 and ROB-2, were applied to analyze the bias risk and methodological quality. The Review Manager 5.4 software was used to perform the meta-analysis by the random effects analysis model. Results: Six randomized controlled trials and 32 cohort studies were included. The evidence overall quality was high for randomized trials and moderate for cohort studies. The population consists of women with non-palpable breast cancer, aged 22 to 92 years old. The results demonstrated an RSL superiority over WGL for the rates of positive surgical margin (relative risk (RR) 0.78, 95% confidence interval [Cl]:0.70,0.88, 15,085 patients), reoperation (RR 0.71, 95% C1:0.61,0.84, 13,884 patients) and recurrence (RR 0.41, 95% CI:0.19,0.86, 1,525 patients, followed up for a period of 13-109 months). Conclusions: The RSL technique is a valid and superior localization method for surgical efficiency for patients with non- palpable breast cancer and can be applied in various indications for breast-conserving surgery with intraoperative localization. Furthermore, the longer interval between seed implant and surgery, due to the physical half-life of lodine-125 is 59.4 days, offers greater organization flexibility to the radiology and surgery sectors, and to providing safety to those who undergo RSL before neoadjuvant chemotherapy and achieve a complete pathological response.
Status and development of a high-power laser facility at IPEN
2024 - SAMAD, R.E.; BONATTO, A.; VIEIRA JUNIOR, N.D.
IPEN's Center for Lasers and Applications utilized laser pulses produced by a hybrid Ti:Sapphire/Cr:LiSAF CPA system. The CPA frontend is a Quantronix Odin laser that generates 50 fs, 1 mJ pulses at 1 kHz. The system has been modified to allow the extraction of the amplified, uncompressed pulses, which are then sent to an in-house, custom-designed Cr:LiSAF multipass amplifier [1,2] and compressor, generating up to 0.5 TW pulses at 5 Hz. This system is shown in Fig. 1, and is being upgraded replacing the Cr:LiSAF by a multipass Ti:sapphire amplifier, aiming to obtain near-TW pulses at 10 Hz. As a first target, the upgraded system will aim to investigate the production of medical radioisotopes by photonuclear reactions triggered by Bremsstrahlung gamma photons from electrons; IPEN is developing a laser wakefield accelerator (LWFA) – potentially the first one in Brazil –, to initially operate in the self-modulated regime (SM-LWFA). With this goal, multiple subjects related to the SM-LWFA are being addressed ranging from theoretical works and PIC simulations [3] to the in-house development of de Laval nozzles [4], and plasma diagnostics [5]. Currently, IPEN intends to establish a high-intensity, multi-user laser facility that will be equipped with a 15 TW, 35 fs pulse laser system at 10 Hz. The system will be modular, featuring a main oscillator, a temporal stretcher, a regenerative and 2 multipass amplification stages, and a pulse compressor, capable of being upgraded to 30 TW. The system, the experimental setup and the diagnostics are designed to be versatile, prepared for supporting particle accelerations processes and even extreme conditions, a platform for multi-users experiments.
Influence of the solid-state reaction method on copper vanadate samples
2024 - CORREA, DENILSON C.; COSTA, CLEIDILANE S.; PASCA, GABRIEL A.C.; BENTES, BEATRIZ A.; SILVA, CRYSTIAN W.C. da; CARBONARI, ARTUR W.
Copper Vanadate is a material used in various fields [1]. To synthesize this material in a single phase, two samples of CuO were mixed with V2O5 by solid-state reaction. The annealing time was varied for each sample: 12 hours for the first (A1) and 15 hours for the second (A2), both at 700°C. The XRD results show that sample A1 formed Cu2V2O7 (52.1%), Cu2 . 3 2V4O1 1 (27.1%) and Cu3V2O8 (20.8%). Sample A2 formed Cu2V2O7 (41.6%), Cu3V2O8 (30.5%) and Cu2.32V4O11 (27.9%). The estimated crystallite were 104 nm (A1) and 103 nm (A2). The difficulty in obtaining pure samples of copper vanadate can be related to several factors, including the initial composition of the precursors [2] and the solid-state reaction method, which can affect the stoichiometry because it requires heat treatment at high temperatures, which can result in multiple phases [2]. The difficulty in obtaining pure samples of copper vanadate, regardless of the synthesis method used, is widely acknowledged in the literature [3]. It should be emphasized that this study aims to contribute to understanding the processes of synthesis and formation of copper vanadate phases.
Influence of the solid-state reaction method on nickel vanadate samples
2024 - CORREA, DENILSON C.; ANTUNES, MAIARA P.; COSTA, CLEIDILANE S.; PASCA, GABRIEL A.C.; BENTES, BEATRIZ A.; SILVA, CRYSTIAN W.C. da; CARBONARI, ARTUR W.
Nickel vanadate is a material increasingly used in sensors, batteries and other applications. This work aims to obtain and stabilize nickel vanadates using the solid-state reaction method. Three samples were synthed. Sample BI was annealed at 700°C and samples BII and BIII at 800°C, all for 6 hours. The XRD results show that all the samples formed the Ni3V2O8 phase, with an average crystallite of 112 nm for BI and 114 nm for BII and BIII. The SEM data show that sample BI has spherical grains with an average of 0.573 μm, while samples BII and BIII have rectangular grains with an of 3 μm. Given these results, the solid-state reaction synthesis showed promising results for nickel vanadate [1]. It is hoped that this work will contribute to turther research into these materials.
Lanthanum
2024 - QUEIROZ, CARLOS A. da S.
The following studies are presented: Preparation of lanthanum oxide for use as spec pure standard and synthesis and characterization of lanthanum peroxide. Using the fraction precipitation and cationic ion exchange techniques, with EDTA as eluent, it was possible to obtain pure lanthanum oxide ≥ 99.9%, whose Impurities were in the same level as in the imported standard. The yield for the combined techniques was reasonable high (≥ 80%). The raw material in the form of mixed rare earth carbonate (La2O3 45%) comes from by commercial rare earth concentrate. Emphasis was given to the analytical control to assure the purity of La2O2≥99.9% by spectrophotometry and mass spectrometry. A study was made for the optimization of dissolution lanthanum carbonate, from the lanthanum spec pure standard obtained here, as function of the concentration of ammonium carbonate and ammonium carbonate\ammonium hydroxide searching the maximum solubilization of the lanthanum carbonate. The lanthanum peroxide was prepared by the addition of hydrogen peroxide to the complexed soluble lanthanum carbonate. These studies included also the determination of active oxygen, the total lanthanum oxide by gravimetry and complexometry and the C, H, O contents by microanalysis. The peroxide was also investigated by infrared spectroscopy and thermal analysis. The analytical data collected allowed to conclude that the stoichiometric formula for the peroxide is La2O2(CO3)2 1.25H2O.
Photocatalytic performance of Ag-TiO2 films under visible light
2024 - SANTOS, DAVI R. dos; COTINHO, SAMUEL P.; OLIVEIRA, LEANDRO da S.; GODOI, CAMILA; PILLIS, MARINA F.
Water pollution caused by the disposal of organic substances such as dyes, pesticides and antibiotics seriously affects the quality of water resources and, consequently, human health. Advanced oxidative processes present themselves as an effective alternative for removing these contaminants from water. In this work, the photocatalysis performance of Ag-TiO2 films under visible light in the removal of methyl orange dye was studied. The films were obtained from a solution containing titanium isopropoxide (IV) and ethyl alcohol in a ratio of 1:10 (v:v). The solution was kept under constant stirring at 70 °C for 60 min. Subsequently, the sol was deposited on borosilicate glass using an airbrush. The films were heat treated for 30 minutes at 500 ºC in a muffle furnace and then immersed for 30 minutes in an aqueous solution of 0.1 mol.L-1 of AgNO3, followed by rinsing in deionized water and drying. After that, these films were subjected to UVC radiation for periods of 60, 90, 120 and 150 minutes to allow the reduction of Ag+ to Ag0. X-ray diffraction and scanning electron microscopy techniques were used to characterize the films. In the photocatalysis tests, it was observed that the longer the irradiation time of the catalyst in UVC light, the better its photocatalytic performance, quantified by spectrophotometry, considering the discoloration of the methyl orange dye (5 mg.L-1). The best performance was attributed to the film subjected to 120 minutes of exposure to UVC light, reaching 80% of degradation after 300 minutes of exposure to visible light.
Enhanced photocatalytic performance of titanium dioxide-carbon composite coatings embedded with silver nanoparticles
2024 - SANTOS, CAMILA M.G.
In the quest for efficient solutions for environmental remediation, titanium dioxide-carbon (TiO2-C) composite coatings with silver have emerged as promising candidates due to their nanostructural, morphological, and photocatalytic properties under visible light irradiation[1]. This study investigates the synthesis, characterization, and photocatalytic performance of these coatings, produced using the sol-gel technique followed by heat treatment at 500°C for 30 minutes. The uniform application of the coatings onto a glass substrate was confirmed through scanning electron microscopy (SEM) analysis, which demonstrated a homogeneous dispersion of the metal across the expanded graphite surface.The integration of silver into the coatings, achieved through immersion in a silver nitrate solution and subsequent exposure to ultraviolet (UV) light, resulted in a significant enhancement of photocatalytic activity. Photocatalysis curves showed up to 80% degradation of methyl orange dye under visible light irradiation over a period of six hours, with substantial degradation observed within the first two hours. This rapid degradation kinetics underscores the practical potential of these coatings in wastewater treatment and environmental remediation processes.The characterization techniques employed, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy, provided insights into the crystal structure, chemical composition, and functional groups present in the coatings. The results indicate the successful incorporation of silver into the TiO2-C matrix, which may lead to the formation of silver nanoparticles or silver oxide species, known for their photocatalytic properties.In conclusion, the comprehensive analysis of the TiO2-C composite coatings embedded with silver suggests their potential as efficient photocatalysts for environmental remediation applications.
Investigation of site-selective luminescence on core-shell persistent phosphors using synchrotron radiation
2024 - FRANCISCO, LEONARDO H.C.; MOREIRA, RENAN P.; BRITO, HERMI F.; MALTA, OSCAR L.; FELINTO, MARIA C.F. da C.
With the growing interest in the development of multifunctional luminescent nanomaterials for applications in energy conversion and storage, several new methods have been studied for the fabrication of efficient core-shell persistent phosphors with long-lasting persistent luminescence in the visible and near-infrared range. Such materials often exhibit particular optical properties that may be precisely tuned via the modification of structural parameters and surface functionalization. [1-3] Hence, in this work, site-selective luminescence of core-shell green-emitting rare-earth-doped strontium aluminate persistent phosphors functionalized with europium β-diketonate (tta, dbm) complexes were investigated utilizing a combination of synchrotron-based techniques at the CARNAÚBA beamline of Sirius, such as X-ray absorption near edge structure (XANES), X-ray Excited Optical Luminescence (XEOL), and X-ray fluorescence (XRF). X-ray excited luminescence spectroscopy revealed that single-shell materials exhibit distinct emission profiles associated with energy-transfer mechanisms via the “antenna effect” for the different β-diketonate ligands, while double-shell materials showed that the ratio between Eu2+ (green) and Eu3+ (red) emission is intrinsically different for the edge and the bulk of the studied particles. Promising results also revealed the influence of shell thickness and distance in potential energy-transfer processes, outlining an important framework for the development of multifunctional persistent phosphors utilizing rare-earth complexes as luminescent sensitizers.
Molybdenum (II) acetate as a precursor for molybdenum trioxide
2024 - SOUZA, KATIUSSE S. de; SILVA, CRYSTIAN W.C. da; BURIMOVA, ANASTASIA; PEREIRA, LUCIANO F.; OTUBO, LARISSA; CARBONARI, ARTUR W.; FREITAS, RAFAEL S. de
Transition metal structures (such as cobalt, nickel, and molybdenium) have been the subject of studies in recent years due to their electrical, catalytic and magnetic properties. Orthorhombic molybdenum trioxide (α-MoO3) is relevant because it is an antioxidant material, leading to its catalytic properties that are influenced by the valence state of molybdenum ions and the local environment where they are inserted. These structures have been investigated in developments of sensors, energy storage and the formulation of gels for the treatment of chronic diseases [1]. In this perspective, the present work proposes the use of the molybdenum (II) acetate as a metallic precursor for obtaining α-MoO3 structures by the thermal decomposition method [2]. The Mo (II) acetate belongs to a group of metal complexes composed of two highly correlated Mo ions, in which each cations are connected to complexes containing oxygen. This reagent could favor, in specific chemical route, the crystallization of MoxOy [2][3]. The syntheses yields were characterized by X-ray diffraction (XDR), scanning electron microscopy (SEM), and energy-dispersive analysis (EDS). The X-ray diffraction results suggested α-MoO3 crystallite of the 77 nm (by the Scherrer equation). By means of microscopy analysis were observed that the obtained morphology is microrod-like, with a of approximately 774 nm and a length of the 37 micrometers. The EDS analysis only showed energies related to molybdenum (Mo) and oxygen (O), confirming the purity of the obtained material.

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