Abstract: Titanium Nitride (TiN) films were obtained using the grid-assisted magnetron sputtering deposition technique on Al substrates in two conditions: under constant and variable nitrogen concentration along the thin solid film thickness. The formation of a film with variable N concentration (herein referred as graded film) was confirmed using energy filtered transmission electron microscopy, X-ray photoelectron spectroscopy and grazing incidence X-ray diffraction. The TiN thin films microstructures were also analysed using scanning and transmission electron microscopies (SEM and TEM). The viability of synthesizing TiN thin films with variable N concentration is herein proposed as an alternative method for tailoring the properties of such functional coating materials.

Palavras-Chave: titanium nitrides; tin; thin films; transmission electron microscopy; electron microscopy; x-ray photoelectron spectroscopy; magnetrons; microstructure; scanning electron microscopy

SILVA, F.C. da; TUNES, M.A.; EDMONDSON, P.D.; LIMA, N.B.; SAGÁS, J.C.; FONTANA, L.C.; SCHÖN, C.G. Grid-assisted magnetron sputtering deposition of nitrogen graded TiN thin films. SN Applied Sciences, v. 2, n. 5, 2020. DOI: 10.1007/s42452-020-2617-3. Disponível em: http://repositorio.ipen.br/handle/123456789/31448. Acesso em: $DATA.

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Abstract: Pd/C, PdAu/C, PdCu/C, and PdTiO2/ C electrocatalysts were prepared by a sodium borohydride reduction process for methane activation at low temperatures in a PEMFC reactor. These electrocatalysts were characterized by XRD, TEM, XPS, ICP-MS, ATR-FTIR, and cyclic voltammetry. The diffractograms of Pd/C, PdAu(50:50)/C, PdCu(50:50)/C, and PdTiO2( 50:50)/C electrocatalysts showed peaks associated with Pd face-centered cubic structure. PdAu(50:50)/C showed a small shift in the peak center when it was compared to Pd/C, while PdCu(50:50)/C showed a shift to higher angles when it was also compared to Pd/C. This effect can be due to the formation of an alloy between Pd and Au, and Pd and Cu. By TEM experiments, a mean nanoparticle size was observed between 6.9 and 8.9 nm for all electrocatalysts. Cyclic voltammograms of Pd/C, PdAu/C, PdCu/C and PdTiO2/ C electrocatalysts showed an increase in current density values after the adsorption of methane The ATR-FTIR experiments showed for all electrocatalysts the formation of methanol and formic acidic. Polarization curves at 80 °C acquired in a PEMFC reactor showed that PdAu(50:50)/C and PdTiO2( 50:50)/C had superior performance when compared to Pd/C, indicating the beneficial effect of adding the co-catalyst; this behavior has been attributed to the bifunctional mechanism or electronic effect.

Palavras-Chave: methane; electrocatalysts; borohydrides; sodium compounds; binary alloy systems; palladium alloys; gold alloys; copper alloys; titanium oxides; proton exchange membrane fuel cells; temperature range 0065-0273 k; fourier transformation; infrared spectra; attenuation; reflection

SOUZA, FELIPE de M.; SOUZA, RODRIGO F.B. de; BATISTA, BRUNO L.; SANTOS, MAURO C. dos; FONSECA, FABIO C.; OLIVEIRA NETO, ALMIR; NANDENHA, JULIO. Methane activation at low temperature in an acidic electrolyte using PdAu/C, PdCu/C, and PdTiO2/C electrocatalysts for PEMFC. Research on Chemical Intermediates, v. 46, n. 5, p. 2481-2496, 2020. DOI: 10.1007/s11164-020-04102-1. Disponível em: http://repositorio.ipen.br/handle/123456789/31446. Acesso em: $DATA.

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Abstract: The main goal of a 3D printed imaging phantom is to attenuate the radiation in order to differentiate tissues of the human body. This paper aims to verify the infill printing parameter in relation to its final homogeneity in printed samples. Sixteen 8 cm³ cubes with 15% to 90% infill variation, with 5% increments, were printed on PLA + Copper (Cu) and pure ABS. The samples were irradiated using a CT scan at 120 kV, 200 mA, 0.4 mm sections and reconstructed with standard filter. For each cube the mean values of Hounsfield Units (HU) and standard deviation (SD) in a Region of Interest (ROI) were determined. Visually, the internal lattice of each cube was assessed by counting line pairs per millimeter (lp/mm) using a DICOM viewer. Infill values above 50% for PLA + Cu and 55% for ABS showed a high homogeneity that does not allow line pair differentiation. In conclusion, values above and including the found percentages are recommended for use in construction of imaging phantoms.

Palavras-Chave: acrylonitrile; butadiene; computerized tomography; copper; filaments; fillers; lactic acid; phantoms; radiology; simulation; styrene; three-dimensional calculations

ANDRADE, M.A.B.; SAVI, M.; ALVES, C.O.; FIN, A.P.C.; SOARES, F.A.P.; POTIENS, M.P.A. Impact of infill percentages in visual homogeneity for 3D printed imaging phantoms. Brazilian Journal of Radiation Sciences, v. 8, n. 1A, p. 1-10, 2020. DOI: 10.15392/bjrs.v8i1A.919. Disponível em: http://repositorio.ipen.br/handle/123456789/31444. Acesso em: $DATA.

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Abstract: The purpose of this study was to evaluate the absorbed dose in the thyroid and eye lens when the patient uses individual protection. For this purpose, Monte Carlo (MC) simulation was employed using five different field of view (FOV) sizes, available in the i-Cat classic CBCT equipment. To represent the patient, a male virtual anthropomorphic phantom was used. Three different models of lead eyewear and thyroid shield were evaluated, as well as the dose difference with and without the personal protection equipment. The difference in the absorbed dose in relation to the use of the lead eyewear presented a reduction of 19% for the 8 cm×6 cm FOV (diameter×height), and 73% for the 14 cm×22 cm FOV. In relation to the thyroid, only the shield that involved the whole neck contributed to the reduction of the absorbed dose by up to 72% for a 14 cm×22 cm FOV. For the thyroid shields there was a maximum increase of 59% (14 cm×6 cm FOV), consequently, increasing the effective dose for the protocol. The results showed that the lead eyewear contributed to the protection of the eye lens, but the efficiency of the thyroid shield depends on several factors, as FOV and shield model.

Palavras-Chave: radiation protection; computerized tomography; monte carlo method; simulation; protective clothing; equipment; eyes; phantoms; neck

SOARES, MARIA R.; SANTOS, WILLIAM S.; NEVES, LUCIO P.; PERINI, ANA P.; BATISTA, WILSON O.G.; MAIA, ANA F.; BELINATO, WALMIR; CALDAS, LINDA V.E. The use of personal protection equipment for the absorbed doses of eye lens and thyroid gland in CBCT exams using Monte Carlo. Radiation Physics and Chemistry, v. 167, p. 1-6, 2020. DOI: 10.1016/j.radphyschem.2019.108347. Disponível em: http://repositorio.ipen.br/handle/123456789/31442. Acesso em: $DATA.

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Abstract: The calibration of radiation detectors is performed with the aim of ensuring accurate measurements of different types of radiation. Due to scattering neutrons, the neutron beam spectrum will not be the same spectrum as that emitted by the neutron source, thus influencing the reading of the instrument to be calibrated and causing a systematic error in the calibration of the neutron measurement devices. The objective of the present work was to estimate the contribution of scattering neutron radiation to fluence and mean energy using the Monte Carlo simulation and the Shadow-Cone Method with the objective of obtaining direct and scattering counting rates. The counting rates obtained at the Neutron Calibration Laboratory at IPEN, using the Bonner sphere spectrometer, were inserted into the NeuraLN program, which uses the UTA-4 response matrix and has 81 bins of energy used to determine the spectrum, fluence rate, and mean energy at the source-detector distances of 100 cm and 150 cm.

Palavras-Chave: monte carlo method; scattering; calibration; neutron detectors; neutron beams; neutron spectra; neutron sources; cones; shadow effect

ALVARENGA, TALLYSON S.; POLO, IVON O.; PEREIRA, WALSAN W.; CALDAS, LINDA V.E. Use of Monte Carlo simulation and the Shadow-Cone Method to evaluate the neutron scattering correction at a calibration laboratory. Radiation Physics and Chemistry, v. 170, p. 1-4, 2020. DOI: 10.1016/j.radphyschem.2019.108624. Disponível em: http://repositorio.ipen.br/handle/123456789/31440. Acesso em: $DATA.

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Abstract: In beta therapy, β particles from 90Sr+90Y are used for the prevention and treatment of ophthalmological and dermatological diseases. For such purposes, the radiation dose is deposited by planar and concave applicators positioned on the region to be treated. Although this therapy is effective on the diseases, several complications have been reported, making these types of radioactive applicators obsolete in current clinical practice. This paper proposes a methodology to prepare and evaluate the safety of a research irradiator that re-purposes and adapts dermatologic and ophthalmic 90Sr+90Y applicators. The irradiator was constructed using low cost materials and three applicator sources. The sources are positioned at the center and the upper end of acrylic rectangular prisms. Radiochromic film was used to obtain the dose distribution on the sample holder surface. Pellets of aluminum oxide doped with carbon (Al2O3:C) were used to evaluate the reproducibility of the irradiator. The MCNPX Monte Carlo code was used for the evaluation of safety conditions. The irradiator exhibits good reproducibility of irradiation of dosimeters in pellet form and is safe to handle.

Palavras-Chave: brachytherapy; strontium 90; yttrium 90; monte carlo method

SILVA, ROGERIO M.V.; BELINATO, WALMIR; SANTOS, WILLIAM S.; SOUZA, LUIZA F.; PERINI, ANA P.; NEVES, LUCIO P.; SOUZA, DIVANIZIA N. Low cost electron irradiator using 90Sr+90Y sources. Radiation Physics and Chemistry, v. 167, p. 1-8, 2020. DOI: 10.1016/j.radphyschem.2019.03.039. Disponível em: http://repositorio.ipen.br/handle/123456789/31438. Acesso em: $DATA.

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Abstract: The use of Monte Carlo simulations in dosimetry is a well established area of research, and several correction factors, for ionization chambers, were evaluated with these simulations. Some simulated values were considered even more reliable than the experimental measurements. Besides these uses with ionization chambers, Monte Carlo simulations may also be employed in the development and characterization of new dosimetric materials, as polymer gels. They are largely employed in radiotherapy dosimetry to mimic human tissue. New polymer gels were studied in order to better represent different organs or tissues, to provide more reliable results, or even to use different measurement techniques. The objective of this study was to evaluate the dosimetric properties of polymer gels, in relation to its mass-energy absorption coefficients, energy response and tissue equivalence. For this purpose the MCNPX Monte Carlo code was utilized. Three different materials, employed in radiotherapy dosimetry were evaluated in this work: MAGAS, MAGAT and AMPS. For all simulations carried out, the values were within an acceptable uncertainty and in accordance to the expected results.

Palavras-Chave: polymers; gels; dosimetry; monte carlo method; radiotherapy; ionization chambers; depth dose distributions

SANTOS, CARLA J.; SANTOS, WILLIAM S.; PERINI, ANA P.; VALERIANO, CAIO C.S.; BELINATO, WALMIR; CALDAS, LINDA V.E.; NEVES, LUCIO P. Evaluation of polymer gels using Monte Carlo simulations. Radiation Physics and Chemistry, v. 167, p. 1-4, 2020. DOI: 10.1016/j.radphyschem.2019.03.038. Disponível em: http://repositorio.ipen.br/handle/123456789/31436. Acesso em: $DATA.

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Abstract: Cone-beam computed tomography (CBCT) has been widely used in orthodontics, due to the ability to provide visualization of mineralized tissues in high definition and consequently the identification and delimitation of three-dimensional irregularities. Compared with 2D imaging techniques, the doses used in CBCT exams are higher. Considering that the pediatric and adolescent population routinely receives orthodontic treatments, it is important to note that the cellular development phase of the organs is associated with increased tissue sensitivity to radiation, and that cancer is one of the main long-term effects caused by exposure to X radiation. In recent years, the 3D printing technique has been used in the medical industry because it allows the reproduction of structures of the human body, enabling detailed studies in several application areas. The objective of this work was to study the different types of filaments available for 3D printing of structures that will compose a phantom for dose evaluation in the pediatric and adolescent population who undergo CBCT exams.

Palavras-Chave: computerized tomography; cones; dosimetry; computerized tomography; phantoms

ASSEMANY, LADYJANE P.F.; RODRIGUES JUNIOR, ORLANDO; SILVA, EZEQUIEL da; POTIENS, MARIA da P.A. Evaluation of 3D printing filaments for construction of a pediatric phantom for dosimetry in CBCT. Radiation Physics and Chemistry, v. 167, p. 1-4, 2020. DOI: 10.1016/j.radphyschem.2019.03.031. Disponível em: http://repositorio.ipen.br/handle/123456789/31434. 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: This work investigates the on-line response of a thin diode, for monitoring low dose radiation processing, with respect to the linearity between current and dose-rate, the most interesting part being the variation of the current sensitivity with the accumulated dose. The results obtained indicate that the current response of this diode is linear and quite stable with repeatability better than 0.2% and a slight decay of 5% of the current sensitivity (0.28 nA h/Gy) for doses up to 15 kGy. In an attempt to give theoretical support to these results, the radiation induced current is calculated as a function of the dose rate assuming the diode to be thin as compared with the standard values of the minority carrier diffusion lengths in intrinsic silicon. Agreement within 2% is found between calculations and experimental data.

Palavras-Chave: dose rates; radiation doses; low dose irradiation; dosimetry; silicon diodes; thin films; photodiodes; radiation monitoring

GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; BUENO, CARMEN C. Current response stability of a commercial PIN photodiode for low dose radiation processing applications. Radiation Physics and Chemistry, v. 167, p. 1-4, 2020. DOI: 10.1016/j.radphyschem.2019.04.026. Disponível em: http://repositorio.ipen.br/handle/123456789/31430. Acesso em: $DATA.

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Abstract: The craniofacial structure is three-dimensional, and for a better visualization of these structures, Computed Tomography is often employed for diagnoses, even though being a high-cost procedure, leading to increased exposure to ionizing radiation. As a consequence, studies in dosimetry are necessary, since several radiosensitive structures are located in the head and neck, such as thyroid, crystalline and salivary glands. There is an overall consensus regarding the exposure of pediatric patients to ionizing radiation, with recommendations being that the procedures must occur with the shortest exposure time as possible, and it is only prescribed when they are effectively necessary. During the procedures, radiation effects are difficult to be measured. The use of either TL or OSL dosimeters can create artifacts within the images, and the positioning of a large number of dosimeters, necessary for the correct dose evaluation, is not feasible when it comes to a pediatric patient. Therefore pediatric virtual anthropomorphic phantoms and Monte Carlo simulations were used in this work. The absorbed and effective doses were determined during an i-CAT procedure, with 5 different fields of view, utilizing 5- and 10- year-old male virtual anthropomorphic phantoms. The results pointed out that the eye lens, salivary glands and thyroid received the highest doses. Besides, the effective dose values increase with the increasing of the FOV size, and the 5-year-old male virtual anthropomorphic phantom presented the highest effective dose values.

Palavras-Chave: ionizing radiations; pediatrics; dosimetry; monte carlo method; phantoms; computerized simulation

NEVES, LUCIO P.; FRANCO, ADRIANE B.; FRANÇA, MONIQUE; SOARES, MARIA R.; BELINATO, WALMIR; SANTOS, WILLIAM S.; CALDAS, LINDA V.E.; PERINI, ANA P. Computational dosimetry in a pediatric i-CAT procedure using virtual anthropomorphic phantoms. Radiation Physics and Chemistry, v. 167, p. 1-5, 2020. DOI: 10.1016/j.radphyschem.2019.03.040. Disponível em: http://repositorio.ipen.br/handle/123456789/31428. Acesso em: $DATA.

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Abstract: The Total Skin Electron Beam (TSEB) therapy is a technique that aims to provide skin surface homogeneous absorbed dose in order to treat cutaneous T-cell lymphomas, both for curative and palliative purposes with electron beams penetrating a few millimeters into the skin, reaching the affected parts without affecting internal organs. In vivo dosimetry has become an important role for the treatment of total skin irradiation within a rigorous quality assurance. The luminescent dosimeters, such as TLDs and OSLDs, have proven to be very useful for the verification of the dose distribution and prescribed for the patient as the dose may differ from place to place due to patient body geometry, overlapping of structures and asymmetries of the radiation field. Other routine in vivo dosimetry tool is the DIODEs and they as well help validating radiation therapy dosimetry. Al2O3:C OSL pellets manufactured and marketed by REXON Components and TLD Systems have already been characterized for TSEB applications. The aim of this work is to compare the performance of Al2O3:C OSL pellets from REXON to in vivo TSEB dosimetry with silicon DIODEs QEDTM detectors from Sun Nuclear (EUA) using an anthropometric phantom. Dosimeters and DIODEs were previously characterized for 6 MeV HDTSe- electron beams and then placed over an Anderson Rando® anthropomorphic phantom, evaluating the body dose distribution. The reference point of measurement was the umbiculous as recommended by formalism. The results showed that the Al2O3:C OSL pellets presented acceptable results, but some greater variation of the response in relation to silicon DIODEs were found due to its considerable rotational dependency.

Palavras-Chave: electron beams; skin; skin diseases; neoplasms; lymphomas; dosimetry; in vivo; aluminium oxides; carbon; phantoms; silicon diodes; external irradiation

ALMEIDA, S.B.; VILLANI, D.; SAKURABA, R.K.; REZENDE, A.C.P.; CAMPOS, L.L. Comparison between Al2O3:C pellets and DIODEs for TSEB in vivo dosimetry using an anthropomorphic phantom. Radiation Physics and Chemistry, v. 167, p. 1-4, 2020. DOI: 10.1016/j.radphyschem.2019.02.030. Disponível em: http://repositorio.ipen.br/handle/123456789/31426. Acesso em: $DATA.

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Abstract: There is a great demand for phantoms by many areas of knowledge to be used for teaching or daily work. However, commercial phantoms are expensive and hard to obtain, especially in countries going through development. As an alternative, 3D printing can be the way to produce less expensive and reliable 3D phantoms. The goal of this study is to evaluate 14 available commercial filaments, in order to find if and how they can be used in 3D printed phantoms in computed tomography. Each material was printed as a 2 cm edge cube with rectilinear pattern and 60, 80 and 100% infill. The 80% infill of five other patterns were also printed and compared. Each 100% infill cube was weighted and had its density calculated. After that, the cubes were scanned in a Philips CT Brilliance 6 with 120 kVp, 200 mA, 2 mm slices and standard reconstruction. At the center of each cube, a ~120 mm2 region of interest was set to measure the mean Hounsfield Unit (HU) and its standard deviation. The software Origin was used to plot HU results for rectilinear pattern, determine linear trends with its R2 and compare achieved values with HU tissue range from literature. To confirm the response of HU values of selected tested materials in CT imaging as a function of percentage infill, a phantom prototype of a finger was 3D printed. The HU of the tested materials ranged from −516.2 ± 7.3 to 329.8 ± 18.9. All human tissues could be mimicked making use of these materials, except cortical bone above ~350 HU and tooth parts. The most promising filament was PLA + Cu, due to the multiple infill configuration that allows the resulting HU range to represent from adipose and skin tissue to marrow bone.

Palavras-Chave: 3d printing; phantoms; fabrication; filaments; radiology; computerized tomography

SAVI, MATHEUS; ANDRADE, MARCO A.B.; POTIENS, MARIA P.A. Commercial filament testing for use in 3D printed phantoms. Radiation Physics and Chemistry, v. 174, p. 1-7, 2020. DOI: 10.1016/j.radphyschem.2020.108906. Disponível em: http://repositorio.ipen.br/handle/123456789/31424. Acesso em: $DATA.

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Abstract: The aim of this work was to produce crystals of CaSO4 doped with europium (Eu) and silver (Ag) nanoparticles, by means of three different preparation routes, and to study their applicability in radiation dosimetry by the TL and OSL techniques. The crystals were produced by variations of the slow evaporation route. Samples of CaSO4: Eu,Ag(a) were obtained using europium oxide and silver particles as dopants. For the growth of the crystals of CaSO4:Eu,Ag(b), silver was incorporated in nitrate form. CaSO4:Eu,Ag(c) phosphorus were synthetized mixing europium oxide in a colloidal suspension of silver nanoparticles. Optical characterization confirmed the presence of Eu3þ/Eu2þ in the crystal matrix. Dosimetric characteristics were evaluated after the exposure of the samples to a90Sr/90Y source. The CaSO4:Eu,Ag(a) and CaSO4:Eu,Ag(b) composites presented the most intense signals, the lowest detectable doses, and showed a linear and reproducible dose response, but the CaSO4:Eu,Ag(a) samples showed the best potential for application in TL/OSL dosimetry.

Palavras-Chave: thermoluminescence; photoluminescence; nanoparticles; dosimetry; radiation sources; synthesis; calcium sulfates; x-ray diffraction; dosemeters

JUNOT, DANILO O.; SOUZA, DIVANIZIA N.; CALDAS, LINDA V.E. TL/OSL signal of CaSO4:Eu,Ag samples produced by variations of the slow evaporation route. Radiation Measurements, v. 135, p. 1-8, 2020. DOI: 10.1016/j.radmeas.2020.106334. Disponível em: http://repositorio.ipen.br/handle/123456789/31422. Acesso em: $DATA.

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Abstract: Cell line-based research is a valuable tool for the study of cancer physiopathology and the discovery of new drugs for use in clinical practice. In this study, inductively coupled plasma mass spectrometry (ICP-MS) was used to estimate Ca, Co, Cu, Fe, K, Mg, Mn, Na, P, S, Se, and Zn in epithelial tubular cells (HK-2) and kidney tumor cells (Caki-1 cells). The most relevant difference was a decrease in the contents of Ca, Cu, Fe, K, Mg, Mn, Na, P, S, and Zn. A significant accumulation of Co was also detected in Caki-1 cells. The fold change variation of each element concentration between HK-2 and Caki-1 cells was Ca (‒0.40), Co (1.37), Cu (‒0.68), Fe (‒0.56), K (‒0.40), Mg (‒0.41), Mn (-0.54), Na (‒0.33), P (‒0.31), S (‒0.26), and Zn (‒0.73). These findings indicate that the elements mainly affect the metabolic pathways of epithelial kidney cells. Thus, our findings open a new avenue for RCC target therapy

Palavras-Chave: kidneys; carcinomas; elements; transition elements; icp mass spectroscopy; transformations; tumor cells; lyophilization

BELLINI, MARIA H.; SOUZA, ALEXANDRE L. de; SILVA, FABIO F. da; GUILHEN, SABINE N.; FERREIRA, RAFAEL V. de P.; ARAUJO, LEANDRO G. de; OLIVEIRA, JOAO E. de; MARUMO, JULIO T. Variations in essential elements after malignant transformation of kidney epithelial tubular cells. Medical & Clinical Research, v. 5, n. 6, p. 114-117, 2020. DOI: 10.33140/MCR.05.06.04. Disponível em: http://repositorio.ipen.br/handle/123456789/31420. Acesso em: $DATA.

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Abstract: This paper aims to propose an easy and fast method of optimization of the gamma-ray spectrometry counting time in determining natural radionuclides (210Pb, 212Pb, 214Pb, 212Bi, 214Bi and 228Ac) in order to minimize uncertainties in the concentration. The samples were measured by gamma-ray spectrometry with a hyper-pure germanium detector Canberra, 25% relative efficiency, effective resolution of 1.9 keV on the 1332.5 keV 60Co with associated electronics and coupled to a microcomputer. Multichannel Maestro A65-I model was used for spectrum acquisition and peak net area determination, and WinnerGamma/Interwinner 6.01 software was used for gamma-ray spectra analysis and to calculate the concentrations and associated uncertainties. The counting times used were 86,000 s and 150,000 s.

Palavras-Chave: actinium 228; bismuth 212; bismuth 214; cobalt 60; counting techniques; data covariances; gamma spectroscopy; high-purity ge detectors; lead 210; lead 212; lead 214; multi-channel analyzers; optimization

NISTI, M.B.; MADUAR, M.F.; SAUEIA, C.H.R.; CAVALCANTE, F.; MAZZILLI, B.P. Optimization of the gamma-ray spectrometry counting time based on uncertainties of radionuclides concentration in samples. Brazilian Journal of Radiation Sciences, v. 8, n. 2, p. 1-12, 2020. DOI: 10.15392/bjrs.v8i2.1197. Disponível em: http://repositorio.ipen.br/handle/123456789/31418. Acesso em: $DATA.

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Abstract: Renal cell carcinoma (RCC) represents 3% of human malignant tumors and approximately 90% of malignant renal neoplasms. Despite great therapeutic advances in the last decade, metastatic RCC (mRCC) is still considered an incurable disease. In this study, we examined the potential of essential elements as biomarkers of mRCC using an orthotropic metastatic mouse model. Frozen lung and plasma samples from healthy and mRCC-induced mice were lyophilized, digested, and analyzed using inductively coupled plasma mass spectrometry. In metastatic lungs, a significant increase in Ca concentration (268%) was observed, whereas a significant decrease in Cu (23.2%), Fe (17.4%), Mn (38.8%), and Na (11.7%) was observed. The plasma of mRCC-induced mice showed decreased concentrations of Mn (53%), Na (19.7%) and Zn (49,50%) and increased levels of Ca (53%), Cu (39.5%), Our findings revealed marked differences in the concentrations of essential elements in the lung and plasma of the metastatic mouse model. The circulating levels of Ca, Cu, Mn, Na, and Zn could be utilized as diagnostic and therapeutic response biomarkers.

Palavras-Chave: carcinomas; kidneys; biological markers; elements; metastases; icp mass spectroscopy; metabolism; tumor cells; transformations; trace amounts

BELLINI, MARIA H.; SOUZA, ALEXANDRE L. de; SILVA, FABIO F. da; GUILHEN, SABINE N.; FERREIRA, RAFAEL V. de P.; OLIVEIRA, JOAO E. de; MARUMO, JULIO T. Essential elements as biomarkers of metastatic renal cell carcinoma. Medical & Clinical Research, v. 5, n. 7, p. 143-146, 2020. DOI: 10.33140/MCR.05.07.04. Disponível em: http://repositorio.ipen.br/handle/123456789/31416. Acesso em: $DATA.

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Abstract: Ventilator-associated pneumonia (VAP) is an infection that arises after endotracheal intubation affecting patients under intensive care. The presence of the endotracheal tube (ETT) is a risk factor since it is colonized by multispecies biofilm. Antimicrobial photodynamic therapy (aPDT) could be a strategy to decontaminate ETTs. We verify if methylene blue (MB) associated with external illumination of the ETT could be an alternative to destroy biofilm. We performed an in vitro and ex vivo study. In vitro study was performed with P. aeruginosa biofilm grew over ETT for 7 days. After treatment, the surviving cells were cultured for 3 days and the biofilm was analyzed by crystal violet absorbance. Ex vivo study employed ETT obtained from extubated patients. aPDT was performed with MB (100 μM) and red LED (k = 640±20 nm). We quantified the biofilm thickness and used scanning electron microscopy and fluorescence technique to verify morphological and functional changes after aPDT. Our results showed that bacteria remain susceptible to aPDT after sequential treatments. We also attested that aPDT can reduce biofilm thickness, disrupt biofilm attachment from ETT surface and kill microbial cells. These data suggest that aPDT should be investigated to decrease VAP incidence via ETT decontamination.

Palavras-Chave: respiratory system; intratracheal administration; pneumonia; respiratory system diseases; bacteria; biological materials; microorganisms; photochemistry; patients; medicine; hospitals

SOARES, ROSANE B.; COSTA, DENIS H.; MIYAKAWA, WALTER; DELGADO, MARIA G.T.; GARCEZ, AGUINALDO S.; YOSHIMURA, TANIA M.; RIBEIRO, MARTHA S.; NUNEZ, SILVIA C. Photodynamic activity on biofilm in endotracheal tubes of patients admitted to an intensive care unit. Photochemistry and Photobiology, v. 96, n. 3, p. 618-624, 2020. SI, DOI: 10.1111/php.13239. Disponível em: http://repositorio.ipen.br/handle/123456789/31414. Acesso em: $DATA.

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Abstract: This paper presents the results of time-differential perturbed gamma–gamma angular correlation measurements of SnO2 thin films carried out in an applied magnetic field. The measurements were performed upon the implantation of Fe at 80 keV and 111In (111Cd) at 160 keV. The samples were further characterized by energydispersive X-ray spectroscopy. The hyperfine parameters were studied at room temperature with and without an applied magnetic field. The results indicate the presence of two distinct local environments for the probe nuclei. Both occupy a paramagnetic state and correspond to a substitutional Sn site in the rutile phase of SnO2 with different numbers of electrons added to SnO2:Cd0. In addition, the crystal homogeneity of the site 1 increases upon applying the magnetic field.

Palavras-Chave: tin oxides; angular correlation; gamma radiation; hyperfine structure; perturbed angular correlation; magnetic fields; thin films; x-ray spectroscopy

SCHELL, J.; DANG, T.T.; ZYABKIN, D.V.; MANSANO, R.D.; GAERTNER, D.; CARBONARI, A.W. Investigation of the local environment of SnO2 in an applied magnetic field. Physica B: Physics of Condensed Matter, v. 586, p. 1-6, 2020. DOI: 10.1016/j.physb.2020.412120. Disponível em: http://repositorio.ipen.br/handle/123456789/31412. Acesso em: $DATA.

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Abstract: Human amniotic membrane (HAM) is a biomaterial with biological properties beneficial to tissue repair, serving as a substrate for cell cultivation. Irradiation is used for tissue sterilization, but can damage the HAM structure. The objective of this paper was to construct a skin substitute, composed of human keratinocytes cultured on glycerolated HAMs, and to evaluate the influence radiation on subsequent cell culture growth. Four batches of HAMs were glycerolated, and half of them were radio-sterilzed with 25 kGy. Non-irradiated glycerolated HAM (ni-HAM) and irradiated glycerolated HAM (i-HAM) samples were then de-epithelized and analyzed using optical microscopy (Picrossirius staining), immunofluorescence and electron microscopy. Subsequently, keratinocytes were cultured on ni- and i-HAMs, and either immersed or positioned at the air-liquid interface. The basement membranes of the ni-HAM group remained intact following de-epithelialization, whereas the i-HAM group displayed no evidence or remnant presence of these membranes. Concerning the keratinocyte cultures, the ni-HAM substrate promoted the growth of multi-layered and differentiated epithelia. Keratinocytes cultured on i-HAM formed epithelium composed of three layers of stratification and discrete cell differentiation. The glycerolated HAM was compatible with cultured epithelia, demonstrating its potential as a skin substitute. Irradiation at 25 kGy caused structural damage to the amnion.

Palavras-Chave: amniotic fluid; fetal membranes; biological materials; epithelium; cell cultures; electron microscopy; skin; glycerol; ionizing radiations; keratin; cell membranes

PAGGIARO, ANDRÉ O.; MATHOR, MONICA B.; TEODORO, WALCY R.; ISAAC, CESÁR; CAPELOZZI, VERA L.; GEMPERLI, ROLF. Evaluation of radiosterilized glyercerolated amniotic membranes as a substrate for cultured human epithelial cells. Organogenesis, v. 16, n. 1, p. 27-41, 2020. DOI: 10.1080/15476278.2020.1723366. Disponível em: http://repositorio.ipen.br/handle/123456789/31410. Acesso em: $DATA.

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Abstract: The arcuate nucleus (ARH) is an important hypothalamic area for the homeostatic control of feeding and other metabolic functions. In the ARH, proopiomelanocortin- (POMC) and agouti-related peptide (AgRP)- expressing neurons play a key role in the central regulation of metabolism. These neurons are influenced by circulating factors, such as leptin and growth hormone (GH). The objective of the present study was to determine whether a direct action of GH on ARH neurons regulates the density of POMC and AgRP axonal projections to major postsynaptic targets. We studied POMC and AgRP axonal projections to the hypothalamic paraventricular (PVH), lateral (LHA) and dorsomedial (DMH) nuclei in leptin receptor (LepR)-deficient mice (Leprdb/db), GH-deficient mice (Ghrhrlit/lit) and in mice carrying specific ablations of GH receptor (GHR) either in LepR- or AgRP-expressing cells. Leprdb/db mice presented reduction in the density of POMC innervation to the PVH compared to wild-type and Ghrhrlit/lit mice. Additionally, both Leprdb/db and Ghrhrlit/lit mice showed reduced AgRP fiber density in the PVH, LHA and DMH. LepR GHR knockout mice showed decreased density of POMC innervation in the PVH and DMH, compared to control mice, whereas a reduction in the density of AgRP innervation was observed in all areas analyzed. Conversely, AgRP-specific ablation of GHR led to a significant reduction in AgRP projections to the PVH, LHA and DMH, without affecting POMC innervation. Our findings indicate that GH has direct trophic effects on the formation of POMC and AgRP axonal projections and provide additional evidence that GH regulates hypothalamic neurocircuits controlling energy homeostasis.

Palavras-Chave: hormones; peptide hormones; receptors; hypothalamus; food; intake; polypeptides; nerve cells

WASINSKI, FREDERICK; FURIGO, ISADORA C.; TEIXEIRA, PRYSCILA D.S.; RAMOS-LOBO, ANGELA M.; PERONI, CIBELE N.; BARTOLINI, PAOLO; LIST, EDWARD O.; KOPCHICK, JOHN J.; DONATO JUNIOR, JOSE. Growth hormone receptor deletion reduces the density of axonal projections from hypothalamic arcuate nucleus neurons. Neuroscience, v. 434, p. 136-147, 2020. DOI: 10.1016/j.neuroscience.2020.03.037. Disponível em: http://repositorio.ipen.br/handle/123456789/31408. Acesso em: $DATA.

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Abstract: Rice and coffee husks (raw and chemically activated) are examined as potential biosorption materials regarding their capacity to remove U (total), 241Am, and 137Cs. The physical parameters evaluated were the morphological characteristics of the biomass, real and apparent density, and surface area. Contact times for the batch experiments were 0.5, 1, 2, and 4 h, and the concentrations tested ranged between 10% of the total concentration and the radioactive waste itself without any dilution. The results were evaluated by experimental sorption capacity, ternary isotherm, and kinetics models. The kinetics results showed that equilibrium was reached after 2 h for all biomass. Raw coffee husk showed the best adsorption results in terms of maximum capacity (qmax) for all three radionuclides, which were 1.96, 39.4 × 10−6, and 46.6 × 10−9 mg g−1 for U, Am, and Cs, respectively. The biosorption process for the raw and activated rice husks was best represented by the Langmuir ternary isotherm model with two sites. For the coffee husk, in the raw and activated states, the biosorption process was best described by the modified Jain and Snoeyink ternary model. These results suggest that biosorption with these biomaterials can be applied in the treatment of liquid organic radioactive waste containing mainly uranium and americium.

Palavras-Chave: bioadsorbents; biomass; fourier transformation; infrared radiation; rice; liquid wastes; organic compounds; uranium; americium; cesium; coffee beans; gamma spectroscopy

FERREIRA, RAFAEL V. de P.; ARAUJO, LEANDRO G. de; CANEVESI, RAFAEL L.S.; SILVA, EDSON A. da; FERREIRA, EDUARDO G.A.; PALMIERI, MAURICIO C.; MARUMO, JULIO T. The use of rice and coffee husks for biosorption of U (total), 241Am, and 137Cs in radioactive liquid organic waste. Environmental Science and Pollution Research, v. 27, n. 29, p. 36651-36663, 2020. SI, DOI: 10.1007/s11356-020-09727-8. Disponível em: http://repositorio.ipen.br/handle/123456789/31406. Acesso em: $DATA.

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Abstract: Scanning electrochemical microscopy (SECM) and scanning vibrating electrode technique (SVET) were used to investigate the electrochemical behaviour of the top surface of the 2098-T351 alloy welded by friction stir welding (FSW). The SVET technique was efficient in identifying the cathodic and anodic weld regions. The welding joint (WJ), which comprises the thermomechanically affected zone (TMAZ) and the stir zone (SZ), was cathodic relative to the heated affected zone (HAZ) and the base metal (BM). The reactivities of the welding joint at the advancing side (AS) and the retreating side (RS) were analyzed and compared using SECM technique in the competition mode by monitoring the dissolved oxygen as a redox mediator in 0.005 mol L−1 NaCl solution. The RS was more electrochemically active than the AS, and these results were correlated with the microstructural features of the welded alloy.

Palavras-Chave: electrochemistry; scanning electron microscopy; friction; welding; welded joints; stirring; corrosion; corrosion resistance; electrochemical corrosion

MILAGRE, MARIANA X.; DONATUS, UYIME; MOGILI, NAGA V.; SILVA, REJANE M.P.; VIVEIROS, BARBARA V.G. de; PEREIRA, VICTOR F.; ANTUNES, RENATO A.; MACHADO, CARULINE S.C.; ARAUJO, JOAO V.S.; COSTA, ISOLDA. Galvanic and asymmetry effects on the local electrochemical behavior of the 2098-T351 alloy welded by friction stir welding. Journal of Materials Science & Technology, v. 45, p. 162-175, 2020. DOI: 10.1016/j.jmst.2019.11.016. Disponível em: http://repositorio.ipen.br/handle/123456789/31404. Acesso em: $DATA.

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Abstract: The proposal of this work was to produce and characterize CaSO4 crystals doped with terbium and silver nanoparticles for use in thermoluminescent (TL) and optically stimulated luminescent (OSL) dosimetry. The crystalline structure, morphology and optical properties of the phosphors were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and photoluminescence. The viability of the slow evaporation route used in the production was confirmed. The silver nanoparticles (Ag(NPs)) were prepared by the method proposed by Lee and Meisel and characterized by XRD and visible absorption spectroscopy (UV–Vis). The composites were obtained from the addition of Teflon to the phosphors. Through the analyses, it was observed that the presence of silver nanoparticles slightly increases the intensity of the emission of the phosphor and shifts the dosimetric TL peak from 185 °C to 310 °C, at a heating rate of 10 °C/s. The samples presented a typical exponential OSL decay curve with a very slow component (τ3 ≥ 152 s) that indicates that the traps have a low photoionization cross-section for blue LEDs. CaSO4:Tb,Ag(NP) presented a higher sensitivity to radiation than CaSO4:Tb,Ag. The lowest detectable dose (LDD) and the fading of the TL signal of the composites were also evaluated. All samples presented a luminescent signal reproducible and linear, with TL and OSL responses proportional to the absorbed doses in the range of 169 mGy to 10 Gy.

Palavras-Chave: calcium sulfates; terbium; silver; ion dosimetry; ion beams; dosimetry; thermoluminescence; photoluminescence; ionizing radiations; nanostructures; emission spectra

SILVA, ANDERSON M.B.; JUNOT, DANILO O.; CALDAS, LINDA V.E.; SOUZA, DIVANIZIA N. Structural, optical and dosimetric characterization of CaSO4:Tb, CaSO4:Tb, Ag and CaSO4:Tb,Ag(NP). Journal of Luminescence, v. 224, p. 1-12, 2020. DOI: 10.1016/j.jlumin.2020.117286. Disponível em: http://repositorio.ipen.br/handle/123456789/31402. Acesso em: $DATA.

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Abstract: In this study 2k experimental designs were used for the optimization of an instrumental neutron activation analysis method for the determination of bromine, chlorine, magnesium, manganese, potassium, sodium and vanadium in biological matrix materials. Depending on radionuclide half-lives, 23 or 24 experimental designs were used with irradiation time, sample–detector distance, counting time and sample decay time as factors. Gamma ray spectrometer, comparator mass fraction and sample mass were kept constant. Optimized irradiation and measurement conditions were established based on the experimental design results that used z-scores as response on a reference material for the various elements and experimental conditions.

Palavras-Chave: chemical state; elements; experiment design; isotope ratio; matrix materials; neutron activation analysis; neutron activation analyzers

SANTOS, UANDA P.M.; LOURENÇO, FELIPE R.; MOREIRA, EDSON G. Experimental design and z-score results are useful tools for optimizing instrumental neutron activation analysis procedures. Journal of Radioanalytical and Nuclear Chemistry, v. 325, n. 3, p. 707-718, 2020. DOI: 10.1007/s10967-020-07150-4. Disponível em: http://repositorio.ipen.br/handle/123456789/31400. Acesso em: $DATA.

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Abstract: Objectives: To synthesize and characterize brushite particles in the presence of acidic monomers (acrylic acid/ AA, citric acid/CA, and methacryloyloxyethyl phosphate/MOEP) and evaluate the effect of these particles on degree of conversion (DC), flexural strength/modulus (FS/FM) and ion release of experimental composites. Methods: Particles were synthesized by co-precipitation with monomers added to the phosphate precursor solution and characterized for monomer content, size and morphology. Composites containing 20 vol% brushite and 40 vol% reinforcing glass were tested for DC, FS and FM (after 24 h and 60 d in water), and 60-day ion release. Data were subjected to ANOVA/Tukey tests (DC) or Kruskal–Wallis/Dunn tests (FS and FM, alpha: 5%). Results: The presence of acidic monomers affected particle morphology. Monomer content on the particles was low (0.1–1.4% by mass). Composites presented similar DC. For FS/24 h, only the composite containing DCPD_AA was statistically similar to the composite containing 60 vol% of reinforcing glass (without brushite, “control”). After 60 days, all brushite-containing materials showed similar FS, statistically lower than the control composite (p<0.01). Composites containing DCPD_AA, DCPD_MOEP or DCPD_U (“unmodified”) showed statistically similar FM/24 h, higher than the control composite. After prolonged immersion, all composites were similar to the control composite, except DCPD_AA. Cumulative ion release ranged from 21 ppm to 28 ppm (calcium) and 9 ppm to 17 ppm (phosphate). Statistically significant reductions in ion release between 15 and 60 days were detected only for the composite containing DCPD_MOEP. Significance: Acidic monomers added to the synthesis affected brushite particle morphology. After 60-day storage in water, composite strength was similar among all brushite-containing composites. Ion release was sustained for 60 days and it was not affected by particle morphology.

Palavras-Chave: calcium phosphates; phosphate minerals; resins; composite materials; mechanical properties; ions; enamels; dentistry; teeth; monomers

CHIARI, MARINA D.S.; RODRIGUES, MARCELA C.; PINTO, MIRELLA F.C.; VIEIRA, DOUGLAS N.; VICHI, FLAVIO M.; VEGA, OSCAR; CHRZANOWSKI, WOJCIECH; NAGAOKA, NORIYUKI; BRAGA, ROBERTO R. Development of brushite particles synthesized in the presence of acidic monomers for dental applications. Materials Science & Engineering C, v. 116, p. 1-8, 2020. DOI: 10.1016/j.msec.2020.111178. Disponível em: http://repositorio.ipen.br/handle/123456789/31396. Acesso em: $DATA.

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Abstract: The present study investigates the evolution of the residual stresses in TWIP steels induced by manufacturing chain for the production of automotive body-in-white. Two different manufacturing routes were considered. The first route encompassed a plastic deformation prior to the welding stage, whereas the second involved the spot welding followed by a baking treatment. A convergent approach was adopted to isolate the effects of the first and final manufacturing steps. The findings showed that the plastic deformation prior to the welding stage is not annihilated by the welding thermomechanical cycle. Abrupt hardness gradients along small material fractions are observed. The residual stresses state changes, although its profile is still defined by the welding stage. The post-weld bake treatment showed to promote slight residual stresses relaxation, but it is not effective in inducing the same post-weld residual stresses state for different RSW parameters set.

Palavras-Chave: twinning; plasticity; manufacturing; chains; stresses; resistance welding; welding; steels

COLOMBO, TIAGO C.A.; REGO, RONNIE; FARIA, ALFREDO R. de; OTUBO, JORGE. Processing-induced residual stresses in TWIP steel weld spots. Materials and Manufacturing Processes, v. 35, n. 5, p. 572-578, 2020. DOI: 10426914.2020.1734619. Disponível em: http://repositorio.ipen.br/handle/123456789/31394. Acesso em: $DATA.

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Abstract: This paper reports on the preparation, characterization, and photoluminescence properties of novel hybrid materials, in which the EDTA–Ln–L complexes (where L: H2O, acac, bzac, dbm, and tta ligands, and Ln: Eu, Gd, and Tb) were covalently linked to the precursor medium molecular weight chitosan surface (CS) matrices or on the chitosan surfaces previously crosslinked with epichlorohydrin (CSech). The emission spectra of these materials were characterized by intraconfigurational-4fN transitions centred on the Eu3+ and Tb3+ ions. Some broad bands from the polymeric matrix were also observed in the emission spectra, however the relative intensities of the intraconfigurational bands increased significantly for systems containing diketonate ligands when the antenna effect became more efficient. The values of the radiative rates (Arad) were higher for crosslinked hybrid systems with epichlorohydrin, while nonradiative rates (Anrad) presented the opposite behaviour. These data contributed to an increase in the values of emission quantum efficiency (η) for crosslinked materials. The effect of the modification process and antenna ligand on the values of intensities, intensity parameters Ω2 e Ω4 of the Eu3+ complexes were also investigated. The results showed that the crosslinked biopolymer surfaces have great potential for applications in molecular devices light converters.

Palavras-Chave: edta; complexes; luminescence; biological functions; polymers; ligands; phosphorescence

COSTA, ISRAEL F.; PIRES, GILVAN P.; ESPÍNOLA, JOSÉ G.P.; BRITO, HERMI F.; FELINTO, MARIA C.F.C.; FAUSTINO, WAGNER M.; TEOTONIO, ERCULES E.S. Luminescence properties of the Ln–EDTA complexes covalently linked to the chitosan biopolymers containing β-diketonate as antenna ligands. Luminescence, v. 35, n. 3, p. 365-372, 2020. DOI: 10.1002/bio.3735. Disponível em: http://repositorio.ipen.br/handle/123456789/31392. Acesso em: $DATA.

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Abstract: Purpose: To synthesize a zirconia-toughened alumina (ZTA) composite with 85% alumina matrix reinforced by 15% zirconia and to characterize its optical and mechanical properties before and after artificial aging, to be compared with a conventional dental zirconia (3Y-TZP). Material and methods: After syntheses, ZTA and 3Y-TZP powders were uniaxially and isostatically pressed. Greenbody samples were sintered and polished to obtain 80 disc-shaped specimens per group (12 x 1 mm, ISO 6872:2015). The crystalline content and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical properties were determined by the calculation of contrast ratio (CR) and translucency parameter (TP) using reflectance data. Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength test (BFS). All analyses were conducted before and after artificial aging (20h, 134 °C, 0.22 MPa). Optical parameters and microhardness differences were evaluated through repeated-measures analysis of variance (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI). Results: The synthesis of the experimental ZTA composite was successful, with 98% of theoretical density, as shown in the SEM images. XRD patterns revealed typical zirconia and alumina crystalline phases. ZTA optical properties parameters showed no effect of aging, with a high CR and low TP values denoting a high maskingability. 3Y-TZP presented lower masking-ability and aging significantly affected its optical properties. ZTA Vickers hardness, fracture toughness and Weibull parameters, including characteristic stress and Weibull modulus were not influenced by aging, while 3Y-TZP presented a significant decrease in characteristic stress and increase in fracture toughness after aging. The ZTA probability of survival for missions of 300 and 500 MPa was estimated at ~99% validating its use for 3-unit posterior fixed dental prostheses (FDP), and no different from conventional 3Y-TZP. At high-stress mission (800 MPa) a significant decrease in probability of survival was observed for aged 3Y-TZP (84%) and for immediate and aged ZTA (73 and 82% respectively). Conclusion: The ZTA composite presented a dense microstructure, with preservation of the crystalline content, optical and mechanical properties after artificial aging, which encourages future research to validate its potential use for large span FDP.

Palavras-Chave: aluminium oxides; zirconium oxides; aging; ceramics; microstructure; optical properties; optical microscopes

BENALCAZAR JALKH, E.B.; BERGAMO, E.T.P.; MONTEIRO, K.N.; CESAR, P.F.; GENOVA, L.A.; LOPES, A.C.O.; LISBOA FILHO, P.N.; COELHO, P.G.; SANTOS, C.F.; BORTOLIN, F.; PIZA, M.M.T.; BONFANTE, E.A. Aging resistance of an experimental zirconia-toughened alumina composite for large span dental prostheses: optical and mechanical characterization. Journal of the Mechanical Behavior of Biomedical Materials, v. 104, p. 1-9, 2020. DOI: 10.1016/j.jmbbm.2020.103659. Disponível em: http://repositorio.ipen.br/handle/123456789/31390. Acesso em: $DATA.

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Abstract: The present study evaluated the main factors that influence the photocatalytic activity of titanium dioxide (TiO2) films grown by metalorganic chemical vapor deposition (MOCVD) at 400 and 500 °C, in different growth times. The photocatalytic behavior was analyzed by measuring the methyl orange dye degradation at different pH values. Structural and morphological characteristics, and the recyclability of the catalysts for several cycles were also investigated. Anatase phase was identified in all films. The higher photodegradation performances were obtained at acidic pH. The results demonstrated that the photocatalyst thickness is an important parameter in heterogenous photocatalysis. The best photocatalytic result occurred for the 395 nm-thick TiO2 film grown at 400 °C, which presented 65.3% of the dye degradation under UV light. The recyclability experiments demonstrated that the TiO2 films grown by MOCVD present a great stability after several photocatalytic cycles, which allows their practical application for water treatment with high efficiency.

Palavras-Chave: titanium oxides; chemical vapor deposition; thin films; borosilicate glass; dyes; photocatalysis; recycling; substrates

MARCELLO, BIANCA A.; CORREA, OLANDIR V.; BENTO, RODRIGO T.; PILLIS, MARINA F. Effect of growth parameters on the photocatalytic performance of TiO2 films prepared by MOCVD. Journal of the Brazilian Chemical Society, v. 31, n. 6, p. 1270-1283, 2020. DOI: 10.21577/0103-5053.20200012. Disponível em: http://repositorio.ipen.br/handle/123456789/31388. Acesso em: $DATA.

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Abstract: The present research exposes the influence of 2 mol% of Al2O3 and 2 mol% SrO in 45S5 Bioglass®-based compositions. Four compositions were produced to elucidate the difference in how both oxides influence structure and thermal behavior separately and their synergy when together. Thermal properties, crystallization tendency, and sintering behavior was evaluated by differential scanning calorimetry, hot stage microscopy, and dilatometry. Changes of medium-range structures were characterized by Qn distribution of Raman spectroscopy and evaluation of 31P, 27Al, 23Na, and 29Si environment obtained by magic angle spinning nuclear magnetic resonance. Despite Qn distribution was predominantly Q2 in all samples, the composition criteria used enabled improved processing and stabilibity characteristics. The addition of Al2O3 and SrO promoted larger sinterability parameter (Sc) which indicates better sintering behavior, the glass stability against crystallization doubled (KH) compared to 45S5 and the processing window enlarged from 106 to 171.

Palavras-Chave: glass; raman spectroscopy; aluminium oxides; strontium oxides; thermodynamic properties; crystallization; sintering; oxides

ARAUJO, MARIANA S.; SILVA, ANTONIO C.; BARTOLOMÉ, JOSÉ F.; MELLO-CASTANHO, SONIA. Structural and thermal behavior of 45S5 Bioglass®-based compositions containing alumina and strontium. Journal of the American Ceramic Society, v. 103, n. 6, p. 3620-3630, 2020. DOI: 10.1111/jace.17061. Disponível em: http://repositorio.ipen.br/handle/123456789/31386. Acesso em: $DATA.

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Abstract: We applied the ESR (Electron Spin Resonance) dating method to fossils of Notiomastodon platensis (two teeth) and Toxodontinae (two teeth) found in the fossiliferous deposit of Lajedão do Patrício, João Dourado, State of Bahia, Brazil, to identify the period of formation of this fossil accumulation. Neutron Activation Analysis was applied to determine the concentrations of the main radioisotopes in enamel, dentine and sediment. The ages found for N. platensis are 16.8 ± 2.6 ka and 12.5 ± 2.3 ka, while the ages for Toxodontinae are 9.6 ± 1 ka and 9.1 ± 1 ka. The results for Notiomastodon. platensis and Toxodontinae are similar to other fossiliferous of Brazil. The estimated maximum time-averaging for Lajedão do Patrício is 11.3 ka, indicating a long period of accumulation of skeletal remains, attributed to resedimentation and reworking. The crossing between the period of formation of fossil assemblage Lajedão do Patrício and ages of climatic variations diponible in paleoclimatic curves produced for the Quaternary of northeastern Brazil indicates different climatic and environmental conditions during the formation of the deposit.

Palavras-Chave: fossils; electron spin resonance; quaternary period; teeth; dentin; enamels; tanks; time dependence; vertebrates; sediments

FARIA, FABIO H.C.; KINOSHITA, ANGELA; CARVALHO, ISMAR de S.; ARAUJO-JUNIOR, HERMINIO I. de; PEGORIN, PRISCILA; FIGUEIREDO, ANA M.G.; BAFFA, OSWALDO. ESR dating of late Quaternary megafauna fossils from João Dourado, Bahia, Brazil. Journal of South American Earth Sciences, v. 101, p. 1-7, 2020. DOI: 10.1016/j.jsames.2020.102586. Disponível em: http://repositorio.ipen.br/handle/123456789/31384. Acesso em: $DATA.

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Abstract: The growing concern with the amount of plastic materials found in the oceans makes it necessary to develop biodegradable materials that have low toxicity to marine animals and humans, but at the same time are resistant to the actions of microorganisms such as fungi or bacteria. On the other hand, agricultural waste rich in inorganic materials (such as silica) is often discarded, while it could be reused as a source of raw material. Considering these points, sodium silicate solution extracted from sugarcane waste ash was utilized to prepare biodegradable bioplastics based on corn starch and potato starch. The starch-based bioplastics were produced by casting and characterized by several physical-chemical techniques evaluating tensile strength, elongation at break, color analyses, transparency, opacity, moisture, and biodegradation assay. Bioplastics prepared with corn starch presented better physical, mechanical, and thermal properties and optical quality than bioplastics based on potato starch. The samples called CS3 and PS3, with 5.0% glycerol, were the most resistant to tensile strengths of 0.73 and 0.36 MPa, respectively. On the other hand, the highest elongation at break values were found for the samples with 7.5% glycerol (CS9, 52.90% and PS9, 49.33%). Corn starch-based bioplastics were more thermally resistant (CS3, 152.86 °C and CS9, 135.20 °C) when compared to potato starch-based bioplastics (PS3, 140.39 °C and PS9, 127.57 °C). In general, the addition of sodium silicate solution improved the mechanical and thermal properties of both types of bioplastics. The potato starch-based bioplastics were biodegraded in 5 days, while those made from corn starch took almost 40 days. The inclusion of sodium silicate inhibited fungal growth for both corn starch and potato starch bioplastics. The results suggest that sodium silicate solution obtained from renewable sources can be incorporated into starch-based bioplastics for production of biodegradable packaging with antifungal activity.

Palavras-Chave: biodegradation; agriculture; sugar cane; agricultural wastes; bagasse; chemical composition; ashes; maize; potatoes; starch; plastics; sustainability; sodium silicates; environment; polymers

AZEVEDO, LUCIANA C. de; ROVANI, SUZIMARA; SANTOS, JONNATAN J.; DIAS, DJALMA B.; NASCIMENTO, SANDI S.; OLIVEIRA, FABIO F.; SILVA, LEONARDO G.A.; FUNGARO, DENISE A. Biodegradable films derived from corn and potato starch and study of the effect of silicate extracted from sugarcane waste ash. ACS Applied Polymer Materials, v. 2, n. 6, p. 2160-2169, 2020. DOI: 10.1021/acsapm.0c00124. Disponível em: http://repositorio.ipen.br/handle/123456789/31382. Acesso em: $DATA.

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Abstract: Microbial drug-resistance demands immediate implementation of novel therapeutic strategies. Antimicrobial photodynamic therapy (aPDT) combines the administration of a photosensitizer (PS) compound with low-irradiance light to induce photochemical reactions that yield reactive oxygen species (ROS). Since ROS react with nearly all biomolecules, aPDT offers a powerful multitarget method to avoid selection of drug-resistant strains. In this study, we assayed photodynamic inactivation under a standardized method, combining methylene blue (MB) as PS and red light, against global priority pathogens. The species tested include Acinetobacter baumannii, Klebsiella aerogenes, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus, Candida albicans and Cryptococcus neoformans. Our strain collection presents resistance to all tested antimicrobials (> 50). All drug-resistant strains were compared to their drugsensitive counterparts. Regardless of resistance phenotype, MB-aPDT presented species-specific dose-response kinetics. More than 5log10 reduction was observed within less than 75 s of illumination for A. baumannii, E. coli, E. faecium, E. faecalis and S. aureus and within less than 7 min for K. aerogenes, K. pneumoniae, P. aeruginosa, C. albicans and C. neoformans. No signs of correlations in between drug-resistance profiles and aPDT sensitivity were observed. Therefore, MB-aPDT can provide effective therapeutic protocols for a very broad spectrum of pathogens. Hence, we believe that this study represents a very important step to bring aPDT closer to implementation into mainstream medical practices.

Palavras-Chave: microbial drug resistance; photosensitivity; therapy; bacteria; antimicrobial agents; radiant flux density; light sources; inactivation

SABINO, CAETANO P.; WAINWRIGHT, MARK; RIBEIRO, MARTHA S.; SELLERA, FABIO P.; ANJOS, CAROLINA dos; BAPTISTA, MAURICIO da S.; LINCOPAN, NILTON. Global priority multidrug-resistant pathogens do not resist photodynamic therapy. Journal of Photochemistry and Photobiology B: Biology, v. 208, p. 1-9, 2020. DOI: 10.1016/j.jphotobiol.2020.111893. Disponível em: http://repositorio.ipen.br/handle/123456789/31380. Acesso em: $DATA.

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Abstract: Nafion based composites are promising materials to improve the performance of direct ethanol fuel cells. In this work, composite membranes of Nafion and titanate nanotubes functionalized with sulfonic acid groups were prepared by melt-extrusion and tested in a direct ethanol fuel cell. Far and mid infrared spectroscopies evidenced the formation of ionic bridges between the sulfonic acid groups of both functionalized nanoparticles and the ionomer. Small angle X-ray scattering measurements revealed that the melt-extrusion method leads to an uniform distribution of the inorganic phase in the ionomer matrix. Such structural analysis indicated that the improved the proton conduction properties of the composites, even with the addition of a high concentration of functionalized nanoparticles, are an outcome of the synergistic ionic network due to the hydrid organic/inorganic proton conducting phases. However, an improvement of the fuel cell performance is observed for 2.5 wt% of functionalized titanate nanotubes, which is a result of the lower ethanol crossover and the plasticizing effect of the aliphatic segments of the organic moieties grafted at the surface of the titanate nanoparticles.

Palavras-Chave: composite materials; direct ethanol fuel cells; extrusion; fourier transformation; infrared spectra; membranes; nanotubes; proton conductivity; sulfonic acids; titanates; titration

MATOS, B.R.; GOULART, C.A.; TOSCO, B.; SILVA, J.S. da; ISIDORO, R.A.; SANTIAGO, E.I.; LINARDI, M.; SCHADE, U.; PUSKAR, L.; FONSECA, F.C.; TAVARES, A.C. Properties and DEFC tests of Nafion: functionalized titanate nanotubes composite membranes prepared by melt-extrusion. Journal of Membrane Science, v. 604, p. 1-7, 2020. DOI: 10.1016/j.memsci.2020.118042. Disponível em: http://repositorio.ipen.br/handle/123456789/31378. Acesso em: $DATA.

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Abstract: The application of new commercial and industrial technologies in the fields of dosimetry and medical physics is of great interest to the scientific community, both to validate existing protocols and to develop new methodologies. The popularization of 3D printing techniques has been analyzed as a great advantage in quality control in complex treatment techniques, such as radiotherapy and the development of patient simulators. Portable dosimetry systems such as Landauer MicroStar OSL system are versatile and their use in quality control is of great importance. The aim of this paper is to compare two of the most used dose calculation algorithms used in Varian Eclipse TPS – AAA and Acuros XB – for treatment planning of multiple brain metastases using a 3D printed anthropomorphic phantom and the OSL InLight system for experimental dosimetry validation. A 3D printed anthropomorphic skull phantom was submitted to a CT scan and planed five target volumes. In order of comparison, two dose calculations were performed in the Varian Eclipse 13.6 TPS with "Alabama technique", using the Varian’s AAA and AXB algorithms, and treatment delivered with 6 MV photon beam of a Varian TrueBeam linear accelerator. Landauer nanoDot dosimeters were positioned inside each of the five target volumes planned and the experimental dosimetric results were compared with the algorithms’ calculated doses. The findings of this work indicate that ACUROS XB calculates more accurate doses compared with AAA, with all the experimental agreements better than 96.0 %, probably because of the heterogeneity corrections. The uncertainty analysis of the InLight system device is enough to sustain the dosimetric uncertainties below 3.0 %, validating the results.

Palavras-Chave: dosimetry; luminescent dosemeters; phantoms; calculation methods; algorithms; radiation doses; radiation dose distributions; radiotherapy; planning; brain; metastases

VILLANI, DANIEL; MORENO, CAROLINA dos S.; SAKURABA, ROBERTO K.; CAMPOS, LETICIA L. Application of OSL dosimetry and 3D printed phantom for comparison of calculation algorithms for VMAT treatment planning. QUARKS: Brazilian Electronic Journal of Physics, Chemistry and Material Science, v. 1, n. 1, p. 30-39, 2019. DOI: 10.34019/2674-9688.2019.v1.28227. Disponível em: http://repositorio.ipen.br/handle/123456789/31374. Acesso em: $DATA.

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Abstract: A growing community of scientists has been using neutrons in the most diverse areas of science. In order to meet the researchers demand in the areas of physics, chemistry, materials sciences, engineering, cultural heritage, biology and earth sciences, the Brazilian Multipurpose Reactor (RMB) will provide 3 thermal guides and 3 cold guides, with the installation of several instruments for materials characterization. In this study, we present a standard design requirement of two primordial instruments, namely Sabiá and Araponga. They are, respectively, cold and thermal neutron instruments and correspond to a Small-Angle Neutron Scattering (SANS) and High-Resolution Powder Neutron Diffractometer (HRPND) to be installed in the Neutron Guide Building (N02) of RMB. To provide adequate flux for both instruments, we propose here an initial investigation of the use of simple and split guides to transport neutron beams to two different instruments on the same guide. For this purpose, we use Monte Carlo simulations utilizing McStas software to check the efficiency of thermal neutron transport for different basic configuration and sources. By considering these results, it is possible to conclude that the split guide configuration is, in most cases, more efficient than cases that use transmitted neutron beams independently of source. We also verify that the employment of different coating indexes for concave and convex surfaces on curved guides is crucial, at least on simulated cases, to optimise neutron flux (intensity and divergence) and diminish facility installation cost.

Palavras-Chave: neutron guides; neutron sources; neutron transport; rmb reactor; buildings; cold neutrons; thermal neutrons; reactor instrumentation; simulators; small angle scattering; neutron diffraction; scattering; monte carlo method

SOUZA, A.P.S.; OLIVEIRA, L.P. de; YOKAICHIYA, F.; GENEZINI, F.A.; FRANCO, M.K.K.D. Neutron Guide Building instruments of the Brazilian Multipurpose Reactor (RMB) project. Journal of Instrumentation, v. 15, n. 4, p. 1-24, 2020. DOI: 10.1088/1748-0221/15/04/P04011. Disponível em: http://repositorio.ipen.br/handle/123456789/31372. Acesso em: $DATA.

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Abstract: The most common goal for rice breeding is to improve the nutritional content and to reduce toxic components. Fourteen varieties of rice were grown for this purpose in six microclimatic regions in southern Brazil. The elemental composition of rice and As-Species were measured by ICP-MS and HPLC-ICP-MS, respectively. Intraand inter-species variations of essential and non-essential elements in husked grains from an important riceproducing region in Brazil are presented. Arsenic, Cd, Co, Cu, Fe, Mg, Mn, Ni, Se, and Zn were significantly affected by the microclimatic region and the rice varieties. The only exception observed was the effect of Pb variety selection, with 35.4 % associated with random fluctuations. Varieties with both higher levels of Fe/Zn and lower levels of As/Cd were identified in all regions studied. All regions and varieties were able to produce rice with Cd<10 μg kg−1, but the Santa Vitoria do Palmar region where varieties with Cd<45 μg kg−1 were selected. Well-established varieties result in a higher daily intake of essential elements than the varieties under development. Therefore, our findings may provide information to support the selection procedures for varieties, as well as to encourage improvements in management practices between regions.

Palavras-Chave: rice; food; safety; safety analysis; arsenic; elements; cadmium; intake; nutrients; chemical composition; microclimates; cultivation; geologic structures; soils

MONTEIRO, LUCILENA R.; LANGE, CAMILA N.; FREIRE, BRUNA M.; PEDRON, TATIANA; SILVA, JULIO J.C. da; MAGALHÃES JUNIOR, ARIANO M. de; PEGORARO, CAMILA; BUSANELLO, CARLOS; BATISTA, BRUNO L. Inter- and intra-variability in the mineral content of rice varieties grown in various microclimatic regions of southern Brazil. Journal of Food Composition and Analysis, v. 92, p. 1-11, 2020. DOI: 10.1016/j.jfca.2020.103535. Disponível em: http://repositorio.ipen.br/handle/123456789/31368. Acesso em: $DATA.

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Abstract: The non-ohmic behavior of Nafion electrical properties, i. e., the thickness and potential dependent conductivity, was studied in the impedance, dielectric and conductivity representations with the use of a special through-plane sampleholder in a 4-probe array. Such measurements allowed identifying the genuine ac-to-dc conductivity crossover frequency in Nafion, which occurs for f<10-1 Hz. In addition, the minimization of the interfacial electrode/ionomer polarizations with the 4-probe setup permitted the determination of the bulk dc conductivity and dielectric constant of Nafion, which are σ~0.03 Scm-1 and ε′~106 (T=40 °Cand RH=100%), respectively. The colossal dielectric constant is shown to increase the Debye length of the electric double layer to values comparable to the membrane thickness. Therefore, the exponential increase of the proton conductivity with increasing both membrane thickness and electric potential are a result of canceling out the non-linear effects of electric double layer caused by the high dielectric permittivity of Nafion. The ac-to-dc conductivity crossover in H2/O2 fuel cell impedance curves takes place for f<100 Hz and matches with the ex situ impedance spectroscopy study in excellent agreement, revealing a striking result: the potential dependent conductivity of Nafion requires extra fuel cell overpotential to overcome the electrode/ionomer interfacial polarization representing an additional polarization loss to polymer electrolyte fuel cells.

Palavras-Chave: ionic conductivity; electric conductivity; electrical properties; fuel cells; electric fields; layers; dielectric properties; electrical properties; nonlinear problems; nmr imaging; spectroscopy

MATOS, B.R. The genuine ac-to-dc proton conductivity crossover of nafion and polymer dielectric relaxations as a fuel cell polarization loss. Journal of Electroanalytical Chemistry, v. 871, p. 1-13, 2020. DOI: 10.1016/j.jelechem.2020.114357. Disponível em: http://repositorio.ipen.br/handle/123456789/31366. Acesso em: $DATA.

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Abstract: Osteoporosis is a disease characterized by bone mineral density reduction, weakening the bone structure. Its diagnosis is performed using ionizing radiation, increasing health risk. Optical techniques are safer, due to non-ionizing radiation use, but limited to the analyses of bone tissue. This limitation may be circumvented in the oral cavity. In this work we explored the use of laser speckle imaging (LSI) to differentiate the sound and osteoporotic maxilla andmandible bones in an in vitro model. Osteoporosis lesions were simulated with acid attack. The samples were evaluated by optical profilometry and LSI, using a custom software. Two image parameters were evaluated, speckle contrast ration and patches ratio. With the speckle contrast ratio, it was possible to differentiate sound from osteoporotic tissue. From speckle patches ratio it was observed a negative correlation with the roughness parameter. LSI is a promissory technique for assessment of osteoporosis lesions on alveolar bone.

Palavras-Chave: osteoporosis; lasers; images; laser radiation; skeleton; bone tissues; diagnosis; optical properties; ionizing radiations; bone mineral density; statistical models; statistical models

AMARAL, MARCELLO M.; DEL-VALLE, MATHEUS; RAELE, MARCUS P.; DE PRETTO, LUCAS R.; ANA, PATRICIA A. Osteoporosis evaluation through full developed speckle imaging. Journal of Biophotonics, v. 13, n. 7, p. 1-9, 2020. DOI: 10.1002/jbio.202000025. Disponível em: http://repositorio.ipen.br/handle/123456789/31364. Acesso em: $DATA.

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Abstract: Gamma-ray and neutron spectra from the 18O +76Se reaction at 15.3 MeV/u were measured with the EDEN array of liquid scintillators at the LNS. The results were compared to GEANT Hadrontherapy physics list simulations in order to assess the reliability of this model for the development of theNUMENproject.Agood agreement with the shape of the experimental gamma-ray spectra and a reasonable agreement with the total count rates were obtained. The gamma spectra originated from the nuclear reactions were selected by time coincidence with the Superconducting Cyclotron radio-frequency reference signal. The random coincidence background rate was appropriately described only when the Faraday Cup, the material and geometry of the experimental hall and its contents were included in the simulationwith sufficient detail. The information on the radiation spectra is important for the adequate development of the project of the detector arrays and electronic equipment for the advanced phase of NUMEN. Since orders of magnitude larger beam intensities are planned for this phase, the random coincidence rate is also of significant importance, particularly for the performance of the G-NUMEN gamma calorimeter array.

Palavras-Chave: angular distribution; beam monitoring; coincidence spectrometry; computerized simulation; counting rates; energy spectra; external beam radiation therapy; faraday cups; g codes; gamma radiation; mev range 100-1000; neutron spectra; oxygen 18 beams; selenium 76 target