70 results on '"Lopes, Ricardo T."'
Search Results
2. MYERSIELLA MICROPS (Rio Elongated Frog). ENDOPARASITES.
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DOS SANTOS, CAIO M. S. F. F., LOPES, RICARDO T., CLEMENTE-CARVALHO, RUTE B. G., HADDAD, CÉLIO B. F., FEITOSA, RODRIGO M., DE MORAES, GILBERTO JOSÉ, DA SILVA, REINALDO JOSÉ, and DOS REIS, S. F.
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FROGS , *ENDOPARASITES , *BIOLOGICAL specimens , *HYLIDAE - Abstract
The article discusses research on the specie, "Myersiella Microps (Rio Elongated Frog)" and explores about its geographical distribution and collection of specimen, along with explores endoparasites of the species.
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- 2022
3. BRACHYCEPHALUS HERMOGENESI (Flea Toad). DIET.
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DOS SANTOS, CAIO M. S. F. F., LOPES, RICARDO T., CLEMENTE-CARVALHO, RUTE B. G., HADDAD, CÉLIO F. B., FEITOSA, RODRIGO M., DE MORAES, GILBERTO JOSÉ, DA SILVA, REINALDO JOSÉ, and DOS REIS, S. F.
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TOADS , *BIOLOGICAL specimens , *FROGS , *DIET , *FLEAS - Abstract
The article discusses research on the specie, "Brachycephalus Hermogenesi (Flea Toad)" and explores about its geographical distribution and information on the diet of Brachycephalus hermogenesi using high resolution microcomputed tomography images of a preserved museum specimen .
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- 2022
4. Brain size and shape diversification in a highly diverse South American clade of rodents (Echimyidae): a geometric morphometric and comparative phylogenetic approach.
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Villoldo, J Ariel Fernández, Verzi, Diego H, Lopes, Ricardo T, Reis, Sergio F Dos, and Perez, S Ivan
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SIZE of brain , *COMPARATIVE method , *OLFACTORY bulb , *RODENTS , *PHYLOGENETIC models , *MORPHOMETRICS - Abstract
Brain morphological variation is analysed through virtual endocasts in a highly diversified clade of caviomorph rodents belonging to the family Echimyidae. Diversification in brain size and shape is explored through geometric morphometrics and comparative phylogenetic analyses. The results indicate that brain shape is largely independent of general size and reveal different trends in brain size and shape. Fossorial Euryzygomatominae, arboreal Echimyini and the semi-aquatic Myocastorini Myocastor show high encephalization; the former with a greater contribution from the olfactory bulb and petrosal lobe, and the latter two with a larger surface area of neocortex. The Euryzygomatomyinae and Myocastorini of terrestrial habits show low encephalization with a low contribution of the neocortex. Phylogenetic comparative analyses suggest that endocranial morphological evolution would have been influenced by both phylogeny and locomotor habits. The concurrence of the best fit of the Ornstein–Uhlenbeck model and the significant phylogenetic signal in the datasets suggests the involvement of constraints on morphological diversification within the major clades, as expected under phylogenetic conservatism. This could be explained by an early establishment of a particular endocranial morphology in each major clade, which would have been maintained with relatively little change. [ABSTRACT FROM AUTHOR]
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- 2023
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5. On the impact of neutron beam divergence and scattering on the quality of transmission acquired tomographic images
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Silvani, Maria Ines, Lopes, Ricardo T., de Almeida, Gevaldo L., Gonçalves, Marcelo José, and Furieri, Rosanne C.A.A.
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PARTICLES (Nuclear physics) , *NEUTRONS , *NUCLEAR reactors , *DETECTORS - Abstract
Abstract: The impact of the divergence of a thermal neutron beam and the scattered neutrons on the quality of tomographic images acquired by transmission have been evaluated by using a third generation tomographic system incorporating neutron collimators under several different arrangements. The system equipped with a gaseous position sensitive detector has been placed at the main channel outlet of the Argonauta Research Reactor in Instituto de Engenharia Nuclear (CNEN-Brazil) which furnishes a thermal neutron flux of 2.3×105 ncm−2 s−1. Experiments have then been conducted using test-objects with well-known inner structure and composition to assess the influence of the collimators arrangement on the quality of the acquired images. Both, beam divergence and scattering – expected to spoil the image quality – have been reduced by using properly positioned collimators between the neutron source and the object, and in the gap between the object and the detector, respectively. The shadow cast by this last collimator on the projections used to reconstruct the tomographic images has been eliminated by a proper software specifically written for this purpose. Improvement of the tomographic images has been observed, demonstrating the effectiveness of the proposed approach to improve their quality by using properly positioned collimators. [Copyright &y& Elsevier]
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- 2007
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6. EPR study of radiation stability of organic plastic scintillator for cardiovascular brachytherapy Sr90–Y90 beta dosimetry
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Alcón, Elmer P.Q., Lopes, Ricardo T., and de Almeida, Carlos E.V.
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DRUG dosage , *ELECTRON paramagnetic resonance , *ANGIOPLASTY , *MEDICAL research - Abstract
Abstract: Nowadays, more than one million percutaneous transluminal coronary angioplasties are being performed annually throughout the world. Restenosis is a significant problem associated with these angioplasty procedures. Radiation treatment with catheter-based β-emitter sources is currently under clinical trial to prevent this problem. Due to fast and worldwide introduction of β-sources for intravascular application, there is a growing interest in the dosimetry aspects. However, accurate dosimetry of β-radiation is more difficult than that of γ-radiation. Suitable detectors are not yet available with accuracy down to a tenth of a millimeter. Conventional measuring systems are not capable of such spatial resolution, except radiochromic film. However, film dosimeters have limited sensitivity and their radiation characteristics are different than those of tissue; therefore dose measurements require corrections. An alternative is to use water-equivalent plastic scintillators. In this work, organic plastic scintillator (BCF-10) dosimetry is studied using the Monte Carlo (MC) technique PENELOPE, and its radiation stability, after irradiation, is experimentally studied through electron paramagnetic resonance (EPR). Depth dose and dose profile are measured and compared to film dosimetry results. The EPR technique shows that the recovery time is dose independent in this kind of fiber and shows good stability. [Copyright &y& Elsevier]
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- 2005
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7. Conversion of a X-ray position sensitive detector for use in a thermal neutron tomographic system
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Silvani, Maria Ines, Lopes, Ricardo T., de Jesus, Edgar F.O., de Almeida, Gevaldo L., Braz, Delson, and Barbosa, Ademarlaudo F.
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DETECTORS , *X-rays , *THERMAL neutrons , *TOMOGRAPHY - Abstract
A gaseous position sensitive detector originally designed to operate with X-rays has been modified for using in thermal neutron tomographic systems. This modification included the replacing of the standard argon–methane mixture by 3He-enriched helium. Due to its low-density, helium should be submitted to a relatively high pressure in order to increase its stopping-power for the products emerging from the 3He(n,p)3H nuclear reaction. High pressure however, creates tightness problems. To mitigate this difficulty some heavy gases have been mixed to helium, reducing thus the range of the particles. In this work, three gases have been studied: pure 3He-enriched helium, and its mixture with argon–methane and with propane. For each case the parameters governing the performance of a detector coupled to a tomographic system, such as spatial resolution, linearity and response homogeneity have been determined. Besides that, the modulation transfer function and the distance resolution curve for a tomographic system incorporating a detector filled with those three different gases have been measured. The best spatial resolution – around 800 μm – has been obtained with a helium–propane mixture. This kind of detector is intended to equip thermal neutron tomographic systems, to perform non-destructive assay, exploiting thus the capability of this particle to pass through heavy materials where a X-ray tomography would not work properly. For an equivalent resolution, a tomographic system using a detector of this kind would require a much shorter acquiring time with regard to the first generation systems, since a sample translation is no longer necessary. [Copyright &y& Elsevier]
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- 2004
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8. 3D X-ray tomography to evaluate volumetric objects
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de Oliveira, Luís F., Lopes, Ricardo T., de Jesus, Edgar F.O., and Braz, Delson
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TOMOGRAPHY , *STEREOLOGY - Abstract
The 3D-CT and stereological techniques are used concomitantly. The quantitative stereology yields measurements that reflects areas, volumes, lengths, rates and frequencies of the test body. Two others quantification, connectivity and anisotropy, can be used as well to complete the analysis. In this paper, it is presented the application of 3D-CT and the stereological quantification to analyze a special kind of test body: ceramic filters which have an internal structure similar to cancellous bone. The stereology is adapted to work with the 3D nature of the tomographic data. It is presented too the results of connectivity and anisotropy. [Copyright &y& Elsevier]
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- 2003
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9. Fossil sea catfish (Siluriformes; Ariidae) otoliths and in-skull otoliths from the Neogene of the Western Central Atlantic.
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Aguilera, Orangel, Lopes, Ricardo T., Rodriguez, Felix, dos Santos, Thaís M., Rodrigues-Almeida, Caroline, Almeida, Paulo, Machado, Alessandra S., and Moretti, Tailan
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OTOLITHS , *OLIGOCENE Epoch , *NEOGENE Period , *CATFISHES , *SEDIMENTARY basins , *FOSSILS , *BONES ,BEETLE anatomy - Abstract
The examined Ariidae marine catfish from the Neogene of tropical America consisted of isolated skulls, otoliths and bone fragments, some of which were described independently as otolith-based species or skull-based species. We used three-dimensional digital rendering (microCT) of skull and otolith reconstructions to recognize anatomical patterns including skull-otolith morphology, spatial allocations of otoliths in the endocranium for taxonomic identifications. We recognized isolated Proto-Caribbean otoliths of Cathorops sp. from the late early Miocene to early Pliocene formations and isolated otoliths of † Aspistor verumquadriscutis , † Bagre urumacoensis and Notarius sp. from the late Miocene. We explored the endocrania of four fossil Ariidae skulls from the late Oligocene to late early Miocene Proto-Caribbean to determine their internal otolith-cranial morphology, and we identified and described the skulls of † Bagre protocaribbeanus and † Cantarius nolfi and erected the new species of † Bagre castilloensi n. sp. and † Bagre ornatus n. sp. based on the internal otolith-skull association. The first fossil record of Bagre marinus from the early Pliocene Cubagua Formation to the late Pliocene San Gregorio Formation completed the ariid geochronological sequence. We discuss the differential stages of fossil preservation of bioapatite skulls and aragonite otoliths according to the diagenetic processes as well as the paleoenvironmental conditions in the sedimentary basins. Detailed microCT, 3D reconstructions, X-rays, dry prepared skeletons and digital photos of otolith and skull are shown to elucidate the in-skull otoliths species descriptions. • The research provides the first descriptions of Neogene Ariidae catfish in-skull otolith and the erection of new species. • Neogene otoliths and in-skull otolith based species reinforce the paleodiversity of Ariidae. • MicroCT and 3D reconstructions elucidate the fossil in-skull otolith Ariidae species. [ABSTRACT FROM AUTHOR]
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- 2020
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10. Intracanal removal and apical extrusion of filling material after retreatment using rotary or reciprocating instruments: A new approach using human cadavers.
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Monteiro, Thamyres M., Cortes‐Cid, Victor O., Marceliano‐Alves, Marilia F. V., Campello, Andrea F., Bastos, Luan F., Lopes, Ricardo T., Siqueira, José F., and Alves, Flávio R. F.
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FILLER materials , *MEDICAL cadavers , *DENTAL pulp cavities , *X-ray computed microtomography , *HUMAN dissection - Abstract
Aim: This study compared intracanal removal of filling as well as the frequency and volume of extruded material after retreatment with either HyFlex or Reciproc instruments in mandibular teeth from cadavers. Methodology: The root canals of 14 pairs of contralateral single‐rooted teeth in mandibles of cadavers were instrumented with Reciproc R40 and filled using lateral compaction. The mandibles were scanned in a micro‐computed tomographic (micro‐CT) device before and after retreatment procedures. The contralateral teeth were assigned to two groups (n = 14) according to the retreatment protocol using either HyFlex or Reciproc instrument systems. In the HyFlex group, the HyFlex Remover instrument was worked 3 mm short of the working length (WL), followed by HyFlex CM 40.04 and 50.04 at the WL. In the Reciproc group, the R50 instrument was worked up at the coronal two thirds, followed by two more cycles until the WL was reached. Pre‐ and post‐operative micro‐CT images were analysed for extrusion and intracanal removal of filling material. Results: After retreatment, extrusion of filling material occurred in 11 (78%) and 14 (100%) teeth from HyFlex and Reciproc groups respectively (p >.05). A similar volume of extruded material was observed after retreatment with both systems (p >.05). A significant decrease in the intracanal filling volume was verified after retreatment with both tested systems (p <.05). However, residual filling material was found in all root canals, regardless of the system. The amount of filling material removed (HyFlex = 80.8%; Reciproc = 65.9%) and the operation time was similar between systems (p >.05). Conclusions: A high frequency of filling material extrusion was observed after retreatment with the two systems in a cadaver model, with no significant difference between them. Both protocols obtained similar efficacy in filling material removal procedures, although none completely cleaned the canals. [ABSTRACT FROM AUTHOR]
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- 2024
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11. Characterization of NORM‐type scales from the oil industry through spectrometry techniques and multivariate analysis.
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Izidório, Ana Carolina A. C., Santos, Ramon S., Gama Filho, Hamilton S., Anjos, Marcelino J., Leitão, Roberta G., Lopes, Ricardo T., and Oliveira, Davi F.
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PETROLEUM industry , *X-ray fluorescence , *MULTIVARIATE analysis , *SPECTROMETRY , *X-ray diffraction , *OCCUPATIONAL exposure , *ALKALINE earth metals - Abstract
The oil industries have as main problem in their activities of formation of scales containing material of the naturally occurring radioactive material (NORM) type on the internal walls of pipes and in some equipment that make up the process lines plant. This NORM can contribute to the exposure of workers during routine activities, either through external exposure, or internal, through inhalation or ingestion. Considering the concern with occupational exposure, environmental impacts and the plant's production capacity, resulting from the formation of the scales, this work characterized samples of scale by means of techniques of x‐ray fluorescence (XRF), x‐ray diffraction (XRD) and high‐resolution gamma spectrometry. The XRF showed concentrations of P, S, Cl, Ca, Mn, Fe, Sr, and Ba as the main elements of the sample; the XRD showed calcite and barite as predominant composition; in the gamma analysis, the concentrations of the activities varied from 104.6 to 1112.6 Bq kg−1 for 226Ra and from 16.4 to 385.2 Bq kg−1 for 228Ra, within the limits set by the International Atomic Energy Agency. The indices radium equivalent activity, absorbed dose rate and annual effective dose indices varied from 128.4 to 1665.9 Bq kg1; 58.4 to 748.0 nGy h−1 and 0.072 to 0.918 mSv y−1, respectively. Only the effective dose values were within the limits established by United Nations Scientific Committee on the Effects of Atomic Radiation, reinforcing the need for continuous monitoring on the platforms and the importance of keeping the radiological protection plan up to date, since the mobilization of NORM increases proportionally with the useful life of the production wells, thus increasing exposure indices. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Analysis of metals in particulate matter suspended in air by total reflection x‐ray fluorescence.
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Almeida, Ana Paula F., Santos, Ramon S., Ferreira, Gabriel C., Nardes, Raysa C., Sanches, Francis. A. C. R. A., Filho, Hamilton. S. Gama, Leitão, Roberta G., Anjos, Marcelino J., Lopes, Ricardo T., and Oliveira, Davi F.
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X-ray fluorescence , *X-ray reflection , *METAL analysis , *POLLUTION , *POISONS , *PARTICULATE matter , *AIR pollutants - Abstract
Atmospheric particulate matter (PM) is considered to be a set of pollutants suspended in the air, from industrial processes, motor vehicle exhaust, resuspended street dust, biomass burning, and others. Among the toxic chemical compounds, PM is considered contaminants of great importance for researchers, as they offer harmful effects to humans, fauna and flora. Moreover, exposure to PM can cause the development and/or worsening of diseases, mainly respiratory and cardiovascular. The aim of the present study was to evaluate the metals concentration in total suspended particulate matter in the air through total reflection x‐ray fluorescence technique (TXRF). The samples were collected from random points in five neighborhoods in the Metropolitan Region of the state of Rio de Janeiro/Brazil. TXRF measurements were performed using the benchtop TXRF spectrometer S2 PICOFOX. The results showed that the proposed methodology was able to detect the elements Cr, Fe, Ni, Cu, and Zn, in concentrations ranging from 2.0 to 200 ng.m−3. It can be concluded that the study methodology for determining the metal concentrations in air samples is an efficient and low‐cost solution for studying environmental pollution. [ABSTRACT FROM AUTHOR]
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- 2023
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13. Imaging techniques as tool in the characterization of the impact of silica nanofluid in Indiana limestone.
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de Araújo, Olga M. O., Sharma, Keerti V., dos Santos, Caio M. S. F. F., da Silva, Marcus V. S., dos Santos, Ramon S., Anjos, Marcelino J., Oliveira, Davi F., Machado, Alessandra S., and Lopes, Ricardo T.
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LIMESTONE , *CALCIUM carbonate , *CALCITE , *POROUS materials , *NANOFLUIDS , *X-ray fluorescence , *PETROLEUM - Abstract
Indiana limestone is composed mainly of calcite and aragonite minerals, which are different crystalline forms of calcium carbonate. Due to its composition of almost pure calcium carbonate (around 97%), it is widely used in the petroleum industry as a standard porous media for laboratory experiments with a huge scope in industrial applications. A method to improve oil recovery is associated with the use of nanoparticles (NP). One of the most promising is presented to be that of silica (Si) NP, because of their compatibility with the reservoir and subsurface abundance. In this work, we applied Si NP at a concentration of 0.5%, prepared in a base fluid of 1000 ppm in crude oil, injected in Indiana limestone and tested them with microtomography (microCT) and micro x‐ray fluorescence (microXRF) techniques to evaluate the impact of the treatment. Combining morphological results with the mapping of the elements, a more complete characterization of the sample is possible for a better understanding of these interactions applied in oil field industries. [ABSTRACT FROM AUTHOR]
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- 2023
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14. X‐ray computed microtomography time‐dependent analysis of sandwich bread in different storage conditions.
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de Lima, João Carlos R., de Araújo, Olga M. O., de Sá Silva, Aline S., Bastos, Luan F., Machado, Alessandra S., Oliveira, Davi F., and Lopes, Ricardo T.
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X-ray computed microtomography , *BREAD , *SANDWICHES , *IMAGE analysis - Abstract
Bread is one of the oldest foods of mankind, and among them, the sandwich bread is worldwide known and used. In this study we used the non‐destructive computed microtomography technique (microCT) to evaluate the behavior of bread structure over weeks after the production. In addition, the influence of the storage location of the sandwich bread, we performed a comparative analysis between storage at ambient temperature and refrigerated conditions. The analysis of the reconstructed images shows that the bread suffers loss of structure over the weeks. We also have found that keeping the bread refrigerated loses liquid, drying the bread, and thus increasing the loss of its structure. In addition, the porous structure of the bread was evaluated, and a complete characterization of the microstructural changes was performed over time. [ABSTRACT FROM AUTHOR]
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- 2023
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15. Analysis of the quality of industrialized coffee powder using the techniques of computed microtomography and x‐ray fluorescence.
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Machado, Alessandra S., de Sá Silva, Aline S., de Araújo, Olga Maria Oliveira, Santos, Ramon S., Leitão, Roberta G., dos Anjos, Marcelino J., de Oliveira, Davi F., and Lopes, Ricardo T.
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X-ray computed microtomography , *COFFEE grounds , *TRACE elements , *COFFEE , *POWDERS , *COPPER , *X-ray fluorescence - Abstract
The culture of coffee is very important in Brazilian scenery. Brazil is the world's largest coffee producer, responsible for 30% of the planet's production, and it is among the 15 largest coffee consuming nations. More and more, consumers look for better quality of coffee, and the presence of determinate composts would prejudice the health of the consumers. Therefore, this study suggests a method to identify and quantify commercially roasted ground coffee impurities/contaminants using computed microtomography (micro‐CT) and x‐ray fluorescence (XRF) techniques. A set of different commercially roasted ground coffees were investigated. The micro‐CT results showed that most of the coffee powder samples analyzed showed some contaminant, and in a specific brand, the amount of contaminants was higher than 9%. The 3D data provided information about the size and shape of these contaminants. The XRF results showed the macro elements P, S, Cl, K, and Ca and the micro elements Mn, Fe, Cu, Zn, Rb, and Sr. The elemental concentrations are in agreement with the values reported in the literature, except for the same specific brand, where the values found were much higher. The combined data of both techniques showed that the amount of impurities/contaminants in the ground coffee results in an increase of the macro and micro nutrients and also modifies the flavor and fragrance of the product, leading to an overall poor quality of the final beverage. [ABSTRACT FROM AUTHOR]
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- 2023
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16. Studies and Considerations on Forty-Three Gold and Silver Nose Ornaments from the Moche Tomb of the Lady of Cao.
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Gigante, Giovanni E., Cesareo, Roberto, Bustamante, Angel, Fernandez, Arabel, Franco, Régulo, Azeredo, Soraia, and Lopes, Ricardo T.
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SILVER-gold alloys , *SILVER alloys , *GOLD alloys , *DECORATION & ornament , *SILVER - Abstract
The authors studied forty-three beautiful nose ornaments from the Moche tomb of the Lady of Cao, located in the north of Peru, which has been dated to be around 300–400 d.C. Of these items, thirty-nine are composed of a sheet of gold alloy joined together in various manners to a silver alloy sheet, which provides a strong contrast at their interface. Two nose ornaments are on gold alloy and two on silver alloy. These nose ornaments were studied using the following methods: (i) Energy-dispersive X-ray fluorescence (EDXRF); (ii) Transmission of monoenergetic X-rays (XRT) and (iii) X-ray Radiography (RAD). The conclusion, deduced from all applied methods, was that two sheets of gold and silver alloys were joined together with various methods, including gluing, mechanically joining, soldering, smelting with the aid of heating or using mercury to create an amalgam. It cannot be excluded that a few areas, visibly appearing as silver, were obtained by depletion silvering from the base Au-Cu-Ag alloy. By analyzing a fragment from the silver area of a nose ornament and by studying a few other nose ornaments from the tomb of the Lady of Cao in situ, G. Ingo and co-workers concluded that a unique sheet of three-component alloy (Ag-Cu-Au), whichemployed and transformed the surface of the objects to appear to be gold and silver by depletion gilding and silvering. [ABSTRACT FROM AUTHOR]
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- 2023
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17. Wide cone beam CT dosimetry: Analysis of results and uncertainty evaluation.
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de Jesus, Fillipe M., Campos, Luciana T., Renha, Simone K., Dias, Priscila M.D.S., Pacífico, Leonardo D.C., Machado, Samara C.F., Sardenberg, Vitor M., Lopes, Ricardo T., and Magalhães, Luís A.G.
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CONE beam computed tomography , *HIGH voltages , *VOLTAGE - Abstract
To investigate the consistency of the recommended methodology, we analyzed the dosimetric results obtained for each setup beam shaping filter and tube voltage and evaluated the uncertainty associated with the full dose measurement process. A 300-mm PTIC was used to validate the results obtained with the 100-mm PTIC. Considering the other dosimetric parts, a cylindrical 160-mm diameter PMMA phantom and a cylindrical 320-mm diameter PMMA phantom were also used in the experimental protocol. For the lowest and highest tube voltages available, the CTDI air,160 values obtained by 1-step dosimetry with the 300-mm PTIC were greater than the respective values obtained by 2- and 3-step dosimetry with the 100-mm PTIC. This study established that careful positioning of the 100-mm PTIC in 2 or 3 steps, as well as proper execution of the other dosimetric parts recommended by the IAEA, represents a validated approach within up to 20% uncertainty for wide cone beam CT dosimetry. • Filters SS and S, and filters M, L and LL; result in equal CTDI air,160 values. • 1-step method using 300-mm PTIC prove feasibility of the experimental protocol. • Methodology recommended is a validated approach within up to 20% uncertainty. [ABSTRACT FROM AUTHOR]
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- 2024
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18. Caries-removal effectiveness of a papain-based chemo-mechanical agent: A quantitative micro-CT study.
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Lourenço, Roseane A., Neves, Aline A., Lopes, Ricardo T., Primo, Laura G., and Alves, Haimon D.
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DENTAL caries , *PAPAIN , *COMPUTED tomography , *DENTIN , *BONE density - Abstract
The aim of this study was to access the effectiveness and specificity of a papain-based chemo-mechanical caries-removal agent in providing minimum residual caries after cavity preparation. In order to do it, extracted carious molars were selected and scanned in a micro-CT before and after caries-removal procedures with the papain-based gel. Similar parameters for acquisition and reconstruction of the image stacks were used between the scans. After classification of the dentin substrate based on mineral density intervals and establishment of a carious tissue threshold, volumetric parameters related to effectiveness (mineral density of removed dentin volume and residual dentin tissue) and specificity (relation between carious dentin in removed volume and initial caries) of this caries-removal agent were obtained. In general, removed dentin volume was similar or higher than the initial carious volume, indicating that the method was able to effectively remove dentin tissue. Samples with an almost perfect accuracy in carious dentin removal also showed an increased removal of caries-affected tissue. On the contrary, less or no affected dentin was removed in samples where some carious tissue was left in residual dentin. Mineral density values in residual dentin were always higher or similar to the threshold for mineral density values in carious dentin. In conclusion, the papain-based gel was effective in removing carious dentin up to a conservative in vitro threshold. Lesion characteristics, such as activity and morphology of enamel lesion, may also influence caries-removal properties of the method. SCANNING 37:258-264, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]
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- 2015
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19. Evaluation of low voltage on electrical cables using microct and COMSOL Multiphysics.
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da Silva, Marcus V.S., de Araújo, Olga M.O., dos Santos, Caio M.S.F.F., de Oliveira, Davi F., Freitas, Cleiton M., and Lopes, Ricardo T.
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MAXWELL equations , *X-ray computed microtomography , *ELECTROMAGNETIC pulses , *FINITE element method , *ELECTROMAGNETIC fields - Abstract
Safety and quality are critical challenges in electrical engineering and unscheduled system outages caused by device failures present a significant concern. One of its main causes is the presence of air voids in the insulating layer of power cables. The main objective of this work was to evaluate the effect of current pulses, which generally occurs in transients, on the proliferation of voids in the insulating layer of electrical cables. X-ray microtomography (microCT) was used in the identification and analysis of air voids in aluminum (Al) and copper (Cu) electrical cables, with different cross-sectional areas, before and after electrical current pulses. The results showed an increase in voids caused by current pulses and an increase in electromagnetic fields and temperature inside the conductor. Furthermore, it was observed that the current pulses applied to the cables increased the agglomeration of small imperfections in voids of larger diameters and it was possible to verify the phenomenon of electrical arborescence in the cable with the aluminum core, as well as modifications in the core of stranded cables. Soon after, the Comsol Multiphysics software was used, which uses the Finite Element Method (FEM), solving Maxwell's equations, to better understand the information accessed by the microCT technique that describes electromagnetic phenomena in power cables. The results showed that cables with a greater number of voids have higher electromagnetic field densities when compared to cables without voids in the insulation, showing an increase of 7.5, 10.16, and 9.91 for the copper cables of 25, 35 and 50 mm2, respectively. • It was possible to verify that pulses of electrical currents generate air voids within copper and aluminum electrical cables. • With the microCT tool, it was possible to characterize the air voids in terms of location, volume and void size distribution. • The phenomenon of electrical arborescence can be investigated in the insulating layer of aluminum electrical cable. • Electromagnetic simulations demonstrated that air voids cause variations in dissipated power and thermal energy. [ABSTRACT FROM AUTHOR]
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- 2024
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20. Unprepared surface areas, accumulated hard tissue debris, and dentinal crack formation after preparation using reciprocating or rotary instruments: a study in human cadavers.
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Campello, Andrea F., Marceliano-Alves, Marília F., Siqueira Jr, José F., Fonseca, Simone C., Lopes, Ricardo T., and Alves, Flávio R. F.
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TOOTH fractures , *SURFACE area , *DEAD , *DENTAL pulp cavities , *HUMAN experimentation - Abstract
Objectives: This study using contralateral teeth from human cadavers assessed the amount of unprepared wall surface areas (USA), accumulated hard tissue debris (AHTD), and dentinal crack formation after root canal preparation using either reciprocating or rotary instruments. Materials and methods: Incisors with a single root canal from 11 human mandibles had their root canals prepared with Reciproc or Mtwo. Each contralateral tooth was treated with one of the test instruments in order to create matched pairs. Micro-CT scans were taken before and after preparation to instrument sizes 40 and 50 in both groups. USA and AHTD were evaluated in the full canal length or the apical portion only. Crack formation was also evaluated in the full root length. Results: After size 40, no significant differences in USA and AHTD were observed in the full canal length (P >.05). Separate analysis of the apical 4-mm canal revealed no difference in AHTD, but significantly more USA with Mtwo than Reciproc (P <.05). After size 50, the amount of USA was similar between groups both in the full canal and in the apical canal (P >.05). More AHTD were observed in the full canal after using Mtwo size 50 (P <.05), but no difference occurred in the apical canal only (P >.05). Intragroup analyses showed a significant decrease of USA and a significant increase of AHTD when preparation size increased from 40 to 50 (P <.05). In teeth without any pre-existing detectable dentinal defect (n = 38), crack formation occurred in 4 teeth, 2 from each preparation system. Clinical relevance: Reciproc instrument size 40 resulted in more prepared areas in the apical canal than Mtwo instrument of the same size. However, the amount of AHTD did not differ between them at this file size. Canal enlargement to size 50 prepared more walls but created more debris. Dentinal defects were produced after preparation with both systems. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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21. An ESR study on identification of gamma-irradiated kiwi, papaya and tomato using fruit pulp.
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Jesus, Edgar F. O., Rossi, Alexandre M., and Lopes, Ricardo T.
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GAMMA rays , *KIWIFRUIT , *PAPAYA , *TOMATOES , *ELECTRON paramagnetic resonance - Abstract
Summary In this work we use paramagnetic defects induced by radiation in the fruit pulp to identify gamma-irradiated kiwi, papaya and tomato. Pulp without seed, peels or stalks are treated by alcoholic extraction in order to remove water, soluble fractions and solid residue. The ESR spectra of pulp samples of irradiated fruit is composed of species A (g = 2.0045) and species C (g = 2.0201 and g = 1.9851), which are also observed in irradiated stalks and skins. In comparison with samples which are not submitted to alcoholic extraction, species C is stable enough to be used as a dose marker. Furthermore, the species C signal can be detected perfectly even in pulp samples irradiated with doses as low as 200 Gy. Irradiation doses of fruit, exposed to 200–900 Gy of a gamma rays, were estimated with an overall uncertainty of 15% using dried pulp samples. These results indicate that radicals induced in pulp have potential to be used in the identification and absorbed dose determination of irradiated fruit. [ABSTRACT FROM AUTHOR]
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- 1999
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22. Accuracy of Microcomputed Tomography in Detecting Dentinal Cracks: A Correlative Study with Scanning Electron and Operative Microscopy.
- Author
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Campello, Andrea F., Marceliano-Alves, Marília F., Provenzano, José C., Loyola, Simone C., Siqueira Jr., José F., Machado, André G., Machado, André L., Lopes, Ricardo T., Paiva, Maurício M., and Alves, Flávio R. F.
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TOOTH fractures , *SCANNING electron microscopy , *TRANSILLUMINATION , *TOMOGRAPHY , *DENTAL pulp cavities , *MICROSCOPY - Abstract
The aim of the study was to evaluate the accuracy of microcomputed tomography (mCT) to detect dentinal cracks when compared with scanning electron microscopy (SEM) and operating microscopy (OM). Different conditions of pixel size (10 or 17 μm), sample moisture (dry/moist), and transillumination (with/without) were evaluated. Additionally, the influence of the dentinal defect width on its detection was analyzed. The root canals of human mandibular incisors were prepared with the Reciproc R40 instrument (VDW, Munich, Germany). The roots were sectioned 5 and 10 mm from the apex, and mCT scans of middle and apical segments were performed at two pixel sizes: 10 μm and 17 μm, under dry and moist conditions (groups: 10dry, 10moist, 17dry, and 17moist). The operating microscope was used with and without transillumination (groups: OMTrans and OM). Findings showed that accuracy was moderate for the 10dry, 10moist, and OMTrans groups, poor for OM and very poor for 17dry and 17moist. The thickness of the dentin crack significantly influenced its detection by mCT using the resolution of 10 μm in both dry and wet conditions (P =.002), 17 μm in the dry condition (P =.002), and by the operating microscope using transillumination (P =.009). Some cracks visualized in SEM were not detected by mCT and an operating microscope. Not only the mCT resolution but also the sample moisture condition and the dentinal crack width can significantly influence its detection. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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23. Allometry, Function and Shape Diversification in the Inner Ear of Platyrrhine Primates.
- Author
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del Rio, Joaquin, Aristide, Leandro, dos Reis, Sergio F., dos Santos, Thais M. P., Lopes, Ricardo T., and Perez, S. Ivan
- Subjects
- *
NEW World monkeys , *BIODIVERSITY , *BIOMECHANICS , *ADAPTIVE radiation , *NATURAL selection - Abstract
The diversification of anatomical structures with functional importance during the branching process of a clade is a widely studied phenomenon in evolutionary biology. In recent years, there is a growing interest in the study of the inner ear, a structure associated with hearing, locomotion, and indirectly, with body size. These studies have been particularly important in primates. The platyrrhine radiation is an ideal system in which to study inner ear diversification because it is one of the major groups of living primates and an example of an adaptive radiation related to body size and ecological characteristics. In this work, we used micro-tomography, 3D geometric morphometrics, and phylogenetic comparative methods to explore the pattern of shape variation in the inner ear of platyrrhines and to assess whether this variation is related to size, locomotion, and vocalization. Our main results suggest that (1) diversification of inner ear morphology was achieved early in the radiation, particularly for the shape of the semicircular canals and the relative size of the cochlea; (2) inner ear shape diversification is generally not associated with changes in vocalization features or locomotion behaviors; and (3) conversely, body size is a strong predictor of inner ear shape. This last result contrasts with recent studies indicating that allometry has weak effects on platyrrhine cranial diversification and suggests complex factors driving inner ear diversification in the clade. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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24. Characterization and effect of nanocomplexed fluoride solutions on the inhibition of enamel demineralization created by a multispecies cariogenic biofilm model.
- Author
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Vieira, Thiago I., Alexandria, Adílis K., Menezes, Jaqueline C. V., do Amaral, Lilian H., dos Santos, Thaís M. P., Neves, Aline de A., Lopes, Ricardo T., Cabral, Lúcio M., Valença, Ana M. G., and Maia, Lucianne C.
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TOOTH demineralization , *CARIOGENIC agents , *X-ray powder diffraction , *DIFFERENTIAL scanning calorimetry , *FLUORIDES , *MELTING points - Abstract
Objectives: The aim of this study was to assess the in vitro caries preventive effect of nanocomplexed solutions of hydroxypropyl-β-cyclodextrin and γ-cyclodextrin associated with titanium tetrafluoride (TiF4) after different complexation times (12 or 72 h). Materials and methods: Enamel blocks were randomly distributed in 9 groups (n = 11): negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, TiF4, hydroxypropyl-β-cyclodextrin:TiF4 12 h, hydroxypropyl-β-cyclodextrin:TiF4 72 h, γ-cyclodextrin:TiF4 12 h, γ-cyclodextrin:TiF4 72 h, and NaF (positive control). The solutions were applied for 1 min and the blocks were exposed to a biofilm model. Nanocompounds were characterized by differential scanning calorimetry and X-ray powder diffraction. The percentage of surface microhardness loss (%SML), mineral density changes (ΔZ), lesion depth, surface morphology (scanning electron microscopy—SEM), and chemical characterization (energy-dispersive spectroscopy—EDS) were assessed. Results: No oxidation was observed, and the formation of the nanocomplexes was evidenced by changes in the melting point compared to pure cyclodextrins and the loss of crystallinity of the materials. Hydroxypropyl-β-cyclodextrin:TiF4 72 h resulted in lower %SML than negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, and TiF4 (p < 0.05). NaF differed from all groups (p < 0.05), except for hydroxypropyl-β-cyclodextrin:TiF4 72 h (p = 0.83). ΔZ of hydroxypropyl-β-cyclodextrin:TiF4 72 h was higher than negative control, hydroxypropyl-β-cyclodextrin, γ-cyclodextrin, γ-cyclodextrin:TiF4 1 2 h, γ-cyclodextrin:TiF4 72 h, and NaF (p < 0.05) and similar to TiF4 and hydroxypropyl-β-cyclodextrin:TiF4 12 h (p > 0.05). SEM/EDS detected Ti in the blocks subjected to TiF4-products. Conclusion: The hydroxypropyl-β-cyclodextrin:TiF4 72 h solution showed caries preventive effect on the surface and subsurface of the enamel. Clinical relevance: A hydroxypropyl-β-cyclodextrin nanosystem, in association with TiF4 after 72 h of complexation, may be a promising agent for the prevention of enamel demineralization. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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25. Uca maracoani (Crustacea, Decapoda, Ocypodidae) from a Miocene paleomangrove in Brazil: A case of evolutionary stasis among tropical American fiddler crabs.
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Lima, Daniel, Tavares, Marcos, Lopes, Ricardo T., Oliveira de Araújo, Olga M., and Aguilera, Orangel
- Subjects
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FIDDLER crabs , *SCYLLA (Crustacea) , *CRUSTACEA , *DECAPODA , *FOSSILS , *CRABS - Abstract
The Miocene fiddler crab Uca maracoani antiqua Brito, 1972, from the Pirabas Formation (Brazil), has been recurrently claimed to be a valid species and the oldest fossil record of the brachyuran crab family Ocypodidae. However, morphological investigations with the aid of microCT scan images of a large number of topotypic specimens and re-examination of the type material of U. maracoani antiqua revealed that it should actually be merged into the synonymy of Uca (Acanthoplax) maracoani (Latreille, 1802). Therefore, U. maracoani , the morphology and ecological traits of which have persisted essentially unchanged for at least 16 Ma (Burdigalian to present), is actually a long-lived crab species inhabiting an estuarine, sheltered mudflat environment that, likewise, has essentially remained unchanged. Burgeoning evidence suggests that evolutionary stasis may not be uncommon among mangrove crabs, as revealed by Afruca tangeri (Eydoux, 1835) from the middle Miocene in northeastern Spain and U. ornata (Smith, 1870) from the Plio-Pleistocene in Honduras. Uca antiqua is redescribed and illustrated based on 3D volume reconstruction and several topotypic specimens. The microCT analysis revealed a considerable number of fossil concretions of U. maracoani , with both males and females likely sharing the same burrow. This is the first fossil record of a male fiddler crab with a female inside a burrow, where mating usually takes place. This mating style is common to almost all extant American fiddler crabs. • This is the first complete and detailed taxonomic review of Uca maracoani antiqua. • Uca maracoani morphology persisted unchanged for at least 16 Ma. • Evolutionary stasis may be not uncommon among fiddler crabs. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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26. A cell-based dosimetry model for radium-223 dichloride therapy using bone micro-CT images and GATE simulations.
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Pinto, Gabriella M, Bonifacio, Daniel A B, de Sá, Lidia V, Lima, Luis Felipe C, Vieira, Igor F, and Lopes, Ricardo T
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MONTE Carlo method , *ABSORBED dose , *RADIATION dosimetry , *ALPHA rays , *CANCELLOUS bone , *IMAGE segmentation , *OPTICALLY stimulated luminescence , *RADIONUCLIDE imaging - Abstract
Dosimetry at the cellular level has outperformed macrodosimetry in terms of agreement with toxicity effects in clinical studies. This fact has encouraged dosimetry studies aiming to quantify the absorbed doses needed to reach radiotoxicity at the cellular level and to inform recommendations on the administration of radium-223. The aim of this work is to qualitatively and quantitatively evaluate the absorbed doses of radium-223 and the interactions of the doses at the cellular level. The analysis was performed by Monte Carlo simulations in GATE using micro-CT image of a mouse. Two physics lists available in the GATE code were tested. The influence of single and multiple scattering models on the absorbed dose distribution and number of particle hits was also studied. In addition, the fuzzy c-means clustering method was used for data segmentation. The segmentation method was suitable for these analyses, particularly given that it was unsupervised. There was no significant difference in the estimated absorbed dose between the two proposed physics lists. The absorbed dose values were not significantly influenced by scattering, although single scattering resulted in twice as many interactions as multiple scattering. The absorbed dose histogram at the voxel level shows heterogeneous absorbed dose values within each shell, but the observations from the graph of the medians were comparable to those in the literature. The interaction histogram indicates 104 events, although some voxels had no interactions with alpha particles. However, the voxels did not show absorbed doses capable of deterministic effects in the deepest part of the bone marrow. The absorbed dose distribution in images of mouse trabecular bone was compatible with simple geometric models, with absorbed doses capable of deterministic effects near the bone surface. The interaction distributions need to be correlated with in vivo studies for better interpretation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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27. The cost of living in Notosuchia (Crocodyliformes, Mesoeucrocodylia).
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Sena, Mariana Valéria de Araújo, Montefeltro, Felipe C., Marinho, Thiago S., Langer, Max C., Fachini, Thiago S., Pinheiro, André E. Piacentini, Machado, Alessandra S., Lopes, Ricardo T., Pellarin, Romain, Sayão, Juliana M., Oliveira, Gustavo R., and Cubo, Jorge
- Subjects
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COST of living , *OXYGEN consumption , *AEROBIC capacity , *CARDIOPULMONARY system , *CROCODILIANS , *BLOOD flow , *WARM-blooded animals - Abstract
Limbs of terrestrial notosuchian crocodyliforms are characterized by a permanent parasagittal position similar to that of mammals and dinosaurs. Thus, we expect high maximal rates of oxygen consumption (i.e., high aerobic capacities). To test this hypothesis, we inferred mass-independent maximal metabolic rates (MMRs) in seven notosuchian species using the femur blood flow rate (Q̇; cm3 s−1) correlated with the maximal metabolic rate as a proxy. We employed a phylogenetic eigenvector maps (PEMs) inference model based on 20 extant tetrapod species. Generally, ectothermic amniotes have lower maximal metabolic rates than similarly sized endotherms. However, certain anatomical features of the cardiorespiratory system in varanid lizards enable them to develop a more active lifestyle than other ectothermic sauropsids. We found that the retrodicted mass-independent aerobic capacity values for Notosuchia are significantly lower than those measured in mammals and varanid lizards sampled but significantly higher than those quantified in Crocodylia. Notosuchians exhibit Q̇ values on the femoral shaft higher than Crocodylus porosus , suggesting greater oxygen consumption during intense exercise, but significantly lower than those measured in varanid lizards. This condition probably allowed notosuchians to engage in prolonged strenuous locomotion activities, such as hunting prey, defending themselves from predators or avoiding competitors. The evolution of Mesoeucrocodylia metabolism involves at least two phenotypes, a relatively high (Notosuchia) and a low (Neosuchia, Crocodylia) MMR. We modeled three-dimensional (3D) objects from Notosuchia femora and conducted measurements on the nutrient foramina size. These values were used as a proxy to infer the blood flow rate (Q̇) and provided insights into the maximal metabolic rate in these terrestrial crocodyliforms. Our findings suggest that Notosuchia were likely ectotherms, but exhibited a more active lifestyle than extant Crocodylia. However, they had aerobic capacities significantly lower than those measured in varanid lizards. • Notosuchia were ectotherms with a high aerobic capacity compared to extant crocodylians. • They likely were more athletic crocodyliforms when compared to Crocodylus porosus. • The evolutionary history of Crocodyliformes shows a shift from a high to a low aerobic MMR reducing their energetic budget. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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28. Characterization of scale deposition in oil pipelines through X-Ray Microfluorescence and X-Ray microtomography.
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Oliveira, Davi F., Santos, Ramon S., Machado, Alessandra S., Silva, Aline S.S., Anjos, Marcelino J., and Lopes, Ricardo T.
- Subjects
- *
OIL field flooding , *X-ray computed microtomography , *PETROLEUM pipelines , *X-rays - Abstract
The formation of scales consists in one of the most relevant problems in the oil prospecting field and occurs when incompatible types of water (injected sea water and formation water) are mixed in the reservoir, unavoidably undergoing chemical interaction followed by mineral precipitation. In this work, scale samples extracted from obstructed oil pipes were characterized through X-Ray Microfluorescence and X-Ray microtomography by analyzing their elemental and structural composition. Different types of scale were found according to their elemental distribution (mainly BaSO 4 and CaCO 3) and to the way that they were deposited inside the pipes. The results of both techniques provided data that can be used to optimize the prevention and removal methods of such materials from pipes and equipments used in oil facilities. • Micro-XRF and microCT images of scale samples extracted from oil pipes were acquired. • The distribution and quantification of each element from samples of different piping material was obtained through micro-XRF. • The scale deposition behavior was evaluated by microCT and the fraction of pores and high density materials was quantified. • PCA analysis was performed in order to sort different types of scales. • The predominant type of scale for each piping application and material was determined. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
29. Monitoring bioturbation by a small marine polychaete using microcomputed tomography.
- Author
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Pennafirme, Simone, Machado, Alessandra S., Machado, Alessandra C., Lopes, Ricardo T., Lima, Inaya C.B., and Crapez, Mirian A.C.
- Abstract
• We generated volume-rendered 3D images of bioturbation by a small marine polychaete and monitored bioturbation through time. • We suggest several parameters to quantitatively monitor bioturbation. • μCT is a useful technique for quantitative monitoring of bioturbation by small marine polychaetes. Bioturbation is one of the principle biological processes involved in transporting particles and solutes within sediments, which contributes to the maintenance of biodiversity. In muddy polluted environments, bioturbation may increase pollutant flux at the water-sediment interface, thereby enhancing contaminant bioavailability. The behavior of organisms dictates bioturbation, and gallery shape influences the magnitude of solute transport. Thus, quantitative investigations of gallery shape are fundamental to understanding how pollutant and solute transport is enhanced by bioturbators in muddy sediments. However, there is a lack of tools for quantitatively analyzing gallery geometry, especially for assessing bioturbation and gallery properties through time. Despite the potential of microcomputed tomography (μCT) for quantitative analyses of bioturbation, few such studies have been carried out. Here, we aimed to investigate the potential of μCT for quantitatively assessing the shape and geometric properties of galleries made by small marine polychaetes and their evolution through time in muddy sediments. We focused on Laeonereis acuta (Treadwell, 1923) (Nereididae, Polychaeta), which is a key bioturbator in marine coastal ecosystems. Using 2D and 3D images generated from μCT, we evaluated L. acuta galleries and propose several indexes to quantitatively assess gallery evolution and the role of gallery parameters in bioturbation. Quantitative investigations of polychaete galleries using μCT can assist in monitoring how bioturbation influences sedimentary systems. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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30. Cranial and endocranial diversity in extant and fossil atelids (Platyrrhini: Atelidae): A geometric morphometric study.
- Author
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Aristide, Leandro, Strauss, André, Halenar‐Price, Lauren B., Gilissen, Emmanuel, Cruz, Francisco W., Cartelle, Castor, Rosenberger, Alfred L., Lopes, Ricardo T., Reis, Sergio F., and Perez, S. Ivan
- Subjects
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NEW World monkeys , *ATELIDAE , *MURIQUIS , *HOWLER monkeys , *WOOLLY monkeys - Abstract
Objectives: Platyrrhines constitute a diverse clade, with the modern Atelidae exhibiting the most variation in cranial and endocast morphology. The processes responsible for this diversification are not well understood. Here, we present a geometric morphometric study describing variation in cranial and endocranial shape of 14 species of Alouatta, Ateles, Brachyteles, and Lagothrix and two extinct taxa, Cartelles and Caipora. Methods: We examined cranial and endocranial shape variation among species using images reconstructed from CT scans and geometric morphometric techniques based on three‐dimensional landmarks and semilandmarks. Principal components analyses were used to explore variation, including the Procrustes shape coordinates, summing the logarithm of the Centroid Size, the common allometric component, and residual shape components. Results: Differences in endocranial shape are related to a relative increase or decrease in the volume of the neocortex region with respect to brainstem and cerebellum regions. The relative position of the brainstem varies from a posterior position in Alouatta to a more ventral position in Ateles. The shape of both the cranium and endocast of Caipora is within the observed variation of Brachyteles. Cartelles occupies the most differentiated position relative to the extant taxa, especially in regards to its endocranial shape. Conclusions: The pattern of variation in the extant species in endocranial shape is similar to the variation observed in previous cranial studies, with Alouatta as an outlier. The similarities between Caipora and Brachyteles were unexpected and intriguing given the frugivorous adaptations inferred from the fossil's dentition. Our study shows the importance of considering both extant and fossil species when studying diversification of complex traits. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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31. Crude oil analysis by X‐ray scattering technique.
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Oliveira, Davi F., Silva, Ana Cecília, Figueiredo, Willians P., Anjos, Marcelino J., and Lopes, Ricardo T.
- Subjects
- *
X-ray scattering , *PETROLEUM , *SILVER ions , *SILICON nanowires , *COMPTON scattering , *RAYLEIGH scattering , *LUBRICATING oils - Abstract
Composed of hydrocarbons and other substances, petroleum is classified as a nonrenewable source of energy. In its unrefined form, it is called crude oil. Currently, its derivates are widely used in domestic and industrial environments, with the greatest exponent being motor fuels and lubricating oils. Due to the overwhelming demand, new oil wells in the presalt region of Brazil are going to be drilled, which will, in its turn, increase the demand for analysis and require the use of less costly technologies. The purpose of this paper is to present an experimental method that aims at characterizing crude oil samples through their X‐ray scattering profiles without the need for any chemical preparation to be performed in advance, which will enable this method to be used for analyzing samples immediately after their extraction. For the experiment, a portable X‐ray scattering system composed by an X‐ray tube (silver anode) and a Si‐PIN detector was used in order to analyze samples from different wells. The process consisted in establishing a linear relationship between the effective atomic number and the ratio between peak intensities of Compton and Rayleigh scattering from known samples. The linear function, verified experimentally, was then applied to samples of crude oil, and the results showed that it is possible to characterize them on the basis of the Rayleigh to Compton scattering ratio. After the analysis, a multiple comparison test performed on the samples proved that this methodology indeed allows to differentiate samples of different origins and to verify the compatibility of samples extracted from the same well. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
32. Multiple factors behind early diversification of skull morphology in the continental radiation of New World monkeys*.
- Author
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Aristide, Leandro, Bastide, Paul, dos Reis, Sergio Furtado, Pires dos Santos, Thaís M., Lopes, Ricardo T., and Perez, S. Ivan
- Subjects
- *
SKULL morphology , *NEW World monkeys , *BIODIVERSITY , *MORPHOMETRICS , *MACROEVOLUTION - Abstract
Understanding the origin of diversity is a fundamental problem in evolutionary biology. The null expectation for the evolutionary diversification is that all changes in biological diversity are the result of random processes. Adaptive radiations depart from this expectation as ecological factors and natural selection are supposed to play a central role in driving exceptional diversification. However, it is not well understood how large‐scale continental radiations, given their characteristics, fit to these opposing theoretical models. Here, we used phylogenetic comparative methods and geometric morphometrics to study the evolutionary process of cranial diversification in the continental radiation of New World monkeys. Particularly, we tested several alternative evolutionary scenarios for morphological evolution in the clade. Results indicated that despite the platyrrhine radiation being old and geographically widespread, the formative patterns arising from the initial stages of diversification probably associated with an adaptive radiation can still be recognized today. We also show that no single explored factor (e.g., ecological or allometric) can be invoked as a complete explanation for the observed phenotypic diversity patterns in the clade and, moreover, that different cranial regions exhibit particular macroevolutionary patterns. Together, our results highlight the evident complexity behind large‐scale evolutionary radiations. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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33. Laser-induced alteration of microstructural and microscopic transport properties in porous materials: Experiment, modeling and analysis.
- Author
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Sharma, Keerti Vardhan, de Araujo, Olga M.O., Nicolini, João V., Straka, Robert, Ferraz, Helen C., Lopes, Ricardo T., and Tavares, Frederico Wanderley
- Subjects
- *
POROUS materials , *INDUSTRIAL applications , *LASER plasmas , *LIMESTONE , *POROSITY - Abstract
Porous materials are of great importance in various industrial applications. Microscopic modifications in the pore structures of these materials can change their functional behavior. We treat Indiana limestone by lasers to modify its pore structures microscopically. Microcomputed tomography (micro-CT) of the treated samples reveal that pulsed Nd:YAG laser with energy 330 mJ increases open porosity of limestone by 15% and almost doubles the total porosity. This laser increases the limestone pore connectivity by 460%. High power CO 2 laser increases the open porosity by 20% but it reduces the pore connectivity of limestone. Our findings show that pulsed laser beams induce high increase in porosity and connectivity. 3D pore scale modeling using Cascaded lattice Boltzmann method (CLBM) on a D 3 Q 27 model shows that regions treated by pulsed Nd:YAG lasers exhibit enhanced fluid transport efficiency compared to untreated regions. The obtained results successfully demonstrate that lasers can be used to induce a well controlled heat transfer in porous materials directly enhancing their morphometric characteristics and microscopic fluid transport behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
34. First Neogene Proto-Caribbean pufferfish: new evidence for Tetraodontidae radiation.
- Author
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Aguilera, Orangel, Rodriguez, Felix, Moretti, Tailan, Bello, Marianna, Lopes, Ricardo T., Machado, Alessandra S., Dos Santos, Thaís M., and Béarez, Philippe
- Subjects
- *
NEOGENE Period , *PUFFERS (Fish) , *ROCK analysis , *COMPUTED tomography , *PHYSIOLOGY - Abstract
This study reports a three-dimensional fossil skull of a Tetraodontidae that dates to the middle Miocene (Serravallian), which was recovered from a rock matrix from the Valiente Peninsula Formation in the Bocas del Toro Archipelago, Caribbean coast of Panama. The new species, † Lagocephalus striatus n. sp., is the first fossil species of Tetraodontidae described from the Proto-Caribbean/Central Western Atlantic. We used high-resolution micro-CT scans of fossil and extant species to identify morphological characters on the skull, including the neurocranium, oromandibular and opercular bones, hyoid arch, and pectoral girdle. Specimens of both extant and extinct species of similar size were compared for accurate identification. We assess the paleogeographic distribution of the pufferfish group in the Neogene of Tropical America after the complete formation of the Isthmus of Panama. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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35. Reassessment of the enigmatic crocodyliform "Goniopholis" paulistanus Roxo, 1936: Historical approach, systematic, and description by new materials.
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Piacentini Pinheiro, André E., Pereira, Paulo Victor Luiz Gomes da Costa, de Souza, Rafael G., Brum, Arthur S., Lopes, Ricardo T., Machado, Alessandra S., Bergqvist, Lílian P., and Simbras, Felipe M.
- Subjects
- *
VERTEBRATE phylogeny , *TAXONOMY , *SPECIES , *TEETH , *MUNICIPAL government - Abstract
The Crocodyliformes are the most represented vertebrate clade in the Upper Cretaceous sequences of the Bauru Group, Paraná Basin. However, some of the species described have an uncertain taxonomic status and phylogenetic position. For instance, “Goniopholis” paulistanus has been assigned as a nomem dubium, due to its description being based on scarce material. The “G”. paulistanus specimens (i.e. teeth and a left tibia) were discovered in two different localities in São Paulo state: Mirandópolis and Valparaíso municipalities; where the upper interval of the Adamantina Formation (Early Maastrichtian of Bauru Group) crops out. Revisiting these specimens, we observed multicrenulated teeth in middle dentary toot- row, a remarkable feature only shared with teleosaurids Machimosaurus hugii (Upper Jurassic of Laurasia) and M. rex (Lower Cretaceous of Tunisia). This apomorphy was also recognized in new material from the Alfredo Marcondes municipality (Presidente Prudente Formation), which are here also referred to “G”. paulistanus. We recognized the teeth of “G.” paulistanus as the lectotype, however the tibia cannot be assigned to a species as it was not collected in association with the teeth. We performed a phylogenetic analysis with a data matrix composed of 388 characters and 86 taxa, analyzed in TNT. The strict consensus tree recovered Neosuchia and Ziphosuchia (Notosuchia + Sebecia) within Mesoeucrocodylia. The species “G” paulistanus is valid, as a distinct and new genus within Sebecia, in a polytomy with Barreirosuchus, Pepesuchus, Itasuchus and Peirosaurus, forming the clade Itasuchidae. Stolokrosuchus is the sister taxon to Itasuchidae, the sister group of all other Sebecia (Peirosauridae (Mahajangasuchidae + Sebecidae and taxa affinis)). The clades Ziphosuchia, Sebecia and Itasuchidae are here redefined, and we find the last two clades to be more closely related to terrestrial notosuchids than to semiaquatic neosuchians. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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36. Utilization of nondestructive techniques for analysis of the Martian meteorite NWA 6963 and its implications for astrobiology.
- Author
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do Nascimento‐Dias, Bruno L., de Oliveira, Davi F., Machado, Alessandra S., Araújo, Olga M. O., Lopes, Ricardo T., and dos Anjos, Marcelino J.
- Subjects
- *
MARTIAN meteorites , *MARTIAN geology , *X-ray fluorescence , *CHEMICAL structure , *ASTROBIOLOGY - Abstract
Martian meteorites are excellent study materials for understanding the present and past of Mars, as they are important historical astrophysical artifacts because they possess information about Martian geological evolution and physical and chemical characteristics. In our case, we analyzed the NWA 6963 Martian meteorite classified as basaltic shergottite because of its chemical structure. A computerized microtomography (μCT) study in the NWA 6963 Martian meteorite provided us with 2D and 3D images that were extremely useful for ascertaining the internal structure of the analyzed sample and gave us the opportunity to find a crumpled material with a very peculiar structural format. In addition, it was possible to observe through the μCT that this encrusted material also has a completely different density of the meteorite. Calcium, strontium, and potassium were detected qualitatively, among others through the technique of X-ray fluorescence. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
37. New Records, Morphological Variation, and Description of the Skull of Liophis dorsocorallinus Esqueda, Natera, La Marca and Ilija-Fistar, 2005 (Serpentes: Dipsadidae).
- Author
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SOUTO, NATÁLIA M., PINNA, PEDRO H., MACHADO, ALESSANDRA S., and LOPES, RICARDO T.
- Subjects
- *
SNAKES , *SKULL , *COLUBRIDAE , *X-ray computed microtomography , *SCAPULA , *MAXILLA , *PENIS - Abstract
The article presents new records and detailed descriptions of Liophis dorsocorallinus, including its skull and hemipenis morphology. Topics discussed include meristic and morphometric variation, updates to the species' geographical distribution, and differences in ventral coloration observed in the specimens studied.
- Published
- 2017
38. Characterization an wooden Pietà sculpture from the XVIII century using XRF and microct techniques.
- Author
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Sanches, Francis Anna C.R.A., Nardes, Raysa C., Santos, Ramon S., Gama Filho, Hamilton S., Machado, Alessandra S., Leitão, Roberta G., Leitão, Catarine C.G., Calgam, Teresa E., Bueno, Regina, Assis, Joaquim T., Oliveira, Davi F., Lopes, Ricardo T., and Anjos, Marcelino J.
- Subjects
- *
WOOD sculpture , *X-ray computed microtomography , *X-ray spectroscopy , *BRONZE sculpture , *ZINC oxide , *BRONZE , *PRUSSIAN blue - Abstract
In this work the pigments, ground layer and the structure of a polychrome wooden Pietà sculpture from the 18th century was characterized using X-ray fluorescence and computed microtomography (microCT) techniques. It was possible to detect the elements: Ca, Ti, Fe, Cu, Zn, Ba, Au, Hg and Pb. It was possible to characterize the pigments Azurite, Prussian Blue, Green Earth, Vermilion, Lead white, Zinc white, and Gold foils. In the regions where there were restorations, it was possible to identify the presence of the lithopone pigment, indicating that these processes occurred from the 19th century. The microCT showed that the statue is a carved wood sculpture with a painting layer with high density pigments. Two different blocks of wood were identified joined together with a wooden pin. The statue was attached to its wooden base with different types of nails, showing that this step took place in a period of time later than the statue manufacturing. Details of the attaching of the eyes and damages due to insect galleries could be also found in this statue. • Cultural heritage objects analysis using X-ray fluorescence (XRF) and microCT) techniques. • Analysis of the internal structure of a wood sculpture using the microCT technique. • The microCT technique identified a base later added to the sculpture. • The XRF technique characterized of the pigments and the preparation layer. • The XRF technique allowed to characterize restoration areas. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
39. Analysis of clay smoking pipes from archeological sites in the region of the Guanabara Bay (Rio de Janeiro, Brazil) by FT-IR.
- Author
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Freitas, Renato P., Ribeiro, Iohanna M., Calza, Cristiane, Oliveira, Ana L., Silva, Mariane L., Felix, Valter S., Ferreira, Douglas S., Coelho, Felipe A., Gaspar, Maria D., Pimenta, André R., Medeiros, Elanio A., and Lopes, Ricardo T.
- Subjects
- *
CLAY , *ARCHAEOMETRY , *SMOKING , *FOURIER transform infrared spectroscopy techniques , *MULTIVARIATE analysis , *ANTIQUITIES , *EQUIPMENT & supplies - Abstract
In this study, twenty samples of clay smoking pipes excavated in an 18 km 2 area between the Macacu and Caceribu rivers, in the municipality of Itaboraí, Rio de Janeiro, Brazil were analyzed by FT-IR technique. The samples, excavated in different archeological sites of the region, are dated between the seventeenth and the nineteenth centuries and are part of the material culture left by Africans and African descendants that lived in the complex. FT-IR analyses and complementary SEM-EDS studies showed that the clay paste used in the manufacture of smoking pipes, mostly handcrafted, is composed of quartz, feldspar, phyllosilicates and iron oxides. Multivariate statistical tests (PCA) were applied to FT-IR data to assess the interactions between the archeological sites. The results indicated that one archeological site – Macacu IV – is greatly related to the other sites. The results obtained have helped archeologists and anthropologists in better understanding the manufacturing process employed in ancient ceramic artifacts produced during the period of colonial Brazil. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
40. Brain shape convergence in the adaptive radiation of New World monkeys.
- Author
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Aristide, Leandro, Reis, Sergio Furtado dos, Machado, Alessandra C., Lima, Inaya, Lopes, Ricardo T., and Perez, S. Ivan
- Subjects
- *
ANIMAL diversity , *SIZE of brain , *NEW World monkeys , *PRIMATES , *ADAPTIVE radiation , *COMPARATIVE method , *MORPHOMETRICS - Abstract
Primates constitute one of the most diverse mammalian clades, and a notable feature of their diversification is the evolution of brain morphology. However, the evolutionary processes and ecological factors behind these changes are largely unknown. In this work, we investigate brain shape diversification of New World monkeys during their adaptive radiation in relation to different ecological dimensions. Our results reveal that brain diversification in this clade can be explained by invoking a model of adaptive peak shifts to unique and shared optima, defined by a multidimensional ecological niche hypothesis. Particularly, we show that the evolution of convergent brain phenotypes may be related to ecological factors associated with group size (e.g., social complexity). Together, our results highlight the complexity of brain evolution and the ecological significance of brain shape changes during the evolutionary diversification of a primate clade. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
41. Analysis of a Brazilian baroque sculpture using Raman spectroscopy and FT-IR.
- Author
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Freitas, Renato P., Ribeiro, Iohanna M., Calza, Cristiane, Oliveira, Ana L., Felix, Valter S., Ferreira, Douglas S., Pimenta, André R., Pereira, Ronaldo V., Pereira, Marcelo O., and Lopes, Ricardo T.
- Subjects
- *
RAMAN spectroscopy , *18TH century sculpture , *SPECTROMETRY , *MOLECULAR spectroscopy , *MICROSCOPY - Abstract
In this study, samples were taken from the sculpture of Our Lady of Sorrows and analyzed by Raman spectroscopy and FT-IR. This sculpture has been dated to the early eighteenth century. Samples were also examined using optical microscopy and Energy Dispersive Spectroscopy (EDS). Based on chemical analysis, the pigments vermilion [HgS], massicot [PbO] and azurite [Cu 3 (CO 3 ) 2 (OH) 2 ] were found in the sculpture polychrome. The results indicate that the green polychrome of the sculpture's mantle comes from the blending of massicot and azurite. Because the literature reports that the mantle of the Our Lady of Sorrows sculpture is blue, the mixing of these pigments results from a production error. The results also indicate the presence of Au in the sculpture, which indicates the originality of the piece. The results from this study helped restorers to choose the appropriate procedures for intervening in the sculpture and contributed to the knowledge about the manufacturing process of Brazilian baroque sculptures. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
42. Multielement analysis in serum of healthy population of the metropolitan region of Rio de Janeiro in Brazil by SRTXRF.
- Author
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Canellas, Catarine G. L., Carvalho, Silvia M. F., Leitão, Roberta G., Bellido, Alfredo V. B., Anjos, Marcelino J., and Lopes, Ricardo T.
- Subjects
- *
BLOOD serum analysis , *HUMAN physiology , *METABOLISM , *PRINCIPAL components analysis , *BODY fluid analysis , *METROPOLITAN areas - Abstract
The determination of multielemental concentrations in physiological fluids is of considerable interest in clinical chemistry. Since it has been established these levels in human serum can be utilized as indicators for several pathological conditions. The multielement composition determination in human serum is important for the investigation of their role in human physiology and metabolism. From this research, more detailed studies on the health of individuals living in the metropolitan region of the state of Rio de Janeiro can be realized in order to improve the quality of life of these individuals. We studied 180 healthy volunteers (80 males and 100 females) aged 19 to 60 years. All the serum samples had been collected of people who live in the urban area of Rio de Janeiro City/Brazil. The measurements were performed at the X-Ray Fluorescence Beamline at the Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo. We were able to determine the concentrations of the following 11 elements: Na, P, S, Cl, K, Ca, Fe, Cu, Zn, Br and Rb. In this study, we used statistical analysis for the principal components. We were able to verify the presence of two factors that divided the elements into two groups: group 1 formed by elements: Cl, K, S and Ca and group 2 by elements Cu and Zn. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
43. Study of Response to Zinc in Human Prostate Spheroids Using X-Ray Microfluorescence.
- Author
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Leitao, Roberta, Santos, Carlos Antonio, Palumbo, Antonio, Souza, Pedro, Canellas, Catarine G. Leitao, Anjos, Marcelino J., Nasciutti, Luiz E., and Lopes, Ricardo T.
- Subjects
- *
PHYSIOLOGICAL effects of zinc , *PROSTATE diseases , *PROSTATE cancer , *CELL culture , *HYPERPLASIA - Abstract
Diseases of the prostate gland are the most frequently diagnosed in men after middle age. Spheroid cell culture is a useful technique for tissue engineering or regenerative medicine research, pharmacological and toxicological studies, and fundamental studies in cell biology. In this paper, we investigated zinc distribution in cell spheroids in benign prostate hyperplasia (BPH) and prostate cancer (PCa) (DU145) and analyzed the differences in the response to zinc (0–150 \mu \textM ) treatment using $\mu $ XRF with synchrotron radiation. The results showed nonuniform distribution of Zn in all the spheroids analyzed. The differential response to zinc of BPH and DU145 cell spheroids suggests that zinc may have an important role in PCa. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
44. The structure of two-layered objects reconstructed using EDXRF-analysis and internal X-ray ratios.
- Author
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Cesareo, Roberto, Buccolieri, Giovanni, Castellano, Alfredo, Lopes, Ricardo T., De Assis, Joaquim T., Ridolfi, Stefano, Brunetti, Antonio, and Bustamante, Angel
- Subjects
- *
X-ray fluorescence , *ELECTROMAGNETIC waves , *PARTICLE size determination , *IONIZING radiation , *CATHODE rays - Abstract
Many objects of common use (tools, utensils, metals, knick-knacks, dishes and glasses) and artifacts (for example paintings of all types) are composed of two or more layers. In many cases, it would be useful to determine the correct location, composition and thickness of the various layers. Non-destructive and non-invasive methods are described, based on energy-dispersive X-ray fluorescence which are able to 'reconstruct' the complete structure of a multilayered sample. These methods use, in different ways, the ratios of characteristic X-rays emitted by the elements of the layers, and, in particular, two effects can be usefully employed, effects which are based on the differential attenuation of Kα and Kβ or Lα and Lβ X-rays: Different self-attenuation of K or L X-rays emitted by an element characterizing a layer because of the different energy of the two K or L X-rays;, Different attenuation of the two K or L X-rays of an element characterizing a layer by a second superimposed layer., Furthermore, the ratio of the Kα (or Lα) X-rays emitted by an element characterizing the internal layer, to the Kα (or Lα) X-rays emitted by an element characterizing a second superimposed layer, can also be employed in the 'reconstruction' of the layers. In this paper, the theoretical background of all these methods is described, and typical examples are shown. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
45. Gamma transmission system for detection of scale in oil exploration pipelines.
- Author
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Oliveira, Davi F., Nascimento, Joseilson R., Marinho, Carla A., and Lopes, Ricardo T.
- Subjects
- *
GAMMA rays , *PETROLEUM prospecting , *PETROLEUM pipelines , *NUMERICAL calculations , *SCINTILLATION counters - Abstract
The goal of this study is to detect and quantify the thickness of the scale layer inside the service pipelines. For this purpose, a system composed of a 137 Cs source and a NaI(Tl) scintillation detector was developed. The source and the detector were positioned in geometry to make transmission measurements. A computational routine was developed to generate simulated data, which were later compared with the experimental ones, in order to calculate the thickness of scale layer. The results of the validation tests show similar values to the real ones. It was therefore possible to conclude that the procedure is efficient for the detection and quantification of materials inside pipelines, and that the system is advantageous for its application in the field, especially with respect to radioprotection. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
46. Encephalization and diversification of the cranial base in platyrrhine primates.
- Author
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Aristide, Leandro, dos Reis, Sergio F., Machado, Alessandra C., Lima, Inaya, Lopes, Ricardo T., and Perez, S. Ivan
- Subjects
- *
MAMMAL diversity , *SKULL base , *BRAIN physiology , *NEW World monkeys , *ANTHROPOLOGY , *PRIMATOLOGY , *ANIMAL morphology - Abstract
The cranial base, composed of the midline and lateral basicranium, is a structurally important region of the skull associated with several key traits, which has been extensively studied in anthropology and primatology. In particular, most studies have focused on the association between midline cranial base flexion and relative brain size, or encephalization. However, variation in lateral basicranial morphology has been studied less thoroughly. Platyrrhines are a group of primates that experienced a major evolutionary radiation accompanied by extensive morphological diversification in Central and South America over a large temporal scale. Previous studies have also suggested that they underwent several evolutionarily independent processes of encephalization. Given these characteristics, platyrrhines present an excellent opportunity to study, on a large phylogenetic scale, the morphological correlates of primate diversification in brain size. In this study we explore the pattern of variation in basicranial morphology and its relationship with phylogenetic branching and with encephalization in platyrrhines. We quantify variation in the 3D shape of the midline and lateral basicranium and endocranial volumes in a large sample of platyrrhine species, employing high-resolution CT-scans and geometric morphometric techniques. We investigate the relationship between basicranial shape and encephalization using phylogenetic regression methods and calculate a measure of phylogenetic signal in the datasets. The results showed that phylogenetic structure is the most important dimension for understanding platyrrhine cranial base diversification; only Aotus species do not show concordance with our molecular phylogeny. Encephalization was only correlated with midline basicranial flexion, and species that exhibit convergence in their relative brain size do not display convergence in lateral basicranial shape. The evolution of basicranial variation in primates is probably more complex than previously believed, and understanding it will require further studies exploring the complex interactions between encephalization, brain shape, cranial base morphology, and ecological dimensions acting along the species divergence process. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
47. Elemental concentrations in skin of patients with fibroeptelial polip using synchrotron radiation total reflection x-ray fluorescence.
- Author
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Soares, Júlio C. A. C. R., Anjos, Marcelino J., Canellas, Catarine G. L., and Lopes, Ricardo T.
- Subjects
- *
SKIN , *SYNCHROTRON radiation , *OPTICAL reflection , *X-ray spectroscopy , *TRACE elements in the body - Abstract
In this work, the concentrations of trace elements were measured in acrochordon, a skin lesion also known as skin tag or fibroepithelial polyp, as well as in normal skin from the same patient. The samples were analyzed by Synchrotron Radiation Total Reflection X-ray Fluorescence (SRTXRF) in the Synchrotron Light National Laboratory (LNLS) in Campinas/São Paulo-Brazil. The collection of lesion and healthy skin samples, including papillary dermis and epidermis, has involved 17 patients. It was evaluated the presence of P, S, Cl, K, Ca, Fe, Cu and Zn in the paired samples, which were compared, and significant differences were found in some of them. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
48. Spatial distribution of elements in the spheroids by prostate tumor cells using synchrotron radiation x-ray fluorescence.
- Author
-
Leitão, Roberta G., Santos, Carlos Antônio N., Junior, Antônio Palumbo, Souza, Pedro A. V. R., Canellas, Catarine G. L., Anjos, Marcelino J., Nasciutti, Luiz E., and Lopes, Ricardo T.
- Subjects
- *
SPHEROIDAL state , *X-ray spectroscopy , *SYNCHROTRON radiation , *TRACE elements in the body , *PROSTATE cancer - Abstract
The formation of three-dimensional cell microspheres such as spheroids has attracted attention as a useful culture technique. In this study, we investigated the trace elemental distribution (mapping) in spheroids derived from tissue prostate cancer (PCa). The measurements were performed in standard geometry of 45° incidence, exciting with a white beam and using an optical capillary with 20 μm diameter collimation in the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). The results showed that most elements analyzed presented non-uniform distribution. P, S and Cl showed similar elemental distribution in all the samples analyzed. K, Ca, Fe, and Cu showed different elemental distribution for the spheroids analyzed. Zinc presented more intense distributions in the spheroid central region for all spheroids analyzed. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
49. On the Performance of X-ray Imaging Plates in Gamma Radiography employing Reactor-produced Radioisotopes.
- Author
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Silvani, Maria Ines, de Almeida, Gevaldo L., Furieri, Rosanne C., and Lopes, Ricardo T.
- Subjects
- *
PERFORMANCE evaluation , *STRUCTURAL plates , *GAMMA rays , *RADIOGRAPHY , *IMAGE analysis , *NUCLEAR reactors , *RADIOISOTOPES , *CHEMICAL processes , *NUCLEAR counters - Abstract
Gamma-radiography employing radiographic films is a well established technique for non-destructive assays. The advent of X-ray sensitive Imaging Plates opens up new possibilities to apply this technique thanks to the advantages exhibited by this new device. Indeed, besides a sensitivity about 20 times higher then the conventional photographic film, requiring thus a shorter exposure time, it does not require a dark room for a cumbersome and time-consuming chemical processing associated to the development, an can be erased to be reused many times. Moreover, its development carried out by means of a laser beam produces digitalized images which can be promptly stored in a computer. Although its resolution is still poorer than that of the conventional film, those advantages overwhelms this specific parameter when it is not an essential feature for the intended application. This work evaluates the feasibility of employing X-ray Imaging Plates as detector for higher photon energies as those emitted by reactor-produced radioisotopes. Within this frame, radioisotopes such as 198Au and 56Mn, produced at the Argonauta research reactor in the Instituto de Engenharia Nuclear-CNEN have been employed as sources to acquire radiographic images of several pieces of equipment, devices and components. In order to keep the source appearance-with regard to the detector-as punctual as possible, reducing hence the penumbra effect, the mass of the irradiated material had to be limited. Therefore, due to the low neutron flux available at the main port of the reactor, the exposure times have to be extended along several hours or even a couple of days in order to reach an image with adequate contrast. This demand, nevertheless, does not constitute a serious hindrance as the exposure process can be carried out without any intervention or surveillance. Results have shown that in spite of the higher photon energies used, surpassing the X-ray range for which the imaging plates have been designed, it is feasible to use these devices for gamma-radiography. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
50. GEANT4 Tuning For pCT Development.
- Author
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Yevseyeva, Olga, de Assis, Joaquim T., Evseev, Ivan, Schelin, Hugo R., Paschuk, Sergei A., Milhoretto, Edney, Setti, João A. P., Díaz, Katherin S., Hormaza, Joel M., and Lopes, Ricardo T.
- Subjects
- *
PROTON beams , *TOMOGRAPHY , *PROTON-proton interactions , *ELECTROMAGNETIC waves , *SIMULATION methods & models , *NEUTRON absorbers , *NUCLEAR models - Abstract
Proton beams in medical applications deal with relatively thick targets like the human head or trunk. Thus, the fidelity of proton computed tomography (pCT) simulations as a tool for proton therapy planning depends in the general case on the accuracy of results obtained for the proton interaction with thick absorbers. GEANT4 simulations of proton energy spectra after passing thick absorbers do not agree well with existing experimental data, as showed previously. Moreover, the spectra simulated for the Bethe-Bloch domain showed an unexpected sensitivity to the choice of low-energy electromagnetic models during the code execution. These observations were done with the GEANT4 version 8.2 during our simulations for pCT. This work describes in more details the simulations of the proton passage through aluminum absorbers with varied thickness. The simulations were done by modifying only the geometry in the Hadrontherapy Example, and for all available choices of the Electromagnetic Physics Models. As the most probable reasons for these effects is some specific feature in the code, or some specific implicit parameters in the GEANT4 manual, we continued our study with version 9.2 of the code. Some improvements in comparison with our previous results were obtained. The simulations were performed considering further applications for pCT development. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
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