The journal Semina: Exact and Technological Sciences (e-ISSN 1679-0375) is a digital scientific journal, open access, with continuous flow, associated with the Office for Research and Graduate Studies (PROPPG) of the State University of Londrina (UEL). Original and review articles are published, focused on the FIELDS of Technology, including: Architecture and Urbanism, Computation, Chemistry, Engineerings , Geosciences, Mathematics, Physics and Statistics. The journal has free access and there are no fees for submission, review and publication of articles.
The Copyright Declaration for articles published in this journal is the author's right. Since manuscripts are published in an open access Journal, they are free to use, with their own attributions, in educational and non-commercial applications. The Journal has the right to make, in the original document, changes regarding linguistic norms, orthography, and grammar, with the purpose of ensuring the standard norms of the language and the credibility of the Journal. It will, however, respect the writing style of the authors. When necessary, conceptual changes, corrections, or suggestions will be forwarded to the authors. In such cases, the manuscript shall be subjected to a new evaluation after revision. Responsibility for the opinions expressed in the manuscripts lies entirely with the authors. This journal is licensed with a license Creative Commons Attribution-NonCommercial 4.0 International.
Evaluation of Artifacts Produced by a Commercial Portable XRF Device and their Influence on the Analysis of Artworks
This study investigates the origin and impact of spectral interferences associated with the Bruker Tracer III portable X-ray fluorescence (pXRF) spectrometer, used by the authors for elemental characterization of cultural heritage objects. Systematic analyses were conducted on reference materials and on the sculpture Head of Apollo from the Eva Klabin House Museum, Rio de Janeiro, facilitating the detection of instrumental peaks and improving the accuracy of qualitative analyses by minimizing instrument-derived interferences. Measurements were carried out under controlled conditions, both with and without the spectrometer’s radiation protection shield, using fixed operational parameters (40 kV, 35 μA and 60 s). The resulting spectra revealed peaks attributable to the instrument’s structural components. With the shield in place, elements such as Ca, Ti, Fe, Ni, Cu, Zn, and Pb were detected. In the absence of the shield, the peaks corresponding to Ca, Zn, and Pb were suppressed, although interferences from the remaining elements persisted.
Copyright (c) 2025 Roberta Manon de Paula Sales Borges, Josiane Emerich Cavalcante, Isis Verona Nascimento da Silva Franzi, Anderson Gomes de Paula, Evelyne Azevedo, Ricardo Tadeu Lopes, Davi Ferreira de Oliveira https://creativecommons.org/licenses/by-nc/4.0
Debret or Not? A Physicochemical Study of Prints from the Castro Maya Museum
This study presents a physico-chemical investigation of six watercolor prints attributed to Jean-Baptiste Debret, part of the collection held by the Castro Maya Museum in Rio de Janeiro, Brazil. The authenticity of several works in the museum’s Debret collection has been questioned, leading to the formation of a national commission that identified 40 out of 42 disputed pieces as forgeries. To contribute to the technical analysis of these works, this research applied non-invasive methods - macro X-ray fluorescence mapping (MA-XRF) and Fourier-transform infrared spectroscopy (FTIR) - to analyze pigments, binders, and paper fiber composition. Comparative multivariate statistical analyses were performed using principal component analysis (PCA) and component analysis robust (RPCA), aiming to identify chemical patterns distinguishing authentic works from those of unknown authorship. The results suggest significant differences between prints considered authentic and those of uncertain origin, particularly in the distribution and composition of binders and pigments. Similarities found in the use of Prussian blue pigment were not sufficient to establish authorship. This work demonstrates the value of scientific methods in art authentication and highlights the need for further interdisciplinary studies in museum collections.
Copyright (c) 2025 Valter de Souza Felix, André Rocha Pimenta, Yasmin da Rocha Fereira Felix, Rafaela Andrade Mesquita, Renato Pereira de Freitas https://creativecommons.org/licenses/by-nc/4.0
A Non-Destructive Characterization of a Crucifix by X-Ray Fluorescence and Digital Radiography
This study analyzes an 18th/19th-century crucifix from the sacristy of the Church of Santa Luzia, Rio de Janeiro, through X-Ray Fluorescence (XRF) and Digital Radiography (DR). The investigation aimed to identify the elemental composition of pigments and assess the structural condition of the sculpture. XRF revealed elements such as calcium, lead, and mercury, indicating historical pigments like calcium carbonate, lead white, and vermilion. The presence of lithopone and phthalocyanine materials introduced in the late 19th century suggests later repainting. DR imaging exposed structural issues including flaking, cracks, and hidden metallic components such as the halo, titulus crucis, and nails. Internal features like joints and fixations were also identified, enhancing understanding of fabrication and conservation needs. The results demonstrate the relevance of atomic techniques for cultural heritage preservation, providing essential data for conservation planning. The artwork belongs to the collection of IPHAN (Brazilian National Institute of Historic and Artistic Heritage).
Copyright (c) 2025 Anderson Gomes de Paula, Isis Verona Nascimento da Silva Franzi, Josiane Emerich Cavalcante, Roberta Manon de Paula Sales Borges, Rafael Azevedo Fontenelle Gomes , Fernando Cordeiro Barbosa Gonçalves , Marcos Vinicius Vieira Coutinho , Davi Ferreira de Oliveira , Ricardo Tadeu Lopes https://creativecommons.org/licenses/by-nc/4.0
Analysis of Oval Paintings Attributed to the Painter Leandro Joaquim Using XRF and MA-XRF
Three paintings attributed to the Brazilian artist Leandro Joaquim (1738–1798) were analyzed in situ using X-ray fluorescence (XRF) and macro X-ray fluorescence scanning (MA-XRF) techniques. The artworks belong to the collection of the Museu Histórico Nacional in Rio de Janeiro and depict landscapes of the city during the colonial period. Due to their compositional and aesthetic similarities, the paintings have been treated as a collection. The analyses revealed the presence of pigments such as lead white (2PbCO3 .Pb(OH)2, green earth (K(Al,Fe 3+), (Fe2+,Mg)O10 (OH)2), raw umber (Fe2O3 + MnO2), and vermilion (HgS) in all three paintings. It was also observed that all the artworks contain a lead-based ground layer. To further investigate the similarities among the paintings, the XRF data were submitted to Principal Component Analysis (PCA), which confirmed the similarity in their elemental composition. The results suggest that the paintings were created using compatible materials and techniques, reinforcing the hypothesis of a common authorship and production within the same historical and technical context.
Copyright (c) 2025 Ana Leticia Castro de Oliveira, Renato Pereira de Freitas, André Rocha Pimenta , Valter de Souza Felix, Monica Grôppo Parma, Isolda Maria de Castro Mendes, Marcelino José dos Anjos https://creativecommons.org/licenses/by-nc/4.0
In Situ Analysis of Greek Ceramics and Iberian Amphora by XRF at the Eva Klabin House Museum
The Eva Klabin House Museum (MCEK) in Rio de Janeiro houses ancient artifacts of significant cultural value. This study employed X-Ray fluorescence (XRF) to analyze four pieces: three Greek ceramics and an Iberian amphora. Analyses were conducted in situ with a portable Bruker Tracer III device (rhodium target, 40 kV, 35 µA, 60-second acquisition time). In the Iberian amphora, calcium (Ca), iron (Fe), and lead (Pb) were detected. The high Ca content suggests prolonged submersion encrustations, while the predominant Fe indicates iron-rich clay. Among the Greek ceramics, the situla contained Ca, Fe, and cobalt (Co), with Co raising concerns about potential later pictorial interventions or forgery. The Archaic Greek vase and the smaller vase showed similar compositions, dominated by Fe and Ca, suggesting the use of iron oxide pigments and possible calcite or gypsum in the clay. Trace elements such as manganese, zinc, and strontium provided additional insights into clay origin and production techniques. The results highlight the need for complementary analytical methods. These methods would help determine clay sources, pigments, and manufacturing processes more precisely, while underscoring the importance of non-destructive analysis for preserving museum collections.
Copyright (c) 2025 Josiane Cavalcante, Roberta Manon de Paula Sales Borges, Isis Verona Nascimento da Silva Franzi, Anderson Gomes de Paula, Evelyne Azevedo, Ricardo Tadeu Lopes, Davi Ferreira de Oliveira https://creativecommons.org/licenses/by-nc/4.0
Lead Isotope Ratios in Archaeological Provenance: LA-ICP-MS Comparative Analysis
The correlation between an element and its original source (geogenic or anthropogenic) can be studied through the isotopic composition of lead (Pb), which remains unchanged by physical or chemical processes. This study used laser ablation coupled with inductively coupled plasma mass spectrometry (LA-ICP-MS) to identify concentrations of lead isotopes 208Pb, 207Pb, 206Pb and 204Pb in three coins attributed to the Roman Empire. The objective was to identify the geographical origin of the raw materials utilized or that contaminated these artifacts. Pb isotope ratios were analyzed using Neptune and Element 2 instruments from Thermo™ and compared with the Oxford Archaeological Lead Isotope Database (OXALID). The calibration of the Neptune commenced with the NIST 610 standard, followed by 45 blank readings and subsequent sample readings. For the Element 2, 20 points per sample were selected, with measurement times of 25 seconds for the blank and 36 seconds for data acquisition, including the NIST 610 standard. The results show that the samples have residual lead isotopic ratios compatible with the OXALID database for the Roman Empire region, indicating possible authenticity. Both instruments showed good agreement, with the Element 2 model offering advantages in statistical analysis and lower sensitivity to sample contamination.
Copyright (c) 2025 William Murussi Canto, Armando Dias Tavares Junior, Mauro Cesar Geraldes, Catarine Canellas Gondim Leitão, Marco Helênio de Paula Alves Coelho https://creativecommons.org/licenses/by-nc/4.0
Archaeometric Analysis of Potentially Damaging Material to the Collection of Museu de Ciências Naturais Carlos Ritter
Museological documentation is an indispensable activity in the daily operations of a museum. Its purpose is closely linked to the role of the institution as a “place of research.” However, the conservation state of a collection is directly affected by the processes the museum undergoes, which is related to the concept of Preventive Conservation. Yet, these activities are not always properly documented. This study demonstrates the importance of documentation for the preservation of a museological collection based on a case at Museu de Ciências Naturais Carlos Ritter, Riogrande do Sul, Brazil. In this case, archaeometric analyses were necessary to characterize a material in contact with the taxidermized specimens of the collection. The application of this material has not been properly documented and could have posed risks to both the collection and the staff. Using EDXRF, XRD and FTIR, the material was characterized as a mixture of aluminum oxide and graphite, two solid substances that are non-reactive and non-toxic to humans. Nevertheless, the museum deemed the material a distraction for visitors and decided to remove the powder from the display cases.
Copyright (c) 2025 Lucas de Souza Lima Pereira, Lisiane Pereira, Bruno da Silveira Noremberg, Mateus Meneghetti Ferrer https://creativecommons.org/licenses/by-nc/4.0
Study of Portuguese Coins Issued During the Reign of D. João with pXRF Technique and Multivariate Analysis
Portable energy dispersive X-Ray Fluorescence (pXRF) technique was applied for the study of 113 Portuguese coins minted during the reign of D. João I (1385-1433). Multivariate analysis was also employed to obtain more information about the coin set. These coins are part of a collection that belongs to the National History Museum in Rio de Janeiro (MHN). Different Portuguese currencies were studied such as Real Branco, Real de 10 Soldos, and ½ Real Cruzado. The coins were minted with an alloy known as billon, which is made of copper and silver. The reigns of D. João I (1385-1433) and his predecessor, D. Fernando (1367-1383), had intense warlike activity. This activity affected the economy, mainly during the reign of D. João I where the legal content of silver in coins was lower (2.78% weight) in contrast, for instance, with the reign of D. Fernando (8.33% weight). It was verified that some coins have a concentration below the legal value, while an expressive number of coins did not present silver in their composition. A Principal Component Analysis (PCA) was able to separate one monetary value coin regarding the city that it was minted.
Copyright (c) 2025 Guilherme Augusto Lisboa Nogueira, Paulo Sérgio Parreira, Rosa Bernstein Scorzelli, Carlos Roberto Appoloni https://creativecommons.org/licenses/by-nc/4.0
Use of the MA-XRF Technique in the Authentication of Guignard's Artwork Recovered by the RJ Civil Police
Artworks are frequently implicated in the commission of crimes of money laundering, fraud, corruption and robbery/theft. On August 10, 2022, Operação Sol Poente (Operation Setting Sun), launched by the Civil Police of Rio de Janeiro, recovered seventeen artworks stolen from the Boghici Collection. Among them was the Menino [Boy] (1935), by Guignard. For this reason, forensic examinations were conducted to verify the authenticity of the recovered artworks. Therefore, macro X-ray fluorescence scanning (MA-XRF) was employed as a portable and non-invasive technique to obtain elemental maps of the chemical composition present in the paint layers. The objective of this study was to demonstrate the potential of the MA-XRF technique in the context of a high-profile criminal investigation. Elemental mapping was conducted using the portable MA-XRF system, model CRONO (Bruker), on both the authenticated and unauthenticated artworks. The resulting elemental distributions exhibited significant similarities, indicating consistency in the materials and techniques used in their production. These results indicate similarities in the creation process and materials of the paintings. Although the authentication of artworks remains a complex and multidisciplinary process, the results of this study underscore the value of MA-XRF as a forensic tool capable of providing valuable insights in the resolution of forensic cases.
Copyright (c) 2025 Nilton Thaumaturgo Rocha Junior, Claudia Regina Ferreira de Souza, André Rocha Pimenta, Valter de Souza Félix, Renato Pereira de Freitas https://creativecommons.org/licenses/by-nc/4.0
Portable NIR Applied to the Evaluation of Resin, Glue and Agglutinant used in Canvas Paintings
The aim of this work was to study various compounds commonly used in painting canvases by employing portable near-infrared spectroscopy (portable NIR) and to discriminate the compounds through exploratory statistical analysis of the spectra data. To this end, a painting specifically created for archaeometric analysis was examined. Two portable spectrometers with complementary wavelength ranges were combined for the measurements, one operating from 900 to 1700 nm (11100 - 5880 cm-1) and the other from 1350 to 2150 nm (7400 - 4650 cm-1). Portable NIR spectrometry identified characteristic spectral bands for each class of compound: waxes, binders, organic resins, and acrylic resins. Applying exploratory statistics via principal component analysis (PCA) allowed for material differentiation. This study demonstrated that combining NIR spectroscopy and PCA is a versatile tool for achieving consistent results in this application.
Copyright (c) 2025 Fábio Luiz Melquiades, Rafael Molari, Carlos Roberto Appoloni https://creativecommons.org/licenses/by-nc/4.0
A Hybrid Model for Cellular Dynamics in Colorectal Crypts
Colorectal cancer is believed to originate from abnormal cell proliferation in small cavities of its epithelium called crypts. We present a hybrid framework that couples a Voronoi tessellation-based cell model with a continuous differential model to describe cellular dynamics, proliferation, and differentiation in a colorectal crypt. The framework is implemented numerically using finite difference and finite element methods. This~allows us to simulate how cells move, proliferate, and differentiate in normal and abnormal scenarios. We consider in particular the normal homeostatic case for validating the framework, and simulate two abnormal scenarios where perturbations in cell distribution or proliferation are imposed. The benefit of such a hybrid model is that we can freely impose perturbations and show results for cellular dynamics, proliferation, and differentiation at two different scales: a macro continuous scale and a micro cell scale. This framework provides insights into how cell behavior changes under abnormal conditions and how crypt lesions and adenomas may originate from cellular dynamics perturbations.
Copyright (c) 2025 Ítalo José Lima de Sousa, Giuseppe Romanazzi https://creativecommons.org/licenses/by-nc/4.0
Curve fitting and autoregressive models in admissions data for respiratory diseases
This study investigated hospitalization costs for respiratory diseases in the state of São Paulo between 2002 and 2025, analyzing the dynamics of these expenses within the Brazilian Unified Health System (SUS) and contextualizing the challenges of financing and managing public health in Brazil. The objective of this work was to identify historical patterns and understand expenditures by analyzing data from the DATASUS Hospital Information System. Using polynomial, logistic, and trigonometric curve fitting, as well as statistical time series models, with emphasis on the seasonal ARIMA model, seasonal trends and patterns in hospital expenditures were identified. This allowed for the capture of seasonal behaviors related to the amounts paid, specifically regarding the increase in hospitalizations for respiratory diseases during the transition between fall and winter. Finally, in the graphs associated with fluctuations around the average trend, two level transitions were observed in relation to the values paid: one associated with COVID-19 (mid-2020) and the other associated with H1N1 (in 2009). These levels correspond to the values of K=22.65 million, referring to the pre-COVID logistics model, and to K=35 million (logistics model that includes the COVID-19 pandemic period).
Copyright (c) 2025 Raphael de Oliveira Garcia, Graciele Paraguaia Silveira, Bruna Santos Silva https://creativecommons.org/licenses/by-nc/4.0
Interpolation Features in ContExt Software for Mammography Processing
This study proposes the expansion of the functionalities of the ContExt software, designed for contour extraction and mesh generation for numerical simulations in medical imaging. The main innovation is the incorporation of interpolation methods to enlarge contours after image resolution reduction, thereby enabling greater computational efficiency. Bilinear, bicubic, biquadratic, and cubic spline methods were evaluated, along with refinement techniques such as node removal and the Ramer–Douglas–Peucker algorithm. Reducing the image to half of its original resolution resulted in a significant decrease in processing time (over 95%) while maintaining satisfactory contour quality. However, a reduction to one-quarter resolution compromised the fidelity of the extracted structures. Bilinear method achieved the highest overlap rate, whereas the cubic spline proved to be the most accurate. Tests demonstrate that the new functionalities integrated into ContExt make the software more versatile and efficient for processing high-resolution images, with potential applications in various clinical and computational contexts.
Copyright (c) 2025 Rafael Tokairin, Rafael Furlanetto Casamaximo, Neyva Maria Lopes Romeiro, Pedro Zaffalon da Silva, Eliandro Rodrigues Cirilo https://creativecommons.org/licenses/by-nc/4.0
Local Controllability Analysis for a Tumor Dynamics Model
This study investigates the local controllability of a mathematical model describing tumor dynamics, incorporating cellular competition and external interventions represented by a control variable. The model analyzed is a modified version of the formulation proposed by Gatenby (1996), and its dynamics are explored through linearization around equilibrium points. Using the Kalman rank condition, we establish the circumstances under which the system exhibits local controllability. The results provide a theoretical foundation for understanding how external stimuli can steer the system between distinct biological states, particularly in the context of interactions between healthy and tumor cells. The work bridges concepts from control theory and mathematical oncology, aiming to support the development of more effective clinical intervention strategies. Our analysis offers insights into identifying scenarios in which treatment, modeled as an external control input, can effectively stabilize or even reverse tumor growth.
Copyright (c) 2025 Francis Felix Cordova Puma https://creativecommons.org/licenses/by-nc/4.0
Review of Mean-Field Theory for the Robotic Swarms Common Target Problem
This review provides a literature overview of the usage of Mean-Field Theory (MFT) for modelling the performance estimation of algorithms solving the common target problem in robotic swarm navigation. This problem involves coordinating multiple robots to converge simultaneously towards a single target, which can result in congestion and degraded performance. Its main objective is to minimise the maximum time required for all robots to reach and then depart from the target. The challenge lies in ensuring effective coordination among the robots to prevent conflicts and optimise resource utilisation. MFT may accurately predict navigation metrics, such as agent arrival and departure times, target location density, and system throughput under congestion, and it may enable control strategies based on distributed feedback. This literature overview illustrates that MFT is an effective and promising mathematical tool to mitigate the issues of high dimensionality and complexity of interactions present in systems consisting of a large number of agents.
Copyright (c) 2025 Yuri Tavares dos Passos, João Victor Neves de Souza Nunes https://creativecommons.org/licenses/by-nc/4.0
Analysis of Local Stability for Discrete Lotka-Volterra Models
This paper applies the stability theory of discrete systems to a predator–prey model with a specific structure, formulated directly in discrete time. This approach offers didactic and computational advantages for modeling ecological systems with non-overlapping generations, contrasting with methods that discretize continuous models. This direct formulation captures the inherently discrete nature of ecological monitoring and non-overlapping generations, while presenting particular analytical challenges. Through linearization and spectral analysis, we obtain explicit stability conditions for the system's three equilibria: total extinction, which is always unstable; predator exclusion; and coexistence, whose local behaviors depend on conditions among biotic parameters. The results provide practical criteria for predicting population persistence, offering a foundation for applied studies in control and conservation.
Copyright (c) 2025 Francis Félix Cordova Puma, Mireya Mendiguren Mager https://creativecommons.org/licenses/by-nc/4.0
Quantile nonlinear regression for modeling maize growth data
Statistical modeling is fundamental in plant growth studies as it guides management practices across different developmental stages. Among existing approaches, nonlinear regression models stand out for describing growth patterns over time through estimated parameters, typically obtained via least squares methods. However, this approach is limited to average data analysis and remains sensitive to outliers and variance heterogeneity. Quantile regression emerges as a robust alternative, enabling estimation across different quantiles without requiring normality assumptions for errors. This study aimed to analyze corn plant growth over time using quantile nonlinear regression and to investigate critical points in the applied models. We evaluated logistic, Gompertz, and Chanter models, assessing their goodness-of-fit through the Akaike Information Criterion (AIC), intrinsic nonlinearity measures, and two novel statistics proposed here: quantile correlation and the weighted sum of squared deviations (WSSD). Results demonstrated that the Chanter model provided the best fit for the analyzed dataset, with strong performance across different quantiles.
Copyright (c) 2025 Pollyane Vieira da Silva, Taciana Villela Savian https://creativecommons.org/licenses/by-nc/4.0
Population Growth Models Using Fuzzy Ordinary Differential Equation
Fuzzy mathematics is a branch of mathematics that presents a new approach to the classical notion of set, enabling the generalization of concepts and results from classical mathematics. Using the concept of fuzzy number, a generalization of the real number, we study fuzzy ordinary differential equations, generating ampler solutions to differential equations that model population growth. In particular, we examined a model for the growth of microorganisms in milk. By applying the fuzzy solution we expanded the possible parameter values of the models and studied their relationships. In this context, we study the properties of interactive fuzzy numbers, as well as their applications in mathematical modeling. Through concrete examples, we illustrate the application of fuzzy mathematics and interactive fuzzy numbers in real-world situations, highlighting their relevance in decision-making in contexts of uncertainty and imprecision. Leveraging the solutions and parameters values reported in the literature, the theory of interactive fuzzy numbers was used to develop predictive models. These models encompass intervals centered around the values deterministically predicted values, incorporating deviations within the confidence interval obtained for one of the parameters in each model.
Copyright (c) 2025 Diogo Sampaio da Silva, Roberto Antonio Cordeiro Prata https://creativecommons.org/licenses/by-nc/4.0
Numerical Simulations of High-lift Configurations on a NACA4412 Airfoil
This study examines the performance of different high-lift device configurations applied to a NACA 4412 airfoil, highlighting their respective advantages and disadvantages. Numerical simulations were performed using the open-source CFD code OpenFOAM® for five distinct configurations—plain flap, split flap, slotted flap, Fowler flap, and Junkers flap—under equivalent conditions, enabling a consistent comparison of results. All flaps were deflected by 10° and analyzed at a Reynolds number of 1.7 × 10⁵ over an angle-of-attack range from −4° to 16°. The Spalart–Allmaras turbulence model was adopted in all steady-state simulations. Quantitative analyses were conducted for the lift (Cl) and drag (Cd) coefficients per unit length, as well as for the pressure coefficient (Cp) on the airfoil surfaces, in addition to the velocity and pressure flow fields. The results demonstrated reliable and consistent predictions of lift and drag generation; however, convergence difficulties were observed at angles of attack near stall conditions. Furthermore, the simulations revealed superior lift performance for flap configurations commonly employed in the aeronautical industry, particularly the slotted flap and the Fowler flap.
Copyright (c) 2025 Odenir de Almeida, Thiago Rezende de Castro https://creativecommons.org/licenses/by-nc/4.0
Numerical Study of the Influence of Blood Viscosity on Aortic Blood Flow with Left Ventricular Assistance Support Pump
Heart failure (HF) is a condition responsible for thousands of deaths each year. It is characterized by the heart's inability to effectively supply blood to the systemic circulation. In such cases, the implantation of a pump known as a left ventricular assist device (LVAD) helps a failing heart restore proper blood flow. However, LVAD implantation may lead to complications such as an increased risk of stroke, thrombus formation, and reverse flow through the aortic valve. This study aims to numerically investigate a section of the aorta coupled to a LVAD pump, using computational fluid dynamics. The objective is to identify how increased LVAD pump speed and blood viscosity impact hemodynamic variables, which may contribute to the adverse effects of mechanical support. Real data from a patient with an implanted LVAD support were analysed using six viscosity models and five different LVAD pump flow rates. Several simulations were conducted to compare the hemodynamic variables' results across different viscosity models. Subsequently, the results for the various LVAD pump flow rates were analyzed. These analyses allowed the identification of critical points within the geometry, associated with the adverse effects of each hemodynamic variable.
Copyright (c) 2025 Aurélio Ferreira da Costa, Alexandre Marconi de Souza da Costa https://creativecommons.org/licenses/by-nc/4.0
Health Risk of Particulate Matter in Canoas and Paulínia for the Population Aged 30 to 59 Years
Particulate matter, such as PM10, poses a threat to health and the environment. This study assessed the health impacts associated with the average annual PM concentrations in Canoas, Rio Grande do Sul, and Paulínia, São Paulo, from 2010 to 2019, comparing them to World Health Organization (WHO) guidelines. Air pollution is a global concern due to its {association} with respiratory diseases. Computational tools such as AirQ+ and Openair (R programming language) are essential for linking health and pollution data. The analyses showed a decrease in PM10 concentrations over time according to the Theil-Sen test. In Canoas, a significant reduction (p-value < 0.01) of 2.18 µg. m-3 per year was observed, while in Paulínia a reduction of 0.35 µg. m-3 per year was not significant (p-value > 0.10) and still remained above the 15 µg. m-3 recommended by the WHO. The relative risk calculation estimated that with this reduction, 4,367 and 2,351 health events could have been avoided in Canoas and Paulínia, respectively. These data highlight the need for policies to improve air quality and protect public health.
Copyright (c) 2025 Bianca Cristina dos Reis Pinto, Julia Marly Pinheiro Americo, Danilo Covaes Nogarotto, Daniela Montanari Migliavacca Osório, Simone Andréa Pozza https://creativecommons.org/licenses/by-nc/4.0
Theoretical Analysis of Growth and Collapse of Spherical Cavities
In the present study, the analytical equations of conical functions are used to describe the growth and collapse of vapor and spherical cavities in liquids (cavitation). The equations describing the expansion of the spherical finite universe from the cosmological models are also applied to the study of growth and collapse of vapor and air cavities within liquids. The relative simple method used here has the advantage of prescinding numerical and/or computational simulations and other methods. Although the differences between the results of the adiabatic collapse and the isothermal collapse are very small, according to the literature. The hypothesis of the isothermal collapse of the bubble is used and justified based on the concept of characteristic time for heat transfers. Consequently, available theoretical and experimental data for isothermal collapse of such cavities are also used and, in the sequence, adjusted to polynomial equations. These were used to describe the radius as a function of time during the collapse and growth of the cavities. An auxiliary function was used here with the time variable, resulting in a linear function of it. The results are presented in graphs showing the bubble radius as a function of time, for collapse or growth of the cavity, or bubble.
Copyright (c) 2025 Gil Bazanini, Ricardo Kirchhof Unfer https://creativecommons.org/licenses/by-nc/4.0
High-Performance Audio Power Amplifier with a Push-Pull Voltage Amplification Stage and Active Loads in the Input Differential Pair
The paper proposes an innovative way to connect a differential stage with a current mirror as its load to a voltage amplification stage (VAS) without using gain-limiting resistors, employing a "buffer-bias" stage to stabilize the VAS current and preserve circuit performance. The effectiveness of the proposed topology was demonstrated through measurements on a functional prototype, which exhibited high amplifier performance, such as a total harmonic distortion of 0.0008% at 1 kHz even at full power (50WRMS) and a slew rate of 107.4V/μs.
Copyright (c) 2025 Alexandre Saciotto Levorato, Carlos Alberto de Francisco https://creativecommons.org/licenses/by-nc/4.0
Phytochemical Analysis and Antioxidant Activity Assessment of Croton linearifolius Stem Extracts
Croton linearifolius is a species with promising medicinal potential. This study investigated the antioxidant activity, total phenolic and flavonoid contents, and conducted chemical prospecting of its ethanolic stem extract and fractions. The extract was obtained by exhaustive percolation with 70% hydroethanolic solution, followed by liquid-liquid partitioning using hexane, dichloromethane, and ethyl acetate. In vitro tests were used for chemical analysis, and antioxidant activity was evaluated by DPPH and FRAP methods. The ethyl acetate fraction showed the highest antioxidant activity (80.62% in DPPH), with elevated phenolic and flavonoid levels, indicating potential for herbal medicine development.
Copyright (c) 2025 Cleia Teixeira Santos de Franca, Marcel Mark da Silva Passos, Matheus Andrade Rocha Costa, Esaul Lucas Oliveira, Simone Andrade Gualberto https://creativecommons.org/licenses/by-nc/4.0
Topic Modeling of Bot Preferences in Tweets from the COVID-19 Parliamentary Inquiry in Brazil
Twitter is a microblogging social network that allows users to send and receive short messages in text and image format, being one of the most widely used platforms of its kind. Given its relevance in various aspects of contemporary society, including politics, many users operate automated profiles (bots) that post hundreds or even thousands of tweets. This study applies the Latent Dirichlet Allocation (LDA) technique to identify whether bot users show preference for any of the modeled topics. Data were collected via the Twitter API between April 18 and May 30, 2021, using the keywords "CPI" (Parliamentary Inquiry Committee) and "COVID," resulting in 459,145 tweets in Portuguese from 109,027 distinct users. These users were analyzed through the Pegabot platform, which estimates the probability of an account being a bot. After preprocessing, only the users with 100 or more tweets during the period were retained, resulting in 26,966 observations from 189 accounts. LDA identified four main Topics: 1 - Health Secretary; 2 - senator Renan Calheiros; 3 - president Jair Bolsonaro; and 4 - the government. In all topics, bot accounts posts were more frequent than human users posts, with Topic 1 having the lowest proportion of accounts classified as bots.
Copyright (c) 2025 Gabriel Thompson Marques Arruda, Anderson Castro Soares de Oliveira, Lia Hanna Martins Morita, José Nilton da Cruz https://creativecommons.org/licenses/by-nc/4.0
Test of Equality of Parameters in Growth Curves of Black Castellana Chickens
Growth curves and the understanding of sexual dimorphism provide information for increasing productivity in the poultry industry. The study aims to describe the growth of male and female Castellana Negra chickens using the nonlinear Gompertz model and applying the Likelihood Ratio Test (LRT) to compare model parameters to investigate sexual dimorphism. The data were obtained from an experiment involving male and female Castellana Negra chickens. The Gompertz model was adjusted to the data using the maximum likelihood method, and the LRT was employed to assess the equality of growth curve parameters between sexes. The full Gompertz model, in which parameters varied between males and females, proved to be the most suitable for describing the growth of the animals. Therefore, the Castellana Negra breed presents sexual dimorphism in relation to adult weight, the age at maximum growth rate, and the relative growth rate.
Copyright (c) 2025 Rafaela de Carvalho Salvador, Natiele Almeida Gonzaga, Edilene Cristina Pedroso Azarias, Adriele Aparecida Pereira, Tales Jesus Fernandes https://creativecommons.org/licenses/by-nc/4.0
Cracks Detection in Concrete Surfaces using Machine Learning
In this study, Machine Learning techniques were used to detect cracks in concrete surfaces. Texture descriptors were extracted from a set of images of cracked and non-cracked concrete surfaces using Gray Level Co-occurrence Matrix (GLCM). Texture descriptors features were used to train four machine learning models: Logistic Regression, Artificial Neural Networks, Random Forest, and eXtreme Gradient Boosting (XGBoost). k-fold cross validation was used to evaluate the performance of the models as well as metrics such as accuracy, sensitivity, precision, F1-score - the harmonic mean between precision and sensitivity - and the Area Under the ROC Curve (AUC). The results indicate satisfactory performance of all models, with emphasis on the XGBoost model, which achieved 99.65% accuracy and 99.70% sensitivity.
Copyright (c) 2025 Antonio Mendes Magalhães Júnior, Ícaro Viterbre Debique Sousa, Heron Viterbre Debique Sousa, Thelma Sáfadi, Paulo Henrique Sales Guimarães https://creativecommons.org/licenses/by-nc/4.0
This study is based on the following hypothesis: "Is it the greater the municipality's population, the greater the number of cancer cases?" To investigate this question it was created a map of childhood cancer cases by municipality that are served by the NGO Viver, with the goal of comparing the data with the population of the municipalities served. Using the QGIS software, the cases were superimposed on the map of Paraná to visualize the spatial distribution. In addition, comparative graphs between the population and the number of cases were generated to verify the existence of a correlation. Due to the case concentration in the northern region of the state, municipalities outside of this area were discarded to minimize data variation. The data were equalized based on Londrina statistics, a major health hub, assuming that all city cases are treated locally. There was a variation in the results with municipalities presenting more than 8 cases above average and others 4 fewer than expected. Although more populous municipalities generally present more câncer cases, some exceptions were identified which suggests the need for future investigations to understand these deviations.
Copyright (c) 2025 Igor Henrique de Sousa Palmar, Viviane de Alvarenga, Osvaldo Coelho Pereira Neto https://creativecommons.org/licenses/by-nc/4.0