Teses em Engenharia de Recursos Naturais da Amazônia (Doutorado) - PRODERNA/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/4045

O Doutorado Acadêmico inicou-se em 2006 e pertence ao Programa de Pós-Graduação em Engenharia de Recursos Naturais da Amazônia (PRODERNA) do Instituto de Tecnologia da UFPA (ITEC) da Universidade Federal do Pará (UFPA).

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Acesso aberto (Open Access)
Análise de vibrações mecânicas em estruturas esbeltas e flexíveis, como cordas e vigas, sujeitas à movimentação axial utilizando a técnica da transformada integral generalizada
(Universidade Federal do Pará, 2024-05-28) PORFÍRIO, Rogilson Nazaré da Silva; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785; https://orcid.org/0000-0001-9365-7498
The dynamic analysis of vibrations on flexible structures is of an extreme importance in engineering and its solution represents a significant challenge to be tackled. This study has the objective to investigate thin and flexible structures such as beams and ropes, that oscillate in supports clamped-clamped and clamped-concentrated mass, which determine the boundary conditions of the analysis problem. Using the generalized integral transformation technique (GITT) that converts the partial differential equation (PDE) developed by the Hamiltonian method in an Ordinary Differential Equation (ODE), it optimizes the numerical process andcontrols efficiently the relative error of the calculations. In this study, it was developed and applied an innovative method that treats the boundary conditions without the use of filters to homogenize the equations. The calculations methodology was implemented in Fortran, utilizing a sub-routine DIVPAG of IMSL. As reference, a thorough analysis of convergence and stableness was applied, considering the behavior of four different models of ropes and two models of beams. The validation of methodology was approached comparing functional aspects such as transversal displacement, system velocities, frequencies, and damping, with results obtained by GITT and other studies that applied the same simulation conditions. The results of this study were found to be satisfactory, which highlights the relevancy of application of this vibration analysis method. It was also assessed the application of this method in different vibration configurations in each model, which exemplifies its broad potential in problems involving the structures analyzed. Therefore, this study represents a significant contribution to the advance of knowledge in dynamic modeling of thin and flexible structures and highlights the influence of boundary conditions in vibrational characteristics of these structures.Furthermore, it introduces an innovative methodology for treating boundary conditions without the use of filters, expanding the analysis possibilities in this field of engineering.
Acesso aberto (Open Access)
Aplicação de destilados provenientes do bio- óleo de pirólise de resíduos de gordura animal no asfalto diluído de petróleo
(Universidade Federal do Pará, 2024-08-12) VALENTE, Alex Lopes; MACHADO, Nélio Teixeira; http://lattes.cnpq.bhttp://lattes.cnpq.br/1500327307736428r/5698208558551065; https://orcid.org/0009-0002-4461-7611; BERNAR, Lucas Pinto
Waste animal fats (WAF) can be converted into distillate fractions similar to petroleum solvents and used as biofuels or in other applications through pyrolysis and fractional distillation. The distillate fractions from the pyrolysis of triglycerides exhibit adequate viscosity and volatility compared to petroleum-derived fuels but show acid values between 60-140 mg KOH/g, preventing their direct use as biofuels without considerable purification of the distilled fractions. Diluted petroleum asphalt (DPA), used for priming soil in the construction of flexible pavement, requires adequate viscosity, volatility, and penetration, and the distillate fractions from WAF pyrolysis oil can be used as partial or full substitutes for the standard solvent (kerosene) in DPA production. The aim of this study was to test the compliance of DPAs prepared by substituting kerosene with bio-oil fractions from WAF according to DPA standards. First, WAF is obtained from meat waste through the rendering process. Then, WAF is subjected to pyrolysis in a semi-batch fixed-bed reactor (2L), and the resulting bio-oil is fractionally distilled into gasoline, kerosene, and diesel fractions. The pyrolysis process is analyzed concerning the type of reactor used, with a focus on the influence of temperature and reaction time, as well as the distillation profile. The distilled fractions are characterized by density, viscosity, and acid value before being used in the preparation of DPAs by partial and/or total (0-40% by weight) substitution of standard kerosene. The mixtures were tested for kinematic and Saybolt-Furol viscosity, flash point, and penetration, according to road pavement standards. The results showed that the kerosene and diesel fractions from WAF can be adequately used in the preparation of DPAs as a total substitute for the petroleum kerosene typically used.
Acesso aberto (Open Access)
Avalanche como rede de percolação não homogênea
(Universidade Federal do Pará, 2019-09-13) SOUZA, Raimundo Nonato Carneiro de; TAVARES, Heliton Ribeiro; http://lattes.cnpq.br/1313373547379006; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
Avalanches can be considered as a percolation process. This hypothesis will be posted to evaluate if this approach is possible and what are its advantages. Some literature speculates that there is the possibility of considering avalanches as a percolation event. However, there is no clear distinction from the percolation model that these events describe, either a homogeneous or non-homogeneous process. This work deals with avalanche simulations as physical cases of percolation. To characterize the avalanches, two percolation models were simulated: homogeneous and heterogeneous. Simulations were developed to compare avalanches in both models. To perform these simulations, the probability of a site being open equal to 0:5 was used. The sizes and transients were measured for each avalanche in the different models. To close the work, experiments were carried out to create avalanches, in order to better calibrate the simulations using real avalanche data. For when comparing the simulated results with existing data in the literature, a typical behavior of a probability function was perceived. Given this behavior one can make predictions about the size of the avalanches. Analyzing the results obtained, it is possible that the behavior of avalanches created with non-homogeneous probability presented well defined characteristics, having larger values of size and transient. It was concluded that the non-homogeneous model has a high stability and is better in the evolution aspect of the avalanche, so with some adjustments the heterogeneous model can approach a real avalanche with greater accuracy.
Acesso aberto (Open Access)
Caracterização morfológica, cristalina e textural de bio-adsorventes produzidos via processamento hidrotérmico de resíduos de palha de milho com H2O sub-crítica: Aplicação na adsorção de ácido acético.
(Universidade Federal do Pará, 2021-12-06) COSTA, Maria Elizabeth Gemaque; MACHADO, Nélio Teixeira; http://lattes.cnpq.br/5698208558551065
This work aims to investigate the influence of temperature on the textural, morphological and crystalline characterization of bioabsorbents produced by hydrothermal processing of corn husk residues with hot compressed H2O. The experiments were carried out at 175, 200, 225 and 250 ºC, 240 minutes, heating rate of 2.0 ºC/min and biomass/H2O ratio of 1:10, using a pilot scale reactor of 18,927 L. The process is analyzed in terms of yields of reaction products as a function of temperature. The results showed yields of solids ranging from 62.92 to 35.82% (weight), gas yields ranging from 1.49 to 9.59% (weight) and liquid products ranging from 35.43 to 54.59% ( Weight). The yield of the solid phase decreases with temperature, presenting an inflection region between 200 and 225 °C, in which a drastic change occurs, while that of the liquid phase increases, presenting the same inflection region between 200 and 225 °C. The gas phase yield increases exponentially with temperature up to approximately 10% (weight) in the investigated temperature range. Elemental analysis of solid products shows that the carbon content increases, while the oxygen and hydrogen content decreases with temperature. The textural, morphological and crystalline characterization of solid phase products analyzed by TG/TDG, SEM/EDX, XRD and BET. The solid phase product (bio-adsorbent) obtained by hydrothermal processing of corn husk residues at 225 and 250 °C, 240 minutes, and biomass/H2O ratio of 1:10, were chemically activated with 2.0 NaOH solutions. M and 2.0 M HCl to investigate the adsorption of acetic acid solutions (1.0; 2.0; 3.0; and 4.0 mg/mL). The adsorption kinetics investigated at 30, 60, 120, 240, 480 and 960 seconds. The adsorption isotherm showed that chemically activated carbons were able to remove acetic acid from aqueous solutions.
Acesso aberto (Open Access)
Descontaminação de máscaras N95 em hospital público de Belém/PA: apresentação e avaliação de protocolo simplificado
(Universidade Federal do Pará, 2024-11-25) MATTOS, Simone Lopes de; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste. Descriptors: Decontamination. Ultraviolet Rays. Radiation Dosimeters. Personal Protective Equipment. Respiratory Protection Devices. biosecurity.he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste. Descriptors: Decontamination. Ultraviolet Rays. Radiation Dosimeters. Personal Protective Equipment. Respiratory Protection Devices. biosecurity.he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste. Descriptors: Decontamination. Ultraviolet Rays. Radiation Dosimeters. Personal Protective Equipment. Respiratory Protection Devices. biosecurity.he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste. Descriptors: Decontamination. Ultraviolet Rays. Radiation Dosimeters. Personal Protective Equipment. Respiratory Protection Devices. biosecurity.he author presents a protocol for decontamination of N95 filter masks by means of short wave ultraviolet irradiation (UV-C), as well as the results of the microbiological validation testing of the UV-C device and qualitative research on the adherence of professionals from the João de Barros Barreto University Hospital, of the University Hospital Complex of the Federal University of Pará (HUJBB) to the aforementioned protocol. The microbiological tests demonstrated the efficacy of the decontamination protocol, as there was no bacterial growth in culture media inoculated with swabs of masks used in the hospital and decontaminated in the UV-C device, which proved the germicidal efficiency of UV-C irradiation. The results of the qualitative research point to the adherence of nursing professionals to the practice of mask decontamination, recognizing the practicality and contribution of the protocol to biosafety and occupational safety. As part of the same protocol, an alternative packaging for storing masks in the intervals of use of N95 masks is presented, considering their safe reuse. The protocol also has the following advantages: low cost and practicality of use, in addition to contributing to the reduction of infectious waste.
Acesso aberto (Open Access)
Energy generation by renewable hybrid sources with pumped storage
(Universidade Federal do Pará, 2022-10-25) FURTADO, Gilton Carlos de Andrade; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
With the increase in the use of renewable sources, the need for energy storage becomes important to ensure that energy generation can meet the demand for electricity. This work aims to explore the potential of energy generation and storage existing in hydroelectric plants and dams. The case of Tucuruí is analyzed, in which the locks and the islands formed in the upper reservoir offer the opportunity to implement renewable systems. In a literature review, similar systems existing in the southern hemisphere are researched, with emphasis on the cases of Brazil and Africa. For the locks, initially, the feasibility of implementing a solar with pumped storage hybrid system is evaluated, comparing it with a purely photovoltaic proposal. In sequence, an optimized system is proposed considering the tariff differences provided in the rules of the Brazilian electricity sector. On the studied island, the advantages of using pump as turbines as a means of energy production and storage are analyzed. The cases studied showed interesting results from a technical and economic point of view, presenting below average payback times, reduced initial investments and ease of maintenance. The physical structure of the already existing locks and dams is favorable to systems of this nature, demonstrating that the expansion of waterway transport in Brazil and in the world must be planned to provide energy storage in sync with renewable generation sources.
Acesso aberto (Open Access)
Estudo da eficiência de uma turbina hidrocinética com difusor projetada para o aproveitamento da energia remanescente da barragem de Tucuruí
(Universidade Federal do Pará, 2023-05-15) LIMA, Adry Kleber Ferreira de; LINS, Erb Ferreira; http://lattes.cnpq.br/5272283698536321; https://orcid.org/0000-0002-6643-5889; VAZ, Jerson Rogério Pinheiro; http://lattes.cnpq.br/1623983294183975; https://orcid.org/0000-0001-6440-4811
Harnessing the remaining energy downstream of dams has recently attained great attention as the kinetic energy transported by the water current is indeed considerable. This work develops a study on the performance of a horizontal-axis hydro turbine under di!user e!ect, in order to quantify the energy gain by comparing both turbines with and without di!user. A 3-bladed hydro turbine with 10 m diameter shrouded by a flanged conical di!user is employed. A numerical modeling using computational fluid dynamics is carried out based on the Reynolds Averaged Navier-Stokes formulation, using the Ÿ – Ê – SST (Shear Stress Transport) turbulence model. The results yield good agreement with experimental and theorical data available in literature.
Acesso aberto (Open Access)
Estudo da resistência à corrosão de soldas de ferro fundido branco alto cromo na presença de NaOH (30% p.p)
(Universidade Federal do Pará, 2024-10-03) SANTOS, Renata Soraia Guimarães dos; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500; https://orcid.org/0000-0003-0739-7592
In the mining industry, specifically in bauxite beneficiation, adverse working conditions are encountered, requiring high mechanical and chemical resistance. For these conditions, it is necessary to choose potentially resistant materials, such as high Cr white cast iron (FFBA-Cr). However, currently, there is no effective recovery of equipment manufactured with FFBA-Cr, mainly due to the difficulty of machinability generated in the repair process. An alternative recovery has been developed by the Laboratory of Characterization of Metallic Materials of UFPA - LCAM, through electric arc welding, using two filler metals, the electric wire ER307L and the wire with high Mn value. In this context, this work proposes to investigate the corrosion resistance of the welded joint, obtained with these two filler metals. The base metal (FFBA-Cr) as a reference and the metals generated by the welded joints, ER307L and with high Mn value, were analyzed. The samples underwent optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and electrochemical tests of corrosion potential, polarization and impedance. It was observed that the samples presented a similar structure of carbide matrix, but with different organization and volumes. However, the electrochemical behavior of corrosion potential, polarization and impedance were similar, with their resulting values very close, variations: 50 V; 3.53 µA; 0.18 ohm, respectively, which was corroborated by the corrosion rate, 0.4 mmpy, and explained by the calculations of Cr and Ni volume, which present inverse values of concentration magnitude between the samples. Raman analyses performed after polarization of the samples indicated the formation of important oxides on this surface and possibly the formation of a passivating layer, which is corroborated by the mass loss analysis that showed the possibility of passivation of the welded joints, despite corrosion processes in the anodic phase of this exposure process over the exposure time.
Acesso aberto (Open Access)
Interações com nanotubos de carbono e pontos quânticos de óxido de grafeno com estruturas externas do Sars-cov-2 via simulações de dinâmica e docagem molecular
(Universidade Federal do Pará, 2023-06-02) LOBATO, Júlio César Mendes; OLIVEIRA, Mozaniel Santana de; http://lattes.cnpq.br/0810227136654245; https://orcid.org/0000-0002-4076-2443; CHAVES NETO, Antonio Maia de Jesus; Lattes: 3507474637884699
The interaction between nanoparticles and SARS-CoV-2 virus proteins was evaluated using ligands such as single-walled carbon nanotubes (NTCPUs) and receptors including envelope protein (E-pro), major protease (M-pro) and Spike glycoprotein (Sgly). Molecular docking modeling and molecular dynamics techniques were applied. Molecular dynamics revealed root mean square shift of atomic positions ranging from 0.5Å to 3.0Å. The results indicated that the zigzag nanotube showed better affinity energy, with binding free energy values of -9.48, -9.98 and -10.08 kcal/mol for E-pro, M-pro and S-gly, respectively. Furthermore, the mean square deviation of the atomic positions remained more stable for this type of nanotube, indicating a high probability of binding to the active sites of the macromolecules. Molecular couplings and binding free energy showed strong interaction between NTCPUs and residues of the S-gly active site, with values of -112.73, -94.38 and -80.49 kcal/mol for zigzag, chiral and armchair ligands, respectively. In a second step, five graphene oxide (GO) quantum dots smaller than 20 nm were used as ligands, interacting only with the spike receptors of three different strains: S-GLY-OMICRON, S-GLY-KAPPA and S-GLY-DELTA. Comparing the two ligands, it was observed that the S-GLY-OMICRON/OG-E interaction showed better affinity with Gibbs free energy of 172.2510 KJ/mol, compared to the better affinity of carbon nanotubes, S-gly/zig-zag, with ΔG of -112.73 KJ/mol. The eight proposed ligands have a high probability of binding to the active sites of the macrostructures. In conclusion, both carbon nanotubes and OG showed promise for application in SARS-CoV-2 inhibitor products, such as the development of materials for the manufacture of personal protective equipment, sprays and waterproofing solutions in general.
Acesso aberto (Open Access)
Modelagem numérica-experimental da produção de sedimentos de pequenas bacias hidrográficas da Amazônia
(Universidade Federal do Pará, 2021-04-22) BARBOSA, Ana Júlia Soares da Silva; BLANCO, Claudio José Cavalcante; http://lattes.cnpq.br/8319326553139808; https://orcid.org/0000-0001-8022-2647
Erosion is a process of direct impact in urban and rural environments. The understanding of this process requires the use of models and techniques of geoprocessing and field, for approximate estimation of the realized one, since it is a phenomenon with many variables to be taken into account. For the present study, two models were used to generate data in a small Amazon basin. The USLE (universal soil loss equation) and also the modified MUSLE version. For both models, the common factors (K, LS, C and P) were determined. For USLE, the calibration occurred for rain erosivity, which is the differential factor of this model. After USLE application with calibrated R factor, the model was applied to the study area with an average soil loss of 1.99 ton. ha-1.year-1, for a period of 21 years. For MUSLE, the differential variables are the hydrological variables (Q and qp) were determined by analyzing the hydrographs observed with the aid of a digital filter. Two methods of calibration and validation have been done for MUSLE. Method 1 calibrated the factors ɑ and b, with sediment production data measured from 62 flood events from 2012 to 2014. The values found for factors ɑ and b were equal to 19.90 and 0.60, respectively. MUSLE was validated with sediment production data measured from 62 flood events in the years 2014 and 2015. The validated MUSLE equation represented in a satisfactory way, in more than 70%, the data of soil loss observed in the hydrographic basin of the Igarapé da Prata. Method 2 calibrated only the value of a, using the solid discharge curve with potential regression for the years 2012 and 2013, which showed R² of 0.70 and 0.68, respectively. The value of ɑ obtained was 17.25, and was applied to MUSLE, keeping the value of b at 0.56, the original value of the model. The validation for the latter method proved to be adequate, with an R² of 0.69. These results validate the empirical models for the region with experimental activities, which corroborates for the production of sediment information in the Amazon region, as a way of maturing and the search for new research, for the understanding of the impacts arising from the transport of soil between areas and in the water environment.
Acesso aberto (Open Access)
Modelos matemáticos de transferência de calor e massa: extração de metais por membranas poliméricas e sinterização de materiais cerâmicos
(Universidade Federal do Pará, 2024-07-16) VILHENA, Mailson Batista de; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The overall objective of this work was to present a mathematical study of multicomponent mass transfer in a metal ion extraction cell through a flat polymeric membrane and to conduct an experimental and kinetic study focused on the production of synthetic aggregate from bauxite residue. In the first part of the work, a mass transfer model for the recovery of metal ions using flat polymeric membranes was developed. Unlike most existing models, which are limited to studying a single component and do not consider the selectivity and effects of multiple components on reaction kinetics, a model capable of simulating the simultaneous extraction of various metals is proposed. This model is based on the mass conservation equation and was solved using the Coupled Integral Equations Approach (CIEA), and validated with experimental measurements and previous simulations. In the second part, an experimental and theoretical study was conducted using a kinetic model for the production of coarse synthetic aggregates from bauxite residue, silica, and clay. The experimental study included the production and characterization of the aggregates in different compositions. To analyze the sintering process of a full-sized pellet, a small electric furnace with an attached balance was built, allowing the monitoring of mass loss measurements as a function of temperature and time. Additionally, a kinetic study was carried out using mathematical models to evaluate the main solid-state reactions and their phase transformations during the sintering process, using experimental data from thermal analysis.
Acesso aberto (Open Access)
Nanofiltração de hormônios e metais pesados em nanotubos de carbono e de boro por dinâmica molecular
(Universidade Federal do Pará, 2020-02-27) CAVALEIRO, Rosely Maria dos Santos; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; https://orcid.org/0000-0002-9730-3512
Sewage treatment stations receive various effluents and perform the selective filtering of molecules that can, if they persist in the water, contaminate or the environment. Selection processes initiated by larger sections down to nanoparticles. Among the molecules called emerging contaminants are hormones and heavy metals that impact on graves consequences on organisms by endocrine-disrupting action. When surface waters receive effluents with traces of contamination and hormones or heavy metals, they will cause diseases in living beings, especially in pregnant women and children, as well as interfering in the chains of DNA, also affecting the next generations. This study of molecular tests carried out with nanofiltration: water with hormones and water with heavy metals filtered through carbon nanotubes and boron nitrogen, under the action of 8 (eight) electric fields lasting 100 (hundred) ps. The study hormones were: estrone, estradiol, estriol, progesterone, ethinylestradiol, levonorgestrel, diethylbestrol, and heavy metal ions: lead, cadmium, iron, zinc, and mercury. Each of the hormone molecules and the heavy metal were filtered through two nanotubes, under the same boundary conditions. The selected results that allow creating nanofiltration systems that can be removed micropollutants using carbon nanotubes or boron nitride activated by the uniform electrical fields from 10-5 a.u. to 10-8 a.u.
Acesso aberto (Open Access)
Obtenção de extratos com potencial bioativo a partir da polpa do piquiá (caryocar villosum (aubl.) pers.) utilizando dióxido de carbono no estado supercrítico
(Universidade Federal do Pará, 2024-09-30) CORDEIRO, Renato Macedo; CARVALHO JÚNIOR, Raul Nunes de; http://lattes.cnpq.br/5544305606838748; https://orcid.org/0000-0002-4433-6580
In a context of increasing demand for substances with health-beneficial properties, extracts from certain plant species found in the Amazon are a promising source of bioactive compounds. Caryocar villosum (Aubl.) Pers., a native fruit of the Amazon region commonly known as piquiá, is regarded as a source of bioactive compounds. This study investigated the supercritical extraction process of piquiá pulp to evaluate the process parameters, overall yield, extraction kinetics, fatty acid profile, α-tocopherol content, functional quality, and physicochemical characterization. The influence of extraction temperature, pressure, and solvent density on the extraction yield was considered. The quality of the obtained extracts was assessed in terms of fatty acid profile, functional quality indices, physicochemical characterization, and α-tocopherol content. A kinetic study of the piquiá extraction with supercritical fluid was conducted using experimental data and mathematical models. The extraction yield was found to increase with pressure at each isotherm, with the highest yield reaching 62.74% and the lowest at 44.01%. The kinetic mathematical models of Martinez and Barton demonstrated good performance in correlating the extraction process of piquiá pulp. The primary fatty acids observed in the extracts obtained under all operational conditions were oleic and palmitic acids. The extract obtained at the operational condition of 60 °C and 250 bar exhibited the highest α-tocopherol content compared to the other experimental conditions in this study. The results indicated that the extracts from piquiá pulp obtained through supercritical CO₂ extraction present significant potential for the industry due to their functional quality.
Acesso aberto (Open Access)
Obtenção do óleo e da polpa sem gordura do açaí (euterpe oleracea) por extração supercrítica: caracterização físico-química, estudo da citotoxicidade e vida de prateleira
(Universidade Federal do Pará, 2025-01-06) SIQUEIRA, Letícia Maria Martins; BRASIL, Davi do Socorro Barros; http://lattes.cnpq.br/0931007460545219; https://orcid.org/0000-0002-1461-7306; CARVALHO JÚNIOR, Raul Nunes de; http://lattes.cnpq.br/5544305606838748; https://orcid.org/0000-0002-4433-6580
Açaí is a very important product for the development of the state of Pará, for the bioeconomy and the market has been growing. And currently the majority of the state’s production is just fruit pulp, hence the importance of new products with added value and the need to invest in new sustainable processes for the region’s development. Therefore, the objective of this work was to obtain the oil and pulp without açaí fat by supercritical extraction, determine the main bioactive compounds, evaluate the possible cytotoxicity in MRC-5 and VERO cells in vitro and evaluate the shelf life of the products. The freezedried açaí pulp was subjected to extraction with supercritical CO2, under the conditions 323,15 K at 35 MPa, 333,15 K at 42 MPa and 343,15 K at 49 MPa. The highest yield (51,74 %), carotenoids (277,09 μg/g), DPPH (2,55 μmol TE/g), ABTS (2,60 μmol TE/g) and FRAP (15,25 μm ferrous sulfate/g) from oil and ABTS (644,23 μmol TE/g) from pulp without fat were found at 343,15 K at 49 MPa condition. The highest contents of phenolic compounds (150,20 mg GAE/g d.b.), DPPH (414,99 μmol TE/g d.b.) and FRAP (746,2 μm ferrous sulfate/g) from pulp without fat were found at 323,15 K at 35 MPa condition. The pulp without fat presented high levels of anthocyanins without significant variation. The products did not present cytotoxicity. The half-life of the freeze-dried pulp and the fat-free pulp in the presence of light (Becker) was shorter than that of the packaging materials. The sealed packaging achieved a longer half-life compared to vacuum-sealed packaging for the freeze-dried pulp. However, for the fat-free pulp, the vacuum-sealed packaging showed a longer half-life compared to the sealed one. The results of the stability of açaí oil qualify it as a table oil rather than a frying oil, as it degrades more rapidly at higher temperatures. The results demonstrated that the products have potential applications in the industry.
Acesso aberto (Open Access)
Secagem de açaí branco por liofilização e em leito de jorro: influência da concentração e de diferentes agentes carreadores nas características físicas, químicas, bioativas e colorimétricas do pó obtido
(Universidade Federal do Pará, 2024-04-05) BARROS, Hellen Carvalho; COSTA, Cristiane Maria Leal; http://lattes.cnpq.br/0581730621014796; FARIA, Lênio José Guerreiro de; http://lattes.cnpq.br/7428609361678173; https://orcid.org/0000-0002-9534-9998
The objective of this study was to analyze how the use of four different carrier agents (modified starch, gum arabic, maltodextrin and hydrolyzed collagen) and different concentrations (10, 20 and 30%) influence the white açaí powder produced by lyophilization and in a bed of gush. Yield, moisture, total polyphenols, antioxidant activity, hygroscopicity, solubility, fluidity, color, chemical structure, and morphology were the responses evaluated. In freeze-drying, the yield of the process (≥ 75.40%) and the moisture content of white açaí powder (≤ 4.93 g 100 g- 1) did not differ statistically (p ≤ 0.05), regardless of the agent carrier used. In spouted bed drying, the addition of modified starch or hydrolyzed collagen promoted higher process yield (≥ 42.70%). However, the white açaí produced with hydrolyzed collagen was the only one that had a moisture content ≥ 6.00 g 100 g-1. In both drying processes, powders produced with modified starch were less soluble (≤ 48.96%), despite low hygroscopicity (≤ 13.73 g 100 g-1). Samples produced with maltodextrin or gum arabic showed higher levels of total polyphenols (≥ 8.52 mg EAG g-1) and antioxidant activity (≥ 42.75 μmol ET g-1). In addition, they were more soluble (≥ 94.36%), fluid (11 to 15% according to the carr index), and better preserved the original color of the pulp to the detriment of other formulations. The chemical structure of white açaí powders obtained with different carrier agents was like that of the pulp, indicating efficient encapsulation of bioactive compounds and good preservation of functional groups present in the original raw material, even after drying processes.
Acesso aberto (Open Access)
Secagem de minério de ferro em vagões e pilha: experimentos e simulação computacional
(Universidade Federal do Pará, 2023-05-26) FURTADO, Maciel da Costa; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
Dust emissions resulting from handling and transporting particulate materials are a problem in the mining industry. These emissions are more accentuated when the materials are not very humid because the reduced humidity makes the particles lighter and more susceptible to dispersion. Faced with these issues, this study proposes a methodology for the theoretical and experimental study of the drying process that occurs when iron ore fines are transported in wagons or stored in piles in the open. The objective is to clarify the effect of surface moisture in the process of dragging wind iron ores on moist surfaces, such as those found when transporting iron ore in open wagons and in ore pile storage yards. In this study, wind tunnel tests were carried out using a wagon model with fine iron ore and an iron ore pile model. A fixed bed drying study at low velocity is also presented using a wind tunnel dryer. A numerical CFD model was developed, and the results agreed well with the experimental results. The numerical model allowed the evaluation of the drying behavior for different values of air flow velocity. Through the established study methodology, it was possible to map the distribution of internal moisture in the bed, which helps to understand the dynamics of the drying mechanism and how this can influence the emission of particles on the surface moisture of these materials.
Acesso aberto (Open Access)
Sensores de narcóticos, gás natural e syngás utilizando nanotubos de carbono sob ação de campo elétrico externo
(Universidade Federal do Pará, 2021-02-15) AIRES, Júlio Cesar Nunes; CHAVES NETO, Antonio Maia de Jesus; http://lattes.cnpq.br/3507474637884699; https://orcid.org/0000-0002-9730-3512
This work presents an analysis of the molecular dynamics between several illicit drugs: benzoylmethylecgonine, diacetylmorphine, 3,4 methylenedioxymethamphetamine, D-Deoxefedrine, lysergic acid diethylamide and, interacting with a section of carbon nanotubes at low initial temperature, corresponding to 10-3 K, and under a uniform electric field, like a drug detection system. In addition to the analysis of the behavior of natural gas molecules and SYNGAS interacting with a carbon nanotube at an initial simulation temperature of 300K, with all systems being relaxed by 50 ps outside the carbon nanotube, describing each possible arrangement for capture; a constant external electric field was then applied to the systems, longitudinally, along the length of the carbon nanotube, promoting an evanescent effect, capable of trapping them orbiting the carbon nanotube. Simulations for electric field intensities within a range of 10-5 to 10-1 a.u. were performed, to verify the behavior of drugs, while for the molecules that comprise Natural Gas and SYNGAS, a range of 10-8 to 10-1 a.u. was adopted. Average orbital radii were estimated, in addition to a number of thermodynamic properties. Our results indicate that the combination of a uniform external electric field and van der Waals interactions in a carbon-derived nanotube is enough to create an evanescent field of attractive potential, modeling it as a system for the detection of temperature and drug rays .
Acesso aberto (Open Access)
Viabilidade da geração de energia a partir de resíduos sólidos urbanos em pequenos municípios do estado do Pará
(UFPA - Universidade Federal do Pará, 2022-07-01) PADILHA, Jessé Luís; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
The most common urban solid waste disposal in Brazil is the landfill. Additionally, there are still inadequate disposal units (dumps), but there are technological alternatives for this disposal and some projects are already installed in Brazil. The economic analysis is therefore fundamental to find the best technological option, transforming an environmental problem into a viable solution. This work aims to analyze the financial viability of the combination of consolidated destinations for the management of Municipal Solid Waste (MSW) (technological routes), that use Waste-to-Energy (WTE), considering small cities with populations from 30,000 to 250,000 residents and later apply this analysis considering the grouping of municipalities in Pará, suitable according to the regional plan for solid waste in the state of Pará. A structured algorithm was used with a focus on estimating revenue from the minimum value of rate payers' contributions (RPC) to make these routes viable for most cities considered in the project. Economic indicators used include: Net Present Value (NPV), Internal Rate of Return (IRR), Discounted Payback Period (DPP), and Leveled Cost of Electricity (LCOE). A sensitivity analysis of the two best routes was performed (depending on lower RPC values) based on NPV. The results tend to confirm solutions that can be approved not only by the government, but also by the business sector. The best outcomes are the routes with landfill and landfill gas, and with recycling and anaerobic digestion, considering the sale of digestate and landfill. These presented the best financial values, with discounted payback periods of 15 and 20 years, maximum RPC of US$0.04 and US$0.33, per inhabitant/month, respectively, with an IRR of 11.61%, for both. The sensitivity analysis indicated a greater influence on the investment costs of landfill gas for the first route and for the second route, the urban collection and cleaning services and the estimated average percentage of the population's half-minimum-wage income expenditure was on average a little above 3%.
Acesso aberto (Open Access)
Viabilidade operacional de emprego do processo HW-GMAW em aços
(Universidade Federal do Pará, 2023-05-19) RIBEIRO, Pedro Paulo Guimarães; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500; https://orcid.org/0000-0003-0739-7592
This study investigated the operational viability of the HW-GMAW variant of the GMAW process in steels welding compared to the CW-GMAW and GMAW processes. This study has been conducted in the two phases. In the phase I beads on plate welding were performed on ASTM -131 grade A rating steel, varying the additional wire feed rate by 40%, 80% and 120% for CW and HW and current at 40 A and 80 A. In phase II an AISI 1020 classification steel were used, varying the additional wire rate by 20% and 100% HW and the current in 70 A.The statistical tools used considered that results were affected by current and wire feed rate (phase I) and the polarity, feed rate of wire and torch displacement orientation (phase II). Phase I results showed that the HW-GMAW process increased depth of penetration by 27% over the CW-GMAW process at up to 32% lower dilution levels over the GMAW when the feed rate was 120%. In the phase II, the capture of high-speed image in the study of electric arc dynamics suggest that the arc instability when modifying the direction of welding (pulling and pushing) and that the polarity of HW was responsible for attracting or repelling the arc and, along with the feed rate, it can change cord geometry at a depth of penetration by 45% and dilution up to 25% compared to GMAW when the feed rate was 100%.

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