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HELOISE LEAL MONTEIRO
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AVALIAÇÃO DA EFICÁCIA DOS ÓLEOS ESSENCIAIS DAS ESPECIES PIPER divaricatum E EUGENIA caryophyllus COMO INIBIDORES DE CORROSÃO EM AÇO CARBONO
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Data: 13/07/2023
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Mostrar Resumo
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This research reports the evaluation of essential oils (OEs) such as those from the plant Piper divaricatum and Clove (button) Eugenia caryophyllus, as green inhibitors of protection in metallic materials precisely in this work, carbon steel. Resistance tests were carried out in corrosive media such as 1M HCl and 3.5% NaCl, the concentrations used for both essential oils were 0.5g/L; 1g/L; 2g/L and 4g/L, for periods of time such as 24h and 7 days. The method used to evaluate the efficiency of the oils was gravimetric (weight loss). The Scanning Electron Microscopy technique of the field emission gun type (MEVFEG) was conducted to investigate the surface of the specimen, while its chemical composition was treated through Electron Dispersion Spectroscopy (EDS). In this work, several aspects were discussed, such as the efficiency in relation to the time the specimen is exposed to corrosive media and factors such as the adsorption isotherm of oils on the metal surface, in addition to studies of the corrosion rate of the specimens in the absence and presence of inhibitors and their relationship with the oil concentrations used. The studies indicated that the essential oils of Piper divaricatum and Clove (Eugenia caryophyllus) showed excellent results in an acid medium of up to 98.3% for the concentration of 2g/L of Piper divaricatum EO in 24h, and 89.5% for the concentration of 1g/L of Eugenia caryophyllus EO in 7 days. In the neutral medium, the highest percentages of progress were 61.1% for the concentration of 0.5g/L of the EO of Piper divaricatum in 24h, and 83.3% for the concentration of 1g/L of the EO of Eugenia caryophyllus in 24h. the isotherms of the oils followed the Langmuir adsorption model, where both oils adsorbed on the metal surface forming a monolayer, the best results of isotherms were for the acid medium, for the neutral medium due to the high variability of the data it was not possible to establish a consistent following. In view of the proposed results, it was possible to conclude that the essential oils of P. divaricatum and E. caryophyllus have the potential to be used as resistance inhibitors, mainly in the acid medium, thus providing new alternatives, in order to reduce the toxicity of this process in comparison to inhibitors already on the market.
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DHONATA SEBASTIAO CALDAS OLIVEIRA
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ABS/NTC NANOCOMPOSITE SYNTHESIS FOR ADDITIVE MANUFACTURING OF QUICK RESPONSE CODES AND THEIR APPLICATION IN CRYPTOGRAPHY RAMAN SPECTRAL
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Data: 12/07/2023
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Mostrar Resumo
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Due to the Fourth Industrial Revolution, also known as Industry 4.0, factories increasingly have systems dependent on the Internet and communication technologies, which guarantees them unprecedented efficiency, but makes them vulnerable to cyber attacks. For this reason, it is an increasingly relevant topic, with technologies such as blockchain and quantum cryptography based on physically unclonable functions (PUFs) presenting themselves as alternatives in this area. In this sense, this work presents the synthesis of poly(acrylonitrilebutadiene-styrene) (ABS) nanocomposites with 1 and 2 % respectively of carbon nanotubes (CNTs) mass for the 3D printing of the so-called NanoCodecs, which present Raman spectral signatures, classified as PUFs, which can be used as cryptographic keys generated by a code built in the Python programming language. For this, two solutions were prepared, the first with multi-walled CNTs functionalized with carboxylic acid in acetone, and the other with pure ABS pellets in this same solvent. After mixing these solutions and ultrasonic baths, the acetone was evaporated and ABS/NTC1%m/m and ABS/NTC2%m/m pellets were produced, which were used for the production of nanostructured filaments in an extruder. Then NanoCodecs as quick response code (QR code) and as round/square stamps were 3D printed. The electrical characterization of samples printed with nanostructured filaments showed a reduction in electrical resistance with an increase in the percentage by mass of CNTs. Despite this, the morphological characterization by Scanning Electron Microscopy showed that there is a low concentration of nanotubes on the surface of the samples, which indicates that they are dispersed throughout the volume of the samples. The vibrational characterization by Raman spectroscopy was used to identify the characteristics of pure materials, both ABS and NTCs, and compare with the Raman spectrum of the ABS/NTCs nanocomposite. As a result, there was an overlap of the vibrational modes of both materials, with emphasis on the shift to the right of the sub-band 𝐺𝑒𝑥𝑡 in 8 𝑐𝑚 −1, which indicates that the nanotubes are compressed in the polymeric matrix. Finally, using nanocomposites as PUFs, it was possible to generate keys from the main vibrational modes of these materials, the D, G and 2D bands of nanotubes and the bands named as 1001-PS and 2239-PAN of ABS. Therefore, the results obtained indicate that NanoCodecs can be used as elements of cybersecurity in Industry 4.0, through cryptographic keys generated by the interaction of the laser and the spectral vibration of the carbon nanotubes of the three-dimensional codes.
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LUCIANO JOSE BARBOSA QUARESMA
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DESENVOLVIMENTO DE SENSOR PIEZORRESISTIVO NANOESTRUTURADO IMPRESSO EM 3D
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Data: 05/07/2023
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Mostrar Resumo
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The emergence of smart factories based on Industry 4.0 increases the automation and optimization of industrial processes in production chains. In this context, the integration between physical and digital systems depends on intelligent sensors, with greater sensitivity and integrated by the Internet of Things (IoT). The literature indicates that piezoresistive sensors can be produced by additive manufacturing (AM) and nanostructured with carbon nanotubes (NTCs), which generate a nanoelectromechanical system (NEMS) after its dispersion in the material. Thus, this work presents the development of a low-cost piezoresistive nanoelectromechanical sensor, produced by applying layers of NTCs on poly(acrylonitrile-butadiene-styrene) (ABS) parts printed by fused deposition modeling (FDM), integrable to the Industry 4.0 via IoT through ESP32 microcontrollers. For this, a diaphragm-type sensor device with dimensions 17.8, 17.8 and 5.5 𝑚𝑚 was developed, whose sensor element deformation occurs by pressing a button. After MA printing of the device parts, carboxylic acid functionalized multi-walled CNTs (MWCNT-COOH) were dispersed by ultrasonic bath in a solution with a concentration of 1 𝑚𝑔/𝑚𝑙 of acetone and dimethylformamide, in a ratio of 1 ∶ 1 in volume, for coating the sensor elements in successive layers with an aerograph. After the deposition of five layers of CNTs on the polymeric substrate, measurements of electrical resistance obtained with a picoammeter showed the percolation of the material in the second layer, with initial values above 10 𝑇 Ω and final values below 100 𝑘 𝑂𝑚𝑒𝑔𝑎 after the fifth layer, which occurs by the formation of conduction channels originating from the random arrangement of CNTs on the ABS surface, as observed by Field Emission Scanning Electron Microscopy (FEG-SEM). After that, the electrical resistance was measured during pressure cycles with progressive load and with maximum load, in which the sensor elements presented an operating range of 139.97 ± 0.46 to 363.25 ± 0.39 𝑘𝑃 𝑎. In the first test, the minimum sensitivity of 0.1 % and maximum sensitivity of 1.16 %. In the second, the highest average sensitivity was 0.63 ± 0.04 % and the lowest average response and recovery times were 0.55 ± 0.29 𝑠 and 12.29 ± 1.44 𝑠, respectively. Raman spectroscopy showed the overlapping of the signals of each material, in particular the ABS band at 1447 𝑐𝑚 −1 which appears prominently between the NTCs 𝐷 and 𝐺 bands. Based on the piezoresistive response that the material presented from the NEMS generated by the deposition of NTCs on ABS, this concept of a load cell can be integrated into an ESP32 microcontroller board, making it an intelligent device with potential application in industrial systems. 4.0.
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KELLY COSTA ALVES
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Obtaining the pharmaceutical complex based on a double lamellar hydroxide (HDL) and Nimesulide
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Data: 28/06/2023
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Mostrar Resumo
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Nimesulide is a non-steroidal drug (NSAID) and presents biological activity based on the inhibition of the enzyme Cyclooxygenase-2 (COX-2) during the inflammation process. However, in the long term, the use of this drug can cause serious gastric disorders, in addition to high toxicity in normal tissues. To mitigate these possible effects, and thinking specifically for the Amazon region, other molecules with non-steroidal properties have been sought, from Amazonian oils. Among them are the fatty acids (saturated and unsaturated) that can be obtained from Amazonian oils. In addition, controlled drug release systems have been another alternative to mitigate side effects, in addition to increasing bioavailability, allowing effective dosages to remain in the bloodstream for a longer period of time, thus reducing the number of drug administrations to the patient. In these systems, the release rate of the active principle occurs from the matrix that transports it to its biological target. Within this context, there is the hybrid matrix of double hydroxide layered (HDL), obtained by the coprecipitation method. For these reasons, in this research, nimesulide was compared with the properties of some isolated saturated and unsaturated fatty acids. The comparison was based on molecular docking studies, using fatty acid molecules as potential COX-2 inhibitors. The best results found for fatty acids were intercalated in HDL as well as nimesulide, seeking to evaluate from its structural (DRX), vibrational (RAMAN) and morphological (SEM and SEM-FEG) characterizations the structural molecular mechanism of action of selected fatty acids as possible anti-inflammatory agents. The process of obtaining the compounds occurred by coprecipitation, constant pH close to 10, under the continuous flow of nitrogen, at 60 ºC, for 16 hours. The results demonstrate the direct influence of saturation on the intercalation of fatty acids in the HDL matrix. Among the complexes obtained, HDL-myristic acid presented a structural performance similar to that of HDL-nimesulide. And based on all the experimental and theoretical results obtained, three new and unprecedented complexes are proposed: HDL-Nimesulide, HDL-myristic acid and HDL linoleic acid as potential anti-inflammatory agents that need to be investigated in in vitro tests. Keywords: nimesulide, HDL, fatty acid, co-precipitation.
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LEANDRO JOSE SENA SANTOS
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DESENVOLVIMENTO DE TERMOSENSORES NANOESTRUTURADOS IMPRESSOS EM 3D
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Data: 26/06/2023
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Mostrar Resumo
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The market for temperature sensors and other related sensors has grown in recent years. It is estimated that it will have an annual growth of 11% per year between 2019 and 2026, and this has sparked interest in studies focusing on more portable nanosensors. Thus, this work presents the development of four sensors based on Poly (lactic acid) - PLA and Carbon Nanotubes - CNTs, produced by additive manufacturing and aimed at temperature monitoring, including negative temperatures. One of these sensors was developed only in PLA and the others were nanostructured by adding two different types of inks, containing CNTs. These were synthesized by 3D printing using Fused deposition modeling (FDM) technology, in addition to adopting different standards and methodologies for each one. Through morphological, vibrational, and electrical characterizations, the devices/sensors demonstrated thermoresistive and thermoelectric responses to the applied temperature variations. In this case, the morphology, as analyzed by electron microscopy and vibrational Raman spectroscopy obtained from the nanocomposite samples, showed the incorporation of CNTs in the PLA matrix, as well as their vibrational spectra obtained with characteristic signatures of the materials used. The manufactured devices have an active area of 15 cm2and presented a Seebeck coefficient at 1.33 µV/K under temperature gradients of 300K, in addition to presenting a maximum response of - 4.35± 0.15% for approximately 45 °C, for thermoresistive analysis. Thus, the developed devices exhibited the behavior of thermistors and thermocouples, which promote these to excellent temperature sensors.
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BIANCA MENDES ALMEIDA
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ESTUDO DAS PROPRIEDADES MECÂNICAS E MICROESTRUTURAIS DE MATERIAIS CIMENTÍCIOS GEOPOLIMÉRICOS PRODUZIDOS A PARTIR DE METACAULIM E ESCÓRIA DE ALTO FORNO
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Data: 21/06/2023
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Mostrar Resumo
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The environmental impacts caused by the production of Portland Cement point to the urgency of reducing the use of this binder mainly due to the CO2 emission and energy consumption that occur during its production process. In the search for alternative materials, geopolymer cement has shown promise, both in terms of mechanical performance and conservation of natural resources. These cements are obtained from natural raw materials containing aluminosilicates activated by an alkaline solution. In this work, geopolymeric cement paste, mortar and concrete were developed using metakaolin blast furnace slag and alkaline solution of sodium hydroxide and sodium silicate. The main objectives included evaluating the influence of blast furnace slag on the mechanical properties of geopolymer pastes, varying its addition in mass (30% to 60%), evaluating the influence of sand in geopolymer mortar varying its addition in the paste with better performance of 20% to 70%, and finally, the addition of gravel 0 in the concrete through the “rich” and “pilot” traits. The results showed that the paste reached a maximum compressive strength of 36.5 MPa with 35% slag in the matrix. This value rose to 41.15 MPa in the mortar with the incorporation of 40% sand. For concrete, the best result found was for the “rich” mix, which contained less crushed stone. The results of the concrete were compared with the CPV ARI Portland cement concrete by setting some dosing parameters such as binder consumption and water/binder ratio. Other properties investigated included setting time, slump, bending traction and microstructural analysis. The “rich” trait of geopolymeric concrete was superior to Portland by up to 21.16%, reaching a compressive strength of 41.8 MPa and better matrix/aggregate adhesion. Such characteristics make possible its application in civil works that demand materials that reach high resistance in the initial ages, precast industries and paving.
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KAMILA SINDY PINHEIRO DA CRUZ
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PRODUÇÃO DE AGREGADOS SINTÉTICOS PARA CONSTRUÇÃO CIVIL A PARTIR DE MATERIAIS GEOPOLIMÉRICOS
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Data: 20/06/2023
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Mostrar Resumo
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The civil construction industry is one of the sectors of the economy that consume the most natural resources, from the production of inputs to the execution of the work, which can significantly affect the environment and the quality of life of the population. Geopolymers are inorganic polymers with great ecological potential, produced from aluminosilicates and synthesized by alkaline solutions, providing the material with better mechanical resistance. Geopolymeric cement is a high-tech material developed using clay minerals, with characteristics such as durability, mechanical resistance, strong adhesion, heat resistance, in addition to being easily mixed and applied. The present study sought, through a correct proportion of the components that constitute the geopolymer, the production of a Geopolymeric Synthetic Aggregate (ASG), making variations with percentages of blast furnace slag and variations in the alkaline concentration of sodium hydroxide (NaOH). Soon after, physical tests were carried out on the powdered materials to verify the fineness index, loss on fire and moisture content of kaolin, metakaolin and blast furnace slag. The samples underwent characterization and the main analyzes involved in the process were: X-ray diffraction (DRX), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and EDS. A compression test was also carried out on the geopolymer synthetic aggregate specimen. The results of the compressive strength test indicated that the specimen with a percentage of 35% blast furnace slag and an alkaline concentration of sodium hydroxide at 10 molar presented better results. In the analysis of the microstructure of the paste, a dense morphology was observed, which gives the material high resistance to compression.
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LUIZA DE MARILAC PANTOJA FERREIRA
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DESENVOLVIMENTO DE LÍNGUA ELETRÔNICA NANOESTRUTURADA BASEADA EM BUCKYPAPER E SEU USO PARA AUTENTICAÇÃO DE BEBIDAS ETÍLICAS
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Data: 06/03/2023
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Mostrar Resumo
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The development of electronic gadgets has become of great relevance for the detection of fraud in beverages such as wine, as illegal practices involving the addition of exogenous substances such as alcohol and dilution with water pose risks to human health as well as economic impacts. Thus, in this study, Buckypapers (BPs) films were developed based on pure Multi-Walled Carbon Nanotubes (pure-MWCNTs) and functionalized with Carboxylic Acid (COOH-MWCNTs) deposited through vacuum filtration on cellulosic filter paper for application as an element sensor in the analysis of ethylic beverages based grapes and açaí (unadulterated and adulterated with 1.0, 2.5, 5.0, 7.5 and 10% distilled water and ethyl alcohol). The morphological characterization of BPs by Scanning Electron Microscopy indicates the formation of dispersed COOH-MWCNTSs agglomerates on the surface and between the cellulosic fibers of the paper, as well as poor adhesion and non-uniform deposition of highly agglomerated pure-MWCNTs. Electrical resistance measurements were performed as a function of time (R × t) using the two-tip method, at room temperature, adding the analytes to the surface of the sensor element samples using a micropipette. The analysis of the response obtained through normalized relative resistance curves demonstrates a different behavior for BP-COOH-MWCNTs, obtaining a positive variation in the presence of Port and Açaí wines adulterated with water and a negative variation for adulteration with ethyl alcohol. Such behaviors were not observed in the BP-pure-MWCNTs, showing that the responses originate from the polar interactions established between the COOH groups and the adulterant molecules added to the wines, culminating in pronounced performance parameters for the BPCOOH-MWCNTs (response maximum of 5.67 ± 1.82 for unadulterated açaí ethyl beverage and maximum response and recovery times of 37.33 min and 50.58 min for Port wine adulterated with 5.0 and 10% distilled water, respectively). Data processing by PCA showed the ability of BP-COOH-MWCNTs to discriminate and recognize analytes and adulterants, indicating its potential application as a chemoresistive sensor element of low cost, easy handling and real-time response in an “Internet of Things” (IoT) device composing a nanostructured “electronic tongue” for ethyl beverage authentication.
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AVENER GLEIDSON ANDRADE SANTOS
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CHARACTERIZATION OF TURURI FIBROUS TISSUE AND EVALUATION OF MECHANICAL AND THERMAL PROPERTIES OF POLYESTER MATRIX POLYMER COMPOSITES REINFORCED WITH TURURI FIBROUS TISSUE
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Data: 30/01/2023
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Mostrar Resumo
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In the last decades, the search for ecologically clean materials has become increasing, i.e., materials that are able to aggregate sustainable aspects and high mechanical performance. In the context of sustainability, the use of waste for the production of new materials has become frequent, because the incorporation of this waste can represent a solution for its environmentally correct disposal. The use of natural fibers in the production of new materials has increased a lot in recent years. The tururi fibrous tissue comes from the Ubuçu palm tree. The tissue is responsible for wrapping the fruits of the palm. Part of the fibrous tissue from the collection of the fruits is used in handicrafts and rudimentary activities such as covering houses. However, a large amount of this waste is discarded in inadequate places, thus generating environmental damage. In this context, the use of tururi fabric as a reinforcement agent in polymer matrix composites appears as a viable alternative for the sustainable disposal of this waste. The use of natural fibers as reinforcement in composites of polymeric matrix is already well consolidated, because some fibers have high mechanical performance and good thermal stability, two highly attractive properties in composite materials. The composites reinforced with natural fibers have a wide field of application, and can be used in civil construction, aerospace, and automotive industries, among others. In this context, the present study aims to characterize the tururi fibrous tissue by means of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR), as well as to determine physical properties such as weight, specific mass and moisture content of the tissue. Consequently, to evaluate the mechanical behavior of polyester matrix composites reinforced with tururi fibrous fabric. The composites will be made with 2.5, 5.0 and 7.5 % in mass of fibrous reinforcement. After the confection of the composites these will be tested in traction, flexion and Charpy impact. Moreover, the morphology of the composites will be analyzed by scanning electron microscopy at the point of fractures of the aforementioned tests, in order to verify the adhesion between matrix and reinforcement and understand the type of fracture. The mechanical tests will be performed in order to verify the possibilities of application of these composites in automotive, ballistic and civil construction areas
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