Resumen en Inglés:

Abstract Brazil is a country with the second-highest production of iron ore in the world. As a consequence, tons of iron ore tailings (IOT) are generated, which constitutes an environmental liability. In this context, the present research aims to evaluate the potential for using IOT as raw material for making bricks or tiles, employing for example, the mixture soil-cement-sand-IOT. The objective is to determine mechanical parameters for this type of mixture to support future numerical analyses in a 3D environment in order to evaluate the potential of applying the mixture to the aforementioned elements. Therefore, a mixture of residual soil, IOT, sand and cement was prepared, and the Simple Compressive Strength Test was run to obtain the parameters of interest; additionally, analytical methodology obtained in literature was applied to determine other parameters of interest. After the experimental stage, computational simulations were conducted to verify whether the mechanical parameters obtained in laboratory tests and analytically are representative of the mechanical properties of the mixtures. The verification was carried out by comparing the results from simple compression tests with the results obtained via simulation of this test using the finite element method. Analyses were conducted using Plaxis 2D software. It was verified that the mechanical parameters obtained via simple compression tests and analytical equations are representative of the mechanical behavior of the mixtures, and therefore, such parameters can be used for numerical simulations of various components of civil construction. Thus, the mixture has potential for use, including other geometries, which also give this waste some value as a raw material in civil construction.

Resumen en Inglés:

Abstract In this article presents a programming routine that was developed based on the Python language for the design of non-slender web steel beams having mono symmetrical and doubly symmetrical sections, with welded and rolled profiles, and composite steel and concrete beams, in accordance with NBR8800:2008 for various loads. A Genetic Algorithm routine was incorporated into the code in order to perform discrete parametric optimization to obtain the best profile from an extensive list of commercial profiles for a given load. Important parameters, such as bending inertia, weight, elastic modulus, radius of gyration and simple bending were used in a weighting function, consisting of a linear combination of these parameters and weights. After determining the optimum weights of the weighting function via the PyGad genetic algorithm, the optimized profile was found to meet the constraints prescribed by the NBR8800:2008 standard. Between the serviceability limit states, vibration frequency checks were inserted into the optimization problem. Finally, following the optimization process, the designed and optimized elements will be checked for dynamic susceptibility through modal analysis. After checking the design constraints, according to NBR8800:2008, various analyses can be carried out with the selected beam, such as price, weight ratio, boundary condition, use and even a parallel study between various types of beams and profiles of different models. In this way, seven different beam models were made for comparison, showing that the program can be effective for future studies or even for day-to-day practice.

Resumen en Inglés:

Abstract Rockfill material is widely used in the construction of rockfill dam bodies, protective slope linings, and drainage systems, as well as in the stabilization of natural slopes. This material possesses high mechanical strength, excellent durability against erosive processes, and is economically viable for geotechnical solutions. Estimating resistance and elastoplastic parameters often relies on literature data, since full-scale tests are challenging and costly. This article investigates the shear stress (τ) versus relative displacement (δ) behavior and the friction angle of failure (ϕ) in large-scale shear tests on rockfill samples with varying mean diameters (D50). It also simulates τ versus δ behavior using the mathematical models of Clough and Duncan (1971) and Teixeira (2003) for comparison. The analyses showed that the hyperbolic model by Clough and Duncan (1971) and Teixeira (2003), when properly calibrated, can accurately simulate the mechanical behavior of the rockfill.

Resumen en Inglés:

Abstract The performance of asphalt pavements is influenced by environmental conditions. Due to the smaller spatial coverage and the lack of data from ground-based meteorological stations in some locations, especially in underdeveloped countries, climate data from the NASA POWER reanalysis have great potential for use in pavement projects. However, their use requires designers to have some knowledge of climatology and/or data processing. Therefore, the objective of this article is to develop an online platform to access, process and download the climate data required for use in pavement design, in formats suitable for use in different models, considering the following hourly data: air temperature, dew point temperature, wind speed, shortwave solar radiation, percentage of sunshine, precipitation and relative humidity. To achieve the proposed objective, a platform was developed in the R programming language, hosted on shinyapps.io and using the nasapower package. The tool accesses the NASA POWER reanalysis data, processes it, makes the file available for download in Excel format, and can be used anywhere in the world. In addition, the platform summarizes the characteristics of climate data through violin plots, enabling critical analysis and a better understanding of the local climate by pavement designers. The developed tool is presented, and an example of its use is demonstrated and can be accessed at https://climapav.shinyapps.io/nasapowerdata/.

Resumen en Inglés:

Abstract Bioactive glass-ceramics are attractive for medicine and have been widely investigated. A growing number of studies have shown that bone tissue regeneration can be stimulated by bioactive glasses with different chemical compositions. In this way, glasses from the LZS system (Li2O-ZrO2-SiO2) have interesting mechanical, electrical, and thermal properties. However, they have not been studied for bone regeneration yet. In these materials, the presence of lithium as a bioactive ion can accelerate the deposition of hydroxyapatite, which represents bone regeneration. The bioactivity of the LZS glass-ceramic system has been proven. In this context, this research aims to investigate the bioactivity of glass-ceramic composites of the LZS system and tricalcium phosphate (TCP). To this end, the thermal properties of the raw materials were analyzed. Different compositions of LZS with TCP were prepared and thermally characterized. They were then treated at 800 °C and 900 °C and characterized in density, porosity, structure, and microstructure. The compacts were submerged in simulated body fluid (SBF) for different periods. Structural and microstructural analyses proved their bioactivity. Some samples were subjected to degradation tests by immersion in TRIS-HCl, quantifying the release of Li+ and Ca+. The cytotoxicity test was performed using glass-ceramics in direct contact with mesenchymal stem/stromal cells (SC), isolated from exfoliated human deciduous teeth. The results show that it was possible to produce bioactive glass-ceramics from LZS, as evidenced by the formation of new calcium phosphate structures, such as hydroxyapatite, on the surface of the samples after exposure to SBF. The SC viability test indicated that the materials were not cytotoxic at 0.25, 0.5, and 1.0 mg/ml. The glass-ceramic system under study is promising for medicinal applications in bone regeneration.

Resumen en Inglés:

Abstract The global commercial drone market is experiencing rapid growth, particularly in precision agriculture applications such as crop spraying. This market is projected to expand at an 8.3% compound annual growth rate (CAGR), contributing to an overall drone market value of approximately $55.8 billion by 2030. Agricultural drones are made of various materials including electronic waste components such as circuit boards, connectors, and pins, containing significant amounts of gold. While gold cyanidation is the primary method for gold extraction, there is a growing interest in more environmentally friendly alternatives. This study focuses on extracting gold from pins using thiourea-based leaching with temperature variation and ultrasound agitation, comparing it to conventional cyanide processes. The process begins with the X-ray fluorescence analysis of drone components to detect gold. The gold concentration in pins is measured through aqua regia digestion (1:25 ratio, 70°C, 2 h). Cyanide leaching is conducted at 25°C for 2 h at pH 14, with a 1:25 mass ratio, while Thiourea leaching is performed at a 1:10 ratio for 2 h and pH 1, under different conditions: varying temperature and ultrasonic agitation. Cyanide digestion shows about 83 ppm of gold, setting a standard recovery benchmark of 100%. In contrast, aqua regia yields 66.8%. The thiourea leaching's efficiency, influenced by temperature and agitation, sees its highest gold recovery at 43.19% of the cyanide standard, with ultrasonic agitation, although overall performance is below cyanide yields. Further research is needed to enhance gold recovery through thiourea based leaching, focusing on optimizing the temperature parameters and leaching conditions.

Resumen en Inglés:

Abstract The corrosion behavior of wire-arc additive manufactured (WAAM) and wrought high-strength low-alloy steel (HSLA) are studied. The submerged arc is used in this study because the deposition rate is high in comparison with other processes. A corrosion resistance evaluation was performed by using open circuit potential measurements, and electrochemical impedance spectroscopy (EIS) analysis, in an aqueous solution of NaCl 3.5 wt.%. Samples extracted from the upper, intermediate and lower region of the part manufactured by WAAM, in addition to the substrate, were evaluated. The bottom region of the WAAM sample showed the highest impedance modulus (2356 Ω.cm2) and the highest phase angle (50°), indicating its highest corrosion resistance in the saline medium. The bottom region of the sample showed the lowest hardness of 214-219 HV. This study demonstrates that it is possible to use a lower-cost HSLA steel in a WAAM production process, which is much faster to manufacture, in a corrosive environment.

Resumen en Inglés:

Abstract Environmental pollution is a worldwide problem. The increasing of irregular mining, and in industrial activities in the secondary sector, has also contributed to triggering these impacts in the Amazon. The dumping of waste from these industries containing a high concentration of heavy metals and dyes in effluents ends up altering the characteristics of the rivers in the region. Thus, the development of removers of these pollutants, derived from tailings, stand out in the treatment of these wastewaters. The goal of this study was to carry out new removal tests of the dyes methylene blue and methyl orange by an activated sodium vermiculite and heavy metals Cr+6, Mn+7 and Cu+2 by a LDH Shigaite-type phase. The removal performance was quantified by UV-visible spectrophotometry. Activated sodium vermiculite removed 99% of methylene blue and was not active for methyl orange. LDH removed 97% of Cr+6 and 100% of Mn+7, with no significant results for Cu+2.

Resumen en Inglés:

Abstract An analysis of existing flow technologies for use of cargo cableways to transport ore in mountainous deposits was carried out. Technical and economic calculations of the main indicators of ore transportation technologies for the use of a cargo cableway were carried out for the mountainous relief of the Jeruy gold deposit. A technical and economic comparison of technologies for transporting ore by truck and using a cargo cableway was carried out. The advantage of cargo cableways compared to automobile transportation is shown, especially in the conditions of difficult rugged mountainous terrain typical of the Jeruy deposit. As a result of enlarged calculations, the feasibility of using a cargo cableways in the conditions of the Jeruy gold deposit was substantiated for ore moving to the gold recovery plant (GRP), which will increase the economic indicators of the enterprise and improve the environmental situation at the mine due to a sharp harmful emission reduction from motor transport, and also increase the safety of mining operations at the mine.

Resumen en Inglés:

Abstract Oil exploration is complex and very expensive, presenting long-term returns and considerable risks of accidents. Saving time is the guideline of any optimization method to reduce drilling costs and CO2 emissions. Highly variable performances are found in any oilfield, even in similar depth ranges, due to multiple interactions between the many factors involved in the drilling operations. Understanding such gaps is complex, as different technologies and levels of energy are used in each bit run along an exploration campaign, affecting in different ways their performances. The objective of the methodology presented in this article is to provide tools to identify which are the factors and how they affect the productive time used to drill oilwells, allowing to measure the contributions of each factor in increasing the efficiency of the drilling operations. A case study analyzes a 35-year exploratory campaign offshore Brazil, where data of the 109 wells drilled in an oilfield is used to benchmark different performances, demonstrating the advantages of the methodology in oilwell planning and in finding the paths for reducing drilling costs and CO2 emissions. As drilling for O&G, CCUS and geothermal wells is expected to continue yet for decades, the learnings and the economic benefits for the operators will extended in the long terms to the whole society.