Da Silva

Abstract There is a growing need to evaluate the agreement between the field methods and integrate artificial intelligence (AI) using two-dimensional (2D) photos for enhanced real-world analysis.

Effects of the Combination of Chemical Pretreatments and Dry Grinding of the Arundo donax L. Plant

In this research, poly(lactic acid) (PLA) nanocomposites with multi-walled carbon nanotubes (MWCNT) were produced by extrusion, injection, and compression molding, focusing on electromagnetic shielding. Various amounts of carbon nanotubes (MWCNTs) were tested in PLA matrix, specifically ranging from 1 to 4 parts per hundred resin (phr). The resulting nanocomposites were analyzed before and after undergoing annealing heat treatment. It was observed that as the MWCNT content increased, the melt flow index of PLA decreased. This reduction indicates that the nanotubes were effectively accommodated into the PLA chain. The PLA/MWCNT (2 phr) formulation presented the greatest balance of properties, with potential for electromagnetic shielding application. Scanning electron microscopy (SEM) demonstrated that incorporating 2 phr of carbon nanotubes in PLA promoted good distribution, favoring high electrical conductivity and electromagnetic shielding between 20–22 dB (8.2–18 GHz), corresponding to approximately 99% attenuation. Furthermore, its properties, such as elastic modulus (3156 MPa), tensile strength (65.1 MPa), hardness (77.8 Shore D), and heat deflection temperature (55.3 °C), increased compared to pure PLA. After annealing, the PLA/MWCNT (2 phr) nanocomposite underwent a molecular reordering, resulting in an increased crystalline fraction, as confirmed by X-ray diffraction (XRD). However, the electrical conductivity maintained the same order of magnitude, while the electromagnetic shielding varied from 19.7 to 20 dB. The results indicate that these nanocomposites are promising for electromagnetic shielding applications and can be manufactured in the molten state.

Lignin, a renewable and widely available biopolymer, has been explored as an additive in polyolefins to develop high value-added materials. However, its low compatibility with polymers like polypropylene (PP) often causes poor particle dispersion and compromised mechanical properties. Esterification has proven effective in enhancing lignin-polyolefin interactions. This study evaluated the incorporation of kraft lignin (KL) and maleic anhydride-modified kraft lignin (MAKL) into PP, focusing on lignin dispersion and the blends' thermal, mechanical, and viscoelastic properties. Thermal analyses showed that MAKL reduced PP crystallinity, indicating improved compatibility, supported by micrographs showing more uniform particle dispersion. Mechanically, low MAKL concentrations maintained yield strength similar to neat PP, while 5 wt% MAKL increased impact strength by up to 148%. This improvement was attributed to enhanced interfacial interaction, reduced crystallinity, and better energy dissipation. The findings demonstrate that esterification of lignin with maleic anhydride effectively overcomes compatibility limitations with PP, leading to significant gains in mechanical and viscoelastic properties. This work advances lignin's sustainable use in polymer blends, emphasizing its potential as a renewable alternative in material development.

Salinity is a significant challenge for agriculture in semi-arid regions, affecting the growth and productivity of plants like Tropaeolum majus (nasturtium), which is valued for its ornamental, medicinal, and food uses. Salt stress disrupts the plant’s biochemical, physiological, and anatomical processes, limiting its development. This study investigates the potential of proline as an osmoprotectant to mitigate the effects of salt stress on nasturtium’s growth and physiology. A completely randomized factorial design was employed, testing five levels of electrical conductivity (0.0, 1.50, 3.00, 4.5, 6.5 dS m−1) and four proline concentrations (0.0, 5.00, 10.0, 15.0 mM) with six replicates. The results showed that proline application, particularly at 15.0 mM, enhanced growth parameters such as leaf number, stem diameter, and root length. At moderate salinity (3.0 dS m−1), proline significantly improved gas exchange, increasing net photosynthesis, transpiration, and stomatal conductance. Additionally, proline reduced the negative impact of salt stress on the fresh mass of leaves, stems, and roots, and increased both the mass and number of flowers. Proline also elevated the levels of total phenolic compounds and vitamin C while reducing soluble sugars, particularly under moderate salt stress (4.75 dS m−1). Overall, applying 15.0 mM proline shows promise for enhancing the biomass accumulation, flower production, and overall quality of nasturtium under saline conditions.

An experimental study was conducted to analyze temperature evolution during very high cycle fatigue tests. The temperature–number of cycles (T–N) curve is typically divided into three phases: Phase I—a rapid temperature increases at the start of the test, Phase II—temperature stabilization, and Phase III—a sharp temperature rise at the test’s end, coinciding with specimen fracture. The high frequencies used in ultrasonic fatigue testing can induce self-heating in specimens, but the thermal effects are not yet fully understood. Temperature is known to influence the fatigue performance of materials. To explore this, specimens were subjected to varying stress levels and intermittent loading conditions while monitoring temperature evolution using infrared thermography. The T–N curves were obtained, and S–N curves were constructed for specimens tested at room temperature. All tests were performed under fully reversed loading conditions. The experimental data were used to evaluate models commonly applied in conventional fatigue testing. Additionally, the temperature gradient at the beginning of the ultrasonic fatigue test and the heat dissipation per cycle were estimated and analyzed as potential fatigue damage parameters. These findings indicate that parameters derived from the T–N curve have significant potential for predicting very high cycle fatigue life.

Aquaculture practices often expose fish to several stressors, which may activate the stress system, decreasing welfare status and negatively affecting several physiological processes, such as growth, reproduction, or immune response [...]

Open Access Communication by Liziane C. M. da Silva Liziane C. M. da Silva SciProfiles Scilit Preprints.org

Universidade Eduardo Mondlane, 3453 Avenida Julius Nyerere, Maputo 257, Mozambique

This study used a ground-penetrating radar (GPR) to characterize the archaeological environment of site GO-Ja-02 in Serranópolis, Goiás, Brazil. In the Serranópolis region, there are records of numerous human burials in archaeological sites located in predominantly sandy soils. Thus, this study proposed the application of a ground-penetrating radar to locate buried archaeological structures. Using a 400 MHz shielded antenna, the 2D data revealed distinct reflection patterns associated with subsurface elements such as rock blocks, roots, and rock surfaces, which were correlated with the anomalies observed in the depth slices of the generated pseudo-3D block. A ranking methodology was developed based on the archaeological context of the area and was used to indicate priority excavation areas. The results provided an understanding of the site's archaeological environment, allowing for prior knowledge of areas to be excavated. The non-invasive GPR approach enabled a detailed investigation without disturbing the site, aiding in decision-making for the archaeological team. Furthermore, this study establishes a methodological foundation for future investigations, demonstrating the effectiveness of integrating advanced technologies into archaeological research.