Search Results (84)

Globalization and the spread of technological innovations have made world markets and economies increasingly unified and conditioned by international trade, not only for sales markets but above all for the supply of raw materials necessary for the functioning of the production complex of each country. Alongside oil and gold, the main commodities traded include industrial metals, such as aluminum and copper, mineral products such as gas, electrical and electronic components, agricultural products, and precious metals. The conflict between Russia and Ukraine tested the unification of markets, given that these are countries with notable raw materials and are strongly dedicated to exports. This suggests that commodity prices were able to influence the stock markets, especially in the countries most closely linked to the two belligerents in terms of import-export. Given the importance of industrial metals in this period of energy transition, the aim of our study is to analyze whether Industrial Metals volatility affects G7 stock markets. To this end, the BEKK-GARCH model is used. The sample period spans from 3 January 2018 to 17 September 2024. The results show that lagged shocks and volatility significantly and positively influence the current conditional volatility of commodity and stock returns during all periods. In fact, past shocks inversely influence the current volatility of stock indices in periods when external events disrupt financial markets. The results show a non-linear and positive impact of commodity volatility on the implied volatility of the stock markets. The findings suggest that the war significantly affected stock prices and exacerbated volatility, so investors should diversify their portfolios to maximize returns and reduce risk differently in times of crisis, and a lack of diversification of raw materials is a risky factor for investors. Full article

Background: There is substantial evidence supporting the role of genetic alterations in chemically induced carcinogenesis. We analyzed the existing literature to gather data on genetic alterations linked to human carcinogens and their possible connection to genotoxic outcomes. The review emphasizes carcinogenic substances and occupational exposures identified as “carcinogenic to humans”. In particular, we searched for studies describing genotoxic alterations linked to agents and occupational exposures for which the International Agency for Research on Cancer has found sufficient evidence of an association with bladder cancer. Methods: The review was carried out in compliance with the PRISMA standards. A comprehensive search of the PubMed database was conducted to identify studies published through March 2024. Results: We identified 60 studies that evaluated genetic alterations for 16 carcinogenic agents and occupations (such as aluminum production, 4-aminobiphenyl, auramine production, benzidine, chlornaphazine, cyclophosphamide, firefighters, magenta production, 2-naphthylamine, opium consumption, ortho-toluidine, painters, the rubber manufacturing industry, Schistosoma haematobium infection, X-radiation, gamma-radiation) in healthy humans. Conclusions: The genotoxic effects of chemical agents in healthy individuals have been well studied and characterized. Additionally, this review presents numerous studies concerning occupational exposure but not exclusively. Genotoxicity assessments have mainly been conducted on biological materials such as blood, peripheral blood lymphocytes, urine, and buccal epithelial cells. The most frequently examined genotoxic effects were DNA damage, chromosomal abnormalities, and micronuclei. Standardized data to clearly define a dose–response relationship for predicting delayed health effects are still lacking. Full article

The integral welded panel represents a highly promising aircraft structural component, owing to its lightweight design and reduced connector requirements. However, the complexity of its welded structure results in the formation of cross-welded joints. This study systematically investigated the mechanical properties of the cross-welded joints through tensile tests across different welded regions, which were complemented by fracture morphology examination via scanning electron microscopy (SEM). The residual stress distribution was characterized using X-ray diffraction, while electron backscatter diffraction (EBSD) analysis was used to elucidate the relationship between residual stress and microstructure. Key findings revealed that the cross-welded zone exhibited lower yield strength and ductility than the single-welded zone, and the advancing heat-affected zone demonstrated superior tensile properties relative to the retreating side. Residual stress analysis showed that the cross-welded joint lacked the “double peak” profile characteristic and displayed lower maximum residual stress than the single-welded joint. EBSD analysis indicated significant grain elongation in the cross-welded zone due to mechanical forces during the welding process, resulting in higher dislocation density and deformation, corresponding with elevated residual stress levels. Full article

This study investigates the impact of modeling the aluminum (Al) metallization layer as an integrated part of the chip model, versus as an individual component, on the results of electrical–thermal analysis of power semiconductor packages using Finite Element Analysis (FEA), ANSYS 2024 R2. The results showed that modeling the aluminum metallization layer separately exhibited high consistency with actual thermal imaging data. Furthermore, based on these findings, we observed through simulations that the aluminum metallization layer plays a key role in improving the uniformity of current density and temperature distribution within the chip. Using the aluminum metallization layer model, we optimized the thickness, material, and design of the metallization layer, as well as the bonding wire material through the design of experiments (DOE) methodology. Under the optimized conditions, an optimal design is proposed to minimize the voltage–current ratio (V_DS/I_DS), maximum junction temperature, strain, and von Mises stress. This study systematically examines the influence of aluminum metallization layer modeling on FEA-based power semiconductor package simulations and is expected to serve as a valuable reference for future power device design utilizing finite element analysis. Full article

Italy ranks among the leading countries in photovoltaic (PV) adoption, having installed 6.80 GW of new PV capacity, bringing the total installed capacity to 37.09 GW in 2024. However, this widespread deployment also leads to a substantial amount of PV waste as systems reach the end of their lifespan. This study aims to estimate the volume of PV waste expected to be generated in Italy due to the decommissioning of end-of-life (EoL) PV panels and to explore landfill and recovery scenarios that could offer the most sustainable management strategies. The findings indicate that 4520 kilotonnes of PV waste will be produced in Italy between 2030 and 2050. Of this, a significant share consists of glass (2704.9 kilotonnes) and aluminum (762.1 kilotonnes). Additionally, Italy will produce 174.6 kt of landfill waste in 2036. In 2049 and 2050, the total composition recovery is predicted to reach 571 kt and 604.7 kt, respectively. To summarize, the main contributions of this work include (1) projections of the EoL of crystalline silicon PV waste by material quantity for 2050, (2) the economic value share of PV module materials based on waste estimates and recovery, and (3) the estimation of the EoL solar compositions generated by 2050. Full article

The main barriers faced by small-scale cocoa producers in Ecuador are the limited access to and the use of information technologies, which affects their efficiency in production and marketing. This study evaluated the impact of information behavior on the fertilization and marketing strategies of small cocoa farmers in two Ecuadorian provinces that have presented outstanding performance at the national level in order to identify the main factors that cause information gaps. For this purpose, a structured survey was conducted between May and June 2024 on 150 cocoa producers farming up to 10 hectares to collect demographic data and analyze their information-use patterns in relation to agricultural market strategies. The survey included five dimensions: information sources, information evaluation, informational, social and economic. In addition, soil chemical analyses were conducted in 50 plantations managed by the same farmers to determine the affinity between fertilization practices and the nutritional needs of the crop. The results indicated that farmers in Guayas showed a more developed information behavior, with a greater knowledge of their information needs and an active interest in collecting data on agricultural markets. In contrast, farmers in Los Ríos made less use of the media as a source of information, which limited their impact on social and economic aspects. In soil chemistry, both provinces presented favorable conditions for the crop; however, low nitrogen and potassium concentrations could affect yields. In Guayas, the analyses revealed averages of 0.34 cmol(+)/L aluminum, 3.03 cmol(+)/L magnesium and 0.33 cmol(+)/L potassium, values that mostly meet the nutritional standards for cocoa. In Los Rios, the analyses reflected average values of 0.68 ± 0.46 cmol(+)/L aluminum, 2.98 ± 1.13 cmol(+)/L magnesium and 0.34 ± 0.11 cmol(+)/L potassium. Based on the findings of this study, in order to improve the competitiveness of the sector, it is suggested to design accessible public policies and training programs oriented to the use of digital tools and sustainable practices that promote access to markets and optimize the production chain. Full article

The atmospheric corrosion behavior of type 2024, 5083, 6061, and 7075 aluminum alloys in the Antarctic environment was investigated by outdoor exposure tests and indoor characterization. After one year of exposure to the Antarctic atmosphere, significant differences in surface corrosion states were observed among the specimens. The results revealed that the corrosion rate of the 2024 aluminum alloy was the highest, reaching 14.5 g/(m²·year), while the 5083 aluminum alloy exhibited the lowest corrosion rate of 1.36 g/(m²·year). The corrosion products formed on the aluminum alloys exposed to the Antarctic environment were primarily composed of AlOOH and Al₂O₃. In the Antarctic atmosphere environment, the pits were dominated by a freezing–thawing cycle and salt deposition. The freezing–thawing cycle promotes the wedge effect of corrosion products at the grain boundary, resulting in exfoliation corrosion of high-strength aluminum alloys. Full article

In this study, the correlations between milling conditions—namely, the cutting tool feed direction relative to the rolling direction, the milling type, the coolant application, as well as the cutting speed—and the surface residual stress of a selected aluminum alloy (2024 T351) were investigated. Determining the type and magnitude of residual stress is of paramount importance as this stress is among the primary causes of post-machining strain of thin-walled components. On the basis of the experimental results, it was found that all factors analyzed significantly affect the residual stress state. Specifically, milling in the parallel direction induces lower residual tensile stress compared to milling in the perpendicular direction. Analogously, up-milling yields lower tensile residual stress than down-milling, and flood cooling leads to lower tensile residual stress than MQL. It was clearly confirmed that as cutting speed increases, tensile residual stress also increases, but only up to a certain threshold; once the high-speed cutting regime is reached, tensile residual stress begins to decrease. Consequently, the proper selection of milling parameters is a crucial consideration for optimizing machining processes and minimizing machining-induced residual stress. Full article

Small-scale impact welding may have several advantages over rivets: the strength can be higher, it can be applied right at the edges in lap joints, and it can be lighter and more easily installed if simple systems can be developed. Laser Impact Welding (LIW) is compact and simple, adapting the technologies of laser shock peening. It is limited in terms of the energy that can be delivered to the joint. Augmented Laser Impact Welding (ALIW) complements optical energy with a small volume of an exothermic detonable compound and has been shown to be an effective welding approach. The scope of this study is extended to build upon previous work by investigating varied augmentation chemistries and confinement layers, specifically borosilicate glass, sapphire, and water. The evaluation of these compositions involved the use of two aluminum alloys: Al 2024 and Al 6061. Photonic Doppler Velocimetry (PDV) was utilized to measure the flyer velocity and assess the detonation energy. The findings indicated that adding micro-air bubbles (GPN-3 scenario) to the original GPN-1 enhanced the flyer velocity by improving the sensitivity, which promoted gas release during detonation. Hence, employing 1 mm thick Al 2024 as a flyer with GPN-3 enhances the flyer velocity by 36.4% in comparison to GPN-1, thereby improving the feasibility of using 1 mm thick material as a flyer and ensuring a successful welded joint with the thickest flyer ever welded with laser impact welding. When comparing the confinement layers, sapphire provided slightly lower flyer velocities compared to borosilicate glass. However, due to its higher resistance to damage and fracture, sapphire is likely more suitable for industrial applications from an economic perspective. Furthermore, the lap shear tests and microstructural evaluations confirmed that GPN-3 provided higher detonation energy, as emphasized by the tendency of the interfacial waves to have a higher amplitude than the less pronounced waves of the original GPN-1. Consequently, this approach demonstrates the key characteristics of a practical process, being simple, cost-effective, and efficient. Full article

Objective: The aim of this systematic review was to evaluate the effectiveness and safety of various laser wavelengths for debonding orthodontic metal brackets compared to traditional plier-based methods. The primary outcomes assessed were enamel damage, pulp temperature changes, adhesive remnant index (ARI), and shear bond strength (SBS). Materials and Methods: In September 2024, an electronic search was performed across the PubMed, Web of Science (WoS), and Scopus databases, adhering to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and the PICO framework. The initial search yielded 453 records. After eliminating 256 duplicates, 197 unique records were left for screening, which ultimately led to the qualification of 8 articles that met the inclusion criteria for both qualitative and quantitative analyses. The risk of bias in the articles was assessed by two independent reviewers. Results: The included studies demonstrated that laser-assisted debonding generally resulted in less adhesive residue on the enamel surface compared to conventional methods, as evidenced by the reductions in ARI scores reported in two studies. Temperature increases during laser use varied depending on the laser type and power settings. The Nd:YAG (neodymium-yttrium, aluminum, garnet) laser was found to cause significant temperature rises, posing a potential risk to pulp tissue, while the Er:YAG (erbium—yttrium, aluminum, garnet) and Er,Cr:YSGG (erbium, chromium—yttrium, scandium, gallium, garnet) lasers produced only negligible increases in pulp temperature. SBS comparisons revealed no significant differences between the laser-assisted and traditional debonding methods. Additionally, diode lasers demonstrated the potential to minimize enamel damage, particularly when operated at lower power settings. Four publications were assessed as high quality (low risk of bias), and another four as moderate quality (average risk of bias). Conclusions: In conclusion, laser-assisted orthodontic metal bracket debonding, when conducted with appropriately calibrated parameters, is a safe method for preserving tooth tissue. However, its advantages appear to be minimal compared to conventional plier-based methods, highlighting the need for further research to justify its broader clinical application. Full article

Welding-induced residual stress has the capacity to significantly compromise the integrity of mechanical components. Its minimization therefore plays a critical role in the selection of process parameters during the welding process. Friction stir welding is a useful joining technique to weld many materials that are not amenable to the traditional welding techniques. Using a sequentially coupled thermomechanical three-dimensional finite element simulation, this work aimed to quantitatively evaluate the influence of the tool rotational and traverse speeds on the generation of residual stress in the friction stir welding of dissimilar aluminum alloys $\mathrm{AA}2024-\mathrm{T}3$ and $\mathrm{AA}5086-\mathrm{O}$. The model was validated using established experimental and numerical results. The procedure entailed an initial thermal analysis, the results of which were superposed on a mechanical model to determine the distribution of the residual stress across the welded alloy. The results showed that longitudinal residual stress was dominant as compared to lateral stress. It was also demonstrated that, although the tool rotational speed and the tool traverse speed both affected the post-weld temperature distribution and consequently the longitudinal residual stress, the influence of the former was more substantial. Furthermore, the peak values of the residual stress were found on the retreating side ($\mathrm{AA}5086-\mathrm{O}$), making it more critical for the selection of welding process parameters. Full article

The influence of temperature on the precipitation evolution in different zones of friction stir welded (FSW) heat-treatable aluminum alloys has been well investigated. However, the role of plastic deformation in affecting precipitation transformations remains less explored. To isolate the contribution of these factors and specifically assess the role of plastic deformation, an approach combining numerical and physical modeling techniques was used. Welding temperature cycles in the FSW weld zones calculated by means of a 3D finite element model were accurately reproduced using a Gleeble instrument. This approach was implemented under two scenarios such as the reproduction of the influence of temperature alone, and the combined effects of temperature and thermally induced plastic strain. The precipitation states and hardness obtained from these controlled experiments were compared to those observed in actual friction stir welds, providing a deeper understanding of the influence mechanisms at play. The results revealed that deformation significantly influences precipitation formation in the stir zone of both 2024 and 6082 alloys, with this effect extending to the heat-affected zone in the case of the 2024 alloy. Full article

This study presents a comparative analysis of the corrosion and mechanical properties of an Al-SiC composite and an AA 2024 aluminum alloy, focusing on their suitability for aeronautical applications. The Al-SiC composite was fabricated using advanced powder metallurgy techniques, incorporating a 20% volume of silicon carbide (SiC) particles, averaging 1.6 µm in size, to enhance its structural and electrochemical performance. Electrochemical evaluations in an aerated 3.5% NaCl solution revealed a significant improvement in the corrosion resistance of the Al-SiC composite. This enhancement is attributed to the cathodic nature of the SiC particles, which promote the formation of a protective aluminum oxide layer, reducing pitting corrosion and preserving the material’s structural integrity. In terms of the mechanical properties, the Al-SiC composite demonstrated a higher yield strength and ultimate tensile strength compared to the AA 2024 alloy. While it exhibited a slightly lower elongation at failure, the composite maintained a favorable balance between strength and ductility. Additionally, the composite showed a higher Young’s modulus indicating improved resistance to deformation under load. These findings underscore the potential of the Al-SiC composite for demanding aerospace applications, offering valuable insights into the development of materials capable of withstanding extreme operational environments. Full article

The growing demand for alkali metals (AMs), such as lithium, cesium, and rubidium, related to their wide application across various industries (e.g., electronics, medicine, aerospace, etc.) and the limited resources of their naturally occurring ores, has led to an increased interest in methods of their recovery from secondary sources (e.g., brines, wastewater, waste leachates). One of the dynamically developing research directions in the field of separation of AMs ions from various aqueous solutions is the search for novel, efficient, and “green” materials that could be used in adsorption processes, also on a larger industrial scale. This review concerns the latest achievements (mainly from 2023 to 2024) in the development of innovative adsorption materials (e.g., ion sieves, aluminum-based adsorbents, mineral adsorbents, composites, resins) for the separation of Li⁺, Cs⁺, and Rb⁺ ions from solutions, with particular emphasis on their most important advantages and limitations, as well as their potential impact on the environment. Full article

In this experiment, plasma-enhanced chemical vapor deposition technology was used to deposit diamond-like carbon thin films on the surface of a 2024 aluminum alloy. The effects of deposition temperature on the microstructure, carbon, silicon, and aluminum element distribution, and film substrate adhesion of diamond-like carbon thin films were studied using field emission scanning electron microscopy, energy-dispersive spectroscopy, XRD, scratch gauge, and ultra-depth-of-field microscopy. The results showed that with the increase in deposition temperature, the thickness of DLC film decreased from 8.72 μm to 5.37 μm, and the film bonded well with the substrate. There is a clear transition layer containing silicon elements between the DLC film and the aluminum alloy substrate. The transition layer is a solid solution formed by aluminum and silicon elements, which increases the bonding strength between the film and substrate. C-Si and C-C exist in the form of covalent bonds and undergo orbital hybridization, making the DLC film more stable. When the deposition temperature exceeds the aging temperature of a 2024 aluminum alloy, it will affect the properties of the aluminum alloy substrate. Therefore, the deposition temperature should be below the aging temperature of the 2024 aluminum alloy for coating. At a deposition temperature of 100 °C, the maximum membrane substrate bonding force is 14.45 N. When a continuous sound signal appears and the friction coefficient is the same as that of the substrate, the film is completely damaged. From the super-depth map of the scratch morphology, it can be seen that, at a deposition temperature of 100 °C, a small amount of thin film detachment appears around the scratch. Full article