Search Results (209)

The physicochemical processes that occur during selective transfer in the contact area of a bronze/steel friction pair lubricated with glycerin are experimentally studied by the polarization method to observe how they influence the tribological properties (friction and wear) of the pair. The proposed method allows for the study of tribochemical transformations of glycerin and the friction pair materials during the work process with selective transfer. The analysis of the experimental results allows for the establishment of the conditions for a stable and stationary selective transfer during the operation of the bronze/steel pair, by friction, at which the friction coefficient (COF) values and wear are low. This was achieved by implementing continuous lubrication with fresh glycerin in the contact area, choosing the optimal flow rate, and maintaining an optimal ratio between glycerin and the chemical transformation products, within well-established limits, to avoid undesirable consequences. Acrolein, as a product of chemical transformation (resulting from the catalytic dehydration of glycerin), is the most important for the initiation and stability of the selective transfer, and as the main reaction product, also represents a pathway of regeneration. Thus, it was found that the friction relative moments and the acrolein concentration presented conclusive/specific results at loads of 4–15 MPa and a sliding speed of 0.3 m/s. The optimum lubricant entry speed is 15–30 mg/min, for a minimum COF and reduced wear (about 0.028–0.03 at relatively high operating temperatures (45 and 60 °C)), and at low temperatures (30 °C) the minimum COF is about 0.038, but the lubricant inlet entry speed increases considerably, by around 1000 mg/min. Therefore, this paper aims to demonstrate the possibility of moving to another stage of practical use of a friction pair (with greatly improved tribological properties) that operates with selective transfer, much different from the ones still present, using a lubricant with special properties (glycerin). The research method used (polarization) highlights the physicochemical properties, tribochemical transformations of the lubricant, and the friction pair materials present in the contact area, for the understanding, maintenance, and stability of selective transfer, based on experiments, as a novelty compared to other studies. Full article

Background/Objectives: Knee osteoarthritis is one of the most significant diseases globally and in Portugal. Despite the availability of international guidelines, there is a lack of tailored, evidence-based recommendations specifically for Portuguese physiotherapists to manage their knee osteoarthritis patients with non-pharmacological and non-surgical interventions. This study aimed to develop a clinical practice guideline that integrates the latest international evidence with local clinical practice data to enhance patient outcomes. Methods: To achieve the objective, a comprehensive search was conducted in November 2024 across major health-related databases, to identify robust and recent evidence regarding the efficacy of non-pharmacological and non-surgical interventions, as well as their usage in the national context. Two key sources were identified: An umbrella and a mixed-methods study. Data from both sources were independently reviewed and integrated through a comparative analysis to identify interventions with robust scientific support and high local acceptability. Recommendations were then formulated and categorized into gold (strong), silver (moderate), and bronze (weak) levels based on evidence quality and clinical relevance. A decision-making flowchart was developed to support guideline implementation and clinical usage. Results: The integrated analysis identified three gold-level interventions, namely Nutrition/Weight Loss, Resistance Exercise, and Self-care/Education. Five silver-level recommendations were Aerobic Exercise, Balneology/Spa, Extracorporeal Shockwave Therapy, Electrical Stimulation, and Manual Therapy. Similarly, five bronze-level recommendations comprised Kinesio Taping, Stretching, Ultrasound Therapy, Thermal Agents, and Walking Aids. Conclusions: This clinical practice guideline provides a context-specific, evidence-based framework for Portuguese physiotherapists managing knee osteoarthritis. By bridging international evidence with local clinical practice, the guideline aims to facilitate optimal patient care and inform future research and guideline updates. Full article

The possibility of collecting new archaeological elements useful in reconstructing the dynamics of population, production and commercial activities in the Bronze Age at the edge of the central-southern Venice Lagoon was provided between 2023 and 2024 thanks to an intervention of rescue archaeology planned during some water restoration works in the Giare–Mira area. Three small excavations revealed, approximately one meter below the current surface and covered by alluvial sediments, a rather complex palimpsest dated to the late Recent and the early Final Bronze Age. Three large circular pits containing exclusively purified grey/blue clay and very rare inclusions of vegetable fibres, and many large, fired clay vessels’ bases, walls and rims clustered in concentrated assemblages and random deposits point to potential on-site production. Two pyro-technological structures, one characterised by a sub-circular combustion chamber and a long inlet channel/praefurnium, and the second one with a sub-rectangular shape with arched niches along its southern side, complete the exceptional context here discovered. To analyse the relationship between the site and the natural sedimentary succession and to evaluate the possible extension of this site, three electrical resistivity tomography (ERT) and low-frequency electromagnetic (FDEM) measurements were collected. Several manual core drillings associated with remote sensing integrated the geophysical data in the analysis of the geomorphological evolution of this area, clearly related to different phases of fluvial activity, in a framework of continuous relative sea level rise. The typology and chronology of the archaeological structures and materials, currently undergoing further analyses, support the interpretation of the site as a late Recent/early Final Bronze Age productive site. Geophysical and geomorphological data provide information on the palaeoenvironmental setting, suggesting that the site was located on a fine-grained, stable alluvial plain at a distance of a few kilometres from the lagoon shore to the south-east and the course of the Brenta River to the north. The archaeological site was buried by fine-grained floodplain deposits attributed to the Brenta River. The good preservation of the archaeological structures buried by fluvial sediments suggests that the site was abandoned soon before sedimentation started. Full article

Olympic women’s judo has increased in complexity and competitiveness, demanding detailed tactical analysis. This observational study aimed to examine the relationship between the results of combats (Wazari [half point] vs. Ippon [full point]) and the techniques used in women’s judo combats in the Rio 2016 and Tokyo 2020 Olympic Games. A significant association was found between technique type and contest outcome (χ² = 40.004, df = 6, p < 0.001): Nage Waza (throwing techniques) produced 92.3% of Wazari, whereas Katame Waza (groundwork techniques) accounted for 61.1% of Ippon. Subgroup analysis confirmed these relationships (χ² = 17.217, df = 6, p = 0.009; Cramer’s V = 0.745), with Ashiwaza (foot/leg techniques) dominating Wazari. Uchimata was the most frequently used technique in the repechage (20%), bronze medal (22.6%), and final (23.1%) matches. In lightweights, Katame Waza dominated Ippon in finals (53.8%, χ² = 4.000, p = 0.046), while Nage Waza secured all Wazari. Middleweights also showed strong associations (χ² = 14.745, df = 1, p < 0.001; 93.9% of Wazari by Nage Waza). Although no significant association was found for heavyweights (χ² = 7.535, df = 1, p = 0.095), Katame Waza prevailed in Ippon (69.2%). These findings provide a tactical framework for tailoring technique-specific training by weight category and tournament phase to optimize outcomes in elite female judo. Full article

Nickel aluminum bronze (NAB) and manganese aluminum bronze (MAB) are widely used in propulsion and seawater handling systems in naval platforms due to their attractive combination of mechanical strength, toughness, and very low susceptibility to marine corrosion. Nevertheless, it is well known that they can suffer from selective phase corrosion and erosion–corrosion, primarily caused by cavitation and sand erosion. Both alloys have a multiphase microstructure that governs their mechanical and chemical behavior. The tribocorrosion behavior of cast NAB and MAB alloys was studied in artificial seawater to analyze the effect on microstructure. The microstructure and nanohardness were evaluated and correlated with tribocorrosion test results conducted under two different loads (10 and 40 N) in a unidirectional sliding mode using a 1 M NaCl solution as the electrolyte. A significant increase in the corrosion rate due to the wear effect was observed in both alloys. MAB exhibited a slightly better tribocorrosion performance than NAB, which was attributed to significant differences in the shape, distribution, and size of the intermetallic kappa phases—rich in iron, aluminum, and nickel—within the microstructure. Pitting corrosion was observed in NAB, while selective corrosion of kappa phases occurred in MAB, highlighting the role of the protective layer in the tribocorrosion behavior of both alloys. These findings were supported by post-test solution analysis using ICP-AES and corrosion product characterization by EDX. A synergistic effect between wear and corrosion was confirmed for both alloys, as erosion removes the protective layer, exposing fresh material to continuous friction and favoring a progressive material loss over time. The practical impact of this study lies in improving the control and design of highly alloyed bronze microstructures under in-service corrosion–erosion conditions. Full article

This study proposes a dual-statistical and gradient-based framework to evaluate the machinability of five engineering alloys under CNC turning. Cutting force and surface deformation were measured across five machining zones. Finite difference-based gradients revealed spatial variations in material response. Stainless Steel 304 showed the highest cutting force (328 N), while Aluminum 6061 had the highest deformation (0.0164 mm). Carbon Steel 1020 exhibited the highest force-to-deformation efficiency (>97,000 N/mm). Arithmetic and harmonic means highlighted statistical sensitivities, while principal component analysis (PCA) identified clustering among materials and reduced dimensionality. A composite machinability score, integrating stiffness variation, efficiency gradients, and multivariate features, ranked Aluminum 6061 highest, followed by Brass C26000 and Bronze C51000. This methodology enables interpretable benchmarking and informed material selection in precision manufacturing. Full article

Attaining dimensional accuracy in CNC-machined parts is essential for high-precision manufacturing, especially when working with materials that exhibit varying mechanical and thermal characteristics. This research provides a thorough experimental comparison of manual and automated metrological systems, specifically the Digital Vernier Caliper (DVC) and Coordinate Measuring Machine (CMM), as applied to five different engineering alloys through five progressively machined axial zones. The study assesses absolute error, relative error, standard deviation, and measurement repeatability, factoring in material hardness, thermal conductivity, and surface changes due to machining. The results indicate that DVC performance is significantly affected by operator input and surface irregularities, with standard deviations reaching 0.03333 mm for Bronze C51000 and relative errors surpassing 1.02% in the initial zones. Although DVC occasionally showed lower absolute errors (e.g., 0.206 mm for Aluminum 6061), these advantages were countered by greater uncertainty and poor repeatability. In comparison, CMM demonstrated enhanced precision and consistency across all materials, with standard deviations below 0.0035 mm and relative errors being neatly within the 0.005–0.015% range, even with challenging alloys like Stainless Steel 304. Furthermore, a Principal Component Analysis (PCA) was conducted to identify underlying measurement–property relationships. The PCA highlighted clear groupings based on sensitivity to error in manual versus automated methods, facilitating predictive classification of materials according to their metrological reliability. The introduction of multivariate modeling also establishes a new framework for intelligent metrology selection based on material characteristics and machining responses. These results advocate for using CMM in applications requiring precise tolerances in the aerospace, biomedical, and high-end tooling sectors, while suggesting that DVC can serve as an auxiliary tool for less critical evaluations. This study provides practical recommendations for aligning measurement techniques with Industry 4.0’s needs for accuracy, reliability, and data-driven quality assurance. Full article

This paper presents a study on optimising self-brazing powder mixtures for powder metallurgy diamond tools, specifically focusing on wire saws used in cutting natural stone. The research aimed to understand the relationship between the chemical composition of powder mixtures and the hardness of the sintered matrix. The experimental process involved the use of various commercially available powders, including carbonyl iron, carbonyl nickel, atomised bronze, atomised copper, and ferrophosphorus. The samples made of different powder mixtures were compacted and sintered and then characterised by dimensional change, density, porosity, and hardness. The obtained results were statistically analysed using an analysis of variance (ANOVA) tool to create linear regression models that relate the material properties to their chemical composition. The investigated materials exhibited excellent sintering behaviour and very low porosity, which are beneficial for diamond retention. Very good sinterability of powder mixtures can be achieved by tin bronze addition, which provides a sufficient content of the liquid phase and promotes the shrinkage during sintering. Statistical analysis revealed that hardness was primarily affected by phosphorous content, with nickel having a lesser but still significant impact. The statistical model can predict the hardness of the matrix based on its chemical composition. This model, with a determination coefficient of approximately 80%, can be valuable for developing new metal matrices for diamond-impregnated tools, particularly for wire saw beads production. Full article

This research presents a methodological approach combining UAV-LiDAR technology and SfM photogrammetry for the comprehensive documentation and analysis of O Corro dos Mouros, a Bronze-to-Iron Age archaeological site in the northwest of the Iberian Peninsula. The study evaluates both the capabilities and limitations of this integrated approach, focusing on a recently identified Roda-type structure, characterised by circular stone architecture and funerary-ritual functionality, dating between the 15th and 3rd centuries BC. The methodology combines RTK-corrected LiDAR (150 pts/m², ±5 cm accuracy) with 20.4 MP RGB imaging, overcoming vegetation cover while capturing surface details. The results demonstrate the superior performance of the proposed methodology compared to public LiDAR (1 m resolution), offering more detailed and precise microtopographic data of the circular structure. The approach successfully addresses three key challenges: (1) dense vegetation penetration, (2) multi-phase stratigraphic documentation, and (3) non-invasive monitoring of sensitive sites. The centimetre-accurate 3D models (publicly available via Sketchfab) provide both research-grade data for analysing construction phases and contextual relationships with nearby rock art/megaliths, and engaging visualisations for heritage interpretation. This work establishes a replicable technical framework optimised for high-resolution archaeological documentation, with direct applicability to similar ritual landscapes (hillforts, burial mounds) across the region. Full article

Dendrochronological analysis was carried out at the archaeological settlement of Gran Carro, located in Lake Bolsena (Italy). According to the most recent archaeological evidence, the site dates back to the period spanning from the Middle Bronze Age (15th century BC) to the Early Iron Age (8th century BC). In the excavation of the archaeological area, wooden piles from deciduous oak species (Quercus section robur and Quercus section cerris) were found, species still common in the area. The analysed trees, aged 15–50 years, likely came from managed forests, though agamic regeneration is possible. Relative felling dates provide initial insights into the duration of the settlement phases, revealing modifications to the original structure over an interval year ranging from 9 to 23 years. Absolute dating using wiggle matching indicates that most of the analysed piles date between 934 and 810 BC, though calibration curve slope limits precision. Nonetheless, dendrochronological analysis suggests that the settlement associated with an individual dendrogroup can likely be placed more precisely within this time range from 907 to 885 BC. From a broader perspective, the excavated area so far indicates that the settlement can be dated with 95% probability to the period 1054–810 BC and with 68% probability to the period 1017–817 BC. The results represent a significant milestone and may offer valuable insights for future investigations and developments. Full article

Miracle tales are almost the sole source for the investigation of the emergence and spread of the relic cult in the early phase of Chinese Buddhism. The earliest excavated relic casket dates back to 453 CE, over four centuries after Buddhism was introduced to China. Through a critical textual analysis of Ji Shenzhou Sanbao Gantonglu, it is evident that the initial form of relic veneration was based on miraculous responses. Legends about imperial relic worship before the 3rd century are all later fabrications. Two archeological finds—the alleged relic murals in a Han tomb at Horinger, Inner Mongolia, and the stūpa-shaped bronze vessel in Gongyi, Henan—are not directly related to relic veneration. Based on the available evidence, it is tentatively concluded that relic worship first emerged around the 3rd century in the vicinity of Luoyang, the capital of the Western Jin, and later spread to the south of the Yangtze River after the Yongjia chaos. The early worshippers included both monks and lay Buddhists, such as merchants and lower-ranking officials. Royal interest in relics did not arise until the 5th century. The rise of relic veneration in China occured two or three centuries later than that in Gandhāra, from which Chinese Buddhism was significantly influenced. Compared to the cult of images or scriptures, relic veneration also emerged relatively late in China. The reluctance to adopt relics as worship objects can be partly explained by (the mahāyāna) Buddhist doctrines and the Chinese cultural mentality. Full article

The influence of heat input (HI) on the microstructure, microhardness, electrochemical corrosion performance of cold metal transfer additively manufactured (CMTAM) nickel–aluminum bronze alloys was investigated. The nickel–aluminum bronze exhibited an α-Cu austenite matrix with minor γ₂-Cu₉Al₄ and κ phases. As HI increased, the microstructure coarsened progressively. Electron backscatter diffraction (EBSD) analysis revealed that with increasing HI, the grain size gradually increased and the Schmid factor increased. Consequently, the microhardness declined from 198.3 HV to 171.7 HV. The decrease in microhardness with increasing heat input is primarily attributed to the grain coarsening and the coarsening and uneven distribution of the κ phase. As the heat input (HI) increased from 243.8 J/mm to 644.7 J/mm, the corrosion current density rose significantly from 2.56 ± 0.04 μA/cm² to 7.52 ± 0.07 μA/cm². This result indicates a marked deterioration in the material’s corrosion resistance. This phenomenon can be attributed to the grain coarsening and the distribution of Al solute within the microstructure. The CMTAM nickel–aluminum bronze alloys hold significant potential for enhancing the reliability and long-term protection of marine engineering equipment. Full article

This study presents a probabilistic analysis of how thermal conductivity and hardness affect surface integrity in CNC turning, focusing on five engineering materials: Aluminum Alloy 6061, Brass C26000, Bronze C51000, Carbon Steel 1020 Annealed, and Stainless Steel 304 Annealed. Surface roughness and waviness parameters were measured across five zones per material under controlled conditions. Results revealed a strong inverse correlation between thermal conductivity and surface irregularities. Aluminum Alloy 6061 (167 W/m·K, 95 HBW) exhibited the best surface finish (R_a_avg ≈ 1.7664 µm; W_a_avg ≈ 0.8242 µm), while Carbon Steel 1020 Annealed (51 W/m·K, 170 HBW) demonstrated the poorest finish (R_a_avg ≈ 4.0780 µm; W_a_avg ≈ 3.8384 µm). Intermediate materials followed consistent trends: Brass C26000 (R_a_avg ≈ 2.5398 µm; W_a_avg ≈ 1.5364 µm), Bronze C51000 (R_a_avg ≈ 1.8862 µm; W_a_avg ≈ 0.9299 µm), and Stainless Steel 304 Annealed (R_a_avg ≈ 0.9031 µm; W_a_avg ≈ 0.5914 µm). High thermal conductivity materials exhibited narrower parameter distributions (σ_R_a ≤ 0.40 µm), while harder materials showed increased variability (σ_R_a ≥ 0.60 µm). Probabilistic models, validated with high confidence (R² > 0.95), offer predictive insights for optimizing machining strategies. These findings support material-specific process adjustments to enhance surface quality, tool life, and functional reliability in aerospace, automotive, and biomedical applications. Full article

Hybrid composite materials reinforced with both fibers and particulate fillers are increasingly used in engineering due to their favorable balance of mechanical strength, reduced weight, and enhanced tribological performance. This study investigated the effect of CuSn10 bronze powder additions (5%, 10%, and 15% by weight) on the mechanical and tribological properties of novel basalt fiber-reinforced polymer (BFRP) composites. The composites were fabricated via vacuum-assisted processing and tested under dry sliding conditions with varying loads (10, 20, and 30 N) and sliding speeds (0.1, 0.25, and 0.36 m/s). The results show that the optimal tensile strength (440.6 MPa) was achieved at 10 wt% CuSn10, while the best tribological performance was observed at 15 wt% CuSn10, under a 10 N load and 0.25 m/s sliding speed, where the coefficient of friction decreased by up to 38% and the specific wear rate was reduced by more than 50% compared to the unreinforced BFRP composite. These enhancements are attributed to the formation of a stable oxide-based tribolayer (CuO, SnO₂) and improved load transfer at the fiber–matrix interface. Statistical analysis (GLM) confirmed that CuSn10 content had the most significant influence on tribological parameters. The findings provide valuable insight into the design of high-performance hybrid composites for structural and tribological applications. Full article

The color of the walnut seed coat is a critical determinant of its market value; however, research into the mechanisms responsible for seed coat color formation is yet to be determined. Using two walnut clones with contrasting pale-yellow and light purple seed coats, we characterized pigmentation, particularly anthocyanin content, using spectrophotometry. We then conducted integrated transcriptomic and metabolomic analyses to identify the molecular mechanisms and pathways underlying their formation. The anthocyanin content in the light purple seed coat clone was significantly greater than that in the clone with a white seed coat. The results of comparative metabolomics indicated that four anthocyanins (delphinidin, cyanidin-3-(caffeoylglucoside), pelargonidin-3-(6″-caffeoylglucoside), and delphinidin-3-O-sophoroside) were significantly more abundant in the light purple seed coat clone. These anthocyanins were the key pigments responsible for the light purple coloration of the walnut seed coat. Furthermore, comparative transcriptomics revealed that structural genes in the anthocyanin biosynthesis pathway (e.g., phenylalanine ammonia-lyase, 4-coumarate-CoA ligase, chalcone isomerase, and bronze-1) were significantly upregulated in the purple seed coat clone. Coexpression network analysis revealed that several transcription factors (e.g., ARF, bHLH, and MYB-related) were significantly correlated with the upregulation of these structural genes and the accumulation of four key anthocyanins. These transcription factors may serve as critical regulators influencing seed coat color formation. In conclusion, these findings establish a strong theoretical foundation for walnut breeding aimed at developing diverse seed coat colors. Full article