Search Results (759)

While acetic acid has proven effective as a mild acidic treatment for removing adhered mortar from recycled concrete aggregate (RCA) surfaces, its potential for dissolving damage to the surface of the original natural coarse aggregate (NCA) within the RCA and its impact on the resultant concrete properties require careful consideration. This investigation systematically evaluates the effects of varying concentrations of dilute acetic acid solutions, commonly used in RCA treatment protocols, through a multi-methodological approach that includes comprehensive physical characterization, stylus and 3D optical profilometry, scanning electron microscopy (SEM), and nanoindentation analysis. The results show that even dilute acid solutions have an upper concentration limit, as excessive acid concentration, specifically 0.4 M, induces significant textural dislocations on NCA surfaces, creating millimeter-scale erosion pits that increase aggregate water absorption by 18.5%. These morphological changes significantly impair concrete workability and reduce compressive strength performance. Furthermore, microstructural analysis reveals a 45.24% expansion in interfacial transition zone (ITZ) thickness, accompanied by notable reductions in elastic modulus and microhardness characteristics. In practical RCA treatment applications, for RCA containing limestone-based NCA, it is recommended to use acetic acid concentrations between 0.1 and 0.3 M to avoid substantial physical and microstructural degradation of aggregates and concrete. Full article

An analysis of the existing methods of sintering diamond-containing composites is presented. On the basis of mathematical modeling and experimental studies, the conditions of the laser liquid-phase sintering of diamond-containing composites under which they retain their strength are determined. The energy and technological parameters of the laser irradiation process are characterized, which determine the range of laser processing modes within which no oxidation and crack formation occur, and a high-quality composite with specified geometrical parameters is formed. It has been proven that composites consisting of synthetic diamond grains and a metal bond do not lose strength under the condition that the temperature during laser heating does not exceed 1600 °C and the exposure time is 0.3 s. Electron microscopy and X-ray diffractometry were used for experimental studies of the microstructure and phase composition of the sintered layers. A new design and manufacturing method for a drum-type abrasive tool with replaceable diamond inserts for grinding large-sized aircraft and shipbuilding products are proposed. Components of a laser technological complex for the implementation of the process of sintering the diamond-containing layer of the abrasive inserts of the drum have been developed. Full article

The use of short cylinders of recycled aggregate concrete (RAC) reinforced with basalt fiber-reinforced polymer (BFRP) circumferential strips and polyvinyl chloride (PVC) tubes has been proven effective in previous studies. However, BFRP circumferential strips are cumbersome to install and do not ensure the integrity of the BFRP strips. Therefore, this study investigates axial compression experiments on RAC short cylinders reinforced with BFRP spiral strips and PVC tubes. A combination of experimental studies, finite element simulations, and theoretical analyses revealed that the winding angle and spacing of BFRP strips significantly affect the load-bearing capacity and ductility of the restrained specimens. Additionally, an improved strength model was developed based on an existing model. When evaluated using both computational and experimental results, the equations generated in this study showed an average error of less than 10%. The findings indicate that the composite structure provides effective reinforcement and offers valuable reference information for practical applications. Full article

This research presents a novel method for detecting building roof types using deep learning models based on height profiles from high-resolution digital surface models. While deep learning has proven effective in digit, handwritten, and time series classification, this study focuses on the emerging and crucial area of height profile detection for building roof type classification. We propose an innovative approach to automatically generate, classify, and detect building roof types using height profiles derived from normalized digital surface models. We present three distinct methods to detect seven roof types from two height profiles of the building cross-section. The first two methods detect the building roof type from two-dimensional (2D) height profiles: two binary images and a two-band spectral image. The third method, vector-based, detects the building roof type from two one-dimensional (1D) height profiles represented as two 1D vectors. We trained various one- and two-dimensional convolutional neural networks on these 1D and 2D height profiles. The DenseNet201 network could directly detect the roof type of a building from two height profiles stored as a two-band spectral image with an average accuracy of 97%, even in the presence of consecutive chimneys, dormers, and noise. The strengths of this approach include the generation of a large, detailed, and storage-efficient labeled height profile dataset, the development of a robust classification method using both 1D and 2D height profiles, and an automated workflow that enhances building roof type detection. Full article

Meteorological observations are essential for climate modelling, prediction, early warning systems, decision-making processes, and disaster management. These observations are critical to societal development and the safeguarding of human activities and livelihoods. Spatial interpolation techniques play a pivotal role in addressing gaps between observation sites, enabling the generation of continuous meteorological datasets. However, due to the inherent complexity of atmosphere–surface interactions, no single interpolation technique has proven universally effective in achieving consistently accurate results for meteorological variables. This study proposes a novel interpolation model based on Fuzzy Adaptive Optimal Fusion (FAOF). The FAOF model integrates fuzzy theory by constructing station-specific fuzzy sets and sub-method element pools, employing a nonlinear membership function with error as the independent variable. An iterative accuracy index is used to identify the optimal parameter combination, facilitating adaptive data fusion and interpolation optimisation. The model’s performance is evaluated against 10 individual methods from the method pool. Experimental results demonstrate that FAOF effectively combines the strengths of multiple methods, achieving significantly enhanced interpolation accuracy. Additionally, the model consistently performs well across diverse regions and meteorological variables, underscoring its robustness and strong generalisation capability. Full article

In this study, free compression tests were conducted to examine the changes in the strength of soil after adding 24 mm long basalt fiber (1%), lime (3%, 6%, 9% by dry weight), and tuff (10%, 20%, 30% by dry weight) before curing and after 28, 42, and 56 days of curing. Instead of the K + BF 1% + SL 9% mixture, where the SL ratio is high, it has been revealed that T, which has a lower SL content and is environmentally friendly (as in the K + BF 1% + SL 6% + T 10% mixture), can be used considering environmental factors and costs. However, due to the length and cost of experimental studies, the use of artificial intelligence to reduce the need for physical tests/experiments and to accelerate processes will provide savings in terms of labor, time, and cost. Unconfined compressive strength (q_u) prediction was performed using the artificial neural network (ANN) technique. The accuracy of the ANN model was proven using the R and MSE metrics. In addition, a q_u prediction of the mixture with 30% water content was performed according to the curing times. The experimental and predicted q_u values for the curing times were compared and presented. Full article

Due to their biocompatibility, biodegradability, injectability, and self-setting properties, calcium–magnesium phosphate cements (MCPCs) have proven to be effective biomaterials for bone defect filling. Two types of MCPC powders based on the magnesium whitlockite or stanfieldite phases with MgO with different magnesium contents (20 and 60%) were synthesised. The effects of magnesium ions (Mg²⁺) on functional properties such as setting time, temperature, mechanical strength, injectability, cohesion, and in vitro degradation kinetics, as well as cytocompatibility in the MG-63 cell line and the osteogenic differentiation of BM hMSCs in vitro, were analysed. The introduction of NaHA into the cement liquid results in an increase in injectability of up to 83%, provides a compressive strength of up to 22 MPa, and shows a reasonable setting time of about 20 min without an exothermic reaction. These cements had the ability to support MG-63 cell adhesion, proliferation, and spread and the osteogenic differentiation of BM hMSCs in vitro, stimulating ALPL, SP7, and RUNX2 gene expression and ALPL production. The combination of the studied physicochemical and biological properties of the developed cement compositions characterises them as bioactive, cytocompatible, and promising biomaterials for bone defect reconstruction. Full article

Osteoporosis is a prevalent disease among the elderly, with fractures being one of the most serious consequences. Early diagnosis and accurate assessment of fracture risk could help prevent fractures. Radiomics employs advanced image analysis techniques for the development of diagnostic tools, thereby improving the accuracy of disease diagnosis and treatment strategies. Specifically, in the application of bone diseases, radiomics has proven effective in the diagnosis and prognostic evaluation of osteoporosis, osteoarthritis, and bone tumors. Radiomics allowed for quantitative characterization of bone geometry, material distribution, and microstructure, making it applicable to osteoporosis as well. In this review, an overview was provided regarding the current progress of radiomics based on clinical bone imaging in osteoporosis, including bone strength assessment, osteoporosis diagnosis, and fracture risk prediction. Additionally, the potential and challenges for their clinical application were summarized. Full article

The COVID-19 pandemic has presented significant challenges to global healthcare, bringing out the urgent need for reliable diagnostic tools. Computed Tomography (CT) scans have proven instrumental in detecting COVID-19-induced lung abnormalities. This study introduces Convolutional Neural Network, Graph Neural Network, and Vision Transformer (ViTGNN), an advanced hybrid model designed to enhance SARS-CoV-2 detection by combining Graph Neural Networks (GNNs) for feature extraction with Vision Transformers (ViTs) for classification. Using the strength of CNN and GNN to capture complex relational structures and the ViT capacity to classify global contexts, ViTGNN achieves a comprehensive representation of CT scan data. The model was evaluated on a SARS-CoV-2 CT scan dataset, demonstrating superior performance across all metrics compared to baseline models. The model achieved an accuracy of 95.98%, precision of 96.07%, recall of 96.01%, F1-score of 95.98%, and AUC of 98.69%, outperforming existing approaches. These results indicate that ViTGNN is an effective diagnostic tool that can be applied beyond COVID-19 detection to other medical imaging tasks. Full article

Microwave curing has proven to be a highly effective method for enhancing the structural integrity, compressive strength, and heavy metal immobilization performance of geopolymer (GP) gels. For fly ash-based GP gels, optimal compressive strength (126.84 MPa) and minimal heavy metal ion leaching (0.01 mg/L) were achieved under microwave irradiation at 100 W for 75 s. Similarly, metakaolin-based GP gels reached peak compressive strength (76.84 MPa) and reduced heavy metal leaching (0.44 mg/L) under 440 W irradiation for 60 s. Microwave energy significantly accelerates geopolymerization by promoting the aggregation of dispersed particles, rapidly forming a dense, block-like matrix. This accelerated densification enhances the mechanical properties of GP gels within minutes. Moreover, the dense matrix structure effectively encapsulates heavy metal ions, minimizing their leaching through a combination of physical encapsulation and chemical bonding. In summary, microwave treatment significantly enhances both mechanical performance and heavy metal immobilization, offering a practical pathway for sustainable applications. Full article

Background: High-intensity intermittent training (HIIT) has been proven to improve cardio-metabolic and respiratory health outcomes. In addition, 20-hydroxyecdysone from plant extracts has been studied for its anabolic effects. However, studies examining these two interventions in individuals who are obese or overweight are limited. This study, thus, examined the effects of HIIT combined with Asparagus officinalis (A. officinalis) extract supplementation on cardiovascular and pulmonary function parameters in obese and overweight individuals. Methods: Seventy-two obese and overweight participants were randomized into four groups (n = 18 each): the control (CON) group; HIIT group (HIIT for 3 days/week); AOE (A. officinalis extract) group (supplementation with 20E at 1.71 mg/kg/day); and HIIT + AOE group. Pre- and 12-week post-intervention measures included heart rate (HR), HR variability, endothelial function, blood pressure (BP), BP variability, pulmonary function and volume, respiratory muscle strength, chest expansion, and body composition. Results: The HIIT + AOE group showed better HR variability with higher high-frequency power and a lower low-frequency/high-frequency ratio (both p = 0.038) compared to the CON group. The peak blood flow increased in both the HIIT (p = 0.03) and HIIT + AOE (p = 0.028) groups, but only the HIIT group had a shorter vascular recovery time (p = 0.048). The maximum expiratory pressure was increased in both the HIIT and HIIT + AOE groups compared to the CON group (p = 0.029 and p = 0.041). The ratio of forced expiratory volume in one second to forced vital capacity, the percent-predicted FEV₁/FVC, and chest wall expansion were higher in the HIIT + AOE group than in the CON group (p = 0.047, p = 0.038, and p = 0.001). The waist-to-hip ratio was lower in the HIIT + AOE group than in the CON group (p = 0.043). There were no significant differences in HR, BP, BP variability, or pulmonary volume parameters among groups. Conclusions: The combination of HIIT with A. officinalis extract supplementation markedly improves HR variability. Moreover, it also greatly improves expiratory muscle strength, chest wall expansion, pulmonary function, and body composition parameters in obese and overweight individuals. Full article

Self-compacting concrete (SCC) is an innovative building material that is distinguished by its ability to flow and fill forms without the need for mechanical vibration. The aim of this research was to determine the effect of different types of fibres—steel, glass, and polypropylene—on the properties of both the fresh mix (consistency, density, air content, and viscosity) and the hardened concrete (compressive strength, tensile strength in bending, density, water absorption, and frost resistance). Attention was also paid to CO₂ emissions associated with cement production and the potential of their reduction by using alternative materials. The results of the conducted research demonstrate that, in terms of enhancing the mechanical properties of self-compacting concrete (SCC), the incorporation of glass fibres (GFs) leads to the most significant improvements in compressive and flexural strength—by 1.6% and 29.2%, respectively. Therefore, these fibres can be recommended for use in high-performance structural applications, such as precast elements, load-bearing components, and structures subjected to dynamic loading. Polypropylene fibres (PPFs), owing to their ability to reduce water absorption by 7.3%, may be suitable for elements exposed to high humidity and shrinkage risk, such as tunnels, fire-resistant barriers, or insulating layers. Steel fibres (SFs), in turn, have proven particularly effective in SCC used for industrial flooring and other elements exposed to cyclic dynamic loads. Full article

Nasal drug delivery faces numerous challenges related to the ineffectiveness of most nasal formulations without a mucoadhesive nature, prolonging residence time on the nasal mucosa. Another challenge is the low administrable dosage strength, which can be solved via nano-encapsulation techniques, including the utilization of polymeric micelles. In this study, gellan gum–cellulose derivative complex in situ gelling matrices were formulated to test their effect on the colloidal characteristics of polymeric micelles, their respective rheological behavior, and nasal applicability. It has been proven that these complex matrices can form gels upon contact with nasal fluid without disrupting the micellar structure. Changes in the drug release and permeation profile have been shown in a concentration-dependent manner to hinder the burst-like drug release profile of polymeric micelles. Formulations show concentration- and composition-dependent mucoadhesive features under nasal conditions. Most of the hydrogels possess a soft gel characteristic, making them suitable for nasal administration. In conclusion, this descriptive study provides useful insights for conscious, nasal dosage form design. Full article

The selection of mining cutting tools used on the cutting heads of roadheaders and shearers in hard coal mines is primarily based on the uniaxial compressive strength (UCS) of the rock. However, selecting cutting tools solely on the basis of a single parameter characterizing the rock has proven to be insufficient. Therefore, the aim of the presented study was to develop guidelines for the selection of cutting tools with appropriate protective coatings on the working parts, based not only on the mechanical strength properties of rocks, but also on their abrasivity. For the study, twelve rock samples were collected from five different Polish hard coal mines. For each rock type, the UCS (uniaxial compressive strength), BTS (Brazilian tensile strength), and chemical composition (determined using wavelength-dispersive X-ray fluorescence, WD-XRF) were measured, along with the rock abrasivity index Wz, determined using a proprietary method developed at the AGH University of Krakow. The test results were compared with the calculated specific pick wear, defined as the number of picks consumed (replaced) per 1000 m³ of excavated material. As a result, a classification of rocks based on their UCS and abrasivity was developed, along with recommendations for selecting conical picks with suitable protective coatings on the working parts. Full article

This study tested the effectiveness of a bifunctional polysiloxane (L43) as a means of protecting concrete surfaces from biocorrosion. L43 was designed to contain two types of functional groups in its structure: surface-active hydrophobic chains and hydrophilic groups that allow the coating to permanently bond to the concrete. L43-coated cement samples achieved compressive strengths exceeding 70 MPa, while samples subjected to cyclic freeze–thaw tests achieved compressive strengths exceeding 33 MPa. In addition, compound L43 at a concentration of 5% reduced the photosynthetic activity of microalgae cells on the concrete surface. The maximum value of chlFI decreased by 69.5%, while the average value decreased by 71.4%. Thus, it was proven that compound L43 effectively counteracts biological corrosion without deteriorating the structure of the impregnated substrate. It should be emphasized that the biocidal effect is due to the structure of the siloxane compound and appropriately selected functional groups. There is no need to add harmful biocides, making the solution environmentally friendly. In addition, the coating allows for free air circulation, which is crucial for the protection of building and construction materials. Full article