Search Results (1,188)

The presented research aims to find a data-driven formula for the compressive stress–strain behaviour of closed-cell aluminium foams with respect to the apparent density of the material. This is a continuation and new development of an earlier study by the authors. In the previous step, 500 artificial neural network models were built and trained on experimental results from compression tests and then evaluated based on, among other factors, mean absolute relative errors for training and verification stages. In this step, the evaluation of networks is amended, and criteria are introduced that are connected with the mechanical characteristics of the material, i.e., the plateau stress and quasi-elastic gradient. A weighted condition of all measures is proposed. Based on the amended conditions, a neural network model with a weighted mean absolute relative error of $\cong 5\%$ is chosen and presented, together with the mathematical equation for its stress–strain–density relationship $\sigma =f\left(\epsilon ,\rho \right)$ over a range of material apparent densities $\rho \in ⟨0.2;0.3⟩ \mathrm{g}/{\mathrm{c}\mathrm{m}}^3$. Experimental relationships for compressive strength and plateau stress are also presented. Full article

Polyurethane foams containing heterocyclic rings are characterized by high thermal resistance, but unfortunately, they are flammable. This work examined the effect of halogen-free flame retardants such as melamine and expanded graphite: EG 096 and EG 290 on the properties of foams with a 1,3-pyrimidine ring. Oligoetherol obtained from 6-aminouracil, ethylene carbonate, and propylene oxide was foamed with polymeric diphenylmethane 4,4′-diisocyanate with the addition of flame retardants. The oxygen index was determined, and flammability tests were conducted on the resulting foams. Their apparent density, water absorption, thermal resistance, thermal conductivity coefficient, and compressive strength were also examined. Both melamine and expanded graphite significantly reduce the flammability of foams. The resulting foams are classified as V-0 flammability class, and their oxygen index is in the range of 24.9–29.5 vol.%. Expanded graphite is a better flame retardant and does not cause deterioration of other foam properties. Full article

The transport of chloride ions in concrete is often affected by electric fields, and its concentration distribution is generally evaluated using the Nernst–Planck equation. The Nernst–Planck theory can only effectively predict the mass electromigration in ideal porous media. However, under an electric field, cementitious materials still have a certain binding ability to chloride ions. This causes the transport model to have significant prediction errors, and the specific value of the electromigration coefficient cannot be accurately measured. This article systematically investigated the transfer rate of chloride ions in cementitious material under different current densities. An analytical solution of the Nernst–Planck equation containing an independent electromigration coefficient was presented, and its value was quantitatively measured and discussed. The results indicated that the relationship between the electromigration and the apparent diffusion coefficient of chloride ions needs to be fitted in segments corresponding to various electric voltage intensities; but the electromigration coefficient shows a highly linear relationship with the pure effective diffusion coefficient. This work can provide assistance and valuable data support for the evaluation of mass transport in non-ideal porous media, such as cementitious materials, using the Nernst–Planck theory. Full article

Copper is a critical material for energy transition and green technologies, making its sustainable use increasingly important. Its superior thermal and electrical conductivity make it highly well-suited for additive manufacturing (AM). In this study, copper sourced from offshore electrical cables was upcycled to produce high-quality metal powder for AM. The scrap was processed to separate the metal from plastic and rubber, then refined through ultrasonic atomization, achieving a purity of ~99.5% wt.% with minimal impurities. Characterization demonstrated good flowability, apparent and tap densities, and a well-distributed particle size. To assess its performance in AM, the powder was printed using Directed Energy Deposition (DED) with a laser beam, confirming its high printability and compatibility with the base material. Finally, a comparative Life Cycle Assessment (LCA) revealed a significant environmental advantage of the recycling-based process over conventional mining, reducing global warming potential by more than 70%. These findings highlight the importance of feedstock origin in AM sustainability and support the adoption of circular economy strategies to lower the environmental footprint of advanced manufacturing. Full article

Wood density is a key property since it affects almost every other property of wood such as its elasto-mechanical, acoustic, thermal, or electrical properties. Hence, it is essential to determine wood density for the interpretation of any other property test. Density measurements are usually carried out gravimetrically by measuring the wood specimens’ dimensions and taking their weight. In order to be independent of moisture, wood density is measured at an absolute dry state. However, depending on which wood properties shall be measured after the oven-dry density is determined, heating the wood up to 103 °C can be problematic because the volatile components of the wood can evaporate. For this reason, the drying conditions (temperature in °C (60, 80, 103 °C)), duration in h (8, 16, 24, 48 h)) required to achieve an absolute dry state inside wood specimens—being obligatory for the analysis of various physical, mechanical, or even biological properties—were examined for different softwood and hardwood species. Basically, oven-dry measurements (i.e., 48 h at 103 °C) themselves contained a significant error, which was considered to be the result of deviations in the handling of the specimens and the scales used. Using temperatures below 103 °C was critical for the determination of absolute dry mass and dimensions. Wood specimens with a high content of volatile ingredients led to an apparently increased residual MC (e.g., shown for Scots pine heartwood), thus volatile ingredients were considered an additional source of error during oven-dry measurements. Full article

Foamed concrete has been widely applied in construction engineering; however, the performance requirements vary across different structural components. Its production typically involves a substantial consumption of cement, which imposes both environmental and economic burdens. Therefore, this study examined foamed concrete with dry apparent densities of 500–1000 kg/m³, in which cement was partially replaced (0–30%) by recycled powder from construction and demolition waste. Macroscopic performance was evaluated through drying shrinkage, compressive strength, softening coefficient, carbonation coefficient, and thermal conductivity, while microstructural analysis was conducted to clarify the underlying mechanisms. The results indicate that the internal composition of the recycled powder primarily consists of SiO₂, CaCO₃, and C-S-H gel. When recycled powder is used to replace cement, the microstructure of the resulting paste gradually deteriorates compared to that of the control group without recycled powder, and a significant amount of inert SiO₂ is introduced. As the replacement ratio of recycled powder increases, the compressive strength of foamed concrete across various density grades exhibits a gradual decline. Notably, when the replacement ratio reaches 30%, the reduction in mechanical performance becomes more substantial. However, the incorporation of recycled powder can effectively mitigate the drying shrinkage of foamed concrete. Moreover, the incorporation of recycled powder exerts minimal influence on the thermal conductivity and porosity of foamed concrete, demonstrating its favorable compatibility and potential for application in foamed concrete systems. Full article

The influence of both mixing pressure and substrate temperature on the structure and properties of spray polyurethane foams produced with a high content (80%) of tall oil-based polyol was investigated. The use of a renewable feedstock such as tall oil polyol aligns with the principles of sustainable development by reducing the carbon footprint and minimizing the environmental impact of the production process. The research focused on identifying the relationships between process parameters and the resulting materials’ thermal insulation properties, physico-mechanical performance, thermal behavior, cellular structure, and chemical composition. The results demonstrated that increasing the mixing pressure (from 12.5 to 17.5 MPa) and substrate temperature (from 40 to 55 °C) led to a reduction in average pore diameter, an increase in closed-cell content up to 94.5% and improved structural homogeneity. The thermal conductivity coefficient (λ) ranged from 18.55 to 22.30 mW·m⁻¹·K⁻¹ while apparent density varied between 44.0 and 45.5 kg·m⁻³. Higher mixing pressure positively affected compressive strength, whereas elevated substrate temperature reduced this parameter. Brittleness, water uptake, and dimensional stability remained at favorable levels and showed no significant correlation with processing conditions. These findings confirm the high quality of the materials and highlight their potential as sustainable, environmentally friendly insulation foams. Full article

This study investigated a compound low-protein diet (CLPD) strategy to reduce soybean meal (SBM) dependency in meat geese. Diets were formulated with crude protein (CP) levels decreasing from 16.5% (corn-soybean meal diet, CSD) to 9.8%, incorporating alternative ingredients such as rapeseed meal, corn distillers dried grains with solubles (DDGS), broken rice, and rice bran. All diets were balanced for limiting amino acids (lysine, methionine, threonine, and valine) through supplemental synthetic amino acids. A total of 192 four-week-old Sanhua geese were randomly assigned according to a single-factor completely randomized design to four dietary treatment groups: the 16.5% (CSD) group and three CLPD treatment groups (14.0% CP, 11.5% CP, and 9.8% CP). Each treatment consisted of six replicate pens with eight geese per pen. During the six-week trial, evaluations included growth performance, organ weights, nutrient digestibility, serum biochemistry, amino acid profiles, intestinal morphology, and cecal microbiota composition. Results demonstrated that compared to the 16.5% (CSD) group, the 11.5% CP (CLPD) group significantly improved final body weight (p < 0.05), average daily gain (P_Linear < 0.01, p < 0.05), and feed conversion efficiency (P_Linear < 0.01, p < 0.05), alongside enhanced apparent digestibility of crude protein and amino acids (P_Linear < 0.01, p < 0.05). Organ weights were generally stable, though the 9.8% CP (CLPD) group showed reduced liver weight (p < 0.05) and increased abdominal fat (P_Linear < 0.01, p < 0.05). Serum levels of low-density lipoprotein cholesterol increased (P_Linear < 0.05, p < 0.05). Intestinal morphology improved in the duodenum and jejunum: in the duodenum, villus height and villus-to-crypt ratio were significantly increased, and crypt depth was significantly decreased (P_Linear < 0.01, p < 0.05); in the jejunum, villus height was significantly increased (p < 0.05) and crypt depth was significantly decreased (p < 0.05). Cecal microbiota alpha diversity remained consistent. The dominant genera in the 9.8% CP (CLPD) group were unclassified_Oscillospiraceae and unclassified_Ruminococcaceae (p < 0.05), among which, Megamonas, Prevotellaceae_Ga6A1_group, and Rikenellaceae_RC9_gut_group dominated in the 16.5% (CSD) group (p < 0.05). These findings indicate that a compound low-protein diet (CLPD) with 11.5% CP, precisely balanced for limiting amino acids, supports optimal growth performance, improves nutrient utilization, and maintains intestinal health in meat geese. Overall, this offers a viable approach to easing SBM reliance in poultry nutrition while enhancing resource efficiency. Full article

The spray drying of hard metal (WC-Co) powders is a critical step in the production of high-performance cutting and wear-resistant tools. Traditionally, organic solvents such as ethanol or acetone are employed in this process, despite posing substantial health, safety, and environmental risks. This study investigates a sustainable alternative by replacing organic solvents with water in the spray-drying process. We present a comparative analysis of granule morphology, flowability, and final mechanical properties between solvent-based and water-based routes. The water-based approach achieved a d₅₀ of 99 µm, flow time of 27.8 s, and apparent density of 3.18 g/cm³, closely matching the solvent-based values (d₅₀ = 93 µm, flow = 28.4 s, and ρ = 3.14 g/cm³). Hardness (HV30 ≈ 1650) and microstructure were equivalent across both routes, confirming that the substitution does not compromise performance. The water-based process also offers an estimated reduction of over 50% in CO₂ emissions compared to traditional methods. These findings support the feasibility of water-based granulation as a viable, scalable, and safer route for WC-Co powder production, in alignment with dematerialization, circular material use, and the broader goals of sustainable development. Full article

Paratuberculosis or Johne’s disease is caused by Mycobacterium avium subsp. paratuberculosis (MAP). The disease is characterized by a chronic and incurable enteritis in ruminants and it is responsible for significant economic losses, also raising concerns about food safety and animal welfare. Effective control is hindered by diagnostic limitations, long incubation periods, and the environmental resistance of the pathogen. This study aimed to reduce the apparent prevalence of paratuberculosis in a single intensive dairy herd through an integrated approach that combines diagnostics and management strategies. All cows over 24 months of age were tested using both fecal PCR and ELISA serology. Digital PCR (dPCR) was used to quantify MAP shedding in fecal-positive animals, enabling prioritization for removal based on environmental contamination risk. Integrating diagnostic tools allowed the precise identification and quantification of high-risk animals. Meanwhile, structural improvements and biosecurity measures were implemented on the farm. Preliminary outcomes suggest a marked reduction in herd-level MAP prevalence, lowering the seroprevalence from 7.6% to 4.5% and the fecal PCR prevalence from 6.5% to 2.8%. This case highlights the effectiveness of combining laboratory testing (serology and molecular diagnostics) and targeted changes in farm management to control paratuberculosis in high-density dairy systems. Full article

Producing second-generation (2G) bioethylene through the dehydration of 2G bioethanol is a challenge, requiring the effective use of catalysts as an alternative to fossil-based ethylene production. This work evaluates the production of bioethylene from the catalytic dehydration of 2G bioethanol [from pine sawdust produced via a simultaneous saccharification and fermentation SSF process (53%)] using γ-Al2O3; ZSM-5, NH₄⁺Y, H-ZSM-5, and H-Y zeolite as catalysts. Yields of 94.6% (at 372 °C) and 85.5% (at 473 °C) of 2G bioethylene were obtained when using H-ZSM-5 and H-Y zeolite, respectively. These results demonstrate that the H-ZSM-5 zeolite showed the best performance for 2G bioethanol dehydration, producing high 2G bioethanol conversion and 2G bioethylene selectivity at a lower reaction temperature. Ethylene production from the catalytic dehydration of commercial (96%) and diluted (53%) ethanol was evaluated as a reference, along with the effects of the weight hourly space velocity (WHSV) and ethanol concentration. Varying the WHSV from 2.37 to 4.73 h⁻¹ at 312 °C and using commercial ethanol at 96%, produced similar ethanol conversion of 100% and ethylene yield of 100%. At 290 °C, with a WHSV of 2.37 h⁻¹ and 53% diluted commercial ethanol, H-ZSM-5 converted 76.83% of the ethanol and produced a 75.8% ethylene yield. A study based on density functional theory (DFT) has shown that diethyl ether is a key intermediate in the conversion mechanism on H-ZSM-5, proceeding through an ethoxide intermediate in the rate-determining step, with an apparent activation energy of 25.4 kcal mol⁻¹. Full article

Background: Chronic Recurrent Multifocal Osteomyelitis (CRMO) is a rare auto-inflammatory condition affecting the growing skeleton. The standard first-line treatment of high-dose NSAIDs (non-steroidal anti-inflammatory drugs) is adequate only in a subset of patients. The American College of Rheumatology Consensus Guidelines suggest considering bisphosphonates in a certain category of patients based on evidence from a handful of case series reporting the outcome of pamidronate use. Aims: The aim of this study was to report the efficacy and safety of bisphosphonate, predominantly zoledronate, use in CRMO. Methods: A retrospective cohort study of children with CRMO receiving bisphosphonates was conducted between January 2008 and September 2023 at a single tertiary referral centre. We described the baseline characteristics; clinical indication, regimen and response to bisphosphonate treatment; changes in bone mineral density (BMD) and spine remodelling on dual-energy X-ray absorptiometry (DXA) scans; and safety data. Results: During the study period, 64 (72%, n = 46 females) patients with CRMO with a median age at diagnosis of 10 years (range: 3 to 16 years) were identified. Approximately 31% (n = 20) received either pamidronate (n = 2) or zoledronate (n = 14) or both (n = 4) due to changes in local protocols. The most frequent indications for bisphosphonate use were refractory pain [55%, n = 11/20], pain + spine involvement [35% (n = 7/20)] and spine involvement only [10% (n = 2)]. Prior to bisphosphonate therapy, 100% took regular NSAIDs (n = 19/19), 21% (n = 4/19) used opioids, 47% (n = 9/19) received oral steroid courses, and 10% (n = 2/19) received methotrexate. The median age at bisphosphonate treatment initiation was 12 years (range 6–18 years), and the duration of treatment was 2 years (range: 6 months to 5 years). Improvement in pain was reported by 88% of patients (n= 15/17, 1 was excluded as they had not started treatment yet). All non-responders (n = 2/17;) to bisphosphonate therapy were later recognised clinically to have pain amplification syndrome and were referred to the chronic pain multi-disciplinary team. This correlated to the complete treatment de-escalation of opioids (n = 3/3; 1 was excluded as they had not yet started treatment), steroids (n = 8/8) and methotrexate (n = 2/2). NSAIDs were discontinued in 44% of patients (n = 7 of 16; 1 was excluded due to missing data, and 3 were excluded due to NSAID intolerance). The median first-year increase in the LS BMAD (lumbar spine bone mineral apparent density) Z-score was +1.35, and that in the TBLH BMD (total body less head bone mineral density) Z-score was +0.7 (n = 11). Subsequently, median average annual increases in the LS BMAD Z-score of +0.65 and in the TBLH BMD Z-score of +0.45 (n = 5) were recorded. Around 30% of patients (n = 6) required treatment modification (dose reduction, frequency reduction or cessation) due to a rapid escalation in BMD. There were no fractures documented due to raised BMD. Evidence of spine remodelling on DXA vertebral fracture assessment was seen in 38% of patients with spinal lesions (n = 3 of 8). There was no radiological evidence of improvement in any vertebra plana lesion. First-phase reactions (pyrexia) were reported universally in patients who received bisphosphonates, but none were significant requiring hospitalisation. Conclusions: Similar to pamidronate, zoledronate with an advantageous dosing regimen is well tolerated and effective in improving pain and enabling the de-escalation of adjunctive therapy in CRMO. This is the first report tracking changes in BMD and spinal remodelling in response to zoledronate in CRMO patients. Spinal remodelling is minimal in vertebra plana lesions. Bone density monitoring and personalisation of the bisphosphonate dose and regimen are strongly recommended to avoid overtreatment. Full article

With the advancement of scientific research, understanding the physical parameters governing acoustic wave propagation in sea ice has become increasingly important. Among these parameters, shear wave velocity plays a crucial role. However, as measurements progressed, it became apparent that there was a large discrepancy between measured values of shear waves and predictions based on empirical formulas or existing models. These inconsistencies stem primarily from the complex internal structure of natural sea ice, which significantly influences its physical behavior. Research reveals that shear wave velocity is not only influenced by bulk properties such as density, temperature, and stress state but is also sensitive to microstructural features, including air bubbles, inclusions, and ice crystal orientation. Compared to longitudinal wave velocity, the characterization of shear wave velocity is far more challenging due to these inherent complexities, underscoring the need for more precise measurement and modeling techniques. To address the challenges posed by the complex internal structure of natural sea ice and improve prediction accuracy, this study introduces a novel, integrated approach combining simulation, measurement, and inversion intelligent learning model. First, a laboratory-based method for generating sea ice layers under controlled formation conditions is developed. The produced sea ice layers align closely with measured values for Poisson’s ratio, multi-year sea ice density, and uniaxial compression modulus, particularly in the high-temperature range. Second, enhancements to shear wave velocity measurement equipment have been implemented. The improved device achieves measurement accuracy exceeding 1%, offers portability, and meets the demands of high-precision experiments conducted in harsh polar environments. Finally, according to the characteristics of small sample data. The ANN neural network was improved to a deep residual neural network with the addition of Squeeze-and-Excitation Attention (SE-ResNet) to predict longitudinal and transverse wave velocities. This prediction method improves the accuracy of shear and longitudinal wave velocity prediction by 24.87% and 39.59%, respectively, compared to the ANN neural network. Full article

This study investigates the feasibility of incorporating chemically recycled polyol (glycolysate), derived from semi-rigid polyurethane waste from the building industry, into rigid PUF formulations intended for thermal insulation applications. Glycolysis was performed using a diethylene glycol–glycerol mixture (4:1) at 185 °C in the presence of a dibutyltin dilaurate (DBTDL) catalyst. The resulting glycolysate was characterized by a hydroxyl number of 590 mg KOH/g. Foams containing 5–50% recycled polyol were prepared and described in terms of foaming kinetics, cellular structure, thermal conductivity, apparent density, mechanical performance, dimensional stability, flammability, and volatile organic compound (VOC) emissions. The incorporation of glycolysate accelerated the foaming process, with the gel time reduced from 44 s to 16 s in the sample containing 40% recycled polyol, enabling a reduction in catalyst content. The substitution of up to 40% virgin polyol with recycled polyol maintained a high closed-cell content (up to 87.7%), low thermal conductivity (λ₁₀ = 26.3 mW/(m·K)), and dimensional stability below 1%. Additionally, compressive strength improvements of up to 30% were observed compared to the reference foam (294 kPa versus 208 kPa for the reference sample). Flammability testing confirmed compliance with the B2 classification (DIN 4102), while preliminary qualitative VOC screening indicated no formation of additional harmful volatile compounds in glycolysate-containing samples compared to the reference. The results demonstrate that glycolysate can be effectively utilized in high-performance insulation materials, contributing to improved resource efficiency and a reduced carbon footprint. Full article

Lump charcoal is used in various applications, with combustion performance reliant on physical properties including apparent density. Currently, apparent density is measured by liquid displacement using Archimedes’ principle, which can yield inconsistent results for porous, irregular materials. This study investigates structure-from-motion (SfM) photogrammetry as a non-destructive alternative for estimating the apparent density of lump charcoal. Ninety fragments from 15 commercial samples were analyzed. Mass was measured using an analytical balance, and volume was estimated independently via Archimedes’ method and photogrammetry. Apparent density was calculated as the ratio of mass to volume. Results showed strong agreement between the two methods. Mean density values ranged from 284.2 to 751.6 kg/m³ for photogrammetry and from 267.2 to 765.7 kg/m³ for Archimedes. No significant differences were found (Wilcoxon test, p > 0.05), and a strong correlation was observed (Spearman’s ρ = 0.94, p < 0.001). Photogrammetry also demonstrated low estimation errors, with a mean absolute error of 38.8 kg/m³, a percentage error of 9.9%, and a root mean squared error of 50.2 kg/m³. Beyond methodological innovation, this approach strengthens sustainability by supporting accurate fuel properties control, allowing better use of the resource and maximizes combustion efficiency. In this way, it contributes to United Nations Sustainable Development Goal 7 (SDG7) on affordable, reliable, and sustainable energy. Full article