Search Results (64)

Myocardial infarction (MI) remains one of the most common cardiovascular diseases and a leading cause of morbidity and mortality worldwide. In recent years, natural polymeric patches have attracted increasing attention as a promising therapeutic platform for myocardial tissue repair. This study explored the fabrication and evaluation of screen-printed electrodes (SPEs) on chitosan film as a novel platform for cardiac patch applications. Chitosan is a biodegradable and biocompatible natural polymer that provides an ideal substrate for SPEs, providing mechanical stability and promoting cell adhesion. Silver ink was employed to enhance electrochemical performance, and the electrodes exhibited strong adhesion and structural integrity under wet conditions. Mechanical testing and swelling ratio analysis were conducted to assess the patch’s physical robustness and aqueous stability. Silver ink was employed to enhance electrochemical performance, which was evaluated using cyclic voltammetry. In vitro, electrical stimulation through the chitosan–SPE patch significantly increased the expression of cardiac-specific genes (GATA-4, β-MHC, troponin I) in bone marrow mesenchymal stem cells (BMSCs), indicating early cardiogenic differentiation potential. In vivo, the implantation of the chitosan–SPE patch in a rat MI model demonstrated good tissue integration, preserved myocardial structure, and enhanced ventricular wall thickness, indicating that the patch has the potential to serve as a functional cardiac scaffold. These findings support the feasibility of screen-printed electrodes fabricated on chitosan film substrates as a cost-effective and scalable platform for cardiac repair, offering a foundation for future applications in cardiac tissue engineering. Full article

Carbon nanotubes (CNTs) exhibit high strength and high modulus, excellent electrical and thermal conductivity, good chemical stability, and unique electronic and optical properties. These characteristics make them a one-dimensional nanomaterial with extensive potential applications in fields such as composite materials, electronic devices, energy, aerospace, and medical technology. Cement-based materials are the most widely used and extensively applied construction materials. However, these materials have disadvantages such as low tensile strength, brittleness, porosity, shrinkage, and cracking. In order to compensate for these shortcomings, in recent years, relevant scholars have proposed to integrate CNTs into cement-based materials. Incorporating CNTs into cement-based materials not only enhances the microstructure of these materials but also improves their mechanical, electrical, and durability properties. The characteristics and fabrication process of CNTs are reviewed in this paper. The different effects of CNTs on the physical properties and hydration properties of cement-based materials due to the design parameters, dispersion methods, and temperature were analyzed. The results show that the compressive and flexural strength of CNT cement-based materials with 0.02% content increased by 9.33% and 10.18% from 3 d to 28 d. In terms of reducing the shrinkage and carbonization resistance of the cement base, there is an optimal amount of carbon nanotubes. The addition of dispersed carbon nanotubes reduces the resistivity, and the nucleation of carbon nanotubes promotes the hydration reaction. In general, under the optimal dosage, carbon nanotubes with uniform dispersion and short length–diameter ratio have a significant effect on the cement-based lifting effect. In the future, CNT cement-based materials will develop high strength, multifunctionality, and low cost, realizing intelligent self-sensing and self-repair and promoting green and low-carbon manufacturing. Breakthroughs in decentralized technology and large-scale applications are key, and they are expected to help sustainable civil engineering with intelligent infrastructure. Full article

The objective of this study was to evaluate the influence of the mean individual volume per tree (MIV) on the productivity of forwarder machines and the production cost in eucalyptus plantations located in southern Bahia, Brazil. MIV positively influenced the productivity and production costs, promoting a more attractive cost in the latter when the individual volume per tree increased. The machine’s productivity for MIV of 0.13 m³ was 42.06 cubic meters per effective working hour (m³Ewh⁻¹), while the productivity for the MIV of 0.58 m³ reached 60.97 m³Ewh⁻¹, corresponding to an increase of 42.59% between the minimum and maximum MIV classes. The extracted cost (m³) decreased by 30.12% from USD 2.49 to 1.74, respectively, when comparing the minimum and maximum MIV classes. The coefficient of determination obtained in the forwarder productivity modeling was significant (R² = 92%), indicating the machine’s productivity can be explained by the mean individual volume per tree. The highest forwarder yields in the highest average volume per tree (MIV) classes provided better energy efficiency indices for the machine; that is to say, when the forwarder became more productive, the ratio between fuel consumption per cubic meter of timber harvested decreased, providing better performance for the respective index. There was a difference in extraction costs of USD 147.83 per hectare between the lowest and highest productivity forests (MIV varying from 0.15 to 0.58). The mechanical availability and mean operational efficiency of all forwarders evaluated were above 80%, which contributed to effective machine productivity performance. Maintenance and repairs represented the largest portion of operational costs (33.59%), followed by labor (22.49%), depreciation (14.33%), and fuel (10.11%). Full article

Straw biochar (BC) and four innovative biochar environmental materials (AFFA/BC) were synthesized via oxygen-limited pyrolysis at different ratios and applied for the remediation of lead (Pb)-contaminated soils. Accelerated aging, which mimics the effects of natural aging on heavy metal fixation properties, was induced through alternating dry and wet conditions. Two models, which are based on conditional probability-induced failures, were developed to characterize the aging process more effectively. The results indicated that the novel biochar material presented elevated Si, Al, and Na contents, increased specific surface area, pore volume, and yield, and the formation of chemical bonds such as T-O-T and T-O (T = Si or Al). Simultaneously, synchronous and asynchronous spectral analysis methods were used to demonstrate that fly ash leads to the formation of new chemical bonds and protects the functional groups of biochar from the destructive effects of high temperatures. Compared with the original biochar, the application of the new biochar material to Pb-contaminated soil increased the soil pH, cation exchange capacity (CEC), and soil organic matter (SOM) content while reducing toxic Pb leaching, resulting in conversion to a more stable residual state. Throughout wet–and–dry cycles, the Pb leaching concentration from the soil gradually increased, with AFFA/BC-2 resulting in a lower aging rate. This study provides a method for preparing low-cost and green soil amendments, which have great potential for repairing HM-contaminated soil and achieving value-added utilization of coal-based solid waste and agricultural waste. Full article

Bioremediation is widely recognized as a promising and efficient approach for the elimination of Cd from contaminated paddy soils. However, the Cd removal efficacy achieved through this method remains unsatisfactory and is accompanied by a marginally higher cost. Cysteine has the potential to improve the bioleaching efficiency of Cd from soils and decrease the use cost since it is green, acidic and has a high Cd affinity. In this study, different combination modes of cysteine and microbial inoculant were designed to analyze their effects on Cd removal and the soil microbial community through the sequence extraction of Cd fraction and high-throughput sequencing. The results demonstrate that the mixture of cysteine and the microbial inoculant was the best mode for increasing the Cd removal efficiency. And a ratio of cysteine to microbial inoculant of 5 mg:2 mL in a 300 mL volume was the most economically efficient matching. The Cd removal rate increased by 7.7–15.1% in comparison with the microbial inoculant treatment. This could be ascribed to the enhanced removal rate of the exchangeable and carbonate-bound Cd, which achieved 94.6% and 96.1%, respectively. After the treatment, the contents of ammonium nitrogen (NH₃–N), total phosphorus (TP), available potassium (AK), and available phosphorus (AP) in the paddy soils were increased. The treatment of combinations of cysteine and microbial inoculant had an impact on the soil microbial diversity. The relative abundances of Alicyclobacillus, Metallibacterium, and Bacillus were increased in the paddy soils. The microbial metabolic functions, such as replication and repair and amino acid metabolism, were also increased after treatment, which benefitted the microbial survival and adaptation to the environment. The removal of Cd was attributed to the solubilizing, complexing, and ion-exchanging effects of the cysteine, the intra- and extracellular adsorption, and the production of organic acids of functional microorganisms. Moreover, cysteine, as a carbon, nitrogen, and sulfur source, promoted the growth and metabolism of microorganisms to achieve the effect of the synergistic promotion of microbial Cd removal. Therefore, this study underscored the potential of cysteine to enhance the bioremediation performance in Cd-contaminated paddy soils, offering valuable theoretical and technical insights for this field. Full article

Traditional pulp-capping materials like mineral trioxide aggregate (MTA) offer excellent biocompatibility and sealing, but limitations such as prolonged setting time, low bioactivity, and high costs persist. Metformin, with its potential in craniofacial regeneration, could enhance dentin synthesis by targeting pulp cells. This study aimed to: (1) develop a calcium phosphate cement with chitosan (CPCC) with improved physio-mechanical properties; (2) incorporate metformin (CPCC-Met) to assess release; and (3) evaluate human dental pulp stem cells (hDPSCs) response. CPCC was mixed at different powder-to-liquid ratios to evaluate physio-mechanical properties compared to MTA. The optimized CPCC formulation was loaded with 0, 50, 100, and 150 µg of metformin to measure release and assess hDPSCs attachment and proliferation (1, 4, and 7 d) via live/dead imaging and SEM. One-way ANOVA was used for statistical analysis. Results showed CPCC at a 3.25:1 ratio significantly reduced setting time to 41.5 min versus 123 min for MTA (p < 0.05). Metformin release correlated with concentration, and SEM confirmed the presence of a porous, hydroxyapatite-rich surface. Cell viability was consistently high across groups (>93% at 1 d, >95% at 4 d, ≈98% at 7 d), with no significant differences (p > 0.05). These findings suggest that the novel CPCC-Met demonstrates promise as a fast-setting, cost-effective pulp-capping material, offering metformin delivery to enhance dentin repair. Full article

This study investigates the seismic performance of beam-to-column connections in Japanese steel office buildings and evaluates their impact on repair costs as part of practical seismic loss assessment. Repair cost analysis is conducted following FEMA P-58 guidelines, utilizing a probabilistic seismic performance approach. Additionally, this study incorporates the damage and loss of non-structural components, accounting for uncertainties arising from various factors. By applying story loss functions and the Capacity Spectrum Method within the assessment framework of this study, the applicability of these methods in Japanese design practices is validated. A numerical model of a typical steel building is established based on prior experimental data, and a series of numerical analyses are conducted to quantitatively assess variations in building response distribution and fragility resulting from different beam-to-column connection types. Analysis results indicate that, within the range up to maximum strength, differences in connection performance contribute more to variations in fragility than to building response. Component fragility is particularly influenced by connection type and dimensions that affect inter-story drift ratios. This approach highlights the potential cost differences driven by structural specifications and emphasizes the importance of connection-specific fragility in accurately estimating seismic repair costs in practical design. Furthermore, improvements in structural performance have limited effects in reducing non-structural damage, underscoring the necessity of directly enhancing non-structural component performance. Full article

This research aims to apply the displacement-based design method (DBDM) for the seismic design of reinforced concrete-coupled shear wall buildings equipped with energy dissipation dampers. The DBDM offers design simplicity by focusing on structural design based on a target design displacement, where the building converts into a single degree of freedom (SDOF) system. The implementation of dampers aims to reduce repair costs and downtime for buildings following significant seismic events. Two types of dampers are utilized in this study: metallic damper and viscoelastic damper. The DBDM procedure begins with determining the target displacement, which corresponds to the specific story drift ratio of the structural system, using a nonlinear static pushover analysis. For the structural wall system considered in this study, a target drift ratio of 1/250 is selected due to the inherent rigidity of the structure. The effective damping factor is then determined from the average energy absorption, which is based on the ductility factor of each structural member. Additionally, the effective period of the building is obtained from the displacement spectrum of the design-level earthquakes. Finally, the required damper shear capacity for the SDOF system is calculated based on the target deformation and effective stiffness. The design earthquakes are generated from the acceleration response spectrum for Level 2 earthquakes, as specified in the Japanese seismic code, utilizing three different sets of phase information: Kobe, El Centro, and random phase records. The effectiveness of the DBDM is scrutinized through a comparison with results obtained from time history analysis. The results obtained for 6-, 12-, and 18-story RC-coupled shear walls with energy dissipation dampers indicate that the proposed design methodology effectively meets the specified design objectives. Full article

Background/Objectives: Atherosclerosis is a leading cause of death, especially in the developed world, and is marked by chronic arterial inflammation and lipid accumulation. As key players in its progression, monocytes contribute to plaque formation, inflammation, and tissue repair. Understanding monocyte involvement is crucial for developing better therapeutic approaches. The objective of this study is to assess the prognostic value of monocytes for limb-related outcomes following revascularization for complex aortoiliac lesions, thereby emphasizing the central role of monocytes in atherosclerosis. Methods: This prospective cohort study-enrolled patients who had undergone elective aortoiliac revascularization at two hospitals between January 2013 and December 2023. Patients with TASC II type D lesions were included, excluding those with aneurysmal disease. Demographic, clinical, and procedural data were gathered, and patients were monitored for limb-related outcomes. Preoperative complete blood counts were analyzed, and statistical analyses, including multivariable Cox regression, were conducted to identify predictors of major adverse limb events (MALE). Results: The study included 135 patients with a mean age of 62.4 ± 9.20 years and predominantly male (93%). Patients were followed for a median of 61 IQR [55.4–66.6] months. Smoking history (91%) was the most prevalent cardiovascular risk factor. Preoperative monocyte count >0.720 × 10⁹/L was associated with worse 30-day limb-related outcomes (MALE: OR 7.138 95% CI: 1.509–33.764, p = 0.013) and long-term outcomes, including secondary patency (p = 0.03), major amputation (p = 0.04), and MALE (p = 0.039). Cox regression analysis confirmed an elevated monocyte count as an independent predictor of MALE (adjusted hazard ratio 2.149, 95% CI: 1.115–4.144, p = 0.022). Conclusions: This study demonstrated that patients with a higher absolute monocyte count may be more exposed to the risk of MALE in patients with aortoiliac TASC II type D lesions undergoing revascularization, with predictive accuracy in both the short and long term. Additionally, it was an independent predictor of major amputation. This new marker has the potential to serve as a cost-effective and easily available tool for risk stratification, helping identify patients at higher risk of MALE. Full article

To solve the problem of large residual deformation and high repair cost of traditional frame structures after an earthquake, a new type of assembled shuttle-shaped self-centering mild steel energy dissipation brace (ASSSEDB) with stable stiffness, material saving, and easy replacement was proposed. The plastic deformation of mild steel is used to dissipate energy, and the disc spring system provides a reset function. Based on the working mechanism of energy dissipation brace, a restoring force model for the ASSSEDB was established, and then the numerical analysis was carried out by ANSYS to verify the accuracy of the proposed model. The results confirm that the ASSSEDB has stable energy dissipation ability and a resetting function, with a full hysteresis curve. The finite element analysis results align well with the developed restoring force model, and the maximum deviations of initial stiffness and ultimate capacity are, respectively, 1.4% and 2.3%, which indicates that the established restoring force model can provide a theoretical basis for design of the ASSSEDB. Furthermore, the time history analysis was carried out to assess the seismic performance of a six-story steel frame structure using the proposed ASSSEDB. The results show that compared with the steel frame structure with BRBs, the proposed ASSSEDB can decrease the residual deformation of structures by up to 93.41%. The self-centering ratio of the ASSSEDB is crucial in controlling residual deformation of structures, and it is recommended to be greater than 1.0. Full article

Consumer dissatisfaction and damage are increasing worldwide due to the increase in defects caused by the decline in housing quality, and disputes over housing defects are expanding. The number of housing units, a representative standard related to housing quality, is used in Canada, Japan, and Korea. Generally, quality costs increase as the number of housing units increases, and each country’s laws apply stricter management standards. Therefore, the quality is expected to be better as the number of units increases. In 2020, South Korea added a new regulation requiring inspections by a quality inspection team by a public institution only when building housing complexes with more than 300 households. There is a debate about whether this direction of regulation is appropriate. This study examines whether the number of households is being used appropriately as a criterion related to housing quality. It aims to determine whether the limit of 300 households is appropriate for distinguishing housing quality. In addition, since the contractor’s role is vital in housing construction, the contractor’s capabilities and supply–demand relationship were also considered as factors affecting housing quality. The ratio of defect repair costs to construction costs was used as a quality measure for 285 housing complexes in Korea. Generally, the lower the defect repair–construction costs ratio, the better the quality. A comparative study was conducted through a variance analysis on the scale of 300 households and the status of the contractor’s capability, whether they were among the top 10 construction companies with excellent construction performance, and whether a sole contract was made. The results showed that the quality was better in the cases with 300 or more households than in the cases with fewer than 300 households. The quality was better in the cases built by higher-ranking contractors than in those built by other contractors, but there was no difference according to supply-and-demand relationships. The results of the comprehensive analysis indicated that the quality was better when higher-ranking contractors built housing complexes with 300 or more households than when lower-ranking contractors built housing complexes with fewer than 300 households. Therefore, the direction of the Korean regulation requiring quality inspections for housing complexes with more than 300 households is incorrect and should be improved to regulate housing complexes with fewer than 300 households, and of low quality. In addition, the standard of determining housing quality based solely on the number of households should be revised, and the direction should be changed to strengthen quality control and the public supervision of housing built by low-capacity contractors. If the results of this study are utilized with this view in mind, a reasonable system to protect housing consumers will be promoted. Full article

The strengthening, rehabilitation and repair of wooden beams and beams made of wood-based materials are still important scientific and technical issues. This is reflected, among other things, in the number of scientific articles appearing and the involvement of research centres around the world. This is also related to society’s growing belief in the importance of ecological and sustainable development. This article presents an overview of the latest work in this field and the results of our own research on strengthening solid wooden beams with carbon-fibre-reinforced polymer (CFRP) sheets. The tests were carried out on full-size solid beams with nominal dimensions of 70 × 170 × 3300 mm. A 0.333 mm thick CFRP sheet was used for reinforcement. The research analysed various reinforcement configurations and different reinforcement ratios. For the most effective solution, a 46% increase in load capacity, 35% stiffness and 249% ductility were achieved with a reinforcement ratio of 1.7%. Generally, the higher the reinforcement ratio and coverage of the surface of the wood, the higher the strengthening effectiveness. The brittle fracture of wood in the tensile zone for unreinforced beams and the ductile crushing of wood in the compressive zone for reinforced beams were obtained. The most important achievement of this work is the description of the static work of beams in previously unanalysed configurations of strengthening and the confirmation of their effectiveness. The described solutions should extend the life of existing wooden buildings and structures and increase the competitiveness of wooden-based structures. The results indicate that, from the point of view of optimizing the cost of reinforcement, it is crucial to develop cheaper ways of combining wood and composite than to verify different types of fibres. Full article

Quito, the capital of Ecuador, a development pole, has experienced a population growth of 9% in the last five years. The structural system commonly chosen for housing is reinforced concrete frames with flat slabs, embedded beams, and masonry infill. This typology covers approximately 60% of the residential buildings in the city. Adding to the site’s seismic hazard, this fact results in a city with a high seismic risk. The research presented here is carried out within a probabilistic framework to determine the economic consequences of the main structural typology in the city. The methodology defines the seismic hazard by scaling a database of 200 records to the design spectrum. It models the typology to capture the variability between structures with a solid parametric study. Each capacity curve is analyzed through a nonlinear time history analysis using an equivalent one-degree-of-freedom system. The results show an average annual loss ratio of 0.16%. This metric indicates the vulnerability of the typology and the high repair costs of buildings that will be observed in case of an earthquake. The practical implications of these findings are significant as they contribute to urban planning and policy decisions. Finally, it is observed that the probabilistic method used efficiently generates fragility and vulnerability curves, saving computational time and obtaining expected results. Full article

In order to prevent structural damage or high repair costs caused by concrete crack propagation, the use of microbial-induced CaCO₃ precipitation to repair concrete cracks has been a hot topic in recent years. However, due to environmental constraints such as oxygen concentration, the width and depth of repaired cracks are seriously insufficient, which affects the further development of microbial self-healing agents. In this paper, a ternary microbial self-healing agent composed of different proportions of Bacillus pasteurii, Saccharomyces cerevisiae, and Bacillus mucilaginosus was designed, and its crack repair ability was evaluated. When the mixing ratio was 7:1:2, the cell concentration was the highest, the precipitation amount of CaCO₃ was the highest, and the crystallinity of calcite crystal was the highest. Compared to the single microorganism, the mortar specimens with ternary microorganisms had the largest repair area (up to 100%) and the deepest repair depth (CaCO₃ presents at 9–12 mm from the crack surface). This is because when the concrete breaks, all three microorganisms are activated by water, O_2, and CO₂. Saccharomyces cerevisiae and Bacillus mucilaginosus accelerated the growth of Bacillus pasteurii and more mineralized products; CaCO₃ was rapidly formed and quickly filled on the crack surface. When CaCO₃ seals the surface of the crack, the internal Saccharomyces cerevisiae and Bacillus mucilaginosus continue to play a role. Bacillus mucilaginosus can accelerate the dissolution of CO₂ produced by the anaerobic fermentation of Saccharomyces cerevisiae and the hydrolysis of CO₃²⁻, thereby improving the repair of the crack depth direction. Full article

The demand for novel tissue grafting and regenerative wound care biomaterials is growing as traditional options often fall short in biocompatibility, functional integration with human tissue, associated cost(s), and sustainability. Salmon aquaculture generates significant volumes of waste, offering a sustainable opportunity for biomaterial production, particularly in osteo-conduction/-induction, and de novo clinical/surgical bone regeneration. Henceforth, this study explores re-purposing salmon waste through a standardized pre-treatment process that minimizes the biological waste content, followed by a treatment stage to remove proteins, lipids, and other compounds, resulting in a mineral-rich substrate. Herein, we examined various methods—alkaline hydrolysis, calcination, and NaOH hydrolysis—to better identify and determine the most efficient and effective process for producing bio-functional nano-sized hydroxyapatite. Through comprehensive chemical, physical, and biological assessments, including Raman spectroscopy and X-ray diffraction, we also optimized the extraction process. Our modified and innovative alkaline hydrolysis–calcination method yielded salmon-derived hydroxyapatite with a highly crystalline structure, an optimal Ca/P ratio, and excellent biocompatibility. The attractive nano-scale cellular/tissular properties and favorable molecular characteristics, particularly well-suited for bone repair, are comparable to or even surpass those of synthetic, human, bovine, and porcine hydroxyapatite, positioning it as a promising candidate for use in tissue engineering, wound healing, and regenerative medicine indications. Full article