Search Results (701)

The priming effect (PE), a microbially mediated process, critically regulates the balance between carbon sequestration and mineralization. This study used soils from different soil depths (0–20 cm, 20–40 cm, and 40–60 cm) under Picea schrenkiana forest in the Tianshan Mountains as the research object. An indoor incubation experiment was conducted by adding three concentrations (1% SOC, 2% SOC, and 3% SOC) of ¹³C-labelled glucose. We applied ¹³C isotope probe-phospholipid fatty acid (PLFA-SIP) technology to investigate the influence of readily labile organic carbon inputs on soil priming effect (PE), microbial community shifts at various depths, and the mechanisms underlying soil PE. The results indicated that the addition of ¹³C-labeled glucose accelerated the mineralization of soil organic carbon (SOC); CO₂ emissions were highest in the 0–20 cm soil layer and decreased trend with increasing soil depth, with significant differences observed across different soil layers (p < 0.05). Soil depth had a positive direct effect on the cumulative priming effect (CPE); however, it showed negative indirect effects through physico-chemical properties and microbial biomass. The CPE of the 0–20 cm soil layer was significantly positively correlated with ¹³C-Gram-positive bacteria, ¹³C-Gram-negative bacteria, and ¹³C-actinomycetes. The CPE of the 20–40 cm and 40–60 cm soil layers exhibited a significant positive correlation with cumulative mineralization (CM) and microbial biomass carbon (MBC). Glucose addition had the largest and most significant positive effect on the CPE. Glucose addition positively affected PLFAs and particularly microbial biomass. This study provides valuable insights into the dynamics of soil carbon pools at varying depths following glucose application, advancing the understanding of forest soil carbon sequestration. Full article

During a volcanic eruption, a large volume of pyroclastic material can be deposited on the roads and roofs of the urban areas near volcanoes. The use of volcanic ash as an additive for the manufacture of bricks provides a solution to the disposal of part of this natural residue and reduces the depletion of a non-renewable natural resource, clayey soil, which brings some environmental and economic advantages. The pore system, compactness, uniaxial compression strength, thermal conductivity, color and durability of bricks without and with the addition of volcanic ash were evaluated through hydric tests, mercury intrusion porosimetry, ultrasound, uniaxial compression tests, IR thermography, spectrophotometry and salt crystallization tests. The purpose of this research is to determine the feasibility of adding 10, 20 and 30% by weight of volcanic ash from La Palma (Canary Islands, Spain) in two grain sizes to produce bricks fired at 800, 950 and 1100 °C. The novelty of this study is to use two sizes of volcanic ash and fire the samples at 1100 °C, which is close to the liquidus temperature of basaltic magmas and allows a high degree of interaction between the volcanic ash and the brick matrix. The addition of fine volcanic ash was found to decrease the porosity of the bricks, although the use of high percentages of coarse volcanic ash resulted in bricks with almost the same porosity as the control samples. The volcanic ash acted as a filler, reducing the number of small pores in the bricks. The presence of vesicles in the volcanic ash reduced the compressive strength and the compactness of the bricks with additives. This reduction was more evident in bricks manufactured with 30% of coarse volcanic ash and fired at 800 and 950 °C, although they still reached the minimum resistance required for their use in construction. No significant differences in thermal conductivity were noticed between the bricks with and without volcanic ash additives, which is crucial in terms of energy savings and the construction of sustainable buildings. At 1100 °C the volcanic ash changed in color from black to red. As a result, the additive blended in better with the matrix of bricks fired at 1100 °C than in those fired at 800 and 950 °C. The bricks with and without volcanic ash and fired at 1100 °C remained intact after the salt crystallization tests. Less salt crystallized in the bricks with volcanic ash and fired at 800 and 950 °C than in the samples without additives, although their low compressive strength made them susceptible to decay. Full article

The storage of sewage sludge in landfills is still the primary method of their disposal in many countries. Therefore, finding sustainable solutions for the reuse of this waste is an important issue to be addressed. This paper presents the results of research on processing sewage sludge generated at the wastewater treatment plants of Almaty, Kazakhstan, for use in the manufacturing of ceramic bricks. The chemical composition of the sewage sludge was determined, showing the presence of 35.7% silicon dioxide, 7.3% aluminum oxide, 11.2% iron oxide, and 10.6% calcium oxide. Experimental studies established that adding sewage sludge to clay reduces the compressive strength of ceramic bricks while increasing their flexural strength. Furthermore, as the proportion of sewage sludge in the clay mixture increases, the average density of the ceramic bricks decreases, while water absorption increases. It was also found that ceramic bricks made from a mixture of 90% clay and 10% sewage sludge demonstrated the best physico-mechanical properties. This composition showed increased flexural strength and a simultaneous reduction in the average density by 15.4%, indicating the improved structural quality of the manufactured bricks. Full article

A major breakthrough in environmentally friendly building materials is the development of sustainable unfired clay bricks including alumina waste produced during liquid nitrogen generation. Though used extensively, conventional fired clay bricks require energy-intensive manufacturing techniques that produce significant amounts of CO₂ and aggravate environmental damage. By removing the need for high-temperature firing and allowing for the valorization of industrial byproducts including alumina waste and lateritic soil, unfired clay bricks offer a reasonable low-carbon alternative. High silica and alumina contents define the alumina waste, which shows pozzolanic reactivity, thus improving the physicomechanical performance of the bricks. With alumina waste substituting 0–8.57% of the cement content, seven different formulations showed improvements in compressive strength, reduced water absorption, and optimal thermal conductivity. Especially, the mechanical performance was much enhanced with alumina waste inclusion up to 30%, without sacrificing thermal insulation capacity or moisture resistance. Further supporting the environmental and financial sustainability of the suggested brick compositions is the economic viability of using industrial waste and regionally derived soils. A comparative analysis of the conventional fired bricks shows that the unfired substitutes have a much lower environmental impact and show better mechanical properties, including greater compressive strength and modulus of rupture. These results support the more general goals of circular economy systems and low-carbon urban development by highlighting the feasibility of including alumina waste and lateritic soil into sustainable building materials. Using such waste-derived inputs in building fits world initiatives to lower resource consumption, lower greenhouse gas emissions, and build strong infrastructure systems. Full article

This paper presents the results of testing the insulation performance of geopolymers based on fly ashes with the addition of waste broken glass. The waste glass was dried and ground to a maximum of 1 mm grain size. The proportions of broken glass in the total binder’s mass were 0%, 10%, 20%, and 30%. Sodium hydroxide and sodium silicate were the activators of the alkaline reaction. The obtained geopolymer materials were characterised by determining the basic physico-mechanical properties. The chemical composition, density, and thermal conductivity coefficient were determined. The mechanical performance, including compressive and flexural strength, was investigated after 28 days of curing. The morphological analysis was also carried out using microphotographs obtained from optical and scanning microscopes. A significant effect of the waste glass on the tested geopolymers’ mechanical performance was observed. Proportions of 10% and 20% broken glass in the binder led to more than a four-fold increase in the compressive strength and a two-fold increase in the flexural strength compared to the geopolymer without the waste glass. All tested geopolymers had excellent insulation ability compared to the reference mortar (more than 80% higher than cement mortar). However, the problem is potential alkali–silica reaction, which can occur when the waste glass content is high. Full article

Aqueous solutions are not homogeneous and could be considered supramolecular systems. They can emit electromagnetic waves. Electromagnetic emission from one supramolecular system (“source”) can be received by another supramolecular system (“receiver”) without direct contact (distantly). This process represents a transfer of a “molecular signal” and causes changes in conformation and symmetry of the “receiver”. The aim of the current work is to theoretically describe such changes primarily using a solution of the chiral protein interferon-gamma (IFNγ) as an example. We provide theoretical evidence that supramolecular systems of highly diluted (HD) aqueous solutions formed by self-assembly after mechanical activation generate a stronger molecular signal compared to non-activated solutions, due to their higher energy-saturated state. Additionally, molecular signals cause supramolecular systems with complex (including chiral) structures to undergo easier changes in conformation and symmetry compared to simpler systems, enhancing their biological activity. Using statistical physics, we obtained the parameter Ic, characterizing the magnitude of conformational and symmetry changes in supramolecular (including chiral) systems caused by molecular signals. In quantum information science, there is an analogue of the parameter Ic, which characterizes the entanglement depth of quantum systems. This study contributes to the understanding of the physico-chemical basis of distant molecular interactions and opens up new possibilities for controlling the properties of complex biological and chemical systems. Full article

Despite its broad application due to its affordability, biodegradability, and natural antimicrobial and antioxidant activities, chitosan (CS) still exhibits limitations in mechanical strength and barrier effectiveness. Owing to its unique chemical characteristics, itaconic acid (IT) presents potential as a compatibilizing agent in polymeric blend formulations. Biodegradable polymers composed of chitosan (CS), itaconic acid (IT), and starch (S) were synthesized using two polymerization methods. The first method involved grafting IT onto CS at varying ratios of IT (4%, 6%, and 8% wt.), using 1% v/v acetic acid/water as the solvent and potassium persulfate as the initiator. In the second approach, starch (S) was blended with the copolymer P(CS-g-IT) at concentrations of 1%, 3%, and 5%, utilizing water as the solvent and glacial acetic acid as a catalyst. The resulting biodegradable films underwent characterization through FTIR, TGA, SEM, and mechanical property analysis. To further explore the effects of combining IT, starch, and carbon black, the blends, referred to as P[(CS-g-IT)-b-S], were also loaded with carbon black. This allowed for the evaluation of the materials’ physicomechanical properties, such as viscosity, tensile strength, elongation, and contact angle. The findings demonstrated that the presence of IT, starch, and carbon black collectively improved the films’ mechanical performance, physical traits, and biodegradability. Among the samples, the blended copolymer with 1% starch exhibited the highest mechanical properties, followed by the grafted copolymer with 8% IT and the blended copolymer mixed with carbon black at 7%. In contrast, the blended copolymer with 5% starch showed the highest hydrophilicity and the shortest degradation time compared to the grafted copolymer with 8% IT and the blended copolymer mixed with 7% carbon black. Full article

This study presents a comprehensive material characterization, including physical, hygric, and mechanical properties, of historical ceramic bricks to enhance the understanding of heritage masonry structures and support the effective planning of conservation interventions. The primary objective is to systematize the knowledge of constituent materials in brick walls from different historical periods and to evaluate the compatibility of modern repair materials with the original fabric. To this end, a comprehensive experimental protocol was employed, which included the determination of fundamental physical properties such as density, water absorption, and sorptivity. Additionally, chemical and thermogravimetric analyses were performed, followed by freeze–thaw resistance testing and compressive strength measurements. Microstructural analysis was conducted using mercury intrusion porosimetry. The results identified the pore size ranges most susceptible to frost-induced degradation and revealed correlations between the physical, hygric, and mechanical properties of the tested ceramic materials. These findings provide essential data on the physico-mechanical characteristics of historical bricks, establishing a basis for the informed selection of compatible materials in conservation practice. Full article

The transformative trajectory of urban development in the contemporary era has engendered a substantial escalation in construction waste generation, particularly in China, where it constitutes approximately 40% of the total solid waste stream. Traditional landfill disposal methodologies pose formidable ecological challenges, encompassing soil contamination, groundwater pollution, and significant greenhouse gas emissions. Furthermore, the unsustainable exploitation of natural sandstone resources undermines energy security and disrupts ecological balance. In response to these pressing issues, an array of scholars and researchers have embarked on an exploratory endeavor to devise innovative strategies for the valorization of construction waste. Among these strategies, the conversion of waste into recycled aggregates has emerged as a particularly promising pathway. However, the practical deployment of recycled aggregates within the construction industry is impeded by their inherent physico-mechanical properties, such as heightened water absorption capacity and diminished compressive strength. To surmount these obstacles, a multitude of enhancement techniques, spanning physical, chemical, and thermal treatments, have been devised and refined. This paper undertakes a comprehensive examination of the historical evolution, recycling methodologies, and enhancement strategies pertinent to recycled aggregates. It critically evaluates the efficacy, cost–benefit analyses, and environmental ramifications of these techniques, while elucidating the microstructural and physicochemical disparities between recycled and natural aggregates. Furthermore, it identifies pivotal research gaps and prospective avenues for future inquiry, underscoring the imperative for collaborative endeavors aimed at developing cost-effective and environmentally benign enhancement techniques that adhere to the stringent standards of contemporary construction practices, thereby addressing the intertwined challenges of waste management and resource scarcity. Full article

This study presents the results of investigations into the properties of a composite made from the commercial biopolymer with varying concentrations of ground coffee husks (CH) at 10, 30, and 50 wt%. Thermal, thermomechanical, physical, and mechanical properties were determined for the composites. Results indicate that the inclusion of CH into the polymer matrix significantly enhances the thermomechanical properties of the obtained composites, particularly in terms of storage modulus at 30 °C. The addition of coffee filler did not alter the characteristic thermal curves. Still, it reduced the thermal resistance of the composites, lowering the degradation temperature by approximately 40 °C compared to the pure polymer. Furthermore, the incorporation of CH introduced an additional stage of mass loss on the thermogravimetric curves, associated with the thermal decomposition of CH. The physico-mechanical properties of the composite depend on the content of the filler. Increasing the coffee content increases the dynamics of water absorption by the composite. It also increases the composite’s stiffness while reducing its tensile and flexural strength. The obtained results suggest that biopolymer-based composites filled with ground CH can be effectively used for manufacturing biodegradable products, with the moisture diffusion behavior indicating susceptibility to degradation that is modulated by the CH content. Full article

Cerium dioxide nanoparticles (CeO₂-NPs) are increasingly used in various industrial applications, leading to their inevitable release into the environment including the soil ecosystem. In soil, CeO₂-NPs are taken up by plants, translocated, and accumulated in plant tissues. Within plant tissues, CeO₂-NPs have been shown to interfere with critical metabolic pathways, which may affect plant health and productivity. Moreover, their presence in soil can influence soil physico-chemical and biological properties, including microbial communities within the rhizosphere, where they can alter microbial physiology, diversity, and enzymatic activities. These interactions raise concerns about the potential disruption of plant–microbe symbiosis essential for plant nutrition and soil health. Despite these challenges, CeO₂-NPs hold potential as tools for enhancing crop productivity and resilience to stress, such as drought or heavy metal contamination. However, understanding the balance between their beneficial and harmful effects is crucial for their safe application in agriculture. To date, the overall impact of CeO₂-NPs on soil -plant system and the underlying mechanism remains unclear. Therefore, this review analyses the recent research findings to provide a comprehensive understanding of the fate of CeO₂-NPs in soil–plant systems and the implications for soil health, plant growth, and agricultural productivity. As the current research is limited by inconsistent findings, often due to variations in experimental conditions, it is essential to study CeO₂-NPs under more ecologically relevant settings. This review further emphasizes the need for future research to assess the long-term environmental impacts of CeO₂-NPs in soil–plant systems and to develop guidelines for their responsible use in sustainable agriculture. Full article

The paper is devoted to the plasticization mechanisms of alkali-activated cement system Na₂O-CaO-Al₂O₃-SiO₂-H₂O. The fundamentals and basic factors determining the effectiveness of plasticizing surfactants for alkali-activated cement materials are discussed. The factors under consideration in the study were alkali-activated cement basicity (the content of granulated blast furnace slag), the anion of the alkaline component or activator, and the degree of dispersing of the cement particles in the system. The action effect of plasticizers was determined by finding the interrelation between the stability of its molecular structure, degree of adsorption, and molecular weight depending on mentioned basic factors. A systematic approach to the systematization of surfactants and their choice to be taken into consideration to control technology-related and physico-mechanical properties of alkali-activated cement-based heavyweight concretes, building mortars, and lightened grouts has been proposed. Full article

This paper presents the effect of wood treatment with cellulose nanofibers on its parameters. The wettability, color changes (also after UV+IR radiation), equilibrium moisture content and mechanical parameters of wood treated with cellulose nanofibers (CNF) in three concentrations (0.5, 1 and 2%) were determined. Wood treatment with CNF increased the wettability of its surface, as evidenced by lower values of the contact angle (24.3–56.3 degrees) compared to untreated wood (98.3 degrees). The SEM images indicated the formation of cellulose nanofiber networks on the wood surface, especially in the case of 2% CNF-treated wood, which formed a well-adhered and homogenous film. Wood treated with 0.5% CNF showed a lower total color change (∆E*) value (1.9) after aging compared to untreated wood (2.9), indicating that the color changes in the treated wood were very small and recognizable only to an experienced observer, while the color differences in the control wood were recognizable to an inexperienced observer. Furthermore, CNF showed no negative effect on the strength parameters of the treated wood and only slightly affected the equilibrium moisture content for both sorption phases over the entire relative humidity range compared to control samples. The results prove the effective use of cellulose nanofibers in wood treatment, which can be an ecological and non-toxic component of wood protection systems. Full article

Fly ash aggregates (FAAs) were synthesized via a hydrothermal process, involving the reaction of fly ash and cement at 180 °C under saturated steam conditions. A thorough examination was carried out to evaluate the impact of cement content on the physico-mechanical properties of the resulting FAAs. A comprehensive exploration was undertaken to decipher the mechanisms by which cement modulates the cylinder compressive strength of FAAs, encompassing mineralogical composition, microstructure, insoluble residue content, and loss on ignition. As the cement proportion increased, a concomitant rise in the amount of hydration products was observed, leading to an enhanced filling effect. This, subsequently, resulted in reduced water absorption and increased apparent density of the FAAs. The augmented filling effect of hydration products contributed to a gradual elevation in the cylinder compressive strength of FAAs as cement content escalated from 5 to 35 wt%. However, a significant transition occurred when cement content surpassed 35%, reaching 35–45 wt%. Within this range, the micro-aggregate effect was diminished, causing a decrease in cylinder compressive strength. The optimal equilibrium between the filling effect and micro-aggregate effect was attained at 35 wt% cement content, where the cylinder compressive strength of FAAs reached its peak value of 18.5 MPa. This research is expected to provide a feasible approach for solid waste reduction, with a particular emphasis on the utilization of fly ash. Full article

The bio-fabrication of sustainable mycelium-based composites (MBCs) from renewable plant by-products offers a promising approach to reducing resource depletion and supporting the transition to a circular economy. In this research, MBCs were obtained by cultivating Ganoderma resinaceum GA1M on essential oils and agricultural by-products: hexane-extracted rose flowers (HERF), steam-distilled lavender straw (SDLS), wheat straw (WS), and pine sawdust (PS), used as single or mixed substrates. The basic physical and mechanical properties revealed that MBCs perform comparably to high-efficiency thermal insulating and conventional construction materials. The relatively low apparent density, ranging from 110 kg/m³ for WS-based to 250 kg/m³ for HERF-based composites, results in thermal conductivity values between 0.043 W/mK and 0.054 W/mK. Compression stress (40–180 kPa at 10% deformation) also revealed the good performance of the composites. The MBCs had high water absorption due to open porosity, necessitating further optimization to reduce hydrophilicity and meet intended use requirements. An aerobic biodegradation test using respirometry indicated ongoing microbial decomposition for all tested bio-composites. Notably, composites from mixed HERF and WS (50:50) showed the most rapid degradation, achieving over 46% of theoretical oxygen consumption for complete mineralization. The practical applications of MBCs depend on achieving a balance between biodegradability and stability. Full article