Search Results (1,678)

A hydrogeological study of the shallowest part of the halite nucleus of the Salar de Atacama is presented, focusing on the isotopic variability in δ¹⁸O and δ²H (SMOW) in the brine. It is observed that intensive brine extraction has induced upward vertical flows from the lower aquifer, which presents with a lighter isotopic composition (δ¹⁸O: −0.87‰ to −2.49‰; δ²H: −26.04‰ to −33.25‰), toward the upper aquifer, which has more variable and enriched isotopic values. Among the possible explanations for the lighter isotopic composition of the lower aquifer waters is the influence of paleolakes formed during the wetter periods of the Late Pleistocene and Holocene that recharged the underlying aquifers. The geological structure of the Salar, including faults and the distribution of low-permeability layers, has played a determining role in the system’s hydrodynamics. This study emphasizes the need for continuous and detailed monitoring of the isotopic composition to assess the sustainability of the water resource in response to brine extraction and future climate changes. Additionally, it suggests applying this methodology to other salt flats in the region for a better understanding of hydrogeological processes in arid zones. The research provides an integrative view of the relationship between resource extraction, water management, and ecosystem conservation in one of the most important salars in the world. Full article

Functionally Graded Materials (FGMs) can outperform their homogeneous counterparts. Advances in digitalization technologies, mainly additive manufacturing, have enabled the synthesis of materials with tailored properties and functionalities. Joining dissimilar metals to attain compositional grading is a relatively unexplored research area and holds great promise for engineering applications. Metallurgical challenges may arise; thus, a theoretical critical analysis is presented in this paper. A multidisciplinary methodology is proposed here to unify optimal design, multi-feed Wire-Arc Additive Manufacturing (WAAM), and image-based characterization methods to create structure-specific oriented FGM parts. Topology optimization is used to design FGMs. A beam under pure bending is used to explore the layer-wise FGM concept, which is also analytically validated. The challenges, limitations, and role of WAAM in creating FGM parts are discussed, along with the importance of numerical validation using full-field deformation data. As a result, a conceptual FGM engineering workflow is proposed at this stage, enabling digital data conversion regarding geometry and compositional grading. This is a step forward in processing in silico data, with a view to experimentally producing parts in future. An optimized FGM beam, revealing an optimal layout and a property gradient from iron to copper along the build direction (bottom–up) that significantly reduces the normal pure bending stresses (by 26%), is used as a case study to validate the proposed digital workflow. Full article

The relatively small tensile strength of concrete makes this material particularly vulnerable to cracking. However, the reality is that it is not always possible and practically useful to conduct studies on high-quality sealing cracks due to their inaccessibility or small opening width. Despite the fact that currently there are many technologies for creating self-healing cement composites, one of the most popular is the technology for creating a biologically active self-healing mechanism for concrete. It is based on the process of carbonate ion production by cellular respiration or urease enzymes by bacteria, which results in the precipitation of calcium carbonate in concrete. This technology is environmentally friendly and promising from a scientific and practical point of view. This research focuses on the technology of creating autonomous self-healing concrete using a biological crack-healing mechanism. The research methodology consisted of four main stages, including an analysis of the already conducted global studies, ecological and economic analysis, the prospects and advantages of further studies, as well as a discussion and the conclusions. A total of 257 works from about 10 global databases were analyzed. An overview of the physical, mechanical and operational properties of bioconcrete and their changes is presented, depending on the type of active bacteria and the method of their introduction into the concrete mixture. An analysis of the influence of the automatic addition of various types of bacteria on various properties of self-healing bioconcrete is carried out, and an assessment of the influence of the method of adding bacteria to concrete on the process of crack healing is also given. A comparative analysis of various techniques for creating self-healing bioconcrete was performed from the point of view of technical progress, scientific potential, the methods of application of this technology, and their resulting advantages, considered as the factor impacting on strength and life cycle. The main conditions for a quantitative assessment of the sustainability and the possibility of the industrial implementation of the technology of self-healing bioconcrete are identified and presented. Various techniques aimed at improving the recovery process of such materials are considered. An assessment of the influence of the strength of cement mortar after adding bacteria to it is also given. Images obtained using electron microscopy methods are analyzed in relation to the life cycle of bacteria in mineral deposits of microbiological origin. Current gaps and future research prospects are discussed. Full article

Cell membranes are crucial elements in living organisms, serving as protective barriers and providing structural support for cells. They regulate numerous exchange and communication processes between cells and their environment, including interactions with other cells, tissues, ions, xenobiotics, and drugs. However, the complexity and heterogeneity of cell membranes—comprising two asymmetric layers with varying compositions across different cell types and states (e.g., healthy vs. diseased)—along with the challenges of manipulating real cell membranes represent significant obstacles for in vivo studies. To address these challenges, researchers have developed various methodologies to create model cell membranes or membrane fragments, including mono- or bilayers organized in planar systems. These models facilitate fundamental studies on membrane component interactions as well as the interactions of membrane components with external agents, such as drugs, nanoparticles (NPs), or biomarkers. The applications of model cell membranes have extended beyond basic research, encompassing areas such as biosensing and nanoparticle camouflage to evade immune detection. In this review, we highlight advancements in the engineering of planar model cell membranes, focusing on the nanoarchitectonic tools used for their fabrication. We also discuss approaches for incorporating challenging materials, such as proteins and enzymes, into these models. Finally, we present our view on future perspectives in the field of planar model cell membranes. Full article

As a plasticizer, vegetable oil can improve the compatibility between straw fibers and an asphalt matrix and promote the uniform dispersion of fibers, thereby improving the viscoelastic properties of the composite material. This paper selected three vegetable oils: tall oil, rapeseed oil, and palm wax. Through dynamic shear rheology tests, low-temperature bending beam rheology tests, contact angle tests, and infrared spectroscopy tests, the vegetable-oil-reinforced straw fiber modification was analyzed from different points of view. The research results show that palm wax significantly improves the high-temperature rheological properties of straw-fiber-modified asphalt but has a negative impact on low-temperature properties. Tall oil can most significantly improve the low-temperature rheological properties of straw-fiber-modified asphalt. Rapeseed oil has the most obvious effect in improving the adhesion and water damage resistance of straw-fiber-modified asphalt. In addition, the research shows that all three vegetable oils exist in the modified asphalt in adsorbed form, and no new compounds are generated. These research results provide theoretical guidance value for the application of straw-fiber-modified asphalt pavement in different environments. Full article

Additive manufacturing, better known as 3D printing, is an innovative manufacturing technique which allows the production of parts, with complex and challenging shapes, layer by layer mainly through melting powder particles (metallic, polymeric, or composite) or extruding material in the form of wire, depending on the specific technique. Three-dimensional printing is already widely employed in several sectors, especially aerospace and automotive, although its large-scale use still requires the gain of know-how and to overcome certain limitations related to the production process and high costs. In particular, this innovative technology aims to overtake some of the shortcomings of conventional production methods and to obtain many additional advantages, such as reduction in material consumption and waste production, high level of customisation and automation, environmental sustainability, great design freedom, and reduction in stockpiles. This article aims to give a detailed review of the state of scientific research and progress in the industrial field of metal additive manufacturing, with a detailed view to its potential use in civil engineering and construction. After a comprehensive overview of the current most adopted additive manufacturing techniques, the fundamental printing process parameters to achieve successful results in terms of quality, precision, and strength are debated. Then, the already existing applications of metal 3D printing in the field of construction and civil engineering are widely discussed. Moreover, the strategic potentiality of the use of additive manufacturing both combined with topological optimisation and for the eventual repair of existing structures is presented. It can be stated that the discussed findings led us to conclude that the use of metal additive manufacturing in the building sector is very promising because of the several benefits that this technology is able to offer. Full article

The extraction of bioactive compounds from food by-products is one of the most important research areas for the nutraceutical, pharmaceutical, and food industries. This research aimed to evaluate the efficiency of Ultrasound-Assisted Extraction (UAE) and Microwave-Assisted Extraction (MAE), either alone or in combination, of phenolic compounds from cocoa bean shells (CBSs). These extraction techniques were compared with conventional methods, such as under simple magnetic stirring and the Soxhlet apparatus. After the preliminary characterization of the gross composition of CBSs, the total polyphenol content and radical scavenging of extracts obtained from both raw and defatted cocoa bean shells were investigated. Quantification of the main polyphenolic compounds was then performed by RP-HPLC-DAD, identifying flavonoids and phenolic acids, as well as clovamide. The application of MAE and UAE resulted in a similar or superior extraction of polyphenols when compared with traditional methods; the concentration of individual polyphenols was variously influenced by the extraction methods employed. Combining MAE and UAE at 90 °C yielded the highest antiradical activity of the extract. Spectrophotometric analysis confirmed the presence of high-molecular-weight melanoidins, which were present in higher concentrations in the extracts obtained using MAE and UAE, especially starting from raw material. In conclusion, these results emphasize the efficiency of MAE and UAE techniques in obtaining polyphenol-rich extracts from CBS and confirm this cocoa by-product as a valuable biomass for the recovery of antioxidant compounds, with a view to possible industrial scale-up. Full article

This article studies the influence of solid-phase (type 1 samples) and melt-quenching (type 2 samples) technological modes of obtaining Na₃Fe₂(PO₄)₃ polycrystals on their structures and ion-conducting properties. α-Na₃Fe₂(PO₄)₃ polycrystals of the 1st type are formed predominantly under an isothermal firing regime, and the synthesis of the 2nd type is carried out under sharp temperature gradient conditions, contributing to the formation of glassy precursors possessing a reactive and deformed structure, in which the crystallization of crystallites occurs faster than in precursors obtained under isothermal firing. The elemental composition of α-Na₃Fe₂(PO₄)₃ type 2 polycrystals is maintained within the normal range despite the sharp non-equilibrium thermodynamic conditions of synthesis. The microstructure of the type 1 Na₃Fe₂(PO₄)₃ polycrystals is dominated by chaotically arranged crystallites of medium (7–10 μm) and large (15–35 μm) sizes, while the polycrystals of type 2 are characterized by the preferential formation of small (3–4 μm) and medium (7–10 μm) crystallites, causing uniaxial deformations in their structure, which contribute to a partial increase in their symmetry. The advantage of type 2 polycrystals is that they have higher density and conductivity and are synthesized faster than type 1 samples by a factor of 4. The article also considers the issues of crystallization in a solid-phase precursor from the classical point of view, i.e., the process of the formation of small solid-phase nuclei in the metastable phase and their growth to large particles due to association with small crystallites using phase transitions. Possible variants and models of crystallite growth in Na₃Fe₂(PO₄)₃ polycrystals, as well as distinctive features of crystallization between two types of samples, are discussed. Full article

We present a review of current research on promising flame retardants using specific methods of applying metal–organic frameworks (MOFs) to the highly flammable fibrous surface of cotton fabric. In this review, we initially address the reasons why the search for new flame retardants has becomes critically important in textile finishing, the area responsible for adhering new functionalities to substrates. This addition of characteristics is closely linked to the nature of the fibers, so the reason for the improvement in cotton fabric in relation to flame retardancy is discussed. Furthermore, the development of highly porous nanomaterials that can generate composites with specific functions is described, as well as their application and methods of integration into textile surfaces. Finally, the main candidates for flame retardant functionality in cellulosic materials are identified. It is also hoped that this work will facilitate researchers to develop and formulate new methods of applying nanomaterials to textile substrates, with a view to becoming a reference for new research into the development of adhesion of emerging materials to traditional materials. Full article

The release of Neogene volcanism in the southeastern part of the Iberian Peninsula produced a series of volcanic structures in the form of stratovolcanoes and calderas; however, other materials also accumulated such as large amounts of pyroclastic materials such as cinerites, ashes, and lapilli, which were later altered to form deposits of zeolites and bentonites. This work has focused on an area located on the northern flank of the San José-Los Escullos zeolite deposit, the only one of its kind with industrial capacity in Spain. The main objective of this research is to characterize the zeolite (SZ) of this new area from the mineral, chemical, and technical points of view and establish its possible use as a natural pozzolan. In the first stage, a study of the mineralogical and chemical composition of the selected samples was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and thermogravimetric analysis (TGA); in the second stage, chemical-qualitative and pozzolanicity technical tests were carried out at 8 and 15 days. In addition, a chemical analysis was performed using XRF on the specimens of mortars made with a standardized mixture of Portland cement (PC: 75%) and natural zeolite (SZ: 25%) at the ages of 7, 28, and 90 days. The results of the mineralogical analyses indicated that the samples are made up mainly of mordenite and subordinately by smectite, plagioclase, quartz, halloysite, illite, and muscovite. Qualitative chemical assays indicated a high percentage of reactive silica and reactive CaO and also negligible contents of insoluble residues. The results of the pozzolanicity test indicate that all the samples analyzed behave like natural pozzolans of good quality, increasing their pozzolanic reactivity from 8 to 15 days of testing. Chemical analyses of PC/SZ composite mortar specimens showed how a significant part of SiO₂ and Al₂O₃ are released by zeolite while it absorbs a large part of the SO₃ contained in the cement. The results presented in this research could be of great practical and scientific importance as they indicate the continuation of zeolitic mineralization beyond the limits of the San José-Los Escullos deposit, which would result in an increase in geological reserves and the extension of the useful life of the deposit, which is of vital importance to the local mining industry. Full article

The values of a community with a shared future for mankind include the views of common interests, sustainable development, and global governance. This article will fully consider introducing the value concept of a community with a shared future into the operation and management of dynamic supply chains. Based on the optimal information fusion mechanism of artificial intelligence, this article aims to examine the operation and management of dynamic supply chains within the framework of a community with a shared future for mankind. The core idea is to consider the common interests among enterprises, establish a global collaborative operation concept for upstream, midstream, and downstream enterprises, and achieve the goal of sustainable development. Firstly, a type of composite dynamic supply chain model is considered, in which the total inventory of each node in the supply chain is further subdivided into raw material inventory and finished product inventory. At the same time, we have considered factors such as the signing of procurement contracts between core enterprises and upstream enterprises, as well as the signing of supply contracts between core enterprises and downstream enterprises. Secondly, the static and dynamic monitoring information of the enterprise has been established. We use steady-state Kalman filtering theory to obtain dynamic reference signals for upstream enterprises, core enterprises, and downstream enterprises. Based on the optimal information fusion processing mechanism of artificial intelligence, the coefficient weighting method is used to obtain the optimal fusion signals of upstream enterprises, core enterprises, and downstream enterprises. Once again, through high-quality switching strategies, enterprises can achieve in-order switching, improve production efficiency, reduce downtime, enhance their competitiveness and responsiveness, and transform the dynamic supply chain, including order switching, into a discrete-time linear switching system for processing. Fourthly, sufficient conditions, robustness analysis results, and inventory control criteria for the solvability of dynamic supply chain H∞ with order switching are provided. Finally, data analysis is conducted using historical order information from three fruit companies to verify the validity and feasibility of the conclusions in this article and to improve the performance of the dynamic supply chain system. The research findings of this article enrich the exploration of the operation and management of dynamic supply chains and the construction of a community with a shared future for mankind. Full article

The increasing amount of sewage sludge produced demands new methods of its management to minimize socioeconomic and environmental problems related to its current treatment. An effective solution may be the thermochemical conversion of sewage sludge through gasification. First, the most known sewage sludge gasification processes are presented along with the challenges that they face. Then the detailed characteristics of sewage sludge are discussed from the point of view of its use in the gasification process, as well as research on the kinetics of gasification of sewage sludge char using various models. As scientific reports on sewage sludge gasification focus on the influence of process parameters on gas yield and composition (especially H₂ and tar content), the main part of the work is devoted to the discussion on the influence of temperature, type, and amount of the gasifying agent and the presence of a catalyst on these parameters. Moreover, the co-gasification of sewage sludge as well as advanced gasification methods, i.e., supercritical water gasification and plasma gasification, are analyzed. Finally, the possibilities of utilization of sewage sludge gasification process by-products were discussed and the impact of the process on the environment was assessed. The review concludes with indications of directions for further research. Full article

The process of stone formation in the human body remains incompletely understood, which requires clinical and laboratory studies and the formulation of a new endogenous, nanotechnological concept of the mechanism of origin and formation of crystallization centers. Previously, the mechanism of sialolithiasis was considered a congenital disease associated with the pathology of the ducts in the structure of the glands themselves. To date, such morphological changes of congenital nature can be considered from the position of the intrauterine formation of endogenous bacterial infections complicated by the migration of antigenic structures initiating the formation of crystallization centers. The present work is devoted to the study of the morphology and composition of stones obtained as a result of surgical interventions for sialolithiasis. Presumably, nanoparticles of metals and other chemical compounds can be structural components of crystallization centers or incorporated into the conditions of chronic endogenous inflammation and the composition of antigenic structures, in complexes with protein and bacterial components. X-ray microtomography, X-ray fluorescence analysis, scanning transmission electron microscopy and microanalysis, mass spectrometry, and Raman spectroscopy were used to study the pathogenesis of stone formation. Immunoglobulins (Igs) of classes A and G, as well as nanoparticles of metals Pb, Fe, Cr, and Mo, were found in the internal structure of the stones. The complex of antigenic structures was an ovoid calcified layered matrix of polyvid microbial biofilms, with the inclusion of metal nanoparticles and chemical elements, as well as immunoglobulins. The obtained results of clinical and laboratory studies allow us to broaden the view on the pathogenesis of stone formation and suggest that the occurrence of the calcification of antigenic structures may be associated with the formation of IgG4-associated disease. Full article

In this study, a novel supramolecular composite, “photogels”, was synthesized by mixing of cysteine–silver sol (CSS) and methylene blue (MB). A complex of modern physico-chemical methods of analysis such as viscosimetry, UV spectroscopy, dynamic and electrophoretic light scattering, scanning electron microscopy and energy-dispersive X-ray spectroscopy showed that MB molecules are uniformly localized mainly in the space between fibers of the gel-network formed by CSS particles. Molecules of the dye also bind with the surface of CSS particles by non-covalent interactions. This fact is reflected in the appearance of a synergistic anticancer effect of gels against human squamous cell carcinoma even in the absence of light irradiation. A mild toxic influence of hydrogels was observed in normal keratinocyte cells. Photodynamic exposure significantly increased gel activity, and there remained a synergistic effect. The study of free-radical oxidation in cells has shown that gels are not only capable of generating reactive oxygen species, but also have other targets of action. Flow cytometric analysis allowed us to find out that obtained hydrogels caused cell cycle arrest both without irradiation and with light exposure. The obtained gels are of considerable interest both from the point of view of academics and applied science, for example, in the photodynamic therapy of superficial neoplasms. Full article

Yarrow (Achillea millefolium L., AM) is a widely used medicinal plant, with its essential oil highly valued in the cosmetic industry. In view of the numerous biological effects, however, microencapsulation, due to its ability to protect sensitive constituents, transform liquids into solid-state material, and provide modification of release kinetics, might open up new possibilities for the biomedical utilization of yarrow essential oil (AMO). In the current work, yarrow plantation was established by its propagation from spontaneous flora. Following the steam distillation of aerial parts, the chemical composition of the essential oil was determined by GC-MS analysis and compared with two commercial samples. This study concludes that Achillea millefolium L. from this region, given the environmental conditions, produces high-azulene-content essential oil. Furthermore, microencapsulation of AMO was successfully performed by complex coacervation into gelatin (GE) and gum arabic (GA) based core–shell microcapsules (MCs). According to the optical microscopic investigation, the particle sizes of the formed polynucleated microcapsules ranged from 14 to 132 µm, with an average of 47 µm. The assessment of morphology by SEM analysis of the freeze-dried form revealed a sponge-like character with embedded circular structures. The microencapsulation was confirmed by FT-IR spectroscopy and differential scanning calorimetry (DSC), while an encapsulation efficiency of 87.6% was determined by UV spectroscopy. GC-MS analysis revealed that microencapsulation preserves the key components of the essential oil. It was concluded that AMO can be effectively processed by complex coacervation followed by freeze-drying into solid-state material for new applications. Full article