Search Results (3,562)

Background: The issue of renewable energy (RE) source intermittency, such as wind and solar, along with the geographically uneven distribution of the global RE potential, makes it imperative to establish an energy transport medium to balance the energy demand and supply areas. A promising energy vector to address this situation is hydrogen, which is considered a clean energy carrier for various mobile and portable applications. Unfortunately, at standard pressure and temperature, its energy content per volume is very low (0.01 kJ/L). This necessitates alternative storage technologies to achieve reasonable capacities and enable economically viable long-distance transportation. Among the hydrogen storage technologies using chemical methods, liquid organic hydrogen carrier (LOHC) systems are considered a promising solution. They can be easily managed under ambient conditions, the H₂ storage/release processes are carbon-free, and the carrier liquid is reusable. However, the evolution of the proposals from the carrier liquid type and catalyst elemental composition point of view is scarcely studied, considering that both are critical in the performance of the system (operational parameters, kinetic of the reactions, gravimetric hydrogen content, and others) and impact in the final cost of the technology deployed. The latter is due to the use of the Pt group elements (PGEs) in the catalyst that, for example, have a high demand in the hydrogen production sector, particularly for polymer electrolyte membrane (PEM) water electrolysis. With that in mind, our objective was to examine the evolution and the focus of the research in recent years related to proposals of LOHCs and catalysts for hydrogenation and dehydrogenation reactions in LOHC systems which can be useful in defining routes/strategies for new participants interested in becoming involved in the development of this technology. Data sources: For this systematic review, we searched the SCOPUS database and forward and backward citations for studies published in the database between January 2011 and December 2022. Eligibility criteria: The criteria include articles which assessed or studied the effect of the type of catalyst, type of organic liquid, reactor design(s)/configuration(s), and modification of the reactor operational parameters, among others, over the performance of the LOHC system (de/hydrogenation reaction(s)). Data extraction and analysis: The relevant data from each reviewed study were collected and organized into a pre-designed table on an Excel spreadsheet, categorized by reference, year, carrier organic liquid, reaction (hydrogenation and/or dehydrogenation), investigated catalyst, and primary catalyst element. For processing the data obtained from the selected scientific publications, the data analysis software Orbit Intellixir was employed. Results: For the study, 233 studies were included. For the liquid carrier side, benzyltoluene and carbazole dominate the research strategies. Meanwhile, platinum (Pt) and palladium (Pd) are the most employed catalysts for dehydrogenation reactions, while ruthenium (Ru) is preferred for hydrogenation reactions. Conclusions: From the investigated liquid carrier, those based on benzyltoluene and carbazole together account for over 50% of the total scientific publications. Proposals based on indole, biphenyl, cyclohexane, and cyclohexyl could be considered to be emerging within the time considered in this review, and, therefore, should be monitored for their evolution. A great activity was detected in the development of catalysts oriented toward the dehydrogenation reaction, because this reaction requires high temperatures and presents slow H₂ release kinetics, conditioning the success of the implementation of the technology. Finally, from the perspective of the catalyst composition (monometallic and/or bimetallic), it was identified that, for the dehydrogenation reaction, the most used elements are platinum (Pt) and palladium (Pd), while, for the hydrogenation reaction, ruthenium (Ru) widely leads its use in the different catalyst designs. Therefore, the near-term initiatives driving progress in this field are expected to focus on the development of new or improved catalysts for the dehydrogenation reaction of organic liquids based on benzyltoluene and carbazole. Full article

High-pressure processing (HPP) is a promising technology for increasing the shelf life of food, with minimal effects on the nutritional or sensory quality. However, there has been a concern that high-oil-content foods may protect food pathogens in HPP, and that HPP can affect the quality of lipids. We inoculated Listeria monocytogenes and Salmonella Typhimurium into 34% and 54% oil-content pesto sauce, processed them either with HPP (600 MPa, 4 min) or thermal processing (82 °C, 5 min), and analyzed bacteria counts, pH, GC-MS (Terpene compounds), the time–kill kinetic study, and lipid oxidation value for 60 days in refrigerating storage (5 ± 2 °C). Our findings show that HPP significantly reduced the number of bacteria (more than 4-log) compared to thermal processing or non-processing. Additionally, we discovered terpene compounds (highest-level terpene: L-linalool, eugenol, and 1,8-cineol) in pesto oil that exhibit antimicrobial activity. Different oil content did not have any significant effect on bacteria levels. Regarding chemical results, all samples were of acceptable quality, and the processes did not show any negative effect on lipid oxidation (Peroxide and P-Anisidine value under 10 meq per kilogram of oil). In conclusion, our study indicates that HPP is a suitable method for high-oil-content pesto sauce. In addition, functional compounds naturally present in pesto may contribute to maintaining its microbial and chemical quality. Full article

Today, bio-sourced materials represent an important technological field of study, as they could sink atmospheric carbon dioxide into buildings. Little-processed construction materials would also reduce the environmental impact of the construction sector, which emitted more than 2.9 Mt of CO₂ in 2020. Hemp-lime is a material that meets both these requirements. It is an insulating mix that can take different forms and be used in various parts of a building. The challenge is providing it with enough mechanical strength to make it loadbearing, at least to some extent. This research focuses on the construction and monitoring of a pointed arch, based on a previous experimental hemp-lime construction at Cardiff University in 2009, under the direction of architect David Lea. Since 2022, such an experiment on a possible loadbearing hemp-lime mix is being repeated at the Politecnico di Torino as part of a wider project called “experimental pavilions of vegetarian architecture”. The design and numerical analysis of the Cardiff prototype led to the modification of both the geometry and the composition of the mix using only pozzolanic air lime as the binder. The construction of the arch ended in December 2023. Observing the thermo-hygrometric conditions of this hemp-lime mix once in place is the main purpose of this article. A strong correlation is revealed between outdoor conditions with temperature and moisture content in the core of the arch. Building a full-size outdoor prototype allows for the avoidance of mathematical correction to the results obtained and allows the assessment the mix’s resistance in relation with environmental conditions. Due to some similarities of nature and function between lime and cement, many studies of lime mixes do not exceed a duration of 28 days, which cannot be considered the appropriate observation time for its curing. Therefore, we analysed this lime-based material for around 6 months, according to its own temporality and chemical kinetics. Through continuous monitoring at 10-min intervals, it was possible to highlight several significant aspects of rammed hemp-lime. The results show that the temperature within the mix is influenced by the outside temperature, but the sun exposure of certain areas drives up the corresponding temperature values more rapidly. Furthermore, while the absorption of water in the form of vapour is very rapid, desorption takes longer, as does re-establish a balance between the material and its context. Finally, solar exposure affects particularly 30-cm-thick elements, while elements that are 60 cm thick are not affected in the short term but only in long-term exposure conditions like season changes. Full article

Background: The regulation of cellular proliferation and genomic integrity is controlled by complex surveillance mechanisms known as cell cycle checkpoints. Disruptions in these checkpoints can lead to developmental defects and tumorigenesis. Methods: To better understand these mechanisms, computational modeling has been employed, resulting in a dataset of 414 mathematical models in the BioModels database. These models vary significantly in detail and simulated processes, necessitating a robust analytical approach. Results: In this study, we apply the chemical organization theory (COT) to these models to gain insights into their dynamic behaviors. COT, which handles both ordinary and partial differential equations (ODEs and PDEs), is utilized to analyze the compartmentalized structures of these models. COT’s framework allows for the examination of persistent subsystems within these models, even when detailed kinetic parameters are unavailable. By computing and analyzing the lattice of organizations, we can compare and rank models based on their structural features and dynamic behavior. Conclusions: Our application of the COT reveals that models with compartmentalized organizations exhibit distinctive structural features that facilitate the understanding of phenomena such as periodicity in the cell cycle. This approach provides valuable insights into the dynamics of cell cycle control mechanisms, refining existing models and potentially guiding future research in this area. Full article

Nowadays, emissions from internal combustion engines are a relevant topic of investigation, taking into account the continuous reduction of emission limits imposed by environmental regulatory agencies around the world, obviously as the result of earnest studies that have pointed out the impact on the human health of high levels of contaminants released into the environment. Over recent years, the use of biofuels has contributed to attenuating this environmental issue; however, new problems have been raised, such as NOx emissions tend to increase as the biofuel percentage in the fuel used in engines increases. In this research, the emissions of a compression ignition internal combustion engine modeled as a variable volume reactor with homogeneous combustion were numerically investigated. To analyze the combustion process, a detailed kinetics model tailored specifically for this purpose was used. The kinetics model comprised 30,975 chemical reactions involving 691 chemical species. Mixtures of fuel surrogates were then created to represent the fuel used in the Brazilian fuel marketplace, involving (i) fossil diesel—“diesel A”, (ii) soybean diesel—“biodiesel”, and (iii) hydrotreated vegetable oil— “HVO”. Surrogate species were then selected for each of the aforementioned fuels, and blends of those surrogates were then proposed as mixture M1 (diesel A:biodiesel:HVO—90:10:0), mixture M2 (diesel A:biodiesel:HVO—85:15:0), and mixture M3 (diesel A:biodiesel:HVO—80:15:5). The species allowed in the kinetics model included all the fuel surrogates used in this research as well as the target emission species of this study: total hydrocarbons, non-methane hydrocarbons, carbon monoxide, methane, nitrogen oxides, carbon dioxide, soot, and soot precursors. When compared to experimental trends of emissions available in the literature, it was observed that, for all the proposed fuel surrogates blends, the numerical approach performed in this research was able to capture qualitative trends for engine power and the target emissions in the whole ranges of engine speeds and engine loads, despite the CO and NOx emissions at specific engine speeds and loads. Full article

Polymorphic transformation is important in chemical industries, in particular, in those involving explosive molecular crystals. However, due to simulating challenges in the rare event method and collective variables, understanding the transformation mechanism of molecular crystals with a complex structure at the molecular level is poor. In this work, with the constructed order parameters (OPs) and K-means clustering algorithm, the potential of mean force (PMF) along the minimum free-energy path connecting β-HMX and δ-HMX was calculated by the finite temperature string method in the collective variables (SMCV), the free-energy profile and nucleation kinetics were obtained by Markovian milestoning with Voronoi tessellations, and the temperature effect on nucleation was also clarified. The barriers of transformation were affected by the finite-size effects. The configuration with the lower potential barrier in the PMF corresponded to the critical nucleus. The time and free-energy barrier of the polymorphic transformation were reduced as the temperature increased, which was explained by the pre-exponential factor and nucleation rate. Thus, the polymorphic transformation of HMX could be controlled by the temperatures, as is consistent with previous experimental results. Finally, the HMX polymorph dependency of the impact sensitivity was discussed. This work provides an effective way to reveal the polymorphic transformation of the molecular crystal with a cyclic molecular structure, and further to prepare the desired explosive by controlling the transformation temperature. Full article

Due to the increasing fluoride concentrations in water bodies, significant environmental concerns have arisen. This study focuses on aluminum-based materials with a high affinity for fluorine, specifically enhancing metal–organic frameworks (MOFs) with amino groups to improve their adsorption and defluorination performance. We systematically investigate the factors influencing and mechanisms governing the adsorption and defluorination behavior of amino-functionalized aluminum-based MOF materials in aqueous environments. An SEM, XRD, and FT-IR characterization confirms the successful preparation of NH₂-MIL-101 (Al). In a 10 mg/L fluoride ion solution at pH 7.0, fluoride ion removal efficiency increases with the dosage of NH₂-MIL-101 (Al), although the marginal improvement decreases beyond 0.015 g/L. Under identical conditions, the fluoride adsorption capacity of NH₂-MIL-101 (Al) is seven times greater than that of NH₂-MIL-101 (Fe). NH₂-MIL-101 (Al) demonstrates effective fluoride ion adsorption across a broad pH range, with superior fluoride uptake in acidic conditions. At a fluoride ion concentration of 7 mg/L, with 0.015 g of NH₂-MIL-101 (Al) at pH 3.0, adsorption equilibrium is achieved within 60 min, with a capacity of 31.2 mg/g. An analysis using adsorption isotherm models reveals that the fluoride ion adsorption on NH₂-MIL-101 (Al) follows a monolayer adsorption model, while kinetic studies indicate that the predominant adsorption mechanism is chemical adsorption. This research provides a scientific basis for the advanced treatment of fluoride-containing wastewater, offering significant theoretical and practical contributions. Full article

Background: Due to it containing cellulose, hemicellulose, and lignin with abundant specific functional groups which could interact with organic dyes, garlic peel (GP) might be used as an efficient biosorbent. The aim of this study is to evaluate the adsorption performances of GP-based bio-adsorbents and obtain optimum preparation conditions. Methods: GP-based bio-adsorbents were prepared by thermal pyrolysis under different temperatures (150–400 °C). The morphologies, chemical states, and surface functional groups of the adsorbents were analyzed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Batch experiments were conducted to investigate the adsorption of methylene blue (MB) under various conditions, including contact time, contact temperature, initial dye concentration, and initial pH value. The equilibrium adsorption data were fitted to different kinetic and isothermal models, and the adsorption thermodynamics were also calculated. Significant Findings: The physicochemical properties of the GP-based bio-adsorbents were primarily dominated by the pyrolysis temperature, because their morphologies and surface functional groups of GP-based bio-adsorbents significantly varied with the changes in pyrolysis temperature. The adsorption capacity of GP materials for MB decreased as the pyrolysis temperature increased. At an initial concentration of 50.00 mg L⁻¹, GP150 possessed a higher adsorption capacity of 167.74 mg g⁻¹ toward MB. The possible adsorbate–adsorbent interactions, including electrostatic attraction, hydrogen bonding, and π-π stacking, were recognized. After 10 consecutive adsorption–desorption cycles, GP150 maintained a high removal rate (88%) for MB, demonstrating its excellent adsorption performance, good reusability, and potential application in the treatment of MB-contaminated water. Full article

The production and buildup of eggshell waste represents a challenge and an opportunity. The challenge is that uncontrolled disposal of generated eggshell waste relates to a sustainability concern for the environment. The opportunity relates to utilization of this biomass resource via recycling for waste valorization, cleaner production, and development of a circular economy. This review explores the development of eggshell powder (ESP) from eggshell waste and a coverage of various ESP composite sorbents with an emphasis on their potential utility as adsorbent materials for model pollutants in solid–liquid systems. An overview of literature since 2014 outlines the development of eggshell powder (ESP) and ESP composite adsorbents for solid–liquid adsorption processes. The isolation and treatment of ESP in its pristine or modified forms by various thermal or chemical treatments, along with the preparation of ESP biocomposites is described. An overview of the physico-chemical characterization of ESP and its biocomposites include an assessment of the adsorption properties with various model pollutants (cations, anions, and organic dyes). A coverage of equilibrium and kinetic adsorption isotherm models is provided, along with relevant thermodynamic parameters that govern the adsorption process for ESP-based adsorbents. This review reveals that ESP biocomposite adsorbents represent an emerging class of sustainable materials with tailored properties via modular synthetic strategies. This review will serve to encourage the recycling and utilization of eggshell biomass waste and its valorization as potential adsorbent systems. The impact of such ESP biosorbents cover a diverse range of adsorption-based applications from environmental remediation to slow-release fertilizer carrier systems in agricultural production. Full article

This work presents a comprehensive model for lignocellulosic biomass pyrolysis, addressing kinetics, energy balances, and gas product composition with the aim of its application in wood combustion. The model consists of a two-stage global mechanism in which biomass initially reacts into tar, char, and light gases (non-condensable gases), which is followed by tar reacting into light gases and char. Experimental data from the literature are employed for determining Arrhenius kinetic parameters and key energy parameters, like tar and char heating values and the specific enthalpy of primary and secondary reactions. A methodology is introduced to derive correlations, allowing the model’s application to diverse biomass types. This work introduces several novel approaches. Firstly, a pyrolysis model that determines the composition of light gases by solving mass, species, and energy balances is developed, limiting the use of correlations from the literature only for tar and char elemental composition. The mass rate of light gases, tar, and char being produced is also determined. Secondly, kinetic parameters for primary and secondary reactions are determined following a Shafizadeh and Chin scheme but with a modified Arrhenius form dependent on $T^n$, significantly enhancing the accuracy of product composition prediction. Additionally, correlations for the enthalpies of reactions, both primary and secondary, are determined as a function of pyrolysis temperature. Primary reactions exhibit an overall endothermic behavior, while secondary reactions exhibit an overall exothermic behavior. Finally, the model is validated using cases reported in the literature, and results for light gases composition are presented. Full article

Background/Objectives: This study investigates the development of 3D chitosan-x-cobalt ferrite scaffolds (x = 5, 7.5, and 10 wt%) with interconnected porosity for potential biomedical applications. The objective was to evaluate the effects of magnetic particle incorporation on the scaffolds’ structural, mechanical, magnetic, and biological properties, specifically focusing on their biocompatibility and antimicrobial performance. Methods: Scaffolds were synthesized using freeze-drying, while cobalt ferrite nanoparticles were produced via a pilot-scale combustion reaction. The scaffolds were characterized for their physical and chemical properties, including porosity, swelling, and mechanical strength. Hydrophilicity was assessed through contact angle measurements. Antimicrobial efficacy was evaluated using time kill kinetics and agar diffusion assays, and biocompatibility was confirmed through cytotoxicity tests. Results: The incorporation of cobalt ferrite increased magnetic responsiveness, altered porosity profiles, and influenced swelling, biodegradation, and compressive strength, with a maximum value of 87 kPa at 7.5 wt% ferrite content. The scaffolds maintained non-toxicity and demonstrated bactericidal activity. The optimal concentration for achieving a balance between structural integrity and biological performance was found at 7.5 wt% cobalt ferrite. Conclusions: These findings suggest that magnetic chitosan-cobalt ferrite scaffolds possess significant potential for use in biomedical applications, including tissue regeneration and advanced healing therapies. The incorporation of magnetic properties enhances both the structural and biological functionalities, presenting promising opportunities for innovative therapeutic approaches in reconstructive procedures. Full article

The use of clays for thermal treatments and cosmetic purposes continues to be a worldwide practice, whether through the preservation of native cultural traditions, pharmaceutical formulations or integrative health and well-being practices. Special clays, such as bentonites, are very common for healing applications due to their high cation exchange capacity (CEC), high specific surface area (SSA) and alkaline pH values and, therefore, are used in multiple therapeutic and dermocosmetic treatments. Numerous bentonitic deposits occur on Porto Santo Island with different chemical weathering degrees. This research evaluates which residual soils have the most suitable characteristics for pelotherapy. The texture of residual soils varies from silt loam to loamy sand and SSA between 39 and 90 m²/g. The pH is alkaline (8.7 to 9.6), electrical conductivity ranges from 242 to 972 µS/cm, and CEC from 50.4 to 86.8 µS/cm. The residual soils have a siliciclastic composition (41.36 to 54.02% SiO₂), between 12.52 and 17.65% Al₂O₃ and between 52 and 82% smectite content, which are montmorillonite and nontronite. Specific heat capacity (0.5–0.9 J/g°C) and cooling kinetics (14.5–19 min) show that one residual soil has the potential to be suitable for pelotherapy according to the literature. Moreover, the residual soils have As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and V concentrations higher than the limits of guidelines for cosmetics and pharmaceutical products. Full article

Kidney dysfunction leads to the retention of metabolites within the blood that are not effectively cleared with conventional hemodialysis. Magnetic nanoparticle (MNP)-based absorbents have inherent properties that make them amenable to capturing toxins in the blood, notably a large surface area that can be chemically modified to enhance toxin capture and the ability to be easily collected from the blood using an external magnetic field. Cyclodextrins (CDs) present a chemical structure that facilitates the binding of small molecules. However, the hemocompatibility of MNPs modified with films composed of different native types of CDs (α, β, or γ) has not yet been investigated, which is information crucial to the potential clinical application of MNPs to supplement hemodialysis. To this end, films of α-, β-, or γ-CDs were formed on MNPs and characterized. The impact of these films on the adsorbed protein structure, composition of key adsorbed proteins, and clotting kinetics were evaluated. It was found that modified MNPs did not significantly affect the secondary structure of some proteins (albumin, lysozyme, α-lactalbumin). The adsorbed proteome from platelet-poor human plasma was evaluated as a function of film properties. Compared to non-modified nanoparticles, CD-modified MNPs exhibited a significant decrease in the adsorbed protein per surface area of MNPs. The immunoblot results showed variations in the adsorption levels of C3, fibrinogen, antithrombin, Factor XI, and plasminogen across CD-modified MNPs. The hemocompatibility experiments showed that CD-modified MNPs are compatible with human whole blood, with no significant impact on platelet activation, hemolysis, or hemostasis. Full article

The propagation rate coefficient (k_p) is one of the most crucial kinetic parameters in free-radical polymerization (FRP) as it directly governs the rate of polymerization and the resulting molecular weight distribution. The k_p in FRP can typically be obtained through experimental measurements or quantum chemical calculations, both of which can be time consuming and resource intensive. Herein, we developed a machine learning model based solely on the structural features of monomers involved in FRP, utilizing molecular embedding and a Lasso regression algorithm to predict k_p more efficiently and accurately. The result shows that the model achieves a mean absolute percentage error (MAPE) of only 5.49% in the predictions for four new monomers, which indicates that the model exhibits strong generalization capabilities and provides reliable and robust predictions. In addition, this model can accurately predict the influence of the ester side chain length of (meth)acrylates on k_p, aligning well with established scientific knowledge. This approach offers a straightforward and practical model for other researchers to rapidly obtain accurate k_p values by employing monomer structural information. The model is sufficiently general to apply to a wide range of (meth)acrylate and butadiene FRP monomers, thereby supporting kinetic modeling of polymerization reactions. Full article

Fibre deformation (or shearing of yarns) can develop during the liquid moulding of composites due to injection pressures or polymerisation (cross-linking) reactions (e.g., chemical shrinkage). On that premise, this may also induce potential residual stress–strain, warpage, and design defects in the composite part. In this paper, a developed numerical framework is customised to analyse deformations and the residual stress–strain of fibre (at a micro-scale) and yarns (at a meso-scale) during a liquid composite moulding (LCM) process cycle (fill and cure stages). This is achieved by linking flow simulations (coupled filling–curing simulation) to a transient structural model using ANSYS software. This work develops advanced User-Defined Functions (UDFs) and User-Defined Scalers (UDSs) to enhance the commercial CFD code with extra models for chemorheology, cure kinetics, heat generation, and permeability. Such models will be hooked within the conservation equations in the thermo-chemo-flow model and hence reflected by the structural model. In doing so, the knowledge of permeability, polymerisation, rheology, and mechanical response can be digitally obtained for more coherent and optimised manufacturing processes of advanced composites. Full article