Search Results (1,494)

Organic acids could act as retarders in magnesium oxysulfide (MOS) systems, not only delaying setting and improving fluidity but also enhancing compressive strength and water resistance. These effects are generally attributed to both the presence of H⁺ ions and anion chelation. However, the enhancement efficiency of different organic acids in MOS systems varies significantly due to differences in their molecular structures. To determine the underlying mechanism, this study comparatively investigated the effects of amino trimethylene phosphonic acid (ATMP) and tartaric acid (TA) on the setting time, fluidity, compressive strength, and water resistance of the MOS system, with the two additives incorporated at mole ratios to MgO ranging from 0.002 to 0.006. The mechanism behind it was revealed by discussion on the hydration heat, hydrates, and pH value. Results showed that both ATMP and TA could effectively improve the fluidity, delay the setting process, and enhance the mechanical properties, including strength and water resistance. At a mole ratio of 0.006, the incorporation of ATMP increased the 28 d compressive strength and the softening coefficient by 214.12% and 37.29%, respectively, compared with the blank group. In contrast, under the same dosage, TA led to an increase of 55.13% in the 28 d strength and 22.03% in the softening coefficient. Furthermore, hydration heat, product analysis, and pH measurements indicated that both ATMP and TA inhibited hydration during the initial hours but promoted hydration at later stages. The potential reason could be divided into two aspects: (1) H⁺ ions from ATMP and TA suppressing the formation of Mg(OH)₂; (2) anion chelation with Mg²⁺ in the liquid phase, leading to a supersaturated solution with higher saturation, which further hindered Mg(OH)₂ formation and facilitated the later development of 5Mg(OH)₂·MgSO₄·7H₂O (517 phase). By contrast, under the same mole dosage of H⁺ or anions, the enhancement in compressive strength as well as the water resistance is superior when using ATMP. This was owing to its stronger chelating ability of ATMP, which more effectively inhibited Mg(OH)₂ formation and then promoted the formation of the 517 phase. These findings confirm that the chelating ability of anions exerts an important impact on the retarding effect as well as the enhancement of strength in MOS systems. Full article

Biodegradable magnesium alloys have emerged as promising alternatives to permanent metallic implants due to their unique combination of mechanical compatibility with bone and complete resorption, addressing the persistent issues of stress shielding and secondary removal surgeries. This review critically examines the historical development of magnesium-based biomaterials, highlighting advances in alloy design, manufacturing processes, and surface engineering that now enable tailored degradation and improved clinical performance. Drawing on recent clinical and preclinical studies, we summarize improvements in corrosion resistance, mechanical properties, and biocompatibility that have supported the clinical translation of magnesium alloys across a variety of orthopedic and emerging medical applications. However, challenges remain, including unpredictable in vivo degradation kinetics, limited long-term safety data, lack of standardized testing protocols, and ongoing regulatory uncertainties. We conclude that while magnesium-based biomaterials have advanced from experimental concepts to clinically validated solutions, further progress in personalized degradation control, real-time monitoring, and harmonized regulatory frameworks is needed to fully realize their transformative clinical potential. Full article

In agricultural practice, in addition to determining the nitrogen (N_f) dose, it is necessary to effectively control its effect on currently grown crops. Meeting these conditions requires not only the use of phosphorus (P) and potassium (K), but also nutrients such as magnesium (Mg) and sulfur (S). This hypothesis was verified in a single-factor field experiment with winter wheat (WW) carried out in the 2015/2016, 2016/2017, and 2017/2018 growing seasons. The experiment consisted of seven variants: absolute control (AC), NP, NPK-MOP (K as Muriate of Potash), NPK-MOP+Ki (Kieserite), NPK-KK (K as Korn–Kali), NPK-KK+Ki, and NPK-KK+Ki+ES (Epsom Salt). The use of K as MOP increased grain yield (GY) by 6.3% compared to NP. In the NPK-KK variant, GY was 13% (+0.84 t ha⁻¹) higher compared to NP. Moreover, GYs in this fertilization variant (FV) were stable over the years (coefficient of variation, CV = 9.4%). In NPK-KK+Ki+ES, the yield increase was the highest and mounted to 17.2% compared to NP, but the variability over the years was also the highest (CV ≈ 20%). The amount of N in grain N (GN) increased progressively from 4% for NPK-MOP to 15% for NPK-KK and 25% for NPK-KK+Ki+ES in comparison to NP. The nitrogen harvest index was highly stable, achieving 72.6 ± 3.1%. All analyzed NUE indices showed a significant response to FVs. The PFP-N_f (partial factor productivity of N_f) indices increased on NPK-MOP by 5.8%, NPK-KK by 12.9%, and NPK-KK+Ki+ES by 17.9% compared to NP. The corresponding N_f recovery of N_f in wheat grain was 47.2%, 55.9%, and 64.4%, but its total recovery by wheat (grain + straw) was 67%, 74.5%, and 87.2%, respectively. In terms of the theoretical and practical value of the tested indexes, two indices, namely, NUP (nitrogen unit productivity) and NUA (nitrogen unit accumulation), proved to be the most useful. From the farmer’s production strategy, FV with K applied in the form of Korn–Kali proved to be the most stable option due to high and stable yield, regardless of weather conditions. The increase in the number of nutritional factors optimizing the action of nitrogen in winter wheat caused the phenomenon known as the “scissors effect”. This phenomenon manifested itself in a progressive increase in nitrogen unit productivity (NUP) combined with a regressive trend in unit nitrogen accumulation (NUA) in the grain versus the balance of soil available Mg (Mg_b). The studies clearly showed that obtaining grain that met the milling requirements was recorded only for NUA above 22 kg N t⁻¹ grain. This was possible only with the most intensive Mg treatment (NPK-KK+Ki and NPK-KK+Ki+ES). The study clearly showed that three of the six FVs fully met the three basic conditions for sustainable crop production: (i) stabilization and even an increase in grain yield; (ii) a decrease in the mass of inorganic N in the soil at harvest, potentially susceptible to leaching; and (iii) stabilization of the soil fertility of P, K, and Mg. Full article

Osmotic dehydration is a process involving a two-way mass transfer, during which water and substances dissolved in it are removed from the product and, at the same time, substances dissolved in a hypertonic solution penetrate into the tissues. This process has a significant effect on, among other things, the nutritional and sensory parameters, as well as the texture and shelf life of the dehydrated product. This study analyzed the effect of osmotic dehydration of beet on magnesium content following the addition of various chemical forms of magnesium (magnesium oxide, magnesium citrate, magnesium chloride) to a hypertonic solution. Magnesium was added in concentrations of 2.5 or 5.0% relative to the mass of the solution. The following compounds were used to prepare hypertonic solutions (25 and 50%): inulin, xylitol, erythritol, and sucrose. The control sample was water. A significant increase in magnesium content in the dehydrated material was confirmed. This effect was determined by many factors, among which the most important were the chemical form of magnesium, the type of osmotically active substance, magnesium concentration, and process time. The highest magnesium content was found in samples dehydrated in a 50% inulin solution with a 5.0% addition of magnesium chloride under the following conditions: 120 min/30 °C. It was also demonstrated that osmotically dehydrated samples exhibited approximately 3–5 times lower antioxidant activity in DPPH, ABTS, and ORAC tests. Full article

Microplastics (MPs) have emerged as pervasive environmental contaminants due to their widespread presence across various ecosystems, including their use in single-use plastic food ware and table salt dispensers. This issue coincides with the presence of heavy metals in water sources in Doha, Qatar. Fourier Transform Infrared (FTIR) analysis revealed that the plastic plate and spoon were composed of polyolefin, with the spoon exhibiting additional peaks that indicated oxidation or the presence of additives. Thermogravimetric Analysis (TGA) revealed that the spoon exhibited higher thermal stability, retaining approximately 10% of its mass at 700 °C, than the plate, which retained 2%, indicating the presence of complex additives or contamination. MPs in food-grade salt samples were verified through filtration and Fourier Transform Infrared (FTIR) Spectroscopy, identifying polymers such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). These MPs likely stem from exposure to packaging or environmental contaminants. FTIR spectra confirmed the integrity of the polymers after treatment. Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES) analysis revealed varying levels of heavy metals in bottled and tap water, with notable findings including detectable arsenic and lead in both, higher calcium and magnesium in bottled water, and the presence of copper present in tap water only, highlighting potential health and infrastructure-related concerns. These results highlight the possible risks associated with exposure to MPs and heavy metals from everyday products and water sources, underscoring the need for enhanced regulatory oversight and safer material choices to ensure protection. Full article

Background and Objectives: Magnesium (Mg)-based materials, such as the WE43 alloy, show potential in biomedical applications owing to their advantageous mechanical properties and biodegradability; however, their quick corrosion rate and hydrogen release restrict their general clinical utilization. This study aimed to develop a novel Mg-Zn-Ca alloy system based on WE43 alloy, evaluating the influence of Zn and Ca additions on microstructure, mechanical properties, cytocompatibility, and electrochemical behavior for potential use in biodegradable orthopedic applications. Materials and Methods: The WE43-Zn-Ca alloy system was developed by alloying standard WE43 (Mg–Y–Zr–RE) with 1.5% Zn and Ca concentrations of 0.2% (WE43_0.2Ca alloy) and 0.3% (WE43_0.3Ca alloy). Microstructural analysis was performed utilizing scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDS), while the chemical composition was validated through optical emission spectroscopy and X-ray diffraction (XRD). Mechanical properties were assessed through tribological tests. Electrochemical corrosion behavior was evaluated using potentiodynamic polarization in a 3.5% NaCl solution. Cytocompatibility was assessed in vitro on MG63 cells using cell viability assays (MTT). Results: Alloys WE43_0.2Ca and WE43_0.3Ca exhibited refined, homogeneous microstructures with grain sizes between 70 and 100 µm, without significant structural defects. Mechanical testing indicated reduced stiffness and an elastic modulus similar to human bone (19.2–20.3 GPa), lowering the risk of stress shielding. Cytocompatibility tests confirmed non-cytotoxic behavior for alloys WE43_0.2Ca and WE43_0.3Ca, with increased cell viability and unaffected cellular morphology. Conclusions: The study validates the potential of Mg-Zn-Ca alloys (especially WE43_0.3Ca) as biodegradable biomaterials for orthopedic implants due to their favorable combination of mechanical properties, corrosion resistance, and cytocompatibility. The optimization of these alloys contributed to obtaining an improved microstructure with a reduced degradation rate and a non-cytotoxic in vitro outcome, which supports efficient bone tissue regeneration and its integration into the body for complex biomedical applications. Full article

Magnesium-based biomaterials have emerged as highly promising candidates in the realm of biomedical engineering due to certain unique properties. However, their widespread application has been limited by a number of challenges, such as insufficient mechanical strength and rapid degradation rates. This study sought to advance the development of high-performance magnesium alloys by examining the microstructural evolution and associated strengthening mechanisms of Mg-Zn alloys modified with varying Nd contents. Comprehensive characterization techniques—including optical microscopy, XRD, and SEM/EDS—were employed to explain the influence of Nd additions on the microstructures. Mechanical performance was assessed through hardness testing, the RFDA method for elastic modulus, and tensile testing. The microstructural analysis of the as-cast Mg-Zn-Nd alloys revealed a complex phase composition comprising dendritic α-Mg, Mg₄₁Nd₅, and a Mg₃Nd binary phase enriched with rare earth elements. Notably, increasing the Nd content from 0.5% to 5% by weight resulted in a significant enhancement of hardness, reaching 59 HV compared to 42 HV in the base alloy. The tensile strength increased significantly from 62.9 MPa in the Mg-2.5Zn-0.5Nd alloy to 186.8 MPa in the Mg-2.5Zn-5Nd alloy. The elastic modulus values across all investigated alloys remained consistently comparable, which is expected as the elastic modulus is primarily determined by atomic bonding and is not significantly affected by alloying additions. These findings underscore the potential of Nd-alloyed Mg-Zn systems as viable, mechanically robust alternatives for next-generation biodegradable orthopedic implants. Full article

This study investigates the nutritional and chemical profile of cricket (Acheta domesticus) flour, evaluating its potential as a sustainable and highly nutritious food source. Cricket flour, with a protein content of approximately 60%, offers a significantly higher nutritional value compared to many traditional food sources. It is particularly rich in essential amino acids, making it a valuable and sustainable protein alternative. Additionally, the flour is rich in minerals such as potassium, calcium, magnesium, copper, and zinc. The administration of 100 g of cricket flour would exceed the recommended daily intake for adults for most nutrients, making its incorporation into more traditional foods such as bread and pasta at low percentages feasible, easily compensating for any imbalances and increasing their nutritional values. We found that an addition of a mere 10% of cricket flour to produce an experimental pasta fulfilled half of the recommended daily intake values for protein, lipids, and minerals. Chemical analyses of the pure cricket flour revealed only trace amounts of polycyclic aromatic hydrocarbons (PAHs) and linear alkanes, with concentrations well below safety thresholds established for other food categories, indicating that cricket flour is safe for human consumption. The study’s findings confirm that cricket flour is a promising sustainable protein source, and its integration into classic foods could safely contribute to alleviating iron and copper deficiencies as well as malnutrition. Full article

Biodegradable metallic implants represent a paradigm shift in implantology, eliminating secondary removal surgeries through predictable controlled degradation. This review systematizes current achievements in selective laser melting (SLM) of biodegradable metals (Mg, Fe, Zn), analyzing how processing parameters influence microstructure, mechanical properties, and degradation kinetics. Key findings demonstrate that SLM-produced Mg alloys achieve bone-matching modulus (40–45 GPa) with moderate degradation (1–3 mm/year); Fe-based systems provide superior strength (400–600 MPa) but slower degradation (0.1–0.5 mm/year); while Zn alloys offer intermediate properties. Design strategies for porous/lattice structures enhancing osseointegration and enabling property gradients are discussed. Major challenges include controlling degradation kinetics, optimizing SLM parameters for reactive metals, standardizing testing methodologies, and regulatory harmonization. This comprehensive analysis provides systematic guidelines for material selection and process optimization, establishing a foundation for developing next-generation personalized biodegradable implants. Full article

In this paper, dedicated material models were developed and verified for three melts of EN AW-7021 alloy, differing in zinc and magnesium content, for tube extrusion conditions. Based on the plastometric tests, it was found that in the studied range of strain parameters, the analyzed melts of the same aluminum alloy showed different sensitivity to strain rate and temperature. In addition, a significant effect of magnesium and zinc content on the plasticity of the tested material was observed. Therefore, dedicated material models describing stress changes were developed for each melt analyzed. The models were then implemented into the material database of the QForm-Extrusion^® program, which was used for the theoretical analysis of the industrial extrusion process. In order to verify the results of numerical calculations, industrial tests of the extrusion process were carried out. The force parameters and the rate of the extrusion process were mainly analyzed. The use of dedicated material models for each melt contributed to the accuracy of numerical modeling. A high degree of compliance was obtained regarding the theoretical and experimental extrusion force and the velocity of metal flowing out of the die cavity, among others. Full article

Natural phosphate ores frequently contain calcium–magnesium carbonate minerals as gangue components. Their separation from target phosphate minerals poses significant challenges due to analogous surface characteristics. The flotation differentiation between fluorapatite and dolomite remains a key research focus in mineral processing. In conventional collector systems, selective depressants critically govern separation efficiency, as their interfacial specificity directly determines beneficiation outcomes. The selective depression behavior of fulvic acid (FA) in modulating fluorapatite–dolomite separation efficiency within oleate-dominated flotation systems was elucidated through micro-flotation experiments, complemented by zeta potential measurements, contact angle analysis, Fourier-transform infrared spectroscopy (FTIR), and molecular dynamics (MD) simulations. The findings revealed that fluorapatite and dolomite both exhibit high floatability under NaOl-mediated collector systems in the absence of depressant additives, leading to negligible selectivity in the differential separation of the mineral pair. However, the float of fluorapatite particles in weakly acidic conditions was strongly depressed when a small amount of FA was added as a depressant, while exerting minimal impact on dolomite’s floatability. In binary artificial mixed-mineral flotation systems, under optimized flotation conditions (pH 5.0, 60 mg/L NaOl, and 15 mg/L FA), the concentrate achieved a P₂O₅ grade of 33.86% with a fluorapatite recovery rate of 92.36%, demonstrating significant selective separation of fluorapatite from dolomite. Subsequent analysis revealed that FA competitively chemisorbs with NaOl on fluorapatite surfaces, selectively reducing the hydrophobicity of the fluorapatite surface and suppressing fluorapatite floatability, thereby enabling effective differential liberation of the mineral pair. Full article

In bulk liquid or on solid surfaces, nanobubbles (NBs) are gaseous domains at the nanoscale. They stand out due to their extended (meta)stability and great potential for use in practical settings. However, due to the high energy cost of bubble generation, maintenance issues, membrane bio-fouling, and the small actual population of NBs, significant advancements in nanobubble engineering through traditional mechanical generation approaches have been impeded thus far. With the introduction of the electric field approach to NB creation, which is based on electrostrictive NB generation from an incoming population of “electro-fragmented” meso-to micro bubbles (i.e., with bubble size broken down by the applied electric field), when properly engineered with a convective-flow turbulence profile, there have been noticeable improvements in solid-state operation and energy efficiency, even allowing for solar-powered deployment. Here, these innovative methods were applied to a selection of upstream and downstream activities in the oil–water–fuels nexus: advancing core flood tests, oil–water separation, boosting the performance of produced-water treatment, and improving the thermodynamic cycle efficiency and carbon footprint of internal combustion engines. It was found that the application of electric field NBs results in a superior performance in these disparate operations from a variety of perspectives; for instance, ~20 and 7% drops in surface tension for CO₂- and air-NBs, respectively, a ~45% increase in core-flood yield for CO₂-NBs and 55% for oil–water separation efficiency for air-NBs, a rough doubling of magnesium- and calcium-carbonate formation in produced-water treatment via CO₂-NB addition, and air-NBs boosting diesel combustion efficiency by ~16%. This augurs well for NBs being a potent agent for sustainability in the oil and fuels sector (whether up-, mid-, or downstream), not least in terms of energy efficiency and environmental sustainability. Full article

Magnesium alloys are lightweight metals but suffer from high corrosion susceptibility due to their chemical reactivity, limiting their large-scale applications. To enhance corrosion resistance, this work combines Li–Al layered double hydroxides (LDHs) with triethylenetetramine (TETA) inhibitors to form an efficient corrosion protection system. Electrochemical tests, SEM, FT-IR, XPS, and 3D depth-of-field microscopy were employed to evaluate TETA-modified Li–Al LDH coatings at varying concentrations. Among them, the Li–Al LDHs without the addition of a TETA corrosion inhibitor decreased significantly at |Z|_{0.01 Hz} after immersion for 4 h. However, the Li–Al LDHs coating of 23.5 mM TETA experienced a sudden drop at |Z|_{0.01 Hz} after holding for about 60 h, and the Li–Al LDHs coating of 70.5 mM TETA also experienced a sudden drop at |Z|_{0.01 Hz} after holding for about 132 h. By contrast, at the optimal concentration (47 mM), after 24 h of immersion, the maximum |Z|_{0.01 Hz} reached 7.56 × 10⁵ Ω∙cm²—three orders of magnitude higher than pure Li–Al LDH coated AZ31 (2.55 × 10² Ω∙cm²). After 300 h of immersion, the low-frequency impedance remained above 10⁵ Ω∙cm², demonstrating superior long-term protection. TETA modification significantly improved the durability of Li–Al LDHs coatings, addressing the short-term protection limitation of standalone Li–Al LDHs. Li–Al LDHs themselves have a layered structure and effectively capture corrosive Cl⁻ ions in the environment through ion exchange capacity, reducing the corrosion of the interface. Furthermore, TETA exhibits strong adsorption on Li–Al LDHs layers, particularly at coating defects, enabling rapid barrier formation. This inorganic–organic hybrid design achieves defect compensation and enhanced protective barriers. Full article

Aiming at the problem of synergistic regulation of setting time and strength of brucite-based magnesium phosphate cement (BMPC), this study used ammonium chloride (AC) as a variable, and revealed the regulation mechanism of AC on the hydration behavior of BMPC through the tests of setting time, fluidity, and compressive strength, as well as the monitoring of pH-ion concentration, and the microanalysis of XRD-TG-MIP. The results showed that the optimal performance combination of BMPC (setting time of 16 min, fluidity of 120 mm, and compressive strength of 20.5/30.7/54.5 MPa at 3 h/1 d/28 d, respectively) was obtained when AC was doped at a dosage of 4%. The mechanism of retardation stems from the fact that the addition of AC inhibits the dissolution rate of ADP and retards the hydration reaction of Mg²⁺ and $\mathrm{P}{\mathrm{O}}_4^{3-}$. An appropriate amount of AC can optimize the pore structure of the BMPC matrix and improve the compressive strength of the matrix. The BMPC system based on complete replacement of magnesite by brucite not only significantly reduces carbon emission and cost, but also provides a new path for the development of low-carbon MPC. Full article

This study explores the flame retardancy and structural behavior of silicone foam composites filled with halogen-free flame retardants, aiming to evaluate their feasibility for use in mass transportation applications. Silicone foam specimens incorporating magnesium hydroxide and expandable graphite were prepared and compared with unfilled silicone foam under both static and dynamic loading conditions. Uniaxial compression and simple shear tests were conducted to assess mechanical behavior, and a second-order Ogden model was employed to represent hyperelasticity in the finite element analysis. Fire performance was evaluated using cone calorimeter tests in accordance with ISO 5660-1. The results showed a 53.6% reduction in peak heat release rate (PHRR) and a 48.1% decrease in MARHE upon the addition of flame retardants, satisfying relevant fire safety standards. Although the addition of fillers increased the compressive stiffness and reduced rebound resilience, static comfort indices remained within acceptable ranges. These findings confirm that halogen-free filled silicone foams exhibit significantly enhanced fire retardancy while maintaining sufficient mechanical integrity and seating comfort, demonstrating their potential as eco-friendly alternatives to conventional polyurethane foams in large-scale transportation applications. Full article