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Nutrients May 2024Endothelial dysfunction is a crucial event in the early pathogenesis of cardiovascular diseases and is linked to magnesium (Mg) deficiency. Indeed, in endothelial cells,...
Endothelial dysfunction is a crucial event in the early pathogenesis of cardiovascular diseases and is linked to magnesium (Mg) deficiency. Indeed, in endothelial cells, low Mg levels promote the acquisition of a pro-inflammatory and pro-atherogenic phenotype. This paper investigates the mechanisms by which Mg deficiency promotes oxidative stress and affects endothelial behavior in human umbilical vascular endothelial cells (HUVECs). Our data show that low Mg levels trigger oxidative stress initially by increasing NAPDH oxidase activity and then by upregulating the pro-oxidant thioredoxin-interacting protein TXNIP. The overproduction of reactive oxygen species (ROS) activates NF-κB, leading to its increased binding to the inducible nitric oxide synthase (iNOS) promoter, with the consequent increase in iNOS expression. The increased levels of nitric oxide (NO) generated by upregulated iNOS contribute to disrupting endothelial cell function by inhibiting growth and increasing permeability. In conclusion, we provide evidence that multiple mechanisms contribute to generate a pro-oxidant state under low-Mg conditions, ultimately affecting endothelial physiology. These data add support to the notion that adequate Mg levels play a significant role in preserving cardiovascular health and may suggest new approaches to prevent or manage cardiovascular diseases.
Topics: Humans; Nitric Oxide Synthase Type II; Human Umbilical Vein Endothelial Cells; Magnesium Deficiency; Oxidative Stress; Reactive Oxygen Species; Nitric Oxide; Magnesium; NF-kappa B; Carrier Proteins; Endothelium, Vascular
PubMed: 38794644
DOI: 10.3390/nu16101406 -
Materials (Basel, Switzerland) May 2024Red mud (RM) is an industrial waste generated in the process of aluminum refinement. The recycling and reusing of RM have become urgent problems to be solved. To explore...
Red mud (RM) is an industrial waste generated in the process of aluminum refinement. The recycling and reusing of RM have become urgent problems to be solved. To explore the feasibility of using RM in geotechnical engineering, this study combined magnesium oxide (MgO) (or calcium oxide (CaO)) with RM as an RM-based binder, which was then used to stabilize the soil. The physical, mechanical, and micro-structural properties of the stabilized soil were investigated. As the content of MgO or CaO in the mixture increased, the unconfined compressive strength (UCS) of the RM-based cementitious materials first increased and then decreased. For the soils stabilized with RM-MgO or RM-CaO, the UCS increased and then decreased, reaching a maximum at RM:MgO = 5:5 or RM:CaO = 8:2. The addition of sodium hydroxide (NaOH) promoted the hydration reaction. The UCS enhancement ranged from 8.09% to 66.67% for the RM-MgO stabilized soils and 204.6% to 346.6% for the RM-CaO stabilized soils. The optimum ratio of the RM-MgO stabilized soil (with NaOH) was 2:8, while that of the RM-CaO stabilized soil (with NaOH) was 4:6. Freeze-thaw cycles reduced the UCS of the stabilized soil, but the resistance of the stabilized soil to freeze-thaw erosion was significantly improved by the addition of RM-MgO or RM-CaO, and the soil stabilized with RM-MgO had better freeze-thaw resistance than that with RM-CaO. The hydrated magnesium silicate generated by the RM-MgO stabilized soil and the hydrated calcium silicate generated by the RM-CaO stabilized soil helped to improve the UCS of the stabilized soil. The freeze-thaw cycles did not weaken the formation of hydration products in the stabilized soil but could result in physical damage to the stabilized soils. The decrease in the UCS of the stabilized soil was mainly due to physical damage.
PubMed: 38793407
DOI: 10.3390/ma17102340 -
Micromachines May 2024A high-temperature-resistance single-crystal magnesium oxide (MgO) extrinsic Fabry-Perot (FP) interferometer (EFPI) fiber-optic vibration sensor is proposed and...
A high-temperature-resistance single-crystal magnesium oxide (MgO) extrinsic Fabry-Perot (FP) interferometer (EFPI) fiber-optic vibration sensor is proposed and experimentally demonstrated at 1000 °C. Due to the excellent thermal properties (melting point > 2800 °C) and optical properties (transmittance ≥ 90%), MgO is chosen as the ideal material to be placed in the high-temperature testing area. The combination of wet chemical etching and direct bonding is used to construct an all-MgO sensor head, which is favorable to reduce the temperature gradient inside the sensor structure and avoid sensor failure. A temperature decoupling method is proposed to eliminate the cross-sensitivity between temperature and vibration, improving the accuracy of vibration detection. The experimental results show that the sensor is stable at 20-1000 °C and 2-20 g, with a sensitivity of 0.0073 rad (20 °C). The maximum nonlinearity error of the vibration sensor measurement after temperature decoupling is 1.17%. The sensor with a high temperature resistance and outstanding dynamic performance has the potential for applications in testing aero-engines and gas turbine engines.
PubMed: 38793190
DOI: 10.3390/mi15050616 -
Bioengineering (Basel, Switzerland) May 2024Magnesium (Mg) is considered an attractive option for orthopedic applications due to its density and elastic modulus close to the natural bone of the body, as well as... (Review)
Review
Magnesium (Mg) is considered an attractive option for orthopedic applications due to its density and elastic modulus close to the natural bone of the body, as well as biodegradability and good tensile strength. However, it faces serious challenges, including a high degradation rate and, as a result, a loss of mechanical properties during long periods of exposure to the biological environment. Also, among its other weaknesses, it can be mentioned that it does not deal with bacterial biofilms. It has been found that making composites by synergizing its various components can be an efficient way to improve its properties. Among metal oxide nanoparticles, magnesium oxide nanoparticles (MgO NPs) have distinct physicochemical and biological properties, including biocompatibility, biodegradability, high bioactivity, significant antibacterial properties, and good mechanical properties, which make it a good choice as a reinforcement in composites. However, the lack of comprehensive understanding of the effectiveness of Mg NPs as Mg matrix reinforcements in mechanical, corrosion, and biological fields is considered a challenge in their application. While introducing the role of MgO NPs in medical fields, this article summarizes the most important results of recent research on the mechanical, corrosion, and biological performance of Mg/MgO composites.
PubMed: 38790374
DOI: 10.3390/bioengineering11050508 -
Scientific Reports May 2024Direct growth of oxide film on silicon is usually prevented by extensive diffusion or chemical reaction between silicon (Si) and oxide materials. Thermodynamic stability...
Direct growth of oxide film on silicon is usually prevented by extensive diffusion or chemical reaction between silicon (Si) and oxide materials. Thermodynamic stability of binary oxides is comprehensively investigated on Si substrates and shows possibility of chemical reaction of oxide materials on Si surface. However, the thermodynamic stability does not include any crystallographic factors, which is required for epitaxial growth. Adsorption energy evaluated by total energy estimated with the density functional theory predicted the orientation of epitaxial film growth on Si surface. For lower computing cost, the adsorption energy was estimated without any structural optimization (simple total of energy method). Although the adsorption energies were different on simple ToE method, the crystal orientation of epitaxial growth showed the same direction with/without the structural optimization. The results were agreed with previous simulations including structural optimization. Magnesium oxide (MgO), as example of epitaxial film, was experimentally deposited on Si substrates and compared with the results from the adsorption evaluation. X-ray diffraction showed cubic on cubic growth [MgO(100)//Si(100) and MgO(001)//Si(001)] which agreed with the results of the adsorption energy.
PubMed: 38740769
DOI: 10.1038/s41598-024-61564-8 -
Materials (Basel, Switzerland) May 2024A serious risk that harms the safe use of water and affects aquatic ecosystems is water pollution. This occurs when the water's natural equilibrium is disrupted by an...
A serious risk that harms the safe use of water and affects aquatic ecosystems is water pollution. This occurs when the water's natural equilibrium is disrupted by an excessive amount of substances, both naturally occurring and as a byproduct of human activities, that have varied degrees of toxicity. Radiation from Cs isotopes, which are common components of radioactive waste and are known for their long half-lives (30 years), which are longer than the natural decay processes, is a major source of contamination. Adsorption is a commonly used technique for reducing this kind of contamination, and zeolite chabazite has been chosen as the best adsorbent for cesium in this particular situation. The purpose of this research is to investigate a composite material based on magnesium phosphate cement (MPC). Magnesium oxide (MgO), potassium dihydrogen phosphate (KHPO), and properly selected retarders are used to create the MPC. The optimal conditions for this composite material are investigated through the utilization of X-ray diffraction, scanning electron microscopy, BET surface area analysis, and atomic absorption spectroscopy. The principal aim is to enable innovations in the elimination of radioactive waste-contaminated water using effective cesium removal. The most promising results were obtained by using KHPO as an acid, and MgO as a base, and aiming for an M/P ratio of two or four. Furthermore, we chose zeolite chabazite as a crucial component. The best adsorption abilities for Cs were found at Q = 106.997 mg/g for S and Q = 122.108 mg/g for S. As a result, zeolite is an eco-friendly material that is a potential usage option, with many benefits, such as low prices, stability, and ease of regeneration and use.
PubMed: 38730938
DOI: 10.3390/ma17092132 -
Materials (Basel, Switzerland) Apr 2024Utilizing MgO as the precursor and deionized water as the solvent, this study synthesized nanoparticles of Mg(OH) via hydrothermal methods, aiming to control its purity,...
Utilizing MgO as the precursor and deionized water as the solvent, this study synthesized nanoparticles of Mg(OH) via hydrothermal methods, aiming to control its purity, particle size, and morphology by understanding its growth under non-uniform nucleation. Characterization of crystal morphology and structure was conducted through scanning electron microscopy and X-ray diffraction, while laser particle size detection assessed the secondary particle size distribution. The study focused on how MgO's hydrothermal process conditions influence Mg(OH) crystal growth, particularly through ion concentration and release rate adjustments to direct crystal growth facets. These adjustments shifted the dominant growth plane, enhancing the peak intensity ratio I001/I101 from 1.03 to 2.14, thereby reducing surface polarity and secondary aggregation of crystals. The study of the physicochemical properties of the same sample at different times revealed the pattern of crystal dissolution and recrystallization. A 2 h hydrothermal reaction notably altered the particle size distribution, with a decrease in particles sized 0.2~0.4 μm and an increase in those sized 0.4~0.6 μm, alongside new particles over 1 μm, indicating a shift toward uniformity through dissolution and recrystallization. Optimal conditions (6% magnesium oxide concentration, 160 °C, 2 h) led to the synthesis of highly dispersed, uniformly sized magnesium hydroxide, showcasing a simple, eco-friendly, and high-yield process.
PubMed: 38730761
DOI: 10.3390/ma17091956 -
Heliyon May 2024This research attempted to prepare silver-doped zinc oxide/magnesium oxide nanocomposite (Ag-doped ZnO/MgO-NCP) using plant extract. The synthesized NCP was...
This research attempted to prepare silver-doped zinc oxide/magnesium oxide nanocomposite (Ag-doped ZnO/MgO-NCP) using plant extract. The synthesized NCP was investigated by X-ray diffraction analysis (XRD), Fourier Transform Infrared (FT-IR), Field Emission Scanning Electron Microscope (FESEM), Energy dispersive X-ray spectroscopy (EDX), Mapping, and UV-Visible analyses. The XRD data displayed cubic crystal structures for silver & magnesium oxide and a hexagonal framework for zinc oxide. Also, FESEM and PSA images of NCP pointed out, that the average size of the spherical morphology is about 10-16 nm, while the analysis of EDX confirmed the attendance of Zn, Mg, Ag, and O elements. Under UVA light, we tested the photocatalytic activity of NCP to the degradation of Methylene blue (MB) and Rhodamine B (RhB) dyes in various temperatures (400, 500, and 600 °C). The results of the photocatalytic test displayed that the degradation percentage of MB dye in pH = 9, nanocomposite amount ∼30 mg, and dye concentration ∼1 × 10 M was about 98 %. We also evaluated the cytotoxicity of nanocomposite on cancer CT-26 cell line through the MTT method and obtained an IC value of 250 μg/mL.
PubMed: 38726184
DOI: 10.1016/j.heliyon.2024.e30374 -
RSC Advances May 2024Monolithic adsorbent removal of fluoride from water is considered an effective and non-secondary pollution method. Here, a portable hydroxyl-functionalized coal...
Monolithic adsorbent removal of fluoride from water is considered an effective and non-secondary pollution method. Here, a portable hydroxyl-functionalized coal gangue-based cordierite porous ceramic sheet (ACGC-Fe) is prepared by using coal gangue solid waste with a specific silicon-aluminum-rich composition ratio and a small amount of magnesium oxide as a raw material through powder compression molding and mild chemical modification. The prepared ACGC-Fe can be used to treat fluorine-containing wastewater and the maximum adsorption of fluorine can reach 18.69 mg g. The Langmuir (Freundlich) adsorption isotherm model and pseudo-second-order kinetic model here provided a satisfactory description of the fluoride removal operating mechanism, and it is confirmed that the adsorption mechanism of ACGC-Fe is mainly attributed to the chemisorption of hydrogen bonds (with hydroxyl group) and ionic bonds (with metal), and physical adsorption based on cordierite porous ceramic pores. This research will provide a new idea for designing high-performance materials by mining and analyzing the composition and structure characteristics of coal gangue solid waste itself and broaden the application range of high-value-added coal gangue solid waste.
PubMed: 38725563
DOI: 10.1039/d4ra01928h -
Bioactive Materials Jul 2024Magnesium phosphate bone cements (MPC) have been recognized as a viable alternative for bone defect repair due to their high mechanical strength and biodegradability....
Magnesium phosphate bone cements (MPC) have been recognized as a viable alternative for bone defect repair due to their high mechanical strength and biodegradability. However, their poor porosity and permeability limit osteogenic cell ingrowth and vascularization, which is critical for bone regeneration. In the current study, we constructed a novel hierarchically-porous magnesium phosphate bone cement by incorporating extracellular matrix (ECM)-mimicking electrospun silk fibroin (SF) nanofibers. The SF-embedded MPC (SM) exhibited a heterogeneous and hierarchical structure, which effectively facilitated the rapid infiltration of oxygen and nutrients as well as cell ingrowth. Besides, the SF fibers improved the mechanical properties of MPC and neutralized the highly alkaline environment caused by excess magnesium oxide. Bone marrow stem cells (BMSCs) adhered excellently on SM, as illustrated by formation of more pseudopodia. CCK8 assay showed that SM promoted early proliferation of BMSCs. Our study also verified that SM increased the expression of OPN, RUNX2 and BMP2, suggesting enhanced osteogenic differentiation of BMSCs. We screened for osteogenesis-related pathways, including FAK signaing, Wnt signaling and Notch signaling, and found that SM aided in the process of bone regeneration by suppressing the Notch signaling pathway, proved by the downregulation of NICD1, Hes1 and Hey2. In addition, using a bone defect model of rat calvaria, the study revealed that SM exhibited enhanced osteogenesis, bone ingrowth and vascularization compared with MPC alone. No adverse effect was found after implantation of SM . Overall, our novel SM exhibited promising prospects for the treatment of critical-sized bone defects.
PubMed: 38698920
DOI: 10.1016/j.bioactmat.2024.03.021