A Simple and Efficient Magnesium Hydroxide Modification Strategy for Flame-Retardancy Epoxy Resin.

Magnesium hydroxide, as a green inorganic flame-retardancy additive, has been widely used in polymer flame retardancy. However, magnesium hydroxide is difficult to disperse with epoxy resin (EP), and its flame-retardancy performance is poor, so it is difficult to use in flame-retardant epoxy resin. In this study, an efficient magnesium hydroxide-based flame retardant (MH@PPAC) was prepared by surface modification of 2-(diphenyl phosphine) benzoic acid (PPAC) using a simple method. The effect of MH@PPAC on the flame-retardancy properties for epoxy resins was investigated, and the flame-retardancy mechanism was studied. The results show that 5 wt% MH@PPAC can increase the limiting oxygen index for EP from 24.1% to 38.9%, achieving a V-0 rating. At the same time, compared to EP, the peak heat release rate, peak smoke production rate, total smoke production rate, and peak CO generation rate for EP/5 wt% MH@PPAC composite material decreased by 53%, 45%, 51.85%, and 53.13% respectively. The cooperative effect for PPAC and MH promotes the formation of a continuous and dense char layer during the combustion process for the EP-blend material, significantly reducing the exchange for heat and combustible gases, and effectively hindering the combustion process. Additionally, the surface modification of PPAC enhances the dispersion of MH in the EP matrix, endowing EP with superior mechanical properties that meet practical application requirements, thereby expanding the application scope for flame-retardant EP-blend materials.

Investigation of Crystallization Growth Characteristics of Mg(OH)2 Crystals under Unconstrained Conditions.

Utilizing MgO as the precursor and deionized water as the solvent, this study synthesized nanoparticles of Mg(OH)2 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)2 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.

Flaxseed powder and magnesium hydroxide syrup on the intestinal function of patients with acute myocardial infarction in intensive care units.

Background: Flaxseed powder seems to improve bowel movements in these patients. Therefore, this study compares the effects of flaxseed powder and magnesium hydroxide on bowel movements of acute myocardial infarction patients hospitalized in ICU. Methods: The population of the present parallel randomized controlled clinical trial included 70 acute myocardial infarction patients hospitalized in ICU who had no history of chronic constipation. The patients in the intervention group were given three sachets of flaxseed powder (each sachet was 3 g) twice a day for four days. The patients in the control group were given 20 cc of magnesium hydroxide syrup each morning. The Bristol scale was used to describe stool consistency. Results: The mean and standard deviation of the number of bowel movements within five days after intervention are 1.86 ± 1.08 and 1.6 ± 0.65 in the intervention and the control groups, respectively. The frequency of normal stool consistency of the first bowel movement is 94.3% for the intervention group and 85.7% for the control group, which shows no significant differences between the two groups in terms of stool consistency and bowel movement frequency (P=0.510). The bowel movements started on average after 35.2±97.97 hours in the flaxseed group and 24.771±2.677 hours in the magnesium hydroxide group (P=0.023). Conclusion: The results showed that flaxseed powder increases bowel movement frequency and improves the patients' stool consistency, but the differences between the two groups are insignificant. Finally, the time to the first defecation was shorter in the magnesium hydroxide group.

Investigation on the Initial Stage of the Dehydration Process in Mg(OH)2 by Density Functional Theory Calculations.

Mg(OH)2/MgO has been attracting considerable interest as a viable candidate for thermochemical heat storage materials, particularly within the temperature range of 200-400 °C. Nonetheless, the typical dehydration temperature of Mg(OH)2, which occurs within the 300-400 °C range, needs to be reduced to enhance its effectiveness in various applications for thermal energy storage. While several studies have shown that heterospecies doping can lower the dehydration temperature, the fundamental mechanism underlying this effect still remains unclear. Here, we employed density functional theory calculations to elucidate the dehydration mechanism of Mg(OH)2, with a particular focus on the initial stage of the dehydration that determines the temperature beginning the reaction. Our findings indicate that the formation of water molecules on the (001) surface is critical in the early stages of the dehydration. This discovery provides a comprehensive explanation for the role of dopants (Na, Li, or LiCl) in reducing the dehydration temperature by decreasing the formation energy of paired H and OH defects and the migration barrier of H on the surface. The present study will significantly advance the development of novel dopants for Mg(OH)2, facilitating a lower dehydration temperature and, thereby, increasing its suitability for heat storage applications.

Property Enhancement of Waste Printed Circuit Boards Powders Reinforced Polypropylene by In Situ Magnesium Hydroxide Impregnation from Waste Lye.

Using alkali pretreatment can effectively remove residual variable-valence metals from non-metallic powder (WPCBP) in waste printed circuit boards. However, substantial amounts of waste lye are generated, which causes secondary pollution. On this basis, this study innovatively utilized waste alkali lye to prepare nano-magnesium hydroxide. When the dispersant polyethylene glycol 6000 was used at a dosage of 3 wt.% of the theoretical yield of magnesium hydroxide, the synthesized nano-magnesium hydroxide exhibited well-defined crystallinity, good thermal stability and uniform particle size distribution, with a median diameter of 197 nm. Furthermore, the in situ method was selected to prepare WPCBP/Mg(OH)2 hybrid filler (MW) and the combustion behavior, thermal and mechanical properties of PP blends filled with MW were evaluated. The combustion behavior of the PP/MW blends increased with the increasing hybrid ratio of Mg(OH)2, and the MW hybrid filler reinforced PP blends showed better thermal and mechanical properties compared to the PP/WPCBP blends. Furthermore, the dynamic mechanical properties of the PP/MW blends were also increased due to the improved interfacial adhesion between the MW fillers and PP matrix. This method demonstrated high economic and environmental value, providing a new direction for the high value-added utilization of WPCBP.

Modulating Thermal Conductivity and Flame Retardancy of Polyolefin Composites via Distributed Structures of Magnesium Hydroxide and Hexagonal Boron Nitride.

Thermally conductive and flame-retardant polyolefin composites are facing great challenges in meeting the increasing demands for fire safety and thermal management. Aiming at simultaneously enhancing thermal conductivity and flame retardancy, hexagonal boron nitride (hBN) and magnesium hydroxide (MH) were adopted in ethylene-vinyl acetate copolymer/polyolefin elastomer (EVA/POE) blends to design composites with selective filler distributions and co-continuous networks via different processing schemes. The thermal conductivity and flame retardancy show strong dependence on the distributed structure of hBN and MH. The composites with hBN-rich centers and MH-rich edges in the filled POE phase show a thermal conductivity of 0.70 W/(m·K) and an LOI of 27.7%, which are very close to the thermal conductivity of EVA/POE/hBN and the LOI of EVA/POE/MH at the same total filler content. The composites with MH-rich centers and hBN-rich edges show pHRR, THR and TSP values of 169 kW/m2, 49.8 MJ/m2 and 1.8 m2, which are decreased by 40%, 33% and 62% in comparison with EVA/POE/MH, respectively. Modulating the filler structure distribution provides a strategy to co-enhance thermal conductivity and flame retardancy.

Magnesium Hydroxide as a Versatile Nanofiller for 3D-Printed PLA Bone Scaffolds.

Polylactic acid (PLA) has attracted much attention in bone tissue engineering due to its good biocompatibility and processability, but it still faces problems such as a slow degradation rate, acidic degradation product, weak biomineralization ability, and poor cell response, which limits its wider application in developing bone scaffolds. In this study, Mg(OH)2 nanoparticles were employed as a versatile nanofiller for developing PLA/Mg(OH)2 composite bone scaffolds using fused deposition modeling (FDM) 3D printing technology, and its mechanical, degradation, and biological properties were evaluated. The mechanical tests revealed that a 5 wt% addition of Mg(OH)2 improved the tensile and compressive strengths of the PLA scaffold by 20.50% and 63.97%, respectively. The soaking experiment in phosphate buffered solution (PBS) revealed that the alkaline degradation products of Mg(OH)2 neutralized the acidic degradation products of PLA, thus accelerating the degradation of PLA. The weight loss rate of the PLA/20Mg(OH)2 scaffold (15.40%) was significantly higher than that of PLA (0.15%) on day 28. Meanwhile, the composite scaffolds showed long-term Mg2+ release for more than 28 days. The simulated body fluid (SBF) immersion experiment indicated that Mg(OH)2 promoted the deposition of apatite and improved the biomineralization of PLA scaffolds. The cell culture of bone marrow mesenchymal stem cells (BMSCs) indicated that adding 5 wt% Mg(OH)2 effectively improved cell responses, including adhesion, proliferation, and osteogenic differentiation, due to the release of Mg2+. This study suggests that Mg(OH)2 can simultaneously address various issues related to polymer scaffolds, including degradation, mechanical properties, and cell interaction, having promising applications in tissue engineering.

Three Birds, One Stone: An Osteo-Microenvironment Stage-Regulative Scaffold for Bone Defect Repair through Modulating Early Osteo-Immunomodulation, Middle Neovascularization, and Later Osteogenesis.

In order to repair critical-sized bone defects, various polylactic acid-glycolic acid (PLGA)-based hybrid scaffolds are successfully developed as bone substitutes. However, the byproducts of these PLGA-based scaffolds are known to acidify the implanted site, inducing tiresome acidic inflammation. Moreover, these degradation productions cannot offer an osteo-friendly microenvironment at the implanted site, matching natural bone healing. Herein, inspired by bone microenvironment atlas of natural bone-healing process, an osteo-microenvironment stage-regulative scaffold (P80/D10/M10) is fabricated by incorporating self-developed decellularized bone matrix microparticles (DBM-MPs) and multifunctional magnesium hydroxide nanoparticles (MH-NPs) into PLGA with an optimized proportion using low-temperature rapid prototyping (LT-RP) 3D-printing technology. The cell experiments show that this P80/D10/M10 exhibits excellent properties in mechanics, biocompatibility, and biodegradability, meanwhile superior stimulations in osteo-immunomodulation, angiogenesis, and osteogenesis. Additionally, the animal experiments determined that this P80/D10/M10 can offer an osteo-friendly microenvironment in a stage-matched pattern for enhanced bone regeneration, namely, optimization of early inflammation, middle neovascularization, and later bone formation. Furthermore, transcriptomic analysis suggested that the in vivo performance of P80/D10/M10 on bone defect repair is mostly attributed to regulating artery development, bone development, and bone remodeling. Overall, this study reveals that the osteo-microenvironment stage-regulative scaffold provides a promising treatment for bone defect repair.

Fatal Hypermagnesemia in Patients Taking Magnesium Hydroxide.

Hypermagnesemia is a rare but potentially fatal electrolyte disorder often overlooked because of its unfamiliarity. Magnesium is regulated through a balance of bone, intestinal absorption, and renal excretion. Hypermagnesemia typically arises from excessive magnesium intake or reduced renal excretion; however, it also occurs in patients with normal kidney function. Herein, we report two cases of hypermagnesemia in patients taking magnesium hydroxide for constipation. The first case involved an 82-year-old woman with end-stage renal disease who developed metabolic encephalopathy due to hypermagnesemia, after taking 3,000 mg of magnesium hydroxide daily for constipation. Her magnesium level was 9.9 mg/dL. Her treatment involved discontinuing magnesium hydroxide and continuing hemodialysis, which led to her recovery. In the second case, a 50-year-old woman with a history of cerebral hemorrhage and mental retardation developed hypermagnesemia despite having normal renal function. She was also taking magnesium hydroxide for constipation, and her magnesium level was 11.0 mg/dL. She experienced cardiac arrest while preparing for continuous renal replacement therapy (CRRT). After achieving return of spontaneous circulation, CRRT was initiated, and her magnesium level showed a decreasing trend. However, vital signs and lactate levels did not recover, leading to death. These cases highlight the importance of prompt diagnosis and intervention for hypermagnesemia and the need to regularly monitor magnesium levels in individuals receiving magnesium-containing preparations, especially those with impaired kidney function.

Multifaceted benefits of magnesium hydroxide dosing in sewer systems: Impacts on downstream wastewater treatment processes.

Magnesium hydroxide [Mg(OH)2] is a non-hazardous chemical widely applied in sewer systems for managing odour and corrosion. Despite its proven effectiveness in mitigating these issues, the impacts of dosing Mg(OH)2 in sewers on downstream wastewater treatment plants have not been comprehensively investigated. Through a one-year operation of laboratory-scale urban wastewater systems, including sewer reactors, sequencing batch reactors, and anaerobic sludge digesters, the findings indicated that Mg(OH)2 dosing in sewer systems had multifaceted benefits on downstream treatment processes. Compared to the control, the Mg(OH)2-dosed experimental system displayed elevated sewage pH (8.8±0.1vs 7.1±0.1), reduced sulfide concentration by 35.1%±4.9% (6.7±0.9mgSL-1), and lower methane concentration by 58.0%±4.9% (19.1±3.6mgCODL-1). Additionally, it increased alkalinity by 16.3%±2.2% (51.9±5.4mgCaCO3L-1), and volatile fatty acids concentration by 207.4%±22.2% (56.6±9.0mgCODL-1) in sewer effluent. While these changes offered limited advantages for downstream nitrogen removal in systems with sufficient alkalinity and carbon sources, significant improvements in ammonium oxidation rate and NOx reduction rate were observed in cases with limited alkalinity and carbon sources availability. Moreover, Mg(OH)2 dosing in upstream did not have any detrimental effects on anaerobic sludge digesters. Magnesium-phosphate precipitation led to a 31.7%±4.1% reduction in phosphate concertation in anaerobic digester sludge supernatant (56.1±10.4mgPL-1). The retention of magnesium in sludge increased settleability by 13.9%±1.6% and improved digested sludge dewaterability by 10.7%±5.3%. Consequently, the use of Mg(OH)2 dosing in sewers could potentially reduce downstream chemical demand and costs for carbon sources (e.g., acetate), pH adjustment and sludge dewatering.

Polycarbosilane/Divinylbenzene-Modified Magnesium Hydroxide to Enhance the Flame Retardancy of Ethylene-Vinyl Acetate Copolymer.

The thermal decomposition product of magnesium hydroxide (MH) is magnesium oxide (MgO), which serves as the foundational material for fireproof layer construction in the condensed phase. However, the weak interaction force between particles of MgO generated by thermal decomposition leads to the insufficient strength and poor adhesion ability of the fireproof layer. The fireproof layer was easily damaged and detached in this study, resulting in the low flame-retardant efficiency of MH. In this work, polycarbosilane (PCS) and divinyl benzene (DVB) were used to modify MH, and EVA/MH/PCS/DVB composites were made via melt blending. The flame-retardant properties of EVA/MH/PCS/DVB were evaluated using the limiting oxygen index (LOI), vertical combustion (UL-94), and a cone calorimeter (CONE). The thermal stability of the composites and flame retardants was analyzed using a thermogravimetric analyzer. The char layer structure was observed and analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the LOI of the EVA/MH/PCS/DVB with 50 wt.% flame retardants in total was as high as 65.1, which increased by 160% in comparison with EVA/MH. Furthermore, the total smoke production (TSP) of the EVA/MH/PCS/DVB composite decreased by 22.7% compared to EVA/MH/PCS; the thermal stability of the MH/PCS/DVB and EVA/MH/PCS/DVB improved to some extent; and the compact residual char after the combustion of EVA/MH/PCS/DVB had fewer cracks due to the adhesive effect induced by PCS/DVB.

Effect of Different Compatibilizers on the Mechanical, Flame Retardant, and Rheological Properties of Highly Filled Linear Low-Density Polyethylene/Magnesium Hydroxide Composites.

Maleic anhydride-modified homopolymerized polypropylene (PP-g-MAH) and maleic anhydride-modified polyolefin elastomer (POE-g-MAH) were used as bulking agents to improve the poor processing and mechanical properties of highly filled composites due to high filler content. In this study, a series of linear low-density polyethylene (LLDPE)/magnesium hydroxide (MH) composites were prepared by the melt blending method, and the effects of the compatibilizer on the mechanical properties, flame retardancy, and rheological behavior of the composites were investigated. The addition of the compatibilizer decreased the limiting oxygen index (LOI) values of the composites, but they were all greater than 30.00%, which belonged to the flame retardant grade. Mechanical property tests showed that the addition of the compatibilizer significantly increased the tensile and impact strengths of the LLDPE/60MH (MH addition of 60 wt%) composites. Specifically, the addition of 5 wt% POE-g-MAH increased 154.07% and 415.47% compared to the LLDPE/60MH composites, respectively. The rotational rheology test showed that the addition of the compatibilizer could effectively improve the processing flow properties of the composites. However, due to the hydrocarbon structure of the compatibilizer, its flame retardant properties were adversely affected. This study provides a strategy that can improve the processing and mechanical properties of highly filled composites.

Synthesis and Characterization of Doped Magnesium Hydroxide for Medium Heat Storage Application.

The amount of waste heat generated annually in the UK exceeds the total annual electricity demand. Hence, it is crucial to effectively harness all available sources of waste heat based on their varying temperatures. Through suitable technologies, a substantial portion of this waste heat has the potential to be recovered for reutilization. Thermochemical energy storage (TCES) provides the best opportunities to recover waste heat at various temperatures for long-term storage and application. The potential of TCES with magnesium hydroxide, Mg(OH)2, has been established, but it has a relatively high dehydration temperature, thus limiting its potential for medium-temperature heat storage applications, which account for a vast proportion of industrial waste heat. To this end, samples of doped Mg(OH)2 with varying proportions (5, 10, 15, and 20 wt%) of potassium nitrate (KNO3) have been developed and characterized for evaluation. The results showed that the Mg(OH)2 sample with 5 wt% KNO3 achieved the best outcome and was able to lower the dehydration temperature of the pure Mg(OH)2 from about 317 °C to 293 °C with an increase in the energy storage capacity from 1246 J/g to 1317 J/g. It also showed a monodisperse surface topology and thermal stability in the non-isothermal test conducted on the sample and therefore appears to have the potential for medium heat storage applications ranging from 293 °C to 400 °C.

Multifunctional PDO Thread Coated with Mg(OH)2/ZnO Nanoparticles and Asiaticoside for Improved Facial Lifting.

As interest in skin aesthetics increases, treatments to suppress aging are increasing. Among them, a facelift is the most effective procedure for improving wrinkles. However, side effects including inflammatory reactions occur due to the limitations of the PDO thread itself used during the procedure. In this paper, to improve the function of PDO thread, inorganic particles such as magnesium hydroxide (MH) and zinc oxide (ZO) and a biologically active agent, asiaticoside, were coated on the surface of PDO thread using ultrasonic coating technology. The coated thread exhibited excellent biocompatibility, promoted collagen synthesis, reduced inflammation, and stimulated angiogenesis in vitro and in vivo. The multifunctional PDO thread has shown promising potential for skin regeneration without inducing fibrosis. Such a practical coating system and the developed multifunctional PDO thread suggest new possibilities for developing safer and more effective materials in cosmetic and regenerative medicine to prevent aging and improve skin aesthetics.

Can dietary magnesium sources and buffer change the ruminal microbiota composition and fermentation of lactating dairy cows?

Magnesium oxide (MgO) is one of the most used Mg supplements in livestock. However, to avoid relying upon only one Mg source, it is important to have alternative Mg sources. Therefore, the objective of this study was to evaluate the effects of the interaction of two Mg sources with buffer use on the ruminal microbiota composition, ruminal fermentation, and nutrient digestibility in lactating dairy cows. Twenty lactating Holstein cows were blocked by parity and days in milk into five blocks with four cows each, in a 2 × 2 factorial design. Within blocks, cows were assigned to one of four treatments: 1) MgO; 2) MgO + Na sesquicarbonate (MgO+); 3) calcium-magnesium hydroxide (CaMgOH); 4) CaMgOH + Na sesquicarbonate (CaMgOH+). For 60 d, cows were individually fed a corn silage-based diet, and treatments were top-dressed. Ruminal fluid was collected via an orogastric tube, for analyses of the microbiota composition, volatile fatty acids (VFA), lactate, and ammonia nitrogen (NH3-N). The microbiota composition was analyzed using V4/16S rRNA gene sequencing, and taxonomy was assigned using the Silva database. Statistical analysis was carried out following the procedures of block design analysis, where block and cow were considered random variables. Effects of Mg source, buffer, and the interaction between Mg Source × Buffer were analyzed through orthogonal contrasts. There was no interaction effect of the two factors evaluated. There was a greater concentration of NH3-N, lactate, and butyrate in the ruminal fluid of cows fed with CaMg(OH)2, regardless of the buffer use. The increase in these fermentation intermediates/ end-products can be explained by an increase in abundance of micro-organisms of the genus Prevotella, Lactobacillus, and Butyrivibrio, which are micro-organisms mainly responsible for proteolysis, lactate-production, and butyrate-production in the rumen, respectively. Also, dietary buffer use did not affect the ruminal fermentation metabolites and pH; however, an improvement of the apparent total tract digestibility of dry matter (DM), organic matter (OM), neutral fiber detergent (NDF), and acid fiber detergent (ADF) were found for animals fed with dietary buffer. In summary, there was no interaction effect of buffer use and Mg source, whereas buffer improved total tract apparent digestibility of DM and OM through an increase in NDF and ADF digestibility and CaMg(OH)2 increased ruminal concentration of butyrate and abundance of butyrate-producing bacteria.

Magnesium oxide (MgO) is extensively used as a dietary magnesium (Mg) source in dairy cow diets. However, dairy operations can benefit from other Mg sources. Thus, we evaluated the replacement of dietary MgO with calcium­magnesium hydroxide (CaMg(OH)2) in diets with and without ruminal buffer and their effects on the ruminal microbiota composition, ruminal fermentation, and nutrient digestibility in lactating dairy cows. The study used 20 lactating Holstein cows that were blocked in groups of four and randomly assigned to one of the four treatments. The ruminal content, feed, feces, and urine were collected for analysis of the microbiota composition, ruminal fermentation, nitrogen metabolism, and apparent nutrient digestibility. There was no interaction effect of dietary buffer use and Mg source, while buffer improved total tract apparent digestibility of the dry matter and fiber components; CaMg(OH)2 increased the ruminal concentration of butyrate and the abundance of butyrate-producing bacteria. In summary, we conclude that using CaMg(OH)2 can improve ruminal fermentation regardless of buffer use, which indicates that we can take advantage of the mineral formulation in the diet to modulate the ruminal microbiota composition.

Effect of Functionalized Polyethylene Wax on the Melt Processing and Properties of Highly Filled Magnesium Hydroxide/Linear Low-Density Polyethylene Composites.

The poor processing and rheological properties of highly filled composites caused by the high loading of fillers can be improved with the use of maleic anhydride grafted polyethylene wax (PEWM) as compatibilizer and lubricant. In this study, two PEWMs with different molecular weights were synthesized by melt grafting, and their compositions and grafting degrees were characterized by Fourier transform infrared (FTIR) spectroscopy and acid-base titration. Subsequently, magnesium hydroxide (MH)/linear low-density polyethylene (LLDPE) composites with 60 wt% of MH were prepared using polyethylene wax (PEW) and PEWM, respectively. The equilibrium torque and melt flow index tests indicate that the processability and fluidity of MH/MAPP/LLDPE composites are significantly improved with the addition of PEWM. The addition of PEWM with a lower molecular weight leads to a substantial reduction in viscosity. The mechanical properties are also increased. The limiting oxygen index (LOI) test and cone calorimeter test (CCT) show that both PEW and PEWM have adverse effects on flame retardancy. This study provides a strategy to simultaneously improve the processability and mechanical properties of highly filled composites.

Mechanisms Underlying the Suppression of IL-1ß Expression by Magnesium Hydroxide Nanoparticles.

In recent years, magnesium hydroxide has been widely studied due to its bioactivity and biocompatibility. The bactericidal effects of magnesium hydroxide nanoparticles on oral bacteria have also been reported. Therefore, in this study, we investigated the biological effects of magnesium hydroxide nanoparticles on inflammatory responses induced by periodontopathic bacteria. Macrophage-like cells, namely J774.1 cells, were treated with LPS derived from Aggregatibacter actinomycetemcomitans and two different sizes of magnesium hydroxide nanoparticles (NM80/NM300) to evaluate their effects on the inflammatory response. Statistical analysis was performed using an unresponsive Student's t-test or one-way ANOVA followed by Tukey's post hoc test. NM80 and NM300 inhibited the expression and secretion of IL-1ß induced by LPS. Furthermore, IL-1ß inhibition by NM80 was dependent on the downregulation of PI3K/Akt-mediated NF-κB activation and the phosphorylation of MAPK molecules such as JNK, ERK1/2, and p38 MAPK. By contrast, only the deactivation of the ERK1/2-mediated signaling cascade is involved in IL-1ß suppression by NM300. Although the molecular mechanism involved varied with size, these results suggest that magnesium hydroxide nanoparticles have an anti-inflammatory effect against the etiologic factors of periodontopathic bacteria. These properties of magnesium hydroxide nanoparticles can be applied to dental materials.

Hydrophobic, Mechanical, and Physical Properties of Polyurethane Nanocomposite: Synergistic Impact of Mg(OH)2 and SiO2.

Polyurethane (PU) is one of the most well-known polymer coatings because of its favorable characteristics, which include its low density, nontoxicity, nonflammability, longevity, adhesion, simple manufacture, flexibility, and hardness. However, PU does come with several major drawbacks, among which are poor mechanical properties as well as low thermal and chemical stability, particularly in the high-temperature mode, where becomes gets flammable and loses adhesion ability. The limitations have inspired researchers to develop a PU composite to improve the weaknesses by adding different reinforcements. Magnesium hydroxide, having the ability to be produced with exceptional properties such as flammability, has consistently attracted the interest of researchers. Additionally, silica nanoparticles with high strength and hardness are one of the excellent reinforcements of polymers these days. The hydrophobic, physical, and mechanical properties of pure polyurethane and the composite type (nano, micro, and hybrid) fabricated with the drop casting method were examined in this study. 3-Aminopropyl triethoxysilane was applied as a functionalized agent. To confirm that hydrophilic particles turned into hydrophobic, FTIR analysis was carried out. The impact of size, percentage, and kind of fillers on different properties of PU/Mg(OH)2-SiO2 was then investigated using different analyses including spectroscopy and mechanical and hydrophobicity tests. The resultant observations demonstrated that different surface topographies can be obtained from the presence of particles of different sizes and percentages on the hybrid composite's surface. Surface roughness allowed for exceptionally high water contact angles, which confirmed the hybrid polymer coatings' superhydrophobic properties. According to the particle size and content, the distribution of fillers in the matrix also improved the mechanical properties.

Effect of an Antacid (Aluminum Hydroxide/Magnesium Hydroxide/Simethicone) or a Proton Pump Inhibitor (Omeprazole) on the Pharmacokinetics of Tebipenem Pivoxil Hydrobromide (TBP-PI-HBr) in Healthy Adult Subjects.

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is a novel oral carbapenem prodrug being developed for the treatment of serious bacterial infections. This open-label, 3-period, fixed sequence study evaluated the effect of gastric acid-reducing agents, aluminum hydroxide/magnesium hydroxide/simethicone, and omeprazole on the pharmacokinetics (PK) of tebipenem (TBP), the active moiety, following coadministration with immediate release TBP-PI-HBr during fasting. In Period 1, subjects received a single oral dose of TBP-PI-HBr 600 mg (2 × 300 mg tablets). In Period 2, subjects received a single oral dose of aluminum hydroxide 800 mg/magnesium hydroxide 800 mg/simethicone 80 mg suspension co-administered with a single dose of TBP-PI-HBr 600 mg. In Period 3, subjects received a single oral dose of omeprazole 40 mg once daily over 5 days, followed by single dose administration of TBP-PI-HBr 600 mg on day 5. In each period, whole blood samples were obtained prior to, and up to 24 h, following TBP-PI-HBr dose administration in order to characterize TBP PK. A 7-day washout was required between periods. Twenty subjects were enrolled and completed the study. Following co-administration of TBP-PI-HBr with either aluminum hydroxide/magnesium hydroxide/simethicone or omeprazole, total TBP exposure (area under the curve [AUC]) was approximately 11% (geometric mean ratio 89.2, 90% confidence interval: 83,2, 95.7) lower, and Cmax was 22% (geometric mean ratio 78.4, 90% confidence interval: 67.9, 90.6) and 43% (geometric mean ratio 56.9, 90% confidence interval: 49.2, 65.8) lower, respectively, compared to administration of TBP-PI-HBr alone. Mean TBP elimination half-life (t1/2) was generally comparable across treatments (range: 1.0 to 1.5 h). Concomitant administration of TBP-PI-HBr with omeprazole or aluminum hydroxide/magnesium hydroxide/simethicone is not expected to impact the efficacy of TBP-PI-HBr, as there is minimal impact on TBP plasma AUC, which is the pharmacodynamic driver of efficacy. Co-administration was generally safe and well tolerated.

Magnesium Hydroxide Nanoparticles Inhibit the Biofilm Formation of Cariogenic Microorganisms.

Although various caries-preventive agents have been developed, dental caries is still a leading global disease, mostly caused by biological factors such as mutans streptococci. Magnesium hydroxide nanoparticles have been reported to exhibit antibacterial effects; however, they are rarely used in oral care practical applications. In this study, we examined the inhibitory effect of magnesium hydroxide nanoparticles on biofilm formation by Streptococcus mutans and Streptococcus sobrinus-two typical caries-causing bacteria. Three different sizes of magnesium hydroxide nanoparticles (NM80, NM300, and NM700) were studied, all of which inhibited biofilm formation. The results showed that the nanoparticles were important for the inhibitory effect, which was not influenced by pH or the presence of magnesium ions. We also determined that the inhibition process was mainly contact inhibition and that medium (NM300) and large (NM700) sizes were particularly effective in this regard. The findings of our study demonstrate the potential applications of magnesium hydroxide nanoparticles as caries-preventive agents.