Magnesium Hydroxide Research Articles

Biosynthesis and biological activities of magnesium hydroxide nanoparticles using Tinospora cordifolia leaf extract.

The synthesis of magnesium hydroxide nanoparticles (Mg(OH)2 NPs) using plant extracts are known to be a practical, economical, and an environmentally friendly approach. In this work, Mg(OH)2 NPs were synthesized using aqueous leaf extract of Tinospora cordifolia, a medicinal plant commonly found in India. The synthesized Mg(OH)2 NPs were characterized using various spectroscopic techniques. The ultraviolet-visible (UV-Vis) absorption peak of the Mg(OH)2 NPs was detected at 289nm, Fourier transform infrared (FTIR) analysis confirmed the presence of various functional groups, and X-ray diffraction (XRD) patterns revealed the well-crystallized structure of the Mg(OH)2 NPs. High-resolution transmission electron microscopy (HR-TEM) and scanning electron microscopy (SEM) analyses depicted spherical morphology and an average particle size (PS) of 27.71nm. The energy-dispersive X-ray (EDX) analysis confirmed the presence of C, O, and Mg elements, and the X-ray photoelectron spectroscopy (XPS) survey spectrum confirmed the elements for the Su 1s peak at 280.2eV. The dynamic light scattering (DLS) analysis displayed an average PS of 54.3nm, and the Zeta potential (ZP) was of 9.89mV. The fabricated Mg(OH)2 NPs displayed notable antibacterial activity against S. epidermidis, E. coli, and S. aureus. In addition, these NPs exhibited strong antioxidant properties (> 75%) based on DPPH, ABTS, and hydrogen peroxide (H2O2) assays. Further, the same NPs exerted a potent anti-inflammatory activity (> 65%) based on COX-1 and COX-2 evaluations. The anti-Alzheimer' disease (AD) potential of Mg(OH)2 NPs was assessed through effective inhibition (> 70%) of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities. Molecular docking (MD) studies confirmed that caryophyllene has higher binding affinity with AChE (-5.3kcal/mol) and BuChE (-6.4kcal/mol) enzymes. This study emphasizes the green synthesis of Mg(OH)2 NPs using T. cordifolia as a plant source and highlights their potential for biomedical applications.

Preparation of high-purity magnesia spinel refractory raw materials with spinel-wrapped periclase structures using bischofite from salt lake

A large amount of bischofite is produced in the process of potassium extraction from salt lake, which seriously affects the ionic balance of brine system. In this study, a high-purity magnesia spinel refractory raw material with a spinel-wrapped periclase structure was directly prepared using bischofite by a precipitation-sintering approach. A coupling process of one-time crude magnesium chloride solution recrystallization and three-time precipitates washing was employed to remove crucial impurities (sodium, potassium, boron, etc.) and prepare the magnesium hydroxide precipitates with a high purity of 99.37 %. The lightly calcined magnesia gained from the high-purity magnesium hydroxide precipitates and white corundum were then employed for preparing the refractory raw materials. The effects of particle size and dosage of white corundum on the phase distribution, microstructure, and physical properties of the materials were thoroughly studied. The results illustrated that the prepared refractory raw materials were mainly composed of periclase and spinel phases, showing a distinct spinel-wrapped periclase structure that could enhance the physical properties. Therefore, the prepared refractory raw materials showed a high bulk density of 3.46 g·cm−3, a low apparent porosity of 2.46 %, and a linear shrinkage rate of 12.33 %, under the optimum conditions of white corundum particle size of 3.00 μm and alumina/magnesia mass ratio of 3:10.

Preparation of nano magnesium oxide by mechanochemical method using magnesium chloride

Magnesium chloride is a magnesium resource that is widely present in seawater and salt lakes. Therefore, the use of magnesium chloride is of great significance for the low-cost preparation of high-performance magnesium materials. In this work, mechanical ball milling was used for the preparation of magnesium oxide nanoparticles from magnesium chloride. Ball milling improves the unevenness of the reaction process and generates magnesium oxide with a more uniform particle size distribution. First, a magnesium chloride complex was obtained by heating and evaporating a mixture of magnesium chloride and ethanol with a mass ratio of 1:2 at 110 °C. Next, pure magnesium hydroxide with a smaller crystal size was obtained by ball milling the prepared magnesium chloride complex with calcium hydroxide at 600 rpm for 3 h. Finally, the magnesium hydroxide was calcined at 1000 °C for 60 min to obtain nano magnesium oxide particles with a particle size of 670 nm.

Multifunctional vitamin D-incorporated PLGA scaffold with BMP/VEGF-overexpressed tonsil-derived MSC via CRISPR/Cas9 for bone tissue regeneration

Guiding endogenous regeneration of bone defects using biomaterials and regenerative medicine is considered an optimal strategy. One of the effective therapeutic approaches involves using transgene-expressed stem cells to treat tissue destruction and replace damaged parts. Among the various gene editing techniques for cells, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) is considered as a promising method owing to the increasing therapeutic potential of cells by targeting specific sites. Herein, a vitamin D-incorporated poly(lactic-co-glycolic acid) (PLGA) scaffold with bone morphogenetic protein 2 (BMP2)/vascular endothelial growth factor (VEGF)-overexpressed tonsil-derived MSCs (ToMSCs) via CRISPR/Cas9 was introduced for bone tissue regeneration. The optimized seeding ratio of engineered ToMSCs on the scaffold demonstrated favorable immunomodulatory function, angiogenesis, and osteogenic activity in vitro. The multifunctional scaffold could potentially support stem cell in vivo and induce the transition from M1 to M2 macrophage with magnesium hydroxide and vitamin D. This study highlights the improved synergistic effect of a vitamin D-incorporated PLGA scaffold and a gene-edited ToMSCs for bone tissue engineering and regenerative medicine.

Efficient and fast arsenate removal from water by in-situ formed magnesium hydroxide

MgO nanoparticles have good As-adsorption capacity in treating As-contaminated wastewater but suffer from high production cost. In this study, instead of using pre-formed MgO nanoparticles, we found that in-situ formed Mg(OH)2 from MgCl2 and NaOH reaction exhibited super high arsenate (As(V)) removal efficiency. Only 1.5 mmol/L of in-situ formed Mg(OH)2 could remove more than 95% As(V) within 10 min to make the As contaminated water (10 mg-As(V)/L) meet the municipal wastewater treatment standard, whereas MgO nanoparticles failed. The Mg-As sludge has an amorphous crystal structure while no Mg(OH)2 phase could be observed. As(V) existed uniformly within the sludge which was confirmed by elemental mapping. A precipitation-adsorption-coagulation mechanism might exist, which could relieve the restriction of limited surface area of solid MgO adsorbents. This study not only reveals an applicable method for efficient removal of trace level As(V) from water but also implies the huge potential of in-situ formed adsorbents in water treatment.

A comprehensive study on dry sliding wear and in-vitro degradation of AZ31 composite with 6 wt% Sn and 1.5 wt% TiO2 fabricated by stir casting

Abstract This experimental study investigates the dry sliding wear behaviour of novel AZ31 composite with 6 wt% Sn and 1.5 wt% TiO2 samples, focusing on the influence of sliding distance and normal load. Additionally, the research examines degradation rates during a 120-hour immersion period in simulated body fluid (SBF). The wear volume loss increased significantly with higher loads and longer sliding distances, showing a 142% rise from 1000 m to 2000 m and 76% from 2000 m to 3000 m under a 5 N load, peaking at a 25 N load over 5000 m. The specific wear rate dropped by 39% from 5 N to 15 N but increased with distance due to thermal softening, while the coefficient of friction decreased from 0.284 at 1000 m to 0.213 at 5000 m under 5 N. FESEM analysis revealed a transition from abrasive to delamination wear, with a protective oxide layer forming during sliding. Sn in the composite formed hard Mg2Sn intermetallic compounds, affecting crack formation and propagation under higher loads. Wear debris analysis showed both abrasive and delamination wear mechanisms, highlighting the protective role of the oxide layer. The degradation rate increased rapidly during the initial immersion stage in simulated body fluid (SBF), reaching 15.9 mm year−1 after 24 h, and then stabilizing after 48 h. Hydrogen evolution rose sharply from 0.28 ml cm−12 at 2 h to 7.6 ml cm−12 within 24 h, with a 92% increase by 48 h and an additional 38% increase from 48 to 72 h. Post-immersion FESEM analysis showed corroded surfaces with protective layers, cracks, and pitting corrosion. Magnesium hydroxide (Mg(OH)2) and hydroxyapatite played crucial roles in inhibiting corrosion. This analysis provides insights into the wear, and degradation dynamics of the AZ31-6Sn/1.5TiO2 composite, with implications for engineering applications and the development of biodegradable implants in biomedical fields.

Synthesis of magnesium hydroxide flame retardant based on microcrystalline magnesite and its application in epoxy resin

Abstract A nanoscale hexagonal flake magnesium hydroxide (MH) flame retardant was prepared by a hydrothermal method using Tibetan microcrystalline magnesite as the raw material. The synthesized samples were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FSEM), thermogravimetric analysis-differential scanning calorimetry (TG-DSC), and laser particle size analysis. When subjected to hydrothermal treatment at 180 °C for a duration of 8 h in a solution containing 6 mol l−1 NaOH, and with the incorporation of 4 wt% of the surfactant polyethylene glycol 2000 (PEG2000), hexagonal flake MH, possessing an average particle size of 378.3 nm, was successfully synthesized. The study conducted an examination of the thermal, mechanical, and flame-retardant properties of both EP and EP/MH composites. The results revealed that the incorporation of 9 wt% MH led to a notable reduction in the peak heat release rate, total smoke production, and mass loss rate of the EP/MH composites by 36%, 14.5%, and 33.3% respectively, as compared to the pure EP. Remarkably, the tensile and flexural strength of the composite exhibited minimal impact.

Electrodeposition of calcareous cement from seawater in marine silica sands

The erosion of marine sediments is a pressing issue for coastal areas worldwide. Established methods to mitigate coastal erosion fail to provide lasting and sustainable solutions to protect marine ecosystems. Here we demonstrate the application of mild electrical stimulations to precipitate calcareous mineral binders from seawater in the pores of marine soils via electrodeposition, an alternative approach to mitigating coastal erosion. Results of electrochemical laboratory experiments unveil that the polymorphs, precipitation sites, intrusion mechanisms, and effects of electrodeposited minerals in marine sands vary as a function of the magnitude and duration of applied voltage, soil relative density, and electrolyte ionic concentration. Surprisingly, in addition to the precipitation of calcium carbonate and magnesium hydroxide, the formation of hydromagnesite is also observed due to electrically driven fluctuations in the local pH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${pH}$$\\end{document}. These electrodeposits lead to enhanced mechanical and hydraulic properties of the marine sands, indicating that electrodeposition routes could be developed to reinforce marine soils in coastal areas that more closely mimic natural systems.

Aging assessment of silicone rubber materials under corona discharge accompanied by humidity and UV radiation

Abstract High voltage (HV) outdoor insulators are subjected to both electrical and environmental stresses, which may lead to their failure. Among the causes, corona discharge, humidity and UV radiation are considered to be the most damaging factors. Efforts are therefore underway to investigate new materials for improving the performance of insulating systems. In this research work, silicone-based room temperature vulcanized samples filled with alumina trihydrate (ATH), silicon dioxide and magnesium hydroxide (MH) were prepared and exposed to AC corona discharge for a duration of 110 h. The electric discharge was also accompanied by UV radiation and two different humidity levels. Following aging of the test samples, diagnosis was conducted to assess their integrity. Measurements based on determining the static contact angle demonstrated the loss of hydrophobicity of all the materials, while hydrophobicity recovery phenomena revealed that ATH-doped materials demonstrated a comparatively higher increase in the contact angle than in samples filled with silicone dioxide (silica) and MH. Scanning electron microscopy analysis revealed deep cracks and block-like structures on their surfaces. Similarly, energy-dispersive X-ray analysis indicated the signs of surface oxidation of the aged samples. However, the data of elemental composition exhibited the loss of filler contents as well as that of carbon from the base matrix. The overall assessment showed that resistance to suppress aging is influenced by both the filler type and its concentration in the investigated composites. The ATH-filled composites exhibited outstanding performance when exposed to the rigors of corona discharge and other environmental stresses. This research contributes to materials science and HV engineering by addressing the development of composites for enhanced insulator performance, with future aspects lying in the utilization of nano-composites for advanced functionality and durability.

Carbon nano-tube coated with iron carbide catalysis for hydrolysis of magnesium to generate hydrogen

Hydrolysis of magnesium (Mg) or their composites are considered as an efficient, economical and enabling technique to produce hydrogen (H2). In this study, carbon nano-tube coated with iron carbide (CNT@Fe3C) was synthesized and applied as a catalyst to promote hydrolysis of Mg to generate H2. Ball milling technique was employed to prepare Mg-Xwt%CNT@Fe3C (X = 0.2, 2.0, 5.0 and 10.0) composites for hydrolysis in seawater. Among employed composites, the results demonstrated that the introduction of small amount of CNT@Fe3C promote the hydrolysis kinetics of Mg. Particularly, Mg-5.0 wt%CNT@Fe3C composite ball milled for 1 h released 866.5 mL/g H2 with 10072.0 mLg−1min−1 initial hydrogen generation rate mHGR and demonstrated an excellent composite. Furthermore, activation energy of Mg hydrolysis kinetic dropped to 23.6 kJ/mol. Hence, CNT@Fe3C inhibited the magnesium hydroxide (Mg(OH)2) from sticking to the unreacted Mg surfaces, which enhanced its galvanic corrosion and reactivity. In order to develop portable H2 generators, CNT@Fe3C supported Mg system can provide clean H2 to reduce the adverse environmental effect.

A new application of MoS2@AG@PA prepared by irradiation: Synergizing with magnesium hydroxide to enhance fire safety and other key properties of EVA composites

AbstractTwo‐dimensional molybdenum disulfide (MoS2) nanosheets are seen as highly promising nanofillers for enhancing polymer properties, yet there is a need for methods that are low‐cost, simple, and environmentally friendly to facilitate the large‐scale production of MoS2 nanosheets. Furthermore, it is necessary to functionalize the MoS2 surface to ensure good interfacial compatibility with the polymer matrix. In this study, MoS2@Ag@PA hybrids were created by generating silver nanoparticles directly on the surface of MoS2 via radiation, followed by encapsulation on the surface of MoS2@Ag through the chelating properties of phytic acid. It is significant to note that, due to the excellent lubrication and physical cross‐linking effects of the MoS2@Ag@PA hybrids, adding one part of MoS2@Ag@PA hybrids can enhance the melt flow rate and elongation at break of the ethylene vinyl acetate copolymer (EVA)/MH composites by 140% and 17.3%, respectively. The simultaneous addition of one part of MoS2@Ag@PA hybrids decreased the peak heat release rate, total heat release, and total smoke release of the EVA composites by 48.7%, 42.7%, and 41.2%, respectively. Moreover, the toxic gasses (e.g., CO) generated by burning EVA composites were significantly reduced compared to pure EVA, indicating improved fire safety. This research not only provides significant opportunities for the green mass production of MoS2 nanosheets but also expands their potential applications in high‐performance nanocomposites.

Development and characteristic research on new thermal insulation and anti-permeability grouting material for tunnels in cold regions

The surrounding rock of tunnels in cold regions are susceptible to the freeze–thaw cycle resulting from the combination of low temperatures and moisture during tunnel service. The phenomenon will not only lead to the expansion of pores and fissures in the surrounding rock of the initial tunnel, but also destroy the integrity of the rock. This destruction will have a serious impact on tunnel structure and rail transit operation safety. At present, the commonly used thermal insulation measures have some problems such as maintenance difficulties, low economic efficiency, and safety hazards. Therefore, it is urgent to develop a kind of tunnel maintenance grouting material with insulation and anti-permeability, which has the characteristics of simple operation, easy preparation and application. We independently developed a composite grouting material composed of polyurethane (PU), epoxy resin (E-51) and acrylic powder (PMMA). Through the material combustion test, magnesium hydroxide was selected as the flame retardant additive. Moreover, we measured the thermal conductivity, water absorption, apparent density, porosity and strength characteristic parameters. The thermal insulation and anti-permeability characteristics of the composites were also analyzed. The results indicated that the thermal conductivity of the new composite grouting material is 6.3% lower than the PU before adding flame retardant. Compared with the PU with flame retardant, the water absorption decreased by 74.4% and the ultimate strength increased by 33.3%. For the area with an average temperature lower than − 10 °C, we recommend the ratio scheme of E-51: 3%; PMMA: 15%. For the area with high water content in the surrounding rock of the tunnel, we recommend the ratio scheme of E-51: 15%; PMMA: 3%. This study provides new ideas for material preparation and tunnel insulation methods for anti-freezing measures in tunnels during their operational period in cold regions.

Modelling of Sulfur Dioxide Removal by Seawater in a Flue Gas Desulfurization Absorber

Although Indonesia has set a target for increasing the use of renewable energy for electricity generation, the use of coal as a source of energy will still dominate at least until 2040. Sulfur dioxide (SO2) along with other gases and particulates released from the use of coal in coal-fired power plants (CFPPs) may cause air pollution. The use of seawater, an abundant source of absorbent in a maritime country such as Indonesia, in flue gas desulfurization (SWFGD) absorbers, is an economical option for treating SO2 in an absorption tower compared to other alkaline chemicals, e.g. limestone (CaCO3) or magnesium hydroxide (Mg(OH)2). A model, which correlates the equilibrium of the reaction with the salinity of the absorbent, was developed to predict the sulfur dioxide scrubbing process inside an SWFGD absorber. The simulation also took into account the mass and energy balance during the scrubbing process. The calibration using field SWFGD data showed a good correspondence between field data and modelling results.

In vitro degradation behavior of grain refined WE43 magnesium alloy for biodegradable temporary implant applications

AbstractIn the present work, grain‐refined WE43 magnesium alloy was produced by friction stir processing to investigate the in vitro degradation behavior targeted for temporary bone implant applications. Friction stir processing resulted in significant grain refinement (from 46±4.2 μm to 16.1±5.4 μm) as observed from microstructural studies. Increased wettability was observed from the contact angle measurements in grain‐refined WE43 alloy. The corrosion behavior of the base alloy and the grain refined alloy assessed by potentiodynamic polarization tests demonstrated the influence of the smaller grain size and decreased intermetallics on enhancing corrosion resistance. Immersion studies carried out in simulated body fluids for one week indicated a quick development of the protective magnesium hydroxide on the surface of grain‐refined WE43 alloy compared with the base alloy. The deposition of the mineral phases from the immersed solution on the surface of the samples was studied by scanning electron microscopy and x‐ray diffraction analysis to assess the effect of microstructure on the biomineralization. Promisingly, grain refined WE43 exhibited relatively excellent mineral deposition which further helped to control the degradation of the alloy. The weight loss measurements of the samples from the immersion tests were also in good agreement with the electrochemical test results. Hence, the results demonstrate the promising role of grain refinement by friction stir processing in tailoring WE43 magnesium alloy with better degradation behavior for temporary bone implant applications.

Phenolic resin-based nanoflower porous carbon synthesized by self-assembly of MgO hydrolysis for boosting supercapacitor performance

Although electrode materials with flower-like structures have showing promising achievement for battery energy storage for stable structure and rich specific surface area, there are still some challenges in precisely controlling their microstructure. Inspired by the hydrolysis and self-assembly of MgO into petal-like magnesium hydroxide crystals under alkaline critical micelle conditions, we have proposed to synthesize a unique phenolic resin with a 3D flower-like structure as a carbon precursor. After a series of treatments, the optimal sample consists of nanosheets (thickness ≈27 nm) extending in all directions from the core, with a porous structure, significant specific surface area of 2028 m2/g and pore volume of 1.79 m3/g. Electrochemical experiments confirmed that the sample exhibits satisfactory electrochemical performance as the electrode of supercapacitor. It shows an amazing unique capacitance of 320.1 F/g, and the charge–discharge capacity retention rate exceeds 94.6 % after 5000 cycles. Moreover, a high energy density of 9.44 Wh/kg at 126 W/kg is shown for the symmetrical supercapacitors. We believe that the 3D flower-like morphology formed by the unique lamellar structure can provide more active sites, promote ion transports and increase the stability of structure. These findings suggest a new strategy to control the morphology of phenolic resin-based carbon materials.

Fabrication of Y2O3-doped MgO refractory raw materials based on magnesium hydroxide from salt-lake brine

High-purity magnesia refractories were fabricated by brine magnesium hydroxide from the salt-lake brine (Qinghai Salt Lake) and Y2O3 as an additive at 1780 °C. It avoided the substantial CO2 emissions and ultra high temperature sintering process (＞1900 °C) when compared with the conventional magnesite-calcination technical approach. The results confirmed that Y2O3 was dispersed on the MgO grains boundaries in the fabricated MgO aggregates, resulting in a decrease in apparent porosity and enhancing the grains' boundaries. With 3 wt% addition of Y2O3, the apparent porosity and bulk density of the sample reached to 15.9 % and 3.10 g/cm3 from 37.9 % to 2.30 g/cm3 of blank control group, respectively. Compared to the blank control without Y2O3-adding, the sample with 5 wt% Y2O3 exhibited a 54.17 % increase in the resistance to molten slag. SEM results indicated that the incorporation of Y2O3 in samples increased the porosity of small pores and enhanced grains boundaries, thereby suppressing slag's penetration. Furthermore, the Y2O3-adding was employed to disperse the MgO grains boundaries and existed as separate phases for grains boundaries enhancement. The slag attack of the fabricated MgO–Y2O3 refractory raw materials were controlled by an inter-crystalline corrosion process.

Mechanical properties and stability of zinc-contaminated red clay cured by MICP synergistically activated MgO

Microbially Induced Carbonate Precipitation (MICP) technology offers an innovative approach for the solidification and stabilization of heavy metal-contaminated soils; However, the mechanical strength and long-term stability of this remediation method have not been thoroughly investigated. This study introduces an innovative curing and stabilization technique using MICP-activated MgO to address the geotechnical challenges posed by zinc ion-contaminated soils. To investigate the effect of zinc ions on soil and the optimal efficacy of MICP-activated MgO in curing zinc contamination, experiments were conducted on zinc-contaminated soils with varying zinc ion concentrations (0.05%, 0.1%, 0.5%, 1.0%), dry densities (1.35, 1.4, 1.45, 1.5g/cm³), and activated MgO admixtures (1%, 2%, 5%, 10%). The effectiveness of MICP-activated MgO was evaluated through macroscopic analysis and stability tests, including unconfined compressive strength tests, direct shear tests, and the Toxicity Characteristic Leaching Procedure (TCLP). The results indicated that zinc ions disrupted soil particle cementation, enlarged inter-particle pores, and significantly reduced both unconfined compressive strength and shear strength. The optimal dosage of MICP-activated MgO for curing zinc-contaminated soil was determined to be 10%, resulting in an unconfined compressive strength of 1.196MPa and a Zn2+ leaching concentration of 0.1414mg/L. The combined actions of MICP-activated MgO facilitated the formation of alkaline magnesium carbonate, calcium carbonate, and magnesium hydroxide. These compounds filled the inter-particle pores of zinc-contaminated soil, encapsulating and co-precipitating zinc ions, thereby enhancing the soil's strength and stability. These findings establish a theoretical foundation for the engineering application of MICP-activated MgO in the remediation of zinc-contaminated soils.

Relative availability of five inorganic magnesium sources in non-pregnant non-lactating Holstein cows.

Inorganic sources of Mg are commonly used in dairy cow diets, but their availability varies significantly. This study assessed the relative availability of 4 commonly used inorganic Mg sources and a novel alkalinizing proprietary mineral blend [PMB; Multesium (GLC Minerals, LLC, Green Bay, WI, USA)]. The study was a duplicated 6 × 6 Latin square, with 12 nonlactating, non-pregnant Holstein dairy cows assigned to a square based on BW and parity. Cows were fed 90% of their voluntary DMI (diet contained 0.21% Mg). Each experimental period lasted 7 d. On d 2 of each period, urinary catheters were fitted. Total urine collection started on d 3 for 48 h with samples collected and measured every 12 h. On d 4, 30 g of Mg were administered as boluses with gelatin capsules: negative control (one empty capsule), magnesium oxide (MgO), magnesium sulfate (MgSO4), calcium magnesium hydroxide [CaMg(OH)4], calcium magnesium carbonate [CaMg(CO3)2], and PMB [a blend of Ca and Mg sources that includes CaMg(CO3)2, CaMg(OH)4, and MgO]. Blood samples were collected at 0, 1, 2, 3, 12, and 24 h after treatment administration on d 4 of each treatment period. Urine and blood samples were analyzed for Mg and Ca concentration. Statistical analyses were conducted with PROC GLIMMIX including treatment, time, period, square, treatment × time, treatment × period, and time × period as fixed effects, and cow nested within square as a random effect in the model. Urinary Mg excretion for 4 of the Mg sources studied [PMB, MgO, CaMg(OH)4, and MgSO4] increased significantly, representing an increase of at least 40.8% relative to control. The supplementation of CaMg(CO3)2 did not significantly increase relative to control. There were no significant changes in blood Mg concentration with treatment; but, a significant treatment × time effect was observed. Calcium-rich sources [PMB, CaMg(OH)4, CaMg(CO3)2] had lower blood Mg concentrations at 12 or 24 h after treatment than control and CaMg(CO3)2. Based on urinary Mg excretion 24 h after treatment, 4 of the Mg sources evaluated (including PMB) showed a similar availability, however, the availability of the commercial CaMg(CO3)2 source included in our study was similar to the negative control (no-supplemented cows).

The Subduction of Hydrogen: Deep Water Cycling, Induced Seismicity, and Plate Tectonics

The dynamic equilibrium between mantle degassing and water recycling in subduction zones controls the variation of sea level in deep geologic time, as well as the size of Earth’s interior hydrogen reservoir. While the principles of water transport and water release by common hydrous minerals in the subducted crust are relatively well understood, the importance of deep serpentinization of the slab, the contribution of nominally anhydrous minerals and dense hydrous magnesium silicates to water transport, and the mechanisms of water subduction into the lower mantle are still subjects of active research. A quantitative understanding of these processes is required to constrain the evolution of Earth’s deep water cycle through geologic time and the role of water in stabilizing plate tectonics.

Biomimetic mineralization of hydrated magnesium carbonate for hydrogel reinforcement and heavy metal adsorption

With excessive Mn(Ⅱ) and Cu(Ⅱ) pollution in aquatic environments posing potential health risks to inhabitants, the emergence of carbon capture, utilization and storage (CCUS) technology has promoted the improvement of heavy metal remediation technologies. Using hydrothermal sediment as a crystal seed, rhamnolipid was used to mediate biomimetic mineralization to prepare hydrated magnesium carbonate (HMC) composites to enhance the Mn(Ⅱ)/Cu(Ⅱ) adsorption performance of alginate hydrogels. Hydrothermal sediment is beneficial for accelerating biomimetic mineralization, while rhamnolipid can induce a crystalline phase transformation from dypingite to nesquehonite. The addition of sediment significantly enhanced the compressive mechanical properties and thermal stability of the hydrogels. The adsorption performances of the nesquehonite and dypingite hydrogels were better for Mn(II) and Cu(II), respectively. An increase in the amount of sediment improved the adsorption of Cu(II) by the hydrogels appropriately, resulting in stronger selectivity for Cu(II). The adsorption of Mn(II) and Cu(II) on the hydrogel beads was thermodynamically spontaneous. The inhibitory effects of sodium dodecyl benzene sulfonate (SDBS), fulvic acid (FA) and alginate on Cu(II) adsorption were more obvious than those of bovine serum albumin (BSA). Both the complexation of functional groups on alginate and mineralization by HMC participated in the adsorption of Mn(II) and Cu(II).