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Magnesium phosphate ceramics are short of osteostimulation capacity to effectively repair the bone defects. Herein, magnesium silicate (MgSi) was utilized as an additive to modify the 3D-printed magnesium phosphate (MgP) ceramic scaffolds. The results presented that the addition of MgSi was conducive to enhancement of compressive strength of the MgP/MgSi ceramic composite scaffolds, and the scaffolds incorporating 20 wt% MgSi had the highest value. The degradation of MgP/MgSi scaffolds resulted in a decrease of mechanical strength and the continuous release of magnesium and silicon ions. In comparison with MgP scaffolds, the MgP/MgSi scaffolds promoted the growth and osteogenic gene expression of bone marrow mesenchymal stem cells. Collectively, the 3D-printed MgP/MgSi scaffolds with high mechanical strength and osteo-stimulation effects are potential biomaterials for the effective restoration of bone defects. [ABSTRACT FROM AUTHOR]

The slow formation of magnesium silicate hydrate (M-S-H) results in insufficient early strength of M-S-H cement, restricting its wide application. In this study, nanosilica (NS) was applied to modify the performance of M-S-H cement. The influence of NS on the mechanical performance and microstructure was investigated through compressive strength measurements, X-ray diffraction (XRD), derivative thermogravimetry (TG-DTG), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Mercury intrusion porosimetry (MIP). Subsequently, the hydration mechanism of the M-S-H cement was illustrated after adding NS. The results showed that NS could effectively improve the early strength of M-S-H cement. The compressive strength after 3 days of reaction increased by 59.8%, 130.7%, and 25.7% for 1.5%, 3.0%, and 4.5% NS addition, respectively. After curing for 28 days, the addition of 1.5% NS resulted in a 25.7% increase in compressive strength, whereas the enhancements for samples with 3.0% and 4.5% NS were minimal. NS quickly dissolved to form HSiO43- , H2SiO42- , and H3SiO4- , accelerating the formation of M-S-H and resulting in a higher early compressive strength of the sample. In this study, the novel concept of the addition of NS to M-S-H cement was proposed, which has significant value for the wider application of M-S-H cement in civil engineering. [ABSTRACT FROM AUTHOR]

The electrical conductivity of pure and Al/Fe‐bearing phase E was measured up to 950 K at 15 GPa using a complex impedance spectroscopy. Pure phase E shows comparable conductivity to that of phase D, and a few orders of magnitude higher than that of phase A and super‐hydrous phase B. Al‐bearing phase E does not exhibit a conductivity difference, while a certain amount of incorporated Fe prominently increases its electrical conductivity by a factor of 4. Unlike the sole substitution 2Al3+→Mg2++Si4+ in phase D and H, H+ is likely involved in the substitution. Proton conduction is the dominant conduction mechanism, while small polaron conduction becomes dominant with increasing Fe content. Phase E in subducted slabs at depth of the upper transition zone cannot explain the high electrical conductivity anomalies beneath the Philippine Sea or Northeast China. Other mechanisms such as dehydration of hydrous minerals is needed to account for them. Plain Language Summary: Some subduction zones exhibit anomalously higher electrical conductivity compared to the average value of mantle, which may be due to the existence of hydrous minerals, of free water from dehydration, or of a small fraction of melt. If it remains a relatively low temperature below the choke point inside the slab during descending, dense hydrous magnesium silicates are potential candidates explaining the high conductivity anomalies. Impedance spectroscopy experiments are effective way to determine the electrical conductivity of the hydrous minerals. Combined with multi‐anvil apparatus, and the results at high pressure and high temperature can be directly applied to Earth's mantle condition. In this study, we synthesized pure and Fe/Al bearing phase E and measured the electrical conductivity. The Fe/Al substitution mechanism and conduction mechanism have been discussed. Applying our conductivity results to the depth of upper transition zone, we found that the high conductivity anomalies cannot be explained by the existence of phase E. Therefore, other mechanisms are needed, such as an existence of free water from dehydration, or an existence of melt. Key Points: The electrical conductivity of pure and Al/Fe‐bearing phase E was measured up to 950 K at 15 GPaIncorporation of Fe prominently increases its electrical conductivity by a factor of 4Phase E in subducted slabs cannot explain the high electrical conductivity anomalies beneath the Philippine Sea or Northeast China [ABSTRACT FROM AUTHOR]

This study investigated the inclusion of magnesium silicate monohydrate (MSMH) crystal in MgO–SiO 2 mixes designed for extrusion-based 3D printing. Considering the adjustment and optimization of rheological properties are fundamental for the printability of cement pastes, the dynamic rheology, thixotropy and strength development of the prepared mixes were analyzed to characterize their fresh properties, workability, buildability, and mechanical performance. Furthermore, isothermal calorimetry, X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and scanning electron microscopy (SEM) were employed to investigate the phase composition and microstructural evolution of the pastes, with and without the presence of MSMH. Addition of MSMH at 2 % of the binder component significantly enhanced the plastic viscosity, dynamic yield stress and thixotropy. Pastes incorporating 2 % MSMH exhibited excellent structural build-up without affecting extrudability, with a minimal strain deformation in the printed structure. The compressive strength of all pastes exceeded 20 MPa after 3 days, reaching ∼50 MPa at 28 days with 2 % MSMH inclusion. The introduction of MSMH improved the peak heat flow measured by isothermal calorimetry and enhanced the formation and growth of hydration products after 7 days of curing, resulting in a more compact microstructure. [ABSTRACT FROM AUTHOR]

The preparation of di-calcium magnesium silicate Ca2MgSi2O7 doped with 0.5, 1.0, 1.5, 2.0 and 2.5 mol.% of erbium (III) using a solid state reaction method is reported. An X-ray diffraction pattern obtained from the sample at optimum photoluminescence (PL) emission intensity exhibits a quite prominent resemblance with the crystallographic open database (COD) with entry 96-900-6449. This confirms the valid preparation of tetragonal akermanite with a P-4 21 m (113) space group. A 980 nm laser source is used as an excitation radiation for recording the PL emission spectra. The emission spectra exhibit two distinguished prominent peaks centered at 534 and 623 nm. These peaks are attributed to the 2H11/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of erbium (III) ions respectively. The sample with 2.0 mol.% of erbium (III) exhibits an optimum PL intensity, and beyond this the concentration quenching occurs. The thermoluminescence studies of the same sample suggest an existence of the near second order kinetics. Therefore, the sample could be a very good candidate in LED applications. [ABSTRACT FROM AUTHOR]

Copyright of Menoufia Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study's aim is to fully characterize ferronickel slag from New Caledonia, considered a multiphase mineral containing amorphous material. The methodology consisted of combining chemical, mineral, and morphological characterization techniques, such as ICP-AES, TGA, Q-XRD, microscopy, spectroscopy, etc. The ferronickel slag consisted of 44 wt. % forsterite, with the inclusion of iron as a substitution for magnesium (Mg1.8Fe0.2SiO4), 1.7 wt. % chromite and 54 wt. % amorphous phase containing iron, magnesium, aluminum, and silica (Mg/Si = 0.4; Fe/Si = 0.2; Al/Si = 0.1). This material was slightly reactive in a cementitious medium, thus limiting its use as an SCM in the construction sector. The ferronickel slag was then subjected to an attrition-leaching carbonation process at 180 °C and a partial pressure of CO2 of 20 bar. The obtained product, carbonated at 80% of its capacity, was also characterized. It was composed of carbonates (37% of magnesite and 4% of siderite), remaining forsterite (7 wt. %), chromite (1 wt. %), and 50% of an amorphous phase, mainly composed of silica and aluminum. The complete characterization of those products helped in understanding the chemistry of the carbonation process and finding valorization paths for the carbonated products in the construction sector. The carbonated product may be used either as an SCM in blended cement or as a precursor of magnesium–silicate binders. [ABSTRACT FROM AUTHOR]

Sulfate-bearing soils is widely distributed around the world, and this type of soil is prone to rock and soil disasters such as dissolution, corrosion of foundations, and swell when exposed to water. Cement is a frequently used stabilizer to treat sulfate-bearing soils. However, sulfate-bearing soils usually include various types of sulfates, such as, calcium sulfate (CaSO4), sodium sulfate (Na2SO4), potassium sulfate (K2SO4), and magnesium sulfate (MgSO4). So far, the effect of sulfate type on the strength and swelling properties of sulfate-bearing soil stabilized with cement has not been clarified. Therefore, in this study, the strength and swelling properties of four sulfate-bearing soils treated with cement were studied using unconfined compressive strength tests, and swelling tests. X-ray diffraction (XRD), scanning electron microscopy, and inductively coupled plasma spectroscopy were employed to study mineralogical, micro-structural properties, and concentrations of calcium ion of stabilized soils, to explore stabilization mechanisms. The results showed that the formation of magnesium silicate hydrate and highest concentration of free Ca2+ in the stabilized Mg-sulfate-soil caused its lowest strength. The reduction in free Ca2+ concentration was greater in the stabilized Na-sulfate-soil and K-sulfate-soil compared to stabilized Mg-sulfate-soil and Ca-sulfate-soil, contributing to the formation of more calcium silicate hydrate and ettringite. Therefore, the stabilized Na-sulfate-soil and K-sulfate-soil had greater swelling and strength compared to other soils. As the cement content increases, there are abundant in the sulfated cement stabilized soil observed in XRD and SEM photos. Overall, sulfates with monovalent cations increased the strength of cement-stabilized soils more than those with divalent cations, while sulfates with divalent cations improved the resistance to swelling of cement-stabilized soils. Before treating sulfate-bearing soils with cement, it is necessary to first determine the cations type in the soil. If the soil contains Mg2+, seek cement alternatives. If the other three cations are present, choose an appropriate cement content for stabilization. This study provides some references for the stabilization of sulfate-bearing soils with cement. [ABSTRACT FROM AUTHOR]

Wound infections caused by Staphylococcus aureus often result in localized suppurative lesions that severely impede the healing process, so it is urgent to develop a dress with efficient antimicrobial and pro-healing functions. In this study, the bifunctional injectable hydrogel lactoferrin (Lf)/NZ2114/lithium magnesium silicate hydrogel (LMSH) was first successfully prepared through the electrostatic interaction method. The physical, biological, and efficacy properties are systematically analyzed with good shear-thinning capacity and biocompatibility. More importantly, it inhibits infection and promotes wound healing in a mouse wound infection model after 14 d treatment, and the bactericidal rate and healing rate were over 99.92% and nearly 100%, respectively. Meanwhile, the massive reduction of inflammatory cells, restoration of tissue structure, and angiogenesis in mice showed the anti-inflammatory and pro-healing properties of the hydrogel. The healed wounds showed thickening with more hair follicles and glands, suggesting that the hydrogel Lf/NZ2114/LMSH (Three in One) could be a better dressing candidate for the treatment of S. aureus-induced wound infections. [ABSTRACT FROM AUTHOR]

Magnesium silicate hydrate (M‐S‐H) represents a promising alternative to traditional cement, particularly for low‐pH construction applications such as nuclear waste encapsulation and carbon dioxide injection. The durability of construction materials, a critical aspect of their suitability for various purposes, is primarily governed by the kinetics of dissolution of the binder phase under service conditions. In this study, we employed in situ atomic force microscopy to assess the dissolution rates of M‐S‐H in water equilibrated with air. Quantitative analysis based on changes in volume and height revealed dissolution rates ranging from 0.18 to 3.09 × 10−12 mol/cm2/s depending on the precipitate Mg/Si ratio and morphology. This rate surpasses its crystalline analogs, talc (Mg3Si4O10(OH)2) and serpentine (Mg3(Si2O5)(OH)4), by about three to five orders of magnitude. Interestingly, oriented M‐S‐H dissolved faster than non‐oriented M‐S‐H. Spatially resolved assessments of dissolution rates facilitated a direct correlation between rates and morphology, showing that edges and smaller crystallites dissolve at a faster pace compared to facets and larger crystallites. The outcomes of this study provide insights into the mechanisms governing the dissolution of M‐S‐H and the factors dictating its durability. These findings hold implications for the strategic design and optimization of M‐S‐H for various applications. [ABSTRACT FROM AUTHOR]

This study’s aim is to fully characterize ferronickel slag from New Caledonia, considered a multiphase mineral containing amorphous material. The methodology consisted of combining chemical, mineral, and morphological characterization techniques, such as ICP-AES, TGA, Q-XRD, microscopy, spectroscopy, etc. The ferronickel slag consisted of 44 wt. % forsterite, with the inclusion of iron as a substitution for magnesium (Mg1.8Fe0.2SiO4), 1.7 wt. % chromite and 54 wt. % amorphous phase containing iron, magnesium, aluminum, and silica (Mg/Si = 0.4; Fe/Si = 0.2; Al/Si = 0.1). This material was slightly reactive in a cementitious medium, thus limiting its use as an SCM in the construction sector. The ferronickel slag was then subjected to an attrition-leaching carbonation process at 180 °C and a partial pressure of CO2 of 20 bar. The obtained product, carbonated at 80% of its capacity, was also characterized. It was composed of carbonates (37% of magnesite and 4% of siderite), remaining forsterite (7 wt. %), chromite (1 wt. %), and 50% of an amorphous phase, mainly composed of silica and aluminum. The complete characterization of those products helped in understanding the chemistry of the carbonation process and finding valorization paths for the carbonated products in the construction sector. The carbonated product may be used either as an SCM in blended cement or as a precursor of magnesium–silicate binders.

Copyright of Journal of Soil Sciences & Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the research for advanced materials suitable for high-temperature uses continues, the need for oxide ceramic micro-nanofibers with outstanding mechanical and thermal properties becomes increasingly important. By incorporating two types of magnesium sources, specifically Mg(CH 3 COO) 2 ·4H 2 O and MgCl 2 ·6H 2 O, into the precursor, a range of fibers made of magnesium silicate ceramics was produced through electrospinning. X-ray diffraction (XRD) analysis verified that the resulting multiple phases included MgO, MgSiO 3 , Mg 2 SiO 4 , and amorphous SiO 2 , with the phase composition being affected by the diffusion reaction of Mg ions. The fibers produced using the dual-precursor method maintained a stable morphology with a uniform and compact structure after undergoing high-temperature treatments ranging from 1000 to 1200 °C. This study is the first to report the tensile strength of magnesium silicate fibrous membranes, which was found to be 1.54 ± 0.27 MPa and 1.21 ± 0.73 MPa after heat treatment at 800 °C and 1000 °C, respectively. Furthermore, these fibrous membranes demonstrated dependable thermal insulation properties within the testing range of 500–1000 °C, along with a low thermal conductivity at room temperature of 0.0301–0.0306 W m−1·K−1. Characterized by their impressive mechanical strength and high temperature stability, magnesium silicate ceramic micro-nanofibers show significant potential for various applications in the targeted field. [ABSTRACT FROM AUTHOR]

Magnesium silicate ceramics are promising materials for bone tissue regeneration and can be prepared through 3D printing of magnesium oxide/silica (MgO/SiO2) cement pastes followed by calcination. Despite the growing interest in these formulations, additive manufacturing technology has only recently been explored for these cements, and the effects of admixtures and additives on such printing inks remain largely unexplored. In this study, we prepared various MgO/SiO2 cement formulations with differing amounts of sodium orthophosphate, a setting retarder, and cellulose ethers, used as rheo-modifiers. The samples' setting properties were investigated, and printing parameters were properly adjusted. The most promising formulations were then 3D printed and calcined to obtain forsterite bioceramics, which were further characterized using confocal Raman microscopy, scanning electron microscopy, atomic force microscopy, gas porosimetry, and compressive strength tests. Our results revealed that the cellulose derivatives influence the printability of the MgO/SiO2 formulations without affecting the hardening time, which can be adjusted by the addition of sodium phosphate. The use of fine-tuned formulations allowed for the preparation of 3D-printed forsterite bioceramics, potentially suitable for biological applications as cancellous bone scaffolds. [ABSTRACT FROM AUTHOR]

The inherently huge volume expansion during Li uptake has hindered the use of Si‐based anodes in high‐energy lithium‐ion batteries. While some pore‐forming and nano‐architecting strategies show promises to effectively buffer the volume change, other parameters essential for practical electrode fabrication, such as compaction density, are often compromised. Here we propose a new in situ Mg doping strategy to form closed‐nanopore structure into a micron‐sized SiOx particle at a high bulk density. The doped Mg atoms promote the segregation of O, so that high‐density magnesium silicates form to generate closed nanopores. By altering the mass content of Mg dopant, the average radii (ranged from 5.4 to 9.7 nm) and porosities (ranged from 1.4 % to 15.9 %) of the closed pores are precisely adjustable, which accounts for volume expansion of SiOx from 77.8 % to 22.2 % at the minimum. Benefited from the small volume variation, the Mg‐doped micron‐SiOx anode demonstrates improved Li storage performance towards realization of a 700‐(dis)charge‐cycle, 11‐Ah‐pouch‐type cell at a capacity retention of >80 %. This work offers insights into reasonable design of the internal structure of micron‐sized SiOx and other materials that undergo conversion or alloying reactions with drastic volume change, to enable high‐energy batteries with stable electrochemistry. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, two flower-like magnesium silicate nanomaterials were prepared. These and another two commercial magnesium silicate materials were characterized using a scanning electron microscope, the N2 adsorption–desorption method, and other methods. The structure–activity relationship between the adsorption performance of these four magnesium silicate materials and their specific surface area, pore size distribution, and pore structure was compared. The results showed that the 3-FMS modified by sodium dodecyl sulfonate (SDS) had the largest specific surface area and pore size, the best adsorption performance, and the largest experimental equilibrium adsorption capacity (qe,exp) for Co2+, reaching 190.01 mg/g, and Cr3+, reaching 208.89 mg/g. The adsorption behavior of the four materials for Co2+ and Cr3+ both fitted the pseudo-second-order kinetic model and Langmuir adsorption model, indicating that chemical monolayer uniform adsorption was the dominant adsorption process. Among them, the theoretical adsorption capacity (qm) of 3-FMS was the highest, reaching 207.62 mg/g for Co2+ and 230.85 mg/g for Cr3+. Through further research, it was found that the four materials mainly removed Co2+ and Cr3+ through electrostatic adsorption, surface metal ions (Mg2+), and acidic groups (-OH and -SO3H) exchanging with ions in solution. The adsorption performance of two self-made flower-like magnesium silicate materials for Co2+ and Cr3+ was superior to that of two commercial magnesium silicates. [ABSTRACT FROM AUTHOR]

Oral tablets containing solubilized drug in the presence of appropriate excipients may give us an immediate release of the drug. Phospholipid solid dispersion (PSD) is a branch of solid dispersion in which phospholipid acts as a hydrophilic polymer in the presence of a suitable adsorbent to enhance the solubility of poorly soluble drugs. The anti-hyperlipidemic drug Atorvastatin (ATR) is an example of such drug, as it belongs to the class II group according to the biopharmaceutical classification system (BCS) with low bioavailability due to its low solubility. Phosphatidylcholine in combination with magnesium aluminum silicate as an adsorbent in a ratio of ATR: PC: MAS 1:3:4 was used to prepare ATR PSD by the solvent evaporation method, the product showed acceptable physical properties and utilized for the preparation of immediate-release tablets (IRTs) of ATR. Ten formulas of ATR-IRTs were prepared by direct compression method using different types and concentrations of diluents (Avicel®PH102, Avicel®PH101, and starch) and superdisintegrants (crospovidone, croscarmellose sodium, and sodium starch glycolate) and evaluated for their drug content, weight variation, hardness, friability, in vitro disintegration time and dissolution profile. The tablets formula (T10) that were prepared with ATR-PSD and Avicel®PH102 as a diluent and Croscarmellose Sodium (CCS) 5% w/w as super disintegrant show the shortest disintegration time (DT) (38 ±1 sec.) and best drug release (91% within 15 min) in 0.05M phosphate buffer (pH 6.8). [ABSTRACT FROM AUTHOR]

The balance between porosity and compressive strength, as well as the pro-osteogenic and pro-angiogenesis effects of β-tricalcium phosphate (β-TCP) are not satisfactory in the clinical application even though it has good biocompatibility, osseointegration and osteoconductivity. Herein, different contents (10, 20 and 30 wt%) of magnesium silicate (Mg 2 SiO 4, MS) and β-TCP composite bioceramic scaffolds (MS/β-TCP) were fabricated by three-dimensional fiber deposition (3DF) technology. The physicochemical, in vitro osteogenic and angiogenic properties, the early (6 weeks) cranium defect repair effects in rats and the underlying molecular mechanism on accelerating osteogenic differentiation of MS/β-TCP were systematically investigated. The results showed that MS compounding not only promoted the sintering of β-TCP and significantly enhanced the compressive strength, but also greatly improved its osteogenic and angiogenic performances, such as the viability, adhesion, and proliferation of mouse bone marrow mesenchymal stem cells (mBMSCs) and human umbilical vein endothelial cells (HUVECs), ALP activity and the expression of adhesion-related, osteogenesis-related and angiogenesis-related genes. The in vivo experiments presented that 10MS/β-TCP had more new bone formation and better angiogenesis compared to β-TCP and Blank. Analysis of the transcriptome sequencing results confirmed that the Wnt signaling pathway was involved in the regulation of osteogenic differentiation in mBMSCs by the MS/β-TCP composite bioceramic scaffold. The MS/β-TCP holds great potential in bone repair and regeneration. [ABSTRACT FROM AUTHOR]

In order to explore a wider range and lower cost of raw materials for the preparation of magnesium silicate hydrate (M-S-H), an acid-leaching method was employed to extract and separate high-purity magnesium hydroxide (Mg(OH)2) with a purity higher than 97% and amorphous silica with a purity higher than 90% from four types of natural silicate minerals (serpentine, peridotite, zeolite, and montmorillonite). These two intermediate products, which are amorphous silica and magnesium hydroxide, were used to prepare M-S-H, and the influence of curing at two temperatures, 50 °C and 80 °C, on the properties of M-S-H was investigated. The results showed that with the increase in curing temperature, the bound water content, tetrahedral polymerization degree, and Mg(OH)2 content increased. There was a good correlation between the increase in strength and the bound water content of M-S-H. This work provides a possible technological route for expanding the raw materials for preparing magnesium silicate hydrate cementitious materials and utilizing the abundant magnesium silicate minerals in the Earth's crust. [ABSTRACT FROM AUTHOR]

Magnesium oxide is one of many important materials that comprise the mantles of terrestrial planets. In this regard, its properties at high temperatures and pressures reflect the nature of the planetary interior. Shock wave loading of magnesium oxide with account for polymorphic phase transition in a pressure range of 325–400 GPa is numerically simulated using a thermodynamic equilibrium model. The parameters of the consistent equation of state for high- and low-pressure magnesium oxide phases (MgO I and MgO II) are determined. The thermodynamic parameters of these phases are simulated. The Hugoniots of single and double compression are constructed in a range of 1–1000 GPa, and the following parameters are calculated: heat capacity along the normal isobar, entropy as a function of temperature, and temperature along the Hugoniot. The simulation results are verified using data from experiments and calculations of other authors. [ABSTRACT FROM AUTHOR]

Natural Mg phyllosilicates are potential sources of divalent cations, which are necessary for the mineralization of CO2 into carbonates. The influence of inorganic () and organic (oxalate and citrate) ligands on the dissolution kinetics of talc and serpentine was studied in experiments in a flow-through reactor at 25°C. The dissolution rates of natural silicates r (mol cm–2 s–1) in solutions of various composition were calculated at the stationary stage of dissolution after a rapid initial stage, which is characterized by the formation of a surface leached layer depleted in magnesium. The presence of ligands increases the dissolution rate of magnesium silicates due to the formation of surface complexes, which leads to magnesium separation from the surface and transfer into solution. The initial incongruent stage may be the most promising for the development of carbonation technologies, because the minimum removal of the network-forming elements prevents the undesirable formation of secondary minerals (for example, clays), which exclude divalent cations from the carbonation process and greatly reduce the permeability of rocks. [ABSTRACT FROM AUTHOR]

To address the problem of insufficient temperature and salt resistance of existing polymer viscosity enhancers, we designed an organic–inorganic hybrid composite as a viscosity enhancer for water-based drilling fluids, named LAZ, and it was prepared by combining a water-soluble monomer and lithium magnesium silicate (LMS) using an intercalation polymerization method. The composite LAZ was characterized using Fourier transform infrared spectroscopy, transformed target X-ray diffractometry, scanning electron microscopy, and thermogravimetric analysis. The rheological properties of the composite LAZ were evaluated. The composite LAZ was used as a water-based drilling fluid viscosity enhancer, and the temperature and salt resistance of the drilling fluid were evaluated. The results showed that the composite LAZ presented a complex reticulation structure in an aqueous solution. This reticulation structure intertwined with each other exhibited viscosity-enhancing properties, which can enhance the suspension properties of water-based drilling fluids. The aqueous solution of the composite LAZ has shear dilution properties. As shear rate increases, shear stress becomes larger. The yield stress value of the aqueous solution increases as the composite LAZ's concentration increases. The aqueous solution of the composite LAZ exhibits strong elastic characteristics with weak gel properties. The addition of the composite LAZ to 4% sodium bentonite-based slurry significantly increased the apparent viscosity and dynamic shear of the drilling fluid. The drilling fluids containing the composite LAZ had good temperature resistance at 150 °C and below. The rheological properties of brine drilling fluids containing the composite LAZ changed slightly before and after high-temperature aging at 150 °C. [ABSTRACT FROM AUTHOR]

In food safety implementation, bacterial inactivation is an imperative aspect of hygiene and sanitation. Studies on lithium magnesium silicate (LMS) hydrosol incorporated with slightly acidic electrolyzed water (SAEW) for decontamination of pathogenic bacteria are limited. This present study aimed to investigate the bactericidal efficacy of LMS hydrosol incorporated with SAEW against Escherichia coli. Optimum combination conditions of SAEW, hydrosol concentration, and available chlorine concentration (ACC) were optimized by response surface methodology under the central composite design against the growth of E. coli. The optimum combination conditions of exposure time, hydrosol concentration, and ACC were 9.5 minutes, 1.7%, and 20.5 ppm, respectively. The results showed that the increase in ACC led to inactivation in the survival of E. coli compared with the control (p<0.05). It can be concluded that the best combination percentage between SAEW and hydrosol ranged from 1.5-1.7%, in which E. coli was reduced by 4.50 log10 CFU/mL at an ACC of 9.94 ppm. When increasing the ACC to 14.84 ppm, E. coli was reduced by 4.51 log10 CFU/mL compared with the initial number of bacteria (8.20 log10 CFU/mL) in the control group. The number of bacteria was undetected after increasing ACC to 19.93, 25.15, and 29.88 ppm at 10 min. This study suggests that LMS hydrosol incorporated with SAEW could potentially be used as an effective sanitizer. [ABSTRACT FROM AUTHOR]

The Strytan Hydrothermal Field (SHF) in basaltic terrain in Iceland is one of the extant alkaline submarine hydrothermal vent systems favoured as analogues for where life on Earth may have begun. To test this hypothesis we analyse the composition, structure, and mineralogy of samples from hydrothermal chimneys generated at the SHF. We find that the chimney precipitates are composed of Mg-silicates including clays of the saponite-stevensite group (high Mg and Si, low Fe and Al), Ca-carbonates and Ca-sulfates. The chimneys comprise permeable structures with pores sizes down to 1 µm or less. Their complex interiors as observed with SEM (Scanning Electron Microscopy) and X-ray CT (computed tomography scanning), exhibit high internal surface areas. EDX (energy-dispersive X-ray spectroscopy) analysis reveals an increase in the Mg/Si ratio toward the chimney exteriors. Chemical garden analogue experiments produce similar Mg–silicate chimneys with porous internal structures, indicating that injection-precipitation experiments can be high-fidelity analogues for natural hydrothermal chimneys at the SHF. We conclude that SHF chimneys could have facilitated prebiotic reactions comparable to those proposed for clays and silica gels at putative Hadean to Eoarchean alkaline vents. Analysis of the fluid dynamics shows that these chimneys are intermediate in growth rate compared to faster black smokers though slower than those at Lost City. The SHF is proposed as a prebiotic alkaline vent analogue for basaltic terrains on the early Earth. [ABSTRACT FROM AUTHOR]

Bioceramics provide promising tactics for wound healing, yet the on‐shelf products are still unmet, especially for skin appendages regeneration. Herein, the inorganic magnesium silicate sprays (MSS) as mineral factors to overcome the existing challenges is proposed. Results indicate MSS can be synthesized by a green method without organic solvents, templates, calcination, and harmful by‐products. With amorphous phase, nanoscale, and high specific surface area, MSS reveal an improved pH‐responsive degradability and excellent bioactivity for cell proliferation and migration. In rats, MSS display a dose‐dependent effect on accelerating burn‐wound repair via regulating the expressions of iNOS and IL‐10 to attenuate inflammation, elevating the expressions of CD31 and α‐SMA to improve vascularization, and boosting collagen deposition without ectopic calcification. The released Mg and Si ions synergistically potentiate the expressions of Gap43, Tubb3, and K19, suggesting the regeneration of peripheral nerves and hair follicles. These superior features are further verified by comparisons with commercial products, Dermlin® and 45S5 bioglass®, in both rats and minipigs. Motivated by these findings, three MSS‐based formulations of band‐aid patch, adhesive hydrogel, and antibacterial sprays are devised for specific scenarios. Taken together, this proof‐of concept study provides a promising bioactive mineral for future clinical skin wound repair and functional appendages regeneration. [ABSTRACT FROM AUTHOR]

The results of modeling the shock-wave loading of Mg2SiO4 forsterite, which in this case is considered as a mixture of SiO2 quartz and MgO periclase, are presented. The model is based on the assumption that the components of the mixture under shock-wave loading are in thermodynamic equilibrium. The model allows us to reliably describe the phase transition region. The components of the investigated material are considered as a mixture of low and high pressure phases. Polymorphic phase transitions of quartz and periclase are taken into account in the calculation of forsterite in pressure range from 1 to 1000 GPa. The results are verified by experimental data obtained in dynamic experiments. [ABSTRACT FROM AUTHOR]

Layered magnesium silicate was modified by water-insoluble chlorin e6 derivatives with two and three ethanolamine fragments on the periphery of the macrocycle by introducing chlorin e6 derivatives into the reaction medium as solutions in hydrochloric acid without the use of organic solvents. The modified layered silicates obtained are characterized by intense fluorescence along with photostability and exhibit photochemical activity in reactions of photosensitized oxidation of model pollutants like xanthene (rhodamine 6G) and azo dyes (methyl orange). [ABSTRACT FROM AUTHOR]

The use of rock dust in agriculture has increased worldwide and particularly in Brazil since its regulation by Law 12.890 (2013). However, some inconsistent results in standard chemical analysis of soils amended with rock dust have drawn attention, and among them, cation exchange capacity (CEC). This paper evaluates the increase in sum of bases (SB) and CEC of two soils amended with commercial rock dust (magnesium silicate), measured by four methods: ion exchange resin, potassium chloride (KCl), compulsive exchange and cesium adsorption. The maximum possible increase of SB in the soil was estimated based on the total chemical analysis of the rock dust and compared to the measured CEC results. We concluded the resin method inflated the results, due to the dissolution of rock dust particles by the acid extraction used to recover the adsorbed cations in resin beads. These extra cations caused overestimation of the sum of bases and consequently, of the estimated CEC. Among the methods used, direct CEC methods were more appropriate, as well as the KCl, since it does not employ acid extractions at any step. In addition, calculations based on the total chemical analysis of the rock dust can help to identify some of the cases in which the routine analysis is inflated by the dissolution of rock dust. [ABSTRACT FROM AUTHOR]

Environmental context: Mine tailings are a mixture of fine materials obtained after crushing, processing and extracting the valuable minerals from ore. Ultramafic and mafic mine tailings have the potential to mineralise carbon, offering a solution to offset greenhouse gas emissions from the mining sector. The study revealed that the effects of wetting and drying ultramafic and mafic mine tailings under atmospheric conditions have the potential for carbon sequestration and acid mine drainage. Rationale: As the result of their carbon mineralisation potential, there is an increasing interest in using ultramafic and mafic (U+M) mine tailings as a feedstock for carbon (C) sequestration. However, little is known about the relative chemical stability of U+M minerals, and it is unclear whether acid mine drainage may be generated during weathering. Methodology: This study determined the relative stability of the constituent minerals of several U+M tailings from mines in British Columbia, Canada, and Australia using selective chemical extractions and an 18-week laboratory experiment of cycles of wetting and drying to simulate conditions that may be experienced under field conditions. Tailings were mixed with topsoil to investigate the potential use as a soil amendment. Results: Initially, the tailing sample's pH was 8.4–9.7 and decreased to 7.7–9.1 over the 18 weeks. Soil additions lowered the initial pH and converged with the tailing's pH over 18 weeks. Sequentially weathered minerals determined by X-ray diffraction were consistent with the empirical Goldich weathering sequence. Metal concentrations from inductively coupled plasma–mass spectrometry supported X-ray diffraction results, confirming the stability of the U+M tailings using different methods and the need for future studies on potential metal contamination. Discussion: Minor concentrations of sulfur seemed to have resulted in larger fluctuations in pH when low amounts of carbonates were present. However, reactive oxides and basic cations in the U+M tailings maintained pH above 7. Therefore, C sequestration was likely supported, although there was a slight reduction in total C content for almost all samples. This study suggests future research is required under field conditions to confirm C sequestration and to investigate the use of U+M tailings for restoration applications. Environmental context. Mine tailings are a mixture of fine materials obtained after crushing, processing and extracting the valuable minerals from ore. Ultramafic and mafic mine tailings have the potential to mineralise carbon, offering a solution to offset greenhouse gas emissions from the mining sector. The study revealed that the effects of wetting and drying ultramafic and mafic mine tailings under atmospheric conditions have the potential for carbon sequestration and acid mine drainage. [ABSTRACT FROM AUTHOR]

Reconstruction of irregular oral-maxillofacial bone defects with an inflammatory microenvironment remains a challenge, as chronic local inflammation can largely impair bone healing. Here, we used magnesium silicate nanospheres (MSNs) to load microRNA-146a-5p (miR-146a) to fabricate a nanobiomaterial, MSN+miR-146a, which showed synergistic promoting effects on the osteogenic differentiation of human dental pulp stem cells (hDPSCs). In addition, miR-146a exhibited an anti-inflammatory effect on mouse bone marrow-derived macrophages (BMMs) under lipopolysaccharide (LPS) stimulation by inhibiting the NF-κB pathway via targeting tumor necrosis factor receptor-associated factor 6 (TRAF6), and MSNs could simultaneously promote M2 polarization of BMMs. MiR-146a was also found to inhibit osteoclast formation. Finally, the dual osteogenic-promoting and immunoregulatory effects of MSN+miR-146a were further validated in a stimulated infected mouse mandibular bone defect model via delivery by a photocuring hydrogel. Collectively, the MSN+miR-146a complex revealed good potential in treating inflammatory irregular oral-maxillofacial bone defects. [ABSTRACT FROM AUTHOR]

This study conducts low-vacuum sulfidation to form a sulfidation layer on the serpentinite-derived magnesium iron silicate, thereby enhancing its electrochemical properties. Results show (Mg,Fe)2SiO4 calcined at 900 °C has the best crystallinity, and the cubic FeS2 is synthesized on the surface of the orthorhombic magnesium iron silicate (MFS). Two distinct charge plateaus can be distinguished during the first charge process, and the discharge capacities increased significantly. This study confirms that the surface FeS2 layer provides extra ion pathways, allowing more lithium/magnesium ions to be extracted and inserted in the serpentinite-derived magnesium iron silicate. Accordingly, the serpentinite electrode boasts straightforward exploitation with low-cost advantages and potential. [ABSTRACT FROM AUTHOR]

Anhydrous phase B (anh‐B) is a dense magnesium silicate with the composition Mg14Si5O24 and space group Pmcb. In magnesium‐rich environments, forsterite reacts with periclase to form anh‐B, and the formation of anh‐B was proposed as a plausible mechanism for the origin of the X‐discontinuity. However, the elastic properties of anh‐B, which are critical for evaluating the seismic features associated with its formation, have not been determined. In this study, we investigated the elasticity of anh‐B at high pressure and temperature via first‐principles calculations. Combining with the elasticity of other minerals, we determined the contrasts caused by the formation of anh‐B: ∼3%, ∼7%, and ∼10% jumps for density, VP, and VS, respectively. The 2%–8% impedance contrasts of the X‐discontinuity can be explained by the formation of 15–60 vol% anh‐B, which requires 3–12 vol% MgO as a reactant. Plain Language Summary: The reaction between forsterite and periclase, leading to the formation of anhydrous phase B (anh‐B), has been suggested as a plausible mechanism for the X‐discontinuity. However, the exact impedance contrasts associated with this reaction remain unclear due to the previously undetermined elasticity of anh‐B. To address this knowledge gap, our study utilized first‐principles calculations to thoroughly investigate the elastic properties of anh‐B under mantle conditions. By incorporating the elasticity data of other minerals, we successfully derived the property contrasts resulting from the formation of anh‐B for the first time. Our results indicate that 15–60 vol% anh‐B needs to be formed to explain the X‐discontinuity. These insightful results significantly advance our understanding of the reaction's seismic implications. Key Points: We obtained the elasticity of anhydrous phase B under mantle conditions for the first time via first‐principles calculationsThe formation of anhydrous phase B causes ∼10% P‐wave impedance contrast and ∼13% S‐wave impedance contrastThe formation of 15–60 vol% anhydrous phase B can explain the deep X‐discontinuity in the cold subduction zones [ABSTRACT FROM AUTHOR]

To limit global temperature rise to below 2°C, we need to radically and rapidly change the way we build and use materials, since construction is responsible for 20‐40% of industrial CO2 emissions. Magnesium carbonate‐based cements have the potential to become a major carbon sink in construction industry, as CO2 will not be emitted during their production, but CO2 will rather be bound during hardening. Two different reaction mechanisms lead to setting and hardening of such HMC cements: i) hydration of MgO‐Mg‐carbonate, also in blends with silica and other mineral additions, in the presence of water or salt solutions (such as sodium bicarbonate solution) at ambient conditions or ii) carbonation hardening of MgO‐based systems at increased CO2 partial pressure and/or at increased temperatures. However, the utilization of hydrated magnesium carbonate and magnesium silicate cements is currently hampered by the lack of systematic experiments and of fundamental understanding of the factors affecting the hardening process, mechanical properties, long‐term behavior and durability. In particular, the role of temperature, relative humidity and addition of supplementary cementitious materials and/or industrial by‐products has not been systematically investigated. We need knowledge both on the practical side through systematic experiments with pastes, mortars and concretes as well as on a fundamental level through solubility and sorption experiments and thermodynamic modelling. In addition, reaction kinetics need to be optimized as well as the early formation of the preferred phases (stability enhancement) to develop efficient HMC cements for construction. Due to the socio‐economic relevance of cement and concrete, the impact of such "carbon"‐negative cements may go beyond a purely scientific one and lead to technological breakthroughs to the benefit of environment and society. [ABSTRACT FROM AUTHOR]

Binders based on blends of reactive magnesia and hydromagnesite are low‐CO2 or even carbon‐negative cements in case the MgO is generated from magnesium silicates or Mg‐containing brines. When MgO is hydrated with water alone, a well crystalline brucite forms, but no measurable strength is developing. In the presence of hydromagnesite, the hydration of MgO is accelerated and the hydrate assemblage is changed. A poorly‐crystalline brucite containing some carbonate is the main hydration product. Furthermore, a kind of "gel‐water" is observed, which is lost at temperatures above 40‐60°C. This brucite‐like phase is responsible for strength formation in MgO‐hydromagnesite blends. After 28 days, a mortar compressive strength is reached similar to the one of a Portland cement of strength class 32.5. [ABSTRACT FROM AUTHOR]

Today, hydroxyapatite (HA)-based composite scaffolds are widely studied, but there is a lack of a doping method that can simultaneously improve the mechanical strength, degradation rate, and bioactivity of HA scaffolds. In this paper, the amorphous magnesium silicate (MS) with a low melting point is selected as the doping phase of HA. The hydroxyapatite/magnesium silicate composite was fabricated using photocuring technology. In addition, at high temperatures, ionic substitution can occur between the magnesium silicate glass phase and the HA lattice. Therefore, a new phase with a pinning effect can be obtained at the grain boundary and the magnesium silicate can further improve the biocompatibility of HA scaffolds. In the sintering process, the magnesium silicate was melted to a liquid state, and then the sintering temperature of the scaffold was reduced for grain refinement. The morphological analysis shows that MS doping is an important factor for grain refinement, which has been reduced from 12 μm to 6 μm. Furthermore, the formation of new diopside and whitlockite phases with a pinning effect has been observed at the grain boundaries. Specifically, the compressive stress of the composite scaffold is increased by 59.15% compared to the pure HA scaffold. However, the soaking and cell experimental findings show that the composite scaffold has a better degradation rate, cell activity, and bone induction. Finally, this study found that a composite scaffold with improved mechanical strength, degradation performance, and biocompatibility can be obtained with the addition of magnesium silicate as the doping phase of HA with 30 wt% of. [ABSTRACT FROM AUTHOR]

Magnesium silicates combining acidic and basic surface properties are known to be interesting as heterogeneous catalysts. Nevertheless, their catalytic performances are highly dependent on the synthesis method used. In this study, a series of magnesium silicates was synthesized for the first time using a coprecipitation method with a micromixer. It is first shown that changes in synthesis/precipitation pH led to magnesium silicates with different Mg/Si ratios: the higher the synthesis pH, the higher the Mg/Si ratio. Moreover, prepared silicates with a final Mg/Si ratio greater than 0.7, thus prepared at high pH, exhibit negligible specific surface area, whereas relatively high values (>180 m2/g) have been obtained for lower Mg/Si ratios. A set of experimental characterization data obtained by N2 physisorption, SEM, XRD, TGA-DTA as well as Raman and 29Si NMR spectroscopies are presented and discussed. They show the existence of two distinct families with a similar Magnesium Silicate Hydrate (MSH) phase, but they reveal different aggregation states and textural properties. Finally, the surface acid–base reactivity of the co-precipitated magnesium silicates was determined using the model reaction of 2-methylbut-3-yn-2-ol (MBOH) conversion. The results obtained suggest that it is possible to prepare silicates with a wide range of surface acid–base properties, from purely basic solids to those with both acidic and basic properties, by adjusting the final Mg/Si ratio via the control of the synthesis parameters. [ABSTRACT FROM AUTHOR]

This paper presents the results of an investigation of Zn–Mg(Zr)Si nanophase oxide systems modified with rare-earth elements (REE: yttrium, lanthanum, and cerium). The prepared systems are characterized by X-ray diffraction, low-temperature (77 K) nitrogen ad(de)sorption, Raman, UV–Vis diffuse reflectance and FTIR spectroscopy of adsorbed pyridine, and temperature-programmed desorption of NH3 and CO2. The effect of REE modification on the efficiency of the aqueous ethanol-to-1,3-butadiene process over Zn–Mg(Zr)Si oxide catalysts is shown. The rate of 1,3-butadiene formation rises up to four times as a result of the acceleration of the key step of the ethanol-to-1,3-butadiene process, the aldol condensation of acetaldehyde. The cause of this effect is a change in acid–base characteristics of Zn–Mg(Zr)Si oxide systems upon the introduction of REE additives in their composition. The change in acid–base characteristics of the modified Zn–MgSi oxide system is additionally caused by the formation of a nanolayered magnesium silicate hydrate phase. [ABSTRACT FROM AUTHOR]

Magnesium silicate hydrate (MSH) cement has the advantages of low energy consumption, minimal environmental pollution, carbon negativity, and reduced alkalinity, but excessive drying shrinkage inhibits its application. This paper analyzed the influence of steel slag (SS) dosage, carbon dioxide partial pressure, and carbonation curing time on the compressive strength, shrinkage rate, and phase composition of MSH cement. Various analysis methods, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP), were used to study the hydration products and microstructure. The results showed that under normal curing conditions, MSH cement mixed with different steel slag contents experienced a decline in strength at all ages. However, the greater the amount of SS incorporated, the lesser the degree of drying shrinkage. The compressive strength of all groups was improved, and the drying shrinkage was reduced by carbonation treatment. The samples with 5%, 10%, and 15% SS content exhibited shrinkage rates of 2.19%, 1.74%, and 1.60%, respectively, after 28 days of curing. The reason was that after carbonation treatment, hydrated magnesium carbonates (HMCs) were generated in the SS–MSH cement, and a Ca–Mg–C amorphous substance formed by hydration and carbonation of C2S in steel slag filled in the pores, which enhanced the density of the matrix, improved the compressive strength of the specimen, and reduced the shrinkage rate. [ABSTRACT FROM AUTHOR]

The magnesium silicate hydrate system (MgO-SiO2-H2O) possesses issues such as susceptibility to cracking, brittleness, and poor volumetric stability, which hinder its development and practical use in engineering applications. This study aimed to enhance the properties of the MgO-SiO2-H2O system by incorporating glass fiber as a reinforcing material. The mechanical properties, shrinkage properties, and properties during accelerated aging were tested at different content levels of glass fiber. Additionally, the reaction mechanism and microscopic morphology were characterized using microscopic testing methods. The results revealed that the addition of glass fiber improved the mechanical properties of the MgO-SiO2-H2O system; meanwhile, with an increase in fiber content, the mechanical properties showed an initial increase followed by a decreasing trend. With a glass fiber content of 0.6%, the system exhibited a flexural strength of 7.9 MPa at 28 d, a compressive strength of 42.5 MPa at 28 d, and a 27.2% increase in splitting tensile strength compared to the control group. At a fiber content of 0.9%, the flexural toughness steadily increased, reaching a maximum value of 2.238 N·m, which is 5.41 times greater than that of the control group. Moreover, the incorporation of glass fiber effectively inhibited the shrinkage of the MgO-SiO2-H2O system. Accelerated aging experiments confirmed that the glass fiber in the MgO-SiO2-H2O system did not undergo significant deterioration or corrosion, thereby maintaining long-term stability. These findings have important theoretical and practical significance for the application and development of the MgO-SiO2-H2O system. [ABSTRACT FROM AUTHOR]

Viscous healing of cracks induced by the Vickers indentation in a soda lime magnesium silicate, a soda borosilicate, and a soda aluminosilicate glass (NAS) was studied by laser scanning microscopy. Plots of the crack length, width, and depth normalized to the initial crack length versus time over viscosity merge into single master curves of each of these quantities for each glass. Despite glass properties do not differ strikingly from each other, however, these master curves strongly differ among the glasses. This finding was attributed to a different interplay of various crack healing phenomena. Lateral cracks were found to be responsible for the bulging of the sample surface around the Vickers imprint, which in turn promotes radial crack widening as the main cause of healing delay. The most rapid healing of lateral cracks was observed in NAS in which bulging and crack widening were least pronounced. [ABSTRACT FROM AUTHOR]

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For the investigation of the reactivity of alternative solid oxide cell air electrode materials with forsterite (Mg2SiO4), a magnesium silicate doped with Zn and Ca, five different phase materials were chosen: two Ruddlesden–Popper phase materials: La4Ni3O10 (L4N3) and La3Ni2O7 (L3N2) and three titanium-based perovskite materials: SrTiO3 (STO), SrTi0.75Fe0.25O3 (STF25) and CaTi0.9Fe0.1O3 (CTF). Forsterite was chosen as a support material for the fuel cell, as it is abundant and therefore relatively inexpensive. For the investigation of their reactivity, different types of samples were prepared: mixed pellets, double-layered pellets and screen-printed electrode inks on forsterite green substrates, which were subsequently co-sintered at T = 1300 °C. These samples and their cross sections were then studied using XRD, SEM, EDS and TEM lamella point analysis. Consequently, the impedance spectra were acquired to determine their electro-catalytic performance. The two Ruddlesden–Popper phase materials L4N3 and L3N2 are of high interest due to their thermodynamic stability and high electro-catalytic activity, resulting in a very low polarization resistance. However, this polarization resistance is increased when mixing with forsterite material. In case of the three titanium-based perovskites, the electro-catalytic activity is of less interest due to high polarization resistances. [ABSTRACT FROM AUTHOR]

A novel controllable magnesium silicate nanotube (MSN) material derived from coal fly ash was successfully synthesized via a hydrothermal process for the first time, and the reaction conditions and mechanism of synthesizing MSN materials from magnesium oxide and sodium silicate extracted from the fly ash were studied. The optimal preparation conditions are temperature = 220 °C, pH = 13.5, and Mg: Si molar ratio = 3:2, and the tubular structure gradually appeared and showed controllable and regular growth with the increase of synthesis time. The mechanism revealed that with the gradual dissolution of brucite into the sodium silicate solution, the reaction product begins to crystallize and transform from an initial sheet-like structure to a tubular structure, and finally becomes a uniformly arranged nanotube. The formation process of MSN follows Pauling's fourth rule, Si–O tetrahedral coordination and Mg–OH octahedral coordination is further condensed to form a two-layer structure by the action of active oxygen, then the sheet is rolled into a tube under its structural stress. The growth of both outer tubular diameter and inner tubular diameter has good linear law and controllable, and the growth rate are 0.289 nm h−1 and 0.071 nm h−1, respectively. [ABSTRACT FROM AUTHOR]

The effect of partial SiO2 substitution with Al2O3 and B2O3 on the thermal properties and crystallization of glass sealants in the (50 − x)SiO2–30BaO–20MgO–xAl2O3(B2O3) (wt %) system is studied. It is established that the coefficient of thermal expansion of all obtained glasses lies within a range of 8.2–9.9 × 10−6 K−1. Alumina-doped glasses crystallize after quenching, while samples containing boron oxide are completely amorphous. Magnesium silicates are formed in all glasses after exposure at 1000 °C for 125 h. After 500 h of exposure, a noticeable diffusion of zirconium ions is observed from the YSZ electrolyte to the glass sealant volume, resulting in the formation of the BaZrSi3O9 compound. The crystallization and products of interaction between YSZ ceramics and boron-containing sealants have no significant effects on the adhesion and properties of glass sealants, which makes them promising for applications in electrochemical devices. [ABSTRACT FROM AUTHOR]