Explore the vast range of titles available.

Magnesium phosphate (MgP) has garnered growing interest in hard tissue replacement processes due to having similar biological characteristics to calcium phosphate (CaP). In this study, an MgP coating with the newberyite (MgHPO4·3H2O) was prepared on the surface of pure titanium (Ti) using the phosphate chemical conversion (PCC) method. The influence of reaction temperature on the phase composition, microstructure, and properties of coatings was systematically researched with the use of an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a laser scanning confocal microscope (LSCM), a contact angle goniometer, and a tensile testing machine. The formation mechanism of MgP coating on Ti was also explored. In addition, the corrosion resistance of the coatings on Ti was researched by assessing the electrochemical behavior in 0.9% NaCl solution using an electrochemical workstation. The results showed that temperature did not obviously affect the phase composition of the MgP coatings, but affected the growth and nucleation of newberyite crystals. In addition, an increase in reaction temperature had a great impact on properties including surface roughness, thickness, bonding strength, and corrosion resistance. Higher reaction temperatures resulted in more continuous MgP, larger grain size, higher density, and better corrosion resistance.

Magnesium potassium phosphate cement (MKPC) is formed on the basis of acid–base reaction between dead burnt MgO and KH2PO4 in aqueous solution with K-struvite as the main cementitious phase. Due to the unique characteristics of these cements, they are suitable for special applications, especially the immobilization of radioactive metal cations and road repair projects at low temperature. However, there are few articles about the hydration mechanism of MKPC. In this study, the types, proportions and formation mechanism of MKPC crystalline phases under different magnesium to phosphorus (Mg/P) ratios were studied by means of AAS, ICP-OES, SEM, EDS and XRD refinement methods. Corresponding MD simulation works were used to explain the hydration mechanism. This study highlights the fact that crystalline phases distribution of MKPC could be adjusted and controlled by different Mg/P ratios for the design of the MKPC, and the key factor is the kinetic of K+.

The new mineral manganonewberyite (IMA2024-004), Mn(PO3OH)(H2O)3, was found underground at the Cassagna mine, Liguria, Italy, where it is a secondary phase formed by the interaction of bat guano with Mn-rich rock. Manganonewberyite occurs with niahite, kutnohorite, sampleite and serrabrancaite on a tinzenite-quartz-braunite matrix. Crystals are prisms and blades, up to ∼0.15 mm long, elongated parallel to [001], flattened on {100} and exhibiting the forms {100}, {010} and {111}. Crystals are colourless and transparent, with vitreous lustre and white streak. The mineral is brittle with curved fracture. The Mohs hardness is ∼3. Cleavage is perfect on {010}. The density is 2.34(2) g·cm-3. Optically, manganonewberyite is biaxial (+) with α = 1.541(2), β = 1.547(2) and γ = 1.559(2) (white light). The 2V is 71.6(3)°. The optical orientation is X = a, Y = b and Z = c. The empirical formula is (Mn0.960Mg0.016Ca0.015)Σ0.991(H1.02P1.00O4)(H2O)3. Manganonewberyite is orthorhombic, space group Pbca, with cell parameters: a = 10.4273(6), b = 10.8755(8), c = 10.2126(4) Å, V = 1158.13(11) Å3 and Z = 8. The crystal structure (R1 = 2.79% for 892 I > 2σI reflections) is the same as that of newberyite with Mn in place of Mg.

Struvite-K cements, also called magnesium potassium phosphate cements (MKPCs), are applicable for particular applications, especially the immobilization of radioactive Cs+ in the nuclear industry. This work focuses on how Cs+ affects the hydration mechanism of struvite-K cements because newberyite and brucite in the hydration products are deemed to be risky products that result in cracking. Experiments and molecular dynamics simulations showed that Cs+ promoted the diffusion of K+ to the surface of MgO, which greatly facilitates the formation of more K-struvite crystals, inhibiting the formation of newberyite and brucite. A total of 0.02 M Cs+ resulted in a 40.44%, 13.93%, 60.81%, and 32.18% reduction in the amount of newberyite and brucite, and the Cs immobilization rates were 99.07%, 99.84%, 99.87%, and 99.83% when the ratios of Mg/P were 1, 3, 5, and 7, respectively. This provides new evidence of stability for struvite-K cements on radioactive Cs+ immobilization. Surprisingly, another new crystal, [CsPO3·H2O]4, was found to be a dominating Cs-containing phase in Cs-immobilizing struvite-K cements, in addition to Cs-struvite.

Low-temperature ceramics based on magnesium calcium phosphate cement are a promising resorbable material for bone tissue restoration with the possibility of functionalization. The replacement of the magnesium Mg2+ ion with a calcium Ca2+ ion at the stage of preparation of the precursor leads to the production of multiphase ceramics containing phases of brushite, monetite, and newberyite, with different dissolution rates. Multiphase ceramics leads to volumetric resorption with preservation of their geometric shape, which was confirmed by the results of an evaluation of the output of magnesium Mg2+ and calcium Ca2+ ions into the contact solution of the ceramics and the X-ray density of ceramic samples during subcutaneous implantation. The combined introduction of sodium pyrophosphate decahydrate and citric acid monohydrate as setting inhibitors neutralizes their insignificant negative effect on the physico-chemical properties of ceramics (strength, pH, porosity), determining the optimal composition. In vivo experiments with setting inhibitors in the composition of ceramics showed a different biological response, affecting the rate of resorption on par with magnesium ions. Preliminary data on biocompatibility and solubility determined magnesium-calcium phosphate ceramics containing additives that regulate setting to be a potential material for bone tissue restoration and a vector for further research, including in orthotopic implantation models.

Due to the positive effects of magnesium substitution on the mechanical properties and the degradation rate of the clinically well-established calcium phosphate cements (CPCs), calcium magnesium phosphate cements (CMPCs) are increasingly being researched as bone substitutes. A post-treatment alters the materials’ physical properties and chemical composition, reinforcing the structure and modifying the degradation rate. By alkaline post-treatment with diammonium hydrogen phosphate (DAHP, (NH 4 ) 2 HPO 4 ), the precipitation product struvite is formed, while post-treatment with an acidic phosphate solution [e.g., phosphoric acid (PA, H 3 PO 4 )] results in precipitation of newberyite and brushite. However, little research has yet been conducted on newberyite as a bone substitute and PA post-treatment of CMPCs has not been described in the accessible literature so far. Therefore, in the present study, the influence of an alkaline (DAHP) or acid (PA) post-treatment on the biocompatibility, degradation behavior, and osseointegration of cylindrical scaffolds ( h = 5.1 mm, Ø = 4.2 mm) produced from the ceramic cement powder Ca 0.75 Mg 2.25 (PO 4 ) 2 by the advantageous manufacturing technique of three-dimensional (3D) powder printing was investigated in vivo . Scaffolds of the material groups Mg225d (DAHP post-treatment) and Mg225p (PA post-treatment) were implanted into the cancellous part of the lateral femoral condyles in rabbits. They were evaluated up to 24 weeks by regular clinical, X-ray, micro-computed tomographic (µCT), and histological examinations as well as scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis and compared with tricalcium phosphate (TCP). All materials showed excellent biocompatibility and rapid osseointegration. While TCP degraded only slightly, the CMPCs showed almost complete degradation. Mg225d demonstrated significantly faster loss of form and demarcability from surrounding bone, scaffold volume reduction, and significantly greater degradation on the side towards the bone marrow than to the cortex than Mg225p. Simultaneously, numerous bone trabeculae have grown into the implantation site. While these were mostly located on the side towards the cortex in Mg225d, they were more evenly distributed in Mg225p and showed almost the same structural characteristics as physiological bone after 24 weeks in Mg225p. Based on these results, the acid post-treated 3D powder-printed Mg225p is a promising degradable bone substitute that should be further investigated.

The paper is devoted to the creation and investigation of the new cement materials formed the new beryite phase (MgHPO4·3H2O) during the setting processes. A cement liquid based on sodium phosphate solution with addition of sodium hyaluronate polymer is used to increase the viscosity and the surface tension in the system and to increase the cohesion of the final product. The effect of cement liquids based on sodium hyaluronate with various concentrations are studied to estimate the phase composition, setting time, pH value, microstructure, injectivity, and strength properties of cement materials.

Intensive manure application is an important source of diffuse phosphorus (P) pollution. Phosphorus availability from animal manure is influenced by its chemical speciation. The major objective of this study was to investigate the P speciation in raw and anaerobically digested dairy manure with an emphasis on the calcium (Ca) and magnesium (Mg) phosphate phases. Influent and effluent from an on-farm digester in Wisconsin were sampled and sieved, and the 25 to 53 μm size fraction was dried for X-ray powder diffraction (XRD) and P K-edge X-ray absorption near edge structure (XANES) analyses. Struvite (MgNH4PO4·6H2O) was identified in both the raw (influent) and anaerobically digested (effluent) manure using XRD. Qualitative analysis of P K-edge XANES spectra indicated that the Ca orthophosphate phases, except dicalcium phosphate anhydrous (DCPA) or monetite (CaHPO4), were not abundant in dairy manure. Linear combination fitting (LCF) of the P standard compounds showed that 57.0 and 43.0% of P was associated with DCPA and struvite, respectively, in the raw manure. In the anaerobically digested sample, 78.2% of P was present as struvite and 21.8% of P was associated with hydroxylapatite (HAp). The P speciation shifted toward Mg orthophosphates and least soluble Ca orthophosphates following anaerobic digestion. Similarity between the aqueous orthophosphate (aq-PO4), newberyite (MgHPO4·3H2O), and struvite spectra can cause inaccurate P speciation determination when dairy manure is analyzed solely using P K-edge XANES spectroscopy; however, XANES can be used in conjunction with XRD to quantify the distribution of inorganic P species in animal manure.

The newberyite MgHPO 4 ·3H 2 O antacid activity has never been investigated before. Crystalline and heated Newberyite, at 200 °C, was tested as a neutralizing of hydrogen chloride acid (HCl 0.1 M to simulate gastric juice). Results show that the substrate has a basic behavior and may be used as an active ingredient in the antacid formulation. HCl Neutralization 0.1 M depends of newberyite concentration and pH1 was reached when 0.5 M was used. The crystalline and heated newberyite antacid power was compared with that of some commercial antacids. The newberyite heated pushed pH to 4 after 4 min when the crystalline product was brought it to 3 after 15 min. The antacid neutralizing capacity (ANC) was evaluated using direct and reverse titration methods. ANC values increased when particle sizes decreased. The heated product at 200 °C increased strongly the ANC and the maximum value reached was 13 meq/g. The kinetic study of neutralization reaction was carried out by pHmetry. The rate constants are depending of newberyite quantity and the optimal neutralization of HCl 0.1 M was obtained for 0.5 g. The resulting structural transformations have been investigated. XRD showed that the product became amorphous after heating at 200 °C. FT-IR and Raman spectroscopy agree on departure of the three crystallization water molecules, when MgHPO 4 ·3H 2 O was heated. Surface area measurement was determined by Brunauer, Emmett and Teller and indicates that the product hasn’t an important porosity. Scanning electron microscopy coupled with energy dispersive spectrometry elementary analysis was also carried out and confirmed FT-IR and Raman spectroscopy results.

Specimens from human remains exhibiting unusual preservation excavated from a seventh century stone cist burial at Towyn y Capel in Anglesey, UK, have been analysed using Raman spectroscopy with near-infrared laser excitation at 1,064 and 785 nm. Specimens of hair and bone provided evidence for severe degradation and microbial colonisation. The deposits within the stone cist showed that some microbially mediated compounds had been formed. Analysis of crystals found at the interface between the hair and the skeletal neck vertebrae revealed a mixture of newberyite and haematite, associated with decomposition products of the hair and bone. An interesting differential degradation was noted in the specimens analysed which could be related to the air-void and the presence of plant root inclusions into the stone cist. This is the first time that Raman spectroscopy has been used in the forensic archaeological evaluation of burial remains in complex and dynamic environments.