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Ceramic materials in the Na2O–CaO–P2O5 system have been produced using powder mixtures containing calcium hydrogen phosphates (monetite/brushite: CaHPO4/CaHPO4 ∙ 2H2O) and sodium salts (Na2CO3 ∙ H2O, Na4P2O7 ∙ 10H,O, and NaPO3). These salts were used as precursors to the following high-temperature phases: Сa2P2O7, Na2O, Na4P2O7, and NaPO3. The amount of the salts in the powder mixtures was such that the oxide composition of the ceramics corresponded to 10 mol % sodium oxide for each mixture in the Na2O–CaO–P2O5 system. The powder mixtures were prepared using mechanical activation in acetone, which was accompanied by monetite rehydration to brushite. X-ray diffraction characterization showed that, after firing, the phase composition of the ceramics produced from the powder mixtures thus prepared lay in the Сa2P2O7–NaCaPO4–Na2СaP2O7–Са(РО3)2 phase field. The resultant ceramic materials contain biocompatible and bioresorbable phases and can be recommended for bone implant fabrication.

Powder mixtures based on calcium hydroxyapatite (HAP) and sodium salts in the amount corresponding to 25 mol % of Na2O in the Na2O–CaO–P2O5 system were studied by isothermal exposures in the range of 600—1200°C. According to XRD data, the phase composition of the samples of HAP/Na2CO3 after calcination included HAP, β-CaNaPO4, and CaO. The phase composition of the ceramic samples from the HAP/Na2HPO4 powder mixture after calcination contained the phases of β-CaNaPO4 and Na4P2O7. The phase composition of the ceramic samples from the powder mixture of HAP/NaH2PO4 after calcination contained Ca2P2O7, Ca10Na(PO4)7, β-CaNaPO4, CaNa2P2O7, and Na4P2O7. The presence of sodium salts in the amount corresponding to 25 mol % of Na2O in the Na2O–CaO–P2O5 system provided the occurrence of liquid- phase sintering in compact preforms from the studied powder mixtures. However, the presence of the water-soluble salt Na4P2O7 in ceramic samples of HAP/Na2HPO4 and HAP/NaH2PO4 after calcination imposes a restriction on the use of such materials in contact with an aqueous medium. And the presence of CaO in the HAP/Na2CO3 samples excludes the use of such materials as bone implants.

Alginate fibers made from seaweed have some desirable properties as textile materials, but they also have two shortcomings that limit their usages: they are intolerant to salt, alkali, and detergent, and they are difficult to dye due to the electrostatic repulsion with anionic dyes. To solve the two problems in this project, a process of successive modification of alginate fibers using sodium pyrophosphate, alum, and sodium hydroxide was developed. SEM images and ion content of the modified alginate fibers showed that the fibers did not dissolve in high concentrations of sodium chloride, sodium hydroxide, or standard detergent solution and still maintained their original morphology. Also, the results of FTIR, XPS, XRD, and single-fiber strength tests indicated that the modification process enabled the alginate fibers to form a new tetrahydroxy cross-linking structure and thus improved their mechanical properties. The tetrahydroxy cross-linking structure prevented the dissolution of alginate fibers by blocking the exchange of ions between the fibers and the solution. Besides, the presence of Al3+ in the tetrahydroxy cross-linking structure modified the electrostatic repulsion between the alginate fiber and the anionic dye, resulting in high dyeing and dye fixation rates. Thus, the modified alginate fiber can be dyed directly with common dyes without dissolution, solving the above-mentioned two problems. This can enormously expand the potential usages of alginate fibers and therefore has significant academic and practical implications.

Phosphate reduction is of important industrial relevance in the manufacturing of emulsified meat products because it may give rise to a healthier product. The effect of seven different phosphate types was tested on the physicochemical and quality characteristics to select the most promising phosphate type for further cooked sausage manufacturing. Next, phosphate mass fraction was gradually reduced. Tetrasodium di- or pyrophosphate (TSPP) and sodium tripolyphosphate (STPP) increased pH, reduced structural properties, resulted in the highest emulsion stability, lowest cooking loss and had little effect on hardness. Based on the viscoelastic properties, a minimum mass fraction of 0.06% TSPP was sufficient to obtain an acceptable quality product. Rheology proved to be a very useful tool to evaluate the quality of meat products, as it gives insight in the structure of the meat product and especially the functional properties of meat proteins. Based on the obtained results, it can be concluded that the current amount of phosphate added to emulsified meat products can be significantly reduced with minimal loss of product quality.

In this study, the effect of sodium pyrophosphate (NaPP) on the separation of apatite from dolomite by flotation was systematically investigated. Flotation results revealed that NaPP could selectively depress the flotation of apatite, thus realizing the separation of apatite from dolomite. Further, the selective depression mechanism of NaPP was studied through zeta potential measurements, contact angle measurements, and X-ray photoelectron spectroscopy (XPS) analysis. The results demonstrated that the adsorption of sodium oleate (NaOL) onto apatite surface was depressed by the preferential interaction of NaPP with active Ca sites. For dolomite, while the presence of NaPP hindered the interaction of NaOL with active Ca sites, it appeared to enhance the reactivity with active Mg sites. Thus, the adsorption of NaOL onto dolomite surface was hardly influenced. In this way, the separation of apatite from dolomite was achieved.

The study examined the composition and forms of iron and aluminium oxides in benchmark soils of central southwestern Nigeria. Soils developed from distinct parent rock types, including coarse-grained granite and gneiss, fine grained biotite gneiss and schist, and the amphibolite complex which correspond to the parent rocks of the soils of Iwo (Typic Paleustults), Egbeda (Rhodic Kandiustults) and Itagunmodi (Typic Haplustults) Associations, respectively, were selected for the study. Notably, these soils collectively encompass approximately 60% of the total land area in central southwestern Nigeria. The less than 2 mm soil fractions were pre-treated with hydrogen peroxide to remove soil organic matter. Thereafter, oxides of Fe and Al were extracted using three different extractants: dithionite-citrate-bicarbonate (DCB) mixtures, acidified ammonium oxalate and sodium pyrophosphate solution. The quantification of Fe and Al oxides contents in the respective extracts were carried out using Inductively Coupled Plasma—Atomic Emission Spectrometry. The research findings indicated that the DCB extractable forms of Fe and Al oxides were more abundant compared to other forms of these oxides, and a substantial portion of these oxides within the soils existed in crystalline form. Among the soil series studied, Itagunmodi series exhibited the highest amount of DCB- and oxalate extractable Fe oxides, while Iwo series had the highest content of Fe and Al oxides extracted by sodium pyrophosphate solution. Importantly, the presence of Fe oxides were found to negatively impact the reactivity of SOM in the soils.

Ceramic materials in Na2O-CaO-P2O5 system were obtained by firing cement-salt stone made from pastes based on powder mixtures including calcium citrate tetrahydrate Ca3(C6H5O7)2∙4H2O, monocalcium phosphate monohydrate (MCPM) Ca(H2PO4)2∙H2O and/or sodium dihydrogen phosphate NaH2PO4. The phase composition of the obtained samples of cement-salt stone after adding water, hardening and drying included brushite CaHPO4∙2H2O, monetite CaHPO4 and also unreacted Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and/or NaH2PO4. The phase composition of ceramics in Na2O-CaO-P2O5 system obtained by firing cement-salt stone was formed due to thermal conversion of hydrated salt and heterophase reactions between components presented in samples during firing. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O and Ca(H2PO4)2∙H2O after firing at 900 °C included β-calcium pyrophosphate (CPP) β-Ca2P2O7. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, and NaH2PO4 after firing at 900 °C included β-sodium rhenanite β-CaNaPO4. The phase composition of ceramic samples based on powder mixture of Ca3(C6H5O7)2∙4H2O, Ca(H2PO4)2∙H2O and NaH2PO4 after firing at 900 °C included β-Ca2P2O7, β-CaNaPO4, double calcium-sodium pyrophosphate Na2CaP2O7, and Na-substituted tricalcium phosphate Сa10Na(PO4)7. Obtained ceramic materials in Na2O-CaO-P2O5 system including biocompatible and biodegradable phases could be important for treatments of bone tissue defects by means of approaches of regenerative medicine.

Background and aim Iron plaque (IP) on rice (Oryza sativa) root surface consists of reddish brown IP (RIP) and non-reddish brown IP (NRIP), however, their extraction and characterization need further studies. Methods A reliable method combining chemical and X-ray diffraction (XRD) analysis was introduced to discriminate RIP and NRIP on root surface of rice plants subjected to different phosphate (P) treatments. Results RIP appeared only on P-deficient rice root surface, and NRIP occurred on both P-deficient and P-sufficient rice root surface. Both RIP and NRIP could be extracted by dithionite-citrate-bicarbonate while only NRIP could be extracted by 0.1 M tetrasodium pyrophosphate (Na₄P₂O₇) specifically. NRIP on P-sufficient root surface was 2.42 times ofthat on P-deficient plants. Iron speciation analysis showed that the total, amorphous and crystalline iron on P-deficient root surface were 1.47-, 1.50- and 1.35-times of those of P-sufficient plants, respectively. XRD analysis further confirmed that IP on both P-sufficient and P-deficient root surface presented as amorphous features. Dominant minerals of NRIP were iron phosphates, while those of RIP were ferric (hydr)oxides. The specific removal effect of 0.1 M Na₄P₂O₇ for NRIP was also verified by XRD. Conclusion In this study, phosphate levels in nutrient solution significantly influence the formation of RIP and NRIP on rice root surface. Main components of RIP and NRIP are ferric (hydr)oxides and iron phosphates, respectively. They can be separated by 0.1 M Na₄P₂O₇.

Objective To assess the effects for controlling extrinsic tooth stain of a whitening toothpaste containing 10% high cleaning silica, 0.5% sodium phytate and 0.5% sodium pyrophosphate, in comparison with a negative control toothpaste. Methods A total of 86 adults who met with the inclusion and exclusion criteria were invited to take part in the study. They were distributed into test and control groups randomly. At baseline, 4 weeks and 8 weeks, the same examiner provided the clinical examinations, including evaluations of oral soft and hard tissues and measurements of tooth stain of the anterior teeth using the Lobene Stain Index. Adverse events and any changes in general health conditions of the patients were monitored. Results When the study was completed, comparisons between patients in test and control groups yielded statistically significant differences in Lobene stain adjusted mean area score [0.83 (0.05) vs. 1.13 (0.05)], Lobene stain adjusted mean intensity score [0.99 (0.06) vs. 1.32 (0.06)] and Lobene stain adjusted mean composite score [1.45 (0.13) vs. 2.50 (0.13)] (All, P  < 0.001). Patients in the test group exhibited reductions of 26.55%, 25% and 42%, respectively in Lobene stain area, intensity and composite scores, relative to patients in the control group. Comparisons within groups showed that all three Lobene scores at 8 weeks in both groups were lower than those at baseline (All, P  < 0.001). Conclusion This study demonstrates that 8-week use of a toothpaste containing 10% high cleaning silica, 0.5% sodium phytate and 0.5% sodium pyrophosphate can effectively reduce extrinsic tooth stain. Trial registration NCT04238429 (before enrollment of the first participant). Data register: March 4, 2018.

The silicon (Si) cycle is an important driver of the long-term climate cycle and Si is an important micronutrient for some plant species, but our understanding of Si partitioning into various soil fractions remains incomplete. The biogeochemical processes that result in the various Si fractions are poorly constrained in most soil environments, especially in soil horizons that are partially-cemented with Si, such as fragipans. Here, we investigate the fractionation of Si, iron (Fe), aluminum (Al), and Mn (manganese) in fragipans and compare these fractions to non-fragipan soils, including sandstone- and limestone-derived soils. We performed a sequential silicon fractionation scheme using water (4 h and 21 day), sodium pyrophosphate, and citrate dithionite extractions. On average, fragipan soils contained significantly greater extractable Si (6.08 ± 1.87, µ ± 1sd) compared to non-fragipans (2.17–3.55 ± 0.49–0.81). More Si was released from fragipan horizons following the 21 day water, sodium pyrophosphate and citrate dithionite extractions suggesting the presence of a silica pool not present in other soils. A significant relationship was observed between fragipan dithionite-extractable Si and Fe (r2 = 0.64, y = 1.06x − 98.85), and the slope of this relationship was significantly greater when compared to other horizons. Water-extractable Si correlated with dithionite-extractable Si, which may indicate overlap between these fractions. A more rigorous fractionation scheme may be required to better differentiate these Si pools. These results suggest that additional Si sorbs to the surfaces of secondary, crystalline Fe oxides and at a potentially greater rate, which may have implications for fragipan genesis.