Search Results (85)

Rare earth elements (REEs) have garnered significant global attention due to their essential role in advanced technologies. Sri Lanka is endowed with various REE-bearing minerals, including the apatite-rich deposit in the Eppawala area, commonly known as Eppawala rock phosphate (ERP). However, direct extraction of REEs from ERP is technically challenging and economically unfeasible. This study introduces a novel, integrated approach for recovering REEs from ERP as a by-product of nitrophosphate fertilizer production. The process involves nitric acid-based acidolysis of apatite, optimized at 10 M nitric acid for 2 h at 70 °C with a pulp density of 2.4 mL/g. During cooling crystallization, 42 wt% of calcium was removed as Ca(NO₃)₂.4H₂O while REEs remained in the solution. REEs were then selectively precipitated as REE phosphates via pH-controlled addition of ammonium hydroxide, minimizing the co-precipitation with calcium. Further separation was achieved through selective dissolution in a sulfuric–phosphoric acid mixture, followed by precipitation as sodium rare earth double sulfates. The process achieved over 90% total REE recovery with extraction efficiencies in the order of Pr > Nd > Ce > Gd > Sm > Y > Dy. Samples were characterized for their phase composition, elemental content, and morphology. The fertilizer results confirmed the successful production of a nutrient-rich nitrophosphate (NP) with 18.2% nitrogen and 13.9% phosphorus (as P₂O₅) with a low moisture content (0.6%) and minimal free acid (0.1%), indicating strong agronomic value and storage stability. This study represents one of the pioneering efforts to valorize Sri Lanka’s apatite through a novel, dual-purpose, and circular approach, recovering REEs while simultaneously producing high-quality fertilizer. Full article

This study investigated the effects of acid etching with grape seed extract (GSE)-modified etchants, varying phosphoric acid (PA) concentrations, on endogenous collagenolytic activity of etched dentin, adhesive–dentin (A/D) interfacial formation, and bond strength over time. Three PA concentrations (5%, 10%, and 20%) were combined with 2% GSE (5PA/GSE, 10PA/GSE, and 20PA/GSE) and compared to a control (CT) group using 32% PA gel (3M Universal Scotchbond etchant). Seventy-four caries-free human third molars were sectioned to expose dentin surfaces, which were etched and analyzed. In situ zymography with confocal laser microscopy was used to assess endogenous collagenolytic activity in etched dentin specimens. For A/D interfacial morphology and bond strength, etched dentin was bonded with Adper Single Bond Plus adhesive (3M ESPE) and composite buildup. The interfacial morphology of A/D specimens was evaluated using either Goldner’s trichrome staining under light microscopy after microtomy sectioning or scanning electron microscopy. A/D specimens were stored in either TESCA buffer or collagenase solution and tested immediately (IM) or at multiple time points over one year using the microtensile bond strength (μTBS) test. Data were analyzed by one- or three-way ANOVA followed by Games–Howell or Tukey’s tests (α = 0.05). GSE-modified etchants significantly reduced endogenous collagenolytic activity (p < 0.05). Although GSE-modified etchants resulted in thinner A/D interfaces, the bond strength remained unaffected (p > 0.05). Bond strength stability was prolonged up to one year with 5PA/GSE and 10PA/GSE (p < 0.001), while CT or 20PA/GSE showed significant degradation by 17 weeks (p < 0.01). Storage in the more aggressive collagenase solution did not further reduce the bond strength compared to TESCA buffer (p = 0.966). Acid etching with GSE-modified etchants effectively inhibits endogenous MMP-mediated collagenolytic activity. At 5% and 10% PA, this approach enhances the stability of the A/D bond strength, offering a promising modification for dentin bonding protocols. Full article

The concurrent preservation of structural integrity and improvement of electrical conductivity in FeP₂ anodes presents a persistent challenge. Herein, FeP₂ nanoparticles embedded within a 3D N-doped honeycomb-like carbon framework composite (FeP₂@NHC) are synthesized through a phosphorization process with a honeycomb-like Fe₃C@NHC as a precursor. The in situ incorporation of FeP₂ nanoparticles into the 3D carbon matrix effectively restrains the aggregation, pulverization, and stripping of material during cycling, and significantly enhances reaction kinetics and structural stability, achieving a superior electrochemical performance. Specifically, FeP₂@NHC electrodes demonstrate remarkable reversible capacity (1433.9 mA h g⁻¹ at 0.1 A g⁻¹), excellent rate-capability (399.9 mA h g⁻¹ at 10 A g⁻¹), and ultra-long cycle life (631.5 mA h g⁻¹ after 1000 cycles at 2 A g⁻¹). Moreover, XRD analysis reveals that iron-rich Fe₃C and Fe₃O₄ precursors can react with NaH₂PO₂ to form FeP₂ and FeP, respectively. This study offers a rational and practical strategy for designing other phosphorus-rich metal phosphide anode materials. Full article

Technical albumen (TA) is liquid waste from egg processing enterprises and occupies a share of 10–15% of the waste. Proteins have the property at the isoelectric point of weakening their repulsive forces. This property is the basis of a TA recovery method using pretreatment to reduce moisture before drying. In this study, we present the results of a TA processing method using two types of citric and phosphoric acids based on thermal–acid coagulation as an alternative to spray drying. By analyzing physicochemical and microbiological indicators, the raw TA and the finished product are described. In this study, the characteristics of raw TA and its final product are presented. TA contains mainly water, fat, and protein, including all essential amino acids, all of the proteins of the egg white, and some of the yolk. Initially, TA is significantly microbiologically contaminated. A better yield was obtained when using citric acid 97.79% instead of phosphoric acid. The final dried egg product from TA has a protein content of 46% and a fat content of 33%. The dried egg products undergo changes in the lipid and protein fraction during storage, but the values remain low TBARS to 4 mg MDA/kg. Microbiological contamination has decreased due to a decrease in water activity to a level that meets the requirements of European legislation for the processing of animal by-products (ABPs) and uses as feed. Full article

Carbon (C) and phosphorus (P) in soil are closely related to plantation types in afforestation practices. However, the trade-off between soil C and P in response to different restoration models on degraded hilly land is still not clear. In this study, four restoration patterns, including natural recovered shrubland (NS), Castanopsis hystrix plantation (CH), 10-species mixed plantation (10MX), and 30-species mixed plantation (30MX) were selected, and the physicochemical properties and readily oxidized carbon (ROC) in different layers of 1 m depth soil were measured to understand the effects of natural restoration and artificial afforestation on soil P and C pool and their trade-off on degraded hilly land in southern China. The results indicate that the total P (TP) content in each soil layer was observed to follow the order of CH > 10MX > 30MX > NS, with monoculture (CH) exhibiting higher levels of TP than mixed plantation. However, the soil C storage of NS (59.61 t hm⁻²) and 30MX (57.71 t hm⁻²) was similar, while 10MX boasted the highest C storage (64.99 t hm⁻²) of the four restoration patterns, with CH being the lowest (42.75 t hm⁻²). In deep soil layers (20–100 cm), the 10MX plantation presented the highest for both the C pool index (CPI) and C pool management index (CMI). Moreover, the structural equation model (SEM) revealed that the soil CMI was directly regulated by the levels of soil available P and total N, while soil C pool activity was directly influenced by soil pH. Thus, our study suggests that compared to mixed plantations, the monoculture plantation (CH) demonstrates lower P uptake and utilization, resulting in a higher soil P content. Furthermore, 10MX plantation showed a superior C fixation capacity over those with 30MX and monoculture plantations. These suggests that the trade-off between soil C and P contents was commonly observed among different plantation restoration patterns. Therefore, afforestation with different tree composition and nutrient regulation is necessary for maintaining the balance between soil C and P and keeping the sustainability of plantation management in the degraded hilly lands. Full article

In this study, the mechanochemical preparation of nanocrystalline CaF₂:Sm³⁺ by ball milling calcium acetate hydrate, samarium (III) acetate hydrate, and ammonium fluoride is reported. The photoluminescence of the as-prepared CaF₂:Sm³⁺ shows predominantly Sm^3+ 4G_5/2 → ⁶H_J(J = 5/2, 7/2, 9/2, and 11/2) f-f luminescence, but intense electric dipole allowed 4f⁵5d (T_1u) → 4f^6 7F₁ (T_1g) luminescence by Sm²⁺ was generated upon X-irradiation. In comparison with the co-precipitated CaF₂:Sm³⁺, the conversion of Sm³⁺$\to$ Sm²⁺ in the ball-milled sample upon X-irradiation is significantly lower. Importantly, the present results indicate that the crystallite size and X-ray storage phosphor properties of the lanthanide-doped nanocrystalline CaF₂ can be modified by adjusting the ball milling time, dopant concentration and post-annealing treatment, yielding crystallite sizes as low as 6 nm under specific experimental conditions. Full article

This review contains data on a wide class of microporous materials with frameworks belonging to the sodalite topological type. Various methods for the synthesis of these materials, their structural and crystal chemical features, as well as physical and chemical properties are discussed. Specific properties of sodalite-related materials make it possible to consider they as thermally stable ionic conductors, catalysts and catalyst carriers, sorbents, ion exchangers for water purification, matrices for the immobilization of radionuclides and heavy metals, hydrogen and methane storage, and stabilization of chromophores and phosphors. It has been shown that the diversity of properties of sodalite-type materials is associated with the chemical diversity of their frameworks and extra-framework components, as well as with the high elasticity of the framework. Full article

Phosphogypsum is a by-product of the wet-process phosphoric acid production, and it is rich in Ca and S. Long-term storage of Phosphogypsum can cause serious pollution to the environment; therefore, promoting the sustainable utilization of Phosphogypsum is crucial. This study proposes the use of Phosphogypsum and silicic acid in a sodium hydroxide solution for the hydrothermal synthesis of porous calcium silicate hydrate adsorbent, which is used for adsorbing Fe²⁺ from simulated hydrochloric acid pickling wastewater. Under the optimal synthesis conditions (37.5 g/L of NaOH, calcium/silicon ratio of 1.0, liquid/solid ratio of 15:1 mL/g, 110 °C, and 4 h), the conversion rate of SO₄²⁻ in Phosphogypsum is 87.41%. Porous calcium silicate hydrate exhibits excellent OH⁻ release capability in Fe²⁺-containing pickling wastewater. The adsorption process for Fe²⁺; is mainly chemical adsorption, involving ion exchange between Ca²⁺ and Fe²⁺, as well as complexation reactions of O-Si-O group, -OH group, and Si-O group with Fe²⁺. This technology aims to provide a solution for the sustainable utilization of Phosphogypsum and the recovery of Fe²⁺ from pickling wastewater, which has significant practical importance. Full article

Black phosphorous (BP) is a novel composite material. Its carrier mobility can reach more than 1000 cm²·V⁻¹·s⁻¹ and has a direct bandgap adjustable from 0.3 to 1.5 eV with thickness, so its photovoltaic performance is good. These properties show great potential for applications in many fields, such as energy storage, sensors, biomedicine, and environmental treatment. With the deepening of research, it is found that the instability of BP under natural environmental conditions and the limitations of its preparation limit its development, while combining with other materials can further optimize its performance, which not only improves the mechanical properties of the material but also gives it new functions. Based on this, this paper summarizes the preparation and optical properties of highly stable metals and their compounds/BP-based nanomaterials in recent years, highlights the progress of their application in photocatalytic hydrogen evolution, and gives an outlook on the challenges and opportunities for the future development of BP in photocatalysis. Full article

To seek an appropriate stabilization and remediation scheme for cadmium (Cd) and arsenic (As) pollution in farmland, a typical polluted soil sample was selected from a mining area in Southwest China for a soil box simulation experiment. Biochar (BC), a modified type of biochar made from rice husk with different mass ratios of ferric chloride and rice husk, was set up (the mass ratio of ferric chloride to rice husk was 1:9 (defined as LFB), 3:7 (defined as MFB), and 5:5 (defined as HFB) and the control group (BL)) to explore the effects of soil water and fertilizer loss, the bioavailability of Cd and As, and the bioenrichment effects of plant organs during the growth period of rice. The results showed that the porous structure and large specific surface area of biochar effectively regulated soil aggregate composition and improved soil water holding capacity. Compared to the BL treatment, soil water storage under the four carbon-based material control modes increased from 8.98% to 14.52%. Biochar has a strong ion exchangeability and can absorb soil ammonium, nitrogen, and phosphoric acid groups, effectively inhibiting the loss of soil fertilizer. Biochar improves soil pH and reduces the specific gravity of exchangeable Cd. In addition, the oxygen-containing functional groups in biochar can react with metals in a complex manner. The diethylenetriaminepentaacetic acid (DTPA) concentrations of Cd in soils treated with BC, LFB, MFB, and HFB were 79.69%, 72.92%, 64.58%, and 69.27% lower, respectively, than those treated with BL. In contrast, the Fe³⁺ in ferric chloride combines with As after hydrolysis and oxidation to form amorphous ferric arsenate precipitates or insoluble secondary minerals. Therefore, the curing effect of the modified biochar on As was more potent than that of applied biochar alone. In conclusion, ferric chloride-modified biochar can effectively inhibit the effects of water and fertilizer loss in farmland soil and realize cross-medium long-term inhibition and control of combined Cd and As pollution. Full article

Aluminum garnets display exceptional adaptability in incorporating mismatching elements, thereby facilitating the synthesis of novel materials with tailored properties. This study explored Ce³⁺-doped Tb₃Al_5−xSc_xO₁₂ crystals (where x ranges from 0.5 to 3.0), revealing a novel approach to control luminescence and photoconversion through atomic size mismatch engineering. Raman spectroscopy confirmed the coexistence of garnet and perovskite phases, with Sc substitution significantly influencing the garnet lattice and induced A_1g mode softening up to Sc concentration x = 2.0. The Sc atoms controlled sub-eutectic inclusion formation, creating efficient light scattering centers and unveiling a compositional threshold for octahedral site saturation. This modulation enabled the control of energy transfer dynamics between Ce³⁺ and Tb³⁺ ions, enhancing luminescence and mitigating quenching. The Sc admixing process regulated luminous efficacy (LE), color rendering index (CRI), and correlated color temperature (CCT), with adjustments in CRI from 68 to 84 and CCT from 3545 K to 12,958 K. The Ce³⁺-doped Tb₃Al_5−xSc_xO₁₂ crystal (where x = 2.0) achieved the highest LE of 114.6 lm/W and emitted light at a CCT of 4942 K, similar to daylight white. This approach enables the design and development of functional materials with tailored optical properties applicable to lighting technology, persistent phosphors, scintillators, and storage phosphors. Full article

Today, BaFBr crystals activated by europium ions are used as detectors that store absorbed energy in metastable centers. In these materials, the image created by X-ray irradiation remains stable in the dark for long periods at room temperature. As a result, memory image plates are created, and they are extended to other types of ionizing radiation as well. Despite significant progress towards X-ray storage and readout of information, the mechanisms of these processes have not been fully identified to date, which has hindered the efficiency of this class of phosphors. In this study, using photoluminescence (PL), optical absorption (OA), Raman spectroscopy (RS), and atomic force microscopy (AFM), the luminescence of oxygen vacancy defects to BaFBr crystals irradiated with 147 MeV ⁸⁴Kr and 24.5 MeV ¹⁴N ions at 300 K to fluences (10¹⁰–10¹⁴) ion/cm² was investigated. BaFBr crystals were grown by the Shteber method on a special device. Energy-dispersive X-ray spectroscopy (EDX) analysis revealed the presence of Ba, Br, F, and O. The effect of oxygen impurities present in the studied crystals was considered. The analysis of the complex PL band, depending on the fluence and type of ions, showed the formation of three types of oxygen vacancy defects. Macrodefects (tracks) and aggregates significantly influence the luminescence of oxygen vacancy defects. The creation of hillocks and tracks in BaFBr crystals irradiated with 147 MeV ⁸⁴Kr ions is shown for the first time. Raman spectra analysis confirmed that BaFBr crystals were amorphized by 147 MeV ⁸⁴Kr ions due to track overlap, in contrast to samples irradiated with 24.5 MeV ¹⁴N ions. Raman and absorption spectra demonstrated the formation of hole and electron aggregate centers upon swift heavy ions irradiation. Full article

Surface chemistry and bulk structure jointly play crucial roles in achieving high-performance supercapacitors. Here, the synergistic effect of surface chemistry properties (vacancy and phosphorization) and structure-derived properties (hollow hydrangea-like structure) on energy storage is explored by the surface treatment and architecture design of the nanostructures. The theoretical calculations and experiments prove that surface chemistry modulation is capable of improving electronic conductivity and electrolyte wettability. The structural engineering of both hollow and nanosheets produces a high specific surface area and an abundant pore structure, which is favorable in exposing more active sites and shortens the ion diffusion distance. Benefiting from its admirable physicochemical properties, the surface phosphorylated MnCo₂O_4.5 hollow hydrangea-like structure (P-MnCoO) delivers a high capacitance of 425 F g⁻¹ at 1 A g⁻¹, a superior capability rate of 63.9%, capacitance retention at 10 A g⁻¹, and extremely long cyclic stability (91.1% after 10,000 cycles). The fabricated P-MnCoO/AC asymmetric supercapacitor achieved superior energy and power density. This work opens a new avenue to further improve the electrochemical performance of metal oxides for supercapacitors. Full article

Medical imaging instrumentation is mostly based on the use of luminescent materials coupled to optical sensors. These materials are employed in the form of granular screens, structured crystals, single transparent crystals, ceramics, etc. Storage phosphors are also incorporated in particular X-ray imaging systems. The physical properties of these materials should match the criteria required by the detective systems employed in morphological and functional biomedical imaging. The systems are analyzed based on theoretical frameworks emanating from the linear cascaded systems theory as well as the signal detection theory. Optical diffusion has been studied by different methodological approaches, such as experimental measurements and analytical modeling, including geometrical optics and Monte Carlo simulation. Analysis of detector imaging performance is based on image quality metrics, such as the luminescence emission efficiency (LE), the modulation transfer function (MTF), the noise power spectrum (NPS), and the detective quantum efficiency (DQE). Scintillators and phosphors may present total energy conversion on the order of 0.001–0.013 with corresponding DQE in the range of 0.1–0.6. Thus, the signal-to-noise ratio, which is crucial for medical diagnosis, shows clearly higher values than those of the energy conversion. Full article

Seed aging is a common physiological phenomenon during storage which has a great impact on seed quality. An in-depth analysis of the physiological and molecular mechanisms of wheat seed aging is of great significance for cultivating high-vigor wheat varieties. This study reveals the physiological mechanisms of wheat seed aging in two cultivars differing in seed vigor, combining metabolome and transcriptome analyses. Differences between cultivars were examined based on metabolomic differential analysis. Artificial aging had a significant impact on the metabolism of wheat seeds. A total of 7470 (3641 upregulated and 3829 downregulated) DEGs were detected between non-aging HT and LT seeds; however, 10,648 (4506 up and 6142 down) were detected between the two cultivars after aging treatment. Eleven, eight, and four key metabolic-related gene families were identified in the glycolysis/gluconeogenesis and TCA cycle pathways, starch and sucrose metabolism pathways, and galactose metabolism pathways, respectively. In addition, 111 up-regulated transcription factor genes and 85 down-regulated transcription factor genes were identified in the LT 48h group. A total of 548 metabolites were detected across all samples. Cultivar comparisons between the non-aged groups and aged groups revealed 46 (30 upregulated and 16 downregulated) and 62 (38 upregulated and 24 downregulated) DIMs, respectively. Network analysis of the metabolites indicated that glucarate O-phosphoric acid, L-methionine sulfoxide, isocitric acid, and Gln-Gly might be the most crucial DIMs between HT and LT. The main related metabolites were enriched in pathways such as glyoxylate and dicarboxylate metabolism, biosynthesis of secondary metabolites, fatty acid degradation, etc. However, metabolites that exhibited differences between cultivars were mainly enriched in carbon metabolism, the TCA cycle, etc. Through combined metabolome and transcriptome analyses, it was found that artificial aging significantly affected glycolysis/gluconeogenesis, pyruvate metabolism, and glyoxylate and dicarboxylate metabolism, which involved key genes such as ACS, F16P2, and PPDK1. We thus speculate that these genes may be crucial in regulating physiological changes in seeds during artificial aging. In addition, an analysis of cultivar differences identified pathways related to amino acid and polypeptide metabolism, such as cysteine and methionine metabolism, glutathione metabolism, and amino sugar and nucleotide sugar metabolism, involving key genes such as BCAT3, CHI1, GAUT1, and GAUT4, which may play pivotal roles in vigor differences between cultivars. Full article