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Yttrium–magnesium alloys are commonly employed as processing additives in magnesium alloy materials. Incorporating yttrium into magnesium alloys via Y-Mg intermediate alloys not only minimizes oxidation and burn-off loss but also simplifies operational procedures. Utilizing yttrium–magnesium alloys ensures a stable composition and reliable quality of magnesium alloy products, while contributing to reduced production costs and minimized environmental pollution. In this study, a molten salt co-reduction method was developed for the preparation Y-Mg intermediate alloys. The electrochemical co-reduction behaviors of Y(III) and Mg(II), as well as the transient states of Y-Mg intermediate alloys, were systematically investigated by transient electrochemical techniques. Results indicated that the reduction of Y(III) at the molybdenum (Mo) cathode is a reversible electrochemical process, whereas the reduction of Mg(II) is irreversible and diffusion-controlled. The diffusion coefficient of Y(III) and Mg(II) in the fluoride salt at 1000 °C were determined to be 3.98 × 10−5 cm2/s and 1.16 × 10−3 cm2/s, respectively. Electrochemical calculations revealed that the reduction of Y(III) involves a single-step transfer of three electrons, while Mg(II) involves a single-step transfer of two electrons. The corresponding electrode reactions are Y(III) + 3e−→Y and Mg(II) + 2e−→Mg, respectively. A Y-Mg alloy sample prepared by constant-current molten salt electrolysis primarily consists of the MgY phase with a composition of 88.38 wt% yttrium and 11.62 wt% magnesium.

In this study we developed well validated thermodynamic models for solution behavior and solid-liquid equilibrium for all fluoride binary systems, for which activity data are available. The subject of modeling study are 5 fluoride systems of the type 1-1 (HF-H2O, NaF-H2O, KF-H2O, RbF-H2O, and CsF-H2O) and one of 1-2 type (H2SiF6-H2O) from low to very high concentration at 298.15 K. Models are developed on the basis of Pitzer ion interactions approach. The recommendations on mean activity coefficients (γ±) have been used to construct the model for HF-H2O system. To parameterize models for all other 5 binary systems we used all available raw experimental osmotic coefficients data (φ) for whole concentration range of solutions, and up to saturation point. The predictions of new developed here models are in excellent agreement with experimental osmotic coefficients data, and with recommendations on activity coefficients in binary solutions from low to very high concentration: up to 20 mol. kg−1 in HF-H2O, and up to 35.6 mol.kg−1 in CsF-H2O. The Deliquescence Relative Humidity (DRH (%)) and thermodynamic solubility products (as ln Kosp) of 4 solid phases [NaF(s), KF.2H2O(s), RbF(s), and CsF(s)] have been determined on the basis of evaluated model parameters and using experimental m(sat) solubility data.

China’s rare earth reserves and consumption are the highest in the world. Rare earth metals and alloys play a pivotal role in the domains of permanent magnetic materials, hydrogen storage materials, luminescent materials, abrasive materials, etc. The molten salt electrolysis process is the most widely used method for producing light rare earth metals and alloys in China, with distinct advantages such as continuous production and short process flow. This article focuses on the process technology of preparing rare earth metals and alloys by electrolyzing rare earth oxides in fluoride systems. This article summarizes the effects of process parameters such as cathode and anode structures, electrolysis temperature, and current density on the direct recovery and current efficiency of the preparation of light rare earth metals (La, Ce, Pr, Nd), RE–Mg (RE for rare earth) alloys, RE–Al alloys, RE–Ni alloys, and other rare earth alloys. Meanwhile, the disadvantages of the electrolytic cells and electrode configurations that are currently used in industrial production are discussed. Accordingly, the future prospects of molten salt electrolysis technology in the preparation of rare earth metals and alloys are clarified.

Beryllium-containing halide melts can be used for the electrolytic manufacturing and refining of beryllium and for reprocessing spent nuclear fuel. Data on the melting temperatures of salt mixtures are of importance for the organization of manufacturing processes using them. The complexity of researching salt systems containing beryllium fluoride is related to a number of factors, which include the hygroscopicity of a salt, corrosion activity with respect to construction materials, and salt vapor toxicity. In this relation, all preparation operations are performed in an argon atmosphere using a glove box. Differential thermal analysis (DTA) of samples is also performed in a dry pure argon atmosphere. Platinum and beryllium oxide crucibles are used. These materials exhibit the best corrosion resistance against the molten salt media under study. The fusibility diagrams of beryllium fluoride with alkali-metal (Li, Na, K, Cs) chlorides are reported; they are based on DTA and X-ray diffraction data. Coordinates of eutectic points are determined. In the beryllium fluoride range concentration from an individual alkali-metal chloride to the corresponding eutectic, the measuring results are represented in the form of approximating polynomials of the concentration dependence of the melting temperature of the BeF 2 –MCl (M = Li, Na, K, Cs) systems. The fusibility of salt mixtures of lithium and potassium chloride eutectic with beryllium fluoride is studied. The most low-melting mixture among the compositions under study contains 35 mol % beryllium fluoride and melts at 331°C. The absence of ternary compounds in the systems is shown. To identify phases, X-ray diffraction analysis is used; it shows the presence of corresponding alkali-metal chlorides in the solid phases of the systems. The presence of beryllium fluoride is determined using a characteristic absorption peak in infrared spectra. A unique method is used for the distillation of beryllium fluoride prepared by the decomposition of ammonium fluoroberyllate. In view of the glass-forming ability of beryllium fluoride, data on the melting temperatures of salt mixtures enriched in the component are evaluative.

ObjectivesTo evaluate the clinical performance of self-assembling peptides versus fluoride-based delivery systems in post-orthodontic white spot lesions.Materials and methodsThe participants were randomly assigned into two groups (n = 58) according to the remineralizing agent used, where (A) group represented participants receiving a varnish containing 22.600 fluoride ppm and tricalcium phosphate, while the second group (B) represented participants receiving self-assembling peptide. The remineralizing process of the white spot lesion was assessed using the DIAGNOdent pen and ICDAS scoring system according to the time when the remineralizing agent was used (T), where T0 represented the score taken at baseline. T1 represented the score taken after 3 months of follow-ups and T2 score represented the score taken after 6 months of follow-up. Data were collected and statistically analyzed. The parametric data: two-way ANOVA was used to test the effect of interaction among different variables. The non-parametric data: Mann–Whitney test was used. The significance level was set at p ≤ 0.05.ResultsThere was a quantitative statistically significant difference via DIAGNOpen readings between Group A (fluoride material) and Group B (self-assembling peptides). The highest mean value of 10.51 was found in Group A, while the least mean value of 6.45 was found in Group B. Besides, there was a significant difference in each group concerning the time factors T0, T1, and T2 groups where (p < 0.001. As for the qualitative results concerning the ICDAS score, there was no significant difference between the two groups along with the follow-up periods T0, T1, and T2 where the p value is equal to 0.064, 0.087, and 0.277 respectively.ConclusionsThe visual assessment using ICDAS reveals that the biomimetic remineralization using self-assembling peptides and the fluoride-based varnish material showed a similar effect in masking post-orthodontic white spot lesions. However, the laser fluorescence using DIAGNOpen showed that the self-assembling peptides reveal higher performance in subsurface remineralization than the fluoride-based varnish material. Therefore, self-assembling peptides are considered a promising material for lesion regression in post-orthodontics white spot lesions.Clinical relevanceSelf-assembling peptide SAP-14 is a new approach to reverse and mask off post-orthodontics white spot lesions.

The present study was undertaken to evaluate the fluoride status in the general healthy population of Barcelona. Serum and urine fluoride ionic concentration was determined in a random sample of 250 subjects (age range 15-90 yr) by the Orion fluoride electrode system to determine the normal range of fluoride in this population. The results obtained show that in the general population of Barcelona, fluoride ionic serum concentration ranges between 1 and 47 microg/L (x = 17.5 +/- 9.7 microg/L) and fluoride ionic urine concentration ranges between 156 and 1990 microg/24 h (x = 671 +/- 373 microg/24 h). The mean serum fluoride concentration of the younger population was shown to be significantly greater (p < 0.05) than that of the older group. No sex-related difference was found.

Purpose Glass ionomer fissure sealant (GIS) and fluoride varnish (NaFV) are two preventive interventions applicable to pre-school children. However, their application effects on young children’s behaviour are understudied. The study compared the effects of GIS and NaFV applications on dental anxiety (DA), cooperativeness and pain level in pre-school children when applied to primary second molars in outreach settings. Methods Four hundred and thirteen children were recruited for the study, out of which 228 were allocated to NaFV group whilstand 185 allocated to the GIS group. One calibrated examiner screened and randomly allocated the children into either group. Another calibrated examiner recorded the children’s DA level and cooperativeness with Frankl Behaviour Rating Scale (FBRS) and Venham Behaviour Rating Scale (VBRS) throughout the treatment period. Subjects self-reported their pain levels using Wong–Baker Faces Scale (WBFS). Results Significant difference in postoperative anxiety was found using VBRS, with children in NaFV group having more positive scores post-treatment ( p  = 0.016). Only the type of preventive interventions significantly affected postoperative DA and patient cooperation ( p  = 0.032), whereas no other clinical findings and socio-demographic factors significantly influenced the children’s behaviour postoperatively. Conclusion NaFV application is associated with less DA and more cooperative behaviour in pre-school children compared to GIS application although similar pain levels were recorded.

ObjectivesThis in vitro study aimed assessing the remineralization potential of three commercial fluoride-based toothpastes in permanent teeth with natural white spot lesions (WSLs). A multidisciplinary approach based on Raman microspectroscopy (RMS), Scanning electron microscopy (SEM), Energy-dispersive x-ray spectroscopy (EDS), and Vickers microhardness (VMH) was exploited.MethodsN = 12 human molars with natural WSLs in the proximal-vestibular zone were selected and divided into 4 groups (n = 3) according to the different treatments: HAF (hydroxyapatite with fluoride ions); SMF (sodium monofluorophosphate with arginine); SF (sodium fluoride with enzymes), and CTRL (untreated group). All toothpastes tested contained 1450 ppm of fluoride. Teeth samples were submitted to the following protocol: a 7-day pH cycling treatment, with two daily exposures (2 min each time) to the commercial toothpastes described above. The surface micromorphology (SEM), the chemical/elemental composition (RMS and EDS), and the Vickers microhardness (VMH) were evaluated. Statistical analysis was performed.ResultsA remarkable remineralization of WSLs in SEM images was observed in all treated groups compared to CTRL. In particular, HAF and SF displayed higher values of VMH, phosphates amount (I960), crystallinity (FWHM960), and lower ones of C/P (I1070/I960) with respect to CTRL. Intermediate values were found in SMF, higher than CTRL but lower with respect to HAF and SF. As regards the Ca/P ratio, statistically significant differences (p < 0.05) were found between SF and the other groups.ConclusionsAll the tested dentifrices have shown to remineralize the WSLs. SF and HAF have comparable capability in hardness recovery and crystallinity; however, SF shows the best remineralizing potential according to both micromorphological and chemical analyses.Clinical relevanceThe daily use of toothpastes containing hydroxyapatite partially replaced with fluoride, sodium monofluorophosphate with arginine and sodium fluoride toothpaste associated with enzymes represents a preventive, therapeutic, effective, and non-invasive tool for remineralize WSLs.

Background Fluorosis caused by excess intake of fluoride can affects various soft tissues of the body, such as the gastrointestinal tract, blood, brain tissues and thyroid gland apart from dental fluorosis and skeletal fluorosis. Nonskeletal fluorosis is considered reversible if diagnosed early and treated promptly. Therefore, diagnostic methods that can be easily performed even by primary health care workers and depict any ongoing health problems, should be validated. Dental fluorosis, assessment of fluoride in urine and water are tests that fulfill these requirements. To date, no study has correlated haemoglobin (Hb) with dental fluorosis; moreover, studies focusing on intelligence quotient (IQ) had conflicting results and need further research. Hence, study was conducted to determine any relationship among different fluoride assessment parameters (severity of dental fluorosis, fluoride level in urine and drinking water) with IQ status and hemoglobin level of children aged 8–12 years, affected with or without dental fluorosis. Methods A total of 300 children aged 8–12 years were evaluated for dental fluorosis via Dean’s index, IQ level via Raven’s coloured progressive matrices test, Hb level, and fluoride content in water and urine. Results Water fluoride, age and gender were significantly associated with Hb. Intelligence was significantly related to urinary fluoride levels. Presence or absence of dental fluorosis and its severity were not significantly related to IQ or Hb. Conclusions Excess fluoride intake has adverse effects on hematological parameters and children’s cognitive neurodevelopment, which were evaluated by current fluoride exposure markers, i.e., water and urinary fluoride. However, dental fluorosis cannot be used as a definitive assessment marker for these conditions, as it is not significantly correlated with these conditions.

Fluoride is ubiquitously present throughout the world. It is released from minerals, magmatic gas, and industrial processing, and travels in the atmosphere and water. Exposure to low concentrations of fluoride increases overall oral health. Consequently, many countries add fluoride to their public water supply at 0.7–1.5 ppm. Exposure to high concentrations of fluoride, such as in a laboratory setting often exceeding 100 ppm, results in a wide array of toxicity phenotypes. This includes oxidative stress, organelle damage, and apoptosis in single cells, and skeletal and soft tissue damage in multicellular organisms. The mechanism of fluoride toxicity can be broadly attributed to four mechanisms: inhibition of proteins, organelle disruption, altered pH, and electrolyte imbalance. Recently, there has been renewed concern in the public sector as to whether fluoride is safe at the current exposure levels. In this review, we will focus on the impact of fluoride at the chemical, cellular, and multisystem level, as well as how organisms defend against fluoride. We also address public concerns about fluoride toxicity, including whether fluoride has a significant effect on neurodegeneration, diabetes, and the endocrine system.