Fluoride Uptake Research Articles

Adsorption Isotherm, Kinetic and Thermodynamic Studies for Removal of Fluoride Ions from Drinking Water Using Modified Natural Pumice

This study aimed to modify pumice using aluminum chloride as an adsorbent for defluoridation. Batch and column experiments were carried out to evaluate the effects of pH, initial fluoride concentration, contact time, dose, and temperatur. The modified pumice adsorbent showed good fluoride removal in both batch and column studies. Fluoride up-take was observed to be effective >7%, at pH 6.5-7.5, and adsorption equilibrium time was observed at 60 min. the adsorption results were modelled using kinetic and isotherm models. Experimental data indicated that fluoride adsorption follows the second pseudo-order kinetics model (R2 > 0.99) and fits well with both the Freundlich and Langmuir isotherm models, which showed favorability for the adsorption of fluoride with a maximum capacity of 0.083 mg/g. The negative values of ∆Ho and ∆Go indicate that the adsorption process was feasible, exothermic, and spontaneous. The column performance showed the best fluoride uptake efficiency, with a breakthrough capacity of 0.48 mg/g. The %R was approximately %100 using0.1M NaOH. Fluoride levels in real wells water decreased dramatically (e.g. 4.1-0.88, 7.1-1.54, and 6.2-1.46 mg/L). The results revealed that modified pumice has the potential for fluoride removal from drinking water.

Rosuvastatin effect on atherosclerotic plaque microcalcification

Abstract Background and Aims Atherosclerotic plaque fluorine-18 sodium fluoride (18F-NaF) uptake on positron emission tomography with computed tomography (PET-CT) identifies active microcalcification and has been shown to correlate with clinical instability in patients with cardiovascular (CV) disease. Statin therapy promotes coronary macrocalcification over time. Our aim was to investigate rosuvastatin effect on atheroma 18F-NaF uptake. Methods Subjects with high CV risk but without CV events underwent 18F-NaF-PET-CT in a single-centre. Those with subclinical atherosclerosis and significant 18F-NaF plaque uptake were included in a single-arm clinical trial, treated with rosuvastatin 20mg/daily for six months, and re-evaluated by 18F-NaF-PET-CT. Primary endpoint was reduction in maximum atheroma 18F-NaF uptake in the coronary, aortic or carotid arteries, assessed by the tissue-to-background ratio (TBR). The secondary endpoint was corrected uptake per lesion (CUL) variation. Results Forty individuals were enrolled and 38 included in the pharmacological trial; mean age was 64 years-old, two-thirds were male and most were diabetic. The 10-year expected CV risk was 9.5% (6.0-15.3) for SCORE2 and 31.7±18.7% for ASCVD systems. After six months of rosuvastatin treatment (n=34), low-density lipoprotein cholesterol lowered from 133.6±33.8 to 58.8±20.7 mg.dL-1 (60% relative reduction, p<0.01). There was a significant 19% reduction in maximum plaque 18F-NaF uptake after treatment, from 1.96 (1.78-2.22) to 1.53 (1.40-2.10), p<0.001 (primary endpoint analysis). The secondary endpoint CUL was reduced by 23% (p=0.003). Conclusion In a single-centre non-randomized clinical trial of high CV risk individuals with subclinical atherosclerosis, the maximum atherosclerotic plaque 18F-NaF uptake was significantly reduced after six months of high-intensity statin.Graphical abstractTrial design

Comparative Evaluation of Ion Release and Uptake of Fluoride Varnish Containing Dicalcium Phosphate Dihydrate and Casein Phosphopeptide-Amorphous Calcium Phosphate – An Experimental Approach.

The effectiveness of fluoride varnish may be restricted due to inadequate bioavailability of phosphate and calcium ions in the oral cavity. Dicalcium phosphate dihydrate and Casein phosphopeptide–amorphous calcium phosphate have exhibited ability to enhance absorption of calcium and fluoride. The present study aims to compare the remineralization potential of fluoride varnishes containing DCPD and CPP-ACP. Materials and Method: The ion release, precipitation and surface microhardness of enamel blocks were compared following topical application of various Floride varnishes. Thirty enamel blocks were divided into 3 groups following randomization that included: NaF varnish (Group A), CPP-ACP NaF varnish (Group B) and DCPD- NaF varnish (Group C). Pre- and post-treatment microhardness was evaluated using Vickers Microhardness Tester. UV-Vis Spectroscopy assessed the fluoride release at 2 hrs, 4 hrs and 6 hrs. The uptake of fluoride, calcium and phosphates were determined using SEM-EDX. The statistical significance was tested with One-way ANOVA variance for normality followed by post-hoc tests (p ≤ 0.05). Results: All the groups showed statistically significant increase in microhardness post-treatment (Group A: p=0.03, Group B, C: p=0.00). The mean increase in VHN was Group B (53.67) > Group C (34.75) > Group A (27.40). No significant difference in the F release was noted over time (p=0.00). The fluoride release over all three time intervals was Group C > Group B > Group C. Fluoride, Calcium and Phosphates showed highly significant differences between groups (p=0.00) with Group C > Group A> Group B. Conclusion: The novel NaF-DCPD Varnish displayed a promising remineralization potential, however it cannot be conclusively considered to be superior to the commercially available NaF-CPP ACP Varnish. Further in-vivo investigations need to be undertaken to determine the efficacy of NaF-DCPD varnish to determine its feasibility in clinical practice.

Evaluation of engineered binderless alumina – titania beads for fluoride removal from impaired water resources

Groundwater is often contaminated with various species, with fluoride concentrations being of particular concern. Numerous studies have used adsorbents for fluoride uptake, but most are tested only as powders and not commercially acceptable engineered shapes. Therefore, it was necessary to evaluate the performance of the newly developed Al2O3/TiO2 sorbents in their beaded form to assess their efficacy in comparison to activated alumina granules. Binderless sorbent beads were self-bound with the alumina and titania phases present. The fluoride exchange kinetics of Al2O3/TiO2 beads were comparable to the powdered form. Moreover, the Al2O3/TiO2 beads had higher fluoride loading than commercially available alumina (0.17 meq/g compared to 0.13 meq/g). The Al2O3/TiO2 beads also removed: barium, calcium, lithium, magnesium, manganese, potassium, silica, and strontium from groundwater. In fixed bed column tests, the beads-maintained fluoride within acceptable limits for 42 bed volumes, which substantially outperformed activated alumina (2.5 bed volumes). This study demonstrated that Al2O3/TiO2 beads outperformed commercially available activated alumina materials. Notably, transforming the materials into beaded forms significantly improved their suitability for fluoride removal in industrially relevant fixed-bed column environments. Future studies should focus on enhancing material binding properties to increase crush strength and attrition resistance. A deeper knowledge of regeneration strategies may also facilitate cost reduction.

18F-NaF uptake on vascular PET imaging in symptomatic versus asymptomatic atherosclerotic disease: A meta-analysis.

18F-sodium fluoride (NaF) positron-emission tomography (PET) is increasingly being used to measure microcalcification in atherosclerotic disease in vivo. Correlations have been drawn between sodium fluoride uptake and the presence of high-risk plaque features, as well as its association with clinical atherosclerotic sequelae. The aim of this study was to perform a meta-analysis of NaF uptake on PET imaging and its relation to symptomatic and asymptomatic disease. A systematic review was performed according to PRISMA guidelines, via searching the Ovid MEDLINE, Ovid Embase, Cochrane Library, PubMed, Scopus, and Web of Science Core Collection databases up to May 2024. The search strategy included the terms 'NaF', 'PET', and 'plaque', and all studies with data regarding the degree of microcalcification, as measured by 18F-NaF uptake in symptomatic and asymptomatic atherosclerotic plaques, were included. Analysis involved calculating mean differences between uptake values and comparison using a random-effects model. A total of 16 articles, involving 423 participants, were included in the meta-analysis (10 carotid artery studies, five coronary artery studies, and one in peripheral vascular disease). Comparing 18F-NaF uptake in symptomatic versus asymptomatic atherosclerotic plaques, a mean difference of 0.43 (95% CI 0.29 to 0.57; p < 0.0001, I2 = 65%) was noted in studies comparing symptomatic and asymptomatic plaques in the same participant, with a significant difference in effect based on arterial territory studied (χ2 = 12.68, p = 0.0018). In studies of participants with and without symptomatic disease, there was no significant difference between symptomatic and asymptomatic plaques (mean difference 0.27, 95% CI -0.26 to 0.80, p = 0.28, I2 = 85%). PET imaging using 18F-NaF can detect differences in microcalcification between symptomatic and asymptomatic atherosclerotic plaques within, but not between, individuals, and thus, is a marker of symptomatic disease. The standardization of 18F-NaF PET imaging protocols, and its future use as a risk stratification tool or outcome measure, requires further study. (PROSPERO Registration ID: CRD42023451363).

Mechanism of Enhanced Fluoride Adsorption Using Amino-Functionalized Aluminum-Based Metal–Organic Frameworks

Due to the increasing fluoride concentrations in water bodies, significant environmental concerns have arisen. This study focuses on aluminum-based materials with a high affinity for fluorine, specifically enhancing metal–organic frameworks (MOFs) with amino groups to improve their adsorption and defluorination performance. We systematically investigate the factors influencing and mechanisms governing the adsorption and defluorination behavior of amino-functionalized aluminum-based MOF materials in aqueous environments. An SEM, XRD, and FT-IR characterization confirms the successful preparation of NH2-MIL-101 (Al). In a 10 mg/L fluoride ion solution at pH 7.0, fluoride ion removal efficiency increases with the dosage of NH2-MIL-101 (Al), although the marginal improvement decreases beyond 0.015 g/L. Under identical conditions, the fluoride adsorption capacity of NH2-MIL-101 (Al) is seven times greater than that of NH2-MIL-101 (Fe). NH2-MIL-101 (Al) demonstrates effective fluoride ion adsorption across a broad pH range, with superior fluoride uptake in acidic conditions. At a fluoride ion concentration of 7 mg/L, with 0.015 g of NH2-MIL-101 (Al) at pH 3.0, adsorption equilibrium is achieved within 60 min, with a capacity of 31.2 mg/g. An analysis using adsorption isotherm models reveals that the fluoride ion adsorption on NH2-MIL-101 (Al) follows a monolayer adsorption model, while kinetic studies indicate that the predominant adsorption mechanism is chemical adsorption. This research provides a scientific basis for the advanced treatment of fluoride-containing wastewater, offering significant theoretical and practical contributions.

Clinical and experimental evaluation of the efficacy of a new remineralizing gel in the comprehensive treatment of caries and non-carious lesions in elderly patients

Relevance. Remineralization therapy and fluoridation are well-established methods for preventing hard tissue diseases of the teeth across various age groups. Given the unique composition and structure of teeth in the elderly, there is a need for specialized remineralization and fluoridation agents tailored to this demographic.Materials and methods. A new remineralizing gel, formulated from a mixture of tetra- and dimethylglycerolates of silicon, was developed specifically for the prevention and treatment of hard tissue diseases in elderly patients. The clinical efficacy of this gel was assessed using enamel resistance test (ERT) values and electroodontodiagnostics (EOD) both before and after treatment. Laboratory analyses included the evaluation of phosphorus, calcium, and the Ca/P ratio in saliva using Mindray reagents. An experimental study on tooth sections treated with various remineralizing agents was conducted using a Tescan MIRA LMS scanning electron microscope, equipped with an Oxford Instruments EDS X-max80 attachment, to determine the chemical composition and surface characteristics.Results. The clinical application of the new gel resulted in significant reductions in ERT and EOD values, indicating its effectiveness. An increase in the calcium-phosphorus ratio in saliva further demonstrated the gel’s remineralizing properties. The experimental study revealed the highest fluoride uptake in tooth sections treated with the new gel, confirming its penetration into the hard tissues of the teeth.Conclusion. The new gel, based on a silicon glycerolate mixture, demonstrated superior efficacy in elderly patients compared to other remineralizing agents, which is attributed to the high conductive properties of its base.

Impact of Calcium Lactate Pretreatment on Enamel Fluoride Uptake: A Comparative In Vitro Study of Different Fluoride Types and Concentrations.

(1) Background: This study aimed to establish the effect of calcium lactate enamel pretreatment related to different fluoride types and concentrations on the enamel uptake of alkali-soluble fluorides. (2) Materials: In a blind and randomized in vitro study, a total of 60 teeth are used. The first 30 teeth were cut and randomly allocated into one of the following treatments: (A) calcium lactate pretreatment followed by three different fluoride solutions; (B) the "Fluoride only" group, with slabs treated with three different fluoride solutions; (C) the "Calcium only" group, with slabs treated with calcium lactate solution; (D) slabs treated with deionized water (negative control group). The next 30 teeth underwent all the above described group procedures but were treated with lower fluoride concentrations. Fluoride was extracted from enamel using 1 M KOH solution and analyzed using a fluoride ion-specific electrode. (3) Results: The findings revealed that slabs treated with NaF following calcium lactate pretreatment exhibited significantly greater enamel uptake of alkali-soluble fluoride compared to other substrates. This significant effect was not observed at lower fluoride concentrations. (4) Conclusion: The study demonstrates that pretreatment with calcium lactate followed by treatment with NaF at 226 ppm F significantly enhances the uptake of alkali-soluble fluoride in enamel compared to other fluoride types.

Is 18F-fluoride PET/CT an Accurate Tool to Diagnose Loosening After Total Joint Arthroplasty?

Several studies using positron emission tomography (PET) show highly elevated periprosthetic bone uptake of fluorine-18 sodium fluoride (18F-fluoride), suggestive of implant loosening after arthroplasty. Focus so far has been on qualitative but not on quantitative assessment. There is also a lack of intraoperative confirmation of preoperative 18F-fluoride PET findings. Although the method seems to have acceptable accuracy and high sensitivity, an attempt to improve the specificity and an overall validation of the method appear warranted. (1) Is there a difference in 18F-fluoride uptake around loose versus well-fixed THA and TKA components? (2) Can 18F-fluoride uptake measures provide a threshold that differentiates loose from well-fixed implants undergoing revision for a variety of septic and aseptic indications? (3) In a population restricted to THA and TKA undergoing revision for aseptic indications, can measurement of 18F-fluoride uptake still distinguish loose from well-fixed components? (4) What is the interrater reliability of measuring 18F-fluoride uptake? This was a retrospective assessment of a diagnostic test, 18F-fluoride PET/CT, which was performed prior to revision surgery. We included 63 patients with 31 THAs and 32 TKAs. Sixty-five percent of patients were female, and the mean age at 18F-fluoride PET/CT was 66 years. The THA had different modes of fixation (cemented, cementless, and hybrid; 45%, 32%, and 23%, respectively), whereas all TKAs were cemented. Imaging was conducted using routine protocols 1 hour after tracer injection. The interobserver reproducibility was analyzed using Spearman rank correlations and Bland-Altman analyses. Two independent observers were trained separately by a nuclear physician to measure maximal periprosthetic standardized uptake values (SUVmax) for each arthroplasty component (n = 126). Findings at surgery (whether the components were well fixed or loose, as well as the presence or absence of infection) were used as a reference. Presence of periprosthetic joint infection was retrospectively determined based on the criteria suggested by the European Bone and Joint Infection Society (EBJIS): clinical features in combination with blood analysis, synovial fluid cytologic analysis, and microbiology test results. Receiver operating characteristic (ROC) curves were plotted to assess the area under the curve (AUC) for each investigated component separately, indicating suitable SUVmax thresholds that differentiate loose from well-fixed components. After excluding patients with confirmed or suspected PJI per the EBJIS criteria (n = 12), the above analysis was repeated for the remaining patients with aseptic loosening (n = 51). We found higher 18F-fluoride uptake around loose versus well-fixed components in all but femoral TKA components (median [range] SUVmax for well-fixed versus loose THA cups 10 [7 to 30] versus 22 [6 to 64], difference of medians 12; p = 0.003; well-fixed versus loose TKA femoral components 14 [4 to 41] versus 19 [9 to 42], difference of medians 5; p = 0.38). We identified favorable ROC curves for all investigated components except femoral TKA components (THA cups AUC 0.81 [best threshold 13.9]; THA femoral stems AUC 0.9 [best threshold 17.3]; femoral TKA components AUC 0.6 [best threshold 14.3]; tibial TKA components AUC 0.83 [best threshold 15.8]). 18F-fluoride was even more accurate at diagnosing loosening when we limited the population to those patients believed not to have prosthetic joint infection (THA cups AUC 0.87 [best threshold 14.2]; THA femoral stems AUC 0.93 [best threshold 15.0]; femoral TKA components AUC 0.65 [best threshold 15.8]; tibial TKA components AUC 0.86 [best threshold 14.7]). We found strong interrater correlation when assessing SUVmax values, with Spearman ρ values ranging from 0.96 to 0.99 and Bland-Altman plots indicating excellent agreement between the two independent observers. Measuring SUVmax after 18F-fluoride PET/CT is a useful adjunct in the diagnostic evaluation for suspected implant loosening after THA and TKA. The method appears to be both accurate and reliable in diagnosing implant loosening for all components except femoral TKA components. In a real-world mixed population with both low-grade infection and aseptic loosening, the method seems to be fairly easy to learn and helpful to subspecialized arthroplasty clinicians. When infection can be ruled out, the method probably performs even better. Further prospective studies are warranted to explore the reason why femoral TKA component loosening was more difficult to ascertain using this novel technique. Level III, diagnostic study.

Aortic Uptake of 18F-NaF and 18F-FDG and Calcification Predict the Development of Abdominal Aortic Aneurysms and Is Attenuated by Drug Therapy.

Abdominal aortic aneurysms expand over time and increase the risk of fatal ruptures. To predict expansion, the isolated assessment of 18F-fluorodeoxyglucose (FDG) and sodium fluoride (NaF) uptake or calcification volume in aneurysms has been investigated with variability in results. We systematically evaluated whether 18F-FDG and 18F-NaF uptake was predictive of abdominal aortic aneurysm expansion. Seventy-four male Sprague-Dawley rat abdominal aortic aneurysm models were imaged using positron emission tomography-computed tomography with 18F-FDG and 18F-NaF at 1, 2, 4, 6, and 8 weeks after CaCl2 or saline stimulation. In the 1-week cohort (n=25), the correlation between 18F-FDG or 18F-NaF uptake and pathological markers was investigated. In the time course cohort (n=49), animals received either atorvastatin, losartan, aldactone, or risedronate to assess the effect of these drugs, and the relationship between aortic size and sequential 18F-FDG and 18F-NaF uptake or calcification volume was examined. In the 1-week cohort, the maximum standard unit value of 18F-FDG and 18F-NaF uptake correlated with CD68- (r=0.82; P=0.001) and von Kossa staining-positive areas (r=0.89; P<0.001), respectively. In the time course cohort, 18F-FDG and 18F-NaF uptake changed in a time-dependent manner and drugs attenuated this uptake. Specifically, 18F-FDG showed high uptake at weeks 1 and 2, whereas a high 18F-NaF uptake was noted throughout the study period. Atorvastatin and risedronate showed a decreased and increased aortic size, respectively. The final aortic area correlated well with 18F-FDG and 18F-NaF uptake and calcification volume, especially at 1 and 2 weeks (18F-NaF [1 week]: r=0.61, 18F-FDG [2 weeks]: r=0.51, calcification volume [1 week]: r=0.59; P<0.001). Multiple linear regression analysis showed that the combination of these factors predicted the final aortic size, with 18F-NaF uptake at 1 week being the strongest predictor. The uptake of 18F-NaF and 18F-FDG and the calcification volume at appropriate times correlated with the development of abdominal aortic aneurysms, with 18F-NaF uptake being the strongest predictor.

Removal of arsenic and fluoride ions from aqueous solutions using electronic waste-derived adsorbent

Printed Circuit Boards are the fundamental component of almost every electronic device with usage intensifying at an average rate of 8.7 %. However, this leads to a generation of 45 million tons of electronic waste (E-waste) annually posing significant and concerning environmental risks. Recycling these waste printed circuit boards (PCBs) is vital, in terms of environmental pollution, prevention and resource recycling. Activating these non-metallic fractions of the printed circuit boards results in the development of unique textural properties and functionalities which resemble aluminosilicates; confirmed by FTIR, XRD, XPS, XRF, and TGA and could potentially be applied for the uptake of Fluoride and Arsenate. In this study, Activated Non-metallic fraction of the Printed Circuit Boards (A-NMP) was used to investigate various physio-chemical parameters, including contact time, pH, adsorbent dose, and initial concentration to optimize the reaction conditions for the uptake of F− and As(V) from aqueous solutions and, compared its adsorption capacity with other natural and synthetic aluminosilicate. The maximum adsorption capacity comes out to be 4.33 mg g−1 and 4.65 μg g−1 for F− and As(V) and best fit to Langmuir and Freundlich adsorption isotherms, respectively. Kinetic modelling reveals that the adsorption of F− follows pseudo-first-order kinetics whereas, As(V) follows pseudo-second-order kinetics. Moreover, Intra-particle diffusion revealed a chemisorption-controlled process for both the adsorbates. Furthermore, in a binary component system the F− and As(V) showed the maximum percentage removal of 92 % and 76 %, respectively at pH 5, and best fit to Langmuir adsorption isotherm.

Cerium-based metal-organic-frameworks with ligand tuning of the microstructures for fluoride adsorption: linear and nonlinear kinetic and isotherm adsorption models.

We present the synthesis and characterisation of three Ce-based metal-organic frameworks (Ce-MOFs) using fumaric acid (Fu), terephthalic acid (BDC), and trimesic acid (H3BTC) as linkers. The use of different linkers influenced the size of the MOF particles, surface area, crystallinity, and microporous structure. The successful implementation of Ce-Fu, Ce-BDC, and Ce-H3BTC MOFs for fluoride ion removal from wastewater was carried out, in which Ce-Fu MOFs exhibited a maximum adsorption capacity (AC) of 64.2 mg g-1. The study also reveals that the use of ultrasound as a mediator for adsorption study over conventional method gives rapid adsorption rate, in which 85% of the fluoride uptake took place just in 10 min and achieved maximum AC in 30 min. The kinetics data were most accurately explained by the pseudo-second-order model (PSO). The existence of co-ions such as NO3-, Cl-, HCO3-, SO42-, Br-, CO32-, and PO43- has a substantial effect on fluoride removal. The mechanism between the fluoride ions and the MOF surface took place via the electrostatic force and the ion exchange process, confirmed using X-ray photoelectron spectroscopy (XPS) and delsa nano. The material is sustained its relatively higher F- ions removal efficiency up to the five cycles. This research might help in the development of novel microporous Ce-based MOFs since it possesses a highly stable crystalline structure in water, suggesting a promising role in aqueous applications.

Deep Intergranular Fluoride Attack by High-Temperature Corrosion on Alloy 625 by LiF in Air at 600 °C

In most chemical and high-temperature processes, metals are exposed to temperature gradients which, in turn, affect the extent of corrosion phenomena. In this study, a long, continuous strip of alloy 625 was exposed to lithium fluoride in a temperature range of 50–600 °C, air environment. The hottest section of this strip was analyzed as a coupon and compared with two other coupons which were exposed isothermally. One of the isothermal exposures was carried out in a tube furnace, and the other one was in a vertical furnace. Oxygen had three different kinds of access to these three coupons, which, in turn, affected the corrosion process. In order to limit the access of oxygen, a long column of lithium fluoride was used in a vertical furnace. The results of the isothermal exposure showed that more access of oxygen in a horizontal tube furnace facilitated the fluoride ingress to a great extent. However, a long sample exposed to a temperature gradient suffered more corrosion attack than the isothermal coupon, under the same LiF load in the vertical furnace. This was associated with the reduction of oxygen at a larger cathode area reaching into colder regions in Inconel 625 strip. Increased oxygen reduction also increases the efficiency of an inner anode at the hottest section, causing the observed rapid intergranular fluoride uptake. The study proposes a mechanism explaining these observations.

Synthesis of calcium-based nanofertilizer and its efficacy towards reduction of oxidative stress and fluoride uptake in rice (Oryza sativa L.)

The phytotoxicity of fluoride and its build-up in agricultural plants and subsequently the entry into the food chain is a serious threat to human health. The present study highlighted the green synthesis of calcium oxide nanoparticles (CaO NPs) and characterization using UV-Vis spectrophotometer, TEM, SEM, EDX, XRD, and FTIR. Further, synthesized CaO NPs (0, 10, and 50 mg/L) were applied on fluoride-stressed (10 mg/L) rice seedlings to check its possible ameliorative effects towards growth and fluoride accumulation in different parts of rice seedlings. Characterization revealed that nanoparticles were crystalline (46.72 %) and spherical in shape, with an average diameter of 20–25 nm. Results of the seedling growth analysis revealed that CaO NPs inhibited the translocation of fluoride in rice plants, which in turn decreased the phytotoxicity caused by fluoride, including lipid peroxidation and chlorosis, and enhanced the overall growth of seedlings. The co-exposure of CaO NPs with fluoride also showed a reduction in the fluoride-induced oxidative stress, as demonstrated by lower MDA, O2•- contents, and activity of antioxidant enzymes (CAT, SOD, and POD) as compared to fluoride treatment alone. The application of CaO NPs also restored potassium content in seedlings grown under fluoride stress. Furthermore, the highest reduction of fluoride accumulation by 65 and 76 % in roots and shoots was recorded at 50 mg/L of CaO NPs treatment, respectively. Therefore, the present study clearly indicated the ameliorative potential of CaO NPs towards fluoride stress in rice. However, a field study is needed to establish the social acceptance of this valuable nanofertilizer in fluoride-contaminated areas.

Performance of simplified methods for quantification of [18F]NaF uptake in fibrodysplasia ossificans progressiva.

Fibrodysplasia Ossificans Progressiva (FOP) is a rare, genetic disease in which heterotopic bone is formed in muscles, tendons and ligaments throughout the body. Disease progression is variable over time and between individuals. 18F-fluoride uptake in newly formed bone can be evaluated using [18F]NaF (i.e., sodiumfluoride) PET/CT, identifying active areas of bone formation in FOP. The purpose of this study was to assess the performance of various semi-quantitative methods with full kinetic analysis. Seven patients (age range: 20-31 years) with FOP underwent dynamic [18F]NaF scans at baseline and after one year. [18F]NaF uptake was measured in aorta descendens, vertebrae, heterotopic bone lesions and metabolically active regions on PET, and quantified using nonlinear regression (NLR) analysis together with standardized uptake value (SUV) and target-to-blood ratio (TBR). SUV was on measured the 40-45 min frame of the dynamic sequence (SUV40-45) and on the subsequent static sweep (SUVStatic). Correlations between and SUV40-45 and NLR-derived Ki were comparable when normalized to body weight (r = 0.81, 95% CI 0.64-0.90), lean body mass (r = 0.79, 95% CI 0.61-0.89) and body surface area (r = 0.84, 95% CI 0.70-0.92). Correlation between TBR40-45 and NLR-derived Ki (r = 0.92, 95% CI 0.85-0.96) was higher than for SUV40-45. Correlation between TBR40-45 and NLR-derived Ki was similar at baseline and after one year (r = 0.93 and 0.94). The change in TBR40-45 between baseline measurement and after one year correlated best with the change in NLR-derived Ki in the PET-active lesions (r = 0.87). The present data supports the use of TBR for assessing fluoride uptake in PET-active lesions in FOP. Sub-study of the Lumina-1 trial (clinicaltrials.gov, NCT03188666, registered 13-06-2017).

Performance evaluation and mechanism of Al2O3/TiO2 sorbents for fluoride remediation in groundwater

Excessive fluoride levels in drinking water are problematic in several countries, particularly those which are relatively poor. Thus, there is a need to create cost effective sorbents which can easily be applied to make the water safe to use. Therefore, this study focussed on Al2O3/TiO2 sorbents which appear to address issues with commercially available alumina such as aluminium dissolution. Adjusting the alumina/titania ratio significantly influenced not only the fluoride uptake capacity but also the uptake of a wide range of contaminants found in groundwater. The exchange kinetics were relatively fast regardless of mixed oxide composition with equilibrium obtained within 6 h. Equilibrium isotherms were unfavourable for fluoride removal where titania compositions were dominant. In contrast, favourable isotherms were noted when alumina was the dominant oxide present. Barium, calcium, strontium, boron, iron, manganese, zinc, potassium, lithium, and silica were all substantially removed by varying the alumina/silica ratio in the sorbent. This behaviour may be valuable for broader remediation of dissolved species in groundwater (not just fluoride). Based upon the tests data a 70% Al2O3 – 30% TiO2 material was recommended to be the preferred composition for comprehensive treatment of groundwater. The sorbents appeared to comprise of alumina and titania with surface areas between 129 and 255 m2/g. There was no evidence for new oxide phases nor for a relationship between surface area and performance. Mechanistically both ion exchange and surface complexation may occur when treating groundwater.

Effect of training on bone quality in rats with insulin resistance induce by fluoride consumption.

When large amounts of Fluoride are consumed produces insulin resistance, but exercise can reverse insulin resistance in rats, because of a high fluoride uptake by bone tissue. However, bone quality has not been studied in those experiments. Therefore, the aim of this work was to evaluate bone quality in rats treated with fluoride when performing exercise. Sprague-Dawley rats were divided into 3 groups (n=6 per group): Control (drinking water without fluoride), Fluoride (drinking water with fluoride 15 mg/L for 30 days) and Exercise (daily running on a treadmill and drinking water with fluoride 15 mg/L for 30 days). Then, bone mineral density, mechanical and histological properties and bone fluoride level were measured. No effect of treatment on any bone parameters were observed. These results indicate that exercise normalizes glucose metabolism in insulin-resistant rats by bone fluoride uptake; however, this increase in bone fluoride does not manifest in bone deterioration.

Comprehensive batch studies on removal of fluoride from aqueous solution by acid and alkali-activated adsorbents prepared from Dal lake weeds: Mechanism, Kinetics and Thermodynamics

An efficient and economical way of eliminating fluoride from water is being investigated by employing the buoyant aquatic plant (Dal weed). Two post-pyrolysis chemical activation alteration techniques were implemented: acidic activation by employing sulfuric acid (H-activation) and alkaline activation using sodium hydroxide (OH-activation). The batch kinetic studies have been carried out considering varying starting fluoride levels such as 2–10 mg/L. The impact of diverse procedural factors, including dosage of Dal weed, starting fluoride level, pH and contact duration was observed to determine their influence on fluoride adsorption kinetics. Based on analyzed exploratory results, removal efficacy of 63% for the OH-activated carbon and 83% for H-activated carbon was achieved at commencing fluoride level of 10 mg/L, adsorbent dosage of 0.8 g, at 25 °C after 120 min. The maximal fluoride uptake capacity for H-activated carbon was observed to be 78.158 mg/g. Kinetic investigations showed that the Freundlich isotherm model provided a satisfactory match with an R2 value of 0.99. The reaction order nature adhered to kinetics resembling pseudo second order. Thermodynamic investigation revealed endothermic sorption, with negative ΔG indicating spontaneous fluoride uptake. In comparison, the positive number for ΔS suggested random behavior at the contact involving the adsorbent and adsorbate. The investigations into the regeneration capabilities of the adsorbent material revealed that even after undergoing for five consecutive cycles of adsorption and regeneration, the adsorbent exhibited an uptake potential of 45%. The presence of competing ions in the solution negatively impacted defluoridation efficacy, with the influence following the order of HCO3−< NO3−< Cl−< SO42−< PO43−.

Facile construction of graphene oxide and iron organic frameworks decorated biopolymeric hybrid materials for fluoride uptake from water

The widespread excess level of fluoride in water causes a possible risk to human health. Herein, graphene oxide (GO) and iron-type metal–organic frameworks namely iron-benzene-1,4-dicarboxylate (Fe-BDC) supported material namely GO/Fe-BDC was employed to remove fluoride in water. Because of powder form, GO/Fe-BDC creates pressure drop during filtration. To overcome such troubles and improve fluoride adsorption capacity, GO/Fe-BDC integrated alginate (Alg) and chitosan (CS) biopolymer-based hybrid material namely GO/Fe-BDC/Alg-CS beads was developed for fluoride removal. Defluoridation properties of GO/Fe-BDC and GO/Fe-BDC/Alg-CS beads were evaluated under numerous influencing conditions namely pH, contact time, variable fluoride concentration, co-ions, dosage and temperature studies. The GO/Fe-BDC and GO/Fe-BDC/Alg-CS beads were revealed finer fluoride adsorption ability and also had high fluoride selectivity in complexed atmosphere with several co-ions. The element composition, crystalline nature and material morphology of GO/Fe-BDC and GO/Fe-BDC/Alg-CS beads were characterized using SEM, XRD, FTIR and EDAX analysis. The order and nature of defluoridation was examined with kinetics, thermodynamic and isotherm analysis. The highest r values and lowest sd values exhibit that Langmuir adsorption isotherm and pseudo-second-order (PSO) models were consider as best fit models for fluoride adsorption process onto GO/Fe-BDC and GO/Fe-BDC/Alg-CS beads. The thermodynamic results illustrate that fluoride adsorption was spontaneous, chemical adsorption with endothermic nature . Electrostatic interaction and complexation were found as the primary defluoridation mechanism of GO/Fe-BDC and GO/Fe-BDC/Alg-CS beads. The renewal and field investigations of GO/Fe-BDC and GO/Fe-BDC/Alg-CS beads were explored to check their regeneration ability and field suitability nature.

Stain removal, abrasion and anticaries properties of a novel low abrasion dentifrice containing micro-fibrillated cellulose: in vitro assessments

ObjectivesThis laboratory study assessed the performance of a novel fluoride dentifrice containing micro-fibrillated cellulose (MFC) and entrapped silica. MethodsRemoval of extrinsic stains was assessed using the pellicle cleaning ratio (PCR) method, and radioactive dentin abrasivity (RDA) was measured, to calculate a cleaning efficiency index (CEI). Fluoride efficacy was evaluated using widely used remineralization and fluoride uptake methods. The test product (Protegera™) was compared to common dentifrices (Crest - Cavity Protection™ and ProHealth™, Sensodyne Pronamel™, Arm & Hammer™ Advanced Whitening, Crest ProHealth™, and Colgate Optic White™). ResultsThe PCR for the MFC dentifrice (141) was comparable to three known marketed stain-removing dentifrices (Arm & Hammer™ Advanced Whitening, Crest ProHealth™, and Colgate Optic White™) but it had a significantly lower RDA (88 ± 6) than 5 other products. This gave it the highest CEI of the tested products (2.0). In a 10-day pH cycling study, the fluoride efficacy of the MFC product was comparable to Sensodyne Pronamel and Crest Cavity Protection. The MFC dentifrice was superior for promoting fluoride uptake into incipient enamel lesions compared to the USP reference dentifrice. ConclusionThe MFC dentifrice has low abrasion, but despite this, it is highly effective in removing stained pellicle. It also is an efficacious fluoride source when compared to relevant commercially available fluoride dentifrices with high dentin abrasivity. Clinical significanceThe addition of micro-fibrillated cellulose to a fluoride dentifrice gives a low abrasive product that can effectively remove external stains, and serve as an effective fluoride source. This combination of benefits seems well suited to enamel protection and caries prevention.