Fluorite (CaF2) leaching and weathering (30 days) were conducted to measure fluoride dissolution in semiarid endemic soil and controlled synthetic solutions, and determining the main chemical species involved in these processes via atomic force microscopy (AFM), X-ray diffraction (XRD) and Scanning electron microscopy (SEM-EDS). Ecological health response in this system was assessed exposing Allium cepa bulbs to 10, 50, 100, 450, 550 and 950 mg CaF2 kg-1 soil to determine genotoxic damage, protein and systemic fluorine concentrations. Results indicated 3 cycles of passive-active fluorite dissolution enabling fluoride concentrations up to 164 mg L-1 under endemic conditions; however, highest fluoride dissolution was 780 mg L-1 for synthetic sulfates solution. Cyclic behavior was associated with the formation of ultrafine-sized calcite (CaCO3)-like compounds. Fluorine concentrations ranged from 5 to 300 mg kg-1 in vegetable tissue. The electrophoretic profiles revealed changes in the protein expression after 7, 15 and 25 days of exposure. Genotoxic damage rate was 50, 82 and 42% for these exposures (950 mg CaF2 kg-1 soil). The dose-response curves of the normalized total protein content revealed the kinetics vegetable health damage rates for only 7 and 25 days. This behavior was best adjusted for only 7 days. These findings exhibited characteristics for initial damage and adaptation-recovery stage after 15 days. Environmental implications of these findings were further discussed.

Fluoride, a highly phytotoxic and nonessential element in higher concentrations is a major concern in decreasing wheat production. In the present study, we examined the ability of silicon, a semi-essential element which helps to mitigate the detrimental effects of various environmental stresses in overcoming fluoride-mediated toxicity in wheat cultivars. The seeds of two wheat cultivars, tolerant (Raj 4120) and susceptible (Raj 4238), were grown in soil supplemented with NaF (0, 400, and 500 mg kg-1) and then supplied with silicon (0, 200, and 300 mg kg-1) as Na2SiO3 at 10th days of germination with 160 mu mol quanta m-2 s-1 of photon density, 16-h photoperiod, and 55-60% relative humidity at 25 +/- 2 degrees C. The fluoride stress led to oxidative damage in roots, as evidenced by the significant elevation in MDA and H2O2 content in both wheat cultivars and decreased major components of the suberin and cesA4 gene expression in roots, which together can negatively impact the rigidity and strength of the cell wall. Conversely, the application of silicon had a beneficial effect in both wheat cultivars with and without fluoride stress. Silicon decreased the MDA and H2O2 content levels and increased the antioxidant defence system. Interestingly, Si was able to partially reverse F stress in both the wheat cultivars by increasing suberin deposition on the endodermis and promoting secondary cell wall synthesis gene expression in roots. The present study concluded that soil application of silicon can be a useful approach in protecting wheat from fluoride toxicity.

Fluoride, a naturally occurring element found in water, soil, food, and atmospheric precipitation, can lead to fluorosis and various health issues when consumed excessively. However, the mechanism of fluorosis is still under investigation. This study utilizes Caenorhabditis elegans as a model organism to investigate the effects of fluoride exposure on biological systems and to explore the mechanisms by which curcumin mitigates fluoride- induced toxicity. Three groups were established: a blank control, a sodium fluoride (NaF) exposure group (concentration 5 mmol/L), and a curcumin intervention group (concentration 25 mu mol/L). Physiological parameters, lipofuscin levels, intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential, and mitochondrial copy numbers were measured to assess the effects of fluoride toxicity and curcumin protection. RNA-seq and qRT-PCR were utilized to investigate the molecular mechanisms underlying fluoride- induced damage and curcumin's mitigating effects. Results indicated that fluoride-exposed nematodes displayed physiological abnormalities, increased ROS production, higher lipofuscin levels, altered mitochondrial membrane potential and mitochondrial copy number, and activated MAPK signaling pathway genes. Curcumin exhibited protective effects on these parameters, suggesting its potential in preventing fluoride-induced harm by modulating oxidative stress and preserving mitochondrial function. This research enhances our understanding of the mechanisms of fluoride toxicity and highlights the potential benefits of curcumin.

In recent years, the effects of fluoride (F) pollution in numerous ecosystems such as groundwater, soil, etc. Have become a major issue worldwide. This increase in F pollution is a direct consequence of the unbridled use of fertilizers in agricultural and several other human activities that require immediate and appropriate action. Therefore, this manuscript reveals important findings on the efficacy of bacteria isolated from agricultural fields in central Chhattisgarh in manifesting resistance to F and in reversing the F-induced oxidative damage in susceptible Oryza sativa L, (Var. MTU1010). Chronic exposure of Oryza sativa L. to sodium fluoride (NaF) (50 mg L- 1) severely impeded growth and various physiological parameters such as germination percentage, biomass and root and shoot length and stimulated the formation of reactive oxygen species (ROS), which enhanced electrolyte leakage and formation of cytotoxic products like malondialdehyde. To this end, potential bacterial strains, namely MT2A, MT3A, MT4A, and Du3A were isolated, screened for various plant growth promoting (PGP) traits and used to explore their efficiency to mitigate F toxicity in Oryza sativa L. in vivo. The seedlings inoculated with the bacterial strains showed significant development as evidenced by an increase in root and shoot length, biomass and chlorophyll content. Additionally, inoculation of these strains in combination with F stress significantly decreased oxidative stress by increasing the expression of protective genes encoding antioxidant enzymes and boosted agronomic traits remarkably. Overall, the manuscript demonstrates the pivotal role played by the isolated bacteria in abating ill effects of F in the Oryza sativa L. seedlings and proves their potential as protective bioagents against F stress.

Frictional heat generated by mechanisms that take service on celestial bodies such as the moon does not dissipate easily owing to the vacuum environment and the low thermal conductivity of celestial soil. Consequently, the temperature of these mechanisms increases significantly. The wear resistance of liquid lubricants at high temperatures degenerates rapidly because the oil film thins out and the oil decomposes. Polytetrafluoroethylene (PTFE) and the soap fiber thickeners of lubricants are susceptible to phase transitions and agglomeration. The wear resistance and thermal stability of lubricants must be improved for mechanisms operating on celestial bodies. The lubricating properties at high temperatures and the thermal stability of fluorinated graphite are excellent. The wear resistance of liquid lubricants for space mechanisms can be improved using fluorinated graphite. In this study, fluorinated-graphite-modified perfluoropolyether (PFPE) greases are prepared using fluorinated graphite with different fluorine-to-carbon ratios and particle sizes, PTFE powders, and D-type PFPE base oil. The thermal behaviors of the materials are characterized using thermogravimetry and differential scanning calorimetry. Electron spectroscopy and X-ray diffraction are used to determine the fluorine-to-carbon ratios and the structures of three types of fluorinated graphite. The effects of different fluorinated graphites on the rheological and tribological properties of the greases are evaluated at 25 degrees C in atmospheric and vacuum environments, as well as at 200 degrees C in a high-temperature vacuum environment. The results show that the decomposition temperature of the three types of fluorinated graphites are higher than 595 degrees C , whereas that of the D-type PFPE base oil is 450 degrees C . The fluorine-to-carbon ratios of C2FJ1002, CFT10, and CF500 fluorinated graphites are 0.92, 0.88, and 1.04, respectively. Among them, the fluorine-to-carbon ratio of the nanoscale fluorinated graphite, CFT10, is the lowest. The (001) reflection of this nanofluorinated graphite is higher than the others; therefore, its (CF)n is greater than those of the others. The nanoscale fluorinated graphite exhibits the most significant thickening effect on grease at room temperature under low shear owing to its larger specific surface area. However, under high-shear and high-temperature conditions, the thickening effects of the three types of fluorinated graphites are almost uniform At high temperatures, the increased interlayer spacing of fluorinated graphite results in more PFPE oil molecules being absorbed, thus resulting in an increase in the shear viscosity of the grease at a shear rate of 10-15 s(-1). The wear-scar diameter of the grease modified by the abovementioned three types of fluorinated graphites under a 25 degrees C vacuum environment decreases by 7.7%, 11.7%, and 13.2%, respectively. The CF500 fluorinated graphite with the highest fluorine-to-carbon ratio demonstrates the best wear resistance in grease. Additionally, it exhibits a decreasing worn function under a 200 degrees C vacuum environment. The C 1s core-level spectra of the wear scars lubricated by the PFPE grease suggest the formation of amorphous carbon on the wear scar due to the degradation of PFPE. However, the C 1s core-level spectra of the wear scars lubricated with grease, which are modified by the CF500 fluorinated graphite, do not suggest the formation of amorphous carbon. The CF500 fluorinated graphite can shield the tribological surface and mitigate the degradation of the PFPE base oil. The higher the fluorine content, the more prominent is the reduction in wear of the PFPE grease in both vacuum and high-temperature vacuum environments. This is primarily attributed to its higher thermal stability and adsorption capacity for PFPE oil molecules, which reduces the chain breakage and carbonization of PFPE. However, reducing the particle size does not significantly reduce wear.

The impact of fluorine on plants remains poorly understood. We examined duckweed growth in extracts of soil contaminated with fluorine leached from chicken manure. Additionally, fluorine levels were analyzed in fresh manure, outdoor-stored manure, and soil samples at varying distances from the manure pile. Fresh manure contained 37-48 mg F- x kg(-1), while soil extracts contained 2.1 to 4.9 mg F- x kg(-1). We evaluated the physiological effects of fluorine on duckweed cultured on soil extracts or in 50% Murashige-Skoog (MS) medium supplemented with fluorine concentrations matching those in soil samples (2.1 to 4.9 mg F- x L-1), as well as at 0, 4, and 210 mg x L-1. Duckweed exposed to fluorine displayed similar toxicity symptoms whether in soil extracts or supplemented medium. Fluoride at concentrations of 2.1 to 4.9 mg F- x L-1 reduced the intact chlorophyll content, binding the porphyrin ring at position 3(2) without affecting Mg2+. This reaction resulted in chlorophyll a absorption peak shifted towards shorter wavelengths and formation of a new band of the F--chlorophyll a complex at lambda = 421 nm. Moreover, plants exposed to low concentrations of fluorine exhibited increased activities of aminolevulinic acid dehydratase and chlorophyllase, whereas the activities of both enzymes sharply declined when the fluoride concentration exceeded 4.9 mg x L-1. Consequently, fluorine damages chlorophyll a, disrupts the activity of chlorophyll-metabolizing enzymes, and diminishes the plant growth rate, even when the effects of these disruptions are too subtle to be discerned by the naked human eye.

Fluoride is widely found in groundwater, soil, animal and plant organisms. Excessive fluoride exposure can cause reproductive dysfunction by activating IL -17A signaling pathway. However, the adverse effects of fluoride on male reproductive system and the mechanisms remain elusive. In this study, the wild type and IL -17A knockout C57BL/6J mouse were treated with 24 mg/kg & sdot;bw & sdot;d sodium fluoride and/or 5 mg/kg & sdot;bw & sdot;d riboflavin-5 '-phos- phate sodium for 91 days. Results showed that fluoride caused dental fluorosis, increased the levels of ROS in testicular Leydig cells and GSSG in testicular tissue, and did not affect the iron and serum hepcidin levels in testicular tissue. Riboflavin alleviated above adverse changes, whereas IL -17A does not participate in the oxidative stress -mediated reproductive toxicity of fluoride. Based on this, TM3 cells were used to verify the injury of fluoride on Leydig cells. Results showed that fluoride increased mRNA levels of ferroptosis marker SLC3A2, VDAC3, TFRC, and SLC40A1 and decreased Nrf2 mRNA levels in TM3 cells. The ferroptosis inhibitor Lip -1 and DFO were used to further investigate the relationship between male reproductive toxicity and ferroptosis induced by fluoride. We found that the fluoride -induced decrease in cell viability, increase in xCT, TFRC, and FTH protein expression, and decrease in GPX4 protein expression, can all be rescued by Lip -1 and DFO. Similar results were also observed in the riboflavin treatment group. Moreover, riboflavin mitigated fluoride -induced increases in ROS levels and SLC3A2 protein levels. In all, our work revealed that riboflavin inhibited ferroptosis in testicular Leydig cells and improved the declined male reproductive function caused by fluoride. This study provides new perspectives for revealing new male reproductive toxicity mechanisms and mitigating fluoride toxicity damage.

The purpose of the current study was to evaluate the alleviating effect of silicon (Si) on fluoride (F)-mediated toxicity in wheat cultivars.The photosynthetic efficiency of fully developed wheat leaves was measured by analysing the chlorophyll fluorescence using DUAL-PAM (Heinz Walz, Effeltrich, Germany). The quantitative changes in various biochemical parameters, viz. photosynthetic pigments (chlorophylls and carotenoids), proline, flavonoids, polyphenols, hydrogen peroxide (H2O2) glutamate and ascorbate content in wheat leaves, were monitored by UV-VIS spectrophotometer using established methods. To describe the magnitude of the relationships among biochemical and physiological parameters, the Pearson correlation coefficient was calculated.Our results showed that F stress (400 and 500 mg/kg) affected various photosynthetic parameters (i.e. ETRmax, PPFDsat, 1/2PPFDsat, Delta F/Fm ' sat and 1/2 Delta F/Fm ' sat) and reduced the amount of photosynthetic pigments. Further, increased proline, flavonoids, polyphenols, H2O2, glutamate and ascorbate content in F-stressed wheat plants showed fluoride-induced oxidative damage. In contrast, application of 200 and 300 mg/kg Si to F-toxic soil restored the Chl pigment and photosynthetic parameters and reduced F-induced oxidative damage by concomitant decline in proline, flavonoids, polyphenols, H2O2, glutamate and ascorbate content.By understanding the positive role of Si in plants with and without F stress, the current study has concluded that Si contributed to increased resistance to F stress in wheat cultivars by increased antioxidant metabolites and thereby reduced oxidative damage.