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Insights into the structure and dynamics of large biological systems has been greatly improved by two concurrent NMR approaches: the application of transverse relaxation-optimized spectroscopy (TROSY) techniques in multi-dimensional NMR, especially the methyl-TROSY, and the resurgence of 19 F NMR using trifluoromethyl (CF 3 ) probes. Herein we investigate the feasibility of combining these approaches into a trifluoromethyl-TROSY experiment. Using a CF 3 -labelled parvalbumin, we have evaluated the natural abundance 13 C- 19 F correlation spectra and find no indication of a CF 3 TROSY at high magnetic fields.

Due to the serious symptoms of brittle bones and endocrine disorders, the common disease fluorosis diminishes quality of life. With the aim of developing probes for both laboratory and household fluorosis diagnosis, in this study we rationally designed a novel dual-functional gallic acid-Fe(III) complex-modified upconversion nanoprobe (DF-UCNP) with simultaneous upconversion luminescence (UCL) and photothermal (PT) conversion capacities. The nanoprobe was feasible for UCL fluorine (F - ) detection with a low detection limit of ∼20 nM and a broad linear range of 0-50 μM, as well as UCL fluorosis diagnosis both in vitro and in vivo for lab-use. Furthermore, by utilizing gathered solar irradiation as a PT excitation source and a digital thermometer as a signal reader, the nanoprobe possessed outstanding PT detection capacities for F - with a detection limit of ∼100 nM. Based on this nanoprobe and an accessional self-developed Android application, a household PT kit for fluorosis diagnosis was also constructed. This work provides a new method for rapid laboratory fluorosis diagnosis without a cumbersome determination process as well as household fluorosis diagnosis without requiring specific instruments., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A novel fluorescent sensor CPM for relay detecting Ca 2+ and F - based on coumarin has conveniently synthesized and characterized. The sensor CPM showed highly fluorescence enhancement to Ca 2+ over other metal ions, and the CPM-Ca 2+ complex could selectively recognize F - among other anions. The limits of detection for Ca 2+ and F - were 5.81 × 10 -7  M and 4.28 × 10 -7  M in aqueous solution (DMF/HEPES buffer 1:1 v/v, 10 mM, pH = 7.2), respectively. Their sensing mode had been testified by Job's plots, UV-vis titration, 1 H NMR titrations, ESI-mass, fluorescence and DFT calculations. The fluorescence imaging indicated that CPM was cell-permeable and could be used to effectively detect Ca 2+ and F - within living cells., (Copyright © 2019. Published by Elsevier B.V.)

Ash of Antarctic krill integument (AAKI) was prepared by sintering the integument at 550°C under air atmosphere for 4 hours, and its composition was analyzed by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and electron dispersive spectroscopy (EDS). XRD results showed that the major phase in AAKI was ascribed to apatite. Besides, it was noticed that the (300) peak of AAKI shifted to 33.07°, which was coincident with that of fluorapatite (FA). The FTIR results confirmed the presence of phosphate ions, and the absence of -OH. The EDS results confirmed the presence of Ca, P, O and F elements in the ash sample. The content of FA in the ash was determined to be 50.4%, and the proportion of fluorine in the form of FA to the total fluorine in the integument was 40.5%. Based on the XRD, FTIR and EDS results, it can be concluded that FA was the main form of fluoride in the integument of Antarctic krill.

To achieve the simultaneous removal of NH 4 + -N and NO 3 - -N in F - -containing semiconductor wastewater by coupled S 0 -driven autotrophic denitrification and Anammox process, the effect of variable F - concentration on the Anammox process was investigated by batch experiments. The denitrifying ammonium oxidation (Deamox) reactor was then started-up to explore the feasibility of the coupling of Anammox and sulfur autotrophic denitrification (SADN) for the treatment of semiconductor wastewater. Short-term variation of F - concentration has an obviously effect on the activity of Anammox sludge, but didn't affect the nitrogen conversion rate. The activity of Anammox obviously decreased after long-term operation of the Deamox reactor when influent F - concentrations reached 552 mg/L. The sensitivity of Anammox bacteria to F - concentration is stronger than that of SADN bacteria. Total nitrogen removal efficiency of 98% and total nitrogen removal rate of 4.11 kg/(m 3 ·d) were achieved in the Deamox reactor, when the F - was pre-treated by calcium ions. Moreover, the high-throughput 16S rRNA gene sequence analysis indicated that variation in F - concentrations could influence the structure and functional of microbial communities in the Deamox process. Candidatus Kuenenia, Thiobacillus and Sulfurimonas were main functional bacteria that achieved symbiotic., (Copyright © 2019. Published by Elsevier B.V.)

A varying oxygen environment is known to affect cellular function in disease as well as activity of various therapeutics. For transient structures, whether they are unconstrained therapeutic transplants, migrating cells during tumor metastasis, or cell populations induced by an immunological response, the role of oxygen in their fate and function is known to be pivotal albeit not well understood in vivo. To address such a challenge in the case of generation of a bioartificial pancreas, we have combined fluorine magnetic resonance imaging and unsupervised machine learning to monitor over time the spatial arrangement and the oxygen content of implants encapsulating pancreatic islets that are unconstrained in the intraperitoneal (IP) space of healthy and diabetic mice. Statistically significant trends in the postimplantation temporal dependence of oxygen content between aggregates of 0.5-mm or 1.5-mm alginate microcapsules were identified in vivo by looking at their dispersity as well as arrangement in clusters of different size and estimating oxygen content on a pixel-by-pixel basis from thousands of 2D images. Ultimately, we found that this dependence is stronger for decreased implant capsule size consistent with their tendency to also induce a larger immunological response. Beyond the bioartificial pancreas, this work provides a framework for the simultaneous spatiotemporal tracking and oxygen sensing of other cell populations and biomaterials that change over time to better understand and improve therapeutic design across diverse applications such as cellular transplant therapy, treatments preventing metastatic formation, and modulators for improving immunologic response, for all of which oxygen is a major mechanistic component., Competing Interests: Conflict of interest statement: D.G.A. and R.L. are founding scientists of Sigilon Therapeutics, a biotech company based in Cambridge, MA.

In China, fluoride pollution in soil is severe and poses a serious threat to human health and ecological security. However, how to control fluorine-contaminated soil has not received widespread attention. Here, we summarized fluorine speciation in soil and its main chemical reactions in water-soil system and reviewed the research progress on the remediation of fluorine-contaminated soils. Then, we proposed the focus of future research on fluorine-contaminated soil remediation. The aim of this review was providing the reference for the remediation of fluoride-contaminated soil. There are five forms of fluorine in soils, with the proportion of residual fluorine being over 90%. The reactions of fluorine in the soil solution mainly include precipitation-dissolution, complexation-dissociation, and adsorption-desorption. At present, the remediation technology of fluorine contaminated soil mainly focused on chemo-immobilization, chemical leaching, electrokinetic remediation, and phytoremediation. Clarifying the combined forms of fluorine in soil, screening functional microorga-nisms and plants, developing the combined remediation technology will be the focus of future research. Ultimately, on site fluorine-contaminated soil remediation could be implemented.

In past decades, fluorine exposure of plants and human caused by regional geochemical anomalies of fluorine or environmental pollution has received widespread concerns. Many in-depth researches have been conducted on the geochemical behavior of fluorine in different environmental media, but with disputes and uncertainties. We reviewed the research advances on geochemical behaviors of fluorine in the atmosphere, water and soil, including source, quantity, existence form, migration, transformation, and controlling factors. The observation of correlation between geochemical behaviors of fluorine and plant and human fluoride exposure was also reviewed. Moreover, we proposed that the future research on environmental geochemical behaviors of fluorine should give priority to particular directions.

High concentration of fluorine (F) in agricultural soils has got significant attention considering its impacts on human health, but little information was available about F distribution in farmland soil profiles around phosphorous chemical industry factories. In present study, farmland soil profiles and relevant medium samples were collected from farmlands around a main phosphorous chemical base in southwest China. At 0-100-cm profiles, concentrations of soil total F (Ft, 400.9-1612.0 mg kg -1 ) and water soluble F (Fw, 3.4-26.0 mg kg -1 ) decreased with profile depth in industrial areas. Industrial activities enhanced F concentration in soil mainly at 0-40-cm profiles. No disparity for both Ft and Fw distributions in paddy-dry land rotation field and dry land indicates short-term land utilization could not affect the F distribution in soil profiles. Correlation analysis showed soil organic matter and wind direction were important factors influencing the distribution of F in soil profiles. The shutdown of factory and government control of industrial emissions effectively decreased the ambient air F (Fa) concentrations in industrial areas. In where Fa and dustfall F concentrations were high, high soil Ft, Fw, and crop edible part F concentrations were found.

The basis set convergence of nuclear spin-spin coupling constants (SSCC) calculated at the coupled cluster singles and doubles level has been investigated for ten difficult molecules. Eight of the molecules contain fluorine atoms, and nine contain double or triple bonds. Results obtained using the ccJ-pVXZ, X = D,T,Q,5, hierarchy of basis sets of Benedikt et al. (J Chem Phys 129:064111, 2008), converge rather slowly towards the basis set limit, but fast convergence can be obtained by adding diffuse functions, in particular for couplings across several bonds. The pcJ-n basis sets of Jensen (J Chem Theory Comput 2:1360-1369, 2006) exhibit large contraction errors for one-bond couplings, but in their uncontracted form they perform better than the ccJ-pVXZ basis sets. For multi-bond couplings, however, diffuse functions should be used, and when including these the two hierarchies show similar performance. The ccJ-pVXZ basis sets with diffuse functions included (aug-ccJ-pVXZ) show consistent performance across all types of SSCCs, with the triple-zeta (X = T) basis set yielding sufficiently good results for most purposes. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFASs) are a diverse class of >4700 chemicals used in commercial products and industrial processes. Concerns surrounding PFASs are principally due to their widespread occurrence in humans and the environment and links to adverse health effects. One of the lesser known uses for PFASs is in cosmetic products (CPs) which come into contact with the skin (e.g. hair products, powders, sunblocks, etc.). In the present work, thirty-one CPs from five product categories (cream, foundation, pencil, powder and shaving foam) were analyzed for 39 PFASs by liquid chromatography-tandem mass spectrometry, as well as extractable organic fluorine (EOF) and total fluorine (TF) by combustion ion chromatography (CIC). This multi-platform approach enabled determination of the fraction of fluorine accounted for by known PFASs (i.e. fluorine mass balance). Foundations and powders contained 25 different PFASs with the most frequently detected being perfluorinated carboxylic acids (perfluoroheptanoic acid and perfluorohexanoic acid) and polyfluoroalkyl phosphate esters (PAPs). Σ14PAP concentrations up to 470 μg g-1 were measured in products listing mixtures of PAPs as an ingredient. For all samples, Σ39PFAS concentrations only explained a small fraction of the EOF and TF, pointing to the presence of unknown organic and/or inorganic fluorinated substances, including polymers. While creams, pencil and shaving foams did not contain measurable concentrations of any of the 39 PFASs targeted here, CIC revealed high to moderate TF content. Overall, these data highlight the need for further investigations into the occurrence of PFASs in CPs and their importance with regards to human and environmental exposure.

This study probe the human health risk of fluoride (F), arsenic (As), and selenium (Se) and their daily intake available quantity to human through different sources in different regions of Shaanxi, China. For this purpose, a number of samples, including coal and coal wastes, rocks, soil, and vegetables were collected from south Qinling Mountain stone-like coal (Geo type-I), Binxian-Jurassic (Geo type-II), Hancheng Permo-Carboniferous (Geo type-III), and countryside (Huanglong County) of Shaanxi province. All these samples were analyzed through atomic fluorescence spectroscopy and combustion hydrolysis methods. Results showed that Geo type-I was enriched with As, Se, and F, Geo type-II, III, and the countryside were slightly enriched with As and F and deficient in Se. The average daily intake (ADI) of Se in Geo type-I was 0.005-0.0045, Geo type-II 0.0005-0.0004, Geo type-III 0.0006-0.0005, and countryside 0.0002-0.001 in mg kg -1  day -1 adult-children, respectively, which was lower than the optimum level (0.06-0.075 mg kg -1 day -1 ). ADI of As at Geo type-I was 0.0085-0.0075, Geo type-II 0.004-0.0037, Geo type-III 0.0008, and countryside 0.00022-0.00019 in mg kg -1  day -1 adult-children, respectively, which was above the acceptable range (10 -6 -10 -4 ). ADI of F at Geo type-I was 0.0047-0.0041, Geo type-II 0.0098-0.0087, Geo type-III 0.002-0.0017 and countryside 0.0015-0.0013 in mg kg -1  day -1 adult-children, respectively. The toxicity level of Se and F at all the regions was lower than the NOAEL and LOAEL, while As was higher at Geo type-II and I. The extreme deficient of Se than the optimum range along with high F could deregulate the normal body growth especially causes bones and joint problems. However, the study found a rare patient with bone and joint disease (maybe Kashin-Beck disease) in the countryside. To find the exact cause of Kashin-Beck disease, the study needs further medical investigation in Se-deficient regions and their association with selenium deficiency and enriched fluoride.

A field study was conducted along a fluorine gradient of soil pollution in Tunisia from Gabes, the most polluted site, to Smara, the reference site. Variations of fluoride (F) concentrations in soils were detected over 1 year in Gabes, Skhira, and Smara. F concentrations in the aerial part of two native plant species, i.e., Erodium glaucophyllum and Rhanterium suaveolens, were above the usual background concentrations. Bioaccumulation factors ranged from 0.08 to 1.3. With F concentrations in aerial parts up to 355 mg kg -1 , both species may be described as F accumulators. Both species showed an earlier vegetative growth in Gabes than in Smara. However, some difference between their strategies could be observed, i.e., E. glaucophyllum shortening the period of its vegetative growth with an escape strategy and R. suaveolens decreasing its ratio of alive/dead parts potentially lowering the F toxicity by storage in dead cells. However, at a tissue level, mechanisms of tolerance were similar. Leaf section micrographs of both species showed a higher calcium accumulation in leaf midveins at Gabes than at Smara, confirming the role of calcium in plant F tolerance strategies.

We have studied the formation of fluorine- and chlorine-bearing species for a variety of dense interstellar conditions using a gas-grain network. Our homogeneous models have been constructed for low-temperature dense clouds, as well as warm-up regions. In addition to the observed species HF, , HCl, , and , we have included a number of additional halogen-containing molecules, and explored their gas-phase and grain-surface chemistry. These molecules include neutral species such as Cl2, ClO, CCl, and HCCl, as well as the carbon–halogen species CH2Cl and CH3Cl, and ionic species such as , , CH3ClH+, , , and . Predictions are made for the abundances of these species as functions of time, and comparisons are made with the observed abundances obtained for halogen species in dense regions, which include HF, HCl, CH3Cl, and CF+. The peak fractional abundance of the newly detected gas-phase CH3Cl is predicted to be in our warm-up simulations, depending upon density and the age of the pre-warm-up phase after which warm-up begins. These values can be compared with the observed abundance of methyl chloride in the hot corino IRAS 16293-2422 if the abundance of methanol is known. [ABSTRACT FROM AUTHOR]

We measured the L-shell emission spectrum of Fe xvii in a low-density, low-gradient magnetically confined laboratory plasma that contains predominately C, O, Fe, and Ni as trace elements and found excellent agreement with the relative spectral emission obtained in solar and astrophysical observations. However, we obtained spectra that appear to have an usually large Fe xvii resonance transition, which is commonly labeled , from hot plasmas that also contain fluorine. The wavelength of the Lyα feature of F ix is coincident with the wavelength of the Fe xvii line within one part in 538, and its flux, therefore, enhances the Fe xvii resonance line. Moreover, the resonance and forbidden lines of F viii are close to the transitions in Fe xvii and may further alter the inferred apparent Fe xvii line ratios, particularly in spectrometers with moderate spectral resolution. The enhanced emission of line can thus serve as a new spectral diagnostic for the detection of fluorine in astrophysical plasmas. [ABSTRACT FROM AUTHOR]

The single thiolated arylethynylene molecule with 9,10-dihydroanthracene core (denoted as TADHA) possesses pronounced negative differential conductance (NDC) behavior at lower bias regime. The adsorption effects of F2 molecule on the current and NDC behavior of TADHA molecular junctions are studied by applying non-equilibrium Green’s formalism combined with density functional theory. The numerical results show that the F2 molecule adsorbed on the benzene ring of TADHA molecule near the electrode can dramatically suppresses the current of TADHA molecular junction. When the F2 molecule adsorbed on the conjugated segment of 9,10-dihydroanthracene core of TADHA molecule, an obviously asymmetric effect on the current curves induces the molecular system showing apparent rectifier behavior. However, the current especially the NDC behavior have been significantly enlarged when F2 addition reacted with triple bond of TADHA molecule. [ABSTRACT FROM AUTHOR]

The Yangtze River drainage basins are China's most important economic development zones and also the locations of several large-scale fluorine chemical industries. In order to reveal the contribution from the tributaries at the dividing point between the middle and lower reaches of the Yangtze River with respect to perfluorinated substances (PFASs), 17 PFAS compounds in surface water, groundwater, and tap water samples were analyzed in the tributary system of the Jiujiang section of the Yangtze River. The total concentrations of PFASs in the surface waters ranged from 7.8 to 586.2 ng/L. High proportion of short-chain compound PFBS in surface waters in Nanchang City, Poyang Lake, and the Yangtze River was observed which is likely of WWTPs' origin.

Fluorosis is still a serious public health problem in China according to our field investigation. Current foodstuff drying methods were studied to evaluate the state of foodstuff contamination, including burning mixed coal (MC)/coal washing wastes (CWWs)/lump coal (LC)/fuelwood/fine coal + fixing materials (FCFM)/CWWs + fixing materials (CFM) in open stove (OS), honeycomb briquettes (HB) in improved stove (IS), sun-drying. The results demonstrate that elemental contents of F, As, Cd, Cr and Pb in roasted grain were 1.19-40.65 times higher than limting standard. The comprehensive risk of different drying methods based on AHP-FCE is ranked in the order of: CWWs(OS) > MC(OS) > HB(IS) > CFM(OS) > FCFM(OS) > LC(OS) > Fuelwood(OS) > sun-drying. It exhibits obviously higher risk due to burning CWWs/MC in OS than other methods. Burning CFM/FCFM/fuelwood in OS may be an economic and relatively safe foodstuff drying methods., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

We developed carriers of a 19 F magnetic resonance imaging ( 19 F MRI) agent, capable of responding to the temperature difference for cancer diagnosis. The carriers were based on high melting point (mp) neutral lipids, namely, tripalmitin (TPT) and tristearin (TSR) and triarachidin (TAC). Lipid nano-emulsions (LNEs) containing a fluorine compound, i.e., a modified α-tocopherol ( 19 F-TP), were respectively prepared as TPT-LNE, TSR-LNE, TAC-LNE1, and TAC-LNE2 and studied by 19 F NMR spectroscopy. In LNE prepared with soybean oil as a control, the full width at half maximum (FWHM) values of the 19 F NMR signal of 19 F-TP remained constant at 25, 37, and 42°C, while those of the LNEs prepared from a neutral lipid with a high mp showed a sharp decrease between 25 and 37°C. The magnitude of the decrease followed the order: TPT-LNE < TSR-LNE < TAC-LNE1. However, TAC-LNE2, for which the amount of encapsulated 19 F-TP was one third less than that of TAC-LNE1, showed a sharp decline in the FWHM between 37 and 42°C. To examine these changes, the 19 F spin-lattice (T 1 ) and spin-spin (T 2 ) relaxation times of 19 F-TP were measured. TAC-LNE2 in particular showed a substantial change in its T 2 value between 37 and 42°C compared with the change of its T 1 value. This result was attributed to activation of the molecular motion of 19 F-TP in TAC-LNE2 from 37 to 42°C. Thus, TAC-LNE showed potential for use as a carrier for cancer diagnosis using 19 F MRI.

Diamond like carbon (DLC) films were deposited onto Ti6Al4V and Si wafer substrates by RF plasma enhanced chemical vapor deposition. The influence of dopants such as fluorine (F), silicon (Si), and nitrogen (N) on composition, structure, and biocompatibility was investigated. Ion scattering spectroscopy analysis revealed the presence of dopant atoms in the outer-most layers of the films. Raman studies showed that the position of the G-band shifts to higher frequencies with the fluorine and nitrogen content in the DLC film, whereas the incorporation of Si into DLC induces a decrease of the position of the G peak. The corrosion behavior was studied in simulated body fluid. A higher charge transfer resistance (R ct ) was observed for the doped DLC films. The indirect cytotoxicity was performed using L929 fibroblast cells. The coated surfaces were hemocompatible when tested with red blood cells. DLC films were noncytotoxic to L929 cells over a 24 h exposure. Saos-2 osteoblast cell response to the doped and undoped DLC coated surfaces was studied in adhesion, proliferation, differentiation, and mineralization assays. The production of calcium and phosphate by cells on doped DLC, particularly, nitrogen doped DLC, was higher than that on undoped DLC.

Protein-Observed Fluorine NMR (PrOF NMR) spectroscopy is an emerging technique for screening and characterizing small-molecule-protein interactions. The choice of which amino acid to label for PrOF NMR can be critical for analysis. Here we report the first use of a protein containing two different fluoroaromatic amino acids for NMR studies. Using the KIX domain of the CBP/p300 as a model system, we examine ligand binding of several small-molecule compounds elaborated from our previous fragment screen and identify a new ligand binding site distinct from those used by native transcription factors. This site was further supported by computational modeling (FTMap and Schrödinger) and 1 H, 15 N HSQC/HMQC NMR spectroscopy. Metabolic labeling with multiple fluorinated amino acids provides useful probes for further studying ligand binding and has led to new insight for allosterically regulating transcription-factor protein interactions with small-molecule ligands., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Waste disposal site is one of the important sinks of chemicals. A significant amount of perfluoroalkyl and polyfluoroalkyl substances (PFASs) such as perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorohexanoic acid (PFHxA) have been brought into it. Because of their aqueous solubility, PFASs are released to landfill effluent waters, from which PFASs are efficiently collected by adsorption technique using granular activated carbon (GAC). The exhausted GAC is reactivated by heating processes. The mineralization of PFASs during the reactivation process was studied. Being thermally treated in N 2 atmosphere, the recovery rate of mineralized fluorine and PFC homologues including short-chained perfluorocarboxylic acids was determined. If the reagent form of PFOA, PFHxA, and PFOS were treated at 700 °C, the recovery of mineralized fluorine was less than 30, 46, and 72 %, respectively. The rate increased to 51, 74, and 70 %, if PFASs were adsorbed onto GAC in advance; moreover, addition of excess sodium hydroxide (NaOH) improved the recovery to 74, 91, and 90 %. Residual PFAS homologue was less than 1 % of the original amount. Steamed condition did not affect destruction. The significant role of GAC was to suppress volatile release of PFASs from thermal ambient, whereas NaOH enhanced destruction and retained mineralized fluorine on the GAC surface. Comparing the recovery of mineralized fluorine, the degradability of PFOS was considered to be higher than PFOA and PFHxA. Whole mass balance missing 9~26 % of initial amount suggested formation of some volatile organofluoro compounds beyond analytical coverage.

A facile method for the difluorination of 3-substituted-2,6-dichloropyridines including highly selective 2,6-difluorination of 3-halo-2,6-dichloropyridines is demonstrated. [ABSTRACT FROM AUTHOR]

In the coupling reaction between amines and pyridines or pyrimidines the preferred coupling site can be tuned from the fluorine group bearing the N-heterocyclic ring to the chlorine group when changing from the pyridine ring to the pyrimidine ring. [ABSTRACT FROM AUTHOR]

In this study, we applied sparse multiple linear regression (SMLR) analysis to clarify the relationships between soil properties and adsorption characteristics for a range of soils across Japan and identify easily-obtained physical and chemical soil properties that could be used to predict K and n values of cadmium, lead and fluorine. A model was first constructed that can easily predict the K and n values from nine soil parameters (pH, cation exchange capacity, specific surface area, total carbon, soil organic matter from loss on ignition and water holding capacity, the ratio of sand, silt and clay). The K and n values of cadmium, lead and fluorine of 17 soil samples were used to verify the SMLR models by the root mean square error values obtained from 512 combinations of soil parameters. The SMLR analysis indicated that fluorine adsorption to soil may be associated with organic matter, whereas cadmium or lead adsorption to soil is more likely to be influenced by soil pH, IL. We found that an accurate K value can be predicted from more than three soil parameters for most soils. Approximately 65% of the predicted values were between 33 and 300% of their measured values for the K value; 76% of the predicted values were within ±30% of their measured values for the n value. Our findings suggest that adsorption properties of lead, cadmium and fluorine to soil can be predicted from the soil physical and chemical properties using the presented models., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This work presents ultrasound-assisted dispersive micro solid phase extraction (USA DMSPE) for preconcentration of fluorine (F) in water and herb samples. TiO 2 nanoparticles (NPs) were used as an adsorbent. The determination with slurry sampling was performed via molecular absorption of calcium monofluoride (CaF) at 606.440 nm using a high-resolution continuum source electrothermal absorption spectrometry (HR-CS ET MAS). Several factors influencing the efficiency of the preconcentration technique, such as the amount of TiO 2 , pH of sample solution, ultrasonication and centrifugation time and TiO 2 slurry solution preparation before injection to HR-CS ET MAS, were investigated in detail. The conditions of detection step (wavelength, calcium amount, pyrolysis and molecule-forming temperatures) were also studied. After extraction, adsorbent with the analyte was mixed with 200 μL of H 2 O to prepare a slurry solution. The concentration limit of detection was 0.13 ng mL -1 . The achieved preconcentration factor was 7. The relative standard deviations (RSDs, %) for F in real samples were 3-15%. The accuracy of this method was evaluated by analyses of certified reference materials after spiking: INCT-MPH-2 (Mixed Polish Herbs), INCT-SBF-4 (Soya Bean Flour), ERM-CAO11b (Hard Drinking Water) and TMDA-54.5 (Lake Ontario Water). The measured F contents in reference materials were in satisfactory agreement with the added amounts, and the recoveries were found to be 97-109%. Under the developed extraction conditions, the proposed method has been successfully applied for the determination of F in real water samples (lake, sea, tap water) and herbs.

This study was conducted to investigate the effects of excess dietary fluoride (F) on serum biochemical indices, egg quality, and concentrations of F in soft tissues, eggs, and serum of laying hens. Commercial laying hens (n = 576, 51 weeks of age) were randomly allotted to 6 treatments with 6 replicates of 16 birds. The basal diets contained fluorine inclusions at a level of 16 mg/kg, and graded sodium fluoride was added to the basal diet to achieve fluorine inclusions, respectively, at a level of 200, 400, 600, 800, and 1000 mg/kg in the experimental diets. Dietary F levels at 600, 800, and 1000 mg/kg decreased (P < 0.05) albumin height and yolk color, while eggshell strength and eggshell thickness significantly decreased at 800 and 1000 mg/kg, respectively, compared with the control group. Fluoride concentrations in eggshell, albumin, yolk, liver, kidney, ovary, and oviduct responded to dietary F levels positively, and F concentrations in eggshell were the highest. Fluorine concentrations in albumin and yolk increased with the feeding time at the same dietary F levels (P < 0.05). Dietary F level at 400 mg/kg increased serum calcium level and activity of glutamic oxalacetic transaminase (P < 0.05). In conclusion, dietary F levels at 600 mg/kg decreased albumin height and yolk color, while eggshell strength and eggshell thickness significantly decreased at 800 and 1000 mg/kg, respectively. F concentrations in soft tissues, albumin, yolk, and eggshell of layers had a positive correlation with dietary F levels. By disturbing Ca and phosphorus metabolism, dietary F levels affected the formation of eggshell, reducing eggshell strength and eggshell thickness.

Purpose: Cellular MRI) was used to detect implanted human mesenchymal stem cells (hMSCs) and the resulting macrophage infiltration that occurs in response to xenotransplantation., Methods: Human mesenchymal stem cells were prelabeled with a fluorine-19 ( 19 F) agent prior to implantation, allowing for their visualization and quantification over time. Following implantation of 1 × 10 6 19 F-labeled hMSCs into the mouse hind limb, longitudinal imaging was performed to monitor the stem cell graft. Macrophages were labeled in situ by the intravenous administration of an ultrasmall superparamagentic iron oxide (USPIO), allowing for tracking of the inflammatory response., Results: Quantification of 19 F MRI on day 0 agreed with the implanted number of cells, and 19 F signal decreased over time. By day 14, only 22% ± 11% of the original 19 F signal remained. In a second group, USPIO were administered intravenously after implantation of 19 F-labeled hMSCs. When imaged on day 2, a significant decrease in 19 F signal was observed compared to the first group alongside a large signal void region in the corresponding proton images. Immunohistochemistry confirmed the presence of iron-labeled macrophages in the stem cell tract., Conclusion: A dual-labeling technique was used to noninvasively track two distinct cell populations simultaneously. This information could be used to provide additional insight into the cause of graft failure. Magn Reson Med 78:713-720, 2017. © 2016 International Society for Magnetic Resonance in Medicine., (© 2016 International Society for Magnetic Resonance in Medicine.)

Total, bioaccessible and mobile concentrations of arsenic and fluorine are determined in polluted surface soil within the Comarca Lagunera region using standardized protocols to obtain a full description of the environmental behavior for these elements. The composition of mineral phases associated with them is evaluated with microscopic and spectroscopic techniques. Mineralogical characterizations indicate that ultra-fine particles (<1-5 μm) including mimetite-vanadite (Pb 5 (AsO 4 ) 3 Cl, Pb 5 (AsO 4 , VO 4 ) 3 Cl)-like, lead arseniate (Pb 3 (AsO 4 ) 2 )-like and complex arsenic-bearing compounds are main arsenic-bearing phases, while fluorite (CaF 2 ) is the only fluorine-bearing phase. Total fluorine and arsenic concentrations in surface soil range from 89.75 to 926.63 and 2.7-78.6 mg kg -1 , respectively, exceeding in many points a typical baseline value for fluorine (321 mg kg -1 ), and trigger level criterion for arsenic soil remediation (20 mg kg -1 ); whereas fluoride and arsenic concentrations in groundwater vary from 0.24 to 1.8 mg L -1 and 0.12-0.650 mg L -1 , respectively. The main bioaccessible percentages of soil in the gastric phase (SBRC-G) are estimated for arsenic from 1 to 63%, and this parameter in the intestinal phase (SBRC-I) fluorine from 2 to 46%, suggesting human health risks for this region. While a negligible/low mobility is found in soil for arsenic (0.1-11%), an important mobility is determined for fluorine (2-39%), indicating environmental risk related to potential fluorine release. The environmental and health risks connected to arsenic and fluorine are discussed based on experimental data., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The amino acid 4-fluoro-L-phenylalanine (4F-Phe) was introduced at the positions of Phe6 and Phe22 in the 29-residue polypeptide hormone glucagon by expressing glucagon in E. coli in the presence of an excess of 4F-Phe. Glucagon regulates blood glucose homeostasis by interaction with the glucagon receptor (GCGR), a class B GPCR. By referencing to the 4F-Phe chemical shifts at varying D 2 O concentrations, the solvent exposure of the two Phe sites along the glucagon sequence was determined, showing that 4F-Phe6 was fully solvent exposed and 4F-Phe22 was only partially exposed. The incorporation of fluorine atoms in polypeptide hormones paves the way for novel studies of their interactions with membrane-spanning receptors, specifically by differentiating between effects on the solvent accessibility, the line shapes, and the chemical shifts from interactions with lipids, detergents and proteins. Studies of interactions of GCGR with ligands in solution is at this point of keen interest, given that recent crystallographic studies revealed that an apparent small molecule antagonist actually binds as an allosteric effector at a distance of ~20 Å from the orthosteric ligand binding site (Jazayeri et al., in Nature 533:274-277, 2016).

Schiff base organic compound (SOC) has been prepared as a tritopic chemosensor for selective sensing by fluorescence signalling towards ions like Al 3+ , F - and explosive molecule like TNP. In general, fluorescence like photophysical property has been used for selective detection of analyte where Al 3+ and F - show turn-on fluorescence signal at different wavelengths (nm) however, quenching was found with TNP. As a consequence, the chemosensor has become a selective sensor for Al 3+ , F - and TNP. Reversibility of fluorescence responses for Al 3+ and F - are observed in presence of ammonium nitrate and H + respectively. Similar to the detection of TNP, the detection of explosive like NO 3 - salts is also essential from homeland security point of view. In the present work, the finding of reversible sequential fluorescence response can be promoted for fabrication of next generation AND-NOT-OR-NAND-XOR-XNOR-NOR based complex logic circuit which is applicable in photonics, security and other fields including inorganic and material science. In the case of TNP recognition, the pathway mainly depends on non-covalent interaction (quenching constant: 4.4 × 10 5  M -1 ) which is even better than the recently reported materials. Detection limit for Al 3+ , F - and TNP is 1 μM, 3 μM and 500 nM respectively. DFT-D3 has been carried out to explore the host⋯guest interaction along with the structure-property correlation of the present host-guest system. All three guest analytes have been detected inside the living cell at a certain level and in its consequence, the successful in vitro recognition ability of the SOCs inside human cell line HeLa has been explored too. In real time stepping, an easy to operate and an economically affordable pocket prototype has also been fabricated for on spot detection of TNP like explosive., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A colorimetric receptor L was prepared. Receptor L can selectively sense F - based on distinct color changes among a series of ions. It can selectively sense F - through an intramolecular hydrogen bond interaction. A Job plot indicated a 1:1 complexation stoichiometry between receptor L and F - . The association constant for L-F - in CH 3 CN was determined as 9.70 × 10 4  M -1 using a Stern-Volmer plot., (Copyright © 2016 John Wiley & Sons, Ltd.)

A method for total F determination in food and tea samples based on a mass-shift strategy using tandem inductively coupled plasma quadrupole mass spectrometry (ICP-MS-MS) was developed. This method consists of four steps: (1) conversion of the hardly ionized F atoms to BaF + via ICP, (2) use of the first quadrupole (Q1, set at 157) to ensure only the m/z 157 ions (i.e., 138 Ba 19 F + , 157 Gd + , and 138 Ba 18 OH + ) enter the reaction cell (RC), (3) shifting 138 Ba 19 F + to a new mass 138 Ba 19 F( 14 NH 3 ) 3 + by reacting with NH 3 in RC to avoid the interfering ions (i.e., 157 Gd + and 138 Ba 18 OH + ), and (4) passing interference-free 138 Ba 19 F( 14 NH 3 ) 3 + to the second quadrupole (Q2, set at 208) for detection by the MS detector. The mass-shift process of the target F (in ICP and RC) expected to follow the path: F + 138 Ba + → 157 BaF + + 3NH 3 → 208 BaF(NH 3 ) 3 + , while the reaction pathway of dominant 157 Gd + in RC proposed to 157 Gd + + NH 3 → 157 Gd 14 N 1 H + + nNH 3 → 157 Gd 14 N 1 H( 14 N 1 H 3 ) n + (n = 0-5). Under the optimized setting of tandem MS (Q1 → Q2 = 157 → 208) and RC reaction gas flow rate (NH 3 /He = 10:90, 8.0 mL min -1 ), the background equivalent concentrations (BECs) and limits of detection (LODs) were 0.021 and 0.022 μg mL -1 , respectively. The calibration curve was linear in the range between 0.1 and 10 μg mL -1 , with a correlation coefficient of R 2 = 0.9999. The results obtained for 14 different food-related standard reference materials (SRMs) were in good agreement with the certified values on a 95% confidence level. The proposed method was then employed to evaluate the F contents of 13 branded tea samples. The total F concentrations ranged from 39.2 to 93.2 μg g -1 . The tea infusions contained F between 23.5 and 85.4 μg g -1 , with an extraction efficiency of 56.0-91.6%, and the water-soluble F contents of a Pu'er brick tea were 58.7, 21.4, 3.82, and 1.41 μg g -1 for filtrates 1, 2, 3, and 4, respectively.

The Northern Daba Mountains (NDM) of Shaanxi Province, China, are a well-known selenium (Se)-rich area, and the area is also known for endemic fluorine (F) and arsenic (As) poisoning. In order to study the hydrochemical characteristics and trace element contents of the natural waters of this region, 62 water samples were collected from Lan'gao area in the NDM. The hydrochemical composition was principally characterized by Ca·Mg-HCO 3 ·SO 4 . F and As concentrations ranged from 0.01 to 0.67 mg/L and from 0.33 to 6.29 μg/L, respectively, lower than Chinese national standard and international guidelines for drinking water quality. One year of monitoring proved that F and As in natural water were not the sources of the local fluorosis and arseniasis in the NDM. The average Se concentration in fissure water was 5.20 μg/L. The average Se content of river water was 2.82 μg/L, 14 times that of the world's surface level (0.2 μg/L). The Se content in eight samples reached the Chinese national standards for mineral drinking water quality (>10 μg/L). Contrasting the water samples of May, July, and September in 2015 shows that the Se content is relatively stable and the increase of humidity might be beneficial to increase the content of selenium and strontium in water.

To explore the residual characteristics of fluorine and perfluorinated compounds (PFCs) in tea, the total fluorine (TF), extractable organofluorine (EOF) and PFCs in 19 Chinese commercial teas of five categories were measured using cyclic neutron activation analysis combined with HPLC-MS/MS. The results showed that fluorine mainly existed as inorganic fluorine in teas, and identified fluorine (∑PFCs quantified as F) only accounted for 0.023-0.41% of EOF, indicating that most EOF in tea were still unknown. 50-99% of ∑PFCs in tea were short-chain (C⩽6), while perfluorooctanoic acid was the typical PFCs residual species. Less fermented teas contained significantly higher PFCs (mean, 20ng/g) than more fermented teas (3.0ng/g, p<0.01), suggesting that microbe may degrade PFCs during fermentation. The highest TF content was discovered in Hubei brick tea, which poses risk of fluorosis, whereas PFCs residues in teas caused no immediate harm., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Consumption of ready-to-drink beverages, as a potential source of fluoride (F), has increased considerably in China over the last decade. To help inform the public and policy makers, this study aimed to measure F concentration of ready-to-drink beverages on sale in Heilongjiang province, north east China. Three batches of 106 drink products manufactured by 26 companies were purchased from the main national supermarkets in Harbin, Heilongjiang province, China. The F concentration of all samples was determined, in triplicate, using a fluoride ion-selective electrode in conjunction with a meter and a direct method of analysis. The products were categorised into 10 groups according to product type. F concentrations of the samples ranged from 0.012-1.625 mg/l with a mean of 0.189 mg/l and a median of 0.076 mg/l. More than half of the products (55%) had an F concentration of ≤0.1 mg/l, while <5% had a F concentration of >0.7 mg/l. The 'tea with milk' group contained the highest mean F concentration (1.350 mg/l), whereas the lowest mean F concentration (0.027 mg/l) was found for the 'fruit juice' group. For some products, such as tea, fruit juice and carbonated beverages, there were substantial variations in F concentration between batches, manufacturers and production sites. In conclusion, ready-to-drink products (apart from tea), sold in Heilongjiang province, China, when consumed in moderation are unlikely to constitute a substantial risk factor for the development of dental or skeletal fluorosis.

The research was based on a pot experiment, in which the response of eight species of crops to soil contamination with fluorine was investigated. In parallel, some inactivating substances were tested in terms of their potential use for the neutralization of the harmful influence of fluorine on plants. The response of crops to soil contamination with fluorine was assessed according to the volume of biomass produced by aerial organs and roots as well as their content of N-total, N-protein, and N-NO 3 - . The following crops were tested: maize, yellow lupine, winter oilseed rape, spring triticale, narrow-leaf lupine, black radish, phacelia, and lucerne. In most cases, soil pollution with fluorine stimulated the volume of biomass produced by the plants. The exceptions included grain and straw of spring triticale, maize roots, and aerial parts of lucerne, where the volume of harvested biomass was smaller in treatments with fluorine-polluted soil. Among the eight plant species, lucerne was most sensitive to the pollution despite smaller doses of fluorine in treatments with this plant. The other species were more tolerant to elevated concentrations of fluorine in soil. In most of the tested plants, the analyzed organs contained more total nitrogen, especially aerial organs and roots of black radish, grain and straw of spring triticale, and aerial biomass of lucerne. A decrease in the total nitrogen content due to soil contamination with fluorine was detected only in the aerial mass of yellow lupine. With respect to protein nitrogen, its increase in response to fluorine as a soil pollutant was found in grain of spring triticale and roots of black radish, whereas the aerial biomass of winter oilseed rape contained less of this nutrient. Among the analyzed neutralizing substances, lime most effectively alleviated the negative effect of soil pollution with fluorine. The second most effective substance was loam, while charcoal was the least effective in this respect. Our results showed the effect of soil contamination with fluorine on the yield and chemical composition of fluorine depended on the species and organ of a tested plant, on the rate of the xenobotic element and on the substance added to soil in order to neutralize fluorine.

The analysis of fluorine was carried out by measuring BaF + ions with an inductively coupled plasma tandem quadrupole mass spectrometer (ICP-QMS/QMS). After optimization, a radio frequency power of 1300 W was found to benefit for the production of BaF + ions while suppressing the production of BaOH 3 + ions. After optimization of the reaction cell gas, it was found that the best performance for measuring BaF + could be achieved at a flow rate of O 2 in the range from 0.65 to 0.75 mL min -1 . The signal intensity of BaF + depended linearly on the concentration of Ba when it was not higher than 100 mg kg -1 . The co-existence of metallic cations, such as Na in the sample, might suppress the generation of BaF + ions in the plasma, while anions might not cause such a kind of interferences. The background equivalent concentration (BEC) and the lower detection limit (LDL) of fluorine were 0.4 and 0.06 mg kg -1 , respectively, by adjusting the samples to a 10 mg kg -1 Ba matrix. The concentration of fluorine in a certified reference material (ERM-CA015a) was determined with the present method, for which the observed value was (1.36 ± 0.05)mg kg -1 , which agreed with the certified value (1.3 ± 0.1)mg kg -1 , where both values were shown as (mean value ± expanded uncertainty) with a coverage factor of (k = 2) for calculating the expanded uncertainty giving a level of confidence of approximately 95%. The present method was applied to the analysis of a tap water sample collected in the laboratory, for which the results of recovery tests gave a recovery around 100% with good reproducibility.

A simple Schiff base (BMSA) prepared from salicylaldehyde and 2-(1H-benzo[d]imidazol-2-yl)aniline was evaluated as an efficient fluorescent chemosensor for the selective recognition of Al 3+ and Cu 2+ over other common metal ions. This sensor could detect Al3 + in CH 3 OH/PBS with distinct emission red-shift (the detection limit 0.31μM)and Cu 2+ in CH 3 OH/Tris-HCL (the detection limit 0.54μM) with obvious fluorescence quenching. The obtained BMSA-Al 3+ and BMSA-Cu 2+ complexes could act as cascade sensors for detecting F - and S 2- , respectively. The recognizing behavior of BMSA toward Al 3+ and Cu 2+ has been investigated in detail through Job's Plot, FT-IR NMR, and HRMS analysis. Moreover, this chemosensor was verified to be of low cytotoxicity and good imaging characteristics for the detection of Al 3 + and Cu 2+ , and further for the recognition of F - and S 2- in living cells, suggesting that BMSA was proved to be a useful tool for tracking Al3 + /Cu 2+ and F - /S 2- ions in vivo., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Alkyl-substituted 2-fluoroallyl acetates do not provide the desired products. [ABSTRACT FROM AUTHOR]

Optimized reaction conditions are developed for the regioselective allylic fluorination of alkenes via a tandem fluoroselenation-deselenation process. [ABSTRACT FROM AUTHOR]

This study describes the applicability of solid sampling technique for the determination of fluorine in various baby foods via molecular absorption of calcium monofluoride generated in a graphite furnace of high-resolution continuum source atomic absorption spectrometry. Fluorine was determined at CaF wavelength, 606.440nm in a graphite tube applying a pyrolysis temperature of 1000°C and a molecule forming temperature of 2200°C. The limit of detection and characteristic mass of the method were 0.20ng and 0.17ng of fluorine, respectively. The fluorine concentrations determined in standard reference sample (bush branches and leaves) were in good agreement with the certified values. By applying the optimized parameters, the concentration of fluorine in various baby foods were determined. The fluorine concentrations were ranged from

The purpose of this study was to evaluate the refractive errors and the demographic associations between drinking water with excessive fluoride and normal drinking water among residents in Northern China. Of the 1843 residents, 1415 (aged ≥40 years) were divided into drinking-water-excessive fluoride (DWEF) group (>1.20 mg/L) and control group (≤1.20 mg/L) on the basis of the fluoride concentrations in drinking water. Of the 221 subjects in the DWEF group, with 1.47 ± 0.25 mg/L (fluoride concentrations in drinking water), the prevalence rates of myopia, hyperopia, and astigmatism were 38.5 % (95 % confidence interval [CI] = 32.1-45.3), 19.9 % (95 % CI = 15-26), and 41.6 % (95 % CI = 35.1-48.4), respectively. Of the 1194 subjects in the control group with 0.20 ± 0.18 mg/L, the prevalence of myopia, hyperopia, and astigmatism were 31.5 % (95 % CI = 28.9-34.2), 27.6 % (95 % CI = 25.1-30.3), and 45.6 % (95 % CI = 42.8-48.5), respectively. A statistically significant difference was not observed in the association of spherical equivalent and fluoride concentrations in drinking water (P = 0.84 > 0.05). This report provides the data of the refractive state of the residents consuming drinking water with excess amounts of fluoride in northern China. The refractive errors did not result from ingestion of mild excess amounts of fluoride in the drinking water.

Source apportionment of fluorine pollution in the regional shallow groundwater at You'xi County, southeast China, has been analyzed by means of monitoring F(-) ion change characteristics in this area. Meanwhile, pollution sources and influencing factors of the shallow groundwater have been uncovered by studying the correlation between F(-) and other related ions such as Na(+), Ca(2+), Cl(-), NO3(-), HCO3(-), as well as (K(+) + Na(+))/Ca(2+) ratio (R) and pH effect. The results show that F(-) ions in shallow groundwater at the study area come mainly from the dissolution of fluorinated minerals in a form of fluorite (CaF2), the so-called water-rock interaction, and there is a higher possibility for the occurrence of fluorine water where the ratio of (K(+) + Na(+))/Ca(2+) exceeds a value of 2.1. Moreover, the release and migration of F(-) ions have been favored by the alkaline environment in this study area., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Fluorine determination in airborne samples is important due to its spread into the air from both natural and artificial sources. It can travel by wind over large distances before depositing on the Earth's surface. Its concentration in various matrices are limited and controlled by the regulations for causing health risks associated with environmental exposures. In this work, fluorine was determined in PM2.5 airborne samples by high-resolution continuum source electrothermal atomic absorption spectrometry. For these purpose, the PM2.5 airborne particulates were collected on quartz filters using high-volume samplers (500 L/min) in Istanbul (Turkey) for 96 h during January to June in 2 years. Then, instrumental and experimental parameters were optimized for the analyte in airborne samples. The validity of the method for the analyte was tested using standard reference material, and certified values were found in the limits of 95 % confidence level. The fluorine concentrations and meteorological conditions were compared statistically.