Quasi-particle energies and optical excitations of hydrogenated and fluorinated germanene.

Science.gov (United States)

Shu, Huabing; Li, Yunhai; Wang, Shudong; Wang, Jinlan

2015-02-14

Using density functional theory, the G0W0 method and Bethe-Salpeter equation calculations, we systematically explore the structural, electronic and optical properties of hydrogenated and fluorinated germanene. The hydrogenated/fluorinated germanene tends to form chair and zigzag-line configurations and its electronic and optical properties show close geometry dependence. The chair hydrogenated/fluorinated and zigzag-line fluorinated germanene are direct band-gap semiconductors, while the zigzag-line hydrogenated germanene owns an indirect band-gap. Moreover, the quasi-particle corrections are significant and strong excitonic effects with large exciton binding energies are observed. Moreover, the zigzag-line hydrogenated/fluorinated germanene shows highly anisotropic optical responses, which may be used as a good optical linear polarizer.

Investigation of fluorine adsorption on nitrogen doped MgAl{sub 2}O{sub 4} surface by first-principles

Energy Technology Data Exchange (ETDEWEB)

Lv, Xiaojun; Xu, Zhenming [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Li, Jie, E-mail: 15216105346@163.com [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Chen, Jiangan [Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Liu, Qingsheng [Faculty of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China)

2016-07-15

Graphical abstract: First-principles calculations indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, but hydrophobic. N doped MgAl{sub 2}O{sub 4} (100) surface structure shows the highest fluorine adsorption performance and fluorine atom is more preferentially adsorbed on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). N doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Highlights: • MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. • Fluorine preferentially adsorbs on the Mg-Al bridge site. • Adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} > Al{sub 2}O{sub 3} > MgAl{sub 2}O{sub 4} > MgO. • Excellent adsorption performance attributes to electron compensation of N atom. • Nitrogen doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Abstract: The nature of fluorine adsorption on pure and N doped MgAl{sub 2}O{sub 4} surface has been investigated by first-principles calculations based on the density functional theory. Calculated results indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. Nitrogen doped MgAl{sub 2}O{sub 4} (100) surface shows the highest fluorine adsorption performance and fluorine atom preferentially adsorbs on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: Nitrogen doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). In-depth PDOS analysis suggested that 2p orbitals of F atom strongly hybridized with 3s- and 3p-orbitals of Al atom contribute to its high adsorption intensity. According to the analysis of Hirshfeld charge, the excellent fluorine adsorption performance of nitrogen doped MgAl{sub 2}O{sub 4} attributes to the electron compensation effect of nitrogen atom and strong electrostatic interactions. All these

Bacterial adherence on fluorinated carbon based coatings deposited on polyethylene surfaces

International Nuclear Information System (INIS)

Terriza, A; Del Prado, G; Perez, A Ortiz; Martinez, M J; Puertolas, J A; Manso, D Molina; Gonzalez-Elipe, A R; Yubero, F; Barrena, E Gomez; Esteban, J

2010-01-01

Development of intrinsically antibacterial surfaces is of key importance in the context of prostheses used in orthopaedic surgery. In this work we present a thorough study of several plasma based coatings that may be used with this functionality: diamond like carbon (DLC), fluorine doped DLC (F-DLC) and a high fluorine content carbon-fluor polymer (CF X ). The study correlates the surface chemistry and hydrophobicity of the coating surfaces with their antibacterial performance. The coatings were deposited by RF-plasma assisted deposition at room temperature on ultra high molecular weight polyethylene (UHMWPE) samples. Fluorine content and relative amount of C-C and C-F bond types was monitored by X-ray photoelectron spectroscopy and hydrophobicity by water contact angle measurements. Adherence of Staphylococcus aureus and Staphylococcus epidermidis to non-coated and coated UHMWPE samples was evaluated. Comparisons of the adherence performance were evaluated using a paired t test (two materials) and a Kruskall Wallis test (all the materials). S. aureus was statistically significant (p< 0.001) less adherent to DLC and F-DLC surfaces than S. epidermidis. Both bacteria showed reduction of adherence on DLC/UHMWPE. For S. aureus, reduction of bacterial adherence on F-DLC/UHMWPE was statistically significant respect to all other materials.

The influence of diffusion of fluorine compounds for silicon lateral etching

Energy Technology Data Exchange (ETDEWEB)

Verdonck, Patrick; Goodyear, Alec; Braithwaite, Nicholas St.John

2004-07-01

In an earlier study, it was proposed that long-range surface transport of fluorine atoms could precede the eventual binding to a silicon atom. The rate of binding increases if the silicon is bombarded with high energy ions. In this study, the lateral etching of a silicon layer, sandwiched between two silicon dioxide layers, was studied in order to investigate and extend these hypotheses. The under etching of the silicon layer was higher for wafers which suffered ion bombardment, showing that this mechanism is important even for horizontal etching. At the same time, the thickness of the silicon layer was varied. In all cases, the thinner silicon layer etched much faster then the thicker layer, indicating that fluorine surface transport is much more important than re-emission for these processes. The etch rate increase with ion bombardment can be explained by the fact that part of the energy of the incoming ions is transferred to the fluorine compounds which are on the horizontal surfaces and that ion bombardment enhances the fluorine surface transport.

Synthesis and properties of a novel UV-cured fluorinated siloxane graft copolymer for improved surface, dielectric and tribological properties of epoxy acrylate coating

International Nuclear Information System (INIS)

Yan, Zhenlong; Liu, Weiqu; Gao, Nan; Wang, Honglei; Su, Kui

2013-01-01

A novel functional fluorinated siloxane graft copolymer bearing with vinyl end-groups was synthesized from dihydroxypropyl-terminated poly(dimethylsiloxane) (PDMS), dicarboxyl terminated poly(2,2,3,4,4,4-hexafluorobutyl acrylate) oligomer (CTHFA), 2,4-toluene diissocyanate (TDI) and 2-hydroxyethyl methacrylate (HEMA). The chemical structure was characterized by FT-IR and GPC. The effect of concentration of the vinyl-capped fluorosilicone graft copolymer (Vi-PFSi) on the surface, thermal properties, dielectric and tribological properties of UV-cured films was investigated. Contact angles and surface energies showed that the high hydrophobic and oleophobic surfaces were obtained by incorporation of Vi-PFSi at very low amount (0.5 wt%). X-ray photoelectron spectroscopy (XPS) evidenced that the fluorinated and siloxane moiety selectively migrated to the outermost surface of UV-cured film, thus reduced its surface energy from 45.42 to 15.40 mN/m 2 without affecting its bulk properties. The morphology of fracture surface of modified film exhibited rough fracture surface only at the outermost surface, revealing fluorinated and siloxane groups migrated toward air-side surface. The dielectric constants decreased from 5.32 (1 MHz) for bisphenol-A epoxy methacrylate (EMA) to 2.82 (1 MHz) for modified film when the Vi-PFSi copolymer concentration increased from 0 to 0.8 wt%. Tribological results from abrasion tester suggested that the Vi-PFSi could obviously reduce the abrasion weight loss of modified films.

Electron energy-loss spectra in molecular fluorine

Science.gov (United States)

Nishimura, H.; Cartwright, D. C.; Trajmar, S.

1979-01-01

Electron energy-loss spectra in molecular fluorine, for energy losses from 0 to 17.0 eV, have been taken at incident electron energies of 30, 50, and 90 eV and scattering angles from 5 to 140 deg. Features in the spectra above 11.5 eV energy loss agree well with the assignments recently made from optical spectroscopy. Excitations of many of the eleven repulsive valence excited electronic states are observed and their location correlates reasonably well with recent theoretical results. Several of these excitations have been observed for the first time and four features, for which there are no identifications, appear in the spectra.

FY 1995 development of fluorinated hydriding alloys with multi functional and functionally-graded surface and their application to energy conversion devices; 1995 nendo keishagata fukugo kino wo hyomen ni motsu suiso kyuzo gokin no kaihatsu to energy henkan gijutsu eno oyo

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

The project is the extended researches of a fluorination technique invented by the project leader (Suda) for improving the surface properties and characteristics of conventional hydriding alloys from the following viewpoints; (1) To investigate the roles of fluorinated surface during hydrogen uptake both in the gas-solid and the electrochemical reactions. (2) To elucidate the factors which increase the protective nature of the surface. (3) To develop a material design procedure for synthesizing thin layer of functionally graded surface which is composed of metallic Ni and the fluoride compound. (1) An advanced fluorination technique was developed to incorporate metallic Ni in the surface fluoride layer. (2) Metallic Ni was successfully distributed in a functionally graded manner in the Surface fluoride layer. (3) Through the technique developed, the following properties and characteristics were successfully donated in the fluorinated hydriding alloys such as AB{sub 5}, AB{sub 2}, and AB; (3-1)Surface oxides which act as the resistant layer to the hydrogen up take was completely eliminated to result in the enhancement of the initial activation characteristics. (3-2) Hydrogen selectivity and permeability was greatly improved. (3-3) Surface protective nature against the impurity gases and contaminants was significantly improved. (3-4) Initial activation characteristics both in the gas-solid and the electrochemical reactions were distinguishably improved. (3-5) Fluorinated surface was found to function as the catalyst for a methanation reaction between the CO{sub 2} gas adsorbed over the fluorinated surface and the monatomic hydrogen absorbed in the metal lattice of the crystalline structure of the hydriding alloys. (4) A technique was developed for increasing the specific surface area and decreasing the specific surface diameter of the fluorinated hydriding alloy articles. (NEDO)

Improvement of suspension stability and electrophoresis of nanodiamond powder by fluorination

Energy Technology Data Exchange (ETDEWEB)

Huang, H.; Wang, Y.H. [State Key Laboratory of Metastable Material Science and Technology, College of Material Science and Engineering, Hebei Street, Yanshan University, Qinhuangdao 066004 (China); Zang, J.B., E-mail: diamondzjb@163.com [State Key Laboratory of Metastable Material Science and Technology, College of Material Science and Engineering, Hebei Street, Yanshan University, Qinhuangdao 066004 (China) and State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083 (China); Bian, L.Y. [State Key Laboratory of Metastable Material Science and Technology, College of Material Science and Engineering, Hebei Street, Yanshan University, Qinhuangdao 066004 (China)

2012-02-01

Fluorinated nanodiamond (F-ND) was prepared by annealing ND in fluorine gas. The fluorine gas was periodically fed to ensure uniform exposure of every diamond nanoparticle in homogenous reactive ambience. The characteristics of the F-ND particles were investigated by the following methods: Fourier-transform infrared absorption spectroscopy, energy-dispersive X-ray spectrometer, X-ray diffraction, and transmission electron microscopy. The results showed that the fluorine atoms were chemically adsorbed on the surface of the ND particles and consequently formed C-F bonds. Fluorine of 6.4 wt.% was detected on the F-ND surface. The aggregated ND particles were disintegrated by the fluorination and the size of aggregated ND was reduced from approximately several hundred nanometers to about 40 nm. The stability of the F-ND suspension in distilled water or ethanol was higher than that of the pristine ND suspension. The anodic electrophoretic deposition of the F-ND particles was derived using ethanol suspension, indicating that the F-ND particles were negatively charged.

Homocomposites of chopped fluorinated polyethylene fiber with low-density polyethylene matrix

International Nuclear Information System (INIS)

Maity, J.; Jacob, C.; Das, C.K.; Alam, S.; Singh, R.P.

2008-01-01

Conventional composites are generally prepared by adding reinforcing agent to a matrix and the matrix wherein the reinforcing agents are different in chemical composition with the later having superior mechanical properties. This work presents the preparation and properties of homocomposites consisting of a low-density polyethylene (LDPE) matrix and an ultra high molecular weight polyethylene (UHMWPE) fiber reinforcing phase. Direct fluorination is an important surface modification process by which only a thin upper layer is modified, the bulk properties of the polymer remaining unchanged. In this work, surface fluorination of UHMWPE fiber was done and then fiber characterization was performed. It was observed that after fluorination the fiber surface became rough. Composites were then prepared using both fluorinated and non-fluorinated polyethylene fiber with a low-density polyethylene (LDPE) matrix to prepare single polymer composites. It was found that the thermal stability and mechanical properties were improved for fluorinated fiber composites. X-ray diffraction (XRD) analysis showed that the crystallinity of the composites increased and it is maximum for fluorinated fiber composites. Tensile strength (TS) and modulus also increased while elongation at break (EB) decreased for fiber composites and was a maximum for fluorinated fiber composites. Scanning electron microscopic analysis indicates that that the distribution of fiber into the matrix is homogeneous. It also indicates the better adhesion between the matrix and the reinforcing agent for modified fiber composites. We also did surface fluorination of the prepared composites and base polymer for knowing its application to different fields such as printability wettability, etc. To determine the various properties such as printability, wettability and adhesion properties, contact angle measurement was done. It was observed that the surface energies of surface modified composites and base polymer increases

Surface modification of titanium aluminides with fluorine to improve their application for high temperature service conditions

International Nuclear Information System (INIS)

Zschau, Hans-Eberhard; Schuetze, Michael; Baumann, Horst; Bethge, Klaus

2007-01-01

Recently the target temperature of components manufactured from gamma-TiAl alloys like turbine blades, turbocharger rotors or automotive valves has been increased to 900 deg. C. However, there is an insufficient oxidation resistance above 750 deg. C. One method used to improve the gamma-TiAl oxidation behaviour is the so-called fluorine microalloying effect. After application of fluorine to the TiAl surface by ion implantation or treatment with diluted HF and oxidation at 900 deg. C in air a dense alumina layer is formed. However, after the treatments a distinct loss of fluorine was observed during heating and within the first hours of oxidation. In this work the long time behaviour during isothermal and cyclic oxidation up to 1500 h/900 deg. C/air was investigated showing a slow fluorine decrease. The alumina layer acts as a diffusion barrier for fluorine, whereas fluorine diffuses into the metal. The diffusion coefficient was calculated. The results fit the theoretical model of the fluorine effect

Structural And Energetic Changes of Si (100 Surface With Fluorine in Presence of Water – A Density Functional Study

Directory of Open Access Journals (Sweden)

Takeo Ebina

2001-05-01

Full Text Available Abstract: We report density functional electronic structure calculations to monitor the change in the surface characteristics of the Si (100-2x1 surface after fluorination followed by interaction with water. Embedded finite silicon clusters are used to model an extended Si (100-2x1 surface. Two high symmetry pathways and subsequent adsorption sites were examined: (i adsorption of an fluorine atom directing onto a silicon dangling bond to form a monocoordinated fluorine atom (ii adsorption of a fluorine atom directing on top of silicon dimer to form a bridging dicoordinated fluorine atom. However, in the later case we find that no barrier exists for the bridging fluorine atom to slide towards silicon dimer dangling bond to form more stable mono coordinated Si-F bond. We calculated activation barriers and equilibrium surface configuration as a function of fluorine coverage upto 2.0 ML. We compared the stability of the fluorinated surface. The results were compared with existing experimental and theoretical results. The reaction of water with HF treated Si surface is monitored. It produces, as a first step, the exchange of Si-F with water to form Si-OH groups reducing the concentration of the fluorine on the surface, followed by a rapture of Si-Si bonds and finally the Si-O-Si bridge formation in the lattice.

Morphology and Surface Energy of a Si Containing Semifluorinated Di-block Copolymer Thin Films.

Science.gov (United States)

Shrestha, Umesh; Clarson, Stephen; Perahia, Dvora

2013-03-01

The structure and composition of an interface influence stability, adhesiveness and response to external stimuli of thin polymeric films. Incorporation of fluorine affects interfacial energy as well as thermal and chemical stability of the layers. The incompatibility between the fluorinated and non-fluorinated blocks induces segregation that leads to long range correlations where the tendency of the fluorine to migrate to interfaces impacts the surface tension of the films. Concurrently Si in a polymeric backbone enhances the flexibility of polymeric chains. Our previous studies of poly trifluoro propyl methyl siloxane-polystyrene thin films with SiF fraction 0.03-0.5 as a function of temperature have shown that the SiF block drives layering parallel to the surface of the diblock. Here in we report the structure and interfacial energies of SiF-PS in the plane of the films, as a function of the volume fraction of the SiF block obtained from Atomic Force microscopy and contact angle measurement studies. This work is supported by NSF DMR - 0907390

Studies on nitrile rubber degradation in zinc bromide completion fluid and its prevention by surface fluorination

Science.gov (United States)

Vega-Cantu, Yadira Itzel

Poly(acrylonitrile-co-butadiene) or nitrile-butadiene rubber (NBR) is frequently used as an O-ring material in the oil extraction industry due to its excellent chemical properties and resistance to oil. However, degradation of NBR gaskets is known to occur during the well completion and oil extraction process where packers are exposed to completion fluids such as ZnBr2 brine. Under these conditions NBR exhibits accelerated chemical degradation resulting in embrittlement and cracking. Samples of NBR, poly(acrylonitrile) (PAN) and poly(butadiene) (PB) have been exposed to ZnBr2 based completion fluid, and analyzed by ATR and diffuse reflectance IR. Analysis shows the ZnBr2 based completion fluid promotes hydrolysis of the nitrile group to form amides and carboxylic groups. Analysis also shows that carbon-carbon double bonds in NBR are unaffected after short exposure to zinc bromide based completion fluid, but are quickly hydrolyzed in acidic bromide mixtures. Although fluoropolymers have excellent chemical resistance, their strength is less than nitrile rubber and replacing the usual gasket materials with fluoroelastomers is expensive. However, a fluoropolymer surface on a nitrile elastomer can provide the needed chemical resistance while retaining their strength. In this study, we have shown that this can be achieved by direct fluorination, a rather easy and inexpensive process. Samples of NBR O-rings have been fluorinated by exposure to F2 and F2/HF mixtures at various temperatures. Fluorination with F 2 produces the desired fluoropolymer layer; however, fluorination by F2/HF mixtures gave a smoother fluorinated layer at lower temperatures and shorter times. Fluorinated samples were exposed to ZnBr2 drilling fluid and solvents. Elemental analysis shows that the fluorinated layer eliminates ZnBr2 diffusion into the NBR polymeric matrix. It was also found that surface fluorination significantly retards the loss of mechanical properties such as elasticity, tensile

Hydrolytically stable fluorinated metal-organic frameworks for energy-efficient dehydration

KAUST Repository

Cadiau, Amandine

2017-05-18

Natural gas must be dehydrated before it can be transported and used, but conventional drying agents such as activated alumina or inorganic molecular sieves require an energy-intensive desiccant-regeneration step. We report a hydrolytically stable fluorinated metal-organic framework, AlFFIVE-1-Ni (KAUST-8), with a periodic array of open metal coordination sites and fluorine moieties within the contracted square-shaped one-dimensional channel. This material selectively removed water vapor from gas streams containing CO2, N2, CH4, and higher hydrocarbons typical of natural gas, as well as selectively removed both H2O and CO2 in N2-containing streams. The complete desorption of the adsorbed water molecules contained by the AlFFIVE-1-Ni sorbent requires relatively moderate temperature (~105°C) and about half the energy input for commonly used desiccants.

Grafting of cellulose by fluorine-bearing silane coupling agents

International Nuclear Information System (INIS)

Ly, B.; Belgacem, M.N.; Bras, J.; Brochier Salon, M.C.

2010-01-01

The surface of model cellulose fibres, Avicell (AV), as well as that of Whatman paper (WP) was chemically modified with two fluorine-bearing alkoxysilane coupling agents, namely: 3,3,3-trifluoropropyl trimethoxysilane (TFPS) and 1H,1H,2H,2H,perfluorooctyl trimethoxysilane (PFOS). The occurrence of the grafting of soxhlet extracted modified cellulose was confirmed by the presence of silicon and fluorine atoms detected by elemental analysis, X-ray photoelectron spectroscopy and Electron Dispersion Energy/Scanning Electron Microscopy (EDS/SEM). The contact angle measurements showed that, after grafting, the surface of AV and WP samples became totally highly hydrophobic with a contact angle of 140 deg. Thus, the polar contribution to the surface energy of the modified substrates was found to be close to zero. These modified substrate could be interesting for application such as self-cleaning surface, wipes paper, grease barrier paper or for biocomposite with a polar matrix.

Effects of surface chemical properties of activated carbon modified by amino-fluorination for electric double-layer capacitor.

Science.gov (United States)

Jung, Min-Jung; Jeong, Euigyung; Cho, Seho; Yeo, Sang Young; Lee, Young-Seak

2012-09-01

The surface of phenol-based activated carbon (AC) was seriatim amino-fluorinated with solution of ammonium hydroxide and hydrofluoric acid in varying ratio to fabricate electrode materials for use in an electric double-layer capacitor (EDLC). The specific capacitance of the amino-fluorinated AC-based EDLC was measured in a 1 M H(2)SO(4) electrolyte, in which it was observed that the specific capacitances increased from 215 to 389 Fg(-1) and 119 and 250 Fg(-1) with the current densities of 0.1 and 1.0 Ag(-1), respectively, in comparison with those of an untreated AC-based EDLC when the amino-fluorination was optimized via seriatim mixed solution of 7.43 mol L(-1) ammonium hydroxide and 2.06 mol L(-1) hydrofluoric acid. This enhancement of capacitance was attributed to the synergistic effects of an increased electrochemical activity due to the formation of surface N- and F-functional groups and increased, specific surface area, and mesopore volumes, all of which resulted from the amino-fluorination of the electrode material. Copyright © 2012 Elsevier Inc. All rights reserved.

Synergistic effects of hollow structure and surface fluorination on the photocatalytic activity of titania

International Nuclear Information System (INIS)

Lv Kangle; Yu Jiaguo; Deng Kejian; Sun Jie; Zhao Yanxi; Du Dongyun; Li Mei

2010-01-01

To study the synergistic effects of hollow structure and surface fluorination on the photoactivity of TiO 2 , TiO 2 hollow microspheres were synthesized by a hydrolysis-precipitate method using sulfonated polystyrene (PS) as templates and tetrabutylorthotitanate (TBOT) as precursor, and then calcined at 500 o C for 2 h. The calcined samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N 2 sorption. Photocatalytic activity was evaluated using reactive brilliant red X3B, an anionic organic dye, as a model pollutant in water. The results show that the photocatalytic activity of TiO 2 hollow microspheres is significantly higher than that of TiO 2 nanoparticles prepared in the same experimental conditions. At pH 7 and 3, the apparent rate constants of the former exceed that of the latter by a factor of 3.38 and 3.15, respectively. After surface fluorination at pH 3, the photoactivity of hollow microspheres and nanoparticles further increases for another 1.61 and 2.19 times, respectively. The synergistic effect of surface fluorination and hollow structure can also be used to prepare other highly efficient photocatalyst.

Macroscale tribological properties of fluorinated graphene

Science.gov (United States)

Matsumura, Kento; Chiashi, Shohei; Maruyama, Shigeo; Choi, Junho

2018-02-01

Because graphene is carbon material and has excellent mechanical characteristics, its use as ultrathin lubrication protective films for machine elements is greatly expected. The durability of graphene strongly depends on the number of layers and the load scale. For use in ultrathin lubrication protective films for machine elements, it is also necessary to maintain low friction and high durability under macroscale loads in the atmosphere. In this study, we modified the surfaces of both monolayer and multilayer graphene by fluorine plasma treatment and examined the friction properties and durability of the fluorinated graphene under macroscale load. The durability of both monolayer and multilayer graphene improved by the surface fluorination owing to the reduction of adhesion forces between the friction interfaces. This occurs because the carbon film containing fluorine is transferred to the friction-mating material, and thus friction acts between the two carbon films containing fluorine. On the other hand, the friction coefficient decreased from 0.20 to 0.15 by the fluorine plasma treatment in the multilayer graphene, whereas it increased from 0.21 to 0.27 in the monolayer graphene. It is considered that, in the monolayer graphene, the change of the surface structure had a stronger influence on the friction coefficient than in the multilayer graphene, and the friction coefficient increased mainly due to the increase in defects on the graphene surface by the fluorine plasma treatment.

Synthesis of polymeric fluorinated sol–gel precursor for fabrication of superhydrophobic coating

International Nuclear Information System (INIS)

Li, Qianqian; Yan, Yuheng; Yu, Miao; Song, Botao; Shi, Suqing; Gong, Yongkuan

2016-01-01

Graphical abstract: - Highlights: • A polymeric fluorinated sol–gel precursor PFT is designed to fabricate superhydrophobic coatings. • The superhydrophobicity could be governed by the concentration of PFT. • Bio-mimicking self-cleaning property similar to lotus leaves could also be achieved. - Abstract: A fluorinated polymeric sol–gel precursor (PFT) is synthesized by copolymerization of 2,3,4,5,5,5-hexafluoro-2,4-bis(trifluorinated methyl)pentyl methacrylate (FMA) and 3-methacryloxypropyltrimethoxysilane (TSMA) to replace the expensive long chain fluorinated alkylsilanes. The fluorinated silica sol is prepared by introducing PFT as co-precursor of tetraethyl orthosilicate (TEOS) in the sol–gel process with ammonium hydroxide as catalyst, which is then used to fabricate superhydrophobic coating on glass substrate through a simple dip-coating method. The effects of PFT concentrations on the chemical structure of the formed fluorinated silica, the surface chemical composition, surface morphology, wetting and self-cleaning properties of the resultant fluorinated silica coatings were studied by using X-ray powder diffraction (XRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectrophotometer (XPS), scanning electron microscopy (SEM) and water contact angle measurements (WCA). The results show that the fluorinated silica sols are successfully obtained. The size and size distribution of the fluorinated silica particles are found greatly dependent on the concentration of PFT, which play a crucial role in the surface morphology of the corresponding fluorinated silica coatings. The suitable PFT concentration added in the sol–gel stage, i.e. for F-sol-1 and F-sol-2, is helpful to achieve both the low surface energy and multi-scaled microstructures, leading to the formation of the superhydrophobic coatings with bio-mimicking self-cleaning property similar to lotus leaves.

Effect of plasma fluorination variables on the deposition and growth of partially fluorinated polymer over PMMA films

Directory of Open Access Journals (Sweden)

Giovana da Silva Padilha

2013-01-01

Full Text Available In this work, an investigation was made of the modification of film surface of Poly(methylmethacrylate (PMMA using the plasma polymerization technique. PMMA films 10 µm thick were obtained by Spin-Coating starting from a chloroform solution (15.36% w/w. The films were exposed to the plasma of CHF3 at different gas pressures and exposure times to increase the thickness of fluorinated polymers onto PMMA films. The plasma fluorinated optical films were characterized by gravimetry, FTIR-ATR, contact angle of wetting, SEM and AFM. The surface fluorination of PMMA films can be inferred by the increase in contact angle under all experimental conditions, and confirmed with FTIR-ATR analysis. Gravimetry showed an increase of the fluorinated polymer layer over PMMA films, being 1.55 µm thick at 0.7 torr and 40 minutes of plasma exposure. The SEM analysis showed a well-defined layer of fluorinated polymer, with fluorine being detected in the EDS analysis. The film roughness for the fluorinated polymers was around of 200 Å, quite satisfactory for a 1.55 µm cladding.

Fluorinated cobalt for catalyzing hydrogen generation from sodium borohydride

Energy Technology Data Exchange (ETDEWEB)

Akdim, O.; Demirci, U.B.; Brioude, A.; Miele, P. [Laboratoire des Multimateriaux et Interfaces, UMR 5615 CNRS Universite Lyon 1, Universite de Lyon, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne (France)

2009-07-15

The present paper reports preliminary results relating to a search for durable cobalt-based catalyst intended to catalyze the hydrolysis of sodium borohydride (NaBH{sub 4}). Fluorination of Co [Suda S, Sun YM, Liu BH, Zhou Y, Morimitsu S, Arai K, et al. Catalytic generation of hydrogen by applying fluorinated-metal hydrides as catalysts. Appl Phys A 2001; 72: 209-12.] has attracted our attention whereas the fluorination of Co boride has never been envisaged so far. Our first objective was to compare the reactivity of fluorinated Co with that of Co boride. We focused our attention on the formation of Co boride from fluorinated Co. Our second objective was to show the fluorination effect on the reactivity of Co. Our third objective was to find an efficient, durable Co catalyst. It was observed a limited stabilization of the Co surface by virtue of the fluorination, which made the formation of surface Co boride more difficult while the catalytic activity was unaltered. The fluorination did not affect the number of surface active sites. Nevertheless, it did not prevent the formation of Co boride. The fluorination of Co boride was inefficient. Hence, fluorination is a way to gain in stabilization of the catalytic surface but it is quite inefficient to hinder the boride formation. Accordingly, it did not permit to compare the reactivity of Co boride with that of Co. (author)

Surface properties and self-cleaning ability of the fluorinated acrylate coatings modified with dodecafluoroheptyl methacrylate through two adding ways

International Nuclear Information System (INIS)

Yang, Xin; Zhu, Liqun; Zhang, Yang; Chen, Yichi; Bao, Baiqing; Xu, Jinlong; Zhou, Weiwei

2014-01-01

Highlights: • A self-cleaning test is used to evaluate the self-cleaning ability of coatings. • Adding way of fluorine monomer has an influence on the self-cleaning ability. • The fluorine content of coating surface increases by changing modification method. • High contact angles and low sliding angles are advantageous for self-cleaning. • The self-cleaning ability of coatings is analyzed after scrubbing. - Abstract: The fluorine-modified acrylate resin was synthesized by solution radical polymerization using dodecafluoroheptyl methacrylate (DFMA) and other acrylate monomers. The same weight of DFMA was added into the reaction through two different ways: (1) adding DFMA as bottom monomer (AFBM); (2) adding DFMA drop by drop (AFDD). The different coatings were prepared by blending the fluorine-modified acrylate resin with the curing agent. Compared with AFDD coating, the AFBM coating exhibited better self-cleaning ability which was confirmed by the self-cleaning test through measuring the specular gloss of coatings before contamination and after water droplets flushing. The fluorine content at the surface of AFBM coating increased from 15.1 at.% to 23.1 at.%, while the water contact angles increased by 8° and the sliding angles decreased obviously. Furthermore, the contact angles and self-cleaning ability of the coatings prepared with DFMA through two adding ways both decreased after scrubbing by wet cotton because of the decrease of the surface fluorine atom content. It could be concluded that high contact angles and low sliding angles were advantageous for coatings to obtain excellent self-cleaning ability

Surface properties and self-cleaning ability of the fluorinated acrylate coatings modified with dodecafluoroheptyl methacrylate through two adding ways

Energy Technology Data Exchange (ETDEWEB)

Yang, Xin [Key Laboratory of Aerospace Advanced Materials and Performance (Ministry of Education), School of Material Science and Engineering, Beihang University, Beijing 100191 (China); Zhu, Liqun, E-mail: zhulq@buaa.edu.cn [Key Laboratory of Aerospace Advanced Materials and Performance (Ministry of Education), School of Material Science and Engineering, Beihang University, Beijing 100191 (China); Zhang, Yang [Key Laboratory of Aerospace Advanced Materials and Performance (Ministry of Education), School of Material Science and Engineering, Beihang University, Beijing 100191 (China); Chen, Yichi [Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing 100191 (China); Bao, Baiqing; Xu, Jinlong; Zhou, Weiwei [Jiangsu Baihe Coatings Co., Ltd, Changzhou 213136 (China)

2014-03-01

Highlights: • A self-cleaning test is used to evaluate the self-cleaning ability of coatings. • Adding way of fluorine monomer has an influence on the self-cleaning ability. • The fluorine content of coating surface increases by changing modification method. • High contact angles and low sliding angles are advantageous for self-cleaning. • The self-cleaning ability of coatings is analyzed after scrubbing. - Abstract: The fluorine-modified acrylate resin was synthesized by solution radical polymerization using dodecafluoroheptyl methacrylate (DFMA) and other acrylate monomers. The same weight of DFMA was added into the reaction through two different ways: (1) adding DFMA as bottom monomer (AFBM); (2) adding DFMA drop by drop (AFDD). The different coatings were prepared by blending the fluorine-modified acrylate resin with the curing agent. Compared with AFDD coating, the AFBM coating exhibited better self-cleaning ability which was confirmed by the self-cleaning test through measuring the specular gloss of coatings before contamination and after water droplets flushing. The fluorine content at the surface of AFBM coating increased from 15.1 at.% to 23.1 at.%, while the water contact angles increased by 8° and the sliding angles decreased obviously. Furthermore, the contact angles and self-cleaning ability of the coatings prepared with DFMA through two adding ways both decreased after scrubbing by wet cotton because of the decrease of the surface fluorine atom content. It could be concluded that high contact angles and low sliding angles were advantageous for coatings to obtain excellent self-cleaning ability.

Liquid-solid surface phase transformation of fluorinated fullerene on monolayer tungsten diselenide

KAUST Repository

Song, Zhibo

2018-04-04

Hybrid van der Waals heterostructures constructed by the integration of organic molecules and two-dimensional (2D) transition metal dichalcogenide (TMD) materials have useful tunable properties for flexible electronic devices. Due to the chemically inert and atomically smooth nature of the TMD surface, well-defined crystalline organic films form atomically sharp interfaces facilitating optimal device performance. Here, the surface phase transformation of the supramolecular packing structure of fluorinated fullerene (C60F48) on single-layer tungsten diselenide (WSe2) is revealed by low-temperature scanning tunneling microscopy, from thermally stable liquid to solid phases as the coverage increases. Statistical analysis of the intermolecular interaction potential reveals that the repulsive dipole-dipole interaction induced by interfacial charge transfer and substrate-mediated interactions play important roles in stabilizing the liquid C60F48 phases. Theoretical calculations further suggest that the dipole moment per C60F48 molecule varies with the surface molecule density, and the liquid-solid transformation could be understood from the perspective of the thermodynamic free energy for open systems. This study offers insights into the growth behavior at 2D organic/TMD hybrid heterointerfaces.

Liquid-solid surface phase transformation of fluorinated fullerene on monolayer tungsten diselenide

Science.gov (United States)

Song, Zhibo; Wang, Qixing; Li, Ming-Yang; Li, Lain-Jong; Zheng, Yu Jie; Wang, Zhuo; Lin, Tingting; Chi, Dongzhi; Ding, Zijing; Huang, Yu Li; Thye Shen Wee, Andrew

2018-04-01

Hybrid van der Waals heterostructures constructed by the integration of organic molecules and two-dimensional (2D) transition metal dichalcogenide (TMD) materials have useful tunable properties for flexible electronic devices. Due to the chemically inert and atomically smooth nature of the TMD surface, well-defined crystalline organic films form atomically sharp interfaces facilitating optimal device performance. Here, the surface phase transformation of the supramolecular packing structure of fluorinated fullerene (C60F48 ) on single-layer tungsten diselenide (WSe2) is revealed by low-temperature scanning tunneling microscopy, from thermally stable liquid to solid phases as the coverage increases. Statistical analysis of the intermolecular interaction potential reveals that the repulsive dipole-dipole interaction induced by interfacial charge transfer and substrate-mediated interactions play important roles in stabilizing the liquid C60F48 phases. Theoretical calculations further suggest that the dipole moment per C60F48 molecule varies with the surface molecule density, and the liquid-solid transformation could be understood from the perspective of the thermodynamic free energy for open systems. This study offers insights into the growth behavior at 2D organic/TMD hybrid heterointerfaces.

Fluorination reaction uranium dioxide by fluorine

International Nuclear Information System (INIS)

Ogata, Shinji; Homma, Shunji; Koga, Jiro; Matsumoto, Shiro; Sasahira, Akira; Kawamura, Fumio

2004-01-01

Kinetics of the fluorination reaction of uranium dioxide is studied using un-reacted core model with shrinking particles. The model includes the film mass transfer of fluorine gas and its diffusion in the particle. The rate constants of the model are determined by fitting the experimental data for 370-450degC. The model successfully represents the fluorination in this temperature range. The rate control step is identified by examining the rate constants of the model for 300-1,800degC. For temperature range up to 900degC, the fluorination reaction is rate controlling. For over 900degC, both mechanisms of the mass transfer of fluorine and the fluorination reaction control the rate of the fluorination. With further increase of the temperature, however, the fluorination reaction becomes so fast that the mass transfer of fluorine eventually controls the rate of the fluorination. (author)

Synergistic effect of fluorination on molecular energy level modulation in highly efficient photovoltaic polymers.

Science.gov (United States)

Zhang, Maojie; Guo, Xia; Zhang, Shaoqing; Hou, Jianhui

2014-02-01

The synergistic effect of fluorination on molecular energy level modulation is realized by introducing fluorine atoms onto both the donor and the acceptor moieties in a D-A polymer, and as a result, the polymer solar cell device based on the trifluorinated polymer, PBT-3F, shows a high efficiency of 8.6%, under illumination of AM 1.5G, 100 mW cm(-) (2) . © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of nano-SiO{sub 2} modified fluorine-containing polyacrylate emulsifier-free emulsion

Energy Technology Data Exchange (ETDEWEB)

Zhou, Jianhua, E-mail: zhoujianh@21cn.com [College of Resource and Environment, Shaanxi University of Science and Technology, Xi’an 710021 (China); Shaanxi Research Institute of Agricultural Products Processing Technology, Xi’an 710021 (China); Chen, Xin; Duan, Hao; Ma, Jianzhong; Ma, Yurong [College of Resource and Environment, Shaanxi University of Science and Technology, Xi’an 710021 (China)

2015-03-15

Graphical abstract: Nano-SiO{sub 2} modified fluorine-containing polyacrylate emulsifier-free emulsion was synthesized by emulsifier-free emulsion polymerization and sol–gel process using ethyl silicate as precursor for nano-SiO{sub 2}. - Highlights: • Nano-SiO{sub 2} modified fluorine-containing polyacrylate emulsifier-free emulsion was successfully synthesized by emulsion polymerization using surfmer and sol–gel process. • The contact angle results showed that the finished fabric had an excellent water and oil repellency. • The nano-SiO{sub 2} modified fluorine-containing polyacrylate emulsifier-free emulsion proved to be highly solvent-resistant and water-resistant. • The transmission electron microscopy (TEM) indicated that the nano-SiO{sub 2} presented on the surface of latex particles. • The atomic force microscope (AFM) and energy dispersive X-ray spectrometer (EDX) confirmed that the hybrid film had a rough surface and the organic fluorine segment could migrate onto the film–air interface. - Abstract: Nano-SiO{sub 2} modified fluorine-containing polyacrylate emulsifier-free emulsion, consisting of methyl methacrylate, butyl acrylate, dodecafluoroheptyl methacrylate and ethyl silicate, was successfully synthesized by emulsion polymerization using surfmer and sol–gel process. When increasing ethyl silicate content, the latex centrifugal stability decreased, and the latex particle size increased. The contact angle results showed that the finished fabric had an excellent water and oil repellency. Furthermore, compared with fluorine-containing polyacrylate emulsifier-free emulsion, the obtained nano-SiO{sub 2} modified fluorine-containing polyacrylate emulsifier-free emulsion proved to be highly solvent-resistant and water-resistant. In addition, the transmission electron microscopy (TEM) indicated that the nano-SiO{sub 2} presented on the surface of latex particles. The atomic force microscope (AFM) and energy dispersive X-ray spectrometer

Fluorinated Phosphorene: Electrochemical Synthesis, Atomistic Fluorination, and Enhanced Stability.

Science.gov (United States)

Tang, Xian; Liang, Weiyuan; Zhao, Jinlai; Li, Zhongjun; Qiu, Meng; Fan, Taojian; Luo, Crystal Shaojuan; Zhou, Ye; Li, Yu; Guo, Zhinan; Fan, Dianyuan; Zhang, Han

2017-12-01

Phosphorene has attracted great interest due to its unique electronic and optoelectronic properties owing to its tunable direct and moderate band-gap in association with high carrier mobility. However, its intrinsic instability in air seriously hinders its practical applications, and problems of technical complexity and in-process degradation exist in currently proposed stabilization strategies. A facile pathway in obtaining and stabilizing phosphorene through a one-step, ionic liquid-assisted electrochemical exfoliation and synchronous fluorination process is reported in this study. This strategy enables fluorinated phosphorene (FP) to be discovered and large-scale, highly selective few-layer FP (3-6 atomic layers) to be obtained. The synthesized FP is found to exhibit unique morphological and optical characteristics. Possible atomistic fluorination configurations of FP are revealed by core-level binding energy shift calculations in combination with spectroscopic measurements, and the results indicate that electrolyte concentration significantly modulates the fluorination configurations. Furthermore, FP is found to exhibit enhanced air stability thanks to the antioxidation and antihydration effects of the introduced fluorine adatoms, and demonstrate excellent photothermal stability during a week of air exposure. These findings pave the way toward real applications of phosphorene-based nanophotonics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fluorine Based Superhydrophobic Coatings

Directory of Open Access Journals (Sweden)

Jean-Denis Brassard

2012-05-01

Full Text Available Superhydrophobic coatings, inspired by nature, are an emerging technology. These water repellent coatings can be used as solutions for corrosion, biofouling and even water and air drag reduction applications. In this work, synthesis of monodispersive silica nanoparticles of ~120 nm diameter has been realized via Stöber process and further functionalized using fluoroalkylsilane (FAS-17 molecules to incorporate the fluorinated groups with the silica nanoparticles in an ethanolic solution. The synthesized fluorinated silica nanoparticles have been spin coated on flat aluminum alloy, silicon and glass substrates. Functionalization of silica nanoparticles with fluorinated groups has been confirmed by Fourier Transform Infrared spectroscopy (FTIR by showing the presence of C-F and Si-O-Si bonds. The water contact angles and surface roughness increase with the number of spin-coated thin films layers. The critical size of ~119 nm renders aluminum surface superhydrophobic with three layers of coating using as-prepared nanoparticle suspended solution. On the other hand, seven layers are required for a 50 vol.% diluted solution to achieve superhydrophobicity. In both the cases, water contact angles were more than 150°, contact angle hysteresis was less than 2° having a critical roughness value of ~0.700 µm. The fluorinated silica nanoparticle coated surfaces are also transparent and can be used as paint additives to obtain transparent coatings.

Reactive flow analysis with fluorine thermal dissociation in a FLUOREX flame reactor

International Nuclear Information System (INIS)

Ohtsuka, Masaya; Tagawa, Hisato; Sasahira, Akira; Hoshino, Kuniyoshi; Kawamura, Fumio; Homma, Shunji; Amano, Osamu

2004-01-01

A reactive flow analysis method for flame reactors of the FLUOREX (Hybrid Process of Fluoride Volatility and Solvent Extraction) method was been developed. Transport equations for UO 2 /PuO 2 mixed particles were formulated in the Lagrangian framework and several fluid/particles interactions were modeled using mass, momentum and energy exchanges through surface chemical reactions, forces and heat transfers. The coal combustion model was modified without devolatilization and the char burnout model was replaced by the UO 2 /PuO 2 fluorination model. Overall reaction rates were calculated using the combined model of the surface reaction rate and the diffusion rate of F2 and F. Fluid flows were modeled through incompressible flows using the k-ε turbulent model in the Euler framework. A cylindrical flame reactor (φ 80 mm x 500mm was analyzed where 99%UO 2 +1%PuO 2 mixed particles were injected with Ar and 5% excess F 2 flow. The average particle diameter was 4 μm and the flow rate was 300 g/h. The fluorination reaction of PuO 2 was limited through fluorine molecular reaction but was accelerated due to fluorine thermal dissociation. The simulated corresponded to the experimental result in that both UO 2 and PuO 2 were almost completely fluorinated. (author)

Probing plasma fluorinated graphene via spectromicroscopy.

Science.gov (United States)

Struzzi, C; Scardamaglia, M; Reckinger, N; Sezen, H; Amati, M; Gregoratti, L; Colomer, J-F; Ewels, C; Snyders, R; Bittencourt, C

2017-11-29

Plasma fluorination of graphene is studied using a combination of spectroscopy and microscopy techniques, giving insight into the yield and fluorination mechanism for functionalization of supported graphene with both CF 4 and SF 6 gas precursors. Ion acceleration during fluorination is used to probe the effect on grafting functionalities. Adatom clustering, which occurs with CF 4 plasma treatment, is suppressed when higher kinetic energy is supplied to the ions. During SF 6 plasma functionalization, the sulfur atoms tend to bond to bare copper areas instead of affecting the graphene chemistry, except when the kinetic energy of the ions is restricted. Using scanning photoelectron microscopy, with a 100 nm spatial resolution, the chemical bonding environment is evaluated in the fluorinated carbon network at selected regions and the functionalization homogeneity is controlled in individual graphene flakes.

Enhanced nanoscale friction on fluorinated graphene.

Science.gov (United States)

Kwon, Sangku; Ko, Jae-Hyeon; Jeon, Ki-Joon; Kim, Yong-Hyun; Park, Jeong Young

2012-12-12

Atomically thin graphene is an ideal model system for studying nanoscale friction due to its intrinsic two-dimensional (2D) anisotropy. Furthermore, modulating its tribological properties could be an important milestone for graphene-based micro- and nanomechanical devices. Here, we report unexpectedly enhanced nanoscale friction on chemically modified graphene and a relevant theoretical analysis associated with flexural phonons. Ultrahigh vacuum friction force microscopy measurements show that nanoscale friction on the graphene surface increases by a factor of 6 after fluorination of the surface, while the adhesion force is slightly reduced. Density functional theory calculations show that the out-of-plane bending stiffness of graphene increases up to 4-fold after fluorination. Thus, the less compliant F-graphene exhibits more friction. This indicates that the mechanics of tip-to-graphene nanoscale friction would be characteristically different from that of conventional solid-on-solid contact and would be dominated by the out-of-plane bending stiffness of the chemically modified graphene. We propose that damping via flexural phonons could be a main source for frictional energy dissipation in 2D systems such as graphene.

Synthesis of Fluorinated Graphene/CoAl-Layered Double Hydroxide Composites as Electrode Materials for Supercapacitors.

Science.gov (United States)

Peng, Weijun; Li, Hongqiang; Song, Shaoxian

2017-02-15

CoAl-layered double hydroxide/fluorinated graphene (CoAl-LDH/FGN) composites were fabricated via a two-step hydrothermal method. The synthesized CoAl-LDH/FGN composites have been characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and electrochemical measurements. The results indicated that the fluorinated carbon with various configuration forms were grafted onto the framework of graphene, and the C-F bond configuration and fluorine content could be tuned by the fluorination time. Most of semi-ionic C-F bonds were formed at an appropriate fluorination time and, then, converted into fluorine rich surface groups (such as CF 2 , CF 3 , etc.) which were electrochemically inactive as the fluorination time prolonged. Moreover, the CoAl-LDH/FGN composites prepared at the optimal fluorination time exhibited the highest specific capacitance (1222 F/g at 1 A/g), the best rate capability, and the most stable capacitance retention, which offered great promise as electrode materials for supercapacitors.

Mechanism in determining pretilt angle of liquid crystals aligned on fluorinated copolymer films

Energy Technology Data Exchange (ETDEWEB)

Wu, Hsin-Ying; Wang, Chih-Yu; Lin, Chia-Jen; Pan, Ru-Pin [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan 30010 (China); Lin, Song-Shiang; Lee, Chein-Dhau [Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan 31040 (China); Kou, Chwung-Shan, E-mail: rpchao@mail.nctu.edu.t [Department of Physics, National Tsing Hua University, Hsinchu, Taiwan 30013 (China)

2009-08-07

This work explores the surface treatment of copolymer materials with fluorinated carbonyl groups in various mole fractions by ultraviolet irradiation and ion-beam (IB) bombardment and its effect on liquid crystal (LC) surface alignments. X-ray photoemission spectroscopic analysis confirms that the content of the grafted CF{sub 2} side chains dominates the pretilt angle. A significant increase in oxygen content is responsible for the increase in the polar surface energy during IB treatment. Finally, the polar component of the surface energy dominates the pretilt angle of the LCs.

Mechanism in determining pretilt angle of liquid crystals aligned on fluorinated copolymer films

International Nuclear Information System (INIS)

Wu, Hsin-Ying; Wang, Chih-Yu; Lin, Chia-Jen; Pan, Ru-Pin; Lin, Song-Shiang; Lee, Chein-Dhau; Kou, Chwung-Shan

2009-01-01

This work explores the surface treatment of copolymer materials with fluorinated carbonyl groups in various mole fractions by ultraviolet irradiation and ion-beam (IB) bombardment and its effect on liquid crystal (LC) surface alignments. X-ray photoemission spectroscopic analysis confirms that the content of the grafted CF 2 side chains dominates the pretilt angle. A significant increase in oxygen content is responsible for the increase in the polar surface energy during IB treatment. Finally, the polar component of the surface energy dominates the pretilt angle of the LCs.

Modes of occurrence of fluorine in the Late Paleozoic No. 6 coal from the Haerwusu Surface Mine, Inner Mongolia, China

Energy Technology Data Exchange (ETDEWEB)

Xibo Wang; Shifeng Dai; Yingying Sun; Dan Li; Weiguo Zhang; Yong Zhang; Yangbing Luo [China University of Mining and Technology, Beijing (China). State Key Laboratory of Coal Resources and Safe Mining

2011-01-15

The No. 6 coal from the Haerwusu Surface Mine, Inner Mongolia, China, is enriched in Al and Ga, which are valuable metal resources that could be extracted from fly ash. However, fluorine in the coal is unusually high (mean 286 {mu}g/g) and potentially toxic to the environment in the extraction process. In this paper, a sequential extraction/density separation procedure (SE/DS) was designed to examine the modes of occurrence of fluorine in the coal. The results show that fluorine extracted in distilled water, NH{sub 4}Ac (1 mol/l), and HCl (0.5%) leachates is low, and that in sulfide fraction is below the detection limit. The organic and silicate associations are inferred to account for more than 90% of the total fluorine in the coal. Boehmite and kaolinite are prime carriers of fluorine (the fluorine content in silicate fraction of the boehmite-enriched sample H-14 is up to 1906 {mu}g/g, and that of the kaolinite-enriched sample H-29 is 384 {mu}g/g). In bench samples H-2 and H-3, a minor amount of fluorine is related to goyazite. The relationship between fluorine and boehmite indicates that they were probably derived from the sediment source region, the weathered bauxite of the uplifted Benxi formation. 29 refs., 7 figs., 3 tabs.

Improving Photoconductance of Fluorinated Donors with Fluorinated Acceptors

Energy Technology Data Exchange (ETDEWEB)

Garner, Logan E.; Larson, Bryon; Oosterhout, Stefan; Owczarczyk, Zbyslaw; Olson, Dana C.; Kopidakis, Nikos; Boltalina, Olga V.; Strauss, Steven H.; Braunecker, Wade A.

2016-11-21

This work investigates the influence of fluorination of both donor and acceptor materials on the generation of free charge carriers in small molecule donor/fullerene acceptor BHJ OPV active layers. A fluorinated and non-fluorinated small molecule analogue were synthesized and their optoelectronic properties characterized. The intrinsic photoconductance of blends of these small molecule donors was investigated using time-resolved microwave conductivity. Blends of the two donor molecules with a traditional non-fluorinated fullerene (PC70BM) as well as a fluorinated fullerene (C60(CF3)2-1) were investigated using 5% and 50% fullerene loading. We demonstrate for the first time that photoconductance in a 50:50 donor:acceptor BHJ blend using a fluorinated fullerene can actually be improved relative to a traditional non-fluorinated fullerene by fluorinating the donor molecule as well.

Relationship between microhardness and fluorine contents on tooth enamel determined by PIGE analysis

International Nuclear Information System (INIS)

Ma, D.S.; Paik, D.I.; Park, D.Y.; Moon, H.S.; Chang, Y.I.; Kim, J.B.

1997-01-01

The remineralization effect of fluoride has been measured by surface microhardness on tooth enamel. The purpose of this study was to investigate the relationship between microhardness and fluorine concentration on tooth enamel. Twelve sound bovine enamel specimens were prepared and immersed in 0.05% NaF solution for 1, 3, 6, 24 and 36 hours, respectively. The concentration of fluorine in specimens were measured by PIGE analysis and surface microhardness of each specimen was measured by surface microhardness tester. Fluorine concentration was increased by immersing time. There was no change in microhardness of each specimen by fluorine content. The results of this study suggest that there was no relationship between the fluorine concentration and surface microhardness in sound tooth enamel. PIGE analysis can be used effectively to assess the remineralization effect of fluorine content in tooth enamel. (author)

Hydrolytically stable fluorinated metal-organic frameworks for energy-efficient dehydration

KAUST Repository

Cadiau, Amandine; Belmabkhout, Youssef; Adil, Karim; Bhatt, Prashant; Pillai, Renjith S.; Shkurenko, Aleksander; Martineau-Corcos, Charlotte; Maurin, Guillaume; Eddaoudi, Mohamed

2017-01-01

fluorinated metal-organic framework, AlFFIVE-1-Ni (KAUST-8), with a periodic array of open metal coordination sites and fluorine moieties within the contracted square-shaped one-dimensional channel. This material selectively removed water vapor from gas

Effects of fluorine-based plasma treatment and thermal annealing on high-Al content AlGaN Schottky contact

International Nuclear Information System (INIS)

Liu Fang; Qin Zhixin

2016-01-01

Fluorine plasma treatment was used prior to the Schottky metal deposition on the undoped Al 0.45 Ga 0.55 N, which aimed at the solar-blind wavelength. After fluorine plasma treatment and before depositing the Ni/Au Schottky, the samples were thermal annealed in the N 2 gas at 400 °C. The reverse leakage current density of Al 0.45 Ga 0.55 N Schottky diode was reduced by 2 orders of magnitude at −10 V. The reverse leakage current density was reduced by 3 orders of magnitude after thermal annealing. Further capacitance–frequency analysis revealed that the fluorine-based plasma treatment reduces the surface states of AlGaN by one order of magnitude at different surface state energies. The capacitance–frequency analysis also proved that the concentration of carriers in AlGaN top is reduced through fluorine plasma treatment. (paper)

Highly sensitive and selective determination of fluorine ion by graphene oxide/nanogold resonance Rayleigh scattering-energy transfer analytical platform.

Science.gov (United States)

Liang, Aihui; Peng, Jing; Liu, Qingye; Wen, Guiqing; Lu, Zhujun; Jiang, Zhiliang

2015-08-15

In pH 4.0 acetate buffer solution, fluorine ions react with fluorine reagent (FR) and La(III) to generate blue ternary complex that exhibited strong absorption at about 370 nm. Upon addition of graphene oxide/nanogold (GO/NG) as resonance Rayleigh scattering (RRS) spectral probe with strong RRS peak at 370 nm, the color changed to gray, and the RRS intensity decreased with the increase of fluorine ion concentration due to the RRS energy transfer (RRSET) from GO/NG to the complex. Under the selected condition, the decreased RRS peak ΔI370 nm was linear to fluorine ion concentration in the range of 6.0 × 10(-8)-1.3 × 10(-5)mol/L, with a detection limit of 3.0 × 10(-8)mol/L F(-). This RRSET method was applied to the analysis of fluorine in toothpaste and water samples, with satisfactory results. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fluorinated Graphene Prepared by Direct Fluorination of N, O-Doped Graphene Aerogel at Different Temperatures for Lithium Primary Batteries

Directory of Open Access Journals (Sweden)

Xu Bi

2018-06-01

Full Text Available Fluorinated graphene (FG has been a star material as a new derivative of graphene. In this paper, a series of fluorinated graphene materials are prepared by using N, O-doped graphene aerogel as precursor via a direct fluorination method, and the effect of fluorination temperature on the FG structure is investigated. The prepared FG samples are systematically characterized by scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. It is found that the structure of FG, including features such as layer size, chemical composition, chemical bond state of the component elements, etc., is significantly related to the fluorination temperature. With the change of the fluorination temperature, fluorine atoms enter the graphene framework by a substitution process of the N, O-containing groups, including residual phenol, ether, carbonyl groups, or C–N groups, and the addition to CC bonds, subsequently forming a fluoride with different fluorine contents. The fluorine content increases as the fluorination temperature increases from 200 °C to 300 °C, but decreases at a fluorination temperature of 350 °C due to the decomposition of the fluorinated graphene. The prepared FG samples are used as cathode material for lithium primary batteries. The FG sample prepared at 300 °C gives a high specific capacity of 632 mAh g−1 and a discharge plateau of 2.35 V at a current density of 10 mA g−1, corresponding to a high energy density of 1485 Wh kg−1.

Silicon structuring by etching with liquid chlorine and fluorine precursors using femtosecond laser pulses

International Nuclear Information System (INIS)

Radu, C.; Simion, S.; Zamfirescu, M.; Ulmeanu, M.; Enculescu, M.; Radoiu, M.

2011-01-01

The aim of this study is to investigate the micrometer and submicrometer scale structuring of silicon by liquid chlorine and fluorine precursors with 200 fs laser pulses working at both fundamental (775 nm) and frequency doubled (387 nm) wavelengths. The silicon surface was irradiated at normal incidence by immersing the Si (111) substrates in a glass container filled with liquid chlorine (CCl 4 ) and fluorine (C 2 Cl 3 F 3 ) precursors. We report that silicon surfaces develop an array of spikes with single step irradiation processes at 775 nm and equally at 387 nm. When irradiating the Si surface with 400 pulses at 330 mJ/cm 2 laser fluence and a 775 nm wavelength, the average height of the formed Si spikes in the case of fluorine precursors is 4.2 μm, with a full width at half maximum of 890 nm. At the same irradiation wavelength chlorine precursors develop Si spikes 4 μm in height and with a full width at half maximum of 2.3 μm with irradiation of 700 pulses at 560 mJ/cm 2 laser fluence. Well ordered areas of submicrometer spikes with an average height of about 500 nm and a width of 300 nm have been created by irradiation at 387 nm by chlorine precursors, whereas the fluorine precursors fabricate spikes with an average height of 700 nm and a width of about 200 nm. Atomic force microscopy and scanning electron microscopy of the surface show that the formation of the micrometer and sub-micrometer spikes involves a combination of capillary waves on the molten silicon surface and laser-induced etching of silicon, at both 775 nm and 387 nm wavelength irradiation. The energy-dispersive x-ray measurements indicate the presence of chlorine and fluorine precursors on the structured surface. The fluorine precursors create a more ordered area of Si spikes at both micrometer and sub-micrometer scales. The potential use of patterned Si substrates with gradient topography as model scaffolds for the systematic exploration of the role of 3D micro/nano morphology on cell

Depth profiling of fluorine-doped diamond-like carbon (F-DLC) film: Localized fluorine in the top-most thin layer can enhance the non-thrombogenic properties of F-DLC

Energy Technology Data Exchange (ETDEWEB)

Hasebe, Terumitsu [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Department of Radiology, Tachikawa Hospital, 4-2-22, Nishiki-cho, Tachikawa, Tokyo 190-8531 (Japan)], E-mail: teru_hasebe@hotmail.com; Nagashima, So [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Kamijo, Aki [Department of Transfusion Medicine, the University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Yoshimura, Taichi; Ishimaru, Tetsuya; Yoshimoto, Yukihiro; Yohena, Satoshi; Kodama, Hideyuki; Hotta, Atsushi [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Takahashi, Koki [Department of Transfusion Medicine, the University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Suzuki, Tetsuya [Center for Science of Environment, Resources and Energy, Keio University Faculty of Science and Technology, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522 (Japan)

2007-12-03

Fluorine-doped diamond-like carbon (F-DLC) has recently drawn a great deal of attention as a more non-thrombogenic coating than conventional DLC for blood-contacting medical devices. We conducted quantitative depth profiling of F-DLC film by X-ray photoelectron spectroscopy (XPS) in order to elucidate the effects of fluorine and fluorine distribution in F-DLC film in connection with the prevention of surface blood adhesion. F-DLC films were prepared on silicon substrates using the radio frequency plasma enhanced chemical vapor deposition method, and the thickness of films was {approx} 50 nm. 50-nm-thick F-DLC film samples were etched at 10-nm thickness intervals using argon plasma, and each surface was examined by XPS. Thereafter, each etched film layer was incubated with platelet-rich plasma isolated from human whole blood, and the platelet-covered area per unit area was evaluated for each surface. XPS spectra showed the localization of doped fluorine in the top-most thin layer of the film. Platelet-covered areas represented progressively larger portions of the surfaces of deeper etched layers, corresponding to the decreasing fluorine content in such sample surfaces. These results indicate that the localized fluorine in the top-most thin layer is one of the key factors in the promotion of the non-thrombogenicity of F-DLC film.

Fluorine atom subsurface diffusion and reaction in photoresist

International Nuclear Information System (INIS)

Greer, Frank; Fraser, D.; Coburn, J.W.; Graves, David B.

2003-01-01

Kinetic studies of fluorine and deuterium atoms interacting with an OiR 897 10i i-line photoresist (PR) are reported. All experiments were conducted at room temperature. Films of this PR were coated on quartz-crystal microbalance (QCM) substrates and exposed to alternating fluxes of these atoms in a high vacuum apparatus. Mass changes of the PR were observed in situ and in real time during the atom beam exposures using the QCM. A molecular-beam sampled differentially pumped quadrupole mass spectrometer (QMS) was used to measure the species desorbing from the PR surface during the F and D atom exposures. During the D atom exposures, hydrogen abstraction and etching of the PR was observed, but no DF formation was detected. However, during the F atom exposures, the major species observed to desorb from the surface was DF, formed from fluorine abstraction of deuterium from the photoresist. No evidence of film etching or fluorine self-abstraction was observed. The film mass increased during F atom exposure, evidently due to the replacement of D by F in the film. The rate of DF formation and mass uptake were both characterized by the same kinetics: An initially rapid step declining exponentially with time (e -t/τ ), followed by a much slower step following inverse square root of time (t -1/2 ) kinetics. The initially rapid step was interpreted as surface abstraction of D by F to form DF, which desorbs, with subsequent F impacting the surface inserted into surface C dangling bonds. The slower step was interpreted as F atoms diffusing into the fluorinated photoresist, forming DF at the boundary of the fluorinated carbon layer. The t -1/2 kinetics of this step are interpreted to indicate that F diffusion through the fluorinated carbon layer is much slower than the rate of F abstraction of D to form DF, or the rate of F insertion into the carbon dangling bonds left behind after DF formation. A diffusion-limited growth model was formulated, and the model parameters are

Influence of fluorine substitution on the morphology and structure of hydroxyapatite nanocrystals prepared by hydrothermal method

International Nuclear Information System (INIS)

Joseph Nathanael, A.; Mangalaraj, D.; Hong, S.I.; Masuda, Y.; Rhee, Y.H.; Kim, H.W.

2013-01-01

Hydroxyapatite (HAp) nanocrystals with different levels of fluorine substitution (P/F = 0, 6, 4 and 2) on the OH sites were produced via hydrothermal method. The fluorine substitution was found to alter the morphology of crystals appreciably. The aspect ratio and the crystallinity of HAp crystals increased with increasing fluorine substitution. The presence of broad ring and hallow ring patterns in electron diffraction suggests the low-crystalline nature of HAp crystals. With increasing fluorine substitution, the diffraction patterns exhibited discrete rings and numerous diffraction spots, implying the increased crystallinity. Raman spectra from the HAp nanoparticles also support the less-crystalline nature of the pristine HAp and the enhanced crystallization by fluorine substitution. In HAp crystals processed with no fluorine substitution, surface energy and planar Ca 2+ density are less sensitive to the crystallographic orientation because of its low-crystalline nature, favoring equi-axed or slightly elongated particles. The addition of fluorine apparently increased the crystallinity, enhancing the orientation dependent growth and accordingly the aspect ratio. Osteoblast proliferation was observed to be enhanced by fluorine substitution in HAp. In vitro biological data support that the excellent osteoblastic cell viability and functional activity of the fluoridated apatite. -- Highlights: ► Fluorapatite nanorods were produced hydrothermally with different fluorine content. ► Fluorine substitution was found to alter the morphology of crystals appreciably. ► It enhances the crystallinity, orientation dependent growth and hence aspect ratio. ► In vitro cellular analysis shows excellent cell viability of the fluorapatite.

Surface properties and aggregate morphology of partially fluorinated carboxylate-type anionic gemini surfactants.

Science.gov (United States)

Yoshimura, Tomokazu; Bong, Miri; Matsuoka, Keisuke; Honda, Chikako; Endo, Kazutoyo

2009-11-01

Three anionic homologues of a novel partially fluorinated carboxylate-type anionic gemini surfactant, N,N'-di(3-perfluoroalkyl-2-hydroxypropyl)-N,N'-diacetic acid ethylenediamine (2C(n)(F) edda, where n represents the number of carbon atoms in the fluorocarbon chain (4, 6, and 8)) were synthesized. In these present gemini surfactants, the relatively small carboxylic acid moieties form hydrophilic head groups. The surface properties or structures of the aggregates of these surfactants are strongly influenced by the nonflexible fluorocarbons and small head groups; this is because these surfactants have a closely packed molecular structure. The equilibrium surface tension properties of these surfactants were measured at 298.2K for various fluorocarbon chain lengths. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain lengths for 2C(n)(F) edda (n=4, 6, and 8) showed a minimum for n=6. Furthermore, the lowest surface tension of 2C(6)(F) edda at the cmc was 16.4mNm(-1). Such unique behavior has not been observed even in the other fluorinated surfactants. Changes in the shapes and sizes of these surfactant aggregate with concentration were investigated by dynamic light scattering and transmission electron microscopy (TEM). The TEM micrographs showed that in an aqueous alkali solution, 2C(n)(F) edda mainly formed aggregates with stringlike (n=4), cagelike (n=6), and distorted bilayer structures (n=8). The morphological changes in the aggregates were affected by the molecular structure composed of nonflexible fluorocarbon chains and flexible hydrocarbon chains.

The metal-carbon-fluorine system for improving hydrogen storage by using metal and fluorine with different levels of electronegativity

Energy Technology Data Exchange (ETDEWEB)

Im, Ji Sun; Lee, Young-Seak [Department of Fine Chemical Engineering and Applied Chemistry, BK21-E2M, Chungnam National University, Daejeon 305-764 (Korea); Park, Soo-Jin [Department of Chemistry, Inha University, Incheon 402-751 (Korea)

2009-02-15

In order to improve the capacity of hydrogen storage using activated carbon nanofibers, metal and fluorine were introduced into the activated carbon nanofibers by electrospinning, heat treatment, and direct fluorination. The pore structure of the samples was developed by the KOH activation process and investigated using nitrogen isotherms and micropore size distribution. The specific surface area and total pore volume approached 2800 m{sup 2}/g and 2.7 cc/g, respectively. Because of the electronegativity gap between the two elements (metal and fluorine), the electron of a hydrogen molecule can be attracted to one side. This reaction effectively guides the hydrogen molecule into the carbon nanofibers. The amount of hydrogen storage was dramatically increased in this metal-carbon-fluorine system; hydrogen content was as high as 3.2 wt%. (author)

Synthesis of fluorine- doped silica-coating by fluorosilane nanofluid to ultrahydrophobic and ultraoleophobic surface

Science.gov (United States)

Saboori, R.; Azin, R.; Osfouri, Sh; Sabbaghi, S.; Bahramian, A.

2017-10-01

Liquid repellency treatment has many applications in various sectors including oil and gas reservoirs and self-cleaning surfaces. In this study, effect of silica, fluorine-doped silica and fluorine-doped silica-coating by fluorosilane nanofluid on ultrahydrophobic and ultraoleophobic surface of carbonate and sandstone rock were investigated. The nanoparticles were synthesized by sol-gel method and characterized using XRD, FTIR, FESEM and DLS and nanofluid was prepared. F-SiO2-F nanoparticle was adsorbed on surface of rocks and confirmed by FESEM and EDXA. Effect of nanofluid on wettability was investigated by measuring contact angles of water, crude oil, condensate, n-decane and ethylene glycol in air and stability of ultrahydrophobic and ultraoleophobic was investigated. Results show that nanofluid (0.05 wt% of nanoparticle) changes contact angle from strongly liquid-wet to strongly gas-wet in all systems. The original contact angle of water, crude oil, condensate, n-decane and ethylene glycol were 37.95°, 0°, 0°, 0° and 0° for carbonate rock and 40.30°, 0°, 0°, 0° and 0° for sandstone rock which altered to 146.47°, 145.59°, 138.24°, 139.06° and 146.52° for carbonate rock and 160.01°, 151.40°, 131.85°, 140.27° and 151.70° for sandstone rock after treatment. The ultraoleophobic and ultrahydrophobic stability were  >48 h and 120 min.

Gold nanoparticles as markers for fluorinated surfaces containing embedded amide groups

Science.gov (United States)

Ballarin, Barbara; Barreca, Davide; Bertola, Maurizio; Cristina Cassani, Maria; Carraro, Giorgio; Maccato, Chiara; Mignani, Adriana; Nanni, Daniele; Parise, Chiara; Ranieri, Silvia

2018-05-01

Indium tin oxide (ITO) substrates were functionalized with fluoroalkylsilanes (FAS) having formula RFC(O)N(R)(CH2)3Si(OMe)3 (1, R = H, RF = C5F11; 2, R = CH3, RF = C5F11;3, R = H, RF = C3F7) and containing embedded amide moieties between the perfluoroalkyl chain and the syloxanic moiety. Subsequently, Au nanoparticle deposition (AuNP) onto the ITO-FAS functionalized surfaces was carried out by immersion into a solution of citrate-stabilized AuNP. The ITO-FAS and AuNP/ITO-FAS modified systems were characterized by various complementary techniques and compared with AuNP/ITO modified with RF(CH2)2Si(OEt)3 (4, RF = C6F13), free from functional groups between the fluorinated tail and the syloxanic moiety. The results showed that only ITO glasses modified with 1, 2 and 3 displayed an oleophobic, as well as hydrophobic, behaviour and that the AuNP Surface Coverage (SC %) directly depended on the fluoroalkylsilane nature with the following trend: 60% ITO-2 > 16% ITO-3 > 9% ITO-1 > 3% ITO-4. The obtained results revealed that, in organosilane 2, the presence of a methyl group on the amide nitrogen increases the steric hindrance in the rotation around the Nsbnd CO bond, resulting in the co-presence of two stable conformers in comparable amounts. Their co-presence in solution, combined with the lack of intermolecular Nsbnd H⋯OCsbnd N hydrogen bonds among the anchored molecules, has dramatic influences on the functionalized ITO, yielding a disorderedly packed coating able to accommodate a large quantity of AuNP. These results indicate that AuNP can act as excellent probes to evaluate the coating layer quality but, at the same time, it is possible to tune the gold loading on electroactive surfaces depending on the chemical structure of the used fluorinated silane.

Heterogeneous nucleation of protein crystals on fluorinated layered silicate.

Directory of Open Access Journals (Sweden)

Keita Ino

Full Text Available Here, we describe an improved system for protein crystallization based on heterogeneous nucleation using fluorinated layered silicate. In addition, we also investigated the mechanism of nucleation on the silicate surface. Crystallization of lysozyme using silicates with different chemical compositions indicated that fluorosilicates promoted nucleation whereas the silicates without fluorine did not. The use of synthesized saponites for lysozyme crystallization confirmed that the substitution of hydroxyl groups contained in the lamellae structure for fluorine atoms is responsible for the nucleation-inducing property of the nucleant. Crystallization of twelve proteins with a wide range of pI values revealed that the nucleation promoting effect of the saponites tended to increase with increased substitution rate. Furthermore, the saponite with the highest fluorine content promoted nucleation in all the test proteins regardless of their overall net charge. Adsorption experiments of proteins on the saponites confirmed that the density of adsorbed molecules increased according to the substitution rate, thereby explaining the heterogeneous nucleation on the silicate surface.

Influence of fluorine substitution on the morphology and structure of hydroxyapatite nanocrystals prepared by hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Joseph Nathanael, A., E-mail: ajosephnc@yahoo.com [Department of Nanomaterials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.com [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046 (India); Hong, S.I., E-mail: sihong@cnu.ac.kr [Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Masuda, Y. [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Rhee, Y.H.; Kim, H.W. [Department of Microbiology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2013-01-15

Hydroxyapatite (HAp) nanocrystals with different levels of fluorine substitution (P/F = 0, 6, 4 and 2) on the OH sites were produced via hydrothermal method. The fluorine substitution was found to alter the morphology of crystals appreciably. The aspect ratio and the crystallinity of HAp crystals increased with increasing fluorine substitution. The presence of broad ring and hallow ring patterns in electron diffraction suggests the low-crystalline nature of HAp crystals. With increasing fluorine substitution, the diffraction patterns exhibited discrete rings and numerous diffraction spots, implying the increased crystallinity. Raman spectra from the HAp nanoparticles also support the less-crystalline nature of the pristine HAp and the enhanced crystallization by fluorine substitution. In HAp crystals processed with no fluorine substitution, surface energy and planar Ca{sup 2+} density are less sensitive to the crystallographic orientation because of its low-crystalline nature, favoring equi-axed or slightly elongated particles. The addition of fluorine apparently increased the crystallinity, enhancing the orientation dependent growth and accordingly the aspect ratio. Osteoblast proliferation was observed to be enhanced by fluorine substitution in HAp. In vitro biological data support that the excellent osteoblastic cell viability and functional activity of the fluoridated apatite. -- Highlights: Black-Right-Pointing-Pointer Fluorapatite nanorods were produced hydrothermally with different fluorine content. Black-Right-Pointing-Pointer Fluorine substitution was found to alter the morphology of crystals appreciably. Black-Right-Pointing-Pointer It enhances the crystallinity, orientation dependent growth and hence aspect ratio. Black-Right-Pointing-Pointer In vitro cellular analysis shows excellent cell viability of the fluorapatite.

MODELLING OF KINETICS OF FLUORINE ADSORPTION ONTO MODIFIED DIATOMITE

Directory of Open Access Journals (Sweden)

VEACESLAV ZELENTSOV

2017-03-01

Full Text Available The paper presents kinetics modelling of adsorption of fluorine onto modified diatomite, its fundamental characteristics and mathematical derivations. Three models of defluoridation kinetics were used to fit the experimental results on adsorption fluorine onto diatomite: the pseudo-first order model Lagergren, the pseudo-second order model G. McKay and H.S. Ho and intraparticle diffusion model of W.J. Weber and J.C. Morris. Kinetics studies revealed that the adsorption of fluorine followed second-order rate model, complimented by intraparticle diffusion kinetics. The adsorption mechanism of fluorine involved three stages – external surface adsorption, intraparticle diffusion and the stage of equilibrium.

Fluorine

Science.gov (United States)

Hayes, Timothy S.; Miller, M. Michael; Orris, Greta J.; Piatak, Nadine M.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

after that time include the Nui Phao tungsten-fluorspar-bismuth-copper-gold deposit in northern Vietnam; the St. Lawrence project in Newfoundland, Canada, which is located in a well-known fluorspar district; the Bamianshan deposit, which is related to a strongly differentiated granite in northwestern Zhejiang Province, China, near some of that Province’s large, subalkaline-volcanic-related epithermal veins; and the Nokeng project in South Africa, which is also related to a strongly differentiated granite. Other deposits in northwestern Australia, Nevada (United States), Norway, South Africa, and Sweden have been identified and could be put into production within just a few years.Among undiscovered resources, an interesting possibility might be to produce a fluorine product from evaporitic, high-fluorine, high-pH sodium-carbonate brines like Lake Magadi (Kenya) and Lake Natron (Tanzania) in Africa’s Eastern Rift Valley. In addition, apparently conformable fluorspar deposits in tuffaceous limy lacustrine sediments, such as those in Italy, are likely to occur in similar young alkalic volcanic settings elsewhere in the world.Modern geophysical and geochemical exploration techniques have typically not been brought to bear in exploration for new fluorspar deposits, although such techniques are likely to be used in future exploration. The tendency for fluorine to dissolve in significant concentrations in water at low temperature allows both surface water and groundwater to be used as sampling media in geochemical exploration. Evolved granite-related fluorspar deposits may be particularly susceptible to geophysical exploration methods because crystalline rocks that form a basement to sedimentary sections can be approximately defined with gravity and magnetic methods, and magnetite-bearing skarns can be directly detected with magnetic surveys.Environmental considerations of fluorine mining focus especially on drinking water, where high fluorine concentrations can lead to

Production of low energy gamma rays by neutron interactions with fluorine for incident neutron energies between 0.1 and 20 MeV

International Nuclear Information System (INIS)

Morgan, G.L.; Dickens, J.K.

1975-06-01

Differential cross sections for the production of low-energy gamma rays (less than 240 keV) by neutron interactions in fluorine have been measured for neutron energies between 0.1 and 20 MeV. The Oak Ridge Electron Linear Accelerator was used as the neutron source. Gamma rays were detected at 92 0 using an intrinsic germanium detector. Incident neutron energies were determined by time-of-flight techniques. Tables are presented for the production cross sections of three gamma rays having energies of 96, 110, and 197 keV. (14 figures, 3 tables) (U.S.)

Proton Exchange Membrane Fuel Cell With Enhanced Durability Using Fluorinated Carbon As Electrocatalyst

Directory of Open Access Journals (Sweden)

Ahmad Yasser

2017-01-01

Full Text Available This study evaluates the fluorination of a carbon aerogel and its effects on the durability of the resulting electrocatalyst for Proton Exchange Membrane Fuel Cell (PEMFC. Fluorine has been introduced before or after platinum deposition. The different electrocatalysts are physico-chemically and electrochemically characterized, and the results discussed by comparison with commercial Pt/XC72 from E-Tek. The results demonstrate that the level of fluorination of the carbon aerogel can be controlled. The fluorination modifies the texture of the carbons by increasing the pore size and decreasing the specific surface area, but the textures remain appropriate for PEMFC applications. Two fluorination sites are observed, leading to both high covalent C-F bond and weakened ones, the quantity of which depends on whether the treatment is done before or after platinum deposition. The order of the different treatments is very important. The presence of platinum contributes to the fluorination mechanism, but leads to amorphous platinum rather inactive towards the Oxygen Reduction Reaction. Finally, a better durability was demonstrated for the fluorinated then platinized catalyst compared both to the same but not fluorinated catalyst and to the reference commercial material (based on the loss of the electrochemical real surface area after accelerated stress tests.

Fluorination of Boron-Doped Diamond Film Electrodes for Minimization of Perchlorate Formation.

Science.gov (United States)

Gayen, Pralay; Chaplin, Brian P

2017-08-23

This research investigated the effects of surface fluorination on both rates of organic compound oxidation (phenol and terephthalic acid (TA)) and ClO 4 - formation at boron-doped diamond (BDD) film anodes at 22 °C. Different fluorination methods (i.e., electrochemical oxidation with perfluorooctanoic acid (PFOA), radio frequency plasma, and silanization) were used to incorporate fluorinated moieties on the BDD surface, which was confirmed by X-ray photoelectron spectroscopy (XPS). The silanization method was found to be the most effective fluorination method using a 1H,1H,2H,2H-perfluorodecyltrichlorosilane precursor to form a self-assembled monolayer (SAM) on the oxygenated BDD surface. The ClO 4 - formation decreased from rates of 0.45 ± 0.03 mmol m -2 min -1 during 1 mM NaClO 3 oxidation and 0.28 ± 0.01 mmol m -2 min -1 during 10 mM NaCl oxidation on the BDD electrode to below detectable levels (layer on the BDD surface that inhibited charge transfer via steric hindrance and hydrophobic effects. The surface coverages and thicknesses of the fluorinated films controlled the charge transfer rates, which was confirmed by estimates of film thicknesses using XPS and density functional theory simulations. The aliphatic silanized electrode also showed very high stability during OH • production. Perchlorate formation rates were below the detection limit (<0.12 μmoles m -2 min -1 ) for up to 10 consecutive NaClO 3 oxidation experiments.

Photoemission studies of fluorine functionalized porous graphitic carbon

Science.gov (United States)

Ganegoda, Hasitha; Jensen, David S.; Olive, Daniel; Cheng, Lidens; Segre, Carlo U.; Linford, Matthew R.; Terry, Jeff

2012-03-01

Porous graphitic carbon (PGC) has unique properties desirable for liquid chromatography applications when used as a stationary phase. The polar retention effect on graphite (PREG) allows efficient separation of polar and non-polar solutes. Perfluorinated hydrocarbons however lack polarizabilty and display strong lipo- and hydrophobicity, hence common lipophilic and hydrophilic analytes have low partition coefficiency in fluorinated stationary phases. Attractive interaction between fluorinated stationary phase and fluorinated analytes results in strong retention compared to non-fluorinated analytes. In order to change the selectivities of PGC, it is necessary to develop a bonded PGC stationary phase. In this study, we have synthesized perfluorinated, PGC using hepatadecafluoro-1-iodooctane, under different temperature conditions. Surface functionalization of the raw material was studied using photoelectron spectroscopy (PES). Results indicate the existence of fluorine containing functional groups, -CF, -CF2 along with an intercalated electron donor species. Multiple oxygen functional groups were also observed, likely due to the presence of oxygen in the starting material. These oxygen species may be responsible for significant modifications to planer and tetrahedral carbon ratios.

Photoemission studies of fluorine functionalized porous graphitic carbon

Energy Technology Data Exchange (ETDEWEB)

Ganegoda, Hasitha; Olive, Daniel; Cheng, Lidens; Segre, Carlo U.; Terry, Jeff [Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Jensen, David S.; Linford, Matthew R. [Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602 (United States)

2012-03-01

Porous graphitic carbon (PGC) has unique properties desirable for liquid chromatography applications when used as a stationary phase. The polar retention effect on graphite (PREG) allows efficient separation of polar and non-polar solutes. Perfluorinated hydrocarbons however lack polarizabilty and display strong lipo- and hydrophobicity, hence common lipophilic and hydrophilic analytes have low partition coefficiency in fluorinated stationary phases. Attractive interaction between fluorinated stationary phase and fluorinated analytes results in strong retention compared to non-fluorinated analytes. In order to change the selectivities of PGC, it is necessary to develop a bonded PGC stationary phase. In this study, we have synthesized perfluorinated, PGC using hepatadecafluoro-1-iodooctane, under different temperature conditions. Surface functionalization of the raw material was studied using photoelectron spectroscopy (PES). Results indicate the existence of fluorine containing functional groups, -CF, -CF{sub 2} along with an intercalated electron donor species. Multiple oxygen functional groups were also observed, likely due to the presence of oxygen in the starting material. These oxygen species may be responsible for significant modifications to planer and tetrahedral carbon ratios.

Mechanical and Structural Properties of Fluorine-Ion-Implanted Boron Suboxide

OpenAIRE

Machaka, Ronald; Mwakikunga, Bonex W.; Manikandan, Elayaperumal; Derry, Trevor E.; Sigalas, Iakovos; Herrmann, Mathias

2012-01-01

Results on a systematic study on the effects of ion implantation on the near-surface mechanical and structural properties of boron suboxide (B 6O) prepared by uniaxial hot pressing are reviewed. 150keV fluorine ions at fluences of up to 5.0 × 10 16ions/cm 2 were implanted into the ultrahard ceramic material at room temperature and characterized using Raman spectroscopy, atomic force microscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Evidence of ion-beam-as...

Wettability alteration properties of fluorinated silica nanoparticles in liquid-loaded pores: An atomistic simulation

Energy Technology Data Exchange (ETDEWEB)

Sepehrinia, Kazem; Mohammadi, Aliasghar, E-mail: amohammadi@sharif.edu

2016-05-15

Highlights: • Properties of fluorinated silica nanoparticles were investigated in water or decane-loaded pores of mineral silica using molecular dynamics simulation. • The water or decane-loaded pores represent liquid bridging. • Addition of nanoparticles to liquid-loaded pores results in weakening of the liquid bridge. • The hydrophobicity of the pore wall increases in the presence of adsorbed fluorinated silica nanoparticles. - Abstract: Control over the wettability of reservoir rocks is of crucial importance for enhancing oil and gas recovery. In order to develop chemicals for controlling the wettability of reservoir rocks, we present a study of functionalized silica nanoparticles as candidates for wettability alteration and improved gas recovery applications. In this paper, properties of fluorinated silica nanoparticles were investigated in water or decane-loaded pores of mineral silica using molecular dynamics simulation. Trifluoromethyl groups as water and oil repellents were placed on the nanoparticles. Simulating a pore in the presence of trapped water or decane molecules leads to liquid bridging for both of the liquids. Adsorption of nanoparticles on the pore wall reduces the density of liquid molecules adjacent to the wall. The density of liquid molecules around the nanoparticles decreases significantly with increasing the number of trifluoromethyl groups on the nanoparticles’ surfaces. An increased hydrophobicity of the pore wall was observed in the presence of adsorbed fluorinated silica nanoparticles. Also, it is observed that increasing the number of the trifluoromethyl groups results in weakening of liquid bridges. Moreover, the free energy of adsorption on mineral surface was evaluated to be more favorable than that of aggregation of nanoparticles, which suggests nanoparticles adsorb preferably on mineral surface.

Wettability alteration properties of fluorinated silica nanoparticles in liquid-loaded pores: An atomistic simulation

International Nuclear Information System (INIS)

Sepehrinia, Kazem; Mohammadi, Aliasghar

2016-01-01

Highlights: • Properties of fluorinated silica nanoparticles were investigated in water or decane-loaded pores of mineral silica using molecular dynamics simulation. • The water or decane-loaded pores represent liquid bridging. • Addition of nanoparticles to liquid-loaded pores results in weakening of the liquid bridge. • The hydrophobicity of the pore wall increases in the presence of adsorbed fluorinated silica nanoparticles. - Abstract: Control over the wettability of reservoir rocks is of crucial importance for enhancing oil and gas recovery. In order to develop chemicals for controlling the wettability of reservoir rocks, we present a study of functionalized silica nanoparticles as candidates for wettability alteration and improved gas recovery applications. In this paper, properties of fluorinated silica nanoparticles were investigated in water or decane-loaded pores of mineral silica using molecular dynamics simulation. Trifluoromethyl groups as water and oil repellents were placed on the nanoparticles. Simulating a pore in the presence of trapped water or decane molecules leads to liquid bridging for both of the liquids. Adsorption of nanoparticles on the pore wall reduces the density of liquid molecules adjacent to the wall. The density of liquid molecules around the nanoparticles decreases significantly with increasing the number of trifluoromethyl groups on the nanoparticles’ surfaces. An increased hydrophobicity of the pore wall was observed in the presence of adsorbed fluorinated silica nanoparticles. Also, it is observed that increasing the number of the trifluoromethyl groups results in weakening of liquid bridges. Moreover, the free energy of adsorption on mineral surface was evaluated to be more favorable than that of aggregation of nanoparticles, which suggests nanoparticles adsorb preferably on mineral surface.

Multi-State Vibronic Interactions in Fluorinated Benzene Radical Cations.

Science.gov (United States)

Faraji, S.; Köppel, H.

2009-06-01

Conical intersections of potential energy surfaces have emerged as paradigms for signalling strong nonadiabatic coupling effects. An important class of systems where some of these effects have been analyzed in the literature, are the benzene and benzenoid cations, where the electronic structure, spectroscopy, and dynamics have received great attention in the literature. In the present work a brief overview is given over our theoretical treatments of multi-mode and multi-state vibronic interactions in the benzene radical cation and some of its fluorinated derivatives. The fluorobenzene derivatives are of systematic interest for at least two different reasons. (1) The reduction of symmetry by incomplete fluorination leads to a disappearance of the Jahn-Teller effect present in the parent cation. (2) A specific, more chemical effect of fluorination consists in the energetic increase of the lowest σ-type electronic states of the radical cations. The multi-mode multi-state vibronic interactions between the five lowest electronic states of the fluorobenzene radical cations are investigated theoretically, based on ab initio electronic structure data, and employing the well-established linear vibronic coupling model, augmented by quadratic coupling terms for the totally symmetric vibrational modes. Low-energy conical intersections, and strong vibronic couplings are found to prevail within the set of tilde{X}-tilde{A} and tilde{B}-tilde{C}-tilde{D} cationic states, while the interactions between these two sets of states are found to be weaker and depend on the particular isomer. This is attributed to the different location of the minima of the various conical intersections occurring in these systems. Wave-packet dynamical simulations for these coupled potential energy surfaces, utilizing the powerful multi-configuration time-dependent Hartree method are performed. Ultrafast internal conversion processes and the analysis of the MATI and photo-electron spectra shed new light

Introduction of oxygen vacancies and fluorine into TiO2 nanoparticles by co-milling with PTFE

International Nuclear Information System (INIS)

Senna, Mamoru; Šepelák, Vladimir; Shi, Jianmin; Bauer, Benjamin; Feldhoff, Armin; Laporte, Vincent; Becker, Klaus-Dieter

2012-01-01

Solid-state processes of introducing oxygen vacancies and transference of fluorine to n-TiO 2 nanoparticles by co-milling with poly(tetrafluoroethylene) (PTFE) powder were examined by diffuse reflectance spectroscopy (DRS) of UV, visual, near- and mid-IR regions, thermal analyses (TG-DTA), energy-dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The broad absorption peak at around 8800 cm −1 (1140 nm) was attributed to the change in the electronic states, viz. electrons trapped at the oxygen vacancies (Vo) and d–d transitions of titanium ions. Incorporation of fluorine into n-TiO 2 was concentrated at the near surface region and amounted to ca. 40 at% of the total fluorine in PTFE, after co-milling for 3 h, as confirmed by the F1s XPS spectrum. The overall atomic ratio, F/Ti, determined by EDXS was 0.294. By combining these analytical results, a mechanism of the present solid state processes at the boundary between PTFE and n-TiO 2 was proposed. The entire process is triggered by the partial oxidative decomposition of PTFE. This is accompanied by the abstraction of oxygen atoms from the n-TiO 2 lattices. Loss of the oxygen atoms results in the formation of the diverse states of locally distorted coordination units of titania, i.e. TiO 6−n Vo n , located at the near surface region. This leads subsequent partial ligand exchange between F and O, to incorporate fluorine preferentially to the near surface region of n-TiO 2 particles, where local non-crystalline states predominate. - Graphical abstract: Scheme of the reaction processes: (a) pristine mixture, (b) oxygen abstraction from TiO 2 and (c) fluorine migration from PTFE to TiO 2 . Highlights: Transfer of fluorine from PTFE to n-TiO 2 in a dry solid state process was confirmed. ► 40% of F in PTFE was incorporated to the near surface region of n-TiO 2 nanoparticles. ► The transfer process is

Fluorinated alkyne-derived monolayers on oxide-free silicon nanowires via one-step hydrosilylation

International Nuclear Information System (INIS)

Nguyen Minh, Quyen; Pujari, Sidharam P.; Wang, Bin; Wang, Zhanhua; Haick, Hossam; Zuilhof, Han; Rijn, Cees J.M. van

2016-01-01

Highlights: • Oxide-free H-terminated silicon nanowires undergo efficient surface modification by reaction with fluorinated 1-alkynes (HC≡C−(CH 2 ) 6 C 8 H 17−x F x ; x = 0–17). • These surface-modified Si NWs are chemically stable under range of conditions (including acid, base). • The surface coating yields efficient electrical passivation as demonstrated by a near-zero electrochemical activity of the surface. - Abstract: Passivation of oxide-free silicon nanowires (Si NWs) by the formation of high-quality fluorinated 1-hexadecyne-derived monolayers with varying fluorine content has been investigated. Alkyl chain monolayers (C 16 H 30−x F x ) with a varying number of fluorine substituents (x = 0, 1, 3, 9, 17) were attached onto hydrogen-terminated silicon (Si−H) surfaces with an effective one-step hydrosilylation. This surface chemistry gives well-defined monolayers on nanowires that have a cylindrical core–shell structure, as characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and static contact angle (SCA) analysis. The monolayers were stable under acidic and basic conditions, as well as under extreme conditions (such as UV exposure), and provide excellent surface passivation, which opens up applications in the fields of field effect transistors, optoelectronics and especially for disease diagnosis.

Saturation of the hydroxyapatite mineral phase using radioactive fluorine

International Nuclear Information System (INIS)

Flores de la Torre, J.A.; Badillo A, V.E.; Lopez D, F.A.

2005-01-01

With the purpose of knowing the Anion exchange capacity (CIA) of the hydroxyapatite mineral phase, marketed by BIO-RAD, becomes necessary to saturate the surface of the mineral with an anion specie that possesses a strong affinity by this solid as it is the case of the fluorine. Moreover it takes advantage that offers the radioactive tracer technique, using the radioactive isotope of the fluorine, 18 F, produced in the cyclotron of the UNAM. This saturation is obtained in terms of the quantity of retained fluorine (mmol/ 100 g) in the synthetic hydroxyapatite in function of the concentration of the solution of NaF that oscillates from 0.7 M up to 0.16 M to fixed values of pH of 9.2. Those results demonstrate that to this fixed pH value the saturation of the surface of the hydroxyapatite is achieved in approximately 30 mmol/ 100 g, using important concentrations of NaF that correspond to 0.14 M from now on. This result demonstrates the high capacity of the solid considered to retain considerable quantities of fluorine even to basic pH values. (Author)

Effects of fluorine on the human fetus

Energy Technology Data Exchange (ETDEWEB)

He, H.; Cheng, Z.S.; Liu, W.Q. [Huaxi Medical University, Huaxi (China)

2008-10-15

In an endemic fluorosis area, 16 fetuses that were delivered during their sixth to eighth month of gestation by means of artificial abortion were collected and studied. The results (compared to 10 control fetuses from a non-endemic area) show that fluorine levels in tissues are obviously high, especially in brain, calvarium, and femur. The activity of alkaline phosphatase in femur and kidney was raised. By observation of the ultrastructure of samples, the number of mitochondria, rough-surfaced endoplasmic reticulum, and free ribosome in neurons of cerebral cortex were reduced, and the rough-surfaced endoplasmic reticulum was obviously dilated. These findings indicate that the neurons of the cerebral cortex in the developing brain may be one of the targets of fluorine.

Fluorine concentration profiles in archaeological bone

International Nuclear Information System (INIS)

Coote, G.E.; Sparks, R.J.

1981-01-01

The nuclear microprobe at the Institute of Nuclear Sciences was applied to the measurement of radial concentration profiles of fluorine, in transverse slices of archaeological bone from humans, moas, and other animals. A beam of 2.5 MeV protons was focused to a rectangular spot 250 microns by 50 microns, traversed along a radial line 3mm long, and gamma rays of 5-7 MeV from the reaction 19 F(p, α#betta#) 16 O were detected in a large sodium iodide crystal. Bombardment caused no detectable loss of fluorine from the bone. Measured profiles display a wide variety of shapes and maximum concentrations. In bones which had been exposed to ground water the fluorine concentration usually increases from the centre towards the surface, sometimes by as much as a factor of eight. The concentration at the surface is usually in the range 0.2 to 1%, though in moa bone from a limestone cave it is only 0.025%. Once a quantitative method of analysis has been developed, based on the shape of the profile rather than its magnitude, these profiles might be useful for dating bone. In the meantime, they could be used to distinguish bones of different ages from a common site

Diagnosis of fluorine damage. II. Estimation of fluorine-containing emission by demonstration of the storage of fluorine in the cortex of trees

Energy Technology Data Exchange (ETDEWEB)

Lampadius, F

1960-01-01

The thorium titration method was employed for estimating the fluorine content of the cortex. The question as to what fluorine content in the bark is to be regarded as natural has not yet been exactly established. Various indications in the literature lead to the assumption that the storage in the bark of cortex of the trees from an area without fluorine-containing emissions gave <0.2 mg. F/100 ml. distillate in all samples. This fluorine content was initially taken as the limit for the natural fluorine content of the cortex. The investigation of the fluorine content of the cortex extended only to the bark and was calculated in mg. of F in 5 g. of air-dry ground bark. The results show a clear relation between the quantity of fluorine stored in the bark and the distance of the point of sampling from the source of emission and its disposition to it. With high fluorine emission and unfavorable wind conditions in the affected area, fluorine was found in considerable quantities in the bark at places quite a long way from the source of emission. The qualitative estimation of the fluorine content of gassed leaves and needles by the crystal precipitation method, and the quantitative estimation of the fluorine content of gassed bark by the thorium titration method led to results that were in good agreement, so it was possible in this way to define the area in which damage may occur with reliable accuracy.

Effect of amorphous fluorinated coatings on photocatalytic properties of anodized titanium surfaces

Energy Technology Data Exchange (ETDEWEB)

Persico, Federico [Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131, Milano (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy); Sansotera, Maurizio, E-mail: maurizio.sansotera@polimi.it [Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131, Milano (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy); Diamanti, Maria Vittoria [Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131, Milano (Italy); Magagnin, Luca; Venturini, Francesco; Navarrini, Walter [Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131, Milano (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy)

2013-10-31

The photocatalytic activity promoted by anodized titanium surfaces coated with different amorphous perfluoropolymers was evaluated. A copolymer between tetrafluoroethylene and perfluoro-4-trifluoromethoxy-1,3-dioxole and two perfluoropolyethers containing ammonium phosphate and triethoxysilane functionalities, respectively, were tested as coating materials. These coatings revealed good adhesion to the anodized titanium substrate and conferred to it both hydrophobicity and oleophobicity. The photocatalytic activity of the coating on anodized titanium was evaluated by monitoring the degradation of stearic acid via Infrared spectroscopy. The degradation rate of stearic acid was reduced but not set to zero by the presence of the fluorinated coatings, leading to the development of advanced functional coatings. The morphological variations of the coatings as a result of photocatalysis were also determined by atomic force microscopy. - Highlights: • Coated anodized titanium surfaces show a decreased wettability. • Evaluation of the stability of perfluorinated coatings towards photocatalysis. • Amorphous perfluorinated coatings do not hinder photocatalytic activity.

Compilation of Requirements for Safe Handling of Fluorine and Fluorine-Containing Products of Uranium Hexafluoride Conversion

Energy Technology Data Exchange (ETDEWEB)

Ferrada, J.J.

2000-04-03

Public Law (PL) 105-204 requires the U.S. Department of Energy to develop a plan for inclusion in the fiscal year 2000 budget for conversion of the Department's stockpile of depleted uranium hexafluoride (DUF{sub 6}) to a more stable form over an extended period. The conversion process into a more stable form will produce fluorine compounds (e.g., elemental fluorine or hydrofluoric acid) that need to be handled safely. This document compiles the requirements necessary to handle these materials within health and safety standards, which may apply in order to ensure protection of the environment and the safety and health of workers and the public. Fluorine is a pale-yellow gas with a pungent, irritating odor. It is the most reactive nonmetal and will react vigorously with most oxidizable substances at room temperature, frequently with ignition. Fluorine is a severe irritant of the eyes, mucous membranes, skin, and lungs. In humans, the inhalation of high concentrations causes laryngeal spasm and broncospasms, followed by the delayed onset of pulmonary edema. At sublethal levels, severe local irritation and laryngeal spasm will preclude voluntary exposure to high concentrations, unless the individual is trapped or incapacitated. A blast of fluorine gas on the shaved skin of a rabbit causes a second degree burn. Lower concentrations cause severe burns of insidious onset, resulting in ulceration, similar to the effects produced by hydrogen fluoride. Hydrofluoric acid is a colorless, fuming liquid or gas with a pungent odor. It is soluble in water with release of heat. Ingestion of an estimated 1.5 grams produced sudden death without gross pathological damage. Repeated ingestion of small amounts resulted in moderately advanced hardening of the bones. Contact of skin with anhydrous liquid produces severe burns. Inhalation of AHA or aqueous hydrofluoric acid mist or vapors can cause severe respiratory tract irritation that may be fatal. Based on the extreme chemical

Plants and fluorine

Energy Technology Data Exchange (ETDEWEB)

Garber, K

1962-01-01

A report is given about the contents of fluorine in soil and different plants. It is stated that spinach and several spice herbages are rich in fluorine (0.98 - 21.8 ppm) while in other plants are not more than 5 ppm maximum. An exception is found in Thea sinensis with 178 ppm and more. Tea is, therefore, a source of fluorine for contamination of the human body. An increase of the fluorine contents of plants by manuring with F-salts or mineral manure is possible but of long duration. Damage to plants by uptake of fluorine from soil as well as in a gaseous condition from the atmosphere are described. The rate of damage is related to the type of soil in which the plant is grown.

Fluorinated alkyne-derived monolayers on oxide-free silicon nanowires via one-step hydrosilylation

Energy Technology Data Exchange (ETDEWEB)

Nguyen Minh, Quyen [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands); Nanosens, IJsselkade 7, 7201 HB Zutphen (Netherlands); Pujari, Sidharam P. [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands); Wang, Bin [The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion – Israel Institute of Technology, Haifa 3200003 (Israel); Wang, Zhanhua [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands); Haick, Hossam [The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion – Israel Institute of Technology, Haifa 3200003 (Israel); Zuilhof, Han [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands); Rijn, Cees J.M. van, E-mail: cees.vanrijn@wur.nl [Laboratory of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen (Netherlands)

2016-11-30

Highlights: • Oxide-free H-terminated silicon nanowires undergo efficient surface modification by reaction with fluorinated 1-alkynes (HC≡C−(CH{sub 2}){sub 6}C{sub 8}H{sub 17−x}F{sub x}; x = 0–17). • These surface-modified Si NWs are chemically stable under range of conditions (including acid, base). • The surface coating yields efficient electrical passivation as demonstrated by a near-zero electrochemical activity of the surface. - Abstract: Passivation of oxide-free silicon nanowires (Si NWs) by the formation of high-quality fluorinated 1-hexadecyne-derived monolayers with varying fluorine content has been investigated. Alkyl chain monolayers (C{sub 16}H{sub 30−x}F{sub x}) with a varying number of fluorine substituents (x = 0, 1, 3, 9, 17) were attached onto hydrogen-terminated silicon (Si−H) surfaces with an effective one-step hydrosilylation. This surface chemistry gives well-defined monolayers on nanowires that have a cylindrical core–shell structure, as characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and static contact angle (SCA) analysis. The monolayers were stable under acidic and basic conditions, as well as under extreme conditions (such as UV exposure), and provide excellent surface passivation, which opens up applications in the fields of field effect transistors, optoelectronics and especially for disease diagnosis.

Fluorine and sulfur simultaneously co-doped suspended graphene

Science.gov (United States)

Struzzi, C.; Sezen, H.; Amati, M.; Gregoratti, L.; Reckinger, N.; Colomer, J.-F.; Snyders, R.; Bittencourt, C.; Scardamaglia, M.

2017-11-01

Suspended graphene flakes are exposed simultaneously to fluorine and sulfur ions produced by the μ-wave plasma discharge of the SF6 precursor gas. The microscopic and spectroscopic analyses, performed by Raman spectroscopy, scanning electron microscopy and photoelectron spectromicroscopy, show the homogeneity in functionalization yield over the graphene flakes with F and S atoms covalently bonded to the carbon lattice. This promising surface shows potential for several applications ranging from biomolecule immobilization to lithium battery and hydrogen storage devices. The present co-doping process is an optimal strategy to engineer the graphene surface with a concurrent hydrophobic character, thanks to the fluorine atoms, and a high affinity with metal nanoparticles due to the presence of sulfur atoms.

Fluorine content of Fukien teas

Energy Technology Data Exchange (ETDEWEB)

Wang, T H; Lin, C S; Wu, C; Liao, C E; Lin, H Y

1949-01-01

A study was made on the fluorine contents of Fukien teas and analytical results indicated the amount ranged from 5.7 to 35.5 mg. per 100 grams of dry tea. The high content of fluorine was found not to be due to contamination nor to the high fluorine content of the soil in which the tea plant was cultivated. Differences in the methods of manufacture had no effect on the fluorine content of the final products. Different varieties of tea plants have different powers to absorb fluorine from the soil. Of the two varieties of tea plants studied, Shui-Sen leaves possessed the lower fluorine content. Age of the tea leaves exerted an important influence on the fluorine content, the older leaves containing considerably more fluorine than the younger. The amount of fluorine that may be extracted in a two per cent infusion varies from 29.1 per cent for fresh leaves to 50.5 per cent for black tea. The process of roasting and rolling rendered the fluorine more soluble, hence the amount extracted increased in green tea. Fermentation further increased the extractability of the fluorine; thus the amount extracted was the highest in black tea, which was fermented, less in the semi-fermented oolong tea, and least in the unfermented green tea. The extractability of fluorine was also increased with age of the leaves.

Compilation of Requirements for Safe Handling of Fluorine and Fluorine-Containing Products of Uranium Hexafluoride Conversion

International Nuclear Information System (INIS)

Ferrada, J.J.; Hightower, J.R.; Begovich, J.M.

2000-01-01

Public Law (PL) 105--204 requires the U.S. Department of Energy to develop a plan for inclusion in the fiscal year 2000 budget for conversion of the Department's stockpile of depleted uranium hexafluoride (DUF6) to a more stable form over an extended period. The conversion process into a more stable form will produce fluorine compounds (e.g., elemental fluorine or hydrofluoric acid) that need to be handled safely. This document compiles the requirements necessary to handle these materials within health and safety standards, which may apply in order to ensure protection of the environment and the safety and health of workers and the public

Fluorination of uranium compounds by gaseous bromine trifluoride and a bromine-fluorine mixture

International Nuclear Information System (INIS)

Sakurai, Tsutomu

1976-03-01

This report summarizes the studies of fluorination of uranium compounds by gaseous BrF 3 and a Br 2 -F 2 mixture, which were carried out in Fluorine Chemistry Laboratory of JAERI in connection with the reprocessing method of nuclear fuels. Although thermodynamically more stable than F 2 , BrF 3 has higher reactivity at relatively low temperatures: fluorination of uranium compounds can be carried out at 100 0 -- 200 0 C by using gaseous BrF 3 . This fluorination temperature is lower than those of F 2 , BrF 5 , ClF and SF 4 , and close to that of ClF 3 . The usage of BrF 3 has however the drawbacks that it requires additional devices to heat the corrosive liquid and to remove Br 2 produced as a byproduct. In order to eliminate the difficulties indicated, a new method of fluorination was developed - the use of a Br 2 -F 2 mixture. Addition of small amounts of Br 2 to the fluorine flow (about 6% in relation to the fluorine concentration) gives marked effects on the rate of fluorination. (auth.)

Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

Science.gov (United States)

Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

2015-04-01

To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials ["MS coats F" (MSF)] and fluoride-free sealing materials ("hybrid coats 2" [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8-4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

The rare fluorinated natural products and biotechnological prospects for fluorine enzymology.

Science.gov (United States)

Chan, K K Jason; O'Hagan, David

2012-01-01

Nature has hardly evolved a biochemistry of fluorine although there is a low-level occurrence of fluoroacetate found in selected tropical and subtropical plants. This compound, which is generally produced in low concentrations, has been identified in the plants due to its high toxicity, although to date the biosynthesis of fluoroacetate in plants remains unknown. After that, fluorinated entities in nature are extremely rare, and despite increasingly sophisticated screening and analytical methods applied to natural product extraction, it has been 25 years since the last bona fide fluorinated natural product was identified from an organism. This was the reported isolation of the antibiotic 4-fluorothreonine and the toxin fluoroacetate in 1986 from Streptomyces cattleya. This bacterium has proven amenable to biochemical investigation, the fluorination enzyme (fluorinase) has been isolated and characterized, and the biosynthetic pathway to these bacterial metabolites has been elucidated. Also the fluorinase gene has been cloned into a host bacterium (Salinispora tropica), and this has enabled the de novo production of a bioactive fluorinated metabolite from fluoride ion, by genetic engineering. Biotechnological manipulation of the fluorinase offers the prospects for the assembly of novel fluorinated metabolites by fermentation technology. This is particularly attractive, given the backdrop that about 15-20% of pharmaceuticals licensed each year (new chemical entities) contain a fluorine atom. Copyright © 2012 Elsevier Inc. All rights reserved.

Fluorine-doped tin oxide surfaces modified by self-assembled alkanethiols for thin-film devices

Energy Technology Data Exchange (ETDEWEB)

Alves, A.C.T.; Gomes, D.J.C.; Silva, J.R.; Silva, G.B., E-mail: george@cpd.ufmt.br

2013-08-15

In this work, we have investigated self-assembled monolayers (SAMs) from alkanethiols on fluorine-doped tin oxide (FTO) surfaces, which were used as an anode for thin-film devices prepared from the conductive copolymer so-called sulfonated poly(thiophene-3-[2-(2-methoxyethoxy) ethoxy]-2,5-diyl) (S-P3MEET). The assembled monolayers were characterized by using wetting contact angle, atomic force microscopy, and electrical measurements. The results indicated that dodecanethiol molecules, CH{sub 3}(CH{sub 2}){sub 11}SH, were well assembled on the FTO surfaces. In addition, it was found similar values of wetting contact angle for dodecanethiol assembled on both FTO and Au surfaces. Concerning the thin-film device, current–voltage analysis revealed a hysteresis. This behavior was associated to a charge-trapping effect and also to structural changes of the SAMs. Finally, charge injection capability of tin oxide electrodes can be improved by using SAMs and then this approach can plays an important role in molecular-scale electronic devices.

Characterization of fluorinated silica thin films with ultra-low refractive index deposited at low temperature

Energy Technology Data Exchange (ETDEWEB)

Abbasi-Firouzjah, Marzieh [Semnan Science and Technology Park, 3614933578, Shahrood (Iran, Islamic Republic of); Shokri, Babak, E-mail: b-shokri@sbu.ac.ir [Laser & Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of)

2015-02-27

Structural and optical properties of low refractive index fluorinated silica (SiO{sub x}C{sub y}F{sub z}) films were investigated. The films were deposited on p-type silicon and polycarbonate substrates by radio frequency plasma enhanced chemical vapor deposition method at low temperatures. A mixture of tetraethoxysilane vapor, oxygen, and CF{sub 4} was used for deposition of the films. The influence of oxygen flow rate on the elemental compositions, chemical bonding states and surface roughness of the films was studied using energy dispersive X-ray analyzer, Fourier transform infrared spectroscopy in reflectance mode and atomic force microscopy, respectively. Effects of chemical bonds of the film matrix on optical properties and chemical stability were discussed. Energy dispersive spectroscopy showed high fluorine content in the SiO{sub x}C{sub y}F{sub z} film matrix which is in the range of 7.6–11.3%. It was concluded that in fluorine content lower than a certain limit, chemical stability of the film enhances, while higher contents of fluorine heighten moisture absorption followed by increasing refractive index. All of the deposited films were highly transparent. Finally, it was found that the refractive index of the SiO{sub x}C{sub y}F{sub z} film was continuously decreased with the increase of the O{sub 2} flow rate down to the minimum value of 1.16 ± 0.01 (at 632.8 nm) having the most ordered and nano-void structure and the least organic impurities. This sample also had the most chemical stability against moisture absorption. - Highlights: • Low deposition temperature and organic precursor led to higher film fluorination. • High fluorine and nanovoid structure led to drastic decrease in the refractive index. • Silica based thin film with ultralow refractive index of 1.16 was produced. • The produced ultralow-n film is highly stable against moisture absorption.

Mechanical and Structural Properties of Fluorine-Ion-Implanted Boron Suboxide

Directory of Open Access Journals (Sweden)

Ronald Machaka

2012-01-01

degradation of near-surface mechanical properties with increasing fluorine fluence. Implications of these observations in the creation of amorphous near-surface layers by high-dose ion implantation are discussed in this paper.

Surface and grain boundary modifications of YBa2Cu3O7-δ ceramics by plasma-enhanced fluorination

International Nuclear Information System (INIS)

Magro, C.; Heintz, J.M.; Etourneau, J.; Tressaud, A.; Cardinaud, C.; Turban, G.; Hudakova, N.

1994-01-01

The radiofrequency plasma technique involving mixtures of CF 4 + O 2 gases has been applied to the treatment of high T c superconducting oxides (YBa 2 Cu 3 O 7-δ ). The investigation of the various experimental parameters of the process has shown that the improvement of the critical current density J c mainly depends on the inlet precursor composition CF 4 + τ % O 2 , on the total pressure, and on the reaction time. The presence of fluorine in the bulk of the ceramics has been observed from electron microprobe analysis, together with an increase of the open-quotes Cu 3+ close quotes content. The plasma enhanced fluorination (PEF) treatment improves the superconducting properties of the materials: both values of the resistivity in the normal state and of the superconducting transition width are reduced and the critical transition temperature is improved of about 1 K. Mechanisms of interaction between the reactive species of the plasma and YBa 2 Cu 3 O 7-δ ceramics have been proposed through detailed angle resolved X-ray photoelectron spectroscopic analyses. At the surface of the outer grains, the plasma treatment removes (OH) - and (CO 3 ) 2- species contained in the degradation layer and gives rise to a fluoride-rich layer. In the bulk of the material the occurrence of metal-fluorine bonds in the superconducting phase has to be assumed. Moreover, interactions between atomic fluorine and grain boundaries result in an improvement of intergranular magnetic behavior, according to a.c. susceptibility measurements. An increase of the oxidation state of copper has also been detected, confirming the oxidizing effect of the plasma treatment

Frequency effects and properties of plasma deposited fluorinated silicon nitride

International Nuclear Information System (INIS)

Chang, C.; Flamm, D.L.; Ibbotson, D.E.; Mucha, J.A.

1988-01-01

The properties of low-hydrogen, fluorinated plasma-enhanced chemical vapor deposition (PECVD) silicon nitride films grown using NF 3 /SiH 4 /N 2 feed mixtures in 200 kHz and 14 MHz discharges were compared. High-energy ion bombardment at 200 kHz is expected to enhance surface diffusion and chemical reconstruction. Compared to fluorinated silicon nitride deposited at 14 MHz under otherwise comparable conditions, the 200 kHz films had a lower Si--H bond concentration (approx. 21 cm -3 ), lower total hydrogen content (5--8 x 10 21 cm -3 ), better resistance to oxidation, lower compressive stress (-0.7 to -1.5 Gdyne/cm), and higher density (3.1 g/cm 3 ). The dielectric constant of better low-frequency Class I films was constant to 500 MHz, while that of high-frequency films fell up to 15% between 100 Hz and 10 MHz. The absorption edges of low-frequency PECVD fluorinated silicon nitride films were between 5.0 and 6.1 eV, which compare with 4.4 to 5.6 eV for the high-excitation frequency fluorinated material and 3 to 4 eV for conventional PECVD nitride. However high-frequency films may have fewer trap centers and a lower dielectric constant. 14 MHz p-SiN:F films grown with NH 3 as an auxiliary nitrogen source showed absorption edges similar to low-frequency material grown from NF 3 /SiH 4 /N 2 , but they have substantially more N--H bonding. The dielectric constant and absorption edge of these films were comparable to those of low-frequency p-SiN:F from NF 3 /SiH 4 /N 2

Fluorine in medicinal chemistry.

Science.gov (United States)

Swallow, Steven

2015-01-01

Since its first use in the steroid field in the late 1950s, the use of fluorine in medicinal chemistry has become commonplace, with the small electronegative fluorine atom being a key part of the medicinal chemist's repertoire of substitutions used to modulate all aspects of molecular properties including potency, physical chemistry and pharmacokinetics. This review will highlight the special nature of fluorine, drawing from a survey of marketed fluorinated pharmaceuticals and the medicinal chemistry literature, to illustrate key concepts exploited by medicinal chemists in their attempts to optimize drug molecules. Some of the potential pitfalls in the use of fluorine will also be highlighted. © 2015 Elsevier B.V. All rights reserved.

Bacterial degradation of fluorinated compounds

NARCIS (Netherlands)

Ferreira, Maria Isabel Martins

2007-01-01

Fluorine was produced for the first time by Henri Moissan in 1886, for which he received the Nobel Prize in chemistry in 1906. The unique properties of fluorine have led to the development of fluorine chemistry and numerous synthetic fluorinated compounds have been prepared and tested for different

Comparison of the Fouling Release Properties of Hydrophobic Fluorinated and Hydrophilic PEGylated Block Copolymer Surfaces

International Nuclear Information System (INIS)

Krishnan, S.; Wang, N.; Ober, C.; Finlay, J.; Callow, M.; Callow, J.; Hexemer, A.; Sohn, K.; Kramer, E.; Fischer, D.

2006-01-01

To understand the role of surface wettability in adhesion of cells, the attachment of two different marine algae was studied on hydrophobic and hydrophilic polymer surfaces. Adhesion of cells of the diatom Navicula and sporelings (young plants) of the green macroalga Ulva to an underwater surface is mainly by interactions between the surface and the adhesive exopolymers, which the cells secrete upon settlement and during subsequent colonization and growth. Two types of block copolymers, one with poly(ethylene glycol) side-chains and the other with liquid crystalline, fluorinated side-chains, were used to prepare the hydrophilic and hydrophobic surfaces, respectively. The formation of a liquid crystalline smectic phase in the latter inhibited molecular reorganization at the surface, which is generally an issue when a highly hydrophobic surface is in contact with water. The adhesion strength was assessed by the fraction of settled cells (Navicula) or biomass (Ulva) that detached from the surface in a water flow channel with a wall shear stress of 53 Pa. The two species exhibited opposite adhesion behavior on the same sets of surfaces. While Navicula cells released more easily from hydrophilic surfaces, Ulva sporelings showed higher removal from hydrophobic surfaces. This highlights the importance of differences in cell-surface interactions in determining the strength of adhesion of cells to substrates

Self-lubricating fluorine shaft seal material

Science.gov (United States)

Munk, W. R.

1970-01-01

Lubricating film is produced by a reaction of fluorine with a composite of aluminum oxide and nickel powder. The rate of nickel fluoride generation is proportional to the rate at which the fluoride is rubbed off the surface, allowing the seal to operate with the lowest possible heating.

Application of fluorinated nanofluid for production enhancement of a carbonate gas-condensate reservoir through wettability alteration

Science.gov (United States)

Sakhaei, Zahra; Azin, Reza; Naghizadeh, Arefeh; Osfouri, Shahriar; Saboori, Rahmatollah; Vahdani, Hosein

2018-03-01

Condensate blockage phenomenon in near-wellbore region decreases gas production rate remarkably. Wettability alteration using fluorinated chemicals is an efficacious way to vanquish this problem. In this study, new synthesized fluorinated silica nanoparticles with an optimized condition and mean diameter of 50 nm is employed to modify carbonate rock surface wettability. Rock characterization tests consisting Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive x-ray Spectroscopy (EDX) were utilized to assess the nanofluid adsorption on rock surface after treatment. Contact angle, spontaneous imbibition and core flooding experiments were performed to investigate the effect of synthesized nanofluid adsorption on wettability of rock surface and liquid mobility. Results of contact angle experiments revealed that wettability of rock could alter from strongly oil-wetting to the intermediate gas-wetting even at elevated temperature. Imbibition rates of oil and brine were diminished noticeably after treatment. 60% and 30% enhancement in pressure drop of condensate and brine floods after wettability alteration with modified nanofluid were observed which confirm successful field applicability of this chemical.

In-vivo analysis of fluorine and other elements in human tooth enamel

International Nuclear Information System (INIS)

Baijot-Stroobants, J.; Vreven, J.

1979-01-01

The technique used to study fluorination of human tooth enamel is based on prompt activation by charged particles and detection of the 110- and 197-keV gamma rays emitted in the (p,p'γ) reaction on fluorine. The proton beam is provided by the Van de Graaff accelerator at the University of Namur and is used at atmospheric pressure. The technique can be used for non-destructive determination of fluorine concentrations of the same area of enamel both before and after topical application of fluorinated compounds (commercial solutions and gels) and thus for determination of fluorine fixation in the surface layer of the enamel. A very high degree of enrichment is obtained 30 min after the application of a solution of amine fluoride (AmF; 4400 ppm) and of two fluorophosphate acid (APF) gels (1774 and 3277 ppm). Monofluorophosphate (MFP) and amine fluoride (AmF) gels, however, produce insignificant degrees of enrichment (105 and 228 ppm). Measurement of fluorine retention during the hours after fluorination shows a small loss of fluorine 6 h after application of the AmF solution and the APF gels, whereas with MFP and AmF gels the degree of enrichment is nil 5 h after treatment. Determinations of sodium and of phosphorus have also been carried out with the same technique after brushing with a fluorinated tooth-paste or after topical application of a fluorinated gel. (author)

Study of copper fluorination

International Nuclear Information System (INIS)

Gillardeau, J.

1967-02-01

This report deals with the action of fluorine on copper. Comprehensive descriptions are given of the particular technological methods and of the preparation of the reactants. This fluorination reaction has been studied at medium and low fluorine pressures. A nucleation and growth phenomenon is described. The influence of a pollution of the gas phase on the fluorination process is described. The solid-state reaction between cupric fluoride and cooper has also been studied. A special study has been made of the growth of copper deposits by thermal decomposition of gaseous fluorides. (author) [fr

Compendium of fluorine data

International Nuclear Information System (INIS)

Detamore, J.A.

1983-01-01

Research was conducted to locate information about fluorine. This information includes chemical and physical properties of fluorine, physiological effects produced by the material, first-aid, personnel and facility protection, and materials of construction required when handling fluorine in piping and process vessels. The results of this research have been compiled in this report

Revisited study of fluorine implantation impact on negative bias temperature instability for input/output device of automotive micro controller unit

Science.gov (United States)

Yoshida, Tetsuya; Maekawa, Keiichi; Tsuda, Shibun; Shimizu, Tatsuo; Ogasawara, Makoto; Aono, Hideki; Yamaguchi, Yasuo

2018-04-01

We investigate the effect of fluorine implanted in the polycrystalline silicon (poly-Si) gate and source/drain (S/D) region on negative bias temperature instability (NBTI) improvement. It is found that there is a trade-off implantation energy dependence of NBTI between fluorine in the poly-Si gate and that in the S/D region. Fluorine implanted in the poly-Si gate contributes to NBTI improvement under low energy implantation. On the other hand, NBTI is improved by fluorine implanted in the S/D region under high energy. We propose that the two-step implantation process with high and low energy is the optimum condition for NBTI improvement.

Fluorine-18-labelled molecules: synthesis and application in medical imaging

International Nuclear Information System (INIS)

Dolle, F.; Perrio, C.; Barre, L.; Lasne, M.C.; Le Bars, D.

2006-01-01

Positron emission tomography (PET) is one of the more powerful available techniques for medical imaging. It relies on the use of molecules labelled with a positron emitter (β + ). Among those emitters, fluorine-18, available from a cyclotron, is a radionuclide of choice because of its relatively long-half-life (109.8 min) and the relatively low energy of the emitted-positron. The electrophilic form of fluorine-18 ([ 18 F]F 2 or reagents derived from [ 18 F]F 2 ) is mainly used for hydrogen or metal substitutions on aromatic or vinylic carbons. The presence of the stable isotope (fluorine-19) in the radiotracers limits their use in medical imaging. The nucleophilic form of fluorine-18 (alkaline mono-fluoride, K[ 18 F]F, the most used), obtained from irradiation of enriched water, is widely used in aliphatic and (hetero)aromatic substitutions for the synthesis of radiotracers with high specific radioactivity. Some examples of radio-fluorinated tracers used in PET are presented, as well as some of their in vivo applications in human. (authors)

WO3 and W Thermal Atomic Layer Etching Using "Conversion-Fluorination" and "Oxidation-Conversion-Fluorination" Mechanisms.

Science.gov (United States)

Johnson, Nicholas R; George, Steven M

2017-10-04

The thermal atomic layer etching (ALE) of WO 3 and W was demonstrated with new "conversion-fluorination" and "oxidation-conversion-fluorination" etching mechanisms. Both of these mechanisms are based on sequential, self-limiting reactions. WO 3 ALE was achieved by a "conversion-fluorination" mechanism using an AB exposure sequence with boron trichloride (BCl 3 ) and hydrogen fluoride (HF). BCl 3 converts the WO 3 surface to a B 2 O 3 layer while forming volatile WO x Cl y products. Subsequently, HF spontaneously etches the B 2 O 3 layer producing volatile BF 3 and H 2 O products. In situ spectroscopic ellipsometry (SE) studies determined that the BCl 3 and HF reactions were self-limiting versus exposure. The WO 3 ALE etch rates increased with temperature from 0.55 Å/cycle at 128 °C to 4.19 Å/cycle at 207 °C. W served as an etch stop because BCl 3 and HF could not etch the underlying W film. W ALE was performed using a three-step "oxidation-conversion-fluorination" mechanism. In this ABC exposure sequence, the W surface is first oxidized to a WO 3 layer using O 2 /O 3 . Subsequently, the WO 3 layer is etched with BCl 3 and HF. SE could simultaneously monitor the W and WO 3 thicknesses and conversion of W to WO 3 . SE measurements showed that the W film thickness decreased linearly with number of ABC reaction cycles. W ALE was shown to be self-limiting with respect to each reaction in the ABC process. The etch rate for W ALE was ∼2.5 Å/cycle at 207 °C. An oxide thickness of ∼20 Å remained after W ALE, but could be removed by sequential BCl 3 and HF exposures without affecting the W layer. These new etching mechanisms will enable the thermal ALE of a variety of additional metal materials including those that have volatile metal fluorides.

Nuclear energy - Determination of chlorine and fluorine in uranium dioxide powder and sintered pellets

International Nuclear Information System (INIS)

2008-01-01

This International Standard describes a method for determining the chlorine and fluorine concentrations in uranium dioxide and in sintered fuel pellets by pyrohydrolysis of samples, followed either by liquid ion-exchange chromatography or by selective electrode measurement of chlorine and fluorine ions. Many ion-exchange chromatography systems and ion-selective electrode measurement systems are available

Fluorination methods in drug discovery

OpenAIRE

Yerien, Damián Emilio; Bonesi, Sergio Mauricio; Postigo, Jose Alberto

2017-01-01

Fluorination reactions of medicinal and biologically-active compounds will be discussed. Late stage fluorination strategies of medicinal targets have recently attracted considerable attention on account of the influence that the fluorine atom can impart to targets of medicinal importance, such as a modulation of lipophilicity, electronegativity, basicity and bioavailability, this latter as a consequence of membrane permeability. Therefore, the recourse to late-stage fluorine substitution on c...

Diffusion modelling of low-energy ion-implanted BF{sub 2} in crystalline silicon: Study of fluorine vacancy effect on boron diffusion

Energy Technology Data Exchange (ETDEWEB)

Marcon, J. [Laboratoire Electronique Microtechnologie et Instrumentation (LEMI), University of Rouen, 76821 Mont Saint Aignan (France)], E-mail: Jerome.Marcon@univ-rouen.fr; Merabet, A. [Laboratoire de Physique et Mecanique des Materiaux Metalliques, Departement d' O.M.P., Faculte des Sciences de l' Ingenieur, Universite de Setif, 19000 Setif (Algeria)

2008-12-05

We have investigated and modelled the diffusion of boron implanted into crystalline silicon in the form of boron difluoride BF{sub 2}{sup +}. We have used published data for BF{sub 2}{sup +} implanted with an energy of 2.2 keV in crystalline silicon. Fluorine effects are considered by using vacancy-fluorine pairs which are responsible for the suppression of boron diffusion in crystalline silicon. Following Uematsu's works, the simulations satisfactory reproduce the SIMS experimental profiles in the 800-1000 deg. C temperature range. The boron diffusion model in silicon of Uematsu has been improved taking into account the last experimental data.

Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

Energy Technology Data Exchange (ETDEWEB)

Yasuhiro, Matsuda, E-mail: matsuda@den.hokudai.ac.jp [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Katsushi, Okuyama [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Hiroko, Yamamoto [Graduate School of Dentistry, Osaka University (Japan); Hisanori, Komatsu [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Masashi, Koka; Takahiro, Sato [Takasaki Advanced Radiation Research Institute, JAEA (Japan); Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan)

2015-04-01

To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

International Nuclear Information System (INIS)

Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

2015-01-01

To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries

Fluorine content in the soft tissues, blood and milk of ruminants outside and inside fluorine emission areas

Energy Technology Data Exchange (ETDEWEB)

Oelschlaeger, W; Feyler, L; Schwarz, E

1972-01-01

Data on the fluorine content of soft tissues, blood and milk inside and outside fluorine emission areas vary widely, probably because of analytical difficulties. Possible errors and their elimination are discussed. A large number of analyses was carried out to determine the fluorine content of heart, liver, lung, kidney, adrenal, muscle, spleen, pancreas, lymph nodes, thyroid, thymus, pituitary and cerebrum and cerebellum of cows and calves, as well as 388 milk samples and 232 blood samples. In calves born from cows kept for 3 1/2 years near a factory producing hydrofluoric acid, there was a clear relationship between the fluorine content during the suckling and drinking period, and also in a still-born calf, with the fluorine uptake of the dam during the months of pregnancy. In contrast to cattle, calves showed significantly higher fluorine levels in the adrenals compared with the kidneys. The soft tissues of cattle outside the fluorine emission areas contained more fluorine than in calves within the emission areas. Fluorine accumulation in liver, lung, kidney, cerebrum and cerebellum, thyroid and pituitary was markedly raised in animals with high fluorine uptake, whereas there was no significant change in the levels in the heart, musculature and spleen. So far as human health is concerned, the raised fluorine level in milk was significantly below the maximum level permitted in fluoridated drinking water.

Microanalysis of Fluorine Contamination and its Depth Distribution in Zircaloy by the Use of a Charged Particle Nuclear Reaction

Energy Technology Data Exchange (ETDEWEB)

Moeller, E; Starfelt, N

1966-07-15

Fluorine contamination on and below the surface of zircaloy has been studied by means of proton irradiation using a Van de Graaff accelerator and the detection of prompt gamma radiation from the {sup 19}F (p, {alpha}{gamma}) {sup 16}O reaction. Formulae for deriving depth distributions of impurities from the measured counting rates have been derived. The influence of energy straggling on the depth resolution has been studied. Both the total amount and the depth distribution have been measured in samples, which have undergone different treatments. Because of the high yield from the reaction used, a quantity of fluorine less than 0. 01 {mu}g/cm{sup 2} can be detected by this method.

Diels-Alder reactions onto fluorinated and hydrogenated graphene

Science.gov (United States)

Denis, Pablo A.

2017-09-01

We studied Diels-Alder (DA) reactions onto functionalized graphene. When fluorine, hydrogen or oxygen functional groups are present on one side of the sheet, the DA cycloadditions become significantly more exergonic when performed on the opposite side. Hydrogen is more effective than fluorine and oxygen to promote these cycloadditions. In contrast with the results obtained for perfect graphene, the functionalization with H, F or O turns the DA reactions exergonic, with ΔG°298 = -127.2 kcal/mol. The reaction barriers are expected to be considerably lowered with respect to perfect graphene because the functional groups significantly reduce the distortion energy.

Fabrication and characterization of stable superhydrophobic fluorinated-polyacrylate/silica hybrid coating

Science.gov (United States)

Li, Kunquan; Zeng, Xingrong; Li, Hongqiang; Lai, Xuejun

2014-04-01

The core-shell fluorinated-polyacrylate (PFA) emulsion was synthesized through emulsion polymerization method and the superhydrophobic PFA/SiO2 hybrid coating was successfully fabricated on the slide glass by spraying the mixture of PFA emulsion and hydrophobic SiO2 particles using ethanol as cosolvent. The PFA emulsion was characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), water contact angle (WCA), transmission electron microscopy (TEM), and the effects of SiO2 content on the wetting behavior and surface morphology of PFA/SiO2 hybrid coating were investigated. To evaluate the stability of the hybrid coating, the acid and base resistance, weatherability and thermal stability were also studied. Results showed that the obtained PFA latex exhibited a core-shell structure with a particle size of 134.1 nm and a narrow polydispersity of 0.03. With the increase of dodecafluoroheptyl methacrylate (DFMA) content in the latex shell from 0 wt% to 31.8 wt%, the WCA of the PFA film enlarged from 85° to 104°, indicating that the introduction of fluorinated monomer was effective in reducing the surface energy. By adding different amount of SiO2 particles, the surface morphology and wetting behavior of the PFA/SiO2 hybrid coatings could be controlled. When the mass ratio of SiO2 to PFA emulsion was 0.2, the surface roughness (Rq) increased to 173.6 nm and the wetting behavior of the surface became superhydrophobic with a WCA of 153°, resulted from the corporation of low surface energy and the binary nano/microstructure on the surface. The as-prepared PFA/SiO2 hybrid coating showed good acid and base corrosion resistance, and it could keep superhydrophobicity after being heated at 250 °C for 2 h or exposed to ambient atmosphere for more than 3 months. Additionally, the superhydrophobic PFA/SiO2 hybrid coating could be applied to various substrates through spraying. This was a green and eco-friendly method in fabricating stable

Analysis of fluorine by nuclear reactions and applications to human dental enamel

International Nuclear Information System (INIS)

Stroobants, J.; Bodart, F.; Deconninck, G.; Demortier, G.; Nicolas, G.

Nuclear reactions induced on Fluorine by low energy protons are investigated, thick target excitation yield curves and tables for 19 F(p,p'γ) 19 F and 19 F(p,αγ) 16 O reactions are given between 0.3 and 2.5 MeV. Interferences from other nuclear reactions, detection limits and sensitivity for Fluorine detection are investigated. After a wide investigation of the repartition of Fluorine in tooth enamel it is concluded that there is an equilibrium of the concentrations between tooth and saliva which is rapidly restored after the perturbation introduced by the external treatments. (author)

Autoionizing states in highly ionized oxygen, fluorine and silicon

International Nuclear Information System (INIS)

Forester, J.P.; Peterson, R.S.; Griffin, P.M.; Pegg, D.J.; Haselton, H.H.; Liao, K.H.; Sellin, I.A.; Mowat, J.R.; Thoe, R.S.

1975-01-01

Autoionizing states in high Z 3-electron ions associated with core excited configurations of the type 1s2snl and 1s2pnl are reported. The electron decay-in-flight spectra of lithium-like oxygen, fluorine, and silicon ions are presented. Initial beam energies of 6.75-MeV oxygen and fluorine ions and 22.5-MeV silicon ions were used. Stripping and excitation were done by passing the beams through a thin carbon foil. The experimental technique is described. 4 figs, 1 table, 7 refs

The Curious Case of Fluorination of Conjugated Polymers for Solar Cells.

Science.gov (United States)

Zhang, Qianqian; Kelly, Mary Allison; Bauer, Nicole; You, Wei

2017-09-19

Organic solar cells (OSCs) have been a rising star in the field of renewable energy since the introduction of the bulk heterojunction (BHJ) in 1992. Recent advances have pushed the efficiencies of OSCs to over 13%, an impressive accomplishment via collaborative efforts in rational materials design and synthesis, careful device engineering, and fundamental understanding of device physics. Throughout these endeavors, several design principles for the conjugated donor polymers used in such solar cells have emerged, including optimizing the conjugated backbone with judicious selection of building blocks, side-chain engineering, and substituents. Among all of the substituents, fluorine is probably the most popular one; improved device characteristics with fluorination have frequently been reported for a wide range of conjugated polymers, in particular, donor-acceptor (D-A)-type polymers. Herein we examine the effect of fluorination on the device performance of solar cells as a function of the position of fluorination (on the acceptor unit or on the donor unit), aiming to outline a clear understanding of the benefits of this curious substituent. As fluorination of the acceptor unit is the most adopted strategy for D-A polymers, we first discuss the effect of fluorination of the acceptor units, highlighting the five most widely utilized acceptor units. While improved device efficiency has been widely observed with fluorinated acceptor units, the underlying reasons vary from case to case and highly depend on the chemical structure of the polymer. Second, the effect of fluorination of the donor unit is addressed. Here we focus on four donor units that have been most studied with fluorination. While device-performance-enhancing effects by fluorination of the donor units have also been observed, it is less clear that fluorine will always benefit the efficiency of the OSC, as there are several cases where the efficiency drops, in particular with "over-fluorination", i.e., when

Effects of fluorine contamination on spin-on dielectric thickness in semiconductor manufacturing

Science.gov (United States)

Kim, Hyoung-ryeun; Hong, Soonsang; Kim, Samyoung; Oh, Changyeol; Hwang, Sung Min

2018-03-01

In the recent semiconductor industry, as the device shrinks, spin-on dielectric (SOD) has been adopted as a widely used material because of its excellent gap-fill, efficient throughput on mass production. SOD film must be uniformly thin, homogeneous and free of particle defects because it has been perfectly perserved after chemical-mechanical polishing (CMP) and etching process. Spin coating is one of the most common techniques for applying SOD thin films to substrates. In spin coating process, the film thickness and uniformity are strong function of the solution viscosity, the final spin speed and the surface properties. Especially, airborne molecular contaminants (AMCs), such as HF, HCl and NH3, are known to change to surface wetting characteristics. In this work, we study the SOD film thickness as a function of fluorine contamination on the wafer surface. To examine the effects of airborne molecular contamination, the wafers are directly exposed to HF fume followed by SOD coating. It appears that the film thickness decreases by higher contact angle on the wafer surface due to fluorine contamination. The thickness of the SOD film decreased with increasing fluorine contamination on the wafer surface. It means that the wafer surface with more hydrophobic property generates less hydrogen bonding with the functional group of Si-NH in polysilazane(PSZ)-SOD film. Therefore, the wetting properties of silicon wafer surfaces can be degraded by inorganic contamination in SOD coating process.

Study on characteristics of fluorine concentration profiles in fluorosis sheep teeth and bones

International Nuclear Information System (INIS)

Song Shizhan; Shui Yongqing; Wang Lianbin; Yang Huazhong; Zhai Xujiu; Wang Yuwen; Lei Guilin

1990-01-01

The deep-ward fluorine concentration profiles in fluorosis sheep teeth and bones were determined through 19 F(p, αγ) 16 O reaction with proton energy 3.2 MeV. The profiles show a diffusion characteristic, indicating that the fluorine ion diffusion may be one of the important factors that brought forth pathological changes of livestock teeth and bones

Micro-PIGE determination of fluorine distribution in developing hamster tooth germs

International Nuclear Information System (INIS)

Lyaruu, D.M.; Lenglet, W.J.; Woeltgens, J.H.B.; Bronckers, A.L.

1989-01-01

A micro-PIGE (Proton-Induced gamma-ray Emission) technique based on the delayed 5/2+----1/2+ nuclear transition of fluorine (E gamma = 197 keV, t1/2 = 87 ns) emitted after 19 F(p,p', gamma) 19 F reaction was used to detect and study the distribution of fluorine in the developing enamel organ during pre-eruptive stages, i.e., the transitional to early maturation stages of enamel formation in neonatal hamsters administered a single IP dose of sodium fluoride (20 mg NaF/kg body weight). The aforementioned nuclear reaction is unique for fluorine, and therefore detection of gamma-rays emanating from this reaction in a biological specimen implies a positive identification of fluorine at that particular site. Calcium and phosphorus X-rays were also recorded and used as parameters for assessment of the relationship between the degree of mineralization and fluoride incorporation into the enamel organ. The highest fluorine concentration in the enamel organ was recorded in the dentin near the dentin-enamel junction (DEJ). In the enamel, the highest concentration of fluorine was found to be associated with the more mature areas of the enamel near the DEJ, but gradually decreased in the direction of the enamel surface. Fluorine was not detected in the control germs. These results suggest that administration of fluoride in high doses during the pre-eruptive stages of enamel formation leads to incorporation of the ion into the forming dentin and enamel mineral, and that the enamel matrix does not seem to bind fluoride avidly

An accurate potential energy surface for the F + H2 → HF + H reaction by the coupled-cluster method

International Nuclear Information System (INIS)

Chen, Jun; Sun, Zhigang; Zhang, Dong H.

2015-01-01

A three dimensional potential energy surface for the F + H 2 → HF + H reaction has been computed by the spin unrestricted coupled cluster method with singles, doubles, triples, and perturbative quadruples [UCCSDT(2) Q ] using the augmented correlation-consistent polarised valence quadruple zeta basis set for the fluorine atom and the correlation-consistent polarised valence quadruple zeta basis set for the hydrogen atom. All the calculations are based on the restricted open-shell Hartree-Fock orbitals, together with the frozen core approximations, and the UCCSD(T)/complete basis set (CBS) correction term was included. The global potential energy surface was calculated by fitting the sampled ab initio points without any scaling factor for the correlation energy part using a neutral network function method. Extensive dynamics calculations have been carried out on the potential energy surface. The reaction rate constants, integral cross sections, product rotational states distribution, and forward and backward scattering as a function of collision energy of the F + HD → HF + D, F + HD → DF + H, and F + H 2 reaction, were calculated by the time-independent quantum dynamics scattering theory using the new surface. The satisfactory agreement with the reported experimental observations previously demonstrates the accuracy of the new potential energy surface

Broad bandwidth vibration energy harvester based on thermally stable wavy fluorinated ethylene propylene electret films with negative charges

Science.gov (United States)

Zhang, Xiaoqing; Sessler, Gerhard M.; Ma, Xingchen; Xue, Yuan; Wu, Liming

2018-06-01

Wavy fluorinated ethylene propylene (FEP) electret films with negative charges were prepared by a patterning method followed by a corona charging process. The thermal stability of these films was characterized by the surface potential decay with annealing time at elevated temperatures. The results show that thermally stable electret films can be made by corona charging followed by pre-aging treatment. Vibration energy harvesters having a very simple sandwich structure, consisting of a central wavy FEP electret film and two outside metal plates, were designed and their performance, including the resonance frequency, output power, half power bandwidth, and device stability, was investigated. These harvesters show a broad bandwidth as well as high output power. Their performance can be further improved by using a wavy-shaped counter electrode. For an energy harvester with an area of 4 cm2 and a seismic mass of 80 g, the output power referred to 1 g (g is the gravity of the earth), the resonance frequency, and the 3 dB bandwidth are 1.85 mW, 90 Hz, and 24 Hz, respectively. The output power is sufficient to power some electronic devices. Such devices may be embedded in shoe soles, carpets or seat cushions where the flexibility is required and large force is available.

Degree of functionalization and stability of fluorine groups fixed to carbon nanotubes and graphite nanoplates by CF{sub 4} microwave plasma

Energy Technology Data Exchange (ETDEWEB)

Abdelkader-Fernández, V.K.; Morales-Lara, F. [Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain); Melguizo, M.; García-Gallarín, C.; López-Garzón, R.; Godino-Salido, M.L. [Departamento de Química Inorgánica y Orgánica, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071 Jaén (Spain); López-Garzón, F.J., E-mail: flopez@ugr.es [Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain); Domingo-García, M.; Pérez-Mendoza, M.J. [Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, 18071 Granada (Spain)

2015-12-01

Highlights: • The surface area of GNPs and MWCNTs determines the degree of fluorination by plasma. • Fluorine is bound to carbon atoms in up to eight chemical environments. • The stability of the fluorine groups varies in a wide range of temperature. • The electronic properties of MWCNTs are changed as a consequence of fluorination. • The textural characteristics of the materials are not changed after fluorination. - Abstract: The fluorination of graphite nanoplates (GNPs) and multi-wall carbon nanotubes (MWCNTs) by CF{sub 4} cold plasma is reported. The aim is to analyze the influence of the textural characteristics in the degree of fluorination and in the thermal stability of the fluorine groups. We have used thermal programmed desorption which clearly discriminates the nature of the desorbing species and their stability. The degree of fluorination of both materials is similar up to 20 min of treatment and then it decreases in GNPs at longer treatments. Nevertheless, the fluorine content in MWCNTs keeps increasing after 45 min. This different evolution of the fluorination degree with the time is related to the surface areas. The fluorine bonding is produced not only in defects and irregularities but also on the external graphene sheets of both materials, and it results in up to eight different chemical environments having different thermal stabilities from 150 °C up to temperatures higher than 900 °C. The fluorination increases the electronic states near the Fermi level of the nanotubes whereas it does not affect the electronic properties of graphite nanoplates. It is shown that no intercalation compounds are formed and that the textural characteristics of the materials remain unchanged after fluorination.

Effects of backbone conformation and surface texture of polyimide alignment film on the pretilt angle of liquid crystals

International Nuclear Information System (INIS)

Chang, Chi-Jung; Chou, Ray-Lin; Lin, Yu-Chi; Liang, Bau-Jy; Chen, Jyun-Ji

2011-01-01

Polyimides (PIs) with different inclination angle of polymer backbones, together with polar hydroxyl group and/or nonpolar trifluoromethyl group at various sites of the backbone were synthesized and used as liquid crystal alignment layers. The molecular conformation, surface chemistry, surface energy, surface morphology, and pretilt angle of the PI film were investigated. The distributions of fluorinated group and hydroxyl group at different depths of the PI surfaces were analyzed by X-ray photoelectron spectroscopy. Effects of the conformation of the PI molecular backbone on the surface morphology of the rubbed PI layer, the pretilt angle and surface energy of the alignment film were studied. The PI which contains both nonpolar fluorinated groups sticking out of the surface and the polar hydroxyl groups on the surface exhibits high pretilt angle.

Preparation and characterization of silica/fluorinated acrylate copolymers hybrid films and the investigation of their icephobicity

International Nuclear Information System (INIS)

Huang Yanfen; Hu Mingjie; Yi Shengping; Liu Xinghai; Li Houbin; Huang Chi; Luo Yunbai; Li Yan

2012-01-01

Inexpensive hydrophobic and icephobic coatings and films were obtained by a simple method. These coatings were prepared by mixing silica sol and fluorinated acrylate copolymers. There was a phase separation process in the film-forming which can provide the excellent performance. Small amount (about 2 wt.%) of fluorinated (methyl) acrylate was used in all of these coatings. The coatings were eco-friendly by using ethanol as the solvent system. Scanning electron microscopy, atomic force microscope, energy dispersive X-ray fluorescence spectrometer, water contact angle, thermal gravimetric analysis and tests of adhesion and hardness had been performed to characterize the morphological feature, chemical composition, hydrophobicity and icephobicity of the surface, thermal stability and mechanical properties of the coatings. The results showed that the films had good hydrophobicity, high thermal stability and excellent mechanical properties of adhesion strength and pencil hardness. Furthermore, by testing their properties of delaying water droplet from icing, it was found that ice formation was delayed for 90 min compared with the glass surface at − 5.6 °C. The hybrid coatings may be suitable for large-scale and practical application owing to its flexibility and simplicity. - Highlights: ► Coatings were prepared by mixing fluorinated acrylate copolymer and silica. ► Mechanical properties and anti-icing performance of the coatings were examined. ► Water contact angle increased with raising SiO 2 (sol)/monomers weight ratio. ► Ice formation was delayed for 90 min at − 5.6 °C.

Fluorine determination in human healthy and carious teeth using the PIGE technique

International Nuclear Information System (INIS)

Carvalho, M.L.; Karydas, A.G.; Casaca, C.; Zarkadas, Ch.; Paradellis, Th.; Kokkoris, M.; Nsouli, B.; Cunha, A.S.

2001-01-01

The purpose of this study is to determine and compare the fluorine concentration in human teeth from two different populations, living in the Portuguese quite isolated islands of Acores: S. Miguel and Terceira. Both populations have similar dietary habits, similar occupational activities, mostly rural, and the age of both populations is more or less the same, around 40 years. No chronic diseases were registered in any of the donors. The two groups are exposed to different levels of fluorine in drinking water. Terceira island has moderate fluorine concentration levels (1-2 μg g -1 ) while S. Miguel island is known for the high fluorine concentration levels in its water (>3 μg g -1 ), especially in one area known as Furnas. Thirty-three teeth, 17 healthy and 16 carious without restoration (14 incisors and canines, 7 premolars and 12 molars), were collected and analyzed for the determination of fluorine concentration in the dentine region, using the nuclear reaction 19 F(p,αγ) 16 O. The teeth were cross-sectioned along the vertical plane and polished, in order to obtain a smooth and plane surface of about 1 mm thickness. In this work an association between caries prevalence and fluorine content of drinking water is discussed and the variation of fluorine concentration among different types of teeth (canines and incisors, premolars, molars) and physical state (carious and non-carious) is examined

Triple layered core–shell structure with surface fluorinated ZnO-carbon nanotube composites and its electron emission properties

International Nuclear Information System (INIS)

Wang, H.Y.; Chua, Daniel H.C.

2013-01-01

Highlights: ► The effects of CF 4 plasma on ZnO-CNT core–shell structures were studied. ► ZnO was effective in protecting the aligned CNTs core for as long as 30 min of plasma etching. ► SEM showed the surface morphology was nearly similar between pristine, 2 min and 30 min plasma etched specimens. ► F was observed to displace O in ZnO. ► This is the first report of an ultra long plasma etch of fluorine onto ZnO surface. - Abstract: Core-shelled structures such as zinc oxide (ZnO) on carbon nanotubes (CNTs) give rise to interesting material properties. In this work, a triple-layered core–shell–shell structure is presented where the effects of fluorine (F) incorporation on the outmost shell of the ZnO-CNT structure are studied. The samples prepared ranged from a short 2 min to a 30 min immersion in carbon tetraflouride (CF 4 ) plasma. In addition, its effects on the electron emission properties also studied and it is shown that the plasma immersions create thinner field emitters with sharp tiny wrinkles giving rise to more electron emission sites and higher enhancement factor. In addition, X-ray photoelectron spectroscopy measurements showed that F ions replace O in ZnO coatings during immersion process, thus increasing the electrical conductivity and shifts the Fermi level of ZnO upwards. Both physical and electronic effects further contribute to a lower threshold field.

Palladium-catalysed electrophilic aromatic C-H fluorination

Science.gov (United States)

Yamamoto, Kumiko; Li, Jiakun; Garber, Jeffrey A. O.; Rolfes, Julian D.; Boursalian, Gregory B.; Borghs, Jannik C.; Genicot, Christophe; Jacq, Jérôme; van Gastel, Maurice; Neese, Frank; Ritter, Tobias

2018-02-01

Aryl fluorides are widely used in the pharmaceutical and agrochemical industries, and recent advances have enabled their synthesis through the conversion of various functional groups. However, there is a lack of general methods for direct aromatic carbon-hydrogen (C-H) fluorination. Conventional methods require the use of either strong fluorinating reagents, which are often unselective and difficult to handle, such as elemental fluorine, or less reactive reagents that attack only the most activated arenes, which reduces the substrate scope. A method for the direct fluorination of aromatic C-H bonds could facilitate access to fluorinated derivatives of functional molecules that would otherwise be difficult to produce. For example, drug candidates with improved properties, such as increased metabolic stability or better blood-brain-barrier penetration, may become available. Here we describe an approach to catalysis and the resulting development of an undirected, palladium-catalysed method for aromatic C-H fluorination using mild electrophilic fluorinating reagents. The reaction involves a mode of catalysis that is unusual in aromatic C-H functionalization because no organometallic intermediate is formed; instead, a reactive transition-metal-fluoride electrophile is generated catalytically for the fluorination of arenes that do not otherwise react with mild fluorinating reagents. The scope and functional-group tolerance of this reaction could provide access to functional fluorinated molecules in pharmaceutical and agrochemical development that would otherwise not be readily accessible.

Self-assembled monolayers of semi-fluorinated thiols and disulfides with a potentially antibacterial terminal fragment on gold surfaces

International Nuclear Information System (INIS)

Thebault, P.; Taffin de Givenchy, E.; Guittard, F.; Guimon, C.; Geribaldi, S.

2008-01-01

Attempts to elaborate the best organized cationic self-assembled monolayers (SAMs) with sulfur derivatives containing potentially bactericidal quaternary ammonium salt moieties have been performed on gold with the final aim to obtain contact-active antibacterial surfaces. Four molecules bearing two hydrocarbon spacers with different lengths between the sulfur atom and the quaternized nitrogen atom, and two different terminal semi-fluorinated alkyl chains have been synthesised and used in view to evaluate their capacity for leading to the highest densities and the highest organization of potentially active molecules on the metal surface. The formation and quality of SAMs characterized by X-ray photoelectron spectroscopy, Internal Reflexion Infra Red Imaging, contact angle and blocking factor measurements depend on the lengths of both the hydrocarbon spacer and terminal perfluorinated chain

An accurate potential energy surface for the F + H{sub 2} → HF + H reaction by the coupled-cluster method

Energy Technology Data Exchange (ETDEWEB)

Chen, Jun; Sun, Zhigang, E-mail: zsun@dicp.ac.cn, E-mail: zhangdh@dicp.ac.cn; Zhang, Dong H., E-mail: zsun@dicp.ac.cn, E-mail: zhangdh@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

2015-01-14

A three dimensional potential energy surface for the F + H{sub 2} → HF + H reaction has been computed by the spin unrestricted coupled cluster method with singles, doubles, triples, and perturbative quadruples [UCCSDT(2){sub Q}] using the augmented correlation-consistent polarised valence quadruple zeta basis set for the fluorine atom and the correlation-consistent polarised valence quadruple zeta basis set for the hydrogen atom. All the calculations are based on the restricted open-shell Hartree-Fock orbitals, together with the frozen core approximations, and the UCCSD(T)/complete basis set (CBS) correction term was included. The global potential energy surface was calculated by fitting the sampled ab initio points without any scaling factor for the correlation energy part using a neutral network function method. Extensive dynamics calculations have been carried out on the potential energy surface. The reaction rate constants, integral cross sections, product rotational states distribution, and forward and backward scattering as a function of collision energy of the F + HD → HF + D, F + HD → DF + H, and F + H{sub 2} reaction, were calculated by the time-independent quantum dynamics scattering theory using the new surface. The satisfactory agreement with the reported experimental observations previously demonstrates the accuracy of the new potential energy surface.

Layer-by-Layer Assembly of Fluorine-Free Polyelectrolyte-Surfactant Complexes for the Fabrication of Self-Healing Superhydrophobic Films.

Science.gov (United States)

Wu, Mengchun; An, Ni; Li, Yang; Sun, Junqi

2016-11-29

Fluorine-free self-healing superhydrophobic films are of significance for practical applications because of their extended service life and cost-effective and eco-friendly preparation process. In this study, we report the fabrication of fluorine-free self-healing superhydrophobic films by layer-by-layer (LbL) assembly of poly(sodium 4-styrenesulfonate) (PSS)-1-octadecylamine (ODA) complexes (PSS-ODA) and poly(allylamine hydrochloride) (PAH)-sodium dodecyl sulfonate (SDS) (PAH-SDS) complexes. The wettability of the LbL-assembled PSS-ODA/PAH-SDS films depends on the film structure and can be tailored by changing the NaCl concentration in aqueous dispersions of PSS-ODA complexes and the number of film deposition cycles. The freshly prepared PSS-ODA/PAH-SDS film with micro- and nanoscaled hierarchical structures is hydrophilic and gradually changes to superhydrophobic in air because the polyelectrolyte-complexed ODA and SDS surfactants tend to migrate to the film surface to cover the film with hydrophobic alkyl chains to lower its surface energy. The large amount of ODA and SDS surfactants loaded in the superhydrophobic PSS-ODA/PAH-SDS films and the autonomic migration of these surfactants to the film surface endow the resultant superhydrophobic films with an excellent self-healing ability to restore the damaged superhydrophobicity. The self-healing superhydrophobic PSS-ODA/PAH-SDS films are mechanically robust and can be deposited on various flat and nonflat substrates. The LbL assembly of oppositely charged polyelectrolyte-surfactant complexes provides a new way for the fabrication of fluorine-free self-healing superhydrophobic films with satisfactory mechanical stability, enhanced reliability, and extended service life.

Fluorinated tracers for imaging cancer with positron emission tomography

International Nuclear Information System (INIS)

Couturier, Olivier; Chatal, Jean-Francois; Luxen, Andre; Vuillez, Jean-Philippe; Rigo, Pierre; Hustinx, Roland

2004-01-01

2-[ 18 F]fluoro-2-deoxy-d-glucose (FDG) is currently the only fluorinated tracer used in routine clinical positron emission tomography (PET). Fluorine-18 is considered the ideal radioisotope for PET imaging owing to the low positron energy (0.64 MeV), which not only limits the dose rate to the patient but also results in a relatively short range of emission in tissue, thereby providing high-resolution images. Further, the 110-min physical half-life allows for high-yield radiosynthesis, transport from the production site to the imaging site and imaging protocols that may span hours, which permits dynamic studies and assessment of potentially fairly slow metabolic processes. The synthesis of fluorinated tracers as an alternative to FDG was initially tested using nucleophilic fluorination of the molecule, as performed when radiolabelling with iodine-124 or bromide-76. However, in addition to being long, with multiple steps, this procedure is not recommended for bioactive molecules containing reactive groups such as amine or thiol groups. Radiochemical yields are also often low. More recently, radiosynthesis from prosthetic group precursors, which allows easier radiolabelling of biomolecules, has led to the development of numerous fluorinated tracers. Given the wide availability of 18 F, such tracers may well develop into important routine tracers. This article is a review of the literature concerning fluorinated radiotracers recently developed and under investigation for possible PET imaging in cancer patients. Two groups can be distinguished. The first includes ''generalist'' tracers, i.e. tracers amenable to use in a wide variety of tumours and indications, very similar in this respect to FDG. These are tracers for non-specific cell metabolism, such as protein synthesis, amino acid transport, nucleic acid synthesis or membrane component synthesis. The second group consists of ''specific'' tracers for receptor expression (i.e. oestrogens or somatostatin), cell

Experimental study of the plasma fluorination of Y-Ba-Cu-O thin films

CERN Document Server

Li Qi; Ji Zheng Ming; Feng Yi Jun; Kang Lin; Yang Sen Zu; Wu Pei Heng; Wang Xiao Shu; Ye Yuda

2002-01-01

The authors have experimentally studied the surface modifications of Y-Ba-Cu-O (YBCO) thin films using CF sub 4 plasma. The intensity of the plasma fluorination was controlled by changing the biasing voltage and the time of the plasma treatment. Microstructural analyses reveal that the oxygen content of the YBCO thin films was changed. Transport measurements of sufficient fluorinated YBCO films imply that the films changed totally into an oxygen-deficient semi-conducting state. From these experimental results, the authors believe that plasma fluorination is quite a useful method to form controllable a thin barrier layer in fabricating interface engineered junctions and to form a stable narrow weak-link region in fabricating planar superconductor-normal-superconductor junctions

Ultrahigh volumetric capacitance and cyclic stability of fluorine and nitrogen co-doped carbon microspheres

Science.gov (United States)

Zhou, Junshuang; Lian, Jie; Hou, Li; Zhang, Junchuan; Gou, Huiyang; Xia, Meirong; Zhao, Yufeng; Strobel, Timothy A.; Tao, Lu; Gao, Faming

2015-09-01

Highly porous nanostructures with large surface areas are typically employed for electrical double-layer capacitors to improve gravimetric energy storage capacity; however, high surface area carbon-based electrodes result in poor volumetric capacitance because of the low packing density of porous materials. Here, we demonstrate ultrahigh volumetric capacitance of 521 F cm-3 in aqueous electrolytes for non-porous carbon microsphere electrodes co-doped with fluorine and nitrogen synthesized by low-temperature solvothermal route, rivaling expensive RuO2 or MnO2 pseudo-capacitors. The new electrodes also exhibit excellent cyclic stability without capacitance loss after 10,000 cycles in both acidic and basic electrolytes at a high charge current of 5 A g-1. This work provides a new approach for designing high-performance electrodes with exceptional volumetric capacitance with high mass loadings and charge rates for long-lived electrochemical energy storage systems.

The uranyl cation as a visible-light photocatalyst for C(sp{sup 3})-H fluorination

Energy Technology Data Exchange (ETDEWEB)

West, Julian G.; Bedell, T. Aaron; Sorensen, Erik J. [Department of Chemistry, Princeton University, Princeton, NJ (United States)

2016-07-25

The fluorination of unactivated C(sp{sup 3})-H bonds remains a desirable and challenging transformation for pharmaceutical, agricultural, and materials scientists. Previous methods for this transformation have used bench-stable fluorine atom sources; however, many still rely on the use of UV-active photocatalysts for the requisite high-energy hydrogen atom abstraction event. Uranyl nitrate hexahydrate is described as a convenient, hydrogen atom abstraction catalyst that can mediate fluorinations of certain alkanes upon activation with visible light. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Nucleophilic Fluorination Reactions in Novel Reaction Media for 18F-Fluorine Labeling Method

International Nuclear Information System (INIS)

Kim, Dong Wook; Jeong, Hwan Jeong; Lim, Seok Tae; Sohn, Myung Hee

2009-01-01

Noninvasive imaging of molecular and biological processes in living subjects with positron emission tomography (PET) provides exciting opportunities to monitor metabolism and detect diseases in humans. Measuring these processes with PET requires the preparation of specific molecular imaging probes labeled with 18F-fluorine. In this review we describe recent methods and novel trends for the introduction of 18 F-fluorine into molecules which in turn are intended to serve as imaging agents for PET study. Nucleophilic 18 F-fluorination of some halo- and mesyloxyalkanes to the corresponding 18 F-fluoroalkanes with 18 F-fluoride obtained from an 18 O(p,n) 18 F reaction, using novel reaction media system such as an ionic liquidor tert-alcohol, has been studied as a new method for 18 F-fluorine labeling. Ionic liquid method is rapid and particularly convenient because 18 F-fluoride in H 2 O can be added directly to the reaction media, obviating the careful drying that is typically required for currently used radiofluorination methods. The nonpolar protic tert-alcohol enhances the nucleophilicity of the fluoride ion dramatically in the absence of any kind of catalyst, greatly increasing the rate of the nucleophilic fluorination and reducing formation of byproducts compared with conventional methods using dipolar aprotic solvents. The great efficacy of this method is a particular advantage in labeling radiopharmaceuticals with 18 F-fluorine for PET imaging, and it is illustrated by the synthesis of 18 F-fluoride radiolabeled molecular imaging probes, such as 18 F-FDG, 18 F-FLT, 18 F-FP-CIT, and 18 F-FMISO, in high yield and purity and in shorter times compared to conventional syntheses

Structural analysis of fluorine-containing bioactive glass nanoparticles synthesized by sol-gel route assisted by ultrasound energy.

Science.gov (United States)

Lins, Carolina E C; Oliveira, Agda A R; Gonzalez, Ismael; Macedo, Waldemar A A; Pereira, Marivalda M

2018-01-01

In the last decades, studies about the specific effects of bioactive glass on remineralization of dentin were the focus of attention, due to their excellent regenerative properties in mineralized tissues. The incorporation of Fluorine in bioactive glass nanoparticles may result in the formation of fluorapatite (FAP), which is chemically more stable than hydroxyapatite or carbonated hydroxyapatite, and therefore is of interest for dental applications. The aim of this study was to synthesize and characterize a new system of Fluorine-containing bioactive glass nanoparticles (BGNPF). A sol-gel route assisted by ultrasound was used for the synthesis of BGNPF. The particles obtained were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), X-ray diffraction (XRD), dynamic light scattering (DLS), nitrogen adsorption, and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed that the particles are quite uniform spherical nanostructures, occurring agglomeration or partial sinterization of the particulate system after heat treatment. XRD and XPS analysis results suggest the formation of fluorapatite crystals embedded within the matrix of the bioactive glass nanoparticles. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 360-366, 2018. © 2017 Wiley Periodicals, Inc.

Enhancement of the Stability of Fluorine Atoms on Defective Graphene and at Graphene/Fluorographene Interface.

Science.gov (United States)

Ao, Zhimin; Jiang, Quanguo; Li, Shuang; Liu, Hao; Peeters, Francois M; Li, Sean; Wang, Guoxiu

2015-09-09

Fluorinated graphene is one of the most important derivatives of graphene and has been found to have great potential in optoelectronic and photonic nanodevices. However, the stability of F atoms on fluorinated graphene under different conditions, which is essential to maintain the desired properties of fluorinated graphene, is still unclear. In this work, we investigate the diffusion of F atoms on pristine graphene, graphene with defects, and at graphene/fluorographene interfaces by using density functional theory calculations. We find that an isolated F atom diffuses easily on graphene, but those F atoms can be localized by inducing vacancies or absorbates in graphene and by creating graphene/fluorographene interfaces, which would strengthen the binding energy of F atoms on graphene and increase the diffusion energy barrier of F atoms remarkably.

Effect of deposition temperature on the bonding configurations and properties of fluorine doped silicon oxide film

International Nuclear Information System (INIS)

Lu, Wei-Lun; Kuo, Ting-Wei; Huang, Chun-Hsien; Wang, Na-Fu; Tsai, Yu-Zen; Wang, Ming-Wei; Hung, Chen-I.; Houng, Mau-Phon

2011-01-01

In our study, fluorine-doped silicon oxide (SiOF) films were prepared using a mixture of SiH 4 , N 2 O, and CF 4 in a conventional plasma enhanced chemical vapor deposition system at various deposition temperatures. Deposition behaviors are determined by the deposition temperature. Our results show that for temperatures below 300 deg. C the process is surface-reaction-limited controlled, but becomes diffusion-limited when the deposition temperature exceeds 300 deg. C. The surface topography images obtained using an atomic force microscope show that a large amount of free volume space was created in the film with a low temperature deposition. The optical microscope and secondary ion mass spectrometer analyses show that precipitates were produced at the near-surface at the deposition temperature of 150 deg. C with a higher fluorine concentration of 2.97 at.%. Our results show that the properties of the SiOF film are controlled not only by the free volume space but also by the fluorine concentration. An optimal SiOF film prepared at a temperature of 200 deg. C shows a low dielectric constant of 3.55, a leakage current of 1.21 x 10 -8 A/cm 2 at 1 MV/cm, and a fluorine concentration of 2.5 at.%.

Novel Fluorinated Tensioactive Extractant Combined with Flotation for Decontamination of Extractant Residual during Solvent Extraction

Science.gov (United States)

Wu, Xue; Chang, Zhidong; Liu, Yao; Choe, Chol Ryong

2017-12-01

Solvent-extraction is widely used in chemical industry. Due to the amphiphilic character, a large amount of extractant remains in water phase, which causes not only loss of reagent, but also secondary contamination in water phase. Novel fluorinated extractants with ultra-low solubility in water were regarded as effective choice to reduce extractant loss in aqueous phase. However, trace amount of extractant still remained in water. Based on the high tensioactive aptitude of fluorinated solvent, flotation was applied to separate fluorinated extractant remaining in raffinate. According to the data of surface tension measurement, the surface tension of solution was obviously decreased with the addition of fluorinated extractant tris(2,2,3,3,4,4,5,5-octafluoropentyl) phosphate (FTAP). After flotation, the FTAP dissolved in water can be removed as much as 70%, which proved the feasibility of this key idea. The effects of operation time, gas velocity, pH and salinity of bulk solution on flotation performance were discussed. The optimum operating parameters were determined as gas velocity of 12ml/min, operating time of 15min, pH of 8.7, and NaCl volume concentration of 1.5%, respectively. Moreover, adsorption process of FTAP on bubble surface was simulated by ANSYS VOF model using SIMPLE algorithm. The dynamic mechanism of flotation was also theoretically investigated, which can be considered as supplement to the experimental results.

Corrosion resistant materials for fluorine and hydrogen fluoride

International Nuclear Information System (INIS)

Hauffe, K.

1984-01-01

Aluminum and Duralumin are resistant against fluorine and hydrogen fluoride up to 600 and 700 K, respectively. The resistance of nickel and its alloys, particularly monel, against fluorine and hydrogen fluoride is fairly good up to 900 and 800 K. During the attack of nickel-chromium alloys by fluorine between 1000 and 1300 K, it appears an inner fluorination similarly to the inner oxidation. The resistance of titanium in water-free liquid fluorine at lower temperatures with -1 is comparable to that of nickel and monel. However, the corrosion of titanium in gaseous fluorine amounts at 377 K only 0,0082 mm.a -1 . In spite of their limited resistance against fluorine and hydrogen fluoride, very pure molybdenum and tungsten are employed as construction materials in the rocket technology because of their large strength at high temperatures if fluorine-hydrogen and fluorine-hydrazine flames are used. Lanthanum and calcium borides are only little attacked by fluorine hydrazine flames between 1400 and 1800 K; they are superior to all special grade alloys. The same is true in a lower temperature region (290-400 K) with fluorcarbon resins. Organic materials substitute in increasing extent metal alloys and non-metal inorganic materials. (orig.) [de

Corrosion resistant materials for fluorine and hydrogen fluoride

Energy Technology Data Exchange (ETDEWEB)

Hauffe, K.

1984-12-01

Aluminum and Duralumin are resistant against fluorine and hydrogen fluoride up to 600 and 700 K, respectively. The resistance of nickel and its alloys, particularly monel, against fluorine and hydrogen fluoride is fairly good up to 900 and 800 K. During the attack of nickel-chromium alloys by fluorine between 1000 and 1300 K, it appears an inner fluorination similarly to the inner oxidation. The resistance of titanium in water-free liquid fluorine at lower temperatures with <0,3 mm.a/sup -1/ is comparable to that of nickel and monel. However, the corrosion of titanium in gaseous fluorine amounts at 377 K only 0,0082 mm.a/sup -1/. In spite of their limited resistance against fluorine and hydrogen fluoride, very pure molybdenum and tungsten are employed as construction materials in the rocket technology because of their large strength at high temperatures if fluorine-hydrogen and fluorine-hydrazine flames are used. Lanthanum and calcium borides are only little attacked by fluorine hydrazine flames between 1400 and 1800 K; they are superior to all special grade alloys. The same is true in a lower temperature region (290-400 K) with fluorcarbon resins. Organic materials substitute in increasing extent metal alloys and non-metal inorganic materials.

Electrolytes including fluorinated solvents for use in electrochemical cells

Science.gov (United States)

Tikhonov, Konstantin; Yip, Ka Ki; Lin, Tzu-Yuan

2015-07-07

Provided are electrochemical cells and electrolytes used to build such cells. The electrolytes include ion-supplying salts and fluorinated solvents capable of maintaining single phase solutions with the salts at between about -30.degree. C. to about 80.degree. C. The fluorinated solvents, such as fluorinated carbonates, fluorinated esters, and fluorinated esters, are less flammable than their non-fluorinated counterparts and increase safety characteristics of cells containing these solvents. The amount of fluorinated solvents in electrolytes may be between about 30% and 80% by weight not accounting weight of the salts. Fluorinated salts, such as fluoroalkyl-substituted LiPF.sub.6, fluoroalkyl-substituted LiBF.sub.4 salts, linear and cyclic imide salts as well as methide salts including fluorinated alkyl groups, may be used due to their solubility in the fluorinated solvents. In some embodiments, the electrolyte may also include a flame retardant, such as a phosphazene or, more specifically, a cyclic phosphazene and/or one or more ionic liquids.

Effect of the fluorinated groups on nematic liquid crystal alignment on monomer crosslinked film

International Nuclear Information System (INIS)

Yu Tao; Peng Zenghui; Ruan Shengping; Xuan Li

2004-01-01

It was found in this work that photosensitive monomers, bisphenol A dicinnamate ester and hexafluorobiphenol a dicinnamate ester were crosslinked under irradiation of linearly polarized ultraviolet light. The exposed films induced homogeneous and homeotropic alignment of liquid crystals (LC), respectively. We verified through experiments that it was fluorinated groups that caused the generation of LC homeotropic alignment on the crosslinked film. Photoreaction process was revealed by Fourier transform infrared spectra. There was no clear morphological anisotropy on these aligned films observed through atomic force microscope analysis. The surface energies were measured and homeotropic alignment reason was discussed in this work

Barium coordination polymers based on fluorinated and fluorine-free benzene-dicarboxylates: Mechanochemical synthesis and spectroscopic characterization

Science.gov (United States)

Al-Terkawi, Abdal-Azim; Scholz, Gudrun; Emmerling, Franziska; Kemnitz, Erhard

2018-05-01

A series of new Ba-based coordination polymers (CPs) were mechanochemically synthesized by milling Ba-hydroxide samples with perfluorinated and fluorine-free benzene-dicarboxylic acids, including tetrafluoroisophthalic acid (H2mBDC-F4), tetrafluorophthalic acid (H2oBDC-F4), isophthalic acid (H2mBDC) and phthalic acid (H2oBDC). The new fluorinated CPs: [Ba(mBDC-F4)·0.5H2O] (1) and [Ba(oBDC-F4)·1.5H2O] (2) are compared to their nonfluorinated counterparts: [Ba(mBDC)·2.5H2O] (3), and [Ba(oBDC)·1H2O] (4). These materials are thoroughly characterized using powder X-ray diffraction. The products obtained by milling are all hydrated but vary in their water contents. Compositions and local structures are investigated by elemental analysis, thermal analysis, MAS NMR and attenuated total reflection-infrared spectroscopy. These materials exhibit high thermal stabilities but small surface areas that remain unchanged even after thermal treatments.

Cationic fluorinated polymer binders for microbial fuel cell cathodes

KAUST Repository

Chen, Guang; Wei, Bin; Logan, Bruce E.; Hickner, Michael A.

2012-01-01

Fluorinated quaternary ammonium-containing polymers were used as catalyst binders in microbial fuel cell (MFC) cathodes. The performance of the cathodes was examined and compared to NAFION ® and other sulfonated aromatic cathode catalyst binders using linear sweep voltammetry (LSV), impedance spectroscopy, and performance tests in single chamber air-cathode MFCs. The cathodes with quaternary ammonium functionalized fluorinated poly(arylene ether) (Q-FPAE) binders showed similar current density and charge transfer resistance (R ct) to cathodes with NAFION ® binders. Cathodes containing either of these fluorinated binders exhibited better electrochemical responses than cathodes with sulfonated or quaternary ammonium-functionalized RADEL ® poly(sulfone) (S-Radel or Q-Radel) binders. After 19 cycles (19 d), the power densities of all the MFCs declined compared to the initial cycles due to biofouling at the cathode. MFC cathodes with fluorinated polymer binders (1445 mW m -2, Q-FPAE-1.4-H; 1397 mW m -2, Q-FPAE-1.4-Cl; 1277 mW m -2, NAFION ®; and 1256 mW m -2, Q-FPAE-1.0-Cl) had better performance than those with non-fluorinated polymer binders (880 mW m -2, S-Radel; 670 mW m -2, Q-Radel). There was a 15% increase in the power density using the Q-FPAE binder with a 40% higher ion exchange capacity (Q-FPAE-1.4-H compared to Q-FPAE-1.0-Cl) after 19 cycles of operation, but there was no effect on the power production due to counter ions in the binder (Cl -vs. HCO 3 -). The highest-performance cathodes (NAFION ® and Q-FPAE binders) had the lowest charge transfer resistances (R ct) in fresh and in fouled cathodes despite the presence of thick biofilms on the surface of the electrodes. These results show that fluorinated binders may decrease the penetration of the biofilm and associated biopolymers into the cathode structure, which helps to combat MFC performance loss over time. © 2012 The Royal Society of Chemistry.

Synthetic biology approaches to fluorinated polyketides.

Science.gov (United States)

Thuronyi, Benjamin W; Chang, Michelle C Y

2015-03-17

The catalytic diversity of living systems offers a broad range of opportunities for developing new methods to produce small molecule targets such as fuels, materials, and pharmaceuticals. In addition to providing cost-effective and renewable methods for large-scale commercial processes, the exploration of the unusual chemical phenotypes found in living organisms can also enable the expansion of chemical space for discovery of novel function by combining orthogonal attributes from both synthetic and biological chemistry. In this context, we have focused on the development of new fluorine chemistry using synthetic biology approaches. While fluorine has become an important feature in compounds of synthetic origin, the scope of biological fluorine chemistry in living systems is limited, with fewer than 20 organofluorine natural products identified to date. In order to expand the diversity of biosynthetically accessible organofluorines, we have begun to develop methods for the site-selective introduction of fluorine into complex natural products by engineering biosynthetic machinery to incorporate fluorinated building blocks. To gain insight into how both enzyme active sites and metabolic pathways can be evolved to manage and select for fluorinated compounds, we have studied one of the only characterized natural hosts for organofluorine biosynthesis, the soil microbe Streptomyces cattleya. This information provides a template for designing engineered organofluorine enzymes, pathways, and hosts and has allowed us to initiate construction of enzymatic and cellular pathways for the production of fluorinated polyketides.

Examination of fluorination effect on physical properties of saturated long-chain alcohols by DSC and Langmuir monolayer.

Science.gov (United States)

Nakahara, Hiromichi; Nakamura, Shohei; Okahashi, Yoshinori; Kitaguchi, Daisuke; Kawabata, Noritake; Sakamoto, Seiichi; Shibata, Osamu

2013-02-01

Partially fluorinated long-chain alcohols have been newly synthesized from a radical reaction, which is followed by a reductive reaction. The fluorinated alcohols have been investigated by differential scanning calorimetry (DSC) and compression isotherms in a Langmuir monolayer state. Their melting points increase with an increase in chain length due to elongation of methylene groups. However, the melting points for the alcohols containing shorter fluorinated moieties are lower than those for the typical hydrogenated fatty alcohols. Using the Langmuir monolayer technique, surface pressure (π)-molecular area (A) and surface potential (ΔV)-A isotherms of monolayers of the fluorinated alcohols have been measured in the temperature range from 281.2 to 303.2K. In addition, a compressibility modulus (Cs(-1)) is calculated from the π-A isotherms. Four kinds of the alcohol monolayers show a phase transition (π(eq)) from a disordered to an ordered state upon lateral compression. The π(eq) values increase linearly with increasing temperatures. A slope of π(eq) against temperature for the alcohols with shorter fluorocarbons is unexpectedly larger than that for the corresponding fatty alcohols. Generally, fluorinated amphiphiles have a greater thermal stability (or resistance), which is a characteristic of highly fluorinated or perfluorinated compounds. Herein, however, the alcohols containing perfluorobutylated and perfluorohexylated chains show the irregular thermal behavior in both the solid and monolayer states. Copyright © 2012 Elsevier B.V. All rights reserved.

Chemical forms of the fluorine, chlorine, oxygen and carbon in coal fly ash and their correlations with mercury retention

Energy Technology Data Exchange (ETDEWEB)

Deng, Shuang [State Key Laboratory of Environmental Criteria and Risk Assessment (China); Research Academy of Environmental Sciences, Beijing 100012 (China); Shu, Yun [Research Academy of Environmental Sciences, Beijing 100012 (China); Li, Songgeng, E-mail: sgli@ipe.ac.cn [State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Tian, Gang; Huang, Jiayu [Research Academy of Environmental Sciences, Beijing 100012 (China); Zhang, Fan, E-mail: zhangfan5188@vip.sina.com [Research Academy of Environmental Sciences, Beijing 100012 (China)

2016-01-15

Highlights: • Chlorine and fluorine are present mainly in an inorganic form on ash. • Correlations of carbon–oxygen complexes with mercury retention are established. • Concentrations of carbon–oxygen complexes on ash are related to coal type. • No effect of fluorine on mercury retention is observed. • Chlorine, fluorine and carbon in ash are enriched on surface. - Abstract: Fly ashes recovered from the particulate control devices at six pulverized coal boiler unites of China, are studied using an X-ray photoelectron spectroscopy (XPS) with a particular focus on the functionalities of fluorine (F), chlorine (Cl), carbon and oxygen on fly ash. It is found that the inorganic forms of F and Cl are predominant on the ash surface in comparison with their organics, and the proportion of organic Cl is relatively higher than that of organic F. Similar results are also obtained in the bulk by correlating the F and Cl contents with those of the unburnt carbon and other compositions in ash. Strong correlations of mercury retention with surface carbon–oxygen functional groups indicate that the C=O, OH/C−O and (O−C=O)−O on surface are of significant importance for mercury retention in fly ash. Their surface concentrations are related to coal type. The presence of Cl in fly ash helps with mercury retention. No obvious effect of F is observed.

Fluorine-plasma surface treatment for gate forward leakage current reduction in AlGaN/GaN HEMTs

International Nuclear Information System (INIS)

Chen Wanjun; Zhang Jing; Zhang Bo; Chen, Kevin Jing

2013-01-01

The gate forward leakage current in AlGaN/GaN high electron mobility transistors (HEMTs) is investigated. It is shown that the current which originated from the forward biased Schottky-gate contributed to the gate forward leakage current. Therefore, a fluorine-plasma surface treatment is presented to induce the negative ions into the AlGaN layer which results in a higher metal—semiconductor barrier. Consequently, the gate forward leakage current shrinks. Experimental results confirm that the gate forward leakage current is decreased by one order magnitude lower than that of HEMT device without plasma treatment. In addition, the DC characteristics of the HEMT device with plasma treatment have been studied. (semiconductor devices)

Kinetics study of the fluorination of uranium tetrafluoride in a fluidized bed reactor

International Nuclear Information System (INIS)

Khani, M.H.; Pahlavanzadeh, H.; Ghannadi, M.

2008-01-01

The kinetics of reaction of the uranium tetrafluoride conversion to the uranium hexafluoride with fluorine gas taking place in a fluidized bed reactor operating in industrial conditions have been studied. The external and internal diffusion effects are investigated by Mears and Weisz-Prater criterions. The kinetic equation for the fluorination of uranium tetrafluoride is developed in the absence of diffusional limitation using an integral method by assuming that the gas flow is of plug or perfectly mixed type. A good agreement is observed between the experimental data and a first-order model with respect to fluorine in the CSTR system. The activation energy of the reaction and the pre-exponential factor are obtained using analytical results from a better model

Conceptual design of a continuous fluorinator experimental facility (CFEF)

International Nuclear Information System (INIS)

Lindauer, R.B.; Hightower, J.R. Jr.

1976-07-01

A conceptual design has been made of a circulating salt system, consisting principally of a fluorinator and reduction column, to demonstrate uranium removal from the salt by fluorination. The fluorinator vessel wall will be protected from fluorine corrosion by a frozen salt film. The circulating salt in the fluorinator will be kept molten by electrical heating that simulates fission product heating in an actual MSBR system

Fabrication and characterization of stable superhydrophobic fluorinated-polyacrylate/silica hybrid coating

International Nuclear Information System (INIS)

Li, Kunquan; Zeng, Xingrong; Li, Hongqiang; Lai, Xuejun

2014-01-01

Graphical abstract: - Highlights: • The superhydrophobic PFA/SiO 2 coating was successfully fabricated by spraying. • The synthesized PFA latex showed core–shell structure and good dispersion. • The PFA/SiO 2 coating showed good resistance to acid and base, weather and heat. • The superhydrophobic coating could be fabricated on various substrates. - Abstract: The core–shell fluorinated-polyacrylate (PFA) emulsion was synthesized through emulsion polymerization method and the superhydrophobic PFA/SiO 2 hybrid coating was successfully fabricated on the slide glass by spraying the mixture of PFA emulsion and hydrophobic SiO 2 particles using ethanol as cosolvent. The PFA emulsion was characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), water contact angle (WCA), transmission electron microscopy (TEM), and the effects of SiO 2 content on the wetting behavior and surface morphology of PFA/SiO 2 hybrid coating were investigated. To evaluate the stability of the hybrid coating, the acid and base resistance, weatherability and thermal stability were also studied. Results showed that the obtained PFA latex exhibited a core–shell structure with a particle size of 134.1 nm and a narrow polydispersity of 0.03. With the increase of dodecafluoroheptyl methacrylate (DFMA) content in the latex shell from 0 wt% to 31.8 wt%, the WCA of the PFA film enlarged from 85° to 104°, indicating that the introduction of fluorinated monomer was effective in reducing the surface energy. By adding different amount of SiO 2 particles, the surface morphology and wetting behavior of the PFA/SiO 2 hybrid coatings could be controlled. When the mass ratio of SiO 2 to PFA emulsion was 0.2, the surface roughness (Rq) increased to 173.6 nm and the wetting behavior of the surface became superhydrophobic with a WCA of 153°, resulted from the corporation of low surface energy and the binary nano/microstructure on the surface. The as-prepared PFA

Production and transport chemistry of atomic fluorine in remote plasma source and cylindrical reaction chamber

International Nuclear Information System (INIS)

Gangoli, S P; Johnson, A D; Fridman, A A; Pearce, R V; Gutsol, A F; Dolgopolsky, A

2007-01-01

Increasingly, NF 3 -based plasmas are being used in semiconductor manufacturing to clean chemical vapour deposition (CVD) chambers. With advantages such as faster clean times, substantially lower emissions of gases having high global warming potentials, and reduced chamber damage, NF 3 plasmas are now favoured over fluorocarbon-based processes. Typically, a remote plasma source (RPS) is used to dissociate the NF 3 gas and produce atomic fluorine that etches the CVD residues from the chamber surfaces. However, it is important to efficiently transport F atoms from the plasma source into the process chamber. The current work is aimed at understanding and improving the key processes involved in the production and transport of atomic fluorine atoms. A zero-dimensional model of NF 3 dissociation and F production chemistry in the RPS is developed based on various known and derived plasma parameters. Additionally, a model describing the transport of atomic fluorine is proposed that includes both physical (diffusion, adsorption and desorption) and chemical processes (surface and three-body volume recombination). The kinetic model provides an understanding of the impact of chamber geometry, gas flow rates, pressure and temperature on fluorine recombination. The plasma-kinetic model is validated by comparing model predictions (percentage F atom density) with experimental results (etch rates)

Evaluation of the diffusion coefficient of fluorine during the electropolishing of niobium

Directory of Open Access Journals (Sweden)

Hui Tian

2010-08-01

Full Text Available Future accelerators require unprecedented cavity performance, which is strongly influenced by interior surface nanosmoothness. Electropolishing (EP is the technique of choice being developed for high-field superconducting radio frequency (SRF cavities. Previous study has shown that the mechanism of Nb electropolishing proceeds by formation and dissolution of a compact salt film under fluorine diffusion-limited mass transport control. We pursue an improved understanding of the microscopic conditions required for optimum surface finishing. The viscosity of the standard electrolyte has been measured using a commercial viscometer, and the diffusion coefficient of fluorine was derived at a variety of temperatures from 0 to 50°C using a Nb rotating disk electrode. In addition, data indicate that electrode kinetics becomes competitive with the mass transfer current limitation and increases dramatically with temperature. These findings are expected to guide the optimization of EP process parameters for achieving controlled, reproducible, and uniform nanosmooth surface finishing of SRF cavities.

The effect of fluorine and homeopathic medicines in rats fed cariogenic diet.

Science.gov (United States)

Almeida, N T; Dalmeida, V; Pustiglione, M

2004-07-01

Although some sectors of dentistry have benefited from technological advances, dental caries is still a major problem. Prevention and treatment of dental caries by fluorine is considered a major advance in public health. Nevertheless fluorosis, caused by ingestion of excessive amounts of fluorine during the period of teeth formation, is of great concern. In accordance with the homeopathic doctrine, minimum doses of fluorine and other substances could prevent and/or treat caries. In this experiment, we compared the preventive action of fluorine and evaluated the effect of homeopathic medicines on the teeth of rats fed a cariogenic diet. None of the groups included in this study developed caries. However, microscopy revealed the presence of precipitate and/or deposit in the groups treated with homeopathic medicines. This phenomenon might be due to deposit in the dental surface or precipitation of bacterial plaque or calcium salts. It was not possible to identify the composition of the deposit/precipitate due for technical reasons. In one of the groups treated with homeopathic medicines fur loss was observed in 40% of animals. These reactions might be caused due to the action of the homeopathic medicines.

β-diketones containing oxygen atom in fluorinated radical

International Nuclear Information System (INIS)

Shivanyuk, A.F.; Kudryavtseva, L.S.; Lozinskij, M.O.; Neplyuev, V.M.; Fialkov, Yu.A.; Bratolyubova, A.G.

1981-01-01

The synthesis of a number of new aliphatic fluorinated β- diketones containing oxygen atom in fluorinated radical of linear or cyclic structure is described. The reaction of combination with aryldiazonium salts resulting in the formation of corresponding arylhydrazones of fluorinated triketones is studied. It is shown that as a result of arylhydrazone condensation with hydroxylamine, hydrazine and its substituted derivatives the fluorine-containing derivatives of isoxazol and pyrazol are formed [ru

beta. -diketones containing oxygen atom in fluorinated radical

Energy Technology Data Exchange (ETDEWEB)

Shivanyuk, A.F.; Kudryavtseva, L.S.; Lozinskij, M.O.; Neplyuev, V.M.; Fialkov, Yu.A.; Bratolyubova, A.G. (AN Ukrainskoj SSR, Kiev. Inst. Organicheskoj Khimii)

1981-10-01

The synthesis of a number of new aliphatic fluorinated ..beta..-diketones containing oxygen atom in fluorinated radical of linear or cyclic structure is described. The reaction of combination with aryldiazonium salts resulting in the formation of corresponding arylhydrazones of fluorinated triketones is studied. It is shown that as a result of arylhydrazone condensation with hydroxylamine, hydrazine and its substituted derivatives the fluorine-containing derivatives of isoxazol and pyrazol are formed.

Rapid general microdetermination of fluorine

NARCIS (Netherlands)

Leuven, H.C.E. van; Rotscheid, G.J.; Buis, W.J.

1979-01-01

A rapid micromethod for the determination of fluorine in a wide variety of materials has been developed. The method is based on the liberation of the fluorine (as HF) from the sample by means of pyrohydrolysis with steam at 1120?? C, The amount of fluoride in the condensate is subsequently measured

XPS and surface resistivity measurements of plasma - treated FEP co-polymer

International Nuclear Information System (INIS)

Pitrus, R.K.; Brack, N.; Liesegang, J.; Pigram, P.J.

2002-01-01

Full text: Fluorinated polymers such as fluorinated ethylene propylene (FEP) and poly(tetrafluoroethylene) (PTFE) play an important role in many applications due to their many desirable properties such as chemical resistivity, inertness, electrical stability and low dielectric constant; however, one disadvantage of fluorinated polymers is their extreme surface hydrophobicity. Previous studies show that plasma treatment will modify the surface by increasing the surface free energy and also offer a rapid and convenient method for pre-treating the polymers for many purposes. This paper, through resistivity and XPS (x-ray photoelectron spectroscopy) measurements, attempts to discover basic effects of such plasma treatment. Fluorinated ethylene propylene (FEP) co-polymer film of (0.05) mm thickness (obtained commercially) and with the following structure (CF 2 -CF 2 )-(CF(CF 3 )CF 2 )- was used. A suitable cleaning procedure was used to remove adventitious carbon from the surface. XPS has been used to study FEP film properties. The spectra of XPS were analyzed with the main focus on carbon and fluorine as they compose the elemental component of FEP film. A value of 2.05 was obtained for the F/C ratio, which is slightly higher than the theoretical F/C value estimated from the chemical structure of FEP (F/C 2). The clean film was then air plasma treated (pressure 10 -1 torr and power 30W) for various treatment times to produce a higher energy fluoropolymer surface. XPS studies investigated changes to the polymer surface and determined that oxidation occurs on the FEP surface. The oxidation reactions on the FEP surface form oxygen functional groups such as C-O and C=O groups. The results also show that the percentage of CF 2 and CF 3 in the co-polymer surface decreased with exposure time and the percentage of CF, C-C, C-O and C=O increased. There is a sharp decrease in F/C ratio and increase in O/C ratio. In addition to XPS, the resistivity of FEP-film was measured by a

Orbital momentum profiles and binding energy spectra for the complete valence shell of molecular fluorine

Energy Technology Data Exchange (ETDEWEB)

Zheng, Y.; Brion, C.E. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemistry; Brunger, M.J.; Zhao, K.; Grisogono, A.M.; Braidwood, S.; Weigold, E. [Flinders Univ. of South Australia, Adelaide, SA (Australia). Electronic Structure of Materials Centre; Chakravorty, S.J.; Davidson, E.R. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry; Sgamellotti, A. [Univ di Perugia (Italy). Dipartimento di Chimica; von Niessen, W. [Technische Univ. Braunschweig (Germany). Inst fuer Physikalische

1996-01-01

The first electronic structural study of the complete valence shell binding energy spectrum of molecular fluorine, encompassing both the outer and inner valence regions, is reported. These binding energy spectra as well as the individual orbital momentum profiles have been measured using an energy dispersive multichannel electron momentum spectrometer at a total energy of 1500 eV, with an energy resolution of 1.5 eV and a momentum resolution of 0.1 a.u. The measured binding energy spectra in the energy range of 14-60 eV are compared with the results of ADC(4) many-body Green`s function and also direct-Configuration Interaction (CI) and MRSD-CI calculations. The experimental orbital electron momentum profiles are compared with SCF theoretical profiles calculated using the target Hartree-Fock approximation with a range of basis sets and with Density Functional Theory predictions in the target Kohn-Sham approximation with non-local potentials. The truncated (aug-cc-pv5z) Dunning basis sets were used for the Density Functional Theory calculations which also include some treatment of correlation via the exchange and correlation potentials. Comparisons are also made with the full ion-neutral overlap amplitude calculated with MRSD-CI wave functions. Large, saturated basis sets (199-GTO) were employed for both the high level SCF near Hartree-Fock limit and MRSD-CI calculations to investigate the effects of electron correlation and relaxation. 66 refs., 9 tabs., 9 figs.

Orbital momentum profiles and binding energy spectra for the complete valence shell of molecular fluorine

International Nuclear Information System (INIS)

Zheng, Y.; Brion, C.E.; Brunger, M.J.; Zhao, K.; Grisogono, A.M.; Braidwood, S.; Weigold, E.; Chakravorty, S.J.; Davidson, E.R.; Sgamellotti, A.; von Niessen, W.

1996-01-01

The first electronic structural study of the complete valence shell binding energy spectrum of molecular fluorine, encompassing both the outer and inner valence regions, is reported. These binding energy spectra as well as the individual orbital momentum profiles have been measured using an energy dispersive multichannel electron momentum spectrometer at a total energy of 1500 eV, with an energy resolution of 1.5 eV and a momentum resolution of 0.1 a.u. The measured binding energy spectra in the energy range of 14-60 eV are compared with the results of ADC(4) many-body Green's function and also direct-Configuration Interaction (CI) and MRSD-CI calculations. The experimental orbital electron momentum profiles are compared with SCF theoretical profiles calculated using the target Hartree-Fock approximation with a range of basis sets and with Density Functional Theory predictions in the target Kohn-Sham approximation with non-local potentials. The truncated (aug-cc-pv5z) Dunning basis sets were used for the Density Functional Theory calculations which also include some treatment of correlation via the exchange and correlation potentials. Comparisons are also made with the full ion-neutral overlap amplitude calculated with MRSD-CI wave functions. Large, saturated basis sets (199-GTO) were employed for both the high level SCF near Hartree-Fock limit and MRSD-CI calculations to investigate the effects of electron correlation and relaxation. 66 refs., 9 tabs., 9 figs

Reference values for fluorine-18-fluorodeoxyglucose and fluorine-18-sodium fluoride uptake in human arteries

DEFF Research Database (Denmark)

Blomberg, Björn A; Thomassen, Anders; de Jong, Pim A

2017-01-01

OBJECTIVE: Reference values of fluorine-18-fluorodeoxyglucose (F-FDG) and fluorine-18-sodium fluoride (F-NaF) uptake in human arteries are unknown. The aim of this study was to determine age-specific and sex-specific reference values of arterial F-FDG and F-NaF uptake. PARTICIPANTS AND METHODS...

The control mechanism of surface traps on surface charge behavior in alumina-filled epoxy composites

International Nuclear Information System (INIS)

Li, Chuanyang; Hu, Jun; Lin, Chuanjie; He, Jinliang

2016-01-01

To investigate the role surface traps play in the charge injection and transfer behavior of alumina-filled epoxy composites, surface traps with different trap levels are introduced by different surface modification methods which include dielectric barrier discharges plasma, direct fluorination, and Cr 2 O 3 coating. The resulting surface physicochemical characteristics of experimental samples were observed using atomic force microscopy, scanning electron microscopy and fourier transform infrared spectroscopy. The surface potential under dc voltage was detected and the trap level distribution was measured. The results suggest that the surface morphology of the experimental samples differs dramatically after treatment with different surface modification methods. Different surface trap distributions directly determine the charge injection and transfer property along the surface. Shallow traps with trap level of 1.03–1.11 eV and 1.06–1.13 eV introduced by plasma and fluorination modifications are conducive for charge transport along the insulating surface, and the surface potential can be modified, producing a smoother potential curve. The Cr 2 O 3 coating can introduce a large number of deep traps with energy levels ranging from 1.09 to 1.15 eV. These can prevent charge injection through the reversed electric field formed by intensive trapped charges in the Cr 2 O 3 coatings. (paper)

Fluorinated Alq3 derivatives with tunable optical properties.

Science.gov (United States)

Shi, Yue-Wen; Shi, Min-Min; Huang, Jia-Chi; Chen, Hong-Zheng; Wang, Mang; Liu, Xiao-Dong; Ma, Yu-Guang; Xu, Hai; Yang, Bing

2006-05-14

This communication reports that not only the emission colour but also the photoluminescence quantum yield of Alq3 can be tuned by introducing fluorine atoms at different positions; with fluorination at C-5 the emission is red-shifted with a tremendously decreased intensity, fluorination at C-6 causes a blue-shift with a significantly increased intensity, and fluorination at C-7 has a minor effect on both the colour and intensity of Alq3's emission.

Surface properties of functional polymer systems

Science.gov (United States)

Wong, Derek

Polymer surface modification typically involves blending with other polymers or chemical modification of the parent polymer. Such strategies inevitably result in polymer systems that are spatially and chemically heterogeneous, and which exhibit the phenomenon of surface segregation. This work investigates the effects of chain architecture on the surface segregation behavior of such functionally modified polymers using a series of end- and center-fluorinated poly(D,L-lactide). Surface segregation of the fluorinated functional groups was observed in both chain architectures via AMPS and water contact angle. Higher surface segregation was noted for functional groups located at the chain end as opposed to those in the middle of the chain. A self-consistent mean-field lattice theory was used to model the composition depth profiles of functional groups and excellent agreement was found between the model predictions and the experimental AMPS data in both chain architectures. Polymer properties are also in general dependent on both time and temperature, and exhibit a range of relaxation times in response to environmental stimuli. This behavior arises from the characteristic frequencies of molecular motions of the polymer chain and the interrelationship between time and temperature has been widely established for polymer bulk properties. There is evidence that surface properties also respond in a manner that is time and temperature dependent and that this dependence may not be the same as that observed for bulk properties. AMPS and water contact angle experiments were used to investigate the surface reorganization behavior of functional groups using a series of anionically synthesized end-fluorinated and end-carboxylated poly(styrene). It was found that both types of functional end-groups reorganized upon a change in the polarity of the surface environment in order to minimize the surface free energy. ADXPS and contact angle results suggest that the reorganization depth was

Fluorine-18 nuclide and its PET imaging agent

International Nuclear Information System (INIS)

Wang Mingfang

2003-01-01

Fluorine-18 has predominant physical features with long half-life and the enough time for preparation of radiopharmaceuticals and PET imaging. Also, the chemical nature of fluorine-18 is similar to that of hydrogen, and the fluorine-18 labelled organic molecules can not change the non-labelled molecular character. Therefore, fluorine-18 is widely applied in the labelled glucose, amino acids, fatty acids, nucleotide, receptor-ligand and neurotransmitter molecular etc., with the propose of detecting the blood flow, metabolism, synthesis of the protein and the neurotransmitter function in brain by PET imaging. It is very important in the basic science and clinical research to understand and master the preparation of the fluorine-18 and its labelled compounds

Quantification of Fluorine Content in AFFF Concentrates

Science.gov (United States)

2017-09-29

for MilSpec compliance. Fluorocarbon surfactants are the most active components in these concentrates, and analysis of the fluorine content in the... physical requirements for AFFF concentrates includes a total fluorine content determination and a requirement for subsequent evaluations of this AFFF...the standard for fluorine content as well as the reference for chemical shift. For preparation of an NMR solution, it is important that the TFE

Determining concentration depth profiles in fluorinated networks by means of electric force microscopy

International Nuclear Information System (INIS)

Miccio, Luis A.; Kummali, Mohammed M.; Alegria, Angel; Montemartini, Pablo E.; Oyanguren, Patricia A.; Schwartz, Gustavo A.; Colmenero, Juan

2011-01-01

By means of electric force microscopy, composition depth profiles were measured with nanometric resolution for a series of fluorinated networks. By mapping the dielectric permittivity along a line going from the surface to the bulk, we were able to experimentally access to the fluorine concentration profile. Obtained data show composition gradient lengths ranging from 30 nm to 80 nm in the near surface area for samples containing from 0.5 to 5 wt. % F, respectively. In contrast, no gradients of concentration were detected in bulk. This method has several advantages over other techniques because it allows profiling directly on a sectional cut of the sample. By combining the obtained results with x-ray photoelectron spectroscopy measurements, we were also able to quantify F/C ratio as a function of depth with nanoscale resolution.

Do defects enhance fluorination of graphene?

Czech Academy of Sciences Publication Activity Database

da Costa, Sara; Ek Weis, Johan; Frank, Otakar; Fridrichová, Michaela; Bastl, Zdeněk; Kalbáč, Martin

2016-01-01

Roč. 6, AUG 2016 (2016), s. 81471-81476 ISSN 2046-2069 R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : fluorination * graphene * fluorine Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.108, year: 2016

[Fluorine as a factor in premature aging].

Science.gov (United States)

Machoy-Mokrzyńska, Anna

2004-01-01

osteoblasts, stimulate fibroblasts to produce collagenase, and trigger toxic reactions in osteocytes and chondrocytes of trabecular bone. Growing deformations of the skeleton reduce mobility and result in permanent crippling of the patient. Fluoride increases the mass of non-collagen proteins such as proteoglycans and glucosaminoglycans, accelerating skin aging even though protein biosynthesis is generally suppressed. The final outcome includes progressive vascular lesions and disorders of energy metabolism in muscles. In conclusions, the use of fluoride, particularly by dentists and pediatricians, must be controlled and adapted to individual needs. It is worth remembering that fluoride: is the cause of disability due to bone deformations and abnormalities in the musculoskeletal system; reduces the incidence of caries but do not protect against tooth loss; exerts an adverse effect of metabolic processes in the skin; accelerates calcification of vessels and thus reduces their elasticity; inhibits bioenergetic reactions, in particular oxidative phosphorylation, reducing physical activity of muscles. These findings suggest that fluorine may be yet another factor in accelerated aging and revive the dispute started more than two and half thousand years ago whether aging is a physiologic or pathologic process. The understanding of factors modifying the process of aging is the basis for preventive measures aimed at extending life and maintaining full psychosocial activity.

A facile method to prepare superhydrophobic fluorinated polysiloxane/ZnO nanocomposite coatings with corrosion resistance

Science.gov (United States)

Qing, Yongquan; Yang, Chuanning; Hu, Chuanbo; Zheng, Yansheng; Liu, Changsheng

2015-01-01

In this paper, we report a simple and inexpensive method for fabricating fluorinated polysiloxane/ZnO nanocomposite coatings on the steel substrates. The surface wettability and topology of coating were characterized by contact angle measurement, scanning electron microscope and Fourier transform infrared spectrometry. The results showed that the hydrophobic sbnd CH3 and sbnd CH2sbnd groups were introduced into ZnO particles via modification, the ZnO nanoparticles were modified from hydrophilic to hydrophobic. When the weight ratio of modified-ZnO to fluorinated polysiloxane was 13:7, the contact angle of nanocomposite coating was 166°, and a sliding angle of 4°, coating surface with hierarchical micro/nano-structures. In addition, the as-prepared superhydrophobic surface has excellent durability and corrosion resistance. It is believed that the facile and low-cost method offer an effective strategy and promising industrial applications for fabricating superhydrophobic surfaces on steel materials.

Electrochemical fluorination for processing of used nuclear fuel

Science.gov (United States)

Garcia-Diaz, Brenda L.; Martinez-Rodriguez, Michael J.; Gray, Joshua R.; Olson, Luke C.

2016-07-05

A galvanic cell and methods of using the galvanic cell is described for the recovery of uranium from used nuclear fuel according to an electrofluorination process. The galvanic cell requires no input energy and can utilize relatively benign gaseous fluorinating agents. Uranium can be recovered from used nuclear fuel in the form of gaseous uranium compound such as uranium hexafluoride, which can then be converted to metallic uranium or UO.sub.2 and processed according to known methodology to form a useful product, e.g., fuel pellets for use in a commercial energy production system.

Fluorine disposal processes for nuclear applications

International Nuclear Information System (INIS)

Netzer, W.D.

1977-01-01

A study was performed to determine the best method for disposing of waste fluorine in the effluent from a uranium oxide conversion facility. After reviewing the fluorine disposal literature and upon considering the nuclear safety constraints, it was determined that the two most promising processes were the fluidized alumina bed and the caustic scrubber. To obtain more design data for the latter process, a 3-stage, 5-in. I.D. spray tower was constructed and operated. This unit used a 10% potassium hydroxide solution at flows of 1.5 to 3 gpm and achieved a 90% fluorine efficiency at fluorine flowrates as high as 4 scfm. However, two toxic by-products, oxygen difluoride and nitroxy fluoride, were detected in the effluent gases. After considering the relative merits of both disposal processes, it is concluded that the fluidized bed is superior, especially if the contaminated waste material were salable

Fluorine disposal processes for nuclear applications

Energy Technology Data Exchange (ETDEWEB)

Netzer, W.D.

1977-04-08

A study was performed to determine the best method for disposing of waste fluorine in the effluent from a uranium oxide conversion facility. After reviewing the fluorine disposal literature and upon considering the nuclear safety constraints, it was determined that the two most promising processes were the fluidized alumina bed and the caustic scrubber. To obtain more design data for the latter process, a 3-stage, 5-in. I.D. spray tower was constructed and operated. This unit used a 10% potassium hydroxide solution at flows of 1.5 to 3 gpm and achieved a 90% fluorine efficiency at fluorine flowrates as high as 4 scfm. However, two toxic by-products, oxygen difluoride and nitroxy fluoride, were detected in the effluent gases. After considering the relative merits of both disposal processes, it is concluded that the fluidized bed is superior, especially if the contaminated waste material were salable.

Layer-dependent fluorination and doping of graphene via plasma treatment

International Nuclear Information System (INIS)

Chen Minjiang; Zhou Haiqing; Qiu Caiyu; Yang Huaichao; Yu Fang; Sun Lianfeng

2012-01-01

In this work, the fluorination of n-layer graphene is systematically investigated using CHF 3 and CF 4 plasma treatments. The G and 2D Raman peaks of graphene show upshifts after each of the two kinds of plasma treatment, indicating p-doping to the graphene. Meanwhile, D, D′ and D + G peaks can be clearly observed for monolayer graphene, whereas these peaks are weaker for thicker n-layer graphene (n ≥ 2) at the same experimental conditions. The upshifts of the G and 2D peaks and the ratio of I(2D)/I(G) for CF 4 plasma treated graphene are larger than those of CHF 3 plasma treated graphene. The ratio of I(D)/I(G) of the Raman spectra is notably small in CF 4 plasma treated graphene. These facts indicate that CF 4 plasma treatment introduces more p-doping and fewer defects for graphene. Moreover, the fluorination of monolayer graphene by CF 4 plasma treatment is reversible through thermal annealing while that by CHF 3 plasma treatment is irreversible. These studies explore the information on the surface properties of graphene and provide an optimal method of fluorinating graphene through plasma techniques. (paper)

Impact of fluorine based reactive chemistry on structure and properties of high moment magnetic material

Energy Technology Data Exchange (ETDEWEB)

Yang, Xiaoyu, E-mail: xiaoyu.yang@wdc.com; Chen, Lifan; Han, Hongmei; Fu, Lianfeng; Sun, Ming; Liu, Feng; Zhang, Jinqiu [Western Digital Corporation, 44100 Osgood Road, Fremont, California 94539 (United States)

2014-05-07

The impact of the fluorine-based reactive ion etch (RIE) process on the structural, electrical, and magnetic properties of NiFe and CoNiFe-plated materials was investigated. Several techniques, including X-ray fluorescence, 4-point-probe, BH looper, transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS), were utilized to characterize both bulk film properties such as thickness, average composition, Rs, ρ, Bs, Ms, and surface magnetic “dead” layers' properties such as thickness and element concentration. Experimental data showed that the majority of Rs and Bs changes of these bulk films were due to thickness reduction during exposure to the RIE process. ρ and Ms change after taking thickness reduction into account were negligible. The composition of the bulk films, which were not sensitive to surface magnetic dead layers with nano-meter scale, showed minimum change as well. It was found by TEM and EELS analysis that although both before and after RIE there were magnetic dead layers on the top surface of these materials, the thickness and element concentration of the layers were quite different. Prior to RIE, dead layer was actually native oxidation layers (about 2 nm thick), while after RIE dead layer consisted of two sub-layers that were about 6 nm thick in total. Sub-layer on the top was native oxidation layer, while the bottom layer was RIE “damaged” layer with very high fluorine concentration. Two in-situ RIE approaches were also proposed and tested to remove such damaged sub-layers.

A feasibility study for measuring fluorine in bone, in-vivo, using neutron activation analysis

International Nuclear Information System (INIS)

Chamberlain, M.; McNeill, F.; Aslam; Byun, S.H.

2008-01-01

Full text: Skeletal fluorosis is a bone disease which is a result of excessive fluoride ingestion and may cause osteosclerosis, osteoporosis and calcification of tendons and ligaments. Endemic levels of fluorosis are commonly reported in areas of the world with naturally high concentrations of fluoride in the drinking water. However, fluorosis is difficult to medically diagnose, and due to its prevalence, a non-invasive method for measuring the concentration of fluoride in bone is warranted. A feasibility study has been conducted to determine the possibility of measuring fluorine non-invasively in exposed populations using neutron activation analysis. Neutron activation analysis has been used successfully to measure the amount of fluoride in bone biopsy samples. However, measurement of fluorine is challenging, and has not, to our knowledge, previously been attempted in vivo, as the 20 F isotope has the very short half life of 11s. Transfer from activation counting must therefore be fast. For this study, plaster of Paris powder phantoms doped with varying fluoride concentrations were created to simulate a fist. They were irradiated using a low energy neutron beam at McMaster's Tandem Accelerator facility. The 7 Li(p,n) 7 Be reaction was used as the source of neutrons; the Be target was irradiated with an incident proton energy of 2.15MeV. The fluorine was detected via the neutron capture reaction, 19 F(n,γ) 20 F, using two 20 cm x 5 cm NaI detectors. Fluorine emits a gamma ray at 1633 keV upon decay. A calibration curve of peak area versus phantom fluorine content was created and a detection limit of 1.8 mg F/g Ca, with a corresponding dose of approximately 12 mSv to the hand. This data will be presented and the feasibility of measurement discussed in the context of the delivered dose. In addition, results of the investigation of the competing reaction, 23 Na(n,α) 20 F, will be presented. Data illustrating the relative activation and count rates from fluorine

Saturation of the hydroxyapatite mineral phase using radioactive fluorine; Saturacion de la fase mineral hidroxiapatita utilizando fluor radiactivo

Energy Technology Data Exchange (ETDEWEB)

Flores de la Torre, J.A.; Badillo A, V.E. [Universidad Autonoma de Zacatecas, 98000 Zacatecas (Mexico); Lopez D, F.A. [Unidad PET Ciclotron, Facultad de Medicina, UNAM, 04510 Mexico D.f. (Mexico)]. e-mail: ebadillo@cantera.reduaz.mx

2005-07-01

With the purpose of knowing the Anion exchange capacity (CIA) of the hydroxyapatite mineral phase, marketed by BIO-RAD, becomes necessary to saturate the surface of the mineral with an anion specie that possesses a strong affinity by this solid as it is the case of the fluorine. Moreover it takes advantage that offers the radioactive tracer technique, using the radioactive isotope of the fluorine, {sup 18}F, produced in the cyclotron of the UNAM. This saturation is obtained in terms of the quantity of retained fluorine (mmol/ 100 g) in the synthetic hydroxyapatite in function of the concentration of the solution of NaF that oscillates from 0.7 M up to 0.16 M to fixed values of pH of 9.2. Those results demonstrate that to this fixed pH value the saturation of the surface of the hydroxyapatite is achieved in approximately 30 mmol/ 100 g, using important concentrations of NaF that correspond to 0.14 M from now on. This result demonstrates the high capacity of the solid considered to retain considerable quantities of fluorine even to basic pH values. (Author)

Method for producing fluorinated diamond-like carbon films

Science.gov (United States)

Hakovirta, Marko J.; Nastasi, Michael A.; Lee, Deok-Hyung; He, Xiao-Ming

2003-06-03

Fluorinated, diamond-like carbon (F-DLC) films are produced by a pulsed, glow-discharge plasma immersion ion processing procedure. The pulsed, glow-discharge plasma was generated at a pressure of 1 Pa from an acetylene (C.sub.2 H.sub.2) and hexafluoroethane (C.sub.2 F.sub.6) gas mixture, and the fluorinated, diamond-like carbon films were deposited on silicon substrates. The film hardness and wear resistance were found to be strongly dependent on the fluorine content incorporated into the coatings. The hardness of the F-DLC films was found to decrease considerably when the fluorine content in the coatings reached about 20%. The contact angle of water on the F-DLC coatings was found to increase with increasing film fluorine content and to saturate at a level characteristic of polytetrafluoroethylene.

Fluorine and fluorine tolerance in fodder of domestic animals. Part 2. Pathophysiology of fluorine and fodder tests on domestic animals

Energy Technology Data Exchange (ETDEWEB)

Bronsch, K; Grieser, N

1964-01-01

Important tests with fluorine on domestic animals were critically evaluated with the aim of coming to some conclusion about fluorine tolerance in fodder for domestic animals, keeping various different factors in mind. Slightly lower concentrations were reached than those of the NRC in the USA, reckoning on a non-optimal mineral content, especially in calcium and phosphorus, since the USA obviously used a basis for feeding which was otherwise sufficient. According to these tests, fluoride is tolerated within certain limits by domestic animals without recognisable disadvantages. There are, however, important differences between different types of animals in regard to dosage.

Iodine and fluorine removal of the water using two synthetic adsorbents of great fixation capacity

International Nuclear Information System (INIS)

Neri G, M.; Badillo A, V. E.

2012-10-01

In this work is studied the affinity of two synthetic adsorbents of great fixation capacity, the alumina and the hydroxyapatite, as alternative for the removal of two halogens, iodine and fluorine of the water; the first of importance in the radioactive wastes management and the second of interest in public health. This study was carried out applying the technique of radioactive tracers, with 131 I and the radionuclide 18 F (it produced in the unit PET-cyclotron of the UNAM). The affinity of the synthetic adsorbents for the halogens is expressed in terms of the distribution coefficient and of the retention percent in function of the solution ph. The results obtained for the iodine and fluorine in the synthetic solids are markedly different; in the case of the iodine, the retention is worthless in the whole interval of studied ph while for the fluorine high distribution coefficient and fixation percentages are presented of until 100%. Also for the fluorine in hydroxyapatite high distribution coefficients and superiors are obtained in relation to those that are obtained in the alumina. In both solids the fluorine retention diminishes as the ph of the solution increases, what shows the competition with the hydroxyl ions for the active places in surface. (Author)

Advanced fluoride-based materials for energy conversion

CERN Document Server

Nakajima, Tsuyoshi

2015-01-01

Advanced Fluoride-Based Materials for Energy Conversion provides thorough and applied information on new fluorinated materials for chemical energy devices, exploring the electrochemical properties and behavior of fluorinated materials in lithium ion and sodium ion batteries, fluoropolymers in fuel cells, and fluorinated carbon in capacitors, while also exploring synthesis applications, and both safety and stability issues. As electronic devices, from cell phones to hybrid and electric vehicles, are increasingly common and prevalent in modern lives and require dependable, stable chemical energy devices with high-level functions are becoming increasingly important. As research and development in this area progresses rapidly, fluorine compounds play a critical role in this rapid progression. Fluorine, with its small size and the highest electronegativity, yields stable compounds under various conditions for utilization as electrodes, electrolytes, and membranes in energy devices. The book is an ideal reference f...

Production of uranium hexafluoride by fluorination tetra-fluoride with elemental fluorine under pressure; Proizvodnja uraovega heksafluorida s tlacnim fluoriranjem uranovega tetrafluorida z elementarnim fluorom

Energy Technology Data Exchange (ETDEWEB)

Lutar, K; Smalc, A; Zemljic, A [Institut Jozef Stefan, Ljubljana (Yugoslavia)

1984-07-01

In the introduction a brief description of some activities of fluorine chemistry department at the J. Stefan Institute is given - from production of elemental fluorine to the investigations in the field of uranium technology. Furthermore, a new method for the production of uranium hexafluoride is described more in detail. The method is based on the fluorination of uranium tetrafluoride with elemental fluorine. (author)

Effect of nanodiamond fluorination on the efficiency of quasispecular reflection of cold neutrons

Science.gov (United States)

Nesvizhevsky, V. V.; Dubois, M.; Gutfreund, Ph.; Lychagin, E. V.; Nezvanov, A. Yu.; Zhernenkov, K. N.

2018-02-01

Nanomaterials, which show large reflectivity for external radiation, are of general interest in science and technology. We report a result from our ongoing research on the reflection of low-energy neutrons from powders of detonation diamond nanoparticles. Our previous work showed a large probability for quasispecular reflection of neutrons from this medium. The model of neutron scattering from nanoparticles, which we have developed, suggests two ways to increase the quasispecular reflection probability: (1) the reduction of incoherent scattering by substitution of hydrogen with fluorine inside the nanoparticles, and (2) the sharpening of the neutron optical potential step by removal of amorphous s p2 carbon from the nanoparticle shells. We present experimental results on scattering of slow neutrons from both raw and fluorinated diamond nanoparticles with amorphous s p2 carbon removed by gas-solid fluorination. These results show a clear increase in quasispecular reflection probability.

Fluorine geochemistry in volcanic rock series

DEFF Research Database (Denmark)

Stecher, Ole

1998-01-01

A new analytical procedure has been established in order to determine low fluorine concentrations (30–100 ppm F) in igneous rocks, and the method has also proven successful for higher concentrations (100–4000 ppm F). Fluorine has been measured in a series of olivine tholeiites from the Reykjanes ...

Fluorinated Polyurethane Scaffolds for 19F Magnetic Resonance Imaging

NARCIS (Netherlands)

Lammers, Twan; Mertens, Marianne E.; Schuster, Philipp; Rahimi, Khosrow; Shi, Yang; Schulz, Volkmar; Kuehne, Alexander J.C.; Jockenhoevel, Stefan; Kiessling, Fabian

2017-01-01

Researchers used fluorinated polyurethane scaffolds for 19F magnetic resonance imaging. They generated a novel fluorinated polymer based on thermoplastic polyurethane (19F -TPU) which possesses distinct properties rendering it suitable for fluorine-based MRI. The 19F -TPU is synthesized from a

Bioreducible Fluorinated Peptide Dendrimers Capable of Circumventing Various Physiological Barriers for Highly Efficient and Safe Gene Delivery.

Science.gov (United States)

Cai, Xiaojun; Jin, Rongrong; Wang, Jiali; Yue, Dong; Jiang, Qian; Wu, Yao; Gu, Zhongwei

2016-03-09

Polymeric vectors have shown great promise in the development of safe and efficient gene delivery systems; however, only a few have been developed in clinical settings due to poor transport across multiple physiological barriers. To address this issue and promote clinical translocation of polymeric vectors, a new type of polymeric vector, bioreducible fluorinated peptide dendrimers (BFPDs), was designed and synthesized by reversible cross-linking of fluorinated low generation peptide dendrimers. Through masterly integration all of the features of reversible cross-linking, fluorination, and polyhedral oligomeric silsesquioxane (POSS) core-based peptide dendrimers, this novel vector exhibited lots of unique features, including (i) inactive surface to resist protein interactions; (ii) virus-mimicking surface topography to augment cellular uptake; (iii) fluorination-mediated efficient cellular uptake, endosome escape, cytoplasm trafficking, and nuclear entry, and (iv) disulfide-cleavage-mediated polyplex disassembly and DNA release that allows efficient DNA transcription. Noteworthy, all of these features are functionally important and can synergistically facilitate DNA transport from solution to the nucleus. As a consequences, BFPDs showed excellent gene transfection efficiency in several cell lines (∼95% in HEK293 cells) and superior biocompatibility compared with polyethylenimine (PEI). Meanwhile BFPDs provided excellent serum resistance in gene delivery. More importantly, BFPDs offer considerable in vivo gene transfection efficiency (in muscular tissues and in HepG2 tumor xenografts), which was approximately 77-fold higher than that of PEI in luciferase activity. These results suggest bioreducible fluorinated peptide dendrimers are a new class of highly efficient and safe gene delivery vectors and should be used in clinical settings.

Passivation of fluorinated activated charcoal

International Nuclear Information System (INIS)

Del Cul, G.D.; Trowbridge, L.D.; Simmons, D.W.; Williams, D.F.; Toth, L.M.

1997-10-01

The Molten Salt Reactor Experiment (MSRE), at the Oak Ridge National Laboratory has been shut down since 1969 when the fuel salt was drained from the core into two Hastelloy N tanks at the reactor site. In 1995, a multiyear project was launched to remediate the potentially hazardous conditions generated by the movement of fissile material and reactive gases from the storage tanks into the piping system and an auxiliary charcoal bed (ACB). The top 12 in. of the ACB is known by gamma scan and thermal analysis to contain about 2.6 kg U-233. According to the laboratory tests, a few feet of fluorinated charcoal are believed to extend beyond the uranium front. The remainder of the ACB should consist of unreacted charcoal. Fluorinated charcoal, when subjected to rapid heating, can decompose generating gaseous products. Under confined conditions, the sudden exothermic decomposition can produce high temperatures and pressures of near-explosive characteristics. Since it will be necessary to drill and tap the ACB to allow installation of piping and instrumentation for remediation and recovery activities, it is necessary to chemically convert the reactive fluorinated charcoal into a more stable material. Ammonia can be administered to the ACB as a volatile denaturing agent that results in the conversion of the C x F to carbon and ammonium fluoride, NH 4 F. The charcoal laden with NH 4 F can then be heated without risking any sudden decomposition. The only consequence of heating the treated material will be the volatilization of NH 4 F as a mixture of NH 3 and HF, which would primarily recombine as NH 4 F on surfaces below 200 C. The planned scheme for the ACB denaturing is to flow diluted ammonia gas in steps of increasing NH 3 concentration, 2% to 50%, followed by the injection of pure ammonia. This report summarizes the planned passivation treatment scheme to stabilize the ACB and remove the potential hazards. It also includes basic information, results of laboratory tests

Single and double stereoselective fluorination of (E-allylsilanes

Directory of Open Access Journals (Sweden)

Tredwell Matthew

2007-10-01

Full Text Available Abstract Acyclic allylic monofluorides were prepared by electrophilic fluorination of branched (E-allylsilanes with Selectfluor. These reactions proceeded with efficient transfer of chirality from the silylated to the fluorinated stereocentre. Upon double fluorination, an unsymmetrical ethyl syn-2,5-difluoroalk-3-enoic ester was prepared, the silyl group acting as an anti stereodirecting group for the two C-F bond forming events.

Preparation of Fluorine-Doped TiO2 Photocatalysts with Controlled Crystalline Structure

Directory of Open Access Journals (Sweden)

N. Todorova

2008-01-01

Full Text Available Nanocrystalline F-doped TiO2 powders were prepared by sol-gel route. The thermal behavior of the powders was recorded by DTA/TG technique. The crystalline phase of the fluorinated TiO2 powders was determined by X-ray diffraction technique. It was demonstrated that F-doping using CF3COOH favors the formation of rutile along with anatase phase even at low temperature. Moreover, the rutile's phase content increases with the increase of the quantity of the fluorine precursor in the starting solution. The surface area of the powders and the pore size distribution were studied by N2 adsorption-desorption using BET and BJH methods. X-ray photoelectron spectroscopy (XPS revealed that the fluorine is presented in the TiO2 powders mainly as metal fluoride in quantities ∼16 at %. The F-doped TiO2 showed a red-shift absorption in UV-vis region which was attributed to the increased content of rutile phase in the powders. The powders exhibited enhanced photocatalytic activity in decomposition of acetone.

Nuclear Magnetic Resonance Study of Fluorine-Graphite Intercalation Compounds

International Nuclear Information System (INIS)

Panich, A.M.; Goren, S.D.; Nakajima, T.; Vieth, H.-M.; Privalov, A.

1998-01-01

To study the origin of semimetal-metal and metal-insulator transformations, localization effects and C-E bonding in fluorine-intercalated graphite C x F, 13 C and 19 F NMR investigations have been carried out for a wide range of fluorine content, 3.8 8, are attributed to mobile fluorine acceptor species which are responsible for the increase of electric conductivity in the dilute compound. When increasing the fluorine content to x ∼ 8 corresponding to the maximum electric conductivity, covalent C-P bonds start to oc- cur. The number of these bonds grows with fluorine content resulting in the decrease in conductivity which is caused by a percolation mechanism rather than by a change in bond length. A difference in 19 F chemical shift for fluorine-intercalated graphite C x F and covalent graphite fluoride (CF) n has been observed and is attributed to different C-P bonding in these compounds

Fabrication of durable fluorine-free superhydrophobic polyethersulfone (PES) composite coating enhanced by assembled MMT-SiO2 nanoparticles

Science.gov (United States)

Zhang, Xiguang; Wang, Huaiyuan; Liu, Zhanjian; Zhu, Yixing; Wu, Shiqi; Wang, Chijia; Zhu, Yanji

2017-02-01

A durable fluorine-free polyethersulfone (PES) superhydrophobic composite coating with excellent wear-resistant and anti-corrosion properties has been successfully fabricated by combining sol-gel and spray technology. The robust micro/nano-structures of the prepared surface were established by introducing binary montmorillonite-silica (MMT-SiO2) assembled composite particles, which were formed by in-situ growth of SiO2 on MMT surfaces via sol-gel. Combined with the low surface energy of amino silicon oil (APDMS), the fluorine-free superhydrophoic PES coating was obtained with high water contact angle 156.1 ± 1.1° and low sliding angle 4.8 ± 0.7°. The anti-wear of the final PES/APDMS/MMT-SiO2 superhydrophobic coating can reach up to 60,100 cycles, which is outdistancing the pure PES coating (6800 cycles) and the PES/MMT/SiO2 coating prepared by simple physical mixture (18,200 cycles). The enhanced wear resistance property can be mainly attributed to the lubrication performance of APDMS and stable interface bonding force between the MMT surface and SiO2. Simultaneously, potentiodynamic polarization curves and electrochemical impedance spectroscopy exhibited the outstanding anti-corrosion property of PES/APDMS/MMT-SiO2 composite coating, with low corrosion current (1.6 × 10-10 A/cm2) and high protection efficiency (99.999%) even after 30 d immersion process. These test results show that this durable superhydrophobic PES composite coating can be hopefully to provide the possibility of industrial application.

Beam Simulation Studies of Plasma-Surface Interactions in Fluorocarbon Etching of Silicon and Silicon Dioxide

Science.gov (United States)

Gray, David C.

1992-01-01

A molecular beam apparatus has been constructed which allows the synthesis of dominant species fluxes to a wafer surface during fluorocarbon plasma etching. These species include atomic F as the primary etchant, CF _2 as a potential polymer forming precursor, and Ar^{+} or CF _{rm x}^{+} type ions. Ionic and neutral fluxes employed are within an order of magnitude of those typical of fluorocarbon plasmas and are well characterized through the use of in -situ probes. Etching yields and product distributions have been measured through the use of in-situ laser interferometry and line-of-sight mass spectrometry. XPS studies of etched surfaces were performed to assess surface chemical bonding states and average surface stoichiometry. A useful design guide was developed which allows optimal design of straight -tube molecular beam dosers in the collisionally-opaque regime. Ion-enhanced surface reaction kinetics have been studied as a function of the independently variable fluxes of free radicals and ions, as well as ion energy and substrate temperature. We have investigated the role of Ar ^{+} ions in enhancing the chemistries of F and CF_2 separately, and in combination on undoped silicon and silicon dioxide surfaces. We have employed both reactive and inert ions in the energy range most relevant to plasma etching processes, 20-500 eV, through the use of Kaufman and ECR type ion sources. The effect of increasing ion energy on the etching of fluorine saturated silicon and silicon dioxide surfaces was quantified through extensions of available low energy physical sputtering theory. Simple "site"-occupation models were developed for the quantification of the ion-enhanced fluorine etching kinetics in these systems. These models are suitable for use in topography evolution simulators (e.g. SAMPLE) for the predictive modeling of profile evolution in non-depositing fluorine-based plasmas such as NF_3 and SF_6. (Copies available exclusively from MIT Libraries, Rm. 14

Surface Energy and Setting Process of Contacting Surfaces

Directory of Open Access Journals (Sweden)

M. V. Musokhranov

2014-01-01

Full Text Available The paper deals with a challenge in terms of ensuring an accuracy of the relative position of the conjugated surfaces that is to determine a coefficient of friction. To solve it, there is a proposal to use the surface energy, as a tool that influences the contacting parts nature. Presently, energy of the surface layers at best is only stated, but not used in practice.Analysis of the conditions of interaction between two contacting surfaces, such as seizing and setting cannot be explained only from the position of the roughness parameters. It is found that these phenomena are explained by the appearing gripe (setting bridges, which result from the energy of interaction between two or more adjacent surfaces. The emerging phenomenon such as micro welding, i.e. occurring bonds, is caused by the overflow of energy, according to the theory of physics, from the surface with a high level of energy to the surface with the smaller one to balance the system as a whole.The paper shows that through the use of process, controlling the depth of the surface layer and creating a certain structure, the energy level of the material as a whole can be specified. And this will allow us to provide the necessary performance and mechanical properties. It means to create as many gripe bridges as possible to ensure continuous positioning i.e. a fixed connection of the contacting surfaces.It was determined that to increase a value of the friction coefficient, the physical and mechanical properties of the surface layer of the parts material must be taken into account, namely, in the part body accumulate the energy to be consumed for forming the surface.The paper gives recommendations for including the parts of the surface energy in the qualitative indicators of characteristics. This will make a technologist, when routing a process, to choose such operations and modes to provide the designer-specified parameters not only of the accuracy and surface finish, but also of the

The electrochemical fluorination of polymeric materials for high energy density aqueous and non-aqueous battery and fuel cell separators

Science.gov (United States)

Liu, C. C.

1983-01-01

A computerized system was established and the electrochemical fluorination of trichloroethylene, polyacrylic acid and polyvinyl alcohol in anhydrous hydrogen fluoride was attempted. Both solid substrates as well as membranes were used. Some difficulties were found in handling and analyzing the solid substrates and membranes. Further studies are needed in this area. A microprocessor aided electrochemical fluorination system capable of obtaining highly reproducible experimental results was established.

Fluorine in the solar neighborhood: Chemical evolution models

Science.gov (United States)

Spitoni, E.; Matteucci, F.; Jönsson, H.; Ryde, N.; Romano, D.

2018-04-01

Context. In light of new observational data related to fluorine abundances in solar neighborhood stars, we present chemical evolution models testing various fluorine nucleosynthesis prescriptions with the aim to best fit those new data. Aim. We consider chemical evolution models in the solar neighborhood testing various nucleosynthesis prescriptions for fluorine production with the aim of reproducing the observed abundance ratios [F/O] versus [O/H] and [F/Fe] versus [Fe/H]. We study in detail the effects of various stellar yields on fluorine production. Methods: We adopted two chemical evolution models: the classical two-infall model, which follows the chemical evolution of halo-thick disk and thin disk phases; and the one-infall model, which is designed only for thin disk evolution. We tested the effects on the predicted fluorine abundance ratios of various nucleosynthesis yield sources, that is, asymptotic giant branch (AGB) stars, Wolf-Rayet (W-R) stars, Type II and Type Ia supernovae, and novae. Results: The fluorine production is dominated by AGB stars but the W-R stars are required to reproduce the trend of the observed data in the solar neighborhood with our chemical evolution models. In particular, the best model both for the two-infall and one-infall cases requires an increase by a factor of 2 of the W-R yields. We also show that the novae, even if their yields are still uncertain, could help to better reproduce the secondary behavior of F in the [F/O] versus [O/H] relation. Conclusions: The inclusion of the fluorine production by W-R stars seems to be essential to reproduce the new observed ratio [F/O] versus [O/H] in the solar neighborhood. Moreover, the inclusion of novae helps to reproduce the observed fluorine secondary behavior substantially.

Fluorine-fixing efficiency on calcium-based briquette: pilot experiment, demonstration and promotion.

Science.gov (United States)

Yang, Jiao-lan; Chen, Dong-qing; Li, Shu-min; Yue, Yin-ling; Jin, Xin; Zhao, Bing-cheng; Ying, Bo

2010-02-05

The fluorosis derived from coal burning is a very serious problem in China. By using fluorine-fixing technology during coal burning we are able to reduce the release of fluorides in coal at the source in order to reduce pollution to the surrounding environment by coal burning pollutants as well as decrease the intake and accumulating amounts of fluorine in the human body. The aim of this study was to conduct a pilot experiment on calcium-based fluorine-fixing material efficiency during coal burning to demonstrate and promote the technology based on laboratory research. A proper amount of calcium-based fluorine sorbent was added into high-fluorine coal to form briquettes so that the fluorine in high-fluorine coal can be fixed in coal slag and its release into atmosphere reduced. We determined figures on various components in briquettes and fluorine in coal slag as well as the concentrations of indoor air pollutants, including fluoride, sulfur dioxide and respirable particulate matter (RPM), and evaluated the fluorine-fixing efficiency of calcium-based fluorine sorbents and the levels of indoor air pollutants. Pilot experiments on fluorine-fixing efficiency during coal burning as well as its demonstration and promotion were carried out separately in Guiding and Longli Counties of Guizhou Province, two areas with coal burning fluorosis problems. If the calcium-based fluorine sorbent mixed coal was made into honeycomb briquettes the average fluorine-fixing ratio in the pilot experiment was 71.8%. If the burning calcium-based fluorine-fixing bitumite was made into a coalball, the average of fluorine-fixing ratio was 77.3%. The concentration of fluoride, sulfur dioxide and PM10 of indoor air were decreased significantly. There was a 10% increase in the cost of briquettes due to the addition of calcium-based fluorine sorbent. The preparation process of calcium-based fluorine-fixing briquette is simple yet highly flammable and it is applicable to regions with abundant

Investigations to increase the efficiency of fluorine and boron removal from groundwater using radiation-induced graft polymerization adsorbent

International Nuclear Information System (INIS)

Iyatomi, Yosuke; Shimada, Akiomi; Ogata, Nobuhisa; Sugihara, Kozo; Hoshina, Hiroyuki; Seko, Noriaki; Kasai, Noboru; Ueki, Yuji; Tamada, Masao

2010-01-01

The Japan Atomic Energy Agency is performing a research project in the Mizunami Underground Research Laboratory (MIU) to build a firm scientific and technological basis for the studies of the deep underground environment in crystalline rock. In the project, it is necessary to reduce the fluorine and boron concentrations in groundwater pumped from the MIU shafts to levels below the environmental standards. This is done at the MIU water treatment facility using coagulation and ion exchange treatment for fluorine and boron, respectively. In addition, in 2006, research started on the efficient treatment of groundwater for removal of fluorine and boron using a radiation-induced graft polymerization adsorbent. The adsorbent removed boron at a flow rate (space velocity (SV)=120 h -1 ) higher than that of a general ion exchange resin (SV=10 h -1 ) and the adsorbent could be used repeatedly. It was also apparent that the pH of groundwater had an influence on adsorption performance. With respect to fluorine removal, more than 90% of fluorine was removed. However, the adsorbent for fluorine showed a lower adsorption capacity than that for boron. The reason for this difference is considered to be related to the initial concentration difference between fluorine and boron in the groundwater. Therefore, it is necessary to define the initial concentrations of dissolved materials, which can be used as better indicators of the performance of the adsorbent. (author)

Comparison of topotactic fluorination methods for complex oxide films

Science.gov (United States)

Moon, E. J.; Choquette, A. K.; Huon, A.; Kulesa, S. Z.; Barbash, D.; May, S. J.

2015-06-01

We have investigated the synthesis of SrFeO3-αFγ (α and γ ≤ 1) perovskite films using topotactic fluorination reactions utilizing poly(vinylidene fluoride) as a fluorine source. Two different fluorination methods, a spin-coating and a vapor transport approach, were performed on as-grown SrFeO2.5 films. We highlight differences in the structural, compositional, and optical properties of the oxyfluoride films obtained via the two methods, providing insight into how fluorination reactions can be used to modify electronic and optical behavior in complex oxide heterostructures.

Plasma fluorination of vertically aligned carbon nanotubes: functionalization and thermal stability.

Science.gov (United States)

Struzzi, Claudia; Scardamaglia, Mattia; Hemberg, Axel; Petaccia, Luca; Colomer, Jean-François; Snyders, Rony; Bittencourt, Carla

2015-01-01

Grafting of fluorine species on carbon nanostructures has attracted interest due to the effective modification of physical and chemical properties of the starting materials. Various techniques have been employed to achieve a controlled fluorination yield; however, the effect of contaminants is rarely discussed, although they are often present. In the present work, the fluorination of vertically aligned multiwalled carbon nanotubes was performed using plasma treatment in a magnetron sputtering chamber with fluorine diluted in an argon atmosphere with an Ar/F2 ratio of 95:5. The effect of heavily diluted fluorine in the precursor gas mixture is investigated by evaluating the modifications in the nanotube structure and the electronic properties upon plasma treatment. The existence of oxygen-based grafted species is associated with background oxygen species present in the plasma chamber in addition to fluorine. The thermal stability and desorption process of the fluorine species grafted on the carbon nanotubes during the fluorine plasma treatment were evaluated by combining different spectroscopic techniques.

Plasma fluorination of vertically aligned carbon nanotubes: functionalization and thermal stability

Directory of Open Access Journals (Sweden)

Claudia Struzzi

2015-12-01

Full Text Available Grafting of fluorine species on carbon nanostructures has attracted interest due to the effective modification of physical and chemical properties of the starting materials. Various techniques have been employed to achieve a controlled fluorination yield; however, the effect of contaminants is rarely discussed, although they are often present. In the present work, the fluorination of vertically aligned multiwalled carbon nanotubes was performed using plasma treatment in a magnetron sputtering chamber with fluorine diluted in an argon atmosphere with an Ar/F2 ratio of 95:5. The effect of heavily diluted fluorine in the precursor gas mixture is investigated by evaluating the modifications in the nanotube structure and the electronic properties upon plasma treatment. The existence of oxygen-based grafted species is associated with background oxygen species present in the plasma chamber in addition to fluorine. The thermal stability and desorption process of the fluorine species grafted on the carbon nanotubes during the fluorine plasma treatment were evaluated by combining different spectroscopic techniques.

FLUORINE IN THE SOLAR NEIGHBORHOOD: NO EVIDENCE FOR THE NEUTRINO PROCESS

International Nuclear Information System (INIS)

Jönsson, H.; Ryde, N.; Spitoni, E.; Matteucci, F.; Cunha, K.; Smith, V.; Hinkle, K.; Schultheis, M.

2017-01-01

Asymptotic giant branch (AGB) stars are known to produce “cosmic” fluorine, but it is uncertain whether these stars are the main producers of fluorine in the solar neighborhood or if any of the other proposed formation sites, Type II supernovae (SNe II) and/or Wolf-Rayet (W-R) stars, are more important. Recent articles have proposed both AGB stars and SNe II as the dominant sources of fluorine in the solar neighborhood. In this paper we set out to determine the fluorine abundance in a sample of 49 nearby, bright K giants for which we previously have determined the stellar parameters, as well as alpha abundances homogeneously from optical high-resolution spectra. The fluorine abundance is determined from a 2.3 μ m HF molecular line observed with the spectrometer Phoenix. We compare the fluorine abundances with those of alpha-elements mainly produced in SNe II and find that fluorine and the alpha-elements do not evolve in lockstep, ruling out SNe II as the dominating producers of fluorine in the solar neighborhood. Furthermore, we find a secondary behavior of fluorine with respect to oxygen, which is another evidence against the SNe II playing a large role in the production of fluorine in the solar neighborhood. This secondary behavior of fluorine will put new constraints on stellar models of the other two suggested production sites: AGB stars and W-R stars.

FLUORINE IN THE SOLAR NEIGHBORHOOD: NO EVIDENCE FOR THE NEUTRINO PROCESS

Energy Technology Data Exchange (ETDEWEB)

Jönsson, H.; Ryde, N. [Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-22100 Lund (Sweden); Spitoni, E.; Matteucci, F. [Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, via G.B. Tiepolo 11, I-34131, Trieste (Italy); Cunha, K. [Observatório Nacional, Rua General José Cristino, 77, 20921-400 São Cristóvão, Rio de Janeiro, RJ (Brazil); Smith, V.; Hinkle, K. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Schultheis, M., E-mail: henrikj@astro.lu.se [Observatoire de la Cote d’Azur, Boulevard de l’Observatoire, B.P. 4229, F-06304 NICE Cedex 4 (France)

2017-01-20

Asymptotic giant branch (AGB) stars are known to produce “cosmic” fluorine, but it is uncertain whether these stars are the main producers of fluorine in the solar neighborhood or if any of the other proposed formation sites, Type II supernovae (SNe II) and/or Wolf-Rayet (W-R) stars, are more important. Recent articles have proposed both AGB stars and SNe II as the dominant sources of fluorine in the solar neighborhood. In this paper we set out to determine the fluorine abundance in a sample of 49 nearby, bright K giants for which we previously have determined the stellar parameters, as well as alpha abundances homogeneously from optical high-resolution spectra. The fluorine abundance is determined from a 2.3 μ m HF molecular line observed with the spectrometer Phoenix. We compare the fluorine abundances with those of alpha-elements mainly produced in SNe II and find that fluorine and the alpha-elements do not evolve in lockstep, ruling out SNe II as the dominating producers of fluorine in the solar neighborhood. Furthermore, we find a secondary behavior of fluorine with respect to oxygen, which is another evidence against the SNe II playing a large role in the production of fluorine in the solar neighborhood. This secondary behavior of fluorine will put new constraints on stellar models of the other two suggested production sites: AGB stars and W-R stars.

Diffusion phenomena of fluorine and cations in molten Li2BeF4, LiBeF3 and NaBeF3

International Nuclear Information System (INIS)

Ohno, Hideo

1984-03-01

Self-diffusion coefficients of fluorine and cations in molten LiF-BeF 2 and NaF-BeF 2 systems were summarized by the capillary reservoir technique. The diffusion coefficients and the activation energies of cations in these molten salts follow a similar behavior with those of cations in molten alkali halides. On the other hand, self-diffusion of fluorine have unusually high diffusion coefficients and activation energies. The characteristic diffusion phenomena of fluorine in these molten alkali fluoroberyllates are very similar to those of oxygen in molten CaO-SiO 2 and CaO-SiO 2 -Al 2 O 3 slag. The dynamical behavior of Li and F in molten Li 2 BeF 4 was also analyzed by NMR technique. According to both these experiments, most probable mechanism of characteristic diffusion of fluorine in these molten systems could be dissociation of F atom from complex anion and long distance diffusion. (author)

In vivo quantification of bone-fluorine by delayed neutron activation analysis: a pilot study of hand-bone-fluorine levels in a Canadian population

International Nuclear Information System (INIS)

Chamberlain, Mike; Gräfe, James L; Aslam; Byun, Soo-Hyun; Chettle, David R; Egden, Lesley M; Webber, Colin E; McNeill, Fiona E

2012-01-01

Humans can be exposed to fluorine (F) through their diet, occupation, environment and oral dental care products. Fluorine, at proper dosages, is believed to have positive effects by reducing the incidence of dental caries, but fluorine toxicity can occur when people are exposed to excessive quantities of fluorine. In this paper we present the results of a small pilot in vivo study on 33 participants living in Southwestern Ontario, Canada. The mean age of participants was 45 ± 18 years with a range of 20–87 years. The observed calcium normalized hand-bone-fluorine concentrations in this small pilot study ranged from 1.1 to 8.8 mg F/g Ca. Every person measured in this study had levels of fluorine in bone above the detection limit of the system. The average fluorine concentration in bone was found to be 3.5 ± 0.4 mg F/g Ca. No difference was observed in average concentration for men and women. In addition, a significant correlation (r 2 = 0.55, p < 0.001) was observed between hand-bone-fluorine content and age. The amount of fluorine was found to increase at a rate of 0.084 ± 0.014 mg F/g Ca per year. There was no significant difference observed in this small group of subjects between the accumulation rates in men and women. To the best of our knowledge, this is the first time data from in vivo measurement of fluorine content in humans by neutron activation analysis have been presented. The data determined by this technique were found to be consistent with results from ex vivo studies from other countries. We suggest that the data demonstrate that this low risk non-invasive diagnostic technique will permit the routine assessment of bone-fluorine content with potential application in the study of clinical bone-related diseases. This small study demonstrated that people in Southern Ontario are exposed to fluoride in measureable quantities, and that fluoride can be seen to accumulate in bone with age. However, all volunteers were found to have levels below those

In vivo quantification of bone-fluorine by delayed neutron activation analysis: a pilot study of hand-bone-fluorine levels in a Canadian population.

Science.gov (United States)

Chamberlain, Mike; Gräfe, James L; Aslam; Byun, Soo-Hyun; Chettle, David R; Egden, Lesley M; Webber, Colin E; McNeill, Fiona E

2012-03-01

Humans can be exposed to fluorine (F) through their diet, occupation, environment and oral dental care products. Fluorine, at proper dosages, is believed to have positive effects by reducing the incidence of dental caries, but fluorine toxicity can occur when people are exposed to excessive quantities of fluorine. In this paper we present the results of a small pilot in vivo study on 33 participants living in Southwestern Ontario, Canada. The mean age of participants was 45 ± 18 years with a range of 20-87 years. The observed calcium normalized hand-bone-fluorine concentrations in this small pilot study ranged from 1.1 to 8.8 mg F/g Ca. Every person measured in this study had levels of fluorine in bone above the detection limit of the system. The average fluorine concentration in bone was found to be 3.5 ± 0.4 mg F/g Ca. No difference was observed in average concentration for men and women. In addition, a significant correlation (r(2) = 0.55, p fluorine content and age. The amount of fluorine was found to increase at a rate of 0.084 ± 0.014 mg F/g Ca per year. There was no significant difference observed in this small group of subjects between the accumulation rates in men and women. To the best of our knowledge, this is the first time data from in vivo measurement of fluorine content in humans by neutron activation analysis have been presented. The data determined by this technique were found to be consistent with results from ex vivo studies from other countries. We suggest that the data demonstrate that this low risk non-invasive diagnostic technique will permit the routine assessment of bone-fluorine content with potential application in the study of clinical bone-related diseases. This small study demonstrated that people in Southern Ontario are exposed to fluoride in measureable quantities, and that fluoride can be seen to accumulate in bone with age. However, all volunteers were found to have levels below those expected with clinical fluorosis, and only

Sample preparation and study by electronic diffraction of oxidations and fluorinations of some metals and alloys

International Nuclear Information System (INIS)

Auguin, B.

1963-06-01

After having recalled that electron diffraction is particularly adapted to the study of thin films and surface layers, notably those forming during corrosions, and recalled some characteristics of this technique (wavelength, interactions with substances, parasite reactions, observation by transmission or reflection, obtained diagrams for polycrystalline and mono-crystalline substances), the author describes how samples are prepared in the case of examinations performed by transmission and by reflection. As fluorination agents are used for the separation of uranium 235 and 238, the second part discusses some works related to the fluorination of metals and alloys, some of them being used in these separation installations. Chlorine trifluoride is generally used and materials are generally oxidised. Thus, the author reports the study of the action of ClF 3 on different oxides. Oxidations of iron, nickel and Monel are addressed, as well as the behaviour of stainless steel. The study of fluorinations of metals (nickel, chromium, copper), alloys (stainless steel, Monel) and oxides is reported. The author finally addresses treatments performed after fluorinations: vacuum heating, action of humid air

The fluorine destruction in stars: First experimental study of the 19F(p,α)16O reaction at astrophysical energies

International Nuclear Information System (INIS)

La Cognata, M.; Mukhamedzhanov, A.; Spitaleri, C.; Indelicato, I.; Aliotta, M.; Burjan, V.; Cherubini, S.; Coc, A.; Gulino, M.; Hons, Z.; Kiss, G. G.; Kroha, V.; Lamia, L.; Mrazek, J.; Palmerini, S.; Piskor, S.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.

2012-01-01

The 19 F(p,α) 16 O reaction is an important fluorine destruction channel in the proton-rich outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogendeficient post-AGB star nucleosynthesis. So far, available direct measurements do not reach the energy region of astrophysical interest (E cm ∼ 300 keV), because of the hindrance effect of the Coulomb barrier. The Trojan Horse (TH) method was thus used to access this energy region, by extracting the quasi-free contribution to the 2 H( 19 F,α 16 O)n reaction. The TH measurement of the α 0 channel, which is the dominant one at such energies, shows the presence of resonant structures not observed before that cause an increase of the reaction rate at astrophysical temperatures up to a factor of 1.7, with potential important consequences for stellar nucleosynthesis.

Synthesis of a fluorine-18 labeled hypoxic cell sensitizer

International Nuclear Information System (INIS)

Jerabek, P.A.; Dischino, D.D.; Kilbourn, M.R.; Welch, M.J.

1984-01-01

The objective of this work was to synthesize a positron emitting radiosensitizing agent as a potential in vivo marker of hypoxic regions within tumors, and ischemic areas of the heart and brain. The method involved radiochemical synthesis of fluorine-18 labeled 1-(2-nitro-imidazolyl)-3-fluoro-2-propanol via nucleophilic ring opening of 1-(2,3-epoxypropyl)2-nitro-imidzole by fluorine-18 labeled tetrabutylammonium fluoride (TBAF). Fluroine-18 TBAF was prepared by the exchange reaction of TBAF with aqueous flourine-18 produced by proton bombardment of enriched oxygen-18 water. The aqueous solution was evaporated carefully by azeotropic distillation with acetonitrile. The fluorine-18 labeled TBAF was taken up in N,N-dimethylacetamide or dimethysulfoxide, then reacted with the episode at 60C for 30 minutes. Separation and identification of the fluorine-18 labeled products by high performance liquid chromatography showed a radioactive peak with a retention time identical to that of 1-(2-nitro-1-imidazolyl)-3-fluoro-2-propanol and a second radioactive peak with a retention time three minutes longer in addition to unreacted fluorine-18 labeled TBAF. The second radioactive peak may represent fluorine-18 labeled 1-2-nitro-1-imidazolyl)-2-fluoro-3-propanol. The average radiochemical yield from reactions run in N,N-dimethylacetamide using 20 micromoles of TBAF and 1-2 mg of the epoxide was l7% in a synthesis time of about 40 minutes. The synthesis of fluorohydrins by the reaction of fluorine-18 labeled TBAF on epoxides represents a new method for the preparation of fluorine-18 labeled fluorohydrins

Production of fluorine-18 from eithium carbonate in a research reactor

International Nuclear Information System (INIS)

Gasiglia, H.T.

1978-01-01

A method for the production of fluorine-18 in a research reactor, from irradiated lithium carbonate, is described. Fluorine-18 is separated from impurities in a alumina column, which is an appropriate procedure for its production as a carrier-free radioisotope for oral administration. Characteristics of the product, when fluorine is separated from irradiated target in an usual alumina column, are compared with those when fluorine is separated in a previously calcined(1000 0 C) alumina column: Yields of chemical separation and chemical forms of radioisotope obtained are studied. Fluorine elution is investigated for several eluant concentrations and the use of a lower concentrated eluant is emphasized. Purity degree of fluorine-18 solutions separated. A routine production procedure is determined by irradiating enriched lithium carbonate (95% 6 Li). Theoretical yields are compared with fluorine-18 production yields obtained in several irradiations [pt

Comparison of topotactic fluorination methods for complex oxide films

Energy Technology Data Exchange (ETDEWEB)

Moon, E. J., E-mail: em582@drexel.edu; Choquette, A. K.; Huon, A.; Kulesa, S. Z.; May, S. J., E-mail: smay@coe.drexel.edu [Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Barbash, D. [Centralized Research Facilities, Drexel University, Philadelphia, Pennsylvania 19104 (United States)

2015-06-01

We have investigated the synthesis of SrFeO{sub 3−α}F{sub γ} (α and γ ≤ 1) perovskite films using topotactic fluorination reactions utilizing poly(vinylidene fluoride) as a fluorine source. Two different fluorination methods, a spin-coating and a vapor transport approach, were performed on as-grown SrFeO{sub 2.5} films. We highlight differences in the structural, compositional, and optical properties of the oxyfluoride films obtained via the two methods, providing insight into how fluorination reactions can be used to modify electronic and optical behavior in complex oxide heterostructures.

Comparison of topotactic fluorination methods for complex oxide films

Directory of Open Access Journals (Sweden)

E. J. Moon

2015-06-01

Full Text Available We have investigated the synthesis of SrFeO3−αFγ (α and γ ≤ 1 perovskite films using topotactic fluorination reactions utilizing poly(vinylidene fluoride as a fluorine source. Two different fluorination methods, a spin-coating and a vapor transport approach, were performed on as-grown SrFeO2.5 films. We highlight differences in the structural, compositional, and optical properties of the oxyfluoride films obtained via the two methods, providing insight into how fluorination reactions can be used to modify electronic and optical behavior in complex oxide heterostructures.

Synthesis of fluorinated poly(arylene ether)s with dibenzodioxin and spirobisindane units from new bis(pentafluorophenyl)- and bis(nonafluorobiphenyl)-containing monomers

DEFF Research Database (Denmark)

Tkachenko, Ihor M.; Belov, Nikolay A.; Kobzar, Yaroslav L.

2017-01-01

(nonafluorophenyl)-containing monomers have higher average molecular masses (Mw) in the range 47,000–88,300 and are able to form robust, solvent-cast films. Good thermal stabilities in air (up to 350 °C) were observed in all fluorinated polymers. The Brunauer–Emmett–Teller specific surface area and the pore size of polymers can...... be controlled by varying the type of the initial fluorinated monomers. It was shown that introduction of perfluorobiphenyl units is an effective tool for increasing the surface area up to 156.8 m2 g−1....

Fluorinated Compounds in US Fast Food Packaging | Science ...

Science.gov (United States)

Per- and polyfluoroalkyl substances (PFASs) are highly persistent synthetic chemicals, some of which have been associated with cancer, developmental toxicity, immunotoxicity, and other health effects. PFASs in grease-resistant food packaging can leach into food and increase dietary exposure. We collected ∼400 samples of food contact papers, paperboard containers, and beverage containers from fast food restaurants throughout the United States and measured total fluorine using particle-induced γ-ray emission (PIGE) spectroscopy. PIGE can rapidly and inexpensively measure total fluorine in solid-phase samples. We found that 46% of food contact papers and 20% of paperboard samples contained detectable fluorine (>16 nmol/cm2). Liquid chromatography/high-resolution mass spectrometry analysis of a subset of 20 samples found perfluorocarboxylates, perfluorosulfonates, and other known PFASs and/or unidentified polyfluorinated compounds (based on nontargeted analysis). The total peak area for PFASs was higher in 70% of samples (10 of 14) with a total fluorine level of >200 nmol/cm2 compared to six samples with a total fluorine level of food packaging demonstrates their potentially significant contribution to dietary PFAS exposure and envi

Plasma deposited fluorinated films on porous membranes

Energy Technology Data Exchange (ETDEWEB)

Gancarz, Irena [Department of Polymer and Carbon Materials, Wrocław University of Technology, 50-370 Wrocław (Poland); Bryjak, Marek, E-mail: marek.bryjak@pwr.edu.pl [Department of Polymer and Carbon Materials, Wrocław University of Technology, 50-370 Wrocław (Poland); Kujawski, Jan; Wolska, Joanna [Department of Polymer and Carbon Materials, Wrocław University of Technology, 50-370 Wrocław (Poland); Kujawa, Joanna; Kujawski, Wojciech [Nicolaus Copernicus University, Faculty of Chemistry, 7 Gagarina St., 87-100 Torun (Poland)

2015-02-01

75 KHz plasma was used to modify track etched poly(ethylene terephthalate) membranes and deposit on them flouropolymers. Two fluorine bearing monomers were used: perflourohexane and hexafluorobenzene. The modified surfaces were analyzed by means of attenuated total reflection infra-red spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and wettability. It was detected that hexaflourobenxene deposited to the larger extent than perflourohaxane did. The roughness of surfaces decreased when more fluoropolymer was deposited. The hydrophobic character of surface slightly disappeared during 20-days storage of hexaflourobenzene modified membrane. Perfluorohexane modified membrane did not change its character within 120 days after modification. It was expected that this phenomenon resulted from post-reactions of oxygen with radicals in polymer deposits. The obtained membranes could be used for membrane distillation of juices. - Highlights: • Plasma deposited hydrophobic layer of flouropolymers. • Deposition degree affects the surface properties. • Hydrohilization of surface due to reaction of oxygen with entrapped radicals. • Possibility to use modified porous membrane for water distillation and apple juice concentration.

Structures and properties of fluorinated amorphous carbon films

Science.gov (United States)

Huang, K. P.; Lin, P.; Shih, H. C.

2004-07-01

Fluorinated amorphous carbon (a-C:F) films were deposited by radio frequency bias assisted microwave plasma electron cyclotron resonance chemical vapor deposition with tetrafluoromethane (CF4) and acetylene (C2H2) as precursors. The deposition process was performed at two flow ratios R=0.90 and R=0.97, where R=CF4/(CF4+C2H2). The samples were annealed at 300 °C for 30 min. in a N2 atmosphere. Both Fourier transform infrared and electron spectroscopy for chemical analyzer were used to characterize the a-C:F film chemical bond and fluorine concentration, respectively. A high resolution electron energy loss spectrometer was applied to detect the electronic structure. The higher CF4 flow ratio (R=0.97) produced more sp3 linear structure, and it made the a-C:F film smoother and softer. A lifetime of around 0.34 μs and an energy gap of ˜2.75 eV were observed in both the as-deposited and after annealing conditions. The short carriers lifetime in the a-C:F film made the photoluminescence peak blueshift. The annealing changed both the structure and composition of the a-C:F film. The type of fluorocarbon bond and electronic structure characterized the mechanical and physical properties of a-C:F film.

Novel Synthesis of Slightly Fluorinated Graphene Quantum Dots with Luminescent and Paramagnetic Properties through Thermal Cutting of Fluorinated Graphene

Science.gov (United States)

Feng, Qian; Xiao, Wenqing; Zheng, Yongping; Lin, Yuda; Li, Jiaxin; Ye, Qingying; Huang, Zhigao

2018-01-01

A novel approach has been developed to synthesize slightly fluorinated graphene quantum dots (GQDs-F) through thermal cutting of highly fluorinated graphene. The fluorinated graphene with substantial structure defects is fragile and is readily attacked. The direct evaporation of abundant CFn (n = 2, 3) groups near structure defects lead to the loss of adjacent skelton C atoms, and the fluorinated graphene can be thermally cut into GQDs-F with a relatively uniform nanosize in pyrolysis at 810 K. The GQDs-F with a low F/C atomic ratio of ca. 0.03 exhibit excitation wavelength-dependent properties with multicolor photoluminescence (PL) from blue to green. At the same time, F adatoms that are most likely located at the edges of GQDs-F have a high efficiency of introducing paramagnetic centres, and GQDs-F show a strong paramagnetism because of sp3-type defects and magnetic zigzag edges. The graphene quantum dots with such multimodal capabilities should have great applied value in material science. PMID:29316730

Fluorine 18 in tritium generator ceramic materials

International Nuclear Information System (INIS)

Jimenez-Becerril, J.; Bosch, P.; Bulbulian, S.

1992-01-01

At present time, the ceramic materials generators of tritium are very interesting mainly by the necessity of to found an adequate product for its application as fusion reactor shielding. The important element that must contain the ceramic material is the lithium and especially the isotope with mass=6. The tritium in these materials is generated by neutron irradiation, however, when the ceramic material contains oxygen, then is generated too fluorine 18 by the action of energetic atoms of tritium in recoil on the 16 O, as it is showed in the next reactions: 1) 6 Li (n, α) 3 H ; 2) 16 O( 3 H, n) 18 F . In the present work was studied the LiAlO 2 and the Li 2 O. The first was prepared in the laboratory and the second was used such as it is commercially expended. In particular the interest of this work is to study the chemical behavior of fluorine-18, since if it would be mixed with tritium it could be contaminate the fusion reactor fuel. The ceramic materials were irradiated with neutrons and also the chemical form of fluorine-18 produced was studied. It was determined the amount of fluorine-18 liberated by the irradiated materials when they were submitted to extraction with helium currents and argon-hydrogen mixtures and also it was investigated the possibility about the fluorine-18 was volatilized then it was mixed so with the tritium. Finally it was founded that the liberated amount of fluorine-18 depends widely of the experimental conditions, such as the temperature and the hydrogen amount in the mixture of dragging gas. (Author)

Production of elemental fluorine at IPEN - S. Paulo, Brazil

International Nuclear Information System (INIS)

Abrao, A.; Ikuta, A.; Wirkner, F.M.; Silva, F.P. da.

1981-04-01

The construction, installation and operation of a pilot unit for electrolytic generation of elemental fluorine are described. The 400 A monel electrolytic cell is heated by a water jacket. The electrolyte has the composition KF.1,8 - 2,0 HF that is maintained by intermittent addition of gaseous HF. Pre-electrolysis is made using nickel anodes which are then exchanged by non-graphitized carbon ones. Systems for purification of elemental fluorine by cryoscopy and absortion of HF, compression and storage for fluorine are described. Pure fluorine is used for the preparation of uranium hexafluoride. Identification of problems and difficulties and their solution are pointed out. (Author) [pt

Driven spin transitions in fluorinated single- and bilayer-graphene quantum dots

Science.gov (United States)

Żebrowski, D. P.; Peeters, F. M.; Szafran, B.

2017-06-01

Spin transitions driven by a periodically varying electric potential in dilute fluorinated graphene quantum dots are investigated. Flakes of monolayer graphene as well as electrostatic electron traps induced in bilayer graphene are considered. The stationary states obtained within the tight-binding approach are used as the basis for description of the system dynamics. The dilute fluorination of the top layer lifts the valley degeneracy of the confined states and attenuates the orbital magnetic dipole moments due to current circulation within the flake. The spin-orbit coupling introduced by the surface deformation of the top layer induced by the adatoms allows the spin flips to be driven by the AC electric field. For the bilayer quantum dots the spin flip times is substantially shorter than the spin relaxation. Dynamical effects including many-photon and multilevel transitions are also discussed.

Macromolecular Networks Containing Fluorinated Cyclic Moieties

Science.gov (United States)

2015-12-12

Briefing Charts 3. DATES COVERED (From - To) 17 Nov 2015 – 12 Dec 2015 4. TITLE AND SUBTITLE Macromolecular Networks Containing Fluorinated Cyclic... FLUORINATED CYCLIC MOIETIES 12 December 2015 Andrew J. Guenthner,1 Scott T. Iacono,2 Cynthia A. Corley,2 Christopher M. Sahagun,3 Kevin R. Lamison,4...Reinforcements Good Flame, Smoke, & Toxicity Characteristics Low Water Uptake with Near Zero Coefficient of Hygroscopic Expansion ∆ DISTRIBUTION A

40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

Science.gov (United States)

2010-07-01

... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under this... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fluorinated carboxylic acid alkali...

Controlled Synthesis of Fluorinated Copolymers with Pendant Sulfonates

DEFF Research Database (Denmark)

Dimitrov, Ivaylo; Jankova Atanasova, Katja; Hvilsted, Søren

2008-01-01

Novel fluorinated copolymers of different architectures and bearing sulfopropyl groups were synthesized by atom transfer radical polymerization (ATRP) of aromatic fluorinated monomers and two modification reactions performed on the polymer chain - demethylation followed by sulfopropylation. As a ...

Simple electrolytic cell for production of elemental fluorine

International Nuclear Information System (INIS)

Dides F, M.; Padilla S, U.

1990-01-01

It was constructed and tested a simple electrolytic cell for the production of elemental fluorine. The fluorine production is essential in the obtainment of uranium hexafluoride, a compound for the nuclear fuel cycle. (A.C.A.S.)

Passivation of fluorinated activated charcoal

Energy Technology Data Exchange (ETDEWEB)

Del Cul, G.D.; Trowbridge, L.D.; Simmons, D.W.; Williams, D.F.; Toth, L.M.

1997-10-01

The Molten Salt Reactor Experiment (MSRE), at the Oak Ridge National Laboratory has been shut down since 1969 when the fuel salt was drained from the core into two Hastelloy N tanks at the reactor site. In 1995, a multiyear project was launched to remediate the potentially hazardous conditions generated by the movement of fissile material and reactive gases from the storage tanks into the piping system and an auxiliary charcoal bed (ACB). The top 12 in. of the ACB is known by gamma scan and thermal analysis to contain about 2.6 kg U-233. According to the laboratory tests, a few feet of fluorinated charcoal are believed to extend beyond the uranium front. The remainder of the ACB should consist of unreacted charcoal. Fluorinated charcoal, when subjected to rapid heating, can decompose generating gaseous products. Under confined conditions, the sudden exothermic decomposition can produce high temperatures and pressures of near-explosive characteristics. Since it will be necessary to drill and tap the ACB to allow installation of piping and instrumentation for remediation and recovery activities, it is necessary to chemically convert the reactive fluorinated charcoal into a more stable material. Ammonia can be administered to the ACB as a volatile denaturing agent that results in the conversion of the C{sub x}F to carbon and ammonium fluoride, NH{sub 4}F. The charcoal laden with NH{sub 4}F can then be heated without risking any sudden decomposition. The only consequence of heating the treated material will be the volatilization of NH{sub 4}F as a mixture of NH{sub 3} and HF, which would primarily recombine as NH{sub 4}F on surfaces below 200 C. The planned scheme for the ACB denaturing is to flow diluted ammonia gas in steps of increasing NH{sub 3} concentration, 2% to 50%, followed by the injection of pure ammonia. This report summarizes the planned passivation treatment scheme to stabilize the ACB and remove the potential hazards. It also includes basic information

Injuries caused to fruit trees by fluorine containing gases

Energy Technology Data Exchange (ETDEWEB)

Bovay, E

1958-01-01

Determinations of chlorine and fluorine have been made on leaves of various fruit trees growing in the vicinity of two factories, the first one being an aluminium factory and the second one a soda factory. The gases released by the first factory are of the fluorine type and those of the second one of the chlorine type. While the concentrations of fluorine are generally higher than 10 mg per 100 g of leaf dry matter, they hardly reached 2.5 mg% in 1957; the aluminium factory was not in operation that year. Moreover no symptoms of burns were observed in 1957 on the leaves of the fruit trees. In contrast to fluorine, the concentrations of chlorine remained constant.

Synthesis, optical properties and photostability of novel fluorinated organic–inorganic hybrid (R–NH3)2PbX4 semiconductors

International Nuclear Information System (INIS)

Wei, Y; Lauret, J-S; Deleporte, E; Audebert, P; Galmiche, L

2013-01-01

We report on the synthesis and the optical properties of several novel semiconductors (R–NH 3 ) 2 PbX 4 (X = Br − , I − or Cl − ). These semiconductors are two-dimensional organic–inorganic perovskite (2DOIP) materials and have multiple quantum-well energy level structures. We vary the organic components (R-NH 3 + ), introducing fluorine atoms into the organic part, on the phenyl ring of the amine. We discuss its influence on the self-organization ability and long-term photostability of the 2DOIPs. The trends of introducing fluorine atoms on the self-organization and long-term photostability of 2DOIPs are obtained by analysing the optical experimental results, and show that the influence of the fluorine position on the benzene ring is quite important. The most promising compounds seem to be the ones with the fluorine atom sitting on the para position of the phenyl group. (paper)

Phytoindication of air pollution by fluorine emissions

Energy Technology Data Exchange (ETDEWEB)

Holub, Z; Kontrisova, O

1973-01-01

Analytical techniques allowing quantitative chemical analysis of toxic materials in leaves are described. The method is specifically designed to examine foliage which has been exposed to fluorine. Naturally occurring plants (angiosperms) are effective as bioindicators of high levels of fluorine pollution, while lichens and/or carefully cultivated plants are more effective as indicators of low levels of F.

Influence of ZrO2 particles on fluorine-doped lead dioxide electrodeposition process from nitrate bath

International Nuclear Information System (INIS)

Yao, Yingwu; Zhou, Tao; Zhao, Chunmei; Jing, Qiming; Wang, Yang

2013-01-01

The influence of ZrO 2 particles on fluorine-doped lead dioxide electrodeposition process on the glass carbon electrode (GCE) from lead nitrate electrolytes was studied by cyclic voltammetry (CV) and chronoamperometry (CA), coupled with the scanning electron microscope (SEM). Instantaneous nucleation mechanism is found for fluorine-doped lead dioxide electrodeposition in the presence of ZrO 2 particles according to Scharifker–Hills’ model with three-dimensional growth. The results show that the addition of ZrO 2 particles decrease the active surface area of the GCE, and the growth of the lead dioxide crystallites was obstructed

Fluorine and Lithium at the Kimberley Outcrop, Gale Crater

Science.gov (United States)

Forni, O.; Vaniman, D. T.; Le Deit, L.; Clegg, S. M.; Lanza, N. L.; Lasue, J.; Bish, D. L.; Mangold, N.; Wiens, R. C.; Meslin, P.-Y.;

Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence.

Science.gov (United States)

Remete, Attila Márió; Nonn, Melinda; Fustero, Santos; Haukka, Matti; Fülöp, Ferenc; Kiss, Loránd

2017-01-01

A study exploring the chemical behavior of some dihydroxylated β-amino ester stereo- and regioisomers, derived from unsaturated cyclic β-amino acids is described. The nucleophilic fluorinations involving hydroxy-fluorine exchange of some highly functionalized alicyclic diol derivatives have been carried out in view of selective fluorination, investigating substrate dependence, neighboring group assistance and chemodifferentiation.

Determination of carbon chlorine and fluorine in uranium dioxide

International Nuclear Information System (INIS)

Kijko, N.I.; Timofeev, G.A.

1983-01-01

Techniques of chlorine and fluorine determination and simultaneous determination of carbon and chlorine in electrolytic uranium dioxide are described. The method of chlorine and fluorine determination is based on their separation during oxide pyrohydrolysis with subsequent spectrophotometric analysis of condensate. Lower determination limits constitute 1 μg for chlorine, 0.5 μg for fluorine. Relative standard deviation when the content of impurities analyzed is 10 -3 % constitutes 0.05-0.07

Surface analysis of graphite fiber reinforced polyimide composites

Science.gov (United States)

Messick, D. L.; Progar, D. J.; Wightman, J. P.

1983-01-01

Several techniques have been used to establish the effect of different surface pretreatments on graphite-polyimide composites. Composites were prepared from Celion 6000 graphite fibers and the polyimide LARC-160. Pretreatments included mechanical abrasion, chemical etching and light irradiation. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used in the analysis. Contact angle of five different liquids of varying surface tensions were measured on the composites. SEM results showed polymer-rich peaks and polymer-poor valleys conforming to the pattern of the release cloth used durng fabrication. Mechanically treated and light irradiated samples showed varying degrees of polymer peak removal, with some degradation down to the graphite fibers. Minimal changes in surface topography were observed on concentrations of surface fluorine even after pretreatment. The light irradiation pretreatment was most effective at reducing surface fluorine concentrations whereas chemical pretreatment was the least effective. Critical surface tensions correlated directly with the surface fluorine to carbon ratios as calculated from XPS.

Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence

Directory of Open Access Journals (Sweden)

Attila Márió Remete

2017-11-01

Full Text Available A study exploring the chemical behavior of some dihydroxylated β-amino ester stereo- and regioisomers, derived from unsaturated cyclic β-amino acids is described. The nucleophilic fluorinations involving hydroxy–fluorine exchange of some highly functionalized alicyclic diol derivatives have been carried out in view of selective fluorination, investigating substrate dependence, neighboring group assistance and chemodifferentiation.

Fluorine-18 labeling of proteins

International Nuclear Information System (INIS)

Kilbourn, M.R.; Dence, C.S.; Welch, M.J.; Mathias, C.J.

1987-01-01

Two fluorine-18-labeled reagents, methyl 3-[ 18 F]fluoro-5-nitrobenzimidate and 4-[ 18 F]fluorophenacyl bromide, have been prepared for covalent attachment of fluorine-18 to proteins. Both reagents can be prepared in moderate yields (30-50%, EOB) in synthesis times of 50-70 min. Reaction of these reagents with proteins (human serum albumin, human fibrinogen, and human immunoglobulin A) is pH independent, protein concentration dependent, and takes 5-60 min at mild pH (8.0) and temperature (25-37 degrees C), in yields up to 95% (corrected). The 18 F-labeled proteins are purified by size exclusion chromatography

Enantioselective catalytic fluorinative aza-semipinacol rearrangement.

Science.gov (United States)

Romanov-Michailidis, Fedor; Pupier, Marion; Besnard, Céline; Bürgi, Thomas; Alexakis, Alexandre

2014-10-03

An efficient and highly stereoselective fluorinative aza-semipinacol rearrangement is described. The catalytic reaction requires use of Selectfluor in combination with the chiral, enantiopure phosphate anion derived from acid L3. Under optimized conditions, cyclopropylamines A were transformed into β-fluoro cyclobutylimines B in good yields and high levels of diastereo- and enantiocontrol. Furthermore, the optically active cyclobutylimines were reduced diastereoselectively with L-Selectride in the corresponding fluorinated amines C, compounds of significant interest in the pharmacological industry.

Gas Sensing of Fluorine Doped Tin Oxide Thin Films Prepared by Spray Pyrolysis

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A. A. YADAV

2008-05-01

Full Text Available Fluorine doped tin oxide (F: SnO2 films have been prepared onto the amorphous glass substrates by a spray pyrolysis. XRD studies reveal that the material deposited is polycrystalline SnO2 and have tetragonal structure. It is observed that films are highly orientated along (200 direction. The direct optical band gap energy for the F: SnO2 films are found to be 4.15 eV. Gas sensing properties of the sensor were checked against combustible gases like H2, CO2 CO, C3H8, CH4.The H2 sensitivity of the F-doped SnO2 sensor was found to be increased. The increase in the sensitivity is discussed in terms of increased resistivity and reduced permeation of gaseous oxygen into the underlying sensing layer due to the surface modification of the sensor.

Fluorine-18 labelled compounds

International Nuclear Information System (INIS)

Kleijn, J.P. de

1978-01-01

The work presented in this thesis deals with the problems involved in the adaption of reactor-produced fluorine-18 to the synthesis of 18 F-labelled organic fluorine compounds. Several 18 F-labelling reagents were prepared and successfully applied. The limitations to the synthetic possibilities of reactor-produced fluoride- 18 become manifest in the last part of the thesis. An application to the synthesis of labelled aliphatic fluoro amino acids has appeared to be unsuccessful as yet, although some other synthetic approaches can be indicated. Seven journal articles (for which see the availability note) are used to compose the four chapters and three appendices. The connecting text gives a survey of known 18 F-compounds and methods for preparing such compounds. (Auth.)

Consultants' meeting on reactor production and utilization of Fluorine-18

International Nuclear Information System (INIS)

Vera Ruiz, H.

1986-08-01

The nuclear research reactors with thermal neutron fluxes in the order of 1x10 13 cm -2 s -1 can produce sufficient quantities of fluorine-18 for biomedical applications. The recent improvements in labelling with fluorine-18 via nucleophilic reactions have made it possible to develop efficient synthesis techniques for preparing useful quantities of radiopharmaceuticals, which are of great interest for studying regional metabolic functions with positron emission tomography. Other non-medical activities in the field of pharmacology, toxicology, no-carrier-added syntheses and reaction mechanisms in fluorine chemistry can also conveniently be studied using fluorine-18 as a tracer

Surface Modification of MXenes: A Pathway to Improve MXene Electrode Performance in Electrochemical Energy Storage Devices

KAUST Repository

Ahmed, Bilal

2017-12-31

The recent discovery of layered transition metal carbides (MXenes) is one of the most important developments in two-dimensional (2D) materials. Preliminary theoretical and experimental studies suggest a wide range of potential applications for MXenes. The MXenes are prepared by chemically etching ‘A’-layer element from layered ternary metal carbides, nitrides and carbonitrides (MAX phases) through aqueous acid treatment, which results in various surface terminations such as hydroxyl, oxygen or fluorine. It has been found that surface terminations play a critical role in defining MXene properties and affects MXene performance in different applications such as electrochemical energy storage, electromagnetic interference shielding, water purification, sensors and catalysis. Also, the electronic, thermoelectric, structural, plasmonic and optical properties of MXenes largely depend upon surface terminations. Thus, controlling the surface chemistry if MXenes can be an efficient way to improve their properties. This research mainly aims to perform surface modifications of two commonly studied MXenes; Ti2C and Ti3C2, via chemical, thermal or physical processes to enhance electrochemical energy storage properties. The as-prepared and surface modified MXenes have been studied as electrode materials in Li-ion batteries (LIBs) and supercapacitors (SCs). In pursuit of desirable MXene surface, we have developed an in-situ room temperature oxidation process, which resulted in TiO2/MXene nanocomposite and enhanced Li-ion storage. The idea of making metal oxide and MXene nanocomposites was taken to the next level by combining a high capacity anode materials – SnO2 – and MXene. By taking advantage of already existing surface functional groups (–OH), we have developed a composite of SnO2/MXene by atomic layer deposition (ALD) which showed enhanced capacity and excellent cyclic stability. Thermal annealing of MXene at elevated temperature under different atmospheres was

Effect of nitrogen and fluorine on mechanical properties and bioactivity in two series of bioactive glasses.

Science.gov (United States)

Bachar, Ahmed; Mercier, Cyrille; Tricoteaux, Arnaud; Hampshire, Stuart; Leriche, Anne; Follet, Claudine

2013-07-01

Bioactive glasses are able to bond to bone through formation of carbonated hydroxyapatite in body fluids, and fluoride-releasing bioactive glasses are of interest for both orthopaedic and, in particular, dental applications for caries inhibition. However, because of their poor strength their use is restricted to non-load-bearing applications. In order to increase their mechanical properties, doping with nitrogen has been performed on two series of bioactive glasses: series (I) was a "bioglass" composition (without P2O5) within the quaternary system SiO2-Na2O-CaO-Si3N4 and series (II) was a simple substitution of CaF2 for CaO in series (I) glasses keeping the Na:Ca ratio constant. The objective of this work was to evaluate the effect of the variation in nitrogen and fluorine content on the properties of these glasses. The density, glass transition temperature, hardness and elastic modulus all increased linearly with nitrogen content which indicates that the incorporation of nitrogen stiffens the glass network because N is mainly in 3-fold coordination with Si atoms. Fluorine addition significantly decreases the thermal property values but the mechanical properties of these glasses remain unchanged with fluorine. The combination of both nitrogen and fluorine in oxyfluoronitride glasses gives better mechanical properties at much lower melting temperatures since fluorine reduces the melting point, allows higher solubility of nitrogen and does not affect the higher mechanical properties arising from incorporation of nitrogen. The characterization of these N and F substituted bioactive glasses using (29)Si MAS NMR has shown that the increase in rigidity of the glass network can be explained by the formation of SiO3N, SiO2N2 tetrahedra and Q(4) units with extra bridging anions at the expense of Q(3) units. Bioactivity of the glasses was investigated in vitro by examining apatite formation on the surface of glasses treated in acellular simulated body fluid (SBF) with ion

The Comparison of Biocompatibility Properties between Ti Alloys and Fluorinated Diamond-Like Carbon Films

Directory of Open Access Journals (Sweden)

Chavin Jongwannasiri

2012-01-01

Full Text Available Titanium and titanium alloys have found several applications in the biomedical field due to their unique biocompatibility. However, there are problems associated with these materials in applications in which there is direct contact with blood, for instance, thrombogenesis and protein adsorption. Surface modification is one of the effective methods used to improve the performance of Ti and Ti alloys in these circumstances. In this study, fluorinated diamond-like carbon (F-DLC films are chosen to take into account the biocompatible properties compared with Ti alloys. F-DLC films were prepared on NiTi substrates by a plasma-based ion implantation (PBII technique using acetylene (C2H2 and tetrafluoromethane (CF4 as plasma sources. The structure of the films was characterized by Raman spectroscopy. The contact angle and surface energy were also measured. Protein adsorption was performed by treating the films with bovine serum albumin and fibrinogen. The electrochemical corrosion behavior was investigated in Hanks’ solution by means of a potentiodynamic polarization technique. Cytotoxicity tests were performed using MTT assay and dyed fluorescence. The results indicate that F-DLC films present their hydrophobic surfaces due to a high contact angle and low surface energy. These films can support the higher albumin-to-fibrinogen ratio as compared to Ti alloys. They tend to suppress the platelet adhesion. Furthermore, F-DLC films exhibit better corrosion resistance and less cytotoxicity on their surfaces. It can be concluded that F-DLC films can improve the biocompatibility properties of Ti alloys.

Proton activation analysis for the measurement of fluorine in food stamples

International Nuclear Information System (INIS)

Shroy, R.E.; Kraner, H.W.; Jones, K.W.; Jacobson, J.S.; Heller, L.I.

1982-01-01

We have developed a proton activation method for the determination of 19 F in food samples based on the use of the 19 F(p,p'γ) 19 F reaction. Special techniques were used to obtain reproducible target conditions and low background values. Two calibration techniques not dependent on chemical analyses for fluorine gave values comparable to a third method which employed vegetation and cellulose containing from about 20 to 500 ppM (μg/g dry weight) of fluorine. Results are reported for FDA market basket food samples containing less than 10 ppM fluorine (dry weight) and are compared with the values obtained with two methods of chemical analysis for both vegetation and food samples. Proton activation and chemical methods gave values in excellent agreement for the fluorine content of the high fluorine vegetation samples; however, substantial disagreement remains for the low-fluorine food samples

Effects of fluorine on the germination of some species of seeds

Energy Technology Data Exchange (ETDEWEB)

Navara, J; Holub, Z; Bedatsova, L

1966-01-01

The various degrees of tolerance of the seeds of some species of plants towards fluorine and their ability to accumulate fluorine under experimental conditions are presented. The effects of fluorine on the germination of seeds manifests itself in various ways. The studied species have been divided into four groups according to their natural tolerance: (1) very sensitive: pea, soya, vetch and cabbage; (2) sensitive: radish, barley, cole; (3) less sensitive: maize, cauliflower, alfalfa, mustard, oats, clover kohlrabi; and (4) tolerant: poppy, carrot, tomato. Highly tolerant species are capable of accumulating considerable amounts of fluorine when compared with the more sensitive species. A more intensive accumulation of fluorine has been noticed in the oleaginous species, viz. mustard and poppy. A correlation was found to exist between the ash contents (especially of calcium) and the ability of a greater accumulation of fluorine. 23 references, 6 figures, 2 tables.

Facing the rain after the phase out: Performance evaluation of alternative fluorinated and non-fluorinated durable water repellents for outdoor fabrics.

Science.gov (United States)

Schellenberger, S; Gillgard, P; Stare, A; Hanning, A; Levenstam, O; Roos, S; Cousins, I T

2018-02-01

Fluorinated durable water repellent (DWR) agents are used to obtain water and stain repellent textiles. Due to the on-going phase-out of DWRs based on side-chain fluorinated polymers (SFP) with "long" perfluoroalkyl chains, the textile industry lacks suitable alternatives with comparable material characteristics. The constant development and optimization of SFPs for textile applications initiated more than half a century ago has resulted in a robust and very efficient DWR-technology and textiles with exceptional hydro- and oleo-phobic properties. The industry is now in the predicament that the long-chain SFPs with the best technical performance have undesirable toxicological and environmental behaviour. This study provides a comprehensive overview of the technical performance of presently available fluorinated and non-fluorinated DWRs as part of a chemical alternatives assessment (CAA). The results are based on a study with synthetic outdoor fabrics treated with alternative DWRs and tested for repellency using industrial standard and complementary methods. Using this approach, the complex structure-property relationships of DWR-polymers could be explained on a molecular level. Both short-chain SFPs and non-fluorinated DWRs showed excellent water repellency and durability in some cases while short-chain SFPs were the more robust of the alternatives to long-chain SFPs. A strong decline in oil repellency and durability with perfluoroalkyl chain length was shown for SFP DWRs. Non-fluorinated alternatives were unable to repel oil, which might limit their potential for substitution in textile application that require repellency towards non-polar liquids. Copyright © 2017. Published by Elsevier Ltd.

Quantitative monitoring of the fluorination process by neutron counting

International Nuclear Information System (INIS)

Russo, P.A.; Appert, Q.D.; Biddle, R.S.; Kelley, T.A.; Martinez, M.M.; West, M.H.

1993-01-01

Plutonium metal is produced by reducing PuF 4 prepared from PuO 2 by fluorination. Both fluorination and reduction are batch processes at the Los Alamos Plutonium Facility. The conversion of plutonium oxide to fluoride greatly increases the neutron yield, a result of the high cross section for alpha-neutron (α,n) reactions on fluorine targets compared to the (more than 100 times) smaller α,n yield on oxygen targets. Because of the increase, total neutron counting can be used to monitor the conversion process. This monitoring ability can lead to an improved metal product, reduced scrap for recycle, waste reduction, minimized reagent usage, and reduce personnel radiation exposures. A new stirred-bed fluorination process has been developed simultaneously with a recent evaluation of an automated neutron-counting instrument for quantitative process monitoring. Neutrons are counted with polyethylene-moderated 3 He-gas proportional counters. Results include a calibration of the real-time neutron-count-rate indicator for the extent of fluorination using reference values obtained from destructive analysis of samples from the blended fluoroinated batch

Novel Fluorinated Indanone, Tetralone and Naphthone Derivatives: Synthesis and Unique Structural Features

Directory of Open Access Journals (Sweden)

Joseph C. Sloop

2012-02-01

Full Text Available Several fluorinated and trifluoromethylated indanone, tetralone and naphthone derivatives have been prepared via Claisen condensations and selective fluorinations in yields ranging from 22–60%. In addition, we report the synthesis of new, selectively fluorinated bindones in yields ranging from 72–92%. Of particular interest is the fluorination and trifluoroacetylation regiochemistry observed in these fluorinated products. We also note unusual transformations including a novel one pot, dual trifluoroacetylation, trifluoroacetylnaphthone synthesis via a deacetylation as well as an acetyl-trifluoroacetyl group exchange. Solid-state structural features exhibited by these compounds were investigated using crystallographic methods. Crystallographic results, supported by spectroscopic data, show that trifluoroacetylated ketones prefer a chelated cis-enol form whereas fluorinated bindone products exist primarily as the cross-conjugated triketo form.

Defects in silicon carbide grown by fluorinated chemical vapor deposition chemistry

Science.gov (United States)

Stenberg, Pontus; Booker, Ian D.; Karhu, Robin; Pedersen, Henrik; Janzén, Erik; Ivanov, Ivan G.

2018-04-01

Point defects in n- and p-type 4H-SiC grown by fluorinated chemical vapor deposition (CVD) have been characterized optically by photoluminescence (PL) and electrically by deep-level transient spectroscopy (DLTS) and minority carrier transient spectroscopy (MCTS). The results are considered in comparison with defects observed in non-fluorinated CVD growth (e.g., using SiH4 instead of SiF4 as silicon precursor), in order to investigate whether specific fluorine-related defects form during the fluorinated CVD growth, which might prohibit the use of fluorinated chemistry for device-manufacturing purposes. Several new peaks identifying new defects appear in the PL of fluorinated-grown samples, which are not commonly observed neither in other halogenated chemistries, nor in the standard CVD chemistry using silane (SiH4). However, further investigation is needed in order to determine their origin and whether they are related to incorporation of F in the SiC lattice, or not. The electric characterization does not find any new electrically-active defects that can be related to F incorporation. Thus, we find no point defects prohibiting the use of fluorinated chemistry for device-making purposes.

Clinical perspectives of hybrid proton-fluorine magnetic resonance imaging and spectroscopy.

Science.gov (United States)

Wolters, Martijn; Mohades, Seyede G; Hackeng, Tilman M; Post, Mark J; Kooi, Marianne E; Backes, Walter H

2013-05-01

The number of applications of fluorine 19 (19F) magnetic resonance (MR) imaging and spectroscopy in biomedical and clinical research is steadily growing. The 100% natural abundance of fluorine and its relatively high sensitivity for MR (83% to that of protons) make it an interesting nucleus for a wide range of MR applications. Fluorinated contrast media have a number of advantages over the conventionally used gadolinium-based or iron-based contrast agents. The absence of an endogenous fluorine background intensity in the human body facilitates reliable quantification of fluorinated contrast medium or drugs. Anatomy can be visualized separately with proton MR imaging, creating the application of hybrid hydrogen 1 (1H)/19F MR imaging. The availability of 2 channels (ie, the 1H and 19F channels) enables dual-targeted molecular imaging. Recently, novel developments have emerged on fluorine-based contrast media in preclinical studies and imaging techniques. The developments in fluorine MR seem promising for clinical applications, with contributions in therapy monitoring, assessment of lung function, angiography, and molecular imaging. This review outlines the translation from recent advances in preclinical MR imaging and spectroscopy to future perspectives of clinical hybrid 1H/19/F MR imaging applications.

Possibilities of nondestructive determination of fluorine in coal and biological materials by IPAA

International Nuclear Information System (INIS)

Randa, Zdenek; Mizera, Jiri; Chvatil, David

2009-01-01

The possibilities of nondestructive determination of fluorine in coal and biological materials by instrumental photon activation analysis (IPAA) were studied. The determination was based on counting the non-specific 511 keV annihilation gamma rays of 18 F, a pure positron emitter which is the product of the photonuclear reaction 19 F(γ, n) 18 F. The simultaneous formation of some additional positron emitters, particularly 45 Ti and 34m Cl, is an interfering factor. When using correction standards for Ti and Cl and optimization of the beam energy and irradiation-decay-counting times, fluorine could be determined by IPAA in selected coal and biological samples at the ten ppm level. The feasibility of additional optimization for further improvements of the proposed IPAA procedure are discussed

Effect of Nitrogen Fertilizer on Combined Forms and Transformation of Fluorine in Tea Garden Soil

Directory of Open Access Journals (Sweden)

ZHANG Yong-li

2015-10-01

Full Text Available In order to investigate the effect of nitrogen fertilizer on combined forms and transformation of fluorine in tea garden soil, soil pot experiment was carried out. The research object was red-yellow soil in Shizipu tea plantation in the south of Anhui Province. Five treatments were N0P0K0 (CK, N0P1K1 (N0, N1P1K1 (N1, N2P1K1 (N2, N3P1K1 (N3. Water-soluble fluorine content, exchangeable fluorine content, Fe/Mn oxide-bound fluorine content, organic matter-bound fluorine content, ammonium nitrogen content and soil pH value in 0~15 cm soil layer were analyzed in 10, 20, 30, 50, 70, 90 days after fertilization. The results showed that compared with CK, in the short term (10 or 20 days after applying NPK, the content of water-soluble fluorine in 0~15 cm soil layer was decreased and the content of exchangeable fluorine, Fe/Mn oxide-bound fluorine and organic matter-bound fluorine were increased. After 20 days, the content of soil water-soluble fluorine was increased and the content of soil exchangeable fluorine, Fe/Mn oxide-bound fluorine and organic matter-bound fluorine were reduced. The effect on water-soluble fluorine and exchangeable fluorine increased with time and the application rate of nitrogen. The content of water-soluble fluorine in tea garden soil had a moderately positive correlation with the application rate of nitrogen while the content of exchangeable fluorine had a moderately or highly negative correlation with the application rate of nitrogen. The content of water-soluble fluorine had a quite highly negative correlation with the soil pH (P<0.01, but the content of exchangeable fluorine had a moderately or highly negative correlation with the soil pH (P<0.01. Therefore, nitrogen fertilizer changed the soil pH during its form transformation and thus affected the transformation and the availability of fluorine in soil.

Rapid synthesis of maleimide functionalized fluorine-18 labeled prosthetic group using "radio-fluorination on the Sep-Pak" method.

Science.gov (United States)

Basuli, Falguni; Zhang, Xiang; Jagoda, Elaine M; Choyke, Peter L; Swenson, Rolf E

2018-03-25

Following our recently published fluorine-18 labeling method, "Radio-fluorination on the Sep-Pak", we have successfully synthesized 6-[ 18 F]fluoronicotinaldehyde by passing a solution (1:4 acetonitrile: t-butanol) of its quaternary ammonium salt precursor, 6-(N,N,N-trimethylamino)nicotinaldehyde trifluoromethanesulfonate (2), through a fluorine-18 containing anion exchange cartridge (PS-HCO 3 ). Over 80% radiochemical conversion was observed using 10 mg of precursor within 1 minute. The [ 18 F]fluoronicotinaldehyde ([ 18 F]5) was then conjugated with 1-(6-(aminooxy)hexyl)-1H-pyrrole-2,5-dione to prepare the fluorine-18 labeled maleimide functionalized prosthetic group, 6-[ 18 F]fluoronicotinaldehyde O-(6-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)hexyl) oxime, 6-[ 18 F]FPyMHO ([ 18 F]6). The current Sep-Pak method not only improves the overall radiochemical yield (50 ± 9%, decay-corrected, n = 9) but also significantly reduces the synthesis time (from 60-90 minutes to 30 minutes) when compared with literature methods for the synthesis of similar prosthetic groups. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Interfacial and Electrical Properties of Ge MOS Capacitor by ZrLaON Passivation Layer and Fluorine Incorporation

Science.gov (United States)

Huang, Yong; Xu, Jing-Ping; Liu, Lu; Cheng, Zhi-Xiang; Lai, Pui-To; Tang, Wing-Man

2017-09-01

Ge Metal-Oxide-Semiconductor (MOS) capacitor with HfTiON/ZrLaON stacked gate dielectric and fluorine-plasma treatment is fabricated, and its interfacial and electrical properties are compared with its counterparts without the ZrLaON passivation layer or the fluorine-plasma treatment. Experimental results show that the sample exhibits excellent performances: low interface-state density (3.7×1011 cm-2eV-1), small flatband voltage (0.21 V), good capacitance-voltage behavior, small frequency dispersion and low gate leakage current (4.41×10-5 A/cm2 at Vg = Vfb + 1V). These should be attributed to the suppressed growth of unstable Ge oxides on the Ge surface during gate-dielectric annealing by the ZrLaON interlayer and fluorine incorporation, thus greatly reducing the defective states at/near the ZrLaON/Ge interface and improving the electrical properties of the device.

Fluorinated Amine Stereotriads via Allene Amination.

Science.gov (United States)

Liu, Lu; Gerstner, Nels C; Oxtoby, Lucas J; Guzei, Ilia A; Schomaker, Jennifer M

2017-06-16

The incorporation of fluorine into organic scaffolds often improves the bioactivity of pharmaceutically relevant compounds. C-F/C-N/C-O stereotriad motifs are prevalent in antivirals, neuraminidase inhibitors, and modulators of androgen receptors, but are challenging to install. An oxidative allene amination strategy using Selectfluor rapidly delivers triply functionalized triads of the form C-F/C-N/C-O, exhibiting good scope and diastereoselectivity for all syn products. The resulting stereotriads are readily transformed into fluorinated pyrrolidines and protected α-, β-, and γ-amino acids.

Inversed linear dichroism in F K-edge NEXAFS spectra of fluorinated planar aromatic molecules

DEFF Research Database (Denmark)

de Oteyza, D. G.; Sakko, A.; El-Sayed, A.

2012-01-01

The symmetry and energy distribution of unoccupied molecular orbitals is addressed in this work by means of NEXAFS and density functional theory calculations for planar, fluorinated organic semiconductors (perfluorinated copper phthalocyanines and perfluoropentacene). We demonstrate how molecular...

Geminal difunctionalization of α-diazo arylmethylphosphonates: synthesis of fluorinated phosphonates.

Science.gov (United States)

Zhou, Yujing; Zhang, Yan; Wang, Jianbo

2016-11-08

A general approach towards diverse fluorinated phosphonates via geminal difunctionalization reactions of α-diazo arylmethylphosphonates is described. The diazo functionality (RR'C[double bond, length as m-dash]N 2 ) is successfully converted to RR'CF 2 , RR'CHF, RR'CFBr or RR'CFNR'' 2 groups by employing different fluorination reagents. A variety of fluorinated organophosphorus compounds were readily accessed in good to excellent yields from a common type of precursor.

Fluorine level in some city water supplies of Bangladesh

International Nuclear Information System (INIS)

Hoque, A.K.M.F.; Abedin, M.J.; Rahman, M.M.; Mia, M. Y.; Tarafder, M.S.A.; Khaliquzzaman, M.; Hossain, M.D.; Khan, A.H.

2003-01-01

Nuclear reaction based Proton Induced Gamma Emission (PIGE) analytical method was employed for the quantitative measurement of fluorine in the city water supplies of the major cities of Bangladesh. 102 water samples collected from 14 city supplies were analyzed and these samples contain fluorine in the range of 0.03 to 1.10 mg/L with a mean of 0.33 ± 0.21 mg/L. It was also observed that except the samples of Barisal, Dinajpur and Rajshahi, all other water samples analyzed contain a much lower amount of fluorine than the maximum permissible value for Bangladesh in drinking water, which is 1 mg/L. The mean concentration of fluorine in the samples of Barisal, Dinajpur and Rajshahi are respectively 0.79±0.01, 0.71±0.13 and 0.92±0.18 mg/L. For the 55 samples of Dhaka city supply the mean fluorine concentration is 0.31±0.17 mg/L and that of 9 samples from Chittagong city supply is 0.19±0.10 mg/L, which is the lowest among the 14 city supply samples analyzed in this study

Investigating the Influence of (Deoxy)fluorination on the Lipophilicity of Non-UV-Active Fluorinated Alkanols and Carbohydrates by a New log P Determination Method.

Science.gov (United States)

Linclau, Bruno; Wang, Zhong; Compain, Guillaume; Paumelle, Vincent; Fontenelle, Clement Q; Wells, Neil; Weymouth-Wilson, Alex

2016-01-11

Property tuning by fluorination is very effective for a number of purposes, and currently increasingly investigated for aliphatic compounds. An important application is lipophilicity (log P) modulation. However, the determination of log P is cumbersome for non-UV-active compounds. A new variation of the shake-flask log P determination method is presented, enabling the measurement of log P for fluorinated compounds with or without UV activity regardless of whether they are hydrophilic or lipophilic. No calibration curves or measurements of compound masses/aliquot volumes are required. With this method, the influence of fluorination on the lipophilicity of fluorinated aliphatic alcohols was determined, and the log P values of fluorinated carbohydrates were measured. Interesting trends and changes, for example, for the dependence on relative stereochemistry, are reported. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

40 CFR 721.10146 - Partially fluorinated condensation polymer (generic).

Science.gov (United States)

2010-07-01

... polymer (generic). 721.10146 Section 721.10146 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10146 Partially fluorinated condensation polymer (generic). (a) Chemical... as partially fluorinated condensation polymer (PMN P-07-87) is subject to reporting under this...

Study of mass and momentum transfer and their effect on the direct fluorination of uranium oxide

International Nuclear Information System (INIS)

Cross, P.E.

1983-01-01

The mechanism for the fluorination of solid U 3 O 8 to gaseous UF 6 was found to be a two-step process with solid UO 2 F 2 as an intermediate. The highest particle temperatures were found to be associated with the initial reaction step to UO 2 F 2 ; it was recommended that these temperatures be maintained below 1700 0 F. The chemical equilibrium constant for the fluorination of PuF 4 to PuF 6 was found to be unexpectedly low at typical flame tower temperatures. Although not confirmed, there is an indication in the literature that a similar equilibrium constant is associated with the fluorination of NpF 4 and other transuranic molecules. It was recommended that uranium oxides which are significantly contaminated with transuranics should not be processed through a direct fluorination reactor such as the UF 6 flame tower. Reaction rate equations were developed for the fluorination of U 3 O 8 , UF 4 , PuF 4 and NpF 4 . During the course of the development, a significant discrepancy was found in the literature for the activation energy of the fluorination of U 3 O 8 . Equations were developed for both a high and low limit rate constant for the fluorination of U 3 O 8 . A variey of momentum, heat and mass transfer equations were developed for both oxide particles and the gas phase within the flame tower. Equations were developed to estimate the physical and transport properties of each gaseous component and the gas mixture as a whole. These properties and the transport equations were used to estimate the reaction time and distance for oxide particles with both the low and high limit reaction rate constant. The procedures used to perform these calculations is limited to constant temperature and an oxide feed comprised of a single particle size. The results indicate that above 1000 0 F the mass transfer of reactants and products becomes increasingly important to the overall rate of the reaction

Roles of fluorine and annealing on optical and structural properties of Nd:YF{sub 3} phosphor

Energy Technology Data Exchange (ETDEWEB)

Santos, H.D.A.; Novais, S.M.V.; Jacinto, C., E-mail: cjacinto@fis.ufal.br

2016-07-15

The optical and structural properties of Nd:YF{sub 3} phosphors, synthesized by precipitation reaction using ethylene glycol solvent, were investigated. The Y:F molar ratio of precursors, where NH{sub 4}F was employed as the fluorine source, was varied to prevent oxygen contamination during nucleation of the particles and to improve the photoluminescence efficiency. Structural investigations were carried out by means of X-ray diffraction, Fourier transform infrared spectroscopy and energy dispersive X-ray techniques. Samples prepared using precursors in stoichiometric proportion presented orthorhombic YF{sub 3} structure. The use of fluorine source in excess promoted formation of NH{sub 4}Y{sub 2}F{sub 7} crystalline phase, which was decomposed into YF{sub 3} after annealing at 400 °C for 1 h. Emission spectra of samples thermally treated enhanced by over 50 times compared with the as prepared. The results obtained show the role of fluorine excess associated with thermal annealing to obtain YF{sub 3} with improved features.

Internal energy deposition with silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry

Science.gov (United States)

Dagan, Shai; Hua, Yimin; Boday, Dylan J.; Somogyi, Arpad; Wysocki, Ronald J.; Wysocki, Vicki H.

2009-06-01

The use of silicon nanoparticles for laser desorption/ionization (LDI) is a new appealing matrix-less approach for the selective and sensitive mass spectrometry of small molecules in MALDI instruments. Chemically modified silicon nanoparticles (30 nm) were previously found to require very low laser fluence in order to induce efficient LDI, which raised the question of internal energy deposition processes in that system. Here we report a comparative study of internal energy deposition from silicon nanoparticles to previously explored benzylpyridinium (BP) model compounds during LDI experiments. The internal energy deposition in silicon nanoparticle-assisted laser desorption/ionization (SPALDI) with different fluorinated linear chain modifiers (decyl, hexyl and propyl) was compared to LDI from untreated silicon nanoparticles and from the organic matrix, [alpha]-cyano-4-hydroxycinnamic acid (CHCA). The energy deposition to internal vibrational modes was evaluated by molecular ion survival curves and indicated that the ions produced by SPALDI have an internal energy threshold of 2.8-3.7 eV. This is slightly lower than the internal energy induced using the organic CHCA matrix, with similar molecular survival curves as previously reported for LDI off silicon nanowires. However, the internal energy associated with desorption/ionization from the silicon nanoparticles is significantly lower than that reported for desorption/ionization on silicon (DIOS). The measured survival yields in SPALDI gradually decrease with increasing laser fluence, contrary to reported results for silicon nanowires. The effect of modification of the silicon particle surface with semifluorinated linear chain silanes, including fluorinated decyl (C10), fluorinated hexyl (C6) and fluorinated propyl (C3) was explored too. The internal energy deposited increased with a decrease in the length of the modifier alkyl chain. Unmodified silicon particles exhibited the highest analyte internal energy

Fluorine Gauche Effect Explained by Electrostatic Polarization Instead of Hyperconjugation: An Interacting Quantum Atoms (IQA) and Relative Energy Gradient (REG) Study.

Science.gov (United States)

Thacker, Joseph C R; Popelier, Paul L A

2018-02-08

We present an interacting quantum atoms (IQA) study of the gauche effect by comparing 1,2-difluoroethane, 1,2-dichloroethane, and three conformers of 1,2,3,4,5,6-hexafluorocyclohexane. In the 1,2-difluoroethane, the gauche effect is observed in that the gauche conformation is more stable than the anti, whereas in 1,2-dichloroethane the opposite is true. The analysis performed here is exhaustive and unbiased thanks to using the recently introduced relative energy gradient (REG) method [ Thacker , J. C. R. ; Popelier , P. L. A. Theor. Chem. Acc . 2017 , 136 , 86 ], as implemented in the in-house program ANANKE. We challenge the common explanation that hyperconjugation is responsible for the gauche stability in 1,2-difluoroethane and instead present electrostatics as the cause of gauche stability. Our explanation of the gauche effect is also is seen in other molecules displaying local gauche conformations, such as the recently synthesized "all-cis" hexafluorocyclohexane and its conformers where all the fluorine atoms are in the equatorial positions. Using our extension of the traditional IQA methodology that allows for the partitioning of electrostatic terms into polarization and charge transfer, we propose that the cause of gauche stability is 1,3 C···F electrostatic polarization interactions. In other words, if a number of fluorine atoms are aligned, then the stability due to polarization of nearby carbon atoms is increased.

Patterned hydrophobic and hydrophilic surfaces of ultra-smooth nanocrystalline diamond layers

Energy Technology Data Exchange (ETDEWEB)

Mertens, M., E-mail: michael.mertens@uni-ulm.de [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Mohr, M.; Brühne, K.; Fecht, H.J. [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Łojkowski, M.; Święszkowski, W. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Łojkowski, W. [Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw (Poland)

2016-12-30

Highlights: • Hydrophobic and hydrophilic properties on fluorine-, hydrogen- and oxygen- terminated ultra-nanocrystalline diamond films. • Micropatterned - multi-terminated layers with both hydrophobic and hydrophilic areas on one sample. • Visualization of multi-terminated surfaces by e.g. SEM and LFM. • Roughness and friction investigations on different terminated surfaces. • Smooth and biocompatible surfaces with same roughness regardless of hydrophobicity for microbiological investigations. - Abstract: In this work, we show that ultra nanocrystalline diamond (UNCD) surfaces have been modified to add them hydrophobic and hydrophilic properties. The nanocrystalline diamond films were deposited using the hot filament chemical vapor deposition (HFCVD) technique. This allows growing diamond on different substrates which can be even 3D or structured. Silicon and, for optical applications, transparent quartz glass are the preferred substrates for UNCD layers growth. Fluorine termination leads to strong hydrophobic properties as indicated by a high contact angle for water of more than 100°. Hydrogen termination shows lesser hydrophobic behavior. Hydrophilic characteristics has been realised with oxygen termination. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) measurements confirm the oxygen and fluorine- termination on the nanocrystalline diamond surface. Further, by micropatterning using photolithography, multi-terminated layers have been created with both hydrophobic and hydrophilic areas. In addition, we have shown that retermination is achieved, and the properties of the surface have been changed from hydrophobic to hydrophilic and vice versa. Micro- roughness and stress in the grown film influences slightly the wetting angle as well. The opportunity to realize local differences in hydrophobicity on nanocrystalline diamond layers, in any size or geometry, offers interesting applications for example in

Deposition of tin oxide doped with fluorine produced by sol-gel method and deposited by spray-pyrolysis

International Nuclear Information System (INIS)

Maia, Paulo Herbert Franca; Lima, Francisco Marcone; Sena, Aline Cosmo de; Silva, Alvaro Neuton; Almeida, Ana Fabiola Leite de; Freire, Francisco Nivaldo Aguiar

2014-01-01

Solar energy is one of the most important sources of renewable energy today, but its production is based on silicon cells, expensive and difficult to produce, so the research seek new materials to replace them. This work aims to deposit tin oxide doped with fluorine on the glass substrate using the sol-gel method to provide a working solution and spray pyrolysis technique to perform the deposition. F-SnO2 (FTO) were synthesized by sol-gel method, employing NH_4F and SnCl_2 precursor in an ethanol solution. Before the formation of the gel phase, the entire solution was sprayed, with the aid of a pistol aerographic substrate under heated at 600 °C divided by 50 applications and cooled in the furnace. The substrates had resistances between 10 and 30 S.cm. The energy dispersive x-ray (EDS) revealed the presence of fluorine in the SnO_2 network. (author)

The fluorine destruction in stars: First experimental study of the {sup 19}F(p,{alpha}){sup 16}O reaction at astrophysical energies

Energy Technology Data Exchange (ETDEWEB)

La Cognata, M.; Mukhamedzhanov, A.; Spitaleri, C.; Indelicato, I.; Aliotta, M.; Burjan, V.; Cherubini, S.; Coc, A.; Gulino, M.; Hons, Z.; Kiss, G. G.; Kroha, V.; Lamia, L.; Mrazek, J.; Palmerini, S.; Piskor, S.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S. [INFN-LNS, Catania (Italy); Cyclotron Institute, Texas A and M University, College Station, Texas (United States); University of Catania and INFN-LNS, Catania (Italy); and others

2012-11-12

The {sup 19}F(p,{alpha}){sup 16}O reaction is an important fluorine destruction channel in the proton-rich outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogendeficient post-AGB star nucleosynthesis. So far, available direct measurements do not reach the energy region of astrophysical interest (E{sub cm}{approx} 300 keV), because of the hindrance effect of the Coulomb barrier. The Trojan Horse (TH) method was thus used to access this energy region, by extracting the quasi-free contribution to the {sup 2}H({sup 19}F,{alpha}{sup 16}O)n reaction. The TH measurement of the {alpha}{sub 0} channel, which is the dominant one at such energies, shows the presence of resonant structures not observed before that cause an increase of the reaction rate at astrophysical temperatures up to a factor of 1.7, with potential important consequences for stellar nucleosynthesis.

Recent advances in fluorination techniques and their anticipated impact on drug metabolism and toxicity.

Science.gov (United States)

Murphy, Cormac D; Sandford, Graham

2015-04-01

Fluorine's unique physicochemical properties make it a key element for incorporation into pharmacologically active compounds. Its presence in a drug can alter a number of characteristics that affect ADME-Tox, which has prompted efforts at improving synthetic fluorination procedures. This review describes the influence of fluorine on attributes such as potency, lipophilicity, metabolic stability and bioavailablility and how the effects observed are related to the physicochemical characteristics of the element. Examples of more recently used larger scale synthetic methods for introduction of fluorine into drug leads are detailed and the potential for using biological systems for fluorinated drug production is discussed. The synthetic procedures for carbon-fluorine bond formation largely still rely on decades-old technology for the manufacturing scale and new reagents and methods are required to meet the demands for the preparation of structurally more complex drugs. The improvement of in vitro and computational methods should make fluorinated drug design more efficient and place less emphasis on approaches such as fluorine scanning and animal studies. The introduction of new fluorinated drugs, and in particular those that have novel fluorinated functional groups, should be accompanied by rigorous environmental assessment to determine the nature of transformation products that may cause ecological damage.

Investigating H₂ Sorption in a Fluorinated Metal-Organic Framework with Small Pores Through Molecular Simulation and Inelastic Neutron Scattering.

Science.gov (United States)

Forrest, Katherine A; Pham, Tony; Georgiev, Peter A; Pinzan, Florian; Cioce, Christian R; Unruh, Tobias; Eckert, Juergen; Space, Brian

2015-07-07

Simulations of H2 sorption were performed in a metal-organic framework (MOF) consisting of Zn(2+) ions coordinated to 1,2,4-triazole and tetrafluoroterephthalate ligands (denoted [Zn(trz)(tftph)] in this work). The simulated H2 sorption isotherms reported in this work are consistent with the experimental data for the state points considered. The experimental H2 isosteric heat of adsorption (Qst) values for this MOF are approximately 8.0 kJ mol(-1) for the considered loading range, which is in the proximity of those determined from simulation. The experimental inelastic neutron scattering (INS) spectra for H2 in [Zn(trz)(tftph)] reveal at least two peaks that occur at low energies, which corresponds to high barriers to rotation for the respective sites. The most favorable sorption site in the MOF was identified from the simulations as sorption in the vicinity of a metal-coordinated H2O molecule, an exposed fluorine atom, and a carboxylate oxygen atom in a confined region in the framework. Secondary sorption was observed between the fluorine atoms of adjacent tetrafluoroterephthalate ligands. The H2 molecule at the primary sorption site in [Zn(trz)(tftph)] exhibits a rotational barrier that exceeds that for most neutral MOFs with open-metal sites according to an empirical phenomenological model, and this was further validated by calculating the rotational potential energy surface for H2 at this site.

Tuning the tunneling magnetoresistance by using fluorinated graphene in graphene based magnetic junctions

Directory of Open Access Journals (Sweden)

Shweta Meena

2017-12-01

Full Text Available Spin polarized properties of fluorinated graphene as tunnel barrier with CrO2 as two HMF electrodes are studied using first principle methods based on density functional theory. Fluorinated graphene with different fluorine coverages is explored as tunnel barriers in magnetic tunnel junctions. Density functional computation for different fluorine coverages imply that with increase in fluorine coverages, there is increase in band gap (Eg of graphene, Eg ∼ 3.466 e V was observed when graphene sheet is fluorine adsorbed on both-side with 100% coverage (CF. The results of CF graphene are compared with C4F (fluorination on one-side of graphene sheet with 25% coverage and out-of-plane graphene based magnetic tunnel junctions. On comparison of the results it is observed that CF graphene based structure offers high TMR ∼100%, and the transport of carrier is through tunneling as there are no transmission states near Fermi level. This suggests that graphene sheet with both-side fluorination with 100% coverages acts as a perfect insulator and hence a better barrier to the carriers which is due to negligible spin down current (I↓ in both Parallel Configuration (PC and Antiparallel Configuration (APC.

Nondestructive assay of fluorine in geological and other materials by instrumental photon activation analysis with a microtron

Energy Technology Data Exchange (ETDEWEB)

Krausová, Ivana [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež 130, 25068 Řež (Czech Republic); Mizera, Jiří, E-mail: mizera@ujf.cas.cz [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež 130, 25068 Řež (Czech Republic); Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, V Holešovičkách 41, 182 09 Praha 8 (Czech Republic); Řanda, Zdeněk; Chvátil, David; Krist, Pavel [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež 130, 25068 Řež (Czech Republic)

2015-01-01

Reliable determination of low concentrations of fluorine in geological and coal samples is difficult. It usually requires tedious decomposition and dissolution of the sample followed by chemical conversion of fluorine into its anionic form. The present paper examines possibilities of non-destructive determination of fluorine, mainly in minerals, rocks and coal, by instrumental photon activation analysis (IPAA) using the MT-25 microtron. The fluorine assay consists of counting the positron–electron annihilation line of {sup 18}F at 511 keV, which is a product of the photonuclear reaction {sup 19}F(γ, n){sup 18}F and a pure positron emitter. The assay is complicated by the simultaneous formation of other positron emitters. The main contributors to interference in geological samples are from {sup 45}Ti and {sup 34m}Cl, whereas those from {sup 44}Sc and {sup 89}Zr are minor. Optimizing beam energy and irradiation-decay-counting times, together with using interfering element calibration standards, allowed reliable IPAA determination of fluorine in selected USGS and CRPG geochemical reference materials, NIST coal reference materials, and NIST RM 8414 Bovine Muscle. In agreement with the published data obtained by PIGE, the results of the F assay by IPAA have revealed erroneous reference values provided for the NIST reference materials SRM 1632 Bituminous Coal and RM 8414 Bovine Muscle. The detection limits in rock and coal samples are in the range of 10–100 μg g{sup −1}.

The emission of fluorine gas during incineration of fluoroborate residue

Energy Technology Data Exchange (ETDEWEB)

Feng, Yuheng, E-mail: fengyh@tongji.edu.cn [Thermal & Environmental Engineering Institute, Tongji University, Shanghai 200092 (China); Jiang, Xuguang [State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027 (China); Chen, Dezhen [Thermal & Environmental Engineering Institute, Tongji University, Shanghai 200092 (China)

2016-05-05

Highlights: • Gaseous fluorine products were identified when combusting fluoroborate residue. • BF{sub 3} and SiF{sub 4} tend to be hydrolyzed into HF with the increase of temperature. • The emission of BF{sub 3} and SiF{sub 4} from the chamber could be negligible at 1100 °C. - Abstract: The emission behaviors of wastes from fluorine chemical industry during incineration have raised concerns because multiple fluorine products might danger human health. In this study, fluorine emission from a two-stage incineration system during the combustion of fluoroborate residue was examined. In a TG-FTIR analysis BF{sub 3}, SiF{sub 4} and HF were identified as the initial fluorine forms to be released, while fluorine gases of greenhouse effect such as CF{sub 4} and SF{sub 6} were not found. Below 700 °C, NaBF{sub 4} in the sample decomposed to generate BF{sub 3}. Then part of BF{sub 3} reacted with SiO{sub 2} in the system to form SiF{sub 4} or hydrolyzed to HF. At higher temperatures, the NaF left in the sample was gradually hydrolyzed to form HF. A lab-scale two-stage tube furnace is established to simulate the typical two-stage combustion chamber in China. Experimental tests proved that HF was the only fluorine gas in the flue gas, and emissions of BF{sub 3} and SiF{sub 4} can be negligible. Thermodynamic equilibrium model predicted that all SiF{sub 4} would be hydrolyzed at 1100 °C in the secondary-chamber, which agreed well with the experimental results.

Fluorine determination in diet samples using cyclic NAA and PIGE analysis

International Nuclear Information System (INIS)

Farooqi, A.S.; Arshed, W.; Akanle, O.A.; Spyrou, N.M.

1991-01-01

Fluorine is an important trace element for life and human well-being. Food, in general, provides about 40% of the fluorine intake in the human body. In order to measure fluorine levels in human diet samples, Instrumental Neutron Activation Analysis (INAA) and Proton Induced Gamma-Ray Emission (PIGE) analysis were used. Thermal and epithermal cyclic NAA methods were applied, employing the 19 F(n,γ) 20 F and 19 F(n,p) 19 O nuclear reactions for the determination of fluorine, respectively. Corrections were made for the sodium matrix interference caused by the 23 Na(n,α) 20 F threshold reaction in the case of thermal cyclic NAA and for the oxygen interference via 18 O(n,γ) 19 O reaction when using the epithermal cyclic NAA method. The fluorine contents of diet samples were also determined by PIGE analysis making use of the resonance reaction 19 F(p,αγ) 16 O at 872 KeV. Thermal cyclic NAA was found to be most suitable for the determination of low concentrations of fluorine in the diet samples, with a detection limit of less than 10 μg/g

Synthesis of nanocrystalline fluorinated hydroxyapatite

Indian Academy of Sciences (India)

Fluorinated hydroxyapatite; nanocrystalline; microwave synthesis; dissolution. ... HA by the presence of other ions such as carbonate, magnesium, fluoride, etc. ... Fourier transform infrared spectroscopy (FT–IR) and laser Raman spectroscopy.

Computational rationalization for the observed ground-state multiplicities of fluorinated acylnitrenes.

Science.gov (United States)

Sherman, Matthew P; Jenks, William S

2014-10-03

Computational methods are used to investigate the mechanism by which fluorination of acetylnitrene reduces the stabilization of the singlet configuration. ΔEST is made more positive (favoring the triplet state) by 1.9, 1.3, and 0.7 kcal/mol by the addition of the first, second, and third fluorine, respectively, at the CR-CC(2,3)/6-311(3df,2p)//B3LYP/6-31G(d,p) level of theory. Smaller effects observed with substitution of β-fluorines in propanoylnitrene derivatives and examination of molecular geometries and orbitals demonstrate that the effect is due to inductive electron withdrawal by the fluorines, rather than hyperconjugation.

Strontium and fluorine in tuatua shells

International Nuclear Information System (INIS)

Trompetter, W.J.; Coote, G.E.

1993-01-01

This report describes the research to date on the elemental distributions of strontium, calcium, and fluorine in a collection of 24 tuatua shells (courtesy of National Museum). Variations in elemental concentrations were measured in the shell cross-sections using a scanning proton microprobe (PIXE and PIGME). In this paper we report the findings to date, and present 2-D measurement scans as illustrative grey-scale pictures. Our results support the hypothesis that increased strontium concentrations are deposited in the shells during spawning, and that fluorine concentration is proportional to growth rate. (author). 15 refs.; 13 figs.; 1 appendix

Fluorination of La{sub 2−x}Sr{sub x}CuO{sub 4} (x = 0, 0.15, 0.3) and study on the crystal structures, magnetic properties of their fluorinated products

Energy Technology Data Exchange (ETDEWEB)

Chen, Xiuhua [Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei 230026 (China); Tang, Kaibin, E-mail: kbtang@ustc.edu.cn [Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei 230026 (China); Zeng, Suyuan [Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, Department of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059 (China); Hao, Qiaoyan; Wang, Dake; Gao, Zhan; Wang, Yan [Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, Hefei 230026 (China)

2015-03-25

Highlights: • Fluorination of La{sub 2−x}Sr{sub x}CuO{sub 4} (x = 0, 0.15, 0.3) by ZnF{sub 2} with few byproducts. • Less of impurities are benefit to research its structure and properties. • Suffering a phase transformation and unit cell expansion after fluorination. • Determining chemical formula and fluorine ions occupation of fluorinated product. - Abstract: Here we report using the transition metal difluoride ZnF{sub 2} to fluorinate K{sub 2}NiF{sub 4}-type cuprates La{sub 2−x}Sr{sub x}CuO{sub 4} (x = 0, 1.5, 0.3). Unlike other fluorinating agents, the technique is nontoxic, easy to handle and the byproduct ZnO can be removed. After fluorination, the fluorinated product of La{sub 2}CuO{sub 4} suffers a phase transformation and unit cell expansion. While La{sub 1.85}Sr{sub 0.15}CuO{sub 4} and La{sub 1.7}Sr{sub 0.3}CuO{sub 4} indicate no change in structure after fluorination, their space groups still are I/4mmm, however, their lattices become larger, too. We emphasis the structural characterizations for fluorinated product of La{sub 1.7}Sr{sub 0.3}CuO{sub 4} by high-resolution transmission electron microscopy (HRTEM) images and electron diffraction (ED) patterns. Moreover, we determine the chemical formula to be La{sub 1.54}Sr{sub 0.46}CuO{sub 3.1}F{sub 0.9} and the fluorine ions are prone to be located in the apical sites of the Cu(O, F){sub 6} octahedron in the structure of post-treated fluorinated product of La{sub 1.7}Sr{sub 0.3}CuO{sub 4}. Magnetization investigations demonstrate that partial replacement of the lanthanum by strontium changes the magnetism of post-treated fluorinated products of La{sub 2−x}Sr{sub x}CuO{sub 4} (x = 0, 0.15, 0.3) and they exhibit a paramagnetic behavior.

The impact of dissolved fluorine on bubble nucleation in hydrous rhyolite melts

Science.gov (United States)

Gardner, James E.; Hajimirza, Sahand; Webster, James D.; Gonnermann, Helge M.

2018-04-01

Surface tension of hydrous rhyolitic melt is high enough that large degrees of supersaturation are needed to homogeneously nucleate H2O bubbles during eruptive magma ascent. This study examines whether dissolved fluorine lowers surface tension of hydrous rhyolite, and thus lowers the supersaturation required for bubble nucleation. Fluorine was targeted because it, like H2O, changes melt properties and is highly soluble, unlike all other common magmatic volatiles. Rhyolite melts were saturated at Ps = 245 MPa with H2O fluid that contained F, generating rhyolite with 6.7 ± 0.4 wt.% H2O and 1.1-1.3 wt.% F. When these melts were decompressed rapidly to Pf = 149-202 MPa and quenched after 60 s, bubbles nucleated at supersaturations of ΔP = Ps - Pf ≥52 MPa, and reached bubble number densities of NB = 1012-13 m-3 at ΔP = 78-101 MPa. In comparison, rhyolite saturated with 6.34 ± 0.09 wt.% H2O, but only 0.25 wt.% F, did not nucleate bubbles until ΔP ≥ 100-116 MPa, and even then, at significantly lower NB (<1010 m-3). Numerical modeling of bubble nucleation and growth was used to estimate the values of surface tension required to generate the observed values of NB. Slight differences in melt compositions (i.e., alkalinity and H2O content), H2O diffusivity, or melt viscosity cannot explain the observed differences in NB. Instead, surface tension of F-rich rhyolite must be lower by approximately 4% than that of F-poor rhyolite. This difference in surface tension is significant and, for example, exceeds that found between hydrous basaltic andesite and hydrous rhyolite. These results suggest that is likely that surface tension for F-rich magmas, such as topaz rhyolite, is significantly lower than for F-poor magmas.

Enhanced Light Absorption in Fluorinated Ternary Small-Molecule Photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Eastham, Nicholas D. [Department; Dudnik, Alexander S. [Department; Harutyunyan, Boris [Department; Aldrich, Thomas J. [Department; Leonardi, Matthew J. [Department; Manley, Eric F. [Department; Chemical; Butler, Melanie R. [Department; Harschneck, Tobias [Department; Ratner, Mark A. [Department; Chen, Lin X. [Department; Chemical; Bedzyk, Michael J. [Department; Department; Melkonyan, Ferdinand S. [Department; Facchetti, Antonio [Department; Chang, Robert P. H. [Department; Marks, Tobin J. [Department; Department

2017-06-14

Using small-molecule donor (SMD) semiconductors in organic photovoltaics (OPVs) has historically afforded lower power conversion efficiencies (PCEs) than their polymeric counterparts. The PCE difference is attributed to shorter conjugated backbones, resulting in reduced intermolecular interactions. Here, a new pair of SMDs is synthesized based on the diketopyrrolopyrrole-benzodithiophene-diketopyrrolopyrrole (BDT-DPP2) skeleton but having fluorinated and fluorinefree aromatic side-chain substituents. Ternary OPVs having varied ratios of the two SMDs with PC61BM as the acceptor exhibit tunable open-circuit voltages (Vocs) between 0.833 and 0.944 V due to a fluorination-induced shift in energy levels and the electronic “alloy” formed from the miscibility of the two SMDs. A 15% increase in PCE is observed at the optimal ternary SMD ratio, with the short-circuit current density (Jsc) significantly increased to 9.18 mA/cm2. The origin of Jsc enhancement is analyzed via charge generation, transport, and diffuse reflectance measurements, and is attributed to increased optical absorption arising from a maximum in film crystallinity at this SMD ratio, observed by grazing incidence wide-angle X-ray scattering.

Role of contaminants in the fluorination of β-UO3 to UF4 by freon-12

International Nuclear Information System (INIS)

Girgis, B.S.; Rofail, N.H.

1992-01-01

Ammonium uranate was precipitated from uranyl nitrate or sulphate by NH 3 gas or urea, and decomposed to β-UO 3 by calcination at 623 or 773 K. Oxides contaminated by high contents of nitrates (non-washed uranate) displayed higher conversion to UF 4 in comparison to the respective pre-washed uranate. Products of thermal treatment at 623 K were also more reactive towards fluorination, which was ascribed to the highly-disordered, loosely bound, high surface area products. The presence of residual nitrate, and probably ammonium, ions help in the partial reduction to lower oxides and in preventing recrystallization of the reaction solids. Ammonium uranate precipitated from uranyl sulphate and decomposed at 623 K is more easily fluorinated than the product decomposed at 773 K; it is also better product for fluorination than the uranate precipitated from uranyl nitrate. The complete conversion to UF 4 i attained after 45 min with the uranate precipitated from uranyl sulphate and treated at 623 K, but it needs 120 min with the product formed from uranyl nitrate and decomposed at the same temperature. (orig.)

Surface modification effects of fluorine-doped tin dioxide by oxygen plasma ion implantation

Science.gov (United States)

Tang, Peng; Liu, Cai; Zhang, Jingquan; Wu, Lili; Li, Wei; Feng, Lianghuan; Zeng, Guanggen; Wang, Wenwu

2018-04-01

SnO2:F (FTO), as a kind of transparent conductive oxide (TCO), exhibits excellent transmittance and conductivity and is widely used as transparency electrodes in solar cells. It's very important to modifying the surface of FTO for it plays a critical role in CdTe solar cells. In this study, modifying effects of oxygen plasma on FTO was investigated systematically. Oxygen plasma treatment on FTO surface with ion accelerating voltage ranged from 0.4 kV to 1.6 kV has been processed. The O proportion of surface was increased after ion implantation. The Fermi level of surface measurement by XPS valance band spectra was lowered as the ion accelerating voltage increased to 1.2 kV and then raised as accelerating voltage was elevated to 1.6 kV. The work function measured by Kelvin probe force microscopy increased after ion implanting, and it was consistent with the variation of Fermi level. The change of energy band structure of FTO surface mainly originated from the surface composition variation. As FTO conduction was primarily due to oxyanion hole, the carrier was electron and its concentration was reduced while O proportion was elevated at the surface of FTO, as a result, the Fermi level lowered and the work function was enlarged. It was proved that oxygen plasma treatment is an effective method to modulate the energy band structure of the surface as well as other properties of FTO, which provides much more space for interface and surface modification and then photoelectric device performance promotion.

Anisotropic Copoly(Imide Oxetane) Coatings and Articles of Manufacture, Copoly(Imide Oxetane)s Containing Pendant Fluorocarbon Moieties, Oligomers and Processes Therefor

Science.gov (United States)

Wohl, Christopher J. (Inventor); Connell, John W. (Inventor); Siochi, Emilie J. (Inventor); Smith, Joseph G. (Inventor)

2017-01-01

Copoly(imide oxetane) materials are disclosed that can exhibit a low surface energy while possessing the mechanical, thermal, chemical and optical properties associated with polyimides. The copoly(imide oxetane)s are prepared using a minor amount of fluorinated oxetane-derived oligomer with sufficient fluorine-containing segments of the copoly(imide oxetane)s that migrate to the exterior surface of the polymeric material to yield low surface energies. Thus the coatings and articles of manufacture made with the copoly(imide oxetane)s of this invention are characterized as having an anisotropic fluorine composition. The low surface energies can be achieved with very low content of fluorinated oxetane-derived oligomer. The copolymers of this invention can enhance the viability of polyimides for many applications and may be acceptable where homopolyimide materials have been unacceptable.

Chemical Makeup and Hydrophilic Behavior of Graphene Oxide Nanoribbons after Low-Temperature Fluorination.

Science.gov (United States)

Romero Aburto, Rebeca; Alemany, Lawrence B; Weldeghiorghis, Thomas K; Ozden, Sehmus; Peng, Zhiwei; Lherbier, Aurélien; Botello Méndez, Andrés Rafael; Tiwary, Chandra Sekhar; Taha-Tijerina, Jaime; Yan, Zheng; Tabata, Mika; Charlier, Jean-Christophe; Tour, James M; Ajayan, Pulickel M

2015-07-28

Here we investigated the fluorination of graphene oxide nanoribbons (GONRs) using H2 and F2 gases at low temperature, below 200 °C, with the purpose of elucidating their structure and predicting a fluorination mechanism. The importance of this study is the understanding of how fluorine functional groups are incorporated in complex structures, such as GONRs, as a function of temperature. The insight provided herein can potentially help engineer application-oriented materials for several research and industrial sectors. Direct (13)C pulse magic angle spinning (MAS) nuclear magnetic resonance (NMR) confirmed the presence of epoxy, hydroxyl, ester and ketone carbonyl, tertiary alkyl fluorides, as well as graphitic sp(2)-hybridized carbon. Moreover, (19)F-(13)C cross-polarization MAS NMR with (1)H and (19)F decoupling confirmed the presence of secondary alkyl fluoride (CF2) groups in the fluorinated graphene oxide nanoribbon (FGONR) structures fluorinated above 50 °C. First-principles density functional theory calculations gained insight into the atomic arrangement of the most dominant chemical groups. The fluorinated GONRs present atomic fluorine percentages in the range of 6-35. Interestingly, the FGONRs synthesized up to 100 °C, with 6-19% of atomic fluorine, exhibit colloidal similar stability in aqueous environments when compared to GONRs. This colloidal stability is important because it is not common for materials with up to 19% fluorine to have a high degree of hydrophilicity.

Follow-up of fluorine pollution effect on grapevine

Directory of Open Access Journals (Sweden)

Ferjani Ben Abdallah

2004-12-01

By another way, our results seem to show that full mature grapevine leaves may constitute an efficient tool to assess fluorine pollution impact. Berries contamination seems to be affected directly by the factory smoke, there is no endogenous supply. Likewise, by its characteristic necrosis in the leaf boundaries, grapevine may be considered as a bioindicator variety of fluorine pollution which can be used in mapping polluted areas.

Effects of fluorine on crops, soil exoenzyme activities, and earthworms in terrestrial ecosystems.

Science.gov (United States)

Chae, Yooeun; Kim, Dokyung; An, Youn-Joo

2018-04-30

Fluorine can flow into the environment after leakage or spill accidents and these excessive amounts can cause adverse effects on terrestrial ecosystems. Using three media (filter paper, soil, and filter-paper-on-soil), we investigated the toxic effects of fluorine on the germination and growth of crops (barley, mung bean, sorghum, and wheat), on the activities of soil exoenzymes (acid phosphatase, arylsulfatase, fluorescein diacetate hydrolase, and urease) and on the survival, abnormality, and cytotoxicity of Eisenia andrei earthworms. The germination and growth of crops were affected by fluorine as exposure concentration increased. The activities of the four enzymes after 0-, 3-, 10-, and 20-day periods varied as exposure concentration increased. According to in vivo and in vitro earthworm assays, E. andrei mortality, abnormality, and cytotoxicity increased with increasing fluorine concentration. Overall, fluorine significantly affected each tested species in the concentration ranges used in this study. The activities of soil exoenzymes were also affected by soil fluorine concentration, although in an inconsistent manner. Albeit the abnormally high concentrations of fluorine in soil compared to that observed under natural conditions, its toxicity was much restrained possibly due to the adsorption of fluorine on soil particles and its combination with soil cations. Copyright © 2017 Elsevier Inc. All rights reserved.

Fluorine-free preparation of titanium carbide MXene quantum dots with high near-infrared photothermal performances for cancer therapy.

Science.gov (United States)

Yu, Xinghua; Cai, Xingke; Cui, Haodong; Lee, Seung-Wuk; Yu, Xue-Feng; Liu, Bilu

2017-11-23

Titanium carbide MXene quantum dots (QDs) were synthesized using an effective fluorine-free method as a biocompatible and highly efficient nanoagent for photothermal therapy (PTT) applications. In contrast to the traditional, hazardous and time-consuming process of HF pretreatment, our fluorine-free method is safe and simple. More importantly, abundant Al oxoanions were found to be modified on the MXene QD surface by the fluorine-free method, which endowed the QDs with strong and broad absorption in the NIR region. As a result, the as-prepared MXene QDs exhibited an extinction coefficient as large as 52.8 Lg -1 cm -1 at 808 nm and a photothermal conversion efficiency as high as 52.2%. Both the values are among the best reported so far. The as-prepared MXene QDs achieved simultaneous photoacoustic (PA) imaging and the remarkable PTT effect of tumors. Moreover, MXene QDs showed great biocompatibility without causing noticeable toxicity in vitro and in vivo, indicating their high potential for clinical applications.

Fluorine in plants in the areas of Yugoslav aluminum factories

Energy Technology Data Exchange (ETDEWEB)

Ivos, J.; Ciszek, H.; Rezek, A.; Marjanovic, L.

1970-01-01

Distribution of fluorine in the areas around aluminum production facilities was investigated. The plants in areas around the factories did indeed show increased levels of fluorine. Distribution patterns were found to be affected by wind and precipitation patterns.

Curie temperature rising by fluorination for Sm2Fe17

Directory of Open Access Journals (Sweden)

Matahiro Komuro

2013-02-01

Full Text Available Fluorine atoms can be introduced to Sm2Fe17 using XeF2 below 423 K. The resulting fluorinated Sm2Fe17 powders have ferromagnetic phases containing Sm2Fe17FY1(0fluorination. The largest unit cell volume among the rhombohedral Sm2Fe17 compounds is 83.8 nm3, which is 5.8% larger than Sm2Fe17. The rhombohedral Sm2Fe17 with the largest unit cell volume is dissociated above 873 K, and fluorination increases Curie temperature from 403 K for Sm2Fe17 to 675 K. This increase can be explained by the magneto-volume effect.

Investigating H 2 Sorption in a Fluorinated Metal–Organic Framework with Small Pores Through Molecular Simulation and Inelastic Neutron Scattering

KAUST Repository

Forrest, Katherine A.

2015-07-07

© 2015 American Chemical Society. Simulations of H2 sorption were performed in a metal-organic framework (MOF) consisting of Zn²⁺ ions coordinated to 1,2,4-triazole and tetrafluoroterephthalate ligands (denoted [Zn(trz)(tftph)] in this work). The simulated H2 sorption isotherms reported in this work are consistent with the experimental data for the state points considered. The experimental H2 isosteric heat of adsorption (Qst) values for this MOF are approximately 8.0 kJ mol^-1 for the considered loading range, which is in the proximity of those determined from simulation. The experimental inelastic neutron scattering (INS) spectra for H2 in [Zn(trz)(tftph)] reveal at least two peaks that occur at low energies, which corresponds to high barriers to rotation for the respective sites. The most favorable sorption site in the MOF was identified from the simulations as sorption in the vicinity of a metal-coordinated H2O molecule, an exposed fluorine atom, and a carboxylate oxygen atom in a confined region in the framework. Secondary sorption was observed between the fluorine atoms of adjacent tetrafluoroterephthalate ligands. The H2 molecule at the primary sorption site in [Zn(trz)(tftph)] exhibits a rotational barrier that exceeds that for most neutral MOFs with open-metal sites according to an empirical phenomenological model, and this was further validated by calculating the rotational potential energy surface for H2 at this site. (Figure Presented).

On the Effect of Fluorination of 2,1,3-Benzothiadiazole

KAUST Repository

Nielsen, Christian B.

2015-04-22

The 4,7-dithieno-2,1,3-benzothiadiazole (DTBT) moiety and its fluorinated counterpart are important pi-conjugated building blocks in the field of organic electronics. Here we present a combined experimental and theoretical investigation into fundamental properties relating to these two molecular entities and discuss the potential impact on extended π-conjugated materials and their electronic properties. While the fluorinated derivative, in the solid state, packs with a smaller co-facial overlap than DTBT, we report experimental evidence for stronger optical absorption as well as stronger intra- and intermolecular contacts upon fluorination.

On the Effect of Fluorination of 2,1,3-Benzothiadiazole

KAUST Repository

Nielsen, Christian B.; White, Andrew J. P.; McCulloch, Iain

2015-01-01

The 4,7-dithieno-2,1,3-benzothiadiazole (DTBT) moiety and its fluorinated counterpart are important pi-conjugated building blocks in the field of organic electronics. Here we present a combined experimental and theoretical investigation into fundamental properties relating to these two molecular entities and discuss the potential impact on extended π-conjugated materials and their electronic properties. While the fluorinated derivative, in the solid state, packs with a smaller co-facial overlap than DTBT, we report experimental evidence for stronger optical absorption as well as stronger intra- and intermolecular contacts upon fluorination.

Flexible Slippery Surface to Manipulate Droplet Coalescence and Sliding, and Its Practicability in Wind-Resistant Water Collection.

Science.gov (United States)

Wang, Yuanfeng; Qian, Baitai; Lai, Chuilin; Wang, Xiaowen; Ma, Kaikai; Guo, Yujuan; Zhu, Xingli; Fei, Bin; Xin, John H

2017-07-26

A flexible slippery membrane (FSM) with tunable morphology and high elastic deformability has been developed by infusing perfluoropolyether (PFPE) into a fluorinated-copolymer-modified thermoplastic polyurethane (TPU) nanofiberous membrane. To immobilize PFPE in TPU matrix, we synthesized a fluorinated-copolymer poly(DFMA-co-IBOA-co-LMA) with low surface energy, high chemical affinity to PFPE, adequate flexibility, and strong physical adhesion on TPU. Upon external tensile stress, the as-prepared FSM can realize a real-time manipulation of water sliding and coalescence on it. Furthermore, it exhibits the ability to preserve the captured water from being blown away by strong wind, which ensures the water collection efficiency in windy regions.

Improved stability of highly fluorinated phospholipid-based vesicles in the presence of bile salts.

Science.gov (United States)

Gadras, C; Santaella, C; Vierling, P

1999-01-04

The stability of fluorinated phospholipid-based vesicles in terms of detergent-induced release of encapsulated carboxyfluorescein has been evaluated. The fluorinated liposomes are substantially more resistant towards the lytic action of sodium taurocholate than conventional DSPC or even DSPC/CH 1/1 liposomes. Concerning structure/permeability relationships, the larger the fluorination degree of the membrane, the higher the resistance of the fluorinated liposomes to their destruction by the detergent. These results show that fluorinated liposomes have a promising potential as drug carrier and delivery systems for oral administration.

Direct olefination of fluorinated benzothiadiazoles: a new entry to optoelectronic materials.

Science.gov (United States)

Xiao, Yu-Lan; Zhang, Bo; He, Chun-Yang; Zhang, Xingang

2014-04-14

Fluorinated olefin-containing benzothiadiazoles have important applications in optoelectronic materials. Herein, we reported the direct olefination of fluorinated benzothiadiazoles, as catalyzed by palladium. The reaction proceeds under mild reaction conditions and shows high functional-group compatibility. A preliminary study of the properties of the resulting symmetrical and unsymmetrical olefin-containing fluorinated benzothiadiazoles in red-light-emitting dyes has also been conducted. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Depleted uranium processing and fluorine extraction

International Nuclear Information System (INIS)

Laflin, S.T.

2010-01-01

Since the beginning of the nuclear era, there has never been a commercial solution for the large quantities of depleted uranium hexafluoride generated from uranium enrichment. In the United States alone, there is already in excess of 1.6 billion pounds (730 million kilograms) of DUF_6 currently stored. INIS is constructing a commercial uranium processing and fluorine extraction facility. The INIS facility will convert depleted uranium hexafluoride and use it as feed material for the patented Fluorine Extraction Process to produce high purity fluoride gases and anhydrous hydrofluoric acid. The project will provide an environmentally friendly and commercially viable solution for DUF_6 tails management. (author)

Engineered Multifunctional Fluorinated Film Based on Semicontinuous Emulsion Polymerization Using Polymerizable Quaternary Ammonium Emulsifiers

Directory of Open Access Journals (Sweden)

Hongzhu Liu

2018-01-01

Full Text Available Along with society’s progress, high-quality coatings are widely used. Although fluorinated polymers were successfully prepared by semicontinuous emulsion polymerization with surfactants, chlorotrifluoroethylene (CTFE, and acrylate monomers, the optimization collocation of surfactants still has room for improvement. The traditional emulsifiers are physically absorbed onto the surface of latex particles. The latex film generated by latex particles is unstable in water, which limits its application. Herein, a novel series of cationic quaternary ammonium polymerizable surfactant was selected because it can react with CTFE and acrylate monomers and can become a part of the polymers. We also studied the effects of emulsifier type on resultant emulsion properties. In addition, wonderful weatherability, water resistance, and antibacterial and antifouling of the multifunctional fluorinated films were observed, which would open up a bright future for coating industries.

Depth profile analysis of polymerized fluorine compound on photo-resist film with angle-resolved XPS

International Nuclear Information System (INIS)

Iijima, Yoshitoki; Kubota, Toshio; Oinaka, Syuhei

2013-01-01

Angle-resolved XPS (ARXPS) is an observation technique which is very effective in chemical depth analysis method less than photoelectron detected depth. For the analysis of depth profile, several analysis methods have been proposed to calculate the depth profile using the ARXPS method. The present report is the measurements of depth profile of the fluorine in a fluorine-containing photo-resist film using the ARXPS method and the depth profile of concentration have been successfully determined using the ARCtick 1.0 software. It has been observed that thickness of the fluorocarbon enriched surface layer of the photo-resist was 2.7 nm, and so that the convert of the ARXPS data from the angle profile to the depth profile was proved to be useful analysis method for the ultrathin layer depth. (author)

XPS study of Li/Nb ratio in LiNbO{sub 3} crystals. Effect of polarity and mechanical processing on LiNbO{sub 3} surface chemical composition

Energy Technology Data Exchange (ETDEWEB)

Skryleva, E.A., E-mail: easkryleva@gmail.com; Kubasov, I.V., E-mail: kubasov.ilya@gmail.com; Kiryukhantsev-Korneev, Ph.V., E-mail: kiruhancev-korneev@yandex.ru; Senatulin, B.R., E-mail: borisrs@yandex.ru; Zhukov, R.N., E-mail: rom_zhuk@mail.ru; Zakutailov, K.V., E-mail: zakkonst@gmail.com; Malinkovich, M.D., E-mail: malinkovich@yandex.ru; Parkhomenko, Yu.N., E-mail: parkh@rambler.ru

2016-12-15

Highlights: • XPS Li/Nb ratio measurement uncertainty in LNbO3 specimens was obtained. • The effect of polarization on surface chemistry was observed only on cleaves. • Li/Nb ratio on positive cleave surface is higher than on negative one. • The positive cleave surface adsorbs fluorine more efficiently than negative one. • Mechanical processing of crystals reduces surface Li/Nb. - Abstract: Different sections of congruent lithium niobate (CLN) crystals have been studied using X-ray photoelectron spectroscopy (XPS). We have developed a method for measuring the lithium-to-niobium atomic ratio Li/Nb from the ratio of the Li1s and Nb4s spectral integral intensities with an overall error of within 8 %. Polarity and mechanical processing affect the Li/Nb ratio on CLN crystal surfaces. The Li/Nb ratio is within the tolerance (0.946 ± 0.074) on the negative cleave surface Z, and there is excess lithium (Li/Nb = 1.25 ± 0.10) on the positive surface. The positive surfaces of the 128° Y cut plates after long exposure to air exhibit LiOH formation indications (obvious lithium excess, higher Li1s spectral binding energy and a wide additional peak in the O1s spectrum produced by nonstructural oxygen). XPS and glow discharge optical electron spectroscopy showed that mechanical processing of differently oriented crystals (X, Z and 128° Y) and different polarities dramatically reduces the Li/Nb ratio. In situ fluorine adsorption experiments revealed the following regularities: fluorine adsorption only occurred on crystal cleaves and was not observed for mechanically processed specimens. Positive cleave surfaces have substantially higher fluorine adsorption capacity compared to negative ones.

Modification of Surface Energy via Direct Laser Ablative Surface Patterning

Science.gov (United States)

Wohl, Christopher J., Jr. (Inventor); Belcher, Marcus A. (Inventor); Connell, John W. (Inventor); Hopkins, John W. (Inventor)

2015-01-01

Surface energy of a substrate is changed without the need for any template, mask, or additional coating medium applied to the substrate. At least one beam of energy directly ablates a substrate surface to form a predefined topographical pattern at the surface. Each beam of energy has a width of approximately 25 micrometers and an energy of approximately 1-500 microJoules. Features in the topographical pattern have a width of approximately 1-500 micrometers and a height of approximately 1.4-100 micrometers.

[Assessment of Soil Fluorine Pollution in Jinhua Fluorite Ore Areas].

Science.gov (United States)

Ye, Qun-feng; Zhou, Xiao-ling

2015-07-01

The contents of. soil total fluorine (TF) and water-soluble fluorine (WF) were measured in fluorite ore areas located in Jinhua City. The single factor index, geoaccumulation index and health risk assessment were used to evaluate fluorine pollution in soil in four fluorite ore areas and one non-ore area, respectively. The results showed that the TF contents in soils were 28. 36-56 052. 39 mg.kg-1 with an arithmetic mean value of 8 325.90 mg.kg-1, a geometric mean of 1 555. 94 mg.kg-1, and a median of 812. 98 mg.kg-1. The variation coefficient of TF was 172. 07% . The soil WF contents ranged from 0. 83 to 74. 63 mg.kg-1 with an arithmetic mean value of 16. 94 mg.kg-1, a geometric mean of 10. 59 mg.kg-1, and a median of 10. 17 mg.kg-1. The variation coefficient of WF was 100. 10%. The soil TF and WF contents were far higher than the national average level of the local fluorine epidemic occurrence area. The fluoride pollution in soil was significantly affected by human factors. Soil fluorine pollution in Yangjia, Lengshuikeng and Huajie fluorite ore areas was the most serious, followed by Daren fluorite ore area, and in non-ore area there was almost no fluorine pollution. Oral ingestion of soils was the main exposure route. Sensitivity analysis of model parameters showed that children's weight exerted the largest influence over hazard quotient. Furthermore, a significant positive correlation was found among the three kinds of evaluation methods.

Surface energy anisotropy of tungsten

Energy Technology Data Exchange (ETDEWEB)

Kumar, R; Grenga, H E [Georgia Inst. of Tech., Atlanta (USA). School of Chemical Engineering

1976-10-01

Field-ion microscopy was used to study the faceting behavior and/or surface energy anisotropy of tungsten in vacuum and in hydrogen. In vacuum below 1700 K the activation energy for (110) facet growth agreed with values previously reported for surface diffusion on tungsten. The observed anisotropy values at 0.5 Tsub(m), where Tsub(m) is the absolute melting temperature of tungsten (approximately 3680 K), were different from those previously reported at higher temperatures and more nearly agreed with broken bond calculations based on Mie potential using m=5, n=8, and a 1.5% lattice expansion. Hydrogen appeared to have a negligible effect on surface energy anisotropy, but did preferentially increase surface diffusion rates on (310) regions.

Mechanical properties of fluorinated DLC and Si interlayer on a Ti biomedical alloy

International Nuclear Information System (INIS)

Chou, Chau-Chang; Wu, Yi-Yang; Lee, Jyh-Wei; Huang, Jen-Ching; Yeh, Chi-Hsiao

2013-01-01

Fluorinated amorphous diamond-like carbon (F-DLC) films were deposited on Ti6Al4V substrates by radio frequency plasma enhanced chemical vapor deposition (rf PECVD) technique using a mixture of methane (CH 4 ) and tetrafluoromethane (CF 4 ) gasses. A 100 nm Si interlayer was coated in advance by physical vapor deposition (PVD) process to improve the adhesion between F-DLC and Ti alloy. The structure and surface properties of F-DLC coatings, prepared by various fluorine flow ratios, were investigated by using X-ray diffraction spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The mechanical properties were evaluated by nano-indentation, and the adhesion, by micro-scratch. The results showed that a moderate incorporation of the fluorine content in the DLC films can still maintain acceptable mechanical properties, which, on the other hand, obtains remarkable benefits of blood compatibility and anti-corrosion. - Highlights: ► F-DLC’s sp2 carbon cluster increases with the precursors’ CF 4 /CH 4 ratio. ► F-DLC’s reduced elastic modulus and hardness decrease with the CF 4 /CH 4 ratio. ► F-DLC film’s adhesion strength degrades as the CF 4 /CH 4 ratio elevated. ► An F-DLC deposited Ti6Al4V produced by a smaller CF 4 /CH 4 ratio, 1-3, is suggested

Hydrophobic Coatings on Cotton Obtained by in Situ Plasma Polymerization of a Fluorinated Monomer in Ethanol Solutions.

Science.gov (United States)

Molina, Ricardo; Teixidó, Josep Maria; Kan, Chi-Wai; Jovančić, Petar

2017-02-15

Plasma polymerization using hydrophobic monomers in the gas phase is a well-known technology to generate hydrophobic coatings. However, synthesis of functional hydrophobic coatings using plasma technology in liquids has not yet been accomplished. This work is consequently focused on polymerization of a liquid fluorinated monomer on cotton fabric initiated by atmospheric plasma in a dielectric barrier discharge configuration. Functional hydrophobic coatings on cotton were successfully achieved using in situ atmospheric plasma-initiated polymerization of fluorinated monomer dissolved in ethanol. Gravimetric measurements reveal that the amount of polymer deposited on cotton substrates can be modulated with the concentration of monomer in ethanol solution, and cross-linking reactions occur during plasma polymerization of a fluorinated monomer even without the presence of a cross-linking agent. FTIR and XPS analysis were used to study the chemical composition of hydrophobic coatings and to get insights into the physicochemical processes involved in plasma treatment. SEM analysis reveals that at high monomer concentration, coatings possess a three-dimensional pattern with a characteristic interconnected porous network structure. EDX analysis reveals that plasma polymerization of fluorinated monomers takes place preferentially at the surface of cotton fabric and negligible polymerization takes place inside the cotton fabric. Wetting time measurements confirm the hydrophobicity of cotton coatings obtained although equilibrium moisture content was slightly decreased. Additionally, the abrasion behavior and resistance to washing of plasma-coated cotton has been evaluated.

Exploration of fluorine chemistry at the multidisciplinary interface of chemistry and biology.

Science.gov (United States)

Ojima, Iwao

2013-07-05

Over the last three decades, my engagement in "fluorine chemistry" has evolved substantially because of the multidisciplinary nature of the research programs. I began my research career as a synthetic chemist in organometallic chemistry and homogeneous catalysis directed toward organic synthesis. Then, I was brought into a very unique world of "fluorine chemistry" in the end of 1970s. I started exploring the interface of fluorine chemistry and transition metal homogeneous catalysis first, which was followed by amino acids, peptides, and peptidomimetics for medicinal chemistry. Since then, I have been exploring the interfaces of fluorine chemistry and multidisciplinary fields of research involving medicinal chemistry, chemical biology, cancer biology, and molecular imaging. This perspective intends to cover my fruitful endeavor in the exploration of fluorine chemistry at the multidisciplinary interface of chemistry and biology in a chronological order to show the evolution of my research interest and strategy.

Effects of Alternating Hydrogenated and Protonated Segments in polymers on their Wettability.

Science.gov (United States)

Smith, Dennis; Traiphol, Rakchart; Cheng, Gang; Perahia, Dvora

2003-03-01

Polymers consisting of alternating hydrogenated and fluorinated segments exhibit unique interfacial characteristics governed by the components that dominate the interface. Presence of fluorine reduces the interfacial energy and is expected to decrease the adhesion to the polymer surface. Thin liquid crystalline (LC) layers of 4,4?-octyl-cyanobiphenyl, cast on top of a polymeric layer consisting of alternating methylstylbine protonated segments bridged by a fluorinated group was used as a mechanistic tool to study of interfacial effects on three parameters: wetting, interfacial alignment and surface induces structures. The liquid crystal cast on a low interfacial energy fluorinated polymeric film exhibits bulk homeotropic alignment as expected. However it fully wetted the polymer surface despite the incompatibility of the protonated LC and mainly fluorinated polymer interface. Further more, it was found to stabilize the interfacial Semitic layers to a higher temperature and induce different surface ordering that was not observed at the same temperature neither in the bulk nor at the interfaces with silicon or glass surface. These results indicate that the interfacial interactions of polymers with liquid crystals are a complex function of both surface energies and the interfacial structure of the polymer.

Spectrographic determination of chlorine and fluorine

International Nuclear Information System (INIS)

Contamin, G.

1965-04-01

Experimental conditions have been investigated in order to obtain the highest sensitivity in spectrographic determination of chlorine and fluorine using the Fassel method of excitation in an inert atmosphere. The influence of the nature of the atmosphere, of the discharge conditions and of the matrix material has been investigated. The following results have been established: 1. chlorine determination is definitely possible: a working curve has been drawn between 10 μg and 100 μg, the detection limit being around 5 μg; 2. fluorine determination is not satisfactory: the detection limit is still of the order of 80 μg. The best operating conditions have been defined for both elements. (author) [fr

Corrosion-Mitigating, Bondable, Fluorinated Barrier Coating for Anodized Magnesium

Science.gov (United States)

2016-05-01

ARL-TR-7669 ● MAY 2016 US Army Research Laboratory Corrosion -Mitigating, Bondable, Fluorinated Barrier Coating for Anodized...ARL-TR-7669 ● MAY 2016 US Army Research Laboratory Corrosion -Mitigating, Bondable, Fluorinated Barrier Coating for Anodized...TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) May 2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) January–December 2015 4. TITLE

Mutasynthesis of fluorinated pactamycin analogues and their antimalarial activity.

Science.gov (United States)

Almabruk, Khaled H; Lu, Wanli; Li, Yuexin; Abugreen, Mostafa; Kelly, Jane X; Mahmud, Taifo

2013-04-05

A mutasynthetic strategy has been used to generate fluorinated TM-025 and TM-026, two biosynthetically engineered pactamycin analogues produced by Streptomyces pactum ATCC 27456. The fluorinated compounds maintain excellent activity and selectivity toward chloroquine-sensitive and multidrug-resistant strains of malarial parasites as the parent compounds. The results also provide insights into the biosynthesis of 3-aminobenzoic acid in S. pactum.

Enhanced optical limiting effect in fluorine-functionalized graphene oxide

Science.gov (United States)

Zhang, Fang; Wang, Zhengping; Wang, Duanliang; Wang, Shenglai; Xu, Xinguang

2017-09-01

Nonlinear optical absorption of fluorine-functionalized graphene oxide (F-GO) solution was researched by the open-aperture Z-scan method using 1064 and 532 nm lasers as the excitation sources. The F-GO dispersion exhibited strong optical limiting property and the fitted results demonstrated that the optical limiting behavior was the result of a two-photon absorption process. For F-GO nanosheets, the two-photon absorption coefficients at 1064 nm excitation are 20% larger than the values at 532 nm excitation and four times larger than that of pure GO nanosheets. It indicates that the doping of fluorine can effectively improve the nonlinear optical property of GO especially in infrared waveband, and fluorine-functionalized graphene oxide is an excellent nonlinear absorption material in infrared waveband.

Surface energy of metal alloy nanoparticles

Science.gov (United States)

Takrori, Fahed M.; Ayyad, Ahmed

2017-04-01

The measurement of surface energy of alloy nanoparticles experimentally is still a challenge therefore theoretical work is necessary to estimate its value. In continuation of our previous work on the calculation of the surface energy of pure metallic nanoparticles we have extended our work to calculate the surface energy of different alloy systems, namely, Co-Ni, Au-Cu, Cu-Al, Cu-Mg and Mo-Cs binary alloys. It is shown that the surface energy of metallic binary alloy decreases with decreasing particle size approaching relatively small values at small sizes. When both metals in the alloy obey the Hume-Rothery rules, the difference in the surface energy is small at the macroscopic as well as in the nano-scale. However when the alloy deviated from these rules the difference in surface energy is large in the macroscopic and in the nano scales. Interestingly when solid solution formation is not possible at the macroscopic scale according to the Hume-Rothery rules, it is shown it may form at the nano-scale. To our knowledge these findings here are presented for the first time and is challenging from fundamental as well as technological point of views.

Fluorine Abundances in AGB Carbon Stars: New Results?

Science.gov (United States)

Abia, C.; de Laverny, P.; Recio-Blanco, A.; Domínguez, I.; Cristallo, S.; Straniero, O.

2009-09-01

A recent reanalysis of the fluorine abundance in three Galactic Asymptotic Giant Branch (AGB) carbon stars (TX Psc, AQ Sgr and R Scl) by Abia et al. (2009) results in estimates of fluorine abundances systematically lower by ~0.8 dex on average, with respect to the sole previous estimates by Jorissen, Smith & Lambert (1992). The new F abundances are in better agreement with the predictions of full-network stellar models of low-mass (<3 Msolar) AGB stars.

Enhanced electrokinetic remediation of fluorine-contaminated soil by applying an ammonia continuous circulation system

Energy Technology Data Exchange (ETDEWEB)

Zhu, Shufa; Zhou, Ming; Zhang, Shuangyan [Henan University of Science and Technology, Luoyang (China)

2016-02-15

The objective of this research was to investigate the effects of ammonia continuous circulation enhanced electrokinetic remediation of fluorine contaminated soil and to analyze its influence on soil pH after remediation. An experimental study was carried out in self-made electrokinetic apparatus. The voltage gradient was set at 1.0V/cm and ammonia water with different concentrations was used as electrolyte which circulated in series. Comparative studies were made by using deionized water as electrolyte which circulated separately in one experiment and continuously in another. According to the experiment the continuous circulation of ammonia water increased the current value during the remediation process and maintained current through the soil cell stabler, which not only increased fluorine migration but also reduced energy consumption. Among the given ammonia concentrations (0, 0.01, 0.1 and 0.2mol/L) the removal rate increased with ammonia concentration. 0.2mol/L had the highest current (26.8mA), and the removal rate amounted up to 57.3%. By using ammonia circulation enhanced electrokinetic technology, the difference between pH values of cathode soil and anode soil became smaller. Ammonia continuous circulation enhanced electrokinetics can effectively remediate fluorine contaminated soil and the residual ammonia in the soil can also improve soil fertility.

Determination of fluorine in aqueous solution by means of photon activation

International Nuclear Information System (INIS)

Engelmann, Ch.; Gosset, J.

1982-01-01

An apparatus ensuring identical irradiation conditions for three samples and a standard of large volumes is reported. The interference caused by the protons originating from the 16 O(γ,p) 15 N reaction is determined. Results show that the secondary reaction 18 O(p,n) 18 F induced by the protons of the former reaction gives an apparent fluorine content in natural waters of 0.015 μg/g for a maximum gamma photon beam energy of 21 MeV. (author)

Determination of fluorine trace amounts in metallic uranium

Energy Technology Data Exchange (ETDEWEB)

Kukisheva, T N; Bolshakova, A S; Yefimova, N S

1976-05-01

A simple and rapid method was proposed for the determination of fluorine in metallic uranium without the removal of the latter. The method is based on the weakening of the color intensity of a complex of zirconium with xylenol orange in the presence of fluorine in a 1 N solution with respect to hydrochloric acid. For preparation for photometry, the solution to be analyzed is neutralized with ammonia to a pH of approximately 3. It is suggested that a complex of sulfosalicylic acid with uranium (VI) be used as the indicator in neutralization. The required acidity in the solution subjected to photometry is provided by the addition of a 5 N hydrochloric acid solution of zirconium. The coefficient of variation V/sub 15/ (at a fluorine content 3x10/sup -3/%) is 10%. In 7 h, 15-20 determinations can be performed.

Self-assembly and omniphobic property of fluorinated unit end-functionalized poly(methyl methacrylate)

Science.gov (United States)

Junyan, Liang; Pingdi, Xu; Jingxian, Bao; Ling, He; Nan, Zhu

2018-03-01

The self-assembly behavior of fluorinated unit end-functionalized poly(methyl methacrylate) (PDFHM-ef-PMMA) in solution and its influence on the surface microstructure, elemental composition and omniphobic property of cast film was investigated in this work. Specifically, three mixed solutions of tetrahydrofuran (THF)/methanol (MeOH), THF/H2O and THF/H2O/MeOH in various compositions were employed separately as the selective solvents. In THF/MeOH solution, the aggregate morphologies of PDFHM-ef-PMMA changed gradually from core-shell spheres to worm, and then to elliptical vesicles as MeOH content increased. In THF/H2O solution, spherical and bowl-shaped aggregates with significantly larger sizes than those in THF/MeOH solution were favored despite lower H2O content. The further addition of MeOH to THF/H2O mixture could reduce the size of aggregate but hardly change original aggregate morphology. During the film formation process, those self-assembled aggregates in THF/MeOH solution fused with one another to form a smooth surface. When such surface was fully covered by fluorinated segments, the outstanding hexadecane and water slide-off properties and ink-resistant property required for antifouling application were demonstrated. Instead, the aggregates formed in THF/H2O/MeOH mixture were subjected to secondary aggregation of PDFHM-ef-PMMA chains during solvent evaporation, leading to the formation of a particulate film with poor adhesion towards glass plate and hexadecane-repellent property.

Material transfer mechanisms between aluminum and fluorinated carbon interfaces

Energy Technology Data Exchange (ETDEWEB)

Sen, F.G. [NSERC/General Motors of Canada Industrial Research Chair, Department of Mechanical, Automotive and Materials Engineering, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4 (Canada); Qi, Y. [Chemical Sciences and Materials Systems Laboratory, General Motors R and D Center, 30500 Mound Road, Warren, MI 48090-9055 (United States); Alpas, A.T., E-mail: aalpas@uwindsor.ca [NSERC/General Motors of Canada Industrial Research Chair, Department of Mechanical, Automotive and Materials Engineering, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4 (Canada)

2011-04-15

First-principles calculations and sliding contact experiments were conducted to elucidate material transfer mechanisms between aluminum and fluorinated carbon (diamond, diamond-like carbon (DLC)) surfaces. An interface model that examined interactions between Al (1 1 1) and F-terminated diamond (1 1 1) surfaces revealed that F atoms would transfer to the Al surface in increasing quantities with an increase in the contact pressure, and this F transfer would lead to the formation of a stable AlF{sub 3} compound at the Al surface. The presence of AlF{sub 3} on the transfer layers formed at the Al counterface placed in sliding contact against DLC containing 3 at.% F was confirmed by both X-ray photoelectron spectroscopy and cross-sectional focussed-ion beam transmission electron microscopy analyses. The coefficient of friction (COF) of the DLC coating was high initially due to deformation and wear of Al counterface, but formation of -OH and -H passivated C-rich transfer layers on Al reduced the COF to a low steady-state value of 0.20. The repulsive forces generated between the two F-passivated surfaces further decreased the COF to 0.14.

Material transfer mechanisms between aluminum and fluorinated carbon interfaces

International Nuclear Information System (INIS)

Sen, F.G.; Qi, Y.; Alpas, A.T.

2011-01-01

First-principles calculations and sliding contact experiments were conducted to elucidate material transfer mechanisms between aluminum and fluorinated carbon (diamond, diamond-like carbon (DLC)) surfaces. An interface model that examined interactions between Al (1 1 1) and F-terminated diamond (1 1 1) surfaces revealed that F atoms would transfer to the Al surface in increasing quantities with an increase in the contact pressure, and this F transfer would lead to the formation of a stable AlF 3 compound at the Al surface. The presence of AlF 3 on the transfer layers formed at the Al counterface placed in sliding contact against DLC containing 3 at.% F was confirmed by both X-ray photoelectron spectroscopy and cross-sectional focussed-ion beam transmission electron microscopy analyses. The coefficient of friction (COF) of the DLC coating was high initially due to deformation and wear of Al counterface, but formation of -OH and -H passivated C-rich transfer layers on Al reduced the COF to a low steady-state value of 0.20. The repulsive forces generated between the two F-passivated surfaces further decreased the COF to 0.14.

Influence of Backbone Fluorination in Regioregular Poly(3-alkyl-4-fluoro)thiophenes

KAUST Repository

Fei, Zhuping

2015-06-03

© 2015 American Chemical Society. We report two strategies toward the synthesis of 3-alkyl-4-fluorothiophenes containing straight (hexyl and octyl) and branched (2-ethylhexyl) alkyl groups. We demonstrate that treatment of the dibrominated monomer with 1 equiv of alkyl Grignard reagent leads to the formation of a single regioisomer as a result of the pronounced directing effect of the fluorine group. Polymerization of the resulting species affords highly regioregular poly(3-alkyl-4-fluoro)thiophenes. Comparison of their properties to those of the analogous non-fluorinated polymers shows that backbone fluorination leads to an increase in the polymer ionization potential without a significant change in optical band gap. Fluorination also results in an enhanced tendency to aggregate in solution, which is ascribed to a more co-planar backbone on the basis of Raman and DFT calculations. Average charge carrier mobilities in field-effect transistors are found to increase by up to a factor of 5 for the fluorinated polymers.

Fluorine follows water: Effect on electrical conductivity of silicate minerals by experimental constraints from phlogopite

Science.gov (United States)

Li, Yan; Jiang, Haotian; Yang, Xiaozhi

2017-11-01

Fluorine and hydroxyl groups are minor constituents of silicate minerals, and share a lot of similarities concerning their physical and chemical properties. Hydroxyl groups significantly enhance the electrical conductivity of many silicate minerals, and it is expected that fluorine would have a comparable effect. This, however, has never been documented quantitatively. Here we present experimental approaches on this issue, by investigating the electrical conductivity of phlogopite with a wide range of fluorine content (but with broadly similar contents for other major elements). Electrical conductivities of gem-quality single crystal phlogopites, with samples prepared along the same orientation (normal to the (0 0 1) plane), were determined at 1 GPa and 200-650 °C using an end-loaded piston cylinder apparatus and a Solartron-1260 Impedance/Gain Phase Analyzer over the frequency range of 106 to 0.1 Hz. The complex spectra usually show an arc in the high frequency range and a short tail in the low frequency range, which are caused by lattice conduction and electrode effects, respectively. The electrical conductivity increases with increasing fluorine content, and the main charge carriers are fluorine. The activation enthalpies are ∼180 to 200 kJ/mol, nearly independent of fluorine content. The conductivity is linearly proportional to the content of fluorine, with an exponent factor of ∼1. The results demonstrate that conduction by fluorine leads to very high electrical conductivity at high temperatures. The influence of fluorine on electrical conductivity may be compared to that of hydrogen in nominally anhydrous minerals. This, along with the close association of fluorine and hydroxyl groups in silicate minerals and their similar crystal-chemical behaviors, suggests a more general role of fluorine in enhancing the electrical conductivity of many silicate minerals. Fluorine-rich assemblages, e.g., phlogopite and amphibole, could be locally enriched in the upper

Thermogravimetric study of the reaction of uranium oxides with fluorine

International Nuclear Information System (INIS)

Komura, Motohiro; Sato, Nobuaki; Kirishima, Akira; Tochiyama, Osamu

2008-01-01

Thermogravimetric study of the reaction of uranium oxides with fluorine was conducted by TG-DTA method using anti-corrosion type differential thermobalance. When UO 2 was heated from R.T. to 500 deg. C in 5% F 2 /He atmosphere, the weight increase appeared at ca. 250 deg. C with an exothermic peak. Then the weight decreased slightly with a small exothermic peak followed by the complete volatilization with a large exothermic peak at ca. 350 deg. C. At a flow rate of 15, 30, 60 ml min -1 , there seemed to be no significant change for the fluorination of UO 2 . With the different heating rates of 1, 2, 5 and 10 deg. C min -1 , the fluorination peak shifted to higher temperature with increasing heating rates. For the comparison with thermogravimetric results, phase analysis by XRD method was conducted for the products obtained at different temperatures. At 260 deg. C, the product was UO 2 with a small amount of the intermediate compound, UO 2 F. The amount of this compound increased with increasing temperature up to 320 deg. C. Then another phase of UO 2 F 2 appeared at 340 deg. C but it was immediately fluorinated to the volatile fluoride. When U 3 O 8 was used as a starting material, it was found that the steep weight decrease peak appeared at ca. 350 deg. C and the uranium volatilized completely. This result suggests that fluorination of U 3 O 8 occurs at this temperature forming UF 6 . Uranium trioxide showed the similar fluorination behavior to that of U 3 O 8

Molten Fluoride Salts as Fluorine Source in the Production of Molecular Sidebands

CERN Document Server

Shoaib, Maryam

2015-01-01

The medically important isotopes Yttrium and Zirconium were selected for fluorination. After this, 30 $\\mu$g of NaF as fluorine source was put in mass marker in the target unit. It was heated and plasma ion source was used to ionize the vapors. The ion source efficiency was 27\\%. It was observed that the yield for fluorine was not enough for various mass marker temperatures (0 A - 40 A) and ion source temperatures (2000 $^{o}$C - 2150$^{o}$C) to be reacted with other elements. The optimum temperatures of mass marker was observed here as 35 A. The project can be proceeded for further high temperatures and for different fluorine sources.

Structural evolution of fluorinated graphene upon molten-alkali treatment probed by X-ray absorption near-edge structure spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Liang, Xianqing, E-mail: lxq@gxu.edu.cn [Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology, College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Pan, Deyou; Lao, Ming; Liang, Shuiying [Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology, College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Huang, Dan; Zhou, Wenzheng; Guo, Jin [Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology, College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

2017-05-15

Highlights: • Structural evolution of FG during the molten-alkali treatment was studied. • XANES results reveal the transformation of surface functional groups of HFG. • The local and electronic structure of HFG can be tuned by varying the alkali-FG ratio. - Abstract: The structural evolution of fluorinated graphene (FG) nanosheets upon molten-alkali treatment has been systematically investigated utilizing X-ray absorption near-edge structure (XANES) spectroscopy. It is found that the hydroxyl groups can progressively displace fluorine atoms to form covalent bonds to the graphene sheets under designed molten-alkali condition. The XANES spectra also reveal the formation of epoxide groups through intramolecular dehydration of neighbouring hydroxyl groups after substitution reaction. At high alkali-FG weight ratio, the restoration of the π-conjugated structure in graphene sheets can be observed due to the gradual decomposition of epoxide groups. Our experimental results indicate that the surface chemistry and electronic structure of hydroxyl-functionalized FG (HFG) can be readily tuned by varying the ratio of reactants.

Aliphatic Nucleophilic Radio-fluorination

International Nuclear Information System (INIS)

Roeda, D.; Dolle, F.

2010-01-01

In this review we are looking at some aspects of nucleophilic aliphatic radio-fluorination, notably the labelled fluoride source, design aspects, the leaving group and the solvent. It should be clear that there is more to this branch of radiolabelling than one would suspect from the frequently used standard tosylate replacement with kryptofix/[ 18 F]fluoride in acetonitrile or DMSO. Competitive elimination can be a serious problem that can affect both yield and purification. De-protection of sensitive groups after radiolabelling and its possible side reactions can complicate purification. The right choice of leaving group and protecting groups may be crucial. Newer developments such as the use of tertiary alcohols or ionic liquids as solvents, long-chain poly-fluorinated sulphonate leaving groups facilitating fluorous solid phase extraction, or immobilisation of the precursor on a solid phase support may help to solve these problems, for example the longstanding problems with [ 18 F]FLT, whereas older concepts such as certain cyclic reactive entities for ring opening or even an abandoned reagent as [ 18 F]DAST should not be forgotten. (authors)

Reduced chemical warfare agent sorption in polyurethane-painted surfaces via plasma-enhanced chemical vapor deposition of perfluoroalkanes.

Science.gov (United States)

Gordon, Wesley O; Peterson, Gregory W; Durke, Erin M

2015-04-01

Perfluoralkalation via plasma chemical vapor deposition has been used to improve hydrophobicity of surfaces. We have investigated this technique to improve the resistance of commercial polyurethane coatings to chemicals, such as chemical warfare agents. The reported results indicate the surface treatment minimizes the spread of agent droplets and the sorption of agent into the coating. The improvement in resistance is likely due to reduction of the coating's surface free energy via fluorine incorporation, but may also have contributing effects from surface morphology changes. The data indicates that plasma-based surface modifications may have utility in improving chemical resistance of commercial coatings.

SURFACE SYMMETRY ENERGY OF NUCLEAR ENERGY DENSITY FUNCTIONALS

Energy Technology Data Exchange (ETDEWEB)

Nikolov, N; Schunck, N; Nazarewicz, W; Bender, M; Pei, J

2010-12-20

We study the bulk deformation properties of the Skyrme nuclear energy density functionals. Following simple arguments based on the leptodermous expansion and liquid drop model, we apply the nuclear density functional theory to assess the role of the surface symmetry energy in nuclei. To this end, we validate the commonly used functional parametrizations against the data on excitation energies of superdeformed band-heads in Hg and Pb isotopes, and fission isomers in actinide nuclei. After subtracting shell effects, the results of our self-consistent calculations are consistent with macroscopic arguments and indicate that experimental data on strongly deformed configurations in neutron-rich nuclei are essential for optimizing future nuclear energy density functionals. The resulting survey provides a useful benchmark for further theoretical improvements. Unlike in nuclei close to the stability valley, whose macroscopic deformability hangs on the balance of surface and Coulomb terms, the deformability of neutron-rich nuclei strongly depends on the surface-symmetry energy; hence, its proper determination is crucial for the stability of deformed phases of the neutron-rich matter and description of fission rates for r-process nucleosynthesis.

Leaching of lava and tephra from the Oldoinyo Lengai volcano (Tanzania): Remobilization of fluorine and other potentially toxic elements into surface waters of the Gregory Rift

Science.gov (United States)

Bosshard-Stadlin, Sonja A.; Mattsson, Hannes B.; Stewart, Carol; Reusser, Eric

2017-02-01

Volcanic ash leachate studies have been conducted on various volcanoes on Earth, but few have been done on African volcanoes until now. Tephra emissions may affect the environment and the health of people living in this area, and therefore we conducted a first tephra (ash and lapilli sized) leachate study on the Oldoinyo Lengai volcano, situated in northern Tanzania. The recent explosive eruption in 2007-2008 provided us with fresh samples from the first three weeks of the eruption which were used for this study. In addition, we also used a natrocarbonatitic sample from the activity prior to the explosive eruption, as the major activity at Oldoinyo Lengai is natrocarbonatitic. To compare the leaching process affecting the natrocarbonatitic lavas and the tephras from Oldoinyo Lengai, the 2006 natrocarbonatitic lava flow was resampled 5 years after the emplacement and compared to the initial, unaltered composition. Special interest was given to the element fluorine (F), since it is potentially toxic to both humans and animals. A daily intake of fluoride (F-) in drinking water of > 1.5 mg/l can lead to dental fluorosis, and higher concentrations lead to skeletal fluorosis. For this reason, a guideline value for fluoride in drinking water was set by the WHO (2011) to 1.5 mg/l. However, surface waters and groundwaters in the Gregory Rift have elevated fluoride levels of up to 9.12 mg/l, and as a consequence, an interim guideline value for Tanzania has been set at 8 mg/l. The total concentration of fluorine in the samples from the natrocarbonatitic lava flow is high (3.2 wt%), whereas we observed a significant decrease of the fluorine concentration (between 1.7 and 0.5 wt%) in the samples collected three days and three weeks after the onset of the explosive 2007-08 eruption. However, the total amount of water-extractable fluoride is lower in the natrocarbonatitic lavas (319 mg/l) than in the nephelinitic tephra (573-895 mg/l). This is due to the solubility of the

Fluorine emissions of industrial origin. Effect of fluorine on plants and animals

Energy Technology Data Exchange (ETDEWEB)

Cristiani, H

1927-05-01

Shrinkage and drooping of cress plants and grass, and lesions in dandelion leaves, caused by a 1-hr exposure to fluorine vapors in a test chamber are described. In the vicinity of an aluminum plant, where the electrolyte bath is composed of cryolite, a sodium aluminum fluoride, vegetables and the leaves of fruit trees show signs of burning and great damage can be observed on forest trees. Animals are affected by fluoride through their fodder. Guinea pigs fed plant food exposed to hydrofluoric acid gases develop fluorosis, but with very small concentrations, death may occur only after a year or more. Cows afflicted with this disease due to fodder harvested in fluorine-infested areas show initial symptoms of lameness of one or more legs, stamping by the animal, resting on one leg and then the other, inability to rise, and spontaneous sprains and bone fractures occurring in the stable. After several months, the animal gradually grows thin with a dry, hard hide and eventually dies. Experiments with corpses of animals who died of fluorosis have shown that their bones are more brittle than those of normal healthy animals.

Benchtop Fluorination of Fluorescent Nanodiamonds on a Preparative Scale: Toward Unusually Hydrophilic Bright Particles

Czech Academy of Sciences Publication Activity Database

Havlík, Jan; Raabová, Helena; Gulka, Michal; Petráková, Vladimíra; Krečmarová, M.; Mašek, V.; Louša, Petr; Štursa, Jan; Boyen, H. G.; Nesládek, M.; Cígler, Petr

2016-01-01

Roč. 26, č. 23 (2016), s. 4134-4142 ISSN 1616-301X R&D Projects: GA MZd(CZ) NV15-33094A; GA MŠk(CZ) LM2011019; GA MŠk(CZ) LO1304; GA ČR(CZ) GA16-16336S Institutional support: RVO:61388963 ; RVO:68378271 ; RVO:61389005 Keywords : nitrogen-vacancy centers * catalyzed decarboxylative fluorination * surface modification Subject RIV: CC - Organic Chemistry Impact factor: 12.124, year: 2016

Synergistic Effect of Fluorinated and N Doped TiO2 Nanoparticles Leading to Different Microstructure and Enhanced Photocatalytic Bacterial Inactivation

Directory of Open Access Journals (Sweden)

Irena Milosevic

2017-11-01

Full Text Available This work focuses on the development of a facile and scalable wet milling method followed by heat treatment to prepare fluorinated and/or N-doped TiO2 nanopowders with improved photocatalytic properties under visible light. The structural and electronic properties of doped particles were investigated by various techniques. The successful doping of TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS, and the atoms appeared to be mainly located in interstitial positions for N whereas the fluorination is located at the TiO2 surface. The formation of intragap states was found to be responsible for the band gap narrowing leading to the faster bacterial inactivation dynamics observed for the fluorinated and N doped TiO2 particles compared to N-doped TiO2. This was attributed to a synergistic effect. The results presented in this study confirmed the suitability of the preparation approach for the large-scale production of cost-efficient doped TiO2 for effective bacterial inactivation.

Employment of fluorine doped zinc tin oxide (ZnSnOx:F) coating layer on stainless steel 316 for a bipolar plate for PEMFC

International Nuclear Information System (INIS)

Park, Ji Hun; Byun, Dongjin; Lee, Joong Kee

2011-01-01

Highlights: → Preparation of fluorine doped tin oxide (SnOx:F) and fluorine doped zinc tin oxide (ZnSnOx:F) coating layer on the surface of stainless steel 316 bipolar plate for PEMFCs (Proton Exchange Membrane Fuel Cells). → Evaluations of the corrosion resistance and the interfacial contact resistance of the bare, SnOx:F and ZnSnOx:F thin film coated stainless steel 316 bipolar plates. → Evaluation of single cell performance such as cell voltage and power density using bare stainless steel, SnOx:F and ZnSnOx:F film coated bipolar plates. - Abstract: The investigation of the electrochemical characteristics of the fluorine doped tin oxide (SnOx:F) and fluorine doped zinc tin oxide (ZnSnOx:F) was carried out in the simulated PEMFC environment and bare stainless steel 316 was used as a reference. The results showed that the ZnSnOx:F coating enhanced both the corrosion resistance and interfacial contact resistance (ICR). The corrosion current for ZnSnOx:F was 1.2 μA cm -2 which was much lower than that of bare stainless steel of 50.16 μA cm -2 . The ZnSnOx:F coated film had the smallest corrosion current due to the formation of a tight surface morphology with very few pin-holes. The ZnSnOx:F coated film exhibited the highest values of the cell voltage and power density due to its having the lowest ICR values.

Direct fluorination? Useful tool to enhance commercial properties of polymer articles

NARCIS (Netherlands)

Kharitonov, A.P.; Taege, R.; Ferrier, G.; Teplyakov, V.V.; Syrtsova, D.A.; Syrtsova, D.A.; Koops, G.H.

2005-01-01

Fundamental features and industrial applications of the direct fluorination of polymers are reviewed. Fundamental features of the direct fluorination of a set of polymers, such as polystyrene, polyethyleneterephthalate, poly(2,6-dimethyl-1,4-phenylene oxide), PMMA, LDPE (two types), HDPE (six

A system for the synthesis of uranium hexafluoride by high pressure fluorination of uranium oxides

International Nuclear Information System (INIS)

Elizalde T, J.; Saniger B, J.M.; Nava S, R.

1986-01-01

An equipment for the synthesis of uranium hexafluoride by a direct fluorination method is reported. The equipment is composed by a gaseous fluorine supply, a gas burette, a reactor tube inside a protective shield, a soda-lime chemical trap and a vacuum system. The fluorination is accomplished at a pressure of about 70 kg/cm 2 (1000 lb in 2 ), using gaseous fluorine. (Author). 5 refs, 4 figs, 2 tabs

[Health effects of fluorine and its compounds].

Science.gov (United States)

Kono, K

1994-12-01

Fluoride, the ionic form of fluorine, is a natural component of the biosphere and 13th most abundant element in the crust of the earth. It is, therefore, found in a wide range of concentrations in virtually all inanimate and living things. Many trace elements perform a definite function in human metabolism and the question of the value of fluoride, always found in the body, has been raised. Much evidence suggesting that the inclusion of fluoride in drinking water has beneficial as well as adverse effects on human health was obtained. Either alone or in combination with calcium and/or vitamin D, it is used in high daily doses for the treatment of osteoporosis. Although organic fluorine compounds are used in medicine and commerce, the inorganic fluorine compounds are of greater importance toxicologically because they are more readily available. The major pathway of fluoride elimination from the human body is via the kidney. When renal function deteriorates, the ability to excrete fluoride markedly decreases, possibly resulting in greater retention of fluoride in the body. At this point, more research is needed to evaluate the effects of physiological variables on the fluoride metabolism in humans.

40 CFR 721.9075 - Quaternary ammonium salt of fluorinated alkylaryl amide.

Science.gov (United States)

2010-07-01

... fluorinated alkylaryl amide. 721.9075 Section 721.9075 Protection of Environment ENVIRONMENTAL PROTECTION... amide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as quaternary ammonium salt of fluorinated alkylaryl amide (PMN No. P-92-688) is...

Fluorinated Poly(p-phenylenevinylenes: Synthesis and Optical Properties of an Intriguing Class of Luminescent Polymers

Directory of Open Access Journals (Sweden)

Gianluca M. Farinola

2010-05-01

Full Text Available This review is an overview of our previous work on the synthesis and properties of poly(p-phenylenevinylenes (PPVs selectively fluorinated in different positions of the conjugated backbone. Both the synthetic challenges and the effects of functionalization with fluorine atoms on the optical behavior are discussed, highlighting the peculiarities and the interest of this class of conjugated polymers. A general polymerization protocol for PPVs, that is based on the Pd-catalyzed Stille cross-coupling reaction of bis-stannylated vinylene monomers with aromatic bis-halides, has been successfully extended to the synthesis of selectively fluorinated poly(p-phenylenevinylenes. The properties of a series of these PPVs differing in the number and positions of the fluorine atoms on the conjugated backbone have been studied, even in comparison with the non-fluorinated counterparts. The intriguing optical features of the resulting materials are discussed considering not only the role of the electronic and steric effects induced by the fluorine substituents, but also the impact of the fluorination on the solid state organization and intermolecular interactions.

Defect pair formation in fluorine and nitrogen codoped TiO2

Science.gov (United States)

Kordatos, A.; Kelaidis, N.; Chroneos, A.

2018-04-01

Titanium oxide is extensively investigated because of its high chemical stability and its photocatalytic properties; nevertheless, the large band gap limits its activity to a small portion of the solar spectrum. Nitrogen and fluorine codoping is an efficient defect engineering strategy to increase the photocatalytic activity of titanium oxide. In the present study, we apply density functional theory to investigate the interaction of nitrogen with fluorine and the formation of defect pairs. We show that in fluorine and nitrogen codoped titanium oxide, the FiNi, FONi, and FiNTi defects can form. Their impact on the electronic structure of titanium oxide is discussed.

Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm

Science.gov (United States)

Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.

1988-01-01

Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

Fluorinated Polymers as Smart Materials for Advanced Biomedical Applications

Directory of Open Access Journals (Sweden)

Vanessa F. Cardoso

2018-02-01

Full Text Available Fluorinated polymers constitute a unique class of materials that exhibit a combination of suitable properties for a wide range of applications, which mainly arise from their outstanding chemical resistance, thermal stability, low friction coefficients and electrical properties. Furthermore, those presenting stimuli-responsive properties have found widespread industrial and commercial applications, based on their ability to change in a controlled fashion one or more of their physicochemical properties, in response to single or multiple external stimuli such as light, temperature, electrical and magnetic fields, pH and/or biological signals. In particular, some fluorinated polymers have been intensively investigated and applied due to their piezoelectric, pyroelectric and ferroelectric properties in biomedical applications including controlled drug delivery systems, tissue engineering, microfluidic and artificial muscle actuators, among others. This review summarizes the main characteristics, microstructures and biomedical applications of electroactive fluorinated polymers.

Generation of highly N-type, defect passivated transition metal oxides using plasma fluorine insertion

Science.gov (United States)

Baker, L. Robert; Seo, Hyungtak; Hervier, Antoine; Somorjai, Gabor A.

2016-04-12

A new composition of matter is disclosed wherein oxygen vacancies in a semiconducting transition metal oxide such as titanium dioxide are filled with a halogen such as Fluorine, whereby the conductivity of the composition is greatly enhanced, while at the same time the chemical stability of the composition is greatly improved. Stoichiometric titanium dioxide having less than 3 % oxygen vacancies is subject to fluorine insertion such that oxygen vacancies are filled, limited amounts of fluorine replace additional oxygen atoms and fluorine interstitially inserts into the body of the TiO.sub.2 composition.

Fluorine walk: The impact of fluorine in quinolone amides on their activity against African sleeping sickness.

Science.gov (United States)

Berninger, Michael; Erk, Christine; Fuß, Antje; Skaf, Joseph; Al-Momani, Ehab; Israel, Ina; Raschig, Martina; Güntzel, Paul; Samnick, Samuel; Holzgrabe, Ulrike

2018-05-25

Human African Trypanosomiasis, also known as African sleeping sickness, is caused by the parasitic protozoa of the genus Trypanosoma. If there is no pharmacological intervention, the parasites can cross the blood-brain barrier (BBB), inevitably leading to death of the patients. Previous investigation identified the quinolone amide GHQ168 as a promising lead compound having a nanomolar activity against T. b. brucei. Here, the role of a fluorine substitution at different positions was investigated in regard to toxicity, pharmacokinetics, and antitrypanosomal activity. This 'fluorine walk' led to new compounds with improved metabolic stability and consistent activity against T. b. brucei. The ability of the new quinolone amides to cross the BBB was confirmed using an 18 F-labelled quinolone amide derivative by means of ex vivo autoradiography of a murine brain. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Avoidance of fluorinated greenhouse gases. Possibilities of an early exit; Fluorierte Treibhausgase vermeiden. Wege zum Ausstieg

Energy Technology Data Exchange (ETDEWEB)

Becken, Katja; Graaf, Daniel de; Elsner, Cornelia; Hoffmann, Gabriele; Krueger, Franziska; Martens, Kerstin; Plehn, Wolfgang; Sartorius, Rolf

2010-11-15

In comparison to carbon dioxide, fluorinated greenhouse gases are more harmful up to a factor of 24,000. Today the amount of fluorinated greenhouse gases of the world-wide emissions of climatic harmful gases amounts 2 % and increases to 6 % in the year 2050. The authors of the contribution under consideration report on possibilities for the avoidance of the emissions of fluorinated greenhouse gases. The characteristics and ecological effects of fluorinated gases as well as the development of the emission in Germany are presented. Subsequently, the applications of fluorinated hydrocarbons are described.

Photochemistry of fluorinated 4-iodophenylnitrenes: matrix isolation and spectroscopic characterization of phenylnitrene-4-yls.

Science.gov (United States)

Grote, Dirk; Sander, Wolfram

2009-10-02

The photochemistry of a series of fluorinated p-iodophenyl azides 2 has been investigated using matrix isolation IR and EPR spectroscopy. In all cases, the corresponding phenylnitrenes 1 were formed as primary photoproducts. Further irradiation of the nitrenes 1 resulted in the formation of azirines 3, ketenimines 4, and nitreno radicals 5. The yield of 5 depends on the number of ortho fluorine substituents: with two ortho fluorine atoms the highest yield is observed, whereas without fluorine atoms the yield is too low for IR spectroscopic detection. The interconversion between the isomers 1, 3, and 4 proved to be rather complex. If the fluorine atoms are distributed unsymmetrically, two isomers of azirines 3 and ketenimines 4 can be formed. The yields of these isomers depend critically on the irradiation conditions.

Application of PIGE to determine fluorine concentration in human teeth. Contribution to fluorosis study

International Nuclear Information System (INIS)

Salah, H.; Arab, N.

2007-01-01

Fluorosis, osteoselerosis, and systemic illness may result when tolerance levels of fluorine intake are exceeded. To avoid these abnormalities, we shall be aware of the mechanisms of their development. For this, quantitative results gathered from different parts of the world are necessary. In this paper, PIGE method is used to determine fluorine concentration in human teeth, collected from different regions of the Algerian Sahara. Both enamel and dentine regions were inspected. The external and internal mappings of the analyzed teeth have shown more variation in the localized fluorine concentration in dentine than in enamel, and the lowest level of fluorine concentration was observed in the frontier crown-root zone. The obtained results reveal relatively high fluorine concentration lying within the limit of fluorosis, according to the standardised grading dental fluorosis. (author)

Oxygen plasma treatment and deposition of CNx on a fluorinated polymer matrix composite for improved erosion resistance

International Nuclear Information System (INIS)

Muratore, C.; Korenyi-Both, A.; Bultman, J. E.; Waite, A. R.; Jones, J. G.; Storage, T. M.; Voevodin, A. A.

2007-01-01

The use of polymer matrix composites in aerospace propulsion applications is currently limited by insufficient resistance to erosion by abrasive media. Erosion resistant coatings may provide necessary protection; however, adhesion to many high temperature polymer matrix composite (PMC) materials is poor. A low pressure oxygen plasma treatment process was developed to improve adhesion of CN x coatings to a carbon reinforced, fluorinated polymer matrix composite. Fullerene-like CN x was selected as an erosion resistant coating for its high hardness-to-elastic modulus ratio and elastic resilience which were expected to reduce erosion from media incident at different angles (normal or glancing) relative to the surface. In situ x-ray photoelectron spectroscopy was used to evaluate the effect of the plasma treatment on surface chemistry, and electron microscopy was used to identify changes in the surface morphology of the PMC substrate after plasma exposure. The fluorine concentration at the surface was significantly reduced and the carbon fibers were exposed after plasma treatment. CN x coatings were then deposited on oxygen treated PMC substrates. Qualitative tests demonstrated that plasma treatment improved coating adhesion resulting in an erosion resistance improvement of a factor of 2 compared to untreated coated composite substrates. The combination of PMC pretreatment and coating with CN x reduced the erosion rate by an order of magnitude for normally incident particles

Magnetic phase investigations on fluorine (F) doped LiFePO4

Science.gov (United States)

Radhamani, A. V.

2018-03-01

LiFePO4 (LFP) is a very promising cathode material for Li-ion batteries due to its high thermal stability, less toxicity and high theoretical capacity (170 mAh g-1). Anion doping, especially fluorine (F) at the oxygen site is one way to improve the low electronic conductivity of the material. In this line, fluorine doped LFP was prepared at different fluorine concentrations (1 to 40 mol%) to study the structural, spectroscopic and magnetic properties in view of the material property optimization for battery applications. The investigation of the magnetic properties was found to be successful for the determination of small amounts of magnetic impurities which were not noticeably observed from structural characterizations. Determination of conducting magnetic impurities has its own relevance in the current scenario of Li-ion based battery applications. Systematic characterization studies along with the implications of magnetic phases on the material activity of fluorine doped LiFePO4 nanoparticles will be discussed in detail.

X-ray photoelectron spectroscopy as detection tool for coordinated or uncoordinated fluorine atoms demonstrated on fluoride systems NaF, K2TaF7, K3TaF8, K2ZrF6, Na7Zr6F31 and K3ZrF7

Science.gov (United States)

Boča, Miroslav; Barborík, Peter; Mičušík, Matej; Omastová, Mária

2012-07-01

While systems K3TaF8 and K3ZrF7 were prepared by modified molten salt method modified wet pathway was used for reproducible preparation of Na7Zr6F31. Its congruently melting character was demonstrated on simultaneous TG/DSC measurements and XRD patterns. X-ray photoelectron spectroscopy was applied for identification of differently bonded fluorine atoms in series of compounds NaF, K2TaF7, K3TaF8, K2ZrF6, Na7Zr6F31 and K3ZrF7. Three different types of fluorine atoms were described qualitatively and quantitatively. Uncoordinated fluorine atoms (F-) provide signals at lowest binding energies, followed by signals from terminally coordinated fluorine atoms (M-F) and then bridging fluorine atoms (M-F-M) at highest energy. Based on XPS F 1s signals assigned to fluorine atoms in compounds with correctly determined structure it was suggested that fluorine atoms in K3ZrF7 have partially bridging character.

The investigation of the fluorine uptake in tooth enamel after the application of a NaF containing varnish

Science.gov (United States)

Plier, F.; Zschau, H. E.; Otto, G.

1992-03-01

The 935 keV resonance of the 19F( p, p' γ) 19F nuclear reaction was used to determine flourine depth profiles in human tooth enamel for three separate cases. These investigations allowed conclusions to be drawn about the interaction processes between the oral milieu containing fluorine, and the enamel surface.

Determination of fluorine in fodder phosphates and phosphorite flour by fast neutron activation method

International Nuclear Information System (INIS)

Abashin, E.G.; Lisovskij, I.P.; Smakhtin, L.A.

1980-01-01

A neutron-activation method is suggested for determination of fluorine in fodder phosphates and phosphorite flour. Used as the source of fast neutrons was an NG-150M neutron generator with a maximum yield of 10 8 nxcm -2 xs -1 . Samples were irradiated in polyethylene ampoules using a pneumatic shuttle. Fluorine was determined with reference to the fluorine-18 isotope. The accuracy of determining fluorine in fodder phosphates and phosphorite flour is 1 to 4% (rel.) at a rate of not less than 10 samples per hour. The method is suitable for in-process testing of products

Determination of fluorine in fodder phosphates and phosphorite flour by fast neutron activation method

Energy Technology Data Exchange (ETDEWEB)

Abashin, E G; Lisovskii, I P; Smakhtin, L A

1980-01-01

A neutron-activation method is suggested for determination of fluorine in fodder phosphates and phosphorite flour. Used as the source of fast neutrons was an NG-150M neutron generator with a maximum yield of 10/sup 8/ nxcm/sup -2/xs/sup -1/. Samples were irradiated in polyethylene ampoules using a pneumatic shuttle. Fluorine was determined with reference to the fluorine-18 isotope. The accuracy of determining fluorine in fodder phosphates and phosphorite flour is 1 to 4% (rel.) at a rate of not less than 10 samples per hour. The method is suitable for in-process testing of products.

Fluorine-18 heart dosimetry in myocardial perfusion imaging

Energy Technology Data Exchange (ETDEWEB)

Toledo, Janine M.; Trindade, Bruno; Campos, Tarcísio P.R., E-mail: janine.toledo@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Programa de Pós-Graduação em Ciências e Técnicas Nucleares

2017-07-01

This paper conducts a recalling in myocardial perfusion imaging (MPI) followed by a spatial dosimetric investigation of the Fluorine-18 distributed at the myocardium by self-absorption of the heart uptake. Methods and Results: Radiological data manipulation was prepared and a computational heart voxelized model was assembled. A set of images from the abdominal aorta and angiotomography of the thorax was set up providing anatomic and functional information for heart modeling in SISCODES code. A homogeneous distribution of fluorine-18 was assumed into the heart myocardial wall. MCNP – Monte Carlo Code was used to provide the photon transport into the heart model taken in consideration the interactions into the tissues. The spatial dose distribution and histogram dose versus volume are presented. An analytical alternative model was addressed to the data validation. The present developed tools can produce spatial dose distribution in MPI at heart. Specially, the dosimetry performed elucidates imparted dose in the myocardial muscle per unit of injected Fluorine-18 activity by self-absorption of the heart uptake, which can contribute to future deterministic effect investigations. (author)

Fluorine-18 heart dosimetry in myocardial perfusion imaging

International Nuclear Information System (INIS)

Toledo, Janine M.; Trindade, Bruno; Campos, Tarcísio P.R.

2017-01-01

This paper conducts a recalling in myocardial perfusion imaging (MPI) followed by a spatial dosimetric investigation of the Fluorine-18 distributed at the myocardium by self-absorption of the heart uptake. Methods and Results: Radiological data manipulation was prepared and a computational heart voxelized model was assembled. A set of images from the abdominal aorta and angiotomography of the thorax was set up providing anatomic and functional information for heart modeling in SISCODES code. A homogeneous distribution of fluorine-18 was assumed into the heart myocardial wall. MCNP – Monte Carlo Code was used to provide the photon transport into the heart model taken in consideration the interactions into the tissues. The spatial dose distribution and histogram dose versus volume are presented. An analytical alternative model was addressed to the data validation. The present developed tools can produce spatial dose distribution in MPI at heart. Specially, the dosimetry performed elucidates imparted dose in the myocardial muscle per unit of injected Fluorine-18 activity by self-absorption of the heart uptake, which can contribute to future deterministic effect investigations. (author)

Analysis of energy flow during playground surface impacts.

Science.gov (United States)

Davidson, Peter L; Wilson, Suzanne J; Chalmers, David J; Wilson, Barry D; Eager, David; McIntosh, Andrew S

2013-10-01

The amount of energy dissipated away from or returned to a child falling onto a surface will influence fracture risk but is not considered in current standards for playground impact-attenuating surfaces. A two-mass rheological computer simulation was used to model energy flow within the wrist and surface during hand impact with playground surfaces, and the potential of this approach to provide insights into such impacts and predict injury risk examined. Acceleration data collected on-site from typical playground surfaces and previously obtained data from children performing an exercise involving freefalling with a fully extended arm provided input. The model identified differences in energy flow properties between playground surfaces and two potentially harmful surface characteristics: more energy was absorbed by (work done on) the wrist during both impact and rebound on rubber surfaces than on bark, and rubber surfaces started to rebound (return energy to the wrist) while the upper limb was still moving downward. Energy flow analysis thus provides information on playground surface characteristics and the impact process, and has the potential to identify fracture risks, inform the development of safer impact-attenuating surfaces, and contribute to development of new energy-based arm fracture injury criteria and tests for use in conjunction with current methods.

Copolymers of fluorinated polydienes and sulfonated polystyrene

Science.gov (United States)

Mays, Jimmy W [Knoxville, TN; Gido, Samuel P [Hadley, MA; Huang, Tianzi [Knoxville, TN; Hong, Kunlun [Knoxville, TN

2009-11-17

Copolymers of fluorinated polydienes and sulfonated polystyrene and their use in fuel cell membranes, batteries, breathable chemical-biological protective materials, and templates for sol-gel polymerization.

H18F: production and use in aromatic fluorinations via triazenes

International Nuclear Information System (INIS)

Kilbourn, M.R.; Saji, H.; Welch, M.J.

1982-01-01

Studies with the triazene method of radiofluorination are presented, including the production and use of anhydrous H 18 F, investigations into the best reaction conditions, and studies of the stability and purification of the 18 F-labeled products. Despite problems with low yields, the use of triazenes in the prepartion of fluorine-18 labeled receptor ligands remains a sound synthetic approach, and the only one available for no-carrier-added syntheses. However, it appears that the fluorine-18 fluorination yields are much higher with simpler triazenes. For this reason, synthetic efforts are now focused on the preparation of 18 F-spiroperidol by a convergent synthesis

Fluorine determinations in biological materials by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Demiralp, R.; Guinn, V.P.; Becker, D.A.

1992-01-01

Exploratory studies were carried out at the University of California, Irvine on several freeze-dried human diet materials and on two freeze-dried vegetation materials - all prospective reference materials. The University of California, Irvine equipment includes a 250-kW TRIGA Mark 1 reactor, 2.5 x 10 12 n/cm 2 ·s thermal flux, 3-s sample transfer time, and a typical 18% Ge(Li)/4,096-channel gamma-ray spectrometer with a detector resolution of 3.3 keV at 1,332 keV. In these exploratory studies, it was found that it was not feasible to measure fluorine with adequate precision or accuracy at fluorine concentrations much less than ∼100 ppm. These initial studies, however, defined the magnitudes of the various difficulties. One good outcome of these studies was the demonstration that the otherwise excellent Teflon-mill brittle-fracture method for homogenizing freeze-dried biological samples was not suitable if fluorine was to be determined. Abrasion of the Teflon increased the fluorine content of a human diet sample about sevenfold (compared with similar treatment of the same material in an all-titanium mill)

Versatile synthesis and biological evaluation of novel 3’-fluorinated purine nucleosides

Directory of Open Access Journals (Sweden)

Hang Ren

2015-12-01

Full Text Available A unified synthetic strategy accessing novel 3'-fluorinated purine nucleoside derivatives and their biological evaluation were achieved. Novel 3’-fluorinated analogues were constructed from a common 3’-deoxy-3’-fluororibofuranose intermediate. Employing Suzuki and Stille cross-coupling reactions, fifteen 3’-fluororibose purine nucleosides 1–15 and eight 3’-fluororibose 2-chloro/2-aminopurine nucleosides 16–23 with various substituents at position 6 of the purine ring were efficiently synthesized. Furthermore, 3’-fluorine analogs of natural products nebularine and 6-methylpurine riboside were constructed via our convergent synthetic strategy. Synthesized nucleosides were tested against HT116 (colon cancer and 143B (osteosarcoma cancer tumor cell lines. We have demonstrated 3’-fluorine purine nucleoside analogues display potent tumor cell growth inhibition activity at sub- or low micromolar concentration.

Synthesis and ATRP of novel fluorinated aromatic monomer with pendant sulfonate group

DEFF Research Database (Denmark)

Dimitrov, Ivaylo; Jankova Atanasova, Katja; Hvilsted, Søren

2013-01-01

Novel, fluorinated monomer with pendant sulfonate group was synthesized utilizing a two-step derivatization of 2,3,4,5,6-pentafluorostyrene (FS). The first step was a nucleophilic substitution of the fluorine atom in para position by hydroxyl group followed by sulfopropylation. The monomer...... was polymerized under aqueous ATRP conditions to yield phenyl-fluorinated aromatic homopolymer bearing pendant sulfonates on each repeating unit. Furthermore, this polymer was used as macroinitiator for the ATRP of poly(ethylene glycol) methacrylate. The polymers were characterized by 1H NMR, SEC and FTIR...

Observance to the teeth casts of fluorination after head and neck irradiation

International Nuclear Information System (INIS)

Albarghach, N.; Righini, C.; Thariat, J.

2009-01-01

The application of teeth casts with fluorinated gel is omitted in practice after six months for most of patients. The reasons can be an inadequate information on the application time of casts, mucitis pain during excessive application of fluorinated gel during irradiation creating then, apprehension of fluorinated gels. A questionnaire of observance during the consultation can be an education tool. repeated for the same patients at the next follow up consultation and compared it could allow to measure the impact of awareness measures during the follow up. (N.C.)

Development of F2 two-step fluorination process for non-aqueous reprocessing

International Nuclear Information System (INIS)

1976-02-01

To establish the F 2 two-step fluorination for stable and high recoveries of plutonium, the fluorination process has been studied with the simulated fuel to a FBR containing UO 2 - PuO 2 and non-radioactive fission products in the 2''phi fluid-bed. The process principle was demonstrated and the effect of FPs on fluorination of U and Pu and the possibility of reducing the Pu loss could be clarified. The feasibility of separating PuF 6 from UF 6 onto UO 2 F 2 by adsorption, was also indicated. (auth.)

A Surface Temperature Initiated Closure (STIC) for surface energy balance fluxes

DEFF Research Database (Denmark)

Mallick, Kaniska; Jarvis, Andrew J.; Boegh, Eva

2014-01-01

The use of Penman–Monteith (PM) equation in thermal remote sensing based surface energy balance modeling is not prevalent due to the unavailability of any direct method to integrate thermal data into the PM equation and due to the lack of physical models expressing the surface (or stomatal......) and boundary layer conductances (gS and gB) as a function of surface temperature. Here we demonstrate a new method that physically integrates the radiometric surface temperature (TS) into the PM equation for estimating the terrestrial surface energy balance fluxes (sensible heat, H and latent heat, λ......E). The method combines satellite TS data with standard energy balance closure models in order to derive a hybrid closure that does not require the specification of surface to atmosphere conductance terms. We call this the Surface Temperature Initiated Closure (STIC), which is formed by the simultaneous solution...

Chronic intestinal intoxication with fluorine

Energy Technology Data Exchange (ETDEWEB)

Cristiani, H; Gautier, R

1925-01-01

The accumulation of fluorine in bones of guinea pigs which died of an osteomalacia-like condition is described. The time required for the condition to develop varied from a few weeks to several months when hay with a F content of 1:1000 to 1:10000 was used as food.

Fluorine-enhanced low-temperature wafer bonding of native-oxide covered Si wafers

Science.gov (United States)

Tong, Q.-Y.; Gan, Q.; Fountain, G.; Enquist, P.; Scholz, R.; Gösele, U.

2004-10-01

The bonding energy of bonded native-oxide-covered silicon wafers treated in the HNO3/H2O/HF or the HNO3/HF solution prior to room-temperature contact is significantly higher than bonded standard RCA1 cleaned wafer pairs after low-temperature annealing. The bonding energy reaches over 2000mJ/m2 after annealing at 100 °C. The very slight etching and fluorine in the chemically grown oxide are believed to be the main contributors to the enhanced bonding energy. Transmission-electron-microscopic images have shown that the chemically formed native oxide at bonding interface is embedded with many flake-like cavities. The cavities can absorb the by-products of the interfacial reactions that result in covalent bond formation at low temperatures allowing the strong bond to be retained.

Multilayer Relaxation and Surface Energies of Metallic Surfaces

Science.gov (United States)

Bozzolo, Guillermo; Rodriguez, Agustin M.; Ferrante, John

1994-01-01

The perpendicular and parallel multilayer relaxations of fcc (210) surfaces are studied using equivalent crystal theory (ECT). A comparison with experimental and theoretical results is made for AI(210). The effect of uncertainties in the input parameters on the magnitudes and ordering of surface relaxations for this semiempirical method is estimated. A new measure of surface roughness is proposed. Predictions for the multilayer relaxations and surface energies of the (210) face of Cu and Ni are also included.

Emergence of Dirac and quantum spin Hall states in fluorinated monolayer As and AsSb

KAUST Repository

Zhang, Qingyun

2016-01-21

Using first-principles calculations, we investigate the electronic and vibrational properties of monolayer As and AsSb. While the pristine monolayers are semiconductors (direct band gap at the Γ point), fluorination results in Dirac cones at the K points. Fluorinated monolayer As shows a band gap of 0.16 eV due to spin-orbit coupling, and fluorinated monolayer AsSb a larger band gap of 0.37 eV due to inversion symmetry breaking. Spin-orbit coupling induces spin splitting similar to monolayer MoS2. Phonon calculations confirm that both materials are dynamically stable. Calculations of the edge states of nanoribbons by the tight-binding method demonstrate that fluorinated monolayer As is topologically nontrivial in contrast to fluorinated monolayer AsSb.

Fluorinated epoxy resins with high glass transition temperatures

Science.gov (United States)

Griffith, James R.

1991-01-01

Easily processed liquid resins of low dielectric constants and high glass transition temperatures are useful for the manufacture of certain composite electronic boards. That combination of properties is difficult to acquire when dielectric constants are below 2.5, glass transition temperatures are above 200 C and processability is of conventional practicality. A recently issued patent (US 4,981,941 of 1 Jan. 1991) teaches practical materials and is the culmination of 23 years of research and effort and 15 patents owned by the Navy in the field of fluorinated resins of several classes. In addition to high fluorine content, practical utility was emphasized.

Magnetic study of solid uranium-fluorine complexes; Contribution a l'etude magnetique de composes fluores solides de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Dianoux, A J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-06-01

A study of the magnetic susceptibility of uranium V fluorine complexes and of the magnetic resonance of fluorine atoms in uranium VI fluorine complexes has made it possible to put forward a structural model for these compounds for which it is impossible, because of the lack of suitable single crystals for X-ray diffraction work, to deduce the exact position of the fluorine atoms. It is shown that it is difficult to interpret the paramagnetism of uranium fluorides, because the uranium ions are in low-symmetry sites. A theoretical study of the magnetism of the U{sup V} ion in complex fluorides of the type M{sub 3}UF{sub 8} (M = NH{sub 4}, Na, Rb, Cs) leads to an interpretation based on a trigonal deformation of the eight fluorine atom structure surrounding the uranium atom. By applying a Hamiltonian spin formalism and making a systematic use of group theory, it is possible to present the susceptibility calculations very concisely. Study of the resonance and of the relaxation of the fluorine atoms in powdered uranium VI complex fluorides suggests a structural model in the case of NaUF{sub 7}. It is shown that the shape of the magnetic resonance absorption lines is strongly affected by the presence of large anisotropic chemical shifts. In the model proposed here, six fluorine atoms are linked to the uranium, atom by strongly covalent bonds in a deformed UF{sub 6} octahedral structure; the seventh fluorine atom remains ionic. The occurrence of a rotational movement of the octahedron is confirmed by a study of the longitudinal relaxation of the fluorine atoms, the activation energy being 0.46 eV. (author) [French] L'etude de la susceptibilite magnetique de complexes fluores d'uranium V et la resonance magnetique des fluors dans des complexes fluores d'uranium VI permettent de proposer un modele structural pour ces composes, ou la diffraction des rayons X, en l'absence de monocristaux convenables, est incapable de preciser la position des atomes de fluor. Nous montrons

Fluorine doped vanadium dioxide thin films for smart windows

International Nuclear Information System (INIS)

Kiri, Pragna; Warwick, Michael E.A.; Ridley, Ian; Binions, Russell

2011-01-01

Thermochromic fluorine doped thin films of vanadium dioxide were deposited from the aerosol assisted chemical vapour deposition reaction of vanadyl acetylacetonate, ethanol and trifluoroacetic acid on glass substrates. The films were characterised with scanning electron microscopy, variable temperature Raman spectroscopy and variable temperature UV/Vis spectroscopy. The incorporation of fluorine in the films led to an increase in the visible transmittance of the films whilst retaining the thermochromic properties. This approach shows promise for improving the aesthetic properties of vanadium dioxide thin films.

Study of the chemical species of fluorine 18 produced by neutron irradiation of lithium aluminate

International Nuclear Information System (INIS)

Jimenez-Becerril, J.

1990-01-01

In the present work, the chemical form of fluorine-18 obtained by means of the neutron irradiated lithium aluminate was studied, in order to know its chemical behavior and to observe if it volatilizes and adheres to the walls of a tritium distillation system; for this matter paper chromatography and high voltage electrophoresis techniques were used. Lithium aluminate was synthetized, being characterized as LiAlO 2 which was irradiated with neutrons in order to produce fluorine-18. Lithium aluminate is a non-soluble solid, therefore fluorine produced may not be extracted, unless it is dissolved or extracted through the solid. So as not affect in a drastic way the chemical form, it was submitted to extraction processes, agitating the irradiated samples with different acids and basic solutions in order to analyze fluorine-18. The best extraction agent was found to be HCl, where two forms of fluorine-18 were found, one at the point of application, probably as a complex hexafluoride-aluminate and the other as a characteristic Rf of the fluorine ion. In the tritium distillation with helium as a carrier of a sample irradiated and heated up to 220-250 o C, no volatile types of fluorine-18 were found, thus it can be considered that in commercial production of tritium by means of neutron irradiation of lithium aluminate, fluorine-18 is not a damaging pollutant of the equipment pipe system. (Author)

A systematic first-principles study of surface energies, surface relaxation and Friedel oscillation of magnesium surfaces

International Nuclear Information System (INIS)

Tang, Jia-Jun; Yang, Xiao-Bao; Zhao, Yu-Jun; OuYang, LiuZhang; Zhu, Min

2014-01-01

We systematically study the surface energies and surface relaxations of various low-index and high-index Mg surfaces. It is found that low-index surfaces are not necessarily stable as Mg(1 0  1-bar  0) is the most unstable surface in the series of Mg(1 0  1-bar  n) (n = 0–9). A surface-energy predicting model based on the bond cutting is proposed to explain the relative surface stabilities. The local relaxations of the low-index surfaces could be explained by the Friedel oscillation. For the high-index surfaces, the combination of charge smoothing effect and dramatic charge depletion influences the relaxations, which show a big difference from the low-index ones. Our findings provide theoretical data for considerable insights into the surface energies of hexagonal close-packed metals. (paper)

Modification of carbon nanotubes with fluorinated ionic liquid for improving processability of fluoro-ethylene-propylene

Energy Technology Data Exchange (ETDEWEB)

Ma, Hongyang; Chu, Benjamin; Hsiao, Benjamin S.

2017-02-01

Fluorinated ionic liquid (F-IL), 1-(3-perfluorooctylpropyl)-3-methylimidazolium bis(perfluoroethylsufonyl)amine, had been successfully prepared and employed to modify multi-wall carbon nanotubes (MWCNTs) for improving the processability of fluoro-ethylene-propylene (FEP). The thermally decomposed temperature of F-IL was higher than 350 °C measured by thermal gravimetric analysis (TGA) which indicated that the fluorinated ionic liquid could be suitable for melting blend with FEP (blending at 290 °C) by a twin-screw extruder. Through “cation-π” interaction between the imidazolium cation of F-IL and the graphene surface of MWCNTs, MWCNTs can be modified with F-IL and used as nanofillers to improve the dispersity of MWCNTs in fluorocopolymer FEP verified by SEM images of the FEP nanocomposite. The structural characterization and mechanical property of FEP nanocomposite during the deformation were investigated by tensile experiments and simultaneous time-resolved wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques.

Studies on the sensitivity of several plant species to fluorine gases in Valais

Energy Technology Data Exchange (ETDEWEB)

Bolay, A; Bovay, E

1965-01-01

Analysis of apricot, apple and vine leaves showed that at leaf fluorine concentrations up to 25 p.p.m. the foliage was generally free of burns, except that of apricot which showed some damage at a level of 15 p.p.m. Between 26 and 105 p.p.m. the reactions of the foliage were variable, depending on the vegetative state of the plant and on atmospheric conditions (mainly R.H. and rainfall). Above 105 p.p.m. burns were nearly always present on apricot and vine leaves; for apple foliage the toxic level was about 160 p.p.m. The 75 plant species studied were divided into 4 categories depending on their susceptibility to fluorine damage; very susceptible species were those showing typical burning of the leaves when the fluorine content of apricot and vine leaves growing in the immediate vicinity was lower than 100 p.p.m.; susceptible species were those showing necrosis when the fluorine content of apricot leaves was slightly higher than 100 p.p.m.; species of low sensitivity showed necrosis only in heavily polluted zones; and tolerant species were those able to store over 500 p.p.m. fluorine in their leaves without showing visible damage. The very susceptible species may be used as indicators of fluorine in the atmosphere.

Surface Meteorology and Solar Energy

Data.gov (United States)

National Aeronautics and Space Administration — Surface Meteorology and Solar Energy data - over 200 satellite-derived meteorology and solar energy parameters, monthly averaged from 22 years of data, global solar...

A Facile in Situ and UV Printing Process for Bioinspired Self-Cleaning Surfaces

Directory of Open Access Journals (Sweden)

Marina A. González Lazo

2016-08-01

Full Text Available A facile in situ and UV printing process was demonstrated to create self-cleaning synthetic replica of natural petals and leaves. The process relied on the spontaneous migration of a fluorinated acrylate surfactant (PFUA within a low-shrinkage acrylated hyperbranched polymer (HBP and its chemical immobilization at the polymer-air interface. Dilute concentrations of 1 wt. % PFUA saturated the polymer-air interface within 30 min, leading to a ten-fold increase of fluorine concentration at the surface compared with the initial bulk concentration and a water contact angle (WCA of 108°. A 200 ms flash of UV light was used to chemically crosslink the PFUA at the HBP surface prior to UV printing with a polydimethylsiloxane (PDMS negative template of red and yellow rose petals and lotus leaves. This flash immobilization hindered the reverse migration of PFUA within the bulk HBP upon contacting the PDMS template, and enabled to produce texturized surfaces with WCA well above 108°. The synthetic red rose petal was hydrophobic (WCA of 125° and exhibited the adhesive petal effect. It was not superhydrophobic due to insufficient concentration of fluorine at its surface, a result of the very large increase of the surface of the printed texture. The synthetic yellow rose petal was quasi-superhydrophobic (WCA of 143°, roll-off angle of 10° and its self-cleaning ability was not good also due to lack of fluorine. The synthetic lotus leaf did not accurately replicate the intricate nanotubular crystal structures of the plant. In spite of this, the fluorine concentration at the surface was high enough and the leaf was superhydrophobic (WCA of 151°, roll-off angle below 5° and also featured self-cleaning properties.

Results of the topical in vitro and in vivo fluorination of dental enamel

International Nuclear Information System (INIS)

Baijot-Stroobants, J.; Deconninck, G.; Vreven, J.

1978-01-01

Fluorine in human enamel has been analysed by proton bombardment and detection of prompt γ-rays. Proton beam is used at atmospheric pressure; two different sets of experiments are reported: the first one consists in studying fluoridation effects on extracted teeth and the second one in making in vivo Fluorine determinations before and after topical applications. Several commercial gels and solutions have been tested with regard to their efficiency for Fluorine fixation: in vitro and in vivo results are in good agreement. (author)

Detection sensitivity of fluorine in dental enamel through the 19F(p,psup(')γ)19F reaction

International Nuclear Information System (INIS)

Papper, C.S.; Chittleborough, G.; Kennett, S.R.; Chaudhri, M.A.

1978-01-01

The total cross sections for production of 109 and 197 keV gamma rays in the reaction 19 F(p,psup(')γ) 19 F have been measured, over a range of energies up to 4.3 MeV. From these cross sections, the thick detection sensitivities for a uniform distribution of fluorine in dental enamel have been calculated

Fluorine and chlorine determination in oxides and metals by ion chromatography

International Nuclear Information System (INIS)

Evseeva, T.I.; Poletaeva, I.L.; Zemlyanukhina, N.A.; Pavlova, I.V.; Rybin, A.M.; Malykh, M.Yu.; Fedorova, L.A.

1989-01-01

Method for simultaneous determination of fluorine and chlorine microquantitie in tantalum, uranium and plutonium oxides, based on combined methods of pyrohydrolysis (1000-1100 deg C) and two-column ion chromatography with conductometric detection is suggested. The relative root-mean-square deviation of determination error is 0.2, the fluorine and chlorine content being 5·10 -4 mass%

Physicochemical characterization of point defects in fluorine doped tin oxide films

Science.gov (United States)

Akkad, Fikry El; Joseph, Sudeep

2012-07-01

The physical and chemical properties of spray deposited FTO films are studied using FESEM, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), electrical and optical measurements. The results of XRD measurements showed that the films are polycrystalline (grain size 20-50 nm) with Rutile structure and mixed preferred orientation along the (200) and (110) planes. An angular shift of the XRD peaks after F-doping is observed and interpreted as being due to the formation of substitutional fluorine defects (FO) in presence of high concentration of oxygen vacancies (VO) that are electrically neutral. The electrical neutrality of oxygen vacancies is supported by the observation that the electron concentration n is two orders of magnitude lower than the VO concentration calculated from chemical analyses using XPS measurements. It is shown that an agreement between XPS, XRD, and Hall effect results is possible provided that the degree of deviation from stoichiometry is calculated with the assumption that the major part of the bulk carbon content is involved in O-C bonds. High temperature thermal annealing is found to cause an increase in the FO concentration and a decrease in both n and VO concentrations with the increase of the annealing temperature. These results could be interpreted in terms of a high temperature chemical exchange reaction between the SnO2 matrix and a precipitated fluoride phase. In this reaction, fluorine is released to the matrix and Sn is trapped by the fluoride phase, thus creating substitutional fluorine FO and tin vacancy VSn defects. The enthalpy of this reaction is determined to be approximately 2.4 eV while the energy of formation of a VSn through the migration of SnSn host atom to the fluoride phase is approximately 0.45 eV.

The surface energy of metals

DEFF Research Database (Denmark)

Vitos, Levente; Ruban, Andrei; Skriver, Hans Lomholt

1998-01-01

We have used density functional theory to establish a database of surface energies for low index surfaces of 60 metals in the periodic table. The data may be used as a consistent starting point for models of surface science phenomena. The accuracy of the database is established in a comparison...

Energy conservation potential of surface modification technologies

Energy Technology Data Exchange (ETDEWEB)

Le, H.K.; Horne, D.M.; Silberglitt, R.S.

1985-09-01

This report assesses the energy conservation impact of surface modification technologies on the metalworking industries. The energy conservation impact of surface modification technologies on the metalworking industries is assessed by estimating their friction and wear tribological sinks and the subsequent reduction in these sinks when surface modified tools are used. Ion implantation, coatings, and laser and electron beam surface modifications are considered.

Reversible Changes in Resistance of Perovskite Nickelate NdNiO3 Thin Films Induced by Fluorine Substitution.

Science.gov (United States)

Onozuka, Tomoya; Chikamatsu, Akira; Katayama, Tsukasa; Hirose, Yasushi; Harayama, Isao; Sekiba, Daiichiro; Ikenaga, Eiji; Minohara, Makoto; Kumigashira, Hiroshi; Hasegawa, Tetsuya

2017-03-29

Perovskite nickel oxides are of fundamental as well as technological interest because they show large resistance modulation associated with phase transition as a function of the temperature and chemical composition. Here, the effects of fluorine doping in perovskite nickelate NdNiO 3 epitaxial thin films are investigated through a low-temperature reaction with polyvinylidene fluoride as the fluorine source. The fluorine content in the fluorinated NdNiO 3-x F x films is controlled with precision by varying the reaction time. The fully fluorinated film (x ≈ 1) is highly insulating and has a bandgap of 2.1 eV, in contrast to NdNiO 3 , which exhibits metallic transport properties. Hard X-ray photoelectron and soft X-ray absorption spectroscopies reveal the suppression of the density of states at the Fermi level as well as the reduction of nickel ions (valence state changes from +3 to +2) after fluorination, suggesting that the strong Coulombic repulsion in the Ni 3d orbitals associated with the fluorine substitution drives the metal-to-insulator transition. In addition, the resistivity of the fluorinated films recovers to the original value for NdNiO 3 after annealing in an oxygen atmosphere. By application of the reversible fluorination process to transition-metal oxides, the search for resistance-switching materials could be accelerated.

Characteristics of fluorinated nitroazoles as hypoxic cell radiosensitizers

International Nuclear Information System (INIS)

Shibamoto, Y.; Nishimoto, S.; Shimokawa, K.

1989-01-01

Types of 2-nitroimidazoles and 3-nitro-1,2,4-triazoles bearing one or two fluorine atoms on their side chains were synthesized to evaluate their physicochemical properties, radiosensitizing effects, and toxicity. The reduction potential of the compounds containing one fluorine was similar to that of misonidazole (MISO), whereas that of the difluorinated compounds was slightly higher. Both mono- and difluorinated compounds had an in vitro sensitizing activity comparable to or slightly higher than that of MISO. The fluorinated 3-nitrotriazoles were almost as efficient as the 2-nitroimidazoles with the same substituent. In vivo, some of the compounds were up to twice more efficient than MISO, whereas others were as efficient as MISO. Toxicity in terms of LD50/7 in mice was quite variable depending on the side-chain structure; the amide derivatives were less toxic than MISO, whereas the alcohol and ether derivatives were more toxic. In view of the radiosensitizing effect and toxicity in vivo, at least one compound, KU-2285 (a 2-nitroimidazole with an N1-substituent of: CH2CF2CONHCH2CH2OH) has been found to be as useful a hypoxic cell sensitizer as SR-2508

Experimental research on combustion fluorine retention using calcium-based sorbents during coal combustion (II)

Energy Technology Data Exchange (ETDEWEB)

Qi, Q.; Ma, X.; Liu, J.; Wu, X.; Zhou, J.; Cen, K. [Liaoning Technical University, Fuxin (China). College of Resource and Environment Engineering

2008-12-15

Fluoride pollution produced by coal burning can be controlled with the calcium-based sorbent combustion fluorine technique in which calcium-based sorbents are mixed with the coal or sprayed into the combustion chamber. In a fixed bed tube furnace combustion experiment using one calcium-based natural mineral, limestone and one calcium-based building material, it was shown that the calcium-based sorbent particle grain size and pore structure have a big influence on the combustion fluorine retention effect. Reducing the calcium-based sorbent particle grain size and improving the calcium sorbent structure characteristics at very high temperature to enhance the fluorine retention effect is the important approach to the fluorine retention agent development. 8 refs., 1 fig., 5 tabs.

Supercritical temperature synthesis of fluorine-doped VO2(M) nanoparticle with improved thermochromic property

Science.gov (United States)

Riapanitra, Anung; Asakura, Yusuke; Cao, Wenbin; Noda, Yasuto; Yin, Shu

2018-06-01

Fluorine-doped VO2(M) nanoparticles have been successfully synthesized using the hydrothermal method at a supercritical temperature of 490 °C. The pristine VO2(M) has the critical phase transformation temperature of 64 °C. The morphology and homogeneity of the monoclinic structure VO2(M) were adopted by the fluorine-doped system. The obtained particle size of the samples is smaller at the higher concentration of anion doping. The best reduction of critical temperature was achieved by fluorine doping of 0.13% up to 48 °C. The thin films of the fluorine-doped VO2(M) showed pronounced thermochromic property and therefore are suitable for smart window applications.

Development of superhydrophobic fabrics by surface fluorination and formation of CNT-induced roughness

Directory of Open Access Journals (Sweden)

Myoung Hee Shim

2015-03-01

Full Text Available Superhydrophobictextile material having self-cleaning function was developed by employing carbon nanotubes (CNTs and water-repellent agents.Hydrophobic fabrics were prepared on 100% polyester woven fabrics withvarious yarn diameters and yarn types. The wetting behavior of fabrics withdifferent treatments was compared for: siloxanerepellent, fluorocarbon repellent, and CNT added fluorocarbon repellent. Drawn textured yarn (DTY fabrics exhibited higher contactangle (CA than filament yarn fabrics due to the larger surface roughness contributed by the textured yarn. Fabrics treated with fluorocarbon presentedlarger CA and lower shedding angle than those treated with siloxane,because of the lower surface energy of fluorocarbon repellent. Specimens madeof 50 denier DTY and treated with CNT-Teflon AF® showed the mostsuperhydrophobic characteristics in the study, producing the static contactangle>150° and the shedding angle<15°. CNT on fabric surface contributedto the nano-scale surface roughness to hold the air traps like papillae oflotus leaf, giving superhydrophobic characteristics.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5762

Fluorine determination in human and animal bones by particle-induced gamma-ray emission

International Nuclear Information System (INIS)

Sastri, Chaturvedula S.; Hoffmann, Peter; Ortner, Hugo M.; Iyengar, Venkatesh; Blondiaux, Gilbert; Tessier, Yves; Petri, Hermann; Aras, Namik K.; Zaichick, Vladimir

2002-01-01

Fluorine was determined in the iliac crest bones of patients and in ribs collected from postmortem investigations by particle-induced gamma-ray emission based on the 19 F(p,pγ) 19 F reaction, using 20/2.5 MeV protons. The results indicate that for 68% of the human samples the F concentration is in the range 500-1999 μg g -1 . For comparison purposes fluorine was also determined in some animal bones; in some animal tissues lateral profiles of fluorine were measured. (abstract)

Description of an engineering-scale facility for uranium fluorination studies

International Nuclear Information System (INIS)

Yagi, Eiji; Saito, Shinichi; Horiuchi, Masato

1976-03-01

In the research program of power reactor fuel reprocessing by fluoride volatility process, the engineering facility was constructed to establish the techniques of handling kilogram quantities of fluorine and uranium hexafluoride and to obtain engineering data on the uranium fluidized-bed oxidation and fluorination. This facility is designed for a capacity of 5 kg per batch. Descriptions on the facility and equipment are given, including design philosophy, safety and its analysis. (auth.)

Effect of surface energy on powder compactibility.

Science.gov (United States)

Fichtner, Frauke; Mahlin, Denny; Welch, Ken; Gaisford, Simon; Alderborn, Göran

2008-12-01

The influence of surface energy on the compactibility of lactose particles has been investigated. Three powders were prepared by spray drying lactose solutions without or with low proportions of the surfactant polysorbate 80. Various powder and tablet characterisation procedures were applied. The surface energy of the powders was characterized by Inverse Gas Chromatography and the compressibility of the powders was described by the relationship between tablet porosity and compression pressure. The compactibility of the powders was analyzed by studying the evolution of tablet tensile strength with increasing compaction pressure and porosity. All powders were amorphous and similar in particle size, shape, and surface area. The compressibility of the powders and the microstructure of the formed tablets were equal. However, the compactibility and dispersive surface energy was dependent of the composition of the powders. The decrease in tablet strength correlated to the decrease in powder surface energy at constant tablet porosities. This supports the idea that tablet strength is controlled by formation of intermolecular forces over the areas of contact between the particles and that the strength of these bonding forces is controlled by surface energy which, in turn, can be altered by the presence of surfactants.

Synthesis and characterization of fluorine compounds

International Nuclear Information System (INIS)

Martinez Carrillo, M.

1991-01-01

The ( 18 F) D-glucose, 2-deoxy fluorine ( 18 FDG) is a radio pharmaceutic that is used in nuclear medicine it is utilized mainly in the glucose metabolism. It allows recently to observe the tumors accumulation and growing. The obtention of this radio pharmaceutic can realize by a nucleophilic or electrophilic process through the use of different fluorinated agents obtained as intermediates for introducing the 18 F radionuclide in a final step of synthesis. The first methods already has been studied in the National Institute of Nuclear Research. The second one which is based this work and it was realized through the reaction of acetyl hypo fluorite (CH 3 COOF) with tri acetyl glucal (TAG) in turn they require the obtention of several fluorated compounds that they serve as intermediates for their obtention so that objective of this work was to find the adequate technique for the obtention of anhydride hydrofluoric acid (HF), KF.2 HF and elemental fluorine so as the design and construction of the systems and equipment used for carry out each one of the reactions. Moreover it was designed the system that will be used for the obtention of acetyl hypo fluoride and the synthesis of composite tetraacetilide 3,4,6 tri-D-glucopyranosil fluoride (TAG-F) for that finally by hydrolysis it was obtained the 2-deoxy fluoride-D-glucose (TAG) in inactive. In this system were realized several preliminary tests. The results are showed in the content of this work also the techniques for compounds characterization were given. (Author)

Concavity Theorems for Energy Surfaces

OpenAIRE

Giraud, B. G.; Karataglidis, S.

2011-01-01

Concavity properties prevent the existence of significant landscapes in energy surfaces obtained by strict constrained energy minimizations. The inherent contradiction is due to fluctuations of collective coordinates. A solution to those fluctuations is given.

75 FR 74773 - Mandatory Reporting of Greenhouse Gases: Additional Sources of Fluorinated GHGs

Science.gov (United States)

2010-12-01

...-mechanical systems (MEMS) manufacturing facilities. Fluorinated Gas Production....... 325120 Industrial gases... of Industrial Greenhouse Gases. Electrical Equipment Use General Stationary Fuel Combustion. Imports and Exports of Fluorinated Suppliers of Industrial Greenhouse GHGs Inside Pre-charged Equipment Gases...

The influence of fluorine on phase relations and REE enrichment in alkaline magmas

Science.gov (United States)

Beard, C. D.; van Hinsberg, V.; Stix, J.; Wilke, M.

2017-12-01

Fluorine is a minor element in most magmas, but higher concentrations to wt% levels have been reported in alkaline systems, including those which host economic deposits of REE + HFSE1. Despite low abundance in most natural melts, fluorine has received great attention from the experimental community because it has a strong influence on melt structure, lowering melting points and drastically reducing viscosity. The effect of fluorine on element speciation has important implications for phase relations and the partitioning of trace elements between minerals and melts, thus metal enrichment processes in alkaline magmas. We have experimentally investigated the impact of fluorine on phase relations and partitioning of rare metals, the REE in particular, in evolved alkaline melts. Synthetic glasses of tephriphonolite to phonolite composition were doped with a wide range of elements at trace levels, and fluorine contents were varied from fluorine-free to 2.5 wt%. Experiments were performed water-saturated in an internally heated pressure vessel at 200 MPa with log fO2 at ca. QFM+1, which represents the intrinsic redox conditions of the setup. Charges were heated to super-liquidus conditions for 16 hours, cooled slowly (1˚C/min) to run temperature and subsequently equilibrated for at least 40 hours. Run products were analysed by EPMA and LA-ICP-MS. The experiments produce an equilibrium assemblage of sodic pyroxene, biotite, Fe-oxide, melt, fluid, ±K-feldspar, ±titanite, ±fluorite. Addition of fluorine markedly increases the mode of biotite, which initially buffers melt F content at low levels (< 0.2 wt%). Only in experiments with more than 0.6 wt% F do we observe a significant increase in the melt F-content. Here, fluorine decreases pyroxene/melt partitioning coefficients equally for all REE where pyroxene composition and P-T conditions are equivalent (ca. 1/2 with 0.6% F). We suggest that the formation of REE-F complexes in the melt2 lowers the availability of metals

Analysis of anti-condensation mechanism on superhydrophobic anodic aluminum oxide surface

International Nuclear Information System (INIS)

Wu, Yanpeng; Zhang, Chaoying

2013-01-01

Wetting theory about superhydrophobic surfaces reveals that hydrophobicity of surfaces has great relationship with surface roughness and surface free energy. Adopt electrochemical plus fluorine silane modified method to prepare superhydrophobic surface on anodic aluminum oxide surface, which not only enhances surface roughness, but also reduces surface free energy, even the static contact angle can reach 159.2° and anti-condensation is authenticated. Based on the experimental findings, analyze the reason of anti-condensation on superhydrophobic surfaces: one is that the density of droplets formed on superhydrophobic surfaces is low and the number of droplets is little; the other is bigger static contact angle and smaller rolling angle on superhydrophobic surfaces make droplets easy to detach on smaller tilt angle. This research can solve some condensation problems of equipment using in HVAC systems, such as heat exchangers in air conditioning system, cold radiation boards, air supply outlets, and so on. Highlights: • Prepare superhydrophobic surface on anodic aluminum oxide surface. • Analyze the reason of anti-condensation on superhydrophobic surfaces. • The density of droplets formed on superhydrophobic surfaces is low. • Droplets on superhydrophobic surfaces are easy to detach. • This research can solve some problems of equipment using in HVAC systems

Collisions of benzene and buckminsterfullerene at fluorinated and non-fluorinated self-assembled monolayer films

International Nuclear Information System (INIS)

Wysocki, V.H.; Ding, H.M.; Kane, T.E.; Somogyi, A.; Callahan, J.H.

1992-01-01

It has been illustrated that a variety of analytically-useful processes occur upon low-energy (eV) collisions of mass-selected polyatomic ions with a surface. These include surface induced dissociation, reactive collisions of projectile ions with surface adsorbates, and chemical sputtering. The goal of the research described here is to investigate the ion-surface chemistry that is detected when C 6 H 6 + , C 6 D 6 + , C 6 H 5 F + , C 60 + , and C 60 ++ collide with a well-characterized surface at collision energies of 10-100 eV

Accumulation of fluorine in the leaves of trees and shrubs growing in industrial territories

Energy Technology Data Exchange (ETDEWEB)

Asadov, G G; Alekperov, S A; Mamedov, G G

1977-01-01

Measurements were made to compare the concentration of fluorine in various plants in the vicinity of an aluminum plant, a glass plant and a chemical plant. The accumulation of fluorine was higher in the leaves of plants near the aluminum and glass industry than in the vicinity of another chemical industry. The fluorine concentration was found to be highest in spring. Pines and poplars were the most sensitive of the species tested.

Multiple receptor conformers based molecular docking study of fluorine enhanced ethionamide with mycobacterium enoyl ACP reductase (InhA).

Science.gov (United States)

Khan, Akib Mahmud; Shawon, Jakaria; Halim, Mohammad A

2017-10-01

A major limitation in current molecular docking method is that of failure to account for receptor flexibility. Herein we report multiple receptor conformers based molecular docking as a practical alternative to account for the receptor flexibility. Multiple (forty) conformers of Mycobacterium Enoyl ACP Reductase (InhA) are generated from Molecular Dynamics simulation and twenty crystallographic structures of InhA bound to different inhibitors are obtained from the Protein Data Bank. Fluorine directed modifications are performed to currently available anti-tuberculosis drug ethionamide. The modified drugs are optimized using B3LYP 6-31G (d,p) level of theory. Dipole moment, frontier orbital gap and thermodynamical properties such as electronic energy, enthalpy and Gibbs free energy of these optimized drugs are investigated. These drugs are subsequently docked against the conformers of InhA. Molecular docking against multiple InhA conformations show variation in ligand binding affinity and suggest that Ser94, Gly96, Lys165 and Ile194 amino acids play critical role on strong drug-InhA interaction. Modified drug N1 showed greater binding affinity compared to EN in most conformations. Structure of PDB ID: 2NSD and snapshot conformer at 5.5ns show most favorable binding with N1 compared to other conformers. Fluorine participates in forming fluorine bonds and contributes significantly in increasing binding affinity. Our study reveal that addition of trifluoromethyl group explicitly shows promise in improving thermodynamic properties and in enhancing hydrogen bonding and non-bonded interactions. Molecular dynamics (MD) simulation show that EN and N1 remained in the binding pocket similar to the docked pose of EN-InhA and E1-InhA complexes and also suggested that InhA binds to its inhibitor in inhibitor-induced folding manner. ADMET calculations predict modified drugs to have improved pharmacokinetic properties. Our study concludes that multiple receptor conformers based

SURFACE ENERGY BALANCE OVER ORANGE ORCHARD USING SURFACE RENEWAL ANALYSIS

Directory of Open Access Journals (Sweden)

Salvatore Barbagallo

2009-12-01

Full Text Available Reliable estimation of surface sensible and latent heat flux is the most important process to appraise energy and mass exchange among atmosphere and biosphere. In this study the surface energy fluxes were measured over an irrigated orange orchard during 2005-2008 monitoring periods using a Surface Renewal- Energy Balance approach. The experimental area is located in a representative orchard growing area of eastern Sicily (Italy. The performance of Surface Renewal (SR analysis for estimating sensible heat flux (H was analysed and evaluated in terms of correlation with H fluxes from the eddy covariance (EC method. Study revealed that the mean available energy (RN- G and latent heat flux (LE were of about 300 W m-2 and 237 W m-2, respectively, during dry periods and unstable-case atmospheric conditions. The estimated crop coefficient Kc values for the orchard crop averaged close to 0.80, which is considerably higher than previous FAO studies that found the value to be 0.65 for citrus with 70% of ground cover. The intercepted photosynthetically active radiation (LI PAR by the crop was measured and relationships between LAI and crop coefficient (Kc were established.

Structure of a putative fluorinated natural product from Streptomyces sp. TC1.

Science.gov (United States)

Aldemir, Hülya; Kohlhepp, Stefanie V; Gulder, Tanja; Gulder, Tobias A M

2014-11-26

Fluorine-containing natural products are extremely rare. The recent report on the isolation and biological activity of the bacterial secondary metabolite 3-(3,5-di-tert-butyl-4-fluorophenyl)propionic acid was thus highly remarkable. The compound contained the first aromatic fluorine substituent known to date in any natural product. The promise to discover an enzyme capable of aromatic fluorination in the producing strain Streptomyces sp. TC1 prompted our immediate interest. A close inspection of the originally reported analytical data of the fluoro metabolite revealed inconsistencies that triggered us to validate the reported structure. The results of these efforts are presented in this communication.

Fluorine dynamics in BaF2 superionic conductors investigated by NMR

International Nuclear Information System (INIS)

Gumann, Patryk

2008-01-01

In this work the dynamics of fluorine in solid-state electrolytes having BaF 2 -structure was investigated using three different NMR-methods: field cycling relaxometry, lineshape analysis, and static field gradient NMR. For this purpose a pure BaF 2 crystal, as well as crystals doped with trivalent impurities (LaF 3 ), were studied as a function of temperature. Using MAS NMR it was possible to identify two lines in Ba 0.9 La 0.1 F 2.1 having different chemical shift, and to refer them to the modified crystal structure. On this basis a model for the fluorine lineshape has been developed, taking into account three motional processes characterized by their correlation times. It includes jump diffusion of the fluorine ions among equivalent sites within two crystallographically distinct sublattices, and inter-lattice exchange processes. By measuring frequency and temperature-dependent spin lattice relaxation times, it was possible to gain information about fluorine dynamics on microscopic length scales. An attempt was also made to analyze the data for pure BaF 2 and low admixture concentration samples with a non-exponential correlation function. (orig.)

Surface free energy of alkali and transition metal nanoparticles

International Nuclear Information System (INIS)

Aqra, Fathi; Ayyad, Ahmed

2014-01-01

Graphical abstract: Size dependent surface free energy of spherical, cubic and disk Au nanoparticles. - Highlights: • A model to account for the surface free energy of metallic nanoparticles is described. • The model requires only the cohesive energy of the nanoparticle. • The surface free energy of a number of metallic nanoparticles has been calculated, and the obtained values agree well with existing data. • Surface energy falls down very fast when the number of atoms is less than hundred. • The model is applicable to any metallic nanoparticle. - Abstract: This paper addresses an interesting issue on the surface free energy of metallic nanoparticles as compared to the bulk material. Starting from a previously reported equation, a theoretical model, that involves a specific term for calculating the cohesive energy of nanoparticle, is established in a view to describe the behavior of surface free energy of metallic nanoparticles (using different shapes of particle: sphere, cube and disc). The results indicate that the behavior of surface energy is very appropriate for spherical nanoparticle, and thus, it is the most realistic shape of a nanoparticle. The surface energy of copper, silver, gold, platinum, tungsten, molybdenum, tantalum, paladium and alkali metallic nanoparticles is only prominent in the nanoscale size, and it decreases with the decrease of nanoparticle size. Thus, the surface free energy plays a more important role in determining the properties of nanoparticles than in bulk materials. It differs from shape to another, and falls down as the number of atoms (nanoparticle size) decreases. In the case of spherical nanoparticles, the onset of the sharp decrease in surface energy is observed at about 110 atom. A decrease of 16% and 45% in surface energy is found by moving from bulk to 110 atom and from bulk to 5 atom, respectively. The predictions are consistent with the reported data

Fluorine: A key enabling element in the nuclear fuel cycle

OpenAIRE

Crouse, P.L.

2015-01-01

Fluorine - in the form of hydrofluoric acid, anhydrous hydrogen fluoride, elemental gaseous fluorine, fluoropolymers, volatile inorganic fluorides, and more - has played, and still plays, a major role in the nuclear industry. In order to enrich uranium, the metal has to be in the gaseous state. While more exotic methods are known, the standard and most cost-competitive way of achieving this is by means of uranium hexafluoride (UF6). This compound sublimates at low temperatures, and the vapour...

Enhanced performance of dye-sensitized solar cells using gold nanoparticles modified fluorine tin oxide electrodes

International Nuclear Information System (INIS)

Zhang Dingwen; Shen Jie; Huang Sumei; Wang Milton; Brolo, Alexandre G; Li Xiaodong

2013-01-01

We have investigated plasmon-assisted energy conversion in dye-sensitized solar cells (DSCs) applying gold nanoparticles (NPs) modified fluorine tin oxide (FTO) electrodes. A series of Au NPs with different sizes (15-80 nm) were synthesized and immobilized onto FTO glass slides. Photoanodes were prepared on these Au modified FTO substrates using P25 TiO 2 powders and by the screen-printing method. The size effects of Au NPs on the photovoltaic performance of the formed DSCs were investigated systematically. Structural and photoelectrochemical properties of the formed photoanodes were examined by field emission scanning electron microscopy and electrochemical impedance spectroscopy. It was found that the energy conversion efficiency of the DSC was highly dependent on the Au particle size. When the particle size was not greater than 60 nm, the DSC based on the Au NP-FTO composite electrode showed a higher short-circuit current density and better photovoltaic (PV) performance than the cell based on the bare FTO. The best cell was achieved using 25 nm sized Au NPs modified FTO. It exhibited a conversion efficiency of 6.69%, which was 15% higher than that of DSCs without Au NPs. The related PV performance enhancement mechanisms, photoelectrochemical processes and surface-plasmon resonances in DSCs with Au nanostructures are analysed and discussed.

Study of the elimination of fluorine from drinking water using adsorbent materials

International Nuclear Information System (INIS)

Flores de la Torre, J.A.; Badillo A, V.E.; Badillo A, V.; Lopez D, F.A.

2004-01-01

With the purpose of diminishing the levels of fluorine in the water in certain areas geographical of the country, the interaction of the fluorine is studied, with a Mexican natural clay, called kaolinite and a synthetic apatite called hydroxyapatite. Due to the discharges concentrations of this element in waters of human consumption cause fluorosis dental and osseous, it is important to propose adsorbent materials able to diminish those elevated concentrations of fluorine. In this investigation work the retention of the fluorine is studied in mineral phases using the tracer radioactive 8 F. This retention is expressed in terms of the fixed percent of 18 F, in a natural kaolinite in solution of NaCl 0.01 M, and in a synthetic hydroxyapatite setting in contact with a solution of NaF 0.01 M and a solution of NaH 2 PO 4 0.01 M, all in function of the value of the p H of the solution. The results demonstrate that the influence of the p H is remarkable in the retention of the fluoride in both minerals, demonstrating that the hydroxyapatite (calcium phosphate) it retains in a lot of bigger proportion to the fluorine that the kaolinite (aluminosilicate), all this to values of acid p H, diminishing as the value of the p H increases. (Author)

Adhesive interactions of geckos with wet and dry fluoropolymer substrates.

Science.gov (United States)

Stark, Alyssa Y; Dryden, Daniel M; Olderman, Jeffrey; Peterson, Kelly A; Niewiarowski, Peter H; French, Roger H; Dhinojwala, Ali

2015-07-06

Fluorinated substrates like Teflon® (poly(tetrafluoroethylene); PTFE) are well known for their role in creating non-stick surfaces. We showed previously that even geckos, which can stick to most surfaces under a wide variety of conditions, slip on PTFE. Surprisingly, however, geckos can stick reasonably well to PTFE if it is wet. In an effort to explain this effect, we have turned our attention to the role of substrate surface energy and roughness when shear adhesion occurs in media other than air. In this study, we removed the roughness component inherent to commercially available PTFE and tested geckos on relatively smooth wet and dry fluoropolymer substrates. We found that roughness had very little effect on shear adhesion in air or in water and that the level of fluorination was most important for shear adhesion, particularly in air. Surface energy calculations of the two fluorinated substrates and one control substrate using the Tabor-Winterton approximation and the Young-Dupré equation were used to determine the interfacial energy of the substrates. Using these interfacial energies we estimated the ratio of wet and dry normal adhesion for geckos clinging to the three substrates. Consistent with the results for rough PTFE, our predictions show a qualitative trend in shear adhesion based on fluorination, and the quantitative experimental differences highlight the unusually low shear adhesion of geckos on dry smooth fluorinated substrates, which is not captured by surface energy calculations. Our work has implications for bioinspired design of synthetics that can preferentially stick in water but not in air.

(Liquid + liquid) equilibria of perfluorocarbons with fluorinated ionic liquids

International Nuclear Information System (INIS)

Martinho, S.; Araújo, J.M.M.; Rebelo, L.P.N.; Pereiro, A.B.; Marrucho, I.M.

2013-01-01

Highlights: • (Liquid + liquid) equilibria perfluorocarbons and fluorinated ionic liquids. • Non-Random Two Liquid model was successfully applied. • Thermodynamic functions that describe the solvation process were calculated. -- Abstract: In order to evaluate the feasibility of partially replace perfluorocarbons (PFCs) with fluorinated ionic liquids (FILs) in PFCs-in-water emulsions, usually used for biomedical purposes, herein the (liquid + liquid) phase equilibria of FILs containing fluorinated chains longer than four carbons with PFCs were carried out in a wide range of temperatures. With this goal in mind, two PFCs (perfluorooctane and perfluorodecalin) were selected and the (liquid + liquid) equilibria of the binary mixtures of these PFCs and FILs were studied at atmospheric pressure in a temperature range from T (293.15 to 343.15) K. For these studies, FILs containing ammonium, pyridinium and imidazolium cations and different anions with fluorocarbon alkyl chains between 4 and 8 were included. Additionally, Non-Random Two Liquid (NRTL) thermodynamic model was successfully applied to correlate the behaviour of the PFCs + FILs binary mixtures. Moreover, thermodynamic functions that describe the solvation process were calculated from the experimental data

Fluorinated graphene and hexagonal boron nitride as ALD seed layers for graphene-based van der Waals heterostructures

International Nuclear Information System (INIS)

Guo, Hongwei; Liu, Yunlong; Xu, Yang; Meng, Nan; Luo, Jikui; Wang, Hongtao; Hasan, Tawfique; Wang, Xinran; Yu, Bin

2014-01-01

Ultrathin dielectric materials prepared by atomic-layer-deposition (ALD) technology are commonly used in graphene electronics. Using the first-principles density functional theory calculations with van der Waals (vdW) interactions included, we demonstrate that single-side fluorinated graphene (SFG) and hexagonal boron nitride (h-BN) exhibit large physical adsorption energy and strong electrostatic interactions with H 2 O-based ALD precursors, indicating their potential as the ALD seed layer for dielectric growth on graphene. In graphene-SFG vdW heterostructures, graphene is n-doped after ALD precursor adsorption on the SFG surface caused by vertical intrinsic polarization of SFG. However, graphene-h-BN vdW heterostructures help preserving the intrinsic characteristics of the underlying graphene due to in-plane intrinsic polarization of h-BN. By choosing SFG or BN as the ALD seed layer on the basis of actual device design needs, the graphene vdW heterostructures may find applications in low-dimensional electronics. (paper)

Molecular Dynamics Pinpoint the Global Fluorine Effect in Balanoid Binding to PKCε and PKA.

Science.gov (United States)

Hardianto, Ari; Liu, Fei; Ranganathan, Shoba

2018-02-26

(-)-Balanol is an adenosine triphosphate mimic that inhibits protein kinase C (PKC) isozymes and cAMP-dependent protein kinase (PKA) with limited selectivity. While PKA is known as a tumor promoter, PKC isozymes can be tumor promoters or suppressors. In particular, PKCε is frequently involved in tumorigenesis and a potential target for anticancer drugs. We recently reported that stereospecific fluorination of balanol yielded a balanoid with enhanced selectivity for PKCε over other PKC isozymes and PKA, although the global fluorine effect behind the selectivity enhancement is not fully understood. Interestingly, in contrast to PKA, PKCε is more sensitive to this fluorine effect. Here we investigate the global fluorine effect on the different binding responses of PKCε and PKA to balanoids using molecular dynamics (MD) simulations. For the first time to the best of our knowledge, we found that a structurally equivalent residue in each kinase, Thr184 in PKA and Ala549 in PKCε, is essential for the different binding responses. Furthermore, the study revealed that the invariant Lys, Lys73 in PKA and Lys437 in PKCε, already known to have a crucial role in the catalytic activity of kinases, serves as the main anchor for balanol binding. Overall, while Thr184 in PKA attenuates the effect of fluorination, Ala549 permits remote response of PKCε to fluorine substitution, with implications for rational design of future balanol-based PKCε inhibitors.

Note: Loading method of molecular fluorine using x-ray induced chemistry

International Nuclear Information System (INIS)

Pravica, Michael; Sneed, Daniel; White, Melanie; Wang, Yonggang

2014-01-01

We have successfully loaded molecular fluorine into a diamond anvil cell at high pressure using the synchrotron x-ray induced decomposition of perfluorohexane (C 6 F 14 ). “White” x-ray radiation from the Advanced Photon Source was used to initiate the chemical decomposition of C 6 F 14 , which resulted in the in situ production of F 2 as verified via Raman spectroscopy. Due to the toxic nature of fluorine, this method will offer significant advantages in the ability to easily load a relatively nontoxic and inert substance into a chamber (such as a diamond anvil cell) that, when sealed with other reactants and irradiate with hard x-rays (>7 keV), releases highly reactive and toxic fluorine into the sample/reaction chamber to enable novel chemical synthesis under isolated and/or extreme conditions

Low power fluorine plasma effects on electrical reliability of AlGaN/GaN high electron mobility transistor

International Nuclear Information System (INIS)

Yang Ling; Zhou Xiao-Wei; Ma Xiao-Hua; Lv Ling; Zhang Jin-Cheng; Hao Yue; Cao Yan-Rong

2017-01-01

The new electrical degradation phenomenon of the AlGaN/GaN high electron mobility transistor (HEMT) treated by low power fluorine plasma is discovered. The saturated current, on-resistance, threshold voltage, gate leakage and breakdown voltage show that each experiences a significant change in a short time stress, and then keeps unchangeable. The migration phenomenon of fluorine ions is further validated by the electron redistribution and breakdown voltage enhancement after off-state stress. These results suggest that the low power fluorine implant ion stays in an unstable state. It causes the electrical properties of AlGaN/GaN HEMT to present early degradation. A new migration and degradation mechanism of the low power fluorine implant ion under the off-stress electrical stress is proposed. The low power fluorine ions would drift at the beginning of the off-state stress, and then accumulate between gate and drain nearby the gate side. Due to the strong electronegativity of fluorine, the accumulation of the front fluorine ions would prevent the subsequent fluorine ions from drifting, thereby alleviating further the degradation of AlGaN/GaN HEMT electrical properties. (paper)

Fluorine Abundances of AGB Stars in Stellar Clusters

Science.gov (United States)

Hren, A.; Lebzelter, T.; Aringer, B.; Hinkle, K. H.; Nowotny, W.

2015-08-01

We have measured the abundance of fluorine, [F/Fe], in a number of AGB stars in stellar clusters have correlated the results with their C/O ratios. This allows us to investigate the change in the fluorine abundance along the evolution on the giant branch. The target list includes primarily O-rich stars in three LMC globular clusters - NGC 1806, NGC 1846 and NGC 1978 - as well as Rup 106 and 47 Tuc in our Galaxy. The observational data were obtained with the PHOENIX spectrograph, and the COMA code was used for modelling the synthetic spectra. Within individual clusters, we find consistent [F/Fe] values at similar C/O for most of our target stars.

Preparation and characterization of very pure zirconium tetrafluoride. Application to fluorinated glass

International Nuclear Information System (INIS)

Bridenne, M.

1986-12-01

The synthesis of anhydrous and very pure zirconium tetrafluoride from zirconium tetraborohydride is studied. Zr F 4 is used for fabrication of fluorozirconate glass. Zr (BH 4 ) 4 is purified by sublimation. Two fluorinating agents F 2 and anhydrous HF are used for fluorination. The apparatus is made of fluorinated polymers and a Kel-F prototype reactor was realized. 20 g of Zr F 4 are obtained in 44 hrs with a yield of 88 %. Purity is characterized by chemical analysis (atomique absorption spectroscopy and spark mass spectroscopy) and absorption of an optical fiber made of zirconium tetrafluoride. Cr, Ni, Co and Cu content is lower than 0.1 ppm. Possibility of pilot scale production is discussed [fr

Energy exchange in thermal energy atom-surface scattering: impulsive models

International Nuclear Information System (INIS)

Barker, J.A.; Auerbach, D.J.

1979-01-01

Energy exchange in thermal energy atom surface collisions is studied using impulsive ('hard cube' and 'hard sphere') models. Both models reproduce the observed nearly linear relation between outgoing and incoming energies. In addition, the hard-sphere model accounts for the widths of the outcoming energy distributions. (Auth.)

Solar energy converter using surface plasma waves

Science.gov (United States)

Anderson, L. M. (Inventor)

1984-01-01

Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

Critical assessment of Pt surface energy - An atomistic study

Science.gov (United States)

Kim, Jin-Soo; Seol, Donghyuk; Lee, Byeong-Joo

2018-04-01

Despite the fact that surface energy is a fundamental quantity in understanding surface structure of nanoparticle, the results of experimental measurements and theoretical calculations for the surface energy of pure Pt show a wide range of scattering. It is necessary to further ensure the surface energy of Pt to find the equilibrium shape and atomic configuration in Pt bimetallic nanoparticles accurately. In this article, we critically assess and optimize the Pt surface energy using a semi-empirical atomistic approach based on the second nearest-neighbor modified embedded-atom method interatomic potential. That is, the interatomic potential of pure Pt was adjusted in a way that the surface segregation tendency in a wide range of Pt binary alloys is reproduced in accordance with experimental information. The final optimized Pt surface energy (mJ/m2) is 2036 for (100) surface, 2106 for (110) surface, and 1502 for (111) surface. The potential can be utilized to find the equilibrium shape and atomic configuration of Pt bimetallic nanoparticles more accurately.

RELATIONSHIP BETWEEN FOAMING BEHAVIOR AND SURFACE ENERGY OF ASPHALT BINDER

Directory of Open Access Journals (Sweden)

Jian-ping Xu

2017-12-01

Full Text Available To solve the problem of insufficiency in microscopic performance of foamed asphalt binder, surface energy theory was utilized to analyze the foaming behavior and wettability of asphalt binder. Based on the surface energy theory, the Wilhelmy plate method and universal sorption device method were employed to measure the surface energy components of asphalt binders and aggregates, respectively. Combined with the traditional evaluation indictor for foamed asphalt, the relationship between the foaming property and surface energy of asphalt binder was analyzed. According to the surface energy components, the wettability of asphalt binder to aggregate was calculated to verify the performance of foamed asphalt mixture. Results indicate that the foaming behavior of asphalt will be influenced by surface energy, which will increase with the decline of surface energy. In addition, the surface energy of asphalt binder significantly influences the wettability of asphalt binder to aggregates. Meanwhile, there is an inversely proportional relationship between surface energy of asphalt binder and wettability. Therefore, it can be demonstrated that surface energy is a good indictor which can be used to evaluate the foaming behavior of the asphalt binder. And it is suggested to choose the asphalt binder with lower surface energy in the process of design of foamed asphalt mixture.

[Experimental study on fas expression of spermatogenic cell in male rats induced by fluorine].

Science.gov (United States)

Xu, Rui; Shang, Weichao; Liu, Jianmin; Cheng, Xuemin; Ba, Yue; Huang, Hui; Cui, Liuxin

2010-05-01

To research the effect of fluorine on the expression of Fas protein, then study the mechanism of male reproductive toxicity induced by fluoride on molecular level. Thirty Wistar male rats were divided into control group, low-dose group and high-dose group. The NaF dosage for every group were 0,2 and 4g/L. The content of NaF in testis was measured by using fluorine selective electrode. Changes of testosterone and Fas protein were observed using the methods of radioimmunoassay, in situ hybridization. In addition, we observed the quality of spermatozoa. The testis fluoride content of two fluorine treatment groups were higher than that of control group (P Fluorin could reduce the level of serum testosterone, then activated the Fas/FasL system, which caused damage to the reprodutive system.

Magnetic study of solid uranium-fluorine complexes; Contribution a l'etude magnetique de composes fluores solides de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Dianoux, A.J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-06-01

A study of the magnetic susceptibility of uranium V fluorine complexes and of the magnetic resonance of fluorine atoms in uranium VI fluorine complexes has made it possible to put forward a structural model for these compounds for which it is impossible, because of the lack of suitable single crystals for X-ray diffraction work, to deduce the exact position of the fluorine atoms. It is shown that it is difficult to interpret the paramagnetism of uranium fluorides, because the uranium ions are in low-symmetry sites. A theoretical study of the magnetism of the U{sup V} ion in complex fluorides of the type M{sub 3}UF{sub 8} (M = NH{sub 4}, Na, Rb, Cs) leads to an interpretation based on a trigonal deformation of the eight fluorine atom structure surrounding the uranium atom. By applying a Hamiltonian spin formalism and making a systematic use of group theory, it is possible to present the susceptibility calculations very concisely. Study of the resonance and of the relaxation of the fluorine atoms in powdered uranium VI complex fluorides suggests a structural model in the case of NaUF{sub 7}. It is shown that the shape of the magnetic resonance absorption lines is strongly affected by the presence of large anisotropic chemical shifts. In the model proposed here, six fluorine atoms are linked to the uranium, atom by strongly covalent bonds in a deformed UF{sub 6} octahedral structure; the seventh fluorine atom remains ionic. The occurrence of a rotational movement of the octahedron is confirmed by a study of the longitudinal relaxation of the fluorine atoms, the activation energy being 0.46 eV. (author) [French] L'etude de la susceptibilite magnetique de complexes fluores d'uranium V et la resonance magnetique des fluors dans des complexes fluores d'uranium VI permettent de proposer un modele structural pour ces composes, ou la diffraction des rayons X, en l'absence de monocristaux convenables, est incapable de preciser la position des atomes de