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Sample records for selective electrochemical fluorination

  1. 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.

  2. 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.

  3. Electrochemical stability and transformations of fluorinated poly(2,6-dimethyl-1,4-phenylene oxide)

    NARCIS (Netherlands)

    Pud, A.A.; Rogalsky, S.P.; Ghapoval, G.S.; Kharitonov, A.P.; Kemperman, Antonius J.B.

    2000-01-01

    Fluorination of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) leads to narrowing of its window of electrochemical stability in a cathodic range of potentials. It is found this is connected with appearance of both perfluorinated and incompletely fluorinated units in the polymer. The former units are

  4. 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.

  5. 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.

  6. 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

    Fluorine compounds are essential in numerous chemical and manufacturing processes. Fluorspar is the commercial name for fluorite (isometric CaF2), which is the only fluorine mineral that is mined on a large scale. Fluorspar is used directly as a fluxing material and as an additive in different manufacturing processes. It is the source of fluorine in the production of hydrogen fluoride or hydrofluoric acid, which is used as the feedstock for numerous organic and inorganic chemical compounds.The United States was the world’s leading producer of fluorspar until the mid-1950s. In the mid-1970s, the U.S. fluorspar mining industry began to decline because of foreign competition. By 1982, there was essentially only a single U.S. producer left, and that company ceased mining in 1996. Consumption of fluorspar in the United States peaked in the early 1970s, which was also the peak period of U.S. steel production. Since then, U.S. fluorspar consumption has decreased substantially; the United States has nonetheless increased its imports of downstream fluorine compounds, such as, in order of tonnage imported, hydrofluoric acid, aluminum fluoride, and cryolite. This combination of no U.S. production (until recently) and high levels of consumption has made the United States the world’s leading fluorspar-importing country, in all its various forms.The number of fluorspar-exporting countries has decreased substantially in recent decades, and, as a result, the United States has become dependent on just a few countries to supply its needs. In 2013, the United States imported the majority of its fluorspar from three countries, which were, in descending order of the amount imported, Mexico, China, and South Africa.Geologically, in igneous systems, fluorine is one of a number of elements that are “incompatible.” These incompatible elements become concentrated in the residual magma while the common silicates crystallize upon magma ascent and cooling, leading to relatively high

  7. Electrochemical fluorination of La(2)CuO(4): a mild "chimie douce" route to superconducting oxyfluoride materials.

    Science.gov (United States)

    Delville, M H; Barbut, D; Wattiaux, A; Bassat, J M; Ménétrier, M; Labrugère, C; Grenier, J C; Etourneau, J

    2009-08-17

    The fluorination of La(2)CuO(4) was achieved for the first time under normal conditions of pressure and temperature (1 MPa and 298 K) via electrochemical insertion in organic fluorinated electrolytes and led to lanthanum oxyfluorides of general formula La(2)CuO(4)F(x). Analyses showed that, underneath a very thin layer of LaF(3) (a few atomic layers), fluorine is effectively inserted in the material's structure. The fluorination strongly modifies the lanthanum environment, whereas very little modification is observed on copper, suggesting an insertion in the La(2)O(2) blocks of the structure. In all cases, fluorine insertion breaks the translation symmetry and introduces a long-distance disorder, as shown by electron spin resonance. These results highlight the efficiency of electrochemistry as a new "chimie douce" type fluorination technique for solid-state materials. Performed at room temperature, it additionally does not require any specific experimental care. The choice of the electrolytic medium is crucial with regard to the fluorine insertion rate as well as the material deterioration. Successful application of this technique to the well-known La(2)CuO(4) material provides a basis for further syntheses from other oxides.

  8. Electrochemical decomposition of fluorinated wetting agents in plating industry waste water.

    Science.gov (United States)

    Fath, Andreas; Sacher, Frank; McCaskie, John E

    2016-01-01

    Electrochemical decomposition of fluorinated surfactants (PFAS, perfluorinated alkyl substances) used in the plating industry was analyzed and the decomposition process parameters optimized at the laboratory scale and production scale of a 500-liter reactor using lead electrodes. The method and system was successfully demonstrated under production conditions to treat PFAS) with up to 99% efficiency in the concentration range of 1,000-20,000 μg/l (1 ppm-20 ppm). The treatment also reduced hexavalent chromium (Cr(6+)) ions to trivalent chromium (Cr(3+)) ions in the wastewater. If the PFAS-containing wastewater is mixed with other wastewater streams, specifically from nickel plating drag out solution or when pH values >5, the treatment process is ineffective. For the short chain PFAS, (perfluorobutylsulfonate) the process was less efficient than C6-C8 PFAS. The process is automated and has safety procedures and controls to prevent hazards. The PFAS were decomposed to hydrogen fluoride (HF) under the strong acid electrochemical operating conditions. Analytical tests showed no evidence of organic waste products remaining from the process. Conventional alternative PFAS removal systems were tested on the waste streams and compared with each other and with the-E-destruct (electrochemical oxidation) process. For example, ion exchange resin (IX resin) treatment of wastewater to complex and remove PFAS was found to be seven times more efficient when compared to the conventional activated carbon absorption (C-treat) process. However, the E-destruct process is higher in capacity, exhibits longer service life and lower operating costs than either IX or C-treat methods for elimination of PFAS from these electroplating waste streams.

  9. Selective, electrochemical etching of a semiconductor

    Science.gov (United States)

    Dahal, Rajendra P.; Bhat, Ishwara B.; Chow, Tat-Sing

    2018-03-20

    Methods for facilitating fabricating semiconductor structures are provided which include: providing a multilayer structure including a semiconductor layer, the semiconductor layer including a dopant and having an increased conductivity; selectively increasing, using electrochemical processing, porosity of the semiconductor layer, at least in part, the selectively increasing porosity utilizing the increased conductivity of the semiconductor layer; and removing, at least in part, the semiconductor layer with the selectively increased porosity from the multilayer structure. By way of example, the selectively increasing porosity may include selectively, anodically oxidizing, at least in part, the semiconductor layer of the multilayer structure.

  10. New Transparent Laser-Drilled Fluorine-doped Tin Oxide covered Quartz Electrodes for Photo-Electrochemical Water Splitting

    International Nuclear Information System (INIS)

    Hernández, Simelys; Tortello, Mauro; Sacco, Adriano; Quaglio, Marzia; Meyer, Toby; Bianco, Stefano; Saracco, Guido; Pirri, C. Fabrizio; Tresso, Elena

    2014-01-01

    Graphical abstract: - Highlights: • A new transparent, conductive and porous electrode was developed. • It has a high effective surface area available for catalyst molecules attachment. • It is an ideal support for testing new anodic and cathodic photoactive materials. • The proof-of-concept was achieved in an appositely designed water photo-electrolyzer. • The EIS technique was used as a very powerful tool to characterize the new designed electrode. - Abstract: A new-designed transparent, conductive and porous electrode was developed for application in a compact laboratory-scale proton exchange membrane (PEM) photo-electrolyzer. The electrode is made of a thin transparent quartz sheet covered with fluorine-doped tin oxide (FTO), in which an array of holes is laser-drilled to allow water and gas permeation. The electrical, morphological, optical and electrochemical characterization of the drilled electrodes is presented in comparison with a non-drilled one. The drilled electrode exhibits, in the visible region, a good transmittance (average value of 62%), a noticeable reflectance due to the light scattering effect of the hole-drilled internal region, and a higher effective surface area than the non-drilled electrode. The proof-of-concept of the applicability of the drilled electrode was achieved by using it as a support for a traditional photocatalyst (i.e. commercial TiO 2 nanoparticles). The latter, coupled with a polymeric electrolyte membrane (i.e.Nafion 117) and a Pt counter electrode, forms a transparent membrane electrode assembly (MEA), with a good conductivity, wettability and porosity. Electrochemical impedance spectroscopy (EIS) was used as a very powerful tool to gain information on the real active surface of the new drilled electrode and the main electrochemical parameters driving the charge transfer reactions on it. This new electrode architecture is demonstrated to be an ideal support for testing new anodic and cathodic photoactive

  11. A novel and selective fluoride opening of aziridines by XtalFluor-E. synthesis of fluorinated diamino acid derivatives.

    Science.gov (United States)

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

    2015-03-06

    The selective introduction of fluorine onto the skeleton of an aminocyclopentane or cyclohexane carboxylate has been developed through a novel and efficient fluoride opening of an activated aziridine ring with XtalFluor-E. The reaction proceeded through a stereoselective aziridination of the olefinic bond of a bicyclic lactam and regioselective aziridine ring opening with difluorosulfiliminium tetrafluoroborate with the neighboring group assistance of the sulfonamide moiety to yield fluorinated diamino acid derivatives. The method based on the selective aziridine opening by fluoride has been generalized to afford access to mono- or bicyclic fluorinated substances.

  12. Impact of carbon-fluorine doped titanium dioxide in the performance of an electrochemical sensing of dopamine and rosebengal sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Abinaya C

    2015-01-01

    Full Text Available The role of Fluorine and Carbon as dopants in the TiO2 based electrochemical sensor and DSSC were presented in this work. A series of Carbon nano-cones and disc doped TiO2 (TC, Fluorine doped TiO2 (FT and C & F co-doped TiO2 (CFT powdered samples were prepared via solid state synthesis. The CFT film showed excellent electrochemical sensitivity to the oxidation of dopamine in aqueous solution and could be employed as a dopamine sensor. The proposed sensor exhibited good linear response in the range of 10-820 μM with a detection limit of 3.6 μM under optimum conditions. The photovoltaic performances of Rose Bengal sensitized solar cells were assessed through I-V measurements. The CFT based DSSC shows a short-circuit current density and a power conversion efficiency (η of 0.908 mA/cm2 and 0.163% respectively, which is 35% and 38% greater than the performance of other PT based cells. The characterization studies such as UV-Visible spectroscopy, Photoluminescence, TEM and EPR spectroscopy were utilized for further investigation, which helps us to understand how fluorine and carbon play a part in dopamine sensing and solar energy conversion.

  13. Fluorination of Naturally Occurring N6-Benzyladenosine Remarkably Increased Its Antiviral Activity and Selectivity

    Directory of Open Access Journals (Sweden)

    Vladimir E. Oslovsky

    2017-07-01

    Full Text Available Recently, we demonstrated that the natural cytokinin nucleosides N6-isopentenyladenosine (iPR and N6-benzyladenosine (BAPR exert a potent and selective antiviral effect on the replication of human enterovirus 71. In order to further characterize the antiviral profile of this class of compounds, we generated a series of fluorinated derivatives of BAPR and evaluated their activity on the replication of human enterovirus 71 in a cytopathic effect (CPE reduction assay. The monofluorination of the BAPR-phenyl group changed the selectivity index (SI slightly because of the concomitant high cell toxicity. Interestingly, the incorporation of a second fluorine atom resulted in a dramatic improvement of selectivity. Moreover, N6-trifluoromethylbenzyladenosine derivatives (9–11 exhibited also a very interesting profile, with low cytotoxicity observed. In particular, the analogue N6-(3-trifluoromethylbenzyl-adenosine (10 with a four-fold gain in potency as compared to BAPR and the best SI in the class represents a promising candidate for further development.

  14. Selective C-H Halogenation with a Highly Fluorinated Manganese Porphyrin.

    Science.gov (United States)

    Li, Gang; Dilger, Andrew K; Cheng, Peter T; Ewing, William R; Groves, John T

    2018-01-26

    The selective C-H functionalization of aliphatic molecules remains a challenge in organic synthesis. While radical chain halogenation reactions provide efficient access to many halogenated molecules, the use of typical protocols for the selective halogenation of electron-deficient and strained aliphatic molecules is rare. Herein, we report selective C-H chlorination and fluorination reactions promoted by an electron-deficient manganese pentafluorophenyl porphyrin catalyst, Mn(TPFPP)Cl. This catalyst displays superior properties for the aliphatic halogenation of recalcitrant, electron-deficient, and strained substrates with unique regio- and stereoselectivity. UV/Vis analysis during the course of the reaction indicated that an oxo-Mn V species is responsible for hydrogen-atom abstraction. The observed stereoselectivity results from steric interactions between the bulky porphyrin ligand and the intermediate substrate radical in the halogen rebound step. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Fluorinated Nucleotide Modifications Modulate Allele Selectivity of SNP-Targeting Antisense Oligonucleotides

    Directory of Open Access Journals (Sweden)

    Michael E. Østergaard

    2017-06-01

    Full Text Available Antisense oligonucleotides (ASOs have the potential to discriminate between subtle RNA mismatches such as SNPs. Certain mismatches, however, allow ASOs to bind at physiological conditions and result in RNA cleavage mediated by RNase H. We showed that replacing DNA nucleotides in the gap region of an ASO with other chemical modification can improve allele selectivity. Herein, we systematically substitute every position in the gap region of an ASO targeting huntingtin gene (HTT with fluorinated nucleotides. Potency is determined in cell culture against mutant HTT (mtHTT and wild-type HTT (wtHTT mRNA and RNase H cleavage intensities, and patterns are investigated. This study profiled five different fluorinated nucleotides and showed them to have predictable, site-specific effects on RNase H cleavage, and the cleavage patterns were rationalized from a published X-ray structure of human RNase H1. The results herein can be used as a guide for future projects where ASO discrimination of SNPs is important.

  16. Selective vibrational excitation of the ethylene--fluorine reaction in a nitrogen matrix. II

    International Nuclear Information System (INIS)

    Frei, H.

    1983-01-01

    The product branching between 1,2-difluoroethane and vinyl fluoride (plus HF) of the selective vibrationally stimulated reaction of molecular fluorine with C 2 H 4 has been studied in a nitrogen matrix at 12 K and found to be the same for five different vibrational transitions of C 2 H 4 between 1896 and 4209 cm -1 . The HF/DF branching ratio of the reaction of F 2 with CH 2 CD 2 , trans-CHDCHD, and cis-CHDCHD was determined to be 1.1, independent of precursor C 2 H 2 D 2 isomer and particular mode which excited the reaction. These results, as well as the analysis of the mixtures of partially deuterated vinyl fluoride molecules produced by each C 2 H 2 D 2 isomer indicate that the product branching occurs by αβ elimination of HF(DF) from a vibrationally excited, electronic ground state 1,2-difluoroethane intermediate. Selective vibrational excitation of fluorine reactions in isotopically mixed matrices t-CHDCHD/C 2 H 4 /F 2 /N 2 and CH 2 CD 2 /C 2 H 4 /F 2 /N 2 , and in matrices C 2 H 2 /C 2 H 4 /F 2 /N 2 revealed a high degree of isotopic and molecular selectivity. The extent to which intermolecular energy transfer occurred is qualitatively explained in terms of dipole coupled vibrational energy transfer. A study of the loss of absorbance of the C 2 H 4 x F 2 pairs in case of ν 9 as a function of both the laser irradiation frequency within the absorption profile, and the ethylene concentration showed that the C 2 H 4 x F 2 absorption is inhomogeneously broadened. Substantial depletion of reactive pairs which did not absorb laser light is interpreted in terms of Forster transfer

  17. GLUT1-mediated selective tumor targeting with fluorine containing platinum(II) glycoconjugates.

    Science.gov (United States)

    Liu, Ran; Fu, Zheng; Zhao, Meng; Gao, Xiangqian; Li, Hong; Mi, Qian; Liu, Pengxing; Yang, Jinna; Yao, Zhi; Gao, Qingzhi

    2017-06-13

    Increased glycolysis and overexpression of glucose transporters (GLUTs) are physiological characteristics of human malignancies. Based on the so-called Warburg effect, 18flurodeoxyglucose-positron emission tomography (FDG-PET) has successfully developed as clinical modality for the diagnosis and staging of many cancers. To leverage this glucose transporter mediated metabolic disparity between normal and malignant cells, in the current report, we focus on the fluorine substituted series of glucose, mannose and galactose-conjugated (trans-R,R-cyclohexane-1,2-diamine)-2-flouromalonato-platinum(II) complexes for a comprehensive evaluation on their selective tumor targeting. Besides highly improved water solubility, these sugar-conjugates presented improved cytotoxicity than oxaliplatin in glucose tranporters (GLUTs) overexpressing cancer cell lines and exhibited no cross-resistance to cisplatin. For the highly water soluble glucose-conjugated complex (5a), two novel in vivo assessments were conducted and the results revealed that 5a was more efficacious at a lower equitoxic dose (70% MTD) than oxaliplatin (100% MTD) in HT29 xenograft model, and it was significantly more potent than oxaliplatin in leukemia-bearing DBA/2 mice as well even at equimolar dose levels (18% vs 90% MTD). GLUT inhibitor mediated cell viability analysis, GLUT1 knockdown cell line-based cytotoxicity evaluation, and platinum accumulation study demonstrated that the cellular uptake of the sugar-conjugates was regulated by GLUT1. The higher intrinsic DNA reactivity of the sugar-conjugates was confirmed by kinetic study of platinum(II)-guanosine adduct formation. The mechanistic origin of the antitumor effect of the fluorine complexes was found to be forming the bifunctional Pt-guanine-guanine (Pt-GG) intrastrand cross-links with DNA. The results provide a rationale for Warburg effect targeted anticancer drug design.

  18. Structural and biochemical studies of a fluoroacetyl-CoA-specific thioesterase reveal a molecular basis for fluorine selectivity.

    Science.gov (United States)

    Weeks, Amy M; Coyle, Scott M; Jinek, Martin; Doudna, Jennifer A; Chang, Michelle C Y

    2010-11-02

    We have initiated a broad-based program aimed at understanding the molecular basis of fluorine specificity in enzymatic systems, and in this context, we report crystallographic and biochemical studies on a fluoroacetyl-coenzyme A (CoA) specific thioesterase (FlK) from Streptomyces cattleya. Our data establish that FlK is competent to protect its host from fluoroacetate toxicity in vivo and demonstrate a 10(6)-fold discrimination between fluoroacetyl-CoA (k(cat)/K(M) = 5 × 10⁷ M⁻¹ s⁻¹) and acetyl-CoA (k(cat)/K(M) = 30 M⁻¹ s⁻¹) based on a single fluorine substitution that originates from differences in both substrate reactivity and binding. We show that Thr 42, Glu 50, and His 76 are key catalytic residues and identify several factors that influence substrate selectivity. We propose that FlK minimizes interaction with the thioester carbonyl, leading to selection against acetyl-CoA binding that can be recovered in part by new C═O interactions in the T42S and T42C mutants. We hypothesize that the loss of these interactions is compensated by the entropic driving force for fluorinated substrate binding in a hydrophobic binding pocket created by a lid structure, containing Val 23, Leu 26, Phe 33, and Phe 36, that is not found in other structurally characterized members of this superfamily. We further suggest that water plays a critical role in fluorine specificity based on biochemical and structural studies focused on the unique Phe 36 "gate" residue, which functions to exclude water from the active site. Taken together, the findings from these studies offer molecular insights into organofluorine recognition and design of fluorine-specific enzymes.

  19. Continuous gas/liquid–liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination

    Directory of Open Access Journals (Sweden)

    Jessica R. Breen

    2011-08-01

    Full Text Available 4-Fluoropyrazole systems may be prepared by a single, sequential telescoped two-step continuous gas/liquid–liquid/liquid flow process from diketone, fluorine gas and hydrazine starting materials.

  20. Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation

    DEFF Research Database (Denmark)

    Viswanathan, Venkatasubramanian; Hansen, Heine Anton; Nørskov, Jens K.

    2015-01-01

    evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH* can be used to determine selectivity trends between the 2e(-) water oxidation to H2O2 and the 4e(-) oxidation to O2. We show that materials which bind oxygen intermediates...... sufficiently weakly, such as SnO2, can activate hydrogen peroxide evolution. We present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H2O2 evolution selectively....

  1. Electrochemical oxidation of selective estrogen receptor modulator raloxifene

    International Nuclear Information System (INIS)

    Li, Xi-Qian; He, Jian-Bo; Liu, Lu; Cui, Ting

    2013-01-01

    Highlights: ► Application and analysis of in situ thin-layer spectroelectrochemistry. ► Cyclic voltabsorptometry used for a drug study. ► Highly pH-dependent oxidative metabolism of raloxifene. ► A complex parallel-consecutive mechanism proposed for oxidation of raloxifene. -- Abstract: Raloxifene is a selective estrogen receptor modulator that may produce toxic oxidative species in metabolism. The oxidation mechanism of raloxifene with different pH values was studied by cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), in situ UV–vis spectral analysis and cyclic voltabsorptometry based on a long optical-path thin-layer electrochemical cell. Time-derivative cyclic voltabsorptograms were obtained for comparative discussion with the corresponding cyclic voltammograms. Raloxifene was initially oxidized to reactive phenoxyl radicals, followed by a series of transformation steps leading to different final products in different pH media. A parallel-consecutive reaction mechanism was proposed for the pH-dependent formation of 7-hydroxyraloxifene, raloxifene 6,7-o-quinone and two raloxifene dimers, each pathway following a complex electrochemical-chemical mechanism. Both raloxifene diquinone methide and its N-oxides were not detected by in situ UV–vis spectroscopy and XPS analysis. This work provides an electrochemical viewpoint and comparable information for better understanding of the oxidative metabolism and chemical toxicology of raloxifene under physiological conditions in vivo or in vitro

  2. GLUT1-mediated selective tumor targeting with fluorine containing platinum(II) glycoconjugates

    OpenAIRE

    Liu, Ran; Fu, Zheng; Zhao, Meng; Gao, Xiangqian; Li, Hong; Mi, Qian; Liu, Pengxing; Yang, Jinna; Yao, Zhi; Gao, Qingzhi

    2017-01-01

    Increased glycolysis and overexpression of glucose transporters (GLUTs) are physiological characteristics of human malignancies. Based on the so-called Warburg effect, 18flurodeoxyglucose-positron emission tomography (FDG-PET) has successfully developed as clinical modality for the diagnosis and staging of many cancers. To leverage this glucose transporter mediated metabolic disparity between normal and malignant cells, in the current report, we focus on the fluorine substituted series of glu...

  3. Fluorine-Directed Glycosylation Enables the Stereocontrolled Synthesis of Selective SGLT2 Inhibitors for Type II Diabetes.

    Science.gov (United States)

    Sadurní, Anna; Kehr, Gerald; Ahlqvist, Marie; Wernevik, Johan; Sjögren, Helena Peilot; Kankkonen, Cecilia; Knerr, Laurent; Gilmour, Ryan

    2018-02-26

    Inhibition of the sodium-glucose co-transporters (SGLT1 and SGLT2) is a validated strategy to address the increasing prevalence of type II diabetes mellitus. However, achieving selective inhibition of human SGLT1 or SGLT2 remains challenging. Orally available small molecule drugs based on the d-glucose core of the natural product Gliflozin have proven to be clinically effective in this regard, effectively impeding glucose reabsorption. Herein, we disclose the influence of molecular editing with fluorine at the C2 position of the pyranose ring of Phlorizin analogues Remogliflozin Etabonate and Dapagliflozin (Farxiga ® ) to concurrently direct β-selective glycosylation, as is required for biological efficacy, and enhance aspects of the physicochemical profile. Given the abundance of glycosylated pharmaceuticals in diabetes therapy that contain a β-configured d-glucose nucleus, it is envisaged that this strategy may prove to be expansive. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Semi-fluorinated sulfonated polyimide membranes with enhanced proton selectivity and stability for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Li, Jinchao; Liu, Suqin; He, Zhen; Zhou, Zhi

    2016-01-01

    A series of semi-fluorinated sulfonated polyimides (6F-SPIs) are designed and synthesized via a one-step high-temperature polycondensation reaction. The sulfonation degrees of 6F-SPIs are controlled through changing the ratio of sulfonated diamine to non-sulfonated diamine in the casting solution. The physico-chemical properties and single cell performance of 6F-SPI membranes are thoroughly evaluated and compared to a non-fluorinated SPI membrane (6H-SPI-50) and a Nafion 115 membrane. The results show that the designed 6F-SPI membrane with a 50% sulfonation degree (6F-SPI-50) possesses the highest proton selectivity (1.613 × 10 5 S min cm −3 ) among all tested membranes. Besides, the 6F-SPI-50 membrane exhibits a promising performance for vanadium redox flow batteries (VRFBs), showing higher coulombic efficiencies (96.90–99.20%) and energy efficiencies (88.25–64.80%) than the Nafion 115 membrane (with coulombic efficiencies of 90.60–96.70% and energy efficiencies of 81.04–60.10%) at the current densities ranging from 20 to 100 mA cm −2 . Moreover, the 6F-SPI-50 membrane shows excellent chemical stability in the VRFB system. This work paves the way for the development of a new class of 6F-SPI membranes for the VRFB application.

  5. Method for selectively removing fluorine and fluorine-containing contaminants from gaseous UF/sub 6/. [ClF/sub 3/

    Science.gov (United States)

    Jones, R.L.; Otey, M.G.; Perkins, R.W.

    1980-11-24

    This invention is a method for effecting preferential removal and immobilization of certain gaseous contaminants from gaseous UF/sub 6/. The contaminants include fluorine and fluorides which are more reactive with CaCO/sub 3/ than is UF/sub 6/. The method comprises contacting the contaminant-carrying UF/sub 6/ with particulate CaCO/sub 3/ at a temperature effecting reaction of the contaminant and the CaCO/sub 3/.

  6. Selective Leaching of Gray Cast Iron: Electrochemical Aspects

    International Nuclear Information System (INIS)

    Na, Kyung Hwan; Yun, Eun Sub; Park, Young Sheop

    2010-01-01

    Currently, to keep step with increases in energy consumption, much attention has been paid to the construction of new nuclear power plants (NPPs) and to the continued operation of NPPs. For continued operation, the selective leaching of materials should be evaluated by visual inspections and hardness measurements as a part of One-Time Inspection Program according to the requirements of the guidelines for continued operation of pressured water reactors (PWRs) in Korea and license renewals in the United States, entitled the 'Generic Aging Lessons Learned (GALL) report.' However, the acceptance criteria for hardness have yet to be provided. Recently, USNRC released a new draft of the GALL report for comment and plans to publish its formal version by the end of 2010. In the new draft, the quantitative acceptance criteria for hardness are given at last: no more than a 20 percent decrease in hardness for gray cast iron and brass containing more than 15 percent zinc. Selective leaching is the preferential removal of one of the alloying elements from a solid alloy by corrosion processes, leaving behind a weakened spongy or porous residual structure. The materials susceptible to selective leaching include gray cast iron and brass, which are mainly used as pump casings and valve bodies in the fire protection systems of NPPs. Since selective leaching proceeds slowly during a long period of time and causes a decrease in strength without changing the overall dimensions of original material, it is difficult to identify. In the present work, the selective leaching of gray cast iron is investigated in terms of its electrochemical aspects as part of an ongoing research project to study the changes in metal properties by selective leaching

  7. Selective Electrochemical Detection of Epinephrine Using Gold Nanoporous Film

    Directory of Open Access Journals (Sweden)

    Dina M. Fouad

    2016-01-01

    Full Text Available Epinephrine (EP is one of the important catecholamine neurotransmitters that play an important role in the mammalian central nervous system. Therefore, it is necessary to determine the change of its concentrations. Nanoporous materials have wide applications that include catalysis, energy storages, environmental pollution control, wastewater treatment, and sensing applications. These unique properties could be attributable to their high surface area, a large pore volume, and uniform pore sizes. A gold nanoporous layer modified gold electrode was prepared and applied for the selective determination of epinephrine neurotransmitter at low concentration in the presence of several other substances including ascorbic acid (AA and uric acid (UA. The constructed electrode was characterized using scanning electron microscopy and cyclic voltammetry. The resulting electrode showed a selective detection of epinephrine with the interferences of dopamine and uric acid over a wide linear range (from 50 μM to 1 mM. The coverage of gold nanoporous on the surface of gold electrode represents a promising electrochemical sensor with high selectivity and sensitivity.

  8. 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.

  9. Selective Adsorption on Fluorinated Plastic Enables the Optical Detection of Molecular Pollutants in Water

    Science.gov (United States)

    Lanfranco, R.; Giavazzi, F.; Salina, M.; Tagliabue, G.; Di Nicolò, E.; Bellini, T.; Buscaglia, M.

    2016-05-01

    Amorphous fluorinated plastic can be produced with a refractive index similar to that of water, a condition that makes it essentially invisible when immersed in aqueous solutions. Because of this property, even a small amount of adsorbed molecules on the plastic-water interface provides a detectable optical signal. We investigate two distinct substrates made of this material, characterized by different interface areas: a prism and a microporous membrane. We demonstrate that both substrates enable the label-free detection of molecular compounds in water even without any surface functionalization. The adsorption of molecules on the planar surface of the prism provides an increase of optical reflectivity, whereas the adsorption on the internal surface of the microporous membrane yields an increase of scattered light. Despite the different mechanisms, we find a similar optical response upon adsorption. We confirm this result by a theoretical model accounting for both reflection and scattering. We investigate the spontaneous adsorption process for different kinds of molecules: surfactants with different charges, a protein (lysozyme), and a constituent of gasoline (hexane). The measured equilibrium and kinetic constants for adsorption differ by orders of magnitudes among the different classes of molecules. By suitable analytical models, accounting for the effects of mass limitation and transport, we find a simple and general scaling of the adsorption parameters with the molecular size.

  10. Effect of fluorination treatment on electrochemical properties of M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} hydrogen storage alloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hongxia, E-mail: hhxhunan@yahoo.com.cn [College of Chemistry and Bioengineering, Guilin University of Technology, Guilin (China); Huang, Kelong [College of Chemistry and Chemical Engineering, Central South University (China)

    2012-05-15

    The influence of surface treatment by solutions of NH{sub 4}F, LiF and LiF containing KBH{sub 4} on the structure and electrochemical properties of the M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} hydrogen storage alloy (in which M1 denotes mischmetal) is investigated. The fluorination treatment improves the electrochemical performances of the M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} alloy. The maximum discharge capacity (C{sub max}) increases from 314.8 to 325.7 (NH{sub 4}F), 326.5 (LiF) and 316.4 mAh g{sup -1} (LiF+KBH{sub 4}). After 60 cycles, the capacity retention rate increases from 83.5 to 84.8% (NH{sub 4}F), 89.5% (LiF) and 93.9% (LiF+KBH{sub 4}). The results of the linear polarization and anodic polarization reveal that the exchange current density (I{sub 0}) and the limiting current density (I{sub L}) increase after fluorination treatment, indicating an improvement of the kinetics of the hydrogen absorption/desorption. (author)

  11. High Performance Enhancement-Mode AlGaN/GaN MIS-HEMT with Selective Fluorine Treatment

    Directory of Open Access Journals (Sweden)

    Chao Yang

    2015-01-01

    Full Text Available A novel enhancement-mode (E-mode Metal-Insulator-Semiconductor- (MIS- HEMT with selective fluorine ion (F− treatment is proposed and its mechanism is investigated. The HEMT features the Selective F− treatment both in the AlGaN channel region and in the thick passivation layer between the gate and drain (SFCP-MIS-HEMT. First, the F− in the passivation layer not only extends the depletion region and thus enhances the average electric field (E-field between the gate and drain by the assisted depletion effect but also reduces the E-field peak at the gate end, leading to a higher breakdown voltage (BV. Second, in the AlGaN channel region, the F− region realizes the E-mode and the region without F− maintains a high drain current (ID. Third, MIS structure suppresses the gate leakage current, increasing the gate swing voltage and the BV. Compared with a MIS-HEMT with F− treatment in whole channel (FC-MIS-HEMT, SFCP-MIS-HEMT increases the BV by 46% and the saturation drain current (ID,sat by 28%.

  12. Selective electrochemical gold deposition onto p-Si (1 0 0) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Santinacci, L; Etcheberry, A [Institut Lavoisier de Versailles (UMR CNRS 8180), University of Versailles-Saint-Quentin, 45 avenue des Etats-Unis, F-78035 Versailles cedex (France); Djenizian, T [Laboratoire Chimie Provence (UMR CNRS 6264), University of Aix-Marseille I-II-III, Centre Saint-Jerome, F-13397 Marseille Cedex 20 (France); Schwaller, P [Laboratory for Mechanics of Materials and Nanostructures, Swiss Federal Laboratory for Materials Testing and Research, Feuerwerkstr. 39, CH-3602 Thun (Switzerland); Suter, T [Laboratory for Corrosion and Materials Integrity, Swiss Federal Laboratory for Materials Testing and Research, Ueberlandstr. 129, CH-8600 Duebendorf (Switzerland); Schmuki, P [Department of Materials Science, LKO-WW4, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 7, D-91058 Erlangen (Germany)], E-mail: lionel.santinacci@uvsq.fr

    2008-09-07

    In this paper, we report selective electrochemical gold deposition onto p-type Si (1 0 0) into nanoscratches produced through a thin oxide layer using an atomic force microscope. A detailed description of the substrate engraving process is presented. The influence of the main scratching parameters such as the normal applied force, the number of scans and the scanning velocity are investigated as well as the mechanical properties of the substrate. Gold deposition is carried out in a KAu(CN){sub 2} + KCN solution by applying cathodic voltages for various durations. The gold deposition process is investigated by cyclic voltammetry. Reactivity enhancement at the scratched locations was studied by comparing the electrochemical behaviour of intact and engraved surfaces using a micro-electrochemical setup. Selective electrochemical gold deposition is achieved: metallic patterns with a sub-500 nm lateral resolution are obtained demonstrating, therefore, the bearing potential of this patterning technique.

  13. 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)

  14. ELECTROCHEMICAL FINGERPRINT STUDIES OF SELECTED MEDICINAL PLANTS RICH IN FLAVONOIDS.

    Science.gov (United States)

    Konieczyński, Paweł

    2015-01-01

    The combination of a size-exclusion column (SEC) with electrochemical (voltammetric) detection at a boron-doped diamond electrode (BDDE) was applied for studying the correlations between electroactive Cu and Fe species with phenolic groups of flavonoids. For comparison with electrochemical results, SEC-HPLC-DAD detection was used. The studied plant material comprised of: Betula verrucosa Ehrh., Equisetun arvense L., Polygonum aviculare L., Viola tricolor L., Crataegus oxyacantha L., Sambucus nigra L. and Helichrysum arenarium (L.) Moench. Based upon the results, high negative correlation was found for the chromatographic peak currents at 45 min with the sum of Cu and Fe for the aqueous extracts of Sambucus, Crataegus and Betula species, and for the peak currents at 65 min of the aqueous extracts of Sambucus, Crataegus, Helichrysum and Betula botanical species. This behavior confirms that it is mainly the flavonoids with easily oxidizable phenolic groups which are strongly influenced by the presence of Cu and Fe. Moreover, the electrochemical profiles obtained thanks to the use of HPLC hyphenated with voltammetric detection can be potentially applied for fingerprint studies of the plant materials used in medicine.

  15. Active control of methanol carbonylation selectivity over Au/carbon anode by electrochemical potential.

    Science.gov (United States)

    Funakawa, Akiyasu; Yamanaka, Ichiro; Otsuka, Kiyoshi

    2005-05-12

    Electrochemical oxidative carbonylation of methanol was studied over Au supported carbon anode in CO. The major carbonylation products were dimethyl oxalate (DMO) and dimethyl carbonate (DMC). The minor oxidation products were dimethoxy methane (DMM) and methyl formate (MF) from methanol and CO(2). Influences of various reaction conditions were studied on carbonylation activities and selectivities. The selectivities to DMO and DMC can be controlled by the electrochemical potential. Electrocatalysis of Au/carbon anode was studied by cyclic voltammetry (CV), stoichiometric reactions among Au(3+), methanol, and CO, and UV-vis spectra. The Au/carbon anode was characterized by XRD, SEM, and BE images before and after the carbonylation. These experimental facts strongly suggest that transition of oxidation states of Au affects changing of the carbonylation selectivities to DMO and DMC. Au(0) is the active species for the selective DMO formation by direct electrochemical carbonylation at low potentials (selective DMC formation by indirect electrochemical carbonylation through Au(3+)/Au(+) redox at high potentials (>+1.3 V).

  16. Polypyrrole Composite Film for Highly Sensitive and Selective Electrochemical Determination Sensors

    International Nuclear Information System (INIS)

    Zheng, Xiangli; Tian, Dong; Duan, Shuo; Wei, Maochao; Liu, Shan; Zhou, Changli; Li, Qing; Wu, Gang

    2014-01-01

    In this paper, polypyrrole (PPy) and benz[a]anthracene-7,12-dione (BaD) were electro-polymerized onto a pyrolytic graphite electrode (PGE), constructing a novel BaD/PPy/PGE platform for electrochemical sensoring. The morphology and electrochemical properties of the fabricated BaD/PPy/PGE were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Furthermore, the electrochemical behavior of benzo[k]fluoranthene (BkF) at the BaD/PPy/PGE was investigated. Due to the specific interactions between BkF and BaD, a wide linear range of BkF detection from 1.0 × 10 −12 to 1.0 × 10 −9 M with good linearity (R 2 = 0.9962) and a low detection limit (1.0 × 10 −13 M, S/N = 3) were demonstrated. Importantly, other similar aromatics which had one ring or more than two rings, such as benzo[a]anthracene, benzo[a]pyrene, pyrene, benzo[ghi]peryle, anthracene, phenanthrene, naphthalene and parachlorophenol, showed insignificant interference on BkF detection. Consequently, this novel BaD/PPy/PGE with excellent stability and selectivity holds promise as an effective BkF electrochemical sensor in aqueous solution. As an example for its practical application, the newly developed sensor was applied to quantitative determination of BkF in waste water samples obtained from a coking plant with satisfactory sensitivity, selectivity, and reversibility

  17. Selective electrochemical extraction of REEs from NdFeB magnet waste at room temperature

    NARCIS (Netherlands)

    Venkatesan, P.; Vander Hoogerstraete, Tom; Hennebel, Tom; Binnemans, Koen; Sietsma, J.; Yang, Y.

    2018-01-01

    NdFeB magnet waste is one of the important secondary resources from which rare-earth elements (REEs) can be recovered. Herein we present an electrochemical route to selectively extract REEs from the magnet waste at room temperature. First, the magnet waste was partially leached with HCl. The

  18. The selectivity of zirconium phosphate for caesium in electrochemical ion exchange

    International Nuclear Information System (INIS)

    Lain, M.J.

    1988-11-01

    The properties of amorphous zirconium phosphate are investigated as an inorganic ion exchanger for use in liquid waste treatment by electrochemical ion exchange. Experiments to determine and increase the selectivity for caesium exchange over sodium are discussed, including various pulsed waveforms and studies with rotating membranes. Automation of a sampling system with pH and atomic absorption measurements is described. (author)

  19. Selective electrochemical determination of homocysteine in the presence of cysteine and glutathione

    International Nuclear Information System (INIS)

    Salehzadeh, Hamid; Mokhtari, Banafsheh; Nematollahi, Davood

    2014-01-01

    Graphical abstract: 3,5-Di-tert-buthylcatechol was used for the selective electrochemical determination of homocysteine in the presence of cysteine and glutathione at the glassy carbon and carbon nanotube modified glassy carbon electrode. - Highlights: • Selective electrochemical determination of homocysteine. • Catalytic electron transfer of 3,5-di-tert-buthylcatechol in the presence of homocysteine. • Michael type addition reaction of electrochemically generated 3,5-di-tert-buthyl-o-benzoquinone with glutathione. - Abstract: The electrochemical oxidation of 3,5-di-tert-buthylcatechol in the presence of homocysteine was used for the selective electrochemical determination of homocysteine in the presence of cysteine and glutathione at a glassy carbon and a glassy carbon electrode modified with carbon nanotube. The results revealed that the electrochemically generated 3,5-di-tert-butylcyclohexa-3,5-diene-1,2-dione exhibits high catalytic activity toward homocysteine oxidation at reduced over-potential and low catalytic activity for oxidation of cysteine. The catalytic activity 3,5-di-tert-butylcyclohexa-3,5-diene-1,2-dione toward cysteine was suppressed in the presence of 4-N,N-dimethylaminocinnamaldehyde. Contrary to homocysteine and cysteine, the reaction of glutathione with 3,5-di-tert-butylcyclohexa-3,5-diene-1,2-dione is a substituation reaction. This method exhibits three dynamic linear ranges of 2.5 to 10 μmol L −1 , 10 to 100 μmol L −1 and 100 to 1000 μmol L −1 , and a lower detection limit (3σ) of 0.89 ± 3.53% μmol L −1 for homocysteine

  20. Simplifying the complex 1H NMR spectra of fluorine-substituted benzamides by spin system filtering and spin-state selection: multiple-quantum-single-quantum correlation.

    Science.gov (United States)

    Baishya, Bikash; Reddy, G N Manjunatha; Prabhu, Uday Ramesh; Row, T N Guru; Suryaprakash, N

    2008-10-23

    The proton NMR spectra of fluorine-substituted benzamides are very complex (Figure 1) due to severe overlap of (1)H resonances from the two aromatic rings, in addition to several short and long-range scalar couplings experienced by each proton. With no detectable scalar couplings between the inter-ring spins, the (1)H NMR spectra can be construed as an overlap of spectra from two independent phenyl rings. In the present study we demonstrate that it is possible to separate the individual spectrum for each aromatic ring by spin system filtering employing the multiple-quantum-single-quantum correlation methodology. Furthermore, the two spin states of fluorine are utilized to simplify the spectrum corresponding to each phenyl ring by the spin-state selection. The demonstrated technique reduces spectral complexity by a factor of 4, in addition to permitting the determination of long-range couplings of less than 0.2 Hz and the relative signs of heteronuclear couplings. The technique also aids the judicious choice of the spin-selective double-quantum-single-quantum J-resolved experiment to determine the long-range homonuclear couplings of smaller magnitudes.

  1. 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.

  2. 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.

  3. Influence of particle size and fluorination ratio of CFx precursor compounds on the electrochemical performance of C–FeF2 nanocomposites for reversible lithium storage

    Directory of Open Access Journals (Sweden)

    Ben Breitung

    2013-11-01

    Full Text Available Systematical studies of the electrochemical performance of CFx-derived carbon–FeF2 nanocomposites for reversible lithium storage are presented. The conversion cathode materials were synthesized by a simple one-pot synthesis, which enables a reactive intercalation of nanoscale Fe particles in a CFx matrix, and the reaction of these components to an electrically conductive C–FeF2 compound. The pretreatment and the structure of the utilized CFx precursors play a crucial role in the synthesis and influence the electrochemical behavior of the conversion cathode material. The particle size of the CFx precursor particles was varied by ball milling as well as by choosing different C/F ratios. The investigations led to optimized C–FeF2 conversion cathode materials that showed specific capacities of 436 mAh/g at 40 °C after 25 cycles. The composites were characterized by Raman spectroscopy, X-Ray diffraction measurements, electron energy loss spectroscopy and TEM measurements. The electrochemical performances of the materials were tested by galvanostatic measurements.

  4. Kinetic studies of electrochemical generation of Ag(II) ion and catalytic oxidation of selected organics

    International Nuclear Information System (INIS)

    Zawodzinski, C.; Smith, W.H.; Martinez, K.R.

    1993-01-01

    The goal of this research is to develop a method to treat mixed hazardous wastes containing selected organic compounds and heavy metals, including actinide elements. One approach is to destroy the organic via electrochemical oxidation to carbon dioxide, then recover the metal contaminants through normally accepted procedures such as ion exchange, precipitation, etc. The authors have chosen to study the electrochemical oxidation of a simple alcohol, iso-propanol. Much of the recent work reported involved the use of an electron transfer mediator, usually the silver(I)/(II) redox couple. This involved direct electrochemical generation of the mediator at the anode of a divided cell followed by homogeneous reaction of the mediator with the organic compound. In this study the authors have sought to compare the mediated reaction with direct electrochemical oxidation of the organic. In addition to silver(I)/(II) they also looked at the cobalt(II)/(III) redox coupled. In the higher oxidation state both of these metal ions readily hydrolyze in aqueous solution to ultimately form insoluble oxide. The study concluded that in a 6M nitric acid solution at room temperature iso-propanol can be oxidized to carbon dioxide and acetic acid. Acetic acid is a stable intermediate and resists further oxidation. The presence of Co(III) enhances the rate or efficiency of the reaction

  5. Highly Selective Polypyrrole MIP-Based Gravimetric and Electrochemical Sensors for Picomolar Detection of Glyphosate

    Directory of Open Access Journals (Sweden)

    Zouhour Mazouz

    2017-11-01

    Full Text Available There is a global debate and concern about the use of glyphosate (Gly as an herbicide. New toxicological studies will determine its use in the future under new strict conditions or its replacement by alternative synthetic or natural herbicides. In this context, we designed biomimetic polymer sensing layers for the selective molecular recognition of Gly. Towards this end, complementary surface acoustic wave (SAW and electrochemical sensors were functionalized with polypyrrole (PPy-imprinted polymer for the selective detection of Gly. Their corresponding limits of detection were on the order of 1 pM, which are among the lowest values ever reported in literature. The relevant dissociation constants between PPy and Gly were estimated at [Kd1 = (0.7 ± 0.3 pM and Kd2 = (1.6 ± 1.4 µM] and [Kd1 = (2.4 ± 0.9 pM and Kd2 = (0.3 ± 0.1 µM] for electrochemical and gravimetric measurements, respectively. Quantum chemical calculations permitted to estimate the interaction energy between Gly and PPy film: ΔE = −145 kJ/mol. Selectivity and competitivity tests were investigated with the most common pesticides. This work conclusively shows that gravimetric and electrochemical results indicate that both MIP-based sensors are perfectly able to detect and distinguish glyphosate without any ambiguity.

  6. Fluorination of polymers

    International Nuclear Information System (INIS)

    Du Toit, F.J.

    1991-01-01

    Polyethylene and polypropylene were reacted with elemental fluorine under carefully controlled conditions to produce fluorocarbon polymers. Fluorination of polymer films resulted in fluorination of only the outer surfaces of the films, while the reaction of elemental fluorine with powdered hydrocarbon polymers produced perfluorocarbon polymers. Existing and newly developed techniques were used to characterize the fluorinated polymers. It was shown that the degree of fluorination was influenced by the surface area of the hydrocarbon material, the concentration, of the fluorine gas, and the time and temperature of fluorination. A fluidized-bed reactor used for the fluorination of polymer powders effectively increased the reaction rate. The surface tension and the oxygen permeability of the fluorinated polymers were studied. The surface tension of hydrocarbon polymers was not influenced by different solvents, but the surface tension of fluorinated polymers was affected by the type of solvent that was used. There were indications that the surface tension was affected by oxygen introduced into the polymer surface during fluorination. Fluorination lowered the permeability of oxygen through hydrocarbon polymers. 55 refs., 51 figs., 26 tabs

  7. A highly selective copper-indium bimetallic electrocatalyst for the electrochemical reduction of aqueous CO2to CO

    KAUST Repository

    Rasul, Shahid; Anjum, Dalaver H.; Jedidi, Abdesslem; Minenkov, Yury; Cavallo, Luigi; Takanabe, Kazuhiro

    2014-01-01

    The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes the competitive reduction of proton to form hydrogen during aqueous

  8. Molecularly imprinted polymer decorated nanoporous gold for highly selective and sensitive electrochemical sensors

    Science.gov (United States)

    Li, Yingchun; Liu, Yuan; Liu, Jie; Liu, Jiang; Tang, Hui; Cao, Cong; Zhao, Dongsheng; Ding, Yi

    2015-01-01

    Electrochemical nanosensors based on nanoporous gold leaf (NPGL) and molecularly imprinted polymer (MIP) are developed for pharmaceutical analysis by using metronidazole (MNZ) as a model analyte. NPGL, serving as the loading platform for MIP immobilization, possesses large accessible surface area with superb electric conductivity, while electrochemically synthesized MIP thin layer affords selectivity for specific recognition of MNZ molecules. For MNZ determination, the hybrid electrode shows two dynamic linear range of 5 × 10-11 to 1 × 10-9 mol L-1 and 1 × 10-9 to 1.4 × 10-6 mol L-1 with a remarkably low detection limit of 1.8 × 10-11 mol L-1 (S/N = 3). In addition, the sensor exhibits high binding affinity and selectivity towards MNZ with excellent reproducibility and stability. Finally, the reliability of MIP-NPGL for MNZ detection is proved in real fish tissue samples, demonstrating the potential for the proposed electrochemical sensors in monitoring drug and biological samples.

  9. 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

  10. Favoring the unfavored: Selective electrochemical nitrogen fixation using a reticular chemistry approach.

    Science.gov (United States)

    Lee, Hiang Kwee; Koh, Charlynn Sher Lin; Lee, Yih Hong; Liu, Chong; Phang, In Yee; Han, Xuemei; Tsung, Chia-Kuang; Ling, Xing Yi

    2018-03-01

    Electrochemical nitrogen-to-ammonia fixation is emerging as a sustainable strategy to tackle the hydrogen- and energy-intensive operations by Haber-Bosch process for ammonia production. However, current electrochemical nitrogen reduction reaction (NRR) progress is impeded by overwhelming competition from the hydrogen evolution reaction (HER) across all traditional NRR catalysts and the requirement for elevated temperature/pressure. We achieve both excellent NRR selectivity (~90%) and a significant boost to Faradic efficiency by 10 percentage points even at ambient operations by coating a superhydrophobic metal-organic framework (MOF) layer over the NRR electrocatalyst. Our reticular chemistry approach exploits MOF's water-repelling and molecular-concentrating effects to overcome HER-imposed bottlenecks, uncovering the unprecedented electrochemical features of NRR critical for future theoretical studies. By favoring the originally unfavored NRR, we envisage our electrocatalytic design as a starting point for high-performance nitrogen-to-ammonia electroconversion directly from water vapor-abundant air to address increasing global demand of ammonia in (bio)chemical and energy industries.

  11. Rapid and molecular selective electrochemical sensing of phthalates in aqueous solution

    KAUST Repository

    Zia, Asif I.

    2015-05-01

    Reported research work presents real time non-invasive detection of phthalates in spiked aqueous samples by employing electrochemical impedance spectroscopy (EIS) technique incorporating a novel interdigital capacitive sensor with multiple sensing thin film gold micro-electrodes fabricated on native silicon dioxide layer grown on semiconducting single crystal silicon wafer. The sensing surface was functionalized by a self-assembled monolayer of 3-aminopropyltrietoxysilane (APTES) with embedded molecular imprinted polymer (MIP) to introduce selectivity for the di(2-ethylhexyl) phthalate (DEHP) molecule. Various concentrations (1-100. ppm) of DEHP in deionized MilliQ water were tested using the functionalized sensing surface to capture the analyte. Frequency response analyzer (FRA) algorithm was used to obtain impedance spectra so as to determine sample conductance and capacitance for evaluation of phthalate concentration in the sample solution. Spectrum analysis algorithm interpreted the experimentally obtained impedance spectra by applying complex nonlinear least square (CNLS) curve fitting in order to obtain electrochemical equivalent circuit and corresponding circuit parameters describing the kinetics of the electrochemical cell. Principal component analysis was applied to deduce the effects of surface immobilized molecular imprinted polymer layer on the evaluated circuit parameters and its electrical response. The results obtained by the testing system were validated using commercially available high performance liquid chromatography diode array detector system.

  12. An Electrochemical Sensor Based on Novel Ion Imprinted Polymeric Nanoparticles for Selective Detection of Lead Ions

    Directory of Open Access Journals (Sweden)

    Masoud Ghanei-Motlagh

    1999-11-01

    Full Text Available In this study, the novel surface ion-imprinted polymer (IIP particles were prepared and applied as a electrode modifier in stripping voltammetric detection of lead(II ion. A carbon paste electrode (CPE modified with IIP nanoparticles and multi-walled carbon nanotubes (MWCNTs was used for accumulation of toxic lead ions. Various factors that govern on electrochemical signals including carbon paste composition, pH of the preconcentration solution, supporting electrolyte, stirring time, reduction potential and time were studied in detail. The best electrochemical response for Pb(II ions was obtained with a paste composition of 7% (w/w of lead IIP, 10% MWCNTs, 53% (w/w of graphite powder and 30% (w/w of paraffin oil using a solution of 0.1 mol L-1 acetat buffer solution (pH=4.5 with a extraction time of 15 min. A sensitive response for Pb(II ions in the concentration range of 3 to 55 µg L-1 was achived. The proposed electrochemical sensor showed low detection limit (0.5 µg L-1, remarkable selectivity and good reproducibility (RSD = 3.1%. Determination of lead(II content in different environmental water samples was also realized adopting graphite furnace atomic absorptions spectrometry (GF-AAS and the obtained results were satisfactory.

  13. 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.

  14. Single site porphyrine-like structures advantages over metals for selective electrochemical CO2 reduction

    DEFF Research Database (Denmark)

    Bagger, Alexander; Ju, Wen; Varela, Ana Sofia

    2017-01-01

    Currently, no catalysts are completely selective for the electrochemical CO2 Reduction Reaction (CO2RR). Based on trends in density functional theory calculations of reaction intermediates we find that the single metal site in a porphyrine-like structure has a simple advantage of limiting...... the competing Hydrogen Evolution Reaction (HER). The single metal site in a porphyrine-like structure requires an ontop site binding of hydrogen, compared to the hollow site binding of hydrogen on a metal catalyst surface. The difference in binding site structure gives a fundamental energy-shift in the scaling...... relation of ∼0.3eV between the COOH* vs. H* intermediate (CO2RR vs. HER). As a result, porphyrine-like catalysts have the advantage over metal catalyst of suppressing HER and enhancing CO2RR selectivity....

  15. Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

    Science.gov (United States)

    Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

    2016-02-05

    As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 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

  17. 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.

  18. Biomimetic supercontainers for size-selective electrochemical sensing of molecular ions

    Science.gov (United States)

    Netzer, Nathan L.; Must, Indrek; Qiao, Yupu; Zhang, Shi-Li; Wang, Zhenqiang; Zhang, Zhen

    2017-04-01

    New ionophores are essential for advancing the art of selective ion sensing. Metal-organic supercontainers (MOSCs), a new family of biomimetic coordination capsules designed using sulfonylcalix[4]arenes as container precursors, are known for their tunable molecular recognition capabilities towards an array of guests. Herein, we demonstrate the use of MOSCs as a new class of size-selective ionophores dedicated to electrochemical sensing of molecular ions. Specifically, a MOSC molecule with its cavities matching the size of methylene blue (MB+), a versatile organic molecule used for bio-recognition, was incorporated into a polymeric mixed-matrix membrane and used as an ion-selective electrode. This MOSC-incorporated electrode showed a near-Nernstian potentiometric response to MB+ in the nano- to micro-molar range. The exceptional size-selectivity was also evident through contrast studies. To demonstrate the practical utility of our approach, a simulated wastewater experiment was conducted using water from the Fyris River (Sweden). It not only showed a near-Nernstian response to MB+ but also revealed a possible method for potentiometric titration of the redox indicator. Our study thus represents a new paradigm for the rational design of ionophores that can rapidly and precisely monitor molecular ions relevant to environmental, biomedical, and other related areas.

  19. Electrochemical Impedance Sensors for Monitoring Trace Amounts of NO3 in Selected Growing Media.

    Science.gov (United States)

    Ghaffari, Seyed Alireza; Caron, William-O; Loubier, Mathilde; Normandeau, Charles-O; Viens, Jeff; Lamhamedi, Mohammed S; Gosselin, Benoit; Messaddeq, Younes

    2015-07-21

    With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance spectroscopy for monitoring trace amounts of NO3- in selected growing media. The nitrate sensor can be integrated to conventional microelectronics to perform online nitrate sensing continuously over a wide concentration range from 0.1 ppm to 100 ppm, with a response time of about 1 min, and feed data into a database for storage and analysis. The paper describes the structural design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the field testing of the nitrate sensor performed within tree nursery settings under ISO/IEC 17025 certifications.

  20. Electrochemical Impedance Sensors for Monitoring Trace Amounts of NO3 in Selected Growing Media

    Directory of Open Access Journals (Sweden)

    Seyed Alireza Ghaffari

    2015-07-01

    Full Text Available With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance spectroscopy for monitoring trace amounts of NO3− in selected growing media. The nitrate sensor can be integrated to conventional microelectronics to perform online nitrate sensing continuously over a wide concentration range from 0.1 ppm to 100 ppm, with a response time of about 1 min, and feed data into a database for storage and analysis. The paper describes the structural design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the field testing of the nitrate sensor performed within tree nursery settings under ISO/IEC 17025 certifications.

  1. 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.

  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.

  3. 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

  4. Selectivity control of carbonylation of methanol to dimethyl oxalate and dimethyl carbonate over gold anode by electrochemical potential.

    Science.gov (United States)

    Funakawa, Akiyasu; Yamanaka, Ichiro; Takenaka, Sakae; Otsuka, Kiyoshi

    2004-05-05

    New and unique electrocatalysis of gold for the carbonylation of methanol to dimethyl oxalate (DMO) and dimethyl carbonate (DMC) was found. The selectivity to DMO and DMC could be controlled over gold anode by electrochemical potential, as you like. Drastic changes of gold electrocatalysis was due to changes of the oxidation state of gold, Au0 or Au3+.

  5. Concentric-Electrode Organic Electrochemical Transistors: Case Study for Selective Hydrazine Sensing

    Directory of Open Access Journals (Sweden)

    Sébastien Pecqueur

    2017-03-01

    Full Text Available We report on hydrazine-sensing organic electrochemical transistors (OECTs with a design consisting of concentric annular electrodes. The design engineering of these OECTs was motivated by the great potential of using OECT sensing arrays in fields such as bioelectronics. In this work, poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS-based OECTs have been studied as aqueous sensors that are specifically sensitive to the lethal hydrazine molecule. These amperometric sensors have many relevant features for the development of hydrazine sensors, such as a sensitivity down to 10−5 M of hydrazine in water, an order of magnitude higher selectivity for hydrazine than for nine other water-soluble common analytes, the capability to entirely recover its base signal after water flushing, and a very low operation voltage. The specificity for hydrazine to be sensed by our OECTs is caused by its catalytic oxidation at the gate electrode, and enables an increase in the output current modulation of the devices. This has permitted the device-geometry study of the whole series of 80 micrometric OECT devices with sub-20-nm PEDOT:PSS layers, channel lengths down to 1 µm, and a specific device geometry of coplanar and concentric electrodes. The numerous geometries unravel new aspects of the OECT mechanisms governing the electrochemical sensing behaviours of the device—more particularly the effect of the contacts which are inherent at the micro-scale. By lowering the device cross-talk, micrometric gate-integrated radial OECTs shall contribute to the diminishing of the readout invasiveness and therefore further promote the development of OECT biosensors.

  6. 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.

  7. Synthesis and evaluation of fluorine-18-labeled SA4503 as a selective sigma1 receptor ligand for positron emission tomography

    International Nuclear Information System (INIS)

    Kawamura, Kazunori; Tsukada, Hideo; Shiba, Kazuhiro; Tsuji, Chieko; Harada, Norihiro; Kimura, Yuichi; Ishiwata, Kiichi

    2007-01-01

    The [ 18 F]fluoromethyl analog of the sigma 1 selective ligand 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (SA4503) ([ 18 F]FM-SA4503) was prepared and its potential evaluated for the in vivo measurement of sigma 1 receptors with positron emission tomography (PET). FM-SA4503 had selective affinity for the sigma 1 receptor ( K i for sigma 1 receptor, 6.4 nM; K i for sigma 2 receptor, 250 nM) that was compatible with the affinity of SA4503 ( K i for sigma 1 receptor, 4.4 nM; K i for sigma 2 receptor, 242 nM). [ 18 F]FM-SA4503 was synthesized by 18 F-fluoromethylation of O-demethyl SA4503 in the radiochemical yield of 2.9-16.6% at the end of bombardment with a specific activity of 37.8-283 TBq/mmol at the end of synthesis. In mice, the uptake of [ 18 F]FM-SA4503 in the brain was gradually increased for 30 min after injection, and then decreased. In the blocking study, brain uptake was significantly decreased by co-injection of haloperidol to 32% of control, and FM-SA4503 to 52% of control. In PET study of the monkey brain, high uptake was found in the cerebral cortex, thalamus and striatum. The radioactivity level of [ 18 F]FM-SA4503 in the brain regions gradually increased over a period of 120 min after injection, followed by a stable plateau phase until 180 min after injection. In pretreatment with haloperidol measurement of the monkey brain, the radioactivity level was 22-32% and 11-25% of the baseline at 60 and 180 min, respectively, after injection, suggesting high receptor-specific binding. [ 18 F]FM-SA4503 showed specific binding to sigma 1 receptors in mice and monkeys; therefore, [ 18 F]FM-SA4503 has the potential for mapping sigma 1 receptors in the brain

  8. An artificial self-sufficient cytochrome P450 directly nitrates fluorinated tryptophan analogs with a different regio-selectivity.

    Science.gov (United States)

    Zuo, Ran; Zhang, Yi; Huguet-Tapia, Jose C; Mehta, Mishal; Dedic, Evelina; Bruner, Steven D; Loria, Rosemary; Ding, Yousong

    2016-05-01

    Aromatic nitration is an immensely important industrial process to produce chemicals for a variety of applications, but it often suffers from multiple unsolved challenges. Enzymes as biocatalysts have been increasingly used for organic chemistry synthesis due to their high selectivity and environmental friendliness, but nitration has benefited minimally from the development of biocatalysis. In this work, we aimed to develop TxtE as practical biocatalysts for aromatic nitration. TxtE is a unique class I cytochrome P450 enzyme that nitrates the indole of l-tryptophan. To develop cost-efficient nitration processes, we fused TxtE with the reductase domains of CYP102A1 (P450BM3) and of P450RhF to create class III self-sufficient biocatalysts. The best engineered fusion protein was comparable with wild type TxtE in terms of nitration performance and other key biochemical properties. To demonstrate the application potential of the fusion enzyme, we nitrated 4-F-dl-tryptophan and 5-F-l-tryptophan in large scale enzymatic reactions. Tandem MS/MS and NMR analyses of isolated products revealed altered nitration sites. To our knowledge, these studies represent the first practice in developing biological nitration approaches and lay a solid basis to the use of TxtE-based biocatalysts for the production of valuable nitroaromatics. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Sequential electrochemical oxidation and site-selective growth of nanoparticles onto AFM probes.

    Science.gov (United States)

    Wang, Haitao; Tian, Tian; Zhang, Yong; Pan, Zhiqiang; Wang, Yong; Xiao, Zhongdang

    2008-08-19

    In this work, we reported an approach for the site-selective growth of nanoparticle onto the tip apex of an atomic force microscopy (AFM) probe. The silicon AFM probe was first coated with a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) through a chemical vapor deposition (CVD) method. Subsequently, COOH groups were selectively generated at the tip apex of silicon AFM probes by applying an appropriate bias voltage between the tip and a flat gold electrode. The transformation of methyl to carboxylic groups at the tip apex of the AFM probe was investigated through measuring the capillary force before and after electrochemical oxidation. To prepare the nanoparticle terminated AFM probe, the oxidized AFM probe was then immersed in an aqueous solution containing positive metal ions, for example, Ag+, to bind positive metal ions to the oxidized area (COOH terminated area), followed by chemical reduction with aqueous NaBH 4 and further development (if desired) to give a metal nanoparticle-modified AFM probe. The formation of a metal nanoparticle at the tip apex of the AFM probe was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA).

  10. Investigation of selective corrosion resistance of aged lean duplex stainless steel 2101 by non-destructive electrochemical techniques

    International Nuclear Information System (INIS)

    Gao Juan; Jiang Yiming; Deng Bo; Zhang Wei; Zhong Cheng; Li Jin

    2009-01-01

    Lean duplex stainless steel 2101 (LDX2101) shows wide application potential due to its better corrosion performance and lower cost than traditional 304 austenite steel. This paper investigates the effects of thermal aging treatments at 700 deg. C for various aging times up to 100 h on the selective corrosion resistance of LDX2101 by two non-destructive electrochemical measurements: double-loop electrochemical potentiokinetic reactivation (DL-EPR) and electrochemical impedance spectroscopy (EIS). The evolution of microstructure was examined by optical microscopy, SEM microscopy and X-ray diffraction techniques (XRD). The results showed that the two applied electrochemical measurements agreed very well. Both methods were able to reveal the relationship between microstructure and selective corrosion resistance, which was related to the formation of chromium- and molybdenum-depleted zones around the precipitates, especially the σ phase, during aging. Nevertheless, more information could be obtained using EIS methods, including the interfacial charge transfer reaction and the corrosion product adsorption process. The results suggest that the susceptibility of the aged alloy to selective corrosion is presumably codetermined by the formation of chromium- and molybdenum-depleted areas, as well as by the replenishment of them, in these areas from the bulk during aging.

  11. 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.

  12. Enhanced permeability, selectivity, and antifouling ability of CNTs/Al2O3 membrane under electrochemical assistance.

    Science.gov (United States)

    Fan, Xinfei; Zhao, Huimin; Liu, Yanming; Quan, Xie; Yu, Hongtao; Chen, Shuo

    2015-02-17

    Membrane filtration provides effective solutions for removing contaminants, but achieving high permeability, good selectivity, and antifouling ability remains a great challenge for existing membrane filtration technologies. In this work, membrane filtration coupled with electrochemistry has been developed to enhance the filtration performance of a CNTs/Al2O3 membrane. The as-prepared CNTs/Al2O3 membrane, obtained by coating interconnected CNTs on an Al2O3 substrate, presented good pore-size tunability, mechanical stability, and electroconductivity. For the removal of a target (silica spheres as a probe) with a size comparable to the membrane pore size, the removal efficiency and flux at +1.5 V were 1.1 and 1.5 times higher, respectively, than those without electrochemical assistance. Moreover, the membrane also exhibited a greatly enhanced removal efficiency for contaminants smaller than the membrane pores, providing enhancements of 4 orders of magnitude and a factor of 5.7 for latex particles and phenol, respectively. These results indicated that both the permeability and the selectivity of CNTs/Al2O3 membranes can be significantly improved by electrochemical assistance, which was further confirmed by the removal of natural organic matter (NOM). The permeate flux and NOM removal efficiency at +1.5 V were about 1.6 and 3.0 times higher, respectively, than those without electrochemical assistance. In addition, the lost flux of the fouled membrane was almost completely recovered by an electrochemically assisted backwashing process.

  13. Selective electrochemical detection of dopamine in a microfluidic channel on carbon nanoparticulate electrodes.

    Science.gov (United States)

    Rozniecka, Ewa; Jonsson-Niedziolka, Martin; Celebanska, Anna; Niedziolka-Jonsson, Joanna; Opallo, Marcin

    2014-06-07

    There is a continuous need for the construction of detection systems in microfluidic devices. In particular, electrochemical detection allows the separation of signals from the analyte and interfering substances in the potential domain. Here, a simple microfluidic device for the sensitive and selective determination of dopamine in the presence of interfering substances was constructed and tested. It employs a carbon nanoparticulate electrode allowing the separation of voltammetric signals of dopamine and common interfering substances (ascorbic acid and acetaminophen) both in quiescent conditions and in flow due to the electrocatalytic effect. These voltammograms were also successfully simulated. The limit of detection of dopamine detected by square wave voltammetry in 1 mM solutions of interfering substances in phosphate buffered saline is about 100 nM. In human serum a clear voltammetric signal could be seen for a 200 nM solution, sufficient to detect dopamine in the cerebral fluid. Flow injection analysis allows a decrease in the limit of detection down to 3.5 nM.

  14. A novel bi-enzyme electrochemical biosensor for selective and sensitive determination of methyl salicylate.

    Science.gov (United States)

    Fang, Yi; Umasankar, Yogeswaran; Ramasamy, Ramaraja P

    2016-07-15

    An amperometric sensor based on a bi-enzyme modified electrode was fabricated to detect methyl salicylate, a volatile organic compound released by pathogen-infected plants via systemic response. The detection is based on cascadic conversion reactions that result in an amperometric electrochemical signal. The bi-enzyme electrode is made of alcohol oxidase and horseradish peroxidase enzymes immobilized on to a carbon nanotube matrix through a molecular tethering method. Methyl salicylate undergoes hydrolysis to form methanol, which is consumed by alcohol oxidase to form formaldehyde while simultaneously reducing oxygen to hydrogen peroxide. The hydrogen peroxide will be further reduced to water by horseradish peroxidase, which results in an amperometric signal via direct electron transfer. The bi-enzyme biosensor was evaluated by cyclic voltammetry and constant potential amperometry using hydrolyzed methyl salicylate as the analyte. The sensitivity of the bi-enzyme biosensor as determined by cyclic voltammetry and constant potential amperometry were 112.37 and 282.82μAcm(-2)mM(-1) respectively, and the corresponding limits of detection were 22.95 and 0.98μM respectively. Constant potential amperometry was also used to evaluate durability, repeatability and interference from other compounds. Wintergreen oil was used for real sample study to establish the application of the bi-enzyme sensor for selective determination of plant pathogen infections. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. 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.

  16. A highly selective copper-indium bimetallic electrocatalyst for the electrochemical reduction of aqueous CO2to CO

    KAUST Repository

    Rasul, Shahid

    2014-12-23

    The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes the competitive reduction of proton to form hydrogen during aqueous CO2 conversion. A non-noble metal electrocatalyst based on a copper-indium (Cu-In) alloy that selectively converts CO2 to CO with a low overpotential is reported. The electrochemical deposition of In on rough Cu surfaces led to Cu-In alloy surfaces. DFT calculations showed that the In preferentially located on the edge sites rather than on the corner or flat sites and that the d-electron nature of Cu remained almost intact, but adsorption properties of neighboring Cu was perturbed by the presence of In. This preparation of non-noble metal alloy electrodes for the reduction of CO2 provides guidelines for further improving electrocatalysis.

  17. The surface chemical properties of multi-walled carbon nanotubes modified by thermal fluorination for electric double-layer capacitor

    Science.gov (United States)

    Jung, Min-Jung; Jeong, Euigyung; Lee, Young-Seak

    2015-08-01

    The surfaces of multi-walled carbon nanotubes (MWCNTs) were thermally fluorinated at various temperatures to enhance the electrochemical properties of the MWCNTs for use as electric double-layer capacitor (EDLC) electrodes. The fluorine functional groups were added to the surfaces of the MWCNTs via thermal fluorination. The thermal fluorination exposed the Fe catalyst on MWCNTs, and the specific surface area increased due to etching during the fluorination. The specific capacitances of the thermally fluorinated at 100 °C, MWCNT based electrode increased from 57 to 94 F/g at current densities of 0.2 A/g, respectively. This enhancement in capacitance can be attributed to increased polarization of the thermally fluorinated MWCNT surface, which increased the affinity between the electrode surface and the electrolyte ions.

  18. Reactions of BBr(n)(+) (n = 0--2) at fluorinated and hydrocarbon self-assembled monolayer surfaces: observations of chemical selectivity in ion--surface scattering.

    Science.gov (United States)

    Wade, N; Shen, J; Koskinen, J; Cooks, R G

    2001-07-01

    Ion-surface reactions involving BBr(n)(+) (n = 0--2) with a fluorinated self-assembled monolayer (F-SAM) surface were investigated using a multi-sector scattering mass spectrometer. Collisions of the B(+) ion yield BF(2)(+) at threshold energy with the simpler product ion BF(+)* appearing at higher collision energies and remaining of lower abundance than BF(2)(+) at all energies examined. In addition, the reactively sputtered ion CF(+) accompanies the formation of BF(2)(+) at low collision energies. These results stand in contrast with previous data on the ion-surface reactions of atomic ions with the F-SAM surface in that the threshold and most abundant reaction products in those cases involved the abstraction of a single fluorine atom. Gas-phase enthalpy data are consistent with BF(2)(+) being the thermodynamically favored product. The fact that the abundance of BF(2)(+) is relatively low and relatively insensitive to changes in collision energy suggests that this reaction proceeds through an entropically demanding intermediate at the vacuum--surface interface, one which involves interaction of the B(+) ion simultaneously with two fluorine atoms. By contrast with the reaction of B(+), the odd-electron species BBr(+)* reacts with the F-SAM surface to yield an abundant single-fluorine abstraction product, BBrF(+). Corresponding gas-phase ion--molecule experiments involving B(+) and BBr(+)* with C(6)F(14) also yield the products BF(+)* and BF(2)(+), but only in extremely low abundances and with no preference for double fluorine abstraction. Ion--surface reactions were also investigated for BBr(n)(+) (n = 0-2) with a hydrocarbon self-assembled monolayer (H-SAM) surface. Reaction of the B(+) ion and dissociative reactions of BBr(+)* result in the formation of BH(2)(+), while the thermodynamically less favorable product BH(+)* is not observed. Collisions of BBr(2)(+) with the H-SAM surface yield the dissociative ion-surface reaction products, BBrH(+) and BBrCH(3

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. Direct evidence of ionic fluxes across ion-selective membranes: a scanning electrochemical microscopic and potentiometric study.

    Science.gov (United States)

    Gyurcsányi, R E; Pergel, E; Nagy, R; Kapui, I; Lan, B T; Tóth, K; Bitter, I; Lindner, E

    2001-05-01

    Scanning electrochemical microscopy (SECM) supplemented with potentiometric measurements was used to follow the time-dependent buildup of a steady-state diffusion layer at the aqueous-phase boundary of lead ion-selective electrodes (ISEs). Differential pulse voltammetry is adapted to SECM for probing the local concentration profiles at the sample side of solvent polymeric membranes. Major factors affecting the membrane transport-related surface concentrations were identified from SECM data and the potentiometric transients obtained under different experimental conditions (inner filling solution composition, membrane thickness, surface pretreatment). The amperometrically determined surface concentrations correlated well with the lower detection limits of the lead ion-selective electrodes.

  4. A Nitrogen-Doped Carbon Catalyst for Electrochemical CO2 Conversion to CO with High Selectivity and Current Density.

    Science.gov (United States)

    Jhong, Huei-Ru Molly; Tornow, Claire E; Smid, Bretislav; Gewirth, Andrew A; Lyth, Stephen M; Kenis, Paul J A

    2017-03-22

    We report characterization of a non-precious metal-free catalyst for the electrochemical reduction of CO 2 to CO; namely, a pyrolyzed carbon nitride and multiwall carbon nanotube composite. This catalyst exhibits a high selectivity for production of CO over H 2 (approximately 98 % CO and 2 % H 2 ), as well as high activity in an electrochemical flow cell. The CO partial current density at intermediate cathode potentials (V=-1.46 V vs. Ag/AgCl) is up to 3.5× higher than state-of-the-art Ag nanoparticle-based catalysts, and the maximum current density is 90 mA cm -2 . The mass activity and energy efficiency (up to 48 %) were also higher than the Ag nanoparticle reference. Moving away from precious metal catalysts without sacrificing activity or selectivity may significantly enhance the prospects of electrochemical CO 2 reduction as an approach to reduce atmospheric CO 2 emissions or as a method for load-leveling in relation to the use of intermittent renewable energy sources. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Electrochemical activation and inhibition of neuromuscular systems through modulation of ion concentrations with ion-selective membranes

    Science.gov (United States)

    Song, Yong-Ak; Melik, Rohat; Rabie, Amr N.; Ibrahim, Ahmed M. S.; Moses, David; Tan, Ara; Han, Jongyoon; Lin, Samuel J.

    2011-12-01

    Conventional functional electrical stimulation aims to restore functional motor activity of patients with disabilities resulting from spinal cord injury or neurological disorders. However, intervention with functional electrical stimulation in neurological diseases lacks an effective implantable method that suppresses unwanted nerve signals. We have developed an electrochemical method to activate and inhibit a nerve by electrically modulating ion concentrations in situ along the nerve. Using ion-selective membranes to achieve different excitability states of the nerve, we observe either a reduction of the electrical threshold for stimulation by up to approximately 40%, or voluntary, reversible inhibition of nerve signal propagation. This low-threshold electrochemical stimulation method is applicable in current implantable neuroprosthetic devices, whereas the on-demand nerve-blocking mechanism could offer effective clinical intervention in disease states caused by uncontrolled nerve activation, such as epilepsy and chronic pain syndromes.

  6. Direct electron transfer: an approach for electrochemical biosensors with higher selectivity and sensitivity

    Directory of Open Access Journals (Sweden)

    Freire Renato S.

    2003-01-01

    Full Text Available The most promising approach for the development of electrochemical biosensors is to establish a direct electrical communication between the biomolecules and the electrode surface. This review focuses on advances, directions and strategies in the development of third generation electrochemical biosensors. Subjects covered include a brief description of the fundamentals of the electron transfer phenomenon and amperometric biosensor development (different types and new oriented enzyme immobilization techniques. Special attention is given to different redox enzymes and proteins capable of electrocatalyzing reactions via direct electron transfer. The analytical applications and future trends for third generation biosensors are also presented and discussed.

  7. 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.

  8. Electrochemical and spectroscopic studies of some less stable oxidation states of selected lanthanide and actinide elements

    International Nuclear Information System (INIS)

    Hobart, D.E.

    1981-06-01

    Simultaneous observation of electrochemical and spectroscopic properties (spectroelectrochemistry) at optically transparent electrodes (OTE's) was used to study some less stable oxidation states of selected lanthanide and actinide elements. Cyclic voltammetry at microelectrodes was used in conjunction with spectroelectrochemistry for the study of redox couples. Additional analytical techniques were used. The formal reduction potential (E 0 ') values of the M(III)/M(II) redox couples in 1 M KCl at pH 6 were -0.34 +- 0.01 V for Eu, -1.18 +- 0.01 V for Yb, and -1.50 +- 0.01 V for Sm. Spectropotentiostatic determination of E 0 ' for the Eu(III)/Eu(II) redox couple yielded a value of -0.391 +- 0.005 V. Spectropotentiostatic measurement of the Ce(IV)/Ce(III) redox couple in concentrated carbonate solution gave E 0 ' equal to 0.051 +- 0.005 V, which is about 1.7 V less positive than the E 0 ' value in noncomplexing solution. This same difference in potential was observed for the E 0 ' values of the Pr(IV)/Pr(III) and Tb(IV)/Tb(III) redox couples in carbonate solution, and thus Pr(IV) and Tb(IV) were stabilized in this medium. The U(VI)/U(V)/U(IV) and U(IV)/U(III) redox couples were studied in 1 M KCl at OTE's. Spectropotentiostatic measurement of the Np(VI)/Np(V) redox couple in 1 M HClO 4 gave an E 0 ' value of 1.140 +- 0.005 V. An E 0 ' value of 0.46 +- 0.01 V for the Np(VII)/Np(VI) couple was found by voltammetry. Oxidation of Am(III) was studied in concentrated carbonate solution, and a reversible cyclic voltammogram for the Am(IV)/Am(III) couple yielded E 0 ' = 0.92 +- 0.01 V in this medium; this value was used to estimate the standard reduction potential (E 0 ) of the couple as 2.62 +- 0.01 V. Attempts to oxidize Cm(III) in concentrated carbonate solution were not successful which suggests that the predicted E 0 value for the Cm(IV)/Cm(III) redox couple may be in error

  9. Highly selective NOx reduction for diesel engine exhaust via an electrochemical system

    DEFF Research Database (Denmark)

    Shao, Jing; Tao, Youkun; Kammer Hansen, Kent

    2016-01-01

    It is challenging to reduce the nitrogen oxides (NOx) in diesel engine exhaust due to the inhibiting effect of excess oxygen. In this study, a novel electrochemical deNOx system was developed, which eliminated the need for additional reducing materials or a sophisticated controlling system as used...

  10. Efficient and Selective Chemical Labeling of Electrochemically Generated Peptides Based on Spirolactone Chemistry

    NARCIS (Netherlands)

    Zhang, Tao; Niu, Xiaoyu; Yuan, Tao; Tessari, Marco; de Vries, Marcel P.; Permentier, Hjalmar P.; Bischoff, Rainer

    2016-01-01

    Specific digestion of proteins is an essential step for mass spectrometry-based proteomics, and the chemical labeling of the resulting peptides is often used for peptide enrichment or the introduction of desirable tags. Cleavage of the peptide bond following electrochemical oxidation of Tyr or Trp

  11. A novel immunochromatographic electrochemical biosensor for highly sensitive and selective detection of trichloropyridinol, a biomarker of exposure to chlorpyrifos.

    Science.gov (United States)

    Wang, Limin; Lu, Donglai; Wang, Jun; Du, Dan; Zou, Zhexiang; Wang, Hua; Smith, Jordan N; Timchalk, Charles; Liu, Fengquan; Lin, Yuehe

    2011-02-15

    We present a novel portable immunochromatographic electrochemical biosensor (IEB) for simple, rapid, and sensitive biomonitoring of trichloropyridinol (TCP), a metabolite biomarker of exposure to organophosphorus insecticides. Our new approach takes the advantage of immunochromatographic test strip for a rapid competitive immunoreaction and a disposable screen-printed carbon electrode for a rapid and sensitive electrochemical analysis of captured HRP labeling. Several key experimental parameters (e.g. immunoreaction time, the amount of HRP labeled TCP, concentration of the substrate for electrochemical measurements, and the blocking agents for the nitrocellulose membrane) were optimized to achieve a high sensitivity, selectivity and stability. Under optimal conditions, the IEB has demonstrated a wide linear range (0.1-100 ng/ml) with a detection limit as low as 0.1 ng/ml TCP. Furthermore, the IEB has been successfully applied for biomonitoring of TCP in the rat plasma samples with in vivo exposure to organophosphorus insecticides like Chlorpyrifos-oxon (CPF-oxon). The IEB thus opens up new pathways for designing a simple, rapid, clinically accurate, and quantitative tool for TCP detection, as well as holds a great promise for in-field screening of metabolite biomarkers, e.g., TCP, for humans exposed to organophosphorus insecticides. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. 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)

  13. Densely Packed, Ultra Small SnO Nanoparticles for Enhanced Activity and Selectivity in Electrochemical CO2 Reduction.

    Science.gov (United States)

    Gu, Jun; Héroguel, Florent; Luterbacher, Jeremy; Hu, Xile

    2018-03-05

    Controlling the selectivity in electrochemical CO 2 reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non-precious catalyst for CO 2 electroreduction, most Sn-based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO 2 reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra-small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. 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.)

  15. Ultrasensitive electrochemical aptasensor based on sandwich architecture for selective label-free detection of colorectal cancer (CT26) cells.

    Science.gov (United States)

    Hashkavayi, Ayemeh Bagheri; Raoof, Jahan Bakhsh; Ojani, Reza; Kavoosian, Saeid

    2017-06-15

    Colorectal cancer is one of the most common cancers in the world and has no effective treatment. Therefore, development of new methods for early diagnosis is instantly required. Biological recognition probes such as synthetic receptor and aptamer is one of the candidate recognition layers to detect important biomolecules. In this work, an electrochemical aptasensor was developed by fabricating an aptamer-cell-aptamer sandwich architecture on an SBA-15-3-aminopropyltriethoxysilane (SBA-15-pr-NH 2 ) and Au nanoparticles (AuNPs) modified graphite screen printed electrode (GSPE) surface for the selective, label-free detection of CT26 cancer cells. Based on the incubation of the thiolated aptamer with CT26 cells, the electron-transfer resistance of Fe (CN) 6 3-/4- redox couple increased considerably on the aptasensor surface. The results obtained from cyclic voltammetry and electrochemical impedance spectroscopy studies showed that the fabricated aptasensor can specifically identify CT26 cells in the concentration ranges of 10-1.0×10 5 cells/mL and 1.0×10 5 -6.0×10 6 cells/mL, respectively, with a detection limit of 2cells/mL. Applying the thiol terminated aptamer (5TR1) as a recognition layer led to a sensor with high affinity for CT26 cancer cells, compared to control cancer cells of AGS cells, VERO Cells, PC3 cells and SKOV-3 cells. Therefore a simple, rapid, label free, inexpensive, excellent, sensitive and selective electrochemical aptasensor based on sandwich architecture was developed for detection of CT26 Cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Highly selective and sensitive sensor based on an organic electrochemical transistor for the detection of ascorbic acid.

    Science.gov (United States)

    Zhang, Lijun; Wang, Guiheng; Wu, Di; Xiong, Can; Zheng, Lei; Ding, Yunsheng; Lu, Hongbo; Zhang, Guobing; Qiu, Longzhen

    2018-02-15

    In this study, an organic electrochemical transistor sensor (OECT) with a molecularly imprinted polymer (MIP)-modified gate electrode was prepared for the detection of ascorbic acid (AA). The combination of the amplification function of an OECT and the selective specificity of MIPs afforded a highly sensitive, selective OECT sensor. Cyclic voltammetry and electrochemical impedance spectroscopy measurements were carried out to monitor the stepwise fabrication of the modified electrodes and the adsorption capacity of the MIP/Au electrodes. Atomic force microscopy was employed for examining the surface morphology of the electrodes. Important detection parameters, pH and detection temperature were optimized. With the change in the relative concentration of AA from 1μM to 100μM, the MIP-OECT sensor exhibited a low detection limit of 10nM (S/N > 3) and a sensitivity of 75.3μA channel current change per decade under optimal conditions. In addition, the MIP-OECT sensor exhibited excellent specific recognition ability to AA, which prevented the interference from other structurally similar compounds (e.g., aspartic acid, glucose, uric acid, glycine, glutathione, H 2 O 2 ), and common metal ions (K + , Na + , Ca 2+ , Mg 2+ , and Fe 2+ ). In addition, a series of vitamin C beverages were analyzed to demonstrate the feasibility of the MIP-OECT sensor. Using the proposed principle, several other sensors with improved performance can be constructed via the modification of organic electrochemical transistors with appropriate MIP films. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Hydrogen evolution activity and electrochemical stability of selected transition metal carbides in concentrated phosphoric acid

    DEFF Research Database (Denmark)

    Tomás García, Antonio Luis; Jensen, Jens Oluf; Bjerrum, Niels J.

    2014-01-01

    phosphoric acid were investigated in a temperature range from 80 to 170°C. A significant dependence of the activities on temperature was observed for all five carbide samples. Through the entire temperature range Group 6 metal carbides showed higher activity than that of the Group 5 metal carbides......Alternative catalysts based on carbides of Group 5 (niobium and tantalum) and 6 (chromium, molybdenum and tungsten) metals were prepared as films on the metallic substrates. The electrochemical activities of these carbide electrodes towards the hydrogen evolution reaction (HER) in concentrated...

  18. 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.

  19. 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

  20. 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

  1. Utilization of a new optical sensor unit to monitor the electrochemical elimination of selected dyes in water

    Science.gov (United States)

    Valica, M.; Černá, T.; Hostin, S.

    2017-10-01

    This paper presents results obtained by developed optical sensor, which consist from multi-wavelength LED light source and two photodetectors capable of measuring the change in optical signal along two different optical paths (absorbance and reflectance measurements). Arduino microcomputer was used for light source management and optical signal data measuring and recording. Analytical validation of developed optical sensor is presented in this paper. The performance of the system has been tested with varying water solution of dyes (malachite green, methyl orange, trypan red). These results show strong correlations between the optical signal response and colour change from the dyes. Sensor was used for continual in-situ monitoring of electrochemical elimination of selected dyes (current density 15.7 mA cm-2, electrolyte volume 4 L and NaCl concentration 2 g L-1). Maximum decolorization level varies with each dye. For malachite green was obtain 92,7 % decolorization (25 min); methyl orange 90,8% (8,5 min) and trypan red 84,7% decolorization after 33 min of electrochemical treatment.

  2. Sensitive and selective electrochemical detection of chromium(VI) based on gold nanoparticle-decorated titania nanotube arrays.

    Science.gov (United States)

    Jin, Wei; Wu, Guosheng; Chen, Aicheng

    2014-01-07

    Owing to the severe toxicity and mobility of Cr(VI) in biological and environmental systems, it is of great importance to develop convenient and reliable methods for its detection. Here we report on a facile and effective electrochemical technique for monitoring Cr(VI) concentrations based on the utilization of Au nanoparticle-decorated titania nanotubes (TiO2NTs) grown on a titanium substrate. It was found that the electrochemical reduction of Cr(VI) at the Ti/TiO2NT/Au electrode exhibited an almost 23 fold improvement in activity as compared to a polycrystalline gold electrode, due to its nanoparticle/nanotubular heterojunction infrastructure. As a result, the Ti/TiO2NT/Au electrode demonstrated a wide linear concentration range from 0.10 μM to 105 μM, a low detection limit of 0.03 μM, and a high sensitivity of 6.91 μA μM(-1) Cr(VI) via amperometry, satisfying the detection requirements of the World Health Organization (WHO). Moreover, the Ti/TiO2NT/Au electrode exhibited good resistance against interference from coexisting Cr(III) and other metal ions, and excellent recovery for Cr(VI) detection in both tap and lake water samples. These attributes suggest that this hybrid sensor has strong potential in applications for the selective detection of Cr(VI).

  3. Improved performance and safety of lithium ion cells with the use of fluorinated carbonate-based electrolytes

    Science.gov (United States)

    Smart, M. C.; Ratnakumar, B. V.; Ryan, V. S.; Surampudi, S.; Prakashi, G. K. S.; Hu, J.; Cheung, I.

    2002-01-01

    There has been increasing interest in developing lithium-ion electrolytes that possess enhanced safety characteristics, while still able to provide the desired stability and performance. Toward this end, our efforts have been focused on the development of lithium-ion electrolytes which contain partially and fully fluorinated carbonate solvents. The advantage of using such solvents is that they possess the requisite stability demonstrated by the hydrocarbon-based carbonates, while also possessing more desirable physical properties imparted by the presence of the fluorine substituents, such as lower melting points, increased stability toward oxidation, and favorable SEI film forming Characteristics on carbon. Specifically, we have demonstrated the beneficial effect of electrolytes which contain the following fluorinated carbonate-based solvents: methyl 2,2,2-trifluoroethyl carbonate (MTFEC), ethyl-2,2,2 trifluoroethyl carbonate (ETFEC), propyl 2,2,2-trifluoroethyl carbonate (PTFEC), methyl-2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (MHFPC), ethyl- 2,2,2,2',2',2' -hexafluoro-i-propyl carbonate (EHFPC), and di-2,2,2-trifluoroethyl carbonate (DTFEC). These solvents have been incorporated into multi-component ternary and quaternary carbonate-based electrolytes and evaluated in lithium-carbon and carbon-LiNio.8Coo.202 cells (equipped with lithium reference electrodes). In addition to determining the charge/discharge behavior of these cells, a number of electrochemical techniques were employed (i.e., Tafel polarization measurements, linear polarization measurements, and electrochemical impedance spectroscopy (EIS)) to further characterize the performance of these electrolytes, including the SEI formation characteristics and lithium intercalatiodde-intercalation kinetics. In addition to their evaluation in experimental cells, cyclic voltammetry (CV) and conductivity measurements were performed on select electrolyte formulations to further our understanding of the trends

  4. RNA aptamer-based electrochemical biosensor for selective and label-free analysis of dopamine

    DEFF Research Database (Denmark)

    Farjami, Elahe; Campos, Rui; Nielsen, Jesper Sejrup

    2013-01-01

    , including dopamine precursors and metabolites and other neurotransmitters (NT). Here we report an electrochemical RNA aptamer-based biosensor for analysis of dopamine in the presence of other NT. The biosensor exploits a specific binding of dopamine by the RNA aptamer, immobilized at a cysteamine......, norepinephrine, 3,4-dihydroxy-phenylalanine (l-DOPA), 3,4-dihydroxyphenylacetic acid (DOPAC), methyldopamine, and tyramine, which gave negligible signals under conditions of experiments (electroanalysis at 0.185 V vs Ag/AgCl). The interference from ascorbic and uric acids was eliminated by application...... as a general strategy not to restrict the conformational freedom and binding properties of surface-bound aptamers and, thus, be applicable for the development of other aptasensors...

  5. Selective Electrochemical Reduction of Carbon Dioxide to Ethanol on a Boron- and Nitrogen-Co-doped Nanodiamond.

    Science.gov (United States)

    Liu, Yanming; Zhang, Yujing; Cheng, Kai; Quan, Xie; Fan, Xinfei; Su, Yan; Chen, Shuo; Zhao, Huimin; Zhang, Yaobin; Yu, Hongtao; Hoffmann, Michael R

    2017-12-04

    Electrochemical reduction of CO 2 to ethanol, a clean and renewable liquid fuel with high heating value, is an attractive strategy for global warming mitigation and resource utilization. However, converting CO 2 to ethanol remains great challenge due to the low activity, poor product selectivity and stability of electrocatalysts. Here, the B- and N-co-doped nanodiamond (BND) was reported as an efficient and stable electrode for selective reduction of CO 2 to ethanol. Good ethanol selectivity was achieved on the BND with high Faradaic efficiency of 93.2 % (-1.0 V vs. RHE), which overcame the limitation of low selectivity for multicarbon or high heating value fuels. Its superior performance was mainly originated from the synergistic effect of B and N co-doping, high N content and overpotential for hydrogen evolution. The possible pathway for CO 2 reduction revealed by DFT computation was CO 2 →*COOH→*CO→*COCO→*COCH 2 OH→*CH 2 OCH 2 OH→CH 3 CH 2 OH. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Electrochemically modified carbon fiber bundles as selective sorbent for online solid-phase microextraction of sulfonamides

    International Nuclear Information System (INIS)

    Ling, Xu; Zhang, Wenpeng; Chen, Zilin

    2016-01-01

    The authors show that carbon fiber bundles electrochemically modified with the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is a viable sorbent for online solid-phase microextraction (SPME) of the sulfonamides (sulfadiazine, sulfadimidine and sulfamethoxazole) prior to their determination by HPLC. The fibers were packed in a tube loop made from polyether ether ketone (PEEK) that was coupled to the HPLC system for online SPME. Preconcentration factors can reach values of up to 300, and the limit of detection (at an S/N ration of 3) can be as low as 0.05 ng⋅mL −1 . The method was applied to the analysis of the sulfonamides in spiked rat plasma with intra-day and inter-day RSDs of <3.33 and <4.57 %, and with recoveries in the range from 91.7 to 97.8 % in spiked plasma. The in-tube SPME was also applied to the determination of the 3 sulfonamides in rat plasma after oral administration (tablet powder) with high sensitivity. In addition to its efficient extraction, the PEEK tube based SPME has chemical and mechanical stability under even harsh conditions. (author)

  7. Fluorination by fusion

    International Nuclear Information System (INIS)

    Gray, J.H.

    1986-01-01

    LECO crucibles and incinerator ash are two waste categories that cannot be discarded due to the presence of insoluble transuranics. Current chemical processing methods are not too effective, requiring a number of repeated operations in order to dissolve more than half the transuranics. An alternate dissolution approach has been developed involving the use of ammonium bifluoride. Low temperature fusion of the waste with ammonium bifluoride is followed by dissolution of the fused material in boiling nitric acid solutions. Greater than 60% of the transuranics contained in LECO crucibles and greater than 95% of the transuranics mixed with the incinerator ash are dissolved after a single fusion and dissolution step. Fluorination of the transuranics along with other impurities appears to render the waste material soluble in nitric acid

  8. Evaluation of fluorine-18-labeled alkylating agents as potential synthons for the labeling of oligonucleotides

    NARCIS (Netherlands)

    de Vries, EFJ; Vroegh, J; Elsinga, PH; Vaalburg, W

    Six fluorine-18-labeled alkylating agents were selected as potentially suitable synthons for the labeling of antisense oligonucleotides. The selected synthons were evaluated in a model reaction with the monomer adenosine 5'-O-thiomonophosphate. Of these synthons,

  9. Rapid and molecular selective electrochemical sensing of phthalates in aqueous solution

    KAUST Repository

    Zia, Asif I.; Mukhopadhyay, Subhas Chandra; Yu, Paklam; Al-Bahadly, Ibrahim H.; Gooneratne, Chinthaka Pasan; Kosel, Jü rgen

    2015-01-01

    molecular imprinted polymer (MIP) to introduce selectivity for the di(2-ethylhexyl) phthalate (DEHP) molecule. Various concentrations (1-100. ppm) of DEHP in deionized MilliQ water were tested using the functionalized sensing surface to capture the analyte

  10. 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

  11. 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.

  12. Microfluidic sensor for ultra high redox cycling amplification for highly selective electrochemical measurements

    NARCIS (Netherlands)

    Odijk, Mathieu; Straver, Martin; Olthuis, Wouter; van den Berg, Albert

    2011-01-01

    In this contribution a SU8/glass-based microfluidic sensor is described with two closely spaced parallel electrodes for highly selective measurements using the redox cycling (RC) effect. Using this sensor, a RC amplification of ~2000x is measured using the ferrocyanide redox couple, which is much

  13. 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

  14. Selective electrochemical sensor for copper (II) ion based on chelating ionophores

    International Nuclear Information System (INIS)

    Singh, Ashok Kumar; Mehtab, Sameena; Jain, Ajay Kumar

    2006-01-01

    Plasticized membranes using 3-(2-pyridinyl)-2H-pyrido[1,2,-a]-1,3,5-triazine-2,4(3H)-dithione (L 1 ) and acetoacetanilide (L 2 ) have been prepared and explored as Cu 2+ -selective sensors. Effect of various plasticizers, viz. chloronaphthalene (China), benzyl acetate (BA), o-nitrophenyloctyl ether (o-NPOE), and anion excluders, sodium tetraphenylborate (NaTPB) and oleic acid (OA) was studied in detail and improved performance was observed at several instances. Optimum performance was observed with dithione derivative (L 1 ) having a membrane composition of L 1 (5):PVC (120):o-NPOE (240):OA (10). The sensor works satisfactorily in the concentration range 5.0 x 10 -8 to 1.0 x 10 -2 M (detection limit 4.0 x 10 -8 M) with a Nernstian slope of 29.5 mV decade -1 of activity. Wide pH range (3.0-9.5), fast response time (12 s), non-aqueous tolerance (up to 20%) and adequate shelf life (4 months) indicate the vital utility of the proposed sensor. The potentiometric selectivity coefficient values as determined by match potential method (MPM) indicate good response for Cu 2+ in presence of interfering ions. The proposed electrode comparatively shows good selectivity with respect to alkali, alkaline earth, transition and some rare earth metals ions. The electrode was used for the determination of copper in different milk powder, water samples and as indicator electrode in potentiometric titration of copper ion with EDTA

  15. Phosphorus and Fluorine - The Union for Bioregulators

    Directory of Open Access Journals (Sweden)

    Romanenko, V.

    2007-06-01

    Full Text Available The review demonstrates the very high efficiency and usefulness of the fluorine-phosphorus combination in order to synthesize organic molecules for purposes of modern life science. For biochemistry, the "P-F-union" in" biomolecules enables investigation of the enzyme structure and mechanism of action more correctly, as well as creation of new anti-body enzymes. Enhancing or regulation of inhibitor properties of these compounds, their stability or selectivity allows creation of new drugs for treatment of numerous serious diseases, especially viral infections and cancer.

  16. The electrochemical selective reduction of NO using CoSe2@CNTs hybrid.

    Science.gov (United States)

    Liu, Hui; Xiang, Kaisong; Yang, Bentao; Xie, Xiaofeng; Wang, Dongli; Zhang, Cong; Liu, Zhilou; Yang, Shu; Liu, Cao; Zou, Jianping; Chai, Liyuan

    2017-06-01

    Converting the NO from gaseous pollutant into NH 4 + through electrocatalytical reduction using cost-effective materials holds great promise for pollutant purifying and resources recycling. In this work, we developed a highly selective and stable catalyst CoSe 2 nanoparticle hybridized with carbon nanotubes (CoSe 2 @CNTs). The CoSe 2 @CNTs hybrid catalysts performed an extraordinary high selectivity for NH 4 + formation in NO electroreduction with minimal N 2 O production and H 2 evolution. The specific spatial structure of CoSe 2 is conductive to the predominant formation of N-H bond between the N from adsorbed NO and H and inhibition of N-N formation from adjacent adsorbed NO. It was also the first time to convert the coordinated NO into NH 4 + using non-noble metal catalysis. Moreover, the original concept of employing CoSe 2 as eletrocatalyst for NO hydrogenation presented in this work can broaden horizons and provide new dimensions in the design of new highly efficient catalysts for NH 4 + synthesis in aqueous solution.

  17. Carbon nanotubes-functionalized urchin-like In2S3 nanostructure for sensitive and selective electrochemical sensing of dopamine

    International Nuclear Information System (INIS)

    Yang, Z.; Huang, X.; Li, J.; Zhang, Y.; Yu, S.; Xu, Q.; Hu, X.

    2012-01-01

    Urchin-like In 2 S 3 nanostructures were functionalized with multi-walled carbon nanotubes (MWCNTs) and deposited on a glassy carbon electrode (GCE) to obtain a new kind of sensor for dopamine (DA). The new electrode was characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, cyclic voltammetry and differential pulse voltammetry. It is found that the current response toward DA is significantly enhanced compared to that of a bare GCE or a GCE modified with MWCNTs. The peak separation between DA and ascorbic acid (AA) is up to 225 mV. The new electrode also has improved selectivity for DA over AA compared to the bare electrode. The new DA sensor has a wide linear range (0.5-300 μM), high sensitivity (594.9 μA mM -1 cm -2 ) and low detection limit (0.1 μM). CNTs wrapped on urchin-like nanostructures remarkable improve its electrocatalytic activity and thus provide a promising strategy to develop excellent composite materials for electrochemical sensing. (author)

  18. Electrochemical selective detection of dopamine on microbial carbohydrate-doped multiwall carbon nanotube-modified electrodes.

    Science.gov (United States)

    Jin, Joon-Hyung; Cho, Eunae; Jung, Seunho

    2010-03-01

    Microbial carbohydrate-doped multiwall carbon nanotube (MWNT)-modified electrodes were prepared for the purpose of determining if 4-(2-aminoethyl)benzene-1,2-diol (3,4-dihydroxyphenylalanine; dopamine) exists in the presence of 0.5 mM ascorbic acid, a representative interfering agent in neurotransmitter detection. The microbial carbohydrate dopants were alpha-cyclosophorohexadecaose (alpha-C16) from Xanthomonas oryzae and cyclic-(1 --> 2)-beta-d-glucan (Cys) from Rhizobium meliloti. The cyclic voltammetric responses showed that the highest sensitivity (5.8 x 10(-3) mA cm(-2) microM(-1)) is attained with the Cys-doped MWNT-modified ultra-trace carbon electrode, and that the alpha-C16-doped MWNT-modified glassy carbon electrode displays the best selectivity to dopamine (the approximate peak potential separation is 310 mV).

  19. Electrochemical investigation of gold nanoparticles incorporated zinc based metal-organic framework for selective recognition of nitrite and nitrobenzene

    International Nuclear Information System (INIS)

    Yadav, Dharmendra Kumar; Ganesan, Vellaichamy; Sonkar, Piyush Kumar; Gupta, Rupali; Rastogi, Pankaj Kumar

    2016-01-01

    Highlights: • Gold nanoparticles incorporated zinc based metal-organic framework is synthesized. • It electro-catalyzes nitrite oxidation and nitrobenzene reduction. • Nitrite and nitrobenzene is determined with high sensitivity. • Hydrodynamic voltammetry studies of nitrite oxidation and nitrobenzene reduction are reported. - Abstract: An electrochemical sensing platform which comprises gold nanoparticles (Au NPs) incorporated zinc based metal-organic framework (MOF-5) is developed for the sensitive determination of nitrite and nitrobenzene. MOF-5 and Au NPs incorporated MOF-5 (Au-MOF-5) are synthesized and characterized by UV-vis absorption, powder X-ray diffraction, FT-IR, scanning electron microscopy with energy dispersive X-ray analysis and elemental mapping, transmission electron microscopy and atomic force microscopy. Oxidation of nitrite is effectively electrocatalyzed at Au-MOF-5 with significant increase in oxidation current (41 and 38% in comparison with bare glassy carbon (GC) and MOF-5 coated GC (GC/MOF-5) electrodes, respectively) and with considerable decrease in the oxidation potential (0. 17 and 0.25 V in comparison with bare GC and GC/MOF-5 electrodes, respectively). The electrocatalytic reduction of nitrobenzene at GC/Au-MOF-5 is confirmed by an appreciable increase in the reduction current (79 and 36% in comparison with bare GC and GC/MOF-5 electrodes, respectively) and a small shift in the reduction potential (20 mV in comparison with GC/MOF-5). The detection limit is calculated as 1.0 μM with a sensitivity of 0.23 μAμM"−"1 cm"−"2 for nitrite and 15.3 μM with a sensitivity of 0.43 μAμM"−"1cm"−"2 for nitrobenzene determinations. The Au-MOF-5 based electrochemical sensing platform shows high stability and selectivity even in the presence of several interferences (including phenols, inorganic ions and biologically important molecules) with a broad calibration range. Certain kinetic parameters of nitrite oxidation and

  20. 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.

  1. 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.

  2. Role of the adsorbed oxygen species in the selective electrochemical reduction of CO{sub 2} to alcohols and carbonyls on copper electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Le Duff, Cecile S.; Lawrence, Matthew J.; Rodriguez, Paramaconi [School of Chemistry, University of Birmingham, Edgbaston (United Kingdom)

    2017-10-09

    The electrochemical reduction of CO{sub 2} into fuels has gained significant attention recently as source of renewable carbon-based fuels. The unique high selectivity of copper in the electrochemical reduction of CO{sub 2} to hydrocarbons has called much interest in discovering its mechanism. In order to provide significant information about the role of oxygen in the electrochemical reduction of CO{sub 2} on Cu electrodes, the conditions of the surface structure and the composition of the Cu single crystal electrodes were controlled over time. This was achieved using pulsed voltammetry, since the pulse sequence can be programmed to guarantee reproducible initial conditions for the reaction at every fraction of time and at a given frequency. In contrast to the selectivity of CO{sub 2} reduction using cyclic voltammetry and chronoamperometric methods, a large selection of oxygenated hydrocarbons was found under alternating voltage conditions. Product selectivity towards the formation of oxygenated hydrocarbon was associated to the coverage of oxygen species, which is surface-structure- and potential-dependent. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Role of the adsorbed oxygen species in the selective electrochemical reduction of CO_2 to alcohols and carbonyls on copper electrodes

    International Nuclear Information System (INIS)

    Le Duff, Cecile S.; Lawrence, Matthew J.; Rodriguez, Paramaconi

    2017-01-01

    The electrochemical reduction of CO_2 into fuels has gained significant attention recently as source of renewable carbon-based fuels. The unique high selectivity of copper in the electrochemical reduction of CO_2 to hydrocarbons has called much interest in discovering its mechanism. In order to provide significant information about the role of oxygen in the electrochemical reduction of CO_2 on Cu electrodes, the conditions of the surface structure and the composition of the Cu single crystal electrodes were controlled over time. This was achieved using pulsed voltammetry, since the pulse sequence can be programmed to guarantee reproducible initial conditions for the reaction at every fraction of time and at a given frequency. In contrast to the selectivity of CO_2 reduction using cyclic voltammetry and chronoamperometric methods, a large selection of oxygenated hydrocarbons was found under alternating voltage conditions. Product selectivity towards the formation of oxygenated hydrocarbon was associated to the coverage of oxygen species, which is surface-structure- and potential-dependent. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Electrochemical sensor based on a carbon nanotube-modified imprinted sol–gel for selective and sensitive determination of β2-agonists

    International Nuclear Information System (INIS)

    Xu, Wei; Liu, Ping; Guo, Chunhui; Dong, Chao; Zhang, Xiuhua; Wang, Shengfu

    2013-01-01

    We describe a molecularly imprinted electrochemical sensor for selective and sensitive determination of β2-agonists. It is making use of a combination of single-wall carbon nanotubes (SWNTs) with a molecularly imprinted sol–gel. The SWNTs were introduced in order to enhance electron transport and sensitivity. The imprinted sol–gel film with its specific binding sites acts as a selective recognition element and as a preconcentrator for β 2 -agonists. The morphology of the imprinted film was characterized by scanning electron microscopy. The optimized sensor displays high sensitivity and excellent selectivity for the β 2 -agonists as shown for their determination in human serum samples. (author)

  5. Rhombohedral iron trifluoride with a hierarchized macroporous/mesoporous texture from gaseous fluorination of iron disilicide

    Energy Technology Data Exchange (ETDEWEB)

    Guérin, Katia, E-mail: katia.araujo_da_silva@univ-bpclermont.fr [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, F-63171 Aubière (France); Delbègue, Diane; Louvain, Nicolas; Doubtsof, Léa; Hamwi, André [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, F-63171 Aubière (France); Laik, Barbara; Pereira-Ramos, Jean-Pierre [Université Paris Est Créteil, Institut de Chimie et des Matériaux Paris-Est, UMR CNRS 7182, Thiais (France); Tahar-sougrati, Moulay; Jumas, Jean-Claude [Université Montpellier II, Institut Charles Gerhardt de Montpellier, UMR CNRS 5253, Montpellier (France); Willmann, Patrick; Cénac-Morthe, Céline [Centre National d' Etudes Spatiales, Toulouse (France)

    2016-04-15

    Stable low temperature rhombohedral iron trifluoride has been obtained by the fluorination under the pure fluorine gas of iron disilicide. The combination of both unusual fluorination process and precursor avoids to get unhydrated crystalline FeF{sub 3} particles and allows the formation of hierarchized channels of mesoporous/macroporous texture favorable for lithium diffusion. The fluorination mechanism proceeds by temperature steps from the formation, for a fluorination temperature below 200 °C, of an amorphous phase and an intermediate iron difluoride identified mainly by {sup 57}Fe Mössbauer spectroscopy before getting, as soon as a fluorination temperature of 260 °C is reached, the rhombohedral FeF{sub 3}. Both amorphous and crystallized samples display good ability for electrochemical process when used as cathode in lithium-ion battery. The low diameter of rhombohedral structure channels is balanced by an appropriate mesoporous texture and a capacity of 225 mAh.g{sup −1} after 5 cycles for a discharge cut-off of 2.5 V vs. Li{sup +}/Li at a current density of C/20 has been obtained and stabilized at 95 mAh.g{sup −1} after 116 cycles. - Highlights: • We investigated the synthesis of rhombohedral FeF{sub 3} by solid–gas reaction from iron disilicide. • We demonstrated that depending on the fluorination temperature various phases are stabilized. • We got a hierarchized macroporous/mesoporous texture. • We studied the electrochemical performances of amorphous and crystallized FeF{sub 3}. • Crystallized FeF{sub 3} presents a high faradic yield at first cycle focusing on insertion process.

  6. Highly Stereoselective Gold-Catalyzed Coupling of Diazo Reagents and Fluorinated Enol Silyl Ethers to Tetrasubstituted Alkenes.

    Science.gov (United States)

    Liao, Fu-Min; Cao, Zhong-Yan; Yu, Jin-Sheng; Zhou, Jian

    2017-02-20

    We report a highly stereoselective synthesis of all-carbon or fluorinated tetrasubstituted alkenes from diazo reagents and fluorinated enol silyl ethers, using C-F bond as a synthetic handle. Cationic Au I catalysis plays a key role in this reaction. Remarkable fluorine effects on the reactivity and selectivity was also observed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. E- or Z-Selective synthesis of 4-fluorovinyl-1,2,3-triazoles with fluorinated second-generation Julia-Kocienski reagents.

    Science.gov (United States)

    Kumar, Rakesh; Singh, Govindra; Todaro, Louis J; Yang, Lijia; Zajc, Barbara

    2015-02-07

    A highly modular approach to N-substituted 4-(1-fluorovinyl)triazoles is described. In situ desilylation and Cu-catalyzed ligation reaction of TMS-protected α-fluoropropargyl benzothiazole sulfone with aryl, alkyl, and metallocenyl azides furnished second-generation Julia-Kocienski reagents in good to excellent yields. Condensation reactions of these reagents with aldehydes can be tuned to yield E or Z-alkenes selectively. Under mild conditions with DBU as the base, reactions of aldehydes furnished E-alkenes as the major isomer. On the other hand, in condensation reactions with LHMDS as the base and in appropriate solvents, both aldehydes and ketones reacted to yield fluoroalkenes with Z-selectivity. Stereochemical assignment of E/Z olefins obtained in the reaction of a ketone with two Julia reagents was performed via X-ray crystallographic analysis and comparisons of NMR data. The method allows efficient and ready diversification of the N1-substituent and substituents at the double bond.

  8. Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles.

    Science.gov (United States)

    Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C

    2014-07-01

    For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1-30.0 μM and 30.0-330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. Copyright © 2014. Published by Elsevier B.V.

  9. Electrochemical Partial Reforming of Ethanol into Ethyl Acetate Using Ultrathin Co3O4 Nanosheets as a Highly Selective Anode Catalyst.

    Science.gov (United States)

    Dai, Lei; Qin, Qing; Zhao, Xiaojing; Xu, Chaofa; Hu, Chengyi; Mo, Shiguang; Wang, Yu Olivia; Lin, Shuichao; Tang, Zichao; Zheng, Nanfeng

    2016-08-24

    Electrochemical partial reforming of organics provides an alternative strategy to produce valuable organic compounds while generating H2 under mild conditions. In this work, highly selective electrochemical reforming of ethanol into ethyl acetate is successfully achieved by using ultrathin Co3O4 nanosheets with exposed (111) facets as an anode catalyst. Those nanosheets were synthesized by a one-pot, templateless hydrothermal method with the use of ammonia. NH3 was demonstrated critical to the overall formation of ultrathin Co3O4 nanosheets. With abundant active sites on Co3O4 (111), the as-synthesized ultrathin Co3O4 nanosheets exhibited enhanced electrocatalytic activities toward water and ethanol oxidations in alkaline media. More importantly, over the Co3O4 nanosheets, the electrooxidation from ethanol to ethyl acetate was so selective that no other oxidation products were yielded. With such a high selectivity, an electrolyzer cell using Co3O4 nanosheets as the anode electrocatalyst and Ni-Mo nanopowders as the cathode electrocatalyst has been successfully built for ethanol reforming. The electrolyzer cell was readily driven by a 1.5 V battery to achieve the effective production of both H2 and ethyl acetate. After the bulk electrolysis, about 95% of ethanol was electrochemically reformed into ethyl acetate. This work opens up new opportunities in designing a material system for building unique devices to generate both hydrogen and high-value organics at room temperature by utilizing electric energy from renewable sources.

  10. 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

  11. A composite material based on nanoparticles of yttrium (III) oxide for the selective and sensitive electrochemical determination of acetaminophen

    International Nuclear Information System (INIS)

    Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

    2016-01-01

    An electrochemical sensor was prepared by modifying a glassy carbon electrode (GCE) with a composite of yttrium (III) oxide nanoparticles (Y_2O_3NPs) and carbon nanotubes (CNTs) for the determination of acetaminophen (ACT). Compared with a bare GCE and CNTs/GCE, the Y_2O_3NPs/CNTs/GCE exhibited a well-defined redox couple for ACT and highly enhanced the current response. The separations in the anodic and cathodic peak potentials (ΔE_p) for ACT were 552 mV, 24 mV and 10 mV at ba4re GCE, CNTs/GCE and Y_2O_3NPs/CNTs/GCE, respectively. The observation of only 10 mV of ΔE_p for ACT at Y_2O_3NPs/CNTs/GCE was a clear indication of a great acceleration of the electrode process compared to bare GCE and GCE modified with CNTs. Also, L-ascorbic acid (L-AA) and L-tyrosine (L-TRY) did not interfere with the selective determination of ACT. Square wave voltammetry (SWV) was performed for the quantification of ACT. A linear plot was obtained for current responses versus the concentrations of ACT over the range from 1.0 × 10"−"1"0 to 1.8 × 10"−"8 M with a detection limit of 3.0 × 10"−"1"1 M (based on 3S_b/m). The proposed composite material provided high electrocatalytic activity, improved voltammetric behavior, good selectivity and good reproducibility. The accurate quantification of ACT makes the proposed electrode of great interest for the public health. - Highlights: • A voltammetric sensor based on yttrium oxide was prepared for the detection of ACT. • The proposed electrode has greatly accelerated the voltammetric process of ACT. • A detection limit of 0.03 nM was obtained for ACT. • The proposed electrode exhibited great selectivity for ACT in the presence of L-AA and L-TRY. • The composite material exhibited high sensitivity, good stability and excellent reproducibility.

  12. A composite material based on nanoparticles of yttrium (III) oxide for the selective and sensitive electrochemical determination of acetaminophen

    Energy Technology Data Exchange (ETDEWEB)

    Baytak, Aysegul Kutluay [Department of Medical Laboratory, Vocational School of Health Services, Harran University, Şanlıurfa 63510 (Turkey); Teker, Tugce; Duzmen, Sehriban [Department of Chemistry, Harran University, Şanlıurfa 63510 (Turkey); Aslanoglu, Mehmet, E-mail: maslanoglu@harran.edu.tr [Department of Chemistry, Harran University, Şanlıurfa 63510 (Turkey)

    2016-09-01

    An electrochemical sensor was prepared by modifying a glassy carbon electrode (GCE) with a composite of yttrium (III) oxide nanoparticles (Y{sub 2}O{sub 3}NPs) and carbon nanotubes (CNTs) for the determination of acetaminophen (ACT). Compared with a bare GCE and CNTs/GCE, the Y{sub 2}O{sub 3}NPs/CNTs/GCE exhibited a well-defined redox couple for ACT and highly enhanced the current response. The separations in the anodic and cathodic peak potentials (ΔE{sub p}) for ACT were 552 mV, 24 mV and 10 mV at ba4re GCE, CNTs/GCE and Y{sub 2}O{sub 3}NPs/CNTs/GCE, respectively. The observation of only 10 mV of ΔE{sub p} for ACT at Y{sub 2}O{sub 3}NPs/CNTs/GCE was a clear indication of a great acceleration of the electrode process compared to bare GCE and GCE modified with CNTs. Also, L-ascorbic acid (L-AA) and L-tyrosine (L-TRY) did not interfere with the selective determination of ACT. Square wave voltammetry (SWV) was performed for the quantification of ACT. A linear plot was obtained for current responses versus the concentrations of ACT over the range from 1.0 × 10{sup −10} to 1.8 × 10{sup −8} M with a detection limit of 3.0 × 10{sup −11} M (based on 3S{sub b}/m). The proposed composite material provided high electrocatalytic activity, improved voltammetric behavior, good selectivity and good reproducibility. The accurate quantification of ACT makes the proposed electrode of great interest for the public health. - Highlights: • A voltammetric sensor based on yttrium oxide was prepared for the detection of ACT. • The proposed electrode has greatly accelerated the voltammetric process of ACT. • A detection limit of 0.03 nM was obtained for ACT. • The proposed electrode exhibited great selectivity for ACT in the presence of L-AA and L-TRY. • The composite material exhibited high sensitivity, good stability and excellent reproducibility.

  13. Synthesis and evaluation of fluorine-18-labeled SA4503 as a selective sigma{sub 1} receptor ligand for positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Kazunori [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo 173-0022 (Japan) and Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Niigata 951-8585 (Japan)]. E-mail: kawamurak@bri.niigata-u.ac.jp; Tsukada, Hideo [Central Research Laboratory, Hamamatsu Photonics, K.K., Hamamatsu, Shizuoka 434-8601 (Japan); Shiba, Kazuhiro [Advanced Science Research Center, Kanazawa University, Kanazawa, Ishikawa 920-8640 (Japan); Tsuji, Chieko [NARD Institute, Ltd., Amagasaki, Hyogo 660-0805 (Japan); Harada, Norihiro [Central Research Laboratory, Hamamatsu Photonics, K.K., Hamamatsu, Shizuoka 434-8601 (Japan); Kimura, Yuichi [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo 173-0022 (Japan); Ishiwata, Kiichi [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo 173-0022 (Japan)

    2007-07-15

    The [{sup 18}F]fluoromethyl analog of the sigma{sub 1} selective ligand 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (SA4503) ([{sup 18}F]FM-SA4503) was prepared and its potential evaluated for the in vivo measurement of sigma{sub 1} receptors with positron emission tomography (PET). FM-SA4503 had selective affinity for the sigma{sub 1} receptor ( K {sub i} for sigma{sub 1} receptor, 6.4 nM; K {sub i} for sigma{sub 2} receptor, 250 nM) that was compatible with the affinity of SA4503 ( K {sub i} for sigma{sub 1} receptor, 4.4 nM; K {sub i} for sigma{sub 2} receptor, 242 nM). [{sup 18}F]FM-SA4503 was synthesized by {sup 18}F-fluoromethylation of O-demethyl SA4503 in the radiochemical yield of 2.9-16.6% at the end of bombardment with a specific activity of 37.8-283 TBq/mmol at the end of synthesis. In mice, the uptake of [{sup 18}F]FM-SA4503 in the brain was gradually increased for 30 min after injection, and then decreased. In the blocking study, brain uptake was significantly decreased by co-injection of haloperidol to 32% of control, and FM-SA4503 to 52% of control. In PET study of the monkey brain, high uptake was found in the cerebral cortex, thalamus and striatum. The radioactivity level of [{sup 18}F]FM-SA4503 in the brain regions gradually increased over a period of 120 min after injection, followed by a stable plateau phase until 180 min after injection. In pretreatment with haloperidol measurement of the monkey brain, the radioactivity level was 22-32% and 11-25% of the baseline at 60 and 180 min, respectively, after injection, suggesting high receptor-specific binding. [{sup 18}F]FM-SA4503 showed specific binding to sigma{sub 1} receptors in mice and monkeys; therefore, [{sup 18}F]FM-SA4503 has the potential for mapping sigma{sub 1} receptors in the brain.

  14. A sensitive and selective electrochemical biosensor for the determination of beta-amyloid oligomer by inhibiting the peptide-triggered in situ assembly of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Xing Y

    2017-04-01

    Full Text Available Yun Xing,1,2 Xiao-Zhen Feng,2 Lipeng Zhang,1 Jiating Hou,2 Guo-Cheng Han,2 Zhencheng Chen2 1Henan Province of Key Laboratory of New Optoelectronic Functional Materials, College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, 2School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin, Guangxi, People’s Republic of China Abstract: Soluble beta-amyloid (Aβ oligomer is believed to be the most important toxic species in the brain of Alzheimer’s disease (AD patients. Thus, it is critical to develop a simple method for the selective detection of Aβ oligomer with low cost and high sensitivity. In this paper, we report an electrochemical method for the detection of Aβ oligomer with a peptide as the bioreceptor and silver nanoparticle (AgNP aggregates as the redox reporters. This strategy is based on the conversion of AgNP-based colorimetric assay into electrochemical analysis. Specifically, the peptide immobilized on the electrode surface and presented in solution triggered together the in situ formation of AgNP aggregates, which produced a well-defined electrochemical signal. However, the specific binding of Aβ oligomer to the immobilized peptide prevented the in situ assembly of AgNPs. As a result, a poor electrochemical signal was observed. The detection limit of the method was found to be 6 pM. Furthermore, the amenability of this method for the analysis of Aβ oligomer in serum and artificial cerebrospinal fluid (aCSF samples was demonstrated. Keywords: electrochemical biosensors, Alzheimer’s disease, beta-amyloid oligomer, peptide, silver nanoparticles

  15. 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.

  16. 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.

  17. Morphology and Activity Tuning of Cu 3 Pt/C Ordered Intermetallic Nanoparticles by Selective Electrochemical Dealloying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Deli; Yu, Yingchao; Zhu, Jing; Liu, Sufen; Muller, David A.; Abruña, Héctor D.

    2015-02-11

    Improving the catalytic activity of Pt-based bimetallic nanoparticles is a key challenge in the application of proton-exchange membrane fuel cells. Electrochemical dealloying represents a powerful approach for tuning the surface structure and morphology of these catalyst nanoparticles. We present a comprehensive study of using electrochemical dealloying methods to control the morphology of ordered Cu3Pt/C intermetallic nanoparticles, which could dramatically affect their electrocatalytic activity for the oxygen reduction reaction (ORR). Depending on the electrochemical dealloying conditions, the nanoparticles with Pt-rich core–shell or porous structures were formed. We further demonstrate that the core–shell and porous morphologies can be combined to achieve the highest ORR activity. This strategy provides new guidelines for optimizing nanoparticles synthesis and improving electrocatalytic activity.

  18. 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.

  19. Laccase-catalyzed oxidation and intramolecular cyclization of dopamine: A new method for selective determination of dopamine with laccase/carbon nanotube-based electrochemical biosensors

    International Nuclear Information System (INIS)

    Xiang, Ling; Lin, Yuqing; Yu, Ping; Su, Lei; Mao, Lanqun

    2007-01-01

    This study demonstrates a new electrochemical method for the selective determination of dopamine (DA) with the coexistence of ascorbic acid (AA) and 3,4-dihydroxyphenylacetic acid (DOPAC) with laccase/multi-walled carbon nanotube (MWNT)-based biosensors prepared by cross-linking laccase into MWNT layer confined onto glassy carbon electrodes. The method described here is essentially based on the chemical reaction properties of DA including oxidation, intramolecular cyclization and disproportionation reactions to finally give 5,6-dihydroxyindoline quinone and on the uses of the two-electron and two-proton reduction of the formed 5,6-dihydroxyindoline quinone to constitute a method for the selective determination of DA at a negative potential that is totally separated from those for the redox processes of AA and DOPAC. Instead of the ECE reactions of DA with the first oxidation of DA being driven electrochemically, laccase is used here as the biocatalyst to drive the first oxidation of DA into its quinone form and thus initialize the sequential reactions of DA finally into 5,6-dihydroxyindoline quinone. In addition, laccase also catalyzes the oxidation of AA and DOPAC into electroinactive species with the concomitant reduction of O 2 . As a consequence, a combinational exploitation of the chemical properties inherent in DA and the multifunctional catalytic properties of laccase as well as the excellent electrochemical properties of carbon nanotubes substantially enables the prepared laccase/MWNT-based biosensors to be well competent for the selective determination of DA with the coexistence of physiological levels of AA and DOPAC. This demonstration offers a new method for the selective determination of DA, which could be potentially employed for the determination of DA in biological systems

  20. Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles

    International Nuclear Information System (INIS)

    Gholivand, Mohammad-Bagher; Jalalvand, Ali R.; Goicoechea, Hector C.

    2014-01-01

    For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1–30.0 μM and 30.0–330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. - Highlights: • Eight variables were screened by Min Run Res IV FD to identify the key variables. • Mathematical models for the two studied responses were developed by FCCCD. • By using DF the responses were optimized simultaneously. • The SEM image of the modified electrode was processed by digital image processing. • The sensor was successfully applied to determination of nitrite in real samples

  1. Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad-Bagher, E-mail: mbgholivand2013@gmail.com [Faculty of Chemistry, Razi University, Kermanshah 671496734 (Iran, Islamic Republic of); Jalalvand, Ali R. [Faculty of Chemistry, Razi University, Kermanshah 671496734 (Iran, Islamic Republic of); Laboratorio de Desarrollo Analítico y Quimiometría (LADAQ), Cátedra de Química Analítica I, Universidad Nacional del Litoral, Ciudad Universitaria, CC 242 (S3000ZAA), Santa Fe (Argentina); Goicoechea, Hector C. [Laboratorio de Desarrollo Analítico y Quimiometría (LADAQ), Cátedra de Química Analítica I, Universidad Nacional del Litoral, Ciudad Universitaria, CC 242 (S3000ZAA), Santa Fe (Argentina)

    2014-07-01

    For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1–30.0 μM and 30.0–330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. - Highlights: • Eight variables were screened by Min Run Res IV FD to identify the key variables. • Mathematical models for the two studied responses were developed by FCCCD. • By using DF the responses were optimized simultaneously. • The SEM image of the modified electrode was processed by digital image processing. • The sensor was successfully applied to determination of nitrite in real samples.

  2. A Nonoxidative Electrochemical Sensor Based on a Self-Doped Polyaniline/Carbon Nanotube Composite for Sensitive and Selective Detection of the Neurotransmitter Dopamine: A Review

    Directory of Open Access Journals (Sweden)

    Rishi R. Parajuli

    2008-12-01

    Full Text Available Most of the current techniques for in vivo detection of dopamine exploit the ease of oxidation of this compound. The major problem during the detection is the presence of a high concentration of ascorbic acid that is oxidized at nearly the same potential as dopamine on bare electrodes. Furthermore, the oxidation product of dopamine reacts with ascorbic acid present in samples and regenerates dopamine again, which severely limits the accuracy of the detection. Meanwhile, the product could also form a melanin-like insulating film on the electrode surface, which decreases the sensitivity of the electrode. Various surface modifications on the electrode, new materials for making the electrodes, and new electrochemical techniques have been exploited to solve these problems. Recently we developed a new electrochemical detection method that did not rely on direct oxidation of dopamine on electrodes, which may naturally solve these problems. This approach takes advantage of the high performance of our newly developed poly(anilineboronic acid/carbon nanotube composite and the excellent permselectivity of the ion-exchange polymer Nafion. The high affinity binding of dopamine to the boronic acid groups of the polymer affects the electrochemical properties of the polyaniline backbone, which act as the basis for the transduction mechanism of this non-oxidative dopamine sensor. The unique reduction capability and high conductivity of single-stranded DNA functionalized single-walled carbon nanotubes greatly improved the electrochemical activity of the polymer in a physiologically-relevant buffer, and the large surface area of the carbon nanotubes increased the density of the boronic acid receptors. The high sensitivity and selectivity of the sensor show excellent promise toward molecular diagnosis of Parkinson's disease. In this review, we will focus on the discussion of this novel detection approach, the new interferences in this detection approach, and how to

  3. Conducting electrospun fibres with polyanionic grafts as highly selective, label-free, electrochemical biosensor with a low detection limit for non-Hodgkin lymphoma gene.

    Science.gov (United States)

    Kerr-Phillips, Thomas E; Aydemir, Nihan; Chan, Eddie Wai Chi; Barker, David; Malmström, Jenny; Plesse, Cedric; Travas-Sejdic, Jadranka

    2018-02-15

    A highly selective, label-free sensor for the non-Hodgkin lymphoma gene, with an aM detection limit, utilizing electrochemical impedance spectroscopy (EIS) is presented. The sensor consists of a conducting electrospun fibre mat, surface-grafted with poly(acrylic acid) (PAA) brushes and a conducting polymer sensing element with covalently attached oligonucleotide probes. The sensor was fabricated from electrospun NBR rubber, embedded with poly(3,4-ethylenedioxythiophene) (PEDOT), followed by grafting poly(acrylic acid) brushes and then electrochemically polymerizing a conducting polymer monomer with ssDNA probe sequence pre-attached. The resulting non-Hodgkin lymphoma gene sensor showed a detection limit of 1aM (1 × 10 -18 mol/L), more than 400 folds lower compared to a thin-film analogue. The sensor presented extraordinary selectivity, with only 1%, 2.7% and 4.6% of the signal recorded for the fully non-complimentary, T-A and G-C base mismatch oligonucleotide sequences, respectively. We suggest that such greatly enhanced selectivity is due to the presence of negatively charged carboxylic acid moieties from PAA grafts that electrostatically repel the non-complementary and mismatch DNA sequences, overcoming the non-specific binding. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. 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

  5. A Chemically Synthesized Capture Agent Enables the Selective, Sensitive, and Robust Electrochemical Detection of Anthrax Protective Antigen

    Science.gov (United States)

    2014-08-01

    Electrochemical Oxidation of Catechol and Para - Aminophenol Esters in the Presence of Hydrolases. Bioelectrochem. Bioenerg. 1980, 7, 11–24. 26. Evans-Nguyen, K. M...platform. Analytical HPLC (a) and MALDI-TOF (b) traces of biligand capture agentwithno thermal treatment, and after 5 days of storage as a powder at...sample of biligand was stored for 5 days at 65 C under nitrogen atmosphere. Analy- tical HPLC traces (Figure 4a) andMALDI-TOF (Figure 4b) reveal

  6. Ion-Exchange Membranes Based on Polynorbornenes with Fluorinated Imide Side Chain Groups

    Directory of Open Access Journals (Sweden)

    Arlette A. Santiago

    2012-01-01

    Full Text Available The electrochemical characteristics of cation-exchange membranes based on polynorbornenes with fluorinated and sulfonated dicarboximide side chain groups were reported. This study was extended to a block copolymer containing structural units with phenyl and 4-oxybenzenesulfonic acid, 2,3,5,6-tetrafluorophenyl moieties replacing the hydrogen atom of the dicarboximide group. A thorough study on the electrochemical characteristics of the membranes involving electromotive forces of concentration cells and proton conductivity is reported. The proton permselectivity of the membranes is also discussed.

  7. Preparation and evaluation of a novel molecularly imprinted polymer coating for selective extraction of indomethacin from biological samples by electrochemically controlled in-tube solid phase microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Asiabi, Hamid [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Yamini, Yadollah, E-mail: yyamini@modares.ac.ir [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Seidi, Shahram; Ghahramanifard, Fazel [Department of Analytical Chemistry, Faculty of Chemistry, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of)

    2016-03-24

    In the present work, an automated on-line electrochemically controlled in-tube solid-phase microextraction (EC-in-tube SPME) coupled with HPLC-UV was developed for the selective extraction and preconcentration of indomethacin as a model analyte in biological samples. Applying an electrical potential can improve the extraction efficiency and provide more convenient manipulation of different properties of the extraction system including selectivity, clean-up, rate, and efficiency. For more enhancement of the selectivity and applicability of this method, a novel molecularly imprinted polymer coated tube was prepared and applied for extraction of indomethacin. For this purpose, nanostructured copolymer coating consisting of polypyrrole doped with ethylene glycol dimethacrylate was prepared on the inner surface of a stainless-steel tube by electrochemical synthesis. The characteristics and application of the tubes were investigated. Electron microscopy provided a cross linked porous surface and the average thickness of the MIP coating was 45 μm. Compared with the non-imprinted polymer coated tubes, the special selectivity for indomethacin was discovered with the molecularly imprinted coated tube. Moreover, stable and reproducible responses were obtained without being considerably influenced by interferences commonly existing in biological samples. Under the optimal conditions, the limits of detection were in the range of 0.07–2.0 μg L{sup −1} in different matrices. This method showed good linearity for indomethacin in the range of 0.1–200 μg L{sup −1}, with coefficients of determination better than 0.996. The inter- and intra-assay precisions (RSD%, n = 3) were respectively in the range of 3.5–8.4% and 2.3–7.6% at three concentration levels of 7, 70 and 150 μg L{sup −1}. The results showed that the proposed method can be successfully applied for selective analysis of indomethacin in biological samples. - Graphical abstract: An automated on

  8. 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.

  9. 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.

  10. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

    Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

  11. Spontaneous and Selective Nanowelding of Silver Nanowires by Electrochemical Ostwald Ripening and High Electrostatic Potential at the Junctions for High-Performance Stretchable Transparent Electrodes.

    Science.gov (United States)

    Lee, Hyo-Ju; Oh, Semi; Cho, Ki-Yeop; Jeong, Woo-Lim; Lee, Dong-Seon; Park, Seong-Ju

    2018-04-25

    Metal nanowires have been gaining increasing attention as the most promising stretchable transparent electrodes for emerging field of stretchable optoelectronic devices. Nanowelding technology is a major challenge in the fabrication of metal nanowire networks because the optoelectronic performances of metal nanowire networks are mostly limited by the high junction resistance between nanowires. We demonstrate the spontaneous and selective welding of Ag nanowires (AgNWs) by Ag solders via an electrochemical Ostwald ripening process and high electrostatic potential at the junctions of AgNWs. The AgNWs were welded by depositing Ag nanoparticles (AgNPs) on the conducting substrate and then exposing them to water at room temperature. The AgNPs were spontaneously dissolved in water to form Ag + ions, which were then reduced to single-crystal Ag solders selectively at the junctions of the AgNWs. Hence, the welded AgNWs showed higher optoelectronic and stretchable performance compared to that of as-formed AgNWs. These results indicate that electrochemical Ostwald ripening-based welding can be used as a promising method for high-performance metal nanowire electrodes in various next-generation devices such as stretchable solar cells, stretchable displays, organic light-emitting diodes, and skin sensors.

  12. [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.

  13. 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.

  14. Solubility-Parameter-Guided Solvent Selection to Initiate Ostwald Ripening for Interior Space-Tunable Structures with Architecture-Dependent Electrochemical Performance.

    Science.gov (United States)

    Mao, Baoguang; Guo, Donglei; Qin, Jinwen; Meng, Tao; Wang, Xin; Cao, Minhua

    2018-01-08

    Despite significant advancement in preparing various hollow structures by Ostwald ripening, one common problem is the intractable uncontrollability of initiating Ostwald ripening due to the complexity of the reaction processes. Here, a new strategy on Hansen solubility parameter (HSP)-guided solvent selection to initiate Ostwald ripening is proposed. Based on this comprehensive principle for solvent optimization, N,N-dimethylformamide (DMF) was screened out, achieving accurate synthesis of interior space-tunable MoSe 2 spherical structures (solid, core-shell, yolk-shell and hollow spheres). The resultant MoSe 2 structures exhibit architecture-dependent electrochemical performances towards hydrogen evolution reaction and sodium-ion batteries. This pre-solvent selection strategy can effectively provide researchers great possibility in efficiently synthesizing various hollow structures. This work paves a new pathway for deeply understanding Ostwald ripening. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. 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.

  16. 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 ...

  17. 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

  18. Fabrication and characterization of a nanometer-sized optical fiber electrode based on selective chemical etching for scanning electrochemical/optical microscopy.

    Science.gov (United States)

    Maruyama, Kenichi; Ohkawa, Hiroyuki; Ogawa, Sho; Ueda, Akio; Niwa, Osamu; Suzuki, Koji

    2006-03-15

    We have already reported a method for fabricating ultramicroelectrodes (Suzuki, K. JP Patent, 2004-45394, 2004). This method is based on the selective chemical etching of optical fibers. In this work, we undertake a detailed investigation involving a combination of etched optical fibers with various types of tapered tip (protruding-shape, double- (or pencil-) shape and triple-tapered electrode) and insulation with electrophoretic paint. Our goal is to establish a method for fabricating nanometer-sized optical fiber electrodes with high reproducibility. As a result, we realized pencil-shaped and triple-tapered electrodes that had radii in the nanometer range with high reproducibility. These nanometer-sized electrodes showed well-defined sigmoidal curves and stable diffusion-limited responses with cyclic voltammetry. The pencil-shaped optical fiber, which has a conical tip with a cone angle of 20 degrees , was effective for controlling the electrode radius. The pencil-shaped electrodes had higher reproducibility and smaller electrode radii (r(app) etched optical fiber electrodes. By using a pencil-shaped electrode with a 105-nm radius as a probe, we obtained simultaneous electrochemical and optical images of an implantable interdigitated array electrode. We achieved nanometer-scale resolution with a combination of scanning electrochemical microscopy SECM and optical microscopy. The resolution of the electrochemical and optical images indicated sizes of 300 and 930 nm, respectively. The neurites of living PC12 cells were also successfully imaged on a 1.6-microm scale by using the negative feedback mode of an SECM.

  19. Determination of organic fluorine in aqueous samples with neutron activation analysis in comparison with the DIN method

    Energy Technology Data Exchange (ETDEWEB)

    Rollinger, D. [Institut fuer Kernchemie, Universitaet Mainz, Fritz-Strassmann-Weg 2, D-55099 Mainz (Germany); Kratz, K.L. [Institut fuer Kernchemie, Universitaet Mainz, Fritz-Strassmann-Weg 2, D-55099 Mainz (Germany)

    1996-04-01

    Neutron activation analysis (NAA) has been used as detection technique for adsorbable organic fluorine in aqueous samples. The results have been compared with the standardized DIN method which uses a fluoride-ion-selective electrode (ISE). (orig.). With 3 tabs.

  20. Low molecular weight salts combined with fluorinated solvents for electrolytes

    Science.gov (United States)

    Tikhonov, Konstantin; Yip, Ka Ki; Lin, Tzu-Yuan; Lei, Norman; Guerrero-Zavala, Guillermo; Kwong, Kristie W.

    2015-11-10

    Provided are electrochemical cells and electrolytes used to build such cells. An electrolyte includes at least one salt having a molecular weight less than about 250. Such salts allow forming electrolytes with higher salt concentrations and ensure high conductivity and ion transport in these electrolytes. The low molecular weight salt may have a concentration of at least about 0.5M and may be combined with one or more other salts, such as linear and cyclic imide salts and/or methide salts. The concentration of these additional salts may be less than that of the low molecular weight salt, in some embodiments, twice less. The additional salts may have a molecular weight greater than about 250. The electrolyte may also include one or more fluorinated solvents and may be capable of maintaining single phase solutions at between about -30.degree. C. to about 80.degree. C.

  1. 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)

  2. Sonochemical and sustainable synthesis of graphene-gold (G-Au) nanocomposites for enzymeless and selective electrochemical detection of nitric oxide.

    Science.gov (United States)

    Geetha Bai, Renu; Muthoosamy, Kasturi; Zhou, Meifang; Ashokkumar, Muthupandian; Huang, Nay Ming; Manickam, Sivakumar

    2017-01-15

    In this study, a sonochemical approach was utilised for the development of graphene-gold (G-Au) nanocomposite. Through the sonochemical method, simultaneous exfoliation of graphite and the reduction of gold chloride occurs to produce highly crystalline G-Au nanocomposite. The in situ growth of gold nanoparticles (AuNPs) took place on the surface of exfoliated few-layer graphene sheets. The G-Au nanocomposite was characterised by UV-vis, XRD, FTIR, TEM, XPS and Raman spectroscopy techniques. This G-Au nanocomposite was used to modify glassy carbon electrode (GCE) to fabricate an electrochemical sensor for the selective detection of nitric oxide (NO), a critical cancer biomarker. G-Au modified GCE exhibited an enhanced electrocatalytic response towards the oxidation of NO as compared to other control electrodes. The electrochemical detection of NO was investigated by linear sweep voltammetry analysis, utilising the G-Au modified GCE in a linear range of 10-5000μM which exhibited a limit of detection of 0.04μM (S/N=3). Furthermore, this enzyme-free G-Au/GCE exhibited an excellent selectivity towards NO in the presence of interferences. The synergistic effect of graphene and AuNPs, which facilitated exceptional electron-transfer processes between the electrolyte and the GCE thereby improving the sensing performance of the fabricated G-Au modified electrode with stable and reproducible responses. This G-Au nanocomposite introduces a new electrode material in the sensitive and selective detection of NO, a prominent biomarker of cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Electrochemical photovoltaic cells and electrodes

    Science.gov (United States)

    Skotheim, Terje A.

    1984-01-01

    Improved electrochemical photovoltaic cells and electrodes for use therein, particularly electrodes employing amorphous silicon or polyacetylene coating are produced by a process which includes filling pinholes or porous openings in the coatings by electrochemical oxidation of selected monomers to deposit insulating polymer in the openings.

  4. Electrochemical Sensors for Clinic Analysis

    Directory of Open Access Journals (Sweden)

    Guang Li

    2008-03-01

    Full Text Available Demanded by modern medical diagnosis, advances in microfabrication technology have led to the development of fast, sensitive and selective electrochemical sensors for clinic analysis. This review addresses the principles behind electrochemical sensor design and fabrication, and introduces recent progress in the application of electrochemical sensors to analysis of clinical chemicals such as blood gases, electrolytes, metabolites, DNA and antibodies, including basic and applied research. Miniaturized commercial electrochemical biosensors will form the basis of inexpensive and easy to use devices for acquiring chemical information to bring sophisticated analytical capabilities to the non-specialist and general public alike in the future.

  5. Electrochemical Selective and Simultaneous Detection of Diclofenac and Ibuprofen in Aqueous Solution Using HKUST-1 Metal-Organic Framework-Carbon Nanofiber Composite Electrode

    Directory of Open Access Journals (Sweden)

    Sorina Motoc

    2016-10-01

    Full Text Available In this study, the detection protocols for the individual, selective, and simultaneous determination of ibuprofen (IBP and diclofenac (DCF in aqueous solutions have been developed using HKUST-1 metal-organic framework-carbon nanofiber composite (HKUST-CNF electrode. The morphological and electrical characterization of modified composite electrode prepared by film casting was studied by scanning electronic microscopy and four-point-probe methods. The electrochemical characterization of the electrode by cyclic voltammetry (CV was considered the reference basis for the optimization of the operating conditions for chronoamperometry (CA and multiple-pulsed amperometry (MPA. This electrode exhibited the possibility to selectively detect IBP and DCF by simple switching the detection potential using CA. However, the MPA operated under optimum working conditions of four potential levels selected based on CV shape in relation to the potential value, pulse time, and potential level number, and order allowed the selective/simultaneous detection of IBP and DCF characterized by the enhanced detection performance. For this application, the HKUST-CNF electrode exhibited a good stability and reproducibility of the results was achieved.

  6. Electrochemical Selective and Simultaneous Detection of Diclofenac and Ibuprofen in Aqueous Solution Using HKUST-1 Metal-Organic Framework-Carbon Nanofiber Composite Electrode.

    Science.gov (United States)

    Motoc, Sorina; Manea, Florica; Iacob, Adriana; Martinez-Joaristi, Alberto; Gascon, Jorge; Pop, Aniela; Schoonman, Joop

    2016-10-17

    In this study, the detection protocols for the individual, selective, and simultaneous determination of ibuprofen (IBP) and diclofenac (DCF) in aqueous solutions have been developed using HKUST-1 metal-organic framework-carbon nanofiber composite (HKUST-CNF) electrode. The morphological and electrical characterization of modified composite electrode prepared by film casting was studied by scanning electronic microscopy and four-point-probe methods. The electrochemical characterization of the electrode by cyclic voltammetry (CV) was considered the reference basis for the optimization of the operating conditions for chronoamperometry (CA) and multiple-pulsed amperometry (MPA). This electrode exhibited the possibility to selectively detect IBP and DCF by simple switching the detection potential using CA. However, the MPA operated under optimum working conditions of four potential levels selected based on CV shape in relation to the potential value, pulse time, and potential level number, and order allowed the selective/simultaneous detection of IBP and DCF characterized by the enhanced detection performance. For this application, the HKUST-CNF electrode exhibited a good stability and reproducibility of the results was achieved.

  7. 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.

  8. Electrochemical biosensors

    CERN Document Server

    Cosnier, Serge

    2015-01-01

    "This is an excellent book on modern electrochemical biosensors, edited by Professor Cosnier and written by leading international experts. It covers state-of-the-art topics of this important field in a clear and timely manner."-Prof. Joseph Wang, UC San Diego, USA  "This book covers, in 13 well-illustrated chapters, the potential of electrochemical methods intimately combined with a biological component for the assay of various analytes of biological and environmental interest. Particular attention is devoted to the description of electrochemical microtools in close contact with a biological cell for exocytosis monitoring and to the use of nanomaterials in the electrochemical biosensor architecture for signal improvement. Interestingly, one chapter describes the concept and design of self-powered biosensors derived from biofuel cells. Each topic is reviewed by experts very active in the field. This timely book is well suited for providing a good overview of current research trends devoted to electrochemical...

  9. 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

  10. 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

  11. Synthesis of Regiospecifically Fluorinated Conjugated Dienamides

    Directory of Open Access Journals (Sweden)

    Mohammad Chowdhury

    2014-04-01

    Full Text Available Modular synthesis of regiospecifically fluorinated 2,4-diene Weinreb amides, with defined stereochemistry at both double bonds, was achieved via two sequential Julia-Kocienski olefinations. In the first step, a Z-a-fluorovinyl Weinreb amide unit with a benzothiazolylsulfanyl substituent at the allylic position was assembled. This was achieved via condensation of two primary building blocks, namely 2-(benzo[d]thiazol-2-ylsulfonyl-2-fluoro-N-methoxy-N-methylacetamide (a Julia-Kocienski olefination reagent and 2-(benzo[d]thiazol-2-ylthioacetaldehyde (a bifunctional building block. This condensation was highly Z-selective and proceeded in a good 76% yield. Oxidation of benzothiazolylsulfanyl moiety furnished a second-generation Julia-Kocienski olefination reagent, which was used for the introduction of the second olefinic linkage via DBU-mediated condensations with aldehydes, to give (2Z,4E/Z-dienamides in 50%–74% yield. Although olefinations were 4Z-selective, (2Z,4E/Z-2-fluoro-2,4-dienamides could be readily isomerized to the corresponding 5-substituted (2Z,4E-2-fluoro-N-methoxy-N-methylpenta-2,4-dienamides in the presence of catalytic iodine.

  12. Fluorinated Phenylalanine Precursor Resistance in Yeast

    Directory of Open Access Journals (Sweden)

    Ian S. Murdoch

    2018-06-01

    Full Text Available Development of a counter-selection method for phenylalanine auxotrophy could be a useful tool in the repertoire of yeast genetics. Fluorinated and sulfurated precursors of phenylalanine were tested for toxicity in Saccharomyces cerevisiae. One such precursor, 4-fluorophenylpyruvate (FPP, was found to be toxic to several strains from the Saccharomyces and Candida genera. Toxicity was partially dependent on ARO8 and ARO9, and correlated with a strain’s ability to convert FPP into 4-fluorophenylalanine (FPA. Thus, strains with deletions in ARO8 and ARO9, having a mild phenylalanine auxotrophy, could be separated from a culture of wild-type strains using FPP. Tetrad analysis suggests FPP resistance in one strain is due to two genes. Strains resistant to FPA have previously been shown to exhibit increased phenylethanol production. However, FPP resistant isolates did not follow this trend. These results suggest that FPP could effectively be used for counter-selection but not for enhanced phenylethanol production.

  13. Synthesis of Regiospecifically Fluorinated Conjugated Dienamides

    Science.gov (United States)

    Chowdhury, Mohammad; Mandal, Samir K.; Banerjee, Shaibal; Zajc, Barbara

    2015-01-01

    Modular synthesis of regiospecifically fluorinated 2,4-diene Weinreb amides, with defined stereochemistry at both double bonds, was achieved via two sequential Julia-Kocienski olefinations. In the first step, a Z-α-fluorovinyl Weinreb amide unit with a benzothiazolylsulfanyl substituent at the allylic position was assembled. This was achieved via condensation of two primary building blocks, namely 2-(benzo[d]thiazol-2-ylsulfonyl)-2-fluoro-N-methoxy-N-methylacetamide (a Julia-Kocienski olefination reagent) and 2-(benzo[d]thiazol-2-ylthio)acetaldehyde (a bifunctional building block). This condensation was highly Z-selective and proceeded in a good 76% yield. Oxidation of benzothiazolylsulfanyl moiety furnished a second-generation Julia-Kocienski olefination reagent, which was used for the introduction of the second olefinic linkage via DBU-mediated condensations with aldehydes, to give (2Z,4E/Z)-dienamides in 50%–74% yield. Although olefinations were 4Z-selective, (2Z,4E/Z)-2-fluoro-2,4-dienamides could be readily isomerized to the corresponding 5-substituted (2Z,4E)-2-fluoro-N-methoxy-N-methylpenta-2,4-dienamides in the presence of catalytic iodine. PMID:24727415

  14. 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.

  15. 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.

  16. 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

  17. Tape casting fluorinated YBC123

    International Nuclear Information System (INIS)

    Taylor, J.A.T.; Luke, D.M.; Whiteley, B.A.

    1991-01-01

    Tape casting the superconducting Ba-Y-Cu oxide was accomplished by several laboratories and show promise for being a versatile forming technique. The major problem is low current density, probably due to lack of grain alignment and grain boundary related weak links. The latter problem may be due to formation of carbonates and hydroxides during binder burnout. Preliminary work done at Alfred shows that a bimodal powder size distribution displays significant alignment after tape casting and that F treated powder is resistant to attack by steam at 100C. Such corrosion resistant powder cast as form tape should survive the binder burnout without the detrimental grain boundary phases that develop from reaction of the superconducting phase, steam and carbon dioxide. This paper presents the results of an investigation of tape casting fluorinated powder with a bimodal size distribution

  18. (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

  19. Electrochemical kinetics and X-ray absorption spectroscopy investigations of select chalcogenide electrocatalysts for oxygen reduction reaction applications

    International Nuclear Information System (INIS)

    Ziegelbauer, Joseph M.; Murthi, Vivek S.; O'Laoire, Cormac; Gulla, Andrea F.; Mukerjee, Sanjeev

    2008-01-01

    Transition metal-based chalcogenide electrocatalysts exhibit a promising level of performance for oxygen reduction reaction applications while offering significant economic benefits over the state of the art Pt/C systems. The most active materials are based on Ru x Se y clusters, but the toxicity of selenium will most likely limit their embrace by the marketplace. Sulfur-based analogues do not suffer from toxicity issues, but suffer from substantially less activity and stability than their selenium brethren. The structure/property relationships that result in these properties are not understood due to ambiguities regarding the specific morphologies of Ru x S y -based chalcogenides. To clarify these properties, an electrochemical kinetics study was interpreted in light of extensive X-ray diffraction, scanning electron microscopy, and in situ X-ray absorption spectroscopy evaluations. The performance characteristics of ternary M x Ru y S z /C (M = Mo, Rh, or Re) chalcogenide electrocatalysts synthesized by the now-standard low-temperature nonaqueous (NA) route are compared to commercially available (De Nora) Rh- and Ru-based systems. Interpretation of performance differences is made in regards to bulk and surface properties of these systems. In particular, the overall trends of the measured activation energies in respect to increasing overpotential and the gross energy values can be explained in regards to these differences

  20. Label-free electrochemical aptasensor constructed by layer-by-layer technology for sensitive and selective detection of cancer cells.

    Science.gov (United States)

    Wang, Tianshu; Liu, Jiyang; Gu, Xiaoxiao; Li, Dan; Wang, Jin; Wang, Erkang

    2015-07-02

    Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 10(6) cells/mL with a detection limit as low as 10 cells/mL for the detection of cancer cells. Copyright © 2015. Published by Elsevier B.V.

  1. Extraction of lithium from neutral salt solutions with fluorinated β-diketones

    International Nuclear Information System (INIS)

    Seeley, F.G.; Baldwin, W.H.

    1976-01-01

    Lithium was selectively extracted from near-neutral aqueous solutions of alkali metal salts. The mechanism by which this was achieved involves the formation of the trioctylphosphine oxide adduct of a lithium chelate of a fluorinated β-diketone, which is then readily extractable into an organic diluent. High separation factors were obtained from sodium, potassium, rubidium, and cesium. The selectivity of the fluorinated β-diketones for lithium over the alkaline earths was found to be poor. A suggested general flowsheet for the recovery of lithium from a salt brine concentrate is included. (author)

  2. Extraction of lithium from neutral salt solutions with fluorinated. beta. -diketones

    Energy Technology Data Exchange (ETDEWEB)

    Seeley, F.G.; Baldwin, W.H.

    1976-01-01

    Lithium was selectively extracted from near-neutral aqueous solutions of alkali metal salts. The mechanism by which this was achieved involves the formation of the trioctylphosphine oxide adduct of a lithium chelate of a fluorinated ..beta..-diketone, which is then readily extractable into an organic diluent. High separation factors were obtained from sodium, potassium, rubidium, and cesium. The selectivity of the fluorinated ..beta..-diketones for lithium over the alkaline earths was found to be poor. A suggested general flowsheet for the recovery of lithium from a salt brine concentrate is included.

  3. 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.

  4. 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

  5. Electrochemical ion separation in molten salts

    Science.gov (United States)

    Spoerke, Erik David; Ihlefeld, Jon; Waldrip, Karen; Wheeler, Jill S.; Brown-Shaklee, Harlan James; Small, Leo J.; Wheeler, David R.

    2017-12-19

    A purification method that uses ion-selective ceramics to electrochemically filter waste products from a molten salt. The electrochemical method uses ion-conducting ceramics that are selective for the molten salt cations desired in the final purified melt, and selective against any contaminant ions. The method can be integrated into a slightly modified version of the electrochemical framework currently used in pyroprocessing of nuclear wastes.

  6. 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

  7. 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.

  8. Label-free electrochemical aptasensor constructed by layer-by-layer technology for sensitive and selective detection of cancer cells

    International Nuclear Information System (INIS)

    Wang, Tianshu; Liu, Jiyang; Gu, Xiaoxiao; Li, Dan; Wang, Jin; Wang, Erkang

    2015-01-01

    Highlights: • Fc-PAH was modified on the surface of graphene to prepare hybid nanocomposite (Fc-PAH-G). • A cytosensor was constructed with Fc-PAH-G, PSS and aptamer AS1411 by LBL technology. • The sensing interface introduced more redox probe and enhanced current signal on electrode. • The sensor showed a detection range of 10–10 6 cells/mL with a detection limit of 10 cells/mL. - Abstract: Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 10 6 cells/mL with a detection limit as low as 10 cells/mL for the detection of cancer cells

  9. Label-free electrochemical aptasensor constructed by layer-by-layer technology for sensitive and selective detection of cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tianshu [College of Physics, Jilin University, Changchun, Jilin 130012 (China); State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Liu, Jiyang; Gu, Xiaoxiao; Li, Dan [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Wang, Jin, E-mail: jin.wang.1@stonybrook.edu [College of Physics, Jilin University, Changchun, Jilin 130012 (China); State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Department of Chemistry, Physics and Applied Mathematics, State University of New York at Stony Brook, Stony Brook, NY 11794-3400 (United States); Wang, Erkang, E-mail: ekwang@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China)

    2015-07-02

    Highlights: • Fc-PAH was modified on the surface of graphene to prepare hybid nanocomposite (Fc-PAH-G). • A cytosensor was constructed with Fc-PAH-G, PSS and aptamer AS1411 by LBL technology. • The sensing interface introduced more redox probe and enhanced current signal on electrode. • The sensor showed a detection range of 10–10{sup 6} cells/mL with a detection limit of 10 cells/mL. - Abstract: Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 10{sup 6} cells/mL with a detection limit as low as 10 cells/mL for the detection of cancer cells.

  10. Electrochemical Processes

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers

    1997-01-01

    The notes describe in detail primary and secondary galvanic cells, fuel cells, electrochemical synthesis and electroplating processes, corrosion: measurments, inhibitors, cathodic and anodic protection, details of metal dissolution reactions, Pourbaix diagrams and purification of waste water from...

  11. Electrochemical analysis

    International Nuclear Information System (INIS)

    Hwang, Hun

    2007-02-01

    This book explains potentiometry, voltametry, amperometry and basic conception of conductometry with eleven chapters. It gives the specific descriptions on electrochemical cell and its mode, basic conception of electrochemical analysis on oxidation-reduction reaction, standard electrode potential, formal potential, faradaic current and faradaic process, mass transfer and overvoltage, potentiometry and indirect potentiometry, polarography with TAST, normal pulse and deferential pulse, voltammetry, conductometry and conductometric titration.

  12. On the selection of the anode material for the electrochemical removal of methylparaben from different aqueous media

    International Nuclear Information System (INIS)

    Steter, Juliana R.; Brillas, Enric; Sirés, Ignasi

    2016-01-01

    Highlights: • Comparative performance of EO-H 2 O 2 , EF and PEF with BDD, Pt and DSA as anodes. • Poor effect of anode on methylparaben mineralization by PEF but large effect in EO-H 2 O 2 . • Pseudo-first-order decay kinetics in EO-H 2 O 2 and much quicker complex kinetics in PEF. • Beneficial effect of Cl − in EO-H 2 O 2 but slightly or significantly detrimental in EF and PEF. • Quickest degradation in PEF with BDD, yielding chlorinated and non-chlorinated by-products. - Abstract: Parabens are widely used industrial preservatives, routinely found in wastewater along with major inorganic ions like sulfate and chloride. This work investigates the oxidation ability of three electrochemical processes in tank reactors equipped with an air-diffusion cathode to electrogenerate H 2 O 2 on site, namely electro-oxidation (EO-H 2 O 2 ), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF), to degrade aqueous solutions of methylparaben (MeP) at pH 3.0. Their performance using boron-doped diamond (BDD), Pt or two kinds of dimensionally stable anodes (DSA ® ) has been compared from the analysis of mineralization profiles and decay kinetics in the presence of sulfate and/or chloride ions. The use of BDD ensured the overall mineralization in all three processes according to the sequence: PEF > EF > EO-H 2 O 2 , thanks to the contribution of BDD(·OH), ·OH and UVA light. Pt and DSA ® became an interesting alternative in PEF, with slower organic matter removal but similar final mineralization percentages, being much less powerful than BDD in EO-H 2 O 2 . The presence of Cl − was beneficial in the latter process, due to the formation of active chlorine as an additional oxidant that caused a much faster decay of MeP. Conversely, it became significantly detrimental in EF due to the partial destruction of H 2 O 2 and ·OH in the bulk by active chlorine and Cl − , respectively. The oxidation power of PEF was so high that similar fast, complex decay kinetics was

  13. A highly selective electrochemical sensor based on molecularly imprinted polypyrrole-modified gold electrode for the determination of glyphosate in cucumber and tap water.

    Science.gov (United States)

    Zhang, Chao; She, Yongxin; Li, Tengfei; Zhao, Fengnian; Jin, Maojun; Guo, Yirong; Zheng, Lufei; Wang, Shanshan; Jin, Fen; Shao, Hua; Liu, Haijin; Wang, Jing

    2017-12-01

    An electrochemical sensor based on molecularly imprinted polypyrrole (MIPPy) was developed for selective and sensitive detection of the herbicide glyphosate (Gly) in cucumber and tap water samples. The sensor was prepared via synthesis of molecularly imprinted polymers on a gold electrode in the presence of Gly as the template molecule and pyrrole as the functional monomer by cyclic voltammetry (CV). The sensor preparation conditions including the ratio of template to functional monomers, number of CV cycles in the electropolymerization process, the method of template removal, incubation time, and pH were optimized. Under the optimal experimental conditions, the DPV peak currents of hexacyanoferrate/hexacyanoferrite changed linearly with Gly concentration in the range from 5 to 800 ng mL -1 , with a detection limit of 0.27 ng mL -1 (S/N = 3). The sensor was used to detect the concentration of Gly in cucumber and tap water samples, with recoveries ranging from 72.70 to 98.96%. The proposed sensor showed excellent selectivity, good stability and reversibility, and could detect the Gly in real samples rapidly and sensitively. Graphical abstract Schematic illustration of the experimental procedure to detect Gly using the MIPPy electrode.

  14. Conjugated Polymers Containing BODIPY and Fluorene Units for Sensitive Detection of CN− Ions: Site-Selective Synthesis, Photo-Physical and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Tian He

    2017-10-01

    Full Text Available Conjugated polymers containing distinct molecular units are expected to be very interesting because of their unique properties endowed by these units and the formed conjugated polymers. Herein, four new conjugated copolymers based on fluorene and 4,4’-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY have been designed and synthesized via Sonogashira polymerization. The fluorene unit was attached to the 3,5- or 2,6-positions of BODIPY by ethynylenes or p-diacetylenebenzene. The obtained polymers show good thermal stability and broad absorption in the wavelength range from 300 to 750 nm. The effects of site-selective copolymerization and conjugation length along the polymer backbone on the optoelectronic and electrochemical properties of these copolymers were systematically studied by UV-Vis spectroscopy, photoluminescence (PL and cyclic voltammetry. Besides, it is found that the BODIPY-based copolymers exhibit selectively sensitive responses to cyanide anions, resulting in obvious change of UV-Vis absorption spectra and significant fluorescence quenching of the polymers among various common anions.

  15. 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.)

  16. 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...

  17. Electrochemical reduction of NOx

    DEFF Research Database (Denmark)

    Traulsen, Marie Lund

    NO and NO2 (collectively referred to as NOx) are air pollutants, and the largest single contributor to NOx pollution is automotive exhaust. This study investigates electrochemical deNOx, a technology which aims to remove NOx from automotive diesel exhaust by electrochemical reduction of NOx to N2...... and O2. The focus in this study is on improving the activity and selectivity of solid oxide electrodes for electrochemical deNOx by addition of NOx storage compounds to the electrodes. Two different composite electrodes, La0.85Sr0.15MnO3-δ-Ce0.9Gd0.1O1.95 (LSM15-CGO10) and La0.85Sr0.15FeO3-δ-Ce0.9Gd0.1O......1.95 (LSF15-CGO10), have been investigated in combination with three different NOx storage compounds: BaO, K2O and MnOx. The main focus in the investigation has been on conversion measurements and electrochemical characterization, the latter by means of electrochemical impedance spectroscopy...

  18. 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.

  19. The selective electrochemical detection of homocysteine in the presence of glutathione, cysteine, and ascorbic acid using carbon electrodes.

    Science.gov (United States)

    Lee, P T; Lowinsohn, D; Compton, R G

    2014-08-07

    The detection of homocysteine, HCys, was achieved with the use of catechol via 1,4-Michael addition reaction using carbon electrodes: a glassy carbon electrode and a carbon nanotube modified glassy carbon electrode. The selective detection of homocysteine was investigated and achieved in the absence and presence of glutathione, cysteine and ascorbic acid using cyclic voltammetry and square wave voltammetry. A calibration curve of homocysteine detection was determined and the sensitivity is (0.20 ± 0.02) μA μM(-1) and the limit of detection is 660 nM within the linear range. Lastly, commercially available multi walled carbon nanotube screen printed electrodes were applied to the system for selective homocysteine detection. This work presents a potential practical application towards medical applications as it can be highly beneficial towards quality healthcare management.

  20. Electrochemical biosensors for hormone analyses.

    Science.gov (United States)

    Bahadır, Elif Burcu; Sezgintürk, Mustafa Kemal

    2015-06-15

    Electrochemical biosensors have a unique place in determination of hormones due to simplicity, sensitivity, portability and ease of operation. Unlike chromatographic techniques, electrochemical techniques used do not require pre-treatment. Electrochemical biosensors are based on amperometric, potentiometric, impedimetric, and conductometric principle. Amperometric technique is a commonly used one. Although electrochemical biosensors offer a great selectivity and sensitivity for early clinical analysis, the poor reproducible results, difficult regeneration steps remain primary challenges to the commercialization of these biosensors. This review summarizes electrochemical (amperometric, potentiometric, impedimetric and conductometric) biosensors for hormone detection for the first time in the literature. After a brief description of the hormones, the immobilization steps and analytical performance of these biosensors are summarized. Linear ranges, LODs, reproducibilities, regenerations of developed biosensors are compared. Future outlooks in this area are also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. 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.

  2. Fundamental electrochemiluminescence characteristics of fluorine-doped tin oxides synthesized by sol-gel combustion.

    Science.gov (United States)

    Moon, B H; Chaoumead, A; Sung, Y M

    2013-10-01

    Fluorine-doped tin oxide (FTO) materials synthesized by sol-gel combustion method were investigated for electrochemical luminescence (ECL) application. Effects of sol-gel combustion conditions on the structures and morphology of the porous FTO (p-FTO) materials were studied. ECL efficiency of p-FTO-based cell was about 251 cd/m2 at 4 V bias, which is higher than the sell using only FTO electrodes (102.8 cd/m2). The highest intensity of the emitting light was obtained at the wavelength of about 610 nm. The porous FTO layer was effective for increasing ECL intensities.

  3. 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 ...

  4. 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.

  5. 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.)

  6. 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.

  7. Electrochemical evidences and consequences of significant differences in ions diffusion rate in polyacrylate-based ion-selective membranes.

    Science.gov (United States)

    Woźnica, Emilia; Mieczkowski, Józef; Michalska, Agata

    2011-11-21

    The origin and effect of surface accumulation of primary ions within the ion-selective poly(n-butyl acrylate)-based membrane, obtained by thermal polymerization, is discussed. Using a new method, based on the relation between the shape of a potentiometric plot and preconditioning time, the diffusion of copper ions in the membrane was found to be slow (the diffusion coefficient estimated to be close to 10(-11) cm(2) s(-1)), especially when compared to ion-exchanger counter ions--sodium cations diffusion (a diffusion coefficient above 10(-9) cm(2) s(-1)). The higher mobility of sodium ions than those of the copper-ionophore complex results in exposed ion-exchanger role leading to undesirably exposed sensitivity to sodium or potassium ions.

  8. 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.

  9. 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

  10. 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.

  11. 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)

  12. A Low-Cost Inkjet-Printed Aptamer-Based Electrochemical Biosensor for the Selective Detection of Lysozyme

    Directory of Open Access Journals (Sweden)

    Niazul Islam Khan

    2018-01-01

    Full Text Available Recently, inkjet-printing has gained increased popularity in applications such as flexible electronics and disposable sensors, as well as in wearable sensors because of its multifarious advantages. This work presents a novel, low-cost immobilization technique using inkjet-printing for the development of an aptamer-based biosensor for the detection of lysozyme, an important biomarker in various disease diagnosis. The strong affinity between the carbon nanotube (CNT and the single-stranded DNA is exploited to immobilize the aptamers onto the working electrode by printing the ink containing the dispersion of CNT-aptamer complex. The inkjet-printing method enables aptamer density control, as well as high resolution patternability. Our developed sensor shows a detection limit of 90 ng/mL with high target selectivity against other proteins. The sensor also demonstrates a shelf-life for a reasonable period. This technology has potential for applications in developing low-cost point-of-care diagnostic testing kits for home healthcare.

  13. Substrate selection for fundamental studies of electrocatalysts and photoelectrodes: inert potential windows in acidic, neutral, and basic electrolyte.

    Directory of Open Access Journals (Sweden)

    Jesse D Benck

    Full Text Available The selection of an appropriate substrate is an important initial step for many studies of electrochemically active materials. In order to help researchers with the substrate selection process, we employ a consistent experimental methodology to evaluate the electrochemical reactivity and stability of seven potential substrate materials for electrocatalyst and photoelectrode evaluation. Using cyclic voltammetry with a progressively increased scan range, we characterize three transparent conducting oxides (indium tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide and four opaque conductors (gold, stainless steel 304, glassy carbon, and highly oriented pyrolytic graphite in three different electrolytes (sulfuric acid, sodium acetate, and sodium hydroxide. We determine the inert potential window for each substrate/electrolyte combination and make recommendations about which materials may be most suitable for application under different experimental conditions. Furthermore, the testing methodology provides a framework for other researchers to evaluate and report the baseline activity of other substrates of interest to the broader community.

  14. 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

  15. Electrochemical capacitor

    Science.gov (United States)

    Anderson, Marc A.; Liu, Kuo -Chuan; Mohr, Charles M.

    1999-10-05

    An inexpensive porous metal oxide material having high surface area, good conductivity and high specific capacitance is advantageously used in an electrochemical capacitor. The materials are formed in a sol-gel process which affords control over the properties of the resultant metal oxide materials.

  16. Electrochemical construction

    Science.gov (United States)

    Einstein, Harry; Grimes, Patrick G.

    1983-08-23

    An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

  17. Electrochemical device

    Science.gov (United States)

    Grimes, Patrick G.; Einstein, Harry; Bellows, Richard J.

    1988-01-12

    A tunnel protected electrochemical device features channels fluidically communicating between manifold, tunnels and cells. The channels are designed to provide the most efficient use of auxiliary power. The channels have a greater hydraulic pressure drop and electrical resistance than the manifold. This will provide a design with the optimum auxiliary energy requirements.

  18. Electrochemical Cell

    DEFF Research Database (Denmark)

    1999-01-01

    The invention relates to a rechargeable electrochemical cell comprising a negative electrode, an electrolyte and a positive electrode in which the positive electrode structure comprises a lithium cobalt manganese oxide of the composition Li¿2?Co¿y?Mn¿2-y?O¿4? where 0 ... for capacity losses in lithium ion cells and lithium-alloy cells....

  19. 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

  20. 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.

  1. 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)

  2. Enhanced Lithium- and Sodium-Ion Storage in an Interconnected Carbon Network Comprising Electronegative Fluorine.

    Science.gov (United States)

    Hong, Seok-Min; Etacheri, Vinodkumar; Hong, Chulgi Nathan; Choi, Seung Wan; Lee, Ki Bong; Pol, Vilas G

    2017-06-07

    Fluorocarbon (C x F y ) anode materials were developed for lithium- and sodium-ion batteries through a facile one-step carbonization of a single precursor, polyvinylidene fluoride (PVDF). Interconnected carbon network structures were produced with doped fluorine in high-temperature carbonization at 500-800 °C. The fluorocarbon anodes derived from the PVDF precursor showed higher reversible discharge capacities of 735 mAh g -1 and 269 mAh g -1 in lithium- and sodium-ion batteries, respectively, compared to the commercial graphitic carbon. After 100 charge/discharge cycles, the fluorocarbon showed retentions of 91.3% and 97.5% in lithium (at 1C) and sodium (at 200 mA g -1 ) intercalation systems, respectively. The effects of carbonization temperature on the electrochemical properties of alkali metal ion storage were thoroughly investigated and documented. The specific capacities in lithium- and sodium-ion batteries were dependent on the fluorine content, indicating that the highly electronegative fluorine facilitates the insertion/extraction of lithium and sodium ions in rechargeable batteries.

  3. Effect of the fluorination technique on the surface-fluorination patterning of double-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Lyubov G. Bulusheva

    2017-08-01

    Full Text Available Double-walled carbon nanotubes (DWCNTs are fluorinated using (1 fluorine F2 at 200 °C, (2 gaseous BrF3 at room temperature, and (3 CF4 radio-frequency plasma functionalization. These have been comparatively studied using transmission electron microscopy and infrared, Raman, X-ray photoelectron, and near-edge X-ray absorption fine structure (NEXAFS spectroscopy. A formation of covalent C–F bonds and a considerable reduction in the intensity of radial breathing modes from the outer shells of DWCNTs are observed for all samples. Differences in the electronic state of fluorine and the C–F vibrations for three kinds of the fluorinated DWCNTs are attributed to distinct local surroundings of the attached fluorine atoms. Possible fluorine patterns realized through a certain fluorination technique are revealed from comparison of experimental NEXAFS F K-edge spectra with quantum-chemical calculations of various models. It is proposed that fluorination with F2 and BrF3 produces small fully fluorinated areas and short fluorinated chains, respectively, while the treatment with CF4 plasma results in various attached species, including single or paired fluorine atoms and –CF3 groups. The results demonstrate a possibility of different patterning of carbon surfaces through choosing the fluorination method.

  4. Design of a Sensitive and Selective Electrochemical Aptasensor for the Determination of the Complementary cDNA of miRNA-145 Based on the Intercalation and Electrochemical Reduction of Doxorubicin.

    Science.gov (United States)

    Mohamadi, Maryam; Mostafavi, Ali; Torkzadeh-Mahani, Masoud

    2017-11-01

    The aim of this research was the determination of a microRNA (miRNA) using a DNA electrochemical aptasensor. In this biosensor, the complementary complementary DNA (cDNA) of miRNA-145 (a sense RNA transcript) was the target strand and the cDNA of miRNA-145 was the probe strand. Both cDNAs can be the product of the reverse transcriptase-polymerase chain reaction of miRNA. The proposed aptasensor's function was based on the hybridization of target strands with probes immobilized on the surface of a working electrode and the subsequent intercalation of doxorubicin (DOX) molecules functioning as the electroactive indicators of any double strands that formed. Electrochemical transduction was performed by measuring the cathodic current resulting from the electrochemical reduction of the intercalated molecules at the electrode surface. In the experiment, because many DOX molecules accumulated on each target strand on the electrode surface, amplification was inherently easy, without a need for enzymatic or complicated amplification strategies. The proposed aptasensor also had the excellent ability to regenerate as a result of the melting of the DNA duplex. Moreover, the use of DNA probe strands obviated the challenges of working with an RNA probe, such as sensitivity to RNase enzyme. In addition to the linear relationship between the electrochemical signal and the concentration of the target strands that ranged from 2.0 to 80.0 nM with an LOD of 0.27 nM, the proposed biosensor was clearly capable of distinguishing between complementary (target strand) and noncomplementary sequences. The presented biosensor was successfully applied for the quantification of DNA strands corresponding to miRNA-145 in human serum samples.

  5. Electrochemistry behavior of endogenous thiols on fluorine doped tin oxide electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, Luciana; Molero, Leonard; Tapia, Ricardo A.; Rio, Rodrigo del; Valle, M. Angelica del; Antilen, Monica [Departamento de Quimica Inorganica, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Av Vicuna Mackenna 4860, Casilla 306, Correo 22, Macul, Santiago (Chile); Armijo, Francisco, E-mail: jarmijom@uc.cl [Departamento de Quimica Inorganica, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Av Vicuna Mackenna 4860, Casilla 306, Correo 22, Macul, Santiago (Chile)

    2011-10-01

    Highlights: > The first time that fluorine doped tin oxide electrodes are used for the electrooxidation of endogenous thiols. > Low potentials of electrooxidation were obtained for the different thiols. > The electrochemical behavior of thiols depends on the pH and the ionic electroactive species, the electrooxidation proceeds for a process of adsorption of electroactive species on FTO and high values the heterogeneous electron tranfer rate constant of the reaction were obtained. - Abstract: In this work the electrochemical behavior of different thiols on fluorine doped tin oxide (FTO) electrodes is reported. To this end, the mechanism of electrochemical oxidation of glutathione (GSH), cysteine (Cys), homocysteine (HCys) and acetyl-cysteine (ACys) at different pH was investigated. FTO showed electroactivity for the oxidation of the first three thiols at pH between 2.0 and 4.0, but under these conditions no acetyl-cysteine oxidation was observed on FTO. Voltammetric studies of the electro-oxidation of GSH, Cys and HCys showed peaks at about 0.35, 0.29, and 0.28 V at optimum pH 2.4, 2.8 and 3.4, respectively. In addition, this study demonstrated that GSH, Cys and HCys oxidation occurs when the zwitterion is the electro-active species that interact by adsorption on FTO electrodes. The overall reaction involves 4e{sup -}/4H{sup +} and 2e{sup -}/2H{sup +}, respectively, for HCys and for GSH and Cys and high heterogeneous electron transfer rate constants. Besides, the use of FTO for the determination of different thiols was evaluated. Experimental square wave voltammetry shows a linear current vs. concentrations response between 0.1 and 1.0 mM was found for HCys and GSH, indicating that these FTO electrodes are promising candidates for the efficient electrochemical determination of these endogenous thiols.

  6. Dependence of transfer number of fluorine on cation type in glasses of Ba(PO3)2-MeF2 systems (Me=Ba,Sr,Ca,Mg)

    International Nuclear Information System (INIS)

    Pronkin, A.A.

    1978-01-01

    The influence of Ba, Sr, Ca, Mg cations on transfer numbers of fluorine in glasses of Ba(PO 3 ) 2 - MeF 2 pseudobinary systems is studied. Transfer numbers are essentially different in one and the same fluorine ion concentration in glasses, containing various alkali-earth cations: increase of the cation field force brings about decrease of the transfer numbers of fluorine, and the glass-formation region in the Ba-Sr-Ca-Mg series rises. The dependence of transfer numbers of fluorine on the fluorine concentration logarithm is presented. It is established, that alkali-earth metals influence the transfer numbers of fluorine on account of selective interaction with the phosphate constituent of glass structure

  7. Decomposition of Fluorinated Graphene under Heat Treatment

    Czech Academy of Sciences Publication Activity Database

    Plšek, Jan; Drogowska, Karolina; Valeš, Václav; Ek Weis, Johan; Kalbáč, Martin

    2016-01-01

    Roč. 22, č. 26 (2016), s. 8990-8997 ISSN 1521-3765 R&D Projects: GA ČR(CZ) GAP208/12/1062 Institutional support: RVO:61388955 Keywords : fluorination * graphene * photoelectron spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry

  8. 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.

  9. An ultrasensitive and selective electrochemical sensor for determination of estrone 3-sulfate sodium salt based on molecularly imprinted polymer modified carbon paste electrode.

    Science.gov (United States)

    Song, Han; Wang, Yuli; Zhang, Lu; Tian, Liping; Luo, Jun; Zhao, Na; Han, Yajie; Zhao, Feilang; Ying, Xue; Li, Yingchun

    2017-11-01

    A highly sensitive and selective electrochemical sensor based on carbon paste electrode (CPE) modified with molecularly imprinted polymers (MIPs) has been developed for the determination of estrone 3-sulfate sodium salt (ESS). MIPs were prepared in polar medium via bulk polymerization and characterized by scanning electron microscopy and infrared spectroscopy. Cyclic voltammetry was performed to the study preparation process and binding behavior of the MIP-modified CPE (MIP/CPE) toward ESS. The conditions for preparing MIPs and MIP/CPE as well as ESS detection were optimized. Under the optimal experimental conditions, the detection linear range for ESS is 4 × 10 -12 to 6 × 10 -9  M with a limit of detection of 1.18 × 10 -12  M (S/N = 3). In addition, the sensor exhibits high binding affinity toward ESS over its structural analogues with excellent repeatability and stability. The fabricated MIP/CPE was then successfully employed to detect ESS in pregnant mare urine (PMU) without any pretreatment, and the average recoveries were from 99.6 to 104.9% with relative standard deviation less than 3.0%. High-performance liquid chromatography was adopted as a reference to validate the established approach in detecting ESS and their results showed good agreement. The as-prepared sensor has high potential to be a decent tool for on-site determination of ESS in PMU in a fast and convenient manner. Graphical Abstract ᅟ.

  10. Argon Shrouded Plasma Spraying of Tantalum over Titanium for Corrosion Protection in Fluorinated Nitric Acid Media

    Science.gov (United States)

    Vetrivendan, E.; Jayaraj, J.; Ningshen, S.; Mallika, C.; Kamachi Mudali, U.

    2018-02-01

    Argon shrouded plasma spraying (ASPS) was used to deposit a Ta coating on commercially pure Ti (CP-Ti) under inert argon, for dissolver vessel application in the aqueous spent fuels reprocessing plant with high plutonium content. Oxidation during plasma spraying was minimized by shrouding argon system. Porosity and oxide content were controlled by optimizing the spraying parameters, to obtain a uniform and dense Ta coating. The Ta particle temperature and velocity were optimized by judiciously controlling the spray parameters, using a spray diagnostic charge-coupled device camera. The corrosion resistance of the Ta coatings developed by ASPS was investigated by electrochemical studies in 11.5 M HNO3 and 11.5 M HNO3 + 0.05 M NaF. Similarly, the durability of the ASPS Ta coating/substrate was evaluated as per ASTM A262 Practice-C test in boiling nitric acid and fluorinated nitric acid for 240 h. The ASPS Ta coating exhibited higher corrosion resistance than the CP-Ti substrate, as evident from electrochemical studies, and low corrosion rate with excellent coating stability in boiling nitric, and fluorinated nitric acid. The results of the present study revealed that tantalum coating by ASPS is a promising strategy for improving the corrosion resistance in the highly corrosive reprocessing environment.

  11. 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.

  12. Multiwall carbon nanotubes decorated with FeCr{sub 2}O{sub 4}, a new selective electrochemical sensor for amoxicillin determination

    Energy Technology Data Exchange (ETDEWEB)

    Ensafi, Ali Asghar, E-mail: Ensafi@cc.iut.ac.ir; Allafchian, Ali Reza; Rezaei, Behzad [Isfahan University of Technology, Department of Chemistry (Iran, Islamic Republic of)

    2012-11-15

    FeCr{sub 2}O{sub 4} nanoparticles were synthesized and then multiwall carbon nanotubes (MWCNTs) were decorated with FeCr{sub 2}O{sub 4} nanoparticles. The new nanoparticles were characterized with different techniques such as vibrating sample magnetometer, Fourier transform infrared spectroscopy, scanning surface microscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. The results of the study confirm that the particles are pure FeCr{sub 2}O{sub 4}-MWCNTs with a cubic structure. No diffraction peaks of other impurities such as FeO or Cr{sub 2}O{sub 3} were observed. The diffractive peaks of FeCr{sub 2}O{sub 4}-MWCNTs are broadened, implying that the crystalline size of FeCr{sub 2}O{sub 4}-MWCNTs particles is quite small. The mean particle size of FeCr{sub 2}O{sub 4}-MWCNTs calculated by Scherrer equation is about 25 nm, whereas the existence of particles with less than 30 nm size at FeCr{sub 2}O{sub 4}-MWCNTs is clearly reflected in 2D and 3D AFM images. The TEM image confirms that the spaghetti-like FeCr{sub 2}O{sub 4}-MWCNTs formed a porous structure. The synthesized FeCr{sub 2}O{sub 4}-MWCNTs nanoparticles could be used as a new electrocatalysis for voltammetric determination of amoxicillin (AMC). Under the optimized conditions at pH 7.5 and in differential pulse voltammetry, the oxidation peak current of AMC at the surface of the mediator has two linear dynamic ranges including 0.1-10.0 and 10.0-70.0 {mu}mol L{sup -1}. The detection limit of 0.05 {mu}mol L{sup -1} was achieved. The influence of potential interfering compounds on the selectivity was studied. Finally, the modified electrode showed good sensitivity, selectivity, and stability for the determination of AMC in real samples.

  13. 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.

  14. Graphene nanoflakes on transparent glass electrode sensor for electrochemical sensing of anti-diabetic drug.

    Science.gov (United States)

    Narang, Jagriti; Malhotra, Nitesh; Singhal, Chaitali; Bhatia, Rishabh; Kathuria, Vikas; Jain, Manan

    2017-04-01

    Metformin (Mf) plays a major role in controlling insulin level of individuals at risk of developing diabetes mellitus. Overdose of Mf can cause lactic acidosis, diarrhoea, cough, or hoarseness, etc. These particulars point out the identification for selective and sensitive methods of Mf determination. In the present work, graphene nanoflakes-polymethylene blue (GNF-PMB) nano-composites were developed onto fluorine-doped tin oxide (SnO 2 /F) coated glass substrates for electrochemical sensing of Mf using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The developed sensor shows quick response time (10 s), linearity as 10-10 3  µM, LOD (0.1 nM), and good shelf life (10 weeks). Attempts have been made to utilize this electrode for estimation of Mf in urine samples. Configured as a highly responsive, reproducible Mf sensor, it combines the electrical properties of GNF and stable electron transfer of PMB. The newly developed Mf sensor presents a promising candidate in point-of-care diagnosis.

  15. 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.

  16. 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.

  17. 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

  18. 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)

  19. Electrochemical cell

    Science.gov (United States)

    Kaun, T.D.

    An improved secondary electrochemical cell is disclosed having a negative electrode of lithium aluminum, a positive electrode of iron sulfide, a molten electrolyte of lithium chloride and potassium chloride, and the combination that the fully charged theoretical capacity of the negative electrode is in the range of 0.5 to 1.0 that of the positive electrode. The cell thus is negative electrode limiting during discharge cycling. Preferably, the negative electrode contains therein, in the approximate range of 1 to 10 volume % of the electrode, an additive from the materials of graphitized carbon, aluminum-iron alloy, and/or magnesium oxide.

  20. Resolving intramolecular-distortion changes induced by the partial fluorination of pentacene adsorbed on Cu(111)

    Science.gov (United States)

    Franco-Cañellas, Antoni; Wang, Qi; Broch, Katharina; Shen, Bin; Gerlach, Alexander; Bettinger, Holger F.; Duhm, Steffen; Schreiber, Frank

    2018-04-01

    We experimentally quantify the molecular bending of a partially fluorinated pentacene (PEN) compound, namely 2,3,9,10-tetrafluoropentacene (F4PEN), adsorbed on Cu(111). By means of the x-ray standing wave (XSW) technique, we directly measure the adsorption distance of three inequivalent carbon sites, the fluorine atoms as well as the total and backbone carbon average adsorption distances. The precise positioning of different sites within the carbon core allows us to resolve two adsorption behaviors, namely a PEN-like strong coupling between the backbone and the substrate, and a repulsive interaction involving the fluorinated short molecular edges, which are 0.91 ±0.09 Å above the central benzene ring. This finding is further supported by additional electronic and in-plane-structure measurements, thus showing that the selective fluorination of a PEN molecule has only a local conformational effect and it is not sufficient to modify its interface properties. Yet, in the multilayer regime, the electronic and growth properties of the film differ completely from those of PEN and its perfluorinated derivative.

  1. 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

  2. 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.

  3. Electrochemical attosyringe.

    Science.gov (United States)

    Laforge, François O; Carpino, James; Rotenberg, Susan A; Mirkin, Michael V

    2007-07-17

    The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10(-18) to 10(-12) liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.

  4. A rapid stereoselective synthesis of fluorinated carbohydrates

    International Nuclear Information System (INIS)

    Adam, M.J.; Neeser, J-R.; Hall, L.D.; Pate, B.D.

    1983-01-01

    Acetyl hypofluorite has been added to six unsaturated carbohydrates which contain the vinyl ether moiety. All reactions were rapid (less than 5 min.) at -78 degrees C and gave, with one exception, high yields of isomerically pure products. The hypofluorite was shown to add exclusively in a cis mode and with a strong preference for a particular 'face' of the double bond. As well as the syntheses, NMR data and preferred conformations for the fluorinated products are also discussed

  5. Kinetic mechanism for modeling of electrochemical reactions.

    Science.gov (United States)

    Cervenka, Petr; Hrdlička, Jiří; Přibyl, Michal; Snita, Dalimil

    2012-04-01

    We propose a kinetic mechanism of electrochemical interactions. We assume fast formation and recombination of electron donors D- and acceptors A+ on electrode surfaces. These mediators are continuously formed in the electrode matter by thermal fluctuations. The mediators D- and A+, chemically equivalent to the electrode metal, enter electrochemical interactions on the electrode surfaces. Electrochemical dynamics and current-voltage characteristics of a selected electrochemical system are studied. Our results are in good qualitative agreement with those given by the classical Butler-Volmer kinetics. The proposed model can be used to study fast electrochemical processes in microsystems and nanosystems that are often out of the thermal equilibrium. Moreover, the kinetic mechanism operates only with the surface concentrations of chemical reactants and local electric potentials, which facilitates the study of electrochemical systems with indefinable bulk.

  6. 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

  7. [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.

  8. 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

  9. 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.

  10. 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

  11. Fluorinated tripodal receptors for potentiometric chloride detection in biological fluids.

    Science.gov (United States)

    Pankratova, Nadezda; Cuartero, Maria; Jowett, Laura A; Howe, Ethan N W; Gale, Philip A; Bakker, Eric; Crespo, Gastón A

    2018-01-15

    Fluorinated tripodal compounds were recently reported to be efficient transmembrane transporters for a series of inorganic anions. In particular, this class of receptors has been shown to be suitable for the effective complexation of chloride, nitrate, bicarbonate and sulfate anions via hydrogen bonding. The potentiometric properties of urea and thiourea-based fluorinated tripodal receptors are explored here for the first time, in light of the need for reliable sensors for chloride monitoring in undiluted biological fluids. The ion selective electrode (ISE) membranes with tren-based tris-urea bis(CF 3 ) tripodal compound (ionophore I) were found to exhibit the best selectivity for chloride over major lipophilic anions such as salicylate ( [Formula: see text] ) and thiocyanate ( [Formula: see text] ). Ionophore I-based ISEs were successfully applied for chloride determination in undiluted human serum as well as artificial serum sample, the slope of the linear calibration at the relevant background of interfering ions being close to Nernstian (49.8±1.7mV). The results of potentiometric measurements were confirmed by argentometric titration. Moreover, the ionophore I-based ISE membrane was shown to exhibit a very good long-term stability of potentiometric performance over the period of 10 weeks. Nuclear magnetic resonance (NMR) titrations, potentiometric sandwich membrane experiments and density functional theory (DFT) computational studies were performed to determine the binding constants and suggest 1:1 complexation stoichiometry for the ionophore I with chloride as well as salicylate. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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)

  20. Microfluidic electrochemical device and process for chemical imaging and electrochemical analysis at the electrode-liquid interface in-situ

    Science.gov (United States)

    Yu, Xiao-Ying; Liu, Bingwen; Yang, Li; Zhu, Zihua; Marshall, Matthew J.

    2016-03-01

    A microfluidic electrochemical device and process are detailed that provide chemical imaging and electrochemical analysis under vacuum at the surface of the electrode-sample or electrode-liquid interface in-situ. The electrochemical device allows investigation of various surface layers including diffuse layers at selected depths populated with, e.g., adsorbed molecules in which chemical transformation in electrolyte solutions occurs.

  1. [Fluorine as a factor in premature aging].

    Science.gov (United States)

    Machoy-Mokrzyńska, Anna

    2004-01-01

    The use of fluorine compounds in various areas of medicine, particularly in dentistry, as well as in agriculture and industry became very popular in the second half of the 20th century. Fluorine owed this widespread acceptance to observations that its compounds stimulate ossification processes and reduce the prevalence of caries. Unfortunately, growing expectations overshadowed the truth regarding interactions of fluoride on the molecular level. The fact was often ignored that fluoride is toxic, even though laboratory data stood for a careful approach to the benefits of usage. Excessive exposure to fluoride may lead to acute poisoning, hyperemia, cerebral edema, and degeneration of the liver and kidneys. Acute intoxication through the airways produces coughing, choking, and chills, followed by fever and pulmonary edema. Concentrated solutions of fluorine compounds produce difficult to heal necrotic lesions. In spite of these dramatic symptoms, acute intoxications are relatively rare; the more common finding is chronic intoxication attributable to the universal presence of fluorine compounds in the environment. The first noticeable signs of excessive exposure to fluoride in contaminated water, air, and food products include discolorations of the enamel. Dental fluorosis during tooth growth and loss of dentition in adulthood are two consequences of chronic intoxication with fluorine compounds. Abnormalities in mineralization processes affect by and large the osteoarticular system and are associated with changes in the density and structure of the bone presenting as irregular mineralization of the osteoid. Fluorine compounds also act on the organic part of supporting tissues, including collagen and other proteins, and on cells of the connective tissue. These interactions reduce the content of collagen proteins, modify the structure and regularity of collagen fibers, and induce mineralization of collagen. Interactions with cells produce transient activation of

  2. 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.

  3. 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.

  4. Functionality Selection Principle for High Voltage Lithium-ion Battery Electrolyte Additives

    Energy Technology Data Exchange (ETDEWEB)

    Su, Chi-Cheung; He, Meinan [Department; Peebles, Cameron; Zeng, Li; Tornheim, Adam; Liao, Chen; Zhang, Lu; Wang, Jie; Wang, Yan [Department; Zhang, Zhengcheng

    2017-08-30

    A new class of electrolyte additives based on cyclic fluorinated phosphate esters was rationally designed and identified as being able to stabilize the surface of a LiNi0.5Mn0.3Co0.2O2 (NMC532) cathode when cycled at potentials higher than 4.6 V vs Li+/Li. Cyclic fluorinated phosphates were designed to incorporate functionalities of various existing additives to maximize their utilization. The synthesis and characterization of these new additives are described and their electrochemical performance in a NMC532/graphite cell cycled between 4.6 and 3.0 V are investigated. With 1.0 wt % 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide (TFEOP) in the conventional electrolyte the NMC532/graphite cell exhibited much improved capacity retention compared to that without any additive. The additive is believed to form a passivation layer on the surface of the cathode via a sacrificial polymerization reaction as evidenced by X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonsance (NMR) analysis results. The rational pathway of a cathode-electrolyte-interface formation was proposed for this type of additive. Both experimental results and the mechanism hypothesis suggest the effectiveness of the additive stems from both the polymerizable cyclic ring and the electron-withdrawing fluorinated alkyl group in the phosphate molecular structure. The successful development of cyclic fluorinated phosphate additives demonstrated that this new functionality selection principle, by incorporating useful functionalities of various additives into one molecule, is an effective approach for the development of new additives.

  5. Effect of post-etch annealing gas composition on the structural and electrochemical properties of Ti2CTx MXene electrodes for supercapacitor applications

    KAUST Repository

    Rakhi, R. B.

    2015-07-08

    Two-dimensional Ti2CTx MXene nanosheets were prepared by the selective etching of Al layer from Ti2AlC MAX phase using HF treatment. The MXene sheets retained the hexagonal symmetry of the parent Ti2AlC MAX phase. Effect of the post-etch annealing ambient (Ar, N2, N2/H2 and Air) on the structure and electrochemical properties of the MXene nanosheets was investigated in detail. After annealing in Air, the MXene sheets exhibited variations in structure, morphology and electrochemical properties as compared to HF treated MAX phase. In contrast, samples annealed in Ar, N2 and N2/H2 ambient retained their original morphology. However, a significant improvement in the supercapacitor performance is observed upon heat treatment in Ar, N2 and N2/H2 ambients. When used in symmetric two-electrode configuration, the MXene sample annealed in N2/H2 atmosphere exhibited the best capacitive performance with specific capacitance value (51 F/g at 1A/g) and high rate performance (86%). This improvement in the electrochemical performance of annealed samples is attributed to highest carbon content, and lowest fluorine content on the surface of the sample upon annealing, while retaining the original 2D layered morphology, and providing maximum access of aqueous electrolyte to the electrodes.

  6. Fluorine-directed 1,2-trans glycosylation of rare sugars.

    Science.gov (United States)

    Aiguabella, Nuria; Holland, Mareike C; Gilmour, Ryan

    2016-06-28

    To reconcile the urgent need to access well defined β-configured 2,6-di-deoxypyranose analogues for chemical biology, with the intrinsic α-selectivity of the native system, the directing role of fluorine at C2 has been explored. Localised partial charge inversion (C-H(δ+)→ C-F(δ-)) elicits a reversal of the substrate-based α-stereoselectivity, irrespective of the protecting group electronics.

  7. 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}.

  8. Determination of non-metallic elements in actinide complexes by oxygen flask combustion (OFC): chlorine and fluorine

    International Nuclear Information System (INIS)

    Ruikar, P.B.; Nagar, M.S.; Subramanian, M.S.

    1989-01-01

    The oxygen flask combustion followed by ion selective electrode measurement has been found to be the most suitable from the point of view of elegance and simplicity for the determination of chlorine and fluorine in actinide complexes. The method has been found to be particularly suitable for glove box adaptation. This report describes the determination of chlorine and fluorine in several uranium complexes, some plutonium complexes and organic analytical standards by this method. The precision and accuracy of the measurements in the milligram level has been found to be quite satisfactory. (author). 16 refs., 11 tabs

  9. 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)

  10. Influence of fluorine on vegetation. [Sinapsis

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, A.

    1915-01-01

    Fluorine occurs in living organisms in 2 forms, always associated with P. In epidermal tissues, nails, hair, and other tissues by which it is finally eliminated, the proportion of F to P is about the same as in apatite. In cells of glands, muscles, and nerves the proportion of F to P sinks 1 to 400. In artificial media of known F content, F in most cases favored the growth, flowering and seed production of plants, especially of Sinapsis. In exceptional cases such as corn, rye and oats, its influence remains doubtful. In rare cases it was found harmful.

  11. Adsorption studies in a fluorinated atmosphere

    International Nuclear Information System (INIS)

    Abassin, J.J.; Barberi, P.; Guillouet, Y.; Hartmanshenn, O.; Lambard, J.; Machefer, J.; Michel, J.

    1966-03-01

    This CEA report deals with the adaptation of conventional or non-conventional apparatus to the measurement of the physical and chemical adsorption of corrosive fluorine-containing gases. Various techniques are reviewed, in particular: - thermogravimetry; - volumetry; - use of radio-active tracers; - calorimetry; - hertzian spectroscopy; - infrared spectroscopy. In each of these cases, problems of corrosion call for the use of special techniques which require the extensive use of pure nickel and aluminium or certain of their alloys. Diagrams of the apparatus and some examples of applications are given, together with some details of the performances obtained and of the main drawbacks. (authors) [fr

  12. 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...

  13. 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.

  14. 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

  15. Enhanced Bioactivity and Bacteriostasis of Surface Fluorinated Polyetheretherketone.

    Science.gov (United States)

    Chen, Meiling; Ouyang, Liping; Lu, Tao; Wang, Heying; Meng, Fanhao; Yang, Yan; Ning, Congqin; Ma, Jingzhi; Liu, Xuanyong

    2017-05-24

    Although polyetheretherketone (PEEK) has been considered as a potential orthopedic and dental application material due to its similar elastic modulus as bones, inferior osseointegration and bacteriostasis of PEEK hampers its clinical application. In this work, fluorinated PEEK was constructed via plasma immersion ion implantation (PIII) followed by hydrofluoric acid treatment to ameliorate the osseointegration and antibacterial properties of PEEK. The surface microstructure, composition, and hydrophilicity of all samples were investigated. Rat bone mesenchymal stem cells (rBMSCs) were cultured on their surfaces to estimate bioactivity. The fluorinated PEEK can enhance the cell adhesion, cell spreading, proliferation, and alkaline phosphatase (ALP) activity compared to pristine PEEK. Furthermore, the fluorinated PEEK surface exhibits good bacteriostatic effect against Porphyromonas gingivalis, which is one of the major periodontal pathogens. In summary, we provide an effective route to introduce fluorine and the results reveal that the fluorinated PEEK can enhance the osseointegration and bacteriostasis, which provides a potential candidate for dental implants.

  16. Sensitive and selective determination of gallic acid in green tea samples based on an electrochemical platform of poly(melamine) film

    Energy Technology Data Exchange (ETDEWEB)

    Su, Ya-Ling; Cheng, Shu-Hua, E-mail: shcheng@ncnu.edu.tw

    2015-12-11

    In this work, an electrochemical sensor coupled with an effective flow-injection amperometry (FIA) system is developed, targeting the determination of gallic acid (GA) in a mild neutral condition, in contrast to the existing electrochemical methods. The sensor is based on a thin electroactive poly(melamine) film immobilized on a pre-anodized screen-printed carbon electrode (SPCE*/PME). The characteristics of the sensing surface are well-characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and surface water contact angle experiments. The proposed assay exhibits a wide linear response to GA in both pH 3 and pH 7.0 phosphate buffer solutions (PBS) under the optimized flow-injection amperometry. The detection limit (S/N = 3) is 0.076 μM and 0.21 μM in the pH 3 and pH 7 solutions, respectively. A relative standard deviation (RSD) of 3.9% is obtained for 57 successive measurements of 50 μM GA in pH 7 solutions. Interference studies indicate that some inorganic salts, catechol, caffeine and ascorbic acid do not interfere with the GA assay. The interference effects from some orthodiphenolic compounds are also investigated. The proposed method and a conventional Folin–Ciocalteu method are applied to detect GA in green tea samples using the standard addition method, and satisfactory spiked recoveries are obtained. - Highlights: • A nitrogen-rich conducting polymer was used for electroanalysis of gallic acid. • The sensor exhibits excellent electrochemical activity in both acidic and neutral media. • Good analytical results in terms of low detection limit and wide linear range are obtained. • The flow-injection amperometric assay is highly stable for continuous 57 replicates measurement (RSD = 3.9%). • The assay shows good recovery for green tea samples.

  17. Sensitive and selective determination of gallic acid in green tea samples based on an electrochemical platform of poly(melamine) film

    International Nuclear Information System (INIS)

    Su, Ya-Ling; Cheng, Shu-Hua

    2015-01-01

    In this work, an electrochemical sensor coupled with an effective flow-injection amperometry (FIA) system is developed, targeting the determination of gallic acid (GA) in a mild neutral condition, in contrast to the existing electrochemical methods. The sensor is based on a thin electroactive poly(melamine) film immobilized on a pre-anodized screen-printed carbon electrode (SPCE*/PME). The characteristics of the sensing surface are well-characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and surface water contact angle experiments. The proposed assay exhibits a wide linear response to GA in both pH 3 and pH 7.0 phosphate buffer solutions (PBS) under the optimized flow-injection amperometry. The detection limit (S/N = 3) is 0.076 μM and 0.21 μM in the pH 3 and pH 7 solutions, respectively. A relative standard deviation (RSD) of 3.9% is obtained for 57 successive measurements of 50 μM GA in pH 7 solutions. Interference studies indicate that some inorganic salts, catechol, caffeine and ascorbic acid do not interfere with the GA assay. The interference effects from some orthodiphenolic compounds are also investigated. The proposed method and a conventional Folin–Ciocalteu method are applied to detect GA in green tea samples using the standard addition method, and satisfactory spiked recoveries are obtained. - Highlights: • A nitrogen-rich conducting polymer was used for electroanalysis of gallic acid. • The sensor exhibits excellent electrochemical activity in both acidic and neutral media. • Good analytical results in terms of low detection limit and wide linear range are obtained. • The flow-injection amperometric assay is highly stable for continuous 57 replicates measurement (RSD = 3.9%). • The assay shows good recovery for green tea samples.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. Low-fluorine Stockwork Molybdenite Deposits

    Science.gov (United States)

    Ludington, Steve; Hammarstrom, Jane; Piatak, Nadine M.

    2009-01-01

    Low-fluorine stockwork molybdenite deposits are closely related to porphyry copper deposits, being similar in their tectonic setting (continental volcanic arc) and the petrology (calc-alkaline) of associated igneous rock types. They are mainly restricted to the Cordillera of western Canada and the northwest United States, and their distribution elsewhere in the world may be limited. The deposits consist of stockwork bodies of molybdenite-bearing quartz veinlets that are present in and around the upper parts of intermediate to felsic intrusions. The deposits are relatively low grade (0.05 to 0.2 percent Mo), but relatively large, commonly >50 million tons. The source plutons for these deposits range from granodiorite to granite in composition; the deposits primarily form in continental margin subduction-related magmatic arcs, often concurrent with formation of nearby porphyry copper deposits. Oxidation of pyrite in unmined deposits or in tailings and waste rock during weathering can lead to development of acid-rock drainage and limonite-rich gossans. Waters associated with low-fluorine stockwork molybdenite deposits tend to be nearly neutral in pH; variable in concentrations of molybdenum (10,000 ug/L); below regulatory guidelines for copper, iron, lead, zinc, and mercury; and locally may exceed guidelines for arsenic, cadmium, and selenium.

  3. The effect of fluorine in low thermal budget polysilicon emitters for SiGe heterojunction bipolar transistors

    International Nuclear Information System (INIS)

    Schiz, F.J.W.

    1999-03-01

    results are explained by the different evolution of defects in as-deposited α-Si and p-Si. The application of fluorine in low thermal budget polysilicon emitters is demonstrated ill a novel self-aligned SiGe heterojunction bipolar transistor concept which is implemented using selective and non-selective epitaxy. The process has the advantage of layer growth ill a single epitaxy step, no growth interfaces in the depletion regions, and oxide isolation as all intrinsic part of the device structure. The device electrical results demonstrate the feasibility of the transistor concept. A detailed analysis of leakage currents is performed and a correlation made with cross-section TEM micrographs. It is shown that E/C leakage is due to punch through at the perimeter of the transistor where the SiGe base is thinner. E/B is explained by the penetration of the E/B depletion region into the extrinsic at the perimeter of the emitter. By directing the extrinsic base implant into single crystal material at the perimeter of the base, both leakage mechanisms can be avoided. (author)

  4. Nanocrystalline CdTe thin films by electrochemical synthesis

    Directory of Open Access Journals (Sweden)

    Ramesh S. Kapadnis

    2013-03-01

    Full Text Available Cadmium telluride thin films were deposited onto different substrates as copper, Fluorine-doped tin oxide (FTO, Indium tin oxide (ITO, Aluminum and zinc at room temperature via electrochemical route. The morphology of the film shows the nanostructures on the deposited surface of the films and their growth in vertical direction. Different nanostructures developed on different substrates. The X-ray diffraction study reveals that the deposited films are nanocrystalline in nature. UV-Visible absorption spectrum shows the wide range of absorption in the visible region. Energy-dispersive spectroscopy confirms the formation of cadmium telluride.

  5. A new electrochemical sensor for highly sensitive and selective detection of nitrite in food samples based on sonochemical synthesized Calcium Ferrite (CaFe2O4) clusters modified screen printed carbon electrode.

    Science.gov (United States)

    Balasubramanian, Paramasivam; Settu, Ramki; Chen, Shen-Ming; Chen, Tse-Wei; Sharmila, Ganapathi

    2018-08-15

    Herein, we report a novel, disposable electrochemical sensor for the detection of nitrite ions in food samples based on the sonochemical synthesized orthorhombic CaFe 2 O 4 (CFO) clusters modified screen printed electrode. As synthesized CFO clusters were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and amperometry (i-t). Under optimal condition, the CFO modified electrode displayed a rapid current response to nitrite, a linear response range from 0.016 to 1921 µM associated with a low detection limit 6.6 nM. The suggested sensor also showed the excellent sensitivity of 3.712 μA μM -1  cm -2 . Furthermore, a good reproducibility, long-term stability and excellent selectivity were also attained on the proposed sensor. In addition, the practical applicability of the sensor was investigated via meat samples, tap water and drinking water, and showed desirable recovery rate, representing its possibilities for practical application. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Microphase separated structure and surface properties of fluorinated polyurethane resin

    International Nuclear Information System (INIS)

    Sudaryanto; Nishino, T.; Hori, Y.; Nakamae, K.

    2000-01-01

    The effect of fluorination on microphase separation and surface properties of segmented polyurethane (PU) resin were investigated. A series of fluorinated polyurethane resin (FPU) was synthesized by reacting a fluorinated diol with aromatic diisocyanate. The microphase separated structure of FPU was studied by thermal analysis, and small angle X-ray scattering (SAXS) as well as wide angle X-ray diffraction (WAXD). The surface structure and properties were characterized by X-ray photoelectron spectroscopy (XPS) and dynamic contact angle measurement. The incorporation of fluorine into hard segment brings the FPU to have a higher hard domain cohesion and increase the phase separation, however localization of fluorine on the surface could not be observed. On the other hands, localization of fluorine on the surface could be achieved for soft segment fluorinated PU without any significant change in microphase separated structure. The result from this study give an important basic information for designing PU coating material with a low surface energy and strong adhesion as well as for development of release film on pressure sensitive adhesive tape. (author)

  7. 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.

  8. Electrochemical energy generation

    International Nuclear Information System (INIS)

    Kreysa, G.; Juettner, K.

    1993-01-01

    The proceedings encompass 40 conference papers belonging to the following subject areas: Baseline and review papers; electrochemical fuel cells; batteries: Primary and secondary cells; electrochemical, regenerative systems for energy conversion; electrochemical hydrogen generation; electrochemistry for nuclear power plant; electrochemistry for spent nuclear fuel reprocessing; energy efficiency in electrochemical processes. There is an annex listing the authors and titles of the poster session, and compacts of the posters can be obtained from the office of the Gesellschaft Deutscher Chemiker, Abteilung Tagungen. (MM) [de

  9. Electrochemical corrosion studies on a selected carbon steel for application in nuclear waste disposal containers: Influence of chemical species in brines on corrosion

    International Nuclear Information System (INIS)

    Farvaque-Bera, A.M.; Smailos, E.

    1994-04-01

    In previous corrosion studies, carbon steels were identified as promising materials for the manufacture of long-lived high-level waste containers that could act as an engineered barrier in a rock-salt repository. In this paper, the influence of chemical species, potentially present in salt brines, on the electrochemical corrosion behavior of the preselected fine-grained steel TStE 355 was studied. The steel was examined at 90 C in a disposal relevant NaCl-rich brine containing various species (Br - , I - , Cu 2+ , Mn 2+ , S 2- , B(OH )4 - and Fe 3+ ) at concentrations between 10 -5 M/I and 10 -1 M/I. (orig.) [de

  10. Characterization of carbon nanotubes decorated with NiFe2O4 magnetic nanoparticles as a novel electrochemical sensor: Application for highly selective determination of sotalol using voltammetry

    International Nuclear Information System (INIS)

    Ensafi, Ali A.; Allafchian, Ali R.; Rezaei, B.; Mohammadzadeh, R.

    2013-01-01

    A magnetic nano‐composite of multiwall carbon nanotube, decorated with NiFe 2 O 4 nanoparticles, was synthesized with citrate sol–gel method. The multiwall carbon nanotubes decorated with NiFe 2 O 4 nanoparticles (NiFe 2 O 4 –MWCNTs) were characterized with different methods such as Fourier transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The new nano-composite acts as a suitable electrocatalyst for the oxidation of sotalol at a potential of 500 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.5–1000 μmol L −1 sotalol with a detection limit of 0.09 μmol L −1 . The modified electrode was used as a novel electrochemical sensor for the determination of sotalol in real samples such as pharmaceutical, patient and safe human urine. - Graphical abstract: Multiwall carbon nanotube, decorated with NiFe 2 O 4 nanoparticles, was prepared using citrate sol–gel method. We characterized the new nanoparticles with different spectroscopic and voltammetric methods. The nano sensor was used as a voltammetric sensor for the determination of trace amounts of sotalol at pH 7.0. Highlights: ► We synthesized and prepared new sensor, multiwall carbon nanotubes decorated with NiFe 2 O 4 . ► Several spectroscopic and voltammetric methods were used to study its characteristics. ► The nanoparticles act as suitable electrocatalyst for the oxidation of sotalol. ► Sotalol could be measured as low as 0.09 μmol L −1 using linear sweep voltammetry.

  11. Sensitive and selective determination of gallic acid in green tea samples based on an electrochemical platform of poly(melamine) film.

    Science.gov (United States)

    Su, Ya-Ling; Cheng, Shu-Hua

    2015-12-11

    In this work, an electrochemical sensor coupled with an effective flow-injection amperometry (FIA) system is developed, targeting the determination of gallic acid (GA) in a mild neutral condition, in contrast to the existing electrochemical methods. The sensor is based on a thin electroactive poly(melamine) film immobilized on a pre-anodized screen-printed carbon electrode (SPCE*/PME). The characteristics of the sensing surface are well-characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and surface water contact angle experiments. The proposed assay exhibits a wide linear response to GA in both pH 3 and pH 7.0 phosphate buffer solutions (PBS) under the optimized flow-injection amperometry. The detection limit (S/N = 3) is 0.076 μM and 0.21 μM in the pH 3 and pH 7 solutions, respectively. A relative standard deviation (RSD) of 3.9% is obtained for 57 successive measurements of 50 μM GA in pH 7 solutions. Interference studies indicate that some inorganic salts, catechol, caffeine and ascorbic acid do not interfere with the GA assay. The interference effects from some orthodiphenolic compounds are also investigated. The proposed method and a conventional Folin-Ciocalteu method are applied to detect GA in green tea samples using the standard addition method, and satisfactory spiked recoveries are obtained. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Evaluation of fluorine-18-labeled alkylating agents as potential synthons for the labeling of oligonucleotides

    Energy Technology Data Exchange (ETDEWEB)

    Vries, E.F.J. de E-mail: e.f.j.de.vries@pet.azg.nl; Vroegh, Joke; Elsinga, P.H.; Vaalburg, Willem

    2003-04-01

    Six fluorine-18-labeled alkylating agents were selected as potentially suitable synthons for the labeling of antisense oligonucleotides. The selected synthons were evaluated in a model reaction with the monomer adenosine 5'-O-thiomonophosphate. Of these synthons, {alpha}-bromo-{alpha}'-[{sup 18}F]fluoro-m-xylene and N-(4-[{sup 18}F]fluorobenzyl)-2-bromoacetamide were found to be the most promising. Labeling with the former synthon was less complicated and time consuming and gave higher uncorrected overall yields. The latter synthon required smaller amounts of the costly precursor to achieve acceptable labeling yields.

  13. Designed fabrication of fluorine-doped carbon coated mesoporous TiO2 hollow spheres for improved lithium storage

    International Nuclear Information System (INIS)

    Geng, Hongbo; Ming, Hai; Ge, Danhua; Zheng, Junwei; Gu, Hongwei

    2015-01-01

    Graphical abstract: Hollow TiO 2 with mesoporous shell (MHTO) was successfully fabricated by a novel and controllable route, followed by fluorine-doped carbon coating the MHTO (MHTO-C/F), with the aim of enhancing the conductivity and stability of structures. - Highlights: • Anatase TiO 2 hollow spheres with mesoporous shells (MHTO) was fabricated via a facile and controllable route, to improve the lithium ion mobility as well as the stability of the architecture. • Fluorine-doped carbon derived from polyvinylidene difluoride was further encapsulated onto TiO 2 hollow spheres to improve the conductivity. • The composites could provide excellent electrochemical performance, which was desirable for the application of TiO 2 as an anode material in lithium ion batteries. - Abstract: In this manuscript, we demonstrated a facile route for the controllable design of “Fluorine (F)-doped carbon” (C/F)-treated TiO 2 hollow spheres with mesoporous shells (MHTO-C/F). The fabrication of this distinct mesoporous hollow structures and the C/F coating could effectively improve the electrolyte permeability and architectural stability, as well as electrical conductivity and lithium ion mobility. As anticipated, MHTO-C/F has several remarkable electrochemical properties, such as a high specific reversible capacity of 252 mA h g −1 , outstanding cycling stability of more than 210 mA h g −1 after 100 cycles at 0.5 C, and good rate performance of around 123 mA h g −1 at 5 C (1 C = 168 mA g −1 ). These properties are highly beneficial for lithium storage

  14. Electronic transport properties of (fluorinated) metal phthalocyanine

    KAUST Repository

    Fadlallah, M M; Eckern, U; Romero, A H; Schwingenschlö gl, Udo

    2015-01-01

    The magnetic and transport properties of the metal phthalocyanine (MPc) and F16MPc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ag) families of molecules in contact with S–Au wires are investigated by density functional theory within the local density approximation, including local electronic correlations on the central metal atom. The magnetic moments are found to be considerably modified under fluorination. In addition, they do not depend exclusively on the configuration of the outer electronic shell of the central metal atom (as in isolated MPc and F16MPc) but also on the interaction with the leads. Good agreement between the calculated conductance and experimental results is obtained. For M = Ag, a high spin filter efficiency and conductance is observed, giving rise to a potentially high sensitivity for chemical sensor applications.

  15. Fluorinated tropinyl esters for application with PET

    International Nuclear Information System (INIS)

    Emran, A.M.; Cherif, A.; Yang, D.J.; Flynn, D.D.

    1993-01-01

    Regulation of muscarinic acetylcholine receptors (MAR) number and function occurs with various exogenous chemicals and pathological conditions. Use of positron emission tomography (PET) has potential in investigating MAR in living humans. This requires synthesis of appropriate radiolabelled tracers with high affinity and high specific activity. Several analogs of atropine and tropacocaine, including fluorinated derivatives, were synthesized and evaluated for their MAR binding affinity. Specific structural alterations correlated with changes in receptor affinity. Substitution was directed primarily on aromatic rings of the acid moieties. In vitro binding assays demonstrated that molecular substitution on some of the compounds retained significant affinity for MAR. Changing the acid moiety on these molecules resulted in a change in MAR affinity. Substitution o the aromatic ring of the acid moiety was also associated with change in receptor affinity. Preliminary radiofluorination has been successful. These compounds provide new tools to study MAR dynamics in the living human brain

  16. Electronic transport properties of (fluorinated) metal phthalocyanine

    KAUST Repository

    Fadlallah, M M

    2015-12-21

    The magnetic and transport properties of the metal phthalocyanine (MPc) and F16MPc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ag) families of molecules in contact with S–Au wires are investigated by density functional theory within the local density approximation, including local electronic correlations on the central metal atom. The magnetic moments are found to be considerably modified under fluorination. In addition, they do not depend exclusively on the configuration of the outer electronic shell of the central metal atom (as in isolated MPc and F16MPc) but also on the interaction with the leads. Good agreement between the calculated conductance and experimental results is obtained. For M = Ag, a high spin filter efficiency and conductance is observed, giving rise to a potentially high sensitivity for chemical sensor applications.

  17. 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.

  18. Toward selective electrochemical 'E-tongue': Potentiometric DO sensor based on sub-micron ZnO-RuO{sub 2} sensing electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zhuiykov, Serge, E-mail: serge.zhuiykov@csiro.au [CSIRO, Materials Science and Engineering Division, 37 Graham Road, Highett, VIC 3190 (Australia); Kats, Eugene [CSIRO, Materials Science and Engineering Division, 37 Graham Road, Highett, VIC 3190 (Australia); Plashnitsa, Vladimir [Research and Education Centre of Carbon Resources, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan); Miura, Norio [KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2011-06-01

    Highlights: > We examine ZnO-doped RuO{sub 2} sensing electrode of DO sensor. > Study of ZnO-RuO{sub 2} confirmed the development of high surface-to-volume ratio. > Developed sensing electrode is insensitive to the presence of various dissolved salts. > 20 mol% ZnO-doped RuO{sub 2} sensing electrode enables maximum DO sensitivity. > We conclude that DO sensor based on ZnO-RuO{sub 2} electrode can work at 11-30 deg. C. - Abstract: Planar dissolved oxygen (DO) sensors based on thick-film ZnO-RuO{sub 2} sensing electrodes (SEs) with different mol% of ZnO were prepared on the alumina substrates using a screen-printing method and their structural and electrochemical properties were closely studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), electrochemical impedance spectroscopy (EIS) and energy-dispersive spectroscopy (EDS) techniques. Structural and electrochemical properties of ZnO-RuO{sub 2}-SEs have been investigated. Interference testing ascertained that the DO sensor based on sub-micron ZnO-RuO{sub 2}-SE is insensitive to the presence of various dissolved ions including Cl{sup -}, Li{sup +}, SO{sub 4}{sup 2-}, NO{sup 3-}, Ca{sup 2+}, PO{sub 4}{sup 3-}, Mg{sup 2+}, Na{sup +} and K{sup +} within a concentration range of 10{sup -7} to 10{sup -1} mol/L for DO measurement from 0.5 to 8.0 ppm in the test solution at a temperature range of 11-30 deg. C. These dissolved salts had practically no effect on the sensor's output potential difference response, whereas Br{sup -} ions had some effects at concentration more than 10{sup -3} mol/L. The relationship between DO and the sensor's potential difference was found to be relatively linear with the maximum sensitivity of -50.6 mV per decade was achieved at 20 mol% ZnO at 7.35 pH. The response and recovery time to pH changes for the planar device based on 20 mol% ZnO-RuO{sub 2}-SE was found to be 10 and 25 s

  19. Photoproduction of Hydrogen by Decamethylruthenocene Combined with Electrochemical Recycling.

    Science.gov (United States)

    Rivier, Lucie; Peljo, Pekka; Vannay, Laurent A C; Gschwend, Grégoire C; Méndez, Manuel A; Corminboeuf, Clémence; Scanlon, Micheál D; Girault, Hubert H

    2017-02-20

    The photoinduced hydrogen evolution reaction (HER) by decamethylruthenocene, Cp 2 *Ru II (Cp*=C 5 Me 5 ), is reported. The use of a metallocene to photoproduce hydrogen is presented as an alternative strategy to reduce protons without involving an additional photosensitizer. The mechanism was investigated by (spectro)electrochemical and spectroscopic (UV/Vis and 1 H NMR) measurements. The photoactivated hydride involved was characterized spectroscopically and the resulting [Cp 2 *Ru III ] + species was electrochemically regenerated in situ on a fluorinated tin oxide electrode surface. A promising internal quantum yield of 25 % was obtained. Optimal experimental conditions- especially the use of weakly coordinating solvent and counterions-are discussed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Control of the new method of determining fluorine

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, A; Clausmann, P

    1912-06-24

    The detection of minute amounts of fluorine by etching is described. The new method has been used to detect 0.01-0.001 mg F in distilled water, natural and artificial mineral waters, minerals, bones, brain and blood.

  1. 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.

  2. Fluorination of Isotopically Labeled Turbostratic and Bernal Stacked Bilayer Graphene

    Czech Academy of Sciences Publication Activity Database

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

    2015-01-01

    Roč. 21, č. 3 (2015), s. 1081-1087 ISSN 1521-3765 R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : fluorination * graphene * bilayers Subject RIV: CF - Physical ; Theoretical Chemistry

  3. 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.

  4. 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...

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. Electrochemical corrosion studies on a selected carbon steel for application in nuclear waste disposal containers: Influence of radiolytic products on corrosion in brines

    International Nuclear Information System (INIS)

    Farvaque-Bera, A.M.; Smailos, E.

    1994-07-01

    In previous corrosion studies, carbon steels were identified as promising materials for the manufacturing of long-lived high-level waste containers that could act as a radionuclide barrier in a rock-salt repository. In the present work, the influence of some important oxidizing radiolytic products generated in gamma irradiated brines on the electrochemical corrosion behaviour of the preselected fine-grained steel TStE 355 was studied. The steel was examined by potentiodynamic and potentiostatic polarization methods at 90 C in a disposal relevant NaCl-rich brine containing radiolytic products such as H 2 O 2 , ClO - , ClO 3 - and ClO 4 - at concentrations between 10 -4 and 10 -2 M/l. The significance of the radiolytic products to steel corrosion depends on their concentration at the metal-brine interface, which in turn, depends on many factors such as the dose rate, the amount of water present in the disposal area, the escape of gases (e.g. H 2 )

  11. On the use of thermal NF3 as the fluorination and oxidation agent in treatment of used nuclear fuels

    Science.gov (United States)

    Scheele, Randall; McNamara, Bruce; Casella, Andrew M.; Kozelisky, Anne

    2012-05-01

    This paper presents results of our investigation on the use of nitrogen trifluoride as a fluorination or fluorination/oxidation agent for separating valuable constituents from used nuclear fuels by exploiting the different volatilities of the constituent fission product and actinide fluorides. Our thermodynamic calculations show that nitrogen trifluoride has the potential to produce volatile fission product and actinide fluorides from oxides and metals that can form volatile fluorides. Simultaneous thermogravimetric and differential thermal analyses show that the oxides of lanthanum, cerium, rhodium, and plutonium are fluorinated but do not form volatile fluorides when treated with nitrogen trifluoride at temperatures up to 550 °C. However, depending on temperature, volatile fluorides or oxyfluorides can form from nitrogen trifluoride treatment of the oxides of niobium, molybdenum, ruthenium, tellurium, uranium, and neptunium. Thermoanalytical studies demonstrate near-quantitative separation of uranium from plutonium in a mixed 80% uranium and 20% plutonium oxide. Our studies of neat oxides and metals suggest that the reactivity of nitrogen trifluoride may be adjusted by temperature to selectively separate the major volatile fuel constituent uranium from minor volatile constituents, such as Mo, Tc, Ru and from the non-volatile fuel constituents based on differences in their reaction temperatures and kinetic behaviors. This reactivity is novel with respect to that reported for other fluorinating reagents F2, BrF5, ClF3.

  12. Tuning the Electronic Structure of Titanium Oxide Support to Enhance the Electrochemical Activity of Platinum Nanoparticles

    KAUST Repository

    Shi, Feifei

    2013-09-11

    Two times higher activity and three times higher stability in methanol oxidation reaction, a 0.12 V negative shift of the CO oxidation peak potential, and a 0.07 V positive shift of the oxygen reaction potential compared to Pt nanoparticles on pristine TiO2 support were achieved by tuning the electronic structure of the titanium oxide support of Pt nanoparticle catalysts. This was accomplished by adding oxygen vacancies or doping with fluorine. Experimental trends are interpreted in the context of an electronic structure model, showing an improvement in electrochemical activity when the Fermi level of the support material in Pt/TiOx systems is close to the Pt Fermi level and the redox potential of the reaction. The present approach provides guidance for the selection of the support material of Pt/TiOx systems and may be applied to other metal-oxide support materials, thus having direct implications in the design and optimization of fuel cell catalyst supports. © 2013 American Chemical Society.

  13. 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)

  14. Sensitive and selective electrochemical determination of quinoxaline-2-carboxylic acid based on bilayer of novel poly(pyrrole) functional composite using one-step electro-polymerization and molecularly imprinted poly(o-phenylenediamine)

    International Nuclear Information System (INIS)

    Yang, Yukun; Fang, Guozhen; Wang, Xiaomin; Pan, Mingfei; Qian, Hailong; Liu, Huilin; Wang, Shuo

    2014-01-01

    Graphical abstract: -- Highlights: •PPY-GO-BiCoPc composite was formed using a simple electrochemical method for the first time. •A novel PoPD-MIP sensor based on PPY-GO-BiCoPc composite had been fabricated. •The PPY-GO-BiCoPc functional composite was introduced to improve performance of the sensor. •Highly sensitive, selective and stable sensor had been achieved. •The established MIP sensor could be promising in food safety analysis. -- Abstract: A facile and efficient molecularly imprinted polymer (MIP) recognition element of electrochemical sensor was fabricated by directly electro-polymerizing monomer o-phenylenediamine (oPD) in the presence of template quinoxaline-2-carboxylic acid (QCA), based on one-step controllable electrochemical modification of poly(pyrrole)-graphene oxide-binuclear phthalocyanine cobalt (II) sulphonate (PPY-GO-BiCoPc) functional composite on glassy carbon electrode (GCE). The MIP film coated on PPY-GO-BiCoPc functional composite decorated GCE (MIP/PPY-GO-BiCoPc/GCE) was presented for the first time. The synergistic effect and electro-catalytic activity toward QCA redox of PPY-GO-BiCoPc functional composite were discussed using various contrast tests. Also, the effect of experimental variables on the current response such as, electro-polymerization cycles, template/monomer ratio, elution condition for template removal, pH of the supporting electrolyte and accumulation time, were investigated in detail. Under the optimized conditions, the proposed MIP sensor possessed a fast rebinding dynamics and an excellent recognition capacity to QCA, while the anodic current response of square wave voltammetry (SWV) was well-proportional to the concentration of QCA in the range of 1.0 × 10 −8 –1.0 × 10 −4 and 1.0 × 10 −4 –5.0 × 10 −4 mol L −1 with a low detection limit of 2.1 nmol L −1 . The established sensor was applied successfully to determine QCA in commercial pork and chicken muscle samples with acceptable

  15. Sensitive and selective electrochemical determination of quinoxaline-2-carboxylic acid based on bilayer of novel poly(pyrrole) functional composite using one-step electro-polymerization and molecularly imprinted poly(o-phenylenediamine)

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yukun; Fang, Guozhen; Wang, Xiaomin; Pan, Mingfei; Qian, Hailong; Liu, Huilin; Wang, Shuo, E-mail: s.wang@tust.edu.cn

    2014-01-02

    Graphical abstract: -- Highlights: •PPY-GO-BiCoPc composite was formed using a simple electrochemical method for the first time. •A novel PoPD-MIP sensor based on PPY-GO-BiCoPc composite had been fabricated. •The PPY-GO-BiCoPc functional composite was introduced to improve performance of the sensor. •Highly sensitive, selective and stable sensor had been achieved. •The established MIP sensor could be promising in food safety analysis. -- Abstract: A facile and efficient molecularly imprinted polymer (MIP) recognition element of electrochemical sensor was fabricated by directly electro-polymerizing monomer o-phenylenediamine (oPD) in the presence of template quinoxaline-2-carboxylic acid (QCA), based on one-step controllable electrochemical modification of poly(pyrrole)-graphene oxide-binuclear phthalocyanine cobalt (II) sulphonate (PPY-GO-BiCoPc) functional composite on glassy carbon electrode (GCE). The MIP film coated on PPY-GO-BiCoPc functional composite decorated GCE (MIP/PPY-GO-BiCoPc/GCE) was presented for the first time. The synergistic effect and electro-catalytic activity toward QCA redox of PPY-GO-BiCoPc functional composite were discussed using various contrast tests. Also, the effect of experimental variables on the current response such as, electro-polymerization cycles, template/monomer ratio, elution condition for template removal, pH of the supporting electrolyte and accumulation time, were investigated in detail. Under the optimized conditions, the proposed MIP sensor possessed a fast rebinding dynamics and an excellent recognition capacity to QCA, while the anodic current response of square wave voltammetry (SWV) was well-proportional to the concentration of QCA in the range of 1.0 × 10{sup −8}–1.0 × 10{sup −4} and 1.0 × 10{sup −4}–5.0 × 10{sup −4} mol L{sup −1} with a low detection limit of 2.1 nmol L{sup −1}. The established sensor was applied successfully to determine QCA in commercial pork and chicken muscle

  16. Aromatic fluorine compounds. VI. Displacement of aryl fluorine in diazonium salts

    Science.gov (United States)

    Finger, G.C.; Oesterling, R.E.

    1956-01-01

    Several chlorofluorobenzenes have been isolated from the Schiemann synthesis of fluorobenzenes. These have been shown to be the products of two side reactions occurring during thermal decomposition of the dry benzenediazonium fluoborate salt containing coprecipitated sodium chloride, an unavoidable contaminant in large preparations involving the use of hydrochloric acid and sodium fluoborate. The major side reaction and its chloro product were unexpected; a unique displacement of fluorine ortho to the diazonium group was observed. Replacement of the diazo group with chlorine was the predicted side reaction which proved to be minor. Conditions causing the side reactions and the isolation and identification of the products are described.

  17. High temperature and pressure electrochemical test station

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2013-01-01

    An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 ◦C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive...... media, as well as localized sampling of gas evolved at the electrodes for gas analysis. A number of safety and engineering design challenges have been addressed. Furthermore, we present a series of electrochemical cell holders that have been constructed in order to accommodate different types of cells...... and facilitate different types of electrochemical measurements. Selected examples of materials and electrochemical cells examined in the test station are provided, ranging from the evaluation of the ionic conductivity of liquid electrolytic solutions immobilized in mesoporous ceramic structures...

  18. Electrode of solid state polymer electrolyte type electrochemical cell; Kobunshi kotai denkaisitsugata denki kagaku seru yo denkyo

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, M [Yamanashi, (Japan); Inoue, M [Tanaka Kikinzoku Kogyo, Tokyo (Japan)

    1996-04-12

    The solid state polymer electrolyte type electrochemical cell (PEMFC) has such problem that the gas diffusion from the resin surface to the catalyst surface is prevented when the coating thickness of cation exchange resin on the catalyst particle and the number of micropores which conduct the gas flow in the catalyst layer are reduced. Resultingly, a sufficiently large current cannot be taken out of the cell. This invention solves the problem. The catalyst layer of electrode of PEMFC consists of a mixture of the conductive catalyst carrier coated with cation exchange resin and the conductive carrier coated with fluorinated hydrocarbon polymer. Adding the water repellent material to the electrode in this way improves the air-passing porosity. As for the cation exchange resin, perfluorocarbon sulfonate or perfluorocarbon carboxylate can be used. For the fluorinated hydrocarbon polymer, fluorinated polyethylene is preferably used. 4 figs., 2 tabs.

  19. 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.

  20. Regulatory requirements for fluorine 18-labelled radiotracers

    International Nuclear Information System (INIS)

    Prigent, A.

    2005-01-01

    Although European and French regulations define radiopharmaceuticals and their different conditions for use, there is no legal status of the radiotracer. Radiotracer is commonly known as a molecular entity administered in tracer doses, that means at very low masses (e.g., nano-mol amounts) and, consequently, without any pharmacological effect. A radiotracer can meet the specifications of either a radiochemical (usually restricted to research in animal models) or a radiopharmaceutical (human use for diagnostic imaging or research projects). Besides the 'proprietary medicinal product', different status have been defined to allow other uses in humans, referring to 'magistral formula' preparation, 'officinal formula' preparation, investigational medicinal product for clinical trials, or to a radiopharmaceutical with a 'patient named authorization'. However, because of the short half-life of fluorine 18 and expanding development of molecular imaging techniques using positron emission tomography (PET), the current regulation is sometimes considered as inappropriate with regard to the small-size production required for such on-site manufactured radiopharmaceuticals. It is often claimed that it could be very difficult to comply with the current Good Manufactured Practice (cGMP). As previously done for radiopharmaceuticals based on monoclonal antibodies, specific adjustments for PET radiopharmaceuticals are under discussion and the 'note for guidance on radiopharmaceuticals' will be soon revised by the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMEA). In many cases, a status of 'magistral' product might be attributed to a PET radiopharmaceutical manufactured according with European Pharmacopoeia monographs. (author)

  1. Recent Advances in Electrochemical Glycobiosensing

    Directory of Open Access Journals (Sweden)

    Germarie Sánchez-Pomales

    2011-01-01

    Full Text Available Biosensors based on electrochemical transduction mechanisms have recently made advances into the field of glycan analysis. These glyco-biosensors offer simple, rapid, sensitive, and economical approaches to the measurement need for rapid glycan analysis for biomarker detection, cancer and disease diagnostics, and bioprocess monitoring of therapeutic glycoproteins. Although the prevalent methods of glycan analysis (high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy provide detailed identification and structural analysis of glycan species, there are significantly few low-cost, rapid glycan assays available for diagnostic and screening applications. Here we review instances in which glyco-biosensors have been used for glycan analysis using a variety of electrochemical transduction mechanisms (e.g., amperometric, potentiometric, impedimetric, and voltammetric, selective binding agents (e.g., lectins and antibodies, and redox species (e.g., enzyme substrates, inorganic, and nanomaterial.

  2. Micropatterning on cylindrical surfaces via electrochemical etching using laser masking

    International Nuclear Information System (INIS)

    Cho, Chull Hee; Shin, Hong Shik; Chu, Chong Nam

    2014-01-01

    Highlights: • Various micropatterns were fabricated on the cylindrical surface of a stainless steel shaft. • Selective electrochemical dissolution was achieved via a series process of laser masking and electrochemical etching. • Laser masking characteristics on the non-planar surface were investigated. • A uniform mask layer was formed on the cylindrical surface via synchronized laser line scanning with a rotary system. • The characteristics of electrochemical etching on the non-planar surface were investigated. - Abstract: This paper proposes a method of selective electrochemical dissolution on the cylindrical surfaces of stainless steel shafts. Selective electrochemical dissolution was achieved via electrochemical etching using laser masking. A micropatterned recast layer was formed on the surface via ytterbium-doped pulsed fiber laser irradiation. The micropatterned recast layer could be used as a mask layer during the electrochemical etching process. Laser masking condition to form adequate mask layer on the planar surface for etching cannot be used directly on the non-planar surface. Laser masking condition changes depending on the morphological surface. The laser masking characteristics were investigated in order to form a uniform mask layer on the cylindrical surface. To minimize factors causing non-uniformity in the mask layer on the cylindrical surface, synchronized laser line scanning with a rotary system was applied during the laser masking process. Electrochemical etching characteristics were also investigated to achieve deeper etched depth, without collapsing the recast layer. Consequently, through a series process of laser masking and electrochemical etching, various micropatternings were successfully performed on the cylindrical surfaces

  3. 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.

  4. Ti atoms in Ru0.3Ti0.7O2 mixed oxides form active and selective sites for electrochemical chlorine evolution

    DEFF Research Database (Denmark)

    Karlsson, Rasmus K. B.; Hansen, Heine Anton; Bligaard, Thomas

    2014-01-01

    affected by the presence of small amounts of Ru dopant, whereas oxygen adsorption is relatively unaffected by Ti dopants in RuO2. The calculations also indicate that coordinatively unsaturated Ti sites on Ru-doped TiO2 and on Ru0.3Ti0.7O2 could form active and selective sites for Cl2 evolution....... These results suggest a reason for why DSA shows a higher chlorine selectivity than RuO2 and propose an experimental test of the hypothesis....

  5. Probing the mechanistic consequences of 5-fluorine substitution on cytidine nucleotide analogue incorporation by HIV-1 reverse transcriptase.

    Science.gov (United States)

    Ray, Adrian S; Schinazi, Raymond F; Murakami, Eisuke; Basavapathruni, Aravind; Shi, Junxing; Zorca, Suzana M; Chu, Chung K; Anderson, Karen S

    2003-05-01

    Beta-D and beta-L-enantiomers of 2',3'-dideoxycytidine analogues are potent chain-terminators and antimetabolites for viral and cellular replication. Seemingly small modifications markedly alter their antiviral and toxicity patterns. This review discusses previously published and recently obtained data on the effects of 5- and 2'-fluorine substitution on the pre-steady state incorporation of 2'-deoxycytidine-5'-monophosphate analogues by HIV-1 reverse transcriptase (RT) in light of their biological activity. The addition of fluorine at the 5-position of the pyrimidine ring altered the kinetic parameters for all nucleotides tested. Only the 5-fluorine substitution of the clinically relevant nucleosides (-)-beta-L-2',3'-dideoxy-3'-thia-5-fluorocytidine (L-FTC, Emtriva), and (+)-beta-D-2',3'-didehydro-2',3'-dideoxy-5-fluorocytidine (D-D4FC, Reverset), caused a higher overall efficiency of nucleotide incorporation during both DNA- and RNA-directed synthesis. Enhanced incorporation by RT may in part explain the potency of these nucleosides against HIV-1. In other cases, a lack of correlation between RT incorporation in enzymatic assays and antiviral activity in cell culture illustrates the importance of other cellular factors in defining antiviral potency. The substitution of fluorine at the 2' position of the deoxyribose ring negatively affects incorporation by RT indicating the steric gate of RT can detect electrostatic perturbations. Intriguing results pertaining to drug resistance have led to a better understanding of HIV-1 RT resistance mechanisms. These insights serve as a basis for understanding the mechanism of action for nucleoside analogues and, coupled with studies on other key enzymes, may lead to the more effective use of fluorine to enhance the potency and selectivity of antiviral agents.

  6. Fluorine-18 labeled tracers for PET studies in the neurosciences

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yu-Shin; Fowler, J.S.

    1995-12-31

    This chapter focuses on fluorine-18, the positron emitter with the longest half-life, the lowest positron energy and probably, the most challenging chemistry. The incorporation of F-18 into organic compounds presents many challenges, including: the need to synthesize and purify the compound within a 2--3 hour time frame; the limited number of labeled precursor molecules; the need to work on a microscale; and the need to produce radiotracers which are chemically and radiochemically pure, sterile and pyrogen-free, and suitable for intravenous injection. The PET method and F-18 labeling of organic molecules are described followed by highlights of the applications of F-18 labeled compounds in the neurosciences and neuropharmacology. It is important to emphasize the essential and pivotal role that organic synthesis has played in the progression of the PET field over the past twenty years from one in which only a handful of institutions possessed the instrumentation and staff to carry out research to the present-day situation where there are more than 200 PET centers worldwide. During this period PET has become an important scientific tool in the neurosciences, cardiology and oncology. It is important to point out that PET is by no means a mature field. The fact that a hundreds of different F-18 labeled compounds have been developed but only a few possess the necessary selectivity and sensitivity in vivo to track a specific biochemical process illustrates this and underscores a major difficulty in radiotracer development, namely the selection of priority structures for synthesis and the complexities of the interactions between chemical compounds and living systems. New developments in rapid organic synthesis are needed in order to investigate new molecular targets and to improve the quantitative nature of PET experiments.

  7. Fluorine-18 labeled tracers for PET studies in the neurosciences

    International Nuclear Information System (INIS)

    Ding, Yu-Shin; Fowler, J.S.

    1995-01-01

    This chapter focuses on fluorine-18, the positron emitter with the longest half-life, the lowest positron energy and probably, the most challenging chemistry. The incorporation of F-18 into organic compounds presents many challenges, including: the need to synthesize and purify the compound within a 2--3 hour time frame; the limited number of labeled precursor molecules; the need to work on a microscale; and the need to produce radiotracers which are chemically and radiochemically pure, sterile and pyrogen-free, and suitable for intravenous injection. The PET method and F-18 labeling of organic molecules are described followed by highlights of the applications of F-18 labeled compounds in the neurosciences and neuropharmacology. It is important to emphasize the essential and pivotal role that organic synthesis has played in the progression of the PET field over the past twenty years from one in which only a handful of institutions possessed the instrumentation and staff to carry out research to the present-day situation where there are more than 200 PET centers worldwide. During this period PET has become an important scientific tool in the neurosciences, cardiology and oncology. It is important to point out that PET is by no means a mature field. The fact that a hundreds of different F-18 labeled compounds have been developed but only a few possess the necessary selectivity and sensitivity in vivo to track a specific biochemical process illustrates this and underscores a major difficulty in radiotracer development, namely the selection of priority structures for synthesis and the complexities of the interactions between chemical compounds and living systems. New developments in rapid organic synthesis are needed in order to investigate new molecular targets and to improve the quantitative nature of PET experiments

  8. 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.

  9. Synchrotron Based Structural Investigations of Mass-Selected PtxGd Nanoparticles and a Gd/Pt(111) Single Crystal for Electrochemical Oxygen Reduction

    DEFF Research Database (Denmark)

    Pedersen, Anders Filsøe; Velazquez-Palenzuela, Amado Andres; Masini, Federico

    2015-01-01

    . 134, 16476–16479 (2012). 3. Velazquez-Palenzuela, A. et al. The enhanced activity of mass-selected PtxGd nanoparticles for oxygen electroreduction. J. Catal. [in press] (2015). doi:10.1016/j.jcat.2014.12.012 4. Perez-Alonso, F. J. et al. The Effect of Size on the Oxygen Electroreduction Activity...

  10. Nanostructured conducting molecularly imprinted polymer for selective extraction of salicylate from urine and serum samples by electrochemically controlled solid-phase micro-extraction

    International Nuclear Information System (INIS)

    Ameli, Akram; Alizadeh, Naader

    2011-01-01

    Highlights: ► Overoxidized polypyrrole templated with salicylate has been utilized as conducting molecular imprinted polymer for EC-SPME. ► This first study reported on conducting molecular imprinted polymer was used to EC-SPME of salicylate. ► Proposed method, is particularly effective in sample clean-up and selective monitoring of salicylate in physiological samples. - Abstract: Overoxidized polypyrrole (OPPy) films templated with salicylate (SA) have been utilized as conducting molecular imprinted polymers (CMIPs) for potential-induced selective solid-phase micro-extraction processes. Various important fabrication factors for controlling the performance of the OPPy films have been investigated using fluorescence spectrometry. Several key parameters such as applied potential for uptake, release, pH of uptake and release solution were varied to achieve the optimum micro-extraction procedure. The film template with SA exhibited excellent selectivity over some interference. The calibration graphs were linear in the ranges of 5 × 10 −8 to 5 × 10 −4 and 1.2 × 10 −6 to 5 × 10 −4 mol mL −1 and the detection limit was 4 × 10 −8 mol L −1 . The OPPy film as the solid-phase micro-extraction absorbent has been applied for the selective clean-up and quantification of trace amounts of SA from physiological samples. The results of scanning electron microscopy (SEM) have confirmed the nano-structure morphologies of the films.

  11. Designer HF-Based Fluorination Reagent: Highly Regioselective Synthesis of Fluoroalkenes and gem-Difluoromethylene Compounds from Alkynes

    Science.gov (United States)

    2015-01-01

    Hydrogen fluoride (HF) and selected nonbasic and weakly coordinating (toward cationic metal) hydrogen-bond acceptors (e.g., DMPU) can form stable complexes through hydrogen bonding. The DMPU/HF complex is a new nucleophilic fluorination reagent that has high acidity and is compatible with cationic metal catalysts. The gold-catalyzed mono- and dihydrofluorination of alkynes using the DMPU/HF complex yields synthetically important fluoroalkenes and gem-difluoromethlylene compounds regioselectively. PMID:25260170

  12. 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

  13. 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

  14. 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)

  15. 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

  16. Nanostructured conducting molecularly imprinted polymer for selective extraction of salicylate from urine and serum samples by electrochemically controlled solid-phase micro-extraction

    Energy Technology Data Exchange (ETDEWEB)

    Ameli, Akram [Department of Chemistry, Faculty of Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Alizadeh, Naader, E-mail: alizaden@modares.ac.ir [Department of Chemistry, Faculty of Science, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of)

    2011-11-30

    Highlights: Black-Right-Pointing-Pointer Overoxidized polypyrrole templated with salicylate has been utilized as conducting molecular imprinted polymer for EC-SPME. Black-Right-Pointing-Pointer This first study reported on conducting molecular imprinted polymer was used to EC-SPME of salicylate. Black-Right-Pointing-Pointer Proposed method, is particularly effective in sample clean-up and selective monitoring of salicylate in physiological samples. - Abstract: Overoxidized polypyrrole (OPPy) films templated with salicylate (SA) have been utilized as conducting molecular imprinted polymers (CMIPs) for potential-induced selective solid-phase micro-extraction processes. Various important fabrication factors for controlling the performance of the OPPy films have been investigated using fluorescence spectrometry. Several key parameters such as applied potential for uptake, release, pH of uptake and release solution were varied to achieve the optimum micro-extraction procedure. The film template with SA exhibited excellent selectivity over some interference. The calibration graphs were linear in the ranges of 5 Multiplication-Sign 10{sup -8} to 5 Multiplication-Sign 10{sup -4} and 1.2 Multiplication-Sign 10{sup -6} to 5 Multiplication-Sign 10{sup -4} mol mL{sup -1} and the detection limit was 4 Multiplication-Sign 10{sup -8} mol L{sup -1}. The OPPy film as the solid-phase micro-extraction absorbent has been applied for the selective clean-up and quantification of trace amounts of SA from physiological samples. The results of scanning electron microscopy (SEM) have confirmed the nano-structure morphologies of the films.

  17. Metal-free reduction of the greenhouse gas sulfur hexafluoride, formation of SF5 containing ion pairs and the application in fluorinations

    KAUST Repository

    Rueping, Magnus

    2017-05-04

    A protocol for the fast and selective two-electron reduction of the potent greenhouse gas sulfur hexafluoride (SF6) by organic electron donors at ambient temperature has been developed. The reaction yields solid ion pairs consisting of donor dications and SF5-anions which can be effectively used in fluorination reactions.

  18. Electrochemical solar energy conversion

    International Nuclear Information System (INIS)

    Gerischer, H.

    1991-01-01

    The principles of solar energy conversion in photoelectrochemical cells are briefly reviewed. Cells for the generation of electric power and for energy storage in form of electrochemical energy are described. These systems are compared with solid state photovoltaic devices, and the inherent difficulties for the operation of the electrochemical systems are analyzed. (author). 28 refs, 10 figs

  19. 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...

  20. Partially fluorinated aarylene polyethers and their ternary blends with PBI and H3PO4

    DEFF Research Database (Denmark)

    Li, Qingfeng; Jensen, Jens Oluf; Pan, Chao

    2008-01-01

    Ternary blend membranes based on sulphonated partially fluorinated arylene polyether, polybenzimidazole (PBI) and phosphoric acid were prepared and characterised as electrolyte for high temperature proton exchange membrane fuel cells. Partially fluorinated arylene polyether was first prepared from...

  1. Electrochemical thermodynamic measurement system

    Science.gov (United States)

    Reynier, Yvan [Meylan, FR; Yazami, Rachid [Los Angeles, CA; Fultz, Brent T [Pasadena, CA

    2009-09-29

    The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

  2. Carbon-Based Solid-State Calcium Ion-Selective Microelectrode and Scanning Electrochemical Microscopy: A Quantitative Study of pH-Dependent Release of Calcium Ions from Bioactive Glass.

    Science.gov (United States)

    Ummadi, Jyothir Ganesh; Downs, Corey J; Joshi, Vrushali S; Ferracane, Jack L; Koley, Dipankar

    2016-03-15

    Solid-state ion-selective electrodes are used as scanning electrochemical microscope (SECM) probes because of their inherent fast response time and ease of miniaturization. In this study, we report the development of a solid-state, low-poly(vinyl chloride), carbon-based calcium ion-selective microelectrode (Ca(2+)-ISME), 25 μm in diameter, capable of performing an amperometric approach curve and serving as a potentiometric sensor. The Ca(2+)-ISME has a broad linear response range of 5 μM to 200 mM with a near Nernstian slope of 28 mV/log[a(Ca(2+))]. The calculated detection limit for Ca(2+)-ISME is 1 μM. The selectivity coefficients of this Ca(2+)-ISME are log K(Ca(2+),A) = -5.88, -5.54, and -6.31 for Mg(2+), Na(+), and K(+), respectively. We used this new type of Ca(2+)-ISME as an SECM probe to quantitatively map the chemical microenvironment produced by a model substrate, bioactive glass (BAG). In acidic conditions (pH 4.5), BAG was found to increase the calcium ion concentration from 0.7 mM ([Ca(2+)] in artificial saliva) to 1.4 mM at 20 μm above the surface. In addition, a solid-state dual SECM pH probe was used to correlate the release of calcium ions with the change in local pH. Three-dimensional pH and calcium ion distribution mapping were also obtained by using these solid-state probes. The quantitative mapping of pH and Ca(2+) above the BAG elucidates the effectiveness of BAG in neutralizing and releasing calcium ions in acidic conditions.

  3. 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

  4. 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

  5. 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.

  6. Friction Properties of Surface-Fluorinated Carbon Nanotubes

    Science.gov (United States)

    Wal, R. L. Vander; Miyoshi, K.; Street, K. W.; Tomasek, A. J.; Peng, H.; Liu, Y.; Margrave, J. L.; Khabashesku, V. N.

    2005-01-01

    Surface modification of the tubular or sphere-shaped carbon nanoparticles through chemical treatment, e.g., fluorination, is expected to significantly affect their friction properties. In this study, a direct fluorination of the graphene-built tubular (single-walled carbon nanotubes) structures has been carried out to obtain a series of fluorinated nanotubes (fluoronanotubes) with variable C(n)F (n =2-20) stoichiometries. The friction coefficients for fluoronanotubes, as well as pristine and chemically cut nanotubes, were found to reach values as low as 0.002-0.07, according to evaluation tests run in contact with sapphire in air of about 40% relative humidity on a ball-on-disk tribometer which provided an unidirectional sliding friction motion. These preliminary results demonstrate ultra-low friction properties and show a promise in applications of surface modified nanocarbons as a solid lubricant.

  7. 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.

  8. 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.

  9. Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

    OpenAIRE

    Maabong Kelebogile; Machatine Augusto G.; Hu Yelin; Braun Artur; Nambala Fred J.; Diale Mmantsae

    2016-01-01

    Abstract Hematite (a Fe2O3) is a promising semiconductor as photoanode in solar hydrogen production from photoelectrolysis of water due to its appropriate band gap low cost and high electrochemical stability in aqueous caustic electrolytes. Operation of such photoanode in a biased photoelectrochemical cell constitutes an anodization with consequent redox reactions at the electrode surface. a Fe2O3 thin film photoanodes were prepared by simple and inexpensive dip coating method on fluorine dop...

  10. PVC-Membrane Potentiometric Electrochemical Sensor Based on 2-(4-Oxopentan-2-ylideneaminoisoindoline-1,3-dione for Selective Determination of Holmium(III

    Directory of Open Access Journals (Sweden)

    Hassan Ali Zamani

    2011-01-01

    Full Text Available 2-(4-Oxopentan-2-ylideneamino isoindoline-1,3-dione (OID was found to be a suitable neutral ionophore in the fabrication of a highly selective Ho3+ membrane sensor. The electrode has a near-Nernstian slope of 19.6±0.5 mV per decade with a wide concentration range between 1.0×10-6 and 1.0×10-2 mol/L in the pH range of 3.5–8.8, having a fast response time (∼5 s and a detection limit of 5.8×10-7 mol/L. This electrode presented very good selectivity and sensitivity towards the Ho3+ ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The practical utility of the electrode has been demonstrated by its use as an indicator electrode for the potentiometric titration of a Ho3+ solution with EDTA and for the determination of Ho3+ ions concentration in mixtures of two and three different ions.

  11. [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.

  12. 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

  13. 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

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Electrochemical gating in scanning electrochemical microscopy

    NARCIS (Netherlands)

    Ahonen, P.; Ruiz, V.; Kontturi, K.; Liljeroth, P.; Quinn, B.M.

    2008-01-01

    We demonstrate that scanning electrochemical microscopy (SECM) can be used to determine the conductivity of nanoparticle assemblies as a function of assembly potential. In contrast to conventional electron transport measurements, this method is unique in that electrical connection to the film is not

  20. Determination of total fluorine in five coal reference materials by proton-induced gamma-ray emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Roelandts, I.; Robaye, G.; Delbrouck-Habaru, J.M.; Weber, G. [University of Liege, Sart (Belgium). Dept. of Geology, Petrology and Geochemistry

    1996-03-01

    The direct non-destructive proton-induced gamma-ray emission (PIGE) technique with a germanium detector was applied to the determination of total fluorine concentration in five coal reference materials (BCR 30, NIST 1632b, NIST 1635, SARM 20 and USGS CLB-1). Duplicate analyses were made from five randomly selected bottles of each coal. Individual data are presented and some problems (calibration, proton stopping power, effects of sample heating by the proton beam, background estimation) which were encountered during this study are discussed. Sensitivity and reproducibility of the determinations, and homogeneity of the coal samples with respect to fluorine contents by analysis of variance were investigated. The present data are also compared with the few published values for these reference samples, including other PIGE data. The use of synthetic standards and spiked samples in the present study suggested that the PIGE method was more accurate than other techniques.

  1. Electrochemical force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kalinin, Sergei V.; Jesse, Stephen; Collins, Liam F.; Rodriguez, Brian J.

    2017-01-10

    A system and method for electrochemical force microscopy are provided. The system and method are based on a multidimensional detection scheme that is sensitive to forces experienced by a biased electrode in a solution. The multidimensional approach allows separation of fast processes, such as double layer charging, and charge relaxation, and slow processes, such as diffusion and faradaic reactions, as well as capturing the bias dependence of the response. The time-resolved and bias measurements can also allow probing both linear (small bias range) and non-linear (large bias range) electrochemical regimes and potentially the de-convolution of charge dynamics and diffusion processes from steric effects and electrochemical reactivity.

  2. A Course in Electrochemical and Corrosion Engineering.

    Science.gov (United States)

    Van Zee, John

    1985-01-01

    Describes a course designed to show similarities between electrochemistry and corrosion engineering and to show graduate students that electrochemical and corrosion engineering can be accomplished by extending their knowledge of chemical engineering models. Includes course outline, textbooks selected, and teaching methods used. (JN)

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Quantification of the fluorine containing drug 5-fluorouracil in cancer cells by GaF molecular absorption via high-resolution continuum source molecular absorption spectrometry

    International Nuclear Information System (INIS)

    Krüger, Magnus; Huang, Mao-Dong; Becker-Roß, Helmut; Florek, Stefan; Ott, Ingo; Gust, Ronald

    2012-01-01

    The development of high-resolution continuum source molecular absorption spectrometry made the quantification of fluorine feasible by measuring the molecular absorption as gallium monofluoride (GaF). Using this new technique, we developed on the example of 5-fluorouracil (5-FU) a graphite furnace method to quantify fluorine in organic molecules. The effect of 5-FU on the generation of the diatomic GaF molecule was investigated. The experimental conditions such as gallium nitrate amount, temperature program, interfering anions (represented as corresponding acids) and calibration for the determination of 5-FU in standard solution and in cellular matrix samples were investigated and optimized. The sample matrix showed no effect on the sensitivity of GaF molecular absorption. A simple calibration curve using an inorganic sodium fluoride solution can conveniently be used for the calibration. The described method is sensitive and the achievable limit of detection is 0.23 ng of 5-FU. In order to establish the concept of “fluorine as a probe in medicinal chemistry” an exemplary application was selected, in which the developed method was successfully demonstrated by performing cellular uptake studies of the 5-FU in human colon carcinoma cells. - Highlights: ► Development of HR-CS MAS for quantification of fluorine bound to organic molecules ► Measuring as molecular absorption of gallium monofluoride ► Quantification of organic-bound fluorine in biological material ► The concept of “fluorine as a probe in medicinal chemistry” could be established

  8. Quantification of the fluorine containing drug 5-fluorouracil in cancer cells by GaF molecular absorption via high-resolution continuum source molecular absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, Magnus [Freie Universitaet Berlin, Institut fuer Pharmazie, Pharmazeutische Chemie, Koenigin-Luise-Str. 2-4, 14195 Berlin (Germany); Huang, Mao-Dong; Becker-Ross, Helmut; Florek, Stefan [Leibniz Institut fuer Analytische Wissenschaften, ISAS-e.V., Department Berlin, Albert-Einstein-Str. 9, 12489 Berlin (Germany); Ott, Ingo [Technische Universitaet Carolo Wilhelmina zu Braunschweig, Institut fuer Medizinische und Pharmazeutische Chemie, Beethovenstr. 55, 38106 Braunschweig (Germany); Gust, Ronald, E-mail: ronald.gust@uibk.ac.at [Universitaet Innsbruck, Institut fuer Pharmazie, Pharmazeutische Chemie, Innrain 80/82, 6020 Innsbruck (Austria)

    2012-03-15

    The development of high-resolution continuum source molecular absorption spectrometry made the quantification of fluorine feasible by measuring the molecular absorption as gallium monofluoride (GaF). Using this new technique, we developed on the example of 5-fluorouracil (5-FU) a graphite furnace method to quantify fluorine in organic molecules. The effect of 5-FU on the generation of the diatomic GaF molecule was investigated. The experimental conditions such as gallium nitrate amount, temperature program, interfering anions (represented as corresponding acids) and calibration for the determination of 5-FU in standard solution and in cellular matrix samples were investigated and optimized. The sample matrix showed no effect on the sensitivity of GaF molecular absorption. A simple calibration curve using an inorganic sodium fluoride solution can conveniently be used for the calibration. The described method is sensitive and the achievable limit of detection is 0.23 ng of 5-FU. In order to establish the concept of 'fluorine as a probe in medicinal chemistry' an exemplary application was selected, in which the developed method was successfully demonstrated by performing cellular uptake studies of the 5-FU in human colon carcinoma cells. - Highlights: Black-Right-Pointing-Pointer Development of HR-CS MAS for quantification of fluorine bound to organic molecules Black-Right-Pointing-Pointer Measuring as molecular absorption of gallium monofluoride Black-Right-Pointing-Pointer Quantification of organic-bound fluorine in biological material Black-Right-Pointing-Pointer The concept of 'fluorine as a probe in medicinal chemistry' could be established.

  9. Fundamentals of electrochemical science

    CERN Document Server

    Oldham, Keith

    1993-01-01

    Key Features* Deals comprehensively with the basic science of electrochemistry* Treats electrochemistry as a discipline in its own right and not as a branch of physical or analytical chemistry* Provides a thorough and quantitative description of electrochemical fundamentals

  10. Electrochemical Analysis of Neurotransmitters

    Science.gov (United States)

    Bucher, Elizabeth S.; Wightman, R. Mark

    2015-07-01

    Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.

  11. Organic electrochemical transistors

    KAUST Repository

    Rivnay, Jonathan; Inal, Sahika; Salleo, Alberto; Owens, Ró isí n M.; Berggren, Magnus; Malliaras, George G.

    2018-01-01

    Organic electrochemical transistors (OECTs) make effective use of ion injection from an electrolyte to modulate the bulk conductivity of an organic semiconductor channel. The coupling between ionic and electronic charges within the entire volume

  12. 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.

  13. 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)

  14. Design and Synthesis of Novel Fluorine-containing Acrylates

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A series of novel fluorine-containing acrylates 6a-6g were synthesized via the condensation of ethyl cyanoacetate and trifluoroacetic anhydride, followed by chloridization and the coupling reaction with amines. These new compounds exhibited some biological activity as preliminary bioassay indicated. A plausible reaction mechanism was outlined and discussed.

  15. 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)

  16. Nitroimidazoles, Quinolones and Oxazolidinones as Fluorine Bearing Antitubercular Clinical Candidates

    Czech Academy of Sciences Publication Activity Database

    Patel, Rahul V.; Keum, Y.S.; Park, S.W.

    2015-01-01

    Roč. 15, č. 14 (2015), s. 1174-1186 ISSN 1389-5575 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Antitubercular drugs * delamanid * fluorine-containing drugs Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.841, year: 2015

  17. Atmospheric Gas-Phase Reactions of Fluorinated Compounds and Alkenes

    DEFF Research Database (Denmark)

    Østerstrøm, Freja From

    Experimental studies have been performed using three different smog chamber setups to investigate the atmospheric chemistry of fluorinated compounds as well as alkenes. The three instruments were at Ford Motor Company, USA, National Center for Atmospheric Research, USA, and Copenhagen Center...

  18. Fluorine profiling after application of various anti-caries gels

    International Nuclear Information System (INIS)

    Zschau, H.E.; Plier, F.; Otto, G.; Wyrwich, C.; Treide, A.

    1990-01-01

    Two newly developed caries-preventing gels were tested together with Elmex on pre-school children over a time of 3 years. Proton-induced gamma-ray emission spectrometry (PIGE) was used to measure the fluorine profiles in milk teeth (incisors). In accordance with the clinical statement the results allow to produce a new anti-caries drug. (orig.)

  19. Effects of low level fluorine pollution in a mountain valley

    Energy Technology Data Exchange (ETDEWEB)

    Bourbon, P; Tournut, J; Alary, J; Rouzaud, J F; Alengrin, F

    1971-02-01

    Fluoride content in the air and forage were determined, and symptoms of chronic fluoride poisoning in cattle raised in a mountain valley accommodating a phosphoric acid production plant were studied systematically over 10 years. The plant, processing phosphates with a fluoride content of 3.8%, emitted 20 kg of F daily. The atmospheric average F concentration ranged from zero to 10 micrograms/cu M, with 90% in the form of hydrofluoric acid and silicotetrafluoride, and 10% in the form of apatite. The fluorine content in forage, ranging from 20 to 50 ppm, and up to 164 ppm in one case, is responsible for pathological symptoms of fluorine poisoning in cattle. Fluorine content of about 30 ppm causes discoloration of the dental enamel in cattle fed such forage over more than 3 years, which corresponds to the fluorine residues of more than 1000 ppm in the jawbones. Periodic limping occurs in cattle fed forage with about 50 ppm of F over 5 years, corresponding to an F content of more than 4000 ppm. Such animals lose weight and yield much less milk than normal ones. Caries and loose teeth in cattle whose jawbones contain F residues of more than 3000 ppm are observed. Osteosis is, however, practically nonexistent. The urine F content, ranging from 2 to 20 ppm, was normal with less than 100 ppm in 60% of all animals. The results show an accumulation of F in bones, and suggest an F content of 20 ppm in forage as a safe limit.

  20. Theoretical lifetimes and fluorescence yields for multiply-ionized fluorine

    International Nuclear Information System (INIS)

    Tunnell, T.W.; Can, C.; Bhalla, C.P.

    1978-01-01

    Theoretical lifetimes and multiplet partial fluorescence yields for various fluorine ions with a single K-shell vacancy were calculated. For few-electron systems, the lifetimes and line fluorescence yields were computed in the intermediate coupling scheme with the inclusion of the effects arising from configuration interactions. 6 references

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Electrochemical stability of subnanometer Pt clusters

    DEFF Research Database (Denmark)

    Quinson, Jonathan; Röefzaad, Melanie; Deiana, Davide

    2018-01-01

    In the present work, the degradation of size-selected Pt nanoclusters is studied under electrochemical conditions. This model catalyst mimics carbon supported Pt nanoclusters and nanoparticles typically employed in proton exchange membrane fuel cells (PEMFCs). Insight into the early stage...... of degradation is given by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and confirmed by transmission electron microscopy (TEM). In contrast to common assumptions, it is demonstrated that even extremely small Pt clusters exhibit a remarkable stability under electrochemical...... - is observed. In light of the findings reported, developing highly-dispersed subnanometer Pt clusters as catalyst for PEMFCs is a realistic approach provided the operation conditions are suitably adjusted. Furthermore, mitigation strategies to improve the stability of few-atoms catalyst under electrochemical...

  6. 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

  7. 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.

  8. Fluorinated poly(ether sulfone) ionomers with disulfonated naphthyl pendants for proton exchange membrane applications

    Science.gov (United States)

    Hu, Zhaoxia; Lu, Yao; Zhang, Xulve; Yan, Xiaobo; Li, Na; Chen, Shouwen

    2018-06-01

    Proton exchange membranes based on fluorinated poly(ether sulfone)s with disulfonated naphthyl pendants (sSPFES) have been successfully prepared by post functionalization through polymeric SNAr reaction. Copolymer structure was confirmed by H-nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy, the physico-chemical properties of the sSPFES membranes were evaluated by thermogravimetric analysis, gel permeation chromatography, electro-chemical impedance spectroscopy, atomic force microscopy, Fenton, water-swelling and fuel cell test. The pendant grafting degree was controlled by varying the feeding amount of the disulfonaphthols, resulting in the ion exchange capacity about 1.28-1.73 mmol/g. The obtained sSPFES membranes were thermal stable, mechanical ductile, and exhibited dimensional change less than 17%, water uptake below 70%, and proton conductivity as high as 0.17-0.28 S/cm at 90°C in water. In a single H2/O2 fuel cell test at 80°C, the sSPFES-B-3.2 membrane (1.61 mmol/g) showed the maximum power output of 593-658 mW/cm2 at 60%-80% relative humidity, indicating their rather promising potential for fuel cell applications.

  9. Patents on Membranes Based on Non-Fluorinated Polymers for Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Choi, So-Won; Kim, Tae-Ho; Cha, Sang-Ho

    2017-07-10

    Vanadium redox flow batteries (VRFBs) have received considerable attention as large-scale electrochemical energy storage systems. In particular, VRFBs offer a higher power and energy density than other RFBs and mitigate undesirable performance fading, such as inevitable ion crossover, because of the unique advantage that only the vanadium ion is employed as the active species in the two electrolytes. The key constituent of VRFBs is a separator to conduct protons and prevent cross-mixing of the positive and negative electrolytes. For this purpose, ion exchange membranes like sulfonated polymer membranes can be used. Although this type of membrane does not have ion exchange groups, it can achieve an ion exchange capacity by the formation of pores. This review highlights the patents on the preparation of non-fluorinated membranes (sulfonated aromatic polymer membranes and porous membranes) as alternatives to high-cost perfluorinated polymers and their VRFB performance. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  10. 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.

  11. 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

  12. Electrochemical non-enzymatic glucose sensors

    International Nuclear Information System (INIS)

    Park, Sejin; Boo, Hankil; Chung, Taek Dong

    2006-01-01

    The electrochemical determination of glucose concentration without using enzyme is one of the dreams that many researchers have been trying to make come true. As new materials have been reported and more knowledge on detailed mechanism of glucose oxidation has been unveiled, the non-enzymatic glucose sensor keeps coming closer to practical applications. Recent reports strongly imply that this progress will be accelerated in 'nanoera'. This article reviews the history of unraveling the mechanism of direct electrochemical oxidation of glucose and making attempts to develop successful electrochemical glucose sensors. The electrochemical oxidation of glucose molecules involves complex processes of adsorption, electron transfer, and subsequent chemical rearrangement, which are combined with the surface reactions on the metal surfaces. The information about the direct oxidation of glucose on solid-state surfaces as well as new electrode materials will lead us to possible breakthroughs in designing the enzymeless glucose sensing devices that realize innovative and powerful detection. An example of those is to introduce nanoporous platinum as an electrode, on which glucose is oxidized electrochemically with remarkable sensitivity and selectivity. Better model of such glucose sensors is sought by summarizing and revisiting the previous reports on the electrochemistry of glucose itself and new electrode materials

  13. Statistical analysis of fluoride levels in human urine and drinking water samples of fluorinated area of punjab (pakistan)

    International Nuclear Information System (INIS)

    Qayyum, M.; Zaman, W.U.; Rehman, R.; Ahmad, B.; Ahmad, M.; Ali, S.; Murtaza, S

    2013-01-01

    Increasing fluoride levels in drinking water of fluorinated areas of world leading to fluorosis. For bio-monitoring of fluorosis patients, fluoride levels were determined in drinking water and human urine samples of different individuals having dental fluorosis and bony deformities from fluorotic area of Punjab (Sham Ki Bhatiyan, Pakistan) and then compared with reference samples of non fluorotic area (Queens Road, Lahore, Pakistan) using ion selective electrode methodology. Fluoride levels in fluorinated area differ significantly from control group (p < 0.05). In drinking water and human urine samples, fluoride levels in fluorinated areas were: 136.192 +- 67.836 and 94.484 +- 36.572 micro molL/sup -1/ respectively, whereas in control samples, fluoride concentrations were: 19.306 +- 2.109 and 47.154 +- 22.685 micro molL/sup -1/ in water and urine samples correspondingly. Pearson's correlation data pointed out the fact that that human urine and water fluoride concentrations have a significant positive dose response relationship with the prevalence of dental and skeletal fluorosis in fluorotic areas having higher fluoride levels in drinking water. (author)

  14. Electrochemical and AFM Characterization of G-Quadruplex Electrochemical Biosensors and Applications

    Science.gov (United States)

    2018-01-01

    Guanine-rich DNA sequences are able to form G-quadruplexes, being involved in important biological processes and representing smart self-assembling nanomaterials that are increasingly used in DNA nanotechnology and biosensor technology. G-quadruplex electrochemical biosensors have received particular attention, since the electrochemical response is particularly sensitive to the DNA structural changes from single-stranded, double-stranded, or hairpin into a G-quadruplex configuration. Furthermore, the development of an increased number of G-quadruplex aptamers that combine the G-quadruplex stiffness and self-assembling versatility with the aptamer high specificity of binding to a variety of molecular targets allowed the construction of biosensors with increased selectivity and sensitivity. This review discusses the recent advances on the electrochemical characterization, design, and applications of G-quadruplex electrochemical biosensors in the evaluation of metal ions, G-quadruplex ligands, and other small organic molecules, proteins, and cells. The electrochemical and atomic force microscopy characterization of G-quadruplexes is presented. The incubation time and cations concentration dependence in controlling the G-quadruplex folding, stability, and nanostructures formation at carbon electrodes are discussed. Different G-quadruplex electrochemical biosensors design strategies, based on the DNA folding into a G-quadruplex, the use of G-quadruplex aptamers, or the use of hemin/G-quadruplex DNAzymes, are revisited. PMID:29666699

  15. Oxidative desulfurization-fluorination of thioethers. Application for the synthesis of fluorinated nitrogen containing building blocks.

    Science.gov (United States)

    Hugenberg, Verena; Fröhlich, Roland; Haufe, Günter

    2010-12-21

    An oxidative desulfurization-fluorination protocol has been used to synthesize (2S)-2-(difluoromethyl)-N-tosylpyrrolidine (6a) and (2S)-2-(trifluoromethyl)-N-tosylpyrrolidine (7a) from the (2S)-prolinol-derived (2S)-2-(4-chlorophenylthiomethyl)-N-tosylpyrrolidine (9) or (2S)-2-(dithian-2-yl)-N-tosylpyrrolidine (5). Efforts to prepare 3,3-difluoroalanine similarly from an N-protected S-aryl-cysteine ester 17 gave only traces of the target compound 18. Instead, an unique N-(α,α-difluorobenzyl)-N-α',α'-dibromoglycine ester 19 was formed by an unprecedented sequence of reaction steps. A plausible mechanism is suggested involving a sulfur-assisted deoxygenation-difluorination of an imino oxygen and a haloform reaction like carbon-carbon bond fission as key-steps. Efforts to prepare (2S)-2-(fluoromethyl)-N-tosylpyrrolidine (12) from (2S)-N-tosylprolinol (3) by treatment with Fluolead™ (1-tert-butyl-4-trifluorosulfanyl-3,5-dimethylbenzene) gave only 5% of the target compound, but 95% of (3R)-3-fluoro-N-tosylpiperidine (11a) by ring enlargement.

  16. Carbon Nanostructures for Tagging in Electrochemical Biosensing: A Review

    Directory of Open Access Journals (Sweden)

    Paloma Yáñez-Sedeño

    2017-01-01

    Full Text Available Growing demand for developing ultrasensitive electrochemical bioassays has led to the design of numerous signal amplification strategies. In this context, carbon-based nanomaterials have been demonstrated to be excellent tags for greatly amplifying the transduction of recognition events and simplifying the protocols used in electrochemical biosensing. This relevant role is due to the carbon-nanomaterials’ large surface area, excellent biological compatibility and ease functionalization and, in some cases, intrinsic electrochemistry. These carbon-based nanomaterials involve well-known carbon nanotubes (CNTs and graphene as well as the more recent use of other carbon nanoforms. This paper briefly discusses the advantages of using carbon nanostructures and their hybrid nanocomposites for amplification through tagging in electrochemical biosensing platforms and provides an updated overview of some selected examples making use of labels involving carbon nanomaterials, acting both as carriers for signal elements and as electrochemical tracers, applied to the electrochemical biosensing of relevant (biomarkers.

  17. Electrochemical surface plasmon spectroscopy-Recent developments and applications

    International Nuclear Information System (INIS)

    Zhang, Nan; Schweiss, Ruediger; Zong, Yun; Knoll, Wolfgang

    2007-01-01

    A survey is given on recent developments and applications of electrochemical techniques combined with surface plasmon resonance (SPR) spectroscopy. Surface plasmon spectroscopy (SPS) and optical waveguide mode spectroscopy make use of evanescent waves on metal-dielectric interfaces and can be conveniently combined with electrochemical methods. Selected examples of applications of high-pressure surface electrochemical plasmon resonance spectroscopy to study supramolecular architectures such as layer-by-layer films of conducting polymers or thin composite films will be presented. Then a combination of SPS with the electrochemical quartz crystal microbalance (EQCM) will be introduced and illustrated with a study on doping/de-doping process of a conducting polymer. This combination allows for simultaneous electrochemical, optical and microgravimetric characterization of interfaces. Finally, new technical developments including integration of SPS into microfluidic devices using a grating coupler and surface plasmon enhanced diffraction will be discussed

  18. Survey of electrochemical production of inorganic compounds. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1980-10-01

    The electrochemical generation of inorganic compounds, excluding chlorine/caustic, has been critically reviewed. About 60 x 10/sup 12/ Btu/y fossil fuel equivalent will be used in the year 2000 for the electrosynthesis of inorganic compounds. Significant energy savings in chlorate production can result from the development of suitable electrocatalysts for lowering the cathodic overpotential. Perchlorates, electrolytic hypochlorite, electrolytic manganese dioxide, fluorine and other miscellaneous compounds use relatively small amounts of electrical energy. Implementation of caustic scrubber technology for stack gas cleanup would result in appreciable amounts of sodium sulfate which could be electrolyzed to regenerate caustic. Hydrogen peroxide, now produced by the alkyl anthraquinone process, could be made electrolytically by a new process coupling anodic oxidation of sulfate with cathodic reduction of oxygen in alkaline solution. Ozone is currently manufactured using energy-inefficient silent discharge equipment. A novel energy-efficient approach which uses an oxygen-enhanced anodic reaction is examined.

  19. Materials for electrochemical capacitors

    Science.gov (United States)

    Simon, Patrice; Gogotsi, Yury

    2008-11-01

    Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

  20. 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

  1. Electrochemical properties of porous carbon black layer as an electron injector into iodide redox couple

    International Nuclear Information System (INIS)

    Kim, Jung-Min; Rhee, Shi-Woo

    2012-01-01

    Highlights: ► Carbon black (CB) porous layer for triiodide (I 3 − ) ion reduction is coated with spray coating method at 120 °C on the fluorine-doped tin oxide glass. ► The electrochemical impedance spectroscopy is analyzed for a symmetric cell and a new circuit model is applied to identify electrochemical parameters. ► Decreased particle size and increased thickness improve the catalytic activity because of the increase in the surface area and the conductivity of the CB layer. - Abstract: Electrochemical properties of carbon black (CB) porous layer as a counter electrode in dye-sensitized solar cells (DSC) are studied. CB electrode for triiodide (I 3 − ) ion reduction is coated with spray coating method on the fluorine-doped tin oxide glass at 120 °C. The CB particle size is varied from 20 nm to 90 nm and the CB electrode thickness is controlled from 1 μm to 9 μm by controlling the spraying time. The electrochemical impedance spectroscopy is analyzed for a symmetric cell and a new circuit model is applied to identify electrochemical parameters. As the CB particle size is decreased, the catalytic activity is improved because of the increase in the surface area and the conductivity of the CB layer. Increased CB electrode thickness also improves the catalytic activity and leads to the low charge transfer resistance at the electrolyte/CB electrode interface. The CB counter electrode with the particle size of 20 nm and the thickness of 9 μm for DSC shows the energy conversion efficiency of 7.2% with the highest fill factor (FF) of 65.6%, which is similar to the Pt counter electrode with FF of 65.8% and the efficiency of 7.6%.

  2. 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.

  3. 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)

  4. 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.

  5. Electrochemical sensor for detection of carcinoma

    International Nuclear Information System (INIS)

    Thakur, Bhawana; Sawant, Shilpa N.; Jayakumar, S.

    2012-01-01

    Detection of carcinoma in early stage is very important for its effective treatment. Although considerable advancement has been made in its detection and treatment, there is a significant need for rapid, low-cost, sensitive, and selective biosensors for detection of cancer. In recent years, electrochemical detection techniques have received much attention due to their rapid response, high sensitivity, and inherent selectivity. They can provide an inexpensive platform for detection of analytes in clinical diagnostics. Conducting polymers are a versatile material for development of electrochemical biosensors. Due to the conducting nature of these polymers, they act as a transducer to convert the biological signal into electrical signal. These polymers also exhibit good biocompatibility, hence are ideal for immobilisation of biological recognition element during the development of the sensor film. Recently author have demonstrated a whole cell based electrochemical biosensor for detection of the pesticide Lindane at very low concentrations. In the present study, we have tried to develop polyaniline based electrochemical sensor for detection of carcinoma. Polyaniline was deposited on gold interdigitated electrodes by electropolymerization using potentiodynamic method. The polymer film was suitably modified to obtain the sensor film for recognition of the tumour cells. Response of the sensor to various tumour cells such as lung cancer cells, human fibrosarcoma cells, prostate cancer cells, breast cancer cells was studied and was compared to that of normal cells. The sensor electrode could detect tumour cells based on the nature of response obtained

  6. A fine-tuned fluorinated MOF addresses the needs for trace CO2 removal and air capture using physisorption.

    KAUST Repository

    Bhatt, Prashant; Belmabkhout, Youssef; Cadiau, Amandine; Adil, Karim; Shekhah, Osama; Shkurenko, Aleksander; Barbour, Leonard J.; Eddaoudi, Mohamed

    2016-01-01

    The development of functional solid-state materials for carbon capture at low carbon dioxide (CO2) concentrations, from con-fined spaces (<0.5 %) and particularly from air (400 ppm), is of prime importance with respect to energy and environment sustainability. Herein, we report the deliberate construction of a hydrolytically stable fluorinated metal-organic framework (MOF), NbOFFIVE-1-Ni, with the proper pore system (size, shape and functionality), ideal for efficient and effective traces carbon dioxide removal. Markedly, the CO2-selective NbOFFIVE-1-Ni exhibits the highest CO2 gravimetric and volumetric uptake (ca. 1.3 mmol/g and 51.4 cm3.cm-3) for physical adsorbents at 400 ppm CO2 and 298 K. Practically, the NbOFFIVE-1-Ni affords the complete CO2 desorption at 328 K under vacuum with an associated moderate energy input of 54 kJ/mol, typical for the full CO2 desorption in reference physical adsorbents but considerably lower than the conventional chemical sorbents. Noticeably, the contracted square-like channels, affording the close proximity of the fluorine centers, permitted the enhancement of the CO2-framework interactions and subsequently the attainment of an unprecedented CO2-selectivity at very low CO2 concentrations. The precise localization of the adsorbed CO2 at the vicinity of the periodically aligned fluorine centers, promoting the selective adsorption of CO2, is evidenced by the single-crystal X-ray diffraction study on the NbOFFIVE-1-Ni hosting CO2 molecules. Cyclic CO2/N2 mixed-gas column breakthrough experiments under dry and humid conditions corroborate the excellent CO2-selectivity under practical carbon capture conditions. Pertinently, the no-table hydrolytic stability positions the NbOFFIVE-1-Ni as the new benchmark adsorbent for direct air capture and CO2 removal from confined spaces.

  7. A fine-tuned fluorinated MOF addresses the needs for trace CO2 removal and air capture using physisorption.

    KAUST Repository

    Bhatt, Prashant

    2016-07-08

    The development of functional solid-state materials for carbon capture at low carbon dioxide (CO2) concentrations, from con-fined spaces (<0.5 %) and particularly from air (400 ppm), is of prime importance with respect to energy and environment sustainability. Herein, we report the deliberate construction of a hydrolytically stable fluorinated metal-organic framework (MOF), NbOFFIVE-1-Ni, with the proper pore system (size, shape and functionality), ideal for efficient and effective traces carbon dioxide removal. Markedly, the CO2-selective NbOFFIVE-1-Ni exhibits the highest CO2 gravimetric and volumetric uptake (ca. 1.3 mmol/g and 51.4 cm3.cm-3) for physical adsorbents at 400 ppm CO2 and 298 K. Practically, the NbOFFIVE-1-Ni affords the complete CO2 desorption at 328 K under vacuum with an associated moderate energy input of 54 kJ/mol, typical for the full CO2 desorption in reference physical adsorbents but considerably lower than the conventional chemical sorbents. Noticeably, the contracted square-like channels, affording the close proximity of the fluorine centers, permitted the enhancement of the CO2-framework interactions and subsequently the attainment of an unprecedented CO2-selectivity at very low CO2 concentrations. The precise localization of the adsorbed CO2 at the vicinity of the periodically aligned fluorine centers, promoting the selective adsorption of CO2, is evidenced by the single-crystal X-ray diffraction study on the NbOFFIVE-1-Ni hosting CO2 molecules. Cyclic CO2/N2 mixed-gas column breakthrough experiments under dry and humid conditions corroborate the excellent CO2-selectivity under practical carbon capture conditions. Pertinently, the no-table hydrolytic stability positions the NbOFFIVE-1-Ni as the new benchmark adsorbent for direct air capture and CO2 removal from confined spaces.

  8. Synthesis of fluorinated ReCl(4,4'-R2-2,2'-bipyridine)(CO)3 complexes and their photophysical characterization in CH3CN and supercritical CO2.

    Science.gov (United States)

    Doherty, Mark D; Grills, David C; Fujita, Etsuko

    2009-03-02

    Two new CO(2)-soluble rhenium(I) bipyridine complexes bearing the fluorinated alkyl ligands 4,4'-(C(6)F(13)CH(2)CH(2)CH(2))(2)-2,2'-bipyridine (1a), and 4,4'-(C(8)F(17)CH(2)CH(2)CH(2))(2)-2,2'-bipyridine (1b) have been prepared and their photophysical properties investigated in CH(3)CN and supercritical CO(2). Electrochemical and spectroscopic characterization of these complexes in CH(3)CN suggests that the three methylene units effectively insulate the bipyridyl rings and the rhenium center from the electron-withdrawing effect of the fluorinated alkyl chains. Reductive quenching of the metal-to-ligand charge-transfer excited states with triethylamine reveals quenching rate constants in supercritical CO(2) that are only 6 times slower than those in CH(3)CN.

  9. Electrochemical behaviour of PES ionomer and Pt-free catalyst for PEMFCs

    Directory of Open Access Journals (Sweden)

    STEFANIA GIORDANO

    2013-06-01

    Full Text Available Proton Exchange Membrane Fuel Cells (PEMFCs represent promising technologies to the world economy, with many applications and low environmental impact. A most important aspect concerning their widespread implementation is the cost of polymeric membranes, typically perfluorinated membranes and platinum-based catalytic electrode materials, all of which are necessary to promote electrode reactions, thus increasing fuel cell energy efficiency. In this work, we present some data about non-fluorinated polyetheresulphone (PES membranes and Pt-free catalysts, as possible substitutes of the above materials. Their electrochemical behaviour in oxygen reduction reaction in acidic media are investigated and compared with available reference materials.

  10. Performance comparison of portable direct methanol fuel cell mini-stacks based on a low-cost fluorine-free polymer electrolyte and Nafion membrane

    International Nuclear Information System (INIS)

    Baglio, V.; Stassi, A.; Modica, E.; Antonucci, V.; Arico, A.S.; Caracino, P.; Ballabio, O.; Colombo, M.; Kopnin, E.

    2010-01-01

    A low-cost fluorine-free proton conducting polymer electrolyte was investigated for application in direct methanol fuel cell (DMFC) mini-stacks. The membrane consisted of a sulfonated polystyrene grafted onto a polyethylene backbone. DMFC operating conditions specifically addressing portable applications, i.e. passive mode, air breathing, high methanol concentration, room temperature, were selected. The device consisted of a passive DMFC monopolar three-cell stack. Two designs for flow-fields/current collectors based on open-flow or grid-like geometry were investigated. An optimization of the mini-stack structure was necessary to improve utilization of the fluorine-free membrane. Titanium-grid current collectors with proper mechanical stiffness allowed a significant increase of the performance by reducing contact resistance even in the case of significant swelling. A single cell maximum power density of about 18 mW cm -2 was achieved with the fluorine-free membrane at room temperature under passive mode. As a comparison, the performance obtained with Nafion 117 membrane and Ti grids was 31 mW cm -2 . Despite the lower performance, the fluorine-free membrane showed good characteristics for application in portable DMFCs especially with regard to the perspectives of significant cost reduction.

  11. Electrochemical energy storage

    CERN Document Server

    Tarascon, Jean-Marie

    2015-01-01

    The electrochemical storage of energy has become essential in assisting the development of electrical transport and use of renewable energies. French researchers have played a key role in this domain but Asia is currently the market leader. Not wanting to see history repeat itself, France created the research network on electrochemical energy storage (RS2E) in 2011. This book discusses the launch of RS2E, its stakeholders, objectives, and integrated structure that assures a continuum between basic research, technological research and industries. Here, the authors will cover the technological

  12. Electrochemical Hydrogen Evolution

    DEFF Research Database (Denmark)

    Laursen, A.B.; Varela Gasque, Ana Sofia; Dionigi, F.

    2012-01-01

    The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing new, inexpensive, and abundant HER catalysts is important. Here, we describe how a simple experiment...... catalysts based on this. Suited for upper-level high school and first-year university students, this exercise involves using a basic two-cell electrochemical setup to test multiple electrode materials as catalysts at one applied potential, and then constructing a volcano curve with the resulting currents...

  13. 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.

  14. Fabrication of superhydrophobic fluorinated silica nanoparticles for multifunctional liquid marbles

    Science.gov (United States)

    Shang, Qianqian; Hu, Lihong; Hu, Yun; Liu, Chengguo; Zhou, Yonghong

    2018-01-01

    A facile one-pot method for the fabrication of superhydrophobic fluorinated silica nanoparticles is reported. Fluorinated aggregated silica (A-SiO2/FAS) nanoparticles were synthesized by controlling the nanoparticles assembly, in situ fixation and overgrowth of particle seeds with the assist of tetraethoxysilane (TEOS) in ethanol/water solution and then modification with fluoroalkylsilane (FAS) molecules. Such kind of A-SiO2/FAS nanoparticles showed superhydrophobicity and was not wetted by water, thus it could be served as the encapsulating shells to manipulate liquid droplets. Liquid marbles fabricated from A-SiO2/FAS nanoparticles were used for ammonia gas sensing or emitting by taking advantage of the porosity and superhydrophobicity of the liquid marble shells. In addition, the posibility of A-SiO2/FAS-based liquid marbles as microreactor for dopamine polymerization also was explored.

  15. 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.

  16. 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.

  17. 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

  18. Fluorinated monovacancies in graphene: Even-odd effect

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-11-01

    The electronic and structural properties of fluorinated monovacancies in graphene are studied using density functional theory. Our calculations show that an odd number of F atoms adsorbed on a monovacancy gives rise to a p-type metallic state with a local magnetic moment of 1μ B. In contrast, an even number of F atoms leads to a non-magnetic semiconducting state. We explain the behaviour in terms of local structure properties. © Copyright EPLA, 2012.

  19. Fluorinated analogs of malachite green: synthesis and toxicity.

    Science.gov (United States)

    Kraus, George A; Jeon, Insik; Nilsen-Hamilton, Marit; Awad, Ahmed M; Banerjee, Jayeeta; Parvin, Bahram

    2008-04-27

    A series of fluorinated analogs of malachite green (MG) have been synthesized and their toxicity to Saccharomyces cerevisiae and a human ovarian epithelial cell line examined. The toxicity profiles were found to be different for these two species. Two analogs, one with 2,4-difluoro substitution and the other with 2-fluoro substitution seem to be the most promising analogs because they showed the lowest toxicity to the human cells.

  20. Fluorinated monovacancies in graphene: Even-odd effect

    KAUST Repository

    Kaloni, Thaneshwor P.; Cheng, Yingchun; Schwingenschlö gl, Udo

    2012-01-01

    The electronic and structural properties of fluorinated monovacancies in graphene are studied using density functional theory. Our calculations show that an odd number of F atoms adsorbed on a monovacancy gives rise to a p-type metallic state with a local magnetic moment of 1μ B. In contrast, an even number of F atoms leads to a non-magnetic semiconducting state. We explain the behaviour in terms of local structure properties. © Copyright EPLA, 2012.

  1. A double-stage pulsed discharge fluorine atom beam source

    International Nuclear Information System (INIS)

    Ren Zefeng; Qiu Minghui; Che Li; Dai Dongxu; Wang Xiuyan; Yang Xueming

    2006-01-01

    Molecular-beam intensity and speed ratio are two major limiting factors in many molecular-beam experiments. This article reports a high-intensity, high-speed-ratio, pulsed supersonic fluorine atom beam source using a double-stage discharge beam source. Its performance is indicated by the high-resolution time-of-flight spectrum in the crossed beam experiment of F( 2 P)+para-H 2

  2. Bibliography about silicon non-organic fluorine compounds

    International Nuclear Information System (INIS)

    Carles, M.

    1963-01-01

    This bibliography is made from Professor I.G. Ryss' book published in Moscow in 1956, translated in English under the title 'The chemistry of fluorine and its inorganic compounds' (Translation series. AEC tr 3927, Pt 1 and 2), and completed with the data found in the 'Chemical Abstracts' of the years 1946 to 1962 [fr

  3. Fluorinated Analogs of Malachite Green: Synthesis and Toxicity

    Directory of Open Access Journals (Sweden)

    Bahram Parvin

    2008-04-01

    Full Text Available A series of fluorinated analogs of malachite green (MG have been synthesizedand their toxicity to Saccharomyces cerevisiae and a human ovarian epithelial cell lineexamined. The toxicity profiles were found to be different for these two species. Twoanalogs, one with 2,4-difluoro substitution and the other with 2-fluoro substitution seem tobe the most promising analogs because they showed the lowest toxicity to the human cells.

  4. Use of ASP for Removal of Fluorine and Ammonium Ions

    International Nuclear Information System (INIS)

    Martin HB, A; Las, T

    1998-01-01

    The purified zeolites from Bayah, Lampung dan Tasik have been modified into microporous alumino-silico phosphate (ASP) which could be used as anion and cation exchangers. ASP has been prepared by mixing purified zeolites and ammonium dihydrogen phosphate in weight ratios of 1 :1, 1 :5 and 5:1. The materials have been characterized by XRF, XRD and TG. The ion-exchange experiments have been performed by batch method for various concentrations of 0.01, 0.04, 0.08, 0.2 and O,4 NF and NH 4 ion. Column experiment has been performed for: 500 ppm of ion F ( 0,026 N) and 100 ppm (0.0055 N) of ion NH 4 concentrations respectively, fed into 1 cm diameter column containing 3 g pure ion exchangers. From batch experiment the fluorine sorption increases following the increase the concentration and F could be adsorbed up to about 1.09 -9.17 eq/kg for in the range of concentration 0.01 - 0.08 N. For higher fluorine concentration, the fluorine sorption tends to fluctuate. The ammonium sorption experiments obtain similar results for purified zeolites and ASP. The ion could be absorbed up to about 1.09 - 14.24 eq/kg. In column experiment, 1 g ASP could absorb fluorine up to about 278,48 - 334,19 BV ( 900-1300 ml) at 50% BT, and absorb NH 4 about 219.64 - 297.17 BV (850 -1150 ml) separately. These result shows that the ASP might be a potential material to be used for removal of ion F and NH 4 from the waste generayed in the fuel element fabrication

  5. Dynamic polarization of 19F in a fluorinated alcohol

    International Nuclear Information System (INIS)

    Hill, D.; Kasprzyk, T.; Jarmer, J.J.; Penttilae, S.; Krumpolc, M.; Hoffmann, G.W.; Purcell, M.

    1988-01-01

    We have studied microwave dynamic cooling of 19 F and 1 H nuclei in mixtures of 1,1,1,3,3,3-hexafluoro-2-propanol and water, doped with Cr(V) complex. Equal spin temperatures of the two nuclei are produced, and the highest spin polarizations (/approximately/80%) are found in mixtures near the eutectic ratio. The high fluorine content and polarization make this a suitable material for polarized nuclear scattering experiments. 11 refs., 3 figs., 1 tab

  6. Nucleophilic tetrafluoroethylation of carbonyl compounds with fluorinated sulfones

    Czech Academy of Sciences Publication Activity Database

    Václavík, Jiří; Chernykh, Yana; Jurásek, Bronislav; Beier, Petr

    2015-01-01

    Roč. 169, Jan (2015), s. 24-31 ISSN 0022-1139 R&D Projects: GA ČR GAP207/11/0421 Grant - others:GA MŠk(CZ) ED3.2.00/08.0144; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388963 Keywords : fluorine * tetrafluoroethylation * sulfones * nucleophilic addition * carbonyl compounds Subject RIV: CC - Organic Chemistry Impact factor: 2.213, year: 2015

  7. Post-modification by γ-radiation of VDF-based polymers: Electrochemical capacitor membrane application

    International Nuclear Information System (INIS)

    Dumas, L.

    2012-01-01

    This work deals with the modification of VDF-based polymer induced by γ-radiation as the polymer may be used in electrochemical super-capacitors. The main objective was to limit the swelling of the fluorinated matrix with a given electrolyte while a good wetting of the polymer by the liquid was also required. As the main basic process involved in polymer radiolysis is the formation of radicals, a part of the work was dedicated to the study of such species by using Electron Spin Resonance spectroscopy. A simulation model of ESR spectra was established in order to identify and quantify each radical species. The effect of several parameters such as radiation dose, annealing time or the nature of polymer matrix on the concentration of each species where investigated. A relation with the evolution of the crosslink density of the network formed during the radiolysis was proposed. In addition, one of the key steps of this work was to study the radiation crosslinking ability of VDF-based polymers and find a way to increase the crosslink density. This was achieved by incorporating, prior to the radiation process, a radiation sensitive cross linker: TAIC. Finally, a new strategy based on the modification of surface properties of PVDF was investigated. It consists in the radiation grafting of penta-fluor-styrene onto PVDF surface followed by the chemo-selective functionalization of the grafted segments. As a conclusion, the different approaches used in this thesis allowed us to understand the radiolysis of VDF-based polymers and take advantage of the elementary process involved in this type of chemistry, to build up robust and promising strategies for tuning properties. (author)

  8. Modeling Insight into Battery Electrolyte Electrochemical Stability and Interfacial Structure.

    Science.gov (United States)

    Borodin, Oleg; Ren, Xiaoming; Vatamanu, Jenel; von Wald Cresce, Arthur; Knap, Jaroslaw; Xu, Kang

    2017-12-19

    Electroactive interfaces distinguish electrochemistry from chemistry and enable electrochemical energy devices like batteries, fuel cells, and electric double layer capacitors. In batteries, electrolytes should be either thermodynamically stable at the electrode interfaces or kinetically stable by forming an electronically insulating but ionically conducting interphase. In addition to a traditional optimization of electrolytes by adding cosolvents and sacrificial additives to preferentially reduce or oxidize at the electrode surfaces, knowledge of the local electrolyte composition and structure within the double layer as a function of voltage constitutes the basis of manipulating an interphase and expanding the operating windows of electrochemical devices. In this work, we focus on how the molecular-scale insight into the solvent and ion partitioning in the electrolyte double layer as a function of applied potential could predict changes in electrolyte stability and its initial oxidation and reduction reactions. In molecular dynamics (MD) simulations, highly concentrated lithium aqueous and nonaqueous electrolytes were found to exclude the solvent molecules from directly interacting with the positive electrode surface, which provides an additional mechanism for extending the electrolyte oxidation stability in addition to the well-established simple elimination of "free" solvent at high salt concentrations. We demonstrate that depending on their chemical structures, the anions could be designed to preferentially adsorb or desorb from the positive electrode with increasing electrode potential. This provides additional leverage to dictate the order of anion oxidation and to effectively select a sacrificial anion for decomposition. The opposite electrosorption behaviors of bis(trifluoromethane)sulfonimide (TFSI) and trifluoromethanesulfonate (OTF) as predicted by MD simulation in highly concentrated aqueous electrolytes were confirmed by surface enhanced infrared

  9. Dipolar rotors orderly aligned in mesoporous fluorinated organosilica architectures

    KAUST Repository

    Bracco, Silvia; Beretta, Mario; Cattaneo, Alice Silvia; Comotti, Angiolina; Falqui, Andrea; Zhao, Ke; Rogers, Charles T.; Sozzani, Piero

    2015-01-01

    New mesoporous covalent frameworks, based on hybrid fluorinated organosilicas, were prepared to realize a periodic architecture of fast molecular rotors containing dynamic dipoles in their structure. The mobile elements, designed on the basis of fluorinated p-divinylbenzene moieties, were integrated into the robust covalent structure through siloxane bonds, and showed not only the rapid dynamics of the aromatic rings (ca. 108 Hz at 325 K), as detected by solid-state NMR spectroscopy, but also a dielectric response typical of a fast dipole reorientation under the stimuli of an applied electric field. Furthermore, the mesochannels are open and accessible to diffusing in gas molecules, and rotor mobility could be individually regulated by I2 vapors. The iodine enters the channels of the periodic structure and reacts with the pivotal double bonds of the divinyl-fluoro-phenylene rotors, affecting their motion and the dielectric properties. Oriented molecular rotors: Fluorinated molecular rotors (see picture) were engineered in mesoporous hybrid organosilica architectures with crystalline order in their walls. The rotor dynamics was established by magic angle spinning NMR and dielectric measurements, indicating a rotational correlation time as short as 10-9 s at 325 K. The dynamics was modulated by I2 vapors entering the pores.

  10. Fluorinated graphene films with graphene quantum dots for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Antonova, I. V., E-mail: antonova@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, Russian Academy of Sciences, Siberian Branch, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Nebogatikova, N. A.; Prinz, V. Ya. [Rzhanov Institute of Semiconductor Physics, Russian Academy of Sciences, Siberian Branch, Novosibirsk 630090 (Russian Federation)

    2016-06-14

    This work analyzes carrier transport, the relaxation of non-equilibrium charge, and the electronic structure of fluorinated graphene (FG) films with graphene quantum dots (GQDs). The FG films with GQDs were fabricated by means of chemical functionalization in an aqueous solution of hydrofluoric acid. High fluctuations of potential relief inside the FG barriers have been detected in the range of up to 200 mV. A phenomenological expression that describes the dependence of the time of non-equilibrium charge emission from GQDs on quantum confinement levels and film thickness (potential barrier parameters between GQDs) is suggested. An increase in the degree of functionalization leads to a decrease in GQD size, the removal of the GQD effect on carrier transport, and the relaxation of non-equilibrium charge. The study of the electronic properties of FG films with GQDs has revealed a unipolar resistive switching effect in the films with a relatively high degree of fluorination and a high current modulation (up to ON/OFF ∼ 10{sup 4}–10{sup 5}) in transistor-like structures with a lower degree of fluorination. 2D films with GQDs are believed to have considerable potential for various electronic applications (nonvolatile memory, 2D connections with optical control and logic elements).

  11. Hydrogen and fluorine in the surfaces of lunar samples

    International Nuclear Information System (INIS)

    Leich, D.A.; Goldberg, R.H.; Burnett, D.S.; Tombrello, T.A.

    1974-04-01

    The resonant nuclear reaction F-19 (p, alpha gamma)O-16 was used to perform depth sensitive analyses for both fluorine and hydrogen in lunar samples. The resonance at 0.83 MeV (center-of-mass) in this reaction was applied to the measurement of the distribution of trapped solar protons in lunar samples to depths of about 1 / 2 micrometer. These results are interpreted in terms of terrestrial H 2 O surface contamination and a redistribution of the implanted solar H which has been influenced by heavy radiation damage in the surface region. Results are also presented for an experiment to test the penetration of H 2 O into laboratory glass samples which have been irradiated with O-16 to simulate the radiation damaged surfaces of lunar glasses. Fluorine determinations were performed in a 1 pm surface layer on lunar samples using the same F-19(alpha gamma)O-16 resonance. The data are discussed from the standpoint of lunar fluorine and Teflon contamination. (U.S.)

  12. 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

  13. 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)

  14. 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)

  15. Dipolar rotors orderly aligned in mesoporous fluorinated organosilica architectures

    KAUST Repository

    Bracco, Silvia

    2015-02-16

    New mesoporous covalent frameworks, based on hybrid fluorinated organosilicas, were prepared to realize a periodic architecture of fast molecular rotors containing dynamic dipoles in their structure. The mobile elements, designed on the basis of fluorinated p-divinylbenzene moieties, were integrated into the robust covalent structure through siloxane bonds, and showed not only the rapid dynamics of the aromatic rings (ca. 108 Hz at 325 K), as detected by solid-state NMR spectroscopy, but also a dielectric response typical of a fast dipole reorientation under the stimuli of an applied electric field. Furthermore, the mesochannels are open and accessible to diffusing in gas molecules, and rotor mobility could be individually regulated by I2 vapors. The iodine enters the channels of the periodic structure and reacts with the pivotal double bonds of the divinyl-fluoro-phenylene rotors, affecting their motion and the dielectric properties. Oriented molecular rotors: Fluorinated molecular rotors (see picture) were engineered in mesoporous hybrid organosilica architectures with crystalline order in their walls. The rotor dynamics was established by magic angle spinning NMR and dielectric measurements, indicating a rotational correlation time as short as 10-9 s at 325 K. The dynamics was modulated by I2 vapors entering the pores.

  16. 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.

  17. 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

  18. 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)

  19. Development of Fluorinated Non-Peptidic Ghrelin Receptor Ligands for Potential Use in Molecular Imaging

    Directory of Open Access Journals (Sweden)

    Rareş-Petru Moldovan

    2017-04-01

    Full Text Available The ghrelin receptor (GhrR is a widely investigated target in several diseases. However, the current knowledge of its role and distribution in the brain is limited. Recently, the small and non-peptidic compound (S-6-(4-bromo-2-fluorophenoxy-3-((1-isopropylpiperidin-3-ylmethyl-2-methylpyrido[3,2-d]pyrimidin-4(3H-one ((S-9 has been described as a GhrR ligand with high binding affinity. Here, we describe the synthesis of fluorinated derivatives, the in vitro evaluation of their potency as partial agonists and selectivity at GhrRs, and their physicochemical properties. These results identified compounds (S-9, (R-9, and (S-16 as suitable parent molecules for 18F-labeled positron emission tomography (PET radiotracers to enable future investigation of GhrR in the brain.

  20. 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.

  1. 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.

  2. 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.

  3. Electrochemical Power Sources

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 7. Electrochemical Power Sources - Rechargeable Batteries. A K Shukla S K Martha. General Article Volume 6 Issue 7 July 2001 pp 52-63. Fulltext. Click here to view fulltext PDF. Permanent link:

  4. Electro-chemical grinding

    Science.gov (United States)

    Feagans, P. L.

    1972-01-01

    Electro-chemical grinding technique has rotation speed control, constant feed rates, and contour control. Hypersonic engine parts of nickel alloys can be almost 100% machined, keeping tool pressure at virtual zero. Technique eliminates galling and permits constant surface finish and burr-free interrupted cutting.

  5. Aerobic and Electrochemical Oxidations with N-Oxyl Reagents

    Science.gov (United States)

    Miles, Kelsey C.

    Selective oxidation of organic compounds represents a significant challenge for chemical transformations. Oxidation methods that utilize nitroxyl catalysts have become increasingly attractive and include Cu/nitroxyl and nitroxyl/NO x co-catalyst systems. Electrochemical activation of nitroxyls is also well known and offers an appealing alternative to the use of chemical co-oxidants. However, academic and industrial organic synthetic communities have not widely adopted electrochemical methods. Nitroxyl catalysts facilitate effective and selective oxidation of alcohols and aldehydes to ketones and carboxylic acids. Selective benzylic, allylic, and alpha-heteroatom C-H abstraction can also be achieved with nitroxyls and provides access to oxygenated products when used in combination with molecular oxygen as a radical trap. This thesis reports various chemical and electrochemical oxidation methods that were developed using nitroxyl mediators. Chapter 1 provides a short review on practical aerobic alcohol oxidation with Cu/nitroxyl and nitroxyl/NO x systems and emphasizes the utility of bicyclic nitroxyls as co-catalysts. In Chapter 2, the combination of these bicyclic nitroxyls with NOx is explored for development of a mild oxidation of alpha-chiral aryl aldehydes and showcases a sequential asymmetric hydroformylation/oxidation method. Chapter 3 reports the synthesis and characterization of two novel Cu/bicyclic nitroxyl complexes and the electronic structure analysis of these complexes. Chapter 4 highlights the electrochemical activation of various nitroxyls and reports an in-depth study on electrochemical alcohol oxidation and compares the reactivity of nitroxyls under electrochemical or chemical activation. N-oxyls can also participate in selective C-H abstraction, and Chapter 5 reports the chemical and electrochemical activation of N-oxyls for radical-mediated C-H oxygenation of (hetero)arylmethanes. For these electrochemical transformations, the development of

  6. 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

  7. 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.

  8. Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization.

    Science.gov (United States)

    Struzzi, Claudia; Scardamaglia, Mattia; Colomer, Jean-François; Verdini, Alberto; Floreano, Luca; Snyders, Rony; Bittencourt, Carla

    2017-01-01

    The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT) is correlated to the CF 4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region) on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions.

  9. Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization

    Directory of Open Access Journals (Sweden)

    Claudia Struzzi

    2017-08-01

    Full Text Available The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT is correlated to the CF4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions.

  10. 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.

  11. 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

  12. 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.

  13. Controlled synthesis and electrochemical properties of vanadium ...

    Indian Academy of Sciences (India)

    Vanadium oxides (V3O7·H2O and VO2) with different morphologies have been selectively synthesized ... appeared at around 68 ◦C. Furthermore, the electrochemical properties of V3O7·H2O nanobelts, VO2(B) .... morphologies of shape-controlled orthorhombic V3O7·H2O ..... condition, as shown in figures S14i and j.

  14. 18F fluorination using macrocyclic polyethers

    International Nuclear Information System (INIS)

    Klatte, B.; Knoechel, A.

    The aim of this work is the nucleophilic substitution labelling with 18 F with high selectivity and yield for a short reaction time. Labelling with little or no carrier presumes that 18 F is obtained in anhydrons form. Starting with the production via the nuclear reaction 20 Ne(d,α) 18 F, the 18 F formed is to be continuously converted into an alkali polyether complex whose purpose is to increase the reactivity of the fluoride (compared to the non-complexed anion form), so that nucleophilic substitution reactions can be carried out faster and more carefully. A report is given on the working program and on first results to optimize the carrier-poor synthesis with polyethers as synthesis agent. (RB) [de

  15. 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.

  16. Development and optimization of methods for the radiofluorination of aromatic compounds with specific, high fluorine-18 activity

    International Nuclear Information System (INIS)

    Franken, K.

    1987-06-01

    The positron emitter fluorine-18 (T 1/2 = 110 min) is an ideal radionuclide for analogue tracers in positron emission tomography (PET). In this study the production of the electrophilic species [ 18 F]-F 2 , [ 18 F]-CH 3 CO 2 F and to some extent [ 18 F]-XeF 2 has been optimized with respect to yield and specific activity. Selectivity and reactivity of these species have been studied in simple aromatic model compounds. Fluorine was produced via the 20 Ne(d,α) 18 F reaction. The effect of target material, dimensions, amount of carrier (F 2 ), pressure, beam current and irradiation time was studied. Reactivity of [ 18 F]-F 2 and [ 18 F]-CH 3 CO 2 F with respect to hydrogen subsitution was systematically studied in a series of benzene derivatives (C 6 H 5 X, X = CF 3 , I, Br, CL, F, H, CH 3 , OCH 3 , OH) in various solvents (CHCl 3 , CFCl 3 , CH 3 CN, CH 3 OH, CF 3 COOH). The radiochemical yield of 18 F-for-H-substitution in the aromatic ring increased with increasing acceptor number (AN) of the solvent. The electrophilic nature of both fluorination agents was confirmed by a Hammett plot. As expected, [ 18 F]-CH 3 CO 2 F showed a higher selectivity than [ 18 F]-F 2 . Direct radiofluorination with [ 18 F]-F 2 and [ 18 F]-CH 3 CO 2 F was successfully applied to the biomolecules phenylalanine, tyrosine and DOPA. As potential methods for no-carrier-added (n.c.a.) radiofluorination some less common dediazoniation reactions were also studied. (orig./RB) [de

  17. Low-cost electrochemical treatment of indium tin oxide anodes for high-efficiency organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Hui Cheng, Chuan, E-mail: chengchuanhui@dlut.edu.cn; Shan Liang, Ze; Gang Wang, Li; Dong Gao, Guo; Zhou, Ting; Ming Bian, Ji; Min Luo, Ying [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Tong Du, Guo, E-mail: dugt@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

    2014-01-27

    We demonstrate a simple low-cost approach as an alternative to conventional O{sub 2} plasma treatment to modify the surface of indium tin oxide (ITO) anodes for use in organic light-emitting diodes. ITO is functionalized with F{sup −} ions by electrochemical treatment in dilute hydrofluoric acid. An electrode with a work function of 5.2 eV is achieved following fluorination. Using this electrode, a maximum external quantum efficiency of 26.0% (91 cd/A, 102 lm/W) is obtained, which is 12% higher than that of a device using the O{sub 2} plasma-treated ITO. Fluorination also increases the transparency in the near-infrared region.

  18. 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.

  19. 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.

  20. Characteristics of F doped PZT ceramics using different fluorine sources

    Energy Technology Data Exchange (ETDEWEB)

    Guiffard, B. [Laboratory of Electrical Engineering and Ferroelectricity, LGEF INSA-Lyon, Bat. Gustave Ferrie, 8 rue de la Physique, F-69621 Villeurbanne Cedex (France)]. E-mail: benoit.guiffard@insa-lyon.fr; Boucher, E. [SPCTS, UMR 6638, Faculte des Sciences et Techniques, Universite de Limoges, 123 Avenue Albert Thomas, 87060 Limoges Cedex (France); Lebrun, L. [Laboratory of Electrical Engineering and Ferroelectricity, LGEF INSA-Lyon, Bat. Gustave Ferrie, 8 rue de la Physique, F-69621 Villeurbanne Cedex (France); Guyomar, D. [Laboratory of Electrical Engineering and Ferroelectricity, LGEF INSA-Lyon, Bat. Gustave Ferrie, 8 rue de la Physique, F-69621 Villeurbanne Cedex (France)

    2007-02-25

    In this study, some structural and electrical properties of a PZT base composition Pb{sub 0.89}(Ba, Sr){sub 0.11}(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} co-doped with 1 mol% manganese and 2 mol% fluorine have been studied. Two different fluorine sources were used: lead fluoride PbF{sub 2} and manganese fluoride MnF{sub 2}. These fluoride salts are added to the co-precipitated precursors powder. Mn dopant was added to the solution as manganese acetate (MnAc) before co-precipitation, when PbF{sub 2} was used. The structural analysis of the sintered ceramics revealed that MnF{sub 2} doping makes the volume of the cubic unit cell (V {sub c}) and the grain size decrease, whereas (MnAc, PbF{sub 2}) co-doping makes the apparent density increase and keeps the average grain size and V {sub c} unchanged. Both types of doping reagents largely enhance the piezoelectric activity (high d {sub 33} and k {sub 33} coefficients, well saturated Polarization-Electric field loops) but MnF{sub 2} induces both combinatory soft and hard characteristics compared to (MnAc, PbF{sub 2}) co-doping. Impedance spectroscopy showed that both types of doping reagents strongly reduce the electrical conductivity with the same conducting species, i.e. the same defect chemistry, confirmed by optical absorption data. Finally, this study shows that in the semi-wet process used, PbF{sub 2} is added homogeneously to the co-precipitated powder. Whatever the fluorine source, only the coexistence of Mn and F dopants is necessary to improve the piezoelectric response.

  1. Electrochemical Biosensors - Sensor Principles and Architectures

    Science.gov (United States)

    Grieshaber, Dorothee; MacKenzie, Robert; Vörös, Janos; Reimhult, Erik

    2008-01-01

    Quantification of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. However, converting the biological information to an easily processed electronic signal is challenging due to the complexity of connecting an electronic device directly to a biological environment. Electrochemical biosensors provide an attractive means to analyze the content of a biological sample due to the direct conversion of a biological event to an electronic signal. Over the past decades several sensing concepts and related devices have been developed. In this review, the most common traditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry, impedance spectroscopy, and various field-effect transistor based methods are presented along with selected promising novel approaches, such as nanowire or magnetic nanoparticle-based biosensing. Additional measurement techniques, which have been shown useful in combination with electrochemical detection, are also summarized, such as the electrochemical versions of surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry, quartz crystal microbalance, and scanning probe microscopy. The signal transduction and the general performance of electrochemical sensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches, such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymes into vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities for signal amplification. In particular, this review highlights the importance of the precise control over the delicate

  2. Fluorinated graphenes as advanced biosensors - effect of fluorine coverage on electron transfer properties and adsorption of biomolecules

    Czech Academy of Sciences Publication Activity Database

    Urbanová, V.; Karlický, F.; Matěj, A.; Šembera, Filip; Janoušek, Zbyněk; Perman, J. A.; Ranc, V.; Čépe, K.; Michl, Josef; Otyepka, M.; Zbořil, R.

    2016-01-01

    Roč. 8, č. 24 (2016), s. 12134-12142 ISSN 2040-3364 Institutional support: RVO:61388963 Keywords : functionalized graphene * doped graphene * electrochemical properties Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 7.367, year: 2016

  3. 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.

  4. Oral frostbite injury from intentional abuse of a fluorinated hydrocarbon.

    Science.gov (United States)

    Kuspis, D A; Krenzelok, E P

    1999-01-01

    A serious but rarely reported complication of halogenated hydrocarbon inhalation abuse is severe mucosal frostbite. A 16-year-old male attempted to "get high" by inhaling airbrush propellant which contained 1,1-difluoroethane (CAS #75-376). The patient lost consciousness and upon awakening his lips and tongue were frozen. He suffered first- and second-degree burns of the larynx with vocal cord involvement and first-degree burns of the trachea, main stem bronchi, and esophagus. The oral cavity had second- and third-degree burns which required debridement. This case demonstrates the unusual but severe damage that can occur with the abuse of fluorinated hydrocarbons.

  5. Integrated Photonic Devices Incorporating Low-Loss Fluorinated Polymer Materials

    Directory of Open Access Journals (Sweden)

    Hyung-Jong Lee

    2011-06-01

    Full Text Available Low-loss polymer materials incorporating fluorinated compounds have been utilized for the investigation of various functional optical devices useful for optical communication and optical sensor systems. Since reliability issues concerning the polymer device have been resolved, polymeric waveguide devices have been gradually adopted for commercial application systems. The two most successfully commercialized polymeric integrated optic devices, variable optical attenuators and digital optical switches, are reviewed in this paper. Utilizing unique properties of optical polymers which are not available in other optical materials, novel polymeric optical devices are proposed including widely tunable external cavity lasers and integrated optical current sensors.

  6. Reversibility of Graphene-Enhanced Raman Scattering with Fluorinated Graphene

    Czech Academy of Sciences Publication Activity Database

    Valeš, Václav; Melníková Komínková, Zuzana; Verhagen, Timotheus; Vejpravová, Jana; Kalbáč, Martin

    2017-01-01

    Roč. 254, č. 11 (2017), č. článku 1700177. ISSN 0370-1972 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk(CZ) LM2015073 Grant - others:GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : fluorination * graphene * graphene-enhanced Raman * Raman spectroscopy * scattering Subject RIV: CF - Physical ; Theoretical Chemistry; BM - Solid Matter Physics ; Magnetism (FZU-D) OBOR OECD: Physical chemistry; Condensed matter physics (including formerly solid state physics, supercond.) (FZU-D) Impact factor: 1.674, year: 2016

  7. Fluorine-18 NaF PET imaging of child abuse

    Energy Technology Data Exchange (ETDEWEB)

    Drubach, Laura A. [Children' s Hospital Boston and Harvard Medical School, Department of Radiology, Division of Nuclear Medicine/PET, Boston, MA (United States); Sapp, Mark.V. [School of Osteopathic Medicine, Child Abuse Research Education and Services (CARES) Institute University of Medicine and Dentistry of New Jersey, New Jersey (United States); Laffin, Stephen [Children' s Hospital Boston, Department of Radiology, Division of Nuclear Medicine/PET, Boston, MA (United States); Kleinman, Paul K. [Children' s Hospital Boston and Harvard Medical School, Department of Radiology, Division of Musculoskeletal Imaging, Boston, MA (United States)

    2008-07-15

    We describe the use of {sup 18}F-NaF positron emission tomography (PET) whole-body imaging for the evaluation of skeletal trauma in a case of suspected child abuse. To our knowledge, 18F NaF PET has not been used in the past for the evaluation of child abuse. In our patient, this technique detected all sites of trauma shown by initial and follow-up skeletal surveys, including bilateral metaphyseal fractures of the proximal humeri. Fluorine-18 NaF PET has potential advantage over Tc-99m-labeled methylene diphosphonate (MDP) based upon superior image contrast and spatial resolution. (orig.)

  8. Fluorine-18 NaF PET imaging of child abuse

    International Nuclear Information System (INIS)

    Drubach, Laura A.; Sapp, Mark V.; Laffin, Stephen; Kleinman, Paul K.

    2008-01-01

    We describe the use of 18 F-NaF positron emission tomography (PET) whole-body imaging for the evaluation of skeletal trauma in a case of suspected child abuse. To our knowledge, 18F NaF PET has not been used in the past for the evaluation of child abuse. In our patient, this technique detected all sites of trauma shown by initial and follow-up skeletal surveys, including bilateral metaphyseal fractures of the proximal humeri. Fluorine-18 NaF PET has potential advantage over Tc-99m-labeled methylene diphosphonate (MDP) based upon superior image contrast and spatial resolution. (orig.)

  9. 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)

  10. 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

  11. 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.

  12. 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.

  13. Air pollution by fluorine in Poland and its toxic effect on humans, animals and plants

    Energy Technology Data Exchange (ETDEWEB)

    Paluch, J.; Schalenkowa, I.

    1970-01-01

    The accumulation and distribution of fluorine compounds in plants and animals in the vicinity of emitters of fluorine are reported. The sensitivity and the differences in the accumulating capacity of various plants and animals are discussed. The significance of the problems for the human population is pointed out.

  14. 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

  15. 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.

  16. Catalytic stereoselective synthesis of highly substituted indanones via tandem Nazarov cyclization and electrophilic fluorination trapping.

    Science.gov (United States)

    Nie, Jing; Zhu, Hong-Wei; Cui, Han-Feng; Hua, Ming-Qing; Ma, Jun-An

    2007-08-02

    A new catalytic stereoselective tandem transformation via Nazarov cyclization/electrophilic fluorination has been accomplished. This sequence is efficiently catalyzed by a Cu(II) complex to afford fluorine-containing 1-indanone derivatives with two new stereocenters with high diastereoselectivity (trans/cis up to 49/1). Three examples of catalytic enantioselective tandem transformation are presented.

  17. 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...

  18. Partially fluorinated arylene polyethers and their ternary blend membranes with PBI and H3PO4

    DEFF Research Database (Denmark)

    Kerres, J.; Schonberger, F.; Chromik, A

    2008-01-01

    A partially fluorinated polyether ionomer from polycondensation of decafluorobiphenyl with 2,2-bis(4-hydroxyphenyl)-hexafluoropropane, followed by sulphonation with H2SO4 (60% SO3), has been prepared and optimised in terms of molecular weight and sulphonation degree. The partially fluorinated ion...

  19. Synthesis of no-carrier-added fluorine-18 2-fluoro-2-deoxy-d-glucose

    International Nuclear Information System (INIS)

    Tewson, T.J.

    1983-01-01

    A new synthetic procedure for the preparation of fluorine-18 2-fluoro-2-deoxy-glucose has been developed. This procedure offers the advantages of flexibility in the source of the fluorine-18, high yields, and short synthesis times. The procedure works at the no-carrier-added level and gives a product of very high specific activity

  20. 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.

  1. 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%

  2. Fluoroacetate-mediated toxicity of fluorinated ethanes.

    Science.gov (United States)

    Keller, D A; Roe, D C; Lieder, P H

    1996-04-01

    A series of 1-(di)halo-2-fluoroethanes reported in the literature to be nontoxic or of low toxicity were found to be highly toxic by the inhalation route. Experiments were performed that showed the compounds, 1,2-difluoroethane, 1-chloro-2-fluoroethane, 1-chloro-1,2-difluoroethane, and 1-bromo-2-fluoroethane to be highly toxic to rats upon inhalation for 4 hr. All four compounds had 4-hr approximate lethal concentrations of difluoroethane (commonly referred to as HFC-152a) has very low acute toxicity with a 4-hr LC50 of > 400,000 ppm in rats. Rats exposed to the selected toxic fluoroethanes showed clinical signs of fluoroacetate toxicity (lethargy, hunched posture, convulsions). 1,2-Difluoroethane, 1-chloro-2-fluoroethane, 1-chloro-1,2-difluoroethane, and 1-bromo-2-fluoroethane were shown to increase concentrations of citrate in serum and heart tissue, a hallmark of fluoroacetate intoxication. 19F NMR analysis confirmed that fluoroacetate was present in the urine of rats exposed to each toxic compound. Fluorocitrate, a condensation product of fluoroacetate and oxaloacetate, was identified in the kidney of rats exposed to 1,2-difluoroethane. There was a concentration-related elevation of serum and heart citrate in rats exposed to 0-1000 ppm 1,2-fluoroethane. Serum citrate was increased up to 5-fold and heart citrate was increased up to 11-fold over control citrate levels. Metabolism of 1,2-difluoroethane by cytochrome P450 (most likely CYP2E1) is suspected because pretreatment of rats or mice with SKF-525F, disulfiram, or dimethyl sulfoxide prevented or delayed the toxicity observed in rats not pretreated. Experimental evidence indicates that the metabolism of the toxic fluoroethanes is initiated at the carbon-hydrogen bond, with metabolism to fluoroacetate via an aldehyde or an acyl fluoride. The results of these studies show that 1-(di)halo-2-fluoroethanes are highly toxic to rats and should be considered a hazard to humans unless demonstrated otherwise.

  3. Self-formation of a nanonet of fluorinated carbon nanowires on the Si surface by combined etching in fluorine-containing plasma

    Science.gov (United States)

    Amirov, I. I.; Gorlachev, E. S.; Mazaletskiy, L. A.; Izyumov, M. O.; Alov, N. V.

    2018-03-01

    In this work, we report a technique of the self-formation of a nanonet of fluorinated carbon nanowires on the Si surface using a combined etching in fluorine-containing C4F8/Ar and SF6 plasmas. Using scanning electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy, we show that after the etching of Si in the C4F8/Ar plasma, a fluorinated carbon film of nanometer-scale thickness is formed on its surface and its formation accelerates at elevated temperatures. After a subsequent short-term etching in the SF6 plasma, the film is modified into a nanonet of self-formed fluorinated carbon nanowires.

  4. Disease-Related Detection with Electrochemical Biosensors: A Review

    Directory of Open Access Journals (Sweden)

    Ying Huang

    2017-10-01

    Full Text Available Rapid diagnosis of diseases at their initial stage is critical for effective clinical outcomes and promotes general public health. Classical in vitro diagnostics require centralized laboratories, tedious work and large, expensive devices. In recent years, numerous electrochemical biosensors have been developed and proposed for detection of various diseases based on specific biomarkers taking advantage of their features, including sensitivity, selectivity, low cost and rapid response. This article reviews research trends in disease-related detection with electrochemical biosensors. Focus has been placed on the immobilization mechanism of electrochemical biosensors, and the techniques and materials used for the fabrication of biosensors are introduced in details. Various biomolecules used for different diseases have been listed. Besides, the advances and challenges of using electrochemical biosensors for disease-related applications are discussed.

  5. Disease-Related Detection with Electrochemical Biosensors: A Review.

    Science.gov (United States)

    Huang, Ying; Xu, Jin; Liu, Junjie; Wang, Xiangyang; Chen, Bin

    2017-10-17

    Rapid diagnosis of diseases at their initial stage is critical for effective clinical outcomes and promotes general public health. Classical in vitro diagnostics require centralized laboratories, tedious work and large, expensive devices. In recent years, numerous electrochemical biosensors have been developed and proposed for detection of various diseases based on specific biomarkers taking advantage of their features, including sensitivity, selectivity, low cost and rapid response. This article reviews research trends in disease-related detection with electrochemical biosensors. Focus has been placed on the immobilization mechanism of electrochemical biosensors, and the techniques and materials used for the fabrication of biosensors are introduced in details. Various biomolecules used for different diseases have been listed. Besides, the advances and challenges of using electrochemical biosensors for disease-related applications are discussed.

  6. 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

  7. 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

  8. Electrochemical Approaches to Renewable Energy

    Science.gov (United States)

    Lobaccaro, Peter

    chapters 4-6, the electrochemical reduction of carbon dioxide (CO2R) is investigated as this reaction can produce hydrocarbons and alcohols as opposed to just hydrogen. First in chapter 4, the electrochemical cell, which is used to test the activity of CO2R catalysts, is scrutinized. The electrochemical cell is a mini-chemical reactor and it is important to monitor the reaction conditions within the reactor to ensure that they are constant throughout the study. I show that operating cells with high catalyst surface area to electrolyte volume ratios (S/V) at high current densities can have subtle consequences during CO2R, particularly as they relate to the bulk electrolyte CO2 concentration. By using the pH in the cell to measure the CO2 concentration, significant undersaturation of CO2 is observed in the bulk electrolyte, even at modest current densities of 10 mA cm-2. Undersaturation of CO2 produces large changes in the faradaic efficiency observed on copper electrodes, with hydrogen production becoming increasingly favored. Then in chapter 5, the use of selected-ion flow-tube mass spectrometry (SIFT-MS) as an analytical tool to detect the products of CO2R is investigated. The real-time analysis of the products of CO2R is especially of interest to enable the study of how and when the liquid products of the reaction are generated. This is currently only possible in some limited situations and an analytical tool that can do quantitative analysis of all the products of the CO2R reaction in real-time does not exist. I show that SIFT-MS is a promising technique which can uniquely detect the hydrocarbon, alcohols, and aldehydes produced during CO2R on copper. Furthermore, SIFT-MS should be able to provide quantitative results; however, further study is needed to rigorously prove this. Finally in chapter 6, a CO2R catalyst platform is developed based on templated electrochemically deposited nanowires. This platform is used to investigate the role of high surface area in catalyst

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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)

  14. The strategies of DNA immobilization and hybridization detection mechanism in the construction of electrochemical DNA sensor: A review

    Directory of Open Access Journals (Sweden)

    Jahwarhar Izuan Abdul Rashid

    2017-11-01

    Full Text Available In recent years, electrochemical deoxyribonucleic acid (DNA sensor has recently emerged as promising alternative clinical diagnostic devices especially for infectious disease by exploiting DNA recognition events and converting them into an electrochemical signal. This is because the existing DNA diagnostic method possesses certain drawbacks such as time-consuming, expensive, laborious, low selectivity and sensitivity. DNA immobilization strategies and mechanism of electrochemical detection are two the most important aspects that should be considered before developing highly selective and sensitive electrochemical DNA sensor. Here, we focus on some recent strategies for DNA probes immobilization on the surface of electrochemical transducer such as adsorption, covalent bonding and Avidin/Streptavidin-Biotin interaction on the electrode surface for specific interaction with its complementary DNA target. A numerous approach for DNA hybridization detection based electrochemical technique that frequently used including direct DNA electrochemical detection and label based electrochemical (redox-active indicator, enzyme label and nanoparticles were also discussed in aiming to provide general guide for the design of electrochemical DNA sensor. We also discussed the challenges and suggestions to improve the application of electrochemical DNA sensor at point-care setting. Keywords: Electrochemical DNA sensor, DNA immobilization, DNA hybridization, Electrochemical mechanism

  15. Electrochemical characteristics of polyacetylene in organic electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Padula, A.; Scrosati, B.

    1985-01-15

    The characteristics of the electrochemical doping process of polyacetylene have been investigated in lithium cells using lithium perchlorate in propylene carbonate as electrolytic solution. The kinetics of this process are controlled by the diffusion of the dopant species throughout the polymer. Therefore, polyacetylene samples with a highly porous, extended surface should be selected for the development of efficient, rechargeable lithium batteries. In line with this, we have considered foam-type polyacetylene electrodes which have a lower density than the 'classical' Shirakawa-type film electrodes. The electrochemical behaviour of the polyacetylene foam samples has been examined by cyclic voltametry response and constant current, charge-discharge cycles. The results are described in this work.

  16. Recent Progress in Electrochemical Biosensors for Glycoproteins

    Directory of Open Access Journals (Sweden)

    Uichi Akiba

    2016-12-01

    Full Text Available This review provides an overview of recent progress in the development of electrochemical biosensors for glycoproteins. Electrochemical glycoprotein sensors are constructed by combining metal and carbon electrodes with glycoprotein-selective binding elements including antibodies, lectin, phenylboronic acid and molecularly imprinted polymers. A recent trend in the preparation of glycoprotein sensors is the successful use of nanomaterials such as graphene, carbon nanotube, and metal nanoparticles. These nanomaterials are extremely useful for improving the sensitivity of glycoprotein sensors. This review focuses mainly on the protocols for the preparation of glycoprotein sensors and the materials used. Recent improvements in glycoprotein sensors are discussed by grouping the sensors into several categories based on the materials used as recognition elements.

  17. 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.

  18. 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.

  19. Study of sulfonated polyether ether ketone with pendant lithiated fluorinated sulfonic groups as ion conductive binder in lithium-ion batteries

    Science.gov (United States)

    Wei, Zengbin; Xue, Lixin; Nie, Feng; Sheng, Jianfang; Shi, Qianru; Zhao, Xiulan

    2014-06-01

    In an attempt to reduce the Li+ concentration polarization and electrolyte depletion from the electrode porous space, sulfonated polyether ether ketone with pendant lithiated fluorinated sulfonic groups (SPEEK-FSA-Li) is prepared and attempted as ionic conductivity binder. Sulfonated aromatic poly(ether ether ketone) exhibits strong adhesion and chemical stability, and lithiated fluorinated sulfonic side chains help to enhance the ionic conductivity and Li+ ion diffusion due to the charge delocalization over the sulfonic chain. The performances are evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, charge-discharge cycle testing, 180° peel testing, and compared with the cathode prepared with polyvinylidene fluoride binder. The electrode prepared with SPEEK-FSA-Li binder forms the relatively smaller resistances of both the SEI and the charge transfer of lithium ion transport. This is beneficial to lithium ion intercalation and de-intercalation of the cathode during discharging-charging, therefore the cell prepared with SPEEK-FSA-Li shows lower charge plateau potential and higher discharge plateau potential. Compared with PVDF, the electrode with ionic binder shows smaller decrease in capacity with the increasing of cycle rate. Meanwhile, adhesion strength of electrode prepared with SPEEK-FSA-Li is more than five times greater than that with PVDF.

  20. 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.