WorldWideScience

Sample records for surface-initiated living radical

  1. On Surface-Initiated Atom Transfer Radical Polymerization Using Diazonium Chemistry To Introduce the Initiator Layer

    DEFF Research Database (Denmark)

    Iruthayaraj, Joseph; Chernyy, Sergey; Lillethorup, Mie

    2011-01-01

    This work features the controllability of surface-initiated atom transfer radical polymerization (SI-ATRP) of methyl methacrylate, initiated by a multilayered 2-bromoisobutyryl moiety formed via diazonium chemistry. The thickness as a function of polymerization time has been studied by varying di...

  2. Polymer coating comprising 2-methoxyethyl acrylate units synthesized by surface-initiated atom transfer radical polymerization

    DEFF Research Database (Denmark)

    2011-01-01

    Source: US2012184029A The present invention relates to preparation of a polymer coating comprising or consisting of polymer chains comprising or consisting of units of 2-methoxyethyl acrylate synthesized by Surface-Initiated Atom Transfer Radical Polymerization (SI ATRP) such as ARGET SI ATRP...

  3. Functionalized polymer film surfaces via surface-initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Hu, Y.; Li, J.S.; Yang, W.T.; Xu, F.J.

    2013-01-01

    The ability to manipulate and control the surface properties of polymer films, without altering the substrate properties, is crucial to their wide-spread applications. In this work, a simple one-step method for the direct immobilization of benzyl chloride groups (as the effective atom transfer radical polymerization (ATRP) initiators) on the polymer films was developed via benzophenone-induced coupling of 4-vinylbenzyl chloride (VBC). Polyethylene (PE) and nylon films were selected as examples of polymer films to illustrate the functionalization of film surfaces via surface-initiated ATRP. Functional polymer brushes of (2-dimethylamino)ethyl methacrylate, sodium 4-styrenesulfonate, 2-hydroxyethyl methacrylate and glycidyl methacrylate, as well as their block copolymer brushes, have been prepared via surface-initiated ATRP from the VBC-coupled PE or nylon film surfaces. With the development of a simple approach to the covalent immobilization of ATRP initiators on polymer film surfaces and the inherent versatility of surface-initiated ATRP, the surface functionality of polymer films can be precisely tailored. - Highlights: ► Atom transfer radical polymerization initiators were simply immobilized. ► Different functional polymer brushes were readily prepared. ► Their block copolymer brushes were also readily prepared

  4. Hydrophilization of poly(ether ether ketone) films by surface-initiated atom transfer radical polymerization

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Hvilsted, Søren

    2010-01-01

    Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) has been exploited to hydrophilize PEEK. The ketone groups on the PEEK surface were reduced to hydroxyl groups which were converted to bromoisobutyrate initiating sites for SI-ATRP. The modification steps were followed by contact...... angle measurements and XPS. Moreover, ATR FTIR has been used to confirm the formation of initiating groups. Grafting of PEGMA from PEEK was performed in aqueous solution. The presence of the PPEGMA grafts on PEEK was revealed by the thermograms from TGA whereas investigations with AFM rejected changes...

  5. In situ AFM investigation of electrochemically induced surface-initiated atom-transfer radical polymerization.

    Science.gov (United States)

    Li, Bin; Yu, Bo; Zhou, Feng

    2013-02-12

    Electrochemically induced surface-initiated atom-transfer radical polymerization is traced by in situ AFM technology for the first time, which allows visualization of the polymer growth process. It affords a fundamental insight into the surface morphology and growth mechanism simultaneously. Using this technique, the polymerization kinetics of two model monomers were studied, namely the anionic 3-sulfopropyl methacrylate potassium salt (SPMA) and the cationic 2-(metharyloyloxy)ethyltrimethylammonium chloride (METAC). The growth of METAC is significantly improved by screening the ammonium cations by the addition of ionic liquid electrolyte in aqueous solution. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Fabrication of Robust and Antifouling Superhydrophobic Surfaces via Surface-Initiated Atom Transfer Radical Polymerization.

    Science.gov (United States)

    Xue, Chao-Hua; Guo, Xiao-Jing; Ma, Jian-Zhong; Jia, Shun-Tian

    2015-04-22

    Superhydrophobic surfaces were fabricated via surface-initiated atom transfer radical polymerization of fluorinated methacrylates on poly(ethylene terephthalate) (PET) fabrics. The hydrophobicity of the PET fabric was systematically tunable by controlling the polymerization time. The obtained superhydrophobic fabrics showed excellent chemical robustness even after exposure to different chemicals, such as acid, base, salt, acetone, and toluene. Importantly, the fabrics maintained superhydrophobicity after 2500 abrasion cycles, 100 laundering cycles, and long time exposure to UV irradiation. Also, the surface of the superhydrophobic fabrics showed excellent antifouling properties.

  7. In Situ Investigation of Electrochemically Mediated Surface-Initiated Atom Transfer Radical Polymerization by Electrochemical Surface Plasmon Resonance.

    Science.gov (United States)

    Chen, Daqun; Hu, Weihua

    2017-04-18

    Electrochemically mediated atom transfer radical polymerization (eATRP) initiates/controls the controlled/living ATRP chain propagation process by electrochemically generating (regenerating) the activator (lower-oxidation-state metal complex) from deactivator (higher-oxidation-state metal complex). Despite successful demonstrations in both of the homogeneous polymerization and heterogeneous systems (namely, surface-initiated ATRP, SI-ATRP), the eATRP process itself has never been in situ investigated, and important information regarding this process remains unrevealed. In this work, we report the first investigation of the electrochemically mediated SI-ATRP (eSI-ATRP) by rationally combining the electrochemical technique with real-time surface plasmon resonance (SPR). In the experiment, the potential of a SPR gold chip modified by the self-assembled monolayer of the ATRP initiator was controlled to electrochemically reduce the deactivator to activator to initiate the SI-ATRP, and the whole process was simultaneously monitored by SPR with a high time resolution of 0.1 s. It is found that it is feasible to electrochemically trigger/control the SI-ATRP and the polymerization rate is correlated to the potential applied to the gold chip. This work reveals important kinetic information for eSI-ATRP and offers a powerful platform for in situ investigation of such complicated processes.

  8. Surface-Initiated Graft Atom Transfer Radical Polymerization of Methyl Methacrylate from Chitin Nanofiber Macroinitiator under Dispersion Conditions

    Directory of Open Access Journals (Sweden)

    Ryo Endo

    2015-08-01

    Full Text Available Surface-initiated graft atom transfer radical polymerization (ATRP of methyl methacrylate (MMA from self-assembled chitin nanofibers (CNFs was performed under dispersion conditions. Self-assembled CNFs were initially prepared by regeneration from a chitin ion gel with 1-allyl-3-methylimidazolium bromide using methanol; the product was then converted into the chitin nanofiber macroinitiator by reaction with α-bromoisobutyryl bromide in a dispersion containing N,N-dimethylformamide. Surface-initiated graft ATRP of MMA from the initiating sites on the CNFs was subsequently carried out under dispersion conditions, followed by filtration to obtain the CNF-graft-polyMMA film. Analysis of the product confirmed the occurrence of the graft ATRP on the surface of the CNFs.

  9. Surface-initiated Atom Transfer Radical Polymerization - a Technique to Develop Biofunctional Coatings

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Hvilsted, Søren

    2009-01-01

    The initial formation of initiating sites for atom transfer radical polymerization (ATRP) on various polymer surfaces and numerous inorganic and metallic surfaces is elaborated. The subsequent ATRP grafting of a multitude of monomers from such surfaces to generate thin covalently linked polymer...

  10. Visible Light-Induced Metal Free Surface Initiated Atom Transfer Radical Polymerization of Methyl Methacrylate on SBA-15

    Directory of Open Access Journals (Sweden)

    Liang Ma

    2017-02-01

    Full Text Available Surface-initiated atom transfer radical polymerization (SI-ATRP is one of the most versatile techniques to modify the surface properties of materials. Recent developed metal-free SI-ATRP makes such techniques more widely applicable. Herein photo-induced metal-free SI-ATRP of methacrylates, such as methyl methacrylate, N-isopropanyl acrylamide, and N,N-dimethylaminoethyl methacrylate, on the surface of SBA-15 was reported to fabricate organic-inorganic hybrid materials. A SBA-15-based polymeric composite with an adjustable graft ratio was obtained. The structure evolution during the SI-ATRP modification of SBA-15 was monitored and verified by FT-IR, XPS, TGA, BET, and TEM. The obtained polymeric composite showed enhanced adsorption ability for the model compound toluene in aqueous conditions. This procedure provides a low-cost, readily available, and easy modification method to synthesize polymeric composites without the contamination of metal.

  11. Crystalline TiO2 grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom-transfer radical polymerization

    International Nuclear Information System (INIS)

    Zhao Yuancong; Tu Qiufen; Wang Jin; Huang Qiongjian; Huang Nan

    2010-01-01

    Crystalline TiO 2 films were prepared by unbalanced magnetron sputtering and the structure was confirmed by XRD. An organic layer of 11-hydroxyundecylphosphonic acid (HUPA) was prepared on the TiO 2 films by self-assembling, and the HUPA on TiO 2 films was confirmed by FTIR analysis. Simultaneously, hydroxyl groups were introduced in the phosphonic acid molecules to provide a functionality for further chemical modification. 2-Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was chemically grafted on the HUPA surfaces at room temperature by surface-initiated atom-transfer radical polymerization. The surface characters of TiO 2 films modified by poly-MPC were confirmed by FTIR, XPS and SEM analysis. Platelet adhesion experiment revealed that poly-MPC modified surface was effective to inhibit platelet adhesion in vitro.

  12. Crystalline TiO 2 grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom-transfer radical polymerization

    Science.gov (United States)

    Zhao, Yuancong; Tu, Qiufen; Wang, Jin; Huang, Qiongjian; Huang, Nan

    2010-12-01

    Crystalline TiO 2 films were prepared by unbalanced magnetron sputtering and the structure was confirmed by XRD. An organic layer of 11-hydroxyundecylphosphonic acid (HUPA) was prepared on the TiO 2 films by self-assembling, and the HUPA on TiO 2 films was confirmed by FTIR analysis. Simultaneously, hydroxyl groups were introduced in the phosphonic acid molecules to provide a functionality for further chemical modification. 2-Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was chemically grafted on the HUPA surfaces at room temperature by surface-initiated atom-transfer radical polymerization. The surface characters of TiO 2 films modified by poly-MPC were confirmed by FTIR, XPS and SEM analysis. Platelet adhesion experiment revealed that poly-MPC modified surface was effective to inhibit platelet adhesion in vitro.

  13. Surface PEGylation of mesoporous silica materials via surface-initiated chain transfer free radical polymerization: Characterization and controlled drug release.

    Science.gov (United States)

    Huang, Long; Liu, Meiying; Mao, Liucheng; Huang, Qiang; Huang, Hongye; Wan, Qing; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

    2017-12-01

    As a new type of mesoporous silica materials with large pore diameter (pore size between 2 and 50nm) and high specific surface areas, SBA-15 has been widely explored for different applications especially in the biomedical fields. The surface modification of SBA-15 with functional polymers has demonstrated to be an effective way for improving its properties and performance. In this work, we reported the preparation of PEGylated SBA-15 polymer composites through surface-initiated chain transfer free radical polymerization for the first time. The thiol group was first introduced on SBA-15 via co-condensation with γ-mercaptopropyltrimethoxysilane (MPTS), that were utilized to initiate the chain transfer free radical polymerization using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and itaconic acid (IA) as the monomers. The successful modification of SBA-15 with poly(PEGMA-co-IA) copolymers was evidenced by a series of characterization techniques, including 1 H NMR, FT-IR, TGA and XPS. The final SBA-15-SH- poly(PEGMA-co-IA) composites display well water dispersity and high loading capability towards cisplatin (CDDP) owing to the introduction of hydrophilic PEGMA and carboxyl groups. Furthermore, the CDDP could be released from SBA-15-SH-poly(PEGMA-co-IA)-CDDP complexes in a pH dependent behavior, suggesting the potential controlled drug delivery of SBA-15-SH-poly(PEGMA-co-IA). More importantly, the strategy should be also useful for fabrication of many other functional materials for biomedical applications owing to the advantages of SBA-15 and well monomer adoptability of chain transfer free radical polymerization. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Hydrogel brushes grafted from stainless steel via surface-initiated atom transfer radical polymerization for marine antifouling

    Science.gov (United States)

    Wang, Jingjing; Wei, Jun

    2016-09-01

    Crosslinked hydrogel brushes were grafted from stainless steel (SS) surfaces for marine antifouling. The brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) respectively with different fractions of crosslinker in the feed. The grafted layers prepared with different thickness were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ellipsometry and water contact angle measurements. With the increase in the fraction of crosslinker in the feed, the thickness of the grafted layer increased and the surface became smooth. All the brush-coated SS surfaces could effectively reduce the adhesion of bacteria and microalgae and settlement of barnacle cyprids, as compared to the pristine SS surface. The antifouling efficacy of the PEGMA polymer (PPEGMA)-grafted surface was higher than that of the MPC polymer (PMPC)-grafted surfaces. Furthermore, the crosslinked hydrogel brush-grafted surfaces exhibited better fouling resistance than the non-crosslinked polymer brush-grafted surfaces, and the antifouling efficacy increased with the crosslinking density. These hydrogel coatings of low toxicity and excellent anti-adhesive characteristics suggested their useful applications as environmentally friendly antifouling coatings.

  15. Hydrogel brushes grafted from stainless steel via surface-initiated atom transfer radical polymerization for marine antifouling

    International Nuclear Information System (INIS)

    Wang, Jingjing; Wei, Jun

    2016-01-01

    Highlights: • Crosslinked hydrogel brushes were grafted from SS surfaces for marine antifouling. • All brush-coated SS surfaces could effectively reduce the adhesion of biofouling. • The antifouling efficacy increased with the crosslinking density of hydrogels. - Abstract: Crosslinked hydrogel brushes were grafted from stainless steel (SS) surfaces for marine antifouling. The brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) respectively with different fractions of crosslinker in the feed. The grafted layers prepared with different thickness were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ellipsometry and water contact angle measurements. With the increase in the fraction of crosslinker in the feed, the thickness of the grafted layer increased and the surface became smooth. All the brush-coated SS surfaces could effectively reduce the adhesion of bacteria and microalgae and settlement of barnacle cyprids, as compared to the pristine SS surface. The antifouling efficacy of the PEGMA polymer (PPEGMA)-grafted surface was higher than that of the MPC polymer (PMPC)-grafted surfaces. Furthermore, the crosslinked hydrogel brush-grafted surfaces exhibited better fouling resistance than the non-crosslinked polymer brush-grafted surfaces, and the antifouling efficacy increased with the crosslinking density. These hydrogel coatings of low toxicity and excellent anti-adhesive characteristics suggested their useful applications as environmentally friendly antifouling coatings.

  16. Fabrication of ultrahydrophobic poly(lauryl acrylate) brushes on silicon wafer via surface-initiated atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Oztuerk, Esra; Turan, Eylem [Department of Chemistry, Faculty of Art and Science, Gazi University, 06500 Besevler, Ankara (Turkey); Caykara, Tuncer, E-mail: caykara@gazi.edu.tr [Department of Chemistry, Faculty of Art and Science, Gazi University, 06500 Besevler, Ankara (Turkey)

    2010-11-15

    In this report, ultrahydrophobic poly(lauryl acrylate) [poly(LA)] brushes were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) of lauryl acrylate (LA) in N,N-dimethylformamide (DMF) at 90 deg. C. The formation of ultrahydrophobic poly(LA) films, whose thickness can be turned by changing polymerization time, is evidenced by using the combination of ellipsometry, X-ray photoelectron spectroscopy (XPS), grazing angle attenuated total reflectance-Fourier transform infrared spectroscopy (GATR-FTIR), atomic force microscopy (AFM), gel permeation chromatography (GPC), and water contact angle measurements. The SI-ATRP can be conducted in a well-controlled manner, as revealed by the linear kinetic plot, linear evolution of number-average molecular weights (M-bar{sub n}) versus monomer conversions, and the relatively narrow PDI (<1.28) of the grafted poly(LA) chains. The calculation of grafting parameters from experimental measurements indicated the synthesis of densely grafted poly(LA) films and allowed us to predict a 'brushlike' conformation for the chains in good solvent. The poly(LA) brushes exhibited high water contact angle of 163.3 {+-} 2.8{sup o}.

  17. Hydrogel brushes grafted from stainless steel via surface-initiated atom transfer radical polymerization for marine antifouling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jingjing, E-mail: jjwang1@hotmail.com; Wei, Jun

    2016-09-30

    Highlights: • Crosslinked hydrogel brushes were grafted from SS surfaces for marine antifouling. • All brush-coated SS surfaces could effectively reduce the adhesion of biofouling. • The antifouling efficacy increased with the crosslinking density of hydrogels. - Abstract: Crosslinked hydrogel brushes were grafted from stainless steel (SS) surfaces for marine antifouling. The brushes were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) respectively with different fractions of crosslinker in the feed. The grafted layers prepared with different thickness were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ellipsometry and water contact angle measurements. With the increase in the fraction of crosslinker in the feed, the thickness of the grafted layer increased and the surface became smooth. All the brush-coated SS surfaces could effectively reduce the adhesion of bacteria and microalgae and settlement of barnacle cyprids, as compared to the pristine SS surface. The antifouling efficacy of the PEGMA polymer (PPEGMA)-grafted surface was higher than that of the MPC polymer (PMPC)-grafted surfaces. Furthermore, the crosslinked hydrogel brush-grafted surfaces exhibited better fouling resistance than the non-crosslinked polymer brush-grafted surfaces, and the antifouling efficacy increased with the crosslinking density. These hydrogel coatings of low toxicity and excellent anti-adhesive characteristics suggested their useful applications as environmentally friendly antifouling coatings.

  18. Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Huihui; Qian, Bin; Zhang, Wei [Shanghai Key Laboratory of Functional Materials Chemistry and Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); Lan, Minbo, E-mail: minbolan@ecust.edu.cn [Shanghai Key Laboratory of Functional Materials Chemistry and Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2016-02-15

    Highlights: • Antifouling PVP brushes were successfully grafted on PU films by SI-ATRP. • The effect of polymerization time on surface property and topography was studied. • Hydrophilicity and protein fouling resistance of PVP–PU films were greatly promoted. • Competitive adsorption of three proteins on PVP–PU films was evaluated. - Abstract: An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU–PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU–PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU–PVP (6.0 h) film reduced greatly to 0.08 μg/cm{sup 2}, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

  19. Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Yuan, Huihui; Qian, Bin; Zhang, Wei; Lan, Minbo

    2016-01-01

    Highlights: • Antifouling PVP brushes were successfully grafted on PU films by SI-ATRP. • The effect of polymerization time on surface property and topography was studied. • Hydrophilicity and protein fouling resistance of PVP–PU films were greatly promoted. • Competitive adsorption of three proteins on PVP–PU films was evaluated. - Abstract: An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU–PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU–PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU–PVP (6.0 h) film reduced greatly to 0.08 μg/cm"2, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

  20. Ternary hybrid polymeric nanocomposites through grafting of polystyrene on graphene oxide-TiO{sub 2} by surface initiated atom transfer radical polymerization (SI-ATRP)

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Arvind; Bansal, Ankushi; Behera, Babita; Jain, Suman L.; Ray, Siddharth S., E-mail: ssray@iip.res.in

    2016-04-01

    A ternary hybrid of graphene oxide-titania-polystyrene (GO-TiO{sub 2}-PS) nanocomposite is developed where polystyrene composition is regulated by controlling growth of polymer chains and nanoarchitectonics is discussed. Graphene Oxide-TiO{sub 2} (GO-TiO{sub 2}) nanocomposite is prepared by in-situ hydrothermal method and the surface is anchored with α-bromoisobutyryl bromide to activate GO-TiO{sub 2} as initiator for polymerization. In-situ grafting of polystyrene through surface initiated atom transfer radical polymerization (SI- ATRP) on this Br-functionalized nano-composite initiator yields GO-TiO{sub 2}-PS ternary hybrid. Varying the monomer amount and keeping the concentration of initiator constant, polystyrene chain growth is regulated with narrow poly-dispersivity to achieve desired composition. This composite is well characterized by various analytical techniques like FTIR, XRD, DSC, SEM, TEM, and TGA. - Highlights: • Nanocomposite of ternary hybrid of GO-TiO{sub 2} with polystyrene. • PS is surface grafted on GO-TiO{sub 2}. • Polymer chain lengths are well regulated by SI-ATRP living polymerization. • Thermal stability of this hybrid is relatively high.

  1. Ternary hybrid polymeric nanocomposites through grafting of polystyrene on graphene oxide-TiO_2 by surface initiated atom transfer radical polymerization (SI-ATRP)

    International Nuclear Information System (INIS)

    Kumar, Arvind; Bansal, Ankushi; Behera, Babita; Jain, Suman L.; Ray, Siddharth S.

    2016-01-01

    A ternary hybrid of graphene oxide-titania-polystyrene (GO-TiO_2-PS) nanocomposite is developed where polystyrene composition is regulated by controlling growth of polymer chains and nanoarchitectonics is discussed. Graphene Oxide-TiO_2 (GO-TiO_2) nanocomposite is prepared by in-situ hydrothermal method and the surface is anchored with α-bromoisobutyryl bromide to activate GO-TiO_2 as initiator for polymerization. In-situ grafting of polystyrene through surface initiated atom transfer radical polymerization (SI- ATRP) on this Br-functionalized nano-composite initiator yields GO-TiO_2-PS ternary hybrid. Varying the monomer amount and keeping the concentration of initiator constant, polystyrene chain growth is regulated with narrow poly-dispersivity to achieve desired composition. This composite is well characterized by various analytical techniques like FTIR, XRD, DSC, SEM, TEM, and TGA. - Highlights: • Nanocomposite of ternary hybrid of GO-TiO_2 with polystyrene. • PS is surface grafted on GO-TiO_2. • Polymer chain lengths are well regulated by SI-ATRP living polymerization. • Thermal stability of this hybrid is relatively high.

  2. Controlled Grafting of Poly(methyl methacrylate) Brushes on Poly(vinylidene fluoride) Powders by Surface-initiated Atom Transfer Radical Polymerization

    Institute of Scientific and Technical Information of China (English)

    TANG Zhaoqi; LI Wei; LIU Lanqin; HUANG Lei; ZHOU Jin; YU Haiyin

    2009-01-01

    Controlled grafting of well-defined polymer brushes of methyl methacrylate (MMA) on the poly(vinylidene fluoride) (PVDF) powders was carded out by the surface-initiated atom transfer radical polymerization (ATRP). The ATRP initiator was anchored on the PVDF surface by alkaline treatment, followed by UV-induced bromination; then methyl methacrylate (MMA) was grafted onto the brominated PVDF by the ATRP technique. The chemical composition changes of PVDF were characterized by Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS results clearly indicated the successful graft of poly(methyl methacrylate) onto the PVDF surface.

  3. Surface-Initiated Atom Transfer Radical Polymerization and Electrografting Technique as a Means For Attaining Tailor-Made Polymer Coatings

    DEFF Research Database (Denmark)

    Chernyy, Sergey

    2012-01-01

    strategies for initiator grafting, physicochemical properties of polymer brushes and basic principles of quartz crystal microbalance technique (QCM) are discussed. In Chapter 2 various ATRP conditions are probed. The effects of solvent polarity, monomer concentration, initiator surface density, ligand nature......Atom transfer radical polymerization initiated from a surface of various substrates (SI-ATRP) has become a progressively popular technique for obtaining thin polymer films with predetermined properties. The present work addresses the main features of SI-ATRP with respect to the controllability...... and temperature on the kinetics of methyl methacrylate polymerization are elucidated. The strategy was based on the observation of dry polymer thickness versus time evolution by means of ellipsometry, profilometry and IR spectroscopy. An alternative approach, constituting Chapter 3, was based on optimization...

  4. Grafting of antibacterial polymers on stainless steel via surface-initiated atom transfer radical polymerization for inhibiting biocorrosion by Desulfovibrio desulfuricans.

    Science.gov (United States)

    Yuan, S J; Xu, F J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

    2009-06-01

    To enhance the biocorrosion resistance of stainless steel (SS) and to impart its surface with bactericidal function for inhibiting bacterial adhesion and biofilm formation, well-defined functional polymer brushes were grafted via surface-initiated atom transfer radical polymerization (ATRP) from SS substrates. The trichlorosilane coupling agent, containing the alkyl halide ATRP initiator, was first immobilized on the hydroxylated SS (SS-OH) substrates for surface-initiated ATRP of (2-dimethylamino)ethyl methacrylate (DMAEMA). The tertiary amino groups of covalently immobilized DMAEMA polymer or P(DMAEMA), brushes on the SS substrates were quaternized with benzyl halide to produce the biocidal functionality. Alternatively, covalent coupling of viologen moieties to the tertiary amino groups of P(DMAEMA) brushes on the SS surface resulted in an increase in surface concentration of quaternary ammonium groups, accompanied by substantially enhanced antibacterial and anticorrosion capabilities against Desulfovibrio desulfuricans in anaerobic seawater, as revealed by antibacterial assay and electrochemical studies. With the inherent advantages of high corrosion resistance of SS, and the good antibacterial and anticorrosion capabilities of the viologen-quaternized P(DMAEMA) brushes, the functionalized SS is potentially useful in harsh seawater environments and for desalination plants. Copyright 2009 Wiley Periodicals, Inc.

  5. Crystalline TiO{sub 2} grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom-transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Yuancong; Tu Qiufen; Wang Jin; Huang Qiongjian [Key Lab. of Advanced Technology for Materials, Education Ministry, School of Material Science and Technology of Southwest Jiaotong University, Chengdu, Sichuan (China); Huang Nan, E-mail: zhaoyc7320@163.com [Key Lab. of Advanced Technology for Materials, Education Ministry, School of Material Science and Technology of Southwest Jiaotong University, Chengdu, Sichuan (China)

    2010-12-15

    Crystalline TiO{sub 2} films were prepared by unbalanced magnetron sputtering and the structure was confirmed by XRD. An organic layer of 11-hydroxyundecylphosphonic acid (HUPA) was prepared on the TiO{sub 2} films by self-assembling, and the HUPA on TiO{sub 2} films was confirmed by FTIR analysis. Simultaneously, hydroxyl groups were introduced in the phosphonic acid molecules to provide a functionality for further chemical modification. 2-Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was chemically grafted on the HUPA surfaces at room temperature by surface-initiated atom-transfer radical polymerization. The surface characters of TiO{sub 2} films modified by poly-MPC were confirmed by FTIR, XPS and SEM analysis. Platelet adhesion experiment revealed that poly-MPC modified surface was effective to inhibit platelet adhesion in vitro.

  6. Surface modification of thermoplastic poly(vinyl alcohol)/saponite nanocomposites via surface-initiated atom transfer radical polymerization enhanced by air dielectric discharges barrier plasma treatment

    International Nuclear Information System (INIS)

    Zhen Weijun; Lu Canhui

    2012-01-01

    To improve the water resistance of thermoplastic poly(vinyl alcohol)/saponite nanocomposites (TPVA), a simple two-step method was developed for the covalent immobilization of atom transfer radical polymerization (ATRP) initiators on the TPVA surfaces enhanced by air dielectric barrier discharges (DBD) plasma treatment, and hydrophobic poly(methyl methacrylate) (PMMA) brushes were then grafted onto the surface of TPVA via surface-initiated atom transfer radical polymerization (SI-ATRP). The chemical composition, morphology and hydrophobicity of the modified TPVA surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The water resistance of the surface-functionalized PMMA was evaluated by the contact angle and water adsorption method. It was shown that air DBD plasma treatment activated the TPVA surface and accelerated the immobilization of ATRP initiator on the TPVA surface. Compared with TPVA control, TPVA modified by SI-ATRP can be grafted well-defined and covalently tethered network PMMA brushes onto the surface and the hydrophobicity of TPVA were significantly enhanced.

  7. Surface polyPEGylation of Eu3+ doped luminescent hydroxyapatite nanorods through the combination of ligand exchange and metal free surface initiated atom transfer radical polymerization

    Science.gov (United States)

    Zeng, Guangjian; Liu, Meiying; Heng, Chunning; Huang, Qiang; Mao, Liucheng; Huang, Hongye; Hui, Junfeng; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2017-03-01

    The Eu3+ doped luminescent hydroxyapatite (HAp) nanorods with uniform size and morphology can be synthesized by hydrothermal route. However, these HAp nanorods are coated by hydrophobic oleylamine, which makes them difficult to be dispersed in aqueous solution and impede their biomedical applications. In this work, Eu3+ doped luminescent polymers functionalized HAp nanorods were prepared through the combination of ligand exchange reaction and metal free surface initiated atom transfer radical polymerization (ATRP) method. In this procedure, the amino group functionalized HAp nanorods were first prepared by ligand exchange reaction using adenosine monophosphate (AMP) as ligand. Then the Br-containing initiators (HAp-Br) were introduced onto the surface of HAp-AMP nanorods through the amidation reaction. Finally, polymers functionalized HAp nanorods were prepared by metal free ATRP method using poly(ethylene glycol) methacrylate (PEGMA) as monomer and 10-phenylphenothiazine (PTH) as organic photocatalyst. The properties of these obtained HAp nanocomposites (HAP-polyPEGMA nanorods) were characterized by means of transmission electron microscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis in detail. The cell imaging of these HAP-polyPEGMA nanorods was examined using laser scanning confocal microscope to evaluate their biomedical applications. We demonstrated for the first time that hydrophobic luminescent HAp nanorods can be functionalized with polyPEGMA through the combination of ligand exchange reaction and metal free surface initiated ATRP. As compared with the traditional ATRP, the metal free ATRP can overcome the toxic and fluorescence quenching effects of metal catalysts such as copper ions. More importantly, the strategy described in this work should also be utilized for fabrications of many other luminescent polymer nanocomposites due to its good monomer adoptability.

  8. Poly(glycidyl methacrylate) grafted CdSe quantum dots by surface-initiated atom transfer radical polymerization: Novel synthesis, characterization, properties, and cytotoxicity studies

    Energy Technology Data Exchange (ETDEWEB)

    Bach, Long Giang; Islam, Md. Rafiqul [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Lee, Doh Chang [Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury (KINC), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Lim, Kwon Taek, E-mail: ktlim@pknu.ac.kr [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2013-10-15

    A novel approach for the synthesis of poly(glycidyl methacrylate) grafted CdSe quantum dot (QDs) (PGMA-g-CdSe) was developed. The PGMA-g-CdSe nanohybrids were synthesized by the surface-initiated atom transfer radical polymerization of glycidyl methacrylate from the surface of the strategic initiator, CdSe-BrIB QDs prepared by the interaction of 2-bromoisobutyryl bromide (BrIB) and CdSe-OH QDs. The structure, morphology, and optical property of the PGMA-g-CdSe nanohybrids were analyzed by FT-IR, XPS, TGA, XRD, TEM, and PL. The as-synthesized PGMA-g-CdSe nanohybrids having multi-epoxide groups were employed for the direct coupling of biotin via ring-opening reaction of the epoxide groups to afford the Biotin-f-PGMA-g-CdSe nanobioconjugate. The covalent immobilization of biotin onto PGMA-g-CdSe was confirmed by FT-IR, XPS, and EDX. Biocompatibility and imaging properties of the Biotin-f-PGMA-g-CdSe were investigated by MTT bioassay and PL analysis, respectively. The cell viability study suggested that the biocompatibility was significantly enhanced by the functionalization of CdSe QDs by biotin and PGMA.

  9. Preparation of Mg(OH)_2 hybrid pigment by direct precipitation and graft onto cellulose fiber via surface-initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Wang, Xiao; Zhang, Yue; Lv, Lihua; Cui, Yongzhu; Wei, Chunyan; Pang, Guibing

    2016-01-01

    Graphical abstract: - Highlights: • Adsorbed anionic dye molecules are conducive to preferential growth of (0 0 1) plane of Mg(OH)_2 crystal for Mg(OH)_2 pigments. • Uniform coverage of nanosized Mg(OH)_2 pigments on fiber surface is achieved via surface-initiated ATRP. • About 4 wt% of Mg(OH)_2 pigment on fiber surface shortens nearly half of burning time of cellulose. - Abstract: Mg(OH)_2 flame retardant hybrid pigment is synthesized through simultaneous solution precipitation and adsorption of anionic dyes (C.I. Acid Red 6). The Mg(OH)_2 hybrid pigment bearing vinyl groups after surface silane modification is immobilized onto the surface of bromo end-functional cellulose fiber by atom transfer radical polymerization (ATRP). The morphology and structure of Mg(OH)_2 pigments and cellulose fibers grafted with modified pigments are characterized. The thermal properties, flammability and color fastness of cellulose fibers grafted with modified pigments are measured. The results reveal that anionic dye molecules are adsorbed onto Mg(OH)_2 crystals and affect the formation of lamella-like Mg(OH)_2 crystals. The cellulose fiber grafted with modified Mg(OH)_2 hybrid pigment absorbs about four times heat more than original cellulose fiber with about 4% immobilization ratio of pigment, which shortens nearly half of afterflame time and afterglow time.

  10. Surface-Initiated Atom Transfer Radical Polymerization of Magnetite Nanoparticles with Statistical Poly(tert-butyl acrylate-poly(poly(ethylene glycol methyl ether methacrylate Copolymers

    Directory of Open Access Journals (Sweden)

    Patcharin Kanhakeaw

    2015-01-01

    Full Text Available This work presented the surface modification of magnetite nanoparticle (MNP with poly[(t-butyl acrylate-stat-(poly(ethylene glycol methyl ether methacrylate] copolymers (P[(t-BA-stat-PEGMA] via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP. Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp. such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water, can be fine-tuned. The reaction progress in each step of the synthesis was monitored via Fourier transform infrared spectroscopy (FTIR. The studies in the reaction kinetics indicated that PEGMA had higher reactivity than that of t-BA in the copolymerizations. Gel permeation chromatography (GPC indicated that the molecular weights of the copolymers increased with the increase of the monomer conversion. Transmission electron microscopy (TEM revealed that the particles were spherical with averaged size of 8.1 nm in diameter. Dispersibility of the particles in water was apparently improved when the copolymers were coated as compared to P(t-BA homopolymer coating. The percentages of MNP and the copolymer in the composites were determined via thermogravimetric analysis (TGA and their magnetic properties were investigated via vibrating sample magnetometry (VSM.

  11. Synthesis and characterization of TiO2/Ag/polymer ternary nanoparticles via surface-initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Park, Jung Tae; Koh, Joo Hwan; Seo, Jin Ah; Cho, Yong Soo; Kim, Jong Hak

    2011-01-01

    We report on the novel ternary hybrid materials consisting of semiconductor (TiO 2 ), metal (Ag) and polymer (poly(oxyethylene methacrylate) (POEM)). First, a hydrophilic polymer, i.e. POEM, was grafted from TiO 2 nanoparticles via the surface-initiated atom transfer radical polymerization (ATRP) technique. These TiO 2 -POEM brush nanoparticles were used to template the formation of Ag nanoparticles by introduction of a AgCF 3 SO 3 precursor and a NaBH 4 aqueous solution for reduction process. Successful grafting of polymeric chains from the surface of TiO 2 nanoparticles and the in situ formation of Ag nanoparticles within the polymeric chains were confirmed using transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). FT-IR spectroscopy also revealed the specific interaction of Ag nanoparticles with the C=O groups of POEM brushes. This study presents a simple route for the in situ synthesis of both metal and polymer confined within the semiconductor, producing ternary hybrid inorganic-organic nanomaterials.

  12. Antibacterial inorganic-organic hybrid coatings on stainless steel via consecutive surface-initiated atom transfer radical polymerization for biocorrosion prevention.

    Science.gov (United States)

    Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

    2010-05-04

    To enhance the corrosion resistance of stainless steel (SS) and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, well-defined inorganic-organic hybrid coatings, consisting of a polysilsesquioxane inner layer and quaternized poly(2-(dimethyamino)ethyl methacrylate) (P(DMAEMA)) outer blocks, were prepared via successive surface-initiated atom transfer radical polymerization (ATRP) of 3-(trimethoxysilyl)propyl methacrylate (TMSPMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). The cross-linked P(TMASPMA), or polysilsesquioxane, inner layer provided a durable and resistant coating to electrolytes. The pendant tertiary amino groups of the P(DMAEMA) outer block were quaternized with alkyl halide to produce a high concentration of quaternary ammonium groups with biocidal functionality. The so-synthesized inorganic-organic hybrid coatings on the SS substrates exhibited good anticorrosion and antibacterial effects and inhibited biocorrosion induced by sulfate-reducing bacteria (SRB) in seawater media, as revealed by antibacterial assay and electrochemical analyses, and they are potentially useful to steel-based equipment under harsh industrial and marine environments.

  13. Inorganic-organic hybrid coatings on stainless steel by layer-by-layer deposition and surface-initiated atom-transfer-radical polymerization for combating biocorrosion.

    Science.gov (United States)

    Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

    2009-03-01

    To improve the biocorrosion resistance of stainless steel (SS) and to confer the bactericidal function on its surface for inhibiting bacterial adhesion and biofilm formation, well-defined inorganic-organic hybrid coatings, consisting of the inner compact titanium oxide multilayers and outer dense poly(vinyl-N-hexylpyridinium) brushes, were successfully developed. Nanostructured titanium oxide multilayer coatings were first built up on the SS substrates via the layer-by-layer sol-gel deposition process. The trichlorosilane coupling agent, containing the alkyl halide atom-transfer-radical polymerization (ATRP) initiator, was subsequently immobilized on the titanium oxide coatings for surface-initiated ATRP of 4-vinylpyridine (4VP). The pyridium nitrogen moieties of the covalently immobilized 4VP polymer, or P(4VP), brushes were quaternized with hexyl bromide to produce a high concentration of quaternary ammonium salt on the SS surfaces. The excellent antibacterial efficiency of the grafted polycations, poly(vinyl-N-pyridinium bromide), was revealed by viable cell counts and atomic force microscopy images of the surface. The effectiveness of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements.

  14. Poly(glycidyl methacrylate) grafted CdSe quantum dots by surface-initiated atom transfer radical polymerization: Novel synthesis, characterization, properties, and cytotoxicity studies

    International Nuclear Information System (INIS)

    Bach, Long Giang; Islam, Md. Rafiqul; Lee, Doh Chang; Lim, Kwon Taek

    2013-01-01

    A novel approach for the synthesis of poly(glycidyl methacrylate) grafted CdSe quantum dot (QDs) (PGMA-g-CdSe) was developed. The PGMA-g-CdSe nanohybrids were synthesized by the surface-initiated atom transfer radical polymerization of glycidyl methacrylate from the surface of the strategic initiator, CdSe-BrIB QDs prepared by the interaction of 2-bromoisobutyryl bromide (BrIB) and CdSe-OH QDs. The structure, morphology, and optical property of the PGMA-g-CdSe nanohybrids were analyzed by FT-IR, XPS, TGA, XRD, TEM, and PL. The as-synthesized PGMA-g-CdSe nanohybrids having multi-epoxide groups were employed for the direct coupling of biotin via ring-opening reaction of the epoxide groups to afford the Biotin-f-PGMA-g-CdSe nanobioconjugate. The covalent immobilization of biotin onto PGMA-g-CdSe was confirmed by FT-IR, XPS, and EDX. Biocompatibility and imaging properties of the Biotin-f-PGMA-g-CdSe were investigated by MTT bioassay and PL analysis, respectively. The cell viability study suggested that the biocompatibility was significantly enhanced by the functionalization of CdSe QDs by biotin and PGMA.

  15. Preparation of high-capacity, weak anion-exchange membranes by surface-initiated atom transfer radical polymerization of poly(glycidyl methacrylate) and subsequent derivatization with diethylamine

    International Nuclear Information System (INIS)

    Qian, Xiaolei; Fan, Hua; Wang, Chaozhan; Wei, Yinmao

    2013-01-01

    Ion-exchange membrane is of importance for the development of membrane chromatography. In this work, a high-capacity anion-exchange membrane was prepared by grafting of glycidyl methacrylate (GMA) onto the surface of regenerated cellulose (RC) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequent derivatization with diethylamine. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to characterize changes in the chemical functionality, surface topography and pore morphology of the modified membranes. The static capacity of the prepared anion-exchange membrane was evaluated with bovine serum albumin (BSA) as a model protein. The results indicated that the anion-exchange membrane which could reach a maximum capacity of 96 mg/mL for static adsorption possesses a higher adsorption capacity, and the adsorption capacity increases with the polymerization time. The effect of pH and salt concentration confirmed that the adsorption of BSA followed ion-exchange mechanism. The established method would have potential application in the preparation of anion-exchange membrane.

  16. Surface polyPEGylation of Eu{sup 3+} doped luminescent hydroxyapatite nanorods through the combination of ligand exchange and metal free surface initiated atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Guangjian; Liu, Meiying [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Heng, Chunning [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi’an 710069 (China); Huang, Qiang; Mao, Liucheng; Huang, Hongye [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Hui, Junfeng [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi’an 710069 (China); Deng, Fengjie, E-mail: fengjiedeng@aliyun.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and The Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China)

    2017-03-31

    Highlights: • Surface modification of HAp nanorods through the combination of ligand exchange reaction and metal free SI-ATRP. • HAp-polyPEGMA displayed high water dispersibility, good biocompatibility and biological imaging capability. • Metal free ATRP can overcome the toxic and fluorescence quenching effects of metal catalysts of conventional ATRP. - Abstract: The Eu{sup 3+} doped luminescent hydroxyapatite (HAp) nanorods with uniform size and morphology can be synthesized by hydrothermal route. However, these HAp nanorods are coated by hydrophobic oleylamine, which makes them difficult to be dispersed in aqueous solution and impede their biomedical applications. In this work, Eu{sup 3+} doped luminescent polymers functionalized HAp nanorods were prepared through the combination of ligand exchange reaction and metal free surface initiated atom transfer radical polymerization (ATRP) method. In this procedure, the amino group functionalized HAp nanorods were first prepared by ligand exchange reaction using adenosine monophosphate (AMP) as ligand. Then the Br-containing initiators (HAp-Br) were introduced onto the surface of HAp-AMP nanorods through the amidation reaction. Finally, polymers functionalized HAp nanorods were prepared by metal free ATRP method using poly(ethylene glycol) methacrylate (PEGMA) as monomer and 10-phenylphenothiazine (PTH) as organic photocatalyst. The properties of these obtained HAp nanocomposites (HAP-polyPEGMA nanorods) were characterized by means of transmission electron microscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis in detail. The cell imaging of these HAP-polyPEGMA nanorods was examined using laser scanning confocal microscope to evaluate their biomedical applications. We demonstrated for the first time that hydrophobic luminescent HAp nanorods can be functionalized with polyPEGMA through the combination of ligand exchange reaction and metal free surface

  17. Surface polyPEGylation of Eu"3"+ doped luminescent hydroxyapatite nanorods through the combination of ligand exchange and metal free surface initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Zeng, Guangjian; Liu, Meiying; Heng, Chunning; Huang, Qiang; Mao, Liucheng; Huang, Hongye; Hui, Junfeng; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2017-01-01

    Highlights: • Surface modification of HAp nanorods through the combination of ligand exchange reaction and metal free SI-ATRP. • HAp-polyPEGMA displayed high water dispersibility, good biocompatibility and biological imaging capability. • Metal free ATRP can overcome the toxic and fluorescence quenching effects of metal catalysts of conventional ATRP. - Abstract: The Eu"3"+ doped luminescent hydroxyapatite (HAp) nanorods with uniform size and morphology can be synthesized by hydrothermal route. However, these HAp nanorods are coated by hydrophobic oleylamine, which makes them difficult to be dispersed in aqueous solution and impede their biomedical applications. In this work, Eu"3"+ doped luminescent polymers functionalized HAp nanorods were prepared through the combination of ligand exchange reaction and metal free surface initiated atom transfer radical polymerization (ATRP) method. In this procedure, the amino group functionalized HAp nanorods were first prepared by ligand exchange reaction using adenosine monophosphate (AMP) as ligand. Then the Br-containing initiators (HAp-Br) were introduced onto the surface of HAp-AMP nanorods through the amidation reaction. Finally, polymers functionalized HAp nanorods were prepared by metal free ATRP method using poly(ethylene glycol) methacrylate (PEGMA) as monomer and 10-phenylphenothiazine (PTH) as organic photocatalyst. The properties of these obtained HAp nanocomposites (HAP-polyPEGMA nanorods) were characterized by means of transmission electron microscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis in detail. The cell imaging of these HAP-polyPEGMA nanorods was examined using laser scanning confocal microscope to evaluate their biomedical applications. We demonstrated for the first time that hydrophobic luminescent HAp nanorods can be functionalized with polyPEGMA through the combination of ligand exchange reaction and metal free surface initiated

  18. Metal-catalyzed living radical polymerization and radical polyaddition for precision polymer synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mizutani, M; Satoh, K [Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kamigaito, M, E-mail: kamigait@apchem.nagoya-u.ac.j

    2009-08-01

    The metal-catalyzed radical addition reaction can be evolved into two different polymerization mechanisms, i.e.; chain- and step-growth polymerizations, while both the polymerizations are based on the same metal-catalyzed radical formation reaction. The former is a widely employed metal-catalyzed living radical polymerization or atom transfer radical polymerization of common vinyl monomers, and the latter is a novel metal-catalyzed radical polyaddition of designed monomer with an unconjugated C=C double bond and a reactive C-Cl bond in one molecule. The simultaneous ruthenium-catalyzed living radical polymerization of methyl acrylate and radical polyaddition of 3-butenyl 2-chloropropionate was achieved with Ru(Cp*)Cl(PPh{sub 3}){sub 2} to afford the controlled polymers, in which the homopolymer segments with the controlled chain length were connected by the ester linkage.

  19. Fast Resonance Raman Spectroscopy of Short-Lived Radicals

    DEFF Research Database (Denmark)

    Pagsberg, Palle Bjørn; Wilbrandt, Robert Walter; Hansen, Karina Benthin

    1976-01-01

    We report the first application of pulsed resonance Raman spectroscopy to the study of short-lived free radicals produced by pulse radiolysis. A single pulse from a flash-lamp pumped tunable dye laser is used to excite the resonance Raman spectrum of the p-terphenyl anion radical with an initial...

  20. Long-lived gas-phase radicals from combustion

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Takashi; Furusawa, Koji; Amano, Toshiji; Okubo, Yoichi; Tsuchiya, Jun' ichi; Yoshizawa, Fujiroku; Akutsu, Yoshiaki; Tamura, Masamitsu; Yoshida, Tadao (Univ. of Tokyo (Japan))

    1989-04-20

    On indoor air pollution or fire, it is feared that the gas-phase radicals from the combustion of inflammables or fuel seriously exert an influence on the organisms as harmful matter. The gas-phase radicals were studied using the electron spin resonance (ESR) spin-trapping technique. For the spin trap solution, 0.1 mol solution of {alpha}-phenyl-N-t-butylnitron in benzene was used. As a result, apparently long-lived and highly reactive oxygen-centered radicals were detected in the smoke from polyethylene, polypropylene, polystyrene, polymethylmethacrylate, cellulose, kerosene, benzene, acetone, methanol and butylalcohol. It is suggested that the production mechanism for the radicals should be different from olefin-NOx-air system reaction, which is considered for the radicals from cigarette smoke. 11 refs., 6 figs., 2 tabs.

  1. Oxygen radical microscopy in living plant tissues

    DEFF Research Database (Denmark)

    Kristiansen, Kim Anker; Møller, Ian Max; Schulz, Alexander

    the ROS production stems from the mitochondria and peroxisomes as is seen in animal cells. At the Bioimaging Center at KVL we employ different techniques to induce, detect and monitor ROS production, distribution and in and among living plant cells. Both confocal laser scanning microscopy and 2-photon......Reactive oxygen species (ROS) play a crucial role in a wide variety of processes. Initiation of many different cellular pathways, crosstalk between cells, developmental signalling in planta, programmed cell death and hypersensitive response in connection with plant-pathogen interactions are among...... the different roles ROS play. On the other hand ROS also cause damage to cellular components at sub-lethal to lethal levels. In photosynthesizing plants the major production of ROS origin from the chloroplast. ROS is a by product from the Photosystem I/II handling of light energy. In nonphotosynthesizing plants...

  2. Macromolecular Architectures Designed by Living Radical Polymerization with Organic Catalysts

    Directory of Open Access Journals (Sweden)

    Miho Tanishima

    2014-01-01

    Full Text Available Well-defined diblock and triblock copolymers, star polymers, and concentrated polymer brushes on solid surfaces were prepared using living radical polymerization with organic catalysts. Polymerizations of methyl methacrylate, butyl acrylate, and selected functional methacrylates were performed with a monofunctional initiator, a difunctional initiator, a trifunctional initiator, and a surface-immobilized initiator.

  3. Living atom transfer radical polymerization of 4-acetoxystyrene

    DEFF Research Database (Denmark)

    Gao, Bo; Chen, Xianyi; Ivan, Bela

    1997-01-01

    Living atom transfer radical polymerization (ATRP) of 4-acetoxystyrene (1), a protected 4-vinylphenol, leading to poly(4-acetoxystyrene) with well-defined molecular weight and narrow molecular weight distribution was carried out in bulk with a,a'-dibromoxylene(2)/CuBr/2,2-bipyridine(bpy) as initi......Living atom transfer radical polymerization (ATRP) of 4-acetoxystyrene (1), a protected 4-vinylphenol, leading to poly(4-acetoxystyrene) with well-defined molecular weight and narrow molecular weight distribution was carried out in bulk with a,a'-dibromoxylene(2)/CuBr/2,2-bipyridine......(bpy) as initiating system. A linear (M) over bar(n), versus monomer conversion plot was found in good accordance with the theoretical line, indicating 100% initiating efficiency. The polymerization is first order in respect to monomer up to about 70% monomer conversion. Deviations from linearity at higher conversion...

  4. Preparation of Transparent Bulk TiO2/PMMA Hybrids with Improved Refractive Indices via an in Situ Polymerization Process Using TiO2 Nanoparticles Bearing PMMA Chains Grown by Surface-Initiated Atom Transfer Radical Polymerization.

    Science.gov (United States)

    Maeda, Satoshi; Fujita, Masato; Idota, Naokazu; Matsukawa, Kimihiro; Sugahara, Yoshiyuki

    2016-12-21

    Transparent TiO 2 /PMMA hybrids with a thickness of 5 mm and improved refractive indices were prepared by in situ polymerization of methyl methacrylate (MMA) in the presence of TiO 2 nanoparticles bearing poly(methyl methacrylate) (PMMA) chains grown using surface-initiated atom transfer radical polymerization (SI-ATRP), and the effect of the chain length of modified PMMA on the dispersibility of modified TiO 2 nanoparticles in the bulk hybrids was investigated. The surfaces of TiO 2 nanoparticles were modified with both m-(chloromethyl)phenylmethanoyloxymethylphosphonic acid bearing a terminal ATRP initiator and isodecyl phosphate with a high affinity for common organic solvents, leading to sufficient dispersibility of the surface-modified particles in toluene. Subsequently, SI-ATRP of MMA was achieved from the modified surfaces of the TiO 2 nanoparticles without aggregation of the nanoparticles in toluene. The molecular weights of the PMMA chains cleaved from the modified TiO 2 nanoparticles increased with increases in the prolonging of the polymerization period, and these exhibited a narrow distribution, indicating chain growth controlled by SI-ATRP. The nanoparticles bearing PMMA chains were well-dispersed in MMA regardless of the polymerization period. Bulk PMMA hybrids containing modified TiO 2 nanoparticles with a thickness of 5 mm were prepared by in situ polymerization of the MMA dispersion. The transparency of the hybrids depended significantly on the chain length of the modified PMMA on the nanoparticles, because the modified PMMA of low molecular weight induced aggregation of the TiO 2 nanoparticles during the in situ polymerization process. The refractive indices of the bulk hybrids could be controlled by adjusting the TiO 2 content and could be increased up to 1.566 for 6.3 vol % TiO 2 content (1.492 for pristine PMMA).

  5. "Living" free radical photopolymerization initiated from surface-grafted iniferter monolayers

    NARCIS (Netherlands)

    de Boer, B.; Simon, H.K.; Werts, M.P L; van der Vegte, E.W.; Hadziioannou, G

    2000-01-01

    A method for chemically modifying a surface with grafted monolayers of initiator groups, which can be used for a "living" free radical photopolymerization, is described. By using "living" free radical polymerizations, we were able to control the length of the grafted polymer chains and therefore the

  6. Formation of long-lived radicals on proteins by radical transfer from heme enzymes--a common process?

    DEFF Research Database (Denmark)

    Ostdal, H; Andersen, H J; Davies, Michael Jonathan

    1999-01-01

    concentrations were observed after limited digestion, although this effect was less marked with the HRP/H2O2/BSA system than with Fe(III)Mb/H2O2/BSA, consistent with different modes of radical transfer. More extensive digestion of BSA decreased the radical concentration to levels below those detected with native...... investigated using horseradish peroxidase (HRP)/H2O2, in the presence and absence of added tyrosine. Incubation of HRP with H2O2 and bovine or human serum albumins, in the presence and absence of tyrosine, gave long-lived albumin-derived radicals as detected by EPR spectroscopy. Evidence has been obtained...... for these albumin radicals being located on buried tyrosine residues on the basis of blocking experiments. The effect of protein conformation on radical transfer has been investigated using partial proteolytic digestion prior to protein oxidation. With HRP/H2O2/BSA and Fe(III)Mb/H2O2/BSA increased radical...

  7. Test for antioxidant ability by scavenging long-lived mutagenic radicals in mammalian cells and by blood test with intentional radicals: an application of gallic acid

    International Nuclear Information System (INIS)

    Kumagai, Jun; Kawaura, Tomoko; Miyazaki, Tetsuo; Prost, Michel; Prost, Emmanuelle; Watanabe, Masami; Quetin-Leclercq, J.Joeelle

    2003-01-01

    Antioxidant ability of gallic acid (GA) are determined both by electron spin resonance measurement of long-lived radicals produced in γ-ray irradiated Syrian golden hamster embryo cells with GA and by hemolysis measurement with GA when blood cells are submitted to radicals. Scavenging properties of GA are determined by the reaction rate constant with long-lived mutagenic radicals in the cells while the blood test allows to analyze the global effects of this compound: radical scavenger+metal ion chelator+regeneration of intra- and extra-cellular antioxidant

  8. Preparation of polystyrene-poly(ethylene glycol) diblock copolymer by "living" free radical polymerization

    DEFF Research Database (Denmark)

    Chen, Xianyi; Gao, Bo; Kops, Jørgen

    1998-01-01

    terminated with a TEMPO unit (MPEG-TEMPO), which was further used to prepare the diblock copolymer PS-b-PEG by 'living' free radical polymerisation of styrene. The product was purified and identified by H-1 n.m.r. and GPC. However, large amounts of homopolystyrene was also formed by simultaneous thermal...

  9. Experimental study of living free radical polymerization using trifunctional initiator and polymerization mediated by nitroxide

    International Nuclear Information System (INIS)

    Galhardo, Eduardo; Lona, Liliane M.F.

    2009-01-01

    Controlled free radical polymerization or living free radical polymerization has received increasing attention as a technique for the production of polymers with microstructure highly controlled. In particular, narrow molecular weight distributions are obtained with polydispersity very close to one. In this research it was investigate the controlled polymerization mediated by nitroxide, using a cyclic trifunctional peroxide. As long as we know, there are only publications in literature dealing with NMRP using mono- and bi-functional initiators. It was believed that the trifunctional peroxide can increase the rate of polymerization, since more free radicals are generated, if compared with initiators with lower functionality. Furthermore, the fact of the initiator be cyclic means that branches are not generated in the chains, which theoretically prevents an increase in polydispersity of the polymer. The effect of the dissociation constant of the trifunctional initiator in the velocity of the reaction was analyzed. (author)

  10. Copper-mediated homogeneous living radical polymerization of acrylamide with waxy potato starch-based macroinitiator.

    Science.gov (United States)

    Fan, Yifei; Cao, Huatang; van Mastrigt, Frank; Pei, Yutao; Picchioni, Francesco

    2018-07-15

    Cu 0 -mediated living radical polymerization (Cu 0 -mediated LRP) was employed in this research for the synthesis of starch-g-polyacrylamide (St-g-PAM). The use of a controlled radical grafting technique is necessary, as compared to the traditional free-radical polymerization methods, in order to obtain a well-defined structure of the final product. This is in turn essential for studying the relationship between such structure and the end-properties. Waxy potato starch-based water-soluble macroinitiator was first synthesized by esterification with 2-bromopropionyl bromide in the mixture of dimethylacetamide and lithium chloride. With the obtained macroinitiator, St-g-PAM was homogeneously synthesized by aqueous Cu 0 -mediated LRP using CuBr/hexamethylated tris(2-aminoethyl)amine (Me 6 Tren) as catalyst. The successful synthesis of the macroinitiator and St-g-PAM was proved by NMR, FT-IR, SEM, XRD and TGA analysis. The molecular weight and polydispersity of PAM chains were analyzed by gel permeation chromatography (GPC) after hydrolyzing the starch backbone. Monomer conversion was monitored by gas chromatography (GC), on the basis of which the kinetics were determined. A preliminarily rheological study was performed on aqueous solutions of the prepared materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Bimolecular Excited-State Electron Transfer with Surprisingly Long-Lived Radical Ions

    KAUST Repository

    Alsam, Amani Abdu

    2015-09-02

    We explored the excited-state interactions of bimolecular, non-covalent systems consisting of cationic poly[(9,9-di(3,3’-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and 1,4-dicyanobenzene (DCB) using steady-state and time-resolved techniques, including femto- and nanosecond transient absorption and femtosecond infrared spectroscopies with broadband capabilities. The experimental results demonstrated that photo-induced electron transfer from PFN to DCB occurs on the picosecond time scale, leading to the formation of PFN+• and DCB-• radical ions. Interestingly, real-time observations of the vibrational marker modes on the acceptor side provided direct evidence and insight into the electron transfer process indirectly inferred from UV-Vis experiments. The band narrowing on the picosecond time scale observed on the antisymmetric C-N stretching vibration of the DCB radical anion provides clear experimental evidence that a substantial part of the excess energy is channeled into vibrational modes of the electron transfer product and that the geminate ion pairs dissociate. More importantly, our nanosecond time-resolved data indicate that the charge-separated state is very long lived ( 30 ns) due to the dissociation of the contact radical ion pair into free ions. Finally, the fast electron transfer and slow charge recombination anticipate the current donor−acceptor system with potential applications in organic solar cells.

  12. Bimolecular Excited-State Electron Transfer with Surprisingly Long-Lived Radical Ions

    KAUST Repository

    Alsam, Amani Abdu; Aly, Shawkat Mohammede; Usman, Anwar; Parida, Manas R.; Del Gobbo, Silvano; Alarousu, Erkki; Mohammed, Omar F.

    2015-01-01

    We explored the excited-state interactions of bimolecular, non-covalent systems consisting of cationic poly[(9,9-di(3,3’-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and 1,4-dicyanobenzene (DCB) using steady-state and time-resolved techniques, including femto- and nanosecond transient absorption and femtosecond infrared spectroscopies with broadband capabilities. The experimental results demonstrated that photo-induced electron transfer from PFN to DCB occurs on the picosecond time scale, leading to the formation of PFN+• and DCB-• radical ions. Interestingly, real-time observations of the vibrational marker modes on the acceptor side provided direct evidence and insight into the electron transfer process indirectly inferred from UV-Vis experiments. The band narrowing on the picosecond time scale observed on the antisymmetric C-N stretching vibration of the DCB radical anion provides clear experimental evidence that a substantial part of the excess energy is channeled into vibrational modes of the electron transfer product and that the geminate ion pairs dissociate. More importantly, our nanosecond time-resolved data indicate that the charge-separated state is very long lived ( 30 ns) due to the dissociation of the contact radical ion pair into free ions. Finally, the fast electron transfer and slow charge recombination anticipate the current donor−acceptor system with potential applications in organic solar cells.

  13. SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)

    Institute of Scientific and Technical Information of China (English)

    Bing Liu; Feng Liu; Ning Luo; Sheng-kang Ying; Qing Liu

    2000-01-01

    Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in the polymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared by the integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum, respectively. A new way to design block copolymers (the combination of LAP and ATRP) was developed.

  14. Controlled/living surface-initiated ATRP of antifouling polymer brushes from gold in PBS and blood sera as a model study for polymer modifications in complex biological media

    Czech Academy of Sciences Publication Activity Database

    Rodriguez-Emmenegger, Cesar; Hasan, E.; Pop-Georgievski, Ognen; Houska, Milan; Brynda, Eduard; Bologna Alles, A.

    2012-01-01

    Roč. 12, č. 4 (2012), s. 525-532 ISSN 1616-5187 R&D Projects: GA AV ČR KAN200670701; GA ČR GAP503/10/0664 Institutional research plan: CEZ:AV0Z40500505 Keywords : antifouling surfaces * atom-transfer radical polymerization (ATRP) * biocompatibility Subject RIV: EE - Microbiology, Virology Impact factor: 3.742, year: 2012

  15. Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

    International Nuclear Information System (INIS)

    Shimizu, Takashi; Ichikawa, Tsuneki

    2005-01-01

    Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon γ-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M n R 1 COOCH(C 6 H 5 )R 2 M n +e - ->M n R 1 COO - + · CH(C 6 H 5 )R 2 M n . The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching

  16. Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Takashi [Nitto Denko Co. LTD., Shimohozumi 1-1-2, Ibaraki, Osaka 567-8680 (Japan); Ichikawa, Tsuneki [Division of Materials Chemistry, Graduate school of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)]. E-mail: ichikawa@eng.hokudai.ac.jp

    2005-07-01

    Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon {gamma}-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M{sub n}R{sub 1}COOCH(C{sub 6}H{sub 5})R{sub 2}M{sub n}+e{sup -}->M{sub n}R{sub 1}COO{sup -}+{sup {center_dot}}CH(C{sub 6}H{sub 5})R{sub 2}M{sub n}. The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching.

  17. Synthesis of Well-defined Amphiphilic Block Copolymers by Organotellurium-Mediated Living Radical Polymerization (TERP).

    Science.gov (United States)

    Kumar, Santosh; Changez, Mohammad; Murthy, C N; Yamago, Shigeru; Lee, Jae-Suk

    2011-10-04

    Low-molecular weight amphiphilic diblock copolymers, polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP), and (P2VP-b-PS) with different block ratios were synthesized for the first time via organotellurium-mediated living radical polymerization (TERP). For both the homo- and block copolymerizations, good agreement between the theoretical, and experimental molecular weights was found with nearly 100% yield in every case. The molecular weight distribution for all the samples ranged between 1.10 and 1.24, which is well below the theoretical lower limit of 1.50 for a conventional free radical polymerization. Furthermore, a very simple approach to producing highly dense arrays of titania nanoparticles (TiO2 ) is presented using a site-selective reaction of titanium tetraisopropoxide within the P2VP domains of micellar film of P2VP-b-PS in toluene through the sol-gel method. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Liquid-crystalline polyesters with end nitroxyl radical and their use in living free-radical polymerization

    Czech Academy of Sciences Publication Activity Database

    Razina, A B.; Sedláková, Zdeňka; Bouchal, Karel; Tenkovtsev, A. V.; Ilavský, Michal

    2002-01-01

    Roč. 44, č. 9 (2002), s. 924-930 ISSN 0965-545X R&D Projects: GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : liquid crystal * polyesters * nitroxyl radical Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.627, year: 2002

  19. Search for heavy long-lived charged particles with the ATLAS detector in pp collisions at {radical}(s)=7 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Aad, G [Fakultaet fuer Mathematik und Physik, Albert-Ludwigs-Universitaet, Freiburg i.Br. (Germany); Abbott, B [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK (United States); Abdallah, J [Institut de Fisica d' Altes Energies and Universitat Autonoma de Barcelona and ICREA, Barcelona (Spain); Abdelalim, A A [Section de Physique, Universite de Geneve, Geneva (Switzerland); Abdesselam, A [Department of Physics, Oxford University, Oxford (United Kingdom); Abdinov, O [Institute of Physics, Azerbaijan Academy of Sciences, Baku (Azerbaijan); Abi, B [Department of Physics, Oklahoma State University, Stillwater, OK (United States); Abolins, M [Department of Physics and Astronomy, Michigan State University, East Lansing, MI (United States); Abramowicz, H [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv (Israel); Abreu, H [LAL, Univ. Paris-Sud and CNRS/IN2P3, Orsay (France); Acerbi, E [INFN Sezione di Milano (Italy); Dipartimento di Fisica, Universita di Milano, Milano (Italy); Acharya, B S [INFN Gruppo Collegato di Udine (Italy); ICTP, Trieste [Italy; Adams, D L [Physics Department, Brookhaven National Laboratory, Upton, NY (United States); Addy, T N [Department of Physics, Hampton University, Hampton, VA (United States); Adelman, J [Department of Physics, Yale University, New Haven, CT (United States); Aderholz, M [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Muenchen (Germany); Adomeit, S [Fakultaet fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Muenchen (Germany); Adragna, P [Department of Physics, Queen Mary University of London, London (United Kingdom); Adye, T [Particle Physics Department, Rutherford Appleton Laboratory, Didcot (United Kingdom); Aefsky, S [Department of Physics, Brandeis University, Waltham, MA (United States)

    2011-09-20

    A search for long-lived charged particles reaching the muon spectrometer is performed using a data sample of 37 pb{sup -1} from pp collisions at {radical}(s)=7 TeV collected by the ATLAS detector at the LHC in 2010. No excess is observed above the estimated background. Stable {tau}{sup -tilde} sleptons are excluded at 95% CL up to a mass of 136 GeV, in GMSB models with N{sub 5}=3, m{sub messenger}=250 TeV, sign({mu})=1 and tan{beta}=5. Electroweak production of sleptons is excluded up to a mass of 110 GeV. Gluino R-hadrons in a generic interaction model are excluded up to masses of 530 GeV to 544 GeV depending on the fraction of R-hadrons produced as g{sup -tilde} -balls.

  20. Long-lived radicals produced by γ-irradiation or vital activity in plants, animals, cells, and protein solution: their observation and inhomogeneous decay dynamics

    International Nuclear Information System (INIS)

    Miyazaki, Tetsuo; Morikawa, Akiyuki; Kumagai, Jun; Ikehata, Masateru; Koana, Takao; Kikuchi, Shoshi

    2002-01-01

    Long-lived radicals produced by γ-irradiation or vital activity in plants, animals, cells, and protein (albumin) solution were studied by electron spin resonance spectroscopy. Long-lived radicals produced by vital activity exist in biological systems, such as plants, animals, and cells, in the range of 0.1-20 nmol g -1 . Since vital organs keep the radicals at a constant concentration, the radicals are probably related to life conservation. Long-lived radicals are also produced by γ-irradiation of cells or protein solution. The radicals decay after death of living things or after γ-irradiation. We found that the decay dynamics in all biological systems can be expressed by the same kinetic equation of an inhomogeneous reaction

  1. Acrylonitrile-Butadiene Rubber (NBR) Prepared via Living/Controlled Radical Polymerization (RAFT).

    Science.gov (United States)

    Kaiser, Andreas; Brandau, Sven; Klimpel, Michael; Barner-Kowollik, Christopher

    2010-09-15

    In the current work we present results on the controlled/living radical copolymerization of acrylonitrile (AN) and 1,3-butadiene (BD) via reversible addition fragmentation chain transfer (RAFT) polymerization techniques. For the first time, a solution polymerization process for the synthesis of nitrile butadiene rubber (NBR) via the use of dithioacetate and trithiocarbonate RAFT agents is described. It is demonstrated that the number average molar mass, $\\overline M _{\\rm n} $, of the NBR can be varied between a few thousand and 60 000 g · mol(-1) with polydispersities between 1.2 and 2.0 (depending on the monomer to polymer conversion). Excellent agreement between the experimentally observed and the theoretically expected molar masses is found. Detailed information on the structure of the synthesized polymers is obtained by variable analytical techniques such as infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, and electrospray ionization-mass spectrometry (ESI-MS). Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Impact of high resolution land surface initialization in Indian summer ...

    Indian Academy of Sciences (India)

    The direct impact of high resolution land surface initialization on the forecast bias in a regional climate model in recent years ... surface initialization using a regional climate model. ...... ization of the snow field in a cloud model; J. Clim. Appl.

  3. Strong resistance of Arabidopsis thaliana and Raphanus sativus seeds for ionizing radiation as studied by ESR, ENDOR, ESE spectroscopy and germination measurement: Effect of long-lived and super-long-lived radicals

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, Jun E-mail: kumagai@apchem.nagoya-u.ac.jp; Katoh, Hiromi; Kumada, Takayuki; Tanaka, Atsushi; Tano, Shigemitsu; Miyazaki, Tetsuo

    2000-01-01

    Resistance of seeds for ionizing radiation effects on Arabidopsis thaliana and Raphanus sativus seeds were investigated by ESR, ENDOR, ESE spectroscopy and germination measurement. Two types of free radicals, such as long-lived (LL) and super-long-lived (SL) radicals, were produced by the {gamma}-irradiation in the seeds. More than 90% of the 1 kGy-irradiated-seeds can germinate probably by decreasing the LL radicals by absorbing water. 10 kGy-irradiated-seeds cannot germinate at all probably due to the existence of significant amounts of the SL radicals even after absorbing water. (author)

  4. Single-electron transfer living radical copolymerization of SWCNT-g-PMMA via graft from approach

    Czech Academy of Sciences Publication Activity Database

    Jaisankar, S. N.; Haridharan, N.; Murali, A.; Ponyrko, Sergii; Špírková, Milena; Mandal, A. B.; Matějka, Libor

    2014-01-01

    Roč. 55, č. 13 (2014), s. 2959-2966 ISSN 0032-3861 R&D Projects: GA ČR GAP108/12/1459 Institutional support: RVO:61389013 Keywords : single electron transfer * single-walled carbon nanotubes * controlled radical polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.562, year: 2014

  5. Studies of short-lived radicals in the. gamma. -irradiated aqueous solution of uridine-5'-monophosphate by the spin-trapping method and the liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Kominami, S [Hiroshima Univ. (Japan); Rokushika, S; Hatano, H

    1976-12-01

    An aerated aqueous solution of uridine-5'-monophosphate was ..gamma..-irradiated with 2-methyl-2-nitrosopropane as a spin-trapping reagent. Liquid chromatography was applied to separate the stable nitroxide radicals in the irradiated solution. The radicals were detected by U.V. and e.s.r. spectrometry. The e.s.r. detection showed four peaks in the chromatogram. The orcinol method for detection of the residual sugar moieties was applied before and after reduction of the base to determine the existence of the 5,6-double bond for the molecules in each fraction. From the combined results of the e.s.r. and orcinol methods, the short-lived radicals which were trapped by 2-methyl-2-nitrosopropane were identified as radicals of N-1 and C-6 positions of the base moiety and t-butyl radicals which was the radiolytic product of the trapping reagent.

  6. Reaction of long-lived radicals and vitamin C in γ-irradiated mammalian cells and their model system at 295 K. Tunneling reaction in biological system

    International Nuclear Information System (INIS)

    Matsumoto, Takuro; Miyazaki, Tetsuo; Kosugi, Yoshio; Kumada, Takayuki; Koyama, Sinji; Kodama, Seiji; Watanabe, Masami.

    1996-01-01

    When golden hamster embryo (GHE) cells or concentrated albumin solution (0.1 kg dm -3 ) that is a model system of cells is irradiated with γ-rays at 295 K, organic radicals produced can be observed by ESR. The organic radicals survive at both 295 K and 310 K for such a long time as 20 hr. The long-lived radicals in GHE cells and the albumin solution react with vitamin C by the rate constants of 0.007 dm 3 mol -1 s -1 and 0.014 dm 3 mol -1 s -1 , respectively. The long-lived radicals in human cells cause gene mutation, which is suppressed by addition of vitamin C. The isotope effect on the rate constant (k) for the reaction of the long-lived radicals and vitamin C has been studied in the albumin solution by use of protonated vitamin C and deuterated vitamin C. The isotope effect (k H /k D ) was more than 20-50 and was interpreted in terms of tunneling reaction. When GHE cells or the aqueous albumin solution (0.1 kg dm -3 ) is irradiated with γ-rays at 295 K, organic radicals produced survive for more than 24 hr at room temperature. Very recently we have found that vitamin C reacts with the long-lived organic radicals in the γ-irradiated albumin solution at high concentration of 0.1 kg dm -3 by the rate constant of 0.014 dm 3 mol -1 s -1 . Since most of reactions in biological systems including the reaction of vitamin C are a transfer of a hydrogen atom or a proton that has a large wave character, it is generally expected that the tunneling reaction may play an important role in biological systems at room temperature. The studies of isotope effects on reactions will give an information on the contribution of tunneling reaction. (J.P.N.)

  7. Reaction of long-lived radicals and vitamin C in γ-irradiated mammalian cells and their model system at 295 K. Tunneling reaction in biological system

    International Nuclear Information System (INIS)

    Matsumoto, Takuro; Kumada, Takayuki; Kodama, Seiji; Watanabe, Masami

    1997-01-01

    When golden hamster embryo (GHE) cells or concentrated albumin solution (0.1 kg dm -3 ), that is a model system of cells, is irradiated with γ-rays at 295 K, organic radicals produced can be observed by ESR. The organic radicals survive at both 295 and 310 K for as long as 20 h. The long-lived radicals in GHE cells and the albumin solution react with vitamin C by the rate constants of 0.007 dm 3 mol -1 s -1 and 0.014 dm 3 mol -1 s -1 , respectively. The long-lived radicals in human cells cause gene mutation, which is suppressed by the addition of vitamin C. The isotope effect on the rate constant (κ) for the reaction of the long-lived radicals and vitamin C has been studied in the albumin solution by use of protonated vitamin C and deuterated vitamin C. The isotope effect (κ H /κ D ) was more than 20 ∼ 50 and was interpreted in terms of tunnelling reaction. (author)

  8. Nitroxide free radical clearance in the live rat monitored by radio-frequency CW-EPR and PEDRI

    International Nuclear Information System (INIS)

    Alecci, Marcello; Seimenis, Ioannis; McCallum, Stephen J.; Lurie, David J.; Foster, Margaret A.

    1998-01-01

    The use of RF (100 to 300 MHz) PEDRI and CW-EPR techniques allows the in vivo study of large animals such as whole rats and rabbits. Recently a PEDRI instrument was modified to also allow CW-EPR spectroscopy with samples of similar size and under the same experimental conditions. In the present study, this CW-EPR and PEDRI apparatus was used to assess the feasibility of the detection of a pyrrolidine nitroxide free radical (2,2,5,5,-tetramethylpyrrolidine-1-oxyl-3-carboxylic acid, PCA) in the abdomen of rats. In particular, we have shown that after the PCA administration (4 mmol kg -1 b.w.): (i) the PCA EPR linewidth does not show line broadening due to concentration effects; (ii) a similar PCA up-take phase is observed by EPR and PEDRI; and (iii) the PCA half-lives in the whole abdomen of rats measured with the CW-EPR (T 1/2 =26±4 min, mean±sd, n=10) and PEDRI (T 1/2 =29±4 min, mean±sd, n=4) techniques were not significantly different (p>0.05). These results show, for the first time, that information about PCA pharmacokinetics obtained by CW-EPR is the same as that from PEDRI under the same experimental conditions. (author)

  9. Enhanced protein retention on poly(caprolactone) via surface initiated polymerization of acrylamide

    International Nuclear Information System (INIS)

    Ma, Yuhao; Cai, Mengtan; He, Liu; Luo, Xianglin

    2016-01-01

    Graphical abstract: - Highlights: • Dense package of poly(acrylamide) on poly(caprolactone) surface was achieved by surface-initiated atom transfer radical polymerization. • Poly(acrylamide) grafted surface exhibited high protein retention ability. • Loaded protein was resistant to detachment and maintained its structure without denaturation. - Abstract: To enhance the biocompatibility or extend the biomedical application of poly(caprolactone) (PCL), protein retention on PCL surface is often required. In this study, poly(acrylamide) (PAAm) brushes were grown from PCL surface via surface-initiated atom transfer radical polymerization (SI-ATRP) and served as a protein-capturing platform. Grafted PAAm was densely packed on surface and exhibited superior protein retention ability. Captured protein was found to be resistant to washing under detergent environment. Furthermore, protein structure after being captured was investigated by circular dichroism (CD) spectroscopy, and the CD spectra verified that secondary structure of captured proteins was maintained, indicating no denaturation of protein happened for retention process.

  10. "'And They Lived Happily Ever After": The Fairy Tale of Radical Constructivism and Von Glasersfeld's Ethical Disengagement

    Science.gov (United States)

    d'Agnese, Vasco

    2015-01-01

    Is von Glasersfeld's constructivism actually radical? In this article, I respond to this question by analyzing von Glasersfeld's main works. I argue that the essential theoretical move of radical constructivism--namely the assertion that reality is the construction of a human mind that only responds to the subjective perception of "what…

  11. Patterning of gold substrates by surface-initiated polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, D.J. [Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901-4409 (United States)

    2003-09-01

    The design and synthesis of durable and functional organic coatings is an important topic in contemporary polymer science. The well-defined patterning of inorganic substrates is highlighted with an emphasis on planar gold. New advances in contact printing and surface initiated polymerization promise unprecedented control of the polymer architecture in the micrometer and nanometer range. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  12. Hydrophilization of Poly(ether ether ketone) Films by Surface-initiated Atom Transfer Radical Polymerization

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Eskimergen, Rüya; Burkrinsky, J.T.

    2008-01-01

    and confirmed by ATR FTIR, water contact ang;le, and Thermal Gravimetric Analysis (TGA). The surface topography was evaluated by "Atomic Force Microscopy (AFM). X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the degree of functionalization. The performed modification allowed for successful...

  13. Protein repellent hydrophilic grafts prepared by surface-initiated atom transfer radical polymerization from polypropylene

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Eskimergen, Rüya

    2012-01-01

    with Attenuated Total Reflectance (ATR) Fourier Transform Infrared (FTIR) spectroscopy and Water Contact Angle (WCA) measurements. Confocal fluorescence microscopy of modified and unmodified substrates immersed in labelled insulin aspart showed superior repulsion of this protein for the poly(PEGMA) grafts, due...

  14. Surface-Initiated Atom Transfer Radical Polymerization from Electrospun Mats: An Alternative to Nafion

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Dimitrov, Ivaylo; Tynelius, Oskar

    2017-01-01

    , respectively. The membrane morphology is probedby scanning electron microscopy. A membrane with protonconductivity as high as 100 mS cm−1 is obtained. Long-termdurability study in direct methanol fuel cells is conducted forover 1500 h demonstrating the viability of this novel facileapproach....

  15. Surface-Initiated Polymerization by Means of Novel, Stable, Non-Ester-Based Radical Initiator

    Czech Academy of Sciences Publication Activity Database

    Bain, E. D.; Dawes, K.; Ozcam, A. E.; Hu, X.; Gorman, C. B.; Šrogl, Jiří; Genzer, J.

    2012-01-01

    Roč. 45, č. 9 (2012), s. 3802-3815 ISSN 0024-9297 Institutional support: RVO:61388963 Keywords : self-assembled monolayers * poly(acrylic acid) brushes * thermoresponsive polymer Subject RIV: CC - Organic Chemistry Impact factor: 5.521, year: 2012

  16. Design of UV-absorbing PVDF membrane via surface-initiated AGET ATRP

    Science.gov (United States)

    Dong, Li; Liu, Xiangdong; Xiong, Zhengrong; Sheng, Dekun; Zhou, Yan; Lin, Changhong; Yang, Yuming

    2018-03-01

    Herein, PVDF membranes with excellent UV-absorbing property were first synthesized through grafting the polymerizable low-molecular-weight organic UV-absorber 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) onto α-bromoester-functionalized PVDF membranes via the surface-initiated activator generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The surface initiators were immobilized by the reaction between 2-bromoisobutyryl bromide (BIBB) and the hydroxylated PVDF membranes. PVDF-g-PBPMA membranes with different grafting densities were obtained by tuning the polymerization time and the modified membranes were characterized by 1H-NMR, FT-IR, XPS, SEM, UV-vis Spectrophotometer, TGA and DSC. The experimental results indicated that PBPMA chains were successfully introduced onto PVDF membranes. Most importantly, the PVDF-g-PBPMA membranes exhibited outstanding UV-shielding property. UV-vis transmittance spectra showed that most UV light below 360 nm could be absorbed by PVDF-g-PBPMA membranes and the whole UV light region (200-400 nm) can be blocked with the reaction time increased.

  17. Surface modification of hydroxyapatite with poly(methyl methacrylate) via surface-initiated ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yan; Zhang Xi; Yan Jinliang; Xiao Yan [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Lang Meidong, E-mail: mdlang@ecust.edu.cn [Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China)

    2011-05-01

    This article describes the fabrication of hydroxyapatite (HAP) nanocomposites grafted with poly(methyl methacrylate) (PMMA). Surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was carried out from hydroxyapatite particles derivatized with ATRP initiators. The structure and properties of the nanocomposites were investigated by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), differential scanning calorimeter (DSC) measurements, and contact angle analyses. TGA was used to estimate the grafting density of ATRP initiators (0.49 initiator/nm{sup 2}) and the amount of grafted PMMA on the HAP surface. The contact angle analyses indicated that grafting PMMA onto the HAP surface dramatically increased the hydrophobicity of the surface. Moreover, the HAP nanocomposites showed excellent dispersibility in both aqueous solution and organic solvent.

  18. Surface modification of hydroxyapatite with poly(methyl methacrylate) via surface-initiated ATRP

    International Nuclear Information System (INIS)

    Wang Yan; Zhang Xi; Yan Jinliang; Xiao Yan; Lang Meidong

    2011-01-01

    This article describes the fabrication of hydroxyapatite (HAP) nanocomposites grafted with poly(methyl methacrylate) (PMMA). Surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was carried out from hydroxyapatite particles derivatized with ATRP initiators. The structure and properties of the nanocomposites were investigated by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), differential scanning calorimeter (DSC) measurements, and contact angle analyses. TGA was used to estimate the grafting density of ATRP initiators (0.49 initiator/nm 2 ) and the amount of grafted PMMA on the HAP surface. The contact angle analyses indicated that grafting PMMA onto the HAP surface dramatically increased the hydrophobicity of the surface. Moreover, the HAP nanocomposites showed excellent dispersibility in both aqueous solution and organic solvent.

  19. Synthesis of triblock and random copolymers of 4- acetoxystyrene and styrene by living atom transfer radical polymerization

    DEFF Research Database (Denmark)

    Gao, Bo; Chen, Xianyi; Ivan, Bela

    1997-01-01

    Triblock copolymers containing polystyrene (PSt) and poly(4-acetoxystyrene) (PAcOSt) segments have been prepared by atom transfer radical polymerization (ATRP). In the first step one of the two monomers was polymerized in bulk using the initiating system alpha,alpha'-dibromo-p-xylene/CuBr/2,2'-bi...

  20. Improving the drug delivery characteristics of graphene oxide based polymer nanocomposites through the “one-pot” synthetic approach of single-electron-transfer living radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Peng; Liu, Meiying; Tian, Jianwen; Deng, Fengjie [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wang, Ke [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China); Xu, Dazhuang [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Liu, Liangji [Affiliated Hospital of Jiangxi University of Traditional Chinese Medicine, Nanchang 330006 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China)

    2016-08-15

    Graphical abstract: The PEGylated graphene oxides with high water dispersibility, good biocompatibility as well as high drug loading capability were fabricated via “one-pot” SET-LRP. - Highlights: • Surface modification of graphene oxide with polymers. • One-pot single-electron-transfer living radical polymerization. • Improving drug delivery characteristics. • The synthetic approach is rather simple, universal and effective. - Abstract: Graphene oxide (GO) based polymer nanocomposites have attracted extensive research interest recently for their outstanding physicochemical properties and potential applications. However, surface modification of GO with synthetic polymers has demonstrated to be trouble for most polymerization procedures are occurred under non-aqueous solution, which will in turn lead to the restacking of GO. In this work, a facile and efficient “one-pot” strategy has been developed for surface modification of GO with synthetic polymers through single-electron-transfer living radical polymerization (SET-LRP). The GO based polymer nanocomposites were obtained via SET-LRP in aqueous solution using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the monomer and 11-bromoundecanoic acid as the initiator, which could be effectively adsorbed on GO through hydrophobic interaction. The successful preparation of GO based polymer nanocomposites was confirmed by a series of characterization techniques such as {sup 1}H nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The resultant products exhibit high water disperisibility, excellent biocompatibility and high efficient drug loading capability, making these PEGylated GO nanocomposites promising candidates for biomedical applications.

  1. Surface Initiated Polymerizations via e-ATRP in Pure Water

    Directory of Open Access Journals (Sweden)

    Seyed Schwan Hosseiny

    2013-10-01

    Full Text Available Here we describe the combined process of surface modification with electrochemical atom transfer radical polymerization (e-ATRP initiated from the surface of a modified gold-electrode in a pure aqueous solution without any additional supporting electrolyte. This approach allows for a very controlled growth of the polymer chains leading towards a steady increase in film thickness. Electrochemical quartz crystal microbalance displayed a highly regular increase in surface confined mass only after the addition of the pre-copper catalyst which is reduced in situ and transformed into the catalyst. Even after isolation and washing of the modified electrode surface, reinitiation was achieved with retention of the controlled electrochemical ATRP reaction. This reinitiation after isolation proves the livingness of the polymerization. This approach has interesting potential for smart thin film materials and offers also the possibility of post-modification via additional electrochemical induced reactions.

  2. PNIPAAm-grafted thermoresponsive microcarriers: Surface-initiated ATRP synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Çakmak, Soner [Nanotechnology and Nanomedicine Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey); Çakmak, Anıl S. [Bioengineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey); Gümüşderelioğlu, Menemşe, E-mail: menemse@hacettepe.edu.tr [Nanotechnology and Nanomedicine Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey); Bioengineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey); Chemical Engineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey)

    2013-07-01

    In this study, we developed novel thermoresponsive microcarriers as a powerful tool for cell culture and tissue engineering applications. For this purpose, two types of commercially available spherical microparticles (approximately 100 μm in diameter), dextran-based Sephadex® and vinyl acetate-based VA-OH (Biosynth®), were used and themoresponsive poly(N-isopropylacrylamide) (PNIPAAm) was grafted to the beads' surfaces by surface-initiated atom transfer radical polymerization (SI-ATRP). Initially, hydroxyl groups of microbeads were reacted with 2-bromopropionyl bromide to form ATRP macroinitiator. Then, NIPAAm was successfully polymerized from the initiator attached microbeads by ATRP with CuBr/2,2′-dipyridyl, catalyst complex. Furthermore, grafted and ungrafted microbeads were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscope (SEM), atomic force microscopy (AFM) and electron spectroscopy for chemical analysis (ESCA). The results of characterization studies confirmed that PNIPAAm was successfully grafted onto both dextran and vinyl acetate-based beads by means of ATRP reaction and thus, grafted microbeads gained thermoresponsive characteristics which will be evaluated for cell harvesting in further studies. Highlights: • PNIPAAm was grafted to the hydroxyl group carrying polymer beads by SI-ATRP. • Dex-g-PNIPAAm and VA-OH-g-PNIPAAm beads exhibited thermoresponsive characteristics. • They are appropriate candidates for microcarrier-facilitated cell cultures.

  3. PNIPAAm-grafted thermoresponsive microcarriers: Surface-initiated ATRP synthesis and characterization

    International Nuclear Information System (INIS)

    Çakmak, Soner; Çakmak, Anıl S.; Gümüşderelioğlu, Menemşe

    2013-01-01

    In this study, we developed novel thermoresponsive microcarriers as a powerful tool for cell culture and tissue engineering applications. For this purpose, two types of commercially available spherical microparticles (approximately 100 μm in diameter), dextran-based Sephadex® and vinyl acetate-based VA-OH (Biosynth®), were used and themoresponsive poly(N-isopropylacrylamide) (PNIPAAm) was grafted to the beads' surfaces by surface-initiated atom transfer radical polymerization (SI-ATRP). Initially, hydroxyl groups of microbeads were reacted with 2-bromopropionyl bromide to form ATRP macroinitiator. Then, NIPAAm was successfully polymerized from the initiator attached microbeads by ATRP with CuBr/2,2′-dipyridyl, catalyst complex. Furthermore, grafted and ungrafted microbeads were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscope (SEM), atomic force microscopy (AFM) and electron spectroscopy for chemical analysis (ESCA). The results of characterization studies confirmed that PNIPAAm was successfully grafted onto both dextran and vinyl acetate-based beads by means of ATRP reaction and thus, grafted microbeads gained thermoresponsive characteristics which will be evaluated for cell harvesting in further studies. Highlights: • PNIPAAm was grafted to the hydroxyl group carrying polymer beads by SI-ATRP. • Dex-g-PNIPAAm and VA-OH-g-PNIPAAm beads exhibited thermoresponsive characteristics. • They are appropriate candidates for microcarrier-facilitated cell cultures

  4. Hyperoxia exposure induced hormesis decreases mitochondrial superoxide radical levels via Ins/IGF-1 signaling pathway in a long-lived age-1 mutant of Caenorhabditis elegans

    International Nuclear Information System (INIS)

    Yanase, Sumino; Ishii, Naoaki

    2008-01-01

    The hormetic effect, which extends the lifespan by various stressors, has been confirmed in Caenorhabditis elegans (C. elegans). We have previously reported that oxidative stress resistance in a long-lived mutant age-1 is associated with the hormesis. In the age-1 allele, which activates an insulin/insulin-like growth factor-1 (Ins/IGF-1) signaling pathway, the superoxide dismutase (SOD) and catalase activities increased during normal aging. We now demonstrate changes in the mitochondrial superoxide radical (O 2 - ) levels of the hormetic conditioned age-related strains. The O 2 - levels in age-1 strain significantly decreased after intermittent hyperoxia exposure. On the other hand, this phenomenon was not observed in a daf-16 null mutant. This hormesis-dependent reduction of the O 2 - levels was observed even if the mitochondrial Mn-SOD was experimentally reduced. Therefore, it is indicated that the hormesis is mediated by events that suppress the mitochondrial O 2 - production. Moreover, some SOD gene expressions in the hormetic conditioned age-1 mutant were induced over steady state messenger ribonucleic acid (mRNA) levels. These data suggest that oxidative stress-inducible hormesis is associated with a reduction of the mitochondrial O 2 - production by activation of the antioxidant system via the Ins/IGF-1 signaling pathway. (author)

  5. TEMPO addition into pre-irradiated fluoropolymers and living-radical graft polymerization of styrene for preparation of polymer electrolyte membranes

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, Shin-ichi, E-mail: sawada.shinnichi@jaea.go.j [Conducting Polymer Materials Research Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Department of Nuclear Engineering and Management, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Suzuki, Akihiro; Terai, Takayuki [Department of Nuclear Engineering and Management, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Maekawa, Yasunari, E-mail: maekawa.yasunari@jaea.go.j [Conducting Polymer Materials Research Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2010-04-15

    We prepared proton exchange membranes (PEMs) by 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-mediated living-radical graft polymerization (LRGP) of styrene into fluoropolymer films and subsequent sulfonation. Poly(vinylidene fluoride) (PVDF) and poly(ethylene-co-tetrafluoroethylene) (ETFE) films were first irradiated and then treated with TEMPO solutions in various solvents. TEMPO addition was confirmed by the test of styrene grafting into TEMPO-treated films at 60 deg. C, at which the LRGP never proceeds. This test enabled us to differentiate the LRGP from the conventional graft polymerization. In order to gain a deep insight about TEMPO-addition reaction, the TEMPO-penetration behavior into the base polymer films was examined by a permeation experiment and computer simulation. Xylene and dioxane were appropriate solvents for the complete introduction of TEMPO into PVDF and ETFE films, respectively. Then, the LRGP of styrene was performed based on the fully TEMPO-capped films at 125 deg. C with various solvents. By using an alcoholic solvent, the degree of grafting was enhanced and it reached a maximum of 38%. This grafted film was sulfonated to prepare a PEM showing an ion exchange capacity of 2.2 meq/g and proton conductivity of 1.6x10{sup -1} S/cm.

  6. 4-Amino-3H-pyrimidin-2-one ('isocytosine') is a short-lived non-radical intermediate formed in the pulse radiolysis of cytosine in aqueous solution

    International Nuclear Information System (INIS)

    Nien Schuchmann, Man; Naumov, Sergej; Schuchmann, Heinz-Peter; Sonntag, Justus von; Sonntag, Clemens von

    2005-01-01

    In the pulse radiolysis of 2'-deoxycytidine (dCyd) in N 2 O-saturated solutions containing 0.5M tertiary butanol to completely scavenge the water radicals, a short-lived intermediate (λmax=287nm) is observed by UV spectroscopy which is attributed to dCydH + , generated in the reaction of dCyd with H + formed during the pulse. By reacting with OH - , which is formed in the pulse in amounts matching that of H + , this intermediate disappears in the μs time range without a change of the spectrum. Similarly, cytosine (Cyt) gives rise to CytH + which, in contrast, in part transforms into another species (λmax=286nm) which can be assigned to isocytosine 1, 4-amino-3H-pyrimidin-2-one, a tautomer of Cyt which is formed by two routes (i) deprotonation of CytH + at N(1) by OH - and (ii) deprotonation of Cyt and reprotonation of the Cyt anion by water at N(3). Compared to Cyt, 1 is richer in Gibbs' free enthalpy by 14kJmol -1 . Its presence in low equilibrium concentrations has also been observed by conventional UV spectroscopy, making use of the increase of its equilibrium concentration with increasing temperature. From these data, an absorption coefficient of 3.3x10 4 dm 3 mol -1 cm -1 at 286nm has been calculated. Supporting quantum chemical calculations are also reported

  7. Violent Radicalization in Europe

    DEFF Research Database (Denmark)

    Dalgaard-Nielsen, Anja

    2010-01-01

    When, why, and how do people living in a democracy become radicalized to the point of being willing to use or directly support the use of terrorist violence against fellow citizens? This question has been at the center of academic and public debate over the past years as terrorist attacks...... within this field and to answer the question: From an empirical point of view, what is known and what is not known about radicalization connected to militant Islamism in Europe?...

  8. Functional copolymer/organo-MMT nanoarchitectures. VI. Synthesis and characterization of novel nanocomposites by interlamellar controlled/living radical copolymerization via preintercalated RAFT-agent/organoclay complexes.

    Science.gov (United States)

    Rzayev, Zakir M O; Söylemez, A Ernur

    2011-04-01

    We have developed a new approach for the synthesis of polymer nanocomposites using a bifunctional reversible addition-fragmentation chain transfer (RAFT) agent, two types of organo-montmorillonites, such as a non-reactive dimethyldodecyl ammonium (DMDA)-MMT and a reactive octadecylamine (ODA)-MMT organoclays, and a radical initiator. The method includes the following stages: (1) synthesis of RAFT intercalated O-MMTs by a physical or chemical interaction of the RAFT agent having two pendant carboxylic groups [S,S-bis(alpha,alpha'-dimethyl-alpha"-acetic acid)trithiocarbonate] with surface alkyl amines of O-MMT containing tertiary ammonium cation or primary amine groups through strong H-bonding and complexing/amidization reactions, respectively, and (2) utilization of these well-dispersed and intercalated RAFT ... O-MMT complexes and their amide derivatives as new modified RAFT agents in radical-initiated interlamellar controlled/living copolymerization of itaconic acid (IA)-n-butylmethacrylate (BMA) monomer pair. The structure and compositions of the synthesized RAFT ... O-MMT complexes and functional copolymer/O-MMT hybrids were confirmed by FTIR, XRD, thermal (DSC-TGA), SEM and TEM morphology analyses. It was demonstrated that the degree of interaction/exfoliation, morphology and thermal behavior of nanocomposites significantly depended on the type of organoclay and in situ interaction, as well as on the content of flexible butyl-ester linkages as a internal plasticizer. The results of the comparative analysis of the nanocomposites structure-composition-property relations show that the functional copolymer-organoclay hybrids prepared with reactive RAFT ... ODA-MMT complex and containing a combination of partially intercalated and predominantly exfoliated nano-structures exhibit relatively higher thermal stability and fine dispersed morphology. These effects were explained by in situ interfacial chemical reactions through amidization of RAFT with surface alkyl amine

  9. Preparation and controlled drug delivery applications of mesoporous silica polymer nanocomposites through the visible light induced surface-initiated ATRP

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Long; Liu, Meiying; Mao, Liucheng; Xu, Dazhuang; Wan, Qing; Zeng, Guangjian; Shi, Yingge [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wen, Yuanqing, E-mail: m18600788382@163.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and The Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China)

    2017-08-01

    Graphical abstract: A novel strategy for surface PEGylation of mesoporous silica nanoparticles was developed based on the light induced surface-initiated atom transfer radical polymerization. - Highlights: • Surface modification of silica nanoparticles through light induced surface-initiated ATRP. • MSNs-NH{sub 2}-poly(IA-co-PEGMA) nanocomposites show high water dispersity. • MSNs-NH{sub 2}-poly(IA-co-PEGMA) nanocomposites are promising for biomedical applications. • The light induced ATRP possesses many advantages as compared with traditional ATRP. - Abstract: The mesoporous materials with large pore size, high specific surface area and high thermal stability have been widely utilized in a variety of fields ranging from environmental remediation to separation and biomedicine. However, surface modification of these silica nanomaterials is required to endow novel properties and achieve better performance for most of these applications. In this work, a new method has been established for surface modification of mesoporous silica nanoparticles (MSNs) that relied on the visible light induced atom transfer radical polymerization (ATRP). In the procedure, the copolymers composited with itaconic acid (IA) and poly(ethylene glycol)methyl acrylate (PEGMA) were grafted from MSNs using IA and PEGMA as the monomers and 10-Phenylphenothiazine(PTH) as the organic catalyst. The successful preparation of final polymer nanocomposites (named as MSNs-NH{sub 2}-poly(IA-co-PEGMA)) were evidenced by a series of characterization techniques. More importantly, the anticancer agent cisplatin can be effectively loaded on MSNs-NH{sub 2}-poly(IA-co-PEGMA) and controlled release it from the drug-loading composites with pH responsive behavior. As compared with conventional ATRP, the light induced surface-initiated ATRP could also be utilized for preparation of various silica polymer nanocomposites under rather benign conditions (e.g. absent of transition metal ions, low polymerization

  10. Preparation of polymeric silica composites through polydopamine-mediated surface initiated ATRP for highly efficient removal of environmental pollutants

    International Nuclear Information System (INIS)

    Huang, Qiang; Liu, Meiying; Wan, Qing; Jiang, Ruming; Mao, Liucheng; Zeng, Guangjian; Huang, Hongye; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2017-01-01

    In this study, we developed a new procedure to prepare monodispersed functionalized SiO_2 (SiO_2-PDA-PDMC) composites via mussel inspired chemistry and surface initiated atom transfer radical polymerization (SI-ATRP). Samples were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) measurements. TEM results showed that spherical morphology was unchanged after the functionalization. FT-IR results confirmed the successful modification with polydopamine (PDA) and the presence of poly-([2-(Methacryloyloxy) ethyl] trimethylammonium chloride) (PDMC) layer on the surface of SiO_2 spheres. TGA data showed that the PDMC account for about 12.12 wt% in the sample of SiO_2-PDA-PDMC composites. The XPS analysis further confirmed the existence of PDMC on the surface of SiO_2-PDA-PDMC composites. The obtained SiO_2-PDA-PDMC composites were used as adsorbent for the removal of Congo red (CR) from aqueous solution to evaluate the performance in environment application. The effect of contact time, solution pH, initial CR concentration and temperature on the adsorption of CR onto SiO_2-PDA-PDMC composites was investigated. Adsorption results demonstrated that adsorption of CR onto SiO_2-PDA-PDMC composites was a fast and efficient process. The adsorption equilibrium reached within 60 min, and the adsorption process followed the pseudo-second-order model. The experimental data of isotherms were better described by the Freundlich model. Thermodynamic study depicted the endothermic nature of adsorption and the process was spontaneous. Results from the effect of solution pH on the CR adsorption showed that the acidic condition favors the adsorption and provided evidence for the contribution of PDMC on the SiO_2-PDA-PDMC composites in the removal of CR. This study suggests SiO_2-PDA-PDMC composites can be developed as a new adsorbent for the removal of

  11. Preparation of polymeric silica composites through polydopamine-mediated surface initiated ATRP for highly efficient removal of environmental pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qiang; Liu, Meiying; Wan, Qing; Jiang, Ruming; Mao, Liucheng; Zeng, Guangjian; Huang, Hongye; Deng, Fengjie [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing 100084 (China)

    2017-06-01

    In this study, we developed a new procedure to prepare monodispersed functionalized SiO{sub 2} (SiO{sub 2}-PDA-PDMC) composites via mussel inspired chemistry and surface initiated atom transfer radical polymerization (SI-ATRP). Samples were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) measurements. TEM results showed that spherical morphology was unchanged after the functionalization. FT-IR results confirmed the successful modification with polydopamine (PDA) and the presence of poly-([2-(Methacryloyloxy) ethyl] trimethylammonium chloride) (PDMC) layer on the surface of SiO{sub 2} spheres. TGA data showed that the PDMC account for about 12.12 wt% in the sample of SiO{sub 2}-PDA-PDMC composites. The XPS analysis further confirmed the existence of PDMC on the surface of SiO{sub 2}-PDA-PDMC composites. The obtained SiO{sub 2}-PDA-PDMC composites were used as adsorbent for the removal of Congo red (CR) from aqueous solution to evaluate the performance in environment application. The effect of contact time, solution pH, initial CR concentration and temperature on the adsorption of CR onto SiO{sub 2}-PDA-PDMC composites was investigated. Adsorption results demonstrated that adsorption of CR onto SiO{sub 2}-PDA-PDMC composites was a fast and efficient process. The adsorption equilibrium reached within 60 min, and the adsorption process followed the pseudo-second-order model. The experimental data of isotherms were better described by the Freundlich model. Thermodynamic study depicted the endothermic nature of adsorption and the process was spontaneous. Results from the effect of solution pH on the CR adsorption showed that the acidic condition favors the adsorption and provided evidence for the contribution of PDMC on the SiO{sub 2}-PDA-PDMC composites in the removal of CR. This study suggests SiO{sub 2}-PDA-PDMC composites can be

  12. Polystyrene/magnesium hydroxide nanocomposite particles prepared by surface-initiated in-situ polymerization

    International Nuclear Information System (INIS)

    Liu Hui; Yi Jianhong

    2009-01-01

    In order to avoid their agglomeration and incompatibility with hydrophobic polystyrene substrate, magnesium hydroxide nanoparticles were encapsulated by surface-initiated in-situ polymerization of styrene. The process contained two steps: electrostatic adsorption of initiator and polymerization of monomer on the surface of magnesium hydroxide. It was found that high adsorption ratio in the electrostatic adsorption of initiator could be attained only in acidic region, and the adsorption belonged to typical physical process. Compared to traditional in-situ polymerization, higher grafting ratio was obtained in surface-initiated in-situ polymerization, which can be attributed to weaker steric hindrance. Both Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) indicated that polystyrene/magnesium hydroxide nanocomposite particles had been successfully prepared by surface-initiated in-situ polymerization. The resulting samples were also analyzed and characterized by means of contact angle testing, dispersibility evaluation and thermogravimetric analysis

  13. HPLC-ESR techniques for detection of complex trapped radicals

    International Nuclear Information System (INIS)

    Tu Tiecheng; Dong Jirong; Lin Nianyun; Xie Leidong; Liu Rengzhong

    1992-01-01

    High performance liquid chromatography (HPLC) and ESR combined examination of radical species is an advanced techniques for separation and identification of complex radical species. At SRCL, Waters 990 HPLC has been used to separate the complex trapped radicals and Varian E-112 ESR spectrometer to record the spectra of single trapped radicals after HPLC separation. The advantages of the combined techniques are described as bellow: HPLC is used to separate the long-lived complex trapped radicals derived from reaction of short-lived radicals with spin trap. ESR spectra from single trapped radicals, obtained following HPLC separation of complex trapped radicals, are recorded one by one and well resolved. The structures of short-lived radicals can be inferred from the ESR spectra of the long-lived trapped radicals

  14. Preparation and controlled drug delivery applications of mesoporous silica polymer nanocomposites through the visible light induced surface-initiated ATRP

    Science.gov (United States)

    Huang, Long; Liu, Meiying; Mao, Liucheng; Xu, Dazhuang; Wan, Qing; Zeng, Guangjian; Shi, Yingge; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

    2017-08-01

    The mesoporous materials with large pore size, high specific surface area and high thermal stability have been widely utilized in a variety of fields ranging from environmental remediation to separation and biomedicine. However, surface modification of these silica nanomaterials is required to endow novel properties and achieve better performance for most of these applications. In this work, a new method has been established for surface modification of mesoporous silica nanoparticles (MSNs) that relied on the visible light induced atom transfer radical polymerization (ATRP). In the procedure, the copolymers composited with itaconic acid (IA) and poly(ethylene glycol)methyl acrylate (PEGMA) were grafted from MSNs using IA and PEGMA as the monomers and 10-Phenylphenothiazine(PTH) as the organic catalyst. The successful preparation of final polymer nanocomposites (named as MSNs-NH2-poly(IA-co-PEGMA)) were evidenced by a series of characterization techniques. More importantly, the anticancer agent cisplatin can be effectively loaded on MSNs-NH2-poly(IA-co-PEGMA) and controlled release it from the drug-loading composites with pH responsive behavior. As compared with conventional ATRP, the light induced surface-initiated ATRP could also be utilized for preparation of various silica polymer nanocomposites under rather benign conditions (e.g. absent of transition metal ions, low polymerization temperature and short polymerization time). Taken together, we have developed a rather promising strategy method for fabrication of multifunctional MSNs-NH2-poly(IA-co-PEGMA) with great potential for biomedical applications.

  15. Radical Evil

    Directory of Open Access Journals (Sweden)

    Carlos Manrique

    2007-12-01

    Full Text Available There is an aporia in Kant’s analysis of evil: he defines radical evilas an invisible disposition of the will, but he also demands an inferential connection between visible evil actions and this invisible disposition. This inference,however, undermines the radical invisibility of radical evil according to Kant’s own definition of the latter. Noting how this invisibility of moral worth is a distinctive feature of Kant’s approach to the moral problem, the paper then asks why, in the Groundwork, he nonetheless forecloses a question about evil that seems to be consistent with this approach. It is argued that to account for this aporia and this foreclosure, one has to interrogate the way in which the category of religion orients Kant’s incipient philosophy of history in Die Religion.

  16. The games radicals play : special issue on free radicals and radical ions

    OpenAIRE

    Walton, J.C.; Williams, F.

    2015-01-01

    Chemistry and Physics have aptly been described as “most excellent children of Intellect and Art” [1]. Both these “children” engage with many playthings, and molecules rank as one of their first favorites, especially radicals, which are amongst the most lively and exciting. Checking out radicals dancing to the music of entropy round their potential energy ballrooms is surely both entertaining and enlightening. Radicals’ old favorite convolutions are noteworthy, but the new styles, modes and a...

  17. Radical fashion and radical fashion innovation

    NARCIS (Netherlands)

    Zhang, D.; Benedetto, Di A.C.

    2010-01-01

    This is a study of the related concepts of radical fashion and radical fashion innovation. Radical fashions are defined here as those that may never enter the market at all, and exist primarily on runway shows, in exhibitions and in publicity; by contrast, radical fashion innovations may be very

  18. Surface-initiated growth of thin oxide coatings for Li-sulfur battery cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyu Tae; Black, Robert; Yim, Taeeun; Ji, Xiulei; Nazar, Linda F. [University of Waterloo, Department of Chemistry, Waterloo, ON (Canada)

    2012-12-15

    The concept of surface-initiated growth of oxides on functionalized carbons is introduced as a method to inhibit the dissolution of polysulfide ions in Li-S battery cathode materials. MO{sub x} (M: Si, V) thin layers are homogeneously coated on nanostructured carbon-sulfur composites. The coating significantly inhibits the dissolution of polysulfides on cycling, resulting in enhanced cycle performance and coulombic efficiency of the Li-S battery. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. An Appreciation of Free Radical Chemistry

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 9. An Appreciation of Free Radical Chemistry - 6. Experiments Involving Free Radicals. G Nagendrappa. Classroom Volume 10 Issue 9 September 2005 pp 79-84 ...

  20. WRF Simulation over the Eastern Africa by use of Land Surface Initialization

    Science.gov (United States)

    Sakwa, V. N.; Case, J.; Limaye, A. S.; Zavodsky, B.; Kabuchanga, E. S.; Mungai, J.

    2014-12-01

    The East Africa region experiences severe weather events associated with hazards of varying magnitude. It receives heavy precipitation which leads to wide spread flooding and lack of sufficient rainfall in some parts results into drought. Cases of flooding and drought are two key forecasting challenges for the Kenya Meteorological Service (KMS). The source of heat and moisture depends on the state of the land surface which interacts with the boundary layer of the atmosphere to produce excessive precipitation or lack of it that leads to severe drought. The development and evolution of precipitation systems are affected by heat and moisture fluxes from the land surface within weakly-sheared environments, such as in the tropics and sub-tropics. These heat and moisture fluxes during the day can be strongly influenced by land cover, vegetation, and soil moisture content. Therefore, it is important to represent the land surface state as accurately as possible in numerical weather prediction models. Improved modeling capabilities within the region have the potential to enhance forecast guidance in support of daily operations and high-impact weather over East Africa. KMS currently runs a configuration of the Weather Research and Forecasting (WRF) model in real time to support its daily forecasting operations, invoking the Non-hydrostatic Mesoscale Model (NMM) dynamical core. They make use of the National Oceanic and Atmospheric Administration / National Weather Service Science and Training Resource Center's Environmental Modeling System (EMS) to manage and produce the WRF-NMM model runs on a 7-km regional grid over Eastern Africa.SPoRT and SERVIR provide land surface initialization datasets and model verification tool. The NASA Land Information System (LIS) provide real-time, daily soil initialization data in place of interpolated Global Forecast System soil moisture and temperature data. Model verification is done using the Model Evaluation Tools (MET) package, in order

  1. In situ crosslinking of surface-initiated ring opening metathesis polymerization of polynorbornene for improved stability.

    Science.gov (United States)

    Fursule, Ishan A; Abtahi, Ashkan; Watkins, Charles B; Graham, Kenneth R; Berron, Brad J

    2018-01-15

    In situ crosslinking is expected to increase the solvent stability of coatings formed by surface-initiated ring opening metathesis polymerization (SI ROMP). Solvent-associated degradation limits the utility of SI ROMP coatings. SI ROMP coatings have a unique capacity for post-functionalization through reaction of the unsaturated site on the polymer backbone. Any post-reaction scheme which requires a liquid solvent has the potential to degrade the coating and lower the thickness of the resulting film. We designed a macromolecular crosslinking group based on PEG dinorbornene. The PEG length is tailored to the expected mean chain to chain distance during surface-initiated polymerization. This crosslinking macromer is randomly copolymerized with norbornene through SI ROMP on a gold coated substrate. The solvent stability of polynorbornene coatings with and without PEG dinorbornene is quantitatively determined, and the mechanism of degradation is further supported through XPS and AFM analyses. The addition of the 0.25mol% PEG dinorbornene significantly increases the solvent stability of the SI ROMP coatings. The crosslinker presence in the more stable films is supported with observable PEG absorbances by FTIR and an increase in contact angle hysteresis when compared to non-crosslinked coatings. The oxidation of the SI ROMP coatings is supported by the observation of carbonyl oxygen in the polynorbornene coatings. The rapid loss of the non-crosslinked SI ROMP coating corresponds to nanoscale pitting across the surface and micron-scale regions of widespread film loss. The crosslinked coatings have uniform nanoscale pitting, but the crosslinked films show no evidence of micron-scale film damage. In all, the incorporation of minimal crosslinking content is a simple strategy for improving the solvent stability of SI ROMP coatings. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Design of a New Near-Infrared Ratiometric Fluorescent Nanoprobe for Real-Time Imaging of Superoxide Anions and Hydroxyl Radicals in Live Cells and in Situ Tracing of the Inflammation Process in Vivo.

    Science.gov (United States)

    Liu, Rongjun; Zhang, Liangliang; Chen, Yunyun; Huang, Zirong; Huang, Yong; Zhao, Shulin

    2018-04-03

    The superoxide anion (O 2 •- ) and hydroxyl radical ( • OH) are important reactive oxygen species (ROS) used as biomarkers in physiological and pathological processes. ROS generation is closely related to the development of a variety of inflammatory diseases. However, the changes of ROS are difficult to ascertain with in situ tracing of the inflammation process by real-time monitoring, owing to the short half-lives of ROS and high tissue autofluorescence in vivo. Here we developed a new near-infrared (NIR) ratiometric fluorescence imaging approach by using a Förster resonance energy transfer (FRET)-based ratiometric fluorescent nanoprobe for real-time monitoring of O 2 •- and • OH generation and also by using in situ tracing of the inflammation process in vivo. The proposed nanoprobe was composed of PEG functionalized GQDs as the energy donor connecting to hydroIR783, serving as both the O 2 •- / • OH recognizing ligand and the energy acceptor. The nanoprobe not only exhibited a fast response to O 2 •- and • OH but also presented good biocomapatibility as well as a high photostability and signal-to-noise ratio. We have demonstrated that the proposed NIR ratiometric fluorescent nanoprobe can monitor the changes of O 2 •- and • OH in living RAW 264.7 cells via a drug mediating inflammation model and further realized visual monitoring of the change of O 2 •- and • OH in mice for in situ tracing of the inflammation process. Our design may provide a new paradigm for long-term and real-time imaging applications for in vivo tracing of the pathological process related to the inflammatory diseases.

  3. Preparing polymer brushes on polytetrafluoroethylene films by free radical polymerization

    International Nuclear Information System (INIS)

    Sun Wei; Chen Yiwang; Deng Qilan; Chen Lie; Zhou Lang

    2006-01-01

    Films of polytetrafluoroethylene (PTFE) were exposed to sodium naphthalenide (Na/naphtha) etchant so as to defluorinate the surface for obtaining hydroxyl functionality. Surface-initiators were immobilized on the PTFE films by esterification of 4,4'-azobis(4-cyanopentanoic acid) (ACP) and the hydroxyl groups covalently linked to the surface. Grafting of polymer brushes on the PTFE films was carried out by the surface-initiated free radical polymerization. Homopolymers brushes of methyl methacrylate (MMA) were prepared by free radical polymerization from the azo-functionalized PTFE surface. The chemical composition and topography of the graft-functionalized PTFE surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance (ATR) FT-IR spectroscopy and atomic force microscopy (AFM). Water contact angles on PTFE films were reduced by surface grafting of MMA

  4. Surface grafting of zwitterionic polymers onto dye doped AIE-active luminescent silica nanoparticles through surface-initiated ATRP for biological imaging applications

    Science.gov (United States)

    Mao, Liucheng; Liu, Xinhua; Liu, Meiying; Huang, Long; Xu, Dazhuang; Jiang, Ruming; Huang, Qiang; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

    2017-10-01

    Aggregation-induced emission (AIE) dyes have recently been intensively explored for biological imaging applications owing to their outstanding optical feature as compared with conventional organic dyes. The AIE-active luminescent silica nanoparticles (LSNPs) are expected to combine the advantages both of silica nanoparticles and AIE-active dyes. Although the AIE-active LSNPs have been prepared previously, surface modification of these AIE-active LSNPs with functional polymers has not been reported thus far. In this work, we reported a rather facile and general strategy for preparation of polymers functionalized AIE-active LSNPs through the surface-initiated atom transfer radical polymerization (ATRP). The AIE-active LSNPs were fabricated via direct encapsulation of AIE-active dye into silica nanoparticles through a non-covalent modified Stöber method. The ATRP initiator was subsequently immobilized onto these AIE-active LSNPs through amidation reaction between 3-aminopropyl-triethoxy-silane and 2-bromoisobutyryl bromide. Finally, the zwitterionic 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) was selected as model monomer and grafted onto MSNs through ATRP. The characterization results suggested that LSNPs can be successfully modified with poly(MPC) through surface-initiated ATRP. The biological evaluation results demonstrated that the final SNPs-AIE-pMPC composites possess low cytotoxicity, desirable optical properties and great potential for biological imaging. Taken together, we demonstrated that AIE-active LSNPs can be fabricated and surface modified with functional polymers to endow novel functions and better performance for biomedical applications. More importantly, this strategy developed in this work could also be extended for fabrication of many other LSNPs polymer composites owing to the good monomer adoptability of ATRP.

  5. Transitioning Enhanced Land Surface Initialization and Model Verification Capabilities to the Kenya Meteorological Department (KMD)

    Science.gov (United States)

    Case, Jonathan L.; Mungai, John; Sakwa, Vincent; Zavodsky, Bradley T.; Srikishen, Jayanthi; Limaye, Ashutosh; Blankenship, Clay B.

    2016-01-01

    Flooding, severe weather, and drought are key forecasting challenges for the Kenya Meteorological Department (KMD), based in Nairobi, Kenya. Atmospheric processes leading to convection, excessive precipitation and/or prolonged drought can be strongly influenced by land cover, vegetation, and soil moisture content, especially during anomalous conditions and dry/wet seasonal transitions. It is thus important to represent accurately land surface state variables (green vegetation fraction, soil moisture, and soil temperature) in Numerical Weather Prediction (NWP) models. The NASA SERVIR and the Short-term Prediction Research and Transition (SPoRT) programs in Huntsville, AL have established a working partnership with KMD to enhance its regional modeling capabilities. SPoRT and SERVIR are providing experimental land surface initialization datasets and model verification capabilities for capacity building at KMD. To support its forecasting operations, KMD is running experimental configurations of the Weather Research and Forecasting (WRF; Skamarock et al. 2008) model on a 12-km/4-km nested regional domain over eastern Africa, incorporating the land surface datasets provided by NASA SPoRT and SERVIR. SPoRT, SERVIR, and KMD participated in two training sessions in March 2014 and June 2015 to foster the collaboration and use of unique land surface datasets and model verification capabilities. Enhanced regional modeling capabilities have the potential to improve guidance in support of daily operations and high-impact weather and climate outlooks over Eastern Africa. For enhanced land-surface initialization, the NASA Land Information System (LIS) is run over Eastern Africa at 3-km resolution, providing real-time land surface initialization data in place of interpolated global model soil moisture and temperature data available at coarser resolutions. Additionally, real-time green vegetation fraction (GVF) composites from the Suomi-NPP VIIRS instrument is being incorporated

  6. Spectroscopic study of a DNA brush synthesized in situ by surface initiated enzymatic polymerization.

    Science.gov (United States)

    Khan, M Nuruzzaman; Tjong, Vinalia; Chilkoti, Ashutosh; Zharnikov, Michael

    2013-08-29

    We used a combination of synchrotron-based X-ray photoelectron spectroscopy (XPS) and angle-resolved near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to study the chemical integrity, purity, and possible internal alignment of single-strand (ss) adenine deoxynucleotide (poly(A)) DNA brushes. The brushes were synthesized by surface-initiated enzymatic polymerization (SIEP) on a 25-mer of adenine self-assembled monolayer (SAM) on gold (A25-SH), wherein the terminal 3'-OH of the A25-SH serve as the initiation sites for SIEP of poly(A). XPS and NEXAFS spectra of poly(A) brushes were found to be almost identical to those of A25-SH initiator, with no unambiguous traces of contamination. Apart from the well-defined chemical integrity and contamination-free character, the brushes were found to have a high degree of orientational order, with an upright orientation of individual strands, despite their large thickness up to ~55 nm, that corresponds to a chain length of at least several hundred nucleotides for individual ssDNA molecules. The orientational order exhibited by these poly(A) DNA brushes, mediated presumably by base stacking, was found to be independent of the brush thickness as long as the packing density was high enough. The well-defined character and orientational ordering of the ssDNA brushes make them a potentially promising system for different applications.

  7. On fatigue crack growth mechanisms of MMC: Reflection on analysis of 'multi surface initiations'

    International Nuclear Information System (INIS)

    Mkaddem, A.; El Mansori, M.

    2009-01-01

    This work attempts to examine the mechanisms of fatigue when cracks synergetically initiate in more than one site at the specimen surface. The metal matrix composites (MMC) i.e. silicon carbide particles reinforced aluminium matrix composites (Al/SiC p -MMC), seem to be good candidates to accelerate fatigue failures following multi surface initiations (MSI). Closure effects of MSI mechanisms on the variation of fatigue behaviour are explored for various stress states. Experiments were carried out using non pre-treated and pre-treated specimens. Using an Equivalent Ellipse Method (EEM), it is shown that the aspect of surface finish of specimen plays an important role on crack growth. Scanning Electron Microscope (SEM) inspections have lead to distinguishing the initiation regions from propagation regions and final separation regions. It is also revealed that the total lifetime of specimens is sensitive to heat treatment. Moreover, it is found that the appearance of MSI in cycled materials is more probable at high level of fatigue loads.

  8. Radical Change by Entrepreneurial Design

    National Research Council Canada - National Science Library

    Roberts, Nancy C

    1998-01-01

    .... How radical change in public policy has occurred in the past is then documented. We find examples of radical change by chance, radical change by consensus, radical change by learning, and radical change by entrepreneurial design...

  9. Biomimetic PEGylation of carbon nanotubes through surface-initiated RAFT polymerization.

    Science.gov (United States)

    Shi, Yingge; Zeng, Guanjian; Xu, Dazhuang; Liu, Meiying; Wang, Ke; Li, Zhen; Fu, Lihua; Zhang, Qingsong; Zhang, Xiaoyong; Wei, Yen

    2017-11-01

    Carbon nanotubes (CNTs) are a type of one-dimensional carbon nanomaterials that possess excellent physicochemical properties and have been potentially utilized for a variety of applications. Surface modification of CNTs with polymers is a general route to expand and improve the performance of CNTs and has attracted great research interest over the past few decades. Although many methods have been developed previously, most of these methods still showed some disadvantages, such as low efficiency, complex experimental procedure and harsh reaction conditions etc. In this work, we reported a practical and novel way to fabricate CNTs based polymer composites via the combination of mussel inspired chemistry and reversible addition fragmentation chain transfer (RAFT) polymerization. First, the amino group was introduced onto the surface of CNTs via self-polymerization of dopamine. Then, chain transfer agent can be immobilized on the amino groups functionalized CNTs to obtain CNT-PDA-CTA, which can be utilized for surface-initiated RAFT polymerization. A water soluble and biocompatible monomer poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) was adopted to fabricate pPEGMA functionalized CNTs through RAFT polymerization. The successful preparation of CNTs based polymer composites (CNT-pPEGMA) was confirmed by transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy in details. The CNT-pPEGMA showed good dispersibility and desirable biocompatibility, making them highly potential for biomedical applications. More importantly, a large number of CNTs based polymer composites could also be fabricated through the same strategy when different monomers were used due to the good monomer adaptability of RAFT polymerization. Therefore, this strategy should be a general method for preparation of various multifunctional CNTs based polymer composites. Copyright © 2017 Elsevier B.V. All rights

  10. A radical approach to radical innovation

    NARCIS (Netherlands)

    D. Deichmann (Dirk); J.C.M. van den Ende (Jan)

    2014-01-01

    textabstractInnovation pays. Amazon, Apple, Facebook, Google – nearly every one of today’s most successful companies has a talent for developing radical new ideas. But how best to encourage radical initiative taking from employees, and does their previous success or failure at it play a role?

  11. Nanostructured Polymer Brushes by UV-Assisted Imprint Lithography and Surface-Initiated Polymerization for Biological Functions

    NARCIS (Netherlands)

    Benetti, Edmondo Maria; Acikgoz, C.; Sui, Xiaofeng; Vratzov, Boris; Hempenius, Mark A.; Huskens, Jurriaan; Vancso, Gyula J.

    2011-01-01

    Functional polymer brush nanostructures are obtained by combining step-and-flash imprint lithography (SFIL) with controlled, surface-initiated polymerization (CSIP). Patterning is achieved at length scales such that the smallest elements have dimensions in the sub-100 nm range. The patterns exhibit

  12. Parameters Studies on Surface Initiated Rolling Contact Fatigue of Turnout Rails by Three-Level Unreplicated Saturated Factorial Design

    Directory of Open Access Journals (Sweden)

    Xiaochuan Ma

    2018-03-01

    Full Text Available Surface initiated rolling contact fatigue (RCF, mainly characterized by cracks and material stripping, is a common type of damage to turnout rails, which can not only shorten service life of turnout but also lead to poor running safety of vehicle. The rail surface initiated RCF of turnouts is caused by a long-term accumulation, the size and distribution of which are related to the dynamic parameters of the complicated vehicle-turnout system. In order to simulate the accumulation of rail damage, some random samples of dynamic parameters significantly influencing it should be input. Based on the three-level unreplicated saturated factorial design, according to the evaluation methods of H, P and B statistic values, six dynamic parameters that influence the rail surface initiated RCF in turnouts, namely running speed of vehicle, axle load, wheel-rail profiles, integral vertical track stiffness and wheel-rail friction coefficient, are obtained by selecting 13 dynamic parameters significantly influencing the dynamic vehicle-turnout interaction as the analysis factors, considering four dynamic response results, i.e., the normal wheel-rail contact force, longitudinal creep force, lateral creep force and wheel-rail contact patch area as the observed parameters. In addition, the rail surface initiated RCF behavior in turnouts under different wheel-rail creep conditions is analyzed, considering the relative motion of stock/switch rails. The results show that the rail surface initiated RCF is mainly caused by the tangential stress being high under small creep conditions, the normal and tangential stresses being high under large creep conditions, and the normal stress being high under pure spin creep conditions.

  13. Free radical inactivation of trypsin

    International Nuclear Information System (INIS)

    Cudina, Ivana; Jovanovic, S.V.

    1988-01-01

    Reactivities of free radical oxidants, radical OH, Br2-anion radical and Cl 3 COO radical and a reductant, CO2-anion radical, with trypsin and reactive protein components were determined by pulse radiolysis of aqueous solutions at pH 7, 20 0 C. Highly reactive free radicals, radical OH, Br2-anion radical and CO2-anion radical, react with trypsin at diffusion controlled rates. Moderately reactive trichloroperoxy radical, k(Cl 3 COO radical + trypsin) preferentially oxidizes histidine residues. The efficiency of inactivation of trypsin by free radicals is inversely proportional to their reactivity. The yields of inactivation of trypsin by radical OH, Br2-anion radical and CO2-anion radical are low, G(inactivation) = 0.6-0.8, which corresponds to ∼ 10% of the initially produced radicals. In contrast, Cl 3 COO radical inactivates trypsin with ∼ 50% efficiency, i.e. G(inactivation) = 3.2. (author)

  14. Hydrophobic modification of wood via surface-initiated ARGET ATRP of MMA

    Energy Technology Data Exchange (ETDEWEB)

    Fu Yanchun; Li Gang [Material Science and Engineering College, Northeast Forestry University, Harbin 150040 (China); Yu Haipeng, E-mail: yuhaipeng20000@yahoo.com.cn [Key laboratory of Bio-based Material Science and Technology of Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Material Science and Engineering College, Northeast Forestry University, Harbin 150040 (China); Liu Yixing, E-mail: yxl200488@sina.com [Key laboratory of Bio-based Material Science and Technology of Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Material Science and Engineering College, Northeast Forestry University, Harbin 150040 (China)

    2012-01-15

    To convert the hydrophilic surface of wood into a hydrophobic surface, the present study investigated activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) as a method of grafting methyl methacrylate (MMA) onto the wood surface. The wood treated with 2-bromoisobutyryl bromide and with the subsequently attached MMA via ARGET ATRP under different polymerization times (2 h, 4 h, 6 h, 8 h) were examined using scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. All the analyses confirmed that PMMA had been grafted onto the wood surface. Water contact angle measurement proved that the covering layer of PMMA on wood made the surface hydrophobic. Polymerization time had a positive influence on the contact angle value and higher contact angle can be produced with the prolongation of the polymerization time. When the reaction time was extended to 8 h, the contact angle of treated wood surface reached 130 Degree-Sign in the beginning, and remained at 116 Degree-Sign after 60 s. The ARGET ATRP method may raise an alteration on the wood surface modification.

  15. Red fluorescent chitosan nanoparticles grafted with poly(2-methacryloyloxyethyl phosphorylcholine) for live cell imaging.

    Science.gov (United States)

    Wang, Ke; Fan, Xingliang; Zhang, Xiaoyong; Zhang, Xiqi; Chen, Yi; Wei, Yen

    2016-08-01

    Poly(2-methacryloyloxyethyl phosphorylcholine) conjugated red fluorescent chitosan nanoparticles (GCC-pMPC) were facilely fabricated by "grafting from" method via surface initiated atom transfer radical polymerization (ATRP). Firstly, glutaraldehyde crosslinked red fluorescent chitosan nanoparticles (GCC NPs) with many amino groups and hydroxyl groups on their surface were prepared, which were then reacted with 2-bromoisobutyryl bromide to form GCC-Br; subsequently, poly(MPC) (pMPC) brushes were grafted onto GCC NPs surface using GCC-Br as initiator via ATRP. Compared with PEGylated nanoparticles, zwitterionic polymers modified nanoparticles demonstrated better performance in their cellular uptake. Moreover, the obtained GCC-pMPC demonstrated excellent water-dispersibility, biocompatibility, and photostability, which made them highly potential for long-term tracing applications. Importantly, the successful live cell imaging of GCC-pMPC would remarkably advance the research of their further bioapplications. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Fabrication of nonfouling, bactericidal, and bacteria corpse release multifunctional surface through surface-initiated RAFT polymerization.

    Science.gov (United States)

    Wang, Bailiang; Ye, Zi; Tang, Yihong; Han, Yuemei; Lin, Quankui; Liu, Huihua; Chen, Hao; Nan, Kaihui

    Infections after surgery or endophthalmitis are potentially blinding complications caused by bacterial adhesion and subsequent biofilm formation on the intraocular lens. Neither single-function anti-adhesion surface nor contacting killing surface can exhibit ideal antibacterial function. In this work, a novel (2-(dimethylamino)-ethyl methacrylate- co -2-methacryloyloxyethyl phosphorylcholine) (p (DMAEMA- co -MPC)) brush was synthesized by "grafting from" method through reversible-addition fragmentation chain transfer polymerization. 1-Bromoheptane was used to quaternize the p (DMAEMA- co -MPC) brush coating and to endow the surface with bactericidal function. The success of the surface functionalization was confirmed by atomic force microscopy, water contact angle, and spectroscopic ellipsometry. The quaternary ammonium salt units were employed as efficient disinfection that can eliminate bacteria through contact killing, whereas the 2-methacryloyloxyethyl phosphorylcholine units were introduced to suppress unwanted nonspecific adsorption. The functionalized poly(dimethyl siloxane) surfaces showed efficiency in reducing bovine serum albumin adsorption and in inhibiting bacteria adhesion and biofilm formation. The copolymer brushes also demonstrated excellent bactericidal function against gram-positive ( Staphylococcus aureus ) bacteria measured by bacteria live/dead staining and shake-flask culture methods. The surface biocompatibility was evaluated by morphology and activity measurement with human lens epithelial cells in vitro. The achievement of the p (DMAEMA + - co -MPC) copolymer brush coating with nonfouling, bactericidal, and bacteria corpse release properties can be used to modify intraocular lenses.

  17. Fabrication of nonfouling, bactericidal, and bacteria corpse release multifunctional surface through surface-initiated RAFT polymerization

    Directory of Open Access Journals (Sweden)

    Wang B

    2016-12-01

    Full Text Available Bailiang Wang,1,2 Zi Ye,1 Yihong Tang,1 Yuemei Han,1 Quankui Lin,1,2 Huihua Liu,2 Hao Chen,1,2 Kaihui Nan1,2 1School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 2Wenzhou Institute of Biomaterials and Engineering, Chinese Academy of Sciences, Wenzhou, People’s Republic of China Abstract: Infections after surgery or endophthalmitis are potentially blinding complications caused by bacterial adhesion and subsequent biofilm formation on the intraocular lens. Neither single-function anti-adhesion surface nor contacting killing surface can exhibit ideal antibacterial function. In this work, a novel (2-(dimethylamino-ethyl methacrylate-co-2-methacryloyloxyethyl phosphorylcholine (p (DMAEMA-co-MPC brush was synthesized by “grafting from” method through reversible–addition fragmentation chain transfer polymerization. 1-Bromoheptane was used to quaternize the p (DMAEMA-co-MPC brush coating and to endow the surface with bactericidal function. The success of the surface functionalization was confirmed by atomic force microscopy, water contact angle, and spectroscopic ellipsometry. The quaternary ammonium salt units were employed as efficient disinfection that can eliminate bacteria through contact killing, whereas the 2-methacryloyloxyethyl phosphorylcholine units were introduced to suppress unwanted nonspecific adsorption. The functionalized poly(dimethyl siloxane surfaces showed efficiency in reducing bovine serum albumin adsorption and in inhibiting bacteria adhesion and biofilm formation. The copolymer brushes also demonstrated excellent bactericidal function against gram-positive (Staphylococcus aureus bacteria measured by bacteria live/dead staining and shake-flask culture methods. The surface biocompatibility was evaluated by morphology and activity measurement with human lens epithelial cells in vitro. The achievement of the p (DMAEMA+-co-MPC copolymer brush coating with nonfouling, bactericidal, and

  18. Fabrication of luminescent hydroxyapatite nanorods through surface-initiated RAFT polymerization: Characterization, biological imaging and drug delivery applications

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Chunning [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi’an, 710069 (China); Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Zheng, Xiaoyan [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi’an, 710069 (China); Liu, Meiying; Xu, Dazhuang; Huang, Hongye; Deng, Fengjie [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Hui, Junfeng, E-mail: huijunfeng@126.com [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi’an, 710069 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China)

    2016-11-15

    Highlights: • Hydrophobic hydroxyapatite nanorods were obtained from hydrothermal synthesis. • Surface initiated RAFT polymerization was adopted to surface modification of hydroxyapatite nanorods. • These modified hydroxyapatite nanorods showed high water dispersibility and biocompatibility. • These modified hydroxyapatite nanorods can be used for controlled drug delivery. - Abstract: Hydroxyapatite nanomaterials as an important class of nanomaterials, have been widely applied for different biomedical applications for their excellent biocompatibility, biodegradation potential and low cost. In this work, hydroxyapatite nanorods with uniform size and morphology were prepared through hydrothermal synthesis. The surfaces of these hydroxyapatite nanorods are covered with hydrophobic oleic acid, making them poor dispersibility in aqueous solution and difficult for biomedical applications. To overcome this issue, a simple surface initiated polymerization strategy has been developed via combination of the surface ligand exchange and reversible addition fragmentation chain transfer (RAFT) polymerization. Hydroxyapatite nanorods were first modified with Riboflavin-5-phosphate sodium (RPSSD) via ligand exchange reaction between the phosphate group of RPSSD and oleic acid. Then hydroxyl group of nHAp-RPSSD was used to immobilize chain transfer agent, which was used as the initiator for surface-initiated RAFT polymerization. The nHAp-RPSSD-poly(IA-PEGMA) nanocomposites were characterized by means of {sup 1}H nuclear magnetic resonance, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermal gravimetric analysis in detailed. The biocompatibility, biological imaging and drug delivery of nHAp-RPSSD-poly(IA-PEGMA) were also investigated. Results showed that nHAp-RPSSD-poly(IA-PEGMA) exhibited excellent water dispersibility, desirable optical properties, good biocompatibility and high drug loading capability, making them promising candidates for

  19. Fabrication of luminescent hydroxyapatite nanorods through surface-initiated RAFT polymerization: Characterization, biological imaging and drug delivery applications

    International Nuclear Information System (INIS)

    Heng, Chunning; Zheng, Xiaoyan; Liu, Meiying; Xu, Dazhuang; Huang, Hongye; Deng, Fengjie; Hui, Junfeng; Zhang, Xiaoyong; Wei, Yen

    2016-01-01

    Highlights: • Hydrophobic hydroxyapatite nanorods were obtained from hydrothermal synthesis. • Surface initiated RAFT polymerization was adopted to surface modification of hydroxyapatite nanorods. • These modified hydroxyapatite nanorods showed high water dispersibility and biocompatibility. • These modified hydroxyapatite nanorods can be used for controlled drug delivery. - Abstract: Hydroxyapatite nanomaterials as an important class of nanomaterials, have been widely applied for different biomedical applications for their excellent biocompatibility, biodegradation potential and low cost. In this work, hydroxyapatite nanorods with uniform size and morphology were prepared through hydrothermal synthesis. The surfaces of these hydroxyapatite nanorods are covered with hydrophobic oleic acid, making them poor dispersibility in aqueous solution and difficult for biomedical applications. To overcome this issue, a simple surface initiated polymerization strategy has been developed via combination of the surface ligand exchange and reversible addition fragmentation chain transfer (RAFT) polymerization. Hydroxyapatite nanorods were first modified with Riboflavin-5-phosphate sodium (RPSSD) via ligand exchange reaction between the phosphate group of RPSSD and oleic acid. Then hydroxyl group of nHAp-RPSSD was used to immobilize chain transfer agent, which was used as the initiator for surface-initiated RAFT polymerization. The nHAp-RPSSD-poly(IA-PEGMA) nanocomposites were characterized by means of "1H nuclear magnetic resonance, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermal gravimetric analysis in detailed. The biocompatibility, biological imaging and drug delivery of nHAp-RPSSD-poly(IA-PEGMA) were also investigated. Results showed that nHAp-RPSSD-poly(IA-PEGMA) exhibited excellent water dispersibility, desirable optical properties, good biocompatibility and high drug loading capability, making them promising candidates for biological

  20. Orgasm after radical prostatectomy

    NARCIS (Netherlands)

    Koeman, M; VanDriel, MF; Schultz, WCMW; Mensink, HJA

    Objective To evaluate the ability to obtain and the quality of orgasm after radical prostatectomy, Patients and methods The orgasms experienced after undergoing radical prostatectomy were evaluated in 20 men (median age 65 years, range 56-76) using a semi-structured interview and a self-administered

  1. Physiology of free radicals

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2011-01-01

    Full Text Available Free radicals imply that every atom, molecule, ion, group of atoms, or molecules with one or several non-paired electrons in outer orbital. Among these are: nitrogenoxide (NO•, superoxide-anion-radical (O2•-, hydroxyl radical (OH•, peroxyl radical (ROO•, alcoxyl radical (RO• and hydroperoxyl radical (HO2•. However, reactive oxygen species also include components without non-paired electrons in outer orbital (so-called reactive non-radical agents, such as: singlet oxygen (1O2, peroxynitrite (ONOO-, hydrogen-peroxide (H2O2, hypochloric acid (eg. HOCl and ozone (O3. High concentrations of free radicals lead to the development of oxidative stress which is a precondition for numerous pathological effects. However, low and moderate concentrations of these matter, which occur quite normally during cell metabolic activity, play multiple significant roles in many reactions. Some of these are: regulation of signal pathways within the cell and between cells, the role of chemoattractors and leukocyte activators, the role in phagocytosis, participation in maintaining, changes in the position and shape of the cell, assisting the cell during adaption and recovery from damage (e.g.caused by physical effort, the role in normal cell growth, programmed cell death (apoptosis and cell ageing, in the synthesis of essential biological compounds and energy production, as well as the contribution to the regulation of the vascular tone, actually, tissue vascularization.

  2. Radicals in arithmetic

    NARCIS (Netherlands)

    W.J. Palenstijn (Willem Jan)

    2014-01-01

    htmlabstractLet K be a field. A radical is an element of the algebraic closure of K of which a power is contained in K. In this thesis we develop a method for determining what we call entanglement. This describes unexpected additive relations between radicals, and is encoded in an entanglement

  3. Radicals in arithmetic

    NARCIS (Netherlands)

    Palenstijn, Willem Jan

    2014-01-01

    Let K be a field. A radical is an element of the algebraic closure of K of which a power is contained in K. In this thesis we develop a method for determining what we call entanglement. This describes unexpected additive relations between radicals, and is encoded in an entanglement group. We give

  4. Muonium and muonic radicals

    International Nuclear Information System (INIS)

    Burkhard, P.; Fischer, H.; Roduner, E.; Strub, W.; Geeson, D.; Symons, M.C.R.

    1985-01-01

    An energetic positive muon which is injected in a liquid sample of substrate molecules (S) creates an ionization track consisting of substrate cations (S + ) and electrons. Near the end of this track the muon may combine with an electron to form muonium (Mu) which is observable in inert liquids, but which reacts by addition to form a radical. Alternatively, the electron can add to S to form S - , which then combines with the muon to form the radical. Furthermore, instead of ending up in Mu or in a radical the muon may stay in a diamagnetic environment as a solvated muon, or as a muon substituting a proton in a molecule. Of interest in these schemes are the mechanisms and rates of formation of muonated radicals and in particular the rate constants for their reactions to products. Investigations are based on the observation of Mu and the radical by means of the μSR technique in transverse magnetic fields. (Auth.)

  5. Living the Utopia

    DEFF Research Database (Denmark)

    Davis, John; Warring, Anette Elisabeth

    2011-01-01

    This article examines experiments in communal living in Britain and Denmark in the early 1970s, using life-story interviews from seventeen members of two British and two Danish communes. It examines communal living as a fusion of radical political principles with the practice of experimental...... collective living. It concludes that the movement's egalitarian principles of resource-sharing, gender equality and the avoidance of hierarchies were broadly achieved, even if the movement obviously did not realize its more ambitious objective of undermining the bourgeois family. Though none...... of the interviewees lives communally now, most remain faithful to the principles behind the movement....

  6. Salvage robotic radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Samuel D Kaffenberger

    2014-01-01

    Full Text Available Failure of non-surgical primary treatment for localized prostate cancer is a common occurrence, with rates of disease recurrence ranging from 20% to 60%. In a large proportion of patients, disease recurrence is clinically localized and therefore potentially curable. Unfortunately, due to the complex and potentially morbid nature of salvage treatment, radical salvage surgery is uncommonly performed. In an attempt to decrease the morbidity of salvage therapy without sacrificing oncologic efficacy, a number of experienced centers have utilized robotic assistance to perform minimally invasive salvage radical prostatectomy. Herein, we critically evaluate the existing literature on salvage robotic radical prostatectomy with a focus on patient selection, perioperative complications and functional and early oncologic outcomes. These results are compared with contemporary and historical open salvage radical prostatectomy series and supplemented with insights we have gained from our experience with salvage robotic radical prostatectomy. The body of evidence by which conclusions regarding the efficacy and safety of robotic salvage radical prostatectomy can be drawn comprises fewer than 200 patients with limited follow-up. Preliminary results are promising and some outcomes have been favorable when compared with contemporary open salvage prostatectomy series. Advantages of the robotic platform in the performance of salvage radical prostatectomy include decreased blood loss, short length of stay and improved visualization. Greater experience is required to confirm the long-term oncologic efficacy and functional outcomes as well as the generalizability of results achieved at experienced centers.

  7. Evidence of radicals created by plasma in bacteria in water

    International Nuclear Information System (INIS)

    Lee, Chae Bok; Na, Young Ho; Hong, Tae-Eun; Choi, Eun Ha; Uhm, Han S.; Baik, Ku Youn; Kwon, Gichung

    2014-01-01

    Heavy water (D 2 O) was introduced into a non-thermal plasma-jet (NTPJ) device to generate deuterium monoxide (OD) radicals at room temperature. Owing to the similar reactivity and low prevalence of deuterium in nature, OD radicals can be utilized to visualize the OH radical interactions with water and living cells. Escherichia coli in water were treated with OD radicals, and D atom incorporation into cells was visualized using time-of-flight SIMS and Nano-SIMS. The results show that D atoms from NTPJ reach the cytoplasm of E. coli in H 2 O, indicating the usefulness of this OD-tracking method for the study of radical interactions with living cells.

  8. Reactions of inorganic free radicals with liver protecting drugs

    International Nuclear Information System (INIS)

    Gyoergy, I.; Foeldiak, G.; Blazovics, A.; Feher, J.

    1990-01-01

    Liver protecting drugs, silibinin, a flavonolignane, and the dihydroquinoline derivatives, CH 402 and MTDQ-DA, were shown to inhibit processes in which enzymatically or non-enzymatically generated free radicals were involved. Inorganic free radicals (N 3 , (SCN) 2 - , OH, Trp, CO 2 - , O 2 - ) produced by pulse radiolysis readily react with the compounds, which transform into exceptionally long-lived, unreactive transients. Time evolution of the UV and visible spectra indicate that oxidising radicals form a phenoxyl type radical from silibinin, while OH forms an adduct by attacking, simultaneously, at various sites of the molecule. Superoxide radicals reduce silibinin and oxidise CH 402 and MTDQ-DA. It is concluded that the drugs might exhibit antioxidant behavior in living systems. (author)

  9. Gnosticism and Radical Feminism

    DEFF Research Database (Denmark)

    Cahana, Jonathan

    2016-01-01

    and radical feminism would easily fall under this definition. There is, however, one major difference: since radical feminism is a relatively recent phenomenon which also benefited from modern modes of text production and preservation, almost all of the sources are still with us. This, in turn, may allow us...... to use radical feminism to make certain aspects of ancient Gnosticism re-emerge from their long submersion, provided that enough similarities can be independently drawn between the two phenomena to merit such a comparison. This paper therefore presents a comparison between concepts and positions...

  10. Homegrown religious radicalization

    DEFF Research Database (Denmark)

    Khawaja, Iram

    It has been reported that a growing number of youngsters from Western Europe are engaging in conflicts motivated by religious and political conflicts in the Middle East. This paper explores the reasons behind this seemingly religious radicalization from the point of view of the youngsters...... youngsters and parents of youngsters who have chosen a radicalized path in life. The paper will shed light on how the sense of and yearning for belonging and recognition have to be taken into account in our understanding of homegrown religious radicalization...

  11. Radical chemistry of artemisinin

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Evgenii T; Solodova, S L; Denisova, Taisa G [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2011-12-29

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  12. Radical chemistry of artemisinin

    Science.gov (United States)

    Denisov, Evgenii T.; Solodova, S. L.; Denisova, Taisa G.

    2010-12-01

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  13. Radical chemistry of artemisinin

    International Nuclear Information System (INIS)

    Denisov, Evgenii T; Solodova, S L; Denisova, Taisa G

    2010-01-01

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  14. Radical's view of sciences

    International Nuclear Information System (INIS)

    Mittal, J.P.

    2004-01-01

    Full text: General concept in radiation biology is that free radicals are highly reactive and they can damage vital cellular molecules leading to injurious effects. However, in this talk, evidence will be presented through the techniques of electron paramagnetic resonance ( EPR ) and pulse radiolysis that free radicals can be highly selective in their reaction with the target molecules. In addition, attempts will be made to present a brief account of emerging scenario of free radical generation, identification and their involvement in radiation damage mechanisms in chemical and biological systems

  15. Radical chemistry of artemisinin

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Evgenii T; Solodova, S L; Denisova, Taisa G [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2010-12-29

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  16. Abstracts of 2. symposium on free radicals in biology and medicine

    International Nuclear Information System (INIS)

    1994-01-01

    The abstracts presented in the booklet concern influence of free radicals (frequently generated by ionizing radiation) on DNA, proteins, lipids and chromatin of various living organisms. Works show, that free radicals cause serious damages in biological systems leading to carcinogenesis and many genetic diseases. Thus understanding of mechanisms of free radical action is important issue in medicine and life sciences

  17. Abstracts of 2. symposium on free radicals in biology and medicine

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    The abstracts presented in the booklet concern influence of free radicals (frequently generated by ionizing radiation) on DNA, proteins, lipids and chromatin of various living organisms. Works show, that free radicals cause serious damages in biological systems leading to carcinogenesis and many genetic diseases. Thus understanding of mechanisms of free radical action is important issue in medicine and life sciences.

  18. Moderate and Radical Islam

    National Research Council Canada - National Science Library

    Rabasa, Angel

    2005-01-01

    This report presents the statement of Angel Rabasa, PhD, Senior Policy Analyst, The RAND Corporation, to the Committee on Armed Services, Defense Review Terrorism and Radical Islam Gap Panel, United...

  19. Functionalization of vertically aligned carbon nanotubes with polystyrene via surface initiated reversible addition fragmentation chain transfer polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Macdonald, Thomas; Gibson, Christopher T.; Constantopoulos, Kristina; Shapter, Joseph G. [Flinders Centre for Nanoscale Science and Technology, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA, 5001 (Australia); Ellis, Amanda V., E-mail: amanda.ellis@flinders.edu.au [Flinders Centre for Nanoscale Science and Technology, School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA, 5001 (Australia)

    2012-01-15

    Here we demonstrate the covalent attachment of vertically aligned (VA) acid treated single-walled carbon nanotubes (SWCNTs) onto a silicon substrate via dicyclohexylcarbodiimide (DCC) coupling chemistry. Subsequently, the pendant carboxyl moieties on the sidewalls of the VA-SWCNTs were derivatized to acyl chlorides, and then finally to bis(dithioester) moieties using a magnesium chloride dithiobenzoate salt. The bis(dithioester) moieties were then successfully shown to act as a chain transfer agent (CTA) in the reversible addition fragmentation chain transfer (RAFT) polymerization of styrene in a surface initiated 'grafting-from' process from the VA-SWCNT surface. Atomic force microscopy (AFM) verified vertical alignment of the SWCNTs and the maintenance thereof throughout the synthesis process. Finally, Raman scattering spectroscopy and AFM confirmed polystyrene functionalization.

  20. Functionalization of vertically aligned carbon nanotubes with polystyrene via surface initiated reversible addition fragmentation chain transfer polymerization

    International Nuclear Information System (INIS)

    Macdonald, Thomas; Gibson, Christopher T.; Constantopoulos, Kristina; Shapter, Joseph G.; Ellis, Amanda V.

    2012-01-01

    Here we demonstrate the covalent attachment of vertically aligned (VA) acid treated single-walled carbon nanotubes (SWCNTs) onto a silicon substrate via dicyclohexylcarbodiimide (DCC) coupling chemistry. Subsequently, the pendant carboxyl moieties on the sidewalls of the VA-SWCNTs were derivatized to acyl chlorides, and then finally to bis(dithioester) moieties using a magnesium chloride dithiobenzoate salt. The bis(dithioester) moieties were then successfully shown to act as a chain transfer agent (CTA) in the reversible addition fragmentation chain transfer (RAFT) polymerization of styrene in a surface initiated “grafting-from” process from the VA-SWCNT surface. Atomic force microscopy (AFM) verified vertical alignment of the SWCNTs and the maintenance thereof throughout the synthesis process. Finally, Raman scattering spectroscopy and AFM confirmed polystyrene functionalization.

  1. Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

    International Nuclear Information System (INIS)

    Guo Zhanhu; Park, Sung; Wei Suying; Pereira, Tony; Moldovan, Monica; Karki, Amar B; Young, David P; Hahn, H Thomas

    2007-01-01

    Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer-particle interactions

  2. Introduction: Teaching Black Lives Matter

    OpenAIRE

    Paula Austin; Erica Cardwell; Christopher Kennedy; Robyn Spencer

    2016-01-01

    An introduction to Radical Teacher, Issue 106: Teaching Black Lives Matter. This issue brings together a diverse collection of articles exploring educator’s responses, strategies, and stories on how #BlackLivesMatter has informed their teaching practice, the content of their courses, and their personal relationship to colleagues, family, friends, and self.

  3. Introduction: Teaching Black Lives Matter

    Directory of Open Access Journals (Sweden)

    Paula Austin

    2016-11-01

    Full Text Available An introduction to Radical Teacher, Issue 106: Teaching Black Lives Matter. This issue brings together a diverse collection of articles exploring educator’s responses, strategies, and stories on how #BlackLivesMatter has informed their teaching practice, the content of their courses, and their personal relationship to colleagues, family, friends, and self.

  4. Free radicals created by radiation and aging symptoms

    International Nuclear Information System (INIS)

    Ashry, O.M.

    2012-01-01

    The universality of aging implies that its cause is basically the same in all species. A free radical hypothesis of aging has been proposed that the free radicals produced during normal metabolism of the cell over time damage DNA and other macromolecules leading to degenerative diseases, malignancies, and eventual death of vital cells which in turn causes aging and death of the organism. This hypothesis is supported by several observations. Radiation produces its biologic effect through free radical formation and causes premature aging. Second, the age pigment lipo fuscin is associated with lipid peroxidation. The hypothesis that oxygen radicals play a role in aging is also supported by the observation that, in general, long-lived species produce less endogenous free oxygen radicals because of their lower metabolic rate. Long-lived animals also have more superoxide dismutase than do their short-lived counterparts, and animal species with the longest lifespan have the highest levels of superoxide dismutase. Oxidative DNA damage is rapidly and effectively repaired. It has been estimated that there are several thousand oxidative DNA damage sites in a human cell every day, and the majority of these are repaired. However, a small fraction of unrepaired lesions could cause permanent changes in DNA and might be a major contributor to aging and cancer. A consequence of the free radical hypothesis of aging is the idea that free radical scavenging agents might be used to prevent aging. (author)

  5. Laparoscopic radical trachelectomy.

    Science.gov (United States)

    Rendón, Gabriel J; Ramirez, Pedro T; Frumovitz, Michael; Schmeler, Kathleen M; Pareja, Rene

    2012-01-01

    The standard treatment for patients with early-stage cervical cancer has been radical hysterectomy. However, for women interested in future fertility, radical trachelectomy is now considered a safe and feasible option. The use of minimally invasive surgical techniques to perform this procedure has recently been reported. We report the first case of a laparoscopic radical trachelectomy performed in a developing country. The patient is a nulligravid, 30-y-old female with stage IB1 adenocarcinoma of the cervix who desired future fertility. She underwent a laparoscopic radical trachelectomy and bilateral pelvic lymph node dissection. The operative time was 340 min, and the estimated blood loss was 100mL. There were no intraoperative or postoperative complications. The final pathology showed no evidence of residual disease, and all pelvic lymph nodes were negative. At 20 mo of follow-up, the patient is having regular menses but has not yet attempted to become pregnant. There is no evidence of recurrence. Laparoscopic radical trachelectomy with pelvic lymphadenectomy in a young woman who desires future fertility may also be an alternative technique in the treatment of early cervical cancer in developing countries.

  6. The Games Radicals Play: Special Issue on Free Radicals and Radical Ions

    Directory of Open Access Journals (Sweden)

    John C. Walton

    2015-02-01

    Full Text Available Chemistry and Physics have aptly been described as “most excellent children of Intellect and Art” [1]. Both these “children” engage with many playthings, and molecules rank as one of their first favorites, especially radicals, which are amongst the most lively and exciting. Checking out radicals dancing to the music of entropy round their potential energy ballrooms is surely both entertaining and enlightening. Radicals’ old favorite convolutions are noteworthy, but the new styles, modes and arrangements appearing on the scene are even more interesting. Some of these are ephemeral and enjoy only a brief appearance, others are retro-types reappearing in new guises, still others are genuinely new and “go viral” in the scientific world. This Special Issue of Molecules contains the observations and reflections of a select group of chemists and physicists fascinated by this spectacle. It contains an eclectic mix reflecting on new modes and advances as well as on permutations and combinations that revive mature themes. [...

  7. Radical dematerialization and degrowth

    Science.gov (United States)

    Kallis, Giorgos

    2017-05-01

    The emission targets agreed in Paris require a radical reduction of material extraction, use and disposal. The core claim of this article is that a radical dematerialization can only be part and parcel of degrowth. Given that capitalist economies are designed to grow, this raises the question of whether, and under what circumstances, the inevitable `degrowth' can become socially sustainable. Three economic policies are discussed in this direction: work-sharing, green taxes and public money. This article is part of the themed issue 'Material demand reduction'.

  8. Muon substituted free radicals

    International Nuclear Information System (INIS)

    Burkhard, P.; Fischer, H.; Roduner, E.; Strub, W.; Gygax, F.N.; Brinkman, G.A.; Louwrier, P.W.F.; McKenna, D.; Ramos, M.; Webster, B.C.

    1984-01-01

    Spin polarized energetic positive muons are injected as magnetic probes into unsaturated organic liquids. They are implemented via fast chemical processes ( -10 s) in various molecules. Of particular interest among these are muonium substituted free radicals. The technique allows determination of accurate rate coefficients for fast chemical reactions of radicals. Furthermore, radiochemical processes occuring in picoseconds after injection of the muon are studied. Of fundamental interest are also the structural and dynamical implications of substituting a proton by a muon, or in other terms, a hydrogen atom by a muonium atom. Selected examples for each of these three types of experiments are given. (Auth.)

  9. Oxidation of aromatic amines and diamines by OH radicals. Formation and ionization constants of amine cation radicals in water

    International Nuclear Information System (INIS)

    Hayon, E.; Rao, P.S.

    1975-01-01

    The one-electron oxidation by hydroxyl radicals of aromatic amines and diamines in water was studied using the fast-reaction technique of pulse radiolysis and kinetic absorption spectrophotometry. The following compounds were examined: N,N,N 1 ,N 1 - tetramethyl-p-phenylenediamine (TMPD), p-phenylenediamine (PD), N,N-dimethyl-p-phenylenediamene (DMPD), N,N,N 1 ,N 1 -tetramethylbenzidine (TMB), and diphenylamine (DPA). The main initial reaction of the OH radicals is suggested to be an addition to these compounds to give absorption spectra which absorb strongly in the visible and uv regions. These OH radical adducts decay by first-order kinetics and have lifetimes of approximately 5-50 μsec, dependent on the pH, buffer concentration, and the nature of the aromatic amines and diamines. They decay to give species with somewhat similar absorption spectra and extinction coefficients, which are very long lived in the absence of oxygen. The latter species are assigned to the cation radicals TMPD. + , PD. + , DMPD. + , TMB. + , and DPA. + . The OH radical adducts and the cation radicals have acid-base properties. The pK/sub a/ values of the cation radicals TMPDH. 2+ , PDH. 2+ , DMPDH. 2+ , TMBH. 2+ , and DPAH. 2+ were found to be 5.3, 5.9, 6.1, 5.1, and 4.2, respectively. The results indicate that these aromatic amines and diamines can be oxidized by free radicals to yield the corresponding cation radicals. (U.S.)

  10. Optimisation of Surface-Initiated Photoiniferter-Mediated Polymerisation under Confinement, and the Formation of Block Copolymers in Mesoporous Films

    Directory of Open Access Journals (Sweden)

    Jessica C. Tom

    2017-10-01

    Full Text Available Nature as the ultimate inspiration can direct, gate, and selectively transport species across channels to fulfil a specific targeted function. Harnessing such precision over local structure and functionality at the nanoscale is expected to lead to indispensable developments in synthetic channels for application in catalysis, filtration and sensing, and in drug delivery. By combining mesoporous materials with localised charge-switchable poly(2-(dimethylaminoethyl methacrylate (PDMAEMA brushes, precisely controlling pore filling and exploring the possibility of incorporating two different responsive polymers, we hope to approach the precision control of natural systems in the absence of an external force. Here, we report a simple one-step approach to prepare a mesoporous silica thin film with ~8 nm pores functionalised with a photoiniferter by combining sol–gel chemistry and evaporation-induced self-assembly (EISA. We show that surface-initiated photoiniferter-mediated polymerisation (SI-PIMP allows the incorporation of a high polymer content up to geometrical pore blocking by the simple application of UV light in the presence of a monomer and solvent, proceeding in a controlled manner in pore sizes below 10 nm, with the potential to tune the material properties through the formation of surface-grafted block copolymers.

  11. Counter radicalization development assistance

    OpenAIRE

    van Hippel, Karin

    2006-01-01

    The paper reviews current research and practice and recommends strategies for development agencies working in the Arab and Muslim world. It builds on the basic assumption that the realization of the Millennium Development Goals will be vital to reduce support for terrorism in the long term. Within this overall framework, emphasis is placed on particular programs that could be specifically applied to counter radicalization.

  12. Radically enhanced molecular recognition

    KAUST Repository

    Trabolsi, Ali; Khashab, Niveen M.; Fahrenbach, Albert C.; Friedman, Douglas C.; Colvin, Michael T.; Coti, Karla K.; Bení tez, Diego S.; Tkatchouk, Ekaterina; Olsen, John Carl; Belowich, Matthew E.; Carmieli, Raanan; Khatib, Hussam A.; Goddard, William Andrew III; Wasielewski, Michael R.; Stoddart, Fraser Fraser Raser

    2009-01-01

    The tendency for viologen radical cations to dimerize has been harnessed to establish a recognition motif based on their ability to form extremely strong inclusion complexes with cyclobis(paraquat-p-phenylene) in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chemistry, extending its practice beyond the traditional reliance on neutral and charged guests and hosts. In particular, transporting the concept of radical dimerization into the field of mechanically interlocked molecules introduces a higher level of control within molecular switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochemical potentials. In a tristable [2]rotaxane composed of a cyclobis(paraquat-p-phenylene) ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidation, it moves from the tetrathiafulvalene to the dioxynaphthalene, and on reduction, to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication. © 2010 Macmillan Publishers Limited. All rights reserved.

  13. Sexuality Following Radical Prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Serefoglu, Ege C; Albersen, Maarten

    2017-01-01

    incontinence in relation to sexual activity after surgery. This can present at the time of orgasm (ie, climacturia) or arise during arousal. In general, the problem subsides with time and pelvic floor training and tension penile loops can be used as treatments. Orgasmic disturbances after radical prostatectomy...

  14. Radically enhanced molecular recognition

    KAUST Repository

    Trabolsi, Ali

    2009-12-17

    The tendency for viologen radical cations to dimerize has been harnessed to establish a recognition motif based on their ability to form extremely strong inclusion complexes with cyclobis(paraquat-p-phenylene) in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chemistry, extending its practice beyond the traditional reliance on neutral and charged guests and hosts. In particular, transporting the concept of radical dimerization into the field of mechanically interlocked molecules introduces a higher level of control within molecular switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochemical potentials. In a tristable [2]rotaxane composed of a cyclobis(paraquat-p-phenylene) ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidation, it moves from the tetrathiafulvalene to the dioxynaphthalene, and on reduction, to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication. © 2010 Macmillan Publishers Limited. All rights reserved.

  15. Online Radicalization: Bangladesh Perspective

    Science.gov (United States)

    2017-06-09

    radicalization through cyberspace, Bangladesh mostly implements hard powers such as removing contents and restricting access to the internet. However, freedom...cyberspace, Bangladesh mostly implements hard powers such as removing contents and restricting access to the internet. However, freedom of speech...67 An Organizational Approach to Implement the Measures........................................ 69 Formation of

  16. Cation radicals of xanthophylls.

    Science.gov (United States)

    Galinato, Mary Grace I; Niedzwiedzki, Dariusz; Deal, Cailin; Birge, Robert R; Frank, Harry A

    2007-10-01

    Carotenes and xanthophylls are well known to act as electron donors in redox processes. This ability is thought to be associated with the inhibition of oxidative reactions in reaction centers and light-harvesting pigment-protein complexes of photosystem II (PSII). In this work, cation radicals of neoxanthin, violaxanthin, lutein, zeaxanthin, beta-cryptoxanthin, beta-carotene, and lycopene were generated in solution using ferric chloride as an oxidant and then studied by absorption spectroscopy. The investigation provides a view toward understanding the molecular features that determine the spectral properties of cation radicals of carotenoids. The absorption spectral data reveal a shift to longer wavelength with increasing pi-chain length. However, zeaxanthin and beta-cryptoxanthin exhibit cation radical spectra blue-shifted compared to that of beta-carotene, despite all of these molecules having 11 conjugated carbon-carbon double bonds. CIS molecular orbital theory quantum computations interpret this effect as due to the hydroxyl groups in the terminal rings selectively stabilizing the highest occupied molecular orbitals of preferentially populated s-trans-isomers. The data are expected to be useful in the analysis of spectral results from PSII pigment-protein complexes seeking to understand the role of carotene and xanthophyll cation radicals in regulating excited state energy flow, in protecting PSII reaction centers against photoinhibition, and in dissipating excess light energy absorbed by photosynthetic organisms but not used for photosynthesis.

  17. Síntese de copolímeros em bloco de p-acetoxiestireno com isopreno através de polimerização "viva" via radical livre Synthesis of block copolymers from p-acetoxystyrene and isoprene by "living" free radical polymerization

    Directory of Open Access Journals (Sweden)

    José Carlos Moreira

    2004-09-01

    Full Text Available Neste trabalho, é mostrada a síntese de homopolímeros de p-acetoxiestireno e copolímeros diblocos de p-acetoxiestireno com isopreno, utilizando um iniciador TEMPO-modificado, por um processo de polimerização "viva" via radical livre. As análises de GPC indicaram a formação de copolímeros em bloco com massas molares e polidispersão mais altas quando comparadas aos dos homopolímeros correspondentes. Os copolímeros em bloco poli(p-acetoxiestireno-b-isopreno foram preparados com controle de composição e massa molar até 94500 u.m.a. As análises de DSC mostraram que a transição vítrea do bloco de p-acetoxiestireno foi de 5 a 18 °C mais baixa que aquelas obtidas para os homopolímeros correspondentes. A transição vítrea do bloco de isopreno apresentou valores similares àqueles dos homopolímeros de poliisopreno (-67 a -55 °C.In this work we show the synthesis of homopolymers and diblock copolymers of p-acetoxystyrene and isoprene by using TEMPO-modified free radical initiator. The GPC analyses have shown an increase in the molar masses and in the polydispersity of the copolymers in comparison with their corresponding homopolymer. Poly(p-acetoxystyrene-b-isoprene were prepared with good control of composition and molar mass up to 94,500 a.m.u. DSC analyses have shown a glass transition temperature decrease of 5-18 °C for the poly(p-acetoxystyrene segment in copolymers compared to that observed for the parent homopolymer. The glass transition temperature of polyisoprene segment in copolymers remained similar to those observed for the homopolymers (-67 to -55 °C.

  18. Free radical transfer in polymers

    International Nuclear Information System (INIS)

    Sonntag, C. von; Bothe, E.; Ulanski, P.

    1998-01-01

    For the present study of free-radical transfer in polymers pulse radiolysis and product studies have been carried out in aqueous solutions using thus far only the water-soluble polymers polyacrylic acid, polymethacrylic acid and polyvinyl alcohol. When OH radicals, generated in the radiolysis of N 2 O-saturated aqueous solutions, react with polymers the lifetime of the polymer radical thus created very much depends on the number of radicals per polymer chain. When there are a large number of radicals per chain their bimolecular decay may be faster than the corresponding (diffusion controlled) decay of monomeric radicals, but when the macromolecule contains only few or even just one radical their lifetime is considerably prolonged. Highly charged polymers such as polyacrylic acid at high pH attain a rod-like conformation which again favors a long lifetime of the radicals. Under such conditions, radical transfer reactions can occur. For example, in polyacrylic acid OH radicals generate two kinds of radicals side by side. The radical in β-position to the carboxylate group converts into the thermodynamically more stable α-radicals by an H-transfer reaction as can be followed by spectrophotometry. Besides radical transfer reactions β-fragmentation reactions occur causing chain scission. Such reactions can be followed in a pulse radiolysis experiment by conductometry, because counter ions are released upon chain scission. Such a process is especially effective in the case of polymethacrylic acid, where it results in a chain depolymerization. An intramolecular H-abstraction is also observed in the γ-radiolysis of polyacrylic acid with the corresponding peroxyl radicals. This causes a chain reaction to occur. The resulting hydroperoxides are unstable and decarboxylate given rise to acetylacetone-like products. In polyvinyl alcohol the peroxyl radicals in α-position to the alcohol function undergo HO 2 -elimination. This prevents a scission of the polymer chain in the

  19. Muonium-containing vinyl radicals

    International Nuclear Information System (INIS)

    Rhodes, C.J.; Symons, M.C.R.; Roduner, E.; Heming, M.

    1987-01-01

    Exposure of trimethylsilylacetylene and bis(trimethylsilyl)acetylene to positive muons gave radicals whose muon-electron hyperfine coupling constants establish that the corresponding vinyl radicals were formed. (author)

  20. Reaction kinetics of resveratrol with thiyl and alkoxyl radicals

    International Nuclear Information System (INIS)

    Dzeba, I.; Mihaljevic, B.

    2011-01-01

    Complete text of publication follows. Plant derived resveratrol (trans-3,5,4'-trihydroxystilbene) possesses a broad spectrum of biological activities, one of them are very well known its antioxidative properties. Our work aims to provide kinetic data with regard to the reactivity of resveratrol with uninvestigated short-lived bioradicals, identified as mediators in oxidative lipid degradation processes. Radicals of our interest are alkoxyl radicals, well known propagators of the chain free radical reactions in lipids, and thiyl radicals which protect lipids from their degradation pathway, but at the same time cause the isomerization of the double bonds. In order to investigate these reactions of resveratrol laser flash photolysis was used. On the basis of competitive kinetics the rate constants were determined under pseudo-first order conditions in acetonitrile solutions at room temperature. Thiyl radicals were generated indirectly in solution containing 1-octadecanthiol and photosensitive benzophenone in acetonitrile using the light pulses at 347 nm from ruby laser. Tert-butoxyl radicals were generated directly by peroxide bond cleavage from di-tert-butyl peroxide in acetonitrile by light pulses of Nd:YAG at 355 nm, and ruby at 347 nm. Obtained rate constants for the reactions of resveratrol and radicals generated by laser flash photolysis will be summarized and compared with rare literature data for the rate constants of investigated reactions of resveratrol and other radicals generated by pulse radiolysis.

  1. Protonated o-semiquinone radical as a mimetic of the humic acids native radicals: A DFT approach to the molecular structure and EPR properties

    Science.gov (United States)

    Witwicki, Maciej; Jezierska, Julia

    2012-06-01

    Organic radicals are known to be an indispensable component of the humic acids (HA) structure. In HA two forms of radicals, stable (native) and short-lived (transient), are identified. Importantly, these radical forms can be easily differentiated by electron paramagnetic resonance (EPR) spectroscopy. This article provides a DFT-based insight into the electronic and molecular structure of the native radicals. The molecular models including an increase of the radical aromaticity and the hydrogen bonding between the radical and other functional groups of HA are taken under investigation. In consequence the interesting pieces of information on the structure of the native radical centers in HA are revealed and discussed, especially in terms of differences between the electronic structure of the native and transient forms.

  2. Free radical explosive composition

    Science.gov (United States)

    Walker, Franklin E.; Wasley, Richard J.

    1979-01-01

    An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a getter additive comprising a compound or mixture of compounds capable of capturing or deactivating free radicals or ions under mechanical or electrical shock conditions and which is not an explosive. Exemplary getter additives are isocyanates, olefins and iodine.

  3. Trends in radical prostatectomy.

    Science.gov (United States)

    Eastham, James; Tokuda, Yuji; Scardino, Peter

    2009-02-01

    The surgical treatment of prostate cancer ideally removes the entire cancer, avoids excessive blood loss or serious perioperative complications, and results in complete recovery of continence and potency. To achieve this, the surgeon must excise sufficient periprostatic tissue to cure the cancer while preserving the cavernosal nerves required for erectile function and the neuromusculature required for normal urinary and bowel function. Here we will examine recent trends in radical prostatectomy, focusing on surgical technique.

  4. Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

    International Nuclear Information System (INIS)

    Mu Bin; Zhao Mingfei; Liu Peng

    2008-01-01

    Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results

  5. Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Mu Bin; Zhao Mingfei; Liu Peng [Lanzhou University, State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering (China)], E-mail: pliu@lzu.edu.cn

    2008-05-15

    Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results.

  6. Manipulating radicals: Using cobalt to steer radical reactions

    OpenAIRE

    Chirilă, A.

    2017-01-01

    This thesis describes research aimed at understanding and exploiting metallo-radical reactivity and explores reactions mediated by square planar, low-spin cobalt(II) complexes. A primary goal was to uncover novel reactivity of discrete cobalt(III)-bound carbene radicals generated upon reaction of the cobalt(II) catalysts with carbene precursors. Another important goal was to replace cobalt(II)-porphyrin catalysts with cheaper and easier to prepare metallo-radical analogues. Therefore the cata...

  7. Resonance Raman Spectroscopy of Free Radicals Produced by Ionizing Radiation

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter

    1984-01-01

    Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p-nitrobenzylchloride and......Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p......-nitrobenzylchloride and subsequent formation of the p-nitrobenzyl radical and the reaction of p-nitrotoluene with O– are studied by resonance Raman and optical absorption spectroscopy....

  8. Surface-initiated polymerization of 2-hydroxyethyl methacrylate from heterotelechelic oligoperoxide-coated .gamma.-Fe2O3 nanoparticles and their engulfment by mammalian cells

    Czech Academy of Sciences Publication Activity Database

    Horák, Daniel; Shagotova, Tetiana; Mitina, N.; Trchová, Miroslava; Boiko, N.; Babič, Michal; Stoika, R.; Kovářová, Jana; Hevus, O.; Beneš, Milan J.; Klyuchivska, O.; Holler, Petr; Zaichenko, A.

    2011-01-01

    Roč. 23, č. 10 (2011), s. 2637-2649 ISSN 0897-4756 R&D Projects: GA ČR GA203/09/1242; GA ČR GAP503/10/0664; GA AV ČR(CZ) KAN401220801 Institutional research plan: CEZ:AV0Z40500505 Keywords : 2-hydroxyethyl methacrylate * oligoperoxide * surface-initiated polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 7.286, year: 2011

  9. Hydroxyl radical reactivity with diethylhydroxylamine

    International Nuclear Information System (INIS)

    Gorse, R.A. Jr.; Lii, R.R.; Saunders, B.B.

    1977-01-01

    Diethylhydroxylamine (DEHA) reacts with gas-phase hydroxyl radicals on every third collision, whereas the corresponding reaction in aqueous solution is considerably slower. The high gas-phase reactivity explains the predicted inhibitory effect of DEHA in atmospheric smog processes. Results from the studies in the aqueous phase are helpful in predicting the mechanism of the reaction of DEHA with hydroxyl radicals

  10. Muoniated acyl and thioacyl radicals

    International Nuclear Information System (INIS)

    McKenzie, Iain; Brodovitch, Jean-Claude; Ghandi, Khashayar; Percival, Paul W.

    2006-01-01

    The product of the reaction of muonium with tert-butylisocyanate was previously assigned as the muoniated tert-butylaminyl radical (I. McKenzie, J.-C. Brodovitch, K. Ghandi, S. Kecman, P. W. Percival, Physica B 326 (2003) 76). This assignment is incorrect since the muon and 14 N hyperfine-coupling constants (hfcc) of this radical would have the opposite sign, which is in conflict with the experimental results. The radical is now reassigned as the muoniated N-tert-butylcarbamoyl radical, based on the similarities between the experimental muon and 14 N hfcc and hfcc calculated at the UB3LYP/6-311G(d,p)//UB3LYP/EPR-III level. The large zero-point energy in the N-Mu bond results in the dissociation barrier of the muoniated N-tert-butylcarbamoyl radical being above the combined energy of the reactants, in contrast to the N-tert-butylcarbamoyl radical where the dissociation barrier lies below the combined energy of the reactants. The reaction of muonium with tert-butylisothiocyanate produced both conformers of the muoniated N-tert-butylthiocarbamoyl radical and their assignment was based on the similarities between the experimental and calculated muon hfcc. These are the first acyl and thioacyl radicals to be directly detected by muon spin spectroscopy

  11. Muoniated acyl and thioacyl radicals

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, Iain [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); Brodovitch, Jean-Claude [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); Ghandi, Khashayar [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); Percival, Paul W. [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada)]. E-mail: percival@sfu.ca

    2006-03-31

    The product of the reaction of muonium with tert-butylisocyanate was previously assigned as the muoniated tert-butylaminyl radical (I. McKenzie, J.-C. Brodovitch, K. Ghandi, S. Kecman, P. W. Percival, Physica B 326 (2003) 76). This assignment is incorrect since the muon and {sup 14}N hyperfine-coupling constants (hfcc) of this radical would have the opposite sign, which is in conflict with the experimental results. The radical is now reassigned as the muoniated N-tert-butylcarbamoyl radical, based on the similarities between the experimental muon and {sup 14}N hfcc and hfcc calculated at the UB3LYP/6-311G(d,p)//UB3LYP/EPR-III level. The large zero-point energy in the N-Mu bond results in the dissociation barrier of the muoniated N-tert-butylcarbamoyl radical being above the combined energy of the reactants, in contrast to the N-tert-butylcarbamoyl radical where the dissociation barrier lies below the combined energy of the reactants. The reaction of muonium with tert-butylisothiocyanate produced both conformers of the muoniated N-tert-butylthiocarbamoyl radical and their assignment was based on the similarities between the experimental and calculated muon hfcc. These are the first acyl and thioacyl radicals to be directly detected by muon spin spectroscopy.

  12. The mitochondrial free radical theory of aging.

    Science.gov (United States)

    Barja, Gustavo

    2014-01-01

    The mitochondrial free radical theory of aging is reviewed. Only two parameters currently correlate with species longevity in the right sense: the mitochondrial rate of reactive oxygen species (mitROS) production and the degree of fatty acid unsaturation of tissue membranes. Both are low in long-lived animals. In addition, the best-known manipulation that extends longevity, dietary restriction, also decreases the rate of mitROS production and oxidative damage to mtDNA. The same occurs during protein restriction as well as during methionine restriction. These two manipulations also increase maximum longevity in rodents. The decrease in mitROS generation and oxidative stress that takes place in caloric restriction seems to be due to restriction of a single dietary substance: methionine. The information available supports a mitochondrial free radical theory of aging focused on low generation of endogenous damage and low sensitivity of membranes to oxidation in long-lived animals. © 2014 Elsevier Inc. All rights reserved.

  13. The role of proteins in damage induced by free radicals

    International Nuclear Information System (INIS)

    Gebicki, J.M.

    1996-01-01

    The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 μM Cu ++ , and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe ++ . If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage

  14. The role of proteins in damage induced by free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Gebicki, J.M. [Macquarie Univ., North Ryde, NSW (Australia). School of Biological Sciences

    1996-12-31

    The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 {mu}M Cu{sup ++}, and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe{sup ++}. If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage.

  15. Radically Healing Black Lives: A Love Note to Justice.

    Science.gov (United States)

    Ginwright, Shawn A

    2015-01-01

    This chapter describes how present conditions in Black communities have fostered the development of new modes of youth leadership that focus on hope, love, and joy, and are ultimately restorative and redemptive. © 2015 Wiley Periodicals, Inc., A Wiley Company.

  16. Radical production in biological systems

    International Nuclear Information System (INIS)

    Johnson, J.R.; Akabani, G.

    1994-10-01

    This paper describes our effort to develop a metric for radiation exposure that is more fundamental than adsorbed dose and upon which a metric for exposure to chemicals could be based. This metric is based on the production of radicals by the two agents. Radicals produced by radiation in biological systems commonly assumed to be the same as those produced in water despite the presence of a variety of complex molecules. This may explain why the extensive efforts to describe the relationship between energy deposition (track structure) and molecular damage to DNA, based on the spectrum of radicals produced, have not been successful in explaining simple biological effects such as cell killing. Current models assume that DNA and its basic elements are immersed in water-like media and only model the production and diffusion of water-based radicals and their interaction with DNA structures; these models lack the cross sections associated with each macro-component of DNA and only treat water-based radicals. It has been found that such models are not realistic because DNA is not immersed in pure water. A computer code capable of simulating electron tracks, low-energy electrons, energy deposition in small molecules, and radical production and diffusion in water like media has been developed. This code is still in at a primitive stage and development is continuing. It is being used to study radical production by radiation, and radical diffusion and interactions in simple molecular systems following their production. We are extending the code to radical production by chemicals to complement our PBPK modeling efforts. It therefore has been developed primarily for use with radionuclides that are in biological materials, and not for radiation fields

  17. Guest Editorial: Processes of Radicalization and De-Radicalization

    Directory of Open Access Journals (Sweden)

    Donatella Della Porta

    2012-05-01

    Full Text Available The study of radicalization and de-radicalization, understood as processes leading towards the increased or decreased use of political violence, is central to the question of how political violence emerges, how it can be prevented, and how it can be contained. The focus section of this issue of the International Journal of Conflict and Violence addresses radicalization and de-radicalization, seeking to develop a more comprehensive understanding of the processes, dynamics, and mechanisms involved and taking an interdisciplinary approach to overcome the fragmentation into separate disciplines and focus areas. Contributions by Pénélope Larzillière, Felix Heiduk, Bill Kissane, Hank Johnston, Christian Davenport and Cyanne Loyle, Veronique Dudouet, and Lasse Lindekilde address repressive settings, legitimacy, institutional aspects, organizational outcomes, and dynamics in Europe, Asia, Africa, and North and South America.

  18. Redox properties of free radicals

    International Nuclear Information System (INIS)

    Neta, P.

    1981-01-01

    Results of electron transfer reactions observed and monitored by pulse radiolysis are reported. This technique allows determination of the first one-electron reduction or oxidation of a compound rather than the overall two-electron transfer usually reported. Pulse radiolysis allows the determination of absolute rate constants for reactions of free radicals and helps elucidate the mechanisms involved. Studies using this technique to study radicals derived from quinones, nitro compounds, pyridines, phenols, and anilines are reported. Radicals of biochemical interest arising from riboflavin, ascorbic acid, vitamin K 3 , vitamin E, MAD + , porphyrins, etc. have also been studied

  19. Hot wire radicals and reactions

    International Nuclear Information System (INIS)

    Zheng Wengang; Gallagher, Alan

    2006-01-01

    Threshold ionization mass spectroscopy is used to measure radical (and stable gas) densities at the substrate of a tungsten hot wire (HW) reactor. We report measurements of the silane reaction probability on the HW and the probability of Si and H release from the HW. We describe a model for the atomic H release, based on the H 2 dissociation model. We note major variations in silicon-release, with dependence on prior silane exposure. Measured radical densities versus silane pressure yield silicon-silane and H-silane reaction rate coefficients, and the dominant radical fluxes to the substrate

  20. CONTINENT RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    Yu. P. Sernyak

    2013-01-01

    Full Text Available Objective: to evaluate the impact of dissection of the dorsal venous complex without pre-ligation, suturing, or coagulation during radical prostatectomy (RPE in patients with localized prostate cancer (PC on the quality of surgery and the function of urinary retention.Subjects and methods. The data of 42 patients who had undergone posterior and anterior anatomical repair and vesicourethral anastomosis using a V-lock suture after prostatectomy were analyzed. All the patients were divided into 2 groups. Group 1 consisted of 22 patients in whom the dorsal venous complex was closed using a 3-0 vicryl suture before urethral dissection. Group 2 included 20 patients in whom the urethra was dissected without suturing the venous complex.Results. In group 1, complete urinary retention after catheter removal was noted in 9 (40.9 % and 15 (68 % patients within 24 hours and after 3 months, respectively. Following 12 months, two (9 % patients were observed to have partial mild urinary incontinence (as many as 2 pads per day. Group 2 patients showed complete urinary retention in 17 (85 % cases on the first day after catheter removal; all the patients retained urine 3 months later.Conclusion. In patients with localized PC, dissection of the dorsal venous complex without presuturing during laparoscopic RPE exerts a considerable impact on the preservation of urinary retention, namely 45% more of the patients reported complete urinary retention in early periods and 10 % more did this in later periods. At the same time, there was no statistically significant increase in intraoperative blood loss (p > 0.05, the number of positive edges, or biochemical recurrences.

  1. CONTINENT RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    Yu. P. Sernyak

    2014-07-01

    Full Text Available Objective: to evaluate the impact of dissection of the dorsal venous complex without pre-ligation, suturing, or coagulation during radical prostatectomy (RPE in patients with localized prostate cancer (PC on the quality of surgery and the function of urinary retention.Subjects and methods. The data of 42 patients who had undergone posterior and anterior anatomical repair and vesicourethral anastomosis using a V-lock suture after prostatectomy were analyzed. All the patients were divided into 2 groups. Group 1 consisted of 22 patients in whom the dorsal venous complex was closed using a 3-0 vicryl suture before urethral dissection. Group 2 included 20 patients in whom the urethra was dissected without suturing the venous complex.Results. In group 1, complete urinary retention after catheter removal was noted in 9 (40.9 % and 15 (68 % patients within 24 hours and after 3 months, respectively. Following 12 months, two (9 % patients were observed to have partial mild urinary incontinence (as many as 2 pads per day. Group 2 patients showed complete urinary retention in 17 (85 % cases on the first day after catheter removal; all the patients retained urine 3 months later.Conclusion. In patients with localized PC, dissection of the dorsal venous complex without presuturing during laparoscopic RPE exerts a considerable impact on the preservation of urinary retention, namely 45% more of the patients reported complete urinary retention in early periods and 10 % more did this in later periods. At the same time, there was no statistically significant increase in intraoperative blood loss (p > 0.05, the number of positive edges, or biochemical recurrences.

  2. Surface modification of nanodiamond through metal free atom transfer radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Deng, Fengjie, E-mail: fengjiedeng@aliyun.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China)

    2016-12-30

    Highlights: • Surface modification of ND with water soluble and biocompatible polymers. • Functionalized ND through metal free surface initiated ATRP. • The metal free surface initiated ATRP is rather simple and effective. • The ND-poly(MPC) showed high dispersibility and desirable biocompatibility. - Abstract: Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by {sup 1}H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

  3. Surface modification of nanodiamond through metal free atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2016-01-01

    Highlights: • Surface modification of ND with water soluble and biocompatible polymers. • Functionalized ND through metal free surface initiated ATRP. • The metal free surface initiated ATRP is rather simple and effective. • The ND-poly(MPC) showed high dispersibility and desirable biocompatibility. - Abstract: Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by 1 H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

  4. Radical Change by Entrepreneurial Design

    National Research Council Canada - National Science Library

    Roberts, Nancy C

    1998-01-01

    .... Radical change by entrepreneurial design then becomes the focal point, in order to acquaint the reader with the strategies and tactics of well-known entrepreneurs who have been successful in molding...

  5. Penile rehabilitation after radical prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Ohl, Dana A; Ralph, David

    2013-01-01

    The pathophysiology of erectile dysfunction after radical prostatectomy (RP) is believed to include neuropraxia, which leads to temporarily reduced oxygenation and subsequent structural changes in penile tissue. This results in veno-occlusive dysfunction, therefore, penile rehabilitation programmes...

  6. Radical prostatectomy. Results and indications

    International Nuclear Information System (INIS)

    Jacqmin, D.

    1997-01-01

    Radical prostatectomy is the surgical curative treatment of localized prostate cancer. The survival is good in young patients (<70) with T2 N0M0 tumors and more than 10 year's life expectancy. Side-effects are urinary incontinence, impotence and anastomosis stricture. Quality of life should be considered as an important factor for the choice of the patient between radical prostatectomy, radiotherapy and follow-up. (author)

  7. Radical Islamism and Failed Developmentalism

    OpenAIRE

    Rahnema, Saeed

    2008-01-01

    The rise of radical Islamism in recent years does not limit the applicability of the concept of cultural nationalism. Rather the two are intertwined in ways which this article will attempt to highlight. Islam took specific national forms as modern nation-states arose and the contemporary resurgence of radical Islamism also follows that modern pattern. I examine the emergence of the three most important movements in the Islamic world, namely, the Muslim Brotherhood in Egypt, Jama'at-e Islami i...

  8. Spin relaxation of radicals in cryptochrome and its role in avian magnetoreception

    Energy Technology Data Exchange (ETDEWEB)

    Worster, Susannah; Kattnig, Daniel R.; Hore, P. J., E-mail: peter.hore@chem.ox.ac.uk [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ (United Kingdom)

    2016-07-21

    Long-lived spin coherence and rotationally ordered radical pairs have previously been identified as key requirements for the radical pair mechanism of the avian magnetic compass sense. Both criteria are hard to meet in a biological environment, where thermal motion of the radicals creates dynamic disorder and drives efficient spin relaxation. This has long been cited as a major stumbling block of the radical pair hypothesis. Here we combine Redfield relaxation theory with analytical solutions to a rotational diffusion equation to assess the impact of restricted rotational motion of the radicals on the operation of the compass. The effects of such motions are first investigated generally in small, model systems and are then critically examined in the magnetically sensitive flavin-tryptophan radical pair that is formed photochemically in the proposed magnetoreceptor protein, cryptochrome. We conclude that relaxation is slowest when rotational motion of the radicals within the protein is fast and highly constrained; that in a regime of slow relaxation, the motional averaging of hyperfine interactions has the potential to improve the sensitivity of the compass; and that consideration of motional effects can significantly alter the design criteria for an optimal compass. In addition, we demonstrate that motion of the flavin radical is likely to be compatible with its role as a component of a functioning radical-pair compass, whereas the motion of the tryptophan radical is less ideal, unless it is particularly fast.

  9. Laparoscopic radical cystectomy: key points

    Directory of Open Access Journals (Sweden)

    D. V. Perlin

    2018-01-01

    Full Text Available Background. Radical cystectomy remains the golden standard for treatment of muscle invasive bladder cancer. Objective: to duplicate with highest accuracy the open radical cystectomy procedure, which we successfully utilized earlier in our clinic, in the of laparoscopic conditions in order to preserve the advantages of minimally invasive procedures and retain the reliability of the tried and tested open surgery.Materials and methods. In the report were included 35 patients (27 men and 8 women with bladder cancer, who underwent laparoscopic radical cystectomy in Volgograd Regional Center of Urology and Nephrology between April 2013 and March 2016. Only the patients who had been submitted to full intracorporal ileal conduits were included.Results. The mean operative time was 378 minutes, the mean blood loss was 285 millilitres, the mean length of hospital stay was 12.4 days, only 20 % of patients required the narcotic anesthetics. The postoperative complication rate was 11.4 %. However, the majority of the patients were successfully treated with minimally invasive procedures. Generally, our results were similar to other reported studies.Conclusion. Laparoscopic radical cystectomy is a safe and efficient modality of treatment of bladder cancer. However, it needs more procedures and longer observation period to establish laparoscopic radical cystectomy as an alternative to open radical cystectomy.

  10. Fluoropolymer materials and architectures prepared by controlled radical polymerizations

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie; Jankova Atanasova, Katja; Hvilsted, Søren

    2007-01-01

    This review initially summarizes the mechanisms, merits and limitations of the three controlled radical polymerizations: nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP) or metal catalyzed living radical polymerization, and reversible addition–fragmentation chain...... transfer (RAFT) polymerization. This is followed by two parts, one dealing with homo- and copolymerizations of fluorinated methacrylates and acrylates, and a second where fluorinated styrenes, alone or in combination with other monomers, are the main issues. In these parts, initiators (including...... properties and functionalities that can be obtained from these novel fluorinated materials and architectures are especially emphasized. Thus, various amphiphilic, biocompatible or low energy materials, fluorinated nanoparticles and nanoporous films/membranes as well as materials for submicron and nanolevel...

  11. Synergy between low and high energy radical femtochemistry

    International Nuclear Information System (INIS)

    Gauduel, Y A

    2011-01-01

    The deleterious effects of ionizing radiation on integrated biological targets being dependent on the spatio-temporal distribution of short-lived radical processes, a thorough knowledge of these early events requires a real-time probing in the range 10 -15 - 10 -10 s. This manuscript review is focused on the synergy that exists between low (1-10 eV) and high (MeV) energy radiation femtochemistry (LERF, HERF respectively). The synergy remains crucial for the investigation of primary radical processes that take place within the prethermal regime of low energy secondary electrons. The quantum character of very-short lived electron in a prehydrated configuration provides a unique sub-nanometric probe to spatially explore some early radiation-induced biomolecular damage. This approach would foreshadow the development of innovative applications for spatio-temporal radiation biology such as, i) a highly-selective pro-drug activation using well-defined quantum states of short-lived radicals, ii) the real-time nanodosimetry in biologically relevant environments, and iii) the ultrashort irradiation of living cells.

  12. Healthy Living

    Science.gov (United States)

    ... Health Menu Topics Environment & Health Healthy Living Pollution Reduce, Reuse, Recycle Science – How It Works The Natural World Games ... Lessons Topics Expand Environment & Health Healthy Living Pollution Reduce, Reuse, Recycle Science – How It Works The Natural World Games ...

  13. The Prospects of Radical Change Today

    Directory of Open Access Journals (Sweden)

    Slavoj Žižek

    2018-05-01

    Full Text Available In this contribution, Slavoj Žižek takes the occasion of Marx’s bicentenary for reflecting on the prospects of radical change today. First, it is shown that under Stalinism, Lenin’s works were quoted out of context in an arbitrary way in order to legitimise arbitrary political measures. Marxism thereby became an ideology that justified brutal subjective interventions. Second, this contribution poses the question of the revolutionary subject and democracy today. It stresses the role of both contingency and strategy in revolutions. In political assemblages taking place on public squares, the inert mass of ordinary people is transubstantiated into a politically engaged united force. The basic political problem today is how to best reconfigure democracy. Third, this contribution analyses the “interesting times” we live in. These are times that feature multiple crises, right-wing populism à la Donald Trump and Marine Le Pen, the lower classes’ opposition to immigration, and the refugee crisis. Questions about human rights and their violation and about radical change need to be asked in this context.

  14. Assisted Living

    Science.gov (United States)

    ... it, too. Back to top What is the Cost for Assisted Living? Although assisted living costs less than nursing home ... Primarily, older persons or their families pay the cost of assisted living. Some health and long-term care insurance policies ...

  15. Mechanisms of free radical-induced damage to DNA.

    Science.gov (United States)

    Dizdaroglu, Miral; Jaruga, Pawel

    2012-04-01

    Endogenous and exogenous sources cause free radical-induced DNA damage in living organisms by a variety of mechanisms. The highly reactive hydroxyl radical reacts with the heterocyclic DNA bases and the sugar moiety near or at diffusion-controlled rates. Hydrated electron and H atom also add to the heterocyclic bases. These reactions lead to adduct radicals, further reactions of which yield numerous products. These include DNA base and sugar products, single- and double-strand breaks, 8,5'-cyclopurine-2'-deoxynucleosides, tandem lesions, clustered sites and DNA-protein cross-links. Reaction conditions and the presence or absence of oxygen profoundly affect the types and yields of the products. There is mounting evidence for an important role of free radical-induced DNA damage in the etiology of numerous diseases including cancer. Further understanding of mechanisms of free radical-induced DNA damage, and cellular repair and biological consequences of DNA damage products will be of outmost importance for disease prevention and treatment.

  16. CRITICAL THEORY OF THE RADICAL LOVE

    Directory of Open Access Journals (Sweden)

    Lena de Botton

    2009-11-01

    Full Text Available The understanding of the sexual-affective relationships has historically notbeen tackled by science, but placed in the context of instincts and irrationality. In thissense, the critical theory of the Radical Love provides a contribution to critical pedagogyallowing people to understand the mechanisms that direct their emotions and theprocess of election in the sexual-affective relationships. It is about understanding whodo we fall in love for, why and to which values is this desire linked being able to have agreat repercussion in our lives as it provides us with the tools to develop satisfactorysexual-affective relationships. It also offers us guidelines for a preventive educationregarding gender violence by enabling us to understand the attraction models in whichwe have been socialised and which are influencing our desire and elections.

  17. Conversion of alkyl radicals to allyl radicals in irradiated single crystal mats of polyethylene

    International Nuclear Information System (INIS)

    Fujimura, T.; Hayakawa, N.; Kuriyama, I.

    1978-01-01

    The decay of alkyl radicals, the conversion of alkyl radicals to allyl radicals and the trapping of allyl radicals in irradiated single crystal mats of polyethylene have been studied by electron spin resonance (e.s.r.). It has been suggested that in the crystal core alkyl radicals react with trans-vinylene double bonds and are converted into trans-vinylene allyl radicals; at the crystal surface, alkyl radicals react with vinyl end groups and are converted into allyl radicals with vinyl end groups. The decay of radical pairs and the formation of trans-vinylene double bonds are discussed. (author)

  18. 17.9.3 Radical cations of diazo compounds

    Science.gov (United States)

    Davies, A. G.

    This document is part of Subvolume E2 `Phosphorus-Centered Radicals, Radicals Centered on Other Heteroatoms, Organic Radical Ions' of Volume 26 `Magnetic Properties of Free Radicals' of Landolt-Börnstein Group II `Molecules and Radicals'.

  19. Effect of metal complexation to anti-inflammatory over the action against oxidative and free radicals: ketoprofen action

    International Nuclear Information System (INIS)

    Manente, Francine Alessandra; Mello, Lucas Rosolen de Almeida; Vellosa, Jose Carlos Rebuglio; Khalil, Omar Arafat Kdudsi; Carvalho, Claudio Teodoro de; Bannach, Gilbert

    2011-01-01

    Free radicals are highly reactive species generated in living organisms for the purpose of protection. However, in some circumstances, they are responsible for the occurrence or aggravation of tissue damage. Many anti-inflammatory drugs have a direct effect on free radicals and not radical reactive species, which contributes to its actions against inflammation. Ketoprofen is a nonsteroidal anti-inflammatory agent that generates free radicals by photo irradiation and has an important hemolytic effect with that. The complexation of metals to different drugs has been used as a strategy to improve the pharmacological action of different molecules and reduce their side effects. This paper presents the results of ketoprofen and their metallic complexes action on erythrocytes and free radicals. It was observed that the cerium enhances the scavenger properties of ketoprofen on free radicals, while copper enhances its action over non-radical oxidants. Copper also reduced the hemolytic effect presented by ketoprofen meanwhile its cerium derivative maintained it. (author)

  20. Living Technology

    DEFF Research Database (Denmark)

    2010-01-01

    This book is aimed at anyone who is interested in learning more about living technology, whether coming from business, the government, policy centers, academia, or anywhere else. Its purpose is to help people to learn what living technology is, what it might develop into, and how it might impact...... our lives. The phrase 'living technology' was coined to refer to technology that is alive as well as technology that is useful because it shares the fundamental properties of living systems. In particular, the invention of this phrase was called for to describe the trend of our technology becoming...... increasingly life-like or literally alive. Still, the phrase has different interpretations depending on how one views what life is. This book presents nineteen perspectives on living technology. Taken together, the interviews convey the collective wisdom on living technology's power and promise, as well as its...

  1. Photoionization of the OH radical

    International Nuclear Information System (INIS)

    Dehmer, P.M.

    1985-01-01

    The hydroxyl radical (OH) is one of the most thoroughly studied free radicals because of its importance in atmospheric chemistry, combustion processes, and the interstellar medium. Detailed experimental and theoretical studies have been performed on the ground electronic state (X 2 PI/sub i/) and on the four lowest bound excited electronic states (A 2 Σ + , B 2 Σ + , D 2 Σ - , and C 2 Σ + ). However, because it is difficult to distinguish the spectrum of OH from the spectra of the various radical precursors, the absorption spectrum in the wavelength region below 1200 A has not been well characterized. In the present work, the spectrum of OH has been determined in the wavelength region from 750 to 950 A using the technique of photoionization mass spectrometry. This technique allows complete separation of the spectrum of OH from that of the other components of the discharge and permits the unambiguous determination of the spectrum of OH

  2. Radical-Mediated Enzymatic Polymerizations

    Science.gov (United States)

    Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

    2016-01-01

    Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

  3. Donor free radical explosive composition

    Science.gov (United States)

    Walker, Franklin E. [15 Way Points Rd., Danville, CA 94526; Wasley, Richard J. [4290 Colgate Way, Livermore, CA 94550

    1980-04-01

    An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a donor additive comprising an organic compound or mixture of organic compounds capable of releasing low molecular weight free radicals or ions under mechanical or electrical shock conditions and which is not an explosive, or an inorganic compound or mixture of inorganic compounds capable of releasing low molecular weight free radicals or ions under mechanical or electrical shock conditions and selected from ammonium or alkali metal persulfates.

  4. Radical feminists & trans activists truce

    OpenAIRE

    Mackay, F.

    2014-01-01

    #GenderWeek: Truce! When radical feminists and trans feminists empathise\\ud Feminist Times\\ud By Finn Mackay \\ud read all #GenderWeek articles.\\ud We wanted to explore the ground between the polarised, entrenched positions in the so-called “TERF-war”. Radical feminists on one pole, trans-inclusionary feminists and trans activists on the other. The disputed territory being women-only space, language and the ever changing legal framework surrounding gender.\\ud Entrenchment leads to stalemate. S...

  5. Radical and Not So Radical Transgressions: Invading Backstage Domains

    Directory of Open Access Journals (Sweden)

    Lada Čale Feldman

    2012-06-01

    Full Text Available Featuring as one of the privileged metaphors in humanities and social sciences, theatre provides primarily an image of a circumscribed space whose spatial syntax and modes of human engagement take place within and with respect to the larger space of the city, the world, and, as in Calderon’s Gran teatro del mundo, the universe. It is precisely as a special organization of spatiality that theatre reached the status of Foucault’s radical hetero-topos, flexible as it proved to be as a model for not only counter-representing all the human dealings in the external space, but also of conceptualizing, as in Freud’s psychoanalysis, man’s inner world, his psychic topography. But theatre is above all a concrete place, a built form with its own spatial history, its changing social and ideological functions, and its ways of bestowing to the bodies that enter into it actual or phantasm identities, thoughts, sensations, feelings and memories.My intervention will deal with one of the ruling borders/dichotomies/barriers of theatrical space, the one dividing “front stage” from “backstage” regions. In his detailed analysis of the latter in an individual and concrete theatre building, Andrew Filmer relies among others on Edward Soja’s “trialectics of being”, and thus also on Lefebvre’s categories of perceptual, conceptual and lived aspects of spatiality which Soja evokes, which will here be of particular interest. In contrast to the repercussions of such an analytical triad for the ethnographic study of concrete theatrical sites, I will ask how it pertains to potential manipulations of the aforementioned division of front-stage and backstage within contemporary performance practice. The temporal aspect of this manipulation should also be emphasized, having in mind the historical provenance of a whole backstage mythology – evidenced in numerous novels, plays and films situated in the backstage world - in the elaborated architectural

  6. Structure and dynamics of olefin radical cation aggregates. Time-resolved fluorescence detected magnetic resonance

    International Nuclear Information System (INIS)

    Desrosiers, M.F.; Trifunac, A.D.

    1986-01-01

    The time-resolved EPR spectra and thus the structure and dynamics of transient hydrocarbon radical cations are obtained by the pulse radiolysis-fluorescence detected magnetic resonance (FDMR) technique. Here the authors report the observation of short-lived radical cations from olefins. FDMR-EPR spectra of radical cations from tetramethylethylene and cyclohexadiene are illustrated. The olefin radical cations, FDMR spectra are concentration-dependent, since dimerization with neutral molecules takes place at higher (>10 -2 M) olefin concentration. Rate constants for the dimerization reaction are derived and the effect of solvent viscosity on aggregate formation is demonstrated. By monitoring the further reactions of dimer cations the authors have obtained EPR evidence for previously unobserved higher-order (multimer) radical cation aggregates of olefins. 16 references, 5 figures

  7. Reaction between protein radicals and other biomolecules

    DEFF Research Database (Denmark)

    Østdal, H.; Davies, M.J.; Andersen, Henrik Jørgen

    2002-01-01

    The present study investigates the reactivity of bovine serum albumin (BSA) radicals towards different biomolecules (urate, linoleic acid, and a polypeptide, poly(Glu-Ala-Tyr)). The BSA radical was formed at room temperature through a direct protein-to-protein radical transfer from H(2)O(2....... Subsequent analysis showed a decrease in the concentration of urate upon reaction with the BSA radical, while the BSA radical in the presence of poly(Glu-Ala-Tyr) resulted in increased formation of the characteristic protein oxidation product, dityrosine. Reaction between the BSA radical and a linoleic acid...

  8. Laparoscopically assisted vaginal radical trachelectomy

    International Nuclear Information System (INIS)

    Bielik, T.; Karovic, M.; Trska, R.

    2013-01-01

    Purpose: Radical trachelectomy is a fertility-sparing procedure with the aim to provide adequate oncological safety to patients with cervical cancer while preserving their fertility. The purpose of this study was to retrospectively evaluate, in a series of 3 patients, the feasibility, morbidity, and safety of laparoscopically assisted vaginal radical trachelectomy for early cervical cancer. Patients and Methods: Three non consecutive patients with FIGO stage IA1 and IB1 cervical cancer was evaluated in a period of years 2008 - 2011. The patients underwent a laparoscopic pelvic lymphadenectomy and radical parametrectomy class II procedure according to the Piver classification. The section of vaginal cuff, trachelectomy, permanent cerclage and isthmo-vaginal anastomosis ware realised by vaginal approach. Results: The median operative time, the median blood loss and the mean number of resected pelvic nodes was comparable with published data. Major intraoperative complications did not occur and no patient required a blood transfusion. The median follow-up time was 33 (38-59) months. One vaginal recurrence occurred in 7 months after primary surgery. The patient was underwent a radicalisation procedure and adjuvant oncologic therapy and now is free of disease. Conclusions: Laparoscopically assisted vaginal radical trachelectomy (LAVRT)may be an alternative in fertility-preserving surgery for early cervical cancer. The procedure offers patients potential benefits of minimally invasive surgery with adequate oncological safety, but it should be reserved for oncologic surgeons trained in advanced laparoscopic procedures. (author)

  9. Is Radical Innovation Management Misunderstood?

    DEFF Research Database (Denmark)

    Kristiansen, Jimmi Normann; Gertsen, Frank

    2015-01-01

    This paper poses a critical view on radical innovation (RI) management research and practice. The study investigates how expected RI performance influences firms’ under- standing of their RI capability. RI performance is often based on output measures such as market shares or fiscal return...

  10. Exploring the Theories of Radicalization

    Directory of Open Access Journals (Sweden)

    Maskaliūnaitė Asta

    2015-12-01

    Full Text Available After the London bombings in July 2005, the concern of terrorism scholars and policy makers has turned to “home-grown” terrorism and potential for political violence from within the states. “Radicalization” became a new buzz word. This article follows a number of reviews of the literature on radicalization and offers another angle for looking at this research. First, it discusses the term “radicalization” and suggests the use of the following definition of radicalization as a process by which a person adopts belief systems which justify the use of violence to effect social change and comes to actively support as well as employ violent means for political purposes. Next, it proposes to see the theories of radicalization focusing on the individual and the two dimensions of his/her motivation: whether that motivation is internal or external and whether it is due to personal choice or either internal (due to some psychological traits or external compulsion. Though not all theories fall neatly within these categories, they make it possible to make comparisons of contributions from a variety of different areas thus reflecting on the interdisciplinary nature of the study of terrorism in general and radicalization as a part of it.

  11. Ultrasound-induced radical polymerization

    NARCIS (Netherlands)

    Kuijpers, M.W.A.; Kemmere, M.F.; Keurentjes, J.T.F.

    2004-01-01

    Sonochemistry comprises all chemical effects that are induced by ultrasound. Most of these effects are caused by cavitations, ie, the collapse of microscopic bubbles in a liquid. The chemical effects of ultrasound include the formation of radicals and the enhancement of reaction rates at ambient

  12. Erectile function after radical prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Frey, Anders; Jakobsen, Henrik

    2016-01-01

    collected database and a cross-sectional, questionnaire-based study in patients following radical prostatectomy. Erectile function was assessed with the IIEF-5 and the question "Is your erectile function as good as before the surgery (yes/no)". Patients were included if they were sexually active before...

  13. Getting to know patients’ lived space

    DEFF Research Database (Denmark)

    Norlyk, Annelise; Martinsen, Bente; Dahlberg, Karen

    2013-01-01

    .g. the role of the good patient and the ambiance of hospitals. Home, on the other hand, offers familiar lived space in which patients feel protected and safe. Further, the paper relates patients’ experience of lived space to a phenomenological view of lived space in order to illustrate the radical influence...... as a theoretical framework for an excursive analysis. The paper demonstrates that existential dimensions of lived space at the hospital and at home differ significantly. For the patients, the hospital space means alien territory as opposed to the familiar territory of home. To some extent the experienced...

  14. Live Well

    Science.gov (United States)

    ... Health Conditions Live Well Mental Health Substance Use Smoking Healthy Diet Physical Activity Family Planning Living with HIV: Travel ... to his or her health and well-being. Smoking - Tobacco use is the ... year. Healthy Diet - No matter your HIV status, healthy eating is ...

  15. Healthy living

    Science.gov (United States)

    ... living URL of this page: //medlineplus.gov/ency/article/002393.htm Healthy living To use the sharing features on this page, please enable JavaScript. Good health habits can allow you to avoid illness and improve your quality of life. The following steps will help you ...

  16. Catalase expression is modulated by vancomycin and ciprofloxacin and influences the formation of free radicals in Staphylococcus aureus cultures

    DEFF Research Database (Denmark)

    Wang, Ying; Hougaard, Anni Bygvrå; Paulander, Wilhelm Erik Axel

    2015-01-01

    Detection of free radicals in biological systems is challenging due to their short half-lives. We have applied electron spin resonance (ESR) spectroscopy combined with spin traps using the probes PBN (N-tert-butyl-α-phenylnitrone) and DMPO (5,5-dimethyl-1-pyrroline N-oxide) to assess free radical...... that in S. aureus, bactericidal antibiotics modulate catalase expression, which in turn influences the formation of free radicals in the surrounding broth medium. If similar regulation is found in other bacterial species, it might explain why bactericidal antibiotics are perceived as inducing formation...... of free radicals....

  17. Flavonoids as scavengers of nitric oxide radical.

    NARCIS (Netherlands)

    van Acker, S.A.B.E.; Tromp, M.N.J.L.; Haenen, G.R.M.M.; van der Vijgh, W.J.F.; Bast, A.

    1995-01-01

    Flavonoids are a group of naturally occurring compounds used, e.g., in the treatment of vascular endothelial damage. They are known to be excellent scavengers of oxygen free radicals. Since the nitric oxide radical (

  18. O conceito de mal radical The concept of radical evil

    Directory of Open Access Journals (Sweden)

    Adriano Correia

    2005-01-01

    Full Text Available A noção de mal radical aparece em Kant no contexto da discussão da religião nos limites da simples razão e busca dar conta da complexa relação entre o respeito pela lei moral e o amor-próprio na definição do móbil para a ação. Na busca por identificar o fundamento da propensão para o mal no homem, Kant se vê diante da dificuldade de ter de articular natureza e liberdade, e ainda que a noção de mal radical possa conservar algumas ambigüidades, permite conceber uma noção de responsabilidade compatível com uma inata propensão para o mal. Neste texto busco explicitar alguns passos fundamentais na construção do conceito por Kant.The concept of radical evil appears in Kant's theory when he discusses the religion in the limits of the mere reason and aims explain the complex relationship between respect for the moral law and the self-love, for establish the motive of the action. By aiming identify the basis of human inclination to evil, Kant is faced with the trouble of have to put nature and freedom in connection. Despite of the concept of radical evil retain some ambiguity, it allows conceive a notion of responsibility suitable to an inherent inclination to evil. In this paper is my purpose to explain some basic moments of Kantian formulation of that notion.

  19. Free radicals in chemical carcinogenesis.

    Science.gov (United States)

    Clemens, M R

    1991-12-15

    During the past decade, remarkable progress has been made in our understanding of cancer-causing agents, mechanisms of cancer formation and the behavior of cancer cells. Cancer is characterized primarily by an increase in the number of abnormal cells derived from a given normal tissue, invasion of adjacent tissues by these abnormal cells, and lymphatic or blood-borne spread of malignant cells to regional lymph nodes and to distant sites (metastasis). It has been estimated that about 75-80% of all human cancers are environmentally induced, 30-40% of them by diet. Only a small minority, possibly no more than 2% of all cases, result purely from inherent genetic changes. Several lines of evidence confirm that the fundamental molecular event or events that cause a cell to become malignant occur at the level of the DNA and a variety of studies indicate that the critical molecular event in chemical carcinogenesis is the interaction of the chemical agent with DNA. The demonstration that DNA isolated from tumor cells can transfect normal cells and render them neoplastic provides direct proof that an alteration of the DNA is responsible for cancer. The transforming genes, or oncogenes, have been identified by restriction endonuclease mapping. One of the characteristics of tumor cells generated by transformation with viruses, chemicals, or radiation is their reduced requirement for serum growth factors. A critical significance of electrophilic metabolites of carcinogenes in chemical carcinogenesis has been demonstrated. A number of "proximate" and "ultimate" metabolites, especially those of aromatic amines, were described. The "ultimate" forms of carcinogens actually interact with cellular constituents to cause neoplastic transformation and are the final metabolic products in most pathways. Recent evidence indicates that free radical derivatives of chemical carcinogens may be produced both metabolically and nonenzymatically during their metabolism. Free radicals carry no

  20. Muonium radicals in benzene-styrene mixtures

    International Nuclear Information System (INIS)

    Ng, B.W.; Stadlbauer, J.W.; Walker, D.C.

    1984-01-01

    Muonium radicals were observed through their μ + SR precession frequencies in high transverse magnetic fields in pure benzene, pure styrene and their mixtures, all as liquids at room temperature. In benzene-styrene mixtures, the radicals obtained in each pure liquid are both present, so no slow (10 -9 -10 -5 s) intermolecular exchange occurs; but strong selectivity was found with the formation of the radical from styrene being about eight-times more probable than the radical from benzene. (Auth.)

  1. Pulse radiolysis of alkanes: a time-resolved EPR study - Part I. Alkyl radicals

    International Nuclear Information System (INIS)

    Shkrob, I.A.; Trifunac, A.D.

    1995-01-01

    Time-resolved EPR was applied to detect short-lived alkyl radicals in pulse radiolysis of liquid alkanes. Two problems were addressed: (i) the mechanism of radical formation and (ii) the mechanism of chemically-induced spin polarization in these radicals. (i) The ratio of yields of penultimate and interior radicals in n-alkanes at the instant of their generation was found to be ≅ 1.25 times greater than the statistical quantity. This higher-than-statistical production of penultimate radicals indicates that the proton transfer reaction involving excited radical cations must be a prevailing route of radical generation. The relative yields of hydrogen abstraction and fragmentation for various branched alkanes are estimated. It is concluded that the fragmentation occurs prior to the formation of radicals in an excited precursor species. (ii) The analysis of spin-echo kinetics in n-alkanes suggests that the alkyl radicals gain the emissive polarization in spur reactions. This initial polarization increases with shortening of the aliphatic chain. We suggest that the origin of this polarization is the ST mechanism operating in the pairs of alkyl radicals and hydrogen atoms generated in dissociation of excited alkane molecules. It is also found that a long-chain structure of alkyl radicals results in much higher rate of Heisenberg spin exchange relative to the recombination rate (up to 30 times). That suggests prominent steric effects in recombination or the occurrence of through-chain electron exchange. The significance of these results in the context of cross-linking in polyethylene and higher paraffins is discussed. (Author)

  2. Free radicals in health and disease

    International Nuclear Information System (INIS)

    Gonet, B.

    1993-01-01

    Free radicals appear in the cells as the result of exogenic factors (ionizing radiation, UV) or reactions naturally occurring in the cell. Free radical reactions may cause destruction of macromolecules (DNA, lipids, proteins). Free radical pathology is important in many diseases and aging processes in organisms

  3. Oxygen free radicals in rheumatoid arthritis

    NARCIS (Netherlands)

    P. Biemond (Pieter)

    1986-01-01

    textabstractCurrent knowledge strongly suggests that oxygen free radicals are involved in the pathogenesis of RA. Additional information about the mechanism of free radical attack is necessary in order to find out if interaction with the mechanism of free radical damage can be used in the treatment

  4. Radical carbonylations using a continuous microflow system

    Directory of Open Access Journals (Sweden)

    Takahide Fukuyama

    2009-07-01

    Full Text Available Radical-based carbonylation reactions of alkyl halides were conducted in a microflow reactor under pressurized carbon monoxide gas. Good to excellent yields of carbonylated products were obtained via radical formylation, carbonylative cyclization and three-component coupling reactions, using tributyltin hydride or TTMSS as a radical mediator.

  5. A muoniated radical in selenium

    International Nuclear Information System (INIS)

    Reid, I.D.; Cox, S.F.J.; Jayasooriya, U.A.; Zimmermann, U.

    2003-01-01

    We report new 0.3 T transverse-field μSR experiments in crystalline Se which show only a small, slowly relaxing muon signal at 300 K, accounting for about 30% of the incoming muon polarization. However, at 90 K signals are observed around 74 and 157 MHz, characteristic of a radical with a hyperfine coupling of 231 MHz. Very fast relaxation which increases with temperature makes these signals impossible to follow beyond 200 K. Above 400 K a quickly relaxing diamagnetic signal becomes visible, its relaxation falling with increasing temperature. In the melt (>490 K) just a single non-relaxing diamagnetic signal is seen. These observations may be explained by electron spin-exchange with a muoniated radical

  6. DNA Binding Hydroxyl Radical Probes

    OpenAIRE

    Tang, Vicky J; Konigsfeld, Katie M; Aguilera, Joe A; Milligan, Jamie R

    2012-01-01

    The hydroxyl radical is the primary mediator of DNA damage by the indirect effect of ionizing radiation. It is a powerful oxidizing agent produced by the radiolysis of water and is responsible for a significant fraction of the DNA damage associated with ionizing radiation. There is therefore an interest in the development of sensitive assays for its detection. The hydroxylation of aromatic groups to produce fluorescent products has been used for this purpose. We have examined four different c...

  7. Anatomical landmarks of radical prostatecomy.

    Science.gov (United States)

    Stolzenburg, Jens-Uwe; Schwalenberg, Thilo; Horn, Lars-Christian; Neuhaus, Jochen; Constantinides, Costantinos; Liatsikos, Evangelos N

    2007-03-01

    In the present study, we review current literature and based on our experience, we present the anatomical landmarks of open and laparoscopic/endoscopic radical prostatectomy. A thorough literature search was performed with the Medline database on the anatomy and the nomenclature of the structures surrounding the prostate gland. The correct handling of puboprostatic ligaments, external urethral sphincter, prostatic fascias and neurovascular bundle is necessary for avoiding malfunction of the urogenital system after radical prostatectomy. When evaluating new prostatectomy techniques, we should always take into account both clinical and final oncological outcomes. The present review adds further knowledge to the existing "postprostatectomy anatomical hazard" debate. It emphasizes upon the role of the puboprostatic ligaments and the course of the external urethral sphincter for urinary continence. When performing an intrafascial nerve sparing prostatectomy most urologists tend to approach as close to the prostatic capsula as possible, even though there is no concurrence regarding the nomenclature of the surrounding fascias and the course of the actual neurovascular bundles. After completion of an intrafascial technique the specimen does not contain any periprostatic tissue and thus the detection of pT3a disease is not feasible. This especially becomes problematic if the tumour reaches the resection margin. Nerve sparing open and laparoscopic radical prostatectomy should aim in maintaining sexual function, recuperating early continence after surgery, without hindering the final oncological outcome to the procedure. Despite the different approaches for radical prostatectomy the key for better results is the understanding of the anatomy of the bladder neck and the urethra.

  8. Radical Smiles Rearrangement: An Update

    Directory of Open Access Journals (Sweden)

    Ingrid Allart-Simon

    2016-07-01

    Full Text Available Over the decades the Smiles rearrangement and its variants have become essential synthetic tools in modern synthetic organic chemistry. In this mini-review we summarized some very recent results of the radical version of these rearrangements. The selected examples illustrate the synthetic power of this approach, especially if it is incorporated into a domino process, for the preparation of polyfunctionalized complex molecules.

  9. Free radical reactions of daunorubicin

    International Nuclear Information System (INIS)

    Houee-Levin, C.

    1991-01-01

    Daunorubicin is an antitumor antibiotic activated in vivo by reduction. Its mechanism of action involves DNA and topoisomerase attack, but side effects are cytotoxicity related to free radical formation. Therefore the mechanism of the one-electron reduction of the drug and the reactions of the daunorubicin transients towards compounds of biological interest have been studied by the methods of radiolysis, in order to provide possible explanations of the drug mechanism of action. Their relative importance in cellular conditions is discussed [fr

  10. Geoscientists and the Radical Middle

    Science.gov (United States)

    Tinker, S. W.

    2015-12-01

    Addressing the great challenges facing society requires industry, government, and academia to work together. I call this overlap space, where compromises are made and real solutions determined, the Radical Middle. Radical because it can appear at times as if the loudest and most publicly influential voices lie outside of the actual solution space, content to provoke but not problem-solve. One key area where geoscientists can play a lead role in the Radical Middle is in the overlap between energy, the environment, and the economy. Globally, fossil fuels still represent 85% of the aggregate energy mix. As existing conventional oil and natural-gas reservoir production continues to slowly decline, unconventional reservoirs, led today by shale and other more expensive resources, will represent a growing part of the oil and gas production mix. Many of these unconventional reservoirs require hydraulic fracturing. The positive economic impact of hydraulic fracturing and associated natural gas and oil production on the United States economy is well documented and undeniable. Yet there are environmental concerns about fracking, and some states and nations have imposed moratoria. This energy-environment-economy space is ideal for leadership from the geosciences. Another such overlap space is the potential for geoscience leadership in relations with China, whose economy and global presence continue to expand. Although China is building major hydropower and natural-gas power plants, as well as nuclear reactors, coal is still king—with the associated environmental impacts. Carbon sequestration—onshore in brine and to enhance oil recovery, as well as offshore—could prove viable. It is vital that educated and objective geoscientists from industry, government, and academia leave their corners and work together in the Radical Middle to educate the public and develop and deliver balanced, economically sensible energy and environmental strategies.

  11. Living PSA

    International Nuclear Information System (INIS)

    Evans, M.G.K.

    1997-01-01

    The aim of this presentation is to gain an understanding of the requirements for a PSA to be considered a Living PSA. The presentation is divided into the following topics: Definition; Planning/Documentation; Task Performance; Maintenance; Management. 4 figs

  12. Poly(2-hydroxyethyl methacrylate) grafted halloysite nanotubes as a molecular host matrix for luminescent ions prepared by surface-initiated RAFT polymerization and coordination chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Md. Rafiqul; Bach, Long Giang; Lim, Kwon Taek, E-mail: ktlim@pknu.ac.kr

    2013-07-01

    A fluorescent nanohybrid complex comprising of halloysite nanotubes (HNTs), poly(2-hydroxyethyl methacrylate) (PHEMA), and europium ions (Eu{sup 3+}) was synthesized by the combination of surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization and coordination chemistry. Initially, PHEMA was grafted from the HNTs by SI-RAFT and then reacted with succinic anhydride to provide carboxyl acid groups on the external layers of HNTs-g-PHEMA nanohybrids. The subsequent coordination of the nanohybrids with Eu{sup 3+} ions afforded photoluminescent Eu{sup 3+} tagged HNTs-g-PHEMA nanohybrid complexes (HNTs-g-PHEMA-Eu{sup 3+}). The structure, morphology, and fluorescence properties of the Eu{sup 3+} coordinated nanohybrid complexes were investigated by respective physical and spectral studies. FT-IR, XPS, and EDS analyses suggested the formation of the HNTs-g-PHEMA-Eu{sup 3+} nanohybrids. FE-SEM images indicated the immobilization of polymer layers on HNTs. TGA scans further demonstrated the grafting of PHEMA onto HNTs surface. The optical properties of HNTs-g-PHEMA-Eu{sup 3+} nanohybrid complexes were investigated by photoluminescence spectroscopy.

  13. Fabrication of an SPR Sensor Surface with Antifouling Properties for Highly Sensitive Detection of 2,4,6-Trinitrotoluene Using Surface-Initiated Atom Transfer Polymerization

    Directory of Open Access Journals (Sweden)

    Kiyoshi Toko

    2013-07-01

    Full Text Available In this study, we modified a surface plasmon resonance immunosensor chip with a polymer using surface-initiated atom transfer polymerization (SI-ATRP for the highly sensitive detection of 2,4,6-trinitrotoluene (TNT. To immobilize a TNT analogue on the polymer, mono-2-(methacryloyloxyethylsuccinate (MES, which has a carboxyl group, was used in this study. However, the anti-TNT antibody may adsorb non-specifically on the polymer surface by an electrostatic interaction because MES is negatively charged. Therefore, a mixed monomer with MES and diethylaminoethylmethacrylate (DEAEM, which has a tertiary amino group and is positively charged, was prepared to obtain electroneutrality for suppressing the nonspecific adsorption. The detection of TNT was performed by inhibition assay using the polymer surface. To ensure high sensitivity to TNT, the affinity between the surface and the antibody was optimized by controlling the density of the initiator for ATRP by mixing two types of self-assembled monolayer reagents. As a result, a limit of detection of 5.7 pg/mL (ppt for TNT was achieved using the optimized surface.

  14. Poly(allyl methacrylate) functionalized hydroxyapatite nanocrystals via the combination of surface-initiated RAFT polymerization and thiol-ene protocol: a potential anticancer drug nanocarrier.

    Science.gov (United States)

    Bach, Long Giang; Islam, Md Rafiqul; Vo, Thanh-Sang; Kim, Se-Kwon; Lim, Kwon Taek

    2013-03-15

    Hydroxyapatite nanocrystals (HAP NCs) were encapsulated by poly(allyl methacrylate) (PolyAMA) employing controlled surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization of allyl methacrylate to afford HAP-PolyAMA nanohybrids. The subsequent thiol-ene coupling of nanohybrids with 2-mercaptosuccinic acid resulted HAP-Poly(AMA-COOH) possessing multicarboxyl group. The formation of the nanohybrids was confirmed by FT-IR and EDS analyses. The TGA and FE-SEM investigation were further suggested the grafting of PolyAMA onto HAP NCs. The utility of the HAP-PolyAMA nanohybrid as drug carrier was also explored. The pendant carboxyl groups on the external layers of nanohybrids were conjugated with anticancer drug cisplatin to afford HAP-Poly(AMA-COOH)/Pt complex. The formation of the complex was confirmed by FT-IR, XPS, and FE-SEM. In vitro evaluation of the synthesized complex as nanomedicine revealed its potential chemotherapeutic efficacy against cancer cell lines. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Surface-initiated ring-opening metathesis polymerization (SI-ROMP) to attach a tethered organic corona onto CdSe/ZnS core/shell quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Vatansever, Fatma, E-mail: vatansever.fatma@mgh.harvard.edu; Hamblin, Michael R., E-mail: hamblin@helix.mgh.harvard.edu [Massachusetts General Hospital, Wellman Center for Photomedicine (United States)

    2016-10-15

    Core–shell CdSe/ZnS quantum dots (QDs) are useful as tunable photostable fluorophores for multiple applications in industry, biology, and medicine. However, to achieve the optimum optical properties, the surface of the QDs must be passivated to remove charged sites that might bind extraneous substances and allow aggregation. Here we describe a method of growing an organic polymer corona onto the QD surface using the bottom-up approach of surface-initiated ring-opening metathesis polymerization (SI-ROMP) with Grubbs catalyst. CdSe/ZnS QDs were first coated with mercaptopropionic acid by displacing the original tri-octylphosphine oxide layer, and then reacted with 7-octenyl dimethyl chlorosilane. The resulting octenyl double bonds allowed the attachment of ruthenium alkylidene groups as a catalyst. A subsequent metathesis reaction with strained bicyclic monomers (norbornene-dicarbonyl chloride (NDC), and a mixture of NDC and norbornenylethylisobutyl-polyhedral oligomeric silsesquioxane (norbornoPOSS)) allowed the construction of tethered organic homo-polymer or co-polymer layers onto the QD. Compounds were characterized by FT-IR, 1H-NMR, X-ray photoelectron spectroscopy, differential scanning calorimetry, and transmission electron microscopy. Atomic force microscopy showed that the coated QDs were separate and non-aggregated with a range of diameter of 48–53 nm.

  16. EPR spin trapping of protein radicals

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan; Hawkins, Clare Louise

    2004-01-01

    Electron paramagnetic resonance (EPR) spin trapping was originally developed to aid the detection of low-molecular-mass radicals formed in chemical systems. It has subsequently found widespread use in biology and medicine for the direct detection of radical species formed during oxidative stress...... tumbling radicals are often broad and relatively poor in distinctive features, a number of techniques have been developed that allow a wealth of information to be obtained about the nature, site, and reactions of such radicals. This article summarizes recent developments in this area and reviews selected...... examples of radical formation on proteins....

  17. Youth De-Radicalization: A Canadian Framework

    Directory of Open Access Journals (Sweden)

    Hafal (Haval Ahmad

    2017-09-01

    Full Text Available Youth radicalization leading to violence has become a growing fear among Canadians, as terrorist attacks are carried out in Western states. Although Canada has suffered relatively fewer acts of violence, this fear has intensified and a de-radicalization strategy is needed in the Canadian context. In a qualitative case study methodology, interviews were conducted with school counsellors, religious leaders, and academics to explore solutions to youth radicalization. Youth de-radicalization approaches from the United Kingdom were analyzed and found that community-based initiatives were missing from programming. Social identity theory is used to explain that youth join radicalized groups to feel a sense of belonging and have to be provided an alternative and moderate group identity to de-radicalize. This study found youth de-radicalization in Canada is best served through a community collaboration approach.

  18. Chemical repair of trypsin-histidinyl radical

    International Nuclear Information System (INIS)

    Jovanovic, S.V.; Ruvarac, I.; Jankovic, I.; Josimovic, L.

    1991-01-01

    Oxyl radicals, such as hydroxyl, alkoxyl and peroxyl, react with biomolecules to produce bioradicals. Unless chemically repaired by suitable antioxidants, these bioradicals form stable products. This leads to loss of biological function of parent biomolecules with deleterious biological results, such as mutagenesis and cancer. Consequently, the understanding of the mechanisms of oxyl radical damage to biomolecules and chemical repair of such damage is crucial for the development of strategies for anticarcinogenesis and radioprotection. In this study the chemical repair of the histidinyl radical generated upon the trichloromethylperoxyl radical reaction with trypsin vas investigated by gamma radiolysis. The trypsin histidinyl radical is a resonance-stabilized heterocyclic free radical which was found to be unreactive with oxygen. The efficacy of the chemical repair of the trypsin-histidinyl radical by endogenous antioxidants which are electron donors (e.g. 5-hydroxytryptophan, uric acid) is compared to that of antioxidants which are H-atom donors (e. g. glutathione). 9 refs., 2 figs., 1 tab

  19. A/r/tographic Collaboration as Radical Relatedness

    Directory of Open Access Journals (Sweden)

    Barbara Bickel PhD

    2011-03-01

    Full Text Available In this paper the authors examine a/r/tographical collaboration in a community-engaged research study investigating immigrant understandings of home and place. The study, The City of Richgate, involves a complex collaboration between community members, community organizations, educational institutions, and a research team comprising artist-educators. The study crosses border zones of cultural, ethnic, geographic, institutional, public, private, and disciplinary boundaries, reflecting the ever-changing character of postmodern reality. In this paper the authors reflect critically and theoretically on the lived experience of radical relatedness found within the complex collaboration, particularly within the a/r/tographic research team. This offers a qualitative methodology of radical collaboration applicable to many fields of inquiry in the academy, art world, and community.

  20. FAR RIGHT RADICALIZATION AND SOCIALIST RADICALIZATION IN INTERWAR ROMANIA

    Directory of Open Access Journals (Sweden)

    IONUŢ BUTOI

    2017-03-01

    Full Text Available In his comments on Mircea Vulcănescu. O microistorie a interbelicului românesc (Eikon, 2015, Emanuel Copilaş states that, regarding the cause of the far right radicalization manifested in the interwar Romania, I share the same historical explanation about fascism as Ernst Nolte. In this concise answer, I explain why this is an unsuitable comparison by summarizing the historiographical perspective I use in the cited volume. Nevertheless, Copilaş’s comments are reopening a debate about how to explain the Romanian fascism

  1. Radical probing of spliceosome assembly.

    Science.gov (United States)

    Grewal, Charnpal S; Kent, Oliver A; MacMillan, Andrew M

    2017-08-01

    Here we describe the synthesis and use of a directed hydroxyl radical probe, tethered to a pre-mRNA substrate, to map the structure of this substrate during the spliceosome assembly process. These studies indicate an early organization and proximation of conserved pre-mRNA sequences during spliceosome assembly. This methodology may be adapted to the synthesis of a wide variety of modified RNAs for use as probes of RNA structure and RNA-protein interaction. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Iron and iron derived radicals

    International Nuclear Information System (INIS)

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fast! Think small! In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab

  3. Remembering Dutch-Moluccan radicalism

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2016-01-01

    This article examines memory politics in relation to radical actions of young Dutch-Moluccans, more specifically a train hijacking in 1977 at the village of De Punt in the Netherlands. The article examines how these historical events were remembered in the drama-documentary television film, De Punt...... of the web debate examines how viewers reacted to this interpretation. The web debate functioned as a participatory forum, where collective and national memories and postcolonial history were intensely discussed, and the debate made room for some degree of reconciliation between viewers of Dutch......-Moluccan and of Dutch majority background...

  4. Laser spectroscopy of hydrocarbon radicals

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P. [Harvard Univ., Cambridge, MA (United States)

    1993-12-01

    The author reports the application of supersonic jet flash pyrolysis to the specific preparation of a range of organic radicals, biradicals, and carbenes in a skimmed molecular beam. Each species was produced cleanly and specifically, with little or no secondary reactions by the thermal dissociation of appropriately designed and synthesized organic precursors. Photoelectron spectra of the three isomeric C{sub 3}H{sub 2} carbenes, ortho-benzyne, and the {alpha},3-dehydrotoluene biradical, were used to establish adiabatic ionization potentials for use in thermochemical determinations.

  5. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

    1993-12-01

    The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

  6. Radical constructivism: Between realism and solipsism

    Science.gov (United States)

    Martínez-Delgado, Alberto

    2002-11-01

    This paper criticizes radical constructivism of the Glasersfeld type, pointing out some contradictions between the declared radical principles and their theoretical and practical development. These contradictions manifest themselves in a frequent oscillation between solipsism and realism, despite constructivist claims to be an anti-realist theory. The paper also points out the contradiction between the relativism of the radical constructivist principles and the constructivist exclusion of other epistemological or educational paradigms. It also disputes the originality and importance of the radical constructivist paradigm, suggesting the idea of an isomorphism between radical constructivist theory and contemplative realism. In addition, some pedagogical and scientific methodological aspects of the radical constructivist model are examined. Although radical constructivism claims to be a rational theory and advocates deductive thinking, it is argued that there is no logical deductive connection between the radical principles of constructivism and the radical constructivist ideas about scientific research and learning. The paper suggests the possibility of an ideological substratum in the construction and hegemonic success of subjective constructivism and, finally, briefly advances an alternative realist model to epistemological and educational radical constructivism.

  7. Assisted Living

    Science.gov (United States)

    ... a resident's needs depends as much on the philosophy and services of the assisted living facility as it does on the quality of care. The Administration on Aging, a part of the U.S. Department of Health and Human Services (HHS), offers these suggestions to help you ...

  8. Easier living?

    DEFF Research Database (Denmark)

    Høholt, Stine

    2005-01-01

    I ph.d.-projektet: "Easier Living? Streamline design og den æstetiserede livsverden" analyseres 1930'ernes Streamline-bevægelse, som tilhører den amerikanske modernisme inden for industrielt produktdesign. Bevægelsens glatte, strømlinede produkter bliver med deres enorme udbredelse det historiske...

  9. Free Radical Imaging Using In Vivo Dynamic Nuclear Polarization-MRI.

    Science.gov (United States)

    Utsumi, Hideo; Hyodo, Fuminori

    2015-01-01

    Redox reactions that generate free radical intermediates are essential to metabolic processes, and their intermediates can produce reactive oxygen species, which may promote diseases related to oxidative stress. The development of an in vivo electron spin resonance (ESR) spectrometer and its imaging enables us noninvasive and direct measurement of in vivo free radical reactions in living organisms. The dynamic nuclear polarization magnetic resonance imaging (DNP-MRI), also called PEDRI or OMRI, is also a new imaging method for observing free radical species in vivo. The spatiotemporal resolution of free radical imaging with DNP-MRI is comparable with that in MRI, and each of the radical species can be distinguished in the spectroscopic images by changing the frequency or magnetic field of ESR irradiation. Several kinds of stable nitroxyl radicals were used as spin probes to detect in vivo redox reactions. The signal decay of nitroxyl probes, which is determined with in vivo DNP-MRI, reflects the redox status under oxidative stress, and the signal decay is suppressed by prior administration of antioxidants. In addition, DNP-MRI can also visualize various intermediate free radicals from the intrinsic redox molecules. This noninvasive method, in vivo DNP-MRI, could become a useful tool for investigating the mechanism of oxidative injuries in animal disease models and the in vivo effects of antioxidant drugs. © 2015 Elsevier Inc. All rights reserved.

  10. Intramolecular transformation of thiyl radicals to α-aminoalkyl radicals: 'ab initio' calculations on homocystein

    International Nuclear Information System (INIS)

    Chhun, S.; Berges, J.; Bleton, V.; Abedinzadeh, Z.

    2000-01-01

    One-electron oxidation of thiols by oxidizing radicals leads to the formation of thiyl radical and carbon-centered radicals. It has been shown experimentally that in the absence of oxygen, the thiyl radicals derived from certain thiols of biological interest such as glutathion, cysteine and homocysteine decay rapidly by intramolecular rearrangement reactions into the carbon-centered radical. In the present work we have investigated theoretically the structure and the stability of thiyl and carbon-centered radicals of homocysteine in order to check the possibility of this rearrangement. (author)

  11. Radiation-initiated free-radical fragmentation of biologically active glycerides

    International Nuclear Information System (INIS)

    Akhrem, A.A.; Kisel', M.A.; Shadyro, O.I.; Yurkova, I.L.

    1993-01-01

    Oxidation reactions of the free-radical type play a decisive role in the initial processes of radiation damage. The most suitable substrates for such reactions are lipids. Lipids are a basic structural element of biomembranes and are involved in the barrier function and biocatalytic activity of such membranes. Free-radical degradation of membrane lipids can lead to serious damage and ultimately to destruction of the living cell. A well-studied type of free-radical conversion of lipids is oxidation of polyunsaturated fatty acid residues, so-called peroxide oxidation of lipids. In this paper, using as examples dimyristoylphosphatidyl glycerol (DMPG), monoglycerides, and glycerophosphate, the authors investigated the possibility of free-radical degradation in compounds of a lipid nature containing the α,β-bifunctional group

  12. Radicalization In Pakistan And The Spread Of Radical Islam In Pakistan

    Directory of Open Access Journals (Sweden)

    Bahir ahmad

    2015-08-01

    Full Text Available ABSTRACT It is pertinent to mention that radicalism is not intrinsic to Islam and radical interpretations of the religion or for that matter may occur within any way of life and religion Saikal 2003 and yet the question remains as to why Muslims in certain geographical regions have more radical approaches towards their religion and also that what are the causes of such radicalization. Becoming a radical Muslim is not even a matter of a day nor is it a sudden process. There are several reasons behind making a person radical peaceful angry smiling or tolerant. For knowing the reason behind radicalization or radicals persons one has to understand the causes. Tracing these causes is one of the ways to eliminate such behavior. The first step in the elimination of the radical sentiments in a person is to develop peace in his personality Fair Malhotra amp Shapiro 2010. The chapter which has been addressed here is going to shed light on the roots and symptoms of the radicalism. There will be a brief discussion on how the roots of radicalism can be traced and can be eliminated. The assessment and discussion will be conducted on the parameters of the economy media politics and theology from social cultural point of view. According to the analysis of Ahrari 2000 political factor is one of the major and direct factors which have resulted in causing of the radicalism. These factors however intertwine with one another. Radical actions cannot take place only because of the political factors.

  13. Fluorescence lifetime measurement of radical ions

    International Nuclear Information System (INIS)

    Ichinose, Nobuyuki; Kinugasa, Jun-ichiro; Hagiri, Masahide; Nakayama, Toshihiro; Murakami, Hiroshi; Kishimoto, Maki; Daido, Hiroyuki

    2004-01-01

    One-photonic excitation of a charge transfer complex of hexamethoxybenzene (HMB) and nitrosonium tetrafluoroborate (NO + BF 4 - ) in acetonitrile afforded fluorescences emission from excited radical cation of HMB (HMB + *). Lifetime of the excited radical ion species was measured to be 7 ps by the pump-probe transient absorption technique. The lifetime was much shorter than that of free radical ion (63 ps), indicating the presence of an interaction between HMB + * and NO in the excited complex. (author)

  14. Reorientation dynamics of cyclohexadienyl radicals in zeolites

    International Nuclear Information System (INIS)

    Stolmar, M.; Roduner, E.; Dilger, H.; Himmer, U.; Shelley, M.; Reid, I.D.

    1997-01-01

    The dynamics of the muonium substituted cyclohexadienyl radical adsorbed on silicalite and NaZSM-5 is investigated by means of avoided level crossing muon spin resonance. The influence of benzene loading on the mobility of the radical is studied. At low loadings the radicals were found to be located on a single adsorption site where they undergo a wobbling type of motion. With increasing loading an additional species adsorbed on a different site is observed

  15. The Rise of Radicals in Bioinorganic Chemistry

    OpenAIRE

    Gray, Harry B.; Winkler, Jay R.

    2016-01-01

    Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O_2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) a...

  16. Austrian Lives

    OpenAIRE

    Bischof, Günter; Plasser, Fritz; Maltschnig, Eva

    2012-01-01

    Writing biographies for a long time had been a male hegemonic project. Ever since Plutarch and Sueton composed their vitae of the greats of classical antiquity, to the medieval obsession with the hagiographies of holy men (and a few women) and saints, Vasari's lives of great Renaissance artists, down to the French encyclopedists, Dr. Johnson and Lytton Strachey, as well as Ranke and Droysen the genre of biographical writing has become increasingly more refined. In the twentieth century male p...

  17. Resonance Raman Spectra of the Transient Cl2 and Br2 Radical Anions

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, Niels-Henrik; Sillesen, Alfred Hegaard

    1984-01-01

    The resonance Raman spectra of the short-lived radical anions ClImage 2− and BrImage − in aqueous solution are reported. The observed wavenumbers of 279 cm−1 for ClImage − and 177 cm−1 for BrImage − are about 10% higher than those published for the corresponding species isolated in solid argon ma...

  18. The LEGO toolbox: Supramolecular building blocks by nitroxide-mediated controlled radical polymerization

    NARCIS (Netherlands)

    Lohmeijer, B.G.G.; Schubert, U.S.

    2005-01-01

    A terpyridine-functionalized alkoxyamine unimolecular initiator was used for the nitroxide-mediated controlled living radical polymerization of n-butylacrylate, N,N-dimethylacrylamide, 4-vinylpyridine, 2-vinylpyridine, and isoprene. For the former three monomers, the kinetics were studied. All

  19. Students' Ideas and Radical Constructivism

    Science.gov (United States)

    Sánchez Gómez, Pedro J.

    2016-08-01

    In this article, I study, from the point of view of the analytic philosophy of mind, the compatibility of students' ideas studies (SIS) with radical constructivism (RC). I demonstrate that RC is based on a psychology of narrow mental states; that is, the idea that the mental content of an individual can be fully characterised without any reference external to her or him. I show that this fact imposes some severe restrictions to SIS to be incorporated into RC. In particular, I argue that only qualitative studies can comply with the requirement of narrowness. Nevertheless, I propose that quantitative works can be employed as sources of types in order to study token actual students. I use this type-token dichotomy to put forward an outline of a theory of the relation between school contents and mental contents. In this view, token mental contents regarding a given topic can be defined, and probed, only by resorting to typical school contents.

  20. DNA Binding Hydroxyl Radical Probes.

    Science.gov (United States)

    Tang, Vicky J; Konigsfeld, Katie M; Aguilera, Joe A; Milligan, Jamie R

    2012-01-01

    The hydroxyl radical is the primary mediator of DNA damage by the indirect effect of ionizing radiation. It is a powerful oxidizing agent produced by the radiolysis of water and is responsible for a significant fraction of the DNA damage associated with ionizing radiation. There is therefore an interest in the development of sensitive assays for its detection. The hydroxylation of aromatic groups to produce fluorescent products has been used for this purpose. We have examined four different chromophores which produce fluorescent products when hydroxylated. Of these, the coumarin system suffers from the fewest disadvantages. We have therefore examined its behavior when linked to a cationic peptide ligand designed to bind strongly to DNA.

  1. Photoionisation of the tropyl radical

    Directory of Open Access Journals (Sweden)

    Kathrin H. Fischer

    2013-04-01

    Full Text Available We present a study on the photoionisation of the cycloheptatrienyl (tropyl radical, C7H7, using tunable vacuum ultraviolet synchrotron radiation. Tropyl is generated by flash pyrolysis from bitropyl. Ions and electrons are detected in coincidence, permitting us to record mass-selected photoelectron spectra. The threshold photoelectron spectrum of tropyl, corresponding to the X+ 1A1’ ← X 2E2” transition, reveals an ionisation energy of 6.23 ± 0.02 eV, in good agreement with Rydberg extrapolations, but slightly lower than the value derived from earlier photoelectron spectra. Several vibrations can be resolved and are reassigned to the C–C stretch mode ν16+ and to a combination of ν16+ with the ring breathing mode ν2+. Above 10.55 eV dissociative photoionisation of tropyl is observed, leading to the formation of C5H5+ and C2H2.

  2. CRITICAL THEORY OF THE RADICAL LOVE TEORÍA CRÍTICA DEL RADICAL LOVE

    Directory of Open Access Journals (Sweden)

    Lena de Botton

    2009-11-01

    Full Text Available The understanding of the sexual-affective relationships has historically notbeen tackled by science, but placed in the context of instincts and irrationality. In thissense, the critical theory of the Radical Love provides a contribution to critical pedagogyallowing people to understand the mechanisms that direct their emotions and theprocess of election in the sexual-affective relationships. It is about understanding whodo we fall in love for, why and to which values is this desire linked being able to have agreat repercussion in our lives as it provides us with the tools to develop satisfactorysexual-affective relationships. It also offers us guidelines for a preventive educationregarding gender violence by enabling us to understand the attraction models in whichwe have been socialised and which are influencing our desire and elections.Históricamente la comprensión de las relaciones sexual-afectivas no ha sidoabordada desde la ciencia, sino que ha sido situada en el marco de los instintos y de lairracionalidad. En este sentido, la teoría crítica del Radical Love realiza una contribuciónpara la pedagogía crítica al permitir a las personas comprender los mecanismos querigen en las emociones y en el proceso de elección de las relaciones sexual-afectivas. Setrata de comprender de quiénes nos enamoramos, por qué y a qué valores se entrelazaeste deseo, puesto que todo ello puede tener una gran repercusión en nuestras vidas.Avanzar hacia esta comprensión nos da las herramientas para poder desarrollar unasrelaciones afectivo-sexuales satisfactorias. También nos ofrece orientaciones para unaeducación preventiva de la violencia de género al permitirnos comprender los modelosde atracción en los que nos hemos socializado y que influyen en nuestro deseo y elección.

  3. Free radical generation from an aniline derivative in HepG2 cells: a possible captodative effect.

    Science.gov (United States)

    Horinouchi, Yuya; Summers, Fiona A; Ehrenshaft, Marilyn; Mason, Ronald P

    2015-01-01

    Xenobiotic metabolism can induce the generation of protein radicals, which are believed to play an important role in the toxicity of chemicals and drugs. It is therefore important to identify chemical structures capable of inducing macromolecular free radical formation in living cells. In this study, we evaluated the ability of four structurally related environmental chemicals, aniline, nitrosobenzene, N,N-dimethylaniline, and N,N-dimethyl-4-nitrosoaniline (DMNA), to induce free radicals and cellular damage in the hepatoma cell line HepG2. Cytotoxicity was assessed using lactate dehydrogenase assays, and morphological changes were observed using phase contrast microscopy. Protein free radicals were detected by immuno-spin trapping using in-cell western experiments and confocal microscopy to determine the subcellular locale of free radical generation. DMNA induced free radical generation, lactate dehydrogenase release, and morphological changes in HepG2 cells, whereas aniline, nitrosobenzene, N,N-dimethylaniline did not. Confocal microscopy showed that DMNA induced free radical generation mainly in the cytosol. Preincubation of HepG2 cells with N-acetylcysteine and 2,2'-dipyridyl significantly prevented free radical generation on subsequent incubation with DMNA, whereas preincubation with apocynin and dimethyl sulfoxide had no effect. These results suggest that DMNA is metabolized to reactive free radicals capable of generating protein radicals which may play a critical role in DMNA toxicity. We propose that the captodative effect, the combined action of the electron-releasing dimethylamine substituent, and the electron-withdrawing nitroso substituent, leads to a thermodynamically stabilized radical, facilitating enhanced protein radical formation by DMNA. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Living Lands

    DEFF Research Database (Denmark)

    Christensen, Suna Møller

    2015-01-01

    , hunters attended to questions like safe-journeying on ice or the role of natural surroundings in children’s education, in ways revealing a relational perception of ‘nature’ and dissolving culture-nature dualisms. Hunters’ experiences in living the land afforded children a dwelling position from which...... to grow with the features of the land. Framed this way, ‘nature’ was regarded as part of the social world. I suggest that learning among Arctic hunters is social and twofold. First, we can learn how human-environment relations influence individual life trajectories. Secondly, ‘nature’ as part...

  5. Lively package

    International Nuclear Information System (INIS)

    Jaremko, G.

    1997-01-01

    Progress on the Lloydminster Heavy Oil Interpretive Centre, sponsored by the Lloydminster Oilfield Technical Society and expected to open in late 1998, was discussed. Some $150,000 of the $750,000 budget is already in the bank, and another $150,000 is in the pipeline. The Centre will be added to an existing and well-established visitor's site. It is reported to contain a lively and imaginatively-designed exhibit package, and promises to become a combination of educational tool and tourist attraction for the town of Lloydminster, Saskatchewan, in the heart of heavy oil country

  6. Free radicals in biology. Volume II

    International Nuclear Information System (INIS)

    Pryor, W.A.

    1976-01-01

    This volume continues the treatment of topics in free radical biology and free radical pathology from Volume I. In the first chapter, pyridinyl radicals, radicals which are models for those derived from NAD, are discussed. Pyridinyl radicals can be synthesized and isolated and directly studied in a number of chemical systems. The next chapter treats the role of glutathione in the cell. It is becoming even more apparent that this vital thiol controls a large number of important cellular functions. The GSH/GSSG balance has recently been implicated as a control for cellular development; this balance also may be important in relaying the effects of oxidants from one site to another in the body. The next chapter outlines the reactions of singlet oxygen; some of these involve free radicals and some do not. This reactive intermediate appears to be important both in photochemical smog and in cellular chemistry where singlet oxygen is produced by nonphotochemical processes. The production of free radicals from dry tissues, a controversial area with conflicting claims is reviewed. The next chapter outlines the current status of the studies of photochemical smog. The next two chapters treat specific reactive materials which are present in smog. The first discusses the chemistry of nitrogen oxides and ozone. The second chapter treats the chemistry of the peroxyacyl nitrites. These compounds, although present in only small concentration, are among the most toxic components of smog. The last two chapters treat radiation damage to proteins and radiation protection and radical reactions produced by radiation in nucleic acids

  7. Measuring Atmospheric Free Radicals Using Chemical Amplification

    Science.gov (United States)

    1988-05-01

    CH 3Br, H2S, and SO2 [Logan et al., 1981]. Recently, the OH radical has been determined as the dominant loss mechanism for isoprene and monoterpenes ...W. Heaps, D. Philen, and T. McGee, Bondary Layer Measurements of the OH Radical in the Vicinity of an Isolated Power Plant Plume: SO2 and NO2

  8. Allylthioketone Mediated Free Radical Polymerization of Methacrylates

    Directory of Open Access Journals (Sweden)

    Feng Zhong

    2017-11-01

    Full Text Available By combination of high trapping free radical efficiency of the thioketone and resonance of the allylic radical, a new type of mediating agent, 1,3,3-triphenylprop-2-ene-1-thione (TPPT has been successfully synthesized, and then is used to study controlled free radical polymerization of methacrylates. Very stable TPPT radicals at the end of poly(methyl methacrylate (PMMA are detected in the polymerization of MMA using TPPT and AIBN as the control agent and initiator. The MALDI-TOF MS spectra are used to identify terminal groups of the resultant poly(glycidyl methacrylate (PGMA, and major component of the obtained polymer has the structure, (CH32(CNC-PGMA-C7H9O3. Chain extension reaction tests ascertain formation of the dead polymers during the polymer storage and purification process of the polymers. Owing to very slow fragmentation reaction of the TPPT-terminated polymethacrylate radical and addition reaction of this radical with a primary radical, the growing chain radicals are difficult to be regenerated, leading to an unobvious change of the molecular weight with monomer conversion. The molecular weights of polymers can be controlled by the ratios of monomer/initiator and TPPT/initiator. However, the first order kinetics of the polymerization and the polymers with narrow polydispersity are obtained, and these phenomena are discussed. This study provides useful information on how to design a better controlling agent.

  9. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    B. Mourrain; J.B. Lasserre; M. Laurent (Monique); P. Rostalski; P. Trebuchet (Philippe)

    2013-01-01

    htmlabstractIn this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and

  10. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    Lasserre, J.B.; Laurent, M.; Mourrain, B.; Rostalski, P.; Trébuchet, P.

    2013-01-01

    In this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming its complex (resp. real) variety is finite. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and semi-definite

  11. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    B. Mourrain; J.B. Lasserre; M. Laurent (Monique); P. Rostalski; P. Trebuchet (Philippe)

    2011-01-01

    htmlabstractIn this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and

  12. Quantification of hydroxyl radical produced during phacoemulsification.

    Science.gov (United States)

    Gardner, Jonathan M; Aust, Steven D

    2009-12-01

    To quantitate hydroxyl radicals produced during phacoemulsification with various irrigating solutions and conditions used in cataract surgery. Chemistry and Biochemistry Department, Utah State University, Logan, Utah, USA. All experiments were performed using an Infiniti Vision System phacoemulsifier with irrigation and aspiration. Hydroxyl radicals were quantitated using electron spin resonance spectroscopy and a spectrophotometric assay for malondialdehyde, which is formed by the oxidation of deoxyribose by the hydroxyl radical. Hydroxyl radical production increased during longitudinal-stroking phacoemulsification as power levels were increased in a nonlinear, nonexponential fashion. The detection of hydroxyl radical was reduced in irrigating solutions containing organic molecules (eg, citrate, acetate, glutathione, dextrose) and further reduced in Navstel, an irrigating solution containing a viscosity-modifying agent, hydroxypropyl methylcellulose. Hydroxyl radicals produced in settings representative of those used in phacoemulsification cataract surgery were quantitated using the deoxyribose method. Hydroxyl radical production was dependent on the level of ultrasound power applied and the irrigating solution used. Oxidative stress on the eye during phacoemulsification may be minimized by using irrigating solutions that contain organic molecules, including the viscosity-modifying agent hydroxypropyl methylcellulose, that can compete for reaction with hydroxyl radicals.

  13. Self-Terminating, Oxidative Radical Cyclizations

    Directory of Open Access Journals (Sweden)

    Uta Wille

    2004-05-01

    Full Text Available The recently discovered novel concept of self-terminating, oxidative radical cyclizations, through which alkynes can be converted into carbonyl compounds under very mild reaction conditions using O-centered inorganic and organic radicals as oxidants, is described

  14. Radical Behaviorism and Buddhism: Complementarities and Conflicts

    Science.gov (United States)

    Diller, James W.; Lattal, Kennon A.

    2008-01-01

    Comparisons have been made between Buddhism and the philosophy of science in general, but there have been only a few attempts to draw comparisons directly with the philosophy of radical behaviorism. The present review therefore considers heretofore unconsidered points of comparison between Buddhism and radical behaviorism in terms of their…

  15. Facile surface glycosylation of PVDF microporous membrane via direct surface-initiated AGET ATRP and improvement of antifouling property and biocompatibility

    International Nuclear Information System (INIS)

    Yuan Jing; Meng Jianqiang; Kang Yinlin; Du Qiyun; Zhang Yufeng

    2012-01-01

    This paper describes a facile and novel approach for the surface glycosylation of poly(vinylidene difluoride) (PVDF) microporous membrane. A glycopolymer poly(D-gluconamidoethyl methacrylate) (PGAMA) was tethered onto the membrane surface via activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) directly initiated from the PVDF surface. Chemical changes of membrane surface were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It was revealed that PGAMA was successfully grafted onto the membrane surface and its grafting density can be modulated in a wide range up to 2.4 μmol/cm 2 . The effects of glycosylation on membrane morphology, flux and surface hydrophilicity were investigated. Field emission scanning electron microscopy (FESEM) results indicated shrinkage of the surface pore diameters and the growth of the glycopolymer layer on the membrane surface. The static water contact angle (WCA) of the membrane surface decreased from 110° to 30.4° with the increase of grafting density, indicating that the PGAMA grafts dramatically improved the surface hydrophilicity. The protein adsorption and platelets adhesion experiments indicated that the grafted PGAMA could effectively improve the membrane antifouling property and biocompatibility.

  16. Hydroxyl-radical-induced oxidation of cyclic dipeptides: Reactions of free peptide radicals and their peroxyl radicals

    International Nuclear Information System (INIS)

    Mieden, O.J.

    1989-01-01

    In the course of this study investigations were carried out into the reactions of hydroxyl radicals and hydrogen atoms with cyclic dipeptides as well as the subsequent reactions of peptide radicals and their peroxyl radicals in aqueous solution. The radiolysis products formed in the absence and presence of oxygen or transient metal complexes were characterized and determined on a quantitative basis. The linking of information from product analyses to the kinetic data for transient species obtained by time-resolving UV/VIS and conductivity measurements (pulse radiolysis) as well as computer-assisted simulations of individual events during the reaction permitted an evaluation of the mechanisms underlying the various processes and an identification of interim products with short life-times, which did or did not belong to the group of radicals. Through the characterization of key reactions of radicals and peroxyl radicals of this substance class a major advance has been made towards a better understanding of the role of radicals in the peptide compound and the mechanisms involved in indirect radiation effects on long-chain peptides and proteins. (orig.) [de

  17. Functionalised Oximes: Emergent Precursors for Carbon-, Nitrogen- and Oxygen-Centred Radicals

    Directory of Open Access Journals (Sweden)

    John C. Walton

    2016-01-01

    Full Text Available Oxime derivatives are easily made, are non-hazardous and have long shelf lives. They contain weak N–O bonds that undergo homolytic scission, on appropriate thermal or photochemical stimulus, to initially release a pair of N- and O-centred radicals. This article reviews the use of these precursors for studying the structures, reactions and kinetics of the released radicals. Two classes have been exploited for radical generation; one comprises carbonyl oximes, principally oxime esters and amides, and the second comprises oxime ethers. Both classes release an iminyl radical together with an equal amount of a second oxygen-centred radical. The O-centred radicals derived from carbonyl oximes decarboxylate giving access to a variety of carbon-centred and nitrogen-centred species. Methods developed for homolytically dissociating the oxime derivatives include UV irradiation, conventional thermal and microwave heating. Photoredox catalytic methods succeed well with specially functionalised oximes and this aspect is also reviewed. Attention is also drawn to the key contributions made by EPR spectroscopy, aided by DFT computations, in elucidating the structures and dynamics of the transient intermediates.

  18. Orgasmic Dysfunction after Radical Prostatectomy

    Directory of Open Access Journals (Sweden)

    Paolo Capogrosso

    2017-04-01

    Full Text Available In addition to urinary incontinence and erectile dysfunction, several other impairments of sexual function potentially occurring after radical prostatectomy (RP have been described; as a whole, these less frequently assessed disorders are referred to as neglected side effects. In particular, orgasmic dysfunctions (ODs have been reported in a non-negligible number of cases, with detrimental impacts on patients’ overall sexual life. This review aimed to comprehensively discuss the prevalence and physiopathology of post-RP ODs, as well as potential treatment options. Orgasm-associated incontinence (climacturia has been reported to occur in between 20% and 93% of patients after RP. Similarly, up to 19% of patients complain of postoperative orgasm-associated pain, mainly referred pain at the level of the penis. Moreover, impairment in the sensation of orgasm or even complete anorgasmia has been reported in 33% to 77% of patients after surgery. Clinical and surgical factors including age, the use of a nerve-sparing technique, and robotic surgery have been variably associated with the risk of ODs after RP, although robust and reliable data allowing for a proper estimation of the risk of postoperative orgasmic function impairment are still lacking. Likewise, little evidence regarding the management of postoperative ODs is currently available. In general, physicians should be aware of the prevalence of ODs after RP, in order to properly counsel all patients both preoperatively and immediately post-RP about the potential occurrence of bothersome and distressful changes in their overall sexual function.

  19. Orgasmic Dysfunction after Radical Prostatectomy

    Science.gov (United States)

    Ventimiglia, Eugenio; Cazzaniga, Walter; Montorsi, Francesco; Salonia, Andrea

    2017-01-01

    In addition to urinary incontinence and erectile dysfunction, several other impairments of sexual function potentially occurring after radical prostatectomy (RP) have been described; as a whole, these less frequently assessed disorders are referred to as neglected side effects. In particular, orgasmic dysfunctions (ODs) have been reported in a non-negligible number of cases, with detrimental impacts on patients' overall sexual life. This review aimed to comprehensively discuss the prevalence and physiopathology of post-RP ODs, as well as potential treatment options. Orgasm-associated incontinence (climacturia) has been reported to occur in between 20% and 93% of patients after RP. Similarly, up to 19% of patients complain of postoperative orgasm-associated pain, mainly referred pain at the level of the penis. Moreover, impairment in the sensation of orgasm or even complete anorgasmia has been reported in 33% to 77% of patients after surgery. Clinical and surgical factors including age, the use of a nerve-sparing technique, and robotic surgery have been variably associated with the risk of ODs after RP, although robust and reliable data allowing for a proper estimation of the risk of postoperative orgasmic function impairment are still lacking. Likewise, little evidence regarding the management of postoperative ODs is currently available. In general, physicians should be aware of the prevalence of ODs after RP, in order to properly counsel all patients both preoperatively and immediately post-RP about the potential occurrence of bothersome and distressful changes in their overall sexual function. PMID:28459142

  20. ORGASMIC FUNCTION AFTER RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    D. Yu. Pushkar

    2014-07-01

    Full Text Available Objective: to study orgasmic function (OF in patients undergoing radical prostatectomy (RPE.Subjects and methods. Seventy-nine patients who had undergone RPE for locally advanced prostate cancer without hormone and radiation therapies were examined. The patients’ mean age was 59.3 years. The mean EF-IIEF domain score was 24.4. OF was estimated by IIEF question 10 and the authors’ questionnaire. The Spearman rank correction coefficient and Mann-Whitney U-Wilcoxon tests were used.Results. After RPE, there was a reduction in the mean IIEF question 10 score from 3.9 (confidence interval 3.7–4.1 to 3.3 (3–3.5 (p = 0.000. The following changes were found in orgasm intensity: no changes in 43 %, mild worsening in 42 %, severe worsening in 8 %, and enhancement in 4 %; orgasm could not be achieved in 4 % of the patients. Pain usually of low intensity was reported by 8.8 %. The poor factors for preserving OF were its low baseline level, elderly age, or severe post-RPE erectile dysfunction.Conclusion. There were significant OF changes after RPE, which should be kept in mind while treating this category of patients.

  1. Theoretical investigation of radical species formed from L-α-alanine under gamma-irradiation

    International Nuclear Information System (INIS)

    Simion, C.

    2008-01-01

    Gamma-irradiated L-α-alanine used in EPR-coupled dosimetry has a complex EPR spectrum at room temperature. Changing the temperature or other conditions of the irradiated samples leads to varied EPR spectrum, i.e., some components disappear and/or new ones are formed. We used both molecular mechanics (MM+) and semiempirical (AM1) methods to perform a theoretical investigation of the seven radical species that have been experimentally detected. We established their order of priority in the given simulation conditions (at 0 K, in vacuo). The formation stages advanced for these long-lived radical species were characterized by a theoretical determination of the reaction enthalpies. (author)

  2. User involvement competence for radical innovation

    DEFF Research Database (Denmark)

    Lettl, Christopher

    2007-01-01

    -assisted navigation systems. The case study analysis reveals that firms who closely interact with specific users benefit significantly for their radical innovation work. These users have a high motivation toward new solutions, are open to new technologies, possess diverse competencies, and are embedded into a very......One important market related capability for firms which seek to develop radical innovations is the competence to involve the 'right' users at the 'right' time in the 'right' form. While former studies have identified a rather passive role of users in the radical innovation process, this paper...

  3. User involvement competence for radical innovation

    DEFF Research Database (Denmark)

    Lettl, Christopher

    2007-01-01

    One important market related capability for firms which seek to develop radical innovations is the competence to involve the 'right' users at the 'right' time in the 'right' form. While former studies have identified a rather passive role of users in the radical innovation process, this paper......-assisted navigation systems. The case study analysis reveals that firms who closely interact with specific users benefit significantly for their radical innovation work. These users have a high motivation toward new solutions, are open to new technologies, possess diverse competencies, and are embedded into a very...

  4. Engineering a horseradish peroxidase C stable to radical attacks by mutating multiple radical coupling sites.

    Science.gov (United States)

    Kim, Su Jin; Joo, Jeong Chan; Song, Bong Keun; Yoo, Young Je; Kim, Yong Hwan

    2015-04-01

    Peroxidases have great potential as industrial biocatalysts. In particular, the oxidative polymerization of phenolic compounds catalyzed by peroxidases has been extensively examined because of the advantage of this method over other conventional chemical methods. However, the industrial application of peroxidases is often limited because of their rapid inactivation by phenoxyl radicals during oxidative polymerization. In this work, we report a novel protein engineering approach to improve the radical stability of horseradish peroxidase isozyme C (HRPC). Phenylalanine residues that are vulnerable to modification by the phenoxyl radicals were identified using mass spectrometry analysis. UV-Vis and CD spectra showed that radical coupling did not change the secondary structure or the active site of HRPC. Four phenylalanine (Phe) residues (F68, F142, F143, and F179) were each mutated to alanine residues to generate single mutants to examine the role of these sites in radical coupling. Despite marginal improvement of radical stability, each single mutant still exhibited rapid radical inactivation. To further reduce inactivation by radical coupling, the four substitution mutations were combined in F68A/F142A/F143A/F179A. This mutant demonstrated dramatic enhancement of radical stability by retaining 41% of its initial activity compared to the wild-type, which was completely inactivated. Structure and sequence alignment revealed that radical-vulnerable Phe residues of HPRC are conserved in homologous peroxidases, which showed the same rapid inactivation tendency as HRPC. Based on our site-directed mutagenesis and biochemical characterization, we have shown that engineering radical-vulnerable residues to eliminate multiple radical coupling can be a good strategy to improve the stability of peroxidases against radical attack. © 2014 Wiley Periodicals, Inc.

  5. Some reactions of oxidizing radicals with enzymes in aqueous solution

    International Nuclear Information System (INIS)

    Cundall, R.B.; Bisby, R.H.; Hoe, S.T.; Sims, H.E.; Anderson, R.F.

    1979-01-01

    A range of oxidizing radicals including some inorganic radical anions and the superoxide radical, can be generated by radiolysis of aqueous solutions. These radicals are more selective in their reactions with amino acids than the hydroxyl radical. Factors controlling the apparent reactivity of radical anions with proteins, such as free radical equilibria and ion-binding, are described. The superoxide radical inactivates papain by reaction with the cysteine residue. This reaction has been studied in solutions subjected to radiations of varying linear energy transfer. (Auth.)

  6. Radioprotective effects of dimethyl sulfoxide in golden hamster embryo cells exposed to gamma rays at 77 K. I. Radical formation as studied by electron spin resonance

    International Nuclear Information System (INIS)

    Miyazaki, T.; Hayakawa, Y.; Suzuki, K.; Suzuki, M.; Watanabe, M.

    1990-01-01

    Formation of free radicals in golden hamster embryo (GHE) cells in the frozen living state by gamma irradiation has been studied by electron spin resonance spectroscopy at 4.2 and 77 K. The relative yields of H atoms, OH radicals, and organic radicals trapped in the irradiated GHE cells are 12, 72, and 16%, respectively, of total radical yields. When dimethylsulfoxide (DMSO) is added to GHE cells at 77 K, a large quantity of CH2SOCH3 radicals (DMSO radicals) are formed after gamma irradiation. The yields of OH radicals are not affected by the addition of DMSO. When the GHE cell-DMSO mixtures are irradiated with gamma rays at 77 K and then warmed to 111 K, the OH radicals decay, whereas the DMSO radicals do not increase complementarily. Moreover, the decay rates of the OH radicals at 111 K do not depend upon the concentration of DMSO. Thus OH radicals do not react with DMSO during warming of the irradiated sample. When H atoms are produced by gamma irradiation of acid ice at 60 K, the decay rates of the H atoms at 77 K increase with increasing DMSO concentration, indicating that DMSO reacts with H atoms (CH3SOCH3 + H----.CH2SOCH3 + H2) at 77 K by quantum-mechanical tunneling. When the GHE cell-DMSO mixture is irradiated with gamma rays at 77 or 4.2 K in the dark, DMSO ions are produced in addition to DMSO radicals. Therefore it is concluded that DMSO does not scavenge OH radicals, but does capture H atoms, holes and/or electrons in the gamma-irradiated cells, resulting in the remarkable formation of DMSO radicals. This scavenger effect of DMSO may be related to the radioprotection of DMSO against cell killing

  7. Magnetic Resonance Studies of Proton Loss from Carotenoid Radical Cations

    Energy Technology Data Exchange (ETDEWEB)

    Kispert, Lowell D [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Focsan, A Ligia [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Konovalova, Tatyana A [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawrence, Jesse [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bowman, Michael K [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Molnar, Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deli, Jozsef [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2007-06-11

    Carotenoids, intrinsic components of reaction centers and pigment-protein complexes in photosynthetic membranes, play a photoprotective role and serve as a secondary electron donor. Before optimum use of carotenoids can be made in artificial photosynthetic systems, their robust nature in living materials requires extensive characterization of their electron transfer, radical trapping ability, stability, structure in and on various hosts, and photochemical behavior. Pulsed ENDOR and 2D-HYSCORE studies combined with DFT calculations reveal that photo-oxidation of natural zeaxanthin (I) and violaxanthin (II) on silica-alumina produces not only the carotenoid radical cations (Car•+) but also neutral radicals (#Car•) by proton loss from the methyl groups at positions 5 or 5', and possibly 9 or 9' and 13 or 13'. Notably, the proton loss favored in I at the 5 position by DFT calculations, is unfavorable in II due to the epoxide at the 5, 6 position. DFT calculations predict the isotropic methyl proton couplings of 8-10 MHz for Car•+ which agree with the ENDOR for carotenoid α-conjugated radical cations. Large α-proton hyperfine coupling constants (>10 MHz) determined from HYSCORE are assigned from the DFT calculations to neutral carotenoid radicals. Proton loss upon photolysis was also examined as a function of carotenoid polarity [Lycopene (III) versus 8'-apo-β-caroten-8'-al (IV)]; hydrogen bonding [Lutein (V) versus III]; host [silica-alumina versus MCM-41 molecular sieve]; and substituted metal in MCM-41. Loss of H+ from the 5(5'), 9(9') or 13(13') methyl positions has importance in photoprotection. Photoprotection involves nonphotochemical quenching (NPQ) in which 1Ch1* decays via energy transfer to the carotenoid which returns to the ground state by thermal dissipation; or via electron transfer to form a charge transfer state (I •+…Chl•-), lower in energy than 1Chl*. Formation of I •+ results in bond

  8. Magnetic Resonance Studies of Proton Loss from Carotenoid Radical Cations

    International Nuclear Information System (INIS)

    Kispert, Lowell D.; Focsan, A. Ligia; Konovalova, Tatyana A.; Lawrence, Jesse; Bowman, Michael K.; Dixon, David A.; Molnar, Peter; Deli, Jozsef

    2007-01-01

    Carotenoids, intrinsic components of reaction centers and pigment-protein complexes in photosynthetic membranes, play a photoprotective role and serve as a secondary electron donor. Before optimum use of carotenoids can be made in artificial photosynthetic systems, their robust nature in living materials requires extensive characterization of their electron transfer, radical trapping ability, stability, structure in and on various hosts, and photochemical behavior. Pulsed ENDOR and 2D-HYSCORE studies combined with DFT calculations reveal that photo-oxidation of natural zeaxanthin (I) and violaxanthin (II) on silica-alumina produces not only the carotenoid radical cations (Car ·+ ) but also neutral radicals ((number s ign)Car · ) by proton loss from the methyl groups at positions 5 or 5(prime), and possibly 9 or 9(prime) and 13 or 13(prime). Notably, the proton loss favored in I at the 5 position by DFT calculations, is unfavorable in II due to the epoxide at the 5, 6 position. DFT calculations predict the isotropic methyl proton couplings of 8-10 MHz for Car # center d ot# + which agree with the ENDOR for carotenoid π-conjugated radical cations. Large α-proton hyperfine coupling constants (>10 MHz) determined from HYSCORE are assigned from the DFT calculations to neutral carotenoid radicals. Proton loss upon photolysis was also examined as a function of carotenoid polarity (Lycopene (III) versus 8(prime)-apo-β-caroten-8(prime)-al (IV)); hydrogen bonding (Lutein (V) versus III); host (silica-alumina versus MCM-41 molecular sieve); and substituted metal in MCM-41. Loss of H + from the 5(5(prime)), 9(9(prime)) or 13(13(prime)) methyl positions has importance in photoprotection. Photoprotection involves nonphotochemical quenching (NPQ) in which 1 Ch1* decays via energy transfer to the carotenoid which returns to the ground state by thermal dissipation; or via electron transfer to form a charge transfer state (I # center d ot# + ...Chl # center d ot# - ), lower in

  9. Radical pancreaticoduodenectomy for benign disease.

    LENUS (Irish Health Repository)

    Kavanagh, D O

    2008-01-01

    Whipple\\'s procedure is the treatment of choice for pancreatic and periampullary malignancies. Preoperative histological confirmation of malignancy is frequently unavailable and some patients will subsequently be found to have benign disease. Here, we review our experience with Whipple\\'s procedure for patients ultimately proven to have benign disease. The medical records of all patients who underwent Whipple\\'s procedure during a 15-year period (1987-2002) were reviewed; 112 patients underwent the procedure for suspected malignancy. In eight cases, the final histology was benign (7.1%). One additional patient was known to have benign disease at resection. The mean age was 50 years (range: 30-75). The major presenting features included jaundice (five), pain (two), gastric outlet obstruction (one), and recurrent gastrointestinal haemorrhage (one). Investigations included ultrasound (eight), computerised tomography (eight), endoscopic retrograde cholangiopancreatography (seven; of these, four patients had a stent inserted and three patients had sampling for cytology), and endoscopic ultrasound (two). The pathological diagnosis included benign biliary stricture (two), chronic pancreatitis (two), choledochal cyst (one), inflammatory pseudotumour (one), cystic duodenal wall dysplasia (one), duodenal angiodysplasia (one), and granular cell neoplasm (one). There was no operative mortality. Morbidity included intra-abdominal collection (one), anastomotic leak (one), liver abscess (one), and myocardial infarction (one). All patients remain alive and well at mean follow-up of 41 months. Despite recent advances in diagnostic imaging, 8% of the patients undergoing Whipple\\'s procedure had benign disease. A range of unusual pathological entities can mimic malignancy. Accurate preoperative histological diagnosis may have allowed a less radical operation to be performed. Endoscopic ultrasound-guided fine needle aspirate (EUS-FNA) may reduce the need for Whipple\\'s operation

  10. Radical Pancreaticoduodenectomy for Benign Disease

    Directory of Open Access Journals (Sweden)

    D. O. Kavanagh

    2008-01-01

    Full Text Available Whipple's procedure is the treatment of choice for pancreatic and periampullary malignancies. Preoperative histological confirmation of malignancy is frequently unavailable and some patients will subsequently be found to have benign disease. Here, we review our experience with Whipple's procedure for patients ultimately proven to have benign disease. The medical records of all patients who underwent Whipple's procedure during a 15-year period (1987–2002 were reviewed; 112 patients underwent the procedure for suspected malignancy. In eight cases, the final histology was benign (7.1%. One additional patient was known to have benign disease at resection. The mean age was 50 years (range: 30–75. The major presenting features included jaundice (five, pain (two, gastric outlet obstruction (one, and recurrent gastrointestinal haemorrhage (one. Investigations included ultrasound (eight, computerised tomography (eight, endoscopic retrograde cholangiopancreatography (seven; of these, four patients had a stent inserted and three patients had sampling for cytology, and endoscopic ultrasound (two. The pathological diagnosis included benign biliary stricture (two, chronic pancreatitis (two, choledochal cyst (one, inflammatory pseudotumour (one, cystic duodenal wall dysplasia (one, duodenal angiodysplasia (one, and granular cell neoplasm (one. There was no operative mortality. Morbidity included intra-abdominal collection (one, anastomotic leak (one, liver abscess (one, and myocardial infarction (one. All patients remain alive and well at mean follow-up of 41 months. Despite recent advances in diagnostic imaging, 8% of the patients undergoing Whipple'’s procedure had benign disease. A range of unusual pathological entities can mimic malignancy. Accurate preoperative histological diagnosis may have allowed a less radical operation to be performed. Endoscopic ultrasound–guided fine needle aspirate (EUS-FNA may reduce the need for Whipple's operation in

  11. Photodynamically generated bovine serum albumin radicals

    DEFF Research Database (Denmark)

    Silvester, J A; Timmins, G S; Davies, Michael Jonathan

    1998-01-01

    Porphyrin-sensitized photoxidation of bovine serum albumin (BSA) results in oxidation of the protein at (at least) two different, specific sites: the Cys-34 residue giving rise to a thiyl radical (RS.); and one or both of the tryptophan residues (Trp-134 and Trp-214) resulting in the formation...... of tertiary carbon-centred radicals and disruption of the tryptophan ring system. In the case of porphyrins such as hematoporphyrin, which bind at specific sites on BSA, these species appear to arise via long-range transfer of damage within the protein structure, as the binding site is some distance from...... the ultimate site of radical formation. This transfer of damage is shown to depend on a number of factors including the conformation of the protein, the presence of blocking groups and pH. Alteration of the protein conformation results in radical formation at additional (or alternative) sites, as does blocking...

  12. Radical production in the radiolysis of benzene

    International Nuclear Information System (INIS)

    LaVerne, J.A.; Araos, M.S.

    1998-01-01

    Complete text of publication follows. Benzene is the prototypical aromatic compound and yet the radiation chemistry of the radicals formed in its radiolysis is not well understood. Temporal information on the yield of phenyl radical, the major radical produced in the radiolysis, is important for understanding the radiation chemistry of many other types of aromatic compounds including some polymers. The effects of track structure on the production of phenyl radicals have been examined using iodine-scavenging techniques. The variation of the yields of iodobenzene and the other major molecular products such as biphenyl as a function of iodine concentration gives a good indication of the competition kinetics occurring in particle tracks. Experimental results of the scavenger experiments will be shown and their implications in the radiolysis of condensed hydrocarbons will be discussed

  13. Radical Sustainable Innovation of office buildings

    DEFF Research Database (Denmark)

    Koch, Christian; Berker, Thomas; Koch-Ørvad, Nina

    2017-01-01

    by high degrees of newness in the entire life cycle. RSI should offer significant enhancements of known benefits, entirely new benefits, or substantial cost reductions, leading to the transformation of existing markets, the creation of sustainable growth, and global sustainability. Thus, if buildings were....../could be radically new. How to evaluate radicality is a major challenge. It is tentatively proposed, to use standards for sustainable office buildings. Standards are developed to accelerate the sustainable development but has to some extent come to constrain possibilities of radical innovation. As the criteria...... of newness is incorporated in standards, going beyond them, could be viewed as radical. Empirically a selection of international cases of office buildings with very high scores of BREEAM, LEED and DGNB are examined. Six selected cases were analysed more in detail, one of them, Geelens...

  14. Interactions between simple radicals and water

    International Nuclear Information System (INIS)

    Crespo-Otero, Rachel; Sanchez-Garcia, Elsa; Suardiaz, Reynier; Montero, Luis A.; Sander, Wolfram

    2008-01-01

    The interactions of the simple radicals CH 3 , NH 2 , OH, and F with water have been studied by DFT (UB3LYP/6-311++G(2d,2p)) and ab initio (RHF-UCCSD(T)/6-311++G(2d,2p)) methods. In this order the number of lone pairs (from zero to three), the electronegativity, and the strength of the X-H bonds increase (X = C, N, and O). The various minima of the radical-water complexes were located using the multiple minima hypersurface (MMH) approach which had previously been proven to be useful for closed-shell molecules. The role of the unpaired electron in hydrogen bonding was investigated using the natural bond orbital (NBO) analysis. A considerable contribution of the unpaired electron to the complex stabilization was only found for the methyl radical and the fluorine atom, whereas in the aminyl and the hydroxyl radical the role of the unpaired electron is negligible

  15. Psychopathology according to behaviorism: a radical restatement.

    Science.gov (United States)

    Pérez-Alvarez, Marino

    2004-11-01

    This article is a radical restatement of the predominant psychopathology, which is characterized by nosological systems and by its approach towards a neurobiological conception of the so-called mental disorders. The "radical" sense of this restatement is that of radical behaviorism itself. As readers will recall, "radical" applied to behaviorism means total (not ignoring anything that interests psychology), pragmatic (referring to the practical sense of knowledge), and it also derives from the Latin word for "root" (and thus implies change beginning at a system's roots or getting to the root of things, in this case, of psychological disorders). Based on this, I introduce the Aristotelian distinction of material and form, which, besides being behaviorist avant la lettre, is used here as a critical instrument to unmask the hoax of psychopathology as it is presented. The implications of this restatement are discussed, some of them already prepared for clinical practice.

  16. Radical-Local Teaching and Learning

    DEFF Research Database (Denmark)

    Hedegaard, Mariane; Chaiklin, Seth

    radical-local teaching and learning approach. The first half of the book introduces the idea of radical-local teaching and learning and develops the theoretical background for this perspective, drawing on the cultural-historical research tradition, particularly from Vygotsky, El'konin, Davydov......, and Aidarova. The second half of the book addresses the central concern of radical-local teaching and learning - how to relate educational practices to children's specific historical and cultural conditions. The experiment was conducted for an academic year in an afterschool programme in the East Harlem......Radical-Local Teaching and Learning presents a theoretical perspective for analyzing and planning educational programmes for schoolchildren. To realize both general societal interests and worthwhile personal development, the content of educational programmes for children must be grounded...

  17. Prison Radicalization: The New Extremist Training Grounds?

    National Research Council Canada - National Science Library

    Coffin, Jr., McKinley D

    2007-01-01

    As a nation with the largest prison population in the world, the United States has all the ingredients for criminals, extremists, and religious radicals to collaborate in producing a new breed of homegrown terrorist...

  18. Neo-liberal Governing of 'Radicals'

    DEFF Research Database (Denmark)

    Lindekilde, Lasse

    2012-01-01

    The Danish government’s counter-radicalization Action Plan of 2009 had intended and unintended effects. Primarily targeting Danish Muslims, it employs neoliberal governmentality approaches of governance through individual support and response, information and knowledge, empowerment, surveillance...

  19. Fast beam studies of free radical photodissociation

    Energy Technology Data Exchange (ETDEWEB)

    Neumark, D.M. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    The authors have developed a novel technique for studying the photodissociation spectroscopy and dynamics of free radicals. In these experiments, radicals are generated by laser photodetachment of a fast (6-8 keV) mass-selected negative ion beam. The resulting radicals are photodissociated with a second laser, and the photofragments are collected and detected with high efficiency using a microchannel plate detector. The overall process is: ABC{sup -} {yields} ABC + e{sup -} {yields} A + BC, AB + C. Two types of fragment detection schemes are used. To map out the photodissociation cross-section of the radical, the photodissociation laser is scanned and the total photofragment yield is measured as a function of wavelength. In other experiments, the photodissociation frequency is fixed and the photofragment masses, kinetic energy release, and scattering angle is determined for each photodissociation event.

  20. Analysis of radicals of irradiated garlic

    International Nuclear Information System (INIS)

    Kameya, Hiromi; Kaimori, Yoshihiko; Ukai, Mitsuko

    2010-01-01

    The detection method of gamma ray irradiated garlic using Electron Spin Resonance(ESR)spectroscopy was studied. The ESR spectrum was consisted of one singlet signal at g=2.00. This signal is due to an organic free radical. Upon irradiation, the intensity of the signal was increased. Also two signals due to cellulose radical were detected nearby the singlet. The intensity of the singlet signal was increased as depend on the increase of the irradiation dose level. (author)

  1. Western radicalization: rethinking the psychology of terrorism

    OpenAIRE

    Pierson, Vern

    2017-01-01

    Approved for public release; distribution is unlimited The U.S. strategy to counter violent extremism relies heavily on the expert consensus that terrorists are engaging in political group speak and are by nature psychologically normal. Thus, anyone is susceptible to radicalization. To counter radicalization, finding answers is like finding a needle in a haystack. However, in the psychologically similar phenomenon of arson by firefighter—when a firefighter deliberately sets and then exting...

  2. Free radicals trapped in polyethylene matrix

    International Nuclear Information System (INIS)

    Shimada, S.; Maeda, M.; Hori, Y.; Kashiwabara, H.

    1977-01-01

    Two types of alkyl radicals were found to be trapped in irradiated crystals grown from polyethylene solution. One of them corresponds to the broad sextet pattern of the e.s.r. spectrum and the other corresponds to the sharp sextet pattern. The free radicals attributed to the broad sextet began to disappear at a lower temperature than the temperature at which the free radicals attributed to the sharp sextet disappeared. When butadiene molecules were brought into contact with the specimen, the decay of the free radicals corresponding to the broad sextet was accelerated. When the specimen was subjected to fuming nitric acid treatment, no broad sextet was observed. The mat of the crystals was aligned so that the c-axes of its crystallites were perpendicular to its surface. The broad sextet showed no anisotropy when the angle between the direction of applied magnetic field and that of the c-axis of the crystallite was varied. On the other hand, the sharp component of the spectrum showed apparent anisotropy. It can be concluded that the broad component comes from the free radicals trapped in the lamellar surface and the sharp component is attributed to the free radicals trapped in the inner part of the crystallite. (author)

  3. Development of a new free radical absorption capacity assay method for antioxidants: aroxyl radical absorption capacity (ARAC).

    Science.gov (United States)

    Nagaoka, Shin-ichi; Nagai, Kanae; Fujii, Yuko; Ouchi, Aya; Mukai, Kazuo

    2013-10-23

    A new free radical absorption capacity assay method is proposed with use of an aroxyl radical (2,6-di-tert-butyl-4-(4'-methoxyphenyl)phenoxyl radical) and stopped-flow spectroscopy and is named the aroxyl radical absorption capacity (ARAC) assay method. The free radical absorption capacity (ARAC value) of each tocopherol was determined through measurement of the radical-scavenging rate constant in ethanol. The ARAC value could also be evaluated through measurement of the half-life of the aroxyl radical during the scavenging reaction. For the estimation of the free radical absorption capacity, the aroxyl radical was more suitable than the DPPH radical, galvinoxyl, and p-nitrophenyl nitronyl nitroxide. The ARAC value in tocopherols showed the same tendency as the free radical absorption capacities reported previously, and the tendency was independent of an oxygen radical participating in the scavenging reaction and of a medium surrounding the tocopherol and oxygen radical. The ARAC value can be directly connected to the free radical-scavenging rate constant, and the ARAC method has the advantage of treating a stable and isolable radical (aroxyl radical) in a user-friendly organic solvent (ethanol). The ARAC method was also successfully applied to a palm oil extract. Accordingly, the ARAC method would be useful in free radical absorption capacity assay of antioxidative reagents and foods.

  4. Free radicals in wood induced by γ-radiation

    International Nuclear Information System (INIS)

    Xu Honglin; Zhang Wenhui

    1994-01-01

    The free radicals in wood induced by γ-radiation were studied by electron spin resonance. The fine structure of the ESR signal from sawdust samples irradiated could be resolved into various radicals. These free radicals have a very long lifetime. The major spectrum for the free radicals will exponentially increased along with the radiation dose according to Y 1-Exp(-α a D). The intensity of radiation radicals is dependent on tree species. The stronger the intensity of mechanic free radicals is, the stronger the intensity of radiation free radicals

  5. Functionalization of lanthanum hydroxide nanowires by atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Zhou Mi; Yuan Jinying; Yuan Weizhong; Yin Yingwu; Hong Xiaoyin

    2007-01-01

    Atom transfer radical polymerization (ATRP) has been used to prepare a core-shell hybrid nanostructure successfully: a hard core of single-crystalline lanthanum hydroxide nanowires and a soft shell of polystyrene (PS) brushes. Transmission electron microscopy (TEM) images indicated that the resulting products presented special structures and different thicknesses of polymer layers. The chemical components and grafted PS quantities of the samples were measured by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The polymers showed narrow polydispersity, which proved that the lanthanum hydroxide nanowires initiated the 'living'/controlled polymerization of styrene. With the modifiability of lanthanum hydroxide nanowires, the solubility increased, which affords a new way to functionalize nanowires

  6. Anti-social behaviour, community and radical moral communitarianism

    Directory of Open Access Journals (Sweden)

    Roger Hopkins-Burke

    2015-12-01

    Full Text Available This article offers an insight into the lives of individuals who are repeat victims of antisocial behaviour (ASB. Drawing on data derived from 15 case studies, the authors demonstrate the plight that such victims endure on a daily basis. The research reveals that a number of victims feel abandoned by their communities and the authorities and, how for many, there is an overwhelming sense of being “trapped” within their own homes. The article also offers evidence to support previous claims that police crime data only captures a small proportion of the actual number of incidents of ASB that occur. We conclude by proposing an emphasis on individual and community responsibility and suggest that by adopting a radical moral communitarian approach ASB could be reduced as part of rebuilding communities.

  7. Rediscovering joy in costly and radical discipleship in mission

    Directory of Open Access Journals (Sweden)

    C.J.P. (Nelus Niemandt

    2016-11-01

    The link between mission, evangelism and discipleship was developed as a basis to expand the understanding of evangelism as an invitation to personal conversion and discipleship. Discipleship was defined as participating in the Triune God’s life-giving mission and as being on a journey towards flourishing life. It showed that the gospel message of joy, good news and life in fullness serves as a counterculture against the prevailing rhetoric of religious and secular prosperity gospels, consumerism and individualism. It also warned that discipleship in mission is costly and radical. Discipleship is a life of generosity and service, where the true disciple delights in justice, gives generously and cares for the weak. The research concluded with a discussion of practical holistic practices of embodied discipleship – practices that will form habits where disciples will live a flourishing life.

  8. "Views of democracy and peace” inequality, minorities and radical democracy

    Directory of Open Access Journals (Sweden)

    TizianoTelleschi

    2012-09-01

    Full Text Available Democracy is a moral and practical system conveying living proximity, including definition of love-AGAPE, conflict, inequality, power. First we highlight “what it is” love and “what it is” power. Then, in order to overcome inequality weapply the love theory to an acknowledgment theory to figure out the mediator figure, that is able to build a social space where love-AGAPE may thrive and power may be restored to its relational nature, that is negotiable. From this point we go on analyzing the distributed power (horizontal. At last, thank to A. Gramsci’s hegemony notion, we point out the ideal of radical democracy as the most fertile along the others, to which a common action from different types of qualified mediators should tend.

  9. Synthesis and Characterization of Ethylenedithio-MPTTF-PTM Radical Dyad as a Potential Neutral Radical Conductor

    DEFF Research Database (Denmark)

    Souto, Manuel; Bendixen, Dan; Jensen, Morten

    2016-01-01

    During the last years there has been a high interest in the development of new purely-organic single-component conductors. Very recently, we have reported a new neutral radical conductor based on the perchlorotriphenylmethyl (PTM) radical moiety linked to a monopyrrolo-tetrathiafulvalene (MPTTF...

  10. How to counter radical narratives: Dutch deradicalization policy in the case of Moluccan and Islamic radicals

    NARCIS (Netherlands)

    Demant, F.; de Graaf, B.

    2010-01-01

    This article deals with the role of government in encouraging the decline of radical movements. The question posed is: "Which story can the government tell to encourage the decline of radical groups and the disengagement of their members?" The article makes use of the survey of factors promoting

  11. Radical Transversal Lightlike Submanifolds of Indefinite Para-Sasakian Manifolds

    OpenAIRE

    Shukla S.S.; Yadav Akhilesh

    2014-01-01

    In this paper, we study radical transversal lightlike submanifolds and screen slant radical transversal lightlike submanifolds of indefinite para-Sasakian manifolds giving some non-trivial examples of these submanifolds. Integrability conditions of distributions D and RadTM on radical transversal lightlike submanifolds and screen slant radical transversal lightlike submanifolds of indefinite para-Sasakian manifolds, have been obtained. We also study totally contact umbilical radical transvers...

  12. Radical-Local Teaching and Learning

    DEFF Research Database (Denmark)

    Hedegaard, Mariane; Chaiklin, Seth

    Radical-Local Teaching and Learning presents a theoretical perspective for analyzing and planning educational programmes for schoolchildren. To realize both general societal interests and worthwhile personal development, the content of educational programmes for children must be grounded in the l......Radical-Local Teaching and Learning presents a theoretical perspective for analyzing and planning educational programmes for schoolchildren. To realize both general societal interests and worthwhile personal development, the content of educational programmes for children must be grounded...... radical-local teaching and learning approach. The first half of the book introduces the idea of radical-local teaching and learning and develops the theoretical background for this perspective, drawing on the cultural-historical research tradition, particularly from Vygotsky, El'konin, Davydov......, and Aidarova. The second half of the book addresses the central concern of radical-local teaching and learning - how to relate educational practices to children's specific historical and cultural conditions. The experiment was conducted for an academic year in an afterschool programme in the East Harlem...

  13. Radical-pair based avian magnetoreception

    Science.gov (United States)

    Procopio, Maria; Ritz, Thorsten

    2014-03-01

    Behavioural experiments suggest that migratory birds possess a magnetic compass sensor able to detect the direction of the geomagnetic. One hypothesis for the basis of this remarkable sensory ability is that the coherent quantum spin dynamics of photoinduced radical pair reactions transduces directional magnetic information from the geomagnetic field into changes of reaction yields, possibly involving the photoreceptor cryptochrome in the birds retina. The suggested radical-pair based avian magnetoreception has attracted attention in the field of quantum biology as an example of a biological sensor which might exploit quantum coherences for its biological function. Investigations on such a spin-based sensor have focussed on uncovering the design features for the design of a biomimetic magnetic field sensor. We study the effects of slow fluctuations in the nuclear spin environment on the directional signal. We quantitatively evaluate the robustness of signals under fluctuations on a timescale longer than the lifetime of a radical pair, utilizing two models of radical pairs. Our results suggest design principles for building a radical-pair based compass sensor that is both robust and highly directional sensitive.

  14. Vibronic Spectroscopy of the Phenylcyanomethyl Radical

    Science.gov (United States)

    Mehta, Deepali N.; Kidwell, Nathanael M.; Zwier, Timothy S.

    2011-06-01

    Resonance stabilized radicals (RSRs) are thought to be key intermediates in the formation of larger molecules in planetary atmospheres. Given the nitrogen-rich atmosphere of Titan, and the prevalence of nitriles there, it is likely that nitrile and isonitrile RSRs could be especially important in pathways leading to the formation of more complex nitrogen-containing compounds and the aerosols ("tholins") that are ultimately produced. In this talk, the results of a gas phase, jet-cooled vibronic spectroscopy study of the phenylcyanomethyl radical (C_6H_5.{C}HCN), the nitrogen-containing analog of the 1-phenylpropargyl radical, will be presented. A resonant two color photon ionization spectrum over the range 21,350-22,200 Cm-1 (450.0-468.0 nm) has been recorded, and the D_0-D_1 origin band has been tentatively identified at 21,400 Cm-1. Studies identifying the ionization threshold, and characterizing the vibronic structure will also be presented. An analogous study of the phenylisocyanomethyl radical, C_6H_5.{C}HNC, is currently being pursued for comparison with that of phenylcyanomethyl radical.

  15. Introducing Stable Radicals into Molecular Machines.

    Science.gov (United States)

    Wang, Yuping; Frasconi, Marco; Stoddart, J Fraser

    2017-09-27

    Ever since their discovery, stable organic radicals have received considerable attention from chemists because of their unique optical, electronic, and magnetic properties. Currently, one of the most appealing challenges for the chemical community is to develop sophisticated artificial molecular machines that can do work by consuming external energy, after the manner of motor proteins. In this context, radical-pairing interactions are important in addressing the challenge: they not only provide supramolecular assistance in the synthesis of molecular machines but also open the door to developing multifunctional systems relying on the various properties of the radical species. In this Outlook, by taking the radical cationic state of 1,1'-dialkyl-4,4'-bipyridinium (BIPY •+ ) as an example, we highlight our research on the art and science of introducing radical-pairing interactions into functional systems, from prototypical molecular switches to complex molecular machines, followed by a discussion of the (i) limitations of the current systems and (ii) future research directions for designing BIPY •+ -based molecular machines with useful functions.

  16. Analysis of radicals induced in irradiated foods

    International Nuclear Information System (INIS)

    Kishida, Keigo; Kaimori, Yoshihiko; Kawamura, Shoei; Sakamoto, Yuhki; Nakamura, Hideo; Ukai, Mitsuko; Kikuchi, Masahiro; Shimoyama, Yuhei; Kobayashi, Yasuhiko

    2012-01-01

    By electron spin resonance (ESR) spectroscopy, we revealed free radicals in γ-ray irradiated foods; black pepper, green coffee bean and ginseng. We also analyzed the decay behavior of radiation induced free radicals during storage of irradiated foods. The ESR spectrum of experimental irradiated foods consists of a sextet signal centered at g=2.0 and a singlet signal at the same g-value position and a singlet signal at g=4.0. The singlet signal at g=2.0 is originated from organic free radicals and its peak intensity showed the dependence of γ-ray irradiation dose levels. The signal intensity was decreased during storage. Only after 3 hours of radiation treatment the peak intensity was decreased fast and after that the intensity was decreased slowly. The relaxation times, T 1 and T 2 , of radiation induced free radicals showed the variations before and after irradiation. During long time storage period it was shown that T 1 was increased and T 2 was decreased. By analysis of decay process using the simulation methods based on the theory of reaction speed, it is considered that at least two kinds of radicals were induced in irradiated foods during long time storage. (author)

  17. Vinylcyclopropylacyl and polyeneacyl radicals. Intramolecular ketene alkyl radical additions in ring synthesis.

    Science.gov (United States)

    De Boeck, Benoit; Herbert, Nicola M A; Harrington-Frost, Nicole M; Pattenden, Gerald

    2005-01-21

    Treatment of a variety of substituted vinylcyclopropyl selenyl esters, e.g. 11, with Bu(3)SnH-AIBN in refluxing benzene leads to the corresponding acyl radical intermediates, which undergo rearrangement and intramolecular cyclisations via their ketene alkyl radical equivalents producing cyclohexenones in 50-60% yield. By contrast, treatment of conjugated triene selenyl esters, e.g. 32, with Bu(3)SnH-AIBN produces substituted 2-cyclopentenones via intramolecular cyclisations of their ketene alkyl radical intermediates. Under the same radical-initiating conditions the selenyl esters derived from o-vinylbenzoic acid and o-vinylcinnamic acid undergo intramolecular cyclisations producing 1-indanone and 5,6-dihydrobenzocyclohepten-7-one respectively in 60-70% yields. A tandem radical cyclisation from the alpha,beta,gamma,delta-diene selenyl ester 31 provides an expeditious synthesis of the diquinane 35 in 69% yield.

  18. Fragmentation characteristics of the unstable [CH3 CO][radical sign] radicals generated by neutralization of [CH3CO]+ cations

    Science.gov (United States)

    Hop, C. E. C. A.; Holmes, J. L.

    1991-03-01

    The stability and fragmentation characteristics of [CH3 CO][radical sign] radicals, generated by vertical charge exchange between acetyl cations and permanent gases or metal vapours (He, Xe, NO, Cd, Na and K), were examined mass spectrometrically. Two dissociation reactions were observed, the losses of CH[radical sign]3 and H[radical sign]. The H[radical sign] loss reaction, the higher energy dissociation, became of greater importance as the exothermicity of the charge exchange was increased. Based on the analysis of the kinetic energy releases it was concluded that these decompositions arose from the population of two excited states of the [CH3 CO][radical sign] radical.

  19. [Living better or living longer].

    Science.gov (United States)

    Sauvy, A

    1987-01-01

    It has been just 2 centuries since France began to struggle seriously against mortality and excess fertility. Life expectancy, which for millenia had been under 30 years at birth, began to increase because of the discovery of effective treatments, improved production and standards of living, and access of large numbers of persons to health care. France, in the 2nd half of the 18th century, became the first country in which fertility regulation was achieved on a wide scale. The failure of England, a country of similar culture, to follow suit until a century later remains unexplained. After World War II, simple and fairly inexpensive means of mortality control, such as vaccines and water purifiers, became widely distributed throughout the developing world. These countries, which traditionally had mortality rates of 35 or 40/1000 and fertility of 40-45/1000, experienced rapid declines in mortality rates while their fertility remained constant or even increased. Because antinatal techniques diffused so much more slowly, the equilibrium of births and deaths was disturbed as rates of increase of 2 or 3% per year became common. Although the inhabitants of poor countries were not concerned, perhaps through ignorance of what was occurring, the rich countries were alarmed by the increase. Their principal objective became to spread contraception in the poor countries. The available methods at the time, however, were none too reliable. When oral contraceptive pills became available, fertility dropped to very low levels in Europe but such factors as cost and illiteracy discouraged use in many underdeveloped countries. Fertility declined in a few insular states such as Hong Kong, Taiwan, and Singapore even before the appearance of pills. Life expectancies in developing countries except a few in Africa have increased since World War II and are now higher than in Europe at the turn of the century. "Health for all by the year 2000" is an astonishing slogan for a serious

  20. Effect of metal complexation to anti-inflammatory over the action against oxidative and free radicals: ketoprofen action; Efeito da complexacao de metais aos antiinflamatorios na acao contra agentes oxidativos e radicais livres: acao do cetoprofeno

    Energy Technology Data Exchange (ETDEWEB)

    Manente, Francine Alessandra; Mello, Lucas Rosolen de Almeida; Vellosa, Jose Carlos Rebuglio [UEPG, Universidade Estadual de Ponta Grossa, Departamento de Analises Clinicas eToxicologicas, Ponta Grossa, PR (Brazil); Khalil, Omar Arafat Kdudsi [IFG, Instituto Federal de Goias, Campus de Formosa, Formosa - GO (Brazil); Carvalho, Claudio Teodoro de [UFGD, Universidade Federal da Grande Dourados, Faculdade de Ciencias Exatas e Tecnologias, Dourados-MS (Brazil); Bannach, Gilbert [UNESP, Universidade Estadual Paulista Julio de Mesquita Filho, Faculdade de Ciencias de Bauru, Bauru, SP (Brazil)

    2011-07-01

    Free radicals are highly reactive species generated in living organisms for the purpose of protection. However, in some circumstances, they are responsible for the occurrence or aggravation of tissue damage. Many anti-inflammatory drugs have a direct effect on free radicals and not radical reactive species, which contributes to its actions against inflammation. Ketoprofen is a nonsteroidal anti-inflammatory agent that generates free radicals by photo irradiation and has an important hemolytic effect with that. The complexation of metals to different drugs has been used as a strategy to improve the pharmacological action of different molecules and reduce their side effects. This paper presents the results of ketoprofen and their metallic complexes action on erythrocytes and free radicals. It was observed that the cerium enhances the scavenger properties of ketoprofen on free radicals, while copper enhances its action over non-radical oxidants. Copper also reduced the hemolytic effect presented by ketoprofen meanwhile its cerium derivative maintained it. (author)

  1. Time resolved resonance Raman spectra of anilino radical and aniline radical cation

    International Nuclear Information System (INIS)

    Tripathi, G.N.R.; Schuler, R.H.

    1987-01-01

    We report, in this paper, submicrosecond time resolved resonance Raman spectra of anilino radical and its radical cation as observed in pulse radiolytic studies of the oxidation of aniline in aqueous solution. By excitation in resonance with the broad and weak electronic transition of anilino radical at 400 nm (ε--1250 M -1 cm -1 ) we have observed, for the first time, the vibrational features of this radical. The Wilson ν 8 /sub a/ ring stretching mode at 1560 cm -1 is most strongly resonance enhanced. The ν 7 /sub a/ CN stretching band at 1505 cm -1 , which is shifted to higher frequency by 231 cm -1 with respect to aniline, is also prominent. The frequency of this latter mode indicates that the CN bond in the radical has considerable double bond character. The Raman spectrum of aniline radical cation, excited in resonance with the --425 nm electronic absorption (ε--4000 M -1 cm -1 ), shows features which are similar to phenoxyl radical. Most of the observed frequencies of this radical in solution are in good agreement with vibrational energies determined by recent laser photoelectron spectroscopic studies in the vapor phase. The bands most strongly enhanced in the resonance Raman spectrum are, however, weak in the photoelectron spectrum. While the vibrational frequencies observed for anilino radical and its isoelectronic cation are quite similar, the resonance enhancement patterns are very different. In particular the ν 14 b 2 mode of anilino radical observed at 1324 cm -1 is highly resonance enhanced because of strong vibronic coupling between the 400 nm 2 A 2 -- 2 B 1 and the higher 2 B 1 -- 2 B 1 electronic transitions

  2. Resveratrol products resulting by free radical attack

    Energy Technology Data Exchange (ETDEWEB)

    Bader, Yvonne; Quint, R.M. [Section Radiation Biology, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [Section Radiation Biology, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna (Austria)], E-mail: nikola.getoff@univie.ac.at

    2008-06-15

    Trans-resveratrol (trans-3,4',5-trihydroxystilbene; RES), which is contained in red wine and many plants, is one of the most relevant and extensively investigated stilbenes with a broad spectrum of biological activities. Among other duties, RES has been reported to have anti-carcinogenetic activities, which could be attributed to its antioxidant properties. The degradation of RES was studied under various conditions. The products (aldehydes, carboxylic acids, etc.) generated from RES by the attack of free radicals were registered as a function of the radical concentration (absorbed radiation dose). Based on the obtained data it appears that the OH radicals are initiating the rather complicated process, which involves of the numerous consecutive reactions. A possible starting reaction mechanism is presented.

  3. Optimal pain management for radical prostatectomy surgery

    DEFF Research Database (Denmark)

    Joshi, Grish P; Jaschinski, Thomas; Bonnet, Francis

    2015-01-01

    BACKGROUND: Increase in the diagnosis of prostate cancer has increased the incidence of radical prostatectomy. However, the literature assessing pain therapy for this procedure has not been systematically evaluated. Thus, optimal pain therapy for patients undergoing radical prostatectomy remains...... controversial. METHODS: Medline, Embase, and Cochrane Central Register of Controlled Trials were searched for studies assessing the effects of analgesic and anesthetic interventions on pain after radical prostatectomy. All searches were conducted in October 2012 and updated in June 2015. RESULTS: Most...... treatments studied improved pain relief and/or reduced opioid requirements. However, there were significant differences in the study designs and the variables evaluated, precluding quantitative analysis and consensus recommendations. CONCLUSIONS: This systematic review reveals that there is a lack...

  4. Customers as Partners in Radical Service Innovation

    DEFF Research Database (Denmark)

    Scupola, Ada; Nicolajsen, Hanne Westh

    2009-01-01

      Purpose- The main purpose of this paper is to investigate customer involvement and related challenges in radical service innovations in engineering consulting services Design/methodology/approach - The paper uses a case study approach and so called rich descriptions to investigate customer...... involvement, roles and related challenges and conditions in radical service innovations.Findings- One main finding is that customers can engage in radical service innovations in engineering consultancy services and may play a decisive role. In doing this they most likely take on all the three user involvement...... roles defined in the literature of New Service and New Product Development. Also a number of conditions are found to be necessary in order for this collaboration to succeed. The conclusion is that another understanding and handling of the customer/supplier relation is needed along with a need...

  5. Radiation chemistry of aromatic dimer radical cations

    International Nuclear Information System (INIS)

    Okamoto, Kazumasa; Tagawa, Seiichi

    2009-01-01

    π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)

  6. Formation of stable radicals during perfluoroalkane radiolysis

    International Nuclear Information System (INIS)

    Allayarov, S.R.; Demidov, S.V.; Kiryukhin, D.P.; Mikhajlov, A.I.; Barkalov, I.M.

    1984-01-01

    Accumulation and stabilization kinetics of perfluoroalkyls during α-radiolysis ( 60 Co) of perfluoralkanes (PFA) in a wide temperature range for different PFA fractions differing in the average molecular weight, is investigated. It is noted that low temperature (PFA) radiolysis (77 K) is of a linear nature of accumulation of stabilized radicals up to doses of approximately 700 KGy. In the case of PFA radiolysis at 300 K radiation yields of stable radicals are somewhat lower than at 47 K and at doses of 200-300 KGy, their accumulation ceases. It is shown that kinetics of formation and accumulation of stable radicals does not depend on molecular mass and PFA fraction viscosity. Perfluoroalkyl stability is explained by intra molecular conformation spheric insulation of the free valency. Perfluoroalkyl stability in different PFA fractions in a wide time range in different media is investigated

  7. Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, Fabián H.; Gómez, Jorge E.; Espinal, José H.; Sandoval, Junior E., E-mail: junior.sandoval@correounivalle.edu.co

    2016-12-15

    In the present study, porous silica particles as well as impervious fused-silica wafers and capillary tubes were modified with hydrophilic polymers (hydroxylated polyacrylamides and polyacrylates), using a surface-confined grafting procedure based on atom transfer radical polymerization (ATRP) which was also surface-initiated from α-bromoisobutyryl groups. Initiator immobilization was achieved by hydrosilylation of allyl alcohol on hydride silica followed by esterification of the resulting propanol-bonded surface with α-bromoisobutyryl bromide. Elemental analysis, IR and NMR spectroscopies on silica micro-particles, atomic force microscopy, ellipsometry and profilometry on fused-silica wafers, as well as CE on fused-silica tubes were used to characterize the chemically modified silica substrate at different stages. We studied the effect of monomer concentration as well as cross-linker on the ability of the polymer film to reduce electroosmosis and to prevent protein adsorption (i. e., its non-fouling capabilities) and found that the former was rather insensitive to both parameters. Surface deactivation towards adsorption was somewhat more susceptible to monomer concentration and appeared also to be favored by a low concentration of the cross-linker. The results show that hydrophilic polyacrylamide and polyacrylate coatings of controlled thickness can be prepared by ATRP under very mild polymerization conditions (aqueous solvent, room temperature and short reaction times) and that the coated capillary tubes exhibit high efficiencies for protein separations (0.3–0.6 million theoretical plates per meter) as well as long-term hydrolytic stability under the inherently harsh conditions of capillary isoelectric focusing. Additionally, there was no adsorption of lysozyme on the coated surface as indicated by a complete recovery of the basic enzyme. Furthermore, since polymerization is confined to the inner capillary surface, simple precautions (e.g., solution

  8. Hearing Status after Radical Mastoidectomy without Tympanoplasty.

    Science.gov (United States)

    Khan, Shamaila Nawaz; Udaipurwala, Iqbal Hussain; Mehmood, Talat; Rahat, Zahid Mehmood

    2017-12-01

    To find out the impairment of hearing associated with radical mastoidectomy by measuring the quantitative difference in the functional hearing level before and after radical mastoidectomy operation without tympanoplasty. Cross-sectional comparative study. Department of Otorhinolaryngology and Head Neck Surgery, Bahawal Victoria Hospital, Bahawalpur and PNS Shifa Hospital, Karachi, from November 2009 to January 2013. Eighty-five patients, diagnosed clinically as chronic suppurative otitis media with extensive cholesteatoma having history of ear discharge and hearing impairment for more than 6 weeks duration and requiring radical mastoidectomy for treatment, were included in this study. Pure tone audiogram was done before and after radical mastoidectomy. Hearing impairment was compared in each patient before and after the operation. Among the 85 patients, 54 (63.5%) were males and 31 (36.5%) were females, with the age ranged between 18 to 63 years, mean age being 42.31 4.8 years. The mean increase in hearing loss after radical mastoidectomy in air conduction was 7.19 dB, bone conduction was 4.16 dB, and air-bone gap was 3.75 dB (0.001). The ear became dry and safe in 82 patients (96.5%) out of a total of 85, and only 3 patients required revision surgery at a second stage. Radical mastoidectomy has a least negligible effect on hearing status and one should not limit this technique due to the concern of aggravated hearing in patients with extensive cholesteatoma at the cost of dry and safe ears, which should be of prime importance.

  9. Synthesis, Characterization and Bulk Properties of Amphiphilic Copolymers Containing Fluorinated Methacrylates from Sequential Copper-Mediated Radical Polymerization

    DEFF Research Database (Denmark)

    Hansen, Natanya Majbritt Louie; Gerstenberg, Michael; Haddleton, David M.

    2008-01-01

    acrylate (MEA), and poly(ethylene glycol) methyl ether methacrylate (PEGMA) by Atom Transfer Radical Polymerization. A kinetic study of the 3FM homopolymerization initiated with ethyl bromoisobutyrate and Cu(I)Br/N-(n-propyl)-2-pyridylmethanimine reveals a living/ controlled polymerization in the range 80...

  10. Exploring how lead users develop radical innovation

    DEFF Research Database (Denmark)

    Lettl, Christopher; Gemuenden, Hans Georg; Hienerth, C.

    2008-01-01

    in order to transform their radically new solutions into functional prototypes and then to convince established manufacturers of the technological and market potential of their innovations. Using a comparative case study design in the high-tech field of medical equipment technology, we find that individual...... the supply of diversified knowledge, the development and coordination of a network for further development of the innovation, and initial tests of technical or market feasibility. Our findings have implications for manufacturing firms that wish to design radical innovation projects with (individual) lead...

  11. Preparation and study of dialkyl nitroxide radicals

    International Nuclear Information System (INIS)

    Chenavas, P.

    1969-01-01

    These radicals are obtained by oxidation of N-hydroxy-imides with lead tetracetate or p-nitro-perbenzoic acid. These imides are prepared by heating dicarboxylic acids anhydrides with benzyloxy-amine followed by catalytic hydrogenation of N-benzyloxy-imides so obtained. Two series of radicals have mainly been studied, the first concerning five-membered cyclic imides, the second six-membered cyclic imides, these molecules having methyls substituents or no on the carbon ring. N. M. R. spectra of some O-benzyl-imides have been analysed. These different results have made it possible to study the conformation and stereochemistry of these imides. (author) [fr

  12. RADICAL. Radiation information centre with analysing logic

    International Nuclear Information System (INIS)

    Rantanen, H.

    1998-01-01

    in an emergency, the production of data is overwhelming and the need of accurate and up-to-date information is essential. In Finland a new system (RADICAL) has been developed in order to automatically collect and maintain an overall view of the radiation situation and to facilitate the analysis of the consequences of any radiation incident. The project was started in the beginning of 1992 and the system was operational in summer 1994. The main objectives of the development process and how they are being fulfilled with the RADICAL system are discussed. (author)

  13. Dibromine radical anion reactions with heme enzymes

    International Nuclear Information System (INIS)

    Gebicka, L.; Gebicki, J.L.

    1996-01-01

    Reactions of Br 2 radical anion with heme enzymes, catalase horseradish peroxidase, have been studied by pulse radiolysis. It has been found that Br 2 - does not react with the heme centre of investigated enzymes. Dibromine radical anion reacts with tryptophan residues of catalase without any influence on the activity of catalase. It is suggested that in pulse radiolysis studies, where horseradish peroxidase is at about tenfold excess toward Br 2 - , the enzyme is modified rather by Br 2 , than by Br 2 - . (author). 26 refs., 3 figs

  14. Radical Islamism and Migrant Integration in Denmark

    DEFF Research Database (Denmark)

    Goli, Marco; Rezaei, Shahamak

    2011-01-01

    It has been suggested that alienation and failed integration may be causes of “Homegrown Radical Islamism” in Western societies. Western countries often expect that migrants and their descendants residing there as citizens will embrace or support common democratic ideals as a predicate for – or c......It has been suggested that alienation and failed integration may be causes of “Homegrown Radical Islamism” in Western societies. Western countries often expect that migrants and their descendants residing there as citizens will embrace or support common democratic ideals as a predicate...

  15. Resonance ionization detection of combustion radicals

    Energy Technology Data Exchange (ETDEWEB)

    Cool, T.A. [Cornell Univ., Ithaca, NY (United States)

    1993-12-01

    Fundamental research on the combustion of halogenated organic compounds with emphasis on reaction pathways leading to the formation of chlorinated aromatic compounds and the development of continuous emission monitoring methods will assist in DOE efforts in the management and disposal of hazardous chemical wastes. Selective laser ionization techniques are used in this laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames.

  16. Competing with the radical right: Distances between the European radical right and other parties on typical radical right issues

    NARCIS (Netherlands)

    Immerzeel, T.; Lubbers, M.; Coffé, H.

    2016-01-01

    The popularity of European Radical Right Populist parties (RRPs) has led to investigations into the distances between RRPs' and other parties' stances regarding immigration. This article adds to this literature by investigating the distance between RRPs and the other parties on a wider variety of

  17. Competing with the radical right. Distances between the European radical right and other parties on typical radical right issues

    NARCIS (Netherlands)

    Immerzeel, T.; Lubbers, M.; Coffe, H.R.

    2015-01-01

    The popularity of European Radical Right Populist parties (RRPs) has led to investigations into the distances between RRPs’ and other parties’ stances regarding immigration. This article adds to this literature by investigating the distance between RRPs and the other parties on a wider variety of

  18. Serum Hydroxyl Radical Scavenging Capacity as Quantified with Iron-Free Hydroxyl Radical Source

    Science.gov (United States)

    Endo, Nobuyuki; Oowada, Shigeru; Sueishi, Yoshimi; Shimmei, Masashi; Makino, Keisuke; Fujii, Hirotada; Kotake, Yashige

    2009-01-01

    We have developed a simple ESR spin trapping based method for hydroxyl (OH) radical scavenging-capacity determination, using iron-free OH radical source. Instead of the widely used Fenton reaction, a short (typically 5 seconds) in situ UV-photolysis of a dilute hydrogen peroxide aqueous solution was employed to generate reproducible amounts of OH radicals. ESR spin trapping was applied to quantify OH radicals; the decrease in the OH radical level due to the specimen’s scavenging activity was converted into the OH radical scavenging capacity (rate). The validity of the method was confirmed in pure antioxidants, and the agreement with the previous data was satisfactory. In the second half of this work, the new method was applied to the sera of chronic renal failure (CRF) patients. We show for the first time that after hemodialysis, OH radical scavenging capacity of the CRF serum was restored to the level of healthy control. This method is simple and rapid, and the low concentration hydrogen peroxide is the only chemical added to the system, that could eliminate the complexity of iron-involved Fenton reactions or the use of the pulse-radiolysis system. PMID:19794928

  19. Glutathione--hydroxyl radical interaction: a theoretical study on radical recognition process.

    Directory of Open Access Journals (Sweden)

    Béla Fiser

    Full Text Available Non-reactive, comparative (2 × 1.2 μs molecular dynamics simulations were carried out to characterize the interactions between glutathione (GSH, host molecule and hydroxyl radical (OH(•, guest molecule. From this analysis, two distinct steps were identified in the recognition process of hydroxyl radical by glutathione: catching and steering, based on the interactions between the host-guest molecules. Over 78% of all interactions are related to the catching mechanism via complex formation between anionic carboxyl groups and the OH radical, hence both terminal residues of GSH serve as recognition sites. The glycine residue has an additional role in the recognition of OH radical, namely the steering. The flexibility of the Gly residue enables the formation of further interactions of other parts of glutathione (e.g. thiol, α- and β-carbons with the lone electron pair of the hydroxyl radical. Moreover, quantum chemical calculations were carried out on selected GSH/OH(• complexes and on appropriate GSH conformers to describe the energy profile of the recognition process. The relative enthalpy and the free energy changes of the radical recognition of the strongest complexes varied from -42.4 to -27.8 kJ/mol and from -21.3 to 9.8 kJ/mol, respectively. These complexes, containing two or more intermolecular interactions, would be the starting configurations for the hydrogen atom migration to quench the hydroxyl radical via different reaction channels.

  20. Living with endometriosis

    Science.gov (United States)

    Pelvic pain - living with endometriosis; Endometrial implant - living with endometriosis; Endometrioma - living with endometriosis ... counter pain relievers can reduce the pain of endometriosis. These include: Ibuprofen (Advil) Naproxen (Aleve) Acetaminophen (Tylenol) ...

  1. Active Solidarity: Centering the Demands and Vision of the Black Lives Matter Movement in Teacher Education

    Science.gov (United States)

    Mayorga, Edwin; Picower, Bree

    2018-01-01

    In the era of Black Lives Matter (#BLM), urban teacher education does not exist in isolation. The White supremacist, neoliberal context that impacts all aspects of Black lives also serves to support antiblackness within the structures of teacher education. In this article, the authors, who are grounded in a race radical analytical and political…

  2. p53 Mutagenesis by Benzo[a]pyrene derived Radical Cations

    Science.gov (United States)

    Sen, Sushmita; Bhojnagarwala, Pratik; Francey, Lauren; Lu, Ding; Jeffrey Field, Trevor M. Penning

    2013-01-01

    Benzo[a]pyrene (B[a]P), a major human carcinogen in combustion products such as cigarette smoke and diesel exhaust, is metabolically activated into DNA-reactive metabolites via three different enzymatic pathways. The pathways are the anti-(+)-benzo[a]pyrene 7,8-diol 9, 10-epoxide pathway (P450/ epoxide hydrolase catalyzed) (B[a]PDE), the benzo[a]pyrene o-quinone pathway (aldo ketose reductase (AKR) catalyzed) and the B[a]P radical cation pathway (P450 peroxidase catalyzed). We used a yeast p53 mutagenesis system to assess mutagenesis by B[a]P radical cations. Because radical cations are short-lived, they were generated in situ by reacting B[a]P with cumene hydroperoxide (CuOOH) and horse radish peroxidase (HRP) and then monitoring the generation of the more stable downstream products, B[a]P-1,6-dione and B[a]P-3,6-dione. Based on the B[a]P-1,6 and 3,6-dione formation, approximately 4µM of radical cation was generated. In the mutagenesis assays, the radical cations produced in situ showed a dose-dependent increase in mutagenicity from 0.25 µM to 10 µM B[a]P with no significant increase seen with further escalation to 50 µM B[a]P. However, mutagenesis was 200-fold less than with the AKR pathway derived B[a]P, 7–8 dione. Mutant p53 plasmids, which yield red colonies, were recovered from the yeast to study the pattern and spectrum of mutations. The mutation pattern observed was G to T (31%) > G to C (29%) > G to A (14%). The frequency of codons mutated by the B[a]P radical cations was essentially random and not enriched at known cancer hotspots. The quinone products of radical cations, B[a]P-1,6-dione and B[a]P-3,6-dione were more mutagenic than the radical cation reactions, but still less mutagenic than AKR derived B[a]P-7,8-dione. We conclude that B[a]P radical cations and their quinone products are weakly mutagenic in this yeast-based system compared to redox cycling PAH o-quinones. PMID:22768918

  3. Radical scavenging activity of crude polysaccharides from Camellia sinensis

    Directory of Open Access Journals (Sweden)

    Yang Fan

    2011-01-01

    Full Text Available A preparation of crude polysaccharides (TPS was isolated from Camellia sinensis by precipitation and ultrafiltration. TPS1, TPS2, and TPS3 had molecular weights of 240, 21.4, and 2.46 kDa, respectively. The radical scavenging activities of TPS were evaluated by DPPH free radical, hydroxyl radical and superoxide radical scavenging. These results revealed that TPS exhibited strong radical scavenging activity in a concentration-dependent manner. TPS3 with lowest molecular weight showed a higher radical scavenging activity.

  4. Understanding political radicalization: The two-pyramids model.

    Science.gov (United States)

    McCauley, Clark; Moskalenko, Sophia

    2017-04-01

    This article reviews some of the milestones of thinking about political radicalization, as scholars and security officials struggled after 9/11 to discern the precursors of terrorist violence. Recent criticism of the concept of radicalization has been recognized, leading to a 2-pyramids model that responds to the criticism by separating radicalization of opinion from radicalization of action. Security and research implications of the 2-pyramids model are briefly described, ending with a call for more attention to emotional experience in understanding both radicalization of opinion and radicalization of action. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  5. Can the United States Defeat Radical Islam

    Science.gov (United States)

    2008-05-22

    It strongly disapproves of idolatry, the popular cult of saints and tomb visitation. 11...twentieth century, Sayyid Qutb (1906-1966), an Egyptian Islamic radical, referencing al-Wahhab, developed a modified concept of jahiliyya. In Qutb’s...It strongly disapproves of idolatry, the popular cult of saints and tomb visitation. When ibn Taymiyya was asked if the murderous. Mongols, who

  6. Identity and Islamic Radicalization in Western Europe

    NARCIS (Netherlands)

    S.M. Murshed (Syed); S. Pavan (Sara)

    2009-01-01

    textabstractThis paper argues that both socio-economic disadvantage and political factors, such as the West’s foreign policy with regard to the Muslim world, along with historical grievances, play a part in the development of Islamic radicalized collective action in Western Europe. We emphasise the

  7. Lipophilic fluorescent products of free radicals

    Czech Academy of Sciences Publication Activity Database

    Ivica, Josko; Wilhelm, Jiří

    2014-01-01

    Roč. 158, č. 3 (2014), s. 365-372 ISSN 1213-8118 R&D Projects: GA ČR(CZ) GAP303/11/0298 Institutional support: RVO:67985823 Keywords : lipofuscin-like pigments * lipid peroxidation * free radical s * fluorescence Subject RIV: CE - Biochemistry Impact factor: 1.200, year: 2014

  8. Radical Negativity: Music Education for Social Justice

    Science.gov (United States)

    McLaren, Peter

    2011-01-01

    According to Hedges (2010), the real enemies of the liberal class are radical thinkers such as Noam Chomsky and Ralph Nader, iconoclastic intellectuals who possess the moral autonomy to defy the power elite. While this author agrees with Hedges, he would take this argument even further. In this article, the author argues that the real enemy of…

  9. Unimolecular reaction dynamics of free radicals

    International Nuclear Information System (INIS)

    Terry A. Miller

    2006-01-01

    Free radical reactions are of crucial importance in combustion and in atmospheric chemistry. Reliable theoretical models for predicting the rates and products of these reactions are required for modeling combustion and atmospheric chemistry systems. Unimolecular reactions frequently play a crucial role in determining final products. The dissociations of vinyl, CH2= CH, and methoxy, CH3O, have low barriers, about 13,000 cm-1 and 8,000 cm-1, respectively. Since barriers of this magnitude are typical of free radicals these molecules should serve as benchmarks for this important class of reactions. To achieve this goal, a detailed understanding of the vinyl and methoxy radicals is required. Results for dissociation dynamics of vinyl and selectively deuterated vinyl radical are reported. Significantly, H-atom scrambling is shown not to occur in this reaction. A large number of spectroscopic experiments for CH3O and CHD2O have been performed. Spectra recorded include laser induced fluorescence (LIF), laser excited dispersed fluorescence (LEDF), fluorescence dip infrared (FDIR) and stimulated emission pumping (SEP). Such results are critical for implementing dynamics experiments involving the dissociation of methoxy

  10. Neglected Side Effects After Radical Prostatectomy

    DEFF Research Database (Denmark)

    Frey, Anders Ullmann; Sønksen, Jens; Fode, Mikkel

    2014-01-01

    INTRODUCTION: A series of previously neglected sexually related side effects to radical prostatectomy (RP) has been identified over the recent years. These include orgasm-associated incontinence (OAI), urinary incontinence in relation to sexual stimulation (UISS), altered perception of orgasm, or...

  11. Letter: OCCO*+, NNCO*+ and NNNN*+ radical cations.

    Science.gov (United States)

    Flammang, R; Srinivas, R; Nguyen, M T; Gerbaux, P

    2007-01-01

    Chemical ionization of a mixture of nitrogen and carbon monoxide produces three stable isobaric species at m/z 56: OCCO, OCNN and NNNN radical cations. Separated at increased resolution, these ions are readily identified by collisional activation. Neutralization-reionization experiments performed on two different mass spectrometers have not allowed the detection of any recovery signals for the corresponding neutrals.

  12. Antioxidant Capacity, Radical Scavenging Kinetics and Phenolic ...

    African Journals Online (AJOL)

    Antioxidant Capacity, Radical Scavenging Kinetics and Phenolic Profile of Methanol Extracts of Wild Plants of Southern Sonora, Mexico. EF Moran-Palacio, LA Zamora-Álvarez, NA Stephens-Camacho, GA Yáñez- Farías, A Virgen-Ortiz, O Martínez-Cruz, JA Rosas-Rodríguez ...

  13. Quantification of Radicals Generated in a Sonicator

    Directory of Open Access Journals (Sweden)

    Kassim Badmus

    2016-06-01

    Full Text Available The hydroxyl radical (OH• is a powerful oxidant produced as a consequence of cavitation in water. It can react nonspecifically in breaking down persistent organic pollutants in water into their mineral form. It can also recombine to form hydrogen peroxide which is very useful in water treatment. In this study, terephthalic acid (TA and potassium iodide dosimetry were used to quantify and investigate the behaviour of the generated OH radical in a laboratory scale sonicator. The 2-hydroxyl terephthalic acid (HTA formed during terephthalic acid dosimetry was determined by optical fibre spectrometer. The production rate of HTA served as a means of evaluating and characterizing the OH• generated over given time in a sonicator. The influence of sonicator power intensity, solution pH and irradiation time upon OH• generation were investigated. Approximately 2.2 ´ 10-9 M s-1 of OH radical was generated during the sonication process. The rate of generation of the OH radicals was established to be independent of the concentration of the initial reactant. Thus, the rate of generation of OH• can be predicted by zero order kinetics in a sonicator.

  14. Parents’ Perspectives on Radicalization: A Qualitative Study

    NARCIS (Netherlands)

    E. Sikkens (Elga); M.R.P.J.R.S. van San (Marion); S. Sieckelinck (Stijn); M. de Winter (Micha)

    2018-01-01

    textabstractAbstract: Radicalization of young people might be influenced by the way parents react towards the development of political or religious ideals. However, these reactions have hardly been explored. This study aimed to discover how parents reacted to the development of extreme ideals, and

  15. Radical Feminism and the Subject of Writing.

    Science.gov (United States)

    Rhodes, Jacqueline

    The radical feminists of the late 1960s and early 1970s, as well as their online counterparts today, offer provocative examples of networked textuality, a discourse dependent on the constant and visible contextualization of self and writing within the discourses of hegemony. Given its potential use for liberatory writing pedagogies, it seems…

  16. Formation of radical cations of diaryloxadiazoles

    International Nuclear Information System (INIS)

    Helmstreit, W.

    1988-01-01

    The nature of the formation of the radical cation of the 2,5-bis-(p-diethylaminophenyl)-1,3,4-oxadiazole (PC) in liquid n-butyl chloride and acetonitrile has been investigated by observing excited state fluorescence and transient absorption using nanosecond pulse radiolysis and laser flash photolysis. The formation of solute oxonium ions has also been observed. At concentrations -4 mol dm -3 the growth time at which the transient absorption of the radical cation reaches the maximum follows the rise time of the electron pulse ( 2 laser yields the solute radical cation in an acetonitrile solution of 2 x 10 -4 mol dm -3 PC via an electronically excited state. Here, the generation time was smaller than 5 ns. The yield of the cation is increased by addition of CCl 4 . A reaction mechanism is proposed that explains the fast cation formation in terms of an exciplex formed by interaction between an electronically excited state of diaryloxadiazole and the ground state of the solvent. This exciplex yields the solute radical cation. (author)

  17. Albert Einstein: Radical Pacifist and Democrat

    Science.gov (United States)

    Jayaraman, T.

    We draw attention here to the radical political grounding of Einstein's pacifism. We also drescribe some less commonly known aspects of his commitment to civil liberties, particularly in the context of the anti-l hysteria and anti-racism current in the United States of the late 1940s and 1950s. We also examine briefly his views on socialism.

  18. Phytochemical screening, free radical scavenging and antibacterial ...

    African Journals Online (AJOL)

    Cassia sieberiana is a tropical plant, widely distributed throughout Sudan and Guinea savannah. It is used in traditional medicine for the treatment of malarial, cancer and stomach ache. The study was conducted to screen for phytochemicals, free radical scavenging and antibacterial potentials of the root bark.

  19. Radicals derived from acetaldehyde and vinyl alcohol.

    Science.gov (United States)

    Estep, Marissa L; Morgan, W James; Winkles, Alexander T; Abbott, Adam S; Villegas-Escobar, Nery; Mullinax, J Wayne; Turner, Walter E; Wang, Xiao; Turney, Justin M; Schaefer, Henry F

    2017-10-18

    Vinyl alcohol and acetaldehyde are isoelectronic products of incomplete butanol combustion. Along with the radicals resulting from the removal of atomic hydrogen or the hydroxyl radical, these species are studied here using ab initio methods as complete as coupled cluster theory with single, double, triple, and perturbative quadruple excitations [CCSDT(Q)], with basis sets as large as cc-pV5Z. The relative energies provided herein are further refined by including corrections for relativistic effects, the frozen core approximation, and the Born-Oppenheimer approximation. The effects of anharmonic zero-point vibrational energies are also treated. The syn conformer of vinyl alcohol is predicted to be lower in energy than the anti conformer by 1.1 kcal mol -1 . The alcoholic hydrogen of syn-vinyl alcohol is found to be the easiest to remove, requiring 84.4 kcal mol -1 . Five other radicals are also carefully considered, with four conformers investigated for the 1-hydroxyvinyl radical. Beyond energetics, we have conducted an overhaul of the spectroscopic literature for these species. Our results also provide predictions for fundamental modes yet to be reported experimentally. To our knowledge, the ν 3 (3076 cm -1 ) and ν 4 (2999 cm -1 ) C-H stretches for syn-vinyl alcohol and all but one of the vibrational modes for anti-vinyl alcohol (ν 1 -ν 14 ) are yet to be observed experimentally. For the acetyl radical, ν 6 (1035 cm -1 ), ν 11 (944 cm -1 ), ν 12 (97 cm -1 ), and accounting for our changes to the assignment of the 1419.9 cm -1 experimental mode, ν 10 (1441 cm -1 ), are yet to be observed. We have predicted these unobserved fundamentals and reassigned the experimental 1419.9 cm -1 frequency in the acetyl radical to ν 4 rather than to ν 10 . Our work also strongly supports reassignment of the ν 10 and ν 11 fundamentals of the vinoxy radical. We suggest that the bands assigned to the overtones of these fundamentals were in fact combination bands. Our

  20. Light ions and ozone - generation and interactions with living organisms

    International Nuclear Information System (INIS)

    Kriha, V.; Aubrecht, L.

    2005-01-01

    With directly in the living organism born ions exception, LNI coming through three phases: ionisation, attachment by the electronegative molecules and the clusters formation due to local electrostatic interactions. The quantitative analysis of physical parameters leads to conclusion that we cannot find any physical property (till known) explaining the positive affect of LNI on living organisms. Analysis of possible mechanism produces several hypotheses of LNI-organism interaction. A simplified semi-quantitative model of respiratory tract was developed for estimation of ions and ozone interaction with living organisms. A formation of oxygen radicals and products of their chain-reactions in intrinsic conditions is discussed

  1. Pertinent issues related to laparoscopic radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Sidney C. Abreu

    2003-12-01

    Full Text Available PURPOSE: We describe the critical steps of the laparoscopic radical prostatectomy (LRP technique and discuss how they impact upon the pertinent issues regarding prostate cancer surgery: blood loss, potency and continence. RESULTS: A major advantage of LRP is the reduced operative blood loss. The precise placement of the dorsal vein complex stitch associated with the tamponading effect of the CO2 pneumoperitoneum significantly decrease venous bleeding, which is the main source of blood loss during radical prostatectomy. At the Cleveland Clinic, the average blood loss of our first 100 patients was 322.5 ml, resulting in low transfusion rates. The continuous venous bleeding narrowed pelvic surgical field and poor visibility can adversely impact on nerve preservation during open radical prostatectomy. Laparoscopy, with its enhanced and magnified vision in a relatively bloodless field allows for excellent identification and handling of the neurovascular bundles. During open retropubic radical prostatectomy, the pubic bone may impair visibility and access to the urethral stump, and the surgeon must tie the knots relying on tactile sensation alone. Consequently, open prostatectomy is associated with a prolonged catheterization period of 2 - 3 weeks. Comparatively, during laparoscopic radical prostatectomy all sutures are meticulously placed and each is tied under complete visual control, resulting in a precise mucosa-to-mucosa approximation. CONCLUSION: The laparoscopic approach may represent a reliable less invasive alternative to the conventional open approach. Despite the encouraging preliminary anatomical and functional outcomes, prospective randomized comparative trials are required to critically evaluate the role of laparoscopy for this sophisticated and delicate operation.

  2. Multiple free-radical scavenging capacity in serum

    Science.gov (United States)

    Oowada, Shigeru; Endo, Nobuyuki; Kameya, Hiromi; Shimmei, Masashi; Kotake, Yashige

    2012-01-01

    We have developed a method to determine serum scavenging-capacity profile against multiple free radical species, namely hydroxyl radical, superoxide radical, alkoxyl radical, alkylperoxyl radical, alkyl radical, and singlet oxygen. This method was applied to a cohort of chronic kidney disease patients. Each free radical species was produced with a common experimental procedure; i.e., uv/visible-light photolysis of free-radical precursor/sensitizer. The decrease in free-radical concentration by the presence of serum was quantified with electron spin resonance spin trapping method, from which the scavenging capacity was calculated. There was a significant capacity change in the disease group (n = 45) as compared with the healthy control group (n = 30). The percent values of disease’s scavenging capacity with respect to control group indicated statistically significant differences in all free-radical species except alkylperoxyl radical, i.e., hydroxyl radical, 73 ± 12% (p = 0.001); superoxide radical, 158 ± 50% (p = 0.001); alkoxyl radical, 121 ± 30% (p = 0.005); alkylperoxyl radical, 123 ± 32% (p>0.1); alkyl radical, 26 ± 14% (p = 0.001); and singlet oxygen, 57 ± 18% (p = 0.001). The scavenging capacity profile was illustrated using a radar chart, clearly demonstrating the characteristic change in the disease group. Although the cause of the scavenging capacity change by the disease state is not completely understood, the profile of multiple radical scavenging capacities may become a useful diagnostic tool. PMID:22962529

  3. TRANSITION METAL CATALYSIS IN CONTROLLED RADICAL POLYMERIZATION: ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

    Science.gov (United States)

    Novel and diversified macromolecular structures, which include polymers with designed topologies (top), compostions (middle), and functionalities (bottom), can be prepared by atom transfer radical polymerization processes. These polymers can be synthesized from a large variety of...

  4. Triplet state and semiquinone free radical of 5-methoxyquinizarin : a laser flash photolysis and pulse radiolysis study

    International Nuclear Information System (INIS)

    Pal, H.; Patil, D.K.; Mukherjee, T.; Mittal, J.P.

    1992-01-01

    The triplet(T) state properties like T-T absorption spectra, quantum yield, energy level and decay kinetics of 5-methoxyquinizarin (5-methoxy-1, 4-dihydroxy-9, 10-anthraquinone; MQZ) have been investigated in cyclohexane, acetonitrile and isopropyl alcohol using nanosecond laser flash photolysis technique. In isopropylalcohol, a neutral semiquinone radical is also formed which has been characterised by comparing the long lived transient spectra with the MQZ-semiquinone spectra obtained by pulse radiolysis of MQZ in the same solvent. A relatively small amount of a long lived transient formed in cyclohexane and acetonitrile, along with the triplet state of MQZ, could not be characterised unambiguously, but has been attributed to the semiquinone radical of MQZ, produced by the reaction of the excited states of the quinone with the solvent. The quantum yield of the semiquinone radical in isopropyl alcohol is considerably higher than the triplet quantum yield, showing that both the excited singlet and the triplet states of the quinone probably react with the solvent molecules to form the semiquinone radical. The photophysical properties of the triplet and the semiquinone radical of MQZ have been compared with those of simple 1,4-disubstituted anthraquinones. (author). 23 refs., 5 figs., 1 tab

  5. Radical cations of quadricyclane and norbornadiene in polar ZSM-5 matrices: Radical cation photochemical transformations without photons

    International Nuclear Information System (INIS)

    Barnabas, M.V.; Trifunac, A.D.

    1994-01-01

    Radical cations of quadricyclane (Q) and norbornadiene (NBD) are produced by γ-radiolysis in zeolites. In polar ZSM-5, only one radical cation is initially observed below 100K. Increasing the temperature above 200K gives rise to the cyclopentadiene radical cation. Higher temperatures (>360K) give rise to the cyclopenten-4-yl radical. The observation of cyclopentadiene radical cation implies the occurrence of the reverse Diels-Alder reaction. This is a thermally forbidden, photochemically allowed, process, which is made possible by the interaction of the polar zeolite matrix sites with parent NBD and Q radical cations

  6. Developments in laser-induced fluorescence spectroscopy for quantitative in situ measurements of free radicals in the troposphere

    Science.gov (United States)

    Heard, Dwayne

    2015-04-01

    Photo-oxidation in the troposphere is highly complex, being initiated by short lived free radical species, in the daytime dominated by the hydroxyl radical, OH. Chemical oxidation cycles, which also involve peroxy radicals (HO2 and RO2), remove natural or anthropogenic emissions (for example methane) and generate a range of secondary products, for example ozone, nitrogen dioxide, acidic and multifunctional organic species, and secondary organic aerosol, which impact on human health and climate. Owing to their short lifetime in the atmosphere, the abundance of radicals is determined solely by their rate of chemical production and loss, and not by transport. Field measurements of the concentrations of radicals and comparison with calculations using a numerical model therefore constitutes one of the very best ways to test whether the chemistry in each of these locations is understood and accurately represented in the model. Validation of the chemistry is important, as the predictions of climate and air quality models containing this chemistry are used to drive the formulation of policy and legislation. However, in situ measurements of radical species, owing to their very low abundance (often sub part per trillion) and short lifetimes (pulse repetition rate tunable laser systems, will be discussed, together with calibration methods to make signals absolute, and identification of potential interferences. LIF instruments have been operated on ground, ship and aircraft platforms at a number of locations worldwide, and examples from recent fieldwork involving the Leeds instruments will be presented.

  7. Glutathione as a radical scavenger and the biological consequences of thiyl radical production

    International Nuclear Information System (INIS)

    Winterbourn, C.C.

    1996-01-01

    A large number of compounds that have toxic effects can be metabolised to free radicals and secondary reactive oxygen species. These may be directly damaging or affect cell function by altering regulatory mechanisms through changing redox status. Protection is provided by an integrated system of antioxidant defenses. This includes reduced glutathione (GSH), one of the functions of which is as a free radical scavenger. For GSH to be an effective radical scavenging antioxidant, therefore, it must act in concert with superoxide dismutase to remove the superoxide so generated. Superoxide is produced in a variety of metabolic processes. It is also a secondary product of radicals reacting with oxygen either directly or through GSH. The biological reactivity of superoxide has been the subject of much debate ever since the discovery of superoxide dismutase in 1968. It has more recently become apparent that its rapid reaction with nitric oxide to give peroxynitrite, and its ability to reversibly oxidise and inactivate iron sulphur enzymes, contribute to the toxicity of superoxide. Another mechanism that could be important involves addition reactions of superoxide with other radicals to give organic peroxides. This reaction, to form a tyrosine peroxide, has come to authors attention through the study of the scavenging of tyrosyl radicals by GSH. It is also shown that a tyrosine peroxide is a major product of the oxidation of tyrosine by neutrophils

  8. Radical surgery compared with intracavitary cesium followed by radical surgery in cervical carcinoma stage IB

    Energy Technology Data Exchange (ETDEWEB)

    Tinga, D.J.; Bouma, J.; Aalders, J.G. (Dept. of Obstetrics and Gynaecology, State Univ. Hospital, Groningen (Netherlands)); Hollema, H. (Dept. of Pathology, State Univ. Hospital, Groningen (Netherlands))

    1990-01-01

    Forty-nine patients aged {le} 45 years, with cervical carcinoma stage IB ({le} 3 cm) were treated with either primary radical surgery (n = 26), or intracavitary irradiation followed by radical surgery (n = 23). With primary surgery, ovarian function had been preserved in 15 of the 25 patients, who were alive and well. Seven of the primary surgery patients were irradiated postoperatively and 2 others with a central recurrence were cured by irradiation. One other patient, who was not irradiated postoperatively, had an intestinal metastasis and died of the disease. If any of the adverse prognostic factors (as reported in the literature) had been considered as an indication for postoperative irradiation, 17 patients instead of 7 would have been irradiated after primary radical surgery. In the comparable group of 23 patients treated by intracavitary irradiation and radical surgery (and in 4 cases postoperative irradiation as well) there was no recurrence. There was no significant statistical difference between the treatment results in the cesium + surgery group and those who underwent primary radical surgery. Young patients with early cervical carcinoma without prognostic indicators for postoperative irradiation can benefit from primary radical surgery, because their ovarian function can be preserved. (authors).

  9. Radical surgery compared with intracavitary cesium followed by radical surgery in cervical carcinoma stage IB

    International Nuclear Information System (INIS)

    Tinga, D.J.; Bouma, J.; Aalders, J.G.; Hollema, H.

    1990-01-01

    Forty-nine patients aged ≤ 45 years, with cervical carcinoma stage IB (≤ 3 cm) were treated with either primary radical surgery (n = 26), or intracavitary irradiation followed by radical surgery (n = 23). With primary surgery, ovarian function had been preserved in 15 of the 25 patients, who were alive and well. Seven of the primary surgery patients were irradiated postoperatively and 2 others with a central recurrence were cured by irradiation. One other patient, who was not irradiated postoperatively, had an intestinal metastasis and died of the disease. If any of the adverse prognostic factors (as reported in the literature) had been considered as an indication for postoperative irradiation, 17 patients instead of 7 would have been irradiated after primary radical surgery. In the comparable group of 23 patients treated by intracavitary irradiation and radical surgery (and in 4 cases postoperative irradiation as well) there was no recurrence. There was no significant statistical difference between the treatment results in the cesium + surgery group and those who underwent primary radical surgery. Young patients with early cervical carcinoma without prognostic indicators for postoperative irradiation can benefit from primary radical surgery, because their ovarian function can be preserved. (authors)

  10. Allergy, living and learning

    DEFF Research Database (Denmark)

    Chivato, T; Valovirta, E; Dahl, R

    2012-01-01

    Allergy Living and Learning (ALL) is a European initiative designed to increase knowledge and understanding of people living with allergies in order to improve respiratory allergy care.......Allergy Living and Learning (ALL) is a European initiative designed to increase knowledge and understanding of people living with allergies in order to improve respiratory allergy care....

  11. Pyrimidine nucleobase radical reactivity in DNA and RNA

    Science.gov (United States)

    Greenberg, Marc M.

    2016-11-01

    Nucleobase radicals are major products of the reactions between nucleic acids and hydroxyl radical, which is produced via the indirect effect of ionizing radiation. The nucleobase radicals also result from hydration of cation radicals that are produced via the direct effect of ionizing radiation. The role that nucleobase radicals play in strand scission has been investigated indirectly using ionizing radiation to generate them. More recently, the reactivity of nucleobase radicals resulting from formal hydrogen atom or hydroxyl radical addition to pyrimidines has been studied by independently generating the reactive intermediates via UV-photolysis of synthetic precursors. This approach has provided control over where the reactive intermediates are produced within biopolymers and facilitated studying their reactivity. The contributions to our understanding of pyrimidine nucleobase radical reactivity by this approach are summarized.

  12. Isoflurane preconditions myocardium against infarction via release of free radicals

    NARCIS (Netherlands)

    Müllenheim, Jost; Ebel, Dirk; Frässdorf, Jan; Preckel, Benedikt; Thämer, Volker; Schlack, Wolfgang

    2002-01-01

    BACKGROUND: Isoflurane exerts cardioprotective effects that mimic the ischemic preconditioning phenomenon. Generation of free radicals is implicated in ischemic preconditioning. The authors investigated whether isoflurane-induced preconditioning may involve release of free radicals. METHODS:

  13. Mechanism of protection of adenosine from sulphate radical anion ...

    Indian Academy of Sciences (India)

    Unknown

    Keywords. Repair by caffeic acid; repair of adenosine radicals; oxidation by sulphate radical anions. ... known that hydroxycinnamic acids are natural anti- oxidants ... acid. 2. Experimental ..... ously and independently under kinetic conditions at.

  14. Constructing Functional Ionic Membrane Surface by Electrochemically Mediated Atom Transfer Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Fen Ran

    2016-01-01

    Full Text Available The sodium polyacrylate (PAANa contained polyethersulfone membrane that was fabricated by preparation of PES-NH2 via nonsolvent phase separation method, the introduction of bromine groups as active sites by grafting α-Bromoisobutyryl bromide, and surface-initiated electrochemically atom transfer radical polymerization (SI-eATRP of sodium acrylate (AANa on the surface of PES membrane. The polymerization could be controlled by reaction condition, such as monomer concentration, electric potential, polymerization time, and modifier concentration. The membrane surface was uniform when the monomer concentration was 0.9 mol/L, the electric potential was −0.12 V, the polymerization time was 8 h, and the modifier concentration was 2 wt.%. The membrane showed excellent hydrophilicity and blood compatibility. The water contact angle decreased from 84° to 68° and activated partial thromboplastin increased from 51 s to 84 s after modification of the membranes.

  15. Surface modification of nanodiamond through metal free atom transfer radical polymerization

    Science.gov (United States)

    Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

    2016-12-01

    Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by 1H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

  16. Free Radical Scavenging Properties of Annona squamosa

    Science.gov (United States)

    Vikas, Biba; Akhil B, S; P, Remani; Sujathan, K

    2017-10-26

    Annona squamosa has extensively been used in the traditional and folkloric medicine and found to possess many biological activities. Different solvents, petroleum ether, chloroform, ethyl acetate and methanol extracts of Annona squamosa seeds (ASPE, ASCH, ASEA, ASME) have been used to prepare plant extracts. The present investigations dealt with the free radical scavenging activity of four extracts using various techniques such as total reducing power estimation, total phenolic count, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging effect, evaluation of ABTS cation decolorisation capacity, FRAP assay, hdroxyl radical scavenging assay, super oxide assay and Nitric oxide radical scavenging assay of the extracts. The results showed that the four extracts of Annona squamosa showed significant reducing power in four extracts. The total phenolic contents in petroleum ether, chloroform, ethyl acetate, methanol extracts and positive control were 0.64±0.17, 0.54±0.27, 0.49±0.24, 0.57±0.22 and 0.66±0.33. The antioxidant capacity by ABTS assay of ASPE, ASCH, ASEA, ASME and positive control, trolox showed 77.75±0.5,73.25±1.7,78.5± 1.2 , 80 ± 0.8 μg/ml and 94.2 ± 0.9 respectively. The (50 % scavenging activity) SA50 of ASPE and ASCH, ASEA and ASME was found to be 34.4 μg/ml, 43.8 μg/ml 34.7 μg/m and 28.8 μg/ml respectively by DPPH assay. The percentage of hydroxyl radical scavenging increased with the increasing concentration of the extracts. ASPE, ASCH, ASEA and ASME showed superoxide radical scavenging activity, as indicated by their values 66 ± 0.5, 68 ± 1 ,63 ± 1 and 70 ± 0.5 μg/ml respectively compared to gallic acid which was 97 ± 0.5 μg/ml. The values for scavenging of nitric oxide for ASPE, ASCH, ASEA and ASME were 91.0 ± 1.0, 66.75 ± 0.5, 71.75 ± 1.1 and 75.75 ± 1.15 μg/ml while value for standard ascorbic acid was 91.0 ± 1.0 μg/ml. The results revealed strong antioxidants in four extracts may lead to the development of potent

  17. Leadership Styles for the Five Stages of Radical Change

    Science.gov (United States)

    1998-04-01

    radical change. This article continues prior work on radical change with theory and research on leadership style. The result is a model of radical...every stage of that process. Leadership style and organiza- tional change theory and re- search have ex- isted for de- cades, but have rarely con...phase, inspire and en- ergize them to adopt the change after it Figure 3. Senior Manager Leadership Styles for the Five Phases of Radical Change Phase

  18. Superoxide radical (O2-) reactivity with respect to glutathione

    International Nuclear Information System (INIS)

    Sekaki, A.; Gardes-Albert, M.; Ferradini, C.

    1984-01-01

    Influence of superoxide radicals formed during gamma irradiation of glutathione in aerated aqueous solutions is examined. Solutions are buffered at pH7 and contain sodium formate for capture of H and OH radicals which are transformed in COO - radicals and then O 2 - radicals. G value of glutathione disparition vs glutathione concentration are given with and without enzyme or catalase. Reaction mechanism are interpreted [fr

  19. Tandem-robot assisted laparoscopic radical prostatectomy to improve the neurovascular bundle visualization: a feasibility study.

    Science.gov (United States)

    Han, Misop; Kim, Chunwoo; Mozer, Pierre; Schäfer, Felix; Badaan, Shadie; Vigaru, Bogdan; Tseng, Kenneth; Petrisor, Doru; Trock, Bruce; Stoianovici, Dan

    2011-02-01

    To examine the feasibility of image-guided navigation using transrectal ultrasound (TRUS) to visualize the neurovascular bundle (NVB) during robot-assisted laparoscopic radical prostatectomy (RALP). The preservation of the NVB during radical prostatectomy improves the postoperative recovery of sexual potency. The accompanying blood vessels in the NVB can serve as a macroscopic landmark to localize the microscopic cavernous nerves in the NVB. A novel, robotic transrectal ultrasound probe manipulator (TRUS Robot) and three-dimensional (3-D) reconstruction software were developed and used concurrently with the daVinci surgical robot (Intuitive Surgical, Inc., Sunnyvale, CA) in a tandem-robot assisted laparoscopic radical prostatectomy (T-RALP). After appropriate approval and informed consent were obtained, 3 subjects underwent T-RALP without associated complications. The TRUS Robot allowed a steady handling and remote manipulation of the TRUS probe during T-RALP. It also tracked the TRUS probe position accurately and allowed 3-D image reconstruction of the prostate and surrounding structures. Image navigation was performed by observing the tips of the daVinci surgical instruments in the live TRUS image. Blood vessels in the NVB were visualized using Doppler ultrasound. Intraoperative 3-D image-guided navigation in T-RALP is feasible. The use of TRUS during radical prostatectomy can potentially improve the visualization and preservation of the NVB. Further studies are needed to assess the clinical benefit of T-RALP. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Radical transfer between proteins: role of tyrosine, tryptophan and protein peroxyl radicals

    International Nuclear Information System (INIS)

    Irwin, J.A.; Ostdal, H.; Davies, M.J.

    1998-01-01

    Reaction of the Fe(III) forms of the heme proteins myoglobin (Mb) and horseradish peroxidase (HRP) with H 2 O 2 gives rise to high-oxidation-state heme-derived species which can be described as a Fe(IV)-oxo porphyrin radical-cation ('Compound 1'). In the case of Mb, the Fe(IV)-oxo porphyrin radical-cation undergoes rapid electron transfer with the surrounding protein to give protein (globin)-derived radicals and an Fe(lV)-oxo species ('Compound 2'). The globin-derived radicals have been shown to be located at two (or more) sites: Tyr-103 or Trp-14, with the latter radical known to react with oxygen to give a Trp-derived peroxyl radical (Mb-Trp-OO*). With HRP, the Fe(lV)-oxo porphyrin radical-cation carries out two successive one-electron oxidation reactions at the exposed heme edge to give firstly 'Compound 2' [the Fe(lV)oxo species] and then the resting Fe(III) state of the enzyme. n this study we have investigated whether the Trp-14 peroxyl radical from Mb and the Compound 1 and 2 species from HRP (in the absence and presence of free Tyr) can oxidise amino acids, peptides and proteins. Such reactions constitute intermolecular protein-to-protein radical transfer reactions and hence protein chain-oxidation. We have also examined whether these oxidants react with antioxidants. Reaction of these heme-protein derived oxidants with amino acids, proteins and antioxidants has been carried out at room temperature for defined periods of time before freeze-quenching to 77K to halt reaction. The radical species present in the reaction system at the time of freezing were subsequently examined by EPR spectroscopy at 77K. Three free amino acids, Tyr, Trp and Cys (with Cys the least efficient) have been shown to react rapidly with Mb-Trp-OO*, as evidenced by the loss of the characteristic EPR features of Mb-Trp-OO* on inclusion of increasing concentrations of the amino acids. All other amino acids are much less reactive. Evidence has also been obtained for (inefficient) hydrogen

  1. Hybrid radical energy storage device and method of making

    Science.gov (United States)

    Gennett, Thomas; Ginley, David S; Braunecker, Wade; Ban, Chunmei; Owczarczyk, Zbyslaw

    2015-01-27

    Hybrid radical energy storage devices, such as batteries or electrochemical devices, and methods of use and making are disclosed. Also described herein are electrodes and electrolytes useful in energy storage devices, for example, radical polymer cathode materials and electrolytes for use in organic radical batteries.

  2. Responsibility for radical change in addressing climate change

    NARCIS (Netherlands)

    Bouvrie, des N.; Karlsson-Vinkhuyzen, S.I.S.E.; Jollands, N.

    2015-01-01

    To radically address the problem of climate change, it is not enough to modify specific attitudes and behaviors while upholding the present paradigms. This article aims to show why modifications will never bring about radical carbon emission reductions. We discuss what it implies to desire radical

  3. Biochemistry and pathology of radical-mediated protein oxidation

    DEFF Research Database (Denmark)

    Dean, R T; Fu, S; Stocker, R

    1997-01-01

    Radical-mediated damage to proteins may be initiated by electron leakage, metal-ion-dependent reactions and autoxidation of lipids and sugars. The consequent protein oxidation is O2-dependent, and involves several propagating radicals, notably alkoxyl radicals. Its products include several catego...

  4. Enhancing production through optimisation of DPPH and radical ...

    African Journals Online (AJOL)

    ... of dry matter for DPPH radical scavenging activity. Methanol had the lowest value (78 mg g-1 dry matter) for polyphenol extracts and 80 mg g-1 for the DPPH radical scavenging activity. The main extract compounds were gallic acid, catechin and epicatechin. Key Words: High density lipids, polyphenol, radical scavenging ...

  5. Radical radiotherapy for T3 laryngeal cancers

    International Nuclear Information System (INIS)

    Uno, T.; Itami, J.; Kotaka, K.; Toriyama, M.

    1996-01-01

    From 1974 through 1992, 37 previously untreated patients with T3 laryngeal cancer (supraglottic 15, glottic 22) were treated with initial radical radiotherapy and surgery for salvage. Two-year local control rate with radiotherapy alone, ultimate voice preservation rate, and ultimate local control rate for T3 supraglottic cancer were 33%, 33%, and 60%, respectively. Corresponding figures for T3 glottic cancer were 32%, 23%, and 77%, respecitvely. Five-year cause-specific survival rate for T3 supraglottic cancer and glottic cancer were 47% and 77%, respectively. In T3 supraglottic cancer, none of the 4 patients with subglottic tumor extension attained local control by radiotherapy alone, and local-regional recurrence-free time were significantly shorter in patients with subglottic tumor extension or tracheostomy before radiotherapy. There were no serious late complications such as chondronecrosis, rupture of carotid artery attributed to radical radiotherapy, while 3 patients had severe laryngeal edema requiring total laryngectomy. (orig.) [de

  6. Editorial: RADICALISM AND POLITICS OF RELIGION

    Directory of Open Access Journals (Sweden)

    Editorial Al-Jami'ah: Journal of Islamic Studies

    2008-02-01

    Full Text Available Radical Islamism has become the “sexiest” issue in the international scholarship of religion since the September 11 tragedy in 2001. It has been associated with a number of terrorist attacks not only in the West but also in Muslim countries. Every single of radical Islamism has caught the interest of not only scholars and policy makers but also general public. Interestingly, the general assumption that religion is the source of peace has been seriously challenged, not by non-religious communities, but by the violent practices of particular religious groups, however small they are. Indeed, there are certain groups striving for Islam but by using acts which could give awful image on Islam itself and against humanity.

  7. Freedom Now! Radical Jazz and Social Movements

    Directory of Open Access Journals (Sweden)

    Przemysław Pluciński

    2014-01-01

    Full Text Available Music is obviously not only an aesthetic phenomenon. It is embeddedin a dense network of social relations. However, its social involvementis rather ambiguous, particularly since the second half of the twentiethcentury. On the one hand, music is one of the main elements of culturalcapitalism and a part of the system of domination. On the other hand,music provokes, (coproduces or possibly strengthens and coexists witha number of counterdiscourses and social projects of counterhegemoniccharacter.The main objective of the paper is to examine relationships between both, revolutionary jazz and revolutionary social movements, namely the civil rights movement, but above all radical movements, especially black power movement. The crucial questions I am interested in are problems of selforganization, performative social practices, as well as alternatives elaborated by radical-oriented jazz circles in various social dimensions, for instance economic or symbolic.

  8. Electronic spectrum of 9-methylanthracenium radical cation

    Energy Technology Data Exchange (ETDEWEB)

    O’Connor, Gerard D.; Schmidt, Timothy W., E-mail: timothy.schmidt@unsw.edu.au [School of Chemistry, UNSW Sydney, New South Wales 2052 (Australia); Sanelli, Julian A.; Dryza, Vik; Bieske, Evan J. [School of Chemistry, The University of Melbourne, Victoria 3010 (Australia)

    2016-04-21

    The predissociation spectrum of the cold, argon-tagged, 9-methylanthracenium radical cation is reported from 8000 cm{sup −1} to 44 500 cm{sup −1}. The reported spectrum contains bands corresponding to at least eight electronic transitions ranging from the near infrared to the ultraviolet. These electronic transitions are assigned through comparison with ab initio energies and intensities. The infrared D{sub 1}←D{sub 0} transitions exhibit significant vibronic activity, which is assigned through comparison with TD-B3LYP excited state frequencies and intensities, as well as modelled vibronic interactions. Dissociation of 9-methylanthracenium is also observed at high visible-photon energies, resulting in the loss of either CH{sub 2} or CH{sub 3}. The relevance of these spectra, and the spectra of other polycyclic aromatic hydrocarbon radical cations, to the largely unassigned diffuse interstellar bands, is discussed.

  9. Peace journalism and radical media ethics

    Directory of Open Access Journals (Sweden)

    Marta Natalia Lukacovic

    2016-10-01

    Full Text Available The radical characteristics of peace journalism position it as a model that expands the current understandings of normative media theory. Peace journalism echoes the most innovative calls of media ethicists, such as the proposition of radical media ethics. This idea asserts the necessity to expand media ethics to better fit the globalized and democratized media landscape, which is enabled by contemporary new media technologies. Essentially a global shift, among professionals as well as regular citizen-communicators, should advance towards conflict sensitivity in order to transcend the culturally violent elements of covering conflicts. Similar efforts will bring numerous challenges, however, these efforts are tremendously worthwhile with their potential to assist the creation of more peace-prone global societies.

  10. Radical pancreatectomy: postoperative evaluation by CT

    Energy Technology Data Exchange (ETDEWEB)

    Heiken, J.P.; Balfe, D.M.; Picus, D.; Scharp, D.W.

    1984-10-01

    Twenty-four patients who had undergone radical pancreatic resection were evaluated by CT one week to 11 years after surgery. Eighteen patients had had the Whipple procedure; six had had total pancreatectomy. The region between the aorta and superior mesenteric artery, previously occupied by the uncinate process of the pancreas, is an important area to evaluate for tumor recurrence because periampullary tumors tend to metastasize to the lymph nodes in this region. Tumor recurrence here is readily detectable by CT since radical pancreatectomy leaves this area area free of soft tissue attenuation material. CT demonstrated postoperative complications or tumor recurrence in 16 of the 24 patients and was 100% accurate in patients who had follow-up.

  11. International Radical Cystectomy Consortium: A way forward

    Directory of Open Access Journals (Sweden)

    Syed Johar Raza

    2014-01-01

    Full Text Available Robot-assisted radical cystectomy (RARC is an emerging operative alternative to open surgery for the management of invasive bladder cancer. Studies from single institutions provide limited data due to the small number of patients. In order to better understand the related outcomes, a world-wide consortium was established in 2006 of patients undergoing RARC, called the International Robotic Cystectomy Consortium (IRCC. Thus far, the IRCC has reported its findings on various areas of operative interest and continues to expand its capacity to include other operative modalities and transform it into the International Radical Cystectomy Consortium. This article summarizes the findings of the IRCC and highlights the future direction of the consortium.

  12. Coming to Grips with Radical Social Constructivisms

    Science.gov (United States)

    Phillips, D. C.

    This essay distinguishes two broad groups - psychological constructivists and social constructivists - but focusses upon the second of these, although it is stressed that there is great within group variation. More than half of the paper is devoted to general clearing of the ground, during which the reasons for the growing acrimony in the debates between social constructivists and their opponents are assessed, an important consequence of these debates for education is discussed, and an examination is carried out of the radical social constructivist tendency to make strong and exciting but untenable claims which are then backed away from (a tendency which is documented by a close reading of the early pages in Bloors classic book). The last portion of the essay focuses upon social constructivist accounts of the causes of belief in science - the more radical of which denegrate the role of warranting reasons, and which give an exalted place to quasi-anthropological or sociological studies of scientific communities.

  13. Radical pancreatectomy: postoperative evaluation by CT

    International Nuclear Information System (INIS)

    Heiken, J.P.; Balfe, D.M.; Picus, D.; Scharp, D.W.

    1984-01-01

    Twenty-four patients who had undergone radical pancreatic resection were evaluated by CT one week to 11 years after surgery. Eighteen patients had had the Whipple procedure; six had had total pancreatectomy. The region between the aorta and superior mesenteric artery, previously occupied by the uncinate process of the pancreas, is an important area to evaluate for tumor recurrence because periampullary tumors tend to metastasize to the lymph nodes in this region. Tumor recurrence here is readily detectable by CT since radical pancreatectomy leaves this area area free of soft tissue attenuation material. CT demonstrated postoperative complications or tumor recurrence in 16 of the 24 patients and was 100% accurate in patients who had follow-up

  14. EPR study of free radicals in bread

    Science.gov (United States)

    Yordanov, Nicola D.; Mladenova, Ralitsa

    2004-05-01

    The features of the recorded EPR spectra of paramagnetic species formed in bread and rusk are reported. The appearance of free radicals in them is only connected with their thermal treatment since the starting materials (flour and grains) exhibit very weak EPR signal. The obtained EPR spectra are complex and indicate that: (i) the relative number of paramagnetic species depends on the temperature and treating time of the raw product; (ii) the g-values are strongly temperature dependent with a tendency to coincide at t≥220 °C. Because of the relatively low (150-220 °C) temperature of thermal treatment, the studied free radicals can be assumed to appear in the course of the browning (Maillard) reaction and not to the carbonization of the material.

  15. Oxidation of Cu(II) aminopolycarboxylates by carbonate radical. A flash photolysis study

    International Nuclear Information System (INIS)

    Mandal, P.C.; Bardhan, D.K.

    1999-01-01

    Reactions of carbonate radical (CO 3 -. ) generated by photolysis or by radiolysis of a carbonate solution, with Cu(II) complexes of aminopolycarboxylic acids viz., Cu(II)ethylenediamine tetraacetate [Cu II EDTA] 2- and Cu(II)-iminodiacetate [Cu II IDA] were studied at pH 10.5 and ionic strength 0.2 mol x dm -3 . Time-resolved spectroscopy and kinetics for the transients were studied using flash photolysis and stable products arising from the ligand degradation of the complex were ascertained by steady-state radiolysis experiments. From the kinetic data it is observed that CO 3 -. radical reacts initially with Cu II -complex to form a transient intermediate having maximum absorption at 335 nm and 430 nm. From the subsequent reactions of this intermediate it was assigned to be Cu III .species. This Cu(III) species undergoes intermolecular electron transfer with the Cu II -complex to give a radical intermediate which again slowly reacts with Cu II -complex to give a long lived species containing Cu-C bond. This long lived species, however, slowly decomposed to give glyoxalic reaction between Cu III -complex and a suitable donor, the one electron reduction potential for [Cu III EDTA] 1- /[Cu II EDTA] 2- and [Cu III IDA] +1 /Cu II IDA was determined. (author)

  16. EARLY POSTOPERATIVE COMPLICATIONS AFTER RADICAL CYSTECTOMY

    Directory of Open Access Journals (Sweden)

    V. O. Mager

    2014-08-01

    Full Text Available Radical cystectomy (RCE is associated with a considerable number of early postoperative complications as before. Based on 10 years’ experience, this paper demonstrates the frequency (33.9 % and types of early complications following RCE, as well as postoperative mortality (5.5 % and its resulting causes. Although postoperative mortality is relatively low today, the frequency of early postoperative complications remains high as before.

  17. Hydroxyl free radical production during torsional phacoemulsification.

    Science.gov (United States)

    Aust, Steven D; Hebdon, Thomas; Humbert, Jordan; Dimalanta, Ramon

    2010-12-01

    To quantitate free radical generation during phacoemulsification using an ultrasonic phacoemulsification device that includes a torsional mode and evaluate tip designs specific to the torsional mode. Chemistry and Biochemistry Department, Utah State University, Logan, Utah, USA. Experimental study. Experiments were performed using the Infiniti Vision System and OZil handpiece. Hydroxyl radical concentrations in the aspirated irrigation solution during torsional phacoemulsification were quantitated as nanomolar malondialdehyde (nM MDA) and determined spectrophotometrically using the deoxyribose assay. The mean free radical production during phacoemulsification with torsional modality at 100% amplitude was 30.1 nM MDA ± 5.1 (SD) using a 0.9 mm 45-degree Kelman tapered ABS tip. With other tip designs intended for use with the torsional modality, free radical production was further reduced when fitted with the 0.9 mm 45-degree Kelman mini-flared ABS tip (13.2 ± 5.6 nM MDA) or the 0.9 mm 45-degree OZil-12 mini-flared ABS tip (14.3 ± 6.7 nM MDA). Although the measurements resulting from the use of the latter 2 tips were not statistically significantly different (P ≈ .25), they were different from those of the tapered tip (P<.0001). The MDA concentration in the aspirated irrigation solution using the torsional modality was approximately one half that reported for the handpiece's longitudinal modality in a previous study using the same bent-tip design (Kelman tapered, P<.0001). The level of MDA was further reduced approximately one half with torsional-specific tips. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  18. How Hume's Philosophy Informed Radical Behaviorism.

    Science.gov (United States)

    Nuzzolilli, Andrew E; Diller, James W

    2015-05-01

    The present paper analyzes consistencies between the philosophical systems of David Hume and B. F. Skinner, focusing on their conceptualization of causality and attitudes about scientific behavior. The ideas that Hume initially advanced were further developed in Skinner's writings and shaped the behavior-analytic approach to scientific behavior. Tracing Skinner's logical antecedents allows for additional historical and philosophical clarity when examining the development of radical behaviorism.

  19. Western Radicalization: Rethinking the Psychology of Terrorism

    Science.gov (United States)

    2017-03-01

    to do so, they assert, locks both the researcher and the research subject into a “spiral of ignorance and suspicion.” Moreover, “social identity ...percentage of firefighters who commit this type of arson do so to establish an identity and sense of belonging. Similarly, disconnected Westerners...percentage of firefighters who commit this type of arson do so to establish an identity and sense of belonging. Similarly, disconnected Westerners radicalize

  20. Computed tomography after radical pancreaticoduodenectomy (Whipple's procedure)

    International Nuclear Information System (INIS)

    Smith, S.L.; Hampson, F.; Duxbury, M.; Rae, D.M.; Sinclair, M.T.

    2008-01-01

    Whipple's procedure (radical pancreaticoduodenectomy) is currently the only curative option for patients with periampullary malignancy. The surgery is highly complex and involves multiple anastomoses. Complications are common and can lead to significant postoperative morbidity. Early detection and treatment of complications is vital, and high-quality multidetector computed tomography (MDCT) is currently the best method of investigation. This review outlines the surgical technique and illustrates the range of normal postoperative appearances together with the common complications

  1. Radicalization as a Vector: Exploring Non-Violent and Benevolent Processes of Radicalization.

    Directory of Open Access Journals (Sweden)

    Ken Reidy

    2018-03-01

    Full Text Available Successful radicalization posits three outcomes: extremism, terrorism or both. As these are undesirable, radicalization is understood as wholly malevolent and governments work to prevent and/or stop it. Nonetheless, a handful of scholars have recognized that the same radicalization process which results in either outcome may, theoretically at least, also have beneficial outcomes such as environmental awareness or human rights. This article explores one such outcome. Based on interviews with British Muslim aid workers (n=6 operating in Jihadist conflict zones post Arab spring and using constructivist grounded theory, it illustrates how the research participants radicalized to humanitarianism which resulted in them assisting the most plighted of Muslims by deploying to the most wanton of areas: ones commonly referred to as Jihadist conflict zones. Evidently, these destinations are shared with Jihadists and given the array of other observable similarities (socio-demographics and [pre-]mobilization behaviours, these morally opposed groups become conflated by the security services. This is further compounded by the fact that Jihadists manipulate and/or impersonate aid workers so as to funnel people and funds. To distinguish both, this article documents the benevolent pathway of the research participants and juxtaposes it to scholarly knowledge on Jihadist pathways. Socialization was revealed to be the key distinguishing feature rather than descriptive risk factors (such as ideology or moral outrage because the process of radicalization was not found to be the start of the radicalized pathway. It concludes that benevolently radicalized Islamic groups constitute an effective means of pathway divergence for particular typologies by offering an attractive and prosocial alternative to Jihadism. This strengths-based preventative approach (“what’s right” takes the form of a community-centric market competitor to Jihadism rather than a problem

  2. Free radicals induced archive paper by irradiation

    International Nuclear Information System (INIS)

    Cutrubinis, M.; Moise, I.V.; Negut, C.D.; Georgescu, R.; Suvaila, R.; Virgolici, M.; Manea, M.M.

    2011-01-01

    Complete text of publication follows. Irradiation of archive paper (document archives of institutions, companies etc. and library or museum collections of books and documents) can solve the problems related to the bio-deterioration and bio-contamination of paper and sometimes save valuable cultural heritage paper items. For valuable paper items care should be taken to the degradation induced instantly by the ionising radiation to the cellulosic support and also to the long term post-irradiation effects. The free radicals formed due to the irradiation treatment could contribute to instant degradation of paper. Part of them are also trapped for months and years after irradiation and they could be related to the post-irradiation effects in paper items. In this study, different sorts of cellulosic support samples (soft wood and hard wood cellulose, contemporary paper, paper from archives and from collections etc.) have been irradiated with dosis up to 100 kGy and the radiation induced free radicals have been measured by ESR spectrometry. The ESR signals have shown the type and quantity of radiation induced free radicals. Their study can be used for a realistic estimation of the degradative effect of the ionising radiation treatment of archive paper.

  3. Complications of Radical Cystectomy and Orthotopic Reconstruction

    Directory of Open Access Journals (Sweden)

    Wei Shen Tan

    2015-01-01

    Full Text Available Radical cystectomy and orthotopic reconstruction significant morbidity and mortality despite advances in minimal invasive and robotic technology. In this review, we will discuss early and late complications, as well as describe efforts to minimize morbidity and mortality, with a focus on ileal orthotopic bladder substitute (OBS. We summarise efforts to minimize morbidity and mortality including enhanced recovery as well as early and late complications seen after radical cystectomy and OBS. Centralisation of complex cancer services in the UK has led to a fall in mortality and high volume institutions have a significantly lower rate of 30-day mortality compared to low volume institutions. Enhanced recovery pathways have resulted in shorter length of hospital stay and potentially a reduction in morbidity. Early complications of radical cystectomy occur as a direct result of the surgery itself while late complications, which can occur even after 10 years after surgery, are due to urinary diversion. OBS represents the ideal urinary diversion for patients without contraindications. However, all patients with OBS should have regular long term follow-up for oncological surveillance and to identify complications should they arise.

  4. Radical Homemaking in Contemporary American Environmental Fiction

    Directory of Open Access Journals (Sweden)

    Kristin J. Jacobson

    2018-02-01

    Full Text Available Ursula K. Heise in ‘Ecocriticism and the Transnational Turn in American Studies’ critiques ‘the portrayal of multicultural and sometimes transnational nuclear families as the narrative solution to environmental and political problems’ (Heise, 2008: 383. This essay places Heise’s critique of the ‘ecological family romance’ in conversation with three other ecological domestic fictions: T. C. Boyle’s 'A Friend of the Earth' (2000, Jonathan Franzen’s 'Freedom' (2010, and Barbara Kingsolver’s 'Flight Behavior' (2012. Heise’s critique and Shannon Hayes’ 'Radical Homemakers' (2010 frame my close readings of the novels’ interconnected themes of radical homemaking, transnationalism, and environmentalism. My reading of the novels highlights their shared use of marginalized, racially-other characters to develop their entwined romantic and environmental plots (Lalitha in 'Freedom', several minor characters in 'A Friend of the Earth', and Ovid in 'Flight Behavior' and their use of sentimental deaths, especially of key female characters (Lalitha in Freedom, Sierra in A Friend of the Earth, and Dellarobia’s uncertain fate in Flight Behavior. By adopting the sentimental, domestic romance plot for ecological aims, the three novels highlight how environmental aims get stymied when cultural and ecological diversity are relegated to the margins. They also suggest that more is gained than lost through their use of ecological allegory. While the fictions do not offer solutions, they do push their readers to confront the Anthropocene’s ecological realities and their radical domestic-environmental politics.

  5. The Rise of Radicals in Bioinorganic Chemistry.

    Science.gov (United States)

    Gray, Harry B; Winkler, Jay R

    2016-10-01

    Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O 2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) and tryptophan (Trp) residues have been found in many O 2 -reactive enzymes, raising the possibility that they play an antioxidant protective role. In blue copper proteins with plastocyanin-like domains, Tyr/Trp clusters are uncommon in the low-potential single-domain electron-transfer proteins and in the two-domain copper nitrite reductases. The two-domain muticopper oxidases, however, exhibit clusters of Tyr and Trp residues near the trinuclear copper active site where O 2 is reduced. These clusters may play a protective role to ensure that reactive oxygen species are not liberated during O 2 reduction.

  6. Peroxy Radical Measurements via Laser Induced Fluorescence

    Science.gov (United States)

    Trawny, Katrin; Tatum Ernest, Cheryl; Novelli, Anna; Elste, Thomas; Plaß-Dülmer, Christian; Rudolf, Markus; Martinez, Monica; Harder, Hartwig; Lelieveld, Jos

    2013-04-01

    We present a newly built Laser Induced Fluorescence (LIF) system to measure the sum of all peroxy radicals (RO2) utilizing chemical conversion to OH. This instrument operates in two different modes: the ROx mode (sum of OH, HO2, and RO2) and the HOx mode (sum of OH and HO2). The HOx mode is used to derive the RO2 data from the ROx measurements. A model approach was used during instrumental development to identify the key parameters needed for the conversion process in front of the detection area and to optimize sensitivity. The instrument was then carefully characterized in various lab experiments, where it could be shown that the wall losses for HO2 are negligible and that nearly all HO2 is converted to OH in front of the detection zone. The pressure and temperature dependencies were also analyzed and assured that the instrument does not show any photolytical interference. As the instrument is calibrated with only one kind of peroxy radicals it was very important that the differences in sensitivity for different peroxy radicals are acceptable. Lab experiments as well as first results from the HOPE 2012 intensive field campaign, which took place in summer 2012 at the Global Atmosphere Watch (GAW) station of the German Weather Service, will be discussed.

  7. Laparoscopic radical prostatectomy in the canine model.

    Science.gov (United States)

    Price, D T; Chari, R S; Neighbors, J D; Eubanks, S; Schuessler, W W; Preminger, G M

    1996-12-01

    The purpose of this study was to determine the feasibility of performing laparoscopic radical prostatectomy in a canine model. Laparoscopic radical prostatectomy was performed on six adult male canines. A new endoscopic needle driver was used to construct a secure vesicourethral anastomosis. Average operative time required to complete the procedure was 304 min (range 270-345 min). Dissection of the prostate gland took an average of 67 min (range 35-90 min), and construction of the vesicourethral anastomosis took 154 min (rage 80-240 min). There were no intraoperative complications and only one postoperative complication (anastomotic leak). Five of the six animals recovered uneventfully from the procedure, and their foley catheters were removed 10-14 days postoperatively after a retrograde cystourethrogram demonstrated an intact vesicourethral anastomosis. Four (80%) of the surviving animals were clinically continent within 10 days after catheter removal. Post mortem examination confirmed that the vesicourethral anastomosis was intact with no evidence of urine extravasation. These data demonstrate the feasibility of laparoscopic radical prostatectomy in a canine model, and suggest that additional work with this technique should be continued to develop its potential clinical application.

  8. Radical inactivation of a biological sulphydryl molecule

    International Nuclear Information System (INIS)

    Lin, W.S.; Lal, M.; Gaucher, G.M.; Armstrong, D.A.

    1977-01-01

    Reactive species produced from the free radical-induced chain oxidation of low molecular weight sulphydryl-containing molecules in aerated solutions deactivate the sulphydryl-containing enzyme papain, forming both reparable mixed disulphides and non-reparable products. This inactivation is highly efficient for penicillamine and glutathione, but almost negligible with cysteine, which is a protector of papain for [cysteine] / [papain] >= 5 under all conditions used. In the case of glutathione, superoxide dismutase caused only a small reduction in the inactivation and peroxide yields were small, implying that the deactivating species are not .O 2 - but RSOO. radicals or products from them. For penicillamine, however, dimutase was highly effective and the peroxide yields were relatively large, demonstrating that .O 2 - or a radical with similar capabilities for forming H 2 O 2 and being deactivated by dismutase was involved. Although in the presence of dismutase penicillamine is a better protector of non-reparable papain inactivation than glutathione, it suffers from a deficiency in that the papain-penicillamine mixed disulphide, which is always formed, cannot be repaired by spontaneous reaction with RSH molecules. (author)

  9. Orthographic Skills Important to Chinese Literacy Development: The Role of Radical Representation and Orthographic Memory of Radicals

    Science.gov (United States)

    Yeung, Pui-sze; Ho, Connie Suk-han; Chan, David Wai-ock; Chung, Kevin Kien-hoa

    2016-01-01

    A 3-year longitudinal study among 239 Chinese students in Grades 2-4 was conducted to investigate the relationships between orthographic skills (including positional and functional knowledge of semantic radicals and phonetic radicals, and orthographic memory of radicals) and Chinese literacy skills (word reading, word spelling, reading…

  10. Generation and propagation of radical reactions on proteins

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    2001-01-01

    The oxidation of proteins by free radicals is thought to play a major role in many oxidative processes within cells and is implicated in a number of human diseases as well as ageing. This review summarises information on the formation of radicals on peptides and proteins and how radical damage may...... be propagated and transferred within protein structures. The emphasis of this article is primarily on the deleterious actions of radicals generated on proteins, and their mechanisms of action, rather than on enzymatic systems where radicals are deliberately formed as transient intermediates. The final section...

  11. Formation and spectroscopy of {alpha}-muoniated radicals

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, I.; Brodovitch, J.C.; Ghandi, K.; Kecman, S.; Percival, P.W

    2003-02-01

    Several novel {alpha}-muoniated radicals have been produced by the reaction of muonium with compounds containing diazo, isocyanate or carbene functional groups. In {alpha}-muoniated radicals the muon is attached directly to the radical centre; they can be formed either directly or indirectly via a {beta}-muoniated radical intermediate. The hyperfine coupling constants of the resulting radicals have been measured by transverse field muon spin rotation and muon avoided level-crossing resonance. The effect of muonium substitution was investigated for cases where ESR data are available for comparison.

  12. Formation and spectroscopy of α-muoniated radicals

    International Nuclear Information System (INIS)

    McKenzie, I.; Brodovitch, J.C.; Ghandi, K.; Kecman, S.; Percival, P.W.

    2003-01-01

    Several novel α-muoniated radicals have been produced by the reaction of muonium with compounds containing diazo, isocyanate or carbene functional groups. In α-muoniated radicals the muon is attached directly to the radical centre; they can be formed either directly or indirectly via a β-muoniated radical intermediate. The hyperfine coupling constants of the resulting radicals have been measured by transverse field muon spin rotation and muon avoided level-crossing resonance. The effect of muonium substitution was investigated for cases where ESR data are available for comparison

  13. Reactions of melatonin with radicals in deoxygenated aqueous solution

    International Nuclear Information System (INIS)

    Stasica, P.; Ulanski, P.; Rosiak, J.M.

    1998-01-01

    Reactions of melatonin (N-acetyl-5-methoxytryptamine) with radiolytically generated radicals were studied. Reaction of melatonin with OH radicals is diffusion-controlled (k=1.2 x 10 10 dm 3 mol -1 x s -1 ), the main (but not the only one) intermediate being the indolyl-type radical, while the rate constant for the reaction with hydrated electrons is k=4.3 x 10 8 dm 3 x mol -1 x s -1 . Melatonin is capable of scavenging tert-butanol radicals, while its reactivity towards polymer radicals of poly(acrylic acid) and poly(vinyl pyrrolidone) is very low. (author)

  14. What is Radical Behaviorism? A Review of Jay Moore's Conceptual Foundations of Radical Behaviorism

    Science.gov (United States)

    Baum, William M

    2011-01-01

    B. F. Skinner founded both radical behaviorism and behavior analysis. His founding innovations included: a versatile preparation for studying behavior; explicating the generic nature of stimulus and response; a pragmatic criterion for defining behavioral units; response rate as a datum; the concept of stimulus control; the concept of verbal behavior; and explicating the explanatory power of contingencies. Besides these achievements, however, Skinner also made some mistakes. Subsequent developments in radical behaviorist thought have attempted to remedy these mistakes. Moore's book presents a “party line” version of radical behaviorism. It focuses narrowly on a few of Skinner's concepts (mostly mentalism and verbal behavior) and contains no criticism of his mistakes. In fact, Moore adds a few mistakes of his own manufacture; for example, he insists that the mental realm does not exist—an unprovable and distracting assertion. The book's portrayal of behavior analysis would have been current around 1960; it mentions almost none of the developments since then. It also includes almost no developments in radical behaviorism since Skinner. Moore's book would give an unwary reader a highly distorted picture of contemporary behavior analysis and radical behaviorism.

  15. Total free radical species and oxidation equivalent in polluted air.

    Science.gov (United States)

    Wang, Guoying; Jia, Shiming; Niu, Xiuli; Tian, Haoqi; Liu, Yanrong; Chen, Xuefu; Li, Lan; Zhang, Yuanhang; Shi, Gaofeng

    2017-12-31

    Free radicals are the most important chemical intermediate or agent of the atmosphere and influenced by thousands of reactants. The free radicals determine the oxidizing power of the polluted air. Various gases present in smog or haze are oxidants and induce organ and cellular damage via generation of free radical species. At present, however, the high variability of total free radicals in polluted air has prevented the detection of possible trends or distributions in the concentration of those species. The total free radicals are a kind of contaminants with colorless, tasteless characteristics, and almost imperceptible by human body. Here we present total free radical detection and distribution characteristics, and analyze the effects of total free radicals in polluted air on human health. We find that the total free radical values can be described by not only a linear dependence on ozone at higher temperature period, but also a linear delay dependence on particulate matter at lower temperature period throughout the measurement period. The total free radical species distribution is decrease from west to east in Lanzhou, which closely related to the distribution of the air pollutants. The total free radical oxidation capacity in polluted air roughly matches the effects of tobacco smoke produced by the incomplete combustion of a controlled amount of tobacco in a smoke chamber. A relatively unsophisticated chromatographic fingerprint similarity is used for indicating preliminarily the effect of total free radicals in polluted air on human health. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Electron spin resonance study of radicals in irradiated polyethylene

    International Nuclear Information System (INIS)

    Fujimura, Takashi

    1979-02-01

    In order to elucidate radiation effect in polyethylene, the nature and behavior of radicals produced in polyethylene and the model compound of polyethylene irradiated at 77 0 K were studied by using electron spin resonance. The structure of radical pairs, which are composed of two radicals produced very closely each other, was investigated in drawn polyethylene and the single crystal of n-eicosane. The radical pairs of intrachain type and interchain type were found in polyethylene and n-eicosane respectively. It was suggested that these two types of radical pairs are the precursors of double bonds and crosslinks respectively. The thermal decay reactions of radicals themselves produced in irradiated polyethylene were investigated. It was made clear that the short range distances between two radicals play an important role in the decay reaction of alkyl radicals at low temperatures. The trapping regions of radicals were studied and it was clarified that allyl radicals, which are produced by the reaction of alkyl radicals with double bonds, are trapped both in the crystalline and non-crystalline regions. (author)

  17. OH radical induced depolymerization of poly(methacrylic acid)

    Science.gov (United States)

    Ulanski, Piotr; Bothe, Eberhard; von Sonntag, Clemens

    1999-05-01

    Hydroxyl radicals (generated pulse radiolytically in dilute N 2O-saturated aqueous solutions) react with poly(methacrylic acid) producing two kinds of radicals. The primary radical is converted into a secondary one by H-abstraction ( k=3.5 × 10 2 s -1) as monitored by changes in the UV spectrum. Subsequently, the secondary radicals undergo chain scission ( k=1.8 s -1 at pH 7-9). This process has been followed both by spectrophotometry as well as by conductometry. In competition with the bimolecular decay of the radicals the ensuing end-chain radicals undergo efficient depolymerization resulting in the release of monomer. Since the lifetime of the radicals is much longer at high pH, where the polymer attains a rod-like conformation, depolymerization is most efficient in basic solution.

  18. Reactions of carbonate radical with cobalt(II) aminopolycarboxylates

    International Nuclear Information System (INIS)

    Mandal, P.C.; Bardhan, D.K.; Bhattacharyya, S.N.

    1992-01-01

    Reactions of carbonate (CO 3 - radical) and bicarbonate (HCO 3 radical) radicals generated by photolysis of a carbonate or bicarbonate solution at pH 11.2 and 8.5, respectively, with Co(II) complexes of iminodiacetic acid (IDA) and ethylenediaminetetraacetic acid (EDTA) have been studied. The rate constants for the reactions were in the order of 10 6 -10 7 dm 3 mol -1 s -1 . From the time-resolved spectroscopy of the products formed after reaction of CO 3 - radical or HCO 3 radical, it is observed that CO 3 - radical or HCO 3 radical oxidize the metal center to its higher oxidation state. (author) 26 refs.; 2 figs.; 1 tab

  19. Ion microbeam irradiation for radiobiology and radical chemistry: status and prospect

    Energy Technology Data Exchange (ETDEWEB)

    Khodja, H, E-mail: hicham.khodja@cea.fr [CEA, IRAMIS, SIS2M, LEEL, 91191 Gif-sur-Yvette (France); CNRS, UMR 3299, SIS2M, LEEL, 91191 Gif-sur-Yvette (France)

    2011-01-01

    Ion microbeams are commonly used to study local irradiation effects in living cells, as it has been established that ion beam irradiations can lead to deleterious changes in cells that are not struck directly by the microbeam. Such changes, which take place over distances long compared to the size of the irradiation spot and for times long compared to the time of irradiation, are collectively termed radiation-induced bystander effect or RIBE. Free-radical chemistry is frequently invoked to explain the RIBE but no unified model is available at present. Ion microbeams when coupled with advanced methods for observing free radicals are the tools of choice for investigating the chemistry and biological processes governing RIBE.

  20. N-Chlorosuccinimide (NCS): A Novel Initiator for Atom Transfer Radical Polymerization of Methyl Methacrylate

    Institute of Scientific and Technical Information of China (English)

    WANG,Xia-Yan; CHANG,Li-Qun; ZHOU,Hong; ZHANG,Ke-Da

    2006-01-01

    Atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was achieved, using N-chlorosuccinimide (NCS) as an initiator together with catalytic system CuCl/PMDETA (N,N,N',N',N"-pentamethyldiethyl-enetriamine), CuCl/MA5-DETA (N,N,N',N',N"-penta(methylacrylate)diethylenetriamine), and CuCl/bipy (bipy=2,2'-bipyridyl) respectively. The results indicated that the polymerization possessed typical controlled/living radical polymerization characteristics. The analysis for terminal group of obtained polymer by 1H NMR proved that NCS is an initiator for ATRP. In comparison with NBS, the polymerization rate was slower and the resulted polymer had narrower molecular weight distribution (MWD) when NCS was employed as the initiator.

  1. Polymethylene-based copolymers by polyhomologation or by its combination with controlled/living and living polymerizations

    KAUST Repository

    Zhang, Hefeng

    2014-01-20

    Polyhomologation, recently developed by Shea, is a borane-initiated living polymerization of ylides leading to linear polymethylenes (C1 polymerization) with controlled molecular weight, low polydispersity, and well-defined structures. In this Review, the copolyhomologation of different ylides as well as the combination of polyhomologation with controlled/living (nitroxide-mediated, atom transfer radical, reversible addition-fragmentation chain-transfer) and living (ring opening, anionic) polymerizations is discussed. Polyhomologation of ylides, in combination with living and controlled/living polymerizations, leads to a plethora novel well-defined polymethylene (polyethylene)-based polymeric materials, which are very important for understanding/improving the behavior of industrial polyethylenes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Classrooms as Radical Spaces of Possibilities

    Science.gov (United States)

    Sahni, Urvashi

    2016-01-01

    This article provides a brief snapshot of a girls school in Northern India called Prerna. Girls in India are unwanted, unequal and unsafe. Every year a million of them are killed in the womb. One third of the world's child brides (read "girl slaves") are in India. They live their lives in a grim, complex context where, gender, poverty…

  3. Living Gluten Free

    Science.gov (United States)

    ... Disease" Articles Celiac Disease Changes Everything / What is Celiac Disease? / Symptoms, Diagnosis & Treatment / Four Inches and Seven Pounds… / Learning to Live Well with Celiac Disease / Living Gluten-Free Spring 2015 Issue: Volume 10 ...

  4. Modelling live forensic acquisition

    CSIR Research Space (South Africa)

    Grobler, MM

    2009-06-01

    Full Text Available This paper discusses the development of a South African model for Live Forensic Acquisition - Liforac. The Liforac model is a comprehensive model that presents a range of aspects related to Live Forensic Acquisition. The model provides forensic...

  5. Radical intermediates involved in the bleaching of the carotenoid crocin. Hydroxyl radicals, superoxide anions and hydrated electrons

    International Nuclear Information System (INIS)

    Bors, W.; Saran, M.; Michel, C.

    1982-01-01

    The participation of the primary radicals in the bleaching of aqueous solutions of the carotenoid crocin by ionizing radiation was investigated, employing both X-radiolysis and pulse radiolysis. The pulse-radiolytic data demonstrated a very rapid diffusion-controlled attack by both hydroxyl radicals (radicalsOH) and hydrated electrons (e - sub(aq)), while superoxide anions (O 2 - ) did not react at all. The site of the initial reaction of these radicals was not limited to the polyene chromophore. Slower secondary reactions involving crocin alkyl or peroxy radicals contribute mainly to the overall bleaching, in particular during steady-state irradiation. (author)

  6. Even free radicals should follow some rules: a guide to free radical research terminology and methodology.

    Science.gov (United States)

    Forman, Henry Jay; Augusto, Ohara; Brigelius-Flohe, Regina; Dennery, Phyllis A; Kalyanaraman, Balaraman; Ischiropoulos, Harry; Mann, Giovanni E; Radi, Rafael; Roberts, L Jackson; Vina, Jose; Davies, Kelvin J A

    2015-01-01

    Free radicals and oxidants are now implicated in physiological responses and in several diseases. Given the wide range of expertise of free radical researchers, application of the greater understanding of chemistry has not been uniformly applied to biological studies. We suggest that some widely used methodologies and terminologies hamper progress and need to be addressed. We make the case for abandonment and judicious use of several methods and terms and suggest practical and viable alternatives. These changes are suggested in four areas: use of fluorescent dyes to identify and quantify reactive species, methods for measurement of lipid peroxidation in complex biological systems, claims of antioxidants as radical scavengers, and use of the terms for reactive species. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Radiation-electrochemistry of the colloidal gold micro-electrode: Hydrogen formation by organic free radicals

    International Nuclear Information System (INIS)

    Westerhausen, J.; Henglein, A.; Lilie, J.

    1981-01-01

    Various organic free radicals as well as Ni + ions produce hydrogen in the presence of some 10 -4 M of colloidal gold. The gold catalyst was prepared via the reduction of HAuCl 4 either thermally by citrate or by γ-irradiation. The organic radicals were radiolytically produced. The mechanism of H 2 formation includes electron transfer from the organic radicals to the gold particles, storage of a large number of electrons per gold particle, conversion of the electrons into adsorbed H-atoms and desorption of the latter to form H 2 . - The rates of some of these steps were measured using the method of pulse radiolysis. 1-Hydroxy-1-methyl ethyl radicals, (CH 3 ) 2 COH, react with colloidal gold particles almost diffusion controlled provided that the gold particles are not charged with excess electrons. Charged gold particles react at a substantially lower rate. The stored electrons live seconds or even minutes depending on their number per gold particle. In the stationary state, up to 0.38 Coulomb of electrons could be stored per liter of a 2.9x10 -4 molar gold solution, each gold particle carrying about 39 electrons. A comparison is also made between the catalytic activities of colloidal gold and silver. Due to the relative fast conversion of electrons into adsorbed H-atoms, colloidal gold has less capacity for the storage of electrons than colloidal silver. - The dependence of the hydrogen yield on the pH of the solution, the concentration of gold, the size of the gold particles, the concentration of the polyvinyl alcohol stabilizer, and the intensity of radiation was also investigated. At high intensities, some of the radicals are destroyed in a gold catalysed disproportionation. (orig.)

  8. The effect of near-infrared MLS laser radiation on cell membrane structure and radical generation.

    Science.gov (United States)

    Kujawa, Jolanta; Pasternak, Kamila; Zavodnik, Ilya; Irzmański, Robert; Wróbel, Dominika; Bryszewska, Maria

    2014-09-01

    The therapeutic effects of low-power laser radiation of different wavelengths and light doses are well known, but the biochemical mechanism of the interaction of laser light with living cells is not fully understood. We have investigated the effect of MLS (Multiwave Locked System) laser near-infrared irradiation on cell membrane structure, functional properties, and free radical generation using human red blood cells and breast cancer MCF-4 cells. The cells were irradiated with low-intensity MLS near-infrared (simultaneously 808 nm, continuous emission and 905 nm, pulse emission, pulse-wave frequency, 1,000 or 2,000 Hz) laser light at light doses from 0 to 15 J (average power density 212.5 mW/cm(2), spot size was 3.18 cm(2)) at 22 °C, the activity membrane bound acetylcholinesterase, cell stability, anti-oxidative activity, and free radical generation were the parameters used in characterizing the structural and functional changes of the cell. Near-infrared low-intensity laser radiation changed the acetylcholinesterase activity of the red blood cell membrane in a dose-dependent manner: There was a considerable increase of maximal enzymatic rate and Michaelis constant due to changes in the membrane structure. Integral parameters such as erythrocyte stability, membrane lipid peroxidation, or methemoglobin levels remained unchanged. Anti-oxidative capacity of the red blood cells increased after MLS laser irradiation. This irradiation induced a time-dependent increase in free radical generation in MCF-4 cells. Low-intensity near-infrared MLS laser radiation induces free radical generation and changes enzymatic and anti-oxidative activities of cellular components. Free radical generation may be the mechanism of the biomodulative effect of laser radiation.

  9. O Behaviorismo Radical como filosofia da mente Radical Behaviorism as philosophy of mind

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Lopes

    2003-01-01

    Full Text Available O Behaviorismo Radical de B. F. Skinner é constantemente acusado de eliminar a mente de sua explicação do comportamento humano. Uma análise do livro The Concept of Mind, de Gilbert Ryle, sugere a possibilidade de defender a existência de uma mente relacional, diferente da categoria de existência da mente defendida em interpretações cartesianas (mente substancial. A análise de alguns textos de Skinner sugere que o conceito de uma mente relacional também pode ser defendido no Behaviorismo Radical. Esse fato, culminaria na possibilidade de que, além de filosofia da Ciência do Comportamento, o Behaviorismo Radical, também pode ser uma filosofia da mente, o que traria conseqüências ao estudo e à aplicação da Análise do Comportamento.B. F. Skinner's Radical Behaviorism has been repeatedly accused of eliminating the mind from its explanation of human behavior. An analysis of Gilbert Ryle's book, The Concept of Mind, suggests the possibility of defending the existence of a relational mind, different from the category of existence of mind defended in Cartesian interpretations (substantial mind. The analysis of some texts of Skinner suggests that the concept of a relational mind can also be defended in Radical Behaviorism. This fact would lead to the possibility that, beyond a philosophy of Behavior Science, Radical Behaviorism may also be a philosophy of mind, which would bring consequences to the study and application of Analysis of Behavior.

  10. Preoperative radiochemotherapy and radical surgery in comparison with radical surgery alone

    International Nuclear Information System (INIS)

    Mohr, C.; Schettler, D.; Bohndorf, W.

    1994-01-01

    A multicentric, randomized study of squamous cell carcinoma (SCC) of the oral cavity and the oropharynx has been undertaken by DOeSAK. The results after radical surgery alone have been compared with the results of combined preoperative radiochemotherapy followed by radical surgery. Patients with primary (biopsy proven) SCC of the oral cavity or the oropharynx with tumor nodes metastasis (TNM) stages T2-4, N0-3, M0 were included in the study. A total of 141 patients were treated by radical surgery alone, whereas 127 patients were treated by radical surgery preceded by preoperative radiochemotherapy. The pre-operative treatment consisted of conventionally fractioned irradiation on the primary and the regional lymph nodes with a total dose of 36 Gy (5 x 2 Gy per week) and low-dose cisplatin chemotherapy with 5 x 12.5 mg cisplatin per m 2 of body surface during the first week of treatment. Radical surgery according to be DOeSAK definitions (DOeSAK, 1982) was performed after a delay of 10-14 days. During the follow-up period, 28.2% of all patients suffered from locoregional recurrence, and 27.2% of the patients died. The percentages were higher after radical surgery alone for locoregional recurrence (31% and 15.6%) and for death (28% and 18.6%). The life-table analysis showed improved survival rates of 4.5% after 1 year and 8.3% after 2 years in the group of patients treated with combined therapy. The demonstrated improvement appeared to be significant with the Gehan-Wilcoxon test as well as with the log rank test below a P value of 5%. (au) (29 refs.)

  11. Leghemoglobin-derived radicals. Evidence for multiple protein-derived radicals and the initiation of peribacteroid membrane damage

    DEFF Research Database (Denmark)

    Moreau, S; Davies, Michael Jonathan; Mathieu, C

    1996-01-01

    , with the consequent generation of lipid-derived radicals. The formation of such radicals may result in the depletion of membrane antioxidants and the initiation of lipid peroxidation. This transfer of damage from the heme center via the protein surface to neighboring membranes may be of considerable biological......-derived phenoxyl radical present at Tyr-133 in the soybean protein and Tyr-138 in the lupin protein. To obtain further information on these protein radicals and their potential interaction with the physiologically important peribacteroid membrane (which surrounds the microsymbiont in vivo), EPR spin trapping......); these radicals may be side chain- or alpha-carbon-derived, their exact sites have not been determined. Some of these radicals are on the protein surface and may be key intermediates in the formation of protein dimers. These radicals have been shown to be capable of reacting with peribacteroid membrane fractions...

  12. A novel plasma source for sterilization of living tissues

    International Nuclear Information System (INIS)

    Martines, E; Zuin, M; Cavazzana, R; Gazza, E; Serianni, G; Spagnolo, S; Spolaore, M; Leonardi, A; Deligianni, V; Brun, P; Aragona, M; Castagliuolo, I; Brun, P

    2009-01-01

    A source for the production of low-power plasmas at atmospheric pressure, to be used for the nondamaging sterilization of living tissues, is presented. The source, powered by radiofrequency and working with a helium flow, has a specific configuration, studied to prevent the formation of electric arcs dangerous to living matter. It is capable of killing different types of bacteria with a decimal reduction time of 1-2 min; on the contrary, human cells such as conjunctival fibroblasts were found to be almost unharmed by the plasma. A high concentration of OH radicals, likely to be the origin of the sterilizing effect, is detected through their UV emission lines. The effect of the UV and the OH radicals on the fibroblasts was analysed and no significant effects were detected.

  13. Taking a radical position: Evidence for position specific radical representations in Chinese character recognition using masked priming ERP

    Directory of Open Access Journals (Sweden)

    I-Fan eSu

    2012-09-01

    Full Text Available In the investigation of orthographic representation of Chinese characters, one question that has stimulated much research is whether radicals (character components are specified for spatial position in a character (e.g. Ding, Peng, & Taft, 2004; Tsang & Chen, 2009. Differing from previous work, component or radical position information in this study is conceived in terms of relative frequency across different positions of characters containing it. A lexical decision task in a masked priming paradigm focusing on radicals with preferred position of occurrence was conducted. A radical position that encompasses more characters than other positions was identified to be the preferred position of a particular radical. The prime that was exposed for 96ms might share a radical with the target in the same or different positions. Moreover, the shared radical appeared either in its preferred or non-preferred position in the target. While response latencies only revealed the effect of graphical similarity, both effects of graphical similarity and radical position preference were found in the ERP results. The former effect was reflected in greater positivity in occipital P1 and greater negativity in N400 for radicals in different positions in prime and target characters. The latter effect manifested as greater negativity in occipital N170 and greater positivity in frontal P200 in the same time window elicited by radicals in their non-preferred position. Equally interesting was the reversal of the effect of radical position preference in N400 with greater negativity associated with radicals in preferred position. These findings identify the early ERP components associated with activation of position-specific radical representations in the orthographic lexicon, and reveal the change in the nature of competition from processing at the radical level to the lexical level.

  14. Exploring the dynamics of hydrogen atom release from the radical-radical reaction of O(3P) with C3H5

    International Nuclear Information System (INIS)

    Joo, Sun-Kyu; Kwon, Lee-Kyoung; Lee, Hohjai; Choi, Jong-Ho

    2004-01-01

    The gas-phase radical-radical reaction dynamics of O( 3 P)+C 3 H 5 →H( 2 S)+C 3 H 4 O was studied at an average collision energy of 6.4 kcal/mol in a crossed beam configuration. The ground-state atomic oxygen [O( 3 P)] and allyl radicals (C 3 H 5 ) were generated by the photolysis of NO 2 and the supersonic flash pyrolysis of allyl iodide, respectively. Nascent hydrogen atom products were probed by the vacuum-ultraviolet-laser induced fluorescence spectroscopy in the Lyman-α region centered at 121.6 nm. With the aid of the CBS-QB3 level of ab initio theory, it has been found that the barrierless addition of O( 3 P) to C 3 H 5 forms the energy-rich addition complexes on the lowest doublet potential energy surface, which are predicted to undergo a subsequent direct decomposition step leading to the reaction products H+C 3 H 4 O. The major counterpart C 3 H 4 O of the probed hydrogen atom is calculated to be acrolein after taking into account the factors of barrier height, reaction enthalpy, and the number of intermediates involved along the reaction pathway. The nascent H-atom Doppler profile analysis shows that the average center-of-mass translational energy of the H+C 3 H 4 O products and the fraction of the total available energy released as the translational energy were determined to be 3.83 kcal/mol and 0.054, respectively. On the basis of comparison with statistical calculations, the reaction proceeds through the formation of short-lived addition complexes rather than statistical, long-lived intermediates, and the polyatomic acrolein product is significantly internally excited at the moment of the decomposition

  15. Exploring the dynamics of hydrogen atom release from the radical-radical reaction of O(3P) with C3H5

    Science.gov (United States)

    Joo, Sun-Kyu; Kwon, Lee-Kyoung; Lee, Hohjai; Choi, Jong-Ho

    2004-05-01

    The gas-phase radical-radical reaction dynamics of O(3P)+C3H5→H(2S)+C3H4O was studied at an average collision energy of 6.4 kcal/mol in a crossed beam configuration. The ground-state atomic oxygen [O(3P)] and allyl radicals (C3H5) were generated by the photolysis of NO2 and the supersonic flash pyrolysis of allyl iodide, respectively. Nascent hydrogen atom products were probed by the vacuum-ultraviolet-laser induced fluorescence spectroscopy in the Lyman-α region centered at 121.6 nm. With the aid of the CBS-QB3 level of ab initio theory, it has been found that the barrierless addition of O(3P) to C3H5 forms the energy-rich addition complexes on the lowest doublet potential energy surface, which are predicted to undergo a subsequent direct decomposition step leading to the reaction products H+C3H4O. The major counterpart C3H4O of the probed hydrogen atom is calculated to be acrolein after taking into account the factors of barrier height, reaction enthalpy, and the number of intermediates involved along the reaction pathway. The nascent H-atom Doppler profile analysis shows that the average center-of-mass translational energy of the H+C3H4O products and the fraction of the total available energy released as the translational energy were determined to be 3.83 kcal/mol and 0.054, respectively. On the basis of comparison with statistical calculations, the reaction proceeds through the formation of short-lived addition complexes rather than statistical, long-lived intermediates, and the polyatomic acrolein product is significantly internally excited at the moment of the decomposition.

  16. Ultraviolet photodissociation dynamics of the benzyl radical.

    Science.gov (United States)

    Song, Yu; Zheng, Xianfeng; Lucas, Michael; Zhang, Jingsong

    2011-05-14

    Ultraviolet (UV) photodissociation dynamics of jet-cooled benzyl radical via the 4(2)B(2) electronically excited state is studied in the photolysis wavelength region of 228 to 270 nm using high-n Rydberg atom time-of-flight (HRTOF) and resonance enhanced multiphoton ionization (REMPI) techniques. In this wavelength region, H-atom photofragment yield (PFY) spectra are obtained using ethylbenzene and benzyl chloride as the precursors of benzyl radical, and they have a broad peak centered around 254 nm and are in a good agreement with the previous UV absorption spectra of benzyl. The H + C(7)H(6) product translational energy distributions, P(E(T))s, are derived from the H-atom TOF spectra. The P(E(T)) distributions peak near 5.5 kcal mol(-1), and the fraction of average translational energy in the total excess energy, , is ∼0.3. The P(E(T))s indicate the production of fulvenallene + H, which was suggested by recent theoretical studies. The H-atom product angular distribution is isotropic, with the anisotropy parameter β ≈ 0. The H/D product ratios from isotope labeling studies using C(6)H(5)CD(2) and C(6)D(5)CH(2) are reasonably close to the statistical H/D ratios, suggesting that the H/D atoms are scrambled in the photodissociation of benzyl. The dissociation mechanism is consistent with internal conversion of the electronically excited benzyl followed by unimolecular decomposition of the hot benzyl radical on the ground state.

  17. The Embodied Brain: Towards a Radical Embodied Cognitive Neuroscience

    Directory of Open Access Journals (Sweden)

    Julian eKiverstein

    2015-05-01

    Full Text Available In this programmatic paper we explain why a radical embodied cognitive neuroscience is needed. We argue for such a claim based on problems that have arisen in cognitive neuroscience for the project of localizing function to specific brain structures. The problems come from research concerned with functional and structural connectivity that strongly suggests that the function a brain region serves is dynamic, and changes over time. We argue that in order to determine the function of a specific brain area, neuroscientists need to zoom out and look at the larger organism-environment system. We therefore argue that instead of looking to cognitive psychology for an analysis of psychological functions, cognitive neuroscience should look to an ecological dynamical psychology. A second aim of our paper is to develop an account of embodied cognition based on the inseparability of cognitive and emotional processing in the brain. We argue that emotions are best understood in terms of action readiness (Frijda 1986, 2007 in the context of the organism’s ongoing skillful engagement with the environment (Rietveld 2008; Bruineberg & Rietveld 2014; Kiverstein & Rietveld 2015. States of action readiness involve the whole living body of the organism, and are elicited by possibilities for action in the environment that matter to the organism. Since emotion and cognition are inseparable processes in the brain it follows that what is true of emotion is also true of cognition. Cognitive processes are likewise processes taking place in the whole living body of an organism as it engages with relevant possibilities for action.

  18. Resonance Raman study of benzyl radical

    DEFF Research Database (Denmark)

    Langkilde, F.W.; Bajdor, K.; Wilbrandt, R.

    1992-01-01

    Time-resolved resonance Raman spectra are obtained of benzyl radicals created by laser flash photolysis of benzylchloride and diphenylacetone in solution. The spectra are obtained in resonance with the intense 2 2A2-1 B-2(2) transition of benzyl. The strong Raman bands are assigned to totally...... symmetric a1 modes. The remaining observed bands are tentatively assigned to fundamental modes of b1, a2, and b2 symmetry, and to overtones and combinations. The resonance Raman spectra are found to be quite different from previous fluorescence spectra of benzyl, and the origins of these differences...

  19. Dissociative Photoionization of the Elusive Vinoxy Radical.

    Science.gov (United States)

    Adams, Jonathan D; Scrape, Preston G; Lee, Shih-Huang; Butler, Laurie J

    2017-08-24

    These experiments report the dissociative photoionization of vinoxy radicals to m/z = 15 and 29. In a crossed laser-molecular beam scattering apparatus, we induce C-Cl bond fission in 2-chloroacetaldehyde by photoexcitation at 157 nm. Our velocity measurements, combined with conservation of angular momentum, show that 21% of the C-Cl photofission events form vinoxy radicals that are stable to subsequent dissociation to CH 3 + CO or H + ketene. Photoionization of these stable vinoxy radicals, identified by their velocities, which are momentum-matched with the higher-kinetic-energy Cl atom photofragments, shows that the vinoxy radicals dissociatively photoionize to give signal at m/z = 15 and 29. We calibrated the partial photoionization cross section of vinoxy to CH 3 + relative to the bandwidth-averaged photoionization cross section of the Cl atom at 13.68 eV to put the partial photoionization cross sections on an absolute scale. The resulting bandwidth-averaged partial cross sections are 0.63 and 1.3 Mb at 10.5 and 11.44 eV, respectively. These values are consistent with the upper limit to the cross section estimated from a study by Savee et al. on the O( 3 P) + propene bimolecular reaction. We note that the uncertainty in these values is primarily dependent on the signal attributed to C-Cl primary photofission in the m/z = 35 (Cl + ) time-of-flight data. While the value is a rough estimate, the bandwidth-averaged partial photoionization cross section of vinoxy to HCO + calculated from the signal at m/z = 29 at 11.53 eV is approximately half that of vinoxy to CH 3 + . We also present critical points on the potential energy surface of the vinoxy cation calculated at the G4//B3LYP/6-311++G(3df,2p) level of theory to support the observation of dissociative ionization of vinoxy to both CH 3 + and HCO + .

  20. Processing of free radical damaged DNA bases

    International Nuclear Information System (INIS)

    Wallace, S.

    2003-01-01

    Free radicals produced during the radiolysis of water gives rise to a plethora of DNA damages including single strand breaks, sites of base loss and a wide variety of purine and pyrimidine base lesions. All these damages are processed in cells by base excision repair. The oxidative DNA glycosylases which catalyze the first step in the removal of a base damage during base excision repair evolved primarily to protect the cells from the deleterious mutagenic effects of single free radical-induced DNA lesions arising during oxidative metabolism. This is evidenced by the high spontaneous mutation rate in bacterial mutants lacking the oxidative DNA glycosylases. However, when a low LET photon transverses the DNA molecule, a burst of free radicals is produced during the radiolysis of water that leads to the formation of clustered damages in the DNA molecule, that are recognized by the oxidative DNA glycosylases. When substrates containing two closely opposed sugar damages or base and sugar damages are incubated with the oxidative DNA glycosylases in vitro, one strand is readily incised by the lyase activity of the DNA glycosylase. Whether or not the second strand is incised depends on the distance between the strand break resulting from the incised first strand and the remaining DNA lesion on the other strand. If the lesions are more than two or three base pairs apart, the second strand is readily cleaved by the DNA glycosylase, giving rise to a double strand break. Even if the entire base excision repair system is reconstituted in vitro, whether or not a double strand break ensues depends solely upon the ability of the DNA glycosylase to cleave the second strand. These data predicted that cells deficient in the oxidative DNA glycosylases would be radioresistant while those that overproduce an oxidative DNA glycosylase would be radiosensitive. This prediction was indeed borne in Escherichia coli that is, mutants lacking the oxidative DNA glycosylases are radioresistant

  1. Metal-Diazo Radicals of α-Carbonyl Diazomethanes

    Science.gov (United States)

    Li, Feifei; Xiao, Longqiang; Liu, Lijian

    2016-03-01

    Metal-diazo radicals of α-carbonyl diazomethanes are new members of the radical family and are precursors to metal-carbene radicals. Herein, using electron paramagnetic resonance spectroscopy with spin-trapping, we detect diazo radicals of α-carbonyl diazomethanes, induced by [RhICl(cod)]2, [CoII(por)] and PdCl2, at room temperature. The unique quintet signal of the Rh-diazo radical was observed in measurements of α-carbonyl diazomethane adducts of [RhICl(cod)]2 in the presence of 5,5-dimethyl-pyrroline-1-N-oxide (DMPO). DFT calculations indicated that 97.2% of spin density is localized on the diazo moiety. Co- and Pd-diazo radicals are EPR silent but were captured by DMPO to form spin adducts of DMPO-N• (triplet-of-sextets signal). The spin-trapping also provides a powerful tool for detection of metal-carbene radicals, as evidenced by the DMPO-trapped carbene radicals (DMPO-C•, sextet signal) and 2-methyl-2-nitrosopropane-carbene adducts (MNP-C•, doublet-of-triplets signal). The transformation of α-carbonyl diazomethanes to metal-carbene radicals was confirmed to be a two-step process via metal-diazo radicals.

  2. Peroxyl radical reactions with carotenoids in microemulsions: Influence of microemulsion composition and the nature of peroxyl radical precursor.

    Science.gov (United States)

    El-Agamey, Ali; McGarvey, David J

    2016-01-01

    The reactions of acetylperoxyl radicals with different carotenoids (7,7'-dihydro-β-carotene and ζ-carotene) in SDS and CTAC microemulsions of different compositions were investigated using laser flash photolysis (LFP) coupled with kinetic absorption spectroscopy. The primary objective of this study was to explore the influence of microemulsion composition and the type of surfactant used on the yields and kinetics of various transients formed from the reaction of acetylperoxyl radicals with carotenoids. Also, the influence of the site (hydrocarbon phases or aqueous phase) of generation of the peroxyl radical precursor was examined by using 4-acetyl-4-phenylpiperidine hydrochloride (APPHCl) and 1,1-diphenylacetone (11DPA) as water-soluble and lipid-soluble peroxyl radical precursors, respectively. LFP of peroxyl radical precursors with 7,7'-dihydro-β-carotene (77DH) in different microemulsions gives rise to the formation of three distinct transients namely addition radical (λmax=460 nm), near infrared transient1 (NIR, λmax=700 nm) and 7,7'-dihydro-β-carotene radical cation (77DH(•+), λmax=770 nm). In addition, for ζ-carotene (ZETA) two transients (near infrared transient1 (NIR1, λmax=660 nm) and ζ-carotene radical cation (ZETA(•+), λmax=730-740 nm)) are generated following LFP of peroxyl radical precursors in the presence of ζ-carotene (ZETA) in different microemulsions. The results show that the composition of the microemulsion strongly influences the observed yield and kinetics of the transients formed from the reactions of peroxyl radicals (acetylperoxyl radicals) with carotenoids (77DH and ZETA). Also, the type of surfactant used in the microemulsions influences the yield of the transients formed. The dependence of the transient yields and kinetics on microemulsion composition (or the type of surfactant used in the microemulsion) can be attributed to the change of the polarity of the microenvironment of the carotenoid. Furthermore, the nature of

  3. NOx removal characteristics of corona radical shower with ammonia and methylamine radical injections

    Energy Technology Data Exchange (ETDEWEB)

    Urashima, K.; Ara, M.; Chang, J.S. [McMaster Univ., Hamilton, ON (Canada). Dept. of Engineering Physics; Uchida, Y. [Aichi Inst. of Technology, (Japan). Dept. of Engineering

    2010-07-01

    Air pollutants such as nitrogen oxides (NOx) and sulfur oxides (SOx) are the major cause of acid rain. There are different types of NOx and SOx conversion techniques such as wet scrubber, selective catalytic reactor, sorbent injection, and low NOx burner. Non-thermal plasma techniques have also been utilized in commercial plants, but the energy efficiency of the non-thermal plasma reactors have not yet been optimized. The direct plasma treatments of flue gases including, the electron beam, barrier discharge and pulsed corona reactors, may lose input energy to activate unwanted components of flue gases such as carbon dioxide (CO{sub 2}) and nitrogen (N{sub 2}). The corona discharge ammonia radical shower system has demonstrated significant NOx removal with higher energy efficiency for large bench scale and pilot plant tests for combustion exhausts. An experiment has also demonstrated that methane can replace ammonia as an injection gas with less NOx removal efficiency. This paper presented an experimental investigation that compared methylamine radical injection with traditional ammonia and methane radical injections. The paper discussed the bench scale test facilities and corona radical shower plasma reactor. It was concluded that the processes to form ammonium nitrate could be observed from trace white solid particles deposited on the reactor wall as observed by scanning electron microscopy pictures. 10 refs., 5 figs., 2 appendices.

  4. Encapsulation of Gibbsite platelets with free radical and controlled radical emulsion polymerization approaches, a small review

    NARCIS (Netherlands)

    Loiko, O.P.; Spoelstra, A.B.; van Herk, A.M.; Meuldijk, J.; Heuts, J.P.A.

    2016-01-01

    Water-borne anisotropic polymer-Gibbsite latex particles were prepared by a conventional and an atom transfer radical polymerisation (ATRP) based starved-feed emulsion polymerisation without any chemical modification of the platelet surface. Anionic co-oligomers, synthesised via ATRP, were used in

  5. Nitroxide-mediated controlled radical polymerisation: towards control of molar mass Controlled Radical Polymerisation

    NARCIS (Netherlands)

    Bon, S.A.F.; Bergman, F.A.C.; Es, van J.J.G.S.; Klumperman, B.; German, A.L.; Matyjaszewski, K.

    1998-01-01

    The mechanism of the TEMPO-mediated controlled radical polymerization of styrene in bulk is discussed. It is shown that the isotropic correlation time (tc) of a nitroxide can be used as a measure of the diffusive rate coefficient of trapping (ketD). A general empirical relationship for the density

  6. Electron spin resonance spectroscopy of organic radicals spectroscopy of organic radicals

    CERN Document Server

    Gerson, Fabian

    2006-01-01

    ""This book should serve as a comprehensive one-volume source for finding what is known about the splitting constants and g factors of virtually all types of organic radicals."" Journal of the American Chemistry Society, 2004, Vol. 126 No. 20

  7. Hydrogen Radicals, Nitrogen Radicals, and the Production of Ozone in the Middle and Upper Troposphere

    Science.gov (United States)

    Bui, T. P.

    1997-01-01

    The concentrations of hydrogen radicals, OH and HO2, in the middle and upper troposphere were measured simultaneously with those of NO, O3,CO, H20, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field.

  8. Radical constructivism and radical constructedness: Luhmann's sociology of semantics, organizations, and self-organization

    NARCIS (Netherlands)

    Leydesdorff, L.

    2012-01-01

    Context: Using radical constructivism, society can be considered from the perspective of asking the question, "Who conceives of society?" In Luhmann’s social systems theory, this question itself is considered as a construct of the communication among reflexive agents. Problem: Structuration of

  9. COST Action CM1201 "Biomimetic Radical Chemistry": free radical chemistry successfully meets many disciplines

    Czech Academy of Sciences Publication Activity Database

    Ferreri, C.; Golding, B. T.; Jahn, Ullrich; Ravanat, J. L.

    2016-01-01

    Roč. 50, Suppl 1 (2016), S112-S128 ISSN 1071-5762 Institutional support: RVO:61388963 Keywords : radical enzyme * membrane stress * phospholipid remodeling * DNA damage and repair * biomimetic models * bio-inspired synthetic methodologies Subject RIV: CC - Organic Chemistry Impact factor: 3.188, year: 2016 http://www.tandfonline.com/doi/full/10.1080/10715762.2016.1248961

  10. Fast beam studies of free radical photodissociation

    Energy Technology Data Exchange (ETDEWEB)

    Cyr, Douglas Robert [Univ. of California, Berkeley, CA (United States)

    1993-11-01

    The photodissociation of free radicals is studied in order to characterize the spectroscopy and dissociation dynamics of the dissociative electronic states in these species. To accomplish this, a novel method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with a highly complementary form of photofragment translational spectroscopy. The optical spectroscopy of transitions to dissociative states is determined by monitoring the total photofragment yield as a function of dissociation photon energy. Branching ratios to various product channels, internal energy distributions of the fragments, bond dissociation energies, and the translational energy-dependent photofragment recoil angular distributions are then determined at selected excitation energies. A detailed picture of the dissociation dynamics can then be formulated, allowing insight concerning the interactions of potential energy surfaces involved in the dissociation. After an introduction to the concepts and techniques mentioned above, the experimental apparatus used in these experiments is described in detail. The basis and methods used in the treatment of data, especially in the dissociation dynamics experiments, are then put forward.

  11. Radical reactions in vivo - an overview

    International Nuclear Information System (INIS)

    Saran, M.; Bors, W.

    1990-01-01

    Generation of radicals in vivo depends on metabolic activities. The reactions are usually influenced by (i) the presence and concentration of oxygen, (ii) the availability of transition metals (effects of binding and compartimentalization), (iii) the level of reductants and antioxidants (e.g. nutritional effects). The effects of radicals are thought to be due to (i) membrane damage (affecting passive or active transport through altered fluidity/function interrelationships, intercellular messenging through modifications in the synthesis of prostaglandins and leukotrienes); (ii) protein damage (e.g. affecting membrane transporters, channel proteins, receptor or regulatory proteins, immunomodulators); (iii) damage to DNA. Defense mechanisms consist of (i) prevention of the 'spreading' of primary damage by low molecular weight antioxidants (e.g. vitamin E, GSH, vitamin C, β-carotene, uric acid); (ii) prevention or limitation of 'secondary' damage by enzymes (e.g. GSH-peroxidase, catalase, superoxide dismutase, DT-diaphorase) and/or chelators; (iii) repair processes, e.g. lipid degradation/membrane repair enzymes (phospholipases, peroxidases, some transferases and reductases), protein disposal or repair enzymes (proteases, GSSG-reductase), DNA degradation or repair enzymes (exonucleases III, endonucleases III and IV, glycosylases, polymerases). Recent hypotheses on a messenging function of the superoxide anion O 2 - are discussed and possible implications of cross-reactions between O 2 - and nitric oxide (endothelium-derived relaxing factor EDRF) are shortly mentioned. (orig.)

  12. The Rovibronic Spectra of the Cyclopentadienyl Radical

    Science.gov (United States)

    Sharma, Ketan; Miller, Terry A.; Stanton, John F.; Nesbitt, David

    2017-06-01

    Cyclopentadienyl (Cp) radical has been subject to numerous studies for the greater part of half a century. Experimental work has involved photo-electron spectroscopy, laser induced fluorescence excitation and emission, infrared absorption spectroscopy, and recently rotationally resolved spectra in the CH stretch region taken at JILA. Even more theoretical works appear in the literature, but substantial advances in computation have occurred since their completion. Cp's highly symmetric (D_{5h}) structure and doubly degenerate electronic ground (˜{X}^2E_1^{''}), which is subject to linear Jahn-Teller distortion, have been a great motivation for work on it. We have commenced new computational work to obtain a broad understanding of the electronic, vibrational, and rotational, i.e. rovibronic, structure of the Cp radical as revealed by its spectra, with particular emphasis on the new infrared spectra. The goal is to guide experiments and their analyses and reconcile results from spectroscopy and quantum chemistry calculations. T. Ichino, et al. J. Chem. Phys. 129, 084310 (2008) L. Yu, S. C. Foster, J. M. Williamson, M. C. Heaven and T. A. Miller J. Phys. Chem. 92, 4263 (1988) B. E. Applegate, A. J. Bezant and T. A. Miller J. Chem. Phys 114, 4869 (2001) D. Leicht, M. Kaufmann, G. Schwaab, and M. Havenith J. Chem. Phys. 145, 7 (2016), 074304.

  13. Mechanisms of radical removal by SO2

    DEFF Research Database (Denmark)

    Rasmussen, Christian Lund; Glarborg, Peter; Marshall, Paul

    2007-01-01

    It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H......(+M) reversible arrow HOSO(+M), HOSO + H/OH reversible arrow SO2 + H-2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find...... that the interaction of SO, with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H-2, as major products of the HOSO + H...

  14. Free Radicals and Extrinsic Skin Aging

    Directory of Open Access Journals (Sweden)

    Borut Poljšak

    2012-01-01

    Full Text Available Human skin is constantly directly exposed to the air, solar radiation, environmental pollutants, or other mechanical and chemical insults, which are capable of inducing the generation of free radicals as well as reactive oxygen species (ROS of our own metabolism. Extrinsic skin damage develops due to several factors: ionizing radiation, severe physical and psychological stress, alcohol intake, poor nutrition, overeating, environmental pollution, and exposure to UV radiation (UVR. It is estimated that among all these environmental factors, UVR contributes up to 80%. UV-induced generation of ROS in the skin develops oxidative stress, when their formation exceeds the antioxidant defence ability of the target cell. The primary mechanism by which UVR initiates molecular responses in human skin is via photochemical generation of ROS mainly formation of superoxide anion (O2−•, hydrogen peroxide (H2O2, hydroxyl radical (OH•, and singlet oxygen (1O2. The only protection of our skin is in its endogenous protection (melanin and enzymatic antioxidants and antioxidants we consume from the food (vitamin A, C, E, etc.. The most important strategy to reduce the risk of sun UVR damage is to avoid the sun exposure and the use of sunscreens. The next step is the use of exogenous antioxidants orally or by topical application and interventions in preventing oxidative stress and in enhanced DNA repair.

  15. Nitrate radicals and biogenic volatile organic compounds ...

    Science.gov (United States)

    Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO3) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO3-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol. Despite its long history of research and the significance of this topic in atmospheric chemistry, a number of important uncertainties remain. These include an incomplete understanding of the rates, mechanisms, and organic aerosol yields for NO3-BVOC reactions, lack of constraints on the role of heterogeneous oxidative processes associated with the NO3 radical, the difficulty of characterizing the spatial distributions of BVOC and NO3 within the poorly mixed nocturnal atmosphere, and the challenge of constructing appropriate boundary layer schemes and non-photochemical mechanisms for use in state-of-the-art chemical transport and chemistry–climate models. This review is the result of a workshop of the same title held at the Georgia Institute of Technology in June 2015. The first half of the review summarizes the current literature on NO3-BVOC chemistry, with a particular focus on recent advances in

  16. Radical cystectomy: Analysis of postoperative course

    Directory of Open Access Journals (Sweden)

    Jeremić Dimitrije

    2010-01-01

    Full Text Available Background/Aim. Radical cystectomy is a method of choice in the therapy of infiltrative bladder cancer. The aim of this research was to analyze postoperative course after radical cystectomy (length of hospitalization, most frequent complications and utilization of antibiotics and transfusions. Methods. We analyzed the records of 82 patients operated on in the Department of Urology, Clinical Center of Vojvodina, in a three-year period. In order to aquire data World Health Organization (WHO has developed Anatomical Therapeutic Chemical/Defined Daily Dose (ATC/DDD methodology. Defined daily dose (DDD is the assumed average maintenance dose per day for a drug use for its main indication. Results. Continent urinary derivation was preformed in 23.15% cases. Postoperative complications occurred in 18.29% of patients. Average blood utilization was 2.19 units. Blood utilization for continent derivations (n = 48 was 4.6 units, and incontinent ones 3.36 units. Totally 159.33 DDD/100 bed days were used. Conclusion. When preforming continent derivation there is a significant increase in blood utilization. Frequency of postoperative complications correlates to those reported in the literature.

  17. Hydroxyl radical induced degradation of ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Illés, Erzsébet, E-mail: erzsebet.illes@chem.u-szeged.hu [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary); Takács, Erzsébet [Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary); Dombi, András [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Gajda-Schrantz, Krisztina [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged (Hungary); EMPA, Laboratory for High Performance Ceramics, Duebendorf (Switzerland); Rácz, Gergely; Gonter, Katalin; Wojnárovits, László [Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary)

    2013-03-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1 mmol dm{sup −3}. For end product characterization {sup 60}Co γ-irradiation was used and the samples were evaluated either by taking their UV–vis spectra or by HPLC with UV or MS detection. The reactions of {sup ·}OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose. Highlights: ► In hydroxyl radical attack on the ring mainly hydroxylated products form ► The hydrated electron attacks the carboxyl group. ► Oxidative conditions are more effective in ibuprofen decomposition than reductive. ► Ecotoxicity of ibuprofen solution first increases then decreases with irradiation.

  18. Fast beam studies of free radical photodissociation

    International Nuclear Information System (INIS)

    Cyr, D.R.; California Univ., Berkeley, CA

    1993-11-01

    The photodissociation of free radicals is studied in order to characterize the spectroscopy and dissociation dynamics of the dissociative electronic states in these species. To accomplish this, a novel method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with a highly complementary form of photofragment translational spectroscopy. The optical spectroscopy of transitions to dissociative states is determined by monitoring the total photofragment yield as a function of dissociation photon energy. Branching ratios to various product channels, internal energy distributions of the fragments, bond dissociation energies, and the translational energy-dependent photofragment recoil angular distributions are then determined at selected excitation energies. A detailed picture of the dissociation dynamics can then be formulated, allowing insight concerning the interactions of potential energy surfaces involved in the dissociation. After an introduction to the concepts and techniques mentioned above, the experimental apparatus used in these experiments is described in detail. The basis and methods used in the treatment of data, especially in the dissociation dynamics experiments, are then put forward

  19. Ascorbyl radical disproportionation in reverse micellar systems

    Science.gov (United States)

    Gębicki, J. L.; Szymańska-Owczarek, M.; Pacholczyk-Sienicka, B.; Jankowski, S.

    2018-04-01

    Ascorbyl radical was generated by the pulse radiolysis method and observed with the fast kinetic spectrophotometry within reverse micelles stabilized by AOT in n-heptane or by Igepal CO-520 in cyclohexane at different water to surfactant molar ratio, w0. Rate constants for the disproportionation of the ascorbyl radicals were smaller than those for intermicellar exchange for both type of reverse micelles and slower than those in homogeneous aqueous solutions. However, they increased with increasing w0 for AOT/n-heptane system, while they decreased for Igepal CO-520 system. The absorption spectra of ascorbic acid AOT/n-heptane reverse micellar system showed that the "pH" sensed by this molecule is lower than that in respective homogeneous aqueous solutions. The obtained results were rationalized taking into account three main factors (i) preferential location of ascorbic acid molecules in the interfacial region of the both types of reverse micelles; (ii) postulate that the pH of the interface is lower than that of the water pool of reverse micelles and (iii) different structure of the interface of the reverse micelles made by AOT in n-heptane and those formed by Igepal CO-520 I cyclohexane. Some possible consequences of these findings are discussed.

  20. Hegel’s Gesture Towards Radical Cosmopolitanism

    Directory of Open Access Journals (Sweden)

    Shannon Brincat

    2009-09-01

    Full Text Available This is a preliminary argument of a much larger research project inquiring into the relation betweenHegel’s philosophical system and the project of emancipation in Critical International Relations Theory. Specifically, the paper examines how Hegel’s theory of recognition gestures towards a form of radical cosmopolitanism in world politics to ensure the conditions of rational freedom for all humankind. Much of the paper is a ground-clearing exercise defining what is ‘living’ in Hegel’s thought for emancipatory approaches in world politics, to borrow from Croce’s now famous question. It focuses on Hegel’s unique concept of freedom which places recognition as central in the formation of self-consciousness and therefore as a key determinant in the conditions necessary forhuman freedom to emerge in political community. While further research is needed to ascertain the precise relationship between Hegel’s recognition theoretic, emancipation and cosmopolitanism, it is contended that the intersubjective basis of Hegel’s concept of freedom through recognition necessitates some form of radical cosmopolitanism that ensures successful processes of recognition between all peoples, the precise institutional form of which remains unspecified.

  1. Anion photoelectron spectroscopy of radicals and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Travis, Taylor R. [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying 2Σ and 2π states of C2nH (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C2H and C4H. Other radicals studied include NCN and I3. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I3 revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

  2. Hydroxyl radical induced degradation of ibuprofen

    International Nuclear Information System (INIS)

    Illés, Erzsébet; Takács, Erzsébet; Dombi, András; Gajda-Schrantz, Krisztina; Rácz, Gergely; Gonter, Katalin; Wojnárovits, László

    2013-01-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1 mmol dm −3 . For end product characterization 60 Co γ-irradiation was used and the samples were evaluated either by taking their UV–vis spectra or by HPLC with UV or MS detection. The reactions of · OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose. Highlights: ► In hydroxyl radical attack on the ring mainly hydroxylated products form ► The hydrated electron attacks the carboxyl group. ► Oxidative conditions are more effective in ibuprofen decomposition than reductive. ► Ecotoxicity of ibuprofen solution first increases then decreases with irradiation

  3. Radicals of DNA and DNA nucleotides generated by ionising radiation

    International Nuclear Information System (INIS)

    Przybytniak, G.

    2004-01-01

    A first stage of cell processes leading to DNA damage of initiated by radical reactions. In a model system such transformations were generated by ionising radiation which involves production of electron loss and electron gain centers of the substrate and radical formation. Using cryogenic ESR spectroscopy it was found that the DNA nucleotides, which convert to radical anions upon electron capture undergo the separation of unpaired spin and charge due to protonation. Circular and linear dichroism studies enabled to conclude that iron ions(III) induce strong changes in the DNA helical structure indicating their coordination with nitrogen bases. The repair of DNA radicals produced via radiolytic oxidation, i.e. the guanine radical cation and the allyl type radical of thymine, is possible at elevated temperatures due to the involvement of sulphydryl groups. The influence of the thiol charge is then limited

  4. Acyclic diastereoselection in prochiral radical addition to prochiral olefins.

    Science.gov (United States)

    Sibi, Mukund P; Rheault, Tara R; Chandramouli, Sithamalli V; Jasperse, Craig P

    2002-03-27

    The stereochemical preference (syn or anti) when prochiral radicals add to prochiral acceptors is of fundamental interest. The primary focus of this research was to determine which factors influence the relative stereochemistry between the beta and gamma chiral centers when these are formed concurrently. While moderate diastereoselectivity was found for addition of alkyl (6a-d) and alpha-alkoxy radicals (16a-c) (15:1 anti). Steric influence in alkyl radical additions was difficult to evaluate due to decreased reactivity when using bulky reaction partners; however, more reactive alpha-alkoxy radicals, it was found that increasing steric bulk leads to moderate increases in selectivity. In addition, higher selectivity was observed when employing lanthanide Lewis acids whose environment (reactivity) was modified using achiral additives, suggesting a potentially simple means for selectivity enhancements in radical reactions. Overall these results indicate that significant stereoelectronic effects are necessary to achieve high levels of selectivity in prochiral radical additions to prochiral acceptors.

  5. Hypochlorite and superoxide radicals can act synergistically to induce fragmentation of hyaluronan and chondroitin sulphates

    DEFF Research Database (Denmark)

    Rees, Martin D; Hawkins, Clare Louise; Davies, Michael Jonathan

    2004-01-01

    at pH 7.4). Exposure of glycosaminoglycans to a MPO-H2O2-Cl- system or reagent HOCl generates long-lived chloramides [R-NCl-C(O)-R'] derived from the glycosamine N-acetyl functions. Decomposition of these species by transition metal ions gives polymer-derived amidyl (nitrogen-centred) radicals [R......-carboxybenzyl)hyponitrite] was demonstrated to be entirely chloramide dependent as no fragmentation occurred with the native polymers or when the chloramides were quenched by prior treatment with methionine. EPR spin-trapping experiments using 5,5-dimethyl1-pyrroline-N-oxide and 2-methyl-2-nitrosopropane have...

  6. Measurements of hydroxyl and hydroperoxy radicals during CalNex-LA: Model comparisons and radical budgets

    Science.gov (United States)

    Griffith, S. M.; Hansen, R. F.; Dusanter, S.; Michoud, V.; Gilman, J. B.; Kuster, W. C.; Veres, P. R.; Graus, M.; de Gouw, J. A.; Roberts, J.; Young, C.; Washenfelder, R.; Brown, S. S.; Thalman, R.; Waxman, E.; Volkamer, R.; Tsai, C.; Stutz, J.; Flynn, J. H.; Grossberg, N.; Lefer, B.; Alvarez, S. L.; Rappenglueck, B.; Mielke, L. H.; Osthoff, H. D.; Stevens, P. S.

    2016-04-01

    Measurements of hydroxyl (OH) and hydroperoxy (HO2*) radical concentrations were made at the Pasadena ground site during the CalNex-LA 2010 campaign using the laser-induced fluorescence-fluorescence assay by gas expansion technique. The measured concentrations of OH and HO2* exhibited a distinct weekend effect, with higher radical concentrations observed on the weekends corresponding to lower levels of nitrogen oxides (NOx). The radical measurements were compared to results from a zero-dimensional model using the Regional Atmospheric Chemical Mechanism-2 constrained by NOx and other measured trace gases. The chemical model overpredicted measured OH concentrations during the weekends by a factor of approximately 1.4 ± 0.3 (1σ), but the agreement was better during the weekdays (ratio of 1.0 ± 0.2). Model predicted HO2* concentrations underpredicted by a factor of 1.3 ± 0.2 on the weekends, while measured weekday concentrations were underpredicted by a factor of 3.0 ± 0.5. However, increasing the modeled OH reactivity to match the measured total OH reactivity improved the overall agreement for both OH and HO2* on all days. A radical budget analysis suggests that photolysis of carbonyls and formaldehyde together accounted for approximately 40% of radical initiation with photolysis of nitrous acid accounting for 30% at the measurement height and ozone photolysis contributing less than 20%. An analysis of the ozone production sensitivity reveals that during the week, ozone production was limited by volatile organic compounds throughout the day during the campaign but NOx limited during the afternoon on the weekends.

  7. [Radicalism and feminism: The case of Poulain de la Barre].

    Science.gov (United States)

    Pellegrin, Marie-Frédérique

    2015-12-01

    Early modern radicalism and its criteria are described and defined by Jonathan Israel in various works. Poulain de la Barre, one of the first modern feminist thinkers, first is used by Israel as an example of the so-called radical Enlightenment and finally is rejected as such. This case study exhibed the necessity of questionning the coherence of the required criteria for defining a « radical » thinker, especially when examinating carefully the last paragraph of Spinoza's Political Treatise.

  8. Copper-catalyzed radical carbooxygenation: alkylation and alkoxylation of styrenes.

    Science.gov (United States)

    Liao, Zhixiong; Yi, Hong; Li, Zheng; Fan, Chao; Zhang, Xu; Liu, Jie; Deng, Zixin; Lei, Aiwen

    2015-01-01

    A simple copper-catalyzed direct radical carbooxygenation of styrenes is developed utilizing alkyl bromides as radical resources. This catalytic radical difunctionalization accomplishes both alkylation and alkoxylation of styrenes in one pot. A broad range of styrenes and alcohols are well tolerated in this transformation. The EPR experiment shows that alkyl halides could oxidize Cu(I) to Cu(II) in this transformation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Living Together v. Living Well Together: A Normative Examination of the SAS Case

    Directory of Open Access Journals (Sweden)

    Lori G. Beaman

    2016-04-01

    Full Text Available The European Court of Human Rights decision in SAS from France illustrates how a policy and national mantra that ostensibly aims to enhance inclusiveness, ‘living together’, is legally deployed in a manner that may have the opposite effect. In essence, despite acknowledging the sincerity of SAS’s religious practice of wearing the niqab, and her agency in making the decision to do so, the Court focuses on radicalism and women’s oppression amongst Muslims. Taking the notion of living together as the beginning point, the paper explores the normative assumptions underlying this notion as illustrated in the judgment of the Court. An alternative approach, drawing on the work of Derrida for the notion of ‘living well together’ will be proposed and its implications for social inclusion explicated. The paper’s aim is to move beyond the specific example of SAS and France to argue that the SAS pattern of identifying particular values as ‘national values’, the deployment of those values through law, policy and public discourse, and their exclusionary effects is playing out in a number of Western democracies, including Canada, the country with which the author is most familiar. Because of this widespread dissemination of values and their framing as representative of who ‘we’ are, there is a pressing need to consider the potentially alienating effects of a specific manifestation of ‘living together’ and an alternative model of ‘living well together’.

  10. Controlled radical polymerization of acrylates by {gamma}-irradiation in the presence of 1,1-diphenylethene

    Energy Technology Data Exchange (ETDEWEB)

    Wu Zongtao [Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang Zhicheng [Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)]. E-mail: zczhang@ustc.edu.cn

    2005-12-15

    Poly (butyl acrylate) and poly (methyl acrylate) were successfully prepared in the presence of 1,1-diphenylethene (DPE) by {gamma}-irradiation-induced polymerization in both bulk and solution. The influences of polymerization time, amounts of DPE in system on conversion, molecular weight (MW) and its distribution (M{sub w}/M{sub n}) were studied. The results indicate that the polymerization initiated by {gamma}-irradiation in the presence of DPE shows the character of living radical reaction.

  11. Radical polarization in double switching of external magnetic field

    International Nuclear Information System (INIS)

    Lukzen, N.N.; Morozov, V.A.; Sagdeev, R.Z.

    1999-01-01

    Theoretical treatment of radical spin evolution under the action of double switching of external magnetic field is proposed. Account is taken of evolution of the radical spin state during laser pulse which generates paramagnetic particles. It is shown that the most effective beats in the nuclear magnetization of diamagnetic products of recombination occur upon the jump into zero magnetic field after laser pulse. The phase of observed beats bears information about the type of the initial radical polarization. The frequency of the beats is determined by radical hyperfine structure. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  12. The research progress of several kinds of free radical scavengers

    International Nuclear Information System (INIS)

    Qian Liren; Huang Yuecheng; Cai Jianming

    2009-01-01

    Ionization radiation can generate free radicals in biological system, which could induce lipid peroxi-dation, biomacromolecule and biomembrane damage, lost of cell function, cell cycle disturbance, genetic mutation and so on. The scavenging free radicals can protect organism from radiation damage. Many radio-protective agents, such as amylase, hydroxyl-benzene derivatives, hormone, vitamin, have great abilities to protect organism from radiation via scavenging free radicals. In this paper, we mainly review the free radical scavenging effects of several kinds of radio-protective agents. (authors)

  13. Progress on resonance ionization detection of combustion radicals

    International Nuclear Information System (INIS)

    Cool, T.A.

    1994-01-01

    Selective laser ionization techniques are used in our laboratory for the measurement of concentration profiles of radical intermediates in the combustion of chlorinated hydrocarbon flames. A new ultrasensitive detection technique, made possible with the advent of tunable VUV laser sources, enables the selective near-threshold photoionization of all radical intermediates in premixed hydrocarbon and chlorinated hydrocarbon flames. The progress made on the following three separate experiments during the past year is briefly described in this report. Flame Radical Concentration Measurements with VUV Spectroscopy; observation of hyperfine quantum beats in cyanogen; and the spectroscopy of the ClCO radical

  14. Incontinence and Erectile Dysfunction Following Radical Prostatectomy: A Review

    Directory of Open Access Journals (Sweden)

    Gerasimos Alivizatos

    2005-01-01

    Full Text Available Radical prostatectomy remains the treatment of choice for localized prostate cancer in age-appropriate and health-appropriate men. Although cancer control is the most important aspect of a radical prostatectomy, minimization of postoperative morbidity, especially urinary incontinence and erectile dysfunction, is becoming a greater concern. We reviewed recent data available on Medline regarding the incidence, pathophysiology, evaluation, and treatment of incontinence and sexual dysfunction after radical prostatectomy. Health-related quality of life issues have been specifically addressed. Although low incidences of incontinence and erectile dysfunction after radical prostatectomy have been reported in the hands of experienced surgeons, the literature review revealed a great variety, with incontinence rates ranging from 0.3–65.6% and potency rates ranging from 11–87%. Several factors contribute to this wide difference, the most important being the application of a meticulous surgical technique. General and cancer-specific health-related quality of life is not being affected after radical prostatectomy. The incidence of incontinence and erectile dysfunction is higher after radical prostatectomy when compared to the incidence observed when other therapies for localized prostate cancer are applied. However, the majority of the patients undergoing radical prostatectomy would vote for the operation again. Today, avoidance of major complications after radical prostatectomy depends mostly on a high-quality surgical technique. When incontinence or erectile dysfunction persists after radical prostatectomy, the majority of the treated patients can be managed effectively by various methods.

  15. Live your questions now

    OpenAIRE

    Brownrigg, Jenny

    2016-01-01

    'Live Your Questions Now' is a case study for Cubitt Education's publication 'Aging in Public: creative practice in ageing and the public realm from across the UK', edited by Daniel Baker and published by Cubitt Gallery, Studios and Education, London in 2016. The publication was linked to Cubitt's programme 'Public Wisdom' (2011-2015). My case study is about 'Live your questions now', a group exhibition I curated in 2011 for Mackintosh Museum, The Glasgow School of Art. 'Live your questions n...

  16. Administration for Community Living

    Science.gov (United States)

    ... 15, 2017 Grants from the National Institute on Disability, Independent Living, and Rehabilitation Research ... integration, and inclusion throughout life Other ACL Sites Eldercare Locator OlderIndians. ...

  17. THE ARABIC ORIGINS OF ENGLISH AND INDO-EUROPEAN "URBAN TERMS": A RADICAL LINGUISTIC THEORY APPROACH

    Directory of Open Access Journals (Sweden)

    Zaidan Ali Jassem

    2015-06-01

    Full Text Available This paper traces the Arabic origins of English, German, French, Latin, Greek, and Sanskrit "urban terms" from a radical linguistic (or lexical root theory perspective. The data comprises 130 such terms like abide, building, city, construction, courtyard, hotel, house, live, mansion, mason, palace, metropolis, residence, road, rural, sedentary, sojourn, stay, structure, tent, town, urban, villa, village, zoo, and so on. The results clearly show that all such words have true Arabic cognates with the same or similar forms and meanings, whose differences are due to natural and plausible causes and different routes of linguistic change. Moreover, the results support the adequacy of the radical linguistic theory according to which, unlike the Comparative Method and/or Family Tree Model, Arabic, English, German, French, Latin, Greek, and Sanskrit are dialects of the same language or family, renamed Eurabian or Urban family, with Arabic being their origin all for sharing the whole cognates with them and for its huge phonetic, morphological, grammatical, and lexical variety and wealth. Also, they indicate that there is a radical language from which all human languages stemmed and which has been preserved almost intact in Arabic as the most conservative and productive language, without which it is impossible to interpret its linguistic richness and versatility on all levels.

  18. A DFT study on the deprotonation antioxidant mechanistic step of ortho-substituted phenolic cation radicals

    International Nuclear Information System (INIS)

    Vafiadis, Anastasios P.; Bakalbassis, Evangelos G.

    2005-01-01

    The conformers of the 2-, 3- and 4-substituted phenolic cation radicals, 2-X-, 3-X- and 4-X-ArOH ·+ , and the respective phenoxyl radicals, ArO · , the intramolecular hydrogen bond strength (ΔH intra ) estimate along with the electronic effects of five electron withdrawing (EWG) and eight electron donating groups (EDG) on the gas-phase O-H proton dissociation enthalpies, (PDEs), of the short-lived, 2-X-ArOH ·+ , (involved in the single-electron transfer antioxidant mechanism), are studied at the DFT/B3LYP level of theory. EWG result to smaller PDEs, hence to stronger acidity; EDG to weaker acidity. The deprotonation antioxidant mechanistic step is not a rate-controlling step for 2-X-ArOH to scavenge free radicals. Approximate estimations of the ΔPDEs (hence acidities as well) can be derived from calculated structural and/or vibrational frequency values. ΔH intra s correlate reasonably with geometrical parameters for the closed-shell, neutral counterparts, in contrast with previous estimates

  19. Influence of the irradiation temperature on the free-radical response of alanine

    International Nuclear Information System (INIS)

    Wieser, A.; Siegele, R.; Regulla, D.F.

    1989-01-01

    GSF operates the only IAEA high-level dosimetry reference laboratory and, as a joint project with the IAEA, the International Dose Assurance Service (IDAS). Dosimetry is based on long-lived free radicals in organic alanine induced by ionizing radiation and readout by ESR spectroscopy. The thermal time response of the radical concentration in alanine is fairly constant after irradiation provided that the alanine samples are stored at temperatures below 50 0 C. By contrast, a positive temperature coefficient had earlier been found at GSF for the production rate of alanine radicals, for irradiation temperatures between 0 and 50 0 C. This effect has to be considered for reference dosimetry in radiation processing. Radiation processing is also of interest at irradiation temperatures below 0 0 C. The present study describes experiments on the influence of irradiation temperatures between +50 and -100 0 C. Comparison is made between the present and earlier results, in the overlapping temperature range. An empirical function is proposed for the temperature coefficient based on the experimental data. (author)

  20. DEMOCRACIA RADICAL Y CIUDADANÍA

    Directory of Open Access Journals (Sweden)

    Pedro Pablo Serna

    2008-01-01

    Full Text Available En el presente texto se presentan dos miradas con respecto a la democracia y su relación con el pensamiento liberal, mostrando de manera específica las características principales de la democracia radical y la manera como ésta puede realizar un adecuado encuentro entre lo individual y lo social, sin afectar las garantías mínimas que se le deben dar a todos los individuos para la realización de su propia concepción de bien. Debe propiciar también unas condiciones adecuadas de participación y control sobre lo público. Para ello, mostraré las visiones de Hayek y Nozick, confrontadas con la mirada de autores como Mouffe, Fraser y otros, quienes proponen un sentido viable, más amplio e incluyente de democracia.

  1. Spectroscopy, Kinetics, and Dynamics of Combustion Radicals

    Energy Technology Data Exchange (ETDEWEB)

    Nesbitt, David J. [Research/Professor

    2013-08-06

    Spectroscopy, kinetics and dynamics of jet cooled hydrocarbon transients relevant to the DOE combustion mission have been explored, exploiting i) high resolution IR lasers, ii) slit discharge sources for formation of jet cooled radicals, and iii) high sensitivity detection with direct laser absorption methods and near the quantum shot noise limit. What makes this combination powerful is that such transients can be made under high concentrations and pressures characteristic of actual combustion conditions, and yet with the resulting species rapidly cooled (T ≈10-15K) in the slit supersonic expansion. Combined with the power of IR laser absorption methods, this provides novel access to spectral detection and study of many critical combustion species.

  2. Schoenberg and the Radical Economies of Harmonielehre

    Directory of Open Access Journals (Sweden)

    Murray Dineen

    2009-06-01

    Full Text Available This article examines Schoenberg’s Harmonielehre as a text shaped by the influence of Central European science and politics. In accord with a severely economical approach to his subject, Schoenberg’s critique of figured bass and chorale harmonization is compared with Ernst Mach’s writings on scientific method. In support of this comparison, the article addresses the role played in Schoenberg’s political development by the Leftist editor and organizer, David J. Bach, one of Schoenberg’s closest childhood friends and a student of Mach. The comparison between Schoenberg and Mach, then, is drawn not only in terms of scientific method but also in light of the radical politics of the Austrian Left at the time, a politics for which both Mach and Schoenberg held sympathies. It should not be overlooked that later, however, they ceased to acknowledge these sympathies explicitly, and Schoenberg would appear to have abandoned them entirely.

  3. CN radical in diffuse interstellar clouds

    International Nuclear Information System (INIS)

    Federman, S.R.; Danks, A.C.; Lambert, D.L.

    1984-01-01

    A survey of 15 lines of sight for the CN B 2 Σ + --X 2 Σ + interstellar absorption lines shows that the CN column density in diffuse interstellar clouds follows the relation log N(CN)proportionalm log N(H 2 ), where mroughly-equal3. This result is reproduced by a reaction network in which CN is produced primarily from C 2 by the neutral-neutral reaction C 2 +N → CN+C, and photodissociation is the main destruction pathway for the neutral molecules CH, C 2 , and CN. The CN radical is the first molecular species observed in diffuse clouds that requires a neutral-neutral reaction for its formation in the gas phase. The network also reproduces the observed ratio N(CN)/N(H 2 )

  4. ESR study of free radicals in mango

    Science.gov (United States)

    Kikuchi, Masahiro; Hussain, Mohammad S.; Morishita, Norio; Ukai, Mitsuko; Kobayashi, Yasuhiko; Shimoyama, Yuhei

    2010-01-01

    An electron spin resonance (ESR) spectroscopic study of radicals induced in irradiated fresh mangoes was performed. Mangoes in the fresh state were irradiated with γ-rays, lyophilized and then crushed into a powder. The ESR spectrum of the powder showed a strong main peak at g = 2.004 and a pair of peaks centered at the main peak. The main peak was detected from both flesh and skin specimens. This peak height gradually decreased during storage following irradiation. On the other hand, the side peaks showed a well-defined dose-response relationship even at 9 days post-irradiation. The side peaks therefore provide a useful means to define the irradiation of fresh mangoes.

  5. Intramolecular hydrogen bonding in malonaldehyde and its radical analogues.

    Science.gov (United States)

    Lin, Chen; Kumar, Manoj; Finney, Brian A; Francisco, Joseph S

    2017-09-28

    High level Brueckner doubles with triples correction method-based ab initio calculations have been used to investigate the nature of intramolecular hydrogen bonding and intramolecular hydrogen atom transfer in cis-malonaldehyde (MA) and its radical analogues. The radicals considered here are the ones that correspond to the homolytic cleavage of C-H bonds in cis-MA. The results suggest that cis-MA and its radical analogues, cis-MA RS , and cis-MA RA , both exist in planar geometry. The calculated intramolecular O-H⋯O=C bond in cis-MA is shorter than that in the radical analogues. The intramolecular hydrogen bond in cis-MA is stronger than in its radicals by at least 3.0 kcal/mol. The stability of a cis-malonaldehyde radical correlates with the extent of electron spin delocalization; cis-MA RA , in which the radical spin is more delocalized, is the most stable MA radical, whereas cis-MA RS , in which the radical spin is strongly localized, is the least stable radical. The natural bond orbital analysis indicates that the intramolecular hydrogen bonding (O⋯H⋯O) in cis-malonaldehyde radicals is stabilized by the interaction between the lone pair orbitals of donor oxygen and the σ * orbital of acceptor O-H bond (n → σ * OH ). The calculated barriers indicate that the intramolecular proton transfer in cis-MA involves 2.2 kcal/mol lower barrier than that in cis-MA RS .

  6. Radical radiotherapy for T3 laryngeal cancers

    Energy Technology Data Exchange (ETDEWEB)

    Uno, T. [International Medical Center of Japan, Tokyo (Japan). Dept. of Radiation Therapy; Itami, J. [International Medical Center of Japan, Tokyo (Japan). Dept. of Radiation Therapy; Kotaka, K. [International Medical Center of Japan, Tokyo (Japan). Dept. of Radiation Therapy; Toriyama, M. [International Medical Center of Japan, Tokyo (Japan). Dept. of Otolaryngology

    1996-08-01

    From 1974 through 1992, 37 previously untreated patients with T3 laryngeal cancer (supraglottic 15, glottic 22) were treated with initial radical radiotherapy and surgery for salvage. Two-year local control rate with radiotherapy alone, ultimate voice preservation rate, and ultimate local control rate for T3 supraglottic cancer were 33%, 33%, and 60%, respectively. Corresponding figures for T3 glottic cancer were 32%, 23%, and 77%, respecitvely. Five-year cause-specific survival rate for T3 supraglottic cancer and glottic cancer were 47% and 77%, respectively. In T3 supraglottic cancer, none of the 4 patients with subglottic tumor extension attained local control by radiotherapy alone, and local-regional recurrence-free time were significantly shorter in patients with subglottic tumor extension or tracheostomy before radiotherapy. There were no serious late complications such as chondronecrosis, rupture of carotid artery attributed to radical radiotherapy, while 3 patients had severe laryngeal edema requiring total laryngectomy. (orig.) [Deutsch] Von 1974 bis 1992 wurden 37 zuvor nicht behandelte Patienten mit T3-Larynxkarzinomen (15 supraglottisch, 22 glottisch) primaer kurativ bestrahlt und, wenn erforderlich, einer Salvage-Operation unterzogen. Die Zwei-Jahres-Kontrollrate bei alleiniger Strahlentherapie, die Rate der Stimmerhaltung sowie die unter Einschluss der Operation erreichbare lokale Kontrollrate bei supraglottischen T3-Larynxkarzinomen betrugen 33%, 33% und 60%. Bei glottischen T3-Karzinomen wurden jeweils 32%, 23% und 77% erreicht. Die Fuenf-Jahres-Ueberlebensrate betrug 47% bei supraglottischen T3-Karzinomen und 77% bei den glottischen Karzinomen. Im Fall von supraglottischen Karzinomen erreichte keiner der vier Patienten mit subglottischer Tumorausdehnung eine lokale Kontrolle durch alleinige Strahlentherapie. Die lokoregionale rezidivfreie Zeit war bei den Patienten mit subglottischer Tumorausdehnung oder Tracheostomie vor Einleitung der

  7. Live and Dead Nodes

    DEFF Research Database (Denmark)

    Jørgensen, Sune Lehman; Jackson, A. D.

    2005-01-01

    In this paper, we explore the consequences of a distinction between `live' and `dead' network nodes; `live' nodes are able to acquire new links whereas `dead' nodes are static. We develop an analytically soluble growing network model incorporating this distinction and show that it can provide...

  8. Laccase catalyzed grafting of-N-OH type mediators to lignin via radical-radical coupling

    DEFF Research Database (Denmark)

    Munk, Line; Punt, A. M.; Kabel, M. A.

    2017-01-01

    Lignin is an underexploited resource in biomass refining. Laccases (EC 1.10.3.2) catalyze oxidation of phenolic hydroxyls using O2 as electron acceptor and may facilitate lignin modification in the presence of mediators. This study assessed the reactivity of four different synthetic mediators...... better than HBT (1-hydroxybenzotriazole). Three different mechanisms are suggested to explain the grafting of HPI and HBT, all involving radical-radical coupling to produce covalent bonding to lignin. Lignin from exhaustive cellulase treatment of wheat straw was more susceptible to grafting than beech...... organosolv lignin with the relative abundance of grafting being 35% vs. 11% for HPI and 5% vs. 1% for HBT on these lignin substrates. The data imply that lignin can be functionalized via laccase catalysis with-N-OH type mediators....

  9. Evaluating Living Standard Indicators

    Directory of Open Access Journals (Sweden)

    Birčiaková Naďa

    2015-09-01

    Full Text Available This paper deals with the evaluation of selected available indicators of living standards, divided into three groups, namely economic, environmental, and social. We have selected six countries of the European Union for analysis: Bulgaria, the Czech Republic, Hungary, Luxembourg, France, and Great Britain. The aim of this paper is to evaluate indicators measuring living standards and suggest the most important factors which should be included in the final measurement. We have tried to determine what factors influence each indicator and what factors affect living standards. We have chosen regression analysis as our main method. From the study of factors, we can deduce their impact on living standards, and thus the value of indicators of living standards. Indicators with a high degree of reliability include the following factors: size and density of population, health care and spending on education. Emissions of carbon dioxide in the atmosphere also have a certain lower degree of reliability.

  10. Living with others

    DEFF Research Database (Denmark)

    Zabiliute, Emilija

    Living with Others’ is an ethnographic study of everyday lives and health-seeking practices among urban poor living in a settlement in the margins of Delhi, India.By exploring subjectivities, lived experiences of poverty, and relations through a prism ofhealth, the inquiry aims to move beyond...... the explorations of precarity embedded in political economies and urban governance that dominate discussions on urban poor neighbourhoods in India.Empirically, the study draws on long-term ethnographic fieldwork and interviews among urban poor,mostly women;and formal and informal health practitioners, abundant...... in the area. Among these are governmental interventions,run under a maternal health developmental programme, National Rural Health Mission.The study argues that the vulnerabilities characterisingthe lives of the urban poor unfold and are negotiated through relations with kin, neighbours, and political patrons...

  11. Two-photon laser-induced fluorescence studies of HS radicals, DS radicals, and I atoms

    Energy Technology Data Exchange (ETDEWEB)

    Tiee, J J; Ferris, M J; Loge, G W; Wampler, F B

    1983-04-15

    A two-photon laser-induced excitation and fluorescence technique has been used to study the A /sup 2/..sigma../sup +/ - X/sup 2/PI transition of HS and DS radicals and various high-lying /sup 4/P/sup 0/, /sup 2/D/sup 0/, and /sup 4/D/sup 0/ states of the I atom. The two-photon excitation cross sections and detection sensitivity are discussed. 13 references, 5 figures.

  12. ESR study of the anion radicals of 5-nitropyrimidines: conversion to iminoxy radicals

    International Nuclear Information System (INIS)

    Sevilla, M.D.; Clark, C.; Failor, R.

    1976-01-01

    The anion radicals of a number of 5-nitropyrimidines have been investigated by ESR spectroscopy. The anions are formed by electrolysis in dimethylformamide and by electron attachment in aqueous glasses, 12 M LiCl--D 2 O and 8 M NaOD. The electrolysis of 5-nitrouracil and 5-nitro-6-methyluracil results in relatively stable anion radicals. The results for 5-nitrouracil give evidence for two or perhaps three anions which differ only by the degree of ring nitrogen protonation. The results for 5-nitro-6-methyluracil suggest that the nitro group of the anion is twisted so that it is coupled only weakly to the ring π-electron system. The anions of 5-nitrouracil, 5-nitroorotic acid, 5-nitrobarbituric acid, and 5-nitro-6-methyluracil have been produced in the alkaline and neutral aqueous glasses. The anisotropic spectra found have been analyzed with the aid of computer simulations which assume axial symmetry. For example, the analysis of the spectrum of 5-nitrouracil anion in 12 M LiCl yields A/sub parallel//sup N/ = 33; A/sub perpendicular to//sup N/ = 5, a 6 /sup H/ = 5.5 G, g/sub parallel/ = 2.0016, and g/sub perpendicular to/ = 2.0059. A concentration dependence in the splittings is noted and discussed. Ultraviolet photolysis of the anions of 5-nitro-6-methyluracil and 5-nitrobarbituric acid results in the formation of iminoxy radicals. Mechanisms of formation of the iminoxy radicals are discussed and results found in this work are compared to results found in single crystals and aqueous solution

  13. Uma análise behaviorista radical dos sonhos A radical behaviorist analysis of the dreams

    Directory of Open Access Journals (Sweden)

    Francynete Melo e Silva

    2000-01-01

    Full Text Available Embora não haja um consenso acerca de questões sobre o que são os sonhos, porque sonhamos, etc., a maioria dos estudos sobre a natureza dos sonhos concorda que ela está relacionada a condições internas do organismo. Contrariamente, o behaviorismo radical analisa os sonhos como comportamentos privados, sendo produtos das histórias filogenética, ontogenética e cultural. Neste sentido, este trabalho tem como objetivo analisar os sonhos a partir da perspectiva behaviorista radical, considerando-os como comportamentos perceptuais encobertos, argumentando-se que são aprendidos. Afirma-se que a interpretação dos sonhos é impossível se não se conhecem as contingências de reforço com as quais a pessoa está interagindo.In spite of the fact that there is no consensus concerning questions about the nature and origin of dreams, the majority of the studies on the nature of the dreams agrees that they are related to internal conditions of the organism. As opposed to that notion, the radical behaviorism analyses the dreams as private behaviors and, thus, as products of philogenetical, ontogenetical, and cultural histories. In this sense, this paper aims to analyze the dreams from a radical behaviorism perspective, considering them as private events, perceptual behaviors, and arguing that they are learned processes. It is asserted that the dreams interpretation is impossible if the contingencies that control such activity are unknown.

  14. New insights into the aquatic photochemistry of fluoroquinolone antibiotics: Direct photodegradation, hydroxyl-radical oxidation, and antibacterial activity changes

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Linke; Na, Guangshui [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Zhang, Siyu [Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Kai [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Zhang, Peng, E-mail: pzhang@nmemc.org.cn [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Ren, Honglei; Yao, Ziwei [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China)

    2015-09-15

    The ubiquity and photoreactivity of fluoroquinolone antibiotics (FQs) in surface waters urge new insights into their aqueous photochemical behavior. This study concerns the photochemistry of 6 FQs: ciprofloxacin, danofloxacin, levofloxacin, sarafloxacin, difloxacin and enrofloxacin. Methods were developed to calculate their solar direct photodegradation half-lives (t{sub d,E}) and hydroxyl-radical oxidation half-lives (t{sub ·OH,E}) in sunlit surface waters. The t{sub d,E} values range from 0.56 min to 28.8 min at 45° N latitude, whereas t{sub ·OH,E} ranges from 3.24 h to 33.6 h, suggesting that most FQs tend to undergo fast direct photolysis rather than hydroxyl-radical oxidation in surface waters. However, a case study for levofloxacin and sarafloxacin indicated that the hydroxyl-radical oxidation induced risky photochlorination and resulted in multi-degradation pathways, such as piperazinyl hydroxylation and clearage. Changes in the antibacterial activity of FQs caused by photodegradation in various waters were further examined using Escherichia coli, and it was found that the activity evolution depended on primary photodegradation pathways and products. Primary intermediates with intact FQ nuclei retained significant antibacterial activity. These results are important for assessing the fate and risk of FQs in surface waters. - Highlights: • It is first reported on hydroxyl-radical oxidation of 6 fluoroquinolone antibiotics. • Methods were developed to assess photolysis and oxidation fate in surface waters. • The neutral form reacted faster with hydroxyl radical than protonated forms. • The main oxidation intermediates and transformation pathways were clarified. • The antibacterial activity changes depend on dominant photolysis pathways.

  15. New insights into the aquatic photochemistry of fluoroquinolone antibiotics: Direct photodegradation, hydroxyl-radical oxidation, and antibacterial activity changes

    International Nuclear Information System (INIS)

    Ge, Linke; Na, Guangshui; Zhang, Siyu; Li, Kai; Zhang, Peng; Ren, Honglei; Yao, Ziwei

    2015-01-01

    The ubiquity and photoreactivity of fluoroquinolone antibiotics (FQs) in surface waters urge new insights into their aqueous photochemical behavior. This study concerns the photochemistry of 6 FQs: ciprofloxacin, danofloxacin, levofloxacin, sarafloxacin, difloxacin and enrofloxacin. Methods were developed to calculate their solar direct photodegradation half-lives (t d,E ) and hydroxyl-radical oxidation half-lives (t ·OH,E ) in sunlit surface waters. The t d,E values range from 0.56 min to 28.8 min at 45° N latitude, whereas t ·OH,E ranges from 3.24 h to 33.6 h, suggesting that most FQs tend to undergo fast direct photolysis rather than hydroxyl-radical oxidation in surface waters. However, a case study for levofloxacin and sarafloxacin indicated that the hydroxyl-radical oxidation induced risky photochlorination and resulted in multi-degradation pathways, such as piperazinyl hydroxylation and clearage. Changes in the antibacterial activity of FQs caused by photodegradation in various waters were further examined using Escherichia coli, and it was found that the activity evolution depended on primary photodegradation pathways and products. Primary intermediates with intact FQ nuclei retained significant antibacterial activity. These results are important for assessing the fate and risk of FQs in surface waters. - Highlights: • It is first reported on hydroxyl-radical oxidation of 6 fluoroquinolone antibiotics. • Methods were developed to assess photolysis and oxidation fate in surface waters. • The neutral form reacted faster with hydroxyl radical than protonated forms. • The main oxidation intermediates and transformation pathways were clarified. • The antibacterial activity changes depend on dominant photolysis pathways

  16. Radical versus Social Constructivism: Dilemma, Dialogue, and Defense

    Science.gov (United States)

    Belbase, Shashidhar

    2011-01-01

    This paper aims to discuss epistemological and philosophical foundation of meaningful learning and teaching mathematics and science from the perspective of radical and social constructivism. I have reflected on my experiences of radical and social constructivism through dilemma, dialogue, and defense of my personal epistemology of learning. I went…

  17. Radicals versus Moderates: A Critique of Gyekye's Moderate ...

    African Journals Online (AJOL)

    The communitarian conception of person is a widely accepted view in African thought. Kwame Gyekye thinks there is a distinction between what he calls radical communitarianism and his own version of moderate communitarianism. He is of the view that radical communitarianism is faced with insurmountable problems and ...

  18. Repair Activity of trans-Resveratrol toward 2'-Deoxyguanosine Radicals.

    Science.gov (United States)

    Cheng, Xing; An, Ping; Li, Shujin; Zhou, Liping

    2018-04-26

    In the present study, the repair activity of trans-resveratrol toward 2'-deoxyguanosine (dGuo) radicals in polar and nonpolar solvents was studied using density functional theory. The hydrogen transfer/proton coupled electron transfer and single electron transfer (SET) mechanisms between trans-resveratrol and dGuo-radicals were considered. Taking into consideration the molar fraction of neutral trans-resveratrol (ROH) and anionic trans-resveratrol (RO - ), the overall rate constants for repairing dGuo-radicals by trans-resveratrol are 9.94 × 10 8 and 2.01 × 10 9 dm 3 mol -1 s -1 in polar and nonpolar solvents, respectively, and the overall rate constant of repairing cation radical (dGuo •+ ) by trans-resveratrol via an SET mechanism is 7.17 × 10 9 dm 3 mol -1 s -1 . The repair activity of RO - toward dGuo-radicals is better than that of ROH, but the repair activity of ROH toward dGuo •+ is better than that of RO - . Unfortunately, neither ROH nor RO - can repair the 2'-deoxyribose radicals of dGuo. It can therefore be concluded that trans-resveratrol is an effective antioxidant for repairing base radicals of dGuo and dGuo •+ . The study can help us understand the repair activity of trans-resveratrol toward dGuo radicals.

  19. Free radicals generated by radiolysis of aqueous solutions

    International Nuclear Information System (INIS)

    Schwarz, H.A.

    1981-01-01

    The free radicals produced in the radiolysis of aqueous solutions span the range of redox potentials from -2.9 to +2.65 volts. The identity and nature of these radicals were discussed. Most of the discussion was results obtained with low LET radiation sources ( 60 Co gamma radiation or electron accelerators). Water radiolysis provides the synthesis of many radicals and radical ions in aqueous solution. The primary radicals, e/sub aq/ - H, OH, are well characterized. The radical population can be made to be 90% pure OH (or O - ) if N 2 O solutions are irradiated, the remaining 10% being H atoms. 55% of the radicals can be converted to H atoms in acid solution or in neutral phosphate solutions(e/sub aq/ - reacts with H 2 PO 4- to produce H). The remaining 45% (OH radicals) are difficult to convert to H by reaction with H 2 , due to the slow rate of the reaction. About 100 atmospheres of H 2 are required to do the conversion in less than 10 - 6 sec. 3 figures, 3 tables. (DP)

  20. Teaching Methods in Nutrition: Free Radicals, Antioxidants, and Human Disease.

    Science.gov (United States)

    Janowiak, John J.

    This article presents a teaching methodology for free radical theory and discusses the role of antioxidants in human health. Free radicals are a normal byproduct of respiration, which allows the body to use oxygen, liberate energy, and dispose of harmful substances. The body's antioxidants and nutritional antioxidants quench most of the free…